diff options
Diffstat (limited to 'kernel/bpf/verifier.c')
| -rw-r--r-- | kernel/bpf/verifier.c | 20425 |
1 files changed, 20425 insertions, 0 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c new file mode 100644 index 000000000..a7901ed35 --- /dev/null +++ b/kernel/bpf/verifier.c @@ -0,0 +1,20425 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com + * Copyright (c) 2016 Facebook + * Copyright (c) 2018 Covalent IO, Inc. http://covalent.io + */ +#include <uapi/linux/btf.h> +#include <linux/bpf-cgroup.h> +#include <linux/kernel.h> +#include <linux/types.h> +#include <linux/slab.h> +#include <linux/bpf.h> +#include <linux/btf.h> +#include <linux/bpf_verifier.h> +#include <linux/filter.h> +#include <net/netlink.h> +#include <linux/file.h> +#include <linux/vmalloc.h> +#include <linux/stringify.h> +#include <linux/bsearch.h> +#include <linux/sort.h> +#include <linux/perf_event.h> +#include <linux/ctype.h> +#include <linux/error-injection.h> +#include <linux/bpf_lsm.h> +#include <linux/btf_ids.h> +#include <linux/poison.h> +#include <linux/module.h> +#include <linux/cpumask.h> +#include <net/xdp.h> + +#include "disasm.h" + +static const struct bpf_verifier_ops * const bpf_verifier_ops[] = { +#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \ + [_id] = & _name ## _verifier_ops, +#define BPF_MAP_TYPE(_id, _ops) +#define BPF_LINK_TYPE(_id, _name) +#include <linux/bpf_types.h> +#undef BPF_PROG_TYPE +#undef BPF_MAP_TYPE +#undef BPF_LINK_TYPE +}; + +/* bpf_check() is a static code analyzer that walks eBPF program + * instruction by instruction and updates register/stack state. + * All paths of conditional branches are analyzed until 'bpf_exit' insn. + * + * The first pass is depth-first-search to check that the program is a DAG. + * It rejects the following programs: + * - larger than BPF_MAXINSNS insns + * - if loop is present (detected via back-edge) + * - unreachable insns exist (shouldn't be a forest. program = one function) + * - out of bounds or malformed jumps + * The second pass is all possible path descent from the 1st insn. + * Since it's analyzing all paths through the program, the length of the + * analysis is limited to 64k insn, which may be hit even if total number of + * insn is less then 4K, but there are too many branches that change stack/regs. + * Number of 'branches to be analyzed' is limited to 1k + * + * On entry to each instruction, each register has a type, and the instruction + * changes the types of the registers depending on instruction semantics. + * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is + * copied to R1. + * + * All registers are 64-bit. + * R0 - return register + * R1-R5 argument passing registers + * R6-R9 callee saved registers + * R10 - frame pointer read-only + * + * At the start of BPF program the register R1 contains a pointer to bpf_context + * and has type PTR_TO_CTX. + * + * Verifier tracks arithmetic operations on pointers in case: + * BPF_MOV64_REG(BPF_REG_1, BPF_REG_10), + * BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20), + * 1st insn copies R10 (which has FRAME_PTR) type into R1 + * and 2nd arithmetic instruction is pattern matched to recognize + * that it wants to construct a pointer to some element within stack. + * So after 2nd insn, the register R1 has type PTR_TO_STACK + * (and -20 constant is saved for further stack bounds checking). + * Meaning that this reg is a pointer to stack plus known immediate constant. + * + * Most of the time the registers have SCALAR_VALUE type, which + * means the register has some value, but it's not a valid pointer. + * (like pointer plus pointer becomes SCALAR_VALUE type) + * + * When verifier sees load or store instructions the type of base register + * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, PTR_TO_STACK, PTR_TO_SOCKET. These are + * four pointer types recognized by check_mem_access() function. + * + * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value' + * and the range of [ptr, ptr + map's value_size) is accessible. + * + * registers used to pass values to function calls are checked against + * function argument constraints. + * + * ARG_PTR_TO_MAP_KEY is one of such argument constraints. + * It means that the register type passed to this function must be + * PTR_TO_STACK and it will be used inside the function as + * 'pointer to map element key' + * + * For example the argument constraints for bpf_map_lookup_elem(): + * .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL, + * .arg1_type = ARG_CONST_MAP_PTR, + * .arg2_type = ARG_PTR_TO_MAP_KEY, + * + * ret_type says that this function returns 'pointer to map elem value or null' + * function expects 1st argument to be a const pointer to 'struct bpf_map' and + * 2nd argument should be a pointer to stack, which will be used inside + * the helper function as a pointer to map element key. + * + * On the kernel side the helper function looks like: + * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) + * { + * struct bpf_map *map = (struct bpf_map *) (unsigned long) r1; + * void *key = (void *) (unsigned long) r2; + * void *value; + * + * here kernel can access 'key' and 'map' pointers safely, knowing that + * [key, key + map->key_size) bytes are valid and were initialized on + * the stack of eBPF program. + * } + * + * Corresponding eBPF program may look like: + * BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), // after this insn R2 type is FRAME_PTR + * BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK + * BPF_LD_MAP_FD(BPF_REG_1, map_fd), // after this insn R1 type is CONST_PTR_TO_MAP + * BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), + * here verifier looks at prototype of map_lookup_elem() and sees: + * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok, + * Now verifier knows that this map has key of R1->map_ptr->key_size bytes + * + * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far, + * Now verifier checks that [R2, R2 + map's key_size) are within stack limits + * and were initialized prior to this call. + * If it's ok, then verifier allows this BPF_CALL insn and looks at + * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets + * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function + * returns either pointer to map value or NULL. + * + * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off' + * insn, the register holding that pointer in the true branch changes state to + * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false + * branch. See check_cond_jmp_op(). + * + * After the call R0 is set to return type of the function and registers R1-R5 + * are set to NOT_INIT to indicate that they are no longer readable. + * + * The following reference types represent a potential reference to a kernel + * resource which, after first being allocated, must be checked and freed by + * the BPF program: + * - PTR_TO_SOCKET_OR_NULL, PTR_TO_SOCKET + * + * When the verifier sees a helper call return a reference type, it allocates a + * pointer id for the reference and stores it in the current function state. + * Similar to the way that PTR_TO_MAP_VALUE_OR_NULL is converted into + * PTR_TO_MAP_VALUE, PTR_TO_SOCKET_OR_NULL becomes PTR_TO_SOCKET when the type + * passes through a NULL-check conditional. For the branch wherein the state is + * changed to CONST_IMM, the verifier releases the reference. + * + * For each helper function that allocates a reference, such as + * bpf_sk_lookup_tcp(), there is a corresponding release function, such as + * bpf_sk_release(). When a reference type passes into the release function, + * the verifier also releases the reference. If any unchecked or unreleased + * reference remains at the end of the program, the verifier rejects it. + */ + +/* verifier_state + insn_idx are pushed to stack when branch is encountered */ +struct bpf_verifier_stack_elem { + /* verifer state is 'st' + * before processing instruction 'insn_idx' + * and after processing instruction 'prev_insn_idx' + */ + struct bpf_verifier_state st; + int insn_idx; + int prev_insn_idx; + struct bpf_verifier_stack_elem *next; + /* length of verifier log at the time this state was pushed on stack */ + u32 log_pos; +}; + +#define BPF_COMPLEXITY_LIMIT_JMP_SEQ 8192 +#define BPF_COMPLEXITY_LIMIT_STATES 64 + +#define BPF_MAP_KEY_POISON (1ULL << 63) +#define BPF_MAP_KEY_SEEN (1ULL << 62) + +#define BPF_MAP_PTR_UNPRIV 1UL +#define BPF_MAP_PTR_POISON ((void *)((0xeB9FUL << 1) + \ + POISON_POINTER_DELTA)) +#define BPF_MAP_PTR(X) ((struct bpf_map *)((X) & ~BPF_MAP_PTR_UNPRIV)) + +static int acquire_reference_state(struct bpf_verifier_env *env, int insn_idx); +static int release_reference(struct bpf_verifier_env *env, int ref_obj_id); +static void invalidate_non_owning_refs(struct bpf_verifier_env *env); +static bool in_rbtree_lock_required_cb(struct bpf_verifier_env *env); +static int ref_set_non_owning(struct bpf_verifier_env *env, + struct bpf_reg_state *reg); +static void specialize_kfunc(struct bpf_verifier_env *env, + u32 func_id, u16 offset, unsigned long *addr); +static bool is_trusted_reg(const struct bpf_reg_state *reg); + +static bool bpf_map_ptr_poisoned(const struct bpf_insn_aux_data *aux) +{ + return BPF_MAP_PTR(aux->map_ptr_state) == BPF_MAP_PTR_POISON; +} + +static bool bpf_map_ptr_unpriv(const struct bpf_insn_aux_data *aux) +{ + return aux->map_ptr_state & BPF_MAP_PTR_UNPRIV; +} + +static void bpf_map_ptr_store(struct bpf_insn_aux_data *aux, + const struct bpf_map *map, bool unpriv) +{ + BUILD_BUG_ON((unsigned long)BPF_MAP_PTR_POISON & BPF_MAP_PTR_UNPRIV); + unpriv |= bpf_map_ptr_unpriv(aux); + aux->map_ptr_state = (unsigned long)map | + (unpriv ? BPF_MAP_PTR_UNPRIV : 0UL); +} + +static bool bpf_map_key_poisoned(const struct bpf_insn_aux_data *aux) +{ + return aux->map_key_state & BPF_MAP_KEY_POISON; +} + +static bool bpf_map_key_unseen(const struct bpf_insn_aux_data *aux) +{ + return !(aux->map_key_state & BPF_MAP_KEY_SEEN); +} + +static u64 bpf_map_key_immediate(const struct bpf_insn_aux_data *aux) +{ + return aux->map_key_state & ~(BPF_MAP_KEY_SEEN | BPF_MAP_KEY_POISON); +} + +static void bpf_map_key_store(struct bpf_insn_aux_data *aux, u64 state) +{ + bool poisoned = bpf_map_key_poisoned(aux); + + aux->map_key_state = state | BPF_MAP_KEY_SEEN | + (poisoned ? BPF_MAP_KEY_POISON : 0ULL); +} + +static bool bpf_helper_call(const struct bpf_insn *insn) +{ + return insn->code == (BPF_JMP | BPF_CALL) && + insn->src_reg == 0; +} + +static bool bpf_pseudo_call(const struct bpf_insn *insn) +{ + return insn->code == (BPF_JMP | BPF_CALL) && + insn->src_reg == BPF_PSEUDO_CALL; +} + +static bool bpf_pseudo_kfunc_call(const struct bpf_insn *insn) +{ + return insn->code == (BPF_JMP | BPF_CALL) && + insn->src_reg == BPF_PSEUDO_KFUNC_CALL; +} + +struct bpf_call_arg_meta { + struct bpf_map *map_ptr; + bool raw_mode; + bool pkt_access; + u8 release_regno; + int regno; + int access_size; + int mem_size; + u64 msize_max_value; + int ref_obj_id; + int dynptr_id; + int map_uid; + int func_id; + struct btf *btf; + u32 btf_id; + struct btf *ret_btf; + u32 ret_btf_id; + u32 subprogno; + struct btf_field *kptr_field; +}; + +struct bpf_kfunc_call_arg_meta { + /* In parameters */ + struct btf *btf; + u32 func_id; + u32 kfunc_flags; + const struct btf_type *func_proto; + const char *func_name; + /* Out parameters */ + u32 ref_obj_id; + u8 release_regno; + bool r0_rdonly; + u32 ret_btf_id; + u64 r0_size; + u32 subprogno; + struct { + u64 value; + bool found; + } arg_constant; + + /* arg_{btf,btf_id,owning_ref} are used by kfunc-specific handling, + * generally to pass info about user-defined local kptr types to later + * verification logic + * bpf_obj_drop + * Record the local kptr type to be drop'd + * bpf_refcount_acquire (via KF_ARG_PTR_TO_REFCOUNTED_KPTR arg type) + * Record the local kptr type to be refcount_incr'd and use + * arg_owning_ref to determine whether refcount_acquire should be + * fallible + */ + struct btf *arg_btf; + u32 arg_btf_id; + bool arg_owning_ref; + + struct { + struct btf_field *field; + } arg_list_head; + struct { + struct btf_field *field; + } arg_rbtree_root; + struct { + enum bpf_dynptr_type type; + u32 id; + u32 ref_obj_id; + } initialized_dynptr; + struct { + u8 spi; + u8 frameno; + } iter; + u64 mem_size; +}; + +struct btf *btf_vmlinux; + +static DEFINE_MUTEX(bpf_verifier_lock); + +static const struct bpf_line_info * +find_linfo(const struct bpf_verifier_env *env, u32 insn_off) +{ + const struct bpf_line_info *linfo; + const struct bpf_prog *prog; + u32 i, nr_linfo; + + prog = env->prog; + nr_linfo = prog->aux->nr_linfo; + + if (!nr_linfo || insn_off >= prog->len) + return NULL; + + linfo = prog->aux->linfo; + for (i = 1; i < nr_linfo; i++) + if (insn_off < linfo[i].insn_off) + break; + + return &linfo[i - 1]; +} + +__printf(2, 3) static void verbose(void *private_data, const char *fmt, ...) +{ + struct bpf_verifier_env *env = private_data; + va_list args; + + if (!bpf_verifier_log_needed(&env->log)) + return; + + va_start(args, fmt); + bpf_verifier_vlog(&env->log, fmt, args); + va_end(args); +} + +static const char *ltrim(const char *s) +{ + while (isspace(*s)) + s++; + + return s; +} + +__printf(3, 4) static void verbose_linfo(struct bpf_verifier_env *env, + u32 insn_off, + const char *prefix_fmt, ...) +{ + const struct bpf_line_info *linfo; + + if (!bpf_verifier_log_needed(&env->log)) + return; + + linfo = find_linfo(env, insn_off); + if (!linfo || linfo == env->prev_linfo) + return; + + if (prefix_fmt) { + va_list args; + + va_start(args, prefix_fmt); + bpf_verifier_vlog(&env->log, prefix_fmt, args); + va_end(args); + } + + verbose(env, "%s\n", + ltrim(btf_name_by_offset(env->prog->aux->btf, + linfo->line_off))); + + env->prev_linfo = linfo; +} + +static void verbose_invalid_scalar(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, + struct tnum *range, const char *ctx, + const char *reg_name) +{ + char tn_buf[48]; + + verbose(env, "At %s the register %s ", ctx, reg_name); + if (!tnum_is_unknown(reg->var_off)) { + tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); + verbose(env, "has value %s", tn_buf); + } else { + verbose(env, "has unknown scalar value"); + } + tnum_strn(tn_buf, sizeof(tn_buf), *range); + verbose(env, " should have been in %s\n", tn_buf); +} + +static bool type_is_pkt_pointer(enum bpf_reg_type type) +{ + type = base_type(type); + return type == PTR_TO_PACKET || + type == PTR_TO_PACKET_META; +} + +static bool type_is_sk_pointer(enum bpf_reg_type type) +{ + return type == PTR_TO_SOCKET || + type == PTR_TO_SOCK_COMMON || + type == PTR_TO_TCP_SOCK || + type == PTR_TO_XDP_SOCK; +} + +static bool type_may_be_null(u32 type) +{ + return type & PTR_MAYBE_NULL; +} + +static bool reg_not_null(const struct bpf_reg_state *reg) +{ + enum bpf_reg_type type; + + type = reg->type; + if (type_may_be_null(type)) + return false; + + type = base_type(type); + return type == PTR_TO_SOCKET || + type == PTR_TO_TCP_SOCK || + type == PTR_TO_MAP_VALUE || + type == PTR_TO_MAP_KEY || + type == PTR_TO_SOCK_COMMON || + (type == PTR_TO_BTF_ID && is_trusted_reg(reg)) || + type == PTR_TO_MEM; +} + +static bool type_is_ptr_alloc_obj(u32 type) +{ + return base_type(type) == PTR_TO_BTF_ID && type_flag(type) & MEM_ALLOC; +} + +static bool type_is_non_owning_ref(u32 type) +{ + return type_is_ptr_alloc_obj(type) && type_flag(type) & NON_OWN_REF; +} + +static struct btf_record *reg_btf_record(const struct bpf_reg_state *reg) +{ + struct btf_record *rec = NULL; + struct btf_struct_meta *meta; + + if (reg->type == PTR_TO_MAP_VALUE) { + rec = reg->map_ptr->record; + } else if (type_is_ptr_alloc_obj(reg->type)) { + meta = btf_find_struct_meta(reg->btf, reg->btf_id); + if (meta) + rec = meta->record; + } + return rec; +} + +static bool subprog_is_global(const struct bpf_verifier_env *env, int subprog) +{ + struct bpf_func_info_aux *aux = env->prog->aux->func_info_aux; + + return aux && aux[subprog].linkage == BTF_FUNC_GLOBAL; +} + +static bool reg_may_point_to_spin_lock(const struct bpf_reg_state *reg) +{ + return btf_record_has_field(reg_btf_record(reg), BPF_SPIN_LOCK); +} + +static bool type_is_rdonly_mem(u32 type) +{ + return type & MEM_RDONLY; +} + +static bool is_acquire_function(enum bpf_func_id func_id, + const struct bpf_map *map) +{ + enum bpf_map_type map_type = map ? map->map_type : BPF_MAP_TYPE_UNSPEC; + + if (func_id == BPF_FUNC_sk_lookup_tcp || + func_id == BPF_FUNC_sk_lookup_udp || + func_id == BPF_FUNC_skc_lookup_tcp || + func_id == BPF_FUNC_ringbuf_reserve || + func_id == BPF_FUNC_kptr_xchg) + return true; + + if (func_id == BPF_FUNC_map_lookup_elem && + (map_type == BPF_MAP_TYPE_SOCKMAP || + map_type == BPF_MAP_TYPE_SOCKHASH)) + return true; + + return false; +} + +static bool is_ptr_cast_function(enum bpf_func_id func_id) +{ + return func_id == BPF_FUNC_tcp_sock || + func_id == BPF_FUNC_sk_fullsock || + func_id == BPF_FUNC_skc_to_tcp_sock || + func_id == BPF_FUNC_skc_to_tcp6_sock || + func_id == BPF_FUNC_skc_to_udp6_sock || + func_id == BPF_FUNC_skc_to_mptcp_sock || + func_id == BPF_FUNC_skc_to_tcp_timewait_sock || + func_id == BPF_FUNC_skc_to_tcp_request_sock; +} + +static bool is_dynptr_ref_function(enum bpf_func_id func_id) +{ + return func_id == BPF_FUNC_dynptr_data; +} + +static bool is_sync_callback_calling_kfunc(u32 btf_id); + +static bool is_sync_callback_calling_function(enum bpf_func_id func_id) +{ + return func_id == BPF_FUNC_for_each_map_elem || + func_id == BPF_FUNC_find_vma || + func_id == BPF_FUNC_loop || + func_id == BPF_FUNC_user_ringbuf_drain; +} + +static bool is_async_callback_calling_function(enum bpf_func_id func_id) +{ + return func_id == BPF_FUNC_timer_set_callback; +} + +static bool is_callback_calling_function(enum bpf_func_id func_id) +{ + return is_sync_callback_calling_function(func_id) || + is_async_callback_calling_function(func_id); +} + +static bool is_sync_callback_calling_insn(struct bpf_insn *insn) +{ + return (bpf_helper_call(insn) && is_sync_callback_calling_function(insn->imm)) || + (bpf_pseudo_kfunc_call(insn) && is_sync_callback_calling_kfunc(insn->imm)); +} + +static bool is_storage_get_function(enum bpf_func_id func_id) +{ + return func_id == BPF_FUNC_sk_storage_get || + func_id == BPF_FUNC_inode_storage_get || + func_id == BPF_FUNC_task_storage_get || + func_id == BPF_FUNC_cgrp_storage_get; +} + +static bool helper_multiple_ref_obj_use(enum bpf_func_id func_id, + const struct bpf_map *map) +{ + int ref_obj_uses = 0; + + if (is_ptr_cast_function(func_id)) + ref_obj_uses++; + if (is_acquire_function(func_id, map)) + ref_obj_uses++; + if (is_dynptr_ref_function(func_id)) + ref_obj_uses++; + + return ref_obj_uses > 1; +} + +static bool is_cmpxchg_insn(const struct bpf_insn *insn) +{ + return BPF_CLASS(insn->code) == BPF_STX && + BPF_MODE(insn->code) == BPF_ATOMIC && + insn->imm == BPF_CMPXCHG; +} + +/* string representation of 'enum bpf_reg_type' + * + * Note that reg_type_str() can not appear more than once in a single verbose() + * statement. + */ +static const char *reg_type_str(struct bpf_verifier_env *env, + enum bpf_reg_type type) +{ + char postfix[16] = {0}, prefix[64] = {0}; + static const char * const str[] = { + [NOT_INIT] = "?", + [SCALAR_VALUE] = "scalar", + [PTR_TO_CTX] = "ctx", + [CONST_PTR_TO_MAP] = "map_ptr", + [PTR_TO_MAP_VALUE] = "map_value", + [PTR_TO_STACK] = "fp", + [PTR_TO_PACKET] = "pkt", + [PTR_TO_PACKET_META] = "pkt_meta", + [PTR_TO_PACKET_END] = "pkt_end", + [PTR_TO_FLOW_KEYS] = "flow_keys", + [PTR_TO_SOCKET] = "sock", + [PTR_TO_SOCK_COMMON] = "sock_common", + [PTR_TO_TCP_SOCK] = "tcp_sock", + [PTR_TO_TP_BUFFER] = "tp_buffer", + [PTR_TO_XDP_SOCK] = "xdp_sock", + [PTR_TO_BTF_ID] = "ptr_", + [PTR_TO_MEM] = "mem", + [PTR_TO_BUF] = "buf", + [PTR_TO_FUNC] = "func", + [PTR_TO_MAP_KEY] = "map_key", + [CONST_PTR_TO_DYNPTR] = "dynptr_ptr", + }; + + if (type & PTR_MAYBE_NULL) { + if (base_type(type) == PTR_TO_BTF_ID) + strncpy(postfix, "or_null_", 16); + else + strncpy(postfix, "_or_null", 16); + } + + snprintf(prefix, sizeof(prefix), "%s%s%s%s%s%s%s", + type & MEM_RDONLY ? "rdonly_" : "", + type & MEM_RINGBUF ? "ringbuf_" : "", + type & MEM_USER ? "user_" : "", + type & MEM_PERCPU ? "percpu_" : "", + type & MEM_RCU ? "rcu_" : "", + type & PTR_UNTRUSTED ? "untrusted_" : "", + type & PTR_TRUSTED ? "trusted_" : "" + ); + + snprintf(env->tmp_str_buf, TMP_STR_BUF_LEN, "%s%s%s", + prefix, str[base_type(type)], postfix); + return env->tmp_str_buf; +} + +static char slot_type_char[] = { + [STACK_INVALID] = '?', + [STACK_SPILL] = 'r', + [STACK_MISC] = 'm', + [STACK_ZERO] = '0', + [STACK_DYNPTR] = 'd', + [STACK_ITER] = 'i', +}; + +static void print_liveness(struct bpf_verifier_env *env, + enum bpf_reg_liveness live) +{ + if (live & (REG_LIVE_READ | REG_LIVE_WRITTEN | REG_LIVE_DONE)) + verbose(env, "_"); + if (live & REG_LIVE_READ) + verbose(env, "r"); + if (live & REG_LIVE_WRITTEN) + verbose(env, "w"); + if (live & REG_LIVE_DONE) + verbose(env, "D"); +} + +static int __get_spi(s32 off) +{ + return (-off - 1) / BPF_REG_SIZE; +} + +static struct bpf_func_state *func(struct bpf_verifier_env *env, + const struct bpf_reg_state *reg) +{ + struct bpf_verifier_state *cur = env->cur_state; + + return cur->frame[reg->frameno]; +} + +static bool is_spi_bounds_valid(struct bpf_func_state *state, int spi, int nr_slots) +{ + int allocated_slots = state->allocated_stack / BPF_REG_SIZE; + + /* We need to check that slots between [spi - nr_slots + 1, spi] are + * within [0, allocated_stack). + * + * Please note that the spi grows downwards. For example, a dynptr + * takes the size of two stack slots; the first slot will be at + * spi and the second slot will be at spi - 1. + */ + return spi - nr_slots + 1 >= 0 && spi < allocated_slots; +} + +static int stack_slot_obj_get_spi(struct bpf_verifier_env *env, struct bpf_reg_state *reg, + const char *obj_kind, int nr_slots) +{ + int off, spi; + + if (!tnum_is_const(reg->var_off)) { + verbose(env, "%s has to be at a constant offset\n", obj_kind); + return -EINVAL; + } + + off = reg->off + reg->var_off.value; + if (off % BPF_REG_SIZE) { + verbose(env, "cannot pass in %s at an offset=%d\n", obj_kind, off); + return -EINVAL; + } + + spi = __get_spi(off); + if (spi + 1 < nr_slots) { + verbose(env, "cannot pass in %s at an offset=%d\n", obj_kind, off); + return -EINVAL; + } + + if (!is_spi_bounds_valid(func(env, reg), spi, nr_slots)) + return -ERANGE; + return spi; +} + +static int dynptr_get_spi(struct bpf_verifier_env *env, struct bpf_reg_state *reg) +{ + return stack_slot_obj_get_spi(env, reg, "dynptr", BPF_DYNPTR_NR_SLOTS); +} + +static int iter_get_spi(struct bpf_verifier_env *env, struct bpf_reg_state *reg, int nr_slots) +{ + return stack_slot_obj_get_spi(env, reg, "iter", nr_slots); +} + +static const char *btf_type_name(const struct btf *btf, u32 id) +{ + return btf_name_by_offset(btf, btf_type_by_id(btf, id)->name_off); +} + +static const char *dynptr_type_str(enum bpf_dynptr_type type) +{ + switch (type) { + case BPF_DYNPTR_TYPE_LOCAL: + return "local"; + case BPF_DYNPTR_TYPE_RINGBUF: + return "ringbuf"; + case BPF_DYNPTR_TYPE_SKB: + return "skb"; + case BPF_DYNPTR_TYPE_XDP: + return "xdp"; + case BPF_DYNPTR_TYPE_INVALID: + return "<invalid>"; + default: + WARN_ONCE(1, "unknown dynptr type %d\n", type); + return "<unknown>"; + } +} + +static const char *iter_type_str(const struct btf *btf, u32 btf_id) +{ + if (!btf || btf_id == 0) + return "<invalid>"; + + /* we already validated that type is valid and has conforming name */ + return btf_type_name(btf, btf_id) + sizeof(ITER_PREFIX) - 1; +} + +static const char *iter_state_str(enum bpf_iter_state state) +{ + switch (state) { + case BPF_ITER_STATE_ACTIVE: + return "active"; + case BPF_ITER_STATE_DRAINED: + return "drained"; + case BPF_ITER_STATE_INVALID: + return "<invalid>"; + default: + WARN_ONCE(1, "unknown iter state %d\n", state); + return "<unknown>"; + } +} + +static void mark_reg_scratched(struct bpf_verifier_env *env, u32 regno) +{ + env->scratched_regs |= 1U << regno; +} + +static void mark_stack_slot_scratched(struct bpf_verifier_env *env, u32 spi) +{ + env->scratched_stack_slots |= 1ULL << spi; +} + +static bool reg_scratched(const struct bpf_verifier_env *env, u32 regno) +{ + return (env->scratched_regs >> regno) & 1; +} + +static bool stack_slot_scratched(const struct bpf_verifier_env *env, u64 regno) +{ + return (env->scratched_stack_slots >> regno) & 1; +} + +static bool verifier_state_scratched(const struct bpf_verifier_env *env) +{ + return env->scratched_regs || env->scratched_stack_slots; +} + +static void mark_verifier_state_clean(struct bpf_verifier_env *env) +{ + env->scratched_regs = 0U; + env->scratched_stack_slots = 0ULL; +} + +/* Used for printing the entire verifier state. */ +static void mark_verifier_state_scratched(struct bpf_verifier_env *env) +{ + env->scratched_regs = ~0U; + env->scratched_stack_slots = ~0ULL; +} + +static enum bpf_dynptr_type arg_to_dynptr_type(enum bpf_arg_type arg_type) +{ + switch (arg_type & DYNPTR_TYPE_FLAG_MASK) { + case DYNPTR_TYPE_LOCAL: + return BPF_DYNPTR_TYPE_LOCAL; + case DYNPTR_TYPE_RINGBUF: + return BPF_DYNPTR_TYPE_RINGBUF; + case DYNPTR_TYPE_SKB: + return BPF_DYNPTR_TYPE_SKB; + case DYNPTR_TYPE_XDP: + return BPF_DYNPTR_TYPE_XDP; + default: + return BPF_DYNPTR_TYPE_INVALID; + } +} + +static enum bpf_type_flag get_dynptr_type_flag(enum bpf_dynptr_type type) +{ + switch (type) { + case BPF_DYNPTR_TYPE_LOCAL: + return DYNPTR_TYPE_LOCAL; + case BPF_DYNPTR_TYPE_RINGBUF: + return DYNPTR_TYPE_RINGBUF; + case BPF_DYNPTR_TYPE_SKB: + return DYNPTR_TYPE_SKB; + case BPF_DYNPTR_TYPE_XDP: + return DYNPTR_TYPE_XDP; + default: + return 0; + } +} + +static bool dynptr_type_refcounted(enum bpf_dynptr_type type) +{ + return type == BPF_DYNPTR_TYPE_RINGBUF; +} + +static void __mark_dynptr_reg(struct bpf_reg_state *reg, + enum bpf_dynptr_type type, + bool first_slot, int dynptr_id); + +static void __mark_reg_not_init(const struct bpf_verifier_env *env, + struct bpf_reg_state *reg); + +static void mark_dynptr_stack_regs(struct bpf_verifier_env *env, + struct bpf_reg_state *sreg1, + struct bpf_reg_state *sreg2, + enum bpf_dynptr_type type) +{ + int id = ++env->id_gen; + + __mark_dynptr_reg(sreg1, type, true, id); + __mark_dynptr_reg(sreg2, type, false, id); +} + +static void mark_dynptr_cb_reg(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, + enum bpf_dynptr_type type) +{ + __mark_dynptr_reg(reg, type, true, ++env->id_gen); +} + +static int destroy_if_dynptr_stack_slot(struct bpf_verifier_env *env, + struct bpf_func_state *state, int spi); + +static int mark_stack_slots_dynptr(struct bpf_verifier_env *env, struct bpf_reg_state *reg, + enum bpf_arg_type arg_type, int insn_idx, int clone_ref_obj_id) +{ + struct bpf_func_state *state = func(env, reg); + enum bpf_dynptr_type type; + int spi, i, err; + + spi = dynptr_get_spi(env, reg); + if (spi < 0) + return spi; + + /* We cannot assume both spi and spi - 1 belong to the same dynptr, + * hence we need to call destroy_if_dynptr_stack_slot twice for both, + * to ensure that for the following example: + * [d1][d1][d2][d2] + * spi 3 2 1 0 + * So marking spi = 2 should lead to destruction of both d1 and d2. In + * case they do belong to same dynptr, second call won't see slot_type + * as STACK_DYNPTR and will simply skip destruction. + */ + err = destroy_if_dynptr_stack_slot(env, state, spi); + if (err) + return err; + err = destroy_if_dynptr_stack_slot(env, state, spi - 1); + if (err) + return err; + + for (i = 0; i < BPF_REG_SIZE; i++) { + state->stack[spi].slot_type[i] = STACK_DYNPTR; + state->stack[spi - 1].slot_type[i] = STACK_DYNPTR; + } + + type = arg_to_dynptr_type(arg_type); + if (type == BPF_DYNPTR_TYPE_INVALID) + return -EINVAL; + + mark_dynptr_stack_regs(env, &state->stack[spi].spilled_ptr, + &state->stack[spi - 1].spilled_ptr, type); + + if (dynptr_type_refcounted(type)) { + /* The id is used to track proper releasing */ + int id; + + if (clone_ref_obj_id) + id = clone_ref_obj_id; + else + id = acquire_reference_state(env, insn_idx); + + if (id < 0) + return id; + + state->stack[spi].spilled_ptr.ref_obj_id = id; + state->stack[spi - 1].spilled_ptr.ref_obj_id = id; + } + + state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN; + state->stack[spi - 1].spilled_ptr.live |= REG_LIVE_WRITTEN; + + return 0; +} + +static void invalidate_dynptr(struct bpf_verifier_env *env, struct bpf_func_state *state, int spi) +{ + int i; + + for (i = 0; i < BPF_REG_SIZE; i++) { + state->stack[spi].slot_type[i] = STACK_INVALID; + state->stack[spi - 1].slot_type[i] = STACK_INVALID; + } + + __mark_reg_not_init(env, &state->stack[spi].spilled_ptr); + __mark_reg_not_init(env, &state->stack[spi - 1].spilled_ptr); + + /* Why do we need to set REG_LIVE_WRITTEN for STACK_INVALID slot? + * + * While we don't allow reading STACK_INVALID, it is still possible to + * do <8 byte writes marking some but not all slots as STACK_MISC. Then, + * helpers or insns can do partial read of that part without failing, + * but check_stack_range_initialized, check_stack_read_var_off, and + * check_stack_read_fixed_off will do mark_reg_read for all 8-bytes of + * the slot conservatively. Hence we need to prevent those liveness + * marking walks. + * + * This was not a problem before because STACK_INVALID is only set by + * default (where the default reg state has its reg->parent as NULL), or + * in clean_live_states after REG_LIVE_DONE (at which point + * mark_reg_read won't walk reg->parent chain), but not randomly during + * verifier state exploration (like we did above). Hence, for our case + * parentage chain will still be live (i.e. reg->parent may be + * non-NULL), while earlier reg->parent was NULL, so we need + * REG_LIVE_WRITTEN to screen off read marker propagation when it is + * done later on reads or by mark_dynptr_read as well to unnecessary + * mark registers in verifier state. + */ + state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN; + state->stack[spi - 1].spilled_ptr.live |= REG_LIVE_WRITTEN; +} + +static int unmark_stack_slots_dynptr(struct bpf_verifier_env *env, struct bpf_reg_state *reg) +{ + struct bpf_func_state *state = func(env, reg); + int spi, ref_obj_id, i; + + spi = dynptr_get_spi(env, reg); + if (spi < 0) + return spi; + + if (!dynptr_type_refcounted(state->stack[spi].spilled_ptr.dynptr.type)) { + invalidate_dynptr(env, state, spi); + return 0; + } + + ref_obj_id = state->stack[spi].spilled_ptr.ref_obj_id; + + /* If the dynptr has a ref_obj_id, then we need to invalidate + * two things: + * + * 1) Any dynptrs with a matching ref_obj_id (clones) + * 2) Any slices derived from this dynptr. + */ + + /* Invalidate any slices associated with this dynptr */ + WARN_ON_ONCE(release_reference(env, ref_obj_id)); + + /* Invalidate any dynptr clones */ + for (i = 1; i < state->allocated_stack / BPF_REG_SIZE; i++) { + if (state->stack[i].spilled_ptr.ref_obj_id != ref_obj_id) + continue; + + /* it should always be the case that if the ref obj id + * matches then the stack slot also belongs to a + * dynptr + */ + if (state->stack[i].slot_type[0] != STACK_DYNPTR) { + verbose(env, "verifier internal error: misconfigured ref_obj_id\n"); + return -EFAULT; + } + if (state->stack[i].spilled_ptr.dynptr.first_slot) + invalidate_dynptr(env, state, i); + } + + return 0; +} + +static void __mark_reg_unknown(const struct bpf_verifier_env *env, + struct bpf_reg_state *reg); + +static void mark_reg_invalid(const struct bpf_verifier_env *env, struct bpf_reg_state *reg) +{ + if (!env->allow_ptr_leaks) + __mark_reg_not_init(env, reg); + else + __mark_reg_unknown(env, reg); +} + +static int destroy_if_dynptr_stack_slot(struct bpf_verifier_env *env, + struct bpf_func_state *state, int spi) +{ + struct bpf_func_state *fstate; + struct bpf_reg_state *dreg; + int i, dynptr_id; + + /* We always ensure that STACK_DYNPTR is never set partially, + * hence just checking for slot_type[0] is enough. This is + * different for STACK_SPILL, where it may be only set for + * 1 byte, so code has to use is_spilled_reg. + */ + if (state->stack[spi].slot_type[0] != STACK_DYNPTR) + return 0; + + /* Reposition spi to first slot */ + if (!state->stack[spi].spilled_ptr.dynptr.first_slot) + spi = spi + 1; + + if (dynptr_type_refcounted(state->stack[spi].spilled_ptr.dynptr.type)) { + verbose(env, "cannot overwrite referenced dynptr\n"); + return -EINVAL; + } + + mark_stack_slot_scratched(env, spi); + mark_stack_slot_scratched(env, spi - 1); + + /* Writing partially to one dynptr stack slot destroys both. */ + for (i = 0; i < BPF_REG_SIZE; i++) { + state->stack[spi].slot_type[i] = STACK_INVALID; + state->stack[spi - 1].slot_type[i] = STACK_INVALID; + } + + dynptr_id = state->stack[spi].spilled_ptr.id; + /* Invalidate any slices associated with this dynptr */ + bpf_for_each_reg_in_vstate(env->cur_state, fstate, dreg, ({ + /* Dynptr slices are only PTR_TO_MEM_OR_NULL and PTR_TO_MEM */ + if (dreg->type != (PTR_TO_MEM | PTR_MAYBE_NULL) && dreg->type != PTR_TO_MEM) + continue; + if (dreg->dynptr_id == dynptr_id) + mark_reg_invalid(env, dreg); + })); + + /* Do not release reference state, we are destroying dynptr on stack, + * not using some helper to release it. Just reset register. + */ + __mark_reg_not_init(env, &state->stack[spi].spilled_ptr); + __mark_reg_not_init(env, &state->stack[spi - 1].spilled_ptr); + + /* Same reason as unmark_stack_slots_dynptr above */ + state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN; + state->stack[spi - 1].spilled_ptr.live |= REG_LIVE_WRITTEN; + + return 0; +} + +static bool is_dynptr_reg_valid_uninit(struct bpf_verifier_env *env, struct bpf_reg_state *reg) +{ + int spi; + + if (reg->type == CONST_PTR_TO_DYNPTR) + return false; + + spi = dynptr_get_spi(env, reg); + + /* -ERANGE (i.e. spi not falling into allocated stack slots) isn't an + * error because this just means the stack state hasn't been updated yet. + * We will do check_mem_access to check and update stack bounds later. + */ + if (spi < 0 && spi != -ERANGE) + return false; + + /* We don't need to check if the stack slots are marked by previous + * dynptr initializations because we allow overwriting existing unreferenced + * STACK_DYNPTR slots, see mark_stack_slots_dynptr which calls + * destroy_if_dynptr_stack_slot to ensure dynptr objects at the slots we are + * touching are completely destructed before we reinitialize them for a new + * one. For referenced ones, destroy_if_dynptr_stack_slot returns an error early + * instead of delaying it until the end where the user will get "Unreleased + * reference" error. + */ + return true; +} + +static bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env, struct bpf_reg_state *reg) +{ + struct bpf_func_state *state = func(env, reg); + int i, spi; + + /* This already represents first slot of initialized bpf_dynptr. + * + * CONST_PTR_TO_DYNPTR already has fixed and var_off as 0 due to + * check_func_arg_reg_off's logic, so we don't need to check its + * offset and alignment. + */ + if (reg->type == CONST_PTR_TO_DYNPTR) + return true; + + spi = dynptr_get_spi(env, reg); + if (spi < 0) + return false; + if (!state->stack[spi].spilled_ptr.dynptr.first_slot) + return false; + + for (i = 0; i < BPF_REG_SIZE; i++) { + if (state->stack[spi].slot_type[i] != STACK_DYNPTR || + state->stack[spi - 1].slot_type[i] != STACK_DYNPTR) + return false; + } + + return true; +} + +static bool is_dynptr_type_expected(struct bpf_verifier_env *env, struct bpf_reg_state *reg, + enum bpf_arg_type arg_type) +{ + struct bpf_func_state *state = func(env, reg); + enum bpf_dynptr_type dynptr_type; + int spi; + + /* ARG_PTR_TO_DYNPTR takes any type of dynptr */ + if (arg_type == ARG_PTR_TO_DYNPTR) + return true; + + dynptr_type = arg_to_dynptr_type(arg_type); + if (reg->type == CONST_PTR_TO_DYNPTR) { + return reg->dynptr.type == dynptr_type; + } else { + spi = dynptr_get_spi(env, reg); + if (spi < 0) + return false; + return state->stack[spi].spilled_ptr.dynptr.type == dynptr_type; + } +} + +static void __mark_reg_known_zero(struct bpf_reg_state *reg); + +static int mark_stack_slots_iter(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, int insn_idx, + struct btf *btf, u32 btf_id, int nr_slots) +{ + struct bpf_func_state *state = func(env, reg); + int spi, i, j, id; + + spi = iter_get_spi(env, reg, nr_slots); + if (spi < 0) + return spi; + + id = acquire_reference_state(env, insn_idx); + if (id < 0) + return id; + + for (i = 0; i < nr_slots; i++) { + struct bpf_stack_state *slot = &state->stack[spi - i]; + struct bpf_reg_state *st = &slot->spilled_ptr; + + __mark_reg_known_zero(st); + st->type = PTR_TO_STACK; /* we don't have dedicated reg type */ + st->live |= REG_LIVE_WRITTEN; + st->ref_obj_id = i == 0 ? id : 0; + st->iter.btf = btf; + st->iter.btf_id = btf_id; + st->iter.state = BPF_ITER_STATE_ACTIVE; + st->iter.depth = 0; + + for (j = 0; j < BPF_REG_SIZE; j++) + slot->slot_type[j] = STACK_ITER; + + mark_stack_slot_scratched(env, spi - i); + } + + return 0; +} + +static int unmark_stack_slots_iter(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, int nr_slots) +{ + struct bpf_func_state *state = func(env, reg); + int spi, i, j; + + spi = iter_get_spi(env, reg, nr_slots); + if (spi < 0) + return spi; + + for (i = 0; i < nr_slots; i++) { + struct bpf_stack_state *slot = &state->stack[spi - i]; + struct bpf_reg_state *st = &slot->spilled_ptr; + + if (i == 0) + WARN_ON_ONCE(release_reference(env, st->ref_obj_id)); + + __mark_reg_not_init(env, st); + + /* see unmark_stack_slots_dynptr() for why we need to set REG_LIVE_WRITTEN */ + st->live |= REG_LIVE_WRITTEN; + + for (j = 0; j < BPF_REG_SIZE; j++) + slot->slot_type[j] = STACK_INVALID; + + mark_stack_slot_scratched(env, spi - i); + } + + return 0; +} + +static bool is_iter_reg_valid_uninit(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, int nr_slots) +{ + struct bpf_func_state *state = func(env, reg); + int spi, i, j; + + /* For -ERANGE (i.e. spi not falling into allocated stack slots), we + * will do check_mem_access to check and update stack bounds later, so + * return true for that case. + */ + spi = iter_get_spi(env, reg, nr_slots); + if (spi == -ERANGE) + return true; + if (spi < 0) + return false; + + for (i = 0; i < nr_slots; i++) { + struct bpf_stack_state *slot = &state->stack[spi - i]; + + for (j = 0; j < BPF_REG_SIZE; j++) + if (slot->slot_type[j] == STACK_ITER) + return false; + } + + return true; +} + +static bool is_iter_reg_valid_init(struct bpf_verifier_env *env, struct bpf_reg_state *reg, + struct btf *btf, u32 btf_id, int nr_slots) +{ + struct bpf_func_state *state = func(env, reg); + int spi, i, j; + + spi = iter_get_spi(env, reg, nr_slots); + if (spi < 0) + return false; + + for (i = 0; i < nr_slots; i++) { + struct bpf_stack_state *slot = &state->stack[spi - i]; + struct bpf_reg_state *st = &slot->spilled_ptr; + + /* only main (first) slot has ref_obj_id set */ + if (i == 0 && !st->ref_obj_id) + return false; + if (i != 0 && st->ref_obj_id) + return false; + if (st->iter.btf != btf || st->iter.btf_id != btf_id) + return false; + + for (j = 0; j < BPF_REG_SIZE; j++) + if (slot->slot_type[j] != STACK_ITER) + return false; + } + + return true; +} + +/* Check if given stack slot is "special": + * - spilled register state (STACK_SPILL); + * - dynptr state (STACK_DYNPTR); + * - iter state (STACK_ITER). + */ +static bool is_stack_slot_special(const struct bpf_stack_state *stack) +{ + enum bpf_stack_slot_type type = stack->slot_type[BPF_REG_SIZE - 1]; + + switch (type) { + case STACK_SPILL: + case STACK_DYNPTR: + case STACK_ITER: + return true; + case STACK_INVALID: + case STACK_MISC: + case STACK_ZERO: + return false; + default: + WARN_ONCE(1, "unknown stack slot type %d\n", type); + return true; + } +} + +/* The reg state of a pointer or a bounded scalar was saved when + * it was spilled to the stack. + */ +static bool is_spilled_reg(const struct bpf_stack_state *stack) +{ + return stack->slot_type[BPF_REG_SIZE - 1] == STACK_SPILL; +} + +static bool is_spilled_scalar_reg(const struct bpf_stack_state *stack) +{ + return stack->slot_type[BPF_REG_SIZE - 1] == STACK_SPILL && + stack->spilled_ptr.type == SCALAR_VALUE; +} + +static void scrub_spilled_slot(u8 *stype) +{ + if (*stype != STACK_INVALID) + *stype = STACK_MISC; +} + +static void print_verifier_state(struct bpf_verifier_env *env, + const struct bpf_func_state *state, + bool print_all) +{ + const struct bpf_reg_state *reg; + enum bpf_reg_type t; + int i; + + if (state->frameno) + verbose(env, " frame%d:", state->frameno); + for (i = 0; i < MAX_BPF_REG; i++) { + reg = &state->regs[i]; + t = reg->type; + if (t == NOT_INIT) + continue; + if (!print_all && !reg_scratched(env, i)) + continue; + verbose(env, " R%d", i); + print_liveness(env, reg->live); + verbose(env, "="); + if (t == SCALAR_VALUE && reg->precise) + verbose(env, "P"); + if ((t == SCALAR_VALUE || t == PTR_TO_STACK) && + tnum_is_const(reg->var_off)) { + /* reg->off should be 0 for SCALAR_VALUE */ + verbose(env, "%s", t == SCALAR_VALUE ? "" : reg_type_str(env, t)); + verbose(env, "%lld", reg->var_off.value + reg->off); + } else { + const char *sep = ""; + + verbose(env, "%s", reg_type_str(env, t)); + if (base_type(t) == PTR_TO_BTF_ID) + verbose(env, "%s", btf_type_name(reg->btf, reg->btf_id)); + verbose(env, "("); +/* + * _a stands for append, was shortened to avoid multiline statements below. + * This macro is used to output a comma separated list of attributes. + */ +#define verbose_a(fmt, ...) ({ verbose(env, "%s" fmt, sep, __VA_ARGS__); sep = ","; }) + + if (reg->id) + verbose_a("id=%d", reg->id); + if (reg->ref_obj_id) + verbose_a("ref_obj_id=%d", reg->ref_obj_id); + if (type_is_non_owning_ref(reg->type)) + verbose_a("%s", "non_own_ref"); + if (t != SCALAR_VALUE) + verbose_a("off=%d", reg->off); + if (type_is_pkt_pointer(t)) + verbose_a("r=%d", reg->range); + else if (base_type(t) == CONST_PTR_TO_MAP || + base_type(t) == PTR_TO_MAP_KEY || + base_type(t) == PTR_TO_MAP_VALUE) + verbose_a("ks=%d,vs=%d", + reg->map_ptr->key_size, + reg->map_ptr->value_size); + if (tnum_is_const(reg->var_off)) { + /* Typically an immediate SCALAR_VALUE, but + * could be a pointer whose offset is too big + * for reg->off + */ + verbose_a("imm=%llx", reg->var_off.value); + } else { + if (reg->smin_value != reg->umin_value && + reg->smin_value != S64_MIN) + verbose_a("smin=%lld", (long long)reg->smin_value); + if (reg->smax_value != reg->umax_value && + reg->smax_value != S64_MAX) + verbose_a("smax=%lld", (long long)reg->smax_value); + if (reg->umin_value != 0) + verbose_a("umin=%llu", (unsigned long long)reg->umin_value); + if (reg->umax_value != U64_MAX) + verbose_a("umax=%llu", (unsigned long long)reg->umax_value); + if (!tnum_is_unknown(reg->var_off)) { + char tn_buf[48]; + + tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); + verbose_a("var_off=%s", tn_buf); + } + if (reg->s32_min_value != reg->smin_value && + reg->s32_min_value != S32_MIN) + verbose_a("s32_min=%d", (int)(reg->s32_min_value)); + if (reg->s32_max_value != reg->smax_value && + reg->s32_max_value != S32_MAX) + verbose_a("s32_max=%d", (int)(reg->s32_max_value)); + if (reg->u32_min_value != reg->umin_value && + reg->u32_min_value != U32_MIN) + verbose_a("u32_min=%d", (int)(reg->u32_min_value)); + if (reg->u32_max_value != reg->umax_value && + reg->u32_max_value != U32_MAX) + verbose_a("u32_max=%d", (int)(reg->u32_max_value)); + } +#undef verbose_a + + verbose(env, ")"); + } + } + for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) { + char types_buf[BPF_REG_SIZE + 1]; + bool valid = false; + int j; + + for (j = 0; j < BPF_REG_SIZE; j++) { + if (state->stack[i].slot_type[j] != STACK_INVALID) + valid = true; + types_buf[j] = slot_type_char[state->stack[i].slot_type[j]]; + } + types_buf[BPF_REG_SIZE] = 0; + if (!valid) + continue; + if (!print_all && !stack_slot_scratched(env, i)) + continue; + switch (state->stack[i].slot_type[BPF_REG_SIZE - 1]) { + case STACK_SPILL: + reg = &state->stack[i].spilled_ptr; + t = reg->type; + + verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE); + print_liveness(env, reg->live); + verbose(env, "=%s", t == SCALAR_VALUE ? "" : reg_type_str(env, t)); + if (t == SCALAR_VALUE && reg->precise) + verbose(env, "P"); + if (t == SCALAR_VALUE && tnum_is_const(reg->var_off)) + verbose(env, "%lld", reg->var_off.value + reg->off); + break; + case STACK_DYNPTR: + i += BPF_DYNPTR_NR_SLOTS - 1; + reg = &state->stack[i].spilled_ptr; + + verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE); + print_liveness(env, reg->live); + verbose(env, "=dynptr_%s", dynptr_type_str(reg->dynptr.type)); + if (reg->ref_obj_id) + verbose(env, "(ref_id=%d)", reg->ref_obj_id); + break; + case STACK_ITER: + /* only main slot has ref_obj_id set; skip others */ + reg = &state->stack[i].spilled_ptr; + if (!reg->ref_obj_id) + continue; + + verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE); + print_liveness(env, reg->live); + verbose(env, "=iter_%s(ref_id=%d,state=%s,depth=%u)", + iter_type_str(reg->iter.btf, reg->iter.btf_id), + reg->ref_obj_id, iter_state_str(reg->iter.state), + reg->iter.depth); + break; + case STACK_MISC: + case STACK_ZERO: + default: + reg = &state->stack[i].spilled_ptr; + + for (j = 0; j < BPF_REG_SIZE; j++) + types_buf[j] = slot_type_char[state->stack[i].slot_type[j]]; + types_buf[BPF_REG_SIZE] = 0; + + verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE); + print_liveness(env, reg->live); + verbose(env, "=%s", types_buf); + break; + } + } + if (state->acquired_refs && state->refs[0].id) { + verbose(env, " refs=%d", state->refs[0].id); + for (i = 1; i < state->acquired_refs; i++) + if (state->refs[i].id) + verbose(env, ",%d", state->refs[i].id); + } + if (state->in_callback_fn) + verbose(env, " cb"); + if (state->in_async_callback_fn) + verbose(env, " async_cb"); + verbose(env, "\n"); + if (!print_all) + mark_verifier_state_clean(env); +} + +static inline u32 vlog_alignment(u32 pos) +{ + return round_up(max(pos + BPF_LOG_MIN_ALIGNMENT / 2, BPF_LOG_ALIGNMENT), + BPF_LOG_MIN_ALIGNMENT) - pos - 1; +} + +static void print_insn_state(struct bpf_verifier_env *env, + const struct bpf_func_state *state) +{ + if (env->prev_log_pos && env->prev_log_pos == env->log.end_pos) { + /* remove new line character */ + bpf_vlog_reset(&env->log, env->prev_log_pos - 1); + verbose(env, "%*c;", vlog_alignment(env->prev_insn_print_pos), ' '); + } else { + verbose(env, "%d:", env->insn_idx); + } + print_verifier_state(env, state, false); +} + +/* copy array src of length n * size bytes to dst. dst is reallocated if it's too + * small to hold src. This is different from krealloc since we don't want to preserve + * the contents of dst. + * + * Leaves dst untouched if src is NULL or length is zero. Returns NULL if memory could + * not be allocated. + */ +static void *copy_array(void *dst, const void *src, size_t n, size_t size, gfp_t flags) +{ + size_t alloc_bytes; + void *orig = dst; + size_t bytes; + + if (ZERO_OR_NULL_PTR(src)) + goto out; + + if (unlikely(check_mul_overflow(n, size, &bytes))) + return NULL; + + alloc_bytes = max(ksize(orig), kmalloc_size_roundup(bytes)); + dst = krealloc(orig, alloc_bytes, flags); + if (!dst) { + kfree(orig); + return NULL; + } + + memcpy(dst, src, bytes); +out: + return dst ? dst : ZERO_SIZE_PTR; +} + +/* resize an array from old_n items to new_n items. the array is reallocated if it's too + * small to hold new_n items. new items are zeroed out if the array grows. + * + * Contrary to krealloc_array, does not free arr if new_n is zero. + */ +static void *realloc_array(void *arr, size_t old_n, size_t new_n, size_t size) +{ + size_t alloc_size; + void *new_arr; + + if (!new_n || old_n == new_n) + goto out; + + alloc_size = kmalloc_size_roundup(size_mul(new_n, size)); + new_arr = krealloc(arr, alloc_size, GFP_KERNEL); + if (!new_arr) { + kfree(arr); + return NULL; + } + arr = new_arr; + + if (new_n > old_n) + memset(arr + old_n * size, 0, (new_n - old_n) * size); + +out: + return arr ? arr : ZERO_SIZE_PTR; +} + +static int copy_reference_state(struct bpf_func_state *dst, const struct bpf_func_state *src) +{ + dst->refs = copy_array(dst->refs, src->refs, src->acquired_refs, + sizeof(struct bpf_reference_state), GFP_KERNEL); + if (!dst->refs) + return -ENOMEM; + + dst->acquired_refs = src->acquired_refs; + return 0; +} + +static int copy_stack_state(struct bpf_func_state *dst, const struct bpf_func_state *src) +{ + size_t n = src->allocated_stack / BPF_REG_SIZE; + + dst->stack = copy_array(dst->stack, src->stack, n, sizeof(struct bpf_stack_state), + GFP_KERNEL); + if (!dst->stack) + return -ENOMEM; + + dst->allocated_stack = src->allocated_stack; + return 0; +} + +static int resize_reference_state(struct bpf_func_state *state, size_t n) +{ + state->refs = realloc_array(state->refs, state->acquired_refs, n, + sizeof(struct bpf_reference_state)); + if (!state->refs) + return -ENOMEM; + + state->acquired_refs = n; + return 0; +} + +/* Possibly update state->allocated_stack to be at least size bytes. Also + * possibly update the function's high-water mark in its bpf_subprog_info. + */ +static int grow_stack_state(struct bpf_verifier_env *env, struct bpf_func_state *state, int size) +{ + size_t old_n = state->allocated_stack / BPF_REG_SIZE, n = size / BPF_REG_SIZE; + + if (old_n >= n) + return 0; + + state->stack = realloc_array(state->stack, old_n, n, sizeof(struct bpf_stack_state)); + if (!state->stack) + return -ENOMEM; + + state->allocated_stack = size; + + /* update known max for given subprogram */ + if (env->subprog_info[state->subprogno].stack_depth < size) + env->subprog_info[state->subprogno].stack_depth = size; + + return 0; +} + +/* Acquire a pointer id from the env and update the state->refs to include + * this new pointer reference. + * On success, returns a valid pointer id to associate with the register + * On failure, returns a negative errno. + */ +static int acquire_reference_state(struct bpf_verifier_env *env, int insn_idx) +{ + struct bpf_func_state *state = cur_func(env); + int new_ofs = state->acquired_refs; + int id, err; + + err = resize_reference_state(state, state->acquired_refs + 1); + if (err) + return err; + id = ++env->id_gen; + state->refs[new_ofs].id = id; + state->refs[new_ofs].insn_idx = insn_idx; + state->refs[new_ofs].callback_ref = state->in_callback_fn ? state->frameno : 0; + + return id; +} + +/* release function corresponding to acquire_reference_state(). Idempotent. */ +static int release_reference_state(struct bpf_func_state *state, int ptr_id) +{ + int i, last_idx; + + last_idx = state->acquired_refs - 1; + for (i = 0; i < state->acquired_refs; i++) { + if (state->refs[i].id == ptr_id) { + /* Cannot release caller references in callbacks */ + if (state->in_callback_fn && state->refs[i].callback_ref != state->frameno) + return -EINVAL; + if (last_idx && i != last_idx) + memcpy(&state->refs[i], &state->refs[last_idx], + sizeof(*state->refs)); + memset(&state->refs[last_idx], 0, sizeof(*state->refs)); + state->acquired_refs--; + return 0; + } + } + return -EINVAL; +} + +static void free_func_state(struct bpf_func_state *state) +{ + if (!state) + return; + kfree(state->refs); + kfree(state->stack); + kfree(state); +} + +static void clear_jmp_history(struct bpf_verifier_state *state) +{ + kfree(state->jmp_history); + state->jmp_history = NULL; + state->jmp_history_cnt = 0; +} + +static void free_verifier_state(struct bpf_verifier_state *state, + bool free_self) +{ + int i; + + for (i = 0; i <= state->curframe; i++) { + free_func_state(state->frame[i]); + state->frame[i] = NULL; + } + clear_jmp_history(state); + if (free_self) + kfree(state); +} + +/* copy verifier state from src to dst growing dst stack space + * when necessary to accommodate larger src stack + */ +static int copy_func_state(struct bpf_func_state *dst, + const struct bpf_func_state *src) +{ + int err; + + memcpy(dst, src, offsetof(struct bpf_func_state, acquired_refs)); + err = copy_reference_state(dst, src); + if (err) + return err; + return copy_stack_state(dst, src); +} + +static int copy_verifier_state(struct bpf_verifier_state *dst_state, + const struct bpf_verifier_state *src) +{ + struct bpf_func_state *dst; + int i, err; + + dst_state->jmp_history = copy_array(dst_state->jmp_history, src->jmp_history, + src->jmp_history_cnt, sizeof(struct bpf_idx_pair), + GFP_USER); + if (!dst_state->jmp_history) + return -ENOMEM; + dst_state->jmp_history_cnt = src->jmp_history_cnt; + + /* if dst has more stack frames then src frame, free them */ + for (i = src->curframe + 1; i <= dst_state->curframe; i++) { + free_func_state(dst_state->frame[i]); + dst_state->frame[i] = NULL; + } + dst_state->speculative = src->speculative; + dst_state->active_rcu_lock = src->active_rcu_lock; + dst_state->curframe = src->curframe; + dst_state->active_lock.ptr = src->active_lock.ptr; + dst_state->active_lock.id = src->active_lock.id; + dst_state->branches = src->branches; + dst_state->parent = src->parent; + dst_state->first_insn_idx = src->first_insn_idx; + dst_state->last_insn_idx = src->last_insn_idx; + dst_state->dfs_depth = src->dfs_depth; + dst_state->callback_unroll_depth = src->callback_unroll_depth; + dst_state->used_as_loop_entry = src->used_as_loop_entry; + for (i = 0; i <= src->curframe; i++) { + dst = dst_state->frame[i]; + if (!dst) { + dst = kzalloc(sizeof(*dst), GFP_KERNEL); + if (!dst) + return -ENOMEM; + dst_state->frame[i] = dst; + } + err = copy_func_state(dst, src->frame[i]); + if (err) + return err; + } + return 0; +} + +static u32 state_htab_size(struct bpf_verifier_env *env) +{ + return env->prog->len; +} + +static struct bpf_verifier_state_list **explored_state(struct bpf_verifier_env *env, int idx) +{ + struct bpf_verifier_state *cur = env->cur_state; + struct bpf_func_state *state = cur->frame[cur->curframe]; + + return &env->explored_states[(idx ^ state->callsite) % state_htab_size(env)]; +} + +static bool same_callsites(struct bpf_verifier_state *a, struct bpf_verifier_state *b) +{ + int fr; + + if (a->curframe != b->curframe) + return false; + + for (fr = a->curframe; fr >= 0; fr--) + if (a->frame[fr]->callsite != b->frame[fr]->callsite) + return false; + + return true; +} + +/* Open coded iterators allow back-edges in the state graph in order to + * check unbounded loops that iterators. + * + * In is_state_visited() it is necessary to know if explored states are + * part of some loops in order to decide whether non-exact states + * comparison could be used: + * - non-exact states comparison establishes sub-state relation and uses + * read and precision marks to do so, these marks are propagated from + * children states and thus are not guaranteed to be final in a loop; + * - exact states comparison just checks if current and explored states + * are identical (and thus form a back-edge). + * + * Paper "A New Algorithm for Identifying Loops in Decompilation" + * by Tao Wei, Jian Mao, Wei Zou and Yu Chen [1] presents a convenient + * algorithm for loop structure detection and gives an overview of + * relevant terminology. It also has helpful illustrations. + * + * [1] https://api.semanticscholar.org/CorpusID:15784067 + * + * We use a similar algorithm but because loop nested structure is + * irrelevant for verifier ours is significantly simpler and resembles + * strongly connected components algorithm from Sedgewick's textbook. + * + * Define topmost loop entry as a first node of the loop traversed in a + * depth first search starting from initial state. The goal of the loop + * tracking algorithm is to associate topmost loop entries with states + * derived from these entries. + * + * For each step in the DFS states traversal algorithm needs to identify + * the following situations: + * + * initial initial initial + * | | | + * V V V + * ... ... .---------> hdr + * | | | | + * V V | V + * cur .-> succ | .------... + * | | | | | | + * V | V | V V + * succ '-- cur | ... ... + * | | | + * | V V + * | succ <- cur + * | | + * | V + * | ... + * | | + * '----' + * + * (A) successor state of cur (B) successor state of cur or it's entry + * not yet traversed are in current DFS path, thus cur and succ + * are members of the same outermost loop + * + * initial initial + * | | + * V V + * ... ... + * | | + * V V + * .------... .------... + * | | | | + * V V V V + * .-> hdr ... ... ... + * | | | | | + * | V V V V + * | succ <- cur succ <- cur + * | | | + * | V V + * | ... ... + * | | | + * '----' exit + * + * (C) successor state of cur is a part of some loop but this loop + * does not include cur or successor state is not in a loop at all. + * + * Algorithm could be described as the following python code: + * + * traversed = set() # Set of traversed nodes + * entries = {} # Mapping from node to loop entry + * depths = {} # Depth level assigned to graph node + * path = set() # Current DFS path + * + * # Find outermost loop entry known for n + * def get_loop_entry(n): + * h = entries.get(n, None) + * while h in entries and entries[h] != h: + * h = entries[h] + * return h + * + * # Update n's loop entry if h's outermost entry comes + * # before n's outermost entry in current DFS path. + * def update_loop_entry(n, h): + * n1 = get_loop_entry(n) or n + * h1 = get_loop_entry(h) or h + * if h1 in path and depths[h1] <= depths[n1]: + * entries[n] = h1 + * + * def dfs(n, depth): + * traversed.add(n) + * path.add(n) + * depths[n] = depth + * for succ in G.successors(n): + * if succ not in traversed: + * # Case A: explore succ and update cur's loop entry + * # only if succ's entry is in current DFS path. + * dfs(succ, depth + 1) + * h = get_loop_entry(succ) + * update_loop_entry(n, h) + * else: + * # Case B or C depending on `h1 in path` check in update_loop_entry(). + * update_loop_entry(n, succ) + * path.remove(n) + * + * To adapt this algorithm for use with verifier: + * - use st->branch == 0 as a signal that DFS of succ had been finished + * and cur's loop entry has to be updated (case A), handle this in + * update_branch_counts(); + * - use st->branch > 0 as a signal that st is in the current DFS path; + * - handle cases B and C in is_state_visited(); + * - update topmost loop entry for intermediate states in get_loop_entry(). + */ +static struct bpf_verifier_state *get_loop_entry(struct bpf_verifier_state *st) +{ + struct bpf_verifier_state *topmost = st->loop_entry, *old; + + while (topmost && topmost->loop_entry && topmost != topmost->loop_entry) + topmost = topmost->loop_entry; + /* Update loop entries for intermediate states to avoid this + * traversal in future get_loop_entry() calls. + */ + while (st && st->loop_entry != topmost) { + old = st->loop_entry; + st->loop_entry = topmost; + st = old; + } + return topmost; +} + +static void update_loop_entry(struct bpf_verifier_state *cur, struct bpf_verifier_state *hdr) +{ + struct bpf_verifier_state *cur1, *hdr1; + + cur1 = get_loop_entry(cur) ?: cur; + hdr1 = get_loop_entry(hdr) ?: hdr; + /* The head1->branches check decides between cases B and C in + * comment for get_loop_entry(). If hdr1->branches == 0 then + * head's topmost loop entry is not in current DFS path, + * hence 'cur' and 'hdr' are not in the same loop and there is + * no need to update cur->loop_entry. + */ + if (hdr1->branches && hdr1->dfs_depth <= cur1->dfs_depth) { + cur->loop_entry = hdr; + hdr->used_as_loop_entry = true; + } +} + +static void update_branch_counts(struct bpf_verifier_env *env, struct bpf_verifier_state *st) +{ + while (st) { + u32 br = --st->branches; + + /* br == 0 signals that DFS exploration for 'st' is finished, + * thus it is necessary to update parent's loop entry if it + * turned out that st is a part of some loop. + * This is a part of 'case A' in get_loop_entry() comment. + */ + if (br == 0 && st->parent && st->loop_entry) + update_loop_entry(st->parent, st->loop_entry); + + /* WARN_ON(br > 1) technically makes sense here, + * but see comment in push_stack(), hence: + */ + WARN_ONCE((int)br < 0, + "BUG update_branch_counts:branches_to_explore=%d\n", + br); + if (br) + break; + st = st->parent; + } +} + +static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx, + int *insn_idx, bool pop_log) +{ + struct bpf_verifier_state *cur = env->cur_state; + struct bpf_verifier_stack_elem *elem, *head = env->head; + int err; + + if (env->head == NULL) + return -ENOENT; + + if (cur) { + err = copy_verifier_state(cur, &head->st); + if (err) + return err; + } + if (pop_log) + bpf_vlog_reset(&env->log, head->log_pos); + if (insn_idx) + *insn_idx = head->insn_idx; + if (prev_insn_idx) + *prev_insn_idx = head->prev_insn_idx; + elem = head->next; + free_verifier_state(&head->st, false); + kfree(head); + env->head = elem; + env->stack_size--; + return 0; +} + +static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env, + int insn_idx, int prev_insn_idx, + bool speculative) +{ + struct bpf_verifier_state *cur = env->cur_state; + struct bpf_verifier_stack_elem *elem; + int err; + + elem = kzalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL); + if (!elem) + goto err; + + elem->insn_idx = insn_idx; + elem->prev_insn_idx = prev_insn_idx; + elem->next = env->head; + elem->log_pos = env->log.end_pos; + env->head = elem; + env->stack_size++; + err = copy_verifier_state(&elem->st, cur); + if (err) + goto err; + elem->st.speculative |= speculative; + if (env->stack_size > BPF_COMPLEXITY_LIMIT_JMP_SEQ) { + verbose(env, "The sequence of %d jumps is too complex.\n", + env->stack_size); + goto err; + } + if (elem->st.parent) { + ++elem->st.parent->branches; + /* WARN_ON(branches > 2) technically makes sense here, + * but + * 1. speculative states will bump 'branches' for non-branch + * instructions + * 2. is_state_visited() heuristics may decide not to create + * a new state for a sequence of branches and all such current + * and cloned states will be pointing to a single parent state + * which might have large 'branches' count. + */ + } + return &elem->st; +err: + free_verifier_state(env->cur_state, true); + env->cur_state = NULL; + /* pop all elements and return */ + while (!pop_stack(env, NULL, NULL, false)); + return NULL; +} + +#define CALLER_SAVED_REGS 6 +static const int caller_saved[CALLER_SAVED_REGS] = { + BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5 +}; + +/* This helper doesn't clear reg->id */ +static void ___mark_reg_known(struct bpf_reg_state *reg, u64 imm) +{ + reg->var_off = tnum_const(imm); + reg->smin_value = (s64)imm; + reg->smax_value = (s64)imm; + reg->umin_value = imm; + reg->umax_value = imm; + + reg->s32_min_value = (s32)imm; + reg->s32_max_value = (s32)imm; + reg->u32_min_value = (u32)imm; + reg->u32_max_value = (u32)imm; +} + +/* Mark the unknown part of a register (variable offset or scalar value) as + * known to have the value @imm. + */ +static void __mark_reg_known(struct bpf_reg_state *reg, u64 imm) +{ + /* Clear off and union(map_ptr, range) */ + memset(((u8 *)reg) + sizeof(reg->type), 0, + offsetof(struct bpf_reg_state, var_off) - sizeof(reg->type)); + reg->id = 0; + reg->ref_obj_id = 0; + ___mark_reg_known(reg, imm); +} + +static void __mark_reg32_known(struct bpf_reg_state *reg, u64 imm) +{ + reg->var_off = tnum_const_subreg(reg->var_off, imm); + reg->s32_min_value = (s32)imm; + reg->s32_max_value = (s32)imm; + reg->u32_min_value = (u32)imm; + reg->u32_max_value = (u32)imm; +} + +/* Mark the 'variable offset' part of a register as zero. This should be + * used only on registers holding a pointer type. + */ +static void __mark_reg_known_zero(struct bpf_reg_state *reg) +{ + __mark_reg_known(reg, 0); +} + +static void __mark_reg_const_zero(struct bpf_reg_state *reg) +{ + __mark_reg_known(reg, 0); + reg->type = SCALAR_VALUE; +} + +static void mark_reg_known_zero(struct bpf_verifier_env *env, + struct bpf_reg_state *regs, u32 regno) +{ + if (WARN_ON(regno >= MAX_BPF_REG)) { + verbose(env, "mark_reg_known_zero(regs, %u)\n", regno); + /* Something bad happened, let's kill all regs */ + for (regno = 0; regno < MAX_BPF_REG; regno++) + __mark_reg_not_init(env, regs + regno); + return; + } + __mark_reg_known_zero(regs + regno); +} + +static void __mark_dynptr_reg(struct bpf_reg_state *reg, enum bpf_dynptr_type type, + bool first_slot, int dynptr_id) +{ + /* reg->type has no meaning for STACK_DYNPTR, but when we set reg for + * callback arguments, it does need to be CONST_PTR_TO_DYNPTR, so simply + * set it unconditionally as it is ignored for STACK_DYNPTR anyway. + */ + __mark_reg_known_zero(reg); + reg->type = CONST_PTR_TO_DYNPTR; + /* Give each dynptr a unique id to uniquely associate slices to it. */ + reg->id = dynptr_id; + reg->dynptr.type = type; + reg->dynptr.first_slot = first_slot; +} + +static void mark_ptr_not_null_reg(struct bpf_reg_state *reg) +{ + if (base_type(reg->type) == PTR_TO_MAP_VALUE) { + const struct bpf_map *map = reg->map_ptr; + + if (map->inner_map_meta) { + reg->type = CONST_PTR_TO_MAP; + reg->map_ptr = map->inner_map_meta; + /* transfer reg's id which is unique for every map_lookup_elem + * as UID of the inner map. + */ + if (btf_record_has_field(map->inner_map_meta->record, BPF_TIMER)) + reg->map_uid = reg->id; + } else if (map->map_type == BPF_MAP_TYPE_XSKMAP) { + reg->type = PTR_TO_XDP_SOCK; + } else if (map->map_type == BPF_MAP_TYPE_SOCKMAP || + map->map_type == BPF_MAP_TYPE_SOCKHASH) { + reg->type = PTR_TO_SOCKET; + } else { + reg->type = PTR_TO_MAP_VALUE; + } + return; + } + + reg->type &= ~PTR_MAYBE_NULL; +} + +static void mark_reg_graph_node(struct bpf_reg_state *regs, u32 regno, + struct btf_field_graph_root *ds_head) +{ + __mark_reg_known_zero(®s[regno]); + regs[regno].type = PTR_TO_BTF_ID | MEM_ALLOC; + regs[regno].btf = ds_head->btf; + regs[regno].btf_id = ds_head->value_btf_id; + regs[regno].off = ds_head->node_offset; +} + +static bool reg_is_pkt_pointer(const struct bpf_reg_state *reg) +{ + return type_is_pkt_pointer(reg->type); +} + +static bool reg_is_pkt_pointer_any(const struct bpf_reg_state *reg) +{ + return reg_is_pkt_pointer(reg) || + reg->type == PTR_TO_PACKET_END; +} + +static bool reg_is_dynptr_slice_pkt(const struct bpf_reg_state *reg) +{ + return base_type(reg->type) == PTR_TO_MEM && + (reg->type & DYNPTR_TYPE_SKB || reg->type & DYNPTR_TYPE_XDP); +} + +/* Unmodified PTR_TO_PACKET[_META,_END] register from ctx access. */ +static bool reg_is_init_pkt_pointer(const struct bpf_reg_state *reg, + enum bpf_reg_type which) +{ + /* The register can already have a range from prior markings. + * This is fine as long as it hasn't been advanced from its + * origin. + */ + return reg->type == which && + reg->id == 0 && + reg->off == 0 && + tnum_equals_const(reg->var_off, 0); +} + +/* Reset the min/max bounds of a register */ +static void __mark_reg_unbounded(struct bpf_reg_state *reg) +{ + reg->smin_value = S64_MIN; + reg->smax_value = S64_MAX; + reg->umin_value = 0; + reg->umax_value = U64_MAX; + + reg->s32_min_value = S32_MIN; + reg->s32_max_value = S32_MAX; + reg->u32_min_value = 0; + reg->u32_max_value = U32_MAX; +} + +static void __mark_reg64_unbounded(struct bpf_reg_state *reg) +{ + reg->smin_value = S64_MIN; + reg->smax_value = S64_MAX; + reg->umin_value = 0; + reg->umax_value = U64_MAX; +} + +static void __mark_reg32_unbounded(struct bpf_reg_state *reg) +{ + reg->s32_min_value = S32_MIN; + reg->s32_max_value = S32_MAX; + reg->u32_min_value = 0; + reg->u32_max_value = U32_MAX; +} + +static void __update_reg32_bounds(struct bpf_reg_state *reg) +{ + struct tnum var32_off = tnum_subreg(reg->var_off); + + /* min signed is max(sign bit) | min(other bits) */ + reg->s32_min_value = max_t(s32, reg->s32_min_value, + var32_off.value | (var32_off.mask & S32_MIN)); + /* max signed is min(sign bit) | max(other bits) */ + reg->s32_max_value = min_t(s32, reg->s32_max_value, + var32_off.value | (var32_off.mask & S32_MAX)); + reg->u32_min_value = max_t(u32, reg->u32_min_value, (u32)var32_off.value); + reg->u32_max_value = min(reg->u32_max_value, + (u32)(var32_off.value | var32_off.mask)); +} + +static void __update_reg64_bounds(struct bpf_reg_state *reg) +{ + /* min signed is max(sign bit) | min(other bits) */ + reg->smin_value = max_t(s64, reg->smin_value, + reg->var_off.value | (reg->var_off.mask & S64_MIN)); + /* max signed is min(sign bit) | max(other bits) */ + reg->smax_value = min_t(s64, reg->smax_value, + reg->var_off.value | (reg->var_off.mask & S64_MAX)); + reg->umin_value = max(reg->umin_value, reg->var_off.value); + reg->umax_value = min(reg->umax_value, + reg->var_off.value | reg->var_off.mask); +} + +static void __update_reg_bounds(struct bpf_reg_state *reg) +{ + __update_reg32_bounds(reg); + __update_reg64_bounds(reg); +} + +/* Uses signed min/max values to inform unsigned, and vice-versa */ +static void __reg32_deduce_bounds(struct bpf_reg_state *reg) +{ + /* Learn sign from signed bounds. + * If we cannot cross the sign boundary, then signed and unsigned bounds + * are the same, so combine. This works even in the negative case, e.g. + * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff. + */ + if (reg->s32_min_value >= 0 || reg->s32_max_value < 0) { + reg->s32_min_value = reg->u32_min_value = + max_t(u32, reg->s32_min_value, reg->u32_min_value); + reg->s32_max_value = reg->u32_max_value = + min_t(u32, reg->s32_max_value, reg->u32_max_value); + return; + } + /* Learn sign from unsigned bounds. Signed bounds cross the sign + * boundary, so we must be careful. + */ + if ((s32)reg->u32_max_value >= 0) { + /* Positive. We can't learn anything from the smin, but smax + * is positive, hence safe. + */ + reg->s32_min_value = reg->u32_min_value; + reg->s32_max_value = reg->u32_max_value = + min_t(u32, reg->s32_max_value, reg->u32_max_value); + } else if ((s32)reg->u32_min_value < 0) { + /* Negative. We can't learn anything from the smax, but smin + * is negative, hence safe. + */ + reg->s32_min_value = reg->u32_min_value = + max_t(u32, reg->s32_min_value, reg->u32_min_value); + reg->s32_max_value = reg->u32_max_value; + } +} + +static void __reg64_deduce_bounds(struct bpf_reg_state *reg) +{ + /* Learn sign from signed bounds. + * If we cannot cross the sign boundary, then signed and unsigned bounds + * are the same, so combine. This works even in the negative case, e.g. + * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff. + */ + if (reg->smin_value >= 0 || reg->smax_value < 0) { + reg->smin_value = reg->umin_value = max_t(u64, reg->smin_value, + reg->umin_value); + reg->smax_value = reg->umax_value = min_t(u64, reg->smax_value, + reg->umax_value); + return; + } + /* Learn sign from unsigned bounds. Signed bounds cross the sign + * boundary, so we must be careful. + */ + if ((s64)reg->umax_value >= 0) { + /* Positive. We can't learn anything from the smin, but smax + * is positive, hence safe. + */ + reg->smin_value = reg->umin_value; + reg->smax_value = reg->umax_value = min_t(u64, reg->smax_value, + reg->umax_value); + } else if ((s64)reg->umin_value < 0) { + /* Negative. We can't learn anything from the smax, but smin + * is negative, hence safe. + */ + reg->smin_value = reg->umin_value = max_t(u64, reg->smin_value, + reg->umin_value); + reg->smax_value = reg->umax_value; + } +} + +static void __reg_deduce_bounds(struct bpf_reg_state *reg) +{ + __reg32_deduce_bounds(reg); + __reg64_deduce_bounds(reg); +} + +/* Attempts to improve var_off based on unsigned min/max information */ +static void __reg_bound_offset(struct bpf_reg_state *reg) +{ + struct tnum var64_off = tnum_intersect(reg->var_off, + tnum_range(reg->umin_value, + reg->umax_value)); + struct tnum var32_off = tnum_intersect(tnum_subreg(var64_off), + tnum_range(reg->u32_min_value, + reg->u32_max_value)); + + reg->var_off = tnum_or(tnum_clear_subreg(var64_off), var32_off); +} + +static void reg_bounds_sync(struct bpf_reg_state *reg) +{ + /* We might have learned new bounds from the var_off. */ + __update_reg_bounds(reg); + /* We might have learned something about the sign bit. */ + __reg_deduce_bounds(reg); + /* We might have learned some bits from the bounds. */ + __reg_bound_offset(reg); + /* Intersecting with the old var_off might have improved our bounds + * slightly, e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc), + * then new var_off is (0; 0x7f...fc) which improves our umax. + */ + __update_reg_bounds(reg); +} + +static bool __reg32_bound_s64(s32 a) +{ + return a >= 0 && a <= S32_MAX; +} + +static void __reg_assign_32_into_64(struct bpf_reg_state *reg) +{ + reg->umin_value = reg->u32_min_value; + reg->umax_value = reg->u32_max_value; + + /* Attempt to pull 32-bit signed bounds into 64-bit bounds but must + * be positive otherwise set to worse case bounds and refine later + * from tnum. + */ + if (__reg32_bound_s64(reg->s32_min_value) && + __reg32_bound_s64(reg->s32_max_value)) { + reg->smin_value = reg->s32_min_value; + reg->smax_value = reg->s32_max_value; + } else { + reg->smin_value = 0; + reg->smax_value = U32_MAX; + } +} + +static void __reg_combine_32_into_64(struct bpf_reg_state *reg) +{ + /* special case when 64-bit register has upper 32-bit register + * zeroed. Typically happens after zext or <<32, >>32 sequence + * allowing us to use 32-bit bounds directly, + */ + if (tnum_equals_const(tnum_clear_subreg(reg->var_off), 0)) { + __reg_assign_32_into_64(reg); + } else { + /* Otherwise the best we can do is push lower 32bit known and + * unknown bits into register (var_off set from jmp logic) + * then learn as much as possible from the 64-bit tnum + * known and unknown bits. The previous smin/smax bounds are + * invalid here because of jmp32 compare so mark them unknown + * so they do not impact tnum bounds calculation. + */ + __mark_reg64_unbounded(reg); + } + reg_bounds_sync(reg); +} + +static bool __reg64_bound_s32(s64 a) +{ + return a >= S32_MIN && a <= S32_MAX; +} + +static bool __reg64_bound_u32(u64 a) +{ + return a >= U32_MIN && a <= U32_MAX; +} + +static void __reg_combine_64_into_32(struct bpf_reg_state *reg) +{ + __mark_reg32_unbounded(reg); + if (__reg64_bound_s32(reg->smin_value) && __reg64_bound_s32(reg->smax_value)) { + reg->s32_min_value = (s32)reg->smin_value; + reg->s32_max_value = (s32)reg->smax_value; + } + if (__reg64_bound_u32(reg->umin_value) && __reg64_bound_u32(reg->umax_value)) { + reg->u32_min_value = (u32)reg->umin_value; + reg->u32_max_value = (u32)reg->umax_value; + } + reg_bounds_sync(reg); +} + +/* Mark a register as having a completely unknown (scalar) value. */ +static void __mark_reg_unknown(const struct bpf_verifier_env *env, + struct bpf_reg_state *reg) +{ + /* + * Clear type, off, and union(map_ptr, range) and + * padding between 'type' and union + */ + memset(reg, 0, offsetof(struct bpf_reg_state, var_off)); + reg->type = SCALAR_VALUE; + reg->id = 0; + reg->ref_obj_id = 0; + reg->var_off = tnum_unknown; + reg->frameno = 0; + reg->precise = !env->bpf_capable; + __mark_reg_unbounded(reg); +} + +static void mark_reg_unknown(struct bpf_verifier_env *env, + struct bpf_reg_state *regs, u32 regno) +{ + if (WARN_ON(regno >= MAX_BPF_REG)) { + verbose(env, "mark_reg_unknown(regs, %u)\n", regno); + /* Something bad happened, let's kill all regs except FP */ + for (regno = 0; regno < BPF_REG_FP; regno++) + __mark_reg_not_init(env, regs + regno); + return; + } + __mark_reg_unknown(env, regs + regno); +} + +static void __mark_reg_not_init(const struct bpf_verifier_env *env, + struct bpf_reg_state *reg) +{ + __mark_reg_unknown(env, reg); + reg->type = NOT_INIT; +} + +static void mark_reg_not_init(struct bpf_verifier_env *env, + struct bpf_reg_state *regs, u32 regno) +{ + if (WARN_ON(regno >= MAX_BPF_REG)) { + verbose(env, "mark_reg_not_init(regs, %u)\n", regno); + /* Something bad happened, let's kill all regs except FP */ + for (regno = 0; regno < BPF_REG_FP; regno++) + __mark_reg_not_init(env, regs + regno); + return; + } + __mark_reg_not_init(env, regs + regno); +} + +static void mark_btf_ld_reg(struct bpf_verifier_env *env, + struct bpf_reg_state *regs, u32 regno, + enum bpf_reg_type reg_type, + struct btf *btf, u32 btf_id, + enum bpf_type_flag flag) +{ + if (reg_type == SCALAR_VALUE) { + mark_reg_unknown(env, regs, regno); + return; + } + mark_reg_known_zero(env, regs, regno); + regs[regno].type = PTR_TO_BTF_ID | flag; + regs[regno].btf = btf; + regs[regno].btf_id = btf_id; +} + +#define DEF_NOT_SUBREG (0) +static void init_reg_state(struct bpf_verifier_env *env, + struct bpf_func_state *state) +{ + struct bpf_reg_state *regs = state->regs; + int i; + + for (i = 0; i < MAX_BPF_REG; i++) { + mark_reg_not_init(env, regs, i); + regs[i].live = REG_LIVE_NONE; + regs[i].parent = NULL; + regs[i].subreg_def = DEF_NOT_SUBREG; + } + + /* frame pointer */ + regs[BPF_REG_FP].type = PTR_TO_STACK; + mark_reg_known_zero(env, regs, BPF_REG_FP); + regs[BPF_REG_FP].frameno = state->frameno; +} + +#define BPF_MAIN_FUNC (-1) +static void init_func_state(struct bpf_verifier_env *env, + struct bpf_func_state *state, + int callsite, int frameno, int subprogno) +{ + state->callsite = callsite; + state->frameno = frameno; + state->subprogno = subprogno; + state->callback_ret_range = tnum_range(0, 0); + init_reg_state(env, state); + mark_verifier_state_scratched(env); +} + +/* Similar to push_stack(), but for async callbacks */ +static struct bpf_verifier_state *push_async_cb(struct bpf_verifier_env *env, + int insn_idx, int prev_insn_idx, + int subprog) +{ + struct bpf_verifier_stack_elem *elem; + struct bpf_func_state *frame; + + elem = kzalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL); + if (!elem) + goto err; + + elem->insn_idx = insn_idx; + elem->prev_insn_idx = prev_insn_idx; + elem->next = env->head; + elem->log_pos = env->log.end_pos; + env->head = elem; + env->stack_size++; + if (env->stack_size > BPF_COMPLEXITY_LIMIT_JMP_SEQ) { + verbose(env, + "The sequence of %d jumps is too complex for async cb.\n", + env->stack_size); + goto err; + } + /* Unlike push_stack() do not copy_verifier_state(). + * The caller state doesn't matter. + * This is async callback. It starts in a fresh stack. + * Initialize it similar to do_check_common(). + */ + elem->st.branches = 1; + frame = kzalloc(sizeof(*frame), GFP_KERNEL); + if (!frame) + goto err; + init_func_state(env, frame, + BPF_MAIN_FUNC /* callsite */, + 0 /* frameno within this callchain */, + subprog /* subprog number within this prog */); + elem->st.frame[0] = frame; + return &elem->st; +err: + free_verifier_state(env->cur_state, true); + env->cur_state = NULL; + /* pop all elements and return */ + while (!pop_stack(env, NULL, NULL, false)); + return NULL; +} + + +enum reg_arg_type { + SRC_OP, /* register is used as source operand */ + DST_OP, /* register is used as destination operand */ + DST_OP_NO_MARK /* same as above, check only, don't mark */ +}; + +static int cmp_subprogs(const void *a, const void *b) +{ + return ((struct bpf_subprog_info *)a)->start - + ((struct bpf_subprog_info *)b)->start; +} + +static int find_subprog(struct bpf_verifier_env *env, int off) +{ + struct bpf_subprog_info *p; + + p = bsearch(&off, env->subprog_info, env->subprog_cnt, + sizeof(env->subprog_info[0]), cmp_subprogs); + if (!p) + return -ENOENT; + return p - env->subprog_info; + +} + +static int add_subprog(struct bpf_verifier_env *env, int off) +{ + int insn_cnt = env->prog->len; + int ret; + + if (off >= insn_cnt || off < 0) { + verbose(env, "call to invalid destination\n"); + return -EINVAL; + } + ret = find_subprog(env, off); + if (ret >= 0) + return ret; + if (env->subprog_cnt >= BPF_MAX_SUBPROGS) { + verbose(env, "too many subprograms\n"); + return -E2BIG; + } + /* determine subprog starts. The end is one before the next starts */ + env->subprog_info[env->subprog_cnt++].start = off; + sort(env->subprog_info, env->subprog_cnt, + sizeof(env->subprog_info[0]), cmp_subprogs, NULL); + return env->subprog_cnt - 1; +} + +#define MAX_KFUNC_DESCS 256 +#define MAX_KFUNC_BTFS 256 + +struct bpf_kfunc_desc { + struct btf_func_model func_model; + u32 func_id; + s32 imm; + u16 offset; + unsigned long addr; +}; + +struct bpf_kfunc_btf { + struct btf *btf; + struct module *module; + u16 offset; +}; + +struct bpf_kfunc_desc_tab { + /* Sorted by func_id (BTF ID) and offset (fd_array offset) during + * verification. JITs do lookups by bpf_insn, where func_id may not be + * available, therefore at the end of verification do_misc_fixups() + * sorts this by imm and offset. + */ + struct bpf_kfunc_desc descs[MAX_KFUNC_DESCS]; + u32 nr_descs; +}; + +struct bpf_kfunc_btf_tab { + struct bpf_kfunc_btf descs[MAX_KFUNC_BTFS]; + u32 nr_descs; +}; + +static int kfunc_desc_cmp_by_id_off(const void *a, const void *b) +{ + const struct bpf_kfunc_desc *d0 = a; + const struct bpf_kfunc_desc *d1 = b; + + /* func_id is not greater than BTF_MAX_TYPE */ + return d0->func_id - d1->func_id ?: d0->offset - d1->offset; +} + +static int kfunc_btf_cmp_by_off(const void *a, const void *b) +{ + const struct bpf_kfunc_btf *d0 = a; + const struct bpf_kfunc_btf *d1 = b; + + return d0->offset - d1->offset; +} + +static const struct bpf_kfunc_desc * +find_kfunc_desc(const struct bpf_prog *prog, u32 func_id, u16 offset) +{ + struct bpf_kfunc_desc desc = { + .func_id = func_id, + .offset = offset, + }; + struct bpf_kfunc_desc_tab *tab; + + tab = prog->aux->kfunc_tab; + return bsearch(&desc, tab->descs, tab->nr_descs, + sizeof(tab->descs[0]), kfunc_desc_cmp_by_id_off); +} + +int bpf_get_kfunc_addr(const struct bpf_prog *prog, u32 func_id, + u16 btf_fd_idx, u8 **func_addr) +{ + const struct bpf_kfunc_desc *desc; + + desc = find_kfunc_desc(prog, func_id, btf_fd_idx); + if (!desc) + return -EFAULT; + + *func_addr = (u8 *)desc->addr; + return 0; +} + +static struct btf *__find_kfunc_desc_btf(struct bpf_verifier_env *env, + s16 offset) +{ + struct bpf_kfunc_btf kf_btf = { .offset = offset }; + struct bpf_kfunc_btf_tab *tab; + struct bpf_kfunc_btf *b; + struct module *mod; + struct btf *btf; + int btf_fd; + + tab = env->prog->aux->kfunc_btf_tab; + b = bsearch(&kf_btf, tab->descs, tab->nr_descs, + sizeof(tab->descs[0]), kfunc_btf_cmp_by_off); + if (!b) { + if (tab->nr_descs == MAX_KFUNC_BTFS) { + verbose(env, "too many different module BTFs\n"); + return ERR_PTR(-E2BIG); + } + + if (bpfptr_is_null(env->fd_array)) { + verbose(env, "kfunc offset > 0 without fd_array is invalid\n"); + return ERR_PTR(-EPROTO); + } + + if (copy_from_bpfptr_offset(&btf_fd, env->fd_array, + offset * sizeof(btf_fd), + sizeof(btf_fd))) + return ERR_PTR(-EFAULT); + + btf = btf_get_by_fd(btf_fd); + if (IS_ERR(btf)) { + verbose(env, "invalid module BTF fd specified\n"); + return btf; + } + + if (!btf_is_module(btf)) { + verbose(env, "BTF fd for kfunc is not a module BTF\n"); + btf_put(btf); + return ERR_PTR(-EINVAL); + } + + mod = btf_try_get_module(btf); + if (!mod) { + btf_put(btf); + return ERR_PTR(-ENXIO); + } + + b = &tab->descs[tab->nr_descs++]; + b->btf = btf; + b->module = mod; + b->offset = offset; + + sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]), + kfunc_btf_cmp_by_off, NULL); + } + return b->btf; +} + +void bpf_free_kfunc_btf_tab(struct bpf_kfunc_btf_tab *tab) +{ + if (!tab) + return; + + while (tab->nr_descs--) { + module_put(tab->descs[tab->nr_descs].module); + btf_put(tab->descs[tab->nr_descs].btf); + } + kfree(tab); +} + +static struct btf *find_kfunc_desc_btf(struct bpf_verifier_env *env, s16 offset) +{ + if (offset) { + if (offset < 0) { + /* In the future, this can be allowed to increase limit + * of fd index into fd_array, interpreted as u16. + */ + verbose(env, "negative offset disallowed for kernel module function call\n"); + return ERR_PTR(-EINVAL); + } + + return __find_kfunc_desc_btf(env, offset); + } + return btf_vmlinux ?: ERR_PTR(-ENOENT); +} + +static int add_kfunc_call(struct bpf_verifier_env *env, u32 func_id, s16 offset) +{ + const struct btf_type *func, *func_proto; + struct bpf_kfunc_btf_tab *btf_tab; + struct bpf_kfunc_desc_tab *tab; + struct bpf_prog_aux *prog_aux; + struct bpf_kfunc_desc *desc; + const char *func_name; + struct btf *desc_btf; + unsigned long call_imm; + unsigned long addr; + int err; + + prog_aux = env->prog->aux; + tab = prog_aux->kfunc_tab; + btf_tab = prog_aux->kfunc_btf_tab; + if (!tab) { + if (!btf_vmlinux) { + verbose(env, "calling kernel function is not supported without CONFIG_DEBUG_INFO_BTF\n"); + return -ENOTSUPP; + } + + if (!env->prog->jit_requested) { + verbose(env, "JIT is required for calling kernel function\n"); + return -ENOTSUPP; + } + + if (!bpf_jit_supports_kfunc_call()) { + verbose(env, "JIT does not support calling kernel function\n"); + return -ENOTSUPP; + } + + if (!env->prog->gpl_compatible) { + verbose(env, "cannot call kernel function from non-GPL compatible program\n"); + return -EINVAL; + } + + tab = kzalloc(sizeof(*tab), GFP_KERNEL); + if (!tab) + return -ENOMEM; + prog_aux->kfunc_tab = tab; + } + + /* func_id == 0 is always invalid, but instead of returning an error, be + * conservative and wait until the code elimination pass before returning + * error, so that invalid calls that get pruned out can be in BPF programs + * loaded from userspace. It is also required that offset be untouched + * for such calls. + */ + if (!func_id && !offset) + return 0; + + if (!btf_tab && offset) { + btf_tab = kzalloc(sizeof(*btf_tab), GFP_KERNEL); + if (!btf_tab) + return -ENOMEM; + prog_aux->kfunc_btf_tab = btf_tab; + } + + desc_btf = find_kfunc_desc_btf(env, offset); + if (IS_ERR(desc_btf)) { + verbose(env, "failed to find BTF for kernel function\n"); + return PTR_ERR(desc_btf); + } + + if (find_kfunc_desc(env->prog, func_id, offset)) + return 0; + + if (tab->nr_descs == MAX_KFUNC_DESCS) { + verbose(env, "too many different kernel function calls\n"); + return -E2BIG; + } + + func = btf_type_by_id(desc_btf, func_id); + if (!func || !btf_type_is_func(func)) { + verbose(env, "kernel btf_id %u is not a function\n", + func_id); + return -EINVAL; + } + func_proto = btf_type_by_id(desc_btf, func->type); + if (!func_proto || !btf_type_is_func_proto(func_proto)) { + verbose(env, "kernel function btf_id %u does not have a valid func_proto\n", + func_id); + return -EINVAL; + } + + func_name = btf_name_by_offset(desc_btf, func->name_off); + addr = kallsyms_lookup_name(func_name); + if (!addr) { + verbose(env, "cannot find address for kernel function %s\n", + func_name); + return -EINVAL; + } + specialize_kfunc(env, func_id, offset, &addr); + + if (bpf_jit_supports_far_kfunc_call()) { + call_imm = func_id; + } else { + call_imm = BPF_CALL_IMM(addr); + /* Check whether the relative offset overflows desc->imm */ + if ((unsigned long)(s32)call_imm != call_imm) { + verbose(env, "address of kernel function %s is out of range\n", + func_name); + return -EINVAL; + } + } + + if (bpf_dev_bound_kfunc_id(func_id)) { + err = bpf_dev_bound_kfunc_check(&env->log, prog_aux); + if (err) + return err; + } + + desc = &tab->descs[tab->nr_descs++]; + desc->func_id = func_id; + desc->imm = call_imm; + desc->offset = offset; + desc->addr = addr; + err = btf_distill_func_proto(&env->log, desc_btf, + func_proto, func_name, + &desc->func_model); + if (!err) + sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]), + kfunc_desc_cmp_by_id_off, NULL); + return err; +} + +static int kfunc_desc_cmp_by_imm_off(const void *a, const void *b) +{ + const struct bpf_kfunc_desc *d0 = a; + const struct bpf_kfunc_desc *d1 = b; + + if (d0->imm != d1->imm) + return d0->imm < d1->imm ? -1 : 1; + if (d0->offset != d1->offset) + return d0->offset < d1->offset ? -1 : 1; + return 0; +} + +static void sort_kfunc_descs_by_imm_off(struct bpf_prog *prog) +{ + struct bpf_kfunc_desc_tab *tab; + + tab = prog->aux->kfunc_tab; + if (!tab) + return; + + sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]), + kfunc_desc_cmp_by_imm_off, NULL); +} + +bool bpf_prog_has_kfunc_call(const struct bpf_prog *prog) +{ + return !!prog->aux->kfunc_tab; +} + +const struct btf_func_model * +bpf_jit_find_kfunc_model(const struct bpf_prog *prog, + const struct bpf_insn *insn) +{ + const struct bpf_kfunc_desc desc = { + .imm = insn->imm, + .offset = insn->off, + }; + const struct bpf_kfunc_desc *res; + struct bpf_kfunc_desc_tab *tab; + + tab = prog->aux->kfunc_tab; + res = bsearch(&desc, tab->descs, tab->nr_descs, + sizeof(tab->descs[0]), kfunc_desc_cmp_by_imm_off); + + return res ? &res->func_model : NULL; +} + +static int add_subprog_and_kfunc(struct bpf_verifier_env *env) +{ + struct bpf_subprog_info *subprog = env->subprog_info; + struct bpf_insn *insn = env->prog->insnsi; + int i, ret, insn_cnt = env->prog->len; + + /* Add entry function. */ + ret = add_subprog(env, 0); + if (ret) + return ret; + + for (i = 0; i < insn_cnt; i++, insn++) { + if (!bpf_pseudo_func(insn) && !bpf_pseudo_call(insn) && + !bpf_pseudo_kfunc_call(insn)) + continue; + + if (!env->bpf_capable) { + verbose(env, "loading/calling other bpf or kernel functions are allowed for CAP_BPF and CAP_SYS_ADMIN\n"); + return -EPERM; + } + + if (bpf_pseudo_func(insn) || bpf_pseudo_call(insn)) + ret = add_subprog(env, i + insn->imm + 1); + else + ret = add_kfunc_call(env, insn->imm, insn->off); + + if (ret < 0) + return ret; + } + + /* Add a fake 'exit' subprog which could simplify subprog iteration + * logic. 'subprog_cnt' should not be increased. + */ + subprog[env->subprog_cnt].start = insn_cnt; + + if (env->log.level & BPF_LOG_LEVEL2) + for (i = 0; i < env->subprog_cnt; i++) + verbose(env, "func#%d @%d\n", i, subprog[i].start); + + return 0; +} + +static int check_subprogs(struct bpf_verifier_env *env) +{ + int i, subprog_start, subprog_end, off, cur_subprog = 0; + struct bpf_subprog_info *subprog = env->subprog_info; + struct bpf_insn *insn = env->prog->insnsi; + int insn_cnt = env->prog->len; + + /* now check that all jumps are within the same subprog */ + subprog_start = subprog[cur_subprog].start; + subprog_end = subprog[cur_subprog + 1].start; + for (i = 0; i < insn_cnt; i++) { + u8 code = insn[i].code; + + if (code == (BPF_JMP | BPF_CALL) && + insn[i].src_reg == 0 && + insn[i].imm == BPF_FUNC_tail_call) + subprog[cur_subprog].has_tail_call = true; + if (BPF_CLASS(code) == BPF_LD && + (BPF_MODE(code) == BPF_ABS || BPF_MODE(code) == BPF_IND)) + subprog[cur_subprog].has_ld_abs = true; + if (BPF_CLASS(code) != BPF_JMP && BPF_CLASS(code) != BPF_JMP32) + goto next; + if (BPF_OP(code) == BPF_EXIT || BPF_OP(code) == BPF_CALL) + goto next; + if (code == (BPF_JMP32 | BPF_JA)) + off = i + insn[i].imm + 1; + else + off = i + insn[i].off + 1; + if (off < subprog_start || off >= subprog_end) { + verbose(env, "jump out of range from insn %d to %d\n", i, off); + return -EINVAL; + } +next: + if (i == subprog_end - 1) { + /* to avoid fall-through from one subprog into another + * the last insn of the subprog should be either exit + * or unconditional jump back + */ + if (code != (BPF_JMP | BPF_EXIT) && + code != (BPF_JMP32 | BPF_JA) && + code != (BPF_JMP | BPF_JA)) { + verbose(env, "last insn is not an exit or jmp\n"); + return -EINVAL; + } + subprog_start = subprog_end; + cur_subprog++; + if (cur_subprog < env->subprog_cnt) + subprog_end = subprog[cur_subprog + 1].start; + } + } + return 0; +} + +/* Parentage chain of this register (or stack slot) should take care of all + * issues like callee-saved registers, stack slot allocation time, etc. + */ +static int mark_reg_read(struct bpf_verifier_env *env, + const struct bpf_reg_state *state, + struct bpf_reg_state *parent, u8 flag) +{ + bool writes = parent == state->parent; /* Observe write marks */ + int cnt = 0; + + while (parent) { + /* if read wasn't screened by an earlier write ... */ + if (writes && state->live & REG_LIVE_WRITTEN) + break; + if (parent->live & REG_LIVE_DONE) { + verbose(env, "verifier BUG type %s var_off %lld off %d\n", + reg_type_str(env, parent->type), + parent->var_off.value, parent->off); + return -EFAULT; + } + /* The first condition is more likely to be true than the + * second, checked it first. + */ + if ((parent->live & REG_LIVE_READ) == flag || + parent->live & REG_LIVE_READ64) + /* The parentage chain never changes and + * this parent was already marked as LIVE_READ. + * There is no need to keep walking the chain again and + * keep re-marking all parents as LIVE_READ. + * This case happens when the same register is read + * multiple times without writes into it in-between. + * Also, if parent has the stronger REG_LIVE_READ64 set, + * then no need to set the weak REG_LIVE_READ32. + */ + break; + /* ... then we depend on parent's value */ + parent->live |= flag; + /* REG_LIVE_READ64 overrides REG_LIVE_READ32. */ + if (flag == REG_LIVE_READ64) + parent->live &= ~REG_LIVE_READ32; + state = parent; + parent = state->parent; + writes = true; + cnt++; + } + + if (env->longest_mark_read_walk < cnt) + env->longest_mark_read_walk = cnt; + return 0; +} + +static int mark_dynptr_read(struct bpf_verifier_env *env, struct bpf_reg_state *reg) +{ + struct bpf_func_state *state = func(env, reg); + int spi, ret; + + /* For CONST_PTR_TO_DYNPTR, it must have already been done by + * check_reg_arg in check_helper_call and mark_btf_func_reg_size in + * check_kfunc_call. + */ + if (reg->type == CONST_PTR_TO_DYNPTR) + return 0; + spi = dynptr_get_spi(env, reg); + if (spi < 0) + return spi; + /* Caller ensures dynptr is valid and initialized, which means spi is in + * bounds and spi is the first dynptr slot. Simply mark stack slot as + * read. + */ + ret = mark_reg_read(env, &state->stack[spi].spilled_ptr, + state->stack[spi].spilled_ptr.parent, REG_LIVE_READ64); + if (ret) + return ret; + return mark_reg_read(env, &state->stack[spi - 1].spilled_ptr, + state->stack[spi - 1].spilled_ptr.parent, REG_LIVE_READ64); +} + +static int mark_iter_read(struct bpf_verifier_env *env, struct bpf_reg_state *reg, + int spi, int nr_slots) +{ + struct bpf_func_state *state = func(env, reg); + int err, i; + + for (i = 0; i < nr_slots; i++) { + struct bpf_reg_state *st = &state->stack[spi - i].spilled_ptr; + + err = mark_reg_read(env, st, st->parent, REG_LIVE_READ64); + if (err) + return err; + + mark_stack_slot_scratched(env, spi - i); + } + + return 0; +} + +/* This function is supposed to be used by the following 32-bit optimization + * code only. It returns TRUE if the source or destination register operates + * on 64-bit, otherwise return FALSE. + */ +static bool is_reg64(struct bpf_verifier_env *env, struct bpf_insn *insn, + u32 regno, struct bpf_reg_state *reg, enum reg_arg_type t) +{ + u8 code, class, op; + + code = insn->code; + class = BPF_CLASS(code); + op = BPF_OP(code); + if (class == BPF_JMP) { + /* BPF_EXIT for "main" will reach here. Return TRUE + * conservatively. + */ + if (op == BPF_EXIT) + return true; + if (op == BPF_CALL) { + /* BPF to BPF call will reach here because of marking + * caller saved clobber with DST_OP_NO_MARK for which we + * don't care the register def because they are anyway + * marked as NOT_INIT already. + */ + if (insn->src_reg == BPF_PSEUDO_CALL) + return false; + /* Helper call will reach here because of arg type + * check, conservatively return TRUE. + */ + if (t == SRC_OP) + return true; + + return false; + } + } + + if (class == BPF_ALU64 && op == BPF_END && (insn->imm == 16 || insn->imm == 32)) + return false; + + if (class == BPF_ALU64 || class == BPF_JMP || + (class == BPF_ALU && op == BPF_END && insn->imm == 64)) + return true; + + if (class == BPF_ALU || class == BPF_JMP32) + return false; + + if (class == BPF_LDX) { + if (t != SRC_OP) + return BPF_SIZE(code) == BPF_DW; + /* LDX source must be ptr. */ + return true; + } + + if (class == BPF_STX) { + /* BPF_STX (including atomic variants) has multiple source + * operands, one of which is a ptr. Check whether the caller is + * asking about it. + */ + if (t == SRC_OP && reg->type != SCALAR_VALUE) + return true; + return BPF_SIZE(code) == BPF_DW; + } + + if (class == BPF_LD) { + u8 mode = BPF_MODE(code); + + /* LD_IMM64 */ + if (mode == BPF_IMM) + return true; + + /* Both LD_IND and LD_ABS return 32-bit data. */ + if (t != SRC_OP) + return false; + + /* Implicit ctx ptr. */ + if (regno == BPF_REG_6) + return true; + + /* Explicit source could be any width. */ + return true; + } + + if (class == BPF_ST) + /* The only source register for BPF_ST is a ptr. */ + return true; + + /* Conservatively return true at default. */ + return true; +} + +/* Return the regno defined by the insn, or -1. */ +static int insn_def_regno(const struct bpf_insn *insn) +{ + switch (BPF_CLASS(insn->code)) { + case BPF_JMP: + case BPF_JMP32: + case BPF_ST: + return -1; + case BPF_STX: + if (BPF_MODE(insn->code) == BPF_ATOMIC && + (insn->imm & BPF_FETCH)) { + if (insn->imm == BPF_CMPXCHG) + return BPF_REG_0; + else + return insn->src_reg; + } else { + return -1; + } + default: + return insn->dst_reg; + } +} + +/* Return TRUE if INSN has defined any 32-bit value explicitly. */ +static bool insn_has_def32(struct bpf_verifier_env *env, struct bpf_insn *insn) +{ + int dst_reg = insn_def_regno(insn); + + if (dst_reg == -1) + return false; + + return !is_reg64(env, insn, dst_reg, NULL, DST_OP); +} + +static void mark_insn_zext(struct bpf_verifier_env *env, + struct bpf_reg_state *reg) +{ + s32 def_idx = reg->subreg_def; + + if (def_idx == DEF_NOT_SUBREG) + return; + + env->insn_aux_data[def_idx - 1].zext_dst = true; + /* The dst will be zero extended, so won't be sub-register anymore. */ + reg->subreg_def = DEF_NOT_SUBREG; +} + +static int __check_reg_arg(struct bpf_verifier_env *env, struct bpf_reg_state *regs, u32 regno, + enum reg_arg_type t) +{ + struct bpf_insn *insn = env->prog->insnsi + env->insn_idx; + struct bpf_reg_state *reg; + bool rw64; + + if (regno >= MAX_BPF_REG) { + verbose(env, "R%d is invalid\n", regno); + return -EINVAL; + } + + mark_reg_scratched(env, regno); + + reg = ®s[regno]; + rw64 = is_reg64(env, insn, regno, reg, t); + if (t == SRC_OP) { + /* check whether register used as source operand can be read */ + if (reg->type == NOT_INIT) { + verbose(env, "R%d !read_ok\n", regno); + return -EACCES; + } + /* We don't need to worry about FP liveness because it's read-only */ + if (regno == BPF_REG_FP) + return 0; + + if (rw64) + mark_insn_zext(env, reg); + + return mark_reg_read(env, reg, reg->parent, + rw64 ? REG_LIVE_READ64 : REG_LIVE_READ32); + } else { + /* check whether register used as dest operand can be written to */ + if (regno == BPF_REG_FP) { + verbose(env, "frame pointer is read only\n"); + return -EACCES; + } + reg->live |= REG_LIVE_WRITTEN; + reg->subreg_def = rw64 ? DEF_NOT_SUBREG : env->insn_idx + 1; + if (t == DST_OP) + mark_reg_unknown(env, regs, regno); + } + return 0; +} + +static int check_reg_arg(struct bpf_verifier_env *env, u32 regno, + enum reg_arg_type t) +{ + struct bpf_verifier_state *vstate = env->cur_state; + struct bpf_func_state *state = vstate->frame[vstate->curframe]; + + return __check_reg_arg(env, state->regs, regno, t); +} + +static void mark_jmp_point(struct bpf_verifier_env *env, int idx) +{ + env->insn_aux_data[idx].jmp_point = true; +} + +static bool is_jmp_point(struct bpf_verifier_env *env, int insn_idx) +{ + return env->insn_aux_data[insn_idx].jmp_point; +} + +/* for any branch, call, exit record the history of jmps in the given state */ +static int push_jmp_history(struct bpf_verifier_env *env, + struct bpf_verifier_state *cur) +{ + u32 cnt = cur->jmp_history_cnt; + struct bpf_idx_pair *p; + size_t alloc_size; + + if (!is_jmp_point(env, env->insn_idx)) + return 0; + + cnt++; + alloc_size = kmalloc_size_roundup(size_mul(cnt, sizeof(*p))); + p = krealloc(cur->jmp_history, alloc_size, GFP_USER); + if (!p) + return -ENOMEM; + p[cnt - 1].idx = env->insn_idx; + p[cnt - 1].prev_idx = env->prev_insn_idx; + cur->jmp_history = p; + cur->jmp_history_cnt = cnt; + return 0; +} + +/* Backtrack one insn at a time. If idx is not at the top of recorded + * history then previous instruction came from straight line execution. + * Return -ENOENT if we exhausted all instructions within given state. + * + * It's legal to have a bit of a looping with the same starting and ending + * insn index within the same state, e.g.: 3->4->5->3, so just because current + * instruction index is the same as state's first_idx doesn't mean we are + * done. If there is still some jump history left, we should keep going. We + * need to take into account that we might have a jump history between given + * state's parent and itself, due to checkpointing. In this case, we'll have + * history entry recording a jump from last instruction of parent state and + * first instruction of given state. + */ +static int get_prev_insn_idx(struct bpf_verifier_state *st, int i, + u32 *history) +{ + u32 cnt = *history; + + if (i == st->first_insn_idx) { + if (cnt == 0) + return -ENOENT; + if (cnt == 1 && st->jmp_history[0].idx == i) + return -ENOENT; + } + + if (cnt && st->jmp_history[cnt - 1].idx == i) { + i = st->jmp_history[cnt - 1].prev_idx; + (*history)--; + } else { + i--; + } + return i; +} + +static const char *disasm_kfunc_name(void *data, const struct bpf_insn *insn) +{ + const struct btf_type *func; + struct btf *desc_btf; + + if (insn->src_reg != BPF_PSEUDO_KFUNC_CALL) + return NULL; + + desc_btf = find_kfunc_desc_btf(data, insn->off); + if (IS_ERR(desc_btf)) + return "<error>"; + + func = btf_type_by_id(desc_btf, insn->imm); + return btf_name_by_offset(desc_btf, func->name_off); +} + +static inline void bt_init(struct backtrack_state *bt, u32 frame) +{ + bt->frame = frame; +} + +static inline void bt_reset(struct backtrack_state *bt) +{ + struct bpf_verifier_env *env = bt->env; + + memset(bt, 0, sizeof(*bt)); + bt->env = env; +} + +static inline u32 bt_empty(struct backtrack_state *bt) +{ + u64 mask = 0; + int i; + + for (i = 0; i <= bt->frame; i++) + mask |= bt->reg_masks[i] | bt->stack_masks[i]; + + return mask == 0; +} + +static inline int bt_subprog_enter(struct backtrack_state *bt) +{ + if (bt->frame == MAX_CALL_FRAMES - 1) { + verbose(bt->env, "BUG subprog enter from frame %d\n", bt->frame); + WARN_ONCE(1, "verifier backtracking bug"); + return -EFAULT; + } + bt->frame++; + return 0; +} + +static inline int bt_subprog_exit(struct backtrack_state *bt) +{ + if (bt->frame == 0) { + verbose(bt->env, "BUG subprog exit from frame 0\n"); + WARN_ONCE(1, "verifier backtracking bug"); + return -EFAULT; + } + bt->frame--; + return 0; +} + +static inline void bt_set_frame_reg(struct backtrack_state *bt, u32 frame, u32 reg) +{ + bt->reg_masks[frame] |= 1 << reg; +} + +static inline void bt_clear_frame_reg(struct backtrack_state *bt, u32 frame, u32 reg) +{ + bt->reg_masks[frame] &= ~(1 << reg); +} + +static inline void bt_set_reg(struct backtrack_state *bt, u32 reg) +{ + bt_set_frame_reg(bt, bt->frame, reg); +} + +static inline void bt_clear_reg(struct backtrack_state *bt, u32 reg) +{ + bt_clear_frame_reg(bt, bt->frame, reg); +} + +static inline void bt_set_frame_slot(struct backtrack_state *bt, u32 frame, u32 slot) +{ + bt->stack_masks[frame] |= 1ull << slot; +} + +static inline void bt_clear_frame_slot(struct backtrack_state *bt, u32 frame, u32 slot) +{ + bt->stack_masks[frame] &= ~(1ull << slot); +} + +static inline void bt_set_slot(struct backtrack_state *bt, u32 slot) +{ + bt_set_frame_slot(bt, bt->frame, slot); +} + +static inline void bt_clear_slot(struct backtrack_state *bt, u32 slot) +{ + bt_clear_frame_slot(bt, bt->frame, slot); +} + +static inline u32 bt_frame_reg_mask(struct backtrack_state *bt, u32 frame) +{ + return bt->reg_masks[frame]; +} + +static inline u32 bt_reg_mask(struct backtrack_state *bt) +{ + return bt->reg_masks[bt->frame]; +} + +static inline u64 bt_frame_stack_mask(struct backtrack_state *bt, u32 frame) +{ + return bt->stack_masks[frame]; +} + +static inline u64 bt_stack_mask(struct backtrack_state *bt) +{ + return bt->stack_masks[bt->frame]; +} + +static inline bool bt_is_reg_set(struct backtrack_state *bt, u32 reg) +{ + return bt->reg_masks[bt->frame] & (1 << reg); +} + +static inline bool bt_is_slot_set(struct backtrack_state *bt, u32 slot) +{ + return bt->stack_masks[bt->frame] & (1ull << slot); +} + +/* format registers bitmask, e.g., "r0,r2,r4" for 0x15 mask */ +static void fmt_reg_mask(char *buf, ssize_t buf_sz, u32 reg_mask) +{ + DECLARE_BITMAP(mask, 64); + bool first = true; + int i, n; + + buf[0] = '\0'; + + bitmap_from_u64(mask, reg_mask); + for_each_set_bit(i, mask, 32) { + n = snprintf(buf, buf_sz, "%sr%d", first ? "" : ",", i); + first = false; + buf += n; + buf_sz -= n; + if (buf_sz < 0) + break; + } +} +/* format stack slots bitmask, e.g., "-8,-24,-40" for 0x15 mask */ +static void fmt_stack_mask(char *buf, ssize_t buf_sz, u64 stack_mask) +{ + DECLARE_BITMAP(mask, 64); + bool first = true; + int i, n; + + buf[0] = '\0'; + + bitmap_from_u64(mask, stack_mask); + for_each_set_bit(i, mask, 64) { + n = snprintf(buf, buf_sz, "%s%d", first ? "" : ",", -(i + 1) * 8); + first = false; + buf += n; + buf_sz -= n; + if (buf_sz < 0) + break; + } +} + +static bool calls_callback(struct bpf_verifier_env *env, int insn_idx); + +/* For given verifier state backtrack_insn() is called from the last insn to + * the first insn. Its purpose is to compute a bitmask of registers and + * stack slots that needs precision in the parent verifier state. + * + * @idx is an index of the instruction we are currently processing; + * @subseq_idx is an index of the subsequent instruction that: + * - *would be* executed next, if jump history is viewed in forward order; + * - *was* processed previously during backtracking. + */ +static int backtrack_insn(struct bpf_verifier_env *env, int idx, int subseq_idx, + struct backtrack_state *bt) +{ + const struct bpf_insn_cbs cbs = { + .cb_call = disasm_kfunc_name, + .cb_print = verbose, + .private_data = env, + }; + struct bpf_insn *insn = env->prog->insnsi + idx; + u8 class = BPF_CLASS(insn->code); + u8 opcode = BPF_OP(insn->code); + u8 mode = BPF_MODE(insn->code); + u32 dreg = insn->dst_reg; + u32 sreg = insn->src_reg; + u32 spi, i; + + if (insn->code == 0) + return 0; + if (env->log.level & BPF_LOG_LEVEL2) { + fmt_reg_mask(env->tmp_str_buf, TMP_STR_BUF_LEN, bt_reg_mask(bt)); + verbose(env, "mark_precise: frame%d: regs=%s ", + bt->frame, env->tmp_str_buf); + fmt_stack_mask(env->tmp_str_buf, TMP_STR_BUF_LEN, bt_stack_mask(bt)); + verbose(env, "stack=%s before ", env->tmp_str_buf); + verbose(env, "%d: ", idx); + print_bpf_insn(&cbs, insn, env->allow_ptr_leaks); + } + + if (class == BPF_ALU || class == BPF_ALU64) { + if (!bt_is_reg_set(bt, dreg)) + return 0; + if (opcode == BPF_END || opcode == BPF_NEG) { + /* sreg is reserved and unused + * dreg still need precision before this insn + */ + return 0; + } else if (opcode == BPF_MOV) { + if (BPF_SRC(insn->code) == BPF_X) { + /* dreg = sreg or dreg = (s8, s16, s32)sreg + * dreg needs precision after this insn + * sreg needs precision before this insn + */ + bt_clear_reg(bt, dreg); + bt_set_reg(bt, sreg); + } else { + /* dreg = K + * dreg needs precision after this insn. + * Corresponding register is already marked + * as precise=true in this verifier state. + * No further markings in parent are necessary + */ + bt_clear_reg(bt, dreg); + } + } else { + if (BPF_SRC(insn->code) == BPF_X) { + /* dreg += sreg + * both dreg and sreg need precision + * before this insn + */ + bt_set_reg(bt, sreg); + } /* else dreg += K + * dreg still needs precision before this insn + */ + } + } else if (class == BPF_LDX) { + if (!bt_is_reg_set(bt, dreg)) + return 0; + bt_clear_reg(bt, dreg); + + /* scalars can only be spilled into stack w/o losing precision. + * Load from any other memory can be zero extended. + * The desire to keep that precision is already indicated + * by 'precise' mark in corresponding register of this state. + * No further tracking necessary. + */ + if (insn->src_reg != BPF_REG_FP) + return 0; + + /* dreg = *(u64 *)[fp - off] was a fill from the stack. + * that [fp - off] slot contains scalar that needs to be + * tracked with precision + */ + spi = (-insn->off - 1) / BPF_REG_SIZE; + if (spi >= 64) { + verbose(env, "BUG spi %d\n", spi); + WARN_ONCE(1, "verifier backtracking bug"); + return -EFAULT; + } + bt_set_slot(bt, spi); + } else if (class == BPF_STX || class == BPF_ST) { + if (bt_is_reg_set(bt, dreg)) + /* stx & st shouldn't be using _scalar_ dst_reg + * to access memory. It means backtracking + * encountered a case of pointer subtraction. + */ + return -ENOTSUPP; + /* scalars can only be spilled into stack */ + if (insn->dst_reg != BPF_REG_FP) + return 0; + spi = (-insn->off - 1) / BPF_REG_SIZE; + if (spi >= 64) { + verbose(env, "BUG spi %d\n", spi); + WARN_ONCE(1, "verifier backtracking bug"); + return -EFAULT; + } + if (!bt_is_slot_set(bt, spi)) + return 0; + bt_clear_slot(bt, spi); + if (class == BPF_STX) + bt_set_reg(bt, sreg); + } else if (class == BPF_JMP || class == BPF_JMP32) { + if (bpf_pseudo_call(insn)) { + int subprog_insn_idx, subprog; + + subprog_insn_idx = idx + insn->imm + 1; + subprog = find_subprog(env, subprog_insn_idx); + if (subprog < 0) + return -EFAULT; + + if (subprog_is_global(env, subprog)) { + /* check that jump history doesn't have any + * extra instructions from subprog; the next + * instruction after call to global subprog + * should be literally next instruction in + * caller program + */ + WARN_ONCE(idx + 1 != subseq_idx, "verifier backtracking bug"); + /* r1-r5 are invalidated after subprog call, + * so for global func call it shouldn't be set + * anymore + */ + if (bt_reg_mask(bt) & BPF_REGMASK_ARGS) { + verbose(env, "BUG regs %x\n", bt_reg_mask(bt)); + WARN_ONCE(1, "verifier backtracking bug"); + return -EFAULT; + } + /* global subprog always sets R0 */ + bt_clear_reg(bt, BPF_REG_0); + return 0; + } else { + /* static subprog call instruction, which + * means that we are exiting current subprog, + * so only r1-r5 could be still requested as + * precise, r0 and r6-r10 or any stack slot in + * the current frame should be zero by now + */ + if (bt_reg_mask(bt) & ~BPF_REGMASK_ARGS) { + verbose(env, "BUG regs %x\n", bt_reg_mask(bt)); + WARN_ONCE(1, "verifier backtracking bug"); + return -EFAULT; + } + /* we don't track register spills perfectly, + * so fallback to force-precise instead of failing */ + if (bt_stack_mask(bt) != 0) + return -ENOTSUPP; + /* propagate r1-r5 to the caller */ + for (i = BPF_REG_1; i <= BPF_REG_5; i++) { + if (bt_is_reg_set(bt, i)) { + bt_clear_reg(bt, i); + bt_set_frame_reg(bt, bt->frame - 1, i); + } + } + if (bt_subprog_exit(bt)) + return -EFAULT; + return 0; + } + } else if (is_sync_callback_calling_insn(insn) && idx != subseq_idx - 1) { + /* exit from callback subprog to callback-calling helper or + * kfunc call. Use idx/subseq_idx check to discern it from + * straight line code backtracking. + * Unlike the subprog call handling above, we shouldn't + * propagate precision of r1-r5 (if any requested), as they are + * not actually arguments passed directly to callback subprogs + */ + if (bt_reg_mask(bt) & ~BPF_REGMASK_ARGS) { + verbose(env, "BUG regs %x\n", bt_reg_mask(bt)); + WARN_ONCE(1, "verifier backtracking bug"); + return -EFAULT; + } + if (bt_stack_mask(bt) != 0) + return -ENOTSUPP; + /* clear r1-r5 in callback subprog's mask */ + for (i = BPF_REG_1; i <= BPF_REG_5; i++) + bt_clear_reg(bt, i); + if (bt_subprog_exit(bt)) + return -EFAULT; + return 0; + } else if (opcode == BPF_CALL) { + /* kfunc with imm==0 is invalid and fixup_kfunc_call will + * catch this error later. Make backtracking conservative + * with ENOTSUPP. + */ + if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL && insn->imm == 0) + return -ENOTSUPP; + /* regular helper call sets R0 */ + bt_clear_reg(bt, BPF_REG_0); + if (bt_reg_mask(bt) & BPF_REGMASK_ARGS) { + /* if backtracing was looking for registers R1-R5 + * they should have been found already. + */ + verbose(env, "BUG regs %x\n", bt_reg_mask(bt)); + WARN_ONCE(1, "verifier backtracking bug"); + return -EFAULT; + } + } else if (opcode == BPF_EXIT) { + bool r0_precise; + + /* Backtracking to a nested function call, 'idx' is a part of + * the inner frame 'subseq_idx' is a part of the outer frame. + * In case of a regular function call, instructions giving + * precision to registers R1-R5 should have been found already. + * In case of a callback, it is ok to have R1-R5 marked for + * backtracking, as these registers are set by the function + * invoking callback. + */ + if (subseq_idx >= 0 && calls_callback(env, subseq_idx)) + for (i = BPF_REG_1; i <= BPF_REG_5; i++) + bt_clear_reg(bt, i); + if (bt_reg_mask(bt) & BPF_REGMASK_ARGS) { + verbose(env, "BUG regs %x\n", bt_reg_mask(bt)); + WARN_ONCE(1, "verifier backtracking bug"); + return -EFAULT; + } + + /* BPF_EXIT in subprog or callback always returns + * right after the call instruction, so by checking + * whether the instruction at subseq_idx-1 is subprog + * call or not we can distinguish actual exit from + * *subprog* from exit from *callback*. In the former + * case, we need to propagate r0 precision, if + * necessary. In the former we never do that. + */ + r0_precise = subseq_idx - 1 >= 0 && + bpf_pseudo_call(&env->prog->insnsi[subseq_idx - 1]) && + bt_is_reg_set(bt, BPF_REG_0); + + bt_clear_reg(bt, BPF_REG_0); + if (bt_subprog_enter(bt)) + return -EFAULT; + + if (r0_precise) + bt_set_reg(bt, BPF_REG_0); + /* r6-r9 and stack slots will stay set in caller frame + * bitmasks until we return back from callee(s) + */ + return 0; + } else if (BPF_SRC(insn->code) == BPF_X) { + if (!bt_is_reg_set(bt, dreg) && !bt_is_reg_set(bt, sreg)) + return 0; + /* dreg <cond> sreg + * Both dreg and sreg need precision before + * this insn. If only sreg was marked precise + * before it would be equally necessary to + * propagate it to dreg. + */ + bt_set_reg(bt, dreg); + bt_set_reg(bt, sreg); + /* else dreg <cond> K + * Only dreg still needs precision before + * this insn, so for the K-based conditional + * there is nothing new to be marked. + */ + } + } else if (class == BPF_LD) { + if (!bt_is_reg_set(bt, dreg)) + return 0; + bt_clear_reg(bt, dreg); + /* It's ld_imm64 or ld_abs or ld_ind. + * For ld_imm64 no further tracking of precision + * into parent is necessary + */ + if (mode == BPF_IND || mode == BPF_ABS) + /* to be analyzed */ + return -ENOTSUPP; + } + return 0; +} + +/* the scalar precision tracking algorithm: + * . at the start all registers have precise=false. + * . scalar ranges are tracked as normal through alu and jmp insns. + * . once precise value of the scalar register is used in: + * . ptr + scalar alu + * . if (scalar cond K|scalar) + * . helper_call(.., scalar, ...) where ARG_CONST is expected + * backtrack through the verifier states and mark all registers and + * stack slots with spilled constants that these scalar regisers + * should be precise. + * . during state pruning two registers (or spilled stack slots) + * are equivalent if both are not precise. + * + * Note the verifier cannot simply walk register parentage chain, + * since many different registers and stack slots could have been + * used to compute single precise scalar. + * + * The approach of starting with precise=true for all registers and then + * backtrack to mark a register as not precise when the verifier detects + * that program doesn't care about specific value (e.g., when helper + * takes register as ARG_ANYTHING parameter) is not safe. + * + * It's ok to walk single parentage chain of the verifier states. + * It's possible that this backtracking will go all the way till 1st insn. + * All other branches will be explored for needing precision later. + * + * The backtracking needs to deal with cases like: + * R8=map_value(id=0,off=0,ks=4,vs=1952,imm=0) R9_w=map_value(id=0,off=40,ks=4,vs=1952,imm=0) + * r9 -= r8 + * r5 = r9 + * if r5 > 0x79f goto pc+7 + * R5_w=inv(id=0,umax_value=1951,var_off=(0x0; 0x7ff)) + * r5 += 1 + * ... + * call bpf_perf_event_output#25 + * where .arg5_type = ARG_CONST_SIZE_OR_ZERO + * + * and this case: + * r6 = 1 + * call foo // uses callee's r6 inside to compute r0 + * r0 += r6 + * if r0 == 0 goto + * + * to track above reg_mask/stack_mask needs to be independent for each frame. + * + * Also if parent's curframe > frame where backtracking started, + * the verifier need to mark registers in both frames, otherwise callees + * may incorrectly prune callers. This is similar to + * commit 7640ead93924 ("bpf: verifier: make sure callees don't prune with caller differences") + * + * For now backtracking falls back into conservative marking. + */ +static void mark_all_scalars_precise(struct bpf_verifier_env *env, + struct bpf_verifier_state *st) +{ + struct bpf_func_state *func; + struct bpf_reg_state *reg; + int i, j; + + if (env->log.level & BPF_LOG_LEVEL2) { + verbose(env, "mark_precise: frame%d: falling back to forcing all scalars precise\n", + st->curframe); + } + + /* big hammer: mark all scalars precise in this path. + * pop_stack may still get !precise scalars. + * We also skip current state and go straight to first parent state, + * because precision markings in current non-checkpointed state are + * not needed. See why in the comment in __mark_chain_precision below. + */ + for (st = st->parent; st; st = st->parent) { + for (i = 0; i <= st->curframe; i++) { + func = st->frame[i]; + for (j = 0; j < BPF_REG_FP; j++) { + reg = &func->regs[j]; + if (reg->type != SCALAR_VALUE || reg->precise) + continue; + reg->precise = true; + if (env->log.level & BPF_LOG_LEVEL2) { + verbose(env, "force_precise: frame%d: forcing r%d to be precise\n", + i, j); + } + } + for (j = 0; j < func->allocated_stack / BPF_REG_SIZE; j++) { + if (!is_spilled_reg(&func->stack[j])) + continue; + reg = &func->stack[j].spilled_ptr; + if (reg->type != SCALAR_VALUE || reg->precise) + continue; + reg->precise = true; + if (env->log.level & BPF_LOG_LEVEL2) { + verbose(env, "force_precise: frame%d: forcing fp%d to be precise\n", + i, -(j + 1) * 8); + } + } + } + } +} + +static void mark_all_scalars_imprecise(struct bpf_verifier_env *env, struct bpf_verifier_state *st) +{ + struct bpf_func_state *func; + struct bpf_reg_state *reg; + int i, j; + + for (i = 0; i <= st->curframe; i++) { + func = st->frame[i]; + for (j = 0; j < BPF_REG_FP; j++) { + reg = &func->regs[j]; + if (reg->type != SCALAR_VALUE) + continue; + reg->precise = false; + } + for (j = 0; j < func->allocated_stack / BPF_REG_SIZE; j++) { + if (!is_spilled_reg(&func->stack[j])) + continue; + reg = &func->stack[j].spilled_ptr; + if (reg->type != SCALAR_VALUE) + continue; + reg->precise = false; + } + } +} + +static bool idset_contains(struct bpf_idset *s, u32 id) +{ + u32 i; + + for (i = 0; i < s->count; ++i) + if (s->ids[i] == id) + return true; + + return false; +} + +static int idset_push(struct bpf_idset *s, u32 id) +{ + if (WARN_ON_ONCE(s->count >= ARRAY_SIZE(s->ids))) + return -EFAULT; + s->ids[s->count++] = id; + return 0; +} + +static void idset_reset(struct bpf_idset *s) +{ + s->count = 0; +} + +/* Collect a set of IDs for all registers currently marked as precise in env->bt. + * Mark all registers with these IDs as precise. + */ +static int mark_precise_scalar_ids(struct bpf_verifier_env *env, struct bpf_verifier_state *st) +{ + struct bpf_idset *precise_ids = &env->idset_scratch; + struct backtrack_state *bt = &env->bt; + struct bpf_func_state *func; + struct bpf_reg_state *reg; + DECLARE_BITMAP(mask, 64); + int i, fr; + + idset_reset(precise_ids); + + for (fr = bt->frame; fr >= 0; fr--) { + func = st->frame[fr]; + + bitmap_from_u64(mask, bt_frame_reg_mask(bt, fr)); + for_each_set_bit(i, mask, 32) { + reg = &func->regs[i]; + if (!reg->id || reg->type != SCALAR_VALUE) + continue; + if (idset_push(precise_ids, reg->id)) + return -EFAULT; + } + + bitmap_from_u64(mask, bt_frame_stack_mask(bt, fr)); + for_each_set_bit(i, mask, 64) { + if (i >= func->allocated_stack / BPF_REG_SIZE) + break; + if (!is_spilled_scalar_reg(&func->stack[i])) + continue; + reg = &func->stack[i].spilled_ptr; + if (!reg->id) + continue; + if (idset_push(precise_ids, reg->id)) + return -EFAULT; + } + } + + for (fr = 0; fr <= st->curframe; ++fr) { + func = st->frame[fr]; + + for (i = BPF_REG_0; i < BPF_REG_10; ++i) { + reg = &func->regs[i]; + if (!reg->id) + continue; + if (!idset_contains(precise_ids, reg->id)) + continue; + bt_set_frame_reg(bt, fr, i); + } + for (i = 0; i < func->allocated_stack / BPF_REG_SIZE; ++i) { + if (!is_spilled_scalar_reg(&func->stack[i])) + continue; + reg = &func->stack[i].spilled_ptr; + if (!reg->id) + continue; + if (!idset_contains(precise_ids, reg->id)) + continue; + bt_set_frame_slot(bt, fr, i); + } + } + + return 0; +} + +/* + * __mark_chain_precision() backtracks BPF program instruction sequence and + * chain of verifier states making sure that register *regno* (if regno >= 0) + * and/or stack slot *spi* (if spi >= 0) are marked as precisely tracked + * SCALARS, as well as any other registers and slots that contribute to + * a tracked state of given registers/stack slots, depending on specific BPF + * assembly instructions (see backtrack_insns() for exact instruction handling + * logic). This backtracking relies on recorded jmp_history and is able to + * traverse entire chain of parent states. This process ends only when all the + * necessary registers/slots and their transitive dependencies are marked as + * precise. + * + * One important and subtle aspect is that precise marks *do not matter* in + * the currently verified state (current state). It is important to understand + * why this is the case. + * + * First, note that current state is the state that is not yet "checkpointed", + * i.e., it is not yet put into env->explored_states, and it has no children + * states as well. It's ephemeral, and can end up either a) being discarded if + * compatible explored state is found at some point or BPF_EXIT instruction is + * reached or b) checkpointed and put into env->explored_states, branching out + * into one or more children states. + * + * In the former case, precise markings in current state are completely + * ignored by state comparison code (see regsafe() for details). Only + * checkpointed ("old") state precise markings are important, and if old + * state's register/slot is precise, regsafe() assumes current state's + * register/slot as precise and checks value ranges exactly and precisely. If + * states turn out to be compatible, current state's necessary precise + * markings and any required parent states' precise markings are enforced + * after the fact with propagate_precision() logic, after the fact. But it's + * important to realize that in this case, even after marking current state + * registers/slots as precise, we immediately discard current state. So what + * actually matters is any of the precise markings propagated into current + * state's parent states, which are always checkpointed (due to b) case above). + * As such, for scenario a) it doesn't matter if current state has precise + * markings set or not. + * + * Now, for the scenario b), checkpointing and forking into child(ren) + * state(s). Note that before current state gets to checkpointing step, any + * processed instruction always assumes precise SCALAR register/slot + * knowledge: if precise value or range is useful to prune jump branch, BPF + * verifier takes this opportunity enthusiastically. Similarly, when + * register's value is used to calculate offset or memory address, exact + * knowledge of SCALAR range is assumed, checked, and enforced. So, similar to + * what we mentioned above about state comparison ignoring precise markings + * during state comparison, BPF verifier ignores and also assumes precise + * markings *at will* during instruction verification process. But as verifier + * assumes precision, it also propagates any precision dependencies across + * parent states, which are not yet finalized, so can be further restricted + * based on new knowledge gained from restrictions enforced by their children + * states. This is so that once those parent states are finalized, i.e., when + * they have no more active children state, state comparison logic in + * is_state_visited() would enforce strict and precise SCALAR ranges, if + * required for correctness. + * + * To build a bit more intuition, note also that once a state is checkpointed, + * the path we took to get to that state is not important. This is crucial + * property for state pruning. When state is checkpointed and finalized at + * some instruction index, it can be correctly and safely used to "short + * circuit" any *compatible* state that reaches exactly the same instruction + * index. I.e., if we jumped to that instruction from a completely different + * code path than original finalized state was derived from, it doesn't + * matter, current state can be discarded because from that instruction + * forward having a compatible state will ensure we will safely reach the + * exit. States describe preconditions for further exploration, but completely + * forget the history of how we got here. + * + * This also means that even if we needed precise SCALAR range to get to + * finalized state, but from that point forward *that same* SCALAR register is + * never used in a precise context (i.e., it's precise value is not needed for + * correctness), it's correct and safe to mark such register as "imprecise" + * (i.e., precise marking set to false). This is what we rely on when we do + * not set precise marking in current state. If no child state requires + * precision for any given SCALAR register, it's safe to dictate that it can + * be imprecise. If any child state does require this register to be precise, + * we'll mark it precise later retroactively during precise markings + * propagation from child state to parent states. + * + * Skipping precise marking setting in current state is a mild version of + * relying on the above observation. But we can utilize this property even + * more aggressively by proactively forgetting any precise marking in the + * current state (which we inherited from the parent state), right before we + * checkpoint it and branch off into new child state. This is done by + * mark_all_scalars_imprecise() to hopefully get more permissive and generic + * finalized states which help in short circuiting more future states. + */ +static int __mark_chain_precision(struct bpf_verifier_env *env, int regno) +{ + struct backtrack_state *bt = &env->bt; + struct bpf_verifier_state *st = env->cur_state; + int first_idx = st->first_insn_idx; + int last_idx = env->insn_idx; + int subseq_idx = -1; + struct bpf_func_state *func; + struct bpf_reg_state *reg; + bool skip_first = true; + int i, fr, err; + + if (!env->bpf_capable) + return 0; + + /* set frame number from which we are starting to backtrack */ + bt_init(bt, env->cur_state->curframe); + + /* Do sanity checks against current state of register and/or stack + * slot, but don't set precise flag in current state, as precision + * tracking in the current state is unnecessary. + */ + func = st->frame[bt->frame]; + if (regno >= 0) { + reg = &func->regs[regno]; + if (reg->type != SCALAR_VALUE) { + WARN_ONCE(1, "backtracing misuse"); + return -EFAULT; + } + bt_set_reg(bt, regno); + } + + if (bt_empty(bt)) + return 0; + + for (;;) { + DECLARE_BITMAP(mask, 64); + u32 history = st->jmp_history_cnt; + + if (env->log.level & BPF_LOG_LEVEL2) { + verbose(env, "mark_precise: frame%d: last_idx %d first_idx %d subseq_idx %d \n", + bt->frame, last_idx, first_idx, subseq_idx); + } + + /* If some register with scalar ID is marked as precise, + * make sure that all registers sharing this ID are also precise. + * This is needed to estimate effect of find_equal_scalars(). + * Do this at the last instruction of each state, + * bpf_reg_state::id fields are valid for these instructions. + * + * Allows to track precision in situation like below: + * + * r2 = unknown value + * ... + * --- state #0 --- + * ... + * r1 = r2 // r1 and r2 now share the same ID + * ... + * --- state #1 {r1.id = A, r2.id = A} --- + * ... + * if (r2 > 10) goto exit; // find_equal_scalars() assigns range to r1 + * ... + * --- state #2 {r1.id = A, r2.id = A} --- + * r3 = r10 + * r3 += r1 // need to mark both r1 and r2 + */ + if (mark_precise_scalar_ids(env, st)) + return -EFAULT; + + if (last_idx < 0) { + /* we are at the entry into subprog, which + * is expected for global funcs, but only if + * requested precise registers are R1-R5 + * (which are global func's input arguments) + */ + if (st->curframe == 0 && + st->frame[0]->subprogno > 0 && + st->frame[0]->callsite == BPF_MAIN_FUNC && + bt_stack_mask(bt) == 0 && + (bt_reg_mask(bt) & ~BPF_REGMASK_ARGS) == 0) { + bitmap_from_u64(mask, bt_reg_mask(bt)); + for_each_set_bit(i, mask, 32) { + reg = &st->frame[0]->regs[i]; + bt_clear_reg(bt, i); + if (reg->type == SCALAR_VALUE) + reg->precise = true; + } + return 0; + } + + verbose(env, "BUG backtracking func entry subprog %d reg_mask %x stack_mask %llx\n", + st->frame[0]->subprogno, bt_reg_mask(bt), bt_stack_mask(bt)); + WARN_ONCE(1, "verifier backtracking bug"); + return -EFAULT; + } + + for (i = last_idx;;) { + if (skip_first) { + err = 0; + skip_first = false; + } else { + err = backtrack_insn(env, i, subseq_idx, bt); + } + if (err == -ENOTSUPP) { + mark_all_scalars_precise(env, env->cur_state); + bt_reset(bt); + return 0; + } else if (err) { + return err; + } + if (bt_empty(bt)) + /* Found assignment(s) into tracked register in this state. + * Since this state is already marked, just return. + * Nothing to be tracked further in the parent state. + */ + return 0; + subseq_idx = i; + i = get_prev_insn_idx(st, i, &history); + if (i == -ENOENT) + break; + if (i >= env->prog->len) { + /* This can happen if backtracking reached insn 0 + * and there are still reg_mask or stack_mask + * to backtrack. + * It means the backtracking missed the spot where + * particular register was initialized with a constant. + */ + verbose(env, "BUG backtracking idx %d\n", i); + WARN_ONCE(1, "verifier backtracking bug"); + return -EFAULT; + } + } + st = st->parent; + if (!st) + break; + + for (fr = bt->frame; fr >= 0; fr--) { + func = st->frame[fr]; + bitmap_from_u64(mask, bt_frame_reg_mask(bt, fr)); + for_each_set_bit(i, mask, 32) { + reg = &func->regs[i]; + if (reg->type != SCALAR_VALUE) { + bt_clear_frame_reg(bt, fr, i); + continue; + } + if (reg->precise) + bt_clear_frame_reg(bt, fr, i); + else + reg->precise = true; + } + + bitmap_from_u64(mask, bt_frame_stack_mask(bt, fr)); + for_each_set_bit(i, mask, 64) { + if (i >= func->allocated_stack / BPF_REG_SIZE) { + /* the sequence of instructions: + * 2: (bf) r3 = r10 + * 3: (7b) *(u64 *)(r3 -8) = r0 + * 4: (79) r4 = *(u64 *)(r10 -8) + * doesn't contain jmps. It's backtracked + * as a single block. + * During backtracking insn 3 is not recognized as + * stack access, so at the end of backtracking + * stack slot fp-8 is still marked in stack_mask. + * However the parent state may not have accessed + * fp-8 and it's "unallocated" stack space. + * In such case fallback to conservative. + */ + mark_all_scalars_precise(env, env->cur_state); + bt_reset(bt); + return 0; + } + + if (!is_spilled_scalar_reg(&func->stack[i])) { + bt_clear_frame_slot(bt, fr, i); + continue; + } + reg = &func->stack[i].spilled_ptr; + if (reg->precise) + bt_clear_frame_slot(bt, fr, i); + else + reg->precise = true; + } + if (env->log.level & BPF_LOG_LEVEL2) { + fmt_reg_mask(env->tmp_str_buf, TMP_STR_BUF_LEN, + bt_frame_reg_mask(bt, fr)); + verbose(env, "mark_precise: frame%d: parent state regs=%s ", + fr, env->tmp_str_buf); + fmt_stack_mask(env->tmp_str_buf, TMP_STR_BUF_LEN, + bt_frame_stack_mask(bt, fr)); + verbose(env, "stack=%s: ", env->tmp_str_buf); + print_verifier_state(env, func, true); + } + } + + if (bt_empty(bt)) + return 0; + + subseq_idx = first_idx; + last_idx = st->last_insn_idx; + first_idx = st->first_insn_idx; + } + + /* if we still have requested precise regs or slots, we missed + * something (e.g., stack access through non-r10 register), so + * fallback to marking all precise + */ + if (!bt_empty(bt)) { + mark_all_scalars_precise(env, env->cur_state); + bt_reset(bt); + } + + return 0; +} + +int mark_chain_precision(struct bpf_verifier_env *env, int regno) +{ + return __mark_chain_precision(env, regno); +} + +/* mark_chain_precision_batch() assumes that env->bt is set in the caller to + * desired reg and stack masks across all relevant frames + */ +static int mark_chain_precision_batch(struct bpf_verifier_env *env) +{ + return __mark_chain_precision(env, -1); +} + +static bool is_spillable_regtype(enum bpf_reg_type type) +{ + switch (base_type(type)) { + case PTR_TO_MAP_VALUE: + case PTR_TO_STACK: + case PTR_TO_CTX: + case PTR_TO_PACKET: + case PTR_TO_PACKET_META: + case PTR_TO_PACKET_END: + case PTR_TO_FLOW_KEYS: + case CONST_PTR_TO_MAP: + case PTR_TO_SOCKET: + case PTR_TO_SOCK_COMMON: + case PTR_TO_TCP_SOCK: + case PTR_TO_XDP_SOCK: + case PTR_TO_BTF_ID: + case PTR_TO_BUF: + case PTR_TO_MEM: + case PTR_TO_FUNC: + case PTR_TO_MAP_KEY: + return true; + default: + return false; + } +} + +/* Does this register contain a constant zero? */ +static bool register_is_null(struct bpf_reg_state *reg) +{ + return reg->type == SCALAR_VALUE && tnum_equals_const(reg->var_off, 0); +} + +static bool register_is_const(struct bpf_reg_state *reg) +{ + return reg->type == SCALAR_VALUE && tnum_is_const(reg->var_off); +} + +static bool __is_scalar_unbounded(struct bpf_reg_state *reg) +{ + return tnum_is_unknown(reg->var_off) && + reg->smin_value == S64_MIN && reg->smax_value == S64_MAX && + reg->umin_value == 0 && reg->umax_value == U64_MAX && + reg->s32_min_value == S32_MIN && reg->s32_max_value == S32_MAX && + reg->u32_min_value == 0 && reg->u32_max_value == U32_MAX; +} + +static bool register_is_bounded(struct bpf_reg_state *reg) +{ + return reg->type == SCALAR_VALUE && !__is_scalar_unbounded(reg); +} + +static bool __is_pointer_value(bool allow_ptr_leaks, + const struct bpf_reg_state *reg) +{ + if (allow_ptr_leaks) + return false; + + return reg->type != SCALAR_VALUE; +} + +/* Copy src state preserving dst->parent and dst->live fields */ +static void copy_register_state(struct bpf_reg_state *dst, const struct bpf_reg_state *src) +{ + struct bpf_reg_state *parent = dst->parent; + enum bpf_reg_liveness live = dst->live; + + *dst = *src; + dst->parent = parent; + dst->live = live; +} + +static void save_register_state(struct bpf_func_state *state, + int spi, struct bpf_reg_state *reg, + int size) +{ + int i; + + copy_register_state(&state->stack[spi].spilled_ptr, reg); + if (size == BPF_REG_SIZE) + state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN; + + for (i = BPF_REG_SIZE; i > BPF_REG_SIZE - size; i--) + state->stack[spi].slot_type[i - 1] = STACK_SPILL; + + /* size < 8 bytes spill */ + for (; i; i--) + scrub_spilled_slot(&state->stack[spi].slot_type[i - 1]); +} + +static bool is_bpf_st_mem(struct bpf_insn *insn) +{ + return BPF_CLASS(insn->code) == BPF_ST && BPF_MODE(insn->code) == BPF_MEM; +} + +/* check_stack_{read,write}_fixed_off functions track spill/fill of registers, + * stack boundary and alignment are checked in check_mem_access() + */ +static int check_stack_write_fixed_off(struct bpf_verifier_env *env, + /* stack frame we're writing to */ + struct bpf_func_state *state, + int off, int size, int value_regno, + int insn_idx) +{ + struct bpf_func_state *cur; /* state of the current function */ + int i, slot = -off - 1, spi = slot / BPF_REG_SIZE, err; + struct bpf_insn *insn = &env->prog->insnsi[insn_idx]; + struct bpf_reg_state *reg = NULL; + u32 dst_reg = insn->dst_reg; + + /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0, + * so it's aligned access and [off, off + size) are within stack limits + */ + if (!env->allow_ptr_leaks && + is_spilled_reg(&state->stack[spi]) && + size != BPF_REG_SIZE) { + verbose(env, "attempt to corrupt spilled pointer on stack\n"); + return -EACCES; + } + + cur = env->cur_state->frame[env->cur_state->curframe]; + if (value_regno >= 0) + reg = &cur->regs[value_regno]; + if (!env->bypass_spec_v4) { + bool sanitize = reg && is_spillable_regtype(reg->type); + + for (i = 0; i < size; i++) { + u8 type = state->stack[spi].slot_type[i]; + + if (type != STACK_MISC && type != STACK_ZERO) { + sanitize = true; + break; + } + } + + if (sanitize) + env->insn_aux_data[insn_idx].sanitize_stack_spill = true; + } + + err = destroy_if_dynptr_stack_slot(env, state, spi); + if (err) + return err; + + mark_stack_slot_scratched(env, spi); + if (reg && !(off % BPF_REG_SIZE) && register_is_bounded(reg) && + !register_is_null(reg) && env->bpf_capable) { + if (dst_reg != BPF_REG_FP) { + /* The backtracking logic can only recognize explicit + * stack slot address like [fp - 8]. Other spill of + * scalar via different register has to be conservative. + * Backtrack from here and mark all registers as precise + * that contributed into 'reg' being a constant. + */ + err = mark_chain_precision(env, value_regno); + if (err) + return err; + } + save_register_state(state, spi, reg, size); + /* Break the relation on a narrowing spill. */ + if (fls64(reg->umax_value) > BITS_PER_BYTE * size) + state->stack[spi].spilled_ptr.id = 0; + } else if (!reg && !(off % BPF_REG_SIZE) && is_bpf_st_mem(insn) && + insn->imm != 0 && env->bpf_capable) { + struct bpf_reg_state fake_reg = {}; + + __mark_reg_known(&fake_reg, insn->imm); + fake_reg.type = SCALAR_VALUE; + save_register_state(state, spi, &fake_reg, size); + } else if (reg && is_spillable_regtype(reg->type)) { + /* register containing pointer is being spilled into stack */ + if (size != BPF_REG_SIZE) { + verbose_linfo(env, insn_idx, "; "); + verbose(env, "invalid size of register spill\n"); + return -EACCES; + } + if (state != cur && reg->type == PTR_TO_STACK) { + verbose(env, "cannot spill pointers to stack into stack frame of the caller\n"); + return -EINVAL; + } + save_register_state(state, spi, reg, size); + } else { + u8 type = STACK_MISC; + + /* regular write of data into stack destroys any spilled ptr */ + state->stack[spi].spilled_ptr.type = NOT_INIT; + /* Mark slots as STACK_MISC if they belonged to spilled ptr/dynptr/iter. */ + if (is_stack_slot_special(&state->stack[spi])) + for (i = 0; i < BPF_REG_SIZE; i++) + scrub_spilled_slot(&state->stack[spi].slot_type[i]); + + /* only mark the slot as written if all 8 bytes were written + * otherwise read propagation may incorrectly stop too soon + * when stack slots are partially written. + * This heuristic means that read propagation will be + * conservative, since it will add reg_live_read marks + * to stack slots all the way to first state when programs + * writes+reads less than 8 bytes + */ + if (size == BPF_REG_SIZE) + state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN; + + /* when we zero initialize stack slots mark them as such */ + if ((reg && register_is_null(reg)) || + (!reg && is_bpf_st_mem(insn) && insn->imm == 0)) { + /* backtracking doesn't work for STACK_ZERO yet. */ + err = mark_chain_precision(env, value_regno); + if (err) + return err; + type = STACK_ZERO; + } + + /* Mark slots affected by this stack write. */ + for (i = 0; i < size; i++) + state->stack[spi].slot_type[(slot - i) % BPF_REG_SIZE] = + type; + } + return 0; +} + +/* Write the stack: 'stack[ptr_regno + off] = value_regno'. 'ptr_regno' is + * known to contain a variable offset. + * This function checks whether the write is permitted and conservatively + * tracks the effects of the write, considering that each stack slot in the + * dynamic range is potentially written to. + * + * 'off' includes 'regno->off'. + * 'value_regno' can be -1, meaning that an unknown value is being written to + * the stack. + * + * Spilled pointers in range are not marked as written because we don't know + * what's going to be actually written. This means that read propagation for + * future reads cannot be terminated by this write. + * + * For privileged programs, uninitialized stack slots are considered + * initialized by this write (even though we don't know exactly what offsets + * are going to be written to). The idea is that we don't want the verifier to + * reject future reads that access slots written to through variable offsets. + */ +static int check_stack_write_var_off(struct bpf_verifier_env *env, + /* func where register points to */ + struct bpf_func_state *state, + int ptr_regno, int off, int size, + int value_regno, int insn_idx) +{ + struct bpf_func_state *cur; /* state of the current function */ + int min_off, max_off; + int i, err; + struct bpf_reg_state *ptr_reg = NULL, *value_reg = NULL; + struct bpf_insn *insn = &env->prog->insnsi[insn_idx]; + bool writing_zero = false; + /* set if the fact that we're writing a zero is used to let any + * stack slots remain STACK_ZERO + */ + bool zero_used = false; + + cur = env->cur_state->frame[env->cur_state->curframe]; + ptr_reg = &cur->regs[ptr_regno]; + min_off = ptr_reg->smin_value + off; + max_off = ptr_reg->smax_value + off + size; + if (value_regno >= 0) + value_reg = &cur->regs[value_regno]; + if ((value_reg && register_is_null(value_reg)) || + (!value_reg && is_bpf_st_mem(insn) && insn->imm == 0)) + writing_zero = true; + + for (i = min_off; i < max_off; i++) { + int spi; + + spi = __get_spi(i); + err = destroy_if_dynptr_stack_slot(env, state, spi); + if (err) + return err; + } + + /* Variable offset writes destroy any spilled pointers in range. */ + for (i = min_off; i < max_off; i++) { + u8 new_type, *stype; + int slot, spi; + + slot = -i - 1; + spi = slot / BPF_REG_SIZE; + stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE]; + mark_stack_slot_scratched(env, spi); + + if (!env->allow_ptr_leaks && *stype != STACK_MISC && *stype != STACK_ZERO) { + /* Reject the write if range we may write to has not + * been initialized beforehand. If we didn't reject + * here, the ptr status would be erased below (even + * though not all slots are actually overwritten), + * possibly opening the door to leaks. + * + * We do however catch STACK_INVALID case below, and + * only allow reading possibly uninitialized memory + * later for CAP_PERFMON, as the write may not happen to + * that slot. + */ + verbose(env, "spilled ptr in range of var-offset stack write; insn %d, ptr off: %d", + insn_idx, i); + return -EINVAL; + } + + /* Erase all spilled pointers. */ + state->stack[spi].spilled_ptr.type = NOT_INIT; + + /* Update the slot type. */ + new_type = STACK_MISC; + if (writing_zero && *stype == STACK_ZERO) { + new_type = STACK_ZERO; + zero_used = true; + } + /* If the slot is STACK_INVALID, we check whether it's OK to + * pretend that it will be initialized by this write. The slot + * might not actually be written to, and so if we mark it as + * initialized future reads might leak uninitialized memory. + * For privileged programs, we will accept such reads to slots + * that may or may not be written because, if we're reject + * them, the error would be too confusing. + */ + if (*stype == STACK_INVALID && !env->allow_uninit_stack) { + verbose(env, "uninit stack in range of var-offset write prohibited for !root; insn %d, off: %d", + insn_idx, i); + return -EINVAL; + } + *stype = new_type; + } + if (zero_used) { + /* backtracking doesn't work for STACK_ZERO yet. */ + err = mark_chain_precision(env, value_regno); + if (err) + return err; + } + return 0; +} + +/* When register 'dst_regno' is assigned some values from stack[min_off, + * max_off), we set the register's type according to the types of the + * respective stack slots. If all the stack values are known to be zeros, then + * so is the destination reg. Otherwise, the register is considered to be + * SCALAR. This function does not deal with register filling; the caller must + * ensure that all spilled registers in the stack range have been marked as + * read. + */ +static void mark_reg_stack_read(struct bpf_verifier_env *env, + /* func where src register points to */ + struct bpf_func_state *ptr_state, + int min_off, int max_off, int dst_regno) +{ + struct bpf_verifier_state *vstate = env->cur_state; + struct bpf_func_state *state = vstate->frame[vstate->curframe]; + int i, slot, spi; + u8 *stype; + int zeros = 0; + + for (i = min_off; i < max_off; i++) { + slot = -i - 1; + spi = slot / BPF_REG_SIZE; + mark_stack_slot_scratched(env, spi); + stype = ptr_state->stack[spi].slot_type; + if (stype[slot % BPF_REG_SIZE] != STACK_ZERO) + break; + zeros++; + } + if (zeros == max_off - min_off) { + /* any access_size read into register is zero extended, + * so the whole register == const_zero + */ + __mark_reg_const_zero(&state->regs[dst_regno]); + /* backtracking doesn't support STACK_ZERO yet, + * so mark it precise here, so that later + * backtracking can stop here. + * Backtracking may not need this if this register + * doesn't participate in pointer adjustment. + * Forward propagation of precise flag is not + * necessary either. This mark is only to stop + * backtracking. Any register that contributed + * to const 0 was marked precise before spill. + */ + state->regs[dst_regno].precise = true; + } else { + /* have read misc data from the stack */ + mark_reg_unknown(env, state->regs, dst_regno); + } + state->regs[dst_regno].live |= REG_LIVE_WRITTEN; +} + +/* Read the stack at 'off' and put the results into the register indicated by + * 'dst_regno'. It handles reg filling if the addressed stack slot is a + * spilled reg. + * + * 'dst_regno' can be -1, meaning that the read value is not going to a + * register. + * + * The access is assumed to be within the current stack bounds. + */ +static int check_stack_read_fixed_off(struct bpf_verifier_env *env, + /* func where src register points to */ + struct bpf_func_state *reg_state, + int off, int size, int dst_regno) +{ + struct bpf_verifier_state *vstate = env->cur_state; + struct bpf_func_state *state = vstate->frame[vstate->curframe]; + int i, slot = -off - 1, spi = slot / BPF_REG_SIZE; + struct bpf_reg_state *reg; + u8 *stype, type; + + stype = reg_state->stack[spi].slot_type; + reg = ®_state->stack[spi].spilled_ptr; + + mark_stack_slot_scratched(env, spi); + + if (is_spilled_reg(®_state->stack[spi])) { + u8 spill_size = 1; + + for (i = BPF_REG_SIZE - 1; i > 0 && stype[i - 1] == STACK_SPILL; i--) + spill_size++; + + if (size != BPF_REG_SIZE || spill_size != BPF_REG_SIZE) { + if (reg->type != SCALAR_VALUE) { + verbose_linfo(env, env->insn_idx, "; "); + verbose(env, "invalid size of register fill\n"); + return -EACCES; + } + + mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64); + if (dst_regno < 0) + return 0; + + if (!(off % BPF_REG_SIZE) && size == spill_size) { + /* The earlier check_reg_arg() has decided the + * subreg_def for this insn. Save it first. + */ + s32 subreg_def = state->regs[dst_regno].subreg_def; + + copy_register_state(&state->regs[dst_regno], reg); + state->regs[dst_regno].subreg_def = subreg_def; + } else { + for (i = 0; i < size; i++) { + type = stype[(slot - i) % BPF_REG_SIZE]; + if (type == STACK_SPILL) + continue; + if (type == STACK_MISC) + continue; + if (type == STACK_INVALID && env->allow_uninit_stack) + continue; + verbose(env, "invalid read from stack off %d+%d size %d\n", + off, i, size); + return -EACCES; + } + mark_reg_unknown(env, state->regs, dst_regno); + } + state->regs[dst_regno].live |= REG_LIVE_WRITTEN; + return 0; + } + + if (dst_regno >= 0) { + /* restore register state from stack */ + copy_register_state(&state->regs[dst_regno], reg); + /* mark reg as written since spilled pointer state likely + * has its liveness marks cleared by is_state_visited() + * which resets stack/reg liveness for state transitions + */ + state->regs[dst_regno].live |= REG_LIVE_WRITTEN; + } else if (__is_pointer_value(env->allow_ptr_leaks, reg)) { + /* If dst_regno==-1, the caller is asking us whether + * it is acceptable to use this value as a SCALAR_VALUE + * (e.g. for XADD). + * We must not allow unprivileged callers to do that + * with spilled pointers. + */ + verbose(env, "leaking pointer from stack off %d\n", + off); + return -EACCES; + } + mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64); + } else { + for (i = 0; i < size; i++) { + type = stype[(slot - i) % BPF_REG_SIZE]; + if (type == STACK_MISC) + continue; + if (type == STACK_ZERO) + continue; + if (type == STACK_INVALID && env->allow_uninit_stack) + continue; + verbose(env, "invalid read from stack off %d+%d size %d\n", + off, i, size); + return -EACCES; + } + mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64); + if (dst_regno >= 0) + mark_reg_stack_read(env, reg_state, off, off + size, dst_regno); + } + return 0; +} + +enum bpf_access_src { + ACCESS_DIRECT = 1, /* the access is performed by an instruction */ + ACCESS_HELPER = 2, /* the access is performed by a helper */ +}; + +static int check_stack_range_initialized(struct bpf_verifier_env *env, + int regno, int off, int access_size, + bool zero_size_allowed, + enum bpf_access_src type, + struct bpf_call_arg_meta *meta); + +static struct bpf_reg_state *reg_state(struct bpf_verifier_env *env, int regno) +{ + return cur_regs(env) + regno; +} + +/* Read the stack at 'ptr_regno + off' and put the result into the register + * 'dst_regno'. + * 'off' includes the pointer register's fixed offset(i.e. 'ptr_regno.off'), + * but not its variable offset. + * 'size' is assumed to be <= reg size and the access is assumed to be aligned. + * + * As opposed to check_stack_read_fixed_off, this function doesn't deal with + * filling registers (i.e. reads of spilled register cannot be detected when + * the offset is not fixed). We conservatively mark 'dst_regno' as containing + * SCALAR_VALUE. That's why we assert that the 'ptr_regno' has a variable + * offset; for a fixed offset check_stack_read_fixed_off should be used + * instead. + */ +static int check_stack_read_var_off(struct bpf_verifier_env *env, + int ptr_regno, int off, int size, int dst_regno) +{ + /* The state of the source register. */ + struct bpf_reg_state *reg = reg_state(env, ptr_regno); + struct bpf_func_state *ptr_state = func(env, reg); + int err; + int min_off, max_off; + + /* Note that we pass a NULL meta, so raw access will not be permitted. + */ + err = check_stack_range_initialized(env, ptr_regno, off, size, + false, ACCESS_DIRECT, NULL); + if (err) + return err; + + min_off = reg->smin_value + off; + max_off = reg->smax_value + off; + mark_reg_stack_read(env, ptr_state, min_off, max_off + size, dst_regno); + return 0; +} + +/* check_stack_read dispatches to check_stack_read_fixed_off or + * check_stack_read_var_off. + * + * The caller must ensure that the offset falls within the allocated stack + * bounds. + * + * 'dst_regno' is a register which will receive the value from the stack. It + * can be -1, meaning that the read value is not going to a register. + */ +static int check_stack_read(struct bpf_verifier_env *env, + int ptr_regno, int off, int size, + int dst_regno) +{ + struct bpf_reg_state *reg = reg_state(env, ptr_regno); + struct bpf_func_state *state = func(env, reg); + int err; + /* Some accesses are only permitted with a static offset. */ + bool var_off = !tnum_is_const(reg->var_off); + + /* The offset is required to be static when reads don't go to a + * register, in order to not leak pointers (see + * check_stack_read_fixed_off). + */ + if (dst_regno < 0 && var_off) { + char tn_buf[48]; + + tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); + verbose(env, "variable offset stack pointer cannot be passed into helper function; var_off=%s off=%d size=%d\n", + tn_buf, off, size); + return -EACCES; + } + /* Variable offset is prohibited for unprivileged mode for simplicity + * since it requires corresponding support in Spectre masking for stack + * ALU. See also retrieve_ptr_limit(). The check in + * check_stack_access_for_ptr_arithmetic() called by + * adjust_ptr_min_max_vals() prevents users from creating stack pointers + * with variable offsets, therefore no check is required here. Further, + * just checking it here would be insufficient as speculative stack + * writes could still lead to unsafe speculative behaviour. + */ + if (!var_off) { + off += reg->var_off.value; + err = check_stack_read_fixed_off(env, state, off, size, + dst_regno); + } else { + /* Variable offset stack reads need more conservative handling + * than fixed offset ones. Note that dst_regno >= 0 on this + * branch. + */ + err = check_stack_read_var_off(env, ptr_regno, off, size, + dst_regno); + } + return err; +} + + +/* check_stack_write dispatches to check_stack_write_fixed_off or + * check_stack_write_var_off. + * + * 'ptr_regno' is the register used as a pointer into the stack. + * 'off' includes 'ptr_regno->off', but not its variable offset (if any). + * 'value_regno' is the register whose value we're writing to the stack. It can + * be -1, meaning that we're not writing from a register. + * + * The caller must ensure that the offset falls within the maximum stack size. + */ +static int check_stack_write(struct bpf_verifier_env *env, + int ptr_regno, int off, int size, + int value_regno, int insn_idx) +{ + struct bpf_reg_state *reg = reg_state(env, ptr_regno); + struct bpf_func_state *state = func(env, reg); + int err; + + if (tnum_is_const(reg->var_off)) { + off += reg->var_off.value; + err = check_stack_write_fixed_off(env, state, off, size, + value_regno, insn_idx); + } else { + /* Variable offset stack reads need more conservative handling + * than fixed offset ones. + */ + err = check_stack_write_var_off(env, state, + ptr_regno, off, size, + value_regno, insn_idx); + } + return err; +} + +static int check_map_access_type(struct bpf_verifier_env *env, u32 regno, + int off, int size, enum bpf_access_type type) +{ + struct bpf_reg_state *regs = cur_regs(env); + struct bpf_map *map = regs[regno].map_ptr; + u32 cap = bpf_map_flags_to_cap(map); + + if (type == BPF_WRITE && !(cap & BPF_MAP_CAN_WRITE)) { + verbose(env, "write into map forbidden, value_size=%d off=%d size=%d\n", + map->value_size, off, size); + return -EACCES; + } + + if (type == BPF_READ && !(cap & BPF_MAP_CAN_READ)) { + verbose(env, "read from map forbidden, value_size=%d off=%d size=%d\n", + map->value_size, off, size); + return -EACCES; + } + + return 0; +} + +/* check read/write into memory region (e.g., map value, ringbuf sample, etc) */ +static int __check_mem_access(struct bpf_verifier_env *env, int regno, + int off, int size, u32 mem_size, + bool zero_size_allowed) +{ + bool size_ok = size > 0 || (size == 0 && zero_size_allowed); + struct bpf_reg_state *reg; + + if (off >= 0 && size_ok && (u64)off + size <= mem_size) + return 0; + + reg = &cur_regs(env)[regno]; + switch (reg->type) { + case PTR_TO_MAP_KEY: + verbose(env, "invalid access to map key, key_size=%d off=%d size=%d\n", + mem_size, off, size); + break; + case PTR_TO_MAP_VALUE: + verbose(env, "invalid access to map value, value_size=%d off=%d size=%d\n", + mem_size, off, size); + break; + case PTR_TO_PACKET: + case PTR_TO_PACKET_META: + case PTR_TO_PACKET_END: + verbose(env, "invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n", + off, size, regno, reg->id, off, mem_size); + break; + case PTR_TO_MEM: + default: + verbose(env, "invalid access to memory, mem_size=%u off=%d size=%d\n", + mem_size, off, size); + } + + return -EACCES; +} + +/* check read/write into a memory region with possible variable offset */ +static int check_mem_region_access(struct bpf_verifier_env *env, u32 regno, + int off, int size, u32 mem_size, + bool zero_size_allowed) +{ + struct bpf_verifier_state *vstate = env->cur_state; + struct bpf_func_state *state = vstate->frame[vstate->curframe]; + struct bpf_reg_state *reg = &state->regs[regno]; + int err; + + /* We may have adjusted the register pointing to memory region, so we + * need to try adding each of min_value and max_value to off + * to make sure our theoretical access will be safe. + * + * The minimum value is only important with signed + * comparisons where we can't assume the floor of a + * value is 0. If we are using signed variables for our + * index'es we need to make sure that whatever we use + * will have a set floor within our range. + */ + if (reg->smin_value < 0 && + (reg->smin_value == S64_MIN || + (off + reg->smin_value != (s64)(s32)(off + reg->smin_value)) || + reg->smin_value + off < 0)) { + verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n", + regno); + return -EACCES; + } + err = __check_mem_access(env, regno, reg->smin_value + off, size, + mem_size, zero_size_allowed); + if (err) { + verbose(env, "R%d min value is outside of the allowed memory range\n", + regno); + return err; + } + + /* If we haven't set a max value then we need to bail since we can't be + * sure we won't do bad things. + * If reg->umax_value + off could overflow, treat that as unbounded too. + */ + if (reg->umax_value >= BPF_MAX_VAR_OFF) { + verbose(env, "R%d unbounded memory access, make sure to bounds check any such access\n", + regno); + return -EACCES; + } + err = __check_mem_access(env, regno, reg->umax_value + off, size, + mem_size, zero_size_allowed); + if (err) { + verbose(env, "R%d max value is outside of the allowed memory range\n", + regno); + return err; + } + + return 0; +} + +static int __check_ptr_off_reg(struct bpf_verifier_env *env, + const struct bpf_reg_state *reg, int regno, + bool fixed_off_ok) +{ + /* Access to this pointer-typed register or passing it to a helper + * is only allowed in its original, unmodified form. + */ + + if (reg->off < 0) { + verbose(env, "negative offset %s ptr R%d off=%d disallowed\n", + reg_type_str(env, reg->type), regno, reg->off); + return -EACCES; + } + + if (!fixed_off_ok && reg->off) { + verbose(env, "dereference of modified %s ptr R%d off=%d disallowed\n", + reg_type_str(env, reg->type), regno, reg->off); + return -EACCES; + } + + if (!tnum_is_const(reg->var_off) || reg->var_off.value) { + char tn_buf[48]; + + tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); + verbose(env, "variable %s access var_off=%s disallowed\n", + reg_type_str(env, reg->type), tn_buf); + return -EACCES; + } + + return 0; +} + +int check_ptr_off_reg(struct bpf_verifier_env *env, + const struct bpf_reg_state *reg, int regno) +{ + return __check_ptr_off_reg(env, reg, regno, false); +} + +static int map_kptr_match_type(struct bpf_verifier_env *env, + struct btf_field *kptr_field, + struct bpf_reg_state *reg, u32 regno) +{ + const char *targ_name = btf_type_name(kptr_field->kptr.btf, kptr_field->kptr.btf_id); + int perm_flags; + const char *reg_name = ""; + + if (btf_is_kernel(reg->btf)) { + perm_flags = PTR_MAYBE_NULL | PTR_TRUSTED | MEM_RCU; + + /* Only unreferenced case accepts untrusted pointers */ + if (kptr_field->type == BPF_KPTR_UNREF) + perm_flags |= PTR_UNTRUSTED; + } else { + perm_flags = PTR_MAYBE_NULL | MEM_ALLOC; + } + + if (base_type(reg->type) != PTR_TO_BTF_ID || (type_flag(reg->type) & ~perm_flags)) + goto bad_type; + + /* We need to verify reg->type and reg->btf, before accessing reg->btf */ + reg_name = btf_type_name(reg->btf, reg->btf_id); + + /* For ref_ptr case, release function check should ensure we get one + * referenced PTR_TO_BTF_ID, and that its fixed offset is 0. For the + * normal store of unreferenced kptr, we must ensure var_off is zero. + * Since ref_ptr cannot be accessed directly by BPF insns, checks for + * reg->off and reg->ref_obj_id are not needed here. + */ + if (__check_ptr_off_reg(env, reg, regno, true)) + return -EACCES; + + /* A full type match is needed, as BTF can be vmlinux, module or prog BTF, and + * we also need to take into account the reg->off. + * + * We want to support cases like: + * + * struct foo { + * struct bar br; + * struct baz bz; + * }; + * + * struct foo *v; + * v = func(); // PTR_TO_BTF_ID + * val->foo = v; // reg->off is zero, btf and btf_id match type + * val->bar = &v->br; // reg->off is still zero, but we need to retry with + * // first member type of struct after comparison fails + * val->baz = &v->bz; // reg->off is non-zero, so struct needs to be walked + * // to match type + * + * In the kptr_ref case, check_func_arg_reg_off already ensures reg->off + * is zero. We must also ensure that btf_struct_ids_match does not walk + * the struct to match type against first member of struct, i.e. reject + * second case from above. Hence, when type is BPF_KPTR_REF, we set + * strict mode to true for type match. + */ + if (!btf_struct_ids_match(&env->log, reg->btf, reg->btf_id, reg->off, + kptr_field->kptr.btf, kptr_field->kptr.btf_id, + kptr_field->type == BPF_KPTR_REF)) + goto bad_type; + return 0; +bad_type: + verbose(env, "invalid kptr access, R%d type=%s%s ", regno, + reg_type_str(env, reg->type), reg_name); + verbose(env, "expected=%s%s", reg_type_str(env, PTR_TO_BTF_ID), targ_name); + if (kptr_field->type == BPF_KPTR_UNREF) + verbose(env, " or %s%s\n", reg_type_str(env, PTR_TO_BTF_ID | PTR_UNTRUSTED), + targ_name); + else + verbose(env, "\n"); + return -EINVAL; +} + +/* The non-sleepable programs and sleepable programs with explicit bpf_rcu_read_lock() + * can dereference RCU protected pointers and result is PTR_TRUSTED. + */ +static bool in_rcu_cs(struct bpf_verifier_env *env) +{ + return env->cur_state->active_rcu_lock || + env->cur_state->active_lock.ptr || + !env->prog->aux->sleepable; +} + +/* Once GCC supports btf_type_tag the following mechanism will be replaced with tag check */ +BTF_SET_START(rcu_protected_types) +BTF_ID(struct, prog_test_ref_kfunc) +BTF_ID(struct, cgroup) +BTF_ID(struct, bpf_cpumask) +BTF_ID(struct, task_struct) +BTF_SET_END(rcu_protected_types) + +static bool rcu_protected_object(const struct btf *btf, u32 btf_id) +{ + if (!btf_is_kernel(btf)) + return false; + return btf_id_set_contains(&rcu_protected_types, btf_id); +} + +static bool rcu_safe_kptr(const struct btf_field *field) +{ + const struct btf_field_kptr *kptr = &field->kptr; + + return field->type == BPF_KPTR_REF && rcu_protected_object(kptr->btf, kptr->btf_id); +} + +static int check_map_kptr_access(struct bpf_verifier_env *env, u32 regno, + int value_regno, int insn_idx, + struct btf_field *kptr_field) +{ + struct bpf_insn *insn = &env->prog->insnsi[insn_idx]; + int class = BPF_CLASS(insn->code); + struct bpf_reg_state *val_reg; + + /* Things we already checked for in check_map_access and caller: + * - Reject cases where variable offset may touch kptr + * - size of access (must be BPF_DW) + * - tnum_is_const(reg->var_off) + * - kptr_field->offset == off + reg->var_off.value + */ + /* Only BPF_[LDX,STX,ST] | BPF_MEM | BPF_DW is supported */ + if (BPF_MODE(insn->code) != BPF_MEM) { + verbose(env, "kptr in map can only be accessed using BPF_MEM instruction mode\n"); + return -EACCES; + } + + /* We only allow loading referenced kptr, since it will be marked as + * untrusted, similar to unreferenced kptr. + */ + if (class != BPF_LDX && kptr_field->type == BPF_KPTR_REF) { + verbose(env, "store to referenced kptr disallowed\n"); + return -EACCES; + } + + if (class == BPF_LDX) { + val_reg = reg_state(env, value_regno); + /* We can simply mark the value_regno receiving the pointer + * value from map as PTR_TO_BTF_ID, with the correct type. + */ + mark_btf_ld_reg(env, cur_regs(env), value_regno, PTR_TO_BTF_ID, kptr_field->kptr.btf, + kptr_field->kptr.btf_id, + rcu_safe_kptr(kptr_field) && in_rcu_cs(env) ? + PTR_MAYBE_NULL | MEM_RCU : + PTR_MAYBE_NULL | PTR_UNTRUSTED); + /* For mark_ptr_or_null_reg */ + val_reg->id = ++env->id_gen; + } else if (class == BPF_STX) { + val_reg = reg_state(env, value_regno); + if (!register_is_null(val_reg) && + map_kptr_match_type(env, kptr_field, val_reg, value_regno)) + return -EACCES; + } else if (class == BPF_ST) { + if (insn->imm) { + verbose(env, "BPF_ST imm must be 0 when storing to kptr at off=%u\n", + kptr_field->offset); + return -EACCES; + } + } else { + verbose(env, "kptr in map can only be accessed using BPF_LDX/BPF_STX/BPF_ST\n"); + return -EACCES; + } + return 0; +} + +/* check read/write into a map element with possible variable offset */ +static int check_map_access(struct bpf_verifier_env *env, u32 regno, + int off, int size, bool zero_size_allowed, + enum bpf_access_src src) +{ + struct bpf_verifier_state *vstate = env->cur_state; + struct bpf_func_state *state = vstate->frame[vstate->curframe]; + struct bpf_reg_state *reg = &state->regs[regno]; + struct bpf_map *map = reg->map_ptr; + struct btf_record *rec; + int err, i; + + err = check_mem_region_access(env, regno, off, size, map->value_size, + zero_size_allowed); + if (err) + return err; + + if (IS_ERR_OR_NULL(map->record)) + return 0; + rec = map->record; + for (i = 0; i < rec->cnt; i++) { + struct btf_field *field = &rec->fields[i]; + u32 p = field->offset; + + /* If any part of a field can be touched by load/store, reject + * this program. To check that [x1, x2) overlaps with [y1, y2), + * it is sufficient to check x1 < y2 && y1 < x2. + */ + if (reg->smin_value + off < p + btf_field_type_size(field->type) && + p < reg->umax_value + off + size) { + switch (field->type) { + case BPF_KPTR_UNREF: + case BPF_KPTR_REF: + if (src != ACCESS_DIRECT) { + verbose(env, "kptr cannot be accessed indirectly by helper\n"); + return -EACCES; + } + if (!tnum_is_const(reg->var_off)) { + verbose(env, "kptr access cannot have variable offset\n"); + return -EACCES; + } + if (p != off + reg->var_off.value) { + verbose(env, "kptr access misaligned expected=%u off=%llu\n", + p, off + reg->var_off.value); + return -EACCES; + } + if (size != bpf_size_to_bytes(BPF_DW)) { + verbose(env, "kptr access size must be BPF_DW\n"); + return -EACCES; + } + break; + default: + verbose(env, "%s cannot be accessed directly by load/store\n", + btf_field_type_name(field->type)); + return -EACCES; + } + } + } + return 0; +} + +#define MAX_PACKET_OFF 0xffff + +static bool may_access_direct_pkt_data(struct bpf_verifier_env *env, + const struct bpf_call_arg_meta *meta, + enum bpf_access_type t) +{ + enum bpf_prog_type prog_type = resolve_prog_type(env->prog); + + switch (prog_type) { + /* Program types only with direct read access go here! */ + case BPF_PROG_TYPE_LWT_IN: + case BPF_PROG_TYPE_LWT_OUT: + case BPF_PROG_TYPE_LWT_SEG6LOCAL: + case BPF_PROG_TYPE_SK_REUSEPORT: + case BPF_PROG_TYPE_FLOW_DISSECTOR: + case BPF_PROG_TYPE_CGROUP_SKB: + if (t == BPF_WRITE) + return false; + fallthrough; + + /* Program types with direct read + write access go here! */ + case BPF_PROG_TYPE_SCHED_CLS: + case BPF_PROG_TYPE_SCHED_ACT: + case BPF_PROG_TYPE_XDP: + case BPF_PROG_TYPE_LWT_XMIT: + case BPF_PROG_TYPE_SK_SKB: + case BPF_PROG_TYPE_SK_MSG: + if (meta) + return meta->pkt_access; + + env->seen_direct_write = true; + return true; + + case BPF_PROG_TYPE_CGROUP_SOCKOPT: + if (t == BPF_WRITE) + env->seen_direct_write = true; + + return true; + + default: + return false; + } +} + +static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off, + int size, bool zero_size_allowed) +{ + struct bpf_reg_state *regs = cur_regs(env); + struct bpf_reg_state *reg = ®s[regno]; + int err; + + /* We may have added a variable offset to the packet pointer; but any + * reg->range we have comes after that. We are only checking the fixed + * offset. + */ + + /* We don't allow negative numbers, because we aren't tracking enough + * detail to prove they're safe. + */ + if (reg->smin_value < 0) { + verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n", + regno); + return -EACCES; + } + + err = reg->range < 0 ? -EINVAL : + __check_mem_access(env, regno, off, size, reg->range, + zero_size_allowed); + if (err) { + verbose(env, "R%d offset is outside of the packet\n", regno); + return err; + } + + /* __check_mem_access has made sure "off + size - 1" is within u16. + * reg->umax_value can't be bigger than MAX_PACKET_OFF which is 0xffff, + * otherwise find_good_pkt_pointers would have refused to set range info + * that __check_mem_access would have rejected this pkt access. + * Therefore, "off + reg->umax_value + size - 1" won't overflow u32. + */ + env->prog->aux->max_pkt_offset = + max_t(u32, env->prog->aux->max_pkt_offset, + off + reg->umax_value + size - 1); + + return err; +} + +/* check access to 'struct bpf_context' fields. Supports fixed offsets only */ +static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, int size, + enum bpf_access_type t, enum bpf_reg_type *reg_type, + struct btf **btf, u32 *btf_id) +{ + struct bpf_insn_access_aux info = { + .reg_type = *reg_type, + .log = &env->log, + }; + + if (env->ops->is_valid_access && + env->ops->is_valid_access(off, size, t, env->prog, &info)) { + /* A non zero info.ctx_field_size indicates that this field is a + * candidate for later verifier transformation to load the whole + * field and then apply a mask when accessed with a narrower + * access than actual ctx access size. A zero info.ctx_field_size + * will only allow for whole field access and rejects any other + * type of narrower access. + */ + *reg_type = info.reg_type; + + if (base_type(*reg_type) == PTR_TO_BTF_ID) { + *btf = info.btf; + *btf_id = info.btf_id; + } else { + env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size; + } + /* remember the offset of last byte accessed in ctx */ + if (env->prog->aux->max_ctx_offset < off + size) + env->prog->aux->max_ctx_offset = off + size; + return 0; + } + + verbose(env, "invalid bpf_context access off=%d size=%d\n", off, size); + return -EACCES; +} + +static int check_flow_keys_access(struct bpf_verifier_env *env, int off, + int size) +{ + if (size < 0 || off < 0 || + (u64)off + size > sizeof(struct bpf_flow_keys)) { + verbose(env, "invalid access to flow keys off=%d size=%d\n", + off, size); + return -EACCES; + } + return 0; +} + +static int check_sock_access(struct bpf_verifier_env *env, int insn_idx, + u32 regno, int off, int size, + enum bpf_access_type t) +{ + struct bpf_reg_state *regs = cur_regs(env); + struct bpf_reg_state *reg = ®s[regno]; + struct bpf_insn_access_aux info = {}; + bool valid; + + if (reg->smin_value < 0) { + verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n", + regno); + return -EACCES; + } + + switch (reg->type) { + case PTR_TO_SOCK_COMMON: + valid = bpf_sock_common_is_valid_access(off, size, t, &info); + break; + case PTR_TO_SOCKET: + valid = bpf_sock_is_valid_access(off, size, t, &info); + break; + case PTR_TO_TCP_SOCK: + valid = bpf_tcp_sock_is_valid_access(off, size, t, &info); + break; + case PTR_TO_XDP_SOCK: + valid = bpf_xdp_sock_is_valid_access(off, size, t, &info); + break; + default: + valid = false; + } + + + if (valid) { + env->insn_aux_data[insn_idx].ctx_field_size = + info.ctx_field_size; + return 0; + } + + verbose(env, "R%d invalid %s access off=%d size=%d\n", + regno, reg_type_str(env, reg->type), off, size); + + return -EACCES; +} + +static bool is_pointer_value(struct bpf_verifier_env *env, int regno) +{ + return __is_pointer_value(env->allow_ptr_leaks, reg_state(env, regno)); +} + +static bool is_ctx_reg(struct bpf_verifier_env *env, int regno) +{ + const struct bpf_reg_state *reg = reg_state(env, regno); + + return reg->type == PTR_TO_CTX; +} + +static bool is_sk_reg(struct bpf_verifier_env *env, int regno) +{ + const struct bpf_reg_state *reg = reg_state(env, regno); + + return type_is_sk_pointer(reg->type); +} + +static bool is_pkt_reg(struct bpf_verifier_env *env, int regno) +{ + const struct bpf_reg_state *reg = reg_state(env, regno); + + return type_is_pkt_pointer(reg->type); +} + +static bool is_flow_key_reg(struct bpf_verifier_env *env, int regno) +{ + const struct bpf_reg_state *reg = reg_state(env, regno); + + /* Separate to is_ctx_reg() since we still want to allow BPF_ST here. */ + return reg->type == PTR_TO_FLOW_KEYS; +} + +static u32 *reg2btf_ids[__BPF_REG_TYPE_MAX] = { +#ifdef CONFIG_NET + [PTR_TO_SOCKET] = &btf_sock_ids[BTF_SOCK_TYPE_SOCK], + [PTR_TO_SOCK_COMMON] = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON], + [PTR_TO_TCP_SOCK] = &btf_sock_ids[BTF_SOCK_TYPE_TCP], +#endif + [CONST_PTR_TO_MAP] = btf_bpf_map_id, +}; + +static bool is_trusted_reg(const struct bpf_reg_state *reg) +{ + /* A referenced register is always trusted. */ + if (reg->ref_obj_id) + return true; + + /* Types listed in the reg2btf_ids are always trusted */ + if (reg2btf_ids[base_type(reg->type)]) + return true; + + /* If a register is not referenced, it is trusted if it has the + * MEM_ALLOC or PTR_TRUSTED type modifiers, and no others. Some of the + * other type modifiers may be safe, but we elect to take an opt-in + * approach here as some (e.g. PTR_UNTRUSTED and PTR_MAYBE_NULL) are + * not. + * + * Eventually, we should make PTR_TRUSTED the single source of truth + * for whether a register is trusted. + */ + return type_flag(reg->type) & BPF_REG_TRUSTED_MODIFIERS && + !bpf_type_has_unsafe_modifiers(reg->type); +} + +static bool is_rcu_reg(const struct bpf_reg_state *reg) +{ + return reg->type & MEM_RCU; +} + +static void clear_trusted_flags(enum bpf_type_flag *flag) +{ + *flag &= ~(BPF_REG_TRUSTED_MODIFIERS | MEM_RCU); +} + +static int check_pkt_ptr_alignment(struct bpf_verifier_env *env, + const struct bpf_reg_state *reg, + int off, int size, bool strict) +{ + struct tnum reg_off; + int ip_align; + + /* Byte size accesses are always allowed. */ + if (!strict || size == 1) + return 0; + + /* For platforms that do not have a Kconfig enabling + * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of + * NET_IP_ALIGN is universally set to '2'. And on platforms + * that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get + * to this code only in strict mode where we want to emulate + * the NET_IP_ALIGN==2 checking. Therefore use an + * unconditional IP align value of '2'. + */ + ip_align = 2; + + reg_off = tnum_add(reg->var_off, tnum_const(ip_align + reg->off + off)); + if (!tnum_is_aligned(reg_off, size)) { + char tn_buf[48]; + + tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); + verbose(env, + "misaligned packet access off %d+%s+%d+%d size %d\n", + ip_align, tn_buf, reg->off, off, size); + return -EACCES; + } + + return 0; +} + +static int check_generic_ptr_alignment(struct bpf_verifier_env *env, + const struct bpf_reg_state *reg, + const char *pointer_desc, + int off, int size, bool strict) +{ + struct tnum reg_off; + + /* Byte size accesses are always allowed. */ + if (!strict || size == 1) + return 0; + + reg_off = tnum_add(reg->var_off, tnum_const(reg->off + off)); + if (!tnum_is_aligned(reg_off, size)) { + char tn_buf[48]; + + tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); + verbose(env, "misaligned %saccess off %s+%d+%d size %d\n", + pointer_desc, tn_buf, reg->off, off, size); + return -EACCES; + } + + return 0; +} + +static int check_ptr_alignment(struct bpf_verifier_env *env, + const struct bpf_reg_state *reg, int off, + int size, bool strict_alignment_once) +{ + bool strict = env->strict_alignment || strict_alignment_once; + const char *pointer_desc = ""; + + switch (reg->type) { + case PTR_TO_PACKET: + case PTR_TO_PACKET_META: + /* Special case, because of NET_IP_ALIGN. Given metadata sits + * right in front, treat it the very same way. + */ + return check_pkt_ptr_alignment(env, reg, off, size, strict); + case PTR_TO_FLOW_KEYS: + pointer_desc = "flow keys "; + break; + case PTR_TO_MAP_KEY: + pointer_desc = "key "; + break; + case PTR_TO_MAP_VALUE: + pointer_desc = "value "; + break; + case PTR_TO_CTX: + pointer_desc = "context "; + break; + case PTR_TO_STACK: + pointer_desc = "stack "; + /* The stack spill tracking logic in check_stack_write_fixed_off() + * and check_stack_read_fixed_off() relies on stack accesses being + * aligned. + */ + strict = true; + break; + case PTR_TO_SOCKET: + pointer_desc = "sock "; + break; + case PTR_TO_SOCK_COMMON: + pointer_desc = "sock_common "; + break; + case PTR_TO_TCP_SOCK: + pointer_desc = "tcp_sock "; + break; + case PTR_TO_XDP_SOCK: + pointer_desc = "xdp_sock "; + break; + default: + break; + } + return check_generic_ptr_alignment(env, reg, pointer_desc, off, size, + strict); +} + +/* starting from main bpf function walk all instructions of the function + * and recursively walk all callees that given function can call. + * Ignore jump and exit insns. + * Since recursion is prevented by check_cfg() this algorithm + * only needs a local stack of MAX_CALL_FRAMES to remember callsites + */ +static int check_max_stack_depth_subprog(struct bpf_verifier_env *env, int idx) +{ + struct bpf_subprog_info *subprog = env->subprog_info; + struct bpf_insn *insn = env->prog->insnsi; + int depth = 0, frame = 0, i, subprog_end; + bool tail_call_reachable = false; + int ret_insn[MAX_CALL_FRAMES]; + int ret_prog[MAX_CALL_FRAMES]; + int j; + + i = subprog[idx].start; +process_func: + /* protect against potential stack overflow that might happen when + * bpf2bpf calls get combined with tailcalls. Limit the caller's stack + * depth for such case down to 256 so that the worst case scenario + * would result in 8k stack size (32 which is tailcall limit * 256 = + * 8k). + * + * To get the idea what might happen, see an example: + * func1 -> sub rsp, 128 + * subfunc1 -> sub rsp, 256 + * tailcall1 -> add rsp, 256 + * func2 -> sub rsp, 192 (total stack size = 128 + 192 = 320) + * subfunc2 -> sub rsp, 64 + * subfunc22 -> sub rsp, 128 + * tailcall2 -> add rsp, 128 + * func3 -> sub rsp, 32 (total stack size 128 + 192 + 64 + 32 = 416) + * + * tailcall will unwind the current stack frame but it will not get rid + * of caller's stack as shown on the example above. + */ + if (idx && subprog[idx].has_tail_call && depth >= 256) { + verbose(env, + "tail_calls are not allowed when call stack of previous frames is %d bytes. Too large\n", + depth); + return -EACCES; + } + /* round up to 32-bytes, since this is granularity + * of interpreter stack size + */ + depth += round_up(max_t(u32, subprog[idx].stack_depth, 1), 32); + if (depth > MAX_BPF_STACK) { + verbose(env, "combined stack size of %d calls is %d. Too large\n", + frame + 1, depth); + return -EACCES; + } +continue_func: + subprog_end = subprog[idx + 1].start; + for (; i < subprog_end; i++) { + int next_insn, sidx; + + if (!bpf_pseudo_call(insn + i) && !bpf_pseudo_func(insn + i)) + continue; + /* remember insn and function to return to */ + ret_insn[frame] = i + 1; + ret_prog[frame] = idx; + + /* find the callee */ + next_insn = i + insn[i].imm + 1; + sidx = find_subprog(env, next_insn); + if (sidx < 0) { + WARN_ONCE(1, "verifier bug. No program starts at insn %d\n", + next_insn); + return -EFAULT; + } + if (subprog[sidx].is_async_cb) { + if (subprog[sidx].has_tail_call) { + verbose(env, "verifier bug. subprog has tail_call and async cb\n"); + return -EFAULT; + } + /* async callbacks don't increase bpf prog stack size unless called directly */ + if (!bpf_pseudo_call(insn + i)) + continue; + } + i = next_insn; + idx = sidx; + + if (subprog[idx].has_tail_call) + tail_call_reachable = true; + + frame++; + if (frame >= MAX_CALL_FRAMES) { + verbose(env, "the call stack of %d frames is too deep !\n", + frame); + return -E2BIG; + } + goto process_func; + } + /* if tail call got detected across bpf2bpf calls then mark each of the + * currently present subprog frames as tail call reachable subprogs; + * this info will be utilized by JIT so that we will be preserving the + * tail call counter throughout bpf2bpf calls combined with tailcalls + */ + if (tail_call_reachable) + for (j = 0; j < frame; j++) + subprog[ret_prog[j]].tail_call_reachable = true; + if (subprog[0].tail_call_reachable) + env->prog->aux->tail_call_reachable = true; + + /* end of for() loop means the last insn of the 'subprog' + * was reached. Doesn't matter whether it was JA or EXIT + */ + if (frame == 0) + return 0; + depth -= round_up(max_t(u32, subprog[idx].stack_depth, 1), 32); + frame--; + i = ret_insn[frame]; + idx = ret_prog[frame]; + goto continue_func; +} + +static int check_max_stack_depth(struct bpf_verifier_env *env) +{ + struct bpf_subprog_info *si = env->subprog_info; + int ret; + + for (int i = 0; i < env->subprog_cnt; i++) { + if (!i || si[i].is_async_cb) { + ret = check_max_stack_depth_subprog(env, i); + if (ret < 0) + return ret; + } + continue; + } + return 0; +} + +#ifndef CONFIG_BPF_JIT_ALWAYS_ON +static int get_callee_stack_depth(struct bpf_verifier_env *env, + const struct bpf_insn *insn, int idx) +{ + int start = idx + insn->imm + 1, subprog; + + subprog = find_subprog(env, start); + if (subprog < 0) { + WARN_ONCE(1, "verifier bug. No program starts at insn %d\n", + start); + return -EFAULT; + } + return env->subprog_info[subprog].stack_depth; +} +#endif + +static int __check_buffer_access(struct bpf_verifier_env *env, + const char *buf_info, + const struct bpf_reg_state *reg, + int regno, int off, int size) +{ + if (off < 0) { + verbose(env, + "R%d invalid %s buffer access: off=%d, size=%d\n", + regno, buf_info, off, size); + return -EACCES; + } + if (!tnum_is_const(reg->var_off) || reg->var_off.value) { + char tn_buf[48]; + + tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); + verbose(env, + "R%d invalid variable buffer offset: off=%d, var_off=%s\n", + regno, off, tn_buf); + return -EACCES; + } + + return 0; +} + +static int check_tp_buffer_access(struct bpf_verifier_env *env, + const struct bpf_reg_state *reg, + int regno, int off, int size) +{ + int err; + + err = __check_buffer_access(env, "tracepoint", reg, regno, off, size); + if (err) + return err; + + if (off + size > env->prog->aux->max_tp_access) + env->prog->aux->max_tp_access = off + size; + + return 0; +} + +static int check_buffer_access(struct bpf_verifier_env *env, + const struct bpf_reg_state *reg, + int regno, int off, int size, + bool zero_size_allowed, + u32 *max_access) +{ + const char *buf_info = type_is_rdonly_mem(reg->type) ? "rdonly" : "rdwr"; + int err; + + err = __check_buffer_access(env, buf_info, reg, regno, off, size); + if (err) + return err; + + if (off + size > *max_access) + *max_access = off + size; + + return 0; +} + +/* BPF architecture zero extends alu32 ops into 64-bit registesr */ +static void zext_32_to_64(struct bpf_reg_state *reg) +{ + reg->var_off = tnum_subreg(reg->var_off); + __reg_assign_32_into_64(reg); +} + +/* truncate register to smaller size (in bytes) + * must be called with size < BPF_REG_SIZE + */ +static void coerce_reg_to_size(struct bpf_reg_state *reg, int size) +{ + u64 mask; + + /* clear high bits in bit representation */ + reg->var_off = tnum_cast(reg->var_off, size); + + /* fix arithmetic bounds */ + mask = ((u64)1 << (size * 8)) - 1; + if ((reg->umin_value & ~mask) == (reg->umax_value & ~mask)) { + reg->umin_value &= mask; + reg->umax_value &= mask; + } else { + reg->umin_value = 0; + reg->umax_value = mask; + } + reg->smin_value = reg->umin_value; + reg->smax_value = reg->umax_value; + + /* If size is smaller than 32bit register the 32bit register + * values are also truncated so we push 64-bit bounds into + * 32-bit bounds. Above were truncated < 32-bits already. + */ + if (size >= 4) + return; + __reg_combine_64_into_32(reg); +} + +static void set_sext64_default_val(struct bpf_reg_state *reg, int size) +{ + if (size == 1) { + reg->smin_value = reg->s32_min_value = S8_MIN; + reg->smax_value = reg->s32_max_value = S8_MAX; + } else if (size == 2) { + reg->smin_value = reg->s32_min_value = S16_MIN; + reg->smax_value = reg->s32_max_value = S16_MAX; + } else { + /* size == 4 */ + reg->smin_value = reg->s32_min_value = S32_MIN; + reg->smax_value = reg->s32_max_value = S32_MAX; + } + reg->umin_value = reg->u32_min_value = 0; + reg->umax_value = U64_MAX; + reg->u32_max_value = U32_MAX; + reg->var_off = tnum_unknown; +} + +static void coerce_reg_to_size_sx(struct bpf_reg_state *reg, int size) +{ + s64 init_s64_max, init_s64_min, s64_max, s64_min, u64_cval; + u64 top_smax_value, top_smin_value; + u64 num_bits = size * 8; + + if (tnum_is_const(reg->var_off)) { + u64_cval = reg->var_off.value; + if (size == 1) + reg->var_off = tnum_const((s8)u64_cval); + else if (size == 2) + reg->var_off = tnum_const((s16)u64_cval); + else + /* size == 4 */ + reg->var_off = tnum_const((s32)u64_cval); + + u64_cval = reg->var_off.value; + reg->smax_value = reg->smin_value = u64_cval; + reg->umax_value = reg->umin_value = u64_cval; + reg->s32_max_value = reg->s32_min_value = u64_cval; + reg->u32_max_value = reg->u32_min_value = u64_cval; + return; + } + + top_smax_value = ((u64)reg->smax_value >> num_bits) << num_bits; + top_smin_value = ((u64)reg->smin_value >> num_bits) << num_bits; + + if (top_smax_value != top_smin_value) + goto out; + + /* find the s64_min and s64_min after sign extension */ + if (size == 1) { + init_s64_max = (s8)reg->smax_value; + init_s64_min = (s8)reg->smin_value; + } else if (size == 2) { + init_s64_max = (s16)reg->smax_value; + init_s64_min = (s16)reg->smin_value; + } else { + init_s64_max = (s32)reg->smax_value; + init_s64_min = (s32)reg->smin_value; + } + + s64_max = max(init_s64_max, init_s64_min); + s64_min = min(init_s64_max, init_s64_min); + + /* both of s64_max/s64_min positive or negative */ + if ((s64_max >= 0) == (s64_min >= 0)) { + reg->smin_value = reg->s32_min_value = s64_min; + reg->smax_value = reg->s32_max_value = s64_max; + reg->umin_value = reg->u32_min_value = s64_min; + reg->umax_value = reg->u32_max_value = s64_max; + reg->var_off = tnum_range(s64_min, s64_max); + return; + } + +out: + set_sext64_default_val(reg, size); +} + +static void set_sext32_default_val(struct bpf_reg_state *reg, int size) +{ + if (size == 1) { + reg->s32_min_value = S8_MIN; + reg->s32_max_value = S8_MAX; + } else { + /* size == 2 */ + reg->s32_min_value = S16_MIN; + reg->s32_max_value = S16_MAX; + } + reg->u32_min_value = 0; + reg->u32_max_value = U32_MAX; +} + +static void coerce_subreg_to_size_sx(struct bpf_reg_state *reg, int size) +{ + s32 init_s32_max, init_s32_min, s32_max, s32_min, u32_val; + u32 top_smax_value, top_smin_value; + u32 num_bits = size * 8; + + if (tnum_is_const(reg->var_off)) { + u32_val = reg->var_off.value; + if (size == 1) + reg->var_off = tnum_const((s8)u32_val); + else + reg->var_off = tnum_const((s16)u32_val); + + u32_val = reg->var_off.value; + reg->s32_min_value = reg->s32_max_value = u32_val; + reg->u32_min_value = reg->u32_max_value = u32_val; + return; + } + + top_smax_value = ((u32)reg->s32_max_value >> num_bits) << num_bits; + top_smin_value = ((u32)reg->s32_min_value >> num_bits) << num_bits; + + if (top_smax_value != top_smin_value) + goto out; + + /* find the s32_min and s32_min after sign extension */ + if (size == 1) { + init_s32_max = (s8)reg->s32_max_value; + init_s32_min = (s8)reg->s32_min_value; + } else { + /* size == 2 */ + init_s32_max = (s16)reg->s32_max_value; + init_s32_min = (s16)reg->s32_min_value; + } + s32_max = max(init_s32_max, init_s32_min); + s32_min = min(init_s32_max, init_s32_min); + + if ((s32_min >= 0) == (s32_max >= 0)) { + reg->s32_min_value = s32_min; + reg->s32_max_value = s32_max; + reg->u32_min_value = (u32)s32_min; + reg->u32_max_value = (u32)s32_max; + return; + } + +out: + set_sext32_default_val(reg, size); +} + +static bool bpf_map_is_rdonly(const struct bpf_map *map) +{ + /* A map is considered read-only if the following condition are true: + * + * 1) BPF program side cannot change any of the map content. The + * BPF_F_RDONLY_PROG flag is throughout the lifetime of a map + * and was set at map creation time. + * 2) The map value(s) have been initialized from user space by a + * loader and then "frozen", such that no new map update/delete + * operations from syscall side are possible for the rest of + * the map's lifetime from that point onwards. + * 3) Any parallel/pending map update/delete operations from syscall + * side have been completed. Only after that point, it's safe to + * assume that map value(s) are immutable. + */ + return (map->map_flags & BPF_F_RDONLY_PROG) && + READ_ONCE(map->frozen) && + !bpf_map_write_active(map); +} + +static int bpf_map_direct_read(struct bpf_map *map, int off, int size, u64 *val, + bool is_ldsx) +{ + void *ptr; + u64 addr; + int err; + + err = map->ops->map_direct_value_addr(map, &addr, off); + if (err) + return err; + ptr = (void *)(long)addr + off; + + switch (size) { + case sizeof(u8): + *val = is_ldsx ? (s64)*(s8 *)ptr : (u64)*(u8 *)ptr; + break; + case sizeof(u16): + *val = is_ldsx ? (s64)*(s16 *)ptr : (u64)*(u16 *)ptr; + break; + case sizeof(u32): + *val = is_ldsx ? (s64)*(s32 *)ptr : (u64)*(u32 *)ptr; + break; + case sizeof(u64): + *val = *(u64 *)ptr; + break; + default: + return -EINVAL; + } + return 0; +} + +#define BTF_TYPE_SAFE_RCU(__type) __PASTE(__type, __safe_rcu) +#define BTF_TYPE_SAFE_RCU_OR_NULL(__type) __PASTE(__type, __safe_rcu_or_null) +#define BTF_TYPE_SAFE_TRUSTED(__type) __PASTE(__type, __safe_trusted) + +/* + * Allow list few fields as RCU trusted or full trusted. + * This logic doesn't allow mix tagging and will be removed once GCC supports + * btf_type_tag. + */ + +/* RCU trusted: these fields are trusted in RCU CS and never NULL */ +BTF_TYPE_SAFE_RCU(struct task_struct) { + const cpumask_t *cpus_ptr; + struct css_set __rcu *cgroups; + struct task_struct __rcu *real_parent; + struct task_struct *group_leader; +}; + +BTF_TYPE_SAFE_RCU(struct cgroup) { + /* cgrp->kn is always accessible as documented in kernel/cgroup/cgroup.c */ + struct kernfs_node *kn; +}; + +BTF_TYPE_SAFE_RCU(struct css_set) { + struct cgroup *dfl_cgrp; +}; + +/* RCU trusted: these fields are trusted in RCU CS and can be NULL */ +BTF_TYPE_SAFE_RCU_OR_NULL(struct mm_struct) { + struct file __rcu *exe_file; +}; + +/* skb->sk, req->sk are not RCU protected, but we mark them as such + * because bpf prog accessible sockets are SOCK_RCU_FREE. + */ +BTF_TYPE_SAFE_RCU_OR_NULL(struct sk_buff) { + struct sock *sk; +}; + +BTF_TYPE_SAFE_RCU_OR_NULL(struct request_sock) { + struct sock *sk; +}; + +/* full trusted: these fields are trusted even outside of RCU CS and never NULL */ +BTF_TYPE_SAFE_TRUSTED(struct bpf_iter_meta) { + struct seq_file *seq; +}; + +BTF_TYPE_SAFE_TRUSTED(struct bpf_iter__task) { + struct bpf_iter_meta *meta; + struct task_struct *task; +}; + +BTF_TYPE_SAFE_TRUSTED(struct linux_binprm) { + struct file *file; +}; + +BTF_TYPE_SAFE_TRUSTED(struct file) { + struct inode *f_inode; +}; + +BTF_TYPE_SAFE_TRUSTED(struct dentry) { + /* no negative dentry-s in places where bpf can see it */ + struct inode *d_inode; +}; + +BTF_TYPE_SAFE_TRUSTED(struct socket) { + struct sock *sk; +}; + +static bool type_is_rcu(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, + const char *field_name, u32 btf_id) +{ + BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct task_struct)); + BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct cgroup)); + BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct css_set)); + + return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_rcu"); +} + +static bool type_is_rcu_or_null(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, + const char *field_name, u32 btf_id) +{ + BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU_OR_NULL(struct mm_struct)); + BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU_OR_NULL(struct sk_buff)); + BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU_OR_NULL(struct request_sock)); + + return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_rcu_or_null"); +} + +static bool type_is_trusted(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, + const char *field_name, u32 btf_id) +{ + BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct bpf_iter_meta)); + BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct bpf_iter__task)); + BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct linux_binprm)); + BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct file)); + BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct dentry)); + BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct socket)); + + return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_trusted"); +} + +static int check_ptr_to_btf_access(struct bpf_verifier_env *env, + struct bpf_reg_state *regs, + int regno, int off, int size, + enum bpf_access_type atype, + int value_regno) +{ + struct bpf_reg_state *reg = regs + regno; + const struct btf_type *t = btf_type_by_id(reg->btf, reg->btf_id); + const char *tname = btf_name_by_offset(reg->btf, t->name_off); + const char *field_name = NULL; + enum bpf_type_flag flag = 0; + u32 btf_id = 0; + int ret; + + if (!env->allow_ptr_leaks) { + verbose(env, + "'struct %s' access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN\n", + tname); + return -EPERM; + } + if (!env->prog->gpl_compatible && btf_is_kernel(reg->btf)) { + verbose(env, + "Cannot access kernel 'struct %s' from non-GPL compatible program\n", + tname); + return -EINVAL; + } + if (off < 0) { + verbose(env, + "R%d is ptr_%s invalid negative access: off=%d\n", + regno, tname, off); + return -EACCES; + } + if (!tnum_is_const(reg->var_off) || reg->var_off.value) { + char tn_buf[48]; + + tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); + verbose(env, + "R%d is ptr_%s invalid variable offset: off=%d, var_off=%s\n", + regno, tname, off, tn_buf); + return -EACCES; + } + + if (reg->type & MEM_USER) { + verbose(env, + "R%d is ptr_%s access user memory: off=%d\n", + regno, tname, off); + return -EACCES; + } + + if (reg->type & MEM_PERCPU) { + verbose(env, + "R%d is ptr_%s access percpu memory: off=%d\n", + regno, tname, off); + return -EACCES; + } + + if (env->ops->btf_struct_access && !type_is_alloc(reg->type) && atype == BPF_WRITE) { + if (!btf_is_kernel(reg->btf)) { + verbose(env, "verifier internal error: reg->btf must be kernel btf\n"); + return -EFAULT; + } + ret = env->ops->btf_struct_access(&env->log, reg, off, size); + } else { + /* Writes are permitted with default btf_struct_access for + * program allocated objects (which always have ref_obj_id > 0), + * but not for untrusted PTR_TO_BTF_ID | MEM_ALLOC. + */ + if (atype != BPF_READ && !type_is_ptr_alloc_obj(reg->type)) { + verbose(env, "only read is supported\n"); + return -EACCES; + } + + if (type_is_alloc(reg->type) && !type_is_non_owning_ref(reg->type) && + !reg->ref_obj_id) { + verbose(env, "verifier internal error: ref_obj_id for allocated object must be non-zero\n"); + return -EFAULT; + } + + ret = btf_struct_access(&env->log, reg, off, size, atype, &btf_id, &flag, &field_name); + } + + if (ret < 0) + return ret; + + if (ret != PTR_TO_BTF_ID) { + /* just mark; */ + + } else if (type_flag(reg->type) & PTR_UNTRUSTED) { + /* If this is an untrusted pointer, all pointers formed by walking it + * also inherit the untrusted flag. + */ + flag = PTR_UNTRUSTED; + + } else if (is_trusted_reg(reg) || is_rcu_reg(reg)) { + /* By default any pointer obtained from walking a trusted pointer is no + * longer trusted, unless the field being accessed has explicitly been + * marked as inheriting its parent's state of trust (either full or RCU). + * For example: + * 'cgroups' pointer is untrusted if task->cgroups dereference + * happened in a sleepable program outside of bpf_rcu_read_lock() + * section. In a non-sleepable program it's trusted while in RCU CS (aka MEM_RCU). + * Note bpf_rcu_read_unlock() converts MEM_RCU pointers to PTR_UNTRUSTED. + * + * A regular RCU-protected pointer with __rcu tag can also be deemed + * trusted if we are in an RCU CS. Such pointer can be NULL. + */ + if (type_is_trusted(env, reg, field_name, btf_id)) { + flag |= PTR_TRUSTED; + } else if (in_rcu_cs(env) && !type_may_be_null(reg->type)) { + if (type_is_rcu(env, reg, field_name, btf_id)) { + /* ignore __rcu tag and mark it MEM_RCU */ + flag |= MEM_RCU; + } else if (flag & MEM_RCU || + type_is_rcu_or_null(env, reg, field_name, btf_id)) { + /* __rcu tagged pointers can be NULL */ + flag |= MEM_RCU | PTR_MAYBE_NULL; + + /* We always trust them */ + if (type_is_rcu_or_null(env, reg, field_name, btf_id) && + flag & PTR_UNTRUSTED) + flag &= ~PTR_UNTRUSTED; + } else if (flag & (MEM_PERCPU | MEM_USER)) { + /* keep as-is */ + } else { + /* walking unknown pointers yields old deprecated PTR_TO_BTF_ID */ + clear_trusted_flags(&flag); + } + } else { + /* + * If not in RCU CS or MEM_RCU pointer can be NULL then + * aggressively mark as untrusted otherwise such + * pointers will be plain PTR_TO_BTF_ID without flags + * and will be allowed to be passed into helpers for + * compat reasons. + */ + flag = PTR_UNTRUSTED; + } + } else { + /* Old compat. Deprecated */ + clear_trusted_flags(&flag); + } + + if (atype == BPF_READ && value_regno >= 0) + mark_btf_ld_reg(env, regs, value_regno, ret, reg->btf, btf_id, flag); + + return 0; +} + +static int check_ptr_to_map_access(struct bpf_verifier_env *env, + struct bpf_reg_state *regs, + int regno, int off, int size, + enum bpf_access_type atype, + int value_regno) +{ + struct bpf_reg_state *reg = regs + regno; + struct bpf_map *map = reg->map_ptr; + struct bpf_reg_state map_reg; + enum bpf_type_flag flag = 0; + const struct btf_type *t; + const char *tname; + u32 btf_id; + int ret; + + if (!btf_vmlinux) { + verbose(env, "map_ptr access not supported without CONFIG_DEBUG_INFO_BTF\n"); + return -ENOTSUPP; + } + + if (!map->ops->map_btf_id || !*map->ops->map_btf_id) { + verbose(env, "map_ptr access not supported for map type %d\n", + map->map_type); + return -ENOTSUPP; + } + + t = btf_type_by_id(btf_vmlinux, *map->ops->map_btf_id); + tname = btf_name_by_offset(btf_vmlinux, t->name_off); + + if (!env->allow_ptr_leaks) { + verbose(env, + "'struct %s' access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN\n", + tname); + return -EPERM; + } + + if (off < 0) { + verbose(env, "R%d is %s invalid negative access: off=%d\n", + regno, tname, off); + return -EACCES; + } + + if (atype != BPF_READ) { + verbose(env, "only read from %s is supported\n", tname); + return -EACCES; + } + + /* Simulate access to a PTR_TO_BTF_ID */ + memset(&map_reg, 0, sizeof(map_reg)); + mark_btf_ld_reg(env, &map_reg, 0, PTR_TO_BTF_ID, btf_vmlinux, *map->ops->map_btf_id, 0); + ret = btf_struct_access(&env->log, &map_reg, off, size, atype, &btf_id, &flag, NULL); + if (ret < 0) + return ret; + + if (value_regno >= 0) + mark_btf_ld_reg(env, regs, value_regno, ret, btf_vmlinux, btf_id, flag); + + return 0; +} + +/* Check that the stack access at the given offset is within bounds. The + * maximum valid offset is -1. + * + * The minimum valid offset is -MAX_BPF_STACK for writes, and + * -state->allocated_stack for reads. + */ +static int check_stack_slot_within_bounds(struct bpf_verifier_env *env, + s64 off, + struct bpf_func_state *state, + enum bpf_access_type t) +{ + int min_valid_off; + + if (t == BPF_WRITE || env->allow_uninit_stack) + min_valid_off = -MAX_BPF_STACK; + else + min_valid_off = -state->allocated_stack; + + if (off < min_valid_off || off > -1) + return -EACCES; + return 0; +} + +/* Check that the stack access at 'regno + off' falls within the maximum stack + * bounds. + * + * 'off' includes `regno->offset`, but not its dynamic part (if any). + */ +static int check_stack_access_within_bounds( + struct bpf_verifier_env *env, + int regno, int off, int access_size, + enum bpf_access_src src, enum bpf_access_type type) +{ + struct bpf_reg_state *regs = cur_regs(env); + struct bpf_reg_state *reg = regs + regno; + struct bpf_func_state *state = func(env, reg); + s64 min_off, max_off; + int err; + char *err_extra; + + if (src == ACCESS_HELPER) + /* We don't know if helpers are reading or writing (or both). */ + err_extra = " indirect access to"; + else if (type == BPF_READ) + err_extra = " read from"; + else + err_extra = " write to"; + + if (tnum_is_const(reg->var_off)) { + min_off = (s64)reg->var_off.value + off; + max_off = min_off + access_size; + } else { + if (reg->smax_value >= BPF_MAX_VAR_OFF || + reg->smin_value <= -BPF_MAX_VAR_OFF) { + verbose(env, "invalid unbounded variable-offset%s stack R%d\n", + err_extra, regno); + return -EACCES; + } + min_off = reg->smin_value + off; + max_off = reg->smax_value + off + access_size; + } + + err = check_stack_slot_within_bounds(env, min_off, state, type); + if (!err && max_off > 0) + err = -EINVAL; /* out of stack access into non-negative offsets */ + + if (err) { + if (tnum_is_const(reg->var_off)) { + verbose(env, "invalid%s stack R%d off=%d size=%d\n", + err_extra, regno, off, access_size); + } else { + char tn_buf[48]; + + tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); + verbose(env, "invalid variable-offset%s stack R%d var_off=%s size=%d\n", + err_extra, regno, tn_buf, access_size); + } + return err; + } + + return grow_stack_state(env, state, round_up(-min_off, BPF_REG_SIZE)); +} + +/* check whether memory at (regno + off) is accessible for t = (read | write) + * if t==write, value_regno is a register which value is stored into memory + * if t==read, value_regno is a register which will receive the value from memory + * if t==write && value_regno==-1, some unknown value is stored into memory + * if t==read && value_regno==-1, don't care what we read from memory + */ +static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regno, + int off, int bpf_size, enum bpf_access_type t, + int value_regno, bool strict_alignment_once, bool is_ldsx) +{ + struct bpf_reg_state *regs = cur_regs(env); + struct bpf_reg_state *reg = regs + regno; + int size, err = 0; + + size = bpf_size_to_bytes(bpf_size); + if (size < 0) + return size; + + /* alignment checks will add in reg->off themselves */ + err = check_ptr_alignment(env, reg, off, size, strict_alignment_once); + if (err) + return err; + + /* for access checks, reg->off is just part of off */ + off += reg->off; + + if (reg->type == PTR_TO_MAP_KEY) { + if (t == BPF_WRITE) { + verbose(env, "write to change key R%d not allowed\n", regno); + return -EACCES; + } + + err = check_mem_region_access(env, regno, off, size, + reg->map_ptr->key_size, false); + if (err) + return err; + if (value_regno >= 0) + mark_reg_unknown(env, regs, value_regno); + } else if (reg->type == PTR_TO_MAP_VALUE) { + struct btf_field *kptr_field = NULL; + + if (t == BPF_WRITE && value_regno >= 0 && + is_pointer_value(env, value_regno)) { + verbose(env, "R%d leaks addr into map\n", value_regno); + return -EACCES; + } + err = check_map_access_type(env, regno, off, size, t); + if (err) + return err; + err = check_map_access(env, regno, off, size, false, ACCESS_DIRECT); + if (err) + return err; + if (tnum_is_const(reg->var_off)) + kptr_field = btf_record_find(reg->map_ptr->record, + off + reg->var_off.value, BPF_KPTR); + if (kptr_field) { + err = check_map_kptr_access(env, regno, value_regno, insn_idx, kptr_field); + } else if (t == BPF_READ && value_regno >= 0) { + struct bpf_map *map = reg->map_ptr; + + /* if map is read-only, track its contents as scalars */ + if (tnum_is_const(reg->var_off) && + bpf_map_is_rdonly(map) && + map->ops->map_direct_value_addr) { + int map_off = off + reg->var_off.value; + u64 val = 0; + + err = bpf_map_direct_read(map, map_off, size, + &val, is_ldsx); + if (err) + return err; + + regs[value_regno].type = SCALAR_VALUE; + __mark_reg_known(®s[value_regno], val); + } else { + mark_reg_unknown(env, regs, value_regno); + } + } + } else if (base_type(reg->type) == PTR_TO_MEM) { + bool rdonly_mem = type_is_rdonly_mem(reg->type); + + if (type_may_be_null(reg->type)) { + verbose(env, "R%d invalid mem access '%s'\n", regno, + reg_type_str(env, reg->type)); + return -EACCES; + } + + if (t == BPF_WRITE && rdonly_mem) { + verbose(env, "R%d cannot write into %s\n", + regno, reg_type_str(env, reg->type)); + return -EACCES; + } + + if (t == BPF_WRITE && value_regno >= 0 && + is_pointer_value(env, value_regno)) { + verbose(env, "R%d leaks addr into mem\n", value_regno); + return -EACCES; + } + + err = check_mem_region_access(env, regno, off, size, + reg->mem_size, false); + if (!err && value_regno >= 0 && (t == BPF_READ || rdonly_mem)) + mark_reg_unknown(env, regs, value_regno); + } else if (reg->type == PTR_TO_CTX) { + enum bpf_reg_type reg_type = SCALAR_VALUE; + struct btf *btf = NULL; + u32 btf_id = 0; + + if (t == BPF_WRITE && value_regno >= 0 && + is_pointer_value(env, value_regno)) { + verbose(env, "R%d leaks addr into ctx\n", value_regno); + return -EACCES; + } + + err = check_ptr_off_reg(env, reg, regno); + if (err < 0) + return err; + + err = check_ctx_access(env, insn_idx, off, size, t, ®_type, &btf, + &btf_id); + if (err) + verbose_linfo(env, insn_idx, "; "); + if (!err && t == BPF_READ && value_regno >= 0) { + /* ctx access returns either a scalar, or a + * PTR_TO_PACKET[_META,_END]. In the latter + * case, we know the offset is zero. + */ + if (reg_type == SCALAR_VALUE) { + mark_reg_unknown(env, regs, value_regno); + } else { + mark_reg_known_zero(env, regs, + value_regno); + if (type_may_be_null(reg_type)) + regs[value_regno].id = ++env->id_gen; + /* A load of ctx field could have different + * actual load size with the one encoded in the + * insn. When the dst is PTR, it is for sure not + * a sub-register. + */ + regs[value_regno].subreg_def = DEF_NOT_SUBREG; + if (base_type(reg_type) == PTR_TO_BTF_ID) { + regs[value_regno].btf = btf; + regs[value_regno].btf_id = btf_id; + } + } + regs[value_regno].type = reg_type; + } + + } else if (reg->type == PTR_TO_STACK) { + /* Basic bounds checks. */ + err = check_stack_access_within_bounds(env, regno, off, size, ACCESS_DIRECT, t); + if (err) + return err; + + if (t == BPF_READ) + err = check_stack_read(env, regno, off, size, + value_regno); + else + err = check_stack_write(env, regno, off, size, + value_regno, insn_idx); + } else if (reg_is_pkt_pointer(reg)) { + if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) { + verbose(env, "cannot write into packet\n"); + return -EACCES; + } + if (t == BPF_WRITE && value_regno >= 0 && + is_pointer_value(env, value_regno)) { + verbose(env, "R%d leaks addr into packet\n", + value_regno); + return -EACCES; + } + err = check_packet_access(env, regno, off, size, false); + if (!err && t == BPF_READ && value_regno >= 0) + mark_reg_unknown(env, regs, value_regno); + } else if (reg->type == PTR_TO_FLOW_KEYS) { + if (t == BPF_WRITE && value_regno >= 0 && + is_pointer_value(env, value_regno)) { + verbose(env, "R%d leaks addr into flow keys\n", + value_regno); + return -EACCES; + } + + err = check_flow_keys_access(env, off, size); + if (!err && t == BPF_READ && value_regno >= 0) + mark_reg_unknown(env, regs, value_regno); + } else if (type_is_sk_pointer(reg->type)) { + if (t == BPF_WRITE) { + verbose(env, "R%d cannot write into %s\n", + regno, reg_type_str(env, reg->type)); + return -EACCES; + } + err = check_sock_access(env, insn_idx, regno, off, size, t); + if (!err && value_regno >= 0) + mark_reg_unknown(env, regs, value_regno); + } else if (reg->type == PTR_TO_TP_BUFFER) { + err = check_tp_buffer_access(env, reg, regno, off, size); + if (!err && t == BPF_READ && value_regno >= 0) + mark_reg_unknown(env, regs, value_regno); + } else if (base_type(reg->type) == PTR_TO_BTF_ID && + !type_may_be_null(reg->type)) { + err = check_ptr_to_btf_access(env, regs, regno, off, size, t, + value_regno); + } else if (reg->type == CONST_PTR_TO_MAP) { + err = check_ptr_to_map_access(env, regs, regno, off, size, t, + value_regno); + } else if (base_type(reg->type) == PTR_TO_BUF) { + bool rdonly_mem = type_is_rdonly_mem(reg->type); + u32 *max_access; + + if (rdonly_mem) { + if (t == BPF_WRITE) { + verbose(env, "R%d cannot write into %s\n", + regno, reg_type_str(env, reg->type)); + return -EACCES; + } + max_access = &env->prog->aux->max_rdonly_access; + } else { + max_access = &env->prog->aux->max_rdwr_access; + } + + err = check_buffer_access(env, reg, regno, off, size, false, + max_access); + + if (!err && value_regno >= 0 && (rdonly_mem || t == BPF_READ)) + mark_reg_unknown(env, regs, value_regno); + } else { + verbose(env, "R%d invalid mem access '%s'\n", regno, + reg_type_str(env, reg->type)); + return -EACCES; + } + + if (!err && size < BPF_REG_SIZE && value_regno >= 0 && t == BPF_READ && + regs[value_regno].type == SCALAR_VALUE) { + if (!is_ldsx) + /* b/h/w load zero-extends, mark upper bits as known 0 */ + coerce_reg_to_size(®s[value_regno], size); + else + coerce_reg_to_size_sx(®s[value_regno], size); + } + return err; +} + +static int check_atomic(struct bpf_verifier_env *env, int insn_idx, struct bpf_insn *insn) +{ + int load_reg; + int err; + + switch (insn->imm) { + case BPF_ADD: + case BPF_ADD | BPF_FETCH: + case BPF_AND: + case BPF_AND | BPF_FETCH: + case BPF_OR: + case BPF_OR | BPF_FETCH: + case BPF_XOR: + case BPF_XOR | BPF_FETCH: + case BPF_XCHG: + case BPF_CMPXCHG: + break; + default: + verbose(env, "BPF_ATOMIC uses invalid atomic opcode %02x\n", insn->imm); + return -EINVAL; + } + + if (BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) { + verbose(env, "invalid atomic operand size\n"); + return -EINVAL; + } + + /* check src1 operand */ + err = check_reg_arg(env, insn->src_reg, SRC_OP); + if (err) + return err; + + /* check src2 operand */ + err = check_reg_arg(env, insn->dst_reg, SRC_OP); + if (err) + return err; + + if (insn->imm == BPF_CMPXCHG) { + /* Check comparison of R0 with memory location */ + const u32 aux_reg = BPF_REG_0; + + err = check_reg_arg(env, aux_reg, SRC_OP); + if (err) + return err; + + if (is_pointer_value(env, aux_reg)) { + verbose(env, "R%d leaks addr into mem\n", aux_reg); + return -EACCES; + } + } + + if (is_pointer_value(env, insn->src_reg)) { + verbose(env, "R%d leaks addr into mem\n", insn->src_reg); + return -EACCES; + } + + if (is_ctx_reg(env, insn->dst_reg) || + is_pkt_reg(env, insn->dst_reg) || + is_flow_key_reg(env, insn->dst_reg) || + is_sk_reg(env, insn->dst_reg)) { + verbose(env, "BPF_ATOMIC stores into R%d %s is not allowed\n", + insn->dst_reg, + reg_type_str(env, reg_state(env, insn->dst_reg)->type)); + return -EACCES; + } + + if (insn->imm & BPF_FETCH) { + if (insn->imm == BPF_CMPXCHG) + load_reg = BPF_REG_0; + else + load_reg = insn->src_reg; + + /* check and record load of old value */ + err = check_reg_arg(env, load_reg, DST_OP); + if (err) + return err; + } else { + /* This instruction accesses a memory location but doesn't + * actually load it into a register. + */ + load_reg = -1; + } + + /* Check whether we can read the memory, with second call for fetch + * case to simulate the register fill. + */ + err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, + BPF_SIZE(insn->code), BPF_READ, -1, true, false); + if (!err && load_reg >= 0) + err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, + BPF_SIZE(insn->code), BPF_READ, load_reg, + true, false); + if (err) + return err; + + /* Check whether we can write into the same memory. */ + err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, + BPF_SIZE(insn->code), BPF_WRITE, -1, true, false); + if (err) + return err; + + return 0; +} + +/* When register 'regno' is used to read the stack (either directly or through + * a helper function) make sure that it's within stack boundary and, depending + * on the access type and privileges, that all elements of the stack are + * initialized. + * + * 'off' includes 'regno->off', but not its dynamic part (if any). + * + * All registers that have been spilled on the stack in the slots within the + * read offsets are marked as read. + */ +static int check_stack_range_initialized( + struct bpf_verifier_env *env, int regno, int off, + int access_size, bool zero_size_allowed, + enum bpf_access_src type, struct bpf_call_arg_meta *meta) +{ + struct bpf_reg_state *reg = reg_state(env, regno); + struct bpf_func_state *state = func(env, reg); + int err, min_off, max_off, i, j, slot, spi; + char *err_extra = type == ACCESS_HELPER ? " indirect" : ""; + enum bpf_access_type bounds_check_type; + /* Some accesses can write anything into the stack, others are + * read-only. + */ + bool clobber = false; + + if (access_size == 0 && !zero_size_allowed) { + verbose(env, "invalid zero-sized read\n"); + return -EACCES; + } + + if (type == ACCESS_HELPER) { + /* The bounds checks for writes are more permissive than for + * reads. However, if raw_mode is not set, we'll do extra + * checks below. + */ + bounds_check_type = BPF_WRITE; + clobber = true; + } else { + bounds_check_type = BPF_READ; + } + err = check_stack_access_within_bounds(env, regno, off, access_size, + type, bounds_check_type); + if (err) + return err; + + + if (tnum_is_const(reg->var_off)) { + min_off = max_off = reg->var_off.value + off; + } else { + /* Variable offset is prohibited for unprivileged mode for + * simplicity since it requires corresponding support in + * Spectre masking for stack ALU. + * See also retrieve_ptr_limit(). + */ + if (!env->bypass_spec_v1) { + char tn_buf[48]; + + tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); + verbose(env, "R%d%s variable offset stack access prohibited for !root, var_off=%s\n", + regno, err_extra, tn_buf); + return -EACCES; + } + /* Only initialized buffer on stack is allowed to be accessed + * with variable offset. With uninitialized buffer it's hard to + * guarantee that whole memory is marked as initialized on + * helper return since specific bounds are unknown what may + * cause uninitialized stack leaking. + */ + if (meta && meta->raw_mode) + meta = NULL; + + min_off = reg->smin_value + off; + max_off = reg->smax_value + off; + } + + if (meta && meta->raw_mode) { + /* Ensure we won't be overwriting dynptrs when simulating byte + * by byte access in check_helper_call using meta.access_size. + * This would be a problem if we have a helper in the future + * which takes: + * + * helper(uninit_mem, len, dynptr) + * + * Now, uninint_mem may overlap with dynptr pointer. Hence, it + * may end up writing to dynptr itself when touching memory from + * arg 1. This can be relaxed on a case by case basis for known + * safe cases, but reject due to the possibilitiy of aliasing by + * default. + */ + for (i = min_off; i < max_off + access_size; i++) { + int stack_off = -i - 1; + + spi = __get_spi(i); + /* raw_mode may write past allocated_stack */ + if (state->allocated_stack <= stack_off) + continue; + if (state->stack[spi].slot_type[stack_off % BPF_REG_SIZE] == STACK_DYNPTR) { + verbose(env, "potential write to dynptr at off=%d disallowed\n", i); + return -EACCES; + } + } + meta->access_size = access_size; + meta->regno = regno; + return 0; + } + + for (i = min_off; i < max_off + access_size; i++) { + u8 *stype; + + slot = -i - 1; + spi = slot / BPF_REG_SIZE; + if (state->allocated_stack <= slot) { + verbose(env, "verifier bug: allocated_stack too small"); + return -EFAULT; + } + + stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE]; + if (*stype == STACK_MISC) + goto mark; + if ((*stype == STACK_ZERO) || + (*stype == STACK_INVALID && env->allow_uninit_stack)) { + if (clobber) { + /* helper can write anything into the stack */ + *stype = STACK_MISC; + } + goto mark; + } + + if (is_spilled_reg(&state->stack[spi]) && + (state->stack[spi].spilled_ptr.type == SCALAR_VALUE || + env->allow_ptr_leaks)) { + if (clobber) { + __mark_reg_unknown(env, &state->stack[spi].spilled_ptr); + for (j = 0; j < BPF_REG_SIZE; j++) + scrub_spilled_slot(&state->stack[spi].slot_type[j]); + } + goto mark; + } + + if (tnum_is_const(reg->var_off)) { + verbose(env, "invalid%s read from stack R%d off %d+%d size %d\n", + err_extra, regno, min_off, i - min_off, access_size); + } else { + char tn_buf[48]; + + tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); + verbose(env, "invalid%s read from stack R%d var_off %s+%d size %d\n", + err_extra, regno, tn_buf, i - min_off, access_size); + } + return -EACCES; +mark: + /* reading any byte out of 8-byte 'spill_slot' will cause + * the whole slot to be marked as 'read' + */ + mark_reg_read(env, &state->stack[spi].spilled_ptr, + state->stack[spi].spilled_ptr.parent, + REG_LIVE_READ64); + /* We do not set REG_LIVE_WRITTEN for stack slot, as we can not + * be sure that whether stack slot is written to or not. Hence, + * we must still conservatively propagate reads upwards even if + * helper may write to the entire memory range. + */ + } + return 0; +} + +static int check_helper_mem_access(struct bpf_verifier_env *env, int regno, + int access_size, bool zero_size_allowed, + struct bpf_call_arg_meta *meta) +{ + struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; + u32 *max_access; + + switch (base_type(reg->type)) { + case PTR_TO_PACKET: + case PTR_TO_PACKET_META: + return check_packet_access(env, regno, reg->off, access_size, + zero_size_allowed); + case PTR_TO_MAP_KEY: + if (meta && meta->raw_mode) { + verbose(env, "R%d cannot write into %s\n", regno, + reg_type_str(env, reg->type)); + return -EACCES; + } + return check_mem_region_access(env, regno, reg->off, access_size, + reg->map_ptr->key_size, false); + case PTR_TO_MAP_VALUE: + if (check_map_access_type(env, regno, reg->off, access_size, + meta && meta->raw_mode ? BPF_WRITE : + BPF_READ)) + return -EACCES; + return check_map_access(env, regno, reg->off, access_size, + zero_size_allowed, ACCESS_HELPER); + case PTR_TO_MEM: + if (type_is_rdonly_mem(reg->type)) { + if (meta && meta->raw_mode) { + verbose(env, "R%d cannot write into %s\n", regno, + reg_type_str(env, reg->type)); + return -EACCES; + } + } + return check_mem_region_access(env, regno, reg->off, + access_size, reg->mem_size, + zero_size_allowed); + case PTR_TO_BUF: + if (type_is_rdonly_mem(reg->type)) { + if (meta && meta->raw_mode) { + verbose(env, "R%d cannot write into %s\n", regno, + reg_type_str(env, reg->type)); + return -EACCES; + } + + max_access = &env->prog->aux->max_rdonly_access; + } else { + max_access = &env->prog->aux->max_rdwr_access; + } + return check_buffer_access(env, reg, regno, reg->off, + access_size, zero_size_allowed, + max_access); + case PTR_TO_STACK: + return check_stack_range_initialized( + env, + regno, reg->off, access_size, + zero_size_allowed, ACCESS_HELPER, meta); + case PTR_TO_BTF_ID: + return check_ptr_to_btf_access(env, regs, regno, reg->off, + access_size, BPF_READ, -1); + case PTR_TO_CTX: + /* in case the function doesn't know how to access the context, + * (because we are in a program of type SYSCALL for example), we + * can not statically check its size. + * Dynamically check it now. + */ + if (!env->ops->convert_ctx_access) { + enum bpf_access_type atype = meta && meta->raw_mode ? BPF_WRITE : BPF_READ; + int offset = access_size - 1; + + /* Allow zero-byte read from PTR_TO_CTX */ + if (access_size == 0) + return zero_size_allowed ? 0 : -EACCES; + + return check_mem_access(env, env->insn_idx, regno, offset, BPF_B, + atype, -1, false, false); + } + + fallthrough; + default: /* scalar_value or invalid ptr */ + /* Allow zero-byte read from NULL, regardless of pointer type */ + if (zero_size_allowed && access_size == 0 && + register_is_null(reg)) + return 0; + + verbose(env, "R%d type=%s ", regno, + reg_type_str(env, reg->type)); + verbose(env, "expected=%s\n", reg_type_str(env, PTR_TO_STACK)); + return -EACCES; + } +} + +static int check_mem_size_reg(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, u32 regno, + bool zero_size_allowed, + struct bpf_call_arg_meta *meta) +{ + int err; + + /* This is used to refine r0 return value bounds for helpers + * that enforce this value as an upper bound on return values. + * See do_refine_retval_range() for helpers that can refine + * the return value. C type of helper is u32 so we pull register + * bound from umax_value however, if negative verifier errors + * out. Only upper bounds can be learned because retval is an + * int type and negative retvals are allowed. + */ + meta->msize_max_value = reg->umax_value; + + /* The register is SCALAR_VALUE; the access check + * happens using its boundaries. + */ + if (!tnum_is_const(reg->var_off)) + /* For unprivileged variable accesses, disable raw + * mode so that the program is required to + * initialize all the memory that the helper could + * just partially fill up. + */ + meta = NULL; + + if (reg->smin_value < 0) { + verbose(env, "R%d min value is negative, either use unsigned or 'var &= const'\n", + regno); + return -EACCES; + } + + if (reg->umin_value == 0) { + err = check_helper_mem_access(env, regno - 1, 0, + zero_size_allowed, + meta); + if (err) + return err; + } + + if (reg->umax_value >= BPF_MAX_VAR_SIZ) { + verbose(env, "R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n", + regno); + return -EACCES; + } + err = check_helper_mem_access(env, regno - 1, + reg->umax_value, + zero_size_allowed, meta); + if (!err) + err = mark_chain_precision(env, regno); + return err; +} + +int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg, + u32 regno, u32 mem_size) +{ + bool may_be_null = type_may_be_null(reg->type); + struct bpf_reg_state saved_reg; + struct bpf_call_arg_meta meta; + int err; + + if (register_is_null(reg)) + return 0; + + memset(&meta, 0, sizeof(meta)); + /* Assuming that the register contains a value check if the memory + * access is safe. Temporarily save and restore the register's state as + * the conversion shouldn't be visible to a caller. + */ + if (may_be_null) { + saved_reg = *reg; + mark_ptr_not_null_reg(reg); + } + + err = check_helper_mem_access(env, regno, mem_size, true, &meta); + /* Check access for BPF_WRITE */ + meta.raw_mode = true; + err = err ?: check_helper_mem_access(env, regno, mem_size, true, &meta); + + if (may_be_null) + *reg = saved_reg; + + return err; +} + +static int check_kfunc_mem_size_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg, + u32 regno) +{ + struct bpf_reg_state *mem_reg = &cur_regs(env)[regno - 1]; + bool may_be_null = type_may_be_null(mem_reg->type); + struct bpf_reg_state saved_reg; + struct bpf_call_arg_meta meta; + int err; + + WARN_ON_ONCE(regno < BPF_REG_2 || regno > BPF_REG_5); + + memset(&meta, 0, sizeof(meta)); + + if (may_be_null) { + saved_reg = *mem_reg; + mark_ptr_not_null_reg(mem_reg); + } + + err = check_mem_size_reg(env, reg, regno, true, &meta); + /* Check access for BPF_WRITE */ + meta.raw_mode = true; + err = err ?: check_mem_size_reg(env, reg, regno, true, &meta); + + if (may_be_null) + *mem_reg = saved_reg; + return err; +} + +/* Implementation details: + * bpf_map_lookup returns PTR_TO_MAP_VALUE_OR_NULL. + * bpf_obj_new returns PTR_TO_BTF_ID | MEM_ALLOC | PTR_MAYBE_NULL. + * Two bpf_map_lookups (even with the same key) will have different reg->id. + * Two separate bpf_obj_new will also have different reg->id. + * For traditional PTR_TO_MAP_VALUE or PTR_TO_BTF_ID | MEM_ALLOC, the verifier + * clears reg->id after value_or_null->value transition, since the verifier only + * cares about the range of access to valid map value pointer and doesn't care + * about actual address of the map element. + * For maps with 'struct bpf_spin_lock' inside map value the verifier keeps + * reg->id > 0 after value_or_null->value transition. By doing so + * two bpf_map_lookups will be considered two different pointers that + * point to different bpf_spin_locks. Likewise for pointers to allocated objects + * returned from bpf_obj_new. + * The verifier allows taking only one bpf_spin_lock at a time to avoid + * dead-locks. + * Since only one bpf_spin_lock is allowed the checks are simpler than + * reg_is_refcounted() logic. The verifier needs to remember only + * one spin_lock instead of array of acquired_refs. + * cur_state->active_lock remembers which map value element or allocated + * object got locked and clears it after bpf_spin_unlock. + */ +static int process_spin_lock(struct bpf_verifier_env *env, int regno, + bool is_lock) +{ + struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; + struct bpf_verifier_state *cur = env->cur_state; + bool is_const = tnum_is_const(reg->var_off); + u64 val = reg->var_off.value; + struct bpf_map *map = NULL; + struct btf *btf = NULL; + struct btf_record *rec; + + if (!is_const) { + verbose(env, + "R%d doesn't have constant offset. bpf_spin_lock has to be at the constant offset\n", + regno); + return -EINVAL; + } + if (reg->type == PTR_TO_MAP_VALUE) { + map = reg->map_ptr; + if (!map->btf) { + verbose(env, + "map '%s' has to have BTF in order to use bpf_spin_lock\n", + map->name); + return -EINVAL; + } + } else { + btf = reg->btf; + } + + rec = reg_btf_record(reg); + if (!btf_record_has_field(rec, BPF_SPIN_LOCK)) { + verbose(env, "%s '%s' has no valid bpf_spin_lock\n", map ? "map" : "local", + map ? map->name : "kptr"); + return -EINVAL; + } + if (rec->spin_lock_off != val + reg->off) { + verbose(env, "off %lld doesn't point to 'struct bpf_spin_lock' that is at %d\n", + val + reg->off, rec->spin_lock_off); + return -EINVAL; + } + if (is_lock) { + if (cur->active_lock.ptr) { + verbose(env, + "Locking two bpf_spin_locks are not allowed\n"); + return -EINVAL; + } + if (map) + cur->active_lock.ptr = map; + else + cur->active_lock.ptr = btf; + cur->active_lock.id = reg->id; + } else { + void *ptr; + + if (map) + ptr = map; + else + ptr = btf; + + if (!cur->active_lock.ptr) { + verbose(env, "bpf_spin_unlock without taking a lock\n"); + return -EINVAL; + } + if (cur->active_lock.ptr != ptr || + cur->active_lock.id != reg->id) { + verbose(env, "bpf_spin_unlock of different lock\n"); + return -EINVAL; + } + + invalidate_non_owning_refs(env); + + cur->active_lock.ptr = NULL; + cur->active_lock.id = 0; + } + return 0; +} + +static int process_timer_func(struct bpf_verifier_env *env, int regno, + struct bpf_call_arg_meta *meta) +{ + struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; + bool is_const = tnum_is_const(reg->var_off); + struct bpf_map *map = reg->map_ptr; + u64 val = reg->var_off.value; + + if (!is_const) { + verbose(env, + "R%d doesn't have constant offset. bpf_timer has to be at the constant offset\n", + regno); + return -EINVAL; + } + if (!map->btf) { + verbose(env, "map '%s' has to have BTF in order to use bpf_timer\n", + map->name); + return -EINVAL; + } + if (!btf_record_has_field(map->record, BPF_TIMER)) { + verbose(env, "map '%s' has no valid bpf_timer\n", map->name); + return -EINVAL; + } + if (map->record->timer_off != val + reg->off) { + verbose(env, "off %lld doesn't point to 'struct bpf_timer' that is at %d\n", + val + reg->off, map->record->timer_off); + return -EINVAL; + } + if (meta->map_ptr) { + verbose(env, "verifier bug. Two map pointers in a timer helper\n"); + return -EFAULT; + } + meta->map_uid = reg->map_uid; + meta->map_ptr = map; + return 0; +} + +static int process_kptr_func(struct bpf_verifier_env *env, int regno, + struct bpf_call_arg_meta *meta) +{ + struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; + struct bpf_map *map_ptr = reg->map_ptr; + struct btf_field *kptr_field; + u32 kptr_off; + + if (!tnum_is_const(reg->var_off)) { + verbose(env, + "R%d doesn't have constant offset. kptr has to be at the constant offset\n", + regno); + return -EINVAL; + } + if (!map_ptr->btf) { + verbose(env, "map '%s' has to have BTF in order to use bpf_kptr_xchg\n", + map_ptr->name); + return -EINVAL; + } + if (!btf_record_has_field(map_ptr->record, BPF_KPTR)) { + verbose(env, "map '%s' has no valid kptr\n", map_ptr->name); + return -EINVAL; + } + + meta->map_ptr = map_ptr; + kptr_off = reg->off + reg->var_off.value; + kptr_field = btf_record_find(map_ptr->record, kptr_off, BPF_KPTR); + if (!kptr_field) { + verbose(env, "off=%d doesn't point to kptr\n", kptr_off); + return -EACCES; + } + if (kptr_field->type != BPF_KPTR_REF) { + verbose(env, "off=%d kptr isn't referenced kptr\n", kptr_off); + return -EACCES; + } + meta->kptr_field = kptr_field; + return 0; +} + +/* There are two register types representing a bpf_dynptr, one is PTR_TO_STACK + * which points to a stack slot, and the other is CONST_PTR_TO_DYNPTR. + * + * In both cases we deal with the first 8 bytes, but need to mark the next 8 + * bytes as STACK_DYNPTR in case of PTR_TO_STACK. In case of + * CONST_PTR_TO_DYNPTR, we are guaranteed to get the beginning of the object. + * + * Mutability of bpf_dynptr is at two levels, one is at the level of struct + * bpf_dynptr itself, i.e. whether the helper is receiving a pointer to struct + * bpf_dynptr or pointer to const struct bpf_dynptr. In the former case, it can + * mutate the view of the dynptr and also possibly destroy it. In the latter + * case, it cannot mutate the bpf_dynptr itself but it can still mutate the + * memory that dynptr points to. + * + * The verifier will keep track both levels of mutation (bpf_dynptr's in + * reg->type and the memory's in reg->dynptr.type), but there is no support for + * readonly dynptr view yet, hence only the first case is tracked and checked. + * + * This is consistent with how C applies the const modifier to a struct object, + * where the pointer itself inside bpf_dynptr becomes const but not what it + * points to. + * + * Helpers which do not mutate the bpf_dynptr set MEM_RDONLY in their argument + * type, and declare it as 'const struct bpf_dynptr *' in their prototype. + */ +static int process_dynptr_func(struct bpf_verifier_env *env, int regno, int insn_idx, + enum bpf_arg_type arg_type, int clone_ref_obj_id) +{ + struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; + int err; + + /* MEM_UNINIT and MEM_RDONLY are exclusive, when applied to an + * ARG_PTR_TO_DYNPTR (or ARG_PTR_TO_DYNPTR | DYNPTR_TYPE_*): + */ + if ((arg_type & (MEM_UNINIT | MEM_RDONLY)) == (MEM_UNINIT | MEM_RDONLY)) { + verbose(env, "verifier internal error: misconfigured dynptr helper type flags\n"); + return -EFAULT; + } + + /* MEM_UNINIT - Points to memory that is an appropriate candidate for + * constructing a mutable bpf_dynptr object. + * + * Currently, this is only possible with PTR_TO_STACK + * pointing to a region of at least 16 bytes which doesn't + * contain an existing bpf_dynptr. + * + * MEM_RDONLY - Points to a initialized bpf_dynptr that will not be + * mutated or destroyed. However, the memory it points to + * may be mutated. + * + * None - Points to a initialized dynptr that can be mutated and + * destroyed, including mutation of the memory it points + * to. + */ + if (arg_type & MEM_UNINIT) { + int i; + + if (!is_dynptr_reg_valid_uninit(env, reg)) { + verbose(env, "Dynptr has to be an uninitialized dynptr\n"); + return -EINVAL; + } + + /* we write BPF_DW bits (8 bytes) at a time */ + for (i = 0; i < BPF_DYNPTR_SIZE; i += 8) { + err = check_mem_access(env, insn_idx, regno, + i, BPF_DW, BPF_WRITE, -1, false, false); + if (err) + return err; + } + + err = mark_stack_slots_dynptr(env, reg, arg_type, insn_idx, clone_ref_obj_id); + } else /* MEM_RDONLY and None case from above */ { + /* For the reg->type == PTR_TO_STACK case, bpf_dynptr is never const */ + if (reg->type == CONST_PTR_TO_DYNPTR && !(arg_type & MEM_RDONLY)) { + verbose(env, "cannot pass pointer to const bpf_dynptr, the helper mutates it\n"); + return -EINVAL; + } + + if (!is_dynptr_reg_valid_init(env, reg)) { + verbose(env, + "Expected an initialized dynptr as arg #%d\n", + regno); + return -EINVAL; + } + + /* Fold modifiers (in this case, MEM_RDONLY) when checking expected type */ + if (!is_dynptr_type_expected(env, reg, arg_type & ~MEM_RDONLY)) { + verbose(env, + "Expected a dynptr of type %s as arg #%d\n", + dynptr_type_str(arg_to_dynptr_type(arg_type)), regno); + return -EINVAL; + } + + err = mark_dynptr_read(env, reg); + } + return err; +} + +static u32 iter_ref_obj_id(struct bpf_verifier_env *env, struct bpf_reg_state *reg, int spi) +{ + struct bpf_func_state *state = func(env, reg); + + return state->stack[spi].spilled_ptr.ref_obj_id; +} + +static bool is_iter_kfunc(struct bpf_kfunc_call_arg_meta *meta) +{ + return meta->kfunc_flags & (KF_ITER_NEW | KF_ITER_NEXT | KF_ITER_DESTROY); +} + +static bool is_iter_new_kfunc(struct bpf_kfunc_call_arg_meta *meta) +{ + return meta->kfunc_flags & KF_ITER_NEW; +} + +static bool is_iter_next_kfunc(struct bpf_kfunc_call_arg_meta *meta) +{ + return meta->kfunc_flags & KF_ITER_NEXT; +} + +static bool is_iter_destroy_kfunc(struct bpf_kfunc_call_arg_meta *meta) +{ + return meta->kfunc_flags & KF_ITER_DESTROY; +} + +static bool is_kfunc_arg_iter(struct bpf_kfunc_call_arg_meta *meta, int arg) +{ + /* btf_check_iter_kfuncs() guarantees that first argument of any iter + * kfunc is iter state pointer + */ + return arg == 0 && is_iter_kfunc(meta); +} + +static int process_iter_arg(struct bpf_verifier_env *env, int regno, int insn_idx, + struct bpf_kfunc_call_arg_meta *meta) +{ + struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; + const struct btf_type *t; + const struct btf_param *arg; + int spi, err, i, nr_slots; + u32 btf_id; + + /* btf_check_iter_kfuncs() ensures we don't need to validate anything here */ + arg = &btf_params(meta->func_proto)[0]; + t = btf_type_skip_modifiers(meta->btf, arg->type, NULL); /* PTR */ + t = btf_type_skip_modifiers(meta->btf, t->type, &btf_id); /* STRUCT */ + nr_slots = t->size / BPF_REG_SIZE; + + if (is_iter_new_kfunc(meta)) { + /* bpf_iter_<type>_new() expects pointer to uninit iter state */ + if (!is_iter_reg_valid_uninit(env, reg, nr_slots)) { + verbose(env, "expected uninitialized iter_%s as arg #%d\n", + iter_type_str(meta->btf, btf_id), regno); + return -EINVAL; + } + + for (i = 0; i < nr_slots * 8; i += BPF_REG_SIZE) { + err = check_mem_access(env, insn_idx, regno, + i, BPF_DW, BPF_WRITE, -1, false, false); + if (err) + return err; + } + + err = mark_stack_slots_iter(env, reg, insn_idx, meta->btf, btf_id, nr_slots); + if (err) + return err; + } else { + /* iter_next() or iter_destroy() expect initialized iter state*/ + if (!is_iter_reg_valid_init(env, reg, meta->btf, btf_id, nr_slots)) { + verbose(env, "expected an initialized iter_%s as arg #%d\n", + iter_type_str(meta->btf, btf_id), regno); + return -EINVAL; + } + + spi = iter_get_spi(env, reg, nr_slots); + if (spi < 0) + return spi; + + err = mark_iter_read(env, reg, spi, nr_slots); + if (err) + return err; + + /* remember meta->iter info for process_iter_next_call() */ + meta->iter.spi = spi; + meta->iter.frameno = reg->frameno; + meta->ref_obj_id = iter_ref_obj_id(env, reg, spi); + + if (is_iter_destroy_kfunc(meta)) { + err = unmark_stack_slots_iter(env, reg, nr_slots); + if (err) + return err; + } + } + + return 0; +} + +/* Look for a previous loop entry at insn_idx: nearest parent state + * stopped at insn_idx with callsites matching those in cur->frame. + */ +static struct bpf_verifier_state *find_prev_entry(struct bpf_verifier_env *env, + struct bpf_verifier_state *cur, + int insn_idx) +{ + struct bpf_verifier_state_list *sl; + struct bpf_verifier_state *st; + + /* Explored states are pushed in stack order, most recent states come first */ + sl = *explored_state(env, insn_idx); + for (; sl; sl = sl->next) { + /* If st->branches != 0 state is a part of current DFS verification path, + * hence cur & st for a loop. + */ + st = &sl->state; + if (st->insn_idx == insn_idx && st->branches && same_callsites(st, cur) && + st->dfs_depth < cur->dfs_depth) + return st; + } + + return NULL; +} + +static void reset_idmap_scratch(struct bpf_verifier_env *env); +static bool regs_exact(const struct bpf_reg_state *rold, + const struct bpf_reg_state *rcur, + struct bpf_idmap *idmap); + +static void maybe_widen_reg(struct bpf_verifier_env *env, + struct bpf_reg_state *rold, struct bpf_reg_state *rcur, + struct bpf_idmap *idmap) +{ + if (rold->type != SCALAR_VALUE) + return; + if (rold->type != rcur->type) + return; + if (rold->precise || rcur->precise || regs_exact(rold, rcur, idmap)) + return; + __mark_reg_unknown(env, rcur); +} + +static int widen_imprecise_scalars(struct bpf_verifier_env *env, + struct bpf_verifier_state *old, + struct bpf_verifier_state *cur) +{ + struct bpf_func_state *fold, *fcur; + int i, fr; + + reset_idmap_scratch(env); + for (fr = old->curframe; fr >= 0; fr--) { + fold = old->frame[fr]; + fcur = cur->frame[fr]; + + for (i = 0; i < MAX_BPF_REG; i++) + maybe_widen_reg(env, + &fold->regs[i], + &fcur->regs[i], + &env->idmap_scratch); + + for (i = 0; i < fold->allocated_stack / BPF_REG_SIZE; i++) { + if (!is_spilled_reg(&fold->stack[i]) || + !is_spilled_reg(&fcur->stack[i])) + continue; + + maybe_widen_reg(env, + &fold->stack[i].spilled_ptr, + &fcur->stack[i].spilled_ptr, + &env->idmap_scratch); + } + } + return 0; +} + +/* process_iter_next_call() is called when verifier gets to iterator's next + * "method" (e.g., bpf_iter_num_next() for numbers iterator) call. We'll refer + * to it as just "iter_next()" in comments below. + * + * BPF verifier relies on a crucial contract for any iter_next() + * implementation: it should *eventually* return NULL, and once that happens + * it should keep returning NULL. That is, once iterator exhausts elements to + * iterate, it should never reset or spuriously return new elements. + * + * With the assumption of such contract, process_iter_next_call() simulates + * a fork in the verifier state to validate loop logic correctness and safety + * without having to simulate infinite amount of iterations. + * + * In current state, we first assume that iter_next() returned NULL and + * iterator state is set to DRAINED (BPF_ITER_STATE_DRAINED). In such + * conditions we should not form an infinite loop and should eventually reach + * exit. + * + * Besides that, we also fork current state and enqueue it for later + * verification. In a forked state we keep iterator state as ACTIVE + * (BPF_ITER_STATE_ACTIVE) and assume non-NULL return from iter_next(). We + * also bump iteration depth to prevent erroneous infinite loop detection + * later on (see iter_active_depths_differ() comment for details). In this + * state we assume that we'll eventually loop back to another iter_next() + * calls (it could be in exactly same location or in some other instruction, + * it doesn't matter, we don't make any unnecessary assumptions about this, + * everything revolves around iterator state in a stack slot, not which + * instruction is calling iter_next()). When that happens, we either will come + * to iter_next() with equivalent state and can conclude that next iteration + * will proceed in exactly the same way as we just verified, so it's safe to + * assume that loop converges. If not, we'll go on another iteration + * simulation with a different input state, until all possible starting states + * are validated or we reach maximum number of instructions limit. + * + * This way, we will either exhaustively discover all possible input states + * that iterator loop can start with and eventually will converge, or we'll + * effectively regress into bounded loop simulation logic and either reach + * maximum number of instructions if loop is not provably convergent, or there + * is some statically known limit on number of iterations (e.g., if there is + * an explicit `if n > 100 then break;` statement somewhere in the loop). + * + * Iteration convergence logic in is_state_visited() relies on exact + * states comparison, which ignores read and precision marks. + * This is necessary because read and precision marks are not finalized + * while in the loop. Exact comparison might preclude convergence for + * simple programs like below: + * + * i = 0; + * while(iter_next(&it)) + * i++; + * + * At each iteration step i++ would produce a new distinct state and + * eventually instruction processing limit would be reached. + * + * To avoid such behavior speculatively forget (widen) range for + * imprecise scalar registers, if those registers were not precise at the + * end of the previous iteration and do not match exactly. + * + * This is a conservative heuristic that allows to verify wide range of programs, + * however it precludes verification of programs that conjure an + * imprecise value on the first loop iteration and use it as precise on a second. + * For example, the following safe program would fail to verify: + * + * struct bpf_num_iter it; + * int arr[10]; + * int i = 0, a = 0; + * bpf_iter_num_new(&it, 0, 10); + * while (bpf_iter_num_next(&it)) { + * if (a == 0) { + * a = 1; + * i = 7; // Because i changed verifier would forget + * // it's range on second loop entry. + * } else { + * arr[i] = 42; // This would fail to verify. + * } + * } + * bpf_iter_num_destroy(&it); + */ +static int process_iter_next_call(struct bpf_verifier_env *env, int insn_idx, + struct bpf_kfunc_call_arg_meta *meta) +{ + struct bpf_verifier_state *cur_st = env->cur_state, *queued_st, *prev_st; + struct bpf_func_state *cur_fr = cur_st->frame[cur_st->curframe], *queued_fr; + struct bpf_reg_state *cur_iter, *queued_iter; + int iter_frameno = meta->iter.frameno; + int iter_spi = meta->iter.spi; + + BTF_TYPE_EMIT(struct bpf_iter); + + cur_iter = &env->cur_state->frame[iter_frameno]->stack[iter_spi].spilled_ptr; + + if (cur_iter->iter.state != BPF_ITER_STATE_ACTIVE && + cur_iter->iter.state != BPF_ITER_STATE_DRAINED) { + verbose(env, "verifier internal error: unexpected iterator state %d (%s)\n", + cur_iter->iter.state, iter_state_str(cur_iter->iter.state)); + return -EFAULT; + } + + if (cur_iter->iter.state == BPF_ITER_STATE_ACTIVE) { + /* Because iter_next() call is a checkpoint is_state_visitied() + * should guarantee parent state with same call sites and insn_idx. + */ + if (!cur_st->parent || cur_st->parent->insn_idx != insn_idx || + !same_callsites(cur_st->parent, cur_st)) { + verbose(env, "bug: bad parent state for iter next call"); + return -EFAULT; + } + /* Note cur_st->parent in the call below, it is necessary to skip + * checkpoint created for cur_st by is_state_visited() + * right at this instruction. + */ + prev_st = find_prev_entry(env, cur_st->parent, insn_idx); + /* branch out active iter state */ + queued_st = push_stack(env, insn_idx + 1, insn_idx, false); + if (!queued_st) + return -ENOMEM; + + queued_iter = &queued_st->frame[iter_frameno]->stack[iter_spi].spilled_ptr; + queued_iter->iter.state = BPF_ITER_STATE_ACTIVE; + queued_iter->iter.depth++; + if (prev_st) + widen_imprecise_scalars(env, prev_st, queued_st); + + queued_fr = queued_st->frame[queued_st->curframe]; + mark_ptr_not_null_reg(&queued_fr->regs[BPF_REG_0]); + } + + /* switch to DRAINED state, but keep the depth unchanged */ + /* mark current iter state as drained and assume returned NULL */ + cur_iter->iter.state = BPF_ITER_STATE_DRAINED; + __mark_reg_const_zero(&cur_fr->regs[BPF_REG_0]); + + return 0; +} + +static bool arg_type_is_mem_size(enum bpf_arg_type type) +{ + return type == ARG_CONST_SIZE || + type == ARG_CONST_SIZE_OR_ZERO; +} + +static bool arg_type_is_release(enum bpf_arg_type type) +{ + return type & OBJ_RELEASE; +} + +static bool arg_type_is_dynptr(enum bpf_arg_type type) +{ + return base_type(type) == ARG_PTR_TO_DYNPTR; +} + +static int int_ptr_type_to_size(enum bpf_arg_type type) +{ + if (type == ARG_PTR_TO_INT) + return sizeof(u32); + else if (type == ARG_PTR_TO_LONG) + return sizeof(u64); + + return -EINVAL; +} + +static int resolve_map_arg_type(struct bpf_verifier_env *env, + const struct bpf_call_arg_meta *meta, + enum bpf_arg_type *arg_type) +{ + if (!meta->map_ptr) { + /* kernel subsystem misconfigured verifier */ + verbose(env, "invalid map_ptr to access map->type\n"); + return -EACCES; + } + + switch (meta->map_ptr->map_type) { + case BPF_MAP_TYPE_SOCKMAP: + case BPF_MAP_TYPE_SOCKHASH: + if (*arg_type == ARG_PTR_TO_MAP_VALUE) { + *arg_type = ARG_PTR_TO_BTF_ID_SOCK_COMMON; + } else { + verbose(env, "invalid arg_type for sockmap/sockhash\n"); + return -EINVAL; + } + break; + case BPF_MAP_TYPE_BLOOM_FILTER: + if (meta->func_id == BPF_FUNC_map_peek_elem) + *arg_type = ARG_PTR_TO_MAP_VALUE; + break; + default: + break; + } + return 0; +} + +struct bpf_reg_types { + const enum bpf_reg_type types[10]; + u32 *btf_id; +}; + +static const struct bpf_reg_types sock_types = { + .types = { + PTR_TO_SOCK_COMMON, + PTR_TO_SOCKET, + PTR_TO_TCP_SOCK, + PTR_TO_XDP_SOCK, + }, +}; + +#ifdef CONFIG_NET +static const struct bpf_reg_types btf_id_sock_common_types = { + .types = { + PTR_TO_SOCK_COMMON, + PTR_TO_SOCKET, + PTR_TO_TCP_SOCK, + PTR_TO_XDP_SOCK, + PTR_TO_BTF_ID, + PTR_TO_BTF_ID | PTR_TRUSTED, + }, + .btf_id = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON], +}; +#endif + +static const struct bpf_reg_types mem_types = { + .types = { + PTR_TO_STACK, + PTR_TO_PACKET, + PTR_TO_PACKET_META, + PTR_TO_MAP_KEY, + PTR_TO_MAP_VALUE, + PTR_TO_MEM, + PTR_TO_MEM | MEM_RINGBUF, + PTR_TO_BUF, + PTR_TO_BTF_ID | PTR_TRUSTED, + }, +}; + +static const struct bpf_reg_types int_ptr_types = { + .types = { + PTR_TO_STACK, + PTR_TO_PACKET, + PTR_TO_PACKET_META, + PTR_TO_MAP_KEY, + PTR_TO_MAP_VALUE, + }, +}; + +static const struct bpf_reg_types spin_lock_types = { + .types = { + PTR_TO_MAP_VALUE, + PTR_TO_BTF_ID | MEM_ALLOC, + } +}; + +static const struct bpf_reg_types fullsock_types = { .types = { PTR_TO_SOCKET } }; +static const struct bpf_reg_types scalar_types = { .types = { SCALAR_VALUE } }; +static const struct bpf_reg_types context_types = { .types = { PTR_TO_CTX } }; +static const struct bpf_reg_types ringbuf_mem_types = { .types = { PTR_TO_MEM | MEM_RINGBUF } }; +static const struct bpf_reg_types const_map_ptr_types = { .types = { CONST_PTR_TO_MAP } }; +static const struct bpf_reg_types btf_ptr_types = { + .types = { + PTR_TO_BTF_ID, + PTR_TO_BTF_ID | PTR_TRUSTED, + PTR_TO_BTF_ID | MEM_RCU, + }, +}; +static const struct bpf_reg_types percpu_btf_ptr_types = { + .types = { + PTR_TO_BTF_ID | MEM_PERCPU, + PTR_TO_BTF_ID | MEM_PERCPU | PTR_TRUSTED, + } +}; +static const struct bpf_reg_types func_ptr_types = { .types = { PTR_TO_FUNC } }; +static const struct bpf_reg_types stack_ptr_types = { .types = { PTR_TO_STACK } }; +static const struct bpf_reg_types const_str_ptr_types = { .types = { PTR_TO_MAP_VALUE } }; +static const struct bpf_reg_types timer_types = { .types = { PTR_TO_MAP_VALUE } }; +static const struct bpf_reg_types kptr_types = { .types = { PTR_TO_MAP_VALUE } }; +static const struct bpf_reg_types dynptr_types = { + .types = { + PTR_TO_STACK, + CONST_PTR_TO_DYNPTR, + } +}; + +static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = { + [ARG_PTR_TO_MAP_KEY] = &mem_types, + [ARG_PTR_TO_MAP_VALUE] = &mem_types, + [ARG_CONST_SIZE] = &scalar_types, + [ARG_CONST_SIZE_OR_ZERO] = &scalar_types, + [ARG_CONST_ALLOC_SIZE_OR_ZERO] = &scalar_types, + [ARG_CONST_MAP_PTR] = &const_map_ptr_types, + [ARG_PTR_TO_CTX] = &context_types, + [ARG_PTR_TO_SOCK_COMMON] = &sock_types, +#ifdef CONFIG_NET + [ARG_PTR_TO_BTF_ID_SOCK_COMMON] = &btf_id_sock_common_types, +#endif + [ARG_PTR_TO_SOCKET] = &fullsock_types, + [ARG_PTR_TO_BTF_ID] = &btf_ptr_types, + [ARG_PTR_TO_SPIN_LOCK] = &spin_lock_types, + [ARG_PTR_TO_MEM] = &mem_types, + [ARG_PTR_TO_RINGBUF_MEM] = &ringbuf_mem_types, + [ARG_PTR_TO_INT] = &int_ptr_types, + [ARG_PTR_TO_LONG] = &int_ptr_types, + [ARG_PTR_TO_PERCPU_BTF_ID] = &percpu_btf_ptr_types, + [ARG_PTR_TO_FUNC] = &func_ptr_types, + [ARG_PTR_TO_STACK] = &stack_ptr_types, + [ARG_PTR_TO_CONST_STR] = &const_str_ptr_types, + [ARG_PTR_TO_TIMER] = &timer_types, + [ARG_PTR_TO_KPTR] = &kptr_types, + [ARG_PTR_TO_DYNPTR] = &dynptr_types, +}; + +static int check_reg_type(struct bpf_verifier_env *env, u32 regno, + enum bpf_arg_type arg_type, + const u32 *arg_btf_id, + struct bpf_call_arg_meta *meta) +{ + struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; + enum bpf_reg_type expected, type = reg->type; + const struct bpf_reg_types *compatible; + int i, j; + + compatible = compatible_reg_types[base_type(arg_type)]; + if (!compatible) { + verbose(env, "verifier internal error: unsupported arg type %d\n", arg_type); + return -EFAULT; + } + + /* ARG_PTR_TO_MEM + RDONLY is compatible with PTR_TO_MEM and PTR_TO_MEM + RDONLY, + * but ARG_PTR_TO_MEM is compatible only with PTR_TO_MEM and NOT with PTR_TO_MEM + RDONLY + * + * Same for MAYBE_NULL: + * + * ARG_PTR_TO_MEM + MAYBE_NULL is compatible with PTR_TO_MEM and PTR_TO_MEM + MAYBE_NULL, + * but ARG_PTR_TO_MEM is compatible only with PTR_TO_MEM but NOT with PTR_TO_MEM + MAYBE_NULL + * + * ARG_PTR_TO_MEM is compatible with PTR_TO_MEM that is tagged with a dynptr type. + * + * Therefore we fold these flags depending on the arg_type before comparison. + */ + if (arg_type & MEM_RDONLY) + type &= ~MEM_RDONLY; + if (arg_type & PTR_MAYBE_NULL) + type &= ~PTR_MAYBE_NULL; + if (base_type(arg_type) == ARG_PTR_TO_MEM) + type &= ~DYNPTR_TYPE_FLAG_MASK; + + if (meta->func_id == BPF_FUNC_kptr_xchg && type_is_alloc(type)) + type &= ~MEM_ALLOC; + + for (i = 0; i < ARRAY_SIZE(compatible->types); i++) { + expected = compatible->types[i]; + if (expected == NOT_INIT) + break; + + if (type == expected) + goto found; + } + + verbose(env, "R%d type=%s expected=", regno, reg_type_str(env, reg->type)); + for (j = 0; j + 1 < i; j++) + verbose(env, "%s, ", reg_type_str(env, compatible->types[j])); + verbose(env, "%s\n", reg_type_str(env, compatible->types[j])); + return -EACCES; + +found: + if (base_type(reg->type) != PTR_TO_BTF_ID) + return 0; + + if (compatible == &mem_types) { + if (!(arg_type & MEM_RDONLY)) { + verbose(env, + "%s() may write into memory pointed by R%d type=%s\n", + func_id_name(meta->func_id), + regno, reg_type_str(env, reg->type)); + return -EACCES; + } + return 0; + } + + switch ((int)reg->type) { + case PTR_TO_BTF_ID: + case PTR_TO_BTF_ID | PTR_TRUSTED: + case PTR_TO_BTF_ID | MEM_RCU: + case PTR_TO_BTF_ID | PTR_MAYBE_NULL: + case PTR_TO_BTF_ID | PTR_MAYBE_NULL | MEM_RCU: + { + /* For bpf_sk_release, it needs to match against first member + * 'struct sock_common', hence make an exception for it. This + * allows bpf_sk_release to work for multiple socket types. + */ + bool strict_type_match = arg_type_is_release(arg_type) && + meta->func_id != BPF_FUNC_sk_release; + + if (type_may_be_null(reg->type) && + (!type_may_be_null(arg_type) || arg_type_is_release(arg_type))) { + verbose(env, "Possibly NULL pointer passed to helper arg%d\n", regno); + return -EACCES; + } + + if (!arg_btf_id) { + if (!compatible->btf_id) { + verbose(env, "verifier internal error: missing arg compatible BTF ID\n"); + return -EFAULT; + } + arg_btf_id = compatible->btf_id; + } + + if (meta->func_id == BPF_FUNC_kptr_xchg) { + if (map_kptr_match_type(env, meta->kptr_field, reg, regno)) + return -EACCES; + } else { + if (arg_btf_id == BPF_PTR_POISON) { + verbose(env, "verifier internal error:"); + verbose(env, "R%d has non-overwritten BPF_PTR_POISON type\n", + regno); + return -EACCES; + } + + if (!btf_struct_ids_match(&env->log, reg->btf, reg->btf_id, reg->off, + btf_vmlinux, *arg_btf_id, + strict_type_match)) { + verbose(env, "R%d is of type %s but %s is expected\n", + regno, btf_type_name(reg->btf, reg->btf_id), + btf_type_name(btf_vmlinux, *arg_btf_id)); + return -EACCES; + } + } + break; + } + case PTR_TO_BTF_ID | MEM_ALLOC: + if (meta->func_id != BPF_FUNC_spin_lock && meta->func_id != BPF_FUNC_spin_unlock && + meta->func_id != BPF_FUNC_kptr_xchg) { + verbose(env, "verifier internal error: unimplemented handling of MEM_ALLOC\n"); + return -EFAULT; + } + if (meta->func_id == BPF_FUNC_kptr_xchg) { + if (map_kptr_match_type(env, meta->kptr_field, reg, regno)) + return -EACCES; + } + break; + case PTR_TO_BTF_ID | MEM_PERCPU: + case PTR_TO_BTF_ID | MEM_PERCPU | PTR_TRUSTED: + /* Handled by helper specific checks */ + break; + default: + verbose(env, "verifier internal error: invalid PTR_TO_BTF_ID register for type match\n"); + return -EFAULT; + } + return 0; +} + +static struct btf_field * +reg_find_field_offset(const struct bpf_reg_state *reg, s32 off, u32 fields) +{ + struct btf_field *field; + struct btf_record *rec; + + rec = reg_btf_record(reg); + if (!rec) + return NULL; + + field = btf_record_find(rec, off, fields); + if (!field) + return NULL; + + return field; +} + +int check_func_arg_reg_off(struct bpf_verifier_env *env, + const struct bpf_reg_state *reg, int regno, + enum bpf_arg_type arg_type) +{ + u32 type = reg->type; + + /* When referenced register is passed to release function, its fixed + * offset must be 0. + * + * We will check arg_type_is_release reg has ref_obj_id when storing + * meta->release_regno. + */ + if (arg_type_is_release(arg_type)) { + /* ARG_PTR_TO_DYNPTR with OBJ_RELEASE is a bit special, as it + * may not directly point to the object being released, but to + * dynptr pointing to such object, which might be at some offset + * on the stack. In that case, we simply to fallback to the + * default handling. + */ + if (arg_type_is_dynptr(arg_type) && type == PTR_TO_STACK) + return 0; + + /* Doing check_ptr_off_reg check for the offset will catch this + * because fixed_off_ok is false, but checking here allows us + * to give the user a better error message. + */ + if (reg->off) { + verbose(env, "R%d must have zero offset when passed to release func or trusted arg to kfunc\n", + regno); + return -EINVAL; + } + return __check_ptr_off_reg(env, reg, regno, false); + } + + switch (type) { + /* Pointer types where both fixed and variable offset is explicitly allowed: */ + case PTR_TO_STACK: + case PTR_TO_PACKET: + case PTR_TO_PACKET_META: + case PTR_TO_MAP_KEY: + case PTR_TO_MAP_VALUE: + case PTR_TO_MEM: + case PTR_TO_MEM | MEM_RDONLY: + case PTR_TO_MEM | MEM_RINGBUF: + case PTR_TO_BUF: + case PTR_TO_BUF | MEM_RDONLY: + case SCALAR_VALUE: + return 0; + /* All the rest must be rejected, except PTR_TO_BTF_ID which allows + * fixed offset. + */ + case PTR_TO_BTF_ID: + case PTR_TO_BTF_ID | MEM_ALLOC: + case PTR_TO_BTF_ID | PTR_TRUSTED: + case PTR_TO_BTF_ID | MEM_RCU: + case PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF: + case PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF | MEM_RCU: + /* When referenced PTR_TO_BTF_ID is passed to release function, + * its fixed offset must be 0. In the other cases, fixed offset + * can be non-zero. This was already checked above. So pass + * fixed_off_ok as true to allow fixed offset for all other + * cases. var_off always must be 0 for PTR_TO_BTF_ID, hence we + * still need to do checks instead of returning. + */ + return __check_ptr_off_reg(env, reg, regno, true); + default: + return __check_ptr_off_reg(env, reg, regno, false); + } +} + +static struct bpf_reg_state *get_dynptr_arg_reg(struct bpf_verifier_env *env, + const struct bpf_func_proto *fn, + struct bpf_reg_state *regs) +{ + struct bpf_reg_state *state = NULL; + int i; + + for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++) + if (arg_type_is_dynptr(fn->arg_type[i])) { + if (state) { + verbose(env, "verifier internal error: multiple dynptr args\n"); + return NULL; + } + state = ®s[BPF_REG_1 + i]; + } + + if (!state) + verbose(env, "verifier internal error: no dynptr arg found\n"); + + return state; +} + +static int dynptr_id(struct bpf_verifier_env *env, struct bpf_reg_state *reg) +{ + struct bpf_func_state *state = func(env, reg); + int spi; + + if (reg->type == CONST_PTR_TO_DYNPTR) + return reg->id; + spi = dynptr_get_spi(env, reg); + if (spi < 0) + return spi; + return state->stack[spi].spilled_ptr.id; +} + +static int dynptr_ref_obj_id(struct bpf_verifier_env *env, struct bpf_reg_state *reg) +{ + struct bpf_func_state *state = func(env, reg); + int spi; + + if (reg->type == CONST_PTR_TO_DYNPTR) + return reg->ref_obj_id; + spi = dynptr_get_spi(env, reg); + if (spi < 0) + return spi; + return state->stack[spi].spilled_ptr.ref_obj_id; +} + +static enum bpf_dynptr_type dynptr_get_type(struct bpf_verifier_env *env, + struct bpf_reg_state *reg) +{ + struct bpf_func_state *state = func(env, reg); + int spi; + + if (reg->type == CONST_PTR_TO_DYNPTR) + return reg->dynptr.type; + + spi = __get_spi(reg->off); + if (spi < 0) { + verbose(env, "verifier internal error: invalid spi when querying dynptr type\n"); + return BPF_DYNPTR_TYPE_INVALID; + } + + return state->stack[spi].spilled_ptr.dynptr.type; +} + +static int check_func_arg(struct bpf_verifier_env *env, u32 arg, + struct bpf_call_arg_meta *meta, + const struct bpf_func_proto *fn, + int insn_idx) +{ + u32 regno = BPF_REG_1 + arg; + struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; + enum bpf_arg_type arg_type = fn->arg_type[arg]; + enum bpf_reg_type type = reg->type; + u32 *arg_btf_id = NULL; + int err = 0; + + if (arg_type == ARG_DONTCARE) + return 0; + + err = check_reg_arg(env, regno, SRC_OP); + if (err) + return err; + + if (arg_type == ARG_ANYTHING) { + if (is_pointer_value(env, regno)) { + verbose(env, "R%d leaks addr into helper function\n", + regno); + return -EACCES; + } + return 0; + } + + if (type_is_pkt_pointer(type) && + !may_access_direct_pkt_data(env, meta, BPF_READ)) { + verbose(env, "helper access to the packet is not allowed\n"); + return -EACCES; + } + + if (base_type(arg_type) == ARG_PTR_TO_MAP_VALUE) { + err = resolve_map_arg_type(env, meta, &arg_type); + if (err) + return err; + } + + if (register_is_null(reg) && type_may_be_null(arg_type)) + /* A NULL register has a SCALAR_VALUE type, so skip + * type checking. + */ + goto skip_type_check; + + /* arg_btf_id and arg_size are in a union. */ + if (base_type(arg_type) == ARG_PTR_TO_BTF_ID || + base_type(arg_type) == ARG_PTR_TO_SPIN_LOCK) + arg_btf_id = fn->arg_btf_id[arg]; + + err = check_reg_type(env, regno, arg_type, arg_btf_id, meta); + if (err) + return err; + + err = check_func_arg_reg_off(env, reg, regno, arg_type); + if (err) + return err; + +skip_type_check: + if (arg_type_is_release(arg_type)) { + if (arg_type_is_dynptr(arg_type)) { + struct bpf_func_state *state = func(env, reg); + int spi; + + /* Only dynptr created on stack can be released, thus + * the get_spi and stack state checks for spilled_ptr + * should only be done before process_dynptr_func for + * PTR_TO_STACK. + */ + if (reg->type == PTR_TO_STACK) { + spi = dynptr_get_spi(env, reg); + if (spi < 0 || !state->stack[spi].spilled_ptr.ref_obj_id) { + verbose(env, "arg %d is an unacquired reference\n", regno); + return -EINVAL; + } + } else { + verbose(env, "cannot release unowned const bpf_dynptr\n"); + return -EINVAL; + } + } else if (!reg->ref_obj_id && !register_is_null(reg)) { + verbose(env, "R%d must be referenced when passed to release function\n", + regno); + return -EINVAL; + } + if (meta->release_regno) { + verbose(env, "verifier internal error: more than one release argument\n"); + return -EFAULT; + } + meta->release_regno = regno; + } + + if (reg->ref_obj_id) { + if (meta->ref_obj_id) { + verbose(env, "verifier internal error: more than one arg with ref_obj_id R%d %u %u\n", + regno, reg->ref_obj_id, + meta->ref_obj_id); + return -EFAULT; + } + meta->ref_obj_id = reg->ref_obj_id; + } + + switch (base_type(arg_type)) { + case ARG_CONST_MAP_PTR: + /* bpf_map_xxx(map_ptr) call: remember that map_ptr */ + if (meta->map_ptr) { + /* Use map_uid (which is unique id of inner map) to reject: + * inner_map1 = bpf_map_lookup_elem(outer_map, key1) + * inner_map2 = bpf_map_lookup_elem(outer_map, key2) + * if (inner_map1 && inner_map2) { + * timer = bpf_map_lookup_elem(inner_map1); + * if (timer) + * // mismatch would have been allowed + * bpf_timer_init(timer, inner_map2); + * } + * + * Comparing map_ptr is enough to distinguish normal and outer maps. + */ + if (meta->map_ptr != reg->map_ptr || + meta->map_uid != reg->map_uid) { + verbose(env, + "timer pointer in R1 map_uid=%d doesn't match map pointer in R2 map_uid=%d\n", + meta->map_uid, reg->map_uid); + return -EINVAL; + } + } + meta->map_ptr = reg->map_ptr; + meta->map_uid = reg->map_uid; + break; + case ARG_PTR_TO_MAP_KEY: + /* bpf_map_xxx(..., map_ptr, ..., key) call: + * check that [key, key + map->key_size) are within + * stack limits and initialized + */ + if (!meta->map_ptr) { + /* in function declaration map_ptr must come before + * map_key, so that it's verified and known before + * we have to check map_key here. Otherwise it means + * that kernel subsystem misconfigured verifier + */ + verbose(env, "invalid map_ptr to access map->key\n"); + return -EACCES; + } + err = check_helper_mem_access(env, regno, + meta->map_ptr->key_size, false, + NULL); + break; + case ARG_PTR_TO_MAP_VALUE: + if (type_may_be_null(arg_type) && register_is_null(reg)) + return 0; + + /* bpf_map_xxx(..., map_ptr, ..., value) call: + * check [value, value + map->value_size) validity + */ + if (!meta->map_ptr) { + /* kernel subsystem misconfigured verifier */ + verbose(env, "invalid map_ptr to access map->value\n"); + return -EACCES; + } + meta->raw_mode = arg_type & MEM_UNINIT; + err = check_helper_mem_access(env, regno, + meta->map_ptr->value_size, false, + meta); + break; + case ARG_PTR_TO_PERCPU_BTF_ID: + if (!reg->btf_id) { + verbose(env, "Helper has invalid btf_id in R%d\n", regno); + return -EACCES; + } + meta->ret_btf = reg->btf; + meta->ret_btf_id = reg->btf_id; + break; + case ARG_PTR_TO_SPIN_LOCK: + if (in_rbtree_lock_required_cb(env)) { + verbose(env, "can't spin_{lock,unlock} in rbtree cb\n"); + return -EACCES; + } + if (meta->func_id == BPF_FUNC_spin_lock) { + err = process_spin_lock(env, regno, true); + if (err) + return err; + } else if (meta->func_id == BPF_FUNC_spin_unlock) { + err = process_spin_lock(env, regno, false); + if (err) + return err; + } else { + verbose(env, "verifier internal error\n"); + return -EFAULT; + } + break; + case ARG_PTR_TO_TIMER: + err = process_timer_func(env, regno, meta); + if (err) + return err; + break; + case ARG_PTR_TO_FUNC: + meta->subprogno = reg->subprogno; + break; + case ARG_PTR_TO_MEM: + /* The access to this pointer is only checked when we hit the + * next is_mem_size argument below. + */ + meta->raw_mode = arg_type & MEM_UNINIT; + if (arg_type & MEM_FIXED_SIZE) { + err = check_helper_mem_access(env, regno, + fn->arg_size[arg], false, + meta); + } + break; + case ARG_CONST_SIZE: + err = check_mem_size_reg(env, reg, regno, false, meta); + break; + case ARG_CONST_SIZE_OR_ZERO: + err = check_mem_size_reg(env, reg, regno, true, meta); + break; + case ARG_PTR_TO_DYNPTR: + err = process_dynptr_func(env, regno, insn_idx, arg_type, 0); + if (err) + return err; + break; + case ARG_CONST_ALLOC_SIZE_OR_ZERO: + if (!tnum_is_const(reg->var_off)) { + verbose(env, "R%d is not a known constant'\n", + regno); + return -EACCES; + } + meta->mem_size = reg->var_off.value; + err = mark_chain_precision(env, regno); + if (err) + return err; + break; + case ARG_PTR_TO_INT: + case ARG_PTR_TO_LONG: + { + int size = int_ptr_type_to_size(arg_type); + + err = check_helper_mem_access(env, regno, size, false, meta); + if (err) + return err; + err = check_ptr_alignment(env, reg, 0, size, true); + break; + } + case ARG_PTR_TO_CONST_STR: + { + struct bpf_map *map = reg->map_ptr; + int map_off; + u64 map_addr; + char *str_ptr; + + if (!bpf_map_is_rdonly(map)) { + verbose(env, "R%d does not point to a readonly map'\n", regno); + return -EACCES; + } + + if (!tnum_is_const(reg->var_off)) { + verbose(env, "R%d is not a constant address'\n", regno); + return -EACCES; + } + + if (!map->ops->map_direct_value_addr) { + verbose(env, "no direct value access support for this map type\n"); + return -EACCES; + } + + err = check_map_access(env, regno, reg->off, + map->value_size - reg->off, false, + ACCESS_HELPER); + if (err) + return err; + + map_off = reg->off + reg->var_off.value; + err = map->ops->map_direct_value_addr(map, &map_addr, map_off); + if (err) { + verbose(env, "direct value access on string failed\n"); + return err; + } + + str_ptr = (char *)(long)(map_addr); + if (!strnchr(str_ptr + map_off, map->value_size - map_off, 0)) { + verbose(env, "string is not zero-terminated\n"); + return -EINVAL; + } + break; + } + case ARG_PTR_TO_KPTR: + err = process_kptr_func(env, regno, meta); + if (err) + return err; + break; + } + + return err; +} + +static bool may_update_sockmap(struct bpf_verifier_env *env, int func_id) +{ + enum bpf_attach_type eatype = env->prog->expected_attach_type; + enum bpf_prog_type type = resolve_prog_type(env->prog); + + if (func_id != BPF_FUNC_map_update_elem) + return false; + + /* It's not possible to get access to a locked struct sock in these + * contexts, so updating is safe. + */ + switch (type) { + case BPF_PROG_TYPE_TRACING: + if (eatype == BPF_TRACE_ITER) + return true; + break; + case BPF_PROG_TYPE_SOCKET_FILTER: + case BPF_PROG_TYPE_SCHED_CLS: + case BPF_PROG_TYPE_SCHED_ACT: + case BPF_PROG_TYPE_XDP: + case BPF_PROG_TYPE_SK_REUSEPORT: + case BPF_PROG_TYPE_FLOW_DISSECTOR: + case BPF_PROG_TYPE_SK_LOOKUP: + return true; + default: + break; + } + + verbose(env, "cannot update sockmap in this context\n"); + return false; +} + +static bool allow_tail_call_in_subprogs(struct bpf_verifier_env *env) +{ + return env->prog->jit_requested && + bpf_jit_supports_subprog_tailcalls(); +} + +static int check_map_func_compatibility(struct bpf_verifier_env *env, + struct bpf_map *map, int func_id) +{ + if (!map) + return 0; + + /* We need a two way check, first is from map perspective ... */ + switch (map->map_type) { + case BPF_MAP_TYPE_PROG_ARRAY: + if (func_id != BPF_FUNC_tail_call) + goto error; + break; + case BPF_MAP_TYPE_PERF_EVENT_ARRAY: + if (func_id != BPF_FUNC_perf_event_read && + func_id != BPF_FUNC_perf_event_output && + func_id != BPF_FUNC_skb_output && + func_id != BPF_FUNC_perf_event_read_value && + func_id != BPF_FUNC_xdp_output) + goto error; + break; + case BPF_MAP_TYPE_RINGBUF: + if (func_id != BPF_FUNC_ringbuf_output && + func_id != BPF_FUNC_ringbuf_reserve && + func_id != BPF_FUNC_ringbuf_query && + func_id != BPF_FUNC_ringbuf_reserve_dynptr && + func_id != BPF_FUNC_ringbuf_submit_dynptr && + func_id != BPF_FUNC_ringbuf_discard_dynptr) + goto error; + break; + case BPF_MAP_TYPE_USER_RINGBUF: + if (func_id != BPF_FUNC_user_ringbuf_drain) + goto error; + break; + case BPF_MAP_TYPE_STACK_TRACE: + if (func_id != BPF_FUNC_get_stackid) + goto error; + break; + case BPF_MAP_TYPE_CGROUP_ARRAY: + if (func_id != BPF_FUNC_skb_under_cgroup && + func_id != BPF_FUNC_current_task_under_cgroup) + goto error; + break; + case BPF_MAP_TYPE_CGROUP_STORAGE: + case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE: + if (func_id != BPF_FUNC_get_local_storage) + goto error; + break; + case BPF_MAP_TYPE_DEVMAP: + case BPF_MAP_TYPE_DEVMAP_HASH: + if (func_id != BPF_FUNC_redirect_map && + func_id != BPF_FUNC_map_lookup_elem) + goto error; + break; + /* Restrict bpf side of cpumap and xskmap, open when use-cases + * appear. + */ + case BPF_MAP_TYPE_CPUMAP: + if (func_id != BPF_FUNC_redirect_map) + goto error; + break; + case BPF_MAP_TYPE_XSKMAP: + if (func_id != BPF_FUNC_redirect_map && + func_id != BPF_FUNC_map_lookup_elem) + goto error; + break; + case BPF_MAP_TYPE_ARRAY_OF_MAPS: + case BPF_MAP_TYPE_HASH_OF_MAPS: + if (func_id != BPF_FUNC_map_lookup_elem) + goto error; + break; + case BPF_MAP_TYPE_SOCKMAP: + if (func_id != BPF_FUNC_sk_redirect_map && + func_id != BPF_FUNC_sock_map_update && + func_id != BPF_FUNC_map_delete_elem && + func_id != BPF_FUNC_msg_redirect_map && + func_id != BPF_FUNC_sk_select_reuseport && + func_id != BPF_FUNC_map_lookup_elem && + !may_update_sockmap(env, func_id)) + goto error; + break; + case BPF_MAP_TYPE_SOCKHASH: + if (func_id != BPF_FUNC_sk_redirect_hash && + func_id != BPF_FUNC_sock_hash_update && + func_id != BPF_FUNC_map_delete_elem && + func_id != BPF_FUNC_msg_redirect_hash && + func_id != BPF_FUNC_sk_select_reuseport && + func_id != BPF_FUNC_map_lookup_elem && + !may_update_sockmap(env, func_id)) + goto error; + break; + case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY: + if (func_id != BPF_FUNC_sk_select_reuseport) + goto error; + break; + case BPF_MAP_TYPE_QUEUE: + case BPF_MAP_TYPE_STACK: + if (func_id != BPF_FUNC_map_peek_elem && + func_id != BPF_FUNC_map_pop_elem && + func_id != BPF_FUNC_map_push_elem) + goto error; + break; + case BPF_MAP_TYPE_SK_STORAGE: + if (func_id != BPF_FUNC_sk_storage_get && + func_id != BPF_FUNC_sk_storage_delete && + func_id != BPF_FUNC_kptr_xchg) + goto error; + break; + case BPF_MAP_TYPE_INODE_STORAGE: + if (func_id != BPF_FUNC_inode_storage_get && + func_id != BPF_FUNC_inode_storage_delete && + func_id != BPF_FUNC_kptr_xchg) + goto error; + break; + case BPF_MAP_TYPE_TASK_STORAGE: + if (func_id != BPF_FUNC_task_storage_get && + func_id != BPF_FUNC_task_storage_delete && + func_id != BPF_FUNC_kptr_xchg) + goto error; + break; + case BPF_MAP_TYPE_CGRP_STORAGE: + if (func_id != BPF_FUNC_cgrp_storage_get && + func_id != BPF_FUNC_cgrp_storage_delete && + func_id != BPF_FUNC_kptr_xchg) + goto error; + break; + case BPF_MAP_TYPE_BLOOM_FILTER: + if (func_id != BPF_FUNC_map_peek_elem && + func_id != BPF_FUNC_map_push_elem) + goto error; + break; + default: + break; + } + + /* ... and second from the function itself. */ + switch (func_id) { + case BPF_FUNC_tail_call: + if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY) + goto error; + if (env->subprog_cnt > 1 && !allow_tail_call_in_subprogs(env)) { + verbose(env, "tail_calls are not allowed in non-JITed programs with bpf-to-bpf calls\n"); + return -EINVAL; + } + break; + case BPF_FUNC_perf_event_read: + case BPF_FUNC_perf_event_output: + case BPF_FUNC_perf_event_read_value: + case BPF_FUNC_skb_output: + case BPF_FUNC_xdp_output: + if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) + goto error; + break; + case BPF_FUNC_ringbuf_output: + case BPF_FUNC_ringbuf_reserve: + case BPF_FUNC_ringbuf_query: + case BPF_FUNC_ringbuf_reserve_dynptr: + case BPF_FUNC_ringbuf_submit_dynptr: + case BPF_FUNC_ringbuf_discard_dynptr: + if (map->map_type != BPF_MAP_TYPE_RINGBUF) + goto error; + break; + case BPF_FUNC_user_ringbuf_drain: + if (map->map_type != BPF_MAP_TYPE_USER_RINGBUF) + goto error; + break; + case BPF_FUNC_get_stackid: + if (map->map_type != BPF_MAP_TYPE_STACK_TRACE) + goto error; + break; + case BPF_FUNC_current_task_under_cgroup: + case BPF_FUNC_skb_under_cgroup: + if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY) + goto error; + break; + case BPF_FUNC_redirect_map: + if (map->map_type != BPF_MAP_TYPE_DEVMAP && + map->map_type != BPF_MAP_TYPE_DEVMAP_HASH && + map->map_type != BPF_MAP_TYPE_CPUMAP && + map->map_type != BPF_MAP_TYPE_XSKMAP) + goto error; + break; + case BPF_FUNC_sk_redirect_map: + case BPF_FUNC_msg_redirect_map: + case BPF_FUNC_sock_map_update: + if (map->map_type != BPF_MAP_TYPE_SOCKMAP) + goto error; + break; + case BPF_FUNC_sk_redirect_hash: + case BPF_FUNC_msg_redirect_hash: + case BPF_FUNC_sock_hash_update: + if (map->map_type != BPF_MAP_TYPE_SOCKHASH) + goto error; + break; + case BPF_FUNC_get_local_storage: + if (map->map_type != BPF_MAP_TYPE_CGROUP_STORAGE && + map->map_type != BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE) + goto error; + break; + case BPF_FUNC_sk_select_reuseport: + if (map->map_type != BPF_MAP_TYPE_REUSEPORT_SOCKARRAY && + map->map_type != BPF_MAP_TYPE_SOCKMAP && + map->map_type != BPF_MAP_TYPE_SOCKHASH) + goto error; + break; + case BPF_FUNC_map_pop_elem: + if (map->map_type != BPF_MAP_TYPE_QUEUE && + map->map_type != BPF_MAP_TYPE_STACK) + goto error; + break; + case BPF_FUNC_map_peek_elem: + case BPF_FUNC_map_push_elem: + if (map->map_type != BPF_MAP_TYPE_QUEUE && + map->map_type != BPF_MAP_TYPE_STACK && + map->map_type != BPF_MAP_TYPE_BLOOM_FILTER) + goto error; + break; + case BPF_FUNC_map_lookup_percpu_elem: + if (map->map_type != BPF_MAP_TYPE_PERCPU_ARRAY && + map->map_type != BPF_MAP_TYPE_PERCPU_HASH && + map->map_type != BPF_MAP_TYPE_LRU_PERCPU_HASH) + goto error; + break; + case BPF_FUNC_sk_storage_get: + case BPF_FUNC_sk_storage_delete: + if (map->map_type != BPF_MAP_TYPE_SK_STORAGE) + goto error; + break; + case BPF_FUNC_inode_storage_get: + case BPF_FUNC_inode_storage_delete: + if (map->map_type != BPF_MAP_TYPE_INODE_STORAGE) + goto error; + break; + case BPF_FUNC_task_storage_get: + case BPF_FUNC_task_storage_delete: + if (map->map_type != BPF_MAP_TYPE_TASK_STORAGE) + goto error; + break; + case BPF_FUNC_cgrp_storage_get: + case BPF_FUNC_cgrp_storage_delete: + if (map->map_type != BPF_MAP_TYPE_CGRP_STORAGE) + goto error; + break; + default: + break; + } + + return 0; +error: + verbose(env, "cannot pass map_type %d into func %s#%d\n", + map->map_type, func_id_name(func_id), func_id); + return -EINVAL; +} + +static bool check_raw_mode_ok(const struct bpf_func_proto *fn) +{ + int count = 0; + + if (fn->arg1_type == ARG_PTR_TO_UNINIT_MEM) + count++; + if (fn->arg2_type == ARG_PTR_TO_UNINIT_MEM) + count++; + if (fn->arg3_type == ARG_PTR_TO_UNINIT_MEM) + count++; + if (fn->arg4_type == ARG_PTR_TO_UNINIT_MEM) + count++; + if (fn->arg5_type == ARG_PTR_TO_UNINIT_MEM) + count++; + + /* We only support one arg being in raw mode at the moment, + * which is sufficient for the helper functions we have + * right now. + */ + return count <= 1; +} + +static bool check_args_pair_invalid(const struct bpf_func_proto *fn, int arg) +{ + bool is_fixed = fn->arg_type[arg] & MEM_FIXED_SIZE; + bool has_size = fn->arg_size[arg] != 0; + bool is_next_size = false; + + if (arg + 1 < ARRAY_SIZE(fn->arg_type)) + is_next_size = arg_type_is_mem_size(fn->arg_type[arg + 1]); + + if (base_type(fn->arg_type[arg]) != ARG_PTR_TO_MEM) + return is_next_size; + + return has_size == is_next_size || is_next_size == is_fixed; +} + +static bool check_arg_pair_ok(const struct bpf_func_proto *fn) +{ + /* bpf_xxx(..., buf, len) call will access 'len' + * bytes from memory 'buf'. Both arg types need + * to be paired, so make sure there's no buggy + * helper function specification. + */ + if (arg_type_is_mem_size(fn->arg1_type) || + check_args_pair_invalid(fn, 0) || + check_args_pair_invalid(fn, 1) || + check_args_pair_invalid(fn, 2) || + check_args_pair_invalid(fn, 3) || + check_args_pair_invalid(fn, 4)) + return false; + + return true; +} + +static bool check_btf_id_ok(const struct bpf_func_proto *fn) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(fn->arg_type); i++) { + if (base_type(fn->arg_type[i]) == ARG_PTR_TO_BTF_ID) + return !!fn->arg_btf_id[i]; + if (base_type(fn->arg_type[i]) == ARG_PTR_TO_SPIN_LOCK) + return fn->arg_btf_id[i] == BPF_PTR_POISON; + if (base_type(fn->arg_type[i]) != ARG_PTR_TO_BTF_ID && fn->arg_btf_id[i] && + /* arg_btf_id and arg_size are in a union. */ + (base_type(fn->arg_type[i]) != ARG_PTR_TO_MEM || + !(fn->arg_type[i] & MEM_FIXED_SIZE))) + return false; + } + + return true; +} + +static int check_func_proto(const struct bpf_func_proto *fn, int func_id) +{ + return check_raw_mode_ok(fn) && + check_arg_pair_ok(fn) && + check_btf_id_ok(fn) ? 0 : -EINVAL; +} + +/* Packet data might have moved, any old PTR_TO_PACKET[_META,_END] + * are now invalid, so turn them into unknown SCALAR_VALUE. + * + * This also applies to dynptr slices belonging to skb and xdp dynptrs, + * since these slices point to packet data. + */ +static void clear_all_pkt_pointers(struct bpf_verifier_env *env) +{ + struct bpf_func_state *state; + struct bpf_reg_state *reg; + + bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({ + if (reg_is_pkt_pointer_any(reg) || reg_is_dynptr_slice_pkt(reg)) + mark_reg_invalid(env, reg); + })); +} + +enum { + AT_PKT_END = -1, + BEYOND_PKT_END = -2, +}; + +static void mark_pkt_end(struct bpf_verifier_state *vstate, int regn, bool range_open) +{ + struct bpf_func_state *state = vstate->frame[vstate->curframe]; + struct bpf_reg_state *reg = &state->regs[regn]; + + if (reg->type != PTR_TO_PACKET) + /* PTR_TO_PACKET_META is not supported yet */ + return; + + /* The 'reg' is pkt > pkt_end or pkt >= pkt_end. + * How far beyond pkt_end it goes is unknown. + * if (!range_open) it's the case of pkt >= pkt_end + * if (range_open) it's the case of pkt > pkt_end + * hence this pointer is at least 1 byte bigger than pkt_end + */ + if (range_open) + reg->range = BEYOND_PKT_END; + else + reg->range = AT_PKT_END; +} + +/* The pointer with the specified id has released its reference to kernel + * resources. Identify all copies of the same pointer and clear the reference. + */ +static int release_reference(struct bpf_verifier_env *env, + int ref_obj_id) +{ + struct bpf_func_state *state; + struct bpf_reg_state *reg; + int err; + + err = release_reference_state(cur_func(env), ref_obj_id); + if (err) + return err; + + bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({ + if (reg->ref_obj_id == ref_obj_id) + mark_reg_invalid(env, reg); + })); + + return 0; +} + +static void invalidate_non_owning_refs(struct bpf_verifier_env *env) +{ + struct bpf_func_state *unused; + struct bpf_reg_state *reg; + + bpf_for_each_reg_in_vstate(env->cur_state, unused, reg, ({ + if (type_is_non_owning_ref(reg->type)) + mark_reg_invalid(env, reg); + })); +} + +static void clear_caller_saved_regs(struct bpf_verifier_env *env, + struct bpf_reg_state *regs) +{ + int i; + + /* after the call registers r0 - r5 were scratched */ + for (i = 0; i < CALLER_SAVED_REGS; i++) { + mark_reg_not_init(env, regs, caller_saved[i]); + __check_reg_arg(env, regs, caller_saved[i], DST_OP_NO_MARK); + } +} + +typedef int (*set_callee_state_fn)(struct bpf_verifier_env *env, + struct bpf_func_state *caller, + struct bpf_func_state *callee, + int insn_idx); + +static int set_callee_state(struct bpf_verifier_env *env, + struct bpf_func_state *caller, + struct bpf_func_state *callee, int insn_idx); + +static int setup_func_entry(struct bpf_verifier_env *env, int subprog, int callsite, + set_callee_state_fn set_callee_state_cb, + struct bpf_verifier_state *state) +{ + struct bpf_func_state *caller, *callee; + int err; + + if (state->curframe + 1 >= MAX_CALL_FRAMES) { + verbose(env, "the call stack of %d frames is too deep\n", + state->curframe + 2); + return -E2BIG; + } + + if (state->frame[state->curframe + 1]) { + verbose(env, "verifier bug. Frame %d already allocated\n", + state->curframe + 1); + return -EFAULT; + } + + caller = state->frame[state->curframe]; + callee = kzalloc(sizeof(*callee), GFP_KERNEL); + if (!callee) + return -ENOMEM; + state->frame[state->curframe + 1] = callee; + + /* callee cannot access r0, r6 - r9 for reading and has to write + * into its own stack before reading from it. + * callee can read/write into caller's stack + */ + init_func_state(env, callee, + /* remember the callsite, it will be used by bpf_exit */ + callsite, + state->curframe + 1 /* frameno within this callchain */, + subprog /* subprog number within this prog */); + /* Transfer references to the callee */ + err = copy_reference_state(callee, caller); + err = err ?: set_callee_state_cb(env, caller, callee, callsite); + if (err) + goto err_out; + + /* only increment it after check_reg_arg() finished */ + state->curframe++; + + return 0; + +err_out: + free_func_state(callee); + state->frame[state->curframe + 1] = NULL; + return err; +} + +static int push_callback_call(struct bpf_verifier_env *env, struct bpf_insn *insn, + int insn_idx, int subprog, + set_callee_state_fn set_callee_state_cb) +{ + struct bpf_verifier_state *state = env->cur_state, *callback_state; + struct bpf_func_state *caller, *callee; + int err; + + caller = state->frame[state->curframe]; + err = btf_check_subprog_call(env, subprog, caller->regs); + if (err == -EFAULT) + return err; + + /* set_callee_state is used for direct subprog calls, but we are + * interested in validating only BPF helpers that can call subprogs as + * callbacks + */ + if (bpf_pseudo_kfunc_call(insn) && + !is_sync_callback_calling_kfunc(insn->imm)) { + verbose(env, "verifier bug: kfunc %s#%d not marked as callback-calling\n", + func_id_name(insn->imm), insn->imm); + return -EFAULT; + } else if (!bpf_pseudo_kfunc_call(insn) && + !is_callback_calling_function(insn->imm)) { /* helper */ + verbose(env, "verifier bug: helper %s#%d not marked as callback-calling\n", + func_id_name(insn->imm), insn->imm); + return -EFAULT; + } + + if (insn->code == (BPF_JMP | BPF_CALL) && + insn->src_reg == 0 && + insn->imm == BPF_FUNC_timer_set_callback) { + struct bpf_verifier_state *async_cb; + + /* there is no real recursion here. timer callbacks are async */ + env->subprog_info[subprog].is_async_cb = true; + async_cb = push_async_cb(env, env->subprog_info[subprog].start, + insn_idx, subprog); + if (!async_cb) + return -EFAULT; + callee = async_cb->frame[0]; + callee->async_entry_cnt = caller->async_entry_cnt + 1; + + /* Convert bpf_timer_set_callback() args into timer callback args */ + err = set_callee_state_cb(env, caller, callee, insn_idx); + if (err) + return err; + + return 0; + } + + /* for callback functions enqueue entry to callback and + * proceed with next instruction within current frame. + */ + callback_state = push_stack(env, env->subprog_info[subprog].start, insn_idx, false); + if (!callback_state) + return -ENOMEM; + + err = setup_func_entry(env, subprog, insn_idx, set_callee_state_cb, + callback_state); + if (err) + return err; + + callback_state->callback_unroll_depth++; + callback_state->frame[callback_state->curframe - 1]->callback_depth++; + caller->callback_depth = 0; + return 0; +} + +static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn, + int *insn_idx) +{ + struct bpf_verifier_state *state = env->cur_state; + struct bpf_func_state *caller; + int err, subprog, target_insn; + + target_insn = *insn_idx + insn->imm + 1; + subprog = find_subprog(env, target_insn); + if (subprog < 0) { + verbose(env, "verifier bug. No program starts at insn %d\n", target_insn); + return -EFAULT; + } + + caller = state->frame[state->curframe]; + err = btf_check_subprog_call(env, subprog, caller->regs); + if (err == -EFAULT) + return err; + if (subprog_is_global(env, subprog)) { + if (err) { + verbose(env, "Caller passes invalid args into func#%d\n", subprog); + return err; + } + + if (env->log.level & BPF_LOG_LEVEL) + verbose(env, "Func#%d is global and valid. Skipping.\n", subprog); + clear_caller_saved_regs(env, caller->regs); + + /* All global functions return a 64-bit SCALAR_VALUE */ + mark_reg_unknown(env, caller->regs, BPF_REG_0); + caller->regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG; + + /* continue with next insn after call */ + return 0; + } + + /* for regular function entry setup new frame and continue + * from that frame. + */ + err = setup_func_entry(env, subprog, *insn_idx, set_callee_state, state); + if (err) + return err; + + clear_caller_saved_regs(env, caller->regs); + + /* and go analyze first insn of the callee */ + *insn_idx = env->subprog_info[subprog].start - 1; + + if (env->log.level & BPF_LOG_LEVEL) { + verbose(env, "caller:\n"); + print_verifier_state(env, caller, true); + verbose(env, "callee:\n"); + print_verifier_state(env, state->frame[state->curframe], true); + } + + return 0; +} + +int map_set_for_each_callback_args(struct bpf_verifier_env *env, + struct bpf_func_state *caller, + struct bpf_func_state *callee) +{ + /* bpf_for_each_map_elem(struct bpf_map *map, void *callback_fn, + * void *callback_ctx, u64 flags); + * callback_fn(struct bpf_map *map, void *key, void *value, + * void *callback_ctx); + */ + callee->regs[BPF_REG_1] = caller->regs[BPF_REG_1]; + + callee->regs[BPF_REG_2].type = PTR_TO_MAP_KEY; + __mark_reg_known_zero(&callee->regs[BPF_REG_2]); + callee->regs[BPF_REG_2].map_ptr = caller->regs[BPF_REG_1].map_ptr; + + callee->regs[BPF_REG_3].type = PTR_TO_MAP_VALUE; + __mark_reg_known_zero(&callee->regs[BPF_REG_3]); + callee->regs[BPF_REG_3].map_ptr = caller->regs[BPF_REG_1].map_ptr; + + /* pointer to stack or null */ + callee->regs[BPF_REG_4] = caller->regs[BPF_REG_3]; + + /* unused */ + __mark_reg_not_init(env, &callee->regs[BPF_REG_5]); + return 0; +} + +static int set_callee_state(struct bpf_verifier_env *env, + struct bpf_func_state *caller, + struct bpf_func_state *callee, int insn_idx) +{ + int i; + + /* copy r1 - r5 args that callee can access. The copy includes parent + * pointers, which connects us up to the liveness chain + */ + for (i = BPF_REG_1; i <= BPF_REG_5; i++) + callee->regs[i] = caller->regs[i]; + return 0; +} + +static int set_map_elem_callback_state(struct bpf_verifier_env *env, + struct bpf_func_state *caller, + struct bpf_func_state *callee, + int insn_idx) +{ + struct bpf_insn_aux_data *insn_aux = &env->insn_aux_data[insn_idx]; + struct bpf_map *map; + int err; + + if (bpf_map_ptr_poisoned(insn_aux)) { + verbose(env, "tail_call abusing map_ptr\n"); + return -EINVAL; + } + + map = BPF_MAP_PTR(insn_aux->map_ptr_state); + if (!map->ops->map_set_for_each_callback_args || + !map->ops->map_for_each_callback) { + verbose(env, "callback function not allowed for map\n"); + return -ENOTSUPP; + } + + err = map->ops->map_set_for_each_callback_args(env, caller, callee); + if (err) + return err; + + callee->in_callback_fn = true; + callee->callback_ret_range = tnum_range(0, 1); + return 0; +} + +static int set_loop_callback_state(struct bpf_verifier_env *env, + struct bpf_func_state *caller, + struct bpf_func_state *callee, + int insn_idx) +{ + /* bpf_loop(u32 nr_loops, void *callback_fn, void *callback_ctx, + * u64 flags); + * callback_fn(u32 index, void *callback_ctx); + */ + callee->regs[BPF_REG_1].type = SCALAR_VALUE; + callee->regs[BPF_REG_2] = caller->regs[BPF_REG_3]; + + /* unused */ + __mark_reg_not_init(env, &callee->regs[BPF_REG_3]); + __mark_reg_not_init(env, &callee->regs[BPF_REG_4]); + __mark_reg_not_init(env, &callee->regs[BPF_REG_5]); + + callee->in_callback_fn = true; + callee->callback_ret_range = tnum_range(0, 1); + return 0; +} + +static int set_timer_callback_state(struct bpf_verifier_env *env, + struct bpf_func_state *caller, + struct bpf_func_state *callee, + int insn_idx) +{ + struct bpf_map *map_ptr = caller->regs[BPF_REG_1].map_ptr; + + /* bpf_timer_set_callback(struct bpf_timer *timer, void *callback_fn); + * callback_fn(struct bpf_map *map, void *key, void *value); + */ + callee->regs[BPF_REG_1].type = CONST_PTR_TO_MAP; + __mark_reg_known_zero(&callee->regs[BPF_REG_1]); + callee->regs[BPF_REG_1].map_ptr = map_ptr; + + callee->regs[BPF_REG_2].type = PTR_TO_MAP_KEY; + __mark_reg_known_zero(&callee->regs[BPF_REG_2]); + callee->regs[BPF_REG_2].map_ptr = map_ptr; + + callee->regs[BPF_REG_3].type = PTR_TO_MAP_VALUE; + __mark_reg_known_zero(&callee->regs[BPF_REG_3]); + callee->regs[BPF_REG_3].map_ptr = map_ptr; + + /* unused */ + __mark_reg_not_init(env, &callee->regs[BPF_REG_4]); + __mark_reg_not_init(env, &callee->regs[BPF_REG_5]); + callee->in_async_callback_fn = true; + callee->callback_ret_range = tnum_range(0, 1); + return 0; +} + +static int set_find_vma_callback_state(struct bpf_verifier_env *env, + struct bpf_func_state *caller, + struct bpf_func_state *callee, + int insn_idx) +{ + /* bpf_find_vma(struct task_struct *task, u64 addr, + * void *callback_fn, void *callback_ctx, u64 flags) + * (callback_fn)(struct task_struct *task, + * struct vm_area_struct *vma, void *callback_ctx); + */ + callee->regs[BPF_REG_1] = caller->regs[BPF_REG_1]; + + callee->regs[BPF_REG_2].type = PTR_TO_BTF_ID; + __mark_reg_known_zero(&callee->regs[BPF_REG_2]); + callee->regs[BPF_REG_2].btf = btf_vmlinux; + callee->regs[BPF_REG_2].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_VMA], + + /* pointer to stack or null */ + callee->regs[BPF_REG_3] = caller->regs[BPF_REG_4]; + + /* unused */ + __mark_reg_not_init(env, &callee->regs[BPF_REG_4]); + __mark_reg_not_init(env, &callee->regs[BPF_REG_5]); + callee->in_callback_fn = true; + callee->callback_ret_range = tnum_range(0, 1); + return 0; +} + +static int set_user_ringbuf_callback_state(struct bpf_verifier_env *env, + struct bpf_func_state *caller, + struct bpf_func_state *callee, + int insn_idx) +{ + /* bpf_user_ringbuf_drain(struct bpf_map *map, void *callback_fn, void + * callback_ctx, u64 flags); + * callback_fn(const struct bpf_dynptr_t* dynptr, void *callback_ctx); + */ + __mark_reg_not_init(env, &callee->regs[BPF_REG_0]); + mark_dynptr_cb_reg(env, &callee->regs[BPF_REG_1], BPF_DYNPTR_TYPE_LOCAL); + callee->regs[BPF_REG_2] = caller->regs[BPF_REG_3]; + + /* unused */ + __mark_reg_not_init(env, &callee->regs[BPF_REG_3]); + __mark_reg_not_init(env, &callee->regs[BPF_REG_4]); + __mark_reg_not_init(env, &callee->regs[BPF_REG_5]); + + callee->in_callback_fn = true; + callee->callback_ret_range = tnum_range(0, 1); + return 0; +} + +static int set_rbtree_add_callback_state(struct bpf_verifier_env *env, + struct bpf_func_state *caller, + struct bpf_func_state *callee, + int insn_idx) +{ + /* void bpf_rbtree_add_impl(struct bpf_rb_root *root, struct bpf_rb_node *node, + * bool (less)(struct bpf_rb_node *a, const struct bpf_rb_node *b)); + * + * 'struct bpf_rb_node *node' arg to bpf_rbtree_add_impl is the same PTR_TO_BTF_ID w/ offset + * that 'less' callback args will be receiving. However, 'node' arg was release_reference'd + * by this point, so look at 'root' + */ + struct btf_field *field; + + field = reg_find_field_offset(&caller->regs[BPF_REG_1], caller->regs[BPF_REG_1].off, + BPF_RB_ROOT); + if (!field || !field->graph_root.value_btf_id) + return -EFAULT; + + mark_reg_graph_node(callee->regs, BPF_REG_1, &field->graph_root); + ref_set_non_owning(env, &callee->regs[BPF_REG_1]); + mark_reg_graph_node(callee->regs, BPF_REG_2, &field->graph_root); + ref_set_non_owning(env, &callee->regs[BPF_REG_2]); + + __mark_reg_not_init(env, &callee->regs[BPF_REG_3]); + __mark_reg_not_init(env, &callee->regs[BPF_REG_4]); + __mark_reg_not_init(env, &callee->regs[BPF_REG_5]); + callee->in_callback_fn = true; + callee->callback_ret_range = tnum_range(0, 1); + return 0; +} + +static bool is_rbtree_lock_required_kfunc(u32 btf_id); + +/* Are we currently verifying the callback for a rbtree helper that must + * be called with lock held? If so, no need to complain about unreleased + * lock + */ +static bool in_rbtree_lock_required_cb(struct bpf_verifier_env *env) +{ + struct bpf_verifier_state *state = env->cur_state; + struct bpf_insn *insn = env->prog->insnsi; + struct bpf_func_state *callee; + int kfunc_btf_id; + + if (!state->curframe) + return false; + + callee = state->frame[state->curframe]; + + if (!callee->in_callback_fn) + return false; + + kfunc_btf_id = insn[callee->callsite].imm; + return is_rbtree_lock_required_kfunc(kfunc_btf_id); +} + +static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx) +{ + struct bpf_verifier_state *state = env->cur_state, *prev_st; + struct bpf_func_state *caller, *callee; + struct bpf_reg_state *r0; + bool in_callback_fn; + int err; + + callee = state->frame[state->curframe]; + r0 = &callee->regs[BPF_REG_0]; + if (r0->type == PTR_TO_STACK) { + /* technically it's ok to return caller's stack pointer + * (or caller's caller's pointer) back to the caller, + * since these pointers are valid. Only current stack + * pointer will be invalid as soon as function exits, + * but let's be conservative + */ + verbose(env, "cannot return stack pointer to the caller\n"); + return -EINVAL; + } + + caller = state->frame[state->curframe - 1]; + if (callee->in_callback_fn) { + /* enforce R0 return value range [0, 1]. */ + struct tnum range = callee->callback_ret_range; + + if (r0->type != SCALAR_VALUE) { + verbose(env, "R0 not a scalar value\n"); + return -EACCES; + } + + /* we are going to rely on register's precise value */ + err = mark_reg_read(env, r0, r0->parent, REG_LIVE_READ64); + err = err ?: mark_chain_precision(env, BPF_REG_0); + if (err) + return err; + + if (!tnum_in(range, r0->var_off)) { + verbose_invalid_scalar(env, r0, &range, "callback return", "R0"); + return -EINVAL; + } + if (!calls_callback(env, callee->callsite)) { + verbose(env, "BUG: in callback at %d, callsite %d !calls_callback\n", + *insn_idx, callee->callsite); + return -EFAULT; + } + } else { + /* return to the caller whatever r0 had in the callee */ + caller->regs[BPF_REG_0] = *r0; + } + + /* callback_fn frame should have released its own additions to parent's + * reference state at this point, or check_reference_leak would + * complain, hence it must be the same as the caller. There is no need + * to copy it back. + */ + if (!callee->in_callback_fn) { + /* Transfer references to the caller */ + err = copy_reference_state(caller, callee); + if (err) + return err; + } + + /* for callbacks like bpf_loop or bpf_for_each_map_elem go back to callsite, + * there function call logic would reschedule callback visit. If iteration + * converges is_state_visited() would prune that visit eventually. + */ + in_callback_fn = callee->in_callback_fn; + if (in_callback_fn) + *insn_idx = callee->callsite; + else + *insn_idx = callee->callsite + 1; + + if (env->log.level & BPF_LOG_LEVEL) { + verbose(env, "returning from callee:\n"); + print_verifier_state(env, callee, true); + verbose(env, "to caller at %d:\n", *insn_idx); + print_verifier_state(env, caller, true); + } + /* clear everything in the callee */ + free_func_state(callee); + state->frame[state->curframe--] = NULL; + + /* for callbacks widen imprecise scalars to make programs like below verify: + * + * struct ctx { int i; } + * void cb(int idx, struct ctx *ctx) { ctx->i++; ... } + * ... + * struct ctx = { .i = 0; } + * bpf_loop(100, cb, &ctx, 0); + * + * This is similar to what is done in process_iter_next_call() for open + * coded iterators. + */ + prev_st = in_callback_fn ? find_prev_entry(env, state, *insn_idx) : NULL; + if (prev_st) { + err = widen_imprecise_scalars(env, prev_st, state); + if (err) + return err; + } + return 0; +} + +static void do_refine_retval_range(struct bpf_reg_state *regs, int ret_type, + int func_id, + struct bpf_call_arg_meta *meta) +{ + struct bpf_reg_state *ret_reg = ®s[BPF_REG_0]; + + if (ret_type != RET_INTEGER) + return; + + switch (func_id) { + case BPF_FUNC_get_stack: + case BPF_FUNC_get_task_stack: + case BPF_FUNC_probe_read_str: + case BPF_FUNC_probe_read_kernel_str: + case BPF_FUNC_probe_read_user_str: + ret_reg->smax_value = meta->msize_max_value; + ret_reg->s32_max_value = meta->msize_max_value; + ret_reg->smin_value = -MAX_ERRNO; + ret_reg->s32_min_value = -MAX_ERRNO; + reg_bounds_sync(ret_reg); + break; + case BPF_FUNC_get_smp_processor_id: + ret_reg->umax_value = nr_cpu_ids - 1; + ret_reg->u32_max_value = nr_cpu_ids - 1; + ret_reg->smax_value = nr_cpu_ids - 1; + ret_reg->s32_max_value = nr_cpu_ids - 1; + ret_reg->umin_value = 0; + ret_reg->u32_min_value = 0; + ret_reg->smin_value = 0; + ret_reg->s32_min_value = 0; + reg_bounds_sync(ret_reg); + break; + } +} + +static int +record_func_map(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta, + int func_id, int insn_idx) +{ + struct bpf_insn_aux_data *aux = &env->insn_aux_data[insn_idx]; + struct bpf_map *map = meta->map_ptr; + + if (func_id != BPF_FUNC_tail_call && + func_id != BPF_FUNC_map_lookup_elem && + func_id != BPF_FUNC_map_update_elem && + func_id != BPF_FUNC_map_delete_elem && + func_id != BPF_FUNC_map_push_elem && + func_id != BPF_FUNC_map_pop_elem && + func_id != BPF_FUNC_map_peek_elem && + func_id != BPF_FUNC_for_each_map_elem && + func_id != BPF_FUNC_redirect_map && + func_id != BPF_FUNC_map_lookup_percpu_elem) + return 0; + + if (map == NULL) { + verbose(env, "kernel subsystem misconfigured verifier\n"); + return -EINVAL; + } + + /* In case of read-only, some additional restrictions + * need to be applied in order to prevent altering the + * state of the map from program side. + */ + if ((map->map_flags & BPF_F_RDONLY_PROG) && + (func_id == BPF_FUNC_map_delete_elem || + func_id == BPF_FUNC_map_update_elem || + func_id == BPF_FUNC_map_push_elem || + func_id == BPF_FUNC_map_pop_elem)) { + verbose(env, "write into map forbidden\n"); + return -EACCES; + } + + if (!BPF_MAP_PTR(aux->map_ptr_state)) + bpf_map_ptr_store(aux, meta->map_ptr, + !meta->map_ptr->bypass_spec_v1); + else if (BPF_MAP_PTR(aux->map_ptr_state) != meta->map_ptr) + bpf_map_ptr_store(aux, BPF_MAP_PTR_POISON, + !meta->map_ptr->bypass_spec_v1); + return 0; +} + +static int +record_func_key(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta, + int func_id, int insn_idx) +{ + struct bpf_insn_aux_data *aux = &env->insn_aux_data[insn_idx]; + struct bpf_reg_state *regs = cur_regs(env), *reg; + struct bpf_map *map = meta->map_ptr; + u64 val, max; + int err; + + if (func_id != BPF_FUNC_tail_call) + return 0; + if (!map || map->map_type != BPF_MAP_TYPE_PROG_ARRAY) { + verbose(env, "kernel subsystem misconfigured verifier\n"); + return -EINVAL; + } + + reg = ®s[BPF_REG_3]; + val = reg->var_off.value; + max = map->max_entries; + + if (!(register_is_const(reg) && val < max)) { + bpf_map_key_store(aux, BPF_MAP_KEY_POISON); + return 0; + } + + err = mark_chain_precision(env, BPF_REG_3); + if (err) + return err; + if (bpf_map_key_unseen(aux)) + bpf_map_key_store(aux, val); + else if (!bpf_map_key_poisoned(aux) && + bpf_map_key_immediate(aux) != val) + bpf_map_key_store(aux, BPF_MAP_KEY_POISON); + return 0; +} + +static int check_reference_leak(struct bpf_verifier_env *env) +{ + struct bpf_func_state *state = cur_func(env); + bool refs_lingering = false; + int i; + + if (state->frameno && !state->in_callback_fn) + return 0; + + for (i = 0; i < state->acquired_refs; i++) { + if (state->in_callback_fn && state->refs[i].callback_ref != state->frameno) + continue; + verbose(env, "Unreleased reference id=%d alloc_insn=%d\n", + state->refs[i].id, state->refs[i].insn_idx); + refs_lingering = true; + } + return refs_lingering ? -EINVAL : 0; +} + +static int check_bpf_snprintf_call(struct bpf_verifier_env *env, + struct bpf_reg_state *regs) +{ + struct bpf_reg_state *fmt_reg = ®s[BPF_REG_3]; + struct bpf_reg_state *data_len_reg = ®s[BPF_REG_5]; + struct bpf_map *fmt_map = fmt_reg->map_ptr; + struct bpf_bprintf_data data = {}; + int err, fmt_map_off, num_args; + u64 fmt_addr; + char *fmt; + + /* data must be an array of u64 */ + if (data_len_reg->var_off.value % 8) + return -EINVAL; + num_args = data_len_reg->var_off.value / 8; + + /* fmt being ARG_PTR_TO_CONST_STR guarantees that var_off is const + * and map_direct_value_addr is set. + */ + fmt_map_off = fmt_reg->off + fmt_reg->var_off.value; + err = fmt_map->ops->map_direct_value_addr(fmt_map, &fmt_addr, + fmt_map_off); + if (err) { + verbose(env, "verifier bug\n"); + return -EFAULT; + } + fmt = (char *)(long)fmt_addr + fmt_map_off; + + /* We are also guaranteed that fmt+fmt_map_off is NULL terminated, we + * can focus on validating the format specifiers. + */ + err = bpf_bprintf_prepare(fmt, UINT_MAX, NULL, num_args, &data); + if (err < 0) + verbose(env, "Invalid format string\n"); + + return err; +} + +static int check_get_func_ip(struct bpf_verifier_env *env) +{ + enum bpf_prog_type type = resolve_prog_type(env->prog); + int func_id = BPF_FUNC_get_func_ip; + + if (type == BPF_PROG_TYPE_TRACING) { + if (!bpf_prog_has_trampoline(env->prog)) { + verbose(env, "func %s#%d supported only for fentry/fexit/fmod_ret programs\n", + func_id_name(func_id), func_id); + return -ENOTSUPP; + } + return 0; + } else if (type == BPF_PROG_TYPE_KPROBE) { + return 0; + } + + verbose(env, "func %s#%d not supported for program type %d\n", + func_id_name(func_id), func_id, type); + return -ENOTSUPP; +} + +static struct bpf_insn_aux_data *cur_aux(struct bpf_verifier_env *env) +{ + return &env->insn_aux_data[env->insn_idx]; +} + +static bool loop_flag_is_zero(struct bpf_verifier_env *env) +{ + struct bpf_reg_state *regs = cur_regs(env); + struct bpf_reg_state *reg = ®s[BPF_REG_4]; + bool reg_is_null = register_is_null(reg); + + if (reg_is_null) + mark_chain_precision(env, BPF_REG_4); + + return reg_is_null; +} + +static void update_loop_inline_state(struct bpf_verifier_env *env, u32 subprogno) +{ + struct bpf_loop_inline_state *state = &cur_aux(env)->loop_inline_state; + + if (!state->initialized) { + state->initialized = 1; + state->fit_for_inline = loop_flag_is_zero(env); + state->callback_subprogno = subprogno; + return; + } + + if (!state->fit_for_inline) + return; + + state->fit_for_inline = (loop_flag_is_zero(env) && + state->callback_subprogno == subprogno); +} + +static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn, + int *insn_idx_p) +{ + enum bpf_prog_type prog_type = resolve_prog_type(env->prog); + const struct bpf_func_proto *fn = NULL; + enum bpf_return_type ret_type; + enum bpf_type_flag ret_flag; + struct bpf_reg_state *regs; + struct bpf_call_arg_meta meta; + int insn_idx = *insn_idx_p; + bool changes_data; + int i, err, func_id; + + /* find function prototype */ + func_id = insn->imm; + if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) { + verbose(env, "invalid func %s#%d\n", func_id_name(func_id), + func_id); + return -EINVAL; + } + + if (env->ops->get_func_proto) + fn = env->ops->get_func_proto(func_id, env->prog); + if (!fn) { + verbose(env, "unknown func %s#%d\n", func_id_name(func_id), + func_id); + return -EINVAL; + } + + /* eBPF programs must be GPL compatible to use GPL-ed functions */ + if (!env->prog->gpl_compatible && fn->gpl_only) { + verbose(env, "cannot call GPL-restricted function from non-GPL compatible program\n"); + return -EINVAL; + } + + if (fn->allowed && !fn->allowed(env->prog)) { + verbose(env, "helper call is not allowed in probe\n"); + return -EINVAL; + } + + if (!env->prog->aux->sleepable && fn->might_sleep) { + verbose(env, "helper call might sleep in a non-sleepable prog\n"); + return -EINVAL; + } + + /* With LD_ABS/IND some JITs save/restore skb from r1. */ + changes_data = bpf_helper_changes_pkt_data(fn->func); + if (changes_data && fn->arg1_type != ARG_PTR_TO_CTX) { + verbose(env, "kernel subsystem misconfigured func %s#%d: r1 != ctx\n", + func_id_name(func_id), func_id); + return -EINVAL; + } + + memset(&meta, 0, sizeof(meta)); + meta.pkt_access = fn->pkt_access; + + err = check_func_proto(fn, func_id); + if (err) { + verbose(env, "kernel subsystem misconfigured func %s#%d\n", + func_id_name(func_id), func_id); + return err; + } + + if (env->cur_state->active_rcu_lock) { + if (fn->might_sleep) { + verbose(env, "sleepable helper %s#%d in rcu_read_lock region\n", + func_id_name(func_id), func_id); + return -EINVAL; + } + + if (env->prog->aux->sleepable && is_storage_get_function(func_id)) + env->insn_aux_data[insn_idx].storage_get_func_atomic = true; + } + + meta.func_id = func_id; + /* check args */ + for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++) { + err = check_func_arg(env, i, &meta, fn, insn_idx); + if (err) + return err; + } + + err = record_func_map(env, &meta, func_id, insn_idx); + if (err) + return err; + + err = record_func_key(env, &meta, func_id, insn_idx); + if (err) + return err; + + /* Mark slots with STACK_MISC in case of raw mode, stack offset + * is inferred from register state. + */ + for (i = 0; i < meta.access_size; i++) { + err = check_mem_access(env, insn_idx, meta.regno, i, BPF_B, + BPF_WRITE, -1, false, false); + if (err) + return err; + } + + regs = cur_regs(env); + + if (meta.release_regno) { + err = -EINVAL; + /* This can only be set for PTR_TO_STACK, as CONST_PTR_TO_DYNPTR cannot + * be released by any dynptr helper. Hence, unmark_stack_slots_dynptr + * is safe to do directly. + */ + if (arg_type_is_dynptr(fn->arg_type[meta.release_regno - BPF_REG_1])) { + if (regs[meta.release_regno].type == CONST_PTR_TO_DYNPTR) { + verbose(env, "verifier internal error: CONST_PTR_TO_DYNPTR cannot be released\n"); + return -EFAULT; + } + err = unmark_stack_slots_dynptr(env, ®s[meta.release_regno]); + } else if (meta.ref_obj_id) { + err = release_reference(env, meta.ref_obj_id); + } else if (register_is_null(®s[meta.release_regno])) { + /* meta.ref_obj_id can only be 0 if register that is meant to be + * released is NULL, which must be > R0. + */ + err = 0; + } + if (err) { + verbose(env, "func %s#%d reference has not been acquired before\n", + func_id_name(func_id), func_id); + return err; + } + } + + switch (func_id) { + case BPF_FUNC_tail_call: + err = check_reference_leak(env); + if (err) { + verbose(env, "tail_call would lead to reference leak\n"); + return err; + } + break; + case BPF_FUNC_get_local_storage: + /* check that flags argument in get_local_storage(map, flags) is 0, + * this is required because get_local_storage() can't return an error. + */ + if (!register_is_null(®s[BPF_REG_2])) { + verbose(env, "get_local_storage() doesn't support non-zero flags\n"); + return -EINVAL; + } + break; + case BPF_FUNC_for_each_map_elem: + err = push_callback_call(env, insn, insn_idx, meta.subprogno, + set_map_elem_callback_state); + break; + case BPF_FUNC_timer_set_callback: + err = push_callback_call(env, insn, insn_idx, meta.subprogno, + set_timer_callback_state); + break; + case BPF_FUNC_find_vma: + err = push_callback_call(env, insn, insn_idx, meta.subprogno, + set_find_vma_callback_state); + break; + case BPF_FUNC_snprintf: + err = check_bpf_snprintf_call(env, regs); + break; + case BPF_FUNC_loop: + update_loop_inline_state(env, meta.subprogno); + /* Verifier relies on R1 value to determine if bpf_loop() iteration + * is finished, thus mark it precise. + */ + err = mark_chain_precision(env, BPF_REG_1); + if (err) + return err; + if (cur_func(env)->callback_depth < regs[BPF_REG_1].umax_value) { + err = push_callback_call(env, insn, insn_idx, meta.subprogno, + set_loop_callback_state); + } else { + cur_func(env)->callback_depth = 0; + if (env->log.level & BPF_LOG_LEVEL2) + verbose(env, "frame%d bpf_loop iteration limit reached\n", + env->cur_state->curframe); + } + break; + case BPF_FUNC_dynptr_from_mem: + if (regs[BPF_REG_1].type != PTR_TO_MAP_VALUE) { + verbose(env, "Unsupported reg type %s for bpf_dynptr_from_mem data\n", + reg_type_str(env, regs[BPF_REG_1].type)); + return -EACCES; + } + break; + case BPF_FUNC_set_retval: + if (prog_type == BPF_PROG_TYPE_LSM && + env->prog->expected_attach_type == BPF_LSM_CGROUP) { + if (!env->prog->aux->attach_func_proto->type) { + /* Make sure programs that attach to void + * hooks don't try to modify return value. + */ + verbose(env, "BPF_LSM_CGROUP that attach to void LSM hooks can't modify return value!\n"); + return -EINVAL; + } + } + break; + case BPF_FUNC_dynptr_data: + { + struct bpf_reg_state *reg; + int id, ref_obj_id; + + reg = get_dynptr_arg_reg(env, fn, regs); + if (!reg) + return -EFAULT; + + + if (meta.dynptr_id) { + verbose(env, "verifier internal error: meta.dynptr_id already set\n"); + return -EFAULT; + } + if (meta.ref_obj_id) { + verbose(env, "verifier internal error: meta.ref_obj_id already set\n"); + return -EFAULT; + } + + id = dynptr_id(env, reg); + if (id < 0) { + verbose(env, "verifier internal error: failed to obtain dynptr id\n"); + return id; + } + + ref_obj_id = dynptr_ref_obj_id(env, reg); + if (ref_obj_id < 0) { + verbose(env, "verifier internal error: failed to obtain dynptr ref_obj_id\n"); + return ref_obj_id; + } + + meta.dynptr_id = id; + meta.ref_obj_id = ref_obj_id; + + break; + } + case BPF_FUNC_dynptr_write: + { + enum bpf_dynptr_type dynptr_type; + struct bpf_reg_state *reg; + + reg = get_dynptr_arg_reg(env, fn, regs); + if (!reg) + return -EFAULT; + + dynptr_type = dynptr_get_type(env, reg); + if (dynptr_type == BPF_DYNPTR_TYPE_INVALID) + return -EFAULT; + + if (dynptr_type == BPF_DYNPTR_TYPE_SKB) + /* this will trigger clear_all_pkt_pointers(), which will + * invalidate all dynptr slices associated with the skb + */ + changes_data = true; + + break; + } + case BPF_FUNC_user_ringbuf_drain: + err = push_callback_call(env, insn, insn_idx, meta.subprogno, + set_user_ringbuf_callback_state); + break; + } + + if (err) + return err; + + /* reset caller saved regs */ + for (i = 0; i < CALLER_SAVED_REGS; i++) { + mark_reg_not_init(env, regs, caller_saved[i]); + check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK); + } + + /* helper call returns 64-bit value. */ + regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG; + + /* update return register (already marked as written above) */ + ret_type = fn->ret_type; + ret_flag = type_flag(ret_type); + + switch (base_type(ret_type)) { + case RET_INTEGER: + /* sets type to SCALAR_VALUE */ + mark_reg_unknown(env, regs, BPF_REG_0); + break; + case RET_VOID: + regs[BPF_REG_0].type = NOT_INIT; + break; + case RET_PTR_TO_MAP_VALUE: + /* There is no offset yet applied, variable or fixed */ + mark_reg_known_zero(env, regs, BPF_REG_0); + /* remember map_ptr, so that check_map_access() + * can check 'value_size' boundary of memory access + * to map element returned from bpf_map_lookup_elem() + */ + if (meta.map_ptr == NULL) { + verbose(env, + "kernel subsystem misconfigured verifier\n"); + return -EINVAL; + } + regs[BPF_REG_0].map_ptr = meta.map_ptr; + regs[BPF_REG_0].map_uid = meta.map_uid; + regs[BPF_REG_0].type = PTR_TO_MAP_VALUE | ret_flag; + if (!type_may_be_null(ret_type) && + btf_record_has_field(meta.map_ptr->record, BPF_SPIN_LOCK)) { + regs[BPF_REG_0].id = ++env->id_gen; + } + break; + case RET_PTR_TO_SOCKET: + mark_reg_known_zero(env, regs, BPF_REG_0); + regs[BPF_REG_0].type = PTR_TO_SOCKET | ret_flag; + break; + case RET_PTR_TO_SOCK_COMMON: + mark_reg_known_zero(env, regs, BPF_REG_0); + regs[BPF_REG_0].type = PTR_TO_SOCK_COMMON | ret_flag; + break; + case RET_PTR_TO_TCP_SOCK: + mark_reg_known_zero(env, regs, BPF_REG_0); + regs[BPF_REG_0].type = PTR_TO_TCP_SOCK | ret_flag; + break; + case RET_PTR_TO_MEM: + mark_reg_known_zero(env, regs, BPF_REG_0); + regs[BPF_REG_0].type = PTR_TO_MEM | ret_flag; + regs[BPF_REG_0].mem_size = meta.mem_size; + break; + case RET_PTR_TO_MEM_OR_BTF_ID: + { + const struct btf_type *t; + + mark_reg_known_zero(env, regs, BPF_REG_0); + t = btf_type_skip_modifiers(meta.ret_btf, meta.ret_btf_id, NULL); + if (!btf_type_is_struct(t)) { + u32 tsize; + const struct btf_type *ret; + const char *tname; + + /* resolve the type size of ksym. */ + ret = btf_resolve_size(meta.ret_btf, t, &tsize); + if (IS_ERR(ret)) { + tname = btf_name_by_offset(meta.ret_btf, t->name_off); + verbose(env, "unable to resolve the size of type '%s': %ld\n", + tname, PTR_ERR(ret)); + return -EINVAL; + } + regs[BPF_REG_0].type = PTR_TO_MEM | ret_flag; + regs[BPF_REG_0].mem_size = tsize; + } else { + /* MEM_RDONLY may be carried from ret_flag, but it + * doesn't apply on PTR_TO_BTF_ID. Fold it, otherwise + * it will confuse the check of PTR_TO_BTF_ID in + * check_mem_access(). + */ + ret_flag &= ~MEM_RDONLY; + + regs[BPF_REG_0].type = PTR_TO_BTF_ID | ret_flag; + regs[BPF_REG_0].btf = meta.ret_btf; + regs[BPF_REG_0].btf_id = meta.ret_btf_id; + } + break; + } + case RET_PTR_TO_BTF_ID: + { + struct btf *ret_btf; + int ret_btf_id; + + mark_reg_known_zero(env, regs, BPF_REG_0); + regs[BPF_REG_0].type = PTR_TO_BTF_ID | ret_flag; + if (func_id == BPF_FUNC_kptr_xchg) { + ret_btf = meta.kptr_field->kptr.btf; + ret_btf_id = meta.kptr_field->kptr.btf_id; + if (!btf_is_kernel(ret_btf)) + regs[BPF_REG_0].type |= MEM_ALLOC; + } else { + if (fn->ret_btf_id == BPF_PTR_POISON) { + verbose(env, "verifier internal error:"); + verbose(env, "func %s has non-overwritten BPF_PTR_POISON return type\n", + func_id_name(func_id)); + return -EINVAL; + } + ret_btf = btf_vmlinux; + ret_btf_id = *fn->ret_btf_id; + } + if (ret_btf_id == 0) { + verbose(env, "invalid return type %u of func %s#%d\n", + base_type(ret_type), func_id_name(func_id), + func_id); + return -EINVAL; + } + regs[BPF_REG_0].btf = ret_btf; + regs[BPF_REG_0].btf_id = ret_btf_id; + break; + } + default: + verbose(env, "unknown return type %u of func %s#%d\n", + base_type(ret_type), func_id_name(func_id), func_id); + return -EINVAL; + } + + if (type_may_be_null(regs[BPF_REG_0].type)) + regs[BPF_REG_0].id = ++env->id_gen; + + if (helper_multiple_ref_obj_use(func_id, meta.map_ptr)) { + verbose(env, "verifier internal error: func %s#%d sets ref_obj_id more than once\n", + func_id_name(func_id), func_id); + return -EFAULT; + } + + if (is_dynptr_ref_function(func_id)) + regs[BPF_REG_0].dynptr_id = meta.dynptr_id; + + if (is_ptr_cast_function(func_id) || is_dynptr_ref_function(func_id)) { + /* For release_reference() */ + regs[BPF_REG_0].ref_obj_id = meta.ref_obj_id; + } else if (is_acquire_function(func_id, meta.map_ptr)) { + int id = acquire_reference_state(env, insn_idx); + + if (id < 0) + return id; + /* For mark_ptr_or_null_reg() */ + regs[BPF_REG_0].id = id; + /* For release_reference() */ + regs[BPF_REG_0].ref_obj_id = id; + } + + do_refine_retval_range(regs, fn->ret_type, func_id, &meta); + + err = check_map_func_compatibility(env, meta.map_ptr, func_id); + if (err) + return err; + + if ((func_id == BPF_FUNC_get_stack || + func_id == BPF_FUNC_get_task_stack) && + !env->prog->has_callchain_buf) { + const char *err_str; + +#ifdef CONFIG_PERF_EVENTS + err = get_callchain_buffers(sysctl_perf_event_max_stack); + err_str = "cannot get callchain buffer for func %s#%d\n"; +#else + err = -ENOTSUPP; + err_str = "func %s#%d not supported without CONFIG_PERF_EVENTS\n"; +#endif + if (err) { + verbose(env, err_str, func_id_name(func_id), func_id); + return err; + } + + env->prog->has_callchain_buf = true; + } + + if (func_id == BPF_FUNC_get_stackid || func_id == BPF_FUNC_get_stack) + env->prog->call_get_stack = true; + + if (func_id == BPF_FUNC_get_func_ip) { + if (check_get_func_ip(env)) + return -ENOTSUPP; + env->prog->call_get_func_ip = true; + } + + if (changes_data) + clear_all_pkt_pointers(env); + return 0; +} + +/* mark_btf_func_reg_size() is used when the reg size is determined by + * the BTF func_proto's return value size and argument. + */ +static void mark_btf_func_reg_size(struct bpf_verifier_env *env, u32 regno, + size_t reg_size) +{ + struct bpf_reg_state *reg = &cur_regs(env)[regno]; + + if (regno == BPF_REG_0) { + /* Function return value */ + reg->live |= REG_LIVE_WRITTEN; + reg->subreg_def = reg_size == sizeof(u64) ? + DEF_NOT_SUBREG : env->insn_idx + 1; + } else { + /* Function argument */ + if (reg_size == sizeof(u64)) { + mark_insn_zext(env, reg); + mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64); + } else { + mark_reg_read(env, reg, reg->parent, REG_LIVE_READ32); + } + } +} + +static bool is_kfunc_acquire(struct bpf_kfunc_call_arg_meta *meta) +{ + return meta->kfunc_flags & KF_ACQUIRE; +} + +static bool is_kfunc_release(struct bpf_kfunc_call_arg_meta *meta) +{ + return meta->kfunc_flags & KF_RELEASE; +} + +static bool is_kfunc_trusted_args(struct bpf_kfunc_call_arg_meta *meta) +{ + return (meta->kfunc_flags & KF_TRUSTED_ARGS) || is_kfunc_release(meta); +} + +static bool is_kfunc_sleepable(struct bpf_kfunc_call_arg_meta *meta) +{ + return meta->kfunc_flags & KF_SLEEPABLE; +} + +static bool is_kfunc_destructive(struct bpf_kfunc_call_arg_meta *meta) +{ + return meta->kfunc_flags & KF_DESTRUCTIVE; +} + +static bool is_kfunc_rcu(struct bpf_kfunc_call_arg_meta *meta) +{ + return meta->kfunc_flags & KF_RCU; +} + +static bool __kfunc_param_match_suffix(const struct btf *btf, + const struct btf_param *arg, + const char *suffix) +{ + int suffix_len = strlen(suffix), len; + const char *param_name; + + /* In the future, this can be ported to use BTF tagging */ + param_name = btf_name_by_offset(btf, arg->name_off); + if (str_is_empty(param_name)) + return false; + len = strlen(param_name); + if (len < suffix_len) + return false; + param_name += len - suffix_len; + return !strncmp(param_name, suffix, suffix_len); +} + +static bool is_kfunc_arg_mem_size(const struct btf *btf, + const struct btf_param *arg, + const struct bpf_reg_state *reg) +{ + const struct btf_type *t; + + t = btf_type_skip_modifiers(btf, arg->type, NULL); + if (!btf_type_is_scalar(t) || reg->type != SCALAR_VALUE) + return false; + + return __kfunc_param_match_suffix(btf, arg, "__sz"); +} + +static bool is_kfunc_arg_const_mem_size(const struct btf *btf, + const struct btf_param *arg, + const struct bpf_reg_state *reg) +{ + const struct btf_type *t; + + t = btf_type_skip_modifiers(btf, arg->type, NULL); + if (!btf_type_is_scalar(t) || reg->type != SCALAR_VALUE) + return false; + + return __kfunc_param_match_suffix(btf, arg, "__szk"); +} + +static bool is_kfunc_arg_optional(const struct btf *btf, const struct btf_param *arg) +{ + return __kfunc_param_match_suffix(btf, arg, "__opt"); +} + +static bool is_kfunc_arg_constant(const struct btf *btf, const struct btf_param *arg) +{ + return __kfunc_param_match_suffix(btf, arg, "__k"); +} + +static bool is_kfunc_arg_ignore(const struct btf *btf, const struct btf_param *arg) +{ + return __kfunc_param_match_suffix(btf, arg, "__ign"); +} + +static bool is_kfunc_arg_alloc_obj(const struct btf *btf, const struct btf_param *arg) +{ + return __kfunc_param_match_suffix(btf, arg, "__alloc"); +} + +static bool is_kfunc_arg_uninit(const struct btf *btf, const struct btf_param *arg) +{ + return __kfunc_param_match_suffix(btf, arg, "__uninit"); +} + +static bool is_kfunc_arg_refcounted_kptr(const struct btf *btf, const struct btf_param *arg) +{ + return __kfunc_param_match_suffix(btf, arg, "__refcounted_kptr"); +} + +static bool is_kfunc_arg_scalar_with_name(const struct btf *btf, + const struct btf_param *arg, + const char *name) +{ + int len, target_len = strlen(name); + const char *param_name; + + param_name = btf_name_by_offset(btf, arg->name_off); + if (str_is_empty(param_name)) + return false; + len = strlen(param_name); + if (len != target_len) + return false; + if (strcmp(param_name, name)) + return false; + + return true; +} + +enum { + KF_ARG_DYNPTR_ID, + KF_ARG_LIST_HEAD_ID, + KF_ARG_LIST_NODE_ID, + KF_ARG_RB_ROOT_ID, + KF_ARG_RB_NODE_ID, +}; + +BTF_ID_LIST(kf_arg_btf_ids) +BTF_ID(struct, bpf_dynptr_kern) +BTF_ID(struct, bpf_list_head) +BTF_ID(struct, bpf_list_node) +BTF_ID(struct, bpf_rb_root) +BTF_ID(struct, bpf_rb_node) + +static bool __is_kfunc_ptr_arg_type(const struct btf *btf, + const struct btf_param *arg, int type) +{ + const struct btf_type *t; + u32 res_id; + + t = btf_type_skip_modifiers(btf, arg->type, NULL); + if (!t) + return false; + if (!btf_type_is_ptr(t)) + return false; + t = btf_type_skip_modifiers(btf, t->type, &res_id); + if (!t) + return false; + return btf_types_are_same(btf, res_id, btf_vmlinux, kf_arg_btf_ids[type]); +} + +static bool is_kfunc_arg_dynptr(const struct btf *btf, const struct btf_param *arg) +{ + return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_DYNPTR_ID); +} + +static bool is_kfunc_arg_list_head(const struct btf *btf, const struct btf_param *arg) +{ + return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_LIST_HEAD_ID); +} + +static bool is_kfunc_arg_list_node(const struct btf *btf, const struct btf_param *arg) +{ + return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_LIST_NODE_ID); +} + +static bool is_kfunc_arg_rbtree_root(const struct btf *btf, const struct btf_param *arg) +{ + return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_RB_ROOT_ID); +} + +static bool is_kfunc_arg_rbtree_node(const struct btf *btf, const struct btf_param *arg) +{ + return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_RB_NODE_ID); +} + +static bool is_kfunc_arg_callback(struct bpf_verifier_env *env, const struct btf *btf, + const struct btf_param *arg) +{ + const struct btf_type *t; + + t = btf_type_resolve_func_ptr(btf, arg->type, NULL); + if (!t) + return false; + + return true; +} + +/* Returns true if struct is composed of scalars, 4 levels of nesting allowed */ +static bool __btf_type_is_scalar_struct(struct bpf_verifier_env *env, + const struct btf *btf, + const struct btf_type *t, int rec) +{ + const struct btf_type *member_type; + const struct btf_member *member; + u32 i; + + if (!btf_type_is_struct(t)) + return false; + + for_each_member(i, t, member) { + const struct btf_array *array; + + member_type = btf_type_skip_modifiers(btf, member->type, NULL); + if (btf_type_is_struct(member_type)) { + if (rec >= 3) { + verbose(env, "max struct nesting depth exceeded\n"); + return false; + } + if (!__btf_type_is_scalar_struct(env, btf, member_type, rec + 1)) + return false; + continue; + } + if (btf_type_is_array(member_type)) { + array = btf_array(member_type); + if (!array->nelems) + return false; + member_type = btf_type_skip_modifiers(btf, array->type, NULL); + if (!btf_type_is_scalar(member_type)) + return false; + continue; + } + if (!btf_type_is_scalar(member_type)) + return false; + } + return true; +} + +enum kfunc_ptr_arg_type { + KF_ARG_PTR_TO_CTX, + KF_ARG_PTR_TO_ALLOC_BTF_ID, /* Allocated object */ + KF_ARG_PTR_TO_REFCOUNTED_KPTR, /* Refcounted local kptr */ + KF_ARG_PTR_TO_DYNPTR, + KF_ARG_PTR_TO_ITER, + KF_ARG_PTR_TO_LIST_HEAD, + KF_ARG_PTR_TO_LIST_NODE, + KF_ARG_PTR_TO_BTF_ID, /* Also covers reg2btf_ids conversions */ + KF_ARG_PTR_TO_MEM, + KF_ARG_PTR_TO_MEM_SIZE, /* Size derived from next argument, skip it */ + KF_ARG_PTR_TO_CALLBACK, + KF_ARG_PTR_TO_RB_ROOT, + KF_ARG_PTR_TO_RB_NODE, +}; + +enum special_kfunc_type { + KF_bpf_obj_new_impl, + KF_bpf_obj_drop_impl, + KF_bpf_refcount_acquire_impl, + KF_bpf_list_push_front_impl, + KF_bpf_list_push_back_impl, + KF_bpf_list_pop_front, + KF_bpf_list_pop_back, + KF_bpf_cast_to_kern_ctx, + KF_bpf_rdonly_cast, + KF_bpf_rcu_read_lock, + KF_bpf_rcu_read_unlock, + KF_bpf_rbtree_remove, + KF_bpf_rbtree_add_impl, + KF_bpf_rbtree_first, + KF_bpf_dynptr_from_skb, + KF_bpf_dynptr_from_xdp, + KF_bpf_dynptr_slice, + KF_bpf_dynptr_slice_rdwr, + KF_bpf_dynptr_clone, +}; + +BTF_SET_START(special_kfunc_set) +BTF_ID(func, bpf_obj_new_impl) +BTF_ID(func, bpf_obj_drop_impl) +BTF_ID(func, bpf_refcount_acquire_impl) +BTF_ID(func, bpf_list_push_front_impl) +BTF_ID(func, bpf_list_push_back_impl) +BTF_ID(func, bpf_list_pop_front) +BTF_ID(func, bpf_list_pop_back) +BTF_ID(func, bpf_cast_to_kern_ctx) +BTF_ID(func, bpf_rdonly_cast) +BTF_ID(func, bpf_rbtree_remove) +BTF_ID(func, bpf_rbtree_add_impl) +BTF_ID(func, bpf_rbtree_first) +BTF_ID(func, bpf_dynptr_from_skb) +BTF_ID(func, bpf_dynptr_from_xdp) +BTF_ID(func, bpf_dynptr_slice) +BTF_ID(func, bpf_dynptr_slice_rdwr) +BTF_ID(func, bpf_dynptr_clone) +BTF_SET_END(special_kfunc_set) + +BTF_ID_LIST(special_kfunc_list) +BTF_ID(func, bpf_obj_new_impl) +BTF_ID(func, bpf_obj_drop_impl) +BTF_ID(func, bpf_refcount_acquire_impl) +BTF_ID(func, bpf_list_push_front_impl) +BTF_ID(func, bpf_list_push_back_impl) +BTF_ID(func, bpf_list_pop_front) +BTF_ID(func, bpf_list_pop_back) +BTF_ID(func, bpf_cast_to_kern_ctx) +BTF_ID(func, bpf_rdonly_cast) +BTF_ID(func, bpf_rcu_read_lock) +BTF_ID(func, bpf_rcu_read_unlock) +BTF_ID(func, bpf_rbtree_remove) +BTF_ID(func, bpf_rbtree_add_impl) +BTF_ID(func, bpf_rbtree_first) +BTF_ID(func, bpf_dynptr_from_skb) +BTF_ID(func, bpf_dynptr_from_xdp) +BTF_ID(func, bpf_dynptr_slice) +BTF_ID(func, bpf_dynptr_slice_rdwr) +BTF_ID(func, bpf_dynptr_clone) + +static bool is_kfunc_ret_null(struct bpf_kfunc_call_arg_meta *meta) +{ + if (meta->func_id == special_kfunc_list[KF_bpf_refcount_acquire_impl] && + meta->arg_owning_ref) { + return false; + } + + return meta->kfunc_flags & KF_RET_NULL; +} + +static bool is_kfunc_bpf_rcu_read_lock(struct bpf_kfunc_call_arg_meta *meta) +{ + return meta->func_id == special_kfunc_list[KF_bpf_rcu_read_lock]; +} + +static bool is_kfunc_bpf_rcu_read_unlock(struct bpf_kfunc_call_arg_meta *meta) +{ + return meta->func_id == special_kfunc_list[KF_bpf_rcu_read_unlock]; +} + +static enum kfunc_ptr_arg_type +get_kfunc_ptr_arg_type(struct bpf_verifier_env *env, + struct bpf_kfunc_call_arg_meta *meta, + const struct btf_type *t, const struct btf_type *ref_t, + const char *ref_tname, const struct btf_param *args, + int argno, int nargs) +{ + u32 regno = argno + 1; + struct bpf_reg_state *regs = cur_regs(env); + struct bpf_reg_state *reg = ®s[regno]; + bool arg_mem_size = false; + + if (meta->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx]) + return KF_ARG_PTR_TO_CTX; + + /* In this function, we verify the kfunc's BTF as per the argument type, + * leaving the rest of the verification with respect to the register + * type to our caller. When a set of conditions hold in the BTF type of + * arguments, we resolve it to a known kfunc_ptr_arg_type. + */ + if (btf_get_prog_ctx_type(&env->log, meta->btf, t, resolve_prog_type(env->prog), argno)) + return KF_ARG_PTR_TO_CTX; + + if (is_kfunc_arg_alloc_obj(meta->btf, &args[argno])) + return KF_ARG_PTR_TO_ALLOC_BTF_ID; + + if (is_kfunc_arg_refcounted_kptr(meta->btf, &args[argno])) + return KF_ARG_PTR_TO_REFCOUNTED_KPTR; + + if (is_kfunc_arg_dynptr(meta->btf, &args[argno])) + return KF_ARG_PTR_TO_DYNPTR; + + if (is_kfunc_arg_iter(meta, argno)) + return KF_ARG_PTR_TO_ITER; + + if (is_kfunc_arg_list_head(meta->btf, &args[argno])) + return KF_ARG_PTR_TO_LIST_HEAD; + + if (is_kfunc_arg_list_node(meta->btf, &args[argno])) + return KF_ARG_PTR_TO_LIST_NODE; + + if (is_kfunc_arg_rbtree_root(meta->btf, &args[argno])) + return KF_ARG_PTR_TO_RB_ROOT; + + if (is_kfunc_arg_rbtree_node(meta->btf, &args[argno])) + return KF_ARG_PTR_TO_RB_NODE; + + if ((base_type(reg->type) == PTR_TO_BTF_ID || reg2btf_ids[base_type(reg->type)])) { + if (!btf_type_is_struct(ref_t)) { + verbose(env, "kernel function %s args#%d pointer type %s %s is not supported\n", + meta->func_name, argno, btf_type_str(ref_t), ref_tname); + return -EINVAL; + } + return KF_ARG_PTR_TO_BTF_ID; + } + + if (is_kfunc_arg_callback(env, meta->btf, &args[argno])) + return KF_ARG_PTR_TO_CALLBACK; + + + if (argno + 1 < nargs && + (is_kfunc_arg_mem_size(meta->btf, &args[argno + 1], ®s[regno + 1]) || + is_kfunc_arg_const_mem_size(meta->btf, &args[argno + 1], ®s[regno + 1]))) + arg_mem_size = true; + + /* This is the catch all argument type of register types supported by + * check_helper_mem_access. However, we only allow when argument type is + * pointer to scalar, or struct composed (recursively) of scalars. When + * arg_mem_size is true, the pointer can be void *. + */ + if (!btf_type_is_scalar(ref_t) && !__btf_type_is_scalar_struct(env, meta->btf, ref_t, 0) && + (arg_mem_size ? !btf_type_is_void(ref_t) : 1)) { + verbose(env, "arg#%d pointer type %s %s must point to %sscalar, or struct with scalar\n", + argno, btf_type_str(ref_t), ref_tname, arg_mem_size ? "void, " : ""); + return -EINVAL; + } + return arg_mem_size ? KF_ARG_PTR_TO_MEM_SIZE : KF_ARG_PTR_TO_MEM; +} + +static int process_kf_arg_ptr_to_btf_id(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, + const struct btf_type *ref_t, + const char *ref_tname, u32 ref_id, + struct bpf_kfunc_call_arg_meta *meta, + int argno) +{ + const struct btf_type *reg_ref_t; + bool strict_type_match = false; + const struct btf *reg_btf; + const char *reg_ref_tname; + u32 reg_ref_id; + + if (base_type(reg->type) == PTR_TO_BTF_ID) { + reg_btf = reg->btf; + reg_ref_id = reg->btf_id; + } else { + reg_btf = btf_vmlinux; + reg_ref_id = *reg2btf_ids[base_type(reg->type)]; + } + + /* Enforce strict type matching for calls to kfuncs that are acquiring + * or releasing a reference, or are no-cast aliases. We do _not_ + * enforce strict matching for plain KF_TRUSTED_ARGS kfuncs by default, + * as we want to enable BPF programs to pass types that are bitwise + * equivalent without forcing them to explicitly cast with something + * like bpf_cast_to_kern_ctx(). + * + * For example, say we had a type like the following: + * + * struct bpf_cpumask { + * cpumask_t cpumask; + * refcount_t usage; + * }; + * + * Note that as specified in <linux/cpumask.h>, cpumask_t is typedef'ed + * to a struct cpumask, so it would be safe to pass a struct + * bpf_cpumask * to a kfunc expecting a struct cpumask *. + * + * The philosophy here is similar to how we allow scalars of different + * types to be passed to kfuncs as long as the size is the same. The + * only difference here is that we're simply allowing + * btf_struct_ids_match() to walk the struct at the 0th offset, and + * resolve types. + */ + if (is_kfunc_acquire(meta) || + (is_kfunc_release(meta) && reg->ref_obj_id) || + btf_type_ids_nocast_alias(&env->log, reg_btf, reg_ref_id, meta->btf, ref_id)) + strict_type_match = true; + + WARN_ON_ONCE(is_kfunc_trusted_args(meta) && reg->off); + + reg_ref_t = btf_type_skip_modifiers(reg_btf, reg_ref_id, ®_ref_id); + reg_ref_tname = btf_name_by_offset(reg_btf, reg_ref_t->name_off); + if (!btf_struct_ids_match(&env->log, reg_btf, reg_ref_id, reg->off, meta->btf, ref_id, strict_type_match)) { + verbose(env, "kernel function %s args#%d expected pointer to %s %s but R%d has a pointer to %s %s\n", + meta->func_name, argno, btf_type_str(ref_t), ref_tname, argno + 1, + btf_type_str(reg_ref_t), reg_ref_tname); + return -EINVAL; + } + return 0; +} + +static int ref_set_non_owning(struct bpf_verifier_env *env, struct bpf_reg_state *reg) +{ + struct bpf_verifier_state *state = env->cur_state; + struct btf_record *rec = reg_btf_record(reg); + + if (!state->active_lock.ptr) { + verbose(env, "verifier internal error: ref_set_non_owning w/o active lock\n"); + return -EFAULT; + } + + if (type_flag(reg->type) & NON_OWN_REF) { + verbose(env, "verifier internal error: NON_OWN_REF already set\n"); + return -EFAULT; + } + + reg->type |= NON_OWN_REF; + if (rec->refcount_off >= 0) + reg->type |= MEM_RCU; + + return 0; +} + +static int ref_convert_owning_non_owning(struct bpf_verifier_env *env, u32 ref_obj_id) +{ + struct bpf_func_state *state, *unused; + struct bpf_reg_state *reg; + int i; + + state = cur_func(env); + + if (!ref_obj_id) { + verbose(env, "verifier internal error: ref_obj_id is zero for " + "owning -> non-owning conversion\n"); + return -EFAULT; + } + + for (i = 0; i < state->acquired_refs; i++) { + if (state->refs[i].id != ref_obj_id) + continue; + + /* Clear ref_obj_id here so release_reference doesn't clobber + * the whole reg + */ + bpf_for_each_reg_in_vstate(env->cur_state, unused, reg, ({ + if (reg->ref_obj_id == ref_obj_id) { + reg->ref_obj_id = 0; + ref_set_non_owning(env, reg); + } + })); + return 0; + } + + verbose(env, "verifier internal error: ref state missing for ref_obj_id\n"); + return -EFAULT; +} + +/* Implementation details: + * + * Each register points to some region of memory, which we define as an + * allocation. Each allocation may embed a bpf_spin_lock which protects any + * special BPF objects (bpf_list_head, bpf_rb_root, etc.) part of the same + * allocation. The lock and the data it protects are colocated in the same + * memory region. + * + * Hence, everytime a register holds a pointer value pointing to such + * allocation, the verifier preserves a unique reg->id for it. + * + * The verifier remembers the lock 'ptr' and the lock 'id' whenever + * bpf_spin_lock is called. + * + * To enable this, lock state in the verifier captures two values: + * active_lock.ptr = Register's type specific pointer + * active_lock.id = A unique ID for each register pointer value + * + * Currently, PTR_TO_MAP_VALUE and PTR_TO_BTF_ID | MEM_ALLOC are the two + * supported register types. + * + * The active_lock.ptr in case of map values is the reg->map_ptr, and in case of + * allocated objects is the reg->btf pointer. + * + * The active_lock.id is non-unique for maps supporting direct_value_addr, as we + * can establish the provenance of the map value statically for each distinct + * lookup into such maps. They always contain a single map value hence unique + * IDs for each pseudo load pessimizes the algorithm and rejects valid programs. + * + * So, in case of global variables, they use array maps with max_entries = 1, + * hence their active_lock.ptr becomes map_ptr and id = 0 (since they all point + * into the same map value as max_entries is 1, as described above). + * + * In case of inner map lookups, the inner map pointer has same map_ptr as the + * outer map pointer (in verifier context), but each lookup into an inner map + * assigns a fresh reg->id to the lookup, so while lookups into distinct inner + * maps from the same outer map share the same map_ptr as active_lock.ptr, they + * will get different reg->id assigned to each lookup, hence different + * active_lock.id. + * + * In case of allocated objects, active_lock.ptr is the reg->btf, and the + * reg->id is a unique ID preserved after the NULL pointer check on the pointer + * returned from bpf_obj_new. Each allocation receives a new reg->id. + */ +static int check_reg_allocation_locked(struct bpf_verifier_env *env, struct bpf_reg_state *reg) +{ + void *ptr; + u32 id; + + switch ((int)reg->type) { + case PTR_TO_MAP_VALUE: + ptr = reg->map_ptr; + break; + case PTR_TO_BTF_ID | MEM_ALLOC: + ptr = reg->btf; + break; + default: + verbose(env, "verifier internal error: unknown reg type for lock check\n"); + return -EFAULT; + } + id = reg->id; + + if (!env->cur_state->active_lock.ptr) + return -EINVAL; + if (env->cur_state->active_lock.ptr != ptr || + env->cur_state->active_lock.id != id) { + verbose(env, "held lock and object are not in the same allocation\n"); + return -EINVAL; + } + return 0; +} + +static bool is_bpf_list_api_kfunc(u32 btf_id) +{ + return btf_id == special_kfunc_list[KF_bpf_list_push_front_impl] || + btf_id == special_kfunc_list[KF_bpf_list_push_back_impl] || + btf_id == special_kfunc_list[KF_bpf_list_pop_front] || + btf_id == special_kfunc_list[KF_bpf_list_pop_back]; +} + +static bool is_bpf_rbtree_api_kfunc(u32 btf_id) +{ + return btf_id == special_kfunc_list[KF_bpf_rbtree_add_impl] || + btf_id == special_kfunc_list[KF_bpf_rbtree_remove] || + btf_id == special_kfunc_list[KF_bpf_rbtree_first]; +} + +static bool is_bpf_graph_api_kfunc(u32 btf_id) +{ + return is_bpf_list_api_kfunc(btf_id) || is_bpf_rbtree_api_kfunc(btf_id) || + btf_id == special_kfunc_list[KF_bpf_refcount_acquire_impl]; +} + +static bool is_sync_callback_calling_kfunc(u32 btf_id) +{ + return btf_id == special_kfunc_list[KF_bpf_rbtree_add_impl]; +} + +static bool is_rbtree_lock_required_kfunc(u32 btf_id) +{ + return is_bpf_rbtree_api_kfunc(btf_id); +} + +static bool check_kfunc_is_graph_root_api(struct bpf_verifier_env *env, + enum btf_field_type head_field_type, + u32 kfunc_btf_id) +{ + bool ret; + + switch (head_field_type) { + case BPF_LIST_HEAD: + ret = is_bpf_list_api_kfunc(kfunc_btf_id); + break; + case BPF_RB_ROOT: + ret = is_bpf_rbtree_api_kfunc(kfunc_btf_id); + break; + default: + verbose(env, "verifier internal error: unexpected graph root argument type %s\n", + btf_field_type_name(head_field_type)); + return false; + } + + if (!ret) + verbose(env, "verifier internal error: %s head arg for unknown kfunc\n", + btf_field_type_name(head_field_type)); + return ret; +} + +static bool check_kfunc_is_graph_node_api(struct bpf_verifier_env *env, + enum btf_field_type node_field_type, + u32 kfunc_btf_id) +{ + bool ret; + + switch (node_field_type) { + case BPF_LIST_NODE: + ret = (kfunc_btf_id == special_kfunc_list[KF_bpf_list_push_front_impl] || + kfunc_btf_id == special_kfunc_list[KF_bpf_list_push_back_impl]); + break; + case BPF_RB_NODE: + ret = (kfunc_btf_id == special_kfunc_list[KF_bpf_rbtree_remove] || + kfunc_btf_id == special_kfunc_list[KF_bpf_rbtree_add_impl]); + break; + default: + verbose(env, "verifier internal error: unexpected graph node argument type %s\n", + btf_field_type_name(node_field_type)); + return false; + } + + if (!ret) + verbose(env, "verifier internal error: %s node arg for unknown kfunc\n", + btf_field_type_name(node_field_type)); + return ret; +} + +static int +__process_kf_arg_ptr_to_graph_root(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, u32 regno, + struct bpf_kfunc_call_arg_meta *meta, + enum btf_field_type head_field_type, + struct btf_field **head_field) +{ + const char *head_type_name; + struct btf_field *field; + struct btf_record *rec; + u32 head_off; + + if (meta->btf != btf_vmlinux) { + verbose(env, "verifier internal error: unexpected btf mismatch in kfunc call\n"); + return -EFAULT; + } + + if (!check_kfunc_is_graph_root_api(env, head_field_type, meta->func_id)) + return -EFAULT; + + head_type_name = btf_field_type_name(head_field_type); + if (!tnum_is_const(reg->var_off)) { + verbose(env, + "R%d doesn't have constant offset. %s has to be at the constant offset\n", + regno, head_type_name); + return -EINVAL; + } + + rec = reg_btf_record(reg); + head_off = reg->off + reg->var_off.value; + field = btf_record_find(rec, head_off, head_field_type); + if (!field) { + verbose(env, "%s not found at offset=%u\n", head_type_name, head_off); + return -EINVAL; + } + + /* All functions require bpf_list_head to be protected using a bpf_spin_lock */ + if (check_reg_allocation_locked(env, reg)) { + verbose(env, "bpf_spin_lock at off=%d must be held for %s\n", + rec->spin_lock_off, head_type_name); + return -EINVAL; + } + + if (*head_field) { + verbose(env, "verifier internal error: repeating %s arg\n", head_type_name); + return -EFAULT; + } + *head_field = field; + return 0; +} + +static int process_kf_arg_ptr_to_list_head(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, u32 regno, + struct bpf_kfunc_call_arg_meta *meta) +{ + return __process_kf_arg_ptr_to_graph_root(env, reg, regno, meta, BPF_LIST_HEAD, + &meta->arg_list_head.field); +} + +static int process_kf_arg_ptr_to_rbtree_root(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, u32 regno, + struct bpf_kfunc_call_arg_meta *meta) +{ + return __process_kf_arg_ptr_to_graph_root(env, reg, regno, meta, BPF_RB_ROOT, + &meta->arg_rbtree_root.field); +} + +static int +__process_kf_arg_ptr_to_graph_node(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, u32 regno, + struct bpf_kfunc_call_arg_meta *meta, + enum btf_field_type head_field_type, + enum btf_field_type node_field_type, + struct btf_field **node_field) +{ + const char *node_type_name; + const struct btf_type *et, *t; + struct btf_field *field; + u32 node_off; + + if (meta->btf != btf_vmlinux) { + verbose(env, "verifier internal error: unexpected btf mismatch in kfunc call\n"); + return -EFAULT; + } + + if (!check_kfunc_is_graph_node_api(env, node_field_type, meta->func_id)) + return -EFAULT; + + node_type_name = btf_field_type_name(node_field_type); + if (!tnum_is_const(reg->var_off)) { + verbose(env, + "R%d doesn't have constant offset. %s has to be at the constant offset\n", + regno, node_type_name); + return -EINVAL; + } + + node_off = reg->off + reg->var_off.value; + field = reg_find_field_offset(reg, node_off, node_field_type); + if (!field || field->offset != node_off) { + verbose(env, "%s not found at offset=%u\n", node_type_name, node_off); + return -EINVAL; + } + + field = *node_field; + + et = btf_type_by_id(field->graph_root.btf, field->graph_root.value_btf_id); + t = btf_type_by_id(reg->btf, reg->btf_id); + if (!btf_struct_ids_match(&env->log, reg->btf, reg->btf_id, 0, field->graph_root.btf, + field->graph_root.value_btf_id, true)) { + verbose(env, "operation on %s expects arg#1 %s at offset=%d " + "in struct %s, but arg is at offset=%d in struct %s\n", + btf_field_type_name(head_field_type), + btf_field_type_name(node_field_type), + field->graph_root.node_offset, + btf_name_by_offset(field->graph_root.btf, et->name_off), + node_off, btf_name_by_offset(reg->btf, t->name_off)); + return -EINVAL; + } + meta->arg_btf = reg->btf; + meta->arg_btf_id = reg->btf_id; + + if (node_off != field->graph_root.node_offset) { + verbose(env, "arg#1 offset=%d, but expected %s at offset=%d in struct %s\n", + node_off, btf_field_type_name(node_field_type), + field->graph_root.node_offset, + btf_name_by_offset(field->graph_root.btf, et->name_off)); + return -EINVAL; + } + + return 0; +} + +static int process_kf_arg_ptr_to_list_node(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, u32 regno, + struct bpf_kfunc_call_arg_meta *meta) +{ + return __process_kf_arg_ptr_to_graph_node(env, reg, regno, meta, + BPF_LIST_HEAD, BPF_LIST_NODE, + &meta->arg_list_head.field); +} + +static int process_kf_arg_ptr_to_rbtree_node(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, u32 regno, + struct bpf_kfunc_call_arg_meta *meta) +{ + return __process_kf_arg_ptr_to_graph_node(env, reg, regno, meta, + BPF_RB_ROOT, BPF_RB_NODE, + &meta->arg_rbtree_root.field); +} + +static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_arg_meta *meta, + int insn_idx) +{ + const char *func_name = meta->func_name, *ref_tname; + const struct btf *btf = meta->btf; + const struct btf_param *args; + struct btf_record *rec; + u32 i, nargs; + int ret; + + args = (const struct btf_param *)(meta->func_proto + 1); + nargs = btf_type_vlen(meta->func_proto); + if (nargs > MAX_BPF_FUNC_REG_ARGS) { + verbose(env, "Function %s has %d > %d args\n", func_name, nargs, + MAX_BPF_FUNC_REG_ARGS); + return -EINVAL; + } + + /* Check that BTF function arguments match actual types that the + * verifier sees. + */ + for (i = 0; i < nargs; i++) { + struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[i + 1]; + const struct btf_type *t, *ref_t, *resolve_ret; + enum bpf_arg_type arg_type = ARG_DONTCARE; + u32 regno = i + 1, ref_id, type_size; + bool is_ret_buf_sz = false; + int kf_arg_type; + + t = btf_type_skip_modifiers(btf, args[i].type, NULL); + + if (is_kfunc_arg_ignore(btf, &args[i])) + continue; + + if (btf_type_is_scalar(t)) { + if (reg->type != SCALAR_VALUE) { + verbose(env, "R%d is not a scalar\n", regno); + return -EINVAL; + } + + if (is_kfunc_arg_constant(meta->btf, &args[i])) { + if (meta->arg_constant.found) { + verbose(env, "verifier internal error: only one constant argument permitted\n"); + return -EFAULT; + } + if (!tnum_is_const(reg->var_off)) { + verbose(env, "R%d must be a known constant\n", regno); + return -EINVAL; + } + ret = mark_chain_precision(env, regno); + if (ret < 0) + return ret; + meta->arg_constant.found = true; + meta->arg_constant.value = reg->var_off.value; + } else if (is_kfunc_arg_scalar_with_name(btf, &args[i], "rdonly_buf_size")) { + meta->r0_rdonly = true; + is_ret_buf_sz = true; + } else if (is_kfunc_arg_scalar_with_name(btf, &args[i], "rdwr_buf_size")) { + is_ret_buf_sz = true; + } + + if (is_ret_buf_sz) { + if (meta->r0_size) { + verbose(env, "2 or more rdonly/rdwr_buf_size parameters for kfunc"); + return -EINVAL; + } + + if (!tnum_is_const(reg->var_off)) { + verbose(env, "R%d is not a const\n", regno); + return -EINVAL; + } + + meta->r0_size = reg->var_off.value; + ret = mark_chain_precision(env, regno); + if (ret) + return ret; + } + continue; + } + + if (!btf_type_is_ptr(t)) { + verbose(env, "Unrecognized arg#%d type %s\n", i, btf_type_str(t)); + return -EINVAL; + } + + if ((is_kfunc_trusted_args(meta) || is_kfunc_rcu(meta)) && + (register_is_null(reg) || type_may_be_null(reg->type))) { + verbose(env, "Possibly NULL pointer passed to trusted arg%d\n", i); + return -EACCES; + } + + if (reg->ref_obj_id) { + if (is_kfunc_release(meta) && meta->ref_obj_id) { + verbose(env, "verifier internal error: more than one arg with ref_obj_id R%d %u %u\n", + regno, reg->ref_obj_id, + meta->ref_obj_id); + return -EFAULT; + } + meta->ref_obj_id = reg->ref_obj_id; + if (is_kfunc_release(meta)) + meta->release_regno = regno; + } + + ref_t = btf_type_skip_modifiers(btf, t->type, &ref_id); + ref_tname = btf_name_by_offset(btf, ref_t->name_off); + + kf_arg_type = get_kfunc_ptr_arg_type(env, meta, t, ref_t, ref_tname, args, i, nargs); + if (kf_arg_type < 0) + return kf_arg_type; + + switch (kf_arg_type) { + case KF_ARG_PTR_TO_ALLOC_BTF_ID: + case KF_ARG_PTR_TO_BTF_ID: + if (!is_kfunc_trusted_args(meta) && !is_kfunc_rcu(meta)) + break; + + if (!is_trusted_reg(reg)) { + if (!is_kfunc_rcu(meta)) { + verbose(env, "R%d must be referenced or trusted\n", regno); + return -EINVAL; + } + if (!is_rcu_reg(reg)) { + verbose(env, "R%d must be a rcu pointer\n", regno); + return -EINVAL; + } + } + + fallthrough; + case KF_ARG_PTR_TO_CTX: + /* Trusted arguments have the same offset checks as release arguments */ + arg_type |= OBJ_RELEASE; + break; + case KF_ARG_PTR_TO_DYNPTR: + case KF_ARG_PTR_TO_ITER: + case KF_ARG_PTR_TO_LIST_HEAD: + case KF_ARG_PTR_TO_LIST_NODE: + case KF_ARG_PTR_TO_RB_ROOT: + case KF_ARG_PTR_TO_RB_NODE: + case KF_ARG_PTR_TO_MEM: + case KF_ARG_PTR_TO_MEM_SIZE: + case KF_ARG_PTR_TO_CALLBACK: + case KF_ARG_PTR_TO_REFCOUNTED_KPTR: + /* Trusted by default */ + break; + default: + WARN_ON_ONCE(1); + return -EFAULT; + } + + if (is_kfunc_release(meta) && reg->ref_obj_id) + arg_type |= OBJ_RELEASE; + ret = check_func_arg_reg_off(env, reg, regno, arg_type); + if (ret < 0) + return ret; + + switch (kf_arg_type) { + case KF_ARG_PTR_TO_CTX: + if (reg->type != PTR_TO_CTX) { + verbose(env, "arg#%d expected pointer to ctx, but got %s\n", i, btf_type_str(t)); + return -EINVAL; + } + + if (meta->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx]) { + ret = get_kern_ctx_btf_id(&env->log, resolve_prog_type(env->prog)); + if (ret < 0) + return -EINVAL; + meta->ret_btf_id = ret; + } + break; + case KF_ARG_PTR_TO_ALLOC_BTF_ID: + if (reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) { + verbose(env, "arg#%d expected pointer to allocated object\n", i); + return -EINVAL; + } + if (!reg->ref_obj_id) { + verbose(env, "allocated object must be referenced\n"); + return -EINVAL; + } + if (meta->btf == btf_vmlinux && + meta->func_id == special_kfunc_list[KF_bpf_obj_drop_impl]) { + meta->arg_btf = reg->btf; + meta->arg_btf_id = reg->btf_id; + } + break; + case KF_ARG_PTR_TO_DYNPTR: + { + enum bpf_arg_type dynptr_arg_type = ARG_PTR_TO_DYNPTR; + int clone_ref_obj_id = 0; + + if (reg->type != PTR_TO_STACK && + reg->type != CONST_PTR_TO_DYNPTR) { + verbose(env, "arg#%d expected pointer to stack or dynptr_ptr\n", i); + return -EINVAL; + } + + if (reg->type == CONST_PTR_TO_DYNPTR) + dynptr_arg_type |= MEM_RDONLY; + + if (is_kfunc_arg_uninit(btf, &args[i])) + dynptr_arg_type |= MEM_UNINIT; + + if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_from_skb]) { + dynptr_arg_type |= DYNPTR_TYPE_SKB; + } else if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_from_xdp]) { + dynptr_arg_type |= DYNPTR_TYPE_XDP; + } else if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_clone] && + (dynptr_arg_type & MEM_UNINIT)) { + enum bpf_dynptr_type parent_type = meta->initialized_dynptr.type; + + if (parent_type == BPF_DYNPTR_TYPE_INVALID) { + verbose(env, "verifier internal error: no dynptr type for parent of clone\n"); + return -EFAULT; + } + + dynptr_arg_type |= (unsigned int)get_dynptr_type_flag(parent_type); + clone_ref_obj_id = meta->initialized_dynptr.ref_obj_id; + if (dynptr_type_refcounted(parent_type) && !clone_ref_obj_id) { + verbose(env, "verifier internal error: missing ref obj id for parent of clone\n"); + return -EFAULT; + } + } + + ret = process_dynptr_func(env, regno, insn_idx, dynptr_arg_type, clone_ref_obj_id); + if (ret < 0) + return ret; + + if (!(dynptr_arg_type & MEM_UNINIT)) { + int id = dynptr_id(env, reg); + + if (id < 0) { + verbose(env, "verifier internal error: failed to obtain dynptr id\n"); + return id; + } + meta->initialized_dynptr.id = id; + meta->initialized_dynptr.type = dynptr_get_type(env, reg); + meta->initialized_dynptr.ref_obj_id = dynptr_ref_obj_id(env, reg); + } + + break; + } + case KF_ARG_PTR_TO_ITER: + ret = process_iter_arg(env, regno, insn_idx, meta); + if (ret < 0) + return ret; + break; + case KF_ARG_PTR_TO_LIST_HEAD: + if (reg->type != PTR_TO_MAP_VALUE && + reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) { + verbose(env, "arg#%d expected pointer to map value or allocated object\n", i); + return -EINVAL; + } + if (reg->type == (PTR_TO_BTF_ID | MEM_ALLOC) && !reg->ref_obj_id) { + verbose(env, "allocated object must be referenced\n"); + return -EINVAL; + } + ret = process_kf_arg_ptr_to_list_head(env, reg, regno, meta); + if (ret < 0) + return ret; + break; + case KF_ARG_PTR_TO_RB_ROOT: + if (reg->type != PTR_TO_MAP_VALUE && + reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) { + verbose(env, "arg#%d expected pointer to map value or allocated object\n", i); + return -EINVAL; + } + if (reg->type == (PTR_TO_BTF_ID | MEM_ALLOC) && !reg->ref_obj_id) { + verbose(env, "allocated object must be referenced\n"); + return -EINVAL; + } + ret = process_kf_arg_ptr_to_rbtree_root(env, reg, regno, meta); + if (ret < 0) + return ret; + break; + case KF_ARG_PTR_TO_LIST_NODE: + if (reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) { + verbose(env, "arg#%d expected pointer to allocated object\n", i); + return -EINVAL; + } + if (!reg->ref_obj_id) { + verbose(env, "allocated object must be referenced\n"); + return -EINVAL; + } + ret = process_kf_arg_ptr_to_list_node(env, reg, regno, meta); + if (ret < 0) + return ret; + break; + case KF_ARG_PTR_TO_RB_NODE: + if (meta->func_id == special_kfunc_list[KF_bpf_rbtree_remove]) { + if (!type_is_non_owning_ref(reg->type) || reg->ref_obj_id) { + verbose(env, "rbtree_remove node input must be non-owning ref\n"); + return -EINVAL; + } + if (in_rbtree_lock_required_cb(env)) { + verbose(env, "rbtree_remove not allowed in rbtree cb\n"); + return -EINVAL; + } + } else { + if (reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) { + verbose(env, "arg#%d expected pointer to allocated object\n", i); + return -EINVAL; + } + if (!reg->ref_obj_id) { + verbose(env, "allocated object must be referenced\n"); + return -EINVAL; + } + } + + ret = process_kf_arg_ptr_to_rbtree_node(env, reg, regno, meta); + if (ret < 0) + return ret; + break; + case KF_ARG_PTR_TO_BTF_ID: + /* Only base_type is checked, further checks are done here */ + if ((base_type(reg->type) != PTR_TO_BTF_ID || + (bpf_type_has_unsafe_modifiers(reg->type) && !is_rcu_reg(reg))) && + !reg2btf_ids[base_type(reg->type)]) { + verbose(env, "arg#%d is %s ", i, reg_type_str(env, reg->type)); + verbose(env, "expected %s or socket\n", + reg_type_str(env, base_type(reg->type) | + (type_flag(reg->type) & BPF_REG_TRUSTED_MODIFIERS))); + return -EINVAL; + } + ret = process_kf_arg_ptr_to_btf_id(env, reg, ref_t, ref_tname, ref_id, meta, i); + if (ret < 0) + return ret; + break; + case KF_ARG_PTR_TO_MEM: + resolve_ret = btf_resolve_size(btf, ref_t, &type_size); + if (IS_ERR(resolve_ret)) { + verbose(env, "arg#%d reference type('%s %s') size cannot be determined: %ld\n", + i, btf_type_str(ref_t), ref_tname, PTR_ERR(resolve_ret)); + return -EINVAL; + } + ret = check_mem_reg(env, reg, regno, type_size); + if (ret < 0) + return ret; + break; + case KF_ARG_PTR_TO_MEM_SIZE: + { + struct bpf_reg_state *buff_reg = ®s[regno]; + const struct btf_param *buff_arg = &args[i]; + struct bpf_reg_state *size_reg = ®s[regno + 1]; + const struct btf_param *size_arg = &args[i + 1]; + + if (!register_is_null(buff_reg) || !is_kfunc_arg_optional(meta->btf, buff_arg)) { + ret = check_kfunc_mem_size_reg(env, size_reg, regno + 1); + if (ret < 0) { + verbose(env, "arg#%d arg#%d memory, len pair leads to invalid memory access\n", i, i + 1); + return ret; + } + } + + if (is_kfunc_arg_const_mem_size(meta->btf, size_arg, size_reg)) { + if (meta->arg_constant.found) { + verbose(env, "verifier internal error: only one constant argument permitted\n"); + return -EFAULT; + } + if (!tnum_is_const(size_reg->var_off)) { + verbose(env, "R%d must be a known constant\n", regno + 1); + return -EINVAL; + } + meta->arg_constant.found = true; + meta->arg_constant.value = size_reg->var_off.value; + } + + /* Skip next '__sz' or '__szk' argument */ + i++; + break; + } + case KF_ARG_PTR_TO_CALLBACK: + if (reg->type != PTR_TO_FUNC) { + verbose(env, "arg%d expected pointer to func\n", i); + return -EINVAL; + } + meta->subprogno = reg->subprogno; + break; + case KF_ARG_PTR_TO_REFCOUNTED_KPTR: + if (!type_is_ptr_alloc_obj(reg->type)) { + verbose(env, "arg#%d is neither owning or non-owning ref\n", i); + return -EINVAL; + } + if (!type_is_non_owning_ref(reg->type)) + meta->arg_owning_ref = true; + + rec = reg_btf_record(reg); + if (!rec) { + verbose(env, "verifier internal error: Couldn't find btf_record\n"); + return -EFAULT; + } + + if (rec->refcount_off < 0) { + verbose(env, "arg#%d doesn't point to a type with bpf_refcount field\n", i); + return -EINVAL; + } + + meta->arg_btf = reg->btf; + meta->arg_btf_id = reg->btf_id; + break; + } + } + + if (is_kfunc_release(meta) && !meta->release_regno) { + verbose(env, "release kernel function %s expects refcounted PTR_TO_BTF_ID\n", + func_name); + return -EINVAL; + } + + return 0; +} + +static int fetch_kfunc_meta(struct bpf_verifier_env *env, + struct bpf_insn *insn, + struct bpf_kfunc_call_arg_meta *meta, + const char **kfunc_name) +{ + const struct btf_type *func, *func_proto; + u32 func_id, *kfunc_flags; + const char *func_name; + struct btf *desc_btf; + + if (kfunc_name) + *kfunc_name = NULL; + + if (!insn->imm) + return -EINVAL; + + desc_btf = find_kfunc_desc_btf(env, insn->off); + if (IS_ERR(desc_btf)) + return PTR_ERR(desc_btf); + + func_id = insn->imm; + func = btf_type_by_id(desc_btf, func_id); + func_name = btf_name_by_offset(desc_btf, func->name_off); + if (kfunc_name) + *kfunc_name = func_name; + func_proto = btf_type_by_id(desc_btf, func->type); + + kfunc_flags = btf_kfunc_id_set_contains(desc_btf, func_id, env->prog); + if (!kfunc_flags) { + return -EACCES; + } + + memset(meta, 0, sizeof(*meta)); + meta->btf = desc_btf; + meta->func_id = func_id; + meta->kfunc_flags = *kfunc_flags; + meta->func_proto = func_proto; + meta->func_name = func_name; + + return 0; +} + +static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, + int *insn_idx_p) +{ + const struct btf_type *t, *ptr_type; + u32 i, nargs, ptr_type_id, release_ref_obj_id; + struct bpf_reg_state *regs = cur_regs(env); + const char *func_name, *ptr_type_name; + bool sleepable, rcu_lock, rcu_unlock; + struct bpf_kfunc_call_arg_meta meta; + struct bpf_insn_aux_data *insn_aux; + int err, insn_idx = *insn_idx_p; + const struct btf_param *args; + const struct btf_type *ret_t; + struct btf *desc_btf; + + /* skip for now, but return error when we find this in fixup_kfunc_call */ + if (!insn->imm) + return 0; + + err = fetch_kfunc_meta(env, insn, &meta, &func_name); + if (err == -EACCES && func_name) + verbose(env, "calling kernel function %s is not allowed\n", func_name); + if (err) + return err; + desc_btf = meta.btf; + insn_aux = &env->insn_aux_data[insn_idx]; + + insn_aux->is_iter_next = is_iter_next_kfunc(&meta); + + if (is_kfunc_destructive(&meta) && !capable(CAP_SYS_BOOT)) { + verbose(env, "destructive kfunc calls require CAP_SYS_BOOT capability\n"); + return -EACCES; + } + + sleepable = is_kfunc_sleepable(&meta); + if (sleepable && !env->prog->aux->sleepable) { + verbose(env, "program must be sleepable to call sleepable kfunc %s\n", func_name); + return -EACCES; + } + + /* Check the arguments */ + err = check_kfunc_args(env, &meta, insn_idx); + if (err < 0) + return err; + + if (meta.func_id == special_kfunc_list[KF_bpf_rbtree_add_impl]) { + err = push_callback_call(env, insn, insn_idx, meta.subprogno, + set_rbtree_add_callback_state); + if (err) { + verbose(env, "kfunc %s#%d failed callback verification\n", + func_name, meta.func_id); + return err; + } + } + + rcu_lock = is_kfunc_bpf_rcu_read_lock(&meta); + rcu_unlock = is_kfunc_bpf_rcu_read_unlock(&meta); + + if (env->cur_state->active_rcu_lock) { + struct bpf_func_state *state; + struct bpf_reg_state *reg; + + if (in_rbtree_lock_required_cb(env) && (rcu_lock || rcu_unlock)) { + verbose(env, "Calling bpf_rcu_read_{lock,unlock} in unnecessary rbtree callback\n"); + return -EACCES; + } + + if (rcu_lock) { + verbose(env, "nested rcu read lock (kernel function %s)\n", func_name); + return -EINVAL; + } else if (rcu_unlock) { + bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({ + if (reg->type & MEM_RCU) { + reg->type &= ~(MEM_RCU | PTR_MAYBE_NULL); + reg->type |= PTR_UNTRUSTED; + } + })); + env->cur_state->active_rcu_lock = false; + } else if (sleepable) { + verbose(env, "kernel func %s is sleepable within rcu_read_lock region\n", func_name); + return -EACCES; + } + } else if (rcu_lock) { + env->cur_state->active_rcu_lock = true; + } else if (rcu_unlock) { + verbose(env, "unmatched rcu read unlock (kernel function %s)\n", func_name); + return -EINVAL; + } + + /* In case of release function, we get register number of refcounted + * PTR_TO_BTF_ID in bpf_kfunc_arg_meta, do the release now. + */ + if (meta.release_regno) { + err = release_reference(env, regs[meta.release_regno].ref_obj_id); + if (err) { + verbose(env, "kfunc %s#%d reference has not been acquired before\n", + func_name, meta.func_id); + return err; + } + } + + if (meta.func_id == special_kfunc_list[KF_bpf_list_push_front_impl] || + meta.func_id == special_kfunc_list[KF_bpf_list_push_back_impl] || + meta.func_id == special_kfunc_list[KF_bpf_rbtree_add_impl]) { + release_ref_obj_id = regs[BPF_REG_2].ref_obj_id; + insn_aux->insert_off = regs[BPF_REG_2].off; + insn_aux->kptr_struct_meta = btf_find_struct_meta(meta.arg_btf, meta.arg_btf_id); + err = ref_convert_owning_non_owning(env, release_ref_obj_id); + if (err) { + verbose(env, "kfunc %s#%d conversion of owning ref to non-owning failed\n", + func_name, meta.func_id); + return err; + } + + err = release_reference(env, release_ref_obj_id); + if (err) { + verbose(env, "kfunc %s#%d reference has not been acquired before\n", + func_name, meta.func_id); + return err; + } + } + + for (i = 0; i < CALLER_SAVED_REGS; i++) + mark_reg_not_init(env, regs, caller_saved[i]); + + /* Check return type */ + t = btf_type_skip_modifiers(desc_btf, meta.func_proto->type, NULL); + + if (is_kfunc_acquire(&meta) && !btf_type_is_struct_ptr(meta.btf, t)) { + /* Only exception is bpf_obj_new_impl */ + if (meta.btf != btf_vmlinux || + (meta.func_id != special_kfunc_list[KF_bpf_obj_new_impl] && + meta.func_id != special_kfunc_list[KF_bpf_refcount_acquire_impl])) { + verbose(env, "acquire kernel function does not return PTR_TO_BTF_ID\n"); + return -EINVAL; + } + } + + if (btf_type_is_scalar(t)) { + mark_reg_unknown(env, regs, BPF_REG_0); + mark_btf_func_reg_size(env, BPF_REG_0, t->size); + } else if (btf_type_is_ptr(t)) { + ptr_type = btf_type_skip_modifiers(desc_btf, t->type, &ptr_type_id); + + if (meta.btf == btf_vmlinux && btf_id_set_contains(&special_kfunc_set, meta.func_id)) { + if (meta.func_id == special_kfunc_list[KF_bpf_obj_new_impl]) { + struct btf *ret_btf; + u32 ret_btf_id; + + if (unlikely(!bpf_global_ma_set)) + return -ENOMEM; + + if (((u64)(u32)meta.arg_constant.value) != meta.arg_constant.value) { + verbose(env, "local type ID argument must be in range [0, U32_MAX]\n"); + return -EINVAL; + } + + ret_btf = env->prog->aux->btf; + ret_btf_id = meta.arg_constant.value; + + /* This may be NULL due to user not supplying a BTF */ + if (!ret_btf) { + verbose(env, "bpf_obj_new requires prog BTF\n"); + return -EINVAL; + } + + ret_t = btf_type_by_id(ret_btf, ret_btf_id); + if (!ret_t || !__btf_type_is_struct(ret_t)) { + verbose(env, "bpf_obj_new type ID argument must be of a struct\n"); + return -EINVAL; + } + + mark_reg_known_zero(env, regs, BPF_REG_0); + regs[BPF_REG_0].type = PTR_TO_BTF_ID | MEM_ALLOC; + regs[BPF_REG_0].btf = ret_btf; + regs[BPF_REG_0].btf_id = ret_btf_id; + + insn_aux->obj_new_size = ret_t->size; + insn_aux->kptr_struct_meta = + btf_find_struct_meta(ret_btf, ret_btf_id); + } else if (meta.func_id == special_kfunc_list[KF_bpf_refcount_acquire_impl]) { + mark_reg_known_zero(env, regs, BPF_REG_0); + regs[BPF_REG_0].type = PTR_TO_BTF_ID | MEM_ALLOC; + regs[BPF_REG_0].btf = meta.arg_btf; + regs[BPF_REG_0].btf_id = meta.arg_btf_id; + + insn_aux->kptr_struct_meta = + btf_find_struct_meta(meta.arg_btf, + meta.arg_btf_id); + } else if (meta.func_id == special_kfunc_list[KF_bpf_list_pop_front] || + meta.func_id == special_kfunc_list[KF_bpf_list_pop_back]) { + struct btf_field *field = meta.arg_list_head.field; + + mark_reg_graph_node(regs, BPF_REG_0, &field->graph_root); + } else if (meta.func_id == special_kfunc_list[KF_bpf_rbtree_remove] || + meta.func_id == special_kfunc_list[KF_bpf_rbtree_first]) { + struct btf_field *field = meta.arg_rbtree_root.field; + + mark_reg_graph_node(regs, BPF_REG_0, &field->graph_root); + } else if (meta.func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx]) { + mark_reg_known_zero(env, regs, BPF_REG_0); + regs[BPF_REG_0].type = PTR_TO_BTF_ID | PTR_TRUSTED; + regs[BPF_REG_0].btf = desc_btf; + regs[BPF_REG_0].btf_id = meta.ret_btf_id; + } else if (meta.func_id == special_kfunc_list[KF_bpf_rdonly_cast]) { + ret_t = btf_type_by_id(desc_btf, meta.arg_constant.value); + if (!ret_t || !btf_type_is_struct(ret_t)) { + verbose(env, + "kfunc bpf_rdonly_cast type ID argument must be of a struct\n"); + return -EINVAL; + } + + mark_reg_known_zero(env, regs, BPF_REG_0); + regs[BPF_REG_0].type = PTR_TO_BTF_ID | PTR_UNTRUSTED; + regs[BPF_REG_0].btf = desc_btf; + regs[BPF_REG_0].btf_id = meta.arg_constant.value; + } else if (meta.func_id == special_kfunc_list[KF_bpf_dynptr_slice] || + meta.func_id == special_kfunc_list[KF_bpf_dynptr_slice_rdwr]) { + enum bpf_type_flag type_flag = get_dynptr_type_flag(meta.initialized_dynptr.type); + + mark_reg_known_zero(env, regs, BPF_REG_0); + + if (!meta.arg_constant.found) { + verbose(env, "verifier internal error: bpf_dynptr_slice(_rdwr) no constant size\n"); + return -EFAULT; + } + + regs[BPF_REG_0].mem_size = meta.arg_constant.value; + + /* PTR_MAYBE_NULL will be added when is_kfunc_ret_null is checked */ + regs[BPF_REG_0].type = PTR_TO_MEM | type_flag; + + if (meta.func_id == special_kfunc_list[KF_bpf_dynptr_slice]) { + regs[BPF_REG_0].type |= MEM_RDONLY; + } else { + /* this will set env->seen_direct_write to true */ + if (!may_access_direct_pkt_data(env, NULL, BPF_WRITE)) { + verbose(env, "the prog does not allow writes to packet data\n"); + return -EINVAL; + } + } + + if (!meta.initialized_dynptr.id) { + verbose(env, "verifier internal error: no dynptr id\n"); + return -EFAULT; + } + regs[BPF_REG_0].dynptr_id = meta.initialized_dynptr.id; + + /* we don't need to set BPF_REG_0's ref obj id + * because packet slices are not refcounted (see + * dynptr_type_refcounted) + */ + } else { + verbose(env, "kernel function %s unhandled dynamic return type\n", + meta.func_name); + return -EFAULT; + } + } else if (!__btf_type_is_struct(ptr_type)) { + if (!meta.r0_size) { + __u32 sz; + + if (!IS_ERR(btf_resolve_size(desc_btf, ptr_type, &sz))) { + meta.r0_size = sz; + meta.r0_rdonly = true; + } + } + if (!meta.r0_size) { + ptr_type_name = btf_name_by_offset(desc_btf, + ptr_type->name_off); + verbose(env, + "kernel function %s returns pointer type %s %s is not supported\n", + func_name, + btf_type_str(ptr_type), + ptr_type_name); + return -EINVAL; + } + + mark_reg_known_zero(env, regs, BPF_REG_0); + regs[BPF_REG_0].type = PTR_TO_MEM; + regs[BPF_REG_0].mem_size = meta.r0_size; + + if (meta.r0_rdonly) + regs[BPF_REG_0].type |= MEM_RDONLY; + + /* Ensures we don't access the memory after a release_reference() */ + if (meta.ref_obj_id) + regs[BPF_REG_0].ref_obj_id = meta.ref_obj_id; + } else { + mark_reg_known_zero(env, regs, BPF_REG_0); + regs[BPF_REG_0].btf = desc_btf; + regs[BPF_REG_0].type = PTR_TO_BTF_ID; + regs[BPF_REG_0].btf_id = ptr_type_id; + } + + if (is_kfunc_ret_null(&meta)) { + regs[BPF_REG_0].type |= PTR_MAYBE_NULL; + /* For mark_ptr_or_null_reg, see 93c230e3f5bd6 */ + regs[BPF_REG_0].id = ++env->id_gen; + } + mark_btf_func_reg_size(env, BPF_REG_0, sizeof(void *)); + if (is_kfunc_acquire(&meta)) { + int id = acquire_reference_state(env, insn_idx); + + if (id < 0) + return id; + if (is_kfunc_ret_null(&meta)) + regs[BPF_REG_0].id = id; + regs[BPF_REG_0].ref_obj_id = id; + } else if (meta.func_id == special_kfunc_list[KF_bpf_rbtree_first]) { + ref_set_non_owning(env, ®s[BPF_REG_0]); + } + + if (reg_may_point_to_spin_lock(®s[BPF_REG_0]) && !regs[BPF_REG_0].id) + regs[BPF_REG_0].id = ++env->id_gen; + } else if (btf_type_is_void(t)) { + if (meta.btf == btf_vmlinux && btf_id_set_contains(&special_kfunc_set, meta.func_id)) { + if (meta.func_id == special_kfunc_list[KF_bpf_obj_drop_impl]) { + insn_aux->kptr_struct_meta = + btf_find_struct_meta(meta.arg_btf, + meta.arg_btf_id); + } + } + } + + nargs = btf_type_vlen(meta.func_proto); + args = (const struct btf_param *)(meta.func_proto + 1); + for (i = 0; i < nargs; i++) { + u32 regno = i + 1; + + t = btf_type_skip_modifiers(desc_btf, args[i].type, NULL); + if (btf_type_is_ptr(t)) + mark_btf_func_reg_size(env, regno, sizeof(void *)); + else + /* scalar. ensured by btf_check_kfunc_arg_match() */ + mark_btf_func_reg_size(env, regno, t->size); + } + + if (is_iter_next_kfunc(&meta)) { + err = process_iter_next_call(env, insn_idx, &meta); + if (err) + return err; + } + + return 0; +} + +static bool signed_add_overflows(s64 a, s64 b) +{ + /* Do the add in u64, where overflow is well-defined */ + s64 res = (s64)((u64)a + (u64)b); + + if (b < 0) + return res > a; + return res < a; +} + +static bool signed_add32_overflows(s32 a, s32 b) +{ + /* Do the add in u32, where overflow is well-defined */ + s32 res = (s32)((u32)a + (u32)b); + + if (b < 0) + return res > a; + return res < a; +} + +static bool signed_sub_overflows(s64 a, s64 b) +{ + /* Do the sub in u64, where overflow is well-defined */ + s64 res = (s64)((u64)a - (u64)b); + + if (b < 0) + return res < a; + return res > a; +} + +static bool signed_sub32_overflows(s32 a, s32 b) +{ + /* Do the sub in u32, where overflow is well-defined */ + s32 res = (s32)((u32)a - (u32)b); + + if (b < 0) + return res < a; + return res > a; +} + +static bool check_reg_sane_offset(struct bpf_verifier_env *env, + const struct bpf_reg_state *reg, + enum bpf_reg_type type) +{ + bool known = tnum_is_const(reg->var_off); + s64 val = reg->var_off.value; + s64 smin = reg->smin_value; + + if (known && (val >= BPF_MAX_VAR_OFF || val <= -BPF_MAX_VAR_OFF)) { + verbose(env, "math between %s pointer and %lld is not allowed\n", + reg_type_str(env, type), val); + return false; + } + + if (reg->off >= BPF_MAX_VAR_OFF || reg->off <= -BPF_MAX_VAR_OFF) { + verbose(env, "%s pointer offset %d is not allowed\n", + reg_type_str(env, type), reg->off); + return false; + } + + if (smin == S64_MIN) { + verbose(env, "math between %s pointer and register with unbounded min value is not allowed\n", + reg_type_str(env, type)); + return false; + } + + if (smin >= BPF_MAX_VAR_OFF || smin <= -BPF_MAX_VAR_OFF) { + verbose(env, "value %lld makes %s pointer be out of bounds\n", + smin, reg_type_str(env, type)); + return false; + } + + return true; +} + +enum { + REASON_BOUNDS = -1, + REASON_TYPE = -2, + REASON_PATHS = -3, + REASON_LIMIT = -4, + REASON_STACK = -5, +}; + +static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg, + u32 *alu_limit, bool mask_to_left) +{ + u32 max = 0, ptr_limit = 0; + + switch (ptr_reg->type) { + case PTR_TO_STACK: + /* Offset 0 is out-of-bounds, but acceptable start for the + * left direction, see BPF_REG_FP. Also, unknown scalar + * offset where we would need to deal with min/max bounds is + * currently prohibited for unprivileged. + */ + max = MAX_BPF_STACK + mask_to_left; + ptr_limit = -(ptr_reg->var_off.value + ptr_reg->off); + break; + case PTR_TO_MAP_VALUE: + max = ptr_reg->map_ptr->value_size; + ptr_limit = (mask_to_left ? + ptr_reg->smin_value : + ptr_reg->umax_value) + ptr_reg->off; + break; + default: + return REASON_TYPE; + } + + if (ptr_limit >= max) + return REASON_LIMIT; + *alu_limit = ptr_limit; + return 0; +} + +static bool can_skip_alu_sanitation(const struct bpf_verifier_env *env, + const struct bpf_insn *insn) +{ + return env->bypass_spec_v1 || BPF_SRC(insn->code) == BPF_K; +} + +static int update_alu_sanitation_state(struct bpf_insn_aux_data *aux, + u32 alu_state, u32 alu_limit) +{ + /* If we arrived here from different branches with different + * state or limits to sanitize, then this won't work. + */ + if (aux->alu_state && + (aux->alu_state != alu_state || + aux->alu_limit != alu_limit)) + return REASON_PATHS; + + /* Corresponding fixup done in do_misc_fixups(). */ + aux->alu_state = alu_state; + aux->alu_limit = alu_limit; + return 0; +} + +static int sanitize_val_alu(struct bpf_verifier_env *env, + struct bpf_insn *insn) +{ + struct bpf_insn_aux_data *aux = cur_aux(env); + + if (can_skip_alu_sanitation(env, insn)) + return 0; + + return update_alu_sanitation_state(aux, BPF_ALU_NON_POINTER, 0); +} + +static bool sanitize_needed(u8 opcode) +{ + return opcode == BPF_ADD || opcode == BPF_SUB; +} + +struct bpf_sanitize_info { + struct bpf_insn_aux_data aux; + bool mask_to_left; +}; + +static struct bpf_verifier_state * +sanitize_speculative_path(struct bpf_verifier_env *env, + const struct bpf_insn *insn, + u32 next_idx, u32 curr_idx) +{ + struct bpf_verifier_state *branch; + struct bpf_reg_state *regs; + + branch = push_stack(env, next_idx, curr_idx, true); + if (branch && insn) { + regs = branch->frame[branch->curframe]->regs; + if (BPF_SRC(insn->code) == BPF_K) { + mark_reg_unknown(env, regs, insn->dst_reg); + } else if (BPF_SRC(insn->code) == BPF_X) { + mark_reg_unknown(env, regs, insn->dst_reg); + mark_reg_unknown(env, regs, insn->src_reg); + } + } + return branch; +} + +static int sanitize_ptr_alu(struct bpf_verifier_env *env, + struct bpf_insn *insn, + const struct bpf_reg_state *ptr_reg, + const struct bpf_reg_state *off_reg, + struct bpf_reg_state *dst_reg, + struct bpf_sanitize_info *info, + const bool commit_window) +{ + struct bpf_insn_aux_data *aux = commit_window ? cur_aux(env) : &info->aux; + struct bpf_verifier_state *vstate = env->cur_state; + bool off_is_imm = tnum_is_const(off_reg->var_off); + bool off_is_neg = off_reg->smin_value < 0; + bool ptr_is_dst_reg = ptr_reg == dst_reg; + u8 opcode = BPF_OP(insn->code); + u32 alu_state, alu_limit; + struct bpf_reg_state tmp; + bool ret; + int err; + + if (can_skip_alu_sanitation(env, insn)) + return 0; + + /* We already marked aux for masking from non-speculative + * paths, thus we got here in the first place. We only care + * to explore bad access from here. + */ + if (vstate->speculative) + goto do_sim; + + if (!commit_window) { + if (!tnum_is_const(off_reg->var_off) && + (off_reg->smin_value < 0) != (off_reg->smax_value < 0)) + return REASON_BOUNDS; + + info->mask_to_left = (opcode == BPF_ADD && off_is_neg) || + (opcode == BPF_SUB && !off_is_neg); + } + + err = retrieve_ptr_limit(ptr_reg, &alu_limit, info->mask_to_left); + if (err < 0) + return err; + + if (commit_window) { + /* In commit phase we narrow the masking window based on + * the observed pointer move after the simulated operation. + */ + alu_state = info->aux.alu_state; + alu_limit = abs(info->aux.alu_limit - alu_limit); + } else { + alu_state = off_is_neg ? BPF_ALU_NEG_VALUE : 0; + alu_state |= off_is_imm ? BPF_ALU_IMMEDIATE : 0; + alu_state |= ptr_is_dst_reg ? + BPF_ALU_SANITIZE_SRC : BPF_ALU_SANITIZE_DST; + + /* Limit pruning on unknown scalars to enable deep search for + * potential masking differences from other program paths. + */ + if (!off_is_imm) + env->explore_alu_limits = true; + } + + err = update_alu_sanitation_state(aux, alu_state, alu_limit); + if (err < 0) + return err; +do_sim: + /* If we're in commit phase, we're done here given we already + * pushed the truncated dst_reg into the speculative verification + * stack. + * + * Also, when register is a known constant, we rewrite register-based + * operation to immediate-based, and thus do not need masking (and as + * a consequence, do not need to simulate the zero-truncation either). + */ + if (commit_window || off_is_imm) + return 0; + + /* Simulate and find potential out-of-bounds access under + * speculative execution from truncation as a result of + * masking when off was not within expected range. If off + * sits in dst, then we temporarily need to move ptr there + * to simulate dst (== 0) +/-= ptr. Needed, for example, + * for cases where we use K-based arithmetic in one direction + * and truncated reg-based in the other in order to explore + * bad access. + */ + if (!ptr_is_dst_reg) { + tmp = *dst_reg; + copy_register_state(dst_reg, ptr_reg); + } + ret = sanitize_speculative_path(env, NULL, env->insn_idx + 1, + env->insn_idx); + if (!ptr_is_dst_reg && ret) + *dst_reg = tmp; + return !ret ? REASON_STACK : 0; +} + +static void sanitize_mark_insn_seen(struct bpf_verifier_env *env) +{ + struct bpf_verifier_state *vstate = env->cur_state; + + /* If we simulate paths under speculation, we don't update the + * insn as 'seen' such that when we verify unreachable paths in + * the non-speculative domain, sanitize_dead_code() can still + * rewrite/sanitize them. + */ + if (!vstate->speculative) + env->insn_aux_data[env->insn_idx].seen = env->pass_cnt; +} + +static int sanitize_err(struct bpf_verifier_env *env, + const struct bpf_insn *insn, int reason, + const struct bpf_reg_state *off_reg, + const struct bpf_reg_state *dst_reg) +{ + static const char *err = "pointer arithmetic with it prohibited for !root"; + const char *op = BPF_OP(insn->code) == BPF_ADD ? "add" : "sub"; + u32 dst = insn->dst_reg, src = insn->src_reg; + + switch (reason) { + case REASON_BOUNDS: + verbose(env, "R%d has unknown scalar with mixed signed bounds, %s\n", + off_reg == dst_reg ? dst : src, err); + break; + case REASON_TYPE: + verbose(env, "R%d has pointer with unsupported alu operation, %s\n", + off_reg == dst_reg ? src : dst, err); + break; + case REASON_PATHS: + verbose(env, "R%d tried to %s from different maps, paths or scalars, %s\n", + dst, op, err); + break; + case REASON_LIMIT: + verbose(env, "R%d tried to %s beyond pointer bounds, %s\n", + dst, op, err); + break; + case REASON_STACK: + verbose(env, "R%d could not be pushed for speculative verification, %s\n", + dst, err); + break; + default: + verbose(env, "verifier internal error: unknown reason (%d)\n", + reason); + break; + } + + return -EACCES; +} + +/* check that stack access falls within stack limits and that 'reg' doesn't + * have a variable offset. + * + * Variable offset is prohibited for unprivileged mode for simplicity since it + * requires corresponding support in Spectre masking for stack ALU. See also + * retrieve_ptr_limit(). + * + * + * 'off' includes 'reg->off'. + */ +static int check_stack_access_for_ptr_arithmetic( + struct bpf_verifier_env *env, + int regno, + const struct bpf_reg_state *reg, + int off) +{ + if (!tnum_is_const(reg->var_off)) { + char tn_buf[48]; + + tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); + verbose(env, "R%d variable stack access prohibited for !root, var_off=%s off=%d\n", + regno, tn_buf, off); + return -EACCES; + } + + if (off >= 0 || off < -MAX_BPF_STACK) { + verbose(env, "R%d stack pointer arithmetic goes out of range, " + "prohibited for !root; off=%d\n", regno, off); + return -EACCES; + } + + return 0; +} + +static int sanitize_check_bounds(struct bpf_verifier_env *env, + const struct bpf_insn *insn, + const struct bpf_reg_state *dst_reg) +{ + u32 dst = insn->dst_reg; + + /* For unprivileged we require that resulting offset must be in bounds + * in order to be able to sanitize access later on. + */ + if (env->bypass_spec_v1) + return 0; + + switch (dst_reg->type) { + case PTR_TO_STACK: + if (check_stack_access_for_ptr_arithmetic(env, dst, dst_reg, + dst_reg->off + dst_reg->var_off.value)) + return -EACCES; + break; + case PTR_TO_MAP_VALUE: + if (check_map_access(env, dst, dst_reg->off, 1, false, ACCESS_HELPER)) { + verbose(env, "R%d pointer arithmetic of map value goes out of range, " + "prohibited for !root\n", dst); + return -EACCES; + } + break; + default: + break; + } + + return 0; +} + +/* Handles arithmetic on a pointer and a scalar: computes new min/max and var_off. + * Caller should also handle BPF_MOV case separately. + * If we return -EACCES, caller may want to try again treating pointer as a + * scalar. So we only emit a diagnostic if !env->allow_ptr_leaks. + */ +static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, + struct bpf_insn *insn, + const struct bpf_reg_state *ptr_reg, + const struct bpf_reg_state *off_reg) +{ + struct bpf_verifier_state *vstate = env->cur_state; + struct bpf_func_state *state = vstate->frame[vstate->curframe]; + struct bpf_reg_state *regs = state->regs, *dst_reg; + bool known = tnum_is_const(off_reg->var_off); + s64 smin_val = off_reg->smin_value, smax_val = off_reg->smax_value, + smin_ptr = ptr_reg->smin_value, smax_ptr = ptr_reg->smax_value; + u64 umin_val = off_reg->umin_value, umax_val = off_reg->umax_value, + umin_ptr = ptr_reg->umin_value, umax_ptr = ptr_reg->umax_value; + struct bpf_sanitize_info info = {}; + u8 opcode = BPF_OP(insn->code); + u32 dst = insn->dst_reg; + int ret; + + dst_reg = ®s[dst]; + + if ((known && (smin_val != smax_val || umin_val != umax_val)) || + smin_val > smax_val || umin_val > umax_val) { + /* Taint dst register if offset had invalid bounds derived from + * e.g. dead branches. + */ + __mark_reg_unknown(env, dst_reg); + return 0; + } + + if (BPF_CLASS(insn->code) != BPF_ALU64) { + /* 32-bit ALU ops on pointers produce (meaningless) scalars */ + if (opcode == BPF_SUB && env->allow_ptr_leaks) { + __mark_reg_unknown(env, dst_reg); + return 0; + } + + verbose(env, + "R%d 32-bit pointer arithmetic prohibited\n", + dst); + return -EACCES; + } + + if (ptr_reg->type & PTR_MAYBE_NULL) { + verbose(env, "R%d pointer arithmetic on %s prohibited, null-check it first\n", + dst, reg_type_str(env, ptr_reg->type)); + return -EACCES; + } + + switch (base_type(ptr_reg->type)) { + case PTR_TO_FLOW_KEYS: + if (known) + break; + fallthrough; + case CONST_PTR_TO_MAP: + /* smin_val represents the known value */ + if (known && smin_val == 0 && opcode == BPF_ADD) + break; + fallthrough; + case PTR_TO_PACKET_END: + case PTR_TO_SOCKET: + case PTR_TO_SOCK_COMMON: + case PTR_TO_TCP_SOCK: + case PTR_TO_XDP_SOCK: + verbose(env, "R%d pointer arithmetic on %s prohibited\n", + dst, reg_type_str(env, ptr_reg->type)); + return -EACCES; + default: + break; + } + + /* In case of 'scalar += pointer', dst_reg inherits pointer type and id. + * The id may be overwritten later if we create a new variable offset. + */ + dst_reg->type = ptr_reg->type; + dst_reg->id = ptr_reg->id; + + if (!check_reg_sane_offset(env, off_reg, ptr_reg->type) || + !check_reg_sane_offset(env, ptr_reg, ptr_reg->type)) + return -EINVAL; + + /* pointer types do not carry 32-bit bounds at the moment. */ + __mark_reg32_unbounded(dst_reg); + + if (sanitize_needed(opcode)) { + ret = sanitize_ptr_alu(env, insn, ptr_reg, off_reg, dst_reg, + &info, false); + if (ret < 0) + return sanitize_err(env, insn, ret, off_reg, dst_reg); + } + + switch (opcode) { + case BPF_ADD: + /* We can take a fixed offset as long as it doesn't overflow + * the s32 'off' field + */ + if (known && (ptr_reg->off + smin_val == + (s64)(s32)(ptr_reg->off + smin_val))) { + /* pointer += K. Accumulate it into fixed offset */ + dst_reg->smin_value = smin_ptr; + dst_reg->smax_value = smax_ptr; + dst_reg->umin_value = umin_ptr; + dst_reg->umax_value = umax_ptr; + dst_reg->var_off = ptr_reg->var_off; + dst_reg->off = ptr_reg->off + smin_val; + dst_reg->raw = ptr_reg->raw; + break; + } + /* A new variable offset is created. Note that off_reg->off + * == 0, since it's a scalar. + * dst_reg gets the pointer type and since some positive + * integer value was added to the pointer, give it a new 'id' + * if it's a PTR_TO_PACKET. + * this creates a new 'base' pointer, off_reg (variable) gets + * added into the variable offset, and we copy the fixed offset + * from ptr_reg. + */ + if (signed_add_overflows(smin_ptr, smin_val) || + signed_add_overflows(smax_ptr, smax_val)) { + dst_reg->smin_value = S64_MIN; + dst_reg->smax_value = S64_MAX; + } else { + dst_reg->smin_value = smin_ptr + smin_val; + dst_reg->smax_value = smax_ptr + smax_val; + } + if (umin_ptr + umin_val < umin_ptr || + umax_ptr + umax_val < umax_ptr) { + dst_reg->umin_value = 0; + dst_reg->umax_value = U64_MAX; + } else { + dst_reg->umin_value = umin_ptr + umin_val; + dst_reg->umax_value = umax_ptr + umax_val; + } + dst_reg->var_off = tnum_add(ptr_reg->var_off, off_reg->var_off); + dst_reg->off = ptr_reg->off; + dst_reg->raw = ptr_reg->raw; + if (reg_is_pkt_pointer(ptr_reg)) { + dst_reg->id = ++env->id_gen; + /* something was added to pkt_ptr, set range to zero */ + memset(&dst_reg->raw, 0, sizeof(dst_reg->raw)); + } + break; + case BPF_SUB: + if (dst_reg == off_reg) { + /* scalar -= pointer. Creates an unknown scalar */ + verbose(env, "R%d tried to subtract pointer from scalar\n", + dst); + return -EACCES; + } + /* We don't allow subtraction from FP, because (according to + * test_verifier.c test "invalid fp arithmetic", JITs might not + * be able to deal with it. + */ + if (ptr_reg->type == PTR_TO_STACK) { + verbose(env, "R%d subtraction from stack pointer prohibited\n", + dst); + return -EACCES; + } + if (known && (ptr_reg->off - smin_val == + (s64)(s32)(ptr_reg->off - smin_val))) { + /* pointer -= K. Subtract it from fixed offset */ + dst_reg->smin_value = smin_ptr; + dst_reg->smax_value = smax_ptr; + dst_reg->umin_value = umin_ptr; + dst_reg->umax_value = umax_ptr; + dst_reg->var_off = ptr_reg->var_off; + dst_reg->id = ptr_reg->id; + dst_reg->off = ptr_reg->off - smin_val; + dst_reg->raw = ptr_reg->raw; + break; + } + /* A new variable offset is created. If the subtrahend is known + * nonnegative, then any reg->range we had before is still good. + */ + if (signed_sub_overflows(smin_ptr, smax_val) || + signed_sub_overflows(smax_ptr, smin_val)) { + /* Overflow possible, we know nothing */ + dst_reg->smin_value = S64_MIN; + dst_reg->smax_value = S64_MAX; + } else { + dst_reg->smin_value = smin_ptr - smax_val; + dst_reg->smax_value = smax_ptr - smin_val; + } + if (umin_ptr < umax_val) { + /* Overflow possible, we know nothing */ + dst_reg->umin_value = 0; + dst_reg->umax_value = U64_MAX; + } else { + /* Cannot overflow (as long as bounds are consistent) */ + dst_reg->umin_value = umin_ptr - umax_val; + dst_reg->umax_value = umax_ptr - umin_val; + } + dst_reg->var_off = tnum_sub(ptr_reg->var_off, off_reg->var_off); + dst_reg->off = ptr_reg->off; + dst_reg->raw = ptr_reg->raw; + if (reg_is_pkt_pointer(ptr_reg)) { + dst_reg->id = ++env->id_gen; + /* something was added to pkt_ptr, set range to zero */ + if (smin_val < 0) + memset(&dst_reg->raw, 0, sizeof(dst_reg->raw)); + } + break; + case BPF_AND: + case BPF_OR: + case BPF_XOR: + /* bitwise ops on pointers are troublesome, prohibit. */ + verbose(env, "R%d bitwise operator %s on pointer prohibited\n", + dst, bpf_alu_string[opcode >> 4]); + return -EACCES; + default: + /* other operators (e.g. MUL,LSH) produce non-pointer results */ + verbose(env, "R%d pointer arithmetic with %s operator prohibited\n", + dst, bpf_alu_string[opcode >> 4]); + return -EACCES; + } + + if (!check_reg_sane_offset(env, dst_reg, ptr_reg->type)) + return -EINVAL; + reg_bounds_sync(dst_reg); + if (sanitize_check_bounds(env, insn, dst_reg) < 0) + return -EACCES; + if (sanitize_needed(opcode)) { + ret = sanitize_ptr_alu(env, insn, dst_reg, off_reg, dst_reg, + &info, true); + if (ret < 0) + return sanitize_err(env, insn, ret, off_reg, dst_reg); + } + + return 0; +} + +static void scalar32_min_max_add(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + s32 smin_val = src_reg->s32_min_value; + s32 smax_val = src_reg->s32_max_value; + u32 umin_val = src_reg->u32_min_value; + u32 umax_val = src_reg->u32_max_value; + + if (signed_add32_overflows(dst_reg->s32_min_value, smin_val) || + signed_add32_overflows(dst_reg->s32_max_value, smax_val)) { + dst_reg->s32_min_value = S32_MIN; + dst_reg->s32_max_value = S32_MAX; + } else { + dst_reg->s32_min_value += smin_val; + dst_reg->s32_max_value += smax_val; + } + if (dst_reg->u32_min_value + umin_val < umin_val || + dst_reg->u32_max_value + umax_val < umax_val) { + dst_reg->u32_min_value = 0; + dst_reg->u32_max_value = U32_MAX; + } else { + dst_reg->u32_min_value += umin_val; + dst_reg->u32_max_value += umax_val; + } +} + +static void scalar_min_max_add(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + s64 smin_val = src_reg->smin_value; + s64 smax_val = src_reg->smax_value; + u64 umin_val = src_reg->umin_value; + u64 umax_val = src_reg->umax_value; + + if (signed_add_overflows(dst_reg->smin_value, smin_val) || + signed_add_overflows(dst_reg->smax_value, smax_val)) { + dst_reg->smin_value = S64_MIN; + dst_reg->smax_value = S64_MAX; + } else { + dst_reg->smin_value += smin_val; + dst_reg->smax_value += smax_val; + } + if (dst_reg->umin_value + umin_val < umin_val || + dst_reg->umax_value + umax_val < umax_val) { + dst_reg->umin_value = 0; + dst_reg->umax_value = U64_MAX; + } else { + dst_reg->umin_value += umin_val; + dst_reg->umax_value += umax_val; + } +} + +static void scalar32_min_max_sub(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + s32 smin_val = src_reg->s32_min_value; + s32 smax_val = src_reg->s32_max_value; + u32 umin_val = src_reg->u32_min_value; + u32 umax_val = src_reg->u32_max_value; + + if (signed_sub32_overflows(dst_reg->s32_min_value, smax_val) || + signed_sub32_overflows(dst_reg->s32_max_value, smin_val)) { + /* Overflow possible, we know nothing */ + dst_reg->s32_min_value = S32_MIN; + dst_reg->s32_max_value = S32_MAX; + } else { + dst_reg->s32_min_value -= smax_val; + dst_reg->s32_max_value -= smin_val; + } + if (dst_reg->u32_min_value < umax_val) { + /* Overflow possible, we know nothing */ + dst_reg->u32_min_value = 0; + dst_reg->u32_max_value = U32_MAX; + } else { + /* Cannot overflow (as long as bounds are consistent) */ + dst_reg->u32_min_value -= umax_val; + dst_reg->u32_max_value -= umin_val; + } +} + +static void scalar_min_max_sub(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + s64 smin_val = src_reg->smin_value; + s64 smax_val = src_reg->smax_value; + u64 umin_val = src_reg->umin_value; + u64 umax_val = src_reg->umax_value; + + if (signed_sub_overflows(dst_reg->smin_value, smax_val) || + signed_sub_overflows(dst_reg->smax_value, smin_val)) { + /* Overflow possible, we know nothing */ + dst_reg->smin_value = S64_MIN; + dst_reg->smax_value = S64_MAX; + } else { + dst_reg->smin_value -= smax_val; + dst_reg->smax_value -= smin_val; + } + if (dst_reg->umin_value < umax_val) { + /* Overflow possible, we know nothing */ + dst_reg->umin_value = 0; + dst_reg->umax_value = U64_MAX; + } else { + /* Cannot overflow (as long as bounds are consistent) */ + dst_reg->umin_value -= umax_val; + dst_reg->umax_value -= umin_val; + } +} + +static void scalar32_min_max_mul(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + s32 smin_val = src_reg->s32_min_value; + u32 umin_val = src_reg->u32_min_value; + u32 umax_val = src_reg->u32_max_value; + + if (smin_val < 0 || dst_reg->s32_min_value < 0) { + /* Ain't nobody got time to multiply that sign */ + __mark_reg32_unbounded(dst_reg); + return; + } + /* Both values are positive, so we can work with unsigned and + * copy the result to signed (unless it exceeds S32_MAX). + */ + if (umax_val > U16_MAX || dst_reg->u32_max_value > U16_MAX) { + /* Potential overflow, we know nothing */ + __mark_reg32_unbounded(dst_reg); + return; + } + dst_reg->u32_min_value *= umin_val; + dst_reg->u32_max_value *= umax_val; + if (dst_reg->u32_max_value > S32_MAX) { + /* Overflow possible, we know nothing */ + dst_reg->s32_min_value = S32_MIN; + dst_reg->s32_max_value = S32_MAX; + } else { + dst_reg->s32_min_value = dst_reg->u32_min_value; + dst_reg->s32_max_value = dst_reg->u32_max_value; + } +} + +static void scalar_min_max_mul(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + s64 smin_val = src_reg->smin_value; + u64 umin_val = src_reg->umin_value; + u64 umax_val = src_reg->umax_value; + + if (smin_val < 0 || dst_reg->smin_value < 0) { + /* Ain't nobody got time to multiply that sign */ + __mark_reg64_unbounded(dst_reg); + return; + } + /* Both values are positive, so we can work with unsigned and + * copy the result to signed (unless it exceeds S64_MAX). + */ + if (umax_val > U32_MAX || dst_reg->umax_value > U32_MAX) { + /* Potential overflow, we know nothing */ + __mark_reg64_unbounded(dst_reg); + return; + } + dst_reg->umin_value *= umin_val; + dst_reg->umax_value *= umax_val; + if (dst_reg->umax_value > S64_MAX) { + /* Overflow possible, we know nothing */ + dst_reg->smin_value = S64_MIN; + dst_reg->smax_value = S64_MAX; + } else { + dst_reg->smin_value = dst_reg->umin_value; + dst_reg->smax_value = dst_reg->umax_value; + } +} + +static void scalar32_min_max_and(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + bool src_known = tnum_subreg_is_const(src_reg->var_off); + bool dst_known = tnum_subreg_is_const(dst_reg->var_off); + struct tnum var32_off = tnum_subreg(dst_reg->var_off); + s32 smin_val = src_reg->s32_min_value; + u32 umax_val = src_reg->u32_max_value; + + if (src_known && dst_known) { + __mark_reg32_known(dst_reg, var32_off.value); + return; + } + + /* We get our minimum from the var_off, since that's inherently + * bitwise. Our maximum is the minimum of the operands' maxima. + */ + dst_reg->u32_min_value = var32_off.value; + dst_reg->u32_max_value = min(dst_reg->u32_max_value, umax_val); + if (dst_reg->s32_min_value < 0 || smin_val < 0) { + /* Lose signed bounds when ANDing negative numbers, + * ain't nobody got time for that. + */ + dst_reg->s32_min_value = S32_MIN; + dst_reg->s32_max_value = S32_MAX; + } else { + /* ANDing two positives gives a positive, so safe to + * cast result into s64. + */ + dst_reg->s32_min_value = dst_reg->u32_min_value; + dst_reg->s32_max_value = dst_reg->u32_max_value; + } +} + +static void scalar_min_max_and(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + bool src_known = tnum_is_const(src_reg->var_off); + bool dst_known = tnum_is_const(dst_reg->var_off); + s64 smin_val = src_reg->smin_value; + u64 umax_val = src_reg->umax_value; + + if (src_known && dst_known) { + __mark_reg_known(dst_reg, dst_reg->var_off.value); + return; + } + + /* We get our minimum from the var_off, since that's inherently + * bitwise. Our maximum is the minimum of the operands' maxima. + */ + dst_reg->umin_value = dst_reg->var_off.value; + dst_reg->umax_value = min(dst_reg->umax_value, umax_val); + if (dst_reg->smin_value < 0 || smin_val < 0) { + /* Lose signed bounds when ANDing negative numbers, + * ain't nobody got time for that. + */ + dst_reg->smin_value = S64_MIN; + dst_reg->smax_value = S64_MAX; + } else { + /* ANDing two positives gives a positive, so safe to + * cast result into s64. + */ + dst_reg->smin_value = dst_reg->umin_value; + dst_reg->smax_value = dst_reg->umax_value; + } + /* We may learn something more from the var_off */ + __update_reg_bounds(dst_reg); +} + +static void scalar32_min_max_or(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + bool src_known = tnum_subreg_is_const(src_reg->var_off); + bool dst_known = tnum_subreg_is_const(dst_reg->var_off); + struct tnum var32_off = tnum_subreg(dst_reg->var_off); + s32 smin_val = src_reg->s32_min_value; + u32 umin_val = src_reg->u32_min_value; + + if (src_known && dst_known) { + __mark_reg32_known(dst_reg, var32_off.value); + return; + } + + /* We get our maximum from the var_off, and our minimum is the + * maximum of the operands' minima + */ + dst_reg->u32_min_value = max(dst_reg->u32_min_value, umin_val); + dst_reg->u32_max_value = var32_off.value | var32_off.mask; + if (dst_reg->s32_min_value < 0 || smin_val < 0) { + /* Lose signed bounds when ORing negative numbers, + * ain't nobody got time for that. + */ + dst_reg->s32_min_value = S32_MIN; + dst_reg->s32_max_value = S32_MAX; + } else { + /* ORing two positives gives a positive, so safe to + * cast result into s64. + */ + dst_reg->s32_min_value = dst_reg->u32_min_value; + dst_reg->s32_max_value = dst_reg->u32_max_value; + } +} + +static void scalar_min_max_or(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + bool src_known = tnum_is_const(src_reg->var_off); + bool dst_known = tnum_is_const(dst_reg->var_off); + s64 smin_val = src_reg->smin_value; + u64 umin_val = src_reg->umin_value; + + if (src_known && dst_known) { + __mark_reg_known(dst_reg, dst_reg->var_off.value); + return; + } + + /* We get our maximum from the var_off, and our minimum is the + * maximum of the operands' minima + */ + dst_reg->umin_value = max(dst_reg->umin_value, umin_val); + dst_reg->umax_value = dst_reg->var_off.value | dst_reg->var_off.mask; + if (dst_reg->smin_value < 0 || smin_val < 0) { + /* Lose signed bounds when ORing negative numbers, + * ain't nobody got time for that. + */ + dst_reg->smin_value = S64_MIN; + dst_reg->smax_value = S64_MAX; + } else { + /* ORing two positives gives a positive, so safe to + * cast result into s64. + */ + dst_reg->smin_value = dst_reg->umin_value; + dst_reg->smax_value = dst_reg->umax_value; + } + /* We may learn something more from the var_off */ + __update_reg_bounds(dst_reg); +} + +static void scalar32_min_max_xor(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + bool src_known = tnum_subreg_is_const(src_reg->var_off); + bool dst_known = tnum_subreg_is_const(dst_reg->var_off); + struct tnum var32_off = tnum_subreg(dst_reg->var_off); + s32 smin_val = src_reg->s32_min_value; + + if (src_known && dst_known) { + __mark_reg32_known(dst_reg, var32_off.value); + return; + } + + /* We get both minimum and maximum from the var32_off. */ + dst_reg->u32_min_value = var32_off.value; + dst_reg->u32_max_value = var32_off.value | var32_off.mask; + + if (dst_reg->s32_min_value >= 0 && smin_val >= 0) { + /* XORing two positive sign numbers gives a positive, + * so safe to cast u32 result into s32. + */ + dst_reg->s32_min_value = dst_reg->u32_min_value; + dst_reg->s32_max_value = dst_reg->u32_max_value; + } else { + dst_reg->s32_min_value = S32_MIN; + dst_reg->s32_max_value = S32_MAX; + } +} + +static void scalar_min_max_xor(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + bool src_known = tnum_is_const(src_reg->var_off); + bool dst_known = tnum_is_const(dst_reg->var_off); + s64 smin_val = src_reg->smin_value; + + if (src_known && dst_known) { + /* dst_reg->var_off.value has been updated earlier */ + __mark_reg_known(dst_reg, dst_reg->var_off.value); + return; + } + + /* We get both minimum and maximum from the var_off. */ + dst_reg->umin_value = dst_reg->var_off.value; + dst_reg->umax_value = dst_reg->var_off.value | dst_reg->var_off.mask; + + if (dst_reg->smin_value >= 0 && smin_val >= 0) { + /* XORing two positive sign numbers gives a positive, + * so safe to cast u64 result into s64. + */ + dst_reg->smin_value = dst_reg->umin_value; + dst_reg->smax_value = dst_reg->umax_value; + } else { + dst_reg->smin_value = S64_MIN; + dst_reg->smax_value = S64_MAX; + } + + __update_reg_bounds(dst_reg); +} + +static void __scalar32_min_max_lsh(struct bpf_reg_state *dst_reg, + u64 umin_val, u64 umax_val) +{ + /* We lose all sign bit information (except what we can pick + * up from var_off) + */ + dst_reg->s32_min_value = S32_MIN; + dst_reg->s32_max_value = S32_MAX; + /* If we might shift our top bit out, then we know nothing */ + if (umax_val > 31 || dst_reg->u32_max_value > 1ULL << (31 - umax_val)) { + dst_reg->u32_min_value = 0; + dst_reg->u32_max_value = U32_MAX; + } else { + dst_reg->u32_min_value <<= umin_val; + dst_reg->u32_max_value <<= umax_val; + } +} + +static void scalar32_min_max_lsh(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + u32 umax_val = src_reg->u32_max_value; + u32 umin_val = src_reg->u32_min_value; + /* u32 alu operation will zext upper bits */ + struct tnum subreg = tnum_subreg(dst_reg->var_off); + + __scalar32_min_max_lsh(dst_reg, umin_val, umax_val); + dst_reg->var_off = tnum_subreg(tnum_lshift(subreg, umin_val)); + /* Not required but being careful mark reg64 bounds as unknown so + * that we are forced to pick them up from tnum and zext later and + * if some path skips this step we are still safe. + */ + __mark_reg64_unbounded(dst_reg); + __update_reg32_bounds(dst_reg); +} + +static void __scalar64_min_max_lsh(struct bpf_reg_state *dst_reg, + u64 umin_val, u64 umax_val) +{ + /* Special case <<32 because it is a common compiler pattern to sign + * extend subreg by doing <<32 s>>32. In this case if 32bit bounds are + * positive we know this shift will also be positive so we can track + * bounds correctly. Otherwise we lose all sign bit information except + * what we can pick up from var_off. Perhaps we can generalize this + * later to shifts of any length. + */ + if (umin_val == 32 && umax_val == 32 && dst_reg->s32_max_value >= 0) + dst_reg->smax_value = (s64)dst_reg->s32_max_value << 32; + else + dst_reg->smax_value = S64_MAX; + + if (umin_val == 32 && umax_val == 32 && dst_reg->s32_min_value >= 0) + dst_reg->smin_value = (s64)dst_reg->s32_min_value << 32; + else + dst_reg->smin_value = S64_MIN; + + /* If we might shift our top bit out, then we know nothing */ + if (dst_reg->umax_value > 1ULL << (63 - umax_val)) { + dst_reg->umin_value = 0; + dst_reg->umax_value = U64_MAX; + } else { + dst_reg->umin_value <<= umin_val; + dst_reg->umax_value <<= umax_val; + } +} + +static void scalar_min_max_lsh(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + u64 umax_val = src_reg->umax_value; + u64 umin_val = src_reg->umin_value; + + /* scalar64 calc uses 32bit unshifted bounds so must be called first */ + __scalar64_min_max_lsh(dst_reg, umin_val, umax_val); + __scalar32_min_max_lsh(dst_reg, umin_val, umax_val); + + dst_reg->var_off = tnum_lshift(dst_reg->var_off, umin_val); + /* We may learn something more from the var_off */ + __update_reg_bounds(dst_reg); +} + +static void scalar32_min_max_rsh(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + struct tnum subreg = tnum_subreg(dst_reg->var_off); + u32 umax_val = src_reg->u32_max_value; + u32 umin_val = src_reg->u32_min_value; + + /* BPF_RSH is an unsigned shift. If the value in dst_reg might + * be negative, then either: + * 1) src_reg might be zero, so the sign bit of the result is + * unknown, so we lose our signed bounds + * 2) it's known negative, thus the unsigned bounds capture the + * signed bounds + * 3) the signed bounds cross zero, so they tell us nothing + * about the result + * If the value in dst_reg is known nonnegative, then again the + * unsigned bounds capture the signed bounds. + * Thus, in all cases it suffices to blow away our signed bounds + * and rely on inferring new ones from the unsigned bounds and + * var_off of the result. + */ + dst_reg->s32_min_value = S32_MIN; + dst_reg->s32_max_value = S32_MAX; + + dst_reg->var_off = tnum_rshift(subreg, umin_val); + dst_reg->u32_min_value >>= umax_val; + dst_reg->u32_max_value >>= umin_val; + + __mark_reg64_unbounded(dst_reg); + __update_reg32_bounds(dst_reg); +} + +static void scalar_min_max_rsh(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + u64 umax_val = src_reg->umax_value; + u64 umin_val = src_reg->umin_value; + + /* BPF_RSH is an unsigned shift. If the value in dst_reg might + * be negative, then either: + * 1) src_reg might be zero, so the sign bit of the result is + * unknown, so we lose our signed bounds + * 2) it's known negative, thus the unsigned bounds capture the + * signed bounds + * 3) the signed bounds cross zero, so they tell us nothing + * about the result + * If the value in dst_reg is known nonnegative, then again the + * unsigned bounds capture the signed bounds. + * Thus, in all cases it suffices to blow away our signed bounds + * and rely on inferring new ones from the unsigned bounds and + * var_off of the result. + */ + dst_reg->smin_value = S64_MIN; + dst_reg->smax_value = S64_MAX; + dst_reg->var_off = tnum_rshift(dst_reg->var_off, umin_val); + dst_reg->umin_value >>= umax_val; + dst_reg->umax_value >>= umin_val; + + /* Its not easy to operate on alu32 bounds here because it depends + * on bits being shifted in. Take easy way out and mark unbounded + * so we can recalculate later from tnum. + */ + __mark_reg32_unbounded(dst_reg); + __update_reg_bounds(dst_reg); +} + +static void scalar32_min_max_arsh(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + u64 umin_val = src_reg->u32_min_value; + + /* Upon reaching here, src_known is true and + * umax_val is equal to umin_val. + */ + dst_reg->s32_min_value = (u32)(((s32)dst_reg->s32_min_value) >> umin_val); + dst_reg->s32_max_value = (u32)(((s32)dst_reg->s32_max_value) >> umin_val); + + dst_reg->var_off = tnum_arshift(tnum_subreg(dst_reg->var_off), umin_val, 32); + + /* blow away the dst_reg umin_value/umax_value and rely on + * dst_reg var_off to refine the result. + */ + dst_reg->u32_min_value = 0; + dst_reg->u32_max_value = U32_MAX; + + __mark_reg64_unbounded(dst_reg); + __update_reg32_bounds(dst_reg); +} + +static void scalar_min_max_arsh(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg) +{ + u64 umin_val = src_reg->umin_value; + + /* Upon reaching here, src_known is true and umax_val is equal + * to umin_val. + */ + dst_reg->smin_value >>= umin_val; + dst_reg->smax_value >>= umin_val; + + dst_reg->var_off = tnum_arshift(dst_reg->var_off, umin_val, 64); + + /* blow away the dst_reg umin_value/umax_value and rely on + * dst_reg var_off to refine the result. + */ + dst_reg->umin_value = 0; + dst_reg->umax_value = U64_MAX; + + /* Its not easy to operate on alu32 bounds here because it depends + * on bits being shifted in from upper 32-bits. Take easy way out + * and mark unbounded so we can recalculate later from tnum. + */ + __mark_reg32_unbounded(dst_reg); + __update_reg_bounds(dst_reg); +} + +/* WARNING: This function does calculations on 64-bit values, but the actual + * execution may occur on 32-bit values. Therefore, things like bitshifts + * need extra checks in the 32-bit case. + */ +static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, + struct bpf_insn *insn, + struct bpf_reg_state *dst_reg, + struct bpf_reg_state src_reg) +{ + struct bpf_reg_state *regs = cur_regs(env); + u8 opcode = BPF_OP(insn->code); + bool src_known; + s64 smin_val, smax_val; + u64 umin_val, umax_val; + s32 s32_min_val, s32_max_val; + u32 u32_min_val, u32_max_val; + u64 insn_bitness = (BPF_CLASS(insn->code) == BPF_ALU64) ? 64 : 32; + bool alu32 = (BPF_CLASS(insn->code) != BPF_ALU64); + int ret; + + smin_val = src_reg.smin_value; + smax_val = src_reg.smax_value; + umin_val = src_reg.umin_value; + umax_val = src_reg.umax_value; + + s32_min_val = src_reg.s32_min_value; + s32_max_val = src_reg.s32_max_value; + u32_min_val = src_reg.u32_min_value; + u32_max_val = src_reg.u32_max_value; + + if (alu32) { + src_known = tnum_subreg_is_const(src_reg.var_off); + if ((src_known && + (s32_min_val != s32_max_val || u32_min_val != u32_max_val)) || + s32_min_val > s32_max_val || u32_min_val > u32_max_val) { + /* Taint dst register if offset had invalid bounds + * derived from e.g. dead branches. + */ + __mark_reg_unknown(env, dst_reg); + return 0; + } + } else { + src_known = tnum_is_const(src_reg.var_off); + if ((src_known && + (smin_val != smax_val || umin_val != umax_val)) || + smin_val > smax_val || umin_val > umax_val) { + /* Taint dst register if offset had invalid bounds + * derived from e.g. dead branches. + */ + __mark_reg_unknown(env, dst_reg); + return 0; + } + } + + if (!src_known && + opcode != BPF_ADD && opcode != BPF_SUB && opcode != BPF_AND) { + __mark_reg_unknown(env, dst_reg); + return 0; + } + + if (sanitize_needed(opcode)) { + ret = sanitize_val_alu(env, insn); + if (ret < 0) + return sanitize_err(env, insn, ret, NULL, NULL); + } + + /* Calculate sign/unsigned bounds and tnum for alu32 and alu64 bit ops. + * There are two classes of instructions: The first class we track both + * alu32 and alu64 sign/unsigned bounds independently this provides the + * greatest amount of precision when alu operations are mixed with jmp32 + * operations. These operations are BPF_ADD, BPF_SUB, BPF_MUL, BPF_ADD, + * and BPF_OR. This is possible because these ops have fairly easy to + * understand and calculate behavior in both 32-bit and 64-bit alu ops. + * See alu32 verifier tests for examples. The second class of + * operations, BPF_LSH, BPF_RSH, and BPF_ARSH, however are not so easy + * with regards to tracking sign/unsigned bounds because the bits may + * cross subreg boundaries in the alu64 case. When this happens we mark + * the reg unbounded in the subreg bound space and use the resulting + * tnum to calculate an approximation of the sign/unsigned bounds. + */ + switch (opcode) { + case BPF_ADD: + scalar32_min_max_add(dst_reg, &src_reg); + scalar_min_max_add(dst_reg, &src_reg); + dst_reg->var_off = tnum_add(dst_reg->var_off, src_reg.var_off); + break; + case BPF_SUB: + scalar32_min_max_sub(dst_reg, &src_reg); + scalar_min_max_sub(dst_reg, &src_reg); + dst_reg->var_off = tnum_sub(dst_reg->var_off, src_reg.var_off); + break; + case BPF_MUL: + dst_reg->var_off = tnum_mul(dst_reg->var_off, src_reg.var_off); + scalar32_min_max_mul(dst_reg, &src_reg); + scalar_min_max_mul(dst_reg, &src_reg); + break; + case BPF_AND: + dst_reg->var_off = tnum_and(dst_reg->var_off, src_reg.var_off); + scalar32_min_max_and(dst_reg, &src_reg); + scalar_min_max_and(dst_reg, &src_reg); + break; + case BPF_OR: + dst_reg->var_off = tnum_or(dst_reg->var_off, src_reg.var_off); + scalar32_min_max_or(dst_reg, &src_reg); + scalar_min_max_or(dst_reg, &src_reg); + break; + case BPF_XOR: + dst_reg->var_off = tnum_xor(dst_reg->var_off, src_reg.var_off); + scalar32_min_max_xor(dst_reg, &src_reg); + scalar_min_max_xor(dst_reg, &src_reg); + break; + case BPF_LSH: + if (umax_val >= insn_bitness) { + /* Shifts greater than 31 or 63 are undefined. + * This includes shifts by a negative number. + */ + mark_reg_unknown(env, regs, insn->dst_reg); + break; + } + if (alu32) + scalar32_min_max_lsh(dst_reg, &src_reg); + else + scalar_min_max_lsh(dst_reg, &src_reg); + break; + case BPF_RSH: + if (umax_val >= insn_bitness) { + /* Shifts greater than 31 or 63 are undefined. + * This includes shifts by a negative number. + */ + mark_reg_unknown(env, regs, insn->dst_reg); + break; + } + if (alu32) + scalar32_min_max_rsh(dst_reg, &src_reg); + else + scalar_min_max_rsh(dst_reg, &src_reg); + break; + case BPF_ARSH: + if (umax_val >= insn_bitness) { + /* Shifts greater than 31 or 63 are undefined. + * This includes shifts by a negative number. + */ + mark_reg_unknown(env, regs, insn->dst_reg); + break; + } + if (alu32) + scalar32_min_max_arsh(dst_reg, &src_reg); + else + scalar_min_max_arsh(dst_reg, &src_reg); + break; + default: + mark_reg_unknown(env, regs, insn->dst_reg); + break; + } + + /* ALU32 ops are zero extended into 64bit register */ + if (alu32) + zext_32_to_64(dst_reg); + reg_bounds_sync(dst_reg); + return 0; +} + +/* Handles ALU ops other than BPF_END, BPF_NEG and BPF_MOV: computes new min/max + * and var_off. + */ +static int adjust_reg_min_max_vals(struct bpf_verifier_env *env, + struct bpf_insn *insn) +{ + struct bpf_verifier_state *vstate = env->cur_state; + struct bpf_func_state *state = vstate->frame[vstate->curframe]; + struct bpf_reg_state *regs = state->regs, *dst_reg, *src_reg; + struct bpf_reg_state *ptr_reg = NULL, off_reg = {0}; + u8 opcode = BPF_OP(insn->code); + int err; + + dst_reg = ®s[insn->dst_reg]; + src_reg = NULL; + if (dst_reg->type != SCALAR_VALUE) + ptr_reg = dst_reg; + else + /* Make sure ID is cleared otherwise dst_reg min/max could be + * incorrectly propagated into other registers by find_equal_scalars() + */ + dst_reg->id = 0; + if (BPF_SRC(insn->code) == BPF_X) { + src_reg = ®s[insn->src_reg]; + if (src_reg->type != SCALAR_VALUE) { + if (dst_reg->type != SCALAR_VALUE) { + /* Combining two pointers by any ALU op yields + * an arbitrary scalar. Disallow all math except + * pointer subtraction + */ + if (opcode == BPF_SUB && env->allow_ptr_leaks) { + mark_reg_unknown(env, regs, insn->dst_reg); + return 0; + } + verbose(env, "R%d pointer %s pointer prohibited\n", + insn->dst_reg, + bpf_alu_string[opcode >> 4]); + return -EACCES; + } else { + /* scalar += pointer + * This is legal, but we have to reverse our + * src/dest handling in computing the range + */ + err = mark_chain_precision(env, insn->dst_reg); + if (err) + return err; + return adjust_ptr_min_max_vals(env, insn, + src_reg, dst_reg); + } + } else if (ptr_reg) { + /* pointer += scalar */ + err = mark_chain_precision(env, insn->src_reg); + if (err) + return err; + return adjust_ptr_min_max_vals(env, insn, + dst_reg, src_reg); + } else if (dst_reg->precise) { + /* if dst_reg is precise, src_reg should be precise as well */ + err = mark_chain_precision(env, insn->src_reg); + if (err) + return err; + } + } else { + /* Pretend the src is a reg with a known value, since we only + * need to be able to read from this state. + */ + off_reg.type = SCALAR_VALUE; + __mark_reg_known(&off_reg, insn->imm); + src_reg = &off_reg; + if (ptr_reg) /* pointer += K */ + return adjust_ptr_min_max_vals(env, insn, + ptr_reg, src_reg); + } + + /* Got here implies adding two SCALAR_VALUEs */ + if (WARN_ON_ONCE(ptr_reg)) { + print_verifier_state(env, state, true); + verbose(env, "verifier internal error: unexpected ptr_reg\n"); + return -EINVAL; + } + if (WARN_ON(!src_reg)) { + print_verifier_state(env, state, true); + verbose(env, "verifier internal error: no src_reg\n"); + return -EINVAL; + } + return adjust_scalar_min_max_vals(env, insn, dst_reg, *src_reg); +} + +/* check validity of 32-bit and 64-bit arithmetic operations */ +static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn) +{ + struct bpf_reg_state *regs = cur_regs(env); + u8 opcode = BPF_OP(insn->code); + int err; + + if (opcode == BPF_END || opcode == BPF_NEG) { + if (opcode == BPF_NEG) { + if (BPF_SRC(insn->code) != BPF_K || + insn->src_reg != BPF_REG_0 || + insn->off != 0 || insn->imm != 0) { + verbose(env, "BPF_NEG uses reserved fields\n"); + return -EINVAL; + } + } else { + if (insn->src_reg != BPF_REG_0 || insn->off != 0 || + (insn->imm != 16 && insn->imm != 32 && insn->imm != 64) || + (BPF_CLASS(insn->code) == BPF_ALU64 && + BPF_SRC(insn->code) != BPF_TO_LE)) { + verbose(env, "BPF_END uses reserved fields\n"); + return -EINVAL; + } + } + + /* check src operand */ + err = check_reg_arg(env, insn->dst_reg, SRC_OP); + if (err) + return err; + + if (is_pointer_value(env, insn->dst_reg)) { + verbose(env, "R%d pointer arithmetic prohibited\n", + insn->dst_reg); + return -EACCES; + } + + /* check dest operand */ + err = check_reg_arg(env, insn->dst_reg, DST_OP); + if (err) + return err; + + } else if (opcode == BPF_MOV) { + + if (BPF_SRC(insn->code) == BPF_X) { + if (insn->imm != 0) { + verbose(env, "BPF_MOV uses reserved fields\n"); + return -EINVAL; + } + + if (BPF_CLASS(insn->code) == BPF_ALU) { + if (insn->off != 0 && insn->off != 8 && insn->off != 16) { + verbose(env, "BPF_MOV uses reserved fields\n"); + return -EINVAL; + } + } else { + if (insn->off != 0 && insn->off != 8 && insn->off != 16 && + insn->off != 32) { + verbose(env, "BPF_MOV uses reserved fields\n"); + return -EINVAL; + } + } + + /* check src operand */ + err = check_reg_arg(env, insn->src_reg, SRC_OP); + if (err) + return err; + } else { + if (insn->src_reg != BPF_REG_0 || insn->off != 0) { + verbose(env, "BPF_MOV uses reserved fields\n"); + return -EINVAL; + } + } + + /* check dest operand, mark as required later */ + err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK); + if (err) + return err; + + if (BPF_SRC(insn->code) == BPF_X) { + struct bpf_reg_state *src_reg = regs + insn->src_reg; + struct bpf_reg_state *dst_reg = regs + insn->dst_reg; + bool need_id = src_reg->type == SCALAR_VALUE && !src_reg->id && + !tnum_is_const(src_reg->var_off); + + if (BPF_CLASS(insn->code) == BPF_ALU64) { + if (insn->off == 0) { + /* case: R1 = R2 + * copy register state to dest reg + */ + if (need_id) + /* Assign src and dst registers the same ID + * that will be used by find_equal_scalars() + * to propagate min/max range. + */ + src_reg->id = ++env->id_gen; + copy_register_state(dst_reg, src_reg); + dst_reg->live |= REG_LIVE_WRITTEN; + dst_reg->subreg_def = DEF_NOT_SUBREG; + } else { + /* case: R1 = (s8, s16 s32)R2 */ + if (is_pointer_value(env, insn->src_reg)) { + verbose(env, + "R%d sign-extension part of pointer\n", + insn->src_reg); + return -EACCES; + } else if (src_reg->type == SCALAR_VALUE) { + bool no_sext; + + no_sext = src_reg->umax_value < (1ULL << (insn->off - 1)); + if (no_sext && need_id) + src_reg->id = ++env->id_gen; + copy_register_state(dst_reg, src_reg); + if (!no_sext) + dst_reg->id = 0; + coerce_reg_to_size_sx(dst_reg, insn->off >> 3); + dst_reg->live |= REG_LIVE_WRITTEN; + dst_reg->subreg_def = DEF_NOT_SUBREG; + } else { + mark_reg_unknown(env, regs, insn->dst_reg); + } + } + } else { + /* R1 = (u32) R2 */ + if (is_pointer_value(env, insn->src_reg)) { + verbose(env, + "R%d partial copy of pointer\n", + insn->src_reg); + return -EACCES; + } else if (src_reg->type == SCALAR_VALUE) { + if (insn->off == 0) { + bool is_src_reg_u32 = src_reg->umax_value <= U32_MAX; + + if (is_src_reg_u32 && need_id) + src_reg->id = ++env->id_gen; + copy_register_state(dst_reg, src_reg); + /* Make sure ID is cleared if src_reg is not in u32 + * range otherwise dst_reg min/max could be incorrectly + * propagated into src_reg by find_equal_scalars() + */ + if (!is_src_reg_u32) + dst_reg->id = 0; + dst_reg->live |= REG_LIVE_WRITTEN; + dst_reg->subreg_def = env->insn_idx + 1; + } else { + /* case: W1 = (s8, s16)W2 */ + bool no_sext = src_reg->umax_value < (1ULL << (insn->off - 1)); + + if (no_sext && need_id) + src_reg->id = ++env->id_gen; + copy_register_state(dst_reg, src_reg); + if (!no_sext) + dst_reg->id = 0; + dst_reg->live |= REG_LIVE_WRITTEN; + dst_reg->subreg_def = env->insn_idx + 1; + coerce_subreg_to_size_sx(dst_reg, insn->off >> 3); + } + } else { + mark_reg_unknown(env, regs, + insn->dst_reg); + } + zext_32_to_64(dst_reg); + reg_bounds_sync(dst_reg); + } + } else { + /* case: R = imm + * remember the value we stored into this reg + */ + /* clear any state __mark_reg_known doesn't set */ + mark_reg_unknown(env, regs, insn->dst_reg); + regs[insn->dst_reg].type = SCALAR_VALUE; + if (BPF_CLASS(insn->code) == BPF_ALU64) { + __mark_reg_known(regs + insn->dst_reg, + insn->imm); + } else { + __mark_reg_known(regs + insn->dst_reg, + (u32)insn->imm); + } + } + + } else if (opcode > BPF_END) { + verbose(env, "invalid BPF_ALU opcode %x\n", opcode); + return -EINVAL; + + } else { /* all other ALU ops: and, sub, xor, add, ... */ + + if (BPF_SRC(insn->code) == BPF_X) { + if (insn->imm != 0 || insn->off > 1 || + (insn->off == 1 && opcode != BPF_MOD && opcode != BPF_DIV)) { + verbose(env, "BPF_ALU uses reserved fields\n"); + return -EINVAL; + } + /* check src1 operand */ + err = check_reg_arg(env, insn->src_reg, SRC_OP); + if (err) + return err; + } else { + if (insn->src_reg != BPF_REG_0 || insn->off > 1 || + (insn->off == 1 && opcode != BPF_MOD && opcode != BPF_DIV)) { + verbose(env, "BPF_ALU uses reserved fields\n"); + return -EINVAL; + } + } + + /* check src2 operand */ + err = check_reg_arg(env, insn->dst_reg, SRC_OP); + if (err) + return err; + + if ((opcode == BPF_MOD || opcode == BPF_DIV) && + BPF_SRC(insn->code) == BPF_K && insn->imm == 0) { + verbose(env, "div by zero\n"); + return -EINVAL; + } + + if ((opcode == BPF_LSH || opcode == BPF_RSH || + opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) { + int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32; + + if (insn->imm < 0 || insn->imm >= size) { + verbose(env, "invalid shift %d\n", insn->imm); + return -EINVAL; + } + } + + /* check dest operand */ + err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK); + if (err) + return err; + + return adjust_reg_min_max_vals(env, insn); + } + + return 0; +} + +static void find_good_pkt_pointers(struct bpf_verifier_state *vstate, + struct bpf_reg_state *dst_reg, + enum bpf_reg_type type, + bool range_right_open) +{ + struct bpf_func_state *state; + struct bpf_reg_state *reg; + int new_range; + + if (dst_reg->off < 0 || + (dst_reg->off == 0 && range_right_open)) + /* This doesn't give us any range */ + return; + + if (dst_reg->umax_value > MAX_PACKET_OFF || + dst_reg->umax_value + dst_reg->off > MAX_PACKET_OFF) + /* Risk of overflow. For instance, ptr + (1<<63) may be less + * than pkt_end, but that's because it's also less than pkt. + */ + return; + + new_range = dst_reg->off; + if (range_right_open) + new_range++; + + /* Examples for register markings: + * + * pkt_data in dst register: + * + * r2 = r3; + * r2 += 8; + * if (r2 > pkt_end) goto <handle exception> + * <access okay> + * + * r2 = r3; + * r2 += 8; + * if (r2 < pkt_end) goto <access okay> + * <handle exception> + * + * Where: + * r2 == dst_reg, pkt_end == src_reg + * r2=pkt(id=n,off=8,r=0) + * r3=pkt(id=n,off=0,r=0) + * + * pkt_data in src register: + * + * r2 = r3; + * r2 += 8; + * if (pkt_end >= r2) goto <access okay> + * <handle exception> + * + * r2 = r3; + * r2 += 8; + * if (pkt_end <= r2) goto <handle exception> + * <access okay> + * + * Where: + * pkt_end == dst_reg, r2 == src_reg + * r2=pkt(id=n,off=8,r=0) + * r3=pkt(id=n,off=0,r=0) + * + * Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8) + * or r3=pkt(id=n,off=0,r=8-1), so that range of bytes [r3, r3 + 8) + * and [r3, r3 + 8-1) respectively is safe to access depending on + * the check. + */ + + /* If our ids match, then we must have the same max_value. And we + * don't care about the other reg's fixed offset, since if it's too big + * the range won't allow anything. + * dst_reg->off is known < MAX_PACKET_OFF, therefore it fits in a u16. + */ + bpf_for_each_reg_in_vstate(vstate, state, reg, ({ + if (reg->type == type && reg->id == dst_reg->id) + /* keep the maximum range already checked */ + reg->range = max(reg->range, new_range); + })); +} + +static int is_branch32_taken(struct bpf_reg_state *reg, u32 val, u8 opcode) +{ + struct tnum subreg = tnum_subreg(reg->var_off); + s32 sval = (s32)val; + + switch (opcode) { + case BPF_JEQ: + if (tnum_is_const(subreg)) + return !!tnum_equals_const(subreg, val); + else if (val < reg->u32_min_value || val > reg->u32_max_value) + return 0; + break; + case BPF_JNE: + if (tnum_is_const(subreg)) + return !tnum_equals_const(subreg, val); + else if (val < reg->u32_min_value || val > reg->u32_max_value) + return 1; + break; + case BPF_JSET: + if ((~subreg.mask & subreg.value) & val) + return 1; + if (!((subreg.mask | subreg.value) & val)) + return 0; + break; + case BPF_JGT: + if (reg->u32_min_value > val) + return 1; + else if (reg->u32_max_value <= val) + return 0; + break; + case BPF_JSGT: + if (reg->s32_min_value > sval) + return 1; + else if (reg->s32_max_value <= sval) + return 0; + break; + case BPF_JLT: + if (reg->u32_max_value < val) + return 1; + else if (reg->u32_min_value >= val) + return 0; + break; + case BPF_JSLT: + if (reg->s32_max_value < sval) + return 1; + else if (reg->s32_min_value >= sval) + return 0; + break; + case BPF_JGE: + if (reg->u32_min_value >= val) + return 1; + else if (reg->u32_max_value < val) + return 0; + break; + case BPF_JSGE: + if (reg->s32_min_value >= sval) + return 1; + else if (reg->s32_max_value < sval) + return 0; + break; + case BPF_JLE: + if (reg->u32_max_value <= val) + return 1; + else if (reg->u32_min_value > val) + return 0; + break; + case BPF_JSLE: + if (reg->s32_max_value <= sval) + return 1; + else if (reg->s32_min_value > sval) + return 0; + break; + } + + return -1; +} + + +static int is_branch64_taken(struct bpf_reg_state *reg, u64 val, u8 opcode) +{ + s64 sval = (s64)val; + + switch (opcode) { + case BPF_JEQ: + if (tnum_is_const(reg->var_off)) + return !!tnum_equals_const(reg->var_off, val); + else if (val < reg->umin_value || val > reg->umax_value) + return 0; + break; + case BPF_JNE: + if (tnum_is_const(reg->var_off)) + return !tnum_equals_const(reg->var_off, val); + else if (val < reg->umin_value || val > reg->umax_value) + return 1; + break; + case BPF_JSET: + if ((~reg->var_off.mask & reg->var_off.value) & val) + return 1; + if (!((reg->var_off.mask | reg->var_off.value) & val)) + return 0; + break; + case BPF_JGT: + if (reg->umin_value > val) + return 1; + else if (reg->umax_value <= val) + return 0; + break; + case BPF_JSGT: + if (reg->smin_value > sval) + return 1; + else if (reg->smax_value <= sval) + return 0; + break; + case BPF_JLT: + if (reg->umax_value < val) + return 1; + else if (reg->umin_value >= val) + return 0; + break; + case BPF_JSLT: + if (reg->smax_value < sval) + return 1; + else if (reg->smin_value >= sval) + return 0; + break; + case BPF_JGE: + if (reg->umin_value >= val) + return 1; + else if (reg->umax_value < val) + return 0; + break; + case BPF_JSGE: + if (reg->smin_value >= sval) + return 1; + else if (reg->smax_value < sval) + return 0; + break; + case BPF_JLE: + if (reg->umax_value <= val) + return 1; + else if (reg->umin_value > val) + return 0; + break; + case BPF_JSLE: + if (reg->smax_value <= sval) + return 1; + else if (reg->smin_value > sval) + return 0; + break; + } + + return -1; +} + +/* compute branch direction of the expression "if (reg opcode val) goto target;" + * and return: + * 1 - branch will be taken and "goto target" will be executed + * 0 - branch will not be taken and fall-through to next insn + * -1 - unknown. Example: "if (reg < 5)" is unknown when register value + * range [0,10] + */ +static int is_branch_taken(struct bpf_reg_state *reg, u64 val, u8 opcode, + bool is_jmp32) +{ + if (__is_pointer_value(false, reg)) { + if (!reg_not_null(reg)) + return -1; + + /* If pointer is valid tests against zero will fail so we can + * use this to direct branch taken. + */ + if (val != 0) + return -1; + + switch (opcode) { + case BPF_JEQ: + return 0; + case BPF_JNE: + return 1; + default: + return -1; + } + } + + if (is_jmp32) + return is_branch32_taken(reg, val, opcode); + return is_branch64_taken(reg, val, opcode); +} + +static int flip_opcode(u32 opcode) +{ + /* How can we transform "a <op> b" into "b <op> a"? */ + static const u8 opcode_flip[16] = { + /* these stay the same */ + [BPF_JEQ >> 4] = BPF_JEQ, + [BPF_JNE >> 4] = BPF_JNE, + [BPF_JSET >> 4] = BPF_JSET, + /* these swap "lesser" and "greater" (L and G in the opcodes) */ + [BPF_JGE >> 4] = BPF_JLE, + [BPF_JGT >> 4] = BPF_JLT, + [BPF_JLE >> 4] = BPF_JGE, + [BPF_JLT >> 4] = BPF_JGT, + [BPF_JSGE >> 4] = BPF_JSLE, + [BPF_JSGT >> 4] = BPF_JSLT, + [BPF_JSLE >> 4] = BPF_JSGE, + [BPF_JSLT >> 4] = BPF_JSGT + }; + return opcode_flip[opcode >> 4]; +} + +static int is_pkt_ptr_branch_taken(struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg, + u8 opcode) +{ + struct bpf_reg_state *pkt; + + if (src_reg->type == PTR_TO_PACKET_END) { + pkt = dst_reg; + } else if (dst_reg->type == PTR_TO_PACKET_END) { + pkt = src_reg; + opcode = flip_opcode(opcode); + } else { + return -1; + } + + if (pkt->range >= 0) + return -1; + + switch (opcode) { + case BPF_JLE: + /* pkt <= pkt_end */ + fallthrough; + case BPF_JGT: + /* pkt > pkt_end */ + if (pkt->range == BEYOND_PKT_END) + /* pkt has at last one extra byte beyond pkt_end */ + return opcode == BPF_JGT; + break; + case BPF_JLT: + /* pkt < pkt_end */ + fallthrough; + case BPF_JGE: + /* pkt >= pkt_end */ + if (pkt->range == BEYOND_PKT_END || pkt->range == AT_PKT_END) + return opcode == BPF_JGE; + break; + } + return -1; +} + +/* Adjusts the register min/max values in the case that the dst_reg is the + * variable register that we are working on, and src_reg is a constant or we're + * simply doing a BPF_K check. + * In JEQ/JNE cases we also adjust the var_off values. + */ +static void reg_set_min_max(struct bpf_reg_state *true_reg, + struct bpf_reg_state *false_reg, + u64 val, u32 val32, + u8 opcode, bool is_jmp32) +{ + struct tnum false_32off = tnum_subreg(false_reg->var_off); + struct tnum false_64off = false_reg->var_off; + struct tnum true_32off = tnum_subreg(true_reg->var_off); + struct tnum true_64off = true_reg->var_off; + s64 sval = (s64)val; + s32 sval32 = (s32)val32; + + /* If the dst_reg is a pointer, we can't learn anything about its + * variable offset from the compare (unless src_reg were a pointer into + * the same object, but we don't bother with that. + * Since false_reg and true_reg have the same type by construction, we + * only need to check one of them for pointerness. + */ + if (__is_pointer_value(false, false_reg)) + return; + + switch (opcode) { + /* JEQ/JNE comparison doesn't change the register equivalence. + * + * r1 = r2; + * if (r1 == 42) goto label; + * ... + * label: // here both r1 and r2 are known to be 42. + * + * Hence when marking register as known preserve it's ID. + */ + case BPF_JEQ: + if (is_jmp32) { + __mark_reg32_known(true_reg, val32); + true_32off = tnum_subreg(true_reg->var_off); + } else { + ___mark_reg_known(true_reg, val); + true_64off = true_reg->var_off; + } + break; + case BPF_JNE: + if (is_jmp32) { + __mark_reg32_known(false_reg, val32); + false_32off = tnum_subreg(false_reg->var_off); + } else { + ___mark_reg_known(false_reg, val); + false_64off = false_reg->var_off; + } + break; + case BPF_JSET: + if (is_jmp32) { + false_32off = tnum_and(false_32off, tnum_const(~val32)); + if (is_power_of_2(val32)) + true_32off = tnum_or(true_32off, + tnum_const(val32)); + } else { + false_64off = tnum_and(false_64off, tnum_const(~val)); + if (is_power_of_2(val)) + true_64off = tnum_or(true_64off, + tnum_const(val)); + } + break; + case BPF_JGE: + case BPF_JGT: + { + if (is_jmp32) { + u32 false_umax = opcode == BPF_JGT ? val32 : val32 - 1; + u32 true_umin = opcode == BPF_JGT ? val32 + 1 : val32; + + false_reg->u32_max_value = min(false_reg->u32_max_value, + false_umax); + true_reg->u32_min_value = max(true_reg->u32_min_value, + true_umin); + } else { + u64 false_umax = opcode == BPF_JGT ? val : val - 1; + u64 true_umin = opcode == BPF_JGT ? val + 1 : val; + + false_reg->umax_value = min(false_reg->umax_value, false_umax); + true_reg->umin_value = max(true_reg->umin_value, true_umin); + } + break; + } + case BPF_JSGE: + case BPF_JSGT: + { + if (is_jmp32) { + s32 false_smax = opcode == BPF_JSGT ? sval32 : sval32 - 1; + s32 true_smin = opcode == BPF_JSGT ? sval32 + 1 : sval32; + + false_reg->s32_max_value = min(false_reg->s32_max_value, false_smax); + true_reg->s32_min_value = max(true_reg->s32_min_value, true_smin); + } else { + s64 false_smax = opcode == BPF_JSGT ? sval : sval - 1; + s64 true_smin = opcode == BPF_JSGT ? sval + 1 : sval; + + false_reg->smax_value = min(false_reg->smax_value, false_smax); + true_reg->smin_value = max(true_reg->smin_value, true_smin); + } + break; + } + case BPF_JLE: + case BPF_JLT: + { + if (is_jmp32) { + u32 false_umin = opcode == BPF_JLT ? val32 : val32 + 1; + u32 true_umax = opcode == BPF_JLT ? val32 - 1 : val32; + + false_reg->u32_min_value = max(false_reg->u32_min_value, + false_umin); + true_reg->u32_max_value = min(true_reg->u32_max_value, + true_umax); + } else { + u64 false_umin = opcode == BPF_JLT ? val : val + 1; + u64 true_umax = opcode == BPF_JLT ? val - 1 : val; + + false_reg->umin_value = max(false_reg->umin_value, false_umin); + true_reg->umax_value = min(true_reg->umax_value, true_umax); + } + break; + } + case BPF_JSLE: + case BPF_JSLT: + { + if (is_jmp32) { + s32 false_smin = opcode == BPF_JSLT ? sval32 : sval32 + 1; + s32 true_smax = opcode == BPF_JSLT ? sval32 - 1 : sval32; + + false_reg->s32_min_value = max(false_reg->s32_min_value, false_smin); + true_reg->s32_max_value = min(true_reg->s32_max_value, true_smax); + } else { + s64 false_smin = opcode == BPF_JSLT ? sval : sval + 1; + s64 true_smax = opcode == BPF_JSLT ? sval - 1 : sval; + + false_reg->smin_value = max(false_reg->smin_value, false_smin); + true_reg->smax_value = min(true_reg->smax_value, true_smax); + } + break; + } + default: + return; + } + + if (is_jmp32) { + false_reg->var_off = tnum_or(tnum_clear_subreg(false_64off), + tnum_subreg(false_32off)); + true_reg->var_off = tnum_or(tnum_clear_subreg(true_64off), + tnum_subreg(true_32off)); + __reg_combine_32_into_64(false_reg); + __reg_combine_32_into_64(true_reg); + } else { + false_reg->var_off = false_64off; + true_reg->var_off = true_64off; + __reg_combine_64_into_32(false_reg); + __reg_combine_64_into_32(true_reg); + } +} + +/* Same as above, but for the case that dst_reg holds a constant and src_reg is + * the variable reg. + */ +static void reg_set_min_max_inv(struct bpf_reg_state *true_reg, + struct bpf_reg_state *false_reg, + u64 val, u32 val32, + u8 opcode, bool is_jmp32) +{ + opcode = flip_opcode(opcode); + /* This uses zero as "not present in table"; luckily the zero opcode, + * BPF_JA, can't get here. + */ + if (opcode) + reg_set_min_max(true_reg, false_reg, val, val32, opcode, is_jmp32); +} + +/* Regs are known to be equal, so intersect their min/max/var_off */ +static void __reg_combine_min_max(struct bpf_reg_state *src_reg, + struct bpf_reg_state *dst_reg) +{ + src_reg->umin_value = dst_reg->umin_value = max(src_reg->umin_value, + dst_reg->umin_value); + src_reg->umax_value = dst_reg->umax_value = min(src_reg->umax_value, + dst_reg->umax_value); + src_reg->smin_value = dst_reg->smin_value = max(src_reg->smin_value, + dst_reg->smin_value); + src_reg->smax_value = dst_reg->smax_value = min(src_reg->smax_value, + dst_reg->smax_value); + src_reg->var_off = dst_reg->var_off = tnum_intersect(src_reg->var_off, + dst_reg->var_off); + reg_bounds_sync(src_reg); + reg_bounds_sync(dst_reg); +} + +static void reg_combine_min_max(struct bpf_reg_state *true_src, + struct bpf_reg_state *true_dst, + struct bpf_reg_state *false_src, + struct bpf_reg_state *false_dst, + u8 opcode) +{ + switch (opcode) { + case BPF_JEQ: + __reg_combine_min_max(true_src, true_dst); + break; + case BPF_JNE: + __reg_combine_min_max(false_src, false_dst); + break; + } +} + +static void mark_ptr_or_null_reg(struct bpf_func_state *state, + struct bpf_reg_state *reg, u32 id, + bool is_null) +{ + if (type_may_be_null(reg->type) && reg->id == id && + (is_rcu_reg(reg) || !WARN_ON_ONCE(!reg->id))) { + /* Old offset (both fixed and variable parts) should have been + * known-zero, because we don't allow pointer arithmetic on + * pointers that might be NULL. If we see this happening, don't + * convert the register. + * + * But in some cases, some helpers that return local kptrs + * advance offset for the returned pointer. In those cases, it + * is fine to expect to see reg->off. + */ + if (WARN_ON_ONCE(reg->smin_value || reg->smax_value || !tnum_equals_const(reg->var_off, 0))) + return; + if (!(type_is_ptr_alloc_obj(reg->type) || type_is_non_owning_ref(reg->type)) && + WARN_ON_ONCE(reg->off)) + return; + + if (is_null) { + reg->type = SCALAR_VALUE; + /* We don't need id and ref_obj_id from this point + * onwards anymore, thus we should better reset it, + * so that state pruning has chances to take effect. + */ + reg->id = 0; + reg->ref_obj_id = 0; + + return; + } + + mark_ptr_not_null_reg(reg); + + if (!reg_may_point_to_spin_lock(reg)) { + /* For not-NULL ptr, reg->ref_obj_id will be reset + * in release_reference(). + * + * reg->id is still used by spin_lock ptr. Other + * than spin_lock ptr type, reg->id can be reset. + */ + reg->id = 0; + } + } +} + +/* The logic is similar to find_good_pkt_pointers(), both could eventually + * be folded together at some point. + */ +static void mark_ptr_or_null_regs(struct bpf_verifier_state *vstate, u32 regno, + bool is_null) +{ + struct bpf_func_state *state = vstate->frame[vstate->curframe]; + struct bpf_reg_state *regs = state->regs, *reg; + u32 ref_obj_id = regs[regno].ref_obj_id; + u32 id = regs[regno].id; + + if (ref_obj_id && ref_obj_id == id && is_null) + /* regs[regno] is in the " == NULL" branch. + * No one could have freed the reference state before + * doing the NULL check. + */ + WARN_ON_ONCE(release_reference_state(state, id)); + + bpf_for_each_reg_in_vstate(vstate, state, reg, ({ + mark_ptr_or_null_reg(state, reg, id, is_null); + })); +} + +static bool try_match_pkt_pointers(const struct bpf_insn *insn, + struct bpf_reg_state *dst_reg, + struct bpf_reg_state *src_reg, + struct bpf_verifier_state *this_branch, + struct bpf_verifier_state *other_branch) +{ + if (BPF_SRC(insn->code) != BPF_X) + return false; + + /* Pointers are always 64-bit. */ + if (BPF_CLASS(insn->code) == BPF_JMP32) + return false; + + switch (BPF_OP(insn->code)) { + case BPF_JGT: + if ((dst_reg->type == PTR_TO_PACKET && + src_reg->type == PTR_TO_PACKET_END) || + (dst_reg->type == PTR_TO_PACKET_META && + reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) { + /* pkt_data' > pkt_end, pkt_meta' > pkt_data */ + find_good_pkt_pointers(this_branch, dst_reg, + dst_reg->type, false); + mark_pkt_end(other_branch, insn->dst_reg, true); + } else if ((dst_reg->type == PTR_TO_PACKET_END && + src_reg->type == PTR_TO_PACKET) || + (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && + src_reg->type == PTR_TO_PACKET_META)) { + /* pkt_end > pkt_data', pkt_data > pkt_meta' */ + find_good_pkt_pointers(other_branch, src_reg, + src_reg->type, true); + mark_pkt_end(this_branch, insn->src_reg, false); + } else { + return false; + } + break; + case BPF_JLT: + if ((dst_reg->type == PTR_TO_PACKET && + src_reg->type == PTR_TO_PACKET_END) || + (dst_reg->type == PTR_TO_PACKET_META && + reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) { + /* pkt_data' < pkt_end, pkt_meta' < pkt_data */ + find_good_pkt_pointers(other_branch, dst_reg, + dst_reg->type, true); + mark_pkt_end(this_branch, insn->dst_reg, false); + } else if ((dst_reg->type == PTR_TO_PACKET_END && + src_reg->type == PTR_TO_PACKET) || + (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && + src_reg->type == PTR_TO_PACKET_META)) { + /* pkt_end < pkt_data', pkt_data > pkt_meta' */ + find_good_pkt_pointers(this_branch, src_reg, + src_reg->type, false); + mark_pkt_end(other_branch, insn->src_reg, true); + } else { + return false; + } + break; + case BPF_JGE: + if ((dst_reg->type == PTR_TO_PACKET && + src_reg->type == PTR_TO_PACKET_END) || + (dst_reg->type == PTR_TO_PACKET_META && + reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) { + /* pkt_data' >= pkt_end, pkt_meta' >= pkt_data */ + find_good_pkt_pointers(this_branch, dst_reg, + dst_reg->type, true); + mark_pkt_end(other_branch, insn->dst_reg, false); + } else if ((dst_reg->type == PTR_TO_PACKET_END && + src_reg->type == PTR_TO_PACKET) || + (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && + src_reg->type == PTR_TO_PACKET_META)) { + /* pkt_end >= pkt_data', pkt_data >= pkt_meta' */ + find_good_pkt_pointers(other_branch, src_reg, + src_reg->type, false); + mark_pkt_end(this_branch, insn->src_reg, true); + } else { + return false; + } + break; + case BPF_JLE: + if ((dst_reg->type == PTR_TO_PACKET && + src_reg->type == PTR_TO_PACKET_END) || + (dst_reg->type == PTR_TO_PACKET_META && + reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) { + /* pkt_data' <= pkt_end, pkt_meta' <= pkt_data */ + find_good_pkt_pointers(other_branch, dst_reg, + dst_reg->type, false); + mark_pkt_end(this_branch, insn->dst_reg, true); + } else if ((dst_reg->type == PTR_TO_PACKET_END && + src_reg->type == PTR_TO_PACKET) || + (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && + src_reg->type == PTR_TO_PACKET_META)) { + /* pkt_end <= pkt_data', pkt_data <= pkt_meta' */ + find_good_pkt_pointers(this_branch, src_reg, + src_reg->type, true); + mark_pkt_end(other_branch, insn->src_reg, false); + } else { + return false; + } + break; + default: + return false; + } + + return true; +} + +static void find_equal_scalars(struct bpf_verifier_state *vstate, + struct bpf_reg_state *known_reg) +{ + struct bpf_func_state *state; + struct bpf_reg_state *reg; + + bpf_for_each_reg_in_vstate(vstate, state, reg, ({ + if (reg->type == SCALAR_VALUE && reg->id == known_reg->id) + copy_register_state(reg, known_reg); + })); +} + +static int check_cond_jmp_op(struct bpf_verifier_env *env, + struct bpf_insn *insn, int *insn_idx) +{ + struct bpf_verifier_state *this_branch = env->cur_state; + struct bpf_verifier_state *other_branch; + struct bpf_reg_state *regs = this_branch->frame[this_branch->curframe]->regs; + struct bpf_reg_state *dst_reg, *other_branch_regs, *src_reg = NULL; + struct bpf_reg_state *eq_branch_regs; + u8 opcode = BPF_OP(insn->code); + bool is_jmp32; + int pred = -1; + int err; + + /* Only conditional jumps are expected to reach here. */ + if (opcode == BPF_JA || opcode > BPF_JSLE) { + verbose(env, "invalid BPF_JMP/JMP32 opcode %x\n", opcode); + return -EINVAL; + } + + /* check src2 operand */ + err = check_reg_arg(env, insn->dst_reg, SRC_OP); + if (err) + return err; + + dst_reg = ®s[insn->dst_reg]; + if (BPF_SRC(insn->code) == BPF_X) { + if (insn->imm != 0) { + verbose(env, "BPF_JMP/JMP32 uses reserved fields\n"); + return -EINVAL; + } + + /* check src1 operand */ + err = check_reg_arg(env, insn->src_reg, SRC_OP); + if (err) + return err; + + src_reg = ®s[insn->src_reg]; + if (!(reg_is_pkt_pointer_any(dst_reg) && reg_is_pkt_pointer_any(src_reg)) && + is_pointer_value(env, insn->src_reg)) { + verbose(env, "R%d pointer comparison prohibited\n", + insn->src_reg); + return -EACCES; + } + } else { + if (insn->src_reg != BPF_REG_0) { + verbose(env, "BPF_JMP/JMP32 uses reserved fields\n"); + return -EINVAL; + } + } + + is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32; + + if (BPF_SRC(insn->code) == BPF_K) { + pred = is_branch_taken(dst_reg, insn->imm, opcode, is_jmp32); + } else if (src_reg->type == SCALAR_VALUE && + is_jmp32 && tnum_is_const(tnum_subreg(src_reg->var_off))) { + pred = is_branch_taken(dst_reg, + tnum_subreg(src_reg->var_off).value, + opcode, + is_jmp32); + } else if (src_reg->type == SCALAR_VALUE && + !is_jmp32 && tnum_is_const(src_reg->var_off)) { + pred = is_branch_taken(dst_reg, + src_reg->var_off.value, + opcode, + is_jmp32); + } else if (dst_reg->type == SCALAR_VALUE && + is_jmp32 && tnum_is_const(tnum_subreg(dst_reg->var_off))) { + pred = is_branch_taken(src_reg, + tnum_subreg(dst_reg->var_off).value, + flip_opcode(opcode), + is_jmp32); + } else if (dst_reg->type == SCALAR_VALUE && + !is_jmp32 && tnum_is_const(dst_reg->var_off)) { + pred = is_branch_taken(src_reg, + dst_reg->var_off.value, + flip_opcode(opcode), + is_jmp32); + } else if (reg_is_pkt_pointer_any(dst_reg) && + reg_is_pkt_pointer_any(src_reg) && + !is_jmp32) { + pred = is_pkt_ptr_branch_taken(dst_reg, src_reg, opcode); + } + + if (pred >= 0) { + /* If we get here with a dst_reg pointer type it is because + * above is_branch_taken() special cased the 0 comparison. + */ + if (!__is_pointer_value(false, dst_reg)) + err = mark_chain_precision(env, insn->dst_reg); + if (BPF_SRC(insn->code) == BPF_X && !err && + !__is_pointer_value(false, src_reg)) + err = mark_chain_precision(env, insn->src_reg); + if (err) + return err; + } + + if (pred == 1) { + /* Only follow the goto, ignore fall-through. If needed, push + * the fall-through branch for simulation under speculative + * execution. + */ + if (!env->bypass_spec_v1 && + !sanitize_speculative_path(env, insn, *insn_idx + 1, + *insn_idx)) + return -EFAULT; + if (env->log.level & BPF_LOG_LEVEL) + print_insn_state(env, this_branch->frame[this_branch->curframe]); + *insn_idx += insn->off; + return 0; + } else if (pred == 0) { + /* Only follow the fall-through branch, since that's where the + * program will go. If needed, push the goto branch for + * simulation under speculative execution. + */ + if (!env->bypass_spec_v1 && + !sanitize_speculative_path(env, insn, + *insn_idx + insn->off + 1, + *insn_idx)) + return -EFAULT; + if (env->log.level & BPF_LOG_LEVEL) + print_insn_state(env, this_branch->frame[this_branch->curframe]); + return 0; + } + + other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx, + false); + if (!other_branch) + return -EFAULT; + other_branch_regs = other_branch->frame[other_branch->curframe]->regs; + + /* detect if we are comparing against a constant value so we can adjust + * our min/max values for our dst register. + * this is only legit if both are scalars (or pointers to the same + * object, I suppose, see the PTR_MAYBE_NULL related if block below), + * because otherwise the different base pointers mean the offsets aren't + * comparable. + */ + if (BPF_SRC(insn->code) == BPF_X) { + struct bpf_reg_state *src_reg = ®s[insn->src_reg]; + + if (dst_reg->type == SCALAR_VALUE && + src_reg->type == SCALAR_VALUE) { + if (tnum_is_const(src_reg->var_off) || + (is_jmp32 && + tnum_is_const(tnum_subreg(src_reg->var_off)))) + reg_set_min_max(&other_branch_regs[insn->dst_reg], + dst_reg, + src_reg->var_off.value, + tnum_subreg(src_reg->var_off).value, + opcode, is_jmp32); + else if (tnum_is_const(dst_reg->var_off) || + (is_jmp32 && + tnum_is_const(tnum_subreg(dst_reg->var_off)))) + reg_set_min_max_inv(&other_branch_regs[insn->src_reg], + src_reg, + dst_reg->var_off.value, + tnum_subreg(dst_reg->var_off).value, + opcode, is_jmp32); + else if (!is_jmp32 && + (opcode == BPF_JEQ || opcode == BPF_JNE)) + /* Comparing for equality, we can combine knowledge */ + reg_combine_min_max(&other_branch_regs[insn->src_reg], + &other_branch_regs[insn->dst_reg], + src_reg, dst_reg, opcode); + if (src_reg->id && + !WARN_ON_ONCE(src_reg->id != other_branch_regs[insn->src_reg].id)) { + find_equal_scalars(this_branch, src_reg); + find_equal_scalars(other_branch, &other_branch_regs[insn->src_reg]); + } + + } + } else if (dst_reg->type == SCALAR_VALUE) { + reg_set_min_max(&other_branch_regs[insn->dst_reg], + dst_reg, insn->imm, (u32)insn->imm, + opcode, is_jmp32); + } + + if (dst_reg->type == SCALAR_VALUE && dst_reg->id && + !WARN_ON_ONCE(dst_reg->id != other_branch_regs[insn->dst_reg].id)) { + find_equal_scalars(this_branch, dst_reg); + find_equal_scalars(other_branch, &other_branch_regs[insn->dst_reg]); + } + + /* if one pointer register is compared to another pointer + * register check if PTR_MAYBE_NULL could be lifted. + * E.g. register A - maybe null + * register B - not null + * for JNE A, B, ... - A is not null in the false branch; + * for JEQ A, B, ... - A is not null in the true branch. + * + * Since PTR_TO_BTF_ID points to a kernel struct that does + * not need to be null checked by the BPF program, i.e., + * could be null even without PTR_MAYBE_NULL marking, so + * only propagate nullness when neither reg is that type. + */ + if (!is_jmp32 && BPF_SRC(insn->code) == BPF_X && + __is_pointer_value(false, src_reg) && __is_pointer_value(false, dst_reg) && + type_may_be_null(src_reg->type) != type_may_be_null(dst_reg->type) && + base_type(src_reg->type) != PTR_TO_BTF_ID && + base_type(dst_reg->type) != PTR_TO_BTF_ID) { + eq_branch_regs = NULL; + switch (opcode) { + case BPF_JEQ: + eq_branch_regs = other_branch_regs; + break; + case BPF_JNE: + eq_branch_regs = regs; + break; + default: + /* do nothing */ + break; + } + if (eq_branch_regs) { + if (type_may_be_null(src_reg->type)) + mark_ptr_not_null_reg(&eq_branch_regs[insn->src_reg]); + else + mark_ptr_not_null_reg(&eq_branch_regs[insn->dst_reg]); + } + } + + /* detect if R == 0 where R is returned from bpf_map_lookup_elem(). + * NOTE: these optimizations below are related with pointer comparison + * which will never be JMP32. + */ + if (!is_jmp32 && BPF_SRC(insn->code) == BPF_K && + insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) && + type_may_be_null(dst_reg->type)) { + /* Mark all identical registers in each branch as either + * safe or unknown depending R == 0 or R != 0 conditional. + */ + mark_ptr_or_null_regs(this_branch, insn->dst_reg, + opcode == BPF_JNE); + mark_ptr_or_null_regs(other_branch, insn->dst_reg, + opcode == BPF_JEQ); + } else if (!try_match_pkt_pointers(insn, dst_reg, ®s[insn->src_reg], + this_branch, other_branch) && + is_pointer_value(env, insn->dst_reg)) { + verbose(env, "R%d pointer comparison prohibited\n", + insn->dst_reg); + return -EACCES; + } + if (env->log.level & BPF_LOG_LEVEL) + print_insn_state(env, this_branch->frame[this_branch->curframe]); + return 0; +} + +/* verify BPF_LD_IMM64 instruction */ +static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn) +{ + struct bpf_insn_aux_data *aux = cur_aux(env); + struct bpf_reg_state *regs = cur_regs(env); + struct bpf_reg_state *dst_reg; + struct bpf_map *map; + int err; + + if (BPF_SIZE(insn->code) != BPF_DW) { + verbose(env, "invalid BPF_LD_IMM insn\n"); + return -EINVAL; + } + if (insn->off != 0) { + verbose(env, "BPF_LD_IMM64 uses reserved fields\n"); + return -EINVAL; + } + + err = check_reg_arg(env, insn->dst_reg, DST_OP); + if (err) + return err; + + dst_reg = ®s[insn->dst_reg]; + if (insn->src_reg == 0) { + u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm; + + dst_reg->type = SCALAR_VALUE; + __mark_reg_known(®s[insn->dst_reg], imm); + return 0; + } + + /* All special src_reg cases are listed below. From this point onwards + * we either succeed and assign a corresponding dst_reg->type after + * zeroing the offset, or fail and reject the program. + */ + mark_reg_known_zero(env, regs, insn->dst_reg); + + if (insn->src_reg == BPF_PSEUDO_BTF_ID) { + dst_reg->type = aux->btf_var.reg_type; + switch (base_type(dst_reg->type)) { + case PTR_TO_MEM: + dst_reg->mem_size = aux->btf_var.mem_size; + break; + case PTR_TO_BTF_ID: + dst_reg->btf = aux->btf_var.btf; + dst_reg->btf_id = aux->btf_var.btf_id; + break; + default: + verbose(env, "bpf verifier is misconfigured\n"); + return -EFAULT; + } + return 0; + } + + if (insn->src_reg == BPF_PSEUDO_FUNC) { + struct bpf_prog_aux *aux = env->prog->aux; + u32 subprogno = find_subprog(env, + env->insn_idx + insn->imm + 1); + + if (!aux->func_info) { + verbose(env, "missing btf func_info\n"); + return -EINVAL; + } + if (aux->func_info_aux[subprogno].linkage != BTF_FUNC_STATIC) { + verbose(env, "callback function not static\n"); + return -EINVAL; + } + + dst_reg->type = PTR_TO_FUNC; + dst_reg->subprogno = subprogno; + return 0; + } + + map = env->used_maps[aux->map_index]; + dst_reg->map_ptr = map; + + if (insn->src_reg == BPF_PSEUDO_MAP_VALUE || + insn->src_reg == BPF_PSEUDO_MAP_IDX_VALUE) { + dst_reg->type = PTR_TO_MAP_VALUE; + dst_reg->off = aux->map_off; + WARN_ON_ONCE(map->max_entries != 1); + /* We want reg->id to be same (0) as map_value is not distinct */ + } else if (insn->src_reg == BPF_PSEUDO_MAP_FD || + insn->src_reg == BPF_PSEUDO_MAP_IDX) { + dst_reg->type = CONST_PTR_TO_MAP; + } else { + verbose(env, "bpf verifier is misconfigured\n"); + return -EINVAL; + } + + return 0; +} + +static bool may_access_skb(enum bpf_prog_type type) +{ + switch (type) { + case BPF_PROG_TYPE_SOCKET_FILTER: + case BPF_PROG_TYPE_SCHED_CLS: + case BPF_PROG_TYPE_SCHED_ACT: + return true; + default: + return false; + } +} + +/* verify safety of LD_ABS|LD_IND instructions: + * - they can only appear in the programs where ctx == skb + * - since they are wrappers of function calls, they scratch R1-R5 registers, + * preserve R6-R9, and store return value into R0 + * + * Implicit input: + * ctx == skb == R6 == CTX + * + * Explicit input: + * SRC == any register + * IMM == 32-bit immediate + * + * Output: + * R0 - 8/16/32-bit skb data converted to cpu endianness + */ +static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn) +{ + struct bpf_reg_state *regs = cur_regs(env); + static const int ctx_reg = BPF_REG_6; + u8 mode = BPF_MODE(insn->code); + int i, err; + + if (!may_access_skb(resolve_prog_type(env->prog))) { + verbose(env, "BPF_LD_[ABS|IND] instructions not allowed for this program type\n"); + return -EINVAL; + } + + if (!env->ops->gen_ld_abs) { + verbose(env, "bpf verifier is misconfigured\n"); + return -EINVAL; + } + + if (insn->dst_reg != BPF_REG_0 || insn->off != 0 || + BPF_SIZE(insn->code) == BPF_DW || + (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) { + verbose(env, "BPF_LD_[ABS|IND] uses reserved fields\n"); + return -EINVAL; + } + + /* check whether implicit source operand (register R6) is readable */ + err = check_reg_arg(env, ctx_reg, SRC_OP); + if (err) + return err; + + /* Disallow usage of BPF_LD_[ABS|IND] with reference tracking, as + * gen_ld_abs() may terminate the program at runtime, leading to + * reference leak. + */ + err = check_reference_leak(env); + if (err) { + verbose(env, "BPF_LD_[ABS|IND] cannot be mixed with socket references\n"); + return err; + } + + if (env->cur_state->active_lock.ptr) { + verbose(env, "BPF_LD_[ABS|IND] cannot be used inside bpf_spin_lock-ed region\n"); + return -EINVAL; + } + + if (env->cur_state->active_rcu_lock) { + verbose(env, "BPF_LD_[ABS|IND] cannot be used inside bpf_rcu_read_lock-ed region\n"); + return -EINVAL; + } + + if (regs[ctx_reg].type != PTR_TO_CTX) { + verbose(env, + "at the time of BPF_LD_ABS|IND R6 != pointer to skb\n"); + return -EINVAL; + } + + if (mode == BPF_IND) { + /* check explicit source operand */ + err = check_reg_arg(env, insn->src_reg, SRC_OP); + if (err) + return err; + } + + err = check_ptr_off_reg(env, ®s[ctx_reg], ctx_reg); + if (err < 0) + return err; + + /* reset caller saved regs to unreadable */ + for (i = 0; i < CALLER_SAVED_REGS; i++) { + mark_reg_not_init(env, regs, caller_saved[i]); + check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK); + } + + /* mark destination R0 register as readable, since it contains + * the value fetched from the packet. + * Already marked as written above. + */ + mark_reg_unknown(env, regs, BPF_REG_0); + /* ld_abs load up to 32-bit skb data. */ + regs[BPF_REG_0].subreg_def = env->insn_idx + 1; + return 0; +} + +static int check_return_code(struct bpf_verifier_env *env) +{ + struct tnum enforce_attach_type_range = tnum_unknown; + const struct bpf_prog *prog = env->prog; + struct bpf_reg_state *reg; + struct tnum range = tnum_range(0, 1), const_0 = tnum_const(0); + enum bpf_prog_type prog_type = resolve_prog_type(env->prog); + int err; + struct bpf_func_state *frame = env->cur_state->frame[0]; + const bool is_subprog = frame->subprogno; + + /* LSM and struct_ops func-ptr's return type could be "void" */ + if (!is_subprog) { + switch (prog_type) { + case BPF_PROG_TYPE_LSM: + if (prog->expected_attach_type == BPF_LSM_CGROUP) + /* See below, can be 0 or 0-1 depending on hook. */ + break; + fallthrough; + case BPF_PROG_TYPE_STRUCT_OPS: + if (!prog->aux->attach_func_proto->type) + return 0; + break; + default: + break; + } + } + + /* eBPF calling convention is such that R0 is used + * to return the value from eBPF program. + * Make sure that it's readable at this time + * of bpf_exit, which means that program wrote + * something into it earlier + */ + err = check_reg_arg(env, BPF_REG_0, SRC_OP); + if (err) + return err; + + if (is_pointer_value(env, BPF_REG_0)) { + verbose(env, "R0 leaks addr as return value\n"); + return -EACCES; + } + + reg = cur_regs(env) + BPF_REG_0; + + if (frame->in_async_callback_fn) { + /* enforce return zero from async callbacks like timer */ + if (reg->type != SCALAR_VALUE) { + verbose(env, "In async callback the register R0 is not a known value (%s)\n", + reg_type_str(env, reg->type)); + return -EINVAL; + } + + if (!tnum_in(const_0, reg->var_off)) { + verbose_invalid_scalar(env, reg, &const_0, "async callback", "R0"); + return -EINVAL; + } + return 0; + } + + if (is_subprog) { + if (reg->type != SCALAR_VALUE) { + verbose(env, "At subprogram exit the register R0 is not a scalar value (%s)\n", + reg_type_str(env, reg->type)); + return -EINVAL; + } + return 0; + } + + switch (prog_type) { + case BPF_PROG_TYPE_CGROUP_SOCK_ADDR: + if (env->prog->expected_attach_type == BPF_CGROUP_UDP4_RECVMSG || + env->prog->expected_attach_type == BPF_CGROUP_UDP6_RECVMSG || + env->prog->expected_attach_type == BPF_CGROUP_INET4_GETPEERNAME || + env->prog->expected_attach_type == BPF_CGROUP_INET6_GETPEERNAME || + env->prog->expected_attach_type == BPF_CGROUP_INET4_GETSOCKNAME || + env->prog->expected_attach_type == BPF_CGROUP_INET6_GETSOCKNAME) + range = tnum_range(1, 1); + if (env->prog->expected_attach_type == BPF_CGROUP_INET4_BIND || + env->prog->expected_attach_type == BPF_CGROUP_INET6_BIND) + range = tnum_range(0, 3); + break; + case BPF_PROG_TYPE_CGROUP_SKB: + if (env->prog->expected_attach_type == BPF_CGROUP_INET_EGRESS) { + range = tnum_range(0, 3); + enforce_attach_type_range = tnum_range(2, 3); + } + break; + case BPF_PROG_TYPE_CGROUP_SOCK: + case BPF_PROG_TYPE_SOCK_OPS: + case BPF_PROG_TYPE_CGROUP_DEVICE: + case BPF_PROG_TYPE_CGROUP_SYSCTL: + case BPF_PROG_TYPE_CGROUP_SOCKOPT: + break; + case BPF_PROG_TYPE_RAW_TRACEPOINT: + if (!env->prog->aux->attach_btf_id) + return 0; + range = tnum_const(0); + break; + case BPF_PROG_TYPE_TRACING: + switch (env->prog->expected_attach_type) { + case BPF_TRACE_FENTRY: + case BPF_TRACE_FEXIT: + range = tnum_const(0); + break; + case BPF_TRACE_RAW_TP: + case BPF_MODIFY_RETURN: + return 0; + case BPF_TRACE_ITER: + break; + default: + return -ENOTSUPP; + } + break; + case BPF_PROG_TYPE_SK_LOOKUP: + range = tnum_range(SK_DROP, SK_PASS); + break; + + case BPF_PROG_TYPE_LSM: + if (env->prog->expected_attach_type != BPF_LSM_CGROUP) { + /* Regular BPF_PROG_TYPE_LSM programs can return + * any value. + */ + return 0; + } + if (!env->prog->aux->attach_func_proto->type) { + /* Make sure programs that attach to void + * hooks don't try to modify return value. + */ + range = tnum_range(1, 1); + } + break; + + case BPF_PROG_TYPE_NETFILTER: + range = tnum_range(NF_DROP, NF_ACCEPT); + break; + case BPF_PROG_TYPE_EXT: + /* freplace program can return anything as its return value + * depends on the to-be-replaced kernel func or bpf program. + */ + default: + return 0; + } + + if (reg->type != SCALAR_VALUE) { + verbose(env, "At program exit the register R0 is not a known value (%s)\n", + reg_type_str(env, reg->type)); + return -EINVAL; + } + + if (!tnum_in(range, reg->var_off)) { + verbose_invalid_scalar(env, reg, &range, "program exit", "R0"); + if (prog->expected_attach_type == BPF_LSM_CGROUP && + prog_type == BPF_PROG_TYPE_LSM && + !prog->aux->attach_func_proto->type) + verbose(env, "Note, BPF_LSM_CGROUP that attach to void LSM hooks can't modify return value!\n"); + return -EINVAL; + } + + if (!tnum_is_unknown(enforce_attach_type_range) && + tnum_in(enforce_attach_type_range, reg->var_off)) + env->prog->enforce_expected_attach_type = 1; + return 0; +} + +/* non-recursive DFS pseudo code + * 1 procedure DFS-iterative(G,v): + * 2 label v as discovered + * 3 let S be a stack + * 4 S.push(v) + * 5 while S is not empty + * 6 t <- S.peek() + * 7 if t is what we're looking for: + * 8 return t + * 9 for all edges e in G.adjacentEdges(t) do + * 10 if edge e is already labelled + * 11 continue with the next edge + * 12 w <- G.adjacentVertex(t,e) + * 13 if vertex w is not discovered and not explored + * 14 label e as tree-edge + * 15 label w as discovered + * 16 S.push(w) + * 17 continue at 5 + * 18 else if vertex w is discovered + * 19 label e as back-edge + * 20 else + * 21 // vertex w is explored + * 22 label e as forward- or cross-edge + * 23 label t as explored + * 24 S.pop() + * + * convention: + * 0x10 - discovered + * 0x11 - discovered and fall-through edge labelled + * 0x12 - discovered and fall-through and branch edges labelled + * 0x20 - explored + */ + +enum { + DISCOVERED = 0x10, + EXPLORED = 0x20, + FALLTHROUGH = 1, + BRANCH = 2, +}; + +static void mark_prune_point(struct bpf_verifier_env *env, int idx) +{ + env->insn_aux_data[idx].prune_point = true; +} + +static bool is_prune_point(struct bpf_verifier_env *env, int insn_idx) +{ + return env->insn_aux_data[insn_idx].prune_point; +} + +static void mark_force_checkpoint(struct bpf_verifier_env *env, int idx) +{ + env->insn_aux_data[idx].force_checkpoint = true; +} + +static bool is_force_checkpoint(struct bpf_verifier_env *env, int insn_idx) +{ + return env->insn_aux_data[insn_idx].force_checkpoint; +} + +static void mark_calls_callback(struct bpf_verifier_env *env, int idx) +{ + env->insn_aux_data[idx].calls_callback = true; +} + +static bool calls_callback(struct bpf_verifier_env *env, int insn_idx) +{ + return env->insn_aux_data[insn_idx].calls_callback; +} + +enum { + DONE_EXPLORING = 0, + KEEP_EXPLORING = 1, +}; + +/* t, w, e - match pseudo-code above: + * t - index of current instruction + * w - next instruction + * e - edge + */ +static int push_insn(int t, int w, int e, struct bpf_verifier_env *env) +{ + int *insn_stack = env->cfg.insn_stack; + int *insn_state = env->cfg.insn_state; + + if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH)) + return DONE_EXPLORING; + + if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH)) + return DONE_EXPLORING; + + if (w < 0 || w >= env->prog->len) { + verbose_linfo(env, t, "%d: ", t); + verbose(env, "jump out of range from insn %d to %d\n", t, w); + return -EINVAL; + } + + if (e == BRANCH) { + /* mark branch target for state pruning */ + mark_prune_point(env, w); + mark_jmp_point(env, w); + } + + if (insn_state[w] == 0) { + /* tree-edge */ + insn_state[t] = DISCOVERED | e; + insn_state[w] = DISCOVERED; + if (env->cfg.cur_stack >= env->prog->len) + return -E2BIG; + insn_stack[env->cfg.cur_stack++] = w; + return KEEP_EXPLORING; + } else if ((insn_state[w] & 0xF0) == DISCOVERED) { + if (env->bpf_capable) + return DONE_EXPLORING; + verbose_linfo(env, t, "%d: ", t); + verbose_linfo(env, w, "%d: ", w); + verbose(env, "back-edge from insn %d to %d\n", t, w); + return -EINVAL; + } else if (insn_state[w] == EXPLORED) { + /* forward- or cross-edge */ + insn_state[t] = DISCOVERED | e; + } else { + verbose(env, "insn state internal bug\n"); + return -EFAULT; + } + return DONE_EXPLORING; +} + +static int visit_func_call_insn(int t, struct bpf_insn *insns, + struct bpf_verifier_env *env, + bool visit_callee) +{ + int ret, insn_sz; + + insn_sz = bpf_is_ldimm64(&insns[t]) ? 2 : 1; + ret = push_insn(t, t + insn_sz, FALLTHROUGH, env); + if (ret) + return ret; + + mark_prune_point(env, t + insn_sz); + /* when we exit from subprog, we need to record non-linear history */ + mark_jmp_point(env, t + insn_sz); + + if (visit_callee) { + mark_prune_point(env, t); + ret = push_insn(t, t + insns[t].imm + 1, BRANCH, env); + } + return ret; +} + +/* Visits the instruction at index t and returns one of the following: + * < 0 - an error occurred + * DONE_EXPLORING - the instruction was fully explored + * KEEP_EXPLORING - there is still work to be done before it is fully explored + */ +static int visit_insn(int t, struct bpf_verifier_env *env) +{ + struct bpf_insn *insns = env->prog->insnsi, *insn = &insns[t]; + int ret, off, insn_sz; + + if (bpf_pseudo_func(insn)) + return visit_func_call_insn(t, insns, env, true); + + /* All non-branch instructions have a single fall-through edge. */ + if (BPF_CLASS(insn->code) != BPF_JMP && + BPF_CLASS(insn->code) != BPF_JMP32) { + insn_sz = bpf_is_ldimm64(insn) ? 2 : 1; + return push_insn(t, t + insn_sz, FALLTHROUGH, env); + } + + switch (BPF_OP(insn->code)) { + case BPF_EXIT: + return DONE_EXPLORING; + + case BPF_CALL: + if (insn->src_reg == 0 && insn->imm == BPF_FUNC_timer_set_callback) + /* Mark this call insn as a prune point to trigger + * is_state_visited() check before call itself is + * processed by __check_func_call(). Otherwise new + * async state will be pushed for further exploration. + */ + mark_prune_point(env, t); + /* For functions that invoke callbacks it is not known how many times + * callback would be called. Verifier models callback calling functions + * by repeatedly visiting callback bodies and returning to origin call + * instruction. + * In order to stop such iteration verifier needs to identify when a + * state identical some state from a previous iteration is reached. + * Check below forces creation of checkpoint before callback calling + * instruction to allow search for such identical states. + */ + if (is_sync_callback_calling_insn(insn)) { + mark_calls_callback(env, t); + mark_force_checkpoint(env, t); + mark_prune_point(env, t); + mark_jmp_point(env, t); + } + if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) { + struct bpf_kfunc_call_arg_meta meta; + + ret = fetch_kfunc_meta(env, insn, &meta, NULL); + if (ret == 0 && is_iter_next_kfunc(&meta)) { + mark_prune_point(env, t); + /* Checking and saving state checkpoints at iter_next() call + * is crucial for fast convergence of open-coded iterator loop + * logic, so we need to force it. If we don't do that, + * is_state_visited() might skip saving a checkpoint, causing + * unnecessarily long sequence of not checkpointed + * instructions and jumps, leading to exhaustion of jump + * history buffer, and potentially other undesired outcomes. + * It is expected that with correct open-coded iterators + * convergence will happen quickly, so we don't run a risk of + * exhausting memory. + */ + mark_force_checkpoint(env, t); + } + } + return visit_func_call_insn(t, insns, env, insn->src_reg == BPF_PSEUDO_CALL); + + case BPF_JA: + if (BPF_SRC(insn->code) != BPF_K) + return -EINVAL; + + if (BPF_CLASS(insn->code) == BPF_JMP) + off = insn->off; + else + off = insn->imm; + + /* unconditional jump with single edge */ + ret = push_insn(t, t + off + 1, FALLTHROUGH, env); + if (ret) + return ret; + + mark_prune_point(env, t + off + 1); + mark_jmp_point(env, t + off + 1); + + return ret; + + default: + /* conditional jump with two edges */ + mark_prune_point(env, t); + + ret = push_insn(t, t + 1, FALLTHROUGH, env); + if (ret) + return ret; + + return push_insn(t, t + insn->off + 1, BRANCH, env); + } +} + +/* non-recursive depth-first-search to detect loops in BPF program + * loop == back-edge in directed graph + */ +static int check_cfg(struct bpf_verifier_env *env) +{ + int insn_cnt = env->prog->len; + int *insn_stack, *insn_state; + int ret = 0; + int i; + + insn_state = env->cfg.insn_state = kvcalloc(insn_cnt, sizeof(int), GFP_KERNEL); + if (!insn_state) + return -ENOMEM; + + insn_stack = env->cfg.insn_stack = kvcalloc(insn_cnt, sizeof(int), GFP_KERNEL); + if (!insn_stack) { + kvfree(insn_state); + return -ENOMEM; + } + + insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */ + insn_stack[0] = 0; /* 0 is the first instruction */ + env->cfg.cur_stack = 1; + + while (env->cfg.cur_stack > 0) { + int t = insn_stack[env->cfg.cur_stack - 1]; + + ret = visit_insn(t, env); + switch (ret) { + case DONE_EXPLORING: + insn_state[t] = EXPLORED; + env->cfg.cur_stack--; + break; + case KEEP_EXPLORING: + break; + default: + if (ret > 0) { + verbose(env, "visit_insn internal bug\n"); + ret = -EFAULT; + } + goto err_free; + } + } + + if (env->cfg.cur_stack < 0) { + verbose(env, "pop stack internal bug\n"); + ret = -EFAULT; + goto err_free; + } + + for (i = 0; i < insn_cnt; i++) { + struct bpf_insn *insn = &env->prog->insnsi[i]; + + if (insn_state[i] != EXPLORED) { + verbose(env, "unreachable insn %d\n", i); + ret = -EINVAL; + goto err_free; + } + if (bpf_is_ldimm64(insn)) { + if (insn_state[i + 1] != 0) { + verbose(env, "jump into the middle of ldimm64 insn %d\n", i); + ret = -EINVAL; + goto err_free; + } + i++; /* skip second half of ldimm64 */ + } + } + ret = 0; /* cfg looks good */ + +err_free: + kvfree(insn_state); + kvfree(insn_stack); + env->cfg.insn_state = env->cfg.insn_stack = NULL; + return ret; +} + +static int check_abnormal_return(struct bpf_verifier_env *env) +{ + int i; + + for (i = 1; i < env->subprog_cnt; i++) { + if (env->subprog_info[i].has_ld_abs) { + verbose(env, "LD_ABS is not allowed in subprogs without BTF\n"); + return -EINVAL; + } + if (env->subprog_info[i].has_tail_call) { + verbose(env, "tail_call is not allowed in subprogs without BTF\n"); + return -EINVAL; + } + } + return 0; +} + +/* The minimum supported BTF func info size */ +#define MIN_BPF_FUNCINFO_SIZE 8 +#define MAX_FUNCINFO_REC_SIZE 252 + +static int check_btf_func(struct bpf_verifier_env *env, + const union bpf_attr *attr, + bpfptr_t uattr) +{ + const struct btf_type *type, *func_proto, *ret_type; + u32 i, nfuncs, urec_size, min_size; + u32 krec_size = sizeof(struct bpf_func_info); + struct bpf_func_info *krecord; + struct bpf_func_info_aux *info_aux = NULL; + struct bpf_prog *prog; + const struct btf *btf; + bpfptr_t urecord; + u32 prev_offset = 0; + bool scalar_return; + int ret = -ENOMEM; + + nfuncs = attr->func_info_cnt; + if (!nfuncs) { + if (check_abnormal_return(env)) + return -EINVAL; + return 0; + } + + if (nfuncs != env->subprog_cnt) { + verbose(env, "number of funcs in func_info doesn't match number of subprogs\n"); + return -EINVAL; + } + + urec_size = attr->func_info_rec_size; + if (urec_size < MIN_BPF_FUNCINFO_SIZE || + urec_size > MAX_FUNCINFO_REC_SIZE || + urec_size % sizeof(u32)) { + verbose(env, "invalid func info rec size %u\n", urec_size); + return -EINVAL; + } + + prog = env->prog; + btf = prog->aux->btf; + + urecord = make_bpfptr(attr->func_info, uattr.is_kernel); + min_size = min_t(u32, krec_size, urec_size); + + krecord = kvcalloc(nfuncs, krec_size, GFP_KERNEL | __GFP_NOWARN); + if (!krecord) + return -ENOMEM; + info_aux = kcalloc(nfuncs, sizeof(*info_aux), GFP_KERNEL | __GFP_NOWARN); + if (!info_aux) + goto err_free; + + for (i = 0; i < nfuncs; i++) { + ret = bpf_check_uarg_tail_zero(urecord, krec_size, urec_size); + if (ret) { + if (ret == -E2BIG) { + verbose(env, "nonzero tailing record in func info"); + /* set the size kernel expects so loader can zero + * out the rest of the record. + */ + if (copy_to_bpfptr_offset(uattr, + offsetof(union bpf_attr, func_info_rec_size), + &min_size, sizeof(min_size))) + ret = -EFAULT; + } + goto err_free; + } + + if (copy_from_bpfptr(&krecord[i], urecord, min_size)) { + ret = -EFAULT; + goto err_free; + } + + /* check insn_off */ + ret = -EINVAL; + if (i == 0) { + if (krecord[i].insn_off) { + verbose(env, + "nonzero insn_off %u for the first func info record", + krecord[i].insn_off); + goto err_free; + } + } else if (krecord[i].insn_off <= prev_offset) { + verbose(env, + "same or smaller insn offset (%u) than previous func info record (%u)", + krecord[i].insn_off, prev_offset); + goto err_free; + } + + if (env->subprog_info[i].start != krecord[i].insn_off) { + verbose(env, "func_info BTF section doesn't match subprog layout in BPF program\n"); + goto err_free; + } + + /* check type_id */ + type = btf_type_by_id(btf, krecord[i].type_id); + if (!type || !btf_type_is_func(type)) { + verbose(env, "invalid type id %d in func info", + krecord[i].type_id); + goto err_free; + } + info_aux[i].linkage = BTF_INFO_VLEN(type->info); + + func_proto = btf_type_by_id(btf, type->type); + if (unlikely(!func_proto || !btf_type_is_func_proto(func_proto))) + /* btf_func_check() already verified it during BTF load */ + goto err_free; + ret_type = btf_type_skip_modifiers(btf, func_proto->type, NULL); + scalar_return = + btf_type_is_small_int(ret_type) || btf_is_any_enum(ret_type); + if (i && !scalar_return && env->subprog_info[i].has_ld_abs) { + verbose(env, "LD_ABS is only allowed in functions that return 'int'.\n"); + goto err_free; + } + if (i && !scalar_return && env->subprog_info[i].has_tail_call) { + verbose(env, "tail_call is only allowed in functions that return 'int'.\n"); + goto err_free; + } + + prev_offset = krecord[i].insn_off; + bpfptr_add(&urecord, urec_size); + } + + prog->aux->func_info = krecord; + prog->aux->func_info_cnt = nfuncs; + prog->aux->func_info_aux = info_aux; + return 0; + +err_free: + kvfree(krecord); + kfree(info_aux); + return ret; +} + +static void adjust_btf_func(struct bpf_verifier_env *env) +{ + struct bpf_prog_aux *aux = env->prog->aux; + int i; + + if (!aux->func_info) + return; + + for (i = 0; i < env->subprog_cnt; i++) + aux->func_info[i].insn_off = env->subprog_info[i].start; +} + +#define MIN_BPF_LINEINFO_SIZE offsetofend(struct bpf_line_info, line_col) +#define MAX_LINEINFO_REC_SIZE MAX_FUNCINFO_REC_SIZE + +static int check_btf_line(struct bpf_verifier_env *env, + const union bpf_attr *attr, + bpfptr_t uattr) +{ + u32 i, s, nr_linfo, ncopy, expected_size, rec_size, prev_offset = 0; + struct bpf_subprog_info *sub; + struct bpf_line_info *linfo; + struct bpf_prog *prog; + const struct btf *btf; + bpfptr_t ulinfo; + int err; + + nr_linfo = attr->line_info_cnt; + if (!nr_linfo) + return 0; + if (nr_linfo > INT_MAX / sizeof(struct bpf_line_info)) + return -EINVAL; + + rec_size = attr->line_info_rec_size; + if (rec_size < MIN_BPF_LINEINFO_SIZE || + rec_size > MAX_LINEINFO_REC_SIZE || + rec_size & (sizeof(u32) - 1)) + return -EINVAL; + + /* Need to zero it in case the userspace may + * pass in a smaller bpf_line_info object. + */ + linfo = kvcalloc(nr_linfo, sizeof(struct bpf_line_info), + GFP_KERNEL | __GFP_NOWARN); + if (!linfo) + return -ENOMEM; + + prog = env->prog; + btf = prog->aux->btf; + + s = 0; + sub = env->subprog_info; + ulinfo = make_bpfptr(attr->line_info, uattr.is_kernel); + expected_size = sizeof(struct bpf_line_info); + ncopy = min_t(u32, expected_size, rec_size); + for (i = 0; i < nr_linfo; i++) { + err = bpf_check_uarg_tail_zero(ulinfo, expected_size, rec_size); + if (err) { + if (err == -E2BIG) { + verbose(env, "nonzero tailing record in line_info"); + if (copy_to_bpfptr_offset(uattr, + offsetof(union bpf_attr, line_info_rec_size), + &expected_size, sizeof(expected_size))) + err = -EFAULT; + } + goto err_free; + } + + if (copy_from_bpfptr(&linfo[i], ulinfo, ncopy)) { + err = -EFAULT; + goto err_free; + } + + /* + * Check insn_off to ensure + * 1) strictly increasing AND + * 2) bounded by prog->len + * + * The linfo[0].insn_off == 0 check logically falls into + * the later "missing bpf_line_info for func..." case + * because the first linfo[0].insn_off must be the + * first sub also and the first sub must have + * subprog_info[0].start == 0. + */ + if ((i && linfo[i].insn_off <= prev_offset) || + linfo[i].insn_off >= prog->len) { + verbose(env, "Invalid line_info[%u].insn_off:%u (prev_offset:%u prog->len:%u)\n", + i, linfo[i].insn_off, prev_offset, + prog->len); + err = -EINVAL; + goto err_free; + } + + if (!prog->insnsi[linfo[i].insn_off].code) { + verbose(env, + "Invalid insn code at line_info[%u].insn_off\n", + i); + err = -EINVAL; + goto err_free; + } + + if (!btf_name_by_offset(btf, linfo[i].line_off) || + !btf_name_by_offset(btf, linfo[i].file_name_off)) { + verbose(env, "Invalid line_info[%u].line_off or .file_name_off\n", i); + err = -EINVAL; + goto err_free; + } + + if (s != env->subprog_cnt) { + if (linfo[i].insn_off == sub[s].start) { + sub[s].linfo_idx = i; + s++; + } else if (sub[s].start < linfo[i].insn_off) { + verbose(env, "missing bpf_line_info for func#%u\n", s); + err = -EINVAL; + goto err_free; + } + } + + prev_offset = linfo[i].insn_off; + bpfptr_add(&ulinfo, rec_size); + } + + if (s != env->subprog_cnt) { + verbose(env, "missing bpf_line_info for %u funcs starting from func#%u\n", + env->subprog_cnt - s, s); + err = -EINVAL; + goto err_free; + } + + prog->aux->linfo = linfo; + prog->aux->nr_linfo = nr_linfo; + + return 0; + +err_free: + kvfree(linfo); + return err; +} + +#define MIN_CORE_RELO_SIZE sizeof(struct bpf_core_relo) +#define MAX_CORE_RELO_SIZE MAX_FUNCINFO_REC_SIZE + +static int check_core_relo(struct bpf_verifier_env *env, + const union bpf_attr *attr, + bpfptr_t uattr) +{ + u32 i, nr_core_relo, ncopy, expected_size, rec_size; + struct bpf_core_relo core_relo = {}; + struct bpf_prog *prog = env->prog; + const struct btf *btf = prog->aux->btf; + struct bpf_core_ctx ctx = { + .log = &env->log, + .btf = btf, + }; + bpfptr_t u_core_relo; + int err; + + nr_core_relo = attr->core_relo_cnt; + if (!nr_core_relo) + return 0; + if (nr_core_relo > INT_MAX / sizeof(struct bpf_core_relo)) + return -EINVAL; + + rec_size = attr->core_relo_rec_size; + if (rec_size < MIN_CORE_RELO_SIZE || + rec_size > MAX_CORE_RELO_SIZE || + rec_size % sizeof(u32)) + return -EINVAL; + + u_core_relo = make_bpfptr(attr->core_relos, uattr.is_kernel); + expected_size = sizeof(struct bpf_core_relo); + ncopy = min_t(u32, expected_size, rec_size); + + /* Unlike func_info and line_info, copy and apply each CO-RE + * relocation record one at a time. + */ + for (i = 0; i < nr_core_relo; i++) { + /* future proofing when sizeof(bpf_core_relo) changes */ + err = bpf_check_uarg_tail_zero(u_core_relo, expected_size, rec_size); + if (err) { + if (err == -E2BIG) { + verbose(env, "nonzero tailing record in core_relo"); + if (copy_to_bpfptr_offset(uattr, + offsetof(union bpf_attr, core_relo_rec_size), + &expected_size, sizeof(expected_size))) + err = -EFAULT; + } + break; + } + + if (copy_from_bpfptr(&core_relo, u_core_relo, ncopy)) { + err = -EFAULT; + break; + } + + if (core_relo.insn_off % 8 || core_relo.insn_off / 8 >= prog->len) { + verbose(env, "Invalid core_relo[%u].insn_off:%u prog->len:%u\n", + i, core_relo.insn_off, prog->len); + err = -EINVAL; + break; + } + + err = bpf_core_apply(&ctx, &core_relo, i, + &prog->insnsi[core_relo.insn_off / 8]); + if (err) + break; + bpfptr_add(&u_core_relo, rec_size); + } + return err; +} + +static int check_btf_info(struct bpf_verifier_env *env, + const union bpf_attr *attr, + bpfptr_t uattr) +{ + struct btf *btf; + int err; + + if (!attr->func_info_cnt && !attr->line_info_cnt) { + if (check_abnormal_return(env)) + return -EINVAL; + return 0; + } + + btf = btf_get_by_fd(attr->prog_btf_fd); + if (IS_ERR(btf)) + return PTR_ERR(btf); + if (btf_is_kernel(btf)) { + btf_put(btf); + return -EACCES; + } + env->prog->aux->btf = btf; + + err = check_btf_func(env, attr, uattr); + if (err) + return err; + + err = check_btf_line(env, attr, uattr); + if (err) + return err; + + err = check_core_relo(env, attr, uattr); + if (err) + return err; + + return 0; +} + +/* check %cur's range satisfies %old's */ +static bool range_within(struct bpf_reg_state *old, + struct bpf_reg_state *cur) +{ + return old->umin_value <= cur->umin_value && + old->umax_value >= cur->umax_value && + old->smin_value <= cur->smin_value && + old->smax_value >= cur->smax_value && + old->u32_min_value <= cur->u32_min_value && + old->u32_max_value >= cur->u32_max_value && + old->s32_min_value <= cur->s32_min_value && + old->s32_max_value >= cur->s32_max_value; +} + +/* If in the old state two registers had the same id, then they need to have + * the same id in the new state as well. But that id could be different from + * the old state, so we need to track the mapping from old to new ids. + * Once we have seen that, say, a reg with old id 5 had new id 9, any subsequent + * regs with old id 5 must also have new id 9 for the new state to be safe. But + * regs with a different old id could still have new id 9, we don't care about + * that. + * So we look through our idmap to see if this old id has been seen before. If + * so, we require the new id to match; otherwise, we add the id pair to the map. + */ +static bool check_ids(u32 old_id, u32 cur_id, struct bpf_idmap *idmap) +{ + struct bpf_id_pair *map = idmap->map; + unsigned int i; + + /* either both IDs should be set or both should be zero */ + if (!!old_id != !!cur_id) + return false; + + if (old_id == 0) /* cur_id == 0 as well */ + return true; + + for (i = 0; i < BPF_ID_MAP_SIZE; i++) { + if (!map[i].old) { + /* Reached an empty slot; haven't seen this id before */ + map[i].old = old_id; + map[i].cur = cur_id; + return true; + } + if (map[i].old == old_id) + return map[i].cur == cur_id; + if (map[i].cur == cur_id) + return false; + } + /* We ran out of idmap slots, which should be impossible */ + WARN_ON_ONCE(1); + return false; +} + +/* Similar to check_ids(), but allocate a unique temporary ID + * for 'old_id' or 'cur_id' of zero. + * This makes pairs like '0 vs unique ID', 'unique ID vs 0' valid. + */ +static bool check_scalar_ids(u32 old_id, u32 cur_id, struct bpf_idmap *idmap) +{ + old_id = old_id ? old_id : ++idmap->tmp_id_gen; + cur_id = cur_id ? cur_id : ++idmap->tmp_id_gen; + + return check_ids(old_id, cur_id, idmap); +} + +static void clean_func_state(struct bpf_verifier_env *env, + struct bpf_func_state *st) +{ + enum bpf_reg_liveness live; + int i, j; + + for (i = 0; i < BPF_REG_FP; i++) { + live = st->regs[i].live; + /* liveness must not touch this register anymore */ + st->regs[i].live |= REG_LIVE_DONE; + if (!(live & REG_LIVE_READ)) + /* since the register is unused, clear its state + * to make further comparison simpler + */ + __mark_reg_not_init(env, &st->regs[i]); + } + + for (i = 0; i < st->allocated_stack / BPF_REG_SIZE; i++) { + live = st->stack[i].spilled_ptr.live; + /* liveness must not touch this stack slot anymore */ + st->stack[i].spilled_ptr.live |= REG_LIVE_DONE; + if (!(live & REG_LIVE_READ)) { + __mark_reg_not_init(env, &st->stack[i].spilled_ptr); + for (j = 0; j < BPF_REG_SIZE; j++) + st->stack[i].slot_type[j] = STACK_INVALID; + } + } +} + +static void clean_verifier_state(struct bpf_verifier_env *env, + struct bpf_verifier_state *st) +{ + int i; + + if (st->frame[0]->regs[0].live & REG_LIVE_DONE) + /* all regs in this state in all frames were already marked */ + return; + + for (i = 0; i <= st->curframe; i++) + clean_func_state(env, st->frame[i]); +} + +/* the parentage chains form a tree. + * the verifier states are added to state lists at given insn and + * pushed into state stack for future exploration. + * when the verifier reaches bpf_exit insn some of the verifer states + * stored in the state lists have their final liveness state already, + * but a lot of states will get revised from liveness point of view when + * the verifier explores other branches. + * Example: + * 1: r0 = 1 + * 2: if r1 == 100 goto pc+1 + * 3: r0 = 2 + * 4: exit + * when the verifier reaches exit insn the register r0 in the state list of + * insn 2 will be seen as !REG_LIVE_READ. Then the verifier pops the other_branch + * of insn 2 and goes exploring further. At the insn 4 it will walk the + * parentage chain from insn 4 into insn 2 and will mark r0 as REG_LIVE_READ. + * + * Since the verifier pushes the branch states as it sees them while exploring + * the program the condition of walking the branch instruction for the second + * time means that all states below this branch were already explored and + * their final liveness marks are already propagated. + * Hence when the verifier completes the search of state list in is_state_visited() + * we can call this clean_live_states() function to mark all liveness states + * as REG_LIVE_DONE to indicate that 'parent' pointers of 'struct bpf_reg_state' + * will not be used. + * This function also clears the registers and stack for states that !READ + * to simplify state merging. + * + * Important note here that walking the same branch instruction in the callee + * doesn't meant that the states are DONE. The verifier has to compare + * the callsites + */ +static void clean_live_states(struct bpf_verifier_env *env, int insn, + struct bpf_verifier_state *cur) +{ + struct bpf_verifier_state_list *sl; + + sl = *explored_state(env, insn); + while (sl) { + if (sl->state.branches) + goto next; + if (sl->state.insn_idx != insn || + !same_callsites(&sl->state, cur)) + goto next; + clean_verifier_state(env, &sl->state); +next: + sl = sl->next; + } +} + +static bool regs_exact(const struct bpf_reg_state *rold, + const struct bpf_reg_state *rcur, + struct bpf_idmap *idmap) +{ + return memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)) == 0 && + check_ids(rold->id, rcur->id, idmap) && + check_ids(rold->ref_obj_id, rcur->ref_obj_id, idmap); +} + +/* Returns true if (rold safe implies rcur safe) */ +static bool regsafe(struct bpf_verifier_env *env, struct bpf_reg_state *rold, + struct bpf_reg_state *rcur, struct bpf_idmap *idmap, bool exact) +{ + if (exact) + return regs_exact(rold, rcur, idmap); + + if (!(rold->live & REG_LIVE_READ)) + /* explored state didn't use this */ + return true; + if (rold->type == NOT_INIT) + /* explored state can't have used this */ + return true; + if (rcur->type == NOT_INIT) + return false; + + /* Enforce that register types have to match exactly, including their + * modifiers (like PTR_MAYBE_NULL, MEM_RDONLY, etc), as a general + * rule. + * + * One can make a point that using a pointer register as unbounded + * SCALAR would be technically acceptable, but this could lead to + * pointer leaks because scalars are allowed to leak while pointers + * are not. We could make this safe in special cases if root is + * calling us, but it's probably not worth the hassle. + * + * Also, register types that are *not* MAYBE_NULL could technically be + * safe to use as their MAYBE_NULL variants (e.g., PTR_TO_MAP_VALUE + * is safe to be used as PTR_TO_MAP_VALUE_OR_NULL, provided both point + * to the same map). + * However, if the old MAYBE_NULL register then got NULL checked, + * doing so could have affected others with the same id, and we can't + * check for that because we lost the id when we converted to + * a non-MAYBE_NULL variant. + * So, as a general rule we don't allow mixing MAYBE_NULL and + * non-MAYBE_NULL registers as well. + */ + if (rold->type != rcur->type) + return false; + + switch (base_type(rold->type)) { + case SCALAR_VALUE: + if (env->explore_alu_limits) { + /* explore_alu_limits disables tnum_in() and range_within() + * logic and requires everything to be strict + */ + return memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)) == 0 && + check_scalar_ids(rold->id, rcur->id, idmap); + } + if (!rold->precise) + return true; + /* Why check_ids() for scalar registers? + * + * Consider the following BPF code: + * 1: r6 = ... unbound scalar, ID=a ... + * 2: r7 = ... unbound scalar, ID=b ... + * 3: if (r6 > r7) goto +1 + * 4: r6 = r7 + * 5: if (r6 > X) goto ... + * 6: ... memory operation using r7 ... + * + * First verification path is [1-6]: + * - at (4) same bpf_reg_state::id (b) would be assigned to r6 and r7; + * - at (5) r6 would be marked <= X, find_equal_scalars() would also mark + * r7 <= X, because r6 and r7 share same id. + * Next verification path is [1-4, 6]. + * + * Instruction (6) would be reached in two states: + * I. r6{.id=b}, r7{.id=b} via path 1-6; + * II. r6{.id=a}, r7{.id=b} via path 1-4, 6. + * + * Use check_ids() to distinguish these states. + * --- + * Also verify that new value satisfies old value range knowledge. + */ + return range_within(rold, rcur) && + tnum_in(rold->var_off, rcur->var_off) && + check_scalar_ids(rold->id, rcur->id, idmap); + case PTR_TO_MAP_KEY: + case PTR_TO_MAP_VALUE: + case PTR_TO_MEM: + case PTR_TO_BUF: + case PTR_TO_TP_BUFFER: + /* If the new min/max/var_off satisfy the old ones and + * everything else matches, we are OK. + */ + return memcmp(rold, rcur, offsetof(struct bpf_reg_state, var_off)) == 0 && + range_within(rold, rcur) && + tnum_in(rold->var_off, rcur->var_off) && + check_ids(rold->id, rcur->id, idmap) && + check_ids(rold->ref_obj_id, rcur->ref_obj_id, idmap); + case PTR_TO_PACKET_META: + case PTR_TO_PACKET: + /* We must have at least as much range as the old ptr + * did, so that any accesses which were safe before are + * still safe. This is true even if old range < old off, + * since someone could have accessed through (ptr - k), or + * even done ptr -= k in a register, to get a safe access. + */ + if (rold->range > rcur->range) + return false; + /* If the offsets don't match, we can't trust our alignment; + * nor can we be sure that we won't fall out of range. + */ + if (rold->off != rcur->off) + return false; + /* id relations must be preserved */ + if (!check_ids(rold->id, rcur->id, idmap)) + return false; + /* new val must satisfy old val knowledge */ + return range_within(rold, rcur) && + tnum_in(rold->var_off, rcur->var_off); + case PTR_TO_STACK: + /* two stack pointers are equal only if they're pointing to + * the same stack frame, since fp-8 in foo != fp-8 in bar + */ + return regs_exact(rold, rcur, idmap) && rold->frameno == rcur->frameno; + default: + return regs_exact(rold, rcur, idmap); + } +} + +static bool stacksafe(struct bpf_verifier_env *env, struct bpf_func_state *old, + struct bpf_func_state *cur, struct bpf_idmap *idmap, bool exact) +{ + int i, spi; + + /* walk slots of the explored stack and ignore any additional + * slots in the current stack, since explored(safe) state + * didn't use them + */ + for (i = 0; i < old->allocated_stack; i++) { + struct bpf_reg_state *old_reg, *cur_reg; + + spi = i / BPF_REG_SIZE; + + if (exact && + old->stack[spi].slot_type[i % BPF_REG_SIZE] != + cur->stack[spi].slot_type[i % BPF_REG_SIZE]) + return false; + + if (!(old->stack[spi].spilled_ptr.live & REG_LIVE_READ) && !exact) { + i += BPF_REG_SIZE - 1; + /* explored state didn't use this */ + continue; + } + + if (old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_INVALID) + continue; + + if (env->allow_uninit_stack && + old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_MISC) + continue; + + /* explored stack has more populated slots than current stack + * and these slots were used + */ + if (i >= cur->allocated_stack) + return false; + + /* if old state was safe with misc data in the stack + * it will be safe with zero-initialized stack. + * The opposite is not true + */ + if (old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_MISC && + cur->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_ZERO) + continue; + if (old->stack[spi].slot_type[i % BPF_REG_SIZE] != + cur->stack[spi].slot_type[i % BPF_REG_SIZE]) + /* Ex: old explored (safe) state has STACK_SPILL in + * this stack slot, but current has STACK_MISC -> + * this verifier states are not equivalent, + * return false to continue verification of this path + */ + return false; + if (i % BPF_REG_SIZE != BPF_REG_SIZE - 1) + continue; + /* Both old and cur are having same slot_type */ + switch (old->stack[spi].slot_type[BPF_REG_SIZE - 1]) { + case STACK_SPILL: + /* when explored and current stack slot are both storing + * spilled registers, check that stored pointers types + * are the same as well. + * Ex: explored safe path could have stored + * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -8} + * but current path has stored: + * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -16} + * such verifier states are not equivalent. + * return false to continue verification of this path + */ + if (!regsafe(env, &old->stack[spi].spilled_ptr, + &cur->stack[spi].spilled_ptr, idmap, exact)) + return false; + break; + case STACK_DYNPTR: + old_reg = &old->stack[spi].spilled_ptr; + cur_reg = &cur->stack[spi].spilled_ptr; + if (old_reg->dynptr.type != cur_reg->dynptr.type || + old_reg->dynptr.first_slot != cur_reg->dynptr.first_slot || + !check_ids(old_reg->ref_obj_id, cur_reg->ref_obj_id, idmap)) + return false; + break; + case STACK_ITER: + old_reg = &old->stack[spi].spilled_ptr; + cur_reg = &cur->stack[spi].spilled_ptr; + /* iter.depth is not compared between states as it + * doesn't matter for correctness and would otherwise + * prevent convergence; we maintain it only to prevent + * infinite loop check triggering, see + * iter_active_depths_differ() + */ + if (old_reg->iter.btf != cur_reg->iter.btf || + old_reg->iter.btf_id != cur_reg->iter.btf_id || + old_reg->iter.state != cur_reg->iter.state || + /* ignore {old_reg,cur_reg}->iter.depth, see above */ + !check_ids(old_reg->ref_obj_id, cur_reg->ref_obj_id, idmap)) + return false; + break; + case STACK_MISC: + case STACK_ZERO: + case STACK_INVALID: + continue; + /* Ensure that new unhandled slot types return false by default */ + default: + return false; + } + } + return true; +} + +static bool refsafe(struct bpf_func_state *old, struct bpf_func_state *cur, + struct bpf_idmap *idmap) +{ + int i; + + if (old->acquired_refs != cur->acquired_refs) + return false; + + for (i = 0; i < old->acquired_refs; i++) { + if (!check_ids(old->refs[i].id, cur->refs[i].id, idmap)) + return false; + } + + return true; +} + +/* compare two verifier states + * + * all states stored in state_list are known to be valid, since + * verifier reached 'bpf_exit' instruction through them + * + * this function is called when verifier exploring different branches of + * execution popped from the state stack. If it sees an old state that has + * more strict register state and more strict stack state then this execution + * branch doesn't need to be explored further, since verifier already + * concluded that more strict state leads to valid finish. + * + * Therefore two states are equivalent if register state is more conservative + * and explored stack state is more conservative than the current one. + * Example: + * explored current + * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC) + * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC) + * + * In other words if current stack state (one being explored) has more + * valid slots than old one that already passed validation, it means + * the verifier can stop exploring and conclude that current state is valid too + * + * Similarly with registers. If explored state has register type as invalid + * whereas register type in current state is meaningful, it means that + * the current state will reach 'bpf_exit' instruction safely + */ +static bool func_states_equal(struct bpf_verifier_env *env, struct bpf_func_state *old, + struct bpf_func_state *cur, bool exact) +{ + int i; + + for (i = 0; i < MAX_BPF_REG; i++) + if (!regsafe(env, &old->regs[i], &cur->regs[i], + &env->idmap_scratch, exact)) + return false; + + if (!stacksafe(env, old, cur, &env->idmap_scratch, exact)) + return false; + + if (!refsafe(old, cur, &env->idmap_scratch)) + return false; + + return true; +} + +static void reset_idmap_scratch(struct bpf_verifier_env *env) +{ + env->idmap_scratch.tmp_id_gen = env->id_gen; + memset(&env->idmap_scratch.map, 0, sizeof(env->idmap_scratch.map)); +} + +static bool states_equal(struct bpf_verifier_env *env, + struct bpf_verifier_state *old, + struct bpf_verifier_state *cur, + bool exact) +{ + int i; + + if (old->curframe != cur->curframe) + return false; + + reset_idmap_scratch(env); + + /* Verification state from speculative execution simulation + * must never prune a non-speculative execution one. + */ + if (old->speculative && !cur->speculative) + return false; + + if (old->active_lock.ptr != cur->active_lock.ptr) + return false; + + /* Old and cur active_lock's have to be either both present + * or both absent. + */ + if (!!old->active_lock.id != !!cur->active_lock.id) + return false; + + if (old->active_lock.id && + !check_ids(old->active_lock.id, cur->active_lock.id, &env->idmap_scratch)) + return false; + + if (old->active_rcu_lock != cur->active_rcu_lock) + return false; + + /* for states to be equal callsites have to be the same + * and all frame states need to be equivalent + */ + for (i = 0; i <= old->curframe; i++) { + if (old->frame[i]->callsite != cur->frame[i]->callsite) + return false; + if (!func_states_equal(env, old->frame[i], cur->frame[i], exact)) + return false; + } + return true; +} + +/* Return 0 if no propagation happened. Return negative error code if error + * happened. Otherwise, return the propagated bit. + */ +static int propagate_liveness_reg(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, + struct bpf_reg_state *parent_reg) +{ + u8 parent_flag = parent_reg->live & REG_LIVE_READ; + u8 flag = reg->live & REG_LIVE_READ; + int err; + + /* When comes here, read flags of PARENT_REG or REG could be any of + * REG_LIVE_READ64, REG_LIVE_READ32, REG_LIVE_NONE. There is no need + * of propagation if PARENT_REG has strongest REG_LIVE_READ64. + */ + if (parent_flag == REG_LIVE_READ64 || + /* Or if there is no read flag from REG. */ + !flag || + /* Or if the read flag from REG is the same as PARENT_REG. */ + parent_flag == flag) + return 0; + + err = mark_reg_read(env, reg, parent_reg, flag); + if (err) + return err; + + return flag; +} + +/* A write screens off any subsequent reads; but write marks come from the + * straight-line code between a state and its parent. When we arrive at an + * equivalent state (jump target or such) we didn't arrive by the straight-line + * code, so read marks in the state must propagate to the parent regardless + * of the state's write marks. That's what 'parent == state->parent' comparison + * in mark_reg_read() is for. + */ +static int propagate_liveness(struct bpf_verifier_env *env, + const struct bpf_verifier_state *vstate, + struct bpf_verifier_state *vparent) +{ + struct bpf_reg_state *state_reg, *parent_reg; + struct bpf_func_state *state, *parent; + int i, frame, err = 0; + + if (vparent->curframe != vstate->curframe) { + WARN(1, "propagate_live: parent frame %d current frame %d\n", + vparent->curframe, vstate->curframe); + return -EFAULT; + } + /* Propagate read liveness of registers... */ + BUILD_BUG_ON(BPF_REG_FP + 1 != MAX_BPF_REG); + for (frame = 0; frame <= vstate->curframe; frame++) { + parent = vparent->frame[frame]; + state = vstate->frame[frame]; + parent_reg = parent->regs; + state_reg = state->regs; + /* We don't need to worry about FP liveness, it's read-only */ + for (i = frame < vstate->curframe ? BPF_REG_6 : 0; i < BPF_REG_FP; i++) { + err = propagate_liveness_reg(env, &state_reg[i], + &parent_reg[i]); + if (err < 0) + return err; + if (err == REG_LIVE_READ64) + mark_insn_zext(env, &parent_reg[i]); + } + + /* Propagate stack slots. */ + for (i = 0; i < state->allocated_stack / BPF_REG_SIZE && + i < parent->allocated_stack / BPF_REG_SIZE; i++) { + parent_reg = &parent->stack[i].spilled_ptr; + state_reg = &state->stack[i].spilled_ptr; + err = propagate_liveness_reg(env, state_reg, + parent_reg); + if (err < 0) + return err; + } + } + return 0; +} + +/* find precise scalars in the previous equivalent state and + * propagate them into the current state + */ +static int propagate_precision(struct bpf_verifier_env *env, + const struct bpf_verifier_state *old) +{ + struct bpf_reg_state *state_reg; + struct bpf_func_state *state; + int i, err = 0, fr; + bool first; + + for (fr = old->curframe; fr >= 0; fr--) { + state = old->frame[fr]; + state_reg = state->regs; + first = true; + for (i = 0; i < BPF_REG_FP; i++, state_reg++) { + if (state_reg->type != SCALAR_VALUE || + !state_reg->precise || + !(state_reg->live & REG_LIVE_READ)) + continue; + if (env->log.level & BPF_LOG_LEVEL2) { + if (first) + verbose(env, "frame %d: propagating r%d", fr, i); + else + verbose(env, ",r%d", i); + } + bt_set_frame_reg(&env->bt, fr, i); + first = false; + } + + for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) { + if (!is_spilled_reg(&state->stack[i])) + continue; + state_reg = &state->stack[i].spilled_ptr; + if (state_reg->type != SCALAR_VALUE || + !state_reg->precise || + !(state_reg->live & REG_LIVE_READ)) + continue; + if (env->log.level & BPF_LOG_LEVEL2) { + if (first) + verbose(env, "frame %d: propagating fp%d", + fr, (-i - 1) * BPF_REG_SIZE); + else + verbose(env, ",fp%d", (-i - 1) * BPF_REG_SIZE); + } + bt_set_frame_slot(&env->bt, fr, i); + first = false; + } + if (!first) + verbose(env, "\n"); + } + + err = mark_chain_precision_batch(env); + if (err < 0) + return err; + + return 0; +} + +static bool states_maybe_looping(struct bpf_verifier_state *old, + struct bpf_verifier_state *cur) +{ + struct bpf_func_state *fold, *fcur; + int i, fr = cur->curframe; + + if (old->curframe != fr) + return false; + + fold = old->frame[fr]; + fcur = cur->frame[fr]; + for (i = 0; i < MAX_BPF_REG; i++) + if (memcmp(&fold->regs[i], &fcur->regs[i], + offsetof(struct bpf_reg_state, parent))) + return false; + return true; +} + +static bool is_iter_next_insn(struct bpf_verifier_env *env, int insn_idx) +{ + return env->insn_aux_data[insn_idx].is_iter_next; +} + +/* is_state_visited() handles iter_next() (see process_iter_next_call() for + * terminology) calls specially: as opposed to bounded BPF loops, it *expects* + * states to match, which otherwise would look like an infinite loop. So while + * iter_next() calls are taken care of, we still need to be careful and + * prevent erroneous and too eager declaration of "ininite loop", when + * iterators are involved. + * + * Here's a situation in pseudo-BPF assembly form: + * + * 0: again: ; set up iter_next() call args + * 1: r1 = &it ; <CHECKPOINT HERE> + * 2: call bpf_iter_num_next ; this is iter_next() call + * 3: if r0 == 0 goto done + * 4: ... something useful here ... + * 5: goto again ; another iteration + * 6: done: + * 7: r1 = &it + * 8: call bpf_iter_num_destroy ; clean up iter state + * 9: exit + * + * This is a typical loop. Let's assume that we have a prune point at 1:, + * before we get to `call bpf_iter_num_next` (e.g., because of that `goto + * again`, assuming other heuristics don't get in a way). + * + * When we first time come to 1:, let's say we have some state X. We proceed + * to 2:, fork states, enqueue ACTIVE, validate NULL case successfully, exit. + * Now we come back to validate that forked ACTIVE state. We proceed through + * 3-5, come to goto, jump to 1:. Let's assume our state didn't change, so we + * are converging. But the problem is that we don't know that yet, as this + * convergence has to happen at iter_next() call site only. So if nothing is + * done, at 1: verifier will use bounded loop logic and declare infinite + * looping (and would be *technically* correct, if not for iterator's + * "eventual sticky NULL" contract, see process_iter_next_call()). But we + * don't want that. So what we do in process_iter_next_call() when we go on + * another ACTIVE iteration, we bump slot->iter.depth, to mark that it's + * a different iteration. So when we suspect an infinite loop, we additionally + * check if any of the *ACTIVE* iterator states depths differ. If yes, we + * pretend we are not looping and wait for next iter_next() call. + * + * This only applies to ACTIVE state. In DRAINED state we don't expect to + * loop, because that would actually mean infinite loop, as DRAINED state is + * "sticky", and so we'll keep returning into the same instruction with the + * same state (at least in one of possible code paths). + * + * This approach allows to keep infinite loop heuristic even in the face of + * active iterator. E.g., C snippet below is and will be detected as + * inifintely looping: + * + * struct bpf_iter_num it; + * int *p, x; + * + * bpf_iter_num_new(&it, 0, 10); + * while ((p = bpf_iter_num_next(&t))) { + * x = p; + * while (x--) {} // <<-- infinite loop here + * } + * + */ +static bool iter_active_depths_differ(struct bpf_verifier_state *old, struct bpf_verifier_state *cur) +{ + struct bpf_reg_state *slot, *cur_slot; + struct bpf_func_state *state; + int i, fr; + + for (fr = old->curframe; fr >= 0; fr--) { + state = old->frame[fr]; + for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) { + if (state->stack[i].slot_type[0] != STACK_ITER) + continue; + + slot = &state->stack[i].spilled_ptr; + if (slot->iter.state != BPF_ITER_STATE_ACTIVE) + continue; + + cur_slot = &cur->frame[fr]->stack[i].spilled_ptr; + if (cur_slot->iter.depth != slot->iter.depth) + return true; + } + } + return false; +} + +static int is_state_visited(struct bpf_verifier_env *env, int insn_idx) +{ + struct bpf_verifier_state_list *new_sl; + struct bpf_verifier_state_list *sl, **pprev; + struct bpf_verifier_state *cur = env->cur_state, *new, *loop_entry; + int i, j, n, err, states_cnt = 0; + bool force_new_state = env->test_state_freq || is_force_checkpoint(env, insn_idx); + bool add_new_state = force_new_state; + bool force_exact; + + /* bpf progs typically have pruning point every 4 instructions + * http://vger.kernel.org/bpfconf2019.html#session-1 + * Do not add new state for future pruning if the verifier hasn't seen + * at least 2 jumps and at least 8 instructions. + * This heuristics helps decrease 'total_states' and 'peak_states' metric. + * In tests that amounts to up to 50% reduction into total verifier + * memory consumption and 20% verifier time speedup. + */ + if (env->jmps_processed - env->prev_jmps_processed >= 2 && + env->insn_processed - env->prev_insn_processed >= 8) + add_new_state = true; + + pprev = explored_state(env, insn_idx); + sl = *pprev; + + clean_live_states(env, insn_idx, cur); + + while (sl) { + states_cnt++; + if (sl->state.insn_idx != insn_idx) + goto next; + + if (sl->state.branches) { + struct bpf_func_state *frame = sl->state.frame[sl->state.curframe]; + + if (frame->in_async_callback_fn && + frame->async_entry_cnt != cur->frame[cur->curframe]->async_entry_cnt) { + /* Different async_entry_cnt means that the verifier is + * processing another entry into async callback. + * Seeing the same state is not an indication of infinite + * loop or infinite recursion. + * But finding the same state doesn't mean that it's safe + * to stop processing the current state. The previous state + * hasn't yet reached bpf_exit, since state.branches > 0. + * Checking in_async_callback_fn alone is not enough either. + * Since the verifier still needs to catch infinite loops + * inside async callbacks. + */ + goto skip_inf_loop_check; + } + /* BPF open-coded iterators loop detection is special. + * states_maybe_looping() logic is too simplistic in detecting + * states that *might* be equivalent, because it doesn't know + * about ID remapping, so don't even perform it. + * See process_iter_next_call() and iter_active_depths_differ() + * for overview of the logic. When current and one of parent + * states are detected as equivalent, it's a good thing: we prove + * convergence and can stop simulating further iterations. + * It's safe to assume that iterator loop will finish, taking into + * account iter_next() contract of eventually returning + * sticky NULL result. + * + * Note, that states have to be compared exactly in this case because + * read and precision marks might not be finalized inside the loop. + * E.g. as in the program below: + * + * 1. r7 = -16 + * 2. r6 = bpf_get_prandom_u32() + * 3. while (bpf_iter_num_next(&fp[-8])) { + * 4. if (r6 != 42) { + * 5. r7 = -32 + * 6. r6 = bpf_get_prandom_u32() + * 7. continue + * 8. } + * 9. r0 = r10 + * 10. r0 += r7 + * 11. r8 = *(u64 *)(r0 + 0) + * 12. r6 = bpf_get_prandom_u32() + * 13. } + * + * Here verifier would first visit path 1-3, create a checkpoint at 3 + * with r7=-16, continue to 4-7,3. Existing checkpoint at 3 does + * not have read or precision mark for r7 yet, thus inexact states + * comparison would discard current state with r7=-32 + * => unsafe memory access at 11 would not be caught. + */ + if (is_iter_next_insn(env, insn_idx)) { + if (states_equal(env, &sl->state, cur, true)) { + struct bpf_func_state *cur_frame; + struct bpf_reg_state *iter_state, *iter_reg; + int spi; + + cur_frame = cur->frame[cur->curframe]; + /* btf_check_iter_kfuncs() enforces that + * iter state pointer is always the first arg + */ + iter_reg = &cur_frame->regs[BPF_REG_1]; + /* current state is valid due to states_equal(), + * so we can assume valid iter and reg state, + * no need for extra (re-)validations + */ + spi = __get_spi(iter_reg->off + iter_reg->var_off.value); + iter_state = &func(env, iter_reg)->stack[spi].spilled_ptr; + if (iter_state->iter.state == BPF_ITER_STATE_ACTIVE) { + update_loop_entry(cur, &sl->state); + goto hit; + } + } + goto skip_inf_loop_check; + } + if (calls_callback(env, insn_idx)) { + if (states_equal(env, &sl->state, cur, true)) + goto hit; + goto skip_inf_loop_check; + } + /* attempt to detect infinite loop to avoid unnecessary doomed work */ + if (states_maybe_looping(&sl->state, cur) && + states_equal(env, &sl->state, cur, false) && + !iter_active_depths_differ(&sl->state, cur) && + sl->state.callback_unroll_depth == cur->callback_unroll_depth) { + verbose_linfo(env, insn_idx, "; "); + verbose(env, "infinite loop detected at insn %d\n", insn_idx); + verbose(env, "cur state:"); + print_verifier_state(env, cur->frame[cur->curframe], true); + verbose(env, "old state:"); + print_verifier_state(env, sl->state.frame[cur->curframe], true); + return -EINVAL; + } + /* if the verifier is processing a loop, avoid adding new state + * too often, since different loop iterations have distinct + * states and may not help future pruning. + * This threshold shouldn't be too low to make sure that + * a loop with large bound will be rejected quickly. + * The most abusive loop will be: + * r1 += 1 + * if r1 < 1000000 goto pc-2 + * 1M insn_procssed limit / 100 == 10k peak states. + * This threshold shouldn't be too high either, since states + * at the end of the loop are likely to be useful in pruning. + */ +skip_inf_loop_check: + if (!force_new_state && + env->jmps_processed - env->prev_jmps_processed < 20 && + env->insn_processed - env->prev_insn_processed < 100) + add_new_state = false; + goto miss; + } + /* If sl->state is a part of a loop and this loop's entry is a part of + * current verification path then states have to be compared exactly. + * 'force_exact' is needed to catch the following case: + * + * initial Here state 'succ' was processed first, + * | it was eventually tracked to produce a + * V state identical to 'hdr'. + * .---------> hdr All branches from 'succ' had been explored + * | | and thus 'succ' has its .branches == 0. + * | V + * | .------... Suppose states 'cur' and 'succ' correspond + * | | | to the same instruction + callsites. + * | V V In such case it is necessary to check + * | ... ... if 'succ' and 'cur' are states_equal(). + * | | | If 'succ' and 'cur' are a part of the + * | V V same loop exact flag has to be set. + * | succ <- cur To check if that is the case, verify + * | | if loop entry of 'succ' is in current + * | V DFS path. + * | ... + * | | + * '----' + * + * Additional details are in the comment before get_loop_entry(). + */ + loop_entry = get_loop_entry(&sl->state); + force_exact = loop_entry && loop_entry->branches > 0; + if (states_equal(env, &sl->state, cur, force_exact)) { + if (force_exact) + update_loop_entry(cur, loop_entry); +hit: + sl->hit_cnt++; + /* reached equivalent register/stack state, + * prune the search. + * Registers read by the continuation are read by us. + * If we have any write marks in env->cur_state, they + * will prevent corresponding reads in the continuation + * from reaching our parent (an explored_state). Our + * own state will get the read marks recorded, but + * they'll be immediately forgotten as we're pruning + * this state and will pop a new one. + */ + err = propagate_liveness(env, &sl->state, cur); + + /* if previous state reached the exit with precision and + * current state is equivalent to it (except precsion marks) + * the precision needs to be propagated back in + * the current state. + */ + err = err ? : push_jmp_history(env, cur); + err = err ? : propagate_precision(env, &sl->state); + if (err) + return err; + return 1; + } +miss: + /* when new state is not going to be added do not increase miss count. + * Otherwise several loop iterations will remove the state + * recorded earlier. The goal of these heuristics is to have + * states from some iterations of the loop (some in the beginning + * and some at the end) to help pruning. + */ + if (add_new_state) + sl->miss_cnt++; + /* heuristic to determine whether this state is beneficial + * to keep checking from state equivalence point of view. + * Higher numbers increase max_states_per_insn and verification time, + * but do not meaningfully decrease insn_processed. + * 'n' controls how many times state could miss before eviction. + * Use bigger 'n' for checkpoints because evicting checkpoint states + * too early would hinder iterator convergence. + */ + n = is_force_checkpoint(env, insn_idx) && sl->state.branches > 0 ? 64 : 3; + if (sl->miss_cnt > sl->hit_cnt * n + n) { + /* the state is unlikely to be useful. Remove it to + * speed up verification + */ + *pprev = sl->next; + if (sl->state.frame[0]->regs[0].live & REG_LIVE_DONE && + !sl->state.used_as_loop_entry) { + u32 br = sl->state.branches; + + WARN_ONCE(br, + "BUG live_done but branches_to_explore %d\n", + br); + free_verifier_state(&sl->state, false); + kfree(sl); + env->peak_states--; + } else { + /* cannot free this state, since parentage chain may + * walk it later. Add it for free_list instead to + * be freed at the end of verification + */ + sl->next = env->free_list; + env->free_list = sl; + } + sl = *pprev; + continue; + } +next: + pprev = &sl->next; + sl = *pprev; + } + + if (env->max_states_per_insn < states_cnt) + env->max_states_per_insn = states_cnt; + + if (!env->bpf_capable && states_cnt > BPF_COMPLEXITY_LIMIT_STATES) + return 0; + + if (!add_new_state) + return 0; + + /* There were no equivalent states, remember the current one. + * Technically the current state is not proven to be safe yet, + * but it will either reach outer most bpf_exit (which means it's safe) + * or it will be rejected. When there are no loops the verifier won't be + * seeing this tuple (frame[0].callsite, frame[1].callsite, .. insn_idx) + * again on the way to bpf_exit. + * When looping the sl->state.branches will be > 0 and this state + * will not be considered for equivalence until branches == 0. + */ + new_sl = kzalloc(sizeof(struct bpf_verifier_state_list), GFP_KERNEL); + if (!new_sl) + return -ENOMEM; + env->total_states++; + env->peak_states++; + env->prev_jmps_processed = env->jmps_processed; + env->prev_insn_processed = env->insn_processed; + + /* forget precise markings we inherited, see __mark_chain_precision */ + if (env->bpf_capable) + mark_all_scalars_imprecise(env, cur); + + /* add new state to the head of linked list */ + new = &new_sl->state; + err = copy_verifier_state(new, cur); + if (err) { + free_verifier_state(new, false); + kfree(new_sl); + return err; + } + new->insn_idx = insn_idx; + WARN_ONCE(new->branches != 1, + "BUG is_state_visited:branches_to_explore=%d insn %d\n", new->branches, insn_idx); + + cur->parent = new; + cur->first_insn_idx = insn_idx; + cur->dfs_depth = new->dfs_depth + 1; + clear_jmp_history(cur); + new_sl->next = *explored_state(env, insn_idx); + *explored_state(env, insn_idx) = new_sl; + /* connect new state to parentage chain. Current frame needs all + * registers connected. Only r6 - r9 of the callers are alive (pushed + * to the stack implicitly by JITs) so in callers' frames connect just + * r6 - r9 as an optimization. Callers will have r1 - r5 connected to + * the state of the call instruction (with WRITTEN set), and r0 comes + * from callee with its full parentage chain, anyway. + */ + /* clear write marks in current state: the writes we did are not writes + * our child did, so they don't screen off its reads from us. + * (There are no read marks in current state, because reads always mark + * their parent and current state never has children yet. Only + * explored_states can get read marks.) + */ + for (j = 0; j <= cur->curframe; j++) { + for (i = j < cur->curframe ? BPF_REG_6 : 0; i < BPF_REG_FP; i++) + cur->frame[j]->regs[i].parent = &new->frame[j]->regs[i]; + for (i = 0; i < BPF_REG_FP; i++) + cur->frame[j]->regs[i].live = REG_LIVE_NONE; + } + + /* all stack frames are accessible from callee, clear them all */ + for (j = 0; j <= cur->curframe; j++) { + struct bpf_func_state *frame = cur->frame[j]; + struct bpf_func_state *newframe = new->frame[j]; + + for (i = 0; i < frame->allocated_stack / BPF_REG_SIZE; i++) { + frame->stack[i].spilled_ptr.live = REG_LIVE_NONE; + frame->stack[i].spilled_ptr.parent = + &newframe->stack[i].spilled_ptr; + } + } + return 0; +} + +/* Return true if it's OK to have the same insn return a different type. */ +static bool reg_type_mismatch_ok(enum bpf_reg_type type) +{ + switch (base_type(type)) { + case PTR_TO_CTX: + case PTR_TO_SOCKET: + case PTR_TO_SOCK_COMMON: + case PTR_TO_TCP_SOCK: + case PTR_TO_XDP_SOCK: + case PTR_TO_BTF_ID: + return false; + default: + return true; + } +} + +/* If an instruction was previously used with particular pointer types, then we + * need to be careful to avoid cases such as the below, where it may be ok + * for one branch accessing the pointer, but not ok for the other branch: + * + * R1 = sock_ptr + * goto X; + * ... + * R1 = some_other_valid_ptr; + * goto X; + * ... + * R2 = *(u32 *)(R1 + 0); + */ +static bool reg_type_mismatch(enum bpf_reg_type src, enum bpf_reg_type prev) +{ + return src != prev && (!reg_type_mismatch_ok(src) || + !reg_type_mismatch_ok(prev)); +} + +static int save_aux_ptr_type(struct bpf_verifier_env *env, enum bpf_reg_type type, + bool allow_trust_missmatch) +{ + enum bpf_reg_type *prev_type = &env->insn_aux_data[env->insn_idx].ptr_type; + + if (*prev_type == NOT_INIT) { + /* Saw a valid insn + * dst_reg = *(u32 *)(src_reg + off) + * save type to validate intersecting paths + */ + *prev_type = type; + } else if (reg_type_mismatch(type, *prev_type)) { + /* Abuser program is trying to use the same insn + * dst_reg = *(u32*) (src_reg + off) + * with different pointer types: + * src_reg == ctx in one branch and + * src_reg == stack|map in some other branch. + * Reject it. + */ + if (allow_trust_missmatch && + base_type(type) == PTR_TO_BTF_ID && + base_type(*prev_type) == PTR_TO_BTF_ID) { + /* + * Have to support a use case when one path through + * the program yields TRUSTED pointer while another + * is UNTRUSTED. Fallback to UNTRUSTED to generate + * BPF_PROBE_MEM/BPF_PROBE_MEMSX. + */ + *prev_type = PTR_TO_BTF_ID | PTR_UNTRUSTED; + } else { + verbose(env, "same insn cannot be used with different pointers\n"); + return -EINVAL; + } + } + + return 0; +} + +static int do_check(struct bpf_verifier_env *env) +{ + bool pop_log = !(env->log.level & BPF_LOG_LEVEL2); + struct bpf_verifier_state *state = env->cur_state; + struct bpf_insn *insns = env->prog->insnsi; + struct bpf_reg_state *regs; + int insn_cnt = env->prog->len; + bool do_print_state = false; + int prev_insn_idx = -1; + + for (;;) { + struct bpf_insn *insn; + u8 class; + int err; + + env->prev_insn_idx = prev_insn_idx; + if (env->insn_idx >= insn_cnt) { + verbose(env, "invalid insn idx %d insn_cnt %d\n", + env->insn_idx, insn_cnt); + return -EFAULT; + } + + insn = &insns[env->insn_idx]; + class = BPF_CLASS(insn->code); + + if (++env->insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) { + verbose(env, + "BPF program is too large. Processed %d insn\n", + env->insn_processed); + return -E2BIG; + } + + state->last_insn_idx = env->prev_insn_idx; + + if (is_prune_point(env, env->insn_idx)) { + err = is_state_visited(env, env->insn_idx); + if (err < 0) + return err; + if (err == 1) { + /* found equivalent state, can prune the search */ + if (env->log.level & BPF_LOG_LEVEL) { + if (do_print_state) + verbose(env, "\nfrom %d to %d%s: safe\n", + env->prev_insn_idx, env->insn_idx, + env->cur_state->speculative ? + " (speculative execution)" : ""); + else + verbose(env, "%d: safe\n", env->insn_idx); + } + goto process_bpf_exit; + } + } + + if (is_jmp_point(env, env->insn_idx)) { + err = push_jmp_history(env, state); + if (err) + return err; + } + + if (signal_pending(current)) + return -EAGAIN; + + if (need_resched()) + cond_resched(); + + if (env->log.level & BPF_LOG_LEVEL2 && do_print_state) { + verbose(env, "\nfrom %d to %d%s:", + env->prev_insn_idx, env->insn_idx, + env->cur_state->speculative ? + " (speculative execution)" : ""); + print_verifier_state(env, state->frame[state->curframe], true); + do_print_state = false; + } + + if (env->log.level & BPF_LOG_LEVEL) { + const struct bpf_insn_cbs cbs = { + .cb_call = disasm_kfunc_name, + .cb_print = verbose, + .private_data = env, + }; + + if (verifier_state_scratched(env)) + print_insn_state(env, state->frame[state->curframe]); + + verbose_linfo(env, env->insn_idx, "; "); + env->prev_log_pos = env->log.end_pos; + verbose(env, "%d: ", env->insn_idx); + print_bpf_insn(&cbs, insn, env->allow_ptr_leaks); + env->prev_insn_print_pos = env->log.end_pos - env->prev_log_pos; + env->prev_log_pos = env->log.end_pos; + } + + if (bpf_prog_is_offloaded(env->prog->aux)) { + err = bpf_prog_offload_verify_insn(env, env->insn_idx, + env->prev_insn_idx); + if (err) + return err; + } + + regs = cur_regs(env); + sanitize_mark_insn_seen(env); + prev_insn_idx = env->insn_idx; + + if (class == BPF_ALU || class == BPF_ALU64) { + err = check_alu_op(env, insn); + if (err) + return err; + + } else if (class == BPF_LDX) { + enum bpf_reg_type src_reg_type; + + /* check for reserved fields is already done */ + + /* check src operand */ + err = check_reg_arg(env, insn->src_reg, SRC_OP); + if (err) + return err; + + err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK); + if (err) + return err; + + src_reg_type = regs[insn->src_reg].type; + + /* check that memory (src_reg + off) is readable, + * the state of dst_reg will be updated by this func + */ + err = check_mem_access(env, env->insn_idx, insn->src_reg, + insn->off, BPF_SIZE(insn->code), + BPF_READ, insn->dst_reg, false, + BPF_MODE(insn->code) == BPF_MEMSX); + if (err) + return err; + + err = save_aux_ptr_type(env, src_reg_type, true); + if (err) + return err; + } else if (class == BPF_STX) { + enum bpf_reg_type dst_reg_type; + + if (BPF_MODE(insn->code) == BPF_ATOMIC) { + err = check_atomic(env, env->insn_idx, insn); + if (err) + return err; + env->insn_idx++; + continue; + } + + if (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0) { + verbose(env, "BPF_STX uses reserved fields\n"); + return -EINVAL; + } + + /* check src1 operand */ + err = check_reg_arg(env, insn->src_reg, SRC_OP); + if (err) + return err; + /* check src2 operand */ + err = check_reg_arg(env, insn->dst_reg, SRC_OP); + if (err) + return err; + + dst_reg_type = regs[insn->dst_reg].type; + + /* check that memory (dst_reg + off) is writeable */ + err = check_mem_access(env, env->insn_idx, insn->dst_reg, + insn->off, BPF_SIZE(insn->code), + BPF_WRITE, insn->src_reg, false, false); + if (err) + return err; + + err = save_aux_ptr_type(env, dst_reg_type, false); + if (err) + return err; + } else if (class == BPF_ST) { + enum bpf_reg_type dst_reg_type; + + if (BPF_MODE(insn->code) != BPF_MEM || + insn->src_reg != BPF_REG_0) { + verbose(env, "BPF_ST uses reserved fields\n"); + return -EINVAL; + } + /* check src operand */ + err = check_reg_arg(env, insn->dst_reg, SRC_OP); + if (err) + return err; + + dst_reg_type = regs[insn->dst_reg].type; + + /* check that memory (dst_reg + off) is writeable */ + err = check_mem_access(env, env->insn_idx, insn->dst_reg, + insn->off, BPF_SIZE(insn->code), + BPF_WRITE, -1, false, false); + if (err) + return err; + + err = save_aux_ptr_type(env, dst_reg_type, false); + if (err) + return err; + } else if (class == BPF_JMP || class == BPF_JMP32) { + u8 opcode = BPF_OP(insn->code); + + env->jmps_processed++; + if (opcode == BPF_CALL) { + if (BPF_SRC(insn->code) != BPF_K || + (insn->src_reg != BPF_PSEUDO_KFUNC_CALL + && insn->off != 0) || + (insn->src_reg != BPF_REG_0 && + insn->src_reg != BPF_PSEUDO_CALL && + insn->src_reg != BPF_PSEUDO_KFUNC_CALL) || + insn->dst_reg != BPF_REG_0 || + class == BPF_JMP32) { + verbose(env, "BPF_CALL uses reserved fields\n"); + return -EINVAL; + } + + if (env->cur_state->active_lock.ptr) { + if ((insn->src_reg == BPF_REG_0 && insn->imm != BPF_FUNC_spin_unlock) || + (insn->src_reg == BPF_PSEUDO_CALL) || + (insn->src_reg == BPF_PSEUDO_KFUNC_CALL && + (insn->off != 0 || !is_bpf_graph_api_kfunc(insn->imm)))) { + verbose(env, "function calls are not allowed while holding a lock\n"); + return -EINVAL; + } + } + if (insn->src_reg == BPF_PSEUDO_CALL) + err = check_func_call(env, insn, &env->insn_idx); + else if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) + err = check_kfunc_call(env, insn, &env->insn_idx); + else + err = check_helper_call(env, insn, &env->insn_idx); + if (err) + return err; + + mark_reg_scratched(env, BPF_REG_0); + } else if (opcode == BPF_JA) { + if (BPF_SRC(insn->code) != BPF_K || + insn->src_reg != BPF_REG_0 || + insn->dst_reg != BPF_REG_0 || + (class == BPF_JMP && insn->imm != 0) || + (class == BPF_JMP32 && insn->off != 0)) { + verbose(env, "BPF_JA uses reserved fields\n"); + return -EINVAL; + } + + if (class == BPF_JMP) + env->insn_idx += insn->off + 1; + else + env->insn_idx += insn->imm + 1; + continue; + + } else if (opcode == BPF_EXIT) { + if (BPF_SRC(insn->code) != BPF_K || + insn->imm != 0 || + insn->src_reg != BPF_REG_0 || + insn->dst_reg != BPF_REG_0 || + class == BPF_JMP32) { + verbose(env, "BPF_EXIT uses reserved fields\n"); + return -EINVAL; + } + + if (env->cur_state->active_lock.ptr && + !in_rbtree_lock_required_cb(env)) { + verbose(env, "bpf_spin_unlock is missing\n"); + return -EINVAL; + } + + if (env->cur_state->active_rcu_lock && + !in_rbtree_lock_required_cb(env)) { + verbose(env, "bpf_rcu_read_unlock is missing\n"); + return -EINVAL; + } + + /* We must do check_reference_leak here before + * prepare_func_exit to handle the case when + * state->curframe > 0, it may be a callback + * function, for which reference_state must + * match caller reference state when it exits. + */ + err = check_reference_leak(env); + if (err) + return err; + + if (state->curframe) { + /* exit from nested function */ + err = prepare_func_exit(env, &env->insn_idx); + if (err) + return err; + do_print_state = true; + continue; + } + + err = check_return_code(env); + if (err) + return err; +process_bpf_exit: + mark_verifier_state_scratched(env); + update_branch_counts(env, env->cur_state); + err = pop_stack(env, &prev_insn_idx, + &env->insn_idx, pop_log); + if (err < 0) { + if (err != -ENOENT) + return err; + break; + } else { + do_print_state = true; + continue; + } + } else { + err = check_cond_jmp_op(env, insn, &env->insn_idx); + if (err) + return err; + } + } else if (class == BPF_LD) { + u8 mode = BPF_MODE(insn->code); + + if (mode == BPF_ABS || mode == BPF_IND) { + err = check_ld_abs(env, insn); + if (err) + return err; + + } else if (mode == BPF_IMM) { + err = check_ld_imm(env, insn); + if (err) + return err; + + env->insn_idx++; + sanitize_mark_insn_seen(env); + } else { + verbose(env, "invalid BPF_LD mode\n"); + return -EINVAL; + } + } else { + verbose(env, "unknown insn class %d\n", class); + return -EINVAL; + } + + env->insn_idx++; + } + + return 0; +} + +static int find_btf_percpu_datasec(struct btf *btf) +{ + const struct btf_type *t; + const char *tname; + int i, n; + + /* + * Both vmlinux and module each have their own ".data..percpu" + * DATASECs in BTF. So for module's case, we need to skip vmlinux BTF + * types to look at only module's own BTF types. + */ + n = btf_nr_types(btf); + if (btf_is_module(btf)) + i = btf_nr_types(btf_vmlinux); + else + i = 1; + + for(; i < n; i++) { + t = btf_type_by_id(btf, i); + if (BTF_INFO_KIND(t->info) != BTF_KIND_DATASEC) + continue; + + tname = btf_name_by_offset(btf, t->name_off); + if (!strcmp(tname, ".data..percpu")) + return i; + } + + return -ENOENT; +} + +/* replace pseudo btf_id with kernel symbol address */ +static int check_pseudo_btf_id(struct bpf_verifier_env *env, + struct bpf_insn *insn, + struct bpf_insn_aux_data *aux) +{ + const struct btf_var_secinfo *vsi; + const struct btf_type *datasec; + struct btf_mod_pair *btf_mod; + const struct btf_type *t; + const char *sym_name; + bool percpu = false; + u32 type, id = insn->imm; + struct btf *btf; + s32 datasec_id; + u64 addr; + int i, btf_fd, err; + + btf_fd = insn[1].imm; + if (btf_fd) { + btf = btf_get_by_fd(btf_fd); + if (IS_ERR(btf)) { + verbose(env, "invalid module BTF object FD specified.\n"); + return -EINVAL; + } + } else { + if (!btf_vmlinux) { + verbose(env, "kernel is missing BTF, make sure CONFIG_DEBUG_INFO_BTF=y is specified in Kconfig.\n"); + return -EINVAL; + } + btf = btf_vmlinux; + btf_get(btf); + } + + t = btf_type_by_id(btf, id); + if (!t) { + verbose(env, "ldimm64 insn specifies invalid btf_id %d.\n", id); + err = -ENOENT; + goto err_put; + } + + if (!btf_type_is_var(t) && !btf_type_is_func(t)) { + verbose(env, "pseudo btf_id %d in ldimm64 isn't KIND_VAR or KIND_FUNC\n", id); + err = -EINVAL; + goto err_put; + } + + sym_name = btf_name_by_offset(btf, t->name_off); + addr = kallsyms_lookup_name(sym_name); + if (!addr) { + verbose(env, "ldimm64 failed to find the address for kernel symbol '%s'.\n", + sym_name); + err = -ENOENT; + goto err_put; + } + insn[0].imm = (u32)addr; + insn[1].imm = addr >> 32; + + if (btf_type_is_func(t)) { + aux->btf_var.reg_type = PTR_TO_MEM | MEM_RDONLY; + aux->btf_var.mem_size = 0; + goto check_btf; + } + + datasec_id = find_btf_percpu_datasec(btf); + if (datasec_id > 0) { + datasec = btf_type_by_id(btf, datasec_id); + for_each_vsi(i, datasec, vsi) { + if (vsi->type == id) { + percpu = true; + break; + } + } + } + + type = t->type; + t = btf_type_skip_modifiers(btf, type, NULL); + if (percpu) { + aux->btf_var.reg_type = PTR_TO_BTF_ID | MEM_PERCPU; + aux->btf_var.btf = btf; + aux->btf_var.btf_id = type; + } else if (!btf_type_is_struct(t)) { + const struct btf_type *ret; + const char *tname; + u32 tsize; + + /* resolve the type size of ksym. */ + ret = btf_resolve_size(btf, t, &tsize); + if (IS_ERR(ret)) { + tname = btf_name_by_offset(btf, t->name_off); + verbose(env, "ldimm64 unable to resolve the size of type '%s': %ld\n", + tname, PTR_ERR(ret)); + err = -EINVAL; + goto err_put; + } + aux->btf_var.reg_type = PTR_TO_MEM | MEM_RDONLY; + aux->btf_var.mem_size = tsize; + } else { + aux->btf_var.reg_type = PTR_TO_BTF_ID; + aux->btf_var.btf = btf; + aux->btf_var.btf_id = type; + } +check_btf: + /* check whether we recorded this BTF (and maybe module) already */ + for (i = 0; i < env->used_btf_cnt; i++) { + if (env->used_btfs[i].btf == btf) { + btf_put(btf); + return 0; + } + } + + if (env->used_btf_cnt >= MAX_USED_BTFS) { + err = -E2BIG; + goto err_put; + } + + btf_mod = &env->used_btfs[env->used_btf_cnt]; + btf_mod->btf = btf; + btf_mod->module = NULL; + + /* if we reference variables from kernel module, bump its refcount */ + if (btf_is_module(btf)) { + btf_mod->module = btf_try_get_module(btf); + if (!btf_mod->module) { + err = -ENXIO; + goto err_put; + } + } + + env->used_btf_cnt++; + + return 0; +err_put: + btf_put(btf); + return err; +} + +static bool is_tracing_prog_type(enum bpf_prog_type type) +{ + switch (type) { + case BPF_PROG_TYPE_KPROBE: + case BPF_PROG_TYPE_TRACEPOINT: + case BPF_PROG_TYPE_PERF_EVENT: + case BPF_PROG_TYPE_RAW_TRACEPOINT: + case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE: + return true; + default: + return false; + } +} + +static int check_map_prog_compatibility(struct bpf_verifier_env *env, + struct bpf_map *map, + struct bpf_prog *prog) + +{ + enum bpf_prog_type prog_type = resolve_prog_type(prog); + + if (btf_record_has_field(map->record, BPF_LIST_HEAD) || + btf_record_has_field(map->record, BPF_RB_ROOT)) { + if (is_tracing_prog_type(prog_type)) { + verbose(env, "tracing progs cannot use bpf_{list_head,rb_root} yet\n"); + return -EINVAL; + } + } + + if (btf_record_has_field(map->record, BPF_SPIN_LOCK)) { + if (prog_type == BPF_PROG_TYPE_SOCKET_FILTER) { + verbose(env, "socket filter progs cannot use bpf_spin_lock yet\n"); + return -EINVAL; + } + + if (is_tracing_prog_type(prog_type)) { + verbose(env, "tracing progs cannot use bpf_spin_lock yet\n"); + return -EINVAL; + } + } + + if (btf_record_has_field(map->record, BPF_TIMER)) { + if (is_tracing_prog_type(prog_type)) { + verbose(env, "tracing progs cannot use bpf_timer yet\n"); + return -EINVAL; + } + } + + if ((bpf_prog_is_offloaded(prog->aux) || bpf_map_is_offloaded(map)) && + !bpf_offload_prog_map_match(prog, map)) { + verbose(env, "offload device mismatch between prog and map\n"); + return -EINVAL; + } + + if (map->map_type == BPF_MAP_TYPE_STRUCT_OPS) { + verbose(env, "bpf_struct_ops map cannot be used in prog\n"); + return -EINVAL; + } + + if (prog->aux->sleepable) + switch (map->map_type) { + case BPF_MAP_TYPE_HASH: + case BPF_MAP_TYPE_LRU_HASH: + case BPF_MAP_TYPE_ARRAY: + case BPF_MAP_TYPE_PERCPU_HASH: + case BPF_MAP_TYPE_PERCPU_ARRAY: + case BPF_MAP_TYPE_LRU_PERCPU_HASH: + case BPF_MAP_TYPE_ARRAY_OF_MAPS: + case BPF_MAP_TYPE_HASH_OF_MAPS: + case BPF_MAP_TYPE_RINGBUF: + case BPF_MAP_TYPE_USER_RINGBUF: + case BPF_MAP_TYPE_INODE_STORAGE: + case BPF_MAP_TYPE_SK_STORAGE: + case BPF_MAP_TYPE_TASK_STORAGE: + case BPF_MAP_TYPE_CGRP_STORAGE: + break; + default: + verbose(env, + "Sleepable programs can only use array, hash, ringbuf and local storage maps\n"); + return -EINVAL; + } + + return 0; +} + +static bool bpf_map_is_cgroup_storage(struct bpf_map *map) +{ + return (map->map_type == BPF_MAP_TYPE_CGROUP_STORAGE || + map->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE); +} + +/* find and rewrite pseudo imm in ld_imm64 instructions: + * + * 1. if it accesses map FD, replace it with actual map pointer. + * 2. if it accesses btf_id of a VAR, replace it with pointer to the var. + * + * NOTE: btf_vmlinux is required for converting pseudo btf_id. + */ +static int resolve_pseudo_ldimm64(struct bpf_verifier_env *env) +{ + struct bpf_insn *insn = env->prog->insnsi; + int insn_cnt = env->prog->len; + int i, j, err; + + err = bpf_prog_calc_tag(env->prog); + if (err) + return err; + + for (i = 0; i < insn_cnt; i++, insn++) { + if (BPF_CLASS(insn->code) == BPF_LDX && + ((BPF_MODE(insn->code) != BPF_MEM && BPF_MODE(insn->code) != BPF_MEMSX) || + insn->imm != 0)) { + verbose(env, "BPF_LDX uses reserved fields\n"); + return -EINVAL; + } + + if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) { + struct bpf_insn_aux_data *aux; + struct bpf_map *map; + struct fd f; + u64 addr; + u32 fd; + + if (i == insn_cnt - 1 || insn[1].code != 0 || + insn[1].dst_reg != 0 || insn[1].src_reg != 0 || + insn[1].off != 0) { + verbose(env, "invalid bpf_ld_imm64 insn\n"); + return -EINVAL; + } + + if (insn[0].src_reg == 0) + /* valid generic load 64-bit imm */ + goto next_insn; + + if (insn[0].src_reg == BPF_PSEUDO_BTF_ID) { + aux = &env->insn_aux_data[i]; + err = check_pseudo_btf_id(env, insn, aux); + if (err) + return err; + goto next_insn; + } + + if (insn[0].src_reg == BPF_PSEUDO_FUNC) { + aux = &env->insn_aux_data[i]; + aux->ptr_type = PTR_TO_FUNC; + goto next_insn; + } + + /* In final convert_pseudo_ld_imm64() step, this is + * converted into regular 64-bit imm load insn. + */ + switch (insn[0].src_reg) { + case BPF_PSEUDO_MAP_VALUE: + case BPF_PSEUDO_MAP_IDX_VALUE: + break; + case BPF_PSEUDO_MAP_FD: + case BPF_PSEUDO_MAP_IDX: + if (insn[1].imm == 0) + break; + fallthrough; + default: + verbose(env, "unrecognized bpf_ld_imm64 insn\n"); + return -EINVAL; + } + + switch (insn[0].src_reg) { + case BPF_PSEUDO_MAP_IDX_VALUE: + case BPF_PSEUDO_MAP_IDX: + if (bpfptr_is_null(env->fd_array)) { + verbose(env, "fd_idx without fd_array is invalid\n"); + return -EPROTO; + } + if (copy_from_bpfptr_offset(&fd, env->fd_array, + insn[0].imm * sizeof(fd), + sizeof(fd))) + return -EFAULT; + break; + default: + fd = insn[0].imm; + break; + } + + f = fdget(fd); + map = __bpf_map_get(f); + if (IS_ERR(map)) { + verbose(env, "fd %d is not pointing to valid bpf_map\n", + insn[0].imm); + return PTR_ERR(map); + } + + err = check_map_prog_compatibility(env, map, env->prog); + if (err) { + fdput(f); + return err; + } + + aux = &env->insn_aux_data[i]; + if (insn[0].src_reg == BPF_PSEUDO_MAP_FD || + insn[0].src_reg == BPF_PSEUDO_MAP_IDX) { + addr = (unsigned long)map; + } else { + u32 off = insn[1].imm; + + if (off >= BPF_MAX_VAR_OFF) { + verbose(env, "direct value offset of %u is not allowed\n", off); + fdput(f); + return -EINVAL; + } + + if (!map->ops->map_direct_value_addr) { + verbose(env, "no direct value access support for this map type\n"); + fdput(f); + return -EINVAL; + } + + err = map->ops->map_direct_value_addr(map, &addr, off); + if (err) { + verbose(env, "invalid access to map value pointer, value_size=%u off=%u\n", + map->value_size, off); + fdput(f); + return err; + } + + aux->map_off = off; + addr += off; + } + + insn[0].imm = (u32)addr; + insn[1].imm = addr >> 32; + + /* check whether we recorded this map already */ + for (j = 0; j < env->used_map_cnt; j++) { + if (env->used_maps[j] == map) { + aux->map_index = j; + fdput(f); + goto next_insn; + } + } + + if (env->used_map_cnt >= MAX_USED_MAPS) { + fdput(f); + return -E2BIG; + } + + /* hold the map. If the program is rejected by verifier, + * the map will be released by release_maps() or it + * will be used by the valid program until it's unloaded + * and all maps are released in free_used_maps() + */ + bpf_map_inc(map); + + aux->map_index = env->used_map_cnt; + env->used_maps[env->used_map_cnt++] = map; + + if (bpf_map_is_cgroup_storage(map) && + bpf_cgroup_storage_assign(env->prog->aux, map)) { + verbose(env, "only one cgroup storage of each type is allowed\n"); + fdput(f); + return -EBUSY; + } + + fdput(f); +next_insn: + insn++; + i++; + continue; + } + + /* Basic sanity check before we invest more work here. */ + if (!bpf_opcode_in_insntable(insn->code)) { + verbose(env, "unknown opcode %02x\n", insn->code); + return -EINVAL; + } + } + + /* now all pseudo BPF_LD_IMM64 instructions load valid + * 'struct bpf_map *' into a register instead of user map_fd. + * These pointers will be used later by verifier to validate map access. + */ + return 0; +} + +/* drop refcnt of maps used by the rejected program */ +static void release_maps(struct bpf_verifier_env *env) +{ + __bpf_free_used_maps(env->prog->aux, env->used_maps, + env->used_map_cnt); +} + +/* drop refcnt of maps used by the rejected program */ +static void release_btfs(struct bpf_verifier_env *env) +{ + __bpf_free_used_btfs(env->prog->aux, env->used_btfs, + env->used_btf_cnt); +} + +/* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */ +static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env) +{ + struct bpf_insn *insn = env->prog->insnsi; + int insn_cnt = env->prog->len; + int i; + + for (i = 0; i < insn_cnt; i++, insn++) { + if (insn->code != (BPF_LD | BPF_IMM | BPF_DW)) + continue; + if (insn->src_reg == BPF_PSEUDO_FUNC) + continue; + insn->src_reg = 0; + } +} + +/* single env->prog->insni[off] instruction was replaced with the range + * insni[off, off + cnt). Adjust corresponding insn_aux_data by copying + * [0, off) and [off, end) to new locations, so the patched range stays zero + */ +static void adjust_insn_aux_data(struct bpf_verifier_env *env, + struct bpf_insn_aux_data *new_data, + struct bpf_prog *new_prog, u32 off, u32 cnt) +{ + struct bpf_insn_aux_data *old_data = env->insn_aux_data; + struct bpf_insn *insn = new_prog->insnsi; + u32 old_seen = old_data[off].seen; + u32 prog_len; + int i; + + /* aux info at OFF always needs adjustment, no matter fast path + * (cnt == 1) is taken or not. There is no guarantee INSN at OFF is the + * original insn at old prog. + */ + old_data[off].zext_dst = insn_has_def32(env, insn + off + cnt - 1); + + if (cnt == 1) + return; + prog_len = new_prog->len; + + memcpy(new_data, old_data, sizeof(struct bpf_insn_aux_data) * off); + memcpy(new_data + off + cnt - 1, old_data + off, + sizeof(struct bpf_insn_aux_data) * (prog_len - off - cnt + 1)); + for (i = off; i < off + cnt - 1; i++) { + /* Expand insni[off]'s seen count to the patched range. */ + new_data[i].seen = old_seen; + new_data[i].zext_dst = insn_has_def32(env, insn + i); + } + env->insn_aux_data = new_data; + vfree(old_data); +} + +static void adjust_subprog_starts(struct bpf_verifier_env *env, u32 off, u32 len) +{ + int i; + + if (len == 1) + return; + /* NOTE: fake 'exit' subprog should be updated as well. */ + for (i = 0; i <= env->subprog_cnt; i++) { + if (env->subprog_info[i].start <= off) + continue; + env->subprog_info[i].start += len - 1; + } +} + +static void adjust_poke_descs(struct bpf_prog *prog, u32 off, u32 len) +{ + struct bpf_jit_poke_descriptor *tab = prog->aux->poke_tab; + int i, sz = prog->aux->size_poke_tab; + struct bpf_jit_poke_descriptor *desc; + + for (i = 0; i < sz; i++) { + desc = &tab[i]; + if (desc->insn_idx <= off) + continue; + desc->insn_idx += len - 1; + } +} + +static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 off, + const struct bpf_insn *patch, u32 len) +{ + struct bpf_prog *new_prog; + struct bpf_insn_aux_data *new_data = NULL; + + if (len > 1) { + new_data = vzalloc(array_size(env->prog->len + len - 1, + sizeof(struct bpf_insn_aux_data))); + if (!new_data) + return NULL; + } + + new_prog = bpf_patch_insn_single(env->prog, off, patch, len); + if (IS_ERR(new_prog)) { + if (PTR_ERR(new_prog) == -ERANGE) + verbose(env, + "insn %d cannot be patched due to 16-bit range\n", + env->insn_aux_data[off].orig_idx); + vfree(new_data); + return NULL; + } + adjust_insn_aux_data(env, new_data, new_prog, off, len); + adjust_subprog_starts(env, off, len); + adjust_poke_descs(new_prog, off, len); + return new_prog; +} + +static int adjust_subprog_starts_after_remove(struct bpf_verifier_env *env, + u32 off, u32 cnt) +{ + int i, j; + + /* find first prog starting at or after off (first to remove) */ + for (i = 0; i < env->subprog_cnt; i++) + if (env->subprog_info[i].start >= off) + break; + /* find first prog starting at or after off + cnt (first to stay) */ + for (j = i; j < env->subprog_cnt; j++) + if (env->subprog_info[j].start >= off + cnt) + break; + /* if j doesn't start exactly at off + cnt, we are just removing + * the front of previous prog + */ + if (env->subprog_info[j].start != off + cnt) + j--; + + if (j > i) { + struct bpf_prog_aux *aux = env->prog->aux; + int move; + + /* move fake 'exit' subprog as well */ + move = env->subprog_cnt + 1 - j; + + memmove(env->subprog_info + i, + env->subprog_info + j, + sizeof(*env->subprog_info) * move); + env->subprog_cnt -= j - i; + + /* remove func_info */ + if (aux->func_info) { + move = aux->func_info_cnt - j; + + memmove(aux->func_info + i, + aux->func_info + j, + sizeof(*aux->func_info) * move); + aux->func_info_cnt -= j - i; + /* func_info->insn_off is set after all code rewrites, + * in adjust_btf_func() - no need to adjust + */ + } + } else { + /* convert i from "first prog to remove" to "first to adjust" */ + if (env->subprog_info[i].start == off) + i++; + } + + /* update fake 'exit' subprog as well */ + for (; i <= env->subprog_cnt; i++) + env->subprog_info[i].start -= cnt; + + return 0; +} + +static int bpf_adj_linfo_after_remove(struct bpf_verifier_env *env, u32 off, + u32 cnt) +{ + struct bpf_prog *prog = env->prog; + u32 i, l_off, l_cnt, nr_linfo; + struct bpf_line_info *linfo; + + nr_linfo = prog->aux->nr_linfo; + if (!nr_linfo) + return 0; + + linfo = prog->aux->linfo; + + /* find first line info to remove, count lines to be removed */ + for (i = 0; i < nr_linfo; i++) + if (linfo[i].insn_off >= off) + break; + + l_off = i; + l_cnt = 0; + for (; i < nr_linfo; i++) + if (linfo[i].insn_off < off + cnt) + l_cnt++; + else + break; + + /* First live insn doesn't match first live linfo, it needs to "inherit" + * last removed linfo. prog is already modified, so prog->len == off + * means no live instructions after (tail of the program was removed). + */ + if (prog->len != off && l_cnt && + (i == nr_linfo || linfo[i].insn_off != off + cnt)) { + l_cnt--; + linfo[--i].insn_off = off + cnt; + } + + /* remove the line info which refer to the removed instructions */ + if (l_cnt) { + memmove(linfo + l_off, linfo + i, + sizeof(*linfo) * (nr_linfo - i)); + + prog->aux->nr_linfo -= l_cnt; + nr_linfo = prog->aux->nr_linfo; + } + + /* pull all linfo[i].insn_off >= off + cnt in by cnt */ + for (i = l_off; i < nr_linfo; i++) + linfo[i].insn_off -= cnt; + + /* fix up all subprogs (incl. 'exit') which start >= off */ + for (i = 0; i <= env->subprog_cnt; i++) + if (env->subprog_info[i].linfo_idx > l_off) { + /* program may have started in the removed region but + * may not be fully removed + */ + if (env->subprog_info[i].linfo_idx >= l_off + l_cnt) + env->subprog_info[i].linfo_idx -= l_cnt; + else + env->subprog_info[i].linfo_idx = l_off; + } + + return 0; +} + +static int verifier_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt) +{ + struct bpf_insn_aux_data *aux_data = env->insn_aux_data; + unsigned int orig_prog_len = env->prog->len; + int err; + + if (bpf_prog_is_offloaded(env->prog->aux)) + bpf_prog_offload_remove_insns(env, off, cnt); + + err = bpf_remove_insns(env->prog, off, cnt); + if (err) + return err; + + err = adjust_subprog_starts_after_remove(env, off, cnt); + if (err) + return err; + + err = bpf_adj_linfo_after_remove(env, off, cnt); + if (err) + return err; + + memmove(aux_data + off, aux_data + off + cnt, + sizeof(*aux_data) * (orig_prog_len - off - cnt)); + + return 0; +} + +/* The verifier does more data flow analysis than llvm and will not + * explore branches that are dead at run time. Malicious programs can + * have dead code too. Therefore replace all dead at-run-time code + * with 'ja -1'. + * + * Just nops are not optimal, e.g. if they would sit at the end of the + * program and through another bug we would manage to jump there, then + * we'd execute beyond program memory otherwise. Returning exception + * code also wouldn't work since we can have subprogs where the dead + * code could be located. + */ +static void sanitize_dead_code(struct bpf_verifier_env *env) +{ + struct bpf_insn_aux_data *aux_data = env->insn_aux_data; + struct bpf_insn trap = BPF_JMP_IMM(BPF_JA, 0, 0, -1); + struct bpf_insn *insn = env->prog->insnsi; + const int insn_cnt = env->prog->len; + int i; + + for (i = 0; i < insn_cnt; i++) { + if (aux_data[i].seen) + continue; + memcpy(insn + i, &trap, sizeof(trap)); + aux_data[i].zext_dst = false; + } +} + +static bool insn_is_cond_jump(u8 code) +{ + u8 op; + + op = BPF_OP(code); + if (BPF_CLASS(code) == BPF_JMP32) + return op != BPF_JA; + + if (BPF_CLASS(code) != BPF_JMP) + return false; + + return op != BPF_JA && op != BPF_EXIT && op != BPF_CALL; +} + +static void opt_hard_wire_dead_code_branches(struct bpf_verifier_env *env) +{ + struct bpf_insn_aux_data *aux_data = env->insn_aux_data; + struct bpf_insn ja = BPF_JMP_IMM(BPF_JA, 0, 0, 0); + struct bpf_insn *insn = env->prog->insnsi; + const int insn_cnt = env->prog->len; + int i; + + for (i = 0; i < insn_cnt; i++, insn++) { + if (!insn_is_cond_jump(insn->code)) + continue; + + if (!aux_data[i + 1].seen) + ja.off = insn->off; + else if (!aux_data[i + 1 + insn->off].seen) + ja.off = 0; + else + continue; + + if (bpf_prog_is_offloaded(env->prog->aux)) + bpf_prog_offload_replace_insn(env, i, &ja); + + memcpy(insn, &ja, sizeof(ja)); + } +} + +static int opt_remove_dead_code(struct bpf_verifier_env *env) +{ + struct bpf_insn_aux_data *aux_data = env->insn_aux_data; + int insn_cnt = env->prog->len; + int i, err; + + for (i = 0; i < insn_cnt; i++) { + int j; + + j = 0; + while (i + j < insn_cnt && !aux_data[i + j].seen) + j++; + if (!j) + continue; + + err = verifier_remove_insns(env, i, j); + if (err) + return err; + insn_cnt = env->prog->len; + } + + return 0; +} + +static int opt_remove_nops(struct bpf_verifier_env *env) +{ + const struct bpf_insn ja = BPF_JMP_IMM(BPF_JA, 0, 0, 0); + struct bpf_insn *insn = env->prog->insnsi; + int insn_cnt = env->prog->len; + int i, err; + + for (i = 0; i < insn_cnt; i++) { + if (memcmp(&insn[i], &ja, sizeof(ja))) + continue; + + err = verifier_remove_insns(env, i, 1); + if (err) + return err; + insn_cnt--; + i--; + } + + return 0; +} + +static int opt_subreg_zext_lo32_rnd_hi32(struct bpf_verifier_env *env, + const union bpf_attr *attr) +{ + struct bpf_insn *patch, zext_patch[2], rnd_hi32_patch[4]; + struct bpf_insn_aux_data *aux = env->insn_aux_data; + int i, patch_len, delta = 0, len = env->prog->len; + struct bpf_insn *insns = env->prog->insnsi; + struct bpf_prog *new_prog; + bool rnd_hi32; + + rnd_hi32 = attr->prog_flags & BPF_F_TEST_RND_HI32; + zext_patch[1] = BPF_ZEXT_REG(0); + rnd_hi32_patch[1] = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, 0); + rnd_hi32_patch[2] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_AX, 32); + rnd_hi32_patch[3] = BPF_ALU64_REG(BPF_OR, 0, BPF_REG_AX); + for (i = 0; i < len; i++) { + int adj_idx = i + delta; + struct bpf_insn insn; + int load_reg; + + insn = insns[adj_idx]; + load_reg = insn_def_regno(&insn); + if (!aux[adj_idx].zext_dst) { + u8 code, class; + u32 imm_rnd; + + if (!rnd_hi32) + continue; + + code = insn.code; + class = BPF_CLASS(code); + if (load_reg == -1) + continue; + + /* NOTE: arg "reg" (the fourth one) is only used for + * BPF_STX + SRC_OP, so it is safe to pass NULL + * here. + */ + if (is_reg64(env, &insn, load_reg, NULL, DST_OP)) { + if (class == BPF_LD && + BPF_MODE(code) == BPF_IMM) + i++; + continue; + } + + /* ctx load could be transformed into wider load. */ + if (class == BPF_LDX && + aux[adj_idx].ptr_type == PTR_TO_CTX) + continue; + + imm_rnd = get_random_u32(); + rnd_hi32_patch[0] = insn; + rnd_hi32_patch[1].imm = imm_rnd; + rnd_hi32_patch[3].dst_reg = load_reg; + patch = rnd_hi32_patch; + patch_len = 4; + goto apply_patch_buffer; + } + + /* Add in an zero-extend instruction if a) the JIT has requested + * it or b) it's a CMPXCHG. + * + * The latter is because: BPF_CMPXCHG always loads a value into + * R0, therefore always zero-extends. However some archs' + * equivalent instruction only does this load when the + * comparison is successful. This detail of CMPXCHG is + * orthogonal to the general zero-extension behaviour of the + * CPU, so it's treated independently of bpf_jit_needs_zext. + */ + if (!bpf_jit_needs_zext() && !is_cmpxchg_insn(&insn)) + continue; + + /* Zero-extension is done by the caller. */ + if (bpf_pseudo_kfunc_call(&insn)) + continue; + + if (WARN_ON(load_reg == -1)) { + verbose(env, "verifier bug. zext_dst is set, but no reg is defined\n"); + return -EFAULT; + } + + zext_patch[0] = insn; + zext_patch[1].dst_reg = load_reg; + zext_patch[1].src_reg = load_reg; + patch = zext_patch; + patch_len = 2; +apply_patch_buffer: + new_prog = bpf_patch_insn_data(env, adj_idx, patch, patch_len); + if (!new_prog) + return -ENOMEM; + env->prog = new_prog; + insns = new_prog->insnsi; + aux = env->insn_aux_data; + delta += patch_len - 1; + } + + return 0; +} + +/* convert load instructions that access fields of a context type into a + * sequence of instructions that access fields of the underlying structure: + * struct __sk_buff -> struct sk_buff + * struct bpf_sock_ops -> struct sock + */ +static int convert_ctx_accesses(struct bpf_verifier_env *env) +{ + const struct bpf_verifier_ops *ops = env->ops; + int i, cnt, size, ctx_field_size, delta = 0; + const int insn_cnt = env->prog->len; + struct bpf_insn insn_buf[16], *insn; + u32 target_size, size_default, off; + struct bpf_prog *new_prog; + enum bpf_access_type type; + bool is_narrower_load; + + if (ops->gen_prologue || env->seen_direct_write) { + if (!ops->gen_prologue) { + verbose(env, "bpf verifier is misconfigured\n"); + return -EINVAL; + } + cnt = ops->gen_prologue(insn_buf, env->seen_direct_write, + env->prog); + if (cnt >= ARRAY_SIZE(insn_buf)) { + verbose(env, "bpf verifier is misconfigured\n"); + return -EINVAL; + } else if (cnt) { + new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt); + if (!new_prog) + return -ENOMEM; + + env->prog = new_prog; + delta += cnt - 1; + } + } + + if (bpf_prog_is_offloaded(env->prog->aux)) + return 0; + + insn = env->prog->insnsi + delta; + + for (i = 0; i < insn_cnt; i++, insn++) { + bpf_convert_ctx_access_t convert_ctx_access; + u8 mode; + + if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) || + insn->code == (BPF_LDX | BPF_MEM | BPF_H) || + insn->code == (BPF_LDX | BPF_MEM | BPF_W) || + insn->code == (BPF_LDX | BPF_MEM | BPF_DW) || + insn->code == (BPF_LDX | BPF_MEMSX | BPF_B) || + insn->code == (BPF_LDX | BPF_MEMSX | BPF_H) || + insn->code == (BPF_LDX | BPF_MEMSX | BPF_W)) { + type = BPF_READ; + } else if (insn->code == (BPF_STX | BPF_MEM | BPF_B) || + insn->code == (BPF_STX | BPF_MEM | BPF_H) || + insn->code == (BPF_STX | BPF_MEM | BPF_W) || + insn->code == (BPF_STX | BPF_MEM | BPF_DW) || + insn->code == (BPF_ST | BPF_MEM | BPF_B) || + insn->code == (BPF_ST | BPF_MEM | BPF_H) || + insn->code == (BPF_ST | BPF_MEM | BPF_W) || + insn->code == (BPF_ST | BPF_MEM | BPF_DW)) { + type = BPF_WRITE; + } else { + continue; + } + + if (type == BPF_WRITE && + env->insn_aux_data[i + delta].sanitize_stack_spill) { + struct bpf_insn patch[] = { + *insn, + BPF_ST_NOSPEC(), + }; + + cnt = ARRAY_SIZE(patch); + new_prog = bpf_patch_insn_data(env, i + delta, patch, cnt); + if (!new_prog) + return -ENOMEM; + + delta += cnt - 1; + env->prog = new_prog; + insn = new_prog->insnsi + i + delta; + continue; + } + + switch ((int)env->insn_aux_data[i + delta].ptr_type) { + case PTR_TO_CTX: + if (!ops->convert_ctx_access) + continue; + convert_ctx_access = ops->convert_ctx_access; + break; + case PTR_TO_SOCKET: + case PTR_TO_SOCK_COMMON: + convert_ctx_access = bpf_sock_convert_ctx_access; + break; + case PTR_TO_TCP_SOCK: + convert_ctx_access = bpf_tcp_sock_convert_ctx_access; + break; + case PTR_TO_XDP_SOCK: + convert_ctx_access = bpf_xdp_sock_convert_ctx_access; + break; + case PTR_TO_BTF_ID: + case PTR_TO_BTF_ID | PTR_UNTRUSTED: + /* PTR_TO_BTF_ID | MEM_ALLOC always has a valid lifetime, unlike + * PTR_TO_BTF_ID, and an active ref_obj_id, but the same cannot + * be said once it is marked PTR_UNTRUSTED, hence we must handle + * any faults for loads into such types. BPF_WRITE is disallowed + * for this case. + */ + case PTR_TO_BTF_ID | MEM_ALLOC | PTR_UNTRUSTED: + if (type == BPF_READ) { + if (BPF_MODE(insn->code) == BPF_MEM) + insn->code = BPF_LDX | BPF_PROBE_MEM | + BPF_SIZE((insn)->code); + else + insn->code = BPF_LDX | BPF_PROBE_MEMSX | + BPF_SIZE((insn)->code); + env->prog->aux->num_exentries++; + } + continue; + default: + continue; + } + + ctx_field_size = env->insn_aux_data[i + delta].ctx_field_size; + size = BPF_LDST_BYTES(insn); + mode = BPF_MODE(insn->code); + + /* If the read access is a narrower load of the field, + * convert to a 4/8-byte load, to minimum program type specific + * convert_ctx_access changes. If conversion is successful, + * we will apply proper mask to the result. + */ + is_narrower_load = size < ctx_field_size; + size_default = bpf_ctx_off_adjust_machine(ctx_field_size); + off = insn->off; + if (is_narrower_load) { + u8 size_code; + + if (type == BPF_WRITE) { + verbose(env, "bpf verifier narrow ctx access misconfigured\n"); + return -EINVAL; + } + + size_code = BPF_H; + if (ctx_field_size == 4) + size_code = BPF_W; + else if (ctx_field_size == 8) + size_code = BPF_DW; + + insn->off = off & ~(size_default - 1); + insn->code = BPF_LDX | BPF_MEM | size_code; + } + + target_size = 0; + cnt = convert_ctx_access(type, insn, insn_buf, env->prog, + &target_size); + if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf) || + (ctx_field_size && !target_size)) { + verbose(env, "bpf verifier is misconfigured\n"); + return -EINVAL; + } + + if (is_narrower_load && size < target_size) { + u8 shift = bpf_ctx_narrow_access_offset( + off, size, size_default) * 8; + if (shift && cnt + 1 >= ARRAY_SIZE(insn_buf)) { + verbose(env, "bpf verifier narrow ctx load misconfigured\n"); + return -EINVAL; + } + if (ctx_field_size <= 4) { + if (shift) + insn_buf[cnt++] = BPF_ALU32_IMM(BPF_RSH, + insn->dst_reg, + shift); + insn_buf[cnt++] = BPF_ALU32_IMM(BPF_AND, insn->dst_reg, + (1 << size * 8) - 1); + } else { + if (shift) + insn_buf[cnt++] = BPF_ALU64_IMM(BPF_RSH, + insn->dst_reg, + shift); + insn_buf[cnt++] = BPF_ALU32_IMM(BPF_AND, insn->dst_reg, + (1ULL << size * 8) - 1); + } + } + if (mode == BPF_MEMSX) + insn_buf[cnt++] = BPF_RAW_INSN(BPF_ALU64 | BPF_MOV | BPF_X, + insn->dst_reg, insn->dst_reg, + size * 8, 0); + + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); + if (!new_prog) + return -ENOMEM; + + delta += cnt - 1; + + /* keep walking new program and skip insns we just inserted */ + env->prog = new_prog; + insn = new_prog->insnsi + i + delta; + } + + return 0; +} + +static int jit_subprogs(struct bpf_verifier_env *env) +{ + struct bpf_prog *prog = env->prog, **func, *tmp; + int i, j, subprog_start, subprog_end = 0, len, subprog; + struct bpf_map *map_ptr; + struct bpf_insn *insn; + void *old_bpf_func; + int err, num_exentries; + + if (env->subprog_cnt <= 1) + return 0; + + for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) { + if (!bpf_pseudo_func(insn) && !bpf_pseudo_call(insn)) + continue; + + /* Upon error here we cannot fall back to interpreter but + * need a hard reject of the program. Thus -EFAULT is + * propagated in any case. + */ + subprog = find_subprog(env, i + insn->imm + 1); + if (subprog < 0) { + WARN_ONCE(1, "verifier bug. No program starts at insn %d\n", + i + insn->imm + 1); + return -EFAULT; + } + /* temporarily remember subprog id inside insn instead of + * aux_data, since next loop will split up all insns into funcs + */ + insn->off = subprog; + /* remember original imm in case JIT fails and fallback + * to interpreter will be needed + */ + env->insn_aux_data[i].call_imm = insn->imm; + /* point imm to __bpf_call_base+1 from JITs point of view */ + insn->imm = 1; + if (bpf_pseudo_func(insn)) + /* jit (e.g. x86_64) may emit fewer instructions + * if it learns a u32 imm is the same as a u64 imm. + * Force a non zero here. + */ + insn[1].imm = 1; + } + + err = bpf_prog_alloc_jited_linfo(prog); + if (err) + goto out_undo_insn; + + err = -ENOMEM; + func = kcalloc(env->subprog_cnt, sizeof(prog), GFP_KERNEL); + if (!func) + goto out_undo_insn; + + for (i = 0; i < env->subprog_cnt; i++) { + subprog_start = subprog_end; + subprog_end = env->subprog_info[i + 1].start; + + len = subprog_end - subprog_start; + /* bpf_prog_run() doesn't call subprogs directly, + * hence main prog stats include the runtime of subprogs. + * subprogs don't have IDs and not reachable via prog_get_next_id + * func[i]->stats will never be accessed and stays NULL + */ + func[i] = bpf_prog_alloc_no_stats(bpf_prog_size(len), GFP_USER); + if (!func[i]) + goto out_free; + memcpy(func[i]->insnsi, &prog->insnsi[subprog_start], + len * sizeof(struct bpf_insn)); + func[i]->type = prog->type; + func[i]->len = len; + if (bpf_prog_calc_tag(func[i])) + goto out_free; + func[i]->is_func = 1; + func[i]->aux->func_idx = i; + /* Below members will be freed only at prog->aux */ + func[i]->aux->btf = prog->aux->btf; + func[i]->aux->func_info = prog->aux->func_info; + func[i]->aux->func_info_cnt = prog->aux->func_info_cnt; + func[i]->aux->poke_tab = prog->aux->poke_tab; + func[i]->aux->size_poke_tab = prog->aux->size_poke_tab; + + for (j = 0; j < prog->aux->size_poke_tab; j++) { + struct bpf_jit_poke_descriptor *poke; + + poke = &prog->aux->poke_tab[j]; + if (poke->insn_idx < subprog_end && + poke->insn_idx >= subprog_start) + poke->aux = func[i]->aux; + } + + func[i]->aux->name[0] = 'F'; + func[i]->aux->stack_depth = env->subprog_info[i].stack_depth; + func[i]->jit_requested = 1; + func[i]->blinding_requested = prog->blinding_requested; + func[i]->aux->kfunc_tab = prog->aux->kfunc_tab; + func[i]->aux->kfunc_btf_tab = prog->aux->kfunc_btf_tab; + func[i]->aux->linfo = prog->aux->linfo; + func[i]->aux->nr_linfo = prog->aux->nr_linfo; + func[i]->aux->jited_linfo = prog->aux->jited_linfo; + func[i]->aux->linfo_idx = env->subprog_info[i].linfo_idx; + num_exentries = 0; + insn = func[i]->insnsi; + for (j = 0; j < func[i]->len; j++, insn++) { + if (BPF_CLASS(insn->code) == BPF_LDX && + (BPF_MODE(insn->code) == BPF_PROBE_MEM || + BPF_MODE(insn->code) == BPF_PROBE_MEMSX)) + num_exentries++; + } + func[i]->aux->num_exentries = num_exentries; + func[i]->aux->tail_call_reachable = env->subprog_info[i].tail_call_reachable; + func[i] = bpf_int_jit_compile(func[i]); + if (!func[i]->jited) { + err = -ENOTSUPP; + goto out_free; + } + cond_resched(); + } + + /* at this point all bpf functions were successfully JITed + * now populate all bpf_calls with correct addresses and + * run last pass of JIT + */ + for (i = 0; i < env->subprog_cnt; i++) { + insn = func[i]->insnsi; + for (j = 0; j < func[i]->len; j++, insn++) { + if (bpf_pseudo_func(insn)) { + subprog = insn->off; + insn[0].imm = (u32)(long)func[subprog]->bpf_func; + insn[1].imm = ((u64)(long)func[subprog]->bpf_func) >> 32; + continue; + } + if (!bpf_pseudo_call(insn)) + continue; + subprog = insn->off; + insn->imm = BPF_CALL_IMM(func[subprog]->bpf_func); + } + + /* we use the aux data to keep a list of the start addresses + * of the JITed images for each function in the program + * + * for some architectures, such as powerpc64, the imm field + * might not be large enough to hold the offset of the start + * address of the callee's JITed image from __bpf_call_base + * + * in such cases, we can lookup the start address of a callee + * by using its subprog id, available from the off field of + * the call instruction, as an index for this list + */ + func[i]->aux->func = func; + func[i]->aux->func_cnt = env->subprog_cnt; + } + for (i = 0; i < env->subprog_cnt; i++) { + old_bpf_func = func[i]->bpf_func; + tmp = bpf_int_jit_compile(func[i]); + if (tmp != func[i] || func[i]->bpf_func != old_bpf_func) { + verbose(env, "JIT doesn't support bpf-to-bpf calls\n"); + err = -ENOTSUPP; + goto out_free; + } + cond_resched(); + } + + /* finally lock prog and jit images for all functions and + * populate kallsysm. Begin at the first subprogram, since + * bpf_prog_load will add the kallsyms for the main program. + */ + for (i = 1; i < env->subprog_cnt; i++) { + bpf_prog_lock_ro(func[i]); + bpf_prog_kallsyms_add(func[i]); + } + + /* Last step: make now unused interpreter insns from main + * prog consistent for later dump requests, so they can + * later look the same as if they were interpreted only. + */ + for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) { + if (bpf_pseudo_func(insn)) { + insn[0].imm = env->insn_aux_data[i].call_imm; + insn[1].imm = insn->off; + insn->off = 0; + continue; + } + if (!bpf_pseudo_call(insn)) + continue; + insn->off = env->insn_aux_data[i].call_imm; + subprog = find_subprog(env, i + insn->off + 1); + insn->imm = subprog; + } + + prog->jited = 1; + prog->bpf_func = func[0]->bpf_func; + prog->jited_len = func[0]->jited_len; + prog->aux->extable = func[0]->aux->extable; + prog->aux->num_exentries = func[0]->aux->num_exentries; + prog->aux->func = func; + prog->aux->func_cnt = env->subprog_cnt; + bpf_prog_jit_attempt_done(prog); + return 0; +out_free: + /* We failed JIT'ing, so at this point we need to unregister poke + * descriptors from subprogs, so that kernel is not attempting to + * patch it anymore as we're freeing the subprog JIT memory. + */ + for (i = 0; i < prog->aux->size_poke_tab; i++) { + map_ptr = prog->aux->poke_tab[i].tail_call.map; + map_ptr->ops->map_poke_untrack(map_ptr, prog->aux); + } + /* At this point we're guaranteed that poke descriptors are not + * live anymore. We can just unlink its descriptor table as it's + * released with the main prog. + */ + for (i = 0; i < env->subprog_cnt; i++) { + if (!func[i]) + continue; + func[i]->aux->poke_tab = NULL; + bpf_jit_free(func[i]); + } + kfree(func); +out_undo_insn: + /* cleanup main prog to be interpreted */ + prog->jit_requested = 0; + prog->blinding_requested = 0; + for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) { + if (!bpf_pseudo_call(insn)) + continue; + insn->off = 0; + insn->imm = env->insn_aux_data[i].call_imm; + } + bpf_prog_jit_attempt_done(prog); + return err; +} + +static int fixup_call_args(struct bpf_verifier_env *env) +{ +#ifndef CONFIG_BPF_JIT_ALWAYS_ON + struct bpf_prog *prog = env->prog; + struct bpf_insn *insn = prog->insnsi; + bool has_kfunc_call = bpf_prog_has_kfunc_call(prog); + int i, depth; +#endif + int err = 0; + + if (env->prog->jit_requested && + !bpf_prog_is_offloaded(env->prog->aux)) { + err = jit_subprogs(env); + if (err == 0) + return 0; + if (err == -EFAULT) + return err; + } +#ifndef CONFIG_BPF_JIT_ALWAYS_ON + if (has_kfunc_call) { + verbose(env, "calling kernel functions are not allowed in non-JITed programs\n"); + return -EINVAL; + } + if (env->subprog_cnt > 1 && env->prog->aux->tail_call_reachable) { + /* When JIT fails the progs with bpf2bpf calls and tail_calls + * have to be rejected, since interpreter doesn't support them yet. + */ + verbose(env, "tail_calls are not allowed in non-JITed programs with bpf-to-bpf calls\n"); + return -EINVAL; + } + for (i = 0; i < prog->len; i++, insn++) { + if (bpf_pseudo_func(insn)) { + /* When JIT fails the progs with callback calls + * have to be rejected, since interpreter doesn't support them yet. + */ + verbose(env, "callbacks are not allowed in non-JITed programs\n"); + return -EINVAL; + } + + if (!bpf_pseudo_call(insn)) + continue; + depth = get_callee_stack_depth(env, insn, i); + if (depth < 0) + return depth; + bpf_patch_call_args(insn, depth); + } + err = 0; +#endif + return err; +} + +/* replace a generic kfunc with a specialized version if necessary */ +static void specialize_kfunc(struct bpf_verifier_env *env, + u32 func_id, u16 offset, unsigned long *addr) +{ + struct bpf_prog *prog = env->prog; + bool seen_direct_write; + void *xdp_kfunc; + bool is_rdonly; + + if (bpf_dev_bound_kfunc_id(func_id)) { + xdp_kfunc = bpf_dev_bound_resolve_kfunc(prog, func_id); + if (xdp_kfunc) { + *addr = (unsigned long)xdp_kfunc; + return; + } + /* fallback to default kfunc when not supported by netdev */ + } + + if (offset) + return; + + if (func_id == special_kfunc_list[KF_bpf_dynptr_from_skb]) { + seen_direct_write = env->seen_direct_write; + is_rdonly = !may_access_direct_pkt_data(env, NULL, BPF_WRITE); + + if (is_rdonly) + *addr = (unsigned long)bpf_dynptr_from_skb_rdonly; + + /* restore env->seen_direct_write to its original value, since + * may_access_direct_pkt_data mutates it + */ + env->seen_direct_write = seen_direct_write; + } +} + +static void __fixup_collection_insert_kfunc(struct bpf_insn_aux_data *insn_aux, + u16 struct_meta_reg, + u16 node_offset_reg, + struct bpf_insn *insn, + struct bpf_insn *insn_buf, + int *cnt) +{ + struct btf_struct_meta *kptr_struct_meta = insn_aux->kptr_struct_meta; + struct bpf_insn addr[2] = { BPF_LD_IMM64(struct_meta_reg, (long)kptr_struct_meta) }; + + insn_buf[0] = addr[0]; + insn_buf[1] = addr[1]; + insn_buf[2] = BPF_MOV64_IMM(node_offset_reg, insn_aux->insert_off); + insn_buf[3] = *insn; + *cnt = 4; +} + +static int fixup_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, + struct bpf_insn *insn_buf, int insn_idx, int *cnt) +{ + const struct bpf_kfunc_desc *desc; + + if (!insn->imm) { + verbose(env, "invalid kernel function call not eliminated in verifier pass\n"); + return -EINVAL; + } + + *cnt = 0; + + /* insn->imm has the btf func_id. Replace it with an offset relative to + * __bpf_call_base, unless the JIT needs to call functions that are + * further than 32 bits away (bpf_jit_supports_far_kfunc_call()). + */ + desc = find_kfunc_desc(env->prog, insn->imm, insn->off); + if (!desc) { + verbose(env, "verifier internal error: kernel function descriptor not found for func_id %u\n", + insn->imm); + return -EFAULT; + } + + if (!bpf_jit_supports_far_kfunc_call()) + insn->imm = BPF_CALL_IMM(desc->addr); + if (insn->off) + return 0; + if (desc->func_id == special_kfunc_list[KF_bpf_obj_new_impl]) { + struct btf_struct_meta *kptr_struct_meta = env->insn_aux_data[insn_idx].kptr_struct_meta; + struct bpf_insn addr[2] = { BPF_LD_IMM64(BPF_REG_2, (long)kptr_struct_meta) }; + u64 obj_new_size = env->insn_aux_data[insn_idx].obj_new_size; + + insn_buf[0] = BPF_MOV64_IMM(BPF_REG_1, obj_new_size); + insn_buf[1] = addr[0]; + insn_buf[2] = addr[1]; + insn_buf[3] = *insn; + *cnt = 4; + } else if (desc->func_id == special_kfunc_list[KF_bpf_obj_drop_impl] || + desc->func_id == special_kfunc_list[KF_bpf_refcount_acquire_impl]) { + struct btf_struct_meta *kptr_struct_meta = env->insn_aux_data[insn_idx].kptr_struct_meta; + struct bpf_insn addr[2] = { BPF_LD_IMM64(BPF_REG_2, (long)kptr_struct_meta) }; + + if (desc->func_id == special_kfunc_list[KF_bpf_refcount_acquire_impl] && + !kptr_struct_meta) { + verbose(env, "verifier internal error: kptr_struct_meta expected at insn_idx %d\n", + insn_idx); + return -EFAULT; + } + + insn_buf[0] = addr[0]; + insn_buf[1] = addr[1]; + insn_buf[2] = *insn; + *cnt = 3; + } else if (desc->func_id == special_kfunc_list[KF_bpf_list_push_back_impl] || + desc->func_id == special_kfunc_list[KF_bpf_list_push_front_impl] || + desc->func_id == special_kfunc_list[KF_bpf_rbtree_add_impl]) { + struct btf_struct_meta *kptr_struct_meta = env->insn_aux_data[insn_idx].kptr_struct_meta; + int struct_meta_reg = BPF_REG_3; + int node_offset_reg = BPF_REG_4; + + /* rbtree_add has extra 'less' arg, so args-to-fixup are in diff regs */ + if (desc->func_id == special_kfunc_list[KF_bpf_rbtree_add_impl]) { + struct_meta_reg = BPF_REG_4; + node_offset_reg = BPF_REG_5; + } + + if (!kptr_struct_meta) { + verbose(env, "verifier internal error: kptr_struct_meta expected at insn_idx %d\n", + insn_idx); + return -EFAULT; + } + + __fixup_collection_insert_kfunc(&env->insn_aux_data[insn_idx], struct_meta_reg, + node_offset_reg, insn, insn_buf, cnt); + } else if (desc->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx] || + desc->func_id == special_kfunc_list[KF_bpf_rdonly_cast]) { + insn_buf[0] = BPF_MOV64_REG(BPF_REG_0, BPF_REG_1); + *cnt = 1; + } + return 0; +} + +/* Do various post-verification rewrites in a single program pass. + * These rewrites simplify JIT and interpreter implementations. + */ +static int do_misc_fixups(struct bpf_verifier_env *env) +{ + struct bpf_prog *prog = env->prog; + enum bpf_attach_type eatype = prog->expected_attach_type; + enum bpf_prog_type prog_type = resolve_prog_type(prog); + struct bpf_insn *insn = prog->insnsi; + const struct bpf_func_proto *fn; + const int insn_cnt = prog->len; + const struct bpf_map_ops *ops; + struct bpf_insn_aux_data *aux; + struct bpf_insn insn_buf[16]; + struct bpf_prog *new_prog; + struct bpf_map *map_ptr; + int i, ret, cnt, delta = 0; + + for (i = 0; i < insn_cnt; i++, insn++) { + /* Make divide-by-zero exceptions impossible. */ + if (insn->code == (BPF_ALU64 | BPF_MOD | BPF_X) || + insn->code == (BPF_ALU64 | BPF_DIV | BPF_X) || + insn->code == (BPF_ALU | BPF_MOD | BPF_X) || + insn->code == (BPF_ALU | BPF_DIV | BPF_X)) { + bool is64 = BPF_CLASS(insn->code) == BPF_ALU64; + bool isdiv = BPF_OP(insn->code) == BPF_DIV; + struct bpf_insn *patchlet; + struct bpf_insn chk_and_div[] = { + /* [R,W]x div 0 -> 0 */ + BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) | + BPF_JNE | BPF_K, insn->src_reg, + 0, 2, 0), + BPF_ALU32_REG(BPF_XOR, insn->dst_reg, insn->dst_reg), + BPF_JMP_IMM(BPF_JA, 0, 0, 1), + *insn, + }; + struct bpf_insn chk_and_mod[] = { + /* [R,W]x mod 0 -> [R,W]x */ + BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) | + BPF_JEQ | BPF_K, insn->src_reg, + 0, 1 + (is64 ? 0 : 1), 0), + *insn, + BPF_JMP_IMM(BPF_JA, 0, 0, 1), + BPF_MOV32_REG(insn->dst_reg, insn->dst_reg), + }; + + patchlet = isdiv ? chk_and_div : chk_and_mod; + cnt = isdiv ? ARRAY_SIZE(chk_and_div) : + ARRAY_SIZE(chk_and_mod) - (is64 ? 2 : 0); + + new_prog = bpf_patch_insn_data(env, i + delta, patchlet, cnt); + if (!new_prog) + return -ENOMEM; + + delta += cnt - 1; + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + continue; + } + + /* Implement LD_ABS and LD_IND with a rewrite, if supported by the program type. */ + if (BPF_CLASS(insn->code) == BPF_LD && + (BPF_MODE(insn->code) == BPF_ABS || + BPF_MODE(insn->code) == BPF_IND)) { + cnt = env->ops->gen_ld_abs(insn, insn_buf); + if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) { + verbose(env, "bpf verifier is misconfigured\n"); + return -EINVAL; + } + + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); + if (!new_prog) + return -ENOMEM; + + delta += cnt - 1; + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + continue; + } + + /* Rewrite pointer arithmetic to mitigate speculation attacks. */ + if (insn->code == (BPF_ALU64 | BPF_ADD | BPF_X) || + insn->code == (BPF_ALU64 | BPF_SUB | BPF_X)) { + const u8 code_add = BPF_ALU64 | BPF_ADD | BPF_X; + const u8 code_sub = BPF_ALU64 | BPF_SUB | BPF_X; + struct bpf_insn *patch = &insn_buf[0]; + bool issrc, isneg, isimm; + u32 off_reg; + + aux = &env->insn_aux_data[i + delta]; + if (!aux->alu_state || + aux->alu_state == BPF_ALU_NON_POINTER) + continue; + + isneg = aux->alu_state & BPF_ALU_NEG_VALUE; + issrc = (aux->alu_state & BPF_ALU_SANITIZE) == + BPF_ALU_SANITIZE_SRC; + isimm = aux->alu_state & BPF_ALU_IMMEDIATE; + + off_reg = issrc ? insn->src_reg : insn->dst_reg; + if (isimm) { + *patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit); + } else { + if (isneg) + *patch++ = BPF_ALU64_IMM(BPF_MUL, off_reg, -1); + *patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit); + *patch++ = BPF_ALU64_REG(BPF_SUB, BPF_REG_AX, off_reg); + *patch++ = BPF_ALU64_REG(BPF_OR, BPF_REG_AX, off_reg); + *patch++ = BPF_ALU64_IMM(BPF_NEG, BPF_REG_AX, 0); + *patch++ = BPF_ALU64_IMM(BPF_ARSH, BPF_REG_AX, 63); + *patch++ = BPF_ALU64_REG(BPF_AND, BPF_REG_AX, off_reg); + } + if (!issrc) + *patch++ = BPF_MOV64_REG(insn->dst_reg, insn->src_reg); + insn->src_reg = BPF_REG_AX; + if (isneg) + insn->code = insn->code == code_add ? + code_sub : code_add; + *patch++ = *insn; + if (issrc && isneg && !isimm) + *patch++ = BPF_ALU64_IMM(BPF_MUL, off_reg, -1); + cnt = patch - insn_buf; + + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); + if (!new_prog) + return -ENOMEM; + + delta += cnt - 1; + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + continue; + } + + if (insn->code != (BPF_JMP | BPF_CALL)) + continue; + if (insn->src_reg == BPF_PSEUDO_CALL) + continue; + if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) { + ret = fixup_kfunc_call(env, insn, insn_buf, i + delta, &cnt); + if (ret) + return ret; + if (cnt == 0) + continue; + + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); + if (!new_prog) + return -ENOMEM; + + delta += cnt - 1; + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + continue; + } + + if (insn->imm == BPF_FUNC_get_route_realm) + prog->dst_needed = 1; + if (insn->imm == BPF_FUNC_get_prandom_u32) + bpf_user_rnd_init_once(); + if (insn->imm == BPF_FUNC_override_return) + prog->kprobe_override = 1; + if (insn->imm == BPF_FUNC_tail_call) { + /* If we tail call into other programs, we + * cannot make any assumptions since they can + * be replaced dynamically during runtime in + * the program array. + */ + prog->cb_access = 1; + if (!allow_tail_call_in_subprogs(env)) + prog->aux->stack_depth = MAX_BPF_STACK; + prog->aux->max_pkt_offset = MAX_PACKET_OFF; + + /* mark bpf_tail_call as different opcode to avoid + * conditional branch in the interpreter for every normal + * call and to prevent accidental JITing by JIT compiler + * that doesn't support bpf_tail_call yet + */ + insn->imm = 0; + insn->code = BPF_JMP | BPF_TAIL_CALL; + + aux = &env->insn_aux_data[i + delta]; + if (env->bpf_capable && !prog->blinding_requested && + prog->jit_requested && + !bpf_map_key_poisoned(aux) && + !bpf_map_ptr_poisoned(aux) && + !bpf_map_ptr_unpriv(aux)) { + struct bpf_jit_poke_descriptor desc = { + .reason = BPF_POKE_REASON_TAIL_CALL, + .tail_call.map = BPF_MAP_PTR(aux->map_ptr_state), + .tail_call.key = bpf_map_key_immediate(aux), + .insn_idx = i + delta, + }; + + ret = bpf_jit_add_poke_descriptor(prog, &desc); + if (ret < 0) { + verbose(env, "adding tail call poke descriptor failed\n"); + return ret; + } + + insn->imm = ret + 1; + continue; + } + + if (!bpf_map_ptr_unpriv(aux)) + continue; + + /* instead of changing every JIT dealing with tail_call + * emit two extra insns: + * if (index >= max_entries) goto out; + * index &= array->index_mask; + * to avoid out-of-bounds cpu speculation + */ + if (bpf_map_ptr_poisoned(aux)) { + verbose(env, "tail_call abusing map_ptr\n"); + return -EINVAL; + } + + map_ptr = BPF_MAP_PTR(aux->map_ptr_state); + insn_buf[0] = BPF_JMP_IMM(BPF_JGE, BPF_REG_3, + map_ptr->max_entries, 2); + insn_buf[1] = BPF_ALU32_IMM(BPF_AND, BPF_REG_3, + container_of(map_ptr, + struct bpf_array, + map)->index_mask); + insn_buf[2] = *insn; + cnt = 3; + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); + if (!new_prog) + return -ENOMEM; + + delta += cnt - 1; + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + continue; + } + + if (insn->imm == BPF_FUNC_timer_set_callback) { + /* The verifier will process callback_fn as many times as necessary + * with different maps and the register states prepared by + * set_timer_callback_state will be accurate. + * + * The following use case is valid: + * map1 is shared by prog1, prog2, prog3. + * prog1 calls bpf_timer_init for some map1 elements + * prog2 calls bpf_timer_set_callback for some map1 elements. + * Those that were not bpf_timer_init-ed will return -EINVAL. + * prog3 calls bpf_timer_start for some map1 elements. + * Those that were not both bpf_timer_init-ed and + * bpf_timer_set_callback-ed will return -EINVAL. + */ + struct bpf_insn ld_addrs[2] = { + BPF_LD_IMM64(BPF_REG_3, (long)prog->aux), + }; + + insn_buf[0] = ld_addrs[0]; + insn_buf[1] = ld_addrs[1]; + insn_buf[2] = *insn; + cnt = 3; + + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); + if (!new_prog) + return -ENOMEM; + + delta += cnt - 1; + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + goto patch_call_imm; + } + + if (is_storage_get_function(insn->imm)) { + if (!env->prog->aux->sleepable || + env->insn_aux_data[i + delta].storage_get_func_atomic) + insn_buf[0] = BPF_MOV64_IMM(BPF_REG_5, (__force __s32)GFP_ATOMIC); + else + insn_buf[0] = BPF_MOV64_IMM(BPF_REG_5, (__force __s32)GFP_KERNEL); + insn_buf[1] = *insn; + cnt = 2; + + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); + if (!new_prog) + return -ENOMEM; + + delta += cnt - 1; + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + goto patch_call_imm; + } + + /* BPF_EMIT_CALL() assumptions in some of the map_gen_lookup + * and other inlining handlers are currently limited to 64 bit + * only. + */ + if (prog->jit_requested && BITS_PER_LONG == 64 && + (insn->imm == BPF_FUNC_map_lookup_elem || + insn->imm == BPF_FUNC_map_update_elem || + insn->imm == BPF_FUNC_map_delete_elem || + insn->imm == BPF_FUNC_map_push_elem || + insn->imm == BPF_FUNC_map_pop_elem || + insn->imm == BPF_FUNC_map_peek_elem || + insn->imm == BPF_FUNC_redirect_map || + insn->imm == BPF_FUNC_for_each_map_elem || + insn->imm == BPF_FUNC_map_lookup_percpu_elem)) { + aux = &env->insn_aux_data[i + delta]; + if (bpf_map_ptr_poisoned(aux)) + goto patch_call_imm; + + map_ptr = BPF_MAP_PTR(aux->map_ptr_state); + ops = map_ptr->ops; + if (insn->imm == BPF_FUNC_map_lookup_elem && + ops->map_gen_lookup) { + cnt = ops->map_gen_lookup(map_ptr, insn_buf); + if (cnt == -EOPNOTSUPP) + goto patch_map_ops_generic; + if (cnt <= 0 || cnt >= ARRAY_SIZE(insn_buf)) { + verbose(env, "bpf verifier is misconfigured\n"); + return -EINVAL; + } + + new_prog = bpf_patch_insn_data(env, i + delta, + insn_buf, cnt); + if (!new_prog) + return -ENOMEM; + + delta += cnt - 1; + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + continue; + } + + BUILD_BUG_ON(!__same_type(ops->map_lookup_elem, + (void *(*)(struct bpf_map *map, void *key))NULL)); + BUILD_BUG_ON(!__same_type(ops->map_delete_elem, + (long (*)(struct bpf_map *map, void *key))NULL)); + BUILD_BUG_ON(!__same_type(ops->map_update_elem, + (long (*)(struct bpf_map *map, void *key, void *value, + u64 flags))NULL)); + BUILD_BUG_ON(!__same_type(ops->map_push_elem, + (long (*)(struct bpf_map *map, void *value, + u64 flags))NULL)); + BUILD_BUG_ON(!__same_type(ops->map_pop_elem, + (long (*)(struct bpf_map *map, void *value))NULL)); + BUILD_BUG_ON(!__same_type(ops->map_peek_elem, + (long (*)(struct bpf_map *map, void *value))NULL)); + BUILD_BUG_ON(!__same_type(ops->map_redirect, + (long (*)(struct bpf_map *map, u64 index, u64 flags))NULL)); + BUILD_BUG_ON(!__same_type(ops->map_for_each_callback, + (long (*)(struct bpf_map *map, + bpf_callback_t callback_fn, + void *callback_ctx, + u64 flags))NULL)); + BUILD_BUG_ON(!__same_type(ops->map_lookup_percpu_elem, + (void *(*)(struct bpf_map *map, void *key, u32 cpu))NULL)); + +patch_map_ops_generic: + switch (insn->imm) { + case BPF_FUNC_map_lookup_elem: + insn->imm = BPF_CALL_IMM(ops->map_lookup_elem); + continue; + case BPF_FUNC_map_update_elem: + insn->imm = BPF_CALL_IMM(ops->map_update_elem); + continue; + case BPF_FUNC_map_delete_elem: + insn->imm = BPF_CALL_IMM(ops->map_delete_elem); + continue; + case BPF_FUNC_map_push_elem: + insn->imm = BPF_CALL_IMM(ops->map_push_elem); + continue; + case BPF_FUNC_map_pop_elem: + insn->imm = BPF_CALL_IMM(ops->map_pop_elem); + continue; + case BPF_FUNC_map_peek_elem: + insn->imm = BPF_CALL_IMM(ops->map_peek_elem); + continue; + case BPF_FUNC_redirect_map: + insn->imm = BPF_CALL_IMM(ops->map_redirect); + continue; + case BPF_FUNC_for_each_map_elem: + insn->imm = BPF_CALL_IMM(ops->map_for_each_callback); + continue; + case BPF_FUNC_map_lookup_percpu_elem: + insn->imm = BPF_CALL_IMM(ops->map_lookup_percpu_elem); + continue; + } + + goto patch_call_imm; + } + + /* Implement bpf_jiffies64 inline. */ + if (prog->jit_requested && BITS_PER_LONG == 64 && + insn->imm == BPF_FUNC_jiffies64) { + struct bpf_insn ld_jiffies_addr[2] = { + BPF_LD_IMM64(BPF_REG_0, + (unsigned long)&jiffies), + }; + + insn_buf[0] = ld_jiffies_addr[0]; + insn_buf[1] = ld_jiffies_addr[1]; + insn_buf[2] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, + BPF_REG_0, 0); + cnt = 3; + + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, + cnt); + if (!new_prog) + return -ENOMEM; + + delta += cnt - 1; + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + continue; + } + + /* Implement bpf_get_func_arg inline. */ + if (prog_type == BPF_PROG_TYPE_TRACING && + insn->imm == BPF_FUNC_get_func_arg) { + /* Load nr_args from ctx - 8 */ + insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8); + insn_buf[1] = BPF_JMP32_REG(BPF_JGE, BPF_REG_2, BPF_REG_0, 6); + insn_buf[2] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_2, 3); + insn_buf[3] = BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_1); + insn_buf[4] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_2, 0); + insn_buf[5] = BPF_STX_MEM(BPF_DW, BPF_REG_3, BPF_REG_0, 0); + insn_buf[6] = BPF_MOV64_IMM(BPF_REG_0, 0); + insn_buf[7] = BPF_JMP_A(1); + insn_buf[8] = BPF_MOV64_IMM(BPF_REG_0, -EINVAL); + cnt = 9; + + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); + if (!new_prog) + return -ENOMEM; + + delta += cnt - 1; + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + continue; + } + + /* Implement bpf_get_func_ret inline. */ + if (prog_type == BPF_PROG_TYPE_TRACING && + insn->imm == BPF_FUNC_get_func_ret) { + if (eatype == BPF_TRACE_FEXIT || + eatype == BPF_MODIFY_RETURN) { + /* Load nr_args from ctx - 8 */ + insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8); + insn_buf[1] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_0, 3); + insn_buf[2] = BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_1); + insn_buf[3] = BPF_LDX_MEM(BPF_DW, BPF_REG_3, BPF_REG_0, 0); + insn_buf[4] = BPF_STX_MEM(BPF_DW, BPF_REG_2, BPF_REG_3, 0); + insn_buf[5] = BPF_MOV64_IMM(BPF_REG_0, 0); + cnt = 6; + } else { + insn_buf[0] = BPF_MOV64_IMM(BPF_REG_0, -EOPNOTSUPP); + cnt = 1; + } + + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); + if (!new_prog) + return -ENOMEM; + + delta += cnt - 1; + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + continue; + } + + /* Implement get_func_arg_cnt inline. */ + if (prog_type == BPF_PROG_TYPE_TRACING && + insn->imm == BPF_FUNC_get_func_arg_cnt) { + /* Load nr_args from ctx - 8 */ + insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8); + + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, 1); + if (!new_prog) + return -ENOMEM; + + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + continue; + } + + /* Implement bpf_get_func_ip inline. */ + if (prog_type == BPF_PROG_TYPE_TRACING && + insn->imm == BPF_FUNC_get_func_ip) { + /* Load IP address from ctx - 16 */ + insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -16); + + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, 1); + if (!new_prog) + return -ENOMEM; + + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + continue; + } + +patch_call_imm: + fn = env->ops->get_func_proto(insn->imm, env->prog); + /* all functions that have prototype and verifier allowed + * programs to call them, must be real in-kernel functions + */ + if (!fn->func) { + verbose(env, + "kernel subsystem misconfigured func %s#%d\n", + func_id_name(insn->imm), insn->imm); + return -EFAULT; + } + insn->imm = fn->func - __bpf_call_base; + } + + /* Since poke tab is now finalized, publish aux to tracker. */ + for (i = 0; i < prog->aux->size_poke_tab; i++) { + map_ptr = prog->aux->poke_tab[i].tail_call.map; + if (!map_ptr->ops->map_poke_track || + !map_ptr->ops->map_poke_untrack || + !map_ptr->ops->map_poke_run) { + verbose(env, "bpf verifier is misconfigured\n"); + return -EINVAL; + } + + ret = map_ptr->ops->map_poke_track(map_ptr, prog->aux); + if (ret < 0) { + verbose(env, "tracking tail call prog failed\n"); + return ret; + } + } + + sort_kfunc_descs_by_imm_off(env->prog); + + return 0; +} + +static struct bpf_prog *inline_bpf_loop(struct bpf_verifier_env *env, + int position, + s32 stack_base, + u32 callback_subprogno, + u32 *cnt) +{ + s32 r6_offset = stack_base + 0 * BPF_REG_SIZE; + s32 r7_offset = stack_base + 1 * BPF_REG_SIZE; + s32 r8_offset = stack_base + 2 * BPF_REG_SIZE; + int reg_loop_max = BPF_REG_6; + int reg_loop_cnt = BPF_REG_7; + int reg_loop_ctx = BPF_REG_8; + + struct bpf_prog *new_prog; + u32 callback_start; + u32 call_insn_offset; + s32 callback_offset; + + /* This represents an inlined version of bpf_iter.c:bpf_loop, + * be careful to modify this code in sync. + */ + struct bpf_insn insn_buf[] = { + /* Return error and jump to the end of the patch if + * expected number of iterations is too big. + */ + BPF_JMP_IMM(BPF_JLE, BPF_REG_1, BPF_MAX_LOOPS, 2), + BPF_MOV32_IMM(BPF_REG_0, -E2BIG), + BPF_JMP_IMM(BPF_JA, 0, 0, 16), + /* spill R6, R7, R8 to use these as loop vars */ + BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_6, r6_offset), + BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_7, r7_offset), + BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_8, r8_offset), + /* initialize loop vars */ + BPF_MOV64_REG(reg_loop_max, BPF_REG_1), + BPF_MOV32_IMM(reg_loop_cnt, 0), + BPF_MOV64_REG(reg_loop_ctx, BPF_REG_3), + /* loop header, + * if reg_loop_cnt >= reg_loop_max skip the loop body + */ + BPF_JMP_REG(BPF_JGE, reg_loop_cnt, reg_loop_max, 5), + /* callback call, + * correct callback offset would be set after patching + */ + BPF_MOV64_REG(BPF_REG_1, reg_loop_cnt), + BPF_MOV64_REG(BPF_REG_2, reg_loop_ctx), + BPF_CALL_REL(0), + /* increment loop counter */ + BPF_ALU64_IMM(BPF_ADD, reg_loop_cnt, 1), + /* jump to loop header if callback returned 0 */ + BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, -6), + /* return value of bpf_loop, + * set R0 to the number of iterations + */ + BPF_MOV64_REG(BPF_REG_0, reg_loop_cnt), + /* restore original values of R6, R7, R8 */ + BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_10, r6_offset), + BPF_LDX_MEM(BPF_DW, BPF_REG_7, BPF_REG_10, r7_offset), + BPF_LDX_MEM(BPF_DW, BPF_REG_8, BPF_REG_10, r8_offset), + }; + + *cnt = ARRAY_SIZE(insn_buf); + new_prog = bpf_patch_insn_data(env, position, insn_buf, *cnt); + if (!new_prog) + return new_prog; + + /* callback start is known only after patching */ + callback_start = env->subprog_info[callback_subprogno].start; + /* Note: insn_buf[12] is an offset of BPF_CALL_REL instruction */ + call_insn_offset = position + 12; + callback_offset = callback_start - call_insn_offset - 1; + new_prog->insnsi[call_insn_offset].imm = callback_offset; + + return new_prog; +} + +static bool is_bpf_loop_call(struct bpf_insn *insn) +{ + return insn->code == (BPF_JMP | BPF_CALL) && + insn->src_reg == 0 && + insn->imm == BPF_FUNC_loop; +} + +/* For all sub-programs in the program (including main) check + * insn_aux_data to see if there are bpf_loop calls that require + * inlining. If such calls are found the calls are replaced with a + * sequence of instructions produced by `inline_bpf_loop` function and + * subprog stack_depth is increased by the size of 3 registers. + * This stack space is used to spill values of the R6, R7, R8. These + * registers are used to store the loop bound, counter and context + * variables. + */ +static int optimize_bpf_loop(struct bpf_verifier_env *env) +{ + struct bpf_subprog_info *subprogs = env->subprog_info; + int i, cur_subprog = 0, cnt, delta = 0; + struct bpf_insn *insn = env->prog->insnsi; + int insn_cnt = env->prog->len; + u16 stack_depth = subprogs[cur_subprog].stack_depth; + u16 stack_depth_roundup = round_up(stack_depth, 8) - stack_depth; + u16 stack_depth_extra = 0; + + for (i = 0; i < insn_cnt; i++, insn++) { + struct bpf_loop_inline_state *inline_state = + &env->insn_aux_data[i + delta].loop_inline_state; + + if (is_bpf_loop_call(insn) && inline_state->fit_for_inline) { + struct bpf_prog *new_prog; + + stack_depth_extra = BPF_REG_SIZE * 3 + stack_depth_roundup; + new_prog = inline_bpf_loop(env, + i + delta, + -(stack_depth + stack_depth_extra), + inline_state->callback_subprogno, + &cnt); + if (!new_prog) + return -ENOMEM; + + delta += cnt - 1; + env->prog = new_prog; + insn = new_prog->insnsi + i + delta; + } + + if (subprogs[cur_subprog + 1].start == i + delta + 1) { + subprogs[cur_subprog].stack_depth += stack_depth_extra; + cur_subprog++; + stack_depth = subprogs[cur_subprog].stack_depth; + stack_depth_roundup = round_up(stack_depth, 8) - stack_depth; + stack_depth_extra = 0; + } + } + + env->prog->aux->stack_depth = env->subprog_info[0].stack_depth; + + return 0; +} + +static void free_states(struct bpf_verifier_env *env) +{ + struct bpf_verifier_state_list *sl, *sln; + int i; + + sl = env->free_list; + while (sl) { + sln = sl->next; + free_verifier_state(&sl->state, false); + kfree(sl); + sl = sln; + } + env->free_list = NULL; + + if (!env->explored_states) + return; + + for (i = 0; i < state_htab_size(env); i++) { + sl = env->explored_states[i]; + + while (sl) { + sln = sl->next; + free_verifier_state(&sl->state, false); + kfree(sl); + sl = sln; + } + env->explored_states[i] = NULL; + } +} + +static int do_check_common(struct bpf_verifier_env *env, int subprog) +{ + bool pop_log = !(env->log.level & BPF_LOG_LEVEL2); + struct bpf_verifier_state *state; + struct bpf_reg_state *regs; + int ret, i; + + env->prev_linfo = NULL; + env->pass_cnt++; + + state = kzalloc(sizeof(struct bpf_verifier_state), GFP_KERNEL); + if (!state) + return -ENOMEM; + state->curframe = 0; + state->speculative = false; + state->branches = 1; + state->frame[0] = kzalloc(sizeof(struct bpf_func_state), GFP_KERNEL); + if (!state->frame[0]) { + kfree(state); + return -ENOMEM; + } + env->cur_state = state; + init_func_state(env, state->frame[0], + BPF_MAIN_FUNC /* callsite */, + 0 /* frameno */, + subprog); + state->first_insn_idx = env->subprog_info[subprog].start; + state->last_insn_idx = -1; + + regs = state->frame[state->curframe]->regs; + if (subprog || env->prog->type == BPF_PROG_TYPE_EXT) { + ret = btf_prepare_func_args(env, subprog, regs); + if (ret) + goto out; + for (i = BPF_REG_1; i <= BPF_REG_5; i++) { + if (regs[i].type == PTR_TO_CTX) + mark_reg_known_zero(env, regs, i); + else if (regs[i].type == SCALAR_VALUE) + mark_reg_unknown(env, regs, i); + else if (base_type(regs[i].type) == PTR_TO_MEM) { + const u32 mem_size = regs[i].mem_size; + + mark_reg_known_zero(env, regs, i); + regs[i].mem_size = mem_size; + regs[i].id = ++env->id_gen; + } + } + } else { + /* 1st arg to a function */ + regs[BPF_REG_1].type = PTR_TO_CTX; + mark_reg_known_zero(env, regs, BPF_REG_1); + ret = btf_check_subprog_arg_match(env, subprog, regs); + if (ret == -EFAULT) + /* unlikely verifier bug. abort. + * ret == 0 and ret < 0 are sadly acceptable for + * main() function due to backward compatibility. + * Like socket filter program may be written as: + * int bpf_prog(struct pt_regs *ctx) + * and never dereference that ctx in the program. + * 'struct pt_regs' is a type mismatch for socket + * filter that should be using 'struct __sk_buff'. + */ + goto out; + } + + ret = do_check(env); +out: + /* check for NULL is necessary, since cur_state can be freed inside + * do_check() under memory pressure. + */ + if (env->cur_state) { + free_verifier_state(env->cur_state, true); + env->cur_state = NULL; + } + while (!pop_stack(env, NULL, NULL, false)); + if (!ret && pop_log) + bpf_vlog_reset(&env->log, 0); + free_states(env); + return ret; +} + +/* Verify all global functions in a BPF program one by one based on their BTF. + * All global functions must pass verification. Otherwise the whole program is rejected. + * Consider: + * int bar(int); + * int foo(int f) + * { + * return bar(f); + * } + * int bar(int b) + * { + * ... + * } + * foo() will be verified first for R1=any_scalar_value. During verification it + * will be assumed that bar() already verified successfully and call to bar() + * from foo() will be checked for type match only. Later bar() will be verified + * independently to check that it's safe for R1=any_scalar_value. + */ +static int do_check_subprogs(struct bpf_verifier_env *env) +{ + struct bpf_prog_aux *aux = env->prog->aux; + int i, ret; + + if (!aux->func_info) + return 0; + + for (i = 1; i < env->subprog_cnt; i++) { + if (aux->func_info_aux[i].linkage != BTF_FUNC_GLOBAL) + continue; + env->insn_idx = env->subprog_info[i].start; + WARN_ON_ONCE(env->insn_idx == 0); + ret = do_check_common(env, i); + if (ret) { + return ret; + } else if (env->log.level & BPF_LOG_LEVEL) { + verbose(env, + "Func#%d is safe for any args that match its prototype\n", + i); + } + } + return 0; +} + +static int do_check_main(struct bpf_verifier_env *env) +{ + int ret; + + env->insn_idx = 0; + ret = do_check_common(env, 0); + if (!ret) + env->prog->aux->stack_depth = env->subprog_info[0].stack_depth; + return ret; +} + + +static void print_verification_stats(struct bpf_verifier_env *env) +{ + int i; + + if (env->log.level & BPF_LOG_STATS) { + verbose(env, "verification time %lld usec\n", + div_u64(env->verification_time, 1000)); + verbose(env, "stack depth "); + for (i = 0; i < env->subprog_cnt; i++) { + u32 depth = env->subprog_info[i].stack_depth; + + verbose(env, "%d", depth); + if (i + 1 < env->subprog_cnt) + verbose(env, "+"); + } + verbose(env, "\n"); + } + verbose(env, "processed %d insns (limit %d) max_states_per_insn %d " + "total_states %d peak_states %d mark_read %d\n", + env->insn_processed, BPF_COMPLEXITY_LIMIT_INSNS, + env->max_states_per_insn, env->total_states, + env->peak_states, env->longest_mark_read_walk); +} + +static int check_struct_ops_btf_id(struct bpf_verifier_env *env) +{ + const struct btf_type *t, *func_proto; + const struct bpf_struct_ops *st_ops; + const struct btf_member *member; + struct bpf_prog *prog = env->prog; + u32 btf_id, member_idx; + const char *mname; + + if (!prog->gpl_compatible) { + verbose(env, "struct ops programs must have a GPL compatible license\n"); + return -EINVAL; + } + + btf_id = prog->aux->attach_btf_id; + st_ops = bpf_struct_ops_find(btf_id); + if (!st_ops) { + verbose(env, "attach_btf_id %u is not a supported struct\n", + btf_id); + return -ENOTSUPP; + } + + t = st_ops->type; + member_idx = prog->expected_attach_type; + if (member_idx >= btf_type_vlen(t)) { + verbose(env, "attach to invalid member idx %u of struct %s\n", + member_idx, st_ops->name); + return -EINVAL; + } + + member = &btf_type_member(t)[member_idx]; + mname = btf_name_by_offset(btf_vmlinux, member->name_off); + func_proto = btf_type_resolve_func_ptr(btf_vmlinux, member->type, + NULL); + if (!func_proto) { + verbose(env, "attach to invalid member %s(@idx %u) of struct %s\n", + mname, member_idx, st_ops->name); + return -EINVAL; + } + + if (st_ops->check_member) { + int err = st_ops->check_member(t, member, prog); + + if (err) { + verbose(env, "attach to unsupported member %s of struct %s\n", + mname, st_ops->name); + return err; + } + } + + prog->aux->attach_func_proto = func_proto; + prog->aux->attach_func_name = mname; + env->ops = st_ops->verifier_ops; + + return 0; +} +#define SECURITY_PREFIX "security_" + +static int check_attach_modify_return(unsigned long addr, const char *func_name) +{ + if (within_error_injection_list(addr) || + !strncmp(SECURITY_PREFIX, func_name, sizeof(SECURITY_PREFIX) - 1)) + return 0; + + return -EINVAL; +} + +/* list of non-sleepable functions that are otherwise on + * ALLOW_ERROR_INJECTION list + */ +BTF_SET_START(btf_non_sleepable_error_inject) +/* Three functions below can be called from sleepable and non-sleepable context. + * Assume non-sleepable from bpf safety point of view. + */ +BTF_ID(func, __filemap_add_folio) +BTF_ID(func, should_fail_alloc_page) +BTF_ID(func, should_failslab) +BTF_SET_END(btf_non_sleepable_error_inject) + +static int check_non_sleepable_error_inject(u32 btf_id) +{ + return btf_id_set_contains(&btf_non_sleepable_error_inject, btf_id); +} + +int bpf_check_attach_target(struct bpf_verifier_log *log, + const struct bpf_prog *prog, + const struct bpf_prog *tgt_prog, + u32 btf_id, + struct bpf_attach_target_info *tgt_info) +{ + bool prog_extension = prog->type == BPF_PROG_TYPE_EXT; + const char prefix[] = "btf_trace_"; + int ret = 0, subprog = -1, i; + const struct btf_type *t; + bool conservative = true; + const char *tname; + struct btf *btf; + long addr = 0; + struct module *mod = NULL; + + if (!btf_id) { + bpf_log(log, "Tracing programs must provide btf_id\n"); + return -EINVAL; + } + btf = tgt_prog ? tgt_prog->aux->btf : prog->aux->attach_btf; + if (!btf) { + bpf_log(log, + "FENTRY/FEXIT program can only be attached to another program annotated with BTF\n"); + return -EINVAL; + } + t = btf_type_by_id(btf, btf_id); + if (!t) { + bpf_log(log, "attach_btf_id %u is invalid\n", btf_id); + return -EINVAL; + } + tname = btf_name_by_offset(btf, t->name_off); + if (!tname) { + bpf_log(log, "attach_btf_id %u doesn't have a name\n", btf_id); + return -EINVAL; + } + if (tgt_prog) { + struct bpf_prog_aux *aux = tgt_prog->aux; + + if (bpf_prog_is_dev_bound(prog->aux) && + !bpf_prog_dev_bound_match(prog, tgt_prog)) { + bpf_log(log, "Target program bound device mismatch"); + return -EINVAL; + } + + for (i = 0; i < aux->func_info_cnt; i++) + if (aux->func_info[i].type_id == btf_id) { + subprog = i; + break; + } + if (subprog == -1) { + bpf_log(log, "Subprog %s doesn't exist\n", tname); + return -EINVAL; + } + conservative = aux->func_info_aux[subprog].unreliable; + if (prog_extension) { + if (conservative) { + bpf_log(log, + "Cannot replace static functions\n"); + return -EINVAL; + } + if (!prog->jit_requested) { + bpf_log(log, + "Extension programs should be JITed\n"); + return -EINVAL; + } + } + if (!tgt_prog->jited) { + bpf_log(log, "Can attach to only JITed progs\n"); + return -EINVAL; + } + if (tgt_prog->type == prog->type) { + /* Cannot fentry/fexit another fentry/fexit program. + * Cannot attach program extension to another extension. + * It's ok to attach fentry/fexit to extension program. + */ + bpf_log(log, "Cannot recursively attach\n"); + return -EINVAL; + } + if (tgt_prog->type == BPF_PROG_TYPE_TRACING && + prog_extension && + (tgt_prog->expected_attach_type == BPF_TRACE_FENTRY || + tgt_prog->expected_attach_type == BPF_TRACE_FEXIT)) { + /* Program extensions can extend all program types + * except fentry/fexit. The reason is the following. + * The fentry/fexit programs are used for performance + * analysis, stats and can be attached to any program + * type except themselves. When extension program is + * replacing XDP function it is necessary to allow + * performance analysis of all functions. Both original + * XDP program and its program extension. Hence + * attaching fentry/fexit to BPF_PROG_TYPE_EXT is + * allowed. If extending of fentry/fexit was allowed it + * would be possible to create long call chain + * fentry->extension->fentry->extension beyond + * reasonable stack size. Hence extending fentry is not + * allowed. + */ + bpf_log(log, "Cannot extend fentry/fexit\n"); + return -EINVAL; + } + } else { + if (prog_extension) { + bpf_log(log, "Cannot replace kernel functions\n"); + return -EINVAL; + } + } + + switch (prog->expected_attach_type) { + case BPF_TRACE_RAW_TP: + if (tgt_prog) { + bpf_log(log, + "Only FENTRY/FEXIT progs are attachable to another BPF prog\n"); + return -EINVAL; + } + if (!btf_type_is_typedef(t)) { + bpf_log(log, "attach_btf_id %u is not a typedef\n", + btf_id); + return -EINVAL; + } + if (strncmp(prefix, tname, sizeof(prefix) - 1)) { + bpf_log(log, "attach_btf_id %u points to wrong type name %s\n", + btf_id, tname); + return -EINVAL; + } + tname += sizeof(prefix) - 1; + t = btf_type_by_id(btf, t->type); + if (!btf_type_is_ptr(t)) + /* should never happen in valid vmlinux build */ + return -EINVAL; + t = btf_type_by_id(btf, t->type); + if (!btf_type_is_func_proto(t)) + /* should never happen in valid vmlinux build */ + return -EINVAL; + + break; + case BPF_TRACE_ITER: + if (!btf_type_is_func(t)) { + bpf_log(log, "attach_btf_id %u is not a function\n", + btf_id); + return -EINVAL; + } + t = btf_type_by_id(btf, t->type); + if (!btf_type_is_func_proto(t)) + return -EINVAL; + ret = btf_distill_func_proto(log, btf, t, tname, &tgt_info->fmodel); + if (ret) + return ret; + break; + default: + if (!prog_extension) + return -EINVAL; + fallthrough; + case BPF_MODIFY_RETURN: + case BPF_LSM_MAC: + case BPF_LSM_CGROUP: + case BPF_TRACE_FENTRY: + case BPF_TRACE_FEXIT: + if (!btf_type_is_func(t)) { + bpf_log(log, "attach_btf_id %u is not a function\n", + btf_id); + return -EINVAL; + } + if (prog_extension && + btf_check_type_match(log, prog, btf, t)) + return -EINVAL; + t = btf_type_by_id(btf, t->type); + if (!btf_type_is_func_proto(t)) + return -EINVAL; + + if ((prog->aux->saved_dst_prog_type || prog->aux->saved_dst_attach_type) && + (!tgt_prog || prog->aux->saved_dst_prog_type != tgt_prog->type || + prog->aux->saved_dst_attach_type != tgt_prog->expected_attach_type)) + return -EINVAL; + + if (tgt_prog && conservative) + t = NULL; + + ret = btf_distill_func_proto(log, btf, t, tname, &tgt_info->fmodel); + if (ret < 0) + return ret; + + if (tgt_prog) { + if (subprog == 0) + addr = (long) tgt_prog->bpf_func; + else + addr = (long) tgt_prog->aux->func[subprog]->bpf_func; + } else { + if (btf_is_module(btf)) { + mod = btf_try_get_module(btf); + if (mod) + addr = find_kallsyms_symbol_value(mod, tname); + else + addr = 0; + } else { + addr = kallsyms_lookup_name(tname); + } + if (!addr) { + module_put(mod); + bpf_log(log, + "The address of function %s cannot be found\n", + tname); + return -ENOENT; + } + } + + if (prog->aux->sleepable) { + ret = -EINVAL; + switch (prog->type) { + case BPF_PROG_TYPE_TRACING: + + /* fentry/fexit/fmod_ret progs can be sleepable if they are + * attached to ALLOW_ERROR_INJECTION and are not in denylist. + */ + if (!check_non_sleepable_error_inject(btf_id) && + within_error_injection_list(addr)) + ret = 0; + /* fentry/fexit/fmod_ret progs can also be sleepable if they are + * in the fmodret id set with the KF_SLEEPABLE flag. + */ + else { + u32 *flags = btf_kfunc_is_modify_return(btf, btf_id, + prog); + + if (flags && (*flags & KF_SLEEPABLE)) + ret = 0; + } + break; + case BPF_PROG_TYPE_LSM: + /* LSM progs check that they are attached to bpf_lsm_*() funcs. + * Only some of them are sleepable. + */ + if (bpf_lsm_is_sleepable_hook(btf_id)) + ret = 0; + break; + default: + break; + } + if (ret) { + module_put(mod); + bpf_log(log, "%s is not sleepable\n", tname); + return ret; + } + } else if (prog->expected_attach_type == BPF_MODIFY_RETURN) { + if (tgt_prog) { + module_put(mod); + bpf_log(log, "can't modify return codes of BPF programs\n"); + return -EINVAL; + } + ret = -EINVAL; + if (btf_kfunc_is_modify_return(btf, btf_id, prog) || + !check_attach_modify_return(addr, tname)) + ret = 0; + if (ret) { + module_put(mod); + bpf_log(log, "%s() is not modifiable\n", tname); + return ret; + } + } + + break; + } + tgt_info->tgt_addr = addr; + tgt_info->tgt_name = tname; + tgt_info->tgt_type = t; + tgt_info->tgt_mod = mod; + return 0; +} + +BTF_SET_START(btf_id_deny) +BTF_ID_UNUSED +#ifdef CONFIG_SMP +BTF_ID(func, migrate_disable) +BTF_ID(func, migrate_enable) +#endif +#if !defined CONFIG_PREEMPT_RCU && !defined CONFIG_TINY_RCU +BTF_ID(func, rcu_read_unlock_strict) +#endif +#if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_TRACE_PREEMPT_TOGGLE) +BTF_ID(func, preempt_count_add) +BTF_ID(func, preempt_count_sub) +#endif +#ifdef CONFIG_PREEMPT_RCU +BTF_ID(func, __rcu_read_lock) +BTF_ID(func, __rcu_read_unlock) +#endif +BTF_SET_END(btf_id_deny) + +static bool can_be_sleepable(struct bpf_prog *prog) +{ + if (prog->type == BPF_PROG_TYPE_TRACING) { + switch (prog->expected_attach_type) { + case BPF_TRACE_FENTRY: + case BPF_TRACE_FEXIT: + case BPF_MODIFY_RETURN: + case BPF_TRACE_ITER: + return true; + default: + return false; + } + } + return prog->type == BPF_PROG_TYPE_LSM || + prog->type == BPF_PROG_TYPE_KPROBE /* only for uprobes */ || + prog->type == BPF_PROG_TYPE_STRUCT_OPS; +} + +static int check_attach_btf_id(struct bpf_verifier_env *env) +{ + struct bpf_prog *prog = env->prog; + struct bpf_prog *tgt_prog = prog->aux->dst_prog; + struct bpf_attach_target_info tgt_info = {}; + u32 btf_id = prog->aux->attach_btf_id; + struct bpf_trampoline *tr; + int ret; + u64 key; + + if (prog->type == BPF_PROG_TYPE_SYSCALL) { + if (prog->aux->sleepable) + /* attach_btf_id checked to be zero already */ + return 0; + verbose(env, "Syscall programs can only be sleepable\n"); + return -EINVAL; + } + + if (prog->aux->sleepable && !can_be_sleepable(prog)) { + verbose(env, "Only fentry/fexit/fmod_ret, lsm, iter, uprobe, and struct_ops programs can be sleepable\n"); + return -EINVAL; + } + + if (prog->type == BPF_PROG_TYPE_STRUCT_OPS) + return check_struct_ops_btf_id(env); + + if (prog->type != BPF_PROG_TYPE_TRACING && + prog->type != BPF_PROG_TYPE_LSM && + prog->type != BPF_PROG_TYPE_EXT) + return 0; + + ret = bpf_check_attach_target(&env->log, prog, tgt_prog, btf_id, &tgt_info); + if (ret) + return ret; + + if (tgt_prog && prog->type == BPF_PROG_TYPE_EXT) { + /* to make freplace equivalent to their targets, they need to + * inherit env->ops and expected_attach_type for the rest of the + * verification + */ + env->ops = bpf_verifier_ops[tgt_prog->type]; + prog->expected_attach_type = tgt_prog->expected_attach_type; + } + + /* store info about the attachment target that will be used later */ + prog->aux->attach_func_proto = tgt_info.tgt_type; + prog->aux->attach_func_name = tgt_info.tgt_name; + prog->aux->mod = tgt_info.tgt_mod; + + if (tgt_prog) { + prog->aux->saved_dst_prog_type = tgt_prog->type; + prog->aux->saved_dst_attach_type = tgt_prog->expected_attach_type; + } + + if (prog->expected_attach_type == BPF_TRACE_RAW_TP) { + prog->aux->attach_btf_trace = true; + return 0; + } else if (prog->expected_attach_type == BPF_TRACE_ITER) { + if (!bpf_iter_prog_supported(prog)) + return -EINVAL; + return 0; + } + + if (prog->type == BPF_PROG_TYPE_LSM) { + ret = bpf_lsm_verify_prog(&env->log, prog); + if (ret < 0) + return ret; + } else if (prog->type == BPF_PROG_TYPE_TRACING && + btf_id_set_contains(&btf_id_deny, btf_id)) { + return -EINVAL; + } + + key = bpf_trampoline_compute_key(tgt_prog, prog->aux->attach_btf, btf_id); + tr = bpf_trampoline_get(key, &tgt_info); + if (!tr) + return -ENOMEM; + + if (tgt_prog && tgt_prog->aux->tail_call_reachable) + tr->flags = BPF_TRAMP_F_TAIL_CALL_CTX; + + prog->aux->dst_trampoline = tr; + return 0; +} + +struct btf *bpf_get_btf_vmlinux(void) +{ + if (!btf_vmlinux && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) { + mutex_lock(&bpf_verifier_lock); + if (!btf_vmlinux) + btf_vmlinux = btf_parse_vmlinux(); + mutex_unlock(&bpf_verifier_lock); + } + return btf_vmlinux; +} + +int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, __u32 uattr_size) +{ + u64 start_time = ktime_get_ns(); + struct bpf_verifier_env *env; + int i, len, ret = -EINVAL, err; + u32 log_true_size; + bool is_priv; + + /* no program is valid */ + if (ARRAY_SIZE(bpf_verifier_ops) == 0) + return -EINVAL; + + /* 'struct bpf_verifier_env' can be global, but since it's not small, + * allocate/free it every time bpf_check() is called + */ + env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL); + if (!env) + return -ENOMEM; + + env->bt.env = env; + + len = (*prog)->len; + env->insn_aux_data = + vzalloc(array_size(sizeof(struct bpf_insn_aux_data), len)); + ret = -ENOMEM; + if (!env->insn_aux_data) + goto err_free_env; + for (i = 0; i < len; i++) + env->insn_aux_data[i].orig_idx = i; + env->prog = *prog; + env->ops = bpf_verifier_ops[env->prog->type]; + env->fd_array = make_bpfptr(attr->fd_array, uattr.is_kernel); + is_priv = bpf_capable(); + + bpf_get_btf_vmlinux(); + + /* grab the mutex to protect few globals used by verifier */ + if (!is_priv) + mutex_lock(&bpf_verifier_lock); + + /* user could have requested verbose verifier output + * and supplied buffer to store the verification trace + */ + ret = bpf_vlog_init(&env->log, attr->log_level, + (char __user *) (unsigned long) attr->log_buf, + attr->log_size); + if (ret) + goto err_unlock; + + mark_verifier_state_clean(env); + + if (IS_ERR(btf_vmlinux)) { + /* Either gcc or pahole or kernel are broken. */ + verbose(env, "in-kernel BTF is malformed\n"); + ret = PTR_ERR(btf_vmlinux); + goto skip_full_check; + } + + env->strict_alignment = !!(attr->prog_flags & BPF_F_STRICT_ALIGNMENT); + if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) + env->strict_alignment = true; + if (attr->prog_flags & BPF_F_ANY_ALIGNMENT) + env->strict_alignment = false; + + env->allow_ptr_leaks = bpf_allow_ptr_leaks(); + env->allow_uninit_stack = bpf_allow_uninit_stack(); + env->bypass_spec_v1 = bpf_bypass_spec_v1(); + env->bypass_spec_v4 = bpf_bypass_spec_v4(); + env->bpf_capable = bpf_capable(); + + if (is_priv) + env->test_state_freq = attr->prog_flags & BPF_F_TEST_STATE_FREQ; + + env->explored_states = kvcalloc(state_htab_size(env), + sizeof(struct bpf_verifier_state_list *), + GFP_USER); + ret = -ENOMEM; + if (!env->explored_states) + goto skip_full_check; + + ret = add_subprog_and_kfunc(env); + if (ret < 0) + goto skip_full_check; + + ret = check_subprogs(env); + if (ret < 0) + goto skip_full_check; + + ret = check_btf_info(env, attr, uattr); + if (ret < 0) + goto skip_full_check; + + ret = check_attach_btf_id(env); + if (ret) + goto skip_full_check; + + ret = resolve_pseudo_ldimm64(env); + if (ret < 0) + goto skip_full_check; + + if (bpf_prog_is_offloaded(env->prog->aux)) { + ret = bpf_prog_offload_verifier_prep(env->prog); + if (ret) + goto skip_full_check; + } + + ret = check_cfg(env); + if (ret < 0) + goto skip_full_check; + + ret = do_check_subprogs(env); + ret = ret ?: do_check_main(env); + + if (ret == 0 && bpf_prog_is_offloaded(env->prog->aux)) + ret = bpf_prog_offload_finalize(env); + +skip_full_check: + kvfree(env->explored_states); + + if (ret == 0) + ret = check_max_stack_depth(env); + + /* instruction rewrites happen after this point */ + if (ret == 0) + ret = optimize_bpf_loop(env); + + if (is_priv) { + if (ret == 0) + opt_hard_wire_dead_code_branches(env); + if (ret == 0) + ret = opt_remove_dead_code(env); + if (ret == 0) + ret = opt_remove_nops(env); + } else { + if (ret == 0) + sanitize_dead_code(env); + } + + if (ret == 0) + /* program is valid, convert *(u32*)(ctx + off) accesses */ + ret = convert_ctx_accesses(env); + + if (ret == 0) + ret = do_misc_fixups(env); + + /* do 32-bit optimization after insn patching has done so those patched + * insns could be handled correctly. + */ + if (ret == 0 && !bpf_prog_is_offloaded(env->prog->aux)) { + ret = opt_subreg_zext_lo32_rnd_hi32(env, attr); + env->prog->aux->verifier_zext = bpf_jit_needs_zext() ? !ret + : false; + } + + if (ret == 0) + ret = fixup_call_args(env); + + env->verification_time = ktime_get_ns() - start_time; + print_verification_stats(env); + env->prog->aux->verified_insns = env->insn_processed; + + /* preserve original error even if log finalization is successful */ + err = bpf_vlog_finalize(&env->log, &log_true_size); + if (err) + ret = err; + + if (uattr_size >= offsetofend(union bpf_attr, log_true_size) && + copy_to_bpfptr_offset(uattr, offsetof(union bpf_attr, log_true_size), + &log_true_size, sizeof(log_true_size))) { + ret = -EFAULT; + goto err_release_maps; + } + + if (ret) + goto err_release_maps; + + if (env->used_map_cnt) { + /* if program passed verifier, update used_maps in bpf_prog_info */ + env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt, + sizeof(env->used_maps[0]), + GFP_KERNEL); + + if (!env->prog->aux->used_maps) { + ret = -ENOMEM; + goto err_release_maps; + } + + memcpy(env->prog->aux->used_maps, env->used_maps, + sizeof(env->used_maps[0]) * env->used_map_cnt); + env->prog->aux->used_map_cnt = env->used_map_cnt; + } + if (env->used_btf_cnt) { + /* if program passed verifier, update used_btfs in bpf_prog_aux */ + env->prog->aux->used_btfs = kmalloc_array(env->used_btf_cnt, + sizeof(env->used_btfs[0]), + GFP_KERNEL); + if (!env->prog->aux->used_btfs) { + ret = -ENOMEM; + goto err_release_maps; + } + + memcpy(env->prog->aux->used_btfs, env->used_btfs, + sizeof(env->used_btfs[0]) * env->used_btf_cnt); + env->prog->aux->used_btf_cnt = env->used_btf_cnt; + } + if (env->used_map_cnt || env->used_btf_cnt) { + /* program is valid. Convert pseudo bpf_ld_imm64 into generic + * bpf_ld_imm64 instructions + */ + convert_pseudo_ld_imm64(env); + } + + adjust_btf_func(env); + +err_release_maps: + if (!env->prog->aux->used_maps) + /* if we didn't copy map pointers into bpf_prog_info, release + * them now. Otherwise free_used_maps() will release them. + */ + release_maps(env); + if (!env->prog->aux->used_btfs) + release_btfs(env); + + /* extension progs temporarily inherit the attach_type of their targets + for verification purposes, so set it back to zero before returning + */ + if (env->prog->type == BPF_PROG_TYPE_EXT) + env->prog->expected_attach_type = 0; + + *prog = env->prog; +err_unlock: + if (!is_priv) + mutex_unlock(&bpf_verifier_lock); + vfree(env->insn_aux_data); +err_free_env: + kfree(env); + return ret; +} |