diff options
Diffstat (limited to 'kernel/bpf/verifier.c')
| -rw-r--r-- | kernel/bpf/verifier.c | 12742 |
1 files changed, 12742 insertions, 0 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c new file mode 100644 index 000000000..fce2345f6 --- /dev/null +++ b/kernel/bpf/verifier.c @@ -0,0 +1,12742 @@ +// 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/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 "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 pathes 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 ether 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 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); +} + +struct bpf_call_arg_meta { + struct bpf_map *map_ptr; + bool raw_mode; + bool pkt_access; + int regno; + int access_size; + int mem_size; + u64 msize_max_value; + int ref_obj_id; + int func_id; + u32 btf_id; + u32 ret_btf_id; +}; + +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]; +} + +void bpf_verifier_vlog(struct bpf_verifier_log *log, const char *fmt, + va_list args) +{ + unsigned int n; + + n = vscnprintf(log->kbuf, BPF_VERIFIER_TMP_LOG_SIZE, fmt, args); + + WARN_ONCE(n >= BPF_VERIFIER_TMP_LOG_SIZE - 1, + "verifier log line truncated - local buffer too short\n"); + + n = min(log->len_total - log->len_used - 1, n); + log->kbuf[n] = '\0'; + + if (log->level == BPF_LOG_KERNEL) { + pr_err("BPF:%s\n", log->kbuf); + return; + } + if (!copy_to_user(log->ubuf + log->len_used, log->kbuf, n + 1)) + log->len_used += n; + else + log->ubuf = NULL; +} + +static void bpf_vlog_reset(struct bpf_verifier_log *log, u32 new_pos) +{ + char zero = 0; + + if (!bpf_verifier_log_needed(log)) + return; + + log->len_used = new_pos; + if (put_user(zero, log->ubuf + new_pos)) + log->ubuf = NULL; +} + +/* log_level controls verbosity level of eBPF verifier. + * bpf_verifier_log_write() is used to dump the verification trace to the log, + * so the user can figure out what's wrong with the program + */ +__printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env *env, + const char *fmt, ...) +{ + 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); +} +EXPORT_SYMBOL_GPL(bpf_verifier_log_write); + +__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); +} + +__printf(2, 3) void bpf_log(struct bpf_verifier_log *log, + const char *fmt, ...) +{ + va_list args; + + if (!bpf_verifier_log_needed(log)) + return; + + va_start(args, fmt); + bpf_verifier_vlog(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 bool type_is_pkt_pointer(enum bpf_reg_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 reg_type_not_null(enum bpf_reg_type type) +{ + return type == PTR_TO_SOCKET || + type == PTR_TO_TCP_SOCK || + type == PTR_TO_MAP_VALUE || + type == PTR_TO_SOCK_COMMON; +} + +static bool reg_type_may_be_null(enum bpf_reg_type type) +{ + return type == PTR_TO_MAP_VALUE_OR_NULL || + type == PTR_TO_SOCKET_OR_NULL || + type == PTR_TO_SOCK_COMMON_OR_NULL || + type == PTR_TO_TCP_SOCK_OR_NULL || + type == PTR_TO_BTF_ID_OR_NULL || + type == PTR_TO_MEM_OR_NULL || + type == PTR_TO_RDONLY_BUF_OR_NULL || + type == PTR_TO_RDWR_BUF_OR_NULL; +} + +static bool reg_may_point_to_spin_lock(const struct bpf_reg_state *reg) +{ + return reg->type == PTR_TO_MAP_VALUE && + map_value_has_spin_lock(reg->map_ptr); +} + +static bool reg_type_may_be_refcounted_or_null(enum bpf_reg_type type) +{ + return type == PTR_TO_SOCKET || + type == PTR_TO_SOCKET_OR_NULL || + type == PTR_TO_TCP_SOCK || + type == PTR_TO_TCP_SOCK_OR_NULL || + type == PTR_TO_MEM || + type == PTR_TO_MEM_OR_NULL; +} + +static bool arg_type_may_be_refcounted(enum bpf_arg_type type) +{ + return type == ARG_PTR_TO_SOCK_COMMON; +} + +static bool arg_type_may_be_null(enum bpf_arg_type type) +{ + return type == ARG_PTR_TO_MAP_VALUE_OR_NULL || + type == ARG_PTR_TO_MEM_OR_NULL || + type == ARG_PTR_TO_CTX_OR_NULL || + type == ARG_PTR_TO_SOCKET_OR_NULL || + type == ARG_PTR_TO_ALLOC_MEM_OR_NULL; +} + +/* Determine whether the function releases some resources allocated by another + * function call. The first reference type argument will be assumed to be + * released by release_reference(). + */ +static bool is_release_function(enum bpf_func_id func_id) +{ + return func_id == BPF_FUNC_sk_release || + func_id == BPF_FUNC_ringbuf_submit || + func_id == BPF_FUNC_ringbuf_discard; +} + +static bool may_be_acquire_function(enum bpf_func_id func_id) +{ + return 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_map_lookup_elem || + func_id == BPF_FUNC_ringbuf_reserve; +} + +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) + 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_tcp_timewait_sock || + func_id == BPF_FUNC_skc_to_tcp_request_sock; +} + +/* string representation of 'enum bpf_reg_type' */ +static const char * const reg_type_str[] = { + [NOT_INIT] = "?", + [SCALAR_VALUE] = "inv", + [PTR_TO_CTX] = "ctx", + [CONST_PTR_TO_MAP] = "map_ptr", + [PTR_TO_MAP_VALUE] = "map_value", + [PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null", + [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_SOCKET_OR_NULL] = "sock_or_null", + [PTR_TO_SOCK_COMMON] = "sock_common", + [PTR_TO_SOCK_COMMON_OR_NULL] = "sock_common_or_null", + [PTR_TO_TCP_SOCK] = "tcp_sock", + [PTR_TO_TCP_SOCK_OR_NULL] = "tcp_sock_or_null", + [PTR_TO_TP_BUFFER] = "tp_buffer", + [PTR_TO_XDP_SOCK] = "xdp_sock", + [PTR_TO_BTF_ID] = "ptr_", + [PTR_TO_BTF_ID_OR_NULL] = "ptr_or_null_", + [PTR_TO_PERCPU_BTF_ID] = "percpu_ptr_", + [PTR_TO_MEM] = "mem", + [PTR_TO_MEM_OR_NULL] = "mem_or_null", + [PTR_TO_RDONLY_BUF] = "rdonly_buf", + [PTR_TO_RDONLY_BUF_OR_NULL] = "rdonly_buf_or_null", + [PTR_TO_RDWR_BUF] = "rdwr_buf", + [PTR_TO_RDWR_BUF_OR_NULL] = "rdwr_buf_or_null", +}; + +static char slot_type_char[] = { + [STACK_INVALID] = '?', + [STACK_SPILL] = 'r', + [STACK_MISC] = 'm', + [STACK_ZERO] = '0', +}; + +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 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]; +} + +const char *kernel_type_name(u32 id) +{ + return btf_name_by_offset(btf_vmlinux, + btf_type_by_id(btf_vmlinux, id)->name_off); +} + +/* 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 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) +{ + 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; + verbose(env, " R%d", i); + print_liveness(env, reg->live); + verbose(env, "=%s", reg_type_str[t]); + 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, "%lld", reg->var_off.value + reg->off); + } else { + if (t == PTR_TO_BTF_ID || + t == PTR_TO_BTF_ID_OR_NULL || + t == PTR_TO_PERCPU_BTF_ID) + verbose(env, "%s", kernel_type_name(reg->btf_id)); + verbose(env, "(id=%d", reg->id); + if (reg_type_may_be_refcounted_or_null(t)) + verbose(env, ",ref_obj_id=%d", reg->ref_obj_id); + if (t != SCALAR_VALUE) + verbose(env, ",off=%d", reg->off); + if (type_is_pkt_pointer(t)) + verbose(env, ",r=%d", reg->range); + else if (t == CONST_PTR_TO_MAP || + t == PTR_TO_MAP_VALUE || + t == PTR_TO_MAP_VALUE_OR_NULL) + verbose(env, ",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(env, ",imm=%llx", reg->var_off.value); + } else { + if (reg->smin_value != reg->umin_value && + reg->smin_value != S64_MIN) + verbose(env, ",smin_value=%lld", + (long long)reg->smin_value); + if (reg->smax_value != reg->umax_value && + reg->smax_value != S64_MAX) + verbose(env, ",smax_value=%lld", + (long long)reg->smax_value); + if (reg->umin_value != 0) + verbose(env, ",umin_value=%llu", + (unsigned long long)reg->umin_value); + if (reg->umax_value != U64_MAX) + verbose(env, ",umax_value=%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(env, ",var_off=%s", tn_buf); + } + if (reg->s32_min_value != reg->smin_value && + reg->s32_min_value != S32_MIN) + verbose(env, ",s32_min_value=%d", + (int)(reg->s32_min_value)); + if (reg->s32_max_value != reg->smax_value && + reg->s32_max_value != S32_MAX) + verbose(env, ",s32_max_value=%d", + (int)(reg->s32_max_value)); + if (reg->u32_min_value != reg->umin_value && + reg->u32_min_value != U32_MIN) + verbose(env, ",u32_min_value=%d", + (int)(reg->u32_min_value)); + if (reg->u32_max_value != reg->umax_value && + reg->u32_max_value != U32_MAX) + verbose(env, ",u32_max_value=%d", + (int)(reg->u32_max_value)); + } + 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; + verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE); + print_liveness(env, state->stack[i].spilled_ptr.live); + if (is_spilled_reg(&state->stack[i])) { + reg = &state->stack[i].spilled_ptr; + t = reg->type; + verbose(env, "=%s", reg_type_str[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); + } else { + verbose(env, "=%s", types_buf); + } + } + 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); + } + verbose(env, "\n"); +} + +#define COPY_STATE_FN(NAME, COUNT, FIELD, SIZE) \ +static int copy_##NAME##_state(struct bpf_func_state *dst, \ + const struct bpf_func_state *src) \ +{ \ + if (!src->FIELD) \ + return 0; \ + if (WARN_ON_ONCE(dst->COUNT < src->COUNT)) { \ + /* internal bug, make state invalid to reject the program */ \ + memset(dst, 0, sizeof(*dst)); \ + return -EFAULT; \ + } \ + memcpy(dst->FIELD, src->FIELD, \ + sizeof(*src->FIELD) * (src->COUNT / SIZE)); \ + return 0; \ +} +/* copy_reference_state() */ +COPY_STATE_FN(reference, acquired_refs, refs, 1) +/* copy_stack_state() */ +COPY_STATE_FN(stack, allocated_stack, stack, BPF_REG_SIZE) +#undef COPY_STATE_FN + +#define REALLOC_STATE_FN(NAME, COUNT, FIELD, SIZE) \ +static int realloc_##NAME##_state(struct bpf_func_state *state, int size, \ + bool copy_old) \ +{ \ + u32 old_size = state->COUNT; \ + struct bpf_##NAME##_state *new_##FIELD; \ + int slot = size / SIZE; \ + \ + if (size <= old_size || !size) { \ + if (copy_old) \ + return 0; \ + state->COUNT = slot * SIZE; \ + if (!size && old_size) { \ + kfree(state->FIELD); \ + state->FIELD = NULL; \ + } \ + return 0; \ + } \ + new_##FIELD = kmalloc_array(slot, sizeof(struct bpf_##NAME##_state), \ + GFP_KERNEL); \ + if (!new_##FIELD) \ + return -ENOMEM; \ + if (copy_old) { \ + if (state->FIELD) \ + memcpy(new_##FIELD, state->FIELD, \ + sizeof(*new_##FIELD) * (old_size / SIZE)); \ + memset(new_##FIELD + old_size / SIZE, 0, \ + sizeof(*new_##FIELD) * (size - old_size) / SIZE); \ + } \ + state->COUNT = slot * SIZE; \ + kfree(state->FIELD); \ + state->FIELD = new_##FIELD; \ + return 0; \ +} +/* realloc_reference_state() */ +REALLOC_STATE_FN(reference, acquired_refs, refs, 1) +/* realloc_stack_state() */ +REALLOC_STATE_FN(stack, allocated_stack, stack, BPF_REG_SIZE) +#undef REALLOC_STATE_FN + +/* do_check() starts with zero-sized stack in struct bpf_verifier_state to + * make it consume minimal amount of memory. check_stack_write() access from + * the program calls into realloc_func_state() to grow the stack size. + * Note there is a non-zero 'parent' pointer inside bpf_verifier_state + * which realloc_stack_state() copies over. It points to previous + * bpf_verifier_state which is never reallocated. + */ +static int realloc_func_state(struct bpf_func_state *state, int stack_size, + int refs_size, bool copy_old) +{ + int err = realloc_reference_state(state, refs_size, copy_old); + if (err) + return err; + return realloc_stack_state(state, stack_size, copy_old); +} + +/* 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 = realloc_reference_state(state, state->acquired_refs + 1, true); + if (err) + return err; + id = ++env->id_gen; + state->refs[new_ofs].id = id; + state->refs[new_ofs].insn_idx = insn_idx; + + 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) { + 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 int transfer_reference_state(struct bpf_func_state *dst, + struct bpf_func_state *src) +{ + int err = realloc_reference_state(dst, src->acquired_refs, false); + if (err) + return err; + err = copy_reference_state(dst, src); + if (err) + return err; + return 0; +} + +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; + + err = realloc_func_state(dst, src->allocated_stack, src->acquired_refs, + false); + if (err) + return 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; + u32 jmp_sz = sizeof(struct bpf_idx_pair) * src->jmp_history_cnt; + int i, err; + + if (dst_state->jmp_history_cnt < src->jmp_history_cnt) { + kfree(dst_state->jmp_history); + dst_state->jmp_history = kmalloc(jmp_sz, GFP_USER); + if (!dst_state->jmp_history) + return -ENOMEM; + } + memcpy(dst_state->jmp_history, src->jmp_history, jmp_sz); + 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->curframe = src->curframe; + dst_state->active_spin_lock = src->active_spin_lock; + 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; + 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 void update_branch_counts(struct bpf_verifier_env *env, struct bpf_verifier_state *st) +{ + while (st) { + u32 br = --st->branches; + + /* 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.len_used; + 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 +}; + +static void __mark_reg_not_init(const struct bpf_verifier_env *env, + struct bpf_reg_state *reg); + +/* 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 id, off, and union(map_ptr, range) */ + memset(((u8 *)reg) + sizeof(reg->type), 0, + offsetof(struct bpf_reg_state, var_off) - sizeof(reg->type)); + ___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 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; +} + +/* 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(reg->var_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, id, 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->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, u32 btf_id) +{ + 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; + 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; + init_reg_state(env, state); +} + +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 0; + if (env->subprog_cnt >= BPF_MAX_SUBPROGS) { + verbose(env, "too many subprograms\n"); + return -E2BIG; + } + env->subprog_info[env->subprog_cnt++].start = off; + sort(env->subprog_info, env->subprog_cnt, + sizeof(env->subprog_info[0]), cmp_subprogs, NULL); + return 0; +} + +static int check_subprogs(struct bpf_verifier_env *env) +{ + int i, ret, 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; + + /* Add entry function. */ + ret = add_subprog(env, 0); + if (ret < 0) + return ret; + + /* determine subprog starts. The end is one before the next starts */ + for (i = 0; i < insn_cnt; i++) { + if (insn[i].code != (BPF_JMP | BPF_CALL)) + continue; + if (insn[i].src_reg != BPF_PSEUDO_CALL) + continue; + if (!env->bpf_capable) { + verbose(env, + "function calls to other bpf functions are allowed for CAP_BPF and CAP_SYS_ADMIN\n"); + return -EPERM; + } + ret = add_subprog(env, i + insn[i].imm + 1); + 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); + + /* 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].imm == BPF_FUNC_tail_call && + insn[i].src_reg != BPF_PSEUDO_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; + 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_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[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; +} + +/* 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 || class == BPF_JMP || + /* BPF_END always use BPF_ALU class. */ + (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) { + if (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 TRUE if INSN doesn't have explicit value define. */ +static bool insn_no_def(struct bpf_insn *insn) +{ + u8 class = BPF_CLASS(insn->code); + + return (class == BPF_JMP || class == BPF_JMP32 || + class == BPF_STX || class == BPF_ST); +} + +/* 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) +{ + if (insn_no_def(insn)) + return false; + + return !is_reg64(env, insn, 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, u32 regno, + enum reg_arg_type t) +{ + struct bpf_verifier_state *vstate = env->cur_state; + struct bpf_func_state *state = vstate->frame[vstate->curframe]; + struct bpf_insn *insn = env->prog->insnsi + env->insn_idx; + struct bpf_reg_state *reg, *regs = state->regs; + bool rw64; + + if (regno >= MAX_BPF_REG) { + verbose(env, "R%d is invalid\n", regno); + return -EINVAL; + } + + 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; +} + +/* 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; + + cnt++; + p = krealloc(cur->jmp_history, cnt * sizeof(*p), 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. + */ +static int get_prev_insn_idx(struct bpf_verifier_state *st, int i, + u32 *history) +{ + u32 cnt = *history; + + if (cnt && st->jmp_history[cnt - 1].idx == i) { + i = st->jmp_history[cnt - 1].prev_idx; + (*history)--; + } else { + i--; + } + return i; +} + +/* 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. + */ +static int backtrack_insn(struct bpf_verifier_env *env, int idx, + u32 *reg_mask, u64 *stack_mask) +{ + const struct bpf_insn_cbs cbs = { + .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 = 1u << insn->dst_reg; + u32 sreg = 1u << insn->src_reg; + u32 spi; + + if (insn->code == 0) + return 0; + if (env->log.level & BPF_LOG_LEVEL) { + verbose(env, "regs=%x stack=%llx before ", *reg_mask, *stack_mask); + verbose(env, "%d: ", idx); + print_bpf_insn(&cbs, insn, env->allow_ptr_leaks); + } + + if (class == BPF_ALU || class == BPF_ALU64) { + if (!(*reg_mask & 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 + * dreg needs precision after this insn + * sreg needs precision before this insn + */ + *reg_mask &= ~dreg; + *reg_mask |= 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 + */ + *reg_mask &= ~dreg; + } + } else { + if (BPF_SRC(insn->code) == BPF_X) { + /* dreg += sreg + * both dreg and sreg need precision + * before this insn + */ + *reg_mask |= sreg; + } /* else dreg += K + * dreg still needs precision before this insn + */ + } + } else if (class == BPF_LDX) { + if (!(*reg_mask & dreg)) + return 0; + *reg_mask &= ~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; + } + *stack_mask |= 1ull << spi; + } else if (class == BPF_STX || class == BPF_ST) { + if (*reg_mask & 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 (!(*stack_mask & (1ull << spi))) + return 0; + *stack_mask &= ~(1ull << spi); + if (class == BPF_STX) + *reg_mask |= sreg; + } else if (class == BPF_JMP || class == BPF_JMP32) { + if (opcode == BPF_CALL) { + if (insn->src_reg == BPF_PSEUDO_CALL) + return -ENOTSUPP; + /* regular helper call sets R0 */ + *reg_mask &= ~1; + if (*reg_mask & 0x3f) { + /* if backtracing was looking for registers R1-R5 + * they should have been found already. + */ + verbose(env, "BUG regs %x\n", *reg_mask); + WARN_ONCE(1, "verifier backtracking bug"); + return -EFAULT; + } + } else if (opcode == BPF_EXIT) { + return -ENOTSUPP; + } else if (BPF_SRC(insn->code) == BPF_X) { + if (!(*reg_mask & (dreg | 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. + */ + *reg_mask |= (sreg | dreg); + /* 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 (!(*reg_mask & dreg)) + return 0; + *reg_mask &= ~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; + + /* 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) + continue; + reg->precise = true; + } + 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 = true; + } + } + } +} + +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; + } + } +} + +/* + * __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 frame, int regno, + int spi) +{ + struct bpf_verifier_state *st = env->cur_state; + int first_idx = st->first_insn_idx; + int last_idx = env->insn_idx; + struct bpf_func_state *func; + struct bpf_reg_state *reg; + u32 reg_mask = regno >= 0 ? 1u << regno : 0; + u64 stack_mask = spi >= 0 ? 1ull << spi : 0; + bool skip_first = true; + bool new_marks = false; + int i, err; + + if (!env->bpf_capable) + return 0; + + /* 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[frame]; + if (regno >= 0) { + reg = &func->regs[regno]; + if (reg->type != SCALAR_VALUE) { + WARN_ONCE(1, "backtracing misuse"); + return -EFAULT; + } + new_marks = true; + } + + while (spi >= 0) { + if (!is_spilled_reg(&func->stack[spi])) { + stack_mask = 0; + break; + } + reg = &func->stack[spi].spilled_ptr; + if (reg->type != SCALAR_VALUE) { + stack_mask = 0; + break; + } + new_marks = true; + break; + } + + if (!new_marks) + return 0; + if (!reg_mask && !stack_mask) + return 0; + + for (;;) { + DECLARE_BITMAP(mask, 64); + u32 history = st->jmp_history_cnt; + + if (env->log.level & BPF_LOG_LEVEL) + verbose(env, "last_idx %d first_idx %d\n", last_idx, first_idx); + + 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 && + stack_mask == 0 && (reg_mask & ~0x3e) == 0) { + bitmap_from_u64(mask, reg_mask); + for_each_set_bit(i, mask, 32) { + reg = &st->frame[0]->regs[i]; + if (reg->type != SCALAR_VALUE) { + reg_mask &= ~(1u << i); + continue; + } + reg->precise = true; + } + return 0; + } + + verbose(env, "BUG backtracing func entry subprog %d reg_mask %x stack_mask %llx\n", + st->frame[0]->subprogno, reg_mask, stack_mask); + 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, ®_mask, &stack_mask); + } + if (err == -ENOTSUPP) { + mark_all_scalars_precise(env, st); + return 0; + } else if (err) { + return err; + } + if (!reg_mask && !stack_mask) + /* 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; + if (i == first_idx) + break; + i = get_prev_insn_idx(st, i, &history); + 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; + + new_marks = false; + func = st->frame[frame]; + bitmap_from_u64(mask, reg_mask); + for_each_set_bit(i, mask, 32) { + reg = &func->regs[i]; + if (reg->type != SCALAR_VALUE) { + reg_mask &= ~(1u << i); + continue; + } + if (!reg->precise) + new_marks = true; + reg->precise = true; + } + + bitmap_from_u64(mask, stack_mask); + 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, st); + return 0; + } + + if (!is_spilled_reg(&func->stack[i])) { + stack_mask &= ~(1ull << i); + continue; + } + reg = &func->stack[i].spilled_ptr; + if (reg->type != SCALAR_VALUE) { + stack_mask &= ~(1ull << i); + continue; + } + if (!reg->precise) + new_marks = true; + reg->precise = true; + } + if (env->log.level & BPF_LOG_LEVEL) { + print_verifier_state(env, func); + verbose(env, "parent %s regs=%x stack=%llx marks\n", + new_marks ? "didn't have" : "already had", + reg_mask, stack_mask); + } + + if (!reg_mask && !stack_mask) + break; + if (!new_marks) + break; + + last_idx = st->last_insn_idx; + first_idx = st->first_insn_idx; + } + return 0; +} + +static int mark_chain_precision(struct bpf_verifier_env *env, int regno) +{ + return __mark_chain_precision(env, env->cur_state->curframe, regno, -1); +} + +static int mark_chain_precision_frame(struct bpf_verifier_env *env, int frame, int regno) +{ + return __mark_chain_precision(env, frame, regno, -1); +} + +static int mark_chain_precision_stack_frame(struct bpf_verifier_env *env, int frame, int spi) +{ + return __mark_chain_precision(env, frame, -1, spi); +} + +static bool is_spillable_regtype(enum bpf_reg_type type) +{ + switch (type) { + case PTR_TO_MAP_VALUE: + case PTR_TO_MAP_VALUE_OR_NULL: + 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_SOCKET_OR_NULL: + case PTR_TO_SOCK_COMMON: + case PTR_TO_SOCK_COMMON_OR_NULL: + case PTR_TO_TCP_SOCK: + case PTR_TO_TCP_SOCK_OR_NULL: + case PTR_TO_XDP_SOCK: + case PTR_TO_BTF_ID: + case PTR_TO_BTF_ID_OR_NULL: + case PTR_TO_RDONLY_BUF: + case PTR_TO_RDONLY_BUF_OR_NULL: + case PTR_TO_RDWR_BUF: + case PTR_TO_RDWR_BUF_OR_NULL: + case PTR_TO_PERCPU_BTF_ID: + case PTR_TO_MEM: + case PTR_TO_MEM_OR_NULL: + 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; + + err = realloc_func_state(state, round_up(slot + 1, BPF_REG_SIZE), + state->acquired_refs, true); + if (err) + return err; + /* 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; + } + + 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 conervative. + * 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. */ + if (is_spilled_reg(&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; + 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)) + writing_zero = true; + + err = realloc_func_state(state, round_up(-min_off, BPF_REG_SIZE), + state->acquired_refs, true); + 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]; + + 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; + 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; + + 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; + 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; + 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 stack_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 stack_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_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. + */ + if (env->log.level & BPF_LOG_LEVEL) + print_verifier_state(env, state); + + /* 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; +} + +/* 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) +{ + 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; + int err; + + err = check_mem_region_access(env, regno, off, size, map->value_size, + zero_size_allowed); + if (err) + return err; + + if (map_value_has_spin_lock(map)) { + u32 lock = map->spin_lock_off; + + /* if any part of struct bpf_spin_lock 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 < lock + sizeof(struct bpf_spin_lock) && + lock < reg->umax_value + off + size) { + verbose(env, "bpf_spin_lock cannot be accessed directly by load/store\n"); + return -EACCES; + } + } + return err; +} + +#define MAX_PACKET_OFF 0xffff + +static enum bpf_prog_type resolve_prog_type(struct bpf_prog *prog) +{ + return prog->aux->dst_prog ? prog->aux->dst_prog->type : prog->type; +} + +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, + 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 (*reg_type == PTR_TO_BTF_ID || *reg_type == PTR_TO_BTF_ID_OR_NULL) + *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[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 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_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); +} + +static int update_stack_depth(struct bpf_verifier_env *env, + const struct bpf_func_state *func, + int off) +{ + u16 stack = env->subprog_info[func->subprogno].stack_depth; + + if (stack >= -off) + return 0; + + /* update known max for given subprogram */ + env->subprog_info[func->subprogno].stack_depth = -off; + return 0; +} + +/* 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(struct bpf_verifier_env *env) +{ + int depth = 0, frame = 0, idx = 0, i = 0, subprog_end; + struct bpf_subprog_info *subprog = env->subprog_info; + struct bpf_insn *insn = env->prog->insnsi; + bool tail_call_reachable = false; + int ret_insn[MAX_CALL_FRAMES]; + int ret_prog[MAX_CALL_FRAMES]; + int j; + +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++) { + if (insn[i].code != (BPF_JMP | BPF_CALL)) + continue; + if (insn[i].src_reg != BPF_PSEUDO_CALL) + continue; + /* remember insn and function to return to */ + ret_insn[frame] = i + 1; + ret_prog[frame] = idx; + + /* find the callee */ + i = i + insn[i].imm + 1; + idx = find_subprog(env, i); + if (idx < 0) { + WARN_ONCE(1, "verifier bug. No program starts at insn %d\n", + i); + return -EFAULT; + } + + 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; +} + +#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 + +int check_ctx_reg(struct bpf_verifier_env *env, + const struct bpf_reg_state *reg, int regno) +{ + /* Access to ctx or passing it to a helper is only allowed in + * its original, unmodified form. + */ + + if (reg->off) { + verbose(env, "dereference of modified ctx ptr R%d off=%d disallowed\n", + 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 ctx access var_off=%s disallowed\n", tn_buf); + return -EACCES; + } + + return 0; +} + +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, + const char *buf_info, + u32 *max_access) +{ + 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 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) +{ + 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 = (u64)*(u8 *)ptr; + break; + case sizeof(u16): + *val = (u64)*(u16 *)ptr; + break; + case sizeof(u32): + *val = (u64)*(u32 *)ptr; + break; + case sizeof(u64): + *val = *(u64 *)ptr; + break; + default: + return -EINVAL; + } + return 0; +} + +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(btf_vmlinux, reg->btf_id); + const char *tname = btf_name_by_offset(btf_vmlinux, t->name_off); + u32 btf_id; + int ret; + + 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 (env->ops->btf_struct_access) { + ret = env->ops->btf_struct_access(&env->log, t, off, size, + atype, &btf_id); + } else { + if (atype != BPF_READ) { + verbose(env, "only read is supported\n"); + return -EACCES; + } + + ret = btf_struct_access(&env->log, t, off, size, atype, + &btf_id); + } + + if (ret < 0) + return ret; + + if (atype == BPF_READ && value_regno >= 0) + mark_btf_ld_reg(env, regs, value_regno, ret, btf_id); + + 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; + 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_to_map_access) { + verbose(env, + "%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; + } + + ret = btf_struct_access(&env->log, t, off, size, atype, &btf_id); + if (ret < 0) + return ret; + + if (value_regno >= 0) + mark_btf_ld_reg(env, regs, value_regno, ret, btf_id); + + 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(int off, + struct bpf_func_state *state, + enum bpf_access_type t) +{ + int min_valid_off; + + if (t == BPF_WRITE) + 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 stack_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); + int 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 = 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(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; +} + +/* 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) +{ + struct bpf_reg_state *regs = cur_regs(env); + struct bpf_reg_state *reg = regs + regno; + struct bpf_func_state *state; + 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_VALUE) { + 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); + if (!err && 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); + 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 (reg->type == PTR_TO_MEM) { + 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 && t == BPF_READ && value_regno >= 0) + mark_reg_unknown(env, regs, value_regno); + } else if (reg->type == PTR_TO_CTX) { + enum bpf_reg_type reg_type = SCALAR_VALUE; + 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_ctx_reg(env, reg, regno); + if (err < 0) + return err; + + err = check_ctx_access(env, insn_idx, off, size, t, ®_type, &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 (reg_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 (reg_type == PTR_TO_BTF_ID || + reg_type == PTR_TO_BTF_ID_OR_NULL) + 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; + + state = func(env, reg); + err = update_stack_depth(env, state, off); + 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[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 (reg->type == PTR_TO_BTF_ID) { + 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 (reg->type == PTR_TO_RDONLY_BUF) { + if (t == BPF_WRITE) { + verbose(env, "R%d cannot write into %s\n", + regno, reg_type_str[reg->type]); + return -EACCES; + } + err = check_buffer_access(env, reg, regno, off, size, false, + "rdonly", + &env->prog->aux->max_rdonly_access); + if (!err && value_regno >= 0) + mark_reg_unknown(env, regs, value_regno); + } else if (reg->type == PTR_TO_RDWR_BUF) { + err = check_buffer_access(env, reg, regno, off, size, false, + "rdwr", + &env->prog->aux->max_rdwr_access); + if (!err && t == BPF_READ && value_regno >= 0) + mark_reg_unknown(env, regs, value_regno); + } else { + verbose(env, "R%d invalid mem access '%s'\n", regno, + reg_type_str[reg->type]); + return -EACCES; + } + + if (!err && size < BPF_REG_SIZE && value_regno >= 0 && t == BPF_READ && + regs[value_regno].type == SCALAR_VALUE) { + /* b/h/w load zero-extends, mark upper bits as known 0 */ + coerce_reg_to_size(®s[value_regno], size); + } + return err; +} + +static int check_xadd(struct bpf_verifier_env *env, int insn_idx, struct bpf_insn *insn) +{ + int err; + + if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) || + insn->imm != 0) { + verbose(env, "BPF_XADD 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; + + 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_XADD stores into R%d %s is not allowed\n", + insn->dst_reg, + reg_type_str[reg_state(env, insn->dst_reg)->type]); + return -EACCES; + } + + /* check whether atomic_add can read the memory */ + err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, + BPF_SIZE(insn->code), BPF_READ, -1, true); + if (err) + return err; + + /* check whether atomic_add can write into the same memory */ + return check_mem_access(env, insn_idx, insn->dst_reg, insn->off, + BPF_SIZE(insn->code), BPF_WRITE, -1, true); +} + +/* 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, 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 stack_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) { + 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) + goto err; + stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE]; + if (*stype == STACK_MISC) + goto mark; + if (*stype == STACK_ZERO) { + 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 == PTR_TO_BTF_ID) + 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; + } + +err: + 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); + } + return update_stack_depth(env, state, min_off); +} + +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]; + + switch (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_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); + case PTR_TO_MEM: + return check_mem_region_access(env, regno, reg->off, + access_size, reg->mem_size, + zero_size_allowed); + case PTR_TO_RDONLY_BUF: + if (meta && meta->raw_mode) + return -EACCES; + return check_buffer_access(env, reg, regno, reg->off, + access_size, zero_size_allowed, + "rdonly", + &env->prog->aux->max_rdonly_access); + case PTR_TO_RDWR_BUF: + return check_buffer_access(env, reg, regno, reg->off, + access_size, zero_size_allowed, + "rdwr", + &env->prog->aux->max_rdwr_access); + case PTR_TO_STACK: + return check_stack_range_initialized( + env, + regno, reg->off, access_size, + zero_size_allowed, ACCESS_HELPER, meta); + 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 expected=%s\n", regno, + reg_type_str[reg->type], + reg_type_str[PTR_TO_STACK]); + return -EACCES; + } +} + +/* Implementation details: + * bpf_map_lookup returns PTR_TO_MAP_VALUE_OR_NULL + * Two bpf_map_lookups (even with the same key) will have different reg->id. + * For traditional PTR_TO_MAP_VALUE 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. + * 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_spin_lock remembers which map value element 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); + 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_spin_lock 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_spin_lock\n", + map->name); + return -EINVAL; + } + if (!map_value_has_spin_lock(map)) { + if (map->spin_lock_off == -E2BIG) + verbose(env, + "map '%s' has more than one 'struct bpf_spin_lock'\n", + map->name); + else if (map->spin_lock_off == -ENOENT) + verbose(env, + "map '%s' doesn't have 'struct bpf_spin_lock'\n", + map->name); + else + verbose(env, + "map '%s' is not a struct type or bpf_spin_lock is mangled\n", + map->name); + return -EINVAL; + } + if (map->spin_lock_off != val + reg->off) { + verbose(env, "off %lld doesn't point to 'struct bpf_spin_lock'\n", + val + reg->off); + return -EINVAL; + } + if (is_lock) { + if (cur->active_spin_lock) { + verbose(env, + "Locking two bpf_spin_locks are not allowed\n"); + return -EINVAL; + } + cur->active_spin_lock = reg->id; + } else { + if (!cur->active_spin_lock) { + verbose(env, "bpf_spin_unlock without taking a lock\n"); + return -EINVAL; + } + if (cur->active_spin_lock != reg->id) { + verbose(env, "bpf_spin_unlock of different lock\n"); + return -EINVAL; + } + cur->active_spin_lock = 0; + } + return 0; +} + +static bool arg_type_is_mem_ptr(enum bpf_arg_type type) +{ + return type == ARG_PTR_TO_MEM || + type == ARG_PTR_TO_MEM_OR_NULL || + type == ARG_PTR_TO_UNINIT_MEM; +} + +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_alloc_size(enum bpf_arg_type type) +{ + return type == ARG_CONST_ALLOC_SIZE_OR_ZERO; +} + +static bool arg_type_is_int_ptr(enum bpf_arg_type type) +{ + return type == ARG_PTR_TO_INT || + type == ARG_PTR_TO_LONG; +} + +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; + + default: + break; + } + return 0; +} + +struct bpf_reg_types { + const enum bpf_reg_type types[10]; + u32 *btf_id; +}; + +static const struct bpf_reg_types map_key_value_types = { + .types = { + PTR_TO_STACK, + PTR_TO_PACKET, + PTR_TO_PACKET_META, + PTR_TO_MAP_VALUE, + }, +}; + +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, + }, + .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_VALUE, + PTR_TO_MEM, + PTR_TO_RDONLY_BUF, + PTR_TO_RDWR_BUF, + }, +}; + +static const struct bpf_reg_types int_ptr_types = { + .types = { + PTR_TO_STACK, + PTR_TO_PACKET, + PTR_TO_PACKET_META, + PTR_TO_MAP_VALUE, + }, +}; + +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 alloc_mem_types = { .types = { PTR_TO_MEM } }; +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 } }; +static const struct bpf_reg_types spin_lock_types = { .types = { PTR_TO_MAP_VALUE } }; +static const struct bpf_reg_types percpu_btf_ptr_types = { .types = { PTR_TO_PERCPU_BTF_ID } }; + +static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = { + [ARG_PTR_TO_MAP_KEY] = &map_key_value_types, + [ARG_PTR_TO_MAP_VALUE] = &map_key_value_types, + [ARG_PTR_TO_UNINIT_MAP_VALUE] = &map_key_value_types, + [ARG_PTR_TO_MAP_VALUE_OR_NULL] = &map_key_value_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_CTX_OR_NULL] = &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_SOCKET_OR_NULL] = &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_MEM_OR_NULL] = &mem_types, + [ARG_PTR_TO_UNINIT_MEM] = &mem_types, + [ARG_PTR_TO_ALLOC_MEM] = &alloc_mem_types, + [ARG_PTR_TO_ALLOC_MEM_OR_NULL] = &alloc_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, +}; + +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_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[arg_type]; + if (!compatible) { + verbose(env, "verifier internal error: unsupported arg type %d\n", arg_type); + return -EFAULT; + } + + 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[type]); + for (j = 0; j + 1 < i; j++) + verbose(env, "%s, ", reg_type_str[compatible->types[j]]); + verbose(env, "%s\n", reg_type_str[compatible->types[j]]); + return -EACCES; + +found: + if (type == PTR_TO_BTF_ID) { + 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 (!btf_struct_ids_match(&env->log, reg->off, reg->btf_id, + *arg_btf_id)) { + verbose(env, "R%d is of type %s but %s is expected\n", + regno, kernel_type_name(reg->btf_id), + kernel_type_name(*arg_btf_id)); + return -EACCES; + } + + if (!tnum_is_const(reg->var_off) || reg->var_off.value) { + verbose(env, "R%d is a pointer to in-kernel struct with non-zero offset\n", + regno); + return -EACCES; + } + } + + return 0; +} + +static int check_func_arg(struct bpf_verifier_env *env, u32 arg, + struct bpf_call_arg_meta *meta, + const struct bpf_func_proto *fn) +{ + 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; + 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 (arg_type == ARG_PTR_TO_MAP_VALUE || + arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE || + arg_type == ARG_PTR_TO_MAP_VALUE_OR_NULL) { + err = resolve_map_arg_type(env, meta, &arg_type); + if (err) + return err; + } + + if (register_is_null(reg) && arg_type_may_be_null(arg_type)) + /* A NULL register has a SCALAR_VALUE type, so skip + * type checking. + */ + goto skip_type_check; + + err = check_reg_type(env, regno, arg_type, fn->arg_btf_id[arg]); + if (err) + return err; + + if (type == PTR_TO_CTX) { + err = check_ctx_reg(env, reg, regno); + if (err < 0) + return err; + } + +skip_type_check: + 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; + } + + if (arg_type == ARG_CONST_MAP_PTR) { + /* bpf_map_xxx(map_ptr) call: remember that map_ptr */ + meta->map_ptr = reg->map_ptr; + } else if (arg_type == 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); + } else if (arg_type == ARG_PTR_TO_MAP_VALUE || + (arg_type == ARG_PTR_TO_MAP_VALUE_OR_NULL && + !register_is_null(reg)) || + arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE) { + /* 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 == ARG_PTR_TO_UNINIT_MAP_VALUE); + err = check_helper_mem_access(env, regno, + meta->map_ptr->value_size, false, + meta); + } else if (arg_type == 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_id = reg->btf_id; + } else if (arg_type == ARG_PTR_TO_SPIN_LOCK) { + if (meta->func_id == BPF_FUNC_spin_lock) { + if (process_spin_lock(env, regno, true)) + return -EACCES; + } else if (meta->func_id == BPF_FUNC_spin_unlock) { + if (process_spin_lock(env, regno, false)) + return -EACCES; + } else { + verbose(env, "verifier internal error\n"); + return -EFAULT; + } + } else if (arg_type_is_mem_ptr(arg_type)) { + /* The access to this pointer is only checked when we hit the + * next is_mem_size argument below. + */ + meta->raw_mode = (arg_type == ARG_PTR_TO_UNINIT_MEM); + } else if (arg_type_is_mem_size(arg_type)) { + bool zero_size_allowed = (arg_type == ARG_CONST_SIZE_OR_ZERO); + + /* 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); + } else if (arg_type_is_alloc_size(arg_type)) { + if (!tnum_is_const(reg->var_off)) { + verbose(env, "R%d unbounded size, use 'var &= const' or 'if (var < const)'\n", + regno); + return -EACCES; + } + meta->mem_size = reg->var_off.value; + } else if (arg_type_is_int_ptr(arg_type)) { + 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); + } + + 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 && IS_ENABLED(CONFIG_X86_64); +} + +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) + 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) + goto error; + break; + case BPF_MAP_TYPE_INODE_STORAGE: + if (func_id != BPF_FUNC_inode_storage_get && + func_id != BPF_FUNC_inode_storage_delete) + 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: + if (map->map_type != BPF_MAP_TYPE_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_peek_elem: + case BPF_FUNC_map_pop_elem: + case BPF_FUNC_map_push_elem: + if (map->map_type != BPF_MAP_TYPE_QUEUE && + map->map_type != BPF_MAP_TYPE_STACK) + 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; + 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(enum bpf_arg_type arg_curr, + enum bpf_arg_type arg_next) +{ + return (arg_type_is_mem_ptr(arg_curr) && + !arg_type_is_mem_size(arg_next)) || + (!arg_type_is_mem_ptr(arg_curr) && + arg_type_is_mem_size(arg_next)); +} + +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) || + arg_type_is_mem_ptr(fn->arg5_type) || + check_args_pair_invalid(fn->arg1_type, fn->arg2_type) || + check_args_pair_invalid(fn->arg2_type, fn->arg3_type) || + check_args_pair_invalid(fn->arg3_type, fn->arg4_type) || + check_args_pair_invalid(fn->arg4_type, fn->arg5_type)) + return false; + + return true; +} + +static bool check_refcount_ok(const struct bpf_func_proto *fn, int func_id) +{ + int count = 0; + + if (arg_type_may_be_refcounted(fn->arg1_type)) + count++; + if (arg_type_may_be_refcounted(fn->arg2_type)) + count++; + if (arg_type_may_be_refcounted(fn->arg3_type)) + count++; + if (arg_type_may_be_refcounted(fn->arg4_type)) + count++; + if (arg_type_may_be_refcounted(fn->arg5_type)) + count++; + + /* A reference acquiring function cannot acquire + * another refcounted ptr. + */ + if (may_be_acquire_function(func_id) && count) + return false; + + /* We only support one arg being unreferenced at the moment, + * which is sufficient for the helper functions we have right now. + */ + return count <= 1; +} + +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 (fn->arg_type[i] == ARG_PTR_TO_BTF_ID && !fn->arg_btf_id[i]) + return false; + + if (fn->arg_type[i] != ARG_PTR_TO_BTF_ID && fn->arg_btf_id[i]) + 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) && + check_refcount_ok(fn, func_id) ? 0 : -EINVAL; +} + +/* Packet data might have moved, any old PTR_TO_PACKET[_META,_END] + * are now invalid, so turn them into unknown SCALAR_VALUE. + */ +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)) + __mark_reg_unknown(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) { + if (!env->allow_ptr_leaks) + __mark_reg_not_init(env, reg); + else + __mark_reg_unknown(env, reg); + } + })); + + return 0; +} + +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, caller_saved[i], DST_OP_NO_MARK); + } +} + +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_info_aux *func_info_aux; + struct bpf_func_state *caller, *callee; + int i, err, subprog, target_insn; + bool is_global = false; + + if (state->curframe + 1 >= MAX_CALL_FRAMES) { + verbose(env, "the call stack of %d frames is too deep\n", + state->curframe + 2); + return -E2BIG; + } + + target_insn = *insn_idx + insn->imm; + subprog = find_subprog(env, target_insn + 1); + if (subprog < 0) { + verbose(env, "verifier bug. No program starts at insn %d\n", + target_insn + 1); + return -EFAULT; + } + + caller = state->frame[state->curframe]; + if (state->frame[state->curframe + 1]) { + verbose(env, "verifier bug. Frame %d already allocated\n", + state->curframe + 1); + return -EFAULT; + } + + func_info_aux = env->prog->aux->func_info_aux; + if (func_info_aux) + is_global = func_info_aux[subprog].linkage == BTF_FUNC_GLOBAL; + err = btf_check_func_arg_match(env, subprog, caller->regs); + if (err == -EFAULT) + return err; + if (is_global) { + if (err) { + verbose(env, "Caller passes invalid args into func#%d\n", + subprog); + return err; + } else { + 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; + } + } + + 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 */ + *insn_idx /* callsite */, + state->curframe + 1 /* frameno within this callchain */, + subprog /* subprog number within this prog */); + + /* Transfer references to the callee */ + err = transfer_reference_state(callee, caller); + if (err) + return err; + + /* 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]; + + clear_caller_saved_regs(env, caller->regs); + + /* only increment it after check_reg_arg() finished */ + state->curframe++; + + /* and go analyze first insn of the callee */ + *insn_idx = target_insn; + + if (env->log.level & BPF_LOG_LEVEL) { + verbose(env, "caller:\n"); + print_verifier_state(env, caller); + verbose(env, "callee:\n"); + print_verifier_state(env, callee); + } + return 0; +} + +static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx) +{ + struct bpf_verifier_state *state = env->cur_state; + struct bpf_func_state *caller, *callee; + struct bpf_reg_state *r0; + 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; + } + + state->curframe--; + caller = state->frame[state->curframe]; + /* return to the caller whatever r0 had in the callee */ + caller->regs[BPF_REG_0] = *r0; + + /* Transfer references to the caller */ + err = transfer_reference_state(caller, callee); + if (err) + return err; + + *insn_idx = callee->callsite + 1; + if (env->log.level & BPF_LOG_LEVEL) { + verbose(env, "returning from callee:\n"); + print_verifier_state(env, callee); + verbose(env, "to caller at %d:\n", *insn_idx); + print_verifier_state(env, caller); + } + /* clear everything in the callee */ + free_func_state(callee); + state->frame[state->curframe + 1] = NULL; + 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 || + (func_id != BPF_FUNC_get_stack && + func_id != BPF_FUNC_probe_read_str && + func_id != BPF_FUNC_probe_read_kernel_str && + func_id != BPF_FUNC_probe_read_user_str)) + return; + + 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); +} + +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) + 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); + int i; + + for (i = 0; i < state->acquired_refs; i++) { + verbose(env, "Unreleased reference id=%d alloc_insn=%d\n", + state->refs[i].id, state->refs[i].insn_idx); + } + return state->acquired_refs ? -EINVAL : 0; +} + +static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn_idx) +{ + const struct bpf_func_proto *fn = NULL; + struct bpf_reg_state *regs; + struct bpf_call_arg_meta meta; + bool changes_data; + int i, err; + + /* find function prototype */ + 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; + } + + /* 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; + } + + meta.func_id = func_id; + /* check args */ + for (i = 0; i < 5; i++) { + err = check_func_arg(env, i, &meta, fn); + 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); + if (err) + return err; + } + + if (func_id == BPF_FUNC_tail_call) { + err = check_reference_leak(env); + if (err) { + verbose(env, "tail_call would lead to reference leak\n"); + return err; + } + } else if (is_release_function(func_id)) { + err = release_reference(env, meta.ref_obj_id); + if (err) { + verbose(env, "func %s#%d reference has not been acquired before\n", + func_id_name(func_id), func_id); + return err; + } + } + + regs = cur_regs(env); + + /* 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 (func_id == BPF_FUNC_get_local_storage && + !register_is_null(®s[BPF_REG_2])) { + verbose(env, "get_local_storage() doesn't support non-zero flags\n"); + return -EINVAL; + } + + /* 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) */ + if (fn->ret_type == RET_INTEGER) { + /* sets type to SCALAR_VALUE */ + mark_reg_unknown(env, regs, BPF_REG_0); + } else if (fn->ret_type == RET_VOID) { + regs[BPF_REG_0].type = NOT_INIT; + } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL || + fn->ret_type == 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; + if (fn->ret_type == RET_PTR_TO_MAP_VALUE) { + regs[BPF_REG_0].type = PTR_TO_MAP_VALUE; + if (map_value_has_spin_lock(meta.map_ptr)) + regs[BPF_REG_0].id = ++env->id_gen; + } else { + regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL; + } + } else if (fn->ret_type == RET_PTR_TO_SOCKET_OR_NULL) { + mark_reg_known_zero(env, regs, BPF_REG_0); + regs[BPF_REG_0].type = PTR_TO_SOCKET_OR_NULL; + } else if (fn->ret_type == RET_PTR_TO_SOCK_COMMON_OR_NULL) { + mark_reg_known_zero(env, regs, BPF_REG_0); + regs[BPF_REG_0].type = PTR_TO_SOCK_COMMON_OR_NULL; + } else if (fn->ret_type == RET_PTR_TO_TCP_SOCK_OR_NULL) { + mark_reg_known_zero(env, regs, BPF_REG_0); + regs[BPF_REG_0].type = PTR_TO_TCP_SOCK_OR_NULL; + } else if (fn->ret_type == RET_PTR_TO_ALLOC_MEM_OR_NULL) { + mark_reg_known_zero(env, regs, BPF_REG_0); + regs[BPF_REG_0].type = PTR_TO_MEM_OR_NULL; + regs[BPF_REG_0].mem_size = meta.mem_size; + } else if (fn->ret_type == RET_PTR_TO_MEM_OR_BTF_ID_OR_NULL || + fn->ret_type == 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(btf_vmlinux, 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(btf_vmlinux, t, &tsize); + if (IS_ERR(ret)) { + tname = btf_name_by_offset(btf_vmlinux, 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 = + fn->ret_type == RET_PTR_TO_MEM_OR_BTF_ID ? + PTR_TO_MEM : PTR_TO_MEM_OR_NULL; + regs[BPF_REG_0].mem_size = tsize; + } else { + regs[BPF_REG_0].type = + fn->ret_type == RET_PTR_TO_MEM_OR_BTF_ID ? + PTR_TO_BTF_ID : PTR_TO_BTF_ID_OR_NULL; + regs[BPF_REG_0].btf_id = meta.ret_btf_id; + } + } else if (fn->ret_type == RET_PTR_TO_BTF_ID_OR_NULL) { + int ret_btf_id; + + mark_reg_known_zero(env, regs, BPF_REG_0); + regs[BPF_REG_0].type = PTR_TO_BTF_ID_OR_NULL; + ret_btf_id = *fn->ret_btf_id; + if (ret_btf_id == 0) { + verbose(env, "invalid return type %d of func %s#%d\n", + fn->ret_type, func_id_name(func_id), func_id); + return -EINVAL; + } + regs[BPF_REG_0].btf_id = ret_btf_id; + } else { + verbose(env, "unknown return type %d of func %s#%d\n", + fn->ret_type, func_id_name(func_id), func_id); + return -EINVAL; + } + + if (reg_type_may_be_null(regs[BPF_REG_0].type)) + regs[BPF_REG_0].id = ++env->id_gen; + + if (is_ptr_cast_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 (changes_data) + clear_all_pkt_pointers(env); + 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[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[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[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[type]); + return false; + } + + return true; +} + +static struct bpf_insn_aux_data *cur_aux(struct bpf_verifier_env *env) +{ + return &env->insn_aux_data[env->insn_idx]; +} + +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 fixup_bpf_calls(). */ + 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)) { + 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; + } + + switch (ptr_reg->type) { + case PTR_TO_MAP_VALUE_OR_NULL: + verbose(env, "R%d pointer arithmetic on %s prohibited, null-check it first\n", + dst, reg_type_str[ptr_reg->type]); + return -EACCES; + 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: +reject: + verbose(env, "R%d pointer arithmetic on %s prohibited\n", + dst, reg_type_str[ptr_reg->type]); + return -EACCES; + default: + if (reg_type_may_be_null(ptr_reg->type)) + goto reject; + 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 */ + dst_reg->raw = 0; + } + 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) + dst_reg->raw = 0; + } + 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 bounts 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 bounts 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); + verbose(env, "verifier internal error: unexpected ptr_reg\n"); + return -EINVAL; + } + if (WARN_ON(!src_reg)) { + print_verifier_state(env, state); + 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) != 0 || + 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) { + 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 || insn->off != 0) { + 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; + + if (BPF_CLASS(insn->code) == BPF_ALU64) { + /* case: R1 = R2 + * copy register state to dest reg + */ + if (src_reg->type == SCALAR_VALUE && !src_reg->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 { + /* 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) { + copy_register_state(dst_reg, src_reg); + /* Make sure ID is cleared otherwise + * dst_reg min/max could be incorrectly + * propagated into src_reg by find_equal_scalars() + */ + dst_reg->id = 0; + dst_reg->live |= REG_LIVE_WRITTEN; + dst_reg->subreg_def = env->insn_idx + 1; + } 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 != 0) { + 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 != 0) { + 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); + break; + case BPF_JNE: + if (tnum_is_const(subreg)) + return !tnum_equals_const(subreg, val); + 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); + break; + case BPF_JNE: + if (tnum_is_const(reg->var_off)) + return !tnum_equals_const(reg->var_off, val); + 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_type_not_null(reg->type)) + 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 (reg_type_may_be_null(reg->type) && reg->id == id && + !WARN_ON_ONCE(!reg->id)) { + if (WARN_ON_ONCE(reg->smin_value || reg->smax_value || + !tnum_equals_const(reg->var_off, 0) || + reg->off)) { + /* 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. + */ + return; + } + if (is_null) { + reg->type = SCALAR_VALUE; + } else if (reg->type == PTR_TO_MAP_VALUE_OR_NULL) { + 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; + } 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; + } + } else if (reg->type == PTR_TO_SOCKET_OR_NULL) { + reg->type = PTR_TO_SOCKET; + } else if (reg->type == PTR_TO_SOCK_COMMON_OR_NULL) { + reg->type = PTR_TO_SOCK_COMMON; + } else if (reg->type == PTR_TO_TCP_SOCK_OR_NULL) { + reg->type = PTR_TO_TCP_SOCK; + } else if (reg->type == PTR_TO_BTF_ID_OR_NULL) { + reg->type = PTR_TO_BTF_ID; + } else if (reg->type == PTR_TO_MEM_OR_NULL) { + reg->type = PTR_TO_MEM; + } else if (reg->type == PTR_TO_RDONLY_BUF_OR_NULL) { + reg->type = PTR_TO_RDONLY_BUF; + } else if (reg->type == PTR_TO_RDWR_BUF_OR_NULL) { + reg->type = PTR_TO_RDWR_BUF; + } + if (is_null) { + /* 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; + } else 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; + 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; + } + + 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; + + if (is_pointer_value(env, insn->src_reg)) { + verbose(env, "R%d pointer comparison prohibited\n", + insn->src_reg); + return -EACCES; + } + src_reg = ®s[insn->src_reg]; + } else { + if (insn->src_reg != BPF_REG_0) { + verbose(env, "BPF_JMP/JMP32 uses reserved fields\n"); + 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]; + 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 (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; + *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; + 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, but we don't support that right now), 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]); + } + + /* 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) && + reg_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_verifier_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; + } + + if (insn->src_reg == BPF_PSEUDO_BTF_ID) { + mark_reg_known_zero(env, regs, insn->dst_reg); + + dst_reg->type = aux->btf_var.reg_type; + switch (dst_reg->type) { + case PTR_TO_MEM: + dst_reg->mem_size = aux->btf_var.mem_size; + break; + case PTR_TO_BTF_ID: + case PTR_TO_PERCPU_BTF_ID: + dst_reg->btf_id = aux->btf_var.btf_id; + break; + default: + verbose(env, "bpf verifier is misconfigured\n"); + return -EFAULT; + } + return 0; + } + + map = env->used_maps[aux->map_index]; + mark_reg_known_zero(env, regs, insn->dst_reg); + dst_reg->map_ptr = map; + + if (insn->src_reg == BPF_PSEUDO_MAP_VALUE) { + dst_reg->type = PTR_TO_MAP_VALUE; + dst_reg->off = aux->map_off; + if (map_value_has_spin_lock(map)) + dst_reg->id = ++env->id_gen; + } else if (insn->src_reg == BPF_PSEUDO_MAP_FD) { + 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_spin_lock) { + verbose(env, "BPF_LD_[ABS|IND] cannot be used inside bpf_spin_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_ctx_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); + enum bpf_prog_type prog_type = resolve_prog_type(env->prog); + int err; + const bool is_subprog = env->cur_state->frame[0]->subprogno; + + /* LSM and struct_ops func-ptr's return type could be "void" */ + if (!is_subprog && + (prog_type == BPF_PROG_TYPE_STRUCT_OPS || + prog_type == BPF_PROG_TYPE_LSM) && + !prog->aux->attach_func_proto->type) + return 0; + + /* eBPF calling convetion 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 (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[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); + 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_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[reg->type]); + return -EINVAL; + } + + if (!tnum_in(range, reg->var_off)) { + char tn_buf[48]; + + verbose(env, "At program exit the register R0 "); + 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); + 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.pop() + * 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 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 void init_explored_state(struct bpf_verifier_env *env, int idx) +{ + env->insn_aux_data[idx].prune_point = true; +} + +/* 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, + bool loop_ok) +{ + int *insn_stack = env->cfg.insn_stack; + int *insn_state = env->cfg.insn_state; + + if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH)) + return 0; + + if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH)) + return 0; + + 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 */ + init_explored_state(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 1; + } else if ((insn_state[w] & 0xF0) == DISCOVERED) { + if (loop_ok && env->bpf_capable) + return 0; + 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 0; +} + +/* 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) +{ + struct bpf_insn *insns = env->prog->insnsi; + int insn_cnt = env->prog->len; + int *insn_stack, *insn_state; + int ret = 0; + int i, t; + + 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; + +peek_stack: + if (env->cfg.cur_stack == 0) + goto check_state; + t = insn_stack[env->cfg.cur_stack - 1]; + + if (BPF_CLASS(insns[t].code) == BPF_JMP || + BPF_CLASS(insns[t].code) == BPF_JMP32) { + u8 opcode = BPF_OP(insns[t].code); + + if (opcode == BPF_EXIT) { + goto mark_explored; + } else if (opcode == BPF_CALL) { + ret = push_insn(t, t + 1, FALLTHROUGH, env, false); + if (ret == 1) + goto peek_stack; + else if (ret < 0) + goto err_free; + if (t + 1 < insn_cnt) + init_explored_state(env, t + 1); + if (insns[t].src_reg == BPF_PSEUDO_CALL) { + init_explored_state(env, t); + ret = push_insn(t, t + insns[t].imm + 1, BRANCH, + env, false); + if (ret == 1) + goto peek_stack; + else if (ret < 0) + goto err_free; + } + } else if (opcode == BPF_JA) { + if (BPF_SRC(insns[t].code) != BPF_K) { + ret = -EINVAL; + goto err_free; + } + /* unconditional jump with single edge */ + ret = push_insn(t, t + insns[t].off + 1, + FALLTHROUGH, env, true); + if (ret == 1) + goto peek_stack; + else if (ret < 0) + goto err_free; + /* unconditional jmp is not a good pruning point, + * but it's marked, since backtracking needs + * to record jmp history in is_state_visited(). + */ + init_explored_state(env, t + insns[t].off + 1); + /* tell verifier to check for equivalent states + * after every call and jump + */ + if (t + 1 < insn_cnt) + init_explored_state(env, t + 1); + } else { + /* conditional jump with two edges */ + init_explored_state(env, t); + ret = push_insn(t, t + 1, FALLTHROUGH, env, true); + if (ret == 1) + goto peek_stack; + else if (ret < 0) + goto err_free; + + ret = push_insn(t, t + insns[t].off + 1, BRANCH, env, true); + if (ret == 1) + goto peek_stack; + else if (ret < 0) + goto err_free; + } + } else { + /* all other non-branch instructions with single + * fall-through edge + */ + ret = push_insn(t, t + 1, FALLTHROUGH, env, false); + if (ret == 1) + goto peek_stack; + else if (ret < 0) + goto err_free; + } + +mark_explored: + insn_state[t] = EXPLORED; + if (env->cfg.cur_stack-- <= 0) { + verbose(env, "pop stack internal bug\n"); + ret = -EFAULT; + goto err_free; + } + goto peek_stack; + +check_state: + for (i = 0; i < insn_cnt; i++) { + if (insn_state[i] != EXPLORED) { + verbose(env, "unreachable insn %d\n", i); + ret = -EINVAL; + goto err_free; + } + } + 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, + union bpf_attr __user *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; + void __user *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 = u64_to_user_ptr(attr->func_info); + 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 (put_user(min_size, &uattr->func_info_rec_size)) + ret = -EFAULT; + } + goto err_free; + } + + if (copy_from_user(&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_type_is_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; + 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 (offsetof(struct bpf_line_info, line_col) + \ + sizeof(((struct bpf_line_info *)(0))->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, + union bpf_attr __user *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; + void __user *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 = u64_to_user_ptr(attr->line_info); + 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 (put_user(expected_size, + &uattr->line_info_rec_size)) + err = -EFAULT; + } + goto err_free; + } + + if (copy_from_user(&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; + 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; +} + +static int check_btf_info(struct bpf_verifier_env *env, + const union bpf_attr *attr, + union bpf_attr __user *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); + 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; + + 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_id_pair *idmap) +{ + unsigned int i; + + for (i = 0; i < BPF_ID_MAP_SIZE; i++) { + if (!idmap[i].old) { + /* Reached an empty slot; haven't seen this id before */ + idmap[i].old = old_id; + idmap[i].cur = cur_id; + return true; + } + if (idmap[i].old == old_id) + return idmap[i].cur == cur_id; + } + /* We ran out of idmap slots, which should be impossible */ + WARN_ON_ONCE(1); + return false; +} + +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 markes 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; + int i; + + sl = *explored_state(env, insn); + while (sl) { + if (sl->state.branches) + goto next; + if (sl->state.insn_idx != insn || + sl->state.curframe != cur->curframe) + goto next; + for (i = 0; i <= cur->curframe; i++) + if (sl->state.frame[i]->callsite != cur->frame[i]->callsite) + goto next; + clean_verifier_state(env, &sl->state); +next: + sl = sl->next; + } +} + +/* 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_id_pair *idmap) +{ + bool equal; + + if (!(rold->live & REG_LIVE_READ)) + /* explored state didn't use this */ + return true; + + equal = memcmp(rold, rcur, offsetof(struct bpf_reg_state, parent)) == 0; + + if (rold->type == 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 equal && rold->frameno == rcur->frameno; + + if (equal) + return true; + + if (rold->type == NOT_INIT) + /* explored state can't have used this */ + return true; + if (rcur->type == NOT_INIT) + return false; + switch (rold->type) { + case SCALAR_VALUE: + if (env->explore_alu_limits) + return false; + if (rcur->type == SCALAR_VALUE) { + if (!rold->precise) + return true; + /* new val must satisfy old val knowledge */ + return range_within(rold, rcur) && + tnum_in(rold->var_off, rcur->var_off); + } else { + /* We're trying to use a pointer in place of a scalar. + * Even if the scalar was unbounded, 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. + */ + return false; + } + case PTR_TO_MAP_VALUE: + /* If the new min/max/var_off satisfy the old ones and + * everything else matches, we are OK. + * 'id' is not compared, since it's only used for maps with + * bpf_spin_lock inside map element and in such cases if + * the rest of the prog is valid for one map element then + * it's valid for all map elements regardless of the key + * used in bpf_map_lookup() + */ + return memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)) == 0 && + range_within(rold, rcur) && + tnum_in(rold->var_off, rcur->var_off); + case PTR_TO_MAP_VALUE_OR_NULL: + /* a PTR_TO_MAP_VALUE could be safe to use as a + * PTR_TO_MAP_VALUE_OR_NULL into the same map. + * However, if the old PTR_TO_MAP_VALUE_OR_NULL 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 PTR_TO_MAP_VALUE. + */ + if (rcur->type != PTR_TO_MAP_VALUE_OR_NULL) + return false; + if (memcmp(rold, rcur, offsetof(struct bpf_reg_state, id))) + return false; + /* Check our ids match any regs they're supposed to */ + return check_ids(rold->id, rcur->id, idmap); + case PTR_TO_PACKET_META: + case PTR_TO_PACKET: + if (rcur->type != rold->type) + return false; + /* 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 (rold->id && !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_CTX: + case CONST_PTR_TO_MAP: + case PTR_TO_PACKET_END: + case PTR_TO_FLOW_KEYS: + case PTR_TO_SOCKET: + case PTR_TO_SOCKET_OR_NULL: + case PTR_TO_SOCK_COMMON: + case PTR_TO_SOCK_COMMON_OR_NULL: + case PTR_TO_TCP_SOCK: + case PTR_TO_TCP_SOCK_OR_NULL: + case PTR_TO_XDP_SOCK: + /* Only valid matches are exact, which memcmp() above + * would have accepted + */ + default: + /* Don't know what's going on, just say it's not safe */ + return false; + } + + /* Shouldn't get here; if we do, say it's not safe */ + WARN_ON_ONCE(1); + return false; +} + +static bool stacksafe(struct bpf_verifier_env *env, struct bpf_func_state *old, + struct bpf_func_state *cur, struct bpf_id_pair *idmap) +{ + 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++) { + spi = i / BPF_REG_SIZE; + + if (!(old->stack[spi].spilled_ptr.live & REG_LIVE_READ)) { + 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; + + /* 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; + if (!is_spilled_reg(&old->stack[spi])) + continue; + if (!regsafe(env, &old->stack[spi].spilled_ptr, + &cur->stack[spi].spilled_ptr, idmap)) + /* 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 + */ + return false; + } + return true; +} + +static bool refsafe(struct bpf_func_state *old, struct bpf_func_state *cur) +{ + if (old->acquired_refs != cur->acquired_refs) + return false; + return !memcmp(old->refs, cur->refs, + sizeof(*old->refs) * old->acquired_refs); +} + +/* 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) +{ + int i; + + memset(env->idmap_scratch, 0, sizeof(env->idmap_scratch)); + for (i = 0; i < MAX_BPF_REG; i++) + if (!regsafe(env, &old->regs[i], &cur->regs[i], + env->idmap_scratch)) + return false; + + if (!stacksafe(env, old, cur, env->idmap_scratch)) + return false; + + if (!refsafe(old, cur)) + return false; + + return true; +} + +static bool states_equal(struct bpf_verifier_env *env, + struct bpf_verifier_state *old, + struct bpf_verifier_state *cur) +{ + int i; + + if (old->curframe != cur->curframe) + return false; + + /* Verification state from speculative execution simulation + * must never prune a non-speculative execution one. + */ + if (old->speculative && !cur->speculative) + return false; + + if (old->active_spin_lock != cur->active_spin_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])) + 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; + + for (fr = old->curframe; fr >= 0; fr--) { + state = old->frame[fr]; + state_reg = state->regs; + 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) + verbose(env, "frame %d: propagating r%d\n", fr, i); + err = mark_chain_precision_frame(env, fr, i); + if (err < 0) + return err; + } + + 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) + verbose(env, "frame %d: propagating fp%d\n", + fr, (-i - 1) * BPF_REG_SIZE); + err = mark_chain_precision_stack_frame(env, fr, i); + 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 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; + int i, j, err, states_cnt = 0; + bool add_new_state = env->test_state_freq ? true : false; + + cur->last_insn_idx = env->prev_insn_idx; + if (!env->insn_aux_data[insn_idx].prune_point) + /* this 'insn_idx' instruction wasn't marked, so we will not + * be doing state search here + */ + return 0; + + /* 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) { + if (states_maybe_looping(&sl->state, cur) && + states_equal(env, &sl->state, cur)) { + verbose_linfo(env, insn_idx, "; "); + verbose(env, "infinite loop detected at insn %d\n", insn_idx); + 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. + */ + if (env->jmps_processed - env->prev_jmps_processed < 20 && + env->insn_processed - env->prev_insn_processed < 100) + add_new_state = false; + goto miss; + } + if (states_equal(env, &sl->state, cur)) { + 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. + */ + if (sl->miss_cnt > sl->hit_cnt * 3 + 3) { + /* 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) { + 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 push_jmp_history(env, cur); + + if (!add_new_state) + return push_jmp_history(env, cur); + + /* 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; + 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 (type) { + case PTR_TO_CTX: + case PTR_TO_SOCKET: + case PTR_TO_SOCKET_OR_NULL: + case PTR_TO_SOCK_COMMON: + case PTR_TO_SOCK_COMMON_OR_NULL: + case PTR_TO_TCP_SOCK: + case PTR_TO_TCP_SOCK_OR_NULL: + case PTR_TO_XDP_SOCK: + case PTR_TO_BTF_ID: + case PTR_TO_BTF_ID_OR_NULL: + 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 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; + } + + 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 (signal_pending(current)) + return -EAGAIN; + + if (need_resched()) + cond_resched(); + + if (env->log.level & BPF_LOG_LEVEL2 || + (env->log.level & BPF_LOG_LEVEL && do_print_state)) { + if (env->log.level & BPF_LOG_LEVEL2) + verbose(env, "%d:", env->insn_idx); + else + 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]); + do_print_state = false; + } + + if (env->log.level & BPF_LOG_LEVEL) { + const struct bpf_insn_cbs cbs = { + .cb_print = verbose, + .private_data = env, + }; + + verbose_linfo(env, env->insn_idx, "; "); + verbose(env, "%d: ", env->insn_idx); + print_bpf_insn(&cbs, insn, env->allow_ptr_leaks); + } + + if (bpf_prog_is_dev_bound(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 *prev_src_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); + if (err) + return err; + + prev_src_type = &env->insn_aux_data[env->insn_idx].ptr_type; + + if (*prev_src_type == NOT_INIT) { + /* saw a valid insn + * dst_reg = *(u32 *)(src_reg + off) + * save type to validate intersecting paths + */ + *prev_src_type = src_reg_type; + + } else if (reg_type_mismatch(src_reg_type, *prev_src_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. + */ + verbose(env, "same insn cannot be used with different pointers\n"); + return -EINVAL; + } + + } else if (class == BPF_STX) { + enum bpf_reg_type *prev_dst_type, dst_reg_type; + + if (BPF_MODE(insn->code) == BPF_XADD) { + err = check_xadd(env, env->insn_idx, insn); + if (err) + return err; + env->insn_idx++; + continue; + } + + /* 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); + if (err) + return err; + + prev_dst_type = &env->insn_aux_data[env->insn_idx].ptr_type; + + if (*prev_dst_type == NOT_INIT) { + *prev_dst_type = dst_reg_type; + } else if (reg_type_mismatch(dst_reg_type, *prev_dst_type)) { + verbose(env, "same insn cannot be used with different pointers\n"); + return -EINVAL; + } + + } else if (class == BPF_ST) { + 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; + + if (is_ctx_reg(env, insn->dst_reg)) { + verbose(env, "BPF_ST stores into R%d %s is not allowed\n", + insn->dst_reg, + reg_type_str[reg_state(env, insn->dst_reg)->type]); + return -EACCES; + } + + /* 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); + 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->off != 0 || + (insn->src_reg != BPF_REG_0 && + insn->src_reg != BPF_PSEUDO_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_spin_lock && + (insn->src_reg == BPF_PSEUDO_CALL || + insn->imm != BPF_FUNC_spin_unlock)) { + 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 + err = check_helper_call(env, insn->imm, env->insn_idx); + if (err) + return err; + + } else if (opcode == BPF_JA) { + 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_JA uses reserved fields\n"); + return -EINVAL; + } + + env->insn_idx += insn->off + 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_spin_lock) { + verbose(env, "bpf_spin_unlock is missing\n"); + return -EINVAL; + } + + 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_reference_leak(env); + if (err) + return err; + + err = check_return_code(env); + if (err) + return err; +process_bpf_exit: + 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; +} + +/* 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; + const struct btf_type *t; + const char *sym_name; + bool percpu = false; + u32 type, id = insn->imm; + s32 datasec_id; + u64 addr; + int i; + + if (!btf_vmlinux) { + verbose(env, "kernel is missing BTF, make sure CONFIG_DEBUG_INFO_BTF=y is specified in Kconfig.\n"); + return -EINVAL; + } + + if (insn[1].imm != 0) { + verbose(env, "reserved field (insn[1].imm) is used in pseudo_btf_id ldimm64 insn.\n"); + return -EINVAL; + } + + t = btf_type_by_id(btf_vmlinux, id); + if (!t) { + verbose(env, "ldimm64 insn specifies invalid btf_id %d.\n", id); + return -ENOENT; + } + + if (!btf_type_is_var(t)) { + verbose(env, "pseudo btf_id %d in ldimm64 isn't KIND_VAR.\n", + id); + return -EINVAL; + } + + sym_name = btf_name_by_offset(btf_vmlinux, 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); + return -ENOENT; + } + + datasec_id = btf_find_by_name_kind(btf_vmlinux, ".data..percpu", + BTF_KIND_DATASEC); + if (datasec_id > 0) { + datasec = btf_type_by_id(btf_vmlinux, datasec_id); + for_each_vsi(i, datasec, vsi) { + if (vsi->type == id) { + percpu = true; + break; + } + } + } + + insn[0].imm = (u32)addr; + insn[1].imm = addr >> 32; + + type = t->type; + t = btf_type_skip_modifiers(btf_vmlinux, type, NULL); + if (percpu) { + aux->btf_var.reg_type = PTR_TO_PERCPU_BTF_ID; + 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_vmlinux, t, &tsize); + if (IS_ERR(ret)) { + tname = btf_name_by_offset(btf_vmlinux, t->name_off); + verbose(env, "ldimm64 unable to resolve the size of type '%s': %ld\n", + tname, PTR_ERR(ret)); + return -EINVAL; + } + aux->btf_var.reg_type = PTR_TO_MEM; + aux->btf_var.mem_size = tsize; + } else { + aux->btf_var.reg_type = PTR_TO_BTF_ID; + aux->btf_var.btf_id = type; + } + return 0; +} + +static int check_map_prealloc(struct bpf_map *map) +{ + return (map->map_type != BPF_MAP_TYPE_HASH && + map->map_type != BPF_MAP_TYPE_PERCPU_HASH && + map->map_type != BPF_MAP_TYPE_HASH_OF_MAPS) || + !(map->map_flags & BPF_F_NO_PREALLOC); +} + +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: + return true; + default: + return false; + } +} + +static bool is_preallocated_map(struct bpf_map *map) +{ + if (!check_map_prealloc(map)) + return false; + if (map->inner_map_meta && !check_map_prealloc(map->inner_map_meta)) + return false; + return true; +} + +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); + /* + * Validate that trace type programs use preallocated hash maps. + * + * For programs attached to PERF events this is mandatory as the + * perf NMI can hit any arbitrary code sequence. + * + * All other trace types using preallocated hash maps are unsafe as + * well because tracepoint or kprobes can be inside locked regions + * of the memory allocator or at a place where a recursion into the + * memory allocator would see inconsistent state. + * + * On RT enabled kernels run-time allocation of all trace type + * programs is strictly prohibited due to lock type constraints. On + * !RT kernels it is allowed for backwards compatibility reasons for + * now, but warnings are emitted so developers are made aware of + * the unsafety and can fix their programs before this is enforced. + */ + if (is_tracing_prog_type(prog_type) && !is_preallocated_map(map)) { + if (prog_type == BPF_PROG_TYPE_PERF_EVENT) { + verbose(env, "perf_event programs can only use preallocated hash map\n"); + return -EINVAL; + } + if (IS_ENABLED(CONFIG_PREEMPT_RT)) { + verbose(env, "trace type programs can only use preallocated hash map\n"); + return -EINVAL; + } + WARN_ONCE(1, "trace type BPF program uses run-time allocation\n"); + verbose(env, "trace type programs with run-time allocated hash maps are unsafe. Switch to preallocated hash maps.\n"); + } + + if ((is_tracing_prog_type(prog_type) || + prog_type == BPF_PROG_TYPE_SOCKET_FILTER) && + map_value_has_spin_lock(map)) { + verbose(env, "tracing progs cannot use bpf_spin_lock yet\n"); + return -EINVAL; + } + + if ((bpf_prog_is_dev_bound(prog->aux) || bpf_map_is_dev_bound(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: + if (!is_preallocated_map(map)) { + verbose(env, + "Sleepable programs can only use preallocated hash maps\n"); + return -EINVAL; + } + break; + default: + verbose(env, + "Sleepable programs can only use array and hash 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 || insn->imm != 0)) { + verbose(env, "BPF_LDX uses reserved fields\n"); + return -EINVAL; + } + + if (BPF_CLASS(insn->code) == BPF_STX && + ((BPF_MODE(insn->code) != BPF_MEM && + BPF_MODE(insn->code) != BPF_XADD) || insn->imm != 0)) { + verbose(env, "BPF_STX 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; + + 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; + } + + /* In final convert_pseudo_ld_imm64() step, this is + * converted into regular 64-bit imm load insn. + */ + if ((insn[0].src_reg != BPF_PSEUDO_MAP_FD && + insn[0].src_reg != BPF_PSEUDO_MAP_VALUE) || + (insn[0].src_reg == BPF_PSEUDO_MAP_FD && + insn[1].imm != 0)) { + verbose(env, + "unrecognized bpf_ld_imm64 insn\n"); + return -EINVAL; + } + + f = fdget(insn[0].imm); + 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->src_reg == BPF_PSEUDO_MAP_FD) { + 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); +} + +/* 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)) + 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_dev_bound(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; + + if (BPF_CLASS(code) == BPF_JMP32) + return true; + + if (BPF_CLASS(code) != BPF_JMP) + return false; + + op = BPF_OP(code); + 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_dev_bound(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; + + insn = insns[adj_idx]; + if (!aux[adj_idx].zext_dst) { + u8 code, class; + u32 imm_rnd; + + if (!rnd_hi32) + continue; + + code = insn.code; + class = BPF_CLASS(code); + if (insn_no_def(&insn)) + continue; + + /* NOTE: arg "reg" (the fourth one) is only used for + * BPF_STX which has been ruled out in above + * check, it is safe to pass NULL here. + */ + if (is_reg64(env, &insn, insn.dst_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_int(); + rnd_hi32_patch[0] = insn; + rnd_hi32_patch[1].imm = imm_rnd; + rnd_hi32_patch[3].dst_reg = insn.dst_reg; + patch = rnd_hi32_patch; + patch_len = 4; + goto apply_patch_buffer; + } + + if (!bpf_jit_needs_zext()) + continue; + + zext_patch[0] = insn; + zext_patch[1].dst_reg = insn.dst_reg; + zext_patch[1].src_reg = insn.dst_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_dev_bound(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; + bool ctx_access; + + 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)) { + type = BPF_READ; + ctx_access = true; + } 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; + ctx_access = BPF_CLASS(insn->code) == BPF_STX; + } 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; + } + + if (!ctx_access) + continue; + + switch (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: + if (type == BPF_READ) { + insn->code = BPF_LDX | BPF_PROBE_MEM | + BPF_SIZE((insn)->code); + env->prog->aux->num_exentries++; + } else if (resolve_prog_type(env->prog) != BPF_PROG_TYPE_STRUCT_OPS) { + verbose(env, "Writes through BTF pointers are not allowed\n"); + return -EINVAL; + } + continue; + default: + continue; + } + + ctx_field_size = env->insn_aux_data[i + delta].ctx_field_size; + size = BPF_LDST_BYTES(insn); + + /* 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); + } + } + + 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 (insn->code != (BPF_JMP | BPF_CALL) || + insn->src_reg != BPF_PSEUDO_CALL) + 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; + } + + 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]->aux->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]->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) + 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 (insn->code != (BPF_JMP | BPF_CALL) || + insn->src_reg != BPF_PSEUDO_CALL) + continue; + subprog = insn->off; + insn->imm = BPF_CAST_CALL(func[subprog]->bpf_func) - + __bpf_call_base; + } + + /* 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 + */ + for (i = 0; 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 (insn->code != (BPF_JMP | BPF_CALL) || + insn->src_reg != BPF_PSEUDO_CALL) + 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->aux->func = func; + prog->aux->func_cnt = env->subprog_cnt; + bpf_prog_free_unused_jited_linfo(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; + for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) { + if (insn->code != (BPF_JMP | BPF_CALL) || + insn->src_reg != BPF_PSEUDO_CALL) + continue; + insn->off = 0; + insn->imm = env->insn_aux_data[i].call_imm; + } + bpf_prog_free_jited_linfo(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; + int i, depth; +#endif + int err = 0; + + if (env->prog->jit_requested && + !bpf_prog_is_dev_bound(env->prog->aux)) { + err = jit_subprogs(env); + if (err == 0) + return 0; + if (err == -EFAULT) + return err; + } +#ifndef CONFIG_BPF_JIT_ALWAYS_ON + 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 (insn->code != (BPF_JMP | BPF_CALL) || + insn->src_reg != BPF_PSEUDO_CALL) + 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; +} + +/* fixup insn->imm field of bpf_call instructions + * and inline eligible helpers as explicit sequence of BPF instructions + * + * this function is called after eBPF program passed verification + */ +static int fixup_bpf_calls(struct bpf_verifier_env *env) +{ + struct bpf_prog *prog = env->prog; + bool expect_blinding = bpf_jit_blinding_enabled(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++) { + 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; + } + + 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; + } + + 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 insn_buf[16]; + 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->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 interpeter 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 && !expect_blinding && + 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; + } + + /* 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)) { + 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, + (int (*)(struct bpf_map *map, void *key))NULL)); + BUILD_BUG_ON(!__same_type(ops->map_update_elem, + (int (*)(struct bpf_map *map, void *key, void *value, + u64 flags))NULL)); + BUILD_BUG_ON(!__same_type(ops->map_push_elem, + (int (*)(struct bpf_map *map, void *value, + u64 flags))NULL)); + BUILD_BUG_ON(!__same_type(ops->map_pop_elem, + (int (*)(struct bpf_map *map, void *value))NULL)); + BUILD_BUG_ON(!__same_type(ops->map_peek_elem, + (int (*)(struct bpf_map *map, void *value))NULL)); +patch_map_ops_generic: + switch (insn->imm) { + case BPF_FUNC_map_lookup_elem: + insn->imm = BPF_CAST_CALL(ops->map_lookup_elem) - + __bpf_call_base; + continue; + case BPF_FUNC_map_update_elem: + insn->imm = BPF_CAST_CALL(ops->map_update_elem) - + __bpf_call_base; + continue; + case BPF_FUNC_map_delete_elem: + insn->imm = BPF_CAST_CALL(ops->map_delete_elem) - + __bpf_call_base; + continue; + case BPF_FUNC_map_push_elem: + insn->imm = BPF_CAST_CALL(ops->map_push_elem) - + __bpf_call_base; + continue; + case BPF_FUNC_map_pop_elem: + insn->imm = BPF_CAST_CALL(ops->map_pop_elem) - + __bpf_call_base; + continue; + case BPF_FUNC_map_peek_elem: + insn->imm = BPF_CAST_CALL(ops->map_peek_elem) - + __bpf_call_base; + continue; + } + + goto patch_call_imm; + } + + 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; + } + +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; + } + } + + 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 { + /* 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_func_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); + + 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; +} + +/* non exhaustive list of sleepable bpf_lsm_*() functions */ +BTF_SET_START(btf_sleepable_lsm_hooks) +#ifdef CONFIG_BPF_LSM +BTF_ID(func, bpf_lsm_bprm_committed_creds) +#else +BTF_ID_UNUSED +#endif +BTF_SET_END(btf_sleepable_lsm_hooks) + +static int check_sleepable_lsm_hook(u32 btf_id) +{ + return btf_id_set_contains(&btf_sleepable_lsm_hooks, btf_id); +} + +/* 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, __add_to_page_cache_locked) +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; + + if (!btf_id) { + bpf_log(log, "Tracing programs must provide btf_id\n"); + return -EINVAL; + } + btf = tgt_prog ? tgt_prog->aux->btf : btf_vmlinux; + 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; + + 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_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 { + addr = kallsyms_lookup_name(tname); + if (!addr) { + 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 only 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; + break; + case BPF_PROG_TYPE_LSM: + /* LSM progs check that they are attached to bpf_lsm_*() funcs. + * Only some of them are sleepable. + */ + if (check_sleepable_lsm_hook(btf_id)) + ret = 0; + break; + default: + break; + } + if (ret) { + bpf_log(log, "%s is not sleepable\n", tname); + return ret; + } + } else if (prog->expected_attach_type == BPF_MODIFY_RETURN) { + if (tgt_prog) { + bpf_log(log, "can't modify return codes of BPF programs\n"); + return -EINVAL; + } + ret = check_attach_modify_return(addr, tname); + if (ret) { + 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; + return 0; +} + +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->aux->sleepable && prog->type != BPF_PROG_TYPE_TRACING && + prog->type != BPF_PROG_TYPE_LSM) { + verbose(env, "Only fentry/fexit/fmod_ret and lsm 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; + + 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; + } + + key = bpf_trampoline_compute_key(tgt_prog, btf_id); + tr = bpf_trampoline_get(key, &tgt_info); + if (!tr) + return -ENOMEM; + + 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, + union bpf_attr __user *uattr) +{ + u64 start_time = ktime_get_ns(); + struct bpf_verifier_env *env; + struct bpf_verifier_log *log; + int i, len, ret = -EINVAL; + 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; + log = &env->log; + + 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]; + 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); + + if (attr->log_level || attr->log_buf || attr->log_size) { + /* user requested verbose verifier output + * and supplied buffer to store the verification trace + */ + log->level = attr->log_level; + log->ubuf = (char __user *) (unsigned long) attr->log_buf; + log->len_total = attr->log_size; + + /* log attributes have to be sane */ + if (!bpf_verifier_log_attr_valid(log)) { + ret = -EINVAL; + goto err_unlock; + } + } + + 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->allow_ptr_to_map_access = bpf_allow_ptr_to_map_access(); + 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 = 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_dev_bound(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_dev_bound(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 (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 = fixup_bpf_calls(env); + + /* do 32-bit optimization after insn patching has done so those patched + * insns could be handled correctly. + */ + if (ret == 0 && !bpf_prog_is_dev_bound(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); + + if (log->level && bpf_verifier_log_full(log)) + ret = -ENOSPC; + if (log->level && !log->ubuf) { + ret = -EFAULT; + goto err_release_maps; + } + + if (ret == 0 && 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; + + /* program is valid. Convert pseudo bpf_ld_imm64 into generic + * bpf_ld_imm64 instructions + */ + convert_pseudo_ld_imm64(env); + } + + if (ret == 0) + 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); + + /* 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; +} |