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Diffstat (limited to 'include/linux/btf.h')
-rw-r--r-- | include/linux/btf.h | 574 |
1 files changed, 574 insertions, 0 deletions
diff --git a/include/linux/btf.h b/include/linux/btf.h new file mode 100644 index 000000000..928113a80 --- /dev/null +++ b/include/linux/btf.h @@ -0,0 +1,574 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (c) 2018 Facebook */ + +#ifndef _LINUX_BTF_H +#define _LINUX_BTF_H 1 + +#include <linux/types.h> +#include <linux/bpfptr.h> +#include <linux/bsearch.h> +#include <linux/btf_ids.h> +#include <uapi/linux/btf.h> +#include <uapi/linux/bpf.h> + +#define BTF_TYPE_EMIT(type) ((void)(type *)0) +#define BTF_TYPE_EMIT_ENUM(enum_val) ((void)enum_val) + +/* These need to be macros, as the expressions are used in assembler input */ +#define KF_ACQUIRE (1 << 0) /* kfunc is an acquire function */ +#define KF_RELEASE (1 << 1) /* kfunc is a release function */ +#define KF_RET_NULL (1 << 2) /* kfunc returns a pointer that may be NULL */ +/* Trusted arguments are those which are guaranteed to be valid when passed to + * the kfunc. It is used to enforce that pointers obtained from either acquire + * kfuncs, or from the main kernel on a tracepoint or struct_ops callback + * invocation, remain unmodified when being passed to helpers taking trusted + * args. + * + * Consider, for example, the following new task tracepoint: + * + * SEC("tp_btf/task_newtask") + * int BPF_PROG(new_task_tp, struct task_struct *task, u64 clone_flags) + * { + * ... + * } + * + * And the following kfunc: + * + * BTF_ID_FLAGS(func, bpf_task_acquire, KF_ACQUIRE | KF_TRUSTED_ARGS) + * + * All invocations to the kfunc must pass the unmodified, unwalked task: + * + * bpf_task_acquire(task); // Allowed + * bpf_task_acquire(task->last_wakee); // Rejected, walked task + * + * Programs may also pass referenced tasks directly to the kfunc: + * + * struct task_struct *acquired; + * + * acquired = bpf_task_acquire(task); // Allowed, same as above + * bpf_task_acquire(acquired); // Allowed + * bpf_task_acquire(task); // Allowed + * bpf_task_acquire(acquired->last_wakee); // Rejected, walked task + * + * Programs may _not_, however, pass a task from an arbitrary fentry/fexit, or + * kprobe/kretprobe to the kfunc, as BPF cannot guarantee that all of these + * pointers are guaranteed to be safe. For example, the following BPF program + * would be rejected: + * + * SEC("kretprobe/free_task") + * int BPF_PROG(free_task_probe, struct task_struct *tsk) + * { + * struct task_struct *acquired; + * + * acquired = bpf_task_acquire(acquired); // Rejected, not a trusted pointer + * bpf_task_release(acquired); + * + * return 0; + * } + */ +#define KF_TRUSTED_ARGS (1 << 4) /* kfunc only takes trusted pointer arguments */ +#define KF_SLEEPABLE (1 << 5) /* kfunc may sleep */ +#define KF_DESTRUCTIVE (1 << 6) /* kfunc performs destructive actions */ +#define KF_RCU (1 << 7) /* kfunc takes either rcu or trusted pointer arguments */ +/* only one of KF_ITER_{NEW,NEXT,DESTROY} could be specified per kfunc */ +#define KF_ITER_NEW (1 << 8) /* kfunc implements BPF iter constructor */ +#define KF_ITER_NEXT (1 << 9) /* kfunc implements BPF iter next method */ +#define KF_ITER_DESTROY (1 << 10) /* kfunc implements BPF iter destructor */ + +/* + * Tag marking a kernel function as a kfunc. This is meant to minimize the + * amount of copy-paste that kfunc authors have to include for correctness so + * as to avoid issues such as the compiler inlining or eliding either a static + * kfunc, or a global kfunc in an LTO build. + */ +#define __bpf_kfunc __used noinline + +/* + * Return the name of the passed struct, if exists, or halt the build if for + * example the structure gets renamed. In this way, developers have to revisit + * the code using that structure name, and update it accordingly. + */ +#define stringify_struct(x) \ + ({ BUILD_BUG_ON(sizeof(struct x) < 0); \ + __stringify(x); }) + +struct btf; +struct btf_member; +struct btf_type; +union bpf_attr; +struct btf_show; +struct btf_id_set; +struct bpf_prog; + +typedef int (*btf_kfunc_filter_t)(const struct bpf_prog *prog, u32 kfunc_id); + +struct btf_kfunc_id_set { + struct module *owner; + struct btf_id_set8 *set; + btf_kfunc_filter_t filter; +}; + +struct btf_id_dtor_kfunc { + u32 btf_id; + u32 kfunc_btf_id; +}; + +struct btf_struct_meta { + u32 btf_id; + struct btf_record *record; +}; + +struct btf_struct_metas { + u32 cnt; + struct btf_struct_meta types[]; +}; + +extern const struct file_operations btf_fops; + +void btf_get(struct btf *btf); +void btf_put(struct btf *btf); +int btf_new_fd(const union bpf_attr *attr, bpfptr_t uattr, u32 uattr_sz); +struct btf *btf_get_by_fd(int fd); +int btf_get_info_by_fd(const struct btf *btf, + const union bpf_attr *attr, + union bpf_attr __user *uattr); +/* Figure out the size of a type_id. If type_id is a modifier + * (e.g. const), it will be resolved to find out the type with size. + * + * For example: + * In describing "const void *", type_id is "const" and "const" + * refers to "void *". The return type will be "void *". + * + * If type_id is a simple "int", then return type will be "int". + * + * @btf: struct btf object + * @type_id: Find out the size of type_id. The type_id of the return + * type is set to *type_id. + * @ret_size: It can be NULL. If not NULL, the size of the return + * type is set to *ret_size. + * Return: The btf_type (resolved to another type with size info if needed). + * NULL is returned if type_id itself does not have size info + * (e.g. void) or it cannot be resolved to another type that + * has size info. + * *type_id and *ret_size will not be changed in the + * NULL return case. + */ +const struct btf_type *btf_type_id_size(const struct btf *btf, + u32 *type_id, + u32 *ret_size); + +/* + * Options to control show behaviour. + * - BTF_SHOW_COMPACT: no formatting around type information + * - BTF_SHOW_NONAME: no struct/union member names/types + * - BTF_SHOW_PTR_RAW: show raw (unobfuscated) pointer values; + * equivalent to %px. + * - BTF_SHOW_ZERO: show zero-valued struct/union members; they + * are not displayed by default + * - BTF_SHOW_UNSAFE: skip use of bpf_probe_read() to safely read + * data before displaying it. + */ +#define BTF_SHOW_COMPACT BTF_F_COMPACT +#define BTF_SHOW_NONAME BTF_F_NONAME +#define BTF_SHOW_PTR_RAW BTF_F_PTR_RAW +#define BTF_SHOW_ZERO BTF_F_ZERO +#define BTF_SHOW_UNSAFE (1ULL << 4) + +void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj, + struct seq_file *m); +int btf_type_seq_show_flags(const struct btf *btf, u32 type_id, void *obj, + struct seq_file *m, u64 flags); + +/* + * Copy len bytes of string representation of obj of BTF type_id into buf. + * + * @btf: struct btf object + * @type_id: type id of type obj points to + * @obj: pointer to typed data + * @buf: buffer to write to + * @len: maximum length to write to buf + * @flags: show options (see above) + * + * Return: length that would have been/was copied as per snprintf, or + * negative error. + */ +int btf_type_snprintf_show(const struct btf *btf, u32 type_id, void *obj, + char *buf, int len, u64 flags); + +int btf_get_fd_by_id(u32 id); +u32 btf_obj_id(const struct btf *btf); +bool btf_is_kernel(const struct btf *btf); +bool btf_is_module(const struct btf *btf); +struct module *btf_try_get_module(const struct btf *btf); +u32 btf_nr_types(const struct btf *btf); +bool btf_member_is_reg_int(const struct btf *btf, const struct btf_type *s, + const struct btf_member *m, + u32 expected_offset, u32 expected_size); +struct btf_record *btf_parse_fields(const struct btf *btf, const struct btf_type *t, + u32 field_mask, u32 value_size); +int btf_check_and_fixup_fields(const struct btf *btf, struct btf_record *rec); +bool btf_type_is_void(const struct btf_type *t); +s32 btf_find_by_name_kind(const struct btf *btf, const char *name, u8 kind); +s32 bpf_find_btf_id(const char *name, u32 kind, struct btf **btf_p); +const struct btf_type *btf_type_skip_modifiers(const struct btf *btf, + u32 id, u32 *res_id); +const struct btf_type *btf_type_resolve_ptr(const struct btf *btf, + u32 id, u32 *res_id); +const struct btf_type *btf_type_resolve_func_ptr(const struct btf *btf, + u32 id, u32 *res_id); +const struct btf_type * +btf_resolve_size(const struct btf *btf, const struct btf_type *type, + u32 *type_size); +const char *btf_type_str(const struct btf_type *t); + +#define for_each_member(i, struct_type, member) \ + for (i = 0, member = btf_type_member(struct_type); \ + i < btf_type_vlen(struct_type); \ + i++, member++) + +#define for_each_vsi(i, datasec_type, member) \ + for (i = 0, member = btf_type_var_secinfo(datasec_type); \ + i < btf_type_vlen(datasec_type); \ + i++, member++) + +static inline bool btf_type_is_ptr(const struct btf_type *t) +{ + return BTF_INFO_KIND(t->info) == BTF_KIND_PTR; +} + +static inline bool btf_type_is_int(const struct btf_type *t) +{ + return BTF_INFO_KIND(t->info) == BTF_KIND_INT; +} + +static inline bool btf_type_is_small_int(const struct btf_type *t) +{ + return btf_type_is_int(t) && t->size <= sizeof(u64); +} + +static inline u8 btf_int_encoding(const struct btf_type *t) +{ + return BTF_INT_ENCODING(*(u32 *)(t + 1)); +} + +static inline bool btf_type_is_signed_int(const struct btf_type *t) +{ + return btf_type_is_int(t) && (btf_int_encoding(t) & BTF_INT_SIGNED); +} + +static inline bool btf_type_is_enum(const struct btf_type *t) +{ + return BTF_INFO_KIND(t->info) == BTF_KIND_ENUM; +} + +static inline bool btf_is_any_enum(const struct btf_type *t) +{ + return BTF_INFO_KIND(t->info) == BTF_KIND_ENUM || + BTF_INFO_KIND(t->info) == BTF_KIND_ENUM64; +} + +static inline bool btf_kind_core_compat(const struct btf_type *t1, + const struct btf_type *t2) +{ + return BTF_INFO_KIND(t1->info) == BTF_INFO_KIND(t2->info) || + (btf_is_any_enum(t1) && btf_is_any_enum(t2)); +} + +static inline bool str_is_empty(const char *s) +{ + return !s || !s[0]; +} + +static inline u16 btf_kind(const struct btf_type *t) +{ + return BTF_INFO_KIND(t->info); +} + +static inline bool btf_is_enum(const struct btf_type *t) +{ + return btf_kind(t) == BTF_KIND_ENUM; +} + +static inline bool btf_is_enum64(const struct btf_type *t) +{ + return btf_kind(t) == BTF_KIND_ENUM64; +} + +static inline u64 btf_enum64_value(const struct btf_enum64 *e) +{ + return ((u64)e->val_hi32 << 32) | e->val_lo32; +} + +static inline bool btf_is_composite(const struct btf_type *t) +{ + u16 kind = btf_kind(t); + + return kind == BTF_KIND_STRUCT || kind == BTF_KIND_UNION; +} + +static inline bool btf_is_array(const struct btf_type *t) +{ + return btf_kind(t) == BTF_KIND_ARRAY; +} + +static inline bool btf_is_int(const struct btf_type *t) +{ + return btf_kind(t) == BTF_KIND_INT; +} + +static inline bool btf_is_ptr(const struct btf_type *t) +{ + return btf_kind(t) == BTF_KIND_PTR; +} + +static inline u8 btf_int_offset(const struct btf_type *t) +{ + return BTF_INT_OFFSET(*(u32 *)(t + 1)); +} + +static inline bool btf_type_is_scalar(const struct btf_type *t) +{ + return btf_type_is_int(t) || btf_type_is_enum(t); +} + +static inline bool btf_type_is_typedef(const struct btf_type *t) +{ + return BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF; +} + +static inline bool btf_type_is_volatile(const struct btf_type *t) +{ + return BTF_INFO_KIND(t->info) == BTF_KIND_VOLATILE; +} + +static inline bool btf_type_is_func(const struct btf_type *t) +{ + return BTF_INFO_KIND(t->info) == BTF_KIND_FUNC; +} + +static inline bool btf_type_is_func_proto(const struct btf_type *t) +{ + return BTF_INFO_KIND(t->info) == BTF_KIND_FUNC_PROTO; +} + +static inline bool btf_type_is_var(const struct btf_type *t) +{ + return BTF_INFO_KIND(t->info) == BTF_KIND_VAR; +} + +static inline bool btf_type_is_type_tag(const struct btf_type *t) +{ + return BTF_INFO_KIND(t->info) == BTF_KIND_TYPE_TAG; +} + +/* union is only a special case of struct: + * all its offsetof(member) == 0 + */ +static inline bool btf_type_is_struct(const struct btf_type *t) +{ + u8 kind = BTF_INFO_KIND(t->info); + + return kind == BTF_KIND_STRUCT || kind == BTF_KIND_UNION; +} + +static inline bool __btf_type_is_struct(const struct btf_type *t) +{ + return BTF_INFO_KIND(t->info) == BTF_KIND_STRUCT; +} + +static inline bool btf_type_is_array(const struct btf_type *t) +{ + return BTF_INFO_KIND(t->info) == BTF_KIND_ARRAY; +} + +static inline u16 btf_type_vlen(const struct btf_type *t) +{ + return BTF_INFO_VLEN(t->info); +} + +static inline u16 btf_vlen(const struct btf_type *t) +{ + return btf_type_vlen(t); +} + +static inline u16 btf_func_linkage(const struct btf_type *t) +{ + return BTF_INFO_VLEN(t->info); +} + +static inline bool btf_type_kflag(const struct btf_type *t) +{ + return BTF_INFO_KFLAG(t->info); +} + +static inline u32 __btf_member_bit_offset(const struct btf_type *struct_type, + const struct btf_member *member) +{ + return btf_type_kflag(struct_type) ? BTF_MEMBER_BIT_OFFSET(member->offset) + : member->offset; +} + +static inline u32 __btf_member_bitfield_size(const struct btf_type *struct_type, + const struct btf_member *member) +{ + return btf_type_kflag(struct_type) ? BTF_MEMBER_BITFIELD_SIZE(member->offset) + : 0; +} + +static inline struct btf_member *btf_members(const struct btf_type *t) +{ + return (struct btf_member *)(t + 1); +} + +static inline u32 btf_member_bit_offset(const struct btf_type *t, u32 member_idx) +{ + const struct btf_member *m = btf_members(t) + member_idx; + + return __btf_member_bit_offset(t, m); +} + +static inline u32 btf_member_bitfield_size(const struct btf_type *t, u32 member_idx) +{ + const struct btf_member *m = btf_members(t) + member_idx; + + return __btf_member_bitfield_size(t, m); +} + +static inline const struct btf_member *btf_type_member(const struct btf_type *t) +{ + return (const struct btf_member *)(t + 1); +} + +static inline struct btf_array *btf_array(const struct btf_type *t) +{ + return (struct btf_array *)(t + 1); +} + +static inline struct btf_enum *btf_enum(const struct btf_type *t) +{ + return (struct btf_enum *)(t + 1); +} + +static inline struct btf_enum64 *btf_enum64(const struct btf_type *t) +{ + return (struct btf_enum64 *)(t + 1); +} + +static inline const struct btf_var_secinfo *btf_type_var_secinfo( + const struct btf_type *t) +{ + return (const struct btf_var_secinfo *)(t + 1); +} + +static inline struct btf_param *btf_params(const struct btf_type *t) +{ + return (struct btf_param *)(t + 1); +} + +static inline int btf_id_cmp_func(const void *a, const void *b) +{ + const int *pa = a, *pb = b; + + return *pa - *pb; +} + +static inline bool btf_id_set_contains(const struct btf_id_set *set, u32 id) +{ + return bsearch(&id, set->ids, set->cnt, sizeof(u32), btf_id_cmp_func) != NULL; +} + +static inline void *btf_id_set8_contains(const struct btf_id_set8 *set, u32 id) +{ + return bsearch(&id, set->pairs, set->cnt, sizeof(set->pairs[0]), btf_id_cmp_func); +} + +struct bpf_verifier_log; + +#ifdef CONFIG_BPF_SYSCALL +const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id); +const char *btf_name_by_offset(const struct btf *btf, u32 offset); +struct btf *btf_parse_vmlinux(void); +struct btf *bpf_prog_get_target_btf(const struct bpf_prog *prog); +u32 *btf_kfunc_id_set_contains(const struct btf *btf, u32 kfunc_btf_id, + const struct bpf_prog *prog); +u32 *btf_kfunc_is_modify_return(const struct btf *btf, u32 kfunc_btf_id, + const struct bpf_prog *prog); +int register_btf_kfunc_id_set(enum bpf_prog_type prog_type, + const struct btf_kfunc_id_set *s); +int register_btf_fmodret_id_set(const struct btf_kfunc_id_set *kset); +s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id); +int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_cnt, + struct module *owner); +struct btf_struct_meta *btf_find_struct_meta(const struct btf *btf, u32 btf_id); +const struct btf_member * +btf_get_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf, + const struct btf_type *t, enum bpf_prog_type prog_type, + int arg); +int get_kern_ctx_btf_id(struct bpf_verifier_log *log, enum bpf_prog_type prog_type); +bool btf_types_are_same(const struct btf *btf1, u32 id1, + const struct btf *btf2, u32 id2); +#else +static inline const struct btf_type *btf_type_by_id(const struct btf *btf, + u32 type_id) +{ + return NULL; +} +static inline const char *btf_name_by_offset(const struct btf *btf, + u32 offset) +{ + return NULL; +} +static inline u32 *btf_kfunc_id_set_contains(const struct btf *btf, + u32 kfunc_btf_id, + struct bpf_prog *prog) + +{ + return NULL; +} +static inline int register_btf_kfunc_id_set(enum bpf_prog_type prog_type, + const struct btf_kfunc_id_set *s) +{ + return 0; +} +static inline s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id) +{ + return -ENOENT; +} +static inline int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, + u32 add_cnt, struct module *owner) +{ + return 0; +} +static inline struct btf_struct_meta *btf_find_struct_meta(const struct btf *btf, u32 btf_id) +{ + return NULL; +} +static inline const struct btf_member * +btf_get_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf, + const struct btf_type *t, enum bpf_prog_type prog_type, + int arg) +{ + return NULL; +} +static inline int get_kern_ctx_btf_id(struct bpf_verifier_log *log, + enum bpf_prog_type prog_type) { + return -EINVAL; +} +static inline bool btf_types_are_same(const struct btf *btf1, u32 id1, + const struct btf *btf2, u32 id2) +{ + return false; +} +#endif + +static inline bool btf_type_is_struct_ptr(struct btf *btf, const struct btf_type *t) +{ + if (!btf_type_is_ptr(t)) + return false; + + t = btf_type_skip_modifiers(btf, t->type, NULL); + + return btf_type_is_struct(t); +} + +#endif |