1 /* SPDX-License-Identifier: GPL-2.0 */
2 /* Copyright (c) 2018 Facebook */
7 #include <linux/types.h>
8 #include <linux/bpfptr.h>
9 #include <linux/bsearch.h>
10 #include <linux/btf_ids.h>
11 #include <uapi/linux/btf.h>
12 #include <uapi/linux/bpf.h>
14 #define BTF_TYPE_EMIT(type) ((void)(type *)0)
15 #define BTF_TYPE_EMIT_ENUM(enum_val) ((void)enum_val)
17 /* These need to be macros, as the expressions are used in assembler input */
18 #define KF_ACQUIRE (1 << 0) /* kfunc is an acquire function */
19 #define KF_RELEASE (1 << 1) /* kfunc is a release function */
20 #define KF_RET_NULL (1 << 2) /* kfunc returns a pointer that may be NULL */
21 /* Trusted arguments are those which are guaranteed to be valid when passed to
22 * the kfunc. It is used to enforce that pointers obtained from either acquire
23 * kfuncs, or from the main kernel on a tracepoint or struct_ops callback
24 * invocation, remain unmodified when being passed to helpers taking trusted
27 * Consider, for example, the following new task tracepoint:
29 * SEC("tp_btf/task_newtask")
30 * int BPF_PROG(new_task_tp, struct task_struct *task, u64 clone_flags)
35 * And the following kfunc:
37 * BTF_ID_FLAGS(func, bpf_task_acquire, KF_ACQUIRE | KF_TRUSTED_ARGS)
39 * All invocations to the kfunc must pass the unmodified, unwalked task:
41 * bpf_task_acquire(task); // Allowed
42 * bpf_task_acquire(task->last_wakee); // Rejected, walked task
44 * Programs may also pass referenced tasks directly to the kfunc:
46 * struct task_struct *acquired;
48 * acquired = bpf_task_acquire(task); // Allowed, same as above
49 * bpf_task_acquire(acquired); // Allowed
50 * bpf_task_acquire(task); // Allowed
51 * bpf_task_acquire(acquired->last_wakee); // Rejected, walked task
53 * Programs may _not_, however, pass a task from an arbitrary fentry/fexit, or
54 * kprobe/kretprobe to the kfunc, as BPF cannot guarantee that all of these
55 * pointers are guaranteed to be safe. For example, the following BPF program
58 * SEC("kretprobe/free_task")
59 * int BPF_PROG(free_task_probe, struct task_struct *tsk)
61 * struct task_struct *acquired;
63 * acquired = bpf_task_acquire(acquired); // Rejected, not a trusted pointer
64 * bpf_task_release(acquired);
69 #define KF_TRUSTED_ARGS (1 << 4) /* kfunc only takes trusted pointer arguments */
70 #define KF_SLEEPABLE (1 << 5) /* kfunc may sleep */
71 #define KF_DESTRUCTIVE (1 << 6) /* kfunc performs destructive actions */
72 #define KF_RCU (1 << 7) /* kfunc takes either rcu or trusted pointer arguments */
73 /* only one of KF_ITER_{NEW,NEXT,DESTROY} could be specified per kfunc */
74 #define KF_ITER_NEW (1 << 8) /* kfunc implements BPF iter constructor */
75 #define KF_ITER_NEXT (1 << 9) /* kfunc implements BPF iter next method */
76 #define KF_ITER_DESTROY (1 << 10) /* kfunc implements BPF iter destructor */
77 #define KF_RCU_PROTECTED (1 << 11) /* kfunc should be protected by rcu cs when they are invoked */
80 * Tag marking a kernel function as a kfunc. This is meant to minimize the
81 * amount of copy-paste that kfunc authors have to include for correctness so
82 * as to avoid issues such as the compiler inlining or eliding either a static
83 * kfunc, or a global kfunc in an LTO build.
85 #define __bpf_kfunc __used noinline
87 #define __bpf_kfunc_start_defs() \
89 __diag_ignore_all("-Wmissing-declarations", \
90 "Global kfuncs as their definitions will be in BTF");\
91 __diag_ignore_all("-Wmissing-prototypes", \
92 "Global kfuncs as their definitions will be in BTF")
94 #define __bpf_kfunc_end_defs() __diag_pop()
95 #define __bpf_hook_start() __bpf_kfunc_start_defs()
96 #define __bpf_hook_end() __bpf_kfunc_end_defs()
99 * Return the name of the passed struct, if exists, or halt the build if for
100 * example the structure gets renamed. In this way, developers have to revisit
101 * the code using that structure name, and update it accordingly.
103 #define stringify_struct(x) \
104 ({ BUILD_BUG_ON(sizeof(struct x) < 0); \
115 typedef int (*btf_kfunc_filter_t)(const struct bpf_prog *prog, u32 kfunc_id);
117 struct btf_kfunc_id_set {
118 struct module *owner;
119 struct btf_id_set8 *set;
120 btf_kfunc_filter_t filter;
123 struct btf_id_dtor_kfunc {
128 struct btf_struct_meta {
130 struct btf_record *record;
133 struct btf_struct_metas {
135 struct btf_struct_meta types[];
138 extern const struct file_operations btf_fops;
140 const char *btf_get_name(const struct btf *btf);
141 void btf_get(struct btf *btf);
142 void btf_put(struct btf *btf);
143 int btf_new_fd(const union bpf_attr *attr, bpfptr_t uattr, u32 uattr_sz);
144 struct btf *btf_get_by_fd(int fd);
145 int btf_get_info_by_fd(const struct btf *btf,
146 const union bpf_attr *attr,
147 union bpf_attr __user *uattr);
148 /* Figure out the size of a type_id. If type_id is a modifier
149 * (e.g. const), it will be resolved to find out the type with size.
152 * In describing "const void *", type_id is "const" and "const"
153 * refers to "void *". The return type will be "void *".
155 * If type_id is a simple "int", then return type will be "int".
157 * @btf: struct btf object
158 * @type_id: Find out the size of type_id. The type_id of the return
159 * type is set to *type_id.
160 * @ret_size: It can be NULL. If not NULL, the size of the return
161 * type is set to *ret_size.
162 * Return: The btf_type (resolved to another type with size info if needed).
163 * NULL is returned if type_id itself does not have size info
164 * (e.g. void) or it cannot be resolved to another type that
166 * *type_id and *ret_size will not be changed in the
169 const struct btf_type *btf_type_id_size(const struct btf *btf,
174 * Options to control show behaviour.
175 * - BTF_SHOW_COMPACT: no formatting around type information
176 * - BTF_SHOW_NONAME: no struct/union member names/types
177 * - BTF_SHOW_PTR_RAW: show raw (unobfuscated) pointer values;
179 * - BTF_SHOW_ZERO: show zero-valued struct/union members; they
180 * are not displayed by default
181 * - BTF_SHOW_UNSAFE: skip use of bpf_probe_read() to safely read
182 * data before displaying it.
184 #define BTF_SHOW_COMPACT BTF_F_COMPACT
185 #define BTF_SHOW_NONAME BTF_F_NONAME
186 #define BTF_SHOW_PTR_RAW BTF_F_PTR_RAW
187 #define BTF_SHOW_ZERO BTF_F_ZERO
188 #define BTF_SHOW_UNSAFE (1ULL << 4)
190 void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj,
192 int btf_type_seq_show_flags(const struct btf *btf, u32 type_id, void *obj,
193 struct seq_file *m, u64 flags);
196 * Copy len bytes of string representation of obj of BTF type_id into buf.
198 * @btf: struct btf object
199 * @type_id: type id of type obj points to
200 * @obj: pointer to typed data
201 * @buf: buffer to write to
202 * @len: maximum length to write to buf
203 * @flags: show options (see above)
205 * Return: length that would have been/was copied as per snprintf, or
208 int btf_type_snprintf_show(const struct btf *btf, u32 type_id, void *obj,
209 char *buf, int len, u64 flags);
211 int btf_get_fd_by_id(u32 id);
212 u32 btf_obj_id(const struct btf *btf);
213 bool btf_is_kernel(const struct btf *btf);
214 bool btf_is_module(const struct btf *btf);
215 struct module *btf_try_get_module(const struct btf *btf);
216 u32 btf_nr_types(const struct btf *btf);
217 bool btf_member_is_reg_int(const struct btf *btf, const struct btf_type *s,
218 const struct btf_member *m,
219 u32 expected_offset, u32 expected_size);
220 struct btf_record *btf_parse_fields(const struct btf *btf, const struct btf_type *t,
221 u32 field_mask, u32 value_size);
222 int btf_check_and_fixup_fields(const struct btf *btf, struct btf_record *rec);
223 bool btf_type_is_void(const struct btf_type *t);
224 s32 btf_find_by_name_kind(const struct btf *btf, const char *name, u8 kind);
225 s32 bpf_find_btf_id(const char *name, u32 kind, struct btf **btf_p);
226 const struct btf_type *btf_type_skip_modifiers(const struct btf *btf,
227 u32 id, u32 *res_id);
228 const struct btf_type *btf_type_resolve_ptr(const struct btf *btf,
229 u32 id, u32 *res_id);
230 const struct btf_type *btf_type_resolve_func_ptr(const struct btf *btf,
231 u32 id, u32 *res_id);
232 const struct btf_type *
233 btf_resolve_size(const struct btf *btf, const struct btf_type *type,
235 const char *btf_type_str(const struct btf_type *t);
237 #define for_each_member(i, struct_type, member) \
238 for (i = 0, member = btf_type_member(struct_type); \
239 i < btf_type_vlen(struct_type); \
242 #define for_each_vsi(i, datasec_type, member) \
243 for (i = 0, member = btf_type_var_secinfo(datasec_type); \
244 i < btf_type_vlen(datasec_type); \
247 static inline bool btf_type_is_ptr(const struct btf_type *t)
249 return BTF_INFO_KIND(t->info) == BTF_KIND_PTR;
252 static inline bool btf_type_is_int(const struct btf_type *t)
254 return BTF_INFO_KIND(t->info) == BTF_KIND_INT;
257 static inline bool btf_type_is_small_int(const struct btf_type *t)
259 return btf_type_is_int(t) && t->size <= sizeof(u64);
262 static inline u8 btf_int_encoding(const struct btf_type *t)
264 return BTF_INT_ENCODING(*(u32 *)(t + 1));
267 static inline bool btf_type_is_signed_int(const struct btf_type *t)
269 return btf_type_is_int(t) && (btf_int_encoding(t) & BTF_INT_SIGNED);
272 static inline bool btf_type_is_enum(const struct btf_type *t)
274 return BTF_INFO_KIND(t->info) == BTF_KIND_ENUM;
277 static inline bool btf_is_any_enum(const struct btf_type *t)
279 return BTF_INFO_KIND(t->info) == BTF_KIND_ENUM ||
280 BTF_INFO_KIND(t->info) == BTF_KIND_ENUM64;
283 static inline bool btf_kind_core_compat(const struct btf_type *t1,
284 const struct btf_type *t2)
286 return BTF_INFO_KIND(t1->info) == BTF_INFO_KIND(t2->info) ||
287 (btf_is_any_enum(t1) && btf_is_any_enum(t2));
290 static inline bool str_is_empty(const char *s)
295 static inline u16 btf_kind(const struct btf_type *t)
297 return BTF_INFO_KIND(t->info);
300 static inline bool btf_is_enum(const struct btf_type *t)
302 return btf_kind(t) == BTF_KIND_ENUM;
305 static inline bool btf_is_enum64(const struct btf_type *t)
307 return btf_kind(t) == BTF_KIND_ENUM64;
310 static inline u64 btf_enum64_value(const struct btf_enum64 *e)
312 return ((u64)e->val_hi32 << 32) | e->val_lo32;
315 static inline bool btf_is_composite(const struct btf_type *t)
317 u16 kind = btf_kind(t);
319 return kind == BTF_KIND_STRUCT || kind == BTF_KIND_UNION;
322 static inline bool btf_is_array(const struct btf_type *t)
324 return btf_kind(t) == BTF_KIND_ARRAY;
327 static inline bool btf_is_int(const struct btf_type *t)
329 return btf_kind(t) == BTF_KIND_INT;
332 static inline bool btf_is_ptr(const struct btf_type *t)
334 return btf_kind(t) == BTF_KIND_PTR;
337 static inline u8 btf_int_offset(const struct btf_type *t)
339 return BTF_INT_OFFSET(*(u32 *)(t + 1));
342 static inline bool btf_type_is_scalar(const struct btf_type *t)
344 return btf_type_is_int(t) || btf_type_is_enum(t);
347 static inline bool btf_type_is_typedef(const struct btf_type *t)
349 return BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF;
352 static inline bool btf_type_is_volatile(const struct btf_type *t)
354 return BTF_INFO_KIND(t->info) == BTF_KIND_VOLATILE;
357 static inline bool btf_type_is_func(const struct btf_type *t)
359 return BTF_INFO_KIND(t->info) == BTF_KIND_FUNC;
362 static inline bool btf_type_is_func_proto(const struct btf_type *t)
364 return BTF_INFO_KIND(t->info) == BTF_KIND_FUNC_PROTO;
367 static inline bool btf_type_is_var(const struct btf_type *t)
369 return BTF_INFO_KIND(t->info) == BTF_KIND_VAR;
372 static inline bool btf_type_is_type_tag(const struct btf_type *t)
374 return BTF_INFO_KIND(t->info) == BTF_KIND_TYPE_TAG;
377 /* union is only a special case of struct:
378 * all its offsetof(member) == 0
380 static inline bool btf_type_is_struct(const struct btf_type *t)
382 u8 kind = BTF_INFO_KIND(t->info);
384 return kind == BTF_KIND_STRUCT || kind == BTF_KIND_UNION;
387 static inline bool __btf_type_is_struct(const struct btf_type *t)
389 return BTF_INFO_KIND(t->info) == BTF_KIND_STRUCT;
392 static inline bool btf_type_is_array(const struct btf_type *t)
394 return BTF_INFO_KIND(t->info) == BTF_KIND_ARRAY;
397 static inline u16 btf_type_vlen(const struct btf_type *t)
399 return BTF_INFO_VLEN(t->info);
402 static inline u16 btf_vlen(const struct btf_type *t)
404 return btf_type_vlen(t);
407 static inline u16 btf_func_linkage(const struct btf_type *t)
409 return BTF_INFO_VLEN(t->info);
412 static inline bool btf_type_kflag(const struct btf_type *t)
414 return BTF_INFO_KFLAG(t->info);
417 static inline u32 __btf_member_bit_offset(const struct btf_type *struct_type,
418 const struct btf_member *member)
420 return btf_type_kflag(struct_type) ? BTF_MEMBER_BIT_OFFSET(member->offset)
424 static inline u32 __btf_member_bitfield_size(const struct btf_type *struct_type,
425 const struct btf_member *member)
427 return btf_type_kflag(struct_type) ? BTF_MEMBER_BITFIELD_SIZE(member->offset)
431 static inline struct btf_member *btf_members(const struct btf_type *t)
433 return (struct btf_member *)(t + 1);
436 static inline u32 btf_member_bit_offset(const struct btf_type *t, u32 member_idx)
438 const struct btf_member *m = btf_members(t) + member_idx;
440 return __btf_member_bit_offset(t, m);
443 static inline u32 btf_member_bitfield_size(const struct btf_type *t, u32 member_idx)
445 const struct btf_member *m = btf_members(t) + member_idx;
447 return __btf_member_bitfield_size(t, m);
450 static inline const struct btf_member *btf_type_member(const struct btf_type *t)
452 return (const struct btf_member *)(t + 1);
455 static inline struct btf_array *btf_array(const struct btf_type *t)
457 return (struct btf_array *)(t + 1);
460 static inline struct btf_enum *btf_enum(const struct btf_type *t)
462 return (struct btf_enum *)(t + 1);
465 static inline struct btf_enum64 *btf_enum64(const struct btf_type *t)
467 return (struct btf_enum64 *)(t + 1);
470 static inline const struct btf_var_secinfo *btf_type_var_secinfo(
471 const struct btf_type *t)
473 return (const struct btf_var_secinfo *)(t + 1);
476 static inline struct btf_param *btf_params(const struct btf_type *t)
478 return (struct btf_param *)(t + 1);
481 static inline int btf_id_cmp_func(const void *a, const void *b)
483 const int *pa = a, *pb = b;
488 static inline bool btf_id_set_contains(const struct btf_id_set *set, u32 id)
490 return bsearch(&id, set->ids, set->cnt, sizeof(u32), btf_id_cmp_func) != NULL;
493 static inline void *btf_id_set8_contains(const struct btf_id_set8 *set, u32 id)
495 return bsearch(&id, set->pairs, set->cnt, sizeof(set->pairs[0]), btf_id_cmp_func);
498 bool btf_param_match_suffix(const struct btf *btf,
499 const struct btf_param *arg,
501 int btf_ctx_arg_offset(const struct btf *btf, const struct btf_type *func_proto,
504 struct bpf_verifier_log;
506 #if defined(CONFIG_BPF_JIT) && defined(CONFIG_BPF_SYSCALL)
507 struct bpf_struct_ops;
508 int __register_bpf_struct_ops(struct bpf_struct_ops *st_ops);
509 const struct bpf_struct_ops_desc *bpf_struct_ops_find_value(struct btf *btf, u32 value_id);
510 const struct bpf_struct_ops_desc *bpf_struct_ops_find(struct btf *btf, u32 type_id);
512 static inline const struct bpf_struct_ops_desc *bpf_struct_ops_find(struct btf *btf, u32 type_id)
518 #ifdef CONFIG_BPF_SYSCALL
519 const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id);
520 const char *btf_name_by_offset(const struct btf *btf, u32 offset);
521 struct btf *btf_parse_vmlinux(void);
522 struct btf *bpf_prog_get_target_btf(const struct bpf_prog *prog);
523 u32 *btf_kfunc_id_set_contains(const struct btf *btf, u32 kfunc_btf_id,
524 const struct bpf_prog *prog);
525 u32 *btf_kfunc_is_modify_return(const struct btf *btf, u32 kfunc_btf_id,
526 const struct bpf_prog *prog);
527 int register_btf_kfunc_id_set(enum bpf_prog_type prog_type,
528 const struct btf_kfunc_id_set *s);
529 int register_btf_fmodret_id_set(const struct btf_kfunc_id_set *kset);
530 s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id);
531 int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_cnt,
532 struct module *owner);
533 struct btf_struct_meta *btf_find_struct_meta(const struct btf *btf, u32 btf_id);
534 bool btf_is_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf,
535 const struct btf_type *t, enum bpf_prog_type prog_type,
537 int get_kern_ctx_btf_id(struct bpf_verifier_log *log, enum bpf_prog_type prog_type);
538 bool btf_types_are_same(const struct btf *btf1, u32 id1,
539 const struct btf *btf2, u32 id2);
541 static inline const struct btf_type *btf_type_by_id(const struct btf *btf,
546 static inline const char *btf_name_by_offset(const struct btf *btf,
551 static inline u32 *btf_kfunc_id_set_contains(const struct btf *btf,
553 struct bpf_prog *prog)
558 static inline int register_btf_kfunc_id_set(enum bpf_prog_type prog_type,
559 const struct btf_kfunc_id_set *s)
563 static inline s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id)
567 static inline int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors,
568 u32 add_cnt, struct module *owner)
572 static inline struct btf_struct_meta *btf_find_struct_meta(const struct btf *btf, u32 btf_id)
577 btf_is_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf,
578 const struct btf_type *t, enum bpf_prog_type prog_type,
583 static inline int get_kern_ctx_btf_id(struct bpf_verifier_log *log,
584 enum bpf_prog_type prog_type) {
587 static inline bool btf_types_are_same(const struct btf *btf1, u32 id1,
588 const struct btf *btf2, u32 id2)
594 static inline bool btf_type_is_struct_ptr(struct btf *btf, const struct btf_type *t)
596 if (!btf_type_is_ptr(t))
599 t = btf_type_skip_modifiers(btf, t->type, NULL);
601 return btf_type_is_struct(t);