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 #define KF_KPTR_GET (1 << 3) /* kfunc returns reference to a kptr */
22 /* Trusted arguments are those which are guaranteed to be valid when passed to
23 * the kfunc. It is used to enforce that pointers obtained from either acquire
24 * kfuncs, or from the main kernel on a tracepoint or struct_ops callback
25 * invocation, remain unmodified when being passed to helpers taking trusted
28 * Consider, for example, the following new task tracepoint:
30 * SEC("tp_btf/task_newtask")
31 * int BPF_PROG(new_task_tp, struct task_struct *task, u64 clone_flags)
36 * And the following kfunc:
38 * BTF_ID_FLAGS(func, bpf_task_acquire, KF_ACQUIRE | KF_TRUSTED_ARGS)
40 * All invocations to the kfunc must pass the unmodified, unwalked task:
42 * bpf_task_acquire(task); // Allowed
43 * bpf_task_acquire(task->last_wakee); // Rejected, walked task
45 * Programs may also pass referenced tasks directly to the kfunc:
47 * struct task_struct *acquired;
49 * acquired = bpf_task_acquire(task); // Allowed, same as above
50 * bpf_task_acquire(acquired); // Allowed
51 * bpf_task_acquire(task); // Allowed
52 * bpf_task_acquire(acquired->last_wakee); // Rejected, walked task
54 * Programs may _not_, however, pass a task from an arbitrary fentry/fexit, or
55 * kprobe/kretprobe to the kfunc, as BPF cannot guarantee that all of these
56 * pointers are guaranteed to be safe. For example, the following BPF program
59 * SEC("kretprobe/free_task")
60 * int BPF_PROG(free_task_probe, struct task_struct *tsk)
62 * struct task_struct *acquired;
64 * acquired = bpf_task_acquire(acquired); // Rejected, not a trusted pointer
65 * bpf_task_release(acquired);
70 #define KF_TRUSTED_ARGS (1 << 4) /* kfunc only takes trusted pointer arguments */
71 #define KF_SLEEPABLE (1 << 5) /* kfunc may sleep */
72 #define KF_DESTRUCTIVE (1 << 6) /* kfunc performs destructive actions */
75 * Return the name of the passed struct, if exists, or halt the build if for
76 * example the structure gets renamed. In this way, developers have to revisit
77 * the code using that structure name, and update it accordingly.
79 #define stringify_struct(x) \
80 ({ BUILD_BUG_ON(sizeof(struct x) < 0); \
90 struct btf_kfunc_id_set {
92 struct btf_id_set8 *set;
95 struct btf_id_dtor_kfunc {
100 struct btf_struct_meta {
102 struct btf_record *record;
103 struct btf_field_offs *field_offs;
106 struct btf_struct_metas {
108 struct btf_struct_meta types[];
111 typedef void (*btf_dtor_kfunc_t)(void *);
113 extern const struct file_operations btf_fops;
115 void btf_get(struct btf *btf);
116 void btf_put(struct btf *btf);
117 int btf_new_fd(const union bpf_attr *attr, bpfptr_t uattr);
118 struct btf *btf_get_by_fd(int fd);
119 int btf_get_info_by_fd(const struct btf *btf,
120 const union bpf_attr *attr,
121 union bpf_attr __user *uattr);
122 /* Figure out the size of a type_id. If type_id is a modifier
123 * (e.g. const), it will be resolved to find out the type with size.
126 * In describing "const void *", type_id is "const" and "const"
127 * refers to "void *". The return type will be "void *".
129 * If type_id is a simple "int", then return type will be "int".
131 * @btf: struct btf object
132 * @type_id: Find out the size of type_id. The type_id of the return
133 * type is set to *type_id.
134 * @ret_size: It can be NULL. If not NULL, the size of the return
135 * type is set to *ret_size.
136 * Return: The btf_type (resolved to another type with size info if needed).
137 * NULL is returned if type_id itself does not have size info
138 * (e.g. void) or it cannot be resolved to another type that
140 * *type_id and *ret_size will not be changed in the
143 const struct btf_type *btf_type_id_size(const struct btf *btf,
148 * Options to control show behaviour.
149 * - BTF_SHOW_COMPACT: no formatting around type information
150 * - BTF_SHOW_NONAME: no struct/union member names/types
151 * - BTF_SHOW_PTR_RAW: show raw (unobfuscated) pointer values;
153 * - BTF_SHOW_ZERO: show zero-valued struct/union members; they
154 * are not displayed by default
155 * - BTF_SHOW_UNSAFE: skip use of bpf_probe_read() to safely read
156 * data before displaying it.
158 #define BTF_SHOW_COMPACT BTF_F_COMPACT
159 #define BTF_SHOW_NONAME BTF_F_NONAME
160 #define BTF_SHOW_PTR_RAW BTF_F_PTR_RAW
161 #define BTF_SHOW_ZERO BTF_F_ZERO
162 #define BTF_SHOW_UNSAFE (1ULL << 4)
164 void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj,
166 int btf_type_seq_show_flags(const struct btf *btf, u32 type_id, void *obj,
167 struct seq_file *m, u64 flags);
170 * Copy len bytes of string representation of obj of BTF type_id into buf.
172 * @btf: struct btf object
173 * @type_id: type id of type obj points to
174 * @obj: pointer to typed data
175 * @buf: buffer to write to
176 * @len: maximum length to write to buf
177 * @flags: show options (see above)
179 * Return: length that would have been/was copied as per snprintf, or
182 int btf_type_snprintf_show(const struct btf *btf, u32 type_id, void *obj,
183 char *buf, int len, u64 flags);
185 int btf_get_fd_by_id(u32 id);
186 u32 btf_obj_id(const struct btf *btf);
187 bool btf_is_kernel(const struct btf *btf);
188 bool btf_is_module(const struct btf *btf);
189 struct module *btf_try_get_module(const struct btf *btf);
190 u32 btf_nr_types(const struct btf *btf);
191 bool btf_member_is_reg_int(const struct btf *btf, const struct btf_type *s,
192 const struct btf_member *m,
193 u32 expected_offset, u32 expected_size);
194 int btf_find_spin_lock(const struct btf *btf, const struct btf_type *t);
195 int btf_find_timer(const struct btf *btf, const struct btf_type *t);
196 struct btf_record *btf_parse_fields(const struct btf *btf, const struct btf_type *t,
197 u32 field_mask, u32 value_size);
198 int btf_check_and_fixup_fields(const struct btf *btf, struct btf_record *rec);
199 struct btf_field_offs *btf_parse_field_offs(struct btf_record *rec);
200 bool btf_type_is_void(const struct btf_type *t);
201 s32 btf_find_by_name_kind(const struct btf *btf, const char *name, u8 kind);
202 const struct btf_type *btf_type_skip_modifiers(const struct btf *btf,
203 u32 id, u32 *res_id);
204 const struct btf_type *btf_type_resolve_ptr(const struct btf *btf,
205 u32 id, u32 *res_id);
206 const struct btf_type *btf_type_resolve_func_ptr(const struct btf *btf,
207 u32 id, u32 *res_id);
208 const struct btf_type *
209 btf_resolve_size(const struct btf *btf, const struct btf_type *type,
211 const char *btf_type_str(const struct btf_type *t);
213 #define for_each_member(i, struct_type, member) \
214 for (i = 0, member = btf_type_member(struct_type); \
215 i < btf_type_vlen(struct_type); \
218 #define for_each_vsi(i, datasec_type, member) \
219 for (i = 0, member = btf_type_var_secinfo(datasec_type); \
220 i < btf_type_vlen(datasec_type); \
223 static inline bool btf_type_is_ptr(const struct btf_type *t)
225 return BTF_INFO_KIND(t->info) == BTF_KIND_PTR;
228 static inline bool btf_type_is_int(const struct btf_type *t)
230 return BTF_INFO_KIND(t->info) == BTF_KIND_INT;
233 static inline bool btf_type_is_small_int(const struct btf_type *t)
235 return btf_type_is_int(t) && t->size <= sizeof(u64);
238 static inline bool btf_type_is_enum(const struct btf_type *t)
240 return BTF_INFO_KIND(t->info) == BTF_KIND_ENUM;
243 static inline bool btf_is_any_enum(const struct btf_type *t)
245 return BTF_INFO_KIND(t->info) == BTF_KIND_ENUM ||
246 BTF_INFO_KIND(t->info) == BTF_KIND_ENUM64;
249 static inline bool btf_kind_core_compat(const struct btf_type *t1,
250 const struct btf_type *t2)
252 return BTF_INFO_KIND(t1->info) == BTF_INFO_KIND(t2->info) ||
253 (btf_is_any_enum(t1) && btf_is_any_enum(t2));
256 static inline bool str_is_empty(const char *s)
261 static inline u16 btf_kind(const struct btf_type *t)
263 return BTF_INFO_KIND(t->info);
266 static inline bool btf_is_enum(const struct btf_type *t)
268 return btf_kind(t) == BTF_KIND_ENUM;
271 static inline bool btf_is_enum64(const struct btf_type *t)
273 return btf_kind(t) == BTF_KIND_ENUM64;
276 static inline u64 btf_enum64_value(const struct btf_enum64 *e)
278 return ((u64)e->val_hi32 << 32) | e->val_lo32;
281 static inline bool btf_is_composite(const struct btf_type *t)
283 u16 kind = btf_kind(t);
285 return kind == BTF_KIND_STRUCT || kind == BTF_KIND_UNION;
288 static inline bool btf_is_array(const struct btf_type *t)
290 return btf_kind(t) == BTF_KIND_ARRAY;
293 static inline bool btf_is_int(const struct btf_type *t)
295 return btf_kind(t) == BTF_KIND_INT;
298 static inline bool btf_is_ptr(const struct btf_type *t)
300 return btf_kind(t) == BTF_KIND_PTR;
303 static inline u8 btf_int_offset(const struct btf_type *t)
305 return BTF_INT_OFFSET(*(u32 *)(t + 1));
308 static inline u8 btf_int_encoding(const struct btf_type *t)
310 return BTF_INT_ENCODING(*(u32 *)(t + 1));
313 static inline bool btf_type_is_scalar(const struct btf_type *t)
315 return btf_type_is_int(t) || btf_type_is_enum(t);
318 static inline bool btf_type_is_typedef(const struct btf_type *t)
320 return BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF;
323 static inline bool btf_type_is_volatile(const struct btf_type *t)
325 return BTF_INFO_KIND(t->info) == BTF_KIND_VOLATILE;
328 static inline bool btf_type_is_func(const struct btf_type *t)
330 return BTF_INFO_KIND(t->info) == BTF_KIND_FUNC;
333 static inline bool btf_type_is_func_proto(const struct btf_type *t)
335 return BTF_INFO_KIND(t->info) == BTF_KIND_FUNC_PROTO;
338 static inline bool btf_type_is_var(const struct btf_type *t)
340 return BTF_INFO_KIND(t->info) == BTF_KIND_VAR;
343 static inline bool btf_type_is_type_tag(const struct btf_type *t)
345 return BTF_INFO_KIND(t->info) == BTF_KIND_TYPE_TAG;
348 /* union is only a special case of struct:
349 * all its offsetof(member) == 0
351 static inline bool btf_type_is_struct(const struct btf_type *t)
353 u8 kind = BTF_INFO_KIND(t->info);
355 return kind == BTF_KIND_STRUCT || kind == BTF_KIND_UNION;
358 static inline bool __btf_type_is_struct(const struct btf_type *t)
360 return BTF_INFO_KIND(t->info) == BTF_KIND_STRUCT;
363 static inline bool btf_type_is_array(const struct btf_type *t)
365 return BTF_INFO_KIND(t->info) == BTF_KIND_ARRAY;
368 static inline u16 btf_type_vlen(const struct btf_type *t)
370 return BTF_INFO_VLEN(t->info);
373 static inline u16 btf_vlen(const struct btf_type *t)
375 return btf_type_vlen(t);
378 static inline u16 btf_func_linkage(const struct btf_type *t)
380 return BTF_INFO_VLEN(t->info);
383 static inline bool btf_type_kflag(const struct btf_type *t)
385 return BTF_INFO_KFLAG(t->info);
388 static inline u32 __btf_member_bit_offset(const struct btf_type *struct_type,
389 const struct btf_member *member)
391 return btf_type_kflag(struct_type) ? BTF_MEMBER_BIT_OFFSET(member->offset)
395 static inline u32 __btf_member_bitfield_size(const struct btf_type *struct_type,
396 const struct btf_member *member)
398 return btf_type_kflag(struct_type) ? BTF_MEMBER_BITFIELD_SIZE(member->offset)
402 static inline struct btf_member *btf_members(const struct btf_type *t)
404 return (struct btf_member *)(t + 1);
407 static inline u32 btf_member_bit_offset(const struct btf_type *t, u32 member_idx)
409 const struct btf_member *m = btf_members(t) + member_idx;
411 return __btf_member_bit_offset(t, m);
414 static inline u32 btf_member_bitfield_size(const struct btf_type *t, u32 member_idx)
416 const struct btf_member *m = btf_members(t) + member_idx;
418 return __btf_member_bitfield_size(t, m);
421 static inline const struct btf_member *btf_type_member(const struct btf_type *t)
423 return (const struct btf_member *)(t + 1);
426 static inline struct btf_array *btf_array(const struct btf_type *t)
428 return (struct btf_array *)(t + 1);
431 static inline struct btf_enum *btf_enum(const struct btf_type *t)
433 return (struct btf_enum *)(t + 1);
436 static inline struct btf_enum64 *btf_enum64(const struct btf_type *t)
438 return (struct btf_enum64 *)(t + 1);
441 static inline const struct btf_var_secinfo *btf_type_var_secinfo(
442 const struct btf_type *t)
444 return (const struct btf_var_secinfo *)(t + 1);
447 static inline struct btf_param *btf_params(const struct btf_type *t)
449 return (struct btf_param *)(t + 1);
452 static inline int btf_id_cmp_func(const void *a, const void *b)
454 const int *pa = a, *pb = b;
459 static inline bool btf_id_set_contains(const struct btf_id_set *set, u32 id)
461 return bsearch(&id, set->ids, set->cnt, sizeof(u32), btf_id_cmp_func) != NULL;
464 static inline void *btf_id_set8_contains(const struct btf_id_set8 *set, u32 id)
466 return bsearch(&id, set->pairs, set->cnt, sizeof(set->pairs[0]), btf_id_cmp_func);
470 struct bpf_verifier_log;
472 #ifdef CONFIG_BPF_SYSCALL
473 const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id);
474 const char *btf_name_by_offset(const struct btf *btf, u32 offset);
475 struct btf *btf_parse_vmlinux(void);
476 struct btf *bpf_prog_get_target_btf(const struct bpf_prog *prog);
477 u32 *btf_kfunc_id_set_contains(const struct btf *btf,
478 enum bpf_prog_type prog_type,
480 int register_btf_kfunc_id_set(enum bpf_prog_type prog_type,
481 const struct btf_kfunc_id_set *s);
482 s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id);
483 int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_cnt,
484 struct module *owner);
485 struct btf_struct_meta *btf_find_struct_meta(const struct btf *btf, u32 btf_id);
486 const struct btf_member *
487 btf_get_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf,
488 const struct btf_type *t, enum bpf_prog_type prog_type,
490 int get_kern_ctx_btf_id(struct bpf_verifier_log *log, enum bpf_prog_type prog_type);
491 bool btf_types_are_same(const struct btf *btf1, u32 id1,
492 const struct btf *btf2, u32 id2);
494 static inline const struct btf_type *btf_type_by_id(const struct btf *btf,
499 static inline const char *btf_name_by_offset(const struct btf *btf,
504 static inline u32 *btf_kfunc_id_set_contains(const struct btf *btf,
505 enum bpf_prog_type prog_type,
510 static inline int register_btf_kfunc_id_set(enum bpf_prog_type prog_type,
511 const struct btf_kfunc_id_set *s)
515 static inline s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id)
519 static inline int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors,
520 u32 add_cnt, struct module *owner)
524 static inline struct btf_struct_meta *btf_find_struct_meta(const struct btf *btf, u32 btf_id)
528 static inline const struct btf_member *
529 btf_get_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf,
530 const struct btf_type *t, enum bpf_prog_type prog_type,
535 static inline int get_kern_ctx_btf_id(struct bpf_verifier_log *log,
536 enum bpf_prog_type prog_type) {
539 static inline bool btf_types_are_same(const struct btf *btf1, u32 id1,
540 const struct btf *btf2, u32 id2)
546 static inline bool btf_type_is_struct_ptr(struct btf *btf, const struct btf_type *t)
548 if (!btf_type_is_ptr(t))
551 t = btf_type_skip_modifiers(btf, t->type, NULL);
553 return btf_type_is_struct(t);