1/* SPDX-License-Identifier: GPL-2.0 */
2/* Copyright (c) 2018 Facebook */
3
4#ifndef _LINUX_BTF_H
5#define _LINUX_BTF_H 1
6
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>
13
14#define BTF_TYPE_EMIT(type) ((void)(type *)0)
15#define BTF_TYPE_EMIT_ENUM(enum_val) ((void)enum_val)
16
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
25 * args.
26 *
27 * Consider, for example, the following new task tracepoint:
28 *
29 * SEC("tp_btf/task_newtask")
30 * int BPF_PROG(new_task_tp, struct task_struct *task, u64 clone_flags)
31 * {
32 * ...
33 * }
34 *
35 * And the following kfunc:
36 *
37 * BTF_ID_FLAGS(func, bpf_task_acquire, KF_ACQUIRE | KF_TRUSTED_ARGS)
38 *
39 * All invocations to the kfunc must pass the unmodified, unwalked task:
40 *
41 * bpf_task_acquire(task); // Allowed
42 * bpf_task_acquire(task->last_wakee); // Rejected, walked task
43 *
44 * Programs may also pass referenced tasks directly to the kfunc:
45 *
46 * struct task_struct *acquired;
47 *
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
52 *
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
56 * would be rejected:
57 *
58 * SEC("kretprobe/free_task")
59 * int BPF_PROG(free_task_probe, struct task_struct *tsk)
60 * {
61 * struct task_struct *acquired;
62 *
63 * acquired = bpf_task_acquire(acquired); // Rejected, not a trusted pointer
64 * bpf_task_release(acquired);
65 *
66 * return 0;
67 * }
68 */
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 */
78
79/*
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.
84 */
85#define __bpf_kfunc __used noinline
86
87#define __bpf_kfunc_start_defs() \
88 __diag_push(); \
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")
93
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()
97
98/*
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.
102 */
103#define stringify_struct(x) \
104 ({ BUILD_BUG_ON(sizeof(struct x) < 0); \
105 __stringify(x); })
106
107struct btf;
108struct btf_member;
109struct btf_type;
110union bpf_attr;
111struct btf_show;
112struct btf_id_set;
113struct bpf_prog;
114
115typedef int (*btf_kfunc_filter_t)(const struct bpf_prog *prog, u32 kfunc_id);
116
117struct btf_kfunc_id_set {
118 struct module *owner;
119 struct btf_id_set8 *set;
120 btf_kfunc_filter_t filter;
121};
122
123struct btf_id_dtor_kfunc {
124 u32 btf_id;
125 u32 kfunc_btf_id;
126};
127
128struct btf_struct_meta {
129 u32 btf_id;
130 struct btf_record *record;
131};
132
133struct btf_struct_metas {
134 u32 cnt;
135 struct btf_struct_meta types[];
136};
137
138extern const struct file_operations btf_fops;
139
140const char *btf_get_name(const struct btf *btf);
141void btf_get(struct btf *btf);
142void btf_put(struct btf *btf);
143int btf_new_fd(const union bpf_attr *attr, bpfptr_t uattr, u32 uattr_sz);
144struct btf *btf_get_by_fd(int fd);
145int 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.
150 *
151 * For example:
152 * In describing "const void *", type_id is "const" and "const"
153 * refers to "void *". The return type will be "void *".
154 *
155 * If type_id is a simple "int", then return type will be "int".
156 *
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
165 * has size info.
166 * *type_id and *ret_size will not be changed in the
167 * NULL return case.
168 */
169const struct btf_type *btf_type_id_size(const struct btf *btf,
170 u32 *type_id,
171 u32 *ret_size);
172
173/*
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;
178 * equivalent to %px.
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.
183 */
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)
189
190void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj,
191 struct seq_file *m);
192int btf_type_seq_show_flags(const struct btf *btf, u32 type_id, void *obj,
193 struct seq_file *m, u64 flags);
194
195/*
196 * Copy len bytes of string representation of obj of BTF type_id into buf.
197 *
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)
204 *
205 * Return: length that would have been/was copied as per snprintf, or
206 * negative error.
207 */
208int btf_type_snprintf_show(const struct btf *btf, u32 type_id, void *obj,
209 char *buf, int len, u64 flags);
210
211int btf_get_fd_by_id(u32 id);
212u32 btf_obj_id(const struct btf *btf);
213bool btf_is_kernel(const struct btf *btf);
214bool btf_is_module(const struct btf *btf);
215struct module *btf_try_get_module(const struct btf *btf);
216u32 btf_nr_types(const struct btf *btf);
217bool 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);
220struct btf_record *btf_parse_fields(const struct btf *btf, const struct btf_type *t,
221 u32 field_mask, u32 value_size);
222int btf_check_and_fixup_fields(const struct btf *btf, struct btf_record *rec);
223bool btf_type_is_void(const struct btf_type *t);
224s32 btf_find_by_name_kind(const struct btf *btf, const char *name, u8 kind);
225s32 bpf_find_btf_id(const char *name, u32 kind, struct btf **btf_p);
226const struct btf_type *btf_type_skip_modifiers(const struct btf *btf,
227 u32 id, u32 *res_id);
228const struct btf_type *btf_type_resolve_ptr(const struct btf *btf,
229 u32 id, u32 *res_id);
230const struct btf_type *btf_type_resolve_func_ptr(const struct btf *btf,
231 u32 id, u32 *res_id);
232const struct btf_type *
233btf_resolve_size(const struct btf *btf, const struct btf_type *type,
234 u32 *type_size);
235const char *btf_type_str(const struct btf_type *t);
236
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); \
240 i++, member++)
241
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); \
245 i++, member++)
246
247static inline bool btf_type_is_ptr(const struct btf_type *t)
248{
249 return BTF_INFO_KIND(t->info) == BTF_KIND_PTR;
250}
251
252static inline bool btf_type_is_int(const struct btf_type *t)
253{
254 return BTF_INFO_KIND(t->info) == BTF_KIND_INT;
255}
256
257static inline bool btf_type_is_small_int(const struct btf_type *t)
258{
259 return btf_type_is_int(t) && t->size <= sizeof(u64);
260}
261
262static inline u8 btf_int_encoding(const struct btf_type *t)
263{
264 return BTF_INT_ENCODING(*(u32 *)(t + 1));
265}
266
267static inline bool btf_type_is_signed_int(const struct btf_type *t)
268{
269 return btf_type_is_int(t) && (btf_int_encoding(t) & BTF_INT_SIGNED);
270}
271
272static inline bool btf_type_is_enum(const struct btf_type *t)
273{
274 return BTF_INFO_KIND(t->info) == BTF_KIND_ENUM;
275}
276
277static inline bool btf_is_any_enum(const struct btf_type *t)
278{
279 return BTF_INFO_KIND(t->info) == BTF_KIND_ENUM ||
280 BTF_INFO_KIND(t->info) == BTF_KIND_ENUM64;
281}
282
283static inline bool btf_kind_core_compat(const struct btf_type *t1,
284 const struct btf_type *t2)
285{
286 return BTF_INFO_KIND(t1->info) == BTF_INFO_KIND(t2->info) ||
287 (btf_is_any_enum(t: t1) && btf_is_any_enum(t: t2));
288}
289
290static inline bool str_is_empty(const char *s)
291{
292 return !s || !s[0];
293}
294
295static inline u16 btf_kind(const struct btf_type *t)
296{
297 return BTF_INFO_KIND(t->info);
298}
299
300static inline bool btf_is_enum(const struct btf_type *t)
301{
302 return btf_kind(t) == BTF_KIND_ENUM;
303}
304
305static inline bool btf_is_enum64(const struct btf_type *t)
306{
307 return btf_kind(t) == BTF_KIND_ENUM64;
308}
309
310static inline u64 btf_enum64_value(const struct btf_enum64 *e)
311{
312 return ((u64)e->val_hi32 << 32) | e->val_lo32;
313}
314
315static inline bool btf_is_composite(const struct btf_type *t)
316{
317 u16 kind = btf_kind(t);
318
319 return kind == BTF_KIND_STRUCT || kind == BTF_KIND_UNION;
320}
321
322static inline bool btf_is_array(const struct btf_type *t)
323{
324 return btf_kind(t) == BTF_KIND_ARRAY;
325}
326
327static inline bool btf_is_int(const struct btf_type *t)
328{
329 return btf_kind(t) == BTF_KIND_INT;
330}
331
332static inline bool btf_is_ptr(const struct btf_type *t)
333{
334 return btf_kind(t) == BTF_KIND_PTR;
335}
336
337static inline u8 btf_int_offset(const struct btf_type *t)
338{
339 return BTF_INT_OFFSET(*(u32 *)(t + 1));
340}
341
342static inline bool btf_type_is_scalar(const struct btf_type *t)
343{
344 return btf_type_is_int(t) || btf_type_is_enum(t);
345}
346
347static inline bool btf_type_is_typedef(const struct btf_type *t)
348{
349 return BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF;
350}
351
352static inline bool btf_type_is_volatile(const struct btf_type *t)
353{
354 return BTF_INFO_KIND(t->info) == BTF_KIND_VOLATILE;
355}
356
357static inline bool btf_type_is_func(const struct btf_type *t)
358{
359 return BTF_INFO_KIND(t->info) == BTF_KIND_FUNC;
360}
361
362static inline bool btf_type_is_func_proto(const struct btf_type *t)
363{
364 return BTF_INFO_KIND(t->info) == BTF_KIND_FUNC_PROTO;
365}
366
367static inline bool btf_type_is_var(const struct btf_type *t)
368{
369 return BTF_INFO_KIND(t->info) == BTF_KIND_VAR;
370}
371
372static inline bool btf_type_is_type_tag(const struct btf_type *t)
373{
374 return BTF_INFO_KIND(t->info) == BTF_KIND_TYPE_TAG;
375}
376
377/* union is only a special case of struct:
378 * all its offsetof(member) == 0
379 */
380static inline bool btf_type_is_struct(const struct btf_type *t)
381{
382 u8 kind = BTF_INFO_KIND(t->info);
383
384 return kind == BTF_KIND_STRUCT || kind == BTF_KIND_UNION;
385}
386
387static inline bool __btf_type_is_struct(const struct btf_type *t)
388{
389 return BTF_INFO_KIND(t->info) == BTF_KIND_STRUCT;
390}
391
392static inline bool btf_type_is_array(const struct btf_type *t)
393{
394 return BTF_INFO_KIND(t->info) == BTF_KIND_ARRAY;
395}
396
397static inline u16 btf_type_vlen(const struct btf_type *t)
398{
399 return BTF_INFO_VLEN(t->info);
400}
401
402static inline u16 btf_vlen(const struct btf_type *t)
403{
404 return btf_type_vlen(t);
405}
406
407static inline u16 btf_func_linkage(const struct btf_type *t)
408{
409 return BTF_INFO_VLEN(t->info);
410}
411
412static inline bool btf_type_kflag(const struct btf_type *t)
413{
414 return BTF_INFO_KFLAG(t->info);
415}
416
417static inline u32 __btf_member_bit_offset(const struct btf_type *struct_type,
418 const struct btf_member *member)
419{
420 return btf_type_kflag(t: struct_type) ? BTF_MEMBER_BIT_OFFSET(member->offset)
421 : member->offset;
422}
423
424static inline u32 __btf_member_bitfield_size(const struct btf_type *struct_type,
425 const struct btf_member *member)
426{
427 return btf_type_kflag(t: struct_type) ? BTF_MEMBER_BITFIELD_SIZE(member->offset)
428 : 0;
429}
430
431static inline struct btf_member *btf_members(const struct btf_type *t)
432{
433 return (struct btf_member *)(t + 1);
434}
435
436static inline u32 btf_member_bit_offset(const struct btf_type *t, u32 member_idx)
437{
438 const struct btf_member *m = btf_members(t) + member_idx;
439
440 return __btf_member_bit_offset(struct_type: t, member: m);
441}
442
443static inline u32 btf_member_bitfield_size(const struct btf_type *t, u32 member_idx)
444{
445 const struct btf_member *m = btf_members(t) + member_idx;
446
447 return __btf_member_bitfield_size(struct_type: t, member: m);
448}
449
450static inline const struct btf_member *btf_type_member(const struct btf_type *t)
451{
452 return (const struct btf_member *)(t + 1);
453}
454
455static inline struct btf_array *btf_array(const struct btf_type *t)
456{
457 return (struct btf_array *)(t + 1);
458}
459
460static inline struct btf_enum *btf_enum(const struct btf_type *t)
461{
462 return (struct btf_enum *)(t + 1);
463}
464
465static inline struct btf_enum64 *btf_enum64(const struct btf_type *t)
466{
467 return (struct btf_enum64 *)(t + 1);
468}
469
470static inline const struct btf_var_secinfo *btf_type_var_secinfo(
471 const struct btf_type *t)
472{
473 return (const struct btf_var_secinfo *)(t + 1);
474}
475
476static inline struct btf_param *btf_params(const struct btf_type *t)
477{
478 return (struct btf_param *)(t + 1);
479}
480
481static inline int btf_id_cmp_func(const void *a, const void *b)
482{
483 const int *pa = a, *pb = b;
484
485 return *pa - *pb;
486}
487
488static inline bool btf_id_set_contains(const struct btf_id_set *set, u32 id)
489{
490 return bsearch(key: &id, base: set->ids, num: set->cnt, size: sizeof(u32), cmp: btf_id_cmp_func) != NULL;
491}
492
493static inline void *btf_id_set8_contains(const struct btf_id_set8 *set, u32 id)
494{
495 return bsearch(key: &id, base: set->pairs, num: set->cnt, size: sizeof(set->pairs[0]), cmp: btf_id_cmp_func);
496}
497
498bool btf_param_match_suffix(const struct btf *btf,
499 const struct btf_param *arg,
500 const char *suffix);
501int btf_ctx_arg_offset(const struct btf *btf, const struct btf_type *func_proto,
502 u32 arg_no);
503
504struct bpf_verifier_log;
505
506#if defined(CONFIG_BPF_JIT) && defined(CONFIG_BPF_SYSCALL)
507struct bpf_struct_ops;
508int __register_bpf_struct_ops(struct bpf_struct_ops *st_ops);
509const struct bpf_struct_ops_desc *bpf_struct_ops_find_value(struct btf *btf, u32 value_id);
510const struct bpf_struct_ops_desc *bpf_struct_ops_find(struct btf *btf, u32 type_id);
511#else
512static inline const struct bpf_struct_ops_desc *bpf_struct_ops_find(struct btf *btf, u32 type_id)
513{
514 return NULL;
515}
516#endif
517
518#ifdef CONFIG_BPF_SYSCALL
519const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id);
520const char *btf_name_by_offset(const struct btf *btf, u32 offset);
521struct btf *btf_parse_vmlinux(void);
522struct btf *bpf_prog_get_target_btf(const struct bpf_prog *prog);
523u32 *btf_kfunc_id_set_contains(const struct btf *btf, u32 kfunc_btf_id,
524 const struct bpf_prog *prog);
525u32 *btf_kfunc_is_modify_return(const struct btf *btf, u32 kfunc_btf_id,
526 const struct bpf_prog *prog);
527int register_btf_kfunc_id_set(enum bpf_prog_type prog_type,
528 const struct btf_kfunc_id_set *s);
529int register_btf_fmodret_id_set(const struct btf_kfunc_id_set *kset);
530s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id);
531int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_cnt,
532 struct module *owner);
533struct btf_struct_meta *btf_find_struct_meta(const struct btf *btf, u32 btf_id);
534bool 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,
536 int arg);
537int get_kern_ctx_btf_id(struct bpf_verifier_log *log, enum bpf_prog_type prog_type);
538bool btf_types_are_same(const struct btf *btf1, u32 id1,
539 const struct btf *btf2, u32 id2);
540#else
541static inline const struct btf_type *btf_type_by_id(const struct btf *btf,
542 u32 type_id)
543{
544 return NULL;
545}
546static inline const char *btf_name_by_offset(const struct btf *btf,
547 u32 offset)
548{
549 return NULL;
550}
551static inline u32 *btf_kfunc_id_set_contains(const struct btf *btf,
552 u32 kfunc_btf_id,
553 struct bpf_prog *prog)
554
555{
556 return NULL;
557}
558static inline int register_btf_kfunc_id_set(enum bpf_prog_type prog_type,
559 const struct btf_kfunc_id_set *s)
560{
561 return 0;
562}
563static inline s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id)
564{
565 return -ENOENT;
566}
567static inline int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors,
568 u32 add_cnt, struct module *owner)
569{
570 return 0;
571}
572static inline struct btf_struct_meta *btf_find_struct_meta(const struct btf *btf, u32 btf_id)
573{
574 return NULL;
575}
576static inline bool
577btf_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,
579 int arg)
580{
581 return false;
582}
583static inline int get_kern_ctx_btf_id(struct bpf_verifier_log *log,
584 enum bpf_prog_type prog_type) {
585 return -EINVAL;
586}
587static inline bool btf_types_are_same(const struct btf *btf1, u32 id1,
588 const struct btf *btf2, u32 id2)
589{
590 return false;
591}
592#endif
593
594static inline bool btf_type_is_struct_ptr(struct btf *btf, const struct btf_type *t)
595{
596 if (!btf_type_is_ptr(t))
597 return false;
598
599 t = btf_type_skip_modifiers(btf, id: t->type, NULL);
600
601 return btf_type_is_struct(t);
602}
603
604#endif
605

source code of linux/include/linux/btf.h