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/*
88 * Return the name of the passed struct, if exists, or halt the build if for
89 * example the structure gets renamed. In this way, developers have to revisit
90 * the code using that structure name, and update it accordingly.
91 */
92#define stringify_struct(x) \
93 ({ BUILD_BUG_ON(sizeof(struct x) < 0); \
94 __stringify(x); })
95
96struct btf;
97struct btf_member;
98struct btf_type;
99union bpf_attr;
100struct btf_show;
101struct btf_id_set;
102struct bpf_prog;
103
104typedef int (*btf_kfunc_filter_t)(const struct bpf_prog *prog, u32 kfunc_id);
105
106struct btf_kfunc_id_set {
107 struct module *owner;
108 struct btf_id_set8 *set;
109 btf_kfunc_filter_t filter;
110};
111
112struct btf_id_dtor_kfunc {
113 u32 btf_id;
114 u32 kfunc_btf_id;
115};
116
117struct btf_struct_meta {
118 u32 btf_id;
119 struct btf_record *record;
120};
121
122struct btf_struct_metas {
123 u32 cnt;
124 struct btf_struct_meta types[];
125};
126
127extern const struct file_operations btf_fops;
128
129void btf_get(struct btf *btf);
130void btf_put(struct btf *btf);
131int btf_new_fd(const union bpf_attr *attr, bpfptr_t uattr, u32 uattr_sz);
132struct btf *btf_get_by_fd(int fd);
133int btf_get_info_by_fd(const struct btf *btf,
134 const union bpf_attr *attr,
135 union bpf_attr __user *uattr);
136/* Figure out the size of a type_id. If type_id is a modifier
137 * (e.g. const), it will be resolved to find out the type with size.
138 *
139 * For example:
140 * In describing "const void *", type_id is "const" and "const"
141 * refers to "void *". The return type will be "void *".
142 *
143 * If type_id is a simple "int", then return type will be "int".
144 *
145 * @btf: struct btf object
146 * @type_id: Find out the size of type_id. The type_id of the return
147 * type is set to *type_id.
148 * @ret_size: It can be NULL. If not NULL, the size of the return
149 * type is set to *ret_size.
150 * Return: The btf_type (resolved to another type with size info if needed).
151 * NULL is returned if type_id itself does not have size info
152 * (e.g. void) or it cannot be resolved to another type that
153 * has size info.
154 * *type_id and *ret_size will not be changed in the
155 * NULL return case.
156 */
157const struct btf_type *btf_type_id_size(const struct btf *btf,
158 u32 *type_id,
159 u32 *ret_size);
160
161/*
162 * Options to control show behaviour.
163 * - BTF_SHOW_COMPACT: no formatting around type information
164 * - BTF_SHOW_NONAME: no struct/union member names/types
165 * - BTF_SHOW_PTR_RAW: show raw (unobfuscated) pointer values;
166 * equivalent to %px.
167 * - BTF_SHOW_ZERO: show zero-valued struct/union members; they
168 * are not displayed by default
169 * - BTF_SHOW_UNSAFE: skip use of bpf_probe_read() to safely read
170 * data before displaying it.
171 */
172#define BTF_SHOW_COMPACT BTF_F_COMPACT
173#define BTF_SHOW_NONAME BTF_F_NONAME
174#define BTF_SHOW_PTR_RAW BTF_F_PTR_RAW
175#define BTF_SHOW_ZERO BTF_F_ZERO
176#define BTF_SHOW_UNSAFE (1ULL << 4)
177
178void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj,
179 struct seq_file *m);
180int btf_type_seq_show_flags(const struct btf *btf, u32 type_id, void *obj,
181 struct seq_file *m, u64 flags);
182
183/*
184 * Copy len bytes of string representation of obj of BTF type_id into buf.
185 *
186 * @btf: struct btf object
187 * @type_id: type id of type obj points to
188 * @obj: pointer to typed data
189 * @buf: buffer to write to
190 * @len: maximum length to write to buf
191 * @flags: show options (see above)
192 *
193 * Return: length that would have been/was copied as per snprintf, or
194 * negative error.
195 */
196int btf_type_snprintf_show(const struct btf *btf, u32 type_id, void *obj,
197 char *buf, int len, u64 flags);
198
199int btf_get_fd_by_id(u32 id);
200u32 btf_obj_id(const struct btf *btf);
201bool btf_is_kernel(const struct btf *btf);
202bool btf_is_module(const struct btf *btf);
203struct module *btf_try_get_module(const struct btf *btf);
204u32 btf_nr_types(const struct btf *btf);
205bool btf_member_is_reg_int(const struct btf *btf, const struct btf_type *s,
206 const struct btf_member *m,
207 u32 expected_offset, u32 expected_size);
208struct btf_record *btf_parse_fields(const struct btf *btf, const struct btf_type *t,
209 u32 field_mask, u32 value_size);
210int btf_check_and_fixup_fields(const struct btf *btf, struct btf_record *rec);
211bool btf_type_is_void(const struct btf_type *t);
212s32 btf_find_by_name_kind(const struct btf *btf, const char *name, u8 kind);
213s32 bpf_find_btf_id(const char *name, u32 kind, struct btf **btf_p);
214const struct btf_type *btf_type_skip_modifiers(const struct btf *btf,
215 u32 id, u32 *res_id);
216const struct btf_type *btf_type_resolve_ptr(const struct btf *btf,
217 u32 id, u32 *res_id);
218const struct btf_type *btf_type_resolve_func_ptr(const struct btf *btf,
219 u32 id, u32 *res_id);
220const struct btf_type *
221btf_resolve_size(const struct btf *btf, const struct btf_type *type,
222 u32 *type_size);
223const char *btf_type_str(const struct btf_type *t);
224
225#define for_each_member(i, struct_type, member) \
226 for (i = 0, member = btf_type_member(struct_type); \
227 i < btf_type_vlen(struct_type); \
228 i++, member++)
229
230#define for_each_vsi(i, datasec_type, member) \
231 for (i = 0, member = btf_type_var_secinfo(datasec_type); \
232 i < btf_type_vlen(datasec_type); \
233 i++, member++)
234
235static inline bool btf_type_is_ptr(const struct btf_type *t)
236{
237 return BTF_INFO_KIND(t->info) == BTF_KIND_PTR;
238}
239
240static inline bool btf_type_is_int(const struct btf_type *t)
241{
242 return BTF_INFO_KIND(t->info) == BTF_KIND_INT;
243}
244
245static inline bool btf_type_is_small_int(const struct btf_type *t)
246{
247 return btf_type_is_int(t) && t->size <= sizeof(u64);
248}
249
250static inline u8 btf_int_encoding(const struct btf_type *t)
251{
252 return BTF_INT_ENCODING(*(u32 *)(t + 1));
253}
254
255static inline bool btf_type_is_signed_int(const struct btf_type *t)
256{
257 return btf_type_is_int(t) && (btf_int_encoding(t) & BTF_INT_SIGNED);
258}
259
260static inline bool btf_type_is_enum(const struct btf_type *t)
261{
262 return BTF_INFO_KIND(t->info) == BTF_KIND_ENUM;
263}
264
265static inline bool btf_is_any_enum(const struct btf_type *t)
266{
267 return BTF_INFO_KIND(t->info) == BTF_KIND_ENUM ||
268 BTF_INFO_KIND(t->info) == BTF_KIND_ENUM64;
269}
270
271static inline bool btf_kind_core_compat(const struct btf_type *t1,
272 const struct btf_type *t2)
273{
274 return BTF_INFO_KIND(t1->info) == BTF_INFO_KIND(t2->info) ||
275 (btf_is_any_enum(t: t1) && btf_is_any_enum(t: t2));
276}
277
278static inline bool str_is_empty(const char *s)
279{
280 return !s || !s[0];
281}
282
283static inline u16 btf_kind(const struct btf_type *t)
284{
285 return BTF_INFO_KIND(t->info);
286}
287
288static inline bool btf_is_enum(const struct btf_type *t)
289{
290 return btf_kind(t) == BTF_KIND_ENUM;
291}
292
293static inline bool btf_is_enum64(const struct btf_type *t)
294{
295 return btf_kind(t) == BTF_KIND_ENUM64;
296}
297
298static inline u64 btf_enum64_value(const struct btf_enum64 *e)
299{
300 return ((u64)e->val_hi32 << 32) | e->val_lo32;
301}
302
303static inline bool btf_is_composite(const struct btf_type *t)
304{
305 u16 kind = btf_kind(t);
306
307 return kind == BTF_KIND_STRUCT || kind == BTF_KIND_UNION;
308}
309
310static inline bool btf_is_array(const struct btf_type *t)
311{
312 return btf_kind(t) == BTF_KIND_ARRAY;
313}
314
315static inline bool btf_is_int(const struct btf_type *t)
316{
317 return btf_kind(t) == BTF_KIND_INT;
318}
319
320static inline bool btf_is_ptr(const struct btf_type *t)
321{
322 return btf_kind(t) == BTF_KIND_PTR;
323}
324
325static inline u8 btf_int_offset(const struct btf_type *t)
326{
327 return BTF_INT_OFFSET(*(u32 *)(t + 1));
328}
329
330static inline bool btf_type_is_scalar(const struct btf_type *t)
331{
332 return btf_type_is_int(t) || btf_type_is_enum(t);
333}
334
335static inline bool btf_type_is_typedef(const struct btf_type *t)
336{
337 return BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF;
338}
339
340static inline bool btf_type_is_volatile(const struct btf_type *t)
341{
342 return BTF_INFO_KIND(t->info) == BTF_KIND_VOLATILE;
343}
344
345static inline bool btf_type_is_func(const struct btf_type *t)
346{
347 return BTF_INFO_KIND(t->info) == BTF_KIND_FUNC;
348}
349
350static inline bool btf_type_is_func_proto(const struct btf_type *t)
351{
352 return BTF_INFO_KIND(t->info) == BTF_KIND_FUNC_PROTO;
353}
354
355static inline bool btf_type_is_var(const struct btf_type *t)
356{
357 return BTF_INFO_KIND(t->info) == BTF_KIND_VAR;
358}
359
360static inline bool btf_type_is_type_tag(const struct btf_type *t)
361{
362 return BTF_INFO_KIND(t->info) == BTF_KIND_TYPE_TAG;
363}
364
365/* union is only a special case of struct:
366 * all its offsetof(member) == 0
367 */
368static inline bool btf_type_is_struct(const struct btf_type *t)
369{
370 u8 kind = BTF_INFO_KIND(t->info);
371
372 return kind == BTF_KIND_STRUCT || kind == BTF_KIND_UNION;
373}
374
375static inline bool __btf_type_is_struct(const struct btf_type *t)
376{
377 return BTF_INFO_KIND(t->info) == BTF_KIND_STRUCT;
378}
379
380static inline bool btf_type_is_array(const struct btf_type *t)
381{
382 return BTF_INFO_KIND(t->info) == BTF_KIND_ARRAY;
383}
384
385static inline u16 btf_type_vlen(const struct btf_type *t)
386{
387 return BTF_INFO_VLEN(t->info);
388}
389
390static inline u16 btf_vlen(const struct btf_type *t)
391{
392 return btf_type_vlen(t);
393}
394
395static inline u16 btf_func_linkage(const struct btf_type *t)
396{
397 return BTF_INFO_VLEN(t->info);
398}
399
400static inline bool btf_type_kflag(const struct btf_type *t)
401{
402 return BTF_INFO_KFLAG(t->info);
403}
404
405static inline u32 __btf_member_bit_offset(const struct btf_type *struct_type,
406 const struct btf_member *member)
407{
408 return btf_type_kflag(t: struct_type) ? BTF_MEMBER_BIT_OFFSET(member->offset)
409 : member->offset;
410}
411
412static inline u32 __btf_member_bitfield_size(const struct btf_type *struct_type,
413 const struct btf_member *member)
414{
415 return btf_type_kflag(t: struct_type) ? BTF_MEMBER_BITFIELD_SIZE(member->offset)
416 : 0;
417}
418
419static inline struct btf_member *btf_members(const struct btf_type *t)
420{
421 return (struct btf_member *)(t + 1);
422}
423
424static inline u32 btf_member_bit_offset(const struct btf_type *t, u32 member_idx)
425{
426 const struct btf_member *m = btf_members(t) + member_idx;
427
428 return __btf_member_bit_offset(struct_type: t, member: m);
429}
430
431static inline u32 btf_member_bitfield_size(const struct btf_type *t, u32 member_idx)
432{
433 const struct btf_member *m = btf_members(t) + member_idx;
434
435 return __btf_member_bitfield_size(struct_type: t, member: m);
436}
437
438static inline const struct btf_member *btf_type_member(const struct btf_type *t)
439{
440 return (const struct btf_member *)(t + 1);
441}
442
443static inline struct btf_array *btf_array(const struct btf_type *t)
444{
445 return (struct btf_array *)(t + 1);
446}
447
448static inline struct btf_enum *btf_enum(const struct btf_type *t)
449{
450 return (struct btf_enum *)(t + 1);
451}
452
453static inline struct btf_enum64 *btf_enum64(const struct btf_type *t)
454{
455 return (struct btf_enum64 *)(t + 1);
456}
457
458static inline const struct btf_var_secinfo *btf_type_var_secinfo(
459 const struct btf_type *t)
460{
461 return (const struct btf_var_secinfo *)(t + 1);
462}
463
464static inline struct btf_param *btf_params(const struct btf_type *t)
465{
466 return (struct btf_param *)(t + 1);
467}
468
469static inline int btf_id_cmp_func(const void *a, const void *b)
470{
471 const int *pa = a, *pb = b;
472
473 return *pa - *pb;
474}
475
476static inline bool btf_id_set_contains(const struct btf_id_set *set, u32 id)
477{
478 return bsearch(key: &id, base: set->ids, num: set->cnt, size: sizeof(u32), cmp: btf_id_cmp_func) != NULL;
479}
480
481static inline void *btf_id_set8_contains(const struct btf_id_set8 *set, u32 id)
482{
483 return bsearch(key: &id, base: set->pairs, num: set->cnt, size: sizeof(set->pairs[0]), cmp: btf_id_cmp_func);
484}
485
486struct bpf_verifier_log;
487
488#ifdef CONFIG_BPF_SYSCALL
489const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id);
490const char *btf_name_by_offset(const struct btf *btf, u32 offset);
491struct btf *btf_parse_vmlinux(void);
492struct btf *bpf_prog_get_target_btf(const struct bpf_prog *prog);
493u32 *btf_kfunc_id_set_contains(const struct btf *btf, u32 kfunc_btf_id,
494 const struct bpf_prog *prog);
495u32 *btf_kfunc_is_modify_return(const struct btf *btf, u32 kfunc_btf_id,
496 const struct bpf_prog *prog);
497int register_btf_kfunc_id_set(enum bpf_prog_type prog_type,
498 const struct btf_kfunc_id_set *s);
499int register_btf_fmodret_id_set(const struct btf_kfunc_id_set *kset);
500s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id);
501int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_cnt,
502 struct module *owner);
503struct btf_struct_meta *btf_find_struct_meta(const struct btf *btf, u32 btf_id);
504const struct btf_member *
505btf_get_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf,
506 const struct btf_type *t, enum bpf_prog_type prog_type,
507 int arg);
508int get_kern_ctx_btf_id(struct bpf_verifier_log *log, enum bpf_prog_type prog_type);
509bool btf_types_are_same(const struct btf *btf1, u32 id1,
510 const struct btf *btf2, u32 id2);
511#else
512static inline const struct btf_type *btf_type_by_id(const struct btf *btf,
513 u32 type_id)
514{
515 return NULL;
516}
517static inline const char *btf_name_by_offset(const struct btf *btf,
518 u32 offset)
519{
520 return NULL;
521}
522static inline u32 *btf_kfunc_id_set_contains(const struct btf *btf,
523 u32 kfunc_btf_id,
524 struct bpf_prog *prog)
525
526{
527 return NULL;
528}
529static inline int register_btf_kfunc_id_set(enum bpf_prog_type prog_type,
530 const struct btf_kfunc_id_set *s)
531{
532 return 0;
533}
534static inline s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id)
535{
536 return -ENOENT;
537}
538static inline int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors,
539 u32 add_cnt, struct module *owner)
540{
541 return 0;
542}
543static inline struct btf_struct_meta *btf_find_struct_meta(const struct btf *btf, u32 btf_id)
544{
545 return NULL;
546}
547static inline const struct btf_member *
548btf_get_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf,
549 const struct btf_type *t, enum bpf_prog_type prog_type,
550 int arg)
551{
552 return NULL;
553}
554static inline int get_kern_ctx_btf_id(struct bpf_verifier_log *log,
555 enum bpf_prog_type prog_type) {
556 return -EINVAL;
557}
558static inline bool btf_types_are_same(const struct btf *btf1, u32 id1,
559 const struct btf *btf2, u32 id2)
560{
561 return false;
562}
563#endif
564
565static inline bool btf_type_is_struct_ptr(struct btf *btf, const struct btf_type *t)
566{
567 if (!btf_type_is_ptr(t))
568 return false;
569
570 t = btf_type_skip_modifiers(btf, id: t->type, NULL);
571
572 return btf_type_is_struct(t);
573}
574
575#endif
576

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