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99c55f7d AS |
1 | /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com |
2 | * | |
3 | * This program is free software; you can redistribute it and/or | |
4 | * modify it under the terms of version 2 of the GNU General Public | |
5 | * License as published by the Free Software Foundation. | |
6 | * | |
7 | * This program is distributed in the hope that it will be useful, but | |
8 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
9 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
10 | * General Public License for more details. | |
11 | */ | |
12 | #include <linux/bpf.h> | |
13 | #include <linux/syscalls.h> | |
14 | #include <linux/slab.h> | |
15 | #include <linux/anon_inodes.h> | |
db20fd2b | 16 | #include <linux/file.h> |
09756af4 AS |
17 | #include <linux/license.h> |
18 | #include <linux/filter.h> | |
99c55f7d AS |
19 | |
20 | static LIST_HEAD(bpf_map_types); | |
21 | ||
22 | static struct bpf_map *find_and_alloc_map(union bpf_attr *attr) | |
23 | { | |
24 | struct bpf_map_type_list *tl; | |
25 | struct bpf_map *map; | |
26 | ||
27 | list_for_each_entry(tl, &bpf_map_types, list_node) { | |
28 | if (tl->type == attr->map_type) { | |
29 | map = tl->ops->map_alloc(attr); | |
30 | if (IS_ERR(map)) | |
31 | return map; | |
32 | map->ops = tl->ops; | |
33 | map->map_type = attr->map_type; | |
34 | return map; | |
35 | } | |
36 | } | |
37 | return ERR_PTR(-EINVAL); | |
38 | } | |
39 | ||
40 | /* boot time registration of different map implementations */ | |
41 | void bpf_register_map_type(struct bpf_map_type_list *tl) | |
42 | { | |
43 | list_add(&tl->list_node, &bpf_map_types); | |
44 | } | |
45 | ||
46 | /* called from workqueue */ | |
47 | static void bpf_map_free_deferred(struct work_struct *work) | |
48 | { | |
49 | struct bpf_map *map = container_of(work, struct bpf_map, work); | |
50 | ||
51 | /* implementation dependent freeing */ | |
52 | map->ops->map_free(map); | |
53 | } | |
54 | ||
55 | /* decrement map refcnt and schedule it for freeing via workqueue | |
56 | * (unrelying map implementation ops->map_free() might sleep) | |
57 | */ | |
58 | void bpf_map_put(struct bpf_map *map) | |
59 | { | |
60 | if (atomic_dec_and_test(&map->refcnt)) { | |
61 | INIT_WORK(&map->work, bpf_map_free_deferred); | |
62 | schedule_work(&map->work); | |
63 | } | |
64 | } | |
65 | ||
66 | static int bpf_map_release(struct inode *inode, struct file *filp) | |
67 | { | |
68 | struct bpf_map *map = filp->private_data; | |
69 | ||
70 | bpf_map_put(map); | |
71 | return 0; | |
72 | } | |
73 | ||
74 | static const struct file_operations bpf_map_fops = { | |
75 | .release = bpf_map_release, | |
76 | }; | |
77 | ||
78 | /* helper macro to check that unused fields 'union bpf_attr' are zero */ | |
79 | #define CHECK_ATTR(CMD) \ | |
80 | memchr_inv((void *) &attr->CMD##_LAST_FIELD + \ | |
81 | sizeof(attr->CMD##_LAST_FIELD), 0, \ | |
82 | sizeof(*attr) - \ | |
83 | offsetof(union bpf_attr, CMD##_LAST_FIELD) - \ | |
84 | sizeof(attr->CMD##_LAST_FIELD)) != NULL | |
85 | ||
86 | #define BPF_MAP_CREATE_LAST_FIELD max_entries | |
87 | /* called via syscall */ | |
88 | static int map_create(union bpf_attr *attr) | |
89 | { | |
90 | struct bpf_map *map; | |
91 | int err; | |
92 | ||
93 | err = CHECK_ATTR(BPF_MAP_CREATE); | |
94 | if (err) | |
95 | return -EINVAL; | |
96 | ||
97 | /* find map type and init map: hashtable vs rbtree vs bloom vs ... */ | |
98 | map = find_and_alloc_map(attr); | |
99 | if (IS_ERR(map)) | |
100 | return PTR_ERR(map); | |
101 | ||
102 | atomic_set(&map->refcnt, 1); | |
103 | ||
104 | err = anon_inode_getfd("bpf-map", &bpf_map_fops, map, O_RDWR | O_CLOEXEC); | |
105 | ||
106 | if (err < 0) | |
107 | /* failed to allocate fd */ | |
108 | goto free_map; | |
109 | ||
110 | return err; | |
111 | ||
112 | free_map: | |
113 | map->ops->map_free(map); | |
114 | return err; | |
115 | } | |
116 | ||
db20fd2b AS |
117 | /* if error is returned, fd is released. |
118 | * On success caller should complete fd access with matching fdput() | |
119 | */ | |
120 | struct bpf_map *bpf_map_get(struct fd f) | |
121 | { | |
122 | struct bpf_map *map; | |
123 | ||
124 | if (!f.file) | |
125 | return ERR_PTR(-EBADF); | |
126 | ||
127 | if (f.file->f_op != &bpf_map_fops) { | |
128 | fdput(f); | |
129 | return ERR_PTR(-EINVAL); | |
130 | } | |
131 | ||
132 | map = f.file->private_data; | |
133 | ||
134 | return map; | |
135 | } | |
136 | ||
137 | /* helper to convert user pointers passed inside __aligned_u64 fields */ | |
138 | static void __user *u64_to_ptr(__u64 val) | |
139 | { | |
140 | return (void __user *) (unsigned long) val; | |
141 | } | |
142 | ||
143 | /* last field in 'union bpf_attr' used by this command */ | |
144 | #define BPF_MAP_LOOKUP_ELEM_LAST_FIELD value | |
145 | ||
146 | static int map_lookup_elem(union bpf_attr *attr) | |
147 | { | |
148 | void __user *ukey = u64_to_ptr(attr->key); | |
149 | void __user *uvalue = u64_to_ptr(attr->value); | |
150 | int ufd = attr->map_fd; | |
151 | struct fd f = fdget(ufd); | |
152 | struct bpf_map *map; | |
8ebe667c | 153 | void *key, *value, *ptr; |
db20fd2b AS |
154 | int err; |
155 | ||
156 | if (CHECK_ATTR(BPF_MAP_LOOKUP_ELEM)) | |
157 | return -EINVAL; | |
158 | ||
159 | map = bpf_map_get(f); | |
160 | if (IS_ERR(map)) | |
161 | return PTR_ERR(map); | |
162 | ||
163 | err = -ENOMEM; | |
164 | key = kmalloc(map->key_size, GFP_USER); | |
165 | if (!key) | |
166 | goto err_put; | |
167 | ||
168 | err = -EFAULT; | |
169 | if (copy_from_user(key, ukey, map->key_size) != 0) | |
170 | goto free_key; | |
171 | ||
8ebe667c AS |
172 | err = -ENOMEM; |
173 | value = kmalloc(map->value_size, GFP_USER); | |
db20fd2b | 174 | if (!value) |
8ebe667c AS |
175 | goto free_key; |
176 | ||
177 | rcu_read_lock(); | |
178 | ptr = map->ops->map_lookup_elem(map, key); | |
179 | if (ptr) | |
180 | memcpy(value, ptr, map->value_size); | |
181 | rcu_read_unlock(); | |
182 | ||
183 | err = -ENOENT; | |
184 | if (!ptr) | |
185 | goto free_value; | |
db20fd2b AS |
186 | |
187 | err = -EFAULT; | |
188 | if (copy_to_user(uvalue, value, map->value_size) != 0) | |
8ebe667c | 189 | goto free_value; |
db20fd2b AS |
190 | |
191 | err = 0; | |
192 | ||
8ebe667c AS |
193 | free_value: |
194 | kfree(value); | |
db20fd2b AS |
195 | free_key: |
196 | kfree(key); | |
197 | err_put: | |
198 | fdput(f); | |
199 | return err; | |
200 | } | |
201 | ||
3274f520 | 202 | #define BPF_MAP_UPDATE_ELEM_LAST_FIELD flags |
db20fd2b AS |
203 | |
204 | static int map_update_elem(union bpf_attr *attr) | |
205 | { | |
206 | void __user *ukey = u64_to_ptr(attr->key); | |
207 | void __user *uvalue = u64_to_ptr(attr->value); | |
208 | int ufd = attr->map_fd; | |
209 | struct fd f = fdget(ufd); | |
210 | struct bpf_map *map; | |
211 | void *key, *value; | |
212 | int err; | |
213 | ||
214 | if (CHECK_ATTR(BPF_MAP_UPDATE_ELEM)) | |
215 | return -EINVAL; | |
216 | ||
217 | map = bpf_map_get(f); | |
218 | if (IS_ERR(map)) | |
219 | return PTR_ERR(map); | |
220 | ||
221 | err = -ENOMEM; | |
222 | key = kmalloc(map->key_size, GFP_USER); | |
223 | if (!key) | |
224 | goto err_put; | |
225 | ||
226 | err = -EFAULT; | |
227 | if (copy_from_user(key, ukey, map->key_size) != 0) | |
228 | goto free_key; | |
229 | ||
230 | err = -ENOMEM; | |
231 | value = kmalloc(map->value_size, GFP_USER); | |
232 | if (!value) | |
233 | goto free_key; | |
234 | ||
235 | err = -EFAULT; | |
236 | if (copy_from_user(value, uvalue, map->value_size) != 0) | |
237 | goto free_value; | |
238 | ||
239 | /* eBPF program that use maps are running under rcu_read_lock(), | |
240 | * therefore all map accessors rely on this fact, so do the same here | |
241 | */ | |
242 | rcu_read_lock(); | |
3274f520 | 243 | err = map->ops->map_update_elem(map, key, value, attr->flags); |
db20fd2b AS |
244 | rcu_read_unlock(); |
245 | ||
246 | free_value: | |
247 | kfree(value); | |
248 | free_key: | |
249 | kfree(key); | |
250 | err_put: | |
251 | fdput(f); | |
252 | return err; | |
253 | } | |
254 | ||
255 | #define BPF_MAP_DELETE_ELEM_LAST_FIELD key | |
256 | ||
257 | static int map_delete_elem(union bpf_attr *attr) | |
258 | { | |
259 | void __user *ukey = u64_to_ptr(attr->key); | |
260 | int ufd = attr->map_fd; | |
261 | struct fd f = fdget(ufd); | |
262 | struct bpf_map *map; | |
263 | void *key; | |
264 | int err; | |
265 | ||
266 | if (CHECK_ATTR(BPF_MAP_DELETE_ELEM)) | |
267 | return -EINVAL; | |
268 | ||
269 | map = bpf_map_get(f); | |
270 | if (IS_ERR(map)) | |
271 | return PTR_ERR(map); | |
272 | ||
273 | err = -ENOMEM; | |
274 | key = kmalloc(map->key_size, GFP_USER); | |
275 | if (!key) | |
276 | goto err_put; | |
277 | ||
278 | err = -EFAULT; | |
279 | if (copy_from_user(key, ukey, map->key_size) != 0) | |
280 | goto free_key; | |
281 | ||
282 | rcu_read_lock(); | |
283 | err = map->ops->map_delete_elem(map, key); | |
284 | rcu_read_unlock(); | |
285 | ||
286 | free_key: | |
287 | kfree(key); | |
288 | err_put: | |
289 | fdput(f); | |
290 | return err; | |
291 | } | |
292 | ||
293 | /* last field in 'union bpf_attr' used by this command */ | |
294 | #define BPF_MAP_GET_NEXT_KEY_LAST_FIELD next_key | |
295 | ||
296 | static int map_get_next_key(union bpf_attr *attr) | |
297 | { | |
298 | void __user *ukey = u64_to_ptr(attr->key); | |
299 | void __user *unext_key = u64_to_ptr(attr->next_key); | |
300 | int ufd = attr->map_fd; | |
301 | struct fd f = fdget(ufd); | |
302 | struct bpf_map *map; | |
303 | void *key, *next_key; | |
304 | int err; | |
305 | ||
306 | if (CHECK_ATTR(BPF_MAP_GET_NEXT_KEY)) | |
307 | return -EINVAL; | |
308 | ||
309 | map = bpf_map_get(f); | |
310 | if (IS_ERR(map)) | |
311 | return PTR_ERR(map); | |
312 | ||
313 | err = -ENOMEM; | |
314 | key = kmalloc(map->key_size, GFP_USER); | |
315 | if (!key) | |
316 | goto err_put; | |
317 | ||
318 | err = -EFAULT; | |
319 | if (copy_from_user(key, ukey, map->key_size) != 0) | |
320 | goto free_key; | |
321 | ||
322 | err = -ENOMEM; | |
323 | next_key = kmalloc(map->key_size, GFP_USER); | |
324 | if (!next_key) | |
325 | goto free_key; | |
326 | ||
327 | rcu_read_lock(); | |
328 | err = map->ops->map_get_next_key(map, key, next_key); | |
329 | rcu_read_unlock(); | |
330 | if (err) | |
331 | goto free_next_key; | |
332 | ||
333 | err = -EFAULT; | |
334 | if (copy_to_user(unext_key, next_key, map->key_size) != 0) | |
335 | goto free_next_key; | |
336 | ||
337 | err = 0; | |
338 | ||
339 | free_next_key: | |
340 | kfree(next_key); | |
341 | free_key: | |
342 | kfree(key); | |
343 | err_put: | |
344 | fdput(f); | |
345 | return err; | |
346 | } | |
347 | ||
09756af4 AS |
348 | static LIST_HEAD(bpf_prog_types); |
349 | ||
350 | static int find_prog_type(enum bpf_prog_type type, struct bpf_prog *prog) | |
351 | { | |
352 | struct bpf_prog_type_list *tl; | |
353 | ||
354 | list_for_each_entry(tl, &bpf_prog_types, list_node) { | |
355 | if (tl->type == type) { | |
356 | prog->aux->ops = tl->ops; | |
357 | prog->aux->prog_type = type; | |
358 | return 0; | |
359 | } | |
360 | } | |
361 | return -EINVAL; | |
362 | } | |
363 | ||
364 | void bpf_register_prog_type(struct bpf_prog_type_list *tl) | |
365 | { | |
366 | list_add(&tl->list_node, &bpf_prog_types); | |
367 | } | |
368 | ||
0a542a86 AS |
369 | /* fixup insn->imm field of bpf_call instructions: |
370 | * if (insn->imm == BPF_FUNC_map_lookup_elem) | |
371 | * insn->imm = bpf_map_lookup_elem - __bpf_call_base; | |
372 | * else if (insn->imm == BPF_FUNC_map_update_elem) | |
373 | * insn->imm = bpf_map_update_elem - __bpf_call_base; | |
374 | * else ... | |
375 | * | |
376 | * this function is called after eBPF program passed verification | |
377 | */ | |
378 | static void fixup_bpf_calls(struct bpf_prog *prog) | |
379 | { | |
380 | const struct bpf_func_proto *fn; | |
381 | int i; | |
382 | ||
383 | for (i = 0; i < prog->len; i++) { | |
384 | struct bpf_insn *insn = &prog->insnsi[i]; | |
385 | ||
386 | if (insn->code == (BPF_JMP | BPF_CALL)) { | |
387 | /* we reach here when program has bpf_call instructions | |
388 | * and it passed bpf_check(), means that | |
389 | * ops->get_func_proto must have been supplied, check it | |
390 | */ | |
391 | BUG_ON(!prog->aux->ops->get_func_proto); | |
392 | ||
393 | fn = prog->aux->ops->get_func_proto(insn->imm); | |
394 | /* all functions that have prototype and verifier allowed | |
395 | * programs to call them, must be real in-kernel functions | |
396 | */ | |
397 | BUG_ON(!fn->func); | |
398 | insn->imm = fn->func - __bpf_call_base; | |
399 | } | |
400 | } | |
401 | } | |
402 | ||
09756af4 AS |
403 | /* drop refcnt on maps used by eBPF program and free auxilary data */ |
404 | static void free_used_maps(struct bpf_prog_aux *aux) | |
405 | { | |
406 | int i; | |
407 | ||
408 | for (i = 0; i < aux->used_map_cnt; i++) | |
409 | bpf_map_put(aux->used_maps[i]); | |
410 | ||
411 | kfree(aux->used_maps); | |
412 | } | |
413 | ||
414 | void bpf_prog_put(struct bpf_prog *prog) | |
415 | { | |
416 | if (atomic_dec_and_test(&prog->aux->refcnt)) { | |
417 | free_used_maps(prog->aux); | |
418 | bpf_prog_free(prog); | |
419 | } | |
420 | } | |
421 | ||
422 | static int bpf_prog_release(struct inode *inode, struct file *filp) | |
423 | { | |
424 | struct bpf_prog *prog = filp->private_data; | |
425 | ||
426 | bpf_prog_put(prog); | |
427 | return 0; | |
428 | } | |
429 | ||
430 | static const struct file_operations bpf_prog_fops = { | |
431 | .release = bpf_prog_release, | |
432 | }; | |
433 | ||
434 | static struct bpf_prog *get_prog(struct fd f) | |
435 | { | |
436 | struct bpf_prog *prog; | |
437 | ||
438 | if (!f.file) | |
439 | return ERR_PTR(-EBADF); | |
440 | ||
441 | if (f.file->f_op != &bpf_prog_fops) { | |
442 | fdput(f); | |
443 | return ERR_PTR(-EINVAL); | |
444 | } | |
445 | ||
446 | prog = f.file->private_data; | |
447 | ||
448 | return prog; | |
449 | } | |
450 | ||
451 | /* called by sockets/tracing/seccomp before attaching program to an event | |
452 | * pairs with bpf_prog_put() | |
453 | */ | |
454 | struct bpf_prog *bpf_prog_get(u32 ufd) | |
455 | { | |
456 | struct fd f = fdget(ufd); | |
457 | struct bpf_prog *prog; | |
458 | ||
459 | prog = get_prog(f); | |
460 | ||
461 | if (IS_ERR(prog)) | |
462 | return prog; | |
463 | ||
464 | atomic_inc(&prog->aux->refcnt); | |
465 | fdput(f); | |
466 | return prog; | |
467 | } | |
468 | ||
469 | /* last field in 'union bpf_attr' used by this command */ | |
cbd35700 | 470 | #define BPF_PROG_LOAD_LAST_FIELD log_buf |
09756af4 AS |
471 | |
472 | static int bpf_prog_load(union bpf_attr *attr) | |
473 | { | |
474 | enum bpf_prog_type type = attr->prog_type; | |
475 | struct bpf_prog *prog; | |
476 | int err; | |
477 | char license[128]; | |
478 | bool is_gpl; | |
479 | ||
480 | if (CHECK_ATTR(BPF_PROG_LOAD)) | |
481 | return -EINVAL; | |
482 | ||
483 | /* copy eBPF program license from user space */ | |
484 | if (strncpy_from_user(license, u64_to_ptr(attr->license), | |
485 | sizeof(license) - 1) < 0) | |
486 | return -EFAULT; | |
487 | license[sizeof(license) - 1] = 0; | |
488 | ||
489 | /* eBPF programs must be GPL compatible to use GPL-ed functions */ | |
490 | is_gpl = license_is_gpl_compatible(license); | |
491 | ||
492 | if (attr->insn_cnt >= BPF_MAXINSNS) | |
493 | return -EINVAL; | |
494 | ||
495 | /* plain bpf_prog allocation */ | |
496 | prog = bpf_prog_alloc(bpf_prog_size(attr->insn_cnt), GFP_USER); | |
497 | if (!prog) | |
498 | return -ENOMEM; | |
499 | ||
500 | prog->len = attr->insn_cnt; | |
501 | ||
502 | err = -EFAULT; | |
503 | if (copy_from_user(prog->insns, u64_to_ptr(attr->insns), | |
504 | prog->len * sizeof(struct bpf_insn)) != 0) | |
505 | goto free_prog; | |
506 | ||
507 | prog->orig_prog = NULL; | |
508 | prog->jited = false; | |
509 | ||
510 | atomic_set(&prog->aux->refcnt, 1); | |
511 | prog->aux->is_gpl_compatible = is_gpl; | |
512 | ||
513 | /* find program type: socket_filter vs tracing_filter */ | |
514 | err = find_prog_type(type, prog); | |
515 | if (err < 0) | |
516 | goto free_prog; | |
517 | ||
518 | /* run eBPF verifier */ | |
51580e79 | 519 | err = bpf_check(prog, attr); |
09756af4 AS |
520 | |
521 | if (err < 0) | |
522 | goto free_used_maps; | |
523 | ||
0a542a86 AS |
524 | /* fixup BPF_CALL->imm field */ |
525 | fixup_bpf_calls(prog); | |
526 | ||
09756af4 AS |
527 | /* eBPF program is ready to be JITed */ |
528 | bpf_prog_select_runtime(prog); | |
529 | ||
530 | err = anon_inode_getfd("bpf-prog", &bpf_prog_fops, prog, O_RDWR | O_CLOEXEC); | |
531 | ||
532 | if (err < 0) | |
533 | /* failed to allocate fd */ | |
534 | goto free_used_maps; | |
535 | ||
536 | return err; | |
537 | ||
538 | free_used_maps: | |
539 | free_used_maps(prog->aux); | |
540 | free_prog: | |
541 | bpf_prog_free(prog); | |
542 | return err; | |
543 | } | |
544 | ||
99c55f7d AS |
545 | SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, size) |
546 | { | |
547 | union bpf_attr attr = {}; | |
548 | int err; | |
549 | ||
550 | /* the syscall is limited to root temporarily. This restriction will be | |
551 | * lifted when security audit is clean. Note that eBPF+tracing must have | |
552 | * this restriction, since it may pass kernel data to user space | |
553 | */ | |
554 | if (!capable(CAP_SYS_ADMIN)) | |
555 | return -EPERM; | |
556 | ||
557 | if (!access_ok(VERIFY_READ, uattr, 1)) | |
558 | return -EFAULT; | |
559 | ||
560 | if (size > PAGE_SIZE) /* silly large */ | |
561 | return -E2BIG; | |
562 | ||
563 | /* If we're handed a bigger struct than we know of, | |
564 | * ensure all the unknown bits are 0 - i.e. new | |
565 | * user-space does not rely on any kernel feature | |
566 | * extensions we dont know about yet. | |
567 | */ | |
568 | if (size > sizeof(attr)) { | |
569 | unsigned char __user *addr; | |
570 | unsigned char __user *end; | |
571 | unsigned char val; | |
572 | ||
573 | addr = (void __user *)uattr + sizeof(attr); | |
574 | end = (void __user *)uattr + size; | |
575 | ||
576 | for (; addr < end; addr++) { | |
577 | err = get_user(val, addr); | |
578 | if (err) | |
579 | return err; | |
580 | if (val) | |
581 | return -E2BIG; | |
582 | } | |
583 | size = sizeof(attr); | |
584 | } | |
585 | ||
586 | /* copy attributes from user space, may be less than sizeof(bpf_attr) */ | |
587 | if (copy_from_user(&attr, uattr, size) != 0) | |
588 | return -EFAULT; | |
589 | ||
590 | switch (cmd) { | |
591 | case BPF_MAP_CREATE: | |
592 | err = map_create(&attr); | |
593 | break; | |
db20fd2b AS |
594 | case BPF_MAP_LOOKUP_ELEM: |
595 | err = map_lookup_elem(&attr); | |
596 | break; | |
597 | case BPF_MAP_UPDATE_ELEM: | |
598 | err = map_update_elem(&attr); | |
599 | break; | |
600 | case BPF_MAP_DELETE_ELEM: | |
601 | err = map_delete_elem(&attr); | |
602 | break; | |
603 | case BPF_MAP_GET_NEXT_KEY: | |
604 | err = map_get_next_key(&attr); | |
605 | break; | |
09756af4 AS |
606 | case BPF_PROG_LOAD: |
607 | err = bpf_prog_load(&attr); | |
608 | break; | |
99c55f7d AS |
609 | default: |
610 | err = -EINVAL; | |
611 | break; | |
612 | } | |
613 | ||
614 | return err; | |
615 | } |