projects/linux·blob v4.12-rc4 · refs

602 lines · 15.2 KiB

1/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
2 * Copyright (c) 2016,2017 Facebook
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of version 2 of the GNU General Public
6 * License as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 */
13#include <linux/bpf.h>
14#include <linux/err.h>
15#include <linux/slab.h>
16#include <linux/mm.h>
17#include <linux/filter.h>
18#include <linux/perf_event.h>
19
20#include "map_in_map.h"
21
22static void bpf_array_free_percpu(struct bpf_array *array)
23{
24 int i;
25
26 for (i = 0; i < array->map.max_entries; i++)
27 free_percpu(array->pptrs[i]);
28}
29
30static int bpf_array_alloc_percpu(struct bpf_array *array)
31{
32 void __percpu *ptr;
33 int i;
34
35 for (i = 0; i < array->map.max_entries; i++) {
36 ptr = __alloc_percpu_gfp(array->elem_size, 8,
37 GFP_USER | __GFP_NOWARN);
38 if (!ptr) {
39 bpf_array_free_percpu(array);
40 return -ENOMEM;
41 }
42 array->pptrs[i] = ptr;
43 }
44
45 return 0;
46}
47
48/* Called from syscall */
49static struct bpf_map *array_map_alloc(union bpf_attr *attr)
50{
51 bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_ARRAY;
52 struct bpf_array *array;
53 u64 array_size;
54 u32 elem_size;
55
56 /* check sanity of attributes */
57 if (attr->max_entries == 0 || attr->key_size != 4 ||
58 attr->value_size == 0 || attr->map_flags)
59 return ERR_PTR(-EINVAL);
60
61 if (attr->value_size > KMALLOC_MAX_SIZE)
62 /* if value_size is bigger, the user space won't be able to
63 * access the elements.
64 */
65 return ERR_PTR(-E2BIG);
66
67 elem_size = round_up(attr->value_size, 8);
68
69 array_size = sizeof(*array);
70 if (percpu)
71 array_size += (u64) attr->max_entries * sizeof(void *);
72 else
73 array_size += (u64) attr->max_entries * elem_size;
74
75 /* make sure there is no u32 overflow later in round_up() */
76 if (array_size >= U32_MAX - PAGE_SIZE)
77 return ERR_PTR(-ENOMEM);
78
79 /* allocate all map elements and zero-initialize them */
80 array = bpf_map_area_alloc(array_size);
81 if (!array)
82 return ERR_PTR(-ENOMEM);
83
84 /* copy mandatory map attributes */
85 array->map.map_type = attr->map_type;
86 array->map.key_size = attr->key_size;
87 array->map.value_size = attr->value_size;
88 array->map.max_entries = attr->max_entries;
89 array->map.map_flags = attr->map_flags;
90 array->elem_size = elem_size;
91
92 if (!percpu)
93 goto out;
94
95 array_size += (u64) attr->max_entries * elem_size * num_possible_cpus();
96
97 if (array_size >= U32_MAX - PAGE_SIZE ||
98 elem_size > PCPU_MIN_UNIT_SIZE || bpf_array_alloc_percpu(array)) {
99 bpf_map_area_free(array);
100 return ERR_PTR(-ENOMEM);
101 }
102out:
103 array->map.pages = round_up(array_size, PAGE_SIZE) >> PAGE_SHIFT;
104
105 return &array->map;
106}
107
108/* Called from syscall or from eBPF program */
109static void *array_map_lookup_elem(struct bpf_map *map, void *key)
110{
111 struct bpf_array *array = container_of(map, struct bpf_array, map);
112 u32 index = *(u32 *)key;
113
114 if (unlikely(index >= array->map.max_entries))
115 return NULL;
116
117 return array->value + array->elem_size * index;
118}
119
120/* emit BPF instructions equivalent to C code of array_map_lookup_elem() */
121static u32 array_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
122{
123 struct bpf_insn *insn = insn_buf;
124 u32 elem_size = round_up(map->value_size, 8);
125 const int ret = BPF_REG_0;
126 const int map_ptr = BPF_REG_1;
127 const int index = BPF_REG_2;
128
129 *insn++ = BPF_ALU64_IMM(BPF_ADD, map_ptr, offsetof(struct bpf_array, value));
130 *insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0);
131 *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 3);
132
133 if (is_power_of_2(elem_size)) {
134 *insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(elem_size));
135 } else {
136 *insn++ = BPF_ALU64_IMM(BPF_MUL, ret, elem_size);
137 }
138 *insn++ = BPF_ALU64_REG(BPF_ADD, ret, map_ptr);
139 *insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
140 *insn++ = BPF_MOV64_IMM(ret, 0);
141 return insn - insn_buf;
142}
143
144/* Called from eBPF program */
145static void *percpu_array_map_lookup_elem(struct bpf_map *map, void *key)
146{
147 struct bpf_array *array = container_of(map, struct bpf_array, map);
148 u32 index = *(u32 *)key;
149
150 if (unlikely(index >= array->map.max_entries))
151 return NULL;
152
153 return this_cpu_ptr(array->pptrs[index]);
154}
155
156int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value)
157{
158 struct bpf_array *array = container_of(map, struct bpf_array, map);
159 u32 index = *(u32 *)key;
160 void __percpu *pptr;
161 int cpu, off = 0;
162 u32 size;
163
164 if (unlikely(index >= array->map.max_entries))
165 return -ENOENT;
166
167 /* per_cpu areas are zero-filled and bpf programs can only
168 * access 'value_size' of them, so copying rounded areas
169 * will not leak any kernel data
170 */
171 size = round_up(map->value_size, 8);
172 rcu_read_lock();
173 pptr = array->pptrs[index];
174 for_each_possible_cpu(cpu) {
175 bpf_long_memcpy(value + off, per_cpu_ptr(pptr, cpu), size);
176 off += size;
177 }
178 rcu_read_unlock();
179 return 0;
180}
181
182/* Called from syscall */
183static int array_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
184{
185 struct bpf_array *array = container_of(map, struct bpf_array, map);
186 u32 index = key ? *(u32 *)key : U32_MAX;
187 u32 *next = (u32 *)next_key;
188
189 if (index >= array->map.max_entries) {
190 *next = 0;
191 return 0;
192 }
193
194 if (index == array->map.max_entries - 1)
195 return -ENOENT;
196
197 *next = index + 1;
198 return 0;
199}
200
201/* Called from syscall or from eBPF program */
202static int array_map_update_elem(struct bpf_map *map, void *key, void *value,
203 u64 map_flags)
204{
205 struct bpf_array *array = container_of(map, struct bpf_array, map);
206 u32 index = *(u32 *)key;
207
208 if (unlikely(map_flags > BPF_EXIST))
209 /* unknown flags */
210 return -EINVAL;
211
212 if (unlikely(index >= array->map.max_entries))
213 /* all elements were pre-allocated, cannot insert a new one */
214 return -E2BIG;
215
216 if (unlikely(map_flags == BPF_NOEXIST))
217 /* all elements already exist */
218 return -EEXIST;
219
220 if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
221 memcpy(this_cpu_ptr(array->pptrs[index]),
222 value, map->value_size);
223 else
224 memcpy(array->value + array->elem_size * index,
225 value, map->value_size);
226 return 0;
227}
228
229int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value,
230 u64 map_flags)
231{
232 struct bpf_array *array = container_of(map, struct bpf_array, map);
233 u32 index = *(u32 *)key;
234 void __percpu *pptr;
235 int cpu, off = 0;
236 u32 size;
237
238 if (unlikely(map_flags > BPF_EXIST))
239 /* unknown flags */
240 return -EINVAL;
241
242 if (unlikely(index >= array->map.max_entries))
243 /* all elements were pre-allocated, cannot insert a new one */
244 return -E2BIG;
245
246 if (unlikely(map_flags == BPF_NOEXIST))
247 /* all elements already exist */
248 return -EEXIST;
249
250 /* the user space will provide round_up(value_size, 8) bytes that
251 * will be copied into per-cpu area. bpf programs can only access
252 * value_size of it. During lookup the same extra bytes will be
253 * returned or zeros which were zero-filled by percpu_alloc,
254 * so no kernel data leaks possible
255 */
256 size = round_up(map->value_size, 8);
257 rcu_read_lock();
258 pptr = array->pptrs[index];
259 for_each_possible_cpu(cpu) {
260 bpf_long_memcpy(per_cpu_ptr(pptr, cpu), value + off, size);
261 off += size;
262 }
263 rcu_read_unlock();
264 return 0;
265}
266
267/* Called from syscall or from eBPF program */
268static int array_map_delete_elem(struct bpf_map *map, void *key)
269{
270 return -EINVAL;
271}
272
273/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
274static void array_map_free(struct bpf_map *map)
275{
276 struct bpf_array *array = container_of(map, struct bpf_array, map);
277
278 /* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
279 * so the programs (can be more than one that used this map) were
280 * disconnected from events. Wait for outstanding programs to complete
281 * and free the array
282 */
283 synchronize_rcu();
284
285 if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
286 bpf_array_free_percpu(array);
287
288 bpf_map_area_free(array);
289}
290
291const struct bpf_map_ops array_map_ops = {
292 .map_alloc = array_map_alloc,
293 .map_free = array_map_free,
294 .map_get_next_key = array_map_get_next_key,
295 .map_lookup_elem = array_map_lookup_elem,
296 .map_update_elem = array_map_update_elem,
297 .map_delete_elem = array_map_delete_elem,
298 .map_gen_lookup = array_map_gen_lookup,
299};
300
301const struct bpf_map_ops percpu_array_map_ops = {
302 .map_alloc = array_map_alloc,
303 .map_free = array_map_free,
304 .map_get_next_key = array_map_get_next_key,
305 .map_lookup_elem = percpu_array_map_lookup_elem,
306 .map_update_elem = array_map_update_elem,
307 .map_delete_elem = array_map_delete_elem,
308};
309
310static struct bpf_map *fd_array_map_alloc(union bpf_attr *attr)
311{
312 /* only file descriptors can be stored in this type of map */
313 if (attr->value_size != sizeof(u32))
314 return ERR_PTR(-EINVAL);
315 return array_map_alloc(attr);
316}
317
318static void fd_array_map_free(struct bpf_map *map)
319{
320 struct bpf_array *array = container_of(map, struct bpf_array, map);
321 int i;
322
323 synchronize_rcu();
324
325 /* make sure it's empty */
326 for (i = 0; i < array->map.max_entries; i++)
327 BUG_ON(array->ptrs[i] != NULL);
328
329 bpf_map_area_free(array);
330}
331
332static void *fd_array_map_lookup_elem(struct bpf_map *map, void *key)
333{
334 return NULL;
335}
336
337/* only called from syscall */
338int bpf_fd_array_map_update_elem(struct bpf_map *map, struct file *map_file,
339 void *key, void *value, u64 map_flags)
340{
341 struct bpf_array *array = container_of(map, struct bpf_array, map);
342 void *new_ptr, *old_ptr;
343 u32 index = *(u32 *)key, ufd;
344
345 if (map_flags != BPF_ANY)
346 return -EINVAL;
347
348 if (index >= array->map.max_entries)
349 return -E2BIG;
350
351 ufd = *(u32 *)value;
352 new_ptr = map->ops->map_fd_get_ptr(map, map_file, ufd);
353 if (IS_ERR(new_ptr))
354 return PTR_ERR(new_ptr);
355
356 old_ptr = xchg(array->ptrs + index, new_ptr);
357 if (old_ptr)
358 map->ops->map_fd_put_ptr(old_ptr);
359
360 return 0;
361}
362
363static int fd_array_map_delete_elem(struct bpf_map *map, void *key)
364{
365 struct bpf_array *array = container_of(map, struct bpf_array, map);
366 void *old_ptr;
367 u32 index = *(u32 *)key;
368
369 if (index >= array->map.max_entries)
370 return -E2BIG;
371
372 old_ptr = xchg(array->ptrs + index, NULL);
373 if (old_ptr) {
374 map->ops->map_fd_put_ptr(old_ptr);
375 return 0;
376 } else {
377 return -ENOENT;
378 }
379}
380
381static void *prog_fd_array_get_ptr(struct bpf_map *map,
382 struct file *map_file, int fd)
383{
384 struct bpf_array *array = container_of(map, struct bpf_array, map);
385 struct bpf_prog *prog = bpf_prog_get(fd);
386
387 if (IS_ERR(prog))
388 return prog;
389
390 if (!bpf_prog_array_compatible(array, prog)) {
391 bpf_prog_put(prog);
392 return ERR_PTR(-EINVAL);
393 }
394
395 return prog;
396}
397
398static void prog_fd_array_put_ptr(void *ptr)
399{
400 bpf_prog_put(ptr);
401}
402
403/* decrement refcnt of all bpf_progs that are stored in this map */
404void bpf_fd_array_map_clear(struct bpf_map *map)
405{
406 struct bpf_array *array = container_of(map, struct bpf_array, map);
407 int i;
408
409 for (i = 0; i < array->map.max_entries; i++)
410 fd_array_map_delete_elem(map, &i);
411}
412
413const struct bpf_map_ops prog_array_map_ops = {
414 .map_alloc = fd_array_map_alloc,
415 .map_free = fd_array_map_free,
416 .map_get_next_key = array_map_get_next_key,
417 .map_lookup_elem = fd_array_map_lookup_elem,
418 .map_delete_elem = fd_array_map_delete_elem,
419 .map_fd_get_ptr = prog_fd_array_get_ptr,
420 .map_fd_put_ptr = prog_fd_array_put_ptr,
421};
422
423static struct bpf_event_entry *bpf_event_entry_gen(struct file *perf_file,
424 struct file *map_file)
425{
426 struct bpf_event_entry *ee;
427
428 ee = kzalloc(sizeof(*ee), GFP_ATOMIC);
429 if (ee) {
430 ee->event = perf_file->private_data;
431 ee->perf_file = perf_file;
432 ee->map_file = map_file;
433 }
434
435 return ee;
436}
437
438static void __bpf_event_entry_free(struct rcu_head *rcu)
439{
440 struct bpf_event_entry *ee;
441
442 ee = container_of(rcu, struct bpf_event_entry, rcu);
443 fput(ee->perf_file);
444 kfree(ee);
445}
446
447static void bpf_event_entry_free_rcu(struct bpf_event_entry *ee)
448{
449 call_rcu(&ee->rcu, __bpf_event_entry_free);
450}
451
452static void *perf_event_fd_array_get_ptr(struct bpf_map *map,
453 struct file *map_file, int fd)
454{
455 const struct perf_event_attr *attr;
456 struct bpf_event_entry *ee;
457 struct perf_event *event;
458 struct file *perf_file;
459
460 perf_file = perf_event_get(fd);
461 if (IS_ERR(perf_file))
462 return perf_file;
463
464 event = perf_file->private_data;
465 ee = ERR_PTR(-EINVAL);
466
467 attr = perf_event_attrs(event);
468 if (IS_ERR(attr) || attr->inherit)
469 goto err_out;
470
471 switch (attr->type) {
472 case PERF_TYPE_SOFTWARE:
473 if (attr->config != PERF_COUNT_SW_BPF_OUTPUT)
474 goto err_out;
475 /* fall-through */
476 case PERF_TYPE_RAW:
477 case PERF_TYPE_HARDWARE:
478 ee = bpf_event_entry_gen(perf_file, map_file);
479 if (ee)
480 return ee;
481 ee = ERR_PTR(-ENOMEM);
482 /* fall-through */
483 default:
484 break;
485 }
486
487err_out:
488 fput(perf_file);
489 return ee;
490}
491
492static void perf_event_fd_array_put_ptr(void *ptr)
493{
494 bpf_event_entry_free_rcu(ptr);
495}
496
497static void perf_event_fd_array_release(struct bpf_map *map,
498 struct file *map_file)
499{
500 struct bpf_array *array = container_of(map, struct bpf_array, map);
501 struct bpf_event_entry *ee;
502 int i;
503
504 rcu_read_lock();
505 for (i = 0; i < array->map.max_entries; i++) {
506 ee = READ_ONCE(array->ptrs[i]);
507 if (ee && ee->map_file == map_file)
508 fd_array_map_delete_elem(map, &i);
509 }
510 rcu_read_unlock();
511}
512
513const struct bpf_map_ops perf_event_array_map_ops = {
514 .map_alloc = fd_array_map_alloc,
515 .map_free = fd_array_map_free,
516 .map_get_next_key = array_map_get_next_key,
517 .map_lookup_elem = fd_array_map_lookup_elem,
518 .map_delete_elem = fd_array_map_delete_elem,
519 .map_fd_get_ptr = perf_event_fd_array_get_ptr,
520 .map_fd_put_ptr = perf_event_fd_array_put_ptr,
521 .map_release = perf_event_fd_array_release,
522};
523
524#ifdef CONFIG_CGROUPS
525static void *cgroup_fd_array_get_ptr(struct bpf_map *map,
526 struct file *map_file /* not used */,
527 int fd)
528{
529 return cgroup_get_from_fd(fd);
530}
531
532static void cgroup_fd_array_put_ptr(void *ptr)
533{
534 /* cgroup_put free cgrp after a rcu grace period */
535 cgroup_put(ptr);
536}
537
538static void cgroup_fd_array_free(struct bpf_map *map)
539{
540 bpf_fd_array_map_clear(map);
541 fd_array_map_free(map);
542}
543
544const struct bpf_map_ops cgroup_array_map_ops = {
545 .map_alloc = fd_array_map_alloc,
546 .map_free = cgroup_fd_array_free,
547 .map_get_next_key = array_map_get_next_key,
548 .map_lookup_elem = fd_array_map_lookup_elem,
549 .map_delete_elem = fd_array_map_delete_elem,
550 .map_fd_get_ptr = cgroup_fd_array_get_ptr,
551 .map_fd_put_ptr = cgroup_fd_array_put_ptr,
552};
553#endif
554
555static struct bpf_map *array_of_map_alloc(union bpf_attr *attr)
556{
557 struct bpf_map *map, *inner_map_meta;
558
559 inner_map_meta = bpf_map_meta_alloc(attr->inner_map_fd);
560 if (IS_ERR(inner_map_meta))
561 return inner_map_meta;
562
563 map = fd_array_map_alloc(attr);
564 if (IS_ERR(map)) {
565 bpf_map_meta_free(inner_map_meta);
566 return map;
567 }
568
569 map->inner_map_meta = inner_map_meta;
570
571 return map;
572}
573
574static void array_of_map_free(struct bpf_map *map)
575{
576 /* map->inner_map_meta is only accessed by syscall which
577 * is protected by fdget/fdput.
578 */
579 bpf_map_meta_free(map->inner_map_meta);
580 bpf_fd_array_map_clear(map);
581 fd_array_map_free(map);
582}
583
584static void *array_of_map_lookup_elem(struct bpf_map *map, void *key)
585{
586 struct bpf_map **inner_map = array_map_lookup_elem(map, key);
587
588 if (!inner_map)
589 return NULL;
590
591 return READ_ONCE(*inner_map);
592}
593
594const struct bpf_map_ops array_of_maps_map_ops = {
595 .map_alloc = array_of_map_alloc,
596 .map_free = array_of_map_free,
597 .map_get_next_key = array_map_get_next_key,
598 .map_lookup_elem = array_of_map_lookup_elem,
599 .map_delete_elem = fd_array_map_delete_elem,
600 .map_fd_get_ptr = bpf_map_fd_get_ptr,
601 .map_fd_put_ptr = bpf_map_fd_put_ptr,
602};