projects/linux·blob v4.8-rc1 · refs

582 lines · 14.4 KiB

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