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