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1//SPDX-License-Identifier: GPL-2.0
2#include <linux/bpf-cgroup.h>
3#include <linux/bpf.h>
4#include <linux/btf.h>
5#include <linux/bug.h>
6#include <linux/filter.h>
7#include <linux/mm.h>
8#include <linux/rbtree.h>
9#include <linux/slab.h>
10#include <uapi/linux/btf.h>
11
12#ifdef CONFIG_CGROUP_BPF
13
14DEFINE_PER_CPU(struct bpf_cgroup_storage_info,
15 bpf_cgroup_storage_info[BPF_CGROUP_STORAGE_NEST_MAX]);
16
17#include "../cgroup/cgroup-internal.h"
18
19#define LOCAL_STORAGE_CREATE_FLAG_MASK \
20 (BPF_F_NUMA_NODE | BPF_F_ACCESS_MASK)
21
22struct bpf_cgroup_storage_map {
23 struct bpf_map map;
24
25 spinlock_t lock;
26 struct rb_root root;
27 struct list_head list;
28};
29
30static struct bpf_cgroup_storage_map *map_to_storage(struct bpf_map *map)
31{
32 return container_of(map, struct bpf_cgroup_storage_map, map);
33}
34
35static bool attach_type_isolated(const struct bpf_map *map)
36{
37 return map->key_size == sizeof(struct bpf_cgroup_storage_key);
38}
39
40static int bpf_cgroup_storage_key_cmp(const struct bpf_cgroup_storage_map *map,
41 const void *_key1, const void *_key2)
42{
43 if (attach_type_isolated(&map->map)) {
44 const struct bpf_cgroup_storage_key *key1 = _key1;
45 const struct bpf_cgroup_storage_key *key2 = _key2;
46
47 if (key1->cgroup_inode_id < key2->cgroup_inode_id)
48 return -1;
49 else if (key1->cgroup_inode_id > key2->cgroup_inode_id)
50 return 1;
51 else if (key1->attach_type < key2->attach_type)
52 return -1;
53 else if (key1->attach_type > key2->attach_type)
54 return 1;
55 } else {
56 const __u64 *cgroup_inode_id1 = _key1;
57 const __u64 *cgroup_inode_id2 = _key2;
58
59 if (*cgroup_inode_id1 < *cgroup_inode_id2)
60 return -1;
61 else if (*cgroup_inode_id1 > *cgroup_inode_id2)
62 return 1;
63 }
64 return 0;
65}
66
67struct bpf_cgroup_storage *
68cgroup_storage_lookup(struct bpf_cgroup_storage_map *map,
69 void *key, bool locked)
70{
71 struct rb_root *root = &map->root;
72 struct rb_node *node;
73
74 if (!locked)
75 spin_lock_bh(&map->lock);
76
77 node = root->rb_node;
78 while (node) {
79 struct bpf_cgroup_storage *storage;
80
81 storage = container_of(node, struct bpf_cgroup_storage, node);
82
83 switch (bpf_cgroup_storage_key_cmp(map, key, &storage->key)) {
84 case -1:
85 node = node->rb_left;
86 break;
87 case 1:
88 node = node->rb_right;
89 break;
90 default:
91 if (!locked)
92 spin_unlock_bh(&map->lock);
93 return storage;
94 }
95 }
96
97 if (!locked)
98 spin_unlock_bh(&map->lock);
99
100 return NULL;
101}
102
103static int cgroup_storage_insert(struct bpf_cgroup_storage_map *map,
104 struct bpf_cgroup_storage *storage)
105{
106 struct rb_root *root = &map->root;
107 struct rb_node **new = &(root->rb_node), *parent = NULL;
108
109 while (*new) {
110 struct bpf_cgroup_storage *this;
111
112 this = container_of(*new, struct bpf_cgroup_storage, node);
113
114 parent = *new;
115 switch (bpf_cgroup_storage_key_cmp(map, &storage->key, &this->key)) {
116 case -1:
117 new = &((*new)->rb_left);
118 break;
119 case 1:
120 new = &((*new)->rb_right);
121 break;
122 default:
123 return -EEXIST;
124 }
125 }
126
127 rb_link_node(&storage->node, parent, new);
128 rb_insert_color(&storage->node, root);
129
130 return 0;
131}
132
133static void *cgroup_storage_lookup_elem(struct bpf_map *_map, void *key)
134{
135 struct bpf_cgroup_storage_map *map = map_to_storage(_map);
136 struct bpf_cgroup_storage *storage;
137
138 storage = cgroup_storage_lookup(map, key, false);
139 if (!storage)
140 return NULL;
141
142 return &READ_ONCE(storage->buf)->data[0];
143}
144
145static int cgroup_storage_update_elem(struct bpf_map *map, void *key,
146 void *value, u64 flags)
147{
148 struct bpf_cgroup_storage *storage;
149 struct bpf_storage_buffer *new;
150
151 if (unlikely(flags & ~(BPF_F_LOCK | BPF_EXIST)))
152 return -EINVAL;
153
154 if (unlikely((flags & BPF_F_LOCK) &&
155 !map_value_has_spin_lock(map)))
156 return -EINVAL;
157
158 storage = cgroup_storage_lookup((struct bpf_cgroup_storage_map *)map,
159 key, false);
160 if (!storage)
161 return -ENOENT;
162
163 if (flags & BPF_F_LOCK) {
164 copy_map_value_locked(map, storage->buf->data, value, false);
165 return 0;
166 }
167
168 new = bpf_map_kmalloc_node(map, sizeof(struct bpf_storage_buffer) +
169 map->value_size,
170 __GFP_ZERO | GFP_ATOMIC | __GFP_NOWARN,
171 map->numa_node);
172 if (!new)
173 return -ENOMEM;
174
175 memcpy(&new->data[0], value, map->value_size);
176 check_and_init_map_lock(map, new->data);
177
178 new = xchg(&storage->buf, new);
179 kfree_rcu(new, rcu);
180
181 return 0;
182}
183
184int bpf_percpu_cgroup_storage_copy(struct bpf_map *_map, void *key,
185 void *value)
186{
187 struct bpf_cgroup_storage_map *map = map_to_storage(_map);
188 struct bpf_cgroup_storage *storage;
189 int cpu, off = 0;
190 u32 size;
191
192 rcu_read_lock();
193 storage = cgroup_storage_lookup(map, key, false);
194 if (!storage) {
195 rcu_read_unlock();
196 return -ENOENT;
197 }
198
199 /* per_cpu areas are zero-filled and bpf programs can only
200 * access 'value_size' of them, so copying rounded areas
201 * will not leak any kernel data
202 */
203 size = round_up(_map->value_size, 8);
204 for_each_possible_cpu(cpu) {
205 bpf_long_memcpy(value + off,
206 per_cpu_ptr(storage->percpu_buf, cpu), size);
207 off += size;
208 }
209 rcu_read_unlock();
210 return 0;
211}
212
213int bpf_percpu_cgroup_storage_update(struct bpf_map *_map, void *key,
214 void *value, u64 map_flags)
215{
216 struct bpf_cgroup_storage_map *map = map_to_storage(_map);
217 struct bpf_cgroup_storage *storage;
218 int cpu, off = 0;
219 u32 size;
220
221 if (map_flags != BPF_ANY && map_flags != BPF_EXIST)
222 return -EINVAL;
223
224 rcu_read_lock();
225 storage = cgroup_storage_lookup(map, key, false);
226 if (!storage) {
227 rcu_read_unlock();
228 return -ENOENT;
229 }
230
231 /* the user space will provide round_up(value_size, 8) bytes that
232 * will be copied into per-cpu area. bpf programs can only access
233 * value_size of it. During lookup the same extra bytes will be
234 * returned or zeros which were zero-filled by percpu_alloc,
235 * so no kernel data leaks possible
236 */
237 size = round_up(_map->value_size, 8);
238 for_each_possible_cpu(cpu) {
239 bpf_long_memcpy(per_cpu_ptr(storage->percpu_buf, cpu),
240 value + off, size);
241 off += size;
242 }
243 rcu_read_unlock();
244 return 0;
245}
246
247static int cgroup_storage_get_next_key(struct bpf_map *_map, void *key,
248 void *_next_key)
249{
250 struct bpf_cgroup_storage_map *map = map_to_storage(_map);
251 struct bpf_cgroup_storage *storage;
252
253 spin_lock_bh(&map->lock);
254
255 if (list_empty(&map->list))
256 goto enoent;
257
258 if (key) {
259 storage = cgroup_storage_lookup(map, key, true);
260 if (!storage)
261 goto enoent;
262
263 storage = list_next_entry(storage, list_map);
264 if (!storage)
265 goto enoent;
266 } else {
267 storage = list_first_entry(&map->list,
268 struct bpf_cgroup_storage, list_map);
269 }
270
271 spin_unlock_bh(&map->lock);
272
273 if (attach_type_isolated(&map->map)) {
274 struct bpf_cgroup_storage_key *next = _next_key;
275 *next = storage->key;
276 } else {
277 __u64 *next = _next_key;
278 *next = storage->key.cgroup_inode_id;
279 }
280 return 0;
281
282enoent:
283 spin_unlock_bh(&map->lock);
284 return -ENOENT;
285}
286
287static struct bpf_map *cgroup_storage_map_alloc(union bpf_attr *attr)
288{
289 int numa_node = bpf_map_attr_numa_node(attr);
290 struct bpf_cgroup_storage_map *map;
291
292 if (attr->key_size != sizeof(struct bpf_cgroup_storage_key) &&
293 attr->key_size != sizeof(__u64))
294 return ERR_PTR(-EINVAL);
295
296 if (attr->value_size == 0)
297 return ERR_PTR(-EINVAL);
298
299 if (attr->value_size > PAGE_SIZE)
300 return ERR_PTR(-E2BIG);
301
302 if (attr->map_flags & ~LOCAL_STORAGE_CREATE_FLAG_MASK ||
303 !bpf_map_flags_access_ok(attr->map_flags))
304 return ERR_PTR(-EINVAL);
305
306 if (attr->max_entries)
307 /* max_entries is not used and enforced to be 0 */
308 return ERR_PTR(-EINVAL);
309
310 map = kmalloc_node(sizeof(struct bpf_cgroup_storage_map),
311 __GFP_ZERO | GFP_USER | __GFP_ACCOUNT, numa_node);
312 if (!map)
313 return ERR_PTR(-ENOMEM);
314
315 /* copy mandatory map attributes */
316 bpf_map_init_from_attr(&map->map, attr);
317
318 spin_lock_init(&map->lock);
319 map->root = RB_ROOT;
320 INIT_LIST_HEAD(&map->list);
321
322 return &map->map;
323}
324
325static void cgroup_storage_map_free(struct bpf_map *_map)
326{
327 struct bpf_cgroup_storage_map *map = map_to_storage(_map);
328 struct list_head *storages = &map->list;
329 struct bpf_cgroup_storage *storage, *stmp;
330
331 mutex_lock(&cgroup_mutex);
332
333 list_for_each_entry_safe(storage, stmp, storages, list_map) {
334 bpf_cgroup_storage_unlink(storage);
335 bpf_cgroup_storage_free(storage);
336 }
337
338 mutex_unlock(&cgroup_mutex);
339
340 WARN_ON(!RB_EMPTY_ROOT(&map->root));
341 WARN_ON(!list_empty(&map->list));
342
343 kfree(map);
344}
345
346static int cgroup_storage_delete_elem(struct bpf_map *map, void *key)
347{
348 return -EINVAL;
349}
350
351static int cgroup_storage_check_btf(const struct bpf_map *map,
352 const struct btf *btf,
353 const struct btf_type *key_type,
354 const struct btf_type *value_type)
355{
356 if (attach_type_isolated(map)) {
357 struct btf_member *m;
358 u32 offset, size;
359
360 /* Key is expected to be of struct bpf_cgroup_storage_key type,
361 * which is:
362 * struct bpf_cgroup_storage_key {
363 * __u64 cgroup_inode_id;
364 * __u32 attach_type;
365 * };
366 */
367
368 /*
369 * Key_type must be a structure with two fields.
370 */
371 if (BTF_INFO_KIND(key_type->info) != BTF_KIND_STRUCT ||
372 BTF_INFO_VLEN(key_type->info) != 2)
373 return -EINVAL;
374
375 /*
376 * The first field must be a 64 bit integer at 0 offset.
377 */
378 m = (struct btf_member *)(key_type + 1);
379 size = sizeof_field(struct bpf_cgroup_storage_key, cgroup_inode_id);
380 if (!btf_member_is_reg_int(btf, key_type, m, 0, size))
381 return -EINVAL;
382
383 /*
384 * The second field must be a 32 bit integer at 64 bit offset.
385 */
386 m++;
387 offset = offsetof(struct bpf_cgroup_storage_key, attach_type);
388 size = sizeof_field(struct bpf_cgroup_storage_key, attach_type);
389 if (!btf_member_is_reg_int(btf, key_type, m, offset, size))
390 return -EINVAL;
391 } else {
392 u32 int_data;
393
394 /*
395 * Key is expected to be u64, which stores the cgroup_inode_id
396 */
397
398 if (BTF_INFO_KIND(key_type->info) != BTF_KIND_INT)
399 return -EINVAL;
400
401 int_data = *(u32 *)(key_type + 1);
402 if (BTF_INT_BITS(int_data) != 64 || BTF_INT_OFFSET(int_data))
403 return -EINVAL;
404 }
405
406 return 0;
407}
408
409static void cgroup_storage_seq_show_elem(struct bpf_map *map, void *key,
410 struct seq_file *m)
411{
412 enum bpf_cgroup_storage_type stype = cgroup_storage_type(map);
413 struct bpf_cgroup_storage *storage;
414 int cpu;
415
416 rcu_read_lock();
417 storage = cgroup_storage_lookup(map_to_storage(map), key, false);
418 if (!storage) {
419 rcu_read_unlock();
420 return;
421 }
422
423 btf_type_seq_show(map->btf, map->btf_key_type_id, key, m);
424 stype = cgroup_storage_type(map);
425 if (stype == BPF_CGROUP_STORAGE_SHARED) {
426 seq_puts(m, ": ");
427 btf_type_seq_show(map->btf, map->btf_value_type_id,
428 &READ_ONCE(storage->buf)->data[0], m);
429 seq_puts(m, "\n");
430 } else {
431 seq_puts(m, ": {\n");
432 for_each_possible_cpu(cpu) {
433 seq_printf(m, "\tcpu%d: ", cpu);
434 btf_type_seq_show(map->btf, map->btf_value_type_id,
435 per_cpu_ptr(storage->percpu_buf, cpu),
436 m);
437 seq_puts(m, "\n");
438 }
439 seq_puts(m, "}\n");
440 }
441 rcu_read_unlock();
442}
443
444static int cgroup_storage_map_btf_id;
445const struct bpf_map_ops cgroup_storage_map_ops = {
446 .map_alloc = cgroup_storage_map_alloc,
447 .map_free = cgroup_storage_map_free,
448 .map_get_next_key = cgroup_storage_get_next_key,
449 .map_lookup_elem = cgroup_storage_lookup_elem,
450 .map_update_elem = cgroup_storage_update_elem,
451 .map_delete_elem = cgroup_storage_delete_elem,
452 .map_check_btf = cgroup_storage_check_btf,
453 .map_seq_show_elem = cgroup_storage_seq_show_elem,
454 .map_btf_name = "bpf_cgroup_storage_map",
455 .map_btf_id = &cgroup_storage_map_btf_id,
456};
457
458int bpf_cgroup_storage_assign(struct bpf_prog_aux *aux, struct bpf_map *_map)
459{
460 enum bpf_cgroup_storage_type stype = cgroup_storage_type(_map);
461
462 if (aux->cgroup_storage[stype] &&
463 aux->cgroup_storage[stype] != _map)
464 return -EBUSY;
465
466 aux->cgroup_storage[stype] = _map;
467 return 0;
468}
469
470static size_t bpf_cgroup_storage_calculate_size(struct bpf_map *map, u32 *pages)
471{
472 size_t size;
473
474 if (cgroup_storage_type(map) == BPF_CGROUP_STORAGE_SHARED) {
475 size = sizeof(struct bpf_storage_buffer) + map->value_size;
476 *pages = round_up(sizeof(struct bpf_cgroup_storage) + size,
477 PAGE_SIZE) >> PAGE_SHIFT;
478 } else {
479 size = map->value_size;
480 *pages = round_up(round_up(size, 8) * num_possible_cpus(),
481 PAGE_SIZE) >> PAGE_SHIFT;
482 }
483
484 return size;
485}
486
487struct bpf_cgroup_storage *bpf_cgroup_storage_alloc(struct bpf_prog *prog,
488 enum bpf_cgroup_storage_type stype)
489{
490 const gfp_t gfp = __GFP_ZERO | GFP_USER;
491 struct bpf_cgroup_storage *storage;
492 struct bpf_map *map;
493 size_t size;
494 u32 pages;
495
496 map = prog->aux->cgroup_storage[stype];
497 if (!map)
498 return NULL;
499
500 size = bpf_cgroup_storage_calculate_size(map, &pages);
501
502 storage = bpf_map_kmalloc_node(map, sizeof(struct bpf_cgroup_storage),
503 gfp, map->numa_node);
504 if (!storage)
505 goto enomem;
506
507 if (stype == BPF_CGROUP_STORAGE_SHARED) {
508 storage->buf = bpf_map_kmalloc_node(map, size, gfp,
509 map->numa_node);
510 if (!storage->buf)
511 goto enomem;
512 check_and_init_map_lock(map, storage->buf->data);
513 } else {
514 storage->percpu_buf = bpf_map_alloc_percpu(map, size, 8, gfp);
515 if (!storage->percpu_buf)
516 goto enomem;
517 }
518
519 storage->map = (struct bpf_cgroup_storage_map *)map;
520
521 return storage;
522
523enomem:
524 kfree(storage);
525 return ERR_PTR(-ENOMEM);
526}
527
528static void free_shared_cgroup_storage_rcu(struct rcu_head *rcu)
529{
530 struct bpf_cgroup_storage *storage =
531 container_of(rcu, struct bpf_cgroup_storage, rcu);
532
533 kfree(storage->buf);
534 kfree(storage);
535}
536
537static void free_percpu_cgroup_storage_rcu(struct rcu_head *rcu)
538{
539 struct bpf_cgroup_storage *storage =
540 container_of(rcu, struct bpf_cgroup_storage, rcu);
541
542 free_percpu(storage->percpu_buf);
543 kfree(storage);
544}
545
546void bpf_cgroup_storage_free(struct bpf_cgroup_storage *storage)
547{
548 enum bpf_cgroup_storage_type stype;
549 struct bpf_map *map;
550
551 if (!storage)
552 return;
553
554 map = &storage->map->map;
555 stype = cgroup_storage_type(map);
556 if (stype == BPF_CGROUP_STORAGE_SHARED)
557 call_rcu(&storage->rcu, free_shared_cgroup_storage_rcu);
558 else
559 call_rcu(&storage->rcu, free_percpu_cgroup_storage_rcu);
560}
561
562void bpf_cgroup_storage_link(struct bpf_cgroup_storage *storage,
563 struct cgroup *cgroup,
564 enum bpf_attach_type type)
565{
566 struct bpf_cgroup_storage_map *map;
567
568 if (!storage)
569 return;
570
571 storage->key.attach_type = type;
572 storage->key.cgroup_inode_id = cgroup_id(cgroup);
573
574 map = storage->map;
575
576 spin_lock_bh(&map->lock);
577 WARN_ON(cgroup_storage_insert(map, storage));
578 list_add(&storage->list_map, &map->list);
579 list_add(&storage->list_cg, &cgroup->bpf.storages);
580 spin_unlock_bh(&map->lock);
581}
582
583void bpf_cgroup_storage_unlink(struct bpf_cgroup_storage *storage)
584{
585 struct bpf_cgroup_storage_map *map;
586 struct rb_root *root;
587
588 if (!storage)
589 return;
590
591 map = storage->map;
592
593 spin_lock_bh(&map->lock);
594 root = &map->root;
595 rb_erase(&storage->node, root);
596
597 list_del(&storage->list_map);
598 list_del(&storage->list_cg);
599 spin_unlock_bh(&map->lock);
600}
601
602#endif