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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/bpf_local_storage.h>
5#include <linux/btf.h>
6#include <linux/bug.h>
7#include <linux/filter.h>
8#include <linux/mm.h>
9#include <linux/rbtree.h>
10#include <linux/slab.h>
11#include <uapi/linux/btf.h>
12#include <linux/btf_ids.h>
13
14#ifdef CONFIG_CGROUP_BPF
15
16#include "../cgroup/cgroup-internal.h"
17
18#define LOCAL_STORAGE_CREATE_FLAG_MASK \
19 (BPF_F_NUMA_NODE | BPF_F_ACCESS_MASK)
20
21struct bpf_cgroup_storage_map {
22 struct bpf_map map;
23
24 spinlock_t lock;
25 struct rb_root root;
26 struct list_head list;
27};
28
29static struct bpf_cgroup_storage_map *map_to_storage(struct bpf_map *map)
30{
31 return container_of(map, struct bpf_cgroup_storage_map, map);
32}
33
34static bool attach_type_isolated(const struct bpf_map *map)
35{
36 return map->key_size == sizeof(struct bpf_cgroup_storage_key);
37}
38
39static int bpf_cgroup_storage_key_cmp(const struct bpf_cgroup_storage_map *map,
40 const void *_key1, const void *_key2)
41{
42 if (attach_type_isolated(&map->map)) {
43 const struct bpf_cgroup_storage_key *key1 = _key1;
44 const struct bpf_cgroup_storage_key *key2 = _key2;
45
46 if (key1->cgroup_inode_id < key2->cgroup_inode_id)
47 return -1;
48 else if (key1->cgroup_inode_id > key2->cgroup_inode_id)
49 return 1;
50 else if (key1->attach_type < key2->attach_type)
51 return -1;
52 else if (key1->attach_type > key2->attach_type)
53 return 1;
54 } else {
55 const __u64 *cgroup_inode_id1 = _key1;
56 const __u64 *cgroup_inode_id2 = _key2;
57
58 if (*cgroup_inode_id1 < *cgroup_inode_id2)
59 return -1;
60 else if (*cgroup_inode_id1 > *cgroup_inode_id2)
61 return 1;
62 }
63 return 0;
64}
65
66struct bpf_cgroup_storage *
67cgroup_storage_lookup(struct bpf_cgroup_storage_map *map,
68 void *key, bool locked)
69{
70 struct rb_root *root = &map->root;
71 struct rb_node *node;
72
73 if (!locked)
74 spin_lock_bh(&map->lock);
75
76 node = root->rb_node;
77 while (node) {
78 struct bpf_cgroup_storage *storage;
79
80 storage = container_of(node, struct bpf_cgroup_storage, node);
81
82 switch (bpf_cgroup_storage_key_cmp(map, key, &storage->key)) {
83 case -1:
84 node = node->rb_left;
85 break;
86 case 1:
87 node = node->rb_right;
88 break;
89 default:
90 if (!locked)
91 spin_unlock_bh(&map->lock);
92 return storage;
93 }
94 }
95
96 if (!locked)
97 spin_unlock_bh(&map->lock);
98
99 return NULL;
100}
101
102static int cgroup_storage_insert(struct bpf_cgroup_storage_map *map,
103 struct bpf_cgroup_storage *storage)
104{
105 struct rb_root *root = &map->root;
106 struct rb_node **new = &(root->rb_node), *parent = NULL;
107
108 while (*new) {
109 struct bpf_cgroup_storage *this;
110
111 this = container_of(*new, struct bpf_cgroup_storage, node);
112
113 parent = *new;
114 switch (bpf_cgroup_storage_key_cmp(map, &storage->key, &this->key)) {
115 case -1:
116 new = &((*new)->rb_left);
117 break;
118 case 1:
119 new = &((*new)->rb_right);
120 break;
121 default:
122 return -EEXIST;
123 }
124 }
125
126 rb_link_node(&storage->node, parent, new);
127 rb_insert_color(&storage->node, root);
128
129 return 0;
130}
131
132static void *cgroup_storage_lookup_elem(struct bpf_map *_map, void *key)
133{
134 struct bpf_cgroup_storage_map *map = map_to_storage(_map);
135 struct bpf_cgroup_storage *storage;
136
137 storage = cgroup_storage_lookup(map, key, false);
138 if (!storage)
139 return NULL;
140
141 return &READ_ONCE(storage->buf)->data[0];
142}
143
144static long cgroup_storage_update_elem(struct bpf_map *map, void *key,
145 void *value, u64 flags)
146{
147 struct bpf_cgroup_storage *storage;
148 struct bpf_storage_buffer *new;
149
150 if (unlikely(flags & ~(BPF_F_LOCK | BPF_EXIST)))
151 return -EINVAL;
152
153 if (unlikely((flags & BPF_F_LOCK) &&
154 !btf_record_has_field(map->record, BPF_SPIN_LOCK)))
155 return -EINVAL;
156
157 storage = cgroup_storage_lookup((struct bpf_cgroup_storage_map *)map,
158 key, false);
159 if (!storage)
160 return -ENOENT;
161
162 if (flags & BPF_F_LOCK) {
163 copy_map_value_locked(map, storage->buf->data, value, false);
164 return 0;
165 }
166
167 new = bpf_map_kmalloc_node(map, struct_size(new, data, map->value_size),
168 __GFP_ZERO | GFP_NOWAIT,
169 map->numa_node);
170 if (!new)
171 return -ENOMEM;
172
173 memcpy(&new->data[0], value, map->value_size);
174 check_and_init_map_value(map, new->data);
175
176 new = xchg(&storage->buf, new);
177 kfree_rcu(new, rcu);
178
179 return 0;
180}
181
182int bpf_percpu_cgroup_storage_copy(struct bpf_map *_map, void *key,
183 void *value, u64 map_flags)
184{
185 struct bpf_cgroup_storage_map *map = map_to_storage(_map);
186 struct bpf_cgroup_storage *storage;
187 int cpu, off = 0;
188 u32 size;
189
190 rcu_read_lock();
191 storage = cgroup_storage_lookup(map, key, false);
192 if (!storage) {
193 rcu_read_unlock();
194 return -ENOENT;
195 }
196
197 /* per_cpu areas are zero-filled and bpf programs can only
198 * access 'value_size' of them, so copying rounded areas
199 * will not leak any kernel data
200 */
201 if (map_flags & BPF_F_CPU) {
202 cpu = map_flags >> 32;
203 copy_map_value(_map, value, per_cpu_ptr(storage->percpu_buf, cpu));
204 goto unlock;
205 }
206 size = round_up(_map->value_size, 8);
207 for_each_possible_cpu(cpu) {
208 copy_map_value_long(_map, value + off, per_cpu_ptr(storage->percpu_buf, cpu));
209 off += size;
210 }
211unlock:
212 rcu_read_unlock();
213 return 0;
214}
215
216int bpf_percpu_cgroup_storage_update(struct bpf_map *_map, void *key,
217 void *value, u64 map_flags)
218{
219 struct bpf_cgroup_storage_map *map = map_to_storage(_map);
220 struct bpf_cgroup_storage *storage;
221 void *val;
222 u32 size;
223 int cpu, off = 0;
224
225 if ((u32)map_flags & ~(BPF_ANY | BPF_EXIST | BPF_F_CPU | BPF_F_ALL_CPUS))
226 return -EINVAL;
227
228 rcu_read_lock();
229 storage = cgroup_storage_lookup(map, key, false);
230 if (!storage) {
231 rcu_read_unlock();
232 return -ENOENT;
233 }
234
235 /* the user space will provide round_up(value_size, 8) bytes that
236 * will be copied into per-cpu area. bpf programs can only access
237 * value_size of it. During lookup the same extra bytes will be
238 * returned or zeros which were zero-filled by percpu_alloc,
239 * so no kernel data leaks possible
240 */
241 if (map_flags & BPF_F_CPU) {
242 cpu = map_flags >> 32;
243 copy_map_value(_map, per_cpu_ptr(storage->percpu_buf, cpu), value);
244 goto unlock;
245 }
246 size = round_up(_map->value_size, 8);
247 for_each_possible_cpu(cpu) {
248 val = (map_flags & BPF_F_ALL_CPUS) ? value : value + off;
249 copy_map_value(_map, per_cpu_ptr(storage->percpu_buf, cpu), val);
250 off += size;
251 }
252unlock:
253 rcu_read_unlock();
254 return 0;
255}
256
257static int cgroup_storage_get_next_key(struct bpf_map *_map, void *key,
258 void *_next_key)
259{
260 struct bpf_cgroup_storage_map *map = map_to_storage(_map);
261 struct bpf_cgroup_storage *storage;
262
263 spin_lock_bh(&map->lock);
264
265 if (list_empty(&map->list))
266 goto enoent;
267
268 if (key) {
269 storage = cgroup_storage_lookup(map, key, true);
270 if (!storage)
271 goto enoent;
272
273 storage = list_next_entry(storage, list_map);
274 if (list_entry_is_head(storage, &map->list, list_map))
275 goto enoent;
276 } else {
277 storage = list_first_entry(&map->list,
278 struct bpf_cgroup_storage, list_map);
279 }
280
281 spin_unlock_bh(&map->lock);
282
283 if (attach_type_isolated(&map->map)) {
284 struct bpf_cgroup_storage_key *next = _next_key;
285 *next = storage->key;
286 } else {
287 __u64 *next = _next_key;
288 *next = storage->key.cgroup_inode_id;
289 }
290 return 0;
291
292enoent:
293 spin_unlock_bh(&map->lock);
294 return -ENOENT;
295}
296
297static struct bpf_map *cgroup_storage_map_alloc(union bpf_attr *attr)
298{
299 __u32 max_value_size = BPF_LOCAL_STORAGE_MAX_VALUE_SIZE;
300 int numa_node = bpf_map_attr_numa_node(attr);
301 struct bpf_cgroup_storage_map *map;
302
303 /* percpu is bound by PCPU_MIN_UNIT_SIZE, non-percu
304 * is the same as other local storages.
305 */
306 if (attr->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE)
307 max_value_size = min_t(__u32, max_value_size,
308 PCPU_MIN_UNIT_SIZE);
309
310 if (attr->key_size != sizeof(struct bpf_cgroup_storage_key) &&
311 attr->key_size != sizeof(__u64))
312 return ERR_PTR(-EINVAL);
313
314 if (attr->value_size == 0)
315 return ERR_PTR(-EINVAL);
316
317 if (attr->value_size > max_value_size)
318 return ERR_PTR(-E2BIG);
319
320 if (attr->map_flags & ~LOCAL_STORAGE_CREATE_FLAG_MASK ||
321 !bpf_map_flags_access_ok(attr->map_flags))
322 return ERR_PTR(-EINVAL);
323
324 if (attr->max_entries)
325 /* max_entries is not used and enforced to be 0 */
326 return ERR_PTR(-EINVAL);
327
328 map = bpf_map_area_alloc(sizeof(struct bpf_cgroup_storage_map), numa_node);
329 if (!map)
330 return ERR_PTR(-ENOMEM);
331
332 /* copy mandatory map attributes */
333 bpf_map_init_from_attr(&map->map, attr);
334
335 spin_lock_init(&map->lock);
336 map->root = RB_ROOT;
337 INIT_LIST_HEAD(&map->list);
338
339 return &map->map;
340}
341
342static void cgroup_storage_map_free(struct bpf_map *_map)
343{
344 struct bpf_cgroup_storage_map *map = map_to_storage(_map);
345 struct list_head *storages = &map->list;
346 struct bpf_cgroup_storage *storage, *stmp;
347
348 cgroup_lock();
349
350 list_for_each_entry_safe(storage, stmp, storages, list_map) {
351 bpf_cgroup_storage_unlink(storage);
352 bpf_cgroup_storage_free(storage);
353 }
354
355 cgroup_unlock();
356
357 WARN_ON(!RB_EMPTY_ROOT(&map->root));
358 WARN_ON(!list_empty(&map->list));
359
360 bpf_map_area_free(map);
361}
362
363static long cgroup_storage_delete_elem(struct bpf_map *map, void *key)
364{
365 return -EINVAL;
366}
367
368static int cgroup_storage_check_btf(struct bpf_map *map,
369 const struct btf *btf,
370 const struct btf_type *key_type,
371 const struct btf_type *value_type)
372{
373 if (attach_type_isolated(map)) {
374 struct btf_member *m;
375 u32 offset, size;
376
377 /* Key is expected to be of struct bpf_cgroup_storage_key type,
378 * which is:
379 * struct bpf_cgroup_storage_key {
380 * __u64 cgroup_inode_id;
381 * __u32 attach_type;
382 * };
383 */
384
385 /*
386 * Key_type must be a structure with two fields.
387 */
388 if (BTF_INFO_KIND(key_type->info) != BTF_KIND_STRUCT ||
389 BTF_INFO_VLEN(key_type->info) != 2)
390 return -EINVAL;
391
392 /*
393 * The first field must be a 64 bit integer at 0 offset.
394 */
395 m = (struct btf_member *)(key_type + 1);
396 size = sizeof_field(struct bpf_cgroup_storage_key, cgroup_inode_id);
397 if (!btf_member_is_reg_int(btf, key_type, m, 0, size))
398 return -EINVAL;
399
400 /*
401 * The second field must be a 32 bit integer at 64 bit offset.
402 */
403 m++;
404 offset = offsetof(struct bpf_cgroup_storage_key, attach_type);
405 size = sizeof_field(struct bpf_cgroup_storage_key, attach_type);
406 if (!btf_member_is_reg_int(btf, key_type, m, offset, size))
407 return -EINVAL;
408 } else {
409 /*
410 * Key is expected to be u64, which stores the cgroup_inode_id
411 */
412 if (!btf_type_is_i64(key_type))
413 return -EINVAL;
414 }
415
416 return 0;
417}
418
419static void cgroup_storage_seq_show_elem(struct bpf_map *map, void *key,
420 struct seq_file *m)
421{
422 enum bpf_cgroup_storage_type stype;
423 struct bpf_cgroup_storage *storage;
424 int cpu;
425
426 rcu_read_lock();
427 storage = cgroup_storage_lookup(map_to_storage(map), key, false);
428 if (!storage) {
429 rcu_read_unlock();
430 return;
431 }
432
433 btf_type_seq_show(map->btf, map->btf_key_type_id, key, m);
434 stype = cgroup_storage_type(map);
435 if (stype == BPF_CGROUP_STORAGE_SHARED) {
436 seq_puts(m, ": ");
437 btf_type_seq_show(map->btf, map->btf_value_type_id,
438 &READ_ONCE(storage->buf)->data[0], m);
439 seq_putc(m, '\n');
440 } else {
441 seq_puts(m, ": {\n");
442 for_each_possible_cpu(cpu) {
443 seq_printf(m, "\tcpu%d: ", cpu);
444 btf_type_seq_show(map->btf, map->btf_value_type_id,
445 per_cpu_ptr(storage->percpu_buf, cpu),
446 m);
447 seq_putc(m, '\n');
448 }
449 seq_puts(m, "}\n");
450 }
451 rcu_read_unlock();
452}
453
454static u64 cgroup_storage_map_usage(const struct bpf_map *map)
455{
456 /* Currently the dynamically allocated elements are not counted. */
457 return sizeof(struct bpf_cgroup_storage_map);
458}
459
460BTF_ID_LIST_SINGLE(cgroup_storage_map_btf_ids, struct,
461 bpf_cgroup_storage_map)
462const struct bpf_map_ops cgroup_storage_map_ops = {
463 .map_alloc = cgroup_storage_map_alloc,
464 .map_free = cgroup_storage_map_free,
465 .map_get_next_key = cgroup_storage_get_next_key,
466 .map_lookup_elem = cgroup_storage_lookup_elem,
467 .map_update_elem = cgroup_storage_update_elem,
468 .map_delete_elem = cgroup_storage_delete_elem,
469 .map_check_btf = cgroup_storage_check_btf,
470 .map_seq_show_elem = cgroup_storage_seq_show_elem,
471 .map_mem_usage = cgroup_storage_map_usage,
472 .map_btf_id = &cgroup_storage_map_btf_ids[0],
473};
474
475int bpf_cgroup_storage_assign(struct bpf_prog_aux *aux, struct bpf_map *_map)
476{
477 enum bpf_cgroup_storage_type stype = cgroup_storage_type(_map);
478
479 if (aux->cgroup_storage[stype] &&
480 aux->cgroup_storage[stype] != _map)
481 return -EBUSY;
482
483 aux->cgroup_storage[stype] = _map;
484 return 0;
485}
486
487static size_t bpf_cgroup_storage_calculate_size(struct bpf_map *map, u32 *pages)
488{
489 size_t size;
490
491 if (cgroup_storage_type(map) == BPF_CGROUP_STORAGE_SHARED) {
492 size = sizeof(struct bpf_storage_buffer) + map->value_size;
493 *pages = round_up(sizeof(struct bpf_cgroup_storage) + size,
494 PAGE_SIZE) >> PAGE_SHIFT;
495 } else {
496 size = map->value_size;
497 *pages = round_up(round_up(size, 8) * num_possible_cpus(),
498 PAGE_SIZE) >> PAGE_SHIFT;
499 }
500
501 return size;
502}
503
504struct bpf_cgroup_storage *bpf_cgroup_storage_alloc(struct bpf_prog *prog,
505 enum bpf_cgroup_storage_type stype)
506{
507 const gfp_t gfp = __GFP_ZERO | GFP_USER;
508 struct bpf_cgroup_storage *storage;
509 struct bpf_map *map;
510 size_t size;
511 u32 pages;
512
513 map = prog->aux->cgroup_storage[stype];
514 if (!map)
515 return NULL;
516
517 size = bpf_cgroup_storage_calculate_size(map, &pages);
518
519 storage = bpf_map_kmalloc_node(map, sizeof(struct bpf_cgroup_storage),
520 gfp, map->numa_node);
521 if (!storage)
522 goto enomem;
523
524 if (stype == BPF_CGROUP_STORAGE_SHARED) {
525 storage->buf = bpf_map_kmalloc_node(map, size, gfp,
526 map->numa_node);
527 if (!storage->buf)
528 goto enomem;
529 check_and_init_map_value(map, storage->buf->data);
530 } else {
531 storage->percpu_buf = bpf_map_alloc_percpu(map, size, 8, gfp);
532 if (!storage->percpu_buf)
533 goto enomem;
534 }
535
536 storage->map = (struct bpf_cgroup_storage_map *)map;
537
538 return storage;
539
540enomem:
541 kfree(storage);
542 return ERR_PTR(-ENOMEM);
543}
544
545static void free_shared_cgroup_storage_rcu(struct rcu_head *rcu)
546{
547 struct bpf_cgroup_storage *storage =
548 container_of(rcu, struct bpf_cgroup_storage, rcu);
549
550 kfree(storage->buf);
551 kfree(storage);
552}
553
554static void free_percpu_cgroup_storage_rcu(struct rcu_head *rcu)
555{
556 struct bpf_cgroup_storage *storage =
557 container_of(rcu, struct bpf_cgroup_storage, rcu);
558
559 free_percpu(storage->percpu_buf);
560 kfree(storage);
561}
562
563void bpf_cgroup_storage_free(struct bpf_cgroup_storage *storage)
564{
565 enum bpf_cgroup_storage_type stype;
566 struct bpf_map *map;
567
568 if (!storage)
569 return;
570
571 map = &storage->map->map;
572 stype = cgroup_storage_type(map);
573 if (stype == BPF_CGROUP_STORAGE_SHARED)
574 call_rcu(&storage->rcu, free_shared_cgroup_storage_rcu);
575 else
576 call_rcu(&storage->rcu, free_percpu_cgroup_storage_rcu);
577}
578
579void bpf_cgroup_storage_link(struct bpf_cgroup_storage *storage,
580 struct cgroup *cgroup,
581 enum bpf_attach_type type)
582{
583 struct bpf_cgroup_storage_map *map;
584
585 if (!storage)
586 return;
587
588 storage->key.attach_type = type;
589 storage->key.cgroup_inode_id = cgroup_id(cgroup);
590
591 map = storage->map;
592
593 spin_lock_bh(&map->lock);
594 WARN_ON(cgroup_storage_insert(map, storage));
595 list_add(&storage->list_map, &map->list);
596 list_add(&storage->list_cg, &cgroup->bpf.storages);
597 spin_unlock_bh(&map->lock);
598}
599
600void bpf_cgroup_storage_unlink(struct bpf_cgroup_storage *storage)
601{
602 struct bpf_cgroup_storage_map *map;
603 struct rb_root *root;
604
605 if (!storage)
606 return;
607
608 map = storage->map;
609
610 spin_lock_bh(&map->lock);
611 root = &map->root;
612 rb_erase(&storage->node, root);
613
614 list_del(&storage->list_map);
615 list_del(&storage->list_cg);
616 spin_unlock_bh(&map->lock);
617}
618
619#endif