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