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 
21 struct 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 
map_to_storage(struct bpf_map * map)29 static 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 
attach_type_isolated(const struct bpf_map * map)34 static bool attach_type_isolated(const struct bpf_map *map)
35 {
36 	return map->key_size == sizeof(struct bpf_cgroup_storage_key);
37 }
38 
bpf_cgroup_storage_key_cmp(const struct bpf_cgroup_storage_map * map,const void * _key1,const void * _key2)39 static 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 
66 struct bpf_cgroup_storage *
cgroup_storage_lookup(struct bpf_cgroup_storage_map * map,void * key,bool locked)67 cgroup_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 
cgroup_storage_insert(struct bpf_cgroup_storage_map * map,struct bpf_cgroup_storage * storage)102 static 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 
cgroup_storage_lookup_elem(struct bpf_map * _map,void * key)132 static 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 
cgroup_storage_update_elem(struct bpf_map * map,void * key,void * value,u64 flags)144 static 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 | __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 = bpf_map_area_alloc(sizeof(struct bpf_cgroup_storage_map), numa_node);
317 	if (!map)
318 		return ERR_PTR(-ENOMEM);
319 
320 	/* copy mandatory map attributes */
321 	bpf_map_init_from_attr(&map->map, attr);
322 
323 	spin_lock_init(&map->lock);
324 	map->root = RB_ROOT;
325 	INIT_LIST_HEAD(&map->list);
326 
327 	return &map->map;
328 }
329 
cgroup_storage_map_free(struct bpf_map * _map)330 static void cgroup_storage_map_free(struct bpf_map *_map)
331 {
332 	struct bpf_cgroup_storage_map *map = map_to_storage(_map);
333 	struct list_head *storages = &map->list;
334 	struct bpf_cgroup_storage *storage, *stmp;
335 
336 	cgroup_lock();
337 
338 	list_for_each_entry_safe(storage, stmp, storages, list_map) {
339 		bpf_cgroup_storage_unlink(storage);
340 		bpf_cgroup_storage_free(storage);
341 	}
342 
343 	cgroup_unlock();
344 
345 	WARN_ON(!RB_EMPTY_ROOT(&map->root));
346 	WARN_ON(!list_empty(&map->list));
347 
348 	bpf_map_area_free(map);
349 }
350 
cgroup_storage_delete_elem(struct bpf_map * map,void * key)351 static long cgroup_storage_delete_elem(struct bpf_map *map, void *key)
352 {
353 	return -EINVAL;
354 }
355 
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)356 static int cgroup_storage_check_btf(const struct bpf_map *map,
357 				    const struct btf *btf,
358 				    const struct btf_type *key_type,
359 				    const struct btf_type *value_type)
360 {
361 	if (attach_type_isolated(map)) {
362 		struct btf_member *m;
363 		u32 offset, size;
364 
365 		/* Key is expected to be of struct bpf_cgroup_storage_key type,
366 		 * which is:
367 		 * struct bpf_cgroup_storage_key {
368 		 *	__u64	cgroup_inode_id;
369 		 *	__u32	attach_type;
370 		 * };
371 		 */
372 
373 		/*
374 		 * Key_type must be a structure with two fields.
375 		 */
376 		if (BTF_INFO_KIND(key_type->info) != BTF_KIND_STRUCT ||
377 		    BTF_INFO_VLEN(key_type->info) != 2)
378 			return -EINVAL;
379 
380 		/*
381 		 * The first field must be a 64 bit integer at 0 offset.
382 		 */
383 		m = (struct btf_member *)(key_type + 1);
384 		size = sizeof_field(struct bpf_cgroup_storage_key, cgroup_inode_id);
385 		if (!btf_member_is_reg_int(btf, key_type, m, 0, size))
386 			return -EINVAL;
387 
388 		/*
389 		 * The second field must be a 32 bit integer at 64 bit offset.
390 		 */
391 		m++;
392 		offset = offsetof(struct bpf_cgroup_storage_key, attach_type);
393 		size = sizeof_field(struct bpf_cgroup_storage_key, attach_type);
394 		if (!btf_member_is_reg_int(btf, key_type, m, offset, size))
395 			return -EINVAL;
396 	} else {
397 		u32 int_data;
398 
399 		/*
400 		 * Key is expected to be u64, which stores the cgroup_inode_id
401 		 */
402 
403 		if (BTF_INFO_KIND(key_type->info) != BTF_KIND_INT)
404 			return -EINVAL;
405 
406 		int_data = *(u32 *)(key_type + 1);
407 		if (BTF_INT_BITS(int_data) != 64 || BTF_INT_OFFSET(int_data))
408 			return -EINVAL;
409 	}
410 
411 	return 0;
412 }
413 
cgroup_storage_seq_show_elem(struct bpf_map * map,void * key,struct seq_file * m)414 static void cgroup_storage_seq_show_elem(struct bpf_map *map, void *key,
415 					 struct seq_file *m)
416 {
417 	enum bpf_cgroup_storage_type stype;
418 	struct bpf_cgroup_storage *storage;
419 	int cpu;
420 
421 	rcu_read_lock();
422 	storage = cgroup_storage_lookup(map_to_storage(map), key, false);
423 	if (!storage) {
424 		rcu_read_unlock();
425 		return;
426 	}
427 
428 	btf_type_seq_show(map->btf, map->btf_key_type_id, key, m);
429 	stype = cgroup_storage_type(map);
430 	if (stype == BPF_CGROUP_STORAGE_SHARED) {
431 		seq_puts(m, ": ");
432 		btf_type_seq_show(map->btf, map->btf_value_type_id,
433 				  &READ_ONCE(storage->buf)->data[0], m);
434 		seq_puts(m, "\n");
435 	} else {
436 		seq_puts(m, ": {\n");
437 		for_each_possible_cpu(cpu) {
438 			seq_printf(m, "\tcpu%d: ", cpu);
439 			btf_type_seq_show(map->btf, map->btf_value_type_id,
440 					  per_cpu_ptr(storage->percpu_buf, cpu),
441 					  m);
442 			seq_puts(m, "\n");
443 		}
444 		seq_puts(m, "}\n");
445 	}
446 	rcu_read_unlock();
447 }
448 
cgroup_storage_map_usage(const struct bpf_map * map)449 static u64 cgroup_storage_map_usage(const struct bpf_map *map)
450 {
451 	/* Currently the dynamically allocated elements are not counted. */
452 	return sizeof(struct bpf_cgroup_storage_map);
453 }
454 
455 BTF_ID_LIST_SINGLE(cgroup_storage_map_btf_ids, struct,
456 		   bpf_cgroup_storage_map)
457 const struct bpf_map_ops cgroup_storage_map_ops = {
458 	.map_alloc = cgroup_storage_map_alloc,
459 	.map_free = cgroup_storage_map_free,
460 	.map_get_next_key = cgroup_storage_get_next_key,
461 	.map_lookup_elem = cgroup_storage_lookup_elem,
462 	.map_update_elem = cgroup_storage_update_elem,
463 	.map_delete_elem = cgroup_storage_delete_elem,
464 	.map_check_btf = cgroup_storage_check_btf,
465 	.map_seq_show_elem = cgroup_storage_seq_show_elem,
466 	.map_mem_usage = cgroup_storage_map_usage,
467 	.map_btf_id = &cgroup_storage_map_btf_ids[0],
468 };
469 
bpf_cgroup_storage_assign(struct bpf_prog_aux * aux,struct bpf_map * _map)470 int bpf_cgroup_storage_assign(struct bpf_prog_aux *aux, struct bpf_map *_map)
471 {
472 	enum bpf_cgroup_storage_type stype = cgroup_storage_type(_map);
473 
474 	if (aux->cgroup_storage[stype] &&
475 	    aux->cgroup_storage[stype] != _map)
476 		return -EBUSY;
477 
478 	aux->cgroup_storage[stype] = _map;
479 	return 0;
480 }
481 
bpf_cgroup_storage_calculate_size(struct bpf_map * map,u32 * pages)482 static size_t bpf_cgroup_storage_calculate_size(struct bpf_map *map, u32 *pages)
483 {
484 	size_t size;
485 
486 	if (cgroup_storage_type(map) == BPF_CGROUP_STORAGE_SHARED) {
487 		size = sizeof(struct bpf_storage_buffer) + map->value_size;
488 		*pages = round_up(sizeof(struct bpf_cgroup_storage) + size,
489 				  PAGE_SIZE) >> PAGE_SHIFT;
490 	} else {
491 		size = map->value_size;
492 		*pages = round_up(round_up(size, 8) * num_possible_cpus(),
493 				  PAGE_SIZE) >> PAGE_SHIFT;
494 	}
495 
496 	return size;
497 }
498 
bpf_cgroup_storage_alloc(struct bpf_prog * prog,enum bpf_cgroup_storage_type stype)499 struct bpf_cgroup_storage *bpf_cgroup_storage_alloc(struct bpf_prog *prog,
500 					enum bpf_cgroup_storage_type stype)
501 {
502 	const gfp_t gfp = __GFP_ZERO | GFP_USER;
503 	struct bpf_cgroup_storage *storage;
504 	struct bpf_map *map;
505 	size_t size;
506 	u32 pages;
507 
508 	map = prog->aux->cgroup_storage[stype];
509 	if (!map)
510 		return NULL;
511 
512 	size = bpf_cgroup_storage_calculate_size(map, &pages);
513 
514 	storage = bpf_map_kmalloc_node(map, sizeof(struct bpf_cgroup_storage),
515 				       gfp, map->numa_node);
516 	if (!storage)
517 		goto enomem;
518 
519 	if (stype == BPF_CGROUP_STORAGE_SHARED) {
520 		storage->buf = bpf_map_kmalloc_node(map, size, gfp,
521 						    map->numa_node);
522 		if (!storage->buf)
523 			goto enomem;
524 		check_and_init_map_value(map, storage->buf->data);
525 	} else {
526 		storage->percpu_buf = bpf_map_alloc_percpu(map, size, 8, gfp);
527 		if (!storage->percpu_buf)
528 			goto enomem;
529 	}
530 
531 	storage->map = (struct bpf_cgroup_storage_map *)map;
532 
533 	return storage;
534 
535 enomem:
536 	kfree(storage);
537 	return ERR_PTR(-ENOMEM);
538 }
539 
free_shared_cgroup_storage_rcu(struct rcu_head * rcu)540 static void free_shared_cgroup_storage_rcu(struct rcu_head *rcu)
541 {
542 	struct bpf_cgroup_storage *storage =
543 		container_of(rcu, struct bpf_cgroup_storage, rcu);
544 
545 	kfree(storage->buf);
546 	kfree(storage);
547 }
548 
free_percpu_cgroup_storage_rcu(struct rcu_head * rcu)549 static void free_percpu_cgroup_storage_rcu(struct rcu_head *rcu)
550 {
551 	struct bpf_cgroup_storage *storage =
552 		container_of(rcu, struct bpf_cgroup_storage, rcu);
553 
554 	free_percpu(storage->percpu_buf);
555 	kfree(storage);
556 }
557 
bpf_cgroup_storage_free(struct bpf_cgroup_storage * storage)558 void bpf_cgroup_storage_free(struct bpf_cgroup_storage *storage)
559 {
560 	enum bpf_cgroup_storage_type stype;
561 	struct bpf_map *map;
562 
563 	if (!storage)
564 		return;
565 
566 	map = &storage->map->map;
567 	stype = cgroup_storage_type(map);
568 	if (stype == BPF_CGROUP_STORAGE_SHARED)
569 		call_rcu(&storage->rcu, free_shared_cgroup_storage_rcu);
570 	else
571 		call_rcu(&storage->rcu, free_percpu_cgroup_storage_rcu);
572 }
573 
bpf_cgroup_storage_link(struct bpf_cgroup_storage * storage,struct cgroup * cgroup,enum bpf_attach_type type)574 void bpf_cgroup_storage_link(struct bpf_cgroup_storage *storage,
575 			     struct cgroup *cgroup,
576 			     enum bpf_attach_type type)
577 {
578 	struct bpf_cgroup_storage_map *map;
579 
580 	if (!storage)
581 		return;
582 
583 	storage->key.attach_type = type;
584 	storage->key.cgroup_inode_id = cgroup_id(cgroup);
585 
586 	map = storage->map;
587 
588 	spin_lock_bh(&map->lock);
589 	WARN_ON(cgroup_storage_insert(map, storage));
590 	list_add(&storage->list_map, &map->list);
591 	list_add(&storage->list_cg, &cgroup->bpf.storages);
592 	spin_unlock_bh(&map->lock);
593 }
594 
bpf_cgroup_storage_unlink(struct bpf_cgroup_storage * storage)595 void bpf_cgroup_storage_unlink(struct bpf_cgroup_storage *storage)
596 {
597 	struct bpf_cgroup_storage_map *map;
598 	struct rb_root *root;
599 
600 	if (!storage)
601 		return;
602 
603 	map = storage->map;
604 
605 	spin_lock_bh(&map->lock);
606 	root = &map->root;
607 	rb_erase(&storage->node, root);
608 
609 	list_del(&storage->list_map);
610 	list_del(&storage->list_cg);
611 	spin_unlock_bh(&map->lock);
612 }
613 
614 #endif
615