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net/sctp: Always set scope_id in sctp_inet6_skb_msgname
[cris-mirror.git] / kernel / bpf / hashtab.c
blobe469e05c8e83bc3256378644e3f3c26555651261
1 /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
2 * Copyright (c) 2016 Facebook
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of version 2 of the GNU General Public
6 * License as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 */
13 #include <linux/bpf.h>
14 #include <linux/jhash.h>
15 #include <linux/filter.h>
16 #include <linux/rculist_nulls.h>
17 #include "percpu_freelist.h"
18 #include "bpf_lru_list.h"
19 #include "map_in_map.h"
20
21 #define HTAB_CREATE_FLAG_MASK \
22 (BPF_F_NO_PREALLOC | BPF_F_NO_COMMON_LRU | BPF_F_NUMA_NODE | \
23 BPF_F_RDONLY | BPF_F_WRONLY)
24
25 struct bucket {
26 struct hlist_nulls_head head;
27 raw_spinlock_t lock;
28 };
29
30 struct bpf_htab {
31 struct bpf_map map;
32 struct bucket *buckets;
33 void *elems;
34 union {
35 struct pcpu_freelist freelist;
36 struct bpf_lru lru;
37 };
38 struct htab_elem *__percpu *extra_elems;
39 atomic_t count; /* number of elements in this hashtable */
40 u32 n_buckets; /* number of hash buckets */
41 u32 elem_size; /* size of each element in bytes */
42 };
43
44 /* each htab element is struct htab_elem + key + value */
45 struct htab_elem {
46 union {
47 struct hlist_nulls_node hash_node;
48 struct {
49 void *padding;
50 union {
51 struct bpf_htab *htab;
52 struct pcpu_freelist_node fnode;
53 };
54 };
55 };
56 union {
57 struct rcu_head rcu;
58 struct bpf_lru_node lru_node;
59 };
60 u32 hash;
61 char key[0] __aligned(8);
62 };
63
64 static bool htab_lru_map_delete_node(void *arg, struct bpf_lru_node *node);
65
66 static bool htab_is_lru(const struct bpf_htab *htab)
67 {
68 return htab->map.map_type == BPF_MAP_TYPE_LRU_HASH ||
69 htab->map.map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH;
70 }
71
72 static bool htab_is_percpu(const struct bpf_htab *htab)
73 {
74 return htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH ||
75 htab->map.map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH;
76 }
77
78 static bool htab_is_prealloc(const struct bpf_htab *htab)
79 {
80 return !(htab->map.map_flags & BPF_F_NO_PREALLOC);
81 }
82
83 static inline void htab_elem_set_ptr(struct htab_elem *l, u32 key_size,
84 void __percpu *pptr)
85 {
86 *(void __percpu **)(l->key + key_size) = pptr;
87 }
88
89 static inline void __percpu *htab_elem_get_ptr(struct htab_elem *l, u32 key_size)
90 {
91 return *(void __percpu **)(l->key + key_size);
92 }
93
94 static void *fd_htab_map_get_ptr(const struct bpf_map *map, struct htab_elem *l)
95 {
96 return *(void **)(l->key + roundup(map->key_size, 8));
97 }
98
99 static struct htab_elem *get_htab_elem(struct bpf_htab *htab, int i)
100 {
101 return (struct htab_elem *) (htab->elems + i * htab->elem_size);
102 }
103
104 static void htab_free_elems(struct bpf_htab *htab)
105 {
106 int i;
107
108 if (!htab_is_percpu(htab))
109 goto free_elems;
110
111 for (i = 0; i < htab->map.max_entries; i++) {
112 void __percpu *pptr;
113
114 pptr = htab_elem_get_ptr(get_htab_elem(htab, i),
115 htab->map.key_size);
116 free_percpu(pptr);
117 }
118 free_elems:
119 bpf_map_area_free(htab->elems);
120 }
121
122 static struct htab_elem *prealloc_lru_pop(struct bpf_htab *htab, void *key,
123 u32 hash)
124 {
125 struct bpf_lru_node *node = bpf_lru_pop_free(&htab->lru, hash);
126 struct htab_elem *l;
127
128 if (node) {
129 l = container_of(node, struct htab_elem, lru_node);
130 memcpy(l->key, key, htab->map.key_size);
131 return l;
132 }
133
134 return NULL;
135 }
136
137 static int prealloc_init(struct bpf_htab *htab)
138 {
139 u32 num_entries = htab->map.max_entries;
140 int err = -ENOMEM, i;
141
142 if (!htab_is_percpu(htab) && !htab_is_lru(htab))
143 num_entries += num_possible_cpus();
144
145 htab->elems = bpf_map_area_alloc(htab->elem_size * num_entries,
146 htab->map.numa_node);
147 if (!htab->elems)
148 return -ENOMEM;
149
150 if (!htab_is_percpu(htab))
151 goto skip_percpu_elems;
152
153 for (i = 0; i < num_entries; i++) {
154 u32 size = round_up(htab->map.value_size, 8);
155 void __percpu *pptr;
156
157 pptr = __alloc_percpu_gfp(size, 8, GFP_USER | __GFP_NOWARN);
158 if (!pptr)
159 goto free_elems;
160 htab_elem_set_ptr(get_htab_elem(htab, i), htab->map.key_size,
161 pptr);
162 }
163
164 skip_percpu_elems:
165 if (htab_is_lru(htab))
166 err = bpf_lru_init(&htab->lru,
167 htab->map.map_flags & BPF_F_NO_COMMON_LRU,
168 offsetof(struct htab_elem, hash) -
169 offsetof(struct htab_elem, lru_node),
170 htab_lru_map_delete_node,
171 htab);
172 else
173 err = pcpu_freelist_init(&htab->freelist);
174
175 if (err)
176 goto free_elems;
177
178 if (htab_is_lru(htab))
179 bpf_lru_populate(&htab->lru, htab->elems,
180 offsetof(struct htab_elem, lru_node),
181 htab->elem_size, num_entries);
182 else
183 pcpu_freelist_populate(&htab->freelist,
184 htab->elems + offsetof(struct htab_elem, fnode),
185 htab->elem_size, num_entries);
186
187 return 0;
188
189 free_elems:
190 htab_free_elems(htab);
191 return err;
192 }
193
194 static void prealloc_destroy(struct bpf_htab *htab)
195 {
196 htab_free_elems(htab);
197
198 if (htab_is_lru(htab))
199 bpf_lru_destroy(&htab->lru);
200 else
201 pcpu_freelist_destroy(&htab->freelist);
202 }
203
204 static int alloc_extra_elems(struct bpf_htab *htab)
205 {
206 struct htab_elem *__percpu *pptr, *l_new;
207 struct pcpu_freelist_node *l;
208 int cpu;
209
210 pptr = __alloc_percpu_gfp(sizeof(struct htab_elem *), 8,
211 GFP_USER | __GFP_NOWARN);
212 if (!pptr)
213 return -ENOMEM;
214
215 for_each_possible_cpu(cpu) {
216 l = pcpu_freelist_pop(&htab->freelist);
217 /* pop will succeed, since prealloc_init()
218 * preallocated extra num_possible_cpus elements
219 */
220 l_new = container_of(l, struct htab_elem, fnode);
221 *per_cpu_ptr(pptr, cpu) = l_new;
222 }
223 htab->extra_elems = pptr;
224 return 0;
225 }
226
227 /* Called from syscall */
228 static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
229 {
230 bool percpu = (attr->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
231 attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
232 bool lru = (attr->map_type == BPF_MAP_TYPE_LRU_HASH ||
233 attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
234 /* percpu_lru means each cpu has its own LRU list.
235 * it is different from BPF_MAP_TYPE_PERCPU_HASH where
236 * the map's value itself is percpu. percpu_lru has
237 * nothing to do with the map's value.
238 */
239 bool percpu_lru = (attr->map_flags & BPF_F_NO_COMMON_LRU);
240 bool prealloc = !(attr->map_flags & BPF_F_NO_PREALLOC);
241 int numa_node = bpf_map_attr_numa_node(attr);
242 struct bpf_htab *htab;
243 int err, i;
244 u64 cost;
245
246 BUILD_BUG_ON(offsetof(struct htab_elem, htab) !=
247 offsetof(struct htab_elem, hash_node.pprev));
248 BUILD_BUG_ON(offsetof(struct htab_elem, fnode.next) !=
249 offsetof(struct htab_elem, hash_node.pprev));
250
251 if (lru && !capable(CAP_SYS_ADMIN))
252 /* LRU implementation is much complicated than other
253 * maps. Hence, limit to CAP_SYS_ADMIN for now.
254 */
255 return ERR_PTR(-EPERM);
256
257 if (attr->map_flags & ~HTAB_CREATE_FLAG_MASK)
258 /* reserved bits should not be used */
259 return ERR_PTR(-EINVAL);
260
261 if (!lru && percpu_lru)
262 return ERR_PTR(-EINVAL);
263
264 if (lru && !prealloc)
265 return ERR_PTR(-ENOTSUPP);
266
267 if (numa_node != NUMA_NO_NODE && (percpu || percpu_lru))
268 return ERR_PTR(-EINVAL);
269
270 htab = kzalloc(sizeof(*htab), GFP_USER);
271 if (!htab)
272 return ERR_PTR(-ENOMEM);
273
274 /* mandatory map attributes */
275 htab->map.map_type = attr->map_type;
276 htab->map.key_size = attr->key_size;
277 htab->map.value_size = attr->value_size;
278 htab->map.max_entries = attr->max_entries;
279 htab->map.map_flags = attr->map_flags;
280 htab->map.numa_node = numa_node;
281
282 /* check sanity of attributes.
283 * value_size == 0 may be allowed in the future to use map as a set
284 */
285 err = -EINVAL;
286 if (htab->map.max_entries == 0 || htab->map.key_size == 0 ||
287 htab->map.value_size == 0)
288 goto free_htab;
289
290 if (percpu_lru) {
291 /* ensure each CPU's lru list has >=1 elements.
292 * since we are at it, make each lru list has the same
293 * number of elements.
294 */
295 htab->map.max_entries = roundup(attr->max_entries,
296 num_possible_cpus());
297 if (htab->map.max_entries < attr->max_entries)
298 htab->map.max_entries = rounddown(attr->max_entries,
299 num_possible_cpus());
300 }
301
302 /* hash table size must be power of 2 */
303 htab->n_buckets = roundup_pow_of_two(htab->map.max_entries);
304
305 err = -E2BIG;
306 if (htab->map.key_size > MAX_BPF_STACK)
307 /* eBPF programs initialize keys on stack, so they cannot be
308 * larger than max stack size
309 */
310 goto free_htab;
311
312 if (htab->map.value_size >= KMALLOC_MAX_SIZE -
313 MAX_BPF_STACK - sizeof(struct htab_elem))
314 /* if value_size is bigger, the user space won't be able to
315 * access the elements via bpf syscall. This check also makes
316 * sure that the elem_size doesn't overflow and it's
317 * kmalloc-able later in htab_map_update_elem()
318 */
319 goto free_htab;
320
321 htab->elem_size = sizeof(struct htab_elem) +
322 round_up(htab->map.key_size, 8);
323 if (percpu)
324 htab->elem_size += sizeof(void *);
325 else
326 htab->elem_size += round_up(htab->map.value_size, 8);
327
328 /* prevent zero size kmalloc and check for u32 overflow */
329 if (htab->n_buckets == 0 ||
330 htab->n_buckets > U32_MAX / sizeof(struct bucket))
331 goto free_htab;
332
333 cost = (u64) htab->n_buckets * sizeof(struct bucket) +
334 (u64) htab->elem_size * htab->map.max_entries;
335
336 if (percpu)
337 cost += (u64) round_up(htab->map.value_size, 8) *
338 num_possible_cpus() * htab->map.max_entries;
339 else
340 cost += (u64) htab->elem_size * num_possible_cpus();
341
342 if (cost >= U32_MAX - PAGE_SIZE)
343 /* make sure page count doesn't overflow */
344 goto free_htab;
345
346 htab->map.pages = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT;
347
348 /* if map size is larger than memlock limit, reject it early */
349 err = bpf_map_precharge_memlock(htab->map.pages);
350 if (err)
351 goto free_htab;
352
353 err = -ENOMEM;
354 htab->buckets = bpf_map_area_alloc(htab->n_buckets *
355 sizeof(struct bucket),
356 htab->map.numa_node);
357 if (!htab->buckets)
358 goto free_htab;
359
360 for (i = 0; i < htab->n_buckets; i++) {
361 INIT_HLIST_NULLS_HEAD(&htab->buckets[i].head, i);
362 raw_spin_lock_init(&htab->buckets[i].lock);
363 }
364
365 if (prealloc) {
366 err = prealloc_init(htab);
367 if (err)
368 goto free_buckets;
369
370 if (!percpu && !lru) {
371 /* lru itself can remove the least used element, so
372 * there is no need for an extra elem during map_update.
373 */
374 err = alloc_extra_elems(htab);
375 if (err)
376 goto free_prealloc;
377 }
378 }
379
380 return &htab->map;
381
382 free_prealloc:
383 prealloc_destroy(htab);
384 free_buckets:
385 bpf_map_area_free(htab->buckets);
386 free_htab:
387 kfree(htab);
388 return ERR_PTR(err);
389 }
390
391 static inline u32 htab_map_hash(const void *key, u32 key_len)
392 {
393 return jhash(key, key_len, 0);
394 }
395
396 static inline struct bucket *__select_bucket(struct bpf_htab *htab, u32 hash)
397 {
398 return &htab->buckets[hash & (htab->n_buckets - 1)];
399 }
400
401 static inline struct hlist_nulls_head *select_bucket(struct bpf_htab *htab, u32 hash)
402 {
403 return &__select_bucket(htab, hash)->head;
404 }
405
406 /* this lookup function can only be called with bucket lock taken */
407 static struct htab_elem *lookup_elem_raw(struct hlist_nulls_head *head, u32 hash,
408 void *key, u32 key_size)
409 {
410 struct hlist_nulls_node *n;
411 struct htab_elem *l;
412
413 hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
414 if (l->hash == hash && !memcmp(&l->key, key, key_size))
415 return l;
416
417 return NULL;
418 }
419
420 /* can be called without bucket lock. it will repeat the loop in
421 * the unlikely event when elements moved from one bucket into another
422 * while link list is being walked
423 */
424 static struct htab_elem *lookup_nulls_elem_raw(struct hlist_nulls_head *head,
425 u32 hash, void *key,
426 u32 key_size, u32 n_buckets)
427 {
428 struct hlist_nulls_node *n;
429 struct htab_elem *l;
430
431 again:
432 hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
433 if (l->hash == hash && !memcmp(&l->key, key, key_size))
434 return l;
435
436 if (unlikely(get_nulls_value(n) != (hash & (n_buckets - 1))))
437 goto again;
438
439 return NULL;
440 }
441
442 /* Called from syscall or from eBPF program directly, so
443 * arguments have to match bpf_map_lookup_elem() exactly.
444 * The return value is adjusted by BPF instructions
445 * in htab_map_gen_lookup().
446 */
447 static void *__htab_map_lookup_elem(struct bpf_map *map, void *key)
448 {
449 struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
450 struct hlist_nulls_head *head;
451 struct htab_elem *l;
452 u32 hash, key_size;
453
454 /* Must be called with rcu_read_lock. */
455 WARN_ON_ONCE(!rcu_read_lock_held());
456
457 key_size = map->key_size;
458
459 hash = htab_map_hash(key, key_size);
460
461 head = select_bucket(htab, hash);
462
463 l = lookup_nulls_elem_raw(head, hash, key, key_size, htab->n_buckets);
464
465 return l;
466 }
467
468 static void *htab_map_lookup_elem(struct bpf_map *map, void *key)
469 {
470 struct htab_elem *l = __htab_map_lookup_elem(map, key);
471
472 if (l)
473 return l->key + round_up(map->key_size, 8);
474
475 return NULL;
476 }
477
478 /* inline bpf_map_lookup_elem() call.
479 * Instead of:
480 * bpf_prog
481 * bpf_map_lookup_elem
482 * map->ops->map_lookup_elem
483 * htab_map_lookup_elem
484 * __htab_map_lookup_elem
485 * do:
486 * bpf_prog
487 * __htab_map_lookup_elem
488 */
489 static u32 htab_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
490 {
491 struct bpf_insn *insn = insn_buf;
492 const int ret = BPF_REG_0;
493
494 *insn++ = BPF_EMIT_CALL((u64 (*)(u64, u64, u64, u64, u64))__htab_map_lookup_elem);
495 *insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 1);
496 *insn++ = BPF_ALU64_IMM(BPF_ADD, ret,
497 offsetof(struct htab_elem, key) +
498 round_up(map->key_size, 8));
499 return insn - insn_buf;
500 }
501
502 static void *htab_lru_map_lookup_elem(struct bpf_map *map, void *key)
503 {
504 struct htab_elem *l = __htab_map_lookup_elem(map, key);
505
506 if (l) {
507 bpf_lru_node_set_ref(&l->lru_node);
508 return l->key + round_up(map->key_size, 8);
509 }
510
511 return NULL;
512 }
513
514 static u32 htab_lru_map_gen_lookup(struct bpf_map *map,
515 struct bpf_insn *insn_buf)
516 {
517 struct bpf_insn *insn = insn_buf;
518 const int ret = BPF_REG_0;
519 const int ref_reg = BPF_REG_1;
520
521 *insn++ = BPF_EMIT_CALL((u64 (*)(u64, u64, u64, u64, u64))__htab_map_lookup_elem);
522 *insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 4);
523 *insn++ = BPF_LDX_MEM(BPF_B, ref_reg, ret,
524 offsetof(struct htab_elem, lru_node) +
525 offsetof(struct bpf_lru_node, ref));
526 *insn++ = BPF_JMP_IMM(BPF_JNE, ref_reg, 0, 1);
527 *insn++ = BPF_ST_MEM(BPF_B, ret,
528 offsetof(struct htab_elem, lru_node) +
529 offsetof(struct bpf_lru_node, ref),
530 1);
531 *insn++ = BPF_ALU64_IMM(BPF_ADD, ret,
532 offsetof(struct htab_elem, key) +
533 round_up(map->key_size, 8));
534 return insn - insn_buf;
535 }
536
537 /* It is called from the bpf_lru_list when the LRU needs to delete
538 * older elements from the htab.
539 */
540 static bool htab_lru_map_delete_node(void *arg, struct bpf_lru_node *node)
541 {
542 struct bpf_htab *htab = (struct bpf_htab *)arg;
543 struct htab_elem *l = NULL, *tgt_l;
544 struct hlist_nulls_head *head;
545 struct hlist_nulls_node *n;
546 unsigned long flags;
547 struct bucket *b;
548
549 tgt_l = container_of(node, struct htab_elem, lru_node);
550 b = __select_bucket(htab, tgt_l->hash);
551 head = &b->head;
552
553 raw_spin_lock_irqsave(&b->lock, flags);
554
555 hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
556 if (l == tgt_l) {
557 hlist_nulls_del_rcu(&l->hash_node);
558 break;
559 }
560
561 raw_spin_unlock_irqrestore(&b->lock, flags);
562
563 return l == tgt_l;
564 }
565
566 /* Called from syscall */
567 static int htab_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
568 {
569 struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
570 struct hlist_nulls_head *head;
571 struct htab_elem *l, *next_l;
572 u32 hash, key_size;
573 int i = 0;
574
575 WARN_ON_ONCE(!rcu_read_lock_held());
576
577 key_size = map->key_size;
578
579 if (!key)
580 goto find_first_elem;
581
582 hash = htab_map_hash(key, key_size);
583
584 head = select_bucket(htab, hash);
585
586 /* lookup the key */
587 l = lookup_nulls_elem_raw(head, hash, key, key_size, htab->n_buckets);
588
589 if (!l)
590 goto find_first_elem;
591
592 /* key was found, get next key in the same bucket */
593 next_l = hlist_nulls_entry_safe(rcu_dereference_raw(hlist_nulls_next_rcu(&l->hash_node)),
594 struct htab_elem, hash_node);
595
596 if (next_l) {
597 /* if next elem in this hash list is non-zero, just return it */
598 memcpy(next_key, next_l->key, key_size);
599 return 0;
600 }
601
602 /* no more elements in this hash list, go to the next bucket */
603 i = hash & (htab->n_buckets - 1);
604 i++;
605
606 find_first_elem:
607 /* iterate over buckets */
608 for (; i < htab->n_buckets; i++) {
609 head = select_bucket(htab, i);
610
611 /* pick first element in the bucket */
612 next_l = hlist_nulls_entry_safe(rcu_dereference_raw(hlist_nulls_first_rcu(head)),
613 struct htab_elem, hash_node);
614 if (next_l) {
615 /* if it's not empty, just return it */
616 memcpy(next_key, next_l->key, key_size);
617 return 0;
618 }
619 }
620
621 /* iterated over all buckets and all elements */
622 return -ENOENT;
623 }
624
625 static void htab_elem_free(struct bpf_htab *htab, struct htab_elem *l)
626 {
627 if (htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH)
628 free_percpu(htab_elem_get_ptr(l, htab->map.key_size));
629 kfree(l);
630 }
631
632 static void htab_elem_free_rcu(struct rcu_head *head)
633 {
634 struct htab_elem *l = container_of(head, struct htab_elem, rcu);
635 struct bpf_htab *htab = l->htab;
636
637 /* must increment bpf_prog_active to avoid kprobe+bpf triggering while
638 * we're calling kfree, otherwise deadlock is possible if kprobes
639 * are placed somewhere inside of slub
640 */
641 preempt_disable();
642 __this_cpu_inc(bpf_prog_active);
643 htab_elem_free(htab, l);
644 __this_cpu_dec(bpf_prog_active);
645 preempt_enable();
646 }
647
648 static void free_htab_elem(struct bpf_htab *htab, struct htab_elem *l)
649 {
650 struct bpf_map *map = &htab->map;
651
652 if (map->ops->map_fd_put_ptr) {
653 void *ptr = fd_htab_map_get_ptr(map, l);
654
655 map->ops->map_fd_put_ptr(ptr);
656 }
657
658 if (htab_is_prealloc(htab)) {
659 pcpu_freelist_push(&htab->freelist, &l->fnode);
660 } else {
661 atomic_dec(&htab->count);
662 l->htab = htab;
663 call_rcu(&l->rcu, htab_elem_free_rcu);
664 }
665 }
666
667 static void pcpu_copy_value(struct bpf_htab *htab, void __percpu *pptr,
668 void *value, bool onallcpus)
669 {
670 if (!onallcpus) {
671 /* copy true value_size bytes */
672 memcpy(this_cpu_ptr(pptr), value, htab->map.value_size);
673 } else {
674 u32 size = round_up(htab->map.value_size, 8);
675 int off = 0, cpu;
676
677 for_each_possible_cpu(cpu) {
678 bpf_long_memcpy(per_cpu_ptr(pptr, cpu),
679 value + off, size);
680 off += size;
681 }
682 }
683 }
684
685 static bool fd_htab_map_needs_adjust(const struct bpf_htab *htab)
686 {
687 return htab->map.map_type == BPF_MAP_TYPE_HASH_OF_MAPS &&
688 BITS_PER_LONG == 64;
689 }
690
691 static u32 htab_size_value(const struct bpf_htab *htab, bool percpu)
692 {
693 u32 size = htab->map.value_size;
694
695 if (percpu || fd_htab_map_needs_adjust(htab))
696 size = round_up(size, 8);
697 return size;
698 }
699
700 static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key,
701 void *value, u32 key_size, u32 hash,
702 bool percpu, bool onallcpus,
703 struct htab_elem *old_elem)
704 {
705 u32 size = htab_size_value(htab, percpu);
706 bool prealloc = htab_is_prealloc(htab);
707 struct htab_elem *l_new, **pl_new;
708 void __percpu *pptr;
709
710 if (prealloc) {
711 if (old_elem) {
712 /* if we're updating the existing element,
713 * use per-cpu extra elems to avoid freelist_pop/push
714 */
715 pl_new = this_cpu_ptr(htab->extra_elems);
716 l_new = *pl_new;
717 *pl_new = old_elem;
718 } else {
719 struct pcpu_freelist_node *l;
720
721 l = pcpu_freelist_pop(&htab->freelist);
722 if (!l)
723 return ERR_PTR(-E2BIG);
724 l_new = container_of(l, struct htab_elem, fnode);
725 }
726 } else {
727 if (atomic_inc_return(&htab->count) > htab->map.max_entries)
728 if (!old_elem) {
729 /* when map is full and update() is replacing
730 * old element, it's ok to allocate, since
731 * old element will be freed immediately.
732 * Otherwise return an error
733 */
734 atomic_dec(&htab->count);
735 return ERR_PTR(-E2BIG);
736 }
737 l_new = kmalloc_node(htab->elem_size, GFP_ATOMIC | __GFP_NOWARN,
738 htab->map.numa_node);
739 if (!l_new)
740 return ERR_PTR(-ENOMEM);
741 }
742
743 memcpy(l_new->key, key, key_size);
744 if (percpu) {
745 if (prealloc) {
746 pptr = htab_elem_get_ptr(l_new, key_size);
747 } else {
748 /* alloc_percpu zero-fills */
749 pptr = __alloc_percpu_gfp(size, 8,
750 GFP_ATOMIC | __GFP_NOWARN);
751 if (!pptr) {
752 kfree(l_new);
753 return ERR_PTR(-ENOMEM);
754 }
755 }
756
757 pcpu_copy_value(htab, pptr, value, onallcpus);
758
759 if (!prealloc)
760 htab_elem_set_ptr(l_new, key_size, pptr);
761 } else {
762 memcpy(l_new->key + round_up(key_size, 8), value, size);
763 }
764
765 l_new->hash = hash;
766 return l_new;
767 }
768
769 static int check_flags(struct bpf_htab *htab, struct htab_elem *l_old,
770 u64 map_flags)
771 {
772 if (l_old && map_flags == BPF_NOEXIST)
773 /* elem already exists */
774 return -EEXIST;
775
776 if (!l_old && map_flags == BPF_EXIST)
777 /* elem doesn't exist, cannot update it */
778 return -ENOENT;
779
780 return 0;
781 }
782
783 /* Called from syscall or from eBPF program */
784 static int htab_map_update_elem(struct bpf_map *map, void *key, void *value,
785 u64 map_flags)
786 {
787 struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
788 struct htab_elem *l_new = NULL, *l_old;
789 struct hlist_nulls_head *head;
790 unsigned long flags;
791 struct bucket *b;
792 u32 key_size, hash;
793 int ret;
794
795 if (unlikely(map_flags > BPF_EXIST))
796 /* unknown flags */
797 return -EINVAL;
798
799 WARN_ON_ONCE(!rcu_read_lock_held());
800
801 key_size = map->key_size;
802
803 hash = htab_map_hash(key, key_size);
804
805 b = __select_bucket(htab, hash);
806 head = &b->head;
807
808 /* bpf_map_update_elem() can be called in_irq() */
809 raw_spin_lock_irqsave(&b->lock, flags);
810
811 l_old = lookup_elem_raw(head, hash, key, key_size);
812
813 ret = check_flags(htab, l_old, map_flags);
814 if (ret)
815 goto err;
816
817 l_new = alloc_htab_elem(htab, key, value, key_size, hash, false, false,
818 l_old);
819 if (IS_ERR(l_new)) {
820 /* all pre-allocated elements are in use or memory exhausted */
821 ret = PTR_ERR(l_new);
822 goto err;
823 }
824
825 /* add new element to the head of the list, so that
826 * concurrent search will find it before old elem
827 */
828 hlist_nulls_add_head_rcu(&l_new->hash_node, head);
829 if (l_old) {
830 hlist_nulls_del_rcu(&l_old->hash_node);
831 if (!htab_is_prealloc(htab))
832 free_htab_elem(htab, l_old);
833 }
834 ret = 0;
835 err:
836 raw_spin_unlock_irqrestore(&b->lock, flags);
837 return ret;
838 }
839
840 static int htab_lru_map_update_elem(struct bpf_map *map, void *key, void *value,
841 u64 map_flags)
842 {
843 struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
844 struct htab_elem *l_new, *l_old = NULL;
845 struct hlist_nulls_head *head;
846 unsigned long flags;
847 struct bucket *b;
848 u32 key_size, hash;
849 int ret;
850
851 if (unlikely(map_flags > BPF_EXIST))
852 /* unknown flags */
853 return -EINVAL;
854
855 WARN_ON_ONCE(!rcu_read_lock_held());
856
857 key_size = map->key_size;
858
859 hash = htab_map_hash(key, key_size);
860
861 b = __select_bucket(htab, hash);
862 head = &b->head;
863
864 /* For LRU, we need to alloc before taking bucket's
865 * spinlock because getting free nodes from LRU may need
866 * to remove older elements from htab and this removal
867 * operation will need a bucket lock.
868 */
869 l_new = prealloc_lru_pop(htab, key, hash);
870 if (!l_new)
871 return -ENOMEM;
872 memcpy(l_new->key + round_up(map->key_size, 8), value, map->value_size);
873
874 /* bpf_map_update_elem() can be called in_irq() */
875 raw_spin_lock_irqsave(&b->lock, flags);
876
877 l_old = lookup_elem_raw(head, hash, key, key_size);
878
879 ret = check_flags(htab, l_old, map_flags);
880 if (ret)
881 goto err;
882
883 /* add new element to the head of the list, so that
884 * concurrent search will find it before old elem
885 */
886 hlist_nulls_add_head_rcu(&l_new->hash_node, head);
887 if (l_old) {
888 bpf_lru_node_set_ref(&l_new->lru_node);
889 hlist_nulls_del_rcu(&l_old->hash_node);
890 }
891 ret = 0;
892
893 err:
894 raw_spin_unlock_irqrestore(&b->lock, flags);
895
896 if (ret)
897 bpf_lru_push_free(&htab->lru, &l_new->lru_node);
898 else if (l_old)
899 bpf_lru_push_free(&htab->lru, &l_old->lru_node);
900
901 return ret;
902 }
903
904 static int __htab_percpu_map_update_elem(struct bpf_map *map, void *key,
905 void *value, u64 map_flags,
906 bool onallcpus)
907 {
908 struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
909 struct htab_elem *l_new = NULL, *l_old;
910 struct hlist_nulls_head *head;
911 unsigned long flags;
912 struct bucket *b;
913 u32 key_size, hash;
914 int ret;
915
916 if (unlikely(map_flags > BPF_EXIST))
917 /* unknown flags */
918 return -EINVAL;
919
920 WARN_ON_ONCE(!rcu_read_lock_held());
921
922 key_size = map->key_size;
923
924 hash = htab_map_hash(key, key_size);
925
926 b = __select_bucket(htab, hash);
927 head = &b->head;
928
929 /* bpf_map_update_elem() can be called in_irq() */
930 raw_spin_lock_irqsave(&b->lock, flags);
931
932 l_old = lookup_elem_raw(head, hash, key, key_size);
933
934 ret = check_flags(htab, l_old, map_flags);
935 if (ret)
936 goto err;
937
938 if (l_old) {
939 /* per-cpu hash map can update value in-place */
940 pcpu_copy_value(htab, htab_elem_get_ptr(l_old, key_size),
941 value, onallcpus);
942 } else {
943 l_new = alloc_htab_elem(htab, key, value, key_size,
944 hash, true, onallcpus, NULL);
945 if (IS_ERR(l_new)) {
946 ret = PTR_ERR(l_new);
947 goto err;
948 }
949 hlist_nulls_add_head_rcu(&l_new->hash_node, head);
950 }
951 ret = 0;
952 err:
953 raw_spin_unlock_irqrestore(&b->lock, flags);
954 return ret;
955 }
956
957 static int __htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
958 void *value, u64 map_flags,
959 bool onallcpus)
960 {
961 struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
962 struct htab_elem *l_new = NULL, *l_old;
963 struct hlist_nulls_head *head;
964 unsigned long flags;
965 struct bucket *b;
966 u32 key_size, hash;
967 int ret;
968
969 if (unlikely(map_flags > BPF_EXIST))
970 /* unknown flags */
971 return -EINVAL;
972
973 WARN_ON_ONCE(!rcu_read_lock_held());
974
975 key_size = map->key_size;
976
977 hash = htab_map_hash(key, key_size);
978
979 b = __select_bucket(htab, hash);
980 head = &b->head;
981
982 /* For LRU, we need to alloc before taking bucket's
983 * spinlock because LRU's elem alloc may need
984 * to remove older elem from htab and this removal
985 * operation will need a bucket lock.
986 */
987 if (map_flags != BPF_EXIST) {
988 l_new = prealloc_lru_pop(htab, key, hash);
989 if (!l_new)
990 return -ENOMEM;
991 }
992
993 /* bpf_map_update_elem() can be called in_irq() */
994 raw_spin_lock_irqsave(&b->lock, flags);
995
996 l_old = lookup_elem_raw(head, hash, key, key_size);
997
998 ret = check_flags(htab, l_old, map_flags);
999 if (ret)
1000 goto err;
1001
1002 if (l_old) {
1003 bpf_lru_node_set_ref(&l_old->lru_node);
1004
1005 /* per-cpu hash map can update value in-place */
1006 pcpu_copy_value(htab, htab_elem_get_ptr(l_old, key_size),
1007 value, onallcpus);
1008 } else {
1009 pcpu_copy_value(htab, htab_elem_get_ptr(l_new, key_size),
1010 value, onallcpus);
1011 hlist_nulls_add_head_rcu(&l_new->hash_node, head);
1012 l_new = NULL;
1013 }
1014 ret = 0;
1015 err:
1016 raw_spin_unlock_irqrestore(&b->lock, flags);
1017 if (l_new)
1018 bpf_lru_push_free(&htab->lru, &l_new->lru_node);
1019 return ret;
1020 }
1021
1022 static int htab_percpu_map_update_elem(struct bpf_map *map, void *key,
1023 void *value, u64 map_flags)
1024 {
1025 return __htab_percpu_map_update_elem(map, key, value, map_flags, false);
1026 }
1027
1028 static int htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
1029 void *value, u64 map_flags)
1030 {
1031 return __htab_lru_percpu_map_update_elem(map, key, value, map_flags,
1032 false);
1033 }
1034
1035 /* Called from syscall or from eBPF program */
1036 static int htab_map_delete_elem(struct bpf_map *map, void *key)
1037 {
1038 struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1039 struct hlist_nulls_head *head;
1040 struct bucket *b;
1041 struct htab_elem *l;
1042 unsigned long flags;
1043 u32 hash, key_size;
1044 int ret = -ENOENT;
1045
1046 WARN_ON_ONCE(!rcu_read_lock_held());
1047
1048 key_size = map->key_size;
1049
1050 hash = htab_map_hash(key, key_size);
1051 b = __select_bucket(htab, hash);
1052 head = &b->head;
1053
1054 raw_spin_lock_irqsave(&b->lock, flags);
1055
1056 l = lookup_elem_raw(head, hash, key, key_size);
1057
1058 if (l) {
1059 hlist_nulls_del_rcu(&l->hash_node);
1060 free_htab_elem(htab, l);
1061 ret = 0;
1062 }
1063
1064 raw_spin_unlock_irqrestore(&b->lock, flags);
1065 return ret;
1066 }
1067
1068 static int htab_lru_map_delete_elem(struct bpf_map *map, void *key)
1069 {
1070 struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1071 struct hlist_nulls_head *head;
1072 struct bucket *b;
1073 struct htab_elem *l;
1074 unsigned long flags;
1075 u32 hash, key_size;
1076 int ret = -ENOENT;
1077
1078 WARN_ON_ONCE(!rcu_read_lock_held());
1079
1080 key_size = map->key_size;
1081
1082 hash = htab_map_hash(key, key_size);
1083 b = __select_bucket(htab, hash);
1084 head = &b->head;
1085
1086 raw_spin_lock_irqsave(&b->lock, flags);
1087
1088 l = lookup_elem_raw(head, hash, key, key_size);
1089
1090 if (l) {
1091 hlist_nulls_del_rcu(&l->hash_node);
1092 ret = 0;
1093 }
1094
1095 raw_spin_unlock_irqrestore(&b->lock, flags);
1096 if (l)
1097 bpf_lru_push_free(&htab->lru, &l->lru_node);
1098 return ret;
1099 }
1100
1101 static void delete_all_elements(struct bpf_htab *htab)
1102 {
1103 int i;
1104
1105 for (i = 0; i < htab->n_buckets; i++) {
1106 struct hlist_nulls_head *head = select_bucket(htab, i);
1107 struct hlist_nulls_node *n;
1108 struct htab_elem *l;
1109
1110 hlist_nulls_for_each_entry_safe(l, n, head, hash_node) {
1111 hlist_nulls_del_rcu(&l->hash_node);
1112 htab_elem_free(htab, l);
1113 }
1114 }
1115 }
1116
1117 /* Called when map->refcnt goes to zero, either from workqueue or from syscall */
1118 static void htab_map_free(struct bpf_map *map)
1119 {
1120 struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1121
1122 /* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
1123 * so the programs (can be more than one that used this map) were
1124 * disconnected from events. Wait for outstanding critical sections in
1125 * these programs to complete
1126 */
1127 synchronize_rcu();
1128
1129 /* some of free_htab_elem() callbacks for elements of this map may
1130 * not have executed. Wait for them.
1131 */
1132 rcu_barrier();
1133 if (!htab_is_prealloc(htab))
1134 delete_all_elements(htab);
1135 else
1136 prealloc_destroy(htab);
1137
1138 free_percpu(htab->extra_elems);
1139 bpf_map_area_free(htab->buckets);
1140 kfree(htab);
1141 }
1142
1143 const struct bpf_map_ops htab_map_ops = {
1144 .map_alloc = htab_map_alloc,
1145 .map_free = htab_map_free,
1146 .map_get_next_key = htab_map_get_next_key,
1147 .map_lookup_elem = htab_map_lookup_elem,
1148 .map_update_elem = htab_map_update_elem,
1149 .map_delete_elem = htab_map_delete_elem,
1150 .map_gen_lookup = htab_map_gen_lookup,
1151 };
1152
1153 const struct bpf_map_ops htab_lru_map_ops = {
1154 .map_alloc = htab_map_alloc,
1155 .map_free = htab_map_free,
1156 .map_get_next_key = htab_map_get_next_key,
1157 .map_lookup_elem = htab_lru_map_lookup_elem,
1158 .map_update_elem = htab_lru_map_update_elem,
1159 .map_delete_elem = htab_lru_map_delete_elem,
1160 .map_gen_lookup = htab_lru_map_gen_lookup,
1161 };
1162
1163 /* Called from eBPF program */
1164 static void *htab_percpu_map_lookup_elem(struct bpf_map *map, void *key)
1165 {
1166 struct htab_elem *l = __htab_map_lookup_elem(map, key);
1167
1168 if (l)
1169 return this_cpu_ptr(htab_elem_get_ptr(l, map->key_size));
1170 else
1171 return NULL;
1172 }
1173
1174 static void *htab_lru_percpu_map_lookup_elem(struct bpf_map *map, void *key)
1175 {
1176 struct htab_elem *l = __htab_map_lookup_elem(map, key);
1177
1178 if (l) {
1179 bpf_lru_node_set_ref(&l->lru_node);
1180 return this_cpu_ptr(htab_elem_get_ptr(l, map->key_size));
1181 }
1182
1183 return NULL;
1184 }
1185
1186 int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value)
1187 {
1188 struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1189 struct htab_elem *l;
1190 void __percpu *pptr;
1191 int ret = -ENOENT;
1192 int cpu, off = 0;
1193 u32 size;
1194
1195 /* per_cpu areas are zero-filled and bpf programs can only
1196 * access 'value_size' of them, so copying rounded areas
1197 * will not leak any kernel data
1198 */
1199 size = round_up(map->value_size, 8);
1200 rcu_read_lock();
1201 l = __htab_map_lookup_elem(map, key);
1202 if (!l)
1203 goto out;
1204 if (htab_is_lru(htab))
1205 bpf_lru_node_set_ref(&l->lru_node);
1206 pptr = htab_elem_get_ptr(l, map->key_size);
1207 for_each_possible_cpu(cpu) {
1208 bpf_long_memcpy(value + off,
1209 per_cpu_ptr(pptr, cpu), size);
1210 off += size;
1211 }
1212 ret = 0;
1213 out:
1214 rcu_read_unlock();
1215 return ret;
1216 }
1217
1218 int bpf_percpu_hash_update(struct bpf_map *map, void *key, void *value,
1219 u64 map_flags)
1220 {
1221 struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1222 int ret;
1223
1224 rcu_read_lock();
1225 if (htab_is_lru(htab))
1226 ret = __htab_lru_percpu_map_update_elem(map, key, value,
1227 map_flags, true);
1228 else
1229 ret = __htab_percpu_map_update_elem(map, key, value, map_flags,
1230 true);
1231 rcu_read_unlock();
1232
1233 return ret;
1234 }
1235
1236 const struct bpf_map_ops htab_percpu_map_ops = {
1237 .map_alloc = htab_map_alloc,
1238 .map_free = htab_map_free,
1239 .map_get_next_key = htab_map_get_next_key,
1240 .map_lookup_elem = htab_percpu_map_lookup_elem,
1241 .map_update_elem = htab_percpu_map_update_elem,
1242 .map_delete_elem = htab_map_delete_elem,
1243 };
1244
1245 const struct bpf_map_ops htab_lru_percpu_map_ops = {
1246 .map_alloc = htab_map_alloc,
1247 .map_free = htab_map_free,
1248 .map_get_next_key = htab_map_get_next_key,
1249 .map_lookup_elem = htab_lru_percpu_map_lookup_elem,
1250 .map_update_elem = htab_lru_percpu_map_update_elem,
1251 .map_delete_elem = htab_lru_map_delete_elem,
1252 };
1253
1254 static struct bpf_map *fd_htab_map_alloc(union bpf_attr *attr)
1255 {
1256 if (attr->value_size != sizeof(u32))
1257 return ERR_PTR(-EINVAL);
1258 return htab_map_alloc(attr);
1259 }
1260
1261 static void fd_htab_map_free(struct bpf_map *map)
1262 {
1263 struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1264 struct hlist_nulls_node *n;
1265 struct hlist_nulls_head *head;
1266 struct htab_elem *l;
1267 int i;
1268
1269 for (i = 0; i < htab->n_buckets; i++) {
1270 head = select_bucket(htab, i);
1271
1272 hlist_nulls_for_each_entry_safe(l, n, head, hash_node) {
1273 void *ptr = fd_htab_map_get_ptr(map, l);
1274
1275 map->ops->map_fd_put_ptr(ptr);
1276 }
1277 }
1278
1279 htab_map_free(map);
1280 }
1281
1282 /* only called from syscall */
1283 int bpf_fd_htab_map_lookup_elem(struct bpf_map *map, void *key, u32 *value)
1284 {
1285 void **ptr;
1286 int ret = 0;
1287
1288 if (!map->ops->map_fd_sys_lookup_elem)
1289 return -ENOTSUPP;
1290
1291 rcu_read_lock();
1292 ptr = htab_map_lookup_elem(map, key);
1293 if (ptr)
1294 *value = map->ops->map_fd_sys_lookup_elem(READ_ONCE(*ptr));
1295 else
1296 ret = -ENOENT;
1297 rcu_read_unlock();
1298
1299 return ret;
1300 }
1301
1302 /* only called from syscall */
1303 int bpf_fd_htab_map_update_elem(struct bpf_map *map, struct file *map_file,
1304 void *key, void *value, u64 map_flags)
1305 {
1306 void *ptr;
1307 int ret;
1308 u32 ufd = *(u32 *)value;
1309
1310 ptr = map->ops->map_fd_get_ptr(map, map_file, ufd);
1311 if (IS_ERR(ptr))
1312 return PTR_ERR(ptr);
1313
1314 ret = htab_map_update_elem(map, key, &ptr, map_flags);
1315 if (ret)
1316 map->ops->map_fd_put_ptr(ptr);
1317
1318 return ret;
1319 }
1320
1321 static struct bpf_map *htab_of_map_alloc(union bpf_attr *attr)
1322 {
1323 struct bpf_map *map, *inner_map_meta;
1324
1325 inner_map_meta = bpf_map_meta_alloc(attr->inner_map_fd);
1326 if (IS_ERR(inner_map_meta))
1327 return inner_map_meta;
1328
1329 map = fd_htab_map_alloc(attr);
1330 if (IS_ERR(map)) {
1331 bpf_map_meta_free(inner_map_meta);
1332 return map;
1333 }
1334
1335 map->inner_map_meta = inner_map_meta;
1336
1337 return map;
1338 }
1339
1340 static void *htab_of_map_lookup_elem(struct bpf_map *map, void *key)
1341 {
1342 struct bpf_map **inner_map = htab_map_lookup_elem(map, key);
1343
1344 if (!inner_map)
1345 return NULL;
1346
1347 return READ_ONCE(*inner_map);
1348 }
1349
1350 static u32 htab_of_map_gen_lookup(struct bpf_map *map,
1351 struct bpf_insn *insn_buf)
1352 {
1353 struct bpf_insn *insn = insn_buf;
1354 const int ret = BPF_REG_0;
1355
1356 *insn++ = BPF_EMIT_CALL((u64 (*)(u64, u64, u64, u64, u64))__htab_map_lookup_elem);
1357 *insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 2);
1358 *insn++ = BPF_ALU64_IMM(BPF_ADD, ret,
1359 offsetof(struct htab_elem, key) +
1360 round_up(map->key_size, 8));
1361 *insn++ = BPF_LDX_MEM(BPF_DW, ret, ret, 0);
1362
1363 return insn - insn_buf;
1364 }
1365
1366 static void htab_of_map_free(struct bpf_map *map)
1367 {
1368 bpf_map_meta_free(map->inner_map_meta);
1369 fd_htab_map_free(map);
1370 }
1371
1372 const struct bpf_map_ops htab_of_maps_map_ops = {
1373 .map_alloc = htab_of_map_alloc,
1374 .map_free = htab_of_map_free,
1375 .map_get_next_key = htab_map_get_next_key,
1376 .map_lookup_elem = htab_of_map_lookup_elem,
1377 .map_delete_elem = htab_map_delete_elem,
1378 .map_fd_get_ptr = bpf_map_fd_get_ptr,
1379 .map_fd_put_ptr = bpf_map_fd_put_ptr,
1380 .map_fd_sys_lookup_elem = bpf_map_fd_sys_lookup_elem,
1381 .map_gen_lookup = htab_of_map_gen_lookup,
1382 };
CRIS linux kernel tree