Commit | Line | Data |
---|---|---|
450af8d0 KS |
1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* Copyright (c) 2019 Facebook */ | |
3 | #include <linux/rculist.h> | |
4 | #include <linux/list.h> | |
5 | #include <linux/hash.h> | |
6 | #include <linux/types.h> | |
7 | #include <linux/spinlock.h> | |
8 | #include <linux/bpf.h> | |
9 | #include <linux/btf_ids.h> | |
10 | #include <linux/bpf_local_storage.h> | |
11 | #include <net/sock.h> | |
12 | #include <uapi/linux/sock_diag.h> | |
13 | #include <uapi/linux/btf.h> | |
0fe4b381 KS |
14 | #include <linux/rcupdate.h> |
15 | #include <linux/rcupdate_trace.h> | |
16 | #include <linux/rcupdate_wait.h> | |
450af8d0 KS |
17 | |
18 | #define BPF_LOCAL_STORAGE_CREATE_FLAG_MASK (BPF_F_NO_PREALLOC | BPF_F_CLONE) | |
19 | ||
20 | static struct bpf_local_storage_map_bucket * | |
21 | select_bucket(struct bpf_local_storage_map *smap, | |
22 | struct bpf_local_storage_elem *selem) | |
23 | { | |
24 | return &smap->buckets[hash_ptr(selem, smap->bucket_log)]; | |
25 | } | |
26 | ||
27 | static int mem_charge(struct bpf_local_storage_map *smap, void *owner, u32 size) | |
28 | { | |
29 | struct bpf_map *map = &smap->map; | |
30 | ||
31 | if (!map->ops->map_local_storage_charge) | |
32 | return 0; | |
33 | ||
34 | return map->ops->map_local_storage_charge(smap, owner, size); | |
35 | } | |
36 | ||
37 | static void mem_uncharge(struct bpf_local_storage_map *smap, void *owner, | |
38 | u32 size) | |
39 | { | |
40 | struct bpf_map *map = &smap->map; | |
41 | ||
42 | if (map->ops->map_local_storage_uncharge) | |
43 | map->ops->map_local_storage_uncharge(smap, owner, size); | |
44 | } | |
45 | ||
46 | static struct bpf_local_storage __rcu ** | |
47 | owner_storage(struct bpf_local_storage_map *smap, void *owner) | |
48 | { | |
49 | struct bpf_map *map = &smap->map; | |
50 | ||
51 | return map->ops->map_owner_storage_ptr(owner); | |
52 | } | |
53 | ||
0a09a2f9 KKD |
54 | static bool selem_linked_to_storage_lockless(const struct bpf_local_storage_elem *selem) |
55 | { | |
56 | return !hlist_unhashed_lockless(&selem->snode); | |
57 | } | |
58 | ||
450af8d0 KS |
59 | static bool selem_linked_to_storage(const struct bpf_local_storage_elem *selem) |
60 | { | |
61 | return !hlist_unhashed(&selem->snode); | |
62 | } | |
63 | ||
0a09a2f9 KKD |
64 | static bool selem_linked_to_map_lockless(const struct bpf_local_storage_elem *selem) |
65 | { | |
66 | return !hlist_unhashed_lockless(&selem->map_node); | |
67 | } | |
68 | ||
450af8d0 KS |
69 | static bool selem_linked_to_map(const struct bpf_local_storage_elem *selem) |
70 | { | |
71 | return !hlist_unhashed(&selem->map_node); | |
72 | } | |
73 | ||
74 | struct bpf_local_storage_elem * | |
75 | bpf_selem_alloc(struct bpf_local_storage_map *smap, void *owner, | |
b00fa38a | 76 | void *value, bool charge_mem, gfp_t gfp_flags) |
450af8d0 KS |
77 | { |
78 | struct bpf_local_storage_elem *selem; | |
79 | ||
80 | if (charge_mem && mem_charge(smap, owner, smap->elem_size)) | |
81 | return NULL; | |
82 | ||
08a7ce38 MKL |
83 | if (smap->bpf_ma) { |
84 | migrate_disable(); | |
85 | selem = bpf_mem_cache_alloc_flags(&smap->selem_ma, gfp_flags); | |
86 | migrate_enable(); | |
87 | if (selem) | |
88 | /* Keep the original bpf_map_kzalloc behavior | |
89 | * before started using the bpf_mem_cache_alloc. | |
90 | * | |
91 | * No need to use zero_map_value. The bpf_selem_free() | |
92 | * only does bpf_mem_cache_free when there is | |
93 | * no other bpf prog is using the selem. | |
94 | */ | |
95 | memset(SDATA(selem)->data, 0, smap->map.value_size); | |
96 | } else { | |
97 | selem = bpf_map_kzalloc(&smap->map, smap->elem_size, | |
98 | gfp_flags | __GFP_NOWARN); | |
99 | } | |
100 | ||
450af8d0 KS |
101 | if (selem) { |
102 | if (value) | |
836e49e1 | 103 | copy_map_value(&smap->map, SDATA(selem)->data, value); |
9db44fdd | 104 | /* No need to call check_and_init_map_value as memory is zero init */ |
450af8d0 KS |
105 | return selem; |
106 | } | |
107 | ||
108 | if (charge_mem) | |
109 | mem_uncharge(smap, owner, smap->elem_size); | |
110 | ||
111 | return NULL; | |
112 | } | |
113 | ||
6ae9d5e9 MKL |
114 | /* rcu tasks trace callback for bpf_ma == false */ |
115 | static void __bpf_local_storage_free_trace_rcu(struct rcu_head *rcu) | |
116 | { | |
117 | struct bpf_local_storage *local_storage; | |
118 | ||
119 | /* If RCU Tasks Trace grace period implies RCU grace period, do | |
120 | * kfree(), else do kfree_rcu(). | |
121 | */ | |
122 | local_storage = container_of(rcu, struct bpf_local_storage, rcu); | |
123 | if (rcu_trace_implies_rcu_gp()) | |
124 | kfree(local_storage); | |
125 | else | |
126 | kfree_rcu(local_storage, rcu); | |
127 | } | |
128 | ||
4cbd23cc | 129 | static void bpf_local_storage_free_rcu(struct rcu_head *rcu) |
0fe4b381 KS |
130 | { |
131 | struct bpf_local_storage *local_storage; | |
132 | ||
1288aaa2 | 133 | local_storage = container_of(rcu, struct bpf_local_storage, rcu); |
6ae9d5e9 | 134 | bpf_mem_cache_raw_free(local_storage); |
1288aaa2 MKL |
135 | } |
136 | ||
137 | static void bpf_local_storage_free_trace_rcu(struct rcu_head *rcu) | |
138 | { | |
d39d1445 | 139 | if (rcu_trace_implies_rcu_gp()) |
1288aaa2 | 140 | bpf_local_storage_free_rcu(rcu); |
d39d1445 | 141 | else |
1288aaa2 | 142 | call_rcu(rcu, bpf_local_storage_free_rcu); |
0fe4b381 KS |
143 | } |
144 | ||
6ae9d5e9 MKL |
145 | /* Handle bpf_ma == false */ |
146 | static void __bpf_local_storage_free(struct bpf_local_storage *local_storage, | |
147 | bool vanilla_rcu) | |
148 | { | |
149 | if (vanilla_rcu) | |
150 | kfree_rcu(local_storage, rcu); | |
151 | else | |
152 | call_rcu_tasks_trace(&local_storage->rcu, | |
153 | __bpf_local_storage_free_trace_rcu); | |
154 | } | |
155 | ||
7e30a847 | 156 | static void bpf_local_storage_free(struct bpf_local_storage *local_storage, |
6ae9d5e9 MKL |
157 | struct bpf_local_storage_map *smap, |
158 | bool bpf_ma, bool reuse_now) | |
7e30a847 | 159 | { |
10fd5f70 AS |
160 | if (!local_storage) |
161 | return; | |
162 | ||
6ae9d5e9 MKL |
163 | if (!bpf_ma) { |
164 | __bpf_local_storage_free(local_storage, reuse_now); | |
165 | return; | |
166 | } | |
167 | ||
168 | if (!reuse_now) { | |
7e30a847 MKL |
169 | call_rcu_tasks_trace(&local_storage->rcu, |
170 | bpf_local_storage_free_trace_rcu); | |
6ae9d5e9 MKL |
171 | return; |
172 | } | |
173 | ||
174 | if (smap) { | |
175 | migrate_disable(); | |
176 | bpf_mem_cache_free(&smap->storage_ma, local_storage); | |
177 | migrate_enable(); | |
178 | } else { | |
179 | /* smap could be NULL if the selem that triggered | |
180 | * this 'local_storage' creation had been long gone. | |
181 | * In this case, directly do call_rcu(). | |
182 | */ | |
7e30a847 | 183 | call_rcu(&local_storage->rcu, bpf_local_storage_free_rcu); |
6ae9d5e9 | 184 | } |
7e30a847 MKL |
185 | } |
186 | ||
08a7ce38 MKL |
187 | /* rcu tasks trace callback for bpf_ma == false */ |
188 | static void __bpf_selem_free_trace_rcu(struct rcu_head *rcu) | |
189 | { | |
190 | struct bpf_local_storage_elem *selem; | |
191 | ||
192 | selem = container_of(rcu, struct bpf_local_storage_elem, rcu); | |
193 | if (rcu_trace_implies_rcu_gp()) | |
194 | kfree(selem); | |
195 | else | |
196 | kfree_rcu(selem, rcu); | |
197 | } | |
198 | ||
199 | /* Handle bpf_ma == false */ | |
200 | static void __bpf_selem_free(struct bpf_local_storage_elem *selem, | |
201 | bool vanilla_rcu) | |
202 | { | |
203 | if (vanilla_rcu) | |
204 | kfree_rcu(selem, rcu); | |
205 | else | |
206 | call_rcu_tasks_trace(&selem->rcu, __bpf_selem_free_trace_rcu); | |
207 | } | |
208 | ||
f8ccf30c | 209 | static void bpf_selem_free_rcu(struct rcu_head *rcu) |
e768e3c5 KKD |
210 | { |
211 | struct bpf_local_storage_elem *selem; | |
212 | ||
213 | selem = container_of(rcu, struct bpf_local_storage_elem, rcu); | |
08a7ce38 | 214 | bpf_mem_cache_raw_free(selem); |
f8ccf30c MKL |
215 | } |
216 | ||
217 | static void bpf_selem_free_trace_rcu(struct rcu_head *rcu) | |
218 | { | |
e768e3c5 | 219 | if (rcu_trace_implies_rcu_gp()) |
f8ccf30c | 220 | bpf_selem_free_rcu(rcu); |
d39d1445 | 221 | else |
f8ccf30c | 222 | call_rcu(rcu, bpf_selem_free_rcu); |
0fe4b381 KS |
223 | } |
224 | ||
c0d63f30 MKL |
225 | void bpf_selem_free(struct bpf_local_storage_elem *selem, |
226 | struct bpf_local_storage_map *smap, | |
227 | bool reuse_now) | |
228 | { | |
229 | bpf_obj_free_fields(smap->map.record, SDATA(selem)->data); | |
08a7ce38 MKL |
230 | |
231 | if (!smap->bpf_ma) { | |
232 | __bpf_selem_free(selem, reuse_now); | |
233 | return; | |
234 | } | |
235 | ||
236 | if (!reuse_now) { | |
c0d63f30 | 237 | call_rcu_tasks_trace(&selem->rcu, bpf_selem_free_trace_rcu); |
08a7ce38 MKL |
238 | } else { |
239 | /* Instead of using the vanilla call_rcu(), | |
240 | * bpf_mem_cache_free will be able to reuse selem | |
241 | * immediately. | |
242 | */ | |
243 | migrate_disable(); | |
244 | bpf_mem_cache_free(&smap->selem_ma, selem); | |
245 | migrate_enable(); | |
246 | } | |
c0d63f30 MKL |
247 | } |
248 | ||
450af8d0 KS |
249 | /* local_storage->lock must be held and selem->local_storage == local_storage. |
250 | * The caller must ensure selem->smap is still valid to be | |
251 | * dereferenced for its smap->elem_size and smap->cache_idx. | |
252 | */ | |
c83597fa YS |
253 | static bool bpf_selem_unlink_storage_nolock(struct bpf_local_storage *local_storage, |
254 | struct bpf_local_storage_elem *selem, | |
a47eabf2 | 255 | bool uncharge_mem, bool reuse_now) |
450af8d0 KS |
256 | { |
257 | struct bpf_local_storage_map *smap; | |
258 | bool free_local_storage; | |
259 | void *owner; | |
260 | ||
0fe4b381 | 261 | smap = rcu_dereference_check(SDATA(selem)->smap, bpf_rcu_lock_held()); |
450af8d0 KS |
262 | owner = local_storage->owner; |
263 | ||
264 | /* All uncharging on the owner must be done first. | |
265 | * The owner may be freed once the last selem is unlinked | |
266 | * from local_storage. | |
267 | */ | |
268 | if (uncharge_mem) | |
269 | mem_uncharge(smap, owner, smap->elem_size); | |
270 | ||
271 | free_local_storage = hlist_is_singular_node(&selem->snode, | |
272 | &local_storage->list); | |
273 | if (free_local_storage) { | |
274 | mem_uncharge(smap, owner, sizeof(struct bpf_local_storage)); | |
275 | local_storage->owner = NULL; | |
276 | ||
277 | /* After this RCU_INIT, owner may be freed and cannot be used */ | |
278 | RCU_INIT_POINTER(*owner_storage(smap, owner), NULL); | |
279 | ||
280 | /* local_storage is not freed now. local_storage->lock is | |
281 | * still held and raw_spin_unlock_bh(&local_storage->lock) | |
282 | * will be done by the caller. | |
283 | * | |
284 | * Although the unlock will be done under | |
c561d110 | 285 | * rcu_read_lock(), it is more intuitive to |
0fe4b381 | 286 | * read if the freeing of the storage is done |
450af8d0 KS |
287 | * after the raw_spin_unlock_bh(&local_storage->lock). |
288 | * | |
289 | * Hence, a "bool free_local_storage" is returned | |
0fe4b381 KS |
290 | * to the caller which then calls then frees the storage after |
291 | * all the RCU grace periods have expired. | |
450af8d0 KS |
292 | */ |
293 | } | |
294 | hlist_del_init_rcu(&selem->snode); | |
295 | if (rcu_access_pointer(local_storage->cache[smap->cache_idx]) == | |
296 | SDATA(selem)) | |
297 | RCU_INIT_POINTER(local_storage->cache[smap->cache_idx], NULL); | |
298 | ||
c0d63f30 | 299 | bpf_selem_free(selem, smap, reuse_now); |
dcf456c9 | 300 | |
fc6652aa MKL |
301 | if (rcu_access_pointer(local_storage->smap) == smap) |
302 | RCU_INIT_POINTER(local_storage->smap, NULL); | |
303 | ||
450af8d0 KS |
304 | return free_local_storage; |
305 | } | |
306 | ||
6ae9d5e9 MKL |
307 | static bool check_storage_bpf_ma(struct bpf_local_storage *local_storage, |
308 | struct bpf_local_storage_map *storage_smap, | |
309 | struct bpf_local_storage_elem *selem) | |
310 | { | |
311 | ||
312 | struct bpf_local_storage_map *selem_smap; | |
313 | ||
314 | /* local_storage->smap may be NULL. If it is, get the bpf_ma | |
315 | * from any selem in the local_storage->list. The bpf_ma of all | |
316 | * local_storage and selem should have the same value | |
317 | * for the same map type. | |
318 | * | |
319 | * If the local_storage->list is already empty, the caller will not | |
320 | * care about the bpf_ma value also because the caller is not | |
321 | * responsibile to free the local_storage. | |
322 | */ | |
323 | ||
324 | if (storage_smap) | |
325 | return storage_smap->bpf_ma; | |
326 | ||
327 | if (!selem) { | |
328 | struct hlist_node *n; | |
329 | ||
330 | n = rcu_dereference_check(hlist_first_rcu(&local_storage->list), | |
331 | bpf_rcu_lock_held()); | |
332 | if (!n) | |
333 | return false; | |
334 | ||
335 | selem = hlist_entry(n, struct bpf_local_storage_elem, snode); | |
336 | } | |
337 | selem_smap = rcu_dereference_check(SDATA(selem)->smap, bpf_rcu_lock_held()); | |
338 | ||
339 | return selem_smap->bpf_ma; | |
340 | } | |
341 | ||
121f31f3 | 342 | static void bpf_selem_unlink_storage(struct bpf_local_storage_elem *selem, |
a47eabf2 | 343 | bool reuse_now) |
450af8d0 | 344 | { |
6ae9d5e9 | 345 | struct bpf_local_storage_map *storage_smap; |
450af8d0 | 346 | struct bpf_local_storage *local_storage; |
6ae9d5e9 | 347 | bool bpf_ma, free_local_storage = false; |
a10787e6 | 348 | unsigned long flags; |
450af8d0 | 349 | |
0a09a2f9 | 350 | if (unlikely(!selem_linked_to_storage_lockless(selem))) |
450af8d0 KS |
351 | /* selem has already been unlinked from sk */ |
352 | return; | |
353 | ||
0fe4b381 KS |
354 | local_storage = rcu_dereference_check(selem->local_storage, |
355 | bpf_rcu_lock_held()); | |
6ae9d5e9 MKL |
356 | storage_smap = rcu_dereference_check(local_storage->smap, |
357 | bpf_rcu_lock_held()); | |
358 | bpf_ma = check_storage_bpf_ma(local_storage, storage_smap, selem); | |
359 | ||
a10787e6 | 360 | raw_spin_lock_irqsave(&local_storage->lock, flags); |
450af8d0 KS |
361 | if (likely(selem_linked_to_storage(selem))) |
362 | free_local_storage = bpf_selem_unlink_storage_nolock( | |
a47eabf2 | 363 | local_storage, selem, true, reuse_now); |
a10787e6 | 364 | raw_spin_unlock_irqrestore(&local_storage->lock, flags); |
450af8d0 | 365 | |
7e30a847 | 366 | if (free_local_storage) |
6ae9d5e9 | 367 | bpf_local_storage_free(local_storage, storage_smap, bpf_ma, reuse_now); |
450af8d0 KS |
368 | } |
369 | ||
370 | void bpf_selem_link_storage_nolock(struct bpf_local_storage *local_storage, | |
371 | struct bpf_local_storage_elem *selem) | |
372 | { | |
373 | RCU_INIT_POINTER(selem->local_storage, local_storage); | |
70b97111 | 374 | hlist_add_head_rcu(&selem->snode, &local_storage->list); |
450af8d0 KS |
375 | } |
376 | ||
4cbd23cc | 377 | static void bpf_selem_unlink_map(struct bpf_local_storage_elem *selem) |
450af8d0 KS |
378 | { |
379 | struct bpf_local_storage_map *smap; | |
380 | struct bpf_local_storage_map_bucket *b; | |
a10787e6 | 381 | unsigned long flags; |
450af8d0 | 382 | |
0a09a2f9 | 383 | if (unlikely(!selem_linked_to_map_lockless(selem))) |
450af8d0 KS |
384 | /* selem has already be unlinked from smap */ |
385 | return; | |
386 | ||
0fe4b381 | 387 | smap = rcu_dereference_check(SDATA(selem)->smap, bpf_rcu_lock_held()); |
450af8d0 | 388 | b = select_bucket(smap, selem); |
a10787e6 | 389 | raw_spin_lock_irqsave(&b->lock, flags); |
450af8d0 KS |
390 | if (likely(selem_linked_to_map(selem))) |
391 | hlist_del_init_rcu(&selem->map_node); | |
a10787e6 | 392 | raw_spin_unlock_irqrestore(&b->lock, flags); |
450af8d0 KS |
393 | } |
394 | ||
395 | void bpf_selem_link_map(struct bpf_local_storage_map *smap, | |
396 | struct bpf_local_storage_elem *selem) | |
397 | { | |
398 | struct bpf_local_storage_map_bucket *b = select_bucket(smap, selem); | |
a10787e6 | 399 | unsigned long flags; |
450af8d0 | 400 | |
a10787e6 | 401 | raw_spin_lock_irqsave(&b->lock, flags); |
450af8d0 KS |
402 | RCU_INIT_POINTER(SDATA(selem)->smap, smap); |
403 | hlist_add_head_rcu(&selem->map_node, &b->list); | |
a10787e6 | 404 | raw_spin_unlock_irqrestore(&b->lock, flags); |
450af8d0 KS |
405 | } |
406 | ||
a47eabf2 | 407 | void bpf_selem_unlink(struct bpf_local_storage_elem *selem, bool reuse_now) |
450af8d0 KS |
408 | { |
409 | /* Always unlink from map before unlinking from local_storage | |
410 | * because selem will be freed after successfully unlinked from | |
411 | * the local_storage. | |
412 | */ | |
413 | bpf_selem_unlink_map(selem); | |
a47eabf2 | 414 | bpf_selem_unlink_storage(selem, reuse_now); |
450af8d0 KS |
415 | } |
416 | ||
e8b02296 | 417 | /* If cacheit_lockit is false, this lookup function is lockless */ |
450af8d0 KS |
418 | struct bpf_local_storage_data * |
419 | bpf_local_storage_lookup(struct bpf_local_storage *local_storage, | |
420 | struct bpf_local_storage_map *smap, | |
421 | bool cacheit_lockit) | |
422 | { | |
423 | struct bpf_local_storage_data *sdata; | |
424 | struct bpf_local_storage_elem *selem; | |
425 | ||
426 | /* Fast path (cache hit) */ | |
0fe4b381 KS |
427 | sdata = rcu_dereference_check(local_storage->cache[smap->cache_idx], |
428 | bpf_rcu_lock_held()); | |
450af8d0 KS |
429 | if (sdata && rcu_access_pointer(sdata->smap) == smap) |
430 | return sdata; | |
431 | ||
432 | /* Slow path (cache miss) */ | |
0fe4b381 KS |
433 | hlist_for_each_entry_rcu(selem, &local_storage->list, snode, |
434 | rcu_read_lock_trace_held()) | |
450af8d0 KS |
435 | if (rcu_access_pointer(SDATA(selem)->smap) == smap) |
436 | break; | |
437 | ||
438 | if (!selem) | |
439 | return NULL; | |
440 | ||
441 | sdata = SDATA(selem); | |
442 | if (cacheit_lockit) { | |
a10787e6 SL |
443 | unsigned long flags; |
444 | ||
450af8d0 KS |
445 | /* spinlock is needed to avoid racing with the |
446 | * parallel delete. Otherwise, publishing an already | |
447 | * deleted sdata to the cache will become a use-after-free | |
448 | * problem in the next bpf_local_storage_lookup(). | |
449 | */ | |
a10787e6 | 450 | raw_spin_lock_irqsave(&local_storage->lock, flags); |
450af8d0 KS |
451 | if (selem_linked_to_storage(selem)) |
452 | rcu_assign_pointer(local_storage->cache[smap->cache_idx], | |
453 | sdata); | |
a10787e6 | 454 | raw_spin_unlock_irqrestore(&local_storage->lock, flags); |
450af8d0 KS |
455 | } |
456 | ||
457 | return sdata; | |
458 | } | |
459 | ||
460 | static int check_flags(const struct bpf_local_storage_data *old_sdata, | |
461 | u64 map_flags) | |
462 | { | |
463 | if (old_sdata && (map_flags & ~BPF_F_LOCK) == BPF_NOEXIST) | |
464 | /* elem already exists */ | |
465 | return -EEXIST; | |
466 | ||
467 | if (!old_sdata && (map_flags & ~BPF_F_LOCK) == BPF_EXIST) | |
468 | /* elem doesn't exist, cannot update it */ | |
469 | return -ENOENT; | |
470 | ||
471 | return 0; | |
472 | } | |
473 | ||
474 | int bpf_local_storage_alloc(void *owner, | |
475 | struct bpf_local_storage_map *smap, | |
b00fa38a JK |
476 | struct bpf_local_storage_elem *first_selem, |
477 | gfp_t gfp_flags) | |
450af8d0 KS |
478 | { |
479 | struct bpf_local_storage *prev_storage, *storage; | |
480 | struct bpf_local_storage **owner_storage_ptr; | |
481 | int err; | |
482 | ||
483 | err = mem_charge(smap, owner, sizeof(*storage)); | |
484 | if (err) | |
485 | return err; | |
486 | ||
6ae9d5e9 MKL |
487 | if (smap->bpf_ma) { |
488 | migrate_disable(); | |
489 | storage = bpf_mem_cache_alloc_flags(&smap->storage_ma, gfp_flags); | |
490 | migrate_enable(); | |
491 | } else { | |
492 | storage = bpf_map_kzalloc(&smap->map, sizeof(*storage), | |
493 | gfp_flags | __GFP_NOWARN); | |
494 | } | |
495 | ||
450af8d0 KS |
496 | if (!storage) { |
497 | err = -ENOMEM; | |
498 | goto uncharge; | |
499 | } | |
500 | ||
fc6652aa | 501 | RCU_INIT_POINTER(storage->smap, smap); |
450af8d0 KS |
502 | INIT_HLIST_HEAD(&storage->list); |
503 | raw_spin_lock_init(&storage->lock); | |
504 | storage->owner = owner; | |
505 | ||
506 | bpf_selem_link_storage_nolock(storage, first_selem); | |
507 | bpf_selem_link_map(smap, first_selem); | |
508 | ||
509 | owner_storage_ptr = | |
510 | (struct bpf_local_storage **)owner_storage(smap, owner); | |
511 | /* Publish storage to the owner. | |
512 | * Instead of using any lock of the kernel object (i.e. owner), | |
513 | * cmpxchg will work with any kernel object regardless what | |
514 | * the running context is, bh, irq...etc. | |
515 | * | |
516 | * From now on, the owner->storage pointer (e.g. sk->sk_bpf_storage) | |
517 | * is protected by the storage->lock. Hence, when freeing | |
518 | * the owner->storage, the storage->lock must be held before | |
519 | * setting owner->storage ptr to NULL. | |
520 | */ | |
521 | prev_storage = cmpxchg(owner_storage_ptr, NULL, storage); | |
522 | if (unlikely(prev_storage)) { | |
523 | bpf_selem_unlink_map(first_selem); | |
524 | err = -EAGAIN; | |
525 | goto uncharge; | |
526 | ||
527 | /* Note that even first_selem was linked to smap's | |
528 | * bucket->list, first_selem can be freed immediately | |
529 | * (instead of kfree_rcu) because | |
530 | * bpf_local_storage_map_free() does a | |
0fe4b381 KS |
531 | * synchronize_rcu_mult (waiting for both sleepable and |
532 | * normal programs) before walking the bucket->list. | |
450af8d0 KS |
533 | * Hence, no one is accessing selem from the |
534 | * bucket->list under rcu_read_lock(). | |
535 | */ | |
536 | } | |
537 | ||
538 | return 0; | |
539 | ||
540 | uncharge: | |
6ae9d5e9 | 541 | bpf_local_storage_free(storage, smap, smap->bpf_ma, true); |
450af8d0 KS |
542 | mem_uncharge(smap, owner, sizeof(*storage)); |
543 | return err; | |
544 | } | |
545 | ||
546 | /* sk cannot be going away because it is linking new elem | |
547 | * to sk->sk_bpf_storage. (i.e. sk->sk_refcnt cannot be 0). | |
548 | * Otherwise, it will become a leak (and other memory issues | |
549 | * during map destruction). | |
550 | */ | |
551 | struct bpf_local_storage_data * | |
552 | bpf_local_storage_update(void *owner, struct bpf_local_storage_map *smap, | |
b00fa38a | 553 | void *value, u64 map_flags, gfp_t gfp_flags) |
450af8d0 KS |
554 | { |
555 | struct bpf_local_storage_data *old_sdata = NULL; | |
b00fa38a | 556 | struct bpf_local_storage_elem *selem = NULL; |
450af8d0 | 557 | struct bpf_local_storage *local_storage; |
a10787e6 | 558 | unsigned long flags; |
450af8d0 KS |
559 | int err; |
560 | ||
561 | /* BPF_EXIST and BPF_NOEXIST cannot be both set */ | |
562 | if (unlikely((map_flags & ~BPF_F_LOCK) > BPF_EXIST) || | |
563 | /* BPF_F_LOCK can only be used in a value with spin_lock */ | |
564 | unlikely((map_flags & BPF_F_LOCK) && | |
db559117 | 565 | !btf_record_has_field(smap->map.record, BPF_SPIN_LOCK))) |
450af8d0 KS |
566 | return ERR_PTR(-EINVAL); |
567 | ||
b00fa38a JK |
568 | if (gfp_flags == GFP_KERNEL && (map_flags & ~BPF_F_LOCK) != BPF_NOEXIST) |
569 | return ERR_PTR(-EINVAL); | |
570 | ||
0fe4b381 KS |
571 | local_storage = rcu_dereference_check(*owner_storage(smap, owner), |
572 | bpf_rcu_lock_held()); | |
450af8d0 KS |
573 | if (!local_storage || hlist_empty(&local_storage->list)) { |
574 | /* Very first elem for the owner */ | |
575 | err = check_flags(NULL, map_flags); | |
576 | if (err) | |
577 | return ERR_PTR(err); | |
578 | ||
b00fa38a | 579 | selem = bpf_selem_alloc(smap, owner, value, true, gfp_flags); |
450af8d0 KS |
580 | if (!selem) |
581 | return ERR_PTR(-ENOMEM); | |
582 | ||
b00fa38a | 583 | err = bpf_local_storage_alloc(owner, smap, selem, gfp_flags); |
450af8d0 | 584 | if (err) { |
c0d63f30 | 585 | bpf_selem_free(selem, smap, true); |
450af8d0 KS |
586 | mem_uncharge(smap, owner, smap->elem_size); |
587 | return ERR_PTR(err); | |
588 | } | |
589 | ||
590 | return SDATA(selem); | |
591 | } | |
592 | ||
593 | if ((map_flags & BPF_F_LOCK) && !(map_flags & BPF_NOEXIST)) { | |
594 | /* Hoping to find an old_sdata to do inline update | |
595 | * such that it can avoid taking the local_storage->lock | |
596 | * and changing the lists. | |
597 | */ | |
598 | old_sdata = | |
599 | bpf_local_storage_lookup(local_storage, smap, false); | |
600 | err = check_flags(old_sdata, map_flags); | |
601 | if (err) | |
602 | return ERR_PTR(err); | |
0a09a2f9 | 603 | if (old_sdata && selem_linked_to_storage_lockless(SELEM(old_sdata))) { |
450af8d0 KS |
604 | copy_map_value_locked(&smap->map, old_sdata->data, |
605 | value, false); | |
606 | return old_sdata; | |
607 | } | |
608 | } | |
609 | ||
b00fa38a JK |
610 | if (gfp_flags == GFP_KERNEL) { |
611 | selem = bpf_selem_alloc(smap, owner, value, true, gfp_flags); | |
612 | if (!selem) | |
613 | return ERR_PTR(-ENOMEM); | |
614 | } | |
615 | ||
a10787e6 | 616 | raw_spin_lock_irqsave(&local_storage->lock, flags); |
450af8d0 KS |
617 | |
618 | /* Recheck local_storage->list under local_storage->lock */ | |
619 | if (unlikely(hlist_empty(&local_storage->list))) { | |
620 | /* A parallel del is happening and local_storage is going | |
621 | * away. It has just been checked before, so very | |
622 | * unlikely. Return instead of retry to keep things | |
623 | * simple. | |
624 | */ | |
625 | err = -EAGAIN; | |
626 | goto unlock_err; | |
627 | } | |
628 | ||
629 | old_sdata = bpf_local_storage_lookup(local_storage, smap, false); | |
630 | err = check_flags(old_sdata, map_flags); | |
631 | if (err) | |
632 | goto unlock_err; | |
633 | ||
634 | if (old_sdata && (map_flags & BPF_F_LOCK)) { | |
635 | copy_map_value_locked(&smap->map, old_sdata->data, value, | |
636 | false); | |
637 | selem = SELEM(old_sdata); | |
638 | goto unlock; | |
639 | } | |
640 | ||
b00fa38a JK |
641 | if (gfp_flags != GFP_KERNEL) { |
642 | /* local_storage->lock is held. Hence, we are sure | |
643 | * we can unlink and uncharge the old_sdata successfully | |
644 | * later. Hence, instead of charging the new selem now | |
645 | * and then uncharge the old selem later (which may cause | |
646 | * a potential but unnecessary charge failure), avoid taking | |
647 | * a charge at all here (the "!old_sdata" check) and the | |
648 | * old_sdata will not be uncharged later during | |
649 | * bpf_selem_unlink_storage_nolock(). | |
650 | */ | |
651 | selem = bpf_selem_alloc(smap, owner, value, !old_sdata, gfp_flags); | |
652 | if (!selem) { | |
653 | err = -ENOMEM; | |
654 | goto unlock_err; | |
655 | } | |
450af8d0 KS |
656 | } |
657 | ||
658 | /* First, link the new selem to the map */ | |
659 | bpf_selem_link_map(smap, selem); | |
660 | ||
661 | /* Second, link (and publish) the new selem to local_storage */ | |
662 | bpf_selem_link_storage_nolock(local_storage, selem); | |
663 | ||
664 | /* Third, remove old selem, SELEM(old_sdata) */ | |
665 | if (old_sdata) { | |
666 | bpf_selem_unlink_map(SELEM(old_sdata)); | |
667 | bpf_selem_unlink_storage_nolock(local_storage, SELEM(old_sdata), | |
a47eabf2 | 668 | false, false); |
450af8d0 KS |
669 | } |
670 | ||
671 | unlock: | |
a10787e6 | 672 | raw_spin_unlock_irqrestore(&local_storage->lock, flags); |
450af8d0 KS |
673 | return SDATA(selem); |
674 | ||
675 | unlock_err: | |
a10787e6 | 676 | raw_spin_unlock_irqrestore(&local_storage->lock, flags); |
b00fa38a JK |
677 | if (selem) { |
678 | mem_uncharge(smap, owner, smap->elem_size); | |
c0d63f30 | 679 | bpf_selem_free(selem, smap, true); |
b00fa38a | 680 | } |
450af8d0 KS |
681 | return ERR_PTR(err); |
682 | } | |
683 | ||
c83597fa | 684 | static u16 bpf_local_storage_cache_idx_get(struct bpf_local_storage_cache *cache) |
450af8d0 KS |
685 | { |
686 | u64 min_usage = U64_MAX; | |
687 | u16 i, res = 0; | |
688 | ||
689 | spin_lock(&cache->idx_lock); | |
690 | ||
691 | for (i = 0; i < BPF_LOCAL_STORAGE_CACHE_SIZE; i++) { | |
692 | if (cache->idx_usage_counts[i] < min_usage) { | |
693 | min_usage = cache->idx_usage_counts[i]; | |
694 | res = i; | |
695 | ||
696 | /* Found a free cache_idx */ | |
697 | if (!min_usage) | |
698 | break; | |
699 | } | |
700 | } | |
701 | cache->idx_usage_counts[res]++; | |
702 | ||
703 | spin_unlock(&cache->idx_lock); | |
704 | ||
705 | return res; | |
706 | } | |
707 | ||
c83597fa YS |
708 | static void bpf_local_storage_cache_idx_free(struct bpf_local_storage_cache *cache, |
709 | u16 idx) | |
450af8d0 KS |
710 | { |
711 | spin_lock(&cache->idx_lock); | |
712 | cache->idx_usage_counts[idx]--; | |
713 | spin_unlock(&cache->idx_lock); | |
714 | } | |
715 | ||
450af8d0 KS |
716 | int bpf_local_storage_map_alloc_check(union bpf_attr *attr) |
717 | { | |
718 | if (attr->map_flags & ~BPF_LOCAL_STORAGE_CREATE_FLAG_MASK || | |
719 | !(attr->map_flags & BPF_F_NO_PREALLOC) || | |
720 | attr->max_entries || | |
721 | attr->key_size != sizeof(int) || !attr->value_size || | |
722 | /* Enforce BTF for userspace sk dumping */ | |
723 | !attr->btf_key_type_id || !attr->btf_value_type_id) | |
724 | return -EINVAL; | |
725 | ||
726 | if (!bpf_capable()) | |
727 | return -EPERM; | |
728 | ||
729 | if (attr->value_size > BPF_LOCAL_STORAGE_MAX_VALUE_SIZE) | |
730 | return -E2BIG; | |
731 | ||
732 | return 0; | |
733 | } | |
734 | ||
450af8d0 KS |
735 | int bpf_local_storage_map_check_btf(const struct bpf_map *map, |
736 | const struct btf *btf, | |
737 | const struct btf_type *key_type, | |
738 | const struct btf_type *value_type) | |
739 | { | |
740 | u32 int_data; | |
741 | ||
742 | if (BTF_INFO_KIND(key_type->info) != BTF_KIND_INT) | |
743 | return -EINVAL; | |
744 | ||
745 | int_data = *(u32 *)(key_type + 1); | |
746 | if (BTF_INT_BITS(int_data) != 32 || BTF_INT_OFFSET(int_data)) | |
747 | return -EINVAL; | |
748 | ||
749 | return 0; | |
750 | } | |
c83597fa | 751 | |
2ffcb6fc | 752 | void bpf_local_storage_destroy(struct bpf_local_storage *local_storage) |
c83597fa | 753 | { |
6ae9d5e9 | 754 | struct bpf_local_storage_map *storage_smap; |
c83597fa | 755 | struct bpf_local_storage_elem *selem; |
6ae9d5e9 | 756 | bool bpf_ma, free_storage = false; |
c83597fa | 757 | struct hlist_node *n; |
2ffcb6fc | 758 | unsigned long flags; |
c83597fa | 759 | |
6ae9d5e9 MKL |
760 | storage_smap = rcu_dereference_check(local_storage->smap, bpf_rcu_lock_held()); |
761 | bpf_ma = check_storage_bpf_ma(local_storage, storage_smap, NULL); | |
762 | ||
c83597fa YS |
763 | /* Neither the bpf_prog nor the bpf_map's syscall |
764 | * could be modifying the local_storage->list now. | |
765 | * Thus, no elem can be added to or deleted from the | |
766 | * local_storage->list by the bpf_prog or by the bpf_map's syscall. | |
767 | * | |
768 | * It is racing with bpf_local_storage_map_free() alone | |
769 | * when unlinking elem from the local_storage->list and | |
770 | * the map's bucket->list. | |
771 | */ | |
2ffcb6fc | 772 | raw_spin_lock_irqsave(&local_storage->lock, flags); |
c83597fa YS |
773 | hlist_for_each_entry_safe(selem, n, &local_storage->list, snode) { |
774 | /* Always unlink from map before unlinking from | |
775 | * local_storage. | |
776 | */ | |
777 | bpf_selem_unlink_map(selem); | |
778 | /* If local_storage list has only one element, the | |
779 | * bpf_selem_unlink_storage_nolock() will return true. | |
780 | * Otherwise, it will return false. The current loop iteration | |
781 | * intends to remove all local storage. So the last iteration | |
782 | * of the loop will set the free_cgroup_storage to true. | |
783 | */ | |
784 | free_storage = bpf_selem_unlink_storage_nolock( | |
a47eabf2 | 785 | local_storage, selem, false, true); |
c83597fa | 786 | } |
2ffcb6fc | 787 | raw_spin_unlock_irqrestore(&local_storage->lock, flags); |
c83597fa | 788 | |
2ffcb6fc | 789 | if (free_storage) |
6ae9d5e9 | 790 | bpf_local_storage_free(local_storage, storage_smap, bpf_ma, true); |
c83597fa YS |
791 | } |
792 | ||
7490b7f1 YS |
793 | u64 bpf_local_storage_map_mem_usage(const struct bpf_map *map) |
794 | { | |
795 | struct bpf_local_storage_map *smap = (struct bpf_local_storage_map *)map; | |
796 | u64 usage = sizeof(*smap); | |
797 | ||
798 | /* The dynamically callocated selems are not counted currently. */ | |
799 | usage += sizeof(*smap->buckets) * (1ULL << smap->bucket_log); | |
800 | return usage; | |
801 | } | |
802 | ||
08a7ce38 MKL |
803 | /* When bpf_ma == true, the bpf_mem_alloc is used to allocate and free memory. |
804 | * A deadlock free allocator is useful for storage that the bpf prog can easily | |
805 | * get a hold of the owner PTR_TO_BTF_ID in any context. eg. bpf_get_current_task_btf. | |
806 | * The task and cgroup storage fall into this case. The bpf_mem_alloc reuses | |
807 | * memory immediately. To be reuse-immediate safe, the owner destruction | |
808 | * code path needs to go through a rcu grace period before calling | |
809 | * bpf_local_storage_destroy(). | |
810 | * | |
811 | * When bpf_ma == false, the kmalloc and kfree are used. | |
812 | */ | |
c83597fa YS |
813 | struct bpf_map * |
814 | bpf_local_storage_map_alloc(union bpf_attr *attr, | |
08a7ce38 MKL |
815 | struct bpf_local_storage_cache *cache, |
816 | bool bpf_ma) | |
c83597fa YS |
817 | { |
818 | struct bpf_local_storage_map *smap; | |
62827d61 MKL |
819 | unsigned int i; |
820 | u32 nbuckets; | |
08a7ce38 | 821 | int err; |
62827d61 MKL |
822 | |
823 | smap = bpf_map_area_alloc(sizeof(*smap), NUMA_NO_NODE); | |
824 | if (!smap) | |
825 | return ERR_PTR(-ENOMEM); | |
826 | bpf_map_init_from_attr(&smap->map, attr); | |
827 | ||
828 | nbuckets = roundup_pow_of_two(num_possible_cpus()); | |
829 | /* Use at least 2 buckets, select_bucket() is undefined behavior with 1 bucket */ | |
830 | nbuckets = max_t(u32, 2, nbuckets); | |
831 | smap->bucket_log = ilog2(nbuckets); | |
c83597fa | 832 | |
62827d61 MKL |
833 | smap->buckets = bpf_map_kvcalloc(&smap->map, sizeof(*smap->buckets), |
834 | nbuckets, GFP_USER | __GFP_NOWARN); | |
835 | if (!smap->buckets) { | |
08a7ce38 MKL |
836 | err = -ENOMEM; |
837 | goto free_smap; | |
62827d61 MKL |
838 | } |
839 | ||
840 | for (i = 0; i < nbuckets; i++) { | |
841 | INIT_HLIST_HEAD(&smap->buckets[i].list); | |
842 | raw_spin_lock_init(&smap->buckets[i].lock); | |
843 | } | |
844 | ||
845 | smap->elem_size = offsetof(struct bpf_local_storage_elem, | |
846 | sdata.data[attr->value_size]); | |
c83597fa | 847 | |
08a7ce38 MKL |
848 | smap->bpf_ma = bpf_ma; |
849 | if (bpf_ma) { | |
850 | err = bpf_mem_alloc_init(&smap->selem_ma, smap->elem_size, false); | |
851 | if (err) | |
852 | goto free_smap; | |
6ae9d5e9 MKL |
853 | |
854 | err = bpf_mem_alloc_init(&smap->storage_ma, sizeof(struct bpf_local_storage), false); | |
855 | if (err) { | |
856 | bpf_mem_alloc_destroy(&smap->selem_ma); | |
857 | goto free_smap; | |
858 | } | |
08a7ce38 MKL |
859 | } |
860 | ||
c83597fa YS |
861 | smap->cache_idx = bpf_local_storage_cache_idx_get(cache); |
862 | return &smap->map; | |
08a7ce38 MKL |
863 | |
864 | free_smap: | |
865 | kvfree(smap->buckets); | |
866 | bpf_map_area_free(smap); | |
867 | return ERR_PTR(err); | |
c83597fa YS |
868 | } |
869 | ||
870 | void bpf_local_storage_map_free(struct bpf_map *map, | |
871 | struct bpf_local_storage_cache *cache, | |
872 | int __percpu *busy_counter) | |
873 | { | |
874 | struct bpf_local_storage_map_bucket *b; | |
875 | struct bpf_local_storage_elem *selem; | |
876 | struct bpf_local_storage_map *smap; | |
877 | unsigned int i; | |
878 | ||
879 | smap = (struct bpf_local_storage_map *)map; | |
880 | bpf_local_storage_cache_idx_free(cache, smap->cache_idx); | |
881 | ||
882 | /* Note that this map might be concurrently cloned from | |
883 | * bpf_sk_storage_clone. Wait for any existing bpf_sk_storage_clone | |
884 | * RCU read section to finish before proceeding. New RCU | |
885 | * read sections should be prevented via bpf_map_inc_not_zero. | |
886 | */ | |
887 | synchronize_rcu(); | |
888 | ||
889 | /* bpf prog and the userspace can no longer access this map | |
890 | * now. No new selem (of this map) can be added | |
891 | * to the owner->storage or to the map bucket's list. | |
892 | * | |
893 | * The elem of this map can be cleaned up here | |
894 | * or when the storage is freed e.g. | |
895 | * by bpf_sk_storage_free() during __sk_destruct(). | |
896 | */ | |
897 | for (i = 0; i < (1U << smap->bucket_log); i++) { | |
898 | b = &smap->buckets[i]; | |
899 | ||
900 | rcu_read_lock(); | |
901 | /* No one is adding to b->list now */ | |
902 | while ((selem = hlist_entry_safe( | |
903 | rcu_dereference_raw(hlist_first_rcu(&b->list)), | |
904 | struct bpf_local_storage_elem, map_node))) { | |
905 | if (busy_counter) { | |
906 | migrate_disable(); | |
907 | this_cpu_inc(*busy_counter); | |
908 | } | |
a47eabf2 | 909 | bpf_selem_unlink(selem, true); |
c83597fa YS |
910 | if (busy_counter) { |
911 | this_cpu_dec(*busy_counter); | |
912 | migrate_enable(); | |
913 | } | |
914 | cond_resched_rcu(); | |
915 | } | |
916 | rcu_read_unlock(); | |
917 | } | |
918 | ||
919 | /* While freeing the storage we may still need to access the map. | |
920 | * | |
921 | * e.g. when bpf_sk_storage_free() has unlinked selem from the map | |
922 | * which then made the above while((selem = ...)) loop | |
923 | * exit immediately. | |
924 | * | |
925 | * However, while freeing the storage one still needs to access the | |
926 | * smap->elem_size to do the uncharging in | |
927 | * bpf_selem_unlink_storage_nolock(). | |
928 | * | |
929 | * Hence, wait another rcu grace period for the storage to be freed. | |
930 | */ | |
931 | synchronize_rcu(); | |
932 | ||
6ae9d5e9 | 933 | if (smap->bpf_ma) { |
08a7ce38 | 934 | bpf_mem_alloc_destroy(&smap->selem_ma); |
6ae9d5e9 MKL |
935 | bpf_mem_alloc_destroy(&smap->storage_ma); |
936 | } | |
c83597fa YS |
937 | kvfree(smap->buckets); |
938 | bpf_map_area_free(smap); | |
939 | } |