1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * To speed up listener socket lookup, create an array to store all sockets |
4 | * listening on the same port. This allows a decision to be made after finding |
5 | * the first socket. An optional BPF program can also be configured for |
6 | * selecting the socket index from the array of available sockets. |
7 | */ |
8 | |
9 | #include <net/ip.h> |
10 | #include <net/sock_reuseport.h> |
11 | #include <linux/bpf.h> |
12 | #include <linux/idr.h> |
13 | #include <linux/filter.h> |
14 | #include <linux/rcupdate.h> |
15 | |
16 | #define INIT_SOCKS 128 |
17 | |
18 | DEFINE_SPINLOCK(reuseport_lock); |
19 | |
20 | static DEFINE_IDA(reuseport_ida); |
21 | static int reuseport_resurrect(struct sock *sk, struct sock_reuseport *old_reuse, |
22 | struct sock_reuseport *reuse, bool bind_inany); |
23 | |
24 | void reuseport_has_conns_set(struct sock *sk) |
25 | { |
26 | struct sock_reuseport *reuse; |
27 | |
28 | if (!rcu_access_pointer(sk->sk_reuseport_cb)) |
29 | return; |
30 | |
31 | spin_lock_bh(lock: &reuseport_lock); |
32 | reuse = rcu_dereference_protected(sk->sk_reuseport_cb, |
33 | lockdep_is_held(&reuseport_lock)); |
34 | if (likely(reuse)) |
35 | reuse->has_conns = 1; |
36 | spin_unlock_bh(lock: &reuseport_lock); |
37 | } |
38 | EXPORT_SYMBOL(reuseport_has_conns_set); |
39 | |
40 | static void __reuseport_get_incoming_cpu(struct sock_reuseport *reuse) |
41 | { |
42 | /* Paired with READ_ONCE() in reuseport_select_sock_by_hash(). */ |
43 | WRITE_ONCE(reuse->incoming_cpu, reuse->incoming_cpu + 1); |
44 | } |
45 | |
46 | static void __reuseport_put_incoming_cpu(struct sock_reuseport *reuse) |
47 | { |
48 | /* Paired with READ_ONCE() in reuseport_select_sock_by_hash(). */ |
49 | WRITE_ONCE(reuse->incoming_cpu, reuse->incoming_cpu - 1); |
50 | } |
51 | |
52 | static void reuseport_get_incoming_cpu(struct sock *sk, struct sock_reuseport *reuse) |
53 | { |
54 | if (sk->sk_incoming_cpu >= 0) |
55 | __reuseport_get_incoming_cpu(reuse); |
56 | } |
57 | |
58 | static void reuseport_put_incoming_cpu(struct sock *sk, struct sock_reuseport *reuse) |
59 | { |
60 | if (sk->sk_incoming_cpu >= 0) |
61 | __reuseport_put_incoming_cpu(reuse); |
62 | } |
63 | |
64 | void reuseport_update_incoming_cpu(struct sock *sk, int val) |
65 | { |
66 | struct sock_reuseport *reuse; |
67 | int old_sk_incoming_cpu; |
68 | |
69 | if (unlikely(!rcu_access_pointer(sk->sk_reuseport_cb))) { |
70 | /* Paired with REAE_ONCE() in sk_incoming_cpu_update() |
71 | * and compute_score(). |
72 | */ |
73 | WRITE_ONCE(sk->sk_incoming_cpu, val); |
74 | return; |
75 | } |
76 | |
77 | spin_lock_bh(lock: &reuseport_lock); |
78 | |
79 | /* This must be done under reuseport_lock to avoid a race with |
80 | * reuseport_grow(), which accesses sk->sk_incoming_cpu without |
81 | * lock_sock() when detaching a shutdown()ed sk. |
82 | * |
83 | * Paired with READ_ONCE() in reuseport_select_sock_by_hash(). |
84 | */ |
85 | old_sk_incoming_cpu = sk->sk_incoming_cpu; |
86 | WRITE_ONCE(sk->sk_incoming_cpu, val); |
87 | |
88 | reuse = rcu_dereference_protected(sk->sk_reuseport_cb, |
89 | lockdep_is_held(&reuseport_lock)); |
90 | |
91 | /* reuseport_grow() has detached a closed sk. */ |
92 | if (!reuse) |
93 | goto out; |
94 | |
95 | if (old_sk_incoming_cpu < 0 && val >= 0) |
96 | __reuseport_get_incoming_cpu(reuse); |
97 | else if (old_sk_incoming_cpu >= 0 && val < 0) |
98 | __reuseport_put_incoming_cpu(reuse); |
99 | |
100 | out: |
101 | spin_unlock_bh(lock: &reuseport_lock); |
102 | } |
103 | |
104 | static int reuseport_sock_index(struct sock *sk, |
105 | const struct sock_reuseport *reuse, |
106 | bool closed) |
107 | { |
108 | int left, right; |
109 | |
110 | if (!closed) { |
111 | left = 0; |
112 | right = reuse->num_socks; |
113 | } else { |
114 | left = reuse->max_socks - reuse->num_closed_socks; |
115 | right = reuse->max_socks; |
116 | } |
117 | |
118 | for (; left < right; left++) |
119 | if (reuse->socks[left] == sk) |
120 | return left; |
121 | return -1; |
122 | } |
123 | |
124 | static void __reuseport_add_sock(struct sock *sk, |
125 | struct sock_reuseport *reuse) |
126 | { |
127 | reuse->socks[reuse->num_socks] = sk; |
128 | /* paired with smp_rmb() in reuseport_(select|migrate)_sock() */ |
129 | smp_wmb(); |
130 | reuse->num_socks++; |
131 | reuseport_get_incoming_cpu(sk, reuse); |
132 | } |
133 | |
134 | static bool __reuseport_detach_sock(struct sock *sk, |
135 | struct sock_reuseport *reuse) |
136 | { |
137 | int i = reuseport_sock_index(sk, reuse, closed: false); |
138 | |
139 | if (i == -1) |
140 | return false; |
141 | |
142 | reuse->socks[i] = reuse->socks[reuse->num_socks - 1]; |
143 | reuse->num_socks--; |
144 | reuseport_put_incoming_cpu(sk, reuse); |
145 | |
146 | return true; |
147 | } |
148 | |
149 | static void __reuseport_add_closed_sock(struct sock *sk, |
150 | struct sock_reuseport *reuse) |
151 | { |
152 | reuse->socks[reuse->max_socks - reuse->num_closed_socks - 1] = sk; |
153 | /* paired with READ_ONCE() in inet_csk_bind_conflict() */ |
154 | WRITE_ONCE(reuse->num_closed_socks, reuse->num_closed_socks + 1); |
155 | reuseport_get_incoming_cpu(sk, reuse); |
156 | } |
157 | |
158 | static bool __reuseport_detach_closed_sock(struct sock *sk, |
159 | struct sock_reuseport *reuse) |
160 | { |
161 | int i = reuseport_sock_index(sk, reuse, closed: true); |
162 | |
163 | if (i == -1) |
164 | return false; |
165 | |
166 | reuse->socks[i] = reuse->socks[reuse->max_socks - reuse->num_closed_socks]; |
167 | /* paired with READ_ONCE() in inet_csk_bind_conflict() */ |
168 | WRITE_ONCE(reuse->num_closed_socks, reuse->num_closed_socks - 1); |
169 | reuseport_put_incoming_cpu(sk, reuse); |
170 | |
171 | return true; |
172 | } |
173 | |
174 | static struct sock_reuseport *__reuseport_alloc(unsigned int max_socks) |
175 | { |
176 | unsigned int size = sizeof(struct sock_reuseport) + |
177 | sizeof(struct sock *) * max_socks; |
178 | struct sock_reuseport *reuse = kzalloc(size, GFP_ATOMIC); |
179 | |
180 | if (!reuse) |
181 | return NULL; |
182 | |
183 | reuse->max_socks = max_socks; |
184 | |
185 | RCU_INIT_POINTER(reuse->prog, NULL); |
186 | return reuse; |
187 | } |
188 | |
189 | int reuseport_alloc(struct sock *sk, bool bind_inany) |
190 | { |
191 | struct sock_reuseport *reuse; |
192 | int id, ret = 0; |
193 | |
194 | /* bh lock used since this function call may precede hlist lock in |
195 | * soft irq of receive path or setsockopt from process context |
196 | */ |
197 | spin_lock_bh(lock: &reuseport_lock); |
198 | |
199 | /* Allocation attempts can occur concurrently via the setsockopt path |
200 | * and the bind/hash path. Nothing to do when we lose the race. |
201 | */ |
202 | reuse = rcu_dereference_protected(sk->sk_reuseport_cb, |
203 | lockdep_is_held(&reuseport_lock)); |
204 | if (reuse) { |
205 | if (reuse->num_closed_socks) { |
206 | /* sk was shutdown()ed before */ |
207 | ret = reuseport_resurrect(sk, old_reuse: reuse, NULL, bind_inany); |
208 | goto out; |
209 | } |
210 | |
211 | /* Only set reuse->bind_inany if the bind_inany is true. |
212 | * Otherwise, it will overwrite the reuse->bind_inany |
213 | * which was set by the bind/hash path. |
214 | */ |
215 | if (bind_inany) |
216 | reuse->bind_inany = bind_inany; |
217 | goto out; |
218 | } |
219 | |
220 | reuse = __reuseport_alloc(INIT_SOCKS); |
221 | if (!reuse) { |
222 | ret = -ENOMEM; |
223 | goto out; |
224 | } |
225 | |
226 | id = ida_alloc(ida: &reuseport_ida, GFP_ATOMIC); |
227 | if (id < 0) { |
228 | kfree(objp: reuse); |
229 | ret = id; |
230 | goto out; |
231 | } |
232 | |
233 | reuse->reuseport_id = id; |
234 | reuse->bind_inany = bind_inany; |
235 | reuse->socks[0] = sk; |
236 | reuse->num_socks = 1; |
237 | reuseport_get_incoming_cpu(sk, reuse); |
238 | rcu_assign_pointer(sk->sk_reuseport_cb, reuse); |
239 | |
240 | out: |
241 | spin_unlock_bh(lock: &reuseport_lock); |
242 | |
243 | return ret; |
244 | } |
245 | EXPORT_SYMBOL(reuseport_alloc); |
246 | |
247 | static struct sock_reuseport *reuseport_grow(struct sock_reuseport *reuse) |
248 | { |
249 | struct sock_reuseport *more_reuse; |
250 | u32 more_socks_size, i; |
251 | |
252 | more_socks_size = reuse->max_socks * 2U; |
253 | if (more_socks_size > U16_MAX) { |
254 | if (reuse->num_closed_socks) { |
255 | /* Make room by removing a closed sk. |
256 | * The child has already been migrated. |
257 | * Only reqsk left at this point. |
258 | */ |
259 | struct sock *sk; |
260 | |
261 | sk = reuse->socks[reuse->max_socks - reuse->num_closed_socks]; |
262 | RCU_INIT_POINTER(sk->sk_reuseport_cb, NULL); |
263 | __reuseport_detach_closed_sock(sk, reuse); |
264 | |
265 | return reuse; |
266 | } |
267 | |
268 | return NULL; |
269 | } |
270 | |
271 | more_reuse = __reuseport_alloc(max_socks: more_socks_size); |
272 | if (!more_reuse) |
273 | return NULL; |
274 | |
275 | more_reuse->num_socks = reuse->num_socks; |
276 | more_reuse->num_closed_socks = reuse->num_closed_socks; |
277 | more_reuse->prog = reuse->prog; |
278 | more_reuse->reuseport_id = reuse->reuseport_id; |
279 | more_reuse->bind_inany = reuse->bind_inany; |
280 | more_reuse->has_conns = reuse->has_conns; |
281 | more_reuse->incoming_cpu = reuse->incoming_cpu; |
282 | |
283 | memcpy(more_reuse->socks, reuse->socks, |
284 | reuse->num_socks * sizeof(struct sock *)); |
285 | memcpy(more_reuse->socks + |
286 | (more_reuse->max_socks - more_reuse->num_closed_socks), |
287 | reuse->socks + (reuse->max_socks - reuse->num_closed_socks), |
288 | reuse->num_closed_socks * sizeof(struct sock *)); |
289 | more_reuse->synq_overflow_ts = READ_ONCE(reuse->synq_overflow_ts); |
290 | |
291 | for (i = 0; i < reuse->max_socks; ++i) |
292 | rcu_assign_pointer(reuse->socks[i]->sk_reuseport_cb, |
293 | more_reuse); |
294 | |
295 | /* Note: we use kfree_rcu here instead of reuseport_free_rcu so |
296 | * that reuse and more_reuse can temporarily share a reference |
297 | * to prog. |
298 | */ |
299 | kfree_rcu(reuse, rcu); |
300 | return more_reuse; |
301 | } |
302 | |
303 | static void reuseport_free_rcu(struct rcu_head *head) |
304 | { |
305 | struct sock_reuseport *reuse; |
306 | |
307 | reuse = container_of(head, struct sock_reuseport, rcu); |
308 | sk_reuseport_prog_free(rcu_dereference_protected(reuse->prog, 1)); |
309 | ida_free(&reuseport_ida, id: reuse->reuseport_id); |
310 | kfree(objp: reuse); |
311 | } |
312 | |
313 | /** |
314 | * reuseport_add_sock - Add a socket to the reuseport group of another. |
315 | * @sk: New socket to add to the group. |
316 | * @sk2: Socket belonging to the existing reuseport group. |
317 | * @bind_inany: Whether or not the group is bound to a local INANY address. |
318 | * |
319 | * May return ENOMEM and not add socket to group under memory pressure. |
320 | */ |
321 | int reuseport_add_sock(struct sock *sk, struct sock *sk2, bool bind_inany) |
322 | { |
323 | struct sock_reuseport *old_reuse, *reuse; |
324 | |
325 | if (!rcu_access_pointer(sk2->sk_reuseport_cb)) { |
326 | int err = reuseport_alloc(sk2, bind_inany); |
327 | |
328 | if (err) |
329 | return err; |
330 | } |
331 | |
332 | spin_lock_bh(lock: &reuseport_lock); |
333 | reuse = rcu_dereference_protected(sk2->sk_reuseport_cb, |
334 | lockdep_is_held(&reuseport_lock)); |
335 | old_reuse = rcu_dereference_protected(sk->sk_reuseport_cb, |
336 | lockdep_is_held(&reuseport_lock)); |
337 | if (old_reuse && old_reuse->num_closed_socks) { |
338 | /* sk was shutdown()ed before */ |
339 | int err = reuseport_resurrect(sk, old_reuse, reuse, bind_inany: reuse->bind_inany); |
340 | |
341 | spin_unlock_bh(lock: &reuseport_lock); |
342 | return err; |
343 | } |
344 | |
345 | if (old_reuse && old_reuse->num_socks != 1) { |
346 | spin_unlock_bh(lock: &reuseport_lock); |
347 | return -EBUSY; |
348 | } |
349 | |
350 | if (reuse->num_socks + reuse->num_closed_socks == reuse->max_socks) { |
351 | reuse = reuseport_grow(reuse); |
352 | if (!reuse) { |
353 | spin_unlock_bh(lock: &reuseport_lock); |
354 | return -ENOMEM; |
355 | } |
356 | } |
357 | |
358 | __reuseport_add_sock(sk, reuse); |
359 | rcu_assign_pointer(sk->sk_reuseport_cb, reuse); |
360 | |
361 | spin_unlock_bh(lock: &reuseport_lock); |
362 | |
363 | if (old_reuse) |
364 | call_rcu(head: &old_reuse->rcu, func: reuseport_free_rcu); |
365 | return 0; |
366 | } |
367 | EXPORT_SYMBOL(reuseport_add_sock); |
368 | |
369 | static int reuseport_resurrect(struct sock *sk, struct sock_reuseport *old_reuse, |
370 | struct sock_reuseport *reuse, bool bind_inany) |
371 | { |
372 | if (old_reuse == reuse) { |
373 | /* If sk was in the same reuseport group, just pop sk out of |
374 | * the closed section and push sk into the listening section. |
375 | */ |
376 | __reuseport_detach_closed_sock(sk, reuse: old_reuse); |
377 | __reuseport_add_sock(sk, reuse: old_reuse); |
378 | return 0; |
379 | } |
380 | |
381 | if (!reuse) { |
382 | /* In bind()/listen() path, we cannot carry over the eBPF prog |
383 | * for the shutdown()ed socket. In setsockopt() path, we should |
384 | * not change the eBPF prog of listening sockets by attaching a |
385 | * prog to the shutdown()ed socket. Thus, we will allocate a new |
386 | * reuseport group and detach sk from the old group. |
387 | */ |
388 | int id; |
389 | |
390 | reuse = __reuseport_alloc(INIT_SOCKS); |
391 | if (!reuse) |
392 | return -ENOMEM; |
393 | |
394 | id = ida_alloc(ida: &reuseport_ida, GFP_ATOMIC); |
395 | if (id < 0) { |
396 | kfree(objp: reuse); |
397 | return id; |
398 | } |
399 | |
400 | reuse->reuseport_id = id; |
401 | reuse->bind_inany = bind_inany; |
402 | } else { |
403 | /* Move sk from the old group to the new one if |
404 | * - all the other listeners in the old group were close()d or |
405 | * shutdown()ed, and then sk2 has listen()ed on the same port |
406 | * OR |
407 | * - sk listen()ed without bind() (or with autobind), was |
408 | * shutdown()ed, and then listen()s on another port which |
409 | * sk2 listen()s on. |
410 | */ |
411 | if (reuse->num_socks + reuse->num_closed_socks == reuse->max_socks) { |
412 | reuse = reuseport_grow(reuse); |
413 | if (!reuse) |
414 | return -ENOMEM; |
415 | } |
416 | } |
417 | |
418 | __reuseport_detach_closed_sock(sk, reuse: old_reuse); |
419 | __reuseport_add_sock(sk, reuse); |
420 | rcu_assign_pointer(sk->sk_reuseport_cb, reuse); |
421 | |
422 | if (old_reuse->num_socks + old_reuse->num_closed_socks == 0) |
423 | call_rcu(head: &old_reuse->rcu, func: reuseport_free_rcu); |
424 | |
425 | return 0; |
426 | } |
427 | |
428 | void reuseport_detach_sock(struct sock *sk) |
429 | { |
430 | struct sock_reuseport *reuse; |
431 | |
432 | spin_lock_bh(lock: &reuseport_lock); |
433 | reuse = rcu_dereference_protected(sk->sk_reuseport_cb, |
434 | lockdep_is_held(&reuseport_lock)); |
435 | |
436 | /* reuseport_grow() has detached a closed sk */ |
437 | if (!reuse) |
438 | goto out; |
439 | |
440 | /* Notify the bpf side. The sk may be added to a sockarray |
441 | * map. If so, sockarray logic will remove it from the map. |
442 | * |
443 | * Other bpf map types that work with reuseport, like sockmap, |
444 | * don't need an explicit callback from here. They override sk |
445 | * unhash/close ops to remove the sk from the map before we |
446 | * get to this point. |
447 | */ |
448 | bpf_sk_reuseport_detach(sk); |
449 | |
450 | rcu_assign_pointer(sk->sk_reuseport_cb, NULL); |
451 | |
452 | if (!__reuseport_detach_closed_sock(sk, reuse)) |
453 | __reuseport_detach_sock(sk, reuse); |
454 | |
455 | if (reuse->num_socks + reuse->num_closed_socks == 0) |
456 | call_rcu(head: &reuse->rcu, func: reuseport_free_rcu); |
457 | |
458 | out: |
459 | spin_unlock_bh(lock: &reuseport_lock); |
460 | } |
461 | EXPORT_SYMBOL(reuseport_detach_sock); |
462 | |
463 | void reuseport_stop_listen_sock(struct sock *sk) |
464 | { |
465 | if (sk->sk_protocol == IPPROTO_TCP) { |
466 | struct sock_reuseport *reuse; |
467 | struct bpf_prog *prog; |
468 | |
469 | spin_lock_bh(lock: &reuseport_lock); |
470 | |
471 | reuse = rcu_dereference_protected(sk->sk_reuseport_cb, |
472 | lockdep_is_held(&reuseport_lock)); |
473 | prog = rcu_dereference_protected(reuse->prog, |
474 | lockdep_is_held(&reuseport_lock)); |
475 | |
476 | if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_migrate_req) || |
477 | (prog && prog->expected_attach_type == BPF_SK_REUSEPORT_SELECT_OR_MIGRATE)) { |
478 | /* Migration capable, move sk from the listening section |
479 | * to the closed section. |
480 | */ |
481 | bpf_sk_reuseport_detach(sk); |
482 | |
483 | __reuseport_detach_sock(sk, reuse); |
484 | __reuseport_add_closed_sock(sk, reuse); |
485 | |
486 | spin_unlock_bh(lock: &reuseport_lock); |
487 | return; |
488 | } |
489 | |
490 | spin_unlock_bh(lock: &reuseport_lock); |
491 | } |
492 | |
493 | /* Not capable to do migration, detach immediately */ |
494 | reuseport_detach_sock(sk); |
495 | } |
496 | EXPORT_SYMBOL(reuseport_stop_listen_sock); |
497 | |
498 | static struct sock *run_bpf_filter(struct sock_reuseport *reuse, u16 socks, |
499 | struct bpf_prog *prog, struct sk_buff *skb, |
500 | int hdr_len) |
501 | { |
502 | struct sk_buff *nskb = NULL; |
503 | u32 index; |
504 | |
505 | if (skb_shared(skb)) { |
506 | nskb = skb_clone(skb, GFP_ATOMIC); |
507 | if (!nskb) |
508 | return NULL; |
509 | skb = nskb; |
510 | } |
511 | |
512 | /* temporarily advance data past protocol header */ |
513 | if (!pskb_pull(skb, len: hdr_len)) { |
514 | kfree_skb(skb: nskb); |
515 | return NULL; |
516 | } |
517 | index = bpf_prog_run_save_cb(prog, skb); |
518 | __skb_push(skb, len: hdr_len); |
519 | |
520 | consume_skb(skb: nskb); |
521 | |
522 | if (index >= socks) |
523 | return NULL; |
524 | |
525 | return reuse->socks[index]; |
526 | } |
527 | |
528 | static struct sock *reuseport_select_sock_by_hash(struct sock_reuseport *reuse, |
529 | u32 hash, u16 num_socks) |
530 | { |
531 | struct sock *first_valid_sk = NULL; |
532 | int i, j; |
533 | |
534 | i = j = reciprocal_scale(val: hash, ep_ro: num_socks); |
535 | do { |
536 | struct sock *sk = reuse->socks[i]; |
537 | |
538 | if (sk->sk_state != TCP_ESTABLISHED) { |
539 | /* Paired with WRITE_ONCE() in __reuseport_(get|put)_incoming_cpu(). */ |
540 | if (!READ_ONCE(reuse->incoming_cpu)) |
541 | return sk; |
542 | |
543 | /* Paired with WRITE_ONCE() in reuseport_update_incoming_cpu(). */ |
544 | if (READ_ONCE(sk->sk_incoming_cpu) == raw_smp_processor_id()) |
545 | return sk; |
546 | |
547 | if (!first_valid_sk) |
548 | first_valid_sk = sk; |
549 | } |
550 | |
551 | i++; |
552 | if (i >= num_socks) |
553 | i = 0; |
554 | } while (i != j); |
555 | |
556 | return first_valid_sk; |
557 | } |
558 | |
559 | /** |
560 | * reuseport_select_sock - Select a socket from an SO_REUSEPORT group. |
561 | * @sk: First socket in the group. |
562 | * @hash: When no BPF filter is available, use this hash to select. |
563 | * @skb: skb to run through BPF filter. |
564 | * @hdr_len: BPF filter expects skb data pointer at payload data. If |
565 | * the skb does not yet point at the payload, this parameter represents |
566 | * how far the pointer needs to advance to reach the payload. |
567 | * Returns a socket that should receive the packet (or NULL on error). |
568 | */ |
569 | struct sock *reuseport_select_sock(struct sock *sk, |
570 | u32 hash, |
571 | struct sk_buff *skb, |
572 | int hdr_len) |
573 | { |
574 | struct sock_reuseport *reuse; |
575 | struct bpf_prog *prog; |
576 | struct sock *sk2 = NULL; |
577 | u16 socks; |
578 | |
579 | rcu_read_lock(); |
580 | reuse = rcu_dereference(sk->sk_reuseport_cb); |
581 | |
582 | /* if memory allocation failed or add call is not yet complete */ |
583 | if (!reuse) |
584 | goto out; |
585 | |
586 | prog = rcu_dereference(reuse->prog); |
587 | socks = READ_ONCE(reuse->num_socks); |
588 | if (likely(socks)) { |
589 | /* paired with smp_wmb() in __reuseport_add_sock() */ |
590 | smp_rmb(); |
591 | |
592 | if (!prog || !skb) |
593 | goto select_by_hash; |
594 | |
595 | if (prog->type == BPF_PROG_TYPE_SK_REUSEPORT) |
596 | sk2 = bpf_run_sk_reuseport(reuse, sk, prog, skb, NULL, hash); |
597 | else |
598 | sk2 = run_bpf_filter(reuse, socks, prog, skb, hdr_len); |
599 | |
600 | select_by_hash: |
601 | /* no bpf or invalid bpf result: fall back to hash usage */ |
602 | if (!sk2) |
603 | sk2 = reuseport_select_sock_by_hash(reuse, hash, num_socks: socks); |
604 | } |
605 | |
606 | out: |
607 | rcu_read_unlock(); |
608 | return sk2; |
609 | } |
610 | EXPORT_SYMBOL(reuseport_select_sock); |
611 | |
612 | /** |
613 | * reuseport_migrate_sock - Select a socket from an SO_REUSEPORT group. |
614 | * @sk: close()ed or shutdown()ed socket in the group. |
615 | * @migrating_sk: ESTABLISHED/SYN_RECV full socket in the accept queue or |
616 | * NEW_SYN_RECV request socket during 3WHS. |
617 | * @skb: skb to run through BPF filter. |
618 | * Returns a socket (with sk_refcnt +1) that should accept the child socket |
619 | * (or NULL on error). |
620 | */ |
621 | struct sock *reuseport_migrate_sock(struct sock *sk, |
622 | struct sock *migrating_sk, |
623 | struct sk_buff *skb) |
624 | { |
625 | struct sock_reuseport *reuse; |
626 | struct sock *nsk = NULL; |
627 | bool allocated = false; |
628 | struct bpf_prog *prog; |
629 | u16 socks; |
630 | u32 hash; |
631 | |
632 | rcu_read_lock(); |
633 | |
634 | reuse = rcu_dereference(sk->sk_reuseport_cb); |
635 | if (!reuse) |
636 | goto out; |
637 | |
638 | socks = READ_ONCE(reuse->num_socks); |
639 | if (unlikely(!socks)) |
640 | goto failure; |
641 | |
642 | /* paired with smp_wmb() in __reuseport_add_sock() */ |
643 | smp_rmb(); |
644 | |
645 | hash = migrating_sk->sk_hash; |
646 | prog = rcu_dereference(reuse->prog); |
647 | if (!prog || prog->expected_attach_type != BPF_SK_REUSEPORT_SELECT_OR_MIGRATE) { |
648 | if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_migrate_req)) |
649 | goto select_by_hash; |
650 | goto failure; |
651 | } |
652 | |
653 | if (!skb) { |
654 | skb = alloc_skb(size: 0, GFP_ATOMIC); |
655 | if (!skb) |
656 | goto failure; |
657 | allocated = true; |
658 | } |
659 | |
660 | nsk = bpf_run_sk_reuseport(reuse, sk, prog, skb, migrating_sk, hash); |
661 | |
662 | if (allocated) |
663 | kfree_skb(skb); |
664 | |
665 | select_by_hash: |
666 | if (!nsk) |
667 | nsk = reuseport_select_sock_by_hash(reuse, hash, num_socks: socks); |
668 | |
669 | if (IS_ERR_OR_NULL(ptr: nsk) || unlikely(!refcount_inc_not_zero(&nsk->sk_refcnt))) { |
670 | nsk = NULL; |
671 | goto failure; |
672 | } |
673 | |
674 | out: |
675 | rcu_read_unlock(); |
676 | return nsk; |
677 | |
678 | failure: |
679 | __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE); |
680 | goto out; |
681 | } |
682 | EXPORT_SYMBOL(reuseport_migrate_sock); |
683 | |
684 | int reuseport_attach_prog(struct sock *sk, struct bpf_prog *prog) |
685 | { |
686 | struct sock_reuseport *reuse; |
687 | struct bpf_prog *old_prog; |
688 | |
689 | if (sk_unhashed(sk)) { |
690 | int err; |
691 | |
692 | if (!sk->sk_reuseport) |
693 | return -EINVAL; |
694 | |
695 | err = reuseport_alloc(sk, false); |
696 | if (err) |
697 | return err; |
698 | } else if (!rcu_access_pointer(sk->sk_reuseport_cb)) { |
699 | /* The socket wasn't bound with SO_REUSEPORT */ |
700 | return -EINVAL; |
701 | } |
702 | |
703 | spin_lock_bh(lock: &reuseport_lock); |
704 | reuse = rcu_dereference_protected(sk->sk_reuseport_cb, |
705 | lockdep_is_held(&reuseport_lock)); |
706 | old_prog = rcu_dereference_protected(reuse->prog, |
707 | lockdep_is_held(&reuseport_lock)); |
708 | rcu_assign_pointer(reuse->prog, prog); |
709 | spin_unlock_bh(lock: &reuseport_lock); |
710 | |
711 | sk_reuseport_prog_free(prog: old_prog); |
712 | return 0; |
713 | } |
714 | EXPORT_SYMBOL(reuseport_attach_prog); |
715 | |
716 | int reuseport_detach_prog(struct sock *sk) |
717 | { |
718 | struct sock_reuseport *reuse; |
719 | struct bpf_prog *old_prog; |
720 | |
721 | old_prog = NULL; |
722 | spin_lock_bh(lock: &reuseport_lock); |
723 | reuse = rcu_dereference_protected(sk->sk_reuseport_cb, |
724 | lockdep_is_held(&reuseport_lock)); |
725 | |
726 | /* reuse must be checked after acquiring the reuseport_lock |
727 | * because reuseport_grow() can detach a closed sk. |
728 | */ |
729 | if (!reuse) { |
730 | spin_unlock_bh(lock: &reuseport_lock); |
731 | return sk->sk_reuseport ? -ENOENT : -EINVAL; |
732 | } |
733 | |
734 | if (sk_unhashed(sk) && reuse->num_closed_socks) { |
735 | spin_unlock_bh(lock: &reuseport_lock); |
736 | return -ENOENT; |
737 | } |
738 | |
739 | old_prog = rcu_replace_pointer(reuse->prog, old_prog, |
740 | lockdep_is_held(&reuseport_lock)); |
741 | spin_unlock_bh(lock: &reuseport_lock); |
742 | |
743 | if (!old_prog) |
744 | return -ENOENT; |
745 | |
746 | sk_reuseport_prog_free(prog: old_prog); |
747 | return 0; |
748 | } |
749 | EXPORT_SYMBOL(reuseport_detach_prog); |
750 | |