1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * INET An implementation of the TCP/IP protocol suite for the LINUX
4 * operating system. INET is implemented using the BSD Socket
5 * interface as the means of communication with the user level.
6 *
7 * Support for INET connection oriented protocols.
8 *
9 * Authors: See the TCP sources
10 */
11
12 #include <linux/module.h>
13 #include <linux/jhash.h>
14
15 #include <net/inet_connection_sock.h>
16 #include <net/inet_hashtables.h>
17 #include <net/inet_timewait_sock.h>
18 #include <net/ip.h>
19 #include <net/route.h>
20 #include <net/tcp_states.h>
21 #include <net/xfrm.h>
22 #include <net/tcp.h>
23 #include <net/sock_reuseport.h>
24 #include <net/addrconf.h>
25
26 #if IS_ENABLED(CONFIG_IPV6)
27 /* match_sk*_wildcard == true: IPV6_ADDR_ANY equals to any IPv6 addresses
28 * if IPv6 only, and any IPv4 addresses
29 * if not IPv6 only
30 * match_sk*_wildcard == false: addresses must be exactly the same, i.e.
31 * IPV6_ADDR_ANY only equals to IPV6_ADDR_ANY,
32 * and 0.0.0.0 equals to 0.0.0.0 only
33 */
ipv6_rcv_saddr_equal(const struct in6_addr *sk1_rcv_saddr6, const struct in6_addr *sk2_rcv_saddr6, __be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr, bool sk1_ipv6only, bool sk2_ipv6only, bool match_sk1_wildcard, bool match_sk2_wildcard)34 static bool ipv6_rcv_saddr_equal(const struct in6_addr *sk1_rcv_saddr6,
35 const struct in6_addr *sk2_rcv_saddr6,
36 __be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr,
37 bool sk1_ipv6only, bool sk2_ipv6only,
38 bool match_sk1_wildcard,
39 bool match_sk2_wildcard)
40 {
41 int addr_type = ipv6_addr_type(sk1_rcv_saddr6);
42 int addr_type2 = sk2_rcv_saddr6 ? ipv6_addr_type(sk2_rcv_saddr6) : IPV6_ADDR_MAPPED;
43
44 /* if both are mapped, treat as IPv4 */
45 if (addr_type == IPV6_ADDR_MAPPED && addr_type2 == IPV6_ADDR_MAPPED) {
46 if (!sk2_ipv6only) {
47 if (sk1_rcv_saddr == sk2_rcv_saddr)
48 return true;
49 return (match_sk1_wildcard && !sk1_rcv_saddr) ||
50 (match_sk2_wildcard && !sk2_rcv_saddr);
51 }
52 return false;
53 }
54
55 if (addr_type == IPV6_ADDR_ANY && addr_type2 == IPV6_ADDR_ANY)
56 return true;
57
58 if (addr_type2 == IPV6_ADDR_ANY && match_sk2_wildcard &&
59 !(sk2_ipv6only && addr_type == IPV6_ADDR_MAPPED))
60 return true;
61
62 if (addr_type == IPV6_ADDR_ANY && match_sk1_wildcard &&
63 !(sk1_ipv6only && addr_type2 == IPV6_ADDR_MAPPED))
64 return true;
65
66 if (sk2_rcv_saddr6 &&
67 ipv6_addr_equal(sk1_rcv_saddr6, sk2_rcv_saddr6))
68 return true;
69
70 return false;
71 }
72 #endif
73
74 /* match_sk*_wildcard == true: 0.0.0.0 equals to any IPv4 addresses
75 * match_sk*_wildcard == false: addresses must be exactly the same, i.e.
76 * 0.0.0.0 only equals to 0.0.0.0
77 */
ipv4_rcv_saddr_equal(__be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr, bool sk2_ipv6only, bool match_sk1_wildcard, bool match_sk2_wildcard)78 static bool ipv4_rcv_saddr_equal(__be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr,
79 bool sk2_ipv6only, bool match_sk1_wildcard,
80 bool match_sk2_wildcard)
81 {
82 if (!sk2_ipv6only) {
83 if (sk1_rcv_saddr == sk2_rcv_saddr)
84 return true;
85 return (match_sk1_wildcard && !sk1_rcv_saddr) ||
86 (match_sk2_wildcard && !sk2_rcv_saddr);
87 }
88 return false;
89 }
90
inet_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2, bool match_wildcard)91 bool inet_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2,
92 bool match_wildcard)
93 {
94 #if IS_ENABLED(CONFIG_IPV6)
95 if (sk->sk_family == AF_INET6)
96 return ipv6_rcv_saddr_equal(&sk->sk_v6_rcv_saddr,
97 inet6_rcv_saddr(sk2),
98 sk->sk_rcv_saddr,
99 sk2->sk_rcv_saddr,
100 ipv6_only_sock(sk),
101 ipv6_only_sock(sk2),
102 match_wildcard,
103 match_wildcard);
104 #endif
105
106 return ipv4_rcv_saddr_equal(sk->sk_rcv_saddr, sk2->sk_rcv_saddr,
107 ipv6_only_sock(sk2), match_wildcard,
108 match_wildcard);
109 }
110 EXPORT_SYMBOL(inet_rcv_saddr_equal);
111
inet_rcv_saddr_any(const struct sock *sk)112 bool inet_rcv_saddr_any(const struct sock *sk)
113 {
114 #if IS_ENABLED(CONFIG_IPV6)
115 if (sk->sk_family == AF_INET6)
116 return ipv6_addr_any(&sk->sk_v6_rcv_saddr);
117 #endif
118 return !sk->sk_rcv_saddr;
119 }
120
inet_get_local_port_range(struct net *net, int *low, int *high)121 void inet_get_local_port_range(struct net *net, int *low, int *high)
122 {
123 unsigned int seq;
124
125 do {
126 seq = read_seqbegin(&net->ipv4.ip_local_ports.lock);
127
128 *low = net->ipv4.ip_local_ports.range[0];
129 *high = net->ipv4.ip_local_ports.range[1];
130 } while (read_seqretry(&net->ipv4.ip_local_ports.lock, seq));
131 }
132 EXPORT_SYMBOL(inet_get_local_port_range);
133
inet_csk_bind_conflict(const struct sock *sk, const struct inet_bind_bucket *tb, bool relax, bool reuseport_ok)134 static int inet_csk_bind_conflict(const struct sock *sk,
135 const struct inet_bind_bucket *tb,
136 bool relax, bool reuseport_ok)
137 {
138 struct sock *sk2;
139 bool reuse = sk->sk_reuse;
140 bool reuseport = !!sk->sk_reuseport;
141 kuid_t uid = sock_i_uid((struct sock *)sk);
142
143 /*
144 * Unlike other sk lookup places we do not check
145 * for sk_net here, since _all_ the socks listed
146 * in tb->owners list belong to the same net - the
147 * one this bucket belongs to.
148 */
149
150 sk_for_each_bound(sk2, &tb->owners) {
151 int bound_dev_if2;
152
153 if (sk == sk2)
154 continue;
155 bound_dev_if2 = READ_ONCE(sk2->sk_bound_dev_if);
156 if ((!sk->sk_bound_dev_if ||
157 !bound_dev_if2 ||
158 sk->sk_bound_dev_if == bound_dev_if2)) {
159 if (reuse && sk2->sk_reuse &&
160 sk2->sk_state != TCP_LISTEN) {
161 if ((!relax ||
162 (!reuseport_ok &&
163 reuseport && sk2->sk_reuseport &&
164 !rcu_access_pointer(sk->sk_reuseport_cb) &&
165 (sk2->sk_state == TCP_TIME_WAIT ||
166 uid_eq(uid, sock_i_uid(sk2))))) &&
167 inet_rcv_saddr_equal(sk, sk2, true))
168 break;
169 } else if (!reuseport_ok ||
170 !reuseport || !sk2->sk_reuseport ||
171 rcu_access_pointer(sk->sk_reuseport_cb) ||
172 (sk2->sk_state != TCP_TIME_WAIT &&
173 !uid_eq(uid, sock_i_uid(sk2)))) {
174 if (inet_rcv_saddr_equal(sk, sk2, true))
175 break;
176 }
177 }
178 }
179 return sk2 != NULL;
180 }
181
182 /*
183 * Find an open port number for the socket. Returns with the
184 * inet_bind_hashbucket lock held.
185 */
186 static struct inet_bind_hashbucket *
inet_csk_find_open_port(struct sock *sk, struct inet_bind_bucket **tb_ret, int *port_ret)187 inet_csk_find_open_port(struct sock *sk, struct inet_bind_bucket **tb_ret, int *port_ret)
188 {
189 struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
190 int port = 0;
191 struct inet_bind_hashbucket *head;
192 struct net *net = sock_net(sk);
193 bool relax = false;
194 int i, low, high, attempt_half;
195 struct inet_bind_bucket *tb;
196 u32 remaining, offset;
197 int l3mdev;
198
199 l3mdev = inet_sk_bound_l3mdev(sk);
200 ports_exhausted:
201 attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0;
202 other_half_scan:
203 inet_get_local_port_range(net, &low, &high);
204 high++; /* [32768, 60999] -> [32768, 61000[ */
205 if (high - low < 4)
206 attempt_half = 0;
207 if (attempt_half) {
208 int half = low + (((high - low) >> 2) << 1);
209
210 if (attempt_half == 1)
211 high = half;
212 else
213 low = half;
214 }
215 remaining = high - low;
216 if (likely(remaining > 1))
217 remaining &= ~1U;
218
219 offset = prandom_u32() % remaining;
220 /* __inet_hash_connect() favors ports having @low parity
221 * We do the opposite to not pollute connect() users.
222 */
223 offset |= 1U;
224
225 other_parity_scan:
226 port = low + offset;
227 for (i = 0; i < remaining; i += 2, port += 2) {
228 if (unlikely(port >= high))
229 port -= remaining;
230 if (inet_is_local_reserved_port(net, port))
231 continue;
232 head = &hinfo->bhash[inet_bhashfn(net, port,
233 hinfo->bhash_size)];
234 spin_lock_bh(&head->lock);
235 inet_bind_bucket_for_each(tb, &head->chain)
236 if (net_eq(ib_net(tb), net) && tb->l3mdev == l3mdev &&
237 tb->port == port) {
238 if (!inet_csk_bind_conflict(sk, tb, relax, false))
239 goto success;
240 goto next_port;
241 }
242 tb = NULL;
243 goto success;
244 next_port:
245 spin_unlock_bh(&head->lock);
246 cond_resched();
247 }
248
249 offset--;
250 if (!(offset & 1))
251 goto other_parity_scan;
252
253 if (attempt_half == 1) {
254 /* OK we now try the upper half of the range */
255 attempt_half = 2;
256 goto other_half_scan;
257 }
258
259 if (READ_ONCE(net->ipv4.sysctl_ip_autobind_reuse) && !relax) {
260 /* We still have a chance to connect to different destinations */
261 relax = true;
262 goto ports_exhausted;
263 }
264 return NULL;
265 success:
266 *port_ret = port;
267 *tb_ret = tb;
268 return head;
269 }
270
sk_reuseport_match(struct inet_bind_bucket *tb, struct sock *sk)271 static inline int sk_reuseport_match(struct inet_bind_bucket *tb,
272 struct sock *sk)
273 {
274 kuid_t uid = sock_i_uid(sk);
275
276 if (tb->fastreuseport <= 0)
277 return 0;
278 if (!sk->sk_reuseport)
279 return 0;
280 if (rcu_access_pointer(sk->sk_reuseport_cb))
281 return 0;
282 if (!uid_eq(tb->fastuid, uid))
283 return 0;
284 /* We only need to check the rcv_saddr if this tb was once marked
285 * without fastreuseport and then was reset, as we can only know that
286 * the fast_*rcv_saddr doesn't have any conflicts with the socks on the
287 * owners list.
288 */
289 if (tb->fastreuseport == FASTREUSEPORT_ANY)
290 return 1;
291 #if IS_ENABLED(CONFIG_IPV6)
292 if (tb->fast_sk_family == AF_INET6)
293 return ipv6_rcv_saddr_equal(&tb->fast_v6_rcv_saddr,
294 inet6_rcv_saddr(sk),
295 tb->fast_rcv_saddr,
296 sk->sk_rcv_saddr,
297 tb->fast_ipv6_only,
298 ipv6_only_sock(sk), true, false);
299 #endif
300 return ipv4_rcv_saddr_equal(tb->fast_rcv_saddr, sk->sk_rcv_saddr,
301 ipv6_only_sock(sk), true, false);
302 }
303
inet_csk_update_fastreuse(struct inet_bind_bucket *tb, struct sock *sk)304 void inet_csk_update_fastreuse(struct inet_bind_bucket *tb,
305 struct sock *sk)
306 {
307 kuid_t uid = sock_i_uid(sk);
308 bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
309
310 if (hlist_empty(&tb->owners)) {
311 tb->fastreuse = reuse;
312 if (sk->sk_reuseport) {
313 tb->fastreuseport = FASTREUSEPORT_ANY;
314 tb->fastuid = uid;
315 tb->fast_rcv_saddr = sk->sk_rcv_saddr;
316 tb->fast_ipv6_only = ipv6_only_sock(sk);
317 tb->fast_sk_family = sk->sk_family;
318 #if IS_ENABLED(CONFIG_IPV6)
319 tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
320 #endif
321 } else {
322 tb->fastreuseport = 0;
323 }
324 } else {
325 if (!reuse)
326 tb->fastreuse = 0;
327 if (sk->sk_reuseport) {
328 /* We didn't match or we don't have fastreuseport set on
329 * the tb, but we have sk_reuseport set on this socket
330 * and we know that there are no bind conflicts with
331 * this socket in this tb, so reset our tb's reuseport
332 * settings so that any subsequent sockets that match
333 * our current socket will be put on the fast path.
334 *
335 * If we reset we need to set FASTREUSEPORT_STRICT so we
336 * do extra checking for all subsequent sk_reuseport
337 * socks.
338 */
339 if (!sk_reuseport_match(tb, sk)) {
340 tb->fastreuseport = FASTREUSEPORT_STRICT;
341 tb->fastuid = uid;
342 tb->fast_rcv_saddr = sk->sk_rcv_saddr;
343 tb->fast_ipv6_only = ipv6_only_sock(sk);
344 tb->fast_sk_family = sk->sk_family;
345 #if IS_ENABLED(CONFIG_IPV6)
346 tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
347 #endif
348 }
349 } else {
350 tb->fastreuseport = 0;
351 }
352 }
353 }
354
355 /* Obtain a reference to a local port for the given sock,
356 * if snum is zero it means select any available local port.
357 * We try to allocate an odd port (and leave even ports for connect())
358 */
inet_csk_get_port(struct sock *sk, unsigned short snum)359 int inet_csk_get_port(struct sock *sk, unsigned short snum)
360 {
361 bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
362 struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
363 int ret = 1, port = snum;
364 struct inet_bind_hashbucket *head;
365 struct net *net = sock_net(sk);
366 struct inet_bind_bucket *tb = NULL;
367 int l3mdev;
368
369 l3mdev = inet_sk_bound_l3mdev(sk);
370
371 if (!port) {
372 head = inet_csk_find_open_port(sk, &tb, &port);
373 if (!head)
374 return ret;
375 if (!tb)
376 goto tb_not_found;
377 goto success;
378 }
379 head = &hinfo->bhash[inet_bhashfn(net, port,
380 hinfo->bhash_size)];
381 spin_lock_bh(&head->lock);
382 inet_bind_bucket_for_each(tb, &head->chain)
383 if (net_eq(ib_net(tb), net) && tb->l3mdev == l3mdev &&
384 tb->port == port)
385 goto tb_found;
386 tb_not_found:
387 tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
388 net, head, port, l3mdev);
389 if (!tb)
390 goto fail_unlock;
391 tb_found:
392 if (!hlist_empty(&tb->owners)) {
393 if (sk->sk_reuse == SK_FORCE_REUSE)
394 goto success;
395
396 if ((tb->fastreuse > 0 && reuse) ||
397 sk_reuseport_match(tb, sk))
398 goto success;
399 if (inet_csk_bind_conflict(sk, tb, true, true))
400 goto fail_unlock;
401 }
402 success:
403 inet_csk_update_fastreuse(tb, sk);
404
405 if (!inet_csk(sk)->icsk_bind_hash)
406 inet_bind_hash(sk, tb, port);
407 WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);
408 ret = 0;
409
410 fail_unlock:
411 spin_unlock_bh(&head->lock);
412 return ret;
413 }
414 EXPORT_SYMBOL_GPL(inet_csk_get_port);
415
416 /*
417 * Wait for an incoming connection, avoid race conditions. This must be called
418 * with the socket locked.
419 */
inet_csk_wait_for_connect(struct sock *sk, long timeo)420 static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
421 {
422 struct inet_connection_sock *icsk = inet_csk(sk);
423 DEFINE_WAIT(wait);
424 int err;
425
426 /*
427 * True wake-one mechanism for incoming connections: only
428 * one process gets woken up, not the 'whole herd'.
429 * Since we do not 'race & poll' for established sockets
430 * anymore, the common case will execute the loop only once.
431 *
432 * Subtle issue: "add_wait_queue_exclusive()" will be added
433 * after any current non-exclusive waiters, and we know that
434 * it will always _stay_ after any new non-exclusive waiters
435 * because all non-exclusive waiters are added at the
436 * beginning of the wait-queue. As such, it's ok to "drop"
437 * our exclusiveness temporarily when we get woken up without
438 * having to remove and re-insert us on the wait queue.
439 */
440 for (;;) {
441 prepare_to_wait_exclusive(sk_sleep(sk), &wait,
442 TASK_INTERRUPTIBLE);
443 release_sock(sk);
444 if (reqsk_queue_empty(&icsk->icsk_accept_queue))
445 timeo = schedule_timeout(timeo);
446 sched_annotate_sleep();
447 lock_sock(sk);
448 err = 0;
449 if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
450 break;
451 err = -EINVAL;
452 if (sk->sk_state != TCP_LISTEN)
453 break;
454 err = sock_intr_errno(timeo);
455 if (signal_pending(current))
456 break;
457 err = -EAGAIN;
458 if (!timeo)
459 break;
460 }
461 finish_wait(sk_sleep(sk), &wait);
462 return err;
463 }
464
465 /*
466 * This will accept the next outstanding connection.
467 */
inet_csk_accept(struct sock *sk, int flags, int *err, bool kern)468 struct sock *inet_csk_accept(struct sock *sk, int flags, int *err, bool kern)
469 {
470 struct inet_connection_sock *icsk = inet_csk(sk);
471 struct request_sock_queue *queue = &icsk->icsk_accept_queue;
472 struct request_sock *req;
473 struct sock *newsk;
474 int error;
475
476 lock_sock(sk);
477
478 /* We need to make sure that this socket is listening,
479 * and that it has something pending.
480 */
481 error = -EINVAL;
482 if (sk->sk_state != TCP_LISTEN)
483 goto out_err;
484
485 /* Find already established connection */
486 if (reqsk_queue_empty(queue)) {
487 long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
488
489 /* If this is a non blocking socket don't sleep */
490 error = -EAGAIN;
491 if (!timeo)
492 goto out_err;
493
494 error = inet_csk_wait_for_connect(sk, timeo);
495 if (error)
496 goto out_err;
497 }
498 req = reqsk_queue_remove(queue, sk);
499 newsk = req->sk;
500
501 if (sk->sk_protocol == IPPROTO_TCP &&
502 tcp_rsk(req)->tfo_listener) {
503 spin_lock_bh(&queue->fastopenq.lock);
504 if (tcp_rsk(req)->tfo_listener) {
505 /* We are still waiting for the final ACK from 3WHS
506 * so can't free req now. Instead, we set req->sk to
507 * NULL to signify that the child socket is taken
508 * so reqsk_fastopen_remove() will free the req
509 * when 3WHS finishes (or is aborted).
510 */
511 req->sk = NULL;
512 req = NULL;
513 }
514 spin_unlock_bh(&queue->fastopenq.lock);
515 }
516
517 out:
518 release_sock(sk);
519 if (newsk && mem_cgroup_sockets_enabled) {
520 int amt;
521
522 /* atomically get the memory usage, set and charge the
523 * newsk->sk_memcg.
524 */
525 lock_sock(newsk);
526
527 /* The socket has not been accepted yet, no need to look at
528 * newsk->sk_wmem_queued.
529 */
530 amt = sk_mem_pages(newsk->sk_forward_alloc +
531 atomic_read(&newsk->sk_rmem_alloc));
532 mem_cgroup_sk_alloc(newsk);
533 if (newsk->sk_memcg && amt)
534 mem_cgroup_charge_skmem(newsk->sk_memcg, amt);
535
536 release_sock(newsk);
537 }
538 if (req)
539 reqsk_put(req);
540
541 if (newsk)
542 inet_init_csk_locks(newsk);
543
544 return newsk;
545 out_err:
546 newsk = NULL;
547 req = NULL;
548 *err = error;
549 goto out;
550 }
551 EXPORT_SYMBOL(inet_csk_accept);
552
553 /*
554 * Using different timers for retransmit, delayed acks and probes
555 * We may wish use just one timer maintaining a list of expire jiffies
556 * to optimize.
557 */
inet_csk_init_xmit_timers(struct sock *sk, void (*retransmit_handler)(struct timer_list *t), void (*delack_handler)(struct timer_list *t), void (*keepalive_handler)(struct timer_list *t))558 void inet_csk_init_xmit_timers(struct sock *sk,
559 void (*retransmit_handler)(struct timer_list *t),
560 void (*delack_handler)(struct timer_list *t),
561 void (*keepalive_handler)(struct timer_list *t))
562 {
563 struct inet_connection_sock *icsk = inet_csk(sk);
564
565 timer_setup(&icsk->icsk_retransmit_timer, retransmit_handler, 0);
566 timer_setup(&icsk->icsk_delack_timer, delack_handler, 0);
567 timer_setup(&sk->sk_timer, keepalive_handler, 0);
568 icsk->icsk_pending = icsk->icsk_ack.pending = 0;
569 }
570 EXPORT_SYMBOL(inet_csk_init_xmit_timers);
571
inet_csk_clear_xmit_timers(struct sock *sk)572 void inet_csk_clear_xmit_timers(struct sock *sk)
573 {
574 struct inet_connection_sock *icsk = inet_csk(sk);
575
576 icsk->icsk_pending = icsk->icsk_ack.pending = 0;
577
578 sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
579 sk_stop_timer(sk, &icsk->icsk_delack_timer);
580 sk_stop_timer(sk, &sk->sk_timer);
581 }
582 EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
583
inet_csk_clear_xmit_timers_sync(struct sock *sk)584 void inet_csk_clear_xmit_timers_sync(struct sock *sk)
585 {
586 struct inet_connection_sock *icsk = inet_csk(sk);
587
588 /* ongoing timer handlers need to acquire socket lock. */
589 sock_not_owned_by_me(sk);
590
591 icsk->icsk_pending = icsk->icsk_ack.pending = 0;
592
593 sk_stop_timer_sync(sk, &icsk->icsk_retransmit_timer);
594 sk_stop_timer_sync(sk, &icsk->icsk_delack_timer);
595 sk_stop_timer_sync(sk, &sk->sk_timer);
596 }
597
inet_csk_delete_keepalive_timer(struct sock *sk)598 void inet_csk_delete_keepalive_timer(struct sock *sk)
599 {
600 sk_stop_timer(sk, &sk->sk_timer);
601 }
602 EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
603
inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)604 void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
605 {
606 sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
607 }
608 EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
609
inet_csk_route_req(const struct sock *sk, struct flowi4 *fl4, const struct request_sock *req)610 struct dst_entry *inet_csk_route_req(const struct sock *sk,
611 struct flowi4 *fl4,
612 const struct request_sock *req)
613 {
614 const struct inet_request_sock *ireq = inet_rsk(req);
615 struct net *net = read_pnet(&ireq->ireq_net);
616 struct ip_options_rcu *opt;
617 struct rtable *rt;
618
619 rcu_read_lock();
620 opt = rcu_dereference(ireq->ireq_opt);
621
622 flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
623 RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
624 sk->sk_protocol, inet_sk_flowi_flags(sk),
625 (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
626 ireq->ir_loc_addr, ireq->ir_rmt_port,
627 htons(ireq->ir_num), sk->sk_uid);
628 security_req_classify_flow(req, flowi4_to_flowi_common(fl4));
629 rt = ip_route_output_flow(net, fl4, sk);
630 if (IS_ERR(rt))
631 goto no_route;
632 if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
633 goto route_err;
634 rcu_read_unlock();
635 return &rt->dst;
636
637 route_err:
638 ip_rt_put(rt);
639 no_route:
640 rcu_read_unlock();
641 __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
642 return NULL;
643 }
644 EXPORT_SYMBOL_GPL(inet_csk_route_req);
645
inet_csk_route_child_sock(const struct sock *sk, struct sock *newsk, const struct request_sock *req)646 struct dst_entry *inet_csk_route_child_sock(const struct sock *sk,
647 struct sock *newsk,
648 const struct request_sock *req)
649 {
650 const struct inet_request_sock *ireq = inet_rsk(req);
651 struct net *net = read_pnet(&ireq->ireq_net);
652 struct inet_sock *newinet = inet_sk(newsk);
653 struct ip_options_rcu *opt;
654 struct flowi4 *fl4;
655 struct rtable *rt;
656
657 opt = rcu_dereference(ireq->ireq_opt);
658 fl4 = &newinet->cork.fl.u.ip4;
659
660 flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
661 RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
662 sk->sk_protocol, inet_sk_flowi_flags(sk),
663 (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
664 ireq->ir_loc_addr, ireq->ir_rmt_port,
665 htons(ireq->ir_num), sk->sk_uid);
666 security_req_classify_flow(req, flowi4_to_flowi_common(fl4));
667 rt = ip_route_output_flow(net, fl4, sk);
668 if (IS_ERR(rt))
669 goto no_route;
670 if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
671 goto route_err;
672 return &rt->dst;
673
674 route_err:
675 ip_rt_put(rt);
676 no_route:
677 __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
678 return NULL;
679 }
680 EXPORT_SYMBOL_GPL(inet_csk_route_child_sock);
681
682 /* Decide when to expire the request and when to resend SYN-ACK */
syn_ack_recalc(struct request_sock *req, const int max_syn_ack_retries, const u8 rskq_defer_accept, int *expire, int *resend)683 static void syn_ack_recalc(struct request_sock *req,
684 const int max_syn_ack_retries,
685 const u8 rskq_defer_accept,
686 int *expire, int *resend)
687 {
688 if (!rskq_defer_accept) {
689 *expire = req->num_timeout >= max_syn_ack_retries;
690 *resend = 1;
691 return;
692 }
693 *expire = req->num_timeout >= max_syn_ack_retries &&
694 (!inet_rsk(req)->acked || req->num_timeout >= rskq_defer_accept);
695 /* Do not resend while waiting for data after ACK,
696 * start to resend on end of deferring period to give
697 * last chance for data or ACK to create established socket.
698 */
699 *resend = !inet_rsk(req)->acked ||
700 req->num_timeout >= rskq_defer_accept - 1;
701 }
702
inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req)703 int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req)
704 {
705 int err = req->rsk_ops->rtx_syn_ack(parent, req);
706
707 if (!err)
708 req->num_retrans++;
709 return err;
710 }
711 EXPORT_SYMBOL(inet_rtx_syn_ack);
712
713 /* return true if req was found in the ehash table */
reqsk_queue_unlink(struct request_sock *req)714 static bool reqsk_queue_unlink(struct request_sock *req)
715 {
716 struct inet_hashinfo *hashinfo = req_to_sk(req)->sk_prot->h.hashinfo;
717 bool found = false;
718
719 if (sk_hashed(req_to_sk(req))) {
720 spinlock_t *lock = inet_ehash_lockp(hashinfo, req->rsk_hash);
721
722 spin_lock(lock);
723 found = __sk_nulls_del_node_init_rcu(req_to_sk(req));
724 spin_unlock(lock);
725 }
726 if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer))
727 reqsk_put(req);
728 return found;
729 }
730
inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req)731 bool inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req)
732 {
733 bool unlinked = reqsk_queue_unlink(req);
734
735 if (unlinked) {
736 reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
737 reqsk_put(req);
738 }
739 return unlinked;
740 }
741 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop);
742
inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req)743 void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req)
744 {
745 inet_csk_reqsk_queue_drop(sk, req);
746 reqsk_put(req);
747 }
748 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop_and_put);
749
reqsk_timer_handler(struct timer_list *t)750 static void reqsk_timer_handler(struct timer_list *t)
751 {
752 struct request_sock *req = from_timer(req, t, rsk_timer);
753 struct sock *sk_listener = req->rsk_listener;
754 struct net *net = sock_net(sk_listener);
755 struct inet_connection_sock *icsk = inet_csk(sk_listener);
756 struct request_sock_queue *queue = &icsk->icsk_accept_queue;
757 int max_syn_ack_retries, qlen, expire = 0, resend = 0;
758
759 if (inet_sk_state_load(sk_listener) != TCP_LISTEN)
760 goto drop;
761
762 max_syn_ack_retries = READ_ONCE(icsk->icsk_syn_retries) ? :
763 READ_ONCE(net->ipv4.sysctl_tcp_synack_retries);
764 /* Normally all the openreqs are young and become mature
765 * (i.e. converted to established socket) for first timeout.
766 * If synack was not acknowledged for 1 second, it means
767 * one of the following things: synack was lost, ack was lost,
768 * rtt is high or nobody planned to ack (i.e. synflood).
769 * When server is a bit loaded, queue is populated with old
770 * open requests, reducing effective size of queue.
771 * When server is well loaded, queue size reduces to zero
772 * after several minutes of work. It is not synflood,
773 * it is normal operation. The solution is pruning
774 * too old entries overriding normal timeout, when
775 * situation becomes dangerous.
776 *
777 * Essentially, we reserve half of room for young
778 * embrions; and abort old ones without pity, if old
779 * ones are about to clog our table.
780 */
781 qlen = reqsk_queue_len(queue);
782 if ((qlen << 1) > max(8U, READ_ONCE(sk_listener->sk_max_ack_backlog))) {
783 int young = reqsk_queue_len_young(queue) << 1;
784
785 while (max_syn_ack_retries > 2) {
786 if (qlen < young)
787 break;
788 max_syn_ack_retries--;
789 young <<= 1;
790 }
791 }
792 syn_ack_recalc(req, max_syn_ack_retries, READ_ONCE(queue->rskq_defer_accept),
793 &expire, &resend);
794 req->rsk_ops->syn_ack_timeout(req);
795 if (!expire &&
796 (!resend ||
797 !inet_rtx_syn_ack(sk_listener, req) ||
798 inet_rsk(req)->acked)) {
799 unsigned long timeo;
800
801 if (req->num_timeout++ == 0)
802 atomic_dec(&queue->young);
803 timeo = min(TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX);
804 mod_timer(&req->rsk_timer, jiffies + timeo);
805 return;
806 }
807 drop:
808 inet_csk_reqsk_queue_drop_and_put(sk_listener, req);
809 }
810
reqsk_queue_hash_req(struct request_sock *req, unsigned long timeout)811 static void reqsk_queue_hash_req(struct request_sock *req,
812 unsigned long timeout)
813 {
814 timer_setup(&req->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
815 mod_timer(&req->rsk_timer, jiffies + timeout);
816
817 inet_ehash_insert(req_to_sk(req), NULL, NULL);
818 /* before letting lookups find us, make sure all req fields
819 * are committed to memory and refcnt initialized.
820 */
821 smp_wmb();
822 refcount_set(&req->rsk_refcnt, 2 + 1);
823 }
824
inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req, unsigned long timeout)825 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
826 unsigned long timeout)
827 {
828 reqsk_queue_hash_req(req, timeout);
829 inet_csk_reqsk_queue_added(sk);
830 }
831 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
832
inet_clone_ulp(const struct request_sock *req, struct sock *newsk, const gfp_t priority)833 static void inet_clone_ulp(const struct request_sock *req, struct sock *newsk,
834 const gfp_t priority)
835 {
836 struct inet_connection_sock *icsk = inet_csk(newsk);
837
838 if (!icsk->icsk_ulp_ops)
839 return;
840
841 icsk->icsk_ulp_ops->clone(req, newsk, priority);
842 }
843
844 /**
845 * inet_csk_clone_lock - clone an inet socket, and lock its clone
846 * @sk: the socket to clone
847 * @req: request_sock
848 * @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
849 *
850 * Caller must unlock socket even in error path (bh_unlock_sock(newsk))
851 */
inet_csk_clone_lock(const struct sock *sk, const struct request_sock *req, const gfp_t priority)852 struct sock *inet_csk_clone_lock(const struct sock *sk,
853 const struct request_sock *req,
854 const gfp_t priority)
855 {
856 struct sock *newsk = sk_clone_lock(sk, priority);
857
858 if (newsk) {
859 struct inet_connection_sock *newicsk = inet_csk(newsk);
860
861 newsk->sk_wait_pending = 0;
862 inet_sk_set_state(newsk, TCP_SYN_RECV);
863 newicsk->icsk_bind_hash = NULL;
864
865 inet_sk(newsk)->inet_dport = inet_rsk(req)->ir_rmt_port;
866 inet_sk(newsk)->inet_num = inet_rsk(req)->ir_num;
867 inet_sk(newsk)->inet_sport = htons(inet_rsk(req)->ir_num);
868
869 /* listeners have SOCK_RCU_FREE, not the children */
870 sock_reset_flag(newsk, SOCK_RCU_FREE);
871
872 inet_sk(newsk)->mc_list = NULL;
873
874 newsk->sk_mark = inet_rsk(req)->ir_mark;
875 atomic64_set(&newsk->sk_cookie,
876 atomic64_read(&inet_rsk(req)->ir_cookie));
877
878 newicsk->icsk_retransmits = 0;
879 newicsk->icsk_backoff = 0;
880 newicsk->icsk_probes_out = 0;
881 newicsk->icsk_probes_tstamp = 0;
882
883 /* Deinitialize accept_queue to trap illegal accesses. */
884 memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
885
886 inet_clone_ulp(req, newsk, priority);
887
888 security_inet_csk_clone(newsk, req);
889 }
890 return newsk;
891 }
892 EXPORT_SYMBOL_GPL(inet_csk_clone_lock);
893
894 /*
895 * At this point, there should be no process reference to this
896 * socket, and thus no user references at all. Therefore we
897 * can assume the socket waitqueue is inactive and nobody will
898 * try to jump onto it.
899 */
inet_csk_destroy_sock(struct sock *sk)900 void inet_csk_destroy_sock(struct sock *sk)
901 {
902 WARN_ON(sk->sk_state != TCP_CLOSE);
903 WARN_ON(!sock_flag(sk, SOCK_DEAD));
904
905 /* It cannot be in hash table! */
906 WARN_ON(!sk_unhashed(sk));
907
908 /* If it has not 0 inet_sk(sk)->inet_num, it must be bound */
909 WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash);
910
911 sk->sk_prot->destroy(sk);
912
913 sk_stream_kill_queues(sk);
914
915 xfrm_sk_free_policy(sk);
916
917 sk_refcnt_debug_release(sk);
918
919 this_cpu_dec(*sk->sk_prot->orphan_count);
920
921 sock_put(sk);
922 }
923 EXPORT_SYMBOL(inet_csk_destroy_sock);
924
925 /* This function allows to force a closure of a socket after the call to
926 * tcp/dccp_create_openreq_child().
927 */
928 void inet_csk_prepare_forced_close(struct sock *sk)
929 __releases(&sk->sk_lock.slock)
930 {
931 /* sk_clone_lock locked the socket and set refcnt to 2 */
932 bh_unlock_sock(sk);
933 sock_put(sk);
934 inet_csk_prepare_for_destroy_sock(sk);
935 inet_sk(sk)->inet_num = 0;
936 }
937 EXPORT_SYMBOL(inet_csk_prepare_forced_close);
938
inet_ulp_can_listen(const struct sock *sk)939 static int inet_ulp_can_listen(const struct sock *sk)
940 {
941 const struct inet_connection_sock *icsk = inet_csk(sk);
942
943 if (icsk->icsk_ulp_ops && !icsk->icsk_ulp_ops->clone)
944 return -EINVAL;
945
946 return 0;
947 }
948
inet_csk_listen_start(struct sock *sk, int backlog)949 int inet_csk_listen_start(struct sock *sk, int backlog)
950 {
951 struct inet_connection_sock *icsk = inet_csk(sk);
952 struct inet_sock *inet = inet_sk(sk);
953 int err;
954
955 err = inet_ulp_can_listen(sk);
956 if (unlikely(err))
957 return err;
958
959 reqsk_queue_alloc(&icsk->icsk_accept_queue);
960
961 sk->sk_ack_backlog = 0;
962 inet_csk_delack_init(sk);
963
964 /* There is race window here: we announce ourselves listening,
965 * but this transition is still not validated by get_port().
966 * It is OK, because this socket enters to hash table only
967 * after validation is complete.
968 */
969 err = -EADDRINUSE;
970 inet_sk_state_store(sk, TCP_LISTEN);
971 if (!sk->sk_prot->get_port(sk, inet->inet_num)) {
972 inet->inet_sport = htons(inet->inet_num);
973
974 sk_dst_reset(sk);
975 err = sk->sk_prot->hash(sk);
976
977 if (likely(!err))
978 return 0;
979 }
980
981 inet_sk_set_state(sk, TCP_CLOSE);
982 return err;
983 }
984 EXPORT_SYMBOL_GPL(inet_csk_listen_start);
985
inet_child_forget(struct sock *sk, struct request_sock *req, struct sock *child)986 static void inet_child_forget(struct sock *sk, struct request_sock *req,
987 struct sock *child)
988 {
989 sk->sk_prot->disconnect(child, O_NONBLOCK);
990
991 sock_orphan(child);
992
993 this_cpu_inc(*sk->sk_prot->orphan_count);
994
995 if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->tfo_listener) {
996 BUG_ON(rcu_access_pointer(tcp_sk(child)->fastopen_rsk) != req);
997 BUG_ON(sk != req->rsk_listener);
998
999 /* Paranoid, to prevent race condition if
1000 * an inbound pkt destined for child is
1001 * blocked by sock lock in tcp_v4_rcv().
1002 * Also to satisfy an assertion in
1003 * tcp_v4_destroy_sock().
1004 */
1005 RCU_INIT_POINTER(tcp_sk(child)->fastopen_rsk, NULL);
1006 }
1007 inet_csk_destroy_sock(child);
1008 }
1009
inet_csk_reqsk_queue_add(struct sock *sk, struct request_sock *req, struct sock *child)1010 struct sock *inet_csk_reqsk_queue_add(struct sock *sk,
1011 struct request_sock *req,
1012 struct sock *child)
1013 {
1014 struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
1015
1016 spin_lock(&queue->rskq_lock);
1017 if (unlikely(sk->sk_state != TCP_LISTEN)) {
1018 inet_child_forget(sk, req, child);
1019 child = NULL;
1020 } else {
1021 req->sk = child;
1022 req->dl_next = NULL;
1023 if (queue->rskq_accept_head == NULL)
1024 WRITE_ONCE(queue->rskq_accept_head, req);
1025 else
1026 queue->rskq_accept_tail->dl_next = req;
1027 queue->rskq_accept_tail = req;
1028 sk_acceptq_added(sk);
1029 }
1030 spin_unlock(&queue->rskq_lock);
1031 return child;
1032 }
1033 EXPORT_SYMBOL(inet_csk_reqsk_queue_add);
1034
inet_csk_complete_hashdance(struct sock *sk, struct sock *child, struct request_sock *req, bool own_req)1035 struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child,
1036 struct request_sock *req, bool own_req)
1037 {
1038 if (own_req) {
1039 inet_csk_reqsk_queue_drop(sk, req);
1040 reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
1041 if (inet_csk_reqsk_queue_add(sk, req, child))
1042 return child;
1043 }
1044 /* Too bad, another child took ownership of the request, undo. */
1045 bh_unlock_sock(child);
1046 sock_put(child);
1047 return NULL;
1048 }
1049 EXPORT_SYMBOL(inet_csk_complete_hashdance);
1050
1051 /*
1052 * This routine closes sockets which have been at least partially
1053 * opened, but not yet accepted.
1054 */
inet_csk_listen_stop(struct sock *sk)1055 void inet_csk_listen_stop(struct sock *sk)
1056 {
1057 struct inet_connection_sock *icsk = inet_csk(sk);
1058 struct request_sock_queue *queue = &icsk->icsk_accept_queue;
1059 struct request_sock *next, *req;
1060
1061 /* Following specs, it would be better either to send FIN
1062 * (and enter FIN-WAIT-1, it is normal close)
1063 * or to send active reset (abort).
1064 * Certainly, it is pretty dangerous while synflood, but it is
1065 * bad justification for our negligence 8)
1066 * To be honest, we are not able to make either
1067 * of the variants now. --ANK
1068 */
1069 while ((req = reqsk_queue_remove(queue, sk)) != NULL) {
1070 struct sock *child = req->sk;
1071
1072 local_bh_disable();
1073 bh_lock_sock(child);
1074 WARN_ON(sock_owned_by_user(child));
1075 sock_hold(child);
1076
1077 inet_child_forget(sk, req, child);
1078 reqsk_put(req);
1079 bh_unlock_sock(child);
1080 local_bh_enable();
1081 sock_put(child);
1082
1083 cond_resched();
1084 }
1085 if (queue->fastopenq.rskq_rst_head) {
1086 /* Free all the reqs queued in rskq_rst_head. */
1087 spin_lock_bh(&queue->fastopenq.lock);
1088 req = queue->fastopenq.rskq_rst_head;
1089 queue->fastopenq.rskq_rst_head = NULL;
1090 spin_unlock_bh(&queue->fastopenq.lock);
1091 while (req != NULL) {
1092 next = req->dl_next;
1093 reqsk_put(req);
1094 req = next;
1095 }
1096 }
1097 WARN_ON_ONCE(sk->sk_ack_backlog);
1098 }
1099 EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
1100
inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)1101 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
1102 {
1103 struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
1104 const struct inet_sock *inet = inet_sk(sk);
1105
1106 sin->sin_family = AF_INET;
1107 sin->sin_addr.s_addr = inet->inet_daddr;
1108 sin->sin_port = inet->inet_dport;
1109 }
1110 EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);
1111
inet_csk_rebuild_route(struct sock *sk, struct flowi *fl)1112 static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *fl)
1113 {
1114 const struct inet_sock *inet = inet_sk(sk);
1115 const struct ip_options_rcu *inet_opt;
1116 __be32 daddr = inet->inet_daddr;
1117 struct flowi4 *fl4;
1118 struct rtable *rt;
1119
1120 rcu_read_lock();
1121 inet_opt = rcu_dereference(inet->inet_opt);
1122 if (inet_opt && inet_opt->opt.srr)
1123 daddr = inet_opt->opt.faddr;
1124 fl4 = &fl->u.ip4;
1125 rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr,
1126 inet->inet_saddr, inet->inet_dport,
1127 inet->inet_sport, sk->sk_protocol,
1128 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
1129 if (IS_ERR(rt))
1130 rt = NULL;
1131 if (rt)
1132 sk_setup_caps(sk, &rt->dst);
1133 rcu_read_unlock();
1134
1135 return &rt->dst;
1136 }
1137
inet_csk_update_pmtu(struct sock *sk, u32 mtu)1138 struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu)
1139 {
1140 struct dst_entry *dst = __sk_dst_check(sk, 0);
1141 struct inet_sock *inet = inet_sk(sk);
1142
1143 if (!dst) {
1144 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1145 if (!dst)
1146 goto out;
1147 }
1148 dst->ops->update_pmtu(dst, sk, NULL, mtu, true);
1149
1150 dst = __sk_dst_check(sk, 0);
1151 if (!dst)
1152 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1153 out:
1154 return dst;
1155 }
1156 EXPORT_SYMBOL_GPL(inet_csk_update_pmtu);
1157