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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_delete_keepalive_timer(struct sock * sk)584 void inet_csk_delete_keepalive_timer(struct sock *sk)
585 {
586 	sk_stop_timer(sk, &sk->sk_timer);
587 }
588 EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
589 
inet_csk_reset_keepalive_timer(struct sock * sk,unsigned long len)590 void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
591 {
592 	sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
593 }
594 EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
595 
inet_csk_route_req(const struct sock * sk,struct flowi4 * fl4,const struct request_sock * req)596 struct dst_entry *inet_csk_route_req(const struct sock *sk,
597 				     struct flowi4 *fl4,
598 				     const struct request_sock *req)
599 {
600 	const struct inet_request_sock *ireq = inet_rsk(req);
601 	struct net *net = read_pnet(&ireq->ireq_net);
602 	struct ip_options_rcu *opt;
603 	struct rtable *rt;
604 
605 	rcu_read_lock();
606 	opt = rcu_dereference(ireq->ireq_opt);
607 
608 	flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
609 			   RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
610 			   sk->sk_protocol, inet_sk_flowi_flags(sk),
611 			   (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
612 			   ireq->ir_loc_addr, ireq->ir_rmt_port,
613 			   htons(ireq->ir_num), sk->sk_uid);
614 	security_req_classify_flow(req, flowi4_to_flowi_common(fl4));
615 	rt = ip_route_output_flow(net, fl4, sk);
616 	if (IS_ERR(rt))
617 		goto no_route;
618 	if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
619 		goto route_err;
620 	rcu_read_unlock();
621 	return &rt->dst;
622 
623 route_err:
624 	ip_rt_put(rt);
625 no_route:
626 	rcu_read_unlock();
627 	__IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
628 	return NULL;
629 }
630 EXPORT_SYMBOL_GPL(inet_csk_route_req);
631 
inet_csk_route_child_sock(const struct sock * sk,struct sock * newsk,const struct request_sock * req)632 struct dst_entry *inet_csk_route_child_sock(const struct sock *sk,
633 					    struct sock *newsk,
634 					    const struct request_sock *req)
635 {
636 	const struct inet_request_sock *ireq = inet_rsk(req);
637 	struct net *net = read_pnet(&ireq->ireq_net);
638 	struct inet_sock *newinet = inet_sk(newsk);
639 	struct ip_options_rcu *opt;
640 	struct flowi4 *fl4;
641 	struct rtable *rt;
642 
643 	opt = rcu_dereference(ireq->ireq_opt);
644 	fl4 = &newinet->cork.fl.u.ip4;
645 
646 	flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
647 			   RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
648 			   sk->sk_protocol, inet_sk_flowi_flags(sk),
649 			   (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
650 			   ireq->ir_loc_addr, ireq->ir_rmt_port,
651 			   htons(ireq->ir_num), sk->sk_uid);
652 	security_req_classify_flow(req, flowi4_to_flowi_common(fl4));
653 	rt = ip_route_output_flow(net, fl4, sk);
654 	if (IS_ERR(rt))
655 		goto no_route;
656 	if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
657 		goto route_err;
658 	return &rt->dst;
659 
660 route_err:
661 	ip_rt_put(rt);
662 no_route:
663 	__IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
664 	return NULL;
665 }
666 EXPORT_SYMBOL_GPL(inet_csk_route_child_sock);
667 
668 /* 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)669 static void syn_ack_recalc(struct request_sock *req,
670 			   const int max_syn_ack_retries,
671 			   const u8 rskq_defer_accept,
672 			   int *expire, int *resend)
673 {
674 	if (!rskq_defer_accept) {
675 		*expire = req->num_timeout >= max_syn_ack_retries;
676 		*resend = 1;
677 		return;
678 	}
679 	*expire = req->num_timeout >= max_syn_ack_retries &&
680 		  (!inet_rsk(req)->acked || req->num_timeout >= rskq_defer_accept);
681 	/* Do not resend while waiting for data after ACK,
682 	 * start to resend on end of deferring period to give
683 	 * last chance for data or ACK to create established socket.
684 	 */
685 	*resend = !inet_rsk(req)->acked ||
686 		  req->num_timeout >= rskq_defer_accept - 1;
687 }
688 
inet_rtx_syn_ack(const struct sock * parent,struct request_sock * req)689 int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req)
690 {
691 	int err = req->rsk_ops->rtx_syn_ack(parent, req);
692 
693 	if (!err)
694 		req->num_retrans++;
695 	return err;
696 }
697 EXPORT_SYMBOL(inet_rtx_syn_ack);
698 
699 /* return true if req was found in the ehash table */
reqsk_queue_unlink(struct request_sock * req)700 static bool reqsk_queue_unlink(struct request_sock *req)
701 {
702 	struct inet_hashinfo *hashinfo = req_to_sk(req)->sk_prot->h.hashinfo;
703 	bool found = false;
704 
705 	if (sk_hashed(req_to_sk(req))) {
706 		spinlock_t *lock = inet_ehash_lockp(hashinfo, req->rsk_hash);
707 
708 		spin_lock(lock);
709 		found = __sk_nulls_del_node_init_rcu(req_to_sk(req));
710 		spin_unlock(lock);
711 	}
712 	if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer))
713 		reqsk_put(req);
714 	return found;
715 }
716 
inet_csk_reqsk_queue_drop(struct sock * sk,struct request_sock * req)717 bool inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req)
718 {
719 	bool unlinked = reqsk_queue_unlink(req);
720 
721 	if (unlinked) {
722 		reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
723 		reqsk_put(req);
724 	}
725 	return unlinked;
726 }
727 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop);
728 
inet_csk_reqsk_queue_drop_and_put(struct sock * sk,struct request_sock * req)729 void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req)
730 {
731 	inet_csk_reqsk_queue_drop(sk, req);
732 	reqsk_put(req);
733 }
734 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop_and_put);
735 
reqsk_timer_handler(struct timer_list * t)736 static void reqsk_timer_handler(struct timer_list *t)
737 {
738 	struct request_sock *req = from_timer(req, t, rsk_timer);
739 	struct sock *sk_listener = req->rsk_listener;
740 	struct net *net = sock_net(sk_listener);
741 	struct inet_connection_sock *icsk = inet_csk(sk_listener);
742 	struct request_sock_queue *queue = &icsk->icsk_accept_queue;
743 	int max_syn_ack_retries, qlen, expire = 0, resend = 0;
744 
745 	if (inet_sk_state_load(sk_listener) != TCP_LISTEN)
746 		goto drop;
747 
748 	max_syn_ack_retries = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_synack_retries;
749 	/* Normally all the openreqs are young and become mature
750 	 * (i.e. converted to established socket) for first timeout.
751 	 * If synack was not acknowledged for 1 second, it means
752 	 * one of the following things: synack was lost, ack was lost,
753 	 * rtt is high or nobody planned to ack (i.e. synflood).
754 	 * When server is a bit loaded, queue is populated with old
755 	 * open requests, reducing effective size of queue.
756 	 * When server is well loaded, queue size reduces to zero
757 	 * after several minutes of work. It is not synflood,
758 	 * it is normal operation. The solution is pruning
759 	 * too old entries overriding normal timeout, when
760 	 * situation becomes dangerous.
761 	 *
762 	 * Essentially, we reserve half of room for young
763 	 * embrions; and abort old ones without pity, if old
764 	 * ones are about to clog our table.
765 	 */
766 	qlen = reqsk_queue_len(queue);
767 	if ((qlen << 1) > max(8U, READ_ONCE(sk_listener->sk_max_ack_backlog))) {
768 		int young = reqsk_queue_len_young(queue) << 1;
769 
770 		while (max_syn_ack_retries > 2) {
771 			if (qlen < young)
772 				break;
773 			max_syn_ack_retries--;
774 			young <<= 1;
775 		}
776 	}
777 	syn_ack_recalc(req, max_syn_ack_retries, READ_ONCE(queue->rskq_defer_accept),
778 		       &expire, &resend);
779 	req->rsk_ops->syn_ack_timeout(req);
780 	if (!expire &&
781 	    (!resend ||
782 	     !inet_rtx_syn_ack(sk_listener, req) ||
783 	     inet_rsk(req)->acked)) {
784 		unsigned long timeo;
785 
786 		if (req->num_timeout++ == 0)
787 			atomic_dec(&queue->young);
788 		timeo = min(TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX);
789 		mod_timer(&req->rsk_timer, jiffies + timeo);
790 		return;
791 	}
792 drop:
793 	inet_csk_reqsk_queue_drop_and_put(sk_listener, req);
794 }
795 
reqsk_queue_hash_req(struct request_sock * req,unsigned long timeout)796 static void reqsk_queue_hash_req(struct request_sock *req,
797 				 unsigned long timeout)
798 {
799 	timer_setup(&req->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
800 	mod_timer(&req->rsk_timer, jiffies + timeout);
801 
802 	inet_ehash_insert(req_to_sk(req), NULL, NULL);
803 	/* before letting lookups find us, make sure all req fields
804 	 * are committed to memory and refcnt initialized.
805 	 */
806 	smp_wmb();
807 	refcount_set(&req->rsk_refcnt, 2 + 1);
808 }
809 
inet_csk_reqsk_queue_hash_add(struct sock * sk,struct request_sock * req,unsigned long timeout)810 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
811 				   unsigned long timeout)
812 {
813 	reqsk_queue_hash_req(req, timeout);
814 	inet_csk_reqsk_queue_added(sk);
815 }
816 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
817 
inet_clone_ulp(const struct request_sock * req,struct sock * newsk,const gfp_t priority)818 static void inet_clone_ulp(const struct request_sock *req, struct sock *newsk,
819 			   const gfp_t priority)
820 {
821 	struct inet_connection_sock *icsk = inet_csk(newsk);
822 
823 	if (!icsk->icsk_ulp_ops)
824 		return;
825 
826 	icsk->icsk_ulp_ops->clone(req, newsk, priority);
827 }
828 
829 /**
830  *	inet_csk_clone_lock - clone an inet socket, and lock its clone
831  *	@sk: the socket to clone
832  *	@req: request_sock
833  *	@priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
834  *
835  *	Caller must unlock socket even in error path (bh_unlock_sock(newsk))
836  */
inet_csk_clone_lock(const struct sock * sk,const struct request_sock * req,const gfp_t priority)837 struct sock *inet_csk_clone_lock(const struct sock *sk,
838 				 const struct request_sock *req,
839 				 const gfp_t priority)
840 {
841 	struct sock *newsk = sk_clone_lock(sk, priority);
842 
843 	if (newsk) {
844 		struct inet_connection_sock *newicsk = inet_csk(newsk);
845 
846 		inet_sk_set_state(newsk, TCP_SYN_RECV);
847 		newicsk->icsk_bind_hash = NULL;
848 
849 		inet_sk(newsk)->inet_dport = inet_rsk(req)->ir_rmt_port;
850 		inet_sk(newsk)->inet_num = inet_rsk(req)->ir_num;
851 		inet_sk(newsk)->inet_sport = htons(inet_rsk(req)->ir_num);
852 
853 		/* listeners have SOCK_RCU_FREE, not the children */
854 		sock_reset_flag(newsk, SOCK_RCU_FREE);
855 
856 		inet_sk(newsk)->mc_list = NULL;
857 
858 		newsk->sk_mark = inet_rsk(req)->ir_mark;
859 		atomic64_set(&newsk->sk_cookie,
860 			     atomic64_read(&inet_rsk(req)->ir_cookie));
861 
862 		newicsk->icsk_retransmits = 0;
863 		newicsk->icsk_backoff	  = 0;
864 		newicsk->icsk_probes_out  = 0;
865 		newicsk->icsk_probes_tstamp = 0;
866 
867 		/* Deinitialize accept_queue to trap illegal accesses. */
868 		memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
869 
870 		inet_clone_ulp(req, newsk, priority);
871 
872 		security_inet_csk_clone(newsk, req);
873 	}
874 	return newsk;
875 }
876 EXPORT_SYMBOL_GPL(inet_csk_clone_lock);
877 
878 /*
879  * At this point, there should be no process reference to this
880  * socket, and thus no user references at all.  Therefore we
881  * can assume the socket waitqueue is inactive and nobody will
882  * try to jump onto it.
883  */
inet_csk_destroy_sock(struct sock * sk)884 void inet_csk_destroy_sock(struct sock *sk)
885 {
886 	WARN_ON(sk->sk_state != TCP_CLOSE);
887 	WARN_ON(!sock_flag(sk, SOCK_DEAD));
888 
889 	/* It cannot be in hash table! */
890 	WARN_ON(!sk_unhashed(sk));
891 
892 	/* If it has not 0 inet_sk(sk)->inet_num, it must be bound */
893 	WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash);
894 
895 	sk->sk_prot->destroy(sk);
896 
897 	sk_stream_kill_queues(sk);
898 
899 	xfrm_sk_free_policy(sk);
900 
901 	sk_refcnt_debug_release(sk);
902 
903 	this_cpu_dec(*sk->sk_prot->orphan_count);
904 
905 	sock_put(sk);
906 }
907 EXPORT_SYMBOL(inet_csk_destroy_sock);
908 
909 /* This function allows to force a closure of a socket after the call to
910  * tcp/dccp_create_openreq_child().
911  */
inet_csk_prepare_forced_close(struct sock * sk)912 void inet_csk_prepare_forced_close(struct sock *sk)
913 	__releases(&sk->sk_lock.slock)
914 {
915 	/* sk_clone_lock locked the socket and set refcnt to 2 */
916 	bh_unlock_sock(sk);
917 	sock_put(sk);
918 	inet_csk_prepare_for_destroy_sock(sk);
919 	inet_sk(sk)->inet_num = 0;
920 }
921 EXPORT_SYMBOL(inet_csk_prepare_forced_close);
922 
inet_ulp_can_listen(const struct sock * sk)923 static int inet_ulp_can_listen(const struct sock *sk)
924 {
925 	const struct inet_connection_sock *icsk = inet_csk(sk);
926 
927 	if (icsk->icsk_ulp_ops && !icsk->icsk_ulp_ops->clone)
928 		return -EINVAL;
929 
930 	return 0;
931 }
932 
inet_csk_listen_start(struct sock * sk,int backlog)933 int inet_csk_listen_start(struct sock *sk, int backlog)
934 {
935 	struct inet_connection_sock *icsk = inet_csk(sk);
936 	struct inet_sock *inet = inet_sk(sk);
937 	int err;
938 
939 	err = inet_ulp_can_listen(sk);
940 	if (unlikely(err))
941 		return err;
942 
943 	reqsk_queue_alloc(&icsk->icsk_accept_queue);
944 
945 	sk->sk_ack_backlog = 0;
946 	inet_csk_delack_init(sk);
947 
948 	/* There is race window here: we announce ourselves listening,
949 	 * but this transition is still not validated by get_port().
950 	 * It is OK, because this socket enters to hash table only
951 	 * after validation is complete.
952 	 */
953 	err = -EADDRINUSE;
954 	inet_sk_state_store(sk, TCP_LISTEN);
955 	if (!sk->sk_prot->get_port(sk, inet->inet_num)) {
956 		inet->inet_sport = htons(inet->inet_num);
957 
958 		sk_dst_reset(sk);
959 		err = sk->sk_prot->hash(sk);
960 
961 		if (likely(!err))
962 			return 0;
963 	}
964 
965 	inet_sk_set_state(sk, TCP_CLOSE);
966 	return err;
967 }
968 EXPORT_SYMBOL_GPL(inet_csk_listen_start);
969 
inet_child_forget(struct sock * sk,struct request_sock * req,struct sock * child)970 static void inet_child_forget(struct sock *sk, struct request_sock *req,
971 			      struct sock *child)
972 {
973 	sk->sk_prot->disconnect(child, O_NONBLOCK);
974 
975 	sock_orphan(child);
976 
977 	this_cpu_inc(*sk->sk_prot->orphan_count);
978 
979 	if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->tfo_listener) {
980 		BUG_ON(rcu_access_pointer(tcp_sk(child)->fastopen_rsk) != req);
981 		BUG_ON(sk != req->rsk_listener);
982 
983 		/* Paranoid, to prevent race condition if
984 		 * an inbound pkt destined for child is
985 		 * blocked by sock lock in tcp_v4_rcv().
986 		 * Also to satisfy an assertion in
987 		 * tcp_v4_destroy_sock().
988 		 */
989 		RCU_INIT_POINTER(tcp_sk(child)->fastopen_rsk, NULL);
990 	}
991 	inet_csk_destroy_sock(child);
992 }
993 
inet_csk_reqsk_queue_add(struct sock * sk,struct request_sock * req,struct sock * child)994 struct sock *inet_csk_reqsk_queue_add(struct sock *sk,
995 				      struct request_sock *req,
996 				      struct sock *child)
997 {
998 	struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
999 
1000 	spin_lock(&queue->rskq_lock);
1001 	if (unlikely(sk->sk_state != TCP_LISTEN)) {
1002 		inet_child_forget(sk, req, child);
1003 		child = NULL;
1004 	} else {
1005 		req->sk = child;
1006 		req->dl_next = NULL;
1007 		if (queue->rskq_accept_head == NULL)
1008 			WRITE_ONCE(queue->rskq_accept_head, req);
1009 		else
1010 			queue->rskq_accept_tail->dl_next = req;
1011 		queue->rskq_accept_tail = req;
1012 		sk_acceptq_added(sk);
1013 	}
1014 	spin_unlock(&queue->rskq_lock);
1015 	return child;
1016 }
1017 EXPORT_SYMBOL(inet_csk_reqsk_queue_add);
1018 
inet_csk_complete_hashdance(struct sock * sk,struct sock * child,struct request_sock * req,bool own_req)1019 struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child,
1020 					 struct request_sock *req, bool own_req)
1021 {
1022 	if (own_req) {
1023 		inet_csk_reqsk_queue_drop(sk, req);
1024 		reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
1025 		if (inet_csk_reqsk_queue_add(sk, req, child))
1026 			return child;
1027 	}
1028 	/* Too bad, another child took ownership of the request, undo. */
1029 	bh_unlock_sock(child);
1030 	sock_put(child);
1031 	return NULL;
1032 }
1033 EXPORT_SYMBOL(inet_csk_complete_hashdance);
1034 
1035 /*
1036  *	This routine closes sockets which have been at least partially
1037  *	opened, but not yet accepted.
1038  */
inet_csk_listen_stop(struct sock * sk)1039 void inet_csk_listen_stop(struct sock *sk)
1040 {
1041 	struct inet_connection_sock *icsk = inet_csk(sk);
1042 	struct request_sock_queue *queue = &icsk->icsk_accept_queue;
1043 	struct request_sock *next, *req;
1044 
1045 	/* Following specs, it would be better either to send FIN
1046 	 * (and enter FIN-WAIT-1, it is normal close)
1047 	 * or to send active reset (abort).
1048 	 * Certainly, it is pretty dangerous while synflood, but it is
1049 	 * bad justification for our negligence 8)
1050 	 * To be honest, we are not able to make either
1051 	 * of the variants now.			--ANK
1052 	 */
1053 	while ((req = reqsk_queue_remove(queue, sk)) != NULL) {
1054 		struct sock *child = req->sk;
1055 
1056 		local_bh_disable();
1057 		bh_lock_sock(child);
1058 		WARN_ON(sock_owned_by_user(child));
1059 		sock_hold(child);
1060 
1061 		inet_child_forget(sk, req, child);
1062 		reqsk_put(req);
1063 		bh_unlock_sock(child);
1064 		local_bh_enable();
1065 		sock_put(child);
1066 
1067 		cond_resched();
1068 	}
1069 	if (queue->fastopenq.rskq_rst_head) {
1070 		/* Free all the reqs queued in rskq_rst_head. */
1071 		spin_lock_bh(&queue->fastopenq.lock);
1072 		req = queue->fastopenq.rskq_rst_head;
1073 		queue->fastopenq.rskq_rst_head = NULL;
1074 		spin_unlock_bh(&queue->fastopenq.lock);
1075 		while (req != NULL) {
1076 			next = req->dl_next;
1077 			reqsk_put(req);
1078 			req = next;
1079 		}
1080 	}
1081 	WARN_ON_ONCE(sk->sk_ack_backlog);
1082 }
1083 EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
1084 
inet_csk_addr2sockaddr(struct sock * sk,struct sockaddr * uaddr)1085 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
1086 {
1087 	struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
1088 	const struct inet_sock *inet = inet_sk(sk);
1089 
1090 	sin->sin_family		= AF_INET;
1091 	sin->sin_addr.s_addr	= inet->inet_daddr;
1092 	sin->sin_port		= inet->inet_dport;
1093 }
1094 EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);
1095 
inet_csk_rebuild_route(struct sock * sk,struct flowi * fl)1096 static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *fl)
1097 {
1098 	const struct inet_sock *inet = inet_sk(sk);
1099 	const struct ip_options_rcu *inet_opt;
1100 	__be32 daddr = inet->inet_daddr;
1101 	struct flowi4 *fl4;
1102 	struct rtable *rt;
1103 
1104 	rcu_read_lock();
1105 	inet_opt = rcu_dereference(inet->inet_opt);
1106 	if (inet_opt && inet_opt->opt.srr)
1107 		daddr = inet_opt->opt.faddr;
1108 	fl4 = &fl->u.ip4;
1109 	rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr,
1110 				   inet->inet_saddr, inet->inet_dport,
1111 				   inet->inet_sport, sk->sk_protocol,
1112 				   RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
1113 	if (IS_ERR(rt))
1114 		rt = NULL;
1115 	if (rt)
1116 		sk_setup_caps(sk, &rt->dst);
1117 	rcu_read_unlock();
1118 
1119 	return &rt->dst;
1120 }
1121 
inet_csk_update_pmtu(struct sock * sk,u32 mtu)1122 struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu)
1123 {
1124 	struct dst_entry *dst = __sk_dst_check(sk, 0);
1125 	struct inet_sock *inet = inet_sk(sk);
1126 
1127 	if (!dst) {
1128 		dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1129 		if (!dst)
1130 			goto out;
1131 	}
1132 	dst->ops->update_pmtu(dst, sk, NULL, mtu, true);
1133 
1134 	dst = __sk_dst_check(sk, 0);
1135 	if (!dst)
1136 		dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1137 out:
1138 	return dst;
1139 }
1140 EXPORT_SYMBOL_GPL(inet_csk_update_pmtu);
1141