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  */
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  */
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 
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 	return ipv4_rcv_saddr_equal(sk->sk_rcv_saddr, sk2->sk_rcv_saddr,
106 				    ipv6_only_sock(sk2), match_wildcard,
107 				    match_wildcard);
108 }
109 EXPORT_SYMBOL(inet_rcv_saddr_equal);
110 
111 bool inet_rcv_saddr_any(const struct sock *sk)
112 {
113 #if IS_ENABLED(CONFIG_IPV6)
114 	if (sk->sk_family == AF_INET6)
115 		return ipv6_addr_any(&sk->sk_v6_rcv_saddr);
116 #endif
117 	return !sk->sk_rcv_saddr;
118 }
119 
120 void inet_get_local_port_range(struct net *net, int *low, int *high)
121 {
122 	unsigned int seq;
123 
124 	do {
125 		seq = read_seqbegin(&net->ipv4.ip_local_ports.lock);
126 
127 		*low = net->ipv4.ip_local_ports.range[0];
128 		*high = net->ipv4.ip_local_ports.range[1];
129 	} while (read_seqretry(&net->ipv4.ip_local_ports.lock, seq));
130 }
131 EXPORT_SYMBOL(inet_get_local_port_range);
132 
133 static int inet_csk_bind_conflict(const struct sock *sk,
134 				  const struct inet_bind_bucket *tb,
135 				  bool relax, bool reuseport_ok)
136 {
137 	struct sock *sk2;
138 	bool reuseport_cb_ok;
139 	bool reuse = sk->sk_reuse;
140 	bool reuseport = !!sk->sk_reuseport;
141 	struct sock_reuseport *reuseport_cb;
142 	kuid_t uid = sock_i_uid((struct sock *)sk);
143 
144 	rcu_read_lock();
145 	reuseport_cb = rcu_dereference(sk->sk_reuseport_cb);
146 	/* paired with WRITE_ONCE() in __reuseport_(add|detach)_closed_sock */
147 	reuseport_cb_ok = !reuseport_cb || READ_ONCE(reuseport_cb->num_closed_socks);
148 	rcu_read_unlock();
149 
150 	/*
151 	 * Unlike other sk lookup places we do not check
152 	 * for sk_net here, since _all_ the socks listed
153 	 * in tb->owners list belong to the same net - the
154 	 * one this bucket belongs to.
155 	 */
156 
157 	sk_for_each_bound(sk2, &tb->owners) {
158 		if (sk != sk2 &&
159 		    (!sk->sk_bound_dev_if ||
160 		     !sk2->sk_bound_dev_if ||
161 		     sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
162 			if (reuse && sk2->sk_reuse &&
163 			    sk2->sk_state != TCP_LISTEN) {
164 				if ((!relax ||
165 				     (!reuseport_ok &&
166 				      reuseport && sk2->sk_reuseport &&
167 				      reuseport_cb_ok &&
168 				      (sk2->sk_state == TCP_TIME_WAIT ||
169 				       uid_eq(uid, sock_i_uid(sk2))))) &&
170 				    inet_rcv_saddr_equal(sk, sk2, true))
171 					break;
172 			} else if (!reuseport_ok ||
173 				   !reuseport || !sk2->sk_reuseport ||
174 				   !reuseport_cb_ok ||
175 				   (sk2->sk_state != TCP_TIME_WAIT &&
176 				    !uid_eq(uid, sock_i_uid(sk2)))) {
177 				if (inet_rcv_saddr_equal(sk, sk2, true))
178 					break;
179 			}
180 		}
181 	}
182 	return sk2 != NULL;
183 }
184 
185 /*
186  * Find an open port number for the socket.  Returns with the
187  * inet_bind_hashbucket lock held.
188  */
189 static struct inet_bind_hashbucket *
190 inet_csk_find_open_port(struct sock *sk, struct inet_bind_bucket **tb_ret, int *port_ret)
191 {
192 	struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
193 	int port = 0;
194 	struct inet_bind_hashbucket *head;
195 	struct net *net = sock_net(sk);
196 	bool relax = false;
197 	int i, low, high, attempt_half;
198 	struct inet_bind_bucket *tb;
199 	u32 remaining, offset;
200 	int l3mdev;
201 
202 	l3mdev = inet_sk_bound_l3mdev(sk);
203 ports_exhausted:
204 	attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0;
205 other_half_scan:
206 	inet_get_local_port_range(net, &low, &high);
207 	high++; /* [32768, 60999] -> [32768, 61000[ */
208 	if (high - low < 4)
209 		attempt_half = 0;
210 	if (attempt_half) {
211 		int half = low + (((high - low) >> 2) << 1);
212 
213 		if (attempt_half == 1)
214 			high = half;
215 		else
216 			low = half;
217 	}
218 	remaining = high - low;
219 	if (likely(remaining > 1))
220 		remaining &= ~1U;
221 
222 	offset = prandom_u32() % remaining;
223 	/* __inet_hash_connect() favors ports having @low parity
224 	 * We do the opposite to not pollute connect() users.
225 	 */
226 	offset |= 1U;
227 
228 other_parity_scan:
229 	port = low + offset;
230 	for (i = 0; i < remaining; i += 2, port += 2) {
231 		if (unlikely(port >= high))
232 			port -= remaining;
233 		if (inet_is_local_reserved_port(net, port))
234 			continue;
235 		head = &hinfo->bhash[inet_bhashfn(net, port,
236 						  hinfo->bhash_size)];
237 		spin_lock_bh(&head->lock);
238 		inet_bind_bucket_for_each(tb, &head->chain)
239 			if (net_eq(ib_net(tb), net) && tb->l3mdev == l3mdev &&
240 			    tb->port == port) {
241 				if (!inet_csk_bind_conflict(sk, tb, relax, false))
242 					goto success;
243 				goto next_port;
244 			}
245 		tb = NULL;
246 		goto success;
247 next_port:
248 		spin_unlock_bh(&head->lock);
249 		cond_resched();
250 	}
251 
252 	offset--;
253 	if (!(offset & 1))
254 		goto other_parity_scan;
255 
256 	if (attempt_half == 1) {
257 		/* OK we now try the upper half of the range */
258 		attempt_half = 2;
259 		goto other_half_scan;
260 	}
261 
262 	if (net->ipv4.sysctl_ip_autobind_reuse && !relax) {
263 		/* We still have a chance to connect to different destinations */
264 		relax = true;
265 		goto ports_exhausted;
266 	}
267 	return NULL;
268 success:
269 	*port_ret = port;
270 	*tb_ret = tb;
271 	return head;
272 }
273 
274 static inline int sk_reuseport_match(struct inet_bind_bucket *tb,
275 				     struct sock *sk)
276 {
277 	kuid_t uid = sock_i_uid(sk);
278 
279 	if (tb->fastreuseport <= 0)
280 		return 0;
281 	if (!sk->sk_reuseport)
282 		return 0;
283 	if (rcu_access_pointer(sk->sk_reuseport_cb))
284 		return 0;
285 	if (!uid_eq(tb->fastuid, uid))
286 		return 0;
287 	/* We only need to check the rcv_saddr if this tb was once marked
288 	 * without fastreuseport and then was reset, as we can only know that
289 	 * the fast_*rcv_saddr doesn't have any conflicts with the socks on the
290 	 * owners list.
291 	 */
292 	if (tb->fastreuseport == FASTREUSEPORT_ANY)
293 		return 1;
294 #if IS_ENABLED(CONFIG_IPV6)
295 	if (tb->fast_sk_family == AF_INET6)
296 		return ipv6_rcv_saddr_equal(&tb->fast_v6_rcv_saddr,
297 					    inet6_rcv_saddr(sk),
298 					    tb->fast_rcv_saddr,
299 					    sk->sk_rcv_saddr,
300 					    tb->fast_ipv6_only,
301 					    ipv6_only_sock(sk), true, false);
302 #endif
303 	return ipv4_rcv_saddr_equal(tb->fast_rcv_saddr, sk->sk_rcv_saddr,
304 				    ipv6_only_sock(sk), true, false);
305 }
306 
307 void inet_csk_update_fastreuse(struct inet_bind_bucket *tb,
308 			       struct sock *sk)
309 {
310 	kuid_t uid = sock_i_uid(sk);
311 	bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
312 
313 	if (hlist_empty(&tb->owners)) {
314 		tb->fastreuse = reuse;
315 		if (sk->sk_reuseport) {
316 			tb->fastreuseport = FASTREUSEPORT_ANY;
317 			tb->fastuid = uid;
318 			tb->fast_rcv_saddr = sk->sk_rcv_saddr;
319 			tb->fast_ipv6_only = ipv6_only_sock(sk);
320 			tb->fast_sk_family = sk->sk_family;
321 #if IS_ENABLED(CONFIG_IPV6)
322 			tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
323 #endif
324 		} else {
325 			tb->fastreuseport = 0;
326 		}
327 	} else {
328 		if (!reuse)
329 			tb->fastreuse = 0;
330 		if (sk->sk_reuseport) {
331 			/* We didn't match or we don't have fastreuseport set on
332 			 * the tb, but we have sk_reuseport set on this socket
333 			 * and we know that there are no bind conflicts with
334 			 * this socket in this tb, so reset our tb's reuseport
335 			 * settings so that any subsequent sockets that match
336 			 * our current socket will be put on the fast path.
337 			 *
338 			 * If we reset we need to set FASTREUSEPORT_STRICT so we
339 			 * do extra checking for all subsequent sk_reuseport
340 			 * socks.
341 			 */
342 			if (!sk_reuseport_match(tb, sk)) {
343 				tb->fastreuseport = FASTREUSEPORT_STRICT;
344 				tb->fastuid = uid;
345 				tb->fast_rcv_saddr = sk->sk_rcv_saddr;
346 				tb->fast_ipv6_only = ipv6_only_sock(sk);
347 				tb->fast_sk_family = sk->sk_family;
348 #if IS_ENABLED(CONFIG_IPV6)
349 				tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
350 #endif
351 			}
352 		} else {
353 			tb->fastreuseport = 0;
354 		}
355 	}
356 }
357 
358 /* Obtain a reference to a local port for the given sock,
359  * if snum is zero it means select any available local port.
360  * We try to allocate an odd port (and leave even ports for connect())
361  */
362 int inet_csk_get_port(struct sock *sk, unsigned short snum)
363 {
364 	bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
365 	struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
366 	int ret = 1, port = snum;
367 	struct inet_bind_hashbucket *head;
368 	struct net *net = sock_net(sk);
369 	struct inet_bind_bucket *tb = NULL;
370 	int l3mdev;
371 
372 	l3mdev = inet_sk_bound_l3mdev(sk);
373 
374 	if (!port) {
375 		head = inet_csk_find_open_port(sk, &tb, &port);
376 		if (!head)
377 			return ret;
378 		if (!tb)
379 			goto tb_not_found;
380 		goto success;
381 	}
382 	head = &hinfo->bhash[inet_bhashfn(net, port,
383 					  hinfo->bhash_size)];
384 	spin_lock_bh(&head->lock);
385 	inet_bind_bucket_for_each(tb, &head->chain)
386 		if (net_eq(ib_net(tb), net) && tb->l3mdev == l3mdev &&
387 		    tb->port == port)
388 			goto tb_found;
389 tb_not_found:
390 	tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
391 				     net, head, port, l3mdev);
392 	if (!tb)
393 		goto fail_unlock;
394 tb_found:
395 	if (!hlist_empty(&tb->owners)) {
396 		if (sk->sk_reuse == SK_FORCE_REUSE)
397 			goto success;
398 
399 		if ((tb->fastreuse > 0 && reuse) ||
400 		    sk_reuseport_match(tb, sk))
401 			goto success;
402 		if (inet_csk_bind_conflict(sk, tb, true, true))
403 			goto fail_unlock;
404 	}
405 success:
406 	inet_csk_update_fastreuse(tb, sk);
407 
408 	if (!inet_csk(sk)->icsk_bind_hash)
409 		inet_bind_hash(sk, tb, port);
410 	WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);
411 	ret = 0;
412 
413 fail_unlock:
414 	spin_unlock_bh(&head->lock);
415 	return ret;
416 }
417 EXPORT_SYMBOL_GPL(inet_csk_get_port);
418 
419 /*
420  * Wait for an incoming connection, avoid race conditions. This must be called
421  * with the socket locked.
422  */
423 static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
424 {
425 	struct inet_connection_sock *icsk = inet_csk(sk);
426 	DEFINE_WAIT(wait);
427 	int err;
428 
429 	/*
430 	 * True wake-one mechanism for incoming connections: only
431 	 * one process gets woken up, not the 'whole herd'.
432 	 * Since we do not 'race & poll' for established sockets
433 	 * anymore, the common case will execute the loop only once.
434 	 *
435 	 * Subtle issue: "add_wait_queue_exclusive()" will be added
436 	 * after any current non-exclusive waiters, and we know that
437 	 * it will always _stay_ after any new non-exclusive waiters
438 	 * because all non-exclusive waiters are added at the
439 	 * beginning of the wait-queue. As such, it's ok to "drop"
440 	 * our exclusiveness temporarily when we get woken up without
441 	 * having to remove and re-insert us on the wait queue.
442 	 */
443 	for (;;) {
444 		prepare_to_wait_exclusive(sk_sleep(sk), &wait,
445 					  TASK_INTERRUPTIBLE);
446 		release_sock(sk);
447 		if (reqsk_queue_empty(&icsk->icsk_accept_queue))
448 			timeo = schedule_timeout(timeo);
449 		sched_annotate_sleep();
450 		lock_sock(sk);
451 		err = 0;
452 		if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
453 			break;
454 		err = -EINVAL;
455 		if (sk->sk_state != TCP_LISTEN)
456 			break;
457 		err = sock_intr_errno(timeo);
458 		if (signal_pending(current))
459 			break;
460 		err = -EAGAIN;
461 		if (!timeo)
462 			break;
463 	}
464 	finish_wait(sk_sleep(sk), &wait);
465 	return err;
466 }
467 
468 /*
469  * This will accept the next outstanding connection.
470  */
471 struct sock *inet_csk_accept(struct sock *sk, int flags, int *err, bool kern)
472 {
473 	struct inet_connection_sock *icsk = inet_csk(sk);
474 	struct request_sock_queue *queue = &icsk->icsk_accept_queue;
475 	struct request_sock *req;
476 	struct sock *newsk;
477 	int error;
478 
479 	lock_sock(sk);
480 
481 	/* We need to make sure that this socket is listening,
482 	 * and that it has something pending.
483 	 */
484 	error = -EINVAL;
485 	if (sk->sk_state != TCP_LISTEN)
486 		goto out_err;
487 
488 	/* Find already established connection */
489 	if (reqsk_queue_empty(queue)) {
490 		long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
491 
492 		/* If this is a non blocking socket don't sleep */
493 		error = -EAGAIN;
494 		if (!timeo)
495 			goto out_err;
496 
497 		error = inet_csk_wait_for_connect(sk, timeo);
498 		if (error)
499 			goto out_err;
500 	}
501 	req = reqsk_queue_remove(queue, sk);
502 	newsk = req->sk;
503 
504 	if (sk->sk_protocol == IPPROTO_TCP &&
505 	    tcp_rsk(req)->tfo_listener) {
506 		spin_lock_bh(&queue->fastopenq.lock);
507 		if (tcp_rsk(req)->tfo_listener) {
508 			/* We are still waiting for the final ACK from 3WHS
509 			 * so can't free req now. Instead, we set req->sk to
510 			 * NULL to signify that the child socket is taken
511 			 * so reqsk_fastopen_remove() will free the req
512 			 * when 3WHS finishes (or is aborted).
513 			 */
514 			req->sk = NULL;
515 			req = NULL;
516 		}
517 		spin_unlock_bh(&queue->fastopenq.lock);
518 	}
519 
520 out:
521 	release_sock(sk);
522 	if (newsk && mem_cgroup_sockets_enabled) {
523 		int amt;
524 
525 		/* atomically get the memory usage, set and charge the
526 		 * newsk->sk_memcg.
527 		 */
528 		lock_sock(newsk);
529 
530 		/* The socket has not been accepted yet, no need to look at
531 		 * newsk->sk_wmem_queued.
532 		 */
533 		amt = sk_mem_pages(newsk->sk_forward_alloc +
534 				   atomic_read(&newsk->sk_rmem_alloc));
535 		mem_cgroup_sk_alloc(newsk);
536 		if (newsk->sk_memcg && amt)
537 			mem_cgroup_charge_skmem(newsk->sk_memcg, amt,
538 						GFP_KERNEL | __GFP_NOFAIL);
539 
540 		release_sock(newsk);
541 	}
542 	if (req)
543 		reqsk_put(req);
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  */
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 
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 
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 
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 
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 
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 */
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 
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 static struct request_sock *inet_reqsk_clone(struct request_sock *req,
700 					     struct sock *sk)
701 {
702 	struct sock *req_sk, *nreq_sk;
703 	struct request_sock *nreq;
704 
705 	nreq = kmem_cache_alloc(req->rsk_ops->slab, GFP_ATOMIC | __GFP_NOWARN);
706 	if (!nreq) {
707 		__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);
708 
709 		/* paired with refcount_inc_not_zero() in reuseport_migrate_sock() */
710 		sock_put(sk);
711 		return NULL;
712 	}
713 
714 	req_sk = req_to_sk(req);
715 	nreq_sk = req_to_sk(nreq);
716 
717 	memcpy(nreq_sk, req_sk,
718 	       offsetof(struct sock, sk_dontcopy_begin));
719 	memcpy(&nreq_sk->sk_dontcopy_end, &req_sk->sk_dontcopy_end,
720 	       req->rsk_ops->obj_size - offsetof(struct sock, sk_dontcopy_end));
721 
722 	sk_node_init(&nreq_sk->sk_node);
723 	nreq_sk->sk_tx_queue_mapping = req_sk->sk_tx_queue_mapping;
724 #ifdef CONFIG_XPS
725 	nreq_sk->sk_rx_queue_mapping = req_sk->sk_rx_queue_mapping;
726 #endif
727 	nreq_sk->sk_incoming_cpu = req_sk->sk_incoming_cpu;
728 
729 	nreq->rsk_listener = sk;
730 
731 	/* We need not acquire fastopenq->lock
732 	 * because the child socket is locked in inet_csk_listen_stop().
733 	 */
734 	if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(nreq)->tfo_listener)
735 		rcu_assign_pointer(tcp_sk(nreq->sk)->fastopen_rsk, nreq);
736 
737 	return nreq;
738 }
739 
740 static void reqsk_queue_migrated(struct request_sock_queue *queue,
741 				 const struct request_sock *req)
742 {
743 	if (req->num_timeout == 0)
744 		atomic_inc(&queue->young);
745 	atomic_inc(&queue->qlen);
746 }
747 
748 static void reqsk_migrate_reset(struct request_sock *req)
749 {
750 	req->saved_syn = NULL;
751 #if IS_ENABLED(CONFIG_IPV6)
752 	inet_rsk(req)->ipv6_opt = NULL;
753 	inet_rsk(req)->pktopts = NULL;
754 #else
755 	inet_rsk(req)->ireq_opt = NULL;
756 #endif
757 }
758 
759 /* return true if req was found in the ehash table */
760 static bool reqsk_queue_unlink(struct request_sock *req)
761 {
762 	struct inet_hashinfo *hashinfo = req_to_sk(req)->sk_prot->h.hashinfo;
763 	bool found = false;
764 
765 	if (sk_hashed(req_to_sk(req))) {
766 		spinlock_t *lock = inet_ehash_lockp(hashinfo, req->rsk_hash);
767 
768 		spin_lock(lock);
769 		found = __sk_nulls_del_node_init_rcu(req_to_sk(req));
770 		spin_unlock(lock);
771 	}
772 	if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer))
773 		reqsk_put(req);
774 	return found;
775 }
776 
777 bool inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req)
778 {
779 	bool unlinked = reqsk_queue_unlink(req);
780 
781 	if (unlinked) {
782 		reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
783 		reqsk_put(req);
784 	}
785 	return unlinked;
786 }
787 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop);
788 
789 void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req)
790 {
791 	inet_csk_reqsk_queue_drop(sk, req);
792 	reqsk_put(req);
793 }
794 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop_and_put);
795 
796 static void reqsk_timer_handler(struct timer_list *t)
797 {
798 	struct request_sock *req = from_timer(req, t, rsk_timer);
799 	struct request_sock *nreq = NULL, *oreq = req;
800 	struct sock *sk_listener = req->rsk_listener;
801 	struct inet_connection_sock *icsk;
802 	struct request_sock_queue *queue;
803 	struct net *net;
804 	int max_syn_ack_retries, qlen, expire = 0, resend = 0;
805 
806 	if (inet_sk_state_load(sk_listener) != TCP_LISTEN) {
807 		struct sock *nsk;
808 
809 		nsk = reuseport_migrate_sock(sk_listener, req_to_sk(req), NULL);
810 		if (!nsk)
811 			goto drop;
812 
813 		nreq = inet_reqsk_clone(req, nsk);
814 		if (!nreq)
815 			goto drop;
816 
817 		/* The new timer for the cloned req can decrease the 2
818 		 * by calling inet_csk_reqsk_queue_drop_and_put(), so
819 		 * hold another count to prevent use-after-free and
820 		 * call reqsk_put() just before return.
821 		 */
822 		refcount_set(&nreq->rsk_refcnt, 2 + 1);
823 		timer_setup(&nreq->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
824 		reqsk_queue_migrated(&inet_csk(nsk)->icsk_accept_queue, req);
825 
826 		req = nreq;
827 		sk_listener = nsk;
828 	}
829 
830 	icsk = inet_csk(sk_listener);
831 	net = sock_net(sk_listener);
832 	max_syn_ack_retries = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_synack_retries;
833 	/* Normally all the openreqs are young and become mature
834 	 * (i.e. converted to established socket) for first timeout.
835 	 * If synack was not acknowledged for 1 second, it means
836 	 * one of the following things: synack was lost, ack was lost,
837 	 * rtt is high or nobody planned to ack (i.e. synflood).
838 	 * When server is a bit loaded, queue is populated with old
839 	 * open requests, reducing effective size of queue.
840 	 * When server is well loaded, queue size reduces to zero
841 	 * after several minutes of work. It is not synflood,
842 	 * it is normal operation. The solution is pruning
843 	 * too old entries overriding normal timeout, when
844 	 * situation becomes dangerous.
845 	 *
846 	 * Essentially, we reserve half of room for young
847 	 * embrions; and abort old ones without pity, if old
848 	 * ones are about to clog our table.
849 	 */
850 	queue = &icsk->icsk_accept_queue;
851 	qlen = reqsk_queue_len(queue);
852 	if ((qlen << 1) > max(8U, READ_ONCE(sk_listener->sk_max_ack_backlog))) {
853 		int young = reqsk_queue_len_young(queue) << 1;
854 
855 		while (max_syn_ack_retries > 2) {
856 			if (qlen < young)
857 				break;
858 			max_syn_ack_retries--;
859 			young <<= 1;
860 		}
861 	}
862 	syn_ack_recalc(req, max_syn_ack_retries, READ_ONCE(queue->rskq_defer_accept),
863 		       &expire, &resend);
864 	req->rsk_ops->syn_ack_timeout(req);
865 	if (!expire &&
866 	    (!resend ||
867 	     !inet_rtx_syn_ack(sk_listener, req) ||
868 	     inet_rsk(req)->acked)) {
869 		unsigned long timeo;
870 
871 		if (req->num_timeout++ == 0)
872 			atomic_dec(&queue->young);
873 		timeo = min(TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX);
874 		mod_timer(&req->rsk_timer, jiffies + timeo);
875 
876 		if (!nreq)
877 			return;
878 
879 		if (!inet_ehash_insert(req_to_sk(nreq), req_to_sk(oreq), NULL)) {
880 			/* delete timer */
881 			inet_csk_reqsk_queue_drop(sk_listener, nreq);
882 			goto no_ownership;
883 		}
884 
885 		__NET_INC_STATS(net, LINUX_MIB_TCPMIGRATEREQSUCCESS);
886 		reqsk_migrate_reset(oreq);
887 		reqsk_queue_removed(&inet_csk(oreq->rsk_listener)->icsk_accept_queue, oreq);
888 		reqsk_put(oreq);
889 
890 		reqsk_put(nreq);
891 		return;
892 	}
893 
894 	/* Even if we can clone the req, we may need not retransmit any more
895 	 * SYN+ACKs (nreq->num_timeout > max_syn_ack_retries, etc), or another
896 	 * CPU may win the "own_req" race so that inet_ehash_insert() fails.
897 	 */
898 	if (nreq) {
899 		__NET_INC_STATS(net, LINUX_MIB_TCPMIGRATEREQFAILURE);
900 no_ownership:
901 		reqsk_migrate_reset(nreq);
902 		reqsk_queue_removed(queue, nreq);
903 		__reqsk_free(nreq);
904 	}
905 
906 drop:
907 	inet_csk_reqsk_queue_drop_and_put(oreq->rsk_listener, oreq);
908 }
909 
910 static void reqsk_queue_hash_req(struct request_sock *req,
911 				 unsigned long timeout)
912 {
913 	timer_setup(&req->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
914 	mod_timer(&req->rsk_timer, jiffies + timeout);
915 
916 	inet_ehash_insert(req_to_sk(req), NULL, NULL);
917 	/* before letting lookups find us, make sure all req fields
918 	 * are committed to memory and refcnt initialized.
919 	 */
920 	smp_wmb();
921 	refcount_set(&req->rsk_refcnt, 2 + 1);
922 }
923 
924 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
925 				   unsigned long timeout)
926 {
927 	reqsk_queue_hash_req(req, timeout);
928 	inet_csk_reqsk_queue_added(sk);
929 }
930 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
931 
932 static void inet_clone_ulp(const struct request_sock *req, struct sock *newsk,
933 			   const gfp_t priority)
934 {
935 	struct inet_connection_sock *icsk = inet_csk(newsk);
936 
937 	if (!icsk->icsk_ulp_ops)
938 		return;
939 
940 	if (icsk->icsk_ulp_ops->clone)
941 		icsk->icsk_ulp_ops->clone(req, newsk, priority);
942 }
943 
944 /**
945  *	inet_csk_clone_lock - clone an inet socket, and lock its clone
946  *	@sk: the socket to clone
947  *	@req: request_sock
948  *	@priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
949  *
950  *	Caller must unlock socket even in error path (bh_unlock_sock(newsk))
951  */
952 struct sock *inet_csk_clone_lock(const struct sock *sk,
953 				 const struct request_sock *req,
954 				 const gfp_t priority)
955 {
956 	struct sock *newsk = sk_clone_lock(sk, priority);
957 
958 	if (newsk) {
959 		struct inet_connection_sock *newicsk = inet_csk(newsk);
960 
961 		inet_sk_set_state(newsk, TCP_SYN_RECV);
962 		newicsk->icsk_bind_hash = NULL;
963 
964 		inet_sk(newsk)->inet_dport = inet_rsk(req)->ir_rmt_port;
965 		inet_sk(newsk)->inet_num = inet_rsk(req)->ir_num;
966 		inet_sk(newsk)->inet_sport = htons(inet_rsk(req)->ir_num);
967 
968 		/* listeners have SOCK_RCU_FREE, not the children */
969 		sock_reset_flag(newsk, SOCK_RCU_FREE);
970 
971 		inet_sk(newsk)->mc_list = NULL;
972 
973 		newsk->sk_mark = inet_rsk(req)->ir_mark;
974 		atomic64_set(&newsk->sk_cookie,
975 			     atomic64_read(&inet_rsk(req)->ir_cookie));
976 
977 		newicsk->icsk_retransmits = 0;
978 		newicsk->icsk_backoff	  = 0;
979 		newicsk->icsk_probes_out  = 0;
980 		newicsk->icsk_probes_tstamp = 0;
981 
982 		/* Deinitialize accept_queue to trap illegal accesses. */
983 		memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
984 
985 		inet_clone_ulp(req, newsk, priority);
986 
987 		security_inet_csk_clone(newsk, req);
988 	}
989 	return newsk;
990 }
991 EXPORT_SYMBOL_GPL(inet_csk_clone_lock);
992 
993 /*
994  * At this point, there should be no process reference to this
995  * socket, and thus no user references at all.  Therefore we
996  * can assume the socket waitqueue is inactive and nobody will
997  * try to jump onto it.
998  */
999 void inet_csk_destroy_sock(struct sock *sk)
1000 {
1001 	WARN_ON(sk->sk_state != TCP_CLOSE);
1002 	WARN_ON(!sock_flag(sk, SOCK_DEAD));
1003 
1004 	/* It cannot be in hash table! */
1005 	WARN_ON(!sk_unhashed(sk));
1006 
1007 	/* If it has not 0 inet_sk(sk)->inet_num, it must be bound */
1008 	WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash);
1009 
1010 	sk->sk_prot->destroy(sk);
1011 
1012 	sk_stream_kill_queues(sk);
1013 
1014 	xfrm_sk_free_policy(sk);
1015 
1016 	sk_refcnt_debug_release(sk);
1017 
1018 	this_cpu_dec(*sk->sk_prot->orphan_count);
1019 
1020 	sock_put(sk);
1021 }
1022 EXPORT_SYMBOL(inet_csk_destroy_sock);
1023 
1024 /* This function allows to force a closure of a socket after the call to
1025  * tcp/dccp_create_openreq_child().
1026  */
1027 void inet_csk_prepare_forced_close(struct sock *sk)
1028 	__releases(&sk->sk_lock.slock)
1029 {
1030 	/* sk_clone_lock locked the socket and set refcnt to 2 */
1031 	bh_unlock_sock(sk);
1032 	sock_put(sk);
1033 	inet_csk_prepare_for_destroy_sock(sk);
1034 	inet_sk(sk)->inet_num = 0;
1035 }
1036 EXPORT_SYMBOL(inet_csk_prepare_forced_close);
1037 
1038 int inet_csk_listen_start(struct sock *sk, int backlog)
1039 {
1040 	struct inet_connection_sock *icsk = inet_csk(sk);
1041 	struct inet_sock *inet = inet_sk(sk);
1042 	int err = -EADDRINUSE;
1043 
1044 	reqsk_queue_alloc(&icsk->icsk_accept_queue);
1045 
1046 	sk->sk_ack_backlog = 0;
1047 	inet_csk_delack_init(sk);
1048 
1049 	/* There is race window here: we announce ourselves listening,
1050 	 * but this transition is still not validated by get_port().
1051 	 * It is OK, because this socket enters to hash table only
1052 	 * after validation is complete.
1053 	 */
1054 	inet_sk_state_store(sk, TCP_LISTEN);
1055 	if (!sk->sk_prot->get_port(sk, inet->inet_num)) {
1056 		inet->inet_sport = htons(inet->inet_num);
1057 
1058 		sk_dst_reset(sk);
1059 		err = sk->sk_prot->hash(sk);
1060 
1061 		if (likely(!err))
1062 			return 0;
1063 	}
1064 
1065 	inet_sk_set_state(sk, TCP_CLOSE);
1066 	return err;
1067 }
1068 EXPORT_SYMBOL_GPL(inet_csk_listen_start);
1069 
1070 static void inet_child_forget(struct sock *sk, struct request_sock *req,
1071 			      struct sock *child)
1072 {
1073 	sk->sk_prot->disconnect(child, O_NONBLOCK);
1074 
1075 	sock_orphan(child);
1076 
1077 	this_cpu_inc(*sk->sk_prot->orphan_count);
1078 
1079 	if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->tfo_listener) {
1080 		BUG_ON(rcu_access_pointer(tcp_sk(child)->fastopen_rsk) != req);
1081 		BUG_ON(sk != req->rsk_listener);
1082 
1083 		/* Paranoid, to prevent race condition if
1084 		 * an inbound pkt destined for child is
1085 		 * blocked by sock lock in tcp_v4_rcv().
1086 		 * Also to satisfy an assertion in
1087 		 * tcp_v4_destroy_sock().
1088 		 */
1089 		RCU_INIT_POINTER(tcp_sk(child)->fastopen_rsk, NULL);
1090 	}
1091 	inet_csk_destroy_sock(child);
1092 }
1093 
1094 struct sock *inet_csk_reqsk_queue_add(struct sock *sk,
1095 				      struct request_sock *req,
1096 				      struct sock *child)
1097 {
1098 	struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
1099 
1100 	spin_lock(&queue->rskq_lock);
1101 	if (unlikely(sk->sk_state != TCP_LISTEN)) {
1102 		inet_child_forget(sk, req, child);
1103 		child = NULL;
1104 	} else {
1105 		req->sk = child;
1106 		req->dl_next = NULL;
1107 		if (queue->rskq_accept_head == NULL)
1108 			WRITE_ONCE(queue->rskq_accept_head, req);
1109 		else
1110 			queue->rskq_accept_tail->dl_next = req;
1111 		queue->rskq_accept_tail = req;
1112 		sk_acceptq_added(sk);
1113 	}
1114 	spin_unlock(&queue->rskq_lock);
1115 	return child;
1116 }
1117 EXPORT_SYMBOL(inet_csk_reqsk_queue_add);
1118 
1119 struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child,
1120 					 struct request_sock *req, bool own_req)
1121 {
1122 	if (own_req) {
1123 		inet_csk_reqsk_queue_drop(req->rsk_listener, req);
1124 		reqsk_queue_removed(&inet_csk(req->rsk_listener)->icsk_accept_queue, req);
1125 
1126 		if (sk != req->rsk_listener) {
1127 			/* another listening sk has been selected,
1128 			 * migrate the req to it.
1129 			 */
1130 			struct request_sock *nreq;
1131 
1132 			/* hold a refcnt for the nreq->rsk_listener
1133 			 * which is assigned in inet_reqsk_clone()
1134 			 */
1135 			sock_hold(sk);
1136 			nreq = inet_reqsk_clone(req, sk);
1137 			if (!nreq) {
1138 				inet_child_forget(sk, req, child);
1139 				goto child_put;
1140 			}
1141 
1142 			refcount_set(&nreq->rsk_refcnt, 1);
1143 			if (inet_csk_reqsk_queue_add(sk, nreq, child)) {
1144 				__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQSUCCESS);
1145 				reqsk_migrate_reset(req);
1146 				reqsk_put(req);
1147 				return child;
1148 			}
1149 
1150 			__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);
1151 			reqsk_migrate_reset(nreq);
1152 			__reqsk_free(nreq);
1153 		} else if (inet_csk_reqsk_queue_add(sk, req, child)) {
1154 			return child;
1155 		}
1156 	}
1157 	/* Too bad, another child took ownership of the request, undo. */
1158 child_put:
1159 	bh_unlock_sock(child);
1160 	sock_put(child);
1161 	return NULL;
1162 }
1163 EXPORT_SYMBOL(inet_csk_complete_hashdance);
1164 
1165 /*
1166  *	This routine closes sockets which have been at least partially
1167  *	opened, but not yet accepted.
1168  */
1169 void inet_csk_listen_stop(struct sock *sk)
1170 {
1171 	struct inet_connection_sock *icsk = inet_csk(sk);
1172 	struct request_sock_queue *queue = &icsk->icsk_accept_queue;
1173 	struct request_sock *next, *req;
1174 
1175 	/* Following specs, it would be better either to send FIN
1176 	 * (and enter FIN-WAIT-1, it is normal close)
1177 	 * or to send active reset (abort).
1178 	 * Certainly, it is pretty dangerous while synflood, but it is
1179 	 * bad justification for our negligence 8)
1180 	 * To be honest, we are not able to make either
1181 	 * of the variants now.			--ANK
1182 	 */
1183 	while ((req = reqsk_queue_remove(queue, sk)) != NULL) {
1184 		struct sock *child = req->sk, *nsk;
1185 		struct request_sock *nreq;
1186 
1187 		local_bh_disable();
1188 		bh_lock_sock(child);
1189 		WARN_ON(sock_owned_by_user(child));
1190 		sock_hold(child);
1191 
1192 		nsk = reuseport_migrate_sock(sk, child, NULL);
1193 		if (nsk) {
1194 			nreq = inet_reqsk_clone(req, nsk);
1195 			if (nreq) {
1196 				refcount_set(&nreq->rsk_refcnt, 1);
1197 
1198 				if (inet_csk_reqsk_queue_add(nsk, nreq, child)) {
1199 					__NET_INC_STATS(sock_net(nsk),
1200 							LINUX_MIB_TCPMIGRATEREQSUCCESS);
1201 					reqsk_migrate_reset(req);
1202 				} else {
1203 					__NET_INC_STATS(sock_net(nsk),
1204 							LINUX_MIB_TCPMIGRATEREQFAILURE);
1205 					reqsk_migrate_reset(nreq);
1206 					__reqsk_free(nreq);
1207 				}
1208 
1209 				/* inet_csk_reqsk_queue_add() has already
1210 				 * called inet_child_forget() on failure case.
1211 				 */
1212 				goto skip_child_forget;
1213 			}
1214 		}
1215 
1216 		inet_child_forget(sk, req, child);
1217 skip_child_forget:
1218 		reqsk_put(req);
1219 		bh_unlock_sock(child);
1220 		local_bh_enable();
1221 		sock_put(child);
1222 
1223 		cond_resched();
1224 	}
1225 	if (queue->fastopenq.rskq_rst_head) {
1226 		/* Free all the reqs queued in rskq_rst_head. */
1227 		spin_lock_bh(&queue->fastopenq.lock);
1228 		req = queue->fastopenq.rskq_rst_head;
1229 		queue->fastopenq.rskq_rst_head = NULL;
1230 		spin_unlock_bh(&queue->fastopenq.lock);
1231 		while (req != NULL) {
1232 			next = req->dl_next;
1233 			reqsk_put(req);
1234 			req = next;
1235 		}
1236 	}
1237 	WARN_ON_ONCE(sk->sk_ack_backlog);
1238 }
1239 EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
1240 
1241 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
1242 {
1243 	struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
1244 	const struct inet_sock *inet = inet_sk(sk);
1245 
1246 	sin->sin_family		= AF_INET;
1247 	sin->sin_addr.s_addr	= inet->inet_daddr;
1248 	sin->sin_port		= inet->inet_dport;
1249 }
1250 EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);
1251 
1252 static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *fl)
1253 {
1254 	const struct inet_sock *inet = inet_sk(sk);
1255 	const struct ip_options_rcu *inet_opt;
1256 	__be32 daddr = inet->inet_daddr;
1257 	struct flowi4 *fl4;
1258 	struct rtable *rt;
1259 
1260 	rcu_read_lock();
1261 	inet_opt = rcu_dereference(inet->inet_opt);
1262 	if (inet_opt && inet_opt->opt.srr)
1263 		daddr = inet_opt->opt.faddr;
1264 	fl4 = &fl->u.ip4;
1265 	rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr,
1266 				   inet->inet_saddr, inet->inet_dport,
1267 				   inet->inet_sport, sk->sk_protocol,
1268 				   RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
1269 	if (IS_ERR(rt))
1270 		rt = NULL;
1271 	if (rt)
1272 		sk_setup_caps(sk, &rt->dst);
1273 	rcu_read_unlock();
1274 
1275 	return &rt->dst;
1276 }
1277 
1278 struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu)
1279 {
1280 	struct dst_entry *dst = __sk_dst_check(sk, 0);
1281 	struct inet_sock *inet = inet_sk(sk);
1282 
1283 	if (!dst) {
1284 		dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1285 		if (!dst)
1286 			goto out;
1287 	}
1288 	dst->ops->update_pmtu(dst, sk, NULL, mtu, true);
1289 
1290 	dst = __sk_dst_check(sk, 0);
1291 	if (!dst)
1292 		dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1293 out:
1294 	return dst;
1295 }
1296 EXPORT_SYMBOL_GPL(inet_csk_update_pmtu);
1297