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(const 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 void inet_sk_get_local_port_range(const struct sock *sk, int *low, int *high)
134 {
135 	const struct inet_sock *inet = inet_sk(sk);
136 	const struct net *net = sock_net(sk);
137 	int lo, hi, sk_lo, sk_hi;
138 
139 	inet_get_local_port_range(net, &lo, &hi);
140 
141 	sk_lo = inet->local_port_range.lo;
142 	sk_hi = inet->local_port_range.hi;
143 
144 	if (unlikely(lo <= sk_lo && sk_lo <= hi))
145 		lo = sk_lo;
146 	if (unlikely(lo <= sk_hi && sk_hi <= hi))
147 		hi = sk_hi;
148 
149 	*low = lo;
150 	*high = hi;
151 }
152 EXPORT_SYMBOL(inet_sk_get_local_port_range);
153 
154 static bool inet_use_bhash2_on_bind(const struct sock *sk)
155 {
156 #if IS_ENABLED(CONFIG_IPV6)
157 	if (sk->sk_family == AF_INET6) {
158 		int addr_type = ipv6_addr_type(&sk->sk_v6_rcv_saddr);
159 
160 		return addr_type != IPV6_ADDR_ANY &&
161 			addr_type != IPV6_ADDR_MAPPED;
162 	}
163 #endif
164 	return sk->sk_rcv_saddr != htonl(INADDR_ANY);
165 }
166 
167 static bool inet_bind_conflict(const struct sock *sk, struct sock *sk2,
168 			       kuid_t sk_uid, bool relax,
169 			       bool reuseport_cb_ok, bool reuseport_ok)
170 {
171 	int bound_dev_if2;
172 
173 	if (sk == sk2)
174 		return false;
175 
176 	bound_dev_if2 = READ_ONCE(sk2->sk_bound_dev_if);
177 
178 	if (!sk->sk_bound_dev_if || !bound_dev_if2 ||
179 	    sk->sk_bound_dev_if == bound_dev_if2) {
180 		if (sk->sk_reuse && sk2->sk_reuse &&
181 		    sk2->sk_state != TCP_LISTEN) {
182 			if (!relax || (!reuseport_ok && sk->sk_reuseport &&
183 				       sk2->sk_reuseport && reuseport_cb_ok &&
184 				       (sk2->sk_state == TCP_TIME_WAIT ||
185 					uid_eq(sk_uid, sock_i_uid(sk2)))))
186 				return true;
187 		} else if (!reuseport_ok || !sk->sk_reuseport ||
188 			   !sk2->sk_reuseport || !reuseport_cb_ok ||
189 			   (sk2->sk_state != TCP_TIME_WAIT &&
190 			    !uid_eq(sk_uid, sock_i_uid(sk2)))) {
191 			return true;
192 		}
193 	}
194 	return false;
195 }
196 
197 static bool __inet_bhash2_conflict(const struct sock *sk, struct sock *sk2,
198 				   kuid_t sk_uid, bool relax,
199 				   bool reuseport_cb_ok, bool reuseport_ok)
200 {
201 	if (sk->sk_family == AF_INET && ipv6_only_sock(sk2))
202 		return false;
203 
204 	return inet_bind_conflict(sk, sk2, sk_uid, relax,
205 				  reuseport_cb_ok, reuseport_ok);
206 }
207 
208 static bool inet_bhash2_conflict(const struct sock *sk,
209 				 const struct inet_bind2_bucket *tb2,
210 				 kuid_t sk_uid,
211 				 bool relax, bool reuseport_cb_ok,
212 				 bool reuseport_ok)
213 {
214 	struct inet_timewait_sock *tw2;
215 	struct sock *sk2;
216 
217 	sk_for_each_bound_bhash2(sk2, &tb2->owners) {
218 		if (__inet_bhash2_conflict(sk, sk2, sk_uid, relax,
219 					   reuseport_cb_ok, reuseport_ok))
220 			return true;
221 	}
222 
223 	twsk_for_each_bound_bhash2(tw2, &tb2->deathrow) {
224 		sk2 = (struct sock *)tw2;
225 
226 		if (__inet_bhash2_conflict(sk, sk2, sk_uid, relax,
227 					   reuseport_cb_ok, reuseport_ok))
228 			return true;
229 	}
230 
231 	return false;
232 }
233 
234 /* This should be called only when the tb and tb2 hashbuckets' locks are held */
235 static int inet_csk_bind_conflict(const struct sock *sk,
236 				  const struct inet_bind_bucket *tb,
237 				  const struct inet_bind2_bucket *tb2, /* may be null */
238 				  bool relax, bool reuseport_ok)
239 {
240 	bool reuseport_cb_ok;
241 	struct sock_reuseport *reuseport_cb;
242 	kuid_t uid = sock_i_uid((struct sock *)sk);
243 
244 	rcu_read_lock();
245 	reuseport_cb = rcu_dereference(sk->sk_reuseport_cb);
246 	/* paired with WRITE_ONCE() in __reuseport_(add|detach)_closed_sock */
247 	reuseport_cb_ok = !reuseport_cb || READ_ONCE(reuseport_cb->num_closed_socks);
248 	rcu_read_unlock();
249 
250 	/*
251 	 * Unlike other sk lookup places we do not check
252 	 * for sk_net here, since _all_ the socks listed
253 	 * in tb->owners and tb2->owners list belong
254 	 * to the same net - the one this bucket belongs to.
255 	 */
256 
257 	if (!inet_use_bhash2_on_bind(sk)) {
258 		struct sock *sk2;
259 
260 		sk_for_each_bound(sk2, &tb->owners)
261 			if (inet_bind_conflict(sk, sk2, uid, relax,
262 					       reuseport_cb_ok, reuseport_ok) &&
263 			    inet_rcv_saddr_equal(sk, sk2, true))
264 				return true;
265 
266 		return false;
267 	}
268 
269 	/* Conflicts with an existing IPV6_ADDR_ANY (if ipv6) or INADDR_ANY (if
270 	 * ipv4) should have been checked already. We need to do these two
271 	 * checks separately because their spinlocks have to be acquired/released
272 	 * independently of each other, to prevent possible deadlocks
273 	 */
274 	return tb2 && inet_bhash2_conflict(sk, tb2, uid, relax, reuseport_cb_ok,
275 					   reuseport_ok);
276 }
277 
278 /* Determine if there is a bind conflict with an existing IPV6_ADDR_ANY (if ipv6) or
279  * INADDR_ANY (if ipv4) socket.
280  *
281  * Caller must hold bhash hashbucket lock with local bh disabled, to protect
282  * against concurrent binds on the port for addr any
283  */
284 static bool inet_bhash2_addr_any_conflict(const struct sock *sk, int port, int l3mdev,
285 					  bool relax, bool reuseport_ok)
286 {
287 	kuid_t uid = sock_i_uid((struct sock *)sk);
288 	const struct net *net = sock_net(sk);
289 	struct sock_reuseport *reuseport_cb;
290 	struct inet_bind_hashbucket *head2;
291 	struct inet_bind2_bucket *tb2;
292 	bool conflict = false;
293 	bool reuseport_cb_ok;
294 
295 	rcu_read_lock();
296 	reuseport_cb = rcu_dereference(sk->sk_reuseport_cb);
297 	/* paired with WRITE_ONCE() in __reuseport_(add|detach)_closed_sock */
298 	reuseport_cb_ok = !reuseport_cb || READ_ONCE(reuseport_cb->num_closed_socks);
299 	rcu_read_unlock();
300 
301 	head2 = inet_bhash2_addr_any_hashbucket(sk, net, port);
302 
303 	spin_lock(&head2->lock);
304 
305 	inet_bind_bucket_for_each(tb2, &head2->chain) {
306 		if (!inet_bind2_bucket_match_addr_any(tb2, net, port, l3mdev, sk))
307 			continue;
308 
309 		if (!inet_bhash2_conflict(sk, tb2, uid, relax, reuseport_cb_ok,	reuseport_ok))
310 			continue;
311 
312 		conflict = true;
313 		break;
314 	}
315 
316 	spin_unlock(&head2->lock);
317 
318 	return conflict;
319 }
320 
321 /*
322  * Find an open port number for the socket.  Returns with the
323  * inet_bind_hashbucket locks held if successful.
324  */
325 static struct inet_bind_hashbucket *
326 inet_csk_find_open_port(const struct sock *sk, struct inet_bind_bucket **tb_ret,
327 			struct inet_bind2_bucket **tb2_ret,
328 			struct inet_bind_hashbucket **head2_ret, int *port_ret)
329 {
330 	struct inet_hashinfo *hinfo = tcp_or_dccp_get_hashinfo(sk);
331 	int i, low, high, attempt_half, port, l3mdev;
332 	struct inet_bind_hashbucket *head, *head2;
333 	struct net *net = sock_net(sk);
334 	struct inet_bind2_bucket *tb2;
335 	struct inet_bind_bucket *tb;
336 	u32 remaining, offset;
337 	bool relax = false;
338 
339 	l3mdev = inet_sk_bound_l3mdev(sk);
340 ports_exhausted:
341 	attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0;
342 other_half_scan:
343 	inet_sk_get_local_port_range(sk, &low, &high);
344 	high++; /* [32768, 60999] -> [32768, 61000[ */
345 	if (high - low < 4)
346 		attempt_half = 0;
347 	if (attempt_half) {
348 		int half = low + (((high - low) >> 2) << 1);
349 
350 		if (attempt_half == 1)
351 			high = half;
352 		else
353 			low = half;
354 	}
355 	remaining = high - low;
356 	if (likely(remaining > 1))
357 		remaining &= ~1U;
358 
359 	offset = get_random_u32_below(remaining);
360 	/* __inet_hash_connect() favors ports having @low parity
361 	 * We do the opposite to not pollute connect() users.
362 	 */
363 	offset |= 1U;
364 
365 other_parity_scan:
366 	port = low + offset;
367 	for (i = 0; i < remaining; i += 2, port += 2) {
368 		if (unlikely(port >= high))
369 			port -= remaining;
370 		if (inet_is_local_reserved_port(net, port))
371 			continue;
372 		head = &hinfo->bhash[inet_bhashfn(net, port,
373 						  hinfo->bhash_size)];
374 		spin_lock_bh(&head->lock);
375 		if (inet_use_bhash2_on_bind(sk)) {
376 			if (inet_bhash2_addr_any_conflict(sk, port, l3mdev, relax, false))
377 				goto next_port;
378 		}
379 
380 		head2 = inet_bhashfn_portaddr(hinfo, sk, net, port);
381 		spin_lock(&head2->lock);
382 		tb2 = inet_bind2_bucket_find(head2, net, port, l3mdev, sk);
383 		inet_bind_bucket_for_each(tb, &head->chain)
384 			if (inet_bind_bucket_match(tb, net, port, l3mdev)) {
385 				if (!inet_csk_bind_conflict(sk, tb, tb2,
386 							    relax, false))
387 					goto success;
388 				spin_unlock(&head2->lock);
389 				goto next_port;
390 			}
391 		tb = NULL;
392 		goto success;
393 next_port:
394 		spin_unlock_bh(&head->lock);
395 		cond_resched();
396 	}
397 
398 	offset--;
399 	if (!(offset & 1))
400 		goto other_parity_scan;
401 
402 	if (attempt_half == 1) {
403 		/* OK we now try the upper half of the range */
404 		attempt_half = 2;
405 		goto other_half_scan;
406 	}
407 
408 	if (READ_ONCE(net->ipv4.sysctl_ip_autobind_reuse) && !relax) {
409 		/* We still have a chance to connect to different destinations */
410 		relax = true;
411 		goto ports_exhausted;
412 	}
413 	return NULL;
414 success:
415 	*port_ret = port;
416 	*tb_ret = tb;
417 	*tb2_ret = tb2;
418 	*head2_ret = head2;
419 	return head;
420 }
421 
422 static inline int sk_reuseport_match(struct inet_bind_bucket *tb,
423 				     struct sock *sk)
424 {
425 	kuid_t uid = sock_i_uid(sk);
426 
427 	if (tb->fastreuseport <= 0)
428 		return 0;
429 	if (!sk->sk_reuseport)
430 		return 0;
431 	if (rcu_access_pointer(sk->sk_reuseport_cb))
432 		return 0;
433 	if (!uid_eq(tb->fastuid, uid))
434 		return 0;
435 	/* We only need to check the rcv_saddr if this tb was once marked
436 	 * without fastreuseport and then was reset, as we can only know that
437 	 * the fast_*rcv_saddr doesn't have any conflicts with the socks on the
438 	 * owners list.
439 	 */
440 	if (tb->fastreuseport == FASTREUSEPORT_ANY)
441 		return 1;
442 #if IS_ENABLED(CONFIG_IPV6)
443 	if (tb->fast_sk_family == AF_INET6)
444 		return ipv6_rcv_saddr_equal(&tb->fast_v6_rcv_saddr,
445 					    inet6_rcv_saddr(sk),
446 					    tb->fast_rcv_saddr,
447 					    sk->sk_rcv_saddr,
448 					    tb->fast_ipv6_only,
449 					    ipv6_only_sock(sk), true, false);
450 #endif
451 	return ipv4_rcv_saddr_equal(tb->fast_rcv_saddr, sk->sk_rcv_saddr,
452 				    ipv6_only_sock(sk), true, false);
453 }
454 
455 void inet_csk_update_fastreuse(struct inet_bind_bucket *tb,
456 			       struct sock *sk)
457 {
458 	kuid_t uid = sock_i_uid(sk);
459 	bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
460 
461 	if (hlist_empty(&tb->owners)) {
462 		tb->fastreuse = reuse;
463 		if (sk->sk_reuseport) {
464 			tb->fastreuseport = FASTREUSEPORT_ANY;
465 			tb->fastuid = uid;
466 			tb->fast_rcv_saddr = sk->sk_rcv_saddr;
467 			tb->fast_ipv6_only = ipv6_only_sock(sk);
468 			tb->fast_sk_family = sk->sk_family;
469 #if IS_ENABLED(CONFIG_IPV6)
470 			tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
471 #endif
472 		} else {
473 			tb->fastreuseport = 0;
474 		}
475 	} else {
476 		if (!reuse)
477 			tb->fastreuse = 0;
478 		if (sk->sk_reuseport) {
479 			/* We didn't match or we don't have fastreuseport set on
480 			 * the tb, but we have sk_reuseport set on this socket
481 			 * and we know that there are no bind conflicts with
482 			 * this socket in this tb, so reset our tb's reuseport
483 			 * settings so that any subsequent sockets that match
484 			 * our current socket will be put on the fast path.
485 			 *
486 			 * If we reset we need to set FASTREUSEPORT_STRICT so we
487 			 * do extra checking for all subsequent sk_reuseport
488 			 * socks.
489 			 */
490 			if (!sk_reuseport_match(tb, sk)) {
491 				tb->fastreuseport = FASTREUSEPORT_STRICT;
492 				tb->fastuid = uid;
493 				tb->fast_rcv_saddr = sk->sk_rcv_saddr;
494 				tb->fast_ipv6_only = ipv6_only_sock(sk);
495 				tb->fast_sk_family = sk->sk_family;
496 #if IS_ENABLED(CONFIG_IPV6)
497 				tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
498 #endif
499 			}
500 		} else {
501 			tb->fastreuseport = 0;
502 		}
503 	}
504 }
505 
506 /* Obtain a reference to a local port for the given sock,
507  * if snum is zero it means select any available local port.
508  * We try to allocate an odd port (and leave even ports for connect())
509  */
510 int inet_csk_get_port(struct sock *sk, unsigned short snum)
511 {
512 	struct inet_hashinfo *hinfo = tcp_or_dccp_get_hashinfo(sk);
513 	bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
514 	bool found_port = false, check_bind_conflict = true;
515 	bool bhash_created = false, bhash2_created = false;
516 	int ret = -EADDRINUSE, port = snum, l3mdev;
517 	struct inet_bind_hashbucket *head, *head2;
518 	struct inet_bind2_bucket *tb2 = NULL;
519 	struct inet_bind_bucket *tb = NULL;
520 	bool head2_lock_acquired = false;
521 	struct net *net = sock_net(sk);
522 
523 	l3mdev = inet_sk_bound_l3mdev(sk);
524 
525 	if (!port) {
526 		head = inet_csk_find_open_port(sk, &tb, &tb2, &head2, &port);
527 		if (!head)
528 			return ret;
529 
530 		head2_lock_acquired = true;
531 
532 		if (tb && tb2)
533 			goto success;
534 		found_port = true;
535 	} else {
536 		head = &hinfo->bhash[inet_bhashfn(net, port,
537 						  hinfo->bhash_size)];
538 		spin_lock_bh(&head->lock);
539 		inet_bind_bucket_for_each(tb, &head->chain)
540 			if (inet_bind_bucket_match(tb, net, port, l3mdev))
541 				break;
542 	}
543 
544 	if (!tb) {
545 		tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep, net,
546 					     head, port, l3mdev);
547 		if (!tb)
548 			goto fail_unlock;
549 		bhash_created = true;
550 	}
551 
552 	if (!found_port) {
553 		if (!hlist_empty(&tb->owners)) {
554 			if (sk->sk_reuse == SK_FORCE_REUSE ||
555 			    (tb->fastreuse > 0 && reuse) ||
556 			    sk_reuseport_match(tb, sk))
557 				check_bind_conflict = false;
558 		}
559 
560 		if (check_bind_conflict && inet_use_bhash2_on_bind(sk)) {
561 			if (inet_bhash2_addr_any_conflict(sk, port, l3mdev, true, true))
562 				goto fail_unlock;
563 		}
564 
565 		head2 = inet_bhashfn_portaddr(hinfo, sk, net, port);
566 		spin_lock(&head2->lock);
567 		head2_lock_acquired = true;
568 		tb2 = inet_bind2_bucket_find(head2, net, port, l3mdev, sk);
569 	}
570 
571 	if (!tb2) {
572 		tb2 = inet_bind2_bucket_create(hinfo->bind2_bucket_cachep,
573 					       net, head2, port, l3mdev, sk);
574 		if (!tb2)
575 			goto fail_unlock;
576 		bhash2_created = true;
577 	}
578 
579 	if (!found_port && check_bind_conflict) {
580 		if (inet_csk_bind_conflict(sk, tb, tb2, true, true))
581 			goto fail_unlock;
582 	}
583 
584 success:
585 	inet_csk_update_fastreuse(tb, sk);
586 
587 	if (!inet_csk(sk)->icsk_bind_hash)
588 		inet_bind_hash(sk, tb, tb2, port);
589 	WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);
590 	WARN_ON(inet_csk(sk)->icsk_bind2_hash != tb2);
591 	ret = 0;
592 
593 fail_unlock:
594 	if (ret) {
595 		if (bhash_created)
596 			inet_bind_bucket_destroy(hinfo->bind_bucket_cachep, tb);
597 		if (bhash2_created)
598 			inet_bind2_bucket_destroy(hinfo->bind2_bucket_cachep,
599 						  tb2);
600 	}
601 	if (head2_lock_acquired)
602 		spin_unlock(&head2->lock);
603 	spin_unlock_bh(&head->lock);
604 	return ret;
605 }
606 EXPORT_SYMBOL_GPL(inet_csk_get_port);
607 
608 /*
609  * Wait for an incoming connection, avoid race conditions. This must be called
610  * with the socket locked.
611  */
612 static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
613 {
614 	struct inet_connection_sock *icsk = inet_csk(sk);
615 	DEFINE_WAIT(wait);
616 	int err;
617 
618 	/*
619 	 * True wake-one mechanism for incoming connections: only
620 	 * one process gets woken up, not the 'whole herd'.
621 	 * Since we do not 'race & poll' for established sockets
622 	 * anymore, the common case will execute the loop only once.
623 	 *
624 	 * Subtle issue: "add_wait_queue_exclusive()" will be added
625 	 * after any current non-exclusive waiters, and we know that
626 	 * it will always _stay_ after any new non-exclusive waiters
627 	 * because all non-exclusive waiters are added at the
628 	 * beginning of the wait-queue. As such, it's ok to "drop"
629 	 * our exclusiveness temporarily when we get woken up without
630 	 * having to remove and re-insert us on the wait queue.
631 	 */
632 	for (;;) {
633 		prepare_to_wait_exclusive(sk_sleep(sk), &wait,
634 					  TASK_INTERRUPTIBLE);
635 		release_sock(sk);
636 		if (reqsk_queue_empty(&icsk->icsk_accept_queue))
637 			timeo = schedule_timeout(timeo);
638 		sched_annotate_sleep();
639 		lock_sock(sk);
640 		err = 0;
641 		if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
642 			break;
643 		err = -EINVAL;
644 		if (sk->sk_state != TCP_LISTEN)
645 			break;
646 		err = sock_intr_errno(timeo);
647 		if (signal_pending(current))
648 			break;
649 		err = -EAGAIN;
650 		if (!timeo)
651 			break;
652 	}
653 	finish_wait(sk_sleep(sk), &wait);
654 	return err;
655 }
656 
657 /*
658  * This will accept the next outstanding connection.
659  */
660 struct sock *inet_csk_accept(struct sock *sk, int flags, int *err, bool kern)
661 {
662 	struct inet_connection_sock *icsk = inet_csk(sk);
663 	struct request_sock_queue *queue = &icsk->icsk_accept_queue;
664 	struct request_sock *req;
665 	struct sock *newsk;
666 	int error;
667 
668 	lock_sock(sk);
669 
670 	/* We need to make sure that this socket is listening,
671 	 * and that it has something pending.
672 	 */
673 	error = -EINVAL;
674 	if (sk->sk_state != TCP_LISTEN)
675 		goto out_err;
676 
677 	/* Find already established connection */
678 	if (reqsk_queue_empty(queue)) {
679 		long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
680 
681 		/* If this is a non blocking socket don't sleep */
682 		error = -EAGAIN;
683 		if (!timeo)
684 			goto out_err;
685 
686 		error = inet_csk_wait_for_connect(sk, timeo);
687 		if (error)
688 			goto out_err;
689 	}
690 	req = reqsk_queue_remove(queue, sk);
691 	newsk = req->sk;
692 
693 	if (sk->sk_protocol == IPPROTO_TCP &&
694 	    tcp_rsk(req)->tfo_listener) {
695 		spin_lock_bh(&queue->fastopenq.lock);
696 		if (tcp_rsk(req)->tfo_listener) {
697 			/* We are still waiting for the final ACK from 3WHS
698 			 * so can't free req now. Instead, we set req->sk to
699 			 * NULL to signify that the child socket is taken
700 			 * so reqsk_fastopen_remove() will free the req
701 			 * when 3WHS finishes (or is aborted).
702 			 */
703 			req->sk = NULL;
704 			req = NULL;
705 		}
706 		spin_unlock_bh(&queue->fastopenq.lock);
707 	}
708 
709 out:
710 	release_sock(sk);
711 	if (newsk && mem_cgroup_sockets_enabled) {
712 		int amt = 0;
713 
714 		/* atomically get the memory usage, set and charge the
715 		 * newsk->sk_memcg.
716 		 */
717 		lock_sock(newsk);
718 
719 		mem_cgroup_sk_alloc(newsk);
720 		if (newsk->sk_memcg) {
721 			/* The socket has not been accepted yet, no need
722 			 * to look at newsk->sk_wmem_queued.
723 			 */
724 			amt = sk_mem_pages(newsk->sk_forward_alloc +
725 					   atomic_read(&newsk->sk_rmem_alloc));
726 		}
727 
728 		if (amt)
729 			mem_cgroup_charge_skmem(newsk->sk_memcg, amt,
730 						GFP_KERNEL | __GFP_NOFAIL);
731 
732 		release_sock(newsk);
733 	}
734 	if (req)
735 		reqsk_put(req);
736 
737 	if (newsk)
738 		inet_init_csk_locks(newsk);
739 
740 	return newsk;
741 out_err:
742 	newsk = NULL;
743 	req = NULL;
744 	*err = error;
745 	goto out;
746 }
747 EXPORT_SYMBOL(inet_csk_accept);
748 
749 /*
750  * Using different timers for retransmit, delayed acks and probes
751  * We may wish use just one timer maintaining a list of expire jiffies
752  * to optimize.
753  */
754 void inet_csk_init_xmit_timers(struct sock *sk,
755 			       void (*retransmit_handler)(struct timer_list *t),
756 			       void (*delack_handler)(struct timer_list *t),
757 			       void (*keepalive_handler)(struct timer_list *t))
758 {
759 	struct inet_connection_sock *icsk = inet_csk(sk);
760 
761 	timer_setup(&icsk->icsk_retransmit_timer, retransmit_handler, 0);
762 	timer_setup(&icsk->icsk_delack_timer, delack_handler, 0);
763 	timer_setup(&sk->sk_timer, keepalive_handler, 0);
764 	icsk->icsk_pending = icsk->icsk_ack.pending = 0;
765 }
766 EXPORT_SYMBOL(inet_csk_init_xmit_timers);
767 
768 void inet_csk_clear_xmit_timers(struct sock *sk)
769 {
770 	struct inet_connection_sock *icsk = inet_csk(sk);
771 
772 	icsk->icsk_pending = icsk->icsk_ack.pending = 0;
773 
774 	sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
775 	sk_stop_timer(sk, &icsk->icsk_delack_timer);
776 	sk_stop_timer(sk, &sk->sk_timer);
777 }
778 EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
779 
780 void inet_csk_clear_xmit_timers_sync(struct sock *sk)
781 {
782 	struct inet_connection_sock *icsk = inet_csk(sk);
783 
784 	/* ongoing timer handlers need to acquire socket lock. */
785 	sock_not_owned_by_me(sk);
786 
787 	icsk->icsk_pending = icsk->icsk_ack.pending = 0;
788 
789 	sk_stop_timer_sync(sk, &icsk->icsk_retransmit_timer);
790 	sk_stop_timer_sync(sk, &icsk->icsk_delack_timer);
791 	sk_stop_timer_sync(sk, &sk->sk_timer);
792 }
793 
794 void inet_csk_delete_keepalive_timer(struct sock *sk)
795 {
796 	sk_stop_timer(sk, &sk->sk_timer);
797 }
798 EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
799 
800 void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
801 {
802 	sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
803 }
804 EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
805 
806 struct dst_entry *inet_csk_route_req(const struct sock *sk,
807 				     struct flowi4 *fl4,
808 				     const struct request_sock *req)
809 {
810 	const struct inet_request_sock *ireq = inet_rsk(req);
811 	struct net *net = read_pnet(&ireq->ireq_net);
812 	struct ip_options_rcu *opt;
813 	struct rtable *rt;
814 
815 	rcu_read_lock();
816 	opt = rcu_dereference(ireq->ireq_opt);
817 
818 	flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
819 			   ip_sock_rt_tos(sk), ip_sock_rt_scope(sk),
820 			   sk->sk_protocol, inet_sk_flowi_flags(sk),
821 			   (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
822 			   ireq->ir_loc_addr, ireq->ir_rmt_port,
823 			   htons(ireq->ir_num), sk->sk_uid);
824 	security_req_classify_flow(req, flowi4_to_flowi_common(fl4));
825 	rt = ip_route_output_flow(net, fl4, sk);
826 	if (IS_ERR(rt))
827 		goto no_route;
828 	if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
829 		goto route_err;
830 	rcu_read_unlock();
831 	return &rt->dst;
832 
833 route_err:
834 	ip_rt_put(rt);
835 no_route:
836 	rcu_read_unlock();
837 	__IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
838 	return NULL;
839 }
840 EXPORT_SYMBOL_GPL(inet_csk_route_req);
841 
842 struct dst_entry *inet_csk_route_child_sock(const struct sock *sk,
843 					    struct sock *newsk,
844 					    const struct request_sock *req)
845 {
846 	const struct inet_request_sock *ireq = inet_rsk(req);
847 	struct net *net = read_pnet(&ireq->ireq_net);
848 	struct inet_sock *newinet = inet_sk(newsk);
849 	struct ip_options_rcu *opt;
850 	struct flowi4 *fl4;
851 	struct rtable *rt;
852 
853 	opt = rcu_dereference(ireq->ireq_opt);
854 	fl4 = &newinet->cork.fl.u.ip4;
855 
856 	flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
857 			   ip_sock_rt_tos(sk), ip_sock_rt_scope(sk),
858 			   sk->sk_protocol, inet_sk_flowi_flags(sk),
859 			   (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
860 			   ireq->ir_loc_addr, ireq->ir_rmt_port,
861 			   htons(ireq->ir_num), sk->sk_uid);
862 	security_req_classify_flow(req, flowi4_to_flowi_common(fl4));
863 	rt = ip_route_output_flow(net, fl4, sk);
864 	if (IS_ERR(rt))
865 		goto no_route;
866 	if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
867 		goto route_err;
868 	return &rt->dst;
869 
870 route_err:
871 	ip_rt_put(rt);
872 no_route:
873 	__IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
874 	return NULL;
875 }
876 EXPORT_SYMBOL_GPL(inet_csk_route_child_sock);
877 
878 /* Decide when to expire the request and when to resend SYN-ACK */
879 static void syn_ack_recalc(struct request_sock *req,
880 			   const int max_syn_ack_retries,
881 			   const u8 rskq_defer_accept,
882 			   int *expire, int *resend)
883 {
884 	if (!rskq_defer_accept) {
885 		*expire = req->num_timeout >= max_syn_ack_retries;
886 		*resend = 1;
887 		return;
888 	}
889 	*expire = req->num_timeout >= max_syn_ack_retries &&
890 		  (!inet_rsk(req)->acked || req->num_timeout >= rskq_defer_accept);
891 	/* Do not resend while waiting for data after ACK,
892 	 * start to resend on end of deferring period to give
893 	 * last chance for data or ACK to create established socket.
894 	 */
895 	*resend = !inet_rsk(req)->acked ||
896 		  req->num_timeout >= rskq_defer_accept - 1;
897 }
898 
899 int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req)
900 {
901 	int err = req->rsk_ops->rtx_syn_ack(parent, req);
902 
903 	if (!err)
904 		req->num_retrans++;
905 	return err;
906 }
907 EXPORT_SYMBOL(inet_rtx_syn_ack);
908 
909 static struct request_sock *inet_reqsk_clone(struct request_sock *req,
910 					     struct sock *sk)
911 {
912 	struct sock *req_sk, *nreq_sk;
913 	struct request_sock *nreq;
914 
915 	nreq = kmem_cache_alloc(req->rsk_ops->slab, GFP_ATOMIC | __GFP_NOWARN);
916 	if (!nreq) {
917 		__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);
918 
919 		/* paired with refcount_inc_not_zero() in reuseport_migrate_sock() */
920 		sock_put(sk);
921 		return NULL;
922 	}
923 
924 	req_sk = req_to_sk(req);
925 	nreq_sk = req_to_sk(nreq);
926 
927 	memcpy(nreq_sk, req_sk,
928 	       offsetof(struct sock, sk_dontcopy_begin));
929 	memcpy(&nreq_sk->sk_dontcopy_end, &req_sk->sk_dontcopy_end,
930 	       req->rsk_ops->obj_size - offsetof(struct sock, sk_dontcopy_end));
931 
932 	sk_node_init(&nreq_sk->sk_node);
933 	nreq_sk->sk_tx_queue_mapping = req_sk->sk_tx_queue_mapping;
934 #ifdef CONFIG_SOCK_RX_QUEUE_MAPPING
935 	nreq_sk->sk_rx_queue_mapping = req_sk->sk_rx_queue_mapping;
936 #endif
937 	nreq_sk->sk_incoming_cpu = req_sk->sk_incoming_cpu;
938 
939 	nreq->rsk_listener = sk;
940 
941 	/* We need not acquire fastopenq->lock
942 	 * because the child socket is locked in inet_csk_listen_stop().
943 	 */
944 	if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(nreq)->tfo_listener)
945 		rcu_assign_pointer(tcp_sk(nreq->sk)->fastopen_rsk, nreq);
946 
947 	return nreq;
948 }
949 
950 static void reqsk_queue_migrated(struct request_sock_queue *queue,
951 				 const struct request_sock *req)
952 {
953 	if (req->num_timeout == 0)
954 		atomic_inc(&queue->young);
955 	atomic_inc(&queue->qlen);
956 }
957 
958 static void reqsk_migrate_reset(struct request_sock *req)
959 {
960 	req->saved_syn = NULL;
961 #if IS_ENABLED(CONFIG_IPV6)
962 	inet_rsk(req)->ipv6_opt = NULL;
963 	inet_rsk(req)->pktopts = NULL;
964 #else
965 	inet_rsk(req)->ireq_opt = NULL;
966 #endif
967 }
968 
969 /* return true if req was found in the ehash table */
970 static bool reqsk_queue_unlink(struct request_sock *req)
971 {
972 	struct sock *sk = req_to_sk(req);
973 	bool found = false;
974 
975 	if (sk_hashed(sk)) {
976 		struct inet_hashinfo *hashinfo = tcp_or_dccp_get_hashinfo(sk);
977 		spinlock_t *lock = inet_ehash_lockp(hashinfo, req->rsk_hash);
978 
979 		spin_lock(lock);
980 		found = __sk_nulls_del_node_init_rcu(sk);
981 		spin_unlock(lock);
982 	}
983 	if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer))
984 		reqsk_put(req);
985 	return found;
986 }
987 
988 bool inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req)
989 {
990 	bool unlinked = reqsk_queue_unlink(req);
991 
992 	if (unlinked) {
993 		reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
994 		reqsk_put(req);
995 	}
996 	return unlinked;
997 }
998 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop);
999 
1000 void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req)
1001 {
1002 	inet_csk_reqsk_queue_drop(sk, req);
1003 	reqsk_put(req);
1004 }
1005 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop_and_put);
1006 
1007 static void reqsk_timer_handler(struct timer_list *t)
1008 {
1009 	struct request_sock *req = from_timer(req, t, rsk_timer);
1010 	struct request_sock *nreq = NULL, *oreq = req;
1011 	struct sock *sk_listener = req->rsk_listener;
1012 	struct inet_connection_sock *icsk;
1013 	struct request_sock_queue *queue;
1014 	struct net *net;
1015 	int max_syn_ack_retries, qlen, expire = 0, resend = 0;
1016 
1017 	if (inet_sk_state_load(sk_listener) != TCP_LISTEN) {
1018 		struct sock *nsk;
1019 
1020 		nsk = reuseport_migrate_sock(sk_listener, req_to_sk(req), NULL);
1021 		if (!nsk)
1022 			goto drop;
1023 
1024 		nreq = inet_reqsk_clone(req, nsk);
1025 		if (!nreq)
1026 			goto drop;
1027 
1028 		/* The new timer for the cloned req can decrease the 2
1029 		 * by calling inet_csk_reqsk_queue_drop_and_put(), so
1030 		 * hold another count to prevent use-after-free and
1031 		 * call reqsk_put() just before return.
1032 		 */
1033 		refcount_set(&nreq->rsk_refcnt, 2 + 1);
1034 		timer_setup(&nreq->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
1035 		reqsk_queue_migrated(&inet_csk(nsk)->icsk_accept_queue, req);
1036 
1037 		req = nreq;
1038 		sk_listener = nsk;
1039 	}
1040 
1041 	icsk = inet_csk(sk_listener);
1042 	net = sock_net(sk_listener);
1043 	max_syn_ack_retries = READ_ONCE(icsk->icsk_syn_retries) ? :
1044 		READ_ONCE(net->ipv4.sysctl_tcp_synack_retries);
1045 	/* Normally all the openreqs are young and become mature
1046 	 * (i.e. converted to established socket) for first timeout.
1047 	 * If synack was not acknowledged for 1 second, it means
1048 	 * one of the following things: synack was lost, ack was lost,
1049 	 * rtt is high or nobody planned to ack (i.e. synflood).
1050 	 * When server is a bit loaded, queue is populated with old
1051 	 * open requests, reducing effective size of queue.
1052 	 * When server is well loaded, queue size reduces to zero
1053 	 * after several minutes of work. It is not synflood,
1054 	 * it is normal operation. The solution is pruning
1055 	 * too old entries overriding normal timeout, when
1056 	 * situation becomes dangerous.
1057 	 *
1058 	 * Essentially, we reserve half of room for young
1059 	 * embrions; and abort old ones without pity, if old
1060 	 * ones are about to clog our table.
1061 	 */
1062 	queue = &icsk->icsk_accept_queue;
1063 	qlen = reqsk_queue_len(queue);
1064 	if ((qlen << 1) > max(8U, READ_ONCE(sk_listener->sk_max_ack_backlog))) {
1065 		int young = reqsk_queue_len_young(queue) << 1;
1066 
1067 		while (max_syn_ack_retries > 2) {
1068 			if (qlen < young)
1069 				break;
1070 			max_syn_ack_retries--;
1071 			young <<= 1;
1072 		}
1073 	}
1074 	syn_ack_recalc(req, max_syn_ack_retries, READ_ONCE(queue->rskq_defer_accept),
1075 		       &expire, &resend);
1076 	req->rsk_ops->syn_ack_timeout(req);
1077 	if (!expire &&
1078 	    (!resend ||
1079 	     !inet_rtx_syn_ack(sk_listener, req) ||
1080 	     inet_rsk(req)->acked)) {
1081 		if (req->num_timeout++ == 0)
1082 			atomic_dec(&queue->young);
1083 		mod_timer(&req->rsk_timer, jiffies + reqsk_timeout(req, TCP_RTO_MAX));
1084 
1085 		if (!nreq)
1086 			return;
1087 
1088 		if (!inet_ehash_insert(req_to_sk(nreq), req_to_sk(oreq), NULL)) {
1089 			/* delete timer */
1090 			inet_csk_reqsk_queue_drop(sk_listener, nreq);
1091 			goto no_ownership;
1092 		}
1093 
1094 		__NET_INC_STATS(net, LINUX_MIB_TCPMIGRATEREQSUCCESS);
1095 		reqsk_migrate_reset(oreq);
1096 		reqsk_queue_removed(&inet_csk(oreq->rsk_listener)->icsk_accept_queue, oreq);
1097 		reqsk_put(oreq);
1098 
1099 		reqsk_put(nreq);
1100 		return;
1101 	}
1102 
1103 	/* Even if we can clone the req, we may need not retransmit any more
1104 	 * SYN+ACKs (nreq->num_timeout > max_syn_ack_retries, etc), or another
1105 	 * CPU may win the "own_req" race so that inet_ehash_insert() fails.
1106 	 */
1107 	if (nreq) {
1108 		__NET_INC_STATS(net, LINUX_MIB_TCPMIGRATEREQFAILURE);
1109 no_ownership:
1110 		reqsk_migrate_reset(nreq);
1111 		reqsk_queue_removed(queue, nreq);
1112 		__reqsk_free(nreq);
1113 	}
1114 
1115 drop:
1116 	inet_csk_reqsk_queue_drop_and_put(oreq->rsk_listener, oreq);
1117 }
1118 
1119 static void reqsk_queue_hash_req(struct request_sock *req,
1120 				 unsigned long timeout)
1121 {
1122 	timer_setup(&req->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
1123 	mod_timer(&req->rsk_timer, jiffies + timeout);
1124 
1125 	inet_ehash_insert(req_to_sk(req), NULL, NULL);
1126 	/* before letting lookups find us, make sure all req fields
1127 	 * are committed to memory and refcnt initialized.
1128 	 */
1129 	smp_wmb();
1130 	refcount_set(&req->rsk_refcnt, 2 + 1);
1131 }
1132 
1133 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
1134 				   unsigned long timeout)
1135 {
1136 	reqsk_queue_hash_req(req, timeout);
1137 	inet_csk_reqsk_queue_added(sk);
1138 }
1139 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
1140 
1141 static void inet_clone_ulp(const struct request_sock *req, struct sock *newsk,
1142 			   const gfp_t priority)
1143 {
1144 	struct inet_connection_sock *icsk = inet_csk(newsk);
1145 
1146 	if (!icsk->icsk_ulp_ops)
1147 		return;
1148 
1149 	icsk->icsk_ulp_ops->clone(req, newsk, priority);
1150 }
1151 
1152 /**
1153  *	inet_csk_clone_lock - clone an inet socket, and lock its clone
1154  *	@sk: the socket to clone
1155  *	@req: request_sock
1156  *	@priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
1157  *
1158  *	Caller must unlock socket even in error path (bh_unlock_sock(newsk))
1159  */
1160 struct sock *inet_csk_clone_lock(const struct sock *sk,
1161 				 const struct request_sock *req,
1162 				 const gfp_t priority)
1163 {
1164 	struct sock *newsk = sk_clone_lock(sk, priority);
1165 
1166 	if (newsk) {
1167 		struct inet_connection_sock *newicsk = inet_csk(newsk);
1168 
1169 		inet_sk_set_state(newsk, TCP_SYN_RECV);
1170 		newicsk->icsk_bind_hash = NULL;
1171 		newicsk->icsk_bind2_hash = NULL;
1172 
1173 		inet_sk(newsk)->inet_dport = inet_rsk(req)->ir_rmt_port;
1174 		inet_sk(newsk)->inet_num = inet_rsk(req)->ir_num;
1175 		inet_sk(newsk)->inet_sport = htons(inet_rsk(req)->ir_num);
1176 
1177 		/* listeners have SOCK_RCU_FREE, not the children */
1178 		sock_reset_flag(newsk, SOCK_RCU_FREE);
1179 
1180 		inet_sk(newsk)->mc_list = NULL;
1181 
1182 		newsk->sk_mark = inet_rsk(req)->ir_mark;
1183 		atomic64_set(&newsk->sk_cookie,
1184 			     atomic64_read(&inet_rsk(req)->ir_cookie));
1185 
1186 		newicsk->icsk_retransmits = 0;
1187 		newicsk->icsk_backoff	  = 0;
1188 		newicsk->icsk_probes_out  = 0;
1189 		newicsk->icsk_probes_tstamp = 0;
1190 
1191 		/* Deinitialize accept_queue to trap illegal accesses. */
1192 		memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
1193 
1194 		inet_clone_ulp(req, newsk, priority);
1195 
1196 		security_inet_csk_clone(newsk, req);
1197 	}
1198 	return newsk;
1199 }
1200 EXPORT_SYMBOL_GPL(inet_csk_clone_lock);
1201 
1202 /*
1203  * At this point, there should be no process reference to this
1204  * socket, and thus no user references at all.  Therefore we
1205  * can assume the socket waitqueue is inactive and nobody will
1206  * try to jump onto it.
1207  */
1208 void inet_csk_destroy_sock(struct sock *sk)
1209 {
1210 	WARN_ON(sk->sk_state != TCP_CLOSE);
1211 	WARN_ON(!sock_flag(sk, SOCK_DEAD));
1212 
1213 	/* It cannot be in hash table! */
1214 	WARN_ON(!sk_unhashed(sk));
1215 
1216 	/* If it has not 0 inet_sk(sk)->inet_num, it must be bound */
1217 	WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash);
1218 
1219 	sk->sk_prot->destroy(sk);
1220 
1221 	sk_stream_kill_queues(sk);
1222 
1223 	xfrm_sk_free_policy(sk);
1224 
1225 	this_cpu_dec(*sk->sk_prot->orphan_count);
1226 
1227 	sock_put(sk);
1228 }
1229 EXPORT_SYMBOL(inet_csk_destroy_sock);
1230 
1231 /* This function allows to force a closure of a socket after the call to
1232  * tcp/dccp_create_openreq_child().
1233  */
1234 void inet_csk_prepare_forced_close(struct sock *sk)
1235 	__releases(&sk->sk_lock.slock)
1236 {
1237 	/* sk_clone_lock locked the socket and set refcnt to 2 */
1238 	bh_unlock_sock(sk);
1239 	sock_put(sk);
1240 	inet_csk_prepare_for_destroy_sock(sk);
1241 	inet_sk(sk)->inet_num = 0;
1242 }
1243 EXPORT_SYMBOL(inet_csk_prepare_forced_close);
1244 
1245 static int inet_ulp_can_listen(const struct sock *sk)
1246 {
1247 	const struct inet_connection_sock *icsk = inet_csk(sk);
1248 
1249 	if (icsk->icsk_ulp_ops && !icsk->icsk_ulp_ops->clone)
1250 		return -EINVAL;
1251 
1252 	return 0;
1253 }
1254 
1255 int inet_csk_listen_start(struct sock *sk)
1256 {
1257 	struct inet_connection_sock *icsk = inet_csk(sk);
1258 	struct inet_sock *inet = inet_sk(sk);
1259 	int err;
1260 
1261 	err = inet_ulp_can_listen(sk);
1262 	if (unlikely(err))
1263 		return err;
1264 
1265 	reqsk_queue_alloc(&icsk->icsk_accept_queue);
1266 
1267 	sk->sk_ack_backlog = 0;
1268 	inet_csk_delack_init(sk);
1269 
1270 	/* There is race window here: we announce ourselves listening,
1271 	 * but this transition is still not validated by get_port().
1272 	 * It is OK, because this socket enters to hash table only
1273 	 * after validation is complete.
1274 	 */
1275 	inet_sk_state_store(sk, TCP_LISTEN);
1276 	err = sk->sk_prot->get_port(sk, inet->inet_num);
1277 	if (!err) {
1278 		inet->inet_sport = htons(inet->inet_num);
1279 
1280 		sk_dst_reset(sk);
1281 		err = sk->sk_prot->hash(sk);
1282 
1283 		if (likely(!err))
1284 			return 0;
1285 	}
1286 
1287 	inet_sk_set_state(sk, TCP_CLOSE);
1288 	return err;
1289 }
1290 EXPORT_SYMBOL_GPL(inet_csk_listen_start);
1291 
1292 static void inet_child_forget(struct sock *sk, struct request_sock *req,
1293 			      struct sock *child)
1294 {
1295 	sk->sk_prot->disconnect(child, O_NONBLOCK);
1296 
1297 	sock_orphan(child);
1298 
1299 	this_cpu_inc(*sk->sk_prot->orphan_count);
1300 
1301 	if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->tfo_listener) {
1302 		BUG_ON(rcu_access_pointer(tcp_sk(child)->fastopen_rsk) != req);
1303 		BUG_ON(sk != req->rsk_listener);
1304 
1305 		/* Paranoid, to prevent race condition if
1306 		 * an inbound pkt destined for child is
1307 		 * blocked by sock lock in tcp_v4_rcv().
1308 		 * Also to satisfy an assertion in
1309 		 * tcp_v4_destroy_sock().
1310 		 */
1311 		RCU_INIT_POINTER(tcp_sk(child)->fastopen_rsk, NULL);
1312 	}
1313 	inet_csk_destroy_sock(child);
1314 }
1315 
1316 struct sock *inet_csk_reqsk_queue_add(struct sock *sk,
1317 				      struct request_sock *req,
1318 				      struct sock *child)
1319 {
1320 	struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
1321 
1322 	spin_lock(&queue->rskq_lock);
1323 	if (unlikely(sk->sk_state != TCP_LISTEN)) {
1324 		inet_child_forget(sk, req, child);
1325 		child = NULL;
1326 	} else {
1327 		req->sk = child;
1328 		req->dl_next = NULL;
1329 		if (queue->rskq_accept_head == NULL)
1330 			WRITE_ONCE(queue->rskq_accept_head, req);
1331 		else
1332 			queue->rskq_accept_tail->dl_next = req;
1333 		queue->rskq_accept_tail = req;
1334 		sk_acceptq_added(sk);
1335 	}
1336 	spin_unlock(&queue->rskq_lock);
1337 	return child;
1338 }
1339 EXPORT_SYMBOL(inet_csk_reqsk_queue_add);
1340 
1341 struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child,
1342 					 struct request_sock *req, bool own_req)
1343 {
1344 	if (own_req) {
1345 		inet_csk_reqsk_queue_drop(req->rsk_listener, req);
1346 		reqsk_queue_removed(&inet_csk(req->rsk_listener)->icsk_accept_queue, req);
1347 
1348 		if (sk != req->rsk_listener) {
1349 			/* another listening sk has been selected,
1350 			 * migrate the req to it.
1351 			 */
1352 			struct request_sock *nreq;
1353 
1354 			/* hold a refcnt for the nreq->rsk_listener
1355 			 * which is assigned in inet_reqsk_clone()
1356 			 */
1357 			sock_hold(sk);
1358 			nreq = inet_reqsk_clone(req, sk);
1359 			if (!nreq) {
1360 				inet_child_forget(sk, req, child);
1361 				goto child_put;
1362 			}
1363 
1364 			refcount_set(&nreq->rsk_refcnt, 1);
1365 			if (inet_csk_reqsk_queue_add(sk, nreq, child)) {
1366 				__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQSUCCESS);
1367 				reqsk_migrate_reset(req);
1368 				reqsk_put(req);
1369 				return child;
1370 			}
1371 
1372 			__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);
1373 			reqsk_migrate_reset(nreq);
1374 			__reqsk_free(nreq);
1375 		} else if (inet_csk_reqsk_queue_add(sk, req, child)) {
1376 			return child;
1377 		}
1378 	}
1379 	/* Too bad, another child took ownership of the request, undo. */
1380 child_put:
1381 	bh_unlock_sock(child);
1382 	sock_put(child);
1383 	return NULL;
1384 }
1385 EXPORT_SYMBOL(inet_csk_complete_hashdance);
1386 
1387 /*
1388  *	This routine closes sockets which have been at least partially
1389  *	opened, but not yet accepted.
1390  */
1391 void inet_csk_listen_stop(struct sock *sk)
1392 {
1393 	struct inet_connection_sock *icsk = inet_csk(sk);
1394 	struct request_sock_queue *queue = &icsk->icsk_accept_queue;
1395 	struct request_sock *next, *req;
1396 
1397 	/* Following specs, it would be better either to send FIN
1398 	 * (and enter FIN-WAIT-1, it is normal close)
1399 	 * or to send active reset (abort).
1400 	 * Certainly, it is pretty dangerous while synflood, but it is
1401 	 * bad justification for our negligence 8)
1402 	 * To be honest, we are not able to make either
1403 	 * of the variants now.			--ANK
1404 	 */
1405 	while ((req = reqsk_queue_remove(queue, sk)) != NULL) {
1406 		struct sock *child = req->sk, *nsk;
1407 		struct request_sock *nreq;
1408 
1409 		local_bh_disable();
1410 		bh_lock_sock(child);
1411 		WARN_ON(sock_owned_by_user(child));
1412 		sock_hold(child);
1413 
1414 		nsk = reuseport_migrate_sock(sk, child, NULL);
1415 		if (nsk) {
1416 			nreq = inet_reqsk_clone(req, nsk);
1417 			if (nreq) {
1418 				refcount_set(&nreq->rsk_refcnt, 1);
1419 
1420 				if (inet_csk_reqsk_queue_add(nsk, nreq, child)) {
1421 					__NET_INC_STATS(sock_net(nsk),
1422 							LINUX_MIB_TCPMIGRATEREQSUCCESS);
1423 					reqsk_migrate_reset(req);
1424 				} else {
1425 					__NET_INC_STATS(sock_net(nsk),
1426 							LINUX_MIB_TCPMIGRATEREQFAILURE);
1427 					reqsk_migrate_reset(nreq);
1428 					__reqsk_free(nreq);
1429 				}
1430 
1431 				/* inet_csk_reqsk_queue_add() has already
1432 				 * called inet_child_forget() on failure case.
1433 				 */
1434 				goto skip_child_forget;
1435 			}
1436 		}
1437 
1438 		inet_child_forget(sk, req, child);
1439 skip_child_forget:
1440 		reqsk_put(req);
1441 		bh_unlock_sock(child);
1442 		local_bh_enable();
1443 		sock_put(child);
1444 
1445 		cond_resched();
1446 	}
1447 	if (queue->fastopenq.rskq_rst_head) {
1448 		/* Free all the reqs queued in rskq_rst_head. */
1449 		spin_lock_bh(&queue->fastopenq.lock);
1450 		req = queue->fastopenq.rskq_rst_head;
1451 		queue->fastopenq.rskq_rst_head = NULL;
1452 		spin_unlock_bh(&queue->fastopenq.lock);
1453 		while (req != NULL) {
1454 			next = req->dl_next;
1455 			reqsk_put(req);
1456 			req = next;
1457 		}
1458 	}
1459 	WARN_ON_ONCE(sk->sk_ack_backlog);
1460 }
1461 EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
1462 
1463 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
1464 {
1465 	struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
1466 	const struct inet_sock *inet = inet_sk(sk);
1467 
1468 	sin->sin_family		= AF_INET;
1469 	sin->sin_addr.s_addr	= inet->inet_daddr;
1470 	sin->sin_port		= inet->inet_dport;
1471 }
1472 EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);
1473 
1474 static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *fl)
1475 {
1476 	const struct inet_sock *inet = inet_sk(sk);
1477 	const struct ip_options_rcu *inet_opt;
1478 	__be32 daddr = inet->inet_daddr;
1479 	struct flowi4 *fl4;
1480 	struct rtable *rt;
1481 
1482 	rcu_read_lock();
1483 	inet_opt = rcu_dereference(inet->inet_opt);
1484 	if (inet_opt && inet_opt->opt.srr)
1485 		daddr = inet_opt->opt.faddr;
1486 	fl4 = &fl->u.ip4;
1487 	rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr,
1488 				   inet->inet_saddr, inet->inet_dport,
1489 				   inet->inet_sport, sk->sk_protocol,
1490 				   RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
1491 	if (IS_ERR(rt))
1492 		rt = NULL;
1493 	if (rt)
1494 		sk_setup_caps(sk, &rt->dst);
1495 	rcu_read_unlock();
1496 
1497 	return &rt->dst;
1498 }
1499 
1500 struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu)
1501 {
1502 	struct dst_entry *dst = __sk_dst_check(sk, 0);
1503 	struct inet_sock *inet = inet_sk(sk);
1504 
1505 	if (!dst) {
1506 		dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1507 		if (!dst)
1508 			goto out;
1509 	}
1510 	dst->ops->update_pmtu(dst, sk, NULL, mtu, true);
1511 
1512 	dst = __sk_dst_check(sk, 0);
1513 	if (!dst)
1514 		dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1515 out:
1516 	return dst;
1517 }
1518 EXPORT_SYMBOL_GPL(inet_csk_update_pmtu);
1519