1 /*
2  * INET		An implementation of the TCP/IP protocol suite for the LINUX
3  *		operating system.  INET is implemented using the  BSD Socket
4  *		interface as the means of communication with the user level.
5  *
6  *		Support for INET connection oriented protocols.
7  *
8  * Authors:	See the TCP sources
9  *
10  *		This program is free software; you can redistribute it and/or
11  *		modify it under the terms of the GNU General Public License
12  *		as published by the Free Software Foundation; either version
13  *		2 of the License, or(at your option) any later version.
14  */
15 
16 #include <linux/module.h>
17 #include <linux/jhash.h>
18 
19 #include <net/inet_connection_sock.h>
20 #include <net/inet_hashtables.h>
21 #include <net/inet_timewait_sock.h>
22 #include <net/ip.h>
23 #include <net/route.h>
24 #include <net/tcp_states.h>
25 #include <net/xfrm.h>
26 
27 #ifdef INET_CSK_DEBUG
28 const char inet_csk_timer_bug_msg[] = "inet_csk BUG: unknown timer value\n";
29 EXPORT_SYMBOL(inet_csk_timer_bug_msg);
30 #endif
31 
32 /*
33  * This struct holds the first and last local port number.
34  */
35 struct local_ports sysctl_local_ports __read_mostly = {
36 	.lock = SEQLOCK_UNLOCKED,
37 	.range = { 32768, 61000 },
38 };
39 
40 void inet_get_local_port_range(int *low, int *high)
41 {
42 	unsigned seq;
43 	do {
44 		seq = read_seqbegin(&sysctl_local_ports.lock);
45 
46 		*low = sysctl_local_ports.range[0];
47 		*high = sysctl_local_ports.range[1];
48 	} while (read_seqretry(&sysctl_local_ports.lock, seq));
49 }
50 EXPORT_SYMBOL(inet_get_local_port_range);
51 
52 int inet_csk_bind_conflict(const struct sock *sk,
53 			   const struct inet_bind_bucket *tb)
54 {
55 	const __be32 sk_rcv_saddr = inet_rcv_saddr(sk);
56 	struct sock *sk2;
57 	struct hlist_node *node;
58 	int reuse = sk->sk_reuse;
59 
60 	/*
61 	 * Unlike other sk lookup places we do not check
62 	 * for sk_net here, since _all_ the socks listed
63 	 * in tb->owners list belong to the same net - the
64 	 * one this bucket belongs to.
65 	 */
66 
67 	sk_for_each_bound(sk2, node, &tb->owners) {
68 		if (sk != sk2 &&
69 		    !inet_v6_ipv6only(sk2) &&
70 		    (!sk->sk_bound_dev_if ||
71 		     !sk2->sk_bound_dev_if ||
72 		     sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
73 			if (!reuse || !sk2->sk_reuse ||
74 			    sk2->sk_state == TCP_LISTEN) {
75 				const __be32 sk2_rcv_saddr = inet_rcv_saddr(sk2);
76 				if (!sk2_rcv_saddr || !sk_rcv_saddr ||
77 				    sk2_rcv_saddr == sk_rcv_saddr)
78 					break;
79 			}
80 		}
81 	}
82 	return node != NULL;
83 }
84 
85 EXPORT_SYMBOL_GPL(inet_csk_bind_conflict);
86 
87 /* Obtain a reference to a local port for the given sock,
88  * if snum is zero it means select any available local port.
89  */
90 int inet_csk_get_port(struct sock *sk, unsigned short snum)
91 {
92 	struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
93 	struct inet_bind_hashbucket *head;
94 	struct hlist_node *node;
95 	struct inet_bind_bucket *tb;
96 	int ret, attempts = 5;
97 	struct net *net = sock_net(sk);
98 	int smallest_size = -1, smallest_rover;
99 
100 	local_bh_disable();
101 	if (!snum) {
102 		int remaining, rover, low, high;
103 
104 again:
105 		inet_get_local_port_range(&low, &high);
106 		remaining = (high - low) + 1;
107 		smallest_rover = rover = net_random() % remaining + low;
108 
109 		smallest_size = -1;
110 		do {
111 			head = &hashinfo->bhash[inet_bhashfn(net, rover,
112 					hashinfo->bhash_size)];
113 			spin_lock(&head->lock);
114 			inet_bind_bucket_for_each(tb, node, &head->chain)
115 				if (net_eq(ib_net(tb), net) && tb->port == rover) {
116 					if (tb->fastreuse > 0 &&
117 					    sk->sk_reuse &&
118 					    sk->sk_state != TCP_LISTEN &&
119 					    (tb->num_owners < smallest_size || smallest_size == -1)) {
120 						smallest_size = tb->num_owners;
121 						smallest_rover = rover;
122 						if (atomic_read(&hashinfo->bsockets) > (high - low) + 1) {
123 							spin_unlock(&head->lock);
124 							snum = smallest_rover;
125 							goto have_snum;
126 						}
127 					}
128 					goto next;
129 				}
130 			break;
131 		next:
132 			spin_unlock(&head->lock);
133 			if (++rover > high)
134 				rover = low;
135 		} while (--remaining > 0);
136 
137 		/* Exhausted local port range during search?  It is not
138 		 * possible for us to be holding one of the bind hash
139 		 * locks if this test triggers, because if 'remaining'
140 		 * drops to zero, we broke out of the do/while loop at
141 		 * the top level, not from the 'break;' statement.
142 		 */
143 		ret = 1;
144 		if (remaining <= 0) {
145 			if (smallest_size != -1) {
146 				snum = smallest_rover;
147 				goto have_snum;
148 			}
149 			goto fail;
150 		}
151 		/* OK, here is the one we will use.  HEAD is
152 		 * non-NULL and we hold it's mutex.
153 		 */
154 		snum = rover;
155 	} else {
156 have_snum:
157 		head = &hashinfo->bhash[inet_bhashfn(net, snum,
158 				hashinfo->bhash_size)];
159 		spin_lock(&head->lock);
160 		inet_bind_bucket_for_each(tb, node, &head->chain)
161 			if (net_eq(ib_net(tb), net) && tb->port == snum)
162 				goto tb_found;
163 	}
164 	tb = NULL;
165 	goto tb_not_found;
166 tb_found:
167 	if (!hlist_empty(&tb->owners)) {
168 		if (tb->fastreuse > 0 &&
169 		    sk->sk_reuse && sk->sk_state != TCP_LISTEN &&
170 		    smallest_size == -1) {
171 			goto success;
172 		} else {
173 			ret = 1;
174 			if (inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb)) {
175 				if (sk->sk_reuse && sk->sk_state != TCP_LISTEN &&
176 				    smallest_size != -1 && --attempts >= 0) {
177 					spin_unlock(&head->lock);
178 					goto again;
179 				}
180 				goto fail_unlock;
181 			}
182 		}
183 	}
184 tb_not_found:
185 	ret = 1;
186 	if (!tb && (tb = inet_bind_bucket_create(hashinfo->bind_bucket_cachep,
187 					net, head, snum)) == NULL)
188 		goto fail_unlock;
189 	if (hlist_empty(&tb->owners)) {
190 		if (sk->sk_reuse && sk->sk_state != TCP_LISTEN)
191 			tb->fastreuse = 1;
192 		else
193 			tb->fastreuse = 0;
194 	} else if (tb->fastreuse &&
195 		   (!sk->sk_reuse || sk->sk_state == TCP_LISTEN))
196 		tb->fastreuse = 0;
197 success:
198 	if (!inet_csk(sk)->icsk_bind_hash)
199 		inet_bind_hash(sk, tb, snum);
200 	WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);
201 	ret = 0;
202 
203 fail_unlock:
204 	spin_unlock(&head->lock);
205 fail:
206 	local_bh_enable();
207 	return ret;
208 }
209 
210 EXPORT_SYMBOL_GPL(inet_csk_get_port);
211 
212 /*
213  * Wait for an incoming connection, avoid race conditions. This must be called
214  * with the socket locked.
215  */
216 static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
217 {
218 	struct inet_connection_sock *icsk = inet_csk(sk);
219 	DEFINE_WAIT(wait);
220 	int err;
221 
222 	/*
223 	 * True wake-one mechanism for incoming connections: only
224 	 * one process gets woken up, not the 'whole herd'.
225 	 * Since we do not 'race & poll' for established sockets
226 	 * anymore, the common case will execute the loop only once.
227 	 *
228 	 * Subtle issue: "add_wait_queue_exclusive()" will be added
229 	 * after any current non-exclusive waiters, and we know that
230 	 * it will always _stay_ after any new non-exclusive waiters
231 	 * because all non-exclusive waiters are added at the
232 	 * beginning of the wait-queue. As such, it's ok to "drop"
233 	 * our exclusiveness temporarily when we get woken up without
234 	 * having to remove and re-insert us on the wait queue.
235 	 */
236 	for (;;) {
237 		prepare_to_wait_exclusive(sk->sk_sleep, &wait,
238 					  TASK_INTERRUPTIBLE);
239 		release_sock(sk);
240 		if (reqsk_queue_empty(&icsk->icsk_accept_queue))
241 			timeo = schedule_timeout(timeo);
242 		lock_sock(sk);
243 		err = 0;
244 		if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
245 			break;
246 		err = -EINVAL;
247 		if (sk->sk_state != TCP_LISTEN)
248 			break;
249 		err = sock_intr_errno(timeo);
250 		if (signal_pending(current))
251 			break;
252 		err = -EAGAIN;
253 		if (!timeo)
254 			break;
255 	}
256 	finish_wait(sk->sk_sleep, &wait);
257 	return err;
258 }
259 
260 /*
261  * This will accept the next outstanding connection.
262  */
263 struct sock *inet_csk_accept(struct sock *sk, int flags, int *err)
264 {
265 	struct inet_connection_sock *icsk = inet_csk(sk);
266 	struct sock *newsk;
267 	int error;
268 
269 	lock_sock(sk);
270 
271 	/* We need to make sure that this socket is listening,
272 	 * and that it has something pending.
273 	 */
274 	error = -EINVAL;
275 	if (sk->sk_state != TCP_LISTEN)
276 		goto out_err;
277 
278 	/* Find already established connection */
279 	if (reqsk_queue_empty(&icsk->icsk_accept_queue)) {
280 		long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
281 
282 		/* If this is a non blocking socket don't sleep */
283 		error = -EAGAIN;
284 		if (!timeo)
285 			goto out_err;
286 
287 		error = inet_csk_wait_for_connect(sk, timeo);
288 		if (error)
289 			goto out_err;
290 	}
291 
292 	newsk = reqsk_queue_get_child(&icsk->icsk_accept_queue, sk);
293 	WARN_ON(newsk->sk_state == TCP_SYN_RECV);
294 out:
295 	release_sock(sk);
296 	return newsk;
297 out_err:
298 	newsk = NULL;
299 	*err = error;
300 	goto out;
301 }
302 
303 EXPORT_SYMBOL(inet_csk_accept);
304 
305 /*
306  * Using different timers for retransmit, delayed acks and probes
307  * We may wish use just one timer maintaining a list of expire jiffies
308  * to optimize.
309  */
310 void inet_csk_init_xmit_timers(struct sock *sk,
311 			       void (*retransmit_handler)(unsigned long),
312 			       void (*delack_handler)(unsigned long),
313 			       void (*keepalive_handler)(unsigned long))
314 {
315 	struct inet_connection_sock *icsk = inet_csk(sk);
316 
317 	setup_timer(&icsk->icsk_retransmit_timer, retransmit_handler,
318 			(unsigned long)sk);
319 	setup_timer(&icsk->icsk_delack_timer, delack_handler,
320 			(unsigned long)sk);
321 	setup_timer(&sk->sk_timer, keepalive_handler, (unsigned long)sk);
322 	icsk->icsk_pending = icsk->icsk_ack.pending = 0;
323 }
324 
325 EXPORT_SYMBOL(inet_csk_init_xmit_timers);
326 
327 void inet_csk_clear_xmit_timers(struct sock *sk)
328 {
329 	struct inet_connection_sock *icsk = inet_csk(sk);
330 
331 	icsk->icsk_pending = icsk->icsk_ack.pending = icsk->icsk_ack.blocked = 0;
332 
333 	sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
334 	sk_stop_timer(sk, &icsk->icsk_delack_timer);
335 	sk_stop_timer(sk, &sk->sk_timer);
336 }
337 
338 EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
339 
340 void inet_csk_delete_keepalive_timer(struct sock *sk)
341 {
342 	sk_stop_timer(sk, &sk->sk_timer);
343 }
344 
345 EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
346 
347 void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
348 {
349 	sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
350 }
351 
352 EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
353 
354 struct dst_entry *inet_csk_route_req(struct sock *sk,
355 				     const struct request_sock *req)
356 {
357 	struct rtable *rt;
358 	const struct inet_request_sock *ireq = inet_rsk(req);
359 	struct ip_options *opt = inet_rsk(req)->opt;
360 	struct flowi fl = { .oif = sk->sk_bound_dev_if,
361 			    .mark = sk->sk_mark,
362 			    .nl_u = { .ip4_u =
363 				      { .daddr = ((opt && opt->srr) ?
364 						  opt->faddr :
365 						  ireq->rmt_addr),
366 					.saddr = ireq->loc_addr,
367 					.tos = RT_CONN_FLAGS(sk) } },
368 			    .proto = sk->sk_protocol,
369 			    .flags = inet_sk_flowi_flags(sk),
370 			    .uli_u = { .ports =
371 				       { .sport = inet_sk(sk)->inet_sport,
372 					 .dport = ireq->rmt_port } } };
373 	struct net *net = sock_net(sk);
374 
375 	security_req_classify_flow(req, &fl);
376 	if (ip_route_output_flow(net, &rt, &fl, sk, 0))
377 		goto no_route;
378 	if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway)
379 		goto route_err;
380 	return &rt->u.dst;
381 
382 route_err:
383 	ip_rt_put(rt);
384 no_route:
385 	IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES);
386 	return NULL;
387 }
388 
389 EXPORT_SYMBOL_GPL(inet_csk_route_req);
390 
391 static inline u32 inet_synq_hash(const __be32 raddr, const __be16 rport,
392 				 const u32 rnd, const u32 synq_hsize)
393 {
394 	return jhash_2words((__force u32)raddr, (__force u32)rport, rnd) & (synq_hsize - 1);
395 }
396 
397 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
398 #define AF_INET_FAMILY(fam) ((fam) == AF_INET)
399 #else
400 #define AF_INET_FAMILY(fam) 1
401 #endif
402 
403 struct request_sock *inet_csk_search_req(const struct sock *sk,
404 					 struct request_sock ***prevp,
405 					 const __be16 rport, const __be32 raddr,
406 					 const __be32 laddr)
407 {
408 	const struct inet_connection_sock *icsk = inet_csk(sk);
409 	struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
410 	struct request_sock *req, **prev;
411 
412 	for (prev = &lopt->syn_table[inet_synq_hash(raddr, rport, lopt->hash_rnd,
413 						    lopt->nr_table_entries)];
414 	     (req = *prev) != NULL;
415 	     prev = &req->dl_next) {
416 		const struct inet_request_sock *ireq = inet_rsk(req);
417 
418 		if (ireq->rmt_port == rport &&
419 		    ireq->rmt_addr == raddr &&
420 		    ireq->loc_addr == laddr &&
421 		    AF_INET_FAMILY(req->rsk_ops->family)) {
422 			WARN_ON(req->sk);
423 			*prevp = prev;
424 			break;
425 		}
426 	}
427 
428 	return req;
429 }
430 
431 EXPORT_SYMBOL_GPL(inet_csk_search_req);
432 
433 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
434 				   unsigned long timeout)
435 {
436 	struct inet_connection_sock *icsk = inet_csk(sk);
437 	struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
438 	const u32 h = inet_synq_hash(inet_rsk(req)->rmt_addr, inet_rsk(req)->rmt_port,
439 				     lopt->hash_rnd, lopt->nr_table_entries);
440 
441 	reqsk_queue_hash_req(&icsk->icsk_accept_queue, h, req, timeout);
442 	inet_csk_reqsk_queue_added(sk, timeout);
443 }
444 
445 /* Only thing we need from tcp.h */
446 extern int sysctl_tcp_synack_retries;
447 
448 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
449 
450 /* Decide when to expire the request and when to resend SYN-ACK */
451 static inline void syn_ack_recalc(struct request_sock *req, const int thresh,
452 				  const int max_retries,
453 				  const u8 rskq_defer_accept,
454 				  int *expire, int *resend)
455 {
456 	if (!rskq_defer_accept) {
457 		*expire = req->retrans >= thresh;
458 		*resend = 1;
459 		return;
460 	}
461 	*expire = req->retrans >= thresh &&
462 		  (!inet_rsk(req)->acked || req->retrans >= max_retries);
463 	/*
464 	 * Do not resend while waiting for data after ACK,
465 	 * start to resend on end of deferring period to give
466 	 * last chance for data or ACK to create established socket.
467 	 */
468 	*resend = !inet_rsk(req)->acked ||
469 		  req->retrans >= rskq_defer_accept - 1;
470 }
471 
472 void inet_csk_reqsk_queue_prune(struct sock *parent,
473 				const unsigned long interval,
474 				const unsigned long timeout,
475 				const unsigned long max_rto)
476 {
477 	struct inet_connection_sock *icsk = inet_csk(parent);
478 	struct request_sock_queue *queue = &icsk->icsk_accept_queue;
479 	struct listen_sock *lopt = queue->listen_opt;
480 	int max_retries = icsk->icsk_syn_retries ? : sysctl_tcp_synack_retries;
481 	int thresh = max_retries;
482 	unsigned long now = jiffies;
483 	struct request_sock **reqp, *req;
484 	int i, budget;
485 
486 	if (lopt == NULL || lopt->qlen == 0)
487 		return;
488 
489 	/* Normally all the openreqs are young and become mature
490 	 * (i.e. converted to established socket) for first timeout.
491 	 * If synack was not acknowledged for 3 seconds, it means
492 	 * one of the following things: synack was lost, ack was lost,
493 	 * rtt is high or nobody planned to ack (i.e. synflood).
494 	 * When server is a bit loaded, queue is populated with old
495 	 * open requests, reducing effective size of queue.
496 	 * When server is well loaded, queue size reduces to zero
497 	 * after several minutes of work. It is not synflood,
498 	 * it is normal operation. The solution is pruning
499 	 * too old entries overriding normal timeout, when
500 	 * situation becomes dangerous.
501 	 *
502 	 * Essentially, we reserve half of room for young
503 	 * embrions; and abort old ones without pity, if old
504 	 * ones are about to clog our table.
505 	 */
506 	if (lopt->qlen>>(lopt->max_qlen_log-1)) {
507 		int young = (lopt->qlen_young<<1);
508 
509 		while (thresh > 2) {
510 			if (lopt->qlen < young)
511 				break;
512 			thresh--;
513 			young <<= 1;
514 		}
515 	}
516 
517 	if (queue->rskq_defer_accept)
518 		max_retries = queue->rskq_defer_accept;
519 
520 	budget = 2 * (lopt->nr_table_entries / (timeout / interval));
521 	i = lopt->clock_hand;
522 
523 	do {
524 		reqp=&lopt->syn_table[i];
525 		while ((req = *reqp) != NULL) {
526 			if (time_after_eq(now, req->expires)) {
527 				int expire = 0, resend = 0;
528 
529 				syn_ack_recalc(req, thresh, max_retries,
530 					       queue->rskq_defer_accept,
531 					       &expire, &resend);
532 				if (!expire &&
533 				    (!resend ||
534 				     !req->rsk_ops->rtx_syn_ack(parent, req, NULL) ||
535 				     inet_rsk(req)->acked)) {
536 					unsigned long timeo;
537 
538 					if (req->retrans++ == 0)
539 						lopt->qlen_young--;
540 					timeo = min((timeout << req->retrans), max_rto);
541 					req->expires = now + timeo;
542 					reqp = &req->dl_next;
543 					continue;
544 				}
545 
546 				/* Drop this request */
547 				inet_csk_reqsk_queue_unlink(parent, req, reqp);
548 				reqsk_queue_removed(queue, req);
549 				reqsk_free(req);
550 				continue;
551 			}
552 			reqp = &req->dl_next;
553 		}
554 
555 		i = (i + 1) & (lopt->nr_table_entries - 1);
556 
557 	} while (--budget > 0);
558 
559 	lopt->clock_hand = i;
560 
561 	if (lopt->qlen)
562 		inet_csk_reset_keepalive_timer(parent, interval);
563 }
564 
565 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_prune);
566 
567 struct sock *inet_csk_clone(struct sock *sk, const struct request_sock *req,
568 			    const gfp_t priority)
569 {
570 	struct sock *newsk = sk_clone(sk, priority);
571 
572 	if (newsk != NULL) {
573 		struct inet_connection_sock *newicsk = inet_csk(newsk);
574 
575 		newsk->sk_state = TCP_SYN_RECV;
576 		newicsk->icsk_bind_hash = NULL;
577 
578 		inet_sk(newsk)->inet_dport = inet_rsk(req)->rmt_port;
579 		inet_sk(newsk)->inet_num = ntohs(inet_rsk(req)->loc_port);
580 		inet_sk(newsk)->inet_sport = inet_rsk(req)->loc_port;
581 		newsk->sk_write_space = sk_stream_write_space;
582 
583 		newicsk->icsk_retransmits = 0;
584 		newicsk->icsk_backoff	  = 0;
585 		newicsk->icsk_probes_out  = 0;
586 
587 		/* Deinitialize accept_queue to trap illegal accesses. */
588 		memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
589 
590 		security_inet_csk_clone(newsk, req);
591 	}
592 	return newsk;
593 }
594 
595 EXPORT_SYMBOL_GPL(inet_csk_clone);
596 
597 /*
598  * At this point, there should be no process reference to this
599  * socket, and thus no user references at all.  Therefore we
600  * can assume the socket waitqueue is inactive and nobody will
601  * try to jump onto it.
602  */
603 void inet_csk_destroy_sock(struct sock *sk)
604 {
605 	WARN_ON(sk->sk_state != TCP_CLOSE);
606 	WARN_ON(!sock_flag(sk, SOCK_DEAD));
607 
608 	/* It cannot be in hash table! */
609 	WARN_ON(!sk_unhashed(sk));
610 
611 	/* If it has not 0 inet_sk(sk)->inet_num, it must be bound */
612 	WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash);
613 
614 	sk->sk_prot->destroy(sk);
615 
616 	sk_stream_kill_queues(sk);
617 
618 	xfrm_sk_free_policy(sk);
619 
620 	sk_refcnt_debug_release(sk);
621 
622 	percpu_counter_dec(sk->sk_prot->orphan_count);
623 	sock_put(sk);
624 }
625 
626 EXPORT_SYMBOL(inet_csk_destroy_sock);
627 
628 int inet_csk_listen_start(struct sock *sk, const int nr_table_entries)
629 {
630 	struct inet_sock *inet = inet_sk(sk);
631 	struct inet_connection_sock *icsk = inet_csk(sk);
632 	int rc = reqsk_queue_alloc(&icsk->icsk_accept_queue, nr_table_entries);
633 
634 	if (rc != 0)
635 		return rc;
636 
637 	sk->sk_max_ack_backlog = 0;
638 	sk->sk_ack_backlog = 0;
639 	inet_csk_delack_init(sk);
640 
641 	/* There is race window here: we announce ourselves listening,
642 	 * but this transition is still not validated by get_port().
643 	 * It is OK, because this socket enters to hash table only
644 	 * after validation is complete.
645 	 */
646 	sk->sk_state = TCP_LISTEN;
647 	if (!sk->sk_prot->get_port(sk, inet->inet_num)) {
648 		inet->inet_sport = htons(inet->inet_num);
649 
650 		sk_dst_reset(sk);
651 		sk->sk_prot->hash(sk);
652 
653 		return 0;
654 	}
655 
656 	sk->sk_state = TCP_CLOSE;
657 	__reqsk_queue_destroy(&icsk->icsk_accept_queue);
658 	return -EADDRINUSE;
659 }
660 
661 EXPORT_SYMBOL_GPL(inet_csk_listen_start);
662 
663 /*
664  *	This routine closes sockets which have been at least partially
665  *	opened, but not yet accepted.
666  */
667 void inet_csk_listen_stop(struct sock *sk)
668 {
669 	struct inet_connection_sock *icsk = inet_csk(sk);
670 	struct request_sock *acc_req;
671 	struct request_sock *req;
672 
673 	inet_csk_delete_keepalive_timer(sk);
674 
675 	/* make all the listen_opt local to us */
676 	acc_req = reqsk_queue_yank_acceptq(&icsk->icsk_accept_queue);
677 
678 	/* Following specs, it would be better either to send FIN
679 	 * (and enter FIN-WAIT-1, it is normal close)
680 	 * or to send active reset (abort).
681 	 * Certainly, it is pretty dangerous while synflood, but it is
682 	 * bad justification for our negligence 8)
683 	 * To be honest, we are not able to make either
684 	 * of the variants now.			--ANK
685 	 */
686 	reqsk_queue_destroy(&icsk->icsk_accept_queue);
687 
688 	while ((req = acc_req) != NULL) {
689 		struct sock *child = req->sk;
690 
691 		acc_req = req->dl_next;
692 
693 		local_bh_disable();
694 		bh_lock_sock(child);
695 		WARN_ON(sock_owned_by_user(child));
696 		sock_hold(child);
697 
698 		sk->sk_prot->disconnect(child, O_NONBLOCK);
699 
700 		sock_orphan(child);
701 
702 		percpu_counter_inc(sk->sk_prot->orphan_count);
703 
704 		inet_csk_destroy_sock(child);
705 
706 		bh_unlock_sock(child);
707 		local_bh_enable();
708 		sock_put(child);
709 
710 		sk_acceptq_removed(sk);
711 		__reqsk_free(req);
712 	}
713 	WARN_ON(sk->sk_ack_backlog);
714 }
715 
716 EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
717 
718 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
719 {
720 	struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
721 	const struct inet_sock *inet = inet_sk(sk);
722 
723 	sin->sin_family		= AF_INET;
724 	sin->sin_addr.s_addr	= inet->inet_daddr;
725 	sin->sin_port		= inet->inet_dport;
726 }
727 
728 EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);
729 
730 #ifdef CONFIG_COMPAT
731 int inet_csk_compat_getsockopt(struct sock *sk, int level, int optname,
732 			       char __user *optval, int __user *optlen)
733 {
734 	const struct inet_connection_sock *icsk = inet_csk(sk);
735 
736 	if (icsk->icsk_af_ops->compat_getsockopt != NULL)
737 		return icsk->icsk_af_ops->compat_getsockopt(sk, level, optname,
738 							    optval, optlen);
739 	return icsk->icsk_af_ops->getsockopt(sk, level, optname,
740 					     optval, optlen);
741 }
742 
743 EXPORT_SYMBOL_GPL(inet_csk_compat_getsockopt);
744 
745 int inet_csk_compat_setsockopt(struct sock *sk, int level, int optname,
746 			       char __user *optval, unsigned int optlen)
747 {
748 	const struct inet_connection_sock *icsk = inet_csk(sk);
749 
750 	if (icsk->icsk_af_ops->compat_setsockopt != NULL)
751 		return icsk->icsk_af_ops->compat_setsockopt(sk, level, optname,
752 							    optval, optlen);
753 	return icsk->icsk_af_ops->setsockopt(sk, level, optname,
754 					     optval, optlen);
755 }
756 
757 EXPORT_SYMBOL_GPL(inet_csk_compat_setsockopt);
758 #endif
759