xref: /linux/net/ipv4/inet_connection_sock.c (revision f850548ef88e5ff9e40bae9e1a7140bef0653e6b)
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 unsigned long *sysctl_local_reserved_ports;
41 EXPORT_SYMBOL(sysctl_local_reserved_ports);
42 
43 void inet_get_local_port_range(int *low, int *high)
44 {
45 	unsigned seq;
46 	do {
47 		seq = read_seqbegin(&sysctl_local_ports.lock);
48 
49 		*low = sysctl_local_ports.range[0];
50 		*high = sysctl_local_ports.range[1];
51 	} while (read_seqretry(&sysctl_local_ports.lock, seq));
52 }
53 EXPORT_SYMBOL(inet_get_local_port_range);
54 
55 int inet_csk_bind_conflict(const struct sock *sk,
56 			   const struct inet_bind_bucket *tb)
57 {
58 	struct sock *sk2;
59 	struct hlist_node *node;
60 	int reuse = sk->sk_reuse;
61 
62 	/*
63 	 * Unlike other sk lookup places we do not check
64 	 * for sk_net here, since _all_ the socks listed
65 	 * in tb->owners list belong to the same net - the
66 	 * one this bucket belongs to.
67 	 */
68 
69 	sk_for_each_bound(sk2, node, &tb->owners) {
70 		if (sk != sk2 &&
71 		    !inet_v6_ipv6only(sk2) &&
72 		    (!sk->sk_bound_dev_if ||
73 		     !sk2->sk_bound_dev_if ||
74 		     sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
75 			if (!reuse || !sk2->sk_reuse ||
76 			    sk2->sk_state == TCP_LISTEN) {
77 				const __be32 sk2_rcv_saddr = sk_rcv_saddr(sk2);
78 				if (!sk2_rcv_saddr || !sk_rcv_saddr(sk) ||
79 				    sk2_rcv_saddr == sk_rcv_saddr(sk))
80 					break;
81 			}
82 		}
83 	}
84 	return node != NULL;
85 }
86 EXPORT_SYMBOL_GPL(inet_csk_bind_conflict);
87 
88 /* Obtain a reference to a local port for the given sock,
89  * if snum is zero it means select any available local port.
90  */
91 int inet_csk_get_port(struct sock *sk, unsigned short snum)
92 {
93 	struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
94 	struct inet_bind_hashbucket *head;
95 	struct hlist_node *node;
96 	struct inet_bind_bucket *tb;
97 	int ret, attempts = 5;
98 	struct net *net = sock_net(sk);
99 	int smallest_size = -1, smallest_rover;
100 
101 	local_bh_disable();
102 	if (!snum) {
103 		int remaining, rover, low, high;
104 
105 again:
106 		inet_get_local_port_range(&low, &high);
107 		remaining = (high - low) + 1;
108 		smallest_rover = rover = net_random() % remaining + low;
109 
110 		smallest_size = -1;
111 		do {
112 			if (inet_is_reserved_local_port(rover))
113 				goto next_nolock;
114 			head = &hashinfo->bhash[inet_bhashfn(net, rover,
115 					hashinfo->bhash_size)];
116 			spin_lock(&head->lock);
117 			inet_bind_bucket_for_each(tb, node, &head->chain)
118 				if (net_eq(ib_net(tb), net) && tb->port == rover) {
119 					if (tb->fastreuse > 0 &&
120 					    sk->sk_reuse &&
121 					    sk->sk_state != TCP_LISTEN &&
122 					    (tb->num_owners < smallest_size || smallest_size == -1)) {
123 						smallest_size = tb->num_owners;
124 						smallest_rover = rover;
125 						if (atomic_read(&hashinfo->bsockets) > (high - low) + 1) {
126 							spin_unlock(&head->lock);
127 							snum = smallest_rover;
128 							goto have_snum;
129 						}
130 					}
131 					goto next;
132 				}
133 			break;
134 		next:
135 			spin_unlock(&head->lock);
136 		next_nolock:
137 			if (++rover > high)
138 				rover = low;
139 		} while (--remaining > 0);
140 
141 		/* Exhausted local port range during search?  It is not
142 		 * possible for us to be holding one of the bind hash
143 		 * locks if this test triggers, because if 'remaining'
144 		 * drops to zero, we broke out of the do/while loop at
145 		 * the top level, not from the 'break;' statement.
146 		 */
147 		ret = 1;
148 		if (remaining <= 0) {
149 			if (smallest_size != -1) {
150 				snum = smallest_rover;
151 				goto have_snum;
152 			}
153 			goto fail;
154 		}
155 		/* OK, here is the one we will use.  HEAD is
156 		 * non-NULL and we hold it's mutex.
157 		 */
158 		snum = rover;
159 	} else {
160 have_snum:
161 		head = &hashinfo->bhash[inet_bhashfn(net, snum,
162 				hashinfo->bhash_size)];
163 		spin_lock(&head->lock);
164 		inet_bind_bucket_for_each(tb, node, &head->chain)
165 			if (net_eq(ib_net(tb), net) && tb->port == snum)
166 				goto tb_found;
167 	}
168 	tb = NULL;
169 	goto tb_not_found;
170 tb_found:
171 	if (!hlist_empty(&tb->owners)) {
172 		if (tb->fastreuse > 0 &&
173 		    sk->sk_reuse && sk->sk_state != TCP_LISTEN &&
174 		    smallest_size == -1) {
175 			goto success;
176 		} else {
177 			ret = 1;
178 			if (inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb)) {
179 				if (sk->sk_reuse && sk->sk_state != TCP_LISTEN &&
180 				    smallest_size != -1 && --attempts >= 0) {
181 					spin_unlock(&head->lock);
182 					goto again;
183 				}
184 				goto fail_unlock;
185 			}
186 		}
187 	}
188 tb_not_found:
189 	ret = 1;
190 	if (!tb && (tb = inet_bind_bucket_create(hashinfo->bind_bucket_cachep,
191 					net, head, snum)) == NULL)
192 		goto fail_unlock;
193 	if (hlist_empty(&tb->owners)) {
194 		if (sk->sk_reuse && sk->sk_state != TCP_LISTEN)
195 			tb->fastreuse = 1;
196 		else
197 			tb->fastreuse = 0;
198 	} else if (tb->fastreuse &&
199 		   (!sk->sk_reuse || sk->sk_state == TCP_LISTEN))
200 		tb->fastreuse = 0;
201 success:
202 	if (!inet_csk(sk)->icsk_bind_hash)
203 		inet_bind_hash(sk, tb, snum);
204 	WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);
205 	ret = 0;
206 
207 fail_unlock:
208 	spin_unlock(&head->lock);
209 fail:
210 	local_bh_enable();
211 	return ret;
212 }
213 EXPORT_SYMBOL_GPL(inet_csk_get_port);
214 
215 /*
216  * Wait for an incoming connection, avoid race conditions. This must be called
217  * with the socket locked.
218  */
219 static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
220 {
221 	struct inet_connection_sock *icsk = inet_csk(sk);
222 	DEFINE_WAIT(wait);
223 	int err;
224 
225 	/*
226 	 * True wake-one mechanism for incoming connections: only
227 	 * one process gets woken up, not the 'whole herd'.
228 	 * Since we do not 'race & poll' for established sockets
229 	 * anymore, the common case will execute the loop only once.
230 	 *
231 	 * Subtle issue: "add_wait_queue_exclusive()" will be added
232 	 * after any current non-exclusive waiters, and we know that
233 	 * it will always _stay_ after any new non-exclusive waiters
234 	 * because all non-exclusive waiters are added at the
235 	 * beginning of the wait-queue. As such, it's ok to "drop"
236 	 * our exclusiveness temporarily when we get woken up without
237 	 * having to remove and re-insert us on the wait queue.
238 	 */
239 	for (;;) {
240 		prepare_to_wait_exclusive(sk_sleep(sk), &wait,
241 					  TASK_INTERRUPTIBLE);
242 		release_sock(sk);
243 		if (reqsk_queue_empty(&icsk->icsk_accept_queue))
244 			timeo = schedule_timeout(timeo);
245 		lock_sock(sk);
246 		err = 0;
247 		if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
248 			break;
249 		err = -EINVAL;
250 		if (sk->sk_state != TCP_LISTEN)
251 			break;
252 		err = sock_intr_errno(timeo);
253 		if (signal_pending(current))
254 			break;
255 		err = -EAGAIN;
256 		if (!timeo)
257 			break;
258 	}
259 	finish_wait(sk_sleep(sk), &wait);
260 	return err;
261 }
262 
263 /*
264  * This will accept the next outstanding connection.
265  */
266 struct sock *inet_csk_accept(struct sock *sk, int flags, int *err)
267 {
268 	struct inet_connection_sock *icsk = inet_csk(sk);
269 	struct sock *newsk;
270 	int error;
271 
272 	lock_sock(sk);
273 
274 	/* We need to make sure that this socket is listening,
275 	 * and that it has something pending.
276 	 */
277 	error = -EINVAL;
278 	if (sk->sk_state != TCP_LISTEN)
279 		goto out_err;
280 
281 	/* Find already established connection */
282 	if (reqsk_queue_empty(&icsk->icsk_accept_queue)) {
283 		long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
284 
285 		/* If this is a non blocking socket don't sleep */
286 		error = -EAGAIN;
287 		if (!timeo)
288 			goto out_err;
289 
290 		error = inet_csk_wait_for_connect(sk, timeo);
291 		if (error)
292 			goto out_err;
293 	}
294 
295 	newsk = reqsk_queue_get_child(&icsk->icsk_accept_queue, sk);
296 	WARN_ON(newsk->sk_state == TCP_SYN_RECV);
297 out:
298 	release_sock(sk);
299 	return newsk;
300 out_err:
301 	newsk = NULL;
302 	*err = error;
303 	goto out;
304 }
305 EXPORT_SYMBOL(inet_csk_accept);
306 
307 /*
308  * Using different timers for retransmit, delayed acks and probes
309  * We may wish use just one timer maintaining a list of expire jiffies
310  * to optimize.
311  */
312 void inet_csk_init_xmit_timers(struct sock *sk,
313 			       void (*retransmit_handler)(unsigned long),
314 			       void (*delack_handler)(unsigned long),
315 			       void (*keepalive_handler)(unsigned long))
316 {
317 	struct inet_connection_sock *icsk = inet_csk(sk);
318 
319 	setup_timer(&icsk->icsk_retransmit_timer, retransmit_handler,
320 			(unsigned long)sk);
321 	setup_timer(&icsk->icsk_delack_timer, delack_handler,
322 			(unsigned long)sk);
323 	setup_timer(&sk->sk_timer, keepalive_handler, (unsigned long)sk);
324 	icsk->icsk_pending = icsk->icsk_ack.pending = 0;
325 }
326 EXPORT_SYMBOL(inet_csk_init_xmit_timers);
327 
328 void inet_csk_clear_xmit_timers(struct sock *sk)
329 {
330 	struct inet_connection_sock *icsk = inet_csk(sk);
331 
332 	icsk->icsk_pending = icsk->icsk_ack.pending = icsk->icsk_ack.blocked = 0;
333 
334 	sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
335 	sk_stop_timer(sk, &icsk->icsk_delack_timer);
336 	sk_stop_timer(sk, &sk->sk_timer);
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 EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
345 
346 void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
347 {
348 	sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
349 }
350 EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
351 
352 struct dst_entry *inet_csk_route_req(struct sock *sk,
353 				     const struct request_sock *req)
354 {
355 	struct rtable *rt;
356 	const struct inet_request_sock *ireq = inet_rsk(req);
357 	struct ip_options *opt = inet_rsk(req)->opt;
358 	struct flowi4 fl4 = {
359 		.flowi4_oif = sk->sk_bound_dev_if,
360 		.flowi4_mark = sk->sk_mark,
361 		.daddr = ((opt && opt->srr) ?
362 			  opt->faddr : ireq->rmt_addr),
363 		.saddr = ireq->loc_addr,
364 		.flowi4_tos = RT_CONN_FLAGS(sk),
365 		.flowi4_proto = sk->sk_protocol,
366 		.flowi4_flags = inet_sk_flowi_flags(sk),
367 		.fl4_sport = inet_sk(sk)->inet_sport,
368 		.fl4_dport = ireq->rmt_port,
369 	};
370 	struct net *net = sock_net(sk);
371 
372 	security_req_classify_flow(req, flowi4_to_flowi(&fl4));
373 	rt = ip_route_output_flow(net, &fl4, sk);
374 	if (IS_ERR(rt))
375 		goto no_route;
376 	if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway)
377 		goto route_err;
378 	return &rt->dst;
379 
380 route_err:
381 	ip_rt_put(rt);
382 no_route:
383 	IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES);
384 	return NULL;
385 }
386 EXPORT_SYMBOL_GPL(inet_csk_route_req);
387 
388 static inline u32 inet_synq_hash(const __be32 raddr, const __be16 rport,
389 				 const u32 rnd, const u32 synq_hsize)
390 {
391 	return jhash_2words((__force u32)raddr, (__force u32)rport, rnd) & (synq_hsize - 1);
392 }
393 
394 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
395 #define AF_INET_FAMILY(fam) ((fam) == AF_INET)
396 #else
397 #define AF_INET_FAMILY(fam) 1
398 #endif
399 
400 struct request_sock *inet_csk_search_req(const struct sock *sk,
401 					 struct request_sock ***prevp,
402 					 const __be16 rport, const __be32 raddr,
403 					 const __be32 laddr)
404 {
405 	const struct inet_connection_sock *icsk = inet_csk(sk);
406 	struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
407 	struct request_sock *req, **prev;
408 
409 	for (prev = &lopt->syn_table[inet_synq_hash(raddr, rport, lopt->hash_rnd,
410 						    lopt->nr_table_entries)];
411 	     (req = *prev) != NULL;
412 	     prev = &req->dl_next) {
413 		const struct inet_request_sock *ireq = inet_rsk(req);
414 
415 		if (ireq->rmt_port == rport &&
416 		    ireq->rmt_addr == raddr &&
417 		    ireq->loc_addr == laddr &&
418 		    AF_INET_FAMILY(req->rsk_ops->family)) {
419 			WARN_ON(req->sk);
420 			*prevp = prev;
421 			break;
422 		}
423 	}
424 
425 	return req;
426 }
427 EXPORT_SYMBOL_GPL(inet_csk_search_req);
428 
429 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
430 				   unsigned long timeout)
431 {
432 	struct inet_connection_sock *icsk = inet_csk(sk);
433 	struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
434 	const u32 h = inet_synq_hash(inet_rsk(req)->rmt_addr, inet_rsk(req)->rmt_port,
435 				     lopt->hash_rnd, lopt->nr_table_entries);
436 
437 	reqsk_queue_hash_req(&icsk->icsk_accept_queue, h, req, timeout);
438 	inet_csk_reqsk_queue_added(sk, timeout);
439 }
440 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
441 
442 /* Only thing we need from tcp.h */
443 extern int sysctl_tcp_synack_retries;
444 
445 
446 /* Decide when to expire the request and when to resend SYN-ACK */
447 static inline void syn_ack_recalc(struct request_sock *req, const int thresh,
448 				  const int max_retries,
449 				  const u8 rskq_defer_accept,
450 				  int *expire, int *resend)
451 {
452 	if (!rskq_defer_accept) {
453 		*expire = req->retrans >= thresh;
454 		*resend = 1;
455 		return;
456 	}
457 	*expire = req->retrans >= thresh &&
458 		  (!inet_rsk(req)->acked || req->retrans >= max_retries);
459 	/*
460 	 * Do not resend while waiting for data after ACK,
461 	 * start to resend on end of deferring period to give
462 	 * last chance for data or ACK to create established socket.
463 	 */
464 	*resend = !inet_rsk(req)->acked ||
465 		  req->retrans >= rskq_defer_accept - 1;
466 }
467 
468 void inet_csk_reqsk_queue_prune(struct sock *parent,
469 				const unsigned long interval,
470 				const unsigned long timeout,
471 				const unsigned long max_rto)
472 {
473 	struct inet_connection_sock *icsk = inet_csk(parent);
474 	struct request_sock_queue *queue = &icsk->icsk_accept_queue;
475 	struct listen_sock *lopt = queue->listen_opt;
476 	int max_retries = icsk->icsk_syn_retries ? : sysctl_tcp_synack_retries;
477 	int thresh = max_retries;
478 	unsigned long now = jiffies;
479 	struct request_sock **reqp, *req;
480 	int i, budget;
481 
482 	if (lopt == NULL || lopt->qlen == 0)
483 		return;
484 
485 	/* Normally all the openreqs are young and become mature
486 	 * (i.e. converted to established socket) for first timeout.
487 	 * If synack was not acknowledged for 3 seconds, it means
488 	 * one of the following things: synack was lost, ack was lost,
489 	 * rtt is high or nobody planned to ack (i.e. synflood).
490 	 * When server is a bit loaded, queue is populated with old
491 	 * open requests, reducing effective size of queue.
492 	 * When server is well loaded, queue size reduces to zero
493 	 * after several minutes of work. It is not synflood,
494 	 * it is normal operation. The solution is pruning
495 	 * too old entries overriding normal timeout, when
496 	 * situation becomes dangerous.
497 	 *
498 	 * Essentially, we reserve half of room for young
499 	 * embrions; and abort old ones without pity, if old
500 	 * ones are about to clog our table.
501 	 */
502 	if (lopt->qlen>>(lopt->max_qlen_log-1)) {
503 		int young = (lopt->qlen_young<<1);
504 
505 		while (thresh > 2) {
506 			if (lopt->qlen < young)
507 				break;
508 			thresh--;
509 			young <<= 1;
510 		}
511 	}
512 
513 	if (queue->rskq_defer_accept)
514 		max_retries = queue->rskq_defer_accept;
515 
516 	budget = 2 * (lopt->nr_table_entries / (timeout / interval));
517 	i = lopt->clock_hand;
518 
519 	do {
520 		reqp=&lopt->syn_table[i];
521 		while ((req = *reqp) != NULL) {
522 			if (time_after_eq(now, req->expires)) {
523 				int expire = 0, resend = 0;
524 
525 				syn_ack_recalc(req, thresh, max_retries,
526 					       queue->rskq_defer_accept,
527 					       &expire, &resend);
528 				if (req->rsk_ops->syn_ack_timeout)
529 					req->rsk_ops->syn_ack_timeout(parent, req);
530 				if (!expire &&
531 				    (!resend ||
532 				     !req->rsk_ops->rtx_syn_ack(parent, req, NULL) ||
533 				     inet_rsk(req)->acked)) {
534 					unsigned long timeo;
535 
536 					if (req->retrans++ == 0)
537 						lopt->qlen_young--;
538 					timeo = min((timeout << req->retrans), max_rto);
539 					req->expires = now + timeo;
540 					reqp = &req->dl_next;
541 					continue;
542 				}
543 
544 				/* Drop this request */
545 				inet_csk_reqsk_queue_unlink(parent, req, reqp);
546 				reqsk_queue_removed(queue, req);
547 				reqsk_free(req);
548 				continue;
549 			}
550 			reqp = &req->dl_next;
551 		}
552 
553 		i = (i + 1) & (lopt->nr_table_entries - 1);
554 
555 	} while (--budget > 0);
556 
557 	lopt->clock_hand = i;
558 
559 	if (lopt->qlen)
560 		inet_csk_reset_keepalive_timer(parent, interval);
561 }
562 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_prune);
563 
564 struct sock *inet_csk_clone(struct sock *sk, const struct request_sock *req,
565 			    const gfp_t priority)
566 {
567 	struct sock *newsk = sk_clone(sk, priority);
568 
569 	if (newsk != NULL) {
570 		struct inet_connection_sock *newicsk = inet_csk(newsk);
571 
572 		newsk->sk_state = TCP_SYN_RECV;
573 		newicsk->icsk_bind_hash = NULL;
574 
575 		inet_sk(newsk)->inet_dport = inet_rsk(req)->rmt_port;
576 		inet_sk(newsk)->inet_num = ntohs(inet_rsk(req)->loc_port);
577 		inet_sk(newsk)->inet_sport = inet_rsk(req)->loc_port;
578 		newsk->sk_write_space = sk_stream_write_space;
579 
580 		newicsk->icsk_retransmits = 0;
581 		newicsk->icsk_backoff	  = 0;
582 		newicsk->icsk_probes_out  = 0;
583 
584 		/* Deinitialize accept_queue to trap illegal accesses. */
585 		memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
586 
587 		security_inet_csk_clone(newsk, req);
588 	}
589 	return newsk;
590 }
591 EXPORT_SYMBOL_GPL(inet_csk_clone);
592 
593 /*
594  * At this point, there should be no process reference to this
595  * socket, and thus no user references at all.  Therefore we
596  * can assume the socket waitqueue is inactive and nobody will
597  * try to jump onto it.
598  */
599 void inet_csk_destroy_sock(struct sock *sk)
600 {
601 	WARN_ON(sk->sk_state != TCP_CLOSE);
602 	WARN_ON(!sock_flag(sk, SOCK_DEAD));
603 
604 	/* It cannot be in hash table! */
605 	WARN_ON(!sk_unhashed(sk));
606 
607 	/* If it has not 0 inet_sk(sk)->inet_num, it must be bound */
608 	WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash);
609 
610 	sk->sk_prot->destroy(sk);
611 
612 	sk_stream_kill_queues(sk);
613 
614 	xfrm_sk_free_policy(sk);
615 
616 	sk_refcnt_debug_release(sk);
617 
618 	percpu_counter_dec(sk->sk_prot->orphan_count);
619 	sock_put(sk);
620 }
621 EXPORT_SYMBOL(inet_csk_destroy_sock);
622 
623 int inet_csk_listen_start(struct sock *sk, const int nr_table_entries)
624 {
625 	struct inet_sock *inet = inet_sk(sk);
626 	struct inet_connection_sock *icsk = inet_csk(sk);
627 	int rc = reqsk_queue_alloc(&icsk->icsk_accept_queue, nr_table_entries);
628 
629 	if (rc != 0)
630 		return rc;
631 
632 	sk->sk_max_ack_backlog = 0;
633 	sk->sk_ack_backlog = 0;
634 	inet_csk_delack_init(sk);
635 
636 	/* There is race window here: we announce ourselves listening,
637 	 * but this transition is still not validated by get_port().
638 	 * It is OK, because this socket enters to hash table only
639 	 * after validation is complete.
640 	 */
641 	sk->sk_state = TCP_LISTEN;
642 	if (!sk->sk_prot->get_port(sk, inet->inet_num)) {
643 		inet->inet_sport = htons(inet->inet_num);
644 
645 		sk_dst_reset(sk);
646 		sk->sk_prot->hash(sk);
647 
648 		return 0;
649 	}
650 
651 	sk->sk_state = TCP_CLOSE;
652 	__reqsk_queue_destroy(&icsk->icsk_accept_queue);
653 	return -EADDRINUSE;
654 }
655 EXPORT_SYMBOL_GPL(inet_csk_listen_start);
656 
657 /*
658  *	This routine closes sockets which have been at least partially
659  *	opened, but not yet accepted.
660  */
661 void inet_csk_listen_stop(struct sock *sk)
662 {
663 	struct inet_connection_sock *icsk = inet_csk(sk);
664 	struct request_sock *acc_req;
665 	struct request_sock *req;
666 
667 	inet_csk_delete_keepalive_timer(sk);
668 
669 	/* make all the listen_opt local to us */
670 	acc_req = reqsk_queue_yank_acceptq(&icsk->icsk_accept_queue);
671 
672 	/* Following specs, it would be better either to send FIN
673 	 * (and enter FIN-WAIT-1, it is normal close)
674 	 * or to send active reset (abort).
675 	 * Certainly, it is pretty dangerous while synflood, but it is
676 	 * bad justification for our negligence 8)
677 	 * To be honest, we are not able to make either
678 	 * of the variants now.			--ANK
679 	 */
680 	reqsk_queue_destroy(&icsk->icsk_accept_queue);
681 
682 	while ((req = acc_req) != NULL) {
683 		struct sock *child = req->sk;
684 
685 		acc_req = req->dl_next;
686 
687 		local_bh_disable();
688 		bh_lock_sock(child);
689 		WARN_ON(sock_owned_by_user(child));
690 		sock_hold(child);
691 
692 		sk->sk_prot->disconnect(child, O_NONBLOCK);
693 
694 		sock_orphan(child);
695 
696 		percpu_counter_inc(sk->sk_prot->orphan_count);
697 
698 		inet_csk_destroy_sock(child);
699 
700 		bh_unlock_sock(child);
701 		local_bh_enable();
702 		sock_put(child);
703 
704 		sk_acceptq_removed(sk);
705 		__reqsk_free(req);
706 	}
707 	WARN_ON(sk->sk_ack_backlog);
708 }
709 EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
710 
711 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
712 {
713 	struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
714 	const struct inet_sock *inet = inet_sk(sk);
715 
716 	sin->sin_family		= AF_INET;
717 	sin->sin_addr.s_addr	= inet->inet_daddr;
718 	sin->sin_port		= inet->inet_dport;
719 }
720 EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);
721 
722 #ifdef CONFIG_COMPAT
723 int inet_csk_compat_getsockopt(struct sock *sk, int level, int optname,
724 			       char __user *optval, int __user *optlen)
725 {
726 	const struct inet_connection_sock *icsk = inet_csk(sk);
727 
728 	if (icsk->icsk_af_ops->compat_getsockopt != NULL)
729 		return icsk->icsk_af_ops->compat_getsockopt(sk, level, optname,
730 							    optval, optlen);
731 	return icsk->icsk_af_ops->getsockopt(sk, level, optname,
732 					     optval, optlen);
733 }
734 EXPORT_SYMBOL_GPL(inet_csk_compat_getsockopt);
735 
736 int inet_csk_compat_setsockopt(struct sock *sk, int level, int optname,
737 			       char __user *optval, unsigned int optlen)
738 {
739 	const struct inet_connection_sock *icsk = inet_csk(sk);
740 
741 	if (icsk->icsk_af_ops->compat_setsockopt != NULL)
742 		return icsk->icsk_af_ops->compat_setsockopt(sk, level, optname,
743 							    optval, optlen);
744 	return icsk->icsk_af_ops->setsockopt(sk, level, optname,
745 					     optval, optlen);
746 }
747 EXPORT_SYMBOL_GPL(inet_csk_compat_setsockopt);
748 #endif
749