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 			    ((1 << sk2->sk_state) & (TCPF_LISTEN | TCPF_CLOSE))) {
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 						    !inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb)) {
127 							spin_unlock(&head->lock);
128 							snum = smallest_rover;
129 							goto have_snum;
130 						}
131 					}
132 					goto next;
133 				}
134 			break;
135 		next:
136 			spin_unlock(&head->lock);
137 		next_nolock:
138 			if (++rover > high)
139 				rover = low;
140 		} while (--remaining > 0);
141 
142 		/* Exhausted local port range during search?  It is not
143 		 * possible for us to be holding one of the bind hash
144 		 * locks if this test triggers, because if 'remaining'
145 		 * drops to zero, we broke out of the do/while loop at
146 		 * the top level, not from the 'break;' statement.
147 		 */
148 		ret = 1;
149 		if (remaining <= 0) {
150 			if (smallest_size != -1) {
151 				snum = smallest_rover;
152 				goto have_snum;
153 			}
154 			goto fail;
155 		}
156 		/* OK, here is the one we will use.  HEAD is
157 		 * non-NULL and we hold it's mutex.
158 		 */
159 		snum = rover;
160 	} else {
161 have_snum:
162 		head = &hashinfo->bhash[inet_bhashfn(net, snum,
163 				hashinfo->bhash_size)];
164 		spin_lock(&head->lock);
165 		inet_bind_bucket_for_each(tb, node, &head->chain)
166 			if (net_eq(ib_net(tb), net) && tb->port == snum)
167 				goto tb_found;
168 	}
169 	tb = NULL;
170 	goto tb_not_found;
171 tb_found:
172 	if (!hlist_empty(&tb->owners)) {
173 		if (tb->fastreuse > 0 &&
174 		    sk->sk_reuse && sk->sk_state != TCP_LISTEN &&
175 		    smallest_size == -1) {
176 			goto success;
177 		} else {
178 			ret = 1;
179 			if (inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb)) {
180 				if (sk->sk_reuse && sk->sk_state != TCP_LISTEN &&
181 				    smallest_size != -1 && --attempts >= 0) {
182 					spin_unlock(&head->lock);
183 					goto again;
184 				}
185 				goto fail_unlock;
186 			}
187 		}
188 	}
189 tb_not_found:
190 	ret = 1;
191 	if (!tb && (tb = inet_bind_bucket_create(hashinfo->bind_bucket_cachep,
192 					net, head, snum)) == NULL)
193 		goto fail_unlock;
194 	if (hlist_empty(&tb->owners)) {
195 		if (sk->sk_reuse && sk->sk_state != TCP_LISTEN)
196 			tb->fastreuse = 1;
197 		else
198 			tb->fastreuse = 0;
199 	} else if (tb->fastreuse &&
200 		   (!sk->sk_reuse || sk->sk_state == TCP_LISTEN))
201 		tb->fastreuse = 0;
202 success:
203 	if (!inet_csk(sk)->icsk_bind_hash)
204 		inet_bind_hash(sk, tb, snum);
205 	WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);
206 	ret = 0;
207 
208 fail_unlock:
209 	spin_unlock(&head->lock);
210 fail:
211 	local_bh_enable();
212 	return ret;
213 }
214 EXPORT_SYMBOL_GPL(inet_csk_get_port);
215 
216 /*
217  * Wait for an incoming connection, avoid race conditions. This must be called
218  * with the socket locked.
219  */
220 static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
221 {
222 	struct inet_connection_sock *icsk = inet_csk(sk);
223 	DEFINE_WAIT(wait);
224 	int err;
225 
226 	/*
227 	 * True wake-one mechanism for incoming connections: only
228 	 * one process gets woken up, not the 'whole herd'.
229 	 * Since we do not 'race & poll' for established sockets
230 	 * anymore, the common case will execute the loop only once.
231 	 *
232 	 * Subtle issue: "add_wait_queue_exclusive()" will be added
233 	 * after any current non-exclusive waiters, and we know that
234 	 * it will always _stay_ after any new non-exclusive waiters
235 	 * because all non-exclusive waiters are added at the
236 	 * beginning of the wait-queue. As such, it's ok to "drop"
237 	 * our exclusiveness temporarily when we get woken up without
238 	 * having to remove and re-insert us on the wait queue.
239 	 */
240 	for (;;) {
241 		prepare_to_wait_exclusive(sk_sleep(sk), &wait,
242 					  TASK_INTERRUPTIBLE);
243 		release_sock(sk);
244 		if (reqsk_queue_empty(&icsk->icsk_accept_queue))
245 			timeo = schedule_timeout(timeo);
246 		lock_sock(sk);
247 		err = 0;
248 		if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
249 			break;
250 		err = -EINVAL;
251 		if (sk->sk_state != TCP_LISTEN)
252 			break;
253 		err = sock_intr_errno(timeo);
254 		if (signal_pending(current))
255 			break;
256 		err = -EAGAIN;
257 		if (!timeo)
258 			break;
259 	}
260 	finish_wait(sk_sleep(sk), &wait);
261 	return err;
262 }
263 
264 /*
265  * This will accept the next outstanding connection.
266  */
267 struct sock *inet_csk_accept(struct sock *sk, int flags, int *err)
268 {
269 	struct inet_connection_sock *icsk = inet_csk(sk);
270 	struct sock *newsk;
271 	int error;
272 
273 	lock_sock(sk);
274 
275 	/* We need to make sure that this socket is listening,
276 	 * and that it has something pending.
277 	 */
278 	error = -EINVAL;
279 	if (sk->sk_state != TCP_LISTEN)
280 		goto out_err;
281 
282 	/* Find already established connection */
283 	if (reqsk_queue_empty(&icsk->icsk_accept_queue)) {
284 		long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
285 
286 		/* If this is a non blocking socket don't sleep */
287 		error = -EAGAIN;
288 		if (!timeo)
289 			goto out_err;
290 
291 		error = inet_csk_wait_for_connect(sk, timeo);
292 		if (error)
293 			goto out_err;
294 	}
295 
296 	newsk = reqsk_queue_get_child(&icsk->icsk_accept_queue, sk);
297 	WARN_ON(newsk->sk_state == TCP_SYN_RECV);
298 out:
299 	release_sock(sk);
300 	return newsk;
301 out_err:
302 	newsk = NULL;
303 	*err = error;
304 	goto out;
305 }
306 EXPORT_SYMBOL(inet_csk_accept);
307 
308 /*
309  * Using different timers for retransmit, delayed acks and probes
310  * We may wish use just one timer maintaining a list of expire jiffies
311  * to optimize.
312  */
313 void inet_csk_init_xmit_timers(struct sock *sk,
314 			       void (*retransmit_handler)(unsigned long),
315 			       void (*delack_handler)(unsigned long),
316 			       void (*keepalive_handler)(unsigned long))
317 {
318 	struct inet_connection_sock *icsk = inet_csk(sk);
319 
320 	setup_timer(&icsk->icsk_retransmit_timer, retransmit_handler,
321 			(unsigned long)sk);
322 	setup_timer(&icsk->icsk_delack_timer, delack_handler,
323 			(unsigned long)sk);
324 	setup_timer(&sk->sk_timer, keepalive_handler, (unsigned long)sk);
325 	icsk->icsk_pending = icsk->icsk_ack.pending = 0;
326 }
327 EXPORT_SYMBOL(inet_csk_init_xmit_timers);
328 
329 void inet_csk_clear_xmit_timers(struct sock *sk)
330 {
331 	struct inet_connection_sock *icsk = inet_csk(sk);
332 
333 	icsk->icsk_pending = icsk->icsk_ack.pending = icsk->icsk_ack.blocked = 0;
334 
335 	sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
336 	sk_stop_timer(sk, &icsk->icsk_delack_timer);
337 	sk_stop_timer(sk, &sk->sk_timer);
338 }
339 EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
340 
341 void inet_csk_delete_keepalive_timer(struct sock *sk)
342 {
343 	sk_stop_timer(sk, &sk->sk_timer);
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 EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
352 
353 struct dst_entry *inet_csk_route_req(struct sock *sk,
354 				     const struct request_sock *req)
355 {
356 	struct rtable *rt;
357 	const struct inet_request_sock *ireq = inet_rsk(req);
358 	struct ip_options *opt = inet_rsk(req)->opt;
359 	struct flowi4 fl4 = {
360 		.flowi4_oif = sk->sk_bound_dev_if,
361 		.flowi4_mark = sk->sk_mark,
362 		.daddr = ((opt && opt->srr) ?
363 			  opt->faddr : ireq->rmt_addr),
364 		.saddr = ireq->loc_addr,
365 		.flowi4_tos = RT_CONN_FLAGS(sk),
366 		.flowi4_proto = sk->sk_protocol,
367 		.flowi4_flags = inet_sk_flowi_flags(sk),
368 		.fl4_sport = inet_sk(sk)->inet_sport,
369 		.fl4_dport = ireq->rmt_port,
370 	};
371 	struct net *net = sock_net(sk);
372 
373 	security_req_classify_flow(req, flowi4_to_flowi(&fl4));
374 	rt = ip_route_output_flow(net, &fl4, sk);
375 	if (IS_ERR(rt))
376 		goto no_route;
377 	if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway)
378 		goto route_err;
379 	return &rt->dst;
380 
381 route_err:
382 	ip_rt_put(rt);
383 no_route:
384 	IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES);
385 	return NULL;
386 }
387 EXPORT_SYMBOL_GPL(inet_csk_route_req);
388 
389 static inline u32 inet_synq_hash(const __be32 raddr, const __be16 rport,
390 				 const u32 rnd, const u32 synq_hsize)
391 {
392 	return jhash_2words((__force u32)raddr, (__force u32)rport, rnd) & (synq_hsize - 1);
393 }
394 
395 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
396 #define AF_INET_FAMILY(fam) ((fam) == AF_INET)
397 #else
398 #define AF_INET_FAMILY(fam) 1
399 #endif
400 
401 struct request_sock *inet_csk_search_req(const struct sock *sk,
402 					 struct request_sock ***prevp,
403 					 const __be16 rport, const __be32 raddr,
404 					 const __be32 laddr)
405 {
406 	const struct inet_connection_sock *icsk = inet_csk(sk);
407 	struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
408 	struct request_sock *req, **prev;
409 
410 	for (prev = &lopt->syn_table[inet_synq_hash(raddr, rport, lopt->hash_rnd,
411 						    lopt->nr_table_entries)];
412 	     (req = *prev) != NULL;
413 	     prev = &req->dl_next) {
414 		const struct inet_request_sock *ireq = inet_rsk(req);
415 
416 		if (ireq->rmt_port == rport &&
417 		    ireq->rmt_addr == raddr &&
418 		    ireq->loc_addr == laddr &&
419 		    AF_INET_FAMILY(req->rsk_ops->family)) {
420 			WARN_ON(req->sk);
421 			*prevp = prev;
422 			break;
423 		}
424 	}
425 
426 	return req;
427 }
428 EXPORT_SYMBOL_GPL(inet_csk_search_req);
429 
430 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
431 				   unsigned long timeout)
432 {
433 	struct inet_connection_sock *icsk = inet_csk(sk);
434 	struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
435 	const u32 h = inet_synq_hash(inet_rsk(req)->rmt_addr, inet_rsk(req)->rmt_port,
436 				     lopt->hash_rnd, lopt->nr_table_entries);
437 
438 	reqsk_queue_hash_req(&icsk->icsk_accept_queue, h, req, timeout);
439 	inet_csk_reqsk_queue_added(sk, timeout);
440 }
441 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
442 
443 /* Only thing we need from tcp.h */
444 extern int sysctl_tcp_synack_retries;
445 
446 
447 /* Decide when to expire the request and when to resend SYN-ACK */
448 static inline void syn_ack_recalc(struct request_sock *req, const int thresh,
449 				  const int max_retries,
450 				  const u8 rskq_defer_accept,
451 				  int *expire, int *resend)
452 {
453 	if (!rskq_defer_accept) {
454 		*expire = req->retrans >= thresh;
455 		*resend = 1;
456 		return;
457 	}
458 	*expire = req->retrans >= thresh &&
459 		  (!inet_rsk(req)->acked || req->retrans >= max_retries);
460 	/*
461 	 * Do not resend while waiting for data after ACK,
462 	 * start to resend on end of deferring period to give
463 	 * last chance for data or ACK to create established socket.
464 	 */
465 	*resend = !inet_rsk(req)->acked ||
466 		  req->retrans >= rskq_defer_accept - 1;
467 }
468 
469 void inet_csk_reqsk_queue_prune(struct sock *parent,
470 				const unsigned long interval,
471 				const unsigned long timeout,
472 				const unsigned long max_rto)
473 {
474 	struct inet_connection_sock *icsk = inet_csk(parent);
475 	struct request_sock_queue *queue = &icsk->icsk_accept_queue;
476 	struct listen_sock *lopt = queue->listen_opt;
477 	int max_retries = icsk->icsk_syn_retries ? : sysctl_tcp_synack_retries;
478 	int thresh = max_retries;
479 	unsigned long now = jiffies;
480 	struct request_sock **reqp, *req;
481 	int i, budget;
482 
483 	if (lopt == NULL || lopt->qlen == 0)
484 		return;
485 
486 	/* Normally all the openreqs are young and become mature
487 	 * (i.e. converted to established socket) for first timeout.
488 	 * If synack was not acknowledged for 3 seconds, it means
489 	 * one of the following things: synack was lost, ack was lost,
490 	 * rtt is high or nobody planned to ack (i.e. synflood).
491 	 * When server is a bit loaded, queue is populated with old
492 	 * open requests, reducing effective size of queue.
493 	 * When server is well loaded, queue size reduces to zero
494 	 * after several minutes of work. It is not synflood,
495 	 * it is normal operation. The solution is pruning
496 	 * too old entries overriding normal timeout, when
497 	 * situation becomes dangerous.
498 	 *
499 	 * Essentially, we reserve half of room for young
500 	 * embrions; and abort old ones without pity, if old
501 	 * ones are about to clog our table.
502 	 */
503 	if (lopt->qlen>>(lopt->max_qlen_log-1)) {
504 		int young = (lopt->qlen_young<<1);
505 
506 		while (thresh > 2) {
507 			if (lopt->qlen < young)
508 				break;
509 			thresh--;
510 			young <<= 1;
511 		}
512 	}
513 
514 	if (queue->rskq_defer_accept)
515 		max_retries = queue->rskq_defer_accept;
516 
517 	budget = 2 * (lopt->nr_table_entries / (timeout / interval));
518 	i = lopt->clock_hand;
519 
520 	do {
521 		reqp=&lopt->syn_table[i];
522 		while ((req = *reqp) != NULL) {
523 			if (time_after_eq(now, req->expires)) {
524 				int expire = 0, resend = 0;
525 
526 				syn_ack_recalc(req, thresh, max_retries,
527 					       queue->rskq_defer_accept,
528 					       &expire, &resend);
529 				if (req->rsk_ops->syn_ack_timeout)
530 					req->rsk_ops->syn_ack_timeout(parent, req);
531 				if (!expire &&
532 				    (!resend ||
533 				     !req->rsk_ops->rtx_syn_ack(parent, req, NULL) ||
534 				     inet_rsk(req)->acked)) {
535 					unsigned long timeo;
536 
537 					if (req->retrans++ == 0)
538 						lopt->qlen_young--;
539 					timeo = min((timeout << req->retrans), max_rto);
540 					req->expires = now + timeo;
541 					reqp = &req->dl_next;
542 					continue;
543 				}
544 
545 				/* Drop this request */
546 				inet_csk_reqsk_queue_unlink(parent, req, reqp);
547 				reqsk_queue_removed(queue, req);
548 				reqsk_free(req);
549 				continue;
550 			}
551 			reqp = &req->dl_next;
552 		}
553 
554 		i = (i + 1) & (lopt->nr_table_entries - 1);
555 
556 	} while (--budget > 0);
557 
558 	lopt->clock_hand = i;
559 
560 	if (lopt->qlen)
561 		inet_csk_reset_keepalive_timer(parent, interval);
562 }
563 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_prune);
564 
565 struct sock *inet_csk_clone(struct sock *sk, const struct request_sock *req,
566 			    const gfp_t priority)
567 {
568 	struct sock *newsk = sk_clone(sk, priority);
569 
570 	if (newsk != NULL) {
571 		struct inet_connection_sock *newicsk = inet_csk(newsk);
572 
573 		newsk->sk_state = TCP_SYN_RECV;
574 		newicsk->icsk_bind_hash = NULL;
575 
576 		inet_sk(newsk)->inet_dport = inet_rsk(req)->rmt_port;
577 		inet_sk(newsk)->inet_num = ntohs(inet_rsk(req)->loc_port);
578 		inet_sk(newsk)->inet_sport = inet_rsk(req)->loc_port;
579 		newsk->sk_write_space = sk_stream_write_space;
580 
581 		newicsk->icsk_retransmits = 0;
582 		newicsk->icsk_backoff	  = 0;
583 		newicsk->icsk_probes_out  = 0;
584 
585 		/* Deinitialize accept_queue to trap illegal accesses. */
586 		memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
587 
588 		security_inet_csk_clone(newsk, req);
589 	}
590 	return newsk;
591 }
592 EXPORT_SYMBOL_GPL(inet_csk_clone);
593 
594 /*
595  * At this point, there should be no process reference to this
596  * socket, and thus no user references at all.  Therefore we
597  * can assume the socket waitqueue is inactive and nobody will
598  * try to jump onto it.
599  */
600 void inet_csk_destroy_sock(struct sock *sk)
601 {
602 	WARN_ON(sk->sk_state != TCP_CLOSE);
603 	WARN_ON(!sock_flag(sk, SOCK_DEAD));
604 
605 	/* It cannot be in hash table! */
606 	WARN_ON(!sk_unhashed(sk));
607 
608 	/* If it has not 0 inet_sk(sk)->inet_num, it must be bound */
609 	WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash);
610 
611 	sk->sk_prot->destroy(sk);
612 
613 	sk_stream_kill_queues(sk);
614 
615 	xfrm_sk_free_policy(sk);
616 
617 	sk_refcnt_debug_release(sk);
618 
619 	percpu_counter_dec(sk->sk_prot->orphan_count);
620 	sock_put(sk);
621 }
622 EXPORT_SYMBOL(inet_csk_destroy_sock);
623 
624 int inet_csk_listen_start(struct sock *sk, const int nr_table_entries)
625 {
626 	struct inet_sock *inet = inet_sk(sk);
627 	struct inet_connection_sock *icsk = inet_csk(sk);
628 	int rc = reqsk_queue_alloc(&icsk->icsk_accept_queue, nr_table_entries);
629 
630 	if (rc != 0)
631 		return rc;
632 
633 	sk->sk_max_ack_backlog = 0;
634 	sk->sk_ack_backlog = 0;
635 	inet_csk_delack_init(sk);
636 
637 	/* There is race window here: we announce ourselves listening,
638 	 * but this transition is still not validated by get_port().
639 	 * It is OK, because this socket enters to hash table only
640 	 * after validation is complete.
641 	 */
642 	sk->sk_state = TCP_LISTEN;
643 	if (!sk->sk_prot->get_port(sk, inet->inet_num)) {
644 		inet->inet_sport = htons(inet->inet_num);
645 
646 		sk_dst_reset(sk);
647 		sk->sk_prot->hash(sk);
648 
649 		return 0;
650 	}
651 
652 	sk->sk_state = TCP_CLOSE;
653 	__reqsk_queue_destroy(&icsk->icsk_accept_queue);
654 	return -EADDRINUSE;
655 }
656 EXPORT_SYMBOL_GPL(inet_csk_listen_start);
657 
658 /*
659  *	This routine closes sockets which have been at least partially
660  *	opened, but not yet accepted.
661  */
662 void inet_csk_listen_stop(struct sock *sk)
663 {
664 	struct inet_connection_sock *icsk = inet_csk(sk);
665 	struct request_sock *acc_req;
666 	struct request_sock *req;
667 
668 	inet_csk_delete_keepalive_timer(sk);
669 
670 	/* make all the listen_opt local to us */
671 	acc_req = reqsk_queue_yank_acceptq(&icsk->icsk_accept_queue);
672 
673 	/* Following specs, it would be better either to send FIN
674 	 * (and enter FIN-WAIT-1, it is normal close)
675 	 * or to send active reset (abort).
676 	 * Certainly, it is pretty dangerous while synflood, but it is
677 	 * bad justification for our negligence 8)
678 	 * To be honest, we are not able to make either
679 	 * of the variants now.			--ANK
680 	 */
681 	reqsk_queue_destroy(&icsk->icsk_accept_queue);
682 
683 	while ((req = acc_req) != NULL) {
684 		struct sock *child = req->sk;
685 
686 		acc_req = req->dl_next;
687 
688 		local_bh_disable();
689 		bh_lock_sock(child);
690 		WARN_ON(sock_owned_by_user(child));
691 		sock_hold(child);
692 
693 		sk->sk_prot->disconnect(child, O_NONBLOCK);
694 
695 		sock_orphan(child);
696 
697 		percpu_counter_inc(sk->sk_prot->orphan_count);
698 
699 		inet_csk_destroy_sock(child);
700 
701 		bh_unlock_sock(child);
702 		local_bh_enable();
703 		sock_put(child);
704 
705 		sk_acceptq_removed(sk);
706 		__reqsk_free(req);
707 	}
708 	WARN_ON(sk->sk_ack_backlog);
709 }
710 EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
711 
712 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
713 {
714 	struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
715 	const struct inet_sock *inet = inet_sk(sk);
716 
717 	sin->sin_family		= AF_INET;
718 	sin->sin_addr.s_addr	= inet->inet_daddr;
719 	sin->sin_port		= inet->inet_dport;
720 }
721 EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);
722 
723 #ifdef CONFIG_COMPAT
724 int inet_csk_compat_getsockopt(struct sock *sk, int level, int optname,
725 			       char __user *optval, int __user *optlen)
726 {
727 	const struct inet_connection_sock *icsk = inet_csk(sk);
728 
729 	if (icsk->icsk_af_ops->compat_getsockopt != NULL)
730 		return icsk->icsk_af_ops->compat_getsockopt(sk, level, optname,
731 							    optval, optlen);
732 	return icsk->icsk_af_ops->getsockopt(sk, level, optname,
733 					     optval, optlen);
734 }
735 EXPORT_SYMBOL_GPL(inet_csk_compat_getsockopt);
736 
737 int inet_csk_compat_setsockopt(struct sock *sk, int level, int optname,
738 			       char __user *optval, unsigned int optlen)
739 {
740 	const struct inet_connection_sock *icsk = inet_csk(sk);
741 
742 	if (icsk->icsk_af_ops->compat_setsockopt != NULL)
743 		return icsk->icsk_af_ops->compat_setsockopt(sk, level, optname,
744 							    optval, optlen);
745 	return icsk->icsk_af_ops->setsockopt(sk, level, optname,
746 					     optval, optlen);
747 }
748 EXPORT_SYMBOL_GPL(inet_csk_compat_setsockopt);
749 #endif
750