xref: /linux/net/ipv4/inet_connection_sock.c (revision 8ec3b8432e4fe8d452f88f1ed9a3450e715bb797)
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 flowi fl = { .oif = sk->sk_bound_dev_if,
360 			    .mark = sk->sk_mark,
361 			    .fl4_dst = ((opt && opt->srr) ?
362 					  opt->faddr : ireq->rmt_addr),
363 			    .fl4_src = ireq->loc_addr,
364 			    .fl4_tos = RT_CONN_FLAGS(sk),
365 			    .proto = sk->sk_protocol,
366 			    .flags = inet_sk_flowi_flags(sk),
367 			    .fl_ip_sport = inet_sk(sk)->inet_sport,
368 			    .fl_ip_dport = ireq->rmt_port };
369 	struct net *net = sock_net(sk);
370 
371 	security_req_classify_flow(req, &fl);
372 	if (ip_route_output_flow(net, &rt, &fl, sk, 0))
373 		goto no_route;
374 	if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway)
375 		goto route_err;
376 	return &rt->dst;
377 
378 route_err:
379 	ip_rt_put(rt);
380 no_route:
381 	IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES);
382 	return NULL;
383 }
384 EXPORT_SYMBOL_GPL(inet_csk_route_req);
385 
386 static inline u32 inet_synq_hash(const __be32 raddr, const __be16 rport,
387 				 const u32 rnd, const u32 synq_hsize)
388 {
389 	return jhash_2words((__force u32)raddr, (__force u32)rport, rnd) & (synq_hsize - 1);
390 }
391 
392 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
393 #define AF_INET_FAMILY(fam) ((fam) == AF_INET)
394 #else
395 #define AF_INET_FAMILY(fam) 1
396 #endif
397 
398 struct request_sock *inet_csk_search_req(const struct sock *sk,
399 					 struct request_sock ***prevp,
400 					 const __be16 rport, const __be32 raddr,
401 					 const __be32 laddr)
402 {
403 	const struct inet_connection_sock *icsk = inet_csk(sk);
404 	struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
405 	struct request_sock *req, **prev;
406 
407 	for (prev = &lopt->syn_table[inet_synq_hash(raddr, rport, lopt->hash_rnd,
408 						    lopt->nr_table_entries)];
409 	     (req = *prev) != NULL;
410 	     prev = &req->dl_next) {
411 		const struct inet_request_sock *ireq = inet_rsk(req);
412 
413 		if (ireq->rmt_port == rport &&
414 		    ireq->rmt_addr == raddr &&
415 		    ireq->loc_addr == laddr &&
416 		    AF_INET_FAMILY(req->rsk_ops->family)) {
417 			WARN_ON(req->sk);
418 			*prevp = prev;
419 			break;
420 		}
421 	}
422 
423 	return req;
424 }
425 EXPORT_SYMBOL_GPL(inet_csk_search_req);
426 
427 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
428 				   unsigned long timeout)
429 {
430 	struct inet_connection_sock *icsk = inet_csk(sk);
431 	struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
432 	const u32 h = inet_synq_hash(inet_rsk(req)->rmt_addr, inet_rsk(req)->rmt_port,
433 				     lopt->hash_rnd, lopt->nr_table_entries);
434 
435 	reqsk_queue_hash_req(&icsk->icsk_accept_queue, h, req, timeout);
436 	inet_csk_reqsk_queue_added(sk, timeout);
437 }
438 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
439 
440 /* Only thing we need from tcp.h */
441 extern int sysctl_tcp_synack_retries;
442 
443 
444 /* Decide when to expire the request and when to resend SYN-ACK */
445 static inline void syn_ack_recalc(struct request_sock *req, const int thresh,
446 				  const int max_retries,
447 				  const u8 rskq_defer_accept,
448 				  int *expire, int *resend)
449 {
450 	if (!rskq_defer_accept) {
451 		*expire = req->retrans >= thresh;
452 		*resend = 1;
453 		return;
454 	}
455 	*expire = req->retrans >= thresh &&
456 		  (!inet_rsk(req)->acked || req->retrans >= max_retries);
457 	/*
458 	 * Do not resend while waiting for data after ACK,
459 	 * start to resend on end of deferring period to give
460 	 * last chance for data or ACK to create established socket.
461 	 */
462 	*resend = !inet_rsk(req)->acked ||
463 		  req->retrans >= rskq_defer_accept - 1;
464 }
465 
466 void inet_csk_reqsk_queue_prune(struct sock *parent,
467 				const unsigned long interval,
468 				const unsigned long timeout,
469 				const unsigned long max_rto)
470 {
471 	struct inet_connection_sock *icsk = inet_csk(parent);
472 	struct request_sock_queue *queue = &icsk->icsk_accept_queue;
473 	struct listen_sock *lopt = queue->listen_opt;
474 	int max_retries = icsk->icsk_syn_retries ? : sysctl_tcp_synack_retries;
475 	int thresh = max_retries;
476 	unsigned long now = jiffies;
477 	struct request_sock **reqp, *req;
478 	int i, budget;
479 
480 	if (lopt == NULL || lopt->qlen == 0)
481 		return;
482 
483 	/* Normally all the openreqs are young and become mature
484 	 * (i.e. converted to established socket) for first timeout.
485 	 * If synack was not acknowledged for 3 seconds, it means
486 	 * one of the following things: synack was lost, ack was lost,
487 	 * rtt is high or nobody planned to ack (i.e. synflood).
488 	 * When server is a bit loaded, queue is populated with old
489 	 * open requests, reducing effective size of queue.
490 	 * When server is well loaded, queue size reduces to zero
491 	 * after several minutes of work. It is not synflood,
492 	 * it is normal operation. The solution is pruning
493 	 * too old entries overriding normal timeout, when
494 	 * situation becomes dangerous.
495 	 *
496 	 * Essentially, we reserve half of room for young
497 	 * embrions; and abort old ones without pity, if old
498 	 * ones are about to clog our table.
499 	 */
500 	if (lopt->qlen>>(lopt->max_qlen_log-1)) {
501 		int young = (lopt->qlen_young<<1);
502 
503 		while (thresh > 2) {
504 			if (lopt->qlen < young)
505 				break;
506 			thresh--;
507 			young <<= 1;
508 		}
509 	}
510 
511 	if (queue->rskq_defer_accept)
512 		max_retries = queue->rskq_defer_accept;
513 
514 	budget = 2 * (lopt->nr_table_entries / (timeout / interval));
515 	i = lopt->clock_hand;
516 
517 	do {
518 		reqp=&lopt->syn_table[i];
519 		while ((req = *reqp) != NULL) {
520 			if (time_after_eq(now, req->expires)) {
521 				int expire = 0, resend = 0;
522 
523 				syn_ack_recalc(req, thresh, max_retries,
524 					       queue->rskq_defer_accept,
525 					       &expire, &resend);
526 				if (req->rsk_ops->syn_ack_timeout)
527 					req->rsk_ops->syn_ack_timeout(parent, req);
528 				if (!expire &&
529 				    (!resend ||
530 				     !req->rsk_ops->rtx_syn_ack(parent, req, NULL) ||
531 				     inet_rsk(req)->acked)) {
532 					unsigned long timeo;
533 
534 					if (req->retrans++ == 0)
535 						lopt->qlen_young--;
536 					timeo = min((timeout << req->retrans), max_rto);
537 					req->expires = now + timeo;
538 					reqp = &req->dl_next;
539 					continue;
540 				}
541 
542 				/* Drop this request */
543 				inet_csk_reqsk_queue_unlink(parent, req, reqp);
544 				reqsk_queue_removed(queue, req);
545 				reqsk_free(req);
546 				continue;
547 			}
548 			reqp = &req->dl_next;
549 		}
550 
551 		i = (i + 1) & (lopt->nr_table_entries - 1);
552 
553 	} while (--budget > 0);
554 
555 	lopt->clock_hand = i;
556 
557 	if (lopt->qlen)
558 		inet_csk_reset_keepalive_timer(parent, interval);
559 }
560 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_prune);
561 
562 struct sock *inet_csk_clone(struct sock *sk, const struct request_sock *req,
563 			    const gfp_t priority)
564 {
565 	struct sock *newsk = sk_clone(sk, priority);
566 
567 	if (newsk != NULL) {
568 		struct inet_connection_sock *newicsk = inet_csk(newsk);
569 
570 		newsk->sk_state = TCP_SYN_RECV;
571 		newicsk->icsk_bind_hash = NULL;
572 
573 		inet_sk(newsk)->inet_dport = inet_rsk(req)->rmt_port;
574 		inet_sk(newsk)->inet_num = ntohs(inet_rsk(req)->loc_port);
575 		inet_sk(newsk)->inet_sport = inet_rsk(req)->loc_port;
576 		newsk->sk_write_space = sk_stream_write_space;
577 
578 		newicsk->icsk_retransmits = 0;
579 		newicsk->icsk_backoff	  = 0;
580 		newicsk->icsk_probes_out  = 0;
581 
582 		/* Deinitialize accept_queue to trap illegal accesses. */
583 		memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
584 
585 		security_inet_csk_clone(newsk, req);
586 	}
587 	return newsk;
588 }
589 EXPORT_SYMBOL_GPL(inet_csk_clone);
590 
591 /*
592  * At this point, there should be no process reference to this
593  * socket, and thus no user references at all.  Therefore we
594  * can assume the socket waitqueue is inactive and nobody will
595  * try to jump onto it.
596  */
597 void inet_csk_destroy_sock(struct sock *sk)
598 {
599 	WARN_ON(sk->sk_state != TCP_CLOSE);
600 	WARN_ON(!sock_flag(sk, SOCK_DEAD));
601 
602 	/* It cannot be in hash table! */
603 	WARN_ON(!sk_unhashed(sk));
604 
605 	/* If it has not 0 inet_sk(sk)->inet_num, it must be bound */
606 	WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash);
607 
608 	sk->sk_prot->destroy(sk);
609 
610 	sk_stream_kill_queues(sk);
611 
612 	xfrm_sk_free_policy(sk);
613 
614 	sk_refcnt_debug_release(sk);
615 
616 	percpu_counter_dec(sk->sk_prot->orphan_count);
617 	sock_put(sk);
618 }
619 EXPORT_SYMBOL(inet_csk_destroy_sock);
620 
621 int inet_csk_listen_start(struct sock *sk, const int nr_table_entries)
622 {
623 	struct inet_sock *inet = inet_sk(sk);
624 	struct inet_connection_sock *icsk = inet_csk(sk);
625 	int rc = reqsk_queue_alloc(&icsk->icsk_accept_queue, nr_table_entries);
626 
627 	if (rc != 0)
628 		return rc;
629 
630 	sk->sk_max_ack_backlog = 0;
631 	sk->sk_ack_backlog = 0;
632 	inet_csk_delack_init(sk);
633 
634 	/* There is race window here: we announce ourselves listening,
635 	 * but this transition is still not validated by get_port().
636 	 * It is OK, because this socket enters to hash table only
637 	 * after validation is complete.
638 	 */
639 	sk->sk_state = TCP_LISTEN;
640 	if (!sk->sk_prot->get_port(sk, inet->inet_num)) {
641 		inet->inet_sport = htons(inet->inet_num);
642 
643 		sk_dst_reset(sk);
644 		sk->sk_prot->hash(sk);
645 
646 		return 0;
647 	}
648 
649 	sk->sk_state = TCP_CLOSE;
650 	__reqsk_queue_destroy(&icsk->icsk_accept_queue);
651 	return -EADDRINUSE;
652 }
653 EXPORT_SYMBOL_GPL(inet_csk_listen_start);
654 
655 /*
656  *	This routine closes sockets which have been at least partially
657  *	opened, but not yet accepted.
658  */
659 void inet_csk_listen_stop(struct sock *sk)
660 {
661 	struct inet_connection_sock *icsk = inet_csk(sk);
662 	struct request_sock *acc_req;
663 	struct request_sock *req;
664 
665 	inet_csk_delete_keepalive_timer(sk);
666 
667 	/* make all the listen_opt local to us */
668 	acc_req = reqsk_queue_yank_acceptq(&icsk->icsk_accept_queue);
669 
670 	/* Following specs, it would be better either to send FIN
671 	 * (and enter FIN-WAIT-1, it is normal close)
672 	 * or to send active reset (abort).
673 	 * Certainly, it is pretty dangerous while synflood, but it is
674 	 * bad justification for our negligence 8)
675 	 * To be honest, we are not able to make either
676 	 * of the variants now.			--ANK
677 	 */
678 	reqsk_queue_destroy(&icsk->icsk_accept_queue);
679 
680 	while ((req = acc_req) != NULL) {
681 		struct sock *child = req->sk;
682 
683 		acc_req = req->dl_next;
684 
685 		local_bh_disable();
686 		bh_lock_sock(child);
687 		WARN_ON(sock_owned_by_user(child));
688 		sock_hold(child);
689 
690 		sk->sk_prot->disconnect(child, O_NONBLOCK);
691 
692 		sock_orphan(child);
693 
694 		percpu_counter_inc(sk->sk_prot->orphan_count);
695 
696 		inet_csk_destroy_sock(child);
697 
698 		bh_unlock_sock(child);
699 		local_bh_enable();
700 		sock_put(child);
701 
702 		sk_acceptq_removed(sk);
703 		__reqsk_free(req);
704 	}
705 	WARN_ON(sk->sk_ack_backlog);
706 }
707 EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
708 
709 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
710 {
711 	struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
712 	const struct inet_sock *inet = inet_sk(sk);
713 
714 	sin->sin_family		= AF_INET;
715 	sin->sin_addr.s_addr	= inet->inet_daddr;
716 	sin->sin_port		= inet->inet_dport;
717 }
718 EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);
719 
720 #ifdef CONFIG_COMPAT
721 int inet_csk_compat_getsockopt(struct sock *sk, int level, int optname,
722 			       char __user *optval, int __user *optlen)
723 {
724 	const struct inet_connection_sock *icsk = inet_csk(sk);
725 
726 	if (icsk->icsk_af_ops->compat_getsockopt != NULL)
727 		return icsk->icsk_af_ops->compat_getsockopt(sk, level, optname,
728 							    optval, optlen);
729 	return icsk->icsk_af_ops->getsockopt(sk, level, optname,
730 					     optval, optlen);
731 }
732 EXPORT_SYMBOL_GPL(inet_csk_compat_getsockopt);
733 
734 int inet_csk_compat_setsockopt(struct sock *sk, int level, int optname,
735 			       char __user *optval, unsigned int optlen)
736 {
737 	const struct inet_connection_sock *icsk = inet_csk(sk);
738 
739 	if (icsk->icsk_af_ops->compat_setsockopt != NULL)
740 		return icsk->icsk_af_ops->compat_setsockopt(sk, level, optname,
741 							    optval, optlen);
742 	return icsk->icsk_af_ops->setsockopt(sk, level, optname,
743 					     optval, optlen);
744 }
745 EXPORT_SYMBOL_GPL(inet_csk_compat_setsockopt);
746 #endif
747