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Arnaldo Carvalho de Melo3f421ba2005-08-09 20:11:08 -07001/*
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/config.h>
17#include <linux/module.h>
18#include <linux/jhash.h>
19
20#include <net/inet_connection_sock.h>
21#include <net/inet_hashtables.h>
22#include <net/inet_timewait_sock.h>
23#include <net/ip.h>
24#include <net/route.h>
25#include <net/tcp_states.h>
Arnaldo Carvalho de Meloa019d6f2005-08-09 20:15:09 -070026#include <net/xfrm.h>
Arnaldo Carvalho de Melo3f421ba2005-08-09 20:11:08 -070027
28#ifdef INET_CSK_DEBUG
29const char inet_csk_timer_bug_msg[] = "inet_csk BUG: unknown timer value\n";
30EXPORT_SYMBOL(inet_csk_timer_bug_msg);
31#endif
32
33/*
34 * This array holds the first and last local port number.
35 * For high-usage systems, use sysctl to change this to
36 * 32768-61000
37 */
38int sysctl_local_port_range[2] = { 1024, 4999 };
39
40static inline int inet_csk_bind_conflict(struct sock *sk, struct inet_bind_bucket *tb)
41{
42 const u32 sk_rcv_saddr = inet_rcv_saddr(sk);
43 struct sock *sk2;
44 struct hlist_node *node;
45 int reuse = sk->sk_reuse;
46
47 sk_for_each_bound(sk2, node, &tb->owners) {
48 if (sk != sk2 &&
49 !inet_v6_ipv6only(sk2) &&
50 (!sk->sk_bound_dev_if ||
51 !sk2->sk_bound_dev_if ||
52 sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
53 if (!reuse || !sk2->sk_reuse ||
54 sk2->sk_state == TCP_LISTEN) {
55 const u32 sk2_rcv_saddr = inet_rcv_saddr(sk2);
56 if (!sk2_rcv_saddr || !sk_rcv_saddr ||
57 sk2_rcv_saddr == sk_rcv_saddr)
58 break;
59 }
60 }
61 }
62 return node != NULL;
63}
64
65/* Obtain a reference to a local port for the given sock,
66 * if snum is zero it means select any available local port.
67 */
68int inet_csk_get_port(struct inet_hashinfo *hashinfo,
69 struct sock *sk, unsigned short snum)
70{
71 struct inet_bind_hashbucket *head;
72 struct hlist_node *node;
73 struct inet_bind_bucket *tb;
74 int ret;
75
76 local_bh_disable();
77 if (!snum) {
78 int low = sysctl_local_port_range[0];
79 int high = sysctl_local_port_range[1];
80 int remaining = (high - low) + 1;
81 int rover;
82
83 spin_lock(&hashinfo->portalloc_lock);
84 if (hashinfo->port_rover < low)
85 rover = low;
86 else
87 rover = hashinfo->port_rover;
88 do {
89 rover++;
90 if (rover > high)
91 rover = low;
92 head = &hashinfo->bhash[inet_bhashfn(rover, hashinfo->bhash_size)];
93 spin_lock(&head->lock);
94 inet_bind_bucket_for_each(tb, node, &head->chain)
95 if (tb->port == rover)
96 goto next;
97 break;
98 next:
99 spin_unlock(&head->lock);
100 } while (--remaining > 0);
101 hashinfo->port_rover = rover;
102 spin_unlock(&hashinfo->portalloc_lock);
103
104 /* Exhausted local port range during search? It is not
105 * possible for us to be holding one of the bind hash
106 * locks if this test triggers, because if 'remaining'
107 * drops to zero, we broke out of the do/while loop at
108 * the top level, not from the 'break;' statement.
109 */
110 ret = 1;
111 if (remaining <= 0)
112 goto fail;
113
114 /* OK, here is the one we will use. HEAD is
115 * non-NULL and we hold it's mutex.
116 */
117 snum = rover;
118 } else {
119 head = &hashinfo->bhash[inet_bhashfn(snum, hashinfo->bhash_size)];
120 spin_lock(&head->lock);
121 inet_bind_bucket_for_each(tb, node, &head->chain)
122 if (tb->port == snum)
123 goto tb_found;
124 }
125 tb = NULL;
126 goto tb_not_found;
127tb_found:
128 if (!hlist_empty(&tb->owners)) {
129 if (sk->sk_reuse > 1)
130 goto success;
131 if (tb->fastreuse > 0 &&
132 sk->sk_reuse && sk->sk_state != TCP_LISTEN) {
133 goto success;
134 } else {
135 ret = 1;
136 if (inet_csk_bind_conflict(sk, tb))
137 goto fail_unlock;
138 }
139 }
140tb_not_found:
141 ret = 1;
142 if (!tb && (tb = inet_bind_bucket_create(hashinfo->bind_bucket_cachep, head, snum)) == NULL)
143 goto fail_unlock;
144 if (hlist_empty(&tb->owners)) {
145 if (sk->sk_reuse && sk->sk_state != TCP_LISTEN)
146 tb->fastreuse = 1;
147 else
148 tb->fastreuse = 0;
149 } else if (tb->fastreuse &&
150 (!sk->sk_reuse || sk->sk_state == TCP_LISTEN))
151 tb->fastreuse = 0;
152success:
153 if (!inet_csk(sk)->icsk_bind_hash)
154 inet_bind_hash(sk, tb, snum);
155 BUG_TRAP(inet_csk(sk)->icsk_bind_hash == tb);
156 ret = 0;
157
158fail_unlock:
159 spin_unlock(&head->lock);
160fail:
161 local_bh_enable();
162 return ret;
163}
164
165EXPORT_SYMBOL_GPL(inet_csk_get_port);
166
167/*
168 * Wait for an incoming connection, avoid race conditions. This must be called
169 * with the socket locked.
170 */
171static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
172{
173 struct inet_connection_sock *icsk = inet_csk(sk);
174 DEFINE_WAIT(wait);
175 int err;
176
177 /*
178 * True wake-one mechanism for incoming connections: only
179 * one process gets woken up, not the 'whole herd'.
180 * Since we do not 'race & poll' for established sockets
181 * anymore, the common case will execute the loop only once.
182 *
183 * Subtle issue: "add_wait_queue_exclusive()" will be added
184 * after any current non-exclusive waiters, and we know that
185 * it will always _stay_ after any new non-exclusive waiters
186 * because all non-exclusive waiters are added at the
187 * beginning of the wait-queue. As such, it's ok to "drop"
188 * our exclusiveness temporarily when we get woken up without
189 * having to remove and re-insert us on the wait queue.
190 */
191 for (;;) {
192 prepare_to_wait_exclusive(sk->sk_sleep, &wait,
193 TASK_INTERRUPTIBLE);
194 release_sock(sk);
195 if (reqsk_queue_empty(&icsk->icsk_accept_queue))
196 timeo = schedule_timeout(timeo);
197 lock_sock(sk);
198 err = 0;
199 if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
200 break;
201 err = -EINVAL;
202 if (sk->sk_state != TCP_LISTEN)
203 break;
204 err = sock_intr_errno(timeo);
205 if (signal_pending(current))
206 break;
207 err = -EAGAIN;
208 if (!timeo)
209 break;
210 }
211 finish_wait(sk->sk_sleep, &wait);
212 return err;
213}
214
215/*
216 * This will accept the next outstanding connection.
217 */
218struct sock *inet_csk_accept(struct sock *sk, int flags, int *err)
219{
220 struct inet_connection_sock *icsk = inet_csk(sk);
221 struct sock *newsk;
222 int error;
223
224 lock_sock(sk);
225
226 /* We need to make sure that this socket is listening,
227 * and that it has something pending.
228 */
229 error = -EINVAL;
230 if (sk->sk_state != TCP_LISTEN)
231 goto out_err;
232
233 /* Find already established connection */
234 if (reqsk_queue_empty(&icsk->icsk_accept_queue)) {
235 long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
236
237 /* If this is a non blocking socket don't sleep */
238 error = -EAGAIN;
239 if (!timeo)
240 goto out_err;
241
242 error = inet_csk_wait_for_connect(sk, timeo);
243 if (error)
244 goto out_err;
245 }
246
247 newsk = reqsk_queue_get_child(&icsk->icsk_accept_queue, sk);
248 BUG_TRAP(newsk->sk_state != TCP_SYN_RECV);
249out:
250 release_sock(sk);
251 return newsk;
252out_err:
253 newsk = NULL;
254 *err = error;
255 goto out;
256}
257
258EXPORT_SYMBOL(inet_csk_accept);
259
260/*
261 * Using different timers for retransmit, delayed acks and probes
262 * We may wish use just one timer maintaining a list of expire jiffies
263 * to optimize.
264 */
265void inet_csk_init_xmit_timers(struct sock *sk,
266 void (*retransmit_handler)(unsigned long),
267 void (*delack_handler)(unsigned long),
268 void (*keepalive_handler)(unsigned long))
269{
270 struct inet_connection_sock *icsk = inet_csk(sk);
271
272 init_timer(&icsk->icsk_retransmit_timer);
273 init_timer(&icsk->icsk_delack_timer);
274 init_timer(&sk->sk_timer);
275
276 icsk->icsk_retransmit_timer.function = retransmit_handler;
277 icsk->icsk_delack_timer.function = delack_handler;
278 sk->sk_timer.function = keepalive_handler;
279
280 icsk->icsk_retransmit_timer.data =
281 icsk->icsk_delack_timer.data =
282 sk->sk_timer.data = (unsigned long)sk;
283
284 icsk->icsk_pending = icsk->icsk_ack.pending = 0;
285}
286
287EXPORT_SYMBOL(inet_csk_init_xmit_timers);
288
289void inet_csk_clear_xmit_timers(struct sock *sk)
290{
291 struct inet_connection_sock *icsk = inet_csk(sk);
292
293 icsk->icsk_pending = icsk->icsk_ack.pending = icsk->icsk_ack.blocked = 0;
294
295 sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
296 sk_stop_timer(sk, &icsk->icsk_delack_timer);
297 sk_stop_timer(sk, &sk->sk_timer);
298}
299
300EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
301
302void inet_csk_delete_keepalive_timer(struct sock *sk)
303{
304 sk_stop_timer(sk, &sk->sk_timer);
305}
306
307EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
308
309void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
310{
311 sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
312}
313
314EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
315
316struct dst_entry* inet_csk_route_req(struct sock *sk,
317 const struct request_sock *req)
318{
319 struct rtable *rt;
320 const struct inet_request_sock *ireq = inet_rsk(req);
321 struct ip_options *opt = inet_rsk(req)->opt;
322 struct flowi fl = { .oif = sk->sk_bound_dev_if,
323 .nl_u = { .ip4_u =
324 { .daddr = ((opt && opt->srr) ?
325 opt->faddr :
326 ireq->rmt_addr),
327 .saddr = ireq->loc_addr,
328 .tos = RT_CONN_FLAGS(sk) } },
329 .proto = sk->sk_protocol,
330 .uli_u = { .ports =
331 { .sport = inet_sk(sk)->sport,
332 .dport = ireq->rmt_port } } };
333
334 if (ip_route_output_flow(&rt, &fl, sk, 0)) {
335 IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES);
336 return NULL;
337 }
338 if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway) {
339 ip_rt_put(rt);
340 IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES);
341 return NULL;
342 }
343 return &rt->u.dst;
344}
345
346EXPORT_SYMBOL_GPL(inet_csk_route_req);
347
348static inline u32 inet_synq_hash(const u32 raddr, const u16 rport,
349 const u32 rnd, const u16 synq_hsize)
350{
351 return jhash_2words(raddr, (u32)rport, rnd) & (synq_hsize - 1);
352}
353
354#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
355#define AF_INET_FAMILY(fam) ((fam) == AF_INET)
356#else
357#define AF_INET_FAMILY(fam) 1
358#endif
359
360struct request_sock *inet_csk_search_req(const struct sock *sk,
361 struct request_sock ***prevp,
362 const __u16 rport, const __u32 raddr,
363 const __u32 laddr)
364{
365 const struct inet_connection_sock *icsk = inet_csk(sk);
366 struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
367 struct request_sock *req, **prev;
368
369 for (prev = &lopt->syn_table[inet_synq_hash(raddr, rport, lopt->hash_rnd,
370 lopt->nr_table_entries)];
371 (req = *prev) != NULL;
372 prev = &req->dl_next) {
373 const struct inet_request_sock *ireq = inet_rsk(req);
374
375 if (ireq->rmt_port == rport &&
376 ireq->rmt_addr == raddr &&
377 ireq->loc_addr == laddr &&
378 AF_INET_FAMILY(req->rsk_ops->family)) {
379 BUG_TRAP(!req->sk);
380 *prevp = prev;
381 break;
382 }
383 }
384
385 return req;
386}
387
388EXPORT_SYMBOL_GPL(inet_csk_search_req);
389
390void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
391 const unsigned timeout)
392{
393 struct inet_connection_sock *icsk = inet_csk(sk);
394 struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
395 const u32 h = inet_synq_hash(inet_rsk(req)->rmt_addr, inet_rsk(req)->rmt_port,
396 lopt->hash_rnd, lopt->nr_table_entries);
397
398 reqsk_queue_hash_req(&icsk->icsk_accept_queue, h, req, timeout);
399 inet_csk_reqsk_queue_added(sk, timeout);
400}
401
Arnaldo Carvalho de Meloa019d6f2005-08-09 20:15:09 -0700402/* Only thing we need from tcp.h */
403extern int sysctl_tcp_synack_retries;
404
Arnaldo Carvalho de Melo3f421ba2005-08-09 20:11:08 -0700405EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
Arnaldo Carvalho de Melo9f1d2602005-08-09 20:11:24 -0700406
Arnaldo Carvalho de Meloa019d6f2005-08-09 20:15:09 -0700407void inet_csk_reqsk_queue_prune(struct sock *parent,
408 const unsigned long interval,
409 const unsigned long timeout,
410 const unsigned long max_rto)
411{
412 struct inet_connection_sock *icsk = inet_csk(parent);
413 struct request_sock_queue *queue = &icsk->icsk_accept_queue;
414 struct listen_sock *lopt = queue->listen_opt;
415 int max_retries = icsk->icsk_syn_retries ? : sysctl_tcp_synack_retries;
416 int thresh = max_retries;
417 unsigned long now = jiffies;
418 struct request_sock **reqp, *req;
419 int i, budget;
420
421 if (lopt == NULL || lopt->qlen == 0)
422 return;
423
424 /* Normally all the openreqs are young and become mature
425 * (i.e. converted to established socket) for first timeout.
426 * If synack was not acknowledged for 3 seconds, it means
427 * one of the following things: synack was lost, ack was lost,
428 * rtt is high or nobody planned to ack (i.e. synflood).
429 * When server is a bit loaded, queue is populated with old
430 * open requests, reducing effective size of queue.
431 * When server is well loaded, queue size reduces to zero
432 * after several minutes of work. It is not synflood,
433 * it is normal operation. The solution is pruning
434 * too old entries overriding normal timeout, when
435 * situation becomes dangerous.
436 *
437 * Essentially, we reserve half of room for young
438 * embrions; and abort old ones without pity, if old
439 * ones are about to clog our table.
440 */
441 if (lopt->qlen>>(lopt->max_qlen_log-1)) {
442 int young = (lopt->qlen_young<<1);
443
444 while (thresh > 2) {
445 if (lopt->qlen < young)
446 break;
447 thresh--;
448 young <<= 1;
449 }
450 }
451
452 if (queue->rskq_defer_accept)
453 max_retries = queue->rskq_defer_accept;
454
455 budget = 2 * (lopt->nr_table_entries / (timeout / interval));
456 i = lopt->clock_hand;
457
458 do {
459 reqp=&lopt->syn_table[i];
460 while ((req = *reqp) != NULL) {
461 if (time_after_eq(now, req->expires)) {
462 if ((req->retrans < thresh ||
463 (inet_rsk(req)->acked && req->retrans < max_retries))
464 && !req->rsk_ops->rtx_syn_ack(parent, req, NULL)) {
465 unsigned long timeo;
466
467 if (req->retrans++ == 0)
468 lopt->qlen_young--;
469 timeo = min((timeout << req->retrans), max_rto);
470 req->expires = now + timeo;
471 reqp = &req->dl_next;
472 continue;
473 }
474
475 /* Drop this request */
476 inet_csk_reqsk_queue_unlink(parent, req, reqp);
477 reqsk_queue_removed(queue, req);
478 reqsk_free(req);
479 continue;
480 }
481 reqp = &req->dl_next;
482 }
483
484 i = (i + 1) & (lopt->nr_table_entries - 1);
485
486 } while (--budget > 0);
487
488 lopt->clock_hand = i;
489
490 if (lopt->qlen)
491 inet_csk_reset_keepalive_timer(parent, interval);
492}
493
494EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_prune);
495
Arnaldo Carvalho de Melo9f1d2602005-08-09 20:11:24 -0700496struct sock *inet_csk_clone(struct sock *sk, const struct request_sock *req,
497 const unsigned int __nocast priority)
498{
499 struct sock *newsk = sk_clone(sk, priority);
500
501 if (newsk != NULL) {
502 struct inet_connection_sock *newicsk = inet_csk(newsk);
503
504 newsk->sk_state = TCP_SYN_RECV;
505 newicsk->icsk_bind_hash = NULL;
506
507 inet_sk(newsk)->dport = inet_rsk(req)->rmt_port;
508 newsk->sk_write_space = sk_stream_write_space;
509
510 newicsk->icsk_retransmits = 0;
Arnaldo Carvalho de Melo6687e982005-08-10 04:03:31 -0300511 newicsk->icsk_backoff = 0;
512 newicsk->icsk_probes_out = 0;
Arnaldo Carvalho de Melo9f1d2602005-08-09 20:11:24 -0700513
514 /* Deinitialize accept_queue to trap illegal accesses. */
515 memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
516 }
517 return newsk;
518}
519
520EXPORT_SYMBOL_GPL(inet_csk_clone);
Arnaldo Carvalho de Meloa019d6f2005-08-09 20:15:09 -0700521
522/*
523 * At this point, there should be no process reference to this
524 * socket, and thus no user references at all. Therefore we
525 * can assume the socket waitqueue is inactive and nobody will
526 * try to jump onto it.
527 */
528void inet_csk_destroy_sock(struct sock *sk)
529{
530 BUG_TRAP(sk->sk_state == TCP_CLOSE);
531 BUG_TRAP(sock_flag(sk, SOCK_DEAD));
532
533 /* It cannot be in hash table! */
534 BUG_TRAP(sk_unhashed(sk));
535
536 /* If it has not 0 inet_sk(sk)->num, it must be bound */
537 BUG_TRAP(!inet_sk(sk)->num || inet_csk(sk)->icsk_bind_hash);
538
539 sk->sk_prot->destroy(sk);
540
541 sk_stream_kill_queues(sk);
542
543 xfrm_sk_free_policy(sk);
544
545 sk_refcnt_debug_release(sk);
546
547 atomic_dec(sk->sk_prot->orphan_count);
548 sock_put(sk);
549}
550
551EXPORT_SYMBOL(inet_csk_destroy_sock);
552
553int inet_csk_listen_start(struct sock *sk, const int nr_table_entries)
554{
555 struct inet_sock *inet = inet_sk(sk);
556 struct inet_connection_sock *icsk = inet_csk(sk);
557 int rc = reqsk_queue_alloc(&icsk->icsk_accept_queue, nr_table_entries);
558
559 if (rc != 0)
560 return rc;
561
562 sk->sk_max_ack_backlog = 0;
563 sk->sk_ack_backlog = 0;
564 inet_csk_delack_init(sk);
565
566 /* There is race window here: we announce ourselves listening,
567 * but this transition is still not validated by get_port().
568 * It is OK, because this socket enters to hash table only
569 * after validation is complete.
570 */
571 sk->sk_state = TCP_LISTEN;
572 if (!sk->sk_prot->get_port(sk, inet->num)) {
573 inet->sport = htons(inet->num);
574
575 sk_dst_reset(sk);
576 sk->sk_prot->hash(sk);
577
578 return 0;
579 }
580
581 sk->sk_state = TCP_CLOSE;
582 __reqsk_queue_destroy(&icsk->icsk_accept_queue);
583 return -EADDRINUSE;
584}
585
586EXPORT_SYMBOL_GPL(inet_csk_listen_start);
587
588/*
589 * This routine closes sockets which have been at least partially
590 * opened, but not yet accepted.
591 */
592void inet_csk_listen_stop(struct sock *sk)
593{
594 struct inet_connection_sock *icsk = inet_csk(sk);
595 struct request_sock *acc_req;
596 struct request_sock *req;
597
598 inet_csk_delete_keepalive_timer(sk);
599
600 /* make all the listen_opt local to us */
601 acc_req = reqsk_queue_yank_acceptq(&icsk->icsk_accept_queue);
602
603 /* Following specs, it would be better either to send FIN
604 * (and enter FIN-WAIT-1, it is normal close)
605 * or to send active reset (abort).
606 * Certainly, it is pretty dangerous while synflood, but it is
607 * bad justification for our negligence 8)
608 * To be honest, we are not able to make either
609 * of the variants now. --ANK
610 */
611 reqsk_queue_destroy(&icsk->icsk_accept_queue);
612
613 while ((req = acc_req) != NULL) {
614 struct sock *child = req->sk;
615
616 acc_req = req->dl_next;
617
618 local_bh_disable();
619 bh_lock_sock(child);
620 BUG_TRAP(!sock_owned_by_user(child));
621 sock_hold(child);
622
623 sk->sk_prot->disconnect(child, O_NONBLOCK);
624
625 sock_orphan(child);
626
627 atomic_inc(sk->sk_prot->orphan_count);
628
629 inet_csk_destroy_sock(child);
630
631 bh_unlock_sock(child);
632 local_bh_enable();
633 sock_put(child);
634
635 sk_acceptq_removed(sk);
636 __reqsk_free(req);
637 }
638 BUG_TRAP(!sk->sk_ack_backlog);
639}
640
641EXPORT_SYMBOL_GPL(inet_csk_listen_stop);