[ARM] Support register switch in nommu mode
[linux-2.6/verdex.git] / net / ipv4 / inet_connection_sock.c
blobae20281d8deb085e58eec67def12fef96da3b1fd
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.
6 * Support for INET connection oriented protocols.
8 * Authors: See the TCP sources
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.
16 #include <linux/config.h>
17 #include <linux/module.h>
18 #include <linux/jhash.h>
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>
26 #include <net/xfrm.h>
28 #ifdef INET_CSK_DEBUG
29 const char inet_csk_timer_bug_msg[] = "inet_csk BUG: unknown timer value\n";
30 EXPORT_SYMBOL(inet_csk_timer_bug_msg);
31 #endif
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
38 int sysctl_local_port_range[2] = { 1024, 4999 };
40 int inet_csk_bind_conflict(const struct sock *sk,
41 const struct inet_bind_bucket *tb)
43 const u32 sk_rcv_saddr = inet_rcv_saddr(sk);
44 struct sock *sk2;
45 struct hlist_node *node;
46 int reuse = sk->sk_reuse;
48 sk_for_each_bound(sk2, node, &tb->owners) {
49 if (sk != sk2 &&
50 !inet_v6_ipv6only(sk2) &&
51 (!sk->sk_bound_dev_if ||
52 !sk2->sk_bound_dev_if ||
53 sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
54 if (!reuse || !sk2->sk_reuse ||
55 sk2->sk_state == TCP_LISTEN) {
56 const u32 sk2_rcv_saddr = inet_rcv_saddr(sk2);
57 if (!sk2_rcv_saddr || !sk_rcv_saddr ||
58 sk2_rcv_saddr == sk_rcv_saddr)
59 break;
63 return node != NULL;
66 EXPORT_SYMBOL_GPL(inet_csk_bind_conflict);
68 /* Obtain a reference to a local port for the given sock,
69 * if snum is zero it means select any available local port.
71 int inet_csk_get_port(struct inet_hashinfo *hashinfo,
72 struct sock *sk, unsigned short snum,
73 int (*bind_conflict)(const struct sock *sk,
74 const struct inet_bind_bucket *tb))
76 struct inet_bind_hashbucket *head;
77 struct hlist_node *node;
78 struct inet_bind_bucket *tb;
79 int ret;
81 local_bh_disable();
82 if (!snum) {
83 int low = sysctl_local_port_range[0];
84 int high = sysctl_local_port_range[1];
85 int remaining = (high - low) + 1;
86 int rover = net_random() % (high - low) + low;
88 do {
89 head = &hashinfo->bhash[inet_bhashfn(rover, hashinfo->bhash_size)];
90 spin_lock(&head->lock);
91 inet_bind_bucket_for_each(tb, node, &head->chain)
92 if (tb->port == rover)
93 goto next;
94 break;
95 next:
96 spin_unlock(&head->lock);
97 if (++rover > high)
98 rover = low;
99 } while (--remaining > 0);
101 /* Exhausted local port range during search? It is not
102 * possible for us to be holding one of the bind hash
103 * locks if this test triggers, because if 'remaining'
104 * drops to zero, we broke out of the do/while loop at
105 * the top level, not from the 'break;' statement.
107 ret = 1;
108 if (remaining <= 0)
109 goto fail;
111 /* OK, here is the one we will use. HEAD is
112 * non-NULL and we hold it's mutex.
114 snum = rover;
115 } else {
116 head = &hashinfo->bhash[inet_bhashfn(snum, hashinfo->bhash_size)];
117 spin_lock(&head->lock);
118 inet_bind_bucket_for_each(tb, node, &head->chain)
119 if (tb->port == snum)
120 goto tb_found;
122 tb = NULL;
123 goto tb_not_found;
124 tb_found:
125 if (!hlist_empty(&tb->owners)) {
126 if (sk->sk_reuse > 1)
127 goto success;
128 if (tb->fastreuse > 0 &&
129 sk->sk_reuse && sk->sk_state != TCP_LISTEN) {
130 goto success;
131 } else {
132 ret = 1;
133 if (bind_conflict(sk, tb))
134 goto fail_unlock;
137 tb_not_found:
138 ret = 1;
139 if (!tb && (tb = inet_bind_bucket_create(hashinfo->bind_bucket_cachep, head, snum)) == NULL)
140 goto fail_unlock;
141 if (hlist_empty(&tb->owners)) {
142 if (sk->sk_reuse && sk->sk_state != TCP_LISTEN)
143 tb->fastreuse = 1;
144 else
145 tb->fastreuse = 0;
146 } else if (tb->fastreuse &&
147 (!sk->sk_reuse || sk->sk_state == TCP_LISTEN))
148 tb->fastreuse = 0;
149 success:
150 if (!inet_csk(sk)->icsk_bind_hash)
151 inet_bind_hash(sk, tb, snum);
152 BUG_TRAP(inet_csk(sk)->icsk_bind_hash == tb);
153 ret = 0;
155 fail_unlock:
156 spin_unlock(&head->lock);
157 fail:
158 local_bh_enable();
159 return ret;
162 EXPORT_SYMBOL_GPL(inet_csk_get_port);
165 * Wait for an incoming connection, avoid race conditions. This must be called
166 * with the socket locked.
168 static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
170 struct inet_connection_sock *icsk = inet_csk(sk);
171 DEFINE_WAIT(wait);
172 int err;
175 * True wake-one mechanism for incoming connections: only
176 * one process gets woken up, not the 'whole herd'.
177 * Since we do not 'race & poll' for established sockets
178 * anymore, the common case will execute the loop only once.
180 * Subtle issue: "add_wait_queue_exclusive()" will be added
181 * after any current non-exclusive waiters, and we know that
182 * it will always _stay_ after any new non-exclusive waiters
183 * because all non-exclusive waiters are added at the
184 * beginning of the wait-queue. As such, it's ok to "drop"
185 * our exclusiveness temporarily when we get woken up without
186 * having to remove and re-insert us on the wait queue.
188 for (;;) {
189 prepare_to_wait_exclusive(sk->sk_sleep, &wait,
190 TASK_INTERRUPTIBLE);
191 release_sock(sk);
192 if (reqsk_queue_empty(&icsk->icsk_accept_queue))
193 timeo = schedule_timeout(timeo);
194 lock_sock(sk);
195 err = 0;
196 if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
197 break;
198 err = -EINVAL;
199 if (sk->sk_state != TCP_LISTEN)
200 break;
201 err = sock_intr_errno(timeo);
202 if (signal_pending(current))
203 break;
204 err = -EAGAIN;
205 if (!timeo)
206 break;
208 finish_wait(sk->sk_sleep, &wait);
209 return err;
213 * This will accept the next outstanding connection.
215 struct sock *inet_csk_accept(struct sock *sk, int flags, int *err)
217 struct inet_connection_sock *icsk = inet_csk(sk);
218 struct sock *newsk;
219 int error;
221 lock_sock(sk);
223 /* We need to make sure that this socket is listening,
224 * and that it has something pending.
226 error = -EINVAL;
227 if (sk->sk_state != TCP_LISTEN)
228 goto out_err;
230 /* Find already established connection */
231 if (reqsk_queue_empty(&icsk->icsk_accept_queue)) {
232 long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
234 /* If this is a non blocking socket don't sleep */
235 error = -EAGAIN;
236 if (!timeo)
237 goto out_err;
239 error = inet_csk_wait_for_connect(sk, timeo);
240 if (error)
241 goto out_err;
244 newsk = reqsk_queue_get_child(&icsk->icsk_accept_queue, sk);
245 BUG_TRAP(newsk->sk_state != TCP_SYN_RECV);
246 out:
247 release_sock(sk);
248 return newsk;
249 out_err:
250 newsk = NULL;
251 *err = error;
252 goto out;
255 EXPORT_SYMBOL(inet_csk_accept);
258 * Using different timers for retransmit, delayed acks and probes
259 * We may wish use just one timer maintaining a list of expire jiffies
260 * to optimize.
262 void inet_csk_init_xmit_timers(struct sock *sk,
263 void (*retransmit_handler)(unsigned long),
264 void (*delack_handler)(unsigned long),
265 void (*keepalive_handler)(unsigned long))
267 struct inet_connection_sock *icsk = inet_csk(sk);
269 init_timer(&icsk->icsk_retransmit_timer);
270 init_timer(&icsk->icsk_delack_timer);
271 init_timer(&sk->sk_timer);
273 icsk->icsk_retransmit_timer.function = retransmit_handler;
274 icsk->icsk_delack_timer.function = delack_handler;
275 sk->sk_timer.function = keepalive_handler;
277 icsk->icsk_retransmit_timer.data =
278 icsk->icsk_delack_timer.data =
279 sk->sk_timer.data = (unsigned long)sk;
281 icsk->icsk_pending = icsk->icsk_ack.pending = 0;
284 EXPORT_SYMBOL(inet_csk_init_xmit_timers);
286 void inet_csk_clear_xmit_timers(struct sock *sk)
288 struct inet_connection_sock *icsk = inet_csk(sk);
290 icsk->icsk_pending = icsk->icsk_ack.pending = icsk->icsk_ack.blocked = 0;
292 sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
293 sk_stop_timer(sk, &icsk->icsk_delack_timer);
294 sk_stop_timer(sk, &sk->sk_timer);
297 EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
299 void inet_csk_delete_keepalive_timer(struct sock *sk)
301 sk_stop_timer(sk, &sk->sk_timer);
304 EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
306 void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
308 sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
311 EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
313 struct dst_entry* inet_csk_route_req(struct sock *sk,
314 const struct request_sock *req)
316 struct rtable *rt;
317 const struct inet_request_sock *ireq = inet_rsk(req);
318 struct ip_options *opt = inet_rsk(req)->opt;
319 struct flowi fl = { .oif = sk->sk_bound_dev_if,
320 .nl_u = { .ip4_u =
321 { .daddr = ((opt && opt->srr) ?
322 opt->faddr :
323 ireq->rmt_addr),
324 .saddr = ireq->loc_addr,
325 .tos = RT_CONN_FLAGS(sk) } },
326 .proto = sk->sk_protocol,
327 .uli_u = { .ports =
328 { .sport = inet_sk(sk)->sport,
329 .dport = ireq->rmt_port } } };
331 if (ip_route_output_flow(&rt, &fl, sk, 0)) {
332 IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES);
333 return NULL;
335 if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway) {
336 ip_rt_put(rt);
337 IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES);
338 return NULL;
340 return &rt->u.dst;
343 EXPORT_SYMBOL_GPL(inet_csk_route_req);
345 static inline u32 inet_synq_hash(const u32 raddr, const u16 rport,
346 const u32 rnd, const u16 synq_hsize)
348 return jhash_2words(raddr, (u32)rport, rnd) & (synq_hsize - 1);
351 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
352 #define AF_INET_FAMILY(fam) ((fam) == AF_INET)
353 #else
354 #define AF_INET_FAMILY(fam) 1
355 #endif
357 struct request_sock *inet_csk_search_req(const struct sock *sk,
358 struct request_sock ***prevp,
359 const __u16 rport, const __u32 raddr,
360 const __u32 laddr)
362 const struct inet_connection_sock *icsk = inet_csk(sk);
363 struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
364 struct request_sock *req, **prev;
366 for (prev = &lopt->syn_table[inet_synq_hash(raddr, rport, lopt->hash_rnd,
367 lopt->nr_table_entries)];
368 (req = *prev) != NULL;
369 prev = &req->dl_next) {
370 const struct inet_request_sock *ireq = inet_rsk(req);
372 if (ireq->rmt_port == rport &&
373 ireq->rmt_addr == raddr &&
374 ireq->loc_addr == laddr &&
375 AF_INET_FAMILY(req->rsk_ops->family)) {
376 BUG_TRAP(!req->sk);
377 *prevp = prev;
378 break;
382 return req;
385 EXPORT_SYMBOL_GPL(inet_csk_search_req);
387 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
388 unsigned long timeout)
390 struct inet_connection_sock *icsk = inet_csk(sk);
391 struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
392 const u32 h = inet_synq_hash(inet_rsk(req)->rmt_addr, inet_rsk(req)->rmt_port,
393 lopt->hash_rnd, lopt->nr_table_entries);
395 reqsk_queue_hash_req(&icsk->icsk_accept_queue, h, req, timeout);
396 inet_csk_reqsk_queue_added(sk, timeout);
399 /* Only thing we need from tcp.h */
400 extern int sysctl_tcp_synack_retries;
402 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
404 void inet_csk_reqsk_queue_prune(struct sock *parent,
405 const unsigned long interval,
406 const unsigned long timeout,
407 const unsigned long max_rto)
409 struct inet_connection_sock *icsk = inet_csk(parent);
410 struct request_sock_queue *queue = &icsk->icsk_accept_queue;
411 struct listen_sock *lopt = queue->listen_opt;
412 int max_retries = icsk->icsk_syn_retries ? : sysctl_tcp_synack_retries;
413 int thresh = max_retries;
414 unsigned long now = jiffies;
415 struct request_sock **reqp, *req;
416 int i, budget;
418 if (lopt == NULL || lopt->qlen == 0)
419 return;
421 /* Normally all the openreqs are young and become mature
422 * (i.e. converted to established socket) for first timeout.
423 * If synack was not acknowledged for 3 seconds, it means
424 * one of the following things: synack was lost, ack was lost,
425 * rtt is high or nobody planned to ack (i.e. synflood).
426 * When server is a bit loaded, queue is populated with old
427 * open requests, reducing effective size of queue.
428 * When server is well loaded, queue size reduces to zero
429 * after several minutes of work. It is not synflood,
430 * it is normal operation. The solution is pruning
431 * too old entries overriding normal timeout, when
432 * situation becomes dangerous.
434 * Essentially, we reserve half of room for young
435 * embrions; and abort old ones without pity, if old
436 * ones are about to clog our table.
438 if (lopt->qlen>>(lopt->max_qlen_log-1)) {
439 int young = (lopt->qlen_young<<1);
441 while (thresh > 2) {
442 if (lopt->qlen < young)
443 break;
444 thresh--;
445 young <<= 1;
449 if (queue->rskq_defer_accept)
450 max_retries = queue->rskq_defer_accept;
452 budget = 2 * (lopt->nr_table_entries / (timeout / interval));
453 i = lopt->clock_hand;
455 do {
456 reqp=&lopt->syn_table[i];
457 while ((req = *reqp) != NULL) {
458 if (time_after_eq(now, req->expires)) {
459 if ((req->retrans < thresh ||
460 (inet_rsk(req)->acked && req->retrans < max_retries))
461 && !req->rsk_ops->rtx_syn_ack(parent, req, NULL)) {
462 unsigned long timeo;
464 if (req->retrans++ == 0)
465 lopt->qlen_young--;
466 timeo = min((timeout << req->retrans), max_rto);
467 req->expires = now + timeo;
468 reqp = &req->dl_next;
469 continue;
472 /* Drop this request */
473 inet_csk_reqsk_queue_unlink(parent, req, reqp);
474 reqsk_queue_removed(queue, req);
475 reqsk_free(req);
476 continue;
478 reqp = &req->dl_next;
481 i = (i + 1) & (lopt->nr_table_entries - 1);
483 } while (--budget > 0);
485 lopt->clock_hand = i;
487 if (lopt->qlen)
488 inet_csk_reset_keepalive_timer(parent, interval);
491 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_prune);
493 struct sock *inet_csk_clone(struct sock *sk, const struct request_sock *req,
494 const gfp_t priority)
496 struct sock *newsk = sk_clone(sk, priority);
498 if (newsk != NULL) {
499 struct inet_connection_sock *newicsk = inet_csk(newsk);
501 newsk->sk_state = TCP_SYN_RECV;
502 newicsk->icsk_bind_hash = NULL;
504 inet_sk(newsk)->dport = inet_rsk(req)->rmt_port;
505 newsk->sk_write_space = sk_stream_write_space;
507 newicsk->icsk_retransmits = 0;
508 newicsk->icsk_backoff = 0;
509 newicsk->icsk_probes_out = 0;
511 /* Deinitialize accept_queue to trap illegal accesses. */
512 memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
514 return newsk;
517 EXPORT_SYMBOL_GPL(inet_csk_clone);
520 * At this point, there should be no process reference to this
521 * socket, and thus no user references at all. Therefore we
522 * can assume the socket waitqueue is inactive and nobody will
523 * try to jump onto it.
525 void inet_csk_destroy_sock(struct sock *sk)
527 BUG_TRAP(sk->sk_state == TCP_CLOSE);
528 BUG_TRAP(sock_flag(sk, SOCK_DEAD));
530 /* It cannot be in hash table! */
531 BUG_TRAP(sk_unhashed(sk));
533 /* If it has not 0 inet_sk(sk)->num, it must be bound */
534 BUG_TRAP(!inet_sk(sk)->num || inet_csk(sk)->icsk_bind_hash);
536 sk->sk_prot->destroy(sk);
538 sk_stream_kill_queues(sk);
540 xfrm_sk_free_policy(sk);
542 sk_refcnt_debug_release(sk);
544 atomic_dec(sk->sk_prot->orphan_count);
545 sock_put(sk);
548 EXPORT_SYMBOL(inet_csk_destroy_sock);
550 int inet_csk_listen_start(struct sock *sk, const int nr_table_entries)
552 struct inet_sock *inet = inet_sk(sk);
553 struct inet_connection_sock *icsk = inet_csk(sk);
554 int rc = reqsk_queue_alloc(&icsk->icsk_accept_queue, nr_table_entries);
556 if (rc != 0)
557 return rc;
559 sk->sk_max_ack_backlog = 0;
560 sk->sk_ack_backlog = 0;
561 inet_csk_delack_init(sk);
563 /* There is race window here: we announce ourselves listening,
564 * but this transition is still not validated by get_port().
565 * It is OK, because this socket enters to hash table only
566 * after validation is complete.
568 sk->sk_state = TCP_LISTEN;
569 if (!sk->sk_prot->get_port(sk, inet->num)) {
570 inet->sport = htons(inet->num);
572 sk_dst_reset(sk);
573 sk->sk_prot->hash(sk);
575 return 0;
578 sk->sk_state = TCP_CLOSE;
579 __reqsk_queue_destroy(&icsk->icsk_accept_queue);
580 return -EADDRINUSE;
583 EXPORT_SYMBOL_GPL(inet_csk_listen_start);
586 * This routine closes sockets which have been at least partially
587 * opened, but not yet accepted.
589 void inet_csk_listen_stop(struct sock *sk)
591 struct inet_connection_sock *icsk = inet_csk(sk);
592 struct request_sock *acc_req;
593 struct request_sock *req;
595 inet_csk_delete_keepalive_timer(sk);
597 /* make all the listen_opt local to us */
598 acc_req = reqsk_queue_yank_acceptq(&icsk->icsk_accept_queue);
600 /* Following specs, it would be better either to send FIN
601 * (and enter FIN-WAIT-1, it is normal close)
602 * or to send active reset (abort).
603 * Certainly, it is pretty dangerous while synflood, but it is
604 * bad justification for our negligence 8)
605 * To be honest, we are not able to make either
606 * of the variants now. --ANK
608 reqsk_queue_destroy(&icsk->icsk_accept_queue);
610 while ((req = acc_req) != NULL) {
611 struct sock *child = req->sk;
613 acc_req = req->dl_next;
615 local_bh_disable();
616 bh_lock_sock(child);
617 BUG_TRAP(!sock_owned_by_user(child));
618 sock_hold(child);
620 sk->sk_prot->disconnect(child, O_NONBLOCK);
622 sock_orphan(child);
624 atomic_inc(sk->sk_prot->orphan_count);
626 inet_csk_destroy_sock(child);
628 bh_unlock_sock(child);
629 local_bh_enable();
630 sock_put(child);
632 sk_acceptq_removed(sk);
633 __reqsk_free(req);
635 BUG_TRAP(!sk->sk_ack_backlog);
638 EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
640 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
642 struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
643 const struct inet_sock *inet = inet_sk(sk);
645 sin->sin_family = AF_INET;
646 sin->sin_addr.s_addr = inet->daddr;
647 sin->sin_port = inet->dport;
650 EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);