Linux/net/ipv4/inet_connection_sock.c

  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 

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