Version:  2.0.40 2.2.26 2.4.37 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18

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(sysctl_local_ports.lock),
 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 int seq;
 46 
 47         do {
 48                 seq = read_seqbegin(&sysctl_local_ports.lock);
 49 
 50                 *low = sysctl_local_ports.range[0];
 51                 *high = sysctl_local_ports.range[1];
 52         } while (read_seqretry(&sysctl_local_ports.lock, seq));
 53 }
 54 EXPORT_SYMBOL(inet_get_local_port_range);
 55 
 56 int inet_csk_bind_conflict(const struct sock *sk,
 57                            const struct inet_bind_bucket *tb, bool relax)
 58 {
 59         struct sock *sk2;
 60         int reuse = sk->sk_reuse;
 61         int reuseport = sk->sk_reuseport;
 62         kuid_t uid = sock_i_uid((struct sock *)sk);
 63 
 64         /*
 65          * Unlike other sk lookup places we do not check
 66          * for sk_net here, since _all_ the socks listed
 67          * in tb->owners list belong to the same net - the
 68          * one this bucket belongs to.
 69          */
 70 
 71         sk_for_each_bound(sk2, &tb->owners) {
 72                 if (sk != sk2 &&
 73                     !inet_v6_ipv6only(sk2) &&
 74                     (!sk->sk_bound_dev_if ||
 75                      !sk2->sk_bound_dev_if ||
 76                      sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
 77                         if ((!reuse || !sk2->sk_reuse ||
 78                             sk2->sk_state == TCP_LISTEN) &&
 79                             (!reuseport || !sk2->sk_reuseport ||
 80                             (sk2->sk_state != TCP_TIME_WAIT &&
 81                              !uid_eq(uid, sock_i_uid(sk2))))) {
 82                                 const __be32 sk2_rcv_saddr = sk_rcv_saddr(sk2);
 83                                 if (!sk2_rcv_saddr || !sk_rcv_saddr(sk) ||
 84                                     sk2_rcv_saddr == sk_rcv_saddr(sk))
 85                                         break;
 86                         }
 87                         if (!relax && reuse && sk2->sk_reuse &&
 88                             sk2->sk_state != TCP_LISTEN) {
 89                                 const __be32 sk2_rcv_saddr = sk_rcv_saddr(sk2);
 90 
 91                                 if (!sk2_rcv_saddr || !sk_rcv_saddr(sk) ||
 92                                     sk2_rcv_saddr == sk_rcv_saddr(sk))
 93                                         break;
 94                         }
 95                 }
 96         }
 97         return sk2 != NULL;
 98 }
 99 EXPORT_SYMBOL_GPL(inet_csk_bind_conflict);
100 
101 /* Obtain a reference to a local port for the given sock,
102  * if snum is zero it means select any available local port.
103  */
104 int inet_csk_get_port(struct sock *sk, unsigned short snum)
105 {
106         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
107         struct inet_bind_hashbucket *head;
108         struct inet_bind_bucket *tb;
109         int ret, attempts = 5;
110         struct net *net = sock_net(sk);
111         int smallest_size = -1, smallest_rover;
112         kuid_t uid = sock_i_uid(sk);
113 
114         local_bh_disable();
115         if (!snum) {
116                 int remaining, rover, low, high;
117 
118 again:
119                 inet_get_local_port_range(&low, &high);
120                 remaining = (high - low) + 1;
121                 smallest_rover = rover = net_random() % remaining + low;
122 
123                 smallest_size = -1;
124                 do {
125                         if (inet_is_reserved_local_port(rover))
126                                 goto next_nolock;
127                         head = &hashinfo->bhash[inet_bhashfn(net, rover,
128                                         hashinfo->bhash_size)];
129                         spin_lock(&head->lock);
130                         inet_bind_bucket_for_each(tb, &head->chain)
131                                 if (net_eq(ib_net(tb), net) && tb->port == rover) {
132                                         if (((tb->fastreuse > 0 &&
133                                               sk->sk_reuse &&
134                                               sk->sk_state != TCP_LISTEN) ||
135                                              (tb->fastreuseport > 0 &&
136                                               sk->sk_reuseport &&
137                                               uid_eq(tb->fastuid, uid))) &&
138                                             (tb->num_owners < smallest_size || smallest_size == -1)) {
139                                                 smallest_size = tb->num_owners;
140                                                 smallest_rover = rover;
141                                                 if (atomic_read(&hashinfo->bsockets) > (high - low) + 1 &&
142                                                     !inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb, false)) {
143                                                         snum = smallest_rover;
144                                                         goto tb_found;
145                                                 }
146                                         }
147                                         if (!inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb, false)) {
148                                                 snum = rover;
149                                                 goto tb_found;
150                                         }
151                                         goto next;
152                                 }
153                         break;
154                 next:
155                         spin_unlock(&head->lock);
156                 next_nolock:
157                         if (++rover > high)
158                                 rover = low;
159                 } while (--remaining > 0);
160 
161                 /* Exhausted local port range during search?  It is not
162                  * possible for us to be holding one of the bind hash
163                  * locks if this test triggers, because if 'remaining'
164                  * drops to zero, we broke out of the do/while loop at
165                  * the top level, not from the 'break;' statement.
166                  */
167                 ret = 1;
168                 if (remaining <= 0) {
169                         if (smallest_size != -1) {
170                                 snum = smallest_rover;
171                                 goto have_snum;
172                         }
173                         goto fail;
174                 }
175                 /* OK, here is the one we will use.  HEAD is
176                  * non-NULL and we hold it's mutex.
177                  */
178                 snum = rover;
179         } else {
180 have_snum:
181                 head = &hashinfo->bhash[inet_bhashfn(net, snum,
182                                 hashinfo->bhash_size)];
183                 spin_lock(&head->lock);
184                 inet_bind_bucket_for_each(tb, &head->chain)
185                         if (net_eq(ib_net(tb), net) && tb->port == snum)
186                                 goto tb_found;
187         }
188         tb = NULL;
189         goto tb_not_found;
190 tb_found:
191         if (!hlist_empty(&tb->owners)) {
192                 if (sk->sk_reuse == SK_FORCE_REUSE)
193                         goto success;
194 
195                 if (((tb->fastreuse > 0 &&
196                       sk->sk_reuse && sk->sk_state != TCP_LISTEN) ||
197                      (tb->fastreuseport > 0 &&
198                       sk->sk_reuseport && uid_eq(tb->fastuid, uid))) &&
199                     smallest_size == -1) {
200                         goto success;
201                 } else {
202                         ret = 1;
203                         if (inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb, true)) {
204                                 if (((sk->sk_reuse && sk->sk_state != TCP_LISTEN) ||
205                                      (tb->fastreuseport > 0 &&
206                                       sk->sk_reuseport && uid_eq(tb->fastuid, uid))) &&
207                                     smallest_size != -1 && --attempts >= 0) {
208                                         spin_unlock(&head->lock);
209                                         goto again;
210                                 }
211 
212                                 goto fail_unlock;
213                         }
214                 }
215         }
216 tb_not_found:
217         ret = 1;
218         if (!tb && (tb = inet_bind_bucket_create(hashinfo->bind_bucket_cachep,
219                                         net, head, snum)) == NULL)
220                 goto fail_unlock;
221         if (hlist_empty(&tb->owners)) {
222                 if (sk->sk_reuse && sk->sk_state != TCP_LISTEN)
223                         tb->fastreuse = 1;
224                 else
225                         tb->fastreuse = 0;
226                 if (sk->sk_reuseport) {
227                         tb->fastreuseport = 1;
228                         tb->fastuid = uid;
229                 } else
230                         tb->fastreuseport = 0;
231         } else {
232                 if (tb->fastreuse &&
233                     (!sk->sk_reuse || sk->sk_state == TCP_LISTEN))
234                         tb->fastreuse = 0;
235                 if (tb->fastreuseport &&
236                     (!sk->sk_reuseport || !uid_eq(tb->fastuid, uid)))
237                         tb->fastreuseport = 0;
238         }
239 success:
240         if (!inet_csk(sk)->icsk_bind_hash)
241                 inet_bind_hash(sk, tb, snum);
242         WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);
243         ret = 0;
244 
245 fail_unlock:
246         spin_unlock(&head->lock);
247 fail:
248         local_bh_enable();
249         return ret;
250 }
251 EXPORT_SYMBOL_GPL(inet_csk_get_port);
252 
253 /*
254  * Wait for an incoming connection, avoid race conditions. This must be called
255  * with the socket locked.
256  */
257 static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
258 {
259         struct inet_connection_sock *icsk = inet_csk(sk);
260         DEFINE_WAIT(wait);
261         int err;
262 
263         /*
264          * True wake-one mechanism for incoming connections: only
265          * one process gets woken up, not the 'whole herd'.
266          * Since we do not 'race & poll' for established sockets
267          * anymore, the common case will execute the loop only once.
268          *
269          * Subtle issue: "add_wait_queue_exclusive()" will be added
270          * after any current non-exclusive waiters, and we know that
271          * it will always _stay_ after any new non-exclusive waiters
272          * because all non-exclusive waiters are added at the
273          * beginning of the wait-queue. As such, it's ok to "drop"
274          * our exclusiveness temporarily when we get woken up without
275          * having to remove and re-insert us on the wait queue.
276          */
277         for (;;) {
278                 prepare_to_wait_exclusive(sk_sleep(sk), &wait,
279                                           TASK_INTERRUPTIBLE);
280                 release_sock(sk);
281                 if (reqsk_queue_empty(&icsk->icsk_accept_queue))
282                         timeo = schedule_timeout(timeo);
283                 lock_sock(sk);
284                 err = 0;
285                 if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
286                         break;
287                 err = -EINVAL;
288                 if (sk->sk_state != TCP_LISTEN)
289                         break;
290                 err = sock_intr_errno(timeo);
291                 if (signal_pending(current))
292                         break;
293                 err = -EAGAIN;
294                 if (!timeo)
295                         break;
296         }
297         finish_wait(sk_sleep(sk), &wait);
298         return err;
299 }
300 
301 /*
302  * This will accept the next outstanding connection.
303  */
304 struct sock *inet_csk_accept(struct sock *sk, int flags, int *err)
305 {
306         struct inet_connection_sock *icsk = inet_csk(sk);
307         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
308         struct sock *newsk;
309         struct request_sock *req;
310         int error;
311 
312         lock_sock(sk);
313 
314         /* We need to make sure that this socket is listening,
315          * and that it has something pending.
316          */
317         error = -EINVAL;
318         if (sk->sk_state != TCP_LISTEN)
319                 goto out_err;
320 
321         /* Find already established connection */
322         if (reqsk_queue_empty(queue)) {
323                 long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
324 
325                 /* If this is a non blocking socket don't sleep */
326                 error = -EAGAIN;
327                 if (!timeo)
328                         goto out_err;
329 
330                 error = inet_csk_wait_for_connect(sk, timeo);
331                 if (error)
332                         goto out_err;
333         }
334         req = reqsk_queue_remove(queue);
335         newsk = req->sk;
336 
337         sk_acceptq_removed(sk);
338         if (sk->sk_protocol == IPPROTO_TCP && queue->fastopenq != NULL) {
339                 spin_lock_bh(&queue->fastopenq->lock);
340                 if (tcp_rsk(req)->listener) {
341                         /* We are still waiting for the final ACK from 3WHS
342                          * so can't free req now. Instead, we set req->sk to
343                          * NULL to signify that the child socket is taken
344                          * so reqsk_fastopen_remove() will free the req
345                          * when 3WHS finishes (or is aborted).
346                          */
347                         req->sk = NULL;
348                         req = NULL;
349                 }
350                 spin_unlock_bh(&queue->fastopenq->lock);
351         }
352 out:
353         release_sock(sk);
354         if (req)
355                 __reqsk_free(req);
356         return newsk;
357 out_err:
358         newsk = NULL;
359         req = NULL;
360         *err = error;
361         goto out;
362 }
363 EXPORT_SYMBOL(inet_csk_accept);
364 
365 /*
366  * Using different timers for retransmit, delayed acks and probes
367  * We may wish use just one timer maintaining a list of expire jiffies
368  * to optimize.
369  */
370 void inet_csk_init_xmit_timers(struct sock *sk,
371                                void (*retransmit_handler)(unsigned long),
372                                void (*delack_handler)(unsigned long),
373                                void (*keepalive_handler)(unsigned long))
374 {
375         struct inet_connection_sock *icsk = inet_csk(sk);
376 
377         setup_timer(&icsk->icsk_retransmit_timer, retransmit_handler,
378                         (unsigned long)sk);
379         setup_timer(&icsk->icsk_delack_timer, delack_handler,
380                         (unsigned long)sk);
381         setup_timer(&sk->sk_timer, keepalive_handler, (unsigned long)sk);
382         icsk->icsk_pending = icsk->icsk_ack.pending = 0;
383 }
384 EXPORT_SYMBOL(inet_csk_init_xmit_timers);
385 
386 void inet_csk_clear_xmit_timers(struct sock *sk)
387 {
388         struct inet_connection_sock *icsk = inet_csk(sk);
389 
390         icsk->icsk_pending = icsk->icsk_ack.pending = icsk->icsk_ack.blocked = 0;
391 
392         sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
393         sk_stop_timer(sk, &icsk->icsk_delack_timer);
394         sk_stop_timer(sk, &sk->sk_timer);
395 }
396 EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
397 
398 void inet_csk_delete_keepalive_timer(struct sock *sk)
399 {
400         sk_stop_timer(sk, &sk->sk_timer);
401 }
402 EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
403 
404 void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
405 {
406         sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
407 }
408 EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
409 
410 struct dst_entry *inet_csk_route_req(struct sock *sk,
411                                      struct flowi4 *fl4,
412                                      const struct request_sock *req)
413 {
414         struct rtable *rt;
415         const struct inet_request_sock *ireq = inet_rsk(req);
416         struct ip_options_rcu *opt = inet_rsk(req)->opt;
417         struct net *net = sock_net(sk);
418         int flags = inet_sk_flowi_flags(sk);
419 
420         flowi4_init_output(fl4, sk->sk_bound_dev_if, sk->sk_mark,
421                            RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
422                            sk->sk_protocol,
423                            flags,
424                            (opt && opt->opt.srr) ? opt->opt.faddr : ireq->rmt_addr,
425                            ireq->loc_addr, ireq->rmt_port, inet_sk(sk)->inet_sport);
426         security_req_classify_flow(req, flowi4_to_flowi(fl4));
427         rt = ip_route_output_flow(net, fl4, sk);
428         if (IS_ERR(rt))
429                 goto no_route;
430         if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
431                 goto route_err;
432         return &rt->dst;
433 
434 route_err:
435         ip_rt_put(rt);
436 no_route:
437         IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES);
438         return NULL;
439 }
440 EXPORT_SYMBOL_GPL(inet_csk_route_req);
441 
442 struct dst_entry *inet_csk_route_child_sock(struct sock *sk,
443                                             struct sock *newsk,
444                                             const struct request_sock *req)
445 {
446         const struct inet_request_sock *ireq = inet_rsk(req);
447         struct inet_sock *newinet = inet_sk(newsk);
448         struct ip_options_rcu *opt;
449         struct net *net = sock_net(sk);
450         struct flowi4 *fl4;
451         struct rtable *rt;
452 
453         fl4 = &newinet->cork.fl.u.ip4;
454 
455         rcu_read_lock();
456         opt = rcu_dereference(newinet->inet_opt);
457         flowi4_init_output(fl4, sk->sk_bound_dev_if, sk->sk_mark,
458                            RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
459                            sk->sk_protocol, inet_sk_flowi_flags(sk),
460                            (opt && opt->opt.srr) ? opt->opt.faddr : ireq->rmt_addr,
461                            ireq->loc_addr, ireq->rmt_port, inet_sk(sk)->inet_sport);
462         security_req_classify_flow(req, flowi4_to_flowi(fl4));
463         rt = ip_route_output_flow(net, fl4, sk);
464         if (IS_ERR(rt))
465                 goto no_route;
466         if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
467                 goto route_err;
468         rcu_read_unlock();
469         return &rt->dst;
470 
471 route_err:
472         ip_rt_put(rt);
473 no_route:
474         rcu_read_unlock();
475         IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES);
476         return NULL;
477 }
478 EXPORT_SYMBOL_GPL(inet_csk_route_child_sock);
479 
480 static inline u32 inet_synq_hash(const __be32 raddr, const __be16 rport,
481                                  const u32 rnd, const u32 synq_hsize)
482 {
483         return jhash_2words((__force u32)raddr, (__force u32)rport, rnd) & (synq_hsize - 1);
484 }
485 
486 #if IS_ENABLED(CONFIG_IPV6)
487 #define AF_INET_FAMILY(fam) ((fam) == AF_INET)
488 #else
489 #define AF_INET_FAMILY(fam) 1
490 #endif
491 
492 struct request_sock *inet_csk_search_req(const struct sock *sk,
493                                          struct request_sock ***prevp,
494                                          const __be16 rport, const __be32 raddr,
495                                          const __be32 laddr)
496 {
497         const struct inet_connection_sock *icsk = inet_csk(sk);
498         struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
499         struct request_sock *req, **prev;
500 
501         for (prev = &lopt->syn_table[inet_synq_hash(raddr, rport, lopt->hash_rnd,
502                                                     lopt->nr_table_entries)];
503              (req = *prev) != NULL;
504              prev = &req->dl_next) {
505                 const struct inet_request_sock *ireq = inet_rsk(req);
506 
507                 if (ireq->rmt_port == rport &&
508                     ireq->rmt_addr == raddr &&
509                     ireq->loc_addr == laddr &&
510                     AF_INET_FAMILY(req->rsk_ops->family)) {
511                         WARN_ON(req->sk);
512                         *prevp = prev;
513                         break;
514                 }
515         }
516 
517         return req;
518 }
519 EXPORT_SYMBOL_GPL(inet_csk_search_req);
520 
521 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
522                                    unsigned long timeout)
523 {
524         struct inet_connection_sock *icsk = inet_csk(sk);
525         struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
526         const u32 h = inet_synq_hash(inet_rsk(req)->rmt_addr, inet_rsk(req)->rmt_port,
527                                      lopt->hash_rnd, lopt->nr_table_entries);
528 
529         reqsk_queue_hash_req(&icsk->icsk_accept_queue, h, req, timeout);
530         inet_csk_reqsk_queue_added(sk, timeout);
531 }
532 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
533 
534 /* Only thing we need from tcp.h */
535 extern int sysctl_tcp_synack_retries;
536 
537 
538 /* Decide when to expire the request and when to resend SYN-ACK */
539 static inline void syn_ack_recalc(struct request_sock *req, const int thresh,
540                                   const int max_retries,
541                                   const u8 rskq_defer_accept,
542                                   int *expire, int *resend)
543 {
544         if (!rskq_defer_accept) {
545                 *expire = req->num_timeout >= thresh;
546                 *resend = 1;
547                 return;
548         }
549         *expire = req->num_timeout >= thresh &&
550                   (!inet_rsk(req)->acked || req->num_timeout >= max_retries);
551         /*
552          * Do not resend while waiting for data after ACK,
553          * start to resend on end of deferring period to give
554          * last chance for data or ACK to create established socket.
555          */
556         *resend = !inet_rsk(req)->acked ||
557                   req->num_timeout >= rskq_defer_accept - 1;
558 }
559 
560 int inet_rtx_syn_ack(struct sock *parent, struct request_sock *req)
561 {
562         int err = req->rsk_ops->rtx_syn_ack(parent, req);
563 
564         if (!err)
565                 req->num_retrans++;
566         return err;
567 }
568 EXPORT_SYMBOL(inet_rtx_syn_ack);
569 
570 void inet_csk_reqsk_queue_prune(struct sock *parent,
571                                 const unsigned long interval,
572                                 const unsigned long timeout,
573                                 const unsigned long max_rto)
574 {
575         struct inet_connection_sock *icsk = inet_csk(parent);
576         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
577         struct listen_sock *lopt = queue->listen_opt;
578         int max_retries = icsk->icsk_syn_retries ? : sysctl_tcp_synack_retries;
579         int thresh = max_retries;
580         unsigned long now = jiffies;
581         struct request_sock **reqp, *req;
582         int i, budget;
583 
584         if (lopt == NULL || lopt->qlen == 0)
585                 return;
586 
587         /* Normally all the openreqs are young and become mature
588          * (i.e. converted to established socket) for first timeout.
589          * If synack was not acknowledged for 1 second, it means
590          * one of the following things: synack was lost, ack was lost,
591          * rtt is high or nobody planned to ack (i.e. synflood).
592          * When server is a bit loaded, queue is populated with old
593          * open requests, reducing effective size of queue.
594          * When server is well loaded, queue size reduces to zero
595          * after several minutes of work. It is not synflood,
596          * it is normal operation. The solution is pruning
597          * too old entries overriding normal timeout, when
598          * situation becomes dangerous.
599          *
600          * Essentially, we reserve half of room for young
601          * embrions; and abort old ones without pity, if old
602          * ones are about to clog our table.
603          */
604         if (lopt->qlen>>(lopt->max_qlen_log-1)) {
605                 int young = (lopt->qlen_young<<1);
606 
607                 while (thresh > 2) {
608                         if (lopt->qlen < young)
609                                 break;
610                         thresh--;
611                         young <<= 1;
612                 }
613         }
614 
615         if (queue->rskq_defer_accept)
616                 max_retries = queue->rskq_defer_accept;
617 
618         budget = 2 * (lopt->nr_table_entries / (timeout / interval));
619         i = lopt->clock_hand;
620 
621         do {
622                 reqp=&lopt->syn_table[i];
623                 while ((req = *reqp) != NULL) {
624                         if (time_after_eq(now, req->expires)) {
625                                 int expire = 0, resend = 0;
626 
627                                 syn_ack_recalc(req, thresh, max_retries,
628                                                queue->rskq_defer_accept,
629                                                &expire, &resend);
630                                 req->rsk_ops->syn_ack_timeout(parent, req);
631                                 if (!expire &&
632                                     (!resend ||
633                                      !inet_rtx_syn_ack(parent, req) ||
634                                      inet_rsk(req)->acked)) {
635                                         unsigned long timeo;
636 
637                                         if (req->num_timeout++ == 0)
638                                                 lopt->qlen_young--;
639                                         timeo = min(timeout << req->num_timeout,
640                                                     max_rto);
641                                         req->expires = now + timeo;
642                                         reqp = &req->dl_next;
643                                         continue;
644                                 }
645 
646                                 /* Drop this request */
647                                 inet_csk_reqsk_queue_unlink(parent, req, reqp);
648                                 reqsk_queue_removed(queue, req);
649                                 reqsk_free(req);
650                                 continue;
651                         }
652                         reqp = &req->dl_next;
653                 }
654 
655                 i = (i + 1) & (lopt->nr_table_entries - 1);
656 
657         } while (--budget > 0);
658 
659         lopt->clock_hand = i;
660 
661         if (lopt->qlen)
662                 inet_csk_reset_keepalive_timer(parent, interval);
663 }
664 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_prune);
665 
666 /**
667  *      inet_csk_clone_lock - clone an inet socket, and lock its clone
668  *      @sk: the socket to clone
669  *      @req: request_sock
670  *      @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
671  *
672  *      Caller must unlock socket even in error path (bh_unlock_sock(newsk))
673  */
674 struct sock *inet_csk_clone_lock(const struct sock *sk,
675                                  const struct request_sock *req,
676                                  const gfp_t priority)
677 {
678         struct sock *newsk = sk_clone_lock(sk, priority);
679 
680         if (newsk != NULL) {
681                 struct inet_connection_sock *newicsk = inet_csk(newsk);
682 
683                 newsk->sk_state = TCP_SYN_RECV;
684                 newicsk->icsk_bind_hash = NULL;
685 
686                 inet_sk(newsk)->inet_dport = inet_rsk(req)->rmt_port;
687                 inet_sk(newsk)->inet_num = ntohs(inet_rsk(req)->loc_port);
688                 inet_sk(newsk)->inet_sport = inet_rsk(req)->loc_port;
689                 newsk->sk_write_space = sk_stream_write_space;
690 
691                 newicsk->icsk_retransmits = 0;
692                 newicsk->icsk_backoff     = 0;
693                 newicsk->icsk_probes_out  = 0;
694 
695                 /* Deinitialize accept_queue to trap illegal accesses. */
696                 memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
697 
698                 security_inet_csk_clone(newsk, req);
699         }
700         return newsk;
701 }
702 EXPORT_SYMBOL_GPL(inet_csk_clone_lock);
703 
704 /*
705  * At this point, there should be no process reference to this
706  * socket, and thus no user references at all.  Therefore we
707  * can assume the socket waitqueue is inactive and nobody will
708  * try to jump onto it.
709  */
710 void inet_csk_destroy_sock(struct sock *sk)
711 {
712         WARN_ON(sk->sk_state != TCP_CLOSE);
713         WARN_ON(!sock_flag(sk, SOCK_DEAD));
714 
715         /* It cannot be in hash table! */
716         WARN_ON(!sk_unhashed(sk));
717 
718         /* If it has not 0 inet_sk(sk)->inet_num, it must be bound */
719         WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash);
720 
721         sk->sk_prot->destroy(sk);
722 
723         sk_stream_kill_queues(sk);
724 
725         xfrm_sk_free_policy(sk);
726 
727         sk_refcnt_debug_release(sk);
728 
729         percpu_counter_dec(sk->sk_prot->orphan_count);
730         sock_put(sk);
731 }
732 EXPORT_SYMBOL(inet_csk_destroy_sock);
733 
734 /* This function allows to force a closure of a socket after the call to
735  * tcp/dccp_create_openreq_child().
736  */
737 void inet_csk_prepare_forced_close(struct sock *sk)
738         __releases(&sk->sk_lock.slock)
739 {
740         /* sk_clone_lock locked the socket and set refcnt to 2 */
741         bh_unlock_sock(sk);
742         sock_put(sk);
743 
744         /* The below has to be done to allow calling inet_csk_destroy_sock */
745         sock_set_flag(sk, SOCK_DEAD);
746         percpu_counter_inc(sk->sk_prot->orphan_count);
747         inet_sk(sk)->inet_num = 0;
748 }
749 EXPORT_SYMBOL(inet_csk_prepare_forced_close);
750 
751 int inet_csk_listen_start(struct sock *sk, const int nr_table_entries)
752 {
753         struct inet_sock *inet = inet_sk(sk);
754         struct inet_connection_sock *icsk = inet_csk(sk);
755         int rc = reqsk_queue_alloc(&icsk->icsk_accept_queue, nr_table_entries);
756 
757         if (rc != 0)
758                 return rc;
759 
760         sk->sk_max_ack_backlog = 0;
761         sk->sk_ack_backlog = 0;
762         inet_csk_delack_init(sk);
763 
764         /* There is race window here: we announce ourselves listening,
765          * but this transition is still not validated by get_port().
766          * It is OK, because this socket enters to hash table only
767          * after validation is complete.
768          */
769         sk->sk_state = TCP_LISTEN;
770         if (!sk->sk_prot->get_port(sk, inet->inet_num)) {
771                 inet->inet_sport = htons(inet->inet_num);
772 
773                 sk_dst_reset(sk);
774                 sk->sk_prot->hash(sk);
775 
776                 return 0;
777         }
778 
779         sk->sk_state = TCP_CLOSE;
780         __reqsk_queue_destroy(&icsk->icsk_accept_queue);
781         return -EADDRINUSE;
782 }
783 EXPORT_SYMBOL_GPL(inet_csk_listen_start);
784 
785 /*
786  *      This routine closes sockets which have been at least partially
787  *      opened, but not yet accepted.
788  */
789 void inet_csk_listen_stop(struct sock *sk)
790 {
791         struct inet_connection_sock *icsk = inet_csk(sk);
792         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
793         struct request_sock *acc_req;
794         struct request_sock *req;
795 
796         inet_csk_delete_keepalive_timer(sk);
797 
798         /* make all the listen_opt local to us */
799         acc_req = reqsk_queue_yank_acceptq(queue);
800 
801         /* Following specs, it would be better either to send FIN
802          * (and enter FIN-WAIT-1, it is normal close)
803          * or to send active reset (abort).
804          * Certainly, it is pretty dangerous while synflood, but it is
805          * bad justification for our negligence 8)
806          * To be honest, we are not able to make either
807          * of the variants now.                 --ANK
808          */
809         reqsk_queue_destroy(queue);
810 
811         while ((req = acc_req) != NULL) {
812                 struct sock *child = req->sk;
813 
814                 acc_req = req->dl_next;
815 
816                 local_bh_disable();
817                 bh_lock_sock(child);
818                 WARN_ON(sock_owned_by_user(child));
819                 sock_hold(child);
820 
821                 sk->sk_prot->disconnect(child, O_NONBLOCK);
822 
823                 sock_orphan(child);
824 
825                 percpu_counter_inc(sk->sk_prot->orphan_count);
826 
827                 if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->listener) {
828                         BUG_ON(tcp_sk(child)->fastopen_rsk != req);
829                         BUG_ON(sk != tcp_rsk(req)->listener);
830 
831                         /* Paranoid, to prevent race condition if
832                          * an inbound pkt destined for child is
833                          * blocked by sock lock in tcp_v4_rcv().
834                          * Also to satisfy an assertion in
835                          * tcp_v4_destroy_sock().
836                          */
837                         tcp_sk(child)->fastopen_rsk = NULL;
838                         sock_put(sk);
839                 }
840                 inet_csk_destroy_sock(child);
841 
842                 bh_unlock_sock(child);
843                 local_bh_enable();
844                 sock_put(child);
845 
846                 sk_acceptq_removed(sk);
847                 __reqsk_free(req);
848         }
849         if (queue->fastopenq != NULL) {
850                 /* Free all the reqs queued in rskq_rst_head. */
851                 spin_lock_bh(&queue->fastopenq->lock);
852                 acc_req = queue->fastopenq->rskq_rst_head;
853                 queue->fastopenq->rskq_rst_head = NULL;
854                 spin_unlock_bh(&queue->fastopenq->lock);
855                 while ((req = acc_req) != NULL) {
856                         acc_req = req->dl_next;
857                         __reqsk_free(req);
858                 }
859         }
860         WARN_ON(sk->sk_ack_backlog);
861 }
862 EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
863 
864 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
865 {
866         struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
867         const struct inet_sock *inet = inet_sk(sk);
868 
869         sin->sin_family         = AF_INET;
870         sin->sin_addr.s_addr    = inet->inet_daddr;
871         sin->sin_port           = inet->inet_dport;
872 }
873 EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);
874 
875 #ifdef CONFIG_COMPAT
876 int inet_csk_compat_getsockopt(struct sock *sk, int level, int optname,
877                                char __user *optval, int __user *optlen)
878 {
879         const struct inet_connection_sock *icsk = inet_csk(sk);
880 
881         if (icsk->icsk_af_ops->compat_getsockopt != NULL)
882                 return icsk->icsk_af_ops->compat_getsockopt(sk, level, optname,
883                                                             optval, optlen);
884         return icsk->icsk_af_ops->getsockopt(sk, level, optname,
885                                              optval, optlen);
886 }
887 EXPORT_SYMBOL_GPL(inet_csk_compat_getsockopt);
888 
889 int inet_csk_compat_setsockopt(struct sock *sk, int level, int optname,
890                                char __user *optval, unsigned int optlen)
891 {
892         const struct inet_connection_sock *icsk = inet_csk(sk);
893 
894         if (icsk->icsk_af_ops->compat_setsockopt != NULL)
895                 return icsk->icsk_af_ops->compat_setsockopt(sk, level, optname,
896                                                             optval, optlen);
897         return icsk->icsk_af_ops->setsockopt(sk, level, optname,
898                                              optval, optlen);
899 }
900 EXPORT_SYMBOL_GPL(inet_csk_compat_setsockopt);
901 #endif
902 
903 static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *fl)
904 {
905         const struct inet_sock *inet = inet_sk(sk);
906         const struct ip_options_rcu *inet_opt;
907         __be32 daddr = inet->inet_daddr;
908         struct flowi4 *fl4;
909         struct rtable *rt;
910 
911         rcu_read_lock();
912         inet_opt = rcu_dereference(inet->inet_opt);
913         if (inet_opt && inet_opt->opt.srr)
914                 daddr = inet_opt->opt.faddr;
915         fl4 = &fl->u.ip4;
916         rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr,
917                                    inet->inet_saddr, inet->inet_dport,
918                                    inet->inet_sport, sk->sk_protocol,
919                                    RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
920         if (IS_ERR(rt))
921                 rt = NULL;
922         if (rt)
923                 sk_setup_caps(sk, &rt->dst);
924         rcu_read_unlock();
925 
926         return &rt->dst;
927 }
928 
929 struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu)
930 {
931         struct dst_entry *dst = __sk_dst_check(sk, 0);
932         struct inet_sock *inet = inet_sk(sk);
933 
934         if (!dst) {
935                 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
936                 if (!dst)
937                         goto out;
938         }
939         dst->ops->update_pmtu(dst, sk, NULL, mtu);
940 
941         dst = __sk_dst_check(sk, 0);
942         if (!dst)
943                 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
944 out:
945         return dst;
946 }
947 EXPORT_SYMBOL_GPL(inet_csk_update_pmtu);
948 

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