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TOMOYO Linux Cross Reference
Linux/net/sctp/associola.c

Version: ~ [ linux-5.5-rc7 ] ~ [ linux-5.4.13 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.97 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.166 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.210 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.210 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.81 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 /* SCTP kernel implementation
  2  * (C) Copyright IBM Corp. 2001, 2004
  3  * Copyright (c) 1999-2000 Cisco, Inc.
  4  * Copyright (c) 1999-2001 Motorola, Inc.
  5  * Copyright (c) 2001 Intel Corp.
  6  * Copyright (c) 2001 La Monte H.P. Yarroll
  7  *
  8  * This file is part of the SCTP kernel implementation
  9  *
 10  * This module provides the abstraction for an SCTP association.
 11  *
 12  * This SCTP implementation is free software;
 13  * you can redistribute it and/or modify it under the terms of
 14  * the GNU General Public License as published by
 15  * the Free Software Foundation; either version 2, or (at your option)
 16  * any later version.
 17  *
 18  * This SCTP implementation is distributed in the hope that it
 19  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
 20  *                 ************************
 21  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 22  * See the GNU General Public License for more details.
 23  *
 24  * You should have received a copy of the GNU General Public License
 25  * along with GNU CC; see the file COPYING.  If not, write to
 26  * the Free Software Foundation, 59 Temple Place - Suite 330,
 27  * Boston, MA 02111-1307, USA.
 28  *
 29  * Please send any bug reports or fixes you make to the
 30  * email address(es):
 31  *    lksctp developers <linux-sctp@vger.kernel.org>
 32  *
 33  * Written or modified by:
 34  *    La Monte H.P. Yarroll <piggy@acm.org>
 35  *    Karl Knutson          <karl@athena.chicago.il.us>
 36  *    Jon Grimm             <jgrimm@us.ibm.com>
 37  *    Xingang Guo           <xingang.guo@intel.com>
 38  *    Hui Huang             <hui.huang@nokia.com>
 39  *    Sridhar Samudrala     <sri@us.ibm.com>
 40  *    Daisy Chang           <daisyc@us.ibm.com>
 41  *    Ryan Layer            <rmlayer@us.ibm.com>
 42  *    Kevin Gao             <kevin.gao@intel.com>
 43  */
 44 
 45 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 46 
 47 #include <linux/types.h>
 48 #include <linux/fcntl.h>
 49 #include <linux/poll.h>
 50 #include <linux/init.h>
 51 
 52 #include <linux/slab.h>
 53 #include <linux/in.h>
 54 #include <net/ipv6.h>
 55 #include <net/sctp/sctp.h>
 56 #include <net/sctp/sm.h>
 57 
 58 /* Forward declarations for internal functions. */
 59 static void sctp_assoc_bh_rcv(struct work_struct *work);
 60 static void sctp_assoc_free_asconf_acks(struct sctp_association *asoc);
 61 static void sctp_assoc_free_asconf_queue(struct sctp_association *asoc);
 62 
 63 /* 1st Level Abstractions. */
 64 
 65 /* Initialize a new association from provided memory. */
 66 static struct sctp_association *sctp_association_init(struct sctp_association *asoc,
 67                                           const struct sctp_endpoint *ep,
 68                                           const struct sock *sk,
 69                                           sctp_scope_t scope,
 70                                           gfp_t gfp)
 71 {
 72         struct net *net = sock_net(sk);
 73         struct sctp_sock *sp;
 74         int i;
 75         sctp_paramhdr_t *p;
 76         int err;
 77 
 78         /* Retrieve the SCTP per socket area.  */
 79         sp = sctp_sk((struct sock *)sk);
 80 
 81         /* Discarding const is appropriate here.  */
 82         asoc->ep = (struct sctp_endpoint *)ep;
 83         asoc->base.sk = (struct sock *)sk;
 84 
 85         sctp_endpoint_hold(asoc->ep);
 86         sock_hold(asoc->base.sk);
 87 
 88         /* Initialize the common base substructure.  */
 89         asoc->base.type = SCTP_EP_TYPE_ASSOCIATION;
 90 
 91         /* Initialize the object handling fields.  */
 92         atomic_set(&asoc->base.refcnt, 1);
 93         asoc->base.dead = false;
 94 
 95         /* Initialize the bind addr area.  */
 96         sctp_bind_addr_init(&asoc->base.bind_addr, ep->base.bind_addr.port);
 97 
 98         asoc->state = SCTP_STATE_CLOSED;
 99         asoc->cookie_life = ms_to_ktime(sp->assocparams.sasoc_cookie_life);
100         asoc->frag_point = 0;
101         asoc->user_frag = sp->user_frag;
102 
103         /* Set the association max_retrans and RTO values from the
104          * socket values.
105          */
106         asoc->max_retrans = sp->assocparams.sasoc_asocmaxrxt;
107         asoc->pf_retrans  = net->sctp.pf_retrans;
108 
109         asoc->rto_initial = msecs_to_jiffies(sp->rtoinfo.srto_initial);
110         asoc->rto_max = msecs_to_jiffies(sp->rtoinfo.srto_max);
111         asoc->rto_min = msecs_to_jiffies(sp->rtoinfo.srto_min);
112 
113         asoc->overall_error_count = 0;
114 
115         /* Initialize the association's heartbeat interval based on the
116          * sock configured value.
117          */
118         asoc->hbinterval = msecs_to_jiffies(sp->hbinterval);
119 
120         /* Initialize path max retrans value. */
121         asoc->pathmaxrxt = sp->pathmaxrxt;
122 
123         /* Initialize default path MTU. */
124         asoc->pathmtu = sp->pathmtu;
125 
126         /* Set association default SACK delay */
127         asoc->sackdelay = msecs_to_jiffies(sp->sackdelay);
128         asoc->sackfreq = sp->sackfreq;
129 
130         /* Set the association default flags controlling
131          * Heartbeat, SACK delay, and Path MTU Discovery.
132          */
133         asoc->param_flags = sp->param_flags;
134 
135         /* Initialize the maximum mumber of new data packets that can be sent
136          * in a burst.
137          */
138         asoc->max_burst = sp->max_burst;
139 
140         /* initialize association timers */
141         asoc->timeouts[SCTP_EVENT_TIMEOUT_NONE] = 0;
142         asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_COOKIE] = asoc->rto_initial;
143         asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_INIT] = asoc->rto_initial;
144         asoc->timeouts[SCTP_EVENT_TIMEOUT_T2_SHUTDOWN] = asoc->rto_initial;
145         asoc->timeouts[SCTP_EVENT_TIMEOUT_T3_RTX] = 0;
146         asoc->timeouts[SCTP_EVENT_TIMEOUT_T4_RTO] = 0;
147 
148         /* sctpimpguide Section 2.12.2
149          * If the 'T5-shutdown-guard' timer is used, it SHOULD be set to the
150          * recommended value of 5 times 'RTO.Max'.
151          */
152         asoc->timeouts[SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]
153                 = 5 * asoc->rto_max;
154 
155         asoc->timeouts[SCTP_EVENT_TIMEOUT_HEARTBEAT] = 0;
156         asoc->timeouts[SCTP_EVENT_TIMEOUT_SACK] = asoc->sackdelay;
157         asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE] = sp->autoclose * HZ;
158 
159         /* Initializes the timers */
160         for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i)
161                 setup_timer(&asoc->timers[i], sctp_timer_events[i],
162                                 (unsigned long)asoc);
163 
164         /* Pull default initialization values from the sock options.
165          * Note: This assumes that the values have already been
166          * validated in the sock.
167          */
168         asoc->c.sinit_max_instreams = sp->initmsg.sinit_max_instreams;
169         asoc->c.sinit_num_ostreams  = sp->initmsg.sinit_num_ostreams;
170         asoc->max_init_attempts = sp->initmsg.sinit_max_attempts;
171 
172         asoc->max_init_timeo =
173                  msecs_to_jiffies(sp->initmsg.sinit_max_init_timeo);
174 
175         /* Allocate storage for the ssnmap after the inbound and outbound
176          * streams have been negotiated during Init.
177          */
178         asoc->ssnmap = NULL;
179 
180         /* Set the local window size for receive.
181          * This is also the rcvbuf space per association.
182          * RFC 6 - A SCTP receiver MUST be able to receive a minimum of
183          * 1500 bytes in one SCTP packet.
184          */
185         if ((sk->sk_rcvbuf/2) < SCTP_DEFAULT_MINWINDOW)
186                 asoc->rwnd = SCTP_DEFAULT_MINWINDOW;
187         else
188                 asoc->rwnd = sk->sk_rcvbuf/2;
189 
190         asoc->a_rwnd = asoc->rwnd;
191 
192         asoc->rwnd_over = 0;
193         asoc->rwnd_press = 0;
194 
195         /* Use my own max window until I learn something better.  */
196         asoc->peer.rwnd = SCTP_DEFAULT_MAXWINDOW;
197 
198         /* Set the sndbuf size for transmit.  */
199         asoc->sndbuf_used = 0;
200 
201         /* Initialize the receive memory counter */
202         atomic_set(&asoc->rmem_alloc, 0);
203 
204         init_waitqueue_head(&asoc->wait);
205 
206         asoc->c.my_vtag = sctp_generate_tag(ep);
207         asoc->peer.i.init_tag = 0;     /* INIT needs a vtag of 0. */
208         asoc->c.peer_vtag = 0;
209         asoc->c.my_ttag   = 0;
210         asoc->c.peer_ttag = 0;
211         asoc->c.my_port = ep->base.bind_addr.port;
212 
213         asoc->c.initial_tsn = sctp_generate_tsn(ep);
214 
215         asoc->next_tsn = asoc->c.initial_tsn;
216 
217         asoc->ctsn_ack_point = asoc->next_tsn - 1;
218         asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
219         asoc->highest_sacked = asoc->ctsn_ack_point;
220         asoc->last_cwr_tsn = asoc->ctsn_ack_point;
221         asoc->unack_data = 0;
222 
223         /* ADDIP Section 4.1 Asconf Chunk Procedures
224          *
225          * When an endpoint has an ASCONF signaled change to be sent to the
226          * remote endpoint it should do the following:
227          * ...
228          * A2) a serial number should be assigned to the chunk. The serial
229          * number SHOULD be a monotonically increasing number. The serial
230          * numbers SHOULD be initialized at the start of the
231          * association to the same value as the initial TSN.
232          */
233         asoc->addip_serial = asoc->c.initial_tsn;
234 
235         INIT_LIST_HEAD(&asoc->addip_chunk_list);
236         INIT_LIST_HEAD(&asoc->asconf_ack_list);
237 
238         /* Make an empty list of remote transport addresses.  */
239         INIT_LIST_HEAD(&asoc->peer.transport_addr_list);
240         asoc->peer.transport_count = 0;
241 
242         /* RFC 2960 5.1 Normal Establishment of an Association
243          *
244          * After the reception of the first data chunk in an
245          * association the endpoint must immediately respond with a
246          * sack to acknowledge the data chunk.  Subsequent
247          * acknowledgements should be done as described in Section
248          * 6.2.
249          *
250          * [We implement this by telling a new association that it
251          * already received one packet.]
252          */
253         asoc->peer.sack_needed = 1;
254         asoc->peer.sack_cnt = 0;
255         asoc->peer.sack_generation = 1;
256 
257         /* Assume that the peer will tell us if he recognizes ASCONF
258          * as part of INIT exchange.
259          * The sctp_addip_noauth option is there for backward compatibilty
260          * and will revert old behavior.
261          */
262         asoc->peer.asconf_capable = 0;
263         if (net->sctp.addip_noauth)
264                 asoc->peer.asconf_capable = 1;
265         asoc->asconf_addr_del_pending = NULL;
266         asoc->src_out_of_asoc_ok = 0;
267         asoc->new_transport = NULL;
268 
269         /* Create an input queue.  */
270         sctp_inq_init(&asoc->base.inqueue);
271         sctp_inq_set_th_handler(&asoc->base.inqueue, sctp_assoc_bh_rcv);
272 
273         /* Create an output queue.  */
274         sctp_outq_init(asoc, &asoc->outqueue);
275 
276         if (!sctp_ulpq_init(&asoc->ulpq, asoc))
277                 goto fail_init;
278 
279         memset(&asoc->peer.tsn_map, 0, sizeof(struct sctp_tsnmap));
280 
281         asoc->need_ecne = 0;
282 
283         asoc->assoc_id = 0;
284 
285         /* Assume that peer would support both address types unless we are
286          * told otherwise.
287          */
288         asoc->peer.ipv4_address = 1;
289         if (asoc->base.sk->sk_family == PF_INET6)
290                 asoc->peer.ipv6_address = 1;
291         INIT_LIST_HEAD(&asoc->asocs);
292 
293         asoc->default_stream = sp->default_stream;
294         asoc->default_ppid = sp->default_ppid;
295         asoc->default_flags = sp->default_flags;
296         asoc->default_context = sp->default_context;
297         asoc->default_timetolive = sp->default_timetolive;
298         asoc->default_rcv_context = sp->default_rcv_context;
299 
300         /* SCTP_GET_ASSOC_STATS COUNTERS */
301         memset(&asoc->stats, 0, sizeof(struct sctp_priv_assoc_stats));
302 
303         /* AUTH related initializations */
304         INIT_LIST_HEAD(&asoc->endpoint_shared_keys);
305         err = sctp_auth_asoc_copy_shkeys(ep, asoc, gfp);
306         if (err)
307                 goto fail_init;
308 
309         asoc->active_key_id = ep->active_key_id;
310         asoc->asoc_shared_key = NULL;
311 
312         asoc->default_hmac_id = 0;
313         /* Save the hmacs and chunks list into this association */
314         if (ep->auth_hmacs_list)
315                 memcpy(asoc->c.auth_hmacs, ep->auth_hmacs_list,
316                         ntohs(ep->auth_hmacs_list->param_hdr.length));
317         if (ep->auth_chunk_list)
318                 memcpy(asoc->c.auth_chunks, ep->auth_chunk_list,
319                         ntohs(ep->auth_chunk_list->param_hdr.length));
320 
321         /* Get the AUTH random number for this association */
322         p = (sctp_paramhdr_t *)asoc->c.auth_random;
323         p->type = SCTP_PARAM_RANDOM;
324         p->length = htons(sizeof(sctp_paramhdr_t) + SCTP_AUTH_RANDOM_LENGTH);
325         get_random_bytes(p+1, SCTP_AUTH_RANDOM_LENGTH);
326 
327         return asoc;
328 
329 fail_init:
330         sock_put(asoc->base.sk);
331         sctp_endpoint_put(asoc->ep);
332         return NULL;
333 }
334 
335 /* Allocate and initialize a new association */
336 struct sctp_association *sctp_association_new(const struct sctp_endpoint *ep,
337                                          const struct sock *sk,
338                                          sctp_scope_t scope,
339                                          gfp_t gfp)
340 {
341         struct sctp_association *asoc;
342 
343         asoc = kzalloc(sizeof(*asoc), gfp);
344         if (!asoc)
345                 goto fail;
346 
347         if (!sctp_association_init(asoc, ep, sk, scope, gfp))
348                 goto fail_init;
349 
350         SCTP_DBG_OBJCNT_INC(assoc);
351 
352         pr_debug("Created asoc %p\n", asoc);
353 
354         return asoc;
355 
356 fail_init:
357         kfree(asoc);
358 fail:
359         return NULL;
360 }
361 
362 /* Free this association if possible.  There may still be users, so
363  * the actual deallocation may be delayed.
364  */
365 void sctp_association_free(struct sctp_association *asoc)
366 {
367         struct sock *sk = asoc->base.sk;
368         struct sctp_transport *transport;
369         struct list_head *pos, *temp;
370         int i;
371 
372         /* Only real associations count against the endpoint, so
373          * don't bother for if this is a temporary association.
374          */
375         if (!asoc->temp) {
376                 list_del(&asoc->asocs);
377 
378                 /* Decrement the backlog value for a TCP-style listening
379                  * socket.
380                  */
381                 if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
382                         sk->sk_ack_backlog--;
383         }
384 
385         /* Mark as dead, so other users can know this structure is
386          * going away.
387          */
388         asoc->base.dead = true;
389 
390         /* Dispose of any data lying around in the outqueue. */
391         sctp_outq_free(&asoc->outqueue);
392 
393         /* Dispose of any pending messages for the upper layer. */
394         sctp_ulpq_free(&asoc->ulpq);
395 
396         /* Dispose of any pending chunks on the inqueue. */
397         sctp_inq_free(&asoc->base.inqueue);
398 
399         sctp_tsnmap_free(&asoc->peer.tsn_map);
400 
401         /* Free ssnmap storage. */
402         sctp_ssnmap_free(asoc->ssnmap);
403 
404         /* Clean up the bound address list. */
405         sctp_bind_addr_free(&asoc->base.bind_addr);
406 
407         /* Do we need to go through all of our timers and
408          * delete them?   To be safe we will try to delete all, but we
409          * should be able to go through and make a guess based
410          * on our state.
411          */
412         for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i) {
413                 if (del_timer(&asoc->timers[i]))
414                         sctp_association_put(asoc);
415         }
416 
417         /* Free peer's cached cookie. */
418         kfree(asoc->peer.cookie);
419         kfree(asoc->peer.peer_random);
420         kfree(asoc->peer.peer_chunks);
421         kfree(asoc->peer.peer_hmacs);
422 
423         /* Release the transport structures. */
424         list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
425                 transport = list_entry(pos, struct sctp_transport, transports);
426                 list_del_rcu(pos);
427                 sctp_transport_free(transport);
428         }
429 
430         asoc->peer.transport_count = 0;
431 
432         sctp_asconf_queue_teardown(asoc);
433 
434         /* Free pending address space being deleted */
435         if (asoc->asconf_addr_del_pending != NULL)
436                 kfree(asoc->asconf_addr_del_pending);
437 
438         /* AUTH - Free the endpoint shared keys */
439         sctp_auth_destroy_keys(&asoc->endpoint_shared_keys);
440 
441         /* AUTH - Free the association shared key */
442         sctp_auth_key_put(asoc->asoc_shared_key);
443 
444         sctp_association_put(asoc);
445 }
446 
447 /* Cleanup and free up an association. */
448 static void sctp_association_destroy(struct sctp_association *asoc)
449 {
450         if (unlikely(!asoc->base.dead)) {
451                 WARN(1, "Attempt to destroy undead association %p!\n", asoc);
452                 return;
453         }
454 
455         sctp_endpoint_put(asoc->ep);
456         sock_put(asoc->base.sk);
457 
458         if (asoc->assoc_id != 0) {
459                 spin_lock_bh(&sctp_assocs_id_lock);
460                 idr_remove(&sctp_assocs_id, asoc->assoc_id);
461                 spin_unlock_bh(&sctp_assocs_id_lock);
462         }
463 
464         WARN_ON(atomic_read(&asoc->rmem_alloc));
465 
466         kfree(asoc);
467         SCTP_DBG_OBJCNT_DEC(assoc);
468 }
469 
470 /* Change the primary destination address for the peer. */
471 void sctp_assoc_set_primary(struct sctp_association *asoc,
472                             struct sctp_transport *transport)
473 {
474         int changeover = 0;
475 
476         /* it's a changeover only if we already have a primary path
477          * that we are changing
478          */
479         if (asoc->peer.primary_path != NULL &&
480             asoc->peer.primary_path != transport)
481                 changeover = 1 ;
482 
483         asoc->peer.primary_path = transport;
484 
485         /* Set a default msg_name for events. */
486         memcpy(&asoc->peer.primary_addr, &transport->ipaddr,
487                sizeof(union sctp_addr));
488 
489         /* If the primary path is changing, assume that the
490          * user wants to use this new path.
491          */
492         if ((transport->state == SCTP_ACTIVE) ||
493             (transport->state == SCTP_UNKNOWN))
494                 asoc->peer.active_path = transport;
495 
496         /*
497          * SFR-CACC algorithm:
498          * Upon the receipt of a request to change the primary
499          * destination address, on the data structure for the new
500          * primary destination, the sender MUST do the following:
501          *
502          * 1) If CHANGEOVER_ACTIVE is set, then there was a switch
503          * to this destination address earlier. The sender MUST set
504          * CYCLING_CHANGEOVER to indicate that this switch is a
505          * double switch to the same destination address.
506          *
507          * Really, only bother is we have data queued or outstanding on
508          * the association.
509          */
510         if (!asoc->outqueue.outstanding_bytes && !asoc->outqueue.out_qlen)
511                 return;
512 
513         if (transport->cacc.changeover_active)
514                 transport->cacc.cycling_changeover = changeover;
515 
516         /* 2) The sender MUST set CHANGEOVER_ACTIVE to indicate that
517          * a changeover has occurred.
518          */
519         transport->cacc.changeover_active = changeover;
520 
521         /* 3) The sender MUST store the next TSN to be sent in
522          * next_tsn_at_change.
523          */
524         transport->cacc.next_tsn_at_change = asoc->next_tsn;
525 }
526 
527 /* Remove a transport from an association.  */
528 void sctp_assoc_rm_peer(struct sctp_association *asoc,
529                         struct sctp_transport *peer)
530 {
531         struct list_head        *pos;
532         struct sctp_transport   *transport;
533 
534         pr_debug("%s: association:%p addr:%pISpc\n",
535                  __func__, asoc, &peer->ipaddr.sa);
536 
537         /* If we are to remove the current retran_path, update it
538          * to the next peer before removing this peer from the list.
539          */
540         if (asoc->peer.retran_path == peer)
541                 sctp_assoc_update_retran_path(asoc);
542 
543         /* Remove this peer from the list. */
544         list_del_rcu(&peer->transports);
545 
546         /* Get the first transport of asoc. */
547         pos = asoc->peer.transport_addr_list.next;
548         transport = list_entry(pos, struct sctp_transport, transports);
549 
550         /* Update any entries that match the peer to be deleted. */
551         if (asoc->peer.primary_path == peer)
552                 sctp_assoc_set_primary(asoc, transport);
553         if (asoc->peer.active_path == peer)
554                 asoc->peer.active_path = transport;
555         if (asoc->peer.retran_path == peer)
556                 asoc->peer.retran_path = transport;
557         if (asoc->peer.last_data_from == peer)
558                 asoc->peer.last_data_from = transport;
559 
560         /* If we remove the transport an INIT was last sent to, set it to
561          * NULL. Combined with the update of the retran path above, this
562          * will cause the next INIT to be sent to the next available
563          * transport, maintaining the cycle.
564          */
565         if (asoc->init_last_sent_to == peer)
566                 asoc->init_last_sent_to = NULL;
567 
568         /* If we remove the transport an SHUTDOWN was last sent to, set it
569          * to NULL. Combined with the update of the retran path above, this
570          * will cause the next SHUTDOWN to be sent to the next available
571          * transport, maintaining the cycle.
572          */
573         if (asoc->shutdown_last_sent_to == peer)
574                 asoc->shutdown_last_sent_to = NULL;
575 
576         /* If we remove the transport an ASCONF was last sent to, set it to
577          * NULL.
578          */
579         if (asoc->addip_last_asconf &&
580             asoc->addip_last_asconf->transport == peer)
581                 asoc->addip_last_asconf->transport = NULL;
582 
583         /* If we have something on the transmitted list, we have to
584          * save it off.  The best place is the active path.
585          */
586         if (!list_empty(&peer->transmitted)) {
587                 struct sctp_transport *active = asoc->peer.active_path;
588                 struct sctp_chunk *ch;
589 
590                 /* Reset the transport of each chunk on this list */
591                 list_for_each_entry(ch, &peer->transmitted,
592                                         transmitted_list) {
593                         ch->transport = NULL;
594                         ch->rtt_in_progress = 0;
595                 }
596 
597                 list_splice_tail_init(&peer->transmitted,
598                                         &active->transmitted);
599 
600                 /* Start a T3 timer here in case it wasn't running so
601                  * that these migrated packets have a chance to get
602                  * retransmitted.
603                  */
604                 if (!timer_pending(&active->T3_rtx_timer))
605                         if (!mod_timer(&active->T3_rtx_timer,
606                                         jiffies + active->rto))
607                                 sctp_transport_hold(active);
608         }
609 
610         asoc->peer.transport_count--;
611 
612         sctp_transport_free(peer);
613 }
614 
615 /* Add a transport address to an association.  */
616 struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc,
617                                            const union sctp_addr *addr,
618                                            const gfp_t gfp,
619                                            const int peer_state)
620 {
621         struct net *net = sock_net(asoc->base.sk);
622         struct sctp_transport *peer;
623         struct sctp_sock *sp;
624         unsigned short port;
625 
626         sp = sctp_sk(asoc->base.sk);
627 
628         /* AF_INET and AF_INET6 share common port field. */
629         port = ntohs(addr->v4.sin_port);
630 
631         pr_debug("%s: association:%p addr:%pISpc state:%d\n", __func__,
632                  asoc, &addr->sa, peer_state);
633 
634         /* Set the port if it has not been set yet.  */
635         if (0 == asoc->peer.port)
636                 asoc->peer.port = port;
637 
638         /* Check to see if this is a duplicate. */
639         peer = sctp_assoc_lookup_paddr(asoc, addr);
640         if (peer) {
641                 /* An UNKNOWN state is only set on transports added by
642                  * user in sctp_connectx() call.  Such transports should be
643                  * considered CONFIRMED per RFC 4960, Section 5.4.
644                  */
645                 if (peer->state == SCTP_UNKNOWN) {
646                         peer->state = SCTP_ACTIVE;
647                 }
648                 return peer;
649         }
650 
651         peer = sctp_transport_new(net, addr, gfp);
652         if (!peer)
653                 return NULL;
654 
655         sctp_transport_set_owner(peer, asoc);
656 
657         /* Initialize the peer's heartbeat interval based on the
658          * association configured value.
659          */
660         peer->hbinterval = asoc->hbinterval;
661 
662         /* Set the path max_retrans.  */
663         peer->pathmaxrxt = asoc->pathmaxrxt;
664 
665         /* And the partial failure retrans threshold */
666         peer->pf_retrans = asoc->pf_retrans;
667 
668         /* Initialize the peer's SACK delay timeout based on the
669          * association configured value.
670          */
671         peer->sackdelay = asoc->sackdelay;
672         peer->sackfreq = asoc->sackfreq;
673 
674         /* Enable/disable heartbeat, SACK delay, and path MTU discovery
675          * based on association setting.
676          */
677         peer->param_flags = asoc->param_flags;
678 
679         sctp_transport_route(peer, NULL, sp);
680 
681         /* Initialize the pmtu of the transport. */
682         if (peer->param_flags & SPP_PMTUD_DISABLE) {
683                 if (asoc->pathmtu)
684                         peer->pathmtu = asoc->pathmtu;
685                 else
686                         peer->pathmtu = SCTP_DEFAULT_MAXSEGMENT;
687         }
688 
689         /* If this is the first transport addr on this association,
690          * initialize the association PMTU to the peer's PMTU.
691          * If not and the current association PMTU is higher than the new
692          * peer's PMTU, reset the association PMTU to the new peer's PMTU.
693          */
694         if (asoc->pathmtu)
695                 asoc->pathmtu = min_t(int, peer->pathmtu, asoc->pathmtu);
696         else
697                 asoc->pathmtu = peer->pathmtu;
698 
699         pr_debug("%s: association:%p PMTU set to %d\n", __func__, asoc,
700                  asoc->pathmtu);
701 
702         peer->pmtu_pending = 0;
703 
704         asoc->frag_point = sctp_frag_point(asoc, asoc->pathmtu);
705 
706         /* The asoc->peer.port might not be meaningful yet, but
707          * initialize the packet structure anyway.
708          */
709         sctp_packet_init(&peer->packet, peer, asoc->base.bind_addr.port,
710                          asoc->peer.port);
711 
712         /* 7.2.1 Slow-Start
713          *
714          * o The initial cwnd before DATA transmission or after a sufficiently
715          *   long idle period MUST be set to
716          *      min(4*MTU, max(2*MTU, 4380 bytes))
717          *
718          * o The initial value of ssthresh MAY be arbitrarily high
719          *   (for example, implementations MAY use the size of the
720          *   receiver advertised window).
721          */
722         peer->cwnd = min(4*asoc->pathmtu, max_t(__u32, 2*asoc->pathmtu, 4380));
723 
724         /* At this point, we may not have the receiver's advertised window,
725          * so initialize ssthresh to the default value and it will be set
726          * later when we process the INIT.
727          */
728         peer->ssthresh = SCTP_DEFAULT_MAXWINDOW;
729 
730         peer->partial_bytes_acked = 0;
731         peer->flight_size = 0;
732         peer->burst_limited = 0;
733 
734         /* Set the transport's RTO.initial value */
735         peer->rto = asoc->rto_initial;
736         sctp_max_rto(asoc, peer);
737 
738         /* Set the peer's active state. */
739         peer->state = peer_state;
740 
741         /* Attach the remote transport to our asoc.  */
742         list_add_tail_rcu(&peer->transports, &asoc->peer.transport_addr_list);
743         asoc->peer.transport_count++;
744 
745         /* If we do not yet have a primary path, set one.  */
746         if (!asoc->peer.primary_path) {
747                 sctp_assoc_set_primary(asoc, peer);
748                 asoc->peer.retran_path = peer;
749         }
750 
751         if (asoc->peer.active_path == asoc->peer.retran_path &&
752             peer->state != SCTP_UNCONFIRMED) {
753                 asoc->peer.retran_path = peer;
754         }
755 
756         return peer;
757 }
758 
759 /* Delete a transport address from an association.  */
760 void sctp_assoc_del_peer(struct sctp_association *asoc,
761                          const union sctp_addr *addr)
762 {
763         struct list_head        *pos;
764         struct list_head        *temp;
765         struct sctp_transport   *transport;
766 
767         list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
768                 transport = list_entry(pos, struct sctp_transport, transports);
769                 if (sctp_cmp_addr_exact(addr, &transport->ipaddr)) {
770                         /* Do book keeping for removing the peer and free it. */
771                         sctp_assoc_rm_peer(asoc, transport);
772                         break;
773                 }
774         }
775 }
776 
777 /* Lookup a transport by address. */
778 struct sctp_transport *sctp_assoc_lookup_paddr(
779                                         const struct sctp_association *asoc,
780                                         const union sctp_addr *address)
781 {
782         struct sctp_transport *t;
783 
784         /* Cycle through all transports searching for a peer address. */
785 
786         list_for_each_entry(t, &asoc->peer.transport_addr_list,
787                         transports) {
788                 if (sctp_cmp_addr_exact(address, &t->ipaddr))
789                         return t;
790         }
791 
792         return NULL;
793 }
794 
795 /* Remove all transports except a give one */
796 void sctp_assoc_del_nonprimary_peers(struct sctp_association *asoc,
797                                      struct sctp_transport *primary)
798 {
799         struct sctp_transport   *temp;
800         struct sctp_transport   *t;
801 
802         list_for_each_entry_safe(t, temp, &asoc->peer.transport_addr_list,
803                                  transports) {
804                 /* if the current transport is not the primary one, delete it */
805                 if (t != primary)
806                         sctp_assoc_rm_peer(asoc, t);
807         }
808 }
809 
810 /* Engage in transport control operations.
811  * Mark the transport up or down and send a notification to the user.
812  * Select and update the new active and retran paths.
813  */
814 void sctp_assoc_control_transport(struct sctp_association *asoc,
815                                   struct sctp_transport *transport,
816                                   sctp_transport_cmd_t command,
817                                   sctp_sn_error_t error)
818 {
819         struct sctp_transport *t = NULL;
820         struct sctp_transport *first;
821         struct sctp_transport *second;
822         struct sctp_ulpevent *event;
823         struct sockaddr_storage addr;
824         int spc_state = 0;
825         bool ulp_notify = true;
826 
827         /* Record the transition on the transport.  */
828         switch (command) {
829         case SCTP_TRANSPORT_UP:
830                 /* If we are moving from UNCONFIRMED state due
831                  * to heartbeat success, report the SCTP_ADDR_CONFIRMED
832                  * state to the user, otherwise report SCTP_ADDR_AVAILABLE.
833                  */
834                 if (SCTP_UNCONFIRMED == transport->state &&
835                     SCTP_HEARTBEAT_SUCCESS == error)
836                         spc_state = SCTP_ADDR_CONFIRMED;
837                 else
838                         spc_state = SCTP_ADDR_AVAILABLE;
839                 /* Don't inform ULP about transition from PF to
840                  * active state and set cwnd to 1 MTU, see SCTP
841                  * Quick failover draft section 5.1, point 5
842                  */
843                 if (transport->state == SCTP_PF) {
844                         ulp_notify = false;
845                         transport->cwnd = asoc->pathmtu;
846                 }
847                 transport->state = SCTP_ACTIVE;
848                 break;
849 
850         case SCTP_TRANSPORT_DOWN:
851                 /* If the transport was never confirmed, do not transition it
852                  * to inactive state.  Also, release the cached route since
853                  * there may be a better route next time.
854                  */
855                 if (transport->state != SCTP_UNCONFIRMED)
856                         transport->state = SCTP_INACTIVE;
857                 else {
858                         dst_release(transport->dst);
859                         transport->dst = NULL;
860                 }
861 
862                 spc_state = SCTP_ADDR_UNREACHABLE;
863                 break;
864 
865         case SCTP_TRANSPORT_PF:
866                 transport->state = SCTP_PF;
867                 ulp_notify = false;
868                 break;
869 
870         default:
871                 return;
872         }
873 
874         /* Generate and send a SCTP_PEER_ADDR_CHANGE notification to the
875          * user.
876          */
877         if (ulp_notify) {
878                 memset(&addr, 0, sizeof(struct sockaddr_storage));
879                 memcpy(&addr, &transport->ipaddr,
880                        transport->af_specific->sockaddr_len);
881                 event = sctp_ulpevent_make_peer_addr_change(asoc, &addr,
882                                         0, spc_state, error, GFP_ATOMIC);
883                 if (event)
884                         sctp_ulpq_tail_event(&asoc->ulpq, event);
885         }
886 
887         /* Select new active and retran paths. */
888 
889         /* Look for the two most recently used active transports.
890          *
891          * This code produces the wrong ordering whenever jiffies
892          * rolls over, but we still get usable transports, so we don't
893          * worry about it.
894          */
895         first = NULL; second = NULL;
896 
897         list_for_each_entry(t, &asoc->peer.transport_addr_list,
898                         transports) {
899 
900                 if ((t->state == SCTP_INACTIVE) ||
901                     (t->state == SCTP_UNCONFIRMED) ||
902                     (t->state == SCTP_PF))
903                         continue;
904                 if (!first || t->last_time_heard > first->last_time_heard) {
905                         second = first;
906                         first = t;
907                 } else if (!second ||
908                            t->last_time_heard > second->last_time_heard)
909                         second = t;
910         }
911 
912         /* RFC 2960 6.4 Multi-Homed SCTP Endpoints
913          *
914          * By default, an endpoint should always transmit to the
915          * primary path, unless the SCTP user explicitly specifies the
916          * destination transport address (and possibly source
917          * transport address) to use.
918          *
919          * [If the primary is active but not most recent, bump the most
920          * recently used transport.]
921          */
922         if (((asoc->peer.primary_path->state == SCTP_ACTIVE) ||
923              (asoc->peer.primary_path->state == SCTP_UNKNOWN)) &&
924             first != asoc->peer.primary_path) {
925                 second = first;
926                 first = asoc->peer.primary_path;
927         }
928 
929         if (!second)
930                 second = first;
931         /* If we failed to find a usable transport, just camp on the
932          * primary, even if it is inactive.
933          */
934         if (!first) {
935                 first = asoc->peer.primary_path;
936                 second = asoc->peer.primary_path;
937         }
938 
939         /* Set the active and retran transports.  */
940         asoc->peer.active_path = first;
941         asoc->peer.retran_path = second;
942 }
943 
944 /* Hold a reference to an association. */
945 void sctp_association_hold(struct sctp_association *asoc)
946 {
947         atomic_inc(&asoc->base.refcnt);
948 }
949 
950 /* Release a reference to an association and cleanup
951  * if there are no more references.
952  */
953 void sctp_association_put(struct sctp_association *asoc)
954 {
955         if (atomic_dec_and_test(&asoc->base.refcnt))
956                 sctp_association_destroy(asoc);
957 }
958 
959 /* Allocate the next TSN, Transmission Sequence Number, for the given
960  * association.
961  */
962 __u32 sctp_association_get_next_tsn(struct sctp_association *asoc)
963 {
964         /* From Section 1.6 Serial Number Arithmetic:
965          * Transmission Sequence Numbers wrap around when they reach
966          * 2**32 - 1.  That is, the next TSN a DATA chunk MUST use
967          * after transmitting TSN = 2*32 - 1 is TSN = 0.
968          */
969         __u32 retval = asoc->next_tsn;
970         asoc->next_tsn++;
971         asoc->unack_data++;
972 
973         return retval;
974 }
975 
976 /* Compare two addresses to see if they match.  Wildcard addresses
977  * only match themselves.
978  */
979 int sctp_cmp_addr_exact(const union sctp_addr *ss1,
980                         const union sctp_addr *ss2)
981 {
982         struct sctp_af *af;
983 
984         af = sctp_get_af_specific(ss1->sa.sa_family);
985         if (unlikely(!af))
986                 return 0;
987 
988         return af->cmp_addr(ss1, ss2);
989 }
990 
991 /* Return an ecne chunk to get prepended to a packet.
992  * Note:  We are sly and return a shared, prealloced chunk.  FIXME:
993  * No we don't, but we could/should.
994  */
995 struct sctp_chunk *sctp_get_ecne_prepend(struct sctp_association *asoc)
996 {
997         struct sctp_chunk *chunk;
998 
999         /* Send ECNE if needed.
1000          * Not being able to allocate a chunk here is not deadly.
1001          */
1002         if (asoc->need_ecne)
1003                 chunk = sctp_make_ecne(asoc, asoc->last_ecne_tsn);
1004         else
1005                 chunk = NULL;
1006 
1007         return chunk;
1008 }
1009 
1010 /*
1011  * Find which transport this TSN was sent on.
1012  */
1013 struct sctp_transport *sctp_assoc_lookup_tsn(struct sctp_association *asoc,
1014                                              __u32 tsn)
1015 {
1016         struct sctp_transport *active;
1017         struct sctp_transport *match;
1018         struct sctp_transport *transport;
1019         struct sctp_chunk *chunk;
1020         __be32 key = htonl(tsn);
1021 
1022         match = NULL;
1023 
1024         /*
1025          * FIXME: In general, find a more efficient data structure for
1026          * searching.
1027          */
1028 
1029         /*
1030          * The general strategy is to search each transport's transmitted
1031          * list.   Return which transport this TSN lives on.
1032          *
1033          * Let's be hopeful and check the active_path first.
1034          * Another optimization would be to know if there is only one
1035          * outbound path and not have to look for the TSN at all.
1036          *
1037          */
1038 
1039         active = asoc->peer.active_path;
1040 
1041         list_for_each_entry(chunk, &active->transmitted,
1042                         transmitted_list) {
1043 
1044                 if (key == chunk->subh.data_hdr->tsn) {
1045                         match = active;
1046                         goto out;
1047                 }
1048         }
1049 
1050         /* If not found, go search all the other transports. */
1051         list_for_each_entry(transport, &asoc->peer.transport_addr_list,
1052                         transports) {
1053 
1054                 if (transport == active)
1055                         continue;
1056                 list_for_each_entry(chunk, &transport->transmitted,
1057                                 transmitted_list) {
1058                         if (key == chunk->subh.data_hdr->tsn) {
1059                                 match = transport;
1060                                 goto out;
1061                         }
1062                 }
1063         }
1064 out:
1065         return match;
1066 }
1067 
1068 /* Is this the association we are looking for? */
1069 struct sctp_transport *sctp_assoc_is_match(struct sctp_association *asoc,
1070                                            struct net *net,
1071                                            const union sctp_addr *laddr,
1072                                            const union sctp_addr *paddr)
1073 {
1074         struct sctp_transport *transport;
1075 
1076         if ((htons(asoc->base.bind_addr.port) == laddr->v4.sin_port) &&
1077             (htons(asoc->peer.port) == paddr->v4.sin_port) &&
1078             net_eq(sock_net(asoc->base.sk), net)) {
1079                 transport = sctp_assoc_lookup_paddr(asoc, paddr);
1080                 if (!transport)
1081                         goto out;
1082 
1083                 if (sctp_bind_addr_match(&asoc->base.bind_addr, laddr,
1084                                          sctp_sk(asoc->base.sk)))
1085                         goto out;
1086         }
1087         transport = NULL;
1088 
1089 out:
1090         return transport;
1091 }
1092 
1093 /* Do delayed input processing.  This is scheduled by sctp_rcv(). */
1094 static void sctp_assoc_bh_rcv(struct work_struct *work)
1095 {
1096         struct sctp_association *asoc =
1097                 container_of(work, struct sctp_association,
1098                              base.inqueue.immediate);
1099         struct net *net = sock_net(asoc->base.sk);
1100         struct sctp_endpoint *ep;
1101         struct sctp_chunk *chunk;
1102         struct sctp_inq *inqueue;
1103         int state;
1104         sctp_subtype_t subtype;
1105         int error = 0;
1106 
1107         /* The association should be held so we should be safe. */
1108         ep = asoc->ep;
1109 
1110         inqueue = &asoc->base.inqueue;
1111         sctp_association_hold(asoc);
1112         while (NULL != (chunk = sctp_inq_pop(inqueue))) {
1113                 state = asoc->state;
1114                 subtype = SCTP_ST_CHUNK(chunk->chunk_hdr->type);
1115 
1116                 /* SCTP-AUTH, Section 6.3:
1117                  *    The receiver has a list of chunk types which it expects
1118                  *    to be received only after an AUTH-chunk.  This list has
1119                  *    been sent to the peer during the association setup.  It
1120                  *    MUST silently discard these chunks if they are not placed
1121                  *    after an AUTH chunk in the packet.
1122                  */
1123                 if (sctp_auth_recv_cid(subtype.chunk, asoc) && !chunk->auth)
1124                         continue;
1125 
1126                 /* Remember where the last DATA chunk came from so we
1127                  * know where to send the SACK.
1128                  */
1129                 if (sctp_chunk_is_data(chunk))
1130                         asoc->peer.last_data_from = chunk->transport;
1131                 else {
1132                         SCTP_INC_STATS(net, SCTP_MIB_INCTRLCHUNKS);
1133                         asoc->stats.ictrlchunks++;
1134                         if (chunk->chunk_hdr->type == SCTP_CID_SACK)
1135                                 asoc->stats.isacks++;
1136                 }
1137 
1138                 if (chunk->transport)
1139                         chunk->transport->last_time_heard = jiffies;
1140 
1141                 /* Run through the state machine. */
1142                 error = sctp_do_sm(net, SCTP_EVENT_T_CHUNK, subtype,
1143                                    state, ep, asoc, chunk, GFP_ATOMIC);
1144 
1145                 /* Check to see if the association is freed in response to
1146                  * the incoming chunk.  If so, get out of the while loop.
1147                  */
1148                 if (asoc->base.dead)
1149                         break;
1150 
1151                 /* If there is an error on chunk, discard this packet. */
1152                 if (error && chunk)
1153                         chunk->pdiscard = 1;
1154         }
1155         sctp_association_put(asoc);
1156 }
1157 
1158 /* This routine moves an association from its old sk to a new sk.  */
1159 void sctp_assoc_migrate(struct sctp_association *assoc, struct sock *newsk)
1160 {
1161         struct sctp_sock *newsp = sctp_sk(newsk);
1162         struct sock *oldsk = assoc->base.sk;
1163 
1164         /* Delete the association from the old endpoint's list of
1165          * associations.
1166          */
1167         list_del_init(&assoc->asocs);
1168 
1169         /* Decrement the backlog value for a TCP-style socket. */
1170         if (sctp_style(oldsk, TCP))
1171                 oldsk->sk_ack_backlog--;
1172 
1173         /* Release references to the old endpoint and the sock.  */
1174         sctp_endpoint_put(assoc->ep);
1175         sock_put(assoc->base.sk);
1176 
1177         /* Get a reference to the new endpoint.  */
1178         assoc->ep = newsp->ep;
1179         sctp_endpoint_hold(assoc->ep);
1180 
1181         /* Get a reference to the new sock.  */
1182         assoc->base.sk = newsk;
1183         sock_hold(assoc->base.sk);
1184 
1185         /* Add the association to the new endpoint's list of associations.  */
1186         sctp_endpoint_add_asoc(newsp->ep, assoc);
1187 }
1188 
1189 /* Update an association (possibly from unexpected COOKIE-ECHO processing).  */
1190 void sctp_assoc_update(struct sctp_association *asoc,
1191                        struct sctp_association *new)
1192 {
1193         struct sctp_transport *trans;
1194         struct list_head *pos, *temp;
1195 
1196         /* Copy in new parameters of peer. */
1197         asoc->c = new->c;
1198         asoc->peer.rwnd = new->peer.rwnd;
1199         asoc->peer.sack_needed = new->peer.sack_needed;
1200         asoc->peer.i = new->peer.i;
1201         sctp_tsnmap_init(&asoc->peer.tsn_map, SCTP_TSN_MAP_INITIAL,
1202                          asoc->peer.i.initial_tsn, GFP_ATOMIC);
1203 
1204         /* Remove any peer addresses not present in the new association. */
1205         list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
1206                 trans = list_entry(pos, struct sctp_transport, transports);
1207                 if (!sctp_assoc_lookup_paddr(new, &trans->ipaddr)) {
1208                         sctp_assoc_rm_peer(asoc, trans);
1209                         continue;
1210                 }
1211 
1212                 if (asoc->state >= SCTP_STATE_ESTABLISHED)
1213                         sctp_transport_reset(trans);
1214         }
1215 
1216         /* If the case is A (association restart), use
1217          * initial_tsn as next_tsn. If the case is B, use
1218          * current next_tsn in case data sent to peer
1219          * has been discarded and needs retransmission.
1220          */
1221         if (asoc->state >= SCTP_STATE_ESTABLISHED) {
1222                 asoc->next_tsn = new->next_tsn;
1223                 asoc->ctsn_ack_point = new->ctsn_ack_point;
1224                 asoc->adv_peer_ack_point = new->adv_peer_ack_point;
1225 
1226                 /* Reinitialize SSN for both local streams
1227                  * and peer's streams.
1228                  */
1229                 sctp_ssnmap_clear(asoc->ssnmap);
1230 
1231                 /* Flush the ULP reassembly and ordered queue.
1232                  * Any data there will now be stale and will
1233                  * cause problems.
1234                  */
1235                 sctp_ulpq_flush(&asoc->ulpq);
1236 
1237                 /* reset the overall association error count so
1238                  * that the restarted association doesn't get torn
1239                  * down on the next retransmission timer.
1240                  */
1241                 asoc->overall_error_count = 0;
1242 
1243         } else {
1244                 /* Add any peer addresses from the new association. */
1245                 list_for_each_entry(trans, &new->peer.transport_addr_list,
1246                                 transports) {
1247                         if (!sctp_assoc_lookup_paddr(asoc, &trans->ipaddr))
1248                                 sctp_assoc_add_peer(asoc, &trans->ipaddr,
1249                                                     GFP_ATOMIC, trans->state);
1250                 }
1251 
1252                 asoc->ctsn_ack_point = asoc->next_tsn - 1;
1253                 asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
1254                 if (!asoc->ssnmap) {
1255                         /* Move the ssnmap. */
1256                         asoc->ssnmap = new->ssnmap;
1257                         new->ssnmap = NULL;
1258                 }
1259 
1260                 if (!asoc->assoc_id) {
1261                         /* get a new association id since we don't have one
1262                          * yet.
1263                          */
1264                         sctp_assoc_set_id(asoc, GFP_ATOMIC);
1265                 }
1266         }
1267 
1268         /* SCTP-AUTH: Save the peer parameters from the new assocaitions
1269          * and also move the association shared keys over
1270          */
1271         kfree(asoc->peer.peer_random);
1272         asoc->peer.peer_random = new->peer.peer_random;
1273         new->peer.peer_random = NULL;
1274 
1275         kfree(asoc->peer.peer_chunks);
1276         asoc->peer.peer_chunks = new->peer.peer_chunks;
1277         new->peer.peer_chunks = NULL;
1278 
1279         kfree(asoc->peer.peer_hmacs);
1280         asoc->peer.peer_hmacs = new->peer.peer_hmacs;
1281         new->peer.peer_hmacs = NULL;
1282 
1283         sctp_auth_key_put(asoc->asoc_shared_key);
1284         sctp_auth_asoc_init_active_key(asoc, GFP_ATOMIC);
1285 }
1286 
1287 /* Update the retran path for sending a retransmitted packet.
1288  * Round-robin through the active transports, else round-robin
1289  * through the inactive transports as this is the next best thing
1290  * we can try.
1291  */
1292 void sctp_assoc_update_retran_path(struct sctp_association *asoc)
1293 {
1294         struct sctp_transport *t, *next;
1295         struct list_head *head = &asoc->peer.transport_addr_list;
1296         struct list_head *pos;
1297 
1298         if (asoc->peer.transport_count == 1)
1299                 return;
1300 
1301         /* Find the next transport in a round-robin fashion. */
1302         t = asoc->peer.retran_path;
1303         pos = &t->transports;
1304         next = NULL;
1305 
1306         while (1) {
1307                 /* Skip the head. */
1308                 if (pos->next == head)
1309                         pos = head->next;
1310                 else
1311                         pos = pos->next;
1312 
1313                 t = list_entry(pos, struct sctp_transport, transports);
1314 
1315                 /* We have exhausted the list, but didn't find any
1316                  * other active transports.  If so, use the next
1317                  * transport.
1318                  */
1319                 if (t == asoc->peer.retran_path) {
1320                         t = next;
1321                         break;
1322                 }
1323 
1324                 /* Try to find an active transport. */
1325 
1326                 if ((t->state == SCTP_ACTIVE) ||
1327                     (t->state == SCTP_UNKNOWN)) {
1328                         break;
1329                 } else {
1330                         /* Keep track of the next transport in case
1331                          * we don't find any active transport.
1332                          */
1333                         if (t->state != SCTP_UNCONFIRMED && !next)
1334                                 next = t;
1335                 }
1336         }
1337 
1338         if (t)
1339                 asoc->peer.retran_path = t;
1340         else
1341                 t = asoc->peer.retran_path;
1342 
1343         pr_debug("%s: association:%p addr:%pISpc\n", __func__, asoc,
1344                  &t->ipaddr.sa);
1345 }
1346 
1347 /* Choose the transport for sending retransmit packet.  */
1348 struct sctp_transport *sctp_assoc_choose_alter_transport(
1349         struct sctp_association *asoc, struct sctp_transport *last_sent_to)
1350 {
1351         /* If this is the first time packet is sent, use the active path,
1352          * else use the retran path. If the last packet was sent over the
1353          * retran path, update the retran path and use it.
1354          */
1355         if (!last_sent_to)
1356                 return asoc->peer.active_path;
1357         else {
1358                 if (last_sent_to == asoc->peer.retran_path)
1359                         sctp_assoc_update_retran_path(asoc);
1360                 return asoc->peer.retran_path;
1361         }
1362 }
1363 
1364 /* Update the association's pmtu and frag_point by going through all the
1365  * transports. This routine is called when a transport's PMTU has changed.
1366  */
1367 void sctp_assoc_sync_pmtu(struct sock *sk, struct sctp_association *asoc)
1368 {
1369         struct sctp_transport *t;
1370         __u32 pmtu = 0;
1371 
1372         if (!asoc)
1373                 return;
1374 
1375         /* Get the lowest pmtu of all the transports. */
1376         list_for_each_entry(t, &asoc->peer.transport_addr_list,
1377                                 transports) {
1378                 if (t->pmtu_pending && t->dst) {
1379                         sctp_transport_update_pmtu(sk, t, dst_mtu(t->dst));
1380                         t->pmtu_pending = 0;
1381                 }
1382                 if (!pmtu || (t->pathmtu < pmtu))
1383                         pmtu = t->pathmtu;
1384         }
1385 
1386         if (pmtu) {
1387                 asoc->pathmtu = pmtu;
1388                 asoc->frag_point = sctp_frag_point(asoc, pmtu);
1389         }
1390 
1391         pr_debug("%s: asoc:%p, pmtu:%d, frag_point:%d\n", __func__, asoc,
1392                  asoc->pathmtu, asoc->frag_point);
1393 }
1394 
1395 /* Should we send a SACK to update our peer? */
1396 static inline int sctp_peer_needs_update(struct sctp_association *asoc)
1397 {
1398         struct net *net = sock_net(asoc->base.sk);
1399         switch (asoc->state) {
1400         case SCTP_STATE_ESTABLISHED:
1401         case SCTP_STATE_SHUTDOWN_PENDING:
1402         case SCTP_STATE_SHUTDOWN_RECEIVED:
1403         case SCTP_STATE_SHUTDOWN_SENT:
1404                 if ((asoc->rwnd > asoc->a_rwnd) &&
1405                     ((asoc->rwnd - asoc->a_rwnd) >= max_t(__u32,
1406                            (asoc->base.sk->sk_rcvbuf >> net->sctp.rwnd_upd_shift),
1407                            asoc->pathmtu)))
1408                         return 1;
1409                 break;
1410         default:
1411                 break;
1412         }
1413         return 0;
1414 }
1415 
1416 /* Increase asoc's rwnd by len and send any window update SACK if needed. */
1417 void sctp_assoc_rwnd_increase(struct sctp_association *asoc, unsigned int len)
1418 {
1419         struct sctp_chunk *sack;
1420         struct timer_list *timer;
1421 
1422         if (asoc->rwnd_over) {
1423                 if (asoc->rwnd_over >= len) {
1424                         asoc->rwnd_over -= len;
1425                 } else {
1426                         asoc->rwnd += (len - asoc->rwnd_over);
1427                         asoc->rwnd_over = 0;
1428                 }
1429         } else {
1430                 asoc->rwnd += len;
1431         }
1432 
1433         /* If we had window pressure, start recovering it
1434          * once our rwnd had reached the accumulated pressure
1435          * threshold.  The idea is to recover slowly, but up
1436          * to the initial advertised window.
1437          */
1438         if (asoc->rwnd_press && asoc->rwnd >= asoc->rwnd_press) {
1439                 int change = min(asoc->pathmtu, asoc->rwnd_press);
1440                 asoc->rwnd += change;
1441                 asoc->rwnd_press -= change;
1442         }
1443 
1444         pr_debug("%s: asoc:%p rwnd increased by %d to (%u, %u) - %u\n",
1445                  __func__, asoc, len, asoc->rwnd, asoc->rwnd_over,
1446                  asoc->a_rwnd);
1447 
1448         /* Send a window update SACK if the rwnd has increased by at least the
1449          * minimum of the association's PMTU and half of the receive buffer.
1450          * The algorithm used is similar to the one described in
1451          * Section 4.2.3.3 of RFC 1122.
1452          */
1453         if (sctp_peer_needs_update(asoc)) {
1454                 asoc->a_rwnd = asoc->rwnd;
1455 
1456                 pr_debug("%s: sending window update SACK- asoc:%p rwnd:%u "
1457                          "a_rwnd:%u\n", __func__, asoc, asoc->rwnd,
1458                          asoc->a_rwnd);
1459 
1460                 sack = sctp_make_sack(asoc);
1461                 if (!sack)
1462                         return;
1463 
1464                 asoc->peer.sack_needed = 0;
1465 
1466                 sctp_outq_tail(&asoc->outqueue, sack);
1467 
1468                 /* Stop the SACK timer.  */
1469                 timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK];
1470                 if (del_timer(timer))
1471                         sctp_association_put(asoc);
1472         }
1473 }
1474 
1475 /* Decrease asoc's rwnd by len. */
1476 void sctp_assoc_rwnd_decrease(struct sctp_association *asoc, unsigned int len)
1477 {
1478         int rx_count;
1479         int over = 0;
1480 
1481         if (unlikely(!asoc->rwnd || asoc->rwnd_over))
1482                 pr_debug("%s: association:%p has asoc->rwnd:%u, "
1483                          "asoc->rwnd_over:%u!\n", __func__, asoc,
1484                          asoc->rwnd, asoc->rwnd_over);
1485 
1486         if (asoc->ep->rcvbuf_policy)
1487                 rx_count = atomic_read(&asoc->rmem_alloc);
1488         else
1489                 rx_count = atomic_read(&asoc->base.sk->sk_rmem_alloc);
1490 
1491         /* If we've reached or overflowed our receive buffer, announce
1492          * a 0 rwnd if rwnd would still be positive.  Store the
1493          * the pottential pressure overflow so that the window can be restored
1494          * back to original value.
1495          */
1496         if (rx_count >= asoc->base.sk->sk_rcvbuf)
1497                 over = 1;
1498 
1499         if (asoc->rwnd >= len) {
1500                 asoc->rwnd -= len;
1501                 if (over) {
1502                         asoc->rwnd_press += asoc->rwnd;
1503                         asoc->rwnd = 0;
1504                 }
1505         } else {
1506                 asoc->rwnd_over = len - asoc->rwnd;
1507                 asoc->rwnd = 0;
1508         }
1509 
1510         pr_debug("%s: asoc:%p rwnd decreased by %d to (%u, %u, %u)\n",
1511                  __func__, asoc, len, asoc->rwnd, asoc->rwnd_over,
1512                  asoc->rwnd_press);
1513 }
1514 
1515 /* Build the bind address list for the association based on info from the
1516  * local endpoint and the remote peer.
1517  */
1518 int sctp_assoc_set_bind_addr_from_ep(struct sctp_association *asoc,
1519                                      sctp_scope_t scope, gfp_t gfp)
1520 {
1521         int flags;
1522 
1523         /* Use scoping rules to determine the subset of addresses from
1524          * the endpoint.
1525          */
1526         flags = (PF_INET6 == asoc->base.sk->sk_family) ? SCTP_ADDR6_ALLOWED : 0;
1527         if (asoc->peer.ipv4_address)
1528                 flags |= SCTP_ADDR4_PEERSUPP;
1529         if (asoc->peer.ipv6_address)
1530                 flags |= SCTP_ADDR6_PEERSUPP;
1531 
1532         return sctp_bind_addr_copy(sock_net(asoc->base.sk),
1533                                    &asoc->base.bind_addr,
1534                                    &asoc->ep->base.bind_addr,
1535                                    scope, gfp, flags);
1536 }
1537 
1538 /* Build the association's bind address list from the cookie.  */
1539 int sctp_assoc_set_bind_addr_from_cookie(struct sctp_association *asoc,
1540                                          struct sctp_cookie *cookie,
1541                                          gfp_t gfp)
1542 {
1543         int var_size2 = ntohs(cookie->peer_init->chunk_hdr.length);
1544         int var_size3 = cookie->raw_addr_list_len;
1545         __u8 *raw = (__u8 *)cookie->peer_init + var_size2;
1546 
1547         return sctp_raw_to_bind_addrs(&asoc->base.bind_addr, raw, var_size3,
1548                                       asoc->ep->base.bind_addr.port, gfp);
1549 }
1550 
1551 /* Lookup laddr in the bind address list of an association. */
1552 int sctp_assoc_lookup_laddr(struct sctp_association *asoc,
1553                             const union sctp_addr *laddr)
1554 {
1555         int found = 0;
1556 
1557         if ((asoc->base.bind_addr.port == ntohs(laddr->v4.sin_port)) &&
1558             sctp_bind_addr_match(&asoc->base.bind_addr, laddr,
1559                                  sctp_sk(asoc->base.sk)))
1560                 found = 1;
1561 
1562         return found;
1563 }
1564 
1565 /* Set an association id for a given association */
1566 int sctp_assoc_set_id(struct sctp_association *asoc, gfp_t gfp)
1567 {
1568         bool preload = gfp & __GFP_WAIT;
1569         int ret;
1570 
1571         /* If the id is already assigned, keep it. */
1572         if (asoc->assoc_id)
1573                 return 0;
1574 
1575         if (preload)
1576                 idr_preload(gfp);
1577         spin_lock_bh(&sctp_assocs_id_lock);
1578         /* 0 is not a valid assoc_id, must be >= 1 */
1579         ret = idr_alloc_cyclic(&sctp_assocs_id, asoc, 1, 0, GFP_NOWAIT);
1580         spin_unlock_bh(&sctp_assocs_id_lock);
1581         if (preload)
1582                 idr_preload_end();
1583         if (ret < 0)
1584                 return ret;
1585 
1586         asoc->assoc_id = (sctp_assoc_t)ret;
1587         return 0;
1588 }
1589 
1590 /* Free the ASCONF queue */
1591 static void sctp_assoc_free_asconf_queue(struct sctp_association *asoc)
1592 {
1593         struct sctp_chunk *asconf;
1594         struct sctp_chunk *tmp;
1595 
1596         list_for_each_entry_safe(asconf, tmp, &asoc->addip_chunk_list, list) {
1597                 list_del_init(&asconf->list);
1598                 sctp_chunk_free(asconf);
1599         }
1600 }
1601 
1602 /* Free asconf_ack cache */
1603 static void sctp_assoc_free_asconf_acks(struct sctp_association *asoc)
1604 {
1605         struct sctp_chunk *ack;
1606         struct sctp_chunk *tmp;
1607 
1608         list_for_each_entry_safe(ack, tmp, &asoc->asconf_ack_list,
1609                                 transmitted_list) {
1610                 list_del_init(&ack->transmitted_list);
1611                 sctp_chunk_free(ack);
1612         }
1613 }
1614 
1615 /* Clean up the ASCONF_ACK queue */
1616 void sctp_assoc_clean_asconf_ack_cache(const struct sctp_association *asoc)
1617 {
1618         struct sctp_chunk *ack;
1619         struct sctp_chunk *tmp;
1620 
1621         /* We can remove all the entries from the queue up to
1622          * the "Peer-Sequence-Number".
1623          */
1624         list_for_each_entry_safe(ack, tmp, &asoc->asconf_ack_list,
1625                                 transmitted_list) {
1626                 if (ack->subh.addip_hdr->serial ==
1627                                 htonl(asoc->peer.addip_serial))
1628                         break;
1629 
1630                 list_del_init(&ack->transmitted_list);
1631                 sctp_chunk_free(ack);
1632         }
1633 }
1634 
1635 /* Find the ASCONF_ACK whose serial number matches ASCONF */
1636 struct sctp_chunk *sctp_assoc_lookup_asconf_ack(
1637                                         const struct sctp_association *asoc,
1638                                         __be32 serial)
1639 {
1640         struct sctp_chunk *ack;
1641 
1642         /* Walk through the list of cached ASCONF-ACKs and find the
1643          * ack chunk whose serial number matches that of the request.
1644          */
1645         list_for_each_entry(ack, &asoc->asconf_ack_list, transmitted_list) {
1646                 if (ack->subh.addip_hdr->serial == serial) {
1647                         sctp_chunk_hold(ack);
1648                         return ack;
1649                 }
1650         }
1651 
1652         return NULL;
1653 }
1654 
1655 void sctp_asconf_queue_teardown(struct sctp_association *asoc)
1656 {
1657         /* Free any cached ASCONF_ACK chunk. */
1658         sctp_assoc_free_asconf_acks(asoc);
1659 
1660         /* Free the ASCONF queue. */
1661         sctp_assoc_free_asconf_queue(asoc);
1662 
1663         /* Free any cached ASCONF chunk. */
1664         if (asoc->addip_last_asconf)
1665                 sctp_chunk_free(asoc->addip_last_asconf);
1666 }
1667 

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