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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, see
 26  * <http://www.gnu.org/licenses/>.
 27  *
 28  * Please send any bug reports or fixes you make to the
 29  * email address(es):
 30  *    lksctp developers <linux-sctp@vger.kernel.org>
 31  *
 32  * Written or modified by:
 33  *    La Monte H.P. Yarroll <piggy@acm.org>
 34  *    Karl Knutson          <karl@athena.chicago.il.us>
 35  *    Jon Grimm             <jgrimm@us.ibm.com>
 36  *    Xingang Guo           <xingang.guo@intel.com>
 37  *    Hui Huang             <hui.huang@nokia.com>
 38  *    Sridhar Samudrala     <sri@us.ibm.com>
 39  *    Daisy Chang           <daisyc@us.ibm.com>
 40  *    Ryan Layer            <rmlayer@us.ibm.com>
 41  *    Kevin Gao             <kevin.gao@intel.com>
 42  */
 43 
 44 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 45 
 46 #include <linux/types.h>
 47 #include <linux/fcntl.h>
 48 #include <linux/poll.h>
 49 #include <linux/init.h>
 50 
 51 #include <linux/slab.h>
 52 #include <linux/in.h>
 53 #include <net/ipv6.h>
 54 #include <net/sctp/sctp.h>
 55 #include <net/sctp/sm.h>
 56 
 57 /* Forward declarations for internal functions. */
 58 static void sctp_select_active_and_retran_path(struct sctp_association *asoc);
 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 
 94         /* Initialize the bind addr area.  */
 95         sctp_bind_addr_init(&asoc->base.bind_addr, ep->base.bind_addr.port);
 96 
 97         asoc->state = SCTP_STATE_CLOSED;
 98         asoc->cookie_life = ms_to_ktime(sp->assocparams.sasoc_cookie_life);
 99         asoc->user_frag = sp->user_frag;
100 
101         /* Set the association max_retrans and RTO values from the
102          * socket values.
103          */
104         asoc->max_retrans = sp->assocparams.sasoc_asocmaxrxt;
105         asoc->pf_retrans  = net->sctp.pf_retrans;
106 
107         asoc->rto_initial = msecs_to_jiffies(sp->rtoinfo.srto_initial);
108         asoc->rto_max = msecs_to_jiffies(sp->rtoinfo.srto_max);
109         asoc->rto_min = msecs_to_jiffies(sp->rtoinfo.srto_min);
110 
111         /* Initialize the association's heartbeat interval based on the
112          * sock configured value.
113          */
114         asoc->hbinterval = msecs_to_jiffies(sp->hbinterval);
115 
116         /* Initialize path max retrans value. */
117         asoc->pathmaxrxt = sp->pathmaxrxt;
118 
119         /* Initialize default path MTU. */
120         asoc->pathmtu = sp->pathmtu;
121 
122         /* Set association default SACK delay */
123         asoc->sackdelay = msecs_to_jiffies(sp->sackdelay);
124         asoc->sackfreq = sp->sackfreq;
125 
126         /* Set the association default flags controlling
127          * Heartbeat, SACK delay, and Path MTU Discovery.
128          */
129         asoc->param_flags = sp->param_flags;
130 
131         /* Initialize the maximum number of new data packets that can be sent
132          * in a burst.
133          */
134         asoc->max_burst = sp->max_burst;
135 
136         /* initialize association timers */
137         asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_COOKIE] = asoc->rto_initial;
138         asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_INIT] = asoc->rto_initial;
139         asoc->timeouts[SCTP_EVENT_TIMEOUT_T2_SHUTDOWN] = asoc->rto_initial;
140 
141         /* sctpimpguide Section 2.12.2
142          * If the 'T5-shutdown-guard' timer is used, it SHOULD be set to the
143          * recommended value of 5 times 'RTO.Max'.
144          */
145         asoc->timeouts[SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]
146                 = 5 * asoc->rto_max;
147 
148         asoc->timeouts[SCTP_EVENT_TIMEOUT_SACK] = asoc->sackdelay;
149         asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE] = sp->autoclose * HZ;
150 
151         /* Initializes the timers */
152         for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i)
153                 setup_timer(&asoc->timers[i], sctp_timer_events[i],
154                                 (unsigned long)asoc);
155 
156         /* Pull default initialization values from the sock options.
157          * Note: This assumes that the values have already been
158          * validated in the sock.
159          */
160         asoc->c.sinit_max_instreams = sp->initmsg.sinit_max_instreams;
161         asoc->c.sinit_num_ostreams  = sp->initmsg.sinit_num_ostreams;
162         asoc->max_init_attempts = sp->initmsg.sinit_max_attempts;
163 
164         asoc->max_init_timeo =
165                  msecs_to_jiffies(sp->initmsg.sinit_max_init_timeo);
166 
167         /* Set the local window size for receive.
168          * This is also the rcvbuf space per association.
169          * RFC 6 - A SCTP receiver MUST be able to receive a minimum of
170          * 1500 bytes in one SCTP packet.
171          */
172         if ((sk->sk_rcvbuf/2) < SCTP_DEFAULT_MINWINDOW)
173                 asoc->rwnd = SCTP_DEFAULT_MINWINDOW;
174         else
175                 asoc->rwnd = sk->sk_rcvbuf/2;
176 
177         asoc->a_rwnd = asoc->rwnd;
178 
179         /* Use my own max window until I learn something better.  */
180         asoc->peer.rwnd = SCTP_DEFAULT_MAXWINDOW;
181 
182         /* Initialize the receive memory counter */
183         atomic_set(&asoc->rmem_alloc, 0);
184 
185         init_waitqueue_head(&asoc->wait);
186 
187         asoc->c.my_vtag = sctp_generate_tag(ep);
188         asoc->c.my_port = ep->base.bind_addr.port;
189 
190         asoc->c.initial_tsn = sctp_generate_tsn(ep);
191 
192         asoc->next_tsn = asoc->c.initial_tsn;
193 
194         asoc->ctsn_ack_point = asoc->next_tsn - 1;
195         asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
196         asoc->highest_sacked = asoc->ctsn_ack_point;
197         asoc->last_cwr_tsn = asoc->ctsn_ack_point;
198 
199         /* ADDIP Section 4.1 Asconf Chunk Procedures
200          *
201          * When an endpoint has an ASCONF signaled change to be sent to the
202          * remote endpoint it should do the following:
203          * ...
204          * A2) a serial number should be assigned to the chunk. The serial
205          * number SHOULD be a monotonically increasing number. The serial
206          * numbers SHOULD be initialized at the start of the
207          * association to the same value as the initial TSN.
208          */
209         asoc->addip_serial = asoc->c.initial_tsn;
210 
211         INIT_LIST_HEAD(&asoc->addip_chunk_list);
212         INIT_LIST_HEAD(&asoc->asconf_ack_list);
213 
214         /* Make an empty list of remote transport addresses.  */
215         INIT_LIST_HEAD(&asoc->peer.transport_addr_list);
216 
217         /* RFC 2960 5.1 Normal Establishment of an Association
218          *
219          * After the reception of the first data chunk in an
220          * association the endpoint must immediately respond with a
221          * sack to acknowledge the data chunk.  Subsequent
222          * acknowledgements should be done as described in Section
223          * 6.2.
224          *
225          * [We implement this by telling a new association that it
226          * already received one packet.]
227          */
228         asoc->peer.sack_needed = 1;
229         asoc->peer.sack_generation = 1;
230 
231         /* Assume that the peer will tell us if he recognizes ASCONF
232          * as part of INIT exchange.
233          * The sctp_addip_noauth option is there for backward compatibility
234          * and will revert old behavior.
235          */
236         if (net->sctp.addip_noauth)
237                 asoc->peer.asconf_capable = 1;
238 
239         /* Create an input queue.  */
240         sctp_inq_init(&asoc->base.inqueue);
241         sctp_inq_set_th_handler(&asoc->base.inqueue, sctp_assoc_bh_rcv);
242 
243         /* Create an output queue.  */
244         sctp_outq_init(asoc, &asoc->outqueue);
245 
246         if (!sctp_ulpq_init(&asoc->ulpq, asoc))
247                 goto fail_init;
248 
249         /* Assume that peer would support both address types unless we are
250          * told otherwise.
251          */
252         asoc->peer.ipv4_address = 1;
253         if (asoc->base.sk->sk_family == PF_INET6)
254                 asoc->peer.ipv6_address = 1;
255         INIT_LIST_HEAD(&asoc->asocs);
256 
257         asoc->default_stream = sp->default_stream;
258         asoc->default_ppid = sp->default_ppid;
259         asoc->default_flags = sp->default_flags;
260         asoc->default_context = sp->default_context;
261         asoc->default_timetolive = sp->default_timetolive;
262         asoc->default_rcv_context = sp->default_rcv_context;
263 
264         /* AUTH related initializations */
265         INIT_LIST_HEAD(&asoc->endpoint_shared_keys);
266         err = sctp_auth_asoc_copy_shkeys(ep, asoc, gfp);
267         if (err)
268                 goto fail_init;
269 
270         asoc->active_key_id = ep->active_key_id;
271 
272         /* Save the hmacs and chunks list into this association */
273         if (ep->auth_hmacs_list)
274                 memcpy(asoc->c.auth_hmacs, ep->auth_hmacs_list,
275                         ntohs(ep->auth_hmacs_list->param_hdr.length));
276         if (ep->auth_chunk_list)
277                 memcpy(asoc->c.auth_chunks, ep->auth_chunk_list,
278                         ntohs(ep->auth_chunk_list->param_hdr.length));
279 
280         /* Get the AUTH random number for this association */
281         p = (sctp_paramhdr_t *)asoc->c.auth_random;
282         p->type = SCTP_PARAM_RANDOM;
283         p->length = htons(sizeof(sctp_paramhdr_t) + SCTP_AUTH_RANDOM_LENGTH);
284         get_random_bytes(p+1, SCTP_AUTH_RANDOM_LENGTH);
285 
286         return asoc;
287 
288 fail_init:
289         sock_put(asoc->base.sk);
290         sctp_endpoint_put(asoc->ep);
291         return NULL;
292 }
293 
294 /* Allocate and initialize a new association */
295 struct sctp_association *sctp_association_new(const struct sctp_endpoint *ep,
296                                          const struct sock *sk,
297                                          sctp_scope_t scope,
298                                          gfp_t gfp)
299 {
300         struct sctp_association *asoc;
301 
302         asoc = kzalloc(sizeof(*asoc), gfp);
303         if (!asoc)
304                 goto fail;
305 
306         if (!sctp_association_init(asoc, ep, sk, scope, gfp))
307                 goto fail_init;
308 
309         SCTP_DBG_OBJCNT_INC(assoc);
310 
311         pr_debug("Created asoc %p\n", asoc);
312 
313         return asoc;
314 
315 fail_init:
316         kfree(asoc);
317 fail:
318         return NULL;
319 }
320 
321 /* Free this association if possible.  There may still be users, so
322  * the actual deallocation may be delayed.
323  */
324 void sctp_association_free(struct sctp_association *asoc)
325 {
326         struct sock *sk = asoc->base.sk;
327         struct sctp_transport *transport;
328         struct list_head *pos, *temp;
329         int i;
330 
331         /* Only real associations count against the endpoint, so
332          * don't bother for if this is a temporary association.
333          */
334         if (!list_empty(&asoc->asocs)) {
335                 list_del(&asoc->asocs);
336 
337                 /* Decrement the backlog value for a TCP-style listening
338                  * socket.
339                  */
340                 if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
341                         sk->sk_ack_backlog--;
342         }
343 
344         /* Mark as dead, so other users can know this structure is
345          * going away.
346          */
347         asoc->base.dead = true;
348 
349         /* Dispose of any data lying around in the outqueue. */
350         sctp_outq_free(&asoc->outqueue);
351 
352         /* Dispose of any pending messages for the upper layer. */
353         sctp_ulpq_free(&asoc->ulpq);
354 
355         /* Dispose of any pending chunks on the inqueue. */
356         sctp_inq_free(&asoc->base.inqueue);
357 
358         sctp_tsnmap_free(&asoc->peer.tsn_map);
359 
360         /* Free ssnmap storage. */
361         sctp_ssnmap_free(asoc->ssnmap);
362 
363         /* Clean up the bound address list. */
364         sctp_bind_addr_free(&asoc->base.bind_addr);
365 
366         /* Do we need to go through all of our timers and
367          * delete them?   To be safe we will try to delete all, but we
368          * should be able to go through and make a guess based
369          * on our state.
370          */
371         for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i) {
372                 if (del_timer(&asoc->timers[i]))
373                         sctp_association_put(asoc);
374         }
375 
376         /* Free peer's cached cookie. */
377         kfree(asoc->peer.cookie);
378         kfree(asoc->peer.peer_random);
379         kfree(asoc->peer.peer_chunks);
380         kfree(asoc->peer.peer_hmacs);
381 
382         /* Release the transport structures. */
383         list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
384                 transport = list_entry(pos, struct sctp_transport, transports);
385                 list_del_rcu(pos);
386                 sctp_transport_free(transport);
387         }
388 
389         asoc->peer.transport_count = 0;
390 
391         sctp_asconf_queue_teardown(asoc);
392 
393         /* Free pending address space being deleted */
394         if (asoc->asconf_addr_del_pending != NULL)
395                 kfree(asoc->asconf_addr_del_pending);
396 
397         /* AUTH - Free the endpoint shared keys */
398         sctp_auth_destroy_keys(&asoc->endpoint_shared_keys);
399 
400         /* AUTH - Free the association shared key */
401         sctp_auth_key_put(asoc->asoc_shared_key);
402 
403         sctp_association_put(asoc);
404 }
405 
406 /* Cleanup and free up an association. */
407 static void sctp_association_destroy(struct sctp_association *asoc)
408 {
409         if (unlikely(!asoc->base.dead)) {
410                 WARN(1, "Attempt to destroy undead association %p!\n", asoc);
411                 return;
412         }
413 
414         sctp_endpoint_put(asoc->ep);
415         sock_put(asoc->base.sk);
416 
417         if (asoc->assoc_id != 0) {
418                 spin_lock_bh(&sctp_assocs_id_lock);
419                 idr_remove(&sctp_assocs_id, asoc->assoc_id);
420                 spin_unlock_bh(&sctp_assocs_id_lock);
421         }
422 
423         WARN_ON(atomic_read(&asoc->rmem_alloc));
424 
425         kfree(asoc);
426         SCTP_DBG_OBJCNT_DEC(assoc);
427 }
428 
429 /* Change the primary destination address for the peer. */
430 void sctp_assoc_set_primary(struct sctp_association *asoc,
431                             struct sctp_transport *transport)
432 {
433         int changeover = 0;
434 
435         /* it's a changeover only if we already have a primary path
436          * that we are changing
437          */
438         if (asoc->peer.primary_path != NULL &&
439             asoc->peer.primary_path != transport)
440                 changeover = 1 ;
441 
442         asoc->peer.primary_path = transport;
443 
444         /* Set a default msg_name for events. */
445         memcpy(&asoc->peer.primary_addr, &transport->ipaddr,
446                sizeof(union sctp_addr));
447 
448         /* If the primary path is changing, assume that the
449          * user wants to use this new path.
450          */
451         if ((transport->state == SCTP_ACTIVE) ||
452             (transport->state == SCTP_UNKNOWN))
453                 asoc->peer.active_path = transport;
454 
455         /*
456          * SFR-CACC algorithm:
457          * Upon the receipt of a request to change the primary
458          * destination address, on the data structure for the new
459          * primary destination, the sender MUST do the following:
460          *
461          * 1) If CHANGEOVER_ACTIVE is set, then there was a switch
462          * to this destination address earlier. The sender MUST set
463          * CYCLING_CHANGEOVER to indicate that this switch is a
464          * double switch to the same destination address.
465          *
466          * Really, only bother is we have data queued or outstanding on
467          * the association.
468          */
469         if (!asoc->outqueue.outstanding_bytes && !asoc->outqueue.out_qlen)
470                 return;
471 
472         if (transport->cacc.changeover_active)
473                 transport->cacc.cycling_changeover = changeover;
474 
475         /* 2) The sender MUST set CHANGEOVER_ACTIVE to indicate that
476          * a changeover has occurred.
477          */
478         transport->cacc.changeover_active = changeover;
479 
480         /* 3) The sender MUST store the next TSN to be sent in
481          * next_tsn_at_change.
482          */
483         transport->cacc.next_tsn_at_change = asoc->next_tsn;
484 }
485 
486 /* Remove a transport from an association.  */
487 void sctp_assoc_rm_peer(struct sctp_association *asoc,
488                         struct sctp_transport *peer)
489 {
490         struct list_head        *pos;
491         struct sctp_transport   *transport;
492 
493         pr_debug("%s: association:%p addr:%pISpc\n",
494                  __func__, asoc, &peer->ipaddr.sa);
495 
496         /* If we are to remove the current retran_path, update it
497          * to the next peer before removing this peer from the list.
498          */
499         if (asoc->peer.retran_path == peer)
500                 sctp_assoc_update_retran_path(asoc);
501 
502         /* Remove this peer from the list. */
503         list_del_rcu(&peer->transports);
504 
505         /* Get the first transport of asoc. */
506         pos = asoc->peer.transport_addr_list.next;
507         transport = list_entry(pos, struct sctp_transport, transports);
508 
509         /* Update any entries that match the peer to be deleted. */
510         if (asoc->peer.primary_path == peer)
511                 sctp_assoc_set_primary(asoc, transport);
512         if (asoc->peer.active_path == peer)
513                 asoc->peer.active_path = transport;
514         if (asoc->peer.retran_path == peer)
515                 asoc->peer.retran_path = transport;
516         if (asoc->peer.last_data_from == peer)
517                 asoc->peer.last_data_from = transport;
518 
519         /* If we remove the transport an INIT was last sent to, set it to
520          * NULL. Combined with the update of the retran path above, this
521          * will cause the next INIT to be sent to the next available
522          * transport, maintaining the cycle.
523          */
524         if (asoc->init_last_sent_to == peer)
525                 asoc->init_last_sent_to = NULL;
526 
527         /* If we remove the transport an SHUTDOWN was last sent to, set it
528          * to NULL. Combined with the update of the retran path above, this
529          * will cause the next SHUTDOWN to be sent to the next available
530          * transport, maintaining the cycle.
531          */
532         if (asoc->shutdown_last_sent_to == peer)
533                 asoc->shutdown_last_sent_to = NULL;
534 
535         /* If we remove the transport an ASCONF was last sent to, set it to
536          * NULL.
537          */
538         if (asoc->addip_last_asconf &&
539             asoc->addip_last_asconf->transport == peer)
540                 asoc->addip_last_asconf->transport = NULL;
541 
542         /* If we have something on the transmitted list, we have to
543          * save it off.  The best place is the active path.
544          */
545         if (!list_empty(&peer->transmitted)) {
546                 struct sctp_transport *active = asoc->peer.active_path;
547                 struct sctp_chunk *ch;
548 
549                 /* Reset the transport of each chunk on this list */
550                 list_for_each_entry(ch, &peer->transmitted,
551                                         transmitted_list) {
552                         ch->transport = NULL;
553                         ch->rtt_in_progress = 0;
554                 }
555 
556                 list_splice_tail_init(&peer->transmitted,
557                                         &active->transmitted);
558 
559                 /* Start a T3 timer here in case it wasn't running so
560                  * that these migrated packets have a chance to get
561                  * retransmitted.
562                  */
563                 if (!timer_pending(&active->T3_rtx_timer))
564                         if (!mod_timer(&active->T3_rtx_timer,
565                                         jiffies + active->rto))
566                                 sctp_transport_hold(active);
567         }
568 
569         asoc->peer.transport_count--;
570 
571         sctp_transport_free(peer);
572 }
573 
574 /* Add a transport address to an association.  */
575 struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc,
576                                            const union sctp_addr *addr,
577                                            const gfp_t gfp,
578                                            const int peer_state)
579 {
580         struct net *net = sock_net(asoc->base.sk);
581         struct sctp_transport *peer;
582         struct sctp_sock *sp;
583         unsigned short port;
584 
585         sp = sctp_sk(asoc->base.sk);
586 
587         /* AF_INET and AF_INET6 share common port field. */
588         port = ntohs(addr->v4.sin_port);
589 
590         pr_debug("%s: association:%p addr:%pISpc state:%d\n", __func__,
591                  asoc, &addr->sa, peer_state);
592 
593         /* Set the port if it has not been set yet.  */
594         if (0 == asoc->peer.port)
595                 asoc->peer.port = port;
596 
597         /* Check to see if this is a duplicate. */
598         peer = sctp_assoc_lookup_paddr(asoc, addr);
599         if (peer) {
600                 /* An UNKNOWN state is only set on transports added by
601                  * user in sctp_connectx() call.  Such transports should be
602                  * considered CONFIRMED per RFC 4960, Section 5.4.
603                  */
604                 if (peer->state == SCTP_UNKNOWN) {
605                         peer->state = SCTP_ACTIVE;
606                 }
607                 return peer;
608         }
609 
610         peer = sctp_transport_new(net, addr, gfp);
611         if (!peer)
612                 return NULL;
613 
614         sctp_transport_set_owner(peer, asoc);
615 
616         /* Initialize the peer's heartbeat interval based on the
617          * association configured value.
618          */
619         peer->hbinterval = asoc->hbinterval;
620 
621         /* Set the path max_retrans.  */
622         peer->pathmaxrxt = asoc->pathmaxrxt;
623 
624         /* And the partial failure retrans threshold */
625         peer->pf_retrans = asoc->pf_retrans;
626 
627         /* Initialize the peer's SACK delay timeout based on the
628          * association configured value.
629          */
630         peer->sackdelay = asoc->sackdelay;
631         peer->sackfreq = asoc->sackfreq;
632 
633         /* Enable/disable heartbeat, SACK delay, and path MTU discovery
634          * based on association setting.
635          */
636         peer->param_flags = asoc->param_flags;
637 
638         sctp_transport_route(peer, NULL, sp);
639 
640         /* Initialize the pmtu of the transport. */
641         if (peer->param_flags & SPP_PMTUD_DISABLE) {
642                 if (asoc->pathmtu)
643                         peer->pathmtu = asoc->pathmtu;
644                 else
645                         peer->pathmtu = SCTP_DEFAULT_MAXSEGMENT;
646         }
647 
648         /* If this is the first transport addr on this association,
649          * initialize the association PMTU to the peer's PMTU.
650          * If not and the current association PMTU is higher than the new
651          * peer's PMTU, reset the association PMTU to the new peer's PMTU.
652          */
653         if (asoc->pathmtu)
654                 asoc->pathmtu = min_t(int, peer->pathmtu, asoc->pathmtu);
655         else
656                 asoc->pathmtu = peer->pathmtu;
657 
658         pr_debug("%s: association:%p PMTU set to %d\n", __func__, asoc,
659                  asoc->pathmtu);
660 
661         peer->pmtu_pending = 0;
662 
663         asoc->frag_point = sctp_frag_point(asoc, asoc->pathmtu);
664 
665         /* The asoc->peer.port might not be meaningful yet, but
666          * initialize the packet structure anyway.
667          */
668         sctp_packet_init(&peer->packet, peer, asoc->base.bind_addr.port,
669                          asoc->peer.port);
670 
671         /* 7.2.1 Slow-Start
672          *
673          * o The initial cwnd before DATA transmission or after a sufficiently
674          *   long idle period MUST be set to
675          *      min(4*MTU, max(2*MTU, 4380 bytes))
676          *
677          * o The initial value of ssthresh MAY be arbitrarily high
678          *   (for example, implementations MAY use the size of the
679          *   receiver advertised window).
680          */
681         peer->cwnd = min(4*asoc->pathmtu, max_t(__u32, 2*asoc->pathmtu, 4380));
682 
683         /* At this point, we may not have the receiver's advertised window,
684          * so initialize ssthresh to the default value and it will be set
685          * later when we process the INIT.
686          */
687         peer->ssthresh = SCTP_DEFAULT_MAXWINDOW;
688 
689         peer->partial_bytes_acked = 0;
690         peer->flight_size = 0;
691         peer->burst_limited = 0;
692 
693         /* Set the transport's RTO.initial value */
694         peer->rto = asoc->rto_initial;
695         sctp_max_rto(asoc, peer);
696 
697         /* Set the peer's active state. */
698         peer->state = peer_state;
699 
700         /* Attach the remote transport to our asoc.  */
701         list_add_tail_rcu(&peer->transports, &asoc->peer.transport_addr_list);
702         asoc->peer.transport_count++;
703 
704         /* If we do not yet have a primary path, set one.  */
705         if (!asoc->peer.primary_path) {
706                 sctp_assoc_set_primary(asoc, peer);
707                 asoc->peer.retran_path = peer;
708         }
709 
710         if (asoc->peer.active_path == asoc->peer.retran_path &&
711             peer->state != SCTP_UNCONFIRMED) {
712                 asoc->peer.retran_path = peer;
713         }
714 
715         return peer;
716 }
717 
718 /* Delete a transport address from an association.  */
719 void sctp_assoc_del_peer(struct sctp_association *asoc,
720                          const union sctp_addr *addr)
721 {
722         struct list_head        *pos;
723         struct list_head        *temp;
724         struct sctp_transport   *transport;
725 
726         list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
727                 transport = list_entry(pos, struct sctp_transport, transports);
728                 if (sctp_cmp_addr_exact(addr, &transport->ipaddr)) {
729                         /* Do book keeping for removing the peer and free it. */
730                         sctp_assoc_rm_peer(asoc, transport);
731                         break;
732                 }
733         }
734 }
735 
736 /* Lookup a transport by address. */
737 struct sctp_transport *sctp_assoc_lookup_paddr(
738                                         const struct sctp_association *asoc,
739                                         const union sctp_addr *address)
740 {
741         struct sctp_transport *t;
742 
743         /* Cycle through all transports searching for a peer address. */
744 
745         list_for_each_entry(t, &asoc->peer.transport_addr_list,
746                         transports) {
747                 if (sctp_cmp_addr_exact(address, &t->ipaddr))
748                         return t;
749         }
750 
751         return NULL;
752 }
753 
754 /* Remove all transports except a give one */
755 void sctp_assoc_del_nonprimary_peers(struct sctp_association *asoc,
756                                      struct sctp_transport *primary)
757 {
758         struct sctp_transport   *temp;
759         struct sctp_transport   *t;
760 
761         list_for_each_entry_safe(t, temp, &asoc->peer.transport_addr_list,
762                                  transports) {
763                 /* if the current transport is not the primary one, delete it */
764                 if (t != primary)
765                         sctp_assoc_rm_peer(asoc, t);
766         }
767 }
768 
769 /* Engage in transport control operations.
770  * Mark the transport up or down and send a notification to the user.
771  * Select and update the new active and retran paths.
772  */
773 void sctp_assoc_control_transport(struct sctp_association *asoc,
774                                   struct sctp_transport *transport,
775                                   sctp_transport_cmd_t command,
776                                   sctp_sn_error_t error)
777 {
778         struct sctp_ulpevent *event;
779         struct sockaddr_storage addr;
780         int spc_state = 0;
781         bool ulp_notify = true;
782 
783         /* Record the transition on the transport.  */
784         switch (command) {
785         case SCTP_TRANSPORT_UP:
786                 /* If we are moving from UNCONFIRMED state due
787                  * to heartbeat success, report the SCTP_ADDR_CONFIRMED
788                  * state to the user, otherwise report SCTP_ADDR_AVAILABLE.
789                  */
790                 if (SCTP_UNCONFIRMED == transport->state &&
791                     SCTP_HEARTBEAT_SUCCESS == error)
792                         spc_state = SCTP_ADDR_CONFIRMED;
793                 else
794                         spc_state = SCTP_ADDR_AVAILABLE;
795                 /* Don't inform ULP about transition from PF to
796                  * active state and set cwnd to 1 MTU, see SCTP
797                  * Quick failover draft section 5.1, point 5
798                  */
799                 if (transport->state == SCTP_PF) {
800                         ulp_notify = false;
801                         transport->cwnd = asoc->pathmtu;
802                 }
803                 transport->state = SCTP_ACTIVE;
804                 break;
805 
806         case SCTP_TRANSPORT_DOWN:
807                 /* If the transport was never confirmed, do not transition it
808                  * to inactive state.  Also, release the cached route since
809                  * there may be a better route next time.
810                  */
811                 if (transport->state != SCTP_UNCONFIRMED)
812                         transport->state = SCTP_INACTIVE;
813                 else {
814                         dst_release(transport->dst);
815                         transport->dst = NULL;
816                         ulp_notify = false;
817                 }
818 
819                 spc_state = SCTP_ADDR_UNREACHABLE;
820                 break;
821 
822         case SCTP_TRANSPORT_PF:
823                 transport->state = SCTP_PF;
824                 ulp_notify = false;
825                 break;
826 
827         default:
828                 return;
829         }
830 
831         /* Generate and send a SCTP_PEER_ADDR_CHANGE notification
832          * to the user.
833          */
834         if (ulp_notify) {
835                 memset(&addr, 0, sizeof(struct sockaddr_storage));
836                 memcpy(&addr, &transport->ipaddr,
837                        transport->af_specific->sockaddr_len);
838 
839                 event = sctp_ulpevent_make_peer_addr_change(asoc, &addr,
840                                         0, spc_state, error, GFP_ATOMIC);
841                 if (event)
842                         sctp_ulpq_tail_event(&asoc->ulpq, event);
843         }
844 
845         /* Select new active and retran paths. */
846         sctp_select_active_and_retran_path(asoc);
847 }
848 
849 /* Hold a reference to an association. */
850 void sctp_association_hold(struct sctp_association *asoc)
851 {
852         atomic_inc(&asoc->base.refcnt);
853 }
854 
855 /* Release a reference to an association and cleanup
856  * if there are no more references.
857  */
858 void sctp_association_put(struct sctp_association *asoc)
859 {
860         if (atomic_dec_and_test(&asoc->base.refcnt))
861                 sctp_association_destroy(asoc);
862 }
863 
864 /* Allocate the next TSN, Transmission Sequence Number, for the given
865  * association.
866  */
867 __u32 sctp_association_get_next_tsn(struct sctp_association *asoc)
868 {
869         /* From Section 1.6 Serial Number Arithmetic:
870          * Transmission Sequence Numbers wrap around when they reach
871          * 2**32 - 1.  That is, the next TSN a DATA chunk MUST use
872          * after transmitting TSN = 2*32 - 1 is TSN = 0.
873          */
874         __u32 retval = asoc->next_tsn;
875         asoc->next_tsn++;
876         asoc->unack_data++;
877 
878         return retval;
879 }
880 
881 /* Compare two addresses to see if they match.  Wildcard addresses
882  * only match themselves.
883  */
884 int sctp_cmp_addr_exact(const union sctp_addr *ss1,
885                         const union sctp_addr *ss2)
886 {
887         struct sctp_af *af;
888 
889         af = sctp_get_af_specific(ss1->sa.sa_family);
890         if (unlikely(!af))
891                 return 0;
892 
893         return af->cmp_addr(ss1, ss2);
894 }
895 
896 /* Return an ecne chunk to get prepended to a packet.
897  * Note:  We are sly and return a shared, prealloced chunk.  FIXME:
898  * No we don't, but we could/should.
899  */
900 struct sctp_chunk *sctp_get_ecne_prepend(struct sctp_association *asoc)
901 {
902         if (!asoc->need_ecne)
903                 return NULL;
904 
905         /* Send ECNE if needed.
906          * Not being able to allocate a chunk here is not deadly.
907          */
908         return sctp_make_ecne(asoc, asoc->last_ecne_tsn);
909 }
910 
911 /*
912  * Find which transport this TSN was sent on.
913  */
914 struct sctp_transport *sctp_assoc_lookup_tsn(struct sctp_association *asoc,
915                                              __u32 tsn)
916 {
917         struct sctp_transport *active;
918         struct sctp_transport *match;
919         struct sctp_transport *transport;
920         struct sctp_chunk *chunk;
921         __be32 key = htonl(tsn);
922 
923         match = NULL;
924 
925         /*
926          * FIXME: In general, find a more efficient data structure for
927          * searching.
928          */
929 
930         /*
931          * The general strategy is to search each transport's transmitted
932          * list.   Return which transport this TSN lives on.
933          *
934          * Let's be hopeful and check the active_path first.
935          * Another optimization would be to know if there is only one
936          * outbound path and not have to look for the TSN at all.
937          *
938          */
939 
940         active = asoc->peer.active_path;
941 
942         list_for_each_entry(chunk, &active->transmitted,
943                         transmitted_list) {
944 
945                 if (key == chunk->subh.data_hdr->tsn) {
946                         match = active;
947                         goto out;
948                 }
949         }
950 
951         /* If not found, go search all the other transports. */
952         list_for_each_entry(transport, &asoc->peer.transport_addr_list,
953                         transports) {
954 
955                 if (transport == active)
956                         continue;
957                 list_for_each_entry(chunk, &transport->transmitted,
958                                 transmitted_list) {
959                         if (key == chunk->subh.data_hdr->tsn) {
960                                 match = transport;
961                                 goto out;
962                         }
963                 }
964         }
965 out:
966         return match;
967 }
968 
969 /* Is this the association we are looking for? */
970 struct sctp_transport *sctp_assoc_is_match(struct sctp_association *asoc,
971                                            struct net *net,
972                                            const union sctp_addr *laddr,
973                                            const union sctp_addr *paddr)
974 {
975         struct sctp_transport *transport;
976 
977         if ((htons(asoc->base.bind_addr.port) == laddr->v4.sin_port) &&
978             (htons(asoc->peer.port) == paddr->v4.sin_port) &&
979             net_eq(sock_net(asoc->base.sk), net)) {
980                 transport = sctp_assoc_lookup_paddr(asoc, paddr);
981                 if (!transport)
982                         goto out;
983 
984                 if (sctp_bind_addr_match(&asoc->base.bind_addr, laddr,
985                                          sctp_sk(asoc->base.sk)))
986                         goto out;
987         }
988         transport = NULL;
989 
990 out:
991         return transport;
992 }
993 
994 /* Do delayed input processing.  This is scheduled by sctp_rcv(). */
995 static void sctp_assoc_bh_rcv(struct work_struct *work)
996 {
997         struct sctp_association *asoc =
998                 container_of(work, struct sctp_association,
999                              base.inqueue.immediate);
1000         struct net *net = sock_net(asoc->base.sk);
1001         struct sctp_endpoint *ep;
1002         struct sctp_chunk *chunk;
1003         struct sctp_inq *inqueue;
1004         int state;
1005         sctp_subtype_t subtype;
1006         int error = 0;
1007 
1008         /* The association should be held so we should be safe. */
1009         ep = asoc->ep;
1010 
1011         inqueue = &asoc->base.inqueue;
1012         sctp_association_hold(asoc);
1013         while (NULL != (chunk = sctp_inq_pop(inqueue))) {
1014                 state = asoc->state;
1015                 subtype = SCTP_ST_CHUNK(chunk->chunk_hdr->type);
1016 
1017                 /* SCTP-AUTH, Section 6.3:
1018                  *    The receiver has a list of chunk types which it expects
1019                  *    to be received only after an AUTH-chunk.  This list has
1020                  *    been sent to the peer during the association setup.  It
1021                  *    MUST silently discard these chunks if they are not placed
1022                  *    after an AUTH chunk in the packet.
1023                  */
1024                 if (sctp_auth_recv_cid(subtype.chunk, asoc) && !chunk->auth)
1025                         continue;
1026 
1027                 /* Remember where the last DATA chunk came from so we
1028                  * know where to send the SACK.
1029                  */
1030                 if (sctp_chunk_is_data(chunk))
1031                         asoc->peer.last_data_from = chunk->transport;
1032                 else {
1033                         SCTP_INC_STATS(net, SCTP_MIB_INCTRLCHUNKS);
1034                         asoc->stats.ictrlchunks++;
1035                         if (chunk->chunk_hdr->type == SCTP_CID_SACK)
1036                                 asoc->stats.isacks++;
1037                 }
1038 
1039                 if (chunk->transport)
1040                         chunk->transport->last_time_heard = ktime_get();
1041 
1042                 /* Run through the state machine. */
1043                 error = sctp_do_sm(net, SCTP_EVENT_T_CHUNK, subtype,
1044                                    state, ep, asoc, chunk, GFP_ATOMIC);
1045 
1046                 /* Check to see if the association is freed in response to
1047                  * the incoming chunk.  If so, get out of the while loop.
1048                  */
1049                 if (asoc->base.dead)
1050                         break;
1051 
1052                 /* If there is an error on chunk, discard this packet. */
1053                 if (error && chunk)
1054                         chunk->pdiscard = 1;
1055         }
1056         sctp_association_put(asoc);
1057 }
1058 
1059 /* This routine moves an association from its old sk to a new sk.  */
1060 void sctp_assoc_migrate(struct sctp_association *assoc, struct sock *newsk)
1061 {
1062         struct sctp_sock *newsp = sctp_sk(newsk);
1063         struct sock *oldsk = assoc->base.sk;
1064 
1065         /* Delete the association from the old endpoint's list of
1066          * associations.
1067          */
1068         list_del_init(&assoc->asocs);
1069 
1070         /* Decrement the backlog value for a TCP-style socket. */
1071         if (sctp_style(oldsk, TCP))
1072                 oldsk->sk_ack_backlog--;
1073 
1074         /* Release references to the old endpoint and the sock.  */
1075         sctp_endpoint_put(assoc->ep);
1076         sock_put(assoc->base.sk);
1077 
1078         /* Get a reference to the new endpoint.  */
1079         assoc->ep = newsp->ep;
1080         sctp_endpoint_hold(assoc->ep);
1081 
1082         /* Get a reference to the new sock.  */
1083         assoc->base.sk = newsk;
1084         sock_hold(assoc->base.sk);
1085 
1086         /* Add the association to the new endpoint's list of associations.  */
1087         sctp_endpoint_add_asoc(newsp->ep, assoc);
1088 }
1089 
1090 /* Update an association (possibly from unexpected COOKIE-ECHO processing).  */
1091 void sctp_assoc_update(struct sctp_association *asoc,
1092                        struct sctp_association *new)
1093 {
1094         struct sctp_transport *trans;
1095         struct list_head *pos, *temp;
1096 
1097         /* Copy in new parameters of peer. */
1098         asoc->c = new->c;
1099         asoc->peer.rwnd = new->peer.rwnd;
1100         asoc->peer.sack_needed = new->peer.sack_needed;
1101         asoc->peer.auth_capable = new->peer.auth_capable;
1102         asoc->peer.i = new->peer.i;
1103         sctp_tsnmap_init(&asoc->peer.tsn_map, SCTP_TSN_MAP_INITIAL,
1104                          asoc->peer.i.initial_tsn, GFP_ATOMIC);
1105 
1106         /* Remove any peer addresses not present in the new association. */
1107         list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
1108                 trans = list_entry(pos, struct sctp_transport, transports);
1109                 if (!sctp_assoc_lookup_paddr(new, &trans->ipaddr)) {
1110                         sctp_assoc_rm_peer(asoc, trans);
1111                         continue;
1112                 }
1113 
1114                 if (asoc->state >= SCTP_STATE_ESTABLISHED)
1115                         sctp_transport_reset(trans);
1116         }
1117 
1118         /* If the case is A (association restart), use
1119          * initial_tsn as next_tsn. If the case is B, use
1120          * current next_tsn in case data sent to peer
1121          * has been discarded and needs retransmission.
1122          */
1123         if (asoc->state >= SCTP_STATE_ESTABLISHED) {
1124                 asoc->next_tsn = new->next_tsn;
1125                 asoc->ctsn_ack_point = new->ctsn_ack_point;
1126                 asoc->adv_peer_ack_point = new->adv_peer_ack_point;
1127 
1128                 /* Reinitialize SSN for both local streams
1129                  * and peer's streams.
1130                  */
1131                 sctp_ssnmap_clear(asoc->ssnmap);
1132 
1133                 /* Flush the ULP reassembly and ordered queue.
1134                  * Any data there will now be stale and will
1135                  * cause problems.
1136                  */
1137                 sctp_ulpq_flush(&asoc->ulpq);
1138 
1139                 /* reset the overall association error count so
1140                  * that the restarted association doesn't get torn
1141                  * down on the next retransmission timer.
1142                  */
1143                 asoc->overall_error_count = 0;
1144 
1145         } else {
1146                 /* Add any peer addresses from the new association. */
1147                 list_for_each_entry(trans, &new->peer.transport_addr_list,
1148                                 transports) {
1149                         if (!sctp_assoc_lookup_paddr(asoc, &trans->ipaddr))
1150                                 sctp_assoc_add_peer(asoc, &trans->ipaddr,
1151                                                     GFP_ATOMIC, trans->state);
1152                 }
1153 
1154                 asoc->ctsn_ack_point = asoc->next_tsn - 1;
1155                 asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
1156                 if (!asoc->ssnmap) {
1157                         /* Move the ssnmap. */
1158                         asoc->ssnmap = new->ssnmap;
1159                         new->ssnmap = NULL;
1160                 }
1161 
1162                 if (!asoc->assoc_id) {
1163                         /* get a new association id since we don't have one
1164                          * yet.
1165                          */
1166                         sctp_assoc_set_id(asoc, GFP_ATOMIC);
1167                 }
1168         }
1169 
1170         /* SCTP-AUTH: Save the peer parameters from the new associations
1171          * and also move the association shared keys over
1172          */
1173         kfree(asoc->peer.peer_random);
1174         asoc->peer.peer_random = new->peer.peer_random;
1175         new->peer.peer_random = NULL;
1176 
1177         kfree(asoc->peer.peer_chunks);
1178         asoc->peer.peer_chunks = new->peer.peer_chunks;
1179         new->peer.peer_chunks = NULL;
1180 
1181         kfree(asoc->peer.peer_hmacs);
1182         asoc->peer.peer_hmacs = new->peer.peer_hmacs;
1183         new->peer.peer_hmacs = NULL;
1184 
1185         sctp_auth_key_put(asoc->asoc_shared_key);
1186         sctp_auth_asoc_init_active_key(asoc, GFP_ATOMIC);
1187 }
1188 
1189 /* Update the retran path for sending a retransmitted packet.
1190  * See also RFC4960, 6.4. Multi-Homed SCTP Endpoints:
1191  *
1192  *   When there is outbound data to send and the primary path
1193  *   becomes inactive (e.g., due to failures), or where the
1194  *   SCTP user explicitly requests to send data to an
1195  *   inactive destination transport address, before reporting
1196  *   an error to its ULP, the SCTP endpoint should try to send
1197  *   the data to an alternate active destination transport
1198  *   address if one exists.
1199  *
1200  *   When retransmitting data that timed out, if the endpoint
1201  *   is multihomed, it should consider each source-destination
1202  *   address pair in its retransmission selection policy.
1203  *   When retransmitting timed-out data, the endpoint should
1204  *   attempt to pick the most divergent source-destination
1205  *   pair from the original source-destination pair to which
1206  *   the packet was transmitted.
1207  *
1208  *   Note: Rules for picking the most divergent source-destination
1209  *   pair are an implementation decision and are not specified
1210  *   within this document.
1211  *
1212  * Our basic strategy is to round-robin transports in priorities
1213  * according to sctp_state_prio_map[] e.g., if no such
1214  * transport with state SCTP_ACTIVE exists, round-robin through
1215  * SCTP_UNKNOWN, etc. You get the picture.
1216  */
1217 static const u8 sctp_trans_state_to_prio_map[] = {
1218         [SCTP_ACTIVE]   = 3,    /* best case */
1219         [SCTP_UNKNOWN]  = 2,
1220         [SCTP_PF]       = 1,
1221         [SCTP_INACTIVE] = 0,    /* worst case */
1222 };
1223 
1224 static u8 sctp_trans_score(const struct sctp_transport *trans)
1225 {
1226         return sctp_trans_state_to_prio_map[trans->state];
1227 }
1228 
1229 static struct sctp_transport *sctp_trans_elect_tie(struct sctp_transport *trans1,
1230                                                    struct sctp_transport *trans2)
1231 {
1232         if (trans1->error_count > trans2->error_count) {
1233                 return trans2;
1234         } else if (trans1->error_count == trans2->error_count &&
1235                    ktime_after(trans2->last_time_heard,
1236                                trans1->last_time_heard)) {
1237                 return trans2;
1238         } else {
1239                 return trans1;
1240         }
1241 }
1242 
1243 static struct sctp_transport *sctp_trans_elect_best(struct sctp_transport *curr,
1244                                                     struct sctp_transport *best)
1245 {
1246         u8 score_curr, score_best;
1247 
1248         if (best == NULL || curr == best)
1249                 return curr;
1250 
1251         score_curr = sctp_trans_score(curr);
1252         score_best = sctp_trans_score(best);
1253 
1254         /* First, try a score-based selection if both transport states
1255          * differ. If we're in a tie, lets try to make a more clever
1256          * decision here based on error counts and last time heard.
1257          */
1258         if (score_curr > score_best)
1259                 return curr;
1260         else if (score_curr == score_best)
1261                 return sctp_trans_elect_tie(curr, best);
1262         else
1263                 return best;
1264 }
1265 
1266 void sctp_assoc_update_retran_path(struct sctp_association *asoc)
1267 {
1268         struct sctp_transport *trans = asoc->peer.retran_path;
1269         struct sctp_transport *trans_next = NULL;
1270 
1271         /* We're done as we only have the one and only path. */
1272         if (asoc->peer.transport_count == 1)
1273                 return;
1274         /* If active_path and retran_path are the same and active,
1275          * then this is the only active path. Use it.
1276          */
1277         if (asoc->peer.active_path == asoc->peer.retran_path &&
1278             asoc->peer.active_path->state == SCTP_ACTIVE)
1279                 return;
1280 
1281         /* Iterate from retran_path's successor back to retran_path. */
1282         for (trans = list_next_entry(trans, transports); 1;
1283              trans = list_next_entry(trans, transports)) {
1284                 /* Manually skip the head element. */
1285                 if (&trans->transports == &asoc->peer.transport_addr_list)
1286                         continue;
1287                 if (trans->state == SCTP_UNCONFIRMED)
1288                         continue;
1289                 trans_next = sctp_trans_elect_best(trans, trans_next);
1290                 /* Active is good enough for immediate return. */
1291                 if (trans_next->state == SCTP_ACTIVE)
1292                         break;
1293                 /* We've reached the end, time to update path. */
1294                 if (trans == asoc->peer.retran_path)
1295                         break;
1296         }
1297 
1298         asoc->peer.retran_path = trans_next;
1299 
1300         pr_debug("%s: association:%p updated new path to addr:%pISpc\n",
1301                  __func__, asoc, &asoc->peer.retran_path->ipaddr.sa);
1302 }
1303 
1304 static void sctp_select_active_and_retran_path(struct sctp_association *asoc)
1305 {
1306         struct sctp_transport *trans, *trans_pri = NULL, *trans_sec = NULL;
1307         struct sctp_transport *trans_pf = NULL;
1308 
1309         /* Look for the two most recently used active transports. */
1310         list_for_each_entry(trans, &asoc->peer.transport_addr_list,
1311                             transports) {
1312                 /* Skip uninteresting transports. */
1313                 if (trans->state == SCTP_INACTIVE ||
1314                     trans->state == SCTP_UNCONFIRMED)
1315                         continue;
1316                 /* Keep track of the best PF transport from our
1317                  * list in case we don't find an active one.
1318                  */
1319                 if (trans->state == SCTP_PF) {
1320                         trans_pf = sctp_trans_elect_best(trans, trans_pf);
1321                         continue;
1322                 }
1323                 /* For active transports, pick the most recent ones. */
1324                 if (trans_pri == NULL ||
1325                     ktime_after(trans->last_time_heard,
1326                                 trans_pri->last_time_heard)) {
1327                         trans_sec = trans_pri;
1328                         trans_pri = trans;
1329                 } else if (trans_sec == NULL ||
1330                            ktime_after(trans->last_time_heard,
1331                                        trans_sec->last_time_heard)) {
1332                         trans_sec = trans;
1333                 }
1334         }
1335 
1336         /* RFC 2960 6.4 Multi-Homed SCTP Endpoints
1337          *
1338          * By default, an endpoint should always transmit to the primary
1339          * path, unless the SCTP user explicitly specifies the
1340          * destination transport address (and possibly source transport
1341          * address) to use. [If the primary is active but not most recent,
1342          * bump the most recently used transport.]
1343          */
1344         if ((asoc->peer.primary_path->state == SCTP_ACTIVE ||
1345              asoc->peer.primary_path->state == SCTP_UNKNOWN) &&
1346              asoc->peer.primary_path != trans_pri) {
1347                 trans_sec = trans_pri;
1348                 trans_pri = asoc->peer.primary_path;
1349         }
1350 
1351         /* We did not find anything useful for a possible retransmission
1352          * path; either primary path that we found is the the same as
1353          * the current one, or we didn't generally find an active one.
1354          */
1355         if (trans_sec == NULL)
1356                 trans_sec = trans_pri;
1357 
1358         /* If we failed to find a usable transport, just camp on the
1359          * active or pick a PF iff it's the better choice.
1360          */
1361         if (trans_pri == NULL) {
1362                 trans_pri = sctp_trans_elect_best(asoc->peer.active_path, trans_pf);
1363                 trans_sec = trans_pri;
1364         }
1365 
1366         /* Set the active and retran transports. */
1367         asoc->peer.active_path = trans_pri;
1368         asoc->peer.retran_path = trans_sec;
1369 }
1370 
1371 struct sctp_transport *
1372 sctp_assoc_choose_alter_transport(struct sctp_association *asoc,
1373                                   struct sctp_transport *last_sent_to)
1374 {
1375         /* If this is the first time packet is sent, use the active path,
1376          * else use the retran path. If the last packet was sent over the
1377          * retran path, update the retran path and use it.
1378          */
1379         if (last_sent_to == NULL) {
1380                 return asoc->peer.active_path;
1381         } else {
1382                 if (last_sent_to == asoc->peer.retran_path)
1383                         sctp_assoc_update_retran_path(asoc);
1384 
1385                 return asoc->peer.retran_path;
1386         }
1387 }
1388 
1389 /* Update the association's pmtu and frag_point by going through all the
1390  * transports. This routine is called when a transport's PMTU has changed.
1391  */
1392 void sctp_assoc_sync_pmtu(struct sock *sk, struct sctp_association *asoc)
1393 {
1394         struct sctp_transport *t;
1395         __u32 pmtu = 0;
1396 
1397         if (!asoc)
1398                 return;
1399 
1400         /* Get the lowest pmtu of all the transports. */
1401         list_for_each_entry(t, &asoc->peer.transport_addr_list,
1402                                 transports) {
1403                 if (t->pmtu_pending && t->dst) {
1404                         sctp_transport_update_pmtu(sk, t, dst_mtu(t->dst));
1405                         t->pmtu_pending = 0;
1406                 }
1407                 if (!pmtu || (t->pathmtu < pmtu))
1408                         pmtu = t->pathmtu;
1409         }
1410 
1411         if (pmtu) {
1412                 asoc->pathmtu = pmtu;
1413                 asoc->frag_point = sctp_frag_point(asoc, pmtu);
1414         }
1415 
1416         pr_debug("%s: asoc:%p, pmtu:%d, frag_point:%d\n", __func__, asoc,
1417                  asoc->pathmtu, asoc->frag_point);
1418 }
1419 
1420 /* Should we send a SACK to update our peer? */
1421 static inline bool sctp_peer_needs_update(struct sctp_association *asoc)
1422 {
1423         struct net *net = sock_net(asoc->base.sk);
1424         switch (asoc->state) {
1425         case SCTP_STATE_ESTABLISHED:
1426         case SCTP_STATE_SHUTDOWN_PENDING:
1427         case SCTP_STATE_SHUTDOWN_RECEIVED:
1428         case SCTP_STATE_SHUTDOWN_SENT:
1429                 if ((asoc->rwnd > asoc->a_rwnd) &&
1430                     ((asoc->rwnd - asoc->a_rwnd) >= max_t(__u32,
1431                            (asoc->base.sk->sk_rcvbuf >> net->sctp.rwnd_upd_shift),
1432                            asoc->pathmtu)))
1433                         return true;
1434                 break;
1435         default:
1436                 break;
1437         }
1438         return false;
1439 }
1440 
1441 /* Increase asoc's rwnd by len and send any window update SACK if needed. */
1442 void sctp_assoc_rwnd_increase(struct sctp_association *asoc, unsigned int len)
1443 {
1444         struct sctp_chunk *sack;
1445         struct timer_list *timer;
1446 
1447         if (asoc->rwnd_over) {
1448                 if (asoc->rwnd_over >= len) {
1449                         asoc->rwnd_over -= len;
1450                 } else {
1451                         asoc->rwnd += (len - asoc->rwnd_over);
1452                         asoc->rwnd_over = 0;
1453                 }
1454         } else {
1455                 asoc->rwnd += len;
1456         }
1457 
1458         /* If we had window pressure, start recovering it
1459          * once our rwnd had reached the accumulated pressure
1460          * threshold.  The idea is to recover slowly, but up
1461          * to the initial advertised window.
1462          */
1463         if (asoc->rwnd_press && asoc->rwnd >= asoc->rwnd_press) {
1464                 int change = min(asoc->pathmtu, asoc->rwnd_press);
1465                 asoc->rwnd += change;
1466                 asoc->rwnd_press -= change;
1467         }
1468 
1469         pr_debug("%s: asoc:%p rwnd increased by %d to (%u, %u) - %u\n",
1470                  __func__, asoc, len, asoc->rwnd, asoc->rwnd_over,
1471                  asoc->a_rwnd);
1472 
1473         /* Send a window update SACK if the rwnd has increased by at least the
1474          * minimum of the association's PMTU and half of the receive buffer.
1475          * The algorithm used is similar to the one described in
1476          * Section 4.2.3.3 of RFC 1122.
1477          */
1478         if (sctp_peer_needs_update(asoc)) {
1479                 asoc->a_rwnd = asoc->rwnd;
1480 
1481                 pr_debug("%s: sending window update SACK- asoc:%p rwnd:%u "
1482                          "a_rwnd:%u\n", __func__, asoc, asoc->rwnd,
1483                          asoc->a_rwnd);
1484 
1485                 sack = sctp_make_sack(asoc);
1486                 if (!sack)
1487                         return;
1488 
1489                 asoc->peer.sack_needed = 0;
1490 
1491                 sctp_outq_tail(&asoc->outqueue, sack);
1492 
1493                 /* Stop the SACK timer.  */
1494                 timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK];
1495                 if (del_timer(timer))
1496                         sctp_association_put(asoc);
1497         }
1498 }
1499 
1500 /* Decrease asoc's rwnd by len. */
1501 void sctp_assoc_rwnd_decrease(struct sctp_association *asoc, unsigned int len)
1502 {
1503         int rx_count;
1504         int over = 0;
1505 
1506         if (unlikely(!asoc->rwnd || asoc->rwnd_over))
1507                 pr_debug("%s: association:%p has asoc->rwnd:%u, "
1508                          "asoc->rwnd_over:%u!\n", __func__, asoc,
1509                          asoc->rwnd, asoc->rwnd_over);
1510 
1511         if (asoc->ep->rcvbuf_policy)
1512                 rx_count = atomic_read(&asoc->rmem_alloc);
1513         else
1514                 rx_count = atomic_read(&asoc->base.sk->sk_rmem_alloc);
1515 
1516         /* If we've reached or overflowed our receive buffer, announce
1517          * a 0 rwnd if rwnd would still be positive.  Store the
1518          * the potential pressure overflow so that the window can be restored
1519          * back to original value.
1520          */
1521         if (rx_count >= asoc->base.sk->sk_rcvbuf)
1522                 over = 1;
1523 
1524         if (asoc->rwnd >= len) {
1525                 asoc->rwnd -= len;
1526                 if (over) {
1527                         asoc->rwnd_press += asoc->rwnd;
1528                         asoc->rwnd = 0;
1529                 }
1530         } else {
1531                 asoc->rwnd_over = len - asoc->rwnd;
1532                 asoc->rwnd = 0;
1533         }
1534 
1535         pr_debug("%s: asoc:%p rwnd decreased by %d to (%u, %u, %u)\n",
1536                  __func__, asoc, len, asoc->rwnd, asoc->rwnd_over,
1537                  asoc->rwnd_press);
1538 }
1539 
1540 /* Build the bind address list for the association based on info from the
1541  * local endpoint and the remote peer.
1542  */
1543 int sctp_assoc_set_bind_addr_from_ep(struct sctp_association *asoc,
1544                                      sctp_scope_t scope, gfp_t gfp)
1545 {
1546         int flags;
1547 
1548         /* Use scoping rules to determine the subset of addresses from
1549          * the endpoint.
1550          */
1551         flags = (PF_INET6 == asoc->base.sk->sk_family) ? SCTP_ADDR6_ALLOWED : 0;
1552         if (asoc->peer.ipv4_address)
1553                 flags |= SCTP_ADDR4_PEERSUPP;
1554         if (asoc->peer.ipv6_address)
1555                 flags |= SCTP_ADDR6_PEERSUPP;
1556 
1557         return sctp_bind_addr_copy(sock_net(asoc->base.sk),
1558                                    &asoc->base.bind_addr,
1559                                    &asoc->ep->base.bind_addr,
1560                                    scope, gfp, flags);
1561 }
1562 
1563 /* Build the association's bind address list from the cookie.  */
1564 int sctp_assoc_set_bind_addr_from_cookie(struct sctp_association *asoc,
1565                                          struct sctp_cookie *cookie,
1566                                          gfp_t gfp)
1567 {
1568         int var_size2 = ntohs(cookie->peer_init->chunk_hdr.length);
1569         int var_size3 = cookie->raw_addr_list_len;
1570         __u8 *raw = (__u8 *)cookie->peer_init + var_size2;
1571 
1572         return sctp_raw_to_bind_addrs(&asoc->base.bind_addr, raw, var_size3,
1573                                       asoc->ep->base.bind_addr.port, gfp);
1574 }
1575 
1576 /* Lookup laddr in the bind address list of an association. */
1577 int sctp_assoc_lookup_laddr(struct sctp_association *asoc,
1578                             const union sctp_addr *laddr)
1579 {
1580         int found = 0;
1581 
1582         if ((asoc->base.bind_addr.port == ntohs(laddr->v4.sin_port)) &&
1583             sctp_bind_addr_match(&asoc->base.bind_addr, laddr,
1584                                  sctp_sk(asoc->base.sk)))
1585                 found = 1;
1586 
1587         return found;
1588 }
1589 
1590 /* Set an association id for a given association */
1591 int sctp_assoc_set_id(struct sctp_association *asoc, gfp_t gfp)
1592 {
1593         bool preload = !!(gfp & __GFP_WAIT);
1594         int ret;
1595 
1596         /* If the id is already assigned, keep it. */
1597         if (asoc->assoc_id)
1598                 return 0;
1599 
1600         if (preload)
1601                 idr_preload(gfp);
1602         spin_lock_bh(&sctp_assocs_id_lock);
1603         /* 0 is not a valid assoc_id, must be >= 1 */
1604         ret = idr_alloc_cyclic(&sctp_assocs_id, asoc, 1, 0, GFP_NOWAIT);
1605         spin_unlock_bh(&sctp_assocs_id_lock);
1606         if (preload)
1607                 idr_preload_end();
1608         if (ret < 0)
1609                 return ret;
1610 
1611         asoc->assoc_id = (sctp_assoc_t)ret;
1612         return 0;
1613 }
1614 
1615 /* Free the ASCONF queue */
1616 static void sctp_assoc_free_asconf_queue(struct sctp_association *asoc)
1617 {
1618         struct sctp_chunk *asconf;
1619         struct sctp_chunk *tmp;
1620 
1621         list_for_each_entry_safe(asconf, tmp, &asoc->addip_chunk_list, list) {
1622                 list_del_init(&asconf->list);
1623                 sctp_chunk_free(asconf);
1624         }
1625 }
1626 
1627 /* Free asconf_ack cache */
1628 static void sctp_assoc_free_asconf_acks(struct sctp_association *asoc)
1629 {
1630         struct sctp_chunk *ack;
1631         struct sctp_chunk *tmp;
1632 
1633         list_for_each_entry_safe(ack, tmp, &asoc->asconf_ack_list,
1634                                 transmitted_list) {
1635                 list_del_init(&ack->transmitted_list);
1636                 sctp_chunk_free(ack);
1637         }
1638 }
1639 
1640 /* Clean up the ASCONF_ACK queue */
1641 void sctp_assoc_clean_asconf_ack_cache(const struct sctp_association *asoc)
1642 {
1643         struct sctp_chunk *ack;
1644         struct sctp_chunk *tmp;
1645 
1646         /* We can remove all the entries from the queue up to
1647          * the "Peer-Sequence-Number".
1648          */
1649         list_for_each_entry_safe(ack, tmp, &asoc->asconf_ack_list,
1650                                 transmitted_list) {
1651                 if (ack->subh.addip_hdr->serial ==
1652                                 htonl(asoc->peer.addip_serial))
1653                         break;
1654 
1655                 list_del_init(&ack->transmitted_list);
1656                 sctp_chunk_free(ack);
1657         }
1658 }
1659 
1660 /* Find the ASCONF_ACK whose serial number matches ASCONF */
1661 struct sctp_chunk *sctp_assoc_lookup_asconf_ack(
1662                                         const struct sctp_association *asoc,
1663                                         __be32 serial)
1664 {
1665         struct sctp_chunk *ack;
1666 
1667         /* Walk through the list of cached ASCONF-ACKs and find the
1668          * ack chunk whose serial number matches that of the request.
1669          */
1670         list_for_each_entry(ack, &asoc->asconf_ack_list, transmitted_list) {
1671                 if (sctp_chunk_pending(ack))
1672                         continue;
1673                 if (ack->subh.addip_hdr->serial == serial) {
1674                         sctp_chunk_hold(ack);
1675                         return ack;
1676                 }
1677         }
1678 
1679         return NULL;
1680 }
1681 
1682 void sctp_asconf_queue_teardown(struct sctp_association *asoc)
1683 {
1684         /* Free any cached ASCONF_ACK chunk. */
1685         sctp_assoc_free_asconf_acks(asoc);
1686 
1687         /* Free the ASCONF queue. */
1688         sctp_assoc_free_asconf_queue(asoc);
1689 
1690         /* Free any cached ASCONF chunk. */
1691         if (asoc->addip_last_asconf)
1692                 sctp_chunk_free(asoc->addip_last_asconf);
1693 }
1694 

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