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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 struct sctp_paramhdr *p;
75 int i;
76
77 /* Retrieve the SCTP per socket area. */
78 sp = sctp_sk((struct sock *)sk);
79
80 /* Discarding const is appropriate here. */
81 asoc->ep = (struct sctp_endpoint *)ep;
82 asoc->base.sk = (struct sock *)sk;
83
84 sctp_endpoint_hold(asoc->ep);
85 sock_hold(asoc->base.sk);
86
87 /* Initialize the common base substructure. */
88 asoc->base.type = SCTP_EP_TYPE_ASSOCIATION;
89
90 /* Initialize the object handling fields. */
91 refcount_set(&asoc->base.refcnt, 1);
92
93 /* Initialize the bind addr area. */
94 sctp_bind_addr_init(&asoc->base.bind_addr, ep->base.bind_addr.port);
95
96 asoc->state = SCTP_STATE_CLOSED;
97 asoc->cookie_life = ms_to_ktime(sp->assocparams.sasoc_cookie_life);
98 asoc->user_frag = sp->user_frag;
99
100 /* Set the association max_retrans and RTO values from the
101 * socket values.
102 */
103 asoc->max_retrans = sp->assocparams.sasoc_asocmaxrxt;
104 asoc->pf_retrans = net->sctp.pf_retrans;
105
106 asoc->rto_initial = msecs_to_jiffies(sp->rtoinfo.srto_initial);
107 asoc->rto_max = msecs_to_jiffies(sp->rtoinfo.srto_max);
108 asoc->rto_min = msecs_to_jiffies(sp->rtoinfo.srto_min);
109
110 /* Initialize the association's heartbeat interval based on the
111 * sock configured value.
112 */
113 asoc->hbinterval = msecs_to_jiffies(sp->hbinterval);
114
115 /* Initialize path max retrans value. */
116 asoc->pathmaxrxt = sp->pathmaxrxt;
117
118 /* Initialize default path MTU. */
119 asoc->pathmtu = sp->pathmtu;
120
121 /* Set association default SACK delay */
122 asoc->sackdelay = msecs_to_jiffies(sp->sackdelay);
123 asoc->sackfreq = sp->sackfreq;
124
125 /* Set the association default flags controlling
126 * Heartbeat, SACK delay, and Path MTU Discovery.
127 */
128 asoc->param_flags = sp->param_flags;
129
130 /* Initialize the maximum number of new data packets that can be sent
131 * in a burst.
132 */
133 asoc->max_burst = sp->max_burst;
134
135 /* initialize association timers */
136 asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_COOKIE] = asoc->rto_initial;
137 asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_INIT] = asoc->rto_initial;
138 asoc->timeouts[SCTP_EVENT_TIMEOUT_T2_SHUTDOWN] = asoc->rto_initial;
139
140 /* sctpimpguide Section 2.12.2
141 * If the 'T5-shutdown-guard' timer is used, it SHOULD be set to the
142 * recommended value of 5 times 'RTO.Max'.
143 */
144 asoc->timeouts[SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]
145 = 5 * asoc->rto_max;
146
147 asoc->timeouts[SCTP_EVENT_TIMEOUT_SACK] = asoc->sackdelay;
148 asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE] = sp->autoclose * HZ;
149
150 /* Initializes the timers */
151 for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i)
152 setup_timer(&asoc->timers[i], sctp_timer_events[i],
153 (unsigned long)asoc);
154
155 /* Pull default initialization values from the sock options.
156 * Note: This assumes that the values have already been
157 * validated in the sock.
158 */
159 asoc->c.sinit_max_instreams = sp->initmsg.sinit_max_instreams;
160 asoc->c.sinit_num_ostreams = sp->initmsg.sinit_num_ostreams;
161 asoc->max_init_attempts = sp->initmsg.sinit_max_attempts;
162
163 asoc->max_init_timeo =
164 msecs_to_jiffies(sp->initmsg.sinit_max_init_timeo);
165
166 /* Set the local window size for receive.
167 * This is also the rcvbuf space per association.
168 * RFC 6 - A SCTP receiver MUST be able to receive a minimum of
169 * 1500 bytes in one SCTP packet.
170 */
171 if ((sk->sk_rcvbuf/2) < SCTP_DEFAULT_MINWINDOW)
172 asoc->rwnd = SCTP_DEFAULT_MINWINDOW;
173 else
174 asoc->rwnd = sk->sk_rcvbuf/2;
175
176 asoc->a_rwnd = asoc->rwnd;
177
178 /* Use my own max window until I learn something better. */
179 asoc->peer.rwnd = SCTP_DEFAULT_MAXWINDOW;
180
181 /* Initialize the receive memory counter */
182 atomic_set(&asoc->rmem_alloc, 0);
183
184 init_waitqueue_head(&asoc->wait);
185
186 asoc->c.my_vtag = sctp_generate_tag(ep);
187 asoc->c.my_port = ep->base.bind_addr.port;
188
189 asoc->c.initial_tsn = sctp_generate_tsn(ep);
190
191 asoc->next_tsn = asoc->c.initial_tsn;
192
193 asoc->ctsn_ack_point = asoc->next_tsn - 1;
194 asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
195 asoc->highest_sacked = asoc->ctsn_ack_point;
196 asoc->last_cwr_tsn = asoc->ctsn_ack_point;
197
198 /* ADDIP Section 4.1 Asconf Chunk Procedures
199 *
200 * When an endpoint has an ASCONF signaled change to be sent to the
201 * remote endpoint it should do the following:
202 * ...
203 * A2) a serial number should be assigned to the chunk. The serial
204 * number SHOULD be a monotonically increasing number. The serial
205 * numbers SHOULD be initialized at the start of the
206 * association to the same value as the initial TSN.
207 */
208 asoc->addip_serial = asoc->c.initial_tsn;
209 asoc->strreset_outseq = 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 if (sctp_stream_init(&asoc->stream, asoc->c.sinit_num_ostreams,
250 0, gfp))
251 goto fail_init;
252
253 /* Assume that peer would support both address types unless we are
254 * told otherwise.
255 */
256 asoc->peer.ipv4_address = 1;
257 if (asoc->base.sk->sk_family == PF_INET6)
258 asoc->peer.ipv6_address = 1;
259 INIT_LIST_HEAD(&asoc->asocs);
260
261 asoc->default_stream = sp->default_stream;
262 asoc->default_ppid = sp->default_ppid;
263 asoc->default_flags = sp->default_flags;
264 asoc->default_context = sp->default_context;
265 asoc->default_timetolive = sp->default_timetolive;
266 asoc->default_rcv_context = sp->default_rcv_context;
267
268 /* AUTH related initializations */
269 INIT_LIST_HEAD(&asoc->endpoint_shared_keys);
270 if (sctp_auth_asoc_copy_shkeys(ep, asoc, gfp))
271 goto stream_free;
272
273 asoc->active_key_id = ep->active_key_id;
274 asoc->prsctp_enable = ep->prsctp_enable;
275 asoc->reconf_enable = ep->reconf_enable;
276 asoc->strreset_enable = ep->strreset_enable;
277
278 /* Save the hmacs and chunks list into this association */
279 if (ep->auth_hmacs_list)
280 memcpy(asoc->c.auth_hmacs, ep->auth_hmacs_list,
281 ntohs(ep->auth_hmacs_list->param_hdr.length));
282 if (ep->auth_chunk_list)
283 memcpy(asoc->c.auth_chunks, ep->auth_chunk_list,
284 ntohs(ep->auth_chunk_list->param_hdr.length));
285
286 /* Get the AUTH random number for this association */
287 p = (struct sctp_paramhdr *)asoc->c.auth_random;
288 p->type = SCTP_PARAM_RANDOM;
289 p->length = htons(sizeof(*p) + SCTP_AUTH_RANDOM_LENGTH);
290 get_random_bytes(p+1, SCTP_AUTH_RANDOM_LENGTH);
291
292 return asoc;
293
294 stream_free:
295 sctp_stream_free(&asoc->stream);
296 fail_init:
297 sock_put(asoc->base.sk);
298 sctp_endpoint_put(asoc->ep);
299 return NULL;
300 }
301
302 /* Allocate and initialize a new association */
303 struct sctp_association *sctp_association_new(const struct sctp_endpoint *ep,
304 const struct sock *sk,
305 sctp_scope_t scope,
306 gfp_t gfp)
307 {
308 struct sctp_association *asoc;
309
310 asoc = kzalloc(sizeof(*asoc), gfp);
311 if (!asoc)
312 goto fail;
313
314 if (!sctp_association_init(asoc, ep, sk, scope, gfp))
315 goto fail_init;
316
317 SCTP_DBG_OBJCNT_INC(assoc);
318
319 pr_debug("Created asoc %p\n", asoc);
320
321 return asoc;
322
323 fail_init:
324 kfree(asoc);
325 fail:
326 return NULL;
327 }
328
329 /* Free this association if possible. There may still be users, so
330 * the actual deallocation may be delayed.
331 */
332 void sctp_association_free(struct sctp_association *asoc)
333 {
334 struct sock *sk = asoc->base.sk;
335 struct sctp_transport *transport;
336 struct list_head *pos, *temp;
337 int i;
338
339 /* Only real associations count against the endpoint, so
340 * don't bother for if this is a temporary association.
341 */
342 if (!list_empty(&asoc->asocs)) {
343 list_del(&asoc->asocs);
344
345 /* Decrement the backlog value for a TCP-style listening
346 * socket.
347 */
348 if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
349 sk->sk_ack_backlog--;
350 }
351
352 /* Mark as dead, so other users can know this structure is
353 * going away.
354 */
355 asoc->base.dead = true;
356
357 /* Dispose of any data lying around in the outqueue. */
358 sctp_outq_free(&asoc->outqueue);
359
360 /* Dispose of any pending messages for the upper layer. */
361 sctp_ulpq_free(&asoc->ulpq);
362
363 /* Dispose of any pending chunks on the inqueue. */
364 sctp_inq_free(&asoc->base.inqueue);
365
366 sctp_tsnmap_free(&asoc->peer.tsn_map);
367
368 /* Free stream information. */
369 sctp_stream_free(&asoc->stream);
370
371 if (asoc->strreset_chunk)
372 sctp_chunk_free(asoc->strreset_chunk);
373
374 /* Clean up the bound address list. */
375 sctp_bind_addr_free(&asoc->base.bind_addr);
376
377 /* Do we need to go through all of our timers and
378 * delete them? To be safe we will try to delete all, but we
379 * should be able to go through and make a guess based
380 * on our state.
381 */
382 for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i) {
383 if (del_timer(&asoc->timers[i]))
384 sctp_association_put(asoc);
385 }
386
387 /* Free peer's cached cookie. */
388 kfree(asoc->peer.cookie);
389 kfree(asoc->peer.peer_random);
390 kfree(asoc->peer.peer_chunks);
391 kfree(asoc->peer.peer_hmacs);
392
393 /* Release the transport structures. */
394 list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
395 transport = list_entry(pos, struct sctp_transport, transports);
396 list_del_rcu(pos);
397 sctp_unhash_transport(transport);
398 sctp_transport_free(transport);
399 }
400
401 asoc->peer.transport_count = 0;
402
403 sctp_asconf_queue_teardown(asoc);
404
405 /* Free pending address space being deleted */
406 kfree(asoc->asconf_addr_del_pending);
407
408 /* AUTH - Free the endpoint shared keys */
409 sctp_auth_destroy_keys(&asoc->endpoint_shared_keys);
410
411 /* AUTH - Free the association shared key */
412 sctp_auth_key_put(asoc->asoc_shared_key);
413
414 sctp_association_put(asoc);
415 }
416
417 /* Cleanup and free up an association. */
418 static void sctp_association_destroy(struct sctp_association *asoc)
419 {
420 if (unlikely(!asoc->base.dead)) {
421 WARN(1, "Attempt to destroy undead association %p!\n", asoc);
422 return;
423 }
424
425 sctp_endpoint_put(asoc->ep);
426 sock_put(asoc->base.sk);
427
428 if (asoc->assoc_id != 0) {
429 spin_lock_bh(&sctp_assocs_id_lock);
430 idr_remove(&sctp_assocs_id, asoc->assoc_id);
431 spin_unlock_bh(&sctp_assocs_id_lock);
432 }
433
434 WARN_ON(atomic_read(&asoc->rmem_alloc));
435
436 kfree(asoc);
437 SCTP_DBG_OBJCNT_DEC(assoc);
438 }
439
440 /* Change the primary destination address for the peer. */
441 void sctp_assoc_set_primary(struct sctp_association *asoc,
442 struct sctp_transport *transport)
443 {
444 int changeover = 0;
445
446 /* it's a changeover only if we already have a primary path
447 * that we are changing
448 */
449 if (asoc->peer.primary_path != NULL &&
450 asoc->peer.primary_path != transport)
451 changeover = 1 ;
452
453 asoc->peer.primary_path = transport;
454
455 /* Set a default msg_name for events. */
456 memcpy(&asoc->peer.primary_addr, &transport->ipaddr,
457 sizeof(union sctp_addr));
458
459 /* If the primary path is changing, assume that the
460 * user wants to use this new path.
461 */
462 if ((transport->state == SCTP_ACTIVE) ||
463 (transport->state == SCTP_UNKNOWN))
464 asoc->peer.active_path = transport;
465
466 /*
467 * SFR-CACC algorithm:
468 * Upon the receipt of a request to change the primary
469 * destination address, on the data structure for the new
470 * primary destination, the sender MUST do the following:
471 *
472 * 1) If CHANGEOVER_ACTIVE is set, then there was a switch
473 * to this destination address earlier. The sender MUST set
474 * CYCLING_CHANGEOVER to indicate that this switch is a
475 * double switch to the same destination address.
476 *
477 * Really, only bother is we have data queued or outstanding on
478 * the association.
479 */
480 if (!asoc->outqueue.outstanding_bytes && !asoc->outqueue.out_qlen)
481 return;
482
483 if (transport->cacc.changeover_active)
484 transport->cacc.cycling_changeover = changeover;
485
486 /* 2) The sender MUST set CHANGEOVER_ACTIVE to indicate that
487 * a changeover has occurred.
488 */
489 transport->cacc.changeover_active = changeover;
490
491 /* 3) The sender MUST store the next TSN to be sent in
492 * next_tsn_at_change.
493 */
494 transport->cacc.next_tsn_at_change = asoc->next_tsn;
495 }
496
497 /* Remove a transport from an association. */
498 void sctp_assoc_rm_peer(struct sctp_association *asoc,
499 struct sctp_transport *peer)
500 {
501 struct list_head *pos;
502 struct sctp_transport *transport;
503
504 pr_debug("%s: association:%p addr:%pISpc\n",
505 __func__, asoc, &peer->ipaddr.sa);
506
507 /* If we are to remove the current retran_path, update it
508 * to the next peer before removing this peer from the list.
509 */
510 if (asoc->peer.retran_path == peer)
511 sctp_assoc_update_retran_path(asoc);
512
513 /* Remove this peer from the list. */
514 list_del_rcu(&peer->transports);
515 /* Remove this peer from the transport hashtable */
516 sctp_unhash_transport(peer);
517
518 /* Get the first transport of asoc. */
519 pos = asoc->peer.transport_addr_list.next;
520 transport = list_entry(pos, struct sctp_transport, transports);
521
522 /* Update any entries that match the peer to be deleted. */
523 if (asoc->peer.primary_path == peer)
524 sctp_assoc_set_primary(asoc, transport);
525 if (asoc->peer.active_path == peer)
526 asoc->peer.active_path = transport;
527 if (asoc->peer.retran_path == peer)
528 asoc->peer.retran_path = transport;
529 if (asoc->peer.last_data_from == peer)
530 asoc->peer.last_data_from = transport;
531
532 if (asoc->strreset_chunk &&
533 asoc->strreset_chunk->transport == peer) {
534 asoc->strreset_chunk->transport = transport;
535 sctp_transport_reset_reconf_timer(transport);
536 }
537
538 /* If we remove the transport an INIT was last sent to, set it to
539 * NULL. Combined with the update of the retran path above, this
540 * will cause the next INIT to be sent to the next available
541 * transport, maintaining the cycle.
542 */
543 if (asoc->init_last_sent_to == peer)
544 asoc->init_last_sent_to = NULL;
545
546 /* If we remove the transport an SHUTDOWN was last sent to, set it
547 * to NULL. Combined with the update of the retran path above, this
548 * will cause the next SHUTDOWN to be sent to the next available
549 * transport, maintaining the cycle.
550 */
551 if (asoc->shutdown_last_sent_to == peer)
552 asoc->shutdown_last_sent_to = NULL;
553
554 /* If we remove the transport an ASCONF was last sent to, set it to
555 * NULL.
556 */
557 if (asoc->addip_last_asconf &&
558 asoc->addip_last_asconf->transport == peer)
559 asoc->addip_last_asconf->transport = NULL;
560
561 /* If we have something on the transmitted list, we have to
562 * save it off. The best place is the active path.
563 */
564 if (!list_empty(&peer->transmitted)) {
565 struct sctp_transport *active = asoc->peer.active_path;
566 struct sctp_chunk *ch;
567
568 /* Reset the transport of each chunk on this list */
569 list_for_each_entry(ch, &peer->transmitted,
570 transmitted_list) {
571 ch->transport = NULL;
572 ch->rtt_in_progress = 0;
573 }
574
575 list_splice_tail_init(&peer->transmitted,
576 &active->transmitted);
577
578 /* Start a T3 timer here in case it wasn't running so
579 * that these migrated packets have a chance to get
580 * retransmitted.
581 */
582 if (!timer_pending(&active->T3_rtx_timer))
583 if (!mod_timer(&active->T3_rtx_timer,
584 jiffies + active->rto))
585 sctp_transport_hold(active);
586 }
587
588 asoc->peer.transport_count--;
589
590 sctp_transport_free(peer);
591 }
592
593 /* Add a transport address to an association. */
594 struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc,
595 const union sctp_addr *addr,
596 const gfp_t gfp,
597 const int peer_state)
598 {
599 struct net *net = sock_net(asoc->base.sk);
600 struct sctp_transport *peer;
601 struct sctp_sock *sp;
602 unsigned short port;
603
604 sp = sctp_sk(asoc->base.sk);
605
606 /* AF_INET and AF_INET6 share common port field. */
607 port = ntohs(addr->v4.sin_port);
608
609 pr_debug("%s: association:%p addr:%pISpc state:%d\n", __func__,
610 asoc, &addr->sa, peer_state);
611
612 /* Set the port if it has not been set yet. */
613 if (0 == asoc->peer.port)
614 asoc->peer.port = port;
615
616 /* Check to see if this is a duplicate. */
617 peer = sctp_assoc_lookup_paddr(asoc, addr);
618 if (peer) {
619 /* An UNKNOWN state is only set on transports added by
620 * user in sctp_connectx() call. Such transports should be
621 * considered CONFIRMED per RFC 4960, Section 5.4.
622 */
623 if (peer->state == SCTP_UNKNOWN) {
624 peer->state = SCTP_ACTIVE;
625 }
626 return peer;
627 }
628
629 peer = sctp_transport_new(net, addr, gfp);
630 if (!peer)
631 return NULL;
632
633 sctp_transport_set_owner(peer, asoc);
634
635 /* Initialize the peer's heartbeat interval based on the
636 * association configured value.
637 */
638 peer->hbinterval = asoc->hbinterval;
639
640 /* Set the path max_retrans. */
641 peer->pathmaxrxt = asoc->pathmaxrxt;
642
643 /* And the partial failure retrans threshold */
644 peer->pf_retrans = asoc->pf_retrans;
645
646 /* Initialize the peer's SACK delay timeout based on the
647 * association configured value.
648 */
649 peer->sackdelay = asoc->sackdelay;
650 peer->sackfreq = asoc->sackfreq;
651
652 /* Enable/disable heartbeat, SACK delay, and path MTU discovery
653 * based on association setting.
654 */
655 peer->param_flags = asoc->param_flags;
656
657 sctp_transport_route(peer, NULL, sp);
658
659 /* Initialize the pmtu of the transport. */
660 if (peer->param_flags & SPP_PMTUD_DISABLE) {
661 if (asoc->pathmtu)
662 peer->pathmtu = asoc->pathmtu;
663 else
664 peer->pathmtu = SCTP_DEFAULT_MAXSEGMENT;
665 }
666
667 /* If this is the first transport addr on this association,
668 * initialize the association PMTU to the peer's PMTU.
669 * If not and the current association PMTU is higher than the new
670 * peer's PMTU, reset the association PMTU to the new peer's PMTU.
671 */
672 if (asoc->pathmtu)
673 asoc->pathmtu = min_t(int, peer->pathmtu, asoc->pathmtu);
674 else
675 asoc->pathmtu = peer->pathmtu;
676
677 pr_debug("%s: association:%p PMTU set to %d\n", __func__, asoc,
678 asoc->pathmtu);
679
680 peer->pmtu_pending = 0;
681
682 asoc->frag_point = sctp_frag_point(asoc, asoc->pathmtu);
683
684 /* The asoc->peer.port might not be meaningful yet, but
685 * initialize the packet structure anyway.
686 */
687 sctp_packet_init(&peer->packet, peer, asoc->base.bind_addr.port,
688 asoc->peer.port);
689
690 /* 7.2.1 Slow-Start
691 *
692 * o The initial cwnd before DATA transmission or after a sufficiently
693 * long idle period MUST be set to
694 * min(4*MTU, max(2*MTU, 4380 bytes))
695 *
696 * o The initial value of ssthresh MAY be arbitrarily high
697 * (for example, implementations MAY use the size of the
698 * receiver advertised window).
699 */
700 peer->cwnd = min(4*asoc->pathmtu, max_t(__u32, 2*asoc->pathmtu, 4380));
701
702 /* At this point, we may not have the receiver's advertised window,
703 * so initialize ssthresh to the default value and it will be set
704 * later when we process the INIT.
705 */
706 peer->ssthresh = SCTP_DEFAULT_MAXWINDOW;
707
708 peer->partial_bytes_acked = 0;
709 peer->flight_size = 0;
710 peer->burst_limited = 0;
711
712 /* Set the transport's RTO.initial value */
713 peer->rto = asoc->rto_initial;
714 sctp_max_rto(asoc, peer);
715
716 /* Set the peer's active state. */
717 peer->state = peer_state;
718
719 /* Add this peer into the transport hashtable */
720 if (sctp_hash_transport(peer)) {
721 sctp_transport_free(peer);
722 return NULL;
723 }
724
725 /* Attach the remote transport to our asoc. */
726 list_add_tail_rcu(&peer->transports, &asoc->peer.transport_addr_list);
727 asoc->peer.transport_count++;
728
729 /* If we do not yet have a primary path, set one. */
730 if (!asoc->peer.primary_path) {
731 sctp_assoc_set_primary(asoc, peer);
732 asoc->peer.retran_path = peer;
733 }
734
735 if (asoc->peer.active_path == asoc->peer.retran_path &&
736 peer->state != SCTP_UNCONFIRMED) {
737 asoc->peer.retran_path = peer;
738 }
739
740 return peer;
741 }
742
743 /* Delete a transport address from an association. */
744 void sctp_assoc_del_peer(struct sctp_association *asoc,
745 const union sctp_addr *addr)
746 {
747 struct list_head *pos;
748 struct list_head *temp;
749 struct sctp_transport *transport;
750
751 list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
752 transport = list_entry(pos, struct sctp_transport, transports);
753 if (sctp_cmp_addr_exact(addr, &transport->ipaddr)) {
754 /* Do book keeping for removing the peer and free it. */
755 sctp_assoc_rm_peer(asoc, transport);
756 break;
757 }
758 }
759 }
760
761 /* Lookup a transport by address. */
762 struct sctp_transport *sctp_assoc_lookup_paddr(
763 const struct sctp_association *asoc,
764 const union sctp_addr *address)
765 {
766 struct sctp_transport *t;
767
768 /* Cycle through all transports searching for a peer address. */
769
770 list_for_each_entry(t, &asoc->peer.transport_addr_list,
771 transports) {
772 if (sctp_cmp_addr_exact(address, &t->ipaddr))
773 return t;
774 }
775
776 return NULL;
777 }
778
779 /* Remove all transports except a give one */
780 void sctp_assoc_del_nonprimary_peers(struct sctp_association *asoc,
781 struct sctp_transport *primary)
782 {
783 struct sctp_transport *temp;
784 struct sctp_transport *t;
785
786 list_for_each_entry_safe(t, temp, &asoc->peer.transport_addr_list,
787 transports) {
788 /* if the current transport is not the primary one, delete it */
789 if (t != primary)
790 sctp_assoc_rm_peer(asoc, t);
791 }
792 }
793
794 /* Engage in transport control operations.
795 * Mark the transport up or down and send a notification to the user.
796 * Select and update the new active and retran paths.
797 */
798 void sctp_assoc_control_transport(struct sctp_association *asoc,
799 struct sctp_transport *transport,
800 sctp_transport_cmd_t command,
801 sctp_sn_error_t error)
802 {
803 struct sctp_ulpevent *event;
804 struct sockaddr_storage addr;
805 int spc_state = 0;
806 bool ulp_notify = true;
807
808 /* Record the transition on the transport. */
809 switch (command) {
810 case SCTP_TRANSPORT_UP:
811 /* If we are moving from UNCONFIRMED state due
812 * to heartbeat success, report the SCTP_ADDR_CONFIRMED
813 * state to the user, otherwise report SCTP_ADDR_AVAILABLE.
814 */
815 if (SCTP_UNCONFIRMED == transport->state &&
816 SCTP_HEARTBEAT_SUCCESS == error)
817 spc_state = SCTP_ADDR_CONFIRMED;
818 else
819 spc_state = SCTP_ADDR_AVAILABLE;
820 /* Don't inform ULP about transition from PF to
821 * active state and set cwnd to 1 MTU, see SCTP
822 * Quick failover draft section 5.1, point 5
823 */
824 if (transport->state == SCTP_PF) {
825 ulp_notify = false;
826 transport->cwnd = asoc->pathmtu;
827 }
828 transport->state = SCTP_ACTIVE;
829 break;
830
831 case SCTP_TRANSPORT_DOWN:
832 /* If the transport was never confirmed, do not transition it
833 * to inactive state. Also, release the cached route since
834 * there may be a better route next time.
835 */
836 if (transport->state != SCTP_UNCONFIRMED)
837 transport->state = SCTP_INACTIVE;
838 else {
839 sctp_transport_dst_release(transport);
840 ulp_notify = false;
841 }
842
843 spc_state = SCTP_ADDR_UNREACHABLE;
844 break;
845
846 case SCTP_TRANSPORT_PF:
847 transport->state = SCTP_PF;
848 ulp_notify = false;
849 break;
850
851 default:
852 return;
853 }
854
855 /* Generate and send a SCTP_PEER_ADDR_CHANGE notification
856 * to the user.
857 */
858 if (ulp_notify) {
859 memset(&addr, 0, sizeof(struct sockaddr_storage));
860 memcpy(&addr, &transport->ipaddr,
861 transport->af_specific->sockaddr_len);
862
863 event = sctp_ulpevent_make_peer_addr_change(asoc, &addr,
864 0, spc_state, error, GFP_ATOMIC);
865 if (event)
866 sctp_ulpq_tail_event(&asoc->ulpq, event);
867 }
868
869 /* Select new active and retran paths. */
870 sctp_select_active_and_retran_path(asoc);
871 }
872
873 /* Hold a reference to an association. */
874 void sctp_association_hold(struct sctp_association *asoc)
875 {
876 refcount_inc(&asoc->base.refcnt);
877 }
878
879 /* Release a reference to an association and cleanup
880 * if there are no more references.
881 */
882 void sctp_association_put(struct sctp_association *asoc)
883 {
884 if (refcount_dec_and_test(&asoc->base.refcnt))
885 sctp_association_destroy(asoc);
886 }
887
888 /* Allocate the next TSN, Transmission Sequence Number, for the given
889 * association.
890 */
891 __u32 sctp_association_get_next_tsn(struct sctp_association *asoc)
892 {
893 /* From Section 1.6 Serial Number Arithmetic:
894 * Transmission Sequence Numbers wrap around when they reach
895 * 2**32 - 1. That is, the next TSN a DATA chunk MUST use
896 * after transmitting TSN = 2*32 - 1 is TSN = 0.
897 */
898 __u32 retval = asoc->next_tsn;
899 asoc->next_tsn++;
900 asoc->unack_data++;
901
902 return retval;
903 }
904
905 /* Compare two addresses to see if they match. Wildcard addresses
906 * only match themselves.
907 */
908 int sctp_cmp_addr_exact(const union sctp_addr *ss1,
909 const union sctp_addr *ss2)
910 {
911 struct sctp_af *af;
912
913 af = sctp_get_af_specific(ss1->sa.sa_family);
914 if (unlikely(!af))
915 return 0;
916
917 return af->cmp_addr(ss1, ss2);
918 }
919
920 /* Return an ecne chunk to get prepended to a packet.
921 * Note: We are sly and return a shared, prealloced chunk. FIXME:
922 * No we don't, but we could/should.
923 */
924 struct sctp_chunk *sctp_get_ecne_prepend(struct sctp_association *asoc)
925 {
926 if (!asoc->need_ecne)
927 return NULL;
928
929 /* Send ECNE if needed.
930 * Not being able to allocate a chunk here is not deadly.
931 */
932 return sctp_make_ecne(asoc, asoc->last_ecne_tsn);
933 }
934
935 /*
936 * Find which transport this TSN was sent on.
937 */
938 struct sctp_transport *sctp_assoc_lookup_tsn(struct sctp_association *asoc,
939 __u32 tsn)
940 {
941 struct sctp_transport *active;
942 struct sctp_transport *match;
943 struct sctp_transport *transport;
944 struct sctp_chunk *chunk;
945 __be32 key = htonl(tsn);
946
947 match = NULL;
948
949 /*
950 * FIXME: In general, find a more efficient data structure for
951 * searching.
952 */
953
954 /*
955 * The general strategy is to search each transport's transmitted
956 * list. Return which transport this TSN lives on.
957 *
958 * Let's be hopeful and check the active_path first.
959 * Another optimization would be to know if there is only one
960 * outbound path and not have to look for the TSN at all.
961 *
962 */
963
964 active = asoc->peer.active_path;
965
966 list_for_each_entry(chunk, &active->transmitted,
967 transmitted_list) {
968
969 if (key == chunk->subh.data_hdr->tsn) {
970 match = active;
971 goto out;
972 }
973 }
974
975 /* If not found, go search all the other transports. */
976 list_for_each_entry(transport, &asoc->peer.transport_addr_list,
977 transports) {
978
979 if (transport == active)
980 continue;
981 list_for_each_entry(chunk, &transport->transmitted,
982 transmitted_list) {
983 if (key == chunk->subh.data_hdr->tsn) {
984 match = transport;
985 goto out;
986 }
987 }
988 }
989 out:
990 return match;
991 }
992
993 /* Is this the association we are looking for? */
994 struct sctp_transport *sctp_assoc_is_match(struct sctp_association *asoc,
995 struct net *net,
996 const union sctp_addr *laddr,
997 const union sctp_addr *paddr)
998 {
999 struct sctp_transport *transport;
1000
1001 if ((htons(asoc->base.bind_addr.port) == laddr->v4.sin_port) &&
1002 (htons(asoc->peer.port) == paddr->v4.sin_port) &&
1003 net_eq(sock_net(asoc->base.sk), net)) {
1004 transport = sctp_assoc_lookup_paddr(asoc, paddr);
1005 if (!transport)
1006 goto out;
1007
1008 if (sctp_bind_addr_match(&asoc->base.bind_addr, laddr,
1009 sctp_sk(asoc->base.sk)))
1010 goto out;
1011 }
1012 transport = NULL;
1013
1014 out:
1015 return transport;
1016 }
1017
1018 /* Do delayed input processing. This is scheduled by sctp_rcv(). */
1019 static void sctp_assoc_bh_rcv(struct work_struct *work)
1020 {
1021 struct sctp_association *asoc =
1022 container_of(work, struct sctp_association,
1023 base.inqueue.immediate);
1024 struct net *net = sock_net(asoc->base.sk);
1025 struct sctp_endpoint *ep;
1026 struct sctp_chunk *chunk;
1027 struct sctp_inq *inqueue;
1028 int state;
1029 sctp_subtype_t subtype;
1030 int error = 0;
1031
1032 /* The association should be held so we should be safe. */
1033 ep = asoc->ep;
1034
1035 inqueue = &asoc->base.inqueue;
1036 sctp_association_hold(asoc);
1037 while (NULL != (chunk = sctp_inq_pop(inqueue))) {
1038 state = asoc->state;
1039 subtype = SCTP_ST_CHUNK(chunk->chunk_hdr->type);
1040
1041 /* SCTP-AUTH, Section 6.3:
1042 * The receiver has a list of chunk types which it expects
1043 * to be received only after an AUTH-chunk. This list has
1044 * been sent to the peer during the association setup. It
1045 * MUST silently discard these chunks if they are not placed
1046 * after an AUTH chunk in the packet.
1047 */
1048 if (sctp_auth_recv_cid(subtype.chunk, asoc) && !chunk->auth)
1049 continue;
1050
1051 /* Remember where the last DATA chunk came from so we
1052 * know where to send the SACK.
1053 */
1054 if (sctp_chunk_is_data(chunk))
1055 asoc->peer.last_data_from = chunk->transport;
1056 else {
1057 SCTP_INC_STATS(net, SCTP_MIB_INCTRLCHUNKS);
1058 asoc->stats.ictrlchunks++;
1059 if (chunk->chunk_hdr->type == SCTP_CID_SACK)
1060 asoc->stats.isacks++;
1061 }
1062
1063 if (chunk->transport)
1064 chunk->transport->last_time_heard = ktime_get();
1065
1066 /* Run through the state machine. */
1067 error = sctp_do_sm(net, SCTP_EVENT_T_CHUNK, subtype,
1068 state, ep, asoc, chunk, GFP_ATOMIC);
1069
1070 /* Check to see if the association is freed in response to
1071 * the incoming chunk. If so, get out of the while loop.
1072 */
1073 if (asoc->base.dead)
1074 break;
1075
1076 /* If there is an error on chunk, discard this packet. */
1077 if (error && chunk)
1078 chunk->pdiscard = 1;
1079 }
1080 sctp_association_put(asoc);
1081 }
1082
1083 /* This routine moves an association from its old sk to a new sk. */
1084 void sctp_assoc_migrate(struct sctp_association *assoc, struct sock *newsk)
1085 {
1086 struct sctp_sock *newsp = sctp_sk(newsk);
1087 struct sock *oldsk = assoc->base.sk;
1088
1089 /* Delete the association from the old endpoint's list of
1090 * associations.
1091 */
1092 list_del_init(&assoc->asocs);
1093
1094 /* Decrement the backlog value for a TCP-style socket. */
1095 if (sctp_style(oldsk, TCP))
1096 oldsk->sk_ack_backlog--;
1097
1098 /* Release references to the old endpoint and the sock. */
1099 sctp_endpoint_put(assoc->ep);
1100 sock_put(assoc->base.sk);
1101
1102 /* Get a reference to the new endpoint. */
1103 assoc->ep = newsp->ep;
1104 sctp_endpoint_hold(assoc->ep);
1105
1106 /* Get a reference to the new sock. */
1107 assoc->base.sk = newsk;
1108 sock_hold(assoc->base.sk);
1109
1110 /* Add the association to the new endpoint's list of associations. */
1111 sctp_endpoint_add_asoc(newsp->ep, assoc);
1112 }
1113
1114 /* Update an association (possibly from unexpected COOKIE-ECHO processing). */
1115 int sctp_assoc_update(struct sctp_association *asoc,
1116 struct sctp_association *new)
1117 {
1118 struct sctp_transport *trans;
1119 struct list_head *pos, *temp;
1120
1121 /* Copy in new parameters of peer. */
1122 asoc->c = new->c;
1123 asoc->peer.rwnd = new->peer.rwnd;
1124 asoc->peer.sack_needed = new->peer.sack_needed;
1125 asoc->peer.auth_capable = new->peer.auth_capable;
1126 asoc->peer.i = new->peer.i;
1127
1128 if (!sctp_tsnmap_init(&asoc->peer.tsn_map, SCTP_TSN_MAP_INITIAL,
1129 asoc->peer.i.initial_tsn, GFP_ATOMIC))
1130 return -ENOMEM;
1131
1132 /* Remove any peer addresses not present in the new association. */
1133 list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
1134 trans = list_entry(pos, struct sctp_transport, transports);
1135 if (!sctp_assoc_lookup_paddr(new, &trans->ipaddr)) {
1136 sctp_assoc_rm_peer(asoc, trans);
1137 continue;
1138 }
1139
1140 if (asoc->state >= SCTP_STATE_ESTABLISHED)
1141 sctp_transport_reset(trans);
1142 }
1143
1144 /* If the case is A (association restart), use
1145 * initial_tsn as next_tsn. If the case is B, use
1146 * current next_tsn in case data sent to peer
1147 * has been discarded and needs retransmission.
1148 */
1149 if (asoc->state >= SCTP_STATE_ESTABLISHED) {
1150 asoc->next_tsn = new->next_tsn;
1151 asoc->ctsn_ack_point = new->ctsn_ack_point;
1152 asoc->adv_peer_ack_point = new->adv_peer_ack_point;
1153
1154 /* Reinitialize SSN for both local streams
1155 * and peer's streams.
1156 */
1157 sctp_stream_clear(&asoc->stream);
1158
1159 /* Flush the ULP reassembly and ordered queue.
1160 * Any data there will now be stale and will
1161 * cause problems.
1162 */
1163 sctp_ulpq_flush(&asoc->ulpq);
1164
1165 /* reset the overall association error count so
1166 * that the restarted association doesn't get torn
1167 * down on the next retransmission timer.
1168 */
1169 asoc->overall_error_count = 0;
1170
1171 } else {
1172 /* Add any peer addresses from the new association. */
1173 list_for_each_entry(trans, &new->peer.transport_addr_list,
1174 transports)
1175 if (!sctp_assoc_lookup_paddr(asoc, &trans->ipaddr) &&
1176 !sctp_assoc_add_peer(asoc, &trans->ipaddr,
1177 GFP_ATOMIC, trans->state))
1178 return -ENOMEM;
1179
1180 asoc->ctsn_ack_point = asoc->next_tsn - 1;
1181 asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
1182
1183 if (sctp_state(asoc, COOKIE_WAIT))
1184 sctp_stream_update(&asoc->stream, &new->stream);
1185
1186 /* get a new assoc id if we don't have one yet. */
1187 if (sctp_assoc_set_id(asoc, GFP_ATOMIC))
1188 return -ENOMEM;
1189 }
1190
1191 /* SCTP-AUTH: Save the peer parameters from the new associations
1192 * and also move the association shared keys over
1193 */
1194 kfree(asoc->peer.peer_random);
1195 asoc->peer.peer_random = new->peer.peer_random;
1196 new->peer.peer_random = NULL;
1197
1198 kfree(asoc->peer.peer_chunks);
1199 asoc->peer.peer_chunks = new->peer.peer_chunks;
1200 new->peer.peer_chunks = NULL;
1201
1202 kfree(asoc->peer.peer_hmacs);
1203 asoc->peer.peer_hmacs = new->peer.peer_hmacs;
1204 new->peer.peer_hmacs = NULL;
1205
1206 return sctp_auth_asoc_init_active_key(asoc, GFP_ATOMIC);
1207 }
1208
1209 /* Update the retran path for sending a retransmitted packet.
1210 * See also RFC4960, 6.4. Multi-Homed SCTP Endpoints:
1211 *
1212 * When there is outbound data to send and the primary path
1213 * becomes inactive (e.g., due to failures), or where the
1214 * SCTP user explicitly requests to send data to an
1215 * inactive destination transport address, before reporting
1216 * an error to its ULP, the SCTP endpoint should try to send
1217 * the data to an alternate active destination transport
1218 * address if one exists.
1219 *
1220 * When retransmitting data that timed out, if the endpoint
1221 * is multihomed, it should consider each source-destination
1222 * address pair in its retransmission selection policy.
1223 * When retransmitting timed-out data, the endpoint should
1224 * attempt to pick the most divergent source-destination
1225 * pair from the original source-destination pair to which
1226 * the packet was transmitted.
1227 *
1228 * Note: Rules for picking the most divergent source-destination
1229 * pair are an implementation decision and are not specified
1230 * within this document.
1231 *
1232 * Our basic strategy is to round-robin transports in priorities
1233 * according to sctp_trans_score() e.g., if no such
1234 * transport with state SCTP_ACTIVE exists, round-robin through
1235 * SCTP_UNKNOWN, etc. You get the picture.
1236 */
1237 static u8 sctp_trans_score(const struct sctp_transport *trans)
1238 {
1239 switch (trans->state) {
1240 case SCTP_ACTIVE:
1241 return 3; /* best case */
1242 case SCTP_UNKNOWN:
1243 return 2;
1244 case SCTP_PF:
1245 return 1;
1246 default: /* case SCTP_INACTIVE */
1247 return 0; /* worst case */
1248 }
1249 }
1250
1251 static struct sctp_transport *sctp_trans_elect_tie(struct sctp_transport *trans1,
1252 struct sctp_transport *trans2)
1253 {
1254 if (trans1->error_count > trans2->error_count) {
1255 return trans2;
1256 } else if (trans1->error_count == trans2->error_count &&
1257 ktime_after(trans2->last_time_heard,
1258 trans1->last_time_heard)) {
1259 return trans2;
1260 } else {
1261 return trans1;
1262 }
1263 }
1264
1265 static struct sctp_transport *sctp_trans_elect_best(struct sctp_transport *curr,
1266 struct sctp_transport *best)
1267 {
1268 u8 score_curr, score_best;
1269
1270 if (best == NULL || curr == best)
1271 return curr;
1272
1273 score_curr = sctp_trans_score(curr);
1274 score_best = sctp_trans_score(best);
1275
1276 /* First, try a score-based selection if both transport states
1277 * differ. If we're in a tie, lets try to make a more clever
1278 * decision here based on error counts and last time heard.
1279 */
1280 if (score_curr > score_best)
1281 return curr;
1282 else if (score_curr == score_best)
1283 return sctp_trans_elect_tie(best, curr);
1284 else
1285 return best;
1286 }
1287
1288 void sctp_assoc_update_retran_path(struct sctp_association *asoc)
1289 {
1290 struct sctp_transport *trans = asoc->peer.retran_path;
1291 struct sctp_transport *trans_next = NULL;
1292
1293 /* We're done as we only have the one and only path. */
1294 if (asoc->peer.transport_count == 1)
1295 return;
1296 /* If active_path and retran_path are the same and active,
1297 * then this is the only active path. Use it.
1298 */
1299 if (asoc->peer.active_path == asoc->peer.retran_path &&
1300 asoc->peer.active_path->state == SCTP_ACTIVE)
1301 return;
1302
1303 /* Iterate from retran_path's successor back to retran_path. */
1304 for (trans = list_next_entry(trans, transports); 1;
1305 trans = list_next_entry(trans, transports)) {
1306 /* Manually skip the head element. */
1307 if (&trans->transports == &asoc->peer.transport_addr_list)
1308 continue;
1309 if (trans->state == SCTP_UNCONFIRMED)
1310 continue;
1311 trans_next = sctp_trans_elect_best(trans, trans_next);
1312 /* Active is good enough for immediate return. */
1313 if (trans_next->state == SCTP_ACTIVE)
1314 break;
1315 /* We've reached the end, time to update path. */
1316 if (trans == asoc->peer.retran_path)
1317 break;
1318 }
1319
1320 asoc->peer.retran_path = trans_next;
1321
1322 pr_debug("%s: association:%p updated new path to addr:%pISpc\n",
1323 __func__, asoc, &asoc->peer.retran_path->ipaddr.sa);
1324 }
1325
1326 static void sctp_select_active_and_retran_path(struct sctp_association *asoc)
1327 {
1328 struct sctp_transport *trans, *trans_pri = NULL, *trans_sec = NULL;
1329 struct sctp_transport *trans_pf = NULL;
1330
1331 /* Look for the two most recently used active transports. */
1332 list_for_each_entry(trans, &asoc->peer.transport_addr_list,
1333 transports) {
1334 /* Skip uninteresting transports. */
1335 if (trans->state == SCTP_INACTIVE ||
1336 trans->state == SCTP_UNCONFIRMED)
1337 continue;
1338 /* Keep track of the best PF transport from our
1339 * list in case we don't find an active one.
1340 */
1341 if (trans->state == SCTP_PF) {
1342 trans_pf = sctp_trans_elect_best(trans, trans_pf);
1343 continue;
1344 }
1345 /* For active transports, pick the most recent ones. */
1346 if (trans_pri == NULL ||
1347 ktime_after(trans->last_time_heard,
1348 trans_pri->last_time_heard)) {
1349 trans_sec = trans_pri;
1350 trans_pri = trans;
1351 } else if (trans_sec == NULL ||
1352 ktime_after(trans->last_time_heard,
1353 trans_sec->last_time_heard)) {
1354 trans_sec = trans;
1355 }
1356 }
1357
1358 /* RFC 2960 6.4 Multi-Homed SCTP Endpoints
1359 *
1360 * By default, an endpoint should always transmit to the primary
1361 * path, unless the SCTP user explicitly specifies the
1362 * destination transport address (and possibly source transport
1363 * address) to use. [If the primary is active but not most recent,
1364 * bump the most recently used transport.]
1365 */
1366 if ((asoc->peer.primary_path->state == SCTP_ACTIVE ||
1367 asoc->peer.primary_path->state == SCTP_UNKNOWN) &&
1368 asoc->peer.primary_path != trans_pri) {
1369 trans_sec = trans_pri;
1370 trans_pri = asoc->peer.primary_path;
1371 }
1372
1373 /* We did not find anything useful for a possible retransmission
1374 * path; either primary path that we found is the the same as
1375 * the current one, or we didn't generally find an active one.
1376 */
1377 if (trans_sec == NULL)
1378 trans_sec = trans_pri;
1379
1380 /* If we failed to find a usable transport, just camp on the
1381 * active or pick a PF iff it's the better choice.
1382 */
1383 if (trans_pri == NULL) {
1384 trans_pri = sctp_trans_elect_best(asoc->peer.active_path, trans_pf);
1385 trans_sec = trans_pri;
1386 }
1387
1388 /* Set the active and retran transports. */
1389 asoc->peer.active_path = trans_pri;
1390 asoc->peer.retran_path = trans_sec;
1391 }
1392
1393 struct sctp_transport *
1394 sctp_assoc_choose_alter_transport(struct sctp_association *asoc,
1395 struct sctp_transport *last_sent_to)
1396 {
1397 /* If this is the first time packet is sent, use the active path,
1398 * else use the retran path. If the last packet was sent over the
1399 * retran path, update the retran path and use it.
1400 */
1401 if (last_sent_to == NULL) {
1402 return asoc->peer.active_path;
1403 } else {
1404 if (last_sent_to == asoc->peer.retran_path)
1405 sctp_assoc_update_retran_path(asoc);
1406
1407 return asoc->peer.retran_path;
1408 }
1409 }
1410
1411 /* Update the association's pmtu and frag_point by going through all the
1412 * transports. This routine is called when a transport's PMTU has changed.
1413 */
1414 void sctp_assoc_sync_pmtu(struct sctp_association *asoc)
1415 {
1416 struct sctp_transport *t;
1417 __u32 pmtu = 0;
1418
1419 if (!asoc)
1420 return;
1421
1422 /* Get the lowest pmtu of all the transports. */
1423 list_for_each_entry(t, &asoc->peer.transport_addr_list,
1424 transports) {
1425 if (t->pmtu_pending && t->dst) {
1426 sctp_transport_update_pmtu(
1427 t, SCTP_TRUNC4(dst_mtu(t->dst)));
1428 t->pmtu_pending = 0;
1429 }
1430 if (!pmtu || (t->pathmtu < pmtu))
1431 pmtu = t->pathmtu;
1432 }
1433
1434 if (pmtu) {
1435 asoc->pathmtu = pmtu;
1436 asoc->frag_point = sctp_frag_point(asoc, pmtu);
1437 }
1438
1439 pr_debug("%s: asoc:%p, pmtu:%d, frag_point:%d\n", __func__, asoc,
1440 asoc->pathmtu, asoc->frag_point);
1441 }
1442
1443 /* Should we send a SACK to update our peer? */
1444 static inline bool sctp_peer_needs_update(struct sctp_association *asoc)
1445 {
1446 struct net *net = sock_net(asoc->base.sk);
1447 switch (asoc->state) {
1448 case SCTP_STATE_ESTABLISHED:
1449 case SCTP_STATE_SHUTDOWN_PENDING:
1450 case SCTP_STATE_SHUTDOWN_RECEIVED:
1451 case SCTP_STATE_SHUTDOWN_SENT:
1452 if ((asoc->rwnd > asoc->a_rwnd) &&
1453 ((asoc->rwnd - asoc->a_rwnd) >= max_t(__u32,
1454 (asoc->base.sk->sk_rcvbuf >> net->sctp.rwnd_upd_shift),
1455 asoc->pathmtu)))
1456 return true;
1457 break;
1458 default:
1459 break;
1460 }
1461 return false;
1462 }
1463
1464 /* Increase asoc's rwnd by len and send any window update SACK if needed. */
1465 void sctp_assoc_rwnd_increase(struct sctp_association *asoc, unsigned int len)
1466 {
1467 struct sctp_chunk *sack;
1468 struct timer_list *timer;
1469
1470 if (asoc->rwnd_over) {
1471 if (asoc->rwnd_over >= len) {
1472 asoc->rwnd_over -= len;
1473 } else {
1474 asoc->rwnd += (len - asoc->rwnd_over);
1475 asoc->rwnd_over = 0;
1476 }
1477 } else {
1478 asoc->rwnd += len;
1479 }
1480
1481 /* If we had window pressure, start recovering it
1482 * once our rwnd had reached the accumulated pressure
1483 * threshold. The idea is to recover slowly, but up
1484 * to the initial advertised window.
1485 */
1486 if (asoc->rwnd_press) {
1487 int change = min(asoc->pathmtu, asoc->rwnd_press);
1488 asoc->rwnd += change;
1489 asoc->rwnd_press -= change;
1490 }
1491
1492 pr_debug("%s: asoc:%p rwnd increased by %d to (%u, %u) - %u\n",
1493 __func__, asoc, len, asoc->rwnd, asoc->rwnd_over,
1494 asoc->a_rwnd);
1495
1496 /* Send a window update SACK if the rwnd has increased by at least the
1497 * minimum of the association's PMTU and half of the receive buffer.
1498 * The algorithm used is similar to the one described in
1499 * Section 4.2.3.3 of RFC 1122.
1500 */
1501 if (sctp_peer_needs_update(asoc)) {
1502 asoc->a_rwnd = asoc->rwnd;
1503
1504 pr_debug("%s: sending window update SACK- asoc:%p rwnd:%u "
1505 "a_rwnd:%u\n", __func__, asoc, asoc->rwnd,
1506 asoc->a_rwnd);
1507
1508 sack = sctp_make_sack(asoc);
1509 if (!sack)
1510 return;
1511
1512 asoc->peer.sack_needed = 0;
1513
1514 sctp_outq_tail(&asoc->outqueue, sack, GFP_ATOMIC);
1515
1516 /* Stop the SACK timer. */
1517 timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK];
1518 if (del_timer(timer))
1519 sctp_association_put(asoc);
1520 }
1521 }
1522
1523 /* Decrease asoc's rwnd by len. */
1524 void sctp_assoc_rwnd_decrease(struct sctp_association *asoc, unsigned int len)
1525 {
1526 int rx_count;
1527 int over = 0;
1528
1529 if (unlikely(!asoc->rwnd || asoc->rwnd_over))
1530 pr_debug("%s: association:%p has asoc->rwnd:%u, "
1531 "asoc->rwnd_over:%u!\n", __func__, asoc,
1532 asoc->rwnd, asoc->rwnd_over);
1533
1534 if (asoc->ep->rcvbuf_policy)
1535 rx_count = atomic_read(&asoc->rmem_alloc);
1536 else
1537 rx_count = atomic_read(&asoc->base.sk->sk_rmem_alloc);
1538
1539 /* If we've reached or overflowed our receive buffer, announce
1540 * a 0 rwnd if rwnd would still be positive. Store the
1541 * the potential pressure overflow so that the window can be restored
1542 * back to original value.
1543 */
1544 if (rx_count >= asoc->base.sk->sk_rcvbuf)
1545 over = 1;
1546
1547 if (asoc->rwnd >= len) {
1548 asoc->rwnd -= len;
1549 if (over) {
1550 asoc->rwnd_press += asoc->rwnd;
1551 asoc->rwnd = 0;
1552 }
1553 } else {
1554 asoc->rwnd_over += len - asoc->rwnd;
1555 asoc->rwnd = 0;
1556 }
1557
1558 pr_debug("%s: asoc:%p rwnd decreased by %d to (%u, %u, %u)\n",
1559 __func__, asoc, len, asoc->rwnd, asoc->rwnd_over,
1560 asoc->rwnd_press);
1561 }
1562
1563 /* Build the bind address list for the association based on info from the
1564 * local endpoint and the remote peer.
1565 */
1566 int sctp_assoc_set_bind_addr_from_ep(struct sctp_association *asoc,
1567 sctp_scope_t scope, gfp_t gfp)
1568 {
1569 int flags;
1570
1571 /* Use scoping rules to determine the subset of addresses from
1572 * the endpoint.
1573 */
1574 flags = (PF_INET6 == asoc->base.sk->sk_family) ? SCTP_ADDR6_ALLOWED : 0;
1575 if (asoc->peer.ipv4_address)
1576 flags |= SCTP_ADDR4_PEERSUPP;
1577 if (asoc->peer.ipv6_address)
1578 flags |= SCTP_ADDR6_PEERSUPP;
1579
1580 return sctp_bind_addr_copy(sock_net(asoc->base.sk),
1581 &asoc->base.bind_addr,
1582 &asoc->ep->base.bind_addr,
1583 scope, gfp, flags);
1584 }
1585
1586 /* Build the association's bind address list from the cookie. */
1587 int sctp_assoc_set_bind_addr_from_cookie(struct sctp_association *asoc,
1588 struct sctp_cookie *cookie,
1589 gfp_t gfp)
1590 {
1591 int var_size2 = ntohs(cookie->peer_init->chunk_hdr.length);
1592 int var_size3 = cookie->raw_addr_list_len;
1593 __u8 *raw = (__u8 *)cookie->peer_init + var_size2;
1594
1595 return sctp_raw_to_bind_addrs(&asoc->base.bind_addr, raw, var_size3,
1596 asoc->ep->base.bind_addr.port, gfp);
1597 }
1598
1599 /* Lookup laddr in the bind address list of an association. */
1600 int sctp_assoc_lookup_laddr(struct sctp_association *asoc,
1601 const union sctp_addr *laddr)
1602 {
1603 int found = 0;
1604
1605 if ((asoc->base.bind_addr.port == ntohs(laddr->v4.sin_port)) &&
1606 sctp_bind_addr_match(&asoc->base.bind_addr, laddr,
1607 sctp_sk(asoc->base.sk)))
1608 found = 1;
1609
1610 return found;
1611 }
1612
1613 /* Set an association id for a given association */
1614 int sctp_assoc_set_id(struct sctp_association *asoc, gfp_t gfp)
1615 {
1616 bool preload = gfpflags_allow_blocking(gfp);
1617 int ret;
1618
1619 /* If the id is already assigned, keep it. */
1620 if (asoc->assoc_id)
1621 return 0;
1622
1623 if (preload)
1624 idr_preload(gfp);
1625 spin_lock_bh(&sctp_assocs_id_lock);
1626 /* 0 is not a valid assoc_id, must be >= 1 */
1627 ret = idr_alloc_cyclic(&sctp_assocs_id, asoc, 1, 0, GFP_NOWAIT);
1628 spin_unlock_bh(&sctp_assocs_id_lock);
1629 if (preload)
1630 idr_preload_end();
1631 if (ret < 0)
1632 return ret;
1633
1634 asoc->assoc_id = (sctp_assoc_t)ret;
1635 return 0;
1636 }
1637
1638 /* Free the ASCONF queue */
1639 static void sctp_assoc_free_asconf_queue(struct sctp_association *asoc)
1640 {
1641 struct sctp_chunk *asconf;
1642 struct sctp_chunk *tmp;
1643
1644 list_for_each_entry_safe(asconf, tmp, &asoc->addip_chunk_list, list) {
1645 list_del_init(&asconf->list);
1646 sctp_chunk_free(asconf);
1647 }
1648 }
1649
1650 /* Free asconf_ack cache */
1651 static void sctp_assoc_free_asconf_acks(struct sctp_association *asoc)
1652 {
1653 struct sctp_chunk *ack;
1654 struct sctp_chunk *tmp;
1655
1656 list_for_each_entry_safe(ack, tmp, &asoc->asconf_ack_list,
1657 transmitted_list) {
1658 list_del_init(&ack->transmitted_list);
1659 sctp_chunk_free(ack);
1660 }
1661 }
1662
1663 /* Clean up the ASCONF_ACK queue */
1664 void sctp_assoc_clean_asconf_ack_cache(const struct sctp_association *asoc)
1665 {
1666 struct sctp_chunk *ack;
1667 struct sctp_chunk *tmp;
1668
1669 /* We can remove all the entries from the queue up to
1670 * the "Peer-Sequence-Number".
1671 */
1672 list_for_each_entry_safe(ack, tmp, &asoc->asconf_ack_list,
1673 transmitted_list) {
1674 if (ack->subh.addip_hdr->serial ==
1675 htonl(asoc->peer.addip_serial))
1676 break;
1677
1678 list_del_init(&ack->transmitted_list);
1679 sctp_chunk_free(ack);
1680 }
1681 }
1682
1683 /* Find the ASCONF_ACK whose serial number matches ASCONF */
1684 struct sctp_chunk *sctp_assoc_lookup_asconf_ack(
1685 const struct sctp_association *asoc,
1686 __be32 serial)
1687 {
1688 struct sctp_chunk *ack;
1689
1690 /* Walk through the list of cached ASCONF-ACKs and find the
1691 * ack chunk whose serial number matches that of the request.
1692 */
1693 list_for_each_entry(ack, &asoc->asconf_ack_list, transmitted_list) {
1694 if (sctp_chunk_pending(ack))
1695 continue;
1696 if (ack->subh.addip_hdr->serial == serial) {
1697 sctp_chunk_hold(ack);
1698 return ack;
1699 }
1700 }
1701
1702 return NULL;
1703 }
1704
1705 void sctp_asconf_queue_teardown(struct sctp_association *asoc)
1706 {
1707 /* Free any cached ASCONF_ACK chunk. */
1708 sctp_assoc_free_asconf_acks(asoc);
1709
1710 /* Free the ASCONF queue. */
1711 sctp_assoc_free_asconf_queue(asoc);
1712
1713 /* Free any cached ASCONF chunk. */
1714 if (asoc->addip_last_asconf)
1715 sctp_chunk_free(asoc->addip_last_asconf);
1716 }