1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* SCTP kernel implementation
3 * (C) Copyright IBM Corp. 2001, 2004
4 * Copyright (c) 1999-2000 Cisco, Inc.
5 * Copyright (c) 1999-2001 Motorola, Inc.
6 * Copyright (c) 2001 Intel Corp.
7 * Copyright (c) 2001 La Monte H.P. Yarroll
8 *
9 * This file is part of the SCTP kernel implementation
10 *
11 * This module provides the abstraction for an SCTP association.
12 *
13 * Please send any bug reports or fixes you make to the
14 * email address(es):
15 * lksctp developers <linux-sctp@vger.kernel.org>
16 *
17 * Written or modified by:
18 * La Monte H.P. Yarroll <piggy@acm.org>
19 * Karl Knutson <karl@athena.chicago.il.us>
20 * Jon Grimm <jgrimm@us.ibm.com>
21 * Xingang Guo <xingang.guo@intel.com>
22 * Hui Huang <hui.huang@nokia.com>
23 * Sridhar Samudrala <sri@us.ibm.com>
24 * Daisy Chang <daisyc@us.ibm.com>
25 * Ryan Layer <rmlayer@us.ibm.com>
26 * Kevin Gao <kevin.gao@intel.com>
27 */
28
29 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
30
31 #include <linux/types.h>
32 #include <linux/fcntl.h>
33 #include <linux/poll.h>
34 #include <linux/init.h>
35
36 #include <linux/slab.h>
37 #include <linux/in.h>
38 #include <net/ipv6.h>
39 #include <net/sctp/sctp.h>
40 #include <net/sctp/sm.h>
41
42 /* Forward declarations for internal functions. */
43 static void sctp_select_active_and_retran_path(struct sctp_association *asoc);
44 static void sctp_assoc_bh_rcv(struct work_struct *work);
45 static void sctp_assoc_free_asconf_acks(struct sctp_association *asoc);
46 static void sctp_assoc_free_asconf_queue(struct sctp_association *asoc);
47
48 /* 1st Level Abstractions. */
49
50 /* Initialize a new association from provided memory. */
51 static struct sctp_association *sctp_association_init(
52 struct sctp_association *asoc,
53 const struct sctp_endpoint *ep,
54 const struct sock *sk,
55 enum sctp_scope scope, gfp_t gfp)
56 {
57 struct sctp_sock *sp;
58 struct sctp_paramhdr *p;
59 int i;
60
61 /* Retrieve the SCTP per socket area. */
62 sp = sctp_sk((struct sock *)sk);
63
64 /* Discarding const is appropriate here. */
65 asoc->ep = (struct sctp_endpoint *)ep;
66 asoc->base.sk = (struct sock *)sk;
67 asoc->base.net = sock_net(sk);
68
69 sctp_endpoint_hold(asoc->ep);
70 sock_hold(asoc->base.sk);
71
72 /* Initialize the common base substructure. */
73 asoc->base.type = SCTP_EP_TYPE_ASSOCIATION;
74
75 /* Initialize the object handling fields. */
76 refcount_set(&asoc->base.refcnt, 1);
77
78 /* Initialize the bind addr area. */
79 sctp_bind_addr_init(&asoc->base.bind_addr, ep->base.bind_addr.port);
80
81 asoc->state = SCTP_STATE_CLOSED;
82 asoc->cookie_life = ms_to_ktime(sp->assocparams.sasoc_cookie_life);
83 asoc->user_frag = sp->user_frag;
84
85 /* Set the association max_retrans and RTO values from the
86 * socket values.
87 */
88 asoc->max_retrans = sp->assocparams.sasoc_asocmaxrxt;
89 asoc->pf_retrans = sp->pf_retrans;
90 asoc->ps_retrans = sp->ps_retrans;
91 asoc->pf_expose = sp->pf_expose;
92
93 asoc->rto_initial = msecs_to_jiffies(sp->rtoinfo.srto_initial);
94 asoc->rto_max = msecs_to_jiffies(sp->rtoinfo.srto_max);
95 asoc->rto_min = msecs_to_jiffies(sp->rtoinfo.srto_min);
96
97 /* Initialize the association's heartbeat interval based on the
98 * sock configured value.
99 */
100 asoc->hbinterval = msecs_to_jiffies(sp->hbinterval);
101 asoc->probe_interval = msecs_to_jiffies(sp->probe_interval);
102
103 asoc->encap_port = sp->encap_port;
104
105 /* Initialize path max retrans value. */
106 asoc->pathmaxrxt = sp->pathmaxrxt;
107
108 asoc->flowlabel = sp->flowlabel;
109 asoc->dscp = sp->dscp;
110
111 /* Set association default SACK delay */
112 asoc->sackdelay = msecs_to_jiffies(sp->sackdelay);
113 asoc->sackfreq = sp->sackfreq;
114
115 /* Set the association default flags controlling
116 * Heartbeat, SACK delay, and Path MTU Discovery.
117 */
118 asoc->param_flags = sp->param_flags;
119
120 /* Initialize the maximum number of new data packets that can be sent
121 * in a burst.
122 */
123 asoc->max_burst = sp->max_burst;
124
125 asoc->subscribe = sp->subscribe;
126
127 /* initialize association timers */
128 asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_COOKIE] = asoc->rto_initial;
129 asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_INIT] = asoc->rto_initial;
130 asoc->timeouts[SCTP_EVENT_TIMEOUT_T2_SHUTDOWN] = asoc->rto_initial;
131
132 /* sctpimpguide Section 2.12.2
133 * If the 'T5-shutdown-guard' timer is used, it SHOULD be set to the
134 * recommended value of 5 times 'RTO.Max'.
135 */
136 asoc->timeouts[SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]
137 = 5 * asoc->rto_max;
138
139 asoc->timeouts[SCTP_EVENT_TIMEOUT_SACK] = asoc->sackdelay;
140 asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE] = sp->autoclose * HZ;
141
142 /* Initializes the timers */
143 for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i)
144 timer_setup(&asoc->timers[i], sctp_timer_events[i], 0);
145
146 /* Pull default initialization values from the sock options.
147 * Note: This assumes that the values have already been
148 * validated in the sock.
149 */
150 asoc->c.sinit_max_instreams = sp->initmsg.sinit_max_instreams;
151 asoc->c.sinit_num_ostreams = sp->initmsg.sinit_num_ostreams;
152 asoc->max_init_attempts = sp->initmsg.sinit_max_attempts;
153
154 asoc->max_init_timeo =
155 msecs_to_jiffies(sp->initmsg.sinit_max_init_timeo);
156
157 /* Set the local window size for receive.
158 * This is also the rcvbuf space per association.
159 * RFC 6 - A SCTP receiver MUST be able to receive a minimum of
160 * 1500 bytes in one SCTP packet.
161 */
162 if ((sk->sk_rcvbuf/2) < SCTP_DEFAULT_MINWINDOW)
163 asoc->rwnd = SCTP_DEFAULT_MINWINDOW;
164 else
165 asoc->rwnd = sk->sk_rcvbuf/2;
166
167 asoc->a_rwnd = asoc->rwnd;
168
169 /* Use my own max window until I learn something better. */
170 asoc->peer.rwnd = SCTP_DEFAULT_MAXWINDOW;
171
172 /* Initialize the receive memory counter */
173 atomic_set(&asoc->rmem_alloc, 0);
174
175 init_waitqueue_head(&asoc->wait);
176
177 asoc->c.my_vtag = sctp_generate_tag(ep);
178 asoc->c.my_port = ep->base.bind_addr.port;
179
180 asoc->c.initial_tsn = sctp_generate_tsn(ep);
181
182 asoc->next_tsn = asoc->c.initial_tsn;
183
184 asoc->ctsn_ack_point = asoc->next_tsn - 1;
185 asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
186 asoc->highest_sacked = asoc->ctsn_ack_point;
187 asoc->last_cwr_tsn = asoc->ctsn_ack_point;
188
189 /* ADDIP Section 4.1 Asconf Chunk Procedures
190 *
191 * When an endpoint has an ASCONF signaled change to be sent to the
192 * remote endpoint it should do the following:
193 * ...
194 * A2) a serial number should be assigned to the chunk. The serial
195 * number SHOULD be a monotonically increasing number. The serial
196 * numbers SHOULD be initialized at the start of the
197 * association to the same value as the initial TSN.
198 */
199 asoc->addip_serial = asoc->c.initial_tsn;
200 asoc->strreset_outseq = asoc->c.initial_tsn;
201
202 INIT_LIST_HEAD(&asoc->addip_chunk_list);
203 INIT_LIST_HEAD(&asoc->asconf_ack_list);
204
205 /* Make an empty list of remote transport addresses. */
206 INIT_LIST_HEAD(&asoc->peer.transport_addr_list);
207
208 /* RFC 2960 5.1 Normal Establishment of an Association
209 *
210 * After the reception of the first data chunk in an
211 * association the endpoint must immediately respond with a
212 * sack to acknowledge the data chunk. Subsequent
213 * acknowledgements should be done as described in Section
214 * 6.2.
215 *
216 * [We implement this by telling a new association that it
217 * already received one packet.]
218 */
219 asoc->peer.sack_needed = 1;
220 asoc->peer.sack_generation = 1;
221
222 /* Create an input queue. */
223 sctp_inq_init(&asoc->base.inqueue);
224 sctp_inq_set_th_handler(&asoc->base.inqueue, sctp_assoc_bh_rcv);
225
226 /* Create an output queue. */
227 sctp_outq_init(asoc, &asoc->outqueue);
228
229 sctp_ulpq_init(&asoc->ulpq, asoc);
230
231 if (sctp_stream_init(&asoc->stream, asoc->c.sinit_num_ostreams, 0, gfp))
232 goto stream_free;
233
234 /* Initialize default path MTU. */
235 asoc->pathmtu = sp->pathmtu;
236 sctp_assoc_update_frag_point(asoc);
237
238 /* Assume that peer would support both address types unless we are
239 * told otherwise.
240 */
241 asoc->peer.ipv4_address = 1;
242 if (asoc->base.sk->sk_family == PF_INET6)
243 asoc->peer.ipv6_address = 1;
244 INIT_LIST_HEAD(&asoc->asocs);
245
246 asoc->default_stream = sp->default_stream;
247 asoc->default_ppid = sp->default_ppid;
248 asoc->default_flags = sp->default_flags;
249 asoc->default_context = sp->default_context;
250 asoc->default_timetolive = sp->default_timetolive;
251 asoc->default_rcv_context = sp->default_rcv_context;
252
253 /* AUTH related initializations */
254 INIT_LIST_HEAD(&asoc->endpoint_shared_keys);
255 if (sctp_auth_asoc_copy_shkeys(ep, asoc, gfp))
256 goto stream_free;
257
258 asoc->active_key_id = ep->active_key_id;
259 asoc->strreset_enable = ep->strreset_enable;
260
261 /* Save the hmacs and chunks list into this association */
262 if (ep->auth_hmacs_list)
263 memcpy(asoc->c.auth_hmacs, ep->auth_hmacs_list,
264 ntohs(ep->auth_hmacs_list->param_hdr.length));
265 if (ep->auth_chunk_list)
266 memcpy(asoc->c.auth_chunks, ep->auth_chunk_list,
267 ntohs(ep->auth_chunk_list->param_hdr.length));
268
269 /* Get the AUTH random number for this association */
270 p = (struct sctp_paramhdr *)asoc->c.auth_random;
271 p->type = SCTP_PARAM_RANDOM;
272 p->length = htons(sizeof(*p) + SCTP_AUTH_RANDOM_LENGTH);
273 get_random_bytes(p+1, SCTP_AUTH_RANDOM_LENGTH);
274
275 return asoc;
276
277 stream_free:
278 sctp_stream_free(&asoc->stream);
279 sock_put(asoc->base.sk);
280 sctp_endpoint_put(asoc->ep);
281 return NULL;
282 }
283
284 /* Allocate and initialize a new association */
285 struct sctp_association *sctp_association_new(const struct sctp_endpoint *ep,
286 const struct sock *sk,
287 enum sctp_scope scope, gfp_t gfp)
288 {
289 struct sctp_association *asoc;
290
291 asoc = kzalloc(sizeof(*asoc), gfp);
292 if (!asoc)
293 goto fail;
294
295 if (!sctp_association_init(asoc, ep, sk, scope, gfp))
296 goto fail_init;
297
298 SCTP_DBG_OBJCNT_INC(assoc);
299
300 pr_debug("Created asoc %p\n", asoc);
301
302 return asoc;
303
304 fail_init:
305 kfree(asoc);
306 fail:
307 return NULL;
308 }
309
310 /* Free this association if possible. There may still be users, so
311 * the actual deallocation may be delayed.
312 */
313 void sctp_association_free(struct sctp_association *asoc)
314 {
315 struct sock *sk = asoc->base.sk;
316 struct sctp_transport *transport;
317 struct list_head *pos, *temp;
318 int i;
319
320 /* Only real associations count against the endpoint, so
321 * don't bother for if this is a temporary association.
322 */
323 if (!list_empty(&asoc->asocs)) {
324 list_del(&asoc->asocs);
325
326 /* Decrement the backlog value for a TCP-style listening
327 * socket.
328 */
329 if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
330 sk_acceptq_removed(sk);
331 }
332
333 /* Mark as dead, so other users can know this structure is
334 * going away.
335 */
336 asoc->base.dead = true;
337
338 /* Dispose of any data lying around in the outqueue. */
339 sctp_outq_free(&asoc->outqueue);
340
341 /* Dispose of any pending messages for the upper layer. */
342 sctp_ulpq_free(&asoc->ulpq);
343
344 /* Dispose of any pending chunks on the inqueue. */
345 sctp_inq_free(&asoc->base.inqueue);
346
347 sctp_tsnmap_free(&asoc->peer.tsn_map);
348
349 /* Free stream information. */
350 sctp_stream_free(&asoc->stream);
351
352 if (asoc->strreset_chunk)
353 sctp_chunk_free(asoc->strreset_chunk);
354
355 /* Clean up the bound address list. */
356 sctp_bind_addr_free(&asoc->base.bind_addr);
357
358 /* Do we need to go through all of our timers and
359 * delete them? To be safe we will try to delete all, but we
360 * should be able to go through and make a guess based
361 * on our state.
362 */
363 for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i) {
364 if (del_timer(&asoc->timers[i]))
365 sctp_association_put(asoc);
366 }
367
368 /* Free peer's cached cookie. */
369 kfree(asoc->peer.cookie);
370 kfree(asoc->peer.peer_random);
371 kfree(asoc->peer.peer_chunks);
372 kfree(asoc->peer.peer_hmacs);
373
374 /* Release the transport structures. */
375 list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
376 transport = list_entry(pos, struct sctp_transport, transports);
377 list_del_rcu(pos);
378 sctp_unhash_transport(transport);
379 sctp_transport_free(transport);
380 }
381
382 asoc->peer.transport_count = 0;
383
384 sctp_asconf_queue_teardown(asoc);
385
386 /* Free pending address space being deleted */
387 kfree(asoc->asconf_addr_del_pending);
388
389 /* AUTH - Free the endpoint shared keys */
390 sctp_auth_destroy_keys(&asoc->endpoint_shared_keys);
391
392 /* AUTH - Free the association shared key */
393 sctp_auth_key_put(asoc->asoc_shared_key);
394
395 sctp_association_put(asoc);
396 }
397
398 /* Cleanup and free up an association. */
399 static void sctp_association_destroy(struct sctp_association *asoc)
400 {
401 if (unlikely(!asoc->base.dead)) {
402 WARN(1, "Attempt to destroy undead association %p!\n", asoc);
403 return;
404 }
405
406 sctp_endpoint_put(asoc->ep);
407 sock_put(asoc->base.sk);
408
409 if (asoc->assoc_id != 0) {
410 spin_lock_bh(&sctp_assocs_id_lock);
411 idr_remove(&sctp_assocs_id, asoc->assoc_id);
412 spin_unlock_bh(&sctp_assocs_id_lock);
413 }
414
415 WARN_ON(atomic_read(&asoc->rmem_alloc));
416
417 kfree_rcu(asoc, rcu);
418 SCTP_DBG_OBJCNT_DEC(assoc);
419 }
420
421 /* Change the primary destination address for the peer. */
422 void sctp_assoc_set_primary(struct sctp_association *asoc,
423 struct sctp_transport *transport)
424 {
425 int changeover = 0;
426
427 /* it's a changeover only if we already have a primary path
428 * that we are changing
429 */
430 if (asoc->peer.primary_path != NULL &&
431 asoc->peer.primary_path != transport)
432 changeover = 1 ;
433
434 asoc->peer.primary_path = transport;
435 sctp_ulpevent_notify_peer_addr_change(transport,
436 SCTP_ADDR_MADE_PRIM, 0);
437
438 /* Set a default msg_name for events. */
439 memcpy(&asoc->peer.primary_addr, &transport->ipaddr,
440 sizeof(union sctp_addr));
441
442 /* If the primary path is changing, assume that the
443 * user wants to use this new path.
444 */
445 if ((transport->state == SCTP_ACTIVE) ||
446 (transport->state == SCTP_UNKNOWN))
447 asoc->peer.active_path = transport;
448
449 /*
450 * SFR-CACC algorithm:
451 * Upon the receipt of a request to change the primary
452 * destination address, on the data structure for the new
453 * primary destination, the sender MUST do the following:
454 *
455 * 1) If CHANGEOVER_ACTIVE is set, then there was a switch
456 * to this destination address earlier. The sender MUST set
457 * CYCLING_CHANGEOVER to indicate that this switch is a
458 * double switch to the same destination address.
459 *
460 * Really, only bother is we have data queued or outstanding on
461 * the association.
462 */
463 if (!asoc->outqueue.outstanding_bytes && !asoc->outqueue.out_qlen)
464 return;
465
466 if (transport->cacc.changeover_active)
467 transport->cacc.cycling_changeover = changeover;
468
469 /* 2) The sender MUST set CHANGEOVER_ACTIVE to indicate that
470 * a changeover has occurred.
471 */
472 transport->cacc.changeover_active = changeover;
473
474 /* 3) The sender MUST store the next TSN to be sent in
475 * next_tsn_at_change.
476 */
477 transport->cacc.next_tsn_at_change = asoc->next_tsn;
478 }
479
480 /* Remove a transport from an association. */
481 void sctp_assoc_rm_peer(struct sctp_association *asoc,
482 struct sctp_transport *peer)
483 {
484 struct sctp_transport *transport;
485 struct list_head *pos;
486 struct sctp_chunk *ch;
487
488 pr_debug("%s: association:%p addr:%pISpc\n",
489 __func__, asoc, &peer->ipaddr.sa);
490
491 /* If we are to remove the current retran_path, update it
492 * to the next peer before removing this peer from the list.
493 */
494 if (asoc->peer.retran_path == peer)
495 sctp_assoc_update_retran_path(asoc);
496
497 /* Remove this peer from the list. */
498 list_del_rcu(&peer->transports);
499 /* Remove this peer from the transport hashtable */
500 sctp_unhash_transport(peer);
501
502 /* Get the first transport of asoc. */
503 pos = asoc->peer.transport_addr_list.next;
504 transport = list_entry(pos, struct sctp_transport, transports);
505
506 /* Update any entries that match the peer to be deleted. */
507 if (asoc->peer.primary_path == peer)
508 sctp_assoc_set_primary(asoc, transport);
509 if (asoc->peer.active_path == peer)
510 asoc->peer.active_path = transport;
511 if (asoc->peer.retran_path == peer)
512 asoc->peer.retran_path = transport;
513 if (asoc->peer.last_data_from == peer)
514 asoc->peer.last_data_from = transport;
515
516 if (asoc->strreset_chunk &&
517 asoc->strreset_chunk->transport == peer) {
518 asoc->strreset_chunk->transport = transport;
519 sctp_transport_reset_reconf_timer(transport);
520 }
521
522 /* If we remove the transport an INIT was last sent to, set it to
523 * NULL. Combined with the update of the retran path above, this
524 * will cause the next INIT to be sent to the next available
525 * transport, maintaining the cycle.
526 */
527 if (asoc->init_last_sent_to == peer)
528 asoc->init_last_sent_to = NULL;
529
530 /* If we remove the transport an SHUTDOWN was last sent to, set it
531 * to NULL. Combined with the update of the retran path above, this
532 * will cause the next SHUTDOWN to be sent to the next available
533 * transport, maintaining the cycle.
534 */
535 if (asoc->shutdown_last_sent_to == peer)
536 asoc->shutdown_last_sent_to = NULL;
537
538 /* If we remove the transport an ASCONF was last sent to, set it to
539 * NULL.
540 */
541 if (asoc->addip_last_asconf &&
542 asoc->addip_last_asconf->transport == peer)
543 asoc->addip_last_asconf->transport = NULL;
544
545 /* If we have something on the transmitted list, we have to
546 * save it off. The best place is the active path.
547 */
548 if (!list_empty(&peer->transmitted)) {
549 struct sctp_transport *active = asoc->peer.active_path;
550
551 /* Reset the transport of each chunk on this list */
552 list_for_each_entry(ch, &peer->transmitted,
553 transmitted_list) {
554 ch->transport = NULL;
555 ch->rtt_in_progress = 0;
556 }
557
558 list_splice_tail_init(&peer->transmitted,
559 &active->transmitted);
560
561 /* Start a T3 timer here in case it wasn't running so
562 * that these migrated packets have a chance to get
563 * retransmitted.
564 */
565 if (!timer_pending(&active->T3_rtx_timer))
566 if (!mod_timer(&active->T3_rtx_timer,
567 jiffies + active->rto))
568 sctp_transport_hold(active);
569 }
570
571 list_for_each_entry(ch, &asoc->outqueue.out_chunk_list, list)
572 if (ch->transport == peer)
573 ch->transport = NULL;
574
575 asoc->peer.transport_count--;
576
577 sctp_ulpevent_notify_peer_addr_change(peer, SCTP_ADDR_REMOVED, 0);
578 sctp_transport_free(peer);
579 }
580
581 /* Add a transport address to an association. */
582 struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc,
583 const union sctp_addr *addr,
584 const gfp_t gfp,
585 const int peer_state)
586 {
587 struct sctp_transport *peer;
588 struct sctp_sock *sp;
589 unsigned short port;
590
591 sp = sctp_sk(asoc->base.sk);
592
593 /* AF_INET and AF_INET6 share common port field. */
594 port = ntohs(addr->v4.sin_port);
595
596 pr_debug("%s: association:%p addr:%pISpc state:%d\n", __func__,
597 asoc, &addr->sa, peer_state);
598
599 /* Set the port if it has not been set yet. */
600 if (0 == asoc->peer.port)
601 asoc->peer.port = port;
602
603 /* Check to see if this is a duplicate. */
604 peer = sctp_assoc_lookup_paddr(asoc, addr);
605 if (peer) {
606 /* An UNKNOWN state is only set on transports added by
607 * user in sctp_connectx() call. Such transports should be
608 * considered CONFIRMED per RFC 4960, Section 5.4.
609 */
610 if (peer->state == SCTP_UNKNOWN) {
611 peer->state = SCTP_ACTIVE;
612 }
613 return peer;
614 }
615
616 peer = sctp_transport_new(asoc->base.net, addr, gfp);
617 if (!peer)
618 return NULL;
619
620 sctp_transport_set_owner(peer, asoc);
621
622 /* Initialize the peer's heartbeat interval based on the
623 * association configured value.
624 */
625 peer->hbinterval = asoc->hbinterval;
626 peer->probe_interval = asoc->probe_interval;
627
628 peer->encap_port = asoc->encap_port;
629
630 /* Set the path max_retrans. */
631 peer->pathmaxrxt = asoc->pathmaxrxt;
632
633 /* And the partial failure retrans threshold */
634 peer->pf_retrans = asoc->pf_retrans;
635 /* And the primary path switchover retrans threshold */
636 peer->ps_retrans = asoc->ps_retrans;
637
638 /* Initialize the peer's SACK delay timeout based on the
639 * association configured value.
640 */
641 peer->sackdelay = asoc->sackdelay;
642 peer->sackfreq = asoc->sackfreq;
643
644 if (addr->sa.sa_family == AF_INET6) {
645 __be32 info = addr->v6.sin6_flowinfo;
646
647 if (info) {
648 peer->flowlabel = ntohl(info & IPV6_FLOWLABEL_MASK);
649 peer->flowlabel |= SCTP_FLOWLABEL_SET_MASK;
650 } else {
651 peer->flowlabel = asoc->flowlabel;
652 }
653 }
654 peer->dscp = asoc->dscp;
655
656 /* Enable/disable heartbeat, SACK delay, and path MTU discovery
657 * based on association setting.
658 */
659 peer->param_flags = asoc->param_flags;
660
661 /* Initialize the pmtu of the transport. */
662 sctp_transport_route(peer, NULL, sp);
663
664 /* If this is the first transport addr on this association,
665 * initialize the association PMTU to the peer's PMTU.
666 * If not and the current association PMTU is higher than the new
667 * peer's PMTU, reset the association PMTU to the new peer's PMTU.
668 */
669 sctp_assoc_set_pmtu(asoc, asoc->pathmtu ?
670 min_t(int, peer->pathmtu, asoc->pathmtu) :
671 peer->pathmtu);
672
673 peer->pmtu_pending = 0;
674
675 /* The asoc->peer.port might not be meaningful yet, but
676 * initialize the packet structure anyway.
677 */
678 sctp_packet_init(&peer->packet, peer, asoc->base.bind_addr.port,
679 asoc->peer.port);
680
681 /* 7.2.1 Slow-Start
682 *
683 * o The initial cwnd before DATA transmission or after a sufficiently
684 * long idle period MUST be set to
685 * min(4*MTU, max(2*MTU, 4380 bytes))
686 *
687 * o The initial value of ssthresh MAY be arbitrarily high
688 * (for example, implementations MAY use the size of the
689 * receiver advertised window).
690 */
691 peer->cwnd = min(4*asoc->pathmtu, max_t(__u32, 2*asoc->pathmtu, 4380));
692
693 /* At this point, we may not have the receiver's advertised window,
694 * so initialize ssthresh to the default value and it will be set
695 * later when we process the INIT.
696 */
697 peer->ssthresh = SCTP_DEFAULT_MAXWINDOW;
698
699 peer->partial_bytes_acked = 0;
700 peer->flight_size = 0;
701 peer->burst_limited = 0;
702
703 /* Set the transport's RTO.initial value */
704 peer->rto = asoc->rto_initial;
705 sctp_max_rto(asoc, peer);
706
707 /* Set the peer's active state. */
708 peer->state = peer_state;
709
710 /* Add this peer into the transport hashtable */
711 if (sctp_hash_transport(peer)) {
712 sctp_transport_free(peer);
713 return NULL;
714 }
715
716 sctp_transport_pl_reset(peer);
717
718 /* Attach the remote transport to our asoc. */
719 list_add_tail_rcu(&peer->transports, &asoc->peer.transport_addr_list);
720 asoc->peer.transport_count++;
721
722 sctp_ulpevent_notify_peer_addr_change(peer, SCTP_ADDR_ADDED, 0);
723
724 /* If we do not yet have a primary path, set one. */
725 if (!asoc->peer.primary_path) {
726 sctp_assoc_set_primary(asoc, peer);
727 asoc->peer.retran_path = peer;
728 }
729
730 if (asoc->peer.active_path == asoc->peer.retran_path &&
731 peer->state != SCTP_UNCONFIRMED) {
732 asoc->peer.retran_path = peer;
733 }
734
735 return peer;
736 }
737
738 /* Delete a transport address from an association. */
739 void sctp_assoc_del_peer(struct sctp_association *asoc,
740 const union sctp_addr *addr)
741 {
742 struct list_head *pos;
743 struct list_head *temp;
744 struct sctp_transport *transport;
745
746 list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
747 transport = list_entry(pos, struct sctp_transport, transports);
748 if (sctp_cmp_addr_exact(addr, &transport->ipaddr)) {
749 /* Do book keeping for removing the peer and free it. */
750 sctp_assoc_rm_peer(asoc, transport);
751 break;
752 }
753 }
754 }
755
756 /* Lookup a transport by address. */
757 struct sctp_transport *sctp_assoc_lookup_paddr(
758 const struct sctp_association *asoc,
759 const union sctp_addr *address)
760 {
761 struct sctp_transport *t;
762
763 /* Cycle through all transports searching for a peer address. */
764
765 list_for_each_entry(t, &asoc->peer.transport_addr_list,
766 transports) {
767 if (sctp_cmp_addr_exact(address, &t->ipaddr))
768 return t;
769 }
770
771 return NULL;
772 }
773
774 /* Remove all transports except a give one */
775 void sctp_assoc_del_nonprimary_peers(struct sctp_association *asoc,
776 struct sctp_transport *primary)
777 {
778 struct sctp_transport *temp;
779 struct sctp_transport *t;
780
781 list_for_each_entry_safe(t, temp, &asoc->peer.transport_addr_list,
782 transports) {
783 /* if the current transport is not the primary one, delete it */
784 if (t != primary)
785 sctp_assoc_rm_peer(asoc, t);
786 }
787 }
788
789 /* Engage in transport control operations.
790 * Mark the transport up or down and send a notification to the user.
791 * Select and update the new active and retran paths.
792 */
793 void sctp_assoc_control_transport(struct sctp_association *asoc,
794 struct sctp_transport *transport,
795 enum sctp_transport_cmd command,
796 sctp_sn_error_t error)
797 {
798 int spc_state = SCTP_ADDR_AVAILABLE;
799 bool ulp_notify = true;
800
801 /* Record the transition on the transport. */
802 switch (command) {
803 case SCTP_TRANSPORT_UP:
804 /* If we are moving from UNCONFIRMED state due
805 * to heartbeat success, report the SCTP_ADDR_CONFIRMED
806 * state to the user, otherwise report SCTP_ADDR_AVAILABLE.
807 */
808 if (transport->state == SCTP_PF &&
809 asoc->pf_expose != SCTP_PF_EXPOSE_ENABLE)
810 ulp_notify = false;
811 else if (transport->state == SCTP_UNCONFIRMED &&
812 error == SCTP_HEARTBEAT_SUCCESS)
813 spc_state = SCTP_ADDR_CONFIRMED;
814
815 transport->state = SCTP_ACTIVE;
816 sctp_transport_pl_reset(transport);
817 break;
818
819 case SCTP_TRANSPORT_DOWN:
820 /* If the transport was never confirmed, do not transition it
821 * to inactive state. Also, release the cached route since
822 * there may be a better route next time.
823 */
824 if (transport->state != SCTP_UNCONFIRMED) {
825 transport->state = SCTP_INACTIVE;
826 sctp_transport_pl_reset(transport);
827 spc_state = SCTP_ADDR_UNREACHABLE;
828 } else {
829 sctp_transport_dst_release(transport);
830 ulp_notify = false;
831 }
832 break;
833
834 case SCTP_TRANSPORT_PF:
835 transport->state = SCTP_PF;
836 if (asoc->pf_expose != SCTP_PF_EXPOSE_ENABLE)
837 ulp_notify = false;
838 else
839 spc_state = SCTP_ADDR_POTENTIALLY_FAILED;
840 break;
841
842 default:
843 return;
844 }
845
846 /* Generate and send a SCTP_PEER_ADDR_CHANGE notification
847 * to the user.
848 */
849 if (ulp_notify)
850 sctp_ulpevent_notify_peer_addr_change(transport,
851 spc_state, error);
852
853 /* Select new active and retran paths. */
854 sctp_select_active_and_retran_path(asoc);
855 }
856
857 /* Hold a reference to an association. */
858 void sctp_association_hold(struct sctp_association *asoc)
859 {
860 refcount_inc(&asoc->base.refcnt);
861 }
862
863 /* Release a reference to an association and cleanup
864 * if there are no more references.
865 */
866 void sctp_association_put(struct sctp_association *asoc)
867 {
868 if (refcount_dec_and_test(&asoc->base.refcnt))
869 sctp_association_destroy(asoc);
870 }
871
872 /* Allocate the next TSN, Transmission Sequence Number, for the given
873 * association.
874 */
875 __u32 sctp_association_get_next_tsn(struct sctp_association *asoc)
876 {
877 /* From Section 1.6 Serial Number Arithmetic:
878 * Transmission Sequence Numbers wrap around when they reach
879 * 2**32 - 1. That is, the next TSN a DATA chunk MUST use
880 * after transmitting TSN = 2*32 - 1 is TSN = 0.
881 */
882 __u32 retval = asoc->next_tsn;
883 asoc->next_tsn++;
884 asoc->unack_data++;
885
886 return retval;
887 }
888
889 /* Compare two addresses to see if they match. Wildcard addresses
890 * only match themselves.
891 */
892 int sctp_cmp_addr_exact(const union sctp_addr *ss1,
893 const union sctp_addr *ss2)
894 {
895 struct sctp_af *af;
896
897 af = sctp_get_af_specific(ss1->sa.sa_family);
898 if (unlikely(!af))
899 return 0;
900
901 return af->cmp_addr(ss1, ss2);
902 }
903
904 /* Return an ecne chunk to get prepended to a packet.
905 * Note: We are sly and return a shared, prealloced chunk. FIXME:
906 * No we don't, but we could/should.
907 */
908 struct sctp_chunk *sctp_get_ecne_prepend(struct sctp_association *asoc)
909 {
910 if (!asoc->need_ecne)
911 return NULL;
912
913 /* Send ECNE if needed.
914 * Not being able to allocate a chunk here is not deadly.
915 */
916 return sctp_make_ecne(asoc, asoc->last_ecne_tsn);
917 }
918
919 /*
920 * Find which transport this TSN was sent on.
921 */
922 struct sctp_transport *sctp_assoc_lookup_tsn(struct sctp_association *asoc,
923 __u32 tsn)
924 {
925 struct sctp_transport *active;
926 struct sctp_transport *match;
927 struct sctp_transport *transport;
928 struct sctp_chunk *chunk;
929 __be32 key = htonl(tsn);
930
931 match = NULL;
932
933 /*
934 * FIXME: In general, find a more efficient data structure for
935 * searching.
936 */
937
938 /*
939 * The general strategy is to search each transport's transmitted
940 * list. Return which transport this TSN lives on.
941 *
942 * Let's be hopeful and check the active_path first.
943 * Another optimization would be to know if there is only one
944 * outbound path and not have to look for the TSN at all.
945 *
946 */
947
948 active = asoc->peer.active_path;
949
950 list_for_each_entry(chunk, &active->transmitted,
951 transmitted_list) {
952
953 if (key == chunk->subh.data_hdr->tsn) {
954 match = active;
955 goto out;
956 }
957 }
958
959 /* If not found, go search all the other transports. */
960 list_for_each_entry(transport, &asoc->peer.transport_addr_list,
961 transports) {
962
963 if (transport == active)
964 continue;
965 list_for_each_entry(chunk, &transport->transmitted,
966 transmitted_list) {
967 if (key == chunk->subh.data_hdr->tsn) {
968 match = transport;
969 goto out;
970 }
971 }
972 }
973 out:
974 return match;
975 }
976
977 /* Do delayed input processing. This is scheduled by sctp_rcv(). */
978 static void sctp_assoc_bh_rcv(struct work_struct *work)
979 {
980 struct sctp_association *asoc =
981 container_of(work, struct sctp_association,
982 base.inqueue.immediate);
983 struct net *net = asoc->base.net;
984 union sctp_subtype subtype;
985 struct sctp_endpoint *ep;
986 struct sctp_chunk *chunk;
987 struct sctp_inq *inqueue;
988 int first_time = 1; /* is this the first time through the loop */
989 int error = 0;
990 int state;
991
992 /* The association should be held so we should be safe. */
993 ep = asoc->ep;
994
995 inqueue = &asoc->base.inqueue;
996 sctp_association_hold(asoc);
997 while (NULL != (chunk = sctp_inq_pop(inqueue))) {
998 state = asoc->state;
999 subtype = SCTP_ST_CHUNK(chunk->chunk_hdr->type);
1000
1001 /* If the first chunk in the packet is AUTH, do special
1002 * processing specified in Section 6.3 of SCTP-AUTH spec
1003 */
1004 if (first_time && subtype.chunk == SCTP_CID_AUTH) {
1005 struct sctp_chunkhdr *next_hdr;
1006
1007 next_hdr = sctp_inq_peek(inqueue);
1008 if (!next_hdr)
1009 goto normal;
1010
1011 /* If the next chunk is COOKIE-ECHO, skip the AUTH
1012 * chunk while saving a pointer to it so we can do
1013 * Authentication later (during cookie-echo
1014 * processing).
1015 */
1016 if (next_hdr->type == SCTP_CID_COOKIE_ECHO) {
1017 chunk->auth_chunk = skb_clone(chunk->skb,
1018 GFP_ATOMIC);
1019 chunk->auth = 1;
1020 continue;
1021 }
1022 }
1023
1024 normal:
1025 /* SCTP-AUTH, Section 6.3:
1026 * The receiver has a list of chunk types which it expects
1027 * to be received only after an AUTH-chunk. This list has
1028 * been sent to the peer during the association setup. It
1029 * MUST silently discard these chunks if they are not placed
1030 * after an AUTH chunk in the packet.
1031 */
1032 if (sctp_auth_recv_cid(subtype.chunk, asoc) && !chunk->auth)
1033 continue;
1034
1035 /* Remember where the last DATA chunk came from so we
1036 * know where to send the SACK.
1037 */
1038 if (sctp_chunk_is_data(chunk))
1039 asoc->peer.last_data_from = chunk->transport;
1040 else {
1041 SCTP_INC_STATS(net, SCTP_MIB_INCTRLCHUNKS);
1042 asoc->stats.ictrlchunks++;
1043 if (chunk->chunk_hdr->type == SCTP_CID_SACK)
1044 asoc->stats.isacks++;
1045 }
1046
1047 if (chunk->transport)
1048 chunk->transport->last_time_heard = ktime_get();
1049
1050 /* Run through the state machine. */
1051 error = sctp_do_sm(net, SCTP_EVENT_T_CHUNK, subtype,
1052 state, ep, asoc, chunk, GFP_ATOMIC);
1053
1054 /* Check to see if the association is freed in response to
1055 * the incoming chunk. If so, get out of the while loop.
1056 */
1057 if (asoc->base.dead)
1058 break;
1059
1060 /* If there is an error on chunk, discard this packet. */
1061 if (error && chunk)
1062 chunk->pdiscard = 1;
1063
1064 if (first_time)
1065 first_time = 0;
1066 }
1067 sctp_association_put(asoc);
1068 }
1069
1070 /* This routine moves an association from its old sk to a new sk. */
1071 void sctp_assoc_migrate(struct sctp_association *assoc, struct sock *newsk)
1072 {
1073 struct sctp_sock *newsp = sctp_sk(newsk);
1074 struct sock *oldsk = assoc->base.sk;
1075
1076 /* Delete the association from the old endpoint's list of
1077 * associations.
1078 */
1079 list_del_init(&assoc->asocs);
1080
1081 /* Decrement the backlog value for a TCP-style socket. */
1082 if (sctp_style(oldsk, TCP))
1083 sk_acceptq_removed(oldsk);
1084
1085 /* Release references to the old endpoint and the sock. */
1086 sctp_endpoint_put(assoc->ep);
1087 sock_put(assoc->base.sk);
1088
1089 /* Get a reference to the new endpoint. */
1090 assoc->ep = newsp->ep;
1091 sctp_endpoint_hold(assoc->ep);
1092
1093 /* Get a reference to the new sock. */
1094 assoc->base.sk = newsk;
1095 sock_hold(assoc->base.sk);
1096
1097 /* Add the association to the new endpoint's list of associations. */
1098 sctp_endpoint_add_asoc(newsp->ep, assoc);
1099 }
1100
1101 /* Update an association (possibly from unexpected COOKIE-ECHO processing). */
1102 int sctp_assoc_update(struct sctp_association *asoc,
1103 struct sctp_association *new)
1104 {
1105 struct sctp_transport *trans;
1106 struct list_head *pos, *temp;
1107
1108 /* Copy in new parameters of peer. */
1109 asoc->c = new->c;
1110 asoc->peer.rwnd = new->peer.rwnd;
1111 asoc->peer.sack_needed = new->peer.sack_needed;
1112 asoc->peer.auth_capable = new->peer.auth_capable;
1113 asoc->peer.i = new->peer.i;
1114
1115 if (!sctp_tsnmap_init(&asoc->peer.tsn_map, SCTP_TSN_MAP_INITIAL,
1116 asoc->peer.i.initial_tsn, GFP_ATOMIC))
1117 return -ENOMEM;
1118
1119 /* Remove any peer addresses not present in the new association. */
1120 list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
1121 trans = list_entry(pos, struct sctp_transport, transports);
1122 if (!sctp_assoc_lookup_paddr(new, &trans->ipaddr)) {
1123 sctp_assoc_rm_peer(asoc, trans);
1124 continue;
1125 }
1126
1127 if (asoc->state >= SCTP_STATE_ESTABLISHED)
1128 sctp_transport_reset(trans);
1129 }
1130
1131 /* If the case is A (association restart), use
1132 * initial_tsn as next_tsn. If the case is B, use
1133 * current next_tsn in case data sent to peer
1134 * has been discarded and needs retransmission.
1135 */
1136 if (asoc->state >= SCTP_STATE_ESTABLISHED) {
1137 asoc->next_tsn = new->next_tsn;
1138 asoc->ctsn_ack_point = new->ctsn_ack_point;
1139 asoc->adv_peer_ack_point = new->adv_peer_ack_point;
1140
1141 /* Reinitialize SSN for both local streams
1142 * and peer's streams.
1143 */
1144 sctp_stream_clear(&asoc->stream);
1145
1146 /* Flush the ULP reassembly and ordered queue.
1147 * Any data there will now be stale and will
1148 * cause problems.
1149 */
1150 sctp_ulpq_flush(&asoc->ulpq);
1151
1152 /* reset the overall association error count so
1153 * that the restarted association doesn't get torn
1154 * down on the next retransmission timer.
1155 */
1156 asoc->overall_error_count = 0;
1157
1158 } else {
1159 /* Add any peer addresses from the new association. */
1160 list_for_each_entry(trans, &new->peer.transport_addr_list,
1161 transports)
1162 if (!sctp_assoc_add_peer(asoc, &trans->ipaddr,
1163 GFP_ATOMIC, trans->state))
1164 return -ENOMEM;
1165
1166 asoc->ctsn_ack_point = asoc->next_tsn - 1;
1167 asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
1168
1169 if (sctp_state(asoc, COOKIE_WAIT))
1170 sctp_stream_update(&asoc->stream, &new->stream);
1171
1172 /* get a new assoc id if we don't have one yet. */
1173 if (sctp_assoc_set_id(asoc, GFP_ATOMIC))
1174 return -ENOMEM;
1175 }
1176
1177 /* SCTP-AUTH: Save the peer parameters from the new associations
1178 * and also move the association shared keys over
1179 */
1180 kfree(asoc->peer.peer_random);
1181 asoc->peer.peer_random = new->peer.peer_random;
1182 new->peer.peer_random = NULL;
1183
1184 kfree(asoc->peer.peer_chunks);
1185 asoc->peer.peer_chunks = new->peer.peer_chunks;
1186 new->peer.peer_chunks = NULL;
1187
1188 kfree(asoc->peer.peer_hmacs);
1189 asoc->peer.peer_hmacs = new->peer.peer_hmacs;
1190 new->peer.peer_hmacs = NULL;
1191
1192 return sctp_auth_asoc_init_active_key(asoc, GFP_ATOMIC);
1193 }
1194
1195 /* Update the retran path for sending a retransmitted packet.
1196 * See also RFC4960, 6.4. Multi-Homed SCTP Endpoints:
1197 *
1198 * When there is outbound data to send and the primary path
1199 * becomes inactive (e.g., due to failures), or where the
1200 * SCTP user explicitly requests to send data to an
1201 * inactive destination transport address, before reporting
1202 * an error to its ULP, the SCTP endpoint should try to send
1203 * the data to an alternate active destination transport
1204 * address if one exists.
1205 *
1206 * When retransmitting data that timed out, if the endpoint
1207 * is multihomed, it should consider each source-destination
1208 * address pair in its retransmission selection policy.
1209 * When retransmitting timed-out data, the endpoint should
1210 * attempt to pick the most divergent source-destination
1211 * pair from the original source-destination pair to which
1212 * the packet was transmitted.
1213 *
1214 * Note: Rules for picking the most divergent source-destination
1215 * pair are an implementation decision and are not specified
1216 * within this document.
1217 *
1218 * Our basic strategy is to round-robin transports in priorities
1219 * according to sctp_trans_score() e.g., if no such
1220 * transport with state SCTP_ACTIVE exists, round-robin through
1221 * SCTP_UNKNOWN, etc. You get the picture.
1222 */
1223 static u8 sctp_trans_score(const struct sctp_transport *trans)
1224 {
1225 switch (trans->state) {
1226 case SCTP_ACTIVE:
1227 return 3; /* best case */
1228 case SCTP_UNKNOWN:
1229 return 2;
1230 case SCTP_PF:
1231 return 1;
1232 default: /* case SCTP_INACTIVE */
1233 return 0; /* worst case */
1234 }
1235 }
1236
1237 static struct sctp_transport *sctp_trans_elect_tie(struct sctp_transport *trans1,
1238 struct sctp_transport *trans2)
1239 {
1240 if (trans1->error_count > trans2->error_count) {
1241 return trans2;
1242 } else if (trans1->error_count == trans2->error_count &&
1243 ktime_after(trans2->last_time_heard,
1244 trans1->last_time_heard)) {
1245 return trans2;
1246 } else {
1247 return trans1;
1248 }
1249 }
1250
1251 static struct sctp_transport *sctp_trans_elect_best(struct sctp_transport *curr,
1252 struct sctp_transport *best)
1253 {
1254 u8 score_curr, score_best;
1255
1256 if (best == NULL || curr == best)
1257 return curr;
1258
1259 score_curr = sctp_trans_score(curr);
1260 score_best = sctp_trans_score(best);
1261
1262 /* First, try a score-based selection if both transport states
1263 * differ. If we're in a tie, lets try to make a more clever
1264 * decision here based on error counts and last time heard.
1265 */
1266 if (score_curr > score_best)
1267 return curr;
1268 else if (score_curr == score_best)
1269 return sctp_trans_elect_tie(best, curr);
1270 else
1271 return best;
1272 }
1273
1274 void sctp_assoc_update_retran_path(struct sctp_association *asoc)
1275 {
1276 struct sctp_transport *trans = asoc->peer.retran_path;
1277 struct sctp_transport *trans_next = NULL;
1278
1279 /* We're done as we only have the one and only path. */
1280 if (asoc->peer.transport_count == 1)
1281 return;
1282 /* If active_path and retran_path are the same and active,
1283 * then this is the only active path. Use it.
1284 */
1285 if (asoc->peer.active_path == asoc->peer.retran_path &&
1286 asoc->peer.active_path->state == SCTP_ACTIVE)
1287 return;
1288
1289 /* Iterate from retran_path's successor back to retran_path. */
1290 for (trans = list_next_entry(trans, transports); 1;
1291 trans = list_next_entry(trans, transports)) {
1292 /* Manually skip the head element. */
1293 if (&trans->transports == &asoc->peer.transport_addr_list)
1294 continue;
1295 if (trans->state == SCTP_UNCONFIRMED)
1296 continue;
1297 trans_next = sctp_trans_elect_best(trans, trans_next);
1298 /* Active is good enough for immediate return. */
1299 if (trans_next->state == SCTP_ACTIVE)
1300 break;
1301 /* We've reached the end, time to update path. */
1302 if (trans == asoc->peer.retran_path)
1303 break;
1304 }
1305
1306 asoc->peer.retran_path = trans_next;
1307
1308 pr_debug("%s: association:%p updated new path to addr:%pISpc\n",
1309 __func__, asoc, &asoc->peer.retran_path->ipaddr.sa);
1310 }
1311
1312 static void sctp_select_active_and_retran_path(struct sctp_association *asoc)
1313 {
1314 struct sctp_transport *trans, *trans_pri = NULL, *trans_sec = NULL;
1315 struct sctp_transport *trans_pf = NULL;
1316
1317 /* Look for the two most recently used active transports. */
1318 list_for_each_entry(trans, &asoc->peer.transport_addr_list,
1319 transports) {
1320 /* Skip uninteresting transports. */
1321 if (trans->state == SCTP_INACTIVE ||
1322 trans->state == SCTP_UNCONFIRMED)
1323 continue;
1324 /* Keep track of the best PF transport from our
1325 * list in case we don't find an active one.
1326 */
1327 if (trans->state == SCTP_PF) {
1328 trans_pf = sctp_trans_elect_best(trans, trans_pf);
1329 continue;
1330 }
1331 /* For active transports, pick the most recent ones. */
1332 if (trans_pri == NULL ||
1333 ktime_after(trans->last_time_heard,
1334 trans_pri->last_time_heard)) {
1335 trans_sec = trans_pri;
1336 trans_pri = trans;
1337 } else if (trans_sec == NULL ||
1338 ktime_after(trans->last_time_heard,
1339 trans_sec->last_time_heard)) {
1340 trans_sec = trans;
1341 }
1342 }
1343
1344 /* RFC 2960 6.4 Multi-Homed SCTP Endpoints
1345 *
1346 * By default, an endpoint should always transmit to the primary
1347 * path, unless the SCTP user explicitly specifies the
1348 * destination transport address (and possibly source transport
1349 * address) to use. [If the primary is active but not most recent,
1350 * bump the most recently used transport.]
1351 */
1352 if ((asoc->peer.primary_path->state == SCTP_ACTIVE ||
1353 asoc->peer.primary_path->state == SCTP_UNKNOWN) &&
1354 asoc->peer.primary_path != trans_pri) {
1355 trans_sec = trans_pri;
1356 trans_pri = asoc->peer.primary_path;
1357 }
1358
1359 /* We did not find anything useful for a possible retransmission
1360 * path; either primary path that we found is the same as
1361 * the current one, or we didn't generally find an active one.
1362 */
1363 if (trans_sec == NULL)
1364 trans_sec = trans_pri;
1365
1366 /* If we failed to find a usable transport, just camp on the
1367 * active or pick a PF iff it's the better choice.
1368 */
1369 if (trans_pri == NULL) {
1370 trans_pri = sctp_trans_elect_best(asoc->peer.active_path, trans_pf);
1371 trans_sec = trans_pri;
1372 }
1373
1374 /* Set the active and retran transports. */
1375 asoc->peer.active_path = trans_pri;
1376 asoc->peer.retran_path = trans_sec;
1377 }
1378
1379 struct sctp_transport *
1380 sctp_assoc_choose_alter_transport(struct sctp_association *asoc,
1381 struct sctp_transport *last_sent_to)
1382 {
1383 /* If this is the first time packet is sent, use the active path,
1384 * else use the retran path. If the last packet was sent over the
1385 * retran path, update the retran path and use it.
1386 */
1387 if (last_sent_to == NULL) {
1388 return asoc->peer.active_path;
1389 } else {
1390 if (last_sent_to == asoc->peer.retran_path)
1391 sctp_assoc_update_retran_path(asoc);
1392
1393 return asoc->peer.retran_path;
1394 }
1395 }
1396
1397 void sctp_assoc_update_frag_point(struct sctp_association *asoc)
1398 {
1399 int frag = sctp_mtu_payload(sctp_sk(asoc->base.sk), asoc->pathmtu,
1400 sctp_datachk_len(&asoc->stream));
1401
1402 if (asoc->user_frag)
1403 frag = min_t(int, frag, asoc->user_frag);
1404
1405 frag = min_t(int, frag, SCTP_MAX_CHUNK_LEN -
1406 sctp_datachk_len(&asoc->stream));
1407
1408 asoc->frag_point = SCTP_TRUNC4(frag);
1409 }
1410
1411 void sctp_assoc_set_pmtu(struct sctp_association *asoc, __u32 pmtu)
1412 {
1413 if (asoc->pathmtu != pmtu) {
1414 asoc->pathmtu = pmtu;
1415 sctp_assoc_update_frag_point(asoc);
1416 }
1417
1418 pr_debug("%s: asoc:%p, pmtu:%d, frag_point:%d\n", __func__, asoc,
1419 asoc->pathmtu, asoc->frag_point);
1420 }
1421
1422 /* Update the association's pmtu and frag_point by going through all the
1423 * transports. This routine is called when a transport's PMTU has changed.
1424 */
1425 void sctp_assoc_sync_pmtu(struct sctp_association *asoc)
1426 {
1427 struct sctp_transport *t;
1428 __u32 pmtu = 0;
1429
1430 if (!asoc)
1431 return;
1432
1433 /* Get the lowest pmtu of all the transports. */
1434 list_for_each_entry(t, &asoc->peer.transport_addr_list, transports) {
1435 if (t->pmtu_pending && t->dst) {
1436 sctp_transport_update_pmtu(t,
1437 atomic_read(&t->mtu_info));
1438 t->pmtu_pending = 0;
1439 }
1440 if (!pmtu || (t->pathmtu < pmtu))
1441 pmtu = t->pathmtu;
1442 }
1443
1444 sctp_assoc_set_pmtu(asoc, pmtu);
1445 }
1446
1447 /* Should we send a SACK to update our peer? */
1448 static inline bool sctp_peer_needs_update(struct sctp_association *asoc)
1449 {
1450 struct net *net = asoc->base.net;
1451
1452 switch (asoc->state) {
1453 case SCTP_STATE_ESTABLISHED:
1454 case SCTP_STATE_SHUTDOWN_PENDING:
1455 case SCTP_STATE_SHUTDOWN_RECEIVED:
1456 case SCTP_STATE_SHUTDOWN_SENT:
1457 if ((asoc->rwnd > asoc->a_rwnd) &&
1458 ((asoc->rwnd - asoc->a_rwnd) >= max_t(__u32,
1459 (asoc->base.sk->sk_rcvbuf >> net->sctp.rwnd_upd_shift),
1460 asoc->pathmtu)))
1461 return true;
1462 break;
1463 default:
1464 break;
1465 }
1466 return false;
1467 }
1468
1469 /* Increase asoc's rwnd by len and send any window update SACK if needed. */
1470 void sctp_assoc_rwnd_increase(struct sctp_association *asoc, unsigned int len)
1471 {
1472 struct sctp_chunk *sack;
1473 struct timer_list *timer;
1474
1475 if (asoc->rwnd_over) {
1476 if (asoc->rwnd_over >= len) {
1477 asoc->rwnd_over -= len;
1478 } else {
1479 asoc->rwnd += (len - asoc->rwnd_over);
1480 asoc->rwnd_over = 0;
1481 }
1482 } else {
1483 asoc->rwnd += len;
1484 }
1485
1486 /* If we had window pressure, start recovering it
1487 * once our rwnd had reached the accumulated pressure
1488 * threshold. The idea is to recover slowly, but up
1489 * to the initial advertised window.
1490 */
1491 if (asoc->rwnd_press) {
1492 int change = min(asoc->pathmtu, asoc->rwnd_press);
1493 asoc->rwnd += change;
1494 asoc->rwnd_press -= change;
1495 }
1496
1497 pr_debug("%s: asoc:%p rwnd increased by %d to (%u, %u) - %u\n",
1498 __func__, asoc, len, asoc->rwnd, asoc->rwnd_over,
1499 asoc->a_rwnd);
1500
1501 /* Send a window update SACK if the rwnd has increased by at least the
1502 * minimum of the association's PMTU and half of the receive buffer.
1503 * The algorithm used is similar to the one described in
1504 * Section 4.2.3.3 of RFC 1122.
1505 */
1506 if (sctp_peer_needs_update(asoc)) {
1507 asoc->a_rwnd = asoc->rwnd;
1508
1509 pr_debug("%s: sending window update SACK- asoc:%p rwnd:%u "
1510 "a_rwnd:%u\n", __func__, asoc, asoc->rwnd,
1511 asoc->a_rwnd);
1512
1513 sack = sctp_make_sack(asoc);
1514 if (!sack)
1515 return;
1516
1517 asoc->peer.sack_needed = 0;
1518
1519 sctp_outq_tail(&asoc->outqueue, sack, GFP_ATOMIC);
1520
1521 /* Stop the SACK timer. */
1522 timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK];
1523 if (del_timer(timer))
1524 sctp_association_put(asoc);
1525 }
1526 }
1527
1528 /* Decrease asoc's rwnd by len. */
1529 void sctp_assoc_rwnd_decrease(struct sctp_association *asoc, unsigned int len)
1530 {
1531 int rx_count;
1532 int over = 0;
1533
1534 if (unlikely(!asoc->rwnd || asoc->rwnd_over))
1535 pr_debug("%s: association:%p has asoc->rwnd:%u, "
1536 "asoc->rwnd_over:%u!\n", __func__, asoc,
1537 asoc->rwnd, asoc->rwnd_over);
1538
1539 if (asoc->ep->rcvbuf_policy)
1540 rx_count = atomic_read(&asoc->rmem_alloc);
1541 else
1542 rx_count = atomic_read(&asoc->base.sk->sk_rmem_alloc);
1543
1544 /* If we've reached or overflowed our receive buffer, announce
1545 * a 0 rwnd if rwnd would still be positive. Store the
1546 * potential pressure overflow so that the window can be restored
1547 * back to original value.
1548 */
1549 if (rx_count >= asoc->base.sk->sk_rcvbuf)
1550 over = 1;
1551
1552 if (asoc->rwnd >= len) {
1553 asoc->rwnd -= len;
1554 if (over) {
1555 asoc->rwnd_press += asoc->rwnd;
1556 asoc->rwnd = 0;
1557 }
1558 } else {
1559 asoc->rwnd_over += len - asoc->rwnd;
1560 asoc->rwnd = 0;
1561 }
1562
1563 pr_debug("%s: asoc:%p rwnd decreased by %d to (%u, %u, %u)\n",
1564 __func__, asoc, len, asoc->rwnd, asoc->rwnd_over,
1565 asoc->rwnd_press);
1566 }
1567
1568 /* Build the bind address list for the association based on info from the
1569 * local endpoint and the remote peer.
1570 */
1571 int sctp_assoc_set_bind_addr_from_ep(struct sctp_association *asoc,
1572 enum sctp_scope scope, gfp_t gfp)
1573 {
1574 struct sock *sk = asoc->base.sk;
1575 int flags;
1576
1577 /* Use scoping rules to determine the subset of addresses from
1578 * the endpoint.
1579 */
1580 flags = (PF_INET6 == sk->sk_family) ? SCTP_ADDR6_ALLOWED : 0;
1581 if (!inet_v6_ipv6only(sk))
1582 flags |= SCTP_ADDR4_ALLOWED;
1583 if (asoc->peer.ipv4_address)
1584 flags |= SCTP_ADDR4_PEERSUPP;
1585 if (asoc->peer.ipv6_address)
1586 flags |= SCTP_ADDR6_PEERSUPP;
1587
1588 return sctp_bind_addr_copy(asoc->base.net,
1589 &asoc->base.bind_addr,
1590 &asoc->ep->base.bind_addr,
1591 scope, gfp, flags);
1592 }
1593
1594 /* Build the association's bind address list from the cookie. */
1595 int sctp_assoc_set_bind_addr_from_cookie(struct sctp_association *asoc,
1596 struct sctp_cookie *cookie,
1597 gfp_t gfp)
1598 {
1599 struct sctp_init_chunk *peer_init = (struct sctp_init_chunk *)(cookie + 1);
1600 int var_size2 = ntohs(peer_init->chunk_hdr.length);
1601 int var_size3 = cookie->raw_addr_list_len;
1602 __u8 *raw = (__u8 *)peer_init + var_size2;
1603
1604 return sctp_raw_to_bind_addrs(&asoc->base.bind_addr, raw, var_size3,
1605 asoc->ep->base.bind_addr.port, gfp);
1606 }
1607
1608 /* Lookup laddr in the bind address list of an association. */
1609 int sctp_assoc_lookup_laddr(struct sctp_association *asoc,
1610 const union sctp_addr *laddr)
1611 {
1612 int found = 0;
1613
1614 if ((asoc->base.bind_addr.port == ntohs(laddr->v4.sin_port)) &&
1615 sctp_bind_addr_match(&asoc->base.bind_addr, laddr,
1616 sctp_sk(asoc->base.sk)))
1617 found = 1;
1618
1619 return found;
1620 }
1621
1622 /* Set an association id for a given association */
1623 int sctp_assoc_set_id(struct sctp_association *asoc, gfp_t gfp)
1624 {
1625 bool preload = gfpflags_allow_blocking(gfp);
1626 int ret;
1627
1628 /* If the id is already assigned, keep it. */
1629 if (asoc->assoc_id)
1630 return 0;
1631
1632 if (preload)
1633 idr_preload(gfp);
1634 spin_lock_bh(&sctp_assocs_id_lock);
1635 /* 0, 1, 2 are used as SCTP_FUTURE_ASSOC, SCTP_CURRENT_ASSOC and
1636 * SCTP_ALL_ASSOC, so an available id must be > SCTP_ALL_ASSOC.
1637 */
1638 ret = idr_alloc_cyclic(&sctp_assocs_id, asoc, SCTP_ALL_ASSOC + 1, 0,
1639 GFP_NOWAIT);
1640 spin_unlock_bh(&sctp_assocs_id_lock);
1641 if (preload)
1642 idr_preload_end();
1643 if (ret < 0)
1644 return ret;
1645
1646 asoc->assoc_id = (sctp_assoc_t)ret;
1647 return 0;
1648 }
1649
1650 /* Free the ASCONF queue */
1651 static void sctp_assoc_free_asconf_queue(struct sctp_association *asoc)
1652 {
1653 struct sctp_chunk *asconf;
1654 struct sctp_chunk *tmp;
1655
1656 list_for_each_entry_safe(asconf, tmp, &asoc->addip_chunk_list, list) {
1657 list_del_init(&asconf->list);
1658 sctp_chunk_free(asconf);
1659 }
1660 }
1661
1662 /* Free asconf_ack cache */
1663 static void sctp_assoc_free_asconf_acks(struct sctp_association *asoc)
1664 {
1665 struct sctp_chunk *ack;
1666 struct sctp_chunk *tmp;
1667
1668 list_for_each_entry_safe(ack, tmp, &asoc->asconf_ack_list,
1669 transmitted_list) {
1670 list_del_init(&ack->transmitted_list);
1671 sctp_chunk_free(ack);
1672 }
1673 }
1674
1675 /* Clean up the ASCONF_ACK queue */
1676 void sctp_assoc_clean_asconf_ack_cache(const struct sctp_association *asoc)
1677 {
1678 struct sctp_chunk *ack;
1679 struct sctp_chunk *tmp;
1680
1681 /* We can remove all the entries from the queue up to
1682 * the "Peer-Sequence-Number".
1683 */
1684 list_for_each_entry_safe(ack, tmp, &asoc->asconf_ack_list,
1685 transmitted_list) {
1686 if (ack->subh.addip_hdr->serial ==
1687 htonl(asoc->peer.addip_serial))
1688 break;
1689
1690 list_del_init(&ack->transmitted_list);
1691 sctp_chunk_free(ack);
1692 }
1693 }
1694
1695 /* Find the ASCONF_ACK whose serial number matches ASCONF */
1696 struct sctp_chunk *sctp_assoc_lookup_asconf_ack(
1697 const struct sctp_association *asoc,
1698 __be32 serial)
1699 {
1700 struct sctp_chunk *ack;
1701
1702 /* Walk through the list of cached ASCONF-ACKs and find the
1703 * ack chunk whose serial number matches that of the request.
1704 */
1705 list_for_each_entry(ack, &asoc->asconf_ack_list, transmitted_list) {
1706 if (sctp_chunk_pending(ack))
1707 continue;
1708 if (ack->subh.addip_hdr->serial == serial) {
1709 sctp_chunk_hold(ack);
1710 return ack;
1711 }
1712 }
1713
1714 return NULL;
1715 }
1716
1717 void sctp_asconf_queue_teardown(struct sctp_association *asoc)
1718 {
1719 /* Free any cached ASCONF_ACK chunk. */
1720 sctp_assoc_free_asconf_acks(asoc);
1721
1722 /* Free the ASCONF queue. */
1723 sctp_assoc_free_asconf_queue(asoc);
1724
1725 /* Free any cached ASCONF chunk. */
1726 if (asoc->addip_last_asconf)
1727 sctp_chunk_free(asoc->addip_last_asconf);
1728 }
1729
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