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. */
sctp_association_init(struct sctp_association * asoc,const struct sctp_endpoint * ep,const struct sock * sk,enum sctp_scope scope,gfp_t gfp)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 if (!sctp_ulpq_init(&asoc->ulpq, asoc))
230 goto fail_init;
231
232 if (sctp_stream_init(&asoc->stream, asoc->c.sinit_num_ostreams, 0, gfp))
233 goto stream_free;
234
235 /* Initialize default path MTU. */
236 asoc->pathmtu = sp->pathmtu;
237 sctp_assoc_update_frag_point(asoc);
238
239 /* Assume that peer would support both address types unless we are
240 * told otherwise.
241 */
242 asoc->peer.ipv4_address = 1;
243 if (asoc->base.sk->sk_family == PF_INET6)
244 asoc->peer.ipv6_address = 1;
245 INIT_LIST_HEAD(&asoc->asocs);
246
247 asoc->default_stream = sp->default_stream;
248 asoc->default_ppid = sp->default_ppid;
249 asoc->default_flags = sp->default_flags;
250 asoc->default_context = sp->default_context;
251 asoc->default_timetolive = sp->default_timetolive;
252 asoc->default_rcv_context = sp->default_rcv_context;
253
254 /* AUTH related initializations */
255 INIT_LIST_HEAD(&asoc->endpoint_shared_keys);
256 if (sctp_auth_asoc_copy_shkeys(ep, asoc, gfp))
257 goto stream_free;
258
259 asoc->active_key_id = ep->active_key_id;
260 asoc->strreset_enable = ep->strreset_enable;
261
262 /* Save the hmacs and chunks list into this association */
263 if (ep->auth_hmacs_list)
264 memcpy(asoc->c.auth_hmacs, ep->auth_hmacs_list,
265 ntohs(ep->auth_hmacs_list->param_hdr.length));
266 if (ep->auth_chunk_list)
267 memcpy(asoc->c.auth_chunks, ep->auth_chunk_list,
268 ntohs(ep->auth_chunk_list->param_hdr.length));
269
270 /* Get the AUTH random number for this association */
271 p = (struct sctp_paramhdr *)asoc->c.auth_random;
272 p->type = SCTP_PARAM_RANDOM;
273 p->length = htons(sizeof(*p) + SCTP_AUTH_RANDOM_LENGTH);
274 get_random_bytes(p+1, SCTP_AUTH_RANDOM_LENGTH);
275
276 return asoc;
277
278 stream_free:
279 sctp_stream_free(&asoc->stream);
280 fail_init:
281 sock_put(asoc->base.sk);
282 sctp_endpoint_put(asoc->ep);
283 return NULL;
284 }
285
286 /* Allocate and initialize a new association */
sctp_association_new(const struct sctp_endpoint * ep,const struct sock * sk,enum sctp_scope scope,gfp_t gfp)287 struct sctp_association *sctp_association_new(const struct sctp_endpoint *ep,
288 const struct sock *sk,
289 enum sctp_scope scope, gfp_t gfp)
290 {
291 struct sctp_association *asoc;
292
293 asoc = kzalloc(sizeof(*asoc), gfp);
294 if (!asoc)
295 goto fail;
296
297 if (!sctp_association_init(asoc, ep, sk, scope, gfp))
298 goto fail_init;
299
300 SCTP_DBG_OBJCNT_INC(assoc);
301
302 pr_debug("Created asoc %p\n", asoc);
303
304 return asoc;
305
306 fail_init:
307 kfree(asoc);
308 fail:
309 return NULL;
310 }
311
312 /* Free this association if possible. There may still be users, so
313 * the actual deallocation may be delayed.
314 */
sctp_association_free(struct sctp_association * asoc)315 void sctp_association_free(struct sctp_association *asoc)
316 {
317 struct sock *sk = asoc->base.sk;
318 struct sctp_transport *transport;
319 struct list_head *pos, *temp;
320 int i;
321
322 /* Only real associations count against the endpoint, so
323 * don't bother for if this is a temporary association.
324 */
325 if (!list_empty(&asoc->asocs)) {
326 list_del(&asoc->asocs);
327
328 /* Decrement the backlog value for a TCP-style listening
329 * socket.
330 */
331 if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
332 sk_acceptq_removed(sk);
333 }
334
335 /* Mark as dead, so other users can know this structure is
336 * going away.
337 */
338 asoc->base.dead = true;
339
340 /* Dispose of any data lying around in the outqueue. */
341 sctp_outq_free(&asoc->outqueue);
342
343 /* Dispose of any pending messages for the upper layer. */
344 sctp_ulpq_free(&asoc->ulpq);
345
346 /* Dispose of any pending chunks on the inqueue. */
347 sctp_inq_free(&asoc->base.inqueue);
348
349 sctp_tsnmap_free(&asoc->peer.tsn_map);
350
351 /* Free stream information. */
352 sctp_stream_free(&asoc->stream);
353
354 if (asoc->strreset_chunk)
355 sctp_chunk_free(asoc->strreset_chunk);
356
357 /* Clean up the bound address list. */
358 sctp_bind_addr_free(&asoc->base.bind_addr);
359
360 /* Do we need to go through all of our timers and
361 * delete them? To be safe we will try to delete all, but we
362 * should be able to go through and make a guess based
363 * on our state.
364 */
365 for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i) {
366 if (del_timer(&asoc->timers[i]))
367 sctp_association_put(asoc);
368 }
369
370 /* Free peer's cached cookie. */
371 kfree(asoc->peer.cookie);
372 kfree(asoc->peer.peer_random);
373 kfree(asoc->peer.peer_chunks);
374 kfree(asoc->peer.peer_hmacs);
375
376 /* Release the transport structures. */
377 list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
378 transport = list_entry(pos, struct sctp_transport, transports);
379 list_del_rcu(pos);
380 sctp_unhash_transport(transport);
381 sctp_transport_free(transport);
382 }
383
384 asoc->peer.transport_count = 0;
385
386 sctp_asconf_queue_teardown(asoc);
387
388 /* Free pending address space being deleted */
389 kfree(asoc->asconf_addr_del_pending);
390
391 /* AUTH - Free the endpoint shared keys */
392 sctp_auth_destroy_keys(&asoc->endpoint_shared_keys);
393
394 /* AUTH - Free the association shared key */
395 sctp_auth_key_put(asoc->asoc_shared_key);
396
397 sctp_association_put(asoc);
398 }
399
400 /* Cleanup and free up an association. */
sctp_association_destroy(struct sctp_association * asoc)401 static void sctp_association_destroy(struct sctp_association *asoc)
402 {
403 if (unlikely(!asoc->base.dead)) {
404 WARN(1, "Attempt to destroy undead association %p!\n", asoc);
405 return;
406 }
407
408 sctp_endpoint_put(asoc->ep);
409 sock_put(asoc->base.sk);
410
411 if (asoc->assoc_id != 0) {
412 spin_lock_bh(&sctp_assocs_id_lock);
413 idr_remove(&sctp_assocs_id, asoc->assoc_id);
414 spin_unlock_bh(&sctp_assocs_id_lock);
415 }
416
417 WARN_ON(atomic_read(&asoc->rmem_alloc));
418
419 kfree_rcu(asoc, rcu);
420 SCTP_DBG_OBJCNT_DEC(assoc);
421 }
422
423 /* Change the primary destination address for the peer. */
sctp_assoc_set_primary(struct sctp_association * asoc,struct sctp_transport * transport)424 void sctp_assoc_set_primary(struct sctp_association *asoc,
425 struct sctp_transport *transport)
426 {
427 int changeover = 0;
428
429 /* it's a changeover only if we already have a primary path
430 * that we are changing
431 */
432 if (asoc->peer.primary_path != NULL &&
433 asoc->peer.primary_path != transport)
434 changeover = 1 ;
435
436 asoc->peer.primary_path = transport;
437 sctp_ulpevent_notify_peer_addr_change(transport,
438 SCTP_ADDR_MADE_PRIM, 0);
439
440 /* Set a default msg_name for events. */
441 memcpy(&asoc->peer.primary_addr, &transport->ipaddr,
442 sizeof(union sctp_addr));
443
444 /* If the primary path is changing, assume that the
445 * user wants to use this new path.
446 */
447 if ((transport->state == SCTP_ACTIVE) ||
448 (transport->state == SCTP_UNKNOWN))
449 asoc->peer.active_path = transport;
450
451 /*
452 * SFR-CACC algorithm:
453 * Upon the receipt of a request to change the primary
454 * destination address, on the data structure for the new
455 * primary destination, the sender MUST do the following:
456 *
457 * 1) If CHANGEOVER_ACTIVE is set, then there was a switch
458 * to this destination address earlier. The sender MUST set
459 * CYCLING_CHANGEOVER to indicate that this switch is a
460 * double switch to the same destination address.
461 *
462 * Really, only bother is we have data queued or outstanding on
463 * the association.
464 */
465 if (!asoc->outqueue.outstanding_bytes && !asoc->outqueue.out_qlen)
466 return;
467
468 if (transport->cacc.changeover_active)
469 transport->cacc.cycling_changeover = changeover;
470
471 /* 2) The sender MUST set CHANGEOVER_ACTIVE to indicate that
472 * a changeover has occurred.
473 */
474 transport->cacc.changeover_active = changeover;
475
476 /* 3) The sender MUST store the next TSN to be sent in
477 * next_tsn_at_change.
478 */
479 transport->cacc.next_tsn_at_change = asoc->next_tsn;
480 }
481
482 /* Remove a transport from an association. */
sctp_assoc_rm_peer(struct sctp_association * asoc,struct sctp_transport * peer)483 void sctp_assoc_rm_peer(struct sctp_association *asoc,
484 struct sctp_transport *peer)
485 {
486 struct sctp_transport *transport;
487 struct list_head *pos;
488 struct sctp_chunk *ch;
489
490 pr_debug("%s: association:%p addr:%pISpc\n",
491 __func__, asoc, &peer->ipaddr.sa);
492
493 /* If we are to remove the current retran_path, update it
494 * to the next peer before removing this peer from the list.
495 */
496 if (asoc->peer.retran_path == peer)
497 sctp_assoc_update_retran_path(asoc);
498
499 /* Remove this peer from the list. */
500 list_del_rcu(&peer->transports);
501 /* Remove this peer from the transport hashtable */
502 sctp_unhash_transport(peer);
503
504 /* Get the first transport of asoc. */
505 pos = asoc->peer.transport_addr_list.next;
506 transport = list_entry(pos, struct sctp_transport, transports);
507
508 /* Update any entries that match the peer to be deleted. */
509 if (asoc->peer.primary_path == peer)
510 sctp_assoc_set_primary(asoc, transport);
511 if (asoc->peer.active_path == peer)
512 asoc->peer.active_path = transport;
513 if (asoc->peer.retran_path == peer)
514 asoc->peer.retran_path = transport;
515 if (asoc->peer.last_data_from == peer)
516 asoc->peer.last_data_from = transport;
517
518 if (asoc->strreset_chunk &&
519 asoc->strreset_chunk->transport == peer) {
520 asoc->strreset_chunk->transport = transport;
521 sctp_transport_reset_reconf_timer(transport);
522 }
523
524 /* If we remove the transport an INIT was last sent to, set it to
525 * NULL. Combined with the update of the retran path above, this
526 * will cause the next INIT to be sent to the next available
527 * transport, maintaining the cycle.
528 */
529 if (asoc->init_last_sent_to == peer)
530 asoc->init_last_sent_to = NULL;
531
532 /* If we remove the transport an SHUTDOWN was last sent to, set it
533 * to NULL. Combined with the update of the retran path above, this
534 * will cause the next SHUTDOWN to be sent to the next available
535 * transport, maintaining the cycle.
536 */
537 if (asoc->shutdown_last_sent_to == peer)
538 asoc->shutdown_last_sent_to = NULL;
539
540 /* If we remove the transport an ASCONF was last sent to, set it to
541 * NULL.
542 */
543 if (asoc->addip_last_asconf &&
544 asoc->addip_last_asconf->transport == peer)
545 asoc->addip_last_asconf->transport = NULL;
546
547 /* If we have something on the transmitted list, we have to
548 * save it off. The best place is the active path.
549 */
550 if (!list_empty(&peer->transmitted)) {
551 struct sctp_transport *active = asoc->peer.active_path;
552
553 /* Reset the transport of each chunk on this list */
554 list_for_each_entry(ch, &peer->transmitted,
555 transmitted_list) {
556 ch->transport = NULL;
557 ch->rtt_in_progress = 0;
558 }
559
560 list_splice_tail_init(&peer->transmitted,
561 &active->transmitted);
562
563 /* Start a T3 timer here in case it wasn't running so
564 * that these migrated packets have a chance to get
565 * retransmitted.
566 */
567 if (!timer_pending(&active->T3_rtx_timer))
568 if (!mod_timer(&active->T3_rtx_timer,
569 jiffies + active->rto))
570 sctp_transport_hold(active);
571 }
572
573 list_for_each_entry(ch, &asoc->outqueue.out_chunk_list, list)
574 if (ch->transport == peer)
575 ch->transport = NULL;
576
577 asoc->peer.transport_count--;
578
579 sctp_ulpevent_notify_peer_addr_change(peer, SCTP_ADDR_REMOVED, 0);
580 sctp_transport_free(peer);
581 }
582
583 /* Add a transport address to an association. */
sctp_assoc_add_peer(struct sctp_association * asoc,const union sctp_addr * addr,const gfp_t gfp,const int peer_state)584 struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc,
585 const union sctp_addr *addr,
586 const gfp_t gfp,
587 const int peer_state)
588 {
589 struct sctp_transport *peer;
590 struct sctp_sock *sp;
591 unsigned short port;
592
593 sp = sctp_sk(asoc->base.sk);
594
595 /* AF_INET and AF_INET6 share common port field. */
596 port = ntohs(addr->v4.sin_port);
597
598 pr_debug("%s: association:%p addr:%pISpc state:%d\n", __func__,
599 asoc, &addr->sa, peer_state);
600
601 /* Set the port if it has not been set yet. */
602 if (0 == asoc->peer.port)
603 asoc->peer.port = port;
604
605 /* Check to see if this is a duplicate. */
606 peer = sctp_assoc_lookup_paddr(asoc, addr);
607 if (peer) {
608 /* An UNKNOWN state is only set on transports added by
609 * user in sctp_connectx() call. Such transports should be
610 * considered CONFIRMED per RFC 4960, Section 5.4.
611 */
612 if (peer->state == SCTP_UNKNOWN) {
613 peer->state = SCTP_ACTIVE;
614 }
615 return peer;
616 }
617
618 peer = sctp_transport_new(asoc->base.net, addr, gfp);
619 if (!peer)
620 return NULL;
621
622 sctp_transport_set_owner(peer, asoc);
623
624 /* Initialize the peer's heartbeat interval based on the
625 * association configured value.
626 */
627 peer->hbinterval = asoc->hbinterval;
628 peer->probe_interval = asoc->probe_interval;
629
630 peer->encap_port = asoc->encap_port;
631
632 /* Set the path max_retrans. */
633 peer->pathmaxrxt = asoc->pathmaxrxt;
634
635 /* And the partial failure retrans threshold */
636 peer->pf_retrans = asoc->pf_retrans;
637 /* And the primary path switchover retrans threshold */
638 peer->ps_retrans = asoc->ps_retrans;
639
640 /* Initialize the peer's SACK delay timeout based on the
641 * association configured value.
642 */
643 peer->sackdelay = asoc->sackdelay;
644 peer->sackfreq = asoc->sackfreq;
645
646 if (addr->sa.sa_family == AF_INET6) {
647 __be32 info = addr->v6.sin6_flowinfo;
648
649 if (info) {
650 peer->flowlabel = ntohl(info & IPV6_FLOWLABEL_MASK);
651 peer->flowlabel |= SCTP_FLOWLABEL_SET_MASK;
652 } else {
653 peer->flowlabel = asoc->flowlabel;
654 }
655 }
656 peer->dscp = asoc->dscp;
657
658 /* Enable/disable heartbeat, SACK delay, and path MTU discovery
659 * based on association setting.
660 */
661 peer->param_flags = asoc->param_flags;
662
663 /* Initialize the pmtu of the transport. */
664 sctp_transport_route(peer, NULL, sp);
665
666 /* If this is the first transport addr on this association,
667 * initialize the association PMTU to the peer's PMTU.
668 * If not and the current association PMTU is higher than the new
669 * peer's PMTU, reset the association PMTU to the new peer's PMTU.
670 */
671 sctp_assoc_set_pmtu(asoc, asoc->pathmtu ?
672 min_t(int, peer->pathmtu, asoc->pathmtu) :
673 peer->pathmtu);
674
675 peer->pmtu_pending = 0;
676
677 /* The asoc->peer.port might not be meaningful yet, but
678 * initialize the packet structure anyway.
679 */
680 sctp_packet_init(&peer->packet, peer, asoc->base.bind_addr.port,
681 asoc->peer.port);
682
683 /* 7.2.1 Slow-Start
684 *
685 * o The initial cwnd before DATA transmission or after a sufficiently
686 * long idle period MUST be set to
687 * min(4*MTU, max(2*MTU, 4380 bytes))
688 *
689 * o The initial value of ssthresh MAY be arbitrarily high
690 * (for example, implementations MAY use the size of the
691 * receiver advertised window).
692 */
693 peer->cwnd = min(4*asoc->pathmtu, max_t(__u32, 2*asoc->pathmtu, 4380));
694
695 /* At this point, we may not have the receiver's advertised window,
696 * so initialize ssthresh to the default value and it will be set
697 * later when we process the INIT.
698 */
699 peer->ssthresh = SCTP_DEFAULT_MAXWINDOW;
700
701 peer->partial_bytes_acked = 0;
702 peer->flight_size = 0;
703 peer->burst_limited = 0;
704
705 /* Set the transport's RTO.initial value */
706 peer->rto = asoc->rto_initial;
707 sctp_max_rto(asoc, peer);
708
709 /* Set the peer's active state. */
710 peer->state = peer_state;
711
712 /* Add this peer into the transport hashtable */
713 if (sctp_hash_transport(peer)) {
714 sctp_transport_free(peer);
715 return NULL;
716 }
717
718 sctp_transport_pl_reset(peer);
719
720 /* Attach the remote transport to our asoc. */
721 list_add_tail_rcu(&peer->transports, &asoc->peer.transport_addr_list);
722 asoc->peer.transport_count++;
723
724 sctp_ulpevent_notify_peer_addr_change(peer, SCTP_ADDR_ADDED, 0);
725
726 /* If we do not yet have a primary path, set one. */
727 if (!asoc->peer.primary_path) {
728 sctp_assoc_set_primary(asoc, peer);
729 asoc->peer.retran_path = peer;
730 }
731
732 if (asoc->peer.active_path == asoc->peer.retran_path &&
733 peer->state != SCTP_UNCONFIRMED) {
734 asoc->peer.retran_path = peer;
735 }
736
737 return peer;
738 }
739
740 /* Delete a transport address from an association. */
sctp_assoc_del_peer(struct sctp_association * asoc,const union sctp_addr * addr)741 void sctp_assoc_del_peer(struct sctp_association *asoc,
742 const union sctp_addr *addr)
743 {
744 struct list_head *pos;
745 struct list_head *temp;
746 struct sctp_transport *transport;
747
748 list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
749 transport = list_entry(pos, struct sctp_transport, transports);
750 if (sctp_cmp_addr_exact(addr, &transport->ipaddr)) {
751 /* Do book keeping for removing the peer and free it. */
752 sctp_assoc_rm_peer(asoc, transport);
753 break;
754 }
755 }
756 }
757
758 /* Lookup a transport by address. */
sctp_assoc_lookup_paddr(const struct sctp_association * asoc,const union sctp_addr * address)759 struct sctp_transport *sctp_assoc_lookup_paddr(
760 const struct sctp_association *asoc,
761 const union sctp_addr *address)
762 {
763 struct sctp_transport *t;
764
765 /* Cycle through all transports searching for a peer address. */
766
767 list_for_each_entry(t, &asoc->peer.transport_addr_list,
768 transports) {
769 if (sctp_cmp_addr_exact(address, &t->ipaddr))
770 return t;
771 }
772
773 return NULL;
774 }
775
776 /* Remove all transports except a give one */
sctp_assoc_del_nonprimary_peers(struct sctp_association * asoc,struct sctp_transport * primary)777 void sctp_assoc_del_nonprimary_peers(struct sctp_association *asoc,
778 struct sctp_transport *primary)
779 {
780 struct sctp_transport *temp;
781 struct sctp_transport *t;
782
783 list_for_each_entry_safe(t, temp, &asoc->peer.transport_addr_list,
784 transports) {
785 /* if the current transport is not the primary one, delete it */
786 if (t != primary)
787 sctp_assoc_rm_peer(asoc, t);
788 }
789 }
790
791 /* Engage in transport control operations.
792 * Mark the transport up or down and send a notification to the user.
793 * Select and update the new active and retran paths.
794 */
sctp_assoc_control_transport(struct sctp_association * asoc,struct sctp_transport * transport,enum sctp_transport_cmd command,sctp_sn_error_t error)795 void sctp_assoc_control_transport(struct sctp_association *asoc,
796 struct sctp_transport *transport,
797 enum sctp_transport_cmd command,
798 sctp_sn_error_t error)
799 {
800 int spc_state = SCTP_ADDR_AVAILABLE;
801 bool ulp_notify = true;
802
803 /* Record the transition on the transport. */
804 switch (command) {
805 case SCTP_TRANSPORT_UP:
806 /* If we are moving from UNCONFIRMED state due
807 * to heartbeat success, report the SCTP_ADDR_CONFIRMED
808 * state to the user, otherwise report SCTP_ADDR_AVAILABLE.
809 */
810 if (transport->state == SCTP_PF &&
811 asoc->pf_expose != SCTP_PF_EXPOSE_ENABLE)
812 ulp_notify = false;
813 else if (transport->state == SCTP_UNCONFIRMED &&
814 error == SCTP_HEARTBEAT_SUCCESS)
815 spc_state = SCTP_ADDR_CONFIRMED;
816
817 transport->state = SCTP_ACTIVE;
818 sctp_transport_pl_reset(transport);
819 break;
820
821 case SCTP_TRANSPORT_DOWN:
822 /* If the transport was never confirmed, do not transition it
823 * to inactive state. Also, release the cached route since
824 * there may be a better route next time.
825 */
826 if (transport->state != SCTP_UNCONFIRMED) {
827 transport->state = SCTP_INACTIVE;
828 sctp_transport_pl_reset(transport);
829 spc_state = SCTP_ADDR_UNREACHABLE;
830 } else {
831 sctp_transport_dst_release(transport);
832 ulp_notify = false;
833 }
834 break;
835
836 case SCTP_TRANSPORT_PF:
837 transport->state = SCTP_PF;
838 if (asoc->pf_expose != SCTP_PF_EXPOSE_ENABLE)
839 ulp_notify = false;
840 else
841 spc_state = SCTP_ADDR_POTENTIALLY_FAILED;
842 break;
843
844 default:
845 return;
846 }
847
848 /* Generate and send a SCTP_PEER_ADDR_CHANGE notification
849 * to the user.
850 */
851 if (ulp_notify)
852 sctp_ulpevent_notify_peer_addr_change(transport,
853 spc_state, error);
854
855 /* Select new active and retran paths. */
856 sctp_select_active_and_retran_path(asoc);
857 }
858
859 /* Hold a reference to an association. */
sctp_association_hold(struct sctp_association * asoc)860 void sctp_association_hold(struct sctp_association *asoc)
861 {
862 refcount_inc(&asoc->base.refcnt);
863 }
864
865 /* Release a reference to an association and cleanup
866 * if there are no more references.
867 */
sctp_association_put(struct sctp_association * asoc)868 void sctp_association_put(struct sctp_association *asoc)
869 {
870 if (refcount_dec_and_test(&asoc->base.refcnt))
871 sctp_association_destroy(asoc);
872 }
873
874 /* Allocate the next TSN, Transmission Sequence Number, for the given
875 * association.
876 */
sctp_association_get_next_tsn(struct sctp_association * asoc)877 __u32 sctp_association_get_next_tsn(struct sctp_association *asoc)
878 {
879 /* From Section 1.6 Serial Number Arithmetic:
880 * Transmission Sequence Numbers wrap around when they reach
881 * 2**32 - 1. That is, the next TSN a DATA chunk MUST use
882 * after transmitting TSN = 2*32 - 1 is TSN = 0.
883 */
884 __u32 retval = asoc->next_tsn;
885 asoc->next_tsn++;
886 asoc->unack_data++;
887
888 return retval;
889 }
890
891 /* Compare two addresses to see if they match. Wildcard addresses
892 * only match themselves.
893 */
sctp_cmp_addr_exact(const union sctp_addr * ss1,const union sctp_addr * ss2)894 int sctp_cmp_addr_exact(const union sctp_addr *ss1,
895 const union sctp_addr *ss2)
896 {
897 struct sctp_af *af;
898
899 af = sctp_get_af_specific(ss1->sa.sa_family);
900 if (unlikely(!af))
901 return 0;
902
903 return af->cmp_addr(ss1, ss2);
904 }
905
906 /* Return an ecne chunk to get prepended to a packet.
907 * Note: We are sly and return a shared, prealloced chunk. FIXME:
908 * No we don't, but we could/should.
909 */
sctp_get_ecne_prepend(struct sctp_association * asoc)910 struct sctp_chunk *sctp_get_ecne_prepend(struct sctp_association *asoc)
911 {
912 if (!asoc->need_ecne)
913 return NULL;
914
915 /* Send ECNE if needed.
916 * Not being able to allocate a chunk here is not deadly.
917 */
918 return sctp_make_ecne(asoc, asoc->last_ecne_tsn);
919 }
920
921 /*
922 * Find which transport this TSN was sent on.
923 */
sctp_assoc_lookup_tsn(struct sctp_association * asoc,__u32 tsn)924 struct sctp_transport *sctp_assoc_lookup_tsn(struct sctp_association *asoc,
925 __u32 tsn)
926 {
927 struct sctp_transport *active;
928 struct sctp_transport *match;
929 struct sctp_transport *transport;
930 struct sctp_chunk *chunk;
931 __be32 key = htonl(tsn);
932
933 match = NULL;
934
935 /*
936 * FIXME: In general, find a more efficient data structure for
937 * searching.
938 */
939
940 /*
941 * The general strategy is to search each transport's transmitted
942 * list. Return which transport this TSN lives on.
943 *
944 * Let's be hopeful and check the active_path first.
945 * Another optimization would be to know if there is only one
946 * outbound path and not have to look for the TSN at all.
947 *
948 */
949
950 active = asoc->peer.active_path;
951
952 list_for_each_entry(chunk, &active->transmitted,
953 transmitted_list) {
954
955 if (key == chunk->subh.data_hdr->tsn) {
956 match = active;
957 goto out;
958 }
959 }
960
961 /* If not found, go search all the other transports. */
962 list_for_each_entry(transport, &asoc->peer.transport_addr_list,
963 transports) {
964
965 if (transport == active)
966 continue;
967 list_for_each_entry(chunk, &transport->transmitted,
968 transmitted_list) {
969 if (key == chunk->subh.data_hdr->tsn) {
970 match = transport;
971 goto out;
972 }
973 }
974 }
975 out:
976 return match;
977 }
978
979 /* Do delayed input processing. This is scheduled by sctp_rcv(). */
sctp_assoc_bh_rcv(struct work_struct * work)980 static void sctp_assoc_bh_rcv(struct work_struct *work)
981 {
982 struct sctp_association *asoc =
983 container_of(work, struct sctp_association,
984 base.inqueue.immediate);
985 struct net *net = asoc->base.net;
986 union sctp_subtype subtype;
987 struct sctp_endpoint *ep;
988 struct sctp_chunk *chunk;
989 struct sctp_inq *inqueue;
990 int first_time = 1; /* is this the first time through the loop */
991 int error = 0;
992 int state;
993
994 /* The association should be held so we should be safe. */
995 ep = asoc->ep;
996
997 inqueue = &asoc->base.inqueue;
998 sctp_association_hold(asoc);
999 while (NULL != (chunk = sctp_inq_pop(inqueue))) {
1000 state = asoc->state;
1001 subtype = SCTP_ST_CHUNK(chunk->chunk_hdr->type);
1002
1003 /* If the first chunk in the packet is AUTH, do special
1004 * processing specified in Section 6.3 of SCTP-AUTH spec
1005 */
1006 if (first_time && subtype.chunk == SCTP_CID_AUTH) {
1007 struct sctp_chunkhdr *next_hdr;
1008
1009 next_hdr = sctp_inq_peek(inqueue);
1010 if (!next_hdr)
1011 goto normal;
1012
1013 /* If the next chunk is COOKIE-ECHO, skip the AUTH
1014 * chunk while saving a pointer to it so we can do
1015 * Authentication later (during cookie-echo
1016 * processing).
1017 */
1018 if (next_hdr->type == SCTP_CID_COOKIE_ECHO) {
1019 chunk->auth_chunk = skb_clone(chunk->skb,
1020 GFP_ATOMIC);
1021 chunk->auth = 1;
1022 continue;
1023 }
1024 }
1025
1026 normal:
1027 /* SCTP-AUTH, Section 6.3:
1028 * The receiver has a list of chunk types which it expects
1029 * to be received only after an AUTH-chunk. This list has
1030 * been sent to the peer during the association setup. It
1031 * MUST silently discard these chunks if they are not placed
1032 * after an AUTH chunk in the packet.
1033 */
1034 if (sctp_auth_recv_cid(subtype.chunk, asoc) && !chunk->auth)
1035 continue;
1036
1037 /* Remember where the last DATA chunk came from so we
1038 * know where to send the SACK.
1039 */
1040 if (sctp_chunk_is_data(chunk))
1041 asoc->peer.last_data_from = chunk->transport;
1042 else {
1043 SCTP_INC_STATS(net, SCTP_MIB_INCTRLCHUNKS);
1044 asoc->stats.ictrlchunks++;
1045 if (chunk->chunk_hdr->type == SCTP_CID_SACK)
1046 asoc->stats.isacks++;
1047 }
1048
1049 if (chunk->transport)
1050 chunk->transport->last_time_heard = ktime_get();
1051
1052 /* Run through the state machine. */
1053 error = sctp_do_sm(net, SCTP_EVENT_T_CHUNK, subtype,
1054 state, ep, asoc, chunk, GFP_ATOMIC);
1055
1056 /* Check to see if the association is freed in response to
1057 * the incoming chunk. If so, get out of the while loop.
1058 */
1059 if (asoc->base.dead)
1060 break;
1061
1062 /* If there is an error on chunk, discard this packet. */
1063 if (error && chunk)
1064 chunk->pdiscard = 1;
1065
1066 if (first_time)
1067 first_time = 0;
1068 }
1069 sctp_association_put(asoc);
1070 }
1071
1072 /* This routine moves an association from its old sk to a new sk. */
sctp_assoc_migrate(struct sctp_association * assoc,struct sock * newsk)1073 void sctp_assoc_migrate(struct sctp_association *assoc, struct sock *newsk)
1074 {
1075 struct sctp_sock *newsp = sctp_sk(newsk);
1076 struct sock *oldsk = assoc->base.sk;
1077
1078 /* Delete the association from the old endpoint's list of
1079 * associations.
1080 */
1081 list_del_init(&assoc->asocs);
1082
1083 /* Decrement the backlog value for a TCP-style socket. */
1084 if (sctp_style(oldsk, TCP))
1085 sk_acceptq_removed(oldsk);
1086
1087 /* Release references to the old endpoint and the sock. */
1088 sctp_endpoint_put(assoc->ep);
1089 sock_put(assoc->base.sk);
1090
1091 /* Get a reference to the new endpoint. */
1092 assoc->ep = newsp->ep;
1093 sctp_endpoint_hold(assoc->ep);
1094
1095 /* Get a reference to the new sock. */
1096 assoc->base.sk = newsk;
1097 sock_hold(assoc->base.sk);
1098
1099 /* Add the association to the new endpoint's list of associations. */
1100 sctp_endpoint_add_asoc(newsp->ep, assoc);
1101 }
1102
1103 /* Update an association (possibly from unexpected COOKIE-ECHO processing). */
sctp_assoc_update(struct sctp_association * asoc,struct sctp_association * new)1104 int sctp_assoc_update(struct sctp_association *asoc,
1105 struct sctp_association *new)
1106 {
1107 struct sctp_transport *trans;
1108 struct list_head *pos, *temp;
1109
1110 /* Copy in new parameters of peer. */
1111 asoc->c = new->c;
1112 asoc->peer.rwnd = new->peer.rwnd;
1113 asoc->peer.sack_needed = new->peer.sack_needed;
1114 asoc->peer.auth_capable = new->peer.auth_capable;
1115 asoc->peer.i = new->peer.i;
1116
1117 if (!sctp_tsnmap_init(&asoc->peer.tsn_map, SCTP_TSN_MAP_INITIAL,
1118 asoc->peer.i.initial_tsn, GFP_ATOMIC))
1119 return -ENOMEM;
1120
1121 /* Remove any peer addresses not present in the new association. */
1122 list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
1123 trans = list_entry(pos, struct sctp_transport, transports);
1124 if (!sctp_assoc_lookup_paddr(new, &trans->ipaddr)) {
1125 sctp_assoc_rm_peer(asoc, trans);
1126 continue;
1127 }
1128
1129 if (asoc->state >= SCTP_STATE_ESTABLISHED)
1130 sctp_transport_reset(trans);
1131 }
1132
1133 /* If the case is A (association restart), use
1134 * initial_tsn as next_tsn. If the case is B, use
1135 * current next_tsn in case data sent to peer
1136 * has been discarded and needs retransmission.
1137 */
1138 if (asoc->state >= SCTP_STATE_ESTABLISHED) {
1139 asoc->next_tsn = new->next_tsn;
1140 asoc->ctsn_ack_point = new->ctsn_ack_point;
1141 asoc->adv_peer_ack_point = new->adv_peer_ack_point;
1142
1143 /* Reinitialize SSN for both local streams
1144 * and peer's streams.
1145 */
1146 sctp_stream_clear(&asoc->stream);
1147
1148 /* Flush the ULP reassembly and ordered queue.
1149 * Any data there will now be stale and will
1150 * cause problems.
1151 */
1152 sctp_ulpq_flush(&asoc->ulpq);
1153
1154 /* reset the overall association error count so
1155 * that the restarted association doesn't get torn
1156 * down on the next retransmission timer.
1157 */
1158 asoc->overall_error_count = 0;
1159
1160 } else {
1161 /* Add any peer addresses from the new association. */
1162 list_for_each_entry(trans, &new->peer.transport_addr_list,
1163 transports)
1164 if (!sctp_assoc_lookup_paddr(asoc, &trans->ipaddr) &&
1165 !sctp_assoc_add_peer(asoc, &trans->ipaddr,
1166 GFP_ATOMIC, trans->state))
1167 return -ENOMEM;
1168
1169 asoc->ctsn_ack_point = asoc->next_tsn - 1;
1170 asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
1171
1172 if (sctp_state(asoc, COOKIE_WAIT))
1173 sctp_stream_update(&asoc->stream, &new->stream);
1174
1175 /* get a new assoc id if we don't have one yet. */
1176 if (sctp_assoc_set_id(asoc, GFP_ATOMIC))
1177 return -ENOMEM;
1178 }
1179
1180 /* SCTP-AUTH: Save the peer parameters from the new associations
1181 * and also move the association shared keys over
1182 */
1183 kfree(asoc->peer.peer_random);
1184 asoc->peer.peer_random = new->peer.peer_random;
1185 new->peer.peer_random = NULL;
1186
1187 kfree(asoc->peer.peer_chunks);
1188 asoc->peer.peer_chunks = new->peer.peer_chunks;
1189 new->peer.peer_chunks = NULL;
1190
1191 kfree(asoc->peer.peer_hmacs);
1192 asoc->peer.peer_hmacs = new->peer.peer_hmacs;
1193 new->peer.peer_hmacs = NULL;
1194
1195 return sctp_auth_asoc_init_active_key(asoc, GFP_ATOMIC);
1196 }
1197
1198 /* Update the retran path for sending a retransmitted packet.
1199 * See also RFC4960, 6.4. Multi-Homed SCTP Endpoints:
1200 *
1201 * When there is outbound data to send and the primary path
1202 * becomes inactive (e.g., due to failures), or where the
1203 * SCTP user explicitly requests to send data to an
1204 * inactive destination transport address, before reporting
1205 * an error to its ULP, the SCTP endpoint should try to send
1206 * the data to an alternate active destination transport
1207 * address if one exists.
1208 *
1209 * When retransmitting data that timed out, if the endpoint
1210 * is multihomed, it should consider each source-destination
1211 * address pair in its retransmission selection policy.
1212 * When retransmitting timed-out data, the endpoint should
1213 * attempt to pick the most divergent source-destination
1214 * pair from the original source-destination pair to which
1215 * the packet was transmitted.
1216 *
1217 * Note: Rules for picking the most divergent source-destination
1218 * pair are an implementation decision and are not specified
1219 * within this document.
1220 *
1221 * Our basic strategy is to round-robin transports in priorities
1222 * according to sctp_trans_score() e.g., if no such
1223 * transport with state SCTP_ACTIVE exists, round-robin through
1224 * SCTP_UNKNOWN, etc. You get the picture.
1225 */
sctp_trans_score(const struct sctp_transport * trans)1226 static u8 sctp_trans_score(const struct sctp_transport *trans)
1227 {
1228 switch (trans->state) {
1229 case SCTP_ACTIVE:
1230 return 3; /* best case */
1231 case SCTP_UNKNOWN:
1232 return 2;
1233 case SCTP_PF:
1234 return 1;
1235 default: /* case SCTP_INACTIVE */
1236 return 0; /* worst case */
1237 }
1238 }
1239
sctp_trans_elect_tie(struct sctp_transport * trans1,struct sctp_transport * trans2)1240 static struct sctp_transport *sctp_trans_elect_tie(struct sctp_transport *trans1,
1241 struct sctp_transport *trans2)
1242 {
1243 if (trans1->error_count > trans2->error_count) {
1244 return trans2;
1245 } else if (trans1->error_count == trans2->error_count &&
1246 ktime_after(trans2->last_time_heard,
1247 trans1->last_time_heard)) {
1248 return trans2;
1249 } else {
1250 return trans1;
1251 }
1252 }
1253
sctp_trans_elect_best(struct sctp_transport * curr,struct sctp_transport * best)1254 static struct sctp_transport *sctp_trans_elect_best(struct sctp_transport *curr,
1255 struct sctp_transport *best)
1256 {
1257 u8 score_curr, score_best;
1258
1259 if (best == NULL || curr == best)
1260 return curr;
1261
1262 score_curr = sctp_trans_score(curr);
1263 score_best = sctp_trans_score(best);
1264
1265 /* First, try a score-based selection if both transport states
1266 * differ. If we're in a tie, lets try to make a more clever
1267 * decision here based on error counts and last time heard.
1268 */
1269 if (score_curr > score_best)
1270 return curr;
1271 else if (score_curr == score_best)
1272 return sctp_trans_elect_tie(best, curr);
1273 else
1274 return best;
1275 }
1276
sctp_assoc_update_retran_path(struct sctp_association * asoc)1277 void sctp_assoc_update_retran_path(struct sctp_association *asoc)
1278 {
1279 struct sctp_transport *trans = asoc->peer.retran_path;
1280 struct sctp_transport *trans_next = NULL;
1281
1282 /* We're done as we only have the one and only path. */
1283 if (asoc->peer.transport_count == 1)
1284 return;
1285 /* If active_path and retran_path are the same and active,
1286 * then this is the only active path. Use it.
1287 */
1288 if (asoc->peer.active_path == asoc->peer.retran_path &&
1289 asoc->peer.active_path->state == SCTP_ACTIVE)
1290 return;
1291
1292 /* Iterate from retran_path's successor back to retran_path. */
1293 for (trans = list_next_entry(trans, transports); 1;
1294 trans = list_next_entry(trans, transports)) {
1295 /* Manually skip the head element. */
1296 if (&trans->transports == &asoc->peer.transport_addr_list)
1297 continue;
1298 if (trans->state == SCTP_UNCONFIRMED)
1299 continue;
1300 trans_next = sctp_trans_elect_best(trans, trans_next);
1301 /* Active is good enough for immediate return. */
1302 if (trans_next->state == SCTP_ACTIVE)
1303 break;
1304 /* We've reached the end, time to update path. */
1305 if (trans == asoc->peer.retran_path)
1306 break;
1307 }
1308
1309 asoc->peer.retran_path = trans_next;
1310
1311 pr_debug("%s: association:%p updated new path to addr:%pISpc\n",
1312 __func__, asoc, &asoc->peer.retran_path->ipaddr.sa);
1313 }
1314
sctp_select_active_and_retran_path(struct sctp_association * asoc)1315 static void sctp_select_active_and_retran_path(struct sctp_association *asoc)
1316 {
1317 struct sctp_transport *trans, *trans_pri = NULL, *trans_sec = NULL;
1318 struct sctp_transport *trans_pf = NULL;
1319
1320 /* Look for the two most recently used active transports. */
1321 list_for_each_entry(trans, &asoc->peer.transport_addr_list,
1322 transports) {
1323 /* Skip uninteresting transports. */
1324 if (trans->state == SCTP_INACTIVE ||
1325 trans->state == SCTP_UNCONFIRMED)
1326 continue;
1327 /* Keep track of the best PF transport from our
1328 * list in case we don't find an active one.
1329 */
1330 if (trans->state == SCTP_PF) {
1331 trans_pf = sctp_trans_elect_best(trans, trans_pf);
1332 continue;
1333 }
1334 /* For active transports, pick the most recent ones. */
1335 if (trans_pri == NULL ||
1336 ktime_after(trans->last_time_heard,
1337 trans_pri->last_time_heard)) {
1338 trans_sec = trans_pri;
1339 trans_pri = trans;
1340 } else if (trans_sec == NULL ||
1341 ktime_after(trans->last_time_heard,
1342 trans_sec->last_time_heard)) {
1343 trans_sec = trans;
1344 }
1345 }
1346
1347 /* RFC 2960 6.4 Multi-Homed SCTP Endpoints
1348 *
1349 * By default, an endpoint should always transmit to the primary
1350 * path, unless the SCTP user explicitly specifies the
1351 * destination transport address (and possibly source transport
1352 * address) to use. [If the primary is active but not most recent,
1353 * bump the most recently used transport.]
1354 */
1355 if ((asoc->peer.primary_path->state == SCTP_ACTIVE ||
1356 asoc->peer.primary_path->state == SCTP_UNKNOWN) &&
1357 asoc->peer.primary_path != trans_pri) {
1358 trans_sec = trans_pri;
1359 trans_pri = asoc->peer.primary_path;
1360 }
1361
1362 /* We did not find anything useful for a possible retransmission
1363 * path; either primary path that we found is the same as
1364 * the current one, or we didn't generally find an active one.
1365 */
1366 if (trans_sec == NULL)
1367 trans_sec = trans_pri;
1368
1369 /* If we failed to find a usable transport, just camp on the
1370 * active or pick a PF iff it's the better choice.
1371 */
1372 if (trans_pri == NULL) {
1373 trans_pri = sctp_trans_elect_best(asoc->peer.active_path, trans_pf);
1374 trans_sec = trans_pri;
1375 }
1376
1377 /* Set the active and retran transports. */
1378 asoc->peer.active_path = trans_pri;
1379 asoc->peer.retran_path = trans_sec;
1380 }
1381
1382 struct sctp_transport *
sctp_assoc_choose_alter_transport(struct sctp_association * asoc,struct sctp_transport * last_sent_to)1383 sctp_assoc_choose_alter_transport(struct sctp_association *asoc,
1384 struct sctp_transport *last_sent_to)
1385 {
1386 /* If this is the first time packet is sent, use the active path,
1387 * else use the retran path. If the last packet was sent over the
1388 * retran path, update the retran path and use it.
1389 */
1390 if (last_sent_to == NULL) {
1391 return asoc->peer.active_path;
1392 } else {
1393 if (last_sent_to == asoc->peer.retran_path)
1394 sctp_assoc_update_retran_path(asoc);
1395
1396 return asoc->peer.retran_path;
1397 }
1398 }
1399
sctp_assoc_update_frag_point(struct sctp_association * asoc)1400 void sctp_assoc_update_frag_point(struct sctp_association *asoc)
1401 {
1402 int frag = sctp_mtu_payload(sctp_sk(asoc->base.sk), asoc->pathmtu,
1403 sctp_datachk_len(&asoc->stream));
1404
1405 if (asoc->user_frag)
1406 frag = min_t(int, frag, asoc->user_frag);
1407
1408 frag = min_t(int, frag, SCTP_MAX_CHUNK_LEN -
1409 sctp_datachk_len(&asoc->stream));
1410
1411 asoc->frag_point = SCTP_TRUNC4(frag);
1412 }
1413
sctp_assoc_set_pmtu(struct sctp_association * asoc,__u32 pmtu)1414 void sctp_assoc_set_pmtu(struct sctp_association *asoc, __u32 pmtu)
1415 {
1416 if (asoc->pathmtu != pmtu) {
1417 asoc->pathmtu = pmtu;
1418 sctp_assoc_update_frag_point(asoc);
1419 }
1420
1421 pr_debug("%s: asoc:%p, pmtu:%d, frag_point:%d\n", __func__, asoc,
1422 asoc->pathmtu, asoc->frag_point);
1423 }
1424
1425 /* Update the association's pmtu and frag_point by going through all the
1426 * transports. This routine is called when a transport's PMTU has changed.
1427 */
sctp_assoc_sync_pmtu(struct sctp_association * asoc)1428 void sctp_assoc_sync_pmtu(struct sctp_association *asoc)
1429 {
1430 struct sctp_transport *t;
1431 __u32 pmtu = 0;
1432
1433 if (!asoc)
1434 return;
1435
1436 /* Get the lowest pmtu of all the transports. */
1437 list_for_each_entry(t, &asoc->peer.transport_addr_list, transports) {
1438 if (t->pmtu_pending && t->dst) {
1439 sctp_transport_update_pmtu(t,
1440 atomic_read(&t->mtu_info));
1441 t->pmtu_pending = 0;
1442 }
1443 if (!pmtu || (t->pathmtu < pmtu))
1444 pmtu = t->pathmtu;
1445 }
1446
1447 sctp_assoc_set_pmtu(asoc, pmtu);
1448 }
1449
1450 /* Should we send a SACK to update our peer? */
sctp_peer_needs_update(struct sctp_association * asoc)1451 static inline bool sctp_peer_needs_update(struct sctp_association *asoc)
1452 {
1453 struct net *net = asoc->base.net;
1454
1455 switch (asoc->state) {
1456 case SCTP_STATE_ESTABLISHED:
1457 case SCTP_STATE_SHUTDOWN_PENDING:
1458 case SCTP_STATE_SHUTDOWN_RECEIVED:
1459 case SCTP_STATE_SHUTDOWN_SENT:
1460 if ((asoc->rwnd > asoc->a_rwnd) &&
1461 ((asoc->rwnd - asoc->a_rwnd) >= max_t(__u32,
1462 (asoc->base.sk->sk_rcvbuf >> net->sctp.rwnd_upd_shift),
1463 asoc->pathmtu)))
1464 return true;
1465 break;
1466 default:
1467 break;
1468 }
1469 return false;
1470 }
1471
1472 /* Increase asoc's rwnd by len and send any window update SACK if needed. */
sctp_assoc_rwnd_increase(struct sctp_association * asoc,unsigned int len)1473 void sctp_assoc_rwnd_increase(struct sctp_association *asoc, unsigned int len)
1474 {
1475 struct sctp_chunk *sack;
1476 struct timer_list *timer;
1477
1478 if (asoc->rwnd_over) {
1479 if (asoc->rwnd_over >= len) {
1480 asoc->rwnd_over -= len;
1481 } else {
1482 asoc->rwnd += (len - asoc->rwnd_over);
1483 asoc->rwnd_over = 0;
1484 }
1485 } else {
1486 asoc->rwnd += len;
1487 }
1488
1489 /* If we had window pressure, start recovering it
1490 * once our rwnd had reached the accumulated pressure
1491 * threshold. The idea is to recover slowly, but up
1492 * to the initial advertised window.
1493 */
1494 if (asoc->rwnd_press) {
1495 int change = min(asoc->pathmtu, asoc->rwnd_press);
1496 asoc->rwnd += change;
1497 asoc->rwnd_press -= change;
1498 }
1499
1500 pr_debug("%s: asoc:%p rwnd increased by %d to (%u, %u) - %u\n",
1501 __func__, asoc, len, asoc->rwnd, asoc->rwnd_over,
1502 asoc->a_rwnd);
1503
1504 /* Send a window update SACK if the rwnd has increased by at least the
1505 * minimum of the association's PMTU and half of the receive buffer.
1506 * The algorithm used is similar to the one described in
1507 * Section 4.2.3.3 of RFC 1122.
1508 */
1509 if (sctp_peer_needs_update(asoc)) {
1510 asoc->a_rwnd = asoc->rwnd;
1511
1512 pr_debug("%s: sending window update SACK- asoc:%p rwnd:%u "
1513 "a_rwnd:%u\n", __func__, asoc, asoc->rwnd,
1514 asoc->a_rwnd);
1515
1516 sack = sctp_make_sack(asoc);
1517 if (!sack)
1518 return;
1519
1520 asoc->peer.sack_needed = 0;
1521
1522 sctp_outq_tail(&asoc->outqueue, sack, GFP_ATOMIC);
1523
1524 /* Stop the SACK timer. */
1525 timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK];
1526 if (del_timer(timer))
1527 sctp_association_put(asoc);
1528 }
1529 }
1530
1531 /* Decrease asoc's rwnd by len. */
sctp_assoc_rwnd_decrease(struct sctp_association * asoc,unsigned int len)1532 void sctp_assoc_rwnd_decrease(struct sctp_association *asoc, unsigned int len)
1533 {
1534 int rx_count;
1535 int over = 0;
1536
1537 if (unlikely(!asoc->rwnd || asoc->rwnd_over))
1538 pr_debug("%s: association:%p has asoc->rwnd:%u, "
1539 "asoc->rwnd_over:%u!\n", __func__, asoc,
1540 asoc->rwnd, asoc->rwnd_over);
1541
1542 if (asoc->ep->rcvbuf_policy)
1543 rx_count = atomic_read(&asoc->rmem_alloc);
1544 else
1545 rx_count = atomic_read(&asoc->base.sk->sk_rmem_alloc);
1546
1547 /* If we've reached or overflowed our receive buffer, announce
1548 * a 0 rwnd if rwnd would still be positive. Store the
1549 * potential pressure overflow so that the window can be restored
1550 * back to original value.
1551 */
1552 if (rx_count >= asoc->base.sk->sk_rcvbuf)
1553 over = 1;
1554
1555 if (asoc->rwnd >= len) {
1556 asoc->rwnd -= len;
1557 if (over) {
1558 asoc->rwnd_press += asoc->rwnd;
1559 asoc->rwnd = 0;
1560 }
1561 } else {
1562 asoc->rwnd_over += len - asoc->rwnd;
1563 asoc->rwnd = 0;
1564 }
1565
1566 pr_debug("%s: asoc:%p rwnd decreased by %d to (%u, %u, %u)\n",
1567 __func__, asoc, len, asoc->rwnd, asoc->rwnd_over,
1568 asoc->rwnd_press);
1569 }
1570
1571 /* Build the bind address list for the association based on info from the
1572 * local endpoint and the remote peer.
1573 */
sctp_assoc_set_bind_addr_from_ep(struct sctp_association * asoc,enum sctp_scope scope,gfp_t gfp)1574 int sctp_assoc_set_bind_addr_from_ep(struct sctp_association *asoc,
1575 enum sctp_scope scope, gfp_t gfp)
1576 {
1577 struct sock *sk = asoc->base.sk;
1578 int flags;
1579
1580 /* Use scoping rules to determine the subset of addresses from
1581 * the endpoint.
1582 */
1583 flags = (PF_INET6 == sk->sk_family) ? SCTP_ADDR6_ALLOWED : 0;
1584 if (!inet_v6_ipv6only(sk))
1585 flags |= SCTP_ADDR4_ALLOWED;
1586 if (asoc->peer.ipv4_address)
1587 flags |= SCTP_ADDR4_PEERSUPP;
1588 if (asoc->peer.ipv6_address)
1589 flags |= SCTP_ADDR6_PEERSUPP;
1590
1591 return sctp_bind_addr_copy(asoc->base.net,
1592 &asoc->base.bind_addr,
1593 &asoc->ep->base.bind_addr,
1594 scope, gfp, flags);
1595 }
1596
1597 /* Build the association's bind address list from the cookie. */
sctp_assoc_set_bind_addr_from_cookie(struct sctp_association * asoc,struct sctp_cookie * cookie,gfp_t gfp)1598 int sctp_assoc_set_bind_addr_from_cookie(struct sctp_association *asoc,
1599 struct sctp_cookie *cookie,
1600 gfp_t gfp)
1601 {
1602 int var_size2 = ntohs(cookie->peer_init->chunk_hdr.length);
1603 int var_size3 = cookie->raw_addr_list_len;
1604 __u8 *raw = (__u8 *)cookie->peer_init + var_size2;
1605
1606 return sctp_raw_to_bind_addrs(&asoc->base.bind_addr, raw, var_size3,
1607 asoc->ep->base.bind_addr.port, gfp);
1608 }
1609
1610 /* Lookup laddr in the bind address list of an association. */
sctp_assoc_lookup_laddr(struct sctp_association * asoc,const union sctp_addr * laddr)1611 int sctp_assoc_lookup_laddr(struct sctp_association *asoc,
1612 const union sctp_addr *laddr)
1613 {
1614 int found = 0;
1615
1616 if ((asoc->base.bind_addr.port == ntohs(laddr->v4.sin_port)) &&
1617 sctp_bind_addr_match(&asoc->base.bind_addr, laddr,
1618 sctp_sk(asoc->base.sk)))
1619 found = 1;
1620
1621 return found;
1622 }
1623
1624 /* Set an association id for a given association */
sctp_assoc_set_id(struct sctp_association * asoc,gfp_t gfp)1625 int sctp_assoc_set_id(struct sctp_association *asoc, gfp_t gfp)
1626 {
1627 bool preload = gfpflags_allow_blocking(gfp);
1628 int ret;
1629
1630 /* If the id is already assigned, keep it. */
1631 if (asoc->assoc_id)
1632 return 0;
1633
1634 if (preload)
1635 idr_preload(gfp);
1636 spin_lock_bh(&sctp_assocs_id_lock);
1637 /* 0, 1, 2 are used as SCTP_FUTURE_ASSOC, SCTP_CURRENT_ASSOC and
1638 * SCTP_ALL_ASSOC, so an available id must be > SCTP_ALL_ASSOC.
1639 */
1640 ret = idr_alloc_cyclic(&sctp_assocs_id, asoc, SCTP_ALL_ASSOC + 1, 0,
1641 GFP_NOWAIT);
1642 spin_unlock_bh(&sctp_assocs_id_lock);
1643 if (preload)
1644 idr_preload_end();
1645 if (ret < 0)
1646 return ret;
1647
1648 asoc->assoc_id = (sctp_assoc_t)ret;
1649 return 0;
1650 }
1651
1652 /* Free the ASCONF queue */
sctp_assoc_free_asconf_queue(struct sctp_association * asoc)1653 static void sctp_assoc_free_asconf_queue(struct sctp_association *asoc)
1654 {
1655 struct sctp_chunk *asconf;
1656 struct sctp_chunk *tmp;
1657
1658 list_for_each_entry_safe(asconf, tmp, &asoc->addip_chunk_list, list) {
1659 list_del_init(&asconf->list);
1660 sctp_chunk_free(asconf);
1661 }
1662 }
1663
1664 /* Free asconf_ack cache */
sctp_assoc_free_asconf_acks(struct sctp_association * asoc)1665 static void sctp_assoc_free_asconf_acks(struct sctp_association *asoc)
1666 {
1667 struct sctp_chunk *ack;
1668 struct sctp_chunk *tmp;
1669
1670 list_for_each_entry_safe(ack, tmp, &asoc->asconf_ack_list,
1671 transmitted_list) {
1672 list_del_init(&ack->transmitted_list);
1673 sctp_chunk_free(ack);
1674 }
1675 }
1676
1677 /* Clean up the ASCONF_ACK queue */
sctp_assoc_clean_asconf_ack_cache(const struct sctp_association * asoc)1678 void sctp_assoc_clean_asconf_ack_cache(const struct sctp_association *asoc)
1679 {
1680 struct sctp_chunk *ack;
1681 struct sctp_chunk *tmp;
1682
1683 /* We can remove all the entries from the queue up to
1684 * the "Peer-Sequence-Number".
1685 */
1686 list_for_each_entry_safe(ack, tmp, &asoc->asconf_ack_list,
1687 transmitted_list) {
1688 if (ack->subh.addip_hdr->serial ==
1689 htonl(asoc->peer.addip_serial))
1690 break;
1691
1692 list_del_init(&ack->transmitted_list);
1693 sctp_chunk_free(ack);
1694 }
1695 }
1696
1697 /* Find the ASCONF_ACK whose serial number matches ASCONF */
sctp_assoc_lookup_asconf_ack(const struct sctp_association * asoc,__be32 serial)1698 struct sctp_chunk *sctp_assoc_lookup_asconf_ack(
1699 const struct sctp_association *asoc,
1700 __be32 serial)
1701 {
1702 struct sctp_chunk *ack;
1703
1704 /* Walk through the list of cached ASCONF-ACKs and find the
1705 * ack chunk whose serial number matches that of the request.
1706 */
1707 list_for_each_entry(ack, &asoc->asconf_ack_list, transmitted_list) {
1708 if (sctp_chunk_pending(ack))
1709 continue;
1710 if (ack->subh.addip_hdr->serial == serial) {
1711 sctp_chunk_hold(ack);
1712 return ack;
1713 }
1714 }
1715
1716 return NULL;
1717 }
1718
sctp_asconf_queue_teardown(struct sctp_association * asoc)1719 void sctp_asconf_queue_teardown(struct sctp_association *asoc)
1720 {
1721 /* Free any cached ASCONF_ACK chunk. */
1722 sctp_assoc_free_asconf_acks(asoc);
1723
1724 /* Free the ASCONF queue. */
1725 sctp_assoc_free_asconf_queue(asoc);
1726
1727 /* Free any cached ASCONF chunk. */
1728 if (asoc->addip_last_asconf)
1729 sctp_chunk_free(asoc->addip_last_asconf);
1730 }
1731