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(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(ep: asoc->ep);
70	sock_hold(sk: 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(r: &asoc->base.refcnt, n: 1);
77
78	/* Initialize the bind addr area. */
79	sctp_bind_addr_init(&asoc->base.bind_addr, port: ep->base.bind_addr.port);
80
81	asoc->state = SCTP_STATE_CLOSED;
82	asoc->cookie_life = ms_to_ktime(ms: 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(m: sp->rtoinfo.srto_initial);
94	asoc->rto_max = msecs_to_jiffies(m: sp->rtoinfo.srto_max);
95	asoc->rto_min = msecs_to_jiffies(m: 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(m: sp->hbinterval);
101	asoc->probe_interval = msecs_to_jiffies(m: 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(m: 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(m: 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(v: &asoc->rmem_alloc, i: 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(list: &asoc->addip_chunk_list);
203	INIT_LIST_HEAD(list: &asoc->asconf_ack_list);
204
205	/* Make an empty list of remote transport addresses. */
206	INIT_LIST_HEAD(list: &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(ulpq: &asoc->ulpq, asoc);
230
231	if (sctp_stream_init(stream: &asoc->stream, outcnt: asoc->c.sinit_num_ostreams, incnt: 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(list: &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(list: &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(buf: p+1, SCTP_AUTH_RANDOM_LENGTH);
274
275	return asoc;
276
277	stream_free:
278	sctp_stream_free(stream: &asoc->stream);
279	sock_put(sk: 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(size: sizeof(*asoc), flags: 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(objp: 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(head: &asoc->asocs)) {
324	list_del(entry: &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(map: &asoc->peer.tsn_map);
348
349	/* Free stream information. */
350	sctp_stream_free(stream: &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(timer: &asoc->timers[i]))
365	sctp_association_put(asoc);
366	}
367
368	/* Free peer's cached cookie. */
369	kfree(objp: asoc->peer.cookie);
370	kfree(objp: asoc->peer.peer_random);
371	kfree(objp: asoc->peer.peer_chunks);
372	kfree(objp: 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(entry: pos);
378	sctp_unhash_transport(t: 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(objp: asoc->asconf_addr_del_pending);
388
389	/* AUTH - Free the endpoint shared keys */
390	sctp_auth_destroy_keys(keys: &asoc->endpoint_shared_keys);
391
392	/* AUTH - Free the association shared key */
393	sctp_auth_key_put(key: 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(sk: asoc->base.sk);
408
409	if (asoc->assoc_id != 0) {
410	spin_lock_bh(lock: &sctp_assocs_id_lock);
411	idr_remove(&sctp_assocs_id, id: asoc->assoc_id);
412	spin_unlock_bh(lock: &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	state: SCTP_ADDR_MADE_PRIM, error: 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(entry: &peer->transports);
499	/* Remove this peer from the transport hashtable */
500	sctp_unhash_transport(t: 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(head: &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(list: &peer->transmitted,
559	head: &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(timer: &active->T3_rtx_timer))
566	if (!mod_timer(timer: &active->T3_rtx_timer,
567	expires: 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(transport: peer, state: SCTP_ADDR_REMOVED, error: 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(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, pmtu: 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, sport: asoc->base.bind_addr.port,
679	dport: 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, trans: 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(t: peer)) {
712	sctp_transport_free(peer);
713	return NULL;
714	}
715
716	sctp_transport_pl_reset(t: peer);
717
718	/* Attach the remote transport to our asoc. */
719	list_add_tail_rcu(new: &peer->transports, head: &asoc->peer.transport_addr_list);
720	asoc->peer.transport_count++;
721
722	sctp_ulpevent_notify_peer_addr_change(transport: peer, state: SCTP_ADDR_ADDED, error: 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, transport: 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(ss1: addr, ss2: &transport->ipaddr)) {
749	/* Do book keeping for removing the peer and free it. */
750	sctp_assoc_rm_peer(asoc, peer: 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(ss1: address, ss2: &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, peer: 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(t: 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(t: transport);
827	spc_state = SCTP_ADDR_UNREACHABLE;
828	} else {
829	sctp_transport_dst_release(t: 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	state: 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(r: &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(r: &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, lowest_tsn: 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(arg: 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(skb: 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(chunk: 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, event_type: SCTP_EVENT_T_CHUNK, subtype,
1052	state, ep, asoc, event_arg: 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(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(entry: &assoc->asocs);
1080
1081	/* Decrement the backlog value for a TCP-style socket. */
1082	if (sctp_style(oldsk, TCP))
1083	sk_acceptq_removed(sk: oldsk);
1084
1085	/* Release references to the old endpoint and the sock. */
1086	sctp_endpoint_put(assoc->ep);
1087	sock_put(sk: assoc->base.sk);
1088
1089	/* Get a reference to the new endpoint. */
1090	assoc->ep = newsp->ep;
1091	sctp_endpoint_hold(ep: assoc->ep);
1092
1093	/* Get a reference to the new sock. */
1094	assoc->base.sk = newsk;
1095	sock_hold(sk: 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	initial_tsn: 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(asoc: new, address: &trans->ipaddr)) {
1123	sctp_assoc_rm_peer(asoc, peer: trans);
1124	continue;
1125	}
1126
1127	if (asoc->state >= SCTP_STATE_ESTABLISHED)
1128	sctp_transport_reset(t: 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(stream: &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(ulpq: &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, addr: &trans->ipaddr,
1163	GFP_ATOMIC, peer_state: 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(stream: &asoc->stream, new: &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(objp: asoc->peer.peer_random);
1181	asoc->peer.peer_random = new->peer.peer_random;
1182	new->peer.peer_random = NULL;
1183
1184	kfree(objp: asoc->peer.peer_chunks);
1185	asoc->peer.peer_chunks = new->peer.peer_chunks;
1186	new->peer.peer_chunks = NULL;
1187
1188	kfree(objp: 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(cmp1: trans2->last_time_heard,
1244	cmp2: 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(trans: curr);
1260	score_best = sctp_trans_score(trans: 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(trans1: best, trans2: 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(curr: trans, best: 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(curr: trans, best: trans_pf);
1329	continue;
1330	}
1331	/* For active transports, pick the most recent ones. */
1332	if (trans_pri == NULL ||
1333	ktime_after(cmp1: trans->last_time_heard,
1334	cmp2: trans_pri->last_time_heard)) {
1335	trans_sec = trans_pri;
1336	trans_pri = trans;
1337	} else if (trans_sec == NULL ||
1338	ktime_after(cmp1: trans->last_time_heard,
1339	cmp2: 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(curr: asoc->peer.active_path, best: 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(sp: sctp_sk(sk: asoc->base.sk), mtu: asoc->pathmtu,
1400	extra: sctp_datachk_len(stream: &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	pmtu: atomic_read(v: &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, chunk: 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(v: &asoc->rmem_alloc);
1541	else
1542	rx_count = atomic_read(v: &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(net: asoc->base.net,
1589	dest: &asoc->base.bind_addr,
1590	src: &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(bp: &asoc->base.bind_addr, raw, len: var_size3,
1605	port: 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(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_flags: 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_mask: gfp);
1634	spin_lock_bh(lock: &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, ptr: asoc, SCTP_ALL_ASSOC + 1, end: 0,
1639	GFP_NOWAIT);
1640	spin_unlock_bh(lock: &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(entry: &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(entry: &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(entry: &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(chunk: 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