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