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TOMOYO Linux Cross Reference
Linux/net/sctp/associola.c

Version: ~ [ linux-5.3-rc5 ] ~ [ linux-5.2.9 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.67 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.139 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.189 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.189 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.72 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
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  1 /* SCTP kernel implementation
  2  * (C) Copyright IBM Corp. 2001, 2004
  3  * Copyright (c) 1999-2000 Cisco, Inc.
  4  * Copyright (c) 1999-2001 Motorola, Inc.
  5  * Copyright (c) 2001 Intel Corp.
  6  * Copyright (c) 2001 La Monte H.P. Yarroll
  7  *
  8  * This file is part of the SCTP kernel implementation
  9  *
 10  * This module provides the abstraction for an SCTP association.
 11  *
 12  * This SCTP implementation is free software;
 13  * you can redistribute it and/or modify it under the terms of
 14  * the GNU General Public License as published by
 15  * the Free Software Foundation; either version 2, or (at your option)
 16  * any later version.
 17  *
 18  * This SCTP implementation is distributed in the hope that it
 19  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
 20  *                 ************************
 21  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 22  * See the GNU General Public License for more details.
 23  *
 24  * You should have received a copy of the GNU General Public License
 25  * along with GNU CC; see the file COPYING.  If not, see
 26  * <http://www.gnu.org/licenses/>.
 27  *
 28  * Please send any bug reports or fixes you make to the
 29  * email address(es):
 30  *    lksctp developers <linux-sctp@vger.kernel.org>
 31  *
 32  * Written or modified by:
 33  *    La Monte H.P. Yarroll <piggy@acm.org>
 34  *    Karl Knutson          <karl@athena.chicago.il.us>
 35  *    Jon Grimm             <jgrimm@us.ibm.com>
 36  *    Xingang Guo           <xingang.guo@intel.com>
 37  *    Hui Huang             <hui.huang@nokia.com>
 38  *    Sridhar Samudrala     <sri@us.ibm.com>
 39  *    Daisy Chang           <daisyc@us.ibm.com>
 40  *    Ryan Layer            <rmlayer@us.ibm.com>
 41  *    Kevin Gao             <kevin.gao@intel.com>
 42  */
 43 
 44 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 45 
 46 #include <linux/types.h>
 47 #include <linux/fcntl.h>
 48 #include <linux/poll.h>
 49 #include <linux/init.h>
 50 
 51 #include <linux/slab.h>
 52 #include <linux/in.h>
 53 #include <net/ipv6.h>
 54 #include <net/sctp/sctp.h>
 55 #include <net/sctp/sm.h>
 56 
 57 /* Forward declarations for internal functions. */
 58 static void sctp_select_active_and_retran_path(struct sctp_association *asoc);
 59 static void sctp_assoc_bh_rcv(struct work_struct *work);
 60 static void sctp_assoc_free_asconf_acks(struct sctp_association *asoc);
 61 static void sctp_assoc_free_asconf_queue(struct sctp_association *asoc);
 62 
 63 /* 1st Level Abstractions. */
 64 
 65 /* Initialize a new association from provided memory. */
 66 static struct sctp_association *sctp_association_init(struct sctp_association *asoc,
 67                                           const struct sctp_endpoint *ep,
 68                                           const struct sock *sk,
 69                                           sctp_scope_t scope,
 70                                           gfp_t gfp)
 71 {
 72         struct net *net = sock_net(sk);
 73         struct sctp_sock *sp;
 74         int i;
 75         sctp_paramhdr_t *p;
 76         int err;
 77 
 78         /* Retrieve the SCTP per socket area.  */
 79         sp = sctp_sk((struct sock *)sk);
 80 
 81         /* Discarding const is appropriate here.  */
 82         asoc->ep = (struct sctp_endpoint *)ep;
 83         asoc->base.sk = (struct sock *)sk;
 84 
 85         sctp_endpoint_hold(asoc->ep);
 86         sock_hold(asoc->base.sk);
 87 
 88         /* Initialize the common base substructure.  */
 89         asoc->base.type = SCTP_EP_TYPE_ASSOCIATION;
 90 
 91         /* Initialize the object handling fields.  */
 92         atomic_set(&asoc->base.refcnt, 1);
 93 
 94         /* Initialize the bind addr area.  */
 95         sctp_bind_addr_init(&asoc->base.bind_addr, ep->base.bind_addr.port);
 96 
 97         asoc->state = SCTP_STATE_CLOSED;
 98         asoc->cookie_life = ms_to_ktime(sp->assocparams.sasoc_cookie_life);
 99         asoc->user_frag = sp->user_frag;
100 
101         /* Set the association max_retrans and RTO values from the
102          * socket values.
103          */
104         asoc->max_retrans = sp->assocparams.sasoc_asocmaxrxt;
105         asoc->pf_retrans  = net->sctp.pf_retrans;
106 
107         asoc->rto_initial = msecs_to_jiffies(sp->rtoinfo.srto_initial);
108         asoc->rto_max = msecs_to_jiffies(sp->rtoinfo.srto_max);
109         asoc->rto_min = msecs_to_jiffies(sp->rtoinfo.srto_min);
110 
111         /* Initialize the association's heartbeat interval based on the
112          * sock configured value.
113          */
114         asoc->hbinterval = msecs_to_jiffies(sp->hbinterval);
115 
116         /* Initialize path max retrans value. */
117         asoc->pathmaxrxt = sp->pathmaxrxt;
118 
119         /* Initialize default path MTU. */
120         asoc->pathmtu = sp->pathmtu;
121 
122         /* Set association default SACK delay */
123         asoc->sackdelay = msecs_to_jiffies(sp->sackdelay);
124         asoc->sackfreq = sp->sackfreq;
125 
126         /* Set the association default flags controlling
127          * Heartbeat, SACK delay, and Path MTU Discovery.
128          */
129         asoc->param_flags = sp->param_flags;
130 
131         /* Initialize the maximum number of new data packets that can be sent
132          * in a burst.
133          */
134         asoc->max_burst = sp->max_burst;
135 
136         /* initialize association timers */
137         asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_COOKIE] = asoc->rto_initial;
138         asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_INIT] = asoc->rto_initial;
139         asoc->timeouts[SCTP_EVENT_TIMEOUT_T2_SHUTDOWN] = asoc->rto_initial;
140 
141         /* sctpimpguide Section 2.12.2
142          * If the 'T5-shutdown-guard' timer is used, it SHOULD be set to the
143          * recommended value of 5 times 'RTO.Max'.
144          */
145         asoc->timeouts[SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]
146                 = 5 * asoc->rto_max;
147 
148         asoc->timeouts[SCTP_EVENT_TIMEOUT_SACK] = asoc->sackdelay;
149         asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE] = sp->autoclose * HZ;
150 
151         /* Initializes the timers */
152         for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i)
153                 setup_timer(&asoc->timers[i], sctp_timer_events[i],
154                                 (unsigned long)asoc);
155 
156         /* Pull default initialization values from the sock options.
157          * Note: This assumes that the values have already been
158          * validated in the sock.
159          */
160         asoc->c.sinit_max_instreams = sp->initmsg.sinit_max_instreams;
161         asoc->c.sinit_num_ostreams  = sp->initmsg.sinit_num_ostreams;
162         asoc->max_init_attempts = sp->initmsg.sinit_max_attempts;
163 
164         asoc->max_init_timeo =
165                  msecs_to_jiffies(sp->initmsg.sinit_max_init_timeo);
166 
167         /* Set the local window size for receive.
168          * This is also the rcvbuf space per association.
169          * RFC 6 - A SCTP receiver MUST be able to receive a minimum of
170          * 1500 bytes in one SCTP packet.
171          */
172         if ((sk->sk_rcvbuf/2) < SCTP_DEFAULT_MINWINDOW)
173                 asoc->rwnd = SCTP_DEFAULT_MINWINDOW;
174         else
175                 asoc->rwnd = sk->sk_rcvbuf/2;
176 
177         asoc->a_rwnd = asoc->rwnd;
178 
179         /* Use my own max window until I learn something better.  */
180         asoc->peer.rwnd = SCTP_DEFAULT_MAXWINDOW;
181 
182         /* Initialize the receive memory counter */
183         atomic_set(&asoc->rmem_alloc, 0);
184 
185         init_waitqueue_head(&asoc->wait);
186 
187         asoc->c.my_vtag = sctp_generate_tag(ep);
188         asoc->c.my_port = ep->base.bind_addr.port;
189 
190         asoc->c.initial_tsn = sctp_generate_tsn(ep);
191 
192         asoc->next_tsn = asoc->c.initial_tsn;
193 
194         asoc->ctsn_ack_point = asoc->next_tsn - 1;
195         asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
196         asoc->highest_sacked = asoc->ctsn_ack_point;
197         asoc->last_cwr_tsn = asoc->ctsn_ack_point;
198 
199         /* ADDIP Section 4.1 Asconf Chunk Procedures
200          *
201          * When an endpoint has an ASCONF signaled change to be sent to the
202          * remote endpoint it should do the following:
203          * ...
204          * A2) a serial number should be assigned to the chunk. The serial
205          * number SHOULD be a monotonically increasing number. The serial
206          * numbers SHOULD be initialized at the start of the
207          * association to the same value as the initial TSN.
208          */
209         asoc->addip_serial = asoc->c.initial_tsn;
210 
211         INIT_LIST_HEAD(&asoc->addip_chunk_list);
212         INIT_LIST_HEAD(&asoc->asconf_ack_list);
213 
214         /* Make an empty list of remote transport addresses.  */
215         INIT_LIST_HEAD(&asoc->peer.transport_addr_list);
216 
217         /* RFC 2960 5.1 Normal Establishment of an Association
218          *
219          * After the reception of the first data chunk in an
220          * association the endpoint must immediately respond with a
221          * sack to acknowledge the data chunk.  Subsequent
222          * acknowledgements should be done as described in Section
223          * 6.2.
224          *
225          * [We implement this by telling a new association that it
226          * already received one packet.]
227          */
228         asoc->peer.sack_needed = 1;
229         asoc->peer.sack_generation = 1;
230 
231         /* Assume that the peer will tell us if he recognizes ASCONF
232          * as part of INIT exchange.
233          * The sctp_addip_noauth option is there for backward compatibility
234          * and will revert old behavior.
235          */
236         if (net->sctp.addip_noauth)
237                 asoc->peer.asconf_capable = 1;
238 
239         /* Create an input queue.  */
240         sctp_inq_init(&asoc->base.inqueue);
241         sctp_inq_set_th_handler(&asoc->base.inqueue, sctp_assoc_bh_rcv);
242 
243         /* Create an output queue.  */
244         sctp_outq_init(asoc, &asoc->outqueue);
245 
246         if (!sctp_ulpq_init(&asoc->ulpq, asoc))
247                 goto fail_init;
248 
249         /* Assume that peer would support both address types unless we are
250          * told otherwise.
251          */
252         asoc->peer.ipv4_address = 1;
253         if (asoc->base.sk->sk_family == PF_INET6)
254                 asoc->peer.ipv6_address = 1;
255         INIT_LIST_HEAD(&asoc->asocs);
256 
257         asoc->default_stream = sp->default_stream;
258         asoc->default_ppid = sp->default_ppid;
259         asoc->default_flags = sp->default_flags;
260         asoc->default_context = sp->default_context;
261         asoc->default_timetolive = sp->default_timetolive;
262         asoc->default_rcv_context = sp->default_rcv_context;
263 
264         /* AUTH related initializations */
265         INIT_LIST_HEAD(&asoc->endpoint_shared_keys);
266         err = sctp_auth_asoc_copy_shkeys(ep, asoc, gfp);
267         if (err)
268                 goto fail_init;
269 
270         asoc->active_key_id = ep->active_key_id;
271 
272         /* Save the hmacs and chunks list into this association */
273         if (ep->auth_hmacs_list)
274                 memcpy(asoc->c.auth_hmacs, ep->auth_hmacs_list,
275                         ntohs(ep->auth_hmacs_list->param_hdr.length));
276         if (ep->auth_chunk_list)
277                 memcpy(asoc->c.auth_chunks, ep->auth_chunk_list,
278                         ntohs(ep->auth_chunk_list->param_hdr.length));
279 
280         /* Get the AUTH random number for this association */
281         p = (sctp_paramhdr_t *)asoc->c.auth_random;
282         p->type = SCTP_PARAM_RANDOM;
283         p->length = htons(sizeof(sctp_paramhdr_t) + SCTP_AUTH_RANDOM_LENGTH);
284         get_random_bytes(p+1, SCTP_AUTH_RANDOM_LENGTH);
285 
286         return asoc;
287 
288 fail_init:
289         sock_put(asoc->base.sk);
290         sctp_endpoint_put(asoc->ep);
291         return NULL;
292 }
293 
294 /* Allocate and initialize a new association */
295 struct sctp_association *sctp_association_new(const struct sctp_endpoint *ep,
296                                          const struct sock *sk,
297                                          sctp_scope_t scope,
298                                          gfp_t gfp)
299 {
300         struct sctp_association *asoc;
301 
302         asoc = kzalloc(sizeof(*asoc), gfp);
303         if (!asoc)
304                 goto fail;
305 
306         if (!sctp_association_init(asoc, ep, sk, scope, gfp))
307                 goto fail_init;
308 
309         SCTP_DBG_OBJCNT_INC(assoc);
310 
311         pr_debug("Created asoc %p\n", asoc);
312 
313         return asoc;
314 
315 fail_init:
316         kfree(asoc);
317 fail:
318         return NULL;
319 }
320 
321 /* Free this association if possible.  There may still be users, so
322  * the actual deallocation may be delayed.
323  */
324 void sctp_association_free(struct sctp_association *asoc)
325 {
326         struct sock *sk = asoc->base.sk;
327         struct sctp_transport *transport;
328         struct list_head *pos, *temp;
329         int i;
330 
331         /* Only real associations count against the endpoint, so
332          * don't bother for if this is a temporary association.
333          */
334         if (!list_empty(&asoc->asocs)) {
335                 list_del(&asoc->asocs);
336 
337                 /* Decrement the backlog value for a TCP-style listening
338                  * socket.
339                  */
340                 if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
341                         sk->sk_ack_backlog--;
342         }
343 
344         /* Mark as dead, so other users can know this structure is
345          * going away.
346          */
347         asoc->base.dead = true;
348 
349         /* Dispose of any data lying around in the outqueue. */
350         sctp_outq_free(&asoc->outqueue);
351 
352         /* Dispose of any pending messages for the upper layer. */
353         sctp_ulpq_free(&asoc->ulpq);
354 
355         /* Dispose of any pending chunks on the inqueue. */
356         sctp_inq_free(&asoc->base.inqueue);
357 
358         sctp_tsnmap_free(&asoc->peer.tsn_map);
359 
360         /* Free ssnmap storage. */
361         sctp_ssnmap_free(asoc->ssnmap);
362 
363         /* Clean up the bound address list. */
364         sctp_bind_addr_free(&asoc->base.bind_addr);
365 
366         /* Do we need to go through all of our timers and
367          * delete them?   To be safe we will try to delete all, but we
368          * should be able to go through and make a guess based
369          * on our state.
370          */
371         for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i) {
372                 if (del_timer(&asoc->timers[i]))
373                         sctp_association_put(asoc);
374         }
375 
376         /* Free peer's cached cookie. */
377         kfree(asoc->peer.cookie);
378         kfree(asoc->peer.peer_random);
379         kfree(asoc->peer.peer_chunks);
380         kfree(asoc->peer.peer_hmacs);
381 
382         /* Release the transport structures. */
383         list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
384                 transport = list_entry(pos, struct sctp_transport, transports);
385                 list_del_rcu(pos);
386                 sctp_transport_free(transport);
387         }
388 
389         asoc->peer.transport_count = 0;
390 
391         sctp_asconf_queue_teardown(asoc);
392 
393         /* Free pending address space being deleted */
394         kfree(asoc->asconf_addr_del_pending);
395 
396         /* AUTH - Free the endpoint shared keys */
397         sctp_auth_destroy_keys(&asoc->endpoint_shared_keys);
398 
399         /* AUTH - Free the association shared key */
400         sctp_auth_key_put(asoc->asoc_shared_key);
401 
402         sctp_association_put(asoc);
403 }
404 
405 /* Cleanup and free up an association. */
406 static void sctp_association_destroy(struct sctp_association *asoc)
407 {
408         if (unlikely(!asoc->base.dead)) {
409                 WARN(1, "Attempt to destroy undead association %p!\n", asoc);
410                 return;
411         }
412 
413         sctp_endpoint_put(asoc->ep);
414         sock_put(asoc->base.sk);
415 
416         if (asoc->assoc_id != 0) {
417                 spin_lock_bh(&sctp_assocs_id_lock);
418                 idr_remove(&sctp_assocs_id, asoc->assoc_id);
419                 spin_unlock_bh(&sctp_assocs_id_lock);
420         }
421 
422         WARN_ON(atomic_read(&asoc->rmem_alloc));
423 
424         kfree(asoc);
425         SCTP_DBG_OBJCNT_DEC(assoc);
426 }
427 
428 /* Change the primary destination address for the peer. */
429 void sctp_assoc_set_primary(struct sctp_association *asoc,
430                             struct sctp_transport *transport)
431 {
432         int changeover = 0;
433 
434         /* it's a changeover only if we already have a primary path
435          * that we are changing
436          */
437         if (asoc->peer.primary_path != NULL &&
438             asoc->peer.primary_path != transport)
439                 changeover = 1 ;
440 
441         asoc->peer.primary_path = transport;
442 
443         /* Set a default msg_name for events. */
444         memcpy(&asoc->peer.primary_addr, &transport->ipaddr,
445                sizeof(union sctp_addr));
446 
447         /* If the primary path is changing, assume that the
448          * user wants to use this new path.
449          */
450         if ((transport->state == SCTP_ACTIVE) ||
451             (transport->state == SCTP_UNKNOWN))
452                 asoc->peer.active_path = transport;
453 
454         /*
455          * SFR-CACC algorithm:
456          * Upon the receipt of a request to change the primary
457          * destination address, on the data structure for the new
458          * primary destination, the sender MUST do the following:
459          *
460          * 1) If CHANGEOVER_ACTIVE is set, then there was a switch
461          * to this destination address earlier. The sender MUST set
462          * CYCLING_CHANGEOVER to indicate that this switch is a
463          * double switch to the same destination address.
464          *
465          * Really, only bother is we have data queued or outstanding on
466          * the association.
467          */
468         if (!asoc->outqueue.outstanding_bytes && !asoc->outqueue.out_qlen)
469                 return;
470 
471         if (transport->cacc.changeover_active)
472                 transport->cacc.cycling_changeover = changeover;
473 
474         /* 2) The sender MUST set CHANGEOVER_ACTIVE to indicate that
475          * a changeover has occurred.
476          */
477         transport->cacc.changeover_active = changeover;
478 
479         /* 3) The sender MUST store the next TSN to be sent in
480          * next_tsn_at_change.
481          */
482         transport->cacc.next_tsn_at_change = asoc->next_tsn;
483 }
484 
485 /* Remove a transport from an association.  */
486 void sctp_assoc_rm_peer(struct sctp_association *asoc,
487                         struct sctp_transport *peer)
488 {
489         struct list_head        *pos;
490         struct sctp_transport   *transport;
491 
492         pr_debug("%s: association:%p addr:%pISpc\n",
493                  __func__, asoc, &peer->ipaddr.sa);
494 
495         /* If we are to remove the current retran_path, update it
496          * to the next peer before removing this peer from the list.
497          */
498         if (asoc->peer.retran_path == peer)
499                 sctp_assoc_update_retran_path(asoc);
500 
501         /* Remove this peer from the list. */
502         list_del_rcu(&peer->transports);
503 
504         /* Get the first transport of asoc. */
505         pos = asoc->peer.transport_addr_list.next;
506         transport = list_entry(pos, struct sctp_transport, transports);
507 
508         /* Update any entries that match the peer to be deleted. */
509         if (asoc->peer.primary_path == peer)
510                 sctp_assoc_set_primary(asoc, transport);
511         if (asoc->peer.active_path == peer)
512                 asoc->peer.active_path = transport;
513         if (asoc->peer.retran_path == peer)
514                 asoc->peer.retran_path = transport;
515         if (asoc->peer.last_data_from == peer)
516                 asoc->peer.last_data_from = transport;
517 
518         /* If we remove the transport an INIT was last sent to, set it to
519          * NULL. Combined with the update of the retran path above, this
520          * will cause the next INIT to be sent to the next available
521          * transport, maintaining the cycle.
522          */
523         if (asoc->init_last_sent_to == peer)
524                 asoc->init_last_sent_to = NULL;
525 
526         /* If we remove the transport an SHUTDOWN was last sent to, set it
527          * to NULL. Combined with the update of the retran path above, this
528          * will cause the next SHUTDOWN to be sent to the next available
529          * transport, maintaining the cycle.
530          */
531         if (asoc->shutdown_last_sent_to == peer)
532                 asoc->shutdown_last_sent_to = NULL;
533 
534         /* If we remove the transport an ASCONF was last sent to, set it to
535          * NULL.
536          */
537         if (asoc->addip_last_asconf &&
538             asoc->addip_last_asconf->transport == peer)
539                 asoc->addip_last_asconf->transport = NULL;
540 
541         /* If we have something on the transmitted list, we have to
542          * save it off.  The best place is the active path.
543          */
544         if (!list_empty(&peer->transmitted)) {
545                 struct sctp_transport *active = asoc->peer.active_path;
546                 struct sctp_chunk *ch;
547 
548                 /* Reset the transport of each chunk on this list */
549                 list_for_each_entry(ch, &peer->transmitted,
550                                         transmitted_list) {
551                         ch->transport = NULL;
552                         ch->rtt_in_progress = 0;
553                 }
554 
555                 list_splice_tail_init(&peer->transmitted,
556                                         &active->transmitted);
557 
558                 /* Start a T3 timer here in case it wasn't running so
559                  * that these migrated packets have a chance to get
560                  * retransmitted.
561                  */
562                 if (!timer_pending(&active->T3_rtx_timer))
563                         if (!mod_timer(&active->T3_rtx_timer,
564                                         jiffies + active->rto))
565                                 sctp_transport_hold(active);
566         }
567 
568         asoc->peer.transport_count--;
569 
570         sctp_transport_free(peer);
571 }
572 
573 /* Add a transport address to an association.  */
574 struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc,
575                                            const union sctp_addr *addr,
576                                            const gfp_t gfp,
577                                            const int peer_state)
578 {
579         struct net *net = sock_net(asoc->base.sk);
580         struct sctp_transport *peer;
581         struct sctp_sock *sp;
582         unsigned short port;
583 
584         sp = sctp_sk(asoc->base.sk);
585 
586         /* AF_INET and AF_INET6 share common port field. */
587         port = ntohs(addr->v4.sin_port);
588 
589         pr_debug("%s: association:%p addr:%pISpc state:%d\n", __func__,
590                  asoc, &addr->sa, peer_state);
591 
592         /* Set the port if it has not been set yet.  */
593         if (0 == asoc->peer.port)
594                 asoc->peer.port = port;
595 
596         /* Check to see if this is a duplicate. */
597         peer = sctp_assoc_lookup_paddr(asoc, addr);
598         if (peer) {
599                 /* An UNKNOWN state is only set on transports added by
600                  * user in sctp_connectx() call.  Such transports should be
601                  * considered CONFIRMED per RFC 4960, Section 5.4.
602                  */
603                 if (peer->state == SCTP_UNKNOWN) {
604                         peer->state = SCTP_ACTIVE;
605                 }
606                 return peer;
607         }
608 
609         peer = sctp_transport_new(net, addr, gfp);
610         if (!peer)
611                 return NULL;
612 
613         sctp_transport_set_owner(peer, asoc);
614 
615         /* Initialize the peer's heartbeat interval based on the
616          * association configured value.
617          */
618         peer->hbinterval = asoc->hbinterval;
619 
620         /* Set the path max_retrans.  */
621         peer->pathmaxrxt = asoc->pathmaxrxt;
622 
623         /* And the partial failure retrans threshold */
624         peer->pf_retrans = asoc->pf_retrans;
625 
626         /* Initialize the peer's SACK delay timeout based on the
627          * association configured value.
628          */
629         peer->sackdelay = asoc->sackdelay;
630         peer->sackfreq = asoc->sackfreq;
631 
632         /* Enable/disable heartbeat, SACK delay, and path MTU discovery
633          * based on association setting.
634          */
635         peer->param_flags = asoc->param_flags;
636 
637         sctp_transport_route(peer, NULL, sp);
638 
639         /* Initialize the pmtu of the transport. */
640         if (peer->param_flags & SPP_PMTUD_DISABLE) {
641                 if (asoc->pathmtu)
642                         peer->pathmtu = asoc->pathmtu;
643                 else
644                         peer->pathmtu = SCTP_DEFAULT_MAXSEGMENT;
645         }
646 
647         /* If this is the first transport addr on this association,
648          * initialize the association PMTU to the peer's PMTU.
649          * If not and the current association PMTU is higher than the new
650          * peer's PMTU, reset the association PMTU to the new peer's PMTU.
651          */
652         if (asoc->pathmtu)
653                 asoc->pathmtu = min_t(int, peer->pathmtu, asoc->pathmtu);
654         else
655                 asoc->pathmtu = peer->pathmtu;
656 
657         pr_debug("%s: association:%p PMTU set to %d\n", __func__, asoc,
658                  asoc->pathmtu);
659 
660         peer->pmtu_pending = 0;
661 
662         asoc->frag_point = sctp_frag_point(asoc, asoc->pathmtu);
663 
664         /* The asoc->peer.port might not be meaningful yet, but
665          * initialize the packet structure anyway.
666          */
667         sctp_packet_init(&peer->packet, peer, asoc->base.bind_addr.port,
668                          asoc->peer.port);
669 
670         /* 7.2.1 Slow-Start
671          *
672          * o The initial cwnd before DATA transmission or after a sufficiently
673          *   long idle period MUST be set to
674          *      min(4*MTU, max(2*MTU, 4380 bytes))
675          *
676          * o The initial value of ssthresh MAY be arbitrarily high
677          *   (for example, implementations MAY use the size of the
678          *   receiver advertised window).
679          */
680         peer->cwnd = min(4*asoc->pathmtu, max_t(__u32, 2*asoc->pathmtu, 4380));
681 
682         /* At this point, we may not have the receiver's advertised window,
683          * so initialize ssthresh to the default value and it will be set
684          * later when we process the INIT.
685          */
686         peer->ssthresh = SCTP_DEFAULT_MAXWINDOW;
687 
688         peer->partial_bytes_acked = 0;
689         peer->flight_size = 0;
690         peer->burst_limited = 0;
691 
692         /* Set the transport's RTO.initial value */
693         peer->rto = asoc->rto_initial;
694         sctp_max_rto(asoc, peer);
695 
696         /* Set the peer's active state. */
697         peer->state = peer_state;
698 
699         /* Attach the remote transport to our asoc.  */
700         list_add_tail_rcu(&peer->transports, &asoc->peer.transport_addr_list);
701         asoc->peer.transport_count++;
702 
703         /* If we do not yet have a primary path, set one.  */
704         if (!asoc->peer.primary_path) {
705                 sctp_assoc_set_primary(asoc, peer);
706                 asoc->peer.retran_path = peer;
707         }
708 
709         if (asoc->peer.active_path == asoc->peer.retran_path &&
710             peer->state != SCTP_UNCONFIRMED) {
711                 asoc->peer.retran_path = peer;
712         }
713 
714         return peer;
715 }
716 
717 /* Delete a transport address from an association.  */
718 void sctp_assoc_del_peer(struct sctp_association *asoc,
719                          const union sctp_addr *addr)
720 {
721         struct list_head        *pos;
722         struct list_head        *temp;
723         struct sctp_transport   *transport;
724 
725         list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
726                 transport = list_entry(pos, struct sctp_transport, transports);
727                 if (sctp_cmp_addr_exact(addr, &transport->ipaddr)) {
728                         /* Do book keeping for removing the peer and free it. */
729                         sctp_assoc_rm_peer(asoc, transport);
730                         break;
731                 }
732         }
733 }
734 
735 /* Lookup a transport by address. */
736 struct sctp_transport *sctp_assoc_lookup_paddr(
737                                         const struct sctp_association *asoc,
738                                         const union sctp_addr *address)
739 {
740         struct sctp_transport *t;
741 
742         /* Cycle through all transports searching for a peer address. */
743 
744         list_for_each_entry(t, &asoc->peer.transport_addr_list,
745                         transports) {
746                 if (sctp_cmp_addr_exact(address, &t->ipaddr))
747                         return t;
748         }
749 
750         return NULL;
751 }
752 
753 /* Remove all transports except a give one */
754 void sctp_assoc_del_nonprimary_peers(struct sctp_association *asoc,
755                                      struct sctp_transport *primary)
756 {
757         struct sctp_transport   *temp;
758         struct sctp_transport   *t;
759 
760         list_for_each_entry_safe(t, temp, &asoc->peer.transport_addr_list,
761                                  transports) {
762                 /* if the current transport is not the primary one, delete it */
763                 if (t != primary)
764                         sctp_assoc_rm_peer(asoc, t);
765         }
766 }
767 
768 /* Engage in transport control operations.
769  * Mark the transport up or down and send a notification to the user.
770  * Select and update the new active and retran paths.
771  */
772 void sctp_assoc_control_transport(struct sctp_association *asoc,
773                                   struct sctp_transport *transport,
774                                   sctp_transport_cmd_t command,
775                                   sctp_sn_error_t error)
776 {
777         struct sctp_ulpevent *event;
778         struct sockaddr_storage addr;
779         int spc_state = 0;
780         bool ulp_notify = true;
781 
782         /* Record the transition on the transport.  */
783         switch (command) {
784         case SCTP_TRANSPORT_UP:
785                 /* If we are moving from UNCONFIRMED state due
786                  * to heartbeat success, report the SCTP_ADDR_CONFIRMED
787                  * state to the user, otherwise report SCTP_ADDR_AVAILABLE.
788                  */
789                 if (SCTP_UNCONFIRMED == transport->state &&
790                     SCTP_HEARTBEAT_SUCCESS == error)
791                         spc_state = SCTP_ADDR_CONFIRMED;
792                 else
793                         spc_state = SCTP_ADDR_AVAILABLE;
794                 /* Don't inform ULP about transition from PF to
795                  * active state and set cwnd to 1 MTU, see SCTP
796                  * Quick failover draft section 5.1, point 5
797                  */
798                 if (transport->state == SCTP_PF) {
799                         ulp_notify = false;
800                         transport->cwnd = asoc->pathmtu;
801                 }
802                 transport->state = SCTP_ACTIVE;
803                 break;
804 
805         case SCTP_TRANSPORT_DOWN:
806                 /* If the transport was never confirmed, do not transition it
807                  * to inactive state.  Also, release the cached route since
808                  * there may be a better route next time.
809                  */
810                 if (transport->state != SCTP_UNCONFIRMED)
811                         transport->state = SCTP_INACTIVE;
812                 else {
813                         dst_release(transport->dst);
814                         transport->dst = NULL;
815                         ulp_notify = false;
816                 }
817 
818                 spc_state = SCTP_ADDR_UNREACHABLE;
819                 break;
820 
821         case SCTP_TRANSPORT_PF:
822                 transport->state = SCTP_PF;
823                 ulp_notify = false;
824                 break;
825 
826         default:
827                 return;
828         }
829 
830         /* Generate and send a SCTP_PEER_ADDR_CHANGE notification
831          * to the user.
832          */
833         if (ulp_notify) {
834                 memset(&addr, 0, sizeof(struct sockaddr_storage));
835                 memcpy(&addr, &transport->ipaddr,
836                        transport->af_specific->sockaddr_len);
837 
838                 event = sctp_ulpevent_make_peer_addr_change(asoc, &addr,
839                                         0, spc_state, error, GFP_ATOMIC);
840                 if (event)
841                         sctp_ulpq_tail_event(&asoc->ulpq, event);
842         }
843 
844         /* Select new active and retran paths. */
845         sctp_select_active_and_retran_path(asoc);
846 }
847 
848 /* Hold a reference to an association. */
849 void sctp_association_hold(struct sctp_association *asoc)
850 {
851         atomic_inc(&asoc->base.refcnt);
852 }
853 
854 /* Release a reference to an association and cleanup
855  * if there are no more references.
856  */
857 void sctp_association_put(struct sctp_association *asoc)
858 {
859         if (atomic_dec_and_test(&asoc->base.refcnt))
860                 sctp_association_destroy(asoc);
861 }
862 
863 /* Allocate the next TSN, Transmission Sequence Number, for the given
864  * association.
865  */
866 __u32 sctp_association_get_next_tsn(struct sctp_association *asoc)
867 {
868         /* From Section 1.6 Serial Number Arithmetic:
869          * Transmission Sequence Numbers wrap around when they reach
870          * 2**32 - 1.  That is, the next TSN a DATA chunk MUST use
871          * after transmitting TSN = 2*32 - 1 is TSN = 0.
872          */
873         __u32 retval = asoc->next_tsn;
874         asoc->next_tsn++;
875         asoc->unack_data++;
876 
877         return retval;
878 }
879 
880 /* Compare two addresses to see if they match.  Wildcard addresses
881  * only match themselves.
882  */
883 int sctp_cmp_addr_exact(const union sctp_addr *ss1,
884                         const union sctp_addr *ss2)
885 {
886         struct sctp_af *af;
887 
888         af = sctp_get_af_specific(ss1->sa.sa_family);
889         if (unlikely(!af))
890                 return 0;
891 
892         return af->cmp_addr(ss1, ss2);
893 }
894 
895 /* Return an ecne chunk to get prepended to a packet.
896  * Note:  We are sly and return a shared, prealloced chunk.  FIXME:
897  * No we don't, but we could/should.
898  */
899 struct sctp_chunk *sctp_get_ecne_prepend(struct sctp_association *asoc)
900 {
901         if (!asoc->need_ecne)
902                 return NULL;
903 
904         /* Send ECNE if needed.
905          * Not being able to allocate a chunk here is not deadly.
906          */
907         return sctp_make_ecne(asoc, asoc->last_ecne_tsn);
908 }
909 
910 /*
911  * Find which transport this TSN was sent on.
912  */
913 struct sctp_transport *sctp_assoc_lookup_tsn(struct sctp_association *asoc,
914                                              __u32 tsn)
915 {
916         struct sctp_transport *active;
917         struct sctp_transport *match;
918         struct sctp_transport *transport;
919         struct sctp_chunk *chunk;
920         __be32 key = htonl(tsn);
921 
922         match = NULL;
923 
924         /*
925          * FIXME: In general, find a more efficient data structure for
926          * searching.
927          */
928 
929         /*
930          * The general strategy is to search each transport's transmitted
931          * list.   Return which transport this TSN lives on.
932          *
933          * Let's be hopeful and check the active_path first.
934          * Another optimization would be to know if there is only one
935          * outbound path and not have to look for the TSN at all.
936          *
937          */
938 
939         active = asoc->peer.active_path;
940 
941         list_for_each_entry(chunk, &active->transmitted,
942                         transmitted_list) {
943 
944                 if (key == chunk->subh.data_hdr->tsn) {
945                         match = active;
946                         goto out;
947                 }
948         }
949 
950         /* If not found, go search all the other transports. */
951         list_for_each_entry(transport, &asoc->peer.transport_addr_list,
952                         transports) {
953 
954                 if (transport == active)
955                         continue;
956                 list_for_each_entry(chunk, &transport->transmitted,
957                                 transmitted_list) {
958                         if (key == chunk->subh.data_hdr->tsn) {
959                                 match = transport;
960                                 goto out;
961                         }
962                 }
963         }
964 out:
965         return match;
966 }
967 
968 /* Is this the association we are looking for? */
969 struct sctp_transport *sctp_assoc_is_match(struct sctp_association *asoc,
970                                            struct net *net,
971                                            const union sctp_addr *laddr,
972                                            const union sctp_addr *paddr)
973 {
974         struct sctp_transport *transport;
975 
976         if ((htons(asoc->base.bind_addr.port) == laddr->v4.sin_port) &&
977             (htons(asoc->peer.port) == paddr->v4.sin_port) &&
978             net_eq(sock_net(asoc->base.sk), net)) {
979                 transport = sctp_assoc_lookup_paddr(asoc, paddr);
980                 if (!transport)
981                         goto out;
982 
983                 if (sctp_bind_addr_match(&asoc->base.bind_addr, laddr,
984                                          sctp_sk(asoc->base.sk)))
985                         goto out;
986         }
987         transport = NULL;
988 
989 out:
990         return transport;
991 }
992 
993 /* Do delayed input processing.  This is scheduled by sctp_rcv(). */
994 static void sctp_assoc_bh_rcv(struct work_struct *work)
995 {
996         struct sctp_association *asoc =
997                 container_of(work, struct sctp_association,
998                              base.inqueue.immediate);
999         struct net *net = sock_net(asoc->base.sk);
1000         struct sctp_endpoint *ep;
1001         struct sctp_chunk *chunk;
1002         struct sctp_inq *inqueue;
1003         int state;
1004         sctp_subtype_t subtype;
1005         int error = 0;
1006 
1007         /* The association should be held so we should be safe. */
1008         ep = asoc->ep;
1009 
1010         inqueue = &asoc->base.inqueue;
1011         sctp_association_hold(asoc);
1012         while (NULL != (chunk = sctp_inq_pop(inqueue))) {
1013                 state = asoc->state;
1014                 subtype = SCTP_ST_CHUNK(chunk->chunk_hdr->type);
1015 
1016                 /* SCTP-AUTH, Section 6.3:
1017                  *    The receiver has a list of chunk types which it expects
1018                  *    to be received only after an AUTH-chunk.  This list has
1019                  *    been sent to the peer during the association setup.  It
1020                  *    MUST silently discard these chunks if they are not placed
1021                  *    after an AUTH chunk in the packet.
1022                  */
1023                 if (sctp_auth_recv_cid(subtype.chunk, asoc) && !chunk->auth)
1024                         continue;
1025 
1026                 /* Remember where the last DATA chunk came from so we
1027                  * know where to send the SACK.
1028                  */
1029                 if (sctp_chunk_is_data(chunk))
1030                         asoc->peer.last_data_from = chunk->transport;
1031                 else {
1032                         SCTP_INC_STATS(net, SCTP_MIB_INCTRLCHUNKS);
1033                         asoc->stats.ictrlchunks++;
1034                         if (chunk->chunk_hdr->type == SCTP_CID_SACK)
1035                                 asoc->stats.isacks++;
1036                 }
1037 
1038                 if (chunk->transport)
1039                         chunk->transport->last_time_heard = ktime_get();
1040 
1041                 /* Run through the state machine. */
1042                 error = sctp_do_sm(net, SCTP_EVENT_T_CHUNK, subtype,
1043                                    state, ep, asoc, chunk, GFP_ATOMIC);
1044 
1045                 /* Check to see if the association is freed in response to
1046                  * the incoming chunk.  If so, get out of the while loop.
1047                  */
1048                 if (asoc->base.dead)
1049                         break;
1050 
1051                 /* If there is an error on chunk, discard this packet. */
1052                 if (error && chunk)
1053                         chunk->pdiscard = 1;
1054         }
1055         sctp_association_put(asoc);
1056 }
1057 
1058 /* This routine moves an association from its old sk to a new sk.  */
1059 void sctp_assoc_migrate(struct sctp_association *assoc, struct sock *newsk)
1060 {
1061         struct sctp_sock *newsp = sctp_sk(newsk);
1062         struct sock *oldsk = assoc->base.sk;
1063 
1064         /* Delete the association from the old endpoint's list of
1065          * associations.
1066          */
1067         list_del_init(&assoc->asocs);
1068 
1069         /* Decrement the backlog value for a TCP-style socket. */
1070         if (sctp_style(oldsk, TCP))
1071                 oldsk->sk_ack_backlog--;
1072 
1073         /* Release references to the old endpoint and the sock.  */
1074         sctp_endpoint_put(assoc->ep);
1075         sock_put(assoc->base.sk);
1076 
1077         /* Get a reference to the new endpoint.  */
1078         assoc->ep = newsp->ep;
1079         sctp_endpoint_hold(assoc->ep);
1080 
1081         /* Get a reference to the new sock.  */
1082         assoc->base.sk = newsk;
1083         sock_hold(assoc->base.sk);
1084 
1085         /* Add the association to the new endpoint's list of associations.  */
1086         sctp_endpoint_add_asoc(newsp->ep, assoc);
1087 }
1088 
1089 /* Update an association (possibly from unexpected COOKIE-ECHO processing).  */
1090 void sctp_assoc_update(struct sctp_association *asoc,
1091                        struct sctp_association *new)
1092 {
1093         struct sctp_transport *trans;
1094         struct list_head *pos, *temp;
1095 
1096         /* Copy in new parameters of peer. */
1097         asoc->c = new->c;
1098         asoc->peer.rwnd = new->peer.rwnd;
1099         asoc->peer.sack_needed = new->peer.sack_needed;
1100         asoc->peer.auth_capable = new->peer.auth_capable;
1101         asoc->peer.i = new->peer.i;
1102         sctp_tsnmap_init(&asoc->peer.tsn_map, SCTP_TSN_MAP_INITIAL,
1103                          asoc->peer.i.initial_tsn, GFP_ATOMIC);
1104 
1105         /* Remove any peer addresses not present in the new association. */
1106         list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
1107                 trans = list_entry(pos, struct sctp_transport, transports);
1108                 if (!sctp_assoc_lookup_paddr(new, &trans->ipaddr)) {
1109                         sctp_assoc_rm_peer(asoc, trans);
1110                         continue;
1111                 }
1112 
1113                 if (asoc->state >= SCTP_STATE_ESTABLISHED)
1114                         sctp_transport_reset(trans);
1115         }
1116 
1117         /* If the case is A (association restart), use
1118          * initial_tsn as next_tsn. If the case is B, use
1119          * current next_tsn in case data sent to peer
1120          * has been discarded and needs retransmission.
1121          */
1122         if (asoc->state >= SCTP_STATE_ESTABLISHED) {
1123                 asoc->next_tsn = new->next_tsn;
1124                 asoc->ctsn_ack_point = new->ctsn_ack_point;
1125                 asoc->adv_peer_ack_point = new->adv_peer_ack_point;
1126 
1127                 /* Reinitialize SSN for both local streams
1128                  * and peer's streams.
1129                  */
1130                 sctp_ssnmap_clear(asoc->ssnmap);
1131 
1132                 /* Flush the ULP reassembly and ordered queue.
1133                  * Any data there will now be stale and will
1134                  * cause problems.
1135                  */
1136                 sctp_ulpq_flush(&asoc->ulpq);
1137 
1138                 /* reset the overall association error count so
1139                  * that the restarted association doesn't get torn
1140                  * down on the next retransmission timer.
1141                  */
1142                 asoc->overall_error_count = 0;
1143 
1144         } else {
1145                 /* Add any peer addresses from the new association. */
1146                 list_for_each_entry(trans, &new->peer.transport_addr_list,
1147                                 transports) {
1148                         if (!sctp_assoc_lookup_paddr(asoc, &trans->ipaddr))
1149                                 sctp_assoc_add_peer(asoc, &trans->ipaddr,
1150                                                     GFP_ATOMIC, trans->state);
1151                 }
1152 
1153                 asoc->ctsn_ack_point = asoc->next_tsn - 1;
1154                 asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
1155                 if (!asoc->ssnmap) {
1156                         /* Move the ssnmap. */
1157                         asoc->ssnmap = new->ssnmap;
1158                         new->ssnmap = NULL;
1159                 }
1160 
1161                 if (!asoc->assoc_id) {
1162                         /* get a new association id since we don't have one
1163                          * yet.
1164                          */
1165                         sctp_assoc_set_id(asoc, GFP_ATOMIC);
1166                 }
1167         }
1168 
1169         /* SCTP-AUTH: Save the peer parameters from the new associations
1170          * and also move the association shared keys over
1171          */
1172         kfree(asoc->peer.peer_random);
1173         asoc->peer.peer_random = new->peer.peer_random;
1174         new->peer.peer_random = NULL;
1175 
1176         kfree(asoc->peer.peer_chunks);
1177         asoc->peer.peer_chunks = new->peer.peer_chunks;
1178         new->peer.peer_chunks = NULL;
1179 
1180         kfree(asoc->peer.peer_hmacs);
1181         asoc->peer.peer_hmacs = new->peer.peer_hmacs;
1182         new->peer.peer_hmacs = NULL;
1183 
1184         sctp_auth_asoc_init_active_key(asoc, GFP_ATOMIC);
1185 }
1186 
1187 /* Update the retran path for sending a retransmitted packet.
1188  * See also RFC4960, 6.4. Multi-Homed SCTP Endpoints:
1189  *
1190  *   When there is outbound data to send and the primary path
1191  *   becomes inactive (e.g., due to failures), or where the
1192  *   SCTP user explicitly requests to send data to an
1193  *   inactive destination transport address, before reporting
1194  *   an error to its ULP, the SCTP endpoint should try to send
1195  *   the data to an alternate active destination transport
1196  *   address if one exists.
1197  *
1198  *   When retransmitting data that timed out, if the endpoint
1199  *   is multihomed, it should consider each source-destination
1200  *   address pair in its retransmission selection policy.
1201  *   When retransmitting timed-out data, the endpoint should
1202  *   attempt to pick the most divergent source-destination
1203  *   pair from the original source-destination pair to which
1204  *   the packet was transmitted.
1205  *
1206  *   Note: Rules for picking the most divergent source-destination
1207  *   pair are an implementation decision and are not specified
1208  *   within this document.
1209  *
1210  * Our basic strategy is to round-robin transports in priorities
1211  * according to sctp_state_prio_map[] e.g., if no such
1212  * transport with state SCTP_ACTIVE exists, round-robin through
1213  * SCTP_UNKNOWN, etc. You get the picture.
1214  */
1215 static const u8 sctp_trans_state_to_prio_map[] = {
1216         [SCTP_ACTIVE]   = 3,    /* best case */
1217         [SCTP_UNKNOWN]  = 2,
1218         [SCTP_PF]       = 1,
1219         [SCTP_INACTIVE] = 0,    /* worst case */
1220 };
1221 
1222 static u8 sctp_trans_score(const struct sctp_transport *trans)
1223 {
1224         return sctp_trans_state_to_prio_map[trans->state];
1225 }
1226 
1227 static struct sctp_transport *sctp_trans_elect_tie(struct sctp_transport *trans1,
1228                                                    struct sctp_transport *trans2)
1229 {
1230         if (trans1->error_count > trans2->error_count) {
1231                 return trans2;
1232         } else if (trans1->error_count == trans2->error_count &&
1233                    ktime_after(trans2->last_time_heard,
1234                                trans1->last_time_heard)) {
1235                 return trans2;
1236         } else {
1237                 return trans1;
1238         }
1239 }
1240 
1241 static struct sctp_transport *sctp_trans_elect_best(struct sctp_transport *curr,
1242                                                     struct sctp_transport *best)
1243 {
1244         u8 score_curr, score_best;
1245 
1246         if (best == NULL || curr == best)
1247                 return curr;
1248 
1249         score_curr = sctp_trans_score(curr);
1250         score_best = sctp_trans_score(best);
1251 
1252         /* First, try a score-based selection if both transport states
1253          * differ. If we're in a tie, lets try to make a more clever
1254          * decision here based on error counts and last time heard.
1255          */
1256         if (score_curr > score_best)
1257                 return curr;
1258         else if (score_curr == score_best)
1259                 return sctp_trans_elect_tie(curr, best);
1260         else
1261                 return best;
1262 }
1263 
1264 void sctp_assoc_update_retran_path(struct sctp_association *asoc)
1265 {
1266         struct sctp_transport *trans = asoc->peer.retran_path;
1267         struct sctp_transport *trans_next = NULL;
1268 
1269         /* We're done as we only have the one and only path. */
1270         if (asoc->peer.transport_count == 1)
1271                 return;
1272         /* If active_path and retran_path are the same and active,
1273          * then this is the only active path. Use it.
1274          */
1275         if (asoc->peer.active_path == asoc->peer.retran_path &&
1276             asoc->peer.active_path->state == SCTP_ACTIVE)
1277                 return;
1278 
1279         /* Iterate from retran_path's successor back to retran_path. */
1280         for (trans = list_next_entry(trans, transports); 1;
1281              trans = list_next_entry(trans, transports)) {
1282                 /* Manually skip the head element. */
1283                 if (&trans->transports == &asoc->peer.transport_addr_list)
1284                         continue;
1285                 if (trans->state == SCTP_UNCONFIRMED)
1286                         continue;
1287                 trans_next = sctp_trans_elect_best(trans, trans_next);
1288                 /* Active is good enough for immediate return. */
1289                 if (trans_next->state == SCTP_ACTIVE)
1290                         break;
1291                 /* We've reached the end, time to update path. */
1292                 if (trans == asoc->peer.retran_path)
1293                         break;
1294         }
1295 
1296         asoc->peer.retran_path = trans_next;
1297 
1298         pr_debug("%s: association:%p updated new path to addr:%pISpc\n",
1299                  __func__, asoc, &asoc->peer.retran_path->ipaddr.sa);
1300 }
1301 
1302 static void sctp_select_active_and_retran_path(struct sctp_association *asoc)
1303 {
1304         struct sctp_transport *trans, *trans_pri = NULL, *trans_sec = NULL;
1305         struct sctp_transport *trans_pf = NULL;
1306 
1307         /* Look for the two most recently used active transports. */
1308         list_for_each_entry(trans, &asoc->peer.transport_addr_list,
1309                             transports) {
1310                 /* Skip uninteresting transports. */
1311                 if (trans->state == SCTP_INACTIVE ||
1312                     trans->state == SCTP_UNCONFIRMED)
1313                         continue;
1314                 /* Keep track of the best PF transport from our
1315                  * list in case we don't find an active one.
1316                  */
1317                 if (trans->state == SCTP_PF) {
1318                         trans_pf = sctp_trans_elect_best(trans, trans_pf);
1319                         continue;
1320                 }
1321                 /* For active transports, pick the most recent ones. */
1322                 if (trans_pri == NULL ||
1323                     ktime_after(trans->last_time_heard,
1324                                 trans_pri->last_time_heard)) {
1325                         trans_sec = trans_pri;
1326                         trans_pri = trans;
1327                 } else if (trans_sec == NULL ||
1328                            ktime_after(trans->last_time_heard,
1329                                        trans_sec->last_time_heard)) {
1330                         trans_sec = trans;
1331                 }
1332         }
1333 
1334         /* RFC 2960 6.4 Multi-Homed SCTP Endpoints
1335          *
1336          * By default, an endpoint should always transmit to the primary
1337          * path, unless the SCTP user explicitly specifies the
1338          * destination transport address (and possibly source transport
1339          * address) to use. [If the primary is active but not most recent,
1340          * bump the most recently used transport.]
1341          */
1342         if ((asoc->peer.primary_path->state == SCTP_ACTIVE ||
1343              asoc->peer.primary_path->state == SCTP_UNKNOWN) &&
1344              asoc->peer.primary_path != trans_pri) {
1345                 trans_sec = trans_pri;
1346                 trans_pri = asoc->peer.primary_path;
1347         }
1348 
1349         /* We did not find anything useful for a possible retransmission
1350          * path; either primary path that we found is the the same as
1351          * the current one, or we didn't generally find an active one.
1352          */
1353         if (trans_sec == NULL)
1354                 trans_sec = trans_pri;
1355 
1356         /* If we failed to find a usable transport, just camp on the
1357          * active or pick a PF iff it's the better choice.
1358          */
1359         if (trans_pri == NULL) {
1360                 trans_pri = sctp_trans_elect_best(asoc->peer.active_path, trans_pf);
1361                 trans_sec = trans_pri;
1362         }
1363 
1364         /* Set the active and retran transports. */
1365         asoc->peer.active_path = trans_pri;
1366         asoc->peer.retran_path = trans_sec;
1367 }
1368 
1369 struct sctp_transport *
1370 sctp_assoc_choose_alter_transport(struct sctp_association *asoc,
1371                                   struct sctp_transport *last_sent_to)
1372 {
1373         /* If this is the first time packet is sent, use the active path,
1374          * else use the retran path. If the last packet was sent over the
1375          * retran path, update the retran path and use it.
1376          */
1377         if (last_sent_to == NULL) {
1378                 return asoc->peer.active_path;
1379         } else {
1380                 if (last_sent_to == asoc->peer.retran_path)
1381                         sctp_assoc_update_retran_path(asoc);
1382 
1383                 return asoc->peer.retran_path;
1384         }
1385 }
1386 
1387 /* Update the association's pmtu and frag_point by going through all the
1388  * transports. This routine is called when a transport's PMTU has changed.
1389  */
1390 void sctp_assoc_sync_pmtu(struct sock *sk, struct sctp_association *asoc)
1391 {
1392         struct sctp_transport *t;
1393         __u32 pmtu = 0;
1394 
1395         if (!asoc)
1396                 return;
1397 
1398         /* Get the lowest pmtu of all the transports. */
1399         list_for_each_entry(t, &asoc->peer.transport_addr_list,
1400                                 transports) {
1401                 if (t->pmtu_pending && t->dst) {
1402                         sctp_transport_update_pmtu(sk, t, dst_mtu(t->dst));
1403                         t->pmtu_pending = 0;
1404                 }
1405                 if (!pmtu || (t->pathmtu < pmtu))
1406                         pmtu = t->pathmtu;
1407         }
1408 
1409         if (pmtu) {
1410                 asoc->pathmtu = pmtu;
1411                 asoc->frag_point = sctp_frag_point(asoc, pmtu);
1412         }
1413 
1414         pr_debug("%s: asoc:%p, pmtu:%d, frag_point:%d\n", __func__, asoc,
1415                  asoc->pathmtu, asoc->frag_point);
1416 }
1417 
1418 /* Should we send a SACK to update our peer? */
1419 static inline bool sctp_peer_needs_update(struct sctp_association *asoc)
1420 {
1421         struct net *net = sock_net(asoc->base.sk);
1422         switch (asoc->state) {
1423         case SCTP_STATE_ESTABLISHED:
1424         case SCTP_STATE_SHUTDOWN_PENDING:
1425         case SCTP_STATE_SHUTDOWN_RECEIVED:
1426         case SCTP_STATE_SHUTDOWN_SENT:
1427                 if ((asoc->rwnd > asoc->a_rwnd) &&
1428                     ((asoc->rwnd - asoc->a_rwnd) >= max_t(__u32,
1429                            (asoc->base.sk->sk_rcvbuf >> net->sctp.rwnd_upd_shift),
1430                            asoc->pathmtu)))
1431                         return true;
1432                 break;
1433         default:
1434                 break;
1435         }
1436         return false;
1437 }
1438 
1439 /* Increase asoc's rwnd by len and send any window update SACK if needed. */
1440 void sctp_assoc_rwnd_increase(struct sctp_association *asoc, unsigned int len)
1441 {
1442         struct sctp_chunk *sack;
1443         struct timer_list *timer;
1444 
1445         if (asoc->rwnd_over) {
1446                 if (asoc->rwnd_over >= len) {
1447                         asoc->rwnd_over -= len;
1448                 } else {
1449                         asoc->rwnd += (len - asoc->rwnd_over);
1450                         asoc->rwnd_over = 0;
1451                 }
1452         } else {
1453                 asoc->rwnd += len;
1454         }
1455 
1456         /* If we had window pressure, start recovering it
1457          * once our rwnd had reached the accumulated pressure
1458          * threshold.  The idea is to recover slowly, but up
1459          * to the initial advertised window.
1460          */
1461         if (asoc->rwnd_press && asoc->rwnd >= asoc->rwnd_press) {
1462                 int change = min(asoc->pathmtu, asoc->rwnd_press);
1463                 asoc->rwnd += change;
1464                 asoc->rwnd_press -= change;
1465         }
1466 
1467         pr_debug("%s: asoc:%p rwnd increased by %d to (%u, %u) - %u\n",
1468                  __func__, asoc, len, asoc->rwnd, asoc->rwnd_over,
1469                  asoc->a_rwnd);
1470 
1471         /* Send a window update SACK if the rwnd has increased by at least the
1472          * minimum of the association's PMTU and half of the receive buffer.
1473          * The algorithm used is similar to the one described in
1474          * Section 4.2.3.3 of RFC 1122.
1475          */
1476         if (sctp_peer_needs_update(asoc)) {
1477                 asoc->a_rwnd = asoc->rwnd;
1478 
1479                 pr_debug("%s: sending window update SACK- asoc:%p rwnd:%u "
1480                          "a_rwnd:%u\n", __func__, asoc, asoc->rwnd,
1481                          asoc->a_rwnd);
1482 
1483                 sack = sctp_make_sack(asoc);
1484                 if (!sack)
1485                         return;
1486 
1487                 asoc->peer.sack_needed = 0;
1488 
1489                 sctp_outq_tail(&asoc->outqueue, sack);
1490 
1491                 /* Stop the SACK timer.  */
1492                 timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK];
1493                 if (del_timer(timer))
1494                         sctp_association_put(asoc);
1495         }
1496 }
1497 
1498 /* Decrease asoc's rwnd by len. */
1499 void sctp_assoc_rwnd_decrease(struct sctp_association *asoc, unsigned int len)
1500 {
1501         int rx_count;
1502         int over = 0;
1503 
1504         if (unlikely(!asoc->rwnd || asoc->rwnd_over))
1505                 pr_debug("%s: association:%p has asoc->rwnd:%u, "
1506                          "asoc->rwnd_over:%u!\n", __func__, asoc,
1507                          asoc->rwnd, asoc->rwnd_over);
1508 
1509         if (asoc->ep->rcvbuf_policy)
1510                 rx_count = atomic_read(&asoc->rmem_alloc);
1511         else
1512                 rx_count = atomic_read(&asoc->base.sk->sk_rmem_alloc);
1513 
1514         /* If we've reached or overflowed our receive buffer, announce
1515          * a 0 rwnd if rwnd would still be positive.  Store the
1516          * the potential pressure overflow so that the window can be restored
1517          * back to original value.
1518          */
1519         if (rx_count >= asoc->base.sk->sk_rcvbuf)
1520                 over = 1;
1521 
1522         if (asoc->rwnd >= len) {
1523                 asoc->rwnd -= len;
1524                 if (over) {
1525                         asoc->rwnd_press += asoc->rwnd;
1526                         asoc->rwnd = 0;
1527                 }
1528         } else {
1529                 asoc->rwnd_over = len - asoc->rwnd;
1530                 asoc->rwnd = 0;
1531         }
1532 
1533         pr_debug("%s: asoc:%p rwnd decreased by %d to (%u, %u, %u)\n",
1534                  __func__, asoc, len, asoc->rwnd, asoc->rwnd_over,
1535                  asoc->rwnd_press);
1536 }
1537 
1538 /* Build the bind address list for the association based on info from the
1539  * local endpoint and the remote peer.
1540  */
1541 int sctp_assoc_set_bind_addr_from_ep(struct sctp_association *asoc,
1542                                      sctp_scope_t scope, gfp_t gfp)
1543 {
1544         int flags;
1545 
1546         /* Use scoping rules to determine the subset of addresses from
1547          * the endpoint.
1548          */
1549         flags = (PF_INET6 == asoc->base.sk->sk_family) ? SCTP_ADDR6_ALLOWED : 0;
1550         if (asoc->peer.ipv4_address)
1551                 flags |= SCTP_ADDR4_PEERSUPP;
1552         if (asoc->peer.ipv6_address)
1553                 flags |= SCTP_ADDR6_PEERSUPP;
1554 
1555         return sctp_bind_addr_copy(sock_net(asoc->base.sk),
1556                                    &asoc->base.bind_addr,
1557                                    &asoc->ep->base.bind_addr,
1558                                    scope, gfp, flags);
1559 }
1560 
1561 /* Build the association's bind address list from the cookie.  */
1562 int sctp_assoc_set_bind_addr_from_cookie(struct sctp_association *asoc,
1563                                          struct sctp_cookie *cookie,
1564                                          gfp_t gfp)
1565 {
1566         int var_size2 = ntohs(cookie->peer_init->chunk_hdr.length);
1567         int var_size3 = cookie->raw_addr_list_len;
1568         __u8 *raw = (__u8 *)cookie->peer_init + var_size2;
1569 
1570         return sctp_raw_to_bind_addrs(&asoc->base.bind_addr, raw, var_size3,
1571                                       asoc->ep->base.bind_addr.port, gfp);
1572 }
1573 
1574 /* Lookup laddr in the bind address list of an association. */
1575 int sctp_assoc_lookup_laddr(struct sctp_association *asoc,
1576                             const union sctp_addr *laddr)
1577 {
1578         int found = 0;
1579 
1580         if ((asoc->base.bind_addr.port == ntohs(laddr->v4.sin_port)) &&
1581             sctp_bind_addr_match(&asoc->base.bind_addr, laddr,
1582                                  sctp_sk(asoc->base.sk)))
1583                 found = 1;
1584 
1585         return found;
1586 }
1587 
1588 /* Set an association id for a given association */
1589 int sctp_assoc_set_id(struct sctp_association *asoc, gfp_t gfp)
1590 {
1591         bool preload = !!(gfp & __GFP_WAIT);
1592         int ret;
1593 
1594         /* If the id is already assigned, keep it. */
1595         if (asoc->assoc_id)
1596                 return 0;
1597 
1598         if (preload)
1599                 idr_preload(gfp);
1600         spin_lock_bh(&sctp_assocs_id_lock);
1601         /* 0 is not a valid assoc_id, must be >= 1 */
1602         ret = idr_alloc_cyclic(&sctp_assocs_id, asoc, 1, 0, GFP_NOWAIT);
1603         spin_unlock_bh(&sctp_assocs_id_lock);
1604         if (preload)
1605                 idr_preload_end();
1606         if (ret < 0)
1607                 return ret;
1608 
1609         asoc->assoc_id = (sctp_assoc_t)ret;
1610         return 0;
1611 }
1612 
1613 /* Free the ASCONF queue */
1614 static void sctp_assoc_free_asconf_queue(struct sctp_association *asoc)
1615 {
1616         struct sctp_chunk *asconf;
1617         struct sctp_chunk *tmp;
1618 
1619         list_for_each_entry_safe(asconf, tmp, &asoc->addip_chunk_list, list) {
1620                 list_del_init(&asconf->list);
1621                 sctp_chunk_free(asconf);
1622         }
1623 }
1624 
1625 /* Free asconf_ack cache */
1626 static void sctp_assoc_free_asconf_acks(struct sctp_association *asoc)
1627 {
1628         struct sctp_chunk *ack;
1629         struct sctp_chunk *tmp;
1630 
1631         list_for_each_entry_safe(ack, tmp, &asoc->asconf_ack_list,
1632                                 transmitted_list) {
1633                 list_del_init(&ack->transmitted_list);
1634                 sctp_chunk_free(ack);
1635         }
1636 }
1637 
1638 /* Clean up the ASCONF_ACK queue */
1639 void sctp_assoc_clean_asconf_ack_cache(const struct sctp_association *asoc)
1640 {
1641         struct sctp_chunk *ack;
1642         struct sctp_chunk *tmp;
1643 
1644         /* We can remove all the entries from the queue up to
1645          * the "Peer-Sequence-Number".
1646          */
1647         list_for_each_entry_safe(ack, tmp, &asoc->asconf_ack_list,
1648                                 transmitted_list) {
1649                 if (ack->subh.addip_hdr->serial ==
1650                                 htonl(asoc->peer.addip_serial))
1651                         break;
1652 
1653                 list_del_init(&ack->transmitted_list);
1654                 sctp_chunk_free(ack);
1655         }
1656 }
1657 
1658 /* Find the ASCONF_ACK whose serial number matches ASCONF */
1659 struct sctp_chunk *sctp_assoc_lookup_asconf_ack(
1660                                         const struct sctp_association *asoc,
1661                                         __be32 serial)
1662 {
1663         struct sctp_chunk *ack;
1664 
1665         /* Walk through the list of cached ASCONF-ACKs and find the
1666          * ack chunk whose serial number matches that of the request.
1667          */
1668         list_for_each_entry(ack, &asoc->asconf_ack_list, transmitted_list) {
1669                 if (sctp_chunk_pending(ack))
1670                         continue;
1671                 if (ack->subh.addip_hdr->serial == serial) {
1672                         sctp_chunk_hold(ack);
1673                         return ack;
1674                 }
1675         }
1676 
1677         return NULL;
1678 }
1679 
1680 void sctp_asconf_queue_teardown(struct sctp_association *asoc)
1681 {
1682         /* Free any cached ASCONF_ACK chunk. */
1683         sctp_assoc_free_asconf_acks(asoc);
1684 
1685         /* Free the ASCONF queue. */
1686         sctp_assoc_free_asconf_queue(asoc);
1687 
1688         /* Free any cached ASCONF chunk. */
1689         if (asoc->addip_last_asconf)
1690                 sctp_chunk_free(asoc->addip_last_asconf);
1691 }
1692 

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