~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

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

Version: ~ [ linux-5.5-rc7 ] ~ [ linux-5.4.13 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.97 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.166 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.210 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.210 ] ~ [ 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-3.16.81 ] ~ [ 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 ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

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

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp