1 /* SCTP kernel implementation
2 * Copyright (c) 1999-2000 Cisco, Inc.
3 * Copyright (c) 1999-2001 Motorola, Inc.
4 * Copyright (c) 2001-2003 International Business Machines, Corp.
5 * Copyright (c) 2001 Intel Corp.
6 * Copyright (c) 2001 Nokia, Inc.
7 * Copyright (c) 2001 La Monte H.P. Yarroll
9 * This file is part of the SCTP kernel implementation
11 * These functions handle all input from the IP layer into SCTP.
13 * This SCTP implementation is free software;
14 * you can redistribute it and/or modify it under the terms of
15 * the GNU General Public License as published by
16 * the Free Software Foundation; either version 2, or (at your option)
19 * This SCTP implementation is distributed in the hope that it
20 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
21 * ************************
22 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
23 * See the GNU General Public License for more details.
25 * You should have received a copy of the GNU General Public License
26 * along with GNU CC; see the file COPYING. If not, see
27 * <http://www.gnu.org/licenses/>.
29 * Please send any bug reports or fixes you make to the
31 * lksctp developers <linux-sctp@vger.kernel.org>
33 * Written or modified by:
34 * La Monte H.P. Yarroll <piggy@acm.org>
35 * Karl Knutson <karl@athena.chicago.il.us>
36 * Xingang Guo <xingang.guo@intel.com>
37 * Jon Grimm <jgrimm@us.ibm.com>
38 * Hui Huang <hui.huang@nokia.com>
39 * Daisy Chang <daisyc@us.ibm.com>
40 * Sridhar Samudrala <sri@us.ibm.com>
41 * Ardelle Fan <ardelle.fan@intel.com>
44 #include <linux/types.h>
45 #include <linux/list.h> /* For struct list_head */
46 #include <linux/socket.h>
48 #include <linux/time.h> /* For struct timeval */
49 #include <linux/slab.h>
55 #include <net/sctp/sctp.h>
56 #include <net/sctp/sm.h>
57 #include <net/sctp/checksum.h>
58 #include <net/net_namespace.h>
60 /* Forward declarations for internal helpers. */
61 static int sctp_rcv_ootb(struct sk_buff *);
62 static struct sctp_association *__sctp_rcv_lookup(struct net *net,
64 const union sctp_addr *paddr,
65 const union sctp_addr *laddr,
66 struct sctp_transport **transportp);
67 static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(struct net *net,
68 const union sctp_addr *laddr);
69 static struct sctp_association *__sctp_lookup_association(
71 const union sctp_addr *local,
72 const union sctp_addr *peer,
73 struct sctp_transport **pt);
75 static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb);
78 /* Calculate the SCTP checksum of an SCTP packet. */
79 static inline int sctp_rcv_checksum(struct net *net, struct sk_buff *skb)
81 struct sctphdr *sh = sctp_hdr(skb);
82 __le32 cmp = sh->checksum;
83 __le32 val = sctp_compute_cksum(skb, 0);
86 /* CRC failure, dump it. */
87 SCTP_INC_STATS_BH(net, SCTP_MIB_CHECKSUMERRORS);
93 struct sctp_input_cb {
95 struct inet_skb_parm h4;
96 #if IS_ENABLED(CONFIG_IPV6)
97 struct inet6_skb_parm h6;
100 struct sctp_chunk *chunk;
102 #define SCTP_INPUT_CB(__skb) ((struct sctp_input_cb *)&((__skb)->cb[0]))
105 * This is the routine which IP calls when receiving an SCTP packet.
107 int sctp_rcv(struct sk_buff *skb)
110 struct sctp_association *asoc;
111 struct sctp_endpoint *ep = NULL;
112 struct sctp_ep_common *rcvr;
113 struct sctp_transport *transport = NULL;
114 struct sctp_chunk *chunk;
117 union sctp_addr dest;
120 struct net *net = dev_net(skb->dev);
122 if (skb->pkt_type != PACKET_HOST)
125 SCTP_INC_STATS_BH(net, SCTP_MIB_INSCTPPACKS);
127 if (skb_linearize(skb))
132 /* Pull up the IP and SCTP headers. */
133 __skb_pull(skb, skb_transport_offset(skb));
134 if (skb->len < sizeof(struct sctphdr))
137 skb->csum_valid = 0; /* Previous value not applicable */
138 if (skb_csum_unnecessary(skb))
139 __skb_decr_checksum_unnecessary(skb);
140 else if (!sctp_checksum_disable && sctp_rcv_checksum(net, skb) < 0)
144 skb_pull(skb, sizeof(struct sctphdr));
146 /* Make sure we at least have chunk headers worth of data left. */
147 if (skb->len < sizeof(struct sctp_chunkhdr))
150 family = ipver2af(ip_hdr(skb)->version);
151 af = sctp_get_af_specific(family);
155 /* Initialize local addresses for lookups. */
156 af->from_skb(&src, skb, 1);
157 af->from_skb(&dest, skb, 0);
159 /* If the packet is to or from a non-unicast address,
160 * silently discard the packet.
162 * This is not clearly defined in the RFC except in section
163 * 8.4 - OOTB handling. However, based on the book "Stream Control
164 * Transmission Protocol" 2.1, "It is important to note that the
165 * IP address of an SCTP transport address must be a routable
166 * unicast address. In other words, IP multicast addresses and
167 * IP broadcast addresses cannot be used in an SCTP transport
170 if (!af->addr_valid(&src, NULL, skb) ||
171 !af->addr_valid(&dest, NULL, skb))
174 asoc = __sctp_rcv_lookup(net, skb, &src, &dest, &transport);
177 ep = __sctp_rcv_lookup_endpoint(net, &dest);
179 /* Retrieve the common input handling substructure. */
180 rcvr = asoc ? &asoc->base : &ep->base;
184 * If a frame arrives on an interface and the receiving socket is
185 * bound to another interface, via SO_BINDTODEVICE, treat it as OOTB
187 if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb))) {
189 sctp_association_put(asoc);
192 sctp_endpoint_put(ep);
195 sk = net->sctp.ctl_sock;
196 ep = sctp_sk(sk)->ep;
197 sctp_endpoint_hold(ep);
202 * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
203 * An SCTP packet is called an "out of the blue" (OOTB)
204 * packet if it is correctly formed, i.e., passed the
205 * receiver's checksum check, but the receiver is not
206 * able to identify the association to which this
210 if (sctp_rcv_ootb(skb)) {
211 SCTP_INC_STATS_BH(net, SCTP_MIB_OUTOFBLUES);
212 goto discard_release;
216 if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family))
217 goto discard_release;
220 if (sk_filter(sk, skb))
221 goto discard_release;
223 /* Create an SCTP packet structure. */
224 chunk = sctp_chunkify(skb, asoc, sk);
226 goto discard_release;
227 SCTP_INPUT_CB(skb)->chunk = chunk;
229 /* Remember what endpoint is to handle this packet. */
232 /* Remember the SCTP header. */
233 chunk->sctp_hdr = sh;
235 /* Set the source and destination addresses of the incoming chunk. */
236 sctp_init_addrs(chunk, &src, &dest);
238 /* Remember where we came from. */
239 chunk->transport = transport;
241 /* Acquire access to the sock lock. Note: We are safe from other
242 * bottom halves on this lock, but a user may be in the lock too,
243 * so check if it is busy.
247 if (sk != rcvr->sk) {
248 /* Our cached sk is different from the rcvr->sk. This is
249 * because migrate()/accept() may have moved the association
250 * to a new socket and released all the sockets. So now we
251 * are holding a lock on the old socket while the user may
252 * be doing something with the new socket. Switch our veiw
260 if (sock_owned_by_user(sk)) {
261 if (sctp_add_backlog(sk, skb)) {
263 sctp_chunk_free(chunk);
264 skb = NULL; /* sctp_chunk_free already freed the skb */
265 goto discard_release;
267 SCTP_INC_STATS_BH(net, SCTP_MIB_IN_PKT_BACKLOG);
269 SCTP_INC_STATS_BH(net, SCTP_MIB_IN_PKT_SOFTIRQ);
270 sctp_inq_push(&chunk->rcvr->inqueue, chunk);
275 /* Release the asoc/ep ref we took in the lookup calls. */
277 sctp_association_put(asoc);
279 sctp_endpoint_put(ep);
284 SCTP_INC_STATS_BH(net, SCTP_MIB_IN_PKT_DISCARDS);
289 /* Release the asoc/ep ref we took in the lookup calls. */
291 sctp_association_put(asoc);
293 sctp_endpoint_put(ep);
298 /* Process the backlog queue of the socket. Every skb on
299 * the backlog holds a ref on an association or endpoint.
300 * We hold this ref throughout the state machine to make
301 * sure that the structure we need is still around.
303 int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
305 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
306 struct sctp_inq *inqueue = &chunk->rcvr->inqueue;
307 struct sctp_ep_common *rcvr = NULL;
312 /* If the rcvr is dead then the association or endpoint
313 * has been deleted and we can safely drop the chunk
314 * and refs that we are holding.
317 sctp_chunk_free(chunk);
321 if (unlikely(rcvr->sk != sk)) {
322 /* In this case, the association moved from one socket to
323 * another. We are currently sitting on the backlog of the
324 * old socket, so we need to move.
325 * However, since we are here in the process context we
326 * need to take make sure that the user doesn't own
327 * the new socket when we process the packet.
328 * If the new socket is user-owned, queue the chunk to the
329 * backlog of the new socket without dropping any refs.
330 * Otherwise, we can safely push the chunk on the inqueue.
336 if (sock_owned_by_user(sk)) {
337 if (sk_add_backlog(sk, skb, sk->sk_rcvbuf))
338 sctp_chunk_free(chunk);
342 sctp_inq_push(inqueue, chunk);
346 /* If the chunk was backloged again, don't drop refs */
350 sctp_inq_push(inqueue, chunk);
354 /* Release the refs we took in sctp_add_backlog */
355 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
356 sctp_association_put(sctp_assoc(rcvr));
357 else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
358 sctp_endpoint_put(sctp_ep(rcvr));
365 static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb)
367 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
368 struct sctp_ep_common *rcvr = chunk->rcvr;
371 ret = sk_add_backlog(sk, skb, sk->sk_rcvbuf);
373 /* Hold the assoc/ep while hanging on the backlog queue.
374 * This way, we know structures we need will not disappear
377 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
378 sctp_association_hold(sctp_assoc(rcvr));
379 else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
380 sctp_endpoint_hold(sctp_ep(rcvr));
388 /* Handle icmp frag needed error. */
389 void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc,
390 struct sctp_transport *t, __u32 pmtu)
392 if (!t || (t->pathmtu <= pmtu))
395 if (sock_owned_by_user(sk)) {
396 asoc->pmtu_pending = 1;
401 if (t->param_flags & SPP_PMTUD_ENABLE) {
402 /* Update transports view of the MTU */
403 sctp_transport_update_pmtu(sk, t, pmtu);
405 /* Update association pmtu. */
406 sctp_assoc_sync_pmtu(sk, asoc);
409 /* Retransmit with the new pmtu setting.
410 * Normally, if PMTU discovery is disabled, an ICMP Fragmentation
411 * Needed will never be sent, but if a message was sent before
412 * PMTU discovery was disabled that was larger than the PMTU, it
413 * would not be fragmented, so it must be re-transmitted fragmented.
415 sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD);
418 void sctp_icmp_redirect(struct sock *sk, struct sctp_transport *t,
421 struct dst_entry *dst;
423 if (sock_owned_by_user(sk) || !t)
425 dst = sctp_transport_dst_check(t);
427 dst->ops->redirect(dst, sk, skb);
431 * SCTP Implementer's Guide, 2.37 ICMP handling procedures
433 * ICMP8) If the ICMP code is a "Unrecognized next header type encountered"
434 * or a "Protocol Unreachable" treat this message as an abort
435 * with the T bit set.
437 * This function sends an event to the state machine, which will abort the
441 void sctp_icmp_proto_unreachable(struct sock *sk,
442 struct sctp_association *asoc,
443 struct sctp_transport *t)
445 if (sock_owned_by_user(sk)) {
446 if (timer_pending(&t->proto_unreach_timer))
449 if (!mod_timer(&t->proto_unreach_timer,
451 sctp_transport_hold(t);
454 struct net *net = sock_net(sk);
456 pr_debug("%s: unrecognized next header type "
457 "encountered!\n", __func__);
459 if (del_timer(&t->proto_unreach_timer))
460 sctp_transport_put(t);
462 sctp_do_sm(net, SCTP_EVENT_T_OTHER,
463 SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH),
464 asoc->state, asoc->ep, asoc, t,
469 /* Common lookup code for icmp/icmpv6 error handler. */
470 struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *skb,
471 struct sctphdr *sctphdr,
472 struct sctp_association **app,
473 struct sctp_transport **tpp)
475 struct sctp_init_chunk *chunkhdr, _chunkhdr;
476 union sctp_addr saddr;
477 union sctp_addr daddr;
479 struct sock *sk = NULL;
480 struct sctp_association *asoc;
481 struct sctp_transport *transport = NULL;
482 __u32 vtag = ntohl(sctphdr->vtag);
484 *app = NULL; *tpp = NULL;
486 af = sctp_get_af_specific(family);
491 /* Initialize local addresses for lookups. */
492 af->from_skb(&saddr, skb, 1);
493 af->from_skb(&daddr, skb, 0);
495 /* Look for an association that matches the incoming ICMP error
498 asoc = __sctp_lookup_association(net, &saddr, &daddr, &transport);
504 /* RFC 4960, Appendix C. ICMP Handling
506 * ICMP6) An implementation MUST validate that the Verification Tag
507 * contained in the ICMP message matches the Verification Tag of
508 * the peer. If the Verification Tag is not 0 and does NOT
509 * match, discard the ICMP message. If it is 0 and the ICMP
510 * message contains enough bytes to verify that the chunk type is
511 * an INIT chunk and that the Initiate Tag matches the tag of the
512 * peer, continue with ICMP7. If the ICMP message is too short
513 * or the chunk type or the Initiate Tag does not match, silently
514 * discard the packet.
517 /* chunk header + first 4 octects of init header */
518 chunkhdr = skb_header_pointer(skb, skb_transport_offset(skb) +
519 sizeof(struct sctphdr),
520 sizeof(struct sctp_chunkhdr) +
521 sizeof(__be32), &_chunkhdr);
523 chunkhdr->chunk_hdr.type != SCTP_CID_INIT ||
524 ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag)
527 } else if (vtag != asoc->c.peer_vtag) {
533 /* If too many ICMPs get dropped on busy
534 * servers this needs to be solved differently.
536 if (sock_owned_by_user(sk))
537 NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
544 sctp_association_put(asoc);
548 /* Common cleanup code for icmp/icmpv6 error handler. */
549 void sctp_err_finish(struct sock *sk, struct sctp_association *asoc)
552 sctp_association_put(asoc);
556 * This routine is called by the ICMP module when it gets some
557 * sort of error condition. If err < 0 then the socket should
558 * be closed and the error returned to the user. If err > 0
559 * it's just the icmp type << 8 | icmp code. After adjustment
560 * header points to the first 8 bytes of the sctp header. We need
561 * to find the appropriate port.
563 * The locking strategy used here is very "optimistic". When
564 * someone else accesses the socket the ICMP is just dropped
565 * and for some paths there is no check at all.
566 * A more general error queue to queue errors for later handling
567 * is probably better.
570 void sctp_v4_err(struct sk_buff *skb, __u32 info)
572 const struct iphdr *iph = (const struct iphdr *)skb->data;
573 const int ihlen = iph->ihl * 4;
574 const int type = icmp_hdr(skb)->type;
575 const int code = icmp_hdr(skb)->code;
577 struct sctp_association *asoc = NULL;
578 struct sctp_transport *transport;
579 struct inet_sock *inet;
580 __u16 saveip, savesctp;
582 struct net *net = dev_net(skb->dev);
584 /* Fix up skb to look at the embedded net header. */
585 saveip = skb->network_header;
586 savesctp = skb->transport_header;
587 skb_reset_network_header(skb);
588 skb_set_transport_header(skb, ihlen);
589 sk = sctp_err_lookup(net, AF_INET, skb, sctp_hdr(skb), &asoc, &transport);
590 /* Put back, the original values. */
591 skb->network_header = saveip;
592 skb->transport_header = savesctp;
594 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
597 /* Warning: The sock lock is held. Remember to call
602 case ICMP_PARAMETERPROB:
605 case ICMP_DEST_UNREACH:
606 if (code > NR_ICMP_UNREACH)
609 /* PMTU discovery (RFC1191) */
610 if (ICMP_FRAG_NEEDED == code) {
611 sctp_icmp_frag_needed(sk, asoc, transport, info);
614 if (ICMP_PROT_UNREACH == code) {
615 sctp_icmp_proto_unreachable(sk, asoc,
620 err = icmp_err_convert[code].errno;
622 case ICMP_TIME_EXCEEDED:
623 /* Ignore any time exceeded errors due to fragment reassembly
626 if (ICMP_EXC_FRAGTIME == code)
632 sctp_icmp_redirect(sk, transport, skb);
633 /* Fall through to out_unlock. */
639 if (!sock_owned_by_user(sk) && inet->recverr) {
641 sk->sk_error_report(sk);
642 } else { /* Only an error on timeout */
643 sk->sk_err_soft = err;
647 sctp_err_finish(sk, asoc);
651 * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
653 * This function scans all the chunks in the OOTB packet to determine if
654 * the packet should be discarded right away. If a response might be needed
655 * for this packet, or, if further processing is possible, the packet will
656 * be queued to a proper inqueue for the next phase of handling.
659 * Return 0 - If further processing is needed.
660 * Return 1 - If the packet can be discarded right away.
662 static int sctp_rcv_ootb(struct sk_buff *skb)
667 ch = (sctp_chunkhdr_t *) skb->data;
669 /* Scan through all the chunks in the packet. */
671 /* Break out if chunk length is less then minimal. */
672 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
675 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
676 if (ch_end > skb_tail_pointer(skb))
679 /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the
680 * receiver MUST silently discard the OOTB packet and take no
683 if (SCTP_CID_ABORT == ch->type)
686 /* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE
687 * chunk, the receiver should silently discard the packet
688 * and take no further action.
690 if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type)
694 * This will discard packets with INIT chunk bundled as
695 * subsequent chunks in the packet. When INIT is first,
696 * the normal INIT processing will discard the chunk.
698 if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data)
701 ch = (sctp_chunkhdr_t *) ch_end;
702 } while (ch_end < skb_tail_pointer(skb));
710 /* Insert endpoint into the hash table. */
711 static void __sctp_hash_endpoint(struct sctp_endpoint *ep)
713 struct net *net = sock_net(ep->base.sk);
714 struct sctp_ep_common *epb;
715 struct sctp_hashbucket *head;
719 epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port);
720 head = &sctp_ep_hashtable[epb->hashent];
722 write_lock(&head->lock);
723 hlist_add_head(&epb->node, &head->chain);
724 write_unlock(&head->lock);
727 /* Add an endpoint to the hash. Local BH-safe. */
728 void sctp_hash_endpoint(struct sctp_endpoint *ep)
731 __sctp_hash_endpoint(ep);
735 /* Remove endpoint from the hash table. */
736 static void __sctp_unhash_endpoint(struct sctp_endpoint *ep)
738 struct net *net = sock_net(ep->base.sk);
739 struct sctp_hashbucket *head;
740 struct sctp_ep_common *epb;
744 epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port);
746 head = &sctp_ep_hashtable[epb->hashent];
748 write_lock(&head->lock);
749 hlist_del_init(&epb->node);
750 write_unlock(&head->lock);
753 /* Remove endpoint from the hash. Local BH-safe. */
754 void sctp_unhash_endpoint(struct sctp_endpoint *ep)
757 __sctp_unhash_endpoint(ep);
761 /* Look up an endpoint. */
762 static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(struct net *net,
763 const union sctp_addr *laddr)
765 struct sctp_hashbucket *head;
766 struct sctp_ep_common *epb;
767 struct sctp_endpoint *ep;
770 hash = sctp_ep_hashfn(net, ntohs(laddr->v4.sin_port));
771 head = &sctp_ep_hashtable[hash];
772 read_lock(&head->lock);
773 sctp_for_each_hentry(epb, &head->chain) {
775 if (sctp_endpoint_is_match(ep, net, laddr))
779 ep = sctp_sk(net->sctp.ctl_sock)->ep;
782 sctp_endpoint_hold(ep);
783 read_unlock(&head->lock);
787 /* Insert association into the hash table. */
788 static void __sctp_hash_established(struct sctp_association *asoc)
790 struct net *net = sock_net(asoc->base.sk);
791 struct sctp_ep_common *epb;
792 struct sctp_hashbucket *head;
796 /* Calculate which chain this entry will belong to. */
797 epb->hashent = sctp_assoc_hashfn(net, epb->bind_addr.port,
800 head = &sctp_assoc_hashtable[epb->hashent];
802 write_lock(&head->lock);
803 hlist_add_head(&epb->node, &head->chain);
804 write_unlock(&head->lock);
807 /* Add an association to the hash. Local BH-safe. */
808 void sctp_hash_established(struct sctp_association *asoc)
814 __sctp_hash_established(asoc);
818 /* Remove association from the hash table. */
819 static void __sctp_unhash_established(struct sctp_association *asoc)
821 struct net *net = sock_net(asoc->base.sk);
822 struct sctp_hashbucket *head;
823 struct sctp_ep_common *epb;
827 epb->hashent = sctp_assoc_hashfn(net, epb->bind_addr.port,
830 head = &sctp_assoc_hashtable[epb->hashent];
832 write_lock(&head->lock);
833 hlist_del_init(&epb->node);
834 write_unlock(&head->lock);
837 /* Remove association from the hash table. Local BH-safe. */
838 void sctp_unhash_established(struct sctp_association *asoc)
844 __sctp_unhash_established(asoc);
848 /* Look up an association. */
849 static struct sctp_association *__sctp_lookup_association(
851 const union sctp_addr *local,
852 const union sctp_addr *peer,
853 struct sctp_transport **pt)
855 struct sctp_hashbucket *head;
856 struct sctp_ep_common *epb;
857 struct sctp_association *asoc;
858 struct sctp_transport *transport;
861 /* Optimize here for direct hit, only listening connections can
862 * have wildcards anyways.
864 hash = sctp_assoc_hashfn(net, ntohs(local->v4.sin_port),
865 ntohs(peer->v4.sin_port));
866 head = &sctp_assoc_hashtable[hash];
867 read_lock(&head->lock);
868 sctp_for_each_hentry(epb, &head->chain) {
869 asoc = sctp_assoc(epb);
870 transport = sctp_assoc_is_match(asoc, net, local, peer);
875 read_unlock(&head->lock);
881 sctp_association_hold(asoc);
882 read_unlock(&head->lock);
886 /* Look up an association. BH-safe. */
888 struct sctp_association *sctp_lookup_association(struct net *net,
889 const union sctp_addr *laddr,
890 const union sctp_addr *paddr,
891 struct sctp_transport **transportp)
893 struct sctp_association *asoc;
896 asoc = __sctp_lookup_association(net, laddr, paddr, transportp);
902 /* Is there an association matching the given local and peer addresses? */
903 int sctp_has_association(struct net *net,
904 const union sctp_addr *laddr,
905 const union sctp_addr *paddr)
907 struct sctp_association *asoc;
908 struct sctp_transport *transport;
910 if ((asoc = sctp_lookup_association(net, laddr, paddr, &transport))) {
911 sctp_association_put(asoc);
919 * SCTP Implementors Guide, 2.18 Handling of address
920 * parameters within the INIT or INIT-ACK.
922 * D) When searching for a matching TCB upon reception of an INIT
923 * or INIT-ACK chunk the receiver SHOULD use not only the
924 * source address of the packet (containing the INIT or
925 * INIT-ACK) but the receiver SHOULD also use all valid
926 * address parameters contained within the chunk.
928 * 2.18.3 Solution description
930 * This new text clearly specifies to an implementor the need
931 * to look within the INIT or INIT-ACK. Any implementation that
932 * does not do this, may not be able to establish associations
933 * in certain circumstances.
936 static struct sctp_association *__sctp_rcv_init_lookup(struct net *net,
938 const union sctp_addr *laddr, struct sctp_transport **transportp)
940 struct sctp_association *asoc;
941 union sctp_addr addr;
942 union sctp_addr *paddr = &addr;
943 struct sctphdr *sh = sctp_hdr(skb);
944 union sctp_params params;
945 sctp_init_chunk_t *init;
946 struct sctp_transport *transport;
950 * This code will NOT touch anything inside the chunk--it is
951 * strictly READ-ONLY.
953 * RFC 2960 3 SCTP packet Format
955 * Multiple chunks can be bundled into one SCTP packet up to
956 * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN
957 * COMPLETE chunks. These chunks MUST NOT be bundled with any
958 * other chunk in a packet. See Section 6.10 for more details
962 /* Find the start of the TLVs and the end of the chunk. This is
963 * the region we search for address parameters.
965 init = (sctp_init_chunk_t *)skb->data;
967 /* Walk the parameters looking for embedded addresses. */
968 sctp_walk_params(params, init, init_hdr.params) {
970 /* Note: Ignoring hostname addresses. */
971 af = sctp_get_af_specific(param_type2af(params.p->type));
975 if (!af->from_addr_param(paddr, params.addr, sh->source, 0))
978 asoc = __sctp_lookup_association(net, laddr, paddr, &transport);
986 /* ADD-IP, Section 5.2
987 * When an endpoint receives an ASCONF Chunk from the remote peer
988 * special procedures may be needed to identify the association the
989 * ASCONF Chunk is associated with. To properly find the association
990 * the following procedures SHOULD be followed:
992 * D2) If the association is not found, use the address found in the
993 * Address Parameter TLV combined with the port number found in the
994 * SCTP common header. If found proceed to rule D4.
996 * D2-ext) If more than one ASCONF Chunks are packed together, use the
997 * address found in the ASCONF Address Parameter TLV of each of the
998 * subsequent ASCONF Chunks. If found, proceed to rule D4.
1000 static struct sctp_association *__sctp_rcv_asconf_lookup(
1002 sctp_chunkhdr_t *ch,
1003 const union sctp_addr *laddr,
1005 struct sctp_transport **transportp)
1007 sctp_addip_chunk_t *asconf = (struct sctp_addip_chunk *)ch;
1009 union sctp_addr_param *param;
1010 union sctp_addr paddr;
1012 if (ntohs(ch->length) < sizeof(*asconf) + sizeof(struct sctp_paramhdr))
1015 /* Skip over the ADDIP header and find the Address parameter */
1016 param = (union sctp_addr_param *)(asconf + 1);
1018 af = sctp_get_af_specific(param_type2af(param->p.type));
1022 if (af->from_addr_param(&paddr, param, peer_port, 0))
1025 return __sctp_lookup_association(net, laddr, &paddr, transportp);
1029 /* SCTP-AUTH, Section 6.3:
1030 * If the receiver does not find a STCB for a packet containing an AUTH
1031 * chunk as the first chunk and not a COOKIE-ECHO chunk as the second
1032 * chunk, it MUST use the chunks after the AUTH chunk to look up an existing
1035 * This means that any chunks that can help us identify the association need
1036 * to be looked at to find this association.
1038 static struct sctp_association *__sctp_rcv_walk_lookup(struct net *net,
1039 struct sk_buff *skb,
1040 const union sctp_addr *laddr,
1041 struct sctp_transport **transportp)
1043 struct sctp_association *asoc = NULL;
1044 sctp_chunkhdr_t *ch;
1046 unsigned int chunk_num = 1;
1049 /* Walk through the chunks looking for AUTH or ASCONF chunks
1050 * to help us find the association.
1052 ch = (sctp_chunkhdr_t *) skb->data;
1054 /* Break out if chunk length is less then minimal. */
1055 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
1058 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
1059 if (ch_end > skb_tail_pointer(skb))
1064 have_auth = chunk_num;
1067 case SCTP_CID_COOKIE_ECHO:
1068 /* If a packet arrives containing an AUTH chunk as
1069 * a first chunk, a COOKIE-ECHO chunk as the second
1070 * chunk, and possibly more chunks after them, and
1071 * the receiver does not have an STCB for that
1072 * packet, then authentication is based on
1073 * the contents of the COOKIE- ECHO chunk.
1075 if (have_auth == 1 && chunk_num == 2)
1079 case SCTP_CID_ASCONF:
1080 if (have_auth || net->sctp.addip_noauth)
1081 asoc = __sctp_rcv_asconf_lookup(
1083 sctp_hdr(skb)->source,
1092 ch = (sctp_chunkhdr_t *) ch_end;
1094 } while (ch_end + sizeof(*ch) < skb_tail_pointer(skb));
1100 * There are circumstances when we need to look inside the SCTP packet
1101 * for information to help us find the association. Examples
1102 * include looking inside of INIT/INIT-ACK chunks or after the AUTH
1105 static struct sctp_association *__sctp_rcv_lookup_harder(struct net *net,
1106 struct sk_buff *skb,
1107 const union sctp_addr *laddr,
1108 struct sctp_transport **transportp)
1110 sctp_chunkhdr_t *ch;
1112 ch = (sctp_chunkhdr_t *) skb->data;
1114 /* The code below will attempt to walk the chunk and extract
1115 * parameter information. Before we do that, we need to verify
1116 * that the chunk length doesn't cause overflow. Otherwise, we'll
1119 if (WORD_ROUND(ntohs(ch->length)) > skb->len)
1122 /* If this is INIT/INIT-ACK look inside the chunk too. */
1123 if (ch->type == SCTP_CID_INIT || ch->type == SCTP_CID_INIT_ACK)
1124 return __sctp_rcv_init_lookup(net, skb, laddr, transportp);
1126 return __sctp_rcv_walk_lookup(net, skb, laddr, transportp);
1129 /* Lookup an association for an inbound skb. */
1130 static struct sctp_association *__sctp_rcv_lookup(struct net *net,
1131 struct sk_buff *skb,
1132 const union sctp_addr *paddr,
1133 const union sctp_addr *laddr,
1134 struct sctp_transport **transportp)
1136 struct sctp_association *asoc;
1138 asoc = __sctp_lookup_association(net, laddr, paddr, transportp);
1140 /* Further lookup for INIT/INIT-ACK packets.
1141 * SCTP Implementors Guide, 2.18 Handling of address
1142 * parameters within the INIT or INIT-ACK.
1145 asoc = __sctp_rcv_lookup_harder(net, skb, laddr, transportp);