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))
136 if (!sctp_checksum_disable && !skb_csum_unnecessary(skb) &&
137 sctp_rcv_checksum(net, skb) < 0)
140 skb_pull(skb, sizeof(struct sctphdr));
142 /* Make sure we at least have chunk headers worth of data left. */
143 if (skb->len < sizeof(struct sctp_chunkhdr))
146 family = ipver2af(ip_hdr(skb)->version);
147 af = sctp_get_af_specific(family);
151 /* Initialize local addresses for lookups. */
152 af->from_skb(&src, skb, 1);
153 af->from_skb(&dest, skb, 0);
155 /* If the packet is to or from a non-unicast address,
156 * silently discard the packet.
158 * This is not clearly defined in the RFC except in section
159 * 8.4 - OOTB handling. However, based on the book "Stream Control
160 * Transmission Protocol" 2.1, "It is important to note that the
161 * IP address of an SCTP transport address must be a routable
162 * unicast address. In other words, IP multicast addresses and
163 * IP broadcast addresses cannot be used in an SCTP transport
166 if (!af->addr_valid(&src, NULL, skb) ||
167 !af->addr_valid(&dest, NULL, skb))
170 asoc = __sctp_rcv_lookup(net, skb, &src, &dest, &transport);
173 ep = __sctp_rcv_lookup_endpoint(net, &dest);
175 /* Retrieve the common input handling substructure. */
176 rcvr = asoc ? &asoc->base : &ep->base;
180 * If a frame arrives on an interface and the receiving socket is
181 * bound to another interface, via SO_BINDTODEVICE, treat it as OOTB
183 if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb)))
186 sctp_association_put(asoc);
189 sctp_endpoint_put(ep);
192 sk = net->sctp.ctl_sock;
193 ep = sctp_sk(sk)->ep;
194 sctp_endpoint_hold(ep);
199 * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
200 * An SCTP packet is called an "out of the blue" (OOTB)
201 * packet if it is correctly formed, i.e., passed the
202 * receiver's checksum check, but the receiver is not
203 * able to identify the association to which this
207 if (sctp_rcv_ootb(skb)) {
208 SCTP_INC_STATS_BH(net, SCTP_MIB_OUTOFBLUES);
209 goto discard_release;
213 if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family))
214 goto discard_release;
217 if (sk_filter(sk, skb))
218 goto discard_release;
220 /* Create an SCTP packet structure. */
221 chunk = sctp_chunkify(skb, asoc, sk);
223 goto discard_release;
224 SCTP_INPUT_CB(skb)->chunk = chunk;
226 /* Remember what endpoint is to handle this packet. */
229 /* Remember the SCTP header. */
230 chunk->sctp_hdr = sh;
232 /* Set the source and destination addresses of the incoming chunk. */
233 sctp_init_addrs(chunk, &src, &dest);
235 /* Remember where we came from. */
236 chunk->transport = transport;
238 /* Acquire access to the sock lock. Note: We are safe from other
239 * bottom halves on this lock, but a user may be in the lock too,
240 * so check if it is busy.
242 sctp_bh_lock_sock(sk);
244 if (sk != rcvr->sk) {
245 /* Our cached sk is different from the rcvr->sk. This is
246 * because migrate()/accept() may have moved the association
247 * to a new socket and released all the sockets. So now we
248 * are holding a lock on the old socket while the user may
249 * be doing something with the new socket. Switch our veiw
252 sctp_bh_unlock_sock(sk);
254 sctp_bh_lock_sock(sk);
257 if (sock_owned_by_user(sk)) {
258 if (sctp_add_backlog(sk, skb)) {
259 sctp_bh_unlock_sock(sk);
260 sctp_chunk_free(chunk);
261 skb = NULL; /* sctp_chunk_free already freed the skb */
262 goto discard_release;
264 SCTP_INC_STATS_BH(net, SCTP_MIB_IN_PKT_BACKLOG);
266 SCTP_INC_STATS_BH(net, SCTP_MIB_IN_PKT_SOFTIRQ);
267 sctp_inq_push(&chunk->rcvr->inqueue, chunk);
270 sctp_bh_unlock_sock(sk);
272 /* Release the asoc/ep ref we took in the lookup calls. */
274 sctp_association_put(asoc);
276 sctp_endpoint_put(ep);
281 SCTP_INC_STATS_BH(net, SCTP_MIB_IN_PKT_DISCARDS);
286 /* Release the asoc/ep ref we took in the lookup calls. */
288 sctp_association_put(asoc);
290 sctp_endpoint_put(ep);
295 /* Process the backlog queue of the socket. Every skb on
296 * the backlog holds a ref on an association or endpoint.
297 * We hold this ref throughout the state machine to make
298 * sure that the structure we need is still around.
300 int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
302 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
303 struct sctp_inq *inqueue = &chunk->rcvr->inqueue;
304 struct sctp_ep_common *rcvr = NULL;
309 /* If the rcvr is dead then the association or endpoint
310 * has been deleted and we can safely drop the chunk
311 * and refs that we are holding.
314 sctp_chunk_free(chunk);
318 if (unlikely(rcvr->sk != sk)) {
319 /* In this case, the association moved from one socket to
320 * another. We are currently sitting on the backlog of the
321 * old socket, so we need to move.
322 * However, since we are here in the process context we
323 * need to take make sure that the user doesn't own
324 * the new socket when we process the packet.
325 * If the new socket is user-owned, queue the chunk to the
326 * backlog of the new socket without dropping any refs.
327 * Otherwise, we can safely push the chunk on the inqueue.
331 sctp_bh_lock_sock(sk);
333 if (sock_owned_by_user(sk)) {
334 if (sk_add_backlog(sk, skb, sk->sk_rcvbuf))
335 sctp_chunk_free(chunk);
339 sctp_inq_push(inqueue, chunk);
341 sctp_bh_unlock_sock(sk);
343 /* If the chunk was backloged again, don't drop refs */
347 sctp_inq_push(inqueue, chunk);
351 /* Release the refs we took in sctp_add_backlog */
352 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
353 sctp_association_put(sctp_assoc(rcvr));
354 else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
355 sctp_endpoint_put(sctp_ep(rcvr));
362 static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb)
364 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
365 struct sctp_ep_common *rcvr = chunk->rcvr;
368 ret = sk_add_backlog(sk, skb, sk->sk_rcvbuf);
370 /* Hold the assoc/ep while hanging on the backlog queue.
371 * This way, we know structures we need will not disappear
374 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
375 sctp_association_hold(sctp_assoc(rcvr));
376 else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
377 sctp_endpoint_hold(sctp_ep(rcvr));
385 /* Handle icmp frag needed error. */
386 void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc,
387 struct sctp_transport *t, __u32 pmtu)
389 if (!t || (t->pathmtu <= pmtu))
392 if (sock_owned_by_user(sk)) {
393 asoc->pmtu_pending = 1;
398 if (t->param_flags & SPP_PMTUD_ENABLE) {
399 /* Update transports view of the MTU */
400 sctp_transport_update_pmtu(sk, t, pmtu);
402 /* Update association pmtu. */
403 sctp_assoc_sync_pmtu(sk, asoc);
406 /* Retransmit with the new pmtu setting.
407 * Normally, if PMTU discovery is disabled, an ICMP Fragmentation
408 * Needed will never be sent, but if a message was sent before
409 * PMTU discovery was disabled that was larger than the PMTU, it
410 * would not be fragmented, so it must be re-transmitted fragmented.
412 sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD);
415 void sctp_icmp_redirect(struct sock *sk, struct sctp_transport *t,
418 struct dst_entry *dst;
422 dst = sctp_transport_dst_check(t);
424 dst->ops->redirect(dst, sk, skb);
428 * SCTP Implementer's Guide, 2.37 ICMP handling procedures
430 * ICMP8) If the ICMP code is a "Unrecognized next header type encountered"
431 * or a "Protocol Unreachable" treat this message as an abort
432 * with the T bit set.
434 * This function sends an event to the state machine, which will abort the
438 void sctp_icmp_proto_unreachable(struct sock *sk,
439 struct sctp_association *asoc,
440 struct sctp_transport *t)
442 if (sock_owned_by_user(sk)) {
443 if (timer_pending(&t->proto_unreach_timer))
446 if (!mod_timer(&t->proto_unreach_timer,
448 sctp_association_hold(asoc);
451 struct net *net = sock_net(sk);
453 pr_debug("%s: unrecognized next header type "
454 "encountered!\n", __func__);
456 if (del_timer(&t->proto_unreach_timer))
457 sctp_association_put(asoc);
459 sctp_do_sm(net, SCTP_EVENT_T_OTHER,
460 SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH),
461 asoc->state, asoc->ep, asoc, t,
466 /* Common lookup code for icmp/icmpv6 error handler. */
467 struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *skb,
468 struct sctphdr *sctphdr,
469 struct sctp_association **app,
470 struct sctp_transport **tpp)
472 union sctp_addr saddr;
473 union sctp_addr daddr;
475 struct sock *sk = NULL;
476 struct sctp_association *asoc;
477 struct sctp_transport *transport = NULL;
478 struct sctp_init_chunk *chunkhdr;
479 __u32 vtag = ntohl(sctphdr->vtag);
480 int len = skb->len - ((void *)sctphdr - (void *)skb->data);
482 *app = NULL; *tpp = NULL;
484 af = sctp_get_af_specific(family);
489 /* Initialize local addresses for lookups. */
490 af->from_skb(&saddr, skb, 1);
491 af->from_skb(&daddr, skb, 0);
493 /* Look for an association that matches the incoming ICMP error
496 asoc = __sctp_lookup_association(net, &saddr, &daddr, &transport);
502 /* RFC 4960, Appendix C. ICMP Handling
504 * ICMP6) An implementation MUST validate that the Verification Tag
505 * contained in the ICMP message matches the Verification Tag of
506 * the peer. If the Verification Tag is not 0 and does NOT
507 * match, discard the ICMP message. If it is 0 and the ICMP
508 * message contains enough bytes to verify that the chunk type is
509 * an INIT chunk and that the Initiate Tag matches the tag of the
510 * peer, continue with ICMP7. If the ICMP message is too short
511 * or the chunk type or the Initiate Tag does not match, silently
512 * discard the packet.
515 chunkhdr = (void *)sctphdr + sizeof(struct sctphdr);
516 if (len < sizeof(struct sctphdr) + sizeof(sctp_chunkhdr_t)
518 chunkhdr->chunk_hdr.type != SCTP_CID_INIT ||
519 ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag) {
522 } else if (vtag != asoc->c.peer_vtag) {
526 sctp_bh_lock_sock(sk);
528 /* If too many ICMPs get dropped on busy
529 * servers this needs to be solved differently.
531 if (sock_owned_by_user(sk))
532 NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
539 sctp_association_put(asoc);
543 /* Common cleanup code for icmp/icmpv6 error handler. */
544 void sctp_err_finish(struct sock *sk, struct sctp_association *asoc)
546 sctp_bh_unlock_sock(sk);
547 sctp_association_put(asoc);
551 * This routine is called by the ICMP module when it gets some
552 * sort of error condition. If err < 0 then the socket should
553 * be closed and the error returned to the user. If err > 0
554 * it's just the icmp type << 8 | icmp code. After adjustment
555 * header points to the first 8 bytes of the sctp header. We need
556 * to find the appropriate port.
558 * The locking strategy used here is very "optimistic". When
559 * someone else accesses the socket the ICMP is just dropped
560 * and for some paths there is no check at all.
561 * A more general error queue to queue errors for later handling
562 * is probably better.
565 void sctp_v4_err(struct sk_buff *skb, __u32 info)
567 const struct iphdr *iph = (const struct iphdr *)skb->data;
568 const int ihlen = iph->ihl * 4;
569 const int type = icmp_hdr(skb)->type;
570 const int code = icmp_hdr(skb)->code;
572 struct sctp_association *asoc = NULL;
573 struct sctp_transport *transport;
574 struct inet_sock *inet;
575 __u16 saveip, savesctp;
577 struct net *net = dev_net(skb->dev);
579 if (skb->len < ihlen + 8) {
580 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
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);
615 if (ICMP_PROT_UNREACH == code) {
616 sctp_icmp_proto_unreachable(sk, asoc,
621 err = icmp_err_convert[code].errno;
623 case ICMP_TIME_EXCEEDED:
624 /* Ignore any time exceeded errors due to fragment reassembly
627 if (ICMP_EXC_FRAGTIME == code)
633 sctp_icmp_redirect(sk, transport, skb);
634 /* Fall through to out_unlock. */
640 if (!sock_owned_by_user(sk) && inet->recverr) {
642 sk->sk_error_report(sk);
643 } else { /* Only an error on timeout */
644 sk->sk_err_soft = err;
648 sctp_err_finish(sk, asoc);
652 * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
654 * This function scans all the chunks in the OOTB packet to determine if
655 * the packet should be discarded right away. If a response might be needed
656 * for this packet, or, if further processing is possible, the packet will
657 * be queued to a proper inqueue for the next phase of handling.
660 * Return 0 - If further processing is needed.
661 * Return 1 - If the packet can be discarded right away.
663 static int sctp_rcv_ootb(struct sk_buff *skb)
668 ch = (sctp_chunkhdr_t *) skb->data;
670 /* Scan through all the chunks in the packet. */
672 /* Break out if chunk length is less then minimal. */
673 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
676 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
677 if (ch_end > skb_tail_pointer(skb))
680 /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the
681 * receiver MUST silently discard the OOTB packet and take no
684 if (SCTP_CID_ABORT == ch->type)
687 /* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE
688 * chunk, the receiver should silently discard the packet
689 * and take no further action.
691 if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type)
695 * This will discard packets with INIT chunk bundled as
696 * subsequent chunks in the packet. When INIT is first,
697 * the normal INIT processing will discard the chunk.
699 if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data)
702 ch = (sctp_chunkhdr_t *) ch_end;
703 } while (ch_end < skb_tail_pointer(skb));
711 /* Insert endpoint into the hash table. */
712 static void __sctp_hash_endpoint(struct sctp_endpoint *ep)
714 struct net *net = sock_net(ep->base.sk);
715 struct sctp_ep_common *epb;
716 struct sctp_hashbucket *head;
720 epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port);
721 head = &sctp_ep_hashtable[epb->hashent];
723 sctp_write_lock(&head->lock);
724 hlist_add_head(&epb->node, &head->chain);
725 sctp_write_unlock(&head->lock);
728 /* Add an endpoint to the hash. Local BH-safe. */
729 void sctp_hash_endpoint(struct sctp_endpoint *ep)
731 sctp_local_bh_disable();
732 __sctp_hash_endpoint(ep);
733 sctp_local_bh_enable();
736 /* Remove endpoint from the hash table. */
737 static void __sctp_unhash_endpoint(struct sctp_endpoint *ep)
739 struct net *net = sock_net(ep->base.sk);
740 struct sctp_hashbucket *head;
741 struct sctp_ep_common *epb;
745 epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port);
747 head = &sctp_ep_hashtable[epb->hashent];
749 sctp_write_lock(&head->lock);
750 hlist_del_init(&epb->node);
751 sctp_write_unlock(&head->lock);
754 /* Remove endpoint from the hash. Local BH-safe. */
755 void sctp_unhash_endpoint(struct sctp_endpoint *ep)
757 sctp_local_bh_disable();
758 __sctp_unhash_endpoint(ep);
759 sctp_local_bh_enable();
762 /* Look up an endpoint. */
763 static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(struct net *net,
764 const union sctp_addr *laddr)
766 struct sctp_hashbucket *head;
767 struct sctp_ep_common *epb;
768 struct sctp_endpoint *ep;
771 hash = sctp_ep_hashfn(net, ntohs(laddr->v4.sin_port));
772 head = &sctp_ep_hashtable[hash];
773 read_lock(&head->lock);
774 sctp_for_each_hentry(epb, &head->chain) {
776 if (sctp_endpoint_is_match(ep, net, laddr))
780 ep = sctp_sk(net->sctp.ctl_sock)->ep;
783 sctp_endpoint_hold(ep);
784 read_unlock(&head->lock);
788 /* Insert association into the hash table. */
789 static void __sctp_hash_established(struct sctp_association *asoc)
791 struct net *net = sock_net(asoc->base.sk);
792 struct sctp_ep_common *epb;
793 struct sctp_hashbucket *head;
797 /* Calculate which chain this entry will belong to. */
798 epb->hashent = sctp_assoc_hashfn(net, epb->bind_addr.port,
801 head = &sctp_assoc_hashtable[epb->hashent];
803 sctp_write_lock(&head->lock);
804 hlist_add_head(&epb->node, &head->chain);
805 sctp_write_unlock(&head->lock);
808 /* Add an association to the hash. Local BH-safe. */
809 void sctp_hash_established(struct sctp_association *asoc)
814 sctp_local_bh_disable();
815 __sctp_hash_established(asoc);
816 sctp_local_bh_enable();
819 /* Remove association from the hash table. */
820 static void __sctp_unhash_established(struct sctp_association *asoc)
822 struct net *net = sock_net(asoc->base.sk);
823 struct sctp_hashbucket *head;
824 struct sctp_ep_common *epb;
828 epb->hashent = sctp_assoc_hashfn(net, epb->bind_addr.port,
831 head = &sctp_assoc_hashtable[epb->hashent];
833 sctp_write_lock(&head->lock);
834 hlist_del_init(&epb->node);
835 sctp_write_unlock(&head->lock);
838 /* Remove association from the hash table. Local BH-safe. */
839 void sctp_unhash_established(struct sctp_association *asoc)
844 sctp_local_bh_disable();
845 __sctp_unhash_established(asoc);
846 sctp_local_bh_enable();
849 /* Look up an association. */
850 static struct sctp_association *__sctp_lookup_association(
852 const union sctp_addr *local,
853 const union sctp_addr *peer,
854 struct sctp_transport **pt)
856 struct sctp_hashbucket *head;
857 struct sctp_ep_common *epb;
858 struct sctp_association *asoc;
859 struct sctp_transport *transport;
862 /* Optimize here for direct hit, only listening connections can
863 * have wildcards anyways.
865 hash = sctp_assoc_hashfn(net, ntohs(local->v4.sin_port),
866 ntohs(peer->v4.sin_port));
867 head = &sctp_assoc_hashtable[hash];
868 read_lock(&head->lock);
869 sctp_for_each_hentry(epb, &head->chain) {
870 asoc = sctp_assoc(epb);
871 transport = sctp_assoc_is_match(asoc, net, local, peer);
876 read_unlock(&head->lock);
882 sctp_association_hold(asoc);
883 read_unlock(&head->lock);
887 /* Look up an association. BH-safe. */
889 struct sctp_association *sctp_lookup_association(struct net *net,
890 const union sctp_addr *laddr,
891 const union sctp_addr *paddr,
892 struct sctp_transport **transportp)
894 struct sctp_association *asoc;
896 sctp_local_bh_disable();
897 asoc = __sctp_lookup_association(net, laddr, paddr, transportp);
898 sctp_local_bh_enable();
903 /* Is there an association matching the given local and peer addresses? */
904 int sctp_has_association(struct net *net,
905 const union sctp_addr *laddr,
906 const union sctp_addr *paddr)
908 struct sctp_association *asoc;
909 struct sctp_transport *transport;
911 if ((asoc = sctp_lookup_association(net, laddr, paddr, &transport))) {
912 sctp_association_put(asoc);
920 * SCTP Implementors Guide, 2.18 Handling of address
921 * parameters within the INIT or INIT-ACK.
923 * D) When searching for a matching TCB upon reception of an INIT
924 * or INIT-ACK chunk the receiver SHOULD use not only the
925 * source address of the packet (containing the INIT or
926 * INIT-ACK) but the receiver SHOULD also use all valid
927 * address parameters contained within the chunk.
929 * 2.18.3 Solution description
931 * This new text clearly specifies to an implementor the need
932 * to look within the INIT or INIT-ACK. Any implementation that
933 * does not do this, may not be able to establish associations
934 * in certain circumstances.
937 static struct sctp_association *__sctp_rcv_init_lookup(struct net *net,
939 const union sctp_addr *laddr, struct sctp_transport **transportp)
941 struct sctp_association *asoc;
942 union sctp_addr addr;
943 union sctp_addr *paddr = &addr;
944 struct sctphdr *sh = sctp_hdr(skb);
945 union sctp_params params;
946 sctp_init_chunk_t *init;
947 struct sctp_transport *transport;
951 * This code will NOT touch anything inside the chunk--it is
952 * strictly READ-ONLY.
954 * RFC 2960 3 SCTP packet Format
956 * Multiple chunks can be bundled into one SCTP packet up to
957 * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN
958 * COMPLETE chunks. These chunks MUST NOT be bundled with any
959 * other chunk in a packet. See Section 6.10 for more details
963 /* Find the start of the TLVs and the end of the chunk. This is
964 * the region we search for address parameters.
966 init = (sctp_init_chunk_t *)skb->data;
968 /* Walk the parameters looking for embedded addresses. */
969 sctp_walk_params(params, init, init_hdr.params) {
971 /* Note: Ignoring hostname addresses. */
972 af = sctp_get_af_specific(param_type2af(params.p->type));
976 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 /* Skip over the ADDIP header and find the Address parameter */
1013 param = (union sctp_addr_param *)(asconf + 1);
1015 af = sctp_get_af_specific(param_type2af(param->p.type));
1019 af->from_addr_param(&paddr, param, peer_port, 0);
1021 return __sctp_lookup_association(net, laddr, &paddr, transportp);
1025 /* SCTP-AUTH, Section 6.3:
1026 * If the receiver does not find a STCB for a packet containing an AUTH
1027 * chunk as the first chunk and not a COOKIE-ECHO chunk as the second
1028 * chunk, it MUST use the chunks after the AUTH chunk to look up an existing
1031 * This means that any chunks that can help us identify the association need
1032 * to be looked at to find this association.
1034 static struct sctp_association *__sctp_rcv_walk_lookup(struct net *net,
1035 struct sk_buff *skb,
1036 const union sctp_addr *laddr,
1037 struct sctp_transport **transportp)
1039 struct sctp_association *asoc = NULL;
1040 sctp_chunkhdr_t *ch;
1042 unsigned int chunk_num = 1;
1045 /* Walk through the chunks looking for AUTH or ASCONF chunks
1046 * to help us find the association.
1048 ch = (sctp_chunkhdr_t *) skb->data;
1050 /* Break out if chunk length is less then minimal. */
1051 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
1054 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
1055 if (ch_end > skb_tail_pointer(skb))
1060 have_auth = chunk_num;
1063 case SCTP_CID_COOKIE_ECHO:
1064 /* If a packet arrives containing an AUTH chunk as
1065 * a first chunk, a COOKIE-ECHO chunk as the second
1066 * chunk, and possibly more chunks after them, and
1067 * the receiver does not have an STCB for that
1068 * packet, then authentication is based on
1069 * the contents of the COOKIE- ECHO chunk.
1071 if (have_auth == 1 && chunk_num == 2)
1075 case SCTP_CID_ASCONF:
1076 if (have_auth || net->sctp.addip_noauth)
1077 asoc = __sctp_rcv_asconf_lookup(
1079 sctp_hdr(skb)->source,
1088 ch = (sctp_chunkhdr_t *) ch_end;
1090 } while (ch_end < skb_tail_pointer(skb));
1096 * There are circumstances when we need to look inside the SCTP packet
1097 * for information to help us find the association. Examples
1098 * include looking inside of INIT/INIT-ACK chunks or after the AUTH
1101 static struct sctp_association *__sctp_rcv_lookup_harder(struct net *net,
1102 struct sk_buff *skb,
1103 const union sctp_addr *laddr,
1104 struct sctp_transport **transportp)
1106 sctp_chunkhdr_t *ch;
1108 ch = (sctp_chunkhdr_t *) skb->data;
1110 /* The code below will attempt to walk the chunk and extract
1111 * parameter information. Before we do that, we need to verify
1112 * that the chunk length doesn't cause overflow. Otherwise, we'll
1115 if (WORD_ROUND(ntohs(ch->length)) > skb->len)
1118 /* If this is INIT/INIT-ACK look inside the chunk too. */
1119 if (ch->type == SCTP_CID_INIT || ch->type == SCTP_CID_INIT_ACK)
1120 return __sctp_rcv_init_lookup(net, skb, laddr, transportp);
1122 return __sctp_rcv_walk_lookup(net, skb, laddr, transportp);
1125 /* Lookup an association for an inbound skb. */
1126 static struct sctp_association *__sctp_rcv_lookup(struct net *net,
1127 struct sk_buff *skb,
1128 const union sctp_addr *paddr,
1129 const union sctp_addr *laddr,
1130 struct sctp_transport **transportp)
1132 struct sctp_association *asoc;
1134 asoc = __sctp_lookup_association(net, laddr, paddr, transportp);
1136 /* Further lookup for INIT/INIT-ACK packets.
1137 * SCTP Implementors Guide, 2.18 Handling of address
1138 * parameters within the INIT or INIT-ACK.
1141 asoc = __sctp_rcv_lookup_harder(net, skb, laddr, transportp);