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, write to
27 * the Free Software Foundation, 59 Temple Place - Suite 330,
28 * Boston, MA 02111-1307, USA.
30 * Please send any bug reports or fixes you make to the
32 * lksctp developers <lksctp-developers@lists.sourceforge.net>
34 * Or submit a bug report through the following website:
35 * http://www.sf.net/projects/lksctp
37 * Written or modified by:
38 * La Monte H.P. Yarroll <piggy@acm.org>
39 * Karl Knutson <karl@athena.chicago.il.us>
40 * Xingang Guo <xingang.guo@intel.com>
41 * Jon Grimm <jgrimm@us.ibm.com>
42 * Hui Huang <hui.huang@nokia.com>
43 * Daisy Chang <daisyc@us.ibm.com>
44 * Sridhar Samudrala <sri@us.ibm.com>
45 * Ardelle Fan <ardelle.fan@intel.com>
47 * Any bugs reported given to us we will try to fix... any fixes shared will
48 * be incorporated into the next SCTP release.
51 #include <linux/types.h>
52 #include <linux/list.h> /* For struct list_head */
53 #include <linux/socket.h>
55 #include <linux/time.h> /* For struct timeval */
61 #include <net/sctp/sctp.h>
62 #include <net/sctp/sm.h>
63 #include <net/sctp/checksum.h>
64 #include <net/net_namespace.h>
66 /* Forward declarations for internal helpers. */
67 static int sctp_rcv_ootb(struct sk_buff *);
68 static struct sctp_association *__sctp_rcv_lookup(struct sk_buff *skb,
69 const union sctp_addr *laddr,
70 const union sctp_addr *paddr,
71 struct sctp_transport **transportp);
72 static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr);
73 static struct sctp_association *__sctp_lookup_association(
74 const union sctp_addr *local,
75 const union sctp_addr *peer,
76 struct sctp_transport **pt);
78 static void sctp_add_backlog(struct sock *sk, struct sk_buff *skb);
81 /* Calculate the SCTP checksum of an SCTP packet. */
82 static inline int sctp_rcv_checksum(struct sk_buff *skb)
84 struct sk_buff *list = skb_shinfo(skb)->frag_list;
85 struct sctphdr *sh = sctp_hdr(skb);
86 __le32 cmp = sh->checksum;
88 __u32 tmp = sctp_start_cksum((__u8 *)sh, skb_headlen(skb));
90 for (; list; list = list->next)
91 tmp = sctp_update_cksum((__u8 *)list->data, skb_headlen(list),
94 val = sctp_end_cksum(tmp);
97 /* CRC failure, dump it. */
98 SCTP_INC_STATS_BH(SCTP_MIB_CHECKSUMERRORS);
104 struct sctp_input_cb {
106 struct inet_skb_parm h4;
107 #if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
108 struct inet6_skb_parm h6;
111 struct sctp_chunk *chunk;
113 #define SCTP_INPUT_CB(__skb) ((struct sctp_input_cb *)&((__skb)->cb[0]))
116 * This is the routine which IP calls when receiving an SCTP packet.
118 int sctp_rcv(struct sk_buff *skb)
121 struct sctp_association *asoc;
122 struct sctp_endpoint *ep = NULL;
123 struct sctp_ep_common *rcvr;
124 struct sctp_transport *transport = NULL;
125 struct sctp_chunk *chunk;
128 union sctp_addr dest;
132 if (skb->pkt_type!=PACKET_HOST)
135 SCTP_INC_STATS_BH(SCTP_MIB_INSCTPPACKS);
137 if (skb_linearize(skb))
142 /* Pull up the IP and SCTP headers. */
143 __skb_pull(skb, skb_transport_offset(skb));
144 if (skb->len < sizeof(struct sctphdr))
146 if (!sctp_checksum_disable && !skb_csum_unnecessary(skb) &&
147 sctp_rcv_checksum(skb) < 0)
150 skb_pull(skb, sizeof(struct sctphdr));
152 /* Make sure we at least have chunk headers worth of data left. */
153 if (skb->len < sizeof(struct sctp_chunkhdr))
156 family = ipver2af(ip_hdr(skb)->version);
157 af = sctp_get_af_specific(family);
161 /* Initialize local addresses for lookups. */
162 af->from_skb(&src, skb, 1);
163 af->from_skb(&dest, skb, 0);
165 /* If the packet is to or from a non-unicast address,
166 * silently discard the packet.
168 * This is not clearly defined in the RFC except in section
169 * 8.4 - OOTB handling. However, based on the book "Stream Control
170 * Transmission Protocol" 2.1, "It is important to note that the
171 * IP address of an SCTP transport address must be a routable
172 * unicast address. In other words, IP multicast addresses and
173 * IP broadcast addresses cannot be used in an SCTP transport
176 if (!af->addr_valid(&src, NULL, skb) ||
177 !af->addr_valid(&dest, NULL, skb))
180 asoc = __sctp_rcv_lookup(skb, &src, &dest, &transport);
183 ep = __sctp_rcv_lookup_endpoint(&dest);
185 /* Retrieve the common input handling substructure. */
186 rcvr = asoc ? &asoc->base : &ep->base;
190 * If a frame arrives on an interface and the receiving socket is
191 * bound to another interface, via SO_BINDTODEVICE, treat it as OOTB
193 if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb)))
196 sctp_association_put(asoc);
199 sctp_endpoint_put(ep);
202 sk = sctp_get_ctl_sock();
203 ep = sctp_sk(sk)->ep;
204 sctp_endpoint_hold(ep);
209 * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
210 * An SCTP packet is called an "out of the blue" (OOTB)
211 * packet if it is correctly formed, i.e., passed the
212 * receiver's checksum check, but the receiver is not
213 * able to identify the association to which this
217 if (sctp_rcv_ootb(skb)) {
218 SCTP_INC_STATS_BH(SCTP_MIB_OUTOFBLUES);
219 goto discard_release;
223 if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family))
224 goto discard_release;
227 if (sk_filter(sk, skb))
228 goto discard_release;
230 /* Create an SCTP packet structure. */
231 chunk = sctp_chunkify(skb, asoc, sk);
233 goto discard_release;
234 SCTP_INPUT_CB(skb)->chunk = chunk;
236 /* Remember what endpoint is to handle this packet. */
239 /* Remember the SCTP header. */
240 chunk->sctp_hdr = sh;
242 /* Set the source and destination addresses of the incoming chunk. */
243 sctp_init_addrs(chunk, &src, &dest);
245 /* Remember where we came from. */
246 chunk->transport = transport;
248 /* Acquire access to the sock lock. Note: We are safe from other
249 * bottom halves on this lock, but a user may be in the lock too,
250 * so check if it is busy.
252 sctp_bh_lock_sock(sk);
254 if (sk != rcvr->sk) {
255 /* Our cached sk is different from the rcvr->sk. This is
256 * because migrate()/accept() may have moved the association
257 * to a new socket and released all the sockets. So now we
258 * are holding a lock on the old socket while the user may
259 * be doing something with the new socket. Switch our veiw
262 sctp_bh_unlock_sock(sk);
264 sctp_bh_lock_sock(sk);
267 if (sock_owned_by_user(sk)) {
268 SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_BACKLOG);
269 sctp_add_backlog(sk, skb);
271 SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_SOFTIRQ);
272 sctp_inq_push(&chunk->rcvr->inqueue, chunk);
275 sctp_bh_unlock_sock(sk);
277 /* Release the asoc/ep ref we took in the lookup calls. */
279 sctp_association_put(asoc);
281 sctp_endpoint_put(ep);
286 SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_DISCARDS);
291 /* Release the asoc/ep ref we took in the lookup calls. */
293 sctp_association_put(asoc);
295 sctp_endpoint_put(ep);
300 /* Process the backlog queue of the socket. Every skb on
301 * the backlog holds a ref on an association or endpoint.
302 * We hold this ref throughout the state machine to make
303 * sure that the structure we need is still around.
305 int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
307 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
308 struct sctp_inq *inqueue = &chunk->rcvr->inqueue;
309 struct sctp_ep_common *rcvr = NULL;
314 /* If the rcvr is dead then the association or endpoint
315 * has been deleted and we can safely drop the chunk
316 * and refs that we are holding.
319 sctp_chunk_free(chunk);
323 if (unlikely(rcvr->sk != sk)) {
324 /* In this case, the association moved from one socket to
325 * another. We are currently sitting on the backlog of the
326 * old socket, so we need to move.
327 * However, since we are here in the process context we
328 * need to take make sure that the user doesn't own
329 * the new socket when we process the packet.
330 * If the new socket is user-owned, queue the chunk to the
331 * backlog of the new socket without dropping any refs.
332 * Otherwise, we can safely push the chunk on the inqueue.
336 sctp_bh_lock_sock(sk);
338 if (sock_owned_by_user(sk)) {
339 sk_add_backlog(sk, skb);
342 sctp_inq_push(inqueue, chunk);
344 sctp_bh_unlock_sock(sk);
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 void 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;
370 /* Hold the assoc/ep while hanging on the backlog queue.
371 * This way, we know structures we need will not disappear from us
373 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
374 sctp_association_hold(sctp_assoc(rcvr));
375 else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
376 sctp_endpoint_hold(sctp_ep(rcvr));
380 sk_add_backlog(sk, skb);
383 /* Handle icmp frag needed error. */
384 void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc,
385 struct sctp_transport *t, __u32 pmtu)
387 if (!t || (t->pathmtu <= pmtu))
390 if (sock_owned_by_user(sk)) {
391 asoc->pmtu_pending = 1;
396 if (t->param_flags & SPP_PMTUD_ENABLE) {
397 /* Update transports view of the MTU */
398 sctp_transport_update_pmtu(t, pmtu);
400 /* Update association pmtu. */
401 sctp_assoc_sync_pmtu(asoc);
404 /* Retransmit with the new pmtu setting.
405 * Normally, if PMTU discovery is disabled, an ICMP Fragmentation
406 * Needed will never be sent, but if a message was sent before
407 * PMTU discovery was disabled that was larger than the PMTU, it
408 * would not be fragmented, so it must be re-transmitted fragmented.
410 sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD);
414 * SCTP Implementer's Guide, 2.37 ICMP handling procedures
416 * ICMP8) If the ICMP code is a "Unrecognized next header type encountered"
417 * or a "Protocol Unreachable" treat this message as an abort
418 * with the T bit set.
420 * This function sends an event to the state machine, which will abort the
424 void sctp_icmp_proto_unreachable(struct sock *sk,
425 struct sctp_association *asoc,
426 struct sctp_transport *t)
428 SCTP_DEBUG_PRINTK("%s\n", __func__);
430 sctp_do_sm(SCTP_EVENT_T_OTHER,
431 SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH),
432 asoc->state, asoc->ep, asoc, t,
437 /* Common lookup code for icmp/icmpv6 error handler. */
438 struct sock *sctp_err_lookup(int family, struct sk_buff *skb,
439 struct sctphdr *sctphdr,
440 struct sctp_association **app,
441 struct sctp_transport **tpp)
443 union sctp_addr saddr;
444 union sctp_addr daddr;
446 struct sock *sk = NULL;
447 struct sctp_association *asoc;
448 struct sctp_transport *transport = NULL;
449 struct sctp_init_chunk *chunkhdr;
450 __u32 vtag = ntohl(sctphdr->vtag);
451 int len = skb->len - ((void *)sctphdr - (void *)skb->data);
453 *app = NULL; *tpp = NULL;
455 af = sctp_get_af_specific(family);
460 /* Initialize local addresses for lookups. */
461 af->from_skb(&saddr, skb, 1);
462 af->from_skb(&daddr, skb, 0);
464 /* Look for an association that matches the incoming ICMP error
467 asoc = __sctp_lookup_association(&saddr, &daddr, &transport);
473 /* RFC 4960, Appendix C. ICMP Handling
475 * ICMP6) An implementation MUST validate that the Verification Tag
476 * contained in the ICMP message matches the Verification Tag of
477 * the peer. If the Verification Tag is not 0 and does NOT
478 * match, discard the ICMP message. If it is 0 and the ICMP
479 * message contains enough bytes to verify that the chunk type is
480 * an INIT chunk and that the Initiate Tag matches the tag of the
481 * peer, continue with ICMP7. If the ICMP message is too short
482 * or the chunk type or the Initiate Tag does not match, silently
483 * discard the packet.
486 chunkhdr = (struct sctp_init_chunk *)((void *)sctphdr
487 + sizeof(struct sctphdr));
488 if (len < sizeof(struct sctphdr) + sizeof(sctp_chunkhdr_t)
490 chunkhdr->chunk_hdr.type != SCTP_CID_INIT ||
491 ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag) {
494 } else if (vtag != asoc->c.peer_vtag) {
498 sctp_bh_lock_sock(sk);
500 /* If too many ICMPs get dropped on busy
501 * servers this needs to be solved differently.
503 if (sock_owned_by_user(sk))
504 NET_INC_STATS_BH(&init_net, LINUX_MIB_LOCKDROPPEDICMPS);
512 sctp_association_put(asoc);
516 /* Common cleanup code for icmp/icmpv6 error handler. */
517 void sctp_err_finish(struct sock *sk, struct sctp_association *asoc)
519 sctp_bh_unlock_sock(sk);
521 sctp_association_put(asoc);
525 * This routine is called by the ICMP module when it gets some
526 * sort of error condition. If err < 0 then the socket should
527 * be closed and the error returned to the user. If err > 0
528 * it's just the icmp type << 8 | icmp code. After adjustment
529 * header points to the first 8 bytes of the sctp header. We need
530 * to find the appropriate port.
532 * The locking strategy used here is very "optimistic". When
533 * someone else accesses the socket the ICMP is just dropped
534 * and for some paths there is no check at all.
535 * A more general error queue to queue errors for later handling
536 * is probably better.
539 void sctp_v4_err(struct sk_buff *skb, __u32 info)
541 struct iphdr *iph = (struct iphdr *)skb->data;
542 const int ihlen = iph->ihl * 4;
543 const int type = icmp_hdr(skb)->type;
544 const int code = icmp_hdr(skb)->code;
546 struct sctp_association *asoc = NULL;
547 struct sctp_transport *transport;
548 struct inet_sock *inet;
549 sk_buff_data_t saveip, savesctp;
552 if (skb->len < ihlen + 8) {
553 ICMP_INC_STATS_BH(&init_net, ICMP_MIB_INERRORS);
557 /* Fix up skb to look at the embedded net header. */
558 saveip = skb->network_header;
559 savesctp = skb->transport_header;
560 skb_reset_network_header(skb);
561 skb_set_transport_header(skb, ihlen);
562 sk = sctp_err_lookup(AF_INET, skb, sctp_hdr(skb), &asoc, &transport);
563 /* Put back, the original values. */
564 skb->network_header = saveip;
565 skb->transport_header = savesctp;
567 ICMP_INC_STATS_BH(&init_net, ICMP_MIB_INERRORS);
570 /* Warning: The sock lock is held. Remember to call
575 case ICMP_PARAMETERPROB:
578 case ICMP_DEST_UNREACH:
579 if (code > NR_ICMP_UNREACH)
582 /* PMTU discovery (RFC1191) */
583 if (ICMP_FRAG_NEEDED == code) {
584 sctp_icmp_frag_needed(sk, asoc, transport, info);
588 if (ICMP_PROT_UNREACH == code) {
589 sctp_icmp_proto_unreachable(sk, asoc,
594 err = icmp_err_convert[code].errno;
596 case ICMP_TIME_EXCEEDED:
597 /* Ignore any time exceeded errors due to fragment reassembly
600 if (ICMP_EXC_FRAGTIME == code)
610 if (!sock_owned_by_user(sk) && inet->recverr) {
612 sk->sk_error_report(sk);
613 } else { /* Only an error on timeout */
614 sk->sk_err_soft = err;
618 sctp_err_finish(sk, asoc);
622 * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
624 * This function scans all the chunks in the OOTB packet to determine if
625 * the packet should be discarded right away. If a response might be needed
626 * for this packet, or, if further processing is possible, the packet will
627 * be queued to a proper inqueue for the next phase of handling.
630 * Return 0 - If further processing is needed.
631 * Return 1 - If the packet can be discarded right away.
633 static int sctp_rcv_ootb(struct sk_buff *skb)
639 ch = (sctp_chunkhdr_t *) skb->data;
641 /* Scan through all the chunks in the packet. */
643 /* Break out if chunk length is less then minimal. */
644 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
647 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
648 if (ch_end > skb_tail_pointer(skb))
651 /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the
652 * receiver MUST silently discard the OOTB packet and take no
655 if (SCTP_CID_ABORT == ch->type)
658 /* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE
659 * chunk, the receiver should silently discard the packet
660 * and take no further action.
662 if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type)
666 * This will discard packets with INIT chunk bundled as
667 * subsequent chunks in the packet. When INIT is first,
668 * the normal INIT processing will discard the chunk.
670 if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data)
673 /* RFC 8.4, 7) If the packet contains a "Stale cookie" ERROR
674 * or a COOKIE ACK the SCTP Packet should be silently
677 if (SCTP_CID_COOKIE_ACK == ch->type)
680 if (SCTP_CID_ERROR == ch->type) {
681 sctp_walk_errors(err, ch) {
682 if (SCTP_ERROR_STALE_COOKIE == err->cause)
687 ch = (sctp_chunkhdr_t *) ch_end;
688 } while (ch_end < skb_tail_pointer(skb));
696 /* Insert endpoint into the hash table. */
697 static void __sctp_hash_endpoint(struct sctp_endpoint *ep)
699 struct sctp_ep_common *epb;
700 struct sctp_hashbucket *head;
704 epb->hashent = sctp_ep_hashfn(epb->bind_addr.port);
705 head = &sctp_ep_hashtable[epb->hashent];
707 sctp_write_lock(&head->lock);
708 hlist_add_head(&epb->node, &head->chain);
709 sctp_write_unlock(&head->lock);
712 /* Add an endpoint to the hash. Local BH-safe. */
713 void sctp_hash_endpoint(struct sctp_endpoint *ep)
715 sctp_local_bh_disable();
716 __sctp_hash_endpoint(ep);
717 sctp_local_bh_enable();
720 /* Remove endpoint from the hash table. */
721 static void __sctp_unhash_endpoint(struct sctp_endpoint *ep)
723 struct sctp_hashbucket *head;
724 struct sctp_ep_common *epb;
728 if (hlist_unhashed(&epb->node))
731 epb->hashent = sctp_ep_hashfn(epb->bind_addr.port);
733 head = &sctp_ep_hashtable[epb->hashent];
735 sctp_write_lock(&head->lock);
736 __hlist_del(&epb->node);
737 sctp_write_unlock(&head->lock);
740 /* Remove endpoint from the hash. Local BH-safe. */
741 void sctp_unhash_endpoint(struct sctp_endpoint *ep)
743 sctp_local_bh_disable();
744 __sctp_unhash_endpoint(ep);
745 sctp_local_bh_enable();
748 /* Look up an endpoint. */
749 static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr)
751 struct sctp_hashbucket *head;
752 struct sctp_ep_common *epb;
753 struct sctp_endpoint *ep;
754 struct hlist_node *node;
757 hash = sctp_ep_hashfn(ntohs(laddr->v4.sin_port));
758 head = &sctp_ep_hashtable[hash];
759 read_lock(&head->lock);
760 sctp_for_each_hentry(epb, node, &head->chain) {
762 if (sctp_endpoint_is_match(ep, laddr))
766 ep = sctp_sk((sctp_get_ctl_sock()))->ep;
769 sctp_endpoint_hold(ep);
770 read_unlock(&head->lock);
774 /* Insert association into the hash table. */
775 static void __sctp_hash_established(struct sctp_association *asoc)
777 struct sctp_ep_common *epb;
778 struct sctp_hashbucket *head;
782 /* Calculate which chain this entry will belong to. */
783 epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port, asoc->peer.port);
785 head = &sctp_assoc_hashtable[epb->hashent];
787 sctp_write_lock(&head->lock);
788 hlist_add_head(&epb->node, &head->chain);
789 sctp_write_unlock(&head->lock);
792 /* Add an association to the hash. Local BH-safe. */
793 void sctp_hash_established(struct sctp_association *asoc)
798 sctp_local_bh_disable();
799 __sctp_hash_established(asoc);
800 sctp_local_bh_enable();
803 /* Remove association from the hash table. */
804 static void __sctp_unhash_established(struct sctp_association *asoc)
806 struct sctp_hashbucket *head;
807 struct sctp_ep_common *epb;
811 epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port,
814 head = &sctp_assoc_hashtable[epb->hashent];
816 sctp_write_lock(&head->lock);
817 __hlist_del(&epb->node);
818 sctp_write_unlock(&head->lock);
821 /* Remove association from the hash table. Local BH-safe. */
822 void sctp_unhash_established(struct sctp_association *asoc)
827 sctp_local_bh_disable();
828 __sctp_unhash_established(asoc);
829 sctp_local_bh_enable();
832 /* Look up an association. */
833 static struct sctp_association *__sctp_lookup_association(
834 const union sctp_addr *local,
835 const union sctp_addr *peer,
836 struct sctp_transport **pt)
838 struct sctp_hashbucket *head;
839 struct sctp_ep_common *epb;
840 struct sctp_association *asoc;
841 struct sctp_transport *transport;
842 struct hlist_node *node;
845 /* Optimize here for direct hit, only listening connections can
846 * have wildcards anyways.
848 hash = sctp_assoc_hashfn(ntohs(local->v4.sin_port), ntohs(peer->v4.sin_port));
849 head = &sctp_assoc_hashtable[hash];
850 read_lock(&head->lock);
851 sctp_for_each_hentry(epb, node, &head->chain) {
852 asoc = sctp_assoc(epb);
853 transport = sctp_assoc_is_match(asoc, local, peer);
858 read_unlock(&head->lock);
864 sctp_association_hold(asoc);
865 read_unlock(&head->lock);
869 /* Look up an association. BH-safe. */
871 struct sctp_association *sctp_lookup_association(const union sctp_addr *laddr,
872 const union sctp_addr *paddr,
873 struct sctp_transport **transportp)
875 struct sctp_association *asoc;
877 sctp_local_bh_disable();
878 asoc = __sctp_lookup_association(laddr, paddr, transportp);
879 sctp_local_bh_enable();
884 /* Is there an association matching the given local and peer addresses? */
885 int sctp_has_association(const union sctp_addr *laddr,
886 const union sctp_addr *paddr)
888 struct sctp_association *asoc;
889 struct sctp_transport *transport;
891 if ((asoc = sctp_lookup_association(laddr, paddr, &transport))) {
892 sctp_association_put(asoc);
900 * SCTP Implementors Guide, 2.18 Handling of address
901 * parameters within the INIT or INIT-ACK.
903 * D) When searching for a matching TCB upon reception of an INIT
904 * or INIT-ACK chunk the receiver SHOULD use not only the
905 * source address of the packet (containing the INIT or
906 * INIT-ACK) but the receiver SHOULD also use all valid
907 * address parameters contained within the chunk.
909 * 2.18.3 Solution description
911 * This new text clearly specifies to an implementor the need
912 * to look within the INIT or INIT-ACK. Any implementation that
913 * does not do this, may not be able to establish associations
914 * in certain circumstances.
917 static struct sctp_association *__sctp_rcv_init_lookup(struct sk_buff *skb,
918 const union sctp_addr *laddr, struct sctp_transport **transportp)
920 struct sctp_association *asoc;
921 union sctp_addr addr;
922 union sctp_addr *paddr = &addr;
923 struct sctphdr *sh = sctp_hdr(skb);
925 union sctp_params params;
926 sctp_init_chunk_t *init;
927 struct sctp_transport *transport;
930 ch = (sctp_chunkhdr_t *) skb->data;
933 * This code will NOT touch anything inside the chunk--it is
934 * strictly READ-ONLY.
936 * RFC 2960 3 SCTP packet Format
938 * Multiple chunks can be bundled into one SCTP packet up to
939 * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN
940 * COMPLETE chunks. These chunks MUST NOT be bundled with any
941 * other chunk in a packet. See Section 6.10 for more details
945 /* Find the start of the TLVs and the end of the chunk. This is
946 * the region we search for address parameters.
948 init = (sctp_init_chunk_t *)skb->data;
950 /* Walk the parameters looking for embedded addresses. */
951 sctp_walk_params(params, init, init_hdr.params) {
953 /* Note: Ignoring hostname addresses. */
954 af = sctp_get_af_specific(param_type2af(params.p->type));
958 af->from_addr_param(paddr, params.addr, sh->source, 0);
960 asoc = __sctp_lookup_association(laddr, paddr, &transport);
968 /* ADD-IP, Section 5.2
969 * When an endpoint receives an ASCONF Chunk from the remote peer
970 * special procedures may be needed to identify the association the
971 * ASCONF Chunk is associated with. To properly find the association
972 * the following procedures SHOULD be followed:
974 * D2) If the association is not found, use the address found in the
975 * Address Parameter TLV combined with the port number found in the
976 * SCTP common header. If found proceed to rule D4.
978 * D2-ext) If more than one ASCONF Chunks are packed together, use the
979 * address found in the ASCONF Address Parameter TLV of each of the
980 * subsequent ASCONF Chunks. If found, proceed to rule D4.
982 static struct sctp_association *__sctp_rcv_asconf_lookup(
984 const union sctp_addr *laddr,
986 struct sctp_transport **transportp)
988 sctp_addip_chunk_t *asconf = (struct sctp_addip_chunk *)ch;
990 union sctp_addr_param *param;
991 union sctp_addr paddr;
993 /* Skip over the ADDIP header and find the Address parameter */
994 param = (union sctp_addr_param *)(asconf + 1);
996 af = sctp_get_af_specific(param_type2af(param->v4.param_hdr.type));
1000 af->from_addr_param(&paddr, param, peer_port, 0);
1002 return __sctp_lookup_association(laddr, &paddr, transportp);
1006 /* SCTP-AUTH, Section 6.3:
1007 * If the receiver does not find a STCB for a packet containing an AUTH
1008 * chunk as the first chunk and not a COOKIE-ECHO chunk as the second
1009 * chunk, it MUST use the chunks after the AUTH chunk to look up an existing
1012 * This means that any chunks that can help us identify the association need
1013 * to be looked at to find this assocation.
1015 static struct sctp_association *__sctp_rcv_walk_lookup(struct sk_buff *skb,
1016 const union sctp_addr *laddr,
1017 struct sctp_transport **transportp)
1019 struct sctp_association *asoc = NULL;
1020 sctp_chunkhdr_t *ch;
1022 unsigned int chunk_num = 1;
1025 /* Walk through the chunks looking for AUTH or ASCONF chunks
1026 * to help us find the association.
1028 ch = (sctp_chunkhdr_t *) skb->data;
1030 /* Break out if chunk length is less then minimal. */
1031 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
1034 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
1035 if (ch_end > skb_tail_pointer(skb))
1040 have_auth = chunk_num;
1043 case SCTP_CID_COOKIE_ECHO:
1044 /* If a packet arrives containing an AUTH chunk as
1045 * a first chunk, a COOKIE-ECHO chunk as the second
1046 * chunk, and possibly more chunks after them, and
1047 * the receiver does not have an STCB for that
1048 * packet, then authentication is based on
1049 * the contents of the COOKIE- ECHO chunk.
1051 if (have_auth == 1 && chunk_num == 2)
1055 case SCTP_CID_ASCONF:
1056 if (have_auth || sctp_addip_noauth)
1057 asoc = __sctp_rcv_asconf_lookup(ch, laddr,
1058 sctp_hdr(skb)->source,
1067 ch = (sctp_chunkhdr_t *) ch_end;
1069 } while (ch_end < skb_tail_pointer(skb));
1075 * There are circumstances when we need to look inside the SCTP packet
1076 * for information to help us find the association. Examples
1077 * include looking inside of INIT/INIT-ACK chunks or after the AUTH
1080 static struct sctp_association *__sctp_rcv_lookup_harder(struct sk_buff *skb,
1081 const union sctp_addr *laddr,
1082 struct sctp_transport **transportp)
1084 sctp_chunkhdr_t *ch;
1086 ch = (sctp_chunkhdr_t *) skb->data;
1088 /* The code below will attempt to walk the chunk and extract
1089 * parameter information. Before we do that, we need to verify
1090 * that the chunk length doesn't cause overflow. Otherwise, we'll
1093 if (WORD_ROUND(ntohs(ch->length)) > skb->len)
1096 /* If this is INIT/INIT-ACK look inside the chunk too. */
1099 case SCTP_CID_INIT_ACK:
1100 return __sctp_rcv_init_lookup(skb, laddr, transportp);
1104 return __sctp_rcv_walk_lookup(skb, laddr, transportp);
1112 /* Lookup an association for an inbound skb. */
1113 static struct sctp_association *__sctp_rcv_lookup(struct sk_buff *skb,
1114 const union sctp_addr *paddr,
1115 const union sctp_addr *laddr,
1116 struct sctp_transport **transportp)
1118 struct sctp_association *asoc;
1120 asoc = __sctp_lookup_association(laddr, paddr, transportp);
1122 /* Further lookup for INIT/INIT-ACK packets.
1123 * SCTP Implementors Guide, 2.18 Handling of address
1124 * parameters within the INIT or INIT-ACK.
1127 asoc = __sctp_rcv_lookup_harder(skb, laddr, transportp);