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 */
56 #include <linux/slab.h>
62 #include <net/sctp/sctp.h>
63 #include <net/sctp/sm.h>
64 #include <net/sctp/checksum.h>
65 #include <net/net_namespace.h>
67 /* Forward declarations for internal helpers. */
68 static int sctp_rcv_ootb(struct sk_buff *);
69 static struct sctp_association *__sctp_rcv_lookup(struct sk_buff *skb,
70 const union sctp_addr *laddr,
71 const union sctp_addr *paddr,
72 struct sctp_transport **transportp);
73 static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr);
74 static struct sctp_association *__sctp_lookup_association(
75 const union sctp_addr *local,
76 const union sctp_addr *peer,
77 struct sctp_transport **pt);
79 static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb);
82 /* Calculate the SCTP checksum of an SCTP packet. */
83 static inline int sctp_rcv_checksum(struct sk_buff *skb)
85 struct sctphdr *sh = sctp_hdr(skb);
86 __le32 cmp = sh->checksum;
89 __u32 tmp = sctp_start_cksum((__u8 *)sh, skb_headlen(skb));
91 skb_walk_frags(skb, list)
92 tmp = sctp_update_cksum((__u8 *)list->data, skb_headlen(list),
95 val = sctp_end_cksum(tmp);
98 /* CRC failure, dump it. */
99 SCTP_INC_STATS_BH(SCTP_MIB_CHECKSUMERRORS);
105 struct sctp_input_cb {
107 struct inet_skb_parm h4;
108 #if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
109 struct inet6_skb_parm h6;
112 struct sctp_chunk *chunk;
114 #define SCTP_INPUT_CB(__skb) ((struct sctp_input_cb *)&((__skb)->cb[0]))
117 * This is the routine which IP calls when receiving an SCTP packet.
119 int sctp_rcv(struct sk_buff *skb)
122 struct sctp_association *asoc;
123 struct sctp_endpoint *ep = NULL;
124 struct sctp_ep_common *rcvr;
125 struct sctp_transport *transport = NULL;
126 struct sctp_chunk *chunk;
129 union sctp_addr dest;
133 if (skb->pkt_type!=PACKET_HOST)
136 SCTP_INC_STATS_BH(SCTP_MIB_INSCTPPACKS);
138 if (skb_linearize(skb))
143 /* Pull up the IP and SCTP headers. */
144 __skb_pull(skb, skb_transport_offset(skb));
145 if (skb->len < sizeof(struct sctphdr))
147 if (!sctp_checksum_disable && !skb_csum_unnecessary(skb) &&
148 sctp_rcv_checksum(skb) < 0)
151 skb_pull(skb, sizeof(struct sctphdr));
153 /* Make sure we at least have chunk headers worth of data left. */
154 if (skb->len < sizeof(struct sctp_chunkhdr))
157 family = ipver2af(ip_hdr(skb)->version);
158 af = sctp_get_af_specific(family);
162 /* Initialize local addresses for lookups. */
163 af->from_skb(&src, skb, 1);
164 af->from_skb(&dest, skb, 0);
166 /* If the packet is to or from a non-unicast address,
167 * silently discard the packet.
169 * This is not clearly defined in the RFC except in section
170 * 8.4 - OOTB handling. However, based on the book "Stream Control
171 * Transmission Protocol" 2.1, "It is important to note that the
172 * IP address of an SCTP transport address must be a routable
173 * unicast address. In other words, IP multicast addresses and
174 * IP broadcast addresses cannot be used in an SCTP transport
177 if (!af->addr_valid(&src, NULL, skb) ||
178 !af->addr_valid(&dest, NULL, skb))
181 asoc = __sctp_rcv_lookup(skb, &src, &dest, &transport);
184 ep = __sctp_rcv_lookup_endpoint(&dest);
186 /* Retrieve the common input handling substructure. */
187 rcvr = asoc ? &asoc->base : &ep->base;
191 * If a frame arrives on an interface and the receiving socket is
192 * bound to another interface, via SO_BINDTODEVICE, treat it as OOTB
194 if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb)))
197 sctp_association_put(asoc);
200 sctp_endpoint_put(ep);
203 sk = sctp_get_ctl_sock();
204 ep = sctp_sk(sk)->ep;
205 sctp_endpoint_hold(ep);
210 * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
211 * An SCTP packet is called an "out of the blue" (OOTB)
212 * packet if it is correctly formed, i.e., passed the
213 * receiver's checksum check, but the receiver is not
214 * able to identify the association to which this
218 if (sctp_rcv_ootb(skb)) {
219 SCTP_INC_STATS_BH(SCTP_MIB_OUTOFBLUES);
220 goto discard_release;
224 if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family))
225 goto discard_release;
228 if (sk_filter(sk, skb))
229 goto discard_release;
231 /* Create an SCTP packet structure. */
232 chunk = sctp_chunkify(skb, asoc, sk);
234 goto discard_release;
235 SCTP_INPUT_CB(skb)->chunk = chunk;
237 /* Remember what endpoint is to handle this packet. */
240 /* Remember the SCTP header. */
241 chunk->sctp_hdr = sh;
243 /* Set the source and destination addresses of the incoming chunk. */
244 sctp_init_addrs(chunk, &src, &dest);
246 /* Remember where we came from. */
247 chunk->transport = transport;
249 /* Acquire access to the sock lock. Note: We are safe from other
250 * bottom halves on this lock, but a user may be in the lock too,
251 * so check if it is busy.
253 sctp_bh_lock_sock(sk);
255 if (sk != rcvr->sk) {
256 /* Our cached sk is different from the rcvr->sk. This is
257 * because migrate()/accept() may have moved the association
258 * to a new socket and released all the sockets. So now we
259 * are holding a lock on the old socket while the user may
260 * be doing something with the new socket. Switch our veiw
263 sctp_bh_unlock_sock(sk);
265 sctp_bh_lock_sock(sk);
268 if (sock_owned_by_user(sk)) {
269 if (sctp_add_backlog(sk, skb)) {
270 sctp_bh_unlock_sock(sk);
271 sctp_chunk_free(chunk);
272 skb = NULL; /* sctp_chunk_free already freed the skb */
273 goto discard_release;
275 SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_BACKLOG);
277 SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_SOFTIRQ);
278 sctp_inq_push(&chunk->rcvr->inqueue, chunk);
281 sctp_bh_unlock_sock(sk);
283 /* Release the asoc/ep ref we took in the lookup calls. */
285 sctp_association_put(asoc);
287 sctp_endpoint_put(ep);
292 SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_DISCARDS);
297 /* Release the asoc/ep ref we took in the lookup calls. */
299 sctp_association_put(asoc);
301 sctp_endpoint_put(ep);
306 /* Process the backlog queue of the socket. Every skb on
307 * the backlog holds a ref on an association or endpoint.
308 * We hold this ref throughout the state machine to make
309 * sure that the structure we need is still around.
311 int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
313 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
314 struct sctp_inq *inqueue = &chunk->rcvr->inqueue;
315 struct sctp_ep_common *rcvr = NULL;
320 /* If the rcvr is dead then the association or endpoint
321 * has been deleted and we can safely drop the chunk
322 * and refs that we are holding.
325 sctp_chunk_free(chunk);
329 if (unlikely(rcvr->sk != sk)) {
330 /* In this case, the association moved from one socket to
331 * another. We are currently sitting on the backlog of the
332 * old socket, so we need to move.
333 * However, since we are here in the process context we
334 * need to take make sure that the user doesn't own
335 * the new socket when we process the packet.
336 * If the new socket is user-owned, queue the chunk to the
337 * backlog of the new socket without dropping any refs.
338 * Otherwise, we can safely push the chunk on the inqueue.
342 sctp_bh_lock_sock(sk);
344 if (sock_owned_by_user(sk)) {
345 if (sk_add_backlog(sk, skb))
346 sctp_chunk_free(chunk);
350 sctp_inq_push(inqueue, chunk);
352 sctp_bh_unlock_sock(sk);
354 /* If the chunk was backloged again, don't drop refs */
358 sctp_inq_push(inqueue, chunk);
362 /* Release the refs we took in sctp_add_backlog */
363 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
364 sctp_association_put(sctp_assoc(rcvr));
365 else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
366 sctp_endpoint_put(sctp_ep(rcvr));
373 static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb)
375 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
376 struct sctp_ep_common *rcvr = chunk->rcvr;
379 ret = sk_add_backlog(sk, skb);
381 /* Hold the assoc/ep while hanging on the backlog queue.
382 * This way, we know structures we need will not disappear
385 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
386 sctp_association_hold(sctp_assoc(rcvr));
387 else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
388 sctp_endpoint_hold(sctp_ep(rcvr));
396 /* Handle icmp frag needed error. */
397 void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc,
398 struct sctp_transport *t, __u32 pmtu)
400 if (!t || (t->pathmtu <= pmtu))
403 if (sock_owned_by_user(sk)) {
404 asoc->pmtu_pending = 1;
409 if (t->param_flags & SPP_PMTUD_ENABLE) {
410 /* Update transports view of the MTU */
411 sctp_transport_update_pmtu(t, pmtu);
413 /* Update association pmtu. */
414 sctp_assoc_sync_pmtu(asoc);
417 /* Retransmit with the new pmtu setting.
418 * Normally, if PMTU discovery is disabled, an ICMP Fragmentation
419 * Needed will never be sent, but if a message was sent before
420 * PMTU discovery was disabled that was larger than the PMTU, it
421 * would not be fragmented, so it must be re-transmitted fragmented.
423 sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD);
427 * SCTP Implementer's Guide, 2.37 ICMP handling procedures
429 * ICMP8) If the ICMP code is a "Unrecognized next header type encountered"
430 * or a "Protocol Unreachable" treat this message as an abort
431 * with the T bit set.
433 * This function sends an event to the state machine, which will abort the
437 void sctp_icmp_proto_unreachable(struct sock *sk,
438 struct sctp_association *asoc,
439 struct sctp_transport *t)
441 SCTP_DEBUG_PRINTK("%s\n", __func__);
443 sctp_do_sm(SCTP_EVENT_T_OTHER,
444 SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH),
445 asoc->state, asoc->ep, asoc, t,
450 /* Common lookup code for icmp/icmpv6 error handler. */
451 struct sock *sctp_err_lookup(int family, struct sk_buff *skb,
452 struct sctphdr *sctphdr,
453 struct sctp_association **app,
454 struct sctp_transport **tpp)
456 union sctp_addr saddr;
457 union sctp_addr daddr;
459 struct sock *sk = NULL;
460 struct sctp_association *asoc;
461 struct sctp_transport *transport = NULL;
462 struct sctp_init_chunk *chunkhdr;
463 __u32 vtag = ntohl(sctphdr->vtag);
464 int len = skb->len - ((void *)sctphdr - (void *)skb->data);
466 *app = NULL; *tpp = NULL;
468 af = sctp_get_af_specific(family);
473 /* Initialize local addresses for lookups. */
474 af->from_skb(&saddr, skb, 1);
475 af->from_skb(&daddr, skb, 0);
477 /* Look for an association that matches the incoming ICMP error
480 asoc = __sctp_lookup_association(&saddr, &daddr, &transport);
486 /* RFC 4960, Appendix C. ICMP Handling
488 * ICMP6) An implementation MUST validate that the Verification Tag
489 * contained in the ICMP message matches the Verification Tag of
490 * the peer. If the Verification Tag is not 0 and does NOT
491 * match, discard the ICMP message. If it is 0 and the ICMP
492 * message contains enough bytes to verify that the chunk type is
493 * an INIT chunk and that the Initiate Tag matches the tag of the
494 * peer, continue with ICMP7. If the ICMP message is too short
495 * or the chunk type or the Initiate Tag does not match, silently
496 * discard the packet.
499 chunkhdr = (struct sctp_init_chunk *)((void *)sctphdr
500 + sizeof(struct sctphdr));
501 if (len < sizeof(struct sctphdr) + sizeof(sctp_chunkhdr_t)
503 chunkhdr->chunk_hdr.type != SCTP_CID_INIT ||
504 ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag) {
507 } else if (vtag != asoc->c.peer_vtag) {
511 sctp_bh_lock_sock(sk);
513 /* If too many ICMPs get dropped on busy
514 * servers this needs to be solved differently.
516 if (sock_owned_by_user(sk))
517 NET_INC_STATS_BH(&init_net, LINUX_MIB_LOCKDROPPEDICMPS);
525 sctp_association_put(asoc);
529 /* Common cleanup code for icmp/icmpv6 error handler. */
530 void sctp_err_finish(struct sock *sk, struct sctp_association *asoc)
532 sctp_bh_unlock_sock(sk);
534 sctp_association_put(asoc);
538 * This routine is called by the ICMP module when it gets some
539 * sort of error condition. If err < 0 then the socket should
540 * be closed and the error returned to the user. If err > 0
541 * it's just the icmp type << 8 | icmp code. After adjustment
542 * header points to the first 8 bytes of the sctp header. We need
543 * to find the appropriate port.
545 * The locking strategy used here is very "optimistic". When
546 * someone else accesses the socket the ICMP is just dropped
547 * and for some paths there is no check at all.
548 * A more general error queue to queue errors for later handling
549 * is probably better.
552 void sctp_v4_err(struct sk_buff *skb, __u32 info)
554 struct iphdr *iph = (struct iphdr *)skb->data;
555 const int ihlen = iph->ihl * 4;
556 const int type = icmp_hdr(skb)->type;
557 const int code = icmp_hdr(skb)->code;
559 struct sctp_association *asoc = NULL;
560 struct sctp_transport *transport;
561 struct inet_sock *inet;
562 sk_buff_data_t saveip, savesctp;
565 if (skb->len < ihlen + 8) {
566 ICMP_INC_STATS_BH(&init_net, ICMP_MIB_INERRORS);
570 /* Fix up skb to look at the embedded net header. */
571 saveip = skb->network_header;
572 savesctp = skb->transport_header;
573 skb_reset_network_header(skb);
574 skb_set_transport_header(skb, ihlen);
575 sk = sctp_err_lookup(AF_INET, skb, sctp_hdr(skb), &asoc, &transport);
576 /* Put back, the original values. */
577 skb->network_header = saveip;
578 skb->transport_header = savesctp;
580 ICMP_INC_STATS_BH(&init_net, ICMP_MIB_INERRORS);
583 /* Warning: The sock lock is held. Remember to call
588 case ICMP_PARAMETERPROB:
591 case ICMP_DEST_UNREACH:
592 if (code > NR_ICMP_UNREACH)
595 /* PMTU discovery (RFC1191) */
596 if (ICMP_FRAG_NEEDED == code) {
597 sctp_icmp_frag_needed(sk, asoc, transport, info);
601 if (ICMP_PROT_UNREACH == code) {
602 sctp_icmp_proto_unreachable(sk, asoc,
607 err = icmp_err_convert[code].errno;
609 case ICMP_TIME_EXCEEDED:
610 /* Ignore any time exceeded errors due to fragment reassembly
613 if (ICMP_EXC_FRAGTIME == code)
623 if (!sock_owned_by_user(sk) && inet->recverr) {
625 sk->sk_error_report(sk);
626 } else { /* Only an error on timeout */
627 sk->sk_err_soft = err;
631 sctp_err_finish(sk, asoc);
635 * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
637 * This function scans all the chunks in the OOTB packet to determine if
638 * the packet should be discarded right away. If a response might be needed
639 * for this packet, or, if further processing is possible, the packet will
640 * be queued to a proper inqueue for the next phase of handling.
643 * Return 0 - If further processing is needed.
644 * Return 1 - If the packet can be discarded right away.
646 static int sctp_rcv_ootb(struct sk_buff *skb)
652 ch = (sctp_chunkhdr_t *) skb->data;
654 /* Scan through all the chunks in the packet. */
656 /* Break out if chunk length is less then minimal. */
657 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
660 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
661 if (ch_end > skb_tail_pointer(skb))
664 /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the
665 * receiver MUST silently discard the OOTB packet and take no
668 if (SCTP_CID_ABORT == ch->type)
671 /* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE
672 * chunk, the receiver should silently discard the packet
673 * and take no further action.
675 if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type)
679 * This will discard packets with INIT chunk bundled as
680 * subsequent chunks in the packet. When INIT is first,
681 * the normal INIT processing will discard the chunk.
683 if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data)
686 /* RFC 8.4, 7) If the packet contains a "Stale cookie" ERROR
687 * or a COOKIE ACK the SCTP Packet should be silently
690 if (SCTP_CID_COOKIE_ACK == ch->type)
693 if (SCTP_CID_ERROR == ch->type) {
694 sctp_walk_errors(err, ch) {
695 if (SCTP_ERROR_STALE_COOKIE == err->cause)
700 ch = (sctp_chunkhdr_t *) ch_end;
701 } while (ch_end < skb_tail_pointer(skb));
709 /* Insert endpoint into the hash table. */
710 static void __sctp_hash_endpoint(struct sctp_endpoint *ep)
712 struct sctp_ep_common *epb;
713 struct sctp_hashbucket *head;
717 epb->hashent = sctp_ep_hashfn(epb->bind_addr.port);
718 head = &sctp_ep_hashtable[epb->hashent];
720 sctp_write_lock(&head->lock);
721 hlist_add_head(&epb->node, &head->chain);
722 sctp_write_unlock(&head->lock);
725 /* Add an endpoint to the hash. Local BH-safe. */
726 void sctp_hash_endpoint(struct sctp_endpoint *ep)
728 sctp_local_bh_disable();
729 __sctp_hash_endpoint(ep);
730 sctp_local_bh_enable();
733 /* Remove endpoint from the hash table. */
734 static void __sctp_unhash_endpoint(struct sctp_endpoint *ep)
736 struct sctp_hashbucket *head;
737 struct sctp_ep_common *epb;
741 if (hlist_unhashed(&epb->node))
744 epb->hashent = sctp_ep_hashfn(epb->bind_addr.port);
746 head = &sctp_ep_hashtable[epb->hashent];
748 sctp_write_lock(&head->lock);
749 __hlist_del(&epb->node);
750 sctp_write_unlock(&head->lock);
753 /* Remove endpoint from the hash. Local BH-safe. */
754 void sctp_unhash_endpoint(struct sctp_endpoint *ep)
756 sctp_local_bh_disable();
757 __sctp_unhash_endpoint(ep);
758 sctp_local_bh_enable();
761 /* Look up an endpoint. */
762 static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr)
764 struct sctp_hashbucket *head;
765 struct sctp_ep_common *epb;
766 struct sctp_endpoint *ep;
767 struct hlist_node *node;
770 hash = sctp_ep_hashfn(ntohs(laddr->v4.sin_port));
771 head = &sctp_ep_hashtable[hash];
772 read_lock(&head->lock);
773 sctp_for_each_hentry(epb, node, &head->chain) {
775 if (sctp_endpoint_is_match(ep, laddr))
779 ep = sctp_sk((sctp_get_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 sctp_ep_common *epb;
791 struct sctp_hashbucket *head;
795 /* Calculate which chain this entry will belong to. */
796 epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port, asoc->peer.port);
798 head = &sctp_assoc_hashtable[epb->hashent];
800 sctp_write_lock(&head->lock);
801 hlist_add_head(&epb->node, &head->chain);
802 sctp_write_unlock(&head->lock);
805 /* Add an association to the hash. Local BH-safe. */
806 void sctp_hash_established(struct sctp_association *asoc)
811 sctp_local_bh_disable();
812 __sctp_hash_established(asoc);
813 sctp_local_bh_enable();
816 /* Remove association from the hash table. */
817 static void __sctp_unhash_established(struct sctp_association *asoc)
819 struct sctp_hashbucket *head;
820 struct sctp_ep_common *epb;
824 epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port,
827 head = &sctp_assoc_hashtable[epb->hashent];
829 sctp_write_lock(&head->lock);
830 __hlist_del(&epb->node);
831 sctp_write_unlock(&head->lock);
834 /* Remove association from the hash table. Local BH-safe. */
835 void sctp_unhash_established(struct sctp_association *asoc)
840 sctp_local_bh_disable();
841 __sctp_unhash_established(asoc);
842 sctp_local_bh_enable();
845 /* Look up an association. */
846 static struct sctp_association *__sctp_lookup_association(
847 const union sctp_addr *local,
848 const union sctp_addr *peer,
849 struct sctp_transport **pt)
851 struct sctp_hashbucket *head;
852 struct sctp_ep_common *epb;
853 struct sctp_association *asoc;
854 struct sctp_transport *transport;
855 struct hlist_node *node;
858 /* Optimize here for direct hit, only listening connections can
859 * have wildcards anyways.
861 hash = sctp_assoc_hashfn(ntohs(local->v4.sin_port), ntohs(peer->v4.sin_port));
862 head = &sctp_assoc_hashtable[hash];
863 read_lock(&head->lock);
864 sctp_for_each_hentry(epb, node, &head->chain) {
865 asoc = sctp_assoc(epb);
866 transport = sctp_assoc_is_match(asoc, local, peer);
871 read_unlock(&head->lock);
877 sctp_association_hold(asoc);
878 read_unlock(&head->lock);
882 /* Look up an association. BH-safe. */
884 struct sctp_association *sctp_lookup_association(const union sctp_addr *laddr,
885 const union sctp_addr *paddr,
886 struct sctp_transport **transportp)
888 struct sctp_association *asoc;
890 sctp_local_bh_disable();
891 asoc = __sctp_lookup_association(laddr, paddr, transportp);
892 sctp_local_bh_enable();
897 /* Is there an association matching the given local and peer addresses? */
898 int sctp_has_association(const union sctp_addr *laddr,
899 const union sctp_addr *paddr)
901 struct sctp_association *asoc;
902 struct sctp_transport *transport;
904 if ((asoc = sctp_lookup_association(laddr, paddr, &transport))) {
905 sctp_association_put(asoc);
913 * SCTP Implementors Guide, 2.18 Handling of address
914 * parameters within the INIT or INIT-ACK.
916 * D) When searching for a matching TCB upon reception of an INIT
917 * or INIT-ACK chunk the receiver SHOULD use not only the
918 * source address of the packet (containing the INIT or
919 * INIT-ACK) but the receiver SHOULD also use all valid
920 * address parameters contained within the chunk.
922 * 2.18.3 Solution description
924 * This new text clearly specifies to an implementor the need
925 * to look within the INIT or INIT-ACK. Any implementation that
926 * does not do this, may not be able to establish associations
927 * in certain circumstances.
930 static struct sctp_association *__sctp_rcv_init_lookup(struct sk_buff *skb,
931 const union sctp_addr *laddr, struct sctp_transport **transportp)
933 struct sctp_association *asoc;
934 union sctp_addr addr;
935 union sctp_addr *paddr = &addr;
936 struct sctphdr *sh = sctp_hdr(skb);
938 union sctp_params params;
939 sctp_init_chunk_t *init;
940 struct sctp_transport *transport;
943 ch = (sctp_chunkhdr_t *) skb->data;
946 * This code will NOT touch anything inside the chunk--it is
947 * strictly READ-ONLY.
949 * RFC 2960 3 SCTP packet Format
951 * Multiple chunks can be bundled into one SCTP packet up to
952 * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN
953 * COMPLETE chunks. These chunks MUST NOT be bundled with any
954 * other chunk in a packet. See Section 6.10 for more details
958 /* Find the start of the TLVs and the end of the chunk. This is
959 * the region we search for address parameters.
961 init = (sctp_init_chunk_t *)skb->data;
963 /* Walk the parameters looking for embedded addresses. */
964 sctp_walk_params(params, init, init_hdr.params) {
966 /* Note: Ignoring hostname addresses. */
967 af = sctp_get_af_specific(param_type2af(params.p->type));
971 af->from_addr_param(paddr, params.addr, sh->source, 0);
973 asoc = __sctp_lookup_association(laddr, paddr, &transport);
981 /* ADD-IP, Section 5.2
982 * When an endpoint receives an ASCONF Chunk from the remote peer
983 * special procedures may be needed to identify the association the
984 * ASCONF Chunk is associated with. To properly find the association
985 * the following procedures SHOULD be followed:
987 * D2) If the association is not found, use the address found in the
988 * Address Parameter TLV combined with the port number found in the
989 * SCTP common header. If found proceed to rule D4.
991 * D2-ext) If more than one ASCONF Chunks are packed together, use the
992 * address found in the ASCONF Address Parameter TLV of each of the
993 * subsequent ASCONF Chunks. If found, proceed to rule D4.
995 static struct sctp_association *__sctp_rcv_asconf_lookup(
997 const union sctp_addr *laddr,
999 struct sctp_transport **transportp)
1001 sctp_addip_chunk_t *asconf = (struct sctp_addip_chunk *)ch;
1003 union sctp_addr_param *param;
1004 union sctp_addr paddr;
1006 /* Skip over the ADDIP header and find the Address parameter */
1007 param = (union sctp_addr_param *)(asconf + 1);
1009 af = sctp_get_af_specific(param_type2af(param->v4.param_hdr.type));
1013 af->from_addr_param(&paddr, param, peer_port, 0);
1015 return __sctp_lookup_association(laddr, &paddr, transportp);
1019 /* SCTP-AUTH, Section 6.3:
1020 * If the receiver does not find a STCB for a packet containing an AUTH
1021 * chunk as the first chunk and not a COOKIE-ECHO chunk as the second
1022 * chunk, it MUST use the chunks after the AUTH chunk to look up an existing
1025 * This means that any chunks that can help us identify the association need
1026 * to be looked at to find this assocation.
1028 static struct sctp_association *__sctp_rcv_walk_lookup(struct sk_buff *skb,
1029 const union sctp_addr *laddr,
1030 struct sctp_transport **transportp)
1032 struct sctp_association *asoc = NULL;
1033 sctp_chunkhdr_t *ch;
1035 unsigned int chunk_num = 1;
1038 /* Walk through the chunks looking for AUTH or ASCONF chunks
1039 * to help us find the association.
1041 ch = (sctp_chunkhdr_t *) skb->data;
1043 /* Break out if chunk length is less then minimal. */
1044 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
1047 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
1048 if (ch_end > skb_tail_pointer(skb))
1053 have_auth = chunk_num;
1056 case SCTP_CID_COOKIE_ECHO:
1057 /* If a packet arrives containing an AUTH chunk as
1058 * a first chunk, a COOKIE-ECHO chunk as the second
1059 * chunk, and possibly more chunks after them, and
1060 * the receiver does not have an STCB for that
1061 * packet, then authentication is based on
1062 * the contents of the COOKIE- ECHO chunk.
1064 if (have_auth == 1 && chunk_num == 2)
1068 case SCTP_CID_ASCONF:
1069 if (have_auth || sctp_addip_noauth)
1070 asoc = __sctp_rcv_asconf_lookup(ch, laddr,
1071 sctp_hdr(skb)->source,
1080 ch = (sctp_chunkhdr_t *) ch_end;
1082 } while (ch_end < skb_tail_pointer(skb));
1088 * There are circumstances when we need to look inside the SCTP packet
1089 * for information to help us find the association. Examples
1090 * include looking inside of INIT/INIT-ACK chunks or after the AUTH
1093 static struct sctp_association *__sctp_rcv_lookup_harder(struct sk_buff *skb,
1094 const union sctp_addr *laddr,
1095 struct sctp_transport **transportp)
1097 sctp_chunkhdr_t *ch;
1099 ch = (sctp_chunkhdr_t *) skb->data;
1101 /* The code below will attempt to walk the chunk and extract
1102 * parameter information. Before we do that, we need to verify
1103 * that the chunk length doesn't cause overflow. Otherwise, we'll
1106 if (WORD_ROUND(ntohs(ch->length)) > skb->len)
1109 /* If this is INIT/INIT-ACK look inside the chunk too. */
1112 case SCTP_CID_INIT_ACK:
1113 return __sctp_rcv_init_lookup(skb, laddr, transportp);
1117 return __sctp_rcv_walk_lookup(skb, laddr, transportp);
1125 /* Lookup an association for an inbound skb. */
1126 static struct sctp_association *__sctp_rcv_lookup(struct sk_buff *skb,
1127 const union sctp_addr *paddr,
1128 const union sctp_addr *laddr,
1129 struct sctp_transport **transportp)
1131 struct sctp_association *asoc;
1133 asoc = __sctp_lookup_association(laddr, paddr, transportp);
1135 /* Further lookup for INIT/INIT-ACK packets.
1136 * SCTP Implementors Guide, 2.18 Handling of address
1137 * parameters within the INIT or INIT-ACK.
1140 asoc = __sctp_rcv_lookup_harder(skb, laddr, transportp);