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 <linux-sctp@vger.kernel.org>
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 net *net,
71 const union sctp_addr *paddr,
72 const union sctp_addr *laddr,
73 struct sctp_transport **transportp);
74 static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(struct net *net,
75 const union sctp_addr *laddr);
76 static struct sctp_association *__sctp_lookup_association(
78 const union sctp_addr *local,
79 const union sctp_addr *peer,
80 struct sctp_transport **pt);
82 static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb);
85 /* Calculate the SCTP checksum of an SCTP packet. */
86 static inline int sctp_rcv_checksum(struct net *net, struct sk_buff *skb)
88 struct sctphdr *sh = sctp_hdr(skb);
89 __le32 cmp = sh->checksum;
90 __le32 val = sctp_compute_cksum(skb, 0);
93 /* CRC failure, dump it. */
94 SCTP_INC_STATS_BH(net, SCTP_MIB_CHECKSUMERRORS);
100 struct sctp_input_cb {
102 struct inet_skb_parm h4;
103 #if IS_ENABLED(CONFIG_IPV6)
104 struct inet6_skb_parm h6;
107 struct sctp_chunk *chunk;
109 #define SCTP_INPUT_CB(__skb) ((struct sctp_input_cb *)&((__skb)->cb[0]))
112 * This is the routine which IP calls when receiving an SCTP packet.
114 int sctp_rcv(struct sk_buff *skb)
117 struct sctp_association *asoc;
118 struct sctp_endpoint *ep = NULL;
119 struct sctp_ep_common *rcvr;
120 struct sctp_transport *transport = NULL;
121 struct sctp_chunk *chunk;
124 union sctp_addr dest;
127 struct net *net = dev_net(skb->dev);
129 if (skb->pkt_type!=PACKET_HOST)
132 SCTP_INC_STATS_BH(net, SCTP_MIB_INSCTPPACKS);
134 if (skb_linearize(skb))
139 /* Pull up the IP and SCTP headers. */
140 __skb_pull(skb, skb_transport_offset(skb));
141 if (skb->len < sizeof(struct sctphdr))
143 if (!sctp_checksum_disable && !skb_csum_unnecessary(skb) &&
144 sctp_rcv_checksum(net, skb) < 0)
147 skb_pull(skb, sizeof(struct sctphdr));
149 /* Make sure we at least have chunk headers worth of data left. */
150 if (skb->len < sizeof(struct sctp_chunkhdr))
153 family = ipver2af(ip_hdr(skb)->version);
154 af = sctp_get_af_specific(family);
158 /* Initialize local addresses for lookups. */
159 af->from_skb(&src, skb, 1);
160 af->from_skb(&dest, skb, 0);
162 /* If the packet is to or from a non-unicast address,
163 * silently discard the packet.
165 * This is not clearly defined in the RFC except in section
166 * 8.4 - OOTB handling. However, based on the book "Stream Control
167 * Transmission Protocol" 2.1, "It is important to note that the
168 * IP address of an SCTP transport address must be a routable
169 * unicast address. In other words, IP multicast addresses and
170 * IP broadcast addresses cannot be used in an SCTP transport
173 if (!af->addr_valid(&src, NULL, skb) ||
174 !af->addr_valid(&dest, NULL, skb))
177 asoc = __sctp_rcv_lookup(net, skb, &src, &dest, &transport);
180 ep = __sctp_rcv_lookup_endpoint(net, &dest);
182 /* Retrieve the common input handling substructure. */
183 rcvr = asoc ? &asoc->base : &ep->base;
187 * If a frame arrives on an interface and the receiving socket is
188 * bound to another interface, via SO_BINDTODEVICE, treat it as OOTB
190 if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb)))
193 sctp_association_put(asoc);
196 sctp_endpoint_put(ep);
199 sk = net->sctp.ctl_sock;
200 ep = sctp_sk(sk)->ep;
201 sctp_endpoint_hold(ep);
206 * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
207 * An SCTP packet is called an "out of the blue" (OOTB)
208 * packet if it is correctly formed, i.e., passed the
209 * receiver's checksum check, but the receiver is not
210 * able to identify the association to which this
214 if (sctp_rcv_ootb(skb)) {
215 SCTP_INC_STATS_BH(net, SCTP_MIB_OUTOFBLUES);
216 goto discard_release;
220 if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family))
221 goto discard_release;
224 if (sk_filter(sk, skb))
225 goto discard_release;
227 /* Create an SCTP packet structure. */
228 chunk = sctp_chunkify(skb, asoc, sk);
230 goto discard_release;
231 SCTP_INPUT_CB(skb)->chunk = chunk;
233 /* Remember what endpoint is to handle this packet. */
236 /* Remember the SCTP header. */
237 chunk->sctp_hdr = sh;
239 /* Set the source and destination addresses of the incoming chunk. */
240 sctp_init_addrs(chunk, &src, &dest);
242 /* Remember where we came from. */
243 chunk->transport = transport;
245 /* Acquire access to the sock lock. Note: We are safe from other
246 * bottom halves on this lock, but a user may be in the lock too,
247 * so check if it is busy.
249 sctp_bh_lock_sock(sk);
251 if (sk != rcvr->sk) {
252 /* Our cached sk is different from the rcvr->sk. This is
253 * because migrate()/accept() may have moved the association
254 * to a new socket and released all the sockets. So now we
255 * are holding a lock on the old socket while the user may
256 * be doing something with the new socket. Switch our veiw
259 sctp_bh_unlock_sock(sk);
261 sctp_bh_lock_sock(sk);
264 if (sock_owned_by_user(sk)) {
265 if (sctp_add_backlog(sk, skb)) {
266 sctp_bh_unlock_sock(sk);
267 sctp_chunk_free(chunk);
268 skb = NULL; /* sctp_chunk_free already freed the skb */
269 goto discard_release;
271 SCTP_INC_STATS_BH(net, SCTP_MIB_IN_PKT_BACKLOG);
273 SCTP_INC_STATS_BH(net, SCTP_MIB_IN_PKT_SOFTIRQ);
274 sctp_inq_push(&chunk->rcvr->inqueue, chunk);
277 sctp_bh_unlock_sock(sk);
279 /* Release the asoc/ep ref we took in the lookup calls. */
281 sctp_association_put(asoc);
283 sctp_endpoint_put(ep);
288 SCTP_INC_STATS_BH(net, SCTP_MIB_IN_PKT_DISCARDS);
293 /* Release the asoc/ep ref we took in the lookup calls. */
295 sctp_association_put(asoc);
297 sctp_endpoint_put(ep);
302 /* Process the backlog queue of the socket. Every skb on
303 * the backlog holds a ref on an association or endpoint.
304 * We hold this ref throughout the state machine to make
305 * sure that the structure we need is still around.
307 int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
309 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
310 struct sctp_inq *inqueue = &chunk->rcvr->inqueue;
311 struct sctp_ep_common *rcvr = NULL;
316 /* If the rcvr is dead then the association or endpoint
317 * has been deleted and we can safely drop the chunk
318 * and refs that we are holding.
321 sctp_chunk_free(chunk);
325 if (unlikely(rcvr->sk != sk)) {
326 /* In this case, the association moved from one socket to
327 * another. We are currently sitting on the backlog of the
328 * old socket, so we need to move.
329 * However, since we are here in the process context we
330 * need to take make sure that the user doesn't own
331 * the new socket when we process the packet.
332 * If the new socket is user-owned, queue the chunk to the
333 * backlog of the new socket without dropping any refs.
334 * Otherwise, we can safely push the chunk on the inqueue.
338 sctp_bh_lock_sock(sk);
340 if (sock_owned_by_user(sk)) {
341 if (sk_add_backlog(sk, skb, sk->sk_rcvbuf))
342 sctp_chunk_free(chunk);
346 sctp_inq_push(inqueue, chunk);
348 sctp_bh_unlock_sock(sk);
350 /* If the chunk was backloged again, don't drop refs */
354 sctp_inq_push(inqueue, chunk);
358 /* Release the refs we took in sctp_add_backlog */
359 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
360 sctp_association_put(sctp_assoc(rcvr));
361 else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
362 sctp_endpoint_put(sctp_ep(rcvr));
369 static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb)
371 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
372 struct sctp_ep_common *rcvr = chunk->rcvr;
375 ret = sk_add_backlog(sk, skb, sk->sk_rcvbuf);
377 /* Hold the assoc/ep while hanging on the backlog queue.
378 * This way, we know structures we need will not disappear
381 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
382 sctp_association_hold(sctp_assoc(rcvr));
383 else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
384 sctp_endpoint_hold(sctp_ep(rcvr));
392 /* Handle icmp frag needed error. */
393 void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc,
394 struct sctp_transport *t, __u32 pmtu)
396 if (!t || (t->pathmtu <= pmtu))
399 if (sock_owned_by_user(sk)) {
400 asoc->pmtu_pending = 1;
405 if (t->param_flags & SPP_PMTUD_ENABLE) {
406 /* Update transports view of the MTU */
407 sctp_transport_update_pmtu(sk, t, pmtu);
409 /* Update association pmtu. */
410 sctp_assoc_sync_pmtu(sk, asoc);
413 /* Retransmit with the new pmtu setting.
414 * Normally, if PMTU discovery is disabled, an ICMP Fragmentation
415 * Needed will never be sent, but if a message was sent before
416 * PMTU discovery was disabled that was larger than the PMTU, it
417 * would not be fragmented, so it must be re-transmitted fragmented.
419 sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD);
422 void sctp_icmp_redirect(struct sock *sk, struct sctp_transport *t,
425 struct dst_entry *dst;
429 dst = sctp_transport_dst_check(t);
431 dst->ops->redirect(dst, sk, skb);
435 * SCTP Implementer's Guide, 2.37 ICMP handling procedures
437 * ICMP8) If the ICMP code is a "Unrecognized next header type encountered"
438 * or a "Protocol Unreachable" treat this message as an abort
439 * with the T bit set.
441 * This function sends an event to the state machine, which will abort the
445 void sctp_icmp_proto_unreachable(struct sock *sk,
446 struct sctp_association *asoc,
447 struct sctp_transport *t)
449 if (sock_owned_by_user(sk)) {
450 if (timer_pending(&t->proto_unreach_timer))
453 if (!mod_timer(&t->proto_unreach_timer,
455 sctp_association_hold(asoc);
458 struct net *net = sock_net(sk);
460 pr_debug("%s: unrecognized next header type "
461 "encountered!\n", __func__);
463 if (del_timer(&t->proto_unreach_timer))
464 sctp_association_put(asoc);
466 sctp_do_sm(net, SCTP_EVENT_T_OTHER,
467 SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH),
468 asoc->state, asoc->ep, asoc, t,
473 /* Common lookup code for icmp/icmpv6 error handler. */
474 struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *skb,
475 struct sctphdr *sctphdr,
476 struct sctp_association **app,
477 struct sctp_transport **tpp)
479 union sctp_addr saddr;
480 union sctp_addr daddr;
482 struct sock *sk = NULL;
483 struct sctp_association *asoc;
484 struct sctp_transport *transport = NULL;
485 struct sctp_init_chunk *chunkhdr;
486 __u32 vtag = ntohl(sctphdr->vtag);
487 int len = skb->len - ((void *)sctphdr - (void *)skb->data);
489 *app = NULL; *tpp = NULL;
491 af = sctp_get_af_specific(family);
496 /* Initialize local addresses for lookups. */
497 af->from_skb(&saddr, skb, 1);
498 af->from_skb(&daddr, skb, 0);
500 /* Look for an association that matches the incoming ICMP error
503 asoc = __sctp_lookup_association(net, &saddr, &daddr, &transport);
509 /* RFC 4960, Appendix C. ICMP Handling
511 * ICMP6) An implementation MUST validate that the Verification Tag
512 * contained in the ICMP message matches the Verification Tag of
513 * the peer. If the Verification Tag is not 0 and does NOT
514 * match, discard the ICMP message. If it is 0 and the ICMP
515 * message contains enough bytes to verify that the chunk type is
516 * an INIT chunk and that the Initiate Tag matches the tag of the
517 * peer, continue with ICMP7. If the ICMP message is too short
518 * or the chunk type or the Initiate Tag does not match, silently
519 * discard the packet.
522 chunkhdr = (void *)sctphdr + sizeof(struct sctphdr);
523 if (len < sizeof(struct sctphdr) + sizeof(sctp_chunkhdr_t)
525 chunkhdr->chunk_hdr.type != SCTP_CID_INIT ||
526 ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag) {
529 } else if (vtag != asoc->c.peer_vtag) {
533 sctp_bh_lock_sock(sk);
535 /* If too many ICMPs get dropped on busy
536 * servers this needs to be solved differently.
538 if (sock_owned_by_user(sk))
539 NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
547 sctp_association_put(asoc);
551 /* Common cleanup code for icmp/icmpv6 error handler. */
552 void sctp_err_finish(struct sock *sk, struct sctp_association *asoc)
554 sctp_bh_unlock_sock(sk);
556 sctp_association_put(asoc);
560 * This routine is called by the ICMP module when it gets some
561 * sort of error condition. If err < 0 then the socket should
562 * be closed and the error returned to the user. If err > 0
563 * it's just the icmp type << 8 | icmp code. After adjustment
564 * header points to the first 8 bytes of the sctp header. We need
565 * to find the appropriate port.
567 * The locking strategy used here is very "optimistic". When
568 * someone else accesses the socket the ICMP is just dropped
569 * and for some paths there is no check at all.
570 * A more general error queue to queue errors for later handling
571 * is probably better.
574 void sctp_v4_err(struct sk_buff *skb, __u32 info)
576 const struct iphdr *iph = (const struct iphdr *)skb->data;
577 const int ihlen = iph->ihl * 4;
578 const int type = icmp_hdr(skb)->type;
579 const int code = icmp_hdr(skb)->code;
581 struct sctp_association *asoc = NULL;
582 struct sctp_transport *transport;
583 struct inet_sock *inet;
584 __u16 saveip, savesctp;
586 struct net *net = dev_net(skb->dev);
588 if (skb->len < ihlen + 8) {
589 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
593 /* Fix up skb to look at the embedded net header. */
594 saveip = skb->network_header;
595 savesctp = skb->transport_header;
596 skb_reset_network_header(skb);
597 skb_set_transport_header(skb, ihlen);
598 sk = sctp_err_lookup(net, AF_INET, skb, sctp_hdr(skb), &asoc, &transport);
599 /* Put back, the original values. */
600 skb->network_header = saveip;
601 skb->transport_header = savesctp;
603 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
606 /* Warning: The sock lock is held. Remember to call
611 case ICMP_PARAMETERPROB:
614 case ICMP_DEST_UNREACH:
615 if (code > NR_ICMP_UNREACH)
618 /* PMTU discovery (RFC1191) */
619 if (ICMP_FRAG_NEEDED == code) {
620 sctp_icmp_frag_needed(sk, asoc, transport, info);
624 if (ICMP_PROT_UNREACH == code) {
625 sctp_icmp_proto_unreachable(sk, asoc,
630 err = icmp_err_convert[code].errno;
632 case ICMP_TIME_EXCEEDED:
633 /* Ignore any time exceeded errors due to fragment reassembly
636 if (ICMP_EXC_FRAGTIME == code)
642 sctp_icmp_redirect(sk, transport, skb);
650 if (!sock_owned_by_user(sk) && inet->recverr) {
652 sk->sk_error_report(sk);
653 } else { /* Only an error on timeout */
654 sk->sk_err_soft = err;
658 sctp_err_finish(sk, asoc);
662 * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
664 * This function scans all the chunks in the OOTB packet to determine if
665 * the packet should be discarded right away. If a response might be needed
666 * for this packet, or, if further processing is possible, the packet will
667 * be queued to a proper inqueue for the next phase of handling.
670 * Return 0 - If further processing is needed.
671 * Return 1 - If the packet can be discarded right away.
673 static int sctp_rcv_ootb(struct sk_buff *skb)
678 ch = (sctp_chunkhdr_t *) skb->data;
680 /* Scan through all the chunks in the packet. */
682 /* Break out if chunk length is less then minimal. */
683 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
686 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
687 if (ch_end > skb_tail_pointer(skb))
690 /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the
691 * receiver MUST silently discard the OOTB packet and take no
694 if (SCTP_CID_ABORT == ch->type)
697 /* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE
698 * chunk, the receiver should silently discard the packet
699 * and take no further action.
701 if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type)
705 * This will discard packets with INIT chunk bundled as
706 * subsequent chunks in the packet. When INIT is first,
707 * the normal INIT processing will discard the chunk.
709 if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data)
712 ch = (sctp_chunkhdr_t *) ch_end;
713 } while (ch_end < skb_tail_pointer(skb));
721 /* Insert endpoint into the hash table. */
722 static void __sctp_hash_endpoint(struct sctp_endpoint *ep)
724 struct net *net = sock_net(ep->base.sk);
725 struct sctp_ep_common *epb;
726 struct sctp_hashbucket *head;
730 epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port);
731 head = &sctp_ep_hashtable[epb->hashent];
733 sctp_write_lock(&head->lock);
734 hlist_add_head(&epb->node, &head->chain);
735 sctp_write_unlock(&head->lock);
738 /* Add an endpoint to the hash. Local BH-safe. */
739 void sctp_hash_endpoint(struct sctp_endpoint *ep)
741 sctp_local_bh_disable();
742 __sctp_hash_endpoint(ep);
743 sctp_local_bh_enable();
746 /* Remove endpoint from the hash table. */
747 static void __sctp_unhash_endpoint(struct sctp_endpoint *ep)
749 struct net *net = sock_net(ep->base.sk);
750 struct sctp_hashbucket *head;
751 struct sctp_ep_common *epb;
755 epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port);
757 head = &sctp_ep_hashtable[epb->hashent];
759 sctp_write_lock(&head->lock);
760 hlist_del_init(&epb->node);
761 sctp_write_unlock(&head->lock);
764 /* Remove endpoint from the hash. Local BH-safe. */
765 void sctp_unhash_endpoint(struct sctp_endpoint *ep)
767 sctp_local_bh_disable();
768 __sctp_unhash_endpoint(ep);
769 sctp_local_bh_enable();
772 /* Look up an endpoint. */
773 static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(struct net *net,
774 const union sctp_addr *laddr)
776 struct sctp_hashbucket *head;
777 struct sctp_ep_common *epb;
778 struct sctp_endpoint *ep;
781 hash = sctp_ep_hashfn(net, ntohs(laddr->v4.sin_port));
782 head = &sctp_ep_hashtable[hash];
783 read_lock(&head->lock);
784 sctp_for_each_hentry(epb, &head->chain) {
786 if (sctp_endpoint_is_match(ep, net, laddr))
790 ep = sctp_sk(net->sctp.ctl_sock)->ep;
793 sctp_endpoint_hold(ep);
794 read_unlock(&head->lock);
798 /* Insert association into the hash table. */
799 static void __sctp_hash_established(struct sctp_association *asoc)
801 struct net *net = sock_net(asoc->base.sk);
802 struct sctp_ep_common *epb;
803 struct sctp_hashbucket *head;
807 /* Calculate which chain this entry will belong to. */
808 epb->hashent = sctp_assoc_hashfn(net, epb->bind_addr.port,
811 head = &sctp_assoc_hashtable[epb->hashent];
813 sctp_write_lock(&head->lock);
814 hlist_add_head(&epb->node, &head->chain);
815 sctp_write_unlock(&head->lock);
818 /* Add an association to the hash. Local BH-safe. */
819 void sctp_hash_established(struct sctp_association *asoc)
824 sctp_local_bh_disable();
825 __sctp_hash_established(asoc);
826 sctp_local_bh_enable();
829 /* Remove association from the hash table. */
830 static void __sctp_unhash_established(struct sctp_association *asoc)
832 struct net *net = sock_net(asoc->base.sk);
833 struct sctp_hashbucket *head;
834 struct sctp_ep_common *epb;
838 epb->hashent = sctp_assoc_hashfn(net, epb->bind_addr.port,
841 head = &sctp_assoc_hashtable[epb->hashent];
843 sctp_write_lock(&head->lock);
844 hlist_del_init(&epb->node);
845 sctp_write_unlock(&head->lock);
848 /* Remove association from the hash table. Local BH-safe. */
849 void sctp_unhash_established(struct sctp_association *asoc)
854 sctp_local_bh_disable();
855 __sctp_unhash_established(asoc);
856 sctp_local_bh_enable();
859 /* Look up an association. */
860 static struct sctp_association *__sctp_lookup_association(
862 const union sctp_addr *local,
863 const union sctp_addr *peer,
864 struct sctp_transport **pt)
866 struct sctp_hashbucket *head;
867 struct sctp_ep_common *epb;
868 struct sctp_association *asoc;
869 struct sctp_transport *transport;
872 /* Optimize here for direct hit, only listening connections can
873 * have wildcards anyways.
875 hash = sctp_assoc_hashfn(net, ntohs(local->v4.sin_port),
876 ntohs(peer->v4.sin_port));
877 head = &sctp_assoc_hashtable[hash];
878 read_lock(&head->lock);
879 sctp_for_each_hentry(epb, &head->chain) {
880 asoc = sctp_assoc(epb);
881 transport = sctp_assoc_is_match(asoc, net, local, peer);
886 read_unlock(&head->lock);
892 sctp_association_hold(asoc);
893 read_unlock(&head->lock);
897 /* Look up an association. BH-safe. */
899 struct sctp_association *sctp_lookup_association(struct net *net,
900 const union sctp_addr *laddr,
901 const union sctp_addr *paddr,
902 struct sctp_transport **transportp)
904 struct sctp_association *asoc;
906 sctp_local_bh_disable();
907 asoc = __sctp_lookup_association(net, laddr, paddr, transportp);
908 sctp_local_bh_enable();
913 /* Is there an association matching the given local and peer addresses? */
914 int sctp_has_association(struct net *net,
915 const union sctp_addr *laddr,
916 const union sctp_addr *paddr)
918 struct sctp_association *asoc;
919 struct sctp_transport *transport;
921 if ((asoc = sctp_lookup_association(net, laddr, paddr, &transport))) {
922 sctp_association_put(asoc);
930 * SCTP Implementors Guide, 2.18 Handling of address
931 * parameters within the INIT or INIT-ACK.
933 * D) When searching for a matching TCB upon reception of an INIT
934 * or INIT-ACK chunk the receiver SHOULD use not only the
935 * source address of the packet (containing the INIT or
936 * INIT-ACK) but the receiver SHOULD also use all valid
937 * address parameters contained within the chunk.
939 * 2.18.3 Solution description
941 * This new text clearly specifies to an implementor the need
942 * to look within the INIT or INIT-ACK. Any implementation that
943 * does not do this, may not be able to establish associations
944 * in certain circumstances.
947 static struct sctp_association *__sctp_rcv_init_lookup(struct net *net,
949 const union sctp_addr *laddr, struct sctp_transport **transportp)
951 struct sctp_association *asoc;
952 union sctp_addr addr;
953 union sctp_addr *paddr = &addr;
954 struct sctphdr *sh = sctp_hdr(skb);
955 union sctp_params params;
956 sctp_init_chunk_t *init;
957 struct sctp_transport *transport;
961 * This code will NOT touch anything inside the chunk--it is
962 * strictly READ-ONLY.
964 * RFC 2960 3 SCTP packet Format
966 * Multiple chunks can be bundled into one SCTP packet up to
967 * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN
968 * COMPLETE chunks. These chunks MUST NOT be bundled with any
969 * other chunk in a packet. See Section 6.10 for more details
973 /* Find the start of the TLVs and the end of the chunk. This is
974 * the region we search for address parameters.
976 init = (sctp_init_chunk_t *)skb->data;
978 /* Walk the parameters looking for embedded addresses. */
979 sctp_walk_params(params, init, init_hdr.params) {
981 /* Note: Ignoring hostname addresses. */
982 af = sctp_get_af_specific(param_type2af(params.p->type));
986 af->from_addr_param(paddr, params.addr, sh->source, 0);
988 asoc = __sctp_lookup_association(net, laddr, paddr, &transport);
996 /* ADD-IP, Section 5.2
997 * When an endpoint receives an ASCONF Chunk from the remote peer
998 * special procedures may be needed to identify the association the
999 * ASCONF Chunk is associated with. To properly find the association
1000 * the following procedures SHOULD be followed:
1002 * D2) If the association is not found, use the address found in the
1003 * Address Parameter TLV combined with the port number found in the
1004 * SCTP common header. If found proceed to rule D4.
1006 * D2-ext) If more than one ASCONF Chunks are packed together, use the
1007 * address found in the ASCONF Address Parameter TLV of each of the
1008 * subsequent ASCONF Chunks. If found, proceed to rule D4.
1010 static struct sctp_association *__sctp_rcv_asconf_lookup(
1012 sctp_chunkhdr_t *ch,
1013 const union sctp_addr *laddr,
1015 struct sctp_transport **transportp)
1017 sctp_addip_chunk_t *asconf = (struct sctp_addip_chunk *)ch;
1019 union sctp_addr_param *param;
1020 union sctp_addr paddr;
1022 /* Skip over the ADDIP header and find the Address parameter */
1023 param = (union sctp_addr_param *)(asconf + 1);
1025 af = sctp_get_af_specific(param_type2af(param->p.type));
1029 af->from_addr_param(&paddr, param, peer_port, 0);
1031 return __sctp_lookup_association(net, laddr, &paddr, transportp);
1035 /* SCTP-AUTH, Section 6.3:
1036 * If the receiver does not find a STCB for a packet containing an AUTH
1037 * chunk as the first chunk and not a COOKIE-ECHO chunk as the second
1038 * chunk, it MUST use the chunks after the AUTH chunk to look up an existing
1041 * This means that any chunks that can help us identify the association need
1042 * to be looked at to find this association.
1044 static struct sctp_association *__sctp_rcv_walk_lookup(struct net *net,
1045 struct sk_buff *skb,
1046 const union sctp_addr *laddr,
1047 struct sctp_transport **transportp)
1049 struct sctp_association *asoc = NULL;
1050 sctp_chunkhdr_t *ch;
1052 unsigned int chunk_num = 1;
1055 /* Walk through the chunks looking for AUTH or ASCONF chunks
1056 * to help us find the association.
1058 ch = (sctp_chunkhdr_t *) skb->data;
1060 /* Break out if chunk length is less then minimal. */
1061 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
1064 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
1065 if (ch_end > skb_tail_pointer(skb))
1070 have_auth = chunk_num;
1073 case SCTP_CID_COOKIE_ECHO:
1074 /* If a packet arrives containing an AUTH chunk as
1075 * a first chunk, a COOKIE-ECHO chunk as the second
1076 * chunk, and possibly more chunks after them, and
1077 * the receiver does not have an STCB for that
1078 * packet, then authentication is based on
1079 * the contents of the COOKIE- ECHO chunk.
1081 if (have_auth == 1 && chunk_num == 2)
1085 case SCTP_CID_ASCONF:
1086 if (have_auth || net->sctp.addip_noauth)
1087 asoc = __sctp_rcv_asconf_lookup(
1089 sctp_hdr(skb)->source,
1098 ch = (sctp_chunkhdr_t *) ch_end;
1100 } while (ch_end < skb_tail_pointer(skb));
1106 * There are circumstances when we need to look inside the SCTP packet
1107 * for information to help us find the association. Examples
1108 * include looking inside of INIT/INIT-ACK chunks or after the AUTH
1111 static struct sctp_association *__sctp_rcv_lookup_harder(struct net *net,
1112 struct sk_buff *skb,
1113 const union sctp_addr *laddr,
1114 struct sctp_transport **transportp)
1116 sctp_chunkhdr_t *ch;
1118 ch = (sctp_chunkhdr_t *) skb->data;
1120 /* The code below will attempt to walk the chunk and extract
1121 * parameter information. Before we do that, we need to verify
1122 * that the chunk length doesn't cause overflow. Otherwise, we'll
1125 if (WORD_ROUND(ntohs(ch->length)) > skb->len)
1128 /* If this is INIT/INIT-ACK look inside the chunk too. */
1131 case SCTP_CID_INIT_ACK:
1132 return __sctp_rcv_init_lookup(net, skb, laddr, transportp);
1136 return __sctp_rcv_walk_lookup(net, skb, laddr, transportp);
1144 /* Lookup an association for an inbound skb. */
1145 static struct sctp_association *__sctp_rcv_lookup(struct net *net,
1146 struct sk_buff *skb,
1147 const union sctp_addr *paddr,
1148 const union sctp_addr *laddr,
1149 struct sctp_transport **transportp)
1151 struct sctp_association *asoc;
1153 asoc = __sctp_lookup_association(net, laddr, paddr, transportp);
1155 /* Further lookup for INIT/INIT-ACK packets.
1156 * SCTP Implementors Guide, 2.18 Handling of address
1157 * parameters within the INIT or INIT-ACK.
1160 asoc = __sctp_rcv_lookup_harder(net, skb, laddr, transportp);