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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
8 *
9 * This file is part of the SCTP kernel implementation
10 *
11 * These functions handle all input from the IP layer into SCTP.
12 *
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)
17 * any later version.
18 *
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.
24 *
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/>.
28 *
29 * Please send any bug reports or fixes you make to the
30 * email address(es):
31 * lksctp developers <linux-sctp@vger.kernel.org>
32 *
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>
42 */
43
44#include <linux/types.h>
45#include <linux/list.h> /* For struct list_head */
46#include <linux/socket.h>
47#include <linux/ip.h>
48#include <linux/time.h> /* For struct timeval */
49#include <linux/slab.h>
50#include <net/ip.h>
51#include <net/icmp.h>
52#include <net/snmp.h>
53#include <net/sock.h>
54#include <net/xfrm.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>
59
60/* Forward declarations for internal helpers. */
61static int sctp_rcv_ootb(struct sk_buff *);
62static struct sctp_association *__sctp_rcv_lookup(struct net *net,
63 struct sk_buff *skb,
64 const union sctp_addr *paddr,
65 const union sctp_addr *laddr,
66 struct sctp_transport **transportp);
67static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(struct net *net,
68 const union sctp_addr *laddr);
69static struct sctp_association *__sctp_lookup_association(
70 struct net *net,
71 const union sctp_addr *local,
72 const union sctp_addr *peer,
73 struct sctp_transport **pt);
74
75static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb);
76
77
78/* Calculate the SCTP checksum of an SCTP packet. */
79static inline int sctp_rcv_checksum(struct net *net, struct sk_buff *skb)
80{
81 struct sctphdr *sh = sctp_hdr(skb);
82 __le32 cmp = sh->checksum;
83 __le32 val = sctp_compute_cksum(skb, 0);
84
85 if (val != cmp) {
86 /* CRC failure, dump it. */
87 SCTP_INC_STATS_BH(net, SCTP_MIB_CHECKSUMERRORS);
88 return -1;
89 }
90 return 0;
91}
92
93struct sctp_input_cb {
94 union {
95 struct inet_skb_parm h4;
96#if IS_ENABLED(CONFIG_IPV6)
97 struct inet6_skb_parm h6;
98#endif
99 } header;
100 struct sctp_chunk *chunk;
101};
102#define SCTP_INPUT_CB(__skb) ((struct sctp_input_cb *)&((__skb)->cb[0]))
103
104/*
105 * This is the routine which IP calls when receiving an SCTP packet.
106 */
107int sctp_rcv(struct sk_buff *skb)
108{
109 struct sock *sk;
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;
115 struct sctphdr *sh;
116 union sctp_addr src;
117 union sctp_addr dest;
118 int family;
119 struct sctp_af *af;
120 struct net *net = dev_net(skb->dev);
121
122 if (skb->pkt_type != PACKET_HOST)
123 goto discard_it;
124
125 SCTP_INC_STATS_BH(net, SCTP_MIB_INSCTPPACKS);
126
127 if (skb_linearize(skb))
128 goto discard_it;
129
130 sh = sctp_hdr(skb);
131
132 /* Pull up the IP and SCTP headers. */
133 __skb_pull(skb, skb_transport_offset(skb));
134 if (skb->len < sizeof(struct sctphdr))
135 goto discard_it;
136 if (!sctp_checksum_disable && !skb_csum_unnecessary(skb) &&
137 sctp_rcv_checksum(net, skb) < 0)
138 goto discard_it;
139
140 skb_pull(skb, sizeof(struct sctphdr));
141
142 /* Make sure we at least have chunk headers worth of data left. */
143 if (skb->len < sizeof(struct sctp_chunkhdr))
144 goto discard_it;
145
146 family = ipver2af(ip_hdr(skb)->version);
147 af = sctp_get_af_specific(family);
148 if (unlikely(!af))
149 goto discard_it;
150
151 /* Initialize local addresses for lookups. */
152 af->from_skb(&src, skb, 1);
153 af->from_skb(&dest, skb, 0);
154
155 /* If the packet is to or from a non-unicast address,
156 * silently discard the packet.
157 *
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
164 * address."
165 */
166 if (!af->addr_valid(&src, NULL, skb) ||
167 !af->addr_valid(&dest, NULL, skb))
168 goto discard_it;
169
170 asoc = __sctp_rcv_lookup(net, skb, &src, &dest, &transport);
171
172 if (!asoc)
173 ep = __sctp_rcv_lookup_endpoint(net, &dest);
174
175 /* Retrieve the common input handling substructure. */
176 rcvr = asoc ? &asoc->base : &ep->base;
177 sk = rcvr->sk;
178
179 /*
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
182 */
183 if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb))) {
184 if (asoc) {
185 sctp_association_put(asoc);
186 asoc = NULL;
187 } else {
188 sctp_endpoint_put(ep);
189 ep = NULL;
190 }
191 sk = net->sctp.ctl_sock;
192 ep = sctp_sk(sk)->ep;
193 sctp_endpoint_hold(ep);
194 rcvr = &ep->base;
195 }
196
197 /*
198 * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
199 * An SCTP packet is called an "out of the blue" (OOTB)
200 * packet if it is correctly formed, i.e., passed the
201 * receiver's checksum check, but the receiver is not
202 * able to identify the association to which this
203 * packet belongs.
204 */
205 if (!asoc) {
206 if (sctp_rcv_ootb(skb)) {
207 SCTP_INC_STATS_BH(net, SCTP_MIB_OUTOFBLUES);
208 goto discard_release;
209 }
210 }
211
212 if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family))
213 goto discard_release;
214 nf_reset(skb);
215
216 if (sk_filter(sk, skb))
217 goto discard_release;
218
219 /* Create an SCTP packet structure. */
220 chunk = sctp_chunkify(skb, asoc, sk);
221 if (!chunk)
222 goto discard_release;
223 SCTP_INPUT_CB(skb)->chunk = chunk;
224
225 /* Remember what endpoint is to handle this packet. */
226 chunk->rcvr = rcvr;
227
228 /* Remember the SCTP header. */
229 chunk->sctp_hdr = sh;
230
231 /* Set the source and destination addresses of the incoming chunk. */
232 sctp_init_addrs(chunk, &src, &dest);
233
234 /* Remember where we came from. */
235 chunk->transport = transport;
236
237 /* Acquire access to the sock lock. Note: We are safe from other
238 * bottom halves on this lock, but a user may be in the lock too,
239 * so check if it is busy.
240 */
241 bh_lock_sock(sk);
242
243 if (sk != rcvr->sk) {
244 /* Our cached sk is different from the rcvr->sk. This is
245 * because migrate()/accept() may have moved the association
246 * to a new socket and released all the sockets. So now we
247 * are holding a lock on the old socket while the user may
248 * be doing something with the new socket. Switch our veiw
249 * of the current sk.
250 */
251 bh_unlock_sock(sk);
252 sk = rcvr->sk;
253 bh_lock_sock(sk);
254 }
255
256 if (sock_owned_by_user(sk)) {
257 if (sctp_add_backlog(sk, skb)) {
258 bh_unlock_sock(sk);
259 sctp_chunk_free(chunk);
260 skb = NULL; /* sctp_chunk_free already freed the skb */
261 goto discard_release;
262 }
263 SCTP_INC_STATS_BH(net, SCTP_MIB_IN_PKT_BACKLOG);
264 } else {
265 SCTP_INC_STATS_BH(net, SCTP_MIB_IN_PKT_SOFTIRQ);
266 sctp_inq_push(&chunk->rcvr->inqueue, chunk);
267 }
268
269 bh_unlock_sock(sk);
270
271 /* Release the asoc/ep ref we took in the lookup calls. */
272 if (asoc)
273 sctp_association_put(asoc);
274 else
275 sctp_endpoint_put(ep);
276
277 return 0;
278
279discard_it:
280 SCTP_INC_STATS_BH(net, SCTP_MIB_IN_PKT_DISCARDS);
281 kfree_skb(skb);
282 return 0;
283
284discard_release:
285 /* Release the asoc/ep ref we took in the lookup calls. */
286 if (asoc)
287 sctp_association_put(asoc);
288 else
289 sctp_endpoint_put(ep);
290
291 goto discard_it;
292}
293
294/* Process the backlog queue of the socket. Every skb on
295 * the backlog holds a ref on an association or endpoint.
296 * We hold this ref throughout the state machine to make
297 * sure that the structure we need is still around.
298 */
299int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
300{
301 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
302 struct sctp_inq *inqueue = &chunk->rcvr->inqueue;
303 struct sctp_ep_common *rcvr = NULL;
304 int backloged = 0;
305
306 rcvr = chunk->rcvr;
307
308 /* If the rcvr is dead then the association or endpoint
309 * has been deleted and we can safely drop the chunk
310 * and refs that we are holding.
311 */
312 if (rcvr->dead) {
313 sctp_chunk_free(chunk);
314 goto done;
315 }
316
317 if (unlikely(rcvr->sk != sk)) {
318 /* In this case, the association moved from one socket to
319 * another. We are currently sitting on the backlog of the
320 * old socket, so we need to move.
321 * However, since we are here in the process context we
322 * need to take make sure that the user doesn't own
323 * the new socket when we process the packet.
324 * If the new socket is user-owned, queue the chunk to the
325 * backlog of the new socket without dropping any refs.
326 * Otherwise, we can safely push the chunk on the inqueue.
327 */
328
329 sk = rcvr->sk;
330 bh_lock_sock(sk);
331
332 if (sock_owned_by_user(sk)) {
333 if (sk_add_backlog(sk, skb, sk->sk_rcvbuf))
334 sctp_chunk_free(chunk);
335 else
336 backloged = 1;
337 } else
338 sctp_inq_push(inqueue, chunk);
339
340 bh_unlock_sock(sk);
341
342 /* If the chunk was backloged again, don't drop refs */
343 if (backloged)
344 return 0;
345 } else {
346 sctp_inq_push(inqueue, chunk);
347 }
348
349done:
350 /* Release the refs we took in sctp_add_backlog */
351 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
352 sctp_association_put(sctp_assoc(rcvr));
353 else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
354 sctp_endpoint_put(sctp_ep(rcvr));
355 else
356 BUG();
357
358 return 0;
359}
360
361static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb)
362{
363 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
364 struct sctp_ep_common *rcvr = chunk->rcvr;
365 int ret;
366
367 ret = sk_add_backlog(sk, skb, sk->sk_rcvbuf);
368 if (!ret) {
369 /* Hold the assoc/ep while hanging on the backlog queue.
370 * This way, we know structures we need will not disappear
371 * from us
372 */
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));
377 else
378 BUG();
379 }
380 return ret;
381
382}
383
384/* Handle icmp frag needed error. */
385void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc,
386 struct sctp_transport *t, __u32 pmtu)
387{
388 if (!t || (t->pathmtu <= pmtu))
389 return;
390
391 if (sock_owned_by_user(sk)) {
392 asoc->pmtu_pending = 1;
393 t->pmtu_pending = 1;
394 return;
395 }
396
397 if (t->param_flags & SPP_PMTUD_ENABLE) {
398 /* Update transports view of the MTU */
399 sctp_transport_update_pmtu(sk, t, pmtu);
400
401 /* Update association pmtu. */
402 sctp_assoc_sync_pmtu(sk, asoc);
403 }
404
405 /* Retransmit with the new pmtu setting.
406 * Normally, if PMTU discovery is disabled, an ICMP Fragmentation
407 * Needed will never be sent, but if a message was sent before
408 * PMTU discovery was disabled that was larger than the PMTU, it
409 * would not be fragmented, so it must be re-transmitted fragmented.
410 */
411 sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD);
412}
413
414void sctp_icmp_redirect(struct sock *sk, struct sctp_transport *t,
415 struct sk_buff *skb)
416{
417 struct dst_entry *dst;
418
419 if (!t)
420 return;
421 dst = sctp_transport_dst_check(t);
422 if (dst)
423 dst->ops->redirect(dst, sk, skb);
424}
425
426/*
427 * SCTP Implementer's Guide, 2.37 ICMP handling procedures
428 *
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.
432 *
433 * This function sends an event to the state machine, which will abort the
434 * association.
435 *
436 */
437void sctp_icmp_proto_unreachable(struct sock *sk,
438 struct sctp_association *asoc,
439 struct sctp_transport *t)
440{
441 if (sock_owned_by_user(sk)) {
442 if (timer_pending(&t->proto_unreach_timer))
443 return;
444 else {
445 if (!mod_timer(&t->proto_unreach_timer,
446 jiffies + (HZ/20)))
447 sctp_association_hold(asoc);
448 }
449 } else {
450 struct net *net = sock_net(sk);
451
452 pr_debug("%s: unrecognized next header type "
453 "encountered!\n", __func__);
454
455 if (del_timer(&t->proto_unreach_timer))
456 sctp_association_put(asoc);
457
458 sctp_do_sm(net, SCTP_EVENT_T_OTHER,
459 SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH),
460 asoc->state, asoc->ep, asoc, t,
461 GFP_ATOMIC);
462 }
463}
464
465/* Common lookup code for icmp/icmpv6 error handler. */
466struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *skb,
467 struct sctphdr *sctphdr,
468 struct sctp_association **app,
469 struct sctp_transport **tpp)
470{
471 union sctp_addr saddr;
472 union sctp_addr daddr;
473 struct sctp_af *af;
474 struct sock *sk = NULL;
475 struct sctp_association *asoc;
476 struct sctp_transport *transport = NULL;
477 struct sctp_init_chunk *chunkhdr;
478 __u32 vtag = ntohl(sctphdr->vtag);
479 int len = skb->len - ((void *)sctphdr - (void *)skb->data);
480
481 *app = NULL; *tpp = NULL;
482
483 af = sctp_get_af_specific(family);
484 if (unlikely(!af)) {
485 return NULL;
486 }
487
488 /* Initialize local addresses for lookups. */
489 af->from_skb(&saddr, skb, 1);
490 af->from_skb(&daddr, skb, 0);
491
492 /* Look for an association that matches the incoming ICMP error
493 * packet.
494 */
495 asoc = __sctp_lookup_association(net, &saddr, &daddr, &transport);
496 if (!asoc)
497 return NULL;
498
499 sk = asoc->base.sk;
500
501 /* RFC 4960, Appendix C. ICMP Handling
502 *
503 * ICMP6) An implementation MUST validate that the Verification Tag
504 * contained in the ICMP message matches the Verification Tag of
505 * the peer. If the Verification Tag is not 0 and does NOT
506 * match, discard the ICMP message. If it is 0 and the ICMP
507 * message contains enough bytes to verify that the chunk type is
508 * an INIT chunk and that the Initiate Tag matches the tag of the
509 * peer, continue with ICMP7. If the ICMP message is too short
510 * or the chunk type or the Initiate Tag does not match, silently
511 * discard the packet.
512 */
513 if (vtag == 0) {
514 chunkhdr = (void *)sctphdr + sizeof(struct sctphdr);
515 if (len < sizeof(struct sctphdr) + sizeof(sctp_chunkhdr_t)
516 + sizeof(__be32) ||
517 chunkhdr->chunk_hdr.type != SCTP_CID_INIT ||
518 ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag) {
519 goto out;
520 }
521 } else if (vtag != asoc->c.peer_vtag) {
522 goto out;
523 }
524
525 bh_lock_sock(sk);
526
527 /* If too many ICMPs get dropped on busy
528 * servers this needs to be solved differently.
529 */
530 if (sock_owned_by_user(sk))
531 NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
532
533 *app = asoc;
534 *tpp = transport;
535 return sk;
536
537out:
538 sctp_association_put(asoc);
539 return NULL;
540}
541
542/* Common cleanup code for icmp/icmpv6 error handler. */
543void sctp_err_finish(struct sock *sk, struct sctp_association *asoc)
544{
545 bh_unlock_sock(sk);
546 sctp_association_put(asoc);
547}
548
549/*
550 * This routine is called by the ICMP module when it gets some
551 * sort of error condition. If err < 0 then the socket should
552 * be closed and the error returned to the user. If err > 0
553 * it's just the icmp type << 8 | icmp code. After adjustment
554 * header points to the first 8 bytes of the sctp header. We need
555 * to find the appropriate port.
556 *
557 * The locking strategy used here is very "optimistic". When
558 * someone else accesses the socket the ICMP is just dropped
559 * and for some paths there is no check at all.
560 * A more general error queue to queue errors for later handling
561 * is probably better.
562 *
563 */
564void sctp_v4_err(struct sk_buff *skb, __u32 info)
565{
566 const struct iphdr *iph = (const struct iphdr *)skb->data;
567 const int ihlen = iph->ihl * 4;
568 const int type = icmp_hdr(skb)->type;
569 const int code = icmp_hdr(skb)->code;
570 struct sock *sk;
571 struct sctp_association *asoc = NULL;
572 struct sctp_transport *transport;
573 struct inet_sock *inet;
574 __u16 saveip, savesctp;
575 int err;
576 struct net *net = dev_net(skb->dev);
577
578 if (skb->len < ihlen + 8) {
579 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
580 return;
581 }
582
583 /* Fix up skb to look at the embedded net header. */
584 saveip = skb->network_header;
585 savesctp = skb->transport_header;
586 skb_reset_network_header(skb);
587 skb_set_transport_header(skb, ihlen);
588 sk = sctp_err_lookup(net, AF_INET, skb, sctp_hdr(skb), &asoc, &transport);
589 /* Put back, the original values. */
590 skb->network_header = saveip;
591 skb->transport_header = savesctp;
592 if (!sk) {
593 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
594 return;
595 }
596 /* Warning: The sock lock is held. Remember to call
597 * sctp_err_finish!
598 */
599
600 switch (type) {
601 case ICMP_PARAMETERPROB:
602 err = EPROTO;
603 break;
604 case ICMP_DEST_UNREACH:
605 if (code > NR_ICMP_UNREACH)
606 goto out_unlock;
607
608 /* PMTU discovery (RFC1191) */
609 if (ICMP_FRAG_NEEDED == code) {
610 sctp_icmp_frag_needed(sk, asoc, transport, info);
611 goto out_unlock;
612 } else {
613 if (ICMP_PROT_UNREACH == code) {
614 sctp_icmp_proto_unreachable(sk, asoc,
615 transport);
616 goto out_unlock;
617 }
618 }
619 err = icmp_err_convert[code].errno;
620 break;
621 case ICMP_TIME_EXCEEDED:
622 /* Ignore any time exceeded errors due to fragment reassembly
623 * timeouts.
624 */
625 if (ICMP_EXC_FRAGTIME == code)
626 goto out_unlock;
627
628 err = EHOSTUNREACH;
629 break;
630 case ICMP_REDIRECT:
631 sctp_icmp_redirect(sk, transport, skb);
632 /* Fall through to out_unlock. */
633 default:
634 goto out_unlock;
635 }
636
637 inet = inet_sk(sk);
638 if (!sock_owned_by_user(sk) && inet->recverr) {
639 sk->sk_err = err;
640 sk->sk_error_report(sk);
641 } else { /* Only an error on timeout */
642 sk->sk_err_soft = err;
643 }
644
645out_unlock:
646 sctp_err_finish(sk, asoc);
647}
648
649/*
650 * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
651 *
652 * This function scans all the chunks in the OOTB packet to determine if
653 * the packet should be discarded right away. If a response might be needed
654 * for this packet, or, if further processing is possible, the packet will
655 * be queued to a proper inqueue for the next phase of handling.
656 *
657 * Output:
658 * Return 0 - If further processing is needed.
659 * Return 1 - If the packet can be discarded right away.
660 */
661static int sctp_rcv_ootb(struct sk_buff *skb)
662{
663 sctp_chunkhdr_t *ch;
664 __u8 *ch_end;
665
666 ch = (sctp_chunkhdr_t *) skb->data;
667
668 /* Scan through all the chunks in the packet. */
669 do {
670 /* Break out if chunk length is less then minimal. */
671 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
672 break;
673
674 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
675 if (ch_end > skb_tail_pointer(skb))
676 break;
677
678 /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the
679 * receiver MUST silently discard the OOTB packet and take no
680 * further action.
681 */
682 if (SCTP_CID_ABORT == ch->type)
683 goto discard;
684
685 /* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE
686 * chunk, the receiver should silently discard the packet
687 * and take no further action.
688 */
689 if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type)
690 goto discard;
691
692 /* RFC 4460, 2.11.2
693 * This will discard packets with INIT chunk bundled as
694 * subsequent chunks in the packet. When INIT is first,
695 * the normal INIT processing will discard the chunk.
696 */
697 if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data)
698 goto discard;
699
700 ch = (sctp_chunkhdr_t *) ch_end;
701 } while (ch_end < skb_tail_pointer(skb));
702
703 return 0;
704
705discard:
706 return 1;
707}
708
709/* Insert endpoint into the hash table. */
710static void __sctp_hash_endpoint(struct sctp_endpoint *ep)
711{
712 struct net *net = sock_net(ep->base.sk);
713 struct sctp_ep_common *epb;
714 struct sctp_hashbucket *head;
715
716 epb = &ep->base;
717
718 epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port);
719 head = &sctp_ep_hashtable[epb->hashent];
720
721 write_lock(&head->lock);
722 hlist_add_head(&epb->node, &head->chain);
723 write_unlock(&head->lock);
724}
725
726/* Add an endpoint to the hash. Local BH-safe. */
727void sctp_hash_endpoint(struct sctp_endpoint *ep)
728{
729 local_bh_disable();
730 __sctp_hash_endpoint(ep);
731 local_bh_enable();
732}
733
734/* Remove endpoint from the hash table. */
735static void __sctp_unhash_endpoint(struct sctp_endpoint *ep)
736{
737 struct net *net = sock_net(ep->base.sk);
738 struct sctp_hashbucket *head;
739 struct sctp_ep_common *epb;
740
741 epb = &ep->base;
742
743 epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port);
744
745 head = &sctp_ep_hashtable[epb->hashent];
746
747 write_lock(&head->lock);
748 hlist_del_init(&epb->node);
749 write_unlock(&head->lock);
750}
751
752/* Remove endpoint from the hash. Local BH-safe. */
753void sctp_unhash_endpoint(struct sctp_endpoint *ep)
754{
755 local_bh_disable();
756 __sctp_unhash_endpoint(ep);
757 local_bh_enable();
758}
759
760/* Look up an endpoint. */
761static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(struct net *net,
762 const union sctp_addr *laddr)
763{
764 struct sctp_hashbucket *head;
765 struct sctp_ep_common *epb;
766 struct sctp_endpoint *ep;
767 int hash;
768
769 hash = sctp_ep_hashfn(net, ntohs(laddr->v4.sin_port));
770 head = &sctp_ep_hashtable[hash];
771 read_lock(&head->lock);
772 sctp_for_each_hentry(epb, &head->chain) {
773 ep = sctp_ep(epb);
774 if (sctp_endpoint_is_match(ep, net, laddr))
775 goto hit;
776 }
777
778 ep = sctp_sk(net->sctp.ctl_sock)->ep;
779
780hit:
781 sctp_endpoint_hold(ep);
782 read_unlock(&head->lock);
783 return ep;
784}
785
786/* Insert association into the hash table. */
787static void __sctp_hash_established(struct sctp_association *asoc)
788{
789 struct net *net = sock_net(asoc->base.sk);
790 struct sctp_ep_common *epb;
791 struct sctp_hashbucket *head;
792
793 epb = &asoc->base;
794
795 /* Calculate which chain this entry will belong to. */
796 epb->hashent = sctp_assoc_hashfn(net, epb->bind_addr.port,
797 asoc->peer.port);
798
799 head = &sctp_assoc_hashtable[epb->hashent];
800
801 write_lock(&head->lock);
802 hlist_add_head(&epb->node, &head->chain);
803 write_unlock(&head->lock);
804}
805
806/* Add an association to the hash. Local BH-safe. */
807void sctp_hash_established(struct sctp_association *asoc)
808{
809 if (asoc->temp)
810 return;
811
812 local_bh_disable();
813 __sctp_hash_established(asoc);
814 local_bh_enable();
815}
816
817/* Remove association from the hash table. */
818static void __sctp_unhash_established(struct sctp_association *asoc)
819{
820 struct net *net = sock_net(asoc->base.sk);
821 struct sctp_hashbucket *head;
822 struct sctp_ep_common *epb;
823
824 epb = &asoc->base;
825
826 epb->hashent = sctp_assoc_hashfn(net, epb->bind_addr.port,
827 asoc->peer.port);
828
829 head = &sctp_assoc_hashtable[epb->hashent];
830
831 write_lock(&head->lock);
832 hlist_del_init(&epb->node);
833 write_unlock(&head->lock);
834}
835
836/* Remove association from the hash table. Local BH-safe. */
837void sctp_unhash_established(struct sctp_association *asoc)
838{
839 if (asoc->temp)
840 return;
841
842 local_bh_disable();
843 __sctp_unhash_established(asoc);
844 local_bh_enable();
845}
846
847/* Look up an association. */
848static struct sctp_association *__sctp_lookup_association(
849 struct net *net,
850 const union sctp_addr *local,
851 const union sctp_addr *peer,
852 struct sctp_transport **pt)
853{
854 struct sctp_hashbucket *head;
855 struct sctp_ep_common *epb;
856 struct sctp_association *asoc;
857 struct sctp_transport *transport;
858 int hash;
859
860 /* Optimize here for direct hit, only listening connections can
861 * have wildcards anyways.
862 */
863 hash = sctp_assoc_hashfn(net, ntohs(local->v4.sin_port),
864 ntohs(peer->v4.sin_port));
865 head = &sctp_assoc_hashtable[hash];
866 read_lock(&head->lock);
867 sctp_for_each_hentry(epb, &head->chain) {
868 asoc = sctp_assoc(epb);
869 transport = sctp_assoc_is_match(asoc, net, local, peer);
870 if (transport)
871 goto hit;
872 }
873
874 read_unlock(&head->lock);
875
876 return NULL;
877
878hit:
879 *pt = transport;
880 sctp_association_hold(asoc);
881 read_unlock(&head->lock);
882 return asoc;
883}
884
885/* Look up an association. BH-safe. */
886static
887struct sctp_association *sctp_lookup_association(struct net *net,
888 const union sctp_addr *laddr,
889 const union sctp_addr *paddr,
890 struct sctp_transport **transportp)
891{
892 struct sctp_association *asoc;
893
894 local_bh_disable();
895 asoc = __sctp_lookup_association(net, laddr, paddr, transportp);
896 local_bh_enable();
897
898 return asoc;
899}
900
901/* Is there an association matching the given local and peer addresses? */
902int sctp_has_association(struct net *net,
903 const union sctp_addr *laddr,
904 const union sctp_addr *paddr)
905{
906 struct sctp_association *asoc;
907 struct sctp_transport *transport;
908
909 if ((asoc = sctp_lookup_association(net, laddr, paddr, &transport))) {
910 sctp_association_put(asoc);
911 return 1;
912 }
913
914 return 0;
915}
916
917/*
918 * SCTP Implementors Guide, 2.18 Handling of address
919 * parameters within the INIT or INIT-ACK.
920 *
921 * D) When searching for a matching TCB upon reception of an INIT
922 * or INIT-ACK chunk the receiver SHOULD use not only the
923 * source address of the packet (containing the INIT or
924 * INIT-ACK) but the receiver SHOULD also use all valid
925 * address parameters contained within the chunk.
926 *
927 * 2.18.3 Solution description
928 *
929 * This new text clearly specifies to an implementor the need
930 * to look within the INIT or INIT-ACK. Any implementation that
931 * does not do this, may not be able to establish associations
932 * in certain circumstances.
933 *
934 */
935static struct sctp_association *__sctp_rcv_init_lookup(struct net *net,
936 struct sk_buff *skb,
937 const union sctp_addr *laddr, struct sctp_transport **transportp)
938{
939 struct sctp_association *asoc;
940 union sctp_addr addr;
941 union sctp_addr *paddr = &addr;
942 struct sctphdr *sh = sctp_hdr(skb);
943 union sctp_params params;
944 sctp_init_chunk_t *init;
945 struct sctp_transport *transport;
946 struct sctp_af *af;
947
948 /*
949 * This code will NOT touch anything inside the chunk--it is
950 * strictly READ-ONLY.
951 *
952 * RFC 2960 3 SCTP packet Format
953 *
954 * Multiple chunks can be bundled into one SCTP packet up to
955 * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN
956 * COMPLETE chunks. These chunks MUST NOT be bundled with any
957 * other chunk in a packet. See Section 6.10 for more details
958 * on chunk bundling.
959 */
960
961 /* Find the start of the TLVs and the end of the chunk. This is
962 * the region we search for address parameters.
963 */
964 init = (sctp_init_chunk_t *)skb->data;
965
966 /* Walk the parameters looking for embedded addresses. */
967 sctp_walk_params(params, init, init_hdr.params) {
968
969 /* Note: Ignoring hostname addresses. */
970 af = sctp_get_af_specific(param_type2af(params.p->type));
971 if (!af)
972 continue;
973
974 af->from_addr_param(paddr, params.addr, sh->source, 0);
975
976 asoc = __sctp_lookup_association(net, laddr, paddr, &transport);
977 if (asoc)
978 return asoc;
979 }
980
981 return NULL;
982}
983
984/* ADD-IP, Section 5.2
985 * When an endpoint receives an ASCONF Chunk from the remote peer
986 * special procedures may be needed to identify the association the
987 * ASCONF Chunk is associated with. To properly find the association
988 * the following procedures SHOULD be followed:
989 *
990 * D2) If the association is not found, use the address found in the
991 * Address Parameter TLV combined with the port number found in the
992 * SCTP common header. If found proceed to rule D4.
993 *
994 * D2-ext) If more than one ASCONF Chunks are packed together, use the
995 * address found in the ASCONF Address Parameter TLV of each of the
996 * subsequent ASCONF Chunks. If found, proceed to rule D4.
997 */
998static struct sctp_association *__sctp_rcv_asconf_lookup(
999 struct net *net,
1000 sctp_chunkhdr_t *ch,
1001 const union sctp_addr *laddr,
1002 __be16 peer_port,
1003 struct sctp_transport **transportp)
1004{
1005 sctp_addip_chunk_t *asconf = (struct sctp_addip_chunk *)ch;
1006 struct sctp_af *af;
1007 union sctp_addr_param *param;
1008 union sctp_addr paddr;
1009
1010 /* Skip over the ADDIP header and find the Address parameter */
1011 param = (union sctp_addr_param *)(asconf + 1);
1012
1013 af = sctp_get_af_specific(param_type2af(param->p.type));
1014 if (unlikely(!af))
1015 return NULL;
1016
1017 af->from_addr_param(&paddr, param, peer_port, 0);
1018
1019 return __sctp_lookup_association(net, laddr, &paddr, transportp);
1020}
1021
1022
1023/* SCTP-AUTH, Section 6.3:
1024* If the receiver does not find a STCB for a packet containing an AUTH
1025* chunk as the first chunk and not a COOKIE-ECHO chunk as the second
1026* chunk, it MUST use the chunks after the AUTH chunk to look up an existing
1027* association.
1028*
1029* This means that any chunks that can help us identify the association need
1030* to be looked at to find this association.
1031*/
1032static struct sctp_association *__sctp_rcv_walk_lookup(struct net *net,
1033 struct sk_buff *skb,
1034 const union sctp_addr *laddr,
1035 struct sctp_transport **transportp)
1036{
1037 struct sctp_association *asoc = NULL;
1038 sctp_chunkhdr_t *ch;
1039 int have_auth = 0;
1040 unsigned int chunk_num = 1;
1041 __u8 *ch_end;
1042
1043 /* Walk through the chunks looking for AUTH or ASCONF chunks
1044 * to help us find the association.
1045 */
1046 ch = (sctp_chunkhdr_t *) skb->data;
1047 do {
1048 /* Break out if chunk length is less then minimal. */
1049 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
1050 break;
1051
1052 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
1053 if (ch_end > skb_tail_pointer(skb))
1054 break;
1055
1056 switch (ch->type) {
1057 case SCTP_CID_AUTH:
1058 have_auth = chunk_num;
1059 break;
1060
1061 case SCTP_CID_COOKIE_ECHO:
1062 /* If a packet arrives containing an AUTH chunk as
1063 * a first chunk, a COOKIE-ECHO chunk as the second
1064 * chunk, and possibly more chunks after them, and
1065 * the receiver does not have an STCB for that
1066 * packet, then authentication is based on
1067 * the contents of the COOKIE- ECHO chunk.
1068 */
1069 if (have_auth == 1 && chunk_num == 2)
1070 return NULL;
1071 break;
1072
1073 case SCTP_CID_ASCONF:
1074 if (have_auth || net->sctp.addip_noauth)
1075 asoc = __sctp_rcv_asconf_lookup(
1076 net, ch, laddr,
1077 sctp_hdr(skb)->source,
1078 transportp);
1079 default:
1080 break;
1081 }
1082
1083 if (asoc)
1084 break;
1085
1086 ch = (sctp_chunkhdr_t *) ch_end;
1087 chunk_num++;
1088 } while (ch_end < skb_tail_pointer(skb));
1089
1090 return asoc;
1091}
1092
1093/*
1094 * There are circumstances when we need to look inside the SCTP packet
1095 * for information to help us find the association. Examples
1096 * include looking inside of INIT/INIT-ACK chunks or after the AUTH
1097 * chunks.
1098 */
1099static struct sctp_association *__sctp_rcv_lookup_harder(struct net *net,
1100 struct sk_buff *skb,
1101 const union sctp_addr *laddr,
1102 struct sctp_transport **transportp)
1103{
1104 sctp_chunkhdr_t *ch;
1105
1106 ch = (sctp_chunkhdr_t *) skb->data;
1107
1108 /* The code below will attempt to walk the chunk and extract
1109 * parameter information. Before we do that, we need to verify
1110 * that the chunk length doesn't cause overflow. Otherwise, we'll
1111 * walk off the end.
1112 */
1113 if (WORD_ROUND(ntohs(ch->length)) > skb->len)
1114 return NULL;
1115
1116 /* If this is INIT/INIT-ACK look inside the chunk too. */
1117 if (ch->type == SCTP_CID_INIT || ch->type == SCTP_CID_INIT_ACK)
1118 return __sctp_rcv_init_lookup(net, skb, laddr, transportp);
1119
1120 return __sctp_rcv_walk_lookup(net, skb, laddr, transportp);
1121}
1122
1123/* Lookup an association for an inbound skb. */
1124static struct sctp_association *__sctp_rcv_lookup(struct net *net,
1125 struct sk_buff *skb,
1126 const union sctp_addr *paddr,
1127 const union sctp_addr *laddr,
1128 struct sctp_transport **transportp)
1129{
1130 struct sctp_association *asoc;
1131
1132 asoc = __sctp_lookup_association(net, laddr, paddr, transportp);
1133
1134 /* Further lookup for INIT/INIT-ACK packets.
1135 * SCTP Implementors Guide, 2.18 Handling of address
1136 * parameters within the INIT or INIT-ACK.
1137 */
1138 if (!asoc)
1139 asoc = __sctp_rcv_lookup_harder(net, skb, laddr, transportp);
1140
1141 return asoc;
1142}
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
8 *
9 * This file is part of the SCTP kernel implementation
10 *
11 * These functions handle all input from the IP layer into SCTP.
12 *
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)
17 * any later version.
18 *
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.
24 *
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.
29 *
30 * Please send any bug reports or fixes you make to the
31 * email address(es):
32 * lksctp developers <lksctp-developers@lists.sourceforge.net>
33 *
34 * Or submit a bug report through the following website:
35 * http://www.sf.net/projects/lksctp
36 *
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>
46 *
47 * Any bugs reported given to us we will try to fix... any fixes shared will
48 * be incorporated into the next SCTP release.
49 */
50
51#include <linux/types.h>
52#include <linux/list.h> /* For struct list_head */
53#include <linux/socket.h>
54#include <linux/ip.h>
55#include <linux/time.h> /* For struct timeval */
56#include <linux/slab.h>
57#include <net/ip.h>
58#include <net/icmp.h>
59#include <net/snmp.h>
60#include <net/sock.h>
61#include <net/xfrm.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>
66
67/* Forward declarations for internal helpers. */
68static int sctp_rcv_ootb(struct sk_buff *);
69static 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);
73static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr);
74static struct sctp_association *__sctp_lookup_association(
75 const union sctp_addr *local,
76 const union sctp_addr *peer,
77 struct sctp_transport **pt);
78
79static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb);
80
81
82/* Calculate the SCTP checksum of an SCTP packet. */
83static inline int sctp_rcv_checksum(struct sk_buff *skb)
84{
85 struct sctphdr *sh = sctp_hdr(skb);
86 __le32 cmp = sh->checksum;
87 struct sk_buff *list;
88 __le32 val;
89 __u32 tmp = sctp_start_cksum((__u8 *)sh, skb_headlen(skb));
90
91 skb_walk_frags(skb, list)
92 tmp = sctp_update_cksum((__u8 *)list->data, skb_headlen(list),
93 tmp);
94
95 val = sctp_end_cksum(tmp);
96
97 if (val != cmp) {
98 /* CRC failure, dump it. */
99 SCTP_INC_STATS_BH(SCTP_MIB_CHECKSUMERRORS);
100 return -1;
101 }
102 return 0;
103}
104
105struct sctp_input_cb {
106 union {
107 struct inet_skb_parm h4;
108#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
109 struct inet6_skb_parm h6;
110#endif
111 } header;
112 struct sctp_chunk *chunk;
113};
114#define SCTP_INPUT_CB(__skb) ((struct sctp_input_cb *)&((__skb)->cb[0]))
115
116/*
117 * This is the routine which IP calls when receiving an SCTP packet.
118 */
119int sctp_rcv(struct sk_buff *skb)
120{
121 struct sock *sk;
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;
127 struct sctphdr *sh;
128 union sctp_addr src;
129 union sctp_addr dest;
130 int family;
131 struct sctp_af *af;
132
133 if (skb->pkt_type!=PACKET_HOST)
134 goto discard_it;
135
136 SCTP_INC_STATS_BH(SCTP_MIB_INSCTPPACKS);
137
138 if (skb_linearize(skb))
139 goto discard_it;
140
141 sh = sctp_hdr(skb);
142
143 /* Pull up the IP and SCTP headers. */
144 __skb_pull(skb, skb_transport_offset(skb));
145 if (skb->len < sizeof(struct sctphdr))
146 goto discard_it;
147 if (!sctp_checksum_disable && !skb_csum_unnecessary(skb) &&
148 sctp_rcv_checksum(skb) < 0)
149 goto discard_it;
150
151 skb_pull(skb, sizeof(struct sctphdr));
152
153 /* Make sure we at least have chunk headers worth of data left. */
154 if (skb->len < sizeof(struct sctp_chunkhdr))
155 goto discard_it;
156
157 family = ipver2af(ip_hdr(skb)->version);
158 af = sctp_get_af_specific(family);
159 if (unlikely(!af))
160 goto discard_it;
161
162 /* Initialize local addresses for lookups. */
163 af->from_skb(&src, skb, 1);
164 af->from_skb(&dest, skb, 0);
165
166 /* If the packet is to or from a non-unicast address,
167 * silently discard the packet.
168 *
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
175 * address."
176 */
177 if (!af->addr_valid(&src, NULL, skb) ||
178 !af->addr_valid(&dest, NULL, skb))
179 goto discard_it;
180
181 asoc = __sctp_rcv_lookup(skb, &src, &dest, &transport);
182
183 if (!asoc)
184 ep = __sctp_rcv_lookup_endpoint(&dest);
185
186 /* Retrieve the common input handling substructure. */
187 rcvr = asoc ? &asoc->base : &ep->base;
188 sk = rcvr->sk;
189
190 /*
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
193 */
194 if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb)))
195 {
196 if (asoc) {
197 sctp_association_put(asoc);
198 asoc = NULL;
199 } else {
200 sctp_endpoint_put(ep);
201 ep = NULL;
202 }
203 sk = sctp_get_ctl_sock();
204 ep = sctp_sk(sk)->ep;
205 sctp_endpoint_hold(ep);
206 rcvr = &ep->base;
207 }
208
209 /*
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
215 * packet belongs.
216 */
217 if (!asoc) {
218 if (sctp_rcv_ootb(skb)) {
219 SCTP_INC_STATS_BH(SCTP_MIB_OUTOFBLUES);
220 goto discard_release;
221 }
222 }
223
224 if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family))
225 goto discard_release;
226 nf_reset(skb);
227
228 if (sk_filter(sk, skb))
229 goto discard_release;
230
231 /* Create an SCTP packet structure. */
232 chunk = sctp_chunkify(skb, asoc, sk);
233 if (!chunk)
234 goto discard_release;
235 SCTP_INPUT_CB(skb)->chunk = chunk;
236
237 /* Remember what endpoint is to handle this packet. */
238 chunk->rcvr = rcvr;
239
240 /* Remember the SCTP header. */
241 chunk->sctp_hdr = sh;
242
243 /* Set the source and destination addresses of the incoming chunk. */
244 sctp_init_addrs(chunk, &src, &dest);
245
246 /* Remember where we came from. */
247 chunk->transport = transport;
248
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.
252 */
253 sctp_bh_lock_sock(sk);
254
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
261 * of the current sk.
262 */
263 sctp_bh_unlock_sock(sk);
264 sk = rcvr->sk;
265 sctp_bh_lock_sock(sk);
266 }
267
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;
274 }
275 SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_BACKLOG);
276 } else {
277 SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_SOFTIRQ);
278 sctp_inq_push(&chunk->rcvr->inqueue, chunk);
279 }
280
281 sctp_bh_unlock_sock(sk);
282
283 /* Release the asoc/ep ref we took in the lookup calls. */
284 if (asoc)
285 sctp_association_put(asoc);
286 else
287 sctp_endpoint_put(ep);
288
289 return 0;
290
291discard_it:
292 SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_DISCARDS);
293 kfree_skb(skb);
294 return 0;
295
296discard_release:
297 /* Release the asoc/ep ref we took in the lookup calls. */
298 if (asoc)
299 sctp_association_put(asoc);
300 else
301 sctp_endpoint_put(ep);
302
303 goto discard_it;
304}
305
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.
310 */
311int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
312{
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;
316 int backloged = 0;
317
318 rcvr = chunk->rcvr;
319
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.
323 */
324 if (rcvr->dead) {
325 sctp_chunk_free(chunk);
326 goto done;
327 }
328
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.
339 */
340
341 sk = rcvr->sk;
342 sctp_bh_lock_sock(sk);
343
344 if (sock_owned_by_user(sk)) {
345 if (sk_add_backlog(sk, skb))
346 sctp_chunk_free(chunk);
347 else
348 backloged = 1;
349 } else
350 sctp_inq_push(inqueue, chunk);
351
352 sctp_bh_unlock_sock(sk);
353
354 /* If the chunk was backloged again, don't drop refs */
355 if (backloged)
356 return 0;
357 } else {
358 sctp_inq_push(inqueue, chunk);
359 }
360
361done:
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));
367 else
368 BUG();
369
370 return 0;
371}
372
373static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb)
374{
375 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
376 struct sctp_ep_common *rcvr = chunk->rcvr;
377 int ret;
378
379 ret = sk_add_backlog(sk, skb);
380 if (!ret) {
381 /* Hold the assoc/ep while hanging on the backlog queue.
382 * This way, we know structures we need will not disappear
383 * from us
384 */
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));
389 else
390 BUG();
391 }
392 return ret;
393
394}
395
396/* Handle icmp frag needed error. */
397void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc,
398 struct sctp_transport *t, __u32 pmtu)
399{
400 if (!t || (t->pathmtu <= pmtu))
401 return;
402
403 if (sock_owned_by_user(sk)) {
404 asoc->pmtu_pending = 1;
405 t->pmtu_pending = 1;
406 return;
407 }
408
409 if (t->param_flags & SPP_PMTUD_ENABLE) {
410 /* Update transports view of the MTU */
411 sctp_transport_update_pmtu(t, pmtu);
412
413 /* Update association pmtu. */
414 sctp_assoc_sync_pmtu(asoc);
415 }
416
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.
422 */
423 sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD);
424}
425
426/*
427 * SCTP Implementer's Guide, 2.37 ICMP handling procedures
428 *
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.
432 *
433 * This function sends an event to the state machine, which will abort the
434 * association.
435 *
436 */
437void sctp_icmp_proto_unreachable(struct sock *sk,
438 struct sctp_association *asoc,
439 struct sctp_transport *t)
440{
441 SCTP_DEBUG_PRINTK("%s\n", __func__);
442
443 if (sock_owned_by_user(sk)) {
444 if (timer_pending(&t->proto_unreach_timer))
445 return;
446 else {
447 if (!mod_timer(&t->proto_unreach_timer,
448 jiffies + (HZ/20)))
449 sctp_association_hold(asoc);
450 }
451
452 } else {
453 if (timer_pending(&t->proto_unreach_timer) &&
454 del_timer(&t->proto_unreach_timer))
455 sctp_association_put(asoc);
456
457 sctp_do_sm(SCTP_EVENT_T_OTHER,
458 SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH),
459 asoc->state, asoc->ep, asoc, t,
460 GFP_ATOMIC);
461 }
462}
463
464/* Common lookup code for icmp/icmpv6 error handler. */
465struct sock *sctp_err_lookup(int family, struct sk_buff *skb,
466 struct sctphdr *sctphdr,
467 struct sctp_association **app,
468 struct sctp_transport **tpp)
469{
470 union sctp_addr saddr;
471 union sctp_addr daddr;
472 struct sctp_af *af;
473 struct sock *sk = NULL;
474 struct sctp_association *asoc;
475 struct sctp_transport *transport = NULL;
476 struct sctp_init_chunk *chunkhdr;
477 __u32 vtag = ntohl(sctphdr->vtag);
478 int len = skb->len - ((void *)sctphdr - (void *)skb->data);
479
480 *app = NULL; *tpp = NULL;
481
482 af = sctp_get_af_specific(family);
483 if (unlikely(!af)) {
484 return NULL;
485 }
486
487 /* Initialize local addresses for lookups. */
488 af->from_skb(&saddr, skb, 1);
489 af->from_skb(&daddr, skb, 0);
490
491 /* Look for an association that matches the incoming ICMP error
492 * packet.
493 */
494 asoc = __sctp_lookup_association(&saddr, &daddr, &transport);
495 if (!asoc)
496 return NULL;
497
498 sk = asoc->base.sk;
499
500 /* RFC 4960, Appendix C. ICMP Handling
501 *
502 * ICMP6) An implementation MUST validate that the Verification Tag
503 * contained in the ICMP message matches the Verification Tag of
504 * the peer. If the Verification Tag is not 0 and does NOT
505 * match, discard the ICMP message. If it is 0 and the ICMP
506 * message contains enough bytes to verify that the chunk type is
507 * an INIT chunk and that the Initiate Tag matches the tag of the
508 * peer, continue with ICMP7. If the ICMP message is too short
509 * or the chunk type or the Initiate Tag does not match, silently
510 * discard the packet.
511 */
512 if (vtag == 0) {
513 chunkhdr = (void *)sctphdr + sizeof(struct sctphdr);
514 if (len < sizeof(struct sctphdr) + sizeof(sctp_chunkhdr_t)
515 + sizeof(__be32) ||
516 chunkhdr->chunk_hdr.type != SCTP_CID_INIT ||
517 ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag) {
518 goto out;
519 }
520 } else if (vtag != asoc->c.peer_vtag) {
521 goto out;
522 }
523
524 sctp_bh_lock_sock(sk);
525
526 /* If too many ICMPs get dropped on busy
527 * servers this needs to be solved differently.
528 */
529 if (sock_owned_by_user(sk))
530 NET_INC_STATS_BH(&init_net, LINUX_MIB_LOCKDROPPEDICMPS);
531
532 *app = asoc;
533 *tpp = transport;
534 return sk;
535
536out:
537 if (asoc)
538 sctp_association_put(asoc);
539 return NULL;
540}
541
542/* Common cleanup code for icmp/icmpv6 error handler. */
543void sctp_err_finish(struct sock *sk, struct sctp_association *asoc)
544{
545 sctp_bh_unlock_sock(sk);
546 if (asoc)
547 sctp_association_put(asoc);
548}
549
550/*
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.
557 *
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.
563 *
564 */
565void sctp_v4_err(struct sk_buff *skb, __u32 info)
566{
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;
571 struct sock *sk;
572 struct sctp_association *asoc = NULL;
573 struct sctp_transport *transport;
574 struct inet_sock *inet;
575 sk_buff_data_t saveip, savesctp;
576 int err;
577
578 if (skb->len < ihlen + 8) {
579 ICMP_INC_STATS_BH(&init_net, ICMP_MIB_INERRORS);
580 return;
581 }
582
583 /* Fix up skb to look at the embedded net header. */
584 saveip = skb->network_header;
585 savesctp = skb->transport_header;
586 skb_reset_network_header(skb);
587 skb_set_transport_header(skb, ihlen);
588 sk = sctp_err_lookup(AF_INET, skb, sctp_hdr(skb), &asoc, &transport);
589 /* Put back, the original values. */
590 skb->network_header = saveip;
591 skb->transport_header = savesctp;
592 if (!sk) {
593 ICMP_INC_STATS_BH(&init_net, ICMP_MIB_INERRORS);
594 return;
595 }
596 /* Warning: The sock lock is held. Remember to call
597 * sctp_err_finish!
598 */
599
600 switch (type) {
601 case ICMP_PARAMETERPROB:
602 err = EPROTO;
603 break;
604 case ICMP_DEST_UNREACH:
605 if (code > NR_ICMP_UNREACH)
606 goto out_unlock;
607
608 /* PMTU discovery (RFC1191) */
609 if (ICMP_FRAG_NEEDED == code) {
610 sctp_icmp_frag_needed(sk, asoc, transport, info);
611 goto out_unlock;
612 }
613 else {
614 if (ICMP_PROT_UNREACH == code) {
615 sctp_icmp_proto_unreachable(sk, asoc,
616 transport);
617 goto out_unlock;
618 }
619 }
620 err = icmp_err_convert[code].errno;
621 break;
622 case ICMP_TIME_EXCEEDED:
623 /* Ignore any time exceeded errors due to fragment reassembly
624 * timeouts.
625 */
626 if (ICMP_EXC_FRAGTIME == code)
627 goto out_unlock;
628
629 err = EHOSTUNREACH;
630 break;
631 default:
632 goto out_unlock;
633 }
634
635 inet = inet_sk(sk);
636 if (!sock_owned_by_user(sk) && inet->recverr) {
637 sk->sk_err = err;
638 sk->sk_error_report(sk);
639 } else { /* Only an error on timeout */
640 sk->sk_err_soft = err;
641 }
642
643out_unlock:
644 sctp_err_finish(sk, asoc);
645}
646
647/*
648 * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
649 *
650 * This function scans all the chunks in the OOTB packet to determine if
651 * the packet should be discarded right away. If a response might be needed
652 * for this packet, or, if further processing is possible, the packet will
653 * be queued to a proper inqueue for the next phase of handling.
654 *
655 * Output:
656 * Return 0 - If further processing is needed.
657 * Return 1 - If the packet can be discarded right away.
658 */
659static int sctp_rcv_ootb(struct sk_buff *skb)
660{
661 sctp_chunkhdr_t *ch;
662 __u8 *ch_end;
663
664 ch = (sctp_chunkhdr_t *) skb->data;
665
666 /* Scan through all the chunks in the packet. */
667 do {
668 /* Break out if chunk length is less then minimal. */
669 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
670 break;
671
672 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
673 if (ch_end > skb_tail_pointer(skb))
674 break;
675
676 /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the
677 * receiver MUST silently discard the OOTB packet and take no
678 * further action.
679 */
680 if (SCTP_CID_ABORT == ch->type)
681 goto discard;
682
683 /* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE
684 * chunk, the receiver should silently discard the packet
685 * and take no further action.
686 */
687 if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type)
688 goto discard;
689
690 /* RFC 4460, 2.11.2
691 * This will discard packets with INIT chunk bundled as
692 * subsequent chunks in the packet. When INIT is first,
693 * the normal INIT processing will discard the chunk.
694 */
695 if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data)
696 goto discard;
697
698 ch = (sctp_chunkhdr_t *) ch_end;
699 } while (ch_end < skb_tail_pointer(skb));
700
701 return 0;
702
703discard:
704 return 1;
705}
706
707/* Insert endpoint into the hash table. */
708static void __sctp_hash_endpoint(struct sctp_endpoint *ep)
709{
710 struct sctp_ep_common *epb;
711 struct sctp_hashbucket *head;
712
713 epb = &ep->base;
714
715 epb->hashent = sctp_ep_hashfn(epb->bind_addr.port);
716 head = &sctp_ep_hashtable[epb->hashent];
717
718 sctp_write_lock(&head->lock);
719 hlist_add_head(&epb->node, &head->chain);
720 sctp_write_unlock(&head->lock);
721}
722
723/* Add an endpoint to the hash. Local BH-safe. */
724void sctp_hash_endpoint(struct sctp_endpoint *ep)
725{
726 sctp_local_bh_disable();
727 __sctp_hash_endpoint(ep);
728 sctp_local_bh_enable();
729}
730
731/* Remove endpoint from the hash table. */
732static void __sctp_unhash_endpoint(struct sctp_endpoint *ep)
733{
734 struct sctp_hashbucket *head;
735 struct sctp_ep_common *epb;
736
737 epb = &ep->base;
738
739 if (hlist_unhashed(&epb->node))
740 return;
741
742 epb->hashent = sctp_ep_hashfn(epb->bind_addr.port);
743
744 head = &sctp_ep_hashtable[epb->hashent];
745
746 sctp_write_lock(&head->lock);
747 __hlist_del(&epb->node);
748 sctp_write_unlock(&head->lock);
749}
750
751/* Remove endpoint from the hash. Local BH-safe. */
752void sctp_unhash_endpoint(struct sctp_endpoint *ep)
753{
754 sctp_local_bh_disable();
755 __sctp_unhash_endpoint(ep);
756 sctp_local_bh_enable();
757}
758
759/* Look up an endpoint. */
760static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr)
761{
762 struct sctp_hashbucket *head;
763 struct sctp_ep_common *epb;
764 struct sctp_endpoint *ep;
765 struct hlist_node *node;
766 int hash;
767
768 hash = sctp_ep_hashfn(ntohs(laddr->v4.sin_port));
769 head = &sctp_ep_hashtable[hash];
770 read_lock(&head->lock);
771 sctp_for_each_hentry(epb, node, &head->chain) {
772 ep = sctp_ep(epb);
773 if (sctp_endpoint_is_match(ep, laddr))
774 goto hit;
775 }
776
777 ep = sctp_sk((sctp_get_ctl_sock()))->ep;
778
779hit:
780 sctp_endpoint_hold(ep);
781 read_unlock(&head->lock);
782 return ep;
783}
784
785/* Insert association into the hash table. */
786static void __sctp_hash_established(struct sctp_association *asoc)
787{
788 struct sctp_ep_common *epb;
789 struct sctp_hashbucket *head;
790
791 epb = &asoc->base;
792
793 /* Calculate which chain this entry will belong to. */
794 epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port, asoc->peer.port);
795
796 head = &sctp_assoc_hashtable[epb->hashent];
797
798 sctp_write_lock(&head->lock);
799 hlist_add_head(&epb->node, &head->chain);
800 sctp_write_unlock(&head->lock);
801}
802
803/* Add an association to the hash. Local BH-safe. */
804void sctp_hash_established(struct sctp_association *asoc)
805{
806 if (asoc->temp)
807 return;
808
809 sctp_local_bh_disable();
810 __sctp_hash_established(asoc);
811 sctp_local_bh_enable();
812}
813
814/* Remove association from the hash table. */
815static void __sctp_unhash_established(struct sctp_association *asoc)
816{
817 struct sctp_hashbucket *head;
818 struct sctp_ep_common *epb;
819
820 epb = &asoc->base;
821
822 epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port,
823 asoc->peer.port);
824
825 head = &sctp_assoc_hashtable[epb->hashent];
826
827 sctp_write_lock(&head->lock);
828 __hlist_del(&epb->node);
829 sctp_write_unlock(&head->lock);
830}
831
832/* Remove association from the hash table. Local BH-safe. */
833void sctp_unhash_established(struct sctp_association *asoc)
834{
835 if (asoc->temp)
836 return;
837
838 sctp_local_bh_disable();
839 __sctp_unhash_established(asoc);
840 sctp_local_bh_enable();
841}
842
843/* Look up an association. */
844static struct sctp_association *__sctp_lookup_association(
845 const union sctp_addr *local,
846 const union sctp_addr *peer,
847 struct sctp_transport **pt)
848{
849 struct sctp_hashbucket *head;
850 struct sctp_ep_common *epb;
851 struct sctp_association *asoc;
852 struct sctp_transport *transport;
853 struct hlist_node *node;
854 int hash;
855
856 /* Optimize here for direct hit, only listening connections can
857 * have wildcards anyways.
858 */
859 hash = sctp_assoc_hashfn(ntohs(local->v4.sin_port), ntohs(peer->v4.sin_port));
860 head = &sctp_assoc_hashtable[hash];
861 read_lock(&head->lock);
862 sctp_for_each_hentry(epb, node, &head->chain) {
863 asoc = sctp_assoc(epb);
864 transport = sctp_assoc_is_match(asoc, local, peer);
865 if (transport)
866 goto hit;
867 }
868
869 read_unlock(&head->lock);
870
871 return NULL;
872
873hit:
874 *pt = transport;
875 sctp_association_hold(asoc);
876 read_unlock(&head->lock);
877 return asoc;
878}
879
880/* Look up an association. BH-safe. */
881SCTP_STATIC
882struct sctp_association *sctp_lookup_association(const union sctp_addr *laddr,
883 const union sctp_addr *paddr,
884 struct sctp_transport **transportp)
885{
886 struct sctp_association *asoc;
887
888 sctp_local_bh_disable();
889 asoc = __sctp_lookup_association(laddr, paddr, transportp);
890 sctp_local_bh_enable();
891
892 return asoc;
893}
894
895/* Is there an association matching the given local and peer addresses? */
896int sctp_has_association(const union sctp_addr *laddr,
897 const union sctp_addr *paddr)
898{
899 struct sctp_association *asoc;
900 struct sctp_transport *transport;
901
902 if ((asoc = sctp_lookup_association(laddr, paddr, &transport))) {
903 sctp_association_put(asoc);
904 return 1;
905 }
906
907 return 0;
908}
909
910/*
911 * SCTP Implementors Guide, 2.18 Handling of address
912 * parameters within the INIT or INIT-ACK.
913 *
914 * D) When searching for a matching TCB upon reception of an INIT
915 * or INIT-ACK chunk the receiver SHOULD use not only the
916 * source address of the packet (containing the INIT or
917 * INIT-ACK) but the receiver SHOULD also use all valid
918 * address parameters contained within the chunk.
919 *
920 * 2.18.3 Solution description
921 *
922 * This new text clearly specifies to an implementor the need
923 * to look within the INIT or INIT-ACK. Any implementation that
924 * does not do this, may not be able to establish associations
925 * in certain circumstances.
926 *
927 */
928static struct sctp_association *__sctp_rcv_init_lookup(struct sk_buff *skb,
929 const union sctp_addr *laddr, struct sctp_transport **transportp)
930{
931 struct sctp_association *asoc;
932 union sctp_addr addr;
933 union sctp_addr *paddr = &addr;
934 struct sctphdr *sh = sctp_hdr(skb);
935 union sctp_params params;
936 sctp_init_chunk_t *init;
937 struct sctp_transport *transport;
938 struct sctp_af *af;
939
940 /*
941 * This code will NOT touch anything inside the chunk--it is
942 * strictly READ-ONLY.
943 *
944 * RFC 2960 3 SCTP packet Format
945 *
946 * Multiple chunks can be bundled into one SCTP packet up to
947 * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN
948 * COMPLETE chunks. These chunks MUST NOT be bundled with any
949 * other chunk in a packet. See Section 6.10 for more details
950 * on chunk bundling.
951 */
952
953 /* Find the start of the TLVs and the end of the chunk. This is
954 * the region we search for address parameters.
955 */
956 init = (sctp_init_chunk_t *)skb->data;
957
958 /* Walk the parameters looking for embedded addresses. */
959 sctp_walk_params(params, init, init_hdr.params) {
960
961 /* Note: Ignoring hostname addresses. */
962 af = sctp_get_af_specific(param_type2af(params.p->type));
963 if (!af)
964 continue;
965
966 af->from_addr_param(paddr, params.addr, sh->source, 0);
967
968 asoc = __sctp_lookup_association(laddr, paddr, &transport);
969 if (asoc)
970 return asoc;
971 }
972
973 return NULL;
974}
975
976/* ADD-IP, Section 5.2
977 * When an endpoint receives an ASCONF Chunk from the remote peer
978 * special procedures may be needed to identify the association the
979 * ASCONF Chunk is associated with. To properly find the association
980 * the following procedures SHOULD be followed:
981 *
982 * D2) If the association is not found, use the address found in the
983 * Address Parameter TLV combined with the port number found in the
984 * SCTP common header. If found proceed to rule D4.
985 *
986 * D2-ext) If more than one ASCONF Chunks are packed together, use the
987 * address found in the ASCONF Address Parameter TLV of each of the
988 * subsequent ASCONF Chunks. If found, proceed to rule D4.
989 */
990static struct sctp_association *__sctp_rcv_asconf_lookup(
991 sctp_chunkhdr_t *ch,
992 const union sctp_addr *laddr,
993 __be16 peer_port,
994 struct sctp_transport **transportp)
995{
996 sctp_addip_chunk_t *asconf = (struct sctp_addip_chunk *)ch;
997 struct sctp_af *af;
998 union sctp_addr_param *param;
999 union sctp_addr paddr;
1000
1001 /* Skip over the ADDIP header and find the Address parameter */
1002 param = (union sctp_addr_param *)(asconf + 1);
1003
1004 af = sctp_get_af_specific(param_type2af(param->p.type));
1005 if (unlikely(!af))
1006 return NULL;
1007
1008 af->from_addr_param(&paddr, param, peer_port, 0);
1009
1010 return __sctp_lookup_association(laddr, &paddr, transportp);
1011}
1012
1013
1014/* SCTP-AUTH, Section 6.3:
1015* If the receiver does not find a STCB for a packet containing an AUTH
1016* chunk as the first chunk and not a COOKIE-ECHO chunk as the second
1017* chunk, it MUST use the chunks after the AUTH chunk to look up an existing
1018* association.
1019*
1020* This means that any chunks that can help us identify the association need
1021* to be looked at to find this association.
1022*/
1023static struct sctp_association *__sctp_rcv_walk_lookup(struct sk_buff *skb,
1024 const union sctp_addr *laddr,
1025 struct sctp_transport **transportp)
1026{
1027 struct sctp_association *asoc = NULL;
1028 sctp_chunkhdr_t *ch;
1029 int have_auth = 0;
1030 unsigned int chunk_num = 1;
1031 __u8 *ch_end;
1032
1033 /* Walk through the chunks looking for AUTH or ASCONF chunks
1034 * to help us find the association.
1035 */
1036 ch = (sctp_chunkhdr_t *) skb->data;
1037 do {
1038 /* Break out if chunk length is less then minimal. */
1039 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
1040 break;
1041
1042 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
1043 if (ch_end > skb_tail_pointer(skb))
1044 break;
1045
1046 switch(ch->type) {
1047 case SCTP_CID_AUTH:
1048 have_auth = chunk_num;
1049 break;
1050
1051 case SCTP_CID_COOKIE_ECHO:
1052 /* If a packet arrives containing an AUTH chunk as
1053 * a first chunk, a COOKIE-ECHO chunk as the second
1054 * chunk, and possibly more chunks after them, and
1055 * the receiver does not have an STCB for that
1056 * packet, then authentication is based on
1057 * the contents of the COOKIE- ECHO chunk.
1058 */
1059 if (have_auth == 1 && chunk_num == 2)
1060 return NULL;
1061 break;
1062
1063 case SCTP_CID_ASCONF:
1064 if (have_auth || sctp_addip_noauth)
1065 asoc = __sctp_rcv_asconf_lookup(ch, laddr,
1066 sctp_hdr(skb)->source,
1067 transportp);
1068 default:
1069 break;
1070 }
1071
1072 if (asoc)
1073 break;
1074
1075 ch = (sctp_chunkhdr_t *) ch_end;
1076 chunk_num++;
1077 } while (ch_end < skb_tail_pointer(skb));
1078
1079 return asoc;
1080}
1081
1082/*
1083 * There are circumstances when we need to look inside the SCTP packet
1084 * for information to help us find the association. Examples
1085 * include looking inside of INIT/INIT-ACK chunks or after the AUTH
1086 * chunks.
1087 */
1088static struct sctp_association *__sctp_rcv_lookup_harder(struct sk_buff *skb,
1089 const union sctp_addr *laddr,
1090 struct sctp_transport **transportp)
1091{
1092 sctp_chunkhdr_t *ch;
1093
1094 ch = (sctp_chunkhdr_t *) skb->data;
1095
1096 /* The code below will attempt to walk the chunk and extract
1097 * parameter information. Before we do that, we need to verify
1098 * that the chunk length doesn't cause overflow. Otherwise, we'll
1099 * walk off the end.
1100 */
1101 if (WORD_ROUND(ntohs(ch->length)) > skb->len)
1102 return NULL;
1103
1104 /* If this is INIT/INIT-ACK look inside the chunk too. */
1105 switch (ch->type) {
1106 case SCTP_CID_INIT:
1107 case SCTP_CID_INIT_ACK:
1108 return __sctp_rcv_init_lookup(skb, laddr, transportp);
1109 break;
1110
1111 default:
1112 return __sctp_rcv_walk_lookup(skb, laddr, transportp);
1113 break;
1114 }
1115
1116
1117 return NULL;
1118}
1119
1120/* Lookup an association for an inbound skb. */
1121static struct sctp_association *__sctp_rcv_lookup(struct sk_buff *skb,
1122 const union sctp_addr *paddr,
1123 const union sctp_addr *laddr,
1124 struct sctp_transport **transportp)
1125{
1126 struct sctp_association *asoc;
1127
1128 asoc = __sctp_lookup_association(laddr, paddr, transportp);
1129
1130 /* Further lookup for INIT/INIT-ACK packets.
1131 * SCTP Implementors Guide, 2.18 Handling of address
1132 * parameters within the INIT or INIT-ACK.
1133 */
1134 if (!asoc)
1135 asoc = __sctp_rcv_lookup_harder(skb, laddr, transportp);
1136
1137 return asoc;
1138}