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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
137 skb->csum_valid = 0; /* Previous value not applicable */
138 if (skb_csum_unnecessary(skb))
139 __skb_decr_checksum_unnecessary(skb);
140 else if (!sctp_checksum_disable && sctp_rcv_checksum(net, skb) < 0)
141 goto discard_it;
142 skb->csum_valid = 1;
143
144 skb_pull(skb, sizeof(struct sctphdr));
145
146 /* Make sure we at least have chunk headers worth of data left. */
147 if (skb->len < sizeof(struct sctp_chunkhdr))
148 goto discard_it;
149
150 family = ipver2af(ip_hdr(skb)->version);
151 af = sctp_get_af_specific(family);
152 if (unlikely(!af))
153 goto discard_it;
154
155 /* Initialize local addresses for lookups. */
156 af->from_skb(&src, skb, 1);
157 af->from_skb(&dest, skb, 0);
158
159 /* If the packet is to or from a non-unicast address,
160 * silently discard the packet.
161 *
162 * This is not clearly defined in the RFC except in section
163 * 8.4 - OOTB handling. However, based on the book "Stream Control
164 * Transmission Protocol" 2.1, "It is important to note that the
165 * IP address of an SCTP transport address must be a routable
166 * unicast address. In other words, IP multicast addresses and
167 * IP broadcast addresses cannot be used in an SCTP transport
168 * address."
169 */
170 if (!af->addr_valid(&src, NULL, skb) ||
171 !af->addr_valid(&dest, NULL, skb))
172 goto discard_it;
173
174 asoc = __sctp_rcv_lookup(net, skb, &src, &dest, &transport);
175
176 if (!asoc)
177 ep = __sctp_rcv_lookup_endpoint(net, &dest);
178
179 /* Retrieve the common input handling substructure. */
180 rcvr = asoc ? &asoc->base : &ep->base;
181 sk = rcvr->sk;
182
183 /*
184 * If a frame arrives on an interface and the receiving socket is
185 * bound to another interface, via SO_BINDTODEVICE, treat it as OOTB
186 */
187 if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb))) {
188 if (asoc) {
189 sctp_association_put(asoc);
190 asoc = NULL;
191 } else {
192 sctp_endpoint_put(ep);
193 ep = NULL;
194 }
195 sk = net->sctp.ctl_sock;
196 ep = sctp_sk(sk)->ep;
197 sctp_endpoint_hold(ep);
198 rcvr = &ep->base;
199 }
200
201 /*
202 * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
203 * An SCTP packet is called an "out of the blue" (OOTB)
204 * packet if it is correctly formed, i.e., passed the
205 * receiver's checksum check, but the receiver is not
206 * able to identify the association to which this
207 * packet belongs.
208 */
209 if (!asoc) {
210 if (sctp_rcv_ootb(skb)) {
211 SCTP_INC_STATS_BH(net, SCTP_MIB_OUTOFBLUES);
212 goto discard_release;
213 }
214 }
215
216 if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family))
217 goto discard_release;
218 nf_reset(skb);
219
220 if (sk_filter(sk, skb))
221 goto discard_release;
222
223 /* Create an SCTP packet structure. */
224 chunk = sctp_chunkify(skb, asoc, sk, GFP_ATOMIC);
225 if (!chunk)
226 goto discard_release;
227 SCTP_INPUT_CB(skb)->chunk = chunk;
228
229 /* Remember what endpoint is to handle this packet. */
230 chunk->rcvr = rcvr;
231
232 /* Remember the SCTP header. */
233 chunk->sctp_hdr = sh;
234
235 /* Set the source and destination addresses of the incoming chunk. */
236 sctp_init_addrs(chunk, &src, &dest);
237
238 /* Remember where we came from. */
239 chunk->transport = transport;
240
241 /* Acquire access to the sock lock. Note: We are safe from other
242 * bottom halves on this lock, but a user may be in the lock too,
243 * so check if it is busy.
244 */
245 bh_lock_sock(sk);
246
247 if (sk != rcvr->sk) {
248 /* Our cached sk is different from the rcvr->sk. This is
249 * because migrate()/accept() may have moved the association
250 * to a new socket and released all the sockets. So now we
251 * are holding a lock on the old socket while the user may
252 * be doing something with the new socket. Switch our veiw
253 * of the current sk.
254 */
255 bh_unlock_sock(sk);
256 sk = rcvr->sk;
257 bh_lock_sock(sk);
258 }
259
260 if (sock_owned_by_user(sk)) {
261 if (sctp_add_backlog(sk, skb)) {
262 bh_unlock_sock(sk);
263 sctp_chunk_free(chunk);
264 skb = NULL; /* sctp_chunk_free already freed the skb */
265 goto discard_release;
266 }
267 SCTP_INC_STATS_BH(net, SCTP_MIB_IN_PKT_BACKLOG);
268 } else {
269 SCTP_INC_STATS_BH(net, SCTP_MIB_IN_PKT_SOFTIRQ);
270 sctp_inq_push(&chunk->rcvr->inqueue, chunk);
271 }
272
273 bh_unlock_sock(sk);
274
275 /* Release the asoc/ep ref we took in the lookup calls. */
276 if (asoc)
277 sctp_association_put(asoc);
278 else
279 sctp_endpoint_put(ep);
280
281 return 0;
282
283discard_it:
284 SCTP_INC_STATS_BH(net, SCTP_MIB_IN_PKT_DISCARDS);
285 kfree_skb(skb);
286 return 0;
287
288discard_release:
289 /* Release the asoc/ep ref we took in the lookup calls. */
290 if (asoc)
291 sctp_association_put(asoc);
292 else
293 sctp_endpoint_put(ep);
294
295 goto discard_it;
296}
297
298/* Process the backlog queue of the socket. Every skb on
299 * the backlog holds a ref on an association or endpoint.
300 * We hold this ref throughout the state machine to make
301 * sure that the structure we need is still around.
302 */
303int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
304{
305 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
306 struct sctp_inq *inqueue = &chunk->rcvr->inqueue;
307 struct sctp_ep_common *rcvr = NULL;
308 int backloged = 0;
309
310 rcvr = chunk->rcvr;
311
312 /* If the rcvr is dead then the association or endpoint
313 * has been deleted and we can safely drop the chunk
314 * and refs that we are holding.
315 */
316 if (rcvr->dead) {
317 sctp_chunk_free(chunk);
318 goto done;
319 }
320
321 if (unlikely(rcvr->sk != sk)) {
322 /* In this case, the association moved from one socket to
323 * another. We are currently sitting on the backlog of the
324 * old socket, so we need to move.
325 * However, since we are here in the process context we
326 * need to take make sure that the user doesn't own
327 * the new socket when we process the packet.
328 * If the new socket is user-owned, queue the chunk to the
329 * backlog of the new socket without dropping any refs.
330 * Otherwise, we can safely push the chunk on the inqueue.
331 */
332
333 sk = rcvr->sk;
334 bh_lock_sock(sk);
335
336 if (sock_owned_by_user(sk)) {
337 if (sk_add_backlog(sk, skb, sk->sk_rcvbuf))
338 sctp_chunk_free(chunk);
339 else
340 backloged = 1;
341 } else
342 sctp_inq_push(inqueue, chunk);
343
344 bh_unlock_sock(sk);
345
346 /* If the chunk was backloged again, don't drop refs */
347 if (backloged)
348 return 0;
349 } else {
350 sctp_inq_push(inqueue, chunk);
351 }
352
353done:
354 /* Release the refs we took in sctp_add_backlog */
355 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
356 sctp_association_put(sctp_assoc(rcvr));
357 else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
358 sctp_endpoint_put(sctp_ep(rcvr));
359 else
360 BUG();
361
362 return 0;
363}
364
365static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb)
366{
367 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
368 struct sctp_ep_common *rcvr = chunk->rcvr;
369 int ret;
370
371 ret = sk_add_backlog(sk, skb, sk->sk_rcvbuf);
372 if (!ret) {
373 /* Hold the assoc/ep while hanging on the backlog queue.
374 * This way, we know structures we need will not disappear
375 * from us
376 */
377 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
378 sctp_association_hold(sctp_assoc(rcvr));
379 else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
380 sctp_endpoint_hold(sctp_ep(rcvr));
381 else
382 BUG();
383 }
384 return ret;
385
386}
387
388/* Handle icmp frag needed error. */
389void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc,
390 struct sctp_transport *t, __u32 pmtu)
391{
392 if (!t || (t->pathmtu <= pmtu))
393 return;
394
395 if (sock_owned_by_user(sk)) {
396 asoc->pmtu_pending = 1;
397 t->pmtu_pending = 1;
398 return;
399 }
400
401 if (t->param_flags & SPP_PMTUD_ENABLE) {
402 /* Update transports view of the MTU */
403 sctp_transport_update_pmtu(sk, t, pmtu);
404
405 /* Update association pmtu. */
406 sctp_assoc_sync_pmtu(sk, asoc);
407 }
408
409 /* Retransmit with the new pmtu setting.
410 * Normally, if PMTU discovery is disabled, an ICMP Fragmentation
411 * Needed will never be sent, but if a message was sent before
412 * PMTU discovery was disabled that was larger than the PMTU, it
413 * would not be fragmented, so it must be re-transmitted fragmented.
414 */
415 sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD);
416}
417
418void sctp_icmp_redirect(struct sock *sk, struct sctp_transport *t,
419 struct sk_buff *skb)
420{
421 struct dst_entry *dst;
422
423 if (!t)
424 return;
425 dst = sctp_transport_dst_check(t);
426 if (dst)
427 dst->ops->redirect(dst, sk, skb);
428}
429
430/*
431 * SCTP Implementer's Guide, 2.37 ICMP handling procedures
432 *
433 * ICMP8) If the ICMP code is a "Unrecognized next header type encountered"
434 * or a "Protocol Unreachable" treat this message as an abort
435 * with the T bit set.
436 *
437 * This function sends an event to the state machine, which will abort the
438 * association.
439 *
440 */
441void sctp_icmp_proto_unreachable(struct sock *sk,
442 struct sctp_association *asoc,
443 struct sctp_transport *t)
444{
445 if (sock_owned_by_user(sk)) {
446 if (timer_pending(&t->proto_unreach_timer))
447 return;
448 else {
449 if (!mod_timer(&t->proto_unreach_timer,
450 jiffies + (HZ/20)))
451 sctp_association_hold(asoc);
452 }
453 } else {
454 struct net *net = sock_net(sk);
455
456 pr_debug("%s: unrecognized next header type "
457 "encountered!\n", __func__);
458
459 if (del_timer(&t->proto_unreach_timer))
460 sctp_association_put(asoc);
461
462 sctp_do_sm(net, SCTP_EVENT_T_OTHER,
463 SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH),
464 asoc->state, asoc->ep, asoc, t,
465 GFP_ATOMIC);
466 }
467}
468
469/* Common lookup code for icmp/icmpv6 error handler. */
470struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *skb,
471 struct sctphdr *sctphdr,
472 struct sctp_association **app,
473 struct sctp_transport **tpp)
474{
475 union sctp_addr saddr;
476 union sctp_addr daddr;
477 struct sctp_af *af;
478 struct sock *sk = NULL;
479 struct sctp_association *asoc;
480 struct sctp_transport *transport = NULL;
481 struct sctp_init_chunk *chunkhdr;
482 __u32 vtag = ntohl(sctphdr->vtag);
483 int len = skb->len - ((void *)sctphdr - (void *)skb->data);
484
485 *app = NULL; *tpp = NULL;
486
487 af = sctp_get_af_specific(family);
488 if (unlikely(!af)) {
489 return NULL;
490 }
491
492 /* Initialize local addresses for lookups. */
493 af->from_skb(&saddr, skb, 1);
494 af->from_skb(&daddr, skb, 0);
495
496 /* Look for an association that matches the incoming ICMP error
497 * packet.
498 */
499 asoc = __sctp_lookup_association(net, &saddr, &daddr, &transport);
500 if (!asoc)
501 return NULL;
502
503 sk = asoc->base.sk;
504
505 /* RFC 4960, Appendix C. ICMP Handling
506 *
507 * ICMP6) An implementation MUST validate that the Verification Tag
508 * contained in the ICMP message matches the Verification Tag of
509 * the peer. If the Verification Tag is not 0 and does NOT
510 * match, discard the ICMP message. If it is 0 and the ICMP
511 * message contains enough bytes to verify that the chunk type is
512 * an INIT chunk and that the Initiate Tag matches the tag of the
513 * peer, continue with ICMP7. If the ICMP message is too short
514 * or the chunk type or the Initiate Tag does not match, silently
515 * discard the packet.
516 */
517 if (vtag == 0) {
518 chunkhdr = (void *)sctphdr + sizeof(struct sctphdr);
519 if (len < sizeof(struct sctphdr) + sizeof(sctp_chunkhdr_t)
520 + sizeof(__be32) ||
521 chunkhdr->chunk_hdr.type != SCTP_CID_INIT ||
522 ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag) {
523 goto out;
524 }
525 } else if (vtag != asoc->c.peer_vtag) {
526 goto out;
527 }
528
529 bh_lock_sock(sk);
530
531 /* If too many ICMPs get dropped on busy
532 * servers this needs to be solved differently.
533 */
534 if (sock_owned_by_user(sk))
535 NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
536
537 *app = asoc;
538 *tpp = transport;
539 return sk;
540
541out:
542 sctp_association_put(asoc);
543 return NULL;
544}
545
546/* Common cleanup code for icmp/icmpv6 error handler. */
547void sctp_err_finish(struct sock *sk, struct sctp_association *asoc)
548{
549 bh_unlock_sock(sk);
550 sctp_association_put(asoc);
551}
552
553/*
554 * This routine is called by the ICMP module when it gets some
555 * sort of error condition. If err < 0 then the socket should
556 * be closed and the error returned to the user. If err > 0
557 * it's just the icmp type << 8 | icmp code. After adjustment
558 * header points to the first 8 bytes of the sctp header. We need
559 * to find the appropriate port.
560 *
561 * The locking strategy used here is very "optimistic". When
562 * someone else accesses the socket the ICMP is just dropped
563 * and for some paths there is no check at all.
564 * A more general error queue to queue errors for later handling
565 * is probably better.
566 *
567 */
568void sctp_v4_err(struct sk_buff *skb, __u32 info)
569{
570 const struct iphdr *iph = (const struct iphdr *)skb->data;
571 const int ihlen = iph->ihl * 4;
572 const int type = icmp_hdr(skb)->type;
573 const int code = icmp_hdr(skb)->code;
574 struct sock *sk;
575 struct sctp_association *asoc = NULL;
576 struct sctp_transport *transport;
577 struct inet_sock *inet;
578 __u16 saveip, savesctp;
579 int err;
580 struct net *net = dev_net(skb->dev);
581
582 /* Fix up skb to look at the embedded net header. */
583 saveip = skb->network_header;
584 savesctp = skb->transport_header;
585 skb_reset_network_header(skb);
586 skb_set_transport_header(skb, ihlen);
587 sk = sctp_err_lookup(net, AF_INET, skb, sctp_hdr(skb), &asoc, &transport);
588 /* Put back, the original values. */
589 skb->network_header = saveip;
590 skb->transport_header = savesctp;
591 if (!sk) {
592 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
593 return;
594 }
595 /* Warning: The sock lock is held. Remember to call
596 * sctp_err_finish!
597 */
598
599 switch (type) {
600 case ICMP_PARAMETERPROB:
601 err = EPROTO;
602 break;
603 case ICMP_DEST_UNREACH:
604 if (code > NR_ICMP_UNREACH)
605 goto out_unlock;
606
607 /* PMTU discovery (RFC1191) */
608 if (ICMP_FRAG_NEEDED == code) {
609 sctp_icmp_frag_needed(sk, asoc, transport,
610 WORD_TRUNC(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/* rhashtable for transport */
787struct sctp_hash_cmp_arg {
788 const struct sctp_endpoint *ep;
789 const union sctp_addr *laddr;
790 const union sctp_addr *paddr;
791 const struct net *net;
792};
793
794static inline int sctp_hash_cmp(struct rhashtable_compare_arg *arg,
795 const void *ptr)
796{
797 const struct sctp_hash_cmp_arg *x = arg->key;
798 const struct sctp_transport *t = ptr;
799 struct sctp_association *asoc = t->asoc;
800 const struct net *net = x->net;
801
802 if (!sctp_cmp_addr_exact(&t->ipaddr, x->paddr))
803 return 1;
804 if (!net_eq(sock_net(asoc->base.sk), net))
805 return 1;
806 if (x->ep) {
807 if (x->ep != asoc->ep)
808 return 1;
809 } else {
810 if (x->laddr->v4.sin_port != htons(asoc->base.bind_addr.port))
811 return 1;
812 if (!sctp_bind_addr_match(&asoc->base.bind_addr,
813 x->laddr, sctp_sk(asoc->base.sk)))
814 return 1;
815 }
816
817 return 0;
818}
819
820static inline u32 sctp_hash_obj(const void *data, u32 len, u32 seed)
821{
822 const struct sctp_transport *t = data;
823 const union sctp_addr *paddr = &t->ipaddr;
824 const struct net *net = sock_net(t->asoc->base.sk);
825 u16 lport = htons(t->asoc->base.bind_addr.port);
826 u32 addr;
827
828 if (paddr->sa.sa_family == AF_INET6)
829 addr = jhash(&paddr->v6.sin6_addr, 16, seed);
830 else
831 addr = paddr->v4.sin_addr.s_addr;
832
833 return jhash_3words(addr, ((__u32)paddr->v4.sin_port) << 16 |
834 (__force __u32)lport, net_hash_mix(net), seed);
835}
836
837static inline u32 sctp_hash_key(const void *data, u32 len, u32 seed)
838{
839 const struct sctp_hash_cmp_arg *x = data;
840 const union sctp_addr *paddr = x->paddr;
841 const struct net *net = x->net;
842 u16 lport;
843 u32 addr;
844
845 lport = x->ep ? htons(x->ep->base.bind_addr.port) :
846 x->laddr->v4.sin_port;
847 if (paddr->sa.sa_family == AF_INET6)
848 addr = jhash(&paddr->v6.sin6_addr, 16, seed);
849 else
850 addr = paddr->v4.sin_addr.s_addr;
851
852 return jhash_3words(addr, ((__u32)paddr->v4.sin_port) << 16 |
853 (__force __u32)lport, net_hash_mix(net), seed);
854}
855
856static const struct rhashtable_params sctp_hash_params = {
857 .head_offset = offsetof(struct sctp_transport, node),
858 .hashfn = sctp_hash_key,
859 .obj_hashfn = sctp_hash_obj,
860 .obj_cmpfn = sctp_hash_cmp,
861 .automatic_shrinking = true,
862};
863
864int sctp_transport_hashtable_init(void)
865{
866 return rhashtable_init(&sctp_transport_hashtable, &sctp_hash_params);
867}
868
869void sctp_transport_hashtable_destroy(void)
870{
871 rhashtable_destroy(&sctp_transport_hashtable);
872}
873
874void sctp_hash_transport(struct sctp_transport *t)
875{
876 struct sctp_hash_cmp_arg arg;
877
878 if (t->asoc->temp)
879 return;
880
881 arg.ep = t->asoc->ep;
882 arg.paddr = &t->ipaddr;
883 arg.net = sock_net(t->asoc->base.sk);
884
885reinsert:
886 if (rhashtable_lookup_insert_key(&sctp_transport_hashtable, &arg,
887 &t->node, sctp_hash_params) == -EBUSY)
888 goto reinsert;
889}
890
891void sctp_unhash_transport(struct sctp_transport *t)
892{
893 if (t->asoc->temp)
894 return;
895
896 rhashtable_remove_fast(&sctp_transport_hashtable, &t->node,
897 sctp_hash_params);
898}
899
900struct sctp_transport *sctp_addrs_lookup_transport(
901 struct net *net,
902 const union sctp_addr *laddr,
903 const union sctp_addr *paddr)
904{
905 struct sctp_hash_cmp_arg arg = {
906 .ep = NULL,
907 .laddr = laddr,
908 .paddr = paddr,
909 .net = net,
910 };
911
912 return rhashtable_lookup_fast(&sctp_transport_hashtable, &arg,
913 sctp_hash_params);
914}
915
916struct sctp_transport *sctp_epaddr_lookup_transport(
917 const struct sctp_endpoint *ep,
918 const union sctp_addr *paddr)
919{
920 struct net *net = sock_net(ep->base.sk);
921 struct sctp_hash_cmp_arg arg = {
922 .ep = ep,
923 .paddr = paddr,
924 .net = net,
925 };
926
927 return rhashtable_lookup_fast(&sctp_transport_hashtable, &arg,
928 sctp_hash_params);
929}
930
931/* Look up an association. */
932static struct sctp_association *__sctp_lookup_association(
933 struct net *net,
934 const union sctp_addr *local,
935 const union sctp_addr *peer,
936 struct sctp_transport **pt)
937{
938 struct sctp_transport *t;
939 struct sctp_association *asoc = NULL;
940
941 t = sctp_addrs_lookup_transport(net, local, peer);
942 if (!t || !sctp_transport_hold(t))
943 goto out;
944
945 asoc = t->asoc;
946 sctp_association_hold(asoc);
947 *pt = t;
948
949 sctp_transport_put(t);
950
951out:
952 return asoc;
953}
954
955/* Look up an association. protected by RCU read lock */
956static
957struct sctp_association *sctp_lookup_association(struct net *net,
958 const union sctp_addr *laddr,
959 const union sctp_addr *paddr,
960 struct sctp_transport **transportp)
961{
962 struct sctp_association *asoc;
963
964 rcu_read_lock();
965 asoc = __sctp_lookup_association(net, laddr, paddr, transportp);
966 rcu_read_unlock();
967
968 return asoc;
969}
970
971/* Is there an association matching the given local and peer addresses? */
972int sctp_has_association(struct net *net,
973 const union sctp_addr *laddr,
974 const union sctp_addr *paddr)
975{
976 struct sctp_association *asoc;
977 struct sctp_transport *transport;
978
979 if ((asoc = sctp_lookup_association(net, laddr, paddr, &transport))) {
980 sctp_association_put(asoc);
981 return 1;
982 }
983
984 return 0;
985}
986
987/*
988 * SCTP Implementors Guide, 2.18 Handling of address
989 * parameters within the INIT or INIT-ACK.
990 *
991 * D) When searching for a matching TCB upon reception of an INIT
992 * or INIT-ACK chunk the receiver SHOULD use not only the
993 * source address of the packet (containing the INIT or
994 * INIT-ACK) but the receiver SHOULD also use all valid
995 * address parameters contained within the chunk.
996 *
997 * 2.18.3 Solution description
998 *
999 * This new text clearly specifies to an implementor the need
1000 * to look within the INIT or INIT-ACK. Any implementation that
1001 * does not do this, may not be able to establish associations
1002 * in certain circumstances.
1003 *
1004 */
1005static struct sctp_association *__sctp_rcv_init_lookup(struct net *net,
1006 struct sk_buff *skb,
1007 const union sctp_addr *laddr, struct sctp_transport **transportp)
1008{
1009 struct sctp_association *asoc;
1010 union sctp_addr addr;
1011 union sctp_addr *paddr = &addr;
1012 struct sctphdr *sh = sctp_hdr(skb);
1013 union sctp_params params;
1014 sctp_init_chunk_t *init;
1015 struct sctp_transport *transport;
1016 struct sctp_af *af;
1017
1018 /*
1019 * This code will NOT touch anything inside the chunk--it is
1020 * strictly READ-ONLY.
1021 *
1022 * RFC 2960 3 SCTP packet Format
1023 *
1024 * Multiple chunks can be bundled into one SCTP packet up to
1025 * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN
1026 * COMPLETE chunks. These chunks MUST NOT be bundled with any
1027 * other chunk in a packet. See Section 6.10 for more details
1028 * on chunk bundling.
1029 */
1030
1031 /* Find the start of the TLVs and the end of the chunk. This is
1032 * the region we search for address parameters.
1033 */
1034 init = (sctp_init_chunk_t *)skb->data;
1035
1036 /* Walk the parameters looking for embedded addresses. */
1037 sctp_walk_params(params, init, init_hdr.params) {
1038
1039 /* Note: Ignoring hostname addresses. */
1040 af = sctp_get_af_specific(param_type2af(params.p->type));
1041 if (!af)
1042 continue;
1043
1044 af->from_addr_param(paddr, params.addr, sh->source, 0);
1045
1046 asoc = __sctp_lookup_association(net, laddr, paddr, &transport);
1047 if (asoc)
1048 return asoc;
1049 }
1050
1051 return NULL;
1052}
1053
1054/* ADD-IP, Section 5.2
1055 * When an endpoint receives an ASCONF Chunk from the remote peer
1056 * special procedures may be needed to identify the association the
1057 * ASCONF Chunk is associated with. To properly find the association
1058 * the following procedures SHOULD be followed:
1059 *
1060 * D2) If the association is not found, use the address found in the
1061 * Address Parameter TLV combined with the port number found in the
1062 * SCTP common header. If found proceed to rule D4.
1063 *
1064 * D2-ext) If more than one ASCONF Chunks are packed together, use the
1065 * address found in the ASCONF Address Parameter TLV of each of the
1066 * subsequent ASCONF Chunks. If found, proceed to rule D4.
1067 */
1068static struct sctp_association *__sctp_rcv_asconf_lookup(
1069 struct net *net,
1070 sctp_chunkhdr_t *ch,
1071 const union sctp_addr *laddr,
1072 __be16 peer_port,
1073 struct sctp_transport **transportp)
1074{
1075 sctp_addip_chunk_t *asconf = (struct sctp_addip_chunk *)ch;
1076 struct sctp_af *af;
1077 union sctp_addr_param *param;
1078 union sctp_addr paddr;
1079
1080 /* Skip over the ADDIP header and find the Address parameter */
1081 param = (union sctp_addr_param *)(asconf + 1);
1082
1083 af = sctp_get_af_specific(param_type2af(param->p.type));
1084 if (unlikely(!af))
1085 return NULL;
1086
1087 af->from_addr_param(&paddr, param, peer_port, 0);
1088
1089 return __sctp_lookup_association(net, laddr, &paddr, transportp);
1090}
1091
1092
1093/* SCTP-AUTH, Section 6.3:
1094* If the receiver does not find a STCB for a packet containing an AUTH
1095* chunk as the first chunk and not a COOKIE-ECHO chunk as the second
1096* chunk, it MUST use the chunks after the AUTH chunk to look up an existing
1097* association.
1098*
1099* This means that any chunks that can help us identify the association need
1100* to be looked at to find this association.
1101*/
1102static struct sctp_association *__sctp_rcv_walk_lookup(struct net *net,
1103 struct sk_buff *skb,
1104 const union sctp_addr *laddr,
1105 struct sctp_transport **transportp)
1106{
1107 struct sctp_association *asoc = NULL;
1108 sctp_chunkhdr_t *ch;
1109 int have_auth = 0;
1110 unsigned int chunk_num = 1;
1111 __u8 *ch_end;
1112
1113 /* Walk through the chunks looking for AUTH or ASCONF chunks
1114 * to help us find the association.
1115 */
1116 ch = (sctp_chunkhdr_t *) skb->data;
1117 do {
1118 /* Break out if chunk length is less then minimal. */
1119 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
1120 break;
1121
1122 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
1123 if (ch_end > skb_tail_pointer(skb))
1124 break;
1125
1126 switch (ch->type) {
1127 case SCTP_CID_AUTH:
1128 have_auth = chunk_num;
1129 break;
1130
1131 case SCTP_CID_COOKIE_ECHO:
1132 /* If a packet arrives containing an AUTH chunk as
1133 * a first chunk, a COOKIE-ECHO chunk as the second
1134 * chunk, and possibly more chunks after them, and
1135 * the receiver does not have an STCB for that
1136 * packet, then authentication is based on
1137 * the contents of the COOKIE- ECHO chunk.
1138 */
1139 if (have_auth == 1 && chunk_num == 2)
1140 return NULL;
1141 break;
1142
1143 case SCTP_CID_ASCONF:
1144 if (have_auth || net->sctp.addip_noauth)
1145 asoc = __sctp_rcv_asconf_lookup(
1146 net, ch, laddr,
1147 sctp_hdr(skb)->source,
1148 transportp);
1149 default:
1150 break;
1151 }
1152
1153 if (asoc)
1154 break;
1155
1156 ch = (sctp_chunkhdr_t *) ch_end;
1157 chunk_num++;
1158 } while (ch_end < skb_tail_pointer(skb));
1159
1160 return asoc;
1161}
1162
1163/*
1164 * There are circumstances when we need to look inside the SCTP packet
1165 * for information to help us find the association. Examples
1166 * include looking inside of INIT/INIT-ACK chunks or after the AUTH
1167 * chunks.
1168 */
1169static struct sctp_association *__sctp_rcv_lookup_harder(struct net *net,
1170 struct sk_buff *skb,
1171 const union sctp_addr *laddr,
1172 struct sctp_transport **transportp)
1173{
1174 sctp_chunkhdr_t *ch;
1175
1176 ch = (sctp_chunkhdr_t *) skb->data;
1177
1178 /* The code below will attempt to walk the chunk and extract
1179 * parameter information. Before we do that, we need to verify
1180 * that the chunk length doesn't cause overflow. Otherwise, we'll
1181 * walk off the end.
1182 */
1183 if (WORD_ROUND(ntohs(ch->length)) > skb->len)
1184 return NULL;
1185
1186 /* If this is INIT/INIT-ACK look inside the chunk too. */
1187 if (ch->type == SCTP_CID_INIT || ch->type == SCTP_CID_INIT_ACK)
1188 return __sctp_rcv_init_lookup(net, skb, laddr, transportp);
1189
1190 return __sctp_rcv_walk_lookup(net, skb, laddr, transportp);
1191}
1192
1193/* Lookup an association for an inbound skb. */
1194static struct sctp_association *__sctp_rcv_lookup(struct net *net,
1195 struct sk_buff *skb,
1196 const union sctp_addr *paddr,
1197 const union sctp_addr *laddr,
1198 struct sctp_transport **transportp)
1199{
1200 struct sctp_association *asoc;
1201
1202 asoc = __sctp_lookup_association(net, laddr, paddr, transportp);
1203
1204 /* Further lookup for INIT/INIT-ACK packets.
1205 * SCTP Implementors Guide, 2.18 Handling of address
1206 * parameters within the INIT or INIT-ACK.
1207 */
1208 if (!asoc)
1209 asoc = __sctp_rcv_lookup_harder(net, skb, laddr, transportp);
1210
1211 return asoc;
1212}
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 IS_ENABLED(CONFIG_IPV6)
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, sk->sk_rcvbuf))
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, sk->sk_rcvbuf);
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 epb->hashent = sctp_ep_hashfn(epb->bind_addr.port);
740
741 head = &sctp_ep_hashtable[epb->hashent];
742
743 sctp_write_lock(&head->lock);
744 hlist_del_init(&epb->node);
745 sctp_write_unlock(&head->lock);
746}
747
748/* Remove endpoint from the hash. Local BH-safe. */
749void sctp_unhash_endpoint(struct sctp_endpoint *ep)
750{
751 sctp_local_bh_disable();
752 __sctp_unhash_endpoint(ep);
753 sctp_local_bh_enable();
754}
755
756/* Look up an endpoint. */
757static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr)
758{
759 struct sctp_hashbucket *head;
760 struct sctp_ep_common *epb;
761 struct sctp_endpoint *ep;
762 struct hlist_node *node;
763 int hash;
764
765 hash = sctp_ep_hashfn(ntohs(laddr->v4.sin_port));
766 head = &sctp_ep_hashtable[hash];
767 read_lock(&head->lock);
768 sctp_for_each_hentry(epb, node, &head->chain) {
769 ep = sctp_ep(epb);
770 if (sctp_endpoint_is_match(ep, laddr))
771 goto hit;
772 }
773
774 ep = sctp_sk((sctp_get_ctl_sock()))->ep;
775
776hit:
777 sctp_endpoint_hold(ep);
778 read_unlock(&head->lock);
779 return ep;
780}
781
782/* Insert association into the hash table. */
783static void __sctp_hash_established(struct sctp_association *asoc)
784{
785 struct sctp_ep_common *epb;
786 struct sctp_hashbucket *head;
787
788 epb = &asoc->base;
789
790 /* Calculate which chain this entry will belong to. */
791 epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port, asoc->peer.port);
792
793 head = &sctp_assoc_hashtable[epb->hashent];
794
795 sctp_write_lock(&head->lock);
796 hlist_add_head(&epb->node, &head->chain);
797 sctp_write_unlock(&head->lock);
798}
799
800/* Add an association to the hash. Local BH-safe. */
801void sctp_hash_established(struct sctp_association *asoc)
802{
803 if (asoc->temp)
804 return;
805
806 sctp_local_bh_disable();
807 __sctp_hash_established(asoc);
808 sctp_local_bh_enable();
809}
810
811/* Remove association from the hash table. */
812static void __sctp_unhash_established(struct sctp_association *asoc)
813{
814 struct sctp_hashbucket *head;
815 struct sctp_ep_common *epb;
816
817 epb = &asoc->base;
818
819 epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port,
820 asoc->peer.port);
821
822 head = &sctp_assoc_hashtable[epb->hashent];
823
824 sctp_write_lock(&head->lock);
825 hlist_del_init(&epb->node);
826 sctp_write_unlock(&head->lock);
827}
828
829/* Remove association from the hash table. Local BH-safe. */
830void sctp_unhash_established(struct sctp_association *asoc)
831{
832 if (asoc->temp)
833 return;
834
835 sctp_local_bh_disable();
836 __sctp_unhash_established(asoc);
837 sctp_local_bh_enable();
838}
839
840/* Look up an association. */
841static struct sctp_association *__sctp_lookup_association(
842 const union sctp_addr *local,
843 const union sctp_addr *peer,
844 struct sctp_transport **pt)
845{
846 struct sctp_hashbucket *head;
847 struct sctp_ep_common *epb;
848 struct sctp_association *asoc;
849 struct sctp_transport *transport;
850 struct hlist_node *node;
851 int hash;
852
853 /* Optimize here for direct hit, only listening connections can
854 * have wildcards anyways.
855 */
856 hash = sctp_assoc_hashfn(ntohs(local->v4.sin_port), ntohs(peer->v4.sin_port));
857 head = &sctp_assoc_hashtable[hash];
858 read_lock(&head->lock);
859 sctp_for_each_hentry(epb, node, &head->chain) {
860 asoc = sctp_assoc(epb);
861 transport = sctp_assoc_is_match(asoc, local, peer);
862 if (transport)
863 goto hit;
864 }
865
866 read_unlock(&head->lock);
867
868 return NULL;
869
870hit:
871 *pt = transport;
872 sctp_association_hold(asoc);
873 read_unlock(&head->lock);
874 return asoc;
875}
876
877/* Look up an association. BH-safe. */
878SCTP_STATIC
879struct sctp_association *sctp_lookup_association(const union sctp_addr *laddr,
880 const union sctp_addr *paddr,
881 struct sctp_transport **transportp)
882{
883 struct sctp_association *asoc;
884
885 sctp_local_bh_disable();
886 asoc = __sctp_lookup_association(laddr, paddr, transportp);
887 sctp_local_bh_enable();
888
889 return asoc;
890}
891
892/* Is there an association matching the given local and peer addresses? */
893int sctp_has_association(const union sctp_addr *laddr,
894 const union sctp_addr *paddr)
895{
896 struct sctp_association *asoc;
897 struct sctp_transport *transport;
898
899 if ((asoc = sctp_lookup_association(laddr, paddr, &transport))) {
900 sctp_association_put(asoc);
901 return 1;
902 }
903
904 return 0;
905}
906
907/*
908 * SCTP Implementors Guide, 2.18 Handling of address
909 * parameters within the INIT or INIT-ACK.
910 *
911 * D) When searching for a matching TCB upon reception of an INIT
912 * or INIT-ACK chunk the receiver SHOULD use not only the
913 * source address of the packet (containing the INIT or
914 * INIT-ACK) but the receiver SHOULD also use all valid
915 * address parameters contained within the chunk.
916 *
917 * 2.18.3 Solution description
918 *
919 * This new text clearly specifies to an implementor the need
920 * to look within the INIT or INIT-ACK. Any implementation that
921 * does not do this, may not be able to establish associations
922 * in certain circumstances.
923 *
924 */
925static struct sctp_association *__sctp_rcv_init_lookup(struct sk_buff *skb,
926 const union sctp_addr *laddr, struct sctp_transport **transportp)
927{
928 struct sctp_association *asoc;
929 union sctp_addr addr;
930 union sctp_addr *paddr = &addr;
931 struct sctphdr *sh = sctp_hdr(skb);
932 union sctp_params params;
933 sctp_init_chunk_t *init;
934 struct sctp_transport *transport;
935 struct sctp_af *af;
936
937 /*
938 * This code will NOT touch anything inside the chunk--it is
939 * strictly READ-ONLY.
940 *
941 * RFC 2960 3 SCTP packet Format
942 *
943 * Multiple chunks can be bundled into one SCTP packet up to
944 * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN
945 * COMPLETE chunks. These chunks MUST NOT be bundled with any
946 * other chunk in a packet. See Section 6.10 for more details
947 * on chunk bundling.
948 */
949
950 /* Find the start of the TLVs and the end of the chunk. This is
951 * the region we search for address parameters.
952 */
953 init = (sctp_init_chunk_t *)skb->data;
954
955 /* Walk the parameters looking for embedded addresses. */
956 sctp_walk_params(params, init, init_hdr.params) {
957
958 /* Note: Ignoring hostname addresses. */
959 af = sctp_get_af_specific(param_type2af(params.p->type));
960 if (!af)
961 continue;
962
963 af->from_addr_param(paddr, params.addr, sh->source, 0);
964
965 asoc = __sctp_lookup_association(laddr, paddr, &transport);
966 if (asoc)
967 return asoc;
968 }
969
970 return NULL;
971}
972
973/* ADD-IP, Section 5.2
974 * When an endpoint receives an ASCONF Chunk from the remote peer
975 * special procedures may be needed to identify the association the
976 * ASCONF Chunk is associated with. To properly find the association
977 * the following procedures SHOULD be followed:
978 *
979 * D2) If the association is not found, use the address found in the
980 * Address Parameter TLV combined with the port number found in the
981 * SCTP common header. If found proceed to rule D4.
982 *
983 * D2-ext) If more than one ASCONF Chunks are packed together, use the
984 * address found in the ASCONF Address Parameter TLV of each of the
985 * subsequent ASCONF Chunks. If found, proceed to rule D4.
986 */
987static struct sctp_association *__sctp_rcv_asconf_lookup(
988 sctp_chunkhdr_t *ch,
989 const union sctp_addr *laddr,
990 __be16 peer_port,
991 struct sctp_transport **transportp)
992{
993 sctp_addip_chunk_t *asconf = (struct sctp_addip_chunk *)ch;
994 struct sctp_af *af;
995 union sctp_addr_param *param;
996 union sctp_addr paddr;
997
998 /* Skip over the ADDIP header and find the Address parameter */
999 param = (union sctp_addr_param *)(asconf + 1);
1000
1001 af = sctp_get_af_specific(param_type2af(param->p.type));
1002 if (unlikely(!af))
1003 return NULL;
1004
1005 af->from_addr_param(&paddr, param, peer_port, 0);
1006
1007 return __sctp_lookup_association(laddr, &paddr, transportp);
1008}
1009
1010
1011/* SCTP-AUTH, Section 6.3:
1012* If the receiver does not find a STCB for a packet containing an AUTH
1013* chunk as the first chunk and not a COOKIE-ECHO chunk as the second
1014* chunk, it MUST use the chunks after the AUTH chunk to look up an existing
1015* association.
1016*
1017* This means that any chunks that can help us identify the association need
1018* to be looked at to find this association.
1019*/
1020static struct sctp_association *__sctp_rcv_walk_lookup(struct sk_buff *skb,
1021 const union sctp_addr *laddr,
1022 struct sctp_transport **transportp)
1023{
1024 struct sctp_association *asoc = NULL;
1025 sctp_chunkhdr_t *ch;
1026 int have_auth = 0;
1027 unsigned int chunk_num = 1;
1028 __u8 *ch_end;
1029
1030 /* Walk through the chunks looking for AUTH or ASCONF chunks
1031 * to help us find the association.
1032 */
1033 ch = (sctp_chunkhdr_t *) skb->data;
1034 do {
1035 /* Break out if chunk length is less then minimal. */
1036 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
1037 break;
1038
1039 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
1040 if (ch_end > skb_tail_pointer(skb))
1041 break;
1042
1043 switch(ch->type) {
1044 case SCTP_CID_AUTH:
1045 have_auth = chunk_num;
1046 break;
1047
1048 case SCTP_CID_COOKIE_ECHO:
1049 /* If a packet arrives containing an AUTH chunk as
1050 * a first chunk, a COOKIE-ECHO chunk as the second
1051 * chunk, and possibly more chunks after them, and
1052 * the receiver does not have an STCB for that
1053 * packet, then authentication is based on
1054 * the contents of the COOKIE- ECHO chunk.
1055 */
1056 if (have_auth == 1 && chunk_num == 2)
1057 return NULL;
1058 break;
1059
1060 case SCTP_CID_ASCONF:
1061 if (have_auth || sctp_addip_noauth)
1062 asoc = __sctp_rcv_asconf_lookup(ch, laddr,
1063 sctp_hdr(skb)->source,
1064 transportp);
1065 default:
1066 break;
1067 }
1068
1069 if (asoc)
1070 break;
1071
1072 ch = (sctp_chunkhdr_t *) ch_end;
1073 chunk_num++;
1074 } while (ch_end < skb_tail_pointer(skb));
1075
1076 return asoc;
1077}
1078
1079/*
1080 * There are circumstances when we need to look inside the SCTP packet
1081 * for information to help us find the association. Examples
1082 * include looking inside of INIT/INIT-ACK chunks or after the AUTH
1083 * chunks.
1084 */
1085static struct sctp_association *__sctp_rcv_lookup_harder(struct sk_buff *skb,
1086 const union sctp_addr *laddr,
1087 struct sctp_transport **transportp)
1088{
1089 sctp_chunkhdr_t *ch;
1090
1091 ch = (sctp_chunkhdr_t *) skb->data;
1092
1093 /* The code below will attempt to walk the chunk and extract
1094 * parameter information. Before we do that, we need to verify
1095 * that the chunk length doesn't cause overflow. Otherwise, we'll
1096 * walk off the end.
1097 */
1098 if (WORD_ROUND(ntohs(ch->length)) > skb->len)
1099 return NULL;
1100
1101 /* If this is INIT/INIT-ACK look inside the chunk too. */
1102 switch (ch->type) {
1103 case SCTP_CID_INIT:
1104 case SCTP_CID_INIT_ACK:
1105 return __sctp_rcv_init_lookup(skb, laddr, transportp);
1106 break;
1107
1108 default:
1109 return __sctp_rcv_walk_lookup(skb, laddr, transportp);
1110 break;
1111 }
1112
1113
1114 return NULL;
1115}
1116
1117/* Lookup an association for an inbound skb. */
1118static struct sctp_association *__sctp_rcv_lookup(struct sk_buff *skb,
1119 const union sctp_addr *paddr,
1120 const union sctp_addr *laddr,
1121 struct sctp_transport **transportp)
1122{
1123 struct sctp_association *asoc;
1124
1125 asoc = __sctp_lookup_association(laddr, paddr, transportp);
1126
1127 /* Further lookup for INIT/INIT-ACK packets.
1128 * SCTP Implementors Guide, 2.18 Handling of address
1129 * parameters within the INIT or INIT-ACK.
1130 */
1131 if (!asoc)
1132 asoc = __sctp_rcv_lookup_harder(skb, laddr, transportp);
1133
1134 return asoc;
1135}