xref: /openbmc/linux/net/sctp/input.c (revision f42b3800)
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 <net/ip.h>
57 #include <net/icmp.h>
58 #include <net/snmp.h>
59 #include <net/sock.h>
60 #include <net/xfrm.h>
61 #include <net/sctp/sctp.h>
62 #include <net/sctp/sm.h>
63 #include <net/sctp/checksum.h>
64 
65 /* Forward declarations for internal helpers. */
66 static int sctp_rcv_ootb(struct sk_buff *);
67 static struct sctp_association *__sctp_rcv_lookup(struct sk_buff *skb,
68 				      const union sctp_addr *laddr,
69 				      const union sctp_addr *paddr,
70 				      struct sctp_transport **transportp);
71 static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr);
72 static struct sctp_association *__sctp_lookup_association(
73 					const union sctp_addr *local,
74 					const union sctp_addr *peer,
75 					struct sctp_transport **pt);
76 
77 static void sctp_add_backlog(struct sock *sk, struct sk_buff *skb);
78 
79 
80 /* Calculate the SCTP checksum of an SCTP packet.  */
81 static inline int sctp_rcv_checksum(struct sk_buff *skb)
82 {
83 	struct sk_buff *list = skb_shinfo(skb)->frag_list;
84 	struct sctphdr *sh = sctp_hdr(skb);
85 	__u32 cmp = ntohl(sh->checksum);
86 	__u32 val = sctp_start_cksum((__u8 *)sh, skb_headlen(skb));
87 
88 	for (; list; list = list->next)
89 		val = sctp_update_cksum((__u8 *)list->data, skb_headlen(list),
90 					val);
91 
92 	val = sctp_end_cksum(val);
93 
94 	if (val != cmp) {
95 		/* CRC failure, dump it. */
96 		SCTP_INC_STATS_BH(SCTP_MIB_CHECKSUMERRORS);
97 		return -1;
98 	}
99 	return 0;
100 }
101 
102 struct sctp_input_cb {
103 	union {
104 		struct inet_skb_parm	h4;
105 #if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
106 		struct inet6_skb_parm	h6;
107 #endif
108 	} header;
109 	struct sctp_chunk *chunk;
110 };
111 #define SCTP_INPUT_CB(__skb)	((struct sctp_input_cb *)&((__skb)->cb[0]))
112 
113 /*
114  * This is the routine which IP calls when receiving an SCTP packet.
115  */
116 int sctp_rcv(struct sk_buff *skb)
117 {
118 	struct sock *sk;
119 	struct sctp_association *asoc;
120 	struct sctp_endpoint *ep = NULL;
121 	struct sctp_ep_common *rcvr;
122 	struct sctp_transport *transport = NULL;
123 	struct sctp_chunk *chunk;
124 	struct sctphdr *sh;
125 	union sctp_addr src;
126 	union sctp_addr dest;
127 	int family;
128 	struct sctp_af *af;
129 
130 	if (skb->pkt_type!=PACKET_HOST)
131 		goto discard_it;
132 
133 	SCTP_INC_STATS_BH(SCTP_MIB_INSCTPPACKS);
134 
135 	if (skb_linearize(skb))
136 		goto discard_it;
137 
138 	sh = sctp_hdr(skb);
139 
140 	/* Pull up the IP and SCTP headers. */
141 	__skb_pull(skb, skb_transport_offset(skb));
142 	if (skb->len < sizeof(struct sctphdr))
143 		goto discard_it;
144 	if (!skb_csum_unnecessary(skb) && sctp_rcv_checksum(skb) < 0)
145 		goto discard_it;
146 
147 	skb_pull(skb, sizeof(struct sctphdr));
148 
149 	/* Make sure we at least have chunk headers worth of data left. */
150 	if (skb->len < sizeof(struct sctp_chunkhdr))
151 		goto discard_it;
152 
153 	family = ipver2af(ip_hdr(skb)->version);
154 	af = sctp_get_af_specific(family);
155 	if (unlikely(!af))
156 		goto discard_it;
157 
158 	/* Initialize local addresses for lookups. */
159 	af->from_skb(&src, skb, 1);
160 	af->from_skb(&dest, skb, 0);
161 
162 	/* If the packet is to or from a non-unicast address,
163 	 * silently discard the packet.
164 	 *
165 	 * This is not clearly defined in the RFC except in section
166 	 * 8.4 - OOTB handling.  However, based on the book "Stream Control
167 	 * Transmission Protocol" 2.1, "It is important to note that the
168 	 * IP address of an SCTP transport address must be a routable
169 	 * unicast address.  In other words, IP multicast addresses and
170 	 * IP broadcast addresses cannot be used in an SCTP transport
171 	 * address."
172 	 */
173 	if (!af->addr_valid(&src, NULL, skb) ||
174 	    !af->addr_valid(&dest, NULL, skb))
175 		goto discard_it;
176 
177 	asoc = __sctp_rcv_lookup(skb, &src, &dest, &transport);
178 
179 	if (!asoc)
180 		ep = __sctp_rcv_lookup_endpoint(&dest);
181 
182 	/* Retrieve the common input handling substructure. */
183 	rcvr = asoc ? &asoc->base : &ep->base;
184 	sk = rcvr->sk;
185 
186 	/*
187 	 * If a frame arrives on an interface and the receiving socket is
188 	 * bound to another interface, via SO_BINDTODEVICE, treat it as OOTB
189 	 */
190 	if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb)))
191 	{
192 		if (asoc) {
193 			sctp_association_put(asoc);
194 			asoc = NULL;
195 		} else {
196 			sctp_endpoint_put(ep);
197 			ep = NULL;
198 		}
199 		sk = sctp_get_ctl_sock();
200 		ep = sctp_sk(sk)->ep;
201 		sctp_endpoint_hold(ep);
202 		rcvr = &ep->base;
203 	}
204 
205 	/*
206 	 * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
207 	 * An SCTP packet is called an "out of the blue" (OOTB)
208 	 * packet if it is correctly formed, i.e., passed the
209 	 * receiver's checksum check, but the receiver is not
210 	 * able to identify the association to which this
211 	 * packet belongs.
212 	 */
213 	if (!asoc) {
214 		if (sctp_rcv_ootb(skb)) {
215 			SCTP_INC_STATS_BH(SCTP_MIB_OUTOFBLUES);
216 			goto discard_release;
217 		}
218 	}
219 
220 	if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family))
221 		goto discard_release;
222 	nf_reset(skb);
223 
224 	if (sk_filter(sk, skb))
225 		goto discard_release;
226 
227 	/* Create an SCTP packet structure. */
228 	chunk = sctp_chunkify(skb, asoc, sk);
229 	if (!chunk)
230 		goto discard_release;
231 	SCTP_INPUT_CB(skb)->chunk = chunk;
232 
233 	/* Remember what endpoint is to handle this packet. */
234 	chunk->rcvr = rcvr;
235 
236 	/* Remember the SCTP header. */
237 	chunk->sctp_hdr = sh;
238 
239 	/* Set the source and destination addresses of the incoming chunk.  */
240 	sctp_init_addrs(chunk, &src, &dest);
241 
242 	/* Remember where we came from.  */
243 	chunk->transport = transport;
244 
245 	/* Acquire access to the sock lock. Note: We are safe from other
246 	 * bottom halves on this lock, but a user may be in the lock too,
247 	 * so check if it is busy.
248 	 */
249 	sctp_bh_lock_sock(sk);
250 
251 	if (sock_owned_by_user(sk)) {
252 		SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_BACKLOG);
253 		sctp_add_backlog(sk, skb);
254 	} else {
255 		SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_SOFTIRQ);
256 		sctp_inq_push(&chunk->rcvr->inqueue, chunk);
257 	}
258 
259 	sctp_bh_unlock_sock(sk);
260 
261 	/* Release the asoc/ep ref we took in the lookup calls. */
262 	if (asoc)
263 		sctp_association_put(asoc);
264 	else
265 		sctp_endpoint_put(ep);
266 
267 	return 0;
268 
269 discard_it:
270 	SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_DISCARDS);
271 	kfree_skb(skb);
272 	return 0;
273 
274 discard_release:
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 	goto discard_it;
282 }
283 
284 /* Process the backlog queue of the socket.  Every skb on
285  * the backlog holds a ref on an association or endpoint.
286  * We hold this ref throughout the state machine to make
287  * sure that the structure we need is still around.
288  */
289 int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
290 {
291 	struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
292 	struct sctp_inq *inqueue = &chunk->rcvr->inqueue;
293 	struct sctp_ep_common *rcvr = NULL;
294 	int backloged = 0;
295 
296 	rcvr = chunk->rcvr;
297 
298 	/* If the rcvr is dead then the association or endpoint
299 	 * has been deleted and we can safely drop the chunk
300 	 * and refs that we are holding.
301 	 */
302 	if (rcvr->dead) {
303 		sctp_chunk_free(chunk);
304 		goto done;
305 	}
306 
307 	if (unlikely(rcvr->sk != sk)) {
308 		/* In this case, the association moved from one socket to
309 		 * another.  We are currently sitting on the backlog of the
310 		 * old socket, so we need to move.
311 		 * However, since we are here in the process context we
312 		 * need to take make sure that the user doesn't own
313 		 * the new socket when we process the packet.
314 		 * If the new socket is user-owned, queue the chunk to the
315 		 * backlog of the new socket without dropping any refs.
316 		 * Otherwise, we can safely push the chunk on the inqueue.
317 		 */
318 
319 		sk = rcvr->sk;
320 		sctp_bh_lock_sock(sk);
321 
322 		if (sock_owned_by_user(sk)) {
323 			sk_add_backlog(sk, skb);
324 			backloged = 1;
325 		} else
326 			sctp_inq_push(inqueue, chunk);
327 
328 		sctp_bh_unlock_sock(sk);
329 
330 		/* If the chunk was backloged again, don't drop refs */
331 		if (backloged)
332 			return 0;
333 	} else {
334 		sctp_inq_push(inqueue, chunk);
335 	}
336 
337 done:
338 	/* Release the refs we took in sctp_add_backlog */
339 	if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
340 		sctp_association_put(sctp_assoc(rcvr));
341 	else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
342 		sctp_endpoint_put(sctp_ep(rcvr));
343 	else
344 		BUG();
345 
346 	return 0;
347 }
348 
349 static void sctp_add_backlog(struct sock *sk, struct sk_buff *skb)
350 {
351 	struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
352 	struct sctp_ep_common *rcvr = chunk->rcvr;
353 
354 	/* Hold the assoc/ep while hanging on the backlog queue.
355 	 * This way, we know structures we need will not disappear from us
356 	 */
357 	if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
358 		sctp_association_hold(sctp_assoc(rcvr));
359 	else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
360 		sctp_endpoint_hold(sctp_ep(rcvr));
361 	else
362 		BUG();
363 
364 	sk_add_backlog(sk, skb);
365 }
366 
367 /* Handle icmp frag needed error. */
368 void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc,
369 			   struct sctp_transport *t, __u32 pmtu)
370 {
371 	if (!t || (t->pathmtu == pmtu))
372 		return;
373 
374 	if (sock_owned_by_user(sk)) {
375 		asoc->pmtu_pending = 1;
376 		t->pmtu_pending = 1;
377 		return;
378 	}
379 
380 	if (t->param_flags & SPP_PMTUD_ENABLE) {
381 		/* Update transports view of the MTU */
382 		sctp_transport_update_pmtu(t, pmtu);
383 
384 		/* Update association pmtu. */
385 		sctp_assoc_sync_pmtu(asoc);
386 	}
387 
388 	/* Retransmit with the new pmtu setting.
389 	 * Normally, if PMTU discovery is disabled, an ICMP Fragmentation
390 	 * Needed will never be sent, but if a message was sent before
391 	 * PMTU discovery was disabled that was larger than the PMTU, it
392 	 * would not be fragmented, so it must be re-transmitted fragmented.
393 	 */
394 	sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD);
395 }
396 
397 /*
398  * SCTP Implementer's Guide, 2.37 ICMP handling procedures
399  *
400  * ICMP8) If the ICMP code is a "Unrecognized next header type encountered"
401  *        or a "Protocol Unreachable" treat this message as an abort
402  *        with the T bit set.
403  *
404  * This function sends an event to the state machine, which will abort the
405  * association.
406  *
407  */
408 void sctp_icmp_proto_unreachable(struct sock *sk,
409 			   struct sctp_association *asoc,
410 			   struct sctp_transport *t)
411 {
412 	SCTP_DEBUG_PRINTK("%s\n",  __func__);
413 
414 	sctp_do_sm(SCTP_EVENT_T_OTHER,
415 		   SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH),
416 		   asoc->state, asoc->ep, asoc, t,
417 		   GFP_ATOMIC);
418 
419 }
420 
421 /* Common lookup code for icmp/icmpv6 error handler. */
422 struct sock *sctp_err_lookup(int family, struct sk_buff *skb,
423 			     struct sctphdr *sctphdr,
424 			     struct sctp_association **app,
425 			     struct sctp_transport **tpp)
426 {
427 	union sctp_addr saddr;
428 	union sctp_addr daddr;
429 	struct sctp_af *af;
430 	struct sock *sk = NULL;
431 	struct sctp_association *asoc;
432 	struct sctp_transport *transport = NULL;
433 
434 	*app = NULL; *tpp = NULL;
435 
436 	af = sctp_get_af_specific(family);
437 	if (unlikely(!af)) {
438 		return NULL;
439 	}
440 
441 	/* Initialize local addresses for lookups. */
442 	af->from_skb(&saddr, skb, 1);
443 	af->from_skb(&daddr, skb, 0);
444 
445 	/* Look for an association that matches the incoming ICMP error
446 	 * packet.
447 	 */
448 	asoc = __sctp_lookup_association(&saddr, &daddr, &transport);
449 	if (!asoc)
450 		return NULL;
451 
452 	sk = asoc->base.sk;
453 
454 	if (ntohl(sctphdr->vtag) != asoc->c.peer_vtag) {
455 		ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
456 		goto out;
457 	}
458 
459 	sctp_bh_lock_sock(sk);
460 
461 	/* If too many ICMPs get dropped on busy
462 	 * servers this needs to be solved differently.
463 	 */
464 	if (sock_owned_by_user(sk))
465 		NET_INC_STATS_BH(LINUX_MIB_LOCKDROPPEDICMPS);
466 
467 	*app = asoc;
468 	*tpp = transport;
469 	return sk;
470 
471 out:
472 	if (asoc)
473 		sctp_association_put(asoc);
474 	return NULL;
475 }
476 
477 /* Common cleanup code for icmp/icmpv6 error handler. */
478 void sctp_err_finish(struct sock *sk, struct sctp_association *asoc)
479 {
480 	sctp_bh_unlock_sock(sk);
481 	if (asoc)
482 		sctp_association_put(asoc);
483 }
484 
485 /*
486  * This routine is called by the ICMP module when it gets some
487  * sort of error condition.  If err < 0 then the socket should
488  * be closed and the error returned to the user.  If err > 0
489  * it's just the icmp type << 8 | icmp code.  After adjustment
490  * header points to the first 8 bytes of the sctp header.  We need
491  * to find the appropriate port.
492  *
493  * The locking strategy used here is very "optimistic". When
494  * someone else accesses the socket the ICMP is just dropped
495  * and for some paths there is no check at all.
496  * A more general error queue to queue errors for later handling
497  * is probably better.
498  *
499  */
500 void sctp_v4_err(struct sk_buff *skb, __u32 info)
501 {
502 	struct iphdr *iph = (struct iphdr *)skb->data;
503 	const int ihlen = iph->ihl * 4;
504 	const int type = icmp_hdr(skb)->type;
505 	const int code = icmp_hdr(skb)->code;
506 	struct sock *sk;
507 	struct sctp_association *asoc = NULL;
508 	struct sctp_transport *transport;
509 	struct inet_sock *inet;
510 	sk_buff_data_t saveip, savesctp;
511 	int err;
512 
513 	if (skb->len < ihlen + 8) {
514 		ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
515 		return;
516 	}
517 
518 	/* Fix up skb to look at the embedded net header. */
519 	saveip = skb->network_header;
520 	savesctp = skb->transport_header;
521 	skb_reset_network_header(skb);
522 	skb_set_transport_header(skb, ihlen);
523 	sk = sctp_err_lookup(AF_INET, skb, sctp_hdr(skb), &asoc, &transport);
524 	/* Put back, the original values. */
525 	skb->network_header = saveip;
526 	skb->transport_header = savesctp;
527 	if (!sk) {
528 		ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
529 		return;
530 	}
531 	/* Warning:  The sock lock is held.  Remember to call
532 	 * sctp_err_finish!
533 	 */
534 
535 	switch (type) {
536 	case ICMP_PARAMETERPROB:
537 		err = EPROTO;
538 		break;
539 	case ICMP_DEST_UNREACH:
540 		if (code > NR_ICMP_UNREACH)
541 			goto out_unlock;
542 
543 		/* PMTU discovery (RFC1191) */
544 		if (ICMP_FRAG_NEEDED == code) {
545 			sctp_icmp_frag_needed(sk, asoc, transport, info);
546 			goto out_unlock;
547 		}
548 		else {
549 			if (ICMP_PROT_UNREACH == code) {
550 				sctp_icmp_proto_unreachable(sk, asoc,
551 							    transport);
552 				goto out_unlock;
553 			}
554 		}
555 		err = icmp_err_convert[code].errno;
556 		break;
557 	case ICMP_TIME_EXCEEDED:
558 		/* Ignore any time exceeded errors due to fragment reassembly
559 		 * timeouts.
560 		 */
561 		if (ICMP_EXC_FRAGTIME == code)
562 			goto out_unlock;
563 
564 		err = EHOSTUNREACH;
565 		break;
566 	default:
567 		goto out_unlock;
568 	}
569 
570 	inet = inet_sk(sk);
571 	if (!sock_owned_by_user(sk) && inet->recverr) {
572 		sk->sk_err = err;
573 		sk->sk_error_report(sk);
574 	} else {  /* Only an error on timeout */
575 		sk->sk_err_soft = err;
576 	}
577 
578 out_unlock:
579 	sctp_err_finish(sk, asoc);
580 }
581 
582 /*
583  * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
584  *
585  * This function scans all the chunks in the OOTB packet to determine if
586  * the packet should be discarded right away.  If a response might be needed
587  * for this packet, or, if further processing is possible, the packet will
588  * be queued to a proper inqueue for the next phase of handling.
589  *
590  * Output:
591  * Return 0 - If further processing is needed.
592  * Return 1 - If the packet can be discarded right away.
593  */
594 static int sctp_rcv_ootb(struct sk_buff *skb)
595 {
596 	sctp_chunkhdr_t *ch;
597 	__u8 *ch_end;
598 	sctp_errhdr_t *err;
599 
600 	ch = (sctp_chunkhdr_t *) skb->data;
601 
602 	/* Scan through all the chunks in the packet.  */
603 	do {
604 		/* Break out if chunk length is less then minimal. */
605 		if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
606 			break;
607 
608 		ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
609 		if (ch_end > skb_tail_pointer(skb))
610 			break;
611 
612 		/* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the
613 		 * receiver MUST silently discard the OOTB packet and take no
614 		 * further action.
615 		 */
616 		if (SCTP_CID_ABORT == ch->type)
617 			goto discard;
618 
619 		/* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE
620 		 * chunk, the receiver should silently discard the packet
621 		 * and take no further action.
622 		 */
623 		if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type)
624 			goto discard;
625 
626 		/* RFC 4460, 2.11.2
627 		 * This will discard packets with INIT chunk bundled as
628 		 * subsequent chunks in the packet.  When INIT is first,
629 		 * the normal INIT processing will discard the chunk.
630 		 */
631 		if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data)
632 			goto discard;
633 
634 		/* RFC 8.4, 7) If the packet contains a "Stale cookie" ERROR
635 		 * or a COOKIE ACK the SCTP Packet should be silently
636 		 * discarded.
637 		 */
638 		if (SCTP_CID_COOKIE_ACK == ch->type)
639 			goto discard;
640 
641 		if (SCTP_CID_ERROR == ch->type) {
642 			sctp_walk_errors(err, ch) {
643 				if (SCTP_ERROR_STALE_COOKIE == err->cause)
644 					goto discard;
645 			}
646 		}
647 
648 		ch = (sctp_chunkhdr_t *) ch_end;
649 	} while (ch_end < skb_tail_pointer(skb));
650 
651 	return 0;
652 
653 discard:
654 	return 1;
655 }
656 
657 /* Insert endpoint into the hash table.  */
658 static void __sctp_hash_endpoint(struct sctp_endpoint *ep)
659 {
660 	struct sctp_ep_common *epb;
661 	struct sctp_hashbucket *head;
662 
663 	epb = &ep->base;
664 
665 	epb->hashent = sctp_ep_hashfn(epb->bind_addr.port);
666 	head = &sctp_ep_hashtable[epb->hashent];
667 
668 	sctp_write_lock(&head->lock);
669 	hlist_add_head(&epb->node, &head->chain);
670 	sctp_write_unlock(&head->lock);
671 }
672 
673 /* Add an endpoint to the hash. Local BH-safe. */
674 void sctp_hash_endpoint(struct sctp_endpoint *ep)
675 {
676 	sctp_local_bh_disable();
677 	__sctp_hash_endpoint(ep);
678 	sctp_local_bh_enable();
679 }
680 
681 /* Remove endpoint from the hash table.  */
682 static void __sctp_unhash_endpoint(struct sctp_endpoint *ep)
683 {
684 	struct sctp_hashbucket *head;
685 	struct sctp_ep_common *epb;
686 
687 	epb = &ep->base;
688 
689 	if (hlist_unhashed(&epb->node))
690 		return;
691 
692 	epb->hashent = sctp_ep_hashfn(epb->bind_addr.port);
693 
694 	head = &sctp_ep_hashtable[epb->hashent];
695 
696 	sctp_write_lock(&head->lock);
697 	__hlist_del(&epb->node);
698 	sctp_write_unlock(&head->lock);
699 }
700 
701 /* Remove endpoint from the hash.  Local BH-safe. */
702 void sctp_unhash_endpoint(struct sctp_endpoint *ep)
703 {
704 	sctp_local_bh_disable();
705 	__sctp_unhash_endpoint(ep);
706 	sctp_local_bh_enable();
707 }
708 
709 /* Look up an endpoint. */
710 static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr)
711 {
712 	struct sctp_hashbucket *head;
713 	struct sctp_ep_common *epb;
714 	struct sctp_endpoint *ep;
715 	struct hlist_node *node;
716 	int hash;
717 
718 	hash = sctp_ep_hashfn(ntohs(laddr->v4.sin_port));
719 	head = &sctp_ep_hashtable[hash];
720 	read_lock(&head->lock);
721 	sctp_for_each_hentry(epb, node, &head->chain) {
722 		ep = sctp_ep(epb);
723 		if (sctp_endpoint_is_match(ep, laddr))
724 			goto hit;
725 	}
726 
727 	ep = sctp_sk((sctp_get_ctl_sock()))->ep;
728 
729 hit:
730 	sctp_endpoint_hold(ep);
731 	read_unlock(&head->lock);
732 	return ep;
733 }
734 
735 /* Insert association into the hash table.  */
736 static void __sctp_hash_established(struct sctp_association *asoc)
737 {
738 	struct sctp_ep_common *epb;
739 	struct sctp_hashbucket *head;
740 
741 	epb = &asoc->base;
742 
743 	/* Calculate which chain this entry will belong to. */
744 	epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port, asoc->peer.port);
745 
746 	head = &sctp_assoc_hashtable[epb->hashent];
747 
748 	sctp_write_lock(&head->lock);
749 	hlist_add_head(&epb->node, &head->chain);
750 	sctp_write_unlock(&head->lock);
751 }
752 
753 /* Add an association to the hash. Local BH-safe. */
754 void sctp_hash_established(struct sctp_association *asoc)
755 {
756 	if (asoc->temp)
757 		return;
758 
759 	sctp_local_bh_disable();
760 	__sctp_hash_established(asoc);
761 	sctp_local_bh_enable();
762 }
763 
764 /* Remove association from the hash table.  */
765 static void __sctp_unhash_established(struct sctp_association *asoc)
766 {
767 	struct sctp_hashbucket *head;
768 	struct sctp_ep_common *epb;
769 
770 	epb = &asoc->base;
771 
772 	epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port,
773 					 asoc->peer.port);
774 
775 	head = &sctp_assoc_hashtable[epb->hashent];
776 
777 	sctp_write_lock(&head->lock);
778 	__hlist_del(&epb->node);
779 	sctp_write_unlock(&head->lock);
780 }
781 
782 /* Remove association from the hash table.  Local BH-safe. */
783 void sctp_unhash_established(struct sctp_association *asoc)
784 {
785 	if (asoc->temp)
786 		return;
787 
788 	sctp_local_bh_disable();
789 	__sctp_unhash_established(asoc);
790 	sctp_local_bh_enable();
791 }
792 
793 /* Look up an association. */
794 static struct sctp_association *__sctp_lookup_association(
795 					const union sctp_addr *local,
796 					const union sctp_addr *peer,
797 					struct sctp_transport **pt)
798 {
799 	struct sctp_hashbucket *head;
800 	struct sctp_ep_common *epb;
801 	struct sctp_association *asoc;
802 	struct sctp_transport *transport;
803 	struct hlist_node *node;
804 	int hash;
805 
806 	/* Optimize here for direct hit, only listening connections can
807 	 * have wildcards anyways.
808 	 */
809 	hash = sctp_assoc_hashfn(ntohs(local->v4.sin_port), ntohs(peer->v4.sin_port));
810 	head = &sctp_assoc_hashtable[hash];
811 	read_lock(&head->lock);
812 	sctp_for_each_hentry(epb, node, &head->chain) {
813 		asoc = sctp_assoc(epb);
814 		transport = sctp_assoc_is_match(asoc, local, peer);
815 		if (transport)
816 			goto hit;
817 	}
818 
819 	read_unlock(&head->lock);
820 
821 	return NULL;
822 
823 hit:
824 	*pt = transport;
825 	sctp_association_hold(asoc);
826 	read_unlock(&head->lock);
827 	return asoc;
828 }
829 
830 /* Look up an association. BH-safe. */
831 SCTP_STATIC
832 struct sctp_association *sctp_lookup_association(const union sctp_addr *laddr,
833 						 const union sctp_addr *paddr,
834 					    struct sctp_transport **transportp)
835 {
836 	struct sctp_association *asoc;
837 
838 	sctp_local_bh_disable();
839 	asoc = __sctp_lookup_association(laddr, paddr, transportp);
840 	sctp_local_bh_enable();
841 
842 	return asoc;
843 }
844 
845 /* Is there an association matching the given local and peer addresses? */
846 int sctp_has_association(const union sctp_addr *laddr,
847 			 const union sctp_addr *paddr)
848 {
849 	struct sctp_association *asoc;
850 	struct sctp_transport *transport;
851 
852 	if ((asoc = sctp_lookup_association(laddr, paddr, &transport))) {
853 		sctp_association_put(asoc);
854 		return 1;
855 	}
856 
857 	return 0;
858 }
859 
860 /*
861  * SCTP Implementors Guide, 2.18 Handling of address
862  * parameters within the INIT or INIT-ACK.
863  *
864  * D) When searching for a matching TCB upon reception of an INIT
865  *    or INIT-ACK chunk the receiver SHOULD use not only the
866  *    source address of the packet (containing the INIT or
867  *    INIT-ACK) but the receiver SHOULD also use all valid
868  *    address parameters contained within the chunk.
869  *
870  * 2.18.3 Solution description
871  *
872  * This new text clearly specifies to an implementor the need
873  * to look within the INIT or INIT-ACK. Any implementation that
874  * does not do this, may not be able to establish associations
875  * in certain circumstances.
876  *
877  */
878 static struct sctp_association *__sctp_rcv_init_lookup(struct sk_buff *skb,
879 	const union sctp_addr *laddr, struct sctp_transport **transportp)
880 {
881 	struct sctp_association *asoc;
882 	union sctp_addr addr;
883 	union sctp_addr *paddr = &addr;
884 	struct sctphdr *sh = sctp_hdr(skb);
885 	sctp_chunkhdr_t *ch;
886 	union sctp_params params;
887 	sctp_init_chunk_t *init;
888 	struct sctp_transport *transport;
889 	struct sctp_af *af;
890 
891 	ch = (sctp_chunkhdr_t *) skb->data;
892 
893 	/*
894 	 * This code will NOT touch anything inside the chunk--it is
895 	 * strictly READ-ONLY.
896 	 *
897 	 * RFC 2960 3  SCTP packet Format
898 	 *
899 	 * Multiple chunks can be bundled into one SCTP packet up to
900 	 * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN
901 	 * COMPLETE chunks.  These chunks MUST NOT be bundled with any
902 	 * other chunk in a packet.  See Section 6.10 for more details
903 	 * on chunk bundling.
904 	 */
905 
906 	/* Find the start of the TLVs and the end of the chunk.  This is
907 	 * the region we search for address parameters.
908 	 */
909 	init = (sctp_init_chunk_t *)skb->data;
910 
911 	/* Walk the parameters looking for embedded addresses. */
912 	sctp_walk_params(params, init, init_hdr.params) {
913 
914 		/* Note: Ignoring hostname addresses. */
915 		af = sctp_get_af_specific(param_type2af(params.p->type));
916 		if (!af)
917 			continue;
918 
919 		af->from_addr_param(paddr, params.addr, sh->source, 0);
920 
921 		asoc = __sctp_lookup_association(laddr, paddr, &transport);
922 		if (asoc)
923 			return asoc;
924 	}
925 
926 	return NULL;
927 }
928 
929 /* ADD-IP, Section 5.2
930  * When an endpoint receives an ASCONF Chunk from the remote peer
931  * special procedures may be needed to identify the association the
932  * ASCONF Chunk is associated with. To properly find the association
933  * the following procedures SHOULD be followed:
934  *
935  * D2) If the association is not found, use the address found in the
936  * Address Parameter TLV combined with the port number found in the
937  * SCTP common header. If found proceed to rule D4.
938  *
939  * D2-ext) If more than one ASCONF Chunks are packed together, use the
940  * address found in the ASCONF Address Parameter TLV of each of the
941  * subsequent ASCONF Chunks. If found, proceed to rule D4.
942  */
943 static struct sctp_association *__sctp_rcv_asconf_lookup(
944 					sctp_chunkhdr_t *ch,
945 					const union sctp_addr *laddr,
946 					__be16 peer_port,
947 					struct sctp_transport **transportp)
948 {
949 	sctp_addip_chunk_t *asconf = (struct sctp_addip_chunk *)ch;
950 	struct sctp_af *af;
951 	union sctp_addr_param *param;
952 	union sctp_addr paddr;
953 
954 	/* Skip over the ADDIP header and find the Address parameter */
955 	param = (union sctp_addr_param *)(asconf + 1);
956 
957 	af = sctp_get_af_specific(param_type2af(param->v4.param_hdr.type));
958 	if (unlikely(!af))
959 		return NULL;
960 
961 	af->from_addr_param(&paddr, param, peer_port, 0);
962 
963 	return __sctp_lookup_association(laddr, &paddr, transportp);
964 }
965 
966 
967 /* SCTP-AUTH, Section 6.3:
968 *    If the receiver does not find a STCB for a packet containing an AUTH
969 *    chunk as the first chunk and not a COOKIE-ECHO chunk as the second
970 *    chunk, it MUST use the chunks after the AUTH chunk to look up an existing
971 *    association.
972 *
973 * This means that any chunks that can help us identify the association need
974 * to be looked at to find this assocation.
975 */
976 static struct sctp_association *__sctp_rcv_walk_lookup(struct sk_buff *skb,
977 				      const union sctp_addr *laddr,
978 				      struct sctp_transport **transportp)
979 {
980 	struct sctp_association *asoc = NULL;
981 	sctp_chunkhdr_t *ch;
982 	int have_auth = 0;
983 	unsigned int chunk_num = 1;
984 	__u8 *ch_end;
985 
986 	/* Walk through the chunks looking for AUTH or ASCONF chunks
987 	 * to help us find the association.
988 	 */
989 	ch = (sctp_chunkhdr_t *) skb->data;
990 	do {
991 		/* Break out if chunk length is less then minimal. */
992 		if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
993 			break;
994 
995 		ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
996 		if (ch_end > skb_tail_pointer(skb))
997 			break;
998 
999 		switch(ch->type) {
1000 		    case SCTP_CID_AUTH:
1001 			    have_auth = chunk_num;
1002 			    break;
1003 
1004 		    case SCTP_CID_COOKIE_ECHO:
1005 			    /* If a packet arrives containing an AUTH chunk as
1006 			     * a first chunk, a COOKIE-ECHO chunk as the second
1007 			     * chunk, and possibly more chunks after them, and
1008 			     * the receiver does not have an STCB for that
1009 			     * packet, then authentication is based on
1010 			     * the contents of the COOKIE- ECHO chunk.
1011 			     */
1012 			    if (have_auth == 1 && chunk_num == 2)
1013 				    return NULL;
1014 			    break;
1015 
1016 		    case SCTP_CID_ASCONF:
1017 			    if (have_auth || sctp_addip_noauth)
1018 				    asoc = __sctp_rcv_asconf_lookup(ch, laddr,
1019 							sctp_hdr(skb)->source,
1020 							transportp);
1021 		    default:
1022 			    break;
1023 		}
1024 
1025 		if (asoc)
1026 			break;
1027 
1028 		ch = (sctp_chunkhdr_t *) ch_end;
1029 		chunk_num++;
1030 	} while (ch_end < skb_tail_pointer(skb));
1031 
1032 	return asoc;
1033 }
1034 
1035 /*
1036  * There are circumstances when we need to look inside the SCTP packet
1037  * for information to help us find the association.   Examples
1038  * include looking inside of INIT/INIT-ACK chunks or after the AUTH
1039  * chunks.
1040  */
1041 static struct sctp_association *__sctp_rcv_lookup_harder(struct sk_buff *skb,
1042 				      const union sctp_addr *laddr,
1043 				      struct sctp_transport **transportp)
1044 {
1045 	sctp_chunkhdr_t *ch;
1046 
1047 	ch = (sctp_chunkhdr_t *) skb->data;
1048 
1049 	/* The code below will attempt to walk the chunk and extract
1050 	 * parameter information.  Before we do that, we need to verify
1051 	 * that the chunk length doesn't cause overflow.  Otherwise, we'll
1052 	 * walk off the end.
1053 	 */
1054 	if (WORD_ROUND(ntohs(ch->length)) > skb->len)
1055 		return NULL;
1056 
1057 	/* If this is INIT/INIT-ACK look inside the chunk too. */
1058 	switch (ch->type) {
1059 	case SCTP_CID_INIT:
1060 	case SCTP_CID_INIT_ACK:
1061 		return __sctp_rcv_init_lookup(skb, laddr, transportp);
1062 		break;
1063 
1064 	default:
1065 		return __sctp_rcv_walk_lookup(skb, laddr, transportp);
1066 		break;
1067 	}
1068 
1069 
1070 	return NULL;
1071 }
1072 
1073 /* Lookup an association for an inbound skb. */
1074 static struct sctp_association *__sctp_rcv_lookup(struct sk_buff *skb,
1075 				      const union sctp_addr *paddr,
1076 				      const union sctp_addr *laddr,
1077 				      struct sctp_transport **transportp)
1078 {
1079 	struct sctp_association *asoc;
1080 
1081 	asoc = __sctp_lookup_association(laddr, paddr, transportp);
1082 
1083 	/* Further lookup for INIT/INIT-ACK packets.
1084 	 * SCTP Implementors Guide, 2.18 Handling of address
1085 	 * parameters within the INIT or INIT-ACK.
1086 	 */
1087 	if (!asoc)
1088 		asoc = __sctp_rcv_lookup_harder(skb, laddr, transportp);
1089 
1090 	return asoc;
1091 }
1092