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1/* SCTP kernel implementation
2 * Copyright (c) 1999-2000 Cisco, Inc.
3 * Copyright (c) 1999-2001 Motorola, Inc.
4 * Copyright (c) 2001-2003 International Business Machines, Corp.
5 * Copyright (c) 2001 Intel Corp.
6 * Copyright (c) 2001 Nokia, Inc.
7 * Copyright (c) 2001 La Monte H.P. Yarroll
8 *
9 * This file is part of the SCTP kernel implementation
10 *
11 * These functions handle all input from the IP layer into SCTP.
12 *
13 * This SCTP implementation is free software;
14 * you can redistribute it and/or modify it under the terms of
15 * the GNU General Public License as published by
16 * the Free Software Foundation; either version 2, or (at your option)
17 * any later version.
18 *
19 * This SCTP implementation is distributed in the hope that it
20 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
21 * ************************
22 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
23 * See the GNU General Public License for more details.
24 *
25 * You should have received a copy of the GNU General Public License
26 * along with GNU CC; see the file COPYING. If not, see
27 * <http://www.gnu.org/licenses/>.
28 *
29 * Please send any bug reports or fixes you make to the
30 * email address(es):
31 * lksctp developers <linux-sctp@vger.kernel.org>
32 *
33 * Written or modified by:
34 * La Monte H.P. Yarroll <piggy@acm.org>
35 * Karl Knutson <karl@athena.chicago.il.us>
36 * Xingang Guo <xingang.guo@intel.com>
37 * Jon Grimm <jgrimm@us.ibm.com>
38 * Hui Huang <hui.huang@nokia.com>
39 * Daisy Chang <daisyc@us.ibm.com>
40 * Sridhar Samudrala <sri@us.ibm.com>
41 * Ardelle Fan <ardelle.fan@intel.com>
42 */
43
44#include <linux/types.h>
45#include <linux/list.h> /* For struct list_head */
46#include <linux/socket.h>
47#include <linux/ip.h>
48#include <linux/time.h> /* For struct timeval */
49#include <linux/slab.h>
50#include <net/ip.h>
51#include <net/icmp.h>
52#include <net/snmp.h>
53#include <net/sock.h>
54#include <net/xfrm.h>
55#include <net/sctp/sctp.h>
56#include <net/sctp/sm.h>
57#include <net/sctp/checksum.h>
58#include <net/net_namespace.h>
59
60/* Forward declarations for internal helpers. */
61static int sctp_rcv_ootb(struct sk_buff *);
62static struct sctp_association *__sctp_rcv_lookup(struct net *net,
63 struct sk_buff *skb,
64 const union sctp_addr *paddr,
65 const union sctp_addr *laddr,
66 struct sctp_transport **transportp);
67static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(struct net *net,
68 const union sctp_addr *laddr);
69static struct sctp_association *__sctp_lookup_association(
70 struct net *net,
71 const union sctp_addr *local,
72 const union sctp_addr *peer,
73 struct sctp_transport **pt);
74
75static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb);
76
77
78/* Calculate the SCTP checksum of an SCTP packet. */
79static inline int sctp_rcv_checksum(struct net *net, struct sk_buff *skb)
80{
81 struct sctphdr *sh = sctp_hdr(skb);
82 __le32 cmp = sh->checksum;
83 __le32 val = sctp_compute_cksum(skb, 0);
84
85 if (val != cmp) {
86 /* CRC failure, dump it. */
87 SCTP_INC_STATS_BH(net, SCTP_MIB_CHECKSUMERRORS);
88 return -1;
89 }
90 return 0;
91}
92
93struct sctp_input_cb {
94 union {
95 struct inet_skb_parm h4;
96#if IS_ENABLED(CONFIG_IPV6)
97 struct inet6_skb_parm h6;
98#endif
99 } header;
100 struct sctp_chunk *chunk;
101};
102#define SCTP_INPUT_CB(__skb) ((struct sctp_input_cb *)&((__skb)->cb[0]))
103
104/*
105 * This is the routine which IP calls when receiving an SCTP packet.
106 */
107int sctp_rcv(struct sk_buff *skb)
108{
109 struct sock *sk;
110 struct sctp_association *asoc;
111 struct sctp_endpoint *ep = NULL;
112 struct sctp_ep_common *rcvr;
113 struct sctp_transport *transport = NULL;
114 struct sctp_chunk *chunk;
115 struct sctphdr *sh;
116 union sctp_addr src;
117 union sctp_addr dest;
118 int family;
119 struct sctp_af *af;
120 struct net *net = dev_net(skb->dev);
121
122 if (skb->pkt_type != PACKET_HOST)
123 goto discard_it;
124
125 SCTP_INC_STATS_BH(net, SCTP_MIB_INSCTPPACKS);
126
127 if (skb_linearize(skb))
128 goto discard_it;
129
130 sh = sctp_hdr(skb);
131
132 /* Pull up the IP and SCTP headers. */
133 __skb_pull(skb, skb_transport_offset(skb));
134 if (skb->len < sizeof(struct sctphdr))
135 goto discard_it;
136 if (!sctp_checksum_disable && !skb_csum_unnecessary(skb) &&
137 sctp_rcv_checksum(net, skb) < 0)
138 goto discard_it;
139
140 skb_pull(skb, sizeof(struct sctphdr));
141
142 /* Make sure we at least have chunk headers worth of data left. */
143 if (skb->len < sizeof(struct sctp_chunkhdr))
144 goto discard_it;
145
146 family = ipver2af(ip_hdr(skb)->version);
147 af = sctp_get_af_specific(family);
148 if (unlikely(!af))
149 goto discard_it;
150
151 /* Initialize local addresses for lookups. */
152 af->from_skb(&src, skb, 1);
153 af->from_skb(&dest, skb, 0);
154
155 /* If the packet is to or from a non-unicast address,
156 * silently discard the packet.
157 *
158 * This is not clearly defined in the RFC except in section
159 * 8.4 - OOTB handling. However, based on the book "Stream Control
160 * Transmission Protocol" 2.1, "It is important to note that the
161 * IP address of an SCTP transport address must be a routable
162 * unicast address. In other words, IP multicast addresses and
163 * IP broadcast addresses cannot be used in an SCTP transport
164 * address."
165 */
166 if (!af->addr_valid(&src, NULL, skb) ||
167 !af->addr_valid(&dest, NULL, skb))
168 goto discard_it;
169
170 asoc = __sctp_rcv_lookup(net, skb, &src, &dest, &transport);
171
172 if (!asoc)
173 ep = __sctp_rcv_lookup_endpoint(net, &dest);
174
175 /* Retrieve the common input handling substructure. */
176 rcvr = asoc ? &asoc->base : &ep->base;
177 sk = rcvr->sk;
178
179 /*
180 * If a frame arrives on an interface and the receiving socket is
181 * bound to another interface, via SO_BINDTODEVICE, treat it as OOTB
182 */
183 if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb))) {
184 if (asoc) {
185 sctp_association_put(asoc);
186 asoc = NULL;
187 } else {
188 sctp_endpoint_put(ep);
189 ep = NULL;
190 }
191 sk = net->sctp.ctl_sock;
192 ep = sctp_sk(sk)->ep;
193 sctp_endpoint_hold(ep);
194 rcvr = &ep->base;
195 }
196
197 /*
198 * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
199 * An SCTP packet is called an "out of the blue" (OOTB)
200 * packet if it is correctly formed, i.e., passed the
201 * receiver's checksum check, but the receiver is not
202 * able to identify the association to which this
203 * packet belongs.
204 */
205 if (!asoc) {
206 if (sctp_rcv_ootb(skb)) {
207 SCTP_INC_STATS_BH(net, SCTP_MIB_OUTOFBLUES);
208 goto discard_release;
209 }
210 }
211
212 if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family))
213 goto discard_release;
214 nf_reset(skb);
215
216 if (sk_filter(sk, skb))
217 goto discard_release;
218
219 /* Create an SCTP packet structure. */
220 chunk = sctp_chunkify(skb, asoc, sk);
221 if (!chunk)
222 goto discard_release;
223 SCTP_INPUT_CB(skb)->chunk = chunk;
224
225 /* Remember what endpoint is to handle this packet. */
226 chunk->rcvr = rcvr;
227
228 /* Remember the SCTP header. */
229 chunk->sctp_hdr = sh;
230
231 /* Set the source and destination addresses of the incoming chunk. */
232 sctp_init_addrs(chunk, &src, &dest);
233
234 /* Remember where we came from. */
235 chunk->transport = transport;
236
237 /* Acquire access to the sock lock. Note: We are safe from other
238 * bottom halves on this lock, but a user may be in the lock too,
239 * so check if it is busy.
240 */
241 bh_lock_sock(sk);
242
243 if (sk != rcvr->sk) {
244 /* Our cached sk is different from the rcvr->sk. This is
245 * because migrate()/accept() may have moved the association
246 * to a new socket and released all the sockets. So now we
247 * are holding a lock on the old socket while the user may
248 * be doing something with the new socket. Switch our veiw
249 * of the current sk.
250 */
251 bh_unlock_sock(sk);
252 sk = rcvr->sk;
253 bh_lock_sock(sk);
254 }
255
256 if (sock_owned_by_user(sk)) {
257 if (sctp_add_backlog(sk, skb)) {
258 bh_unlock_sock(sk);
259 sctp_chunk_free(chunk);
260 skb = NULL; /* sctp_chunk_free already freed the skb */
261 goto discard_release;
262 }
263 SCTP_INC_STATS_BH(net, SCTP_MIB_IN_PKT_BACKLOG);
264 } else {
265 SCTP_INC_STATS_BH(net, SCTP_MIB_IN_PKT_SOFTIRQ);
266 sctp_inq_push(&chunk->rcvr->inqueue, chunk);
267 }
268
269 bh_unlock_sock(sk);
270
271 /* Release the asoc/ep ref we took in the lookup calls. */
272 if (asoc)
273 sctp_association_put(asoc);
274 else
275 sctp_endpoint_put(ep);
276
277 return 0;
278
279discard_it:
280 SCTP_INC_STATS_BH(net, SCTP_MIB_IN_PKT_DISCARDS);
281 kfree_skb(skb);
282 return 0;
283
284discard_release:
285 /* Release the asoc/ep ref we took in the lookup calls. */
286 if (asoc)
287 sctp_association_put(asoc);
288 else
289 sctp_endpoint_put(ep);
290
291 goto discard_it;
292}
293
294/* Process the backlog queue of the socket. Every skb on
295 * the backlog holds a ref on an association or endpoint.
296 * We hold this ref throughout the state machine to make
297 * sure that the structure we need is still around.
298 */
299int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
300{
301 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
302 struct sctp_inq *inqueue = &chunk->rcvr->inqueue;
303 struct sctp_ep_common *rcvr = NULL;
304 int backloged = 0;
305
306 rcvr = chunk->rcvr;
307
308 /* If the rcvr is dead then the association or endpoint
309 * has been deleted and we can safely drop the chunk
310 * and refs that we are holding.
311 */
312 if (rcvr->dead) {
313 sctp_chunk_free(chunk);
314 goto done;
315 }
316
317 if (unlikely(rcvr->sk != sk)) {
318 /* In this case, the association moved from one socket to
319 * another. We are currently sitting on the backlog of the
320 * old socket, so we need to move.
321 * However, since we are here in the process context we
322 * need to take make sure that the user doesn't own
323 * the new socket when we process the packet.
324 * If the new socket is user-owned, queue the chunk to the
325 * backlog of the new socket without dropping any refs.
326 * Otherwise, we can safely push the chunk on the inqueue.
327 */
328
329 sk = rcvr->sk;
330 bh_lock_sock(sk);
331
332 if (sock_owned_by_user(sk)) {
333 if (sk_add_backlog(sk, skb, sk->sk_rcvbuf))
334 sctp_chunk_free(chunk);
335 else
336 backloged = 1;
337 } else
338 sctp_inq_push(inqueue, chunk);
339
340 bh_unlock_sock(sk);
341
342 /* If the chunk was backloged again, don't drop refs */
343 if (backloged)
344 return 0;
345 } else {
346 sctp_inq_push(inqueue, chunk);
347 }
348
349done:
350 /* Release the refs we took in sctp_add_backlog */
351 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
352 sctp_association_put(sctp_assoc(rcvr));
353 else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
354 sctp_endpoint_put(sctp_ep(rcvr));
355 else
356 BUG();
357
358 return 0;
359}
360
361static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb)
362{
363 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
364 struct sctp_ep_common *rcvr = chunk->rcvr;
365 int ret;
366
367 ret = sk_add_backlog(sk, skb, sk->sk_rcvbuf);
368 if (!ret) {
369 /* Hold the assoc/ep while hanging on the backlog queue.
370 * This way, we know structures we need will not disappear
371 * from us
372 */
373 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
374 sctp_association_hold(sctp_assoc(rcvr));
375 else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
376 sctp_endpoint_hold(sctp_ep(rcvr));
377 else
378 BUG();
379 }
380 return ret;
381
382}
383
384/* Handle icmp frag needed error. */
385void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc,
386 struct sctp_transport *t, __u32 pmtu)
387{
388 if (!t || (t->pathmtu <= pmtu))
389 return;
390
391 if (sock_owned_by_user(sk)) {
392 asoc->pmtu_pending = 1;
393 t->pmtu_pending = 1;
394 return;
395 }
396
397 if (t->param_flags & SPP_PMTUD_ENABLE) {
398 /* Update transports view of the MTU */
399 sctp_transport_update_pmtu(sk, t, pmtu);
400
401 /* Update association pmtu. */
402 sctp_assoc_sync_pmtu(sk, asoc);
403 }
404
405 /* Retransmit with the new pmtu setting.
406 * Normally, if PMTU discovery is disabled, an ICMP Fragmentation
407 * Needed will never be sent, but if a message was sent before
408 * PMTU discovery was disabled that was larger than the PMTU, it
409 * would not be fragmented, so it must be re-transmitted fragmented.
410 */
411 sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD);
412}
413
414void sctp_icmp_redirect(struct sock *sk, struct sctp_transport *t,
415 struct sk_buff *skb)
416{
417 struct dst_entry *dst;
418
419 if (!t)
420 return;
421 dst = sctp_transport_dst_check(t);
422 if (dst)
423 dst->ops->redirect(dst, sk, skb);
424}
425
426/*
427 * SCTP Implementer's Guide, 2.37 ICMP handling procedures
428 *
429 * ICMP8) If the ICMP code is a "Unrecognized next header type encountered"
430 * or a "Protocol Unreachable" treat this message as an abort
431 * with the T bit set.
432 *
433 * This function sends an event to the state machine, which will abort the
434 * association.
435 *
436 */
437void sctp_icmp_proto_unreachable(struct sock *sk,
438 struct sctp_association *asoc,
439 struct sctp_transport *t)
440{
441 if (sock_owned_by_user(sk)) {
442 if (timer_pending(&t->proto_unreach_timer))
443 return;
444 else {
445 if (!mod_timer(&t->proto_unreach_timer,
446 jiffies + (HZ/20)))
447 sctp_association_hold(asoc);
448 }
449 } else {
450 struct net *net = sock_net(sk);
451
452 pr_debug("%s: unrecognized next header type "
453 "encountered!\n", __func__);
454
455 if (del_timer(&t->proto_unreach_timer))
456 sctp_association_put(asoc);
457
458 sctp_do_sm(net, SCTP_EVENT_T_OTHER,
459 SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH),
460 asoc->state, asoc->ep, asoc, t,
461 GFP_ATOMIC);
462 }
463}
464
465/* Common lookup code for icmp/icmpv6 error handler. */
466struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *skb,
467 struct sctphdr *sctphdr,
468 struct sctp_association **app,
469 struct sctp_transport **tpp)
470{
471 union sctp_addr saddr;
472 union sctp_addr daddr;
473 struct sctp_af *af;
474 struct sock *sk = NULL;
475 struct sctp_association *asoc;
476 struct sctp_transport *transport = NULL;
477 struct sctp_init_chunk *chunkhdr;
478 __u32 vtag = ntohl(sctphdr->vtag);
479 int len = skb->len - ((void *)sctphdr - (void *)skb->data);
480
481 *app = NULL; *tpp = NULL;
482
483 af = sctp_get_af_specific(family);
484 if (unlikely(!af)) {
485 return NULL;
486 }
487
488 /* Initialize local addresses for lookups. */
489 af->from_skb(&saddr, skb, 1);
490 af->from_skb(&daddr, skb, 0);
491
492 /* Look for an association that matches the incoming ICMP error
493 * packet.
494 */
495 asoc = __sctp_lookup_association(net, &saddr, &daddr, &transport);
496 if (!asoc)
497 return NULL;
498
499 sk = asoc->base.sk;
500
501 /* RFC 4960, Appendix C. ICMP Handling
502 *
503 * ICMP6) An implementation MUST validate that the Verification Tag
504 * contained in the ICMP message matches the Verification Tag of
505 * the peer. If the Verification Tag is not 0 and does NOT
506 * match, discard the ICMP message. If it is 0 and the ICMP
507 * message contains enough bytes to verify that the chunk type is
508 * an INIT chunk and that the Initiate Tag matches the tag of the
509 * peer, continue with ICMP7. If the ICMP message is too short
510 * or the chunk type or the Initiate Tag does not match, silently
511 * discard the packet.
512 */
513 if (vtag == 0) {
514 chunkhdr = (void *)sctphdr + sizeof(struct sctphdr);
515 if (len < sizeof(struct sctphdr) + sizeof(sctp_chunkhdr_t)
516 + sizeof(__be32) ||
517 chunkhdr->chunk_hdr.type != SCTP_CID_INIT ||
518 ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag) {
519 goto out;
520 }
521 } else if (vtag != asoc->c.peer_vtag) {
522 goto out;
523 }
524
525 bh_lock_sock(sk);
526
527 /* If too many ICMPs get dropped on busy
528 * servers this needs to be solved differently.
529 */
530 if (sock_owned_by_user(sk))
531 NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
532
533 *app = asoc;
534 *tpp = transport;
535 return sk;
536
537out:
538 sctp_association_put(asoc);
539 return NULL;
540}
541
542/* Common cleanup code for icmp/icmpv6 error handler. */
543void sctp_err_finish(struct sock *sk, struct sctp_association *asoc)
544{
545 bh_unlock_sock(sk);
546 sctp_association_put(asoc);
547}
548
549/*
550 * This routine is called by the ICMP module when it gets some
551 * sort of error condition. If err < 0 then the socket should
552 * be closed and the error returned to the user. If err > 0
553 * it's just the icmp type << 8 | icmp code. After adjustment
554 * header points to the first 8 bytes of the sctp header. We need
555 * to find the appropriate port.
556 *
557 * The locking strategy used here is very "optimistic". When
558 * someone else accesses the socket the ICMP is just dropped
559 * and for some paths there is no check at all.
560 * A more general error queue to queue errors for later handling
561 * is probably better.
562 *
563 */
564void sctp_v4_err(struct sk_buff *skb, __u32 info)
565{
566 const struct iphdr *iph = (const struct iphdr *)skb->data;
567 const int ihlen = iph->ihl * 4;
568 const int type = icmp_hdr(skb)->type;
569 const int code = icmp_hdr(skb)->code;
570 struct sock *sk;
571 struct sctp_association *asoc = NULL;
572 struct sctp_transport *transport;
573 struct inet_sock *inet;
574 __u16 saveip, savesctp;
575 int err;
576 struct net *net = dev_net(skb->dev);
577
578 if (skb->len < ihlen + 8) {
579 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
580 return;
581 }
582
583 /* Fix up skb to look at the embedded net header. */
584 saveip = skb->network_header;
585 savesctp = skb->transport_header;
586 skb_reset_network_header(skb);
587 skb_set_transport_header(skb, ihlen);
588 sk = sctp_err_lookup(net, AF_INET, skb, sctp_hdr(skb), &asoc, &transport);
589 /* Put back, the original values. */
590 skb->network_header = saveip;
591 skb->transport_header = savesctp;
592 if (!sk) {
593 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
594 return;
595 }
596 /* Warning: The sock lock is held. Remember to call
597 * sctp_err_finish!
598 */
599
600 switch (type) {
601 case ICMP_PARAMETERPROB:
602 err = EPROTO;
603 break;
604 case ICMP_DEST_UNREACH:
605 if (code > NR_ICMP_UNREACH)
606 goto out_unlock;
607
608 /* PMTU discovery (RFC1191) */
609 if (ICMP_FRAG_NEEDED == code) {
610 sctp_icmp_frag_needed(sk, asoc, transport, info);
611 goto out_unlock;
612 } else {
613 if (ICMP_PROT_UNREACH == code) {
614 sctp_icmp_proto_unreachable(sk, asoc,
615 transport);
616 goto out_unlock;
617 }
618 }
619 err = icmp_err_convert[code].errno;
620 break;
621 case ICMP_TIME_EXCEEDED:
622 /* Ignore any time exceeded errors due to fragment reassembly
623 * timeouts.
624 */
625 if (ICMP_EXC_FRAGTIME == code)
626 goto out_unlock;
627
628 err = EHOSTUNREACH;
629 break;
630 case ICMP_REDIRECT:
631 sctp_icmp_redirect(sk, transport, skb);
632 /* Fall through to out_unlock. */
633 default:
634 goto out_unlock;
635 }
636
637 inet = inet_sk(sk);
638 if (!sock_owned_by_user(sk) && inet->recverr) {
639 sk->sk_err = err;
640 sk->sk_error_report(sk);
641 } else { /* Only an error on timeout */
642 sk->sk_err_soft = err;
643 }
644
645out_unlock:
646 sctp_err_finish(sk, asoc);
647}
648
649/*
650 * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
651 *
652 * This function scans all the chunks in the OOTB packet to determine if
653 * the packet should be discarded right away. If a response might be needed
654 * for this packet, or, if further processing is possible, the packet will
655 * be queued to a proper inqueue for the next phase of handling.
656 *
657 * Output:
658 * Return 0 - If further processing is needed.
659 * Return 1 - If the packet can be discarded right away.
660 */
661static int sctp_rcv_ootb(struct sk_buff *skb)
662{
663 sctp_chunkhdr_t *ch;
664 __u8 *ch_end;
665
666 ch = (sctp_chunkhdr_t *) skb->data;
667
668 /* Scan through all the chunks in the packet. */
669 do {
670 /* Break out if chunk length is less then minimal. */
671 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
672 break;
673
674 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
675 if (ch_end > skb_tail_pointer(skb))
676 break;
677
678 /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the
679 * receiver MUST silently discard the OOTB packet and take no
680 * further action.
681 */
682 if (SCTP_CID_ABORT == ch->type)
683 goto discard;
684
685 /* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE
686 * chunk, the receiver should silently discard the packet
687 * and take no further action.
688 */
689 if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type)
690 goto discard;
691
692 /* RFC 4460, 2.11.2
693 * This will discard packets with INIT chunk bundled as
694 * subsequent chunks in the packet. When INIT is first,
695 * the normal INIT processing will discard the chunk.
696 */
697 if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data)
698 goto discard;
699
700 ch = (sctp_chunkhdr_t *) ch_end;
701 } while (ch_end < skb_tail_pointer(skb));
702
703 return 0;
704
705discard:
706 return 1;
707}
708
709/* Insert endpoint into the hash table. */
710static void __sctp_hash_endpoint(struct sctp_endpoint *ep)
711{
712 struct net *net = sock_net(ep->base.sk);
713 struct sctp_ep_common *epb;
714 struct sctp_hashbucket *head;
715
716 epb = &ep->base;
717
718 epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port);
719 head = &sctp_ep_hashtable[epb->hashent];
720
721 write_lock(&head->lock);
722 hlist_add_head(&epb->node, &head->chain);
723 write_unlock(&head->lock);
724}
725
726/* Add an endpoint to the hash. Local BH-safe. */
727void sctp_hash_endpoint(struct sctp_endpoint *ep)
728{
729 local_bh_disable();
730 __sctp_hash_endpoint(ep);
731 local_bh_enable();
732}
733
734/* Remove endpoint from the hash table. */
735static void __sctp_unhash_endpoint(struct sctp_endpoint *ep)
736{
737 struct net *net = sock_net(ep->base.sk);
738 struct sctp_hashbucket *head;
739 struct sctp_ep_common *epb;
740
741 epb = &ep->base;
742
743 epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port);
744
745 head = &sctp_ep_hashtable[epb->hashent];
746
747 write_lock(&head->lock);
748 hlist_del_init(&epb->node);
749 write_unlock(&head->lock);
750}
751
752/* Remove endpoint from the hash. Local BH-safe. */
753void sctp_unhash_endpoint(struct sctp_endpoint *ep)
754{
755 local_bh_disable();
756 __sctp_unhash_endpoint(ep);
757 local_bh_enable();
758}
759
760/* Look up an endpoint. */
761static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(struct net *net,
762 const union sctp_addr *laddr)
763{
764 struct sctp_hashbucket *head;
765 struct sctp_ep_common *epb;
766 struct sctp_endpoint *ep;
767 int hash;
768
769 hash = sctp_ep_hashfn(net, ntohs(laddr->v4.sin_port));
770 head = &sctp_ep_hashtable[hash];
771 read_lock(&head->lock);
772 sctp_for_each_hentry(epb, &head->chain) {
773 ep = sctp_ep(epb);
774 if (sctp_endpoint_is_match(ep, net, laddr))
775 goto hit;
776 }
777
778 ep = sctp_sk(net->sctp.ctl_sock)->ep;
779
780hit:
781 sctp_endpoint_hold(ep);
782 read_unlock(&head->lock);
783 return ep;
784}
785
786/* Insert association into the hash table. */
787static void __sctp_hash_established(struct sctp_association *asoc)
788{
789 struct net *net = sock_net(asoc->base.sk);
790 struct sctp_ep_common *epb;
791 struct sctp_hashbucket *head;
792
793 epb = &asoc->base;
794
795 /* Calculate which chain this entry will belong to. */
796 epb->hashent = sctp_assoc_hashfn(net, epb->bind_addr.port,
797 asoc->peer.port);
798
799 head = &sctp_assoc_hashtable[epb->hashent];
800
801 write_lock(&head->lock);
802 hlist_add_head(&epb->node, &head->chain);
803 write_unlock(&head->lock);
804}
805
806/* Add an association to the hash. Local BH-safe. */
807void sctp_hash_established(struct sctp_association *asoc)
808{
809 if (asoc->temp)
810 return;
811
812 local_bh_disable();
813 __sctp_hash_established(asoc);
814 local_bh_enable();
815}
816
817/* Remove association from the hash table. */
818static void __sctp_unhash_established(struct sctp_association *asoc)
819{
820 struct net *net = sock_net(asoc->base.sk);
821 struct sctp_hashbucket *head;
822 struct sctp_ep_common *epb;
823
824 epb = &asoc->base;
825
826 epb->hashent = sctp_assoc_hashfn(net, epb->bind_addr.port,
827 asoc->peer.port);
828
829 head = &sctp_assoc_hashtable[epb->hashent];
830
831 write_lock(&head->lock);
832 hlist_del_init(&epb->node);
833 write_unlock(&head->lock);
834}
835
836/* Remove association from the hash table. Local BH-safe. */
837void sctp_unhash_established(struct sctp_association *asoc)
838{
839 if (asoc->temp)
840 return;
841
842 local_bh_disable();
843 __sctp_unhash_established(asoc);
844 local_bh_enable();
845}
846
847/* Look up an association. */
848static struct sctp_association *__sctp_lookup_association(
849 struct net *net,
850 const union sctp_addr *local,
851 const union sctp_addr *peer,
852 struct sctp_transport **pt)
853{
854 struct sctp_hashbucket *head;
855 struct sctp_ep_common *epb;
856 struct sctp_association *asoc;
857 struct sctp_transport *transport;
858 int hash;
859
860 /* Optimize here for direct hit, only listening connections can
861 * have wildcards anyways.
862 */
863 hash = sctp_assoc_hashfn(net, ntohs(local->v4.sin_port),
864 ntohs(peer->v4.sin_port));
865 head = &sctp_assoc_hashtable[hash];
866 read_lock(&head->lock);
867 sctp_for_each_hentry(epb, &head->chain) {
868 asoc = sctp_assoc(epb);
869 transport = sctp_assoc_is_match(asoc, net, local, peer);
870 if (transport)
871 goto hit;
872 }
873
874 read_unlock(&head->lock);
875
876 return NULL;
877
878hit:
879 *pt = transport;
880 sctp_association_hold(asoc);
881 read_unlock(&head->lock);
882 return asoc;
883}
884
885/* Look up an association. BH-safe. */
886static
887struct sctp_association *sctp_lookup_association(struct net *net,
888 const union sctp_addr *laddr,
889 const union sctp_addr *paddr,
890 struct sctp_transport **transportp)
891{
892 struct sctp_association *asoc;
893
894 local_bh_disable();
895 asoc = __sctp_lookup_association(net, laddr, paddr, transportp);
896 local_bh_enable();
897
898 return asoc;
899}
900
901/* Is there an association matching the given local and peer addresses? */
902int sctp_has_association(struct net *net,
903 const union sctp_addr *laddr,
904 const union sctp_addr *paddr)
905{
906 struct sctp_association *asoc;
907 struct sctp_transport *transport;
908
909 if ((asoc = sctp_lookup_association(net, laddr, paddr, &transport))) {
910 sctp_association_put(asoc);
911 return 1;
912 }
913
914 return 0;
915}
916
917/*
918 * SCTP Implementors Guide, 2.18 Handling of address
919 * parameters within the INIT or INIT-ACK.
920 *
921 * D) When searching for a matching TCB upon reception of an INIT
922 * or INIT-ACK chunk the receiver SHOULD use not only the
923 * source address of the packet (containing the INIT or
924 * INIT-ACK) but the receiver SHOULD also use all valid
925 * address parameters contained within the chunk.
926 *
927 * 2.18.3 Solution description
928 *
929 * This new text clearly specifies to an implementor the need
930 * to look within the INIT or INIT-ACK. Any implementation that
931 * does not do this, may not be able to establish associations
932 * in certain circumstances.
933 *
934 */
935static struct sctp_association *__sctp_rcv_init_lookup(struct net *net,
936 struct sk_buff *skb,
937 const union sctp_addr *laddr, struct sctp_transport **transportp)
938{
939 struct sctp_association *asoc;
940 union sctp_addr addr;
941 union sctp_addr *paddr = &addr;
942 struct sctphdr *sh = sctp_hdr(skb);
943 union sctp_params params;
944 sctp_init_chunk_t *init;
945 struct sctp_transport *transport;
946 struct sctp_af *af;
947
948 /*
949 * This code will NOT touch anything inside the chunk--it is
950 * strictly READ-ONLY.
951 *
952 * RFC 2960 3 SCTP packet Format
953 *
954 * Multiple chunks can be bundled into one SCTP packet up to
955 * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN
956 * COMPLETE chunks. These chunks MUST NOT be bundled with any
957 * other chunk in a packet. See Section 6.10 for more details
958 * on chunk bundling.
959 */
960
961 /* Find the start of the TLVs and the end of the chunk. This is
962 * the region we search for address parameters.
963 */
964 init = (sctp_init_chunk_t *)skb->data;
965
966 /* Walk the parameters looking for embedded addresses. */
967 sctp_walk_params(params, init, init_hdr.params) {
968
969 /* Note: Ignoring hostname addresses. */
970 af = sctp_get_af_specific(param_type2af(params.p->type));
971 if (!af)
972 continue;
973
974 af->from_addr_param(paddr, params.addr, sh->source, 0);
975
976 asoc = __sctp_lookup_association(net, laddr, paddr, &transport);
977 if (asoc)
978 return asoc;
979 }
980
981 return NULL;
982}
983
984/* ADD-IP, Section 5.2
985 * When an endpoint receives an ASCONF Chunk from the remote peer
986 * special procedures may be needed to identify the association the
987 * ASCONF Chunk is associated with. To properly find the association
988 * the following procedures SHOULD be followed:
989 *
990 * D2) If the association is not found, use the address found in the
991 * Address Parameter TLV combined with the port number found in the
992 * SCTP common header. If found proceed to rule D4.
993 *
994 * D2-ext) If more than one ASCONF Chunks are packed together, use the
995 * address found in the ASCONF Address Parameter TLV of each of the
996 * subsequent ASCONF Chunks. If found, proceed to rule D4.
997 */
998static struct sctp_association *__sctp_rcv_asconf_lookup(
999 struct net *net,
1000 sctp_chunkhdr_t *ch,
1001 const union sctp_addr *laddr,
1002 __be16 peer_port,
1003 struct sctp_transport **transportp)
1004{
1005 sctp_addip_chunk_t *asconf = (struct sctp_addip_chunk *)ch;
1006 struct sctp_af *af;
1007 union sctp_addr_param *param;
1008 union sctp_addr paddr;
1009
1010 /* Skip over the ADDIP header and find the Address parameter */
1011 param = (union sctp_addr_param *)(asconf + 1);
1012
1013 af = sctp_get_af_specific(param_type2af(param->p.type));
1014 if (unlikely(!af))
1015 return NULL;
1016
1017 af->from_addr_param(&paddr, param, peer_port, 0);
1018
1019 return __sctp_lookup_association(net, laddr, &paddr, transportp);
1020}
1021
1022
1023/* SCTP-AUTH, Section 6.3:
1024* If the receiver does not find a STCB for a packet containing an AUTH
1025* chunk as the first chunk and not a COOKIE-ECHO chunk as the second
1026* chunk, it MUST use the chunks after the AUTH chunk to look up an existing
1027* association.
1028*
1029* This means that any chunks that can help us identify the association need
1030* to be looked at to find this association.
1031*/
1032static struct sctp_association *__sctp_rcv_walk_lookup(struct net *net,
1033 struct sk_buff *skb,
1034 const union sctp_addr *laddr,
1035 struct sctp_transport **transportp)
1036{
1037 struct sctp_association *asoc = NULL;
1038 sctp_chunkhdr_t *ch;
1039 int have_auth = 0;
1040 unsigned int chunk_num = 1;
1041 __u8 *ch_end;
1042
1043 /* Walk through the chunks looking for AUTH or ASCONF chunks
1044 * to help us find the association.
1045 */
1046 ch = (sctp_chunkhdr_t *) skb->data;
1047 do {
1048 /* Break out if chunk length is less then minimal. */
1049 if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
1050 break;
1051
1052 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
1053 if (ch_end > skb_tail_pointer(skb))
1054 break;
1055
1056 switch (ch->type) {
1057 case SCTP_CID_AUTH:
1058 have_auth = chunk_num;
1059 break;
1060
1061 case SCTP_CID_COOKIE_ECHO:
1062 /* If a packet arrives containing an AUTH chunk as
1063 * a first chunk, a COOKIE-ECHO chunk as the second
1064 * chunk, and possibly more chunks after them, and
1065 * the receiver does not have an STCB for that
1066 * packet, then authentication is based on
1067 * the contents of the COOKIE- ECHO chunk.
1068 */
1069 if (have_auth == 1 && chunk_num == 2)
1070 return NULL;
1071 break;
1072
1073 case SCTP_CID_ASCONF:
1074 if (have_auth || net->sctp.addip_noauth)
1075 asoc = __sctp_rcv_asconf_lookup(
1076 net, ch, laddr,
1077 sctp_hdr(skb)->source,
1078 transportp);
1079 default:
1080 break;
1081 }
1082
1083 if (asoc)
1084 break;
1085
1086 ch = (sctp_chunkhdr_t *) ch_end;
1087 chunk_num++;
1088 } while (ch_end < skb_tail_pointer(skb));
1089
1090 return asoc;
1091}
1092
1093/*
1094 * There are circumstances when we need to look inside the SCTP packet
1095 * for information to help us find the association. Examples
1096 * include looking inside of INIT/INIT-ACK chunks or after the AUTH
1097 * chunks.
1098 */
1099static struct sctp_association *__sctp_rcv_lookup_harder(struct net *net,
1100 struct sk_buff *skb,
1101 const union sctp_addr *laddr,
1102 struct sctp_transport **transportp)
1103{
1104 sctp_chunkhdr_t *ch;
1105
1106 ch = (sctp_chunkhdr_t *) skb->data;
1107
1108 /* The code below will attempt to walk the chunk and extract
1109 * parameter information. Before we do that, we need to verify
1110 * that the chunk length doesn't cause overflow. Otherwise, we'll
1111 * walk off the end.
1112 */
1113 if (WORD_ROUND(ntohs(ch->length)) > skb->len)
1114 return NULL;
1115
1116 /* If this is INIT/INIT-ACK look inside the chunk too. */
1117 if (ch->type == SCTP_CID_INIT || ch->type == SCTP_CID_INIT_ACK)
1118 return __sctp_rcv_init_lookup(net, skb, laddr, transportp);
1119
1120 return __sctp_rcv_walk_lookup(net, skb, laddr, transportp);
1121}
1122
1123/* Lookup an association for an inbound skb. */
1124static struct sctp_association *__sctp_rcv_lookup(struct net *net,
1125 struct sk_buff *skb,
1126 const union sctp_addr *paddr,
1127 const union sctp_addr *laddr,
1128 struct sctp_transport **transportp)
1129{
1130 struct sctp_association *asoc;
1131
1132 asoc = __sctp_lookup_association(net, laddr, paddr, transportp);
1133
1134 /* Further lookup for INIT/INIT-ACK packets.
1135 * SCTP Implementors Guide, 2.18 Handling of address
1136 * parameters within the INIT or INIT-ACK.
1137 */
1138 if (!asoc)
1139 asoc = __sctp_rcv_lookup_harder(net, skb, laddr, transportp);
1140
1141 return asoc;
1142}
1// SPDX-License-Identifier: GPL-2.0-or-later
2/* SCTP kernel implementation
3 * Copyright (c) 1999-2000 Cisco, Inc.
4 * Copyright (c) 1999-2001 Motorola, Inc.
5 * Copyright (c) 2001-2003 International Business Machines, Corp.
6 * Copyright (c) 2001 Intel Corp.
7 * Copyright (c) 2001 Nokia, Inc.
8 * Copyright (c) 2001 La Monte H.P. Yarroll
9 *
10 * This file is part of the SCTP kernel implementation
11 *
12 * These functions handle all input from the IP layer into SCTP.
13 *
14 * Please send any bug reports or fixes you make to the
15 * email address(es):
16 * lksctp developers <linux-sctp@vger.kernel.org>
17 *
18 * Written or modified by:
19 * La Monte H.P. Yarroll <piggy@acm.org>
20 * Karl Knutson <karl@athena.chicago.il.us>
21 * Xingang Guo <xingang.guo@intel.com>
22 * Jon Grimm <jgrimm@us.ibm.com>
23 * Hui Huang <hui.huang@nokia.com>
24 * Daisy Chang <daisyc@us.ibm.com>
25 * Sridhar Samudrala <sri@us.ibm.com>
26 * Ardelle Fan <ardelle.fan@intel.com>
27 */
28
29#include <linux/types.h>
30#include <linux/list.h> /* For struct list_head */
31#include <linux/socket.h>
32#include <linux/ip.h>
33#include <linux/time.h> /* For struct timeval */
34#include <linux/slab.h>
35#include <net/ip.h>
36#include <net/icmp.h>
37#include <net/snmp.h>
38#include <net/sock.h>
39#include <net/xfrm.h>
40#include <net/sctp/sctp.h>
41#include <net/sctp/sm.h>
42#include <net/sctp/checksum.h>
43#include <net/net_namespace.h>
44#include <linux/rhashtable.h>
45#include <net/sock_reuseport.h>
46
47/* Forward declarations for internal helpers. */
48static int sctp_rcv_ootb(struct sk_buff *);
49static struct sctp_association *__sctp_rcv_lookup(struct net *net,
50 struct sk_buff *skb,
51 const union sctp_addr *paddr,
52 const union sctp_addr *laddr,
53 struct sctp_transport **transportp,
54 int dif, int sdif);
55static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(
56 struct net *net, struct sk_buff *skb,
57 const union sctp_addr *laddr,
58 const union sctp_addr *daddr,
59 int dif, int sdif);
60static struct sctp_association *__sctp_lookup_association(
61 struct net *net,
62 const union sctp_addr *local,
63 const union sctp_addr *peer,
64 struct sctp_transport **pt,
65 int dif, int sdif);
66
67static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb);
68
69
70/* Calculate the SCTP checksum of an SCTP packet. */
71static inline int sctp_rcv_checksum(struct net *net, struct sk_buff *skb)
72{
73 struct sctphdr *sh = sctp_hdr(skb);
74 __le32 cmp = sh->checksum;
75 __le32 val = sctp_compute_cksum(skb, 0);
76
77 if (val != cmp) {
78 /* CRC failure, dump it. */
79 __SCTP_INC_STATS(net, SCTP_MIB_CHECKSUMERRORS);
80 return -1;
81 }
82 return 0;
83}
84
85/*
86 * This is the routine which IP calls when receiving an SCTP packet.
87 */
88int sctp_rcv(struct sk_buff *skb)
89{
90 struct sock *sk;
91 struct sctp_association *asoc;
92 struct sctp_endpoint *ep = NULL;
93 struct sctp_ep_common *rcvr;
94 struct sctp_transport *transport = NULL;
95 struct sctp_chunk *chunk;
96 union sctp_addr src;
97 union sctp_addr dest;
98 int family;
99 struct sctp_af *af;
100 struct net *net = dev_net(skb->dev);
101 bool is_gso = skb_is_gso(skb) && skb_is_gso_sctp(skb);
102 int dif, sdif;
103
104 if (skb->pkt_type != PACKET_HOST)
105 goto discard_it;
106
107 __SCTP_INC_STATS(net, SCTP_MIB_INSCTPPACKS);
108
109 /* If packet is too small to contain a single chunk, let's not
110 * waste time on it anymore.
111 */
112 if (skb->len < sizeof(struct sctphdr) + sizeof(struct sctp_chunkhdr) +
113 skb_transport_offset(skb))
114 goto discard_it;
115
116 /* If the packet is fragmented and we need to do crc checking,
117 * it's better to just linearize it otherwise crc computing
118 * takes longer.
119 */
120 if ((!is_gso && skb_linearize(skb)) ||
121 !pskb_may_pull(skb, sizeof(struct sctphdr)))
122 goto discard_it;
123
124 /* Pull up the IP header. */
125 __skb_pull(skb, skb_transport_offset(skb));
126
127 skb->csum_valid = 0; /* Previous value not applicable */
128 if (skb_csum_unnecessary(skb))
129 __skb_decr_checksum_unnecessary(skb);
130 else if (!sctp_checksum_disable &&
131 !is_gso &&
132 sctp_rcv_checksum(net, skb) < 0)
133 goto discard_it;
134 skb->csum_valid = 1;
135
136 __skb_pull(skb, sizeof(struct sctphdr));
137
138 family = ipver2af(ip_hdr(skb)->version);
139 af = sctp_get_af_specific(family);
140 if (unlikely(!af))
141 goto discard_it;
142 SCTP_INPUT_CB(skb)->af = af;
143
144 /* Initialize local addresses for lookups. */
145 af->from_skb(&src, skb, 1);
146 af->from_skb(&dest, skb, 0);
147 dif = af->skb_iif(skb);
148 sdif = af->skb_sdif(skb);
149
150 /* If the packet is to or from a non-unicast address,
151 * silently discard the packet.
152 *
153 * This is not clearly defined in the RFC except in section
154 * 8.4 - OOTB handling. However, based on the book "Stream Control
155 * Transmission Protocol" 2.1, "It is important to note that the
156 * IP address of an SCTP transport address must be a routable
157 * unicast address. In other words, IP multicast addresses and
158 * IP broadcast addresses cannot be used in an SCTP transport
159 * address."
160 */
161 if (!af->addr_valid(&src, NULL, skb) ||
162 !af->addr_valid(&dest, NULL, skb))
163 goto discard_it;
164
165 asoc = __sctp_rcv_lookup(net, skb, &src, &dest, &transport, dif, sdif);
166
167 if (!asoc)
168 ep = __sctp_rcv_lookup_endpoint(net, skb, &dest, &src, dif, sdif);
169
170 /* Retrieve the common input handling substructure. */
171 rcvr = asoc ? &asoc->base : &ep->base;
172 sk = rcvr->sk;
173
174 /*
175 * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
176 * An SCTP packet is called an "out of the blue" (OOTB)
177 * packet if it is correctly formed, i.e., passed the
178 * receiver's checksum check, but the receiver is not
179 * able to identify the association to which this
180 * packet belongs.
181 */
182 if (!asoc) {
183 if (sctp_rcv_ootb(skb)) {
184 __SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES);
185 goto discard_release;
186 }
187 }
188
189 if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family))
190 goto discard_release;
191 nf_reset_ct(skb);
192
193 if (sk_filter(sk, skb))
194 goto discard_release;
195
196 /* Create an SCTP packet structure. */
197 chunk = sctp_chunkify(skb, asoc, sk, GFP_ATOMIC);
198 if (!chunk)
199 goto discard_release;
200 SCTP_INPUT_CB(skb)->chunk = chunk;
201
202 /* Remember what endpoint is to handle this packet. */
203 chunk->rcvr = rcvr;
204
205 /* Remember the SCTP header. */
206 chunk->sctp_hdr = sctp_hdr(skb);
207
208 /* Set the source and destination addresses of the incoming chunk. */
209 sctp_init_addrs(chunk, &src, &dest);
210
211 /* Remember where we came from. */
212 chunk->transport = transport;
213
214 /* Acquire access to the sock lock. Note: We are safe from other
215 * bottom halves on this lock, but a user may be in the lock too,
216 * so check if it is busy.
217 */
218 bh_lock_sock(sk);
219
220 if (sk != rcvr->sk) {
221 /* Our cached sk is different from the rcvr->sk. This is
222 * because migrate()/accept() may have moved the association
223 * to a new socket and released all the sockets. So now we
224 * are holding a lock on the old socket while the user may
225 * be doing something with the new socket. Switch our veiw
226 * of the current sk.
227 */
228 bh_unlock_sock(sk);
229 sk = rcvr->sk;
230 bh_lock_sock(sk);
231 }
232
233 if (sock_owned_by_user(sk) || !sctp_newsk_ready(sk)) {
234 if (sctp_add_backlog(sk, skb)) {
235 bh_unlock_sock(sk);
236 sctp_chunk_free(chunk);
237 skb = NULL; /* sctp_chunk_free already freed the skb */
238 goto discard_release;
239 }
240 __SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_BACKLOG);
241 } else {
242 __SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_SOFTIRQ);
243 sctp_inq_push(&chunk->rcvr->inqueue, chunk);
244 }
245
246 bh_unlock_sock(sk);
247
248 /* Release the asoc/ep ref we took in the lookup calls. */
249 if (transport)
250 sctp_transport_put(transport);
251 else
252 sctp_endpoint_put(ep);
253
254 return 0;
255
256discard_it:
257 __SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_DISCARDS);
258 kfree_skb(skb);
259 return 0;
260
261discard_release:
262 /* Release the asoc/ep ref we took in the lookup calls. */
263 if (transport)
264 sctp_transport_put(transport);
265 else
266 sctp_endpoint_put(ep);
267
268 goto discard_it;
269}
270
271/* Process the backlog queue of the socket. Every skb on
272 * the backlog holds a ref on an association or endpoint.
273 * We hold this ref throughout the state machine to make
274 * sure that the structure we need is still around.
275 */
276int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
277{
278 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
279 struct sctp_inq *inqueue = &chunk->rcvr->inqueue;
280 struct sctp_transport *t = chunk->transport;
281 struct sctp_ep_common *rcvr = NULL;
282 int backloged = 0;
283
284 rcvr = chunk->rcvr;
285
286 /* If the rcvr is dead then the association or endpoint
287 * has been deleted and we can safely drop the chunk
288 * and refs that we are holding.
289 */
290 if (rcvr->dead) {
291 sctp_chunk_free(chunk);
292 goto done;
293 }
294
295 if (unlikely(rcvr->sk != sk)) {
296 /* In this case, the association moved from one socket to
297 * another. We are currently sitting on the backlog of the
298 * old socket, so we need to move.
299 * However, since we are here in the process context we
300 * need to take make sure that the user doesn't own
301 * the new socket when we process the packet.
302 * If the new socket is user-owned, queue the chunk to the
303 * backlog of the new socket without dropping any refs.
304 * Otherwise, we can safely push the chunk on the inqueue.
305 */
306
307 sk = rcvr->sk;
308 local_bh_disable();
309 bh_lock_sock(sk);
310
311 if (sock_owned_by_user(sk) || !sctp_newsk_ready(sk)) {
312 if (sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf)))
313 sctp_chunk_free(chunk);
314 else
315 backloged = 1;
316 } else
317 sctp_inq_push(inqueue, chunk);
318
319 bh_unlock_sock(sk);
320 local_bh_enable();
321
322 /* If the chunk was backloged again, don't drop refs */
323 if (backloged)
324 return 0;
325 } else {
326 if (!sctp_newsk_ready(sk)) {
327 if (!sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf)))
328 return 0;
329 sctp_chunk_free(chunk);
330 } else {
331 sctp_inq_push(inqueue, chunk);
332 }
333 }
334
335done:
336 /* Release the refs we took in sctp_add_backlog */
337 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
338 sctp_transport_put(t);
339 else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
340 sctp_endpoint_put(sctp_ep(rcvr));
341 else
342 BUG();
343
344 return 0;
345}
346
347static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb)
348{
349 struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
350 struct sctp_transport *t = chunk->transport;
351 struct sctp_ep_common *rcvr = chunk->rcvr;
352 int ret;
353
354 ret = sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf));
355 if (!ret) {
356 /* Hold the assoc/ep while hanging on the backlog queue.
357 * This way, we know structures we need will not disappear
358 * from us
359 */
360 if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
361 sctp_transport_hold(t);
362 else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
363 sctp_endpoint_hold(sctp_ep(rcvr));
364 else
365 BUG();
366 }
367 return ret;
368
369}
370
371/* Handle icmp frag needed error. */
372void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc,
373 struct sctp_transport *t, __u32 pmtu)
374{
375 if (!t ||
376 (t->pathmtu <= pmtu &&
377 t->pl.probe_size + sctp_transport_pl_hlen(t) <= pmtu))
378 return;
379
380 if (sock_owned_by_user(sk)) {
381 atomic_set(&t->mtu_info, pmtu);
382 asoc->pmtu_pending = 1;
383 t->pmtu_pending = 1;
384 return;
385 }
386
387 if (!(t->param_flags & SPP_PMTUD_ENABLE))
388 /* We can't allow retransmitting in such case, as the
389 * retransmission would be sized just as before, and thus we
390 * would get another icmp, and retransmit again.
391 */
392 return;
393
394 /* Update transports view of the MTU. Return if no update was needed.
395 * If an update wasn't needed/possible, it also doesn't make sense to
396 * try to retransmit now.
397 */
398 if (!sctp_transport_update_pmtu(t, pmtu))
399 return;
400
401 /* Update association pmtu. */
402 sctp_assoc_sync_pmtu(asoc);
403
404 /* Retransmit with the new pmtu setting. */
405 sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD);
406}
407
408void sctp_icmp_redirect(struct sock *sk, struct sctp_transport *t,
409 struct sk_buff *skb)
410{
411 struct dst_entry *dst;
412
413 if (sock_owned_by_user(sk) || !t)
414 return;
415 dst = sctp_transport_dst_check(t);
416 if (dst)
417 dst->ops->redirect(dst, sk, skb);
418}
419
420/*
421 * SCTP Implementer's Guide, 2.37 ICMP handling procedures
422 *
423 * ICMP8) If the ICMP code is a "Unrecognized next header type encountered"
424 * or a "Protocol Unreachable" treat this message as an abort
425 * with the T bit set.
426 *
427 * This function sends an event to the state machine, which will abort the
428 * association.
429 *
430 */
431void sctp_icmp_proto_unreachable(struct sock *sk,
432 struct sctp_association *asoc,
433 struct sctp_transport *t)
434{
435 if (sock_owned_by_user(sk)) {
436 if (timer_pending(&t->proto_unreach_timer))
437 return;
438 else {
439 if (!mod_timer(&t->proto_unreach_timer,
440 jiffies + (HZ/20)))
441 sctp_transport_hold(t);
442 }
443 } else {
444 struct net *net = sock_net(sk);
445
446 pr_debug("%s: unrecognized next header type "
447 "encountered!\n", __func__);
448
449 if (del_timer(&t->proto_unreach_timer))
450 sctp_transport_put(t);
451
452 sctp_do_sm(net, SCTP_EVENT_T_OTHER,
453 SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH),
454 asoc->state, asoc->ep, asoc, t,
455 GFP_ATOMIC);
456 }
457}
458
459/* Common lookup code for icmp/icmpv6 error handler. */
460struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *skb,
461 struct sctphdr *sctphdr,
462 struct sctp_association **app,
463 struct sctp_transport **tpp)
464{
465 struct sctp_init_chunk *chunkhdr, _chunkhdr;
466 union sctp_addr saddr;
467 union sctp_addr daddr;
468 struct sctp_af *af;
469 struct sock *sk = NULL;
470 struct sctp_association *asoc;
471 struct sctp_transport *transport = NULL;
472 __u32 vtag = ntohl(sctphdr->vtag);
473 int sdif = inet_sdif(skb);
474 int dif = inet_iif(skb);
475
476 *app = NULL; *tpp = NULL;
477
478 af = sctp_get_af_specific(family);
479 if (unlikely(!af)) {
480 return NULL;
481 }
482
483 /* Initialize local addresses for lookups. */
484 af->from_skb(&saddr, skb, 1);
485 af->from_skb(&daddr, skb, 0);
486
487 /* Look for an association that matches the incoming ICMP error
488 * packet.
489 */
490 asoc = __sctp_lookup_association(net, &saddr, &daddr, &transport, dif, sdif);
491 if (!asoc)
492 return NULL;
493
494 sk = asoc->base.sk;
495
496 /* RFC 4960, Appendix C. ICMP Handling
497 *
498 * ICMP6) An implementation MUST validate that the Verification Tag
499 * contained in the ICMP message matches the Verification Tag of
500 * the peer. If the Verification Tag is not 0 and does NOT
501 * match, discard the ICMP message. If it is 0 and the ICMP
502 * message contains enough bytes to verify that the chunk type is
503 * an INIT chunk and that the Initiate Tag matches the tag of the
504 * peer, continue with ICMP7. If the ICMP message is too short
505 * or the chunk type or the Initiate Tag does not match, silently
506 * discard the packet.
507 */
508 if (vtag == 0) {
509 /* chunk header + first 4 octects of init header */
510 chunkhdr = skb_header_pointer(skb, skb_transport_offset(skb) +
511 sizeof(struct sctphdr),
512 sizeof(struct sctp_chunkhdr) +
513 sizeof(__be32), &_chunkhdr);
514 if (!chunkhdr ||
515 chunkhdr->chunk_hdr.type != SCTP_CID_INIT ||
516 ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag)
517 goto out;
518
519 } else if (vtag != asoc->c.peer_vtag) {
520 goto out;
521 }
522
523 bh_lock_sock(sk);
524
525 /* If too many ICMPs get dropped on busy
526 * servers this needs to be solved differently.
527 */
528 if (sock_owned_by_user(sk))
529 __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS);
530
531 *app = asoc;
532 *tpp = transport;
533 return sk;
534
535out:
536 sctp_transport_put(transport);
537 return NULL;
538}
539
540/* Common cleanup code for icmp/icmpv6 error handler. */
541void sctp_err_finish(struct sock *sk, struct sctp_transport *t)
542 __releases(&((__sk)->sk_lock.slock))
543{
544 bh_unlock_sock(sk);
545 sctp_transport_put(t);
546}
547
548static void sctp_v4_err_handle(struct sctp_transport *t, struct sk_buff *skb,
549 __u8 type, __u8 code, __u32 info)
550{
551 struct sctp_association *asoc = t->asoc;
552 struct sock *sk = asoc->base.sk;
553 int err = 0;
554
555 switch (type) {
556 case ICMP_PARAMETERPROB:
557 err = EPROTO;
558 break;
559 case ICMP_DEST_UNREACH:
560 if (code > NR_ICMP_UNREACH)
561 return;
562 if (code == ICMP_FRAG_NEEDED) {
563 sctp_icmp_frag_needed(sk, asoc, t, SCTP_TRUNC4(info));
564 return;
565 }
566 if (code == ICMP_PROT_UNREACH) {
567 sctp_icmp_proto_unreachable(sk, asoc, t);
568 return;
569 }
570 err = icmp_err_convert[code].errno;
571 break;
572 case ICMP_TIME_EXCEEDED:
573 if (code == ICMP_EXC_FRAGTIME)
574 return;
575
576 err = EHOSTUNREACH;
577 break;
578 case ICMP_REDIRECT:
579 sctp_icmp_redirect(sk, t, skb);
580 return;
581 default:
582 return;
583 }
584 if (!sock_owned_by_user(sk) && inet_test_bit(RECVERR, sk)) {
585 sk->sk_err = err;
586 sk_error_report(sk);
587 } else { /* Only an error on timeout */
588 WRITE_ONCE(sk->sk_err_soft, err);
589 }
590}
591
592/*
593 * This routine is called by the ICMP module when it gets some
594 * sort of error condition. If err < 0 then the socket should
595 * be closed and the error returned to the user. If err > 0
596 * it's just the icmp type << 8 | icmp code. After adjustment
597 * header points to the first 8 bytes of the sctp header. We need
598 * to find the appropriate port.
599 *
600 * The locking strategy used here is very "optimistic". When
601 * someone else accesses the socket the ICMP is just dropped
602 * and for some paths there is no check at all.
603 * A more general error queue to queue errors for later handling
604 * is probably better.
605 *
606 */
607int sctp_v4_err(struct sk_buff *skb, __u32 info)
608{
609 const struct iphdr *iph = (const struct iphdr *)skb->data;
610 const int type = icmp_hdr(skb)->type;
611 const int code = icmp_hdr(skb)->code;
612 struct net *net = dev_net(skb->dev);
613 struct sctp_transport *transport;
614 struct sctp_association *asoc;
615 __u16 saveip, savesctp;
616 struct sock *sk;
617
618 /* Fix up skb to look at the embedded net header. */
619 saveip = skb->network_header;
620 savesctp = skb->transport_header;
621 skb_reset_network_header(skb);
622 skb_set_transport_header(skb, iph->ihl * 4);
623 sk = sctp_err_lookup(net, AF_INET, skb, sctp_hdr(skb), &asoc, &transport);
624 /* Put back, the original values. */
625 skb->network_header = saveip;
626 skb->transport_header = savesctp;
627 if (!sk) {
628 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
629 return -ENOENT;
630 }
631
632 sctp_v4_err_handle(transport, skb, type, code, info);
633 sctp_err_finish(sk, transport);
634
635 return 0;
636}
637
638int sctp_udp_v4_err(struct sock *sk, struct sk_buff *skb)
639{
640 struct net *net = dev_net(skb->dev);
641 struct sctp_association *asoc;
642 struct sctp_transport *t;
643 struct icmphdr *hdr;
644 __u32 info = 0;
645
646 skb->transport_header += sizeof(struct udphdr);
647 sk = sctp_err_lookup(net, AF_INET, skb, sctp_hdr(skb), &asoc, &t);
648 if (!sk) {
649 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
650 return -ENOENT;
651 }
652
653 skb->transport_header -= sizeof(struct udphdr);
654 hdr = (struct icmphdr *)(skb_network_header(skb) - sizeof(struct icmphdr));
655 if (hdr->type == ICMP_REDIRECT) {
656 /* can't be handled without outer iphdr known, leave it to udp_err */
657 sctp_err_finish(sk, t);
658 return 0;
659 }
660 if (hdr->type == ICMP_DEST_UNREACH && hdr->code == ICMP_FRAG_NEEDED)
661 info = ntohs(hdr->un.frag.mtu);
662 sctp_v4_err_handle(t, skb, hdr->type, hdr->code, info);
663
664 sctp_err_finish(sk, t);
665 return 1;
666}
667
668/*
669 * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
670 *
671 * This function scans all the chunks in the OOTB packet to determine if
672 * the packet should be discarded right away. If a response might be needed
673 * for this packet, or, if further processing is possible, the packet will
674 * be queued to a proper inqueue for the next phase of handling.
675 *
676 * Output:
677 * Return 0 - If further processing is needed.
678 * Return 1 - If the packet can be discarded right away.
679 */
680static int sctp_rcv_ootb(struct sk_buff *skb)
681{
682 struct sctp_chunkhdr *ch, _ch;
683 int ch_end, offset = 0;
684
685 /* Scan through all the chunks in the packet. */
686 do {
687 /* Make sure we have at least the header there */
688 if (offset + sizeof(_ch) > skb->len)
689 break;
690
691 ch = skb_header_pointer(skb, offset, sizeof(*ch), &_ch);
692
693 /* Break out if chunk length is less then minimal. */
694 if (!ch || ntohs(ch->length) < sizeof(_ch))
695 break;
696
697 ch_end = offset + SCTP_PAD4(ntohs(ch->length));
698 if (ch_end > skb->len)
699 break;
700
701 /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the
702 * receiver MUST silently discard the OOTB packet and take no
703 * further action.
704 */
705 if (SCTP_CID_ABORT == ch->type)
706 goto discard;
707
708 /* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE
709 * chunk, the receiver should silently discard the packet
710 * and take no further action.
711 */
712 if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type)
713 goto discard;
714
715 /* RFC 4460, 2.11.2
716 * This will discard packets with INIT chunk bundled as
717 * subsequent chunks in the packet. When INIT is first,
718 * the normal INIT processing will discard the chunk.
719 */
720 if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data)
721 goto discard;
722
723 offset = ch_end;
724 } while (ch_end < skb->len);
725
726 return 0;
727
728discard:
729 return 1;
730}
731
732/* Insert endpoint into the hash table. */
733static int __sctp_hash_endpoint(struct sctp_endpoint *ep)
734{
735 struct sock *sk = ep->base.sk;
736 struct net *net = sock_net(sk);
737 struct sctp_hashbucket *head;
738
739 ep->hashent = sctp_ep_hashfn(net, ep->base.bind_addr.port);
740 head = &sctp_ep_hashtable[ep->hashent];
741
742 if (sk->sk_reuseport) {
743 bool any = sctp_is_ep_boundall(sk);
744 struct sctp_endpoint *ep2;
745 struct list_head *list;
746 int cnt = 0, err = 1;
747
748 list_for_each(list, &ep->base.bind_addr.address_list)
749 cnt++;
750
751 sctp_for_each_hentry(ep2, &head->chain) {
752 struct sock *sk2 = ep2->base.sk;
753
754 if (!net_eq(sock_net(sk2), net) || sk2 == sk ||
755 !uid_eq(sock_i_uid(sk2), sock_i_uid(sk)) ||
756 !sk2->sk_reuseport)
757 continue;
758
759 err = sctp_bind_addrs_check(sctp_sk(sk2),
760 sctp_sk(sk), cnt);
761 if (!err) {
762 err = reuseport_add_sock(sk, sk2, any);
763 if (err)
764 return err;
765 break;
766 } else if (err < 0) {
767 return err;
768 }
769 }
770
771 if (err) {
772 err = reuseport_alloc(sk, any);
773 if (err)
774 return err;
775 }
776 }
777
778 write_lock(&head->lock);
779 hlist_add_head(&ep->node, &head->chain);
780 write_unlock(&head->lock);
781 return 0;
782}
783
784/* Add an endpoint to the hash. Local BH-safe. */
785int sctp_hash_endpoint(struct sctp_endpoint *ep)
786{
787 int err;
788
789 local_bh_disable();
790 err = __sctp_hash_endpoint(ep);
791 local_bh_enable();
792
793 return err;
794}
795
796/* Remove endpoint from the hash table. */
797static void __sctp_unhash_endpoint(struct sctp_endpoint *ep)
798{
799 struct sock *sk = ep->base.sk;
800 struct sctp_hashbucket *head;
801
802 ep->hashent = sctp_ep_hashfn(sock_net(sk), ep->base.bind_addr.port);
803
804 head = &sctp_ep_hashtable[ep->hashent];
805
806 if (rcu_access_pointer(sk->sk_reuseport_cb))
807 reuseport_detach_sock(sk);
808
809 write_lock(&head->lock);
810 hlist_del_init(&ep->node);
811 write_unlock(&head->lock);
812}
813
814/* Remove endpoint from the hash. Local BH-safe. */
815void sctp_unhash_endpoint(struct sctp_endpoint *ep)
816{
817 local_bh_disable();
818 __sctp_unhash_endpoint(ep);
819 local_bh_enable();
820}
821
822static inline __u32 sctp_hashfn(const struct net *net, __be16 lport,
823 const union sctp_addr *paddr, __u32 seed)
824{
825 __u32 addr;
826
827 if (paddr->sa.sa_family == AF_INET6)
828 addr = jhash(&paddr->v6.sin6_addr, 16, seed);
829 else
830 addr = (__force __u32)paddr->v4.sin_addr.s_addr;
831
832 return jhash_3words(addr, ((__force __u32)paddr->v4.sin_port) << 16 |
833 (__force __u32)lport, net_hash_mix(net), seed);
834}
835
836/* Look up an endpoint. */
837static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(
838 struct net *net, struct sk_buff *skb,
839 const union sctp_addr *laddr,
840 const union sctp_addr *paddr,
841 int dif, int sdif)
842{
843 struct sctp_hashbucket *head;
844 struct sctp_endpoint *ep;
845 struct sock *sk;
846 __be16 lport;
847 int hash;
848
849 lport = laddr->v4.sin_port;
850 hash = sctp_ep_hashfn(net, ntohs(lport));
851 head = &sctp_ep_hashtable[hash];
852 read_lock(&head->lock);
853 sctp_for_each_hentry(ep, &head->chain) {
854 if (sctp_endpoint_is_match(ep, net, laddr, dif, sdif))
855 goto hit;
856 }
857
858 ep = sctp_sk(net->sctp.ctl_sock)->ep;
859
860hit:
861 sk = ep->base.sk;
862 if (sk->sk_reuseport) {
863 __u32 phash = sctp_hashfn(net, lport, paddr, 0);
864
865 sk = reuseport_select_sock(sk, phash, skb,
866 sizeof(struct sctphdr));
867 if (sk)
868 ep = sctp_sk(sk)->ep;
869 }
870 sctp_endpoint_hold(ep);
871 read_unlock(&head->lock);
872 return ep;
873}
874
875/* rhashtable for transport */
876struct sctp_hash_cmp_arg {
877 const union sctp_addr *paddr;
878 const struct net *net;
879 __be16 lport;
880};
881
882static inline int sctp_hash_cmp(struct rhashtable_compare_arg *arg,
883 const void *ptr)
884{
885 struct sctp_transport *t = (struct sctp_transport *)ptr;
886 const struct sctp_hash_cmp_arg *x = arg->key;
887 int err = 1;
888
889 if (!sctp_cmp_addr_exact(&t->ipaddr, x->paddr))
890 return err;
891 if (!sctp_transport_hold(t))
892 return err;
893
894 if (!net_eq(t->asoc->base.net, x->net))
895 goto out;
896 if (x->lport != htons(t->asoc->base.bind_addr.port))
897 goto out;
898
899 err = 0;
900out:
901 sctp_transport_put(t);
902 return err;
903}
904
905static inline __u32 sctp_hash_obj(const void *data, u32 len, u32 seed)
906{
907 const struct sctp_transport *t = data;
908
909 return sctp_hashfn(t->asoc->base.net,
910 htons(t->asoc->base.bind_addr.port),
911 &t->ipaddr, seed);
912}
913
914static inline __u32 sctp_hash_key(const void *data, u32 len, u32 seed)
915{
916 const struct sctp_hash_cmp_arg *x = data;
917
918 return sctp_hashfn(x->net, x->lport, x->paddr, seed);
919}
920
921static const struct rhashtable_params sctp_hash_params = {
922 .head_offset = offsetof(struct sctp_transport, node),
923 .hashfn = sctp_hash_key,
924 .obj_hashfn = sctp_hash_obj,
925 .obj_cmpfn = sctp_hash_cmp,
926 .automatic_shrinking = true,
927};
928
929int sctp_transport_hashtable_init(void)
930{
931 return rhltable_init(&sctp_transport_hashtable, &sctp_hash_params);
932}
933
934void sctp_transport_hashtable_destroy(void)
935{
936 rhltable_destroy(&sctp_transport_hashtable);
937}
938
939int sctp_hash_transport(struct sctp_transport *t)
940{
941 struct sctp_transport *transport;
942 struct rhlist_head *tmp, *list;
943 struct sctp_hash_cmp_arg arg;
944 int err;
945
946 if (t->asoc->temp)
947 return 0;
948
949 arg.net = t->asoc->base.net;
950 arg.paddr = &t->ipaddr;
951 arg.lport = htons(t->asoc->base.bind_addr.port);
952
953 rcu_read_lock();
954 list = rhltable_lookup(&sctp_transport_hashtable, &arg,
955 sctp_hash_params);
956
957 rhl_for_each_entry_rcu(transport, tmp, list, node)
958 if (transport->asoc->ep == t->asoc->ep) {
959 rcu_read_unlock();
960 return -EEXIST;
961 }
962 rcu_read_unlock();
963
964 err = rhltable_insert_key(&sctp_transport_hashtable, &arg,
965 &t->node, sctp_hash_params);
966 if (err)
967 pr_err_once("insert transport fail, errno %d\n", err);
968
969 return err;
970}
971
972void sctp_unhash_transport(struct sctp_transport *t)
973{
974 if (t->asoc->temp)
975 return;
976
977 rhltable_remove(&sctp_transport_hashtable, &t->node,
978 sctp_hash_params);
979}
980
981bool sctp_sk_bound_dev_eq(struct net *net, int bound_dev_if, int dif, int sdif)
982{
983 bool l3mdev_accept = true;
984
985#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
986 l3mdev_accept = !!READ_ONCE(net->sctp.l3mdev_accept);
987#endif
988 return inet_bound_dev_eq(l3mdev_accept, bound_dev_if, dif, sdif);
989}
990
991/* return a transport with holding it */
992struct sctp_transport *sctp_addrs_lookup_transport(
993 struct net *net,
994 const union sctp_addr *laddr,
995 const union sctp_addr *paddr,
996 int dif, int sdif)
997{
998 struct rhlist_head *tmp, *list;
999 struct sctp_transport *t;
1000 int bound_dev_if;
1001 struct sctp_hash_cmp_arg arg = {
1002 .paddr = paddr,
1003 .net = net,
1004 .lport = laddr->v4.sin_port,
1005 };
1006
1007 list = rhltable_lookup(&sctp_transport_hashtable, &arg,
1008 sctp_hash_params);
1009
1010 rhl_for_each_entry_rcu(t, tmp, list, node) {
1011 if (!sctp_transport_hold(t))
1012 continue;
1013
1014 bound_dev_if = READ_ONCE(t->asoc->base.sk->sk_bound_dev_if);
1015 if (sctp_sk_bound_dev_eq(net, bound_dev_if, dif, sdif) &&
1016 sctp_bind_addr_match(&t->asoc->base.bind_addr,
1017 laddr, sctp_sk(t->asoc->base.sk)))
1018 return t;
1019 sctp_transport_put(t);
1020 }
1021
1022 return NULL;
1023}
1024
1025/* return a transport without holding it, as it's only used under sock lock */
1026struct sctp_transport *sctp_epaddr_lookup_transport(
1027 const struct sctp_endpoint *ep,
1028 const union sctp_addr *paddr)
1029{
1030 struct rhlist_head *tmp, *list;
1031 struct sctp_transport *t;
1032 struct sctp_hash_cmp_arg arg = {
1033 .paddr = paddr,
1034 .net = ep->base.net,
1035 .lport = htons(ep->base.bind_addr.port),
1036 };
1037
1038 list = rhltable_lookup(&sctp_transport_hashtable, &arg,
1039 sctp_hash_params);
1040
1041 rhl_for_each_entry_rcu(t, tmp, list, node)
1042 if (ep == t->asoc->ep)
1043 return t;
1044
1045 return NULL;
1046}
1047
1048/* Look up an association. */
1049static struct sctp_association *__sctp_lookup_association(
1050 struct net *net,
1051 const union sctp_addr *local,
1052 const union sctp_addr *peer,
1053 struct sctp_transport **pt,
1054 int dif, int sdif)
1055{
1056 struct sctp_transport *t;
1057 struct sctp_association *asoc = NULL;
1058
1059 t = sctp_addrs_lookup_transport(net, local, peer, dif, sdif);
1060 if (!t)
1061 goto out;
1062
1063 asoc = t->asoc;
1064 *pt = t;
1065
1066out:
1067 return asoc;
1068}
1069
1070/* Look up an association. protected by RCU read lock */
1071static
1072struct sctp_association *sctp_lookup_association(struct net *net,
1073 const union sctp_addr *laddr,
1074 const union sctp_addr *paddr,
1075 struct sctp_transport **transportp,
1076 int dif, int sdif)
1077{
1078 struct sctp_association *asoc;
1079
1080 rcu_read_lock();
1081 asoc = __sctp_lookup_association(net, laddr, paddr, transportp, dif, sdif);
1082 rcu_read_unlock();
1083
1084 return asoc;
1085}
1086
1087/* Is there an association matching the given local and peer addresses? */
1088bool sctp_has_association(struct net *net,
1089 const union sctp_addr *laddr,
1090 const union sctp_addr *paddr,
1091 int dif, int sdif)
1092{
1093 struct sctp_transport *transport;
1094
1095 if (sctp_lookup_association(net, laddr, paddr, &transport, dif, sdif)) {
1096 sctp_transport_put(transport);
1097 return true;
1098 }
1099
1100 return false;
1101}
1102
1103/*
1104 * SCTP Implementors Guide, 2.18 Handling of address
1105 * parameters within the INIT or INIT-ACK.
1106 *
1107 * D) When searching for a matching TCB upon reception of an INIT
1108 * or INIT-ACK chunk the receiver SHOULD use not only the
1109 * source address of the packet (containing the INIT or
1110 * INIT-ACK) but the receiver SHOULD also use all valid
1111 * address parameters contained within the chunk.
1112 *
1113 * 2.18.3 Solution description
1114 *
1115 * This new text clearly specifies to an implementor the need
1116 * to look within the INIT or INIT-ACK. Any implementation that
1117 * does not do this, may not be able to establish associations
1118 * in certain circumstances.
1119 *
1120 */
1121static struct sctp_association *__sctp_rcv_init_lookup(struct net *net,
1122 struct sk_buff *skb,
1123 const union sctp_addr *laddr, struct sctp_transport **transportp,
1124 int dif, int sdif)
1125{
1126 struct sctp_association *asoc;
1127 union sctp_addr addr;
1128 union sctp_addr *paddr = &addr;
1129 struct sctphdr *sh = sctp_hdr(skb);
1130 union sctp_params params;
1131 struct sctp_init_chunk *init;
1132 struct sctp_af *af;
1133
1134 /*
1135 * This code will NOT touch anything inside the chunk--it is
1136 * strictly READ-ONLY.
1137 *
1138 * RFC 2960 3 SCTP packet Format
1139 *
1140 * Multiple chunks can be bundled into one SCTP packet up to
1141 * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN
1142 * COMPLETE chunks. These chunks MUST NOT be bundled with any
1143 * other chunk in a packet. See Section 6.10 for more details
1144 * on chunk bundling.
1145 */
1146
1147 /* Find the start of the TLVs and the end of the chunk. This is
1148 * the region we search for address parameters.
1149 */
1150 init = (struct sctp_init_chunk *)skb->data;
1151
1152 /* Walk the parameters looking for embedded addresses. */
1153 sctp_walk_params(params, init) {
1154
1155 /* Note: Ignoring hostname addresses. */
1156 af = sctp_get_af_specific(param_type2af(params.p->type));
1157 if (!af)
1158 continue;
1159
1160 if (!af->from_addr_param(paddr, params.addr, sh->source, 0))
1161 continue;
1162
1163 asoc = __sctp_lookup_association(net, laddr, paddr, transportp, dif, sdif);
1164 if (asoc)
1165 return asoc;
1166 }
1167
1168 return NULL;
1169}
1170
1171/* ADD-IP, Section 5.2
1172 * When an endpoint receives an ASCONF Chunk from the remote peer
1173 * special procedures may be needed to identify the association the
1174 * ASCONF Chunk is associated with. To properly find the association
1175 * the following procedures SHOULD be followed:
1176 *
1177 * D2) If the association is not found, use the address found in the
1178 * Address Parameter TLV combined with the port number found in the
1179 * SCTP common header. If found proceed to rule D4.
1180 *
1181 * D2-ext) If more than one ASCONF Chunks are packed together, use the
1182 * address found in the ASCONF Address Parameter TLV of each of the
1183 * subsequent ASCONF Chunks. If found, proceed to rule D4.
1184 */
1185static struct sctp_association *__sctp_rcv_asconf_lookup(
1186 struct net *net,
1187 struct sctp_chunkhdr *ch,
1188 const union sctp_addr *laddr,
1189 __be16 peer_port,
1190 struct sctp_transport **transportp,
1191 int dif, int sdif)
1192{
1193 struct sctp_addip_chunk *asconf = (struct sctp_addip_chunk *)ch;
1194 struct sctp_af *af;
1195 union sctp_addr_param *param;
1196 union sctp_addr paddr;
1197
1198 if (ntohs(ch->length) < sizeof(*asconf) + sizeof(struct sctp_paramhdr))
1199 return NULL;
1200
1201 /* Skip over the ADDIP header and find the Address parameter */
1202 param = (union sctp_addr_param *)(asconf + 1);
1203
1204 af = sctp_get_af_specific(param_type2af(param->p.type));
1205 if (unlikely(!af))
1206 return NULL;
1207
1208 if (!af->from_addr_param(&paddr, param, peer_port, 0))
1209 return NULL;
1210
1211 return __sctp_lookup_association(net, laddr, &paddr, transportp, dif, sdif);
1212}
1213
1214
1215/* SCTP-AUTH, Section 6.3:
1216* If the receiver does not find a STCB for a packet containing an AUTH
1217* chunk as the first chunk and not a COOKIE-ECHO chunk as the second
1218* chunk, it MUST use the chunks after the AUTH chunk to look up an existing
1219* association.
1220*
1221* This means that any chunks that can help us identify the association need
1222* to be looked at to find this association.
1223*/
1224static struct sctp_association *__sctp_rcv_walk_lookup(struct net *net,
1225 struct sk_buff *skb,
1226 const union sctp_addr *laddr,
1227 struct sctp_transport **transportp,
1228 int dif, int sdif)
1229{
1230 struct sctp_association *asoc = NULL;
1231 struct sctp_chunkhdr *ch;
1232 int have_auth = 0;
1233 unsigned int chunk_num = 1;
1234 __u8 *ch_end;
1235
1236 /* Walk through the chunks looking for AUTH or ASCONF chunks
1237 * to help us find the association.
1238 */
1239 ch = (struct sctp_chunkhdr *)skb->data;
1240 do {
1241 /* Break out if chunk length is less then minimal. */
1242 if (ntohs(ch->length) < sizeof(*ch))
1243 break;
1244
1245 ch_end = ((__u8 *)ch) + SCTP_PAD4(ntohs(ch->length));
1246 if (ch_end > skb_tail_pointer(skb))
1247 break;
1248
1249 switch (ch->type) {
1250 case SCTP_CID_AUTH:
1251 have_auth = chunk_num;
1252 break;
1253
1254 case SCTP_CID_COOKIE_ECHO:
1255 /* If a packet arrives containing an AUTH chunk as
1256 * a first chunk, a COOKIE-ECHO chunk as the second
1257 * chunk, and possibly more chunks after them, and
1258 * the receiver does not have an STCB for that
1259 * packet, then authentication is based on
1260 * the contents of the COOKIE- ECHO chunk.
1261 */
1262 if (have_auth == 1 && chunk_num == 2)
1263 return NULL;
1264 break;
1265
1266 case SCTP_CID_ASCONF:
1267 if (have_auth || net->sctp.addip_noauth)
1268 asoc = __sctp_rcv_asconf_lookup(
1269 net, ch, laddr,
1270 sctp_hdr(skb)->source,
1271 transportp, dif, sdif);
1272 break;
1273 default:
1274 break;
1275 }
1276
1277 if (asoc)
1278 break;
1279
1280 ch = (struct sctp_chunkhdr *)ch_end;
1281 chunk_num++;
1282 } while (ch_end + sizeof(*ch) < skb_tail_pointer(skb));
1283
1284 return asoc;
1285}
1286
1287/*
1288 * There are circumstances when we need to look inside the SCTP packet
1289 * for information to help us find the association. Examples
1290 * include looking inside of INIT/INIT-ACK chunks or after the AUTH
1291 * chunks.
1292 */
1293static struct sctp_association *__sctp_rcv_lookup_harder(struct net *net,
1294 struct sk_buff *skb,
1295 const union sctp_addr *laddr,
1296 struct sctp_transport **transportp,
1297 int dif, int sdif)
1298{
1299 struct sctp_chunkhdr *ch;
1300
1301 /* We do not allow GSO frames here as we need to linearize and
1302 * then cannot guarantee frame boundaries. This shouldn't be an
1303 * issue as packets hitting this are mostly INIT or INIT-ACK and
1304 * those cannot be on GSO-style anyway.
1305 */
1306 if (skb_is_gso(skb) && skb_is_gso_sctp(skb))
1307 return NULL;
1308
1309 ch = (struct sctp_chunkhdr *)skb->data;
1310
1311 /* The code below will attempt to walk the chunk and extract
1312 * parameter information. Before we do that, we need to verify
1313 * that the chunk length doesn't cause overflow. Otherwise, we'll
1314 * walk off the end.
1315 */
1316 if (SCTP_PAD4(ntohs(ch->length)) > skb->len)
1317 return NULL;
1318
1319 /* If this is INIT/INIT-ACK look inside the chunk too. */
1320 if (ch->type == SCTP_CID_INIT || ch->type == SCTP_CID_INIT_ACK)
1321 return __sctp_rcv_init_lookup(net, skb, laddr, transportp, dif, sdif);
1322
1323 return __sctp_rcv_walk_lookup(net, skb, laddr, transportp, dif, sdif);
1324}
1325
1326/* Lookup an association for an inbound skb. */
1327static struct sctp_association *__sctp_rcv_lookup(struct net *net,
1328 struct sk_buff *skb,
1329 const union sctp_addr *paddr,
1330 const union sctp_addr *laddr,
1331 struct sctp_transport **transportp,
1332 int dif, int sdif)
1333{
1334 struct sctp_association *asoc;
1335
1336 asoc = __sctp_lookup_association(net, laddr, paddr, transportp, dif, sdif);
1337 if (asoc)
1338 goto out;
1339
1340 /* Further lookup for INIT/INIT-ACK packets.
1341 * SCTP Implementors Guide, 2.18 Handling of address
1342 * parameters within the INIT or INIT-ACK.
1343 */
1344 asoc = __sctp_rcv_lookup_harder(net, skb, laddr, transportp, dif, sdif);
1345 if (asoc)
1346 goto out;
1347
1348 if (paddr->sa.sa_family == AF_INET)
1349 pr_debug("sctp: asoc not found for src:%pI4:%d dst:%pI4:%d\n",
1350 &laddr->v4.sin_addr, ntohs(laddr->v4.sin_port),
1351 &paddr->v4.sin_addr, ntohs(paddr->v4.sin_port));
1352 else
1353 pr_debug("sctp: asoc not found for src:%pI6:%d dst:%pI6:%d\n",
1354 &laddr->v6.sin6_addr, ntohs(laddr->v6.sin6_port),
1355 &paddr->v6.sin6_addr, ntohs(paddr->v6.sin6_port));
1356
1357out:
1358 return asoc;
1359}