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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. */ | |
61 | static int sctp_rcv_ootb(struct sk_buff *); | |
62 | static 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); | |
67 | static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(struct net *net, | |
68 | const union sctp_addr *laddr); | |
69 | static 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 | ||
75 | static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb); | |
76 | ||
77 | ||
78 | /* Calculate the SCTP checksum of an SCTP packet. */ | |
79 | static 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(net, SCTP_MIB_CHECKSUMERRORS); | |
88 | return -1; | |
89 | } | |
90 | return 0; | |
91 | } | |
92 | ||
93 | /* | |
94 | * This is the routine which IP calls when receiving an SCTP packet. | |
95 | */ | |
96 | int sctp_rcv(struct sk_buff *skb) | |
97 | { | |
98 | struct sock *sk; | |
99 | struct sctp_association *asoc; | |
100 | struct sctp_endpoint *ep = NULL; | |
101 | struct sctp_ep_common *rcvr; | |
102 | struct sctp_transport *transport = NULL; | |
103 | struct sctp_chunk *chunk; | |
104 | union sctp_addr src; | |
105 | union sctp_addr dest; | |
106 | int family; | |
107 | struct sctp_af *af; | |
108 | struct net *net = dev_net(skb->dev); | |
109 | ||
110 | if (skb->pkt_type != PACKET_HOST) | |
111 | goto discard_it; | |
112 | ||
113 | __SCTP_INC_STATS(net, SCTP_MIB_INSCTPPACKS); | |
114 | ||
115 | /* If packet is too small to contain a single chunk, let's not | |
116 | * waste time on it anymore. | |
117 | */ | |
118 | if (skb->len < sizeof(struct sctphdr) + sizeof(struct sctp_chunkhdr) + | |
119 | skb_transport_offset(skb)) | |
120 | goto discard_it; | |
121 | ||
122 | /* If the packet is fragmented and we need to do crc checking, | |
123 | * it's better to just linearize it otherwise crc computing | |
124 | * takes longer. | |
125 | */ | |
126 | if ((!(skb_shinfo(skb)->gso_type & SKB_GSO_SCTP) && | |
127 | skb_linearize(skb)) || | |
128 | !pskb_may_pull(skb, sizeof(struct sctphdr))) | |
129 | goto discard_it; | |
130 | ||
131 | /* Pull up the IP header. */ | |
132 | __skb_pull(skb, skb_transport_offset(skb)); | |
133 | ||
134 | skb->csum_valid = 0; /* Previous value not applicable */ | |
135 | if (skb_csum_unnecessary(skb)) | |
136 | __skb_decr_checksum_unnecessary(skb); | |
137 | else if (!sctp_checksum_disable && | |
138 | !(skb_shinfo(skb)->gso_type & SKB_GSO_SCTP) && | |
139 | sctp_rcv_checksum(net, skb) < 0) | |
140 | goto discard_it; | |
141 | skb->csum_valid = 1; | |
142 | ||
143 | __skb_pull(skb, sizeof(struct sctphdr)); | |
144 | ||
145 | family = ipver2af(ip_hdr(skb)->version); | |
146 | af = sctp_get_af_specific(family); | |
147 | if (unlikely(!af)) | |
148 | goto discard_it; | |
149 | SCTP_INPUT_CB(skb)->af = af; | |
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 (transport) { | |
185 | sctp_transport_put(transport); | |
186 | asoc = NULL; | |
187 | transport = NULL; | |
188 | } else { | |
189 | sctp_endpoint_put(ep); | |
190 | ep = NULL; | |
191 | } | |
192 | sk = net->sctp.ctl_sock; | |
193 | ep = sctp_sk(sk)->ep; | |
194 | sctp_endpoint_hold(ep); | |
195 | rcvr = &ep->base; | |
196 | } | |
197 | ||
198 | /* | |
199 | * RFC 2960, 8.4 - Handle "Out of the blue" Packets. | |
200 | * An SCTP packet is called an "out of the blue" (OOTB) | |
201 | * packet if it is correctly formed, i.e., passed the | |
202 | * receiver's checksum check, but the receiver is not | |
203 | * able to identify the association to which this | |
204 | * packet belongs. | |
205 | */ | |
206 | if (!asoc) { | |
207 | if (sctp_rcv_ootb(skb)) { | |
208 | __SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES); | |
209 | goto discard_release; | |
210 | } | |
211 | } | |
212 | ||
213 | if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family)) | |
214 | goto discard_release; | |
215 | nf_reset(skb); | |
216 | ||
217 | if (sk_filter(sk, skb)) | |
218 | goto discard_release; | |
219 | ||
220 | /* Create an SCTP packet structure. */ | |
221 | chunk = sctp_chunkify(skb, asoc, sk, GFP_ATOMIC); | |
222 | if (!chunk) | |
223 | goto discard_release; | |
224 | SCTP_INPUT_CB(skb)->chunk = chunk; | |
225 | ||
226 | /* Remember what endpoint is to handle this packet. */ | |
227 | chunk->rcvr = rcvr; | |
228 | ||
229 | /* Remember the SCTP header. */ | |
230 | chunk->sctp_hdr = sctp_hdr(skb); | |
231 | ||
232 | /* Set the source and destination addresses of the incoming chunk. */ | |
233 | sctp_init_addrs(chunk, &src, &dest); | |
234 | ||
235 | /* Remember where we came from. */ | |
236 | chunk->transport = transport; | |
237 | ||
238 | /* Acquire access to the sock lock. Note: We are safe from other | |
239 | * bottom halves on this lock, but a user may be in the lock too, | |
240 | * so check if it is busy. | |
241 | */ | |
242 | bh_lock_sock(sk); | |
243 | ||
244 | if (sk != rcvr->sk) { | |
245 | /* Our cached sk is different from the rcvr->sk. This is | |
246 | * because migrate()/accept() may have moved the association | |
247 | * to a new socket and released all the sockets. So now we | |
248 | * are holding a lock on the old socket while the user may | |
249 | * be doing something with the new socket. Switch our veiw | |
250 | * of the current sk. | |
251 | */ | |
252 | bh_unlock_sock(sk); | |
253 | sk = rcvr->sk; | |
254 | bh_lock_sock(sk); | |
255 | } | |
256 | ||
257 | if (sock_owned_by_user(sk)) { | |
258 | if (sctp_add_backlog(sk, skb)) { | |
259 | bh_unlock_sock(sk); | |
260 | sctp_chunk_free(chunk); | |
261 | skb = NULL; /* sctp_chunk_free already freed the skb */ | |
262 | goto discard_release; | |
263 | } | |
264 | __SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_BACKLOG); | |
265 | } else { | |
266 | __SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_SOFTIRQ); | |
267 | sctp_inq_push(&chunk->rcvr->inqueue, chunk); | |
268 | } | |
269 | ||
270 | bh_unlock_sock(sk); | |
271 | ||
272 | /* Release the asoc/ep ref we took in the lookup calls. */ | |
273 | if (transport) | |
274 | sctp_transport_put(transport); | |
275 | else | |
276 | sctp_endpoint_put(ep); | |
277 | ||
278 | return 0; | |
279 | ||
280 | discard_it: | |
281 | __SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_DISCARDS); | |
282 | kfree_skb(skb); | |
283 | return 0; | |
284 | ||
285 | discard_release: | |
286 | /* Release the asoc/ep ref we took in the lookup calls. */ | |
287 | if (transport) | |
288 | sctp_transport_put(transport); | |
289 | else | |
290 | sctp_endpoint_put(ep); | |
291 | ||
292 | goto discard_it; | |
293 | } | |
294 | ||
295 | /* Process the backlog queue of the socket. Every skb on | |
296 | * the backlog holds a ref on an association or endpoint. | |
297 | * We hold this ref throughout the state machine to make | |
298 | * sure that the structure we need is still around. | |
299 | */ | |
300 | int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb) | |
301 | { | |
302 | struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk; | |
303 | struct sctp_inq *inqueue = &chunk->rcvr->inqueue; | |
304 | struct sctp_transport *t = chunk->transport; | |
305 | struct sctp_ep_common *rcvr = NULL; | |
306 | int backloged = 0; | |
307 | ||
308 | rcvr = chunk->rcvr; | |
309 | ||
310 | /* If the rcvr is dead then the association or endpoint | |
311 | * has been deleted and we can safely drop the chunk | |
312 | * and refs that we are holding. | |
313 | */ | |
314 | if (rcvr->dead) { | |
315 | sctp_chunk_free(chunk); | |
316 | goto done; | |
317 | } | |
318 | ||
319 | if (unlikely(rcvr->sk != sk)) { | |
320 | /* In this case, the association moved from one socket to | |
321 | * another. We are currently sitting on the backlog of the | |
322 | * old socket, so we need to move. | |
323 | * However, since we are here in the process context we | |
324 | * need to take make sure that the user doesn't own | |
325 | * the new socket when we process the packet. | |
326 | * If the new socket is user-owned, queue the chunk to the | |
327 | * backlog of the new socket without dropping any refs. | |
328 | * Otherwise, we can safely push the chunk on the inqueue. | |
329 | */ | |
330 | ||
331 | sk = rcvr->sk; | |
332 | local_bh_disable(); | |
333 | bh_lock_sock(sk); | |
334 | ||
335 | if (sock_owned_by_user(sk)) { | |
336 | if (sk_add_backlog(sk, skb, sk->sk_rcvbuf)) | |
337 | sctp_chunk_free(chunk); | |
338 | else | |
339 | backloged = 1; | |
340 | } else | |
341 | sctp_inq_push(inqueue, chunk); | |
342 | ||
343 | bh_unlock_sock(sk); | |
344 | local_bh_enable(); | |
345 | ||
346 | /* If the chunk was backloged again, don't drop refs */ | |
347 | if (backloged) | |
348 | return 0; | |
349 | } else { | |
350 | sctp_inq_push(inqueue, chunk); | |
351 | } | |
352 | ||
353 | done: | |
354 | /* Release the refs we took in sctp_add_backlog */ | |
355 | if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type) | |
356 | sctp_transport_put(t); | |
357 | else if (SCTP_EP_TYPE_SOCKET == rcvr->type) | |
358 | sctp_endpoint_put(sctp_ep(rcvr)); | |
359 | else | |
360 | BUG(); | |
361 | ||
362 | return 0; | |
363 | } | |
364 | ||
365 | static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb) | |
366 | { | |
367 | struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk; | |
368 | struct sctp_transport *t = chunk->transport; | |
369 | struct sctp_ep_common *rcvr = chunk->rcvr; | |
370 | int ret; | |
371 | ||
372 | ret = sk_add_backlog(sk, skb, sk->sk_rcvbuf); | |
373 | if (!ret) { | |
374 | /* Hold the assoc/ep while hanging on the backlog queue. | |
375 | * This way, we know structures we need will not disappear | |
376 | * from us | |
377 | */ | |
378 | if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type) | |
379 | sctp_transport_hold(t); | |
380 | else if (SCTP_EP_TYPE_SOCKET == rcvr->type) | |
381 | sctp_endpoint_hold(sctp_ep(rcvr)); | |
382 | else | |
383 | BUG(); | |
384 | } | |
385 | return ret; | |
386 | ||
387 | } | |
388 | ||
389 | /* Handle icmp frag needed error. */ | |
390 | void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc, | |
391 | struct sctp_transport *t, __u32 pmtu) | |
392 | { | |
393 | if (!t || (t->pathmtu <= pmtu)) | |
394 | return; | |
395 | ||
396 | if (sock_owned_by_user(sk)) { | |
397 | asoc->pmtu_pending = 1; | |
398 | t->pmtu_pending = 1; | |
399 | return; | |
400 | } | |
401 | ||
402 | if (t->param_flags & SPP_PMTUD_ENABLE) { | |
403 | /* Update transports view of the MTU */ | |
404 | sctp_transport_update_pmtu(t, pmtu); | |
405 | ||
406 | /* Update association pmtu. */ | |
407 | sctp_assoc_sync_pmtu(asoc); | |
408 | } | |
409 | ||
410 | /* Retransmit with the new pmtu setting. | |
411 | * Normally, if PMTU discovery is disabled, an ICMP Fragmentation | |
412 | * Needed will never be sent, but if a message was sent before | |
413 | * PMTU discovery was disabled that was larger than the PMTU, it | |
414 | * would not be fragmented, so it must be re-transmitted fragmented. | |
415 | */ | |
416 | sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD); | |
417 | } | |
418 | ||
419 | void sctp_icmp_redirect(struct sock *sk, struct sctp_transport *t, | |
420 | struct sk_buff *skb) | |
421 | { | |
422 | struct dst_entry *dst; | |
423 | ||
424 | if (!t) | |
425 | return; | |
426 | dst = sctp_transport_dst_check(t); | |
427 | if (dst) | |
428 | dst->ops->redirect(dst, sk, skb); | |
429 | } | |
430 | ||
431 | /* | |
432 | * SCTP Implementer's Guide, 2.37 ICMP handling procedures | |
433 | * | |
434 | * ICMP8) If the ICMP code is a "Unrecognized next header type encountered" | |
435 | * or a "Protocol Unreachable" treat this message as an abort | |
436 | * with the T bit set. | |
437 | * | |
438 | * This function sends an event to the state machine, which will abort the | |
439 | * association. | |
440 | * | |
441 | */ | |
442 | void sctp_icmp_proto_unreachable(struct sock *sk, | |
443 | struct sctp_association *asoc, | |
444 | struct sctp_transport *t) | |
445 | { | |
446 | if (sock_owned_by_user(sk)) { | |
447 | if (timer_pending(&t->proto_unreach_timer)) | |
448 | return; | |
449 | else { | |
450 | if (!mod_timer(&t->proto_unreach_timer, | |
451 | jiffies + (HZ/20))) | |
452 | sctp_association_hold(asoc); | |
453 | } | |
454 | } else { | |
455 | struct net *net = sock_net(sk); | |
456 | ||
457 | pr_debug("%s: unrecognized next header type " | |
458 | "encountered!\n", __func__); | |
459 | ||
460 | if (del_timer(&t->proto_unreach_timer)) | |
461 | sctp_association_put(asoc); | |
462 | ||
463 | sctp_do_sm(net, SCTP_EVENT_T_OTHER, | |
464 | SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH), | |
465 | asoc->state, asoc->ep, asoc, t, | |
466 | GFP_ATOMIC); | |
467 | } | |
468 | } | |
469 | ||
470 | /* Common lookup code for icmp/icmpv6 error handler. */ | |
471 | struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *skb, | |
472 | struct sctphdr *sctphdr, | |
473 | struct sctp_association **app, | |
474 | struct sctp_transport **tpp) | |
475 | { | |
476 | union sctp_addr saddr; | |
477 | union sctp_addr daddr; | |
478 | struct sctp_af *af; | |
479 | struct sock *sk = NULL; | |
480 | struct sctp_association *asoc; | |
481 | struct sctp_transport *transport = NULL; | |
482 | struct sctp_init_chunk *chunkhdr; | |
483 | __u32 vtag = ntohl(sctphdr->vtag); | |
484 | int len = skb->len - ((void *)sctphdr - (void *)skb->data); | |
485 | ||
486 | *app = NULL; *tpp = NULL; | |
487 | ||
488 | af = sctp_get_af_specific(family); | |
489 | if (unlikely(!af)) { | |
490 | return NULL; | |
491 | } | |
492 | ||
493 | /* Initialize local addresses for lookups. */ | |
494 | af->from_skb(&saddr, skb, 1); | |
495 | af->from_skb(&daddr, skb, 0); | |
496 | ||
497 | /* Look for an association that matches the incoming ICMP error | |
498 | * packet. | |
499 | */ | |
500 | asoc = __sctp_lookup_association(net, &saddr, &daddr, &transport); | |
501 | if (!asoc) | |
502 | return NULL; | |
503 | ||
504 | sk = asoc->base.sk; | |
505 | ||
506 | /* RFC 4960, Appendix C. ICMP Handling | |
507 | * | |
508 | * ICMP6) An implementation MUST validate that the Verification Tag | |
509 | * contained in the ICMP message matches the Verification Tag of | |
510 | * the peer. If the Verification Tag is not 0 and does NOT | |
511 | * match, discard the ICMP message. If it is 0 and the ICMP | |
512 | * message contains enough bytes to verify that the chunk type is | |
513 | * an INIT chunk and that the Initiate Tag matches the tag of the | |
514 | * peer, continue with ICMP7. If the ICMP message is too short | |
515 | * or the chunk type or the Initiate Tag does not match, silently | |
516 | * discard the packet. | |
517 | */ | |
518 | if (vtag == 0) { | |
519 | chunkhdr = (void *)sctphdr + sizeof(struct sctphdr); | |
520 | if (len < sizeof(struct sctphdr) + sizeof(sctp_chunkhdr_t) | |
521 | + sizeof(__be32) || | |
522 | chunkhdr->chunk_hdr.type != SCTP_CID_INIT || | |
523 | ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag) { | |
524 | goto out; | |
525 | } | |
526 | } else if (vtag != asoc->c.peer_vtag) { | |
527 | goto out; | |
528 | } | |
529 | ||
530 | bh_lock_sock(sk); | |
531 | ||
532 | /* If too many ICMPs get dropped on busy | |
533 | * servers this needs to be solved differently. | |
534 | */ | |
535 | if (sock_owned_by_user(sk)) | |
536 | __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS); | |
537 | ||
538 | *app = asoc; | |
539 | *tpp = transport; | |
540 | return sk; | |
541 | ||
542 | out: | |
543 | sctp_transport_put(transport); | |
544 | return NULL; | |
545 | } | |
546 | ||
547 | /* Common cleanup code for icmp/icmpv6 error handler. */ | |
548 | void sctp_err_finish(struct sock *sk, struct sctp_transport *t) | |
549 | { | |
550 | bh_unlock_sock(sk); | |
551 | sctp_transport_put(t); | |
552 | } | |
553 | ||
554 | /* | |
555 | * This routine is called by the ICMP module when it gets some | |
556 | * sort of error condition. If err < 0 then the socket should | |
557 | * be closed and the error returned to the user. If err > 0 | |
558 | * it's just the icmp type << 8 | icmp code. After adjustment | |
559 | * header points to the first 8 bytes of the sctp header. We need | |
560 | * to find the appropriate port. | |
561 | * | |
562 | * The locking strategy used here is very "optimistic". When | |
563 | * someone else accesses the socket the ICMP is just dropped | |
564 | * and for some paths there is no check at all. | |
565 | * A more general error queue to queue errors for later handling | |
566 | * is probably better. | |
567 | * | |
568 | */ | |
569 | void sctp_v4_err(struct sk_buff *skb, __u32 info) | |
570 | { | |
571 | const struct iphdr *iph = (const struct iphdr *)skb->data; | |
572 | const int ihlen = iph->ihl * 4; | |
573 | const int type = icmp_hdr(skb)->type; | |
574 | const int code = icmp_hdr(skb)->code; | |
575 | struct sock *sk; | |
576 | struct sctp_association *asoc = NULL; | |
577 | struct sctp_transport *transport; | |
578 | struct inet_sock *inet; | |
579 | __u16 saveip, savesctp; | |
580 | int err; | |
581 | struct net *net = dev_net(skb->dev); | |
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(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, | |
611 | SCTP_TRUNC4(info)); | |
612 | goto out_unlock; | |
613 | } else { | |
614 | if (ICMP_PROT_UNREACH == code) { | |
615 | sctp_icmp_proto_unreachable(sk, asoc, | |
616 | transport); | |
617 | goto out_unlock; | |
618 | } | |
619 | } | |
620 | err = icmp_err_convert[code].errno; | |
621 | break; | |
622 | case ICMP_TIME_EXCEEDED: | |
623 | /* Ignore any time exceeded errors due to fragment reassembly | |
624 | * timeouts. | |
625 | */ | |
626 | if (ICMP_EXC_FRAGTIME == code) | |
627 | goto out_unlock; | |
628 | ||
629 | err = EHOSTUNREACH; | |
630 | break; | |
631 | case ICMP_REDIRECT: | |
632 | sctp_icmp_redirect(sk, transport, skb); | |
633 | /* Fall through to out_unlock. */ | |
634 | default: | |
635 | goto out_unlock; | |
636 | } | |
637 | ||
638 | inet = inet_sk(sk); | |
639 | if (!sock_owned_by_user(sk) && inet->recverr) { | |
640 | sk->sk_err = err; | |
641 | sk->sk_error_report(sk); | |
642 | } else { /* Only an error on timeout */ | |
643 | sk->sk_err_soft = err; | |
644 | } | |
645 | ||
646 | out_unlock: | |
647 | sctp_err_finish(sk, transport); | |
648 | } | |
649 | ||
650 | /* | |
651 | * RFC 2960, 8.4 - Handle "Out of the blue" Packets. | |
652 | * | |
653 | * This function scans all the chunks in the OOTB packet to determine if | |
654 | * the packet should be discarded right away. If a response might be needed | |
655 | * for this packet, or, if further processing is possible, the packet will | |
656 | * be queued to a proper inqueue for the next phase of handling. | |
657 | * | |
658 | * Output: | |
659 | * Return 0 - If further processing is needed. | |
660 | * Return 1 - If the packet can be discarded right away. | |
661 | */ | |
662 | static int sctp_rcv_ootb(struct sk_buff *skb) | |
663 | { | |
664 | sctp_chunkhdr_t *ch, _ch; | |
665 | int ch_end, offset = 0; | |
666 | ||
667 | /* Scan through all the chunks in the packet. */ | |
668 | do { | |
669 | /* Make sure we have at least the header there */ | |
670 | if (offset + sizeof(sctp_chunkhdr_t) > skb->len) | |
671 | break; | |
672 | ||
673 | ch = skb_header_pointer(skb, offset, sizeof(*ch), &_ch); | |
674 | ||
675 | /* Break out if chunk length is less then minimal. */ | |
676 | if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t)) | |
677 | break; | |
678 | ||
679 | ch_end = offset + SCTP_PAD4(ntohs(ch->length)); | |
680 | if (ch_end > skb->len) | |
681 | break; | |
682 | ||
683 | /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the | |
684 | * receiver MUST silently discard the OOTB packet and take no | |
685 | * further action. | |
686 | */ | |
687 | if (SCTP_CID_ABORT == ch->type) | |
688 | goto discard; | |
689 | ||
690 | /* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE | |
691 | * chunk, the receiver should silently discard the packet | |
692 | * and take no further action. | |
693 | */ | |
694 | if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type) | |
695 | goto discard; | |
696 | ||
697 | /* RFC 4460, 2.11.2 | |
698 | * This will discard packets with INIT chunk bundled as | |
699 | * subsequent chunks in the packet. When INIT is first, | |
700 | * the normal INIT processing will discard the chunk. | |
701 | */ | |
702 | if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data) | |
703 | goto discard; | |
704 | ||
705 | offset = ch_end; | |
706 | } while (ch_end < skb->len); | |
707 | ||
708 | return 0; | |
709 | ||
710 | discard: | |
711 | return 1; | |
712 | } | |
713 | ||
714 | /* Insert endpoint into the hash table. */ | |
715 | static void __sctp_hash_endpoint(struct sctp_endpoint *ep) | |
716 | { | |
717 | struct net *net = sock_net(ep->base.sk); | |
718 | struct sctp_ep_common *epb; | |
719 | struct sctp_hashbucket *head; | |
720 | ||
721 | epb = &ep->base; | |
722 | ||
723 | epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port); | |
724 | head = &sctp_ep_hashtable[epb->hashent]; | |
725 | ||
726 | write_lock(&head->lock); | |
727 | hlist_add_head(&epb->node, &head->chain); | |
728 | write_unlock(&head->lock); | |
729 | } | |
730 | ||
731 | /* Add an endpoint to the hash. Local BH-safe. */ | |
732 | void sctp_hash_endpoint(struct sctp_endpoint *ep) | |
733 | { | |
734 | local_bh_disable(); | |
735 | __sctp_hash_endpoint(ep); | |
736 | local_bh_enable(); | |
737 | } | |
738 | ||
739 | /* Remove endpoint from the hash table. */ | |
740 | static void __sctp_unhash_endpoint(struct sctp_endpoint *ep) | |
741 | { | |
742 | struct net *net = sock_net(ep->base.sk); | |
743 | struct sctp_hashbucket *head; | |
744 | struct sctp_ep_common *epb; | |
745 | ||
746 | epb = &ep->base; | |
747 | ||
748 | epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port); | |
749 | ||
750 | head = &sctp_ep_hashtable[epb->hashent]; | |
751 | ||
752 | write_lock(&head->lock); | |
753 | hlist_del_init(&epb->node); | |
754 | write_unlock(&head->lock); | |
755 | } | |
756 | ||
757 | /* Remove endpoint from the hash. Local BH-safe. */ | |
758 | void sctp_unhash_endpoint(struct sctp_endpoint *ep) | |
759 | { | |
760 | local_bh_disable(); | |
761 | __sctp_unhash_endpoint(ep); | |
762 | local_bh_enable(); | |
763 | } | |
764 | ||
765 | /* Look up an endpoint. */ | |
766 | static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(struct net *net, | |
767 | const union sctp_addr *laddr) | |
768 | { | |
769 | struct sctp_hashbucket *head; | |
770 | struct sctp_ep_common *epb; | |
771 | struct sctp_endpoint *ep; | |
772 | int hash; | |
773 | ||
774 | hash = sctp_ep_hashfn(net, ntohs(laddr->v4.sin_port)); | |
775 | head = &sctp_ep_hashtable[hash]; | |
776 | read_lock(&head->lock); | |
777 | sctp_for_each_hentry(epb, &head->chain) { | |
778 | ep = sctp_ep(epb); | |
779 | if (sctp_endpoint_is_match(ep, net, laddr)) | |
780 | goto hit; | |
781 | } | |
782 | ||
783 | ep = sctp_sk(net->sctp.ctl_sock)->ep; | |
784 | ||
785 | hit: | |
786 | sctp_endpoint_hold(ep); | |
787 | read_unlock(&head->lock); | |
788 | return ep; | |
789 | } | |
790 | ||
791 | /* rhashtable for transport */ | |
792 | struct sctp_hash_cmp_arg { | |
793 | const union sctp_addr *paddr; | |
794 | const struct net *net; | |
795 | u16 lport; | |
796 | }; | |
797 | ||
798 | static inline int sctp_hash_cmp(struct rhashtable_compare_arg *arg, | |
799 | const void *ptr) | |
800 | { | |
801 | struct sctp_transport *t = (struct sctp_transport *)ptr; | |
802 | const struct sctp_hash_cmp_arg *x = arg->key; | |
803 | int err = 1; | |
804 | ||
805 | if (!sctp_cmp_addr_exact(&t->ipaddr, x->paddr)) | |
806 | return err; | |
807 | if (!sctp_transport_hold(t)) | |
808 | return err; | |
809 | ||
810 | if (!net_eq(sock_net(t->asoc->base.sk), x->net)) | |
811 | goto out; | |
812 | if (x->lport != htons(t->asoc->base.bind_addr.port)) | |
813 | goto out; | |
814 | ||
815 | err = 0; | |
816 | out: | |
817 | sctp_transport_put(t); | |
818 | return err; | |
819 | } | |
820 | ||
821 | static inline u32 sctp_hash_obj(const void *data, u32 len, u32 seed) | |
822 | { | |
823 | const struct sctp_transport *t = data; | |
824 | const union sctp_addr *paddr = &t->ipaddr; | |
825 | const struct net *net = sock_net(t->asoc->base.sk); | |
826 | u16 lport = htons(t->asoc->base.bind_addr.port); | |
827 | u32 addr; | |
828 | ||
829 | if (paddr->sa.sa_family == AF_INET6) | |
830 | addr = jhash(&paddr->v6.sin6_addr, 16, seed); | |
831 | else | |
832 | addr = paddr->v4.sin_addr.s_addr; | |
833 | ||
834 | return jhash_3words(addr, ((__u32)paddr->v4.sin_port) << 16 | | |
835 | (__force __u32)lport, net_hash_mix(net), seed); | |
836 | } | |
837 | ||
838 | static inline u32 sctp_hash_key(const void *data, u32 len, u32 seed) | |
839 | { | |
840 | const struct sctp_hash_cmp_arg *x = data; | |
841 | const union sctp_addr *paddr = x->paddr; | |
842 | const struct net *net = x->net; | |
843 | u16 lport = x->lport; | |
844 | u32 addr; | |
845 | ||
846 | if (paddr->sa.sa_family == AF_INET6) | |
847 | addr = jhash(&paddr->v6.sin6_addr, 16, seed); | |
848 | else | |
849 | addr = paddr->v4.sin_addr.s_addr; | |
850 | ||
851 | return jhash_3words(addr, ((__u32)paddr->v4.sin_port) << 16 | | |
852 | (__force __u32)lport, net_hash_mix(net), seed); | |
853 | } | |
854 | ||
855 | static const struct rhashtable_params sctp_hash_params = { | |
856 | .head_offset = offsetof(struct sctp_transport, node), | |
857 | .hashfn = sctp_hash_key, | |
858 | .obj_hashfn = sctp_hash_obj, | |
859 | .obj_cmpfn = sctp_hash_cmp, | |
860 | .automatic_shrinking = true, | |
861 | }; | |
862 | ||
863 | int sctp_transport_hashtable_init(void) | |
864 | { | |
865 | return rhltable_init(&sctp_transport_hashtable, &sctp_hash_params); | |
866 | } | |
867 | ||
868 | void sctp_transport_hashtable_destroy(void) | |
869 | { | |
870 | rhltable_destroy(&sctp_transport_hashtable); | |
871 | } | |
872 | ||
873 | int sctp_hash_transport(struct sctp_transport *t) | |
874 | { | |
875 | struct sctp_transport *transport; | |
876 | struct rhlist_head *tmp, *list; | |
877 | struct sctp_hash_cmp_arg arg; | |
878 | int err; | |
879 | ||
880 | if (t->asoc->temp) | |
881 | return 0; | |
882 | ||
883 | arg.net = sock_net(t->asoc->base.sk); | |
884 | arg.paddr = &t->ipaddr; | |
885 | arg.lport = htons(t->asoc->base.bind_addr.port); | |
886 | ||
887 | rcu_read_lock(); | |
888 | list = rhltable_lookup(&sctp_transport_hashtable, &arg, | |
889 | sctp_hash_params); | |
890 | ||
891 | rhl_for_each_entry_rcu(transport, tmp, list, node) | |
892 | if (transport->asoc->ep == t->asoc->ep) { | |
893 | rcu_read_unlock(); | |
894 | err = -EEXIST; | |
895 | goto out; | |
896 | } | |
897 | rcu_read_unlock(); | |
898 | ||
899 | err = rhltable_insert_key(&sctp_transport_hashtable, &arg, | |
900 | &t->node, sctp_hash_params); | |
901 | ||
902 | out: | |
903 | if (err) | |
904 | pr_err_once("insert transport fail, errno %d\n", err); | |
905 | ||
906 | return err; | |
907 | } | |
908 | ||
909 | void sctp_unhash_transport(struct sctp_transport *t) | |
910 | { | |
911 | if (t->asoc->temp) | |
912 | return; | |
913 | ||
914 | rhltable_remove(&sctp_transport_hashtable, &t->node, | |
915 | sctp_hash_params); | |
916 | } | |
917 | ||
918 | /* return a transport with holding it */ | |
919 | struct sctp_transport *sctp_addrs_lookup_transport( | |
920 | struct net *net, | |
921 | const union sctp_addr *laddr, | |
922 | const union sctp_addr *paddr) | |
923 | { | |
924 | struct rhlist_head *tmp, *list; | |
925 | struct sctp_transport *t; | |
926 | struct sctp_hash_cmp_arg arg = { | |
927 | .paddr = paddr, | |
928 | .net = net, | |
929 | .lport = laddr->v4.sin_port, | |
930 | }; | |
931 | ||
932 | list = rhltable_lookup(&sctp_transport_hashtable, &arg, | |
933 | sctp_hash_params); | |
934 | ||
935 | rhl_for_each_entry_rcu(t, tmp, list, node) { | |
936 | if (!sctp_transport_hold(t)) | |
937 | continue; | |
938 | ||
939 | if (sctp_bind_addr_match(&t->asoc->base.bind_addr, | |
940 | laddr, sctp_sk(t->asoc->base.sk))) | |
941 | return t; | |
942 | sctp_transport_put(t); | |
943 | } | |
944 | ||
945 | return NULL; | |
946 | } | |
947 | ||
948 | /* return a transport without holding it, as it's only used under sock lock */ | |
949 | struct sctp_transport *sctp_epaddr_lookup_transport( | |
950 | const struct sctp_endpoint *ep, | |
951 | const union sctp_addr *paddr) | |
952 | { | |
953 | struct net *net = sock_net(ep->base.sk); | |
954 | struct rhlist_head *tmp, *list; | |
955 | struct sctp_transport *t; | |
956 | struct sctp_hash_cmp_arg arg = { | |
957 | .paddr = paddr, | |
958 | .net = net, | |
959 | .lport = htons(ep->base.bind_addr.port), | |
960 | }; | |
961 | ||
962 | list = rhltable_lookup(&sctp_transport_hashtable, &arg, | |
963 | sctp_hash_params); | |
964 | ||
965 | rhl_for_each_entry_rcu(t, tmp, list, node) | |
966 | if (ep == t->asoc->ep) | |
967 | return t; | |
968 | ||
969 | return NULL; | |
970 | } | |
971 | ||
972 | /* Look up an association. */ | |
973 | static struct sctp_association *__sctp_lookup_association( | |
974 | struct net *net, | |
975 | const union sctp_addr *local, | |
976 | const union sctp_addr *peer, | |
977 | struct sctp_transport **pt) | |
978 | { | |
979 | struct sctp_transport *t; | |
980 | struct sctp_association *asoc = NULL; | |
981 | ||
982 | t = sctp_addrs_lookup_transport(net, local, peer); | |
983 | if (!t) | |
984 | goto out; | |
985 | ||
986 | asoc = t->asoc; | |
987 | *pt = t; | |
988 | ||
989 | out: | |
990 | return asoc; | |
991 | } | |
992 | ||
993 | /* Look up an association. protected by RCU read lock */ | |
994 | static | |
995 | struct sctp_association *sctp_lookup_association(struct net *net, | |
996 | const union sctp_addr *laddr, | |
997 | const union sctp_addr *paddr, | |
998 | struct sctp_transport **transportp) | |
999 | { | |
1000 | struct sctp_association *asoc; | |
1001 | ||
1002 | rcu_read_lock(); | |
1003 | asoc = __sctp_lookup_association(net, laddr, paddr, transportp); | |
1004 | rcu_read_unlock(); | |
1005 | ||
1006 | return asoc; | |
1007 | } | |
1008 | ||
1009 | /* Is there an association matching the given local and peer addresses? */ | |
1010 | int sctp_has_association(struct net *net, | |
1011 | const union sctp_addr *laddr, | |
1012 | const union sctp_addr *paddr) | |
1013 | { | |
1014 | struct sctp_association *asoc; | |
1015 | struct sctp_transport *transport; | |
1016 | ||
1017 | if ((asoc = sctp_lookup_association(net, laddr, paddr, &transport))) { | |
1018 | sctp_transport_put(transport); | |
1019 | return 1; | |
1020 | } | |
1021 | ||
1022 | return 0; | |
1023 | } | |
1024 | ||
1025 | /* | |
1026 | * SCTP Implementors Guide, 2.18 Handling of address | |
1027 | * parameters within the INIT or INIT-ACK. | |
1028 | * | |
1029 | * D) When searching for a matching TCB upon reception of an INIT | |
1030 | * or INIT-ACK chunk the receiver SHOULD use not only the | |
1031 | * source address of the packet (containing the INIT or | |
1032 | * INIT-ACK) but the receiver SHOULD also use all valid | |
1033 | * address parameters contained within the chunk. | |
1034 | * | |
1035 | * 2.18.3 Solution description | |
1036 | * | |
1037 | * This new text clearly specifies to an implementor the need | |
1038 | * to look within the INIT or INIT-ACK. Any implementation that | |
1039 | * does not do this, may not be able to establish associations | |
1040 | * in certain circumstances. | |
1041 | * | |
1042 | */ | |
1043 | static struct sctp_association *__sctp_rcv_init_lookup(struct net *net, | |
1044 | struct sk_buff *skb, | |
1045 | const union sctp_addr *laddr, struct sctp_transport **transportp) | |
1046 | { | |
1047 | struct sctp_association *asoc; | |
1048 | union sctp_addr addr; | |
1049 | union sctp_addr *paddr = &addr; | |
1050 | struct sctphdr *sh = sctp_hdr(skb); | |
1051 | union sctp_params params; | |
1052 | sctp_init_chunk_t *init; | |
1053 | struct sctp_af *af; | |
1054 | ||
1055 | /* | |
1056 | * This code will NOT touch anything inside the chunk--it is | |
1057 | * strictly READ-ONLY. | |
1058 | * | |
1059 | * RFC 2960 3 SCTP packet Format | |
1060 | * | |
1061 | * Multiple chunks can be bundled into one SCTP packet up to | |
1062 | * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN | |
1063 | * COMPLETE chunks. These chunks MUST NOT be bundled with any | |
1064 | * other chunk in a packet. See Section 6.10 for more details | |
1065 | * on chunk bundling. | |
1066 | */ | |
1067 | ||
1068 | /* Find the start of the TLVs and the end of the chunk. This is | |
1069 | * the region we search for address parameters. | |
1070 | */ | |
1071 | init = (sctp_init_chunk_t *)skb->data; | |
1072 | ||
1073 | /* Walk the parameters looking for embedded addresses. */ | |
1074 | sctp_walk_params(params, init, init_hdr.params) { | |
1075 | ||
1076 | /* Note: Ignoring hostname addresses. */ | |
1077 | af = sctp_get_af_specific(param_type2af(params.p->type)); | |
1078 | if (!af) | |
1079 | continue; | |
1080 | ||
1081 | af->from_addr_param(paddr, params.addr, sh->source, 0); | |
1082 | ||
1083 | asoc = __sctp_lookup_association(net, laddr, paddr, transportp); | |
1084 | if (asoc) | |
1085 | return asoc; | |
1086 | } | |
1087 | ||
1088 | return NULL; | |
1089 | } | |
1090 | ||
1091 | /* ADD-IP, Section 5.2 | |
1092 | * When an endpoint receives an ASCONF Chunk from the remote peer | |
1093 | * special procedures may be needed to identify the association the | |
1094 | * ASCONF Chunk is associated with. To properly find the association | |
1095 | * the following procedures SHOULD be followed: | |
1096 | * | |
1097 | * D2) If the association is not found, use the address found in the | |
1098 | * Address Parameter TLV combined with the port number found in the | |
1099 | * SCTP common header. If found proceed to rule D4. | |
1100 | * | |
1101 | * D2-ext) If more than one ASCONF Chunks are packed together, use the | |
1102 | * address found in the ASCONF Address Parameter TLV of each of the | |
1103 | * subsequent ASCONF Chunks. If found, proceed to rule D4. | |
1104 | */ | |
1105 | static struct sctp_association *__sctp_rcv_asconf_lookup( | |
1106 | struct net *net, | |
1107 | sctp_chunkhdr_t *ch, | |
1108 | const union sctp_addr *laddr, | |
1109 | __be16 peer_port, | |
1110 | struct sctp_transport **transportp) | |
1111 | { | |
1112 | sctp_addip_chunk_t *asconf = (struct sctp_addip_chunk *)ch; | |
1113 | struct sctp_af *af; | |
1114 | union sctp_addr_param *param; | |
1115 | union sctp_addr paddr; | |
1116 | ||
1117 | /* Skip over the ADDIP header and find the Address parameter */ | |
1118 | param = (union sctp_addr_param *)(asconf + 1); | |
1119 | ||
1120 | af = sctp_get_af_specific(param_type2af(param->p.type)); | |
1121 | if (unlikely(!af)) | |
1122 | return NULL; | |
1123 | ||
1124 | af->from_addr_param(&paddr, param, peer_port, 0); | |
1125 | ||
1126 | return __sctp_lookup_association(net, laddr, &paddr, transportp); | |
1127 | } | |
1128 | ||
1129 | ||
1130 | /* SCTP-AUTH, Section 6.3: | |
1131 | * If the receiver does not find a STCB for a packet containing an AUTH | |
1132 | * chunk as the first chunk and not a COOKIE-ECHO chunk as the second | |
1133 | * chunk, it MUST use the chunks after the AUTH chunk to look up an existing | |
1134 | * association. | |
1135 | * | |
1136 | * This means that any chunks that can help us identify the association need | |
1137 | * to be looked at to find this association. | |
1138 | */ | |
1139 | static struct sctp_association *__sctp_rcv_walk_lookup(struct net *net, | |
1140 | struct sk_buff *skb, | |
1141 | const union sctp_addr *laddr, | |
1142 | struct sctp_transport **transportp) | |
1143 | { | |
1144 | struct sctp_association *asoc = NULL; | |
1145 | sctp_chunkhdr_t *ch; | |
1146 | int have_auth = 0; | |
1147 | unsigned int chunk_num = 1; | |
1148 | __u8 *ch_end; | |
1149 | ||
1150 | /* Walk through the chunks looking for AUTH or ASCONF chunks | |
1151 | * to help us find the association. | |
1152 | */ | |
1153 | ch = (sctp_chunkhdr_t *) skb->data; | |
1154 | do { | |
1155 | /* Break out if chunk length is less then minimal. */ | |
1156 | if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t)) | |
1157 | break; | |
1158 | ||
1159 | ch_end = ((__u8 *)ch) + SCTP_PAD4(ntohs(ch->length)); | |
1160 | if (ch_end > skb_tail_pointer(skb)) | |
1161 | break; | |
1162 | ||
1163 | switch (ch->type) { | |
1164 | case SCTP_CID_AUTH: | |
1165 | have_auth = chunk_num; | |
1166 | break; | |
1167 | ||
1168 | case SCTP_CID_COOKIE_ECHO: | |
1169 | /* If a packet arrives containing an AUTH chunk as | |
1170 | * a first chunk, a COOKIE-ECHO chunk as the second | |
1171 | * chunk, and possibly more chunks after them, and | |
1172 | * the receiver does not have an STCB for that | |
1173 | * packet, then authentication is based on | |
1174 | * the contents of the COOKIE- ECHO chunk. | |
1175 | */ | |
1176 | if (have_auth == 1 && chunk_num == 2) | |
1177 | return NULL; | |
1178 | break; | |
1179 | ||
1180 | case SCTP_CID_ASCONF: | |
1181 | if (have_auth || net->sctp.addip_noauth) | |
1182 | asoc = __sctp_rcv_asconf_lookup( | |
1183 | net, ch, laddr, | |
1184 | sctp_hdr(skb)->source, | |
1185 | transportp); | |
1186 | default: | |
1187 | break; | |
1188 | } | |
1189 | ||
1190 | if (asoc) | |
1191 | break; | |
1192 | ||
1193 | ch = (sctp_chunkhdr_t *) ch_end; | |
1194 | chunk_num++; | |
1195 | } while (ch_end < skb_tail_pointer(skb)); | |
1196 | ||
1197 | return asoc; | |
1198 | } | |
1199 | ||
1200 | /* | |
1201 | * There are circumstances when we need to look inside the SCTP packet | |
1202 | * for information to help us find the association. Examples | |
1203 | * include looking inside of INIT/INIT-ACK chunks or after the AUTH | |
1204 | * chunks. | |
1205 | */ | |
1206 | static struct sctp_association *__sctp_rcv_lookup_harder(struct net *net, | |
1207 | struct sk_buff *skb, | |
1208 | const union sctp_addr *laddr, | |
1209 | struct sctp_transport **transportp) | |
1210 | { | |
1211 | sctp_chunkhdr_t *ch; | |
1212 | ||
1213 | /* We do not allow GSO frames here as we need to linearize and | |
1214 | * then cannot guarantee frame boundaries. This shouldn't be an | |
1215 | * issue as packets hitting this are mostly INIT or INIT-ACK and | |
1216 | * those cannot be on GSO-style anyway. | |
1217 | */ | |
1218 | if ((skb_shinfo(skb)->gso_type & SKB_GSO_SCTP) == SKB_GSO_SCTP) | |
1219 | return NULL; | |
1220 | ||
1221 | ch = (sctp_chunkhdr_t *) skb->data; | |
1222 | ||
1223 | /* The code below will attempt to walk the chunk and extract | |
1224 | * parameter information. Before we do that, we need to verify | |
1225 | * that the chunk length doesn't cause overflow. Otherwise, we'll | |
1226 | * walk off the end. | |
1227 | */ | |
1228 | if (SCTP_PAD4(ntohs(ch->length)) > skb->len) | |
1229 | return NULL; | |
1230 | ||
1231 | /* If this is INIT/INIT-ACK look inside the chunk too. */ | |
1232 | if (ch->type == SCTP_CID_INIT || ch->type == SCTP_CID_INIT_ACK) | |
1233 | return __sctp_rcv_init_lookup(net, skb, laddr, transportp); | |
1234 | ||
1235 | return __sctp_rcv_walk_lookup(net, skb, laddr, transportp); | |
1236 | } | |
1237 | ||
1238 | /* Lookup an association for an inbound skb. */ | |
1239 | static struct sctp_association *__sctp_rcv_lookup(struct net *net, | |
1240 | struct sk_buff *skb, | |
1241 | const union sctp_addr *paddr, | |
1242 | const union sctp_addr *laddr, | |
1243 | struct sctp_transport **transportp) | |
1244 | { | |
1245 | struct sctp_association *asoc; | |
1246 | ||
1247 | asoc = __sctp_lookup_association(net, laddr, paddr, transportp); | |
1248 | if (asoc) | |
1249 | goto out; | |
1250 | ||
1251 | /* Further lookup for INIT/INIT-ACK packets. | |
1252 | * SCTP Implementors Guide, 2.18 Handling of address | |
1253 | * parameters within the INIT or INIT-ACK. | |
1254 | */ | |
1255 | asoc = __sctp_rcv_lookup_harder(net, skb, laddr, transportp); | |
1256 | if (asoc) | |
1257 | goto out; | |
1258 | ||
1259 | if (paddr->sa.sa_family == AF_INET) | |
1260 | pr_debug("sctp: asoc not found for src:%pI4:%d dst:%pI4:%d\n", | |
1261 | &laddr->v4.sin_addr, ntohs(laddr->v4.sin_port), | |
1262 | &paddr->v4.sin_addr, ntohs(paddr->v4.sin_port)); | |
1263 | else | |
1264 | pr_debug("sctp: asoc not found for src:%pI6:%d dst:%pI6:%d\n", | |
1265 | &laddr->v6.sin6_addr, ntohs(laddr->v6.sin6_port), | |
1266 | &paddr->v6.sin6_addr, ntohs(paddr->v6.sin6_port)); | |
1267 | ||
1268 | out: | |
1269 | return asoc; | |
1270 | } |