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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. */ | |
48 | static int sctp_rcv_ootb(struct sk_buff *); | |
49 | static 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 | static struct sctp_endpoint *__sctp_rcv_lookup_endpoint( | |
55 | struct net *net, struct sk_buff *skb, | |
56 | const union sctp_addr *laddr, | |
57 | const union sctp_addr *daddr); | |
58 | static struct sctp_association *__sctp_lookup_association( | |
59 | struct net *net, | |
60 | const union sctp_addr *local, | |
61 | const union sctp_addr *peer, | |
62 | struct sctp_transport **pt); | |
63 | ||
64 | static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb); | |
65 | ||
66 | ||
67 | /* Calculate the SCTP checksum of an SCTP packet. */ | |
68 | static inline int sctp_rcv_checksum(struct net *net, struct sk_buff *skb) | |
69 | { | |
70 | struct sctphdr *sh = sctp_hdr(skb); | |
71 | __le32 cmp = sh->checksum; | |
72 | __le32 val = sctp_compute_cksum(skb, 0); | |
73 | ||
74 | if (val != cmp) { | |
75 | /* CRC failure, dump it. */ | |
76 | __SCTP_INC_STATS(net, SCTP_MIB_CHECKSUMERRORS); | |
77 | return -1; | |
78 | } | |
79 | return 0; | |
80 | } | |
81 | ||
82 | /* | |
83 | * This is the routine which IP calls when receiving an SCTP packet. | |
84 | */ | |
85 | int sctp_rcv(struct sk_buff *skb) | |
86 | { | |
87 | struct sock *sk; | |
88 | struct sctp_association *asoc; | |
89 | struct sctp_endpoint *ep = NULL; | |
90 | struct sctp_ep_common *rcvr; | |
91 | struct sctp_transport *transport = NULL; | |
92 | struct sctp_chunk *chunk; | |
93 | union sctp_addr src; | |
94 | union sctp_addr dest; | |
95 | int family; | |
96 | struct sctp_af *af; | |
97 | struct net *net = dev_net(skb->dev); | |
98 | bool is_gso = skb_is_gso(skb) && skb_is_gso_sctp(skb); | |
99 | ||
100 | if (skb->pkt_type != PACKET_HOST) | |
101 | goto discard_it; | |
102 | ||
103 | __SCTP_INC_STATS(net, SCTP_MIB_INSCTPPACKS); | |
104 | ||
105 | /* If packet is too small to contain a single chunk, let's not | |
106 | * waste time on it anymore. | |
107 | */ | |
108 | if (skb->len < sizeof(struct sctphdr) + sizeof(struct sctp_chunkhdr) + | |
109 | skb_transport_offset(skb)) | |
110 | goto discard_it; | |
111 | ||
112 | /* If the packet is fragmented and we need to do crc checking, | |
113 | * it's better to just linearize it otherwise crc computing | |
114 | * takes longer. | |
115 | */ | |
116 | if ((!is_gso && skb_linearize(skb)) || | |
117 | !pskb_may_pull(skb, sizeof(struct sctphdr))) | |
118 | goto discard_it; | |
119 | ||
120 | /* Pull up the IP header. */ | |
121 | __skb_pull(skb, skb_transport_offset(skb)); | |
122 | ||
123 | skb->csum_valid = 0; /* Previous value not applicable */ | |
124 | if (skb_csum_unnecessary(skb)) | |
125 | __skb_decr_checksum_unnecessary(skb); | |
126 | else if (!sctp_checksum_disable && | |
127 | !is_gso && | |
128 | sctp_rcv_checksum(net, skb) < 0) | |
129 | goto discard_it; | |
130 | skb->csum_valid = 1; | |
131 | ||
132 | __skb_pull(skb, sizeof(struct sctphdr)); | |
133 | ||
134 | family = ipver2af(ip_hdr(skb)->version); | |
135 | af = sctp_get_af_specific(family); | |
136 | if (unlikely(!af)) | |
137 | goto discard_it; | |
138 | SCTP_INPUT_CB(skb)->af = af; | |
139 | ||
140 | /* Initialize local addresses for lookups. */ | |
141 | af->from_skb(&src, skb, 1); | |
142 | af->from_skb(&dest, skb, 0); | |
143 | ||
144 | /* If the packet is to or from a non-unicast address, | |
145 | * silently discard the packet. | |
146 | * | |
147 | * This is not clearly defined in the RFC except in section | |
148 | * 8.4 - OOTB handling. However, based on the book "Stream Control | |
149 | * Transmission Protocol" 2.1, "It is important to note that the | |
150 | * IP address of an SCTP transport address must be a routable | |
151 | * unicast address. In other words, IP multicast addresses and | |
152 | * IP broadcast addresses cannot be used in an SCTP transport | |
153 | * address." | |
154 | */ | |
155 | if (!af->addr_valid(&src, NULL, skb) || | |
156 | !af->addr_valid(&dest, NULL, skb)) | |
157 | goto discard_it; | |
158 | ||
159 | asoc = __sctp_rcv_lookup(net, skb, &src, &dest, &transport); | |
160 | ||
161 | if (!asoc) | |
162 | ep = __sctp_rcv_lookup_endpoint(net, skb, &dest, &src); | |
163 | ||
164 | /* Retrieve the common input handling substructure. */ | |
165 | rcvr = asoc ? &asoc->base : &ep->base; | |
166 | sk = rcvr->sk; | |
167 | ||
168 | /* | |
169 | * If a frame arrives on an interface and the receiving socket is | |
170 | * bound to another interface, via SO_BINDTODEVICE, treat it as OOTB | |
171 | */ | |
172 | if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb))) { | |
173 | if (transport) { | |
174 | sctp_transport_put(transport); | |
175 | asoc = NULL; | |
176 | transport = NULL; | |
177 | } else { | |
178 | sctp_endpoint_put(ep); | |
179 | ep = NULL; | |
180 | } | |
181 | sk = net->sctp.ctl_sock; | |
182 | ep = sctp_sk(sk)->ep; | |
183 | sctp_endpoint_hold(ep); | |
184 | rcvr = &ep->base; | |
185 | } | |
186 | ||
187 | /* | |
188 | * RFC 2960, 8.4 - Handle "Out of the blue" Packets. | |
189 | * An SCTP packet is called an "out of the blue" (OOTB) | |
190 | * packet if it is correctly formed, i.e., passed the | |
191 | * receiver's checksum check, but the receiver is not | |
192 | * able to identify the association to which this | |
193 | * packet belongs. | |
194 | */ | |
195 | if (!asoc) { | |
196 | if (sctp_rcv_ootb(skb)) { | |
197 | __SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES); | |
198 | goto discard_release; | |
199 | } | |
200 | } | |
201 | ||
202 | if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family)) | |
203 | goto discard_release; | |
204 | nf_reset(skb); | |
205 | ||
206 | if (sk_filter(sk, skb)) | |
207 | goto discard_release; | |
208 | ||
209 | /* Create an SCTP packet structure. */ | |
210 | chunk = sctp_chunkify(skb, asoc, sk, GFP_ATOMIC); | |
211 | if (!chunk) | |
212 | goto discard_release; | |
213 | SCTP_INPUT_CB(skb)->chunk = chunk; | |
214 | ||
215 | /* Remember what endpoint is to handle this packet. */ | |
216 | chunk->rcvr = rcvr; | |
217 | ||
218 | /* Remember the SCTP header. */ | |
219 | chunk->sctp_hdr = sctp_hdr(skb); | |
220 | ||
221 | /* Set the source and destination addresses of the incoming chunk. */ | |
222 | sctp_init_addrs(chunk, &src, &dest); | |
223 | ||
224 | /* Remember where we came from. */ | |
225 | chunk->transport = transport; | |
226 | ||
227 | /* Acquire access to the sock lock. Note: We are safe from other | |
228 | * bottom halves on this lock, but a user may be in the lock too, | |
229 | * so check if it is busy. | |
230 | */ | |
231 | bh_lock_sock(sk); | |
232 | ||
233 | if (sk != rcvr->sk) { | |
234 | /* Our cached sk is different from the rcvr->sk. This is | |
235 | * because migrate()/accept() may have moved the association | |
236 | * to a new socket and released all the sockets. So now we | |
237 | * are holding a lock on the old socket while the user may | |
238 | * be doing something with the new socket. Switch our veiw | |
239 | * of the current sk. | |
240 | */ | |
241 | bh_unlock_sock(sk); | |
242 | sk = rcvr->sk; | |
243 | bh_lock_sock(sk); | |
244 | } | |
245 | ||
246 | if (sock_owned_by_user(sk)) { | |
247 | if (sctp_add_backlog(sk, skb)) { | |
248 | bh_unlock_sock(sk); | |
249 | sctp_chunk_free(chunk); | |
250 | skb = NULL; /* sctp_chunk_free already freed the skb */ | |
251 | goto discard_release; | |
252 | } | |
253 | __SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_BACKLOG); | |
254 | } else { | |
255 | __SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_SOFTIRQ); | |
256 | sctp_inq_push(&chunk->rcvr->inqueue, chunk); | |
257 | } | |
258 | ||
259 | bh_unlock_sock(sk); | |
260 | ||
261 | /* Release the asoc/ep ref we took in the lookup calls. */ | |
262 | if (transport) | |
263 | sctp_transport_put(transport); | |
264 | else | |
265 | sctp_endpoint_put(ep); | |
266 | ||
267 | return 0; | |
268 | ||
269 | discard_it: | |
270 | __SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_DISCARDS); | |
271 | kfree_skb(skb); | |
272 | return 0; | |
273 | ||
274 | discard_release: | |
275 | /* Release the asoc/ep ref we took in the lookup calls. */ | |
276 | if (transport) | |
277 | sctp_transport_put(transport); | |
278 | else | |
279 | sctp_endpoint_put(ep); | |
280 | ||
281 | goto discard_it; | |
282 | } | |
283 | ||
284 | /* Process the backlog queue of the socket. Every skb on | |
285 | * the backlog holds a ref on an association or endpoint. | |
286 | * We hold this ref throughout the state machine to make | |
287 | * sure that the structure we need is still around. | |
288 | */ | |
289 | int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb) | |
290 | { | |
291 | struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk; | |
292 | struct sctp_inq *inqueue = &chunk->rcvr->inqueue; | |
293 | struct sctp_transport *t = chunk->transport; | |
294 | struct sctp_ep_common *rcvr = NULL; | |
295 | int backloged = 0; | |
296 | ||
297 | rcvr = chunk->rcvr; | |
298 | ||
299 | /* If the rcvr is dead then the association or endpoint | |
300 | * has been deleted and we can safely drop the chunk | |
301 | * and refs that we are holding. | |
302 | */ | |
303 | if (rcvr->dead) { | |
304 | sctp_chunk_free(chunk); | |
305 | goto done; | |
306 | } | |
307 | ||
308 | if (unlikely(rcvr->sk != sk)) { | |
309 | /* In this case, the association moved from one socket to | |
310 | * another. We are currently sitting on the backlog of the | |
311 | * old socket, so we need to move. | |
312 | * However, since we are here in the process context we | |
313 | * need to take make sure that the user doesn't own | |
314 | * the new socket when we process the packet. | |
315 | * If the new socket is user-owned, queue the chunk to the | |
316 | * backlog of the new socket without dropping any refs. | |
317 | * Otherwise, we can safely push the chunk on the inqueue. | |
318 | */ | |
319 | ||
320 | sk = rcvr->sk; | |
321 | local_bh_disable(); | |
322 | bh_lock_sock(sk); | |
323 | ||
324 | if (sock_owned_by_user(sk)) { | |
325 | if (sk_add_backlog(sk, skb, sk->sk_rcvbuf)) | |
326 | sctp_chunk_free(chunk); | |
327 | else | |
328 | backloged = 1; | |
329 | } else | |
330 | sctp_inq_push(inqueue, chunk); | |
331 | ||
332 | bh_unlock_sock(sk); | |
333 | local_bh_enable(); | |
334 | ||
335 | /* If the chunk was backloged again, don't drop refs */ | |
336 | if (backloged) | |
337 | return 0; | |
338 | } else { | |
339 | sctp_inq_push(inqueue, chunk); | |
340 | } | |
341 | ||
342 | done: | |
343 | /* Release the refs we took in sctp_add_backlog */ | |
344 | if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type) | |
345 | sctp_transport_put(t); | |
346 | else if (SCTP_EP_TYPE_SOCKET == rcvr->type) | |
347 | sctp_endpoint_put(sctp_ep(rcvr)); | |
348 | else | |
349 | BUG(); | |
350 | ||
351 | return 0; | |
352 | } | |
353 | ||
354 | static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb) | |
355 | { | |
356 | struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk; | |
357 | struct sctp_transport *t = chunk->transport; | |
358 | struct sctp_ep_common *rcvr = chunk->rcvr; | |
359 | int ret; | |
360 | ||
361 | ret = sk_add_backlog(sk, skb, sk->sk_rcvbuf); | |
362 | if (!ret) { | |
363 | /* Hold the assoc/ep while hanging on the backlog queue. | |
364 | * This way, we know structures we need will not disappear | |
365 | * from us | |
366 | */ | |
367 | if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type) | |
368 | sctp_transport_hold(t); | |
369 | else if (SCTP_EP_TYPE_SOCKET == rcvr->type) | |
370 | sctp_endpoint_hold(sctp_ep(rcvr)); | |
371 | else | |
372 | BUG(); | |
373 | } | |
374 | return ret; | |
375 | ||
376 | } | |
377 | ||
378 | /* Handle icmp frag needed error. */ | |
379 | void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc, | |
380 | struct sctp_transport *t, __u32 pmtu) | |
381 | { | |
382 | if (!t || (t->pathmtu <= pmtu)) | |
383 | return; | |
384 | ||
385 | if (sock_owned_by_user(sk)) { | |
386 | atomic_set(&t->mtu_info, pmtu); | |
387 | asoc->pmtu_pending = 1; | |
388 | t->pmtu_pending = 1; | |
389 | return; | |
390 | } | |
391 | ||
392 | if (!(t->param_flags & SPP_PMTUD_ENABLE)) | |
393 | /* We can't allow retransmitting in such case, as the | |
394 | * retransmission would be sized just as before, and thus we | |
395 | * would get another icmp, and retransmit again. | |
396 | */ | |
397 | return; | |
398 | ||
399 | /* Update transports view of the MTU. Return if no update was needed. | |
400 | * If an update wasn't needed/possible, it also doesn't make sense to | |
401 | * try to retransmit now. | |
402 | */ | |
403 | if (!sctp_transport_update_pmtu(t, pmtu)) | |
404 | return; | |
405 | ||
406 | /* Update association pmtu. */ | |
407 | sctp_assoc_sync_pmtu(asoc); | |
408 | ||
409 | /* Retransmit with the new pmtu setting. */ | |
410 | sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD); | |
411 | } | |
412 | ||
413 | void sctp_icmp_redirect(struct sock *sk, struct sctp_transport *t, | |
414 | struct sk_buff *skb) | |
415 | { | |
416 | struct dst_entry *dst; | |
417 | ||
418 | if (sock_owned_by_user(sk) || !t) | |
419 | return; | |
420 | dst = sctp_transport_dst_check(t); | |
421 | if (dst) | |
422 | dst->ops->redirect(dst, sk, skb); | |
423 | } | |
424 | ||
425 | /* | |
426 | * SCTP Implementer's Guide, 2.37 ICMP handling procedures | |
427 | * | |
428 | * ICMP8) If the ICMP code is a "Unrecognized next header type encountered" | |
429 | * or a "Protocol Unreachable" treat this message as an abort | |
430 | * with the T bit set. | |
431 | * | |
432 | * This function sends an event to the state machine, which will abort the | |
433 | * association. | |
434 | * | |
435 | */ | |
436 | void sctp_icmp_proto_unreachable(struct sock *sk, | |
437 | struct sctp_association *asoc, | |
438 | struct sctp_transport *t) | |
439 | { | |
440 | if (sock_owned_by_user(sk)) { | |
441 | if (timer_pending(&t->proto_unreach_timer)) | |
442 | return; | |
443 | else { | |
444 | if (!mod_timer(&t->proto_unreach_timer, | |
445 | jiffies + (HZ/20))) | |
446 | sctp_association_hold(asoc); | |
447 | } | |
448 | } else { | |
449 | struct net *net = sock_net(sk); | |
450 | ||
451 | pr_debug("%s: unrecognized next header type " | |
452 | "encountered!\n", __func__); | |
453 | ||
454 | if (del_timer(&t->proto_unreach_timer)) | |
455 | sctp_association_put(asoc); | |
456 | ||
457 | sctp_do_sm(net, SCTP_EVENT_T_OTHER, | |
458 | SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH), | |
459 | asoc->state, asoc->ep, asoc, t, | |
460 | GFP_ATOMIC); | |
461 | } | |
462 | } | |
463 | ||
464 | /* Common lookup code for icmp/icmpv6 error handler. */ | |
465 | struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *skb, | |
466 | struct sctphdr *sctphdr, | |
467 | struct sctp_association **app, | |
468 | struct sctp_transport **tpp) | |
469 | { | |
470 | struct sctp_init_chunk *chunkhdr, _chunkhdr; | |
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 | __u32 vtag = ntohl(sctphdr->vtag); | |
478 | ||
479 | *app = NULL; *tpp = NULL; | |
480 | ||
481 | af = sctp_get_af_specific(family); | |
482 | if (unlikely(!af)) { | |
483 | return NULL; | |
484 | } | |
485 | ||
486 | /* Initialize local addresses for lookups. */ | |
487 | af->from_skb(&saddr, skb, 1); | |
488 | af->from_skb(&daddr, skb, 0); | |
489 | ||
490 | /* Look for an association that matches the incoming ICMP error | |
491 | * packet. | |
492 | */ | |
493 | asoc = __sctp_lookup_association(net, &saddr, &daddr, &transport); | |
494 | if (!asoc) | |
495 | return NULL; | |
496 | ||
497 | sk = asoc->base.sk; | |
498 | ||
499 | /* RFC 4960, Appendix C. ICMP Handling | |
500 | * | |
501 | * ICMP6) An implementation MUST validate that the Verification Tag | |
502 | * contained in the ICMP message matches the Verification Tag of | |
503 | * the peer. If the Verification Tag is not 0 and does NOT | |
504 | * match, discard the ICMP message. If it is 0 and the ICMP | |
505 | * message contains enough bytes to verify that the chunk type is | |
506 | * an INIT chunk and that the Initiate Tag matches the tag of the | |
507 | * peer, continue with ICMP7. If the ICMP message is too short | |
508 | * or the chunk type or the Initiate Tag does not match, silently | |
509 | * discard the packet. | |
510 | */ | |
511 | if (vtag == 0) { | |
512 | /* chunk header + first 4 octects of init header */ | |
513 | chunkhdr = skb_header_pointer(skb, skb_transport_offset(skb) + | |
514 | sizeof(struct sctphdr), | |
515 | sizeof(struct sctp_chunkhdr) + | |
516 | sizeof(__be32), &_chunkhdr); | |
517 | if (!chunkhdr || | |
518 | chunkhdr->chunk_hdr.type != SCTP_CID_INIT || | |
519 | ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag) | |
520 | goto out; | |
521 | ||
522 | } else if (vtag != asoc->c.peer_vtag) { | |
523 | goto out; | |
524 | } | |
525 | ||
526 | bh_lock_sock(sk); | |
527 | ||
528 | /* If too many ICMPs get dropped on busy | |
529 | * servers this needs to be solved differently. | |
530 | */ | |
531 | if (sock_owned_by_user(sk)) | |
532 | __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS); | |
533 | ||
534 | *app = asoc; | |
535 | *tpp = transport; | |
536 | return sk; | |
537 | ||
538 | out: | |
539 | sctp_transport_put(transport); | |
540 | return NULL; | |
541 | } | |
542 | ||
543 | /* Common cleanup code for icmp/icmpv6 error handler. */ | |
544 | void sctp_err_finish(struct sock *sk, struct sctp_transport *t) | |
545 | { | |
546 | bh_unlock_sock(sk); | |
547 | sctp_transport_put(t); | |
548 | } | |
549 | ||
550 | /* | |
551 | * This routine is called by the ICMP module when it gets some | |
552 | * sort of error condition. If err < 0 then the socket should | |
553 | * be closed and the error returned to the user. If err > 0 | |
554 | * it's just the icmp type << 8 | icmp code. After adjustment | |
555 | * header points to the first 8 bytes of the sctp header. We need | |
556 | * to find the appropriate port. | |
557 | * | |
558 | * The locking strategy used here is very "optimistic". When | |
559 | * someone else accesses the socket the ICMP is just dropped | |
560 | * and for some paths there is no check at all. | |
561 | * A more general error queue to queue errors for later handling | |
562 | * is probably better. | |
563 | * | |
564 | */ | |
565 | int sctp_v4_err(struct sk_buff *skb, __u32 info) | |
566 | { | |
567 | const struct iphdr *iph = (const struct iphdr *)skb->data; | |
568 | const int ihlen = iph->ihl * 4; | |
569 | const int type = icmp_hdr(skb)->type; | |
570 | const int code = icmp_hdr(skb)->code; | |
571 | struct sock *sk; | |
572 | struct sctp_association *asoc = NULL; | |
573 | struct sctp_transport *transport; | |
574 | struct inet_sock *inet; | |
575 | __u16 saveip, savesctp; | |
576 | int err; | |
577 | struct net *net = dev_net(skb->dev); | |
578 | ||
579 | /* Fix up skb to look at the embedded net header. */ | |
580 | saveip = skb->network_header; | |
581 | savesctp = skb->transport_header; | |
582 | skb_reset_network_header(skb); | |
583 | skb_set_transport_header(skb, ihlen); | |
584 | sk = sctp_err_lookup(net, AF_INET, skb, sctp_hdr(skb), &asoc, &transport); | |
585 | /* Put back, the original values. */ | |
586 | skb->network_header = saveip; | |
587 | skb->transport_header = savesctp; | |
588 | if (!sk) { | |
589 | __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); | |
590 | return -ENOENT; | |
591 | } | |
592 | /* Warning: The sock lock is held. Remember to call | |
593 | * sctp_err_finish! | |
594 | */ | |
595 | ||
596 | switch (type) { | |
597 | case ICMP_PARAMETERPROB: | |
598 | err = EPROTO; | |
599 | break; | |
600 | case ICMP_DEST_UNREACH: | |
601 | if (code > NR_ICMP_UNREACH) | |
602 | goto out_unlock; | |
603 | ||
604 | /* PMTU discovery (RFC1191) */ | |
605 | if (ICMP_FRAG_NEEDED == code) { | |
606 | sctp_icmp_frag_needed(sk, asoc, transport, | |
607 | SCTP_TRUNC4(info)); | |
608 | goto out_unlock; | |
609 | } else { | |
610 | if (ICMP_PROT_UNREACH == code) { | |
611 | sctp_icmp_proto_unreachable(sk, asoc, | |
612 | transport); | |
613 | goto out_unlock; | |
614 | } | |
615 | } | |
616 | err = icmp_err_convert[code].errno; | |
617 | break; | |
618 | case ICMP_TIME_EXCEEDED: | |
619 | /* Ignore any time exceeded errors due to fragment reassembly | |
620 | * timeouts. | |
621 | */ | |
622 | if (ICMP_EXC_FRAGTIME == code) | |
623 | goto out_unlock; | |
624 | ||
625 | err = EHOSTUNREACH; | |
626 | break; | |
627 | case ICMP_REDIRECT: | |
628 | sctp_icmp_redirect(sk, transport, skb); | |
629 | /* Fall through to out_unlock. */ | |
630 | default: | |
631 | goto out_unlock; | |
632 | } | |
633 | ||
634 | inet = inet_sk(sk); | |
635 | if (!sock_owned_by_user(sk) && inet->recverr) { | |
636 | sk->sk_err = err; | |
637 | sk->sk_error_report(sk); | |
638 | } else { /* Only an error on timeout */ | |
639 | sk->sk_err_soft = err; | |
640 | } | |
641 | ||
642 | out_unlock: | |
643 | sctp_err_finish(sk, transport); | |
644 | return 0; | |
645 | } | |
646 | ||
647 | /* | |
648 | * RFC 2960, 8.4 - Handle "Out of the blue" Packets. | |
649 | * | |
650 | * This function scans all the chunks in the OOTB packet to determine if | |
651 | * the packet should be discarded right away. If a response might be needed | |
652 | * for this packet, or, if further processing is possible, the packet will | |
653 | * be queued to a proper inqueue for the next phase of handling. | |
654 | * | |
655 | * Output: | |
656 | * Return 0 - If further processing is needed. | |
657 | * Return 1 - If the packet can be discarded right away. | |
658 | */ | |
659 | static int sctp_rcv_ootb(struct sk_buff *skb) | |
660 | { | |
661 | struct sctp_chunkhdr *ch, _ch; | |
662 | int ch_end, offset = 0; | |
663 | ||
664 | /* Scan through all the chunks in the packet. */ | |
665 | do { | |
666 | /* Make sure we have at least the header there */ | |
667 | if (offset + sizeof(_ch) > skb->len) | |
668 | break; | |
669 | ||
670 | ch = skb_header_pointer(skb, offset, sizeof(*ch), &_ch); | |
671 | ||
672 | /* Break out if chunk length is less then minimal. */ | |
673 | if (ntohs(ch->length) < sizeof(_ch)) | |
674 | break; | |
675 | ||
676 | ch_end = offset + SCTP_PAD4(ntohs(ch->length)); | |
677 | if (ch_end > skb->len) | |
678 | break; | |
679 | ||
680 | /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the | |
681 | * receiver MUST silently discard the OOTB packet and take no | |
682 | * further action. | |
683 | */ | |
684 | if (SCTP_CID_ABORT == ch->type) | |
685 | goto discard; | |
686 | ||
687 | /* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE | |
688 | * chunk, the receiver should silently discard the packet | |
689 | * and take no further action. | |
690 | */ | |
691 | if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type) | |
692 | goto discard; | |
693 | ||
694 | /* RFC 4460, 2.11.2 | |
695 | * This will discard packets with INIT chunk bundled as | |
696 | * subsequent chunks in the packet. When INIT is first, | |
697 | * the normal INIT processing will discard the chunk. | |
698 | */ | |
699 | if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data) | |
700 | goto discard; | |
701 | ||
702 | offset = ch_end; | |
703 | } while (ch_end < skb->len); | |
704 | ||
705 | return 0; | |
706 | ||
707 | discard: | |
708 | return 1; | |
709 | } | |
710 | ||
711 | /* Insert endpoint into the hash table. */ | |
712 | static int __sctp_hash_endpoint(struct sctp_endpoint *ep) | |
713 | { | |
714 | struct sock *sk = ep->base.sk; | |
715 | struct net *net = sock_net(sk); | |
716 | struct sctp_hashbucket *head; | |
717 | struct sctp_ep_common *epb; | |
718 | ||
719 | epb = &ep->base; | |
720 | epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port); | |
721 | head = &sctp_ep_hashtable[epb->hashent]; | |
722 | ||
723 | if (sk->sk_reuseport) { | |
724 | bool any = sctp_is_ep_boundall(sk); | |
725 | struct sctp_ep_common *epb2; | |
726 | struct list_head *list; | |
727 | int cnt = 0, err = 1; | |
728 | ||
729 | list_for_each(list, &ep->base.bind_addr.address_list) | |
730 | cnt++; | |
731 | ||
732 | sctp_for_each_hentry(epb2, &head->chain) { | |
733 | struct sock *sk2 = epb2->sk; | |
734 | ||
735 | if (!net_eq(sock_net(sk2), net) || sk2 == sk || | |
736 | !uid_eq(sock_i_uid(sk2), sock_i_uid(sk)) || | |
737 | !sk2->sk_reuseport) | |
738 | continue; | |
739 | ||
740 | err = sctp_bind_addrs_check(sctp_sk(sk2), | |
741 | sctp_sk(sk), cnt); | |
742 | if (!err) { | |
743 | err = reuseport_add_sock(sk, sk2, any); | |
744 | if (err) | |
745 | return err; | |
746 | break; | |
747 | } else if (err < 0) { | |
748 | return err; | |
749 | } | |
750 | } | |
751 | ||
752 | if (err) { | |
753 | err = reuseport_alloc(sk, any); | |
754 | if (err) | |
755 | return err; | |
756 | } | |
757 | } | |
758 | ||
759 | write_lock(&head->lock); | |
760 | hlist_add_head(&epb->node, &head->chain); | |
761 | write_unlock(&head->lock); | |
762 | return 0; | |
763 | } | |
764 | ||
765 | /* Add an endpoint to the hash. Local BH-safe. */ | |
766 | int sctp_hash_endpoint(struct sctp_endpoint *ep) | |
767 | { | |
768 | int err; | |
769 | ||
770 | local_bh_disable(); | |
771 | err = __sctp_hash_endpoint(ep); | |
772 | local_bh_enable(); | |
773 | ||
774 | return err; | |
775 | } | |
776 | ||
777 | /* Remove endpoint from the hash table. */ | |
778 | static void __sctp_unhash_endpoint(struct sctp_endpoint *ep) | |
779 | { | |
780 | struct sock *sk = ep->base.sk; | |
781 | struct sctp_hashbucket *head; | |
782 | struct sctp_ep_common *epb; | |
783 | ||
784 | epb = &ep->base; | |
785 | ||
786 | epb->hashent = sctp_ep_hashfn(sock_net(sk), epb->bind_addr.port); | |
787 | ||
788 | head = &sctp_ep_hashtable[epb->hashent]; | |
789 | ||
790 | if (rcu_access_pointer(sk->sk_reuseport_cb)) | |
791 | reuseport_detach_sock(sk); | |
792 | ||
793 | write_lock(&head->lock); | |
794 | hlist_del_init(&epb->node); | |
795 | write_unlock(&head->lock); | |
796 | } | |
797 | ||
798 | /* Remove endpoint from the hash. Local BH-safe. */ | |
799 | void sctp_unhash_endpoint(struct sctp_endpoint *ep) | |
800 | { | |
801 | local_bh_disable(); | |
802 | __sctp_unhash_endpoint(ep); | |
803 | local_bh_enable(); | |
804 | } | |
805 | ||
806 | static inline __u32 sctp_hashfn(const struct net *net, __be16 lport, | |
807 | const union sctp_addr *paddr, __u32 seed) | |
808 | { | |
809 | __u32 addr; | |
810 | ||
811 | if (paddr->sa.sa_family == AF_INET6) | |
812 | addr = jhash(&paddr->v6.sin6_addr, 16, seed); | |
813 | else | |
814 | addr = (__force __u32)paddr->v4.sin_addr.s_addr; | |
815 | ||
816 | return jhash_3words(addr, ((__force __u32)paddr->v4.sin_port) << 16 | | |
817 | (__force __u32)lport, net_hash_mix(net), seed); | |
818 | } | |
819 | ||
820 | /* Look up an endpoint. */ | |
821 | static struct sctp_endpoint *__sctp_rcv_lookup_endpoint( | |
822 | struct net *net, struct sk_buff *skb, | |
823 | const union sctp_addr *laddr, | |
824 | const union sctp_addr *paddr) | |
825 | { | |
826 | struct sctp_hashbucket *head; | |
827 | struct sctp_ep_common *epb; | |
828 | struct sctp_endpoint *ep; | |
829 | struct sock *sk; | |
830 | __be16 lport; | |
831 | int hash; | |
832 | ||
833 | lport = laddr->v4.sin_port; | |
834 | hash = sctp_ep_hashfn(net, ntohs(lport)); | |
835 | head = &sctp_ep_hashtable[hash]; | |
836 | read_lock(&head->lock); | |
837 | sctp_for_each_hentry(epb, &head->chain) { | |
838 | ep = sctp_ep(epb); | |
839 | if (sctp_endpoint_is_match(ep, net, laddr)) | |
840 | goto hit; | |
841 | } | |
842 | ||
843 | ep = sctp_sk(net->sctp.ctl_sock)->ep; | |
844 | ||
845 | hit: | |
846 | sk = ep->base.sk; | |
847 | if (sk->sk_reuseport) { | |
848 | __u32 phash = sctp_hashfn(net, lport, paddr, 0); | |
849 | ||
850 | sk = reuseport_select_sock(sk, phash, skb, | |
851 | sizeof(struct sctphdr)); | |
852 | if (sk) | |
853 | ep = sctp_sk(sk)->ep; | |
854 | } | |
855 | sctp_endpoint_hold(ep); | |
856 | read_unlock(&head->lock); | |
857 | return ep; | |
858 | } | |
859 | ||
860 | /* rhashtable for transport */ | |
861 | struct sctp_hash_cmp_arg { | |
862 | const union sctp_addr *paddr; | |
863 | const struct net *net; | |
864 | __be16 lport; | |
865 | }; | |
866 | ||
867 | static inline int sctp_hash_cmp(struct rhashtable_compare_arg *arg, | |
868 | const void *ptr) | |
869 | { | |
870 | struct sctp_transport *t = (struct sctp_transport *)ptr; | |
871 | const struct sctp_hash_cmp_arg *x = arg->key; | |
872 | int err = 1; | |
873 | ||
874 | if (!sctp_cmp_addr_exact(&t->ipaddr, x->paddr)) | |
875 | return err; | |
876 | if (!sctp_transport_hold(t)) | |
877 | return err; | |
878 | ||
879 | if (!net_eq(sock_net(t->asoc->base.sk), x->net)) | |
880 | goto out; | |
881 | if (x->lport != htons(t->asoc->base.bind_addr.port)) | |
882 | goto out; | |
883 | ||
884 | err = 0; | |
885 | out: | |
886 | sctp_transport_put(t); | |
887 | return err; | |
888 | } | |
889 | ||
890 | static inline __u32 sctp_hash_obj(const void *data, u32 len, u32 seed) | |
891 | { | |
892 | const struct sctp_transport *t = data; | |
893 | ||
894 | return sctp_hashfn(sock_net(t->asoc->base.sk), | |
895 | htons(t->asoc->base.bind_addr.port), | |
896 | &t->ipaddr, seed); | |
897 | } | |
898 | ||
899 | static inline __u32 sctp_hash_key(const void *data, u32 len, u32 seed) | |
900 | { | |
901 | const struct sctp_hash_cmp_arg *x = data; | |
902 | ||
903 | return sctp_hashfn(x->net, x->lport, x->paddr, seed); | |
904 | } | |
905 | ||
906 | static const struct rhashtable_params sctp_hash_params = { | |
907 | .head_offset = offsetof(struct sctp_transport, node), | |
908 | .hashfn = sctp_hash_key, | |
909 | .obj_hashfn = sctp_hash_obj, | |
910 | .obj_cmpfn = sctp_hash_cmp, | |
911 | .automatic_shrinking = true, | |
912 | }; | |
913 | ||
914 | int sctp_transport_hashtable_init(void) | |
915 | { | |
916 | return rhltable_init(&sctp_transport_hashtable, &sctp_hash_params); | |
917 | } | |
918 | ||
919 | void sctp_transport_hashtable_destroy(void) | |
920 | { | |
921 | rhltable_destroy(&sctp_transport_hashtable); | |
922 | } | |
923 | ||
924 | int sctp_hash_transport(struct sctp_transport *t) | |
925 | { | |
926 | struct sctp_transport *transport; | |
927 | struct rhlist_head *tmp, *list; | |
928 | struct sctp_hash_cmp_arg arg; | |
929 | int err; | |
930 | ||
931 | if (t->asoc->temp) | |
932 | return 0; | |
933 | ||
934 | arg.net = sock_net(t->asoc->base.sk); | |
935 | arg.paddr = &t->ipaddr; | |
936 | arg.lport = htons(t->asoc->base.bind_addr.port); | |
937 | ||
938 | rcu_read_lock(); | |
939 | list = rhltable_lookup(&sctp_transport_hashtable, &arg, | |
940 | sctp_hash_params); | |
941 | ||
942 | rhl_for_each_entry_rcu(transport, tmp, list, node) | |
943 | if (transport->asoc->ep == t->asoc->ep) { | |
944 | rcu_read_unlock(); | |
945 | return -EEXIST; | |
946 | } | |
947 | rcu_read_unlock(); | |
948 | ||
949 | err = rhltable_insert_key(&sctp_transport_hashtable, &arg, | |
950 | &t->node, sctp_hash_params); | |
951 | if (err) | |
952 | pr_err_once("insert transport fail, errno %d\n", err); | |
953 | ||
954 | return err; | |
955 | } | |
956 | ||
957 | void sctp_unhash_transport(struct sctp_transport *t) | |
958 | { | |
959 | if (t->asoc->temp) | |
960 | return; | |
961 | ||
962 | rhltable_remove(&sctp_transport_hashtable, &t->node, | |
963 | sctp_hash_params); | |
964 | } | |
965 | ||
966 | /* return a transport with holding it */ | |
967 | struct sctp_transport *sctp_addrs_lookup_transport( | |
968 | struct net *net, | |
969 | const union sctp_addr *laddr, | |
970 | const union sctp_addr *paddr) | |
971 | { | |
972 | struct rhlist_head *tmp, *list; | |
973 | struct sctp_transport *t; | |
974 | struct sctp_hash_cmp_arg arg = { | |
975 | .paddr = paddr, | |
976 | .net = net, | |
977 | .lport = laddr->v4.sin_port, | |
978 | }; | |
979 | ||
980 | list = rhltable_lookup(&sctp_transport_hashtable, &arg, | |
981 | sctp_hash_params); | |
982 | ||
983 | rhl_for_each_entry_rcu(t, tmp, list, node) { | |
984 | if (!sctp_transport_hold(t)) | |
985 | continue; | |
986 | ||
987 | if (sctp_bind_addr_match(&t->asoc->base.bind_addr, | |
988 | laddr, sctp_sk(t->asoc->base.sk))) | |
989 | return t; | |
990 | sctp_transport_put(t); | |
991 | } | |
992 | ||
993 | return NULL; | |
994 | } | |
995 | ||
996 | /* return a transport without holding it, as it's only used under sock lock */ | |
997 | struct sctp_transport *sctp_epaddr_lookup_transport( | |
998 | const struct sctp_endpoint *ep, | |
999 | const union sctp_addr *paddr) | |
1000 | { | |
1001 | struct net *net = sock_net(ep->base.sk); | |
1002 | struct rhlist_head *tmp, *list; | |
1003 | struct sctp_transport *t; | |
1004 | struct sctp_hash_cmp_arg arg = { | |
1005 | .paddr = paddr, | |
1006 | .net = net, | |
1007 | .lport = htons(ep->base.bind_addr.port), | |
1008 | }; | |
1009 | ||
1010 | list = rhltable_lookup(&sctp_transport_hashtable, &arg, | |
1011 | sctp_hash_params); | |
1012 | ||
1013 | rhl_for_each_entry_rcu(t, tmp, list, node) | |
1014 | if (ep == t->asoc->ep) | |
1015 | return t; | |
1016 | ||
1017 | return NULL; | |
1018 | } | |
1019 | ||
1020 | /* Look up an association. */ | |
1021 | static struct sctp_association *__sctp_lookup_association( | |
1022 | struct net *net, | |
1023 | const union sctp_addr *local, | |
1024 | const union sctp_addr *peer, | |
1025 | struct sctp_transport **pt) | |
1026 | { | |
1027 | struct sctp_transport *t; | |
1028 | struct sctp_association *asoc = NULL; | |
1029 | ||
1030 | t = sctp_addrs_lookup_transport(net, local, peer); | |
1031 | if (!t) | |
1032 | goto out; | |
1033 | ||
1034 | asoc = t->asoc; | |
1035 | *pt = t; | |
1036 | ||
1037 | out: | |
1038 | return asoc; | |
1039 | } | |
1040 | ||
1041 | /* Look up an association. protected by RCU read lock */ | |
1042 | static | |
1043 | struct sctp_association *sctp_lookup_association(struct net *net, | |
1044 | const union sctp_addr *laddr, | |
1045 | const union sctp_addr *paddr, | |
1046 | struct sctp_transport **transportp) | |
1047 | { | |
1048 | struct sctp_association *asoc; | |
1049 | ||
1050 | rcu_read_lock(); | |
1051 | asoc = __sctp_lookup_association(net, laddr, paddr, transportp); | |
1052 | rcu_read_unlock(); | |
1053 | ||
1054 | return asoc; | |
1055 | } | |
1056 | ||
1057 | /* Is there an association matching the given local and peer addresses? */ | |
1058 | bool sctp_has_association(struct net *net, | |
1059 | const union sctp_addr *laddr, | |
1060 | const union sctp_addr *paddr) | |
1061 | { | |
1062 | struct sctp_transport *transport; | |
1063 | ||
1064 | if (sctp_lookup_association(net, laddr, paddr, &transport)) { | |
1065 | sctp_transport_put(transport); | |
1066 | return true; | |
1067 | } | |
1068 | ||
1069 | return false; | |
1070 | } | |
1071 | ||
1072 | /* | |
1073 | * SCTP Implementors Guide, 2.18 Handling of address | |
1074 | * parameters within the INIT or INIT-ACK. | |
1075 | * | |
1076 | * D) When searching for a matching TCB upon reception of an INIT | |
1077 | * or INIT-ACK chunk the receiver SHOULD use not only the | |
1078 | * source address of the packet (containing the INIT or | |
1079 | * INIT-ACK) but the receiver SHOULD also use all valid | |
1080 | * address parameters contained within the chunk. | |
1081 | * | |
1082 | * 2.18.3 Solution description | |
1083 | * | |
1084 | * This new text clearly specifies to an implementor the need | |
1085 | * to look within the INIT or INIT-ACK. Any implementation that | |
1086 | * does not do this, may not be able to establish associations | |
1087 | * in certain circumstances. | |
1088 | * | |
1089 | */ | |
1090 | static struct sctp_association *__sctp_rcv_init_lookup(struct net *net, | |
1091 | struct sk_buff *skb, | |
1092 | const union sctp_addr *laddr, struct sctp_transport **transportp) | |
1093 | { | |
1094 | struct sctp_association *asoc; | |
1095 | union sctp_addr addr; | |
1096 | union sctp_addr *paddr = &addr; | |
1097 | struct sctphdr *sh = sctp_hdr(skb); | |
1098 | union sctp_params params; | |
1099 | struct sctp_init_chunk *init; | |
1100 | struct sctp_af *af; | |
1101 | ||
1102 | /* | |
1103 | * This code will NOT touch anything inside the chunk--it is | |
1104 | * strictly READ-ONLY. | |
1105 | * | |
1106 | * RFC 2960 3 SCTP packet Format | |
1107 | * | |
1108 | * Multiple chunks can be bundled into one SCTP packet up to | |
1109 | * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN | |
1110 | * COMPLETE chunks. These chunks MUST NOT be bundled with any | |
1111 | * other chunk in a packet. See Section 6.10 for more details | |
1112 | * on chunk bundling. | |
1113 | */ | |
1114 | ||
1115 | /* Find the start of the TLVs and the end of the chunk. This is | |
1116 | * the region we search for address parameters. | |
1117 | */ | |
1118 | init = (struct sctp_init_chunk *)skb->data; | |
1119 | ||
1120 | /* Walk the parameters looking for embedded addresses. */ | |
1121 | sctp_walk_params(params, init, init_hdr.params) { | |
1122 | ||
1123 | /* Note: Ignoring hostname addresses. */ | |
1124 | af = sctp_get_af_specific(param_type2af(params.p->type)); | |
1125 | if (!af) | |
1126 | continue; | |
1127 | ||
1128 | af->from_addr_param(paddr, params.addr, sh->source, 0); | |
1129 | ||
1130 | asoc = __sctp_lookup_association(net, laddr, paddr, transportp); | |
1131 | if (asoc) | |
1132 | return asoc; | |
1133 | } | |
1134 | ||
1135 | return NULL; | |
1136 | } | |
1137 | ||
1138 | /* ADD-IP, Section 5.2 | |
1139 | * When an endpoint receives an ASCONF Chunk from the remote peer | |
1140 | * special procedures may be needed to identify the association the | |
1141 | * ASCONF Chunk is associated with. To properly find the association | |
1142 | * the following procedures SHOULD be followed: | |
1143 | * | |
1144 | * D2) If the association is not found, use the address found in the | |
1145 | * Address Parameter TLV combined with the port number found in the | |
1146 | * SCTP common header. If found proceed to rule D4. | |
1147 | * | |
1148 | * D2-ext) If more than one ASCONF Chunks are packed together, use the | |
1149 | * address found in the ASCONF Address Parameter TLV of each of the | |
1150 | * subsequent ASCONF Chunks. If found, proceed to rule D4. | |
1151 | */ | |
1152 | static struct sctp_association *__sctp_rcv_asconf_lookup( | |
1153 | struct net *net, | |
1154 | struct sctp_chunkhdr *ch, | |
1155 | const union sctp_addr *laddr, | |
1156 | __be16 peer_port, | |
1157 | struct sctp_transport **transportp) | |
1158 | { | |
1159 | struct sctp_addip_chunk *asconf = (struct sctp_addip_chunk *)ch; | |
1160 | struct sctp_af *af; | |
1161 | union sctp_addr_param *param; | |
1162 | union sctp_addr paddr; | |
1163 | ||
1164 | /* Skip over the ADDIP header and find the Address parameter */ | |
1165 | param = (union sctp_addr_param *)(asconf + 1); | |
1166 | ||
1167 | af = sctp_get_af_specific(param_type2af(param->p.type)); | |
1168 | if (unlikely(!af)) | |
1169 | return NULL; | |
1170 | ||
1171 | af->from_addr_param(&paddr, param, peer_port, 0); | |
1172 | ||
1173 | return __sctp_lookup_association(net, laddr, &paddr, transportp); | |
1174 | } | |
1175 | ||
1176 | ||
1177 | /* SCTP-AUTH, Section 6.3: | |
1178 | * If the receiver does not find a STCB for a packet containing an AUTH | |
1179 | * chunk as the first chunk and not a COOKIE-ECHO chunk as the second | |
1180 | * chunk, it MUST use the chunks after the AUTH chunk to look up an existing | |
1181 | * association. | |
1182 | * | |
1183 | * This means that any chunks that can help us identify the association need | |
1184 | * to be looked at to find this association. | |
1185 | */ | |
1186 | static struct sctp_association *__sctp_rcv_walk_lookup(struct net *net, | |
1187 | struct sk_buff *skb, | |
1188 | const union sctp_addr *laddr, | |
1189 | struct sctp_transport **transportp) | |
1190 | { | |
1191 | struct sctp_association *asoc = NULL; | |
1192 | struct sctp_chunkhdr *ch; | |
1193 | int have_auth = 0; | |
1194 | unsigned int chunk_num = 1; | |
1195 | __u8 *ch_end; | |
1196 | ||
1197 | /* Walk through the chunks looking for AUTH or ASCONF chunks | |
1198 | * to help us find the association. | |
1199 | */ | |
1200 | ch = (struct sctp_chunkhdr *)skb->data; | |
1201 | do { | |
1202 | /* Break out if chunk length is less then minimal. */ | |
1203 | if (ntohs(ch->length) < sizeof(*ch)) | |
1204 | break; | |
1205 | ||
1206 | ch_end = ((__u8 *)ch) + SCTP_PAD4(ntohs(ch->length)); | |
1207 | if (ch_end > skb_tail_pointer(skb)) | |
1208 | break; | |
1209 | ||
1210 | switch (ch->type) { | |
1211 | case SCTP_CID_AUTH: | |
1212 | have_auth = chunk_num; | |
1213 | break; | |
1214 | ||
1215 | case SCTP_CID_COOKIE_ECHO: | |
1216 | /* If a packet arrives containing an AUTH chunk as | |
1217 | * a first chunk, a COOKIE-ECHO chunk as the second | |
1218 | * chunk, and possibly more chunks after them, and | |
1219 | * the receiver does not have an STCB for that | |
1220 | * packet, then authentication is based on | |
1221 | * the contents of the COOKIE- ECHO chunk. | |
1222 | */ | |
1223 | if (have_auth == 1 && chunk_num == 2) | |
1224 | return NULL; | |
1225 | break; | |
1226 | ||
1227 | case SCTP_CID_ASCONF: | |
1228 | if (have_auth || net->sctp.addip_noauth) | |
1229 | asoc = __sctp_rcv_asconf_lookup( | |
1230 | net, ch, laddr, | |
1231 | sctp_hdr(skb)->source, | |
1232 | transportp); | |
1233 | default: | |
1234 | break; | |
1235 | } | |
1236 | ||
1237 | if (asoc) | |
1238 | break; | |
1239 | ||
1240 | ch = (struct sctp_chunkhdr *)ch_end; | |
1241 | chunk_num++; | |
1242 | } while (ch_end < skb_tail_pointer(skb)); | |
1243 | ||
1244 | return asoc; | |
1245 | } | |
1246 | ||
1247 | /* | |
1248 | * There are circumstances when we need to look inside the SCTP packet | |
1249 | * for information to help us find the association. Examples | |
1250 | * include looking inside of INIT/INIT-ACK chunks or after the AUTH | |
1251 | * chunks. | |
1252 | */ | |
1253 | static struct sctp_association *__sctp_rcv_lookup_harder(struct net *net, | |
1254 | struct sk_buff *skb, | |
1255 | const union sctp_addr *laddr, | |
1256 | struct sctp_transport **transportp) | |
1257 | { | |
1258 | struct sctp_chunkhdr *ch; | |
1259 | ||
1260 | /* We do not allow GSO frames here as we need to linearize and | |
1261 | * then cannot guarantee frame boundaries. This shouldn't be an | |
1262 | * issue as packets hitting this are mostly INIT or INIT-ACK and | |
1263 | * those cannot be on GSO-style anyway. | |
1264 | */ | |
1265 | if (skb_is_gso(skb) && skb_is_gso_sctp(skb)) | |
1266 | return NULL; | |
1267 | ||
1268 | ch = (struct sctp_chunkhdr *)skb->data; | |
1269 | ||
1270 | /* The code below will attempt to walk the chunk and extract | |
1271 | * parameter information. Before we do that, we need to verify | |
1272 | * that the chunk length doesn't cause overflow. Otherwise, we'll | |
1273 | * walk off the end. | |
1274 | */ | |
1275 | if (SCTP_PAD4(ntohs(ch->length)) > skb->len) | |
1276 | return NULL; | |
1277 | ||
1278 | /* If this is INIT/INIT-ACK look inside the chunk too. */ | |
1279 | if (ch->type == SCTP_CID_INIT || ch->type == SCTP_CID_INIT_ACK) | |
1280 | return __sctp_rcv_init_lookup(net, skb, laddr, transportp); | |
1281 | ||
1282 | return __sctp_rcv_walk_lookup(net, skb, laddr, transportp); | |
1283 | } | |
1284 | ||
1285 | /* Lookup an association for an inbound skb. */ | |
1286 | static struct sctp_association *__sctp_rcv_lookup(struct net *net, | |
1287 | struct sk_buff *skb, | |
1288 | const union sctp_addr *paddr, | |
1289 | const union sctp_addr *laddr, | |
1290 | struct sctp_transport **transportp) | |
1291 | { | |
1292 | struct sctp_association *asoc; | |
1293 | ||
1294 | asoc = __sctp_lookup_association(net, laddr, paddr, transportp); | |
1295 | if (asoc) | |
1296 | goto out; | |
1297 | ||
1298 | /* Further lookup for INIT/INIT-ACK packets. | |
1299 | * SCTP Implementors Guide, 2.18 Handling of address | |
1300 | * parameters within the INIT or INIT-ACK. | |
1301 | */ | |
1302 | asoc = __sctp_rcv_lookup_harder(net, skb, laddr, transportp); | |
1303 | if (asoc) | |
1304 | goto out; | |
1305 | ||
1306 | if (paddr->sa.sa_family == AF_INET) | |
1307 | pr_debug("sctp: asoc not found for src:%pI4:%d dst:%pI4:%d\n", | |
1308 | &laddr->v4.sin_addr, ntohs(laddr->v4.sin_port), | |
1309 | &paddr->v4.sin_addr, ntohs(paddr->v4.sin_port)); | |
1310 | else | |
1311 | pr_debug("sctp: asoc not found for src:%pI6:%d dst:%pI6:%d\n", | |
1312 | &laddr->v6.sin6_addr, ntohs(laddr->v6.sin6_port), | |
1313 | &paddr->v6.sin6_addr, ntohs(paddr->v6.sin6_port)); | |
1314 | ||
1315 | out: | |
1316 | return asoc; | |
1317 | } |