1 /* SIP extension for IP connection tracking.
2 *
3 * (C) 2005 by Christian Hentschel <chentschel@arnet.com.ar>
4 * based on RR's ip_conntrack_ftp.c and other modules.
5 * (C) 2007 United Security Providers
6 * (C) 2007, 2008 Patrick McHardy <kaber@trash.net>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12
13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
14
15 #include <linux/module.h>
16 #include <linux/ctype.h>
17 #include <linux/skbuff.h>
18 #include <linux/inet.h>
19 #include <linux/in.h>
20 #include <linux/udp.h>
21 #include <linux/tcp.h>
22 #include <linux/netfilter.h>
23
24 #include <net/netfilter/nf_conntrack.h>
25 #include <net/netfilter/nf_conntrack_core.h>
26 #include <net/netfilter/nf_conntrack_expect.h>
27 #include <net/netfilter/nf_conntrack_helper.h>
28 #include <net/netfilter/nf_conntrack_zones.h>
29 #include <linux/netfilter/nf_conntrack_sip.h>
30
31 MODULE_LICENSE("GPL");
32 MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>");
33 MODULE_DESCRIPTION("SIP connection tracking helper");
34 MODULE_ALIAS("ip_conntrack_sip");
35 MODULE_ALIAS_NFCT_HELPER("sip");
36
37 #define MAX_PORTS 8
38 static unsigned short ports[MAX_PORTS];
39 static unsigned int ports_c;
40 module_param_array(ports, ushort, &ports_c, 0400);
41 MODULE_PARM_DESC(ports, "port numbers of SIP servers");
42
43 static unsigned int sip_timeout __read_mostly = SIP_TIMEOUT;
44 module_param(sip_timeout, uint, 0600);
45 MODULE_PARM_DESC(sip_timeout, "timeout for the master SIP session");
46
47 static int sip_direct_signalling __read_mostly = 1;
48 module_param(sip_direct_signalling, int, 0600);
49 MODULE_PARM_DESC(sip_direct_signalling, "expect incoming calls from registrar "
50 "only (default 1)");
51
52 static int sip_direct_media __read_mostly = 1;
53 module_param(sip_direct_media, int, 0600);
54 MODULE_PARM_DESC(sip_direct_media, "Expect Media streams between signalling "
55 "endpoints only (default 1)");
56
57 const struct nf_nat_sip_hooks *nf_nat_sip_hooks;
58 EXPORT_SYMBOL_GPL(nf_nat_sip_hooks);
59
60 static int string_len(const struct nf_conn *ct, const char *dptr,
61 const char *limit, int *shift)
62 {
63 int len = 0;
64
65 while (dptr < limit && isalpha(*dptr)) {
66 dptr++;
67 len++;
68 }
69 return len;
70 }
71
72 static int digits_len(const struct nf_conn *ct, const char *dptr,
73 const char *limit, int *shift)
74 {
75 int len = 0;
76 while (dptr < limit && isdigit(*dptr)) {
77 dptr++;
78 len++;
79 }
80 return len;
81 }
82
83 static int iswordc(const char c)
84 {
85 if (isalnum(c) || c == '!' || c == '"' || c == '%' ||
86 (c >= '(' && c <= '+') || c == ':' || c == '<' || c == '>' ||
87 c == '?' || (c >= '[' && c <= ']') || c == '_' || c == '`' ||
88 c == '{' || c == '}' || c == '~' || (c >= '-' && c <= '/') ||
89 c == '\'')
90 return 1;
91 return 0;
92 }
93
94 static int word_len(const char *dptr, const char *limit)
95 {
96 int len = 0;
97 while (dptr < limit && iswordc(*dptr)) {
98 dptr++;
99 len++;
100 }
101 return len;
102 }
103
104 static int callid_len(const struct nf_conn *ct, const char *dptr,
105 const char *limit, int *shift)
106 {
107 int len, domain_len;
108
109 len = word_len(dptr, limit);
110 dptr += len;
111 if (!len || dptr == limit || *dptr != '@')
112 return len;
113 dptr++;
114 len++;
115
116 domain_len = word_len(dptr, limit);
117 if (!domain_len)
118 return 0;
119 return len + domain_len;
120 }
121
122 /* get media type + port length */
123 static int media_len(const struct nf_conn *ct, const char *dptr,
124 const char *limit, int *shift)
125 {
126 int len = string_len(ct, dptr, limit, shift);
127
128 dptr += len;
129 if (dptr >= limit || *dptr != ' ')
130 return 0;
131 len++;
132 dptr++;
133
134 return len + digits_len(ct, dptr, limit, shift);
135 }
136
137 static int sip_parse_addr(const struct nf_conn *ct, const char *cp,
138 const char **endp, union nf_inet_addr *addr,
139 const char *limit, bool delim)
140 {
141 const char *end;
142 int ret;
143
144 if (!ct)
145 return 0;
146
147 memset(addr, 0, sizeof(*addr));
148 switch (nf_ct_l3num(ct)) {
149 case AF_INET:
150 ret = in4_pton(cp, limit - cp, (u8 *)&addr->ip, -1, &end);
151 if (ret == 0)
152 return 0;
153 break;
154 case AF_INET6:
155 if (cp < limit && *cp == '[')
156 cp++;
157 else if (delim)
158 return 0;
159
160 ret = in6_pton(cp, limit - cp, (u8 *)&addr->ip6, -1, &end);
161 if (ret == 0)
162 return 0;
163
164 if (end < limit && *end == ']')
165 end++;
166 else if (delim)
167 return 0;
168 break;
169 default:
170 BUG();
171 }
172
173 if (endp)
174 *endp = end;
175 return 1;
176 }
177
178 /* skip ip address. returns its length. */
179 static int epaddr_len(const struct nf_conn *ct, const char *dptr,
180 const char *limit, int *shift)
181 {
182 union nf_inet_addr addr;
183 const char *aux = dptr;
184
185 if (!sip_parse_addr(ct, dptr, &dptr, &addr, limit, true)) {
186 pr_debug("ip: %s parse failed.!\n", dptr);
187 return 0;
188 }
189
190 /* Port number */
191 if (*dptr == ':') {
192 dptr++;
193 dptr += digits_len(ct, dptr, limit, shift);
194 }
195 return dptr - aux;
196 }
197
198 /* get address length, skiping user info. */
199 static int skp_epaddr_len(const struct nf_conn *ct, const char *dptr,
200 const char *limit, int *shift)
201 {
202 const char *start = dptr;
203 int s = *shift;
204
205 /* Search for @, but stop at the end of the line.
206 * We are inside a sip: URI, so we don't need to worry about
207 * continuation lines. */
208 while (dptr < limit &&
209 *dptr != '@' && *dptr != '\r' && *dptr != '\n') {
210 (*shift)++;
211 dptr++;
212 }
213
214 if (dptr < limit && *dptr == '@') {
215 dptr++;
216 (*shift)++;
217 } else {
218 dptr = start;
219 *shift = s;
220 }
221
222 return epaddr_len(ct, dptr, limit, shift);
223 }
224
225 /* Parse a SIP request line of the form:
226 *
227 * Request-Line = Method SP Request-URI SP SIP-Version CRLF
228 *
229 * and return the offset and length of the address contained in the Request-URI.
230 */
231 int ct_sip_parse_request(const struct nf_conn *ct,
232 const char *dptr, unsigned int datalen,
233 unsigned int *matchoff, unsigned int *matchlen,
234 union nf_inet_addr *addr, __be16 *port)
235 {
236 const char *start = dptr, *limit = dptr + datalen, *end;
237 unsigned int mlen;
238 unsigned int p;
239 int shift = 0;
240
241 /* Skip method and following whitespace */
242 mlen = string_len(ct, dptr, limit, NULL);
243 if (!mlen)
244 return 0;
245 dptr += mlen;
246 if (++dptr >= limit)
247 return 0;
248
249 /* Find SIP URI */
250 for (; dptr < limit - strlen("sip:"); dptr++) {
251 if (*dptr == '\r' || *dptr == '\n')
252 return -1;
253 if (strncasecmp(dptr, "sip:", strlen("sip:")) == 0) {
254 dptr += strlen("sip:");
255 break;
256 }
257 }
258 if (!skp_epaddr_len(ct, dptr, limit, &shift))
259 return 0;
260 dptr += shift;
261
262 if (!sip_parse_addr(ct, dptr, &end, addr, limit, true))
263 return -1;
264 if (end < limit && *end == ':') {
265 end++;
266 p = simple_strtoul(end, (char **)&end, 10);
267 if (p < 1024 || p > 65535)
268 return -1;
269 *port = htons(p);
270 } else
271 *port = htons(SIP_PORT);
272
273 if (end == dptr)
274 return 0;
275 *matchoff = dptr - start;
276 *matchlen = end - dptr;
277 return 1;
278 }
279 EXPORT_SYMBOL_GPL(ct_sip_parse_request);
280
281 /* SIP header parsing: SIP headers are located at the beginning of a line, but
282 * may span several lines, in which case the continuation lines begin with a
283 * whitespace character. RFC 2543 allows lines to be terminated with CR, LF or
284 * CRLF, RFC 3261 allows only CRLF, we support both.
285 *
286 * Headers are followed by (optionally) whitespace, a colon, again (optionally)
287 * whitespace and the values. Whitespace in this context means any amount of
288 * tabs, spaces and continuation lines, which are treated as a single whitespace
289 * character.
290 *
291 * Some headers may appear multiple times. A comma separated list of values is
292 * equivalent to multiple headers.
293 */
294 static const struct sip_header ct_sip_hdrs[] = {
295 [SIP_HDR_CSEQ] = SIP_HDR("CSeq", NULL, NULL, digits_len),
296 [SIP_HDR_FROM] = SIP_HDR("From", "f", "sip:", skp_epaddr_len),
297 [SIP_HDR_TO] = SIP_HDR("To", "t", "sip:", skp_epaddr_len),
298 [SIP_HDR_CONTACT] = SIP_HDR("Contact", "m", "sip:", skp_epaddr_len),
299 [SIP_HDR_VIA_UDP] = SIP_HDR("Via", "v", "UDP ", epaddr_len),
300 [SIP_HDR_VIA_TCP] = SIP_HDR("Via", "v", "TCP ", epaddr_len),
301 [SIP_HDR_EXPIRES] = SIP_HDR("Expires", NULL, NULL, digits_len),
302 [SIP_HDR_CONTENT_LENGTH] = SIP_HDR("Content-Length", "l", NULL, digits_len),
303 [SIP_HDR_CALL_ID] = SIP_HDR("Call-Id", "i", NULL, callid_len),
304 };
305
306 static const char *sip_follow_continuation(const char *dptr, const char *limit)
307 {
308 /* Walk past newline */
309 if (++dptr >= limit)
310 return NULL;
311
312 /* Skip '\n' in CR LF */
313 if (*(dptr - 1) == '\r' && *dptr == '\n') {
314 if (++dptr >= limit)
315 return NULL;
316 }
317
318 /* Continuation line? */
319 if (*dptr != ' ' && *dptr != '\t')
320 return NULL;
321
322 /* skip leading whitespace */
323 for (; dptr < limit; dptr++) {
324 if (*dptr != ' ' && *dptr != '\t')
325 break;
326 }
327 return dptr;
328 }
329
330 static const char *sip_skip_whitespace(const char *dptr, const char *limit)
331 {
332 for (; dptr < limit; dptr++) {
333 if (*dptr == ' ' || *dptr == '\t')
334 continue;
335 if (*dptr != '\r' && *dptr != '\n')
336 break;
337 dptr = sip_follow_continuation(dptr, limit);
338 break;
339 }
340 return dptr;
341 }
342
343 /* Search within a SIP header value, dealing with continuation lines */
344 static const char *ct_sip_header_search(const char *dptr, const char *limit,
345 const char *needle, unsigned int len)
346 {
347 for (limit -= len; dptr < limit; dptr++) {
348 if (*dptr == '\r' || *dptr == '\n') {
349 dptr = sip_follow_continuation(dptr, limit);
350 if (dptr == NULL)
351 break;
352 continue;
353 }
354
355 if (strncasecmp(dptr, needle, len) == 0)
356 return dptr;
357 }
358 return NULL;
359 }
360
361 int ct_sip_get_header(const struct nf_conn *ct, const char *dptr,
362 unsigned int dataoff, unsigned int datalen,
363 enum sip_header_types type,
364 unsigned int *matchoff, unsigned int *matchlen)
365 {
366 const struct sip_header *hdr = &ct_sip_hdrs[type];
367 const char *start = dptr, *limit = dptr + datalen;
368 int shift = 0;
369
370 for (dptr += dataoff; dptr < limit; dptr++) {
371 /* Find beginning of line */
372 if (*dptr != '\r' && *dptr != '\n')
373 continue;
374 if (++dptr >= limit)
375 break;
376 if (*(dptr - 1) == '\r' && *dptr == '\n') {
377 if (++dptr >= limit)
378 break;
379 }
380
381 /* Skip continuation lines */
382 if (*dptr == ' ' || *dptr == '\t')
383 continue;
384
385 /* Find header. Compact headers must be followed by a
386 * non-alphabetic character to avoid mismatches. */
387 if (limit - dptr >= hdr->len &&
388 strncasecmp(dptr, hdr->name, hdr->len) == 0)
389 dptr += hdr->len;
390 else if (hdr->cname && limit - dptr >= hdr->clen + 1 &&
391 strncasecmp(dptr, hdr->cname, hdr->clen) == 0 &&
392 !isalpha(*(dptr + hdr->clen)))
393 dptr += hdr->clen;
394 else
395 continue;
396
397 /* Find and skip colon */
398 dptr = sip_skip_whitespace(dptr, limit);
399 if (dptr == NULL)
400 break;
401 if (*dptr != ':' || ++dptr >= limit)
402 break;
403
404 /* Skip whitespace after colon */
405 dptr = sip_skip_whitespace(dptr, limit);
406 if (dptr == NULL)
407 break;
408
409 *matchoff = dptr - start;
410 if (hdr->search) {
411 dptr = ct_sip_header_search(dptr, limit, hdr->search,
412 hdr->slen);
413 if (!dptr)
414 return -1;
415 dptr += hdr->slen;
416 }
417
418 *matchlen = hdr->match_len(ct, dptr, limit, &shift);
419 if (!*matchlen)
420 return -1;
421 *matchoff = dptr - start + shift;
422 return 1;
423 }
424 return 0;
425 }
426 EXPORT_SYMBOL_GPL(ct_sip_get_header);
427
428 /* Get next header field in a list of comma separated values */
429 static int ct_sip_next_header(const struct nf_conn *ct, const char *dptr,
430 unsigned int dataoff, unsigned int datalen,
431 enum sip_header_types type,
432 unsigned int *matchoff, unsigned int *matchlen)
433 {
434 const struct sip_header *hdr = &ct_sip_hdrs[type];
435 const char *start = dptr, *limit = dptr + datalen;
436 int shift = 0;
437
438 dptr += dataoff;
439
440 dptr = ct_sip_header_search(dptr, limit, ",", strlen(","));
441 if (!dptr)
442 return 0;
443
444 dptr = ct_sip_header_search(dptr, limit, hdr->search, hdr->slen);
445 if (!dptr)
446 return 0;
447 dptr += hdr->slen;
448
449 *matchoff = dptr - start;
450 *matchlen = hdr->match_len(ct, dptr, limit, &shift);
451 if (!*matchlen)
452 return -1;
453 *matchoff += shift;
454 return 1;
455 }
456
457 /* Walk through headers until a parsable one is found or no header of the
458 * given type is left. */
459 static int ct_sip_walk_headers(const struct nf_conn *ct, const char *dptr,
460 unsigned int dataoff, unsigned int datalen,
461 enum sip_header_types type, int *in_header,
462 unsigned int *matchoff, unsigned int *matchlen)
463 {
464 int ret;
465
466 if (in_header && *in_header) {
467 while (1) {
468 ret = ct_sip_next_header(ct, dptr, dataoff, datalen,
469 type, matchoff, matchlen);
470 if (ret > 0)
471 return ret;
472 if (ret == 0)
473 break;
474 dataoff += *matchoff;
475 }
476 *in_header = 0;
477 }
478
479 while (1) {
480 ret = ct_sip_get_header(ct, dptr, dataoff, datalen,
481 type, matchoff, matchlen);
482 if (ret > 0)
483 break;
484 if (ret == 0)
485 return ret;
486 dataoff += *matchoff;
487 }
488
489 if (in_header)
490 *in_header = 1;
491 return 1;
492 }
493
494 /* Locate a SIP header, parse the URI and return the offset and length of
495 * the address as well as the address and port themselves. A stream of
496 * headers can be parsed by handing in a non-NULL datalen and in_header
497 * pointer.
498 */
499 int ct_sip_parse_header_uri(const struct nf_conn *ct, const char *dptr,
500 unsigned int *dataoff, unsigned int datalen,
501 enum sip_header_types type, int *in_header,
502 unsigned int *matchoff, unsigned int *matchlen,
503 union nf_inet_addr *addr, __be16 *port)
504 {
505 const char *c, *limit = dptr + datalen;
506 unsigned int p;
507 int ret;
508
509 ret = ct_sip_walk_headers(ct, dptr, dataoff ? *dataoff : 0, datalen,
510 type, in_header, matchoff, matchlen);
511 WARN_ON(ret < 0);
512 if (ret == 0)
513 return ret;
514
515 if (!sip_parse_addr(ct, dptr + *matchoff, &c, addr, limit, true))
516 return -1;
517 if (*c == ':') {
518 c++;
519 p = simple_strtoul(c, (char **)&c, 10);
520 if (p < 1024 || p > 65535)
521 return -1;
522 *port = htons(p);
523 } else
524 *port = htons(SIP_PORT);
525
526 if (dataoff)
527 *dataoff = c - dptr;
528 return 1;
529 }
530 EXPORT_SYMBOL_GPL(ct_sip_parse_header_uri);
531
532 static int ct_sip_parse_param(const struct nf_conn *ct, const char *dptr,
533 unsigned int dataoff, unsigned int datalen,
534 const char *name,
535 unsigned int *matchoff, unsigned int *matchlen)
536 {
537 const char *limit = dptr + datalen;
538 const char *start;
539 const char *end;
540
541 limit = ct_sip_header_search(dptr + dataoff, limit, ",", strlen(","));
542 if (!limit)
543 limit = dptr + datalen;
544
545 start = ct_sip_header_search(dptr + dataoff, limit, name, strlen(name));
546 if (!start)
547 return 0;
548 start += strlen(name);
549
550 end = ct_sip_header_search(start, limit, ";", strlen(";"));
551 if (!end)
552 end = limit;
553
554 *matchoff = start - dptr;
555 *matchlen = end - start;
556 return 1;
557 }
558
559 /* Parse address from header parameter and return address, offset and length */
560 int ct_sip_parse_address_param(const struct nf_conn *ct, const char *dptr,
561 unsigned int dataoff, unsigned int datalen,
562 const char *name,
563 unsigned int *matchoff, unsigned int *matchlen,
564 union nf_inet_addr *addr, bool delim)
565 {
566 const char *limit = dptr + datalen;
567 const char *start, *end;
568
569 limit = ct_sip_header_search(dptr + dataoff, limit, ",", strlen(","));
570 if (!limit)
571 limit = dptr + datalen;
572
573 start = ct_sip_header_search(dptr + dataoff, limit, name, strlen(name));
574 if (!start)
575 return 0;
576
577 start += strlen(name);
578 if (!sip_parse_addr(ct, start, &end, addr, limit, delim))
579 return 0;
580 *matchoff = start - dptr;
581 *matchlen = end - start;
582 return 1;
583 }
584 EXPORT_SYMBOL_GPL(ct_sip_parse_address_param);
585
586 /* Parse numerical header parameter and return value, offset and length */
587 int ct_sip_parse_numerical_param(const struct nf_conn *ct, const char *dptr,
588 unsigned int dataoff, unsigned int datalen,
589 const char *name,
590 unsigned int *matchoff, unsigned int *matchlen,
591 unsigned int *val)
592 {
593 const char *limit = dptr + datalen;
594 const char *start;
595 char *end;
596
597 limit = ct_sip_header_search(dptr + dataoff, limit, ",", strlen(","));
598 if (!limit)
599 limit = dptr + datalen;
600
601 start = ct_sip_header_search(dptr + dataoff, limit, name, strlen(name));
602 if (!start)
603 return 0;
604
605 start += strlen(name);
606 *val = simple_strtoul(start, &end, 0);
607 if (start == end)
608 return 0;
609 if (matchoff && matchlen) {
610 *matchoff = start - dptr;
611 *matchlen = end - start;
612 }
613 return 1;
614 }
615 EXPORT_SYMBOL_GPL(ct_sip_parse_numerical_param);
616
617 static int ct_sip_parse_transport(struct nf_conn *ct, const char *dptr,
618 unsigned int dataoff, unsigned int datalen,
619 u8 *proto)
620 {
621 unsigned int matchoff, matchlen;
622
623 if (ct_sip_parse_param(ct, dptr, dataoff, datalen, "transport=",
624 &matchoff, &matchlen)) {
625 if (!strncasecmp(dptr + matchoff, "TCP", strlen("TCP")))
626 *proto = IPPROTO_TCP;
627 else if (!strncasecmp(dptr + matchoff, "UDP", strlen("UDP")))
628 *proto = IPPROTO_UDP;
629 else
630 return 0;
631
632 if (*proto != nf_ct_protonum(ct))
633 return 0;
634 } else
635 *proto = nf_ct_protonum(ct);
636
637 return 1;
638 }
639
640 static int sdp_parse_addr(const struct nf_conn *ct, const char *cp,
641 const char **endp, union nf_inet_addr *addr,
642 const char *limit)
643 {
644 const char *end;
645 int ret;
646
647 memset(addr, 0, sizeof(*addr));
648 switch (nf_ct_l3num(ct)) {
649 case AF_INET:
650 ret = in4_pton(cp, limit - cp, (u8 *)&addr->ip, -1, &end);
651 break;
652 case AF_INET6:
653 ret = in6_pton(cp, limit - cp, (u8 *)&addr->ip6, -1, &end);
654 break;
655 default:
656 BUG();
657 }
658
659 if (ret == 0)
660 return 0;
661 if (endp)
662 *endp = end;
663 return 1;
664 }
665
666 /* skip ip address. returns its length. */
667 static int sdp_addr_len(const struct nf_conn *ct, const char *dptr,
668 const char *limit, int *shift)
669 {
670 union nf_inet_addr addr;
671 const char *aux = dptr;
672
673 if (!sdp_parse_addr(ct, dptr, &dptr, &addr, limit)) {
674 pr_debug("ip: %s parse failed.!\n", dptr);
675 return 0;
676 }
677
678 return dptr - aux;
679 }
680
681 /* SDP header parsing: a SDP session description contains an ordered set of
682 * headers, starting with a section containing general session parameters,
683 * optionally followed by multiple media descriptions.
684 *
685 * SDP headers always start at the beginning of a line. According to RFC 2327:
686 * "The sequence CRLF (0x0d0a) is used to end a record, although parsers should
687 * be tolerant and also accept records terminated with a single newline
688 * character". We handle both cases.
689 */
690 static const struct sip_header ct_sdp_hdrs_v4[] = {
691 [SDP_HDR_VERSION] = SDP_HDR("v=", NULL, digits_len),
692 [SDP_HDR_OWNER] = SDP_HDR("o=", "IN IP4 ", sdp_addr_len),
693 [SDP_HDR_CONNECTION] = SDP_HDR("c=", "IN IP4 ", sdp_addr_len),
694 [SDP_HDR_MEDIA] = SDP_HDR("m=", NULL, media_len),
695 };
696
697 static const struct sip_header ct_sdp_hdrs_v6[] = {
698 [SDP_HDR_VERSION] = SDP_HDR("v=", NULL, digits_len),
699 [SDP_HDR_OWNER] = SDP_HDR("o=", "IN IP6 ", sdp_addr_len),
700 [SDP_HDR_CONNECTION] = SDP_HDR("c=", "IN IP6 ", sdp_addr_len),
701 [SDP_HDR_MEDIA] = SDP_HDR("m=", NULL, media_len),
702 };
703
704 /* Linear string search within SDP header values */
705 static const char *ct_sdp_header_search(const char *dptr, const char *limit,
706 const char *needle, unsigned int len)
707 {
708 for (limit -= len; dptr < limit; dptr++) {
709 if (*dptr == '\r' || *dptr == '\n')
710 break;
711 if (strncmp(dptr, needle, len) == 0)
712 return dptr;
713 }
714 return NULL;
715 }
716
717 /* Locate a SDP header (optionally a substring within the header value),
718 * optionally stopping at the first occurrence of the term header, parse
719 * it and return the offset and length of the data we're interested in.
720 */
721 int ct_sip_get_sdp_header(const struct nf_conn *ct, const char *dptr,
722 unsigned int dataoff, unsigned int datalen,
723 enum sdp_header_types type,
724 enum sdp_header_types term,
725 unsigned int *matchoff, unsigned int *matchlen)
726 {
727 const struct sip_header *hdrs, *hdr, *thdr;
728 const char *start = dptr, *limit = dptr + datalen;
729 int shift = 0;
730
731 hdrs = nf_ct_l3num(ct) == NFPROTO_IPV4 ? ct_sdp_hdrs_v4 : ct_sdp_hdrs_v6;
732 hdr = &hdrs[type];
733 thdr = &hdrs[term];
734
735 for (dptr += dataoff; dptr < limit; dptr++) {
736 /* Find beginning of line */
737 if (*dptr != '\r' && *dptr != '\n')
738 continue;
739 if (++dptr >= limit)
740 break;
741 if (*(dptr - 1) == '\r' && *dptr == '\n') {
742 if (++dptr >= limit)
743 break;
744 }
745
746 if (term != SDP_HDR_UNSPEC &&
747 limit - dptr >= thdr->len &&
748 strncasecmp(dptr, thdr->name, thdr->len) == 0)
749 break;
750 else if (limit - dptr >= hdr->len &&
751 strncasecmp(dptr, hdr->name, hdr->len) == 0)
752 dptr += hdr->len;
753 else
754 continue;
755
756 *matchoff = dptr - start;
757 if (hdr->search) {
758 dptr = ct_sdp_header_search(dptr, limit, hdr->search,
759 hdr->slen);
760 if (!dptr)
761 return -1;
762 dptr += hdr->slen;
763 }
764
765 *matchlen = hdr->match_len(ct, dptr, limit, &shift);
766 if (!*matchlen)
767 return -1;
768 *matchoff = dptr - start + shift;
769 return 1;
770 }
771 return 0;
772 }
773 EXPORT_SYMBOL_GPL(ct_sip_get_sdp_header);
774
775 static int ct_sip_parse_sdp_addr(const struct nf_conn *ct, const char *dptr,
776 unsigned int dataoff, unsigned int datalen,
777 enum sdp_header_types type,
778 enum sdp_header_types term,
779 unsigned int *matchoff, unsigned int *matchlen,
780 union nf_inet_addr *addr)
781 {
782 int ret;
783
784 ret = ct_sip_get_sdp_header(ct, dptr, dataoff, datalen, type, term,
785 matchoff, matchlen);
786 if (ret <= 0)
787 return ret;
788
789 if (!sdp_parse_addr(ct, dptr + *matchoff, NULL, addr,
790 dptr + *matchoff + *matchlen))
791 return -1;
792 return 1;
793 }
794
795 static int refresh_signalling_expectation(struct nf_conn *ct,
796 union nf_inet_addr *addr,
797 u8 proto, __be16 port,
798 unsigned int expires)
799 {
800 struct nf_conn_help *help = nfct_help(ct);
801 struct nf_conntrack_expect *exp;
802 struct hlist_node *next;
803 int found = 0;
804
805 spin_lock_bh(&nf_conntrack_expect_lock);
806 hlist_for_each_entry_safe(exp, next, &help->expectations, lnode) {
807 if (exp->class != SIP_EXPECT_SIGNALLING ||
808 !nf_inet_addr_cmp(&exp->tuple.dst.u3, addr) ||
809 exp->tuple.dst.protonum != proto ||
810 exp->tuple.dst.u.udp.port != port)
811 continue;
812 if (mod_timer_pending(&exp->timeout, jiffies + expires * HZ)) {
813 exp->flags &= ~NF_CT_EXPECT_INACTIVE;
814 found = 1;
815 break;
816 }
817 }
818 spin_unlock_bh(&nf_conntrack_expect_lock);
819 return found;
820 }
821
822 static void flush_expectations(struct nf_conn *ct, bool media)
823 {
824 struct nf_conn_help *help = nfct_help(ct);
825 struct nf_conntrack_expect *exp;
826 struct hlist_node *next;
827
828 spin_lock_bh(&nf_conntrack_expect_lock);
829 hlist_for_each_entry_safe(exp, next, &help->expectations, lnode) {
830 if ((exp->class != SIP_EXPECT_SIGNALLING) ^ media)
831 continue;
832 if (!del_timer(&exp->timeout))
833 continue;
834 nf_ct_unlink_expect(exp);
835 nf_ct_expect_put(exp);
836 if (!media)
837 break;
838 }
839 spin_unlock_bh(&nf_conntrack_expect_lock);
840 }
841
842 static int set_expected_rtp_rtcp(struct sk_buff *skb, unsigned int protoff,
843 unsigned int dataoff,
844 const char **dptr, unsigned int *datalen,
845 union nf_inet_addr *daddr, __be16 port,
846 enum sip_expectation_classes class,
847 unsigned int mediaoff, unsigned int medialen)
848 {
849 struct nf_conntrack_expect *exp, *rtp_exp, *rtcp_exp;
850 enum ip_conntrack_info ctinfo;
851 struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
852 struct net *net = nf_ct_net(ct);
853 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
854 union nf_inet_addr *saddr;
855 struct nf_conntrack_tuple tuple;
856 int direct_rtp = 0, skip_expect = 0, ret = NF_DROP;
857 u_int16_t base_port;
858 __be16 rtp_port, rtcp_port;
859 const struct nf_nat_sip_hooks *hooks;
860
861 saddr = NULL;
862 if (sip_direct_media) {
863 if (!nf_inet_addr_cmp(daddr, &ct->tuplehash[dir].tuple.src.u3))
864 return NF_ACCEPT;
865 saddr = &ct->tuplehash[!dir].tuple.src.u3;
866 }
867
868 /* We need to check whether the registration exists before attempting
869 * to register it since we can see the same media description multiple
870 * times on different connections in case multiple endpoints receive
871 * the same call.
872 *
873 * RTP optimization: if we find a matching media channel expectation
874 * and both the expectation and this connection are SNATed, we assume
875 * both sides can reach each other directly and use the final
876 * destination address from the expectation. We still need to keep
877 * the NATed expectations for media that might arrive from the
878 * outside, and additionally need to expect the direct RTP stream
879 * in case it passes through us even without NAT.
880 */
881 memset(&tuple, 0, sizeof(tuple));
882 if (saddr)
883 tuple.src.u3 = *saddr;
884 tuple.src.l3num = nf_ct_l3num(ct);
885 tuple.dst.protonum = IPPROTO_UDP;
886 tuple.dst.u3 = *daddr;
887 tuple.dst.u.udp.port = port;
888
889 rcu_read_lock();
890 do {
891 exp = __nf_ct_expect_find(net, nf_ct_zone(ct), &tuple);
892
893 if (!exp || exp->master == ct ||
894 nfct_help(exp->master)->helper != nfct_help(ct)->helper ||
895 exp->class != class)
896 break;
897 #ifdef CONFIG_NF_NAT_NEEDED
898 if (!direct_rtp &&
899 (!nf_inet_addr_cmp(&exp->saved_addr, &exp->tuple.dst.u3) ||
900 exp->saved_proto.udp.port != exp->tuple.dst.u.udp.port) &&
901 ct->status & IPS_NAT_MASK) {
902 *daddr = exp->saved_addr;
903 tuple.dst.u3 = exp->saved_addr;
904 tuple.dst.u.udp.port = exp->saved_proto.udp.port;
905 direct_rtp = 1;
906 } else
907 #endif
908 skip_expect = 1;
909 } while (!skip_expect);
910
911 base_port = ntohs(tuple.dst.u.udp.port) & ~1;
912 rtp_port = htons(base_port);
913 rtcp_port = htons(base_port + 1);
914
915 if (direct_rtp) {
916 hooks = rcu_dereference(nf_nat_sip_hooks);
917 if (hooks &&
918 !hooks->sdp_port(skb, protoff, dataoff, dptr, datalen,
919 mediaoff, medialen, ntohs(rtp_port)))
920 goto err1;
921 }
922
923 if (skip_expect) {
924 rcu_read_unlock();
925 return NF_ACCEPT;
926 }
927
928 rtp_exp = nf_ct_expect_alloc(ct);
929 if (rtp_exp == NULL)
930 goto err1;
931 nf_ct_expect_init(rtp_exp, class, nf_ct_l3num(ct), saddr, daddr,
932 IPPROTO_UDP, NULL, &rtp_port);
933
934 rtcp_exp = nf_ct_expect_alloc(ct);
935 if (rtcp_exp == NULL)
936 goto err2;
937 nf_ct_expect_init(rtcp_exp, class, nf_ct_l3num(ct), saddr, daddr,
938 IPPROTO_UDP, NULL, &rtcp_port);
939
940 hooks = rcu_dereference(nf_nat_sip_hooks);
941 if (hooks && ct->status & IPS_NAT_MASK && !direct_rtp)
942 ret = hooks->sdp_media(skb, protoff, dataoff, dptr,
943 datalen, rtp_exp, rtcp_exp,
944 mediaoff, medialen, daddr);
945 else {
946 if (nf_ct_expect_related(rtp_exp) == 0) {
947 if (nf_ct_expect_related(rtcp_exp) != 0)
948 nf_ct_unexpect_related(rtp_exp);
949 else
950 ret = NF_ACCEPT;
951 }
952 }
953 nf_ct_expect_put(rtcp_exp);
954 err2:
955 nf_ct_expect_put(rtp_exp);
956 err1:
957 rcu_read_unlock();
958 return ret;
959 }
960
961 static const struct sdp_media_type sdp_media_types[] = {
962 SDP_MEDIA_TYPE("audio ", SIP_EXPECT_AUDIO),
963 SDP_MEDIA_TYPE("video ", SIP_EXPECT_VIDEO),
964 SDP_MEDIA_TYPE("image ", SIP_EXPECT_IMAGE),
965 };
966
967 static const struct sdp_media_type *sdp_media_type(const char *dptr,
968 unsigned int matchoff,
969 unsigned int matchlen)
970 {
971 const struct sdp_media_type *t;
972 unsigned int i;
973
974 for (i = 0; i < ARRAY_SIZE(sdp_media_types); i++) {
975 t = &sdp_media_types[i];
976 if (matchlen < t->len ||
977 strncmp(dptr + matchoff, t->name, t->len))
978 continue;
979 return t;
980 }
981 return NULL;
982 }
983
984 static int process_sdp(struct sk_buff *skb, unsigned int protoff,
985 unsigned int dataoff,
986 const char **dptr, unsigned int *datalen,
987 unsigned int cseq)
988 {
989 enum ip_conntrack_info ctinfo;
990 struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
991 unsigned int matchoff, matchlen;
992 unsigned int mediaoff, medialen;
993 unsigned int sdpoff;
994 unsigned int caddr_len, maddr_len;
995 unsigned int i;
996 union nf_inet_addr caddr, maddr, rtp_addr;
997 const struct nf_nat_sip_hooks *hooks;
998 unsigned int port;
999 const struct sdp_media_type *t;
1000 int ret = NF_ACCEPT;
1001
1002 hooks = rcu_dereference(nf_nat_sip_hooks);
1003
1004 /* Find beginning of session description */
1005 if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen,
1006 SDP_HDR_VERSION, SDP_HDR_UNSPEC,
1007 &matchoff, &matchlen) <= 0)
1008 return NF_ACCEPT;
1009 sdpoff = matchoff;
1010
1011 /* The connection information is contained in the session description
1012 * and/or once per media description. The first media description marks
1013 * the end of the session description. */
1014 caddr_len = 0;
1015 if (ct_sip_parse_sdp_addr(ct, *dptr, sdpoff, *datalen,
1016 SDP_HDR_CONNECTION, SDP_HDR_MEDIA,
1017 &matchoff, &matchlen, &caddr) > 0)
1018 caddr_len = matchlen;
1019
1020 mediaoff = sdpoff;
1021 for (i = 0; i < ARRAY_SIZE(sdp_media_types); ) {
1022 if (ct_sip_get_sdp_header(ct, *dptr, mediaoff, *datalen,
1023 SDP_HDR_MEDIA, SDP_HDR_UNSPEC,
1024 &mediaoff, &medialen) <= 0)
1025 break;
1026
1027 /* Get media type and port number. A media port value of zero
1028 * indicates an inactive stream. */
1029 t = sdp_media_type(*dptr, mediaoff, medialen);
1030 if (!t) {
1031 mediaoff += medialen;
1032 continue;
1033 }
1034 mediaoff += t->len;
1035 medialen -= t->len;
1036
1037 port = simple_strtoul(*dptr + mediaoff, NULL, 10);
1038 if (port == 0)
1039 continue;
1040 if (port < 1024 || port > 65535) {
1041 nf_ct_helper_log(skb, ct, "wrong port %u", port);
1042 return NF_DROP;
1043 }
1044
1045 /* The media description overrides the session description. */
1046 maddr_len = 0;
1047 if (ct_sip_parse_sdp_addr(ct, *dptr, mediaoff, *datalen,
1048 SDP_HDR_CONNECTION, SDP_HDR_MEDIA,
1049 &matchoff, &matchlen, &maddr) > 0) {
1050 maddr_len = matchlen;
1051 memcpy(&rtp_addr, &maddr, sizeof(rtp_addr));
1052 } else if (caddr_len)
1053 memcpy(&rtp_addr, &caddr, sizeof(rtp_addr));
1054 else {
1055 nf_ct_helper_log(skb, ct, "cannot parse SDP message");
1056 return NF_DROP;
1057 }
1058
1059 ret = set_expected_rtp_rtcp(skb, protoff, dataoff,
1060 dptr, datalen,
1061 &rtp_addr, htons(port), t->class,
1062 mediaoff, medialen);
1063 if (ret != NF_ACCEPT) {
1064 nf_ct_helper_log(skb, ct,
1065 "cannot add expectation for voice");
1066 return ret;
1067 }
1068
1069 /* Update media connection address if present */
1070 if (maddr_len && hooks && ct->status & IPS_NAT_MASK) {
1071 ret = hooks->sdp_addr(skb, protoff, dataoff,
1072 dptr, datalen, mediaoff,
1073 SDP_HDR_CONNECTION,
1074 SDP_HDR_MEDIA,
1075 &rtp_addr);
1076 if (ret != NF_ACCEPT) {
1077 nf_ct_helper_log(skb, ct, "cannot mangle SDP");
1078 return ret;
1079 }
1080 }
1081 i++;
1082 }
1083
1084 /* Update session connection and owner addresses */
1085 hooks = rcu_dereference(nf_nat_sip_hooks);
1086 if (hooks && ct->status & IPS_NAT_MASK)
1087 ret = hooks->sdp_session(skb, protoff, dataoff,
1088 dptr, datalen, sdpoff,
1089 &rtp_addr);
1090
1091 return ret;
1092 }
1093 static int process_invite_response(struct sk_buff *skb, unsigned int protoff,
1094 unsigned int dataoff,
1095 const char **dptr, unsigned int *datalen,
1096 unsigned int cseq, unsigned int code)
1097 {
1098 enum ip_conntrack_info ctinfo;
1099 struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1100 struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1101
1102 if ((code >= 100 && code <= 199) ||
1103 (code >= 200 && code <= 299))
1104 return process_sdp(skb, protoff, dataoff, dptr, datalen, cseq);
1105 else if (ct_sip_info->invite_cseq == cseq)
1106 flush_expectations(ct, true);
1107 return NF_ACCEPT;
1108 }
1109
1110 static int process_update_response(struct sk_buff *skb, unsigned int protoff,
1111 unsigned int dataoff,
1112 const char **dptr, unsigned int *datalen,
1113 unsigned int cseq, unsigned int code)
1114 {
1115 enum ip_conntrack_info ctinfo;
1116 struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1117 struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1118
1119 if ((code >= 100 && code <= 199) ||
1120 (code >= 200 && code <= 299))
1121 return process_sdp(skb, protoff, dataoff, dptr, datalen, cseq);
1122 else if (ct_sip_info->invite_cseq == cseq)
1123 flush_expectations(ct, true);
1124 return NF_ACCEPT;
1125 }
1126
1127 static int process_prack_response(struct sk_buff *skb, unsigned int protoff,
1128 unsigned int dataoff,
1129 const char **dptr, unsigned int *datalen,
1130 unsigned int cseq, unsigned int code)
1131 {
1132 enum ip_conntrack_info ctinfo;
1133 struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1134 struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1135
1136 if ((code >= 100 && code <= 199) ||
1137 (code >= 200 && code <= 299))
1138 return process_sdp(skb, protoff, dataoff, dptr, datalen, cseq);
1139 else if (ct_sip_info->invite_cseq == cseq)
1140 flush_expectations(ct, true);
1141 return NF_ACCEPT;
1142 }
1143
1144 static int process_invite_request(struct sk_buff *skb, unsigned int protoff,
1145 unsigned int dataoff,
1146 const char **dptr, unsigned int *datalen,
1147 unsigned int cseq)
1148 {
1149 enum ip_conntrack_info ctinfo;
1150 struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1151 struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1152 unsigned int ret;
1153
1154 flush_expectations(ct, true);
1155 ret = process_sdp(skb, protoff, dataoff, dptr, datalen, cseq);
1156 if (ret == NF_ACCEPT)
1157 ct_sip_info->invite_cseq = cseq;
1158 return ret;
1159 }
1160
1161 static int process_bye_request(struct sk_buff *skb, unsigned int protoff,
1162 unsigned int dataoff,
1163 const char **dptr, unsigned int *datalen,
1164 unsigned int cseq)
1165 {
1166 enum ip_conntrack_info ctinfo;
1167 struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1168
1169 flush_expectations(ct, true);
1170 return NF_ACCEPT;
1171 }
1172
1173 /* Parse a REGISTER request and create a permanent expectation for incoming
1174 * signalling connections. The expectation is marked inactive and is activated
1175 * when receiving a response indicating success from the registrar.
1176 */
1177 static int process_register_request(struct sk_buff *skb, unsigned int protoff,
1178 unsigned int dataoff,
1179 const char **dptr, unsigned int *datalen,
1180 unsigned int cseq)
1181 {
1182 enum ip_conntrack_info ctinfo;
1183 struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1184 struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1185 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
1186 unsigned int matchoff, matchlen;
1187 struct nf_conntrack_expect *exp;
1188 union nf_inet_addr *saddr, daddr;
1189 const struct nf_nat_sip_hooks *hooks;
1190 __be16 port;
1191 u8 proto;
1192 unsigned int expires = 0;
1193 int ret;
1194
1195 /* Expected connections can not register again. */
1196 if (ct->status & IPS_EXPECTED)
1197 return NF_ACCEPT;
1198
1199 /* We must check the expiration time: a value of zero signals the
1200 * registrar to release the binding. We'll remove our expectation
1201 * when receiving the new bindings in the response, but we don't
1202 * want to create new ones.
1203 *
1204 * The expiration time may be contained in Expires: header, the
1205 * Contact: header parameters or the URI parameters.
1206 */
1207 if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_EXPIRES,
1208 &matchoff, &matchlen) > 0)
1209 expires = simple_strtoul(*dptr + matchoff, NULL, 10);
1210
1211 ret = ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen,
1212 SIP_HDR_CONTACT, NULL,
1213 &matchoff, &matchlen, &daddr, &port);
1214 if (ret < 0) {
1215 nf_ct_helper_log(skb, ct, "cannot parse contact");
1216 return NF_DROP;
1217 } else if (ret == 0)
1218 return NF_ACCEPT;
1219
1220 /* We don't support third-party registrations */
1221 if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3, &daddr))
1222 return NF_ACCEPT;
1223
1224 if (ct_sip_parse_transport(ct, *dptr, matchoff + matchlen, *datalen,
1225 &proto) == 0)
1226 return NF_ACCEPT;
1227
1228 if (ct_sip_parse_numerical_param(ct, *dptr,
1229 matchoff + matchlen, *datalen,
1230 "expires=", NULL, NULL, &expires) < 0) {
1231 nf_ct_helper_log(skb, ct, "cannot parse expires");
1232 return NF_DROP;
1233 }
1234
1235 if (expires == 0) {
1236 ret = NF_ACCEPT;
1237 goto store_cseq;
1238 }
1239
1240 exp = nf_ct_expect_alloc(ct);
1241 if (!exp) {
1242 nf_ct_helper_log(skb, ct, "cannot alloc expectation");
1243 return NF_DROP;
1244 }
1245
1246 saddr = NULL;
1247 if (sip_direct_signalling)
1248 saddr = &ct->tuplehash[!dir].tuple.src.u3;
1249
1250 nf_ct_expect_init(exp, SIP_EXPECT_SIGNALLING, nf_ct_l3num(ct),
1251 saddr, &daddr, proto, NULL, &port);
1252 exp->timeout.expires = sip_timeout * HZ;
1253 exp->helper = nfct_help(ct)->helper;
1254 exp->flags = NF_CT_EXPECT_PERMANENT | NF_CT_EXPECT_INACTIVE;
1255
1256 hooks = rcu_dereference(nf_nat_sip_hooks);
1257 if (hooks && ct->status & IPS_NAT_MASK)
1258 ret = hooks->expect(skb, protoff, dataoff, dptr, datalen,
1259 exp, matchoff, matchlen);
1260 else {
1261 if (nf_ct_expect_related(exp) != 0) {
1262 nf_ct_helper_log(skb, ct, "cannot add expectation");
1263 ret = NF_DROP;
1264 } else
1265 ret = NF_ACCEPT;
1266 }
1267 nf_ct_expect_put(exp);
1268
1269 store_cseq:
1270 if (ret == NF_ACCEPT)
1271 ct_sip_info->register_cseq = cseq;
1272 return ret;
1273 }
1274
1275 static int process_register_response(struct sk_buff *skb, unsigned int protoff,
1276 unsigned int dataoff,
1277 const char **dptr, unsigned int *datalen,
1278 unsigned int cseq, unsigned int code)
1279 {
1280 enum ip_conntrack_info ctinfo;
1281 struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1282 struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1283 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
1284 union nf_inet_addr addr;
1285 __be16 port;
1286 u8 proto;
1287 unsigned int matchoff, matchlen, coff = 0;
1288 unsigned int expires = 0;
1289 int in_contact = 0, ret;
1290
1291 /* According to RFC 3261, "UAs MUST NOT send a new registration until
1292 * they have received a final response from the registrar for the
1293 * previous one or the previous REGISTER request has timed out".
1294 *
1295 * However, some servers fail to detect retransmissions and send late
1296 * responses, so we store the sequence number of the last valid
1297 * request and compare it here.
1298 */
1299 if (ct_sip_info->register_cseq != cseq)
1300 return NF_ACCEPT;
1301
1302 if (code >= 100 && code <= 199)
1303 return NF_ACCEPT;
1304 if (code < 200 || code > 299)
1305 goto flush;
1306
1307 if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_EXPIRES,
1308 &matchoff, &matchlen) > 0)
1309 expires = simple_strtoul(*dptr + matchoff, NULL, 10);
1310
1311 while (1) {
1312 unsigned int c_expires = expires;
1313
1314 ret = ct_sip_parse_header_uri(ct, *dptr, &coff, *datalen,
1315 SIP_HDR_CONTACT, &in_contact,
1316 &matchoff, &matchlen,
1317 &addr, &port);
1318 if (ret < 0) {
1319 nf_ct_helper_log(skb, ct, "cannot parse contact");
1320 return NF_DROP;
1321 } else if (ret == 0)
1322 break;
1323
1324 /* We don't support third-party registrations */
1325 if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3, &addr))
1326 continue;
1327
1328 if (ct_sip_parse_transport(ct, *dptr, matchoff + matchlen,
1329 *datalen, &proto) == 0)
1330 continue;
1331
1332 ret = ct_sip_parse_numerical_param(ct, *dptr,
1333 matchoff + matchlen,
1334 *datalen, "expires=",
1335 NULL, NULL, &c_expires);
1336 if (ret < 0) {
1337 nf_ct_helper_log(skb, ct, "cannot parse expires");
1338 return NF_DROP;
1339 }
1340 if (c_expires == 0)
1341 break;
1342 if (refresh_signalling_expectation(ct, &addr, proto, port,
1343 c_expires))
1344 return NF_ACCEPT;
1345 }
1346
1347 flush:
1348 flush_expectations(ct, false);
1349 return NF_ACCEPT;
1350 }
1351
1352 static const struct sip_handler sip_handlers[] = {
1353 SIP_HANDLER("INVITE", process_invite_request, process_invite_response),
1354 SIP_HANDLER("UPDATE", process_sdp, process_update_response),
1355 SIP_HANDLER("ACK", process_sdp, NULL),
1356 SIP_HANDLER("PRACK", process_sdp, process_prack_response),
1357 SIP_HANDLER("BYE", process_bye_request, NULL),
1358 SIP_HANDLER("REGISTER", process_register_request, process_register_response),
1359 };
1360
1361 static int process_sip_response(struct sk_buff *skb, unsigned int protoff,
1362 unsigned int dataoff,
1363 const char **dptr, unsigned int *datalen)
1364 {
1365 enum ip_conntrack_info ctinfo;
1366 struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1367 unsigned int matchoff, matchlen, matchend;
1368 unsigned int code, cseq, i;
1369
1370 if (*datalen < strlen("SIP/2.0 200"))
1371 return NF_ACCEPT;
1372 code = simple_strtoul(*dptr + strlen("SIP/2.0 "), NULL, 10);
1373 if (!code) {
1374 nf_ct_helper_log(skb, ct, "cannot get code");
1375 return NF_DROP;
1376 }
1377
1378 if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CSEQ,
1379 &matchoff, &matchlen) <= 0) {
1380 nf_ct_helper_log(skb, ct, "cannot parse cseq");
1381 return NF_DROP;
1382 }
1383 cseq = simple_strtoul(*dptr + matchoff, NULL, 10);
1384 if (!cseq && *(*dptr + matchoff) != '') {
1385 nf_ct_helper_log(skb, ct, "cannot get cseq");
1386 return NF_DROP;
1387 }
1388 matchend = matchoff + matchlen + 1;
1389
1390 for (i = 0; i < ARRAY_SIZE(sip_handlers); i++) {
1391 const struct sip_handler *handler;
1392
1393 handler = &sip_handlers[i];
1394 if (handler->response == NULL)
1395 continue;
1396 if (*datalen < matchend + handler->len ||
1397 strncasecmp(*dptr + matchend, handler->method, handler->len))
1398 continue;
1399 return handler->response(skb, protoff, dataoff, dptr, datalen,
1400 cseq, code);
1401 }
1402 return NF_ACCEPT;
1403 }
1404
1405 static int process_sip_request(struct sk_buff *skb, unsigned int protoff,
1406 unsigned int dataoff,
1407 const char **dptr, unsigned int *datalen)
1408 {
1409 enum ip_conntrack_info ctinfo;
1410 struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1411 struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1412 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
1413 unsigned int matchoff, matchlen;
1414 unsigned int cseq, i;
1415 union nf_inet_addr addr;
1416 __be16 port;
1417
1418 /* Many Cisco IP phones use a high source port for SIP requests, but
1419 * listen for the response on port 5060. If we are the local
1420 * router for one of these phones, save the port number from the
1421 * Via: header so that nf_nat_sip can redirect the responses to
1422 * the correct port.
1423 */
1424 if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen,
1425 SIP_HDR_VIA_UDP, NULL, &matchoff,
1426 &matchlen, &addr, &port) > 0 &&
1427 port != ct->tuplehash[dir].tuple.src.u.udp.port &&
1428 nf_inet_addr_cmp(&addr, &ct->tuplehash[dir].tuple.src.u3))
1429 ct_sip_info->forced_dport = port;
1430
1431 for (i = 0; i < ARRAY_SIZE(sip_handlers); i++) {
1432 const struct sip_handler *handler;
1433
1434 handler = &sip_handlers[i];
1435 if (handler->request == NULL)
1436 continue;
1437 if (*datalen < handler->len + 2 ||
1438 strncasecmp(*dptr, handler->method, handler->len))
1439 continue;
1440 if ((*dptr)[handler->len] != ' ' ||
1441 !isalpha((*dptr)[handler->len+1]))
1442 continue;
1443
1444 if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CSEQ,
1445 &matchoff, &matchlen) <= 0) {
1446 nf_ct_helper_log(skb, ct, "cannot parse cseq");
1447 return NF_DROP;
1448 }
1449 cseq = simple_strtoul(*dptr + matchoff, NULL, 10);
1450 if (!cseq && *(*dptr + matchoff) != '') {
1451 nf_ct_helper_log(skb, ct, "cannot get cseq");
1452 return NF_DROP;
1453 }
1454
1455 return handler->request(skb, protoff, dataoff, dptr, datalen,
1456 cseq);
1457 }
1458 return NF_ACCEPT;
1459 }
1460
1461 static int process_sip_msg(struct sk_buff *skb, struct nf_conn *ct,
1462 unsigned int protoff, unsigned int dataoff,
1463 const char **dptr, unsigned int *datalen)
1464 {
1465 const struct nf_nat_sip_hooks *hooks;
1466 int ret;
1467
1468 if (strncasecmp(*dptr, "SIP/2.0 ", strlen("SIP/2.0 ")) != 0)
1469 ret = process_sip_request(skb, protoff, dataoff, dptr, datalen);
1470 else
1471 ret = process_sip_response(skb, protoff, dataoff, dptr, datalen);
1472
1473 if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) {
1474 hooks = rcu_dereference(nf_nat_sip_hooks);
1475 if (hooks && !hooks->msg(skb, protoff, dataoff,
1476 dptr, datalen)) {
1477 nf_ct_helper_log(skb, ct, "cannot NAT SIP message");
1478 ret = NF_DROP;
1479 }
1480 }
1481
1482 return ret;
1483 }
1484
1485 static int sip_help_tcp(struct sk_buff *skb, unsigned int protoff,
1486 struct nf_conn *ct, enum ip_conntrack_info ctinfo)
1487 {
1488 struct tcphdr *th, _tcph;
1489 unsigned int dataoff, datalen;
1490 unsigned int matchoff, matchlen, clen;
1491 unsigned int msglen, origlen;
1492 const char *dptr, *end;
1493 s16 diff, tdiff = 0;
1494 int ret = NF_ACCEPT;
1495 bool term;
1496
1497 if (ctinfo != IP_CT_ESTABLISHED &&
1498 ctinfo != IP_CT_ESTABLISHED_REPLY)
1499 return NF_ACCEPT;
1500
1501 /* No Data ? */
1502 th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
1503 if (th == NULL)
1504 return NF_ACCEPT;
1505 dataoff = protoff + th->doff * 4;
1506 if (dataoff >= skb->len)
1507 return NF_ACCEPT;
1508
1509 nf_ct_refresh(ct, skb, sip_timeout * HZ);
1510
1511 if (unlikely(skb_linearize(skb)))
1512 return NF_DROP;
1513
1514 dptr = skb->data + dataoff;
1515 datalen = skb->len - dataoff;
1516 if (datalen < strlen("SIP/2.0 200"))
1517 return NF_ACCEPT;
1518
1519 while (1) {
1520 if (ct_sip_get_header(ct, dptr, 0, datalen,
1521 SIP_HDR_CONTENT_LENGTH,
1522 &matchoff, &matchlen) <= 0)
1523 break;
1524
1525 clen = simple_strtoul(dptr + matchoff, (char **)&end, 10);
1526 if (dptr + matchoff == end)
1527 break;
1528
1529 term = false;
1530 for (; end + strlen("\r\n\r\n") <= dptr + datalen; end++) {
1531 if (end[0] == '\r' && end[1] == '\n' &&
1532 end[2] == '\r' && end[3] == '\n') {
1533 term = true;
1534 break;
1535 }
1536 }
1537 if (!term)
1538 break;
1539 end += strlen("\r\n\r\n") + clen;
1540
1541 msglen = origlen = end - dptr;
1542 if (msglen > datalen)
1543 return NF_ACCEPT;
1544
1545 ret = process_sip_msg(skb, ct, protoff, dataoff,
1546 &dptr, &msglen);
1547 /* process_sip_* functions report why this packet is dropped */
1548 if (ret != NF_ACCEPT)
1549 break;
1550 diff = msglen - origlen;
1551 tdiff += diff;
1552
1553 dataoff += msglen;
1554 dptr += msglen;
1555 datalen = datalen + diff - msglen;
1556 }
1557
1558 if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) {
1559 const struct nf_nat_sip_hooks *hooks;
1560
1561 hooks = rcu_dereference(nf_nat_sip_hooks);
1562 if (hooks)
1563 hooks->seq_adjust(skb, protoff, tdiff);
1564 }
1565
1566 return ret;
1567 }
1568
1569 static int sip_help_udp(struct sk_buff *skb, unsigned int protoff,
1570 struct nf_conn *ct, enum ip_conntrack_info ctinfo)
1571 {
1572 unsigned int dataoff, datalen;
1573 const char *dptr;
1574
1575 /* No Data ? */
1576 dataoff = protoff + sizeof(struct udphdr);
1577 if (dataoff >= skb->len)
1578 return NF_ACCEPT;
1579
1580 nf_ct_refresh(ct, skb, sip_timeout * HZ);
1581
1582 if (unlikely(skb_linearize(skb)))
1583 return NF_DROP;
1584
1585 dptr = skb->data + dataoff;
1586 datalen = skb->len - dataoff;
1587 if (datalen < strlen("SIP/2.0 200"))
1588 return NF_ACCEPT;
1589
1590 return process_sip_msg(skb, ct, protoff, dataoff, &dptr, &datalen);
1591 }
1592
1593 static struct nf_conntrack_helper sip[MAX_PORTS * 4] __read_mostly;
1594
1595 static const struct nf_conntrack_expect_policy sip_exp_policy[SIP_EXPECT_MAX + 1] = {
1596 [SIP_EXPECT_SIGNALLING] = {
1597 .name = "signalling",
1598 .max_expected = 1,
1599 .timeout = 3 * 60,
1600 },
1601 [SIP_EXPECT_AUDIO] = {
1602 .name = "audio",
1603 .max_expected = 2 * IP_CT_DIR_MAX,
1604 .timeout = 3 * 60,
1605 },
1606 [SIP_EXPECT_VIDEO] = {
1607 .name = "video",
1608 .max_expected = 2 * IP_CT_DIR_MAX,
1609 .timeout = 3 * 60,
1610 },
1611 [SIP_EXPECT_IMAGE] = {
1612 .name = "image",
1613 .max_expected = IP_CT_DIR_MAX,
1614 .timeout = 3 * 60,
1615 },
1616 };
1617
1618 static void nf_conntrack_sip_fini(void)
1619 {
1620 nf_conntrack_helpers_unregister(sip, ports_c * 4);
1621 }
1622
1623 static int __init nf_conntrack_sip_init(void)
1624 {
1625 int i, ret;
1626
1627 if (ports_c == 0)
1628 ports[ports_c++] = SIP_PORT;
1629
1630 for (i = 0; i < ports_c; i++) {
1631 nf_ct_helper_init(&sip[4 * i], AF_INET, IPPROTO_UDP, "sip",
1632 SIP_PORT, ports[i], i, sip_exp_policy,
1633 SIP_EXPECT_MAX,
1634 sizeof(struct nf_ct_sip_master), sip_help_udp,
1635 NULL, THIS_MODULE);
1636 nf_ct_helper_init(&sip[4 * i + 1], AF_INET, IPPROTO_TCP, "sip",
1637 SIP_PORT, ports[i], i, sip_exp_policy,
1638 SIP_EXPECT_MAX,
1639 sizeof(struct nf_ct_sip_master), sip_help_tcp,
1640 NULL, THIS_MODULE);
1641 nf_ct_helper_init(&sip[4 * i + 2], AF_INET6, IPPROTO_UDP, "sip",
1642 SIP_PORT, ports[i], i, sip_exp_policy,
1643 SIP_EXPECT_MAX,
1644 sizeof(struct nf_ct_sip_master), sip_help_udp,
1645 NULL, THIS_MODULE);
1646 nf_ct_helper_init(&sip[4 * i + 3], AF_INET6, IPPROTO_TCP, "sip",
1647 SIP_PORT, ports[i], i, sip_exp_policy,
1648 SIP_EXPECT_MAX,
1649 sizeof(struct nf_ct_sip_master), sip_help_tcp,
1650 NULL, THIS_MODULE);
1651 }
1652
1653 ret = nf_conntrack_helpers_register(sip, ports_c * 4);
1654 if (ret < 0) {
1655 pr_err("failed to register helpers\n");
1656 return ret;
1657 }
1658 return 0;
1659 }
1660
1661 module_init(nf_conntrack_sip_init);
1662 module_exit(nf_conntrack_sip_fini);
1663
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