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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 | #include <linux/module.h> | |
14 | #include <linux/ctype.h> | |
15 | #include <linux/skbuff.h> | |
16 | #include <linux/inet.h> | |
17 | #include <linux/in.h> | |
18 | #include <linux/udp.h> | |
19 | #include <linux/netfilter.h> | |
20 | ||
21 | #include <net/netfilter/nf_conntrack.h> | |
22 | #include <net/netfilter/nf_conntrack_core.h> | |
23 | #include <net/netfilter/nf_conntrack_expect.h> | |
24 | #include <net/netfilter/nf_conntrack_helper.h> | |
25 | #include <linux/netfilter/nf_conntrack_sip.h> | |
26 | ||
27 | MODULE_LICENSE("GPL"); | |
28 | MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>"); | |
29 | MODULE_DESCRIPTION("SIP connection tracking helper"); | |
30 | MODULE_ALIAS("ip_conntrack_sip"); | |
31 | MODULE_ALIAS_NFCT_HELPER("sip"); | |
32 | ||
33 | #define MAX_PORTS 8 | |
34 | static unsigned short ports[MAX_PORTS]; | |
35 | static unsigned int ports_c; | |
36 | module_param_array(ports, ushort, &ports_c, 0400); | |
37 | MODULE_PARM_DESC(ports, "port numbers of SIP servers"); | |
38 | ||
39 | static unsigned int sip_timeout __read_mostly = SIP_TIMEOUT; | |
40 | module_param(sip_timeout, uint, 0600); | |
41 | MODULE_PARM_DESC(sip_timeout, "timeout for the master SIP session"); | |
42 | ||
43 | static int sip_direct_signalling __read_mostly = 1; | |
44 | module_param(sip_direct_signalling, int, 0600); | |
45 | MODULE_PARM_DESC(sip_direct_signalling, "expect incoming calls from registrar " | |
46 | "only (default 1)"); | |
47 | ||
48 | static int sip_direct_media __read_mostly = 1; | |
49 | module_param(sip_direct_media, int, 0600); | |
50 | MODULE_PARM_DESC(sip_direct_media, "Expect Media streams between signalling " | |
51 | "endpoints only (default 1)"); | |
52 | ||
53 | unsigned int (*nf_nat_sip_hook)(struct sk_buff *skb, unsigned int dataoff, | |
54 | const char **dptr, | |
55 | unsigned int *datalen) __read_mostly; | |
56 | EXPORT_SYMBOL_GPL(nf_nat_sip_hook); | |
57 | ||
58 | unsigned int (*nf_nat_sip_expect_hook)(struct sk_buff *skb, | |
59 | unsigned int dataoff, | |
60 | const char **dptr, | |
61 | unsigned int *datalen, | |
62 | struct nf_conntrack_expect *exp, | |
63 | unsigned int matchoff, | |
64 | unsigned int matchlen) __read_mostly; | |
65 | EXPORT_SYMBOL_GPL(nf_nat_sip_expect_hook); | |
66 | ||
67 | unsigned int (*nf_nat_sdp_addr_hook)(struct sk_buff *skb, unsigned int dataoff, | |
68 | const char **dptr, | |
69 | unsigned int *datalen, | |
70 | unsigned int sdpoff, | |
71 | enum sdp_header_types type, | |
72 | enum sdp_header_types term, | |
73 | const union nf_inet_addr *addr) | |
74 | __read_mostly; | |
75 | EXPORT_SYMBOL_GPL(nf_nat_sdp_addr_hook); | |
76 | ||
77 | unsigned int (*nf_nat_sdp_port_hook)(struct sk_buff *skb, unsigned int dataoff, | |
78 | const char **dptr, | |
79 | unsigned int *datalen, | |
80 | unsigned int matchoff, | |
81 | unsigned int matchlen, | |
82 | u_int16_t port) __read_mostly; | |
83 | EXPORT_SYMBOL_GPL(nf_nat_sdp_port_hook); | |
84 | ||
85 | unsigned int (*nf_nat_sdp_session_hook)(struct sk_buff *skb, | |
86 | unsigned int dataoff, | |
87 | const char **dptr, | |
88 | unsigned int *datalen, | |
89 | unsigned int sdpoff, | |
90 | const union nf_inet_addr *addr) | |
91 | __read_mostly; | |
92 | EXPORT_SYMBOL_GPL(nf_nat_sdp_session_hook); | |
93 | ||
94 | unsigned int (*nf_nat_sdp_media_hook)(struct sk_buff *skb, unsigned int dataoff, | |
95 | const char **dptr, | |
96 | unsigned int *datalen, | |
97 | struct nf_conntrack_expect *rtp_exp, | |
98 | struct nf_conntrack_expect *rtcp_exp, | |
99 | unsigned int mediaoff, | |
100 | unsigned int medialen, | |
101 | union nf_inet_addr *rtp_addr) | |
102 | __read_mostly; | |
103 | EXPORT_SYMBOL_GPL(nf_nat_sdp_media_hook); | |
104 | ||
105 | static int string_len(const struct nf_conn *ct, const char *dptr, | |
106 | const char *limit, int *shift) | |
107 | { | |
108 | int len = 0; | |
109 | ||
110 | while (dptr < limit && isalpha(*dptr)) { | |
111 | dptr++; | |
112 | len++; | |
113 | } | |
114 | return len; | |
115 | } | |
116 | ||
117 | static int digits_len(const struct nf_conn *ct, const char *dptr, | |
118 | const char *limit, int *shift) | |
119 | { | |
120 | int len = 0; | |
121 | while (dptr < limit && isdigit(*dptr)) { | |
122 | dptr++; | |
123 | len++; | |
124 | } | |
125 | return len; | |
126 | } | |
127 | ||
128 | /* get media type + port length */ | |
129 | static int media_len(const struct nf_conn *ct, const char *dptr, | |
130 | const char *limit, int *shift) | |
131 | { | |
132 | int len = string_len(ct, dptr, limit, shift); | |
133 | ||
134 | dptr += len; | |
135 | if (dptr >= limit || *dptr != ' ') | |
136 | return 0; | |
137 | len++; | |
138 | dptr++; | |
139 | ||
140 | return len + digits_len(ct, dptr, limit, shift); | |
141 | } | |
142 | ||
143 | static int parse_addr(const struct nf_conn *ct, const char *cp, | |
144 | const char **endp, union nf_inet_addr *addr, | |
145 | const char *limit) | |
146 | { | |
147 | const char *end; | |
148 | int ret = 0; | |
149 | ||
150 | memset(addr, 0, sizeof(*addr)); | |
151 | switch (nf_ct_l3num(ct)) { | |
152 | case AF_INET: | |
153 | ret = in4_pton(cp, limit - cp, (u8 *)&addr->ip, -1, &end); | |
154 | break; | |
155 | case AF_INET6: | |
156 | ret = in6_pton(cp, limit - cp, (u8 *)&addr->ip6, -1, &end); | |
157 | break; | |
158 | default: | |
159 | BUG(); | |
160 | } | |
161 | ||
162 | if (ret == 0 || end == cp) | |
163 | return 0; | |
164 | if (endp) | |
165 | *endp = end; | |
166 | return 1; | |
167 | } | |
168 | ||
169 | /* skip ip address. returns its length. */ | |
170 | static int epaddr_len(const struct nf_conn *ct, const char *dptr, | |
171 | const char *limit, int *shift) | |
172 | { | |
173 | union nf_inet_addr addr; | |
174 | const char *aux = dptr; | |
175 | ||
176 | if (!parse_addr(ct, dptr, &dptr, &addr, limit)) { | |
177 | pr_debug("ip: %s parse failed.!\n", dptr); | |
178 | return 0; | |
179 | } | |
180 | ||
181 | /* Port number */ | |
182 | if (*dptr == ':') { | |
183 | dptr++; | |
184 | dptr += digits_len(ct, dptr, limit, shift); | |
185 | } | |
186 | return dptr - aux; | |
187 | } | |
188 | ||
189 | /* get address length, skiping user info. */ | |
190 | static int skp_epaddr_len(const struct nf_conn *ct, const char *dptr, | |
191 | const char *limit, int *shift) | |
192 | { | |
193 | const char *start = dptr; | |
194 | int s = *shift; | |
195 | ||
196 | /* Search for @, but stop at the end of the line. | |
197 | * We are inside a sip: URI, so we don't need to worry about | |
198 | * continuation lines. */ | |
199 | while (dptr < limit && | |
200 | *dptr != '@' && *dptr != '\r' && *dptr != '\n') { | |
201 | (*shift)++; | |
202 | dptr++; | |
203 | } | |
204 | ||
205 | if (dptr < limit && *dptr == '@') { | |
206 | dptr++; | |
207 | (*shift)++; | |
208 | } else { | |
209 | dptr = start; | |
210 | *shift = s; | |
211 | } | |
212 | ||
213 | return epaddr_len(ct, dptr, limit, shift); | |
214 | } | |
215 | ||
216 | /* Parse a SIP request line of the form: | |
217 | * | |
218 | * Request-Line = Method SP Request-URI SP SIP-Version CRLF | |
219 | * | |
220 | * and return the offset and length of the address contained in the Request-URI. | |
221 | */ | |
222 | int ct_sip_parse_request(const struct nf_conn *ct, | |
223 | const char *dptr, unsigned int datalen, | |
224 | unsigned int *matchoff, unsigned int *matchlen, | |
225 | union nf_inet_addr *addr, __be16 *port) | |
226 | { | |
227 | const char *start = dptr, *limit = dptr + datalen, *end; | |
228 | unsigned int mlen; | |
229 | unsigned int p; | |
230 | int shift = 0; | |
231 | ||
232 | /* Skip method and following whitespace */ | |
233 | mlen = string_len(ct, dptr, limit, NULL); | |
234 | if (!mlen) | |
235 | return 0; | |
236 | dptr += mlen; | |
237 | if (++dptr >= limit) | |
238 | return 0; | |
239 | ||
240 | /* Find SIP URI */ | |
241 | for (; dptr < limit - strlen("sip:"); dptr++) { | |
242 | if (*dptr == '\r' || *dptr == '\n') | |
243 | return -1; | |
244 | if (strnicmp(dptr, "sip:", strlen("sip:")) == 0) { | |
245 | dptr += strlen("sip:"); | |
246 | break; | |
247 | } | |
248 | } | |
249 | if (!skp_epaddr_len(ct, dptr, limit, &shift)) | |
250 | return 0; | |
251 | dptr += shift; | |
252 | ||
253 | if (!parse_addr(ct, dptr, &end, addr, limit)) | |
254 | return -1; | |
255 | if (end < limit && *end == ':') { | |
256 | end++; | |
257 | p = simple_strtoul(end, (char **)&end, 10); | |
258 | if (p < 1024 || p > 65535) | |
259 | return -1; | |
260 | *port = htons(p); | |
261 | } else | |
262 | *port = htons(SIP_PORT); | |
263 | ||
264 | if (end == dptr) | |
265 | return 0; | |
266 | *matchoff = dptr - start; | |
267 | *matchlen = end - dptr; | |
268 | return 1; | |
269 | } | |
270 | EXPORT_SYMBOL_GPL(ct_sip_parse_request); | |
271 | ||
272 | /* SIP header parsing: SIP headers are located at the beginning of a line, but | |
273 | * may span several lines, in which case the continuation lines begin with a | |
274 | * whitespace character. RFC 2543 allows lines to be terminated with CR, LF or | |
275 | * CRLF, RFC 3261 allows only CRLF, we support both. | |
276 | * | |
277 | * Headers are followed by (optionally) whitespace, a colon, again (optionally) | |
278 | * whitespace and the values. Whitespace in this context means any amount of | |
279 | * tabs, spaces and continuation lines, which are treated as a single whitespace | |
280 | * character. | |
281 | * | |
282 | * Some headers may appear multiple times. A comma seperated list of values is | |
283 | * equivalent to multiple headers. | |
284 | */ | |
285 | static const struct sip_header ct_sip_hdrs[] = { | |
286 | [SIP_HDR_CSEQ] = SIP_HDR("CSeq", NULL, NULL, digits_len), | |
287 | [SIP_HDR_FROM] = SIP_HDR("From", "f", "sip:", skp_epaddr_len), | |
288 | [SIP_HDR_TO] = SIP_HDR("To", "t", "sip:", skp_epaddr_len), | |
289 | [SIP_HDR_CONTACT] = SIP_HDR("Contact", "m", "sip:", skp_epaddr_len), | |
290 | [SIP_HDR_VIA] = SIP_HDR("Via", "v", "UDP ", epaddr_len), | |
291 | [SIP_HDR_EXPIRES] = SIP_HDR("Expires", NULL, NULL, digits_len), | |
292 | [SIP_HDR_CONTENT_LENGTH] = SIP_HDR("Content-Length", "l", NULL, digits_len), | |
293 | }; | |
294 | ||
295 | static const char *sip_follow_continuation(const char *dptr, const char *limit) | |
296 | { | |
297 | /* Walk past newline */ | |
298 | if (++dptr >= limit) | |
299 | return NULL; | |
300 | ||
301 | /* Skip '\n' in CR LF */ | |
302 | if (*(dptr - 1) == '\r' && *dptr == '\n') { | |
303 | if (++dptr >= limit) | |
304 | return NULL; | |
305 | } | |
306 | ||
307 | /* Continuation line? */ | |
308 | if (*dptr != ' ' && *dptr != '\t') | |
309 | return NULL; | |
310 | ||
311 | /* skip leading whitespace */ | |
312 | for (; dptr < limit; dptr++) { | |
313 | if (*dptr != ' ' && *dptr != '\t') | |
314 | break; | |
315 | } | |
316 | return dptr; | |
317 | } | |
318 | ||
319 | static const char *sip_skip_whitespace(const char *dptr, const char *limit) | |
320 | { | |
321 | for (; dptr < limit; dptr++) { | |
322 | if (*dptr == ' ') | |
323 | continue; | |
324 | if (*dptr != '\r' && *dptr != '\n') | |
325 | break; | |
326 | dptr = sip_follow_continuation(dptr, limit); | |
327 | if (dptr == NULL) | |
328 | return NULL; | |
329 | } | |
330 | return dptr; | |
331 | } | |
332 | ||
333 | /* Search within a SIP header value, dealing with continuation lines */ | |
334 | static const char *ct_sip_header_search(const char *dptr, const char *limit, | |
335 | const char *needle, unsigned int len) | |
336 | { | |
337 | for (limit -= len; dptr < limit; dptr++) { | |
338 | if (*dptr == '\r' || *dptr == '\n') { | |
339 | dptr = sip_follow_continuation(dptr, limit); | |
340 | if (dptr == NULL) | |
341 | break; | |
342 | continue; | |
343 | } | |
344 | ||
345 | if (strnicmp(dptr, needle, len) == 0) | |
346 | return dptr; | |
347 | } | |
348 | return NULL; | |
349 | } | |
350 | ||
351 | int ct_sip_get_header(const struct nf_conn *ct, const char *dptr, | |
352 | unsigned int dataoff, unsigned int datalen, | |
353 | enum sip_header_types type, | |
354 | unsigned int *matchoff, unsigned int *matchlen) | |
355 | { | |
356 | const struct sip_header *hdr = &ct_sip_hdrs[type]; | |
357 | const char *start = dptr, *limit = dptr + datalen; | |
358 | int shift = 0; | |
359 | ||
360 | for (dptr += dataoff; dptr < limit; dptr++) { | |
361 | /* Find beginning of line */ | |
362 | if (*dptr != '\r' && *dptr != '\n') | |
363 | continue; | |
364 | if (++dptr >= limit) | |
365 | break; | |
366 | if (*(dptr - 1) == '\r' && *dptr == '\n') { | |
367 | if (++dptr >= limit) | |
368 | break; | |
369 | } | |
370 | ||
371 | /* Skip continuation lines */ | |
372 | if (*dptr == ' ' || *dptr == '\t') | |
373 | continue; | |
374 | ||
375 | /* Find header. Compact headers must be followed by a | |
376 | * non-alphabetic character to avoid mismatches. */ | |
377 | if (limit - dptr >= hdr->len && | |
378 | strnicmp(dptr, hdr->name, hdr->len) == 0) | |
379 | dptr += hdr->len; | |
380 | else if (hdr->cname && limit - dptr >= hdr->clen + 1 && | |
381 | strnicmp(dptr, hdr->cname, hdr->clen) == 0 && | |
382 | !isalpha(*(dptr + hdr->clen))) | |
383 | dptr += hdr->clen; | |
384 | else | |
385 | continue; | |
386 | ||
387 | /* Find and skip colon */ | |
388 | dptr = sip_skip_whitespace(dptr, limit); | |
389 | if (dptr == NULL) | |
390 | break; | |
391 | if (*dptr != ':' || ++dptr >= limit) | |
392 | break; | |
393 | ||
394 | /* Skip whitespace after colon */ | |
395 | dptr = sip_skip_whitespace(dptr, limit); | |
396 | if (dptr == NULL) | |
397 | break; | |
398 | ||
399 | *matchoff = dptr - start; | |
400 | if (hdr->search) { | |
401 | dptr = ct_sip_header_search(dptr, limit, hdr->search, | |
402 | hdr->slen); | |
403 | if (!dptr) | |
404 | return -1; | |
405 | dptr += hdr->slen; | |
406 | } | |
407 | ||
408 | *matchlen = hdr->match_len(ct, dptr, limit, &shift); | |
409 | if (!*matchlen) | |
410 | return -1; | |
411 | *matchoff = dptr - start + shift; | |
412 | return 1; | |
413 | } | |
414 | return 0; | |
415 | } | |
416 | EXPORT_SYMBOL_GPL(ct_sip_get_header); | |
417 | ||
418 | /* Get next header field in a list of comma seperated values */ | |
419 | static int ct_sip_next_header(const struct nf_conn *ct, const char *dptr, | |
420 | unsigned int dataoff, unsigned int datalen, | |
421 | enum sip_header_types type, | |
422 | unsigned int *matchoff, unsigned int *matchlen) | |
423 | { | |
424 | const struct sip_header *hdr = &ct_sip_hdrs[type]; | |
425 | const char *start = dptr, *limit = dptr + datalen; | |
426 | int shift = 0; | |
427 | ||
428 | dptr += dataoff; | |
429 | ||
430 | dptr = ct_sip_header_search(dptr, limit, ",", strlen(",")); | |
431 | if (!dptr) | |
432 | return 0; | |
433 | ||
434 | dptr = ct_sip_header_search(dptr, limit, hdr->search, hdr->slen); | |
435 | if (!dptr) | |
436 | return 0; | |
437 | dptr += hdr->slen; | |
438 | ||
439 | *matchoff = dptr - start; | |
440 | *matchlen = hdr->match_len(ct, dptr, limit, &shift); | |
441 | if (!*matchlen) | |
442 | return -1; | |
443 | *matchoff += shift; | |
444 | return 1; | |
445 | } | |
446 | ||
447 | /* Walk through headers until a parsable one is found or no header of the | |
448 | * given type is left. */ | |
449 | static int ct_sip_walk_headers(const struct nf_conn *ct, const char *dptr, | |
450 | unsigned int dataoff, unsigned int datalen, | |
451 | enum sip_header_types type, int *in_header, | |
452 | unsigned int *matchoff, unsigned int *matchlen) | |
453 | { | |
454 | int ret; | |
455 | ||
456 | if (in_header && *in_header) { | |
457 | while (1) { | |
458 | ret = ct_sip_next_header(ct, dptr, dataoff, datalen, | |
459 | type, matchoff, matchlen); | |
460 | if (ret > 0) | |
461 | return ret; | |
462 | if (ret == 0) | |
463 | break; | |
464 | dataoff += *matchoff; | |
465 | } | |
466 | *in_header = 0; | |
467 | } | |
468 | ||
469 | while (1) { | |
470 | ret = ct_sip_get_header(ct, dptr, dataoff, datalen, | |
471 | type, matchoff, matchlen); | |
472 | if (ret > 0) | |
473 | break; | |
474 | if (ret == 0) | |
475 | return ret; | |
476 | dataoff += *matchoff; | |
477 | } | |
478 | ||
479 | if (in_header) | |
480 | *in_header = 1; | |
481 | return 1; | |
482 | } | |
483 | ||
484 | /* Locate a SIP header, parse the URI and return the offset and length of | |
485 | * the address as well as the address and port themselves. A stream of | |
486 | * headers can be parsed by handing in a non-NULL datalen and in_header | |
487 | * pointer. | |
488 | */ | |
489 | int ct_sip_parse_header_uri(const struct nf_conn *ct, const char *dptr, | |
490 | unsigned int *dataoff, unsigned int datalen, | |
491 | enum sip_header_types type, int *in_header, | |
492 | unsigned int *matchoff, unsigned int *matchlen, | |
493 | union nf_inet_addr *addr, __be16 *port) | |
494 | { | |
495 | const char *c, *limit = dptr + datalen; | |
496 | unsigned int p; | |
497 | int ret; | |
498 | ||
499 | ret = ct_sip_walk_headers(ct, dptr, dataoff ? *dataoff : 0, datalen, | |
500 | type, in_header, matchoff, matchlen); | |
501 | WARN_ON(ret < 0); | |
502 | if (ret == 0) | |
503 | return ret; | |
504 | ||
505 | if (!parse_addr(ct, dptr + *matchoff, &c, addr, limit)) | |
506 | return -1; | |
507 | if (*c == ':') { | |
508 | c++; | |
509 | p = simple_strtoul(c, (char **)&c, 10); | |
510 | if (p < 1024 || p > 65535) | |
511 | return -1; | |
512 | *port = htons(p); | |
513 | } else | |
514 | *port = htons(SIP_PORT); | |
515 | ||
516 | if (dataoff) | |
517 | *dataoff = c - dptr; | |
518 | return 1; | |
519 | } | |
520 | EXPORT_SYMBOL_GPL(ct_sip_parse_header_uri); | |
521 | ||
522 | /* Parse address from header parameter and return address, offset and length */ | |
523 | int ct_sip_parse_address_param(const struct nf_conn *ct, const char *dptr, | |
524 | unsigned int dataoff, unsigned int datalen, | |
525 | const char *name, | |
526 | unsigned int *matchoff, unsigned int *matchlen, | |
527 | union nf_inet_addr *addr) | |
528 | { | |
529 | const char *limit = dptr + datalen; | |
530 | const char *start, *end; | |
531 | ||
532 | limit = ct_sip_header_search(dptr + dataoff, limit, ",", strlen(",")); | |
533 | if (!limit) | |
534 | limit = dptr + datalen; | |
535 | ||
536 | start = ct_sip_header_search(dptr + dataoff, limit, name, strlen(name)); | |
537 | if (!start) | |
538 | return 0; | |
539 | ||
540 | start += strlen(name); | |
541 | if (!parse_addr(ct, start, &end, addr, limit)) | |
542 | return 0; | |
543 | *matchoff = start - dptr; | |
544 | *matchlen = end - start; | |
545 | return 1; | |
546 | } | |
547 | EXPORT_SYMBOL_GPL(ct_sip_parse_address_param); | |
548 | ||
549 | /* Parse numerical header parameter and return value, offset and length */ | |
550 | int ct_sip_parse_numerical_param(const struct nf_conn *ct, const char *dptr, | |
551 | unsigned int dataoff, unsigned int datalen, | |
552 | const char *name, | |
553 | unsigned int *matchoff, unsigned int *matchlen, | |
554 | unsigned int *val) | |
555 | { | |
556 | const char *limit = dptr + datalen; | |
557 | const char *start; | |
558 | char *end; | |
559 | ||
560 | limit = ct_sip_header_search(dptr + dataoff, limit, ",", strlen(",")); | |
561 | if (!limit) | |
562 | limit = dptr + datalen; | |
563 | ||
564 | start = ct_sip_header_search(dptr + dataoff, limit, name, strlen(name)); | |
565 | if (!start) | |
566 | return 0; | |
567 | ||
568 | start += strlen(name); | |
569 | *val = simple_strtoul(start, &end, 0); | |
570 | if (start == end) | |
571 | return 0; | |
572 | if (matchoff && matchlen) { | |
573 | *matchoff = start - dptr; | |
574 | *matchlen = end - start; | |
575 | } | |
576 | return 1; | |
577 | } | |
578 | EXPORT_SYMBOL_GPL(ct_sip_parse_numerical_param); | |
579 | ||
580 | /* SDP header parsing: a SDP session description contains an ordered set of | |
581 | * headers, starting with a section containing general session parameters, | |
582 | * optionally followed by multiple media descriptions. | |
583 | * | |
584 | * SDP headers always start at the beginning of a line. According to RFC 2327: | |
585 | * "The sequence CRLF (0x0d0a) is used to end a record, although parsers should | |
586 | * be tolerant and also accept records terminated with a single newline | |
587 | * character". We handle both cases. | |
588 | */ | |
589 | static const struct sip_header ct_sdp_hdrs[] = { | |
590 | [SDP_HDR_VERSION] = SDP_HDR("v=", NULL, digits_len), | |
591 | [SDP_HDR_OWNER_IP4] = SDP_HDR("o=", "IN IP4 ", epaddr_len), | |
592 | [SDP_HDR_CONNECTION_IP4] = SDP_HDR("c=", "IN IP4 ", epaddr_len), | |
593 | [SDP_HDR_OWNER_IP6] = SDP_HDR("o=", "IN IP6 ", epaddr_len), | |
594 | [SDP_HDR_CONNECTION_IP6] = SDP_HDR("c=", "IN IP6 ", epaddr_len), | |
595 | [SDP_HDR_MEDIA] = SDP_HDR("m=", NULL, media_len), | |
596 | }; | |
597 | ||
598 | /* Linear string search within SDP header values */ | |
599 | static const char *ct_sdp_header_search(const char *dptr, const char *limit, | |
600 | const char *needle, unsigned int len) | |
601 | { | |
602 | for (limit -= len; dptr < limit; dptr++) { | |
603 | if (*dptr == '\r' || *dptr == '\n') | |
604 | break; | |
605 | if (strncmp(dptr, needle, len) == 0) | |
606 | return dptr; | |
607 | } | |
608 | return NULL; | |
609 | } | |
610 | ||
611 | /* Locate a SDP header (optionally a substring within the header value), | |
612 | * optionally stopping at the first occurence of the term header, parse | |
613 | * it and return the offset and length of the data we're interested in. | |
614 | */ | |
615 | int ct_sip_get_sdp_header(const struct nf_conn *ct, const char *dptr, | |
616 | unsigned int dataoff, unsigned int datalen, | |
617 | enum sdp_header_types type, | |
618 | enum sdp_header_types term, | |
619 | unsigned int *matchoff, unsigned int *matchlen) | |
620 | { | |
621 | const struct sip_header *hdr = &ct_sdp_hdrs[type]; | |
622 | const struct sip_header *thdr = &ct_sdp_hdrs[term]; | |
623 | const char *start = dptr, *limit = dptr + datalen; | |
624 | int shift = 0; | |
625 | ||
626 | for (dptr += dataoff; dptr < limit; dptr++) { | |
627 | /* Find beginning of line */ | |
628 | if (*dptr != '\r' && *dptr != '\n') | |
629 | continue; | |
630 | if (++dptr >= limit) | |
631 | break; | |
632 | if (*(dptr - 1) == '\r' && *dptr == '\n') { | |
633 | if (++dptr >= limit) | |
634 | break; | |
635 | } | |
636 | ||
637 | if (term != SDP_HDR_UNSPEC && | |
638 | limit - dptr >= thdr->len && | |
639 | strnicmp(dptr, thdr->name, thdr->len) == 0) | |
640 | break; | |
641 | else if (limit - dptr >= hdr->len && | |
642 | strnicmp(dptr, hdr->name, hdr->len) == 0) | |
643 | dptr += hdr->len; | |
644 | else | |
645 | continue; | |
646 | ||
647 | *matchoff = dptr - start; | |
648 | if (hdr->search) { | |
649 | dptr = ct_sdp_header_search(dptr, limit, hdr->search, | |
650 | hdr->slen); | |
651 | if (!dptr) | |
652 | return -1; | |
653 | dptr += hdr->slen; | |
654 | } | |
655 | ||
656 | *matchlen = hdr->match_len(ct, dptr, limit, &shift); | |
657 | if (!*matchlen) | |
658 | return -1; | |
659 | *matchoff = dptr - start + shift; | |
660 | return 1; | |
661 | } | |
662 | return 0; | |
663 | } | |
664 | EXPORT_SYMBOL_GPL(ct_sip_get_sdp_header); | |
665 | ||
666 | static int ct_sip_parse_sdp_addr(const struct nf_conn *ct, const char *dptr, | |
667 | unsigned int dataoff, unsigned int datalen, | |
668 | enum sdp_header_types type, | |
669 | enum sdp_header_types term, | |
670 | unsigned int *matchoff, unsigned int *matchlen, | |
671 | union nf_inet_addr *addr) | |
672 | { | |
673 | int ret; | |
674 | ||
675 | ret = ct_sip_get_sdp_header(ct, dptr, dataoff, datalen, type, term, | |
676 | matchoff, matchlen); | |
677 | if (ret <= 0) | |
678 | return ret; | |
679 | ||
680 | if (!parse_addr(ct, dptr + *matchoff, NULL, addr, | |
681 | dptr + *matchoff + *matchlen)) | |
682 | return -1; | |
683 | return 1; | |
684 | } | |
685 | ||
686 | static int refresh_signalling_expectation(struct nf_conn *ct, | |
687 | union nf_inet_addr *addr, | |
688 | __be16 port, | |
689 | unsigned int expires) | |
690 | { | |
691 | struct nf_conn_help *help = nfct_help(ct); | |
692 | struct nf_conntrack_expect *exp; | |
693 | struct hlist_node *n, *next; | |
694 | int found = 0; | |
695 | ||
696 | spin_lock_bh(&nf_conntrack_lock); | |
697 | hlist_for_each_entry_safe(exp, n, next, &help->expectations, lnode) { | |
698 | if (exp->class != SIP_EXPECT_SIGNALLING || | |
699 | !nf_inet_addr_cmp(&exp->tuple.dst.u3, addr) || | |
700 | exp->tuple.dst.u.udp.port != port) | |
701 | continue; | |
702 | if (!del_timer(&exp->timeout)) | |
703 | continue; | |
704 | exp->flags &= ~NF_CT_EXPECT_INACTIVE; | |
705 | exp->timeout.expires = jiffies + expires * HZ; | |
706 | add_timer(&exp->timeout); | |
707 | found = 1; | |
708 | break; | |
709 | } | |
710 | spin_unlock_bh(&nf_conntrack_lock); | |
711 | return found; | |
712 | } | |
713 | ||
714 | static void flush_expectations(struct nf_conn *ct, bool media) | |
715 | { | |
716 | struct nf_conn_help *help = nfct_help(ct); | |
717 | struct nf_conntrack_expect *exp; | |
718 | struct hlist_node *n, *next; | |
719 | ||
720 | spin_lock_bh(&nf_conntrack_lock); | |
721 | hlist_for_each_entry_safe(exp, n, next, &help->expectations, lnode) { | |
722 | if ((exp->class != SIP_EXPECT_SIGNALLING) ^ media) | |
723 | continue; | |
724 | if (!del_timer(&exp->timeout)) | |
725 | continue; | |
726 | nf_ct_unlink_expect(exp); | |
727 | nf_ct_expect_put(exp); | |
728 | if (!media) | |
729 | break; | |
730 | } | |
731 | spin_unlock_bh(&nf_conntrack_lock); | |
732 | } | |
733 | ||
734 | static int set_expected_rtp_rtcp(struct sk_buff *skb, unsigned int dataoff, | |
735 | const char **dptr, unsigned int *datalen, | |
736 | union nf_inet_addr *daddr, __be16 port, | |
737 | enum sip_expectation_classes class, | |
738 | unsigned int mediaoff, unsigned int medialen) | |
739 | { | |
740 | struct nf_conntrack_expect *exp, *rtp_exp, *rtcp_exp; | |
741 | enum ip_conntrack_info ctinfo; | |
742 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
743 | struct net *net = nf_ct_net(ct); | |
744 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); | |
745 | union nf_inet_addr *saddr; | |
746 | struct nf_conntrack_tuple tuple; | |
747 | int direct_rtp = 0, skip_expect = 0, ret = NF_DROP; | |
748 | u_int16_t base_port; | |
749 | __be16 rtp_port, rtcp_port; | |
750 | typeof(nf_nat_sdp_port_hook) nf_nat_sdp_port; | |
751 | typeof(nf_nat_sdp_media_hook) nf_nat_sdp_media; | |
752 | ||
753 | saddr = NULL; | |
754 | if (sip_direct_media) { | |
755 | if (!nf_inet_addr_cmp(daddr, &ct->tuplehash[dir].tuple.src.u3)) | |
756 | return NF_ACCEPT; | |
757 | saddr = &ct->tuplehash[!dir].tuple.src.u3; | |
758 | } | |
759 | ||
760 | /* We need to check whether the registration exists before attempting | |
761 | * to register it since we can see the same media description multiple | |
762 | * times on different connections in case multiple endpoints receive | |
763 | * the same call. | |
764 | * | |
765 | * RTP optimization: if we find a matching media channel expectation | |
766 | * and both the expectation and this connection are SNATed, we assume | |
767 | * both sides can reach each other directly and use the final | |
768 | * destination address from the expectation. We still need to keep | |
769 | * the NATed expectations for media that might arrive from the | |
770 | * outside, and additionally need to expect the direct RTP stream | |
771 | * in case it passes through us even without NAT. | |
772 | */ | |
773 | memset(&tuple, 0, sizeof(tuple)); | |
774 | if (saddr) | |
775 | tuple.src.u3 = *saddr; | |
776 | tuple.src.l3num = nf_ct_l3num(ct); | |
777 | tuple.dst.protonum = IPPROTO_UDP; | |
778 | tuple.dst.u3 = *daddr; | |
779 | tuple.dst.u.udp.port = port; | |
780 | ||
781 | rcu_read_lock(); | |
782 | do { | |
783 | exp = __nf_ct_expect_find(net, &tuple); | |
784 | ||
785 | if (!exp || exp->master == ct || | |
786 | nfct_help(exp->master)->helper != nfct_help(ct)->helper || | |
787 | exp->class != class) | |
788 | break; | |
789 | #ifdef CONFIG_NF_NAT_NEEDED | |
790 | if (exp->tuple.src.l3num == AF_INET && !direct_rtp && | |
791 | (exp->saved_ip != exp->tuple.dst.u3.ip || | |
792 | exp->saved_proto.udp.port != exp->tuple.dst.u.udp.port) && | |
793 | ct->status & IPS_NAT_MASK) { | |
794 | daddr->ip = exp->saved_ip; | |
795 | tuple.dst.u3.ip = exp->saved_ip; | |
796 | tuple.dst.u.udp.port = exp->saved_proto.udp.port; | |
797 | direct_rtp = 1; | |
798 | } else | |
799 | #endif | |
800 | skip_expect = 1; | |
801 | } while (!skip_expect); | |
802 | rcu_read_unlock(); | |
803 | ||
804 | base_port = ntohs(tuple.dst.u.udp.port) & ~1; | |
805 | rtp_port = htons(base_port); | |
806 | rtcp_port = htons(base_port + 1); | |
807 | ||
808 | if (direct_rtp) { | |
809 | nf_nat_sdp_port = rcu_dereference(nf_nat_sdp_port_hook); | |
810 | if (nf_nat_sdp_port && | |
811 | !nf_nat_sdp_port(skb, dataoff, dptr, datalen, | |
812 | mediaoff, medialen, ntohs(rtp_port))) | |
813 | goto err1; | |
814 | } | |
815 | ||
816 | if (skip_expect) | |
817 | return NF_ACCEPT; | |
818 | ||
819 | rtp_exp = nf_ct_expect_alloc(ct); | |
820 | if (rtp_exp == NULL) | |
821 | goto err1; | |
822 | nf_ct_expect_init(rtp_exp, class, nf_ct_l3num(ct), saddr, daddr, | |
823 | IPPROTO_UDP, NULL, &rtp_port); | |
824 | ||
825 | rtcp_exp = nf_ct_expect_alloc(ct); | |
826 | if (rtcp_exp == NULL) | |
827 | goto err2; | |
828 | nf_ct_expect_init(rtcp_exp, class, nf_ct_l3num(ct), saddr, daddr, | |
829 | IPPROTO_UDP, NULL, &rtcp_port); | |
830 | ||
831 | nf_nat_sdp_media = rcu_dereference(nf_nat_sdp_media_hook); | |
832 | if (nf_nat_sdp_media && ct->status & IPS_NAT_MASK && !direct_rtp) | |
833 | ret = nf_nat_sdp_media(skb, dataoff, dptr, datalen, | |
834 | rtp_exp, rtcp_exp, | |
835 | mediaoff, medialen, daddr); | |
836 | else { | |
837 | if (nf_ct_expect_related(rtp_exp) == 0) { | |
838 | if (nf_ct_expect_related(rtcp_exp) != 0) | |
839 | nf_ct_unexpect_related(rtp_exp); | |
840 | else | |
841 | ret = NF_ACCEPT; | |
842 | } | |
843 | } | |
844 | nf_ct_expect_put(rtcp_exp); | |
845 | err2: | |
846 | nf_ct_expect_put(rtp_exp); | |
847 | err1: | |
848 | return ret; | |
849 | } | |
850 | ||
851 | static const struct sdp_media_type sdp_media_types[] = { | |
852 | SDP_MEDIA_TYPE("audio ", SIP_EXPECT_AUDIO), | |
853 | SDP_MEDIA_TYPE("video ", SIP_EXPECT_VIDEO), | |
854 | }; | |
855 | ||
856 | static const struct sdp_media_type *sdp_media_type(const char *dptr, | |
857 | unsigned int matchoff, | |
858 | unsigned int matchlen) | |
859 | { | |
860 | const struct sdp_media_type *t; | |
861 | unsigned int i; | |
862 | ||
863 | for (i = 0; i < ARRAY_SIZE(sdp_media_types); i++) { | |
864 | t = &sdp_media_types[i]; | |
865 | if (matchlen < t->len || | |
866 | strncmp(dptr + matchoff, t->name, t->len)) | |
867 | continue; | |
868 | return t; | |
869 | } | |
870 | return NULL; | |
871 | } | |
872 | ||
873 | static int process_sdp(struct sk_buff *skb, unsigned int dataoff, | |
874 | const char **dptr, unsigned int *datalen, | |
875 | unsigned int cseq) | |
876 | { | |
877 | enum ip_conntrack_info ctinfo; | |
878 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
879 | struct nf_conn_help *help = nfct_help(ct); | |
880 | unsigned int matchoff, matchlen; | |
881 | unsigned int mediaoff, medialen; | |
882 | unsigned int sdpoff; | |
883 | unsigned int caddr_len, maddr_len; | |
884 | unsigned int i; | |
885 | union nf_inet_addr caddr, maddr, rtp_addr; | |
886 | unsigned int port; | |
887 | enum sdp_header_types c_hdr; | |
888 | const struct sdp_media_type *t; | |
889 | int ret = NF_ACCEPT; | |
890 | typeof(nf_nat_sdp_addr_hook) nf_nat_sdp_addr; | |
891 | typeof(nf_nat_sdp_session_hook) nf_nat_sdp_session; | |
892 | ||
893 | nf_nat_sdp_addr = rcu_dereference(nf_nat_sdp_addr_hook); | |
894 | c_hdr = nf_ct_l3num(ct) == AF_INET ? SDP_HDR_CONNECTION_IP4 : | |
895 | SDP_HDR_CONNECTION_IP6; | |
896 | ||
897 | /* Find beginning of session description */ | |
898 | if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen, | |
899 | SDP_HDR_VERSION, SDP_HDR_UNSPEC, | |
900 | &matchoff, &matchlen) <= 0) | |
901 | return NF_ACCEPT; | |
902 | sdpoff = matchoff; | |
903 | ||
904 | /* The connection information is contained in the session description | |
905 | * and/or once per media description. The first media description marks | |
906 | * the end of the session description. */ | |
907 | caddr_len = 0; | |
908 | if (ct_sip_parse_sdp_addr(ct, *dptr, sdpoff, *datalen, | |
909 | c_hdr, SDP_HDR_MEDIA, | |
910 | &matchoff, &matchlen, &caddr) > 0) | |
911 | caddr_len = matchlen; | |
912 | ||
913 | mediaoff = sdpoff; | |
914 | for (i = 0; i < ARRAY_SIZE(sdp_media_types); ) { | |
915 | if (ct_sip_get_sdp_header(ct, *dptr, mediaoff, *datalen, | |
916 | SDP_HDR_MEDIA, SDP_HDR_UNSPEC, | |
917 | &mediaoff, &medialen) <= 0) | |
918 | break; | |
919 | ||
920 | /* Get media type and port number. A media port value of zero | |
921 | * indicates an inactive stream. */ | |
922 | t = sdp_media_type(*dptr, mediaoff, medialen); | |
923 | if (!t) { | |
924 | mediaoff += medialen; | |
925 | continue; | |
926 | } | |
927 | mediaoff += t->len; | |
928 | medialen -= t->len; | |
929 | ||
930 | port = simple_strtoul(*dptr + mediaoff, NULL, 10); | |
931 | if (port == 0) | |
932 | continue; | |
933 | if (port < 1024 || port > 65535) | |
934 | return NF_DROP; | |
935 | ||
936 | /* The media description overrides the session description. */ | |
937 | maddr_len = 0; | |
938 | if (ct_sip_parse_sdp_addr(ct, *dptr, mediaoff, *datalen, | |
939 | c_hdr, SDP_HDR_MEDIA, | |
940 | &matchoff, &matchlen, &maddr) > 0) { | |
941 | maddr_len = matchlen; | |
942 | memcpy(&rtp_addr, &maddr, sizeof(rtp_addr)); | |
943 | } else if (caddr_len) | |
944 | memcpy(&rtp_addr, &caddr, sizeof(rtp_addr)); | |
945 | else | |
946 | return NF_DROP; | |
947 | ||
948 | ret = set_expected_rtp_rtcp(skb, dataoff, dptr, datalen, | |
949 | &rtp_addr, htons(port), t->class, | |
950 | mediaoff, medialen); | |
951 | if (ret != NF_ACCEPT) | |
952 | return ret; | |
953 | ||
954 | /* Update media connection address if present */ | |
955 | if (maddr_len && nf_nat_sdp_addr && ct->status & IPS_NAT_MASK) { | |
956 | ret = nf_nat_sdp_addr(skb, dataoff, dptr, datalen, | |
957 | mediaoff, c_hdr, SDP_HDR_MEDIA, | |
958 | &rtp_addr); | |
959 | if (ret != NF_ACCEPT) | |
960 | return ret; | |
961 | } | |
962 | i++; | |
963 | } | |
964 | ||
965 | /* Update session connection and owner addresses */ | |
966 | nf_nat_sdp_session = rcu_dereference(nf_nat_sdp_session_hook); | |
967 | if (nf_nat_sdp_session && ct->status & IPS_NAT_MASK) | |
968 | ret = nf_nat_sdp_session(skb, dataoff, dptr, datalen, sdpoff, | |
969 | &rtp_addr); | |
970 | ||
971 | if (ret == NF_ACCEPT && i > 0) | |
972 | help->help.ct_sip_info.invite_cseq = cseq; | |
973 | ||
974 | return ret; | |
975 | } | |
976 | static int process_invite_response(struct sk_buff *skb, unsigned int dataoff, | |
977 | const char **dptr, unsigned int *datalen, | |
978 | unsigned int cseq, unsigned int code) | |
979 | { | |
980 | enum ip_conntrack_info ctinfo; | |
981 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
982 | struct nf_conn_help *help = nfct_help(ct); | |
983 | ||
984 | if ((code >= 100 && code <= 199) || | |
985 | (code >= 200 && code <= 299)) | |
986 | return process_sdp(skb, dataoff, dptr, datalen, cseq); | |
987 | else if (help->help.ct_sip_info.invite_cseq == cseq) | |
988 | flush_expectations(ct, true); | |
989 | return NF_ACCEPT; | |
990 | } | |
991 | ||
992 | static int process_update_response(struct sk_buff *skb, unsigned int dataoff, | |
993 | const char **dptr, unsigned int *datalen, | |
994 | unsigned int cseq, unsigned int code) | |
995 | { | |
996 | enum ip_conntrack_info ctinfo; | |
997 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
998 | struct nf_conn_help *help = nfct_help(ct); | |
999 | ||
1000 | if ((code >= 100 && code <= 199) || | |
1001 | (code >= 200 && code <= 299)) | |
1002 | return process_sdp(skb, dataoff, dptr, datalen, cseq); | |
1003 | else if (help->help.ct_sip_info.invite_cseq == cseq) | |
1004 | flush_expectations(ct, true); | |
1005 | return NF_ACCEPT; | |
1006 | } | |
1007 | ||
1008 | static int process_prack_response(struct sk_buff *skb, unsigned int dataoff, | |
1009 | const char **dptr, unsigned int *datalen, | |
1010 | unsigned int cseq, unsigned int code) | |
1011 | { | |
1012 | enum ip_conntrack_info ctinfo; | |
1013 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
1014 | struct nf_conn_help *help = nfct_help(ct); | |
1015 | ||
1016 | if ((code >= 100 && code <= 199) || | |
1017 | (code >= 200 && code <= 299)) | |
1018 | return process_sdp(skb, dataoff, dptr, datalen, cseq); | |
1019 | else if (help->help.ct_sip_info.invite_cseq == cseq) | |
1020 | flush_expectations(ct, true); | |
1021 | return NF_ACCEPT; | |
1022 | } | |
1023 | ||
1024 | static int process_bye_request(struct sk_buff *skb, unsigned int dataoff, | |
1025 | const char **dptr, unsigned int *datalen, | |
1026 | unsigned int cseq) | |
1027 | { | |
1028 | enum ip_conntrack_info ctinfo; | |
1029 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
1030 | ||
1031 | flush_expectations(ct, true); | |
1032 | return NF_ACCEPT; | |
1033 | } | |
1034 | ||
1035 | /* Parse a REGISTER request and create a permanent expectation for incoming | |
1036 | * signalling connections. The expectation is marked inactive and is activated | |
1037 | * when receiving a response indicating success from the registrar. | |
1038 | */ | |
1039 | static int process_register_request(struct sk_buff *skb, unsigned int dataoff, | |
1040 | const char **dptr, unsigned int *datalen, | |
1041 | unsigned int cseq) | |
1042 | { | |
1043 | enum ip_conntrack_info ctinfo; | |
1044 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
1045 | struct nf_conn_help *help = nfct_help(ct); | |
1046 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); | |
1047 | unsigned int matchoff, matchlen; | |
1048 | struct nf_conntrack_expect *exp; | |
1049 | union nf_inet_addr *saddr, daddr; | |
1050 | __be16 port; | |
1051 | unsigned int expires = 0; | |
1052 | int ret; | |
1053 | typeof(nf_nat_sip_expect_hook) nf_nat_sip_expect; | |
1054 | ||
1055 | /* Expected connections can not register again. */ | |
1056 | if (ct->status & IPS_EXPECTED) | |
1057 | return NF_ACCEPT; | |
1058 | ||
1059 | /* We must check the expiration time: a value of zero signals the | |
1060 | * registrar to release the binding. We'll remove our expectation | |
1061 | * when receiving the new bindings in the response, but we don't | |
1062 | * want to create new ones. | |
1063 | * | |
1064 | * The expiration time may be contained in Expires: header, the | |
1065 | * Contact: header parameters or the URI parameters. | |
1066 | */ | |
1067 | if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_EXPIRES, | |
1068 | &matchoff, &matchlen) > 0) | |
1069 | expires = simple_strtoul(*dptr + matchoff, NULL, 10); | |
1070 | ||
1071 | ret = ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen, | |
1072 | SIP_HDR_CONTACT, NULL, | |
1073 | &matchoff, &matchlen, &daddr, &port); | |
1074 | if (ret < 0) | |
1075 | return NF_DROP; | |
1076 | else if (ret == 0) | |
1077 | return NF_ACCEPT; | |
1078 | ||
1079 | /* We don't support third-party registrations */ | |
1080 | if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3, &daddr)) | |
1081 | return NF_ACCEPT; | |
1082 | ||
1083 | if (ct_sip_parse_numerical_param(ct, *dptr, | |
1084 | matchoff + matchlen, *datalen, | |
1085 | "expires=", NULL, NULL, &expires) < 0) | |
1086 | return NF_DROP; | |
1087 | ||
1088 | if (expires == 0) { | |
1089 | ret = NF_ACCEPT; | |
1090 | goto store_cseq; | |
1091 | } | |
1092 | ||
1093 | exp = nf_ct_expect_alloc(ct); | |
1094 | if (!exp) | |
1095 | return NF_DROP; | |
1096 | ||
1097 | saddr = NULL; | |
1098 | if (sip_direct_signalling) | |
1099 | saddr = &ct->tuplehash[!dir].tuple.src.u3; | |
1100 | ||
1101 | nf_ct_expect_init(exp, SIP_EXPECT_SIGNALLING, nf_ct_l3num(ct), | |
1102 | saddr, &daddr, IPPROTO_UDP, NULL, &port); | |
1103 | exp->timeout.expires = sip_timeout * HZ; | |
1104 | exp->helper = nfct_help(ct)->helper; | |
1105 | exp->flags = NF_CT_EXPECT_PERMANENT | NF_CT_EXPECT_INACTIVE; | |
1106 | ||
1107 | nf_nat_sip_expect = rcu_dereference(nf_nat_sip_expect_hook); | |
1108 | if (nf_nat_sip_expect && ct->status & IPS_NAT_MASK) | |
1109 | ret = nf_nat_sip_expect(skb, dataoff, dptr, datalen, exp, | |
1110 | matchoff, matchlen); | |
1111 | else { | |
1112 | if (nf_ct_expect_related(exp) != 0) | |
1113 | ret = NF_DROP; | |
1114 | else | |
1115 | ret = NF_ACCEPT; | |
1116 | } | |
1117 | nf_ct_expect_put(exp); | |
1118 | ||
1119 | store_cseq: | |
1120 | if (ret == NF_ACCEPT) | |
1121 | help->help.ct_sip_info.register_cseq = cseq; | |
1122 | return ret; | |
1123 | } | |
1124 | ||
1125 | static int process_register_response(struct sk_buff *skb, unsigned int dataoff, | |
1126 | const char **dptr, unsigned int *datalen, | |
1127 | unsigned int cseq, unsigned int code) | |
1128 | { | |
1129 | enum ip_conntrack_info ctinfo; | |
1130 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
1131 | struct nf_conn_help *help = nfct_help(ct); | |
1132 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); | |
1133 | union nf_inet_addr addr; | |
1134 | __be16 port; | |
1135 | unsigned int matchoff, matchlen, coff = 0; | |
1136 | unsigned int expires = 0; | |
1137 | int in_contact = 0, ret; | |
1138 | ||
1139 | /* According to RFC 3261, "UAs MUST NOT send a new registration until | |
1140 | * they have received a final response from the registrar for the | |
1141 | * previous one or the previous REGISTER request has timed out". | |
1142 | * | |
1143 | * However, some servers fail to detect retransmissions and send late | |
1144 | * responses, so we store the sequence number of the last valid | |
1145 | * request and compare it here. | |
1146 | */ | |
1147 | if (help->help.ct_sip_info.register_cseq != cseq) | |
1148 | return NF_ACCEPT; | |
1149 | ||
1150 | if (code >= 100 && code <= 199) | |
1151 | return NF_ACCEPT; | |
1152 | if (code < 200 || code > 299) | |
1153 | goto flush; | |
1154 | ||
1155 | if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_EXPIRES, | |
1156 | &matchoff, &matchlen) > 0) | |
1157 | expires = simple_strtoul(*dptr + matchoff, NULL, 10); | |
1158 | ||
1159 | while (1) { | |
1160 | unsigned int c_expires = expires; | |
1161 | ||
1162 | ret = ct_sip_parse_header_uri(ct, *dptr, &coff, *datalen, | |
1163 | SIP_HDR_CONTACT, &in_contact, | |
1164 | &matchoff, &matchlen, | |
1165 | &addr, &port); | |
1166 | if (ret < 0) | |
1167 | return NF_DROP; | |
1168 | else if (ret == 0) | |
1169 | break; | |
1170 | ||
1171 | /* We don't support third-party registrations */ | |
1172 | if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3, &addr)) | |
1173 | continue; | |
1174 | ||
1175 | ret = ct_sip_parse_numerical_param(ct, *dptr, | |
1176 | matchoff + matchlen, | |
1177 | *datalen, "expires=", | |
1178 | NULL, NULL, &c_expires); | |
1179 | if (ret < 0) | |
1180 | return NF_DROP; | |
1181 | if (c_expires == 0) | |
1182 | break; | |
1183 | if (refresh_signalling_expectation(ct, &addr, port, c_expires)) | |
1184 | return NF_ACCEPT; | |
1185 | } | |
1186 | ||
1187 | flush: | |
1188 | flush_expectations(ct, false); | |
1189 | return NF_ACCEPT; | |
1190 | } | |
1191 | ||
1192 | static const struct sip_handler sip_handlers[] = { | |
1193 | SIP_HANDLER("INVITE", process_sdp, process_invite_response), | |
1194 | SIP_HANDLER("UPDATE", process_sdp, process_update_response), | |
1195 | SIP_HANDLER("ACK", process_sdp, NULL), | |
1196 | SIP_HANDLER("PRACK", process_sdp, process_prack_response), | |
1197 | SIP_HANDLER("BYE", process_bye_request, NULL), | |
1198 | SIP_HANDLER("REGISTER", process_register_request, process_register_response), | |
1199 | }; | |
1200 | ||
1201 | static int process_sip_response(struct sk_buff *skb, unsigned int dataoff, | |
1202 | const char **dptr, unsigned int *datalen) | |
1203 | { | |
1204 | enum ip_conntrack_info ctinfo; | |
1205 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
1206 | unsigned int matchoff, matchlen, matchend; | |
1207 | unsigned int code, cseq, i; | |
1208 | ||
1209 | if (*datalen < strlen("SIP/2.0 200")) | |
1210 | return NF_ACCEPT; | |
1211 | code = simple_strtoul(*dptr + strlen("SIP/2.0 "), NULL, 10); | |
1212 | if (!code) | |
1213 | return NF_DROP; | |
1214 | ||
1215 | if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CSEQ, | |
1216 | &matchoff, &matchlen) <= 0) | |
1217 | return NF_DROP; | |
1218 | cseq = simple_strtoul(*dptr + matchoff, NULL, 10); | |
1219 | if (!cseq) | |
1220 | return NF_DROP; | |
1221 | matchend = matchoff + matchlen + 1; | |
1222 | ||
1223 | for (i = 0; i < ARRAY_SIZE(sip_handlers); i++) { | |
1224 | const struct sip_handler *handler; | |
1225 | ||
1226 | handler = &sip_handlers[i]; | |
1227 | if (handler->response == NULL) | |
1228 | continue; | |
1229 | if (*datalen < matchend + handler->len || | |
1230 | strnicmp(*dptr + matchend, handler->method, handler->len)) | |
1231 | continue; | |
1232 | return handler->response(skb, dataoff, dptr, datalen, | |
1233 | cseq, code); | |
1234 | } | |
1235 | return NF_ACCEPT; | |
1236 | } | |
1237 | ||
1238 | static int process_sip_request(struct sk_buff *skb, unsigned int dataoff, | |
1239 | const char **dptr, unsigned int *datalen) | |
1240 | { | |
1241 | enum ip_conntrack_info ctinfo; | |
1242 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
1243 | unsigned int matchoff, matchlen; | |
1244 | unsigned int cseq, i; | |
1245 | ||
1246 | for (i = 0; i < ARRAY_SIZE(sip_handlers); i++) { | |
1247 | const struct sip_handler *handler; | |
1248 | ||
1249 | handler = &sip_handlers[i]; | |
1250 | if (handler->request == NULL) | |
1251 | continue; | |
1252 | if (*datalen < handler->len || | |
1253 | strnicmp(*dptr, handler->method, handler->len)) | |
1254 | continue; | |
1255 | ||
1256 | if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CSEQ, | |
1257 | &matchoff, &matchlen) <= 0) | |
1258 | return NF_DROP; | |
1259 | cseq = simple_strtoul(*dptr + matchoff, NULL, 10); | |
1260 | if (!cseq) | |
1261 | return NF_DROP; | |
1262 | ||
1263 | return handler->request(skb, dataoff, dptr, datalen, cseq); | |
1264 | } | |
1265 | return NF_ACCEPT; | |
1266 | } | |
1267 | ||
1268 | static int sip_help(struct sk_buff *skb, | |
1269 | unsigned int protoff, | |
1270 | struct nf_conn *ct, | |
1271 | enum ip_conntrack_info ctinfo) | |
1272 | { | |
1273 | unsigned int dataoff, datalen; | |
1274 | const char *dptr; | |
1275 | int ret; | |
1276 | typeof(nf_nat_sip_hook) nf_nat_sip; | |
1277 | ||
1278 | /* No Data ? */ | |
1279 | dataoff = protoff + sizeof(struct udphdr); | |
1280 | if (dataoff >= skb->len) | |
1281 | return NF_ACCEPT; | |
1282 | ||
1283 | nf_ct_refresh(ct, skb, sip_timeout * HZ); | |
1284 | ||
1285 | if (!skb_is_nonlinear(skb)) | |
1286 | dptr = skb->data + dataoff; | |
1287 | else { | |
1288 | pr_debug("Copy of skbuff not supported yet.\n"); | |
1289 | return NF_ACCEPT; | |
1290 | } | |
1291 | ||
1292 | datalen = skb->len - dataoff; | |
1293 | if (datalen < strlen("SIP/2.0 200")) | |
1294 | return NF_ACCEPT; | |
1295 | ||
1296 | if (strnicmp(dptr, "SIP/2.0 ", strlen("SIP/2.0 ")) != 0) | |
1297 | ret = process_sip_request(skb, dataoff, &dptr, &datalen); | |
1298 | else | |
1299 | ret = process_sip_response(skb, dataoff, &dptr, &datalen); | |
1300 | ||
1301 | if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) { | |
1302 | nf_nat_sip = rcu_dereference(nf_nat_sip_hook); | |
1303 | if (nf_nat_sip && !nf_nat_sip(skb, dataoff, &dptr, &datalen)) | |
1304 | ret = NF_DROP; | |
1305 | } | |
1306 | ||
1307 | return ret; | |
1308 | } | |
1309 | ||
1310 | static struct nf_conntrack_helper sip[MAX_PORTS][2] __read_mostly; | |
1311 | static char sip_names[MAX_PORTS][2][sizeof("sip-65535")] __read_mostly; | |
1312 | ||
1313 | static const struct nf_conntrack_expect_policy sip_exp_policy[SIP_EXPECT_MAX + 1] = { | |
1314 | [SIP_EXPECT_SIGNALLING] = { | |
1315 | .name = "signalling", | |
1316 | .max_expected = 1, | |
1317 | .timeout = 3 * 60, | |
1318 | }, | |
1319 | [SIP_EXPECT_AUDIO] = { | |
1320 | .name = "audio", | |
1321 | .max_expected = 2 * IP_CT_DIR_MAX, | |
1322 | .timeout = 3 * 60, | |
1323 | }, | |
1324 | [SIP_EXPECT_VIDEO] = { | |
1325 | .name = "video", | |
1326 | .max_expected = 2 * IP_CT_DIR_MAX, | |
1327 | .timeout = 3 * 60, | |
1328 | }, | |
1329 | }; | |
1330 | ||
1331 | static void nf_conntrack_sip_fini(void) | |
1332 | { | |
1333 | int i, j; | |
1334 | ||
1335 | for (i = 0; i < ports_c; i++) { | |
1336 | for (j = 0; j < 2; j++) { | |
1337 | if (sip[i][j].me == NULL) | |
1338 | continue; | |
1339 | nf_conntrack_helper_unregister(&sip[i][j]); | |
1340 | } | |
1341 | } | |
1342 | } | |
1343 | ||
1344 | static int __init nf_conntrack_sip_init(void) | |
1345 | { | |
1346 | int i, j, ret; | |
1347 | char *tmpname; | |
1348 | ||
1349 | if (ports_c == 0) | |
1350 | ports[ports_c++] = SIP_PORT; | |
1351 | ||
1352 | for (i = 0; i < ports_c; i++) { | |
1353 | memset(&sip[i], 0, sizeof(sip[i])); | |
1354 | ||
1355 | sip[i][0].tuple.src.l3num = AF_INET; | |
1356 | sip[i][1].tuple.src.l3num = AF_INET6; | |
1357 | for (j = 0; j < 2; j++) { | |
1358 | sip[i][j].tuple.dst.protonum = IPPROTO_UDP; | |
1359 | sip[i][j].tuple.src.u.udp.port = htons(ports[i]); | |
1360 | sip[i][j].expect_policy = sip_exp_policy; | |
1361 | sip[i][j].expect_class_max = SIP_EXPECT_MAX; | |
1362 | sip[i][j].me = THIS_MODULE; | |
1363 | sip[i][j].help = sip_help; | |
1364 | ||
1365 | tmpname = &sip_names[i][j][0]; | |
1366 | if (ports[i] == SIP_PORT) | |
1367 | sprintf(tmpname, "sip"); | |
1368 | else | |
1369 | sprintf(tmpname, "sip-%u", i); | |
1370 | sip[i][j].name = tmpname; | |
1371 | ||
1372 | pr_debug("port #%u: %u\n", i, ports[i]); | |
1373 | ||
1374 | ret = nf_conntrack_helper_register(&sip[i][j]); | |
1375 | if (ret) { | |
1376 | printk("nf_ct_sip: failed to register helper " | |
1377 | "for pf: %u port: %u\n", | |
1378 | sip[i][j].tuple.src.l3num, ports[i]); | |
1379 | nf_conntrack_sip_fini(); | |
1380 | return ret; | |
1381 | } | |
1382 | } | |
1383 | } | |
1384 | return 0; | |
1385 | } | |
1386 | ||
1387 | module_init(nf_conntrack_sip_init); | |
1388 | module_exit(nf_conntrack_sip_fini); |