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9fafcd7b PM |
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 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License version 2 as | |
8 | * published by the Free Software Foundation. | |
9 | */ | |
10 | ||
11 | #include <linux/module.h> | |
12 | #include <linux/ctype.h> | |
13 | #include <linux/skbuff.h> | |
14 | #include <linux/inet.h> | |
15 | #include <linux/in.h> | |
16 | #include <linux/udp.h> | |
1863f096 | 17 | #include <linux/netfilter.h> |
9fafcd7b PM |
18 | |
19 | #include <net/netfilter/nf_conntrack.h> | |
9467ee38 | 20 | #include <net/netfilter/nf_conntrack_core.h> |
9fafcd7b PM |
21 | #include <net/netfilter/nf_conntrack_expect.h> |
22 | #include <net/netfilter/nf_conntrack_helper.h> | |
23 | #include <linux/netfilter/nf_conntrack_sip.h> | |
24 | ||
9fafcd7b PM |
25 | MODULE_LICENSE("GPL"); |
26 | MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>"); | |
27 | MODULE_DESCRIPTION("SIP connection tracking helper"); | |
28 | MODULE_ALIAS("ip_conntrack_sip"); | |
29 | ||
30 | #define MAX_PORTS 8 | |
31 | static unsigned short ports[MAX_PORTS]; | |
2f0d2f10 | 32 | static unsigned int ports_c; |
9fafcd7b PM |
33 | module_param_array(ports, ushort, &ports_c, 0400); |
34 | MODULE_PARM_DESC(ports, "port numbers of SIP servers"); | |
35 | ||
36 | static unsigned int sip_timeout __read_mostly = SIP_TIMEOUT; | |
37 | module_param(sip_timeout, uint, 0600); | |
38 | MODULE_PARM_DESC(sip_timeout, "timeout for the master SIP session"); | |
39 | ||
3db05fea | 40 | unsigned int (*nf_nat_sip_hook)(struct sk_buff *skb, |
2a6cfb22 PM |
41 | const char **dptr, |
42 | unsigned int *datalen) __read_mostly; | |
9fafcd7b PM |
43 | EXPORT_SYMBOL_GPL(nf_nat_sip_hook); |
44 | ||
3db05fea | 45 | unsigned int (*nf_nat_sdp_hook)(struct sk_buff *skb, |
2a6cfb22 | 46 | const char **dptr, |
212440a7 PM |
47 | unsigned int *datalen, |
48 | struct nf_conntrack_expect *exp) __read_mostly; | |
9fafcd7b PM |
49 | EXPORT_SYMBOL_GPL(nf_nat_sdp_hook); |
50 | ||
ac367740 PM |
51 | static int string_len(const struct nf_conn *ct, const char *dptr, |
52 | const char *limit, int *shift) | |
53 | { | |
54 | int len = 0; | |
55 | ||
56 | while (dptr < limit && isalpha(*dptr)) { | |
57 | dptr++; | |
58 | len++; | |
59 | } | |
60 | return len; | |
61 | } | |
62 | ||
13f7d63c | 63 | static int digits_len(const struct nf_conn *ct, const char *dptr, |
9fafcd7b PM |
64 | const char *limit, int *shift) |
65 | { | |
66 | int len = 0; | |
b1ec488b | 67 | while (dptr < limit && isdigit(*dptr)) { |
9fafcd7b PM |
68 | dptr++; |
69 | len++; | |
70 | } | |
71 | return len; | |
72 | } | |
73 | ||
13f7d63c JE |
74 | static int parse_addr(const struct nf_conn *ct, const char *cp, |
75 | const char **endp, union nf_inet_addr *addr, | |
76 | const char *limit) | |
9fafcd7b PM |
77 | { |
78 | const char *end; | |
79 | int family = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num; | |
80 | int ret = 0; | |
81 | ||
82 | switch (family) { | |
83 | case AF_INET: | |
84 | ret = in4_pton(cp, limit - cp, (u8 *)&addr->ip, -1, &end); | |
85 | break; | |
86 | case AF_INET6: | |
87 | ret = in6_pton(cp, limit - cp, (u8 *)&addr->ip6, -1, &end); | |
88 | break; | |
89 | default: | |
90 | BUG(); | |
91 | } | |
92 | ||
93 | if (ret == 0 || end == cp) | |
94 | return 0; | |
95 | if (endp) | |
96 | *endp = end; | |
97 | return 1; | |
98 | } | |
99 | ||
100 | /* skip ip address. returns its length. */ | |
13f7d63c | 101 | static int epaddr_len(const struct nf_conn *ct, const char *dptr, |
9fafcd7b PM |
102 | const char *limit, int *shift) |
103 | { | |
643a2c15 | 104 | union nf_inet_addr addr; |
9fafcd7b PM |
105 | const char *aux = dptr; |
106 | ||
107 | if (!parse_addr(ct, dptr, &dptr, &addr, limit)) { | |
0d53778e | 108 | pr_debug("ip: %s parse failed.!\n", dptr); |
9fafcd7b PM |
109 | return 0; |
110 | } | |
111 | ||
112 | /* Port number */ | |
113 | if (*dptr == ':') { | |
114 | dptr++; | |
115 | dptr += digits_len(ct, dptr, limit, shift); | |
116 | } | |
117 | return dptr - aux; | |
118 | } | |
119 | ||
120 | /* get address length, skiping user info. */ | |
13f7d63c | 121 | static int skp_epaddr_len(const struct nf_conn *ct, const char *dptr, |
9fafcd7b PM |
122 | const char *limit, int *shift) |
123 | { | |
aa584eda | 124 | const char *start = dptr; |
9fafcd7b PM |
125 | int s = *shift; |
126 | ||
7da5bfbb LI |
127 | /* Search for @, but stop at the end of the line. |
128 | * We are inside a sip: URI, so we don't need to worry about | |
129 | * continuation lines. */ | |
b1ec488b | 130 | while (dptr < limit && |
7da5bfbb | 131 | *dptr != '@' && *dptr != '\r' && *dptr != '\n') { |
9fafcd7b | 132 | (*shift)++; |
7da5bfbb LI |
133 | dptr++; |
134 | } | |
9fafcd7b | 135 | |
b1ec488b | 136 | if (dptr < limit && *dptr == '@') { |
9fafcd7b PM |
137 | dptr++; |
138 | (*shift)++; | |
aa584eda PM |
139 | } else { |
140 | dptr = start; | |
9fafcd7b | 141 | *shift = s; |
aa584eda | 142 | } |
9fafcd7b PM |
143 | |
144 | return epaddr_len(ct, dptr, limit, shift); | |
145 | } | |
146 | ||
ac367740 PM |
147 | /* Parse a SIP request line of the form: |
148 | * | |
149 | * Request-Line = Method SP Request-URI SP SIP-Version CRLF | |
150 | * | |
151 | * and return the offset and length of the address contained in the Request-URI. | |
152 | */ | |
153 | int ct_sip_parse_request(const struct nf_conn *ct, | |
154 | const char *dptr, unsigned int datalen, | |
624f8b7b PM |
155 | unsigned int *matchoff, unsigned int *matchlen, |
156 | union nf_inet_addr *addr, __be16 *port) | |
ac367740 | 157 | { |
624f8b7b | 158 | const char *start = dptr, *limit = dptr + datalen, *end; |
ac367740 | 159 | unsigned int mlen; |
624f8b7b | 160 | unsigned int p; |
ac367740 PM |
161 | int shift = 0; |
162 | ||
163 | /* Skip method and following whitespace */ | |
164 | mlen = string_len(ct, dptr, limit, NULL); | |
165 | if (!mlen) | |
166 | return 0; | |
167 | dptr += mlen; | |
168 | if (++dptr >= limit) | |
169 | return 0; | |
170 | ||
171 | /* Find SIP URI */ | |
172 | limit -= strlen("sip:"); | |
173 | for (; dptr < limit; dptr++) { | |
174 | if (*dptr == '\r' || *dptr == '\n') | |
175 | return -1; | |
176 | if (strnicmp(dptr, "sip:", strlen("sip:")) == 0) | |
177 | break; | |
178 | } | |
624f8b7b | 179 | if (!skp_epaddr_len(ct, dptr, limit, &shift)) |
ac367740 | 180 | return 0; |
624f8b7b PM |
181 | dptr += shift; |
182 | ||
183 | if (!parse_addr(ct, dptr, &end, addr, limit)) | |
184 | return -1; | |
185 | if (end < limit && *end == ':') { | |
186 | end++; | |
187 | p = simple_strtoul(end, (char **)&end, 10); | |
188 | if (p < 1024 || p > 65535) | |
189 | return -1; | |
190 | *port = htons(p); | |
191 | } else | |
192 | *port = htons(SIP_PORT); | |
193 | ||
194 | if (end == dptr) | |
195 | return 0; | |
196 | *matchoff = dptr - start; | |
197 | *matchlen = end - dptr; | |
ac367740 PM |
198 | return 1; |
199 | } | |
200 | EXPORT_SYMBOL_GPL(ct_sip_parse_request); | |
201 | ||
ea45f12a PM |
202 | /* SIP header parsing: SIP headers are located at the beginning of a line, but |
203 | * may span several lines, in which case the continuation lines begin with a | |
204 | * whitespace character. RFC 2543 allows lines to be terminated with CR, LF or | |
205 | * CRLF, RFC 3261 allows only CRLF, we support both. | |
206 | * | |
207 | * Headers are followed by (optionally) whitespace, a colon, again (optionally) | |
208 | * whitespace and the values. Whitespace in this context means any amount of | |
209 | * tabs, spaces and continuation lines, which are treated as a single whitespace | |
210 | * character. | |
05e3ced2 PM |
211 | * |
212 | * Some headers may appear multiple times. A comma seperated list of values is | |
213 | * equivalent to multiple headers. | |
ea45f12a PM |
214 | */ |
215 | static const struct sip_header ct_sip_hdrs[] = { | |
30f33e6d | 216 | [SIP_HDR_CSEQ] = SIP_HDR("CSeq", NULL, NULL, digits_len), |
ea45f12a PM |
217 | [SIP_HDR_FROM] = SIP_HDR("From", "f", "sip:", skp_epaddr_len), |
218 | [SIP_HDR_TO] = SIP_HDR("To", "t", "sip:", skp_epaddr_len), | |
219 | [SIP_HDR_CONTACT] = SIP_HDR("Contact", "m", "sip:", skp_epaddr_len), | |
220 | [SIP_HDR_VIA] = SIP_HDR("Via", "v", "UDP ", epaddr_len), | |
221 | [SIP_HDR_CONTENT_LENGTH] = SIP_HDR("Content-Length", "l", NULL, digits_len), | |
222 | }; | |
223 | ||
224 | static const char *sip_follow_continuation(const char *dptr, const char *limit) | |
9fafcd7b | 225 | { |
ea45f12a PM |
226 | /* Walk past newline */ |
227 | if (++dptr >= limit) | |
228 | return NULL; | |
229 | ||
230 | /* Skip '\n' in CR LF */ | |
231 | if (*(dptr - 1) == '\r' && *dptr == '\n') { | |
232 | if (++dptr >= limit) | |
233 | return NULL; | |
234 | } | |
9fafcd7b | 235 | |
ea45f12a PM |
236 | /* Continuation line? */ |
237 | if (*dptr != ' ' && *dptr != '\t') | |
238 | return NULL; | |
9fafcd7b | 239 | |
ea45f12a PM |
240 | /* skip leading whitespace */ |
241 | for (; dptr < limit; dptr++) { | |
242 | if (*dptr != ' ' && *dptr != '\t') | |
243 | break; | |
244 | } | |
245 | return dptr; | |
246 | } | |
247 | ||
248 | static const char *sip_skip_whitespace(const char *dptr, const char *limit) | |
249 | { | |
250 | for (; dptr < limit; dptr++) { | |
251 | if (*dptr == ' ') | |
252 | continue; | |
253 | if (*dptr != '\r' && *dptr != '\n') | |
254 | break; | |
255 | dptr = sip_follow_continuation(dptr, limit); | |
256 | if (dptr == NULL) | |
257 | return NULL; | |
258 | } | |
259 | return dptr; | |
260 | } | |
261 | ||
262 | /* Search within a SIP header value, dealing with continuation lines */ | |
263 | static const char *ct_sip_header_search(const char *dptr, const char *limit, | |
264 | const char *needle, unsigned int len) | |
265 | { | |
266 | for (limit -= len; dptr < limit; dptr++) { | |
267 | if (*dptr == '\r' || *dptr == '\n') { | |
268 | dptr = sip_follow_continuation(dptr, limit); | |
269 | if (dptr == NULL) | |
270 | break; | |
9fafcd7b PM |
271 | continue; |
272 | } | |
ea45f12a PM |
273 | |
274 | if (strnicmp(dptr, needle, len) == 0) | |
275 | return dptr; | |
276 | } | |
277 | return NULL; | |
278 | } | |
279 | ||
280 | int ct_sip_get_header(const struct nf_conn *ct, const char *dptr, | |
281 | unsigned int dataoff, unsigned int datalen, | |
282 | enum sip_header_types type, | |
283 | unsigned int *matchoff, unsigned int *matchlen) | |
284 | { | |
285 | const struct sip_header *hdr = &ct_sip_hdrs[type]; | |
286 | const char *start = dptr, *limit = dptr + datalen; | |
287 | int shift = 0; | |
288 | ||
289 | for (dptr += dataoff; dptr < limit; dptr++) { | |
290 | /* Find beginning of line */ | |
291 | if (*dptr != '\r' && *dptr != '\n') | |
292 | continue; | |
293 | if (++dptr >= limit) | |
294 | break; | |
295 | if (*(dptr - 1) == '\r' && *dptr == '\n') { | |
296 | if (++dptr >= limit) | |
297 | break; | |
9fafcd7b | 298 | } |
9fafcd7b | 299 | |
ea45f12a PM |
300 | /* Skip continuation lines */ |
301 | if (*dptr == ' ' || *dptr == '\t') | |
302 | continue; | |
9fafcd7b | 303 | |
ea45f12a PM |
304 | /* Find header. Compact headers must be followed by a |
305 | * non-alphabetic character to avoid mismatches. */ | |
306 | if (limit - dptr >= hdr->len && | |
307 | strnicmp(dptr, hdr->name, hdr->len) == 0) | |
308 | dptr += hdr->len; | |
309 | else if (hdr->cname && limit - dptr >= hdr->clen + 1 && | |
310 | strnicmp(dptr, hdr->cname, hdr->clen) == 0 && | |
311 | !isalpha(*(dptr + hdr->clen + 1))) | |
312 | dptr += hdr->clen; | |
313 | else | |
314 | continue; | |
9fafcd7b | 315 | |
ea45f12a PM |
316 | /* Find and skip colon */ |
317 | dptr = sip_skip_whitespace(dptr, limit); | |
318 | if (dptr == NULL) | |
319 | break; | |
320 | if (*dptr != ':' || ++dptr >= limit) | |
321 | break; | |
322 | ||
323 | /* Skip whitespace after colon */ | |
324 | dptr = sip_skip_whitespace(dptr, limit); | |
325 | if (dptr == NULL) | |
326 | break; | |
327 | ||
328 | *matchoff = dptr - start; | |
329 | if (hdr->search) { | |
330 | dptr = ct_sip_header_search(dptr, limit, hdr->search, | |
331 | hdr->slen); | |
332 | if (!dptr) | |
333 | return -1; | |
334 | dptr += hdr->slen; | |
335 | } | |
336 | ||
337 | *matchlen = hdr->match_len(ct, dptr, limit, &shift); | |
338 | if (!*matchlen) | |
339 | return -1; | |
340 | *matchoff = dptr - start + shift; | |
9fafcd7b PM |
341 | return 1; |
342 | } | |
9fafcd7b PM |
343 | return 0; |
344 | } | |
ea45f12a | 345 | EXPORT_SYMBOL_GPL(ct_sip_get_header); |
9fafcd7b | 346 | |
05e3ced2 PM |
347 | /* Get next header field in a list of comma seperated values */ |
348 | static int ct_sip_next_header(const struct nf_conn *ct, const char *dptr, | |
349 | unsigned int dataoff, unsigned int datalen, | |
350 | enum sip_header_types type, | |
351 | unsigned int *matchoff, unsigned int *matchlen) | |
352 | { | |
353 | const struct sip_header *hdr = &ct_sip_hdrs[type]; | |
354 | const char *start = dptr, *limit = dptr + datalen; | |
355 | int shift = 0; | |
356 | ||
357 | dptr += dataoff; | |
358 | ||
359 | dptr = ct_sip_header_search(dptr, limit, ",", strlen(",")); | |
360 | if (!dptr) | |
361 | return 0; | |
362 | ||
363 | dptr = ct_sip_header_search(dptr, limit, hdr->search, hdr->slen); | |
364 | if (!dptr) | |
365 | return 0; | |
366 | dptr += hdr->slen; | |
367 | ||
368 | *matchoff = dptr - start; | |
369 | *matchlen = hdr->match_len(ct, dptr, limit, &shift); | |
370 | if (!*matchlen) | |
371 | return -1; | |
372 | *matchoff += shift; | |
373 | return 1; | |
374 | } | |
375 | ||
376 | /* Walk through headers until a parsable one is found or no header of the | |
377 | * given type is left. */ | |
378 | static int ct_sip_walk_headers(const struct nf_conn *ct, const char *dptr, | |
379 | unsigned int dataoff, unsigned int datalen, | |
380 | enum sip_header_types type, int *in_header, | |
381 | unsigned int *matchoff, unsigned int *matchlen) | |
382 | { | |
383 | int ret; | |
384 | ||
385 | if (in_header && *in_header) { | |
386 | while (1) { | |
387 | ret = ct_sip_next_header(ct, dptr, dataoff, datalen, | |
388 | type, matchoff, matchlen); | |
389 | if (ret > 0) | |
390 | return ret; | |
391 | if (ret == 0) | |
392 | break; | |
393 | dataoff += *matchoff; | |
394 | } | |
395 | *in_header = 0; | |
396 | } | |
397 | ||
398 | while (1) { | |
399 | ret = ct_sip_get_header(ct, dptr, dataoff, datalen, | |
400 | type, matchoff, matchlen); | |
401 | if (ret > 0) | |
402 | break; | |
403 | if (ret == 0) | |
404 | return ret; | |
405 | dataoff += *matchoff; | |
406 | } | |
407 | ||
408 | if (in_header) | |
409 | *in_header = 1; | |
410 | return 1; | |
411 | } | |
412 | ||
413 | /* Locate a SIP header, parse the URI and return the offset and length of | |
414 | * the address as well as the address and port themselves. A stream of | |
415 | * headers can be parsed by handing in a non-NULL datalen and in_header | |
416 | * pointer. | |
417 | */ | |
418 | int ct_sip_parse_header_uri(const struct nf_conn *ct, const char *dptr, | |
419 | unsigned int *dataoff, unsigned int datalen, | |
420 | enum sip_header_types type, int *in_header, | |
421 | unsigned int *matchoff, unsigned int *matchlen, | |
422 | union nf_inet_addr *addr, __be16 *port) | |
423 | { | |
424 | const char *c, *limit = dptr + datalen; | |
425 | unsigned int p; | |
426 | int ret; | |
427 | ||
428 | ret = ct_sip_walk_headers(ct, dptr, dataoff ? *dataoff : 0, datalen, | |
429 | type, in_header, matchoff, matchlen); | |
430 | WARN_ON(ret < 0); | |
431 | if (ret == 0) | |
432 | return ret; | |
433 | ||
434 | if (!parse_addr(ct, dptr + *matchoff, &c, addr, limit)) | |
435 | return -1; | |
436 | if (*c == ':') { | |
437 | c++; | |
438 | p = simple_strtoul(c, (char **)&c, 10); | |
439 | if (p < 1024 || p > 65535) | |
440 | return -1; | |
441 | *port = htons(p); | |
442 | } else | |
443 | *port = htons(SIP_PORT); | |
444 | ||
445 | if (dataoff) | |
446 | *dataoff = c - dptr; | |
447 | return 1; | |
448 | } | |
449 | EXPORT_SYMBOL_GPL(ct_sip_parse_header_uri); | |
450 | ||
2bbb2116 PM |
451 | /* Parse address from header parameter and return address, offset and length */ |
452 | int ct_sip_parse_address_param(const struct nf_conn *ct, const char *dptr, | |
453 | unsigned int dataoff, unsigned int datalen, | |
454 | const char *name, | |
455 | unsigned int *matchoff, unsigned int *matchlen, | |
456 | union nf_inet_addr *addr) | |
457 | { | |
458 | const char *limit = dptr + datalen; | |
459 | const char *start, *end; | |
460 | ||
461 | limit = ct_sip_header_search(dptr + dataoff, limit, ",", strlen(",")); | |
462 | if (!limit) | |
463 | limit = dptr + datalen; | |
464 | ||
465 | start = ct_sip_header_search(dptr + dataoff, limit, name, strlen(name)); | |
466 | if (!start) | |
467 | return 0; | |
468 | ||
469 | start += strlen(name); | |
470 | if (!parse_addr(ct, start, &end, addr, limit)) | |
471 | return 0; | |
472 | *matchoff = start - dptr; | |
473 | *matchlen = end - start; | |
474 | return 1; | |
475 | } | |
476 | EXPORT_SYMBOL_GPL(ct_sip_parse_address_param); | |
477 | ||
478 | /* Parse numerical header parameter and return value, offset and length */ | |
479 | int ct_sip_parse_numerical_param(const struct nf_conn *ct, const char *dptr, | |
480 | unsigned int dataoff, unsigned int datalen, | |
481 | const char *name, | |
482 | unsigned int *matchoff, unsigned int *matchlen, | |
483 | unsigned int *val) | |
484 | { | |
485 | const char *limit = dptr + datalen; | |
486 | const char *start; | |
487 | char *end; | |
488 | ||
489 | limit = ct_sip_header_search(dptr + dataoff, limit, ",", strlen(",")); | |
490 | if (!limit) | |
491 | limit = dptr + datalen; | |
492 | ||
493 | start = ct_sip_header_search(dptr + dataoff, limit, name, strlen(name)); | |
494 | if (!start) | |
495 | return 0; | |
496 | ||
497 | start += strlen(name); | |
498 | *val = simple_strtoul(start, &end, 0); | |
499 | if (start == end) | |
500 | return 0; | |
501 | if (matchoff && matchlen) { | |
502 | *matchoff = start - dptr; | |
503 | *matchlen = end - start; | |
504 | } | |
505 | return 1; | |
506 | } | |
507 | EXPORT_SYMBOL_GPL(ct_sip_parse_numerical_param); | |
508 | ||
3e9b4600 PM |
509 | /* SDP header parsing: a SDP session description contains an ordered set of |
510 | * headers, starting with a section containing general session parameters, | |
511 | * optionally followed by multiple media descriptions. | |
512 | * | |
513 | * SDP headers always start at the beginning of a line. According to RFC 2327: | |
514 | * "The sequence CRLF (0x0d0a) is used to end a record, although parsers should | |
515 | * be tolerant and also accept records terminated with a single newline | |
516 | * character". We handle both cases. | |
517 | */ | |
518 | static const struct sip_header ct_sdp_hdrs[] = { | |
519 | [SDP_HDR_VERSION] = SDP_HDR("v=", NULL, digits_len), | |
520 | [SDP_HDR_OWNER_IP4] = SDP_HDR("o=", "IN IP4 ", epaddr_len), | |
521 | [SDP_HDR_CONNECTION_IP4] = SDP_HDR("c=", "IN IP4 ", epaddr_len), | |
522 | [SDP_HDR_OWNER_IP6] = SDP_HDR("o=", "IN IP6 ", epaddr_len), | |
523 | [SDP_HDR_CONNECTION_IP6] = SDP_HDR("c=", "IN IP6 ", epaddr_len), | |
524 | [SDP_HDR_MEDIA] = SDP_HDR("m=", "audio ", digits_len), | |
525 | }; | |
526 | ||
527 | /* Linear string search within SDP header values */ | |
528 | static const char *ct_sdp_header_search(const char *dptr, const char *limit, | |
529 | const char *needle, unsigned int len) | |
530 | { | |
531 | for (limit -= len; dptr < limit; dptr++) { | |
532 | if (*dptr == '\r' || *dptr == '\n') | |
533 | break; | |
534 | if (strncmp(dptr, needle, len) == 0) | |
535 | return dptr; | |
536 | } | |
537 | return NULL; | |
538 | } | |
539 | ||
540 | /* Locate a SDP header (optionally a substring within the header value), | |
541 | * optionally stopping at the first occurence of the term header, parse | |
542 | * it and return the offset and length of the data we're interested in. | |
543 | */ | |
544 | int ct_sip_get_sdp_header(const struct nf_conn *ct, const char *dptr, | |
545 | unsigned int dataoff, unsigned int datalen, | |
546 | enum sdp_header_types type, | |
547 | enum sdp_header_types term, | |
548 | unsigned int *matchoff, unsigned int *matchlen) | |
549 | { | |
550 | const struct sip_header *hdr = &ct_sdp_hdrs[type]; | |
551 | const struct sip_header *thdr = &ct_sdp_hdrs[term]; | |
552 | const char *start = dptr, *limit = dptr + datalen; | |
553 | int shift = 0; | |
554 | ||
555 | for (dptr += dataoff; dptr < limit; dptr++) { | |
556 | /* Find beginning of line */ | |
557 | if (*dptr != '\r' && *dptr != '\n') | |
558 | continue; | |
559 | if (++dptr >= limit) | |
560 | break; | |
561 | if (*(dptr - 1) == '\r' && *dptr == '\n') { | |
562 | if (++dptr >= limit) | |
563 | break; | |
564 | } | |
565 | ||
566 | if (term != SDP_HDR_UNSPEC && | |
567 | limit - dptr >= thdr->len && | |
568 | strnicmp(dptr, thdr->name, thdr->len) == 0) | |
569 | break; | |
570 | else if (limit - dptr >= hdr->len && | |
571 | strnicmp(dptr, hdr->name, hdr->len) == 0) | |
572 | dptr += hdr->len; | |
573 | else | |
574 | continue; | |
575 | ||
576 | *matchoff = dptr - start; | |
577 | if (hdr->search) { | |
578 | dptr = ct_sdp_header_search(dptr, limit, hdr->search, | |
579 | hdr->slen); | |
580 | if (!dptr) | |
581 | return -1; | |
582 | dptr += hdr->slen; | |
583 | } | |
584 | ||
585 | *matchlen = hdr->match_len(ct, dptr, limit, &shift); | |
586 | if (!*matchlen) | |
587 | return -1; | |
588 | *matchoff = dptr - start + shift; | |
589 | return 1; | |
590 | } | |
591 | return 0; | |
592 | } | |
593 | EXPORT_SYMBOL_GPL(ct_sip_get_sdp_header); | |
594 | ||
9467ee38 PM |
595 | static void flush_expectations(struct nf_conn *ct) |
596 | { | |
597 | struct nf_conn_help *help = nfct_help(ct); | |
598 | struct nf_conntrack_expect *exp; | |
599 | struct hlist_node *n, *next; | |
600 | ||
601 | spin_lock_bh(&nf_conntrack_lock); | |
602 | hlist_for_each_entry_safe(exp, n, next, &help->expectations, lnode) { | |
603 | if (!del_timer(&exp->timeout)) | |
604 | continue; | |
605 | nf_ct_unlink_expect(exp); | |
606 | nf_ct_expect_put(exp); | |
607 | } | |
608 | spin_unlock_bh(&nf_conntrack_lock); | |
609 | } | |
610 | ||
3db05fea | 611 | static int set_expected_rtp(struct sk_buff *skb, |
212440a7 PM |
612 | const char **dptr, unsigned int *datalen, |
613 | union nf_inet_addr *addr, __be16 port) | |
9fafcd7b PM |
614 | { |
615 | struct nf_conntrack_expect *exp; | |
212440a7 PM |
616 | enum ip_conntrack_info ctinfo; |
617 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
9fafcd7b PM |
618 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); |
619 | int family = ct->tuplehash[!dir].tuple.src.l3num; | |
620 | int ret; | |
621 | typeof(nf_nat_sdp_hook) nf_nat_sdp; | |
622 | ||
6823645d | 623 | exp = nf_ct_expect_alloc(ct); |
9fafcd7b PM |
624 | if (exp == NULL) |
625 | return NF_DROP; | |
6002f266 | 626 | nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, family, |
6823645d PM |
627 | &ct->tuplehash[!dir].tuple.src.u3, addr, |
628 | IPPROTO_UDP, NULL, &port); | |
9fafcd7b PM |
629 | |
630 | nf_nat_sdp = rcu_dereference(nf_nat_sdp_hook); | |
631 | if (nf_nat_sdp && ct->status & IPS_NAT_MASK) | |
212440a7 | 632 | ret = nf_nat_sdp(skb, dptr, datalen, exp); |
9fafcd7b | 633 | else { |
6823645d | 634 | if (nf_ct_expect_related(exp) != 0) |
9fafcd7b PM |
635 | ret = NF_DROP; |
636 | else | |
637 | ret = NF_ACCEPT; | |
638 | } | |
6823645d | 639 | nf_ct_expect_put(exp); |
9fafcd7b PM |
640 | |
641 | return ret; | |
642 | } | |
643 | ||
7d3dd043 | 644 | static int process_sdp(struct sk_buff *skb, |
30f33e6d PM |
645 | const char **dptr, unsigned int *datalen, |
646 | unsigned int cseq) | |
7d3dd043 PM |
647 | { |
648 | enum ip_conntrack_info ctinfo; | |
649 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
650 | int family = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num; | |
651 | unsigned int matchoff, matchlen; | |
652 | union nf_inet_addr addr; | |
653 | unsigned int port; | |
654 | enum sdp_header_types type; | |
655 | ||
656 | /* Get address and port from SDP packet. */ | |
657 | type = family == AF_INET ? SDP_HDR_CONNECTION_IP4 : | |
658 | SDP_HDR_CONNECTION_IP6; | |
659 | ||
660 | if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen, | |
661 | type, SDP_HDR_UNSPEC, | |
662 | &matchoff, &matchlen) <= 0) | |
663 | return NF_ACCEPT; | |
664 | ||
665 | /* We'll drop only if there are parse problems. */ | |
666 | if (!parse_addr(ct, *dptr + matchoff, NULL, &addr, *dptr + *datalen)) | |
667 | return NF_DROP; | |
668 | ||
669 | if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen, | |
670 | SDP_HDR_MEDIA, SDP_HDR_UNSPEC, | |
671 | &matchoff, &matchlen) <= 0) | |
672 | return NF_ACCEPT; | |
673 | ||
674 | port = simple_strtoul(*dptr + matchoff, NULL, 10); | |
675 | if (port < 1024 || port > 65535) | |
676 | return NF_DROP; | |
677 | ||
678 | return set_expected_rtp(skb, dptr, datalen, &addr, htons(port)); | |
679 | } | |
30f33e6d PM |
680 | static int process_invite_response(struct sk_buff *skb, |
681 | const char **dptr, unsigned int *datalen, | |
682 | unsigned int cseq, unsigned int code) | |
683 | { | |
9467ee38 PM |
684 | enum ip_conntrack_info ctinfo; |
685 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
686 | ||
30f33e6d PM |
687 | if ((code >= 100 && code <= 199) || |
688 | (code >= 200 && code <= 299)) | |
689 | return process_sdp(skb, dptr, datalen, cseq); | |
9467ee38 PM |
690 | else { |
691 | flush_expectations(ct); | |
692 | return NF_ACCEPT; | |
693 | } | |
30f33e6d PM |
694 | } |
695 | ||
696 | static int process_update_response(struct sk_buff *skb, | |
697 | const char **dptr, unsigned int *datalen, | |
698 | unsigned int cseq, unsigned int code) | |
699 | { | |
9467ee38 PM |
700 | enum ip_conntrack_info ctinfo; |
701 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
702 | ||
30f33e6d PM |
703 | if ((code >= 100 && code <= 199) || |
704 | (code >= 200 && code <= 299)) | |
705 | return process_sdp(skb, dptr, datalen, cseq); | |
9467ee38 PM |
706 | else { |
707 | flush_expectations(ct); | |
708 | return NF_ACCEPT; | |
709 | } | |
30f33e6d PM |
710 | } |
711 | ||
595a8ecb PM |
712 | static int process_prack_response(struct sk_buff *skb, |
713 | const char **dptr, unsigned int *datalen, | |
714 | unsigned int cseq, unsigned int code) | |
715 | { | |
9467ee38 PM |
716 | enum ip_conntrack_info ctinfo; |
717 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
718 | ||
595a8ecb PM |
719 | if ((code >= 100 && code <= 199) || |
720 | (code >= 200 && code <= 299)) | |
721 | return process_sdp(skb, dptr, datalen, cseq); | |
9467ee38 PM |
722 | else { |
723 | flush_expectations(ct); | |
724 | return NF_ACCEPT; | |
725 | } | |
726 | } | |
727 | ||
728 | static int process_bye_request(struct sk_buff *skb, | |
729 | const char **dptr, unsigned int *datalen, | |
730 | unsigned int cseq) | |
731 | { | |
732 | enum ip_conntrack_info ctinfo; | |
733 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
595a8ecb | 734 | |
9467ee38 | 735 | flush_expectations(ct); |
595a8ecb PM |
736 | return NF_ACCEPT; |
737 | } | |
738 | ||
30f33e6d PM |
739 | static const struct sip_handler sip_handlers[] = { |
740 | SIP_HANDLER("INVITE", process_sdp, process_invite_response), | |
741 | SIP_HANDLER("UPDATE", process_sdp, process_update_response), | |
595a8ecb PM |
742 | SIP_HANDLER("ACK", process_sdp, NULL), |
743 | SIP_HANDLER("PRACK", process_sdp, process_prack_response), | |
9467ee38 | 744 | SIP_HANDLER("BYE", process_bye_request, NULL), |
30f33e6d PM |
745 | }; |
746 | ||
747 | static int process_sip_response(struct sk_buff *skb, | |
748 | const char **dptr, unsigned int *datalen) | |
749 | { | |
750 | static const struct sip_handler *handler; | |
751 | enum ip_conntrack_info ctinfo; | |
752 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
753 | unsigned int matchoff, matchlen; | |
754 | unsigned int code, cseq, dataoff, i; | |
755 | ||
756 | if (*datalen < strlen("SIP/2.0 200")) | |
757 | return NF_ACCEPT; | |
758 | code = simple_strtoul(*dptr + strlen("SIP/2.0 "), NULL, 10); | |
759 | if (!code) | |
760 | return NF_DROP; | |
761 | ||
762 | if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CSEQ, | |
763 | &matchoff, &matchlen) <= 0) | |
764 | return NF_DROP; | |
765 | cseq = simple_strtoul(*dptr + matchoff, NULL, 10); | |
766 | if (!cseq) | |
767 | return NF_DROP; | |
768 | dataoff = matchoff + matchlen + 1; | |
769 | ||
770 | for (i = 0; i < ARRAY_SIZE(sip_handlers); i++) { | |
771 | handler = &sip_handlers[i]; | |
772 | if (handler->response == NULL) | |
773 | continue; | |
774 | if (*datalen < dataoff + handler->len || | |
775 | strnicmp(*dptr + dataoff, handler->method, handler->len)) | |
776 | continue; | |
777 | return handler->response(skb, dptr, datalen, cseq, code); | |
778 | } | |
779 | return NF_ACCEPT; | |
780 | } | |
781 | ||
782 | static int process_sip_request(struct sk_buff *skb, | |
783 | const char **dptr, unsigned int *datalen) | |
784 | { | |
785 | static const struct sip_handler *handler; | |
786 | enum ip_conntrack_info ctinfo; | |
787 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
788 | unsigned int matchoff, matchlen; | |
789 | unsigned int cseq, i; | |
790 | ||
791 | for (i = 0; i < ARRAY_SIZE(sip_handlers); i++) { | |
792 | handler = &sip_handlers[i]; | |
793 | if (handler->request == NULL) | |
794 | continue; | |
795 | if (*datalen < handler->len || | |
796 | strnicmp(*dptr, handler->method, handler->len)) | |
797 | continue; | |
798 | ||
799 | if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CSEQ, | |
800 | &matchoff, &matchlen) <= 0) | |
801 | return NF_DROP; | |
802 | cseq = simple_strtoul(*dptr + matchoff, NULL, 10); | |
803 | if (!cseq) | |
804 | return NF_DROP; | |
805 | ||
806 | return handler->request(skb, dptr, datalen, cseq); | |
807 | } | |
808 | return NF_ACCEPT; | |
809 | } | |
7d3dd043 | 810 | |
3db05fea | 811 | static int sip_help(struct sk_buff *skb, |
9fafcd7b PM |
812 | unsigned int protoff, |
813 | struct nf_conn *ct, | |
814 | enum ip_conntrack_info ctinfo) | |
815 | { | |
9fafcd7b PM |
816 | unsigned int dataoff, datalen; |
817 | const char *dptr; | |
33cb1e9a | 818 | int ret; |
9fafcd7b PM |
819 | typeof(nf_nat_sip_hook) nf_nat_sip; |
820 | ||
821 | /* No Data ? */ | |
822 | dataoff = protoff + sizeof(struct udphdr); | |
3db05fea | 823 | if (dataoff >= skb->len) |
9fafcd7b PM |
824 | return NF_ACCEPT; |
825 | ||
3db05fea | 826 | nf_ct_refresh(ct, skb, sip_timeout * HZ); |
9fafcd7b | 827 | |
3db05fea HX |
828 | if (!skb_is_nonlinear(skb)) |
829 | dptr = skb->data + dataoff; | |
9fafcd7b | 830 | else { |
0d53778e | 831 | pr_debug("Copy of skbuff not supported yet.\n"); |
7d3dd043 | 832 | return NF_ACCEPT; |
9fafcd7b PM |
833 | } |
834 | ||
3db05fea | 835 | datalen = skb->len - dataoff; |
779382eb | 836 | if (datalen < strlen("SIP/2.0 200")) |
7d3dd043 | 837 | return NF_ACCEPT; |
9fafcd7b | 838 | |
30f33e6d | 839 | if (strnicmp(dptr, "SIP/2.0 ", strlen("SIP/2.0 ")) != 0) |
33cb1e9a | 840 | ret = process_sip_request(skb, &dptr, &datalen); |
30f33e6d | 841 | else |
33cb1e9a PM |
842 | ret = process_sip_response(skb, &dptr, &datalen); |
843 | ||
844 | if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) { | |
845 | nf_nat_sip = rcu_dereference(nf_nat_sip_hook); | |
846 | if (nf_nat_sip && !nf_nat_sip(skb, &dptr, &datalen)) | |
847 | ret = NF_DROP; | |
848 | } | |
849 | ||
850 | return ret; | |
9fafcd7b PM |
851 | } |
852 | ||
853 | static struct nf_conntrack_helper sip[MAX_PORTS][2] __read_mostly; | |
854 | static char sip_names[MAX_PORTS][2][sizeof("sip-65535")] __read_mostly; | |
855 | ||
6002f266 PM |
856 | static const struct nf_conntrack_expect_policy sip_exp_policy = { |
857 | .max_expected = 2, | |
858 | .timeout = 3 * 60, | |
859 | }; | |
860 | ||
9fafcd7b PM |
861 | static void nf_conntrack_sip_fini(void) |
862 | { | |
863 | int i, j; | |
864 | ||
865 | for (i = 0; i < ports_c; i++) { | |
866 | for (j = 0; j < 2; j++) { | |
867 | if (sip[i][j].me == NULL) | |
868 | continue; | |
869 | nf_conntrack_helper_unregister(&sip[i][j]); | |
870 | } | |
871 | } | |
872 | } | |
873 | ||
874 | static int __init nf_conntrack_sip_init(void) | |
875 | { | |
876 | int i, j, ret; | |
877 | char *tmpname; | |
878 | ||
879 | if (ports_c == 0) | |
880 | ports[ports_c++] = SIP_PORT; | |
881 | ||
882 | for (i = 0; i < ports_c; i++) { | |
883 | memset(&sip[i], 0, sizeof(sip[i])); | |
884 | ||
885 | sip[i][0].tuple.src.l3num = AF_INET; | |
886 | sip[i][1].tuple.src.l3num = AF_INET6; | |
887 | for (j = 0; j < 2; j++) { | |
888 | sip[i][j].tuple.dst.protonum = IPPROTO_UDP; | |
889 | sip[i][j].tuple.src.u.udp.port = htons(ports[i]); | |
6002f266 | 890 | sip[i][j].expect_policy = &sip_exp_policy; |
9fafcd7b PM |
891 | sip[i][j].me = THIS_MODULE; |
892 | sip[i][j].help = sip_help; | |
893 | ||
894 | tmpname = &sip_names[i][j][0]; | |
895 | if (ports[i] == SIP_PORT) | |
896 | sprintf(tmpname, "sip"); | |
897 | else | |
898 | sprintf(tmpname, "sip-%u", i); | |
899 | sip[i][j].name = tmpname; | |
900 | ||
0d53778e | 901 | pr_debug("port #%u: %u\n", i, ports[i]); |
9fafcd7b PM |
902 | |
903 | ret = nf_conntrack_helper_register(&sip[i][j]); | |
904 | if (ret) { | |
905 | printk("nf_ct_sip: failed to register helper " | |
906 | "for pf: %u port: %u\n", | |
907 | sip[i][j].tuple.src.l3num, ports[i]); | |
908 | nf_conntrack_sip_fini(); | |
909 | return ret; | |
910 | } | |
911 | } | |
912 | } | |
913 | return 0; | |
914 | } | |
915 | ||
916 | module_init(nf_conntrack_sip_init); | |
917 | module_exit(nf_conntrack_sip_fini); |