diff options
Diffstat (limited to 'net/netfilter/nf_nat_sip.c')
-rw-r--r-- | net/netfilter/nf_nat_sip.c | 612 |
1 files changed, 612 insertions, 0 deletions
diff --git a/net/netfilter/nf_nat_sip.c b/net/netfilter/nf_nat_sip.c new file mode 100644 index 00000000000..16303c75221 --- /dev/null +++ b/net/netfilter/nf_nat_sip.c | |||
@@ -0,0 +1,612 @@ | |||
1 | /* SIP extension for NAT alteration. | ||
2 | * | ||
3 | * (C) 2005 by Christian Hentschel <chentschel@arnet.com.ar> | ||
4 | * based on RR's ip_nat_ftp.c and other modules. | ||
5 | * (C) 2007 United Security Providers | ||
6 | * (C) 2007, 2008, 2011, 2012 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/skbuff.h> | ||
15 | #include <linux/inet.h> | ||
16 | #include <linux/udp.h> | ||
17 | #include <linux/tcp.h> | ||
18 | |||
19 | #include <net/netfilter/nf_nat.h> | ||
20 | #include <net/netfilter/nf_nat_helper.h> | ||
21 | #include <net/netfilter/nf_conntrack_helper.h> | ||
22 | #include <net/netfilter/nf_conntrack_expect.h> | ||
23 | #include <linux/netfilter/nf_conntrack_sip.h> | ||
24 | |||
25 | MODULE_LICENSE("GPL"); | ||
26 | MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>"); | ||
27 | MODULE_DESCRIPTION("SIP NAT helper"); | ||
28 | MODULE_ALIAS("ip_nat_sip"); | ||
29 | |||
30 | |||
31 | static unsigned int mangle_packet(struct sk_buff *skb, unsigned int protoff, | ||
32 | unsigned int dataoff, | ||
33 | const char **dptr, unsigned int *datalen, | ||
34 | unsigned int matchoff, unsigned int matchlen, | ||
35 | const char *buffer, unsigned int buflen) | ||
36 | { | ||
37 | enum ip_conntrack_info ctinfo; | ||
38 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | ||
39 | struct tcphdr *th; | ||
40 | unsigned int baseoff; | ||
41 | |||
42 | if (nf_ct_protonum(ct) == IPPROTO_TCP) { | ||
43 | th = (struct tcphdr *)(skb->data + protoff); | ||
44 | baseoff = protoff + th->doff * 4; | ||
45 | matchoff += dataoff - baseoff; | ||
46 | |||
47 | if (!__nf_nat_mangle_tcp_packet(skb, ct, ctinfo, | ||
48 | protoff, matchoff, matchlen, | ||
49 | buffer, buflen, false)) | ||
50 | return 0; | ||
51 | } else { | ||
52 | baseoff = protoff + sizeof(struct udphdr); | ||
53 | matchoff += dataoff - baseoff; | ||
54 | |||
55 | if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo, | ||
56 | protoff, matchoff, matchlen, | ||
57 | buffer, buflen)) | ||
58 | return 0; | ||
59 | } | ||
60 | |||
61 | /* Reload data pointer and adjust datalen value */ | ||
62 | *dptr = skb->data + dataoff; | ||
63 | *datalen += buflen - matchlen; | ||
64 | return 1; | ||
65 | } | ||
66 | |||
67 | static int sip_sprintf_addr(const struct nf_conn *ct, char *buffer, | ||
68 | const union nf_inet_addr *addr, bool delim) | ||
69 | { | ||
70 | if (nf_ct_l3num(ct) == NFPROTO_IPV4) | ||
71 | return sprintf(buffer, "%pI4", &addr->ip); | ||
72 | else { | ||
73 | if (delim) | ||
74 | return sprintf(buffer, "[%pI6c]", &addr->ip6); | ||
75 | else | ||
76 | return sprintf(buffer, "%pI6c", &addr->ip6); | ||
77 | } | ||
78 | } | ||
79 | |||
80 | static int sip_sprintf_addr_port(const struct nf_conn *ct, char *buffer, | ||
81 | const union nf_inet_addr *addr, u16 port) | ||
82 | { | ||
83 | if (nf_ct_l3num(ct) == NFPROTO_IPV4) | ||
84 | return sprintf(buffer, "%pI4:%u", &addr->ip, port); | ||
85 | else | ||
86 | return sprintf(buffer, "[%pI6c]:%u", &addr->ip6, port); | ||
87 | } | ||
88 | |||
89 | static int map_addr(struct sk_buff *skb, unsigned int protoff, | ||
90 | unsigned int dataoff, | ||
91 | const char **dptr, unsigned int *datalen, | ||
92 | unsigned int matchoff, unsigned int matchlen, | ||
93 | union nf_inet_addr *addr, __be16 port) | ||
94 | { | ||
95 | enum ip_conntrack_info ctinfo; | ||
96 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | ||
97 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); | ||
98 | char buffer[INET6_ADDRSTRLEN + sizeof("[]:nnnnn")]; | ||
99 | unsigned int buflen; | ||
100 | union nf_inet_addr newaddr; | ||
101 | __be16 newport; | ||
102 | |||
103 | if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3, addr) && | ||
104 | ct->tuplehash[dir].tuple.src.u.udp.port == port) { | ||
105 | newaddr = ct->tuplehash[!dir].tuple.dst.u3; | ||
106 | newport = ct->tuplehash[!dir].tuple.dst.u.udp.port; | ||
107 | } else if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3, addr) && | ||
108 | ct->tuplehash[dir].tuple.dst.u.udp.port == port) { | ||
109 | newaddr = ct->tuplehash[!dir].tuple.src.u3; | ||
110 | newport = ct->tuplehash[!dir].tuple.src.u.udp.port; | ||
111 | } else | ||
112 | return 1; | ||
113 | |||
114 | if (nf_inet_addr_cmp(&newaddr, addr) && newport == port) | ||
115 | return 1; | ||
116 | |||
117 | buflen = sip_sprintf_addr_port(ct, buffer, &newaddr, ntohs(newport)); | ||
118 | return mangle_packet(skb, protoff, dataoff, dptr, datalen, | ||
119 | matchoff, matchlen, buffer, buflen); | ||
120 | } | ||
121 | |||
122 | static int map_sip_addr(struct sk_buff *skb, unsigned int protoff, | ||
123 | unsigned int dataoff, | ||
124 | const char **dptr, unsigned int *datalen, | ||
125 | enum sip_header_types type) | ||
126 | { | ||
127 | enum ip_conntrack_info ctinfo; | ||
128 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | ||
129 | unsigned int matchlen, matchoff; | ||
130 | union nf_inet_addr addr; | ||
131 | __be16 port; | ||
132 | |||
133 | if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen, type, NULL, | ||
134 | &matchoff, &matchlen, &addr, &port) <= 0) | ||
135 | return 1; | ||
136 | return map_addr(skb, protoff, dataoff, dptr, datalen, | ||
137 | matchoff, matchlen, &addr, port); | ||
138 | } | ||
139 | |||
140 | static unsigned int nf_nat_sip(struct sk_buff *skb, unsigned int protoff, | ||
141 | unsigned int dataoff, | ||
142 | const char **dptr, unsigned int *datalen) | ||
143 | { | ||
144 | enum ip_conntrack_info ctinfo; | ||
145 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | ||
146 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); | ||
147 | unsigned int coff, matchoff, matchlen; | ||
148 | enum sip_header_types hdr; | ||
149 | union nf_inet_addr addr; | ||
150 | __be16 port; | ||
151 | int request, in_header; | ||
152 | |||
153 | /* Basic rules: requests and responses. */ | ||
154 | if (strnicmp(*dptr, "SIP/2.0", strlen("SIP/2.0")) != 0) { | ||
155 | if (ct_sip_parse_request(ct, *dptr, *datalen, | ||
156 | &matchoff, &matchlen, | ||
157 | &addr, &port) > 0 && | ||
158 | !map_addr(skb, protoff, dataoff, dptr, datalen, | ||
159 | matchoff, matchlen, &addr, port)) | ||
160 | return NF_DROP; | ||
161 | request = 1; | ||
162 | } else | ||
163 | request = 0; | ||
164 | |||
165 | if (nf_ct_protonum(ct) == IPPROTO_TCP) | ||
166 | hdr = SIP_HDR_VIA_TCP; | ||
167 | else | ||
168 | hdr = SIP_HDR_VIA_UDP; | ||
169 | |||
170 | /* Translate topmost Via header and parameters */ | ||
171 | if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen, | ||
172 | hdr, NULL, &matchoff, &matchlen, | ||
173 | &addr, &port) > 0) { | ||
174 | unsigned int olen, matchend, poff, plen, buflen, n; | ||
175 | char buffer[INET6_ADDRSTRLEN + sizeof("[]:nnnnn")]; | ||
176 | |||
177 | /* We're only interested in headers related to this | ||
178 | * connection */ | ||
179 | if (request) { | ||
180 | if (!nf_inet_addr_cmp(&addr, | ||
181 | &ct->tuplehash[dir].tuple.src.u3) || | ||
182 | port != ct->tuplehash[dir].tuple.src.u.udp.port) | ||
183 | goto next; | ||
184 | } else { | ||
185 | if (!nf_inet_addr_cmp(&addr, | ||
186 | &ct->tuplehash[dir].tuple.dst.u3) || | ||
187 | port != ct->tuplehash[dir].tuple.dst.u.udp.port) | ||
188 | goto next; | ||
189 | } | ||
190 | |||
191 | olen = *datalen; | ||
192 | if (!map_addr(skb, protoff, dataoff, dptr, datalen, | ||
193 | matchoff, matchlen, &addr, port)) | ||
194 | return NF_DROP; | ||
195 | |||
196 | matchend = matchoff + matchlen + *datalen - olen; | ||
197 | |||
198 | /* The maddr= parameter (RFC 2361) specifies where to send | ||
199 | * the reply. */ | ||
200 | if (ct_sip_parse_address_param(ct, *dptr, matchend, *datalen, | ||
201 | "maddr=", &poff, &plen, | ||
202 | &addr, true) > 0 && | ||
203 | nf_inet_addr_cmp(&addr, &ct->tuplehash[dir].tuple.src.u3) && | ||
204 | !nf_inet_addr_cmp(&addr, &ct->tuplehash[!dir].tuple.dst.u3)) { | ||
205 | buflen = sip_sprintf_addr(ct, buffer, | ||
206 | &ct->tuplehash[!dir].tuple.dst.u3, | ||
207 | true); | ||
208 | if (!mangle_packet(skb, protoff, dataoff, dptr, datalen, | ||
209 | poff, plen, buffer, buflen)) | ||
210 | return NF_DROP; | ||
211 | } | ||
212 | |||
213 | /* The received= parameter (RFC 2361) contains the address | ||
214 | * from which the server received the request. */ | ||
215 | if (ct_sip_parse_address_param(ct, *dptr, matchend, *datalen, | ||
216 | "received=", &poff, &plen, | ||
217 | &addr, false) > 0 && | ||
218 | nf_inet_addr_cmp(&addr, &ct->tuplehash[dir].tuple.dst.u3) && | ||
219 | !nf_inet_addr_cmp(&addr, &ct->tuplehash[!dir].tuple.src.u3)) { | ||
220 | buflen = sip_sprintf_addr(ct, buffer, | ||
221 | &ct->tuplehash[!dir].tuple.src.u3, | ||
222 | false); | ||
223 | if (!mangle_packet(skb, protoff, dataoff, dptr, datalen, | ||
224 | poff, plen, buffer, buflen)) | ||
225 | return NF_DROP; | ||
226 | } | ||
227 | |||
228 | /* The rport= parameter (RFC 3581) contains the port number | ||
229 | * from which the server received the request. */ | ||
230 | if (ct_sip_parse_numerical_param(ct, *dptr, matchend, *datalen, | ||
231 | "rport=", &poff, &plen, | ||
232 | &n) > 0 && | ||
233 | htons(n) == ct->tuplehash[dir].tuple.dst.u.udp.port && | ||
234 | htons(n) != ct->tuplehash[!dir].tuple.src.u.udp.port) { | ||
235 | __be16 p = ct->tuplehash[!dir].tuple.src.u.udp.port; | ||
236 | buflen = sprintf(buffer, "%u", ntohs(p)); | ||
237 | if (!mangle_packet(skb, protoff, dataoff, dptr, datalen, | ||
238 | poff, plen, buffer, buflen)) | ||
239 | return NF_DROP; | ||
240 | } | ||
241 | } | ||
242 | |||
243 | next: | ||
244 | /* Translate Contact headers */ | ||
245 | coff = 0; | ||
246 | in_header = 0; | ||
247 | while (ct_sip_parse_header_uri(ct, *dptr, &coff, *datalen, | ||
248 | SIP_HDR_CONTACT, &in_header, | ||
249 | &matchoff, &matchlen, | ||
250 | &addr, &port) > 0) { | ||
251 | if (!map_addr(skb, protoff, dataoff, dptr, datalen, | ||
252 | matchoff, matchlen, | ||
253 | &addr, port)) | ||
254 | return NF_DROP; | ||
255 | } | ||
256 | |||
257 | if (!map_sip_addr(skb, protoff, dataoff, dptr, datalen, SIP_HDR_FROM) || | ||
258 | !map_sip_addr(skb, protoff, dataoff, dptr, datalen, SIP_HDR_TO)) | ||
259 | return NF_DROP; | ||
260 | |||
261 | return NF_ACCEPT; | ||
262 | } | ||
263 | |||
264 | static void nf_nat_sip_seq_adjust(struct sk_buff *skb, unsigned int protoff, | ||
265 | s16 off) | ||
266 | { | ||
267 | enum ip_conntrack_info ctinfo; | ||
268 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | ||
269 | const struct tcphdr *th; | ||
270 | |||
271 | if (nf_ct_protonum(ct) != IPPROTO_TCP || off == 0) | ||
272 | return; | ||
273 | |||
274 | th = (struct tcphdr *)(skb->data + protoff); | ||
275 | nf_nat_set_seq_adjust(ct, ctinfo, th->seq, off); | ||
276 | } | ||
277 | |||
278 | /* Handles expected signalling connections and media streams */ | ||
279 | static void nf_nat_sip_expected(struct nf_conn *ct, | ||
280 | struct nf_conntrack_expect *exp) | ||
281 | { | ||
282 | struct nf_nat_range range; | ||
283 | |||
284 | /* This must be a fresh one. */ | ||
285 | BUG_ON(ct->status & IPS_NAT_DONE_MASK); | ||
286 | |||
287 | /* For DST manip, map port here to where it's expected. */ | ||
288 | range.flags = (NF_NAT_RANGE_MAP_IPS | NF_NAT_RANGE_PROTO_SPECIFIED); | ||
289 | range.min_proto = range.max_proto = exp->saved_proto; | ||
290 | range.min_addr = range.max_addr = exp->saved_addr; | ||
291 | nf_nat_setup_info(ct, &range, NF_NAT_MANIP_DST); | ||
292 | |||
293 | /* Change src to where master sends to, but only if the connection | ||
294 | * actually came from the same source. */ | ||
295 | if (nf_inet_addr_cmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3, | ||
296 | &ct->master->tuplehash[exp->dir].tuple.src.u3)) { | ||
297 | range.flags = NF_NAT_RANGE_MAP_IPS; | ||
298 | range.min_addr = range.max_addr | ||
299 | = ct->master->tuplehash[!exp->dir].tuple.dst.u3; | ||
300 | nf_nat_setup_info(ct, &range, NF_NAT_MANIP_SRC); | ||
301 | } | ||
302 | } | ||
303 | |||
304 | static unsigned int nf_nat_sip_expect(struct sk_buff *skb, unsigned int protoff, | ||
305 | unsigned int dataoff, | ||
306 | const char **dptr, unsigned int *datalen, | ||
307 | struct nf_conntrack_expect *exp, | ||
308 | unsigned int matchoff, | ||
309 | unsigned int matchlen) | ||
310 | { | ||
311 | enum ip_conntrack_info ctinfo; | ||
312 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | ||
313 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); | ||
314 | union nf_inet_addr newaddr; | ||
315 | u_int16_t port; | ||
316 | char buffer[INET6_ADDRSTRLEN + sizeof("[]:nnnnn")]; | ||
317 | unsigned int buflen; | ||
318 | |||
319 | /* Connection will come from reply */ | ||
320 | if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3, | ||
321 | &ct->tuplehash[!dir].tuple.dst.u3)) | ||
322 | newaddr = exp->tuple.dst.u3; | ||
323 | else | ||
324 | newaddr = ct->tuplehash[!dir].tuple.dst.u3; | ||
325 | |||
326 | /* If the signalling port matches the connection's source port in the | ||
327 | * original direction, try to use the destination port in the opposite | ||
328 | * direction. */ | ||
329 | if (exp->tuple.dst.u.udp.port == | ||
330 | ct->tuplehash[dir].tuple.src.u.udp.port) | ||
331 | port = ntohs(ct->tuplehash[!dir].tuple.dst.u.udp.port); | ||
332 | else | ||
333 | port = ntohs(exp->tuple.dst.u.udp.port); | ||
334 | |||
335 | exp->saved_addr = exp->tuple.dst.u3; | ||
336 | exp->tuple.dst.u3 = newaddr; | ||
337 | exp->saved_proto.udp.port = exp->tuple.dst.u.udp.port; | ||
338 | exp->dir = !dir; | ||
339 | exp->expectfn = nf_nat_sip_expected; | ||
340 | |||
341 | for (; port != 0; port++) { | ||
342 | int ret; | ||
343 | |||
344 | exp->tuple.dst.u.udp.port = htons(port); | ||
345 | ret = nf_ct_expect_related(exp); | ||
346 | if (ret == 0) | ||
347 | break; | ||
348 | else if (ret != -EBUSY) { | ||
349 | port = 0; | ||
350 | break; | ||
351 | } | ||
352 | } | ||
353 | |||
354 | if (port == 0) | ||
355 | return NF_DROP; | ||
356 | |||
357 | if (!nf_inet_addr_cmp(&exp->tuple.dst.u3, &exp->saved_addr) || | ||
358 | exp->tuple.dst.u.udp.port != exp->saved_proto.udp.port) { | ||
359 | buflen = sip_sprintf_addr_port(ct, buffer, &newaddr, port); | ||
360 | if (!mangle_packet(skb, protoff, dataoff, dptr, datalen, | ||
361 | matchoff, matchlen, buffer, buflen)) | ||
362 | goto err; | ||
363 | } | ||
364 | return NF_ACCEPT; | ||
365 | |||
366 | err: | ||
367 | nf_ct_unexpect_related(exp); | ||
368 | return NF_DROP; | ||
369 | } | ||
370 | |||
371 | static int mangle_content_len(struct sk_buff *skb, unsigned int protoff, | ||
372 | unsigned int dataoff, | ||
373 | const char **dptr, unsigned int *datalen) | ||
374 | { | ||
375 | enum ip_conntrack_info ctinfo; | ||
376 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | ||
377 | unsigned int matchoff, matchlen; | ||
378 | char buffer[sizeof("65536")]; | ||
379 | int buflen, c_len; | ||
380 | |||
381 | /* Get actual SDP length */ | ||
382 | if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen, | ||
383 | SDP_HDR_VERSION, SDP_HDR_UNSPEC, | ||
384 | &matchoff, &matchlen) <= 0) | ||
385 | return 0; | ||
386 | c_len = *datalen - matchoff + strlen("v="); | ||
387 | |||
388 | /* Now, update SDP length */ | ||
389 | if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CONTENT_LENGTH, | ||
390 | &matchoff, &matchlen) <= 0) | ||
391 | return 0; | ||
392 | |||
393 | buflen = sprintf(buffer, "%u", c_len); | ||
394 | return mangle_packet(skb, protoff, dataoff, dptr, datalen, | ||
395 | matchoff, matchlen, buffer, buflen); | ||
396 | } | ||
397 | |||
398 | static int mangle_sdp_packet(struct sk_buff *skb, unsigned int protoff, | ||
399 | unsigned int dataoff, | ||
400 | const char **dptr, unsigned int *datalen, | ||
401 | unsigned int sdpoff, | ||
402 | enum sdp_header_types type, | ||
403 | enum sdp_header_types term, | ||
404 | char *buffer, int buflen) | ||
405 | { | ||
406 | enum ip_conntrack_info ctinfo; | ||
407 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | ||
408 | unsigned int matchlen, matchoff; | ||
409 | |||
410 | if (ct_sip_get_sdp_header(ct, *dptr, sdpoff, *datalen, type, term, | ||
411 | &matchoff, &matchlen) <= 0) | ||
412 | return -ENOENT; | ||
413 | return mangle_packet(skb, protoff, dataoff, dptr, datalen, | ||
414 | matchoff, matchlen, buffer, buflen) ? 0 : -EINVAL; | ||
415 | } | ||
416 | |||
417 | static unsigned int nf_nat_sdp_addr(struct sk_buff *skb, unsigned int protoff, | ||
418 | unsigned int dataoff, | ||
419 | const char **dptr, unsigned int *datalen, | ||
420 | unsigned int sdpoff, | ||
421 | enum sdp_header_types type, | ||
422 | enum sdp_header_types term, | ||
423 | const union nf_inet_addr *addr) | ||
424 | { | ||
425 | enum ip_conntrack_info ctinfo; | ||
426 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | ||
427 | char buffer[INET6_ADDRSTRLEN]; | ||
428 | unsigned int buflen; | ||
429 | |||
430 | buflen = sip_sprintf_addr(ct, buffer, addr, false); | ||
431 | if (mangle_sdp_packet(skb, protoff, dataoff, dptr, datalen, | ||
432 | sdpoff, type, term, buffer, buflen)) | ||
433 | return 0; | ||
434 | |||
435 | return mangle_content_len(skb, protoff, dataoff, dptr, datalen); | ||
436 | } | ||
437 | |||
438 | static unsigned int nf_nat_sdp_port(struct sk_buff *skb, unsigned int protoff, | ||
439 | unsigned int dataoff, | ||
440 | const char **dptr, unsigned int *datalen, | ||
441 | unsigned int matchoff, | ||
442 | unsigned int matchlen, | ||
443 | u_int16_t port) | ||
444 | { | ||
445 | char buffer[sizeof("nnnnn")]; | ||
446 | unsigned int buflen; | ||
447 | |||
448 | buflen = sprintf(buffer, "%u", port); | ||
449 | if (!mangle_packet(skb, protoff, dataoff, dptr, datalen, | ||
450 | matchoff, matchlen, buffer, buflen)) | ||
451 | return 0; | ||
452 | |||
453 | return mangle_content_len(skb, protoff, dataoff, dptr, datalen); | ||
454 | } | ||
455 | |||
456 | static unsigned int nf_nat_sdp_session(struct sk_buff *skb, unsigned int protoff, | ||
457 | unsigned int dataoff, | ||
458 | const char **dptr, unsigned int *datalen, | ||
459 | unsigned int sdpoff, | ||
460 | const union nf_inet_addr *addr) | ||
461 | { | ||
462 | enum ip_conntrack_info ctinfo; | ||
463 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | ||
464 | char buffer[INET6_ADDRSTRLEN]; | ||
465 | unsigned int buflen; | ||
466 | |||
467 | /* Mangle session description owner and contact addresses */ | ||
468 | buflen = sip_sprintf_addr(ct, buffer, addr, false); | ||
469 | if (mangle_sdp_packet(skb, protoff, dataoff, dptr, datalen, sdpoff, | ||
470 | SDP_HDR_OWNER, SDP_HDR_MEDIA, buffer, buflen)) | ||
471 | return 0; | ||
472 | |||
473 | switch (mangle_sdp_packet(skb, protoff, dataoff, dptr, datalen, sdpoff, | ||
474 | SDP_HDR_CONNECTION, SDP_HDR_MEDIA, | ||
475 | buffer, buflen)) { | ||
476 | case 0: | ||
477 | /* | ||
478 | * RFC 2327: | ||
479 | * | ||
480 | * Session description | ||
481 | * | ||
482 | * c=* (connection information - not required if included in all media) | ||
483 | */ | ||
484 | case -ENOENT: | ||
485 | break; | ||
486 | default: | ||
487 | return 0; | ||
488 | } | ||
489 | |||
490 | return mangle_content_len(skb, protoff, dataoff, dptr, datalen); | ||
491 | } | ||
492 | |||
493 | /* So, this packet has hit the connection tracking matching code. | ||
494 | Mangle it, and change the expectation to match the new version. */ | ||
495 | static unsigned int nf_nat_sdp_media(struct sk_buff *skb, unsigned int protoff, | ||
496 | unsigned int dataoff, | ||
497 | const char **dptr, unsigned int *datalen, | ||
498 | struct nf_conntrack_expect *rtp_exp, | ||
499 | struct nf_conntrack_expect *rtcp_exp, | ||
500 | unsigned int mediaoff, | ||
501 | unsigned int medialen, | ||
502 | union nf_inet_addr *rtp_addr) | ||
503 | { | ||
504 | enum ip_conntrack_info ctinfo; | ||
505 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | ||
506 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); | ||
507 | u_int16_t port; | ||
508 | |||
509 | /* Connection will come from reply */ | ||
510 | if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3, | ||
511 | &ct->tuplehash[!dir].tuple.dst.u3)) | ||
512 | *rtp_addr = rtp_exp->tuple.dst.u3; | ||
513 | else | ||
514 | *rtp_addr = ct->tuplehash[!dir].tuple.dst.u3; | ||
515 | |||
516 | rtp_exp->saved_addr = rtp_exp->tuple.dst.u3; | ||
517 | rtp_exp->tuple.dst.u3 = *rtp_addr; | ||
518 | rtp_exp->saved_proto.udp.port = rtp_exp->tuple.dst.u.udp.port; | ||
519 | rtp_exp->dir = !dir; | ||
520 | rtp_exp->expectfn = nf_nat_sip_expected; | ||
521 | |||
522 | rtcp_exp->saved_addr = rtcp_exp->tuple.dst.u3; | ||
523 | rtcp_exp->tuple.dst.u3 = *rtp_addr; | ||
524 | rtcp_exp->saved_proto.udp.port = rtcp_exp->tuple.dst.u.udp.port; | ||
525 | rtcp_exp->dir = !dir; | ||
526 | rtcp_exp->expectfn = nf_nat_sip_expected; | ||
527 | |||
528 | /* Try to get same pair of ports: if not, try to change them. */ | ||
529 | for (port = ntohs(rtp_exp->tuple.dst.u.udp.port); | ||
530 | port != 0; port += 2) { | ||
531 | int ret; | ||
532 | |||
533 | rtp_exp->tuple.dst.u.udp.port = htons(port); | ||
534 | ret = nf_ct_expect_related(rtp_exp); | ||
535 | if (ret == -EBUSY) | ||
536 | continue; | ||
537 | else if (ret < 0) { | ||
538 | port = 0; | ||
539 | break; | ||
540 | } | ||
541 | rtcp_exp->tuple.dst.u.udp.port = htons(port + 1); | ||
542 | ret = nf_ct_expect_related(rtcp_exp); | ||
543 | if (ret == 0) | ||
544 | break; | ||
545 | else if (ret == -EBUSY) { | ||
546 | nf_ct_unexpect_related(rtp_exp); | ||
547 | continue; | ||
548 | } else if (ret < 0) { | ||
549 | nf_ct_unexpect_related(rtp_exp); | ||
550 | port = 0; | ||
551 | break; | ||
552 | } | ||
553 | } | ||
554 | |||
555 | if (port == 0) | ||
556 | goto err1; | ||
557 | |||
558 | /* Update media port. */ | ||
559 | if (rtp_exp->tuple.dst.u.udp.port != rtp_exp->saved_proto.udp.port && | ||
560 | !nf_nat_sdp_port(skb, protoff, dataoff, dptr, datalen, | ||
561 | mediaoff, medialen, port)) | ||
562 | goto err2; | ||
563 | |||
564 | return NF_ACCEPT; | ||
565 | |||
566 | err2: | ||
567 | nf_ct_unexpect_related(rtp_exp); | ||
568 | nf_ct_unexpect_related(rtcp_exp); | ||
569 | err1: | ||
570 | return NF_DROP; | ||
571 | } | ||
572 | |||
573 | static struct nf_ct_helper_expectfn sip_nat = { | ||
574 | .name = "sip", | ||
575 | .expectfn = nf_nat_sip_expected, | ||
576 | }; | ||
577 | |||
578 | static void __exit nf_nat_sip_fini(void) | ||
579 | { | ||
580 | RCU_INIT_POINTER(nf_nat_sip_hook, NULL); | ||
581 | RCU_INIT_POINTER(nf_nat_sip_seq_adjust_hook, NULL); | ||
582 | RCU_INIT_POINTER(nf_nat_sip_expect_hook, NULL); | ||
583 | RCU_INIT_POINTER(nf_nat_sdp_addr_hook, NULL); | ||
584 | RCU_INIT_POINTER(nf_nat_sdp_port_hook, NULL); | ||
585 | RCU_INIT_POINTER(nf_nat_sdp_session_hook, NULL); | ||
586 | RCU_INIT_POINTER(nf_nat_sdp_media_hook, NULL); | ||
587 | nf_ct_helper_expectfn_unregister(&sip_nat); | ||
588 | synchronize_rcu(); | ||
589 | } | ||
590 | |||
591 | static int __init nf_nat_sip_init(void) | ||
592 | { | ||
593 | BUG_ON(nf_nat_sip_hook != NULL); | ||
594 | BUG_ON(nf_nat_sip_seq_adjust_hook != NULL); | ||
595 | BUG_ON(nf_nat_sip_expect_hook != NULL); | ||
596 | BUG_ON(nf_nat_sdp_addr_hook != NULL); | ||
597 | BUG_ON(nf_nat_sdp_port_hook != NULL); | ||
598 | BUG_ON(nf_nat_sdp_session_hook != NULL); | ||
599 | BUG_ON(nf_nat_sdp_media_hook != NULL); | ||
600 | RCU_INIT_POINTER(nf_nat_sip_hook, nf_nat_sip); | ||
601 | RCU_INIT_POINTER(nf_nat_sip_seq_adjust_hook, nf_nat_sip_seq_adjust); | ||
602 | RCU_INIT_POINTER(nf_nat_sip_expect_hook, nf_nat_sip_expect); | ||
603 | RCU_INIT_POINTER(nf_nat_sdp_addr_hook, nf_nat_sdp_addr); | ||
604 | RCU_INIT_POINTER(nf_nat_sdp_port_hook, nf_nat_sdp_port); | ||
605 | RCU_INIT_POINTER(nf_nat_sdp_session_hook, nf_nat_sdp_session); | ||
606 | RCU_INIT_POINTER(nf_nat_sdp_media_hook, nf_nat_sdp_media); | ||
607 | nf_ct_helper_expectfn_register(&sip_nat); | ||
608 | return 0; | ||
609 | } | ||
610 | |||
611 | module_init(nf_nat_sip_init); | ||
612 | module_exit(nf_nat_sip_fini); | ||