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Commit | Line | Data |
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48f8ac26 | 1 | /* SIP extension for NAT alteration. |
9fafcd7b PM |
2 | * |
3 | * (C) 2005 by Christian Hentschel <chentschel@arnet.com.ar> | |
4 | * based on RR's ip_nat_ftp.c and other modules. | |
f49e1aa1 PM |
5 | * (C) 2007 United Security Providers |
6 | * (C) 2007, 2008 Patrick McHardy <kaber@trash.net> | |
9fafcd7b PM |
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/ip.h> | |
c9bdd4b5 | 16 | #include <net/ip.h> |
9fafcd7b | 17 | #include <linux/udp.h> |
48f8ac26 | 18 | #include <linux/tcp.h> |
9fafcd7b PM |
19 | |
20 | #include <net/netfilter/nf_nat.h> | |
21 | #include <net/netfilter/nf_nat_helper.h> | |
22 | #include <net/netfilter/nf_nat_rule.h> | |
23 | #include <net/netfilter/nf_conntrack_helper.h> | |
24 | #include <net/netfilter/nf_conntrack_expect.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 NAT helper"); | |
30 | MODULE_ALIAS("ip_nat_sip"); | |
31 | ||
9fafcd7b | 32 | |
3b6b9fab | 33 | static unsigned int mangle_packet(struct sk_buff *skb, unsigned int dataoff, |
2a6cfb22 PM |
34 | const char **dptr, unsigned int *datalen, |
35 | unsigned int matchoff, unsigned int matchlen, | |
36 | const char *buffer, unsigned int buflen) | |
37 | { | |
38 | enum ip_conntrack_info ctinfo; | |
39 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
48f8ac26 PM |
40 | struct tcphdr *th; |
41 | unsigned int baseoff; | |
42 | ||
43 | if (nf_ct_protonum(ct) == IPPROTO_TCP) { | |
44 | th = (struct tcphdr *)(skb->data + ip_hdrlen(skb)); | |
45 | baseoff = ip_hdrlen(skb) + th->doff * 4; | |
46 | matchoff += dataoff - baseoff; | |
47 | ||
48 | if (!__nf_nat_mangle_tcp_packet(skb, ct, ctinfo, | |
49 | matchoff, matchlen, | |
50 | buffer, buflen, false)) | |
51 | return 0; | |
52 | } else { | |
53 | baseoff = ip_hdrlen(skb) + sizeof(struct udphdr); | |
54 | matchoff += dataoff - baseoff; | |
55 | ||
56 | if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo, | |
57 | matchoff, matchlen, | |
58 | buffer, buflen)) | |
59 | return 0; | |
60 | } | |
2a6cfb22 PM |
61 | |
62 | /* Reload data pointer and adjust datalen value */ | |
3b6b9fab | 63 | *dptr = skb->data + dataoff; |
2a6cfb22 PM |
64 | *datalen += buflen - matchlen; |
65 | return 1; | |
66 | } | |
67 | ||
3b6b9fab | 68 | static int map_addr(struct sk_buff *skb, unsigned int dataoff, |
ac367740 PM |
69 | const char **dptr, unsigned int *datalen, |
70 | unsigned int matchoff, unsigned int matchlen, | |
624f8b7b | 71 | union nf_inet_addr *addr, __be16 port) |
9fafcd7b | 72 | { |
212440a7 | 73 | enum ip_conntrack_info ctinfo; |
624f8b7b | 74 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); |
9fafcd7b | 75 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); |
624f8b7b PM |
76 | char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")]; |
77 | unsigned int buflen; | |
78 | __be32 newaddr; | |
79 | __be16 newport; | |
80 | ||
81 | if (ct->tuplehash[dir].tuple.src.u3.ip == addr->ip && | |
82 | ct->tuplehash[dir].tuple.src.u.udp.port == port) { | |
83 | newaddr = ct->tuplehash[!dir].tuple.dst.u3.ip; | |
84 | newport = ct->tuplehash[!dir].tuple.dst.u.udp.port; | |
85 | } else if (ct->tuplehash[dir].tuple.dst.u3.ip == addr->ip && | |
86 | ct->tuplehash[dir].tuple.dst.u.udp.port == port) { | |
87 | newaddr = ct->tuplehash[!dir].tuple.src.u3.ip; | |
88 | newport = ct->tuplehash[!dir].tuple.src.u.udp.port; | |
9fafcd7b PM |
89 | } else |
90 | return 1; | |
91 | ||
624f8b7b PM |
92 | if (newaddr == addr->ip && newport == port) |
93 | return 1; | |
94 | ||
cffee385 | 95 | buflen = sprintf(buffer, "%pI4:%u", &newaddr, ntohs(newport)); |
624f8b7b | 96 | |
3b6b9fab | 97 | return mangle_packet(skb, dataoff, dptr, datalen, matchoff, matchlen, |
624f8b7b | 98 | buffer, buflen); |
9fafcd7b PM |
99 | } |
100 | ||
3b6b9fab | 101 | static int map_sip_addr(struct sk_buff *skb, unsigned int dataoff, |
ac367740 | 102 | const char **dptr, unsigned int *datalen, |
624f8b7b | 103 | enum sip_header_types type) |
ac367740 PM |
104 | { |
105 | enum ip_conntrack_info ctinfo; | |
106 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
107 | unsigned int matchlen, matchoff; | |
624f8b7b PM |
108 | union nf_inet_addr addr; |
109 | __be16 port; | |
ac367740 | 110 | |
624f8b7b PM |
111 | if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen, type, NULL, |
112 | &matchoff, &matchlen, &addr, &port) <= 0) | |
ac367740 | 113 | return 1; |
3b6b9fab PM |
114 | return map_addr(skb, dataoff, dptr, datalen, matchoff, matchlen, |
115 | &addr, port); | |
ac367740 PM |
116 | } |
117 | ||
3b6b9fab | 118 | static unsigned int ip_nat_sip(struct sk_buff *skb, unsigned int dataoff, |
2a6cfb22 | 119 | const char **dptr, unsigned int *datalen) |
9fafcd7b | 120 | { |
212440a7 PM |
121 | enum ip_conntrack_info ctinfo; |
122 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
720ac708 | 123 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); |
3b6b9fab | 124 | unsigned int coff, matchoff, matchlen; |
48f8ac26 | 125 | enum sip_header_types hdr; |
624f8b7b PM |
126 | union nf_inet_addr addr; |
127 | __be16 port; | |
c978cd3a | 128 | int request, in_header; |
9fafcd7b | 129 | |
9fafcd7b | 130 | /* Basic rules: requests and responses. */ |
779382eb | 131 | if (strnicmp(*dptr, "SIP/2.0", strlen("SIP/2.0")) != 0) { |
ac367740 | 132 | if (ct_sip_parse_request(ct, *dptr, *datalen, |
624f8b7b PM |
133 | &matchoff, &matchlen, |
134 | &addr, &port) > 0 && | |
3b6b9fab | 135 | !map_addr(skb, dataoff, dptr, datalen, matchoff, matchlen, |
624f8b7b | 136 | &addr, port)) |
9fafcd7b | 137 | return NF_DROP; |
720ac708 PM |
138 | request = 1; |
139 | } else | |
140 | request = 0; | |
141 | ||
48f8ac26 PM |
142 | if (nf_ct_protonum(ct) == IPPROTO_TCP) |
143 | hdr = SIP_HDR_VIA_TCP; | |
144 | else | |
145 | hdr = SIP_HDR_VIA_UDP; | |
146 | ||
720ac708 PM |
147 | /* Translate topmost Via header and parameters */ |
148 | if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen, | |
48f8ac26 | 149 | hdr, NULL, &matchoff, &matchlen, |
720ac708 PM |
150 | &addr, &port) > 0) { |
151 | unsigned int matchend, poff, plen, buflen, n; | |
152 | char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")]; | |
153 | ||
154 | /* We're only interested in headers related to this | |
155 | * connection */ | |
156 | if (request) { | |
157 | if (addr.ip != ct->tuplehash[dir].tuple.src.u3.ip || | |
158 | port != ct->tuplehash[dir].tuple.src.u.udp.port) | |
159 | goto next; | |
160 | } else { | |
161 | if (addr.ip != ct->tuplehash[dir].tuple.dst.u3.ip || | |
162 | port != ct->tuplehash[dir].tuple.dst.u.udp.port) | |
163 | goto next; | |
164 | } | |
165 | ||
3b6b9fab | 166 | if (!map_addr(skb, dataoff, dptr, datalen, matchoff, matchlen, |
720ac708 PM |
167 | &addr, port)) |
168 | return NF_DROP; | |
169 | ||
170 | matchend = matchoff + matchlen; | |
171 | ||
172 | /* The maddr= parameter (RFC 2361) specifies where to send | |
173 | * the reply. */ | |
174 | if (ct_sip_parse_address_param(ct, *dptr, matchend, *datalen, | |
175 | "maddr=", &poff, &plen, | |
176 | &addr) > 0 && | |
177 | addr.ip == ct->tuplehash[dir].tuple.src.u3.ip && | |
178 | addr.ip != ct->tuplehash[!dir].tuple.dst.u3.ip) { | |
cffee385 HH |
179 | buflen = sprintf(buffer, "%pI4", |
180 | &ct->tuplehash[!dir].tuple.dst.u3.ip); | |
3b6b9fab PM |
181 | if (!mangle_packet(skb, dataoff, dptr, datalen, |
182 | poff, plen, buffer, buflen)) | |
720ac708 PM |
183 | return NF_DROP; |
184 | } | |
185 | ||
186 | /* The received= parameter (RFC 2361) contains the address | |
187 | * from which the server received the request. */ | |
188 | if (ct_sip_parse_address_param(ct, *dptr, matchend, *datalen, | |
189 | "received=", &poff, &plen, | |
190 | &addr) > 0 && | |
191 | addr.ip == ct->tuplehash[dir].tuple.dst.u3.ip && | |
192 | addr.ip != ct->tuplehash[!dir].tuple.src.u3.ip) { | |
cffee385 HH |
193 | buflen = sprintf(buffer, "%pI4", |
194 | &ct->tuplehash[!dir].tuple.src.u3.ip); | |
3b6b9fab PM |
195 | if (!mangle_packet(skb, dataoff, dptr, datalen, |
196 | poff, plen, buffer, buflen)) | |
720ac708 PM |
197 | return NF_DROP; |
198 | } | |
199 | ||
200 | /* The rport= parameter (RFC 3581) contains the port number | |
201 | * from which the server received the request. */ | |
202 | if (ct_sip_parse_numerical_param(ct, *dptr, matchend, *datalen, | |
203 | "rport=", &poff, &plen, | |
204 | &n) > 0 && | |
205 | htons(n) == ct->tuplehash[dir].tuple.dst.u.udp.port && | |
206 | htons(n) != ct->tuplehash[!dir].tuple.src.u.udp.port) { | |
207 | __be16 p = ct->tuplehash[!dir].tuple.src.u.udp.port; | |
208 | buflen = sprintf(buffer, "%u", ntohs(p)); | |
3b6b9fab PM |
209 | if (!mangle_packet(skb, dataoff, dptr, datalen, |
210 | poff, plen, buffer, buflen)) | |
720ac708 PM |
211 | return NF_DROP; |
212 | } | |
9fafcd7b PM |
213 | } |
214 | ||
720ac708 | 215 | next: |
c978cd3a | 216 | /* Translate Contact headers */ |
3b6b9fab | 217 | coff = 0; |
c978cd3a | 218 | in_header = 0; |
3b6b9fab | 219 | while (ct_sip_parse_header_uri(ct, *dptr, &coff, *datalen, |
c978cd3a PM |
220 | SIP_HDR_CONTACT, &in_header, |
221 | &matchoff, &matchlen, | |
222 | &addr, &port) > 0) { | |
3b6b9fab | 223 | if (!map_addr(skb, dataoff, dptr, datalen, matchoff, matchlen, |
c978cd3a PM |
224 | &addr, port)) |
225 | return NF_DROP; | |
226 | } | |
227 | ||
3b6b9fab PM |
228 | if (!map_sip_addr(skb, dataoff, dptr, datalen, SIP_HDR_FROM) || |
229 | !map_sip_addr(skb, dataoff, dptr, datalen, SIP_HDR_TO)) | |
9fafcd7b | 230 | return NF_DROP; |
48f8ac26 | 231 | |
9fafcd7b PM |
232 | return NF_ACCEPT; |
233 | } | |
234 | ||
48f8ac26 PM |
235 | static void ip_nat_sip_seq_adjust(struct sk_buff *skb, s16 off) |
236 | { | |
237 | enum ip_conntrack_info ctinfo; | |
238 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
239 | const struct tcphdr *th; | |
240 | ||
241 | if (nf_ct_protonum(ct) != IPPROTO_TCP || off == 0) | |
242 | return; | |
243 | ||
244 | th = (struct tcphdr *)(skb->data + ip_hdrlen(skb)); | |
245 | nf_nat_set_seq_adjust(ct, ctinfo, th->seq, off); | |
246 | } | |
247 | ||
0f32a40f PM |
248 | /* Handles expected signalling connections and media streams */ |
249 | static void ip_nat_sip_expected(struct nf_conn *ct, | |
250 | struct nf_conntrack_expect *exp) | |
251 | { | |
252 | struct nf_nat_range range; | |
253 | ||
254 | /* This must be a fresh one. */ | |
255 | BUG_ON(ct->status & IPS_NAT_DONE_MASK); | |
256 | ||
257 | /* For DST manip, map port here to where it's expected. */ | |
258 | range.flags = (IP_NAT_RANGE_MAP_IPS | IP_NAT_RANGE_PROTO_SPECIFIED); | |
259 | range.min = range.max = exp->saved_proto; | |
260 | range.min_ip = range.max_ip = exp->saved_ip; | |
261 | nf_nat_setup_info(ct, &range, IP_NAT_MANIP_DST); | |
262 | ||
263 | /* Change src to where master sends to, but only if the connection | |
264 | * actually came from the same source. */ | |
265 | if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip == | |
266 | ct->master->tuplehash[exp->dir].tuple.src.u3.ip) { | |
267 | range.flags = IP_NAT_RANGE_MAP_IPS; | |
268 | range.min_ip = range.max_ip | |
269 | = ct->master->tuplehash[!exp->dir].tuple.dst.u3.ip; | |
270 | nf_nat_setup_info(ct, &range, IP_NAT_MANIP_SRC); | |
271 | } | |
272 | } | |
273 | ||
3b6b9fab | 274 | static unsigned int ip_nat_sip_expect(struct sk_buff *skb, unsigned int dataoff, |
0f32a40f PM |
275 | const char **dptr, unsigned int *datalen, |
276 | struct nf_conntrack_expect *exp, | |
277 | unsigned int matchoff, | |
278 | unsigned int matchlen) | |
279 | { | |
280 | enum ip_conntrack_info ctinfo; | |
281 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
282 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); | |
283 | __be32 newip; | |
284 | u_int16_t port; | |
285 | char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")]; | |
286 | unsigned buflen; | |
287 | ||
288 | /* Connection will come from reply */ | |
289 | if (ct->tuplehash[dir].tuple.src.u3.ip == ct->tuplehash[!dir].tuple.dst.u3.ip) | |
290 | newip = exp->tuple.dst.u3.ip; | |
291 | else | |
292 | newip = ct->tuplehash[!dir].tuple.dst.u3.ip; | |
293 | ||
294 | /* If the signalling port matches the connection's source port in the | |
295 | * original direction, try to use the destination port in the opposite | |
296 | * direction. */ | |
297 | if (exp->tuple.dst.u.udp.port == | |
298 | ct->tuplehash[dir].tuple.src.u.udp.port) | |
299 | port = ntohs(ct->tuplehash[!dir].tuple.dst.u.udp.port); | |
300 | else | |
301 | port = ntohs(exp->tuple.dst.u.udp.port); | |
302 | ||
303 | exp->saved_ip = exp->tuple.dst.u3.ip; | |
304 | exp->tuple.dst.u3.ip = newip; | |
305 | exp->saved_proto.udp.port = exp->tuple.dst.u.udp.port; | |
306 | exp->dir = !dir; | |
307 | exp->expectfn = ip_nat_sip_expected; | |
308 | ||
309 | for (; port != 0; port++) { | |
5b92b61f PNA |
310 | int ret; |
311 | ||
0f32a40f | 312 | exp->tuple.dst.u.udp.port = htons(port); |
5b92b61f PNA |
313 | ret = nf_ct_expect_related(exp); |
314 | if (ret == 0) | |
315 | break; | |
316 | else if (ret != -EBUSY) { | |
317 | port = 0; | |
0f32a40f | 318 | break; |
5b92b61f | 319 | } |
0f32a40f PM |
320 | } |
321 | ||
322 | if (port == 0) | |
323 | return NF_DROP; | |
324 | ||
325 | if (exp->tuple.dst.u3.ip != exp->saved_ip || | |
326 | exp->tuple.dst.u.udp.port != exp->saved_proto.udp.port) { | |
cffee385 | 327 | buflen = sprintf(buffer, "%pI4:%u", &newip, port); |
3b6b9fab PM |
328 | if (!mangle_packet(skb, dataoff, dptr, datalen, |
329 | matchoff, matchlen, buffer, buflen)) | |
0f32a40f PM |
330 | goto err; |
331 | } | |
332 | return NF_ACCEPT; | |
333 | ||
334 | err: | |
335 | nf_ct_unexpect_related(exp); | |
336 | return NF_DROP; | |
337 | } | |
338 | ||
3b6b9fab | 339 | static int mangle_content_len(struct sk_buff *skb, unsigned int dataoff, |
3e9b4600 | 340 | const char **dptr, unsigned int *datalen) |
9fafcd7b | 341 | { |
212440a7 PM |
342 | enum ip_conntrack_info ctinfo; |
343 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
3e9b4600 PM |
344 | unsigned int matchoff, matchlen; |
345 | char buffer[sizeof("65536")]; | |
346 | int buflen, c_len; | |
9fafcd7b | 347 | |
3e9b4600 PM |
348 | /* Get actual SDP length */ |
349 | if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen, | |
350 | SDP_HDR_VERSION, SDP_HDR_UNSPEC, | |
351 | &matchoff, &matchlen) <= 0) | |
352 | return 0; | |
353 | c_len = *datalen - matchoff + strlen("v="); | |
354 | ||
355 | /* Now, update SDP length */ | |
ea45f12a PM |
356 | if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CONTENT_LENGTH, |
357 | &matchoff, &matchlen) <= 0) | |
9fafcd7b PM |
358 | return 0; |
359 | ||
3e9b4600 | 360 | buflen = sprintf(buffer, "%u", c_len); |
3b6b9fab | 361 | return mangle_packet(skb, dataoff, dptr, datalen, matchoff, matchlen, |
3e9b4600 | 362 | buffer, buflen); |
9fafcd7b PM |
363 | } |
364 | ||
3b6b9fab PM |
365 | static int mangle_sdp_packet(struct sk_buff *skb, unsigned int dataoff, |
366 | const char **dptr, unsigned int *datalen, | |
367 | unsigned int sdpoff, | |
c71529e4 HX |
368 | enum sdp_header_types type, |
369 | enum sdp_header_types term, | |
370 | char *buffer, int buflen) | |
9fafcd7b | 371 | { |
212440a7 PM |
372 | enum ip_conntrack_info ctinfo; |
373 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
3e9b4600 | 374 | unsigned int matchlen, matchoff; |
9fafcd7b | 375 | |
3b6b9fab | 376 | if (ct_sip_get_sdp_header(ct, *dptr, sdpoff, *datalen, type, term, |
3e9b4600 | 377 | &matchoff, &matchlen) <= 0) |
c71529e4 | 378 | return -ENOENT; |
3b6b9fab | 379 | return mangle_packet(skb, dataoff, dptr, datalen, matchoff, matchlen, |
c71529e4 | 380 | buffer, buflen) ? 0 : -EINVAL; |
9fafcd7b PM |
381 | } |
382 | ||
3b6b9fab PM |
383 | static unsigned int ip_nat_sdp_addr(struct sk_buff *skb, unsigned int dataoff, |
384 | const char **dptr, unsigned int *datalen, | |
385 | unsigned int sdpoff, | |
4ab9e64e PM |
386 | enum sdp_header_types type, |
387 | enum sdp_header_types term, | |
388 | const union nf_inet_addr *addr) | |
9fafcd7b PM |
389 | { |
390 | char buffer[sizeof("nnn.nnn.nnn.nnn")]; | |
4ab9e64e | 391 | unsigned int buflen; |
9fafcd7b | 392 | |
cffee385 | 393 | buflen = sprintf(buffer, "%pI4", &addr->ip); |
3b6b9fab | 394 | if (mangle_sdp_packet(skb, dataoff, dptr, datalen, sdpoff, type, term, |
c71529e4 | 395 | buffer, buflen)) |
9fafcd7b PM |
396 | return 0; |
397 | ||
3b6b9fab | 398 | return mangle_content_len(skb, dataoff, dptr, datalen); |
4ab9e64e PM |
399 | } |
400 | ||
3b6b9fab PM |
401 | static unsigned int ip_nat_sdp_port(struct sk_buff *skb, unsigned int dataoff, |
402 | const char **dptr, unsigned int *datalen, | |
4ab9e64e PM |
403 | unsigned int matchoff, |
404 | unsigned int matchlen, | |
405 | u_int16_t port) | |
406 | { | |
407 | char buffer[sizeof("nnnnn")]; | |
408 | unsigned int buflen; | |
409 | ||
410 | buflen = sprintf(buffer, "%u", port); | |
3b6b9fab | 411 | if (!mangle_packet(skb, dataoff, dptr, datalen, matchoff, matchlen, |
4ab9e64e | 412 | buffer, buflen)) |
9fafcd7b PM |
413 | return 0; |
414 | ||
3b6b9fab | 415 | return mangle_content_len(skb, dataoff, dptr, datalen); |
4ab9e64e PM |
416 | } |
417 | ||
3b6b9fab PM |
418 | static unsigned int ip_nat_sdp_session(struct sk_buff *skb, unsigned int dataoff, |
419 | const char **dptr, unsigned int *datalen, | |
420 | unsigned int sdpoff, | |
4ab9e64e PM |
421 | const union nf_inet_addr *addr) |
422 | { | |
423 | char buffer[sizeof("nnn.nnn.nnn.nnn")]; | |
424 | unsigned int buflen; | |
425 | ||
426 | /* Mangle session description owner and contact addresses */ | |
cffee385 | 427 | buflen = sprintf(buffer, "%pI4", &addr->ip); |
3b6b9fab | 428 | if (mangle_sdp_packet(skb, dataoff, dptr, datalen, sdpoff, |
4ab9e64e PM |
429 | SDP_HDR_OWNER_IP4, SDP_HDR_MEDIA, |
430 | buffer, buflen)) | |
431 | return 0; | |
432 | ||
3b6b9fab | 433 | switch (mangle_sdp_packet(skb, dataoff, dptr, datalen, sdpoff, |
c71529e4 HX |
434 | SDP_HDR_CONNECTION_IP4, SDP_HDR_MEDIA, |
435 | buffer, buflen)) { | |
436 | case 0: | |
437 | /* | |
438 | * RFC 2327: | |
439 | * | |
440 | * Session description | |
441 | * | |
442 | * c=* (connection information - not required if included in all media) | |
443 | */ | |
444 | case -ENOENT: | |
445 | break; | |
446 | default: | |
9fafcd7b | 447 | return 0; |
c71529e4 | 448 | } |
9fafcd7b | 449 | |
3b6b9fab | 450 | return mangle_content_len(skb, dataoff, dptr, datalen); |
9fafcd7b PM |
451 | } |
452 | ||
453 | /* So, this packet has hit the connection tracking matching code. | |
454 | Mangle it, and change the expectation to match the new version. */ | |
3b6b9fab PM |
455 | static unsigned int ip_nat_sdp_media(struct sk_buff *skb, unsigned int dataoff, |
456 | const char **dptr, unsigned int *datalen, | |
4ab9e64e PM |
457 | struct nf_conntrack_expect *rtp_exp, |
458 | struct nf_conntrack_expect *rtcp_exp, | |
459 | unsigned int mediaoff, | |
460 | unsigned int medialen, | |
461 | union nf_inet_addr *rtp_addr) | |
9fafcd7b | 462 | { |
212440a7 PM |
463 | enum ip_conntrack_info ctinfo; |
464 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
9fafcd7b | 465 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); |
9fafcd7b PM |
466 | u_int16_t port; |
467 | ||
9fafcd7b | 468 | /* Connection will come from reply */ |
f4a607bf JB |
469 | if (ct->tuplehash[dir].tuple.src.u3.ip == |
470 | ct->tuplehash[!dir].tuple.dst.u3.ip) | |
4ab9e64e | 471 | rtp_addr->ip = rtp_exp->tuple.dst.u3.ip; |
f4a607bf | 472 | else |
4ab9e64e | 473 | rtp_addr->ip = ct->tuplehash[!dir].tuple.dst.u3.ip; |
9fafcd7b | 474 | |
a9c1d359 | 475 | rtp_exp->saved_ip = rtp_exp->tuple.dst.u3.ip; |
4ab9e64e | 476 | rtp_exp->tuple.dst.u3.ip = rtp_addr->ip; |
a9c1d359 PM |
477 | rtp_exp->saved_proto.udp.port = rtp_exp->tuple.dst.u.udp.port; |
478 | rtp_exp->dir = !dir; | |
479 | rtp_exp->expectfn = ip_nat_sip_expected; | |
480 | ||
481 | rtcp_exp->saved_ip = rtcp_exp->tuple.dst.u3.ip; | |
4ab9e64e | 482 | rtcp_exp->tuple.dst.u3.ip = rtp_addr->ip; |
a9c1d359 PM |
483 | rtcp_exp->saved_proto.udp.port = rtcp_exp->tuple.dst.u.udp.port; |
484 | rtcp_exp->dir = !dir; | |
485 | rtcp_exp->expectfn = ip_nat_sip_expected; | |
486 | ||
487 | /* Try to get same pair of ports: if not, try to change them. */ | |
488 | for (port = ntohs(rtp_exp->tuple.dst.u.udp.port); | |
489 | port != 0; port += 2) { | |
5b92b61f PNA |
490 | int ret; |
491 | ||
a9c1d359 | 492 | rtp_exp->tuple.dst.u.udp.port = htons(port); |
5b92b61f PNA |
493 | ret = nf_ct_expect_related(rtp_exp); |
494 | if (ret == -EBUSY) | |
a9c1d359 | 495 | continue; |
5b92b61f PNA |
496 | else if (ret < 0) { |
497 | port = 0; | |
498 | break; | |
499 | } | |
a9c1d359 | 500 | rtcp_exp->tuple.dst.u.udp.port = htons(port + 1); |
5b92b61f PNA |
501 | ret = nf_ct_expect_related(rtcp_exp); |
502 | if (ret == 0) | |
9fafcd7b | 503 | break; |
5b92b61f PNA |
504 | else if (ret != -EBUSY) { |
505 | nf_ct_unexpect_related(rtp_exp); | |
506 | port = 0; | |
507 | break; | |
508 | } | |
9fafcd7b PM |
509 | } |
510 | ||
511 | if (port == 0) | |
4ab9e64e PM |
512 | goto err1; |
513 | ||
514 | /* Update media port. */ | |
515 | if (rtp_exp->tuple.dst.u.udp.port != rtp_exp->saved_proto.udp.port && | |
3b6b9fab PM |
516 | !ip_nat_sdp_port(skb, dataoff, dptr, datalen, |
517 | mediaoff, medialen, port)) | |
4ab9e64e | 518 | goto err2; |
9fafcd7b | 519 | |
9fafcd7b | 520 | return NF_ACCEPT; |
4ab9e64e PM |
521 | |
522 | err2: | |
523 | nf_ct_unexpect_related(rtp_exp); | |
524 | nf_ct_unexpect_related(rtcp_exp); | |
525 | err1: | |
526 | return NF_DROP; | |
9fafcd7b PM |
527 | } |
528 | ||
529 | static void __exit nf_nat_sip_fini(void) | |
530 | { | |
531 | rcu_assign_pointer(nf_nat_sip_hook, NULL); | |
48f8ac26 | 532 | rcu_assign_pointer(nf_nat_sip_seq_adjust_hook, NULL); |
0f32a40f | 533 | rcu_assign_pointer(nf_nat_sip_expect_hook, NULL); |
4ab9e64e | 534 | rcu_assign_pointer(nf_nat_sdp_addr_hook, NULL); |
c7f485ab | 535 | rcu_assign_pointer(nf_nat_sdp_port_hook, NULL); |
4ab9e64e PM |
536 | rcu_assign_pointer(nf_nat_sdp_session_hook, NULL); |
537 | rcu_assign_pointer(nf_nat_sdp_media_hook, NULL); | |
9fafcd7b PM |
538 | synchronize_rcu(); |
539 | } | |
540 | ||
541 | static int __init nf_nat_sip_init(void) | |
542 | { | |
d1332e0a | 543 | BUG_ON(nf_nat_sip_hook != NULL); |
48f8ac26 | 544 | BUG_ON(nf_nat_sip_seq_adjust_hook != NULL); |
0f32a40f | 545 | BUG_ON(nf_nat_sip_expect_hook != NULL); |
4ab9e64e | 546 | BUG_ON(nf_nat_sdp_addr_hook != NULL); |
c7f485ab | 547 | BUG_ON(nf_nat_sdp_port_hook != NULL); |
4ab9e64e PM |
548 | BUG_ON(nf_nat_sdp_session_hook != NULL); |
549 | BUG_ON(nf_nat_sdp_media_hook != NULL); | |
9fafcd7b | 550 | rcu_assign_pointer(nf_nat_sip_hook, ip_nat_sip); |
48f8ac26 | 551 | rcu_assign_pointer(nf_nat_sip_seq_adjust_hook, ip_nat_sip_seq_adjust); |
0f32a40f | 552 | rcu_assign_pointer(nf_nat_sip_expect_hook, ip_nat_sip_expect); |
4ab9e64e | 553 | rcu_assign_pointer(nf_nat_sdp_addr_hook, ip_nat_sdp_addr); |
c7f485ab | 554 | rcu_assign_pointer(nf_nat_sdp_port_hook, ip_nat_sdp_port); |
4ab9e64e PM |
555 | rcu_assign_pointer(nf_nat_sdp_session_hook, ip_nat_sdp_session); |
556 | rcu_assign_pointer(nf_nat_sdp_media_hook, ip_nat_sdp_media); | |
9fafcd7b PM |
557 | return 0; |
558 | } | |
559 | ||
560 | module_init(nf_nat_sip_init); | |
561 | module_exit(nf_nat_sip_fini); |