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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 | 5 | * (C) 2007 United Security Providers |
9a664821 | 6 | * (C) 2007, 2008, 2011, 2012 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> | |
9a664821 | 15 | #include <linux/inet.h> |
9fafcd7b | 16 | #include <linux/udp.h> |
48f8ac26 | 17 | #include <linux/tcp.h> |
9fafcd7b PM |
18 | |
19 | #include <net/netfilter/nf_nat.h> | |
20 | #include <net/netfilter/nf_nat_helper.h> | |
9fafcd7b PM |
21 | #include <net/netfilter/nf_conntrack_helper.h> |
22 | #include <net/netfilter/nf_conntrack_expect.h> | |
41d73ec0 | 23 | #include <net/netfilter/nf_conntrack_seqadj.h> |
9fafcd7b PM |
24 | #include <linux/netfilter/nf_conntrack_sip.h> |
25 | ||
26 | MODULE_LICENSE("GPL"); | |
27 | MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>"); | |
28 | MODULE_DESCRIPTION("SIP NAT helper"); | |
29 | MODULE_ALIAS("ip_nat_sip"); | |
30 | ||
9fafcd7b | 31 | |
051966c0 PM |
32 | static unsigned int mangle_packet(struct sk_buff *skb, unsigned int protoff, |
33 | 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) { | |
9a664821 PM |
44 | th = (struct tcphdr *)(skb->data + protoff); |
45 | baseoff = protoff + th->doff * 4; | |
48f8ac26 PM |
46 | matchoff += dataoff - baseoff; |
47 | ||
48 | if (!__nf_nat_mangle_tcp_packet(skb, ct, ctinfo, | |
051966c0 | 49 | protoff, matchoff, matchlen, |
48f8ac26 PM |
50 | buffer, buflen, false)) |
51 | return 0; | |
52 | } else { | |
9a664821 | 53 | baseoff = protoff + sizeof(struct udphdr); |
48f8ac26 PM |
54 | matchoff += dataoff - baseoff; |
55 | ||
56 | if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo, | |
051966c0 | 57 | protoff, matchoff, matchlen, |
48f8ac26 PM |
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 | ||
9a664821 PM |
68 | static int sip_sprintf_addr(const struct nf_conn *ct, char *buffer, |
69 | const union nf_inet_addr *addr, bool delim) | |
70 | { | |
71 | if (nf_ct_l3num(ct) == NFPROTO_IPV4) | |
72 | return sprintf(buffer, "%pI4", &addr->ip); | |
73 | else { | |
74 | if (delim) | |
75 | return sprintf(buffer, "[%pI6c]", &addr->ip6); | |
76 | else | |
77 | return sprintf(buffer, "%pI6c", &addr->ip6); | |
78 | } | |
79 | } | |
80 | ||
81 | static int sip_sprintf_addr_port(const struct nf_conn *ct, char *buffer, | |
82 | const union nf_inet_addr *addr, u16 port) | |
83 | { | |
84 | if (nf_ct_l3num(ct) == NFPROTO_IPV4) | |
85 | return sprintf(buffer, "%pI4:%u", &addr->ip, port); | |
86 | else | |
87 | return sprintf(buffer, "[%pI6c]:%u", &addr->ip6, port); | |
88 | } | |
89 | ||
051966c0 PM |
90 | static int map_addr(struct sk_buff *skb, unsigned int protoff, |
91 | unsigned int dataoff, | |
ac367740 PM |
92 | const char **dptr, unsigned int *datalen, |
93 | unsigned int matchoff, unsigned int matchlen, | |
624f8b7b | 94 | union nf_inet_addr *addr, __be16 port) |
9fafcd7b | 95 | { |
212440a7 | 96 | enum ip_conntrack_info ctinfo; |
624f8b7b | 97 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); |
9fafcd7b | 98 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); |
7266507d | 99 | struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct); |
9a664821 | 100 | char buffer[INET6_ADDRSTRLEN + sizeof("[]:nnnnn")]; |
624f8b7b | 101 | unsigned int buflen; |
9a664821 | 102 | union nf_inet_addr newaddr; |
624f8b7b PM |
103 | __be16 newport; |
104 | ||
9a664821 | 105 | if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3, addr) && |
624f8b7b | 106 | ct->tuplehash[dir].tuple.src.u.udp.port == port) { |
9a664821 | 107 | newaddr = ct->tuplehash[!dir].tuple.dst.u3; |
624f8b7b | 108 | newport = ct->tuplehash[!dir].tuple.dst.u.udp.port; |
9a664821 | 109 | } else if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3, addr) && |
624f8b7b | 110 | ct->tuplehash[dir].tuple.dst.u.udp.port == port) { |
9a664821 | 111 | newaddr = ct->tuplehash[!dir].tuple.src.u3; |
7266507d KC |
112 | newport = ct_sip_info->forced_dport ? : |
113 | ct->tuplehash[!dir].tuple.src.u.udp.port; | |
9fafcd7b PM |
114 | } else |
115 | return 1; | |
116 | ||
9a664821 | 117 | if (nf_inet_addr_cmp(&newaddr, addr) && newport == port) |
624f8b7b PM |
118 | return 1; |
119 | ||
9a664821 | 120 | buflen = sip_sprintf_addr_port(ct, buffer, &newaddr, ntohs(newport)); |
051966c0 PM |
121 | return mangle_packet(skb, protoff, dataoff, dptr, datalen, |
122 | matchoff, matchlen, buffer, buflen); | |
9fafcd7b PM |
123 | } |
124 | ||
051966c0 PM |
125 | static int map_sip_addr(struct sk_buff *skb, unsigned int protoff, |
126 | unsigned int dataoff, | |
ac367740 | 127 | const char **dptr, unsigned int *datalen, |
624f8b7b | 128 | enum sip_header_types type) |
ac367740 PM |
129 | { |
130 | enum ip_conntrack_info ctinfo; | |
131 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
132 | unsigned int matchlen, matchoff; | |
624f8b7b PM |
133 | union nf_inet_addr addr; |
134 | __be16 port; | |
ac367740 | 135 | |
624f8b7b PM |
136 | if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen, type, NULL, |
137 | &matchoff, &matchlen, &addr, &port) <= 0) | |
ac367740 | 138 | return 1; |
051966c0 PM |
139 | return map_addr(skb, protoff, dataoff, dptr, datalen, |
140 | matchoff, matchlen, &addr, port); | |
ac367740 PM |
141 | } |
142 | ||
9a664821 | 143 | static unsigned int nf_nat_sip(struct sk_buff *skb, unsigned int protoff, |
051966c0 | 144 | unsigned int dataoff, |
2a6cfb22 | 145 | const char **dptr, unsigned int *datalen) |
9fafcd7b | 146 | { |
212440a7 PM |
147 | enum ip_conntrack_info ctinfo; |
148 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
720ac708 | 149 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); |
7266507d | 150 | struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct); |
3b6b9fab | 151 | unsigned int coff, matchoff, matchlen; |
48f8ac26 | 152 | enum sip_header_types hdr; |
624f8b7b PM |
153 | union nf_inet_addr addr; |
154 | __be16 port; | |
c978cd3a | 155 | int request, in_header; |
9fafcd7b | 156 | |
9fafcd7b | 157 | /* Basic rules: requests and responses. */ |
18082746 | 158 | if (strncasecmp(*dptr, "SIP/2.0", strlen("SIP/2.0")) != 0) { |
ac367740 | 159 | if (ct_sip_parse_request(ct, *dptr, *datalen, |
624f8b7b PM |
160 | &matchoff, &matchlen, |
161 | &addr, &port) > 0 && | |
051966c0 | 162 | !map_addr(skb, protoff, dataoff, dptr, datalen, |
b20ab9cc PNA |
163 | matchoff, matchlen, &addr, port)) { |
164 | nf_ct_helper_log(skb, ct, "cannot mangle SIP message"); | |
9fafcd7b | 165 | return NF_DROP; |
b20ab9cc | 166 | } |
720ac708 PM |
167 | request = 1; |
168 | } else | |
169 | request = 0; | |
170 | ||
48f8ac26 PM |
171 | if (nf_ct_protonum(ct) == IPPROTO_TCP) |
172 | hdr = SIP_HDR_VIA_TCP; | |
173 | else | |
174 | hdr = SIP_HDR_VIA_UDP; | |
175 | ||
720ac708 PM |
176 | /* Translate topmost Via header and parameters */ |
177 | if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen, | |
48f8ac26 | 178 | hdr, NULL, &matchoff, &matchlen, |
720ac708 | 179 | &addr, &port) > 0) { |
f22eb25c | 180 | unsigned int olen, matchend, poff, plen, buflen, n; |
9a664821 | 181 | char buffer[INET6_ADDRSTRLEN + sizeof("[]:nnnnn")]; |
720ac708 PM |
182 | |
183 | /* We're only interested in headers related to this | |
184 | * connection */ | |
185 | if (request) { | |
9a664821 PM |
186 | if (!nf_inet_addr_cmp(&addr, |
187 | &ct->tuplehash[dir].tuple.src.u3) || | |
720ac708 PM |
188 | port != ct->tuplehash[dir].tuple.src.u.udp.port) |
189 | goto next; | |
190 | } else { | |
9a664821 PM |
191 | if (!nf_inet_addr_cmp(&addr, |
192 | &ct->tuplehash[dir].tuple.dst.u3) || | |
720ac708 PM |
193 | port != ct->tuplehash[dir].tuple.dst.u.udp.port) |
194 | goto next; | |
195 | } | |
196 | ||
f22eb25c | 197 | olen = *datalen; |
051966c0 | 198 | if (!map_addr(skb, protoff, dataoff, dptr, datalen, |
b20ab9cc PNA |
199 | matchoff, matchlen, &addr, port)) { |
200 | nf_ct_helper_log(skb, ct, "cannot mangle Via header"); | |
720ac708 | 201 | return NF_DROP; |
b20ab9cc | 202 | } |
720ac708 | 203 | |
f22eb25c | 204 | matchend = matchoff + matchlen + *datalen - olen; |
720ac708 PM |
205 | |
206 | /* The maddr= parameter (RFC 2361) specifies where to send | |
207 | * the reply. */ | |
208 | if (ct_sip_parse_address_param(ct, *dptr, matchend, *datalen, | |
209 | "maddr=", &poff, &plen, | |
02b69cbd | 210 | &addr, true) > 0 && |
9a664821 PM |
211 | nf_inet_addr_cmp(&addr, &ct->tuplehash[dir].tuple.src.u3) && |
212 | !nf_inet_addr_cmp(&addr, &ct->tuplehash[!dir].tuple.dst.u3)) { | |
213 | buflen = sip_sprintf_addr(ct, buffer, | |
214 | &ct->tuplehash[!dir].tuple.dst.u3, | |
215 | true); | |
051966c0 | 216 | if (!mangle_packet(skb, protoff, dataoff, dptr, datalen, |
b20ab9cc PNA |
217 | poff, plen, buffer, buflen)) { |
218 | nf_ct_helper_log(skb, ct, "cannot mangle maddr"); | |
720ac708 | 219 | return NF_DROP; |
b20ab9cc | 220 | } |
720ac708 PM |
221 | } |
222 | ||
223 | /* The received= parameter (RFC 2361) contains the address | |
224 | * from which the server received the request. */ | |
225 | if (ct_sip_parse_address_param(ct, *dptr, matchend, *datalen, | |
226 | "received=", &poff, &plen, | |
02b69cbd | 227 | &addr, false) > 0 && |
9a664821 PM |
228 | nf_inet_addr_cmp(&addr, &ct->tuplehash[dir].tuple.dst.u3) && |
229 | !nf_inet_addr_cmp(&addr, &ct->tuplehash[!dir].tuple.src.u3)) { | |
230 | buflen = sip_sprintf_addr(ct, buffer, | |
231 | &ct->tuplehash[!dir].tuple.src.u3, | |
232 | false); | |
051966c0 | 233 | if (!mangle_packet(skb, protoff, dataoff, dptr, datalen, |
5aed9387 | 234 | poff, plen, buffer, buflen)) { |
b20ab9cc | 235 | nf_ct_helper_log(skb, ct, "cannot mangle received"); |
720ac708 | 236 | return NF_DROP; |
5aed9387 | 237 | } |
720ac708 PM |
238 | } |
239 | ||
240 | /* The rport= parameter (RFC 3581) contains the port number | |
241 | * from which the server received the request. */ | |
242 | if (ct_sip_parse_numerical_param(ct, *dptr, matchend, *datalen, | |
243 | "rport=", &poff, &plen, | |
244 | &n) > 0 && | |
245 | htons(n) == ct->tuplehash[dir].tuple.dst.u.udp.port && | |
246 | htons(n) != ct->tuplehash[!dir].tuple.src.u.udp.port) { | |
247 | __be16 p = ct->tuplehash[!dir].tuple.src.u.udp.port; | |
248 | buflen = sprintf(buffer, "%u", ntohs(p)); | |
051966c0 | 249 | if (!mangle_packet(skb, protoff, dataoff, dptr, datalen, |
b20ab9cc PNA |
250 | poff, plen, buffer, buflen)) { |
251 | nf_ct_helper_log(skb, ct, "cannot mangle rport"); | |
720ac708 | 252 | return NF_DROP; |
b20ab9cc | 253 | } |
720ac708 | 254 | } |
9fafcd7b PM |
255 | } |
256 | ||
720ac708 | 257 | next: |
c978cd3a | 258 | /* Translate Contact headers */ |
3b6b9fab | 259 | coff = 0; |
c978cd3a | 260 | in_header = 0; |
3b6b9fab | 261 | while (ct_sip_parse_header_uri(ct, *dptr, &coff, *datalen, |
c978cd3a PM |
262 | SIP_HDR_CONTACT, &in_header, |
263 | &matchoff, &matchlen, | |
264 | &addr, &port) > 0) { | |
051966c0 PM |
265 | if (!map_addr(skb, protoff, dataoff, dptr, datalen, |
266 | matchoff, matchlen, | |
b20ab9cc PNA |
267 | &addr, port)) { |
268 | nf_ct_helper_log(skb, ct, "cannot mangle contact"); | |
c978cd3a | 269 | return NF_DROP; |
b20ab9cc | 270 | } |
c978cd3a PM |
271 | } |
272 | ||
051966c0 | 273 | if (!map_sip_addr(skb, protoff, dataoff, dptr, datalen, SIP_HDR_FROM) || |
b20ab9cc PNA |
274 | !map_sip_addr(skb, protoff, dataoff, dptr, datalen, SIP_HDR_TO)) { |
275 | nf_ct_helper_log(skb, ct, "cannot mangle SIP from/to"); | |
9fafcd7b | 276 | return NF_DROP; |
b20ab9cc | 277 | } |
48f8ac26 | 278 | |
7266507d KC |
279 | /* Mangle destination port for Cisco phones, then fix up checksums */ |
280 | if (dir == IP_CT_DIR_REPLY && ct_sip_info->forced_dport) { | |
281 | struct udphdr *uh; | |
282 | ||
b20ab9cc PNA |
283 | if (!skb_make_writable(skb, skb->len)) { |
284 | nf_ct_helper_log(skb, ct, "cannot mangle packet"); | |
7266507d | 285 | return NF_DROP; |
b20ab9cc | 286 | } |
7266507d KC |
287 | |
288 | uh = (void *)skb->data + protoff; | |
289 | uh->dest = ct_sip_info->forced_dport; | |
290 | ||
291 | if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo, protoff, | |
b20ab9cc PNA |
292 | 0, 0, NULL, 0)) { |
293 | nf_ct_helper_log(skb, ct, "cannot mangle packet"); | |
7266507d | 294 | return NF_DROP; |
b20ab9cc | 295 | } |
7266507d KC |
296 | } |
297 | ||
9fafcd7b PM |
298 | return NF_ACCEPT; |
299 | } | |
300 | ||
9a664821 PM |
301 | static void nf_nat_sip_seq_adjust(struct sk_buff *skb, unsigned int protoff, |
302 | s16 off) | |
48f8ac26 PM |
303 | { |
304 | enum ip_conntrack_info ctinfo; | |
305 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
306 | const struct tcphdr *th; | |
307 | ||
308 | if (nf_ct_protonum(ct) != IPPROTO_TCP || off == 0) | |
309 | return; | |
310 | ||
9a664821 | 311 | th = (struct tcphdr *)(skb->data + protoff); |
41d73ec0 | 312 | nf_ct_seqadj_set(ct, ctinfo, th->seq, off); |
48f8ac26 PM |
313 | } |
314 | ||
0f32a40f | 315 | /* Handles expected signalling connections and media streams */ |
9a664821 | 316 | static void nf_nat_sip_expected(struct nf_conn *ct, |
0f32a40f PM |
317 | struct nf_conntrack_expect *exp) |
318 | { | |
c7232c99 | 319 | struct nf_nat_range range; |
0f32a40f PM |
320 | |
321 | /* This must be a fresh one. */ | |
322 | BUG_ON(ct->status & IPS_NAT_DONE_MASK); | |
323 | ||
324 | /* For DST manip, map port here to where it's expected. */ | |
cbc9f2f4 | 325 | range.flags = (NF_NAT_RANGE_MAP_IPS | NF_NAT_RANGE_PROTO_SPECIFIED); |
c7232c99 PM |
326 | range.min_proto = range.max_proto = exp->saved_proto; |
327 | range.min_addr = range.max_addr = exp->saved_addr; | |
cbc9f2f4 | 328 | nf_nat_setup_info(ct, &range, NF_NAT_MANIP_DST); |
0f32a40f PM |
329 | |
330 | /* Change src to where master sends to, but only if the connection | |
331 | * actually came from the same source. */ | |
9a664821 PM |
332 | if (nf_inet_addr_cmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3, |
333 | &ct->master->tuplehash[exp->dir].tuple.src.u3)) { | |
cbc9f2f4 | 334 | range.flags = NF_NAT_RANGE_MAP_IPS; |
c7232c99 PM |
335 | range.min_addr = range.max_addr |
336 | = ct->master->tuplehash[!exp->dir].tuple.dst.u3; | |
cbc9f2f4 | 337 | nf_nat_setup_info(ct, &range, NF_NAT_MANIP_SRC); |
0f32a40f PM |
338 | } |
339 | } | |
340 | ||
9a664821 | 341 | static unsigned int nf_nat_sip_expect(struct sk_buff *skb, unsigned int protoff, |
051966c0 | 342 | unsigned int dataoff, |
0f32a40f PM |
343 | const char **dptr, unsigned int *datalen, |
344 | struct nf_conntrack_expect *exp, | |
345 | unsigned int matchoff, | |
346 | unsigned int matchlen) | |
347 | { | |
348 | enum ip_conntrack_info ctinfo; | |
349 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
350 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); | |
7266507d | 351 | struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct); |
9a664821 | 352 | union nf_inet_addr newaddr; |
0f32a40f | 353 | u_int16_t port; |
7266507d | 354 | __be16 srcport; |
9a664821 | 355 | char buffer[INET6_ADDRSTRLEN + sizeof("[]:nnnnn")]; |
95c96174 | 356 | unsigned int buflen; |
0f32a40f PM |
357 | |
358 | /* Connection will come from reply */ | |
9a664821 PM |
359 | if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3, |
360 | &ct->tuplehash[!dir].tuple.dst.u3)) | |
361 | newaddr = exp->tuple.dst.u3; | |
0f32a40f | 362 | else |
9a664821 | 363 | newaddr = ct->tuplehash[!dir].tuple.dst.u3; |
0f32a40f PM |
364 | |
365 | /* If the signalling port matches the connection's source port in the | |
366 | * original direction, try to use the destination port in the opposite | |
367 | * direction. */ | |
7266507d KC |
368 | srcport = ct_sip_info->forced_dport ? : |
369 | ct->tuplehash[dir].tuple.src.u.udp.port; | |
370 | if (exp->tuple.dst.u.udp.port == srcport) | |
0f32a40f PM |
371 | port = ntohs(ct->tuplehash[!dir].tuple.dst.u.udp.port); |
372 | else | |
373 | port = ntohs(exp->tuple.dst.u.udp.port); | |
374 | ||
c7232c99 | 375 | exp->saved_addr = exp->tuple.dst.u3; |
9a664821 | 376 | exp->tuple.dst.u3 = newaddr; |
0f32a40f PM |
377 | exp->saved_proto.udp.port = exp->tuple.dst.u.udp.port; |
378 | exp->dir = !dir; | |
9a664821 | 379 | exp->expectfn = nf_nat_sip_expected; |
0f32a40f PM |
380 | |
381 | for (; port != 0; port++) { | |
5b92b61f PNA |
382 | int ret; |
383 | ||
0f32a40f | 384 | exp->tuple.dst.u.udp.port = htons(port); |
5b92b61f PNA |
385 | ret = nf_ct_expect_related(exp); |
386 | if (ret == 0) | |
387 | break; | |
388 | else if (ret != -EBUSY) { | |
389 | port = 0; | |
0f32a40f | 390 | break; |
5b92b61f | 391 | } |
0f32a40f PM |
392 | } |
393 | ||
b20ab9cc PNA |
394 | if (port == 0) { |
395 | nf_ct_helper_log(skb, ct, "all ports in use for SIP"); | |
0f32a40f | 396 | return NF_DROP; |
b20ab9cc | 397 | } |
0f32a40f | 398 | |
9a664821 | 399 | if (!nf_inet_addr_cmp(&exp->tuple.dst.u3, &exp->saved_addr) || |
0f32a40f | 400 | exp->tuple.dst.u.udp.port != exp->saved_proto.udp.port) { |
9a664821 | 401 | buflen = sip_sprintf_addr_port(ct, buffer, &newaddr, port); |
051966c0 | 402 | if (!mangle_packet(skb, protoff, dataoff, dptr, datalen, |
b20ab9cc PNA |
403 | matchoff, matchlen, buffer, buflen)) { |
404 | nf_ct_helper_log(skb, ct, "cannot mangle packet"); | |
0f32a40f | 405 | goto err; |
b20ab9cc | 406 | } |
0f32a40f PM |
407 | } |
408 | return NF_ACCEPT; | |
409 | ||
410 | err: | |
411 | nf_ct_unexpect_related(exp); | |
412 | return NF_DROP; | |
413 | } | |
414 | ||
051966c0 PM |
415 | static int mangle_content_len(struct sk_buff *skb, unsigned int protoff, |
416 | unsigned int dataoff, | |
3e9b4600 | 417 | const char **dptr, unsigned int *datalen) |
9fafcd7b | 418 | { |
212440a7 PM |
419 | enum ip_conntrack_info ctinfo; |
420 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
3e9b4600 PM |
421 | unsigned int matchoff, matchlen; |
422 | char buffer[sizeof("65536")]; | |
423 | int buflen, c_len; | |
9fafcd7b | 424 | |
3e9b4600 PM |
425 | /* Get actual SDP length */ |
426 | if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen, | |
427 | SDP_HDR_VERSION, SDP_HDR_UNSPEC, | |
428 | &matchoff, &matchlen) <= 0) | |
429 | return 0; | |
430 | c_len = *datalen - matchoff + strlen("v="); | |
431 | ||
432 | /* Now, update SDP length */ | |
ea45f12a PM |
433 | if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CONTENT_LENGTH, |
434 | &matchoff, &matchlen) <= 0) | |
9fafcd7b PM |
435 | return 0; |
436 | ||
3e9b4600 | 437 | buflen = sprintf(buffer, "%u", c_len); |
051966c0 PM |
438 | return mangle_packet(skb, protoff, dataoff, dptr, datalen, |
439 | matchoff, matchlen, buffer, buflen); | |
9fafcd7b PM |
440 | } |
441 | ||
051966c0 PM |
442 | static int mangle_sdp_packet(struct sk_buff *skb, unsigned int protoff, |
443 | unsigned int dataoff, | |
3b6b9fab PM |
444 | const char **dptr, unsigned int *datalen, |
445 | unsigned int sdpoff, | |
c71529e4 HX |
446 | enum sdp_header_types type, |
447 | enum sdp_header_types term, | |
448 | char *buffer, int buflen) | |
9fafcd7b | 449 | { |
212440a7 PM |
450 | enum ip_conntrack_info ctinfo; |
451 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
3e9b4600 | 452 | unsigned int matchlen, matchoff; |
9fafcd7b | 453 | |
3b6b9fab | 454 | if (ct_sip_get_sdp_header(ct, *dptr, sdpoff, *datalen, type, term, |
3e9b4600 | 455 | &matchoff, &matchlen) <= 0) |
c71529e4 | 456 | return -ENOENT; |
051966c0 PM |
457 | return mangle_packet(skb, protoff, dataoff, dptr, datalen, |
458 | matchoff, matchlen, buffer, buflen) ? 0 : -EINVAL; | |
9fafcd7b PM |
459 | } |
460 | ||
9a664821 | 461 | static unsigned int nf_nat_sdp_addr(struct sk_buff *skb, unsigned int protoff, |
051966c0 | 462 | unsigned int dataoff, |
3b6b9fab PM |
463 | const char **dptr, unsigned int *datalen, |
464 | unsigned int sdpoff, | |
4ab9e64e PM |
465 | enum sdp_header_types type, |
466 | enum sdp_header_types term, | |
467 | const union nf_inet_addr *addr) | |
9fafcd7b | 468 | { |
9a664821 PM |
469 | enum ip_conntrack_info ctinfo; |
470 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
471 | char buffer[INET6_ADDRSTRLEN]; | |
4ab9e64e | 472 | unsigned int buflen; |
9fafcd7b | 473 | |
9a664821 | 474 | buflen = sip_sprintf_addr(ct, buffer, addr, false); |
051966c0 PM |
475 | if (mangle_sdp_packet(skb, protoff, dataoff, dptr, datalen, |
476 | sdpoff, type, term, buffer, buflen)) | |
9fafcd7b PM |
477 | return 0; |
478 | ||
051966c0 | 479 | return mangle_content_len(skb, protoff, dataoff, dptr, datalen); |
4ab9e64e PM |
480 | } |
481 | ||
9a664821 | 482 | static unsigned int nf_nat_sdp_port(struct sk_buff *skb, unsigned int protoff, |
051966c0 | 483 | unsigned int dataoff, |
3b6b9fab | 484 | const char **dptr, unsigned int *datalen, |
4ab9e64e PM |
485 | unsigned int matchoff, |
486 | unsigned int matchlen, | |
487 | u_int16_t port) | |
488 | { | |
489 | char buffer[sizeof("nnnnn")]; | |
490 | unsigned int buflen; | |
491 | ||
492 | buflen = sprintf(buffer, "%u", port); | |
051966c0 PM |
493 | if (!mangle_packet(skb, protoff, dataoff, dptr, datalen, |
494 | matchoff, matchlen, buffer, buflen)) | |
9fafcd7b PM |
495 | return 0; |
496 | ||
051966c0 | 497 | return mangle_content_len(skb, protoff, dataoff, dptr, datalen); |
4ab9e64e PM |
498 | } |
499 | ||
9a664821 | 500 | static unsigned int nf_nat_sdp_session(struct sk_buff *skb, unsigned int protoff, |
051966c0 | 501 | unsigned int dataoff, |
3b6b9fab PM |
502 | const char **dptr, unsigned int *datalen, |
503 | unsigned int sdpoff, | |
4ab9e64e PM |
504 | const union nf_inet_addr *addr) |
505 | { | |
9a664821 PM |
506 | enum ip_conntrack_info ctinfo; |
507 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
508 | char buffer[INET6_ADDRSTRLEN]; | |
4ab9e64e PM |
509 | unsigned int buflen; |
510 | ||
511 | /* Mangle session description owner and contact addresses */ | |
9a664821 | 512 | buflen = sip_sprintf_addr(ct, buffer, addr, false); |
051966c0 | 513 | if (mangle_sdp_packet(skb, protoff, dataoff, dptr, datalen, sdpoff, |
9a664821 | 514 | SDP_HDR_OWNER, SDP_HDR_MEDIA, buffer, buflen)) |
4ab9e64e PM |
515 | return 0; |
516 | ||
051966c0 | 517 | switch (mangle_sdp_packet(skb, protoff, dataoff, dptr, datalen, sdpoff, |
9a664821 | 518 | SDP_HDR_CONNECTION, SDP_HDR_MEDIA, |
c71529e4 HX |
519 | buffer, buflen)) { |
520 | case 0: | |
521 | /* | |
522 | * RFC 2327: | |
523 | * | |
524 | * Session description | |
525 | * | |
526 | * c=* (connection information - not required if included in all media) | |
527 | */ | |
528 | case -ENOENT: | |
529 | break; | |
530 | default: | |
9fafcd7b | 531 | return 0; |
c71529e4 | 532 | } |
9fafcd7b | 533 | |
051966c0 | 534 | return mangle_content_len(skb, protoff, dataoff, dptr, datalen); |
9fafcd7b PM |
535 | } |
536 | ||
537 | /* So, this packet has hit the connection tracking matching code. | |
538 | Mangle it, and change the expectation to match the new version. */ | |
9a664821 | 539 | static unsigned int nf_nat_sdp_media(struct sk_buff *skb, unsigned int protoff, |
051966c0 | 540 | unsigned int dataoff, |
3b6b9fab | 541 | const char **dptr, unsigned int *datalen, |
4ab9e64e PM |
542 | struct nf_conntrack_expect *rtp_exp, |
543 | struct nf_conntrack_expect *rtcp_exp, | |
544 | unsigned int mediaoff, | |
545 | unsigned int medialen, | |
546 | union nf_inet_addr *rtp_addr) | |
9fafcd7b | 547 | { |
212440a7 PM |
548 | enum ip_conntrack_info ctinfo; |
549 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); | |
9fafcd7b | 550 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); |
9fafcd7b PM |
551 | u_int16_t port; |
552 | ||
9fafcd7b | 553 | /* Connection will come from reply */ |
9a664821 PM |
554 | if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3, |
555 | &ct->tuplehash[!dir].tuple.dst.u3)) | |
556 | *rtp_addr = rtp_exp->tuple.dst.u3; | |
f4a607bf | 557 | else |
9a664821 | 558 | *rtp_addr = ct->tuplehash[!dir].tuple.dst.u3; |
9fafcd7b | 559 | |
c7232c99 | 560 | rtp_exp->saved_addr = rtp_exp->tuple.dst.u3; |
9a664821 | 561 | rtp_exp->tuple.dst.u3 = *rtp_addr; |
a9c1d359 PM |
562 | rtp_exp->saved_proto.udp.port = rtp_exp->tuple.dst.u.udp.port; |
563 | rtp_exp->dir = !dir; | |
9a664821 | 564 | rtp_exp->expectfn = nf_nat_sip_expected; |
a9c1d359 | 565 | |
c7232c99 | 566 | rtcp_exp->saved_addr = rtcp_exp->tuple.dst.u3; |
9a664821 | 567 | rtcp_exp->tuple.dst.u3 = *rtp_addr; |
a9c1d359 PM |
568 | rtcp_exp->saved_proto.udp.port = rtcp_exp->tuple.dst.u.udp.port; |
569 | rtcp_exp->dir = !dir; | |
9a664821 | 570 | rtcp_exp->expectfn = nf_nat_sip_expected; |
a9c1d359 PM |
571 | |
572 | /* Try to get same pair of ports: if not, try to change them. */ | |
573 | for (port = ntohs(rtp_exp->tuple.dst.u.udp.port); | |
574 | port != 0; port += 2) { | |
5b92b61f PNA |
575 | int ret; |
576 | ||
a9c1d359 | 577 | rtp_exp->tuple.dst.u.udp.port = htons(port); |
5b92b61f PNA |
578 | ret = nf_ct_expect_related(rtp_exp); |
579 | if (ret == -EBUSY) | |
a9c1d359 | 580 | continue; |
5b92b61f PNA |
581 | else if (ret < 0) { |
582 | port = 0; | |
583 | break; | |
584 | } | |
a9c1d359 | 585 | rtcp_exp->tuple.dst.u.udp.port = htons(port + 1); |
5b92b61f PNA |
586 | ret = nf_ct_expect_related(rtcp_exp); |
587 | if (ret == 0) | |
9fafcd7b | 588 | break; |
3f509c68 PNA |
589 | else if (ret == -EBUSY) { |
590 | nf_ct_unexpect_related(rtp_exp); | |
591 | continue; | |
592 | } else if (ret < 0) { | |
5b92b61f PNA |
593 | nf_ct_unexpect_related(rtp_exp); |
594 | port = 0; | |
595 | break; | |
596 | } | |
9fafcd7b PM |
597 | } |
598 | ||
b20ab9cc PNA |
599 | if (port == 0) { |
600 | nf_ct_helper_log(skb, ct, "all ports in use for SDP media"); | |
4ab9e64e | 601 | goto err1; |
b20ab9cc | 602 | } |
4ab9e64e PM |
603 | |
604 | /* Update media port. */ | |
605 | if (rtp_exp->tuple.dst.u.udp.port != rtp_exp->saved_proto.udp.port && | |
9a664821 | 606 | !nf_nat_sdp_port(skb, protoff, dataoff, dptr, datalen, |
b20ab9cc PNA |
607 | mediaoff, medialen, port)) { |
608 | nf_ct_helper_log(skb, ct, "cannot mangle SDP message"); | |
4ab9e64e | 609 | goto err2; |
b20ab9cc | 610 | } |
9fafcd7b | 611 | |
9fafcd7b | 612 | return NF_ACCEPT; |
4ab9e64e PM |
613 | |
614 | err2: | |
615 | nf_ct_unexpect_related(rtp_exp); | |
616 | nf_ct_unexpect_related(rtcp_exp); | |
617 | err1: | |
618 | return NF_DROP; | |
9fafcd7b PM |
619 | } |
620 | ||
544d5c7d | 621 | static struct nf_ct_helper_expectfn sip_nat = { |
9a664821 PM |
622 | .name = "sip", |
623 | .expectfn = nf_nat_sip_expected, | |
544d5c7d PNA |
624 | }; |
625 | ||
9fafcd7b PM |
626 | static void __exit nf_nat_sip_fini(void) |
627 | { | |
180cf72f | 628 | RCU_INIT_POINTER(nf_nat_sip_hooks, NULL); |
629 | ||
544d5c7d | 630 | nf_ct_helper_expectfn_unregister(&sip_nat); |
9fafcd7b PM |
631 | synchronize_rcu(); |
632 | } | |
633 | ||
180cf72f | 634 | static const struct nf_nat_sip_hooks sip_hooks = { |
635 | .msg = nf_nat_sip, | |
636 | .seq_adjust = nf_nat_sip_seq_adjust, | |
637 | .expect = nf_nat_sip_expect, | |
638 | .sdp_addr = nf_nat_sdp_addr, | |
639 | .sdp_port = nf_nat_sdp_port, | |
640 | .sdp_session = nf_nat_sdp_session, | |
641 | .sdp_media = nf_nat_sdp_media, | |
642 | }; | |
643 | ||
9fafcd7b PM |
644 | static int __init nf_nat_sip_init(void) |
645 | { | |
180cf72f | 646 | BUG_ON(nf_nat_sip_hooks != NULL); |
647 | RCU_INIT_POINTER(nf_nat_sip_hooks, &sip_hooks); | |
544d5c7d | 648 | nf_ct_helper_expectfn_register(&sip_nat); |
9fafcd7b PM |
649 | return 0; |
650 | } | |
651 | ||
652 | module_init(nf_nat_sip_init); | |
653 | module_exit(nf_nat_sip_fini); |