2 * H.323 extension for NAT alteration.
4 * Copyright (c) 2006 Jing Min Zhao <zhaojingmin@users.sourceforge.net>
6 * This source code is licensed under General Public License version 2.
8 * Based on the 'brute force' H.323 NAT module by
9 * Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
12 #include <linux/module.h>
13 #include <linux/netfilter_ipv4.h>
14 #include <linux/netfilter.h>
16 #include <linux/tcp.h>
17 #include <linux/moduleparam.h>
19 #include <linux/netfilter_ipv4/ip_nat.h>
20 #include <linux/netfilter_ipv4/ip_nat_helper.h>
21 #include <linux/netfilter_ipv4/ip_nat_rule.h>
22 #include <linux/netfilter_ipv4/ip_conntrack_tuple.h>
23 #include <linux/netfilter_ipv4/ip_conntrack_h323.h>
24 #include <linux/netfilter_ipv4/ip_conntrack_helper.h>
29 #define DEBUGP(format, args...)
32 /****************************************************************************/
33 static int set_addr(struct sk_buff **pskb,
34 unsigned char **data, int dataoff,
35 unsigned int addroff, u_int32_t ip, u_int16_t port)
37 enum ip_conntrack_info ctinfo;
38 struct ip_conntrack *ct = ip_conntrack_get(*pskb, &ctinfo);
42 } __attribute__ ((__packed__)) buf;
43 struct tcphdr _tcph, *th;
46 buf.port = htons(port);
49 if ((*pskb)->nh.iph->protocol == IPPROTO_TCP) {
50 if (!ip_nat_mangle_tcp_packet(pskb, ct, ctinfo,
52 (char *) &buf, sizeof(buf))) {
54 printk("ip_nat_h323: ip_nat_mangle_tcp_packet"
59 /* Relocate data pointer */
60 th = skb_header_pointer(*pskb, (*pskb)->nh.iph->ihl * 4,
61 sizeof(_tcph), &_tcph);
64 *data = (*pskb)->data + (*pskb)->nh.iph->ihl * 4 +
65 th->doff * 4 + dataoff;
67 if (!ip_nat_mangle_udp_packet(pskb, ct, ctinfo,
69 (char *) &buf, sizeof(buf))) {
71 printk("ip_nat_h323: ip_nat_mangle_udp_packet"
75 /* ip_nat_mangle_udp_packet uses skb_make_writable() to copy
76 * or pull everything in a linear buffer, so we can safely
77 * use the skb pointers now */
78 *data = (*pskb)->data + (*pskb)->nh.iph->ihl * 4 +
79 sizeof(struct udphdr);
85 /****************************************************************************/
86 static int set_h225_addr(struct sk_buff **pskb,
87 unsigned char **data, int dataoff,
88 TransportAddress * addr,
89 u_int32_t ip, u_int16_t port)
91 return set_addr(pskb, data, dataoff, addr->ipAddress.ip, ip, port);
94 /****************************************************************************/
95 static int set_h245_addr(struct sk_buff **pskb,
96 unsigned char **data, int dataoff,
97 H245_TransportAddress * addr,
98 u_int32_t ip, u_int16_t port)
100 return set_addr(pskb, data, dataoff,
101 addr->unicastAddress.iPAddress.network, ip, port);
104 /****************************************************************************/
105 static int set_sig_addr(struct sk_buff **pskb, struct ip_conntrack *ct,
106 enum ip_conntrack_info ctinfo,
107 unsigned char **data,
108 TransportAddress * addr, int count)
110 struct ip_ct_h323_master *info = &ct->help.ct_h323_info;
111 int dir = CTINFO2DIR(ctinfo);
116 for (i = 0; i < count; i++) {
117 if (get_h225_addr(*data, &addr[i], &ip, &port)) {
118 if (ip == ct->tuplehash[dir].tuple.src.ip &&
119 port == info->sig_port[dir]) {
122 /* Fix for Gnomemeeting */
124 get_h225_addr(*data, &addr[0],
126 (ntohl(ip) & 0xff000000) == 0x7f000000)
130 ("ip_nat_ras: set signal address "
131 "%u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
133 NIPQUAD(ct->tuplehash[!dir].tuple.dst.
134 ip), info->sig_port[!dir]);
135 return set_h225_addr(pskb, data, 0, &addr[i],
138 info->sig_port[!dir]);
139 } else if (ip == ct->tuplehash[dir].tuple.dst.ip &&
140 port == info->sig_port[dir]) {
143 ("ip_nat_ras: set signal address "
144 "%u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
146 NIPQUAD(ct->tuplehash[!dir].tuple.src.
147 ip), info->sig_port[!dir]);
148 return set_h225_addr(pskb, data, 0, &addr[i],
151 info->sig_port[!dir]);
159 /****************************************************************************/
160 static int set_ras_addr(struct sk_buff **pskb, struct ip_conntrack *ct,
161 enum ip_conntrack_info ctinfo,
162 unsigned char **data,
163 TransportAddress * addr, int count)
165 int dir = CTINFO2DIR(ctinfo);
170 for (i = 0; i < count; i++) {
171 if (get_h225_addr(*data, &addr[i], &ip, &port) &&
172 ip == ct->tuplehash[dir].tuple.src.ip &&
173 port == ntohs(ct->tuplehash[dir].tuple.src.u.udp.port)) {
174 DEBUGP("ip_nat_ras: set rasAddress "
175 "%u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
177 NIPQUAD(ct->tuplehash[!dir].tuple.dst.ip),
178 ntohs(ct->tuplehash[!dir].tuple.dst.u.udp.
180 return set_h225_addr(pskb, data, 0, &addr[i],
181 ct->tuplehash[!dir].tuple.dst.ip,
182 ntohs(ct->tuplehash[!dir].tuple.
190 /****************************************************************************/
191 static int nat_rtp_rtcp(struct sk_buff **pskb, struct ip_conntrack *ct,
192 enum ip_conntrack_info ctinfo,
193 unsigned char **data, int dataoff,
194 H245_TransportAddress * addr,
195 u_int16_t port, u_int16_t rtp_port,
196 struct ip_conntrack_expect *rtp_exp,
197 struct ip_conntrack_expect *rtcp_exp)
199 struct ip_ct_h323_master *info = &ct->help.ct_h323_info;
200 int dir = CTINFO2DIR(ctinfo);
202 u_int16_t nated_port;
204 /* Set expectations for NAT */
205 rtp_exp->saved_proto.udp.port = rtp_exp->tuple.dst.u.udp.port;
206 rtp_exp->expectfn = ip_nat_follow_master;
208 rtcp_exp->saved_proto.udp.port = rtcp_exp->tuple.dst.u.udp.port;
209 rtcp_exp->expectfn = ip_nat_follow_master;
210 rtcp_exp->dir = !dir;
212 /* Lookup existing expects */
213 for (i = 0; i < H323_RTP_CHANNEL_MAX; i++) {
214 if (info->rtp_port[i][dir] == rtp_port) {
217 /* Use allocated ports first. This will refresh
219 rtp_exp->tuple.dst.u.udp.port =
220 htons(info->rtp_port[i][dir]);
221 rtcp_exp->tuple.dst.u.udp.port =
222 htons(info->rtp_port[i][dir] + 1);
224 } else if (info->rtp_port[i][dir] == 0) {
230 /* Run out of expectations */
231 if (i >= H323_RTP_CHANNEL_MAX) {
233 printk("ip_nat_h323: out of expectations\n");
237 /* Try to get a pair of ports. */
238 for (nated_port = ntohs(rtp_exp->tuple.dst.u.udp.port);
239 nated_port != 0; nated_port += 2) {
240 rtp_exp->tuple.dst.u.udp.port = htons(nated_port);
241 if (ip_conntrack_expect_related(rtp_exp) == 0) {
242 rtcp_exp->tuple.dst.u.udp.port =
243 htons(nated_port + 1);
244 if (ip_conntrack_expect_related(rtcp_exp) == 0)
246 ip_conntrack_unexpect_related(rtp_exp);
250 if (nated_port == 0) { /* No port available */
252 printk("ip_nat_h323: out of RTP ports\n");
257 if (set_h245_addr(pskb, data, dataoff, addr,
258 ct->tuplehash[!dir].tuple.dst.ip,
259 (port & 1) ? nated_port + 1 : nated_port) == 0) {
261 info->rtp_port[i][dir] = rtp_port;
262 info->rtp_port[i][!dir] = nated_port;
264 ip_conntrack_unexpect_related(rtp_exp);
265 ip_conntrack_unexpect_related(rtcp_exp);
270 DEBUGP("ip_nat_h323: expect RTP %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
271 NIPQUAD(rtp_exp->tuple.src.ip),
272 ntohs(rtp_exp->tuple.src.u.udp.port),
273 NIPQUAD(rtp_exp->tuple.dst.ip),
274 ntohs(rtp_exp->tuple.dst.u.udp.port));
275 DEBUGP("ip_nat_h323: expect RTCP %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
276 NIPQUAD(rtcp_exp->tuple.src.ip),
277 ntohs(rtcp_exp->tuple.src.u.udp.port),
278 NIPQUAD(rtcp_exp->tuple.dst.ip),
279 ntohs(rtcp_exp->tuple.dst.u.udp.port));
284 /****************************************************************************/
285 static int nat_t120(struct sk_buff **pskb, struct ip_conntrack *ct,
286 enum ip_conntrack_info ctinfo,
287 unsigned char **data, int dataoff,
288 H245_TransportAddress * addr, u_int16_t port,
289 struct ip_conntrack_expect *exp)
291 int dir = CTINFO2DIR(ctinfo);
292 u_int16_t nated_port = port;
294 /* Set expectations for NAT */
295 exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
296 exp->expectfn = ip_nat_follow_master;
299 /* Try to get same port: if not, try to change it. */
300 for (; nated_port != 0; nated_port++) {
301 exp->tuple.dst.u.tcp.port = htons(nated_port);
302 if (ip_conntrack_expect_related(exp) == 0)
306 if (nated_port == 0) { /* No port available */
308 printk("ip_nat_h323: out of TCP ports\n");
313 if (set_h245_addr(pskb, data, dataoff, addr,
314 ct->tuplehash[!dir].tuple.dst.ip, nated_port) < 0) {
315 ip_conntrack_unexpect_related(exp);
319 DEBUGP("ip_nat_h323: expect T.120 %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
320 NIPQUAD(exp->tuple.src.ip), ntohs(exp->tuple.src.u.tcp.port),
321 NIPQUAD(exp->tuple.dst.ip), ntohs(exp->tuple.dst.u.tcp.port));
326 /****************************************************************************
327 * This conntrack expect function replaces ip_conntrack_h245_expect()
328 * which was set by ip_conntrack_helper_h323.c. It calls both
329 * ip_nat_follow_master() and ip_conntrack_h245_expect()
330 ****************************************************************************/
331 static void ip_nat_h245_expect(struct ip_conntrack *new,
332 struct ip_conntrack_expect *this)
334 ip_nat_follow_master(new, this);
335 ip_conntrack_h245_expect(new, this);
338 /****************************************************************************/
339 static int nat_h245(struct sk_buff **pskb, struct ip_conntrack *ct,
340 enum ip_conntrack_info ctinfo,
341 unsigned char **data, int dataoff,
342 TransportAddress * addr, u_int16_t port,
343 struct ip_conntrack_expect *exp)
345 struct ip_ct_h323_master *info = &ct->help.ct_h323_info;
346 int dir = CTINFO2DIR(ctinfo);
347 u_int16_t nated_port = port;
349 /* Set expectations for NAT */
350 exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
351 exp->expectfn = ip_nat_h245_expect;
354 /* Check existing expects */
355 if (info->sig_port[dir] == port)
356 nated_port = info->sig_port[!dir];
358 /* Try to get same port: if not, try to change it. */
359 for (; nated_port != 0; nated_port++) {
360 exp->tuple.dst.u.tcp.port = htons(nated_port);
361 if (ip_conntrack_expect_related(exp) == 0)
365 if (nated_port == 0) { /* No port available */
367 printk("ip_nat_q931: out of TCP ports\n");
372 if (set_h225_addr(pskb, data, dataoff, addr,
373 ct->tuplehash[!dir].tuple.dst.ip,
376 info->sig_port[dir] = port;
377 info->sig_port[!dir] = nated_port;
379 ip_conntrack_unexpect_related(exp);
383 DEBUGP("ip_nat_q931: expect H.245 %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
384 NIPQUAD(exp->tuple.src.ip), ntohs(exp->tuple.src.u.tcp.port),
385 NIPQUAD(exp->tuple.dst.ip), ntohs(exp->tuple.dst.u.tcp.port));
390 /****************************************************************************
391 * This conntrack expect function replaces ip_conntrack_q931_expect()
392 * which was set by ip_conntrack_helper_h323.c.
393 ****************************************************************************/
394 static void ip_nat_q931_expect(struct ip_conntrack *new,
395 struct ip_conntrack_expect *this)
397 struct ip_nat_range range;
399 if (this->tuple.src.ip != 0) { /* Only accept calls from GK */
400 ip_nat_follow_master(new, this);
404 /* This must be a fresh one. */
405 BUG_ON(new->status & IPS_NAT_DONE_MASK);
407 /* Change src to where master sends to */
408 range.flags = IP_NAT_RANGE_MAP_IPS;
409 range.min_ip = range.max_ip = new->tuplehash[!this->dir].tuple.src.ip;
411 /* hook doesn't matter, but it has to do source manip */
412 ip_nat_setup_info(new, &range, NF_IP_POST_ROUTING);
414 /* For DST manip, map port here to where it's expected. */
415 range.flags = (IP_NAT_RANGE_MAP_IPS | IP_NAT_RANGE_PROTO_SPECIFIED);
416 range.min = range.max = this->saved_proto;
417 range.min_ip = range.max_ip =
418 new->master->tuplehash[!this->dir].tuple.src.ip;
420 /* hook doesn't matter, but it has to do destination manip */
421 ip_nat_setup_info(new, &range, NF_IP_PRE_ROUTING);
424 ip_conntrack_q931_expect(new, this);
427 /****************************************************************************/
428 static int nat_q931(struct sk_buff **pskb, struct ip_conntrack *ct,
429 enum ip_conntrack_info ctinfo,
430 unsigned char **data, TransportAddress * addr, int idx,
431 u_int16_t port, struct ip_conntrack_expect *exp)
433 struct ip_ct_h323_master *info = &ct->help.ct_h323_info;
434 int dir = CTINFO2DIR(ctinfo);
435 u_int16_t nated_port = port;
438 /* Set expectations for NAT */
439 exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
440 exp->expectfn = ip_nat_q931_expect;
443 /* Check existing expects */
444 if (info->sig_port[dir] == port)
445 nated_port = info->sig_port[!dir];
447 /* Try to get same port: if not, try to change it. */
448 for (; nated_port != 0; nated_port++) {
449 exp->tuple.dst.u.tcp.port = htons(nated_port);
450 if (ip_conntrack_expect_related(exp) == 0)
454 if (nated_port == 0) { /* No port available */
456 printk("ip_nat_ras: out of TCP ports\n");
461 if (set_h225_addr(pskb, data, 0, &addr[idx],
462 ct->tuplehash[!dir].tuple.dst.ip,
465 info->sig_port[dir] = port;
466 info->sig_port[!dir] = nated_port;
468 /* Fix for Gnomemeeting */
470 get_h225_addr(*data, &addr[0], &ip, &port) &&
471 (ntohl(ip) & 0xff000000) == 0x7f000000) {
472 set_h225_addr_hook(pskb, data, 0, &addr[0],
473 ct->tuplehash[!dir].tuple.dst.ip,
474 info->sig_port[!dir]);
477 ip_conntrack_unexpect_related(exp);
482 DEBUGP("ip_nat_ras: expect Q.931 %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
483 NIPQUAD(exp->tuple.src.ip), ntohs(exp->tuple.src.u.tcp.port),
484 NIPQUAD(exp->tuple.dst.ip), ntohs(exp->tuple.dst.u.tcp.port));
489 /****************************************************************************/
490 static void ip_nat_callforwarding_expect(struct ip_conntrack *new,
491 struct ip_conntrack_expect *this)
493 struct ip_nat_range range;
495 /* This must be a fresh one. */
496 BUG_ON(new->status & IPS_NAT_DONE_MASK);
498 /* Change src to where master sends to */
499 range.flags = IP_NAT_RANGE_MAP_IPS;
500 range.min_ip = range.max_ip = new->tuplehash[!this->dir].tuple.src.ip;
502 /* hook doesn't matter, but it has to do source manip */
503 ip_nat_setup_info(new, &range, NF_IP_POST_ROUTING);
505 /* For DST manip, map port here to where it's expected. */
506 range.flags = (IP_NAT_RANGE_MAP_IPS | IP_NAT_RANGE_PROTO_SPECIFIED);
507 range.min = range.max = this->saved_proto;
508 range.min_ip = range.max_ip = this->saved_ip;
510 /* hook doesn't matter, but it has to do destination manip */
511 ip_nat_setup_info(new, &range, NF_IP_PRE_ROUTING);
513 ip_conntrack_q931_expect(new, this);
516 /****************************************************************************/
517 static int nat_callforwarding(struct sk_buff **pskb, struct ip_conntrack *ct,
518 enum ip_conntrack_info ctinfo,
519 unsigned char **data, int dataoff,
520 TransportAddress * addr, u_int16_t port,
521 struct ip_conntrack_expect *exp)
523 int dir = CTINFO2DIR(ctinfo);
524 u_int16_t nated_port;
526 /* Set expectations for NAT */
527 exp->saved_ip = exp->tuple.dst.ip;
528 exp->tuple.dst.ip = ct->tuplehash[!dir].tuple.dst.ip;
529 exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
530 exp->expectfn = ip_nat_callforwarding_expect;
533 /* Try to get same port: if not, try to change it. */
534 for (nated_port = port; nated_port != 0; nated_port++) {
535 exp->tuple.dst.u.tcp.port = htons(nated_port);
536 if (ip_conntrack_expect_related(exp) == 0)
540 if (nated_port == 0) { /* No port available */
542 printk("ip_nat_q931: out of TCP ports\n");
547 if (!set_h225_addr(pskb, data, dataoff, addr,
548 ct->tuplehash[!dir].tuple.dst.ip,
550 ip_conntrack_unexpect_related(exp);
555 DEBUGP("ip_nat_q931: expect Call Forwarding "
556 "%u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
557 NIPQUAD(exp->tuple.src.ip), ntohs(exp->tuple.src.u.tcp.port),
558 NIPQUAD(exp->tuple.dst.ip), ntohs(exp->tuple.dst.u.tcp.port));
563 /****************************************************************************/
564 static int __init init(void)
566 BUG_ON(set_h245_addr_hook != NULL);
567 BUG_ON(set_h225_addr_hook != NULL);
568 BUG_ON(set_sig_addr_hook != NULL);
569 BUG_ON(set_ras_addr_hook != NULL);
570 BUG_ON(nat_rtp_rtcp_hook != NULL);
571 BUG_ON(nat_t120_hook != NULL);
572 BUG_ON(nat_h245_hook != NULL);
573 BUG_ON(nat_callforwarding_hook != NULL);
574 BUG_ON(nat_q931_hook != NULL);
576 set_h245_addr_hook = set_h245_addr;
577 set_h225_addr_hook = set_h225_addr;
578 set_sig_addr_hook = set_sig_addr;
579 set_ras_addr_hook = set_ras_addr;
580 nat_rtp_rtcp_hook = nat_rtp_rtcp;
581 nat_t120_hook = nat_t120;
582 nat_h245_hook = nat_h245;
583 nat_callforwarding_hook = nat_callforwarding;
584 nat_q931_hook = nat_q931;
586 DEBUGP("ip_nat_h323: init success\n");
590 /****************************************************************************/
591 static void __exit fini(void)
593 set_h245_addr_hook = NULL;
594 set_h225_addr_hook = NULL;
595 set_sig_addr_hook = NULL;
596 set_ras_addr_hook = NULL;
597 nat_rtp_rtcp_hook = NULL;
598 nat_t120_hook = NULL;
599 nat_h245_hook = NULL;
600 nat_callforwarding_hook = NULL;
601 nat_q931_hook = NULL;
605 /****************************************************************************/
609 MODULE_AUTHOR("Jing Min Zhao <zhaojingmin@users.sourceforge.net>");
610 MODULE_DESCRIPTION("H.323 NAT helper");
611 MODULE_LICENSE("GPL");