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/moduleparam.h>
14 #include <linux/tcp.h>
17 #include <net/netfilter/nf_nat.h>
18 #include <net/netfilter/nf_nat_helper.h>
19 #include <net/netfilter/nf_nat_rule.h>
20 #include <net/netfilter/nf_conntrack_helper.h>
21 #include <net/netfilter/nf_conntrack_expect.h>
22 #include <linux/netfilter/nf_conntrack_h323.h>
24 /****************************************************************************/
25 static int set_addr(struct sk_buff *skb,
26 unsigned char **data, int dataoff,
27 unsigned int addroff, __be32 ip, __be16 port)
29 enum ip_conntrack_info ctinfo;
30 struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
34 } __attribute__ ((__packed__)) buf;
35 struct tcphdr _tcph, *th;
41 if (ip_hdr(skb)->protocol == IPPROTO_TCP) {
42 if (!nf_nat_mangle_tcp_packet(skb, ct, ctinfo,
44 (char *) &buf, sizeof(buf))) {
46 printk("nf_nat_h323: nf_nat_mangle_tcp_packet"
51 /* Relocate data pointer */
52 th = skb_header_pointer(skb, ip_hdrlen(skb),
53 sizeof(_tcph), &_tcph);
56 *data = skb->data + ip_hdrlen(skb) + th->doff * 4 + dataoff;
58 if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo,
60 (char *) &buf, sizeof(buf))) {
62 printk("nf_nat_h323: nf_nat_mangle_udp_packet"
66 /* nf_nat_mangle_udp_packet uses skb_make_writable() to copy
67 * or pull everything in a linear buffer, so we can safely
68 * use the skb pointers now */
69 *data = skb->data + ip_hdrlen(skb) + sizeof(struct udphdr);
75 /****************************************************************************/
76 static int set_h225_addr(struct sk_buff *skb,
77 unsigned char **data, int dataoff,
78 TransportAddress *taddr,
79 union nf_conntrack_address *addr, __be16 port)
81 return set_addr(skb, data, dataoff, taddr->ipAddress.ip,
85 /****************************************************************************/
86 static int set_h245_addr(struct sk_buff *skb,
87 unsigned char **data, int dataoff,
88 H245_TransportAddress *taddr,
89 union nf_conntrack_address *addr, __be16 port)
91 return set_addr(skb, data, dataoff,
92 taddr->unicastAddress.iPAddress.network,
96 /****************************************************************************/
97 static int set_sig_addr(struct sk_buff *skb, struct nf_conn *ct,
98 enum ip_conntrack_info ctinfo,
100 TransportAddress *taddr, int count)
102 struct nf_ct_h323_master *info = &nfct_help(ct)->help.ct_h323_info;
103 int dir = CTINFO2DIR(ctinfo);
106 union nf_conntrack_address addr;
108 for (i = 0; i < count; i++) {
109 if (get_h225_addr(ct, *data, &taddr[i], &addr, &port)) {
110 if (addr.ip == ct->tuplehash[dir].tuple.src.u3.ip &&
111 port == info->sig_port[dir]) {
114 /* Fix for Gnomemeeting */
116 get_h225_addr(ct, *data, &taddr[0],
118 (ntohl(addr.ip) & 0xff000000) == 0x7f000000)
121 pr_debug("nf_nat_ras: set signal address "
122 "%u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
123 NIPQUAD(addr.ip), port,
124 NIPQUAD(ct->tuplehash[!dir].tuple.dst.u3.ip),
125 info->sig_port[!dir]);
126 return set_h225_addr(skb, data, 0, &taddr[i],
127 &ct->tuplehash[!dir].
129 info->sig_port[!dir]);
130 } else if (addr.ip == ct->tuplehash[dir].tuple.dst.u3.ip &&
131 port == info->sig_port[dir]) {
133 pr_debug("nf_nat_ras: set signal address "
134 "%u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
135 NIPQUAD(addr.ip), port,
136 NIPQUAD(ct->tuplehash[!dir].tuple.src.u3.ip),
137 info->sig_port[!dir]);
138 return set_h225_addr(skb, data, 0, &taddr[i],
139 &ct->tuplehash[!dir].
141 info->sig_port[!dir]);
149 /****************************************************************************/
150 static int set_ras_addr(struct sk_buff *skb, struct nf_conn *ct,
151 enum ip_conntrack_info ctinfo,
152 unsigned char **data,
153 TransportAddress *taddr, int count)
155 int dir = CTINFO2DIR(ctinfo);
158 union nf_conntrack_address addr;
160 for (i = 0; i < count; i++) {
161 if (get_h225_addr(ct, *data, &taddr[i], &addr, &port) &&
162 addr.ip == ct->tuplehash[dir].tuple.src.u3.ip &&
163 port == ct->tuplehash[dir].tuple.src.u.udp.port) {
164 pr_debug("nf_nat_ras: set rasAddress "
165 "%u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
166 NIPQUAD(addr.ip), ntohs(port),
167 NIPQUAD(ct->tuplehash[!dir].tuple.dst.u3.ip),
168 ntohs(ct->tuplehash[!dir].tuple.dst.u.udp.port));
169 return set_h225_addr(skb, data, 0, &taddr[i],
170 &ct->tuplehash[!dir].tuple.dst.u3,
171 ct->tuplehash[!dir].tuple.
179 /****************************************************************************/
180 static int nat_rtp_rtcp(struct sk_buff *skb, struct nf_conn *ct,
181 enum ip_conntrack_info ctinfo,
182 unsigned char **data, int dataoff,
183 H245_TransportAddress *taddr,
184 __be16 port, __be16 rtp_port,
185 struct nf_conntrack_expect *rtp_exp,
186 struct nf_conntrack_expect *rtcp_exp)
188 struct nf_ct_h323_master *info = &nfct_help(ct)->help.ct_h323_info;
189 int dir = CTINFO2DIR(ctinfo);
191 u_int16_t nated_port;
193 /* Set expectations for NAT */
194 rtp_exp->saved_proto.udp.port = rtp_exp->tuple.dst.u.udp.port;
195 rtp_exp->expectfn = nf_nat_follow_master;
197 rtcp_exp->saved_proto.udp.port = rtcp_exp->tuple.dst.u.udp.port;
198 rtcp_exp->expectfn = nf_nat_follow_master;
199 rtcp_exp->dir = !dir;
201 /* Lookup existing expects */
202 for (i = 0; i < H323_RTP_CHANNEL_MAX; i++) {
203 if (info->rtp_port[i][dir] == rtp_port) {
206 /* Use allocated ports first. This will refresh
208 rtp_exp->tuple.dst.u.udp.port = info->rtp_port[i][dir];
209 rtcp_exp->tuple.dst.u.udp.port =
210 htons(ntohs(info->rtp_port[i][dir]) + 1);
212 } else if (info->rtp_port[i][dir] == 0) {
218 /* Run out of expectations */
219 if (i >= H323_RTP_CHANNEL_MAX) {
221 printk("nf_nat_h323: out of expectations\n");
225 /* Try to get a pair of ports. */
226 for (nated_port = ntohs(rtp_exp->tuple.dst.u.udp.port);
227 nated_port != 0; nated_port += 2) {
228 rtp_exp->tuple.dst.u.udp.port = htons(nated_port);
229 if (nf_ct_expect_related(rtp_exp) == 0) {
230 rtcp_exp->tuple.dst.u.udp.port =
231 htons(nated_port + 1);
232 if (nf_ct_expect_related(rtcp_exp) == 0)
234 nf_ct_unexpect_related(rtp_exp);
238 if (nated_port == 0) { /* No port available */
240 printk("nf_nat_h323: out of RTP ports\n");
245 if (set_h245_addr(skb, data, dataoff, taddr,
246 &ct->tuplehash[!dir].tuple.dst.u3,
247 htons((port & htons(1)) ? nated_port + 1 :
250 info->rtp_port[i][dir] = rtp_port;
251 info->rtp_port[i][!dir] = htons(nated_port);
253 nf_ct_unexpect_related(rtp_exp);
254 nf_ct_unexpect_related(rtcp_exp);
259 pr_debug("nf_nat_h323: expect RTP %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
260 NIPQUAD(rtp_exp->tuple.src.u3.ip),
261 ntohs(rtp_exp->tuple.src.u.udp.port),
262 NIPQUAD(rtp_exp->tuple.dst.u3.ip),
263 ntohs(rtp_exp->tuple.dst.u.udp.port));
264 pr_debug("nf_nat_h323: expect RTCP %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
265 NIPQUAD(rtcp_exp->tuple.src.u3.ip),
266 ntohs(rtcp_exp->tuple.src.u.udp.port),
267 NIPQUAD(rtcp_exp->tuple.dst.u3.ip),
268 ntohs(rtcp_exp->tuple.dst.u.udp.port));
273 /****************************************************************************/
274 static int nat_t120(struct sk_buff *skb, struct nf_conn *ct,
275 enum ip_conntrack_info ctinfo,
276 unsigned char **data, int dataoff,
277 H245_TransportAddress *taddr, __be16 port,
278 struct nf_conntrack_expect *exp)
280 int dir = CTINFO2DIR(ctinfo);
281 u_int16_t nated_port = ntohs(port);
283 /* Set expectations for NAT */
284 exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
285 exp->expectfn = nf_nat_follow_master;
288 /* Try to get same port: if not, try to change it. */
289 for (; nated_port != 0; nated_port++) {
290 exp->tuple.dst.u.tcp.port = htons(nated_port);
291 if (nf_ct_expect_related(exp) == 0)
295 if (nated_port == 0) { /* No port available */
297 printk("nf_nat_h323: out of TCP ports\n");
302 if (set_h245_addr(skb, data, dataoff, taddr,
303 &ct->tuplehash[!dir].tuple.dst.u3,
304 htons(nated_port)) < 0) {
305 nf_ct_unexpect_related(exp);
309 pr_debug("nf_nat_h323: expect T.120 %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
310 NIPQUAD(exp->tuple.src.u3.ip),
311 ntohs(exp->tuple.src.u.tcp.port),
312 NIPQUAD(exp->tuple.dst.u3.ip),
313 ntohs(exp->tuple.dst.u.tcp.port));
318 /****************************************************************************/
319 static int nat_h245(struct sk_buff *skb, struct nf_conn *ct,
320 enum ip_conntrack_info ctinfo,
321 unsigned char **data, int dataoff,
322 TransportAddress *taddr, __be16 port,
323 struct nf_conntrack_expect *exp)
325 struct nf_ct_h323_master *info = &nfct_help(ct)->help.ct_h323_info;
326 int dir = CTINFO2DIR(ctinfo);
327 u_int16_t nated_port = ntohs(port);
329 /* Set expectations for NAT */
330 exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
331 exp->expectfn = nf_nat_follow_master;
334 /* Check existing expects */
335 if (info->sig_port[dir] == port)
336 nated_port = ntohs(info->sig_port[!dir]);
338 /* Try to get same port: if not, try to change it. */
339 for (; nated_port != 0; nated_port++) {
340 exp->tuple.dst.u.tcp.port = htons(nated_port);
341 if (nf_ct_expect_related(exp) == 0)
345 if (nated_port == 0) { /* No port available */
347 printk("nf_nat_q931: out of TCP ports\n");
352 if (set_h225_addr(skb, data, dataoff, taddr,
353 &ct->tuplehash[!dir].tuple.dst.u3,
354 htons(nated_port)) == 0) {
356 info->sig_port[dir] = port;
357 info->sig_port[!dir] = htons(nated_port);
359 nf_ct_unexpect_related(exp);
363 pr_debug("nf_nat_q931: expect H.245 %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
364 NIPQUAD(exp->tuple.src.u3.ip),
365 ntohs(exp->tuple.src.u.tcp.port),
366 NIPQUAD(exp->tuple.dst.u3.ip),
367 ntohs(exp->tuple.dst.u.tcp.port));
372 /****************************************************************************
373 * This conntrack expect function replaces nf_conntrack_q931_expect()
374 * which was set by nf_conntrack_h323.c.
375 ****************************************************************************/
376 static void ip_nat_q931_expect(struct nf_conn *new,
377 struct nf_conntrack_expect *this)
379 struct nf_nat_range range;
381 if (this->tuple.src.u3.ip != 0) { /* Only accept calls from GK */
382 nf_nat_follow_master(new, this);
386 /* This must be a fresh one. */
387 BUG_ON(new->status & IPS_NAT_DONE_MASK);
389 /* Change src to where master sends to */
390 range.flags = IP_NAT_RANGE_MAP_IPS;
391 range.min_ip = range.max_ip = new->tuplehash[!this->dir].tuple.src.u3.ip;
392 nf_nat_setup_info(new, &range, IP_NAT_MANIP_SRC);
394 /* For DST manip, map port here to where it's expected. */
395 range.flags = (IP_NAT_RANGE_MAP_IPS | IP_NAT_RANGE_PROTO_SPECIFIED);
396 range.min = range.max = this->saved_proto;
397 range.min_ip = range.max_ip =
398 new->master->tuplehash[!this->dir].tuple.src.u3.ip;
399 nf_nat_setup_info(new, &range, IP_NAT_MANIP_DST);
402 /****************************************************************************/
403 static int nat_q931(struct sk_buff *skb, struct nf_conn *ct,
404 enum ip_conntrack_info ctinfo,
405 unsigned char **data, TransportAddress *taddr, int idx,
406 __be16 port, struct nf_conntrack_expect *exp)
408 struct nf_ct_h323_master *info = &nfct_help(ct)->help.ct_h323_info;
409 int dir = CTINFO2DIR(ctinfo);
410 u_int16_t nated_port = ntohs(port);
411 union nf_conntrack_address addr;
413 /* Set expectations for NAT */
414 exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
415 exp->expectfn = ip_nat_q931_expect;
418 /* Check existing expects */
419 if (info->sig_port[dir] == port)
420 nated_port = ntohs(info->sig_port[!dir]);
422 /* Try to get same port: if not, try to change it. */
423 for (; nated_port != 0; nated_port++) {
424 exp->tuple.dst.u.tcp.port = htons(nated_port);
425 if (nf_ct_expect_related(exp) == 0)
429 if (nated_port == 0) { /* No port available */
431 printk("nf_nat_ras: out of TCP ports\n");
436 if (set_h225_addr(skb, data, 0, &taddr[idx],
437 &ct->tuplehash[!dir].tuple.dst.u3,
438 htons(nated_port)) == 0) {
440 info->sig_port[dir] = port;
441 info->sig_port[!dir] = htons(nated_port);
443 /* Fix for Gnomemeeting */
445 get_h225_addr(ct, *data, &taddr[0], &addr, &port) &&
446 (ntohl(addr.ip) & 0xff000000) == 0x7f000000) {
447 set_h225_addr(skb, data, 0, &taddr[0],
448 &ct->tuplehash[!dir].tuple.dst.u3,
449 info->sig_port[!dir]);
452 nf_ct_unexpect_related(exp);
457 pr_debug("nf_nat_ras: expect Q.931 %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
458 NIPQUAD(exp->tuple.src.u3.ip),
459 ntohs(exp->tuple.src.u.tcp.port),
460 NIPQUAD(exp->tuple.dst.u3.ip),
461 ntohs(exp->tuple.dst.u.tcp.port));
466 /****************************************************************************/
467 static void ip_nat_callforwarding_expect(struct nf_conn *new,
468 struct nf_conntrack_expect *this)
470 struct nf_nat_range range;
472 /* This must be a fresh one. */
473 BUG_ON(new->status & IPS_NAT_DONE_MASK);
475 /* Change src to where master sends to */
476 range.flags = IP_NAT_RANGE_MAP_IPS;
477 range.min_ip = range.max_ip = new->tuplehash[!this->dir].tuple.src.u3.ip;
478 nf_nat_setup_info(new, &range, IP_NAT_MANIP_SRC);
480 /* For DST manip, map port here to where it's expected. */
481 range.flags = (IP_NAT_RANGE_MAP_IPS | IP_NAT_RANGE_PROTO_SPECIFIED);
482 range.min = range.max = this->saved_proto;
483 range.min_ip = range.max_ip = this->saved_ip;
484 nf_nat_setup_info(new, &range, IP_NAT_MANIP_DST);
487 /****************************************************************************/
488 static int nat_callforwarding(struct sk_buff *skb, struct nf_conn *ct,
489 enum ip_conntrack_info ctinfo,
490 unsigned char **data, int dataoff,
491 TransportAddress *taddr, __be16 port,
492 struct nf_conntrack_expect *exp)
494 int dir = CTINFO2DIR(ctinfo);
495 u_int16_t nated_port;
497 /* Set expectations for NAT */
498 exp->saved_ip = exp->tuple.dst.u3.ip;
499 exp->tuple.dst.u3.ip = ct->tuplehash[!dir].tuple.dst.u3.ip;
500 exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
501 exp->expectfn = ip_nat_callforwarding_expect;
504 /* Try to get same port: if not, try to change it. */
505 for (nated_port = ntohs(port); nated_port != 0; nated_port++) {
506 exp->tuple.dst.u.tcp.port = htons(nated_port);
507 if (nf_ct_expect_related(exp) == 0)
511 if (nated_port == 0) { /* No port available */
513 printk("nf_nat_q931: out of TCP ports\n");
518 if (!set_h225_addr(skb, data, dataoff, taddr,
519 &ct->tuplehash[!dir].tuple.dst.u3,
520 htons(nated_port)) == 0) {
521 nf_ct_unexpect_related(exp);
526 pr_debug("nf_nat_q931: expect Call Forwarding "
527 "%u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
528 NIPQUAD(exp->tuple.src.u3.ip),
529 ntohs(exp->tuple.src.u.tcp.port),
530 NIPQUAD(exp->tuple.dst.u3.ip),
531 ntohs(exp->tuple.dst.u.tcp.port));
536 /****************************************************************************/
537 static int __init init(void)
539 BUG_ON(set_h245_addr_hook != NULL);
540 BUG_ON(set_h225_addr_hook != NULL);
541 BUG_ON(set_sig_addr_hook != NULL);
542 BUG_ON(set_ras_addr_hook != NULL);
543 BUG_ON(nat_rtp_rtcp_hook != NULL);
544 BUG_ON(nat_t120_hook != NULL);
545 BUG_ON(nat_h245_hook != NULL);
546 BUG_ON(nat_callforwarding_hook != NULL);
547 BUG_ON(nat_q931_hook != NULL);
549 rcu_assign_pointer(set_h245_addr_hook, set_h245_addr);
550 rcu_assign_pointer(set_h225_addr_hook, set_h225_addr);
551 rcu_assign_pointer(set_sig_addr_hook, set_sig_addr);
552 rcu_assign_pointer(set_ras_addr_hook, set_ras_addr);
553 rcu_assign_pointer(nat_rtp_rtcp_hook, nat_rtp_rtcp);
554 rcu_assign_pointer(nat_t120_hook, nat_t120);
555 rcu_assign_pointer(nat_h245_hook, nat_h245);
556 rcu_assign_pointer(nat_callforwarding_hook, nat_callforwarding);
557 rcu_assign_pointer(nat_q931_hook, nat_q931);
561 /****************************************************************************/
562 static void __exit fini(void)
564 rcu_assign_pointer(set_h245_addr_hook, NULL);
565 rcu_assign_pointer(set_h225_addr_hook, NULL);
566 rcu_assign_pointer(set_sig_addr_hook, NULL);
567 rcu_assign_pointer(set_ras_addr_hook, NULL);
568 rcu_assign_pointer(nat_rtp_rtcp_hook, NULL);
569 rcu_assign_pointer(nat_t120_hook, NULL);
570 rcu_assign_pointer(nat_h245_hook, NULL);
571 rcu_assign_pointer(nat_callforwarding_hook, NULL);
572 rcu_assign_pointer(nat_q931_hook, NULL);
576 /****************************************************************************/
580 MODULE_AUTHOR("Jing Min Zhao <zhaojingmin@users.sourceforge.net>");
581 MODULE_DESCRIPTION("H.323 NAT helper");
582 MODULE_LICENSE("GPL");
583 MODULE_ALIAS("ip_nat_h323");