--- /dev/null
+/*
+ * H.323 extension for NAT alteration.
+ *
+ * Copyright (c) 2006 Jing Min Zhao <zhaojingmin@users.sourceforge.net>
+ *
+ * This source code is licensed under General Public License version 2.
+ *
+ * Based on the 'brute force' H.323 NAT module by
+ * Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
+ */
+
+#include <linux/module.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/netfilter.h>
+#include <linux/ip.h>
+#include <linux/tcp.h>
+#include <linux/moduleparam.h>
+#include <net/tcp.h>
+#include <linux/netfilter_ipv4/ip_nat.h>
+#include <linux/netfilter_ipv4/ip_nat_helper.h>
+#include <linux/netfilter_ipv4/ip_nat_rule.h>
+#include <linux/netfilter_ipv4/ip_conntrack_tuple.h>
+#include <linux/netfilter_ipv4/ip_conntrack_h323.h>
+#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
+
+#if 0
+#define DEBUGP printk
+#else
+#define DEBUGP(format, args...)
+#endif
+
+/****************************************************************************/
+static int set_addr(struct sk_buff **pskb,
+ unsigned char **data, int dataoff,
+ unsigned int addroff, u_int32_t ip, u_int16_t port)
+{
+ enum ip_conntrack_info ctinfo;
+ struct ip_conntrack *ct = ip_conntrack_get(*pskb, &ctinfo);
+ struct {
+ u_int32_t ip;
+ u_int16_t port;
+ } __attribute__ ((__packed__)) buf;
+ struct tcphdr _tcph, *th;
+
+ buf.ip = ip;
+ buf.port = htons(port);
+ addroff += dataoff;
+
+ if ((*pskb)->nh.iph->protocol == IPPROTO_TCP) {
+ if (!ip_nat_mangle_tcp_packet(pskb, ct, ctinfo,
+ addroff, sizeof(buf),
+ (char *) &buf, sizeof(buf))) {
+ if (net_ratelimit())
+ printk("ip_nat_h323: ip_nat_mangle_tcp_packet"
+ " error\n");
+ return -1;
+ }
+
+ /* Relocate data pointer */
+ th = skb_header_pointer(*pskb, (*pskb)->nh.iph->ihl * 4,
+ sizeof(_tcph), &_tcph);
+ if (th == NULL)
+ return -1;
+ *data = (*pskb)->data + (*pskb)->nh.iph->ihl * 4 +
+ th->doff * 4 + dataoff;
+ } else {
+ if (!ip_nat_mangle_udp_packet(pskb, ct, ctinfo,
+ addroff, sizeof(buf),
+ (char *) &buf, sizeof(buf))) {
+ if (net_ratelimit())
+ printk("ip_nat_h323: ip_nat_mangle_udp_packet"
+ " error\n");
+ return -1;
+ }
+ /* ip_nat_mangle_udp_packet uses skb_make_writable() to copy
+ * or pull everything in a linear buffer, so we can safely
+ * use the skb pointers now */
+ *data = (*pskb)->data + (*pskb)->nh.iph->ihl * 4 +
+ sizeof(struct udphdr);
+ }
+
+ return 0;
+}
+
+/****************************************************************************/
+static int set_h225_addr(struct sk_buff **pskb,
+ unsigned char **data, int dataoff,
+ TransportAddress * addr,
+ u_int32_t ip, u_int16_t port)
+{
+ return set_addr(pskb, data, dataoff, addr->ipAddress.ip, ip, port);
+}
+
+/****************************************************************************/
+static int set_h245_addr(struct sk_buff **pskb,
+ unsigned char **data, int dataoff,
+ H245_TransportAddress * addr,
+ u_int32_t ip, u_int16_t port)
+{
+ return set_addr(pskb, data, dataoff,
+ addr->unicastAddress.iPAddress.network, ip, port);
+}
+
+/****************************************************************************/
+static int set_sig_addr(struct sk_buff **pskb, struct ip_conntrack *ct,
+ enum ip_conntrack_info ctinfo,
+ unsigned char **data,
+ TransportAddress * addr, int count)
+{
+ struct ip_ct_h323_master *info = &ct->help.ct_h323_info;
+ int dir = CTINFO2DIR(ctinfo);
+ int i;
+ u_int32_t ip;
+ u_int16_t port;
+
+ for (i = 0; i < count; i++) {
+ if (get_h225_addr(*data, &addr[i], &ip, &port)) {
+ if (ip == ct->tuplehash[dir].tuple.src.ip &&
+ port == info->sig_port[dir]) {
+ /* GW->GK */
+
+ /* Fix for Gnomemeeting */
+ if (i > 0 &&
+ get_h225_addr(*data, &addr[0],
+ &ip, &port) &&
+ (ntohl(ip) & 0xff000000) == 0x7f000000)
+ i = 0;
+
+ DEBUGP
+ ("ip_nat_ras: set signal address "
+ "%u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+ NIPQUAD(ip), port,
+ NIPQUAD(ct->tuplehash[!dir].tuple.dst.
+ ip), info->sig_port[!dir]);
+ return set_h225_addr(pskb, data, 0, &addr[i],
+ ct->tuplehash[!dir].
+ tuple.dst.ip,
+ info->sig_port[!dir]);
+ } else if (ip == ct->tuplehash[dir].tuple.dst.ip &&
+ port == info->sig_port[dir]) {
+ /* GK->GW */
+ DEBUGP
+ ("ip_nat_ras: set signal address "
+ "%u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+ NIPQUAD(ip), port,
+ NIPQUAD(ct->tuplehash[!dir].tuple.src.
+ ip), info->sig_port[!dir]);
+ return set_h225_addr(pskb, data, 0, &addr[i],
+ ct->tuplehash[!dir].
+ tuple.src.ip,
+ info->sig_port[!dir]);
+ }
+ }
+ }
+
+ return 0;
+}
+
+/****************************************************************************/
+static int set_ras_addr(struct sk_buff **pskb, struct ip_conntrack *ct,
+ enum ip_conntrack_info ctinfo,
+ unsigned char **data,
+ TransportAddress * addr, int count)
+{
+ int dir = CTINFO2DIR(ctinfo);
+ int i;
+ u_int32_t ip;
+ u_int16_t port;
+
+ for (i = 0; i < count; i++) {
+ if (get_h225_addr(*data, &addr[i], &ip, &port) &&
+ ip == ct->tuplehash[dir].tuple.src.ip &&
+ port == ntohs(ct->tuplehash[dir].tuple.src.u.udp.port)) {
+ DEBUGP("ip_nat_ras: set rasAddress "
+ "%u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+ NIPQUAD(ip), port,
+ NIPQUAD(ct->tuplehash[!dir].tuple.dst.ip),
+ ntohs(ct->tuplehash[!dir].tuple.dst.u.udp.
+ port));
+ return set_h225_addr(pskb, data, 0, &addr[i],
+ ct->tuplehash[!dir].tuple.dst.ip,
+ ntohs(ct->tuplehash[!dir].tuple.
+ dst.u.udp.port));
+ }
+ }
+
+ return 0;
+}
+
+/****************************************************************************/
+static int nat_rtp_rtcp(struct sk_buff **pskb, struct ip_conntrack *ct,
+ enum ip_conntrack_info ctinfo,
+ unsigned char **data, int dataoff,
+ H245_TransportAddress * addr,
+ u_int16_t port, u_int16_t rtp_port,
+ struct ip_conntrack_expect *rtp_exp,
+ struct ip_conntrack_expect *rtcp_exp)
+{
+ struct ip_ct_h323_master *info = &ct->help.ct_h323_info;
+ int dir = CTINFO2DIR(ctinfo);
+ int i;
+ u_int16_t nated_port;
+
+ /* Set expectations for NAT */
+ rtp_exp->saved_proto.udp.port = rtp_exp->tuple.dst.u.udp.port;
+ rtp_exp->expectfn = ip_nat_follow_master;
+ rtp_exp->dir = !dir;
+ rtcp_exp->saved_proto.udp.port = rtcp_exp->tuple.dst.u.udp.port;
+ rtcp_exp->expectfn = ip_nat_follow_master;
+ rtcp_exp->dir = !dir;
+
+ /* Lookup existing expects */
+ for (i = 0; i < H323_RTP_CHANNEL_MAX; i++) {
+ if (info->rtp_port[i][dir] == rtp_port) {
+ /* Expected */
+
+ /* Use allocated ports first. This will refresh
+ * the expects */
+ rtp_exp->tuple.dst.u.udp.port =
+ htons(info->rtp_port[i][dir]);
+ rtcp_exp->tuple.dst.u.udp.port =
+ htons(info->rtp_port[i][dir] + 1);
+ break;
+ } else if (info->rtp_port[i][dir] == 0) {
+ /* Not expected */
+ break;
+ }
+ }
+
+ /* Run out of expectations */
+ if (i >= H323_RTP_CHANNEL_MAX) {
+ if (net_ratelimit())
+ printk("ip_nat_h323: out of expectations\n");
+ return 0;
+ }
+
+ /* Try to get a pair of ports. */
+ for (nated_port = ntohs(rtp_exp->tuple.dst.u.udp.port);
+ nated_port != 0; nated_port += 2) {
+ rtp_exp->tuple.dst.u.udp.port = htons(nated_port);
+ if (ip_conntrack_expect_related(rtp_exp) == 0) {
+ rtcp_exp->tuple.dst.u.udp.port =
+ htons(nated_port + 1);
+ if (ip_conntrack_expect_related(rtcp_exp) == 0)
+ break;
+ ip_conntrack_unexpect_related(rtp_exp);
+ }
+ }
+
+ if (nated_port == 0) { /* No port available */
+ if (net_ratelimit())
+ printk("ip_nat_h323: out of RTP ports\n");
+ return 0;
+ }
+
+ /* Modify signal */
+ if (set_h245_addr(pskb, data, dataoff, addr,
+ ct->tuplehash[!dir].tuple.dst.ip,
+ (port & 1) ? nated_port + 1 : nated_port) == 0) {
+ /* Save ports */
+ info->rtp_port[i][dir] = rtp_port;
+ info->rtp_port[i][!dir] = nated_port;
+ } else {
+ ip_conntrack_unexpect_related(rtp_exp);
+ ip_conntrack_unexpect_related(rtcp_exp);
+ return -1;
+ }
+
+ /* Success */
+ DEBUGP("ip_nat_h323: expect RTP %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+ NIPQUAD(rtp_exp->tuple.src.ip),
+ ntohs(rtp_exp->tuple.src.u.udp.port),
+ NIPQUAD(rtp_exp->tuple.dst.ip),
+ ntohs(rtp_exp->tuple.dst.u.udp.port));
+ DEBUGP("ip_nat_h323: expect RTCP %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+ NIPQUAD(rtcp_exp->tuple.src.ip),
+ ntohs(rtcp_exp->tuple.src.u.udp.port),
+ NIPQUAD(rtcp_exp->tuple.dst.ip),
+ ntohs(rtcp_exp->tuple.dst.u.udp.port));
+
+ return 0;
+}
+
+/****************************************************************************/
+static int nat_t120(struct sk_buff **pskb, struct ip_conntrack *ct,
+ enum ip_conntrack_info ctinfo,
+ unsigned char **data, int dataoff,
+ H245_TransportAddress * addr, u_int16_t port,
+ struct ip_conntrack_expect *exp)
+{
+ int dir = CTINFO2DIR(ctinfo);
+ u_int16_t nated_port = port;
+
+ /* Set expectations for NAT */
+ exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
+ exp->expectfn = ip_nat_follow_master;
+ exp->dir = !dir;
+
+ /* Try to get same port: if not, try to change it. */
+ for (; nated_port != 0; nated_port++) {
+ exp->tuple.dst.u.tcp.port = htons(nated_port);
+ if (ip_conntrack_expect_related(exp) == 0)
+ break;
+ }
+
+ if (nated_port == 0) { /* No port available */
+ if (net_ratelimit())
+ printk("ip_nat_h323: out of TCP ports\n");
+ return 0;
+ }
+
+ /* Modify signal */
+ if (set_h245_addr(pskb, data, dataoff, addr,
+ ct->tuplehash[!dir].tuple.dst.ip, nated_port) < 0) {
+ ip_conntrack_unexpect_related(exp);
+ return -1;
+ }
+
+ DEBUGP("ip_nat_h323: expect T.120 %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+ NIPQUAD(exp->tuple.src.ip), ntohs(exp->tuple.src.u.tcp.port),
+ NIPQUAD(exp->tuple.dst.ip), ntohs(exp->tuple.dst.u.tcp.port));
+
+ return 0;
+}
+
+/****************************************************************************
+ * This conntrack expect function replaces ip_conntrack_h245_expect()
+ * which was set by ip_conntrack_helper_h323.c. It calls both
+ * ip_nat_follow_master() and ip_conntrack_h245_expect()
+ ****************************************************************************/
+static void ip_nat_h245_expect(struct ip_conntrack *new,
+ struct ip_conntrack_expect *this)
+{
+ ip_nat_follow_master(new, this);
+ ip_conntrack_h245_expect(new, this);
+}
+
+/****************************************************************************/
+static int nat_h245(struct sk_buff **pskb, struct ip_conntrack *ct,
+ enum ip_conntrack_info ctinfo,
+ unsigned char **data, int dataoff,
+ TransportAddress * addr, u_int16_t port,
+ struct ip_conntrack_expect *exp)
+{
+ struct ip_ct_h323_master *info = &ct->help.ct_h323_info;
+ int dir = CTINFO2DIR(ctinfo);
+ u_int16_t nated_port = port;
+
+ /* Set expectations for NAT */
+ exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
+ exp->expectfn = ip_nat_h245_expect;
+ exp->dir = !dir;
+
+ /* Check existing expects */
+ if (info->sig_port[dir] == port)
+ nated_port = info->sig_port[!dir];
+
+ /* Try to get same port: if not, try to change it. */
+ for (; nated_port != 0; nated_port++) {
+ exp->tuple.dst.u.tcp.port = htons(nated_port);
+ if (ip_conntrack_expect_related(exp) == 0)
+ break;
+ }
+
+ if (nated_port == 0) { /* No port available */
+ if (net_ratelimit())
+ printk("ip_nat_q931: out of TCP ports\n");
+ return 0;
+ }
+
+ /* Modify signal */
+ if (set_h225_addr(pskb, data, dataoff, addr,
+ ct->tuplehash[!dir].tuple.dst.ip,
+ nated_port) == 0) {
+ /* Save ports */
+ info->sig_port[dir] = port;
+ info->sig_port[!dir] = nated_port;
+ } else {
+ ip_conntrack_unexpect_related(exp);
+ return -1;
+ }
+
+ DEBUGP("ip_nat_q931: expect H.245 %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+ NIPQUAD(exp->tuple.src.ip), ntohs(exp->tuple.src.u.tcp.port),
+ NIPQUAD(exp->tuple.dst.ip), ntohs(exp->tuple.dst.u.tcp.port));
+
+ return 0;
+}
+
+/****************************************************************************
+ * This conntrack expect function replaces ip_conntrack_q931_expect()
+ * which was set by ip_conntrack_helper_h323.c.
+ ****************************************************************************/
+static void ip_nat_q931_expect(struct ip_conntrack *new,
+ struct ip_conntrack_expect *this)
+{
+ struct ip_nat_range range;
+
+ if (this->tuple.src.ip != 0) { /* Only accept calls from GK */
+ ip_nat_follow_master(new, this);
+ goto out;
+ }
+
+ /* This must be a fresh one. */
+ BUG_ON(new->status & IPS_NAT_DONE_MASK);
+
+ /* Change src to where master sends to */
+ range.flags = IP_NAT_RANGE_MAP_IPS;
+ range.min_ip = range.max_ip = new->tuplehash[!this->dir].tuple.src.ip;
+
+ /* hook doesn't matter, but it has to do source manip */
+ ip_nat_setup_info(new, &range, NF_IP_POST_ROUTING);
+
+ /* For DST manip, map port here to where it's expected. */
+ range.flags = (IP_NAT_RANGE_MAP_IPS | IP_NAT_RANGE_PROTO_SPECIFIED);
+ range.min = range.max = this->saved_proto;
+ range.min_ip = range.max_ip =
+ new->master->tuplehash[!this->dir].tuple.src.ip;
+
+ /* hook doesn't matter, but it has to do destination manip */
+ ip_nat_setup_info(new, &range, NF_IP_PRE_ROUTING);
+
+ out:
+ ip_conntrack_q931_expect(new, this);
+}
+
+/****************************************************************************/
+static int nat_q931(struct sk_buff **pskb, struct ip_conntrack *ct,
+ enum ip_conntrack_info ctinfo,
+ unsigned char **data, TransportAddress * addr, int idx,
+ u_int16_t port, struct ip_conntrack_expect *exp)
+{
+ struct ip_ct_h323_master *info = &ct->help.ct_h323_info;
+ int dir = CTINFO2DIR(ctinfo);
+ u_int16_t nated_port = port;
+ u_int32_t ip;
+
+ /* Set expectations for NAT */
+ exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
+ exp->expectfn = ip_nat_q931_expect;
+ exp->dir = !dir;
+
+ /* Check existing expects */
+ if (info->sig_port[dir] == port)
+ nated_port = info->sig_port[!dir];
+
+ /* Try to get same port: if not, try to change it. */
+ for (; nated_port != 0; nated_port++) {
+ exp->tuple.dst.u.tcp.port = htons(nated_port);
+ if (ip_conntrack_expect_related(exp) == 0)
+ break;
+ }
+
+ if (nated_port == 0) { /* No port available */
+ if (net_ratelimit())
+ printk("ip_nat_ras: out of TCP ports\n");
+ return 0;
+ }
+
+ /* Modify signal */
+ if (set_h225_addr(pskb, data, 0, &addr[idx],
+ ct->tuplehash[!dir].tuple.dst.ip,
+ nated_port) == 0) {
+ /* Save ports */
+ info->sig_port[dir] = port;
+ info->sig_port[!dir] = nated_port;
+
+ /* Fix for Gnomemeeting */
+ if (idx > 0 &&
+ get_h225_addr(*data, &addr[0], &ip, &port) &&
+ (ntohl(ip) & 0xff000000) == 0x7f000000) {
+ set_h225_addr_hook(pskb, data, 0, &addr[0],
+ ct->tuplehash[!dir].tuple.dst.ip,
+ info->sig_port[!dir]);
+ }
+ } else {
+ ip_conntrack_unexpect_related(exp);
+ return -1;
+ }
+
+ /* Success */
+ DEBUGP("ip_nat_ras: expect Q.931 %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+ NIPQUAD(exp->tuple.src.ip), ntohs(exp->tuple.src.u.tcp.port),
+ NIPQUAD(exp->tuple.dst.ip), ntohs(exp->tuple.dst.u.tcp.port));
+
+ return 0;
+}
+
+/****************************************************************************/
+static int __init init(void)
+{
+ BUG_ON(set_h245_addr_hook != NULL);
+ BUG_ON(set_h225_addr_hook != NULL);
+ BUG_ON(set_sig_addr_hook != NULL);
+ BUG_ON(set_ras_addr_hook != NULL);
+ BUG_ON(nat_rtp_rtcp_hook != NULL);
+ BUG_ON(nat_t120_hook != NULL);
+ BUG_ON(nat_h245_hook != NULL);
+ BUG_ON(nat_q931_hook != NULL);
+
+ set_h245_addr_hook = set_h245_addr;
+ set_h225_addr_hook = set_h225_addr;
+ set_sig_addr_hook = set_sig_addr;
+ set_ras_addr_hook = set_ras_addr;
+ nat_rtp_rtcp_hook = nat_rtp_rtcp;
+ nat_t120_hook = nat_t120;
+ nat_h245_hook = nat_h245;
+ nat_q931_hook = nat_q931;
+
+ DEBUGP("ip_nat_h323: init success\n");
+ return 0;
+}
+
+/****************************************************************************/
+static void __exit fini(void)
+{
+ set_h245_addr_hook = NULL;
+ set_h225_addr_hook = NULL;
+ set_sig_addr_hook = NULL;
+ set_ras_addr_hook = NULL;
+ nat_rtp_rtcp_hook = NULL;
+ nat_t120_hook = NULL;
+ nat_h245_hook = NULL;
+ nat_q931_hook = NULL;
+ synchronize_net();
+}
+
+/****************************************************************************/
+module_init(init);
+module_exit(fini);
+
+MODULE_AUTHOR("Jing Min Zhao <zhaojingmin@users.sourceforge.net>");
+MODULE_DESCRIPTION("H.323 NAT helper");
+MODULE_LICENSE("GPL");
git://git.onelab.eu / linux-2.6.git / blobdiff