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/*
* H.323 'brute force' extension for H.323 connection tracking.
* Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
*
* Based on ip_masq_h323.c for 2.2 kernels from CoRiTel, Sofia project.
* (http://www.coritel.it/projects/sofia/nat/)
* Uses Sampsa Ranta's excellent idea on using expectfn to 'bind'
* the unregistered helpers to the conntrack entries.
*/
#include <linux/module.h>
#include <linux/netfilter.h>
#include <linux/ip.h>
#include <net/checksum.h>
#include <net/tcp.h>
#include <linux/netfilter_ipv4/lockhelp.h>
#include <linux/netfilter_ipv4/ip_conntrack.h>
#include <linux/netfilter_ipv4/ip_conntrack_core.h>
#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
#include <linux/netfilter_ipv4/ip_conntrack_tuple.h>
#include <linux/netfilter_ipv4/ip_conntrack_h323.h>
MODULE_AUTHOR("Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>");
MODULE_DESCRIPTION("H.323 'brute force' connection tracking module");
MODULE_LICENSE("GPL");
DECLARE_LOCK(ip_h323_lock);
struct module *ip_conntrack_h323 = THIS_MODULE;
#if 0
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif
/* FIXME: This should be in userspace. Later. */
static int h245_help(const struct iphdr *iph, size_t len,
struct ip_conntrack *ct,
enum ip_conntrack_info ctinfo)
{
struct tcphdr *tcph = (void *)iph + iph->ihl * 4;
unsigned char *data = (unsigned char *) tcph + tcph->doff * 4;
unsigned char *data_limit;
u_int32_t tcplen = len - iph->ihl * 4;
u_int32_t datalen = tcplen - tcph->doff * 4;
int dir = CTINFO2DIR(ctinfo);
struct ip_ct_h225_master *info = &ct->help.ct_h225_info;
struct ip_conntrack_expect expect, *exp = &expect;
struct ip_ct_h225_expect *exp_info = &exp->help.exp_h225_info;
u_int16_t data_port;
u_int32_t data_ip;
unsigned int i;
DEBUGP("ct_h245_help: help entered %u.%u.%u.%u:%u->%u.%u.%u.%u:%u\n",
NIPQUAD(iph->saddr), ntohs(tcph->source),
NIPQUAD(iph->daddr), ntohs(tcph->dest));
/* Can't track connections formed before we registered */
if (!info)
return NF_ACCEPT;
/* Until there's been traffic both ways, don't look in packets. */
if (ctinfo != IP_CT_ESTABLISHED
&& ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY) {
DEBUGP("ct_h245_help: Conntrackinfo = %u\n", ctinfo);
return NF_ACCEPT;
}
/* Not whole TCP header or too short packet? */
if (tcplen < sizeof(struct tcphdr) || tcplen < tcph->doff * 4 + 5) {
DEBUGP("ct_h245_help: tcplen = %u\n", (unsigned)tcplen);
return NF_ACCEPT;
}
/* Checksum invalid? Ignore. */
/* FIXME: Source route IP option packets --RR */
if (tcp_v4_check(tcph, tcplen, iph->saddr, iph->daddr,
csum_partial((char *)tcph, tcplen, 0))) {
DEBUGP("ct_h245_help: bad csum: %p %u %u.%u.%u.%u %u.%u.%u.%u\n",
tcph, tcplen, NIPQUAD(iph->saddr),
NIPQUAD(iph->daddr));
return NF_ACCEPT;
}
data_limit = (unsigned char *) data + datalen;
/* bytes: 0123 45
ipadrr port */
for (i = 0; data < (data_limit - 5); data++, i++) {
data_ip = *((u_int32_t *)data);
if (data_ip == iph->saddr) {
data_port = *((u_int16_t *)(data + 4));
memset(&expect, 0, sizeof(expect));
/* update the H.225 info */
DEBUGP("ct_h245_help: new RTCP/RTP requested %u.%u.%u.%u:->%u.%u.%u.%u:%u\n",
NIPQUAD(ct->tuplehash[!dir].tuple.src.ip),
NIPQUAD(iph->saddr), ntohs(data_port));
LOCK_BH(&ip_h323_lock);
info->is_h225 = H225_PORT + 1;
exp_info->port = data_port;
exp_info->dir = dir;
exp_info->offset = i;
exp->seq = ntohl(tcph->seq) + i;
*((u_int32_t *)data) = ct->tuplehash[!dir].tuple.dst.ip; //!!! Netmeeting fix
{
unsigned int chksum;
chksum = csum_partial((char *)tcph + tcph->doff*4,
datalen, 0);
tcph->check = 0;
tcph->check = tcp_v4_check(tcph, tcplen, iph->saddr, iph->daddr,
csum_partial((char *)tcph, tcph->doff*4, chksum));
}
exp->tuple = ((struct ip_conntrack_tuple)
{ { ct->tuplehash[!dir].tuple.src.ip,
{ 0 } },
{ data_ip,
{ data_port },
IPPROTO_UDP }});
exp->mask = ((struct ip_conntrack_tuple)
{ { 0xFFFFFFFF, { 0 } },
{ 0xFFFFFFFF, { 0xFFFF }, 0xFFFF }});
exp->expectfn = NULL;
/* Ignore failure; should only happen with NAT */
ip_conntrack_expect_related(ct, exp);
UNLOCK_BH(&ip_h323_lock);
}
}
return NF_ACCEPT;
}
/* H.245 helper is not registered! */
static struct ip_conntrack_helper h245 =
{ { NULL, NULL },
"H.245", /* name */
IP_CT_HELPER_F_REUSE_EXPECT, /* flags */
NULL, /* module */
8, /* max_ expected */
240, /* timeout */
{ { 0, { 0 } }, /* tuple */
{ 0, { 0 }, IPPROTO_TCP } },
{ { 0, { 0xFFFF } }, /* mask */
{ 0, { 0 }, 0xFFFF } },
h245_help /* helper */
};
static int h225_expect(struct ip_conntrack *ct)
{
WRITE_LOCK(&ip_conntrack_lock);
ct->helper = &h245;
DEBUGP("h225_expect: helper for %p added\n", ct);
WRITE_UNLOCK(&ip_conntrack_lock);
return NF_ACCEPT; /* unused */
}
/* FIXME: This should be in userspace. Later. */
static int h225_help(const struct iphdr *iph, size_t len,
struct ip_conntrack *ct,
enum ip_conntrack_info ctinfo)
{
struct tcphdr *tcph = (void *)iph + iph->ihl * 4;
unsigned char *data = (unsigned char *) tcph + tcph->doff * 4;
unsigned char *data_limit;
u_int32_t tcplen = len - iph->ihl * 4;
u_int32_t datalen = tcplen - tcph->doff * 4;
int dir = CTINFO2DIR(ctinfo);
struct ip_ct_h225_master *info = &ct->help.ct_h225_info;
struct ip_conntrack_expect expect, *exp = &expect;
struct ip_ct_h225_expect *exp_info = &exp->help.exp_h225_info;
u_int16_t data_port;
u_int32_t data_ip;
unsigned int i;
DEBUGP("ct_h225_help: help entered %u.%u.%u.%u:%u->%u.%u.%u.%u:%u\n",
NIPQUAD(iph->saddr), ntohs(tcph->source),
NIPQUAD(iph->daddr), ntohs(tcph->dest));
/* Can't track connections formed before we registered */
if (!info)
return NF_ACCEPT;
/* Until there's been traffic both ways, don't look in packets. */
if (ctinfo != IP_CT_ESTABLISHED
&& ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY) {
DEBUGP("ct_h225_help: Conntrackinfo = %u\n", ctinfo);
return NF_ACCEPT;
}
/* Not whole TCP header or too short packet? */
if (tcplen < sizeof(struct tcphdr) || tcplen < tcph->doff * 4 + 5) {
DEBUGP("ct_h225_help: tcplen = %u\n", (unsigned)tcplen);
return NF_ACCEPT;
}
/* Checksum invalid? Ignore. */
/* FIXME: Source route IP option packets --RR */
if (tcp_v4_check(tcph, tcplen, iph->saddr, iph->daddr,
csum_partial((char *)tcph, tcplen, 0))) {
DEBUGP("ct_h225_help: bad csum: %p %u %u.%u.%u.%u %u.%u.%u.%u\n",
tcph, tcplen, NIPQUAD(iph->saddr),
NIPQUAD(iph->daddr));
return NF_ACCEPT;
}
data_limit = (unsigned char *) data + datalen;
/* bytes: 0123 45
ipadrr port */
for (i = 0; data < (data_limit - 5); data++, i++) {
data_ip = *((u_int32_t *)data);
if (data_ip == iph->saddr) {
data_port = *((u_int16_t *)(data + 4));
if (data_port == tcph->source) {
/* Signal address */
DEBUGP("ct_h225_help: sourceCallSignalAddress from %u.%u.%u.%u\n",
NIPQUAD(iph->saddr));
/* Update the H.225 info so that NAT can mangle the address/port
even when we have no expected connection! */
#ifdef CONFIG_IP_NF_NAT_NEEDED
LOCK_BH(&ip_h323_lock);
info->dir = dir;
info->seq[IP_CT_DIR_ORIGINAL] = ntohl(tcph->seq) + i;
info->offset[IP_CT_DIR_ORIGINAL] = i;
UNLOCK_BH(&ip_h323_lock);
#endif
} else {
memset(&expect, 0, sizeof(expect));
/* update the H.225 info */
LOCK_BH(&ip_h323_lock);
info->is_h225 = H225_PORT;
exp_info->port = data_port;
exp_info->dir = dir;
exp_info->offset = i;
exp->seq = ntohl(tcph->seq) + i;
exp->tuple = ((struct ip_conntrack_tuple)
{ { ct->tuplehash[!dir].tuple.src.ip,
{ 0 } },
{ data_ip,
{ data_port },
IPPROTO_TCP }});
exp->mask = ((struct ip_conntrack_tuple)
{ { 0xFFFFFFFF, { 0 } },
{ 0xFFFFFFFF, { 0xFFFF }, 0xFFFF }});
exp->expectfn = h225_expect;
/* Ignore failure */
ip_conntrack_expect_related(ct, exp);
DEBUGP("ct_h225_help: new H.245 requested %u.%u.%u.%u->%u.%u.%u.%u:%u\n",
NIPQUAD(ct->tuplehash[!dir].tuple.src.ip),
NIPQUAD(iph->saddr), ntohs(data_port));
UNLOCK_BH(&ip_h323_lock);
}
#ifdef CONFIG_IP_NF_NAT_NEEDED
} else if (data_ip == iph->daddr) {
data_port = *((u_int16_t *)(data + 4));
if (data_port == tcph->dest) {
/* Signal address */
DEBUGP("ct_h225_help: destCallSignalAddress %u.%u.%u.%u\n",
NIPQUAD(iph->daddr));
/* Update the H.225 info so that NAT can mangle the address/port
even when we have no expected connection! */
LOCK_BH(&ip_h323_lock);
info->dir = dir;
info->seq[IP_CT_DIR_REPLY] = ntohl(tcph->seq) + i;
info->offset[IP_CT_DIR_REPLY] = i;
UNLOCK_BH(&ip_h323_lock);
}
#endif
}
}
return NF_ACCEPT;
}
static struct ip_conntrack_helper h225 =
{ { NULL, NULL },
"H.225", /* name */
IP_CT_HELPER_F_REUSE_EXPECT, /* flags */
THIS_MODULE, /* module */
2, /* max_expected */
240, /* timeout */
{ { 0, { __constant_htons(H225_PORT) } }, /* tuple */
{ 0, { 0 }, IPPROTO_TCP } },
{ { 0, { 0xFFFF } }, /* mask */
{ 0, { 0 }, 0xFFFF } },
h225_help /* helper */
};
static int __init init(void)
{
return ip_conntrack_helper_register(&h225);
}
static void __exit fini(void)
{
/* Unregister H.225 helper */
ip_conntrack_helper_unregister(&h225);
}
#ifdef CONFIG_IP_NF_NAT_NEEDED
EXPORT_SYMBOL(ip_h323_lock);
#endif
module_init(init);
module_exit(fini);
|
