[net-next-2.6.git] / net / ipv4 / netfilter / nf_nat_sip.c

/* SIP extension for UDP NAT alteration.
 *
 * (C) 2005 by Christian Hentschel <chentschel@arnet.com.ar>
 * based on RR's ip_nat_ftp.c and other modules.
 * (C) 2007 United Security Providers
 * (C) 2007, 2008 Patrick McHardy <kaber@trash.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <net/ip.h>
#include <linux/udp.h>

#include <net/netfilter/nf_nat.h>
#include <net/netfilter/nf_nat_helper.h>
#include <net/netfilter/nf_nat_rule.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_expect.h>
#include <linux/netfilter/nf_conntrack_sip.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>");
MODULE_DESCRIPTION("SIP NAT helper");
MODULE_ALIAS("ip_nat_sip");


static unsigned int mangle_packet(struct sk_buff *skb, unsigned int dataoff,
				  const char **dptr, unsigned int *datalen,
				  unsigned int matchoff, unsigned int matchlen,
				  const char *buffer, unsigned int buflen)
{
	enum ip_conntrack_info ctinfo;
	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);

	if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo, matchoff, matchlen,
				      buffer, buflen))
		return 0;

	/* Reload data pointer and adjust datalen value */
	*dptr = skb->data + dataoff;
	*datalen += buflen - matchlen;
	return 1;
}

static int map_addr(struct sk_buff *skb, unsigned int dataoff,
		    const char **dptr, unsigned int *datalen,
		    unsigned int matchoff, unsigned int matchlen,
		    union nf_inet_addr *addr, __be16 port)
{
	enum ip_conntrack_info ctinfo;
	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
	unsigned int buflen;
	__be32 newaddr;
	__be16 newport;

	if (ct->tuplehash[dir].tuple.src.u3.ip == addr->ip &&
	    ct->tuplehash[dir].tuple.src.u.udp.port == port) {
		newaddr = ct->tuplehash[!dir].tuple.dst.u3.ip;
		newport = ct->tuplehash[!dir].tuple.dst.u.udp.port;
	} else if (ct->tuplehash[dir].tuple.dst.u3.ip == addr->ip &&
		   ct->tuplehash[dir].tuple.dst.u.udp.port == port) {
		newaddr = ct->tuplehash[!dir].tuple.src.u3.ip;
		newport = ct->tuplehash[!dir].tuple.src.u.udp.port;
	} else
		return 1;

	if (newaddr == addr->ip && newport == port)
		return 1;

	buflen = sprintf(buffer, "%pI4:%u", &newaddr, ntohs(newport));

	return mangle_packet(skb, dataoff, dptr, datalen, matchoff, matchlen,
			     buffer, buflen);
}

static int map_sip_addr(struct sk_buff *skb, unsigned int dataoff,
			const char **dptr, unsigned int *datalen,
			enum sip_header_types type)
{
	enum ip_conntrack_info ctinfo;
	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
	unsigned int matchlen, matchoff;
	union nf_inet_addr addr;
	__be16 port;

	if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen, type, NULL,
				    &matchoff, &matchlen, &addr, &port) <= 0)
		return 1;
	return map_addr(skb, dataoff, dptr, datalen, matchoff, matchlen,
			&addr, port);
}

static unsigned int ip_nat_sip(struct sk_buff *skb, unsigned int dataoff,
			       const char **dptr, unsigned int *datalen)
{
	enum ip_conntrack_info ctinfo;
	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	unsigned int coff, matchoff, matchlen;
	union nf_inet_addr addr;
	__be16 port;
	int request, in_header;

	/* Basic rules: requests and responses. */
	if (strnicmp(*dptr, "SIP/2.0", strlen("SIP/2.0")) != 0) {
		if (ct_sip_parse_request(ct, *dptr, *datalen,
					 &matchoff, &matchlen,
					 &addr, &port) > 0 &&
		    !map_addr(skb, dataoff, dptr, datalen, matchoff, matchlen,
			      &addr, port))
			return NF_DROP;
		request = 1;
	} else
		request = 0;

	/* Translate topmost Via header and parameters */
	if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen,
				    SIP_HDR_VIA, NULL, &matchoff, &matchlen,
				    &addr, &port) > 0) {
		unsigned int matchend, poff, plen, buflen, n;
		char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")];

		/* We're only interested in headers related to this
		 * connection */
		if (request) {
			if (addr.ip != ct->tuplehash[dir].tuple.src.u3.ip ||
			    port != ct->tuplehash[dir].tuple.src.u.udp.port)
				goto next;
		} else {
			if (addr.ip != ct->tuplehash[dir].tuple.dst.u3.ip ||
			    port != ct->tuplehash[dir].tuple.dst.u.udp.port)
				goto next;
		}

		if (!map_addr(skb, dataoff, dptr, datalen, matchoff, matchlen,
			      &addr, port))
			return NF_DROP;

		matchend = matchoff + matchlen;

		/* The maddr= parameter (RFC 2361) specifies where to send
		 * the reply. */
		if (ct_sip_parse_address_param(ct, *dptr, matchend, *datalen,
					       "maddr=", &poff, &plen,
					       &addr) > 0 &&
		    addr.ip == ct->tuplehash[dir].tuple.src.u3.ip &&
		    addr.ip != ct->tuplehash[!dir].tuple.dst.u3.ip) {
			buflen = sprintf(buffer, "%pI4",
					&ct->tuplehash[!dir].tuple.dst.u3.ip);
			if (!mangle_packet(skb, dataoff, dptr, datalen,
					   poff, plen, buffer, buflen))
				return NF_DROP;
		}

		/* The received= parameter (RFC 2361) contains the address
		 * from which the server received the request. */
		if (ct_sip_parse_address_param(ct, *dptr, matchend, *datalen,
					       "received=", &poff, &plen,
					       &addr) > 0 &&
		    addr.ip == ct->tuplehash[dir].tuple.dst.u3.ip &&
		    addr.ip != ct->tuplehash[!dir].tuple.src.u3.ip) {
			buflen = sprintf(buffer, "%pI4",
					&ct->tuplehash[!dir].tuple.src.u3.ip);
			if (!mangle_packet(skb, dataoff, dptr, datalen,
					   poff, plen, buffer, buflen))
				return NF_DROP;
		}

		/* The rport= parameter (RFC 3581) contains the port number
		 * from which the server received the request. */
		if (ct_sip_parse_numerical_param(ct, *dptr, matchend, *datalen,
						 "rport=", &poff, &plen,
						 &n) > 0 &&
		    htons(n) == ct->tuplehash[dir].tuple.dst.u.udp.port &&
		    htons(n) != ct->tuplehash[!dir].tuple.src.u.udp.port) {
			__be16 p = ct->tuplehash[!dir].tuple.src.u.udp.port;
			buflen = sprintf(buffer, "%u", ntohs(p));
			if (!mangle_packet(skb, dataoff, dptr, datalen,
					   poff, plen, buffer, buflen))
				return NF_DROP;
		}
	}

next:
	/* Translate Contact headers */
	coff = 0;
	in_header = 0;
	while (ct_sip_parse_header_uri(ct, *dptr, &coff, *datalen,
				       SIP_HDR_CONTACT, &in_header,
				       &matchoff, &matchlen,
				       &addr, &port) > 0) {
		if (!map_addr(skb, dataoff, dptr, datalen, matchoff, matchlen,
			      &addr, port))
			return NF_DROP;
	}

	if (!map_sip_addr(skb, dataoff, dptr, datalen, SIP_HDR_FROM) ||
	    !map_sip_addr(skb, dataoff, dptr, datalen, SIP_HDR_TO))
		return NF_DROP;
	return NF_ACCEPT;
}

/* Handles expected signalling connections and media streams */
static void ip_nat_sip_expected(struct nf_conn *ct,
				struct nf_conntrack_expect *exp)
{
	struct nf_nat_range range;

	/* This must be a fresh one. */
	BUG_ON(ct->status & IPS_NAT_DONE_MASK);

	/* 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 = exp->saved_proto;
	range.min_ip = range.max_ip = exp->saved_ip;
	nf_nat_setup_info(ct, &range, IP_NAT_MANIP_DST);

	/* Change src to where master sends to, but only if the connection
	 * actually came from the same source. */
	if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip ==
	    ct->master->tuplehash[exp->dir].tuple.src.u3.ip) {
		range.flags = IP_NAT_RANGE_MAP_IPS;
		range.min_ip = range.max_ip
			= ct->master->tuplehash[!exp->dir].tuple.dst.u3.ip;
		nf_nat_setup_info(ct, &range, IP_NAT_MANIP_SRC);
	}
}

static unsigned int ip_nat_sip_expect(struct sk_buff *skb, unsigned int dataoff,
				      const char **dptr, unsigned int *datalen,
				      struct nf_conntrack_expect *exp,
				      unsigned int matchoff,
				      unsigned int matchlen)
{
	enum ip_conntrack_info ctinfo;
	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	__be32 newip;
	u_int16_t port;
	char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
	unsigned buflen;

	/* Connection will come from reply */
	if (ct->tuplehash[dir].tuple.src.u3.ip == ct->tuplehash[!dir].tuple.dst.u3.ip)
		newip = exp->tuple.dst.u3.ip;
	else
		newip = ct->tuplehash[!dir].tuple.dst.u3.ip;

	/* If the signalling port matches the connection's source port in the
	 * original direction, try to use the destination port in the opposite
	 * direction. */
	if (exp->tuple.dst.u.udp.port ==
	    ct->tuplehash[dir].tuple.src.u.udp.port)
		port = ntohs(ct->tuplehash[!dir].tuple.dst.u.udp.port);
	else
		port = ntohs(exp->tuple.dst.u.udp.port);

	exp->saved_ip = exp->tuple.dst.u3.ip;
	exp->tuple.dst.u3.ip = newip;
	exp->saved_proto.udp.port = exp->tuple.dst.u.udp.port;
	exp->dir = !dir;
	exp->expectfn = ip_nat_sip_expected;

	for (; port != 0; port++) {
		exp->tuple.dst.u.udp.port = htons(port);
		if (nf_ct_expect_related(exp) == 0)
			break;
	}

	if (port == 0)
		return NF_DROP;

	if (exp->tuple.dst.u3.ip != exp->saved_ip ||
	    exp->tuple.dst.u.udp.port != exp->saved_proto.udp.port) {
		buflen = sprintf(buffer, "%pI4:%u", &newip, port);
		if (!mangle_packet(skb, dataoff, dptr, datalen,
				   matchoff, matchlen, buffer, buflen))
			goto err;
	}
	return NF_ACCEPT;

err:
	nf_ct_unexpect_related(exp);
	return NF_DROP;
}

static int mangle_content_len(struct sk_buff *skb, unsigned int dataoff,
			      const char **dptr, unsigned int *datalen)
{
	enum ip_conntrack_info ctinfo;
	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
	unsigned int matchoff, matchlen;
	char buffer[sizeof("65536")];
	int buflen, c_len;

	/* Get actual SDP length */
	if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen,
				  SDP_HDR_VERSION, SDP_HDR_UNSPEC,
				  &matchoff, &matchlen) <= 0)
		return 0;
	c_len = *datalen - matchoff + strlen("v=");

	/* Now, update SDP length */
	if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CONTENT_LENGTH,
			      &matchoff, &matchlen) <= 0)
		return 0;

	buflen = sprintf(buffer, "%u", c_len);
	return mangle_packet(skb, dataoff, dptr, datalen, matchoff, matchlen,
			     buffer, buflen);
}

static int mangle_sdp_packet(struct sk_buff *skb, unsigned int dataoff,
			     const char **dptr, unsigned int *datalen,
			     unsigned int sdpoff,
			     enum sdp_header_types type,
			     enum sdp_header_types term,
			     char *buffer, int buflen)
{
	enum ip_conntrack_info ctinfo;
	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
	unsigned int matchlen, matchoff;

	if (ct_sip_get_sdp_header(ct, *dptr, sdpoff, *datalen, type, term,
				  &matchoff, &matchlen) <= 0)
		return -ENOENT;
	return mangle_packet(skb, dataoff, dptr, datalen, matchoff, matchlen,
			     buffer, buflen) ? 0 : -EINVAL;
}

static unsigned int ip_nat_sdp_addr(struct sk_buff *skb, unsigned int dataoff,
				    const char **dptr, unsigned int *datalen,
				    unsigned int sdpoff,
				    enum sdp_header_types type,
				    enum sdp_header_types term,
				    const union nf_inet_addr *addr)
{
	char buffer[sizeof("nnn.nnn.nnn.nnn")];
	unsigned int buflen;

	buflen = sprintf(buffer, "%pI4", &addr->ip);
	if (mangle_sdp_packet(skb, dataoff, dptr, datalen, sdpoff, type, term,
			      buffer, buflen))
		return 0;

	return mangle_content_len(skb, dataoff, dptr, datalen);
}

static unsigned int ip_nat_sdp_port(struct sk_buff *skb, unsigned int dataoff,
				    const char **dptr, unsigned int *datalen,
				    unsigned int matchoff,
				    unsigned int matchlen,
				    u_int16_t port)
{
	char buffer[sizeof("nnnnn")];
	unsigned int buflen;

	buflen = sprintf(buffer, "%u", port);
	if (!mangle_packet(skb, dataoff, dptr, datalen, matchoff, matchlen,
			   buffer, buflen))
		return 0;

	return mangle_content_len(skb, dataoff, dptr, datalen);
}

static unsigned int ip_nat_sdp_session(struct sk_buff *skb, unsigned int dataoff,
				       const char **dptr, unsigned int *datalen,
				       unsigned int sdpoff,
				       const union nf_inet_addr *addr)
{
	char buffer[sizeof("nnn.nnn.nnn.nnn")];
	unsigned int buflen;

	/* Mangle session description owner and contact addresses */
	buflen = sprintf(buffer, "%pI4", &addr->ip);
	if (mangle_sdp_packet(skb, dataoff, dptr, datalen, sdpoff,
			       SDP_HDR_OWNER_IP4, SDP_HDR_MEDIA,
			       buffer, buflen))
		return 0;

	switch (mangle_sdp_packet(skb, dataoff, dptr, datalen, sdpoff,
				  SDP_HDR_CONNECTION_IP4, SDP_HDR_MEDIA,
				  buffer, buflen)) {
	case 0:
	/*
	 * RFC 2327:
	 *
	 * Session description
	 *
	 * c=* (connection information - not required if included in all media)
	 */
	case -ENOENT:
		break;
	default:
		return 0;
	}

	return mangle_content_len(skb, dataoff, dptr, datalen);
}

/* So, this packet has hit the connection tracking matching code.
   Mangle it, and change the expectation to match the new version. */
static unsigned int ip_nat_sdp_media(struct sk_buff *skb, unsigned int dataoff,
				     const char **dptr, unsigned int *datalen,
				     struct nf_conntrack_expect *rtp_exp,
				     struct nf_conntrack_expect *rtcp_exp,
				     unsigned int mediaoff,
				     unsigned int medialen,
				     union nf_inet_addr *rtp_addr)
{
	enum ip_conntrack_info ctinfo;
	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	u_int16_t port;

	/* Connection will come from reply */
	if (ct->tuplehash[dir].tuple.src.u3.ip ==
	    ct->tuplehash[!dir].tuple.dst.u3.ip)
		rtp_addr->ip = rtp_exp->tuple.dst.u3.ip;
	else
		rtp_addr->ip = ct->tuplehash[!dir].tuple.dst.u3.ip;

	rtp_exp->saved_ip = rtp_exp->tuple.dst.u3.ip;
	rtp_exp->tuple.dst.u3.ip = rtp_addr->ip;
	rtp_exp->saved_proto.udp.port = rtp_exp->tuple.dst.u.udp.port;
	rtp_exp->dir = !dir;
	rtp_exp->expectfn = ip_nat_sip_expected;

	rtcp_exp->saved_ip = rtcp_exp->tuple.dst.u3.ip;
	rtcp_exp->tuple.dst.u3.ip = rtp_addr->ip;
	rtcp_exp->saved_proto.udp.port = rtcp_exp->tuple.dst.u.udp.port;
	rtcp_exp->dir = !dir;
	rtcp_exp->expectfn = ip_nat_sip_expected;

	/* Try to get same pair of ports: if not, try to change them. */
	for (port = ntohs(rtp_exp->tuple.dst.u.udp.port);
	     port != 0; port += 2) {
		rtp_exp->tuple.dst.u.udp.port = htons(port);
		if (nf_ct_expect_related(rtp_exp) != 0)
			continue;
		rtcp_exp->tuple.dst.u.udp.port = htons(port + 1);
		if (nf_ct_expect_related(rtcp_exp) == 0)
			break;
		nf_ct_unexpect_related(rtp_exp);
	}

	if (port == 0)
		goto err1;

	/* Update media port. */
	if (rtp_exp->tuple.dst.u.udp.port != rtp_exp->saved_proto.udp.port &&
	    !ip_nat_sdp_port(skb, dataoff, dptr, datalen,
			     mediaoff, medialen, port))
		goto err2;

	return NF_ACCEPT;

err2:
	nf_ct_unexpect_related(rtp_exp);
	nf_ct_unexpect_related(rtcp_exp);
err1:
	return NF_DROP;
}

static void __exit nf_nat_sip_fini(void)
{
	rcu_assign_pointer(nf_nat_sip_hook, NULL);
	rcu_assign_pointer(nf_nat_sip_expect_hook, NULL);
	rcu_assign_pointer(nf_nat_sdp_addr_hook, NULL);
	rcu_assign_pointer(nf_nat_sdp_port_hook, NULL);
	rcu_assign_pointer(nf_nat_sdp_session_hook, NULL);
	rcu_assign_pointer(nf_nat_sdp_media_hook, NULL);
	synchronize_rcu();
}

static int __init nf_nat_sip_init(void)
{
	BUG_ON(nf_nat_sip_hook != NULL);
	BUG_ON(nf_nat_sip_expect_hook != NULL);
	BUG_ON(nf_nat_sdp_addr_hook != NULL);
	BUG_ON(nf_nat_sdp_port_hook != NULL);
	BUG_ON(nf_nat_sdp_session_hook != NULL);
	BUG_ON(nf_nat_sdp_media_hook != NULL);
	rcu_assign_pointer(nf_nat_sip_hook, ip_nat_sip);
	rcu_assign_pointer(nf_nat_sip_expect_hook, ip_nat_sip_expect);
	rcu_assign_pointer(nf_nat_sdp_addr_hook, ip_nat_sdp_addr);
	rcu_assign_pointer(nf_nat_sdp_port_hook, ip_nat_sdp_port);
	rcu_assign_pointer(nf_nat_sdp_session_hook, ip_nat_sdp_session);
	rcu_assign_pointer(nf_nat_sdp_media_hook, ip_nat_sdp_media);
	return 0;
}

module_init(nf_nat_sip_init);
module_exit(nf_nat_sip_fini);
Commit	Line	Data
9fafcd7b PM	1	/* SIP extension for UDP NAT alteration.
	2	*
	3	* (C) 2005 by Christian Hentschel <chentschel@arnet.com.ar>
	4	* based on RR's ip_nat_ftp.c and other modules.
f49e1aa1 PM	5	* (C) 2007 United Security Providers
f49e1aa1 PM	6	* (C) 2007, 2008 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>
	15	#include <linux/ip.h>
c9bdd4b5	16	#include <net/ip.h>
9fafcd7b PM	17	#include <linux/udp.h>
	18
	19	#include <net/netfilter/nf_nat.h>
	20	#include <net/netfilter/nf_nat_helper.h>
	21	#include <net/netfilter/nf_nat_rule.h>
	22	#include <net/netfilter/nf_conntrack_helper.h>
	23	#include <net/netfilter/nf_conntrack_expect.h>
	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
3b6b9fab	32	static unsigned int mangle_packet(struct sk_buff *skb, unsigned int dataoff,
2a6cfb22 PM	33	const char *dptr, unsigned int datalen,
	34	unsigned int matchoff, unsigned int matchlen,
	35	const char *buffer, unsigned int buflen)
	36	{
	37	enum ip_conntrack_info ctinfo;
	38	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
	39
	40	if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo, matchoff, matchlen,
	41	buffer, buflen))
	42	return 0;
	43
	44	/* Reload data pointer and adjust datalen value */
3b6b9fab	45	*dptr = skb->data + dataoff;
2a6cfb22 PM	46	*datalen += buflen - matchlen;
	47	return 1;
	48	}
	49
3b6b9fab	50	static int map_addr(struct sk_buff *skb, unsigned int dataoff,
ac367740 PM	51	const char *dptr, unsigned int datalen,
ac367740 PM	52	unsigned int matchoff, unsigned int matchlen,
624f8b7b	53	union nf_inet_addr *addr, __be16 port)
9fafcd7b	54	{
212440a7	55	enum ip_conntrack_info ctinfo;
624f8b7b	56	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
9fafcd7b	57	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
624f8b7b PM	58	char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
	59	unsigned int buflen;
	60	__be32 newaddr;
	61	__be16 newport;
	62
	63	if (ct->tuplehash[dir].tuple.src.u3.ip == addr->ip &&
	64	ct->tuplehash[dir].tuple.src.u.udp.port == port) {
	65	newaddr = ct->tuplehash[!dir].tuple.dst.u3.ip;
	66	newport = ct->tuplehash[!dir].tuple.dst.u.udp.port;
	67	} else if (ct->tuplehash[dir].tuple.dst.u3.ip == addr->ip &&
	68	ct->tuplehash[dir].tuple.dst.u.udp.port == port) {
	69	newaddr = ct->tuplehash[!dir].tuple.src.u3.ip;
	70	newport = ct->tuplehash[!dir].tuple.src.u.udp.port;
9fafcd7b PM	71	} else
	72	return 1;
	73
624f8b7b PM	74	if (newaddr == addr->ip && newport == port)
	75	return 1;
	76
cffee385	77	buflen = sprintf(buffer, "%pI4:%u", &newaddr, ntohs(newport));
624f8b7b	78
3b6b9fab	79	return mangle_packet(skb, dataoff, dptr, datalen, matchoff, matchlen,
624f8b7b	80	buffer, buflen);
9fafcd7b PM	81	}
9fafcd7b PM	82
3b6b9fab	83	static int map_sip_addr(struct sk_buff *skb, unsigned int dataoff,
ac367740	84	const char *dptr, unsigned int datalen,
624f8b7b	85	enum sip_header_types type)
ac367740 PM	86	{
	87	enum ip_conntrack_info ctinfo;
	88	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
	89	unsigned int matchlen, matchoff;
624f8b7b PM	90	union nf_inet_addr addr;
624f8b7b PM	91	__be16 port;
ac367740	92
624f8b7b PM	93	if (ct_sip_parse_header_uri(ct, dptr, NULL, datalen, type, NULL,
624f8b7b PM	94	&matchoff, &matchlen, &addr, &port) <= 0)
ac367740	95	return 1;
3b6b9fab PM	96	return map_addr(skb, dataoff, dptr, datalen, matchoff, matchlen,
3b6b9fab PM	97	&addr, port);
ac367740 PM	98	}
ac367740 PM	99
3b6b9fab	100	static unsigned int ip_nat_sip(struct sk_buff *skb, unsigned int dataoff,
2a6cfb22	101	const char *dptr, unsigned int datalen)
9fafcd7b	102	{
212440a7 PM	103	enum ip_conntrack_info ctinfo;
212440a7 PM	104	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
720ac708	105	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
3b6b9fab	106	unsigned int coff, matchoff, matchlen;
624f8b7b PM	107	union nf_inet_addr addr;
624f8b7b PM	108	__be16 port;
c978cd3a	109	int request, in_header;
9fafcd7b	110
9fafcd7b	111	/* Basic rules: requests and responses. */
779382eb	112	if (strnicmp(*dptr, "SIP/2.0", strlen("SIP/2.0")) != 0) {
ac367740	113	if (ct_sip_parse_request(ct, dptr, datalen,
624f8b7b PM	114	&matchoff, &matchlen,
624f8b7b PM	115	&addr, &port) > 0 &&
3b6b9fab	116	!map_addr(skb, dataoff, dptr, datalen, matchoff, matchlen,
624f8b7b	117	&addr, port))
9fafcd7b	118	return NF_DROP;
720ac708 PM	119	request = 1;
	120	} else
	121	request = 0;
	122
	123	/* Translate topmost Via header and parameters */
	124	if (ct_sip_parse_header_uri(ct, dptr, NULL, datalen,
	125	SIP_HDR_VIA, NULL, &matchoff, &matchlen,
	126	&addr, &port) > 0) {
	127	unsigned int matchend, poff, plen, buflen, n;
	128	char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
	129
	130	/* We're only interested in headers related to this
	131	* connection */
	132	if (request) {
	133	if (addr.ip != ct->tuplehash[dir].tuple.src.u3.ip \|\|
	134	port != ct->tuplehash[dir].tuple.src.u.udp.port)
	135	goto next;
	136	} else {
	137	if (addr.ip != ct->tuplehash[dir].tuple.dst.u3.ip \|\|
	138	port != ct->tuplehash[dir].tuple.dst.u.udp.port)
	139	goto next;
	140	}
	141
3b6b9fab	142	if (!map_addr(skb, dataoff, dptr, datalen, matchoff, matchlen,
720ac708 PM	143	&addr, port))
	144	return NF_DROP;
	145
	146	matchend = matchoff + matchlen;
	147
	148	/* The maddr= parameter (RFC 2361) specifies where to send
	149	* the reply. */
	150	if (ct_sip_parse_address_param(ct, dptr, matchend, datalen,
	151	"maddr=", &poff, &plen,
	152	&addr) > 0 &&
	153	addr.ip == ct->tuplehash[dir].tuple.src.u3.ip &&
	154	addr.ip != ct->tuplehash[!dir].tuple.dst.u3.ip) {
cffee385 HH	155	buflen = sprintf(buffer, "%pI4",
cffee385 HH	156	&ct->tuplehash[!dir].tuple.dst.u3.ip);
3b6b9fab PM	157	if (!mangle_packet(skb, dataoff, dptr, datalen,
3b6b9fab PM	158	poff, plen, buffer, buflen))
720ac708 PM	159	return NF_DROP;
	160	}
	161
	162	/* The received= parameter (RFC 2361) contains the address
	163	* from which the server received the request. */
	164	if (ct_sip_parse_address_param(ct, dptr, matchend, datalen,
	165	"received=", &poff, &plen,
	166	&addr) > 0 &&
	167	addr.ip == ct->tuplehash[dir].tuple.dst.u3.ip &&
	168	addr.ip != ct->tuplehash[!dir].tuple.src.u3.ip) {
cffee385 HH	169	buflen = sprintf(buffer, "%pI4",
cffee385 HH	170	&ct->tuplehash[!dir].tuple.src.u3.ip);
3b6b9fab PM	171	if (!mangle_packet(skb, dataoff, dptr, datalen,
3b6b9fab PM	172	poff, plen, buffer, buflen))
720ac708 PM	173	return NF_DROP;
	174	}
	175
	176	/* The rport= parameter (RFC 3581) contains the port number
	177	* from which the server received the request. */
	178	if (ct_sip_parse_numerical_param(ct, dptr, matchend, datalen,
	179	"rport=", &poff, &plen,
	180	&n) > 0 &&
	181	htons(n) == ct->tuplehash[dir].tuple.dst.u.udp.port &&
	182	htons(n) != ct->tuplehash[!dir].tuple.src.u.udp.port) {
	183	__be16 p = ct->tuplehash[!dir].tuple.src.u.udp.port;
	184	buflen = sprintf(buffer, "%u", ntohs(p));
3b6b9fab PM	185	if (!mangle_packet(skb, dataoff, dptr, datalen,
3b6b9fab PM	186	poff, plen, buffer, buflen))
720ac708 PM	187	return NF_DROP;
720ac708 PM	188	}
9fafcd7b PM	189	}
9fafcd7b PM	190
720ac708	191	next:
c978cd3a	192	/* Translate Contact headers */
3b6b9fab	193	coff = 0;
c978cd3a	194	in_header = 0;
3b6b9fab	195	while (ct_sip_parse_header_uri(ct, dptr, &coff, datalen,
c978cd3a PM	196	SIP_HDR_CONTACT, &in_header,
	197	&matchoff, &matchlen,
	198	&addr, &port) > 0) {
3b6b9fab	199	if (!map_addr(skb, dataoff, dptr, datalen, matchoff, matchlen,
c978cd3a PM	200	&addr, port))
	201	return NF_DROP;
	202	}
	203
3b6b9fab PM	204	if (!map_sip_addr(skb, dataoff, dptr, datalen, SIP_HDR_FROM) \|\|
3b6b9fab PM	205	!map_sip_addr(skb, dataoff, dptr, datalen, SIP_HDR_TO))
9fafcd7b PM	206	return NF_DROP;
	207	return NF_ACCEPT;
	208	}
	209
0f32a40f PM	210	/* Handles expected signalling connections and media streams */
	211	static void ip_nat_sip_expected(struct nf_conn *ct,
	212	struct nf_conntrack_expect *exp)
	213	{
	214	struct nf_nat_range range;
	215
	216	/* This must be a fresh one. */
	217	BUG_ON(ct->status & IPS_NAT_DONE_MASK);
	218
	219	/* For DST manip, map port here to where it's expected. */
	220	range.flags = (IP_NAT_RANGE_MAP_IPS \| IP_NAT_RANGE_PROTO_SPECIFIED);
	221	range.min = range.max = exp->saved_proto;
	222	range.min_ip = range.max_ip = exp->saved_ip;
	223	nf_nat_setup_info(ct, &range, IP_NAT_MANIP_DST);
	224
	225	/* Change src to where master sends to, but only if the connection
	226	* actually came from the same source. */
	227	if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip ==
	228	ct->master->tuplehash[exp->dir].tuple.src.u3.ip) {
	229	range.flags = IP_NAT_RANGE_MAP_IPS;
	230	range.min_ip = range.max_ip
	231	= ct->master->tuplehash[!exp->dir].tuple.dst.u3.ip;
	232	nf_nat_setup_info(ct, &range, IP_NAT_MANIP_SRC);
	233	}
	234	}
	235
3b6b9fab	236	static unsigned int ip_nat_sip_expect(struct sk_buff *skb, unsigned int dataoff,
0f32a40f PM	237	const char *dptr, unsigned int datalen,
	238	struct nf_conntrack_expect *exp,
	239	unsigned int matchoff,
	240	unsigned int matchlen)
	241	{
	242	enum ip_conntrack_info ctinfo;
	243	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
	244	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	245	__be32 newip;
	246	u_int16_t port;
	247	char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
	248	unsigned buflen;
	249
	250	/* Connection will come from reply */
	251	if (ct->tuplehash[dir].tuple.src.u3.ip == ct->tuplehash[!dir].tuple.dst.u3.ip)
	252	newip = exp->tuple.dst.u3.ip;
	253	else
	254	newip = ct->tuplehash[!dir].tuple.dst.u3.ip;
	255
	256	/* If the signalling port matches the connection's source port in the
	257	* original direction, try to use the destination port in the opposite
	258	* direction. */
	259	if (exp->tuple.dst.u.udp.port ==
	260	ct->tuplehash[dir].tuple.src.u.udp.port)
	261	port = ntohs(ct->tuplehash[!dir].tuple.dst.u.udp.port);
	262	else
	263	port = ntohs(exp->tuple.dst.u.udp.port);
	264
	265	exp->saved_ip = exp->tuple.dst.u3.ip;
	266	exp->tuple.dst.u3.ip = newip;
	267	exp->saved_proto.udp.port = exp->tuple.dst.u.udp.port;
	268	exp->dir = !dir;
	269	exp->expectfn = ip_nat_sip_expected;
	270
	271	for (; port != 0; port++) {
	272	exp->tuple.dst.u.udp.port = htons(port);
	273	if (nf_ct_expect_related(exp) == 0)
	274	break;
	275	}
	276
	277	if (port == 0)
	278	return NF_DROP;
	279
	280	if (exp->tuple.dst.u3.ip != exp->saved_ip \|\|
	281	exp->tuple.dst.u.udp.port != exp->saved_proto.udp.port) {
cffee385	282	buflen = sprintf(buffer, "%pI4:%u", &newip, port);
3b6b9fab PM	283	if (!mangle_packet(skb, dataoff, dptr, datalen,
3b6b9fab PM	284	matchoff, matchlen, buffer, buflen))
0f32a40f PM	285	goto err;
	286	}
	287	return NF_ACCEPT;
	288
	289	err:
	290	nf_ct_unexpect_related(exp);
	291	return NF_DROP;
	292	}
	293
3b6b9fab	294	static int mangle_content_len(struct sk_buff *skb, unsigned int dataoff,
3e9b4600	295	const char *dptr, unsigned int datalen)
9fafcd7b	296	{
212440a7 PM	297	enum ip_conntrack_info ctinfo;
212440a7 PM	298	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
3e9b4600 PM	299	unsigned int matchoff, matchlen;
	300	char buffer[sizeof("65536")];
	301	int buflen, c_len;
9fafcd7b	302
3e9b4600 PM	303	/* Get actual SDP length */
	304	if (ct_sip_get_sdp_header(ct, dptr, 0, datalen,
	305	SDP_HDR_VERSION, SDP_HDR_UNSPEC,
	306	&matchoff, &matchlen) <= 0)
	307	return 0;
	308	c_len = *datalen - matchoff + strlen("v=");
	309
	310	/* Now, update SDP length */
ea45f12a PM	311	if (ct_sip_get_header(ct, dptr, 0, datalen, SIP_HDR_CONTENT_LENGTH,
ea45f12a PM	312	&matchoff, &matchlen) <= 0)
9fafcd7b PM	313	return 0;
9fafcd7b PM	314
3e9b4600	315	buflen = sprintf(buffer, "%u", c_len);
3b6b9fab	316	return mangle_packet(skb, dataoff, dptr, datalen, matchoff, matchlen,
3e9b4600	317	buffer, buflen);
9fafcd7b PM	318	}
9fafcd7b PM	319
3b6b9fab PM	320	static int mangle_sdp_packet(struct sk_buff *skb, unsigned int dataoff,
	321	const char *dptr, unsigned int datalen,
	322	unsigned int sdpoff,
c71529e4 HX	323	enum sdp_header_types type,
	324	enum sdp_header_types term,
	325	char *buffer, int buflen)
9fafcd7b	326	{
212440a7 PM	327	enum ip_conntrack_info ctinfo;
212440a7 PM	328	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
3e9b4600	329	unsigned int matchlen, matchoff;
9fafcd7b	330
3b6b9fab	331	if (ct_sip_get_sdp_header(ct, dptr, sdpoff, datalen, type, term,
3e9b4600	332	&matchoff, &matchlen) <= 0)
c71529e4	333	return -ENOENT;
3b6b9fab	334	return mangle_packet(skb, dataoff, dptr, datalen, matchoff, matchlen,
c71529e4	335	buffer, buflen) ? 0 : -EINVAL;
9fafcd7b PM	336	}
9fafcd7b PM	337
3b6b9fab PM	338	static unsigned int ip_nat_sdp_addr(struct sk_buff *skb, unsigned int dataoff,
	339	const char *dptr, unsigned int datalen,
	340	unsigned int sdpoff,
4ab9e64e PM	341	enum sdp_header_types type,
	342	enum sdp_header_types term,
	343	const union nf_inet_addr *addr)
9fafcd7b PM	344	{
9fafcd7b PM	345	char buffer[sizeof("nnn.nnn.nnn.nnn")];
4ab9e64e	346	unsigned int buflen;
9fafcd7b	347
cffee385	348	buflen = sprintf(buffer, "%pI4", &addr->ip);
3b6b9fab	349	if (mangle_sdp_packet(skb, dataoff, dptr, datalen, sdpoff, type, term,
c71529e4	350	buffer, buflen))
9fafcd7b PM	351	return 0;
9fafcd7b PM	352
3b6b9fab	353	return mangle_content_len(skb, dataoff, dptr, datalen);
4ab9e64e PM	354	}
4ab9e64e PM	355
3b6b9fab PM	356	static unsigned int ip_nat_sdp_port(struct sk_buff *skb, unsigned int dataoff,
3b6b9fab PM	357	const char *dptr, unsigned int datalen,
4ab9e64e PM	358	unsigned int matchoff,
	359	unsigned int matchlen,
	360	u_int16_t port)
	361	{
	362	char buffer[sizeof("nnnnn")];
	363	unsigned int buflen;
	364
	365	buflen = sprintf(buffer, "%u", port);
3b6b9fab	366	if (!mangle_packet(skb, dataoff, dptr, datalen, matchoff, matchlen,
4ab9e64e	367	buffer, buflen))
9fafcd7b PM	368	return 0;
9fafcd7b PM	369
3b6b9fab	370	return mangle_content_len(skb, dataoff, dptr, datalen);
4ab9e64e PM	371	}
4ab9e64e PM	372
3b6b9fab PM	373	static unsigned int ip_nat_sdp_session(struct sk_buff *skb, unsigned int dataoff,
	374	const char *dptr, unsigned int datalen,
	375	unsigned int sdpoff,
4ab9e64e PM	376	const union nf_inet_addr *addr)
	377	{
	378	char buffer[sizeof("nnn.nnn.nnn.nnn")];
	379	unsigned int buflen;
	380
	381	/* Mangle session description owner and contact addresses */
cffee385	382	buflen = sprintf(buffer, "%pI4", &addr->ip);
3b6b9fab	383	if (mangle_sdp_packet(skb, dataoff, dptr, datalen, sdpoff,
4ab9e64e PM	384	SDP_HDR_OWNER_IP4, SDP_HDR_MEDIA,
	385	buffer, buflen))
	386	return 0;
	387
3b6b9fab	388	switch (mangle_sdp_packet(skb, dataoff, dptr, datalen, sdpoff,
c71529e4 HX	389	SDP_HDR_CONNECTION_IP4, SDP_HDR_MEDIA,
	390	buffer, buflen)) {
	391	case 0:
	392	/*
	393	* RFC 2327:
	394	*
	395	* Session description
	396	*
	397	* c=* (connection information - not required if included in all media)
	398	*/
	399	case -ENOENT:
	400	break;
	401	default:
9fafcd7b	402	return 0;
c71529e4	403	}
9fafcd7b	404
3b6b9fab	405	return mangle_content_len(skb, dataoff, dptr, datalen);
9fafcd7b PM	406	}
	407
	408	/* So, this packet has hit the connection tracking matching code.
	409	Mangle it, and change the expectation to match the new version. */
3b6b9fab PM	410	static unsigned int ip_nat_sdp_media(struct sk_buff *skb, unsigned int dataoff,
3b6b9fab PM	411	const char *dptr, unsigned int datalen,
4ab9e64e PM	412	struct nf_conntrack_expect *rtp_exp,
	413	struct nf_conntrack_expect *rtcp_exp,
	414	unsigned int mediaoff,
	415	unsigned int medialen,
	416	union nf_inet_addr *rtp_addr)
9fafcd7b	417	{
212440a7 PM	418	enum ip_conntrack_info ctinfo;
212440a7 PM	419	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
9fafcd7b	420	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
9fafcd7b PM	421	u_int16_t port;
9fafcd7b PM	422
9fafcd7b	423	/* Connection will come from reply */
f4a607bf JB	424	if (ct->tuplehash[dir].tuple.src.u3.ip ==
f4a607bf JB	425	ct->tuplehash[!dir].tuple.dst.u3.ip)
4ab9e64e	426	rtp_addr->ip = rtp_exp->tuple.dst.u3.ip;
f4a607bf	427	else
4ab9e64e	428	rtp_addr->ip = ct->tuplehash[!dir].tuple.dst.u3.ip;
9fafcd7b	429
a9c1d359	430	rtp_exp->saved_ip = rtp_exp->tuple.dst.u3.ip;
4ab9e64e	431	rtp_exp->tuple.dst.u3.ip = rtp_addr->ip;
a9c1d359 PM	432	rtp_exp->saved_proto.udp.port = rtp_exp->tuple.dst.u.udp.port;
	433	rtp_exp->dir = !dir;
	434	rtp_exp->expectfn = ip_nat_sip_expected;
	435
	436	rtcp_exp->saved_ip = rtcp_exp->tuple.dst.u3.ip;
4ab9e64e	437	rtcp_exp->tuple.dst.u3.ip = rtp_addr->ip;
a9c1d359 PM	438	rtcp_exp->saved_proto.udp.port = rtcp_exp->tuple.dst.u.udp.port;
	439	rtcp_exp->dir = !dir;
	440	rtcp_exp->expectfn = ip_nat_sip_expected;
	441
	442	/* Try to get same pair of ports: if not, try to change them. */
	443	for (port = ntohs(rtp_exp->tuple.dst.u.udp.port);
	444	port != 0; port += 2) {
	445	rtp_exp->tuple.dst.u.udp.port = htons(port);
	446	if (nf_ct_expect_related(rtp_exp) != 0)
	447	continue;
	448	rtcp_exp->tuple.dst.u.udp.port = htons(port + 1);
	449	if (nf_ct_expect_related(rtcp_exp) == 0)
9fafcd7b	450	break;
a9c1d359	451	nf_ct_unexpect_related(rtp_exp);
9fafcd7b PM	452	}
	453
	454	if (port == 0)
4ab9e64e PM	455	goto err1;
	456
	457	/* Update media port. */
	458	if (rtp_exp->tuple.dst.u.udp.port != rtp_exp->saved_proto.udp.port &&
3b6b9fab PM	459	!ip_nat_sdp_port(skb, dataoff, dptr, datalen,
3b6b9fab PM	460	mediaoff, medialen, port))
4ab9e64e	461	goto err2;
9fafcd7b	462
9fafcd7b	463	return NF_ACCEPT;
4ab9e64e PM	464
	465	err2:
	466	nf_ct_unexpect_related(rtp_exp);
	467	nf_ct_unexpect_related(rtcp_exp);
	468	err1:
	469	return NF_DROP;
9fafcd7b PM	470	}
	471
	472	static void __exit nf_nat_sip_fini(void)
	473	{
	474	rcu_assign_pointer(nf_nat_sip_hook, NULL);
0f32a40f	475	rcu_assign_pointer(nf_nat_sip_expect_hook, NULL);
4ab9e64e	476	rcu_assign_pointer(nf_nat_sdp_addr_hook, NULL);
c7f485ab	477	rcu_assign_pointer(nf_nat_sdp_port_hook, NULL);
4ab9e64e PM	478	rcu_assign_pointer(nf_nat_sdp_session_hook, NULL);
4ab9e64e PM	479	rcu_assign_pointer(nf_nat_sdp_media_hook, NULL);
9fafcd7b PM	480	synchronize_rcu();
	481	}
	482
	483	static int __init nf_nat_sip_init(void)
	484	{
d1332e0a	485	BUG_ON(nf_nat_sip_hook != NULL);
0f32a40f	486	BUG_ON(nf_nat_sip_expect_hook != NULL);
4ab9e64e	487	BUG_ON(nf_nat_sdp_addr_hook != NULL);
c7f485ab	488	BUG_ON(nf_nat_sdp_port_hook != NULL);
4ab9e64e PM	489	BUG_ON(nf_nat_sdp_session_hook != NULL);
4ab9e64e PM	490	BUG_ON(nf_nat_sdp_media_hook != NULL);
9fafcd7b	491	rcu_assign_pointer(nf_nat_sip_hook, ip_nat_sip);
0f32a40f	492	rcu_assign_pointer(nf_nat_sip_expect_hook, ip_nat_sip_expect);
4ab9e64e	493	rcu_assign_pointer(nf_nat_sdp_addr_hook, ip_nat_sdp_addr);
c7f485ab	494	rcu_assign_pointer(nf_nat_sdp_port_hook, ip_nat_sdp_port);
4ab9e64e PM	495	rcu_assign_pointer(nf_nat_sdp_session_hook, ip_nat_sdp_session);
4ab9e64e PM	496	rcu_assign_pointer(nf_nat_sdp_media_hook, ip_nat_sdp_media);
9fafcd7b PM	497	return 0;
	498	}
	499
	500	module_init(nf_nat_sip_init);
	501	module_exit(nf_nat_sip_fini);