[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,
				  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 + ip_hdrlen(skb) + sizeof(struct udphdr);
	*datalen += buflen - matchlen;
	return 1;
}

static int map_addr(struct sk_buff *skb,
		    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, dptr, datalen, matchoff, matchlen,
			     buffer, buflen);
}

static int map_sip_addr(struct sk_buff *skb,
			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, dptr, datalen, matchoff, matchlen, &addr, port);
}

static unsigned int ip_nat_sip(struct sk_buff *skb,
			       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 dataoff, 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, 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, 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, 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, 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, dptr, datalen, poff, plen,
					   buffer, buflen))
				return NF_DROP;
		}
	}

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

	if (!map_sip_addr(skb, dptr, datalen, SIP_HDR_FROM) ||
	    !map_sip_addr(skb, 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,
				      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, 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,
			      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, dptr, datalen, matchoff, matchlen,
			     buffer, buflen);
}

static int mangle_sdp_packet(struct sk_buff *skb, const char **dptr,
			     unsigned int dataoff, unsigned int *datalen,
			     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, dataoff, *datalen, type, term,
				  &matchoff, &matchlen) <= 0)
		return -ENOENT;
	return mangle_packet(skb, dptr, datalen, matchoff, matchlen,
			     buffer, buflen) ? 0 : -EINVAL;
}

static unsigned int ip_nat_sdp_addr(struct sk_buff *skb, const char **dptr,
				    unsigned int dataoff,
				    unsigned int *datalen,
				    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, dptr, dataoff, datalen, type, term,
			      buffer, buflen))
		return 0;

	return mangle_content_len(skb, dptr, datalen);
}

static unsigned int ip_nat_sdp_port(struct sk_buff *skb,
				    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, dptr, datalen, matchoff, matchlen,
			   buffer, buflen))
		return 0;

	return mangle_content_len(skb, dptr, datalen);
}

static unsigned int ip_nat_sdp_session(struct sk_buff *skb, const char **dptr,
				       unsigned int dataoff,
				       unsigned int *datalen,
				       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, dptr, dataoff, datalen,
			       SDP_HDR_OWNER_IP4, SDP_HDR_MEDIA,
			       buffer, buflen))
		return 0;

	switch (mangle_sdp_packet(skb, dptr, dataoff, datalen,
				  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, 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,
				     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, 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
2a6cfb22 PM	32	static unsigned int mangle_packet(struct sk_buff *skb,
	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 */
	45	*dptr = skb->data + ip_hdrlen(skb) + sizeof(struct udphdr);
	46	*datalen += buflen - matchlen;
	47	return 1;
	48	}
	49
ac367740 PM	50	static int map_addr(struct sk_buff *skb,
	51	const char *dptr, unsigned int datalen,
	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
2a6cfb22	79	return mangle_packet(skb, dptr, datalen, matchoff, matchlen,
624f8b7b	80	buffer, buflen);
9fafcd7b PM	81	}
9fafcd7b PM	82
ac367740 PM	83	static int map_sip_addr(struct sk_buff *skb,
ac367740 PM	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;
624f8b7b	96	return map_addr(skb, dptr, datalen, matchoff, matchlen, &addr, port);
ac367740 PM	97	}
ac367740 PM	98
3db05fea	99	static unsigned int ip_nat_sip(struct sk_buff *skb,
2a6cfb22	100	const char *dptr, unsigned int datalen)
9fafcd7b	101	{
212440a7 PM	102	enum ip_conntrack_info ctinfo;
212440a7 PM	103	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
720ac708	104	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
c978cd3a	105	unsigned int dataoff, matchoff, matchlen;
624f8b7b PM	106	union nf_inet_addr addr;
624f8b7b PM	107	__be16 port;
c978cd3a	108	int request, in_header;
9fafcd7b	109
9fafcd7b	110	/* Basic rules: requests and responses. */
779382eb	111	if (strnicmp(*dptr, "SIP/2.0", strlen("SIP/2.0")) != 0) {
ac367740	112	if (ct_sip_parse_request(ct, dptr, datalen,
624f8b7b PM	113	&matchoff, &matchlen,
	114	&addr, &port) > 0 &&
	115	!map_addr(skb, dptr, datalen, matchoff, matchlen,
	116	&addr, port))
9fafcd7b	117	return NF_DROP;
720ac708 PM	118	request = 1;
	119	} else
	120	request = 0;
	121
	122	/* Translate topmost Via header and parameters */
	123	if (ct_sip_parse_header_uri(ct, dptr, NULL, datalen,
	124	SIP_HDR_VIA, NULL, &matchoff, &matchlen,
	125	&addr, &port) > 0) {
	126	unsigned int matchend, poff, plen, buflen, n;
	127	char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
	128
	129	/* We're only interested in headers related to this
	130	* connection */
	131	if (request) {
	132	if (addr.ip != ct->tuplehash[dir].tuple.src.u3.ip \|\|
	133	port != ct->tuplehash[dir].tuple.src.u.udp.port)
	134	goto next;
	135	} else {
	136	if (addr.ip != ct->tuplehash[dir].tuple.dst.u3.ip \|\|
	137	port != ct->tuplehash[dir].tuple.dst.u.udp.port)
	138	goto next;
	139	}
	140
	141	if (!map_addr(skb, dptr, datalen, matchoff, matchlen,
	142	&addr, port))
	143	return NF_DROP;
	144
	145	matchend = matchoff + matchlen;
	146
	147	/* The maddr= parameter (RFC 2361) specifies where to send
	148	* the reply. */
	149	if (ct_sip_parse_address_param(ct, dptr, matchend, datalen,
	150	"maddr=", &poff, &plen,
	151	&addr) > 0 &&
	152	addr.ip == ct->tuplehash[dir].tuple.src.u3.ip &&
	153	addr.ip != ct->tuplehash[!dir].tuple.dst.u3.ip) {
cffee385 HH	154	buflen = sprintf(buffer, "%pI4",
cffee385 HH	155	&ct->tuplehash[!dir].tuple.dst.u3.ip);
720ac708 PM	156	if (!mangle_packet(skb, dptr, datalen, poff, plen,
	157	buffer, buflen))
	158	return NF_DROP;
	159	}
	160
	161	/* The received= parameter (RFC 2361) contains the address
	162	* from which the server received the request. */
	163	if (ct_sip_parse_address_param(ct, dptr, matchend, datalen,
	164	"received=", &poff, &plen,
	165	&addr) > 0 &&
	166	addr.ip == ct->tuplehash[dir].tuple.dst.u3.ip &&
	167	addr.ip != ct->tuplehash[!dir].tuple.src.u3.ip) {
cffee385 HH	168	buflen = sprintf(buffer, "%pI4",
cffee385 HH	169	&ct->tuplehash[!dir].tuple.src.u3.ip);
720ac708 PM	170	if (!mangle_packet(skb, dptr, datalen, poff, plen,
	171	buffer, buflen))
	172	return NF_DROP;
	173	}
	174
	175	/* The rport= parameter (RFC 3581) contains the port number
	176	* from which the server received the request. */
	177	if (ct_sip_parse_numerical_param(ct, dptr, matchend, datalen,
	178	"rport=", &poff, &plen,
	179	&n) > 0 &&
	180	htons(n) == ct->tuplehash[dir].tuple.dst.u.udp.port &&
	181	htons(n) != ct->tuplehash[!dir].tuple.src.u.udp.port) {
	182	__be16 p = ct->tuplehash[!dir].tuple.src.u.udp.port;
	183	buflen = sprintf(buffer, "%u", ntohs(p));
	184	if (!mangle_packet(skb, dptr, datalen, poff, plen,
	185	buffer, buflen))
	186	return NF_DROP;
	187	}
9fafcd7b PM	188	}
9fafcd7b PM	189
720ac708	190	next:
c978cd3a PM	191	/* Translate Contact headers */
	192	dataoff = 0;
	193	in_header = 0;
	194	while (ct_sip_parse_header_uri(ct, dptr, &dataoff, datalen,
	195	SIP_HDR_CONTACT, &in_header,
	196	&matchoff, &matchlen,
	197	&addr, &port) > 0) {
	198	if (!map_addr(skb, dptr, datalen, matchoff, matchlen,
	199	&addr, port))
	200	return NF_DROP;
	201	}
	202
624f8b7b	203	if (!map_sip_addr(skb, dptr, datalen, SIP_HDR_FROM) \|\|
c978cd3a	204	!map_sip_addr(skb, dptr, datalen, SIP_HDR_TO))
9fafcd7b PM	205	return NF_DROP;
	206	return NF_ACCEPT;
	207	}
	208
0f32a40f PM	209	/* Handles expected signalling connections and media streams */
	210	static void ip_nat_sip_expected(struct nf_conn *ct,
	211	struct nf_conntrack_expect *exp)
	212	{
	213	struct nf_nat_range range;
	214
	215	/* This must be a fresh one. */
	216	BUG_ON(ct->status & IPS_NAT_DONE_MASK);
	217
	218	/* For DST manip, map port here to where it's expected. */
	219	range.flags = (IP_NAT_RANGE_MAP_IPS \| IP_NAT_RANGE_PROTO_SPECIFIED);
	220	range.min = range.max = exp->saved_proto;
	221	range.min_ip = range.max_ip = exp->saved_ip;
	222	nf_nat_setup_info(ct, &range, IP_NAT_MANIP_DST);
	223
	224	/* Change src to where master sends to, but only if the connection
	225	* actually came from the same source. */
	226	if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip ==
	227	ct->master->tuplehash[exp->dir].tuple.src.u3.ip) {
	228	range.flags = IP_NAT_RANGE_MAP_IPS;
	229	range.min_ip = range.max_ip
	230	= ct->master->tuplehash[!exp->dir].tuple.dst.u3.ip;
	231	nf_nat_setup_info(ct, &range, IP_NAT_MANIP_SRC);
	232	}
	233	}
	234
	235	static unsigned int ip_nat_sip_expect(struct sk_buff *skb,
	236	const char *dptr, unsigned int datalen,
	237	struct nf_conntrack_expect *exp,
	238	unsigned int matchoff,
	239	unsigned int matchlen)
	240	{
	241	enum ip_conntrack_info ctinfo;
	242	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
	243	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	244	__be32 newip;
	245	u_int16_t port;
	246	char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
	247	unsigned buflen;
	248
	249	/* Connection will come from reply */
	250	if (ct->tuplehash[dir].tuple.src.u3.ip == ct->tuplehash[!dir].tuple.dst.u3.ip)
	251	newip = exp->tuple.dst.u3.ip;
	252	else
	253	newip = ct->tuplehash[!dir].tuple.dst.u3.ip;
	254
	255	/* If the signalling port matches the connection's source port in the
	256	* original direction, try to use the destination port in the opposite
	257	* direction. */
	258	if (exp->tuple.dst.u.udp.port ==
	259	ct->tuplehash[dir].tuple.src.u.udp.port)
	260	port = ntohs(ct->tuplehash[!dir].tuple.dst.u.udp.port);
	261	else
	262	port = ntohs(exp->tuple.dst.u.udp.port);
	263
	264	exp->saved_ip = exp->tuple.dst.u3.ip;
	265	exp->tuple.dst.u3.ip = newip;
	266	exp->saved_proto.udp.port = exp->tuple.dst.u.udp.port;
	267	exp->dir = !dir;
	268	exp->expectfn = ip_nat_sip_expected;
	269
	270	for (; port != 0; port++) {
	271	exp->tuple.dst.u.udp.port = htons(port);
	272	if (nf_ct_expect_related(exp) == 0)
273	break;
274	}
275
276	if (port == 0)
277	return NF_DROP;
278
279	if (exp->tuple.dst.u3.ip != exp->saved_ip \|\|
280	exp->tuple.dst.u.udp.port != exp->saved_proto.udp.port) {
cffee385	281	buflen = sprintf(buffer, "%pI4:%u", &newip, port);
0f32a40f PM	282	if (!mangle_packet(skb, dptr, datalen, matchoff, matchlen,
	283	buffer, buflen))
	284	goto err;
	285	}
	286	return NF_ACCEPT;
	287
	288	err:
	289	nf_ct_unexpect_related(exp);
	290	return NF_DROP;
	291	}
	292
3e9b4600 PM	293	static int mangle_content_len(struct sk_buff *skb,
3e9b4600 PM	294	const char *dptr, unsigned int datalen)
9fafcd7b	295	{
212440a7 PM	296	enum ip_conntrack_info ctinfo;
212440a7 PM	297	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
3e9b4600 PM	298	unsigned int matchoff, matchlen;
	299	char buffer[sizeof("65536")];
	300	int buflen, c_len;
9fafcd7b	301
3e9b4600 PM	302	/* Get actual SDP length */
	303	if (ct_sip_get_sdp_header(ct, dptr, 0, datalen,
	304	SDP_HDR_VERSION, SDP_HDR_UNSPEC,
	305	&matchoff, &matchlen) <= 0)
	306	return 0;
	307	c_len = *datalen - matchoff + strlen("v=");
	308
	309	/* Now, update SDP length */
ea45f12a PM	310	if (ct_sip_get_header(ct, dptr, 0, datalen, SIP_HDR_CONTENT_LENGTH,
ea45f12a PM	311	&matchoff, &matchlen) <= 0)
9fafcd7b PM	312	return 0;
9fafcd7b PM	313
3e9b4600	314	buflen = sprintf(buffer, "%u", c_len);
2a6cfb22	315	return mangle_packet(skb, dptr, datalen, matchoff, matchlen,
3e9b4600	316	buffer, buflen);
9fafcd7b PM	317	}
9fafcd7b PM	318
c71529e4 HX	319	static int mangle_sdp_packet(struct sk_buff skb, const char *dptr,
	320	unsigned int dataoff, unsigned int *datalen,
	321	enum sdp_header_types type,
	322	enum sdp_header_types term,
	323	char *buffer, int buflen)
9fafcd7b	324	{
212440a7 PM	325	enum ip_conntrack_info ctinfo;
212440a7 PM	326	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
3e9b4600	327	unsigned int matchlen, matchoff;
9fafcd7b	328
4ab9e64e	329	if (ct_sip_get_sdp_header(ct, dptr, dataoff, datalen, type, term,
3e9b4600	330	&matchoff, &matchlen) <= 0)
c71529e4	331	return -ENOENT;
3e9b4600	332	return mangle_packet(skb, dptr, datalen, matchoff, matchlen,
c71529e4	333	buffer, buflen) ? 0 : -EINVAL;
9fafcd7b PM	334	}
9fafcd7b PM	335
4ab9e64e PM	336	static unsigned int ip_nat_sdp_addr(struct sk_buff skb, const char *dptr,
	337	unsigned int dataoff,
	338	unsigned int *datalen,
	339	enum sdp_header_types type,
	340	enum sdp_header_types term,
	341	const union nf_inet_addr *addr)
9fafcd7b PM	342	{
9fafcd7b PM	343	char buffer[sizeof("nnn.nnn.nnn.nnn")];
4ab9e64e	344	unsigned int buflen;
9fafcd7b	345
cffee385	346	buflen = sprintf(buffer, "%pI4", &addr->ip);
c71529e4 HX	347	if (mangle_sdp_packet(skb, dptr, dataoff, datalen, type, term,
c71529e4 HX	348	buffer, buflen))
9fafcd7b PM	349	return 0;
9fafcd7b PM	350
4ab9e64e PM	351	return mangle_content_len(skb, dptr, datalen);
	352	}
	353
	354	static unsigned int ip_nat_sdp_port(struct sk_buff *skb,
	355	const char **dptr,
	356	unsigned int *datalen,
	357	unsigned int matchoff,
	358	unsigned int matchlen,
	359	u_int16_t port)
	360	{
	361	char buffer[sizeof("nnnnn")];
	362	unsigned int buflen;
	363
	364	buflen = sprintf(buffer, "%u", port);
	365	if (!mangle_packet(skb, dptr, datalen, matchoff, matchlen,
	366	buffer, buflen))
9fafcd7b PM	367	return 0;
9fafcd7b PM	368
4ab9e64e PM	369	return mangle_content_len(skb, dptr, datalen);
	370	}
	371
	372	static unsigned int ip_nat_sdp_session(struct sk_buff skb, const char *dptr,
	373	unsigned int dataoff,
	374	unsigned int *datalen,
	375	const union nf_inet_addr *addr)
	376	{
	377	char buffer[sizeof("nnn.nnn.nnn.nnn")];
	378	unsigned int buflen;
	379
	380	/* Mangle session description owner and contact addresses */
cffee385	381	buflen = sprintf(buffer, "%pI4", &addr->ip);
c71529e4	382	if (mangle_sdp_packet(skb, dptr, dataoff, datalen,
4ab9e64e PM	383	SDP_HDR_OWNER_IP4, SDP_HDR_MEDIA,
	384	buffer, buflen))
	385	return 0;
	386
c71529e4 HX	387	switch (mangle_sdp_packet(skb, dptr, dataoff, datalen,
	388	SDP_HDR_CONNECTION_IP4, SDP_HDR_MEDIA,
	389	buffer, buflen)) {
	390	case 0:
	391	/*
	392	* RFC 2327:
	393	*
	394	* Session description
	395	*
	396	* c=* (connection information - not required if included in all media)
	397	*/
	398	case -ENOENT:
	399	break;
	400	default:
9fafcd7b	401	return 0;
c71529e4	402	}
9fafcd7b	403
212440a7	404	return mangle_content_len(skb, dptr, datalen);
9fafcd7b PM	405	}
	406
	407	/* So, this packet has hit the connection tracking matching code.
	408	Mangle it, and change the expectation to match the new version. */
4ab9e64e PM	409	static unsigned int ip_nat_sdp_media(struct sk_buff *skb,
	410	const char **dptr,
	411	unsigned int *datalen,
	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 &&
	459	!ip_nat_sdp_port(skb, dptr, datalen, mediaoff, medialen, port))
	460	goto err2;
9fafcd7b	461
9fafcd7b	462	return NF_ACCEPT;
4ab9e64e PM	463
	464	err2:
	465	nf_ct_unexpect_related(rtp_exp);
	466	nf_ct_unexpect_related(rtcp_exp);
	467	err1:
	468	return NF_DROP;
9fafcd7b PM	469	}
	470
	471	static void __exit nf_nat_sip_fini(void)
	472	{
	473	rcu_assign_pointer(nf_nat_sip_hook, NULL);
0f32a40f	474	rcu_assign_pointer(nf_nat_sip_expect_hook, NULL);
4ab9e64e	475	rcu_assign_pointer(nf_nat_sdp_addr_hook, NULL);
c7f485ab	476	rcu_assign_pointer(nf_nat_sdp_port_hook, NULL);
4ab9e64e PM	477	rcu_assign_pointer(nf_nat_sdp_session_hook, NULL);
4ab9e64e PM	478	rcu_assign_pointer(nf_nat_sdp_media_hook, NULL);
9fafcd7b PM	479	synchronize_rcu();
	480	}
	481
	482	static int __init nf_nat_sip_init(void)
	483	{
d1332e0a	484	BUG_ON(nf_nat_sip_hook != NULL);
0f32a40f	485	BUG_ON(nf_nat_sip_expect_hook != NULL);
4ab9e64e	486	BUG_ON(nf_nat_sdp_addr_hook != NULL);
c7f485ab	487	BUG_ON(nf_nat_sdp_port_hook != NULL);
4ab9e64e PM	488	BUG_ON(nf_nat_sdp_session_hook != NULL);
4ab9e64e PM	489	BUG_ON(nf_nat_sdp_media_hook != NULL);
9fafcd7b	490	rcu_assign_pointer(nf_nat_sip_hook, ip_nat_sip);
0f32a40f	491	rcu_assign_pointer(nf_nat_sip_expect_hook, ip_nat_sip_expect);
4ab9e64e	492	rcu_assign_pointer(nf_nat_sdp_addr_hook, ip_nat_sdp_addr);
c7f485ab	493	rcu_assign_pointer(nf_nat_sdp_port_hook, ip_nat_sdp_port);
4ab9e64e PM	494	rcu_assign_pointer(nf_nat_sdp_session_hook, ip_nat_sdp_session);
4ab9e64e PM	495	rcu_assign_pointer(nf_nat_sdp_media_hook, ip_nat_sdp_media);
9fafcd7b PM	496	return 0;
	497	}
	498
	499	module_init(nf_nat_sip_init);
	500	module_exit(nf_nat_sip_fini);