[linux-block.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, "%u.%u.%u.%u:%u",
			 NIPQUAD(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) {
			__be32 ip = ct->tuplehash[!dir].tuple.dst.u3.ip;
			buflen = sprintf(buffer, "%u.%u.%u.%u", NIPQUAD(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) {
			__be32 ip = ct->tuplehash[!dir].tuple.src.u3.ip;
			buflen = sprintf(buffer, "%u.%u.%u.%u", NIPQUAD(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, "%u.%u.%u.%u:%u",
				 NIPQUAD(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 unsigned 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 0;
	return mangle_packet(skb, dptr, datalen, matchoff, matchlen,
			     buffer, buflen);
}

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, NIPQUAD_FMT, NIPQUAD(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, "%u.%u.%u.%u", NIPQUAD(addr->ip));
	if (!mangle_sdp_packet(skb, dptr, dataoff, datalen,
			       SDP_HDR_OWNER_IP4, SDP_HDR_MEDIA,
			       buffer, buflen))
		return 0;

	if (!mangle_sdp_packet(skb, dptr, dataoff, datalen,
			       SDP_HDR_CONNECTION_IP4, SDP_HDR_MEDIA,
			       buffer, buflen))
		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
	77	buflen = sprintf(buffer, "%u.%u.%u.%u:%u",
	78	NIPQUAD(newaddr), ntohs(newport));
	79
2a6cfb22	80	return mangle_packet(skb, dptr, datalen, matchoff, matchlen,
624f8b7b	81	buffer, buflen);
9fafcd7b PM	82	}
9fafcd7b PM	83
ac367740 PM	84	static int map_sip_addr(struct sk_buff *skb,
ac367740 PM	85	const char *dptr, unsigned int datalen,
624f8b7b	86	enum sip_header_types type)
ac367740 PM	87	{
	88	enum ip_conntrack_info ctinfo;
	89	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
	90	unsigned int matchlen, matchoff;
624f8b7b PM	91	union nf_inet_addr addr;
624f8b7b PM	92	__be16 port;
ac367740	93
624f8b7b PM	94	if (ct_sip_parse_header_uri(ct, dptr, NULL, datalen, type, NULL,
624f8b7b PM	95	&matchoff, &matchlen, &addr, &port) <= 0)
ac367740	96	return 1;
624f8b7b	97	return map_addr(skb, dptr, datalen, matchoff, matchlen, &addr, port);
ac367740 PM	98	}
ac367740 PM	99
3db05fea	100	static unsigned int ip_nat_sip(struct sk_buff *skb,
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);
c978cd3a	106	unsigned int dataoff, 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,
	115	&addr, &port) > 0 &&
	116	!map_addr(skb, dptr, datalen, matchoff, matchlen,
	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
	142	if (!map_addr(skb, dptr, datalen, matchoff, matchlen,
	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) {
	155	__be32 ip = ct->tuplehash[!dir].tuple.dst.u3.ip;
	156	buflen = sprintf(buffer, "%u.%u.%u.%u", NIPQUAD(ip));
	157	if (!mangle_packet(skb, dptr, datalen, poff, plen,
	158	buffer, buflen))
	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) {
	169	__be32 ip = ct->tuplehash[!dir].tuple.src.u3.ip;
	170	buflen = sprintf(buffer, "%u.%u.%u.%u", NIPQUAD(ip));
	171	if (!mangle_packet(skb, dptr, datalen, poff, plen,
	172	buffer, buflen))
	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));
185	if (!mangle_packet(skb, dptr, datalen, poff, plen,
186	buffer, buflen))
187	return NF_DROP;
188	}
9fafcd7b PM	189	}
9fafcd7b PM	190
720ac708	191	next:
c978cd3a PM	192	/* Translate Contact headers */
	193	dataoff = 0;
	194	in_header = 0;
	195	while (ct_sip_parse_header_uri(ct, dptr, &dataoff, datalen,
	196	SIP_HDR_CONTACT, &in_header,
	197	&matchoff, &matchlen,
	198	&addr, &port) > 0) {
	199	if (!map_addr(skb, dptr, datalen, matchoff, matchlen,
	200	&addr, port))
	201	return NF_DROP;
	202	}
	203
624f8b7b	204	if (!map_sip_addr(skb, dptr, datalen, SIP_HDR_FROM) \|\|
c978cd3a	205	!map_sip_addr(skb, 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
	236	static unsigned int ip_nat_sip_expect(struct sk_buff *skb,
	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) {
282	buflen = sprintf(buffer, "%u.%u.%u.%u:%u",
283	NIPQUAD(newip), port);
284	if (!mangle_packet(skb, dptr, datalen, matchoff, matchlen,
285	buffer, buflen))
286	goto err;
287	}
288	return NF_ACCEPT;
289
290	err:
291	nf_ct_unexpect_related(exp);
292	return NF_DROP;
293	}
294
3e9b4600 PM	295	static int mangle_content_len(struct sk_buff *skb,
3e9b4600 PM	296	const char *dptr, unsigned int datalen)
9fafcd7b	297	{
212440a7 PM	298	enum ip_conntrack_info ctinfo;
212440a7 PM	299	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
3e9b4600 PM	300	unsigned int matchoff, matchlen;
	301	char buffer[sizeof("65536")];
	302	int buflen, c_len;
9fafcd7b	303
3e9b4600 PM	304	/* Get actual SDP length */
	305	if (ct_sip_get_sdp_header(ct, dptr, 0, datalen,
	306	SDP_HDR_VERSION, SDP_HDR_UNSPEC,
	307	&matchoff, &matchlen) <= 0)
	308	return 0;
	309	c_len = *datalen - matchoff + strlen("v=");
	310
	311	/* Now, update SDP length */
ea45f12a PM	312	if (ct_sip_get_header(ct, dptr, 0, datalen, SIP_HDR_CONTENT_LENGTH,
ea45f12a PM	313	&matchoff, &matchlen) <= 0)
9fafcd7b PM	314	return 0;
9fafcd7b PM	315
3e9b4600	316	buflen = sprintf(buffer, "%u", c_len);
2a6cfb22	317	return mangle_packet(skb, dptr, datalen, matchoff, matchlen,
3e9b4600	318	buffer, buflen);
9fafcd7b PM	319	}
9fafcd7b PM	320
4ab9e64e PM	321	static unsigned mangle_sdp_packet(struct sk_buff skb, const char *dptr,
4ab9e64e PM	322	unsigned int dataoff, unsigned int *datalen,
3e9b4600	323	enum sdp_header_types type,
4ab9e64e	324	enum sdp_header_types term,
3e9b4600	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
4ab9e64e	331	if (ct_sip_get_sdp_header(ct, dptr, dataoff, datalen, type, term,
3e9b4600 PM	332	&matchoff, &matchlen) <= 0)
	333	return 0;
	334	return mangle_packet(skb, dptr, datalen, matchoff, matchlen,
	335	buffer, buflen);
9fafcd7b PM	336	}
9fafcd7b PM	337
4ab9e64e PM	338	static unsigned int ip_nat_sdp_addr(struct sk_buff skb, const char *dptr,
	339	unsigned int dataoff,
	340	unsigned int *datalen,
	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
4ab9e64e PM	348	buflen = sprintf(buffer, NIPQUAD_FMT, NIPQUAD(addr->ip));
	349	if (!mangle_sdp_packet(skb, dptr, dataoff, datalen, type, term,
	350	buffer, buflen))
9fafcd7b PM	351	return 0;
9fafcd7b PM	352
4ab9e64e PM	353	return mangle_content_len(skb, dptr, datalen);
	354	}
	355
	356	static unsigned int ip_nat_sdp_port(struct sk_buff *skb,
	357	const char **dptr,
	358	unsigned int *datalen,
	359	unsigned int matchoff,
	360	unsigned int matchlen,
	361	u_int16_t port)
	362	{
	363	char buffer[sizeof("nnnnn")];
	364	unsigned int buflen;
	365
	366	buflen = sprintf(buffer, "%u", port);
	367	if (!mangle_packet(skb, dptr, datalen, matchoff, matchlen,
	368	buffer, buflen))
9fafcd7b PM	369	return 0;
9fafcd7b PM	370
4ab9e64e PM	371	return mangle_content_len(skb, dptr, datalen);
	372	}
	373
	374	static unsigned int ip_nat_sdp_session(struct sk_buff skb, const char *dptr,
	375	unsigned int dataoff,
	376	unsigned int *datalen,
	377	const union nf_inet_addr *addr)
	378	{
	379	char buffer[sizeof("nnn.nnn.nnn.nnn")];
	380	unsigned int buflen;
	381
	382	/* Mangle session description owner and contact addresses */
	383	buflen = sprintf(buffer, "%u.%u.%u.%u", NIPQUAD(addr->ip));
	384	if (!mangle_sdp_packet(skb, dptr, dataoff, datalen,
	385	SDP_HDR_OWNER_IP4, SDP_HDR_MEDIA,
	386	buffer, buflen))
	387	return 0;
	388
	389	if (!mangle_sdp_packet(skb, dptr, dataoff, datalen,
	390	SDP_HDR_CONNECTION_IP4, SDP_HDR_MEDIA,
	391	buffer, buflen))
9fafcd7b PM	392	return 0;
9fafcd7b PM	393
212440a7	394	return mangle_content_len(skb, dptr, datalen);
9fafcd7b PM	395	}
	396
	397	/* So, this packet has hit the connection tracking matching code.
	398	Mangle it, and change the expectation to match the new version. */
4ab9e64e PM	399	static unsigned int ip_nat_sdp_media(struct sk_buff *skb,
	400	const char **dptr,
	401	unsigned int *datalen,
	402	struct nf_conntrack_expect *rtp_exp,
	403	struct nf_conntrack_expect *rtcp_exp,
	404	unsigned int mediaoff,
	405	unsigned int medialen,
	406	union nf_inet_addr *rtp_addr)
9fafcd7b	407	{
212440a7 PM	408	enum ip_conntrack_info ctinfo;
212440a7 PM	409	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
9fafcd7b	410	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
9fafcd7b PM	411	u_int16_t port;
9fafcd7b PM	412
9fafcd7b	413	/* Connection will come from reply */
f4a607bf JB	414	if (ct->tuplehash[dir].tuple.src.u3.ip ==
f4a607bf JB	415	ct->tuplehash[!dir].tuple.dst.u3.ip)
4ab9e64e	416	rtp_addr->ip = rtp_exp->tuple.dst.u3.ip;
f4a607bf	417	else
4ab9e64e	418	rtp_addr->ip = ct->tuplehash[!dir].tuple.dst.u3.ip;
9fafcd7b	419
a9c1d359	420	rtp_exp->saved_ip = rtp_exp->tuple.dst.u3.ip;
4ab9e64e	421	rtp_exp->tuple.dst.u3.ip = rtp_addr->ip;
a9c1d359 PM	422	rtp_exp->saved_proto.udp.port = rtp_exp->tuple.dst.u.udp.port;
	423	rtp_exp->dir = !dir;
	424	rtp_exp->expectfn = ip_nat_sip_expected;
	425
	426	rtcp_exp->saved_ip = rtcp_exp->tuple.dst.u3.ip;
4ab9e64e	427	rtcp_exp->tuple.dst.u3.ip = rtp_addr->ip;
a9c1d359 PM	428	rtcp_exp->saved_proto.udp.port = rtcp_exp->tuple.dst.u.udp.port;
	429	rtcp_exp->dir = !dir;
	430	rtcp_exp->expectfn = ip_nat_sip_expected;
	431
	432	/* Try to get same pair of ports: if not, try to change them. */
	433	for (port = ntohs(rtp_exp->tuple.dst.u.udp.port);
	434	port != 0; port += 2) {
	435	rtp_exp->tuple.dst.u.udp.port = htons(port);
	436	if (nf_ct_expect_related(rtp_exp) != 0)
	437	continue;
	438	rtcp_exp->tuple.dst.u.udp.port = htons(port + 1);
	439	if (nf_ct_expect_related(rtcp_exp) == 0)
9fafcd7b	440	break;
a9c1d359	441	nf_ct_unexpect_related(rtp_exp);
9fafcd7b PM	442	}
	443
	444	if (port == 0)
4ab9e64e PM	445	goto err1;
	446
	447	/* Update media port. */
	448	if (rtp_exp->tuple.dst.u.udp.port != rtp_exp->saved_proto.udp.port &&
	449	!ip_nat_sdp_port(skb, dptr, datalen, mediaoff, medialen, port))
	450	goto err2;
9fafcd7b	451
9fafcd7b	452	return NF_ACCEPT;
4ab9e64e PM	453
	454	err2:
	455	nf_ct_unexpect_related(rtp_exp);
	456	nf_ct_unexpect_related(rtcp_exp);
	457	err1:
	458	return NF_DROP;
9fafcd7b PM	459	}
	460
	461	static void __exit nf_nat_sip_fini(void)
	462	{
	463	rcu_assign_pointer(nf_nat_sip_hook, NULL);
0f32a40f	464	rcu_assign_pointer(nf_nat_sip_expect_hook, NULL);
4ab9e64e	465	rcu_assign_pointer(nf_nat_sdp_addr_hook, NULL);
c7f485ab	466	rcu_assign_pointer(nf_nat_sdp_port_hook, NULL);
4ab9e64e PM	467	rcu_assign_pointer(nf_nat_sdp_session_hook, NULL);
4ab9e64e PM	468	rcu_assign_pointer(nf_nat_sdp_media_hook, NULL);
9fafcd7b PM	469	synchronize_rcu();
	470	}
	471
	472	static int __init nf_nat_sip_init(void)
	473	{
d1332e0a	474	BUG_ON(nf_nat_sip_hook != NULL);
0f32a40f	475	BUG_ON(nf_nat_sip_expect_hook != NULL);
4ab9e64e	476	BUG_ON(nf_nat_sdp_addr_hook != NULL);
c7f485ab	477	BUG_ON(nf_nat_sdp_port_hook != NULL);
4ab9e64e PM	478	BUG_ON(nf_nat_sdp_session_hook != NULL);
4ab9e64e PM	479	BUG_ON(nf_nat_sdp_media_hook != NULL);
9fafcd7b	480	rcu_assign_pointer(nf_nat_sip_hook, ip_nat_sip);
0f32a40f	481	rcu_assign_pointer(nf_nat_sip_expect_hook, ip_nat_sip_expect);
4ab9e64e	482	rcu_assign_pointer(nf_nat_sdp_addr_hook, ip_nat_sdp_addr);
c7f485ab	483	rcu_assign_pointer(nf_nat_sdp_port_hook, ip_nat_sdp_port);
4ab9e64e PM	484	rcu_assign_pointer(nf_nat_sdp_session_hook, ip_nat_sdp_session);
4ab9e64e PM	485	rcu_assign_pointer(nf_nat_sdp_media_hook, ip_nat_sdp_media);
9fafcd7b PM	486	return 0;
	487	}
	488
	489	module_init(nf_nat_sip_init);
	490	module_exit(nf_nat_sip_fini);