net/netfilter/xt_socket.c - linux-mtk - Git at Google

 /*
  * Transparent proxy support for Linux/iptables
  *
  * Copyright (C) 2007-2008 BalaBit IT Ltd.
  * Author: Krisztian Kovacs
  *
  * 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.
  *
  */
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 #include <linux/module.h>
 #include <linux/skbuff.h>
 #include <linux/netfilter/x_tables.h>
 #include <linux/netfilter_ipv4/ip_tables.h>
 #include <net/tcp.h>
 #include <net/udp.h>
 #include <net/icmp.h>
 #include <net/sock.h>
 #include <net/inet_sock.h>
 #include <net/netfilter/ipv4/nf_defrag_ipv4.h>

 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
 #define XT_SOCKET_HAVE_IPV6 1
 #include <linux/netfilter_ipv6/ip6_tables.h>
 #include <net/inet6_hashtables.h>
 #include <net/netfilter/ipv6/nf_defrag_ipv6.h>
 #endif

 #include <linux/netfilter/xt_socket.h>

 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
 #define XT_SOCKET_HAVE_CONNTRACK 1
 #include <net/netfilter/nf_conntrack.h>
 #endif

 static int
 extract_icmp4_fields(const struct sk_buff *skb,
 		    u8 *protocol,
 		    __be32 *raddr,
 		    __be32 *laddr,
 		    __be16 *rport,
 		    __be16 *lport)
 {
 	unsigned int outside_hdrlen = ip_hdrlen(skb);
 	struct iphdr *inside_iph, _inside_iph;
 	struct icmphdr *icmph, _icmph;
 	__be16 *ports, _ports[2];

 	icmph = skb_header_pointer(skb, outside_hdrlen,
 				   sizeof(_icmph), &_icmph);
 	if (icmph == NULL)
 		return 1;

 	switch (icmph->type) {
 	case ICMP_DEST_UNREACH:
 	case ICMP_SOURCE_QUENCH:
 	case ICMP_REDIRECT:
 	case ICMP_TIME_EXCEEDED:
 	case ICMP_PARAMETERPROB:
 		break;
 	default:
 		return 1;
 	}

 	inside_iph = skb_header_pointer(skb, outside_hdrlen +
 					sizeof(struct icmphdr),
 					sizeof(_inside_iph), &_inside_iph);
 	if (inside_iph == NULL)
 		return 1;

 	if (inside_iph->protocol != IPPROTO_TCP &&
 	    inside_iph->protocol != IPPROTO_UDP)
 		return 1;

 	ports = skb_header_pointer(skb, outside_hdrlen +
 				   sizeof(struct icmphdr) +
 				   (inside_iph->ihl << 2),
 				   sizeof(_ports), &_ports);
 	if (ports == NULL)
 		return 1;

 	/* the inside IP packet is the one quoted from our side, thus
 	 * its saddr is the local address */
 	*protocol = inside_iph->protocol;
 	*laddr = inside_iph->saddr;
 	*lport = ports[0];
 	*raddr = inside_iph->daddr;
 	*rport = ports[1];

 	return 0;
 }

 /* "socket" match based redirection (no specific rule)
  * ===================================================
  *
  * There are connections with dynamic endpoints (e.g. FTP data
  * connection) that the user is unable to add explicit rules
  * for. These are taken care of by a generic "socket" rule. It is
  * assumed that the proxy application is trusted to open such
  * connections without explicit iptables rule (except of course the
  * generic 'socket' rule). In this case the following sockets are
  * matched in preference order:
  *
  *   - match: if there's a fully established connection matching the
  *     _packet_ tuple
  *
  *   - match: if there's a non-zero bound listener (possibly with a
  *     non-local address) We don't accept zero-bound listeners, since
  *     then local services could intercept traffic going through the
  *     box.
  */
 static struct sock *
 xt_socket_get_sock_v4(struct net *net, const u8 protocol,
 		      const __be32 saddr, const __be32 daddr,
 		      const __be16 sport, const __be16 dport,
 		      const struct net_device *in)
 {
 	switch (protocol) {
 	case IPPROTO_TCP:
 		return __inet_lookup(net, &tcp_hashinfo,
 				     saddr, sport, daddr, dport,
 				     in->ifindex);
 	case IPPROTO_UDP:
 		return udp4_lib_lookup(net, saddr, sport, daddr, dport,
 				       in->ifindex);
 	}
 	return NULL;
 }

 static bool
 socket_match(const struct sk_buff *skb, struct xt_action_param *par,
 	     const struct xt_socket_mtinfo1 *info)
 {
 	const struct iphdr *iph = ip_hdr(skb);
 	struct udphdr _hdr, *hp = NULL;
 	struct sock *sk = skb->sk;
 	__be32 uninitialized_var(daddr), uninitialized_var(saddr);
 	__be16 uninitialized_var(dport), uninitialized_var(sport);
 	u8 uninitialized_var(protocol);
 #ifdef XT_SOCKET_HAVE_CONNTRACK
 	struct nf_conn const *ct;
 	enum ip_conntrack_info ctinfo;
 #endif

 	if (iph->protocol == IPPROTO_UDP || iph->protocol == IPPROTO_TCP) {
 		hp = skb_header_pointer(skb, ip_hdrlen(skb),
 					sizeof(_hdr), &_hdr);
 		if (hp == NULL)
 			return false;

 		protocol = iph->protocol;
 		saddr = iph->saddr;
 		sport = hp->source;
 		daddr = iph->daddr;
 		dport = hp->dest;

 	} else if (iph->protocol == IPPROTO_ICMP) {
 		if (extract_icmp4_fields(skb, &protocol, &saddr, &daddr,
 					&sport, &dport))
 			return false;
 	} else {
 		return false;
 	}

 #ifdef XT_SOCKET_HAVE_CONNTRACK
 	/* Do the lookup with the original socket address in case this is a
 	 * reply packet of an established SNAT-ted connection. */

 	ct = nf_ct_get(skb, &ctinfo);
 	if (ct && !nf_ct_is_untracked(ct) &&
 	    ((iph->protocol != IPPROTO_ICMP &&
 	      ctinfo == IP_CT_ESTABLISHED_REPLY) ||
 	     (iph->protocol == IPPROTO_ICMP &&
 	      ctinfo == IP_CT_RELATED_REPLY)) &&
 	    (ct->status & IPS_SRC_NAT_DONE)) {

 		daddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip;
 		dport = (iph->protocol == IPPROTO_TCP) ?
 			ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.tcp.port :
 			ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port;
 	}
 #endif

 	if (!sk)
 		sk = xt_socket_get_sock_v4(dev_net(skb->dev), protocol,
 					   saddr, daddr, sport, dport,
 					   par->in);
 	if (sk) {
 		bool wildcard;
 		bool transparent = true;

 		/* Ignore sockets listening on INADDR_ANY,
 		 * unless XT_SOCKET_NOWILDCARD is set
 		 */
 		wildcard = (!(info->flags & XT_SOCKET_NOWILDCARD) &&
 			    sk->sk_state != TCP_TIME_WAIT &&
 			    inet_sk(sk)->inet_rcv_saddr == 0);

 		/* Ignore non-transparent sockets,
 		   if XT_SOCKET_TRANSPARENT is used */
 		if (info->flags & XT_SOCKET_TRANSPARENT)
 			transparent = ((sk->sk_state != TCP_TIME_WAIT &&
 					inet_sk(sk)->transparent) ||
 				       (sk->sk_state == TCP_TIME_WAIT &&
 					inet_twsk(sk)->tw_transparent));

 		if (sk != skb->sk)
 			sock_gen_put(sk);

 		if (wildcard || !transparent)
 			sk = NULL;
 	}

 	pr_debug("proto %hhu %pI4:%hu -> %pI4:%hu (orig %pI4:%hu) sock %p\n",
 		 protocol, &saddr, ntohs(sport),
 		 &daddr, ntohs(dport),
 		 &iph->daddr, hp ? ntohs(hp->dest) : 0, sk);

 	return (sk != NULL);
 }

 static bool
 socket_mt4_v0(const struct sk_buff *skb, struct xt_action_param *par)
 {
 	static struct xt_socket_mtinfo1 xt_info_v0 = {
 		.flags = 0,
 	};

 	return socket_match(skb, par, &xt_info_v0);
 }

 static bool
 socket_mt4_v1_v2(const struct sk_buff *skb, struct xt_action_param *par)
 {
 	return socket_match(skb, par, par->matchinfo);
 }

 #ifdef XT_SOCKET_HAVE_IPV6

 static int
 extract_icmp6_fields(const struct sk_buff *skb,
 		     unsigned int outside_hdrlen,
 		     int *protocol,
 		     struct in6_addr **raddr,
 		     struct in6_addr **laddr,
 		     __be16 *rport,
 		     __be16 *lport)
 {
 	struct ipv6hdr *inside_iph, _inside_iph;
 	struct icmp6hdr *icmph, _icmph;
 	__be16 *ports, _ports[2];
 	u8 inside_nexthdr;
 	__be16 inside_fragoff;
 	int inside_hdrlen;

 	icmph = skb_header_pointer(skb, outside_hdrlen,
 				   sizeof(_icmph), &_icmph);
 	if (icmph == NULL)
 		return 1;

 	if (icmph->icmp6_type & ICMPV6_INFOMSG_MASK)
 		return 1;

 	inside_iph = skb_header_pointer(skb, outside_hdrlen + sizeof(_icmph), sizeof(_inside_iph), &_inside_iph);
 	if (inside_iph == NULL)
 		return 1;
 	inside_nexthdr = inside_iph->nexthdr;

 	inside_hdrlen = ipv6_skip_exthdr(skb, outside_hdrlen + sizeof(_icmph) + sizeof(_inside_iph),
 					 &inside_nexthdr, &inside_fragoff);
 	if (inside_hdrlen < 0)
 		return 1; /* hjm: Packet has no/incomplete transport layer headers. */

 	if (inside_nexthdr != IPPROTO_TCP &&
 	    inside_nexthdr != IPPROTO_UDP)
 		return 1;

 	ports = skb_header_pointer(skb, inside_hdrlen,
 				   sizeof(_ports), &_ports);
 	if (ports == NULL)
 		return 1;

 	/* the inside IP packet is the one quoted from our side, thus
 	 * its saddr is the local address */
 	*protocol = inside_nexthdr;
 	*laddr = &inside_iph->saddr;
 	*lport = ports[0];
 	*raddr = &inside_iph->daddr;
 	*rport = ports[1];

 	return 0;
 }

 static struct sock *
 xt_socket_get_sock_v6(struct net *net, const u8 protocol,
 		      const struct in6_addr *saddr, const struct in6_addr *daddr,
 		      const __be16 sport, const __be16 dport,
 		      const struct net_device *in)
 {
 	switch (protocol) {
 	case IPPROTO_TCP:
 		return inet6_lookup(net, &tcp_hashinfo,
 				    saddr, sport, daddr, dport,
 				    in->ifindex);
 	case IPPROTO_UDP:
 		return udp6_lib_lookup(net, saddr, sport, daddr, dport,
 				       in->ifindex);
 	}

 	return NULL;
 }

 static bool
 socket_mt6_v1_v2(const struct sk_buff *skb, struct xt_action_param *par)
 {
 	struct ipv6hdr *iph = ipv6_hdr(skb);
 	struct udphdr _hdr, *hp = NULL;
 	struct sock *sk = skb->sk;
 	struct in6_addr *daddr = NULL, *saddr = NULL;
 	__be16 uninitialized_var(dport), uninitialized_var(sport);
 	int thoff = 0, uninitialized_var(tproto);
 	const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo;

 	tproto = ipv6_find_hdr(skb, &thoff, -1, NULL, NULL);
 	if (tproto < 0) {
 		pr_debug("unable to find transport header in IPv6 packet, dropping\n");
 		return NF_DROP;
 	}

 	if (tproto == IPPROTO_UDP || tproto == IPPROTO_TCP) {
 		hp = skb_header_pointer(skb, thoff,
 					sizeof(_hdr), &_hdr);
 		if (hp == NULL)
 			return false;

 		saddr = &iph->saddr;
 		sport = hp->source;
 		daddr = &iph->daddr;
 		dport = hp->dest;

 	} else if (tproto == IPPROTO_ICMPV6) {
 		if (extract_icmp6_fields(skb, thoff, &tproto, &saddr, &daddr,
 					 &sport, &dport))
 			return false;
 	} else {
 		return false;
 	}

 	if (!sk)
 		sk = xt_socket_get_sock_v6(dev_net(skb->dev), tproto,
 					   saddr, daddr, sport, dport,
 					   par->in);
 	if (sk) {
 		bool wildcard;
 		bool transparent = true;

 		/* Ignore sockets listening on INADDR_ANY
 		 * unless XT_SOCKET_NOWILDCARD is set
 		 */
 		wildcard = (!(info->flags & XT_SOCKET_NOWILDCARD) &&
 			    sk->sk_state != TCP_TIME_WAIT &&
 			    ipv6_addr_any(&sk->sk_v6_rcv_saddr));

 		/* Ignore non-transparent sockets,
 		   if XT_SOCKET_TRANSPARENT is used */
 		if (info->flags & XT_SOCKET_TRANSPARENT)
 			transparent = ((sk->sk_state != TCP_TIME_WAIT &&
 					inet_sk(sk)->transparent) ||
 				       (sk->sk_state == TCP_TIME_WAIT &&
 					inet_twsk(sk)->tw_transparent));

 		if (sk != skb->sk)
 			sock_gen_put(sk);

 		if (wildcard || !transparent)
 			sk = NULL;
 	}

 	pr_debug("proto %hhd %pI6:%hu -> %pI6:%hu "
 		 "(orig %pI6:%hu) sock %p\n",
 		 tproto, saddr, ntohs(sport),
 		 daddr, ntohs(dport),
 		 &iph->daddr, hp ? ntohs(hp->dest) : 0, sk);

 	return (sk != NULL);
 }
 #endif

 static int socket_mt_v1_check(const struct xt_mtchk_param *par)
 {
 	const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo;

 	if (info->flags & ~XT_SOCKET_FLAGS_V1) {
 		pr_info("unknown flags 0x%x\n", info->flags & ~XT_SOCKET_FLAGS_V1);
 		return -EINVAL;
 	}
 	return 0;
 }

 static int socket_mt_v2_check(const struct xt_mtchk_param *par)
 {
 	const struct xt_socket_mtinfo2 *info = (struct xt_socket_mtinfo2 *) par->matchinfo;

 	if (info->flags & ~XT_SOCKET_FLAGS_V2) {
 		pr_info("unknown flags 0x%x\n", info->flags & ~XT_SOCKET_FLAGS_V2);
 		return -EINVAL;
 	}
 	return 0;
 }

 static struct xt_match socket_mt_reg[] __read_mostly = {
 	{
 		.name		= "socket",
 		.revision	= 0,
 		.family		= NFPROTO_IPV4,
 		.match		= socket_mt4_v0,
 		.hooks		= (1 << NF_INET_PRE_ROUTING) |
 				  (1 << NF_INET_LOCAL_IN),
 		.me		= THIS_MODULE,
 	},
 	{
 		.name		= "socket",
 		.revision	= 1,
 		.family		= NFPROTO_IPV4,
 		.match		= socket_mt4_v1_v2,
 		.checkentry	= socket_mt_v1_check,
 		.matchsize	= sizeof(struct xt_socket_mtinfo1),
 		.hooks		= (1 << NF_INET_PRE_ROUTING) |
 				  (1 << NF_INET_LOCAL_IN),
 		.me		= THIS_MODULE,
 	},
 #ifdef XT_SOCKET_HAVE_IPV6
 	{
 		.name		= "socket",
 		.revision	= 1,
 		.family		= NFPROTO_IPV6,
 		.match		= socket_mt6_v1_v2,
 		.checkentry	= socket_mt_v1_check,
 		.matchsize	= sizeof(struct xt_socket_mtinfo1),
 		.hooks		= (1 << NF_INET_PRE_ROUTING) |
 				  (1 << NF_INET_LOCAL_IN),
 		.me		= THIS_MODULE,
 	},
 #endif
 	{
 		.name		= "socket",
 		.revision	= 2,
 		.family		= NFPROTO_IPV4,
 		.match		= socket_mt4_v1_v2,
 		.checkentry	= socket_mt_v2_check,
 		.matchsize	= sizeof(struct xt_socket_mtinfo1),
 		.hooks		= (1 << NF_INET_PRE_ROUTING) |
 				  (1 << NF_INET_LOCAL_IN),
 		.me		= THIS_MODULE,
 	},
 #ifdef XT_SOCKET_HAVE_IPV6
 	{
 		.name		= "socket",
 		.revision	= 2,
 		.family		= NFPROTO_IPV6,
 		.match		= socket_mt6_v1_v2,
 		.checkentry	= socket_mt_v2_check,
 		.matchsize	= sizeof(struct xt_socket_mtinfo1),
 		.hooks		= (1 << NF_INET_PRE_ROUTING) |
 				  (1 << NF_INET_LOCAL_IN),
 		.me		= THIS_MODULE,
 	},
 #endif
 };

 static int __init socket_mt_init(void)
 {
 	nf_defrag_ipv4_enable();
 #ifdef XT_SOCKET_HAVE_IPV6
 	nf_defrag_ipv6_enable();
 #endif

 	return xt_register_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg));
 }

 static void __exit socket_mt_exit(void)
 {
 	xt_unregister_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg));
 }

 module_init(socket_mt_init);
 module_exit(socket_mt_exit);

 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler");
 MODULE_DESCRIPTION("x_tables socket match module");
 MODULE_ALIAS("ipt_socket");
 MODULE_ALIAS("ip6t_socket");
	/*
	* Transparent proxy support for Linux/iptables
	*
	* Copyright (C) 2007-2008 BalaBit IT Ltd.
	* Author: Krisztian Kovacs
	*
	* 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.
	*
	*/
	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
	#include <linux/module.h>
	#include <linux/skbuff.h>
	#include <linux/netfilter/x_tables.h>
	#include <linux/netfilter_ipv4/ip_tables.h>
	#include <net/tcp.h>
	#include <net/udp.h>
	#include <net/icmp.h>
	#include <net/sock.h>
	#include <net/inet_sock.h>
	#include <net/netfilter/ipv4/nf_defrag_ipv4.h>

	#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
	#define XT_SOCKET_HAVE_IPV6 1
	#include <linux/netfilter_ipv6/ip6_tables.h>
	#include <net/inet6_hashtables.h>
	#include <net/netfilter/ipv6/nf_defrag_ipv6.h>
	#endif

	#include <linux/netfilter/xt_socket.h>

	#if IS_ENABLED(CONFIG_NF_CONNTRACK)
	#define XT_SOCKET_HAVE_CONNTRACK 1
	#include <net/netfilter/nf_conntrack.h>
	#endif

	static int
	extract_icmp4_fields(const struct sk_buff *skb,
	u8 *protocol,
	__be32 *raddr,
	__be32 *laddr,
	__be16 *rport,
	__be16 *lport)
	{
	unsigned int outside_hdrlen = ip_hdrlen(skb);
	struct iphdr *inside_iph, _inside_iph;
	struct icmphdr *icmph, _icmph;
	__be16 *ports, _ports[2];

	icmph = skb_header_pointer(skb, outside_hdrlen,
	sizeof(_icmph), &_icmph);
	if (icmph == NULL)
	return 1;

	switch (icmph->type) {
	case ICMP_DEST_UNREACH:
	case ICMP_SOURCE_QUENCH:
	case ICMP_REDIRECT:
	case ICMP_TIME_EXCEEDED:
	case ICMP_PARAMETERPROB:
	break;
	default:
	return 1;
	}

	inside_iph = skb_header_pointer(skb, outside_hdrlen +
	sizeof(struct icmphdr),
	sizeof(_inside_iph), &_inside_iph);
	if (inside_iph == NULL)
	return 1;

	if (inside_iph->protocol != IPPROTO_TCP &&
	inside_iph->protocol != IPPROTO_UDP)
	return 1;

	ports = skb_header_pointer(skb, outside_hdrlen +
	sizeof(struct icmphdr) +
	(inside_iph->ihl << 2),
	sizeof(_ports), &_ports);
	if (ports == NULL)
	return 1;

	/* the inside IP packet is the one quoted from our side, thus
	* its saddr is the local address */
	*protocol = inside_iph->protocol;
	*laddr = inside_iph->saddr;
	*lport = ports[0];
	*raddr = inside_iph->daddr;
	*rport = ports[1];

	return 0;
	}

	/* "socket" match based redirection (no specific rule)
	* ===================================================
	*
	* There are connections with dynamic endpoints (e.g. FTP data
	* connection) that the user is unable to add explicit rules
	* for. These are taken care of by a generic "socket" rule. It is
	* assumed that the proxy application is trusted to open such
	* connections without explicit iptables rule (except of course the
	* generic 'socket' rule). In this case the following sockets are
	* matched in preference order:
	*
	* - match: if there's a fully established connection matching the
	* _packet_ tuple
	*
	* - match: if there's a non-zero bound listener (possibly with a
	* non-local address) We don't accept zero-bound listeners, since
	* then local services could intercept traffic going through the
	* box.
	*/
	static struct sock *
	xt_socket_get_sock_v4(struct net *net, const u8 protocol,
	const __be32 saddr, const __be32 daddr,
	const __be16 sport, const __be16 dport,
	const struct net_device *in)
	{
	switch (protocol) {
	case IPPROTO_TCP:
	return __inet_lookup(net, &tcp_hashinfo,
	saddr, sport, daddr, dport,
	in->ifindex);
	case IPPROTO_UDP:
	return udp4_lib_lookup(net, saddr, sport, daddr, dport,
	in->ifindex);
	}
	return NULL;
	}

	static bool
	socket_match(const struct sk_buff skb, struct xt_action_param par,
	const struct xt_socket_mtinfo1 *info)
	{
	const struct iphdr *iph = ip_hdr(skb);
	struct udphdr _hdr, *hp = NULL;
	struct sock *sk = skb->sk;
	__be32 uninitialized_var(daddr), uninitialized_var(saddr);
	__be16 uninitialized_var(dport), uninitialized_var(sport);
	u8 uninitialized_var(protocol);
	#ifdef XT_SOCKET_HAVE_CONNTRACK
	struct nf_conn const *ct;
	enum ip_conntrack_info ctinfo;
	#endif

	if (iph->protocol == IPPROTO_UDP \|\| iph->protocol == IPPROTO_TCP) {
	hp = skb_header_pointer(skb, ip_hdrlen(skb),
	sizeof(_hdr), &_hdr);
	if (hp == NULL)
	return false;

	protocol = iph->protocol;
	saddr = iph->saddr;
	sport = hp->source;
	daddr = iph->daddr;
	dport = hp->dest;

	} else if (iph->protocol == IPPROTO_ICMP) {
	if (extract_icmp4_fields(skb, &protocol, &saddr, &daddr,
	&sport, &dport))
	return false;
	} else {
	return false;
	}

	#ifdef XT_SOCKET_HAVE_CONNTRACK
	/* Do the lookup with the original socket address in case this is a
	* reply packet of an established SNAT-ted connection. */

	ct = nf_ct_get(skb, &ctinfo);
	if (ct && !nf_ct_is_untracked(ct) &&
	((iph->protocol != IPPROTO_ICMP &&
	ctinfo == IP_CT_ESTABLISHED_REPLY) \|\|
	(iph->protocol == IPPROTO_ICMP &&
	ctinfo == IP_CT_RELATED_REPLY)) &&
	(ct->status & IPS_SRC_NAT_DONE)) {

	daddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip;
	dport = (iph->protocol == IPPROTO_TCP) ?
	ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.tcp.port :
	ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port;
	}
	#endif

	if (!sk)
	sk = xt_socket_get_sock_v4(dev_net(skb->dev), protocol,
	saddr, daddr, sport, dport,
	par->in);
	if (sk) {
	bool wildcard;
	bool transparent = true;

	/* Ignore sockets listening on INADDR_ANY,
	* unless XT_SOCKET_NOWILDCARD is set
	*/
	wildcard = (!(info->flags & XT_SOCKET_NOWILDCARD) &&
	sk->sk_state != TCP_TIME_WAIT &&
	inet_sk(sk)->inet_rcv_saddr == 0);

	/* Ignore non-transparent sockets,
	if XT_SOCKET_TRANSPARENT is used */
	if (info->flags & XT_SOCKET_TRANSPARENT)
	transparent = ((sk->sk_state != TCP_TIME_WAIT &&
	inet_sk(sk)->transparent) \|\|
	(sk->sk_state == TCP_TIME_WAIT &&
	inet_twsk(sk)->tw_transparent));

	if (sk != skb->sk)
	sock_gen_put(sk);

	if (wildcard \|\| !transparent)
	sk = NULL;
	}

	pr_debug("proto %hhu %pI4:%hu -> %pI4:%hu (orig %pI4:%hu) sock %p\n",
	protocol, &saddr, ntohs(sport),
	&daddr, ntohs(dport),
	&iph->daddr, hp ? ntohs(hp->dest) : 0, sk);

	return (sk != NULL);
	}

	static bool
	socket_mt4_v0(const struct sk_buff skb, struct xt_action_param par)
	{
	static struct xt_socket_mtinfo1 xt_info_v0 = {
	.flags = 0,
	};

	return socket_match(skb, par, &xt_info_v0);
	}

	static bool
	socket_mt4_v1_v2(const struct sk_buff skb, struct xt_action_param par)
	{
	return socket_match(skb, par, par->matchinfo);
	}

	#ifdef XT_SOCKET_HAVE_IPV6

	static int
	extract_icmp6_fields(const struct sk_buff *skb,
	unsigned int outside_hdrlen,
	int *protocol,
	struct in6_addr **raddr,
	struct in6_addr **laddr,
	__be16 *rport,
	__be16 *lport)
	{
	struct ipv6hdr *inside_iph, _inside_iph;
	struct icmp6hdr *icmph, _icmph;
	__be16 *ports, _ports[2];
	u8 inside_nexthdr;
	__be16 inside_fragoff;
	int inside_hdrlen;

	icmph = skb_header_pointer(skb, outside_hdrlen,
	sizeof(_icmph), &_icmph);
	if (icmph == NULL)
	return 1;

	if (icmph->icmp6_type & ICMPV6_INFOMSG_MASK)
	return 1;

	inside_iph = skb_header_pointer(skb, outside_hdrlen + sizeof(_icmph), sizeof(_inside_iph), &_inside_iph);
	if (inside_iph == NULL)
	return 1;
	inside_nexthdr = inside_iph->nexthdr;

	inside_hdrlen = ipv6_skip_exthdr(skb, outside_hdrlen + sizeof(_icmph) + sizeof(_inside_iph),
	&inside_nexthdr, &inside_fragoff);
	if (inside_hdrlen < 0)
	return 1; /* hjm: Packet has no/incomplete transport layer headers. */

	if (inside_nexthdr != IPPROTO_TCP &&
	inside_nexthdr != IPPROTO_UDP)
	return 1;

	ports = skb_header_pointer(skb, inside_hdrlen,
	sizeof(_ports), &_ports);
	if (ports == NULL)
	return 1;

	/* the inside IP packet is the one quoted from our side, thus
	* its saddr is the local address */
	*protocol = inside_nexthdr;
	*laddr = &inside_iph->saddr;
	*lport = ports[0];
	*raddr = &inside_iph->daddr;
	*rport = ports[1];

	return 0;
	}

	static struct sock *
	xt_socket_get_sock_v6(struct net *net, const u8 protocol,
	const struct in6_addr saddr, const struct in6_addr daddr,
	const __be16 sport, const __be16 dport,
	const struct net_device *in)
	{
	switch (protocol) {
	case IPPROTO_TCP:
	return inet6_lookup(net, &tcp_hashinfo,
	saddr, sport, daddr, dport,
	in->ifindex);
	case IPPROTO_UDP:
	return udp6_lib_lookup(net, saddr, sport, daddr, dport,
	in->ifindex);
	}

	return NULL;
	}

	static bool
	socket_mt6_v1_v2(const struct sk_buff skb, struct xt_action_param par)
	{
	struct ipv6hdr *iph = ipv6_hdr(skb);
	struct udphdr _hdr, *hp = NULL;
	struct sock *sk = skb->sk;
	struct in6_addr daddr = NULL, saddr = NULL;
	__be16 uninitialized_var(dport), uninitialized_var(sport);
	int thoff = 0, uninitialized_var(tproto);
	const struct xt_socket_mtinfo1 info = (struct xt_socket_mtinfo1 ) par->matchinfo;

	tproto = ipv6_find_hdr(skb, &thoff, -1, NULL, NULL);
	if (tproto < 0) {
	pr_debug("unable to find transport header in IPv6 packet, dropping\n");
	return NF_DROP;
	}

	if (tproto == IPPROTO_UDP \|\| tproto == IPPROTO_TCP) {
	hp = skb_header_pointer(skb, thoff,
	sizeof(_hdr), &_hdr);
	if (hp == NULL)
	return false;

	saddr = &iph->saddr;
	sport = hp->source;
	daddr = &iph->daddr;
	dport = hp->dest;

	} else if (tproto == IPPROTO_ICMPV6) {
	if (extract_icmp6_fields(skb, thoff, &tproto, &saddr, &daddr,
	&sport, &dport))
	return false;
	} else {
	return false;
	}

	if (!sk)
	sk = xt_socket_get_sock_v6(dev_net(skb->dev), tproto,
	saddr, daddr, sport, dport,
	par->in);
	if (sk) {
	bool wildcard;
	bool transparent = true;

	/* Ignore sockets listening on INADDR_ANY
	* unless XT_SOCKET_NOWILDCARD is set
	*/
	wildcard = (!(info->flags & XT_SOCKET_NOWILDCARD) &&
	sk->sk_state != TCP_TIME_WAIT &&
	ipv6_addr_any(&sk->sk_v6_rcv_saddr));

	/* Ignore non-transparent sockets,
	if XT_SOCKET_TRANSPARENT is used */
	if (info->flags & XT_SOCKET_TRANSPARENT)
	transparent = ((sk->sk_state != TCP_TIME_WAIT &&
	inet_sk(sk)->transparent) \|\|
	(sk->sk_state == TCP_TIME_WAIT &&
	inet_twsk(sk)->tw_transparent));

	if (sk != skb->sk)
	sock_gen_put(sk);

	if (wildcard \|\| !transparent)
	sk = NULL;
	}

	pr_debug("proto %hhd %pI6:%hu -> %pI6:%hu "
	"(orig %pI6:%hu) sock %p\n",
	tproto, saddr, ntohs(sport),
	daddr, ntohs(dport),
	&iph->daddr, hp ? ntohs(hp->dest) : 0, sk);

	return (sk != NULL);
	}
	#endif

	static int socket_mt_v1_check(const struct xt_mtchk_param *par)
	{
	const struct xt_socket_mtinfo1 info = (struct xt_socket_mtinfo1 ) par->matchinfo;

	if (info->flags & ~XT_SOCKET_FLAGS_V1) {
	pr_info("unknown flags 0x%x\n", info->flags & ~XT_SOCKET_FLAGS_V1);
	return -EINVAL;
	}
	return 0;
	}

	static int socket_mt_v2_check(const struct xt_mtchk_param *par)
	{
	const struct xt_socket_mtinfo2 info = (struct xt_socket_mtinfo2 ) par->matchinfo;

	if (info->flags & ~XT_SOCKET_FLAGS_V2) {
	pr_info("unknown flags 0x%x\n", info->flags & ~XT_SOCKET_FLAGS_V2);
	return -EINVAL;
	}
	return 0;
	}

	static struct xt_match socket_mt_reg[] __read_mostly = {
	{
	.name = "socket",
	.revision = 0,
	.family = NFPROTO_IPV4,
	.match = socket_mt4_v0,
	.hooks = (1 << NF_INET_PRE_ROUTING) \|
	(1 << NF_INET_LOCAL_IN),
	.me = THIS_MODULE,
	},
	{
	.name = "socket",
	.revision = 1,
	.family = NFPROTO_IPV4,
	.match = socket_mt4_v1_v2,
	.checkentry = socket_mt_v1_check,
	.matchsize = sizeof(struct xt_socket_mtinfo1),
	.hooks = (1 << NF_INET_PRE_ROUTING) \|
	(1 << NF_INET_LOCAL_IN),
	.me = THIS_MODULE,
	},
	#ifdef XT_SOCKET_HAVE_IPV6
	{
	.name = "socket",
	.revision = 1,
	.family = NFPROTO_IPV6,
	.match = socket_mt6_v1_v2,
	.checkentry = socket_mt_v1_check,
	.matchsize = sizeof(struct xt_socket_mtinfo1),
	.hooks = (1 << NF_INET_PRE_ROUTING) \|
	(1 << NF_INET_LOCAL_IN),
	.me = THIS_MODULE,
	},
	#endif
	{
	.name = "socket",
	.revision = 2,
	.family = NFPROTO_IPV4,
	.match = socket_mt4_v1_v2,
	.checkentry = socket_mt_v2_check,
	.matchsize = sizeof(struct xt_socket_mtinfo1),
	.hooks = (1 << NF_INET_PRE_ROUTING) \|
	(1 << NF_INET_LOCAL_IN),
	.me = THIS_MODULE,
	},
	#ifdef XT_SOCKET_HAVE_IPV6
	{
	.name = "socket",
	.revision = 2,
	.family = NFPROTO_IPV6,
	.match = socket_mt6_v1_v2,
	.checkentry = socket_mt_v2_check,
	.matchsize = sizeof(struct xt_socket_mtinfo1),
	.hooks = (1 << NF_INET_PRE_ROUTING) \|
	(1 << NF_INET_LOCAL_IN),
	.me = THIS_MODULE,
	},
	#endif
	};

	static int __init socket_mt_init(void)
	{
	nf_defrag_ipv4_enable();
	#ifdef XT_SOCKET_HAVE_IPV6
	nf_defrag_ipv6_enable();
	#endif

	return xt_register_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg));
	}

	static void __exit socket_mt_exit(void)
	{
	xt_unregister_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg));
	}

	module_init(socket_mt_init);
	module_exit(socket_mt_exit);

	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler");
	MODULE_DESCRIPTION("x_tables socket match module");
	MODULE_ALIAS("ipt_socket");
	MODULE_ALIAS("ip6t_socket");