[net-next-2.6.git] / net / netfilter / xt_TPROXY.c

/*
 * Transparent proxy support for Linux/iptables
 *
 * Copyright (c) 2006-2010 BalaBit IT Ltd.
 * Author: Balazs Scheidler, 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/ip.h>
#include <net/checksum.h>
#include <net/udp.h>
#include <net/inet_sock.h>
#include <linux/inetdevice.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_ipv4/ip_tables.h>

#include <net/netfilter/ipv4/nf_defrag_ipv4.h>

#if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
#define XT_TPROXY_HAVE_IPV6 1
#include <net/if_inet6.h>
#include <net/addrconf.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <net/netfilter/ipv6/nf_defrag_ipv6.h>
#endif

#include <net/netfilter/nf_tproxy_core.h>
#include <linux/netfilter/xt_TPROXY.h>

static inline __be32
tproxy_laddr4(struct sk_buff *skb, __be32 user_laddr, __be32 daddr)
{
	struct in_device *indev;
	__be32 laddr;

	if (user_laddr)
		return user_laddr;

	laddr = 0;
	rcu_read_lock();
	indev = __in_dev_get_rcu(skb->dev);
	for_primary_ifa(indev) {
		laddr = ifa->ifa_local;
		break;
	} endfor_ifa(indev);
	rcu_read_unlock();

	return laddr ? laddr : daddr;
}

/**
 * tproxy_handle_time_wait4() - handle IPv4 TCP TIME_WAIT reopen redirections
 * @skb:	The skb being processed.
 * @laddr:	IPv4 address to redirect to or zero.
 * @lport:	TCP port to redirect to or zero.
 * @sk:		The TIME_WAIT TCP socket found by the lookup.
 *
 * We have to handle SYN packets arriving to TIME_WAIT sockets
 * differently: instead of reopening the connection we should rather
 * redirect the new connection to the proxy if there's a listener
 * socket present.
 *
 * tproxy_handle_time_wait4() consumes the socket reference passed in.
 *
 * Returns the listener socket if there's one, the TIME_WAIT socket if
 * no such listener is found, or NULL if the TCP header is incomplete.
 */
static struct sock *
tproxy_handle_time_wait4(struct sk_buff *skb, __be32 laddr, __be16 lport,
			struct sock *sk)
{
	const struct iphdr *iph = ip_hdr(skb);
	struct tcphdr _hdr, *hp;

	hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr);
	if (hp == NULL) {
		inet_twsk_put(inet_twsk(sk));
		return NULL;
	}

	if (hp->syn && !hp->rst && !hp->ack && !hp->fin) {
		/* SYN to a TIME_WAIT socket, we'd rather redirect it
		 * to a listener socket if there's one */
		struct sock *sk2;

		sk2 = nf_tproxy_get_sock_v4(dev_net(skb->dev), iph->protocol,
					    iph->saddr, laddr ? laddr : iph->daddr,
					    hp->source, lport ? lport : hp->dest,
					    skb->dev, NFT_LOOKUP_LISTENER);
		if (sk2) {
			inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row);
			inet_twsk_put(inet_twsk(sk));
			sk = sk2;
		}
	}

	return sk;
}

static unsigned int
tproxy_tg4(struct sk_buff *skb, __be32 laddr, __be16 lport,
	   u_int32_t mark_mask, u_int32_t mark_value)
{
	const struct iphdr *iph = ip_hdr(skb);
	struct udphdr _hdr, *hp;
	struct sock *sk;

	hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr);
	if (hp == NULL)
		return NF_DROP;

	/* check if there's an ongoing connection on the packet
	 * addresses, this happens if the redirect already happened
	 * and the current packet belongs to an already established
	 * connection */
	sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), iph->protocol,
				   iph->saddr, iph->daddr,
				   hp->source, hp->dest,
				   skb->dev, NFT_LOOKUP_ESTABLISHED);

	laddr = tproxy_laddr4(skb, laddr, iph->daddr);
	if (!lport)
		lport = hp->dest;

	/* UDP has no TCP_TIME_WAIT state, so we never enter here */
	if (sk && sk->sk_state == TCP_TIME_WAIT)
		/* reopening a TIME_WAIT connection needs special handling */
		sk = tproxy_handle_time_wait4(skb, laddr, lport, sk);
	else if (!sk)
		/* no, there's no established connection, check if
		 * there's a listener on the redirected addr/port */
		sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), iph->protocol,
					   iph->saddr, laddr,
					   hp->source, lport,
					   skb->dev, NFT_LOOKUP_LISTENER);

	/* NOTE: assign_sock consumes our sk reference */
	if (sk && nf_tproxy_assign_sock(skb, sk)) {
		/* This should be in a separate target, but we don't do multiple
		   targets on the same rule yet */
		skb->mark = (skb->mark & ~mark_mask) ^ mark_value;

		pr_debug("redirecting: proto %hhu %pI4:%hu -> %pI4:%hu, mark: %x\n",
			 iph->protocol, &iph->daddr, ntohs(hp->dest),
			 &laddr, ntohs(lport), skb->mark);
		return NF_ACCEPT;
	}

	pr_debug("no socket, dropping: proto %hhu %pI4:%hu -> %pI4:%hu, mark: %x\n",
		 iph->protocol, &iph->saddr, ntohs(hp->source),
		 &iph->daddr, ntohs(hp->dest), skb->mark);
	return NF_DROP;
}

static unsigned int
tproxy_tg4_v0(struct sk_buff *skb, const struct xt_action_param *par)
{
	const struct xt_tproxy_target_info *tgi = par->targinfo;

	return tproxy_tg4(skb, tgi->laddr, tgi->lport, tgi->mark_mask, tgi->mark_value);
}

static unsigned int
tproxy_tg4_v1(struct sk_buff *skb, const struct xt_action_param *par)
{
	const struct xt_tproxy_target_info_v1 *tgi = par->targinfo;

	return tproxy_tg4(skb, tgi->laddr.ip, tgi->lport, tgi->mark_mask, tgi->mark_value);
}

#ifdef XT_TPROXY_HAVE_IPV6

static inline const struct in6_addr *
tproxy_laddr6(struct sk_buff *skb, const struct in6_addr *user_laddr,
	      const struct in6_addr *daddr)
{
	struct inet6_dev *indev;
	struct inet6_ifaddr *ifa;
	struct in6_addr *laddr;

	if (!ipv6_addr_any(user_laddr))
		return user_laddr;
	laddr = NULL;

	rcu_read_lock();
	indev = __in6_dev_get(skb->dev);
	if (indev)
		list_for_each_entry(ifa, &indev->addr_list, if_list) {
			if (ifa->flags & (IFA_F_TENTATIVE | IFA_F_DEPRECATED))
				continue;

			laddr = &ifa->addr;
			break;
		}
	rcu_read_unlock();

	return laddr ? laddr : daddr;
}

/**
 * tproxy_handle_time_wait6() - handle IPv6 TCP TIME_WAIT reopen redirections
 * @skb:	The skb being processed.
 * @tproto:	Transport protocol.
 * @thoff:	Transport protocol header offset.
 * @par:	Iptables target parameters.
 * @sk:		The TIME_WAIT TCP socket found by the lookup.
 *
 * We have to handle SYN packets arriving to TIME_WAIT sockets
 * differently: instead of reopening the connection we should rather
 * redirect the new connection to the proxy if there's a listener
 * socket present.
 *
 * tproxy_handle_time_wait6() consumes the socket reference passed in.
 *
 * Returns the listener socket if there's one, the TIME_WAIT socket if
 * no such listener is found, or NULL if the TCP header is incomplete.
 */
static struct sock *
tproxy_handle_time_wait6(struct sk_buff *skb, int tproto, int thoff,
			 const struct xt_action_param *par,
			 struct sock *sk)
{
	const struct ipv6hdr *iph = ipv6_hdr(skb);
	struct tcphdr _hdr, *hp;
	const struct xt_tproxy_target_info_v1 *tgi = par->targinfo;

	hp = skb_header_pointer(skb, thoff, sizeof(_hdr), &_hdr);
	if (hp == NULL) {
		inet_twsk_put(inet_twsk(sk));
		return NULL;
	}

	if (hp->syn && !hp->rst && !hp->ack && !hp->fin) {
		/* SYN to a TIME_WAIT socket, we'd rather redirect it
		 * to a listener socket if there's one */
		struct sock *sk2;

		sk2 = nf_tproxy_get_sock_v6(dev_net(skb->dev), tproto,
					    &iph->saddr,
					    tproxy_laddr6(skb, &tgi->laddr.in6, &iph->daddr),
					    hp->source,
					    tgi->lport ? tgi->lport : hp->dest,
					    skb->dev, NFT_LOOKUP_LISTENER);
		if (sk2) {
			inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row);
			inet_twsk_put(inet_twsk(sk));
			sk = sk2;
		}
	}

	return sk;
}

static unsigned int
tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
{
	const struct ipv6hdr *iph = ipv6_hdr(skb);
	const struct xt_tproxy_target_info_v1 *tgi = par->targinfo;
	struct udphdr _hdr, *hp;
	struct sock *sk;
	const struct in6_addr *laddr;
	__be16 lport;
	int thoff;
	int tproto;

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

	hp = skb_header_pointer(skb, thoff, sizeof(_hdr), &_hdr);
	if (hp == NULL) {
		pr_debug("unable to grab transport header contents in IPv6 packet, dropping\n");
		return NF_DROP;
	}

	/* check if there's an ongoing connection on the packet
	 * addresses, this happens if the redirect already happened
	 * and the current packet belongs to an already established
	 * connection */
	sk = nf_tproxy_get_sock_v6(dev_net(skb->dev), tproto,
				   &iph->saddr, &iph->daddr,
				   hp->source, hp->dest,
				   par->in, NFT_LOOKUP_ESTABLISHED);

	laddr = tproxy_laddr6(skb, &tgi->laddr.in6, &iph->daddr);
	lport = tgi->lport ? tgi->lport : hp->dest;

	/* UDP has no TCP_TIME_WAIT state, so we never enter here */
	if (sk && sk->sk_state == TCP_TIME_WAIT)
		/* reopening a TIME_WAIT connection needs special handling */
		sk = tproxy_handle_time_wait6(skb, tproto, thoff, par, sk);
	else if (!sk)
		/* no there's no established connection, check if
		 * there's a listener on the redirected addr/port */
		sk = nf_tproxy_get_sock_v6(dev_net(skb->dev), tproto,
					   &iph->saddr, laddr,
					   hp->source, lport,
					   par->in, NFT_LOOKUP_LISTENER);

	/* NOTE: assign_sock consumes our sk reference */
	if (sk && nf_tproxy_assign_sock(skb, sk)) {
		/* This should be in a separate target, but we don't do multiple
		   targets on the same rule yet */
		skb->mark = (skb->mark & ~tgi->mark_mask) ^ tgi->mark_value;

		pr_debug("redirecting: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
			 tproto, &iph->saddr, ntohs(hp->source),
			 laddr, ntohs(lport), skb->mark);
		return NF_ACCEPT;
	}

	pr_debug("no socket, dropping: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
		 tproto, &iph->saddr, ntohs(hp->source),
		 &iph->daddr, ntohs(hp->dest), skb->mark);

	return NF_DROP;
}

static int tproxy_tg6_check(const struct xt_tgchk_param *par)
{
	const struct ip6t_ip6 *i = par->entryinfo;

	if ((i->proto == IPPROTO_TCP || i->proto == IPPROTO_UDP)
	    && !(i->flags & IP6T_INV_PROTO))
		return 0;

	pr_info("Can be used only in combination with "
		"either -p tcp or -p udp\n");
	return -EINVAL;
}
#endif

static int tproxy_tg4_check(const struct xt_tgchk_param *par)
{
	const struct ipt_ip *i = par->entryinfo;

	if ((i->proto == IPPROTO_TCP || i->proto == IPPROTO_UDP)
	    && !(i->invflags & IPT_INV_PROTO))
		return 0;

	pr_info("Can be used only in combination with "
		"either -p tcp or -p udp\n");
	return -EINVAL;
}

static struct xt_target tproxy_tg_reg[] __read_mostly = {
	{
		.name		= "TPROXY",
		.family		= NFPROTO_IPV4,
		.table		= "mangle",
		.target		= tproxy_tg4_v0,
		.revision	= 0,
		.targetsize	= sizeof(struct xt_tproxy_target_info),
		.checkentry	= tproxy_tg4_check,
		.hooks		= 1 << NF_INET_PRE_ROUTING,
		.me		= THIS_MODULE,
	},
	{
		.name		= "TPROXY",
		.family		= NFPROTO_IPV4,
		.table		= "mangle",
		.target		= tproxy_tg4_v1,
		.revision	= 1,
		.targetsize	= sizeof(struct xt_tproxy_target_info_v1),
		.checkentry	= tproxy_tg4_check,
		.hooks		= 1 << NF_INET_PRE_ROUTING,
		.me		= THIS_MODULE,
	},
#ifdef XT_TPROXY_HAVE_IPV6
	{
		.name		= "TPROXY",
		.family		= NFPROTO_IPV6,
		.table		= "mangle",
		.target		= tproxy_tg6_v1,
		.revision	= 1,
		.targetsize	= sizeof(struct xt_tproxy_target_info_v1),
		.checkentry	= tproxy_tg6_check,
		.hooks		= 1 << NF_INET_PRE_ROUTING,
		.me		= THIS_MODULE,
	},
#endif

};

static int __init tproxy_tg_init(void)
{
	nf_defrag_ipv4_enable();
#ifdef XT_TPROXY_HAVE_IPV6
	nf_defrag_ipv6_enable();
#endif

	return xt_register_targets(tproxy_tg_reg, ARRAY_SIZE(tproxy_tg_reg));
}

static void __exit tproxy_tg_exit(void)
{
	xt_unregister_targets(tproxy_tg_reg, ARRAY_SIZE(tproxy_tg_reg));
}

module_init(tproxy_tg_init);
module_exit(tproxy_tg_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Balazs Scheidler, Krisztian Kovacs");
MODULE_DESCRIPTION("Netfilter transparent proxy (TPROXY) target module.");
MODULE_ALIAS("ipt_TPROXY");
MODULE_ALIAS("ip6t_TPROXY");
Commit	Line	Data
e8439270 KK	1	/*
	2	* Transparent proxy support for Linux/iptables
	3	*
6ad78893	4	* Copyright (c) 2006-2010 BalaBit IT Ltd.
e8439270 KK	5	* Author: Balazs Scheidler, Krisztian Kovacs
	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License version 2 as
	9	* published by the Free Software Foundation.
	10	*
	11	*/
ff67e4e4	12	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
e8439270 KK	13	#include <linux/module.h>
	14	#include <linux/skbuff.h>
	15	#include <linux/ip.h>
	16	#include <net/checksum.h>
	17	#include <net/udp.h>
	18	#include <net/inet_sock.h>
cc6eb433	19	#include <linux/inetdevice.h>
e8439270 KK	20	#include <linux/netfilter/x_tables.h>
e8439270 KK	21	#include <linux/netfilter_ipv4/ip_tables.h>
e8439270 KK	22
e8439270 KK	23	#include <net/netfilter/ipv4/nf_defrag_ipv4.h>
f6318e55 KK	24
	25	#if defined(CONFIG_IP6_NF_IPTABLES) \|\| defined(CONFIG_IP6_NF_IPTABLES_MODULE)
	26	#define XT_TPROXY_HAVE_IPV6 1
cc6eb433 BS	27	#include <net/if_inet6.h>
	28	#include <net/addrconf.h>
	29	#include <linux/netfilter_ipv6/ip6_tables.h>
6ad78893	30	#include <net/netfilter/ipv6/nf_defrag_ipv6.h>
cc6eb433 BS	31	#endif
cc6eb433 BS	32
e8439270	33	#include <net/netfilter/nf_tproxy_core.h>
cc6eb433 BS	34	#include <linux/netfilter/xt_TPROXY.h>
	35
	36	static inline __be32
	37	tproxy_laddr4(struct sk_buff *skb, __be32 user_laddr, __be32 daddr)
	38	{
	39	struct in_device *indev;
	40	__be32 laddr;
	41
	42	if (user_laddr)
	43	return user_laddr;
	44
	45	laddr = 0;
	46	rcu_read_lock();
	47	indev = __in_dev_get_rcu(skb->dev);
	48	for_primary_ifa(indev) {
	49	laddr = ifa->ifa_local;
	50	break;
	51	} endfor_ifa(indev);
	52	rcu_read_unlock();
	53
	54	return laddr ? laddr : daddr;
	55	}
e8439270	56
106e4c26	57	/**
6ad78893	58	* tproxy_handle_time_wait4() - handle IPv4 TCP TIME_WAIT reopen redirections
106e4c26	59	* @skb: The skb being processed.
6ad78893 BS	60	* @laddr: IPv4 address to redirect to or zero.
6ad78893 BS	61	* @lport: TCP port to redirect to or zero.
106e4c26 BS	62	* @sk: The TIME_WAIT TCP socket found by the lookup.
	63	*
	64	* We have to handle SYN packets arriving to TIME_WAIT sockets
	65	* differently: instead of reopening the connection we should rather
	66	* redirect the new connection to the proxy if there's a listener
	67	* socket present.
	68	*
6ad78893	69	* tproxy_handle_time_wait4() consumes the socket reference passed in.
106e4c26 BS	70	*
	71	* Returns the listener socket if there's one, the TIME_WAIT socket if
	72	* no such listener is found, or NULL if the TCP header is incomplete.
	73	*/
	74	static struct sock *
6ad78893 BS	75	tproxy_handle_time_wait4(struct sk_buff *skb, __be32 laddr, __be16 lport,
6ad78893 BS	76	struct sock *sk)
106e4c26 BS	77	{
106e4c26 BS	78	const struct iphdr *iph = ip_hdr(skb);
106e4c26 BS	79	struct tcphdr _hdr, *hp;
	80
	81	hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr);
	82	if (hp == NULL) {
	83	inet_twsk_put(inet_twsk(sk));
	84	return NULL;
	85	}
	86
	87	if (hp->syn && !hp->rst && !hp->ack && !hp->fin) {
	88	/* SYN to a TIME_WAIT socket, we'd rather redirect it
	89	* to a listener socket if there's one */
	90	struct sock *sk2;
	91
	92	sk2 = nf_tproxy_get_sock_v4(dev_net(skb->dev), iph->protocol,
6ad78893 BS	93	iph->saddr, laddr ? laddr : iph->daddr,
	94	hp->source, lport ? lport : hp->dest,
	95	skb->dev, NFT_LOOKUP_LISTENER);
	96	if (sk2) {
	97	inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row);
	98	inet_twsk_put(inet_twsk(sk));
	99	sk = sk2;
	100	}
	101	}
	102
	103	return sk;
	104	}
	105
e8439270	106	static unsigned int
6ad78893 BS	107	tproxy_tg4(struct sk_buff *skb, __be32 laddr, __be16 lport,
6ad78893 BS	108	u_int32_t mark_mask, u_int32_t mark_value)
e8439270 KK	109	{
e8439270 KK	110	const struct iphdr *iph = ip_hdr(skb);
e8439270 KK	111	struct udphdr _hdr, *hp;
	112	struct sock *sk;
	113
	114	hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr);
	115	if (hp == NULL)
	116	return NF_DROP;
	117
6ad78893 BS	118	/* check if there's an ongoing connection on the packet
	119	* addresses, this happens if the redirect already happened
	120	* and the current packet belongs to an already established
	121	* connection */
e8439270	122	sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), iph->protocol,
106e4c26 BS	123	iph->saddr, iph->daddr,
106e4c26 BS	124	hp->source, hp->dest,
6ad78893	125	skb->dev, NFT_LOOKUP_ESTABLISHED);
106e4c26	126
cc6eb433 BS	127	laddr = tproxy_laddr4(skb, laddr, iph->daddr);
	128	if (!lport)
	129	lport = hp->dest;
	130
106e4c26 BS	131	/* UDP has no TCP_TIME_WAIT state, so we never enter here */
106e4c26 BS	132	if (sk && sk->sk_state == TCP_TIME_WAIT)
6ad78893 BS	133	/* reopening a TIME_WAIT connection needs special handling */
6ad78893 BS	134	sk = tproxy_handle_time_wait4(skb, laddr, lport, sk);
106e4c26	135	else if (!sk)
6ad78893 BS	136	/* no, there's no established connection, check if
6ad78893 BS	137	* there's a listener on the redirected addr/port */
106e4c26	138	sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), iph->protocol,
cc6eb433 BS	139	iph->saddr, laddr,
cc6eb433 BS	140	hp->source, lport,
6ad78893 BS	141	skb->dev, NFT_LOOKUP_LISTENER);
	142
	143	/* NOTE: assign_sock consumes our sk reference */
	144	if (sk && nf_tproxy_assign_sock(skb, sk)) {
	145	/* This should be in a separate target, but we don't do multiple
	146	targets on the same rule yet */
	147	skb->mark = (skb->mark & ~mark_mask) ^ mark_value;
	148
	149	pr_debug("redirecting: proto %hhu %pI4:%hu -> %pI4:%hu, mark: %x\n",
	150	iph->protocol, &iph->daddr, ntohs(hp->dest),
	151	&laddr, ntohs(lport), skb->mark);
	152	return NF_ACCEPT;
	153	}
	154
cc6eb433 BS	155	pr_debug("no socket, dropping: proto %hhu %pI4:%hu -> %pI4:%hu, mark: %x\n",
	156	iph->protocol, &iph->saddr, ntohs(hp->source),
	157	&iph->daddr, ntohs(hp->dest), skb->mark);
6ad78893 BS	158	return NF_DROP;
	159	}
	160
	161	static unsigned int
	162	tproxy_tg4_v0(struct sk_buff skb, const struct xt_action_param par)
	163	{
	164	const struct xt_tproxy_target_info *tgi = par->targinfo;
	165
	166	return tproxy_tg4(skb, tgi->laddr, tgi->lport, tgi->mark_mask, tgi->mark_value);
	167	}
	168
	169	static unsigned int
	170	tproxy_tg4_v1(struct sk_buff skb, const struct xt_action_param par)
	171	{
	172	const struct xt_tproxy_target_info_v1 *tgi = par->targinfo;
	173
	174	return tproxy_tg4(skb, tgi->laddr.ip, tgi->lport, tgi->mark_mask, tgi->mark_value);
	175	}
	176
f6318e55	177	#ifdef XT_TPROXY_HAVE_IPV6
cc6eb433 BS	178
	179	static inline const struct in6_addr *
	180	tproxy_laddr6(struct sk_buff skb, const struct in6_addr user_laddr,
	181	const struct in6_addr *daddr)
	182	{
	183	struct inet6_dev *indev;
	184	struct inet6_ifaddr *ifa;
	185	struct in6_addr *laddr;
	186
	187	if (!ipv6_addr_any(user_laddr))
	188	return user_laddr;
	189	laddr = NULL;
	190
	191	rcu_read_lock();
	192	indev = __in6_dev_get(skb->dev);
	193	if (indev)
	194	list_for_each_entry(ifa, &indev->addr_list, if_list) {
	195	if (ifa->flags & (IFA_F_TENTATIVE \| IFA_F_DEPRECATED))
	196	continue;
	197
	198	laddr = &ifa->addr;
	199	break;
	200	}
	201	rcu_read_unlock();
	202
	203	return laddr ? laddr : daddr;
	204	}
	205
	206	/**
	207	* tproxy_handle_time_wait6() - handle IPv6 TCP TIME_WAIT reopen redirections
	208	* @skb: The skb being processed.
	209	* @tproto: Transport protocol.
	210	* @thoff: Transport protocol header offset.
	211	* @par: Iptables target parameters.
	212	* @sk: The TIME_WAIT TCP socket found by the lookup.
	213	*
	214	* We have to handle SYN packets arriving to TIME_WAIT sockets
	215	* differently: instead of reopening the connection we should rather
	216	* redirect the new connection to the proxy if there's a listener
	217	* socket present.
	218	*
	219	* tproxy_handle_time_wait6() consumes the socket reference passed in.
	220	*
	221	* Returns the listener socket if there's one, the TIME_WAIT socket if
	222	* no such listener is found, or NULL if the TCP header is incomplete.
	223	*/
	224	static struct sock *
	225	tproxy_handle_time_wait6(struct sk_buff *skb, int tproto, int thoff,
	226	const struct xt_action_param *par,
	227	struct sock *sk)
	228	{
	229	const struct ipv6hdr *iph = ipv6_hdr(skb);
	230	struct tcphdr _hdr, *hp;
	231	const struct xt_tproxy_target_info_v1 *tgi = par->targinfo;
	232
	233	hp = skb_header_pointer(skb, thoff, sizeof(_hdr), &_hdr);
	234	if (hp == NULL) {
	235	inet_twsk_put(inet_twsk(sk));
	236	return NULL;
	237	}
	238
	239	if (hp->syn && !hp->rst && !hp->ack && !hp->fin) {
	240	/* SYN to a TIME_WAIT socket, we'd rather redirect it
	241	* to a listener socket if there's one */
242	struct sock *sk2;
243
244	sk2 = nf_tproxy_get_sock_v6(dev_net(skb->dev), tproto,
245	&iph->saddr,
246	tproxy_laddr6(skb, &tgi->laddr.in6, &iph->daddr),
247	hp->source,
248	tgi->lport ? tgi->lport : hp->dest,
249	skb->dev, NFT_LOOKUP_LISTENER);
250	if (sk2) {
251	inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row);
252	inet_twsk_put(inet_twsk(sk));
253	sk = sk2;
254	}
255	}
256
257	return sk;
258	}
259
6ad78893 BS	260	static unsigned int
	261	tproxy_tg6_v1(struct sk_buff skb, const struct xt_action_param par)
	262	{
	263	const struct ipv6hdr *iph = ipv6_hdr(skb);
	264	const struct xt_tproxy_target_info_v1 *tgi = par->targinfo;
	265	struct udphdr _hdr, *hp;
	266	struct sock *sk;
cc6eb433 BS	267	const struct in6_addr *laddr;
cc6eb433 BS	268	__be16 lport;
6ad78893 BS	269	int thoff;
	270	int tproto;
	271
	272	tproto = ipv6_find_hdr(skb, &thoff, -1, NULL);
	273	if (tproto < 0) {
	274	pr_debug("unable to find transport header in IPv6 packet, dropping\n");
	275	return NF_DROP;
	276	}
	277
	278	hp = skb_header_pointer(skb, thoff, sizeof(_hdr), &_hdr);
	279	if (hp == NULL) {
	280	pr_debug("unable to grab transport header contents in IPv6 packet, dropping\n");
	281	return NF_DROP;
	282	}
	283
	284	/* check if there's an ongoing connection on the packet
	285	* addresses, this happens if the redirect already happened
	286	* and the current packet belongs to an already established
	287	* connection */
	288	sk = nf_tproxy_get_sock_v6(dev_net(skb->dev), tproto,
	289	&iph->saddr, &iph->daddr,
	290	hp->source, hp->dest,
	291	par->in, NFT_LOOKUP_ESTABLISHED);
	292
cc6eb433 BS	293	laddr = tproxy_laddr6(skb, &tgi->laddr.in6, &iph->daddr);
	294	lport = tgi->lport ? tgi->lport : hp->dest;
	295
6ad78893 BS	296	/* UDP has no TCP_TIME_WAIT state, so we never enter here */
	297	if (sk && sk->sk_state == TCP_TIME_WAIT)
	298	/* reopening a TIME_WAIT connection needs special handling */
	299	sk = tproxy_handle_time_wait6(skb, tproto, thoff, par, sk);
	300	else if (!sk)
	301	/* no there's no established connection, check if
	302	* there's a listener on the redirected addr/port */
	303	sk = nf_tproxy_get_sock_v6(dev_net(skb->dev), tproto,
cc6eb433 BS	304	&iph->saddr, laddr,
cc6eb433 BS	305	hp->source, lport,
106e4c26	306	par->in, NFT_LOOKUP_LISTENER);
e8439270 KK	307
	308	/* NOTE: assign_sock consumes our sk reference */
	309	if (sk && nf_tproxy_assign_sock(skb, sk)) {
	310	/* This should be in a separate target, but we don't do multiple
	311	targets on the same rule yet */
	312	skb->mark = (skb->mark & ~tgi->mark_mask) ^ tgi->mark_value;
	313
6ad78893	314	pr_debug("redirecting: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
cc6eb433 BS	315	tproto, &iph->saddr, ntohs(hp->source),
cc6eb433 BS	316	laddr, ntohs(lport), skb->mark);
e8439270 KK	317	return NF_ACCEPT;
	318	}
	319
6ad78893	320	pr_debug("no socket, dropping: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
cc6eb433 BS	321	tproto, &iph->saddr, ntohs(hp->source),
	322	&iph->daddr, ntohs(hp->dest), skb->mark);
	323
e8439270 KK	324	return NF_DROP;
	325	}
	326
6ad78893 BS	327	static int tproxy_tg6_check(const struct xt_tgchk_param *par)
	328	{
	329	const struct ip6t_ip6 *i = par->entryinfo;
	330
	331	if ((i->proto == IPPROTO_TCP \|\| i->proto == IPPROTO_UDP)
	332	&& !(i->flags & IP6T_INV_PROTO))
	333	return 0;
	334
	335	pr_info("Can be used only in combination with "
	336	"either -p tcp or -p udp\n");
	337	return -EINVAL;
	338	}
	339	#endif
	340
	341	static int tproxy_tg4_check(const struct xt_tgchk_param *par)
e8439270	342	{
af5d6dc2	343	const struct ipt_ip *i = par->entryinfo;
e8439270 KK	344
	345	if ((i->proto == IPPROTO_TCP \|\| i->proto == IPPROTO_UDP)
	346	&& !(i->invflags & IPT_INV_PROTO))
d6b00a53	347	return 0;
e8439270	348
ff67e4e4	349	pr_info("Can be used only in combination with "
e8439270	350	"either -p tcp or -p udp\n");
d6b00a53	351	return -EINVAL;
e8439270 KK	352	}
e8439270 KK	353
6ad78893 BS	354	static struct xt_target tproxy_tg_reg[] __read_mostly = {
	355	{
	356	.name = "TPROXY",
	357	.family = NFPROTO_IPV4,
	358	.table = "mangle",
	359	.target = tproxy_tg4_v0,
	360	.revision = 0,
	361	.targetsize = sizeof(struct xt_tproxy_target_info),
	362	.checkentry = tproxy_tg4_check,
	363	.hooks = 1 << NF_INET_PRE_ROUTING,
	364	.me = THIS_MODULE,
	365	},
	366	{
	367	.name = "TPROXY",
	368	.family = NFPROTO_IPV4,
	369	.table = "mangle",
	370	.target = tproxy_tg4_v1,
	371	.revision = 1,
	372	.targetsize = sizeof(struct xt_tproxy_target_info_v1),
	373	.checkentry = tproxy_tg4_check,
	374	.hooks = 1 << NF_INET_PRE_ROUTING,
	375	.me = THIS_MODULE,
	376	},
f6318e55	377	#ifdef XT_TPROXY_HAVE_IPV6
6ad78893 BS	378	{
	379	.name = "TPROXY",
	380	.family = NFPROTO_IPV6,
	381	.table = "mangle",
	382	.target = tproxy_tg6_v1,
	383	.revision = 1,
	384	.targetsize = sizeof(struct xt_tproxy_target_info_v1),
	385	.checkentry = tproxy_tg6_check,
	386	.hooks = 1 << NF_INET_PRE_ROUTING,
	387	.me = THIS_MODULE,
	388	},
	389	#endif
	390
e8439270 KK	391	};
	392
	393	static int __init tproxy_tg_init(void)
	394	{
	395	nf_defrag_ipv4_enable();
f6318e55	396	#ifdef XT_TPROXY_HAVE_IPV6
6ad78893 BS	397	nf_defrag_ipv6_enable();
	398	#endif
	399
	400	return xt_register_targets(tproxy_tg_reg, ARRAY_SIZE(tproxy_tg_reg));
e8439270 KK	401	}
	402
	403	static void __exit tproxy_tg_exit(void)
	404	{
6ad78893	405	xt_unregister_targets(tproxy_tg_reg, ARRAY_SIZE(tproxy_tg_reg));
e8439270 KK	406	}
	407
	408	module_init(tproxy_tg_init);
	409	module_exit(tproxy_tg_exit);
	410	MODULE_LICENSE("GPL");
6ad78893	411	MODULE_AUTHOR("Balazs Scheidler, Krisztian Kovacs");
e8439270 KK	412	MODULE_DESCRIPTION("Netfilter transparent proxy (TPROXY) target module.");
e8439270 KK	413	MODULE_ALIAS("ipt_TPROXY");
6ad78893	414	MODULE_ALIAS("ip6t_TPROXY");