[deliverable/linux.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_IPV6) || defined(CONFIG_IPV6_MODULE)
#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);
}

#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)

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,
	},
#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
	{
		.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();
#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
	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>
cc6eb433 BS	24	#if defined(CONFIG_IPV6) \|\| defined(CONFIG_IPV6_MODULE)
	25	#include <net/if_inet6.h>
	26	#include <net/addrconf.h>
	27	#include <linux/netfilter_ipv6/ip6_tables.h>
6ad78893	28	#include <net/netfilter/ipv6/nf_defrag_ipv6.h>
cc6eb433 BS	29	#endif
cc6eb433 BS	30
e8439270	31	#include <net/netfilter/nf_tproxy_core.h>
cc6eb433 BS	32	#include <linux/netfilter/xt_TPROXY.h>
	33
	34	static inline __be32
	35	tproxy_laddr4(struct sk_buff *skb, __be32 user_laddr, __be32 daddr)
	36	{
	37	struct in_device *indev;
	38	__be32 laddr;
	39
	40	if (user_laddr)
	41	return user_laddr;
	42
	43	laddr = 0;
	44	rcu_read_lock();
	45	indev = __in_dev_get_rcu(skb->dev);
	46	for_primary_ifa(indev) {
	47	laddr = ifa->ifa_local;
	48	break;
	49	} endfor_ifa(indev);
	50	rcu_read_unlock();
	51
	52	return laddr ? laddr : daddr;
	53	}
e8439270	54
106e4c26	55	/**
6ad78893	56	* tproxy_handle_time_wait4() - handle IPv4 TCP TIME_WAIT reopen redirections
106e4c26	57	* @skb: The skb being processed.
6ad78893 BS	58	* @laddr: IPv4 address to redirect to or zero.
6ad78893 BS	59	* @lport: TCP port to redirect to or zero.
106e4c26 BS	60	* @sk: The TIME_WAIT TCP socket found by the lookup.
	61	*
	62	* We have to handle SYN packets arriving to TIME_WAIT sockets
	63	* differently: instead of reopening the connection we should rather
	64	* redirect the new connection to the proxy if there's a listener
	65	* socket present.
	66	*
6ad78893	67	* tproxy_handle_time_wait4() consumes the socket reference passed in.
106e4c26 BS	68	*
	69	* Returns the listener socket if there's one, the TIME_WAIT socket if
	70	* no such listener is found, or NULL if the TCP header is incomplete.
	71	*/
	72	static struct sock *
6ad78893 BS	73	tproxy_handle_time_wait4(struct sk_buff *skb, __be32 laddr, __be16 lport,
6ad78893 BS	74	struct sock *sk)
106e4c26 BS	75	{
106e4c26 BS	76	const struct iphdr *iph = ip_hdr(skb);
106e4c26 BS	77	struct tcphdr _hdr, *hp;
	78
	79	hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr);
	80	if (hp == NULL) {
	81	inet_twsk_put(inet_twsk(sk));
	82	return NULL;
	83	}
	84
	85	if (hp->syn && !hp->rst && !hp->ack && !hp->fin) {
	86	/* SYN to a TIME_WAIT socket, we'd rather redirect it
	87	* to a listener socket if there's one */
	88	struct sock *sk2;
	89
	90	sk2 = nf_tproxy_get_sock_v4(dev_net(skb->dev), iph->protocol,
6ad78893 BS	91	iph->saddr, laddr ? laddr : iph->daddr,
	92	hp->source, lport ? lport : hp->dest,
	93	skb->dev, NFT_LOOKUP_LISTENER);
	94	if (sk2) {
	95	inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row);
	96	inet_twsk_put(inet_twsk(sk));
	97	sk = sk2;
	98	}
	99	}
	100
	101	return sk;
	102	}
	103
e8439270	104	static unsigned int
6ad78893 BS	105	tproxy_tg4(struct sk_buff *skb, __be32 laddr, __be16 lport,
6ad78893 BS	106	u_int32_t mark_mask, u_int32_t mark_value)
e8439270 KK	107	{
e8439270 KK	108	const struct iphdr *iph = ip_hdr(skb);
e8439270 KK	109	struct udphdr _hdr, *hp;
	110	struct sock *sk;
	111
	112	hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr);
	113	if (hp == NULL)
	114	return NF_DROP;
	115
6ad78893 BS	116	/* check if there's an ongoing connection on the packet
	117	* addresses, this happens if the redirect already happened
	118	* and the current packet belongs to an already established
	119	* connection */
e8439270	120	sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), iph->protocol,
106e4c26 BS	121	iph->saddr, iph->daddr,
106e4c26 BS	122	hp->source, hp->dest,
6ad78893	123	skb->dev, NFT_LOOKUP_ESTABLISHED);
106e4c26	124
cc6eb433 BS	125	laddr = tproxy_laddr4(skb, laddr, iph->daddr);
	126	if (!lport)
	127	lport = hp->dest;
	128
106e4c26 BS	129	/* UDP has no TCP_TIME_WAIT state, so we never enter here */
106e4c26 BS	130	if (sk && sk->sk_state == TCP_TIME_WAIT)
6ad78893 BS	131	/* reopening a TIME_WAIT connection needs special handling */
6ad78893 BS	132	sk = tproxy_handle_time_wait4(skb, laddr, lport, sk);
106e4c26	133	else if (!sk)
6ad78893 BS	134	/* no, there's no established connection, check if
6ad78893 BS	135	* there's a listener on the redirected addr/port */
106e4c26	136	sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), iph->protocol,
cc6eb433 BS	137	iph->saddr, laddr,
cc6eb433 BS	138	hp->source, lport,
6ad78893 BS	139	skb->dev, NFT_LOOKUP_LISTENER);
	140
	141	/* NOTE: assign_sock consumes our sk reference */
	142	if (sk && nf_tproxy_assign_sock(skb, sk)) {
	143	/* This should be in a separate target, but we don't do multiple
	144	targets on the same rule yet */
	145	skb->mark = (skb->mark & ~mark_mask) ^ mark_value;
	146
	147	pr_debug("redirecting: proto %hhu %pI4:%hu -> %pI4:%hu, mark: %x\n",
	148	iph->protocol, &iph->daddr, ntohs(hp->dest),
	149	&laddr, ntohs(lport), skb->mark);
	150	return NF_ACCEPT;
	151	}
	152
cc6eb433 BS	153	pr_debug("no socket, dropping: proto %hhu %pI4:%hu -> %pI4:%hu, mark: %x\n",
	154	iph->protocol, &iph->saddr, ntohs(hp->source),
	155	&iph->daddr, ntohs(hp->dest), skb->mark);
6ad78893 BS	156	return NF_DROP;
	157	}
	158
	159	static unsigned int
	160	tproxy_tg4_v0(struct sk_buff skb, const struct xt_action_param par)
	161	{
	162	const struct xt_tproxy_target_info *tgi = par->targinfo;
	163
	164	return tproxy_tg4(skb, tgi->laddr, tgi->lport, tgi->mark_mask, tgi->mark_value);
	165	}
	166
	167	static unsigned int
	168	tproxy_tg4_v1(struct sk_buff skb, const struct xt_action_param par)
	169	{
	170	const struct xt_tproxy_target_info_v1 *tgi = par->targinfo;
	171
	172	return tproxy_tg4(skb, tgi->laddr.ip, tgi->lport, tgi->mark_mask, tgi->mark_value);
	173	}
	174
	175	#if defined(CONFIG_IPV6) \|\| defined(CONFIG_IPV6_MODULE)
cc6eb433 BS	176
	177	static inline const struct in6_addr *
	178	tproxy_laddr6(struct sk_buff skb, const struct in6_addr user_laddr,
	179	const struct in6_addr *daddr)
	180	{
	181	struct inet6_dev *indev;
	182	struct inet6_ifaddr *ifa;
	183	struct in6_addr *laddr;
	184
	185	if (!ipv6_addr_any(user_laddr))
	186	return user_laddr;
	187	laddr = NULL;
	188
	189	rcu_read_lock();
	190	indev = __in6_dev_get(skb->dev);
	191	if (indev)
	192	list_for_each_entry(ifa, &indev->addr_list, if_list) {
	193	if (ifa->flags & (IFA_F_TENTATIVE \| IFA_F_DEPRECATED))
	194	continue;
	195
	196	laddr = &ifa->addr;
	197	break;
	198	}
	199	rcu_read_unlock();
	200
	201	return laddr ? laddr : daddr;
	202	}
	203
	204	/**
	205	* tproxy_handle_time_wait6() - handle IPv6 TCP TIME_WAIT reopen redirections
	206	* @skb: The skb being processed.
	207	* @tproto: Transport protocol.
	208	* @thoff: Transport protocol header offset.
	209	* @par: Iptables target parameters.
	210	* @sk: The TIME_WAIT TCP socket found by the lookup.
	211	*
	212	* We have to handle SYN packets arriving to TIME_WAIT sockets
	213	* differently: instead of reopening the connection we should rather
	214	* redirect the new connection to the proxy if there's a listener
	215	* socket present.
	216	*
	217	* tproxy_handle_time_wait6() consumes the socket reference passed in.
	218	*
	219	* Returns the listener socket if there's one, the TIME_WAIT socket if
	220	* no such listener is found, or NULL if the TCP header is incomplete.
	221	*/
	222	static struct sock *
	223	tproxy_handle_time_wait6(struct sk_buff *skb, int tproto, int thoff,
	224	const struct xt_action_param *par,
	225	struct sock *sk)
	226	{
	227	const struct ipv6hdr *iph = ipv6_hdr(skb);
	228	struct tcphdr _hdr, *hp;
	229	const struct xt_tproxy_target_info_v1 *tgi = par->targinfo;
	230
	231	hp = skb_header_pointer(skb, thoff, sizeof(_hdr), &_hdr);
	232	if (hp == NULL) {
	233	inet_twsk_put(inet_twsk(sk));
	234	return NULL;
	235	}
	236
	237	if (hp->syn && !hp->rst && !hp->ack && !hp->fin) {
	238	/* SYN to a TIME_WAIT socket, we'd rather redirect it
	239	* to a listener socket if there's one */
240	struct sock *sk2;
241
242	sk2 = nf_tproxy_get_sock_v6(dev_net(skb->dev), tproto,
243	&iph->saddr,
244	tproxy_laddr6(skb, &tgi->laddr.in6, &iph->daddr),
245	hp->source,
246	tgi->lport ? tgi->lport : hp->dest,
247	skb->dev, NFT_LOOKUP_LISTENER);
248	if (sk2) {
249	inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row);
250	inet_twsk_put(inet_twsk(sk));
251	sk = sk2;
252	}
253	}
254
255	return sk;
256	}
257
6ad78893 BS	258	static unsigned int
	259	tproxy_tg6_v1(struct sk_buff skb, const struct xt_action_param par)
	260	{
	261	const struct ipv6hdr *iph = ipv6_hdr(skb);
	262	const struct xt_tproxy_target_info_v1 *tgi = par->targinfo;
	263	struct udphdr _hdr, *hp;
	264	struct sock *sk;
cc6eb433 BS	265	const struct in6_addr *laddr;
cc6eb433 BS	266	__be16 lport;
6ad78893 BS	267	int thoff;
	268	int tproto;
	269
	270	tproto = ipv6_find_hdr(skb, &thoff, -1, NULL);
	271	if (tproto < 0) {
	272	pr_debug("unable to find transport header in IPv6 packet, dropping\n");
	273	return NF_DROP;
	274	}
	275
	276	hp = skb_header_pointer(skb, thoff, sizeof(_hdr), &_hdr);
	277	if (hp == NULL) {
	278	pr_debug("unable to grab transport header contents in IPv6 packet, dropping\n");
	279	return NF_DROP;
	280	}
	281
	282	/* check if there's an ongoing connection on the packet
	283	* addresses, this happens if the redirect already happened
	284	* and the current packet belongs to an already established
	285	* connection */
	286	sk = nf_tproxy_get_sock_v6(dev_net(skb->dev), tproto,
	287	&iph->saddr, &iph->daddr,
	288	hp->source, hp->dest,
	289	par->in, NFT_LOOKUP_ESTABLISHED);
	290
cc6eb433 BS	291	laddr = tproxy_laddr6(skb, &tgi->laddr.in6, &iph->daddr);
	292	lport = tgi->lport ? tgi->lport : hp->dest;
	293
6ad78893 BS	294	/* UDP has no TCP_TIME_WAIT state, so we never enter here */
	295	if (sk && sk->sk_state == TCP_TIME_WAIT)
	296	/* reopening a TIME_WAIT connection needs special handling */
	297	sk = tproxy_handle_time_wait6(skb, tproto, thoff, par, sk);
	298	else if (!sk)
	299	/* no there's no established connection, check if
	300	* there's a listener on the redirected addr/port */
	301	sk = nf_tproxy_get_sock_v6(dev_net(skb->dev), tproto,
cc6eb433 BS	302	&iph->saddr, laddr,
cc6eb433 BS	303	hp->source, lport,
106e4c26	304	par->in, NFT_LOOKUP_LISTENER);
e8439270 KK	305
	306	/* NOTE: assign_sock consumes our sk reference */
	307	if (sk && nf_tproxy_assign_sock(skb, sk)) {
	308	/* This should be in a separate target, but we don't do multiple
	309	targets on the same rule yet */
	310	skb->mark = (skb->mark & ~tgi->mark_mask) ^ tgi->mark_value;
	311
6ad78893	312	pr_debug("redirecting: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
cc6eb433 BS	313	tproto, &iph->saddr, ntohs(hp->source),
cc6eb433 BS	314	laddr, ntohs(lport), skb->mark);
e8439270 KK	315	return NF_ACCEPT;
	316	}
	317
6ad78893	318	pr_debug("no socket, dropping: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
cc6eb433 BS	319	tproto, &iph->saddr, ntohs(hp->source),
	320	&iph->daddr, ntohs(hp->dest), skb->mark);
	321
e8439270 KK	322	return NF_DROP;
	323	}
	324
6ad78893 BS	325	static int tproxy_tg6_check(const struct xt_tgchk_param *par)
	326	{
	327	const struct ip6t_ip6 *i = par->entryinfo;
	328
	329	if ((i->proto == IPPROTO_TCP \|\| i->proto == IPPROTO_UDP)
	330	&& !(i->flags & IP6T_INV_PROTO))
	331	return 0;
	332
	333	pr_info("Can be used only in combination with "
	334	"either -p tcp or -p udp\n");
	335	return -EINVAL;
	336	}
	337	#endif
	338
	339	static int tproxy_tg4_check(const struct xt_tgchk_param *par)
e8439270	340	{
af5d6dc2	341	const struct ipt_ip *i = par->entryinfo;
e8439270 KK	342
	343	if ((i->proto == IPPROTO_TCP \|\| i->proto == IPPROTO_UDP)
	344	&& !(i->invflags & IPT_INV_PROTO))
d6b00a53	345	return 0;
e8439270	346
ff67e4e4	347	pr_info("Can be used only in combination with "
e8439270	348	"either -p tcp or -p udp\n");
d6b00a53	349	return -EINVAL;
e8439270 KK	350	}
e8439270 KK	351
6ad78893 BS	352	static struct xt_target tproxy_tg_reg[] __read_mostly = {
	353	{
	354	.name = "TPROXY",
	355	.family = NFPROTO_IPV4,
	356	.table = "mangle",
	357	.target = tproxy_tg4_v0,
	358	.revision = 0,
	359	.targetsize = sizeof(struct xt_tproxy_target_info),
	360	.checkentry = tproxy_tg4_check,
	361	.hooks = 1 << NF_INET_PRE_ROUTING,
	362	.me = THIS_MODULE,
	363	},
	364	{
	365	.name = "TPROXY",
	366	.family = NFPROTO_IPV4,
	367	.table = "mangle",
	368	.target = tproxy_tg4_v1,
	369	.revision = 1,
	370	.targetsize = sizeof(struct xt_tproxy_target_info_v1),
	371	.checkentry = tproxy_tg4_check,
	372	.hooks = 1 << NF_INET_PRE_ROUTING,
	373	.me = THIS_MODULE,
	374	},
	375	#if defined(CONFIG_IPV6) \|\| defined(CONFIG_IPV6_MODULE)
	376	{
	377	.name = "TPROXY",
	378	.family = NFPROTO_IPV6,
	379	.table = "mangle",
	380	.target = tproxy_tg6_v1,
	381	.revision = 1,
	382	.targetsize = sizeof(struct xt_tproxy_target_info_v1),
	383	.checkentry = tproxy_tg6_check,
	384	.hooks = 1 << NF_INET_PRE_ROUTING,
	385	.me = THIS_MODULE,
	386	},
	387	#endif
	388
e8439270 KK	389	};
	390
	391	static int __init tproxy_tg_init(void)
	392	{
	393	nf_defrag_ipv4_enable();
6ad78893 BS	394	#if defined(CONFIG_IPV6) \|\| defined(CONFIG_IPV6_MODULE)
	395	nf_defrag_ipv6_enable();
	396	#endif
	397
	398	return xt_register_targets(tproxy_tg_reg, ARRAY_SIZE(tproxy_tg_reg));
e8439270 KK	399	}
	400
	401	static void __exit tproxy_tg_exit(void)
	402	{
6ad78893	403	xt_unregister_targets(tproxy_tg_reg, ARRAY_SIZE(tproxy_tg_reg));
e8439270 KK	404	}
	405
	406	module_init(tproxy_tg_init);
	407	module_exit(tproxy_tg_exit);
	408	MODULE_LICENSE("GPL");
6ad78893	409	MODULE_AUTHOR("Balazs Scheidler, Krisztian Kovacs");
e8439270 KK	410	MODULE_DESCRIPTION("Netfilter transparent proxy (TPROXY) target module.");
e8439270 KK	411	MODULE_ALIAS("ipt_TPROXY");
6ad78893	412	MODULE_ALIAS("ip6t_TPROXY");