[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 IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
#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 bool tproxy_sk_is_transparent(struct sock *sk)
{
	if (sk->sk_state != TCP_TIME_WAIT) {
		if (inet_sk(sk)->transparent)
			return true;
		sock_put(sk);
	} else {
		if (inet_twsk(sk)->tw_transparent)
			return true;
		inet_twsk_put(inet_twsk(sk));
	}
	return false;
}

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;
}

/* assign a socket to the skb -- consumes sk */
static void
nf_tproxy_assign_sock(struct sk_buff *skb, struct sock *sk)
{
	skb_orphan(skb);
	skb->sk = sk;
	skb->destructor = sock_edemux;
}

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 && tproxy_sk_is_transparent(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);

		nf_tproxy_assign_sock(skb, sk);
		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 = 0;
	int tproto;

	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;
	}

	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 && tproxy_sk_is_transparent(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);

		nf_tproxy_assign_sock(skb, sk);
		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	24
c0cd1156	25	#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
f6318e55	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>
cc6eb433 BS	35
d503b30b FW	36	static bool tproxy_sk_is_transparent(struct sock *sk)
	37	{
	38	if (sk->sk_state != TCP_TIME_WAIT) {
	39	if (inet_sk(sk)->transparent)
	40	return true;
	41	sock_put(sk);
	42	} else {
	43	if (inet_twsk(sk)->tw_transparent)
	44	return true;
	45	inet_twsk_put(inet_twsk(sk));
	46	}
	47	return false;
	48	}
	49
cc6eb433 BS	50	static inline __be32
	51	tproxy_laddr4(struct sk_buff *skb, __be32 user_laddr, __be32 daddr)
	52	{
	53	struct in_device *indev;
	54	__be32 laddr;
	55
	56	if (user_laddr)
	57	return user_laddr;
	58
	59	laddr = 0;
	60	rcu_read_lock();
	61	indev = __in_dev_get_rcu(skb->dev);
	62	for_primary_ifa(indev) {
	63	laddr = ifa->ifa_local;
	64	break;
	65	} endfor_ifa(indev);
	66	rcu_read_unlock();
	67
	68	return laddr ? laddr : daddr;
	69	}
e8439270	70
106e4c26	71	/**
2c53040f	72	* tproxy_handle_time_wait4 - handle IPv4 TCP TIME_WAIT reopen redirections
106e4c26	73	* @skb: The skb being processed.
6ad78893 BS	74	* @laddr: IPv4 address to redirect to or zero.
6ad78893 BS	75	* @lport: TCP port to redirect to or zero.
106e4c26 BS	76	* @sk: The TIME_WAIT TCP socket found by the lookup.
	77	*
	78	* We have to handle SYN packets arriving to TIME_WAIT sockets
	79	* differently: instead of reopening the connection we should rather
	80	* redirect the new connection to the proxy if there's a listener
	81	* socket present.
	82	*
6ad78893	83	* tproxy_handle_time_wait4() consumes the socket reference passed in.
106e4c26 BS	84	*
	85	* Returns the listener socket if there's one, the TIME_WAIT socket if
	86	* no such listener is found, or NULL if the TCP header is incomplete.
	87	*/
	88	static struct sock *
6ad78893 BS	89	tproxy_handle_time_wait4(struct sk_buff *skb, __be32 laddr, __be16 lport,
6ad78893 BS	90	struct sock *sk)
106e4c26 BS	91	{
106e4c26 BS	92	const struct iphdr *iph = ip_hdr(skb);
106e4c26 BS	93	struct tcphdr _hdr, *hp;
	94
	95	hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr);
	96	if (hp == NULL) {
	97	inet_twsk_put(inet_twsk(sk));
	98	return NULL;
	99	}
	100
	101	if (hp->syn && !hp->rst && !hp->ack && !hp->fin) {
	102	/* SYN to a TIME_WAIT socket, we'd rather redirect it
	103	* to a listener socket if there's one */
	104	struct sock *sk2;
	105
	106	sk2 = nf_tproxy_get_sock_v4(dev_net(skb->dev), iph->protocol,
6ad78893 BS	107	iph->saddr, laddr ? laddr : iph->daddr,
	108	hp->source, lport ? lport : hp->dest,
	109	skb->dev, NFT_LOOKUP_LISTENER);
	110	if (sk2) {
	111	inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row);
	112	inet_twsk_put(inet_twsk(sk));
	113	sk = sk2;
	114	}
	115	}
	116
	117	return sk;
	118	}
	119
fd158d79 FW	120	/* assign a socket to the skb -- consumes sk */
	121	static void
	122	nf_tproxy_assign_sock(struct sk_buff skb, struct sock sk)
	123	{
	124	skb_orphan(skb);
	125	skb->sk = sk;
	126	skb->destructor = sock_edemux;
	127	}
	128
e8439270	129	static unsigned int
6ad78893 BS	130	tproxy_tg4(struct sk_buff *skb, __be32 laddr, __be16 lport,
6ad78893 BS	131	u_int32_t mark_mask, u_int32_t mark_value)
e8439270 KK	132	{
e8439270 KK	133	const struct iphdr *iph = ip_hdr(skb);
e8439270 KK	134	struct udphdr _hdr, *hp;
	135	struct sock *sk;
	136
	137	hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr);
	138	if (hp == NULL)
	139	return NF_DROP;
	140
6ad78893 BS	141	/* check if there's an ongoing connection on the packet
	142	* addresses, this happens if the redirect already happened
	143	* and the current packet belongs to an already established
	144	* connection */
e8439270	145	sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), iph->protocol,
106e4c26 BS	146	iph->saddr, iph->daddr,
106e4c26 BS	147	hp->source, hp->dest,
6ad78893	148	skb->dev, NFT_LOOKUP_ESTABLISHED);
106e4c26	149
cc6eb433 BS	150	laddr = tproxy_laddr4(skb, laddr, iph->daddr);
	151	if (!lport)
	152	lport = hp->dest;
	153
106e4c26 BS	154	/* UDP has no TCP_TIME_WAIT state, so we never enter here */
106e4c26 BS	155	if (sk && sk->sk_state == TCP_TIME_WAIT)
6ad78893 BS	156	/* reopening a TIME_WAIT connection needs special handling */
6ad78893 BS	157	sk = tproxy_handle_time_wait4(skb, laddr, lport, sk);
106e4c26	158	else if (!sk)
6ad78893 BS	159	/* no, there's no established connection, check if
6ad78893 BS	160	* there's a listener on the redirected addr/port */
106e4c26	161	sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), iph->protocol,
cc6eb433 BS	162	iph->saddr, laddr,
cc6eb433 BS	163	hp->source, lport,
6ad78893 BS	164	skb->dev, NFT_LOOKUP_LISTENER);
	165
	166	/* NOTE: assign_sock consumes our sk reference */
d503b30b	167	if (sk && tproxy_sk_is_transparent(sk)) {
6ad78893 BS	168	/* This should be in a separate target, but we don't do multiple
	169	targets on the same rule yet */
	170	skb->mark = (skb->mark & ~mark_mask) ^ mark_value;
	171
	172	pr_debug("redirecting: proto %hhu %pI4:%hu -> %pI4:%hu, mark: %x\n",
	173	iph->protocol, &iph->daddr, ntohs(hp->dest),
	174	&laddr, ntohs(lport), skb->mark);
d503b30b FW	175
d503b30b FW	176	nf_tproxy_assign_sock(skb, sk);
6ad78893 BS	177	return NF_ACCEPT;
	178	}
	179
cc6eb433 BS	180	pr_debug("no socket, dropping: proto %hhu %pI4:%hu -> %pI4:%hu, mark: %x\n",
	181	iph->protocol, &iph->saddr, ntohs(hp->source),
	182	&iph->daddr, ntohs(hp->dest), skb->mark);
6ad78893 BS	183	return NF_DROP;
	184	}
	185
	186	static unsigned int
	187	tproxy_tg4_v0(struct sk_buff skb, const struct xt_action_param par)
	188	{
	189	const struct xt_tproxy_target_info *tgi = par->targinfo;
	190
	191	return tproxy_tg4(skb, tgi->laddr, tgi->lport, tgi->mark_mask, tgi->mark_value);
	192	}
	193
	194	static unsigned int
	195	tproxy_tg4_v1(struct sk_buff skb, const struct xt_action_param par)
	196	{
	197	const struct xt_tproxy_target_info_v1 *tgi = par->targinfo;
	198
	199	return tproxy_tg4(skb, tgi->laddr.ip, tgi->lport, tgi->mark_mask, tgi->mark_value);
	200	}
	201
f6318e55	202	#ifdef XT_TPROXY_HAVE_IPV6
cc6eb433 BS	203
	204	static inline const struct in6_addr *
	205	tproxy_laddr6(struct sk_buff skb, const struct in6_addr user_laddr,
	206	const struct in6_addr *daddr)
	207	{
	208	struct inet6_dev *indev;
	209	struct inet6_ifaddr *ifa;
	210	struct in6_addr *laddr;
	211
	212	if (!ipv6_addr_any(user_laddr))
	213	return user_laddr;
	214	laddr = NULL;
	215
	216	rcu_read_lock();
	217	indev = __in6_dev_get(skb->dev);
	218	if (indev)
	219	list_for_each_entry(ifa, &indev->addr_list, if_list) {
	220	if (ifa->flags & (IFA_F_TENTATIVE \| IFA_F_DEPRECATED))
	221	continue;
	222
	223	laddr = &ifa->addr;
	224	break;
	225	}
	226	rcu_read_unlock();
	227
	228	return laddr ? laddr : daddr;
	229	}
	230
	231	/**
2c53040f	232	* tproxy_handle_time_wait6 - handle IPv6 TCP TIME_WAIT reopen redirections
cc6eb433 BS	233	* @skb: The skb being processed.
	234	* @tproto: Transport protocol.
	235	* @thoff: Transport protocol header offset.
	236	* @par: Iptables target parameters.
	237	* @sk: The TIME_WAIT TCP socket found by the lookup.
	238	*
	239	* We have to handle SYN packets arriving to TIME_WAIT sockets
	240	* differently: instead of reopening the connection we should rather
	241	* redirect the new connection to the proxy if there's a listener
	242	* socket present.
	243	*
	244	* tproxy_handle_time_wait6() consumes the socket reference passed in.
	245	*
	246	* Returns the listener socket if there's one, the TIME_WAIT socket if
	247	* no such listener is found, or NULL if the TCP header is incomplete.
	248	*/
	249	static struct sock *
	250	tproxy_handle_time_wait6(struct sk_buff *skb, int tproto, int thoff,
	251	const struct xt_action_param *par,
	252	struct sock *sk)
	253	{
	254	const struct ipv6hdr *iph = ipv6_hdr(skb);
	255	struct tcphdr _hdr, *hp;
	256	const struct xt_tproxy_target_info_v1 *tgi = par->targinfo;
	257
	258	hp = skb_header_pointer(skb, thoff, sizeof(_hdr), &_hdr);
	259	if (hp == NULL) {
	260	inet_twsk_put(inet_twsk(sk));
	261	return NULL;
	262	}
	263
	264	if (hp->syn && !hp->rst && !hp->ack && !hp->fin) {
	265	/* SYN to a TIME_WAIT socket, we'd rather redirect it
	266	* to a listener socket if there's one */
	267	struct sock *sk2;
	268
	269	sk2 = nf_tproxy_get_sock_v6(dev_net(skb->dev), tproto,
	270	&iph->saddr,
	271	tproxy_laddr6(skb, &tgi->laddr.in6, &iph->daddr),
	272	hp->source,
	273	tgi->lport ? tgi->lport : hp->dest,
	274	skb->dev, NFT_LOOKUP_LISTENER);
	275	if (sk2) {
	276	inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row);
	277	inet_twsk_put(inet_twsk(sk));
	278	sk = sk2;
	279	}
	280	}
	281
	282	return sk;
	283	}
	284
6ad78893 BS	285	static unsigned int
	286	tproxy_tg6_v1(struct sk_buff skb, const struct xt_action_param par)
	287	{
	288	const struct ipv6hdr *iph = ipv6_hdr(skb);
	289	const struct xt_tproxy_target_info_v1 *tgi = par->targinfo;
	290	struct udphdr _hdr, *hp;
	291	struct sock *sk;
cc6eb433 BS	292	const struct in6_addr *laddr;
cc6eb433 BS	293	__be16 lport;
84018f55	294	int thoff = 0;
6ad78893 BS	295	int tproto;
6ad78893 BS	296
84018f55	297	tproto = ipv6_find_hdr(skb, &thoff, -1, NULL, NULL);
6ad78893 BS	298	if (tproto < 0) {
	299	pr_debug("unable to find transport header in IPv6 packet, dropping\n");
	300	return NF_DROP;
	301	}
	302
	303	hp = skb_header_pointer(skb, thoff, sizeof(_hdr), &_hdr);
	304	if (hp == NULL) {
	305	pr_debug("unable to grab transport header contents in IPv6 packet, dropping\n");
	306	return NF_DROP;
	307	}
	308
	309	/* check if there's an ongoing connection on the packet
	310	* addresses, this happens if the redirect already happened
	311	* and the current packet belongs to an already established
	312	* connection */
	313	sk = nf_tproxy_get_sock_v6(dev_net(skb->dev), tproto,
	314	&iph->saddr, &iph->daddr,
	315	hp->source, hp->dest,
	316	par->in, NFT_LOOKUP_ESTABLISHED);
	317
cc6eb433 BS	318	laddr = tproxy_laddr6(skb, &tgi->laddr.in6, &iph->daddr);
	319	lport = tgi->lport ? tgi->lport : hp->dest;
	320
6ad78893 BS	321	/* UDP has no TCP_TIME_WAIT state, so we never enter here */
	322	if (sk && sk->sk_state == TCP_TIME_WAIT)
	323	/* reopening a TIME_WAIT connection needs special handling */
	324	sk = tproxy_handle_time_wait6(skb, tproto, thoff, par, sk);
	325	else if (!sk)
	326	/* no there's no established connection, check if
	327	* there's a listener on the redirected addr/port */
	328	sk = nf_tproxy_get_sock_v6(dev_net(skb->dev), tproto,
cc6eb433 BS	329	&iph->saddr, laddr,
cc6eb433 BS	330	hp->source, lport,
106e4c26	331	par->in, NFT_LOOKUP_LISTENER);
e8439270 KK	332
e8439270 KK	333	/* NOTE: assign_sock consumes our sk reference */
d503b30b	334	if (sk && tproxy_sk_is_transparent(sk)) {
e8439270 KK	335	/* This should be in a separate target, but we don't do multiple
	336	targets on the same rule yet */
	337	skb->mark = (skb->mark & ~tgi->mark_mask) ^ tgi->mark_value;
	338
6ad78893	339	pr_debug("redirecting: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
cc6eb433 BS	340	tproto, &iph->saddr, ntohs(hp->source),
cc6eb433 BS	341	laddr, ntohs(lport), skb->mark);
d503b30b FW	342
d503b30b FW	343	nf_tproxy_assign_sock(skb, sk);
e8439270 KK	344	return NF_ACCEPT;
	345	}
	346
6ad78893	347	pr_debug("no socket, dropping: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
cc6eb433 BS	348	tproto, &iph->saddr, ntohs(hp->source),
	349	&iph->daddr, ntohs(hp->dest), skb->mark);
	350
e8439270 KK	351	return NF_DROP;
	352	}
	353
6ad78893 BS	354	static int tproxy_tg6_check(const struct xt_tgchk_param *par)
	355	{
	356	const struct ip6t_ip6 *i = par->entryinfo;
	357
	358	if ((i->proto == IPPROTO_TCP \|\| i->proto == IPPROTO_UDP)
	359	&& !(i->flags & IP6T_INV_PROTO))
	360	return 0;
	361
	362	pr_info("Can be used only in combination with "
	363	"either -p tcp or -p udp\n");
	364	return -EINVAL;
	365	}
	366	#endif
	367
	368	static int tproxy_tg4_check(const struct xt_tgchk_param *par)
e8439270	369	{
af5d6dc2	370	const struct ipt_ip *i = par->entryinfo;
e8439270 KK	371
	372	if ((i->proto == IPPROTO_TCP \|\| i->proto == IPPROTO_UDP)
	373	&& !(i->invflags & IPT_INV_PROTO))
d6b00a53	374	return 0;
e8439270	375
ff67e4e4	376	pr_info("Can be used only in combination with "
e8439270	377	"either -p tcp or -p udp\n");
d6b00a53	378	return -EINVAL;
e8439270 KK	379	}
e8439270 KK	380
6ad78893 BS	381	static struct xt_target tproxy_tg_reg[] __read_mostly = {
	382	{
	383	.name = "TPROXY",
	384	.family = NFPROTO_IPV4,
	385	.table = "mangle",
	386	.target = tproxy_tg4_v0,
	387	.revision = 0,
	388	.targetsize = sizeof(struct xt_tproxy_target_info),
	389	.checkentry = tproxy_tg4_check,
	390	.hooks = 1 << NF_INET_PRE_ROUTING,
	391	.me = THIS_MODULE,
	392	},
	393	{
	394	.name = "TPROXY",
	395	.family = NFPROTO_IPV4,
	396	.table = "mangle",
	397	.target = tproxy_tg4_v1,
	398	.revision = 1,
	399	.targetsize = sizeof(struct xt_tproxy_target_info_v1),
	400	.checkentry = tproxy_tg4_check,
	401	.hooks = 1 << NF_INET_PRE_ROUTING,
	402	.me = THIS_MODULE,
	403	},
f6318e55	404	#ifdef XT_TPROXY_HAVE_IPV6
6ad78893 BS	405	{
	406	.name = "TPROXY",
	407	.family = NFPROTO_IPV6,
	408	.table = "mangle",
	409	.target = tproxy_tg6_v1,
	410	.revision = 1,
	411	.targetsize = sizeof(struct xt_tproxy_target_info_v1),
	412	.checkentry = tproxy_tg6_check,
	413	.hooks = 1 << NF_INET_PRE_ROUTING,
	414	.me = THIS_MODULE,
	415	},
	416	#endif
	417
e8439270 KK	418	};
	419
	420	static int __init tproxy_tg_init(void)
	421	{
	422	nf_defrag_ipv4_enable();
f6318e55	423	#ifdef XT_TPROXY_HAVE_IPV6
6ad78893 BS	424	nf_defrag_ipv6_enable();
	425	#endif
	426
	427	return xt_register_targets(tproxy_tg_reg, ARRAY_SIZE(tproxy_tg_reg));
e8439270 KK	428	}
	429
	430	static void __exit tproxy_tg_exit(void)
	431	{
6ad78893	432	xt_unregister_targets(tproxy_tg_reg, ARRAY_SIZE(tproxy_tg_reg));
e8439270 KK	433	}
	434
	435	module_init(tproxy_tg_init);
	436	module_exit(tproxy_tg_exit);
	437	MODULE_LICENSE("GPL");
6ad78893	438	MODULE_AUTHOR("Balazs Scheidler, Krisztian Kovacs");
e8439270 KK	439	MODULE_DESCRIPTION("Netfilter transparent proxy (TPROXY) target module.");
e8439270 KK	440	MODULE_ALIAS("ipt_TPROXY");
6ad78893	441	MODULE_ALIAS("ip6t_TPROXY");