[deliverable/linux.git] / net / ipv4 / netfilter / ip_nat_standalone.c

/* This file contains all the functions required for the standalone
   ip_nat module.

   These are not required by the compatibility layer.
*/

/* (C) 1999-2001 Paul `Rusty' Russell
 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
 *
 * 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.
 */

/*
 * 23 Apr 2001: Harald Welte <laforge@gnumonks.org>
 * 	- new API and handling of conntrack/nat helpers
 * 	- now capable of multiple expectations for one master
 * */

#include <linux/config.h>
#include <linux/types.h>
#include <linux/icmp.h>
#include <linux/ip.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/proc_fs.h>
#include <net/ip.h>
#include <net/checksum.h>
#include <linux/spinlock.h>

#define ASSERT_READ_LOCK(x)
#define ASSERT_WRITE_LOCK(x)

#include <linux/netfilter_ipv4/ip_nat.h>
#include <linux/netfilter_ipv4/ip_nat_rule.h>
#include <linux/netfilter_ipv4/ip_nat_protocol.h>
#include <linux/netfilter_ipv4/ip_nat_core.h>
#include <linux/netfilter_ipv4/ip_nat_helper.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ip_conntrack_core.h>
#include <linux/netfilter_ipv4/listhelp.h>

#if 0
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif

#define HOOKNAME(hooknum) ((hooknum) == NF_IP_POST_ROUTING ? "POST_ROUTING"  \
			   : ((hooknum) == NF_IP_PRE_ROUTING ? "PRE_ROUTING" \
			      : ((hooknum) == NF_IP_LOCAL_OUT ? "LOCAL_OUT"  \
			         : ((hooknum) == NF_IP_LOCAL_IN ? "LOCAL_IN"  \
				    : "*ERROR*")))

#ifdef CONFIG_XFRM
static void nat_decode_session(struct sk_buff *skb, struct flowi *fl)
{
	struct ip_conntrack *ct;
	struct ip_conntrack_tuple *t;
	enum ip_conntrack_info ctinfo;
	enum ip_conntrack_dir dir;
	unsigned long statusbit;

	ct = ip_conntrack_get(skb, &ctinfo);
	if (ct == NULL)
		return;
	dir = CTINFO2DIR(ctinfo);
	t = &ct->tuplehash[dir].tuple;

	if (dir == IP_CT_DIR_ORIGINAL)
		statusbit = IPS_DST_NAT;
	else
		statusbit = IPS_SRC_NAT;

	if (ct->status & statusbit) {
		fl->fl4_dst = t->dst.ip;
		if (t->dst.protonum == IPPROTO_TCP ||
		    t->dst.protonum == IPPROTO_UDP)
			fl->fl_ip_dport = t->dst.u.tcp.port;
	}

	statusbit ^= IPS_NAT_MASK;

	if (ct->status & statusbit) {
		fl->fl4_src = t->src.ip;
		if (t->dst.protonum == IPPROTO_TCP ||
		    t->dst.protonum == IPPROTO_UDP)
			fl->fl_ip_sport = t->src.u.tcp.port;
	}
}
#endif
		
static unsigned int
ip_nat_fn(unsigned int hooknum,
	  struct sk_buff **pskb,
	  const struct net_device *in,
	  const struct net_device *out,
	  int (*okfn)(struct sk_buff *))
{
	struct ip_conntrack *ct;
	enum ip_conntrack_info ctinfo;
	struct ip_nat_info *info;
	/* maniptype == SRC for postrouting. */
	enum ip_nat_manip_type maniptype = HOOK2MANIP(hooknum);

	/* We never see fragments: conntrack defrags on pre-routing
	   and local-out, and ip_nat_out protects post-routing. */
	IP_NF_ASSERT(!((*pskb)->nh.iph->frag_off
		       & htons(IP_MF|IP_OFFSET)));

	/* If we had a hardware checksum before, it's now invalid */
	if ((*pskb)->ip_summed == CHECKSUM_HW)
		if (skb_checksum_help(*pskb, (out == NULL)))
			return NF_DROP;

	ct = ip_conntrack_get(*pskb, &ctinfo);
	/* Can't track?  It's not due to stress, or conntrack would
	   have dropped it.  Hence it's the user's responsibilty to
	   packet filter it out, or implement conntrack/NAT for that
	   protocol. 8) --RR */
	if (!ct) {
		/* Exception: ICMP redirect to new connection (not in
                   hash table yet).  We must not let this through, in
                   case we're doing NAT to the same network. */
		if ((*pskb)->nh.iph->protocol == IPPROTO_ICMP) {
			struct icmphdr _hdr, *hp;

			hp = skb_header_pointer(*pskb,
						(*pskb)->nh.iph->ihl*4,
						sizeof(_hdr), &_hdr);
			if (hp != NULL &&
			    hp->type == ICMP_REDIRECT)
				return NF_DROP;
		}
		return NF_ACCEPT;
	}

	/* Don't try to NAT if this packet is not conntracked */
	if (ct == &ip_conntrack_untracked)
		return NF_ACCEPT;

	switch (ctinfo) {
	case IP_CT_RELATED:
	case IP_CT_RELATED+IP_CT_IS_REPLY:
		if ((*pskb)->nh.iph->protocol == IPPROTO_ICMP) {
			if (!ip_nat_icmp_reply_translation(pskb, ct, maniptype,
							   CTINFO2DIR(ctinfo)))
				return NF_DROP;
			else
				return NF_ACCEPT;
		}
		/* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */
	case IP_CT_NEW:
		info = &ct->nat.info;

		/* Seen it before?  This can happen for loopback, retrans,
		   or local packets.. */
		if (!ip_nat_initialized(ct, maniptype)) {
			unsigned int ret;

			if (unlikely(is_confirmed(ct)))
				/* NAT module was loaded late */
				ret = alloc_null_binding_confirmed(ct, info,
				                                   hooknum);
			else if (hooknum == NF_IP_LOCAL_IN)
				/* LOCAL_IN hook doesn't have a chain!  */
				ret = alloc_null_binding(ct, info, hooknum);
			else
				ret = ip_nat_rule_find(pskb, hooknum,
						       in, out, ct,
						       info);

			if (ret != NF_ACCEPT) {
				return ret;
			}
		} else
			DEBUGP("Already setup manip %s for ct %p\n",
			       maniptype == IP_NAT_MANIP_SRC ? "SRC" : "DST",
			       ct);
		break;

	default:
		/* ESTABLISHED */
		IP_NF_ASSERT(ctinfo == IP_CT_ESTABLISHED
			     || ctinfo == (IP_CT_ESTABLISHED+IP_CT_IS_REPLY));
		info = &ct->nat.info;
	}

	IP_NF_ASSERT(info);
	return ip_nat_packet(ct, ctinfo, hooknum, pskb);
}

static unsigned int
ip_nat_in(unsigned int hooknum,
          struct sk_buff **pskb,
          const struct net_device *in,
          const struct net_device *out,
          int (*okfn)(struct sk_buff *))
{
	struct ip_conntrack *ct;
	enum ip_conntrack_info ctinfo;
	unsigned int ret;

	ret = ip_nat_fn(hooknum, pskb, in, out, okfn);
	if (ret != NF_DROP && ret != NF_STOLEN
	    && (ct = ip_conntrack_get(*pskb, &ctinfo)) != NULL) {
		enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);

		if (ct->tuplehash[dir].tuple.src.ip !=
		    ct->tuplehash[!dir].tuple.dst.ip) {
			dst_release((*pskb)->dst);
			(*pskb)->dst = NULL;
		}
	}
	return ret;
}

static unsigned int
ip_nat_out(unsigned int hooknum,
	   struct sk_buff **pskb,
	   const struct net_device *in,
	   const struct net_device *out,
	   int (*okfn)(struct sk_buff *))
{
	struct ip_conntrack *ct;
	enum ip_conntrack_info ctinfo;
	unsigned int ret;

	/* root is playing with raw sockets. */
	if ((*pskb)->len < sizeof(struct iphdr)
	    || (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr))
		return NF_ACCEPT;

	ret = ip_nat_fn(hooknum, pskb, in, out, okfn);
	if (ret != NF_DROP && ret != NF_STOLEN
	    && (ct = ip_conntrack_get(*pskb, &ctinfo)) != NULL) {
		enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);

		if (ct->tuplehash[dir].tuple.src.ip !=
		    ct->tuplehash[!dir].tuple.dst.ip
#ifdef CONFIG_XFRM
		    || ct->tuplehash[dir].tuple.src.u.all !=
		       ct->tuplehash[!dir].tuple.dst.u.all
#endif
		    )
			return ip_route_me_harder(pskb) == 0 ? ret : NF_DROP;
	}
	return ret;
}

static unsigned int
ip_nat_local_fn(unsigned int hooknum,
		struct sk_buff **pskb,
		const struct net_device *in,
		const struct net_device *out,
		int (*okfn)(struct sk_buff *))
{
	struct ip_conntrack *ct;
	enum ip_conntrack_info ctinfo;
	unsigned int ret;

	/* root is playing with raw sockets. */
	if ((*pskb)->len < sizeof(struct iphdr)
	    || (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr))
		return NF_ACCEPT;

	ret = ip_nat_fn(hooknum, pskb, in, out, okfn);
	if (ret != NF_DROP && ret != NF_STOLEN
	    && (ct = ip_conntrack_get(*pskb, &ctinfo)) != NULL) {
		enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);

		if (ct->tuplehash[dir].tuple.dst.ip !=
		    ct->tuplehash[!dir].tuple.src.ip
#ifdef CONFIG_XFRM
		    || ct->tuplehash[dir].tuple.dst.u.all !=
		       ct->tuplehash[dir].tuple.src.u.all
#endif
		    )
			return ip_route_me_harder(pskb) == 0 ? ret : NF_DROP;
	}
	return ret;
}

static unsigned int
ip_nat_adjust(unsigned int hooknum,
	      struct sk_buff **pskb,
	      const struct net_device *in,
	      const struct net_device *out,
	      int (*okfn)(struct sk_buff *))
{
	struct ip_conntrack *ct;
	enum ip_conntrack_info ctinfo;

	ct = ip_conntrack_get(*pskb, &ctinfo);
	if (ct && test_bit(IPS_SEQ_ADJUST_BIT, &ct->status)) {
	        DEBUGP("ip_nat_standalone: adjusting sequence number\n");
	        if (!ip_nat_seq_adjust(pskb, ct, ctinfo))
	                return NF_DROP;
	}
	return NF_ACCEPT;
}

/* We must be after connection tracking and before packet filtering. */

/* Before packet filtering, change destination */
static struct nf_hook_ops ip_nat_in_ops = {
	.hook		= ip_nat_in,
	.owner		= THIS_MODULE,
	.pf		= PF_INET,
	.hooknum	= NF_IP_PRE_ROUTING,
	.priority	= NF_IP_PRI_NAT_DST,
};

/* After packet filtering, change source */
static struct nf_hook_ops ip_nat_out_ops = {
	.hook		= ip_nat_out,
	.owner		= THIS_MODULE,
	.pf		= PF_INET,
	.hooknum	= NF_IP_POST_ROUTING,
	.priority	= NF_IP_PRI_NAT_SRC,
};

/* After conntrack, adjust sequence number */
static struct nf_hook_ops ip_nat_adjust_out_ops = {
	.hook		= ip_nat_adjust,
	.owner		= THIS_MODULE,
	.pf		= PF_INET,
	.hooknum	= NF_IP_POST_ROUTING,
	.priority	= NF_IP_PRI_NAT_SEQ_ADJUST,
};

/* Before packet filtering, change destination */
static struct nf_hook_ops ip_nat_local_out_ops = {
	.hook		= ip_nat_local_fn,
	.owner		= THIS_MODULE,
	.pf		= PF_INET,
	.hooknum	= NF_IP_LOCAL_OUT,
	.priority	= NF_IP_PRI_NAT_DST,
};

/* After packet filtering, change source for reply packets of LOCAL_OUT DNAT */
static struct nf_hook_ops ip_nat_local_in_ops = {
	.hook		= ip_nat_fn,
	.owner		= THIS_MODULE,
	.pf		= PF_INET,
	.hooknum	= NF_IP_LOCAL_IN,
	.priority	= NF_IP_PRI_NAT_SRC,
};

/* After conntrack, adjust sequence number */
static struct nf_hook_ops ip_nat_adjust_in_ops = {
	.hook		= ip_nat_adjust,
	.owner		= THIS_MODULE,
	.pf		= PF_INET,
	.hooknum	= NF_IP_LOCAL_IN,
	.priority	= NF_IP_PRI_NAT_SEQ_ADJUST,
};


static int init_or_cleanup(int init)
{
	int ret = 0;

	need_ip_conntrack();

	if (!init) goto cleanup;

#ifdef CONFIG_XFRM
	BUG_ON(ip_nat_decode_session != NULL);
	ip_nat_decode_session = nat_decode_session;
#endif
	ret = ip_nat_rule_init();
	if (ret < 0) {
		printk("ip_nat_init: can't setup rules.\n");
		goto cleanup_decode_session;
	}
	ret = nf_register_hook(&ip_nat_in_ops);
	if (ret < 0) {
		printk("ip_nat_init: can't register in hook.\n");
		goto cleanup_rule_init;
	}
	ret = nf_register_hook(&ip_nat_out_ops);
	if (ret < 0) {
		printk("ip_nat_init: can't register out hook.\n");
		goto cleanup_inops;
	}
	ret = nf_register_hook(&ip_nat_adjust_in_ops);
	if (ret < 0) {
		printk("ip_nat_init: can't register adjust in hook.\n");
		goto cleanup_outops;
	}
	ret = nf_register_hook(&ip_nat_adjust_out_ops);
	if (ret < 0) {
		printk("ip_nat_init: can't register adjust out hook.\n");
		goto cleanup_adjustin_ops;
	}
	ret = nf_register_hook(&ip_nat_local_out_ops);
	if (ret < 0) {
		printk("ip_nat_init: can't register local out hook.\n");
		goto cleanup_adjustout_ops;;
	}
	ret = nf_register_hook(&ip_nat_local_in_ops);
	if (ret < 0) {
		printk("ip_nat_init: can't register local in hook.\n");
		goto cleanup_localoutops;
	}
	return ret;

 cleanup:
	nf_unregister_hook(&ip_nat_local_in_ops);
 cleanup_localoutops:
	nf_unregister_hook(&ip_nat_local_out_ops);
 cleanup_adjustout_ops:
	nf_unregister_hook(&ip_nat_adjust_out_ops);
 cleanup_adjustin_ops:
	nf_unregister_hook(&ip_nat_adjust_in_ops);
 cleanup_outops:
	nf_unregister_hook(&ip_nat_out_ops);
 cleanup_inops:
	nf_unregister_hook(&ip_nat_in_ops);
 cleanup_rule_init:
	ip_nat_rule_cleanup();
 cleanup_decode_session:
#ifdef CONFIG_XFRM
	ip_nat_decode_session = NULL;
	synchronize_net();
#endif
	return ret;
}

static int __init init(void)
{
	return init_or_cleanup(1);
}

static void __exit fini(void)
{
	init_or_cleanup(0);
}

module_init(init);
module_exit(fini);

MODULE_LICENSE("GPL");
Commit	Line	Data
1da177e4 LT	1	/* This file contains all the functions required for the standalone
	2	ip_nat module.
	3
	4	These are not required by the compatibility layer.
	5	*/
	6
	7	/* (C) 1999-2001 Paul `Rusty' Russell
	8	* (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
	9	*
	10	* This program is free software; you can redistribute it and/or modify
	11	* it under the terms of the GNU General Public License version 2 as
	12	* published by the Free Software Foundation.
	13	*/
	14
	15	/*
	16	* 23 Apr 2001: Harald Welte <laforge@gnumonks.org>
	17	* - new API and handling of conntrack/nat helpers
	18	* - now capable of multiple expectations for one master
	19	* */
	20
	21	#include <linux/config.h>
	22	#include <linux/types.h>
	23	#include <linux/icmp.h>
	24	#include <linux/ip.h>
	25	#include <linux/netfilter.h>
	26	#include <linux/netfilter_ipv4.h>
	27	#include <linux/module.h>
	28	#include <linux/skbuff.h>
	29	#include <linux/proc_fs.h>
	30	#include <net/ip.h>
	31	#include <net/checksum.h>
	32	#include <linux/spinlock.h>
	33
e45b1be8 PM	34	#define ASSERT_READ_LOCK(x)
e45b1be8 PM	35	#define ASSERT_WRITE_LOCK(x)
1da177e4 LT	36
	37	#include <linux/netfilter_ipv4/ip_nat.h>
	38	#include <linux/netfilter_ipv4/ip_nat_rule.h>
	39	#include <linux/netfilter_ipv4/ip_nat_protocol.h>
	40	#include <linux/netfilter_ipv4/ip_nat_core.h>
	41	#include <linux/netfilter_ipv4/ip_nat_helper.h>
	42	#include <linux/netfilter_ipv4/ip_tables.h>
	43	#include <linux/netfilter_ipv4/ip_conntrack_core.h>
	44	#include <linux/netfilter_ipv4/listhelp.h>
	45
	46	#if 0
	47	#define DEBUGP printk
	48	#else
	49	#define DEBUGP(format, args...)
	50	#endif
	51
	52	#define HOOKNAME(hooknum) ((hooknum) == NF_IP_POST_ROUTING ? "POST_ROUTING" \
	53	: ((hooknum) == NF_IP_PRE_ROUTING ? "PRE_ROUTING" \
	54	: ((hooknum) == NF_IP_LOCAL_OUT ? "LOCAL_OUT" \
	55	: ((hooknum) == NF_IP_LOCAL_IN ? "LOCAL_IN" \
	56	: "ERROR")))
	57
eb9c7ebe PM	58	#ifdef CONFIG_XFRM
	59	static void nat_decode_session(struct sk_buff skb, struct flowi fl)
	60	{
	61	struct ip_conntrack *ct;
	62	struct ip_conntrack_tuple *t;
	63	enum ip_conntrack_info ctinfo;
	64	enum ip_conntrack_dir dir;
	65	unsigned long statusbit;
	66
	67	ct = ip_conntrack_get(skb, &ctinfo);
	68	if (ct == NULL)
	69	return;
	70	dir = CTINFO2DIR(ctinfo);
	71	t = &ct->tuplehash[dir].tuple;
	72
	73	if (dir == IP_CT_DIR_ORIGINAL)
	74	statusbit = IPS_DST_NAT;
	75	else
	76	statusbit = IPS_SRC_NAT;
	77
	78	if (ct->status & statusbit) {
	79	fl->fl4_dst = t->dst.ip;
	80	if (t->dst.protonum == IPPROTO_TCP \|\|
	81	t->dst.protonum == IPPROTO_UDP)
	82	fl->fl_ip_dport = t->dst.u.tcp.port;
	83	}
	84
	85	statusbit ^= IPS_NAT_MASK;
	86
	87	if (ct->status & statusbit) {
	88	fl->fl4_src = t->src.ip;
	89	if (t->dst.protonum == IPPROTO_TCP \|\|
	90	t->dst.protonum == IPPROTO_UDP)
	91	fl->fl_ip_sport = t->src.u.tcp.port;
	92	}
	93	}
	94	#endif
	95
1da177e4 LT	96	static unsigned int
	97	ip_nat_fn(unsigned int hooknum,
	98	struct sk_buff **pskb,
	99	const struct net_device *in,
	100	const struct net_device *out,
	101	int (okfn)(struct sk_buff ))
	102	{
	103	struct ip_conntrack *ct;
	104	enum ip_conntrack_info ctinfo;
	105	struct ip_nat_info *info;
	106	/* maniptype == SRC for postrouting. */
	107	enum ip_nat_manip_type maniptype = HOOK2MANIP(hooknum);
	108
	109	/* We never see fragments: conntrack defrags on pre-routing
	110	and local-out, and ip_nat_out protects post-routing. */
	111	IP_NF_ASSERT(!((*pskb)->nh.iph->frag_off
	112	& htons(IP_MF\|IP_OFFSET)));
	113
1da177e4 LT	114	/* If we had a hardware checksum before, it's now invalid */
	115	if ((*pskb)->ip_summed == CHECKSUM_HW)
	116	if (skb_checksum_help(*pskb, (out == NULL)))
	117	return NF_DROP;
	118
	119	ct = ip_conntrack_get(*pskb, &ctinfo);
	120	/* Can't track? It's not due to stress, or conntrack would
	121	have dropped it. Hence it's the user's responsibilty to
	122	packet filter it out, or implement conntrack/NAT for that
	123	protocol. 8) --RR */
	124	if (!ct) {
	125	/* Exception: ICMP redirect to new connection (not in
	126	hash table yet). We must not let this through, in
	127	case we're doing NAT to the same network. */
	128	if ((*pskb)->nh.iph->protocol == IPPROTO_ICMP) {
	129	struct icmphdr _hdr, *hp;
	130
	131	hp = skb_header_pointer(*pskb,
	132	(pskb)->nh.iph->ihl4,
	133	sizeof(_hdr), &_hdr);
	134	if (hp != NULL &&
	135	hp->type == ICMP_REDIRECT)
	136	return NF_DROP;
	137	}
	138	return NF_ACCEPT;
	139	}
	140
8b83bc77 HW	141	/* Don't try to NAT if this packet is not conntracked */
	142	if (ct == &ip_conntrack_untracked)
	143	return NF_ACCEPT;
	144
1da177e4 LT	145	switch (ctinfo) {
	146	case IP_CT_RELATED:
	147	case IP_CT_RELATED+IP_CT_IS_REPLY:
	148	if ((*pskb)->nh.iph->protocol == IPPROTO_ICMP) {
188bab3a HW	149	if (!ip_nat_icmp_reply_translation(pskb, ct, maniptype,
188bab3a HW	150	CTINFO2DIR(ctinfo)))
1da177e4 LT	151	return NF_DROP;
	152	else
	153	return NF_ACCEPT;
	154	}
	155	/* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */
	156	case IP_CT_NEW:
	157	info = &ct->nat.info;
	158
	159	/* Seen it before? This can happen for loopback, retrans,
	160	or local packets.. */
	161	if (!ip_nat_initialized(ct, maniptype)) {
	162	unsigned int ret;
	163
03486a4f PM	164	if (unlikely(is_confirmed(ct)))
	165	/* NAT module was loaded late */
	166	ret = alloc_null_binding_confirmed(ct, info,
	167	hooknum);
	168	else if (hooknum == NF_IP_LOCAL_IN)
	169	/* LOCAL_IN hook doesn't have a chain! */
1da177e4 LT	170	ret = alloc_null_binding(ct, info, hooknum);
	171	else
	172	ret = ip_nat_rule_find(pskb, hooknum,
	173	in, out, ct,
	174	info);
	175
	176	if (ret != NF_ACCEPT) {
	177	return ret;
	178	}
	179	} else
	180	DEBUGP("Already setup manip %s for ct %p\n",
	181	maniptype == IP_NAT_MANIP_SRC ? "SRC" : "DST",
	182	ct);
	183	break;
	184
	185	default:
	186	/* ESTABLISHED */
	187	IP_NF_ASSERT(ctinfo == IP_CT_ESTABLISHED
	188	\|\| ctinfo == (IP_CT_ESTABLISHED+IP_CT_IS_REPLY));
	189	info = &ct->nat.info;
	190	}
	191
	192	IP_NF_ASSERT(info);
188bab3a	193	return ip_nat_packet(ct, ctinfo, hooknum, pskb);
1da177e4 LT	194	}
	195
	196	static unsigned int
	197	ip_nat_in(unsigned int hooknum,
	198	struct sk_buff **pskb,
	199	const struct net_device *in,
	200	const struct net_device *out,
	201	int (okfn)(struct sk_buff ))
	202	{
4e8e9de7 PM	203	struct ip_conntrack *ct;
4e8e9de7 PM	204	enum ip_conntrack_info ctinfo;
1da177e4 LT	205	unsigned int ret;
1da177e4 LT	206
1da177e4 LT	207	ret = ip_nat_fn(hooknum, pskb, in, out, okfn);
1da177e4 LT	208	if (ret != NF_DROP && ret != NF_STOLEN
4e8e9de7 PM	209	&& (ct = ip_conntrack_get(*pskb, &ctinfo)) != NULL) {
	210	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	211
	212	if (ct->tuplehash[dir].tuple.src.ip !=
	213	ct->tuplehash[!dir].tuple.dst.ip) {
	214	dst_release((*pskb)->dst);
	215	(*pskb)->dst = NULL;
	216	}
1da177e4 LT	217	}
	218	return ret;
	219	}
	220
	221	static unsigned int
	222	ip_nat_out(unsigned int hooknum,
	223	struct sk_buff **pskb,
	224	const struct net_device *in,
	225	const struct net_device *out,
	226	int (okfn)(struct sk_buff ))
	227	{
5c901daa PM	228	struct ip_conntrack *ct;
	229	enum ip_conntrack_info ctinfo;
	230	unsigned int ret;
	231
1da177e4 LT	232	/* root is playing with raw sockets. */
	233	if ((*pskb)->len < sizeof(struct iphdr)
	234	\|\| (pskb)->nh.iph->ihl 4 < sizeof(struct iphdr))
	235	return NF_ACCEPT;
	236
5c901daa PM	237	ret = ip_nat_fn(hooknum, pskb, in, out, okfn);
	238	if (ret != NF_DROP && ret != NF_STOLEN
	239	&& (ct = ip_conntrack_get(*pskb, &ctinfo)) != NULL) {
	240	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	241
	242	if (ct->tuplehash[dir].tuple.src.ip !=
	243	ct->tuplehash[!dir].tuple.dst.ip
	244	#ifdef CONFIG_XFRM
	245	\|\| ct->tuplehash[dir].tuple.src.u.all !=
	246	ct->tuplehash[!dir].tuple.dst.u.all
	247	#endif
	248	)
	249	return ip_route_me_harder(pskb) == 0 ? ret : NF_DROP;
	250	}
	251	return ret;
1da177e4 LT	252	}
	253
	254	static unsigned int
	255	ip_nat_local_fn(unsigned int hooknum,
	256	struct sk_buff **pskb,
	257	const struct net_device *in,
	258	const struct net_device *out,
	259	int (okfn)(struct sk_buff ))
	260	{
4e8e9de7 PM	261	struct ip_conntrack *ct;
4e8e9de7 PM	262	enum ip_conntrack_info ctinfo;
1da177e4 LT	263	unsigned int ret;
	264
	265	/* root is playing with raw sockets. */
	266	if ((*pskb)->len < sizeof(struct iphdr)
	267	\|\| (pskb)->nh.iph->ihl 4 < sizeof(struct iphdr))
	268	return NF_ACCEPT;
	269
1da177e4 LT	270	ret = ip_nat_fn(hooknum, pskb, in, out, okfn);
1da177e4 LT	271	if (ret != NF_DROP && ret != NF_STOLEN
4e8e9de7 PM	272	&& (ct = ip_conntrack_get(*pskb, &ctinfo)) != NULL) {
	273	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	274
	275	if (ct->tuplehash[dir].tuple.dst.ip !=
5c901daa PM	276	ct->tuplehash[!dir].tuple.src.ip
	277	#ifdef CONFIG_XFRM
	278	\|\| ct->tuplehash[dir].tuple.dst.u.all !=
	279	ct->tuplehash[dir].tuple.src.u.all
	280	#endif
	281	)
4e8e9de7 PM	282	return ip_route_me_harder(pskb) == 0 ? ret : NF_DROP;
4e8e9de7 PM	283	}
1da177e4 LT	284	return ret;
	285	}
	286
e281e3ac PM	287	static unsigned int
	288	ip_nat_adjust(unsigned int hooknum,
	289	struct sk_buff **pskb,
	290	const struct net_device *in,
	291	const struct net_device *out,
	292	int (okfn)(struct sk_buff ))
	293	{
	294	struct ip_conntrack *ct;
	295	enum ip_conntrack_info ctinfo;
	296
	297	ct = ip_conntrack_get(*pskb, &ctinfo);
	298	if (ct && test_bit(IPS_SEQ_ADJUST_BIT, &ct->status)) {
	299	DEBUGP("ip_nat_standalone: adjusting sequence number\n");
	300	if (!ip_nat_seq_adjust(pskb, ct, ctinfo))
	301	return NF_DROP;
	302	}
	303	return NF_ACCEPT;
	304	}
	305
1da177e4 LT	306	/* We must be after connection tracking and before packet filtering. */
	307
	308	/* Before packet filtering, change destination */
	309	static struct nf_hook_ops ip_nat_in_ops = {
	310	.hook = ip_nat_in,
	311	.owner = THIS_MODULE,
	312	.pf = PF_INET,
	313	.hooknum = NF_IP_PRE_ROUTING,
	314	.priority = NF_IP_PRI_NAT_DST,
	315	};
	316
	317	/* After packet filtering, change source */
	318	static struct nf_hook_ops ip_nat_out_ops = {
	319	.hook = ip_nat_out,
	320	.owner = THIS_MODULE,
	321	.pf = PF_INET,
	322	.hooknum = NF_IP_POST_ROUTING,
	323	.priority = NF_IP_PRI_NAT_SRC,
	324	};
	325
e281e3ac PM	326	/* After conntrack, adjust sequence number */
	327	static struct nf_hook_ops ip_nat_adjust_out_ops = {
	328	.hook = ip_nat_adjust,
	329	.owner = THIS_MODULE,
	330	.pf = PF_INET,
	331	.hooknum = NF_IP_POST_ROUTING,
	332	.priority = NF_IP_PRI_NAT_SEQ_ADJUST,
	333	};
	334
1da177e4 LT	335	/* Before packet filtering, change destination */
	336	static struct nf_hook_ops ip_nat_local_out_ops = {
	337	.hook = ip_nat_local_fn,
	338	.owner = THIS_MODULE,
	339	.pf = PF_INET,
	340	.hooknum = NF_IP_LOCAL_OUT,
	341	.priority = NF_IP_PRI_NAT_DST,
	342	};
	343
	344	/* After packet filtering, change source for reply packets of LOCAL_OUT DNAT */
	345	static struct nf_hook_ops ip_nat_local_in_ops = {
	346	.hook = ip_nat_fn,
	347	.owner = THIS_MODULE,
	348	.pf = PF_INET,
	349	.hooknum = NF_IP_LOCAL_IN,
	350	.priority = NF_IP_PRI_NAT_SRC,
	351	};
	352
e281e3ac PM	353	/* After conntrack, adjust sequence number */
	354	static struct nf_hook_ops ip_nat_adjust_in_ops = {
	355	.hook = ip_nat_adjust,
	356	.owner = THIS_MODULE,
	357	.pf = PF_INET,
	358	.hooknum = NF_IP_LOCAL_IN,
	359	.priority = NF_IP_PRI_NAT_SEQ_ADJUST,
	360	};
	361
	362
1da177e4 LT	363	static int init_or_cleanup(int init)
	364	{
	365	int ret = 0;
	366
	367	need_ip_conntrack();
	368
	369	if (!init) goto cleanup;
	370
eb9c7ebe PM	371	#ifdef CONFIG_XFRM
	372	BUG_ON(ip_nat_decode_session != NULL);
	373	ip_nat_decode_session = nat_decode_session;
	374	#endif
1da177e4 LT	375	ret = ip_nat_rule_init();
	376	if (ret < 0) {
	377	printk("ip_nat_init: can't setup rules.\n");
eb9c7ebe	378	goto cleanup_decode_session;
1da177e4	379	}
1da177e4 LT	380	ret = nf_register_hook(&ip_nat_in_ops);
	381	if (ret < 0) {
	382	printk("ip_nat_init: can't register in hook.\n");
188bab3a	383	goto cleanup_rule_init;
1da177e4 LT	384	}
	385	ret = nf_register_hook(&ip_nat_out_ops);
	386	if (ret < 0) {
	387	printk("ip_nat_init: can't register out hook.\n");
	388	goto cleanup_inops;
	389	}
e281e3ac PM	390	ret = nf_register_hook(&ip_nat_adjust_in_ops);
	391	if (ret < 0) {
	392	printk("ip_nat_init: can't register adjust in hook.\n");
	393	goto cleanup_outops;
	394	}
	395	ret = nf_register_hook(&ip_nat_adjust_out_ops);
	396	if (ret < 0) {
	397	printk("ip_nat_init: can't register adjust out hook.\n");
	398	goto cleanup_adjustin_ops;
	399	}
1da177e4 LT	400	ret = nf_register_hook(&ip_nat_local_out_ops);
	401	if (ret < 0) {
	402	printk("ip_nat_init: can't register local out hook.\n");
e281e3ac	403	goto cleanup_adjustout_ops;;
1da177e4 LT	404	}
	405	ret = nf_register_hook(&ip_nat_local_in_ops);
	406	if (ret < 0) {
	407	printk("ip_nat_init: can't register local in hook.\n");
	408	goto cleanup_localoutops;
	409	}
	410	return ret;
	411
	412	cleanup:
	413	nf_unregister_hook(&ip_nat_local_in_ops);
	414	cleanup_localoutops:
	415	nf_unregister_hook(&ip_nat_local_out_ops);
e281e3ac PM	416	cleanup_adjustout_ops:
	417	nf_unregister_hook(&ip_nat_adjust_out_ops);
	418	cleanup_adjustin_ops:
	419	nf_unregister_hook(&ip_nat_adjust_in_ops);
1da177e4 LT	420	cleanup_outops:
	421	nf_unregister_hook(&ip_nat_out_ops);
	422	cleanup_inops:
	423	nf_unregister_hook(&ip_nat_in_ops);
1da177e4 LT	424	cleanup_rule_init:
1da177e4 LT	425	ip_nat_rule_cleanup();
eb9c7ebe PM	426	cleanup_decode_session:
	427	#ifdef CONFIG_XFRM
	428	ip_nat_decode_session = NULL;
	429	synchronize_net();
	430	#endif
1da177e4 LT	431	return ret;
	432	}
	433
	434	static int __init init(void)
	435	{
	436	return init_or_cleanup(1);
	437	}
	438
	439	static void __exit fini(void)
	440	{
	441	init_or_cleanup(0);
	442	}
	443
	444	module_init(init);
	445	module_exit(fini);
	446
1da177e4	447	MODULE_LICENSE("GPL");