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

/* (C) 1999-2001 Paul `Rusty' Russell
 * (C) 2002-2006 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.
 */

/* Everything about the rules for NAT. */
#include <linux/types.h>
#include <linux/ip.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <linux/module.h>
#include <linux/kmod.h>
#include <linux/skbuff.h>
#include <linux/proc_fs.h>
#include <net/checksum.h>
#include <net/route.h>
#include <linux/bitops.h>

#include <linux/netfilter_ipv4/ip_tables.h>
#include <net/netfilter/nf_nat.h>
#include <net/netfilter/nf_nat_core.h>
#include <net/netfilter/nf_nat_rule.h>

#define NAT_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \
			 (1 << NF_INET_POST_ROUTING) | \
			 (1 << NF_INET_LOCAL_OUT))

static struct
{
	struct ipt_replace repl;
	struct ipt_standard entries[3];
	struct ipt_error term;
} nat_initial_table __initdata = {
	.repl = {
		.name = "nat",
		.valid_hooks = NAT_VALID_HOOKS,
		.num_entries = 4,
		.size = sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error),
		.hook_entry = {
			[NF_INET_PRE_ROUTING] = 0,
			[NF_INET_POST_ROUTING] = sizeof(struct ipt_standard),
			[NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 2
		},
		.underflow = {
			[NF_INET_PRE_ROUTING] = 0,
			[NF_INET_POST_ROUTING] = sizeof(struct ipt_standard),
			[NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 2
		},
	},
	.entries = {
		IPT_STANDARD_INIT(NF_ACCEPT),	/* PRE_ROUTING */
		IPT_STANDARD_INIT(NF_ACCEPT),	/* POST_ROUTING */
		IPT_STANDARD_INIT(NF_ACCEPT),	/* LOCAL_OUT */
	},
	.term = IPT_ERROR_INIT,			/* ERROR */
};

static struct xt_table nat_table = {
	.name		= "nat",
	.valid_hooks	= NAT_VALID_HOOKS,
	.lock		= RW_LOCK_UNLOCKED,
	.me		= THIS_MODULE,
	.af		= AF_INET,
};

/* Source NAT */
static unsigned int ipt_snat_target(struct sk_buff *skb,
				    const struct net_device *in,
				    const struct net_device *out,
				    unsigned int hooknum,
				    const struct xt_target *target,
				    const void *targinfo)
{
	struct nf_conn *ct;
	enum ip_conntrack_info ctinfo;
	const struct nf_nat_multi_range_compat *mr = targinfo;

	NF_CT_ASSERT(hooknum == NF_INET_POST_ROUTING);

	ct = nf_ct_get(skb, &ctinfo);

	/* Connection must be valid and new. */
	NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
			    ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY));
	NF_CT_ASSERT(out);

	return nf_nat_setup_info(ct, &mr->range[0], hooknum);
}

/* Before 2.6.11 we did implicit source NAT if required. Warn about change. */
static void warn_if_extra_mangle(__be32 dstip, __be32 srcip)
{
	static int warned = 0;
	struct flowi fl = { .nl_u = { .ip4_u = { .daddr = dstip } } };
	struct rtable *rt;

	if (ip_route_output_key(&rt, &fl) != 0)
		return;

	if (rt->rt_src != srcip && !warned) {
		printk("NAT: no longer support implicit source local NAT\n");
		printk("NAT: packet src %u.%u.%u.%u -> dst %u.%u.%u.%u\n",
		       NIPQUAD(srcip), NIPQUAD(dstip));
		warned = 1;
	}
	ip_rt_put(rt);
}

static unsigned int ipt_dnat_target(struct sk_buff *skb,
				    const struct net_device *in,
				    const struct net_device *out,
				    unsigned int hooknum,
				    const struct xt_target *target,
				    const void *targinfo)
{
	struct nf_conn *ct;
	enum ip_conntrack_info ctinfo;
	const struct nf_nat_multi_range_compat *mr = targinfo;

	NF_CT_ASSERT(hooknum == NF_INET_PRE_ROUTING ||
		     hooknum == NF_INET_LOCAL_OUT);

	ct = nf_ct_get(skb, &ctinfo);

	/* Connection must be valid and new. */
	NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));

	if (hooknum == NF_INET_LOCAL_OUT &&
	    mr->range[0].flags & IP_NAT_RANGE_MAP_IPS)
		warn_if_extra_mangle(ip_hdr(skb)->daddr,
				     mr->range[0].min_ip);

	return nf_nat_setup_info(ct, &mr->range[0], hooknum);
}

static bool ipt_snat_checkentry(const char *tablename,
				const void *entry,
				const struct xt_target *target,
				void *targinfo,
				unsigned int hook_mask)
{
	struct nf_nat_multi_range_compat *mr = targinfo;

	/* Must be a valid range */
	if (mr->rangesize != 1) {
		printk("SNAT: multiple ranges no longer supported\n");
		return false;
	}
	return true;
}

static bool ipt_dnat_checkentry(const char *tablename,
				const void *entry,
				const struct xt_target *target,
				void *targinfo,
				unsigned int hook_mask)
{
	struct nf_nat_multi_range_compat *mr = targinfo;

	/* Must be a valid range */
	if (mr->rangesize != 1) {
		printk("DNAT: multiple ranges no longer supported\n");
		return false;
	}
	return true;
}

unsigned int
alloc_null_binding(struct nf_conn *ct, unsigned int hooknum)
{
	/* Force range to this IP; let proto decide mapping for
	   per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
	   Use reply in case it's already been mangled (eg local packet).
	*/
	__be32 ip
		= (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
		   ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip
		   : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip);
	struct nf_nat_range range
		= { IP_NAT_RANGE_MAP_IPS, ip, ip, { 0 }, { 0 } };

	pr_debug("Allocating NULL binding for %p (%u.%u.%u.%u)\n",
		 ct, NIPQUAD(ip));
	return nf_nat_setup_info(ct, &range, hooknum);
}

unsigned int
alloc_null_binding_confirmed(struct nf_conn *ct, unsigned int hooknum)
{
	__be32 ip
		= (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
		   ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip
		   : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip);
	__be16 all
		= (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
		   ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u.all
		   : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u.all);
	struct nf_nat_range range
		= { IP_NAT_RANGE_MAP_IPS, ip, ip, { all }, { all } };

	pr_debug("Allocating NULL binding for confirmed %p (%u.%u.%u.%u)\n",
		 ct, NIPQUAD(ip));
	return nf_nat_setup_info(ct, &range, hooknum);
}

int nf_nat_rule_find(struct sk_buff *skb,
		     unsigned int hooknum,
		     const struct net_device *in,
		     const struct net_device *out,
		     struct nf_conn *ct)
{
	int ret;

	ret = ipt_do_table(skb, hooknum, in, out, &nat_table);

	if (ret == NF_ACCEPT) {
		if (!nf_nat_initialized(ct, HOOK2MANIP(hooknum)))
			/* NUL mapping */
			ret = alloc_null_binding(ct, hooknum);
	}
	return ret;
}

static struct xt_target ipt_snat_reg __read_mostly = {
	.name		= "SNAT",
	.target		= ipt_snat_target,
	.targetsize	= sizeof(struct nf_nat_multi_range_compat),
	.table		= "nat",
	.hooks		= 1 << NF_INET_POST_ROUTING,
	.checkentry	= ipt_snat_checkentry,
	.family		= AF_INET,
};

static struct xt_target ipt_dnat_reg __read_mostly = {
	.name		= "DNAT",
	.target		= ipt_dnat_target,
	.targetsize	= sizeof(struct nf_nat_multi_range_compat),
	.table		= "nat",
	.hooks		= (1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_OUT),
	.checkentry	= ipt_dnat_checkentry,
	.family		= AF_INET,
};

int __init nf_nat_rule_init(void)
{
	int ret;

	ret = ipt_register_table(&nat_table, &nat_initial_table.repl);
	if (ret != 0)
		return ret;
	ret = xt_register_target(&ipt_snat_reg);
	if (ret != 0)
		goto unregister_table;

	ret = xt_register_target(&ipt_dnat_reg);
	if (ret != 0)
		goto unregister_snat;

	return ret;

 unregister_snat:
	xt_unregister_target(&ipt_snat_reg);
 unregister_table:
	ipt_unregister_table(&nat_table);

	return ret;
}

void nf_nat_rule_cleanup(void)
{
	xt_unregister_target(&ipt_dnat_reg);
	xt_unregister_target(&ipt_snat_reg);
	ipt_unregister_table(&nat_table);
}
Commit	Line	Data
5b1158e9 JK	1	/* (C) 1999-2001 Paul `Rusty' Russell
	2	* (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
	3	*
	4	* This program is free software; you can redistribute it and/or modify
	5	* it under the terms of the GNU General Public License version 2 as
	6	* published by the Free Software Foundation.
	7	*/
	8
	9	/* Everything about the rules for NAT. */
	10	#include <linux/types.h>
	11	#include <linux/ip.h>
	12	#include <linux/netfilter.h>
	13	#include <linux/netfilter_ipv4.h>
	14	#include <linux/module.h>
	15	#include <linux/kmod.h>
	16	#include <linux/skbuff.h>
	17	#include <linux/proc_fs.h>
	18	#include <net/checksum.h>
	19	#include <net/route.h>
	20	#include <linux/bitops.h>
	21
	22	#include <linux/netfilter_ipv4/ip_tables.h>
	23	#include <net/netfilter/nf_nat.h>
	24	#include <net/netfilter/nf_nat_core.h>
	25	#include <net/netfilter/nf_nat_rule.h>
	26
6e23ae2a PM	27	#define NAT_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) \| \
	28	(1 << NF_INET_POST_ROUTING) \| \
	29	(1 << NF_INET_LOCAL_OUT))
5b1158e9 JK	30
	31	static struct
	32	{
	33	struct ipt_replace repl;
	34	struct ipt_standard entries[3];
	35	struct ipt_error term;
	36	} nat_initial_table __initdata = {
	37	.repl = {
	38	.name = "nat",
	39	.valid_hooks = NAT_VALID_HOOKS,
	40	.num_entries = 4,
	41	.size = sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error),
	42	.hook_entry = {
6e23ae2a PM	43	[NF_INET_PRE_ROUTING] = 0,
	44	[NF_INET_POST_ROUTING] = sizeof(struct ipt_standard),
	45	[NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 2
3c2ad469	46	},
5b1158e9	47	.underflow = {
6e23ae2a PM	48	[NF_INET_PRE_ROUTING] = 0,
	49	[NF_INET_POST_ROUTING] = sizeof(struct ipt_standard),
	50	[NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 2
3c2ad469	51	},
5b1158e9 JK	52	},
5b1158e9 JK	53	.entries = {
3c2ad469 PM	54	IPT_STANDARD_INIT(NF_ACCEPT), /* PRE_ROUTING */
	55	IPT_STANDARD_INIT(NF_ACCEPT), /* POST_ROUTING */
	56	IPT_STANDARD_INIT(NF_ACCEPT), /* LOCAL_OUT */
5b1158e9	57	},
3c2ad469	58	.term = IPT_ERROR_INIT, /* ERROR */
5b1158e9 JK	59	};
5b1158e9 JK	60
e60a13e0	61	static struct xt_table nat_table = {
5b1158e9 JK	62	.name = "nat",
	63	.valid_hooks = NAT_VALID_HOOKS,
	64	.lock = RW_LOCK_UNLOCKED,
	65	.me = THIS_MODULE,
	66	.af = AF_INET,
	67	};
	68
	69	/* Source NAT */
3db05fea	70	static unsigned int ipt_snat_target(struct sk_buff *skb,
5b1158e9 JK	71	const struct net_device *in,
	72	const struct net_device *out,
	73	unsigned int hooknum,
	74	const struct xt_target *target,
	75	const void *targinfo)
	76	{
	77	struct nf_conn *ct;
	78	enum ip_conntrack_info ctinfo;
	79	const struct nf_nat_multi_range_compat *mr = targinfo;
	80
6e23ae2a	81	NF_CT_ASSERT(hooknum == NF_INET_POST_ROUTING);
5b1158e9	82
3db05fea	83	ct = nf_ct_get(skb, &ctinfo);
5b1158e9 JK	84
	85	/* Connection must be valid and new. */
	86	NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW \|\| ctinfo == IP_CT_RELATED \|\|
e905a9ed	87	ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY));
5b1158e9 JK	88	NF_CT_ASSERT(out);
	89
	90	return nf_nat_setup_info(ct, &mr->range[0], hooknum);
	91	}
	92
	93	/* Before 2.6.11 we did implicit source NAT if required. Warn about change. */
	94	static void warn_if_extra_mangle(__be32 dstip, __be32 srcip)
	95	{
	96	static int warned = 0;
	97	struct flowi fl = { .nl_u = { .ip4_u = { .daddr = dstip } } };
	98	struct rtable *rt;
	99
	100	if (ip_route_output_key(&rt, &fl) != 0)
	101	return;
	102
	103	if (rt->rt_src != srcip && !warned) {
	104	printk("NAT: no longer support implicit source local NAT\n");
	105	printk("NAT: packet src %u.%u.%u.%u -> dst %u.%u.%u.%u\n",
	106	NIPQUAD(srcip), NIPQUAD(dstip));
	107	warned = 1;
	108	}
	109	ip_rt_put(rt);
	110	}
	111
3db05fea	112	static unsigned int ipt_dnat_target(struct sk_buff *skb,
5b1158e9 JK	113	const struct net_device *in,
	114	const struct net_device *out,
	115	unsigned int hooknum,
	116	const struct xt_target *target,
	117	const void *targinfo)
	118	{
	119	struct nf_conn *ct;
	120	enum ip_conntrack_info ctinfo;
	121	const struct nf_nat_multi_range_compat *mr = targinfo;
	122
6e23ae2a PM	123	NF_CT_ASSERT(hooknum == NF_INET_PRE_ROUTING \|\|
6e23ae2a PM	124	hooknum == NF_INET_LOCAL_OUT);
5b1158e9	125
3db05fea	126	ct = nf_ct_get(skb, &ctinfo);
5b1158e9 JK	127
	128	/* Connection must be valid and new. */
	129	NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW \|\| ctinfo == IP_CT_RELATED));
	130
6e23ae2a	131	if (hooknum == NF_INET_LOCAL_OUT &&
5b1158e9	132	mr->range[0].flags & IP_NAT_RANGE_MAP_IPS)
3db05fea	133	warn_if_extra_mangle(ip_hdr(skb)->daddr,
5b1158e9 JK	134	mr->range[0].min_ip);
	135
	136	return nf_nat_setup_info(ct, &mr->range[0], hooknum);
	137	}
	138
e1931b78 JE	139	static bool ipt_snat_checkentry(const char *tablename,
	140	const void *entry,
	141	const struct xt_target *target,
	142	void *targinfo,
	143	unsigned int hook_mask)
5b1158e9 JK	144	{
	145	struct nf_nat_multi_range_compat *mr = targinfo;
	146
	147	/* Must be a valid range */
	148	if (mr->rangesize != 1) {
	149	printk("SNAT: multiple ranges no longer supported\n");
e1931b78	150	return false;
5b1158e9	151	}
e1931b78	152	return true;
5b1158e9 JK	153	}
5b1158e9 JK	154
e1931b78 JE	155	static bool ipt_dnat_checkentry(const char *tablename,
	156	const void *entry,
	157	const struct xt_target *target,
	158	void *targinfo,
	159	unsigned int hook_mask)
5b1158e9 JK	160	{
	161	struct nf_nat_multi_range_compat *mr = targinfo;
	162
	163	/* Must be a valid range */
	164	if (mr->rangesize != 1) {
	165	printk("DNAT: multiple ranges no longer supported\n");
e1931b78	166	return false;
5b1158e9	167	}
e1931b78	168	return true;
5b1158e9 JK	169	}
5b1158e9 JK	170
170b197c	171	unsigned int
ba4c7cba	172	alloc_null_binding(struct nf_conn *ct, unsigned int hooknum)
5b1158e9 JK	173	{
	174	/* Force range to this IP; let proto decide mapping for
	175	per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
	176	Use reply in case it's already been mangled (eg local packet).
	177	*/
	178	__be32 ip
	179	= (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
	180	? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip
	181	: ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip);
	182	struct nf_nat_range range
	183	= { IP_NAT_RANGE_MAP_IPS, ip, ip, { 0 }, { 0 } };
	184
0d53778e PM	185	pr_debug("Allocating NULL binding for %p (%u.%u.%u.%u)\n",
0d53778e PM	186	ct, NIPQUAD(ip));
5b1158e9 JK	187	return nf_nat_setup_info(ct, &range, hooknum);
	188	}
	189
	190	unsigned int
ba4c7cba	191	alloc_null_binding_confirmed(struct nf_conn *ct, unsigned int hooknum)
5b1158e9 JK	192	{
	193	__be32 ip
	194	= (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
	195	? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip
	196	: ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip);
a34c4589	197	__be16 all
5b1158e9 JK	198	= (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
	199	? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u.all
	200	: ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u.all);
	201	struct nf_nat_range range
	202	= { IP_NAT_RANGE_MAP_IPS, ip, ip, { all }, { all } };
	203
0d53778e PM	204	pr_debug("Allocating NULL binding for confirmed %p (%u.%u.%u.%u)\n",
0d53778e PM	205	ct, NIPQUAD(ip));
5b1158e9 JK	206	return nf_nat_setup_info(ct, &range, hooknum);
	207	}
	208
3db05fea	209	int nf_nat_rule_find(struct sk_buff *skb,
5b1158e9 JK	210	unsigned int hooknum,
	211	const struct net_device *in,
	212	const struct net_device *out,
ba4c7cba	213	struct nf_conn *ct)
5b1158e9 JK	214	{
	215	int ret;
	216
3db05fea	217	ret = ipt_do_table(skb, hooknum, in, out, &nat_table);
5b1158e9 JK	218
	219	if (ret == NF_ACCEPT) {
	220	if (!nf_nat_initialized(ct, HOOK2MANIP(hooknum)))
	221	/* NUL mapping */
ba4c7cba	222	ret = alloc_null_binding(ct, hooknum);
5b1158e9 JK	223	}
	224	return ret;
	225	}
	226
9f15c530	227	static struct xt_target ipt_snat_reg __read_mostly = {
5b1158e9 JK	228	.name = "SNAT",
	229	.target = ipt_snat_target,
	230	.targetsize = sizeof(struct nf_nat_multi_range_compat),
	231	.table = "nat",
6e23ae2a	232	.hooks = 1 << NF_INET_POST_ROUTING,
5b1158e9 JK	233	.checkentry = ipt_snat_checkentry,
	234	.family = AF_INET,
	235	};
	236
9f15c530	237	static struct xt_target ipt_dnat_reg __read_mostly = {
5b1158e9 JK	238	.name = "DNAT",
	239	.target = ipt_dnat_target,
	240	.targetsize = sizeof(struct nf_nat_multi_range_compat),
	241	.table = "nat",
6e23ae2a	242	.hooks = (1 << NF_INET_PRE_ROUTING) \| (1 << NF_INET_LOCAL_OUT),
5b1158e9 JK	243	.checkentry = ipt_dnat_checkentry,
	244	.family = AF_INET,
	245	};
	246
	247	int __init nf_nat_rule_init(void)
	248	{
	249	int ret;
	250
	251	ret = ipt_register_table(&nat_table, &nat_initial_table.repl);
	252	if (ret != 0)
	253	return ret;
	254	ret = xt_register_target(&ipt_snat_reg);
	255	if (ret != 0)
	256	goto unregister_table;
	257
	258	ret = xt_register_target(&ipt_dnat_reg);
	259	if (ret != 0)
	260	goto unregister_snat;
	261
	262	return ret;
	263
	264	unregister_snat:
	265	xt_unregister_target(&ipt_snat_reg);
	266	unregister_table:
	267	ipt_unregister_table(&nat_table);
	268
	269	return ret;
	270	}
	271
	272	void nf_nat_rule_cleanup(void)
	273	{
	274	xt_unregister_target(&ipt_dnat_reg);
	275	xt_unregister_target(&ipt_snat_reg);
	276	ipt_unregister_table(&nat_table);
	277	}