[net-next-2.6.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_IP_PRE_ROUTING) | (1<<NF_IP_POST_ROUTING) | (1<<NF_IP_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_IP_PRE_ROUTING] = 0,
			[NF_IP_POST_ROUTING] = sizeof(struct ipt_standard),
			[NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2
		},
		.underflow = {
			[NF_IP_PRE_ROUTING] = 0,
			[NF_IP_POST_ROUTING] = sizeof(struct ipt_standard),
			[NF_IP_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 **pskb,
				    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_IP_POST_ROUTING);

	ct = nf_ct_get(*pskb, &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 **pskb,
				    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_IP_PRE_ROUTING ||
		     hooknum == NF_IP_LOCAL_OUT);

	ct = nf_ct_get(*pskb, &ctinfo);

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

	if (hooknum == NF_IP_LOCAL_OUT &&
	    mr->range[0].flags & IP_NAT_RANGE_MAP_IPS)
		warn_if_extra_mangle(ip_hdr(*pskb)->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 **pskb,
		     unsigned int hooknum,
		     const struct net_device *in,
		     const struct net_device *out,
		     struct nf_conn *ct)
{
	int ret;

	ret = ipt_do_table(pskb, 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_IP_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_IP_PRE_ROUTING) | (1 << NF_IP_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
5b1158e9 JK	27	#define NAT_VALID_HOOKS ((1<<NF_IP_PRE_ROUTING) \| (1<<NF_IP_POST_ROUTING) \| (1<<NF_IP_LOCAL_OUT))
	28
	29	static struct
	30	{
	31	struct ipt_replace repl;
	32	struct ipt_standard entries[3];
	33	struct ipt_error term;
	34	} nat_initial_table __initdata = {
	35	.repl = {
	36	.name = "nat",
	37	.valid_hooks = NAT_VALID_HOOKS,
	38	.num_entries = 4,
	39	.size = sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error),
	40	.hook_entry = {
	41	[NF_IP_PRE_ROUTING] = 0,
	42	[NF_IP_POST_ROUTING] = sizeof(struct ipt_standard),
3c2ad469 PM	43	[NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2
3c2ad469 PM	44	},
5b1158e9 JK	45	.underflow = {
	46	[NF_IP_PRE_ROUTING] = 0,
	47	[NF_IP_POST_ROUTING] = sizeof(struct ipt_standard),
3c2ad469 PM	48	[NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2
3c2ad469 PM	49	},
5b1158e9 JK	50	},
5b1158e9 JK	51	.entries = {
3c2ad469 PM	52	IPT_STANDARD_INIT(NF_ACCEPT), /* PRE_ROUTING */
	53	IPT_STANDARD_INIT(NF_ACCEPT), /* POST_ROUTING */
	54	IPT_STANDARD_INIT(NF_ACCEPT), /* LOCAL_OUT */
5b1158e9	55	},
3c2ad469	56	.term = IPT_ERROR_INIT, /* ERROR */
5b1158e9 JK	57	};
5b1158e9 JK	58
e60a13e0	59	static struct xt_table nat_table = {
5b1158e9 JK	60	.name = "nat",
	61	.valid_hooks = NAT_VALID_HOOKS,
	62	.lock = RW_LOCK_UNLOCKED,
	63	.me = THIS_MODULE,
	64	.af = AF_INET,
	65	};
	66
	67	/* Source NAT */
	68	static unsigned int ipt_snat_target(struct sk_buff **pskb,
	69	const struct net_device *in,
	70	const struct net_device *out,
	71	unsigned int hooknum,
	72	const struct xt_target *target,
	73	const void *targinfo)
	74	{
	75	struct nf_conn *ct;
	76	enum ip_conntrack_info ctinfo;
	77	const struct nf_nat_multi_range_compat *mr = targinfo;
	78
	79	NF_CT_ASSERT(hooknum == NF_IP_POST_ROUTING);
	80
	81	ct = nf_ct_get(*pskb, &ctinfo);
	82
	83	/* Connection must be valid and new. */
	84	NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW \|\| ctinfo == IP_CT_RELATED \|\|
e905a9ed	85	ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY));
5b1158e9 JK	86	NF_CT_ASSERT(out);
	87
	88	return nf_nat_setup_info(ct, &mr->range[0], hooknum);
	89	}
	90
	91	/* Before 2.6.11 we did implicit source NAT if required. Warn about change. */
	92	static void warn_if_extra_mangle(__be32 dstip, __be32 srcip)
	93	{
	94	static int warned = 0;
	95	struct flowi fl = { .nl_u = { .ip4_u = { .daddr = dstip } } };
	96	struct rtable *rt;
	97
	98	if (ip_route_output_key(&rt, &fl) != 0)
	99	return;
	100
	101	if (rt->rt_src != srcip && !warned) {
	102	printk("NAT: no longer support implicit source local NAT\n");
	103	printk("NAT: packet src %u.%u.%u.%u -> dst %u.%u.%u.%u\n",
	104	NIPQUAD(srcip), NIPQUAD(dstip));
	105	warned = 1;
	106	}
	107	ip_rt_put(rt);
	108	}
	109
	110	static unsigned int ipt_dnat_target(struct sk_buff **pskb,
	111	const struct net_device *in,
	112	const struct net_device *out,
	113	unsigned int hooknum,
	114	const struct xt_target *target,
	115	const void *targinfo)
	116	{
	117	struct nf_conn *ct;
	118	enum ip_conntrack_info ctinfo;
	119	const struct nf_nat_multi_range_compat *mr = targinfo;
	120
	121	NF_CT_ASSERT(hooknum == NF_IP_PRE_ROUTING \|\|
	122	hooknum == NF_IP_LOCAL_OUT);
	123
	124	ct = nf_ct_get(*pskb, &ctinfo);
	125
	126	/* Connection must be valid and new. */
	127	NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW \|\| ctinfo == IP_CT_RELATED));
	128
	129	if (hooknum == NF_IP_LOCAL_OUT &&
	130	mr->range[0].flags & IP_NAT_RANGE_MAP_IPS)
eddc9ec5	131	warn_if_extra_mangle(ip_hdr(*pskb)->daddr,
5b1158e9 JK	132	mr->range[0].min_ip);
	133
	134	return nf_nat_setup_info(ct, &mr->range[0], hooknum);
	135	}
	136
e1931b78 JE	137	static bool ipt_snat_checkentry(const char *tablename,
	138	const void *entry,
	139	const struct xt_target *target,
	140	void *targinfo,
	141	unsigned int hook_mask)
5b1158e9 JK	142	{
	143	struct nf_nat_multi_range_compat *mr = targinfo;
	144
	145	/* Must be a valid range */
	146	if (mr->rangesize != 1) {
	147	printk("SNAT: multiple ranges no longer supported\n");
e1931b78	148	return false;
5b1158e9	149	}
e1931b78	150	return true;
5b1158e9 JK	151	}
5b1158e9 JK	152
e1931b78 JE	153	static bool ipt_dnat_checkentry(const char *tablename,
	154	const void *entry,
	155	const struct xt_target *target,
	156	void *targinfo,
	157	unsigned int hook_mask)
5b1158e9 JK	158	{
	159	struct nf_nat_multi_range_compat *mr = targinfo;
	160
	161	/* Must be a valid range */
	162	if (mr->rangesize != 1) {
	163	printk("DNAT: multiple ranges no longer supported\n");
e1931b78	164	return false;
5b1158e9	165	}
e1931b78	166	return true;
5b1158e9 JK	167	}
5b1158e9 JK	168
170b197c	169	unsigned int
ba4c7cba	170	alloc_null_binding(struct nf_conn *ct, unsigned int hooknum)
5b1158e9 JK	171	{
	172	/* Force range to this IP; let proto decide mapping for
	173	per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
	174	Use reply in case it's already been mangled (eg local packet).
	175	*/
	176	__be32 ip
	177	= (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
	178	? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip
	179	: ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip);
	180	struct nf_nat_range range
	181	= { IP_NAT_RANGE_MAP_IPS, ip, ip, { 0 }, { 0 } };
	182
0d53778e PM	183	pr_debug("Allocating NULL binding for %p (%u.%u.%u.%u)\n",
0d53778e PM	184	ct, NIPQUAD(ip));
5b1158e9 JK	185	return nf_nat_setup_info(ct, &range, hooknum);
	186	}
	187
	188	unsigned int
ba4c7cba	189	alloc_null_binding_confirmed(struct nf_conn *ct, unsigned int hooknum)
5b1158e9 JK	190	{
	191	__be32 ip
	192	= (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
	193	? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip
	194	: ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip);
a34c4589	195	__be16 all
5b1158e9 JK	196	= (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
	197	? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u.all
	198	: ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u.all);
	199	struct nf_nat_range range
	200	= { IP_NAT_RANGE_MAP_IPS, ip, ip, { all }, { all } };
	201
0d53778e PM	202	pr_debug("Allocating NULL binding for confirmed %p (%u.%u.%u.%u)\n",
0d53778e PM	203	ct, NIPQUAD(ip));
5b1158e9 JK	204	return nf_nat_setup_info(ct, &range, hooknum);
	205	}
	206
	207	int nf_nat_rule_find(struct sk_buff **pskb,
	208	unsigned int hooknum,
	209	const struct net_device *in,
	210	const struct net_device *out,
ba4c7cba	211	struct nf_conn *ct)
5b1158e9 JK	212	{
	213	int ret;
	214
	215	ret = ipt_do_table(pskb, hooknum, in, out, &nat_table);
	216
	217	if (ret == NF_ACCEPT) {
	218	if (!nf_nat_initialized(ct, HOOK2MANIP(hooknum)))
	219	/* NUL mapping */
ba4c7cba	220	ret = alloc_null_binding(ct, hooknum);
5b1158e9 JK	221	}
	222	return ret;
	223	}
	224
9f15c530	225	static struct xt_target ipt_snat_reg __read_mostly = {
5b1158e9 JK	226	.name = "SNAT",
	227	.target = ipt_snat_target,
	228	.targetsize = sizeof(struct nf_nat_multi_range_compat),
	229	.table = "nat",
	230	.hooks = 1 << NF_IP_POST_ROUTING,
	231	.checkentry = ipt_snat_checkentry,
	232	.family = AF_INET,
	233	};
	234
9f15c530	235	static struct xt_target ipt_dnat_reg __read_mostly = {
5b1158e9 JK	236	.name = "DNAT",
	237	.target = ipt_dnat_target,
	238	.targetsize = sizeof(struct nf_nat_multi_range_compat),
	239	.table = "nat",
	240	.hooks = (1 << NF_IP_PRE_ROUTING) \| (1 << NF_IP_LOCAL_OUT),
	241	.checkentry = ipt_dnat_checkentry,
	242	.family = AF_INET,
	243	};
	244
	245	int __init nf_nat_rule_init(void)
	246	{
	247	int ret;
	248
	249	ret = ipt_register_table(&nat_table, &nat_initial_table.repl);
	250	if (ret != 0)
	251	return ret;
	252	ret = xt_register_target(&ipt_snat_reg);
	253	if (ret != 0)
	254	goto unregister_table;
	255
	256	ret = xt_register_target(&ipt_dnat_reg);
	257	if (ret != 0)
	258	goto unregister_snat;
	259
	260	return ret;
	261
	262	unregister_snat:
	263	xt_unregister_target(&ipt_snat_reg);
	264	unregister_table:
	265	ipt_unregister_table(&nat_table);
	266
	267	return ret;
	268	}
	269
	270	void nf_nat_rule_cleanup(void)
	271	{
	272	xt_unregister_target(&ipt_dnat_reg);
	273	xt_unregister_target(&ipt_snat_reg);
	274	ipt_unregister_table(&nat_table);
	275	}