[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>

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

#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 int 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 0;
	}
	return 1;
}

static int 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 0;
	}
	return 1;
}

inline 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 } };

	DEBUGP("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);
	u_int16_t 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 } };

	DEBUGP("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 = {
	.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 = {
	.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
	27	#if 0
	28	#define DEBUGP printk
	29	#else
	30	#define DEBUGP(format, args...)
	31	#endif
	32
	33	#define NAT_VALID_HOOKS ((1<<NF_IP_PRE_ROUTING) \| (1<<NF_IP_POST_ROUTING) \| (1<<NF_IP_LOCAL_OUT))
	34
	35	static struct
	36	{
	37	struct ipt_replace repl;
	38	struct ipt_standard entries[3];
	39	struct ipt_error term;
	40	} nat_initial_table __initdata = {
	41	.repl = {
	42	.name = "nat",
	43	.valid_hooks = NAT_VALID_HOOKS,
	44	.num_entries = 4,
	45	.size = sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error),
	46	.hook_entry = {
	47	[NF_IP_PRE_ROUTING] = 0,
	48	[NF_IP_POST_ROUTING] = sizeof(struct ipt_standard),
3c2ad469 PM	49	[NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2
3c2ad469 PM	50	},
5b1158e9 JK	51	.underflow = {
	52	[NF_IP_PRE_ROUTING] = 0,
	53	[NF_IP_POST_ROUTING] = sizeof(struct ipt_standard),
3c2ad469 PM	54	[NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2
3c2ad469 PM	55	},
5b1158e9 JK	56	},
5b1158e9 JK	57	.entries = {
3c2ad469 PM	58	IPT_STANDARD_INIT(NF_ACCEPT), /* PRE_ROUTING */
	59	IPT_STANDARD_INIT(NF_ACCEPT), /* POST_ROUTING */
	60	IPT_STANDARD_INIT(NF_ACCEPT), /* LOCAL_OUT */
5b1158e9	61	},
3c2ad469	62	.term = IPT_ERROR_INIT, /* ERROR */
5b1158e9 JK	63	};
5b1158e9 JK	64
e60a13e0	65	static struct xt_table nat_table = {
5b1158e9 JK	66	.name = "nat",
	67	.valid_hooks = NAT_VALID_HOOKS,
	68	.lock = RW_LOCK_UNLOCKED,
	69	.me = THIS_MODULE,
	70	.af = AF_INET,
	71	};
	72
	73	/* Source NAT */
	74	static unsigned int ipt_snat_target(struct sk_buff **pskb,
	75	const struct net_device *in,
	76	const struct net_device *out,
	77	unsigned int hooknum,
	78	const struct xt_target *target,
	79	const void *targinfo)
	80	{
	81	struct nf_conn *ct;
	82	enum ip_conntrack_info ctinfo;
	83	const struct nf_nat_multi_range_compat *mr = targinfo;
	84
	85	NF_CT_ASSERT(hooknum == NF_IP_POST_ROUTING);
	86
	87	ct = nf_ct_get(*pskb, &ctinfo);
	88
	89	/* Connection must be valid and new. */
	90	NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW \|\| ctinfo == IP_CT_RELATED \|\|
e905a9ed	91	ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY));
5b1158e9 JK	92	NF_CT_ASSERT(out);
	93
	94	return nf_nat_setup_info(ct, &mr->range[0], hooknum);
	95	}
	96
	97	/* Before 2.6.11 we did implicit source NAT if required. Warn about change. */
	98	static void warn_if_extra_mangle(__be32 dstip, __be32 srcip)
	99	{
	100	static int warned = 0;
	101	struct flowi fl = { .nl_u = { .ip4_u = { .daddr = dstip } } };
	102	struct rtable *rt;
	103
	104	if (ip_route_output_key(&rt, &fl) != 0)
	105	return;
	106
	107	if (rt->rt_src != srcip && !warned) {
	108	printk("NAT: no longer support implicit source local NAT\n");
	109	printk("NAT: packet src %u.%u.%u.%u -> dst %u.%u.%u.%u\n",
	110	NIPQUAD(srcip), NIPQUAD(dstip));
	111	warned = 1;
	112	}
	113	ip_rt_put(rt);
	114	}
	115
	116	static unsigned int ipt_dnat_target(struct sk_buff **pskb,
	117	const struct net_device *in,
	118	const struct net_device *out,
	119	unsigned int hooknum,
	120	const struct xt_target *target,
	121	const void *targinfo)
	122	{
	123	struct nf_conn *ct;
	124	enum ip_conntrack_info ctinfo;
	125	const struct nf_nat_multi_range_compat *mr = targinfo;
	126
	127	NF_CT_ASSERT(hooknum == NF_IP_PRE_ROUTING \|\|
	128	hooknum == NF_IP_LOCAL_OUT);
	129
	130	ct = nf_ct_get(*pskb, &ctinfo);
	131
	132	/* Connection must be valid and new. */
	133	NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW \|\| ctinfo == IP_CT_RELATED));
	134
	135	if (hooknum == NF_IP_LOCAL_OUT &&
	136	mr->range[0].flags & IP_NAT_RANGE_MAP_IPS)
eddc9ec5	137	warn_if_extra_mangle(ip_hdr(*pskb)->daddr,
5b1158e9 JK	138	mr->range[0].min_ip);
	139
	140	return nf_nat_setup_info(ct, &mr->range[0], hooknum);
	141	}
	142
	143	static int ipt_snat_checkentry(const char *tablename,
	144	const void *entry,
	145	const struct xt_target *target,
	146	void *targinfo,
	147	unsigned int hook_mask)
	148	{
	149	struct nf_nat_multi_range_compat *mr = targinfo;
	150
	151	/* Must be a valid range */
	152	if (mr->rangesize != 1) {
	153	printk("SNAT: multiple ranges no longer supported\n");
	154	return 0;
	155	}
	156	return 1;
	157	}
	158
	159	static int ipt_dnat_checkentry(const char *tablename,
	160	const void *entry,
	161	const struct xt_target *target,
	162	void *targinfo,
	163	unsigned int hook_mask)
	164	{
	165	struct nf_nat_multi_range_compat *mr = targinfo;
	166
	167	/* Must be a valid range */
	168	if (mr->rangesize != 1) {
	169	printk("DNAT: multiple ranges no longer supported\n");
	170	return 0;
	171	}
	172	return 1;
	173	}
	174
	175	inline unsigned int
ba4c7cba	176	alloc_null_binding(struct nf_conn *ct, unsigned int hooknum)
5b1158e9 JK	177	{
	178	/* Force range to this IP; let proto decide mapping for
	179	per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
	180	Use reply in case it's already been mangled (eg local packet).
	181	*/
	182	__be32 ip
	183	= (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
	184	? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip
	185	: ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip);
	186	struct nf_nat_range range
	187	= { IP_NAT_RANGE_MAP_IPS, ip, ip, { 0 }, { 0 } };
	188
	189	DEBUGP("Allocating NULL binding for %p (%u.%u.%u.%u)\n",
	190	ct, NIPQUAD(ip));
	191	return nf_nat_setup_info(ct, &range, hooknum);
	192	}
	193
	194	unsigned int
ba4c7cba	195	alloc_null_binding_confirmed(struct nf_conn *ct, unsigned int hooknum)
5b1158e9 JK	196	{
	197	__be32 ip
	198	= (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
	199	? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip
	200	: ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip);
	201	u_int16_t all
	202	= (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
	203	? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u.all
	204	: ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u.all);
	205	struct nf_nat_range range
	206	= { IP_NAT_RANGE_MAP_IPS, ip, ip, { all }, { all } };
	207
	208	DEBUGP("Allocating NULL binding for confirmed %p (%u.%u.%u.%u)\n",
	209	ct, NIPQUAD(ip));
	210	return nf_nat_setup_info(ct, &range, hooknum);
	211	}
	212
	213	int nf_nat_rule_find(struct sk_buff **pskb,
	214	unsigned int hooknum,
	215	const struct net_device *in,
	216	const struct net_device *out,
ba4c7cba	217	struct nf_conn *ct)
5b1158e9 JK	218	{
	219	int ret;
	220
	221	ret = ipt_do_table(pskb, hooknum, in, out, &nat_table);
	222
	223	if (ret == NF_ACCEPT) {
	224	if (!nf_nat_initialized(ct, HOOK2MANIP(hooknum)))
	225	/* NUL mapping */
ba4c7cba	226	ret = alloc_null_binding(ct, hooknum);
5b1158e9 JK	227	}
	228	return ret;
	229	}
	230
6709dbbb	231	static struct xt_target ipt_snat_reg = {
5b1158e9 JK	232	.name = "SNAT",
	233	.target = ipt_snat_target,
	234	.targetsize = sizeof(struct nf_nat_multi_range_compat),
	235	.table = "nat",
	236	.hooks = 1 << NF_IP_POST_ROUTING,
	237	.checkentry = ipt_snat_checkentry,
	238	.family = AF_INET,
	239	};
	240
	241	static struct xt_target ipt_dnat_reg = {
	242	.name = "DNAT",
	243	.target = ipt_dnat_target,
	244	.targetsize = sizeof(struct nf_nat_multi_range_compat),
	245	.table = "nat",
	246	.hooks = (1 << NF_IP_PRE_ROUTING) \| (1 << NF_IP_LOCAL_OUT),
	247	.checkentry = ipt_dnat_checkentry,
	248	.family = AF_INET,
	249	};
	250
	251	int __init nf_nat_rule_init(void)
	252	{
	253	int ret;
	254
	255	ret = ipt_register_table(&nat_table, &nat_initial_table.repl);
	256	if (ret != 0)
	257	return ret;
	258	ret = xt_register_target(&ipt_snat_reg);
	259	if (ret != 0)
	260	goto unregister_table;
	261
	262	ret = xt_register_target(&ipt_dnat_reg);
	263	if (ret != 0)
	264	goto unregister_snat;
	265
	266	return ret;
	267
	268	unregister_snat:
	269	xt_unregister_target(&ipt_snat_reg);
	270	unregister_table:
	271	ipt_unregister_table(&nat_table);
	272
	273	return ret;
	274	}
	275
	276	void nf_nat_rule_cleanup(void)
	277	{
	278	xt_unregister_target(&ipt_dnat_reg);
	279	xt_unregister_target(&ipt_snat_reg);
	280	ipt_unregister_table(&nat_table);
	281	}