[net-next-2.6.git] / net / bridge / netfilter / ebt_snat.c

/*
 *  ebt_snat
 *
 *	Authors:
 *	Bart De Schuymer <bdschuym@pandora.be>
 *
 *  June, 2002
 *
 */
#include <linux/module.h>
#include <net/sock.h>
#include <linux/if_arp.h>
#include <net/arp.h>
#include <linux/netfilter.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_bridge/ebtables.h>
#include <linux/netfilter_bridge/ebt_nat.h>

static unsigned int
ebt_snat_tg(struct sk_buff *skb, const struct xt_action_param *par)
{
	const struct ebt_nat_info *info = par->targinfo;

	if (!skb_make_writable(skb, 0))
		return EBT_DROP;

	memcpy(eth_hdr(skb)->h_source, info->mac, ETH_ALEN);
	if (!(info->target & NAT_ARP_BIT) &&
	    eth_hdr(skb)->h_proto == htons(ETH_P_ARP)) {
		const struct arphdr *ap;
		struct arphdr _ah;

		ap = skb_header_pointer(skb, 0, sizeof(_ah), &_ah);
		if (ap == NULL)
			return EBT_DROP;
		if (ap->ar_hln != ETH_ALEN)
			goto out;
		if (skb_store_bits(skb, sizeof(_ah), info->mac,ETH_ALEN))
			return EBT_DROP;
	}
out:
	return info->target | ~EBT_VERDICT_BITS;
}

static int ebt_snat_tg_check(const struct xt_tgchk_param *par)
{
	const struct ebt_nat_info *info = par->targinfo;
	int tmp;

	tmp = info->target | ~EBT_VERDICT_BITS;
	if (BASE_CHAIN && tmp == EBT_RETURN)
		return -EINVAL;

	if (tmp < -NUM_STANDARD_TARGETS || tmp >= 0)
		return -EINVAL;
	tmp = info->target | EBT_VERDICT_BITS;
	if ((tmp & ~NAT_ARP_BIT) != ~NAT_ARP_BIT)
		return -EINVAL;
	return 0;
}

static struct xt_target ebt_snat_tg_reg __read_mostly = {
	.name		= "snat",
	.revision	= 0,
	.family		= NFPROTO_BRIDGE,
	.table		= "nat",
	.hooks		= (1 << NF_BR_NUMHOOKS) | (1 << NF_BR_POST_ROUTING),
	.target		= ebt_snat_tg,
	.checkentry	= ebt_snat_tg_check,
	.targetsize	= sizeof(struct ebt_nat_info),
	.me		= THIS_MODULE,
};

static int __init ebt_snat_init(void)
{
	return xt_register_target(&ebt_snat_tg_reg);
}

static void __exit ebt_snat_fini(void)
{
	xt_unregister_target(&ebt_snat_tg_reg);
}

module_init(ebt_snat_init);
module_exit(ebt_snat_fini);
MODULE_DESCRIPTION("Ebtables: Source MAC address translation");
MODULE_LICENSE("GPL");
Commit	Line	Data
1da177e4 LT	1	/*
	2	* ebt_snat
	3	*
	4	* Authors:
	5	* Bart De Schuymer <bdschuym@pandora.be>
	6	*
	7	* June, 2002
	8	*
	9	*/
1da177e4 LT	10	#include <linux/module.h>
1da177e4 LT	11	#include <net/sock.h>
d12cdc3c BDS	12	#include <linux/if_arp.h>
d12cdc3c BDS	13	#include <net/arp.h>
18219d3f JE	14	#include <linux/netfilter.h>
	15	#include <linux/netfilter/x_tables.h>
	16	#include <linux/netfilter_bridge/ebtables.h>
	17	#include <linux/netfilter_bridge/ebt_nat.h>
1da177e4	18
2d06d4a5	19	static unsigned int
4b560b44	20	ebt_snat_tg(struct sk_buff skb, const struct xt_action_param par)
1da177e4	21	{
7eb35586	22	const struct ebt_nat_info *info = par->targinfo;
1da177e4	23
eb1197bc	24	if (!skb_make_writable(skb, 0))
1b04ab45	25	return EBT_DROP;
1da177e4	26
3db05fea	27	memcpy(eth_hdr(skb)->h_source, info->mac, ETH_ALEN);
d12cdc3c	28	if (!(info->target & NAT_ARP_BIT) &&
3db05fea	29	eth_hdr(skb)->h_proto == htons(ETH_P_ARP)) {
abfdf1c4 JE	30	const struct arphdr *ap;
abfdf1c4 JE	31	struct arphdr _ah;
d12cdc3c	32
3db05fea	33	ap = skb_header_pointer(skb, 0, sizeof(_ah), &_ah);
d12cdc3c BDS	34	if (ap == NULL)
	35	return EBT_DROP;
	36	if (ap->ar_hln != ETH_ALEN)
	37	goto out;
3db05fea	38	if (skb_store_bits(skb, sizeof(_ah), info->mac,ETH_ALEN))
d12cdc3c BDS	39	return EBT_DROP;
	40	}
	41	out:
	42	return info->target \| ~EBT_VERDICT_BITS;
1da177e4 LT	43	}
1da177e4 LT	44
135367b8	45	static int ebt_snat_tg_check(const struct xt_tgchk_param *par)
1da177e4	46	{
af5d6dc2	47	const struct ebt_nat_info *info = par->targinfo;
d12cdc3c	48	int tmp;
1da177e4	49
d12cdc3c BDS	50	tmp = info->target \| ~EBT_VERDICT_BITS;
d12cdc3c BDS	51	if (BASE_CHAIN && tmp == EBT_RETURN)
d6b00a53	52	return -EINVAL;
d12cdc3c BDS	53
d12cdc3c BDS	54	if (tmp < -NUM_STANDARD_TARGETS \|\| tmp >= 0)
d6b00a53	55	return -EINVAL;
d12cdc3c BDS	56	tmp = info->target \| EBT_VERDICT_BITS;
d12cdc3c BDS	57	if ((tmp & ~NAT_ARP_BIT) != ~NAT_ARP_BIT)
d6b00a53 JE	58	return -EINVAL;
d6b00a53 JE	59	return 0;
1da177e4 LT	60	}
1da177e4 LT	61
043ef46c JE	62	static struct xt_target ebt_snat_tg_reg __read_mostly = {
043ef46c JE	63	.name = "snat",
001a18d3 JE	64	.revision = 0,
001a18d3 JE	65	.family = NFPROTO_BRIDGE,
f2ff525c JE	66	.table = "nat",
f2ff525c JE	67	.hooks = (1 << NF_BR_NUMHOOKS) \| (1 << NF_BR_POST_ROUTING),
2d06d4a5 JE	68	.target = ebt_snat_tg,
2d06d4a5 JE	69	.checkentry = ebt_snat_tg_check,
fc0e3df4	70	.targetsize = sizeof(struct ebt_nat_info),
1da177e4 LT	71	.me = THIS_MODULE,
	72	};
	73
65b4b4e8	74	static int __init ebt_snat_init(void)
1da177e4	75	{
043ef46c	76	return xt_register_target(&ebt_snat_tg_reg);
1da177e4 LT	77	}
1da177e4 LT	78
65b4b4e8	79	static void __exit ebt_snat_fini(void)
1da177e4	80	{
043ef46c	81	xt_unregister_target(&ebt_snat_tg_reg);
1da177e4 LT	82	}
1da177e4 LT	83
65b4b4e8 AM	84	module_init(ebt_snat_init);
65b4b4e8 AM	85	module_exit(ebt_snat_fini);
f776c4cd	86	MODULE_DESCRIPTION("Ebtables: Source MAC address translation");
1da177e4	87	MODULE_LICENSE("GPL");