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

/*
 *  ebt_snat
 *
 *	Authors:
 *	Bart De Schuymer <bdschuym@pandora.be>
 *
 *  June, 2002
 *
 */

#include <linux/netfilter_bridge/ebtables.h>
#include <linux/netfilter_bridge/ebt_nat.h>
#include <linux/module.h>
#include <net/sock.h>
#include <linux/if_arp.h>
#include <net/arp.h>

static int ebt_target_snat(struct sk_buff **pskb, unsigned int hooknr,
   const struct net_device *in, const struct net_device *out,
   const void *data, unsigned int datalen)
{
	struct ebt_nat_info *info = (struct ebt_nat_info *) data;

	if (skb_shared(*pskb) || skb_cloned(*pskb)) {
		struct sk_buff *nskb;

		nskb = skb_copy(*pskb, GFP_ATOMIC);
		if (!nskb)
			return NF_DROP;
		if ((*pskb)->sk)
			skb_set_owner_w(nskb, (*pskb)->sk);
		kfree_skb(*pskb);
		*pskb = nskb;
	}
	memcpy(eth_hdr(*pskb)->h_source, info->mac, ETH_ALEN);
	if (!(info->target & NAT_ARP_BIT) &&
	    eth_hdr(*pskb)->h_proto == htons(ETH_P_ARP)) {
		struct arphdr _ah, *ap;

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

static int ebt_target_snat_check(const char *tablename, unsigned int hookmask,
   const struct ebt_entry *e, void *data, unsigned int datalen)
{
	struct ebt_nat_info *info = (struct ebt_nat_info *) data;
	int tmp;

	if (datalen != EBT_ALIGN(sizeof(struct ebt_nat_info)))
		return -EINVAL;
	tmp = info->target | ~EBT_VERDICT_BITS;
	if (BASE_CHAIN && tmp == EBT_RETURN)
		return -EINVAL;
	CLEAR_BASE_CHAIN_BIT;
	if (strcmp(tablename, "nat"))
		return -EINVAL;
	if (hookmask & ~(1 << NF_BR_POST_ROUTING))
		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 ebt_target snat =
{
	.name		= EBT_SNAT_TARGET,
	.target		= ebt_target_snat,
	.check		= ebt_target_snat_check,
	.me		= THIS_MODULE,
};

static int __init ebt_snat_init(void)
{
	return ebt_register_target(&snat);
}

static void __exit ebt_snat_fini(void)
{
	ebt_unregister_target(&snat);
}

module_init(ebt_snat_init);
module_exit(ebt_snat_fini);
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	*/
	10
	11	#include <linux/netfilter_bridge/ebtables.h>
	12	#include <linux/netfilter_bridge/ebt_nat.h>
	13	#include <linux/module.h>
	14	#include <net/sock.h>
d12cdc3c BDS	15	#include <linux/if_arp.h>
d12cdc3c BDS	16	#include <net/arp.h>
1da177e4 LT	17
	18	static int ebt_target_snat(struct sk_buff **pskb, unsigned int hooknr,
	19	const struct net_device in, const struct net_device out,
	20	const void *data, unsigned int datalen)
	21	{
	22	struct ebt_nat_info info = (struct ebt_nat_info ) data;
	23
	24	if (skb_shared(pskb) \|\| skb_cloned(pskb)) {
	25	struct sk_buff *nskb;
	26
	27	nskb = skb_copy(*pskb, GFP_ATOMIC);
	28	if (!nskb)
	29	return NF_DROP;
	30	if ((*pskb)->sk)
	31	skb_set_owner_w(nskb, (*pskb)->sk);
	32	kfree_skb(*pskb);
	33	*pskb = nskb;
	34	}
	35	memcpy(eth_hdr(*pskb)->h_source, info->mac, ETH_ALEN);
d12cdc3c BDS	36	if (!(info->target & NAT_ARP_BIT) &&
	37	eth_hdr(*pskb)->h_proto == htons(ETH_P_ARP)) {
	38	struct arphdr _ah, *ap;
	39
	40	ap = skb_header_pointer(*pskb, 0, sizeof(_ah), &_ah);
	41	if (ap == NULL)
	42	return EBT_DROP;
	43	if (ap->ar_hln != ETH_ALEN)
	44	goto out;
	45	if (skb_store_bits(*pskb, sizeof(_ah), info->mac,ETH_ALEN))
	46	return EBT_DROP;
	47	}
	48	out:
	49	return info->target \| ~EBT_VERDICT_BITS;
1da177e4 LT	50	}
	51
	52	static int ebt_target_snat_check(const char *tablename, unsigned int hookmask,
	53	const struct ebt_entry e, void data, unsigned int datalen)
	54	{
	55	struct ebt_nat_info info = (struct ebt_nat_info ) data;
d12cdc3c	56	int tmp;
1da177e4 LT	57
	58	if (datalen != EBT_ALIGN(sizeof(struct ebt_nat_info)))
	59	return -EINVAL;
d12cdc3c BDS	60	tmp = info->target \| ~EBT_VERDICT_BITS;
d12cdc3c BDS	61	if (BASE_CHAIN && tmp == EBT_RETURN)
1da177e4 LT	62	return -EINVAL;
	63	CLEAR_BASE_CHAIN_BIT;
	64	if (strcmp(tablename, "nat"))
	65	return -EINVAL;
	66	if (hookmask & ~(1 << NF_BR_POST_ROUTING))
	67	return -EINVAL;
d12cdc3c BDS	68
	69	if (tmp < -NUM_STANDARD_TARGETS \|\| tmp >= 0)
	70	return -EINVAL;
	71	tmp = info->target \| EBT_VERDICT_BITS;
	72	if ((tmp & ~NAT_ARP_BIT) != ~NAT_ARP_BIT)
1da177e4 LT	73	return -EINVAL;
	74	return 0;
	75	}
	76
	77	static struct ebt_target snat =
	78	{
	79	.name = EBT_SNAT_TARGET,
	80	.target = ebt_target_snat,
	81	.check = ebt_target_snat_check,
	82	.me = THIS_MODULE,
	83	};
	84
65b4b4e8	85	static int __init ebt_snat_init(void)
1da177e4 LT	86	{
	87	return ebt_register_target(&snat);
	88	}
	89
65b4b4e8	90	static void __exit ebt_snat_fini(void)
1da177e4 LT	91	{
	92	ebt_unregister_target(&snat);
	93	}
	94
65b4b4e8 AM	95	module_init(ebt_snat_init);
65b4b4e8 AM	96	module_exit(ebt_snat_fini);
1da177e4	97	MODULE_LICENSE("GPL");