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/*
* ebt_snat
*
* Authors:
* Bart De Schuymer <bdschuym@pandora.be>
*
* June, 2002
*
*/
#include <linux/netfilter.h>
#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 *skb, 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_make_writable(skb, 0))
return NF_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)) {
struct arphdr _ah, *ap;
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_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");
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