blob: 11cf9e9e9222e241cf803a54d376fc9274279447 [file] [log] [blame]
/*
* 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;
ether_addr_copy(eth_hdr(skb)->h_source, info->mac);
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 (ebt_invalid_target(tmp))
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");