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- /*
- * 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 (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");
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