5 * Bart De Schuymer <bdschuym@pandora.be>
10 #include <linux/module.h>
12 #include <linux/if_arp.h>
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>
19 static unsigned int ebt_target_snat(struct sk_buff *skb, unsigned int hooknr,
20 const struct net_device *in, const struct net_device *out,
21 const void *data, unsigned int datalen)
23 const struct ebt_nat_info *info = data;
25 if (!skb_make_writable(skb, 0))
28 memcpy(eth_hdr(skb)->h_source, info->mac, ETH_ALEN);
29 if (!(info->target & NAT_ARP_BIT) &&
30 eth_hdr(skb)->h_proto == htons(ETH_P_ARP)) {
31 const struct arphdr *ap;
34 ap = skb_header_pointer(skb, 0, sizeof(_ah), &_ah);
37 if (ap->ar_hln != ETH_ALEN)
39 if (skb_store_bits(skb, sizeof(_ah), info->mac,ETH_ALEN))
43 return info->target | ~EBT_VERDICT_BITS;
46 static bool ebt_target_snat_check(const char *tablename, unsigned int hookmask,
47 const struct ebt_entry *e, void *data, unsigned int datalen)
49 const struct ebt_nat_info *info = data;
52 tmp = info->target | ~EBT_VERDICT_BITS;
53 if (BASE_CHAIN && tmp == EBT_RETURN)
56 if (strcmp(tablename, "nat"))
58 if (hookmask & ~(1 << NF_BR_POST_ROUTING))
61 if (tmp < -NUM_STANDARD_TARGETS || tmp >= 0)
63 tmp = info->target | EBT_VERDICT_BITS;
64 if ((tmp & ~NAT_ARP_BIT) != ~NAT_ARP_BIT)
69 static struct ebt_target snat __read_mostly = {
70 .name = EBT_SNAT_TARGET,
72 .family = NFPROTO_BRIDGE,
73 .target = ebt_target_snat,
74 .check = ebt_target_snat_check,
75 .targetsize = XT_ALIGN(sizeof(struct ebt_nat_info)),
79 static int __init ebt_snat_init(void)
81 return ebt_register_target(&snat);
84 static void __exit ebt_snat_fini(void)
86 ebt_unregister_target(&snat);
89 module_init(ebt_snat_init);
90 module_exit(ebt_snat_fini);
91 MODULE_DESCRIPTION("Ebtables: Source MAC address translation");
92 MODULE_LICENSE("GPL");