net/bridge/netfilter/ebt_dnat.c

   1 /*
   2  *  ebt_dnat
   3  *
   4  *      Authors:
   5  *      Bart De Schuymer <bdschuym@pandora.be>
   6  *
   7  *  June, 2002
   8  *
   9  */
  10 #include <linux/module.h>
  11 #include <net/sock.h>
  12 #include <linux/netfilter.h>
  13 #include <linux/netfilter/x_tables.h>
  14 #include <linux/netfilter_bridge/ebtables.h>
  15 #include <linux/netfilter_bridge/ebt_nat.h>
  16
  17 static unsigned int ebt_target_dnat(struct sk_buff *skb, unsigned int hooknr,
  18    const struct net_device *in, const struct net_device *out,
  19    const void *data, unsigned int datalen)
  20 {
  21         const struct ebt_nat_info *info = data;
  22
  23         if (!skb_make_writable(skb, 0))
  24                 return EBT_DROP;
  25
  26         memcpy(eth_hdr(skb)->h_dest, info->mac, ETH_ALEN);
  27         return info->target;
  28 }
  29
  30 static bool ebt_target_dnat_check(const char *tablename, unsigned int hookmask,
  31    const struct ebt_entry *e, void *data, unsigned int datalen)
  32 {
  33         const struct ebt_nat_info *info = data;
  34
  35         if (BASE_CHAIN && info->target == EBT_RETURN)
  36                 return false;
  37         CLEAR_BASE_CHAIN_BIT;
  38         if ( (strcmp(tablename, "nat") ||
  39            (hookmask & ~((1 << NF_BR_PRE_ROUTING) | (1 << NF_BR_LOCAL_OUT)))) &&
  40            (strcmp(tablename, "broute") || hookmask & ~(1 << NF_BR_BROUTING)) )
  41                 return false;
  42         if (INVALID_TARGET)
  43                 return false;
  44         return true;
  45 }
  46
  47 static struct ebt_target dnat __read_mostly = {
  48         .name           = EBT_DNAT_TARGET,
  49         .target         = ebt_target_dnat,
  50         .check          = ebt_target_dnat_check,
  51         .targetsize     = XT_ALIGN(sizeof(struct ebt_nat_info)),
  52         .me             = THIS_MODULE,
  53 };
  54
  55 static int __init ebt_dnat_init(void)
  56 {
  57         return ebt_register_target(&dnat);
  58 }
  59
  60 static void __exit ebt_dnat_fini(void)
  61 {
  62         ebt_unregister_target(&dnat);
  63 }
  64
  65 module_init(ebt_dnat_init);
  66 module_exit(ebt_dnat_fini);
  67 MODULE_DESCRIPTION("Ebtables: Destination MAC address translation");
  68 MODULE_LICENSE("GPL");