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
  18 ebt_dnat_tg(struct sk_buff *skb, const struct xt_target_param *par)
  19 {
  20         const struct ebt_nat_info *info = par->targinfo;
  21
  22         if (!skb_make_writable(skb, 0))
  23                 return EBT_DROP;
  24
  25         memcpy(eth_hdr(skb)->h_dest, info->mac, ETH_ALEN);
  26         return info->target;
  27 }
  28
  29 static bool ebt_dnat_tg_check(const struct xt_tgchk_param *par)
  30 {
  31         const struct ebt_nat_info *info = par->targinfo;
  32         unsigned int hook_mask;
  33
  34         if (BASE_CHAIN && info->target == EBT_RETURN)
  35                 return false;
  36
  37         hook_mask = par->hook_mask & ~(1 << NF_BR_NUMHOOKS);
  38         if ((strcmp(par->table, "nat") != 0 ||
  39             (hook_mask & ~((1 << NF_BR_PRE_ROUTING) |
  40             (1 << NF_BR_LOCAL_OUT)))) &&
  41             (strcmp(par->table, "broute") != 0 ||
  42             hook_mask & ~(1 << NF_BR_BROUTING)))
  43                 return false;
  44         if (INVALID_TARGET)
  45                 return false;
  46         return true;
  47 }
  48
  49 static struct xt_target ebt_dnat_tg_reg __read_mostly = {
  50         .name           = "dnat",
  51         .revision       = 0,
  52         .family         = NFPROTO_BRIDGE,
  53         .hooks          = (1 << NF_BR_NUMHOOKS) | (1 << NF_BR_PRE_ROUTING) |
  54                           (1 << NF_BR_LOCAL_OUT) | (1 << NF_BR_BROUTING),
  55         .target         = ebt_dnat_tg,
  56         .checkentry     = ebt_dnat_tg_check,
  57         .targetsize     = XT_ALIGN(sizeof(struct ebt_nat_info)),
  58         .me             = THIS_MODULE,
  59 };
  60
  61 static int __init ebt_dnat_init(void)
  62 {
  63         return xt_register_target(&ebt_dnat_tg_reg);
  64 }
  65
  66 static void __exit ebt_dnat_fini(void)
  67 {
  68         xt_unregister_target(&ebt_dnat_tg_reg);
  69 }
  70
  71 module_init(ebt_dnat_init);
  72 module_exit(ebt_dnat_fini);
  73 MODULE_DESCRIPTION("Ebtables: Destination MAC address translation");
  74 MODULE_LICENSE("GPL");