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 "../br_private.h"
  13 #include <linux/netfilter.h>
  14 #include <linux/netfilter/x_tables.h>
  15 #include <linux/netfilter_bridge/ebtables.h>
  16 #include <linux/netfilter_bridge/ebt_nat.h>
  17
  18 static unsigned int
  19 ebt_dnat_tg(struct sk_buff *skb, const struct xt_action_param *par)
  20 {
  21         const struct ebt_nat_info *info = par->targinfo;
  22         struct net_device *dev;
  23
  24         if (!skb_make_writable(skb, 0))
  25                 return EBT_DROP;
  26
  27         ether_addr_copy(eth_hdr(skb)->h_dest, info->mac);
  28
  29         if (is_multicast_ether_addr(info->mac)) {
  30                 if (is_broadcast_ether_addr(info->mac))
  31                         skb->pkt_type = PACKET_BROADCAST;
  32                 else
  33                         skb->pkt_type = PACKET_MULTICAST;
  34         } else {
  35                 if (xt_hooknum(par) != NF_BR_BROUTING)
  36                         dev = br_port_get_rcu(xt_in(par))->br->dev;
  37                 else
  38                         dev = xt_in(par);
  39
  40                 if (ether_addr_equal(info->mac, dev->dev_addr))
  41                         skb->pkt_type = PACKET_HOST;
  42                 else
  43                         skb->pkt_type = PACKET_OTHERHOST;
  44         }
  45
  46         return info->target;
  47 }
  48
  49 static int ebt_dnat_tg_check(const struct xt_tgchk_param *par)
  50 {
  51         const struct ebt_nat_info *info = par->targinfo;
  52         unsigned int hook_mask;
  53
  54         if (BASE_CHAIN && info->target == EBT_RETURN)
  55                 return -EINVAL;
  56
  57         hook_mask = par->hook_mask & ~(1 << NF_BR_NUMHOOKS);
  58         if ((strcmp(par->table, "nat") != 0 ||
  59             (hook_mask & ~((1 << NF_BR_PRE_ROUTING) |
  60             (1 << NF_BR_LOCAL_OUT)))) &&
  61             (strcmp(par->table, "broute") != 0 ||
  62             hook_mask & ~(1 << NF_BR_BROUTING)))
  63                 return -EINVAL;
  64         if (ebt_invalid_target(info->target))
  65                 return -EINVAL;
  66         return 0;
  67 }
  68
  69 static struct xt_target ebt_dnat_tg_reg __read_mostly = {
  70         .name           = "dnat",
  71         .revision       = 0,
  72         .family         = NFPROTO_BRIDGE,
  73         .hooks          = (1 << NF_BR_NUMHOOKS) | (1 << NF_BR_PRE_ROUTING) |
  74                           (1 << NF_BR_LOCAL_OUT) | (1 << NF_BR_BROUTING),
  75         .target         = ebt_dnat_tg,
  76         .checkentry     = ebt_dnat_tg_check,
  77         .targetsize     = sizeof(struct ebt_nat_info),
  78         .me             = THIS_MODULE,
  79 };
  80
  81 static int __init ebt_dnat_init(void)
  82 {
  83         return xt_register_target(&ebt_dnat_tg_reg);
  84 }
  85
  86 static void __exit ebt_dnat_fini(void)
  87 {
  88         xt_unregister_target(&ebt_dnat_tg_reg);
  89 }
  90
  91 module_init(ebt_dnat_init);
  92 module_exit(ebt_dnat_fini);
  93 MODULE_DESCRIPTION("Ebtables: Destination MAC address translation");
  94 MODULE_LICENSE("GPL");