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
  23         if (!skb_make_writable(skb, 0))
  24                 return EBT_DROP;
  25
  26         ether_addr_copy(eth_hdr(skb)->h_dest, info->mac);
  27
  28         if (is_multicast_ether_addr(info->mac)) {
  29                 if (is_broadcast_ether_addr(info->mac))
  30                         skb->pkt_type = PACKET_BROADCAST;
  31                 else
  32                         skb->pkt_type = PACKET_MULTICAST;
  33         } else {
  34                 const struct net_device *dev;
  35
  36                 switch (xt_hooknum(par)) {
  37                 case NF_BR_BROUTING:
  38                         dev = xt_in(par);
  39                         break;
  40                 case NF_BR_PRE_ROUTING:
  41                         dev = br_port_get_rcu(xt_in(par))->br->dev;
  42                         break;
  43                 default:
  44                         dev = NULL;
  45                         break;
  46                 }
  47
  48                 if (!dev) /* NF_BR_LOCAL_OUT */
  49                         return info->target;
  50
  51                 if (ether_addr_equal(info->mac, dev->dev_addr))
  52                         skb->pkt_type = PACKET_HOST;
  53                 else
  54                         skb->pkt_type = PACKET_OTHERHOST;
  55         }
  56
  57         return info->target;
  58 }
  59
  60 static int ebt_dnat_tg_check(const struct xt_tgchk_param *par)
  61 {
  62         const struct ebt_nat_info *info = par->targinfo;
  63         unsigned int hook_mask;
  64
  65         if (BASE_CHAIN && info->target == EBT_RETURN)
  66                 return -EINVAL;
  67
  68         hook_mask = par->hook_mask & ~(1 << NF_BR_NUMHOOKS);
  69         if ((strcmp(par->table, "nat") != 0 ||
  70             (hook_mask & ~((1 << NF_BR_PRE_ROUTING) |
  71             (1 << NF_BR_LOCAL_OUT)))) &&
  72             (strcmp(par->table, "broute") != 0 ||
  73             hook_mask & ~(1 << NF_BR_BROUTING)))
  74                 return -EINVAL;
  75         if (ebt_invalid_target(info->target))
  76                 return -EINVAL;
  77         return 0;
  78 }
  79
  80 static struct xt_target ebt_dnat_tg_reg __read_mostly = {
  81         .name           = "dnat",
  82         .revision       = 0,
  83         .family         = NFPROTO_BRIDGE,
  84         .hooks          = (1 << NF_BR_NUMHOOKS) | (1 << NF_BR_PRE_ROUTING) |
  85                           (1 << NF_BR_LOCAL_OUT) | (1 << NF_BR_BROUTING),
  86         .target         = ebt_dnat_tg,
  87         .checkentry     = ebt_dnat_tg_check,
  88         .targetsize     = sizeof(struct ebt_nat_info),
  89         .me             = THIS_MODULE,
  90 };
  91
  92 static int __init ebt_dnat_init(void)
  93 {
  94         return xt_register_target(&ebt_dnat_tg_reg);
  95 }
  96
  97 static void __exit ebt_dnat_fini(void)
  98 {
  99         xt_unregister_target(&ebt_dnat_tg_reg);
 100 }
 101
 102 module_init(ebt_dnat_init);
 103 module_exit(ebt_dnat_fini);
 104 MODULE_DESCRIPTION("Ebtables: Destination MAC address translation");
 105 MODULE_LICENSE("GPL");