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   1 /*
   2  *  ebt_redirect
   3  *
   4  *      Authors:
   5  *      Bart De Schuymer <bdschuym@pandora.be>
   6  *
   7  *  April, 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_redirect.h>
  17
  18 static unsigned int
  19 ebt_redirect_tg(struct sk_buff *skb, const struct net_device *in,
  20                 const struct net_device *out, unsigned int hooknr,
  21                 const struct xt_target *target, const void *data)
  22 {
  23         const struct ebt_redirect_info *info = data;
  24
  25         if (!skb_make_writable(skb, 0))
  26                 return EBT_DROP;
  27
  28         if (hooknr != NF_BR_BROUTING)
  29                 memcpy(eth_hdr(skb)->h_dest,
  30                        in->br_port->br->dev->dev_addr, ETH_ALEN);
  31         else
  32                 memcpy(eth_hdr(skb)->h_dest, in->dev_addr, ETH_ALEN);
  33         skb->pkt_type = PACKET_HOST;
  34         return info->target;
  35 }
  36
  37 static bool
  38 ebt_redirect_tg_check(const char *tablename, const void *e,
  39                       const struct xt_target *target, void *data,
  40                       unsigned int hookmask)
  41 {
  42         const struct ebt_redirect_info *info = data;
  43
  44         if (BASE_CHAIN && info->target == EBT_RETURN)
  45                 return false;
  46         CLEAR_BASE_CHAIN_BIT;
  47         if ( (strcmp(tablename, "nat") || hookmask & ~(1 << NF_BR_PRE_ROUTING)) &&
  48              (strcmp(tablename, "broute") || hookmask & ~(1 << NF_BR_BROUTING)) )
  49                 return false;
  50         if (INVALID_TARGET)
  51                 return false;
  52         return true;
  53 }
  54
  55 static struct xt_target ebt_redirect_tg_reg __read_mostly = {
  56         .name           = "redirect",
  57         .revision       = 0,
  58         .family         = NFPROTO_BRIDGE,
  59         .hooks          = (1 << NF_BR_NUMHOOKS) | (1 << NF_BR_PRE_ROUTING) |
  60                           (1 << NF_BR_BROUTING),
  61         .target         = ebt_redirect_tg,
  62         .checkentry     = ebt_redirect_tg_check,
  63         .targetsize     = XT_ALIGN(sizeof(struct ebt_redirect_info)),
  64         .me             = THIS_MODULE,
  65 };
  66
  67 static int __init ebt_redirect_init(void)
  68 {
  69         return xt_register_target(&ebt_redirect_tg_reg);
  70 }
  71
  72 static void __exit ebt_redirect_fini(void)
  73 {
  74         xt_unregister_target(&ebt_redirect_tg_reg);
  75 }
  76
  77 module_init(ebt_redirect_init);
  78 module_exit(ebt_redirect_fini);
  79 MODULE_DESCRIPTION("Ebtables: Packet redirection to localhost");
  80 MODULE_LICENSE("GPL");