net/bridge/netfilter/ebt_redirect.c

   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 ebt_target_redirect(struct sk_buff *skb,
  19    unsigned int hooknr,
  20    const struct net_device *in, const struct net_device *out,
  21    const void *data, unsigned int datalen)
  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 ebt_target_redirect_check(const char *tablename, unsigned int hookmask,
  38    const struct ebt_entry *e, void *data, unsigned int datalen)
  39 {
  40         const struct ebt_redirect_info *info = data;
  41
  42         if (BASE_CHAIN && info->target == EBT_RETURN)
  43                 return false;
  44         CLEAR_BASE_CHAIN_BIT;
  45         if ( (strcmp(tablename, "nat") || hookmask & ~(1 << NF_BR_PRE_ROUTING)) &&
  46              (strcmp(tablename, "broute") || hookmask & ~(1 << NF_BR_BROUTING)) )
  47                 return false;
  48         if (INVALID_TARGET)
  49                 return false;
  50         return true;
  51 }
  52
  53 static struct ebt_target redirect_target __read_mostly = {
  54         .name           = EBT_REDIRECT_TARGET,
  55         .revision       = 0,
  56         .family         = NFPROTO_BRIDGE,
  57         .target         = ebt_target_redirect,
  58         .check          = ebt_target_redirect_check,
  59         .targetsize     = XT_ALIGN(sizeof(struct ebt_redirect_info)),
  60         .me             = THIS_MODULE,
  61 };
  62
  63 static int __init ebt_redirect_init(void)
  64 {
  65         return ebt_register_target(&redirect_target);
  66 }
  67
  68 static void __exit ebt_redirect_fini(void)
  69 {
  70         ebt_unregister_target(&redirect_target);
  71 }
  72
  73 module_init(ebt_redirect_init);
  74 module_exit(ebt_redirect_fini);
  75 MODULE_DESCRIPTION("Ebtables: Packet redirection to localhost");
  76 MODULE_LICENSE("GPL");