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
  11 #include <linux/netfilter.h>
  12 #include <linux/netfilter_bridge/ebtables.h>
  13 #include <linux/netfilter_bridge/ebt_redirect.h>
  14 #include <linux/module.h>
  15 #include <net/sock.h>
  16 #include "../br_private.h"
  17
  18 static int ebt_target_redirect(struct sk_buff *skb, unsigned int hooknr,
  19    const struct net_device *in, const struct net_device *out,
  20    const void *data, unsigned int datalen)
  21 {
  22         const struct ebt_redirect_info *info = data;
  23
  24         if (!skb_make_writable(skb, 0))
  25                 return NF_DROP;
  26
  27         if (hooknr != NF_BR_BROUTING)
  28                 memcpy(eth_hdr(skb)->h_dest,
  29                        in->br_port->br->dev->dev_addr, ETH_ALEN);
  30         else
  31                 memcpy(eth_hdr(skb)->h_dest, in->dev_addr, ETH_ALEN);
  32         skb->pkt_type = PACKET_HOST;
  33         return info->target;
  34 }
  35
  36 static int ebt_target_redirect_check(const char *tablename, unsigned int hookmask,
  37    const struct ebt_entry *e, void *data, unsigned int datalen)
  38 {
  39         const struct ebt_redirect_info *info = data;
  40
  41         if (datalen != EBT_ALIGN(sizeof(struct ebt_redirect_info)))
  42                 return -EINVAL;
  43         if (BASE_CHAIN && info->target == EBT_RETURN)
  44                 return -EINVAL;
  45         CLEAR_BASE_CHAIN_BIT;
  46         if ( (strcmp(tablename, "nat") || hookmask & ~(1 << NF_BR_PRE_ROUTING)) &&
  47              (strcmp(tablename, "broute") || hookmask & ~(1 << NF_BR_BROUTING)) )
  48                 return -EINVAL;
  49         if (INVALID_TARGET)
  50                 return -EINVAL;
  51         return 0;
  52 }
  53
  54 static struct ebt_target redirect_target __read_mostly = {
  55         .name           = EBT_REDIRECT_TARGET,
  56         .target         = ebt_target_redirect,
  57         .check          = ebt_target_redirect_check,
  58         .me             = THIS_MODULE,
  59 };
  60
  61 static int __init ebt_redirect_init(void)
  62 {
  63         return ebt_register_target(&redirect_target);
  64 }
  65
  66 static void __exit ebt_redirect_fini(void)
  67 {
  68         ebt_unregister_target(&redirect_target);
  69 }
  70
  71 module_init(ebt_redirect_init);
  72 module_exit(ebt_redirect_fini);
  73 MODULE_DESCRIPTION("Ebtables: Packet redirection to localhost");
  74 MODULE_LICENSE("GPL");