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
  19 ebt_redirect_tg(struct sk_buff *skb, const struct xt_action_param *par)
  20 {
  21         const struct ebt_redirect_info *info = par->targinfo;
  22
  23         if (!skb_make_writable(skb, 0))
  24                 return EBT_DROP;
  25
  26         if (par->hooknum != NF_BR_BROUTING)
  27                 /* rcu_read_lock()ed by nf_hook_slow */
  28                 memcpy(eth_hdr(skb)->h_dest,
  29                        br_port_get_rcu(par->in)->br->dev->dev_addr, ETH_ALEN);
  30         else
  31                 memcpy(eth_hdr(skb)->h_dest, par->in->dev_addr, ETH_ALEN);
  32         skb->pkt_type = PACKET_HOST;
  33         return info->target;
  34 }
  35
  36 static int ebt_redirect_tg_check(const struct xt_tgchk_param *par)
  37 {
  38         const struct ebt_redirect_info *info = par->targinfo;
  39         unsigned int hook_mask;
  40
  41         if (BASE_CHAIN && info->target == EBT_RETURN)
  42                 return -EINVAL;
  43
  44         hook_mask = par->hook_mask & ~(1 << NF_BR_NUMHOOKS);
  45         if ((strcmp(par->table, "nat") != 0 ||
  46             hook_mask & ~(1 << NF_BR_PRE_ROUTING)) &&
  47             (strcmp(par->table, "broute") != 0 ||
  48             hook_mask & ~(1 << NF_BR_BROUTING)))
  49                 return -EINVAL;
  50         if (INVALID_TARGET)
  51                 return -EINVAL;
  52         return 0;
  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     = 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");