net/netfilter/xt_NOTRACK.c

   1 /* This is a module which is used for setting up fake conntracks
   2  * on packets so that they are not seen by the conntrack/NAT code.
   3  */
   4 #include <linux/module.h>
   5 #include <linux/skbuff.h>
   6
   7 #include <linux/netfilter/x_tables.h>
   8 #include <net/netfilter/nf_conntrack_compat.h>
   9
  10 MODULE_LICENSE("GPL");
  11 MODULE_ALIAS("ipt_NOTRACK");
  12
  13 static unsigned int
  14 target(struct sk_buff **pskb,
  15        const struct net_device *in,
  16        const struct net_device *out,
  17        unsigned int hooknum,
  18        const struct xt_target *target,
  19        const void *targinfo,
  20        void *userinfo)
  21 {
  22         /* Previously seen (loopback)? Ignore. */
  23         if ((*pskb)->nfct != NULL)
  24                 return XT_CONTINUE;
  25
  26         /* Attach fake conntrack entry.
  27            If there is a real ct entry correspondig to this packet,
  28            it'll hang aroun till timing out. We don't deal with it
  29            for performance reasons. JK */
  30         nf_ct_untrack(*pskb);
  31         (*pskb)->nfctinfo = IP_CT_NEW;
  32         nf_conntrack_get((*pskb)->nfct);
  33
  34         return XT_CONTINUE;
  35 }
  36
  37 static struct xt_target notrack_reg = {
  38         .name           = "NOTRACK",
  39         .target         = target,
  40         .targetsize     = 0,
  41         .table          = "raw",
  42         .family         = AF_INET,
  43         .me             = THIS_MODULE,
  44 };
  45
  46 static struct xt_target notrack6_reg = {
  47         .name           = "NOTRACK",
  48         .target         = target,
  49         .targetsize     = 0,
  50         .table          = "raw",
  51         .family         = AF_INET6,
  52         .me             = THIS_MODULE,
  53 };
  54
  55 static int __init xt_notrack_init(void)
  56 {
  57         int ret;
  58
  59         ret = xt_register_target(&notrack_reg);
  60         if (ret)
  61                 return ret;
  62
  63         ret = xt_register_target(&notrack6_reg);
  64         if (ret)
  65                 xt_unregister_target(&notrack_reg);
  66
  67         return ret;
  68 }
  69
  70 static void __exit xt_notrack_fini(void)
  71 {
  72         xt_unregister_target(&notrack6_reg);
  73         xt_unregister_target(&notrack_reg);
  74 }
  75
  76 module_init(xt_notrack_init);
  77 module_exit(xt_notrack_fini);