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.h>
   9
  10 MODULE_LICENSE("GPL");
  11 MODULE_ALIAS("ipt_NOTRACK");
  12 MODULE_ALIAS("ip6t_NOTRACK");
  13
  14 static unsigned int
  15 target(struct sk_buff *skb,
  16        const struct net_device *in,
  17        const struct net_device *out,
  18        unsigned int hooknum,
  19        const struct xt_target *target,
  20        const void *targinfo)
  21 {
  22         /* Previously seen (loopback)? Ignore. */
  23         if (skb->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         skb->nfct = &nf_conntrack_untracked.ct_general;
  31         skb->nfctinfo = IP_CT_NEW;
  32         nf_conntrack_get(skb->nfct);
  33
  34         return XT_CONTINUE;
  35 }
  36
  37 static struct xt_target xt_notrack_target[] __read_mostly = {
  38         {
  39                 .name           = "NOTRACK",
  40                 .family         = AF_INET,
  41                 .target         = target,
  42                 .table          = "raw",
  43                 .me             = THIS_MODULE,
  44         },
  45         {
  46                 .name           = "NOTRACK",
  47                 .family         = AF_INET6,
  48                 .target         = target,
  49                 .table          = "raw",
  50                 .me             = THIS_MODULE,
  51         },
  52 };
  53
  54 static int __init xt_notrack_init(void)
  55 {
  56         return xt_register_targets(xt_notrack_target,
  57                                    ARRAY_SIZE(xt_notrack_target));
  58 }
  59
  60 static void __exit xt_notrack_fini(void)
  61 {
  62         xt_unregister_targets(xt_notrack_target, ARRAY_SIZE(xt_notrack_target));
  63 }
  64
  65 module_init(xt_notrack_init);
  66 module_exit(xt_notrack_fini);