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_DESCRIPTION("Xtables: Disabling connection tracking for packets");
  11 MODULE_LICENSE("GPL");
  12 MODULE_ALIAS("ipt_NOTRACK");
  13 MODULE_ALIAS("ip6t_NOTRACK");
  14
  15 static unsigned int
  16 notrack_tg(struct sk_buff *skb, const struct xt_action_param *par)
  17 {
  18         /* Previously seen (loopback)? Ignore. */
  19         if (skb->nfct != NULL)
  20                 return XT_CONTINUE;
  21
  22         /* Attach fake conntrack entry.
  23            If there is a real ct entry correspondig to this packet,
  24            it'll hang aroun till timing out. We don't deal with it
  25            for performance reasons. JK */
  26         skb->nfct = &nf_conntrack_untracked.ct_general;
  27         skb->nfctinfo = IP_CT_NEW;
  28         nf_conntrack_get(skb->nfct);
  29
  30         return XT_CONTINUE;
  31 }
  32
  33 static struct xt_target notrack_tg_reg __read_mostly = {
  34         .name     = "NOTRACK",
  35         .revision = 0,
  36         .family   = NFPROTO_UNSPEC,
  37         .target   = notrack_tg,
  38         .table    = "raw",
  39         .me       = THIS_MODULE,
  40 };
  41
  42 static int __init notrack_tg_init(void)
  43 {
  44         return xt_register_target(&notrack_tg_reg);
  45 }
  46
  47 static void __exit notrack_tg_exit(void)
  48 {
  49         xt_unregister_target(&notrack_tg_reg);
  50 }
  51
  52 module_init(notrack_tg_init);
  53 module_exit(notrack_tg_exit);