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
  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 {
  21         /* Previously seen (loopback)? Ignore. */
  22         if ((*pskb)->nfct != NULL)
  23                 return XT_CONTINUE;
  24
  25         /* Attach fake conntrack entry.
  26            If there is a real ct entry correspondig to this packet,
  27            it'll hang aroun till timing out. We don't deal with it
  28            for performance reasons. JK */
  29         (*pskb)->nfct = &nf_conntrack_untracked.ct_general;
  30         (*pskb)->nfctinfo = IP_CT_NEW;
  31         nf_conntrack_get((*pskb)->nfct);
  32
  33         return XT_CONTINUE;
  34 }
  35
  36 static struct xt_target xt_notrack_target[] __read_mostly = {
  37         {
  38                 .name           = "NOTRACK",
  39                 .family         = AF_INET,
  40                 .target         = target,
  41                 .table          = "raw",
  42                 .me             = THIS_MODULE,
  43         },
  44         {
  45                 .name           = "NOTRACK",
  46                 .family         = AF_INET6,
  47                 .target         = target,
  48                 .table          = "raw",
  49                 .me             = THIS_MODULE,
  50         },
  51 };
  52
  53 static int __init xt_notrack_init(void)
  54 {
  55         return xt_register_targets(xt_notrack_target,
  56                                    ARRAY_SIZE(xt_notrack_target));
  57 }
  58
  59 static void __exit xt_notrack_fini(void)
  60 {
  61         xt_unregister_targets(xt_notrack_target, ARRAY_SIZE(xt_notrack_target));
  62 }
  63
  64 module_init(xt_notrack_init);
  65 module_exit(xt_notrack_fini);