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 void *targinfo,
  19        void *userinfo)
  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         nf_ct_untrack(*pskb);
  30         (*pskb)->nfctinfo = IP_CT_NEW;
  31         nf_conntrack_get((*pskb)->nfct);
  32
  33         return XT_CONTINUE;
  34 }
  35
  36 static int
  37 checkentry(const char *tablename,
  38            const void *entry,
  39            void *targinfo,
  40            unsigned int targinfosize,
  41            unsigned int hook_mask)
  42 {
  43         if (targinfosize != 0) {
  44                 printk(KERN_WARNING "NOTRACK: targinfosize %u != 0\n",
  45                        targinfosize);
  46                 return 0;
  47         }
  48
  49         if (strcmp(tablename, "raw") != 0) {
  50                 printk(KERN_WARNING "NOTRACK: can only be called from \"raw\" table, not \"%s\"\n", tablename);
  51                 return 0;
  52         }
  53
  54         return 1;
  55 }
  56
  57 static struct xt_target notrack_reg = {
  58         .name = "NOTRACK",
  59         .target = target,
  60         .checkentry = checkentry,
  61         .me = THIS_MODULE,
  62 };
  63 static struct xt_target notrack6_reg = {
  64         .name = "NOTRACK",
  65         .target = target,
  66         .checkentry = checkentry,
  67         .me = THIS_MODULE,
  68 };
  69
  70 static int __init init(void)
  71 {
  72         int ret;
  73
  74         ret = xt_register_target(AF_INET, &notrack_reg);
  75         if (ret)
  76                 return ret;
  77
  78         ret = xt_register_target(AF_INET6, &notrack6_reg);
  79         if (ret)
  80                 xt_unregister_target(AF_INET, &notrack_reg);
  81
  82         return ret;
  83 }
  84
  85 static void __exit fini(void)
  86 {
  87         xt_unregister_target(AF_INET6, &notrack6_reg);
  88         xt_unregister_target(AF_INET, &notrack_reg);
  89 }
  90
  91 module_init(init);
  92 module_exit(fini);