net/netfilter/xt_state.c

   1 /* Kernel module to match connection tracking information. */
   2
   3 /* (C) 1999-2001 Paul `Rusty' Russell
   4  * (C) 2002-2005 Netfilter Core Team <coreteam@netfilter.org>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/skbuff.h>
  13 #include <net/netfilter/nf_conntrack_compat.h>
  14 #include <linux/netfilter/x_tables.h>
  15 #include <linux/netfilter/xt_state.h>
  16
  17 MODULE_LICENSE("GPL");
  18 MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
  19 MODULE_DESCRIPTION("ip[6]_tables connection tracking state match module");
  20 MODULE_ALIAS("ipt_state");
  21 MODULE_ALIAS("ip6t_state");
  22
  23 static int
  24 match(const struct sk_buff *skb,
  25       const struct net_device *in,
  26       const struct net_device *out,
  27       const struct xt_match *match,
  28       const void *matchinfo,
  29       int offset,
  30       unsigned int protoff,
  31       int *hotdrop)
  32 {
  33         const struct xt_state_info *sinfo = matchinfo;
  34         enum ip_conntrack_info ctinfo;
  35         unsigned int statebit;
  36
  37         if (nf_ct_is_untracked(skb))
  38                 statebit = XT_STATE_UNTRACKED;
  39         else if (!nf_ct_get_ctinfo(skb, &ctinfo))
  40                 statebit = XT_STATE_INVALID;
  41         else
  42                 statebit = XT_STATE_BIT(ctinfo);
  43
  44         return (sinfo->statemask & statebit);
  45 }
  46
  47 static struct xt_match state_match = {
  48         .name           = "state",
  49         .match          = match,
  50         .matchsize      = sizeof(struct xt_state_info),
  51         .me             = THIS_MODULE,
  52 };
  53
  54 static struct xt_match state6_match = {
  55         .name           = "state",
  56         .match          = match,
  57         .matchsize      = sizeof(struct xt_state_info),
  58         .me             = THIS_MODULE,
  59 };
  60
  61 static int __init init(void)
  62 {
  63         int ret;
  64
  65         need_conntrack();
  66
  67         ret = xt_register_match(AF_INET, &state_match);
  68         if (ret < 0)
  69                 return ret;
  70
  71         ret = xt_register_match(AF_INET6, &state6_match);
  72         if (ret < 0)
  73                 xt_unregister_match(AF_INET,&state_match);
  74
  75         return ret;
  76 }
  77
  78 static void __exit fini(void)
  79 {
  80         xt_unregister_match(AF_INET, &state_match);
  81         xt_unregister_match(AF_INET6, &state6_match);
  82 }
  83
  84 module_init(init);
  85 module_exit(fini);