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.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 bool
  24 state_mt(const struct sk_buff *skb, const struct xt_match_param *par)
  25 {
  26         const struct xt_state_info *sinfo = par->matchinfo;
  27         enum ip_conntrack_info ctinfo;
  28         unsigned int statebit;
  29
  30         if (nf_ct_is_untracked(skb))
  31                 statebit = XT_STATE_UNTRACKED;
  32         else if (!nf_ct_get(skb, &ctinfo))
  33                 statebit = XT_STATE_INVALID;
  34         else
  35                 statebit = XT_STATE_BIT(ctinfo);
  36
  37         return (sinfo->statemask & statebit);
  38 }
  39
  40 static bool state_mt_check(const struct xt_mtchk_param *par)
  41 {
  42         if (nf_ct_l3proto_try_module_get(par->match->family) < 0) {
  43                 printk(KERN_WARNING "can't load conntrack support for "
  44                                     "proto=%u\n", par->match->family);
  45                 return false;
  46         }
  47         return true;
  48 }
  49
  50 static void state_mt_destroy(const struct xt_mtdtor_param *par)
  51 {
  52         nf_ct_l3proto_module_put(par->match->family);
  53 }
  54
  55 static struct xt_match state_mt_reg[] __read_mostly = {
  56         {
  57                 .name           = "state",
  58                 .family         = NFPROTO_IPV4,
  59                 .checkentry     = state_mt_check,
  60                 .match          = state_mt,
  61                 .destroy        = state_mt_destroy,
  62                 .matchsize      = sizeof(struct xt_state_info),
  63                 .me             = THIS_MODULE,
  64         },
  65         {
  66                 .name           = "state",
  67                 .family         = NFPROTO_IPV6,
  68                 .checkentry     = state_mt_check,
  69                 .match          = state_mt,
  70                 .destroy        = state_mt_destroy,
  71                 .matchsize      = sizeof(struct xt_state_info),
  72                 .me             = THIS_MODULE,
  73         },
  74 };
  75
  76 static int __init state_mt_init(void)
  77 {
  78         return xt_register_matches(state_mt_reg, ARRAY_SIZE(state_mt_reg));
  79 }
  80
  81 static void __exit state_mt_exit(void)
  82 {
  83         xt_unregister_matches(state_mt_reg, ARRAY_SIZE(state_mt_reg));
  84 }
  85
  86 module_init(state_mt_init);
  87 module_exit(state_mt_exit);