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, struct xt_action_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 int state_mt_check(const struct xt_mtchk_param *par) 41 { 42 int ret; 43 44 ret = nf_ct_l3proto_try_module_get(par->family); 45 if (ret < 0) 46 pr_info("cannot load conntrack support for proto=%u\n", 47 par->family); 48 return ret; 49 } 50 51 static void state_mt_destroy(const struct xt_mtdtor_param *par) 52 { 53 nf_ct_l3proto_module_put(par->family); 54 } 55 56 static struct xt_match state_mt_reg __read_mostly = { 57 .name = "state", 58 .family = NFPROTO_UNSPEC, 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 static int __init state_mt_init(void) 67 { 68 return xt_register_match(&state_mt_reg); 69 } 70 71 static void __exit state_mt_exit(void) 72 { 73 xt_unregister_match(&state_mt_reg); 74 } 75 76 module_init(state_mt_init); 77 module_exit(state_mt_exit); 78