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 struct nf_conn *ct = nf_ct_get(skb, &ctinfo); 30 31 if (ct) 32 statebit = XT_STATE_BIT(ctinfo); 33 else if (ctinfo == IP_CT_UNTRACKED) 34 statebit = XT_STATE_UNTRACKED; 35 else 36 statebit = XT_STATE_INVALID; 37 38 return (sinfo->statemask & statebit); 39 } 40 41 static int state_mt_check(const struct xt_mtchk_param *par) 42 { 43 int ret; 44 45 ret = nf_ct_netns_get(par->net, par->family); 46 if (ret < 0) 47 pr_info_ratelimited("cannot load conntrack support for proto=%u\n", 48 par->family); 49 return ret; 50 } 51 52 static void state_mt_destroy(const struct xt_mtdtor_param *par) 53 { 54 nf_ct_netns_put(par->net, par->family); 55 } 56 57 static struct xt_match state_mt_reg __read_mostly = { 58 .name = "state", 59 .family = NFPROTO_UNSPEC, 60 .checkentry = state_mt_check, 61 .match = state_mt, 62 .destroy = state_mt_destroy, 63 .matchsize = sizeof(struct xt_state_info), 64 .me = THIS_MODULE, 65 }; 66 67 static int __init state_mt_init(void) 68 { 69 return xt_register_match(&state_mt_reg); 70 } 71 72 static void __exit state_mt_exit(void) 73 { 74 xt_unregister_match(&state_mt_reg); 75 } 76 77 module_init(state_mt_init); 78 module_exit(state_mt_exit); 79