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 17MODULE_LICENSE("GPL"); 18MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>"); 19MODULE_DESCRIPTION("ip[6]_tables connection tracking state match module"); 20MODULE_ALIAS("ipt_state"); 21MODULE_ALIAS("ip6t_state"); 22 23static bool 24state_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_INVALID; 33 else { 34 if (nf_ct_is_untracked(ct)) 35 statebit = XT_STATE_UNTRACKED; 36 else 37 statebit = XT_STATE_BIT(ctinfo); 38 } 39 return (sinfo->statemask & statebit); 40} 41 42static int state_mt_check(const struct xt_mtchk_param *par) 43{ 44 int ret; 45 46 ret = nf_ct_l3proto_try_module_get(par->family); 47 if (ret < 0) 48 pr_info("cannot load conntrack support for proto=%u\n", 49 par->family); 50 return ret; 51} 52 53static void state_mt_destroy(const struct xt_mtdtor_param *par) 54{ 55 nf_ct_l3proto_module_put(par->family); 56} 57 58static struct xt_match state_mt_reg __read_mostly = { 59 .name = "state", 60 .family = NFPROTO_UNSPEC, 61 .checkentry = state_mt_check, 62 .match = state_mt, 63 .destroy = state_mt_destroy, 64 .matchsize = sizeof(struct xt_state_info), 65 .me = THIS_MODULE, 66}; 67 68static int __init state_mt_init(void) 69{ 70 return xt_register_match(&state_mt_reg); 71} 72 73static void __exit state_mt_exit(void) 74{ 75 xt_unregister_match(&state_mt_reg); 76} 77 78module_init(state_mt_init); 79module_exit(state_mt_exit); 80