1 // SPDX-License-Identifier: GPL-2.0-only 2 /* Kernel module to match connection tracking information. */ 3 4 /* (C) 1999-2001 Paul `Rusty' Russell 5 * (C) 2002-2005 Netfilter Core Team <coreteam@netfilter.org> 6 */ 7 8 #include <linux/module.h> 9 #include <linux/skbuff.h> 10 #include <net/netfilter/nf_conntrack.h> 11 #include <linux/netfilter/x_tables.h> 12 #include <linux/netfilter/xt_state.h> 13 14 MODULE_LICENSE("GPL"); 15 MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>"); 16 MODULE_DESCRIPTION("ip[6]_tables connection tracking state match module"); 17 MODULE_ALIAS("ipt_state"); 18 MODULE_ALIAS("ip6t_state"); 19 20 static bool 21 state_mt(const struct sk_buff *skb, struct xt_action_param *par) 22 { 23 const struct xt_state_info *sinfo = par->matchinfo; 24 enum ip_conntrack_info ctinfo; 25 unsigned int statebit; 26 struct nf_conn *ct = nf_ct_get(skb, &ctinfo); 27 28 if (ct) 29 statebit = XT_STATE_BIT(ctinfo); 30 else if (ctinfo == IP_CT_UNTRACKED) 31 statebit = XT_STATE_UNTRACKED; 32 else 33 statebit = XT_STATE_INVALID; 34 35 return (sinfo->statemask & statebit); 36 } 37 38 static int state_mt_check(const struct xt_mtchk_param *par) 39 { 40 int ret; 41 42 ret = nf_ct_netns_get(par->net, par->family); 43 if (ret < 0) 44 pr_info_ratelimited("cannot load conntrack support for proto=%u\n", 45 par->family); 46 return ret; 47 } 48 49 static void state_mt_destroy(const struct xt_mtdtor_param *par) 50 { 51 nf_ct_netns_put(par->net, par->family); 52 } 53 54 static struct xt_match state_mt_reg __read_mostly = { 55 .name = "state", 56 .family = NFPROTO_UNSPEC, 57 .checkentry = state_mt_check, 58 .match = state_mt, 59 .destroy = state_mt_destroy, 60 .matchsize = sizeof(struct xt_state_info), 61 .me = THIS_MODULE, 62 }; 63 64 static int __init state_mt_init(void) 65 { 66 return xt_register_match(&state_mt_reg); 67 } 68 69 static void __exit state_mt_exit(void) 70 { 71 xt_unregister_match(&state_mt_reg); 72 } 73 74 module_init(state_mt_init); 75 module_exit(state_mt_exit); 76