| 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_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 | |
| 42 | static 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 | |
| 53 | static void state_mt_destroy(const struct xt_mtdtor_param *par) |
| 54 | { |
| 55 | nf_ct_l3proto_module_put(par->family); |
| 56 | } |
| 57 | |
| 58 | static 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 | |
| 68 | static int __init state_mt_init(void) |
| 69 | { |
| 70 | return xt_register_match(&state_mt_reg); |
| 71 | } |
| 72 | |
| 73 | static void __exit state_mt_exit(void) |
| 74 | { |
| 75 | xt_unregister_match(&state_mt_reg); |
| 76 | } |
| 77 | |
| 78 | module_init(state_mt_init); |
| 79 | module_exit(state_mt_exit); |