| /* iptables module to match on related connections */ |
| /* |
| * (C) 2001 Martin Josefsson <gandalf@wlug.westbo.se> |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. |
| */ |
| #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| #include <linux/module.h> |
| #include <linux/skbuff.h> |
| #include <linux/netfilter.h> |
| #include <net/netfilter/nf_conntrack.h> |
| #include <net/netfilter/nf_conntrack_core.h> |
| #include <net/netfilter/nf_conntrack_helper.h> |
| #include <linux/netfilter/x_tables.h> |
| #include <linux/netfilter/xt_helper.h> |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_AUTHOR("Martin Josefsson <gandalf@netfilter.org>"); |
| MODULE_DESCRIPTION("Xtables: Related connection matching"); |
| MODULE_ALIAS("ipt_helper"); |
| MODULE_ALIAS("ip6t_helper"); |
| |
| |
| static bool |
| helper_mt(const struct sk_buff *skb, const struct xt_match_param *par) |
| { |
| const struct xt_helper_info *info = par->matchinfo; |
| const struct nf_conn *ct; |
| const struct nf_conn_help *master_help; |
| const struct nf_conntrack_helper *helper; |
| enum ip_conntrack_info ctinfo; |
| bool ret = info->invert; |
| |
| ct = nf_ct_get(skb, &ctinfo); |
| if (!ct || !ct->master) |
| return ret; |
| |
| master_help = nfct_help(ct->master); |
| if (!master_help) |
| return ret; |
| |
| /* rcu_read_lock()ed by nf_hook_slow */ |
| helper = rcu_dereference(master_help->helper); |
| if (!helper) |
| return ret; |
| |
| if (info->name[0] == '\0') |
| ret = !ret; |
| else |
| ret ^= !strncmp(helper->name, info->name, |
| strlen(helper->name)); |
| return ret; |
| } |
| |
| static int helper_mt_check(const struct xt_mtchk_param *par) |
| { |
| struct xt_helper_info *info = par->matchinfo; |
| |
| if (nf_ct_l3proto_try_module_get(par->family) < 0) { |
| pr_info("cannot load conntrack support for proto=%u\n", |
| par->family); |
| return -EINVAL; |
| } |
| info->name[29] = '\0'; |
| return 0; |
| } |
| |
| static void helper_mt_destroy(const struct xt_mtdtor_param *par) |
| { |
| nf_ct_l3proto_module_put(par->family); |
| } |
| |
| static struct xt_match helper_mt_reg __read_mostly = { |
| .name = "helper", |
| .revision = 0, |
| .family = NFPROTO_UNSPEC, |
| .checkentry = helper_mt_check, |
| .match = helper_mt, |
| .destroy = helper_mt_destroy, |
| .matchsize = sizeof(struct xt_helper_info), |
| .me = THIS_MODULE, |
| }; |
| |
| static int __init helper_mt_init(void) |
| { |
| return xt_register_match(&helper_mt_reg); |
| } |
| |
| static void __exit helper_mt_exit(void) |
| { |
| xt_unregister_match(&helper_mt_reg); |
| } |
| |
| module_init(helper_mt_init); |
| module_exit(helper_mt_exit); |