| | 1 | /* iptables module to match on related connections */ |
| | 2 | /* |
| | 3 | * (C) 2001 Martin Josefsson <gandalf@wlug.westbo.se> |
| | 4 | * |
| | 5 | * This program is free software; you can redistribute it and/or modify |
| | 6 | * it under the terms of the GNU General Public License version 2 as |
| | 7 | * published by the Free Software Foundation. |
| | 8 | */ |
| | 9 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| | 10 | #include <linux/module.h> |
| | 11 | #include <linux/skbuff.h> |
| | 12 | #include <linux/netfilter.h> |
| | 13 | #include <net/netfilter/nf_conntrack.h> |
| | 14 | #include <net/netfilter/nf_conntrack_core.h> |
| | 15 | #include <net/netfilter/nf_conntrack_helper.h> |
| | 16 | #include <linux/netfilter/x_tables.h> |
| | 17 | #include <linux/netfilter/xt_helper.h> |
| | 18 | |
| | 19 | MODULE_LICENSE("GPL"); |
| | 20 | MODULE_AUTHOR("Martin Josefsson <gandalf@netfilter.org>"); |
| | 21 | MODULE_DESCRIPTION("Xtables: Related connection matching"); |
| | 22 | MODULE_ALIAS("ipt_helper"); |
| | 23 | MODULE_ALIAS("ip6t_helper"); |
| | 24 | |
| | 25 | |
| | 26 | static bool |
| | 27 | helper_mt(const struct sk_buff *skb, struct xt_action_param *par) |
| | 28 | { |
| | 29 | const struct xt_helper_info *info = par->matchinfo; |
| | 30 | const struct nf_conn *ct; |
| | 31 | const struct nf_conn_help *master_help; |
| | 32 | const struct nf_conntrack_helper *helper; |
| | 33 | enum ip_conntrack_info ctinfo; |
| | 34 | bool ret = info->invert; |
| | 35 | |
| | 36 | ct = nf_ct_get(skb, &ctinfo); |
| | 37 | if (!ct || !ct->master) |
| | 38 | return ret; |
| | 39 | |
| | 40 | master_help = nfct_help(ct->master); |
| | 41 | if (!master_help) |
| | 42 | return ret; |
| | 43 | |
| | 44 | /* rcu_read_lock()ed by nf_hook_slow */ |
| | 45 | helper = rcu_dereference(master_help->helper); |
| | 46 | if (!helper) |
| | 47 | return ret; |
| | 48 | |
| | 49 | if (info->name[0] == '\0') |
| | 50 | ret = !ret; |
| | 51 | else |
| | 52 | ret ^= !strncmp(helper->name, info->name, |
| | 53 | strlen(helper->name)); |
| | 54 | return ret; |
| | 55 | } |
| | 56 | |
| | 57 | static int helper_mt_check(const struct xt_mtchk_param *par) |
| | 58 | { |
| | 59 | struct xt_helper_info *info = par->matchinfo; |
| | 60 | int ret; |
| | 61 | |
| | 62 | ret = nf_ct_l3proto_try_module_get(par->family); |
| | 63 | if (ret < 0) { |
| | 64 | pr_info("cannot load conntrack support for proto=%u\n", |
| | 65 | par->family); |
| | 66 | return ret; |
| | 67 | } |
| | 68 | info->name[29] = '\0'; |
| | 69 | return 0; |
| | 70 | } |
| | 71 | |
| | 72 | static void helper_mt_destroy(const struct xt_mtdtor_param *par) |
| | 73 | { |
| | 74 | nf_ct_l3proto_module_put(par->family); |
| | 75 | } |
| | 76 | |
| | 77 | static struct xt_match helper_mt_reg __read_mostly = { |
| | 78 | .name = "helper", |
| | 79 | .revision = 0, |
| | 80 | .family = NFPROTO_UNSPEC, |
| | 81 | .checkentry = helper_mt_check, |
| | 82 | .match = helper_mt, |
| | 83 | .destroy = helper_mt_destroy, |
| | 84 | .matchsize = sizeof(struct xt_helper_info), |
| | 85 | .me = THIS_MODULE, |
| | 86 | }; |
| | 87 | |
| | 88 | static int __init helper_mt_init(void) |
| | 89 | { |
| | 90 | return xt_register_match(&helper_mt_reg); |
| | 91 | } |
| | 92 | |
| | 93 | static void __exit helper_mt_exit(void) |
| | 94 | { |
| | 95 | xt_unregister_match(&helper_mt_reg); |
| | 96 | } |
| | 97 | |
| | 98 | module_init(helper_mt_init); |
| | 99 | module_exit(helper_mt_exit); |
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