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1// SPDX-License-Identifier: GPL-2.0-only
2/* iptables module to match on related connections */
3/*
4 * (C) 2001 Martin Josefsson <gandalf@wlug.westbo.se>
5 */
6#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
7#include <linux/module.h>
8#include <linux/skbuff.h>
9#include <linux/netfilter.h>
10#include <net/netfilter/nf_conntrack.h>
11#include <net/netfilter/nf_conntrack_core.h>
12#include <net/netfilter/nf_conntrack_helper.h>
13#include <linux/netfilter/x_tables.h>
14#include <linux/netfilter/xt_helper.h>
15
16MODULE_LICENSE("GPL");
17MODULE_AUTHOR("Martin Josefsson <gandalf@netfilter.org>");
18MODULE_DESCRIPTION("Xtables: Related connection matching");
19MODULE_ALIAS("ipt_helper");
20MODULE_ALIAS("ip6t_helper");
21
22
23static bool
24helper_mt(const struct sk_buff *skb, struct xt_action_param *par)
25{
26 const struct xt_helper_info *info = par->matchinfo;
27 const struct nf_conn *ct;
28 const struct nf_conn_help *master_help;
29 const struct nf_conntrack_helper *helper;
30 enum ip_conntrack_info ctinfo;
31 bool ret = info->invert;
32
33 ct = nf_ct_get(skb, &ctinfo);
34 if (!ct || !ct->master)
35 return ret;
36
37 master_help = nfct_help(ct->master);
38 if (!master_help)
39 return ret;
40
41 /* rcu_read_lock()ed by nf_hook_thresh */
42 helper = rcu_dereference(master_help->helper);
43 if (!helper)
44 return ret;
45
46 if (info->name[0] == '\0')
47 ret = !ret;
48 else
49 ret ^= !strncmp(helper->name, info->name,
50 strlen(helper->name));
51 return ret;
52}
53
54static int helper_mt_check(const struct xt_mtchk_param *par)
55{
56 struct xt_helper_info *info = par->matchinfo;
57 int ret;
58
59 ret = nf_ct_netns_get(par->net, par->family);
60 if (ret < 0) {
61 pr_info_ratelimited("cannot load conntrack support for proto=%u\n",
62 par->family);
63 return ret;
64 }
65 info->name[sizeof(info->name) - 1] = '\0';
66 return 0;
67}
68
69static void helper_mt_destroy(const struct xt_mtdtor_param *par)
70{
71 nf_ct_netns_put(par->net, par->family);
72}
73
74static struct xt_match helper_mt_reg __read_mostly = {
75 .name = "helper",
76 .revision = 0,
77 .family = NFPROTO_UNSPEC,
78 .checkentry = helper_mt_check,
79 .match = helper_mt,
80 .destroy = helper_mt_destroy,
81 .matchsize = sizeof(struct xt_helper_info),
82 .me = THIS_MODULE,
83};
84
85static int __init helper_mt_init(void)
86{
87 return xt_register_match(&helper_mt_reg);
88}
89
90static void __exit helper_mt_exit(void)
91{
92 xt_unregister_match(&helper_mt_reg);
93}
94
95module_init(helper_mt_init);
96module_exit(helper_mt_exit);
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
19MODULE_LICENSE("GPL");
20MODULE_AUTHOR("Martin Josefsson <gandalf@netfilter.org>");
21MODULE_DESCRIPTION("Xtables: Related connection matching");
22MODULE_ALIAS("ipt_helper");
23MODULE_ALIAS("ip6t_helper");
24
25
26static bool
27helper_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
57static 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
72static void helper_mt_destroy(const struct xt_mtdtor_param *par)
73{
74 nf_ct_l3proto_module_put(par->family);
75}
76
77static 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
88static int __init helper_mt_init(void)
89{
90 return xt_register_match(&helper_mt_reg);
91}
92
93static void __exit helper_mt_exit(void)
94{
95 xt_unregister_match(&helper_mt_reg);
96}
97
98module_init(helper_mt_init);
99module_exit(helper_mt_exit);