1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * This module is used to copy security markings from packets
4 * to connections, and restore security markings from connections
5 * back to packets.  This would normally be performed in conjunction
6 * with the SECMARK target and state match.
7 *
8 * Based somewhat on CONNMARK:
9 *   Copyright (C) 2002,2004 MARA Systems AB <https://www.marasystems.com>
10 *    by Henrik Nordstrom <hno@marasystems.com>
11 *
12 * (C) 2006,2008 Red Hat, Inc., James Morris <jmorris@redhat.com>
13 */
14#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15#include <linux/module.h>
16#include <linux/skbuff.h>
17#include <linux/netfilter/x_tables.h>
18#include <linux/netfilter/xt_CONNSECMARK.h>
19#include <net/netfilter/nf_conntrack.h>
20#include <net/netfilter/nf_conntrack_ecache.h>
21
22MODULE_LICENSE("GPL");
23MODULE_AUTHOR("James Morris <jmorris@redhat.com>");
24MODULE_DESCRIPTION("Xtables: target for copying between connection and security mark");
25MODULE_ALIAS("ipt_CONNSECMARK");
26MODULE_ALIAS("ip6t_CONNSECMARK");
27
28/*
29 * If the packet has a security mark and the connection does not, copy
30 * the security mark from the packet to the connection.
31 */
32static void secmark_save(const struct sk_buff *skb)
33{
34	if (skb->secmark) {
35		struct nf_conn *ct;
36		enum ip_conntrack_info ctinfo;
37
38		ct = nf_ct_get(skb, &ctinfo);
39		if (ct && !ct->secmark) {
40			ct->secmark = skb->secmark;
41			nf_conntrack_event_cache(IPCT_SECMARK, ct);
42		}
43	}
44}
45
46/*
47 * If packet has no security mark, and the connection does, restore the
48 * security mark from the connection to the packet.
49 */
50static void secmark_restore(struct sk_buff *skb)
51{
52	if (!skb->secmark) {
53		const struct nf_conn *ct;
54		enum ip_conntrack_info ctinfo;
55
56		ct = nf_ct_get(skb, &ctinfo);
57		if (ct && ct->secmark)
58			skb->secmark = ct->secmark;
59	}
60}
61
62static unsigned int
63connsecmark_tg(struct sk_buff *skb, const struct xt_action_param *par)
64{
65	const struct xt_connsecmark_target_info *info = par->targinfo;
66
67	switch (info->mode) {
68	case CONNSECMARK_SAVE:
69		secmark_save(skb);
70		break;
71
72	case CONNSECMARK_RESTORE:
73		secmark_restore(skb);
74		break;
75
76	default:
77		BUG();
78	}
79
80	return XT_CONTINUE;
81}
82
83static int connsecmark_tg_check(const struct xt_tgchk_param *par)
84{
85	const struct xt_connsecmark_target_info *info = par->targinfo;
86	int ret;
87
88	if (strcmp(par->table, "mangle") != 0 &&
89	    strcmp(par->table, "security") != 0) {
90		pr_info_ratelimited("only valid in \'mangle\' or \'security\' table, not \'%s\'\n",
91				    par->table);
92		return -EINVAL;
93	}
94
95	switch (info->mode) {
96	case CONNSECMARK_SAVE:
97	case CONNSECMARK_RESTORE:
98		break;
99
100	default:
101		pr_info_ratelimited("invalid mode: %hu\n", info->mode);
102		return -EINVAL;
103	}
104
105	ret = nf_ct_netns_get(par->net, par->family);
106	if (ret < 0)
107		pr_info_ratelimited("cannot load conntrack support for proto=%u\n",
108				    par->family);
109	return ret;
110}
111
112static void connsecmark_tg_destroy(const struct xt_tgdtor_param *par)
113{
114	nf_ct_netns_put(par->net, par->family);
115}
116
117static struct xt_target connsecmark_tg_reg __read_mostly = {
118	.name       = "CONNSECMARK",
119	.revision   = 0,
120	.family     = NFPROTO_UNSPEC,
121	.checkentry = connsecmark_tg_check,
122	.destroy    = connsecmark_tg_destroy,
123	.target     = connsecmark_tg,
124	.targetsize = sizeof(struct xt_connsecmark_target_info),
125	.me         = THIS_MODULE,
126};
127
128static int __init connsecmark_tg_init(void)
129{
130	return xt_register_target(&connsecmark_tg_reg);
131}
132
133static void __exit connsecmark_tg_exit(void)
134{
135	xt_unregister_target(&connsecmark_tg_reg);
136}
137
138module_init(connsecmark_tg_init);
139module_exit(connsecmark_tg_exit);
140