1 /*
2  * This module is used to copy security markings from packets
3  * to connections, and restore security markings from connections
4  * back to packets.  This would normally be performed in conjunction
5  * with the SECMARK target and state match.
6  *
7  * Based somewhat on CONNMARK:
8  *   Copyright (C) 2002,2004 MARA Systems AB <http://www.marasystems.com>
9  *    by Henrik Nordstrom <hno@marasystems.com>
10  *
11  * (C) 2006,2008 Red Hat, Inc., James Morris <jmorris@redhat.com>
12  *
13  * This program is free software; you can redistribute it and/or modify
14  * it under the terms of the GNU General Public License version 2 as
15  * published by the Free Software Foundation.
16  *
17  */
18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
19 #include <linux/module.h>
20 #include <linux/skbuff.h>
21 #include <linux/netfilter/x_tables.h>
22 #include <linux/netfilter/xt_CONNSECMARK.h>
23 #include <net/netfilter/nf_conntrack.h>
24 #include <net/netfilter/nf_conntrack_ecache.h>
25 
26 MODULE_LICENSE("GPL");
27 MODULE_AUTHOR("James Morris <jmorris@redhat.com>");
28 MODULE_DESCRIPTION("Xtables: target for copying between connection and security mark");
29 MODULE_ALIAS("ipt_CONNSECMARK");
30 MODULE_ALIAS("ip6t_CONNSECMARK");
31 
32 /*
33  * If the packet has a security mark and the connection does not, copy
34  * the security mark from the packet to the connection.
35  */
36 static void secmark_save(const struct sk_buff *skb)
37 {
38 	if (skb->secmark) {
39 		struct nf_conn *ct;
40 		enum ip_conntrack_info ctinfo;
41 
42 		ct = nf_ct_get(skb, &ctinfo);
43 		if (ct && !ct->secmark) {
44 			ct->secmark = skb->secmark;
45 			nf_conntrack_event_cache(IPCT_SECMARK, ct);
46 		}
47 	}
48 }
49 
50 /*
51  * If packet has no security mark, and the connection does, restore the
52  * security mark from the connection to the packet.
53  */
54 static void secmark_restore(struct sk_buff *skb)
55 {
56 	if (!skb->secmark) {
57 		const struct nf_conn *ct;
58 		enum ip_conntrack_info ctinfo;
59 
60 		ct = nf_ct_get(skb, &ctinfo);
61 		if (ct && ct->secmark)
62 			skb->secmark = ct->secmark;
63 	}
64 }
65 
66 static unsigned int
67 connsecmark_tg(struct sk_buff *skb, const struct xt_action_param *par)
68 {
69 	const struct xt_connsecmark_target_info *info = par->targinfo;
70 
71 	switch (info->mode) {
72 	case CONNSECMARK_SAVE:
73 		secmark_save(skb);
74 		break;
75 
76 	case CONNSECMARK_RESTORE:
77 		secmark_restore(skb);
78 		break;
79 
80 	default:
81 		BUG();
82 	}
83 
84 	return XT_CONTINUE;
85 }
86 
87 static int connsecmark_tg_check(const struct xt_tgchk_param *par)
88 {
89 	const struct xt_connsecmark_target_info *info = par->targinfo;
90 	int ret;
91 
92 	if (strcmp(par->table, "mangle") != 0 &&
93 	    strcmp(par->table, "security") != 0) {
94 		pr_info("target only valid in the \'mangle\' "
95 			"or \'security\' tables, not \'%s\'.\n", par->table);
96 		return -EINVAL;
97 	}
98 
99 	switch (info->mode) {
100 	case CONNSECMARK_SAVE:
101 	case CONNSECMARK_RESTORE:
102 		break;
103 
104 	default:
105 		pr_info("invalid mode: %hu\n", info->mode);
106 		return -EINVAL;
107 	}
108 
109 	ret = nf_ct_l3proto_try_module_get(par->family);
110 	if (ret < 0)
111 		pr_info("cannot load conntrack support for proto=%u\n",
112 			par->family);
113 	return ret;
114 }
115 
116 static void connsecmark_tg_destroy(const struct xt_tgdtor_param *par)
117 {
118 	nf_ct_l3proto_module_put(par->family);
119 }
120 
121 static struct xt_target connsecmark_tg_reg __read_mostly = {
122 	.name       = "CONNSECMARK",
123 	.revision   = 0,
124 	.family     = NFPROTO_UNSPEC,
125 	.checkentry = connsecmark_tg_check,
126 	.destroy    = connsecmark_tg_destroy,
127 	.target     = connsecmark_tg,
128 	.targetsize = sizeof(struct xt_connsecmark_target_info),
129 	.me         = THIS_MODULE,
130 };
131 
132 static int __init connsecmark_tg_init(void)
133 {
134 	return xt_register_target(&connsecmark_tg_reg);
135 }
136 
137 static void __exit connsecmark_tg_exit(void)
138 {
139 	xt_unregister_target(&connsecmark_tg_reg);
140 }
141 
142 module_init(connsecmark_tg_init);
143 module_exit(connsecmark_tg_exit);
144