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 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 #include <linux/module.h>
19 #include <linux/skbuff.h>
20 #include <linux/netfilter/x_tables.h>
21 #include <linux/netfilter/xt_CONNSECMARK.h>
22 #include <net/netfilter/nf_conntrack.h>
23 #include <net/netfilter/nf_conntrack_ecache.h>
24 
25 #define PFX "CONNSECMARK: "
26 
27 MODULE_LICENSE("GPL");
28 MODULE_AUTHOR("James Morris <jmorris@redhat.com>");
29 MODULE_DESCRIPTION("ip[6]tables CONNSECMARK module");
30 MODULE_ALIAS("ipt_CONNSECMARK");
31 MODULE_ALIAS("ip6t_CONNSECMARK");
32 
33 /*
34  * If the packet has a security mark and the connection does not, copy
35  * the security mark from the packet to the connection.
36  */
37 static void secmark_save(const struct sk_buff *skb)
38 {
39 	if (skb->secmark) {
40 		struct nf_conn *ct;
41 		enum ip_conntrack_info ctinfo;
42 
43 		ct = nf_ct_get(skb, &ctinfo);
44 		if (ct && !ct->secmark) {
45 			ct->secmark = skb->secmark;
46 			nf_conntrack_event_cache(IPCT_SECMARK, skb);
47 		}
48 	}
49 }
50 
51 /*
52  * If packet has no security mark, and the connection does, restore the
53  * security mark from the connection to the packet.
54  */
55 static void secmark_restore(struct sk_buff *skb)
56 {
57 	if (!skb->secmark) {
58 		struct nf_conn *ct;
59 		enum ip_conntrack_info ctinfo;
60 
61 		ct = nf_ct_get(skb, &ctinfo);
62 		if (ct && ct->secmark)
63 			skb->secmark = ct->secmark;
64 	}
65 }
66 
67 static unsigned int
68 connsecmark_tg(struct sk_buff *skb, const struct net_device *in,
69                const struct net_device *out, unsigned int hooknum,
70                const struct xt_target *target, const void *targinfo)
71 {
72 	const struct xt_connsecmark_target_info *info = targinfo;
73 
74 	switch (info->mode) {
75 	case CONNSECMARK_SAVE:
76 		secmark_save(skb);
77 		break;
78 
79 	case CONNSECMARK_RESTORE:
80 		secmark_restore(skb);
81 		break;
82 
83 	default:
84 		BUG();
85 	}
86 
87 	return XT_CONTINUE;
88 }
89 
90 static bool
91 connsecmark_tg_check(const char *tablename, const void *entry,
92                      const struct xt_target *target, void *targinfo,
93                      unsigned int hook_mask)
94 {
95 	const struct xt_connsecmark_target_info *info = targinfo;
96 
97 	switch (info->mode) {
98 	case CONNSECMARK_SAVE:
99 	case CONNSECMARK_RESTORE:
100 		break;
101 
102 	default:
103 		printk(KERN_INFO PFX "invalid mode: %hu\n", info->mode);
104 		return false;
105 	}
106 
107 	if (nf_ct_l3proto_try_module_get(target->family) < 0) {
108 		printk(KERN_WARNING "can't load conntrack support for "
109 				    "proto=%d\n", target->family);
110 		return false;
111 	}
112 	return true;
113 }
114 
115 static void
116 connsecmark_tg_destroy(const struct xt_target *target, void *targinfo)
117 {
118 	nf_ct_l3proto_module_put(target->family);
119 }
120 
121 static struct xt_target connsecmark_tg_reg[] __read_mostly = {
122 	{
123 		.name		= "CONNSECMARK",
124 		.family		= AF_INET,
125 		.checkentry	= connsecmark_tg_check,
126 		.destroy	= connsecmark_tg_destroy,
127 		.target		= connsecmark_tg,
128 		.targetsize	= sizeof(struct xt_connsecmark_target_info),
129 		.table		= "mangle",
130 		.me		= THIS_MODULE,
131 	},
132 	{
133 		.name		= "CONNSECMARK",
134 		.family		= AF_INET6,
135 		.checkentry	= connsecmark_tg_check,
136 		.destroy	= connsecmark_tg_destroy,
137 		.target		= connsecmark_tg,
138 		.targetsize	= sizeof(struct xt_connsecmark_target_info),
139 		.table		= "mangle",
140 		.me		= THIS_MODULE,
141 	},
142 };
143 
144 static int __init connsecmark_tg_init(void)
145 {
146 	return xt_register_targets(connsecmark_tg_reg,
147 	       ARRAY_SIZE(connsecmark_tg_reg));
148 }
149 
150 static void __exit connsecmark_tg_exit(void)
151 {
152 	xt_unregister_targets(connsecmark_tg_reg,
153 	                      ARRAY_SIZE(connsecmark_tg_reg));
154 }
155 
156 module_init(connsecmark_tg_init);
157 module_exit(connsecmark_tg_exit);
158