xt_SECMARK.c revision 2809486424df58043b380aeb9d7f402c031c46f6 
1/*
2 * Module for modifying the secmark field of the skb, for use by
3 * security subsystems.
4 *
5 * Based on the nfmark match by:
6 * (C) 1999-2001 Marc Boucher <marc@mbsi.ca>
7 *
8 * (C) 2006 Red Hat, Inc., James Morris <jmorris@redhat.com>
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
13 *
14 */
15#include <linux/module.h>
16#include <linux/skbuff.h>
17#include <linux/selinux.h>
18#include <linux/netfilter/x_tables.h>
19#include <linux/netfilter/xt_SECMARK.h>
20
21MODULE_LICENSE("GPL");
22MODULE_AUTHOR("James Morris <jmorris@redhat.com>");
23MODULE_DESCRIPTION("ip[6]tables SECMARK modification module");
24MODULE_ALIAS("ipt_SECMARK");
25MODULE_ALIAS("ip6t_SECMARK");
26
27#define PFX "SECMARK: "
28
29static u8 mode;
30
31static unsigned int target(struct sk_buff **pskb, const struct net_device *in,
32			   const struct net_device *out, unsigned int hooknum,
33			   const struct xt_target *target,
34			   const void *targinfo)
35{
36	u32 secmark = 0;
37	const struct xt_secmark_target_info *info = targinfo;
38
39	BUG_ON(info->mode != mode);
40
41	switch (mode) {
42	case SECMARK_MODE_SEL:
43		secmark = info->u.sel.selsid;
44		break;
45
46	default:
47		BUG();
48	}
49
50	if ((*pskb)->secmark != secmark)
51		(*pskb)->secmark = secmark;
52
53	return XT_CONTINUE;
54}
55
56static int checkentry_selinux(struct xt_secmark_target_info *info)
57{
58	int err;
59	struct xt_secmark_target_selinux_info *sel = &info->u.sel;
60
61	sel->selctx[SECMARK_SELCTX_MAX - 1] = '\0';
62
63	err = selinux_string_to_sid(sel->selctx, &sel->selsid);
64	if (err) {
65		if (err == -EINVAL)
66			printk(KERN_INFO PFX "invalid SELinux context \'%s\'\n",
67			       sel->selctx);
68		return 0;
69	}
70
71	if (!sel->selsid) {
72		printk(KERN_INFO PFX "unable to map SELinux context \'%s\'\n",
73		       sel->selctx);
74		return 0;
75	}
76
77	err = selinux_relabel_packet_permission(sel->selsid);
78	if (err) {
79		printk(KERN_INFO PFX "unable to obtain relabeling permission\n");
80		return 0;
81	}
82
83	return 1;
84}
85
86static int checkentry(const char *tablename, const void *entry,
87		      const struct xt_target *target, void *targinfo,
88		      unsigned int hook_mask)
89{
90	struct xt_secmark_target_info *info = targinfo;
91
92	if (mode && mode != info->mode) {
93		printk(KERN_INFO PFX "mode already set to %hu cannot mix with "
94		       "rules for mode %hu\n", mode, info->mode);
95		return 0;
96	}
97
98	switch (info->mode) {
99	case SECMARK_MODE_SEL:
100		if (!checkentry_selinux(info))
101			return 0;
102		break;
103
104	default:
105		printk(KERN_INFO PFX "invalid mode: %hu\n", info->mode);
106		return 0;
107	}
108
109	if (!mode)
110		mode = info->mode;
111	return 1;
112}
113
114static struct xt_target xt_secmark_target[] = {
115	{
116		.name		= "SECMARK",
117		.family		= AF_INET,
118		.checkentry	= checkentry,
119		.target		= target,
120		.targetsize	= sizeof(struct xt_secmark_target_info),
121		.table		= "mangle",
122		.me		= THIS_MODULE,
123	},
124	{
125		.name		= "SECMARK",
126		.family		= AF_INET6,
127		.checkentry	= checkentry,
128		.target		= target,
129		.targetsize	= sizeof(struct xt_secmark_target_info),
130		.table		= "mangle",
131		.me		= THIS_MODULE,
132	},
133};
134
135static int __init xt_secmark_init(void)
136{
137	return xt_register_targets(xt_secmark_target,
138				   ARRAY_SIZE(xt_secmark_target));
139}
140
141static void __exit xt_secmark_fini(void)
142{
143	xt_unregister_targets(xt_secmark_target, ARRAY_SIZE(xt_secmark_target));
144}
145
146module_init(xt_secmark_init);
147module_exit(xt_secmark_fini);
148