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	(*pskb)->secmark = secmark;
51	return XT_CONTINUE;
52}
53
54static int checkentry_selinux(struct xt_secmark_target_info *info)
55{
56	int err;
57	struct xt_secmark_target_selinux_info *sel = &info->u.sel;
58
59	sel->selctx[SECMARK_SELCTX_MAX - 1] = '\0';
60
61	err = selinux_string_to_sid(sel->selctx, &sel->selsid);
62	if (err) {
63		if (err == -EINVAL)
64			printk(KERN_INFO PFX "invalid SELinux context \'%s\'\n",
65			       sel->selctx);
66		return 0;
67	}
68
69	if (!sel->selsid) {
70		printk(KERN_INFO PFX "unable to map SELinux context \'%s\'\n",
71		       sel->selctx);
72		return 0;
73	}
74
75	err = selinux_relabel_packet_permission(sel->selsid);
76	if (err) {
77		printk(KERN_INFO PFX "unable to obtain relabeling permission\n");
78		return 0;
79	}
80
81	return 1;
82}
83
84static int checkentry(const char *tablename, const void *entry,
85		      const struct xt_target *target, void *targinfo,
86		      unsigned int hook_mask)
87{
88	struct xt_secmark_target_info *info = targinfo;
89
90	if (mode && mode != info->mode) {
91		printk(KERN_INFO PFX "mode already set to %hu cannot mix with "
92		       "rules for mode %hu\n", mode, info->mode);
93		return 0;
94	}
95
96	switch (info->mode) {
97	case SECMARK_MODE_SEL:
98		if (!checkentry_selinux(info))
99			return 0;
100		break;
101
102	default:
103		printk(KERN_INFO PFX "invalid mode: %hu\n", info->mode);
104		return 0;
105	}
106
107	if (!mode)
108		mode = info->mode;
109	return 1;
110}
111
112static struct xt_target xt_secmark_target[] = {
113	{
114		.name		= "SECMARK",
115		.family		= AF_INET,
116		.checkentry	= checkentry,
117		.target		= target,
118		.targetsize	= sizeof(struct xt_secmark_target_info),
119		.table		= "mangle",
120		.me		= THIS_MODULE,
121	},
122	{
123		.name		= "SECMARK",
124		.family		= AF_INET6,
125		.checkentry	= checkentry,
126		.target		= target,
127		.targetsize	= sizeof(struct xt_secmark_target_info),
128		.table		= "mangle",
129		.me		= THIS_MODULE,
130	},
131};
132
133static int __init xt_secmark_init(void)
134{
135	return xt_register_targets(xt_secmark_target,
136				   ARRAY_SIZE(xt_secmark_target));
137}
138
139static void __exit xt_secmark_fini(void)
140{
141	xt_unregister_targets(xt_secmark_target, ARRAY_SIZE(xt_secmark_target));
142}
143
144module_init(xt_secmark_init);
145module_exit(xt_secmark_fini);
146