aboutsummaryrefslogtreecommitdiff
path: root/security/integrity/ima/ima_iint.c
blob: c442e47b67853099e776c4e5b95dd3fa321183ae (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
/*
 * Copyright (C) 2008 IBM Corporation
 *
 * Authors:
 * Mimi Zohar <zohar@us.ibm.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation, version 2 of the
 * License.
 *
 * File: ima_iint.c
 * 	- implements the IMA hooks: ima_inode_alloc, ima_inode_free
 *	- cache integrity information associated with an inode
 *	  using a rbtree tree.
 */
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/rbtree.h>
#include "ima.h"

static struct rb_root ima_iint_tree = RB_ROOT;
static DEFINE_SPINLOCK(ima_iint_lock);
static struct kmem_cache *iint_cache __read_mostly;

int iint_initialized = 0;

/*
 * __ima_iint_find - return the iint associated with an inode
 */
static struct ima_iint_cache *__ima_iint_find(struct inode *inode)
{
	struct ima_iint_cache *iint;
	struct rb_node *n = ima_iint_tree.rb_node;

	assert_spin_locked(&ima_iint_lock);

	while (n) {
		iint = rb_entry(n, struct ima_iint_cache, rb_node);

		if (inode < iint->inode)
			n = n->rb_left;
		else if (inode > iint->inode)
			n = n->rb_right;
		else
			break;
	}
	if (!n)
		return NULL;

	return iint;
}

/*
 * ima_iint_find - return the iint associated with an inode
 */
struct ima_iint_cache *ima_iint_find(struct inode *inode)
{
	struct ima_iint_cache *iint;

	if (!IS_IMA(inode))
		return NULL;

	spin_lock(&ima_iint_lock);
	iint = __ima_iint_find(inode);
	spin_unlock(&ima_iint_lock);

	return iint;
}

static void iint_free(struct ima_iint_cache *iint)
{
	iint->version = 0;
	iint->flags = 0UL;
	kmem_cache_free(iint_cache, iint);
}

/**
 * ima_inode_alloc - allocate an iint associated with an inode
 * @inode: pointer to the inode
 */
int ima_inode_alloc(struct inode *inode)
{
	struct rb_node **p;
	struct rb_node *new_node, *parent = NULL;
	struct ima_iint_cache *new_iint, *test_iint;
	int rc;

	new_iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
	if (!new_iint)
		return -ENOMEM;

	new_iint->inode = inode;
	new_node = &new_iint->rb_node;

	mutex_lock(&inode->i_mutex); /* i_flags */
	spin_lock(&ima_iint_lock);

	p = &ima_iint_tree.rb_node;
	while (*p) {
		parent = *p;
		test_iint = rb_entry(parent, struct ima_iint_cache, rb_node);

		rc = -EEXIST;
		if (inode < test_iint->inode)
			p = &(*p)->rb_left;
		else if (inode > test_iint->inode)
			p = &(*p)->rb_right;
		else
			goto out_err;
	}

	inode->i_flags |= S_IMA;
	rb_link_node(new_node, parent, p);
	rb_insert_color(new_node, &ima_iint_tree);

	spin_unlock(&ima_iint_lock);
	mutex_unlock(&inode->i_mutex); /* i_flags */

	return 0;
out_err:
	spin_unlock(&ima_iint_lock);
	mutex_unlock(&inode->i_mutex); /* i_flags */
	iint_free(new_iint);

	return rc;
}

/**
 * ima_inode_free - called on security_inode_free
 * @inode: pointer to the inode
 *
 * Free the integrity information(iint) associated with an inode.
 */
void ima_inode_free(struct inode *inode)
{
	struct ima_iint_cache *iint;

	if (inode->i_readcount)
		printk(KERN_INFO "%s: readcount: %u\n", __func__, inode->i_readcount);

	inode->i_readcount = 0;

	if (!IS_IMA(inode))
		return;

	spin_lock(&ima_iint_lock);
	iint = __ima_iint_find(inode);
	rb_erase(&iint->rb_node, &ima_iint_tree);
	spin_unlock(&ima_iint_lock);

	iint_free(iint);
}

static void init_once(void *foo)
{
	struct ima_iint_cache *iint = foo;

	memset(iint, 0, sizeof *iint);
	iint->version = 0;
	iint->flags = 0UL;
	mutex_init(&iint->mutex);
}

static int __init ima_iintcache_init(void)
{
	iint_cache =
	    kmem_cache_create("iint_cache", sizeof(struct ima_iint_cache), 0,
			      SLAB_PANIC, init_once);
	iint_initialized = 1;
	return 0;
}
security_initcall(ima_iintcache_init);