1 /*
2 * Copyright (C) 2008 IBM Corporation
3 *
4 * Authors:
5 * Mimi Zohar <zohar@us.ibm.com>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License as
9 * published by the Free Software Foundation, version 2 of the
10 * License.
11 *
12 * File: ima_iint.c
13 * - implements the IMA hooks: ima_inode_alloc, ima_inode_free
14 * - cache integrity information associated with an inode
15 * using a rbtree tree.
16 */
17 #include <linux/slab.h>
18 #include <linux/module.h>
19 #include <linux/spinlock.h>
20 #include <linux/rbtree.h>
21 #include "ima.h"
22
23 static struct rb_root ima_iint_tree = RB_ROOT;
24 static DEFINE_SPINLOCK(ima_iint_lock);
25 static struct kmem_cache *iint_cache __read_mostly;
26
27 int iint_initialized = 0;
28
29 /*
30 * __ima_iint_find - return the iint associated with an inode
31 */
__ima_iint_find(struct inode * inode)32 static struct ima_iint_cache *__ima_iint_find(struct inode *inode)
33 {
34 struct ima_iint_cache *iint;
35 struct rb_node *n = ima_iint_tree.rb_node;
36
37 assert_spin_locked(&ima_iint_lock);
38
39 while (n) {
40 iint = rb_entry(n, struct ima_iint_cache, rb_node);
41
42 if (inode < iint->inode)
43 n = n->rb_left;
44 else if (inode > iint->inode)
45 n = n->rb_right;
46 else
47 break;
48 }
49 if (!n)
50 return NULL;
51
52 return iint;
53 }
54
55 /*
56 * ima_iint_find - return the iint associated with an inode
57 */
ima_iint_find(struct inode * inode)58 struct ima_iint_cache *ima_iint_find(struct inode *inode)
59 {
60 struct ima_iint_cache *iint;
61
62 if (!IS_IMA(inode))
63 return NULL;
64
65 spin_lock(&ima_iint_lock);
66 iint = __ima_iint_find(inode);
67 spin_unlock(&ima_iint_lock);
68
69 return iint;
70 }
71
iint_free(struct ima_iint_cache * iint)72 static void iint_free(struct ima_iint_cache *iint)
73 {
74 iint->version = 0;
75 iint->flags = 0UL;
76 kmem_cache_free(iint_cache, iint);
77 }
78
79 /**
80 * ima_inode_alloc - allocate an iint associated with an inode
81 * @inode: pointer to the inode
82 */
ima_inode_alloc(struct inode * inode)83 int ima_inode_alloc(struct inode *inode)
84 {
85 struct rb_node **p;
86 struct rb_node *new_node, *parent = NULL;
87 struct ima_iint_cache *new_iint, *test_iint;
88 int rc;
89
90 new_iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
91 if (!new_iint)
92 return -ENOMEM;
93
94 new_iint->inode = inode;
95 new_node = &new_iint->rb_node;
96
97 mutex_lock(&inode->i_mutex); /* i_flags */
98 spin_lock(&ima_iint_lock);
99
100 p = &ima_iint_tree.rb_node;
101 while (*p) {
102 parent = *p;
103 test_iint = rb_entry(parent, struct ima_iint_cache, rb_node);
104
105 rc = -EEXIST;
106 if (inode < test_iint->inode)
107 p = &(*p)->rb_left;
108 else if (inode > test_iint->inode)
109 p = &(*p)->rb_right;
110 else
111 goto out_err;
112 }
113
114 inode->i_flags |= S_IMA;
115 rb_link_node(new_node, parent, p);
116 rb_insert_color(new_node, &ima_iint_tree);
117
118 spin_unlock(&ima_iint_lock);
119 mutex_unlock(&inode->i_mutex); /* i_flags */
120
121 return 0;
122 out_err:
123 spin_unlock(&ima_iint_lock);
124 mutex_unlock(&inode->i_mutex); /* i_flags */
125 iint_free(new_iint);
126
127 return rc;
128 }
129
130 /**
131 * ima_inode_free - called on security_inode_free
132 * @inode: pointer to the inode
133 *
134 * Free the integrity information(iint) associated with an inode.
135 */
ima_inode_free(struct inode * inode)136 void ima_inode_free(struct inode *inode)
137 {
138 struct ima_iint_cache *iint;
139
140 if (!IS_IMA(inode))
141 return;
142
143 spin_lock(&ima_iint_lock);
144 iint = __ima_iint_find(inode);
145 rb_erase(&iint->rb_node, &ima_iint_tree);
146 spin_unlock(&ima_iint_lock);
147
148 iint_free(iint);
149 }
150
init_once(void * foo)151 static void init_once(void *foo)
152 {
153 struct ima_iint_cache *iint = foo;
154
155 memset(iint, 0, sizeof *iint);
156 iint->version = 0;
157 iint->flags = 0UL;
158 mutex_init(&iint->mutex);
159 }
160
ima_iintcache_init(void)161 static int __init ima_iintcache_init(void)
162 {
163 iint_cache =
164 kmem_cache_create("iint_cache", sizeof(struct ima_iint_cache), 0,
165 SLAB_PANIC, init_once);
166 iint_initialized = 1;
167 return 0;
168 }
169 security_initcall(ima_iintcache_init);
170