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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 radix tree. | |
16 | */ | |
17 | #include <linux/module.h> | |
18 | #include <linux/spinlock.h> | |
19 | #include <linux/radix-tree.h> | |
20 | #include "ima.h" | |
21 | ||
22 | #define ima_iint_delete ima_inode_free | |
23 | ||
24 | RADIX_TREE(ima_iint_store, GFP_ATOMIC); | |
25 | DEFINE_SPINLOCK(ima_iint_lock); | |
26 | ||
27 | static struct kmem_cache *iint_cache __read_mostly; | |
28 | ||
29 | /* ima_iint_find_get - return the iint associated with an inode | |
30 | * | |
31 | * ima_iint_find_get gets a reference to the iint. Caller must | |
32 | * remember to put the iint reference. | |
33 | */ | |
34 | struct ima_iint_cache *ima_iint_find_get(struct inode *inode) | |
35 | { | |
36 | struct ima_iint_cache *iint; | |
37 | ||
38 | rcu_read_lock(); | |
39 | iint = radix_tree_lookup(&ima_iint_store, (unsigned long)inode); | |
40 | if (!iint) | |
41 | goto out; | |
42 | kref_get(&iint->refcount); | |
43 | out: | |
44 | rcu_read_unlock(); | |
45 | return iint; | |
46 | } | |
47 | ||
48 | /* Allocate memory for the iint associated with the inode | |
49 | * from the iint_cache slab, initialize the iint, and | |
50 | * insert it into the radix tree. | |
51 | * | |
52 | * On success return a pointer to the iint; on failure return NULL. | |
53 | */ | |
54 | struct ima_iint_cache *ima_iint_insert(struct inode *inode) | |
55 | { | |
56 | struct ima_iint_cache *iint = NULL; | |
57 | int rc = 0; | |
58 | ||
59 | if (!ima_initialized) | |
60 | return iint; | |
61 | iint = kmem_cache_alloc(iint_cache, GFP_KERNEL); | |
62 | if (!iint) | |
63 | return iint; | |
64 | ||
65 | rc = radix_tree_preload(GFP_KERNEL); | |
66 | if (rc < 0) | |
67 | goto out; | |
68 | ||
69 | spin_lock(&ima_iint_lock); | |
70 | rc = radix_tree_insert(&ima_iint_store, (unsigned long)inode, iint); | |
71 | spin_unlock(&ima_iint_lock); | |
72 | out: | |
73 | if (rc < 0) { | |
74 | kmem_cache_free(iint_cache, iint); | |
75 | if (rc == -EEXIST) { | |
76 | iint = radix_tree_lookup(&ima_iint_store, | |
77 | (unsigned long)inode); | |
78 | } else | |
79 | iint = NULL; | |
80 | } | |
81 | radix_tree_preload_end(); | |
82 | return iint; | |
83 | } | |
84 | ||
85 | /** | |
86 | * ima_inode_alloc - allocate an iint associated with an inode | |
87 | * @inode: pointer to the inode | |
88 | * | |
89 | * Return 0 on success, 1 on failure. | |
90 | */ | |
91 | int ima_inode_alloc(struct inode *inode) | |
92 | { | |
93 | struct ima_iint_cache *iint; | |
94 | ||
95 | if (!ima_initialized) | |
96 | return 0; | |
97 | ||
98 | iint = ima_iint_insert(inode); | |
99 | if (!iint) | |
100 | return 1; | |
101 | return 0; | |
102 | } | |
103 | ||
104 | /* ima_iint_find_insert_get - get the iint associated with an inode | |
105 | * | |
106 | * Most insertions are done at inode_alloc, except those allocated | |
107 | * before late_initcall. When the iint does not exist, allocate it, | |
108 | * initialize and insert it, and increment the iint refcount. | |
109 | * | |
110 | * (Can't initialize at security_initcall before any inodes are | |
111 | * allocated, got to wait at least until proc_init.) | |
112 | * | |
113 | * Return the iint. | |
114 | */ | |
115 | struct ima_iint_cache *ima_iint_find_insert_get(struct inode *inode) | |
116 | { | |
117 | struct ima_iint_cache *iint = NULL; | |
118 | ||
119 | iint = ima_iint_find_get(inode); | |
120 | if (iint) | |
121 | return iint; | |
122 | ||
123 | iint = ima_iint_insert(inode); | |
124 | if (iint) | |
125 | kref_get(&iint->refcount); | |
126 | ||
127 | return iint; | |
128 | } | |
129 | ||
130 | /* iint_free - called when the iint refcount goes to zero */ | |
131 | void iint_free(struct kref *kref) | |
132 | { | |
133 | struct ima_iint_cache *iint = container_of(kref, struct ima_iint_cache, | |
134 | refcount); | |
135 | iint->version = 0; | |
136 | iint->flags = 0UL; | |
137 | kref_set(&iint->refcount, 1); | |
138 | kmem_cache_free(iint_cache, iint); | |
139 | } | |
140 | ||
141 | void iint_rcu_free(struct rcu_head *rcu_head) | |
142 | { | |
143 | struct ima_iint_cache *iint = container_of(rcu_head, | |
144 | struct ima_iint_cache, rcu); | |
145 | kref_put(&iint->refcount, iint_free); | |
146 | } | |
147 | ||
148 | /** | |
149 | * ima_iint_delete - called on integrity_inode_free | |
150 | * @inode: pointer to the inode | |
151 | * | |
152 | * Free the integrity information(iint) associated with an inode. | |
153 | */ | |
154 | void ima_iint_delete(struct inode *inode) | |
155 | { | |
156 | struct ima_iint_cache *iint; | |
157 | ||
158 | if (!ima_initialized) | |
159 | return; | |
160 | spin_lock(&ima_iint_lock); | |
161 | iint = radix_tree_delete(&ima_iint_store, (unsigned long)inode); | |
162 | spin_unlock(&ima_iint_lock); | |
163 | if (iint) | |
164 | call_rcu(&iint->rcu, iint_rcu_free); | |
165 | } | |
166 | ||
167 | static void init_once(void *foo) | |
168 | { | |
169 | struct ima_iint_cache *iint = foo; | |
170 | ||
171 | memset(iint, 0, sizeof *iint); | |
172 | iint->version = 0; | |
173 | iint->flags = 0UL; | |
174 | mutex_init(&iint->mutex); | |
175 | iint->readcount = 0; | |
176 | iint->writecount = 0; | |
177 | kref_set(&iint->refcount, 1); | |
178 | } | |
179 | ||
180 | void ima_iintcache_init(void) | |
181 | { | |
182 | iint_cache = | |
183 | kmem_cache_create("iint_cache", sizeof(struct ima_iint_cache), 0, | |
184 | SLAB_PANIC, init_once); | |
185 | } |