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: integrity_iint.c
13 * - implements the integrity hooks: integrity_inode_alloc,
14 * integrity_inode_free
15 * - cache integrity information associated with an inode
16 * using a rbtree tree.
17 */
18 #include <linux/slab.h>
19 #include <linux/module.h>
20 #include <linux/spinlock.h>
21 #include <linux/rbtree.h>
22 #include <linux/file.h>
23 #include <linux/uaccess.h>
24 #include "integrity.h"
25
26 static struct rb_root integrity_iint_tree = RB_ROOT;
27 static DEFINE_RWLOCK(integrity_iint_lock);
28 static struct kmem_cache *iint_cache __read_mostly;
29
30 /*
31 * __integrity_iint_find - return the iint associated with an inode
32 */
__integrity_iint_find(struct inode * inode)33 static struct integrity_iint_cache *__integrity_iint_find(struct inode *inode)
34 {
35 struct integrity_iint_cache *iint;
36 struct rb_node *n = integrity_iint_tree.rb_node;
37
38 while (n) {
39 iint = rb_entry(n, struct integrity_iint_cache, rb_node);
40
41 if (inode < iint->inode)
42 n = n->rb_left;
43 else if (inode > iint->inode)
44 n = n->rb_right;
45 else
46 break;
47 }
48 if (!n)
49 return NULL;
50
51 return iint;
52 }
53
54 /*
55 * integrity_iint_find - return the iint associated with an inode
56 */
integrity_iint_find(struct inode * inode)57 struct integrity_iint_cache *integrity_iint_find(struct inode *inode)
58 {
59 struct integrity_iint_cache *iint;
60
61 if (!IS_IMA(inode))
62 return NULL;
63
64 read_lock(&integrity_iint_lock);
65 iint = __integrity_iint_find(inode);
66 read_unlock(&integrity_iint_lock);
67
68 return iint;
69 }
70
iint_free(struct integrity_iint_cache * iint)71 static void iint_free(struct integrity_iint_cache *iint)
72 {
73 kfree(iint->ima_hash);
74 iint->ima_hash = NULL;
75 iint->version = 0;
76 iint->flags = 0UL;
77 iint->atomic_flags = 0UL;
78 iint->ima_file_status = INTEGRITY_UNKNOWN;
79 iint->ima_mmap_status = INTEGRITY_UNKNOWN;
80 iint->ima_bprm_status = INTEGRITY_UNKNOWN;
81 iint->ima_read_status = INTEGRITY_UNKNOWN;
82 iint->evm_status = INTEGRITY_UNKNOWN;
83 iint->measured_pcrs = 0;
84 kmem_cache_free(iint_cache, iint);
85 }
86
87 /**
88 * integrity_inode_get - find or allocate an iint associated with an inode
89 * @inode: pointer to the inode
90 * @return: allocated iint
91 *
92 * Caller must lock i_mutex
93 */
integrity_inode_get(struct inode * inode)94 struct integrity_iint_cache *integrity_inode_get(struct inode *inode)
95 {
96 struct rb_node **p;
97 struct rb_node *node, *parent = NULL;
98 struct integrity_iint_cache *iint, *test_iint;
99
100 iint = integrity_iint_find(inode);
101 if (iint)
102 return iint;
103
104 iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
105 if (!iint)
106 return NULL;
107
108 write_lock(&integrity_iint_lock);
109
110 p = &integrity_iint_tree.rb_node;
111 while (*p) {
112 parent = *p;
113 test_iint = rb_entry(parent, struct integrity_iint_cache,
114 rb_node);
115 if (inode < test_iint->inode)
116 p = &(*p)->rb_left;
117 else
118 p = &(*p)->rb_right;
119 }
120
121 iint->inode = inode;
122 node = &iint->rb_node;
123 inode->i_flags |= S_IMA;
124 rb_link_node(node, parent, p);
125 rb_insert_color(node, &integrity_iint_tree);
126
127 write_unlock(&integrity_iint_lock);
128 return iint;
129 }
130
131 /**
132 * integrity_inode_free - called on security_inode_free
133 * @inode: pointer to the inode
134 *
135 * Free the integrity information(iint) associated with an inode.
136 */
integrity_inode_free(struct inode * inode)137 void integrity_inode_free(struct inode *inode)
138 {
139 struct integrity_iint_cache *iint;
140
141 if (!IS_IMA(inode))
142 return;
143
144 write_lock(&integrity_iint_lock);
145 iint = __integrity_iint_find(inode);
146 rb_erase(&iint->rb_node, &integrity_iint_tree);
147 write_unlock(&integrity_iint_lock);
148
149 iint_free(iint);
150 }
151
init_once(void * foo)152 static void init_once(void *foo)
153 {
154 struct integrity_iint_cache *iint = foo;
155
156 memset(iint, 0, sizeof(*iint));
157 iint->version = 0;
158 iint->flags = 0UL;
159 iint->atomic_flags = 0;
160 iint->ima_file_status = INTEGRITY_UNKNOWN;
161 iint->ima_mmap_status = INTEGRITY_UNKNOWN;
162 iint->ima_bprm_status = INTEGRITY_UNKNOWN;
163 iint->ima_read_status = INTEGRITY_UNKNOWN;
164 iint->evm_status = INTEGRITY_UNKNOWN;
165 iint->measured_pcrs = 0;
166 mutex_init(&iint->mutex);
167 }
168
integrity_iintcache_init(void)169 static int __init integrity_iintcache_init(void)
170 {
171 iint_cache =
172 kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
173 0, SLAB_PANIC, init_once);
174 return 0;
175 }
176 security_initcall(integrity_iintcache_init);
177
178
179 /*
180 * integrity_kernel_read - read data from the file
181 *
182 * This is a function for reading file content instead of kernel_read().
183 * It does not perform locking checks to ensure it cannot be blocked.
184 * It does not perform security checks because it is irrelevant for IMA.
185 *
186 */
integrity_kernel_read(struct file * file,loff_t offset,void * addr,unsigned long count)187 int integrity_kernel_read(struct file *file, loff_t offset,
188 void *addr, unsigned long count)
189 {
190 mm_segment_t old_fs;
191 char __user *buf = (char __user *)addr;
192 ssize_t ret;
193
194 if (!(file->f_mode & FMODE_READ))
195 return -EBADF;
196
197 old_fs = get_fs();
198 set_fs(get_ds());
199 ret = __vfs_read(file, buf, count, &offset);
200 set_fs(old_fs);
201
202 return ret;
203 }
204
205 /*
206 * integrity_read_file - read entire file content into the buffer
207 *
208 * This is function opens a file, allocates the buffer of required
209 * size, read entire file content to the buffer and closes the file
210 *
211 * It is used only by init code.
212 *
213 */
integrity_read_file(const char * path,char ** data)214 int __init integrity_read_file(const char *path, char **data)
215 {
216 struct file *file;
217 loff_t size;
218 char *buf;
219 int rc = -EINVAL;
220
221 if (!path || !*path)
222 return -EINVAL;
223
224 file = filp_open(path, O_RDONLY, 0);
225 if (IS_ERR(file)) {
226 rc = PTR_ERR(file);
227 pr_err("Unable to open file: %s (%d)", path, rc);
228 return rc;
229 }
230
231 size = i_size_read(file_inode(file));
232 if (size <= 0)
233 goto out;
234
235 buf = kmalloc(size, GFP_KERNEL);
236 if (!buf) {
237 rc = -ENOMEM;
238 goto out;
239 }
240
241 rc = integrity_kernel_read(file, 0, buf, size);
242 if (rc == size) {
243 *data = buf;
244 } else {
245 kfree(buf);
246 if (rc >= 0)
247 rc = -EIO;
248 }
249 out:
250 fput(file);
251 return rc;
252 }
253
254 /*
255 * integrity_load_keys - load integrity keys hook
256 *
257 * Hooks is called from init/main.c:kernel_init_freeable()
258 * when rootfs is ready
259 */
integrity_load_keys(void)260 void __init integrity_load_keys(void)
261 {
262 ima_load_x509();
263 evm_load_x509();
264 }
265