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->ima_file_status = INTEGRITY_UNKNOWN;
78 iint->ima_mmap_status = INTEGRITY_UNKNOWN;
79 iint->ima_bprm_status = INTEGRITY_UNKNOWN;
80 iint->ima_module_status = INTEGRITY_UNKNOWN;
81 iint->evm_status = INTEGRITY_UNKNOWN;
82 kmem_cache_free(iint_cache, iint);
83 }
84
85 /**
86 * integrity_inode_get - find or allocate an iint associated with an inode
87 * @inode: pointer to the inode
88 * @return: allocated iint
89 *
90 * Caller must lock i_mutex
91 */
integrity_inode_get(struct inode * inode)92 struct integrity_iint_cache *integrity_inode_get(struct inode *inode)
93 {
94 struct rb_node **p;
95 struct rb_node *node, *parent = NULL;
96 struct integrity_iint_cache *iint, *test_iint;
97
98 iint = integrity_iint_find(inode);
99 if (iint)
100 return iint;
101
102 iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
103 if (!iint)
104 return NULL;
105
106 write_lock(&integrity_iint_lock);
107
108 p = &integrity_iint_tree.rb_node;
109 while (*p) {
110 parent = *p;
111 test_iint = rb_entry(parent, struct integrity_iint_cache,
112 rb_node);
113 if (inode < test_iint->inode)
114 p = &(*p)->rb_left;
115 else
116 p = &(*p)->rb_right;
117 }
118
119 iint->inode = inode;
120 node = &iint->rb_node;
121 inode->i_flags |= S_IMA;
122 rb_link_node(node, parent, p);
123 rb_insert_color(node, &integrity_iint_tree);
124
125 write_unlock(&integrity_iint_lock);
126 return iint;
127 }
128
129 /**
130 * integrity_inode_free - called on security_inode_free
131 * @inode: pointer to the inode
132 *
133 * Free the integrity information(iint) associated with an inode.
134 */
integrity_inode_free(struct inode * inode)135 void integrity_inode_free(struct inode *inode)
136 {
137 struct integrity_iint_cache *iint;
138
139 if (!IS_IMA(inode))
140 return;
141
142 write_lock(&integrity_iint_lock);
143 iint = __integrity_iint_find(inode);
144 rb_erase(&iint->rb_node, &integrity_iint_tree);
145 write_unlock(&integrity_iint_lock);
146
147 iint_free(iint);
148 }
149
init_once(void * foo)150 static void init_once(void *foo)
151 {
152 struct integrity_iint_cache *iint = foo;
153
154 memset(iint, 0, sizeof(*iint));
155 iint->version = 0;
156 iint->flags = 0UL;
157 iint->ima_file_status = INTEGRITY_UNKNOWN;
158 iint->ima_mmap_status = INTEGRITY_UNKNOWN;
159 iint->ima_bprm_status = INTEGRITY_UNKNOWN;
160 iint->ima_module_status = INTEGRITY_UNKNOWN;
161 iint->evm_status = INTEGRITY_UNKNOWN;
162 }
163
integrity_iintcache_init(void)164 static int __init integrity_iintcache_init(void)
165 {
166 iint_cache =
167 kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
168 0, SLAB_PANIC, init_once);
169 return 0;
170 }
171 security_initcall(integrity_iintcache_init);
172
173
174 /*
175 * integrity_kernel_read - read data from the file
176 *
177 * This is a function for reading file content instead of kernel_read().
178 * It does not perform locking checks to ensure it cannot be blocked.
179 * It does not perform security checks because it is irrelevant for IMA.
180 *
181 */
integrity_kernel_read(struct file * file,loff_t offset,char * addr,unsigned long count)182 int integrity_kernel_read(struct file *file, loff_t offset,
183 char *addr, unsigned long count)
184 {
185 mm_segment_t old_fs;
186 char __user *buf = (char __user *)addr;
187 ssize_t ret;
188
189 if (!(file->f_mode & FMODE_READ))
190 return -EBADF;
191
192 old_fs = get_fs();
193 set_fs(get_ds());
194 ret = __vfs_read(file, buf, count, &offset);
195 set_fs(old_fs);
196
197 return ret;
198 }
199
200 /*
201 * integrity_read_file - read entire file content into the buffer
202 *
203 * This is function opens a file, allocates the buffer of required
204 * size, read entire file content to the buffer and closes the file
205 *
206 * It is used only by init code.
207 *
208 */
integrity_read_file(const char * path,char ** data)209 int __init integrity_read_file(const char *path, char **data)
210 {
211 struct file *file;
212 loff_t size;
213 char *buf;
214 int rc = -EINVAL;
215
216 if (!path || !*path)
217 return -EINVAL;
218
219 file = filp_open(path, O_RDONLY, 0);
220 if (IS_ERR(file)) {
221 rc = PTR_ERR(file);
222 pr_err("Unable to open file: %s (%d)", path, rc);
223 return rc;
224 }
225
226 size = i_size_read(file_inode(file));
227 if (size <= 0)
228 goto out;
229
230 buf = kmalloc(size, GFP_KERNEL);
231 if (!buf) {
232 rc = -ENOMEM;
233 goto out;
234 }
235
236 rc = integrity_kernel_read(file, 0, buf, size);
237 if (rc < 0)
238 kfree(buf);
239 else if (rc != size)
240 rc = -EIO;
241 else
242 *data = buf;
243 out:
244 fput(file);
245 return rc;
246 }
247
248 /*
249 * integrity_load_keys - load integrity keys hook
250 *
251 * Hooks is called from init/main.c:kernel_init_freeable()
252 * when rootfs is ready
253 */
integrity_load_keys(void)254 void __init integrity_load_keys(void)
255 {
256 ima_load_x509();
257 }
258