1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2008 IBM Corporation
4 *
5 * Authors:
6 * Mimi Zohar <zohar@us.ibm.com>
7 *
8 * File: integrity_iint.c
9 * - implements the integrity hooks: integrity_inode_alloc,
10 * integrity_inode_free
11 * - cache integrity information associated with an inode
12 * using a rbtree tree.
13 */
14 #include <linux/slab.h>
15 #include <linux/init.h>
16 #include <linux/spinlock.h>
17 #include <linux/rbtree.h>
18 #include <linux/file.h>
19 #include <linux/uaccess.h>
20 #include <linux/security.h>
21 #include <linux/lsm_hooks.h>
22 #include "integrity.h"
23
24 static struct rb_root integrity_iint_tree = RB_ROOT;
25 static DEFINE_RWLOCK(integrity_iint_lock);
26 static struct kmem_cache *iint_cache __read_mostly;
27
28 struct dentry *integrity_dir;
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 return iint;
47 }
48
49 return NULL;
50 }
51
52 /*
53 * integrity_iint_find - return the iint associated with an inode
54 */
integrity_iint_find(struct inode * inode)55 struct integrity_iint_cache *integrity_iint_find(struct inode *inode)
56 {
57 struct integrity_iint_cache *iint;
58
59 if (!IS_IMA(inode))
60 return NULL;
61
62 read_lock(&integrity_iint_lock);
63 iint = __integrity_iint_find(inode);
64 read_unlock(&integrity_iint_lock);
65
66 return iint;
67 }
68
iint_free(struct integrity_iint_cache * iint)69 static void iint_free(struct integrity_iint_cache *iint)
70 {
71 kfree(iint->ima_hash);
72 iint->ima_hash = NULL;
73 iint->version = 0;
74 iint->flags = 0UL;
75 iint->atomic_flags = 0UL;
76 iint->ima_file_status = INTEGRITY_UNKNOWN;
77 iint->ima_mmap_status = INTEGRITY_UNKNOWN;
78 iint->ima_bprm_status = INTEGRITY_UNKNOWN;
79 iint->ima_read_status = INTEGRITY_UNKNOWN;
80 iint->ima_creds_status = INTEGRITY_UNKNOWN;
81 iint->evm_status = INTEGRITY_UNKNOWN;
82 iint->measured_pcrs = 0;
83 kmem_cache_free(iint_cache, iint);
84 }
85
86 /**
87 * integrity_inode_get - find or allocate an iint associated with an inode
88 * @inode: pointer to the inode
89 * @return: allocated iint
90 *
91 * Caller must lock i_mutex
92 */
integrity_inode_get(struct inode * inode)93 struct integrity_iint_cache *integrity_inode_get(struct inode *inode)
94 {
95 struct rb_node **p;
96 struct rb_node *node, *parent = NULL;
97 struct integrity_iint_cache *iint, *test_iint;
98
99 iint = integrity_iint_find(inode);
100 if (iint)
101 return iint;
102
103 iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
104 if (!iint)
105 return NULL;
106
107 write_lock(&integrity_iint_lock);
108
109 p = &integrity_iint_tree.rb_node;
110 while (*p) {
111 parent = *p;
112 test_iint = rb_entry(parent, struct integrity_iint_cache,
113 rb_node);
114 if (inode < test_iint->inode) {
115 p = &(*p)->rb_left;
116 } else if (inode > test_iint->inode) {
117 p = &(*p)->rb_right;
118 } else {
119 write_unlock(&integrity_iint_lock);
120 kmem_cache_free(iint_cache, iint);
121 return test_iint;
122 }
123 }
124
125 iint->inode = inode;
126 node = &iint->rb_node;
127 inode->i_flags |= S_IMA;
128 rb_link_node(node, parent, p);
129 rb_insert_color(node, &integrity_iint_tree);
130
131 write_unlock(&integrity_iint_lock);
132 return iint;
133 }
134
135 /**
136 * integrity_inode_free - called on security_inode_free
137 * @inode: pointer to the inode
138 *
139 * Free the integrity information(iint) associated with an inode.
140 */
integrity_inode_free(struct inode * inode)141 void integrity_inode_free(struct inode *inode)
142 {
143 struct integrity_iint_cache *iint;
144
145 if (!IS_IMA(inode))
146 return;
147
148 write_lock(&integrity_iint_lock);
149 iint = __integrity_iint_find(inode);
150 rb_erase(&iint->rb_node, &integrity_iint_tree);
151 write_unlock(&integrity_iint_lock);
152
153 iint_free(iint);
154 }
155
init_once(void * foo)156 static void init_once(void *foo)
157 {
158 struct integrity_iint_cache *iint = (struct integrity_iint_cache *) foo;
159
160 memset(iint, 0, sizeof(*iint));
161 iint->ima_file_status = INTEGRITY_UNKNOWN;
162 iint->ima_mmap_status = INTEGRITY_UNKNOWN;
163 iint->ima_bprm_status = INTEGRITY_UNKNOWN;
164 iint->ima_read_status = INTEGRITY_UNKNOWN;
165 iint->ima_creds_status = INTEGRITY_UNKNOWN;
166 iint->evm_status = INTEGRITY_UNKNOWN;
167 mutex_init(&iint->mutex);
168 }
169
integrity_iintcache_init(void)170 static int __init integrity_iintcache_init(void)
171 {
172 iint_cache =
173 kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
174 0, SLAB_PANIC, init_once);
175 return 0;
176 }
177 DEFINE_LSM(integrity) = {
178 .name = "integrity",
179 .init = integrity_iintcache_init,
180 .order = LSM_ORDER_LAST,
181 };
182
183
184 /*
185 * integrity_kernel_read - read data from the file
186 *
187 * This is a function for reading file content instead of kernel_read().
188 * It does not perform locking checks to ensure it cannot be blocked.
189 * It does not perform security checks because it is irrelevant for IMA.
190 *
191 */
integrity_kernel_read(struct file * file,loff_t offset,void * addr,unsigned long count)192 int integrity_kernel_read(struct file *file, loff_t offset,
193 void *addr, unsigned long count)
194 {
195 return __kernel_read(file, addr, count, &offset);
196 }
197
198 /*
199 * integrity_load_keys - load integrity keys hook
200 *
201 * Hooks is called from init/main.c:kernel_init_freeable()
202 * when rootfs is ready
203 */
integrity_load_keys(void)204 void __init integrity_load_keys(void)
205 {
206 ima_load_x509();
207
208 if (!IS_ENABLED(CONFIG_IMA_LOAD_X509))
209 evm_load_x509();
210 }
211
integrity_fs_init(void)212 static int __init integrity_fs_init(void)
213 {
214 integrity_dir = securityfs_create_dir("integrity", NULL);
215 if (IS_ERR(integrity_dir)) {
216 int ret = PTR_ERR(integrity_dir);
217
218 if (ret != -ENODEV)
219 pr_err("Unable to create integrity sysfs dir: %d\n",
220 ret);
221 integrity_dir = NULL;
222 return ret;
223 }
224
225 return 0;
226 }
227
228 late_initcall(integrity_fs_init)
229
