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
69 #define IMA_MAX_NESTING (FILESYSTEM_MAX_STACK_DEPTH+1)
70
71 /*
72 * It is not clear that IMA should be nested at all, but as long is it measures
73 * files both on overlayfs and on underlying fs, we need to annotate the iint
74 * mutex to avoid lockdep false positives related to IMA + overlayfs.
75 * See ovl_lockdep_annotate_inode_mutex_key() for more details.
76 */
iint_lockdep_annotate(struct integrity_iint_cache * iint,struct inode * inode)77 static inline void iint_lockdep_annotate(struct integrity_iint_cache *iint,
78 struct inode *inode)
79 {
80 #ifdef CONFIG_LOCKDEP
81 static struct lock_class_key iint_mutex_key[IMA_MAX_NESTING];
82
83 int depth = inode->i_sb->s_stack_depth;
84
85 if (WARN_ON_ONCE(depth < 0 || depth >= IMA_MAX_NESTING))
86 depth = 0;
87
88 lockdep_set_class(&iint->mutex, &iint_mutex_key[depth]);
89 #endif
90 }
91
iint_init_always(struct integrity_iint_cache * iint,struct inode * inode)92 static void iint_init_always(struct integrity_iint_cache *iint,
93 struct inode *inode)
94 {
95 iint->ima_hash = NULL;
96 iint->version = 0;
97 iint->flags = 0UL;
98 iint->atomic_flags = 0UL;
99 iint->ima_file_status = INTEGRITY_UNKNOWN;
100 iint->ima_mmap_status = INTEGRITY_UNKNOWN;
101 iint->ima_bprm_status = INTEGRITY_UNKNOWN;
102 iint->ima_read_status = INTEGRITY_UNKNOWN;
103 iint->ima_creds_status = INTEGRITY_UNKNOWN;
104 iint->evm_status = INTEGRITY_UNKNOWN;
105 iint->measured_pcrs = 0;
106 mutex_init(&iint->mutex);
107 iint_lockdep_annotate(iint, inode);
108 }
109
iint_free(struct integrity_iint_cache * iint)110 static void iint_free(struct integrity_iint_cache *iint)
111 {
112 kfree(iint->ima_hash);
113 mutex_destroy(&iint->mutex);
114 kmem_cache_free(iint_cache, iint);
115 }
116
117 /**
118 * integrity_inode_get - find or allocate an iint associated with an inode
119 * @inode: pointer to the inode
120 * @return: allocated iint
121 *
122 * Caller must lock i_mutex
123 */
integrity_inode_get(struct inode * inode)124 struct integrity_iint_cache *integrity_inode_get(struct inode *inode)
125 {
126 struct rb_node **p;
127 struct rb_node *node, *parent = NULL;
128 struct integrity_iint_cache *iint, *test_iint;
129
130 iint = integrity_iint_find(inode);
131 if (iint)
132 return iint;
133
134 iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
135 if (!iint)
136 return NULL;
137
138 iint_init_always(iint, inode);
139
140 write_lock(&integrity_iint_lock);
141
142 p = &integrity_iint_tree.rb_node;
143 while (*p) {
144 parent = *p;
145 test_iint = rb_entry(parent, struct integrity_iint_cache,
146 rb_node);
147 if (inode < test_iint->inode) {
148 p = &(*p)->rb_left;
149 } else if (inode > test_iint->inode) {
150 p = &(*p)->rb_right;
151 } else {
152 write_unlock(&integrity_iint_lock);
153 kmem_cache_free(iint_cache, iint);
154 return test_iint;
155 }
156 }
157
158 iint->inode = inode;
159 node = &iint->rb_node;
160 inode->i_flags |= S_IMA;
161 rb_link_node(node, parent, p);
162 rb_insert_color(node, &integrity_iint_tree);
163
164 write_unlock(&integrity_iint_lock);
165 return iint;
166 }
167
168 /**
169 * integrity_inode_free - called on security_inode_free
170 * @inode: pointer to the inode
171 *
172 * Free the integrity information(iint) associated with an inode.
173 */
integrity_inode_free(struct inode * inode)174 void integrity_inode_free(struct inode *inode)
175 {
176 struct integrity_iint_cache *iint;
177
178 if (!IS_IMA(inode))
179 return;
180
181 write_lock(&integrity_iint_lock);
182 iint = __integrity_iint_find(inode);
183 rb_erase(&iint->rb_node, &integrity_iint_tree);
184 write_unlock(&integrity_iint_lock);
185
186 iint_free(iint);
187 }
188
iint_init_once(void * foo)189 static void iint_init_once(void *foo)
190 {
191 struct integrity_iint_cache *iint = (struct integrity_iint_cache *) foo;
192
193 memset(iint, 0, sizeof(*iint));
194 }
195
integrity_iintcache_init(void)196 static int __init integrity_iintcache_init(void)
197 {
198 iint_cache =
199 kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
200 0, SLAB_PANIC, iint_init_once);
201 return 0;
202 }
203 DEFINE_LSM(integrity) = {
204 .name = "integrity",
205 .init = integrity_iintcache_init,
206 .order = LSM_ORDER_LAST,
207 };
208
209
210 /*
211 * integrity_kernel_read - read data from the file
212 *
213 * This is a function for reading file content instead of kernel_read().
214 * It does not perform locking checks to ensure it cannot be blocked.
215 * It does not perform security checks because it is irrelevant for IMA.
216 *
217 */
integrity_kernel_read(struct file * file,loff_t offset,void * addr,unsigned long count)218 int integrity_kernel_read(struct file *file, loff_t offset,
219 void *addr, unsigned long count)
220 {
221 return __kernel_read(file, addr, count, &offset);
222 }
223
224 /*
225 * integrity_load_keys - load integrity keys hook
226 *
227 * Hooks is called from init/main.c:kernel_init_freeable()
228 * when rootfs is ready
229 */
integrity_load_keys(void)230 void __init integrity_load_keys(void)
231 {
232 ima_load_x509();
233
234 if (!IS_ENABLED(CONFIG_IMA_LOAD_X509))
235 evm_load_x509();
236 }
237
integrity_fs_init(void)238 static int __init integrity_fs_init(void)
239 {
240 integrity_dir = securityfs_create_dir("integrity", NULL);
241 if (IS_ERR(integrity_dir)) {
242 int ret = PTR_ERR(integrity_dir);
243
244 if (ret != -ENODEV)
245 pr_err("Unable to create integrity sysfs dir: %d\n",
246 ret);
247 integrity_dir = NULL;
248 return ret;
249 }
250
251 return 0;
252 }
253
254 late_initcall(integrity_fs_init)
255