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 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->ima_creds_status = INTEGRITY_UNKNOWN;
83 iint->evm_status = INTEGRITY_UNKNOWN;
84 iint->measured_pcrs = 0;
85 kmem_cache_free(iint_cache, iint);
86 }
87
88 /**
89 * integrity_inode_get - find or allocate an iint associated with an inode
90 * @inode: pointer to the inode
91 * @return: allocated iint
92 *
93 * Caller must lock i_mutex
94 */
integrity_inode_get(struct inode * inode)95 struct integrity_iint_cache *integrity_inode_get(struct inode *inode)
96 {
97 struct rb_node **p;
98 struct rb_node *node, *parent = NULL;
99 struct integrity_iint_cache *iint, *test_iint;
100
101 /*
102 * The integrity's "iint_cache" is initialized at security_init(),
103 * unless it is not included in the ordered list of LSMs enabled
104 * on the boot command line.
105 */
106 if (!iint_cache)
107 panic("%s: lsm=integrity required.\n", __func__);
108
109 iint = integrity_iint_find(inode);
110 if (iint)
111 return iint;
112
113 iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
114 if (!iint)
115 return NULL;
116
117 write_lock(&integrity_iint_lock);
118
119 p = &integrity_iint_tree.rb_node;
120 while (*p) {
121 parent = *p;
122 test_iint = rb_entry(parent, struct integrity_iint_cache,
123 rb_node);
124 if (inode < test_iint->inode)
125 p = &(*p)->rb_left;
126 else
127 p = &(*p)->rb_right;
128 }
129
130 iint->inode = inode;
131 node = &iint->rb_node;
132 inode->i_flags |= S_IMA;
133 rb_link_node(node, parent, p);
134 rb_insert_color(node, &integrity_iint_tree);
135
136 write_unlock(&integrity_iint_lock);
137 return iint;
138 }
139
140 /**
141 * integrity_inode_free - called on security_inode_free
142 * @inode: pointer to the inode
143 *
144 * Free the integrity information(iint) associated with an inode.
145 */
integrity_inode_free(struct inode * inode)146 void integrity_inode_free(struct inode *inode)
147 {
148 struct integrity_iint_cache *iint;
149
150 if (!IS_IMA(inode))
151 return;
152
153 write_lock(&integrity_iint_lock);
154 iint = __integrity_iint_find(inode);
155 rb_erase(&iint->rb_node, &integrity_iint_tree);
156 write_unlock(&integrity_iint_lock);
157
158 iint_free(iint);
159 }
160
init_once(void * foo)161 static void init_once(void *foo)
162 {
163 struct integrity_iint_cache *iint = (struct integrity_iint_cache *) foo;
164
165 memset(iint, 0, sizeof(*iint));
166 iint->ima_file_status = INTEGRITY_UNKNOWN;
167 iint->ima_mmap_status = INTEGRITY_UNKNOWN;
168 iint->ima_bprm_status = INTEGRITY_UNKNOWN;
169 iint->ima_read_status = INTEGRITY_UNKNOWN;
170 iint->ima_creds_status = INTEGRITY_UNKNOWN;
171 iint->evm_status = INTEGRITY_UNKNOWN;
172 mutex_init(&iint->mutex);
173 }
174
integrity_iintcache_init(void)175 static int __init integrity_iintcache_init(void)
176 {
177 iint_cache =
178 kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
179 0, SLAB_PANIC, init_once);
180 return 0;
181 }
182 DEFINE_LSM(integrity) = {
183 .name = "integrity",
184 .init = integrity_iintcache_init,
185 };
186
187
188 /*
189 * integrity_kernel_read - read data from the file
190 *
191 * This is a function for reading file content instead of kernel_read().
192 * It does not perform locking checks to ensure it cannot be blocked.
193 * It does not perform security checks because it is irrelevant for IMA.
194 *
195 */
integrity_kernel_read(struct file * file,loff_t offset,void * addr,unsigned long count)196 int integrity_kernel_read(struct file *file, loff_t offset,
197 void *addr, unsigned long count)
198 {
199 return __kernel_read(file, addr, count, &offset);
200 }
201
202 /*
203 * integrity_load_keys - load integrity keys hook
204 *
205 * Hooks is called from init/main.c:kernel_init_freeable()
206 * when rootfs is ready
207 */
integrity_load_keys(void)208 void __init integrity_load_keys(void)
209 {
210 ima_load_x509();
211
212 if (!IS_ENABLED(CONFIG_IMA_LOAD_X509))
213 evm_load_x509();
214 }
215
integrity_fs_init(void)216 static int __init integrity_fs_init(void)
217 {
218 integrity_dir = securityfs_create_dir("integrity", NULL);
219 if (IS_ERR(integrity_dir)) {
220 int ret = PTR_ERR(integrity_dir);
221
222 if (ret != -ENODEV)
223 pr_err("Unable to create integrity sysfs dir: %d\n",
224 ret);
225 integrity_dir = NULL;
226 return ret;
227 }
228
229 return 0;
230 }
231
232 late_initcall(integrity_fs_init)
233