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 iint = integrity_iint_find(inode);
102 if (iint)
103 return iint;
104
105 iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
106 if (!iint)
107 return NULL;
108
109 write_lock(&integrity_iint_lock);
110
111 p = &integrity_iint_tree.rb_node;
112 while (*p) {
113 parent = *p;
114 test_iint = rb_entry(parent, struct integrity_iint_cache,
115 rb_node);
116 if (inode < test_iint->inode)
117 p = &(*p)->rb_left;
118 else
119 p = &(*p)->rb_right;
120 }
121
122 iint->inode = inode;
123 node = &iint->rb_node;
124 inode->i_flags |= S_IMA;
125 rb_link_node(node, parent, p);
126 rb_insert_color(node, &integrity_iint_tree);
127
128 write_unlock(&integrity_iint_lock);
129 return iint;
130 }
131
132 /**
133 * integrity_inode_free - called on security_inode_free
134 * @inode: pointer to the inode
135 *
136 * Free the integrity information(iint) associated with an inode.
137 */
integrity_inode_free(struct inode * inode)138 void integrity_inode_free(struct inode *inode)
139 {
140 struct integrity_iint_cache *iint;
141
142 if (!IS_IMA(inode))
143 return;
144
145 write_lock(&integrity_iint_lock);
146 iint = __integrity_iint_find(inode);
147 rb_erase(&iint->rb_node, &integrity_iint_tree);
148 write_unlock(&integrity_iint_lock);
149
150 iint_free(iint);
151 }
152
init_once(void * foo)153 static void init_once(void *foo)
154 {
155 struct integrity_iint_cache *iint = foo;
156
157 memset(iint, 0, sizeof(*iint));
158 iint->ima_file_status = INTEGRITY_UNKNOWN;
159 iint->ima_mmap_status = INTEGRITY_UNKNOWN;
160 iint->ima_bprm_status = INTEGRITY_UNKNOWN;
161 iint->ima_read_status = INTEGRITY_UNKNOWN;
162 iint->ima_creds_status = INTEGRITY_UNKNOWN;
163 iint->evm_status = INTEGRITY_UNKNOWN;
164 mutex_init(&iint->mutex);
165 }
166
integrity_iintcache_init(void)167 static int __init integrity_iintcache_init(void)
168 {
169 iint_cache =
170 kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
171 0, SLAB_PANIC, init_once);
172 return 0;
173 }
174 DEFINE_LSM(integrity) = {
175 .name = "integrity",
176 .init = integrity_iintcache_init,
177 };
178
179
180 /*
181 * integrity_kernel_read - read data from the file
182 *
183 * This is a function for reading file content instead of kernel_read().
184 * It does not perform locking checks to ensure it cannot be blocked.
185 * It does not perform security checks because it is irrelevant for IMA.
186 *
187 */
integrity_kernel_read(struct file * file,loff_t offset,void * addr,unsigned long count)188 int integrity_kernel_read(struct file *file, loff_t offset,
189 void *addr, unsigned long count)
190 {
191 mm_segment_t old_fs;
192 char __user *buf = (char __user *)addr;
193 ssize_t ret;
194
195 if (!(file->f_mode & FMODE_READ))
196 return -EBADF;
197
198 old_fs = get_fs();
199 set_fs(KERNEL_DS);
200 ret = __vfs_read(file, buf, count, &offset);
201 set_fs(old_fs);
202
203 return ret;
204 }
205
206 /*
207 * integrity_load_keys - load integrity keys hook
208 *
209 * Hooks is called from init/main.c:kernel_init_freeable()
210 * when rootfs is ready
211 */
integrity_load_keys(void)212 void __init integrity_load_keys(void)
213 {
214 ima_load_x509();
215 evm_load_x509();
216 }
217
integrity_fs_init(void)218 static int __init integrity_fs_init(void)
219 {
220 integrity_dir = securityfs_create_dir("integrity", NULL);
221 if (IS_ERR(integrity_dir)) {
222 int ret = PTR_ERR(integrity_dir);
223
224 if (ret != -ENODEV)
225 pr_err("Unable to create integrity sysfs dir: %d\n",
226 ret);
227 integrity_dir = NULL;
228 return ret;
229 }
230
231 return 0;
232 }
233
234 late_initcall(integrity_fs_init)
235
