Merge tag 'docs-5.12-2' of git://git.lwn.net/linux
[sfrench/cifs-2.6.git] / security / integrity / iint.c
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  */
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  */
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
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  */
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  */
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
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
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  */
188 int integrity_kernel_read(struct file *file, loff_t offset,
189                           void *addr, unsigned long count)
190 {
191         return __kernel_read(file, addr, count, &offset);
192 }
193
194 /*
195  * integrity_load_keys - load integrity keys hook
196  *
197  * Hooks is called from init/main.c:kernel_init_freeable()
198  * when rootfs is ready
199  */
200 void __init integrity_load_keys(void)
201 {
202         ima_load_x509();
203         evm_load_x509();
204 }
205
206 static int __init integrity_fs_init(void)
207 {
208         integrity_dir = securityfs_create_dir("integrity", NULL);
209         if (IS_ERR(integrity_dir)) {
210                 int ret = PTR_ERR(integrity_dir);
211
212                 if (ret != -ENODEV)
213                         pr_err("Unable to create integrity sysfs dir: %d\n",
214                                ret);
215                 integrity_dir = NULL;
216                 return ret;
217         }
218
219         return 0;
220 }
221
222 late_initcall(integrity_fs_init)