LSM: bury struct security_mnt_opts
[muen/linux.git] / security / integrity / iint.c
1 /*
2  * Copyright (C) 2008 IBM Corporation
3  *
4  * Authors:
5  * Mimi Zohar <zohar@us.ibm.com>
6  *
7  * This program is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU General Public License as
9  * published by the Free Software Foundation, version 2 of the
10  * License.
11  *
12  * File: integrity_iint.c
13  *      - implements the integrity hooks: integrity_inode_alloc,
14  *        integrity_inode_free
15  *      - cache integrity information associated with an inode
16  *        using a rbtree tree.
17  */
18 #include <linux/slab.h>
19 #include <linux/module.h>
20 #include <linux/spinlock.h>
21 #include <linux/rbtree.h>
22 #include <linux/file.h>
23 #include <linux/uaccess.h>
24 #include <linux/security.h>
25 #include <linux/lsm_hooks.h>
26 #include "integrity.h"
27
28 static struct rb_root integrity_iint_tree = RB_ROOT;
29 static DEFINE_RWLOCK(integrity_iint_lock);
30 static struct kmem_cache *iint_cache __read_mostly;
31
32 struct dentry *integrity_dir;
33
34 /*
35  * __integrity_iint_find - return the iint associated with an inode
36  */
37 static struct integrity_iint_cache *__integrity_iint_find(struct inode *inode)
38 {
39         struct integrity_iint_cache *iint;
40         struct rb_node *n = integrity_iint_tree.rb_node;
41
42         while (n) {
43                 iint = rb_entry(n, struct integrity_iint_cache, rb_node);
44
45                 if (inode < iint->inode)
46                         n = n->rb_left;
47                 else if (inode > iint->inode)
48                         n = n->rb_right;
49                 else
50                         break;
51         }
52         if (!n)
53                 return NULL;
54
55         return iint;
56 }
57
58 /*
59  * integrity_iint_find - return the iint associated with an inode
60  */
61 struct integrity_iint_cache *integrity_iint_find(struct inode *inode)
62 {
63         struct integrity_iint_cache *iint;
64
65         if (!IS_IMA(inode))
66                 return NULL;
67
68         read_lock(&integrity_iint_lock);
69         iint = __integrity_iint_find(inode);
70         read_unlock(&integrity_iint_lock);
71
72         return iint;
73 }
74
75 static void iint_free(struct integrity_iint_cache *iint)
76 {
77         kfree(iint->ima_hash);
78         iint->ima_hash = NULL;
79         iint->version = 0;
80         iint->flags = 0UL;
81         iint->atomic_flags = 0UL;
82         iint->ima_file_status = INTEGRITY_UNKNOWN;
83         iint->ima_mmap_status = INTEGRITY_UNKNOWN;
84         iint->ima_bprm_status = INTEGRITY_UNKNOWN;
85         iint->ima_read_status = INTEGRITY_UNKNOWN;
86         iint->ima_creds_status = INTEGRITY_UNKNOWN;
87         iint->evm_status = INTEGRITY_UNKNOWN;
88         iint->measured_pcrs = 0;
89         kmem_cache_free(iint_cache, iint);
90 }
91
92 /**
93  * integrity_inode_get - find or allocate an iint associated with an inode
94  * @inode: pointer to the inode
95  * @return: allocated iint
96  *
97  * Caller must lock i_mutex
98  */
99 struct integrity_iint_cache *integrity_inode_get(struct inode *inode)
100 {
101         struct rb_node **p;
102         struct rb_node *node, *parent = NULL;
103         struct integrity_iint_cache *iint, *test_iint;
104
105         iint = integrity_iint_find(inode);
106         if (iint)
107                 return iint;
108
109         iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
110         if (!iint)
111                 return NULL;
112
113         write_lock(&integrity_iint_lock);
114
115         p = &integrity_iint_tree.rb_node;
116         while (*p) {
117                 parent = *p;
118                 test_iint = rb_entry(parent, struct integrity_iint_cache,
119                                      rb_node);
120                 if (inode < test_iint->inode)
121                         p = &(*p)->rb_left;
122                 else
123                         p = &(*p)->rb_right;
124         }
125
126         iint->inode = inode;
127         node = &iint->rb_node;
128         inode->i_flags |= S_IMA;
129         rb_link_node(node, parent, p);
130         rb_insert_color(node, &integrity_iint_tree);
131
132         write_unlock(&integrity_iint_lock);
133         return iint;
134 }
135
136 /**
137  * integrity_inode_free - called on security_inode_free
138  * @inode: pointer to the inode
139  *
140  * Free the integrity information(iint) associated with an inode.
141  */
142 void integrity_inode_free(struct inode *inode)
143 {
144         struct integrity_iint_cache *iint;
145
146         if (!IS_IMA(inode))
147                 return;
148
149         write_lock(&integrity_iint_lock);
150         iint = __integrity_iint_find(inode);
151         rb_erase(&iint->rb_node, &integrity_iint_tree);
152         write_unlock(&integrity_iint_lock);
153
154         iint_free(iint);
155 }
156
157 static void init_once(void *foo)
158 {
159         struct integrity_iint_cache *iint = foo;
160
161         memset(iint, 0, sizeof(*iint));
162         iint->ima_file_status = INTEGRITY_UNKNOWN;
163         iint->ima_mmap_status = INTEGRITY_UNKNOWN;
164         iint->ima_bprm_status = INTEGRITY_UNKNOWN;
165         iint->ima_read_status = INTEGRITY_UNKNOWN;
166         iint->ima_creds_status = INTEGRITY_UNKNOWN;
167         iint->evm_status = INTEGRITY_UNKNOWN;
168         mutex_init(&iint->mutex);
169 }
170
171 static int __init integrity_iintcache_init(void)
172 {
173         iint_cache =
174             kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
175                               0, SLAB_PANIC, init_once);
176         return 0;
177 }
178 DEFINE_LSM(integrity) = {
179         .name = "integrity",
180         .init = integrity_iintcache_init,
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  */
192 int integrity_kernel_read(struct file *file, loff_t offset,
193                           void *addr, unsigned long count)
194 {
195         mm_segment_t old_fs;
196         char __user *buf = (char __user *)addr;
197         ssize_t ret;
198
199         if (!(file->f_mode & FMODE_READ))
200                 return -EBADF;
201
202         old_fs = get_fs();
203         set_fs(get_ds());
204         ret = __vfs_read(file, buf, count, &offset);
205         set_fs(old_fs);
206
207         return ret;
208 }
209
210 /*
211  * integrity_load_keys - load integrity keys hook
212  *
213  * Hooks is called from init/main.c:kernel_init_freeable()
214  * when rootfs is ready
215  */
216 void __init integrity_load_keys(void)
217 {
218         ima_load_x509();
219         evm_load_x509();
220 }
221
222 static int __init integrity_fs_init(void)
223 {
224         integrity_dir = securityfs_create_dir("integrity", NULL);
225         if (IS_ERR(integrity_dir)) {
226                 int ret = PTR_ERR(integrity_dir);
227
228                 if (ret != -ENODEV)
229                         pr_err("Unable to create integrity sysfs dir: %d\n",
230                                ret);
231                 integrity_dir = NULL;
232                 return ret;
233         }
234
235         return 0;
236 }
237
238 late_initcall(integrity_fs_init)