1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
|
/*
* Encryption policy functions for per-file encryption support.
*
* Copyright (C) 2015, Google, Inc.
* Copyright (C) 2015, Motorola Mobility.
*
* Written by Michael Halcrow, 2015.
* Modified by Jaegeuk Kim, 2015.
*/
#include <linux/random.h>
#include <linux/string.h>
#include <linux/mount.h>
#include "fscrypt_private.h"
static int inode_has_encryption_context(struct inode *inode)
{
if (!inode->i_sb->s_cop->get_context)
return 0;
return (inode->i_sb->s_cop->get_context(inode, NULL, 0L) > 0);
}
/*
* check whether the policy is consistent with the encryption context
* for the inode
*/
static int is_encryption_context_consistent_with_policy(struct inode *inode,
const struct fscrypt_policy *policy)
{
struct fscrypt_context ctx;
int res;
if (!inode->i_sb->s_cop->get_context)
return 0;
res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
if (res != sizeof(ctx))
return 0;
return (memcmp(ctx.master_key_descriptor, policy->master_key_descriptor,
FS_KEY_DESCRIPTOR_SIZE) == 0 &&
(ctx.flags == policy->flags) &&
(ctx.contents_encryption_mode ==
policy->contents_encryption_mode) &&
(ctx.filenames_encryption_mode ==
policy->filenames_encryption_mode));
}
static int create_encryption_context_from_policy(struct inode *inode,
const struct fscrypt_policy *policy)
{
struct fscrypt_context ctx;
int res;
if (!inode->i_sb->s_cop->set_context)
return -EOPNOTSUPP;
if (inode->i_sb->s_cop->prepare_context) {
res = inode->i_sb->s_cop->prepare_context(inode);
if (res)
return res;
}
ctx.format = FS_ENCRYPTION_CONTEXT_FORMAT_V1;
memcpy(ctx.master_key_descriptor, policy->master_key_descriptor,
FS_KEY_DESCRIPTOR_SIZE);
if (!fscrypt_valid_contents_enc_mode(
policy->contents_encryption_mode))
return -EINVAL;
if (!fscrypt_valid_filenames_enc_mode(
policy->filenames_encryption_mode))
return -EINVAL;
if (policy->flags & ~FS_POLICY_FLAGS_VALID)
return -EINVAL;
ctx.contents_encryption_mode = policy->contents_encryption_mode;
ctx.filenames_encryption_mode = policy->filenames_encryption_mode;
ctx.flags = policy->flags;
BUILD_BUG_ON(sizeof(ctx.nonce) != FS_KEY_DERIVATION_NONCE_SIZE);
get_random_bytes(ctx.nonce, FS_KEY_DERIVATION_NONCE_SIZE);
return inode->i_sb->s_cop->set_context(inode, &ctx, sizeof(ctx), NULL);
}
int fscrypt_ioctl_set_policy(struct file *filp, const void __user *arg)
{
struct fscrypt_policy policy;
struct inode *inode = file_inode(filp);
int ret;
if (copy_from_user(&policy, arg, sizeof(policy)))
return -EFAULT;
if (!inode_owner_or_capable(inode))
return -EACCES;
if (policy.version != 0)
return -EINVAL;
ret = mnt_want_write_file(filp);
if (ret)
return ret;
inode_lock(inode);
if (!inode_has_encryption_context(inode)) {
if (!S_ISDIR(inode->i_mode))
ret = -ENOTDIR;
else if (!inode->i_sb->s_cop->empty_dir)
ret = -EOPNOTSUPP;
else if (!inode->i_sb->s_cop->empty_dir(inode))
ret = -ENOTEMPTY;
else
ret = create_encryption_context_from_policy(inode,
&policy);
} else if (!is_encryption_context_consistent_with_policy(inode,
&policy)) {
ret = -EEXIST;
}
inode_unlock(inode);
mnt_drop_write_file(filp);
return ret;
}
EXPORT_SYMBOL(fscrypt_ioctl_set_policy);
int fscrypt_ioctl_get_policy(struct file *filp, void __user *arg)
{
struct inode *inode = file_inode(filp);
struct fscrypt_context ctx;
struct fscrypt_policy policy;
int res;
if (!inode->i_sb->s_cop->get_context ||
!inode->i_sb->s_cop->is_encrypted(inode))
return -ENODATA;
res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
if (res != sizeof(ctx))
return -ENODATA;
if (ctx.format != FS_ENCRYPTION_CONTEXT_FORMAT_V1)
return -EINVAL;
policy.version = 0;
policy.contents_encryption_mode = ctx.contents_encryption_mode;
policy.filenames_encryption_mode = ctx.filenames_encryption_mode;
policy.flags = ctx.flags;
memcpy(policy.master_key_descriptor, ctx.master_key_descriptor,
FS_KEY_DESCRIPTOR_SIZE);
if (copy_to_user(arg, &policy, sizeof(policy)))
return -EFAULT;
return 0;
}
EXPORT_SYMBOL(fscrypt_ioctl_get_policy);
int fscrypt_has_permitted_context(struct inode *parent, struct inode *child)
{
struct fscrypt_info *parent_ci, *child_ci;
int res;
if ((parent == NULL) || (child == NULL)) {
printk(KERN_ERR "parent %p child %p\n", parent, child);
BUG_ON(1);
}
/* No restrictions on file types which are never encrypted */
if (!S_ISREG(child->i_mode) && !S_ISDIR(child->i_mode) &&
!S_ISLNK(child->i_mode))
return 1;
/* no restrictions if the parent directory is not encrypted */
if (!parent->i_sb->s_cop->is_encrypted(parent))
return 1;
/* if the child directory is not encrypted, this is always a problem */
if (!parent->i_sb->s_cop->is_encrypted(child))
return 0;
res = fscrypt_get_encryption_info(parent);
if (res)
return 0;
res = fscrypt_get_encryption_info(child);
if (res)
return 0;
parent_ci = parent->i_crypt_info;
child_ci = child->i_crypt_info;
if (!parent_ci && !child_ci)
return 1;
if (!parent_ci || !child_ci)
return 0;
return (memcmp(parent_ci->ci_master_key,
child_ci->ci_master_key,
FS_KEY_DESCRIPTOR_SIZE) == 0 &&
(parent_ci->ci_data_mode == child_ci->ci_data_mode) &&
(parent_ci->ci_filename_mode == child_ci->ci_filename_mode) &&
(parent_ci->ci_flags == child_ci->ci_flags));
}
EXPORT_SYMBOL(fscrypt_has_permitted_context);
/**
* fscrypt_inherit_context() - Sets a child context from its parent
* @parent: Parent inode from which the context is inherited.
* @child: Child inode that inherits the context from @parent.
* @fs_data: private data given by FS.
* @preload: preload child i_crypt_info
*
* Return: Zero on success, non-zero otherwise
*/
int fscrypt_inherit_context(struct inode *parent, struct inode *child,
void *fs_data, bool preload)
{
struct fscrypt_context ctx;
struct fscrypt_info *ci;
int res;
if (!parent->i_sb->s_cop->set_context)
return -EOPNOTSUPP;
res = fscrypt_get_encryption_info(parent);
if (res < 0)
return res;
ci = parent->i_crypt_info;
if (ci == NULL)
return -ENOKEY;
ctx.format = FS_ENCRYPTION_CONTEXT_FORMAT_V1;
if (fscrypt_dummy_context_enabled(parent)) {
ctx.contents_encryption_mode = FS_ENCRYPTION_MODE_AES_256_XTS;
ctx.filenames_encryption_mode = FS_ENCRYPTION_MODE_AES_256_CTS;
ctx.flags = 0;
memset(ctx.master_key_descriptor, 0x42, FS_KEY_DESCRIPTOR_SIZE);
res = 0;
} else {
ctx.contents_encryption_mode = ci->ci_data_mode;
ctx.filenames_encryption_mode = ci->ci_filename_mode;
ctx.flags = ci->ci_flags;
memcpy(ctx.master_key_descriptor, ci->ci_master_key,
FS_KEY_DESCRIPTOR_SIZE);
}
get_random_bytes(ctx.nonce, FS_KEY_DERIVATION_NONCE_SIZE);
res = parent->i_sb->s_cop->set_context(child, &ctx,
sizeof(ctx), fs_data);
if (res)
return res;
return preload ? fscrypt_get_encryption_info(child): 0;
}
EXPORT_SYMBOL(fscrypt_inherit_context);
|
