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
|
/*
* linux/fs/ext4/crypto_policy.c
*
* Copyright (C) 2015, Google, Inc.
*
* This contains encryption policy functions for ext4
*
* Written by Michael Halcrow, 2015.
*/
#include <linux/random.h>
#include <linux/string.h>
#include <linux/types.h>
#include "ext4_jbd2.h"
#include "ext4.h"
#include "xattr.h"
static int ext4_inode_has_encryption_context(struct inode *inode)
{
int res = ext4_xattr_get(inode, EXT4_XATTR_INDEX_ENCRYPTION,
EXT4_XATTR_NAME_ENCRYPTION_CONTEXT, NULL, 0);
return (res > 0);
}
/*
* check whether the policy is consistent with the encryption context
* for the inode
*/
static int ext4_is_encryption_context_consistent_with_policy(
struct inode *inode, const struct ext4_encryption_policy *policy)
{
struct ext4_encryption_context ctx;
int res = ext4_xattr_get(inode, EXT4_XATTR_INDEX_ENCRYPTION,
EXT4_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx,
sizeof(ctx));
if (res != sizeof(ctx))
return 0;
return (memcmp(ctx.master_key_descriptor, policy->master_key_descriptor,
EXT4_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 ext4_create_encryption_context_from_policy(
struct inode *inode, const struct ext4_encryption_policy *policy)
{
struct ext4_encryption_context ctx;
handle_t *handle;
int res, res2;
res = ext4_convert_inline_data(inode);
if (res)
return res;
ctx.format = EXT4_ENCRYPTION_CONTEXT_FORMAT_V1;
memcpy(ctx.master_key_descriptor, policy->master_key_descriptor,
EXT4_KEY_DESCRIPTOR_SIZE);
if (!ext4_valid_contents_enc_mode(policy->contents_encryption_mode)) {
printk(KERN_WARNING
"%s: Invalid contents encryption mode %d\n", __func__,
policy->contents_encryption_mode);
return -EINVAL;
}
if (!ext4_valid_filenames_enc_mode(policy->filenames_encryption_mode)) {
printk(KERN_WARNING
"%s: Invalid filenames encryption mode %d\n", __func__,
policy->filenames_encryption_mode);
return -EINVAL;
}
if (policy->flags & ~EXT4_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) != EXT4_KEY_DERIVATION_NONCE_SIZE);
get_random_bytes(ctx.nonce, EXT4_KEY_DERIVATION_NONCE_SIZE);
handle = ext4_journal_start(inode, EXT4_HT_MISC,
ext4_jbd2_credits_xattr(inode));
if (IS_ERR(handle))
return PTR_ERR(handle);
res = ext4_xattr_set(inode, EXT4_XATTR_INDEX_ENCRYPTION,
EXT4_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx,
sizeof(ctx), 0);
if (!res) {
ext4_set_inode_flag(inode, EXT4_INODE_ENCRYPT);
res = ext4_mark_inode_dirty(handle, inode);
if (res)
EXT4_ERROR_INODE(inode, "Failed to mark inode dirty");
}
res2 = ext4_journal_stop(handle);
if (!res)
res = res2;
return res;
}
int ext4_process_policy(const struct ext4_encryption_policy *policy,
struct inode *inode)
{
if (policy->version != 0)
return -EINVAL;
if (!ext4_inode_has_encryption_context(inode)) {
if (!S_ISDIR(inode->i_mode))
return -EINVAL;
if (!ext4_empty_dir(inode))
return -ENOTEMPTY;
return ext4_create_encryption_context_from_policy(inode,
policy);
}
if (ext4_is_encryption_context_consistent_with_policy(inode, policy))
return 0;
printk(KERN_WARNING "%s: Policy inconsistent with encryption context\n",
__func__);
return -EINVAL;
}
int ext4_get_policy(struct inode *inode, struct ext4_encryption_policy *policy)
{
struct ext4_encryption_context ctx;
int res = ext4_xattr_get(inode, EXT4_XATTR_INDEX_ENCRYPTION,
EXT4_XATTR_NAME_ENCRYPTION_CONTEXT,
&ctx, sizeof(ctx));
if (res != sizeof(ctx))
return -ENOENT;
if (ctx.format != EXT4_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,
EXT4_KEY_DESCRIPTOR_SIZE);
return 0;
}
int ext4_is_child_context_consistent_with_parent(struct inode *parent,
struct inode *child)
{
struct ext4_crypt_info *parent_ci, *child_ci;
int res;
if ((parent == NULL) || (child == NULL)) {
pr_err("parent %p child %p\n", parent, child);
WARN_ON(1); /* Should never happen */
return 0;
}
/* no restrictions if the parent directory is not encrypted */
if (!ext4_encrypted_inode(parent))
return 1;
/* if the child directory is not encrypted, this is always a problem */
if (!ext4_encrypted_inode(child))
return 0;
res = ext4_get_encryption_info(parent);
if (res)
return 0;
res = ext4_get_encryption_info(child);
if (res)
return 0;
parent_ci = EXT4_I(parent)->i_crypt_info;
child_ci = EXT4_I(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,
EXT4_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));
}
/**
* ext4_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.
*
* Return: Zero on success, non-zero otherwise
*/
int ext4_inherit_context(struct inode *parent, struct inode *child)
{
struct ext4_encryption_context ctx;
struct ext4_crypt_info *ci;
int res;
res = ext4_get_encryption_info(parent);
if (res < 0)
return res;
ci = EXT4_I(parent)->i_crypt_info;
if (ci == NULL)
return -ENOKEY;
ctx.format = EXT4_ENCRYPTION_CONTEXT_FORMAT_V1;
if (DUMMY_ENCRYPTION_ENABLED(EXT4_SB(parent->i_sb))) {
ctx.contents_encryption_mode = EXT4_ENCRYPTION_MODE_AES_256_XTS;
ctx.filenames_encryption_mode =
EXT4_ENCRYPTION_MODE_AES_256_CTS;
ctx.flags = 0;
memset(ctx.master_key_descriptor, 0x42,
EXT4_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,
EXT4_KEY_DESCRIPTOR_SIZE);
}
get_random_bytes(ctx.nonce, EXT4_KEY_DERIVATION_NONCE_SIZE);
res = ext4_xattr_set(child, EXT4_XATTR_INDEX_ENCRYPTION,
EXT4_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx,
sizeof(ctx), 0);
if (!res) {
ext4_set_inode_flag(child, EXT4_INODE_ENCRYPT);
ext4_clear_inode_state(child, EXT4_STATE_MAY_INLINE_DATA);
res = ext4_get_encryption_info(child);
}
return res;
}
|
