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f424f664 JK |
1 | /* |
2 | * copied from linux/fs/ext4/crypto_policy.c | |
3 | * | |
4 | * Copyright (C) 2015, Google, Inc. | |
5 | * Copyright (C) 2015, Motorola Mobility. | |
6 | * | |
7 | * This contains encryption policy functions for f2fs with some modifications | |
8 | * to support f2fs-specific xattr APIs. | |
9 | * | |
10 | * Written by Michael Halcrow, 2015. | |
11 | * Modified by Jaegeuk Kim, 2015. | |
12 | */ | |
13 | #include <linux/random.h> | |
14 | #include <linux/string.h> | |
15 | #include <linux/types.h> | |
16 | #include <linux/f2fs_fs.h> | |
17 | ||
18 | #include "f2fs.h" | |
19 | #include "xattr.h" | |
20 | ||
21 | static int f2fs_inode_has_encryption_context(struct inode *inode) | |
22 | { | |
23 | int res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION, | |
24 | F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, NULL, 0, NULL); | |
25 | return (res > 0); | |
26 | } | |
27 | ||
28 | /* | |
29 | * check whether the policy is consistent with the encryption context | |
30 | * for the inode | |
31 | */ | |
32 | static int f2fs_is_encryption_context_consistent_with_policy( | |
33 | struct inode *inode, const struct f2fs_encryption_policy *policy) | |
34 | { | |
35 | struct f2fs_encryption_context ctx; | |
36 | int res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION, | |
37 | F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx, | |
38 | sizeof(ctx), NULL); | |
39 | ||
40 | if (res != sizeof(ctx)) | |
41 | return 0; | |
42 | ||
43 | return (memcmp(ctx.master_key_descriptor, policy->master_key_descriptor, | |
44 | F2FS_KEY_DESCRIPTOR_SIZE) == 0 && | |
45 | (ctx.flags == policy->flags) && | |
46 | (ctx.contents_encryption_mode == | |
47 | policy->contents_encryption_mode) && | |
48 | (ctx.filenames_encryption_mode == | |
49 | policy->filenames_encryption_mode)); | |
50 | } | |
51 | ||
52 | static int f2fs_create_encryption_context_from_policy( | |
53 | struct inode *inode, const struct f2fs_encryption_policy *policy) | |
54 | { | |
55 | struct f2fs_encryption_context ctx; | |
56 | ||
57 | ctx.format = F2FS_ENCRYPTION_CONTEXT_FORMAT_V1; | |
58 | memcpy(ctx.master_key_descriptor, policy->master_key_descriptor, | |
59 | F2FS_KEY_DESCRIPTOR_SIZE); | |
60 | ||
61 | if (!f2fs_valid_contents_enc_mode(policy->contents_encryption_mode)) { | |
62 | printk(KERN_WARNING | |
63 | "%s: Invalid contents encryption mode %d\n", __func__, | |
64 | policy->contents_encryption_mode); | |
65 | return -EINVAL; | |
66 | } | |
67 | ||
68 | if (!f2fs_valid_filenames_enc_mode(policy->filenames_encryption_mode)) { | |
69 | printk(KERN_WARNING | |
70 | "%s: Invalid filenames encryption mode %d\n", __func__, | |
71 | policy->filenames_encryption_mode); | |
72 | return -EINVAL; | |
73 | } | |
74 | ||
75 | if (policy->flags & ~F2FS_POLICY_FLAGS_VALID) | |
76 | return -EINVAL; | |
77 | ||
78 | ctx.contents_encryption_mode = policy->contents_encryption_mode; | |
79 | ctx.filenames_encryption_mode = policy->filenames_encryption_mode; | |
80 | ctx.flags = policy->flags; | |
81 | BUILD_BUG_ON(sizeof(ctx.nonce) != F2FS_KEY_DERIVATION_NONCE_SIZE); | |
82 | get_random_bytes(ctx.nonce, F2FS_KEY_DERIVATION_NONCE_SIZE); | |
83 | ||
84 | return f2fs_setxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION, | |
85 | F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx, | |
81b0a8ff | 86 | sizeof(ctx), NULL, XATTR_CREATE); |
f424f664 JK |
87 | } |
88 | ||
89 | int f2fs_process_policy(const struct f2fs_encryption_policy *policy, | |
90 | struct inode *inode) | |
91 | { | |
92 | if (policy->version != 0) | |
93 | return -EINVAL; | |
94 | ||
4637fd11 CY |
95 | if (!S_ISDIR(inode->i_mode)) |
96 | return -EINVAL; | |
97 | ||
f424f664 JK |
98 | if (!f2fs_inode_has_encryption_context(inode)) { |
99 | if (!f2fs_empty_dir(inode)) | |
100 | return -ENOTEMPTY; | |
101 | return f2fs_create_encryption_context_from_policy(inode, | |
102 | policy); | |
103 | } | |
104 | ||
105 | if (f2fs_is_encryption_context_consistent_with_policy(inode, policy)) | |
106 | return 0; | |
107 | ||
108 | printk(KERN_WARNING "%s: Policy inconsistent with encryption context\n", | |
109 | __func__); | |
110 | return -EINVAL; | |
111 | } | |
112 | ||
113 | int f2fs_get_policy(struct inode *inode, struct f2fs_encryption_policy *policy) | |
114 | { | |
115 | struct f2fs_encryption_context ctx; | |
116 | int res; | |
117 | ||
118 | if (!f2fs_encrypted_inode(inode)) | |
119 | return -ENODATA; | |
120 | ||
121 | res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION, | |
122 | F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, | |
123 | &ctx, sizeof(ctx), NULL); | |
124 | if (res != sizeof(ctx)) | |
125 | return -ENODATA; | |
126 | if (ctx.format != F2FS_ENCRYPTION_CONTEXT_FORMAT_V1) | |
127 | return -EINVAL; | |
128 | ||
129 | policy->version = 0; | |
130 | policy->contents_encryption_mode = ctx.contents_encryption_mode; | |
131 | policy->filenames_encryption_mode = ctx.filenames_encryption_mode; | |
132 | policy->flags = ctx.flags; | |
133 | memcpy(&policy->master_key_descriptor, ctx.master_key_descriptor, | |
134 | F2FS_KEY_DESCRIPTOR_SIZE); | |
135 | return 0; | |
136 | } | |
137 | ||
138 | int f2fs_is_child_context_consistent_with_parent(struct inode *parent, | |
139 | struct inode *child) | |
140 | { | |
141 | struct f2fs_crypt_info *parent_ci, *child_ci; | |
142 | int res; | |
143 | ||
144 | if ((parent == NULL) || (child == NULL)) { | |
145 | pr_err("parent %p child %p\n", parent, child); | |
146 | BUG_ON(1); | |
147 | } | |
148 | ||
149 | /* no restrictions if the parent directory is not encrypted */ | |
150 | if (!f2fs_encrypted_inode(parent)) | |
151 | return 1; | |
152 | /* if the child directory is not encrypted, this is always a problem */ | |
153 | if (!f2fs_encrypted_inode(child)) | |
154 | return 0; | |
155 | res = f2fs_get_encryption_info(parent); | |
156 | if (res) | |
157 | return 0; | |
158 | res = f2fs_get_encryption_info(child); | |
159 | if (res) | |
160 | return 0; | |
161 | parent_ci = F2FS_I(parent)->i_crypt_info; | |
162 | child_ci = F2FS_I(child)->i_crypt_info; | |
163 | if (!parent_ci && !child_ci) | |
164 | return 1; | |
165 | if (!parent_ci || !child_ci) | |
166 | return 0; | |
167 | ||
168 | return (memcmp(parent_ci->ci_master_key, | |
169 | child_ci->ci_master_key, | |
170 | F2FS_KEY_DESCRIPTOR_SIZE) == 0 && | |
171 | (parent_ci->ci_data_mode == child_ci->ci_data_mode) && | |
172 | (parent_ci->ci_filename_mode == child_ci->ci_filename_mode) && | |
173 | (parent_ci->ci_flags == child_ci->ci_flags)); | |
174 | } | |
175 | ||
176 | /** | |
177 | * f2fs_inherit_context() - Sets a child context from its parent | |
178 | * @parent: Parent inode from which the context is inherited. | |
179 | * @child: Child inode that inherits the context from @parent. | |
180 | * | |
181 | * Return: Zero on success, non-zero otherwise | |
182 | */ | |
183 | int f2fs_inherit_context(struct inode *parent, struct inode *child, | |
184 | struct page *ipage) | |
185 | { | |
186 | struct f2fs_encryption_context ctx; | |
187 | struct f2fs_crypt_info *ci; | |
188 | int res; | |
189 | ||
190 | res = f2fs_get_encryption_info(parent); | |
191 | if (res < 0) | |
192 | return res; | |
193 | ||
194 | ci = F2FS_I(parent)->i_crypt_info; | |
195 | BUG_ON(ci == NULL); | |
196 | ||
197 | ctx.format = F2FS_ENCRYPTION_CONTEXT_FORMAT_V1; | |
198 | ||
199 | ctx.contents_encryption_mode = ci->ci_data_mode; | |
200 | ctx.filenames_encryption_mode = ci->ci_filename_mode; | |
201 | ctx.flags = ci->ci_flags; | |
202 | memcpy(ctx.master_key_descriptor, ci->ci_master_key, | |
203 | F2FS_KEY_DESCRIPTOR_SIZE); | |
204 | ||
205 | get_random_bytes(ctx.nonce, F2FS_KEY_DERIVATION_NONCE_SIZE); | |
206 | return f2fs_setxattr(child, F2FS_XATTR_INDEX_ENCRYPTION, | |
207 | F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx, | |
81b0a8ff | 208 | sizeof(ctx), ipage, XATTR_CREATE); |
f424f664 | 209 | } |