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0adda907 JK |
1 | /* |
2 | * linux/fs/f2fs/crypto_key.c | |
3 | * | |
4 | * Copied from linux/fs/f2fs/crypto_key.c | |
5 | * | |
6 | * Copyright (C) 2015, Google, Inc. | |
7 | * | |
8 | * This contains encryption key functions for f2fs | |
9 | * | |
10 | * Written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar, 2015. | |
11 | */ | |
12 | #include <keys/encrypted-type.h> | |
13 | #include <keys/user-type.h> | |
14 | #include <linux/random.h> | |
15 | #include <linux/scatterlist.h> | |
16 | #include <uapi/linux/keyctl.h> | |
17 | #include <crypto/hash.h> | |
18 | #include <linux/f2fs_fs.h> | |
19 | ||
20 | #include "f2fs.h" | |
21 | #include "xattr.h" | |
22 | ||
23 | static void derive_crypt_complete(struct crypto_async_request *req, int rc) | |
24 | { | |
25 | struct f2fs_completion_result *ecr = req->data; | |
26 | ||
27 | if (rc == -EINPROGRESS) | |
28 | return; | |
29 | ||
30 | ecr->res = rc; | |
31 | complete(&ecr->completion); | |
32 | } | |
33 | ||
34 | /** | |
35 | * f2fs_derive_key_aes() - Derive a key using AES-128-ECB | |
36 | * @deriving_key: Encryption key used for derivatio. | |
37 | * @source_key: Source key to which to apply derivation. | |
38 | * @derived_key: Derived key. | |
39 | * | |
40 | * Return: Zero on success; non-zero otherwise. | |
41 | */ | |
42 | static int f2fs_derive_key_aes(char deriving_key[F2FS_AES_128_ECB_KEY_SIZE], | |
43 | char source_key[F2FS_AES_256_XTS_KEY_SIZE], | |
44 | char derived_key[F2FS_AES_256_XTS_KEY_SIZE]) | |
45 | { | |
46 | int res = 0; | |
47 | struct ablkcipher_request *req = NULL; | |
48 | DECLARE_F2FS_COMPLETION_RESULT(ecr); | |
49 | struct scatterlist src_sg, dst_sg; | |
50 | struct crypto_ablkcipher *tfm = crypto_alloc_ablkcipher("ecb(aes)", 0, | |
51 | 0); | |
52 | ||
53 | if (IS_ERR(tfm)) { | |
54 | res = PTR_ERR(tfm); | |
55 | tfm = NULL; | |
56 | goto out; | |
57 | } | |
58 | crypto_ablkcipher_set_flags(tfm, CRYPTO_TFM_REQ_WEAK_KEY); | |
59 | req = ablkcipher_request_alloc(tfm, GFP_NOFS); | |
60 | if (!req) { | |
61 | res = -ENOMEM; | |
62 | goto out; | |
63 | } | |
64 | ablkcipher_request_set_callback(req, | |
65 | CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, | |
66 | derive_crypt_complete, &ecr); | |
67 | res = crypto_ablkcipher_setkey(tfm, deriving_key, | |
68 | F2FS_AES_128_ECB_KEY_SIZE); | |
69 | if (res < 0) | |
70 | goto out; | |
71 | ||
72 | sg_init_one(&src_sg, source_key, F2FS_AES_256_XTS_KEY_SIZE); | |
73 | sg_init_one(&dst_sg, derived_key, F2FS_AES_256_XTS_KEY_SIZE); | |
74 | ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, | |
75 | F2FS_AES_256_XTS_KEY_SIZE, NULL); | |
76 | res = crypto_ablkcipher_encrypt(req); | |
77 | if (res == -EINPROGRESS || res == -EBUSY) { | |
78 | BUG_ON(req->base.data != &ecr); | |
79 | wait_for_completion(&ecr.completion); | |
80 | res = ecr.res; | |
81 | } | |
82 | out: | |
83 | if (req) | |
84 | ablkcipher_request_free(req); | |
85 | if (tfm) | |
86 | crypto_free_ablkcipher(tfm); | |
87 | return res; | |
88 | } | |
89 | ||
90 | void f2fs_free_encryption_info(struct inode *inode) | |
91 | { | |
92 | struct f2fs_inode_info *fi = F2FS_I(inode); | |
93 | struct f2fs_crypt_info *ci = fi->i_crypt_info; | |
94 | ||
95 | if (!ci) | |
96 | return; | |
97 | ||
98 | if (ci->ci_keyring_key) | |
99 | key_put(ci->ci_keyring_key); | |
100 | crypto_free_ablkcipher(ci->ci_ctfm); | |
101 | memzero_explicit(&ci->ci_raw, sizeof(ci->ci_raw)); | |
102 | kfree(ci); | |
103 | fi->i_crypt_info = NULL; | |
104 | } | |
105 | ||
106 | int _f2fs_get_encryption_info(struct inode *inode) | |
107 | { | |
108 | struct f2fs_inode_info *fi = F2FS_I(inode); | |
109 | struct f2fs_crypt_info *crypt_info; | |
110 | char full_key_descriptor[F2FS_KEY_DESC_PREFIX_SIZE + | |
111 | (F2FS_KEY_DESCRIPTOR_SIZE * 2) + 1]; | |
112 | struct key *keyring_key = NULL; | |
113 | struct f2fs_encryption_key *master_key; | |
114 | struct f2fs_encryption_context ctx; | |
115 | struct user_key_payload *ukp; | |
116 | int res; | |
117 | ||
118 | if (!f2fs_read_workqueue) { | |
119 | res = f2fs_init_crypto(); | |
120 | if (res) | |
121 | return res; | |
122 | } | |
123 | ||
124 | if (fi->i_crypt_info) { | |
125 | if (!fi->i_crypt_info->ci_keyring_key || | |
126 | key_validate(fi->i_crypt_info->ci_keyring_key) == 0) | |
127 | return 0; | |
128 | f2fs_free_encryption_info(inode); | |
129 | } | |
130 | ||
131 | res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION, | |
132 | F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, | |
133 | &ctx, sizeof(ctx), NULL); | |
134 | if (res < 0) | |
135 | return res; | |
136 | else if (res != sizeof(ctx)) | |
137 | return -EINVAL; | |
138 | res = 0; | |
139 | ||
140 | crypt_info = kmalloc(sizeof(struct f2fs_crypt_info), GFP_NOFS); | |
141 | if (!crypt_info) | |
142 | return -ENOMEM; | |
143 | ||
144 | crypt_info->ci_flags = ctx.flags; | |
145 | crypt_info->ci_data_mode = ctx.contents_encryption_mode; | |
146 | crypt_info->ci_filename_mode = ctx.filenames_encryption_mode; | |
147 | crypt_info->ci_ctfm = NULL; | |
148 | memcpy(crypt_info->ci_master_key, ctx.master_key_descriptor, | |
149 | sizeof(crypt_info->ci_master_key)); | |
150 | if (S_ISREG(inode->i_mode)) | |
151 | crypt_info->ci_mode = ctx.contents_encryption_mode; | |
152 | else if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)) | |
153 | crypt_info->ci_mode = ctx.filenames_encryption_mode; | |
154 | else { | |
155 | printk(KERN_ERR "f2fs crypto: Unsupported inode type.\n"); | |
156 | BUG(); | |
157 | } | |
158 | crypt_info->ci_size = f2fs_encryption_key_size(crypt_info->ci_mode); | |
159 | BUG_ON(!crypt_info->ci_size); | |
160 | ||
161 | memcpy(full_key_descriptor, F2FS_KEY_DESC_PREFIX, | |
162 | F2FS_KEY_DESC_PREFIX_SIZE); | |
163 | sprintf(full_key_descriptor + F2FS_KEY_DESC_PREFIX_SIZE, | |
164 | "%*phN", F2FS_KEY_DESCRIPTOR_SIZE, | |
165 | ctx.master_key_descriptor); | |
166 | full_key_descriptor[F2FS_KEY_DESC_PREFIX_SIZE + | |
167 | (2 * F2FS_KEY_DESCRIPTOR_SIZE)] = '\0'; | |
168 | keyring_key = request_key(&key_type_logon, full_key_descriptor, NULL); | |
169 | if (IS_ERR(keyring_key)) { | |
170 | res = PTR_ERR(keyring_key); | |
171 | keyring_key = NULL; | |
172 | goto out; | |
173 | } | |
174 | BUG_ON(keyring_key->type != &key_type_logon); | |
175 | ukp = ((struct user_key_payload *)keyring_key->payload.data); | |
176 | if (ukp->datalen != sizeof(struct f2fs_encryption_key)) { | |
177 | res = -EINVAL; | |
178 | goto out; | |
179 | } | |
180 | master_key = (struct f2fs_encryption_key *)ukp->data; | |
181 | BUILD_BUG_ON(F2FS_AES_128_ECB_KEY_SIZE != | |
182 | F2FS_KEY_DERIVATION_NONCE_SIZE); | |
183 | BUG_ON(master_key->size != F2FS_AES_256_XTS_KEY_SIZE); | |
184 | res = f2fs_derive_key_aes(ctx.nonce, master_key->raw, | |
185 | crypt_info->ci_raw); | |
186 | out: | |
187 | if (res < 0) { | |
188 | if (res == -ENOKEY) | |
189 | res = 0; | |
190 | kfree(crypt_info); | |
191 | } else { | |
192 | fi->i_crypt_info = crypt_info; | |
193 | crypt_info->ci_keyring_key = keyring_key; | |
194 | keyring_key = NULL; | |
195 | } | |
196 | if (keyring_key) | |
197 | key_put(keyring_key); | |
198 | return res; | |
199 | } | |
200 | ||
201 | int f2fs_has_encryption_key(struct inode *inode) | |
202 | { | |
203 | struct f2fs_inode_info *fi = F2FS_I(inode); | |
204 | ||
205 | return (fi->i_crypt_info != NULL); | |
206 | } |