2 * linux/fs/f2fs/crypto_key.c
4 * Copied from linux/fs/f2fs/crypto_key.c
6 * Copyright (C) 2015, Google, Inc.
8 * This contains encryption key functions for f2fs
10 * Written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar, 2015.
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/skcipher.h>
18 #include <linux/f2fs_fs.h>
23 static void derive_crypt_complete(struct crypto_async_request
*req
, int rc
)
25 struct f2fs_completion_result
*ecr
= req
->data
;
27 if (rc
== -EINPROGRESS
)
31 complete(&ecr
->completion
);
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.
40 * Return: Zero on success; non-zero otherwise.
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
])
47 struct skcipher_request
*req
= NULL
;
48 DECLARE_F2FS_COMPLETION_RESULT(ecr
);
49 struct scatterlist src_sg
, dst_sg
;
50 struct crypto_skcipher
*tfm
= crypto_alloc_skcipher("ecb(aes)", 0, 0);
57 crypto_skcipher_set_flags(tfm
, CRYPTO_TFM_REQ_WEAK_KEY
);
58 req
= skcipher_request_alloc(tfm
, GFP_NOFS
);
63 skcipher_request_set_callback(req
,
64 CRYPTO_TFM_REQ_MAY_BACKLOG
| CRYPTO_TFM_REQ_MAY_SLEEP
,
65 derive_crypt_complete
, &ecr
);
66 res
= crypto_skcipher_setkey(tfm
, deriving_key
,
67 F2FS_AES_128_ECB_KEY_SIZE
);
71 sg_init_one(&src_sg
, source_key
, F2FS_AES_256_XTS_KEY_SIZE
);
72 sg_init_one(&dst_sg
, derived_key
, F2FS_AES_256_XTS_KEY_SIZE
);
73 skcipher_request_set_crypt(req
, &src_sg
, &dst_sg
,
74 F2FS_AES_256_XTS_KEY_SIZE
, NULL
);
75 res
= crypto_skcipher_encrypt(req
);
76 if (res
== -EINPROGRESS
|| res
== -EBUSY
) {
77 BUG_ON(req
->base
.data
!= &ecr
);
78 wait_for_completion(&ecr
.completion
);
82 skcipher_request_free(req
);
83 crypto_free_skcipher(tfm
);
87 static void f2fs_free_crypt_info(struct f2fs_crypt_info
*ci
)
92 key_put(ci
->ci_keyring_key
);
93 crypto_free_skcipher(ci
->ci_ctfm
);
94 kmem_cache_free(f2fs_crypt_info_cachep
, ci
);
97 void f2fs_free_encryption_info(struct inode
*inode
, struct f2fs_crypt_info
*ci
)
99 struct f2fs_inode_info
*fi
= F2FS_I(inode
);
100 struct f2fs_crypt_info
*prev
;
103 ci
= ACCESS_ONCE(fi
->i_crypt_info
);
106 prev
= cmpxchg(&fi
->i_crypt_info
, ci
, NULL
);
110 f2fs_free_crypt_info(ci
);
113 int _f2fs_get_encryption_info(struct inode
*inode
)
115 struct f2fs_inode_info
*fi
= F2FS_I(inode
);
116 struct f2fs_crypt_info
*crypt_info
;
117 char full_key_descriptor
[F2FS_KEY_DESC_PREFIX_SIZE
+
118 (F2FS_KEY_DESCRIPTOR_SIZE
* 2) + 1];
119 struct key
*keyring_key
= NULL
;
120 struct f2fs_encryption_key
*master_key
;
121 struct f2fs_encryption_context ctx
;
122 const struct user_key_payload
*ukp
;
123 struct crypto_skcipher
*ctfm
;
124 const char *cipher_str
;
125 char raw_key
[F2FS_MAX_KEY_SIZE
];
129 res
= f2fs_crypto_initialize();
133 crypt_info
= ACCESS_ONCE(fi
->i_crypt_info
);
135 if (!crypt_info
->ci_keyring_key
||
136 key_validate(crypt_info
->ci_keyring_key
) == 0)
138 f2fs_free_encryption_info(inode
, crypt_info
);
142 res
= f2fs_getxattr(inode
, F2FS_XATTR_INDEX_ENCRYPTION
,
143 F2FS_XATTR_NAME_ENCRYPTION_CONTEXT
,
144 &ctx
, sizeof(ctx
), NULL
);
147 else if (res
!= sizeof(ctx
))
151 crypt_info
= kmem_cache_alloc(f2fs_crypt_info_cachep
, GFP_NOFS
);
155 crypt_info
->ci_flags
= ctx
.flags
;
156 crypt_info
->ci_data_mode
= ctx
.contents_encryption_mode
;
157 crypt_info
->ci_filename_mode
= ctx
.filenames_encryption_mode
;
158 crypt_info
->ci_ctfm
= NULL
;
159 crypt_info
->ci_keyring_key
= NULL
;
160 memcpy(crypt_info
->ci_master_key
, ctx
.master_key_descriptor
,
161 sizeof(crypt_info
->ci_master_key
));
162 if (S_ISREG(inode
->i_mode
))
163 mode
= crypt_info
->ci_data_mode
;
164 else if (S_ISDIR(inode
->i_mode
) || S_ISLNK(inode
->i_mode
))
165 mode
= crypt_info
->ci_filename_mode
;
170 case F2FS_ENCRYPTION_MODE_AES_256_XTS
:
171 cipher_str
= "xts(aes)";
173 case F2FS_ENCRYPTION_MODE_AES_256_CTS
:
174 cipher_str
= "cts(cbc(aes))";
177 printk_once(KERN_WARNING
178 "f2fs: unsupported key mode %d (ino %u)\n",
179 mode
, (unsigned) inode
->i_ino
);
184 memcpy(full_key_descriptor
, F2FS_KEY_DESC_PREFIX
,
185 F2FS_KEY_DESC_PREFIX_SIZE
);
186 sprintf(full_key_descriptor
+ F2FS_KEY_DESC_PREFIX_SIZE
,
187 "%*phN", F2FS_KEY_DESCRIPTOR_SIZE
,
188 ctx
.master_key_descriptor
);
189 full_key_descriptor
[F2FS_KEY_DESC_PREFIX_SIZE
+
190 (2 * F2FS_KEY_DESCRIPTOR_SIZE
)] = '\0';
191 keyring_key
= request_key(&key_type_logon
, full_key_descriptor
, NULL
);
192 if (IS_ERR(keyring_key
)) {
193 res
= PTR_ERR(keyring_key
);
197 crypt_info
->ci_keyring_key
= keyring_key
;
198 BUG_ON(keyring_key
->type
!= &key_type_logon
);
199 ukp
= user_key_payload(keyring_key
);
200 if (ukp
->datalen
!= sizeof(struct f2fs_encryption_key
)) {
204 master_key
= (struct f2fs_encryption_key
*)ukp
->data
;
205 BUILD_BUG_ON(F2FS_AES_128_ECB_KEY_SIZE
!=
206 F2FS_KEY_DERIVATION_NONCE_SIZE
);
207 BUG_ON(master_key
->size
!= F2FS_AES_256_XTS_KEY_SIZE
);
208 res
= f2fs_derive_key_aes(ctx
.nonce
, master_key
->raw
,
213 ctfm
= crypto_alloc_skcipher(cipher_str
, 0, 0);
214 if (!ctfm
|| IS_ERR(ctfm
)) {
215 res
= ctfm
? PTR_ERR(ctfm
) : -ENOMEM
;
217 "%s: error %d (inode %u) allocating crypto tfm\n",
218 __func__
, res
, (unsigned) inode
->i_ino
);
221 crypt_info
->ci_ctfm
= ctfm
;
222 crypto_skcipher_clear_flags(ctfm
, ~0);
223 crypto_skcipher_set_flags(ctfm
, CRYPTO_TFM_REQ_WEAK_KEY
);
224 res
= crypto_skcipher_setkey(ctfm
, raw_key
,
225 f2fs_encryption_key_size(mode
));
229 memzero_explicit(raw_key
, sizeof(raw_key
));
230 if (cmpxchg(&fi
->i_crypt_info
, NULL
, crypt_info
) != NULL
) {
231 f2fs_free_crypt_info(crypt_info
);
237 if (res
== -ENOKEY
&& !S_ISREG(inode
->i_mode
))
240 f2fs_free_crypt_info(crypt_info
);
241 memzero_explicit(raw_key
, sizeof(raw_key
));
245 int f2fs_has_encryption_key(struct inode
*inode
)
247 struct f2fs_inode_info
*fi
= F2FS_I(inode
);
249 return (fi
->i_crypt_info
!= NULL
);