Commit | Line | Data |
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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 | ||
26bf3dc7 | 90 | static void f2fs_free_crypt_info(struct f2fs_crypt_info *ci) |
0adda907 | 91 | { |
0adda907 JK |
92 | if (!ci) |
93 | return; | |
94 | ||
92859a5e | 95 | key_put(ci->ci_keyring_key); |
0adda907 | 96 | crypto_free_ablkcipher(ci->ci_ctfm); |
8bacf6de | 97 | kmem_cache_free(f2fs_crypt_info_cachep, ci); |
26bf3dc7 JK |
98 | } |
99 | ||
100 | void f2fs_free_encryption_info(struct inode *inode, struct f2fs_crypt_info *ci) | |
101 | { | |
102 | struct f2fs_inode_info *fi = F2FS_I(inode); | |
103 | struct f2fs_crypt_info *prev; | |
104 | ||
105 | if (ci == NULL) | |
106 | ci = ACCESS_ONCE(fi->i_crypt_info); | |
107 | if (ci == NULL) | |
108 | return; | |
109 | prev = cmpxchg(&fi->i_crypt_info, ci, NULL); | |
110 | if (prev != ci) | |
111 | return; | |
112 | ||
113 | f2fs_free_crypt_info(ci); | |
0adda907 JK |
114 | } |
115 | ||
116 | int _f2fs_get_encryption_info(struct inode *inode) | |
117 | { | |
118 | struct f2fs_inode_info *fi = F2FS_I(inode); | |
119 | struct f2fs_crypt_info *crypt_info; | |
120 | char full_key_descriptor[F2FS_KEY_DESC_PREFIX_SIZE + | |
121 | (F2FS_KEY_DESCRIPTOR_SIZE * 2) + 1]; | |
122 | struct key *keyring_key = NULL; | |
123 | struct f2fs_encryption_key *master_key; | |
124 | struct f2fs_encryption_context ctx; | |
125 | struct user_key_payload *ukp; | |
26bf3dc7 JK |
126 | struct crypto_ablkcipher *ctfm; |
127 | const char *cipher_str; | |
128 | char raw_key[F2FS_MAX_KEY_SIZE]; | |
129 | char mode; | |
0adda907 JK |
130 | int res; |
131 | ||
cfc4d971 JK |
132 | res = f2fs_crypto_initialize(); |
133 | if (res) | |
134 | return res; | |
26bf3dc7 JK |
135 | retry: |
136 | crypt_info = ACCESS_ONCE(fi->i_crypt_info); | |
137 | if (crypt_info) { | |
138 | if (!crypt_info->ci_keyring_key || | |
139 | key_validate(crypt_info->ci_keyring_key) == 0) | |
0adda907 | 140 | return 0; |
26bf3dc7 JK |
141 | f2fs_free_encryption_info(inode, crypt_info); |
142 | goto retry; | |
0adda907 JK |
143 | } |
144 | ||
145 | res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION, | |
146 | F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, | |
147 | &ctx, sizeof(ctx), NULL); | |
148 | if (res < 0) | |
149 | return res; | |
150 | else if (res != sizeof(ctx)) | |
151 | return -EINVAL; | |
152 | res = 0; | |
153 | ||
8bacf6de | 154 | crypt_info = kmem_cache_alloc(f2fs_crypt_info_cachep, GFP_NOFS); |
0adda907 JK |
155 | if (!crypt_info) |
156 | return -ENOMEM; | |
157 | ||
158 | crypt_info->ci_flags = ctx.flags; | |
159 | crypt_info->ci_data_mode = ctx.contents_encryption_mode; | |
160 | crypt_info->ci_filename_mode = ctx.filenames_encryption_mode; | |
161 | crypt_info->ci_ctfm = NULL; | |
26bf3dc7 | 162 | crypt_info->ci_keyring_key = NULL; |
0adda907 JK |
163 | memcpy(crypt_info->ci_master_key, ctx.master_key_descriptor, |
164 | sizeof(crypt_info->ci_master_key)); | |
165 | if (S_ISREG(inode->i_mode)) | |
26bf3dc7 | 166 | mode = crypt_info->ci_data_mode; |
0adda907 | 167 | else if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)) |
26bf3dc7 | 168 | mode = crypt_info->ci_filename_mode; |
640778fb | 169 | else |
0adda907 | 170 | BUG(); |
640778fb | 171 | |
26bf3dc7 JK |
172 | switch (mode) { |
173 | case F2FS_ENCRYPTION_MODE_AES_256_XTS: | |
174 | cipher_str = "xts(aes)"; | |
175 | break; | |
176 | case F2FS_ENCRYPTION_MODE_AES_256_CTS: | |
177 | cipher_str = "cts(cbc(aes))"; | |
178 | break; | |
179 | default: | |
180 | printk_once(KERN_WARNING | |
181 | "f2fs: unsupported key mode %d (ino %u)\n", | |
182 | mode, (unsigned) inode->i_ino); | |
183 | res = -ENOKEY; | |
184 | goto out; | |
185 | } | |
0adda907 JK |
186 | |
187 | memcpy(full_key_descriptor, F2FS_KEY_DESC_PREFIX, | |
188 | F2FS_KEY_DESC_PREFIX_SIZE); | |
189 | sprintf(full_key_descriptor + F2FS_KEY_DESC_PREFIX_SIZE, | |
190 | "%*phN", F2FS_KEY_DESCRIPTOR_SIZE, | |
191 | ctx.master_key_descriptor); | |
192 | full_key_descriptor[F2FS_KEY_DESC_PREFIX_SIZE + | |
193 | (2 * F2FS_KEY_DESCRIPTOR_SIZE)] = '\0'; | |
194 | keyring_key = request_key(&key_type_logon, full_key_descriptor, NULL); | |
195 | if (IS_ERR(keyring_key)) { | |
196 | res = PTR_ERR(keyring_key); | |
197 | keyring_key = NULL; | |
198 | goto out; | |
199 | } | |
26bf3dc7 | 200 | crypt_info->ci_keyring_key = keyring_key; |
0adda907 JK |
201 | BUG_ON(keyring_key->type != &key_type_logon); |
202 | ukp = ((struct user_key_payload *)keyring_key->payload.data); | |
203 | if (ukp->datalen != sizeof(struct f2fs_encryption_key)) { | |
204 | res = -EINVAL; | |
205 | goto out; | |
206 | } | |
207 | master_key = (struct f2fs_encryption_key *)ukp->data; | |
208 | BUILD_BUG_ON(F2FS_AES_128_ECB_KEY_SIZE != | |
209 | F2FS_KEY_DERIVATION_NONCE_SIZE); | |
210 | BUG_ON(master_key->size != F2FS_AES_256_XTS_KEY_SIZE); | |
211 | res = f2fs_derive_key_aes(ctx.nonce, master_key->raw, | |
26bf3dc7 JK |
212 | raw_key); |
213 | if (res) | |
214 | goto out; | |
215 | ||
216 | ctfm = crypto_alloc_ablkcipher(cipher_str, 0, 0); | |
217 | if (!ctfm || IS_ERR(ctfm)) { | |
218 | res = ctfm ? PTR_ERR(ctfm) : -ENOMEM; | |
219 | printk(KERN_DEBUG | |
220 | "%s: error %d (inode %u) allocating crypto tfm\n", | |
221 | __func__, res, (unsigned) inode->i_ino); | |
222 | goto out; | |
0adda907 | 223 | } |
26bf3dc7 JK |
224 | crypt_info->ci_ctfm = ctfm; |
225 | crypto_ablkcipher_clear_flags(ctfm, ~0); | |
226 | crypto_tfm_set_flags(crypto_ablkcipher_tfm(ctfm), | |
227 | CRYPTO_TFM_REQ_WEAK_KEY); | |
228 | res = crypto_ablkcipher_setkey(ctfm, raw_key, | |
229 | f2fs_encryption_key_size(mode)); | |
230 | if (res) | |
231 | goto out; | |
232 | ||
233 | memzero_explicit(raw_key, sizeof(raw_key)); | |
234 | if (cmpxchg(&fi->i_crypt_info, NULL, crypt_info) != NULL) { | |
235 | f2fs_free_crypt_info(crypt_info); | |
236 | goto retry; | |
237 | } | |
238 | return 0; | |
239 | ||
240 | out: | |
241 | if (res == -ENOKEY && !S_ISREG(inode->i_mode)) | |
242 | res = 0; | |
243 | ||
244 | f2fs_free_crypt_info(crypt_info); | |
245 | memzero_explicit(raw_key, sizeof(raw_key)); | |
0adda907 JK |
246 | return res; |
247 | } | |
248 | ||
249 | int f2fs_has_encryption_key(struct inode *inode) | |
250 | { | |
251 | struct f2fs_inode_info *fi = F2FS_I(inode); | |
252 | ||
253 | return (fi->i_crypt_info != NULL); | |
254 | } |