Commit | Line | Data |
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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
3325bea5 TT |
2 | /* |
3 | * fscrypt_private.h | |
4 | * | |
5 | * Copyright (C) 2015, Google, Inc. | |
6 | * | |
3ec4f2a6 EB |
7 | * Originally written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar. |
8 | * Heavily modified since then. | |
3325bea5 TT |
9 | */ |
10 | ||
11 | #ifndef _FSCRYPT_PRIVATE_H | |
12 | #define _FSCRYPT_PRIVATE_H | |
13 | ||
734f0d24 | 14 | #include <linux/fscrypt.h> |
aa408f83 | 15 | #include <linux/siphash.h> |
b7e7cf7a | 16 | #include <crypto/hash.h> |
5fee3609 | 17 | #include <linux/blk-crypto.h> |
3325bea5 | 18 | |
22d94f49 EB |
19 | #define CONST_STRLEN(str) (sizeof(str) - 1) |
20 | ||
1d6217a4 | 21 | #define FSCRYPT_FILE_NONCE_SIZE 16 |
cc4e0df0 | 22 | |
b7e072f9 EB |
23 | /* |
24 | * Minimum size of an fscrypt master key. Note: a longer key will be required | |
25 | * if ciphers with a 256-bit security strength are used. This is just the | |
26 | * absolute minimum, which applies when only 128-bit encryption is used. | |
27 | */ | |
1d6217a4 | 28 | #define FSCRYPT_MIN_KEY_SIZE 16 |
22d94f49 | 29 | |
5dae460c EB |
30 | #define FSCRYPT_CONTEXT_V1 1 |
31 | #define FSCRYPT_CONTEXT_V2 2 | |
32 | ||
3ceb6543 | 33 | /* Keep this in sync with include/uapi/linux/fscrypt.h */ |
6b2a51ff | 34 | #define FSCRYPT_MODE_MAX FSCRYPT_MODE_AES_256_HCTR2 |
3ceb6543 | 35 | |
5dae460c EB |
36 | struct fscrypt_context_v1 { |
37 | u8 version; /* FSCRYPT_CONTEXT_V1 */ | |
cc4e0df0 TT |
38 | u8 contents_encryption_mode; |
39 | u8 filenames_encryption_mode; | |
40 | u8 flags; | |
3b6df59b | 41 | u8 master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE]; |
1d6217a4 | 42 | u8 nonce[FSCRYPT_FILE_NONCE_SIZE]; |
5dae460c | 43 | }; |
cc4e0df0 | 44 | |
5dae460c EB |
45 | struct fscrypt_context_v2 { |
46 | u8 version; /* FSCRYPT_CONTEXT_V2 */ | |
47 | u8 contents_encryption_mode; | |
48 | u8 filenames_encryption_mode; | |
49 | u8 flags; | |
50 | u8 __reserved[4]; | |
51 | u8 master_key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]; | |
1d6217a4 | 52 | u8 nonce[FSCRYPT_FILE_NONCE_SIZE]; |
5dae460c EB |
53 | }; |
54 | ||
d2fe9754 | 55 | /* |
5dae460c EB |
56 | * fscrypt_context - the encryption context of an inode |
57 | * | |
58 | * This is the on-disk equivalent of an fscrypt_policy, stored alongside each | |
59 | * encrypted file usually in a hidden extended attribute. It contains the | |
60 | * fields from the fscrypt_policy, in order to identify the encryption algorithm | |
61 | * and key with which the file is encrypted. It also contains a nonce that was | |
62 | * randomly generated by fscrypt itself; this is used as KDF input or as a tweak | |
63 | * to cause different files to be encrypted differently. | |
64 | */ | |
65 | union fscrypt_context { | |
66 | u8 version; | |
67 | struct fscrypt_context_v1 v1; | |
68 | struct fscrypt_context_v2 v2; | |
69 | }; | |
70 | ||
71 | /* | |
72 | * Return the size expected for the given fscrypt_context based on its version | |
73 | * number, or 0 if the context version is unrecognized. | |
74 | */ | |
75 | static inline int fscrypt_context_size(const union fscrypt_context *ctx) | |
76 | { | |
77 | switch (ctx->version) { | |
78 | case FSCRYPT_CONTEXT_V1: | |
79 | BUILD_BUG_ON(sizeof(ctx->v1) != 28); | |
80 | return sizeof(ctx->v1); | |
81 | case FSCRYPT_CONTEXT_V2: | |
82 | BUILD_BUG_ON(sizeof(ctx->v2) != 40); | |
83 | return sizeof(ctx->v2); | |
84 | } | |
85 | return 0; | |
86 | } | |
87 | ||
e98ad464 EB |
88 | /* Check whether an fscrypt_context has a recognized version number and size */ |
89 | static inline bool fscrypt_context_is_valid(const union fscrypt_context *ctx, | |
90 | int ctx_size) | |
91 | { | |
92 | return ctx_size >= 1 && ctx_size == fscrypt_context_size(ctx); | |
93 | } | |
94 | ||
95 | /* Retrieve the context's nonce, assuming the context was already validated */ | |
96 | static inline const u8 *fscrypt_context_nonce(const union fscrypt_context *ctx) | |
97 | { | |
98 | switch (ctx->version) { | |
99 | case FSCRYPT_CONTEXT_V1: | |
100 | return ctx->v1.nonce; | |
101 | case FSCRYPT_CONTEXT_V2: | |
102 | return ctx->v2.nonce; | |
103 | } | |
41b2ad80 | 104 | WARN_ON_ONCE(1); |
e98ad464 EB |
105 | return NULL; |
106 | } | |
107 | ||
5dae460c EB |
108 | union fscrypt_policy { |
109 | u8 version; | |
110 | struct fscrypt_policy_v1 v1; | |
111 | struct fscrypt_policy_v2 v2; | |
112 | }; | |
113 | ||
114 | /* | |
115 | * Return the size expected for the given fscrypt_policy based on its version | |
116 | * number, or 0 if the policy version is unrecognized. | |
117 | */ | |
118 | static inline int fscrypt_policy_size(const union fscrypt_policy *policy) | |
119 | { | |
120 | switch (policy->version) { | |
121 | case FSCRYPT_POLICY_V1: | |
122 | return sizeof(policy->v1); | |
123 | case FSCRYPT_POLICY_V2: | |
124 | return sizeof(policy->v2); | |
125 | } | |
126 | return 0; | |
127 | } | |
128 | ||
129 | /* Return the contents encryption mode of a valid encryption policy */ | |
130 | static inline u8 | |
131 | fscrypt_policy_contents_mode(const union fscrypt_policy *policy) | |
132 | { | |
133 | switch (policy->version) { | |
134 | case FSCRYPT_POLICY_V1: | |
135 | return policy->v1.contents_encryption_mode; | |
136 | case FSCRYPT_POLICY_V2: | |
137 | return policy->v2.contents_encryption_mode; | |
138 | } | |
139 | BUG(); | |
140 | } | |
141 | ||
142 | /* Return the filenames encryption mode of a valid encryption policy */ | |
143 | static inline u8 | |
144 | fscrypt_policy_fnames_mode(const union fscrypt_policy *policy) | |
145 | { | |
146 | switch (policy->version) { | |
147 | case FSCRYPT_POLICY_V1: | |
148 | return policy->v1.filenames_encryption_mode; | |
149 | case FSCRYPT_POLICY_V2: | |
150 | return policy->v2.filenames_encryption_mode; | |
151 | } | |
152 | BUG(); | |
153 | } | |
154 | ||
155 | /* Return the flags (FSCRYPT_POLICY_FLAG*) of a valid encryption policy */ | |
156 | static inline u8 | |
157 | fscrypt_policy_flags(const union fscrypt_policy *policy) | |
158 | { | |
159 | switch (policy->version) { | |
160 | case FSCRYPT_POLICY_V1: | |
161 | return policy->v1.flags; | |
162 | case FSCRYPT_POLICY_V2: | |
163 | return policy->v2.flags; | |
164 | } | |
165 | BUG(); | |
166 | } | |
167 | ||
d2fe9754 | 168 | /* |
0eaab5b1 EB |
169 | * For encrypted symlinks, the ciphertext length is stored at the beginning |
170 | * of the string in little-endian format. | |
171 | */ | |
172 | struct fscrypt_symlink_data { | |
173 | __le16 len; | |
174 | char encrypted_path[1]; | |
175 | } __packed; | |
176 | ||
5fee3609 ST |
177 | /** |
178 | * struct fscrypt_prepared_key - a key prepared for actual encryption/decryption | |
179 | * @tfm: crypto API transform object | |
180 | * @blk_key: key for blk-crypto | |
181 | * | |
182 | * Normally only one of the fields will be non-NULL. | |
183 | */ | |
184 | struct fscrypt_prepared_key { | |
185 | struct crypto_skcipher *tfm; | |
186 | #ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT | |
22e9947a | 187 | struct blk_crypto_key *blk_key; |
5fee3609 ST |
188 | #endif |
189 | }; | |
190 | ||
cc4e0df0 | 191 | /* |
8094c3ce EB |
192 | * fscrypt_info - the "encryption key" for an inode |
193 | * | |
194 | * When an encrypted file's key is made available, an instance of this struct is | |
195 | * allocated and stored in ->i_crypt_info. Once created, it remains until the | |
196 | * inode is evicted. | |
cc4e0df0 TT |
197 | */ |
198 | struct fscrypt_info { | |
8094c3ce | 199 | |
5fee3609 ST |
200 | /* The key in a form prepared for actual encryption/decryption */ |
201 | struct fscrypt_prepared_key ci_enc_key; | |
8094c3ce | 202 | |
5fee3609 | 203 | /* True if ci_enc_key should be freed when this fscrypt_info is freed */ |
b103fb76 EB |
204 | bool ci_owns_key; |
205 | ||
5fee3609 ST |
206 | #ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT |
207 | /* | |
208 | * True if this inode will use inline encryption (blk-crypto) instead of | |
209 | * the traditional filesystem-layer encryption. | |
210 | */ | |
211 | bool ci_inlinecrypt; | |
212 | #endif | |
213 | ||
8094c3ce | 214 | /* |
5dae460c EB |
215 | * Encryption mode used for this inode. It corresponds to either the |
216 | * contents or filenames encryption mode, depending on the inode type. | |
8094c3ce EB |
217 | */ |
218 | struct fscrypt_mode *ci_mode; | |
219 | ||
59dc6a8e EB |
220 | /* Back-pointer to the inode */ |
221 | struct inode *ci_inode; | |
222 | ||
b1c0ec35 EB |
223 | /* |
224 | * The master key with which this inode was unlocked (decrypted). This | |
225 | * will be NULL if the master key was found in a process-subscribed | |
226 | * keyring rather than in the filesystem-level keyring. | |
227 | */ | |
d7e7b9af | 228 | struct fscrypt_master_key *ci_master_key; |
b1c0ec35 EB |
229 | |
230 | /* | |
231 | * Link in list of inodes that were unlocked with the master key. | |
232 | * Only used when ->ci_master_key is set. | |
233 | */ | |
234 | struct list_head ci_master_key_link; | |
235 | ||
8094c3ce | 236 | /* |
a828daab | 237 | * If non-NULL, then encryption is done using the master key directly |
5fee3609 | 238 | * and ci_enc_key will equal ci_direct_key->dk_key. |
8094c3ce | 239 | */ |
a828daab | 240 | struct fscrypt_direct_key *ci_direct_key; |
8094c3ce | 241 | |
aa408f83 DR |
242 | /* |
243 | * This inode's hash key for filenames. This is a 128-bit SipHash-2-4 | |
244 | * key. This is only set for directories that use a keyed dirhash over | |
245 | * the plaintext filenames -- currently just casefolded directories. | |
246 | */ | |
247 | siphash_key_t ci_dirhash_key; | |
248 | bool ci_dirhash_key_initialized; | |
249 | ||
5dae460c EB |
250 | /* The encryption policy used by this inode */ |
251 | union fscrypt_policy ci_policy; | |
252 | ||
253 | /* This inode's nonce, copied from the fscrypt_context */ | |
1d6217a4 | 254 | u8 ci_nonce[FSCRYPT_FILE_NONCE_SIZE]; |
e3b1078b EB |
255 | |
256 | /* Hashed inode number. Only set for IV_INO_LBLK_32 */ | |
257 | u32 ci_hashed_ino; | |
cc4e0df0 TT |
258 | }; |
259 | ||
58ae7468 RW |
260 | typedef enum { |
261 | FS_DECRYPT = 0, | |
262 | FS_ENCRYPT, | |
263 | } fscrypt_direction_t; | |
264 | ||
b98701df | 265 | /* crypto.c */ |
e4de782a | 266 | extern struct kmem_cache *fscrypt_info_cachep; |
83e57e47 | 267 | int fscrypt_initialize(struct super_block *sb); |
60700902 EB |
268 | int fscrypt_crypt_block(const struct inode *inode, fscrypt_direction_t rw, |
269 | u64 lblk_num, struct page *src_page, | |
270 | struct page *dest_page, unsigned int len, | |
271 | unsigned int offs, gfp_t gfp_flags); | |
272 | struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags); | |
273 | ||
274 | void __printf(3, 4) __cold | |
886da8b3 | 275 | fscrypt_msg(const struct inode *inode, const char *level, const char *fmt, ...); |
544d08fd | 276 | |
886da8b3 EB |
277 | #define fscrypt_warn(inode, fmt, ...) \ |
278 | fscrypt_msg((inode), KERN_WARNING, fmt, ##__VA_ARGS__) | |
279 | #define fscrypt_err(inode, fmt, ...) \ | |
280 | fscrypt_msg((inode), KERN_ERR, fmt, ##__VA_ARGS__) | |
544d08fd | 281 | |
8094c3ce EB |
282 | #define FSCRYPT_MAX_IV_SIZE 32 |
283 | ||
284 | union fscrypt_iv { | |
285 | struct { | |
286 | /* logical block number within the file */ | |
287 | __le64 lblk_num; | |
288 | ||
289 | /* per-file nonce; only set in DIRECT_KEY mode */ | |
1d6217a4 | 290 | u8 nonce[FSCRYPT_FILE_NONCE_SIZE]; |
8094c3ce EB |
291 | }; |
292 | u8 raw[FSCRYPT_MAX_IV_SIZE]; | |
5fee3609 | 293 | __le64 dun[FSCRYPT_MAX_IV_SIZE / sizeof(__le64)]; |
8094c3ce EB |
294 | }; |
295 | ||
296 | void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num, | |
297 | const struct fscrypt_info *ci); | |
298 | ||
76e81d6d | 299 | /* fname.c */ |
d3e94fdc JL |
300 | bool __fscrypt_fname_encrypted_size(const union fscrypt_policy *policy, |
301 | u32 orig_len, u32 max_len, | |
302 | u32 *encrypted_len_ret); | |
76e81d6d | 303 | |
c1144c9b | 304 | /* hkdf.c */ |
c1144c9b EB |
305 | struct fscrypt_hkdf { |
306 | struct crypto_shash *hmac_tfm; | |
307 | }; | |
308 | ||
60700902 EB |
309 | int fscrypt_init_hkdf(struct fscrypt_hkdf *hkdf, const u8 *master_key, |
310 | unsigned int master_key_size); | |
c1144c9b | 311 | |
5dae460c EB |
312 | /* |
313 | * The list of contexts in which fscrypt uses HKDF. These values are used as | |
314 | * the first byte of the HKDF application-specific info string to guarantee that | |
315 | * info strings are never repeated between contexts. This ensures that all HKDF | |
316 | * outputs are unique and cryptographically isolated, i.e. knowledge of one | |
317 | * output doesn't reveal another. | |
318 | */ | |
e455de31 EB |
319 | #define HKDF_CONTEXT_KEY_IDENTIFIER 1 /* info=<empty> */ |
320 | #define HKDF_CONTEXT_PER_FILE_ENC_KEY 2 /* info=file_nonce */ | |
321 | #define HKDF_CONTEXT_DIRECT_KEY 3 /* info=mode_num */ | |
322 | #define HKDF_CONTEXT_IV_INO_LBLK_64_KEY 4 /* info=mode_num||fs_uuid */ | |
323 | #define HKDF_CONTEXT_DIRHASH_KEY 5 /* info=file_nonce */ | |
324 | #define HKDF_CONTEXT_IV_INO_LBLK_32_KEY 6 /* info=mode_num||fs_uuid */ | |
325 | #define HKDF_CONTEXT_INODE_HASH_KEY 7 /* info=<empty> */ | |
5dae460c | 326 | |
60700902 EB |
327 | int fscrypt_hkdf_expand(const struct fscrypt_hkdf *hkdf, u8 context, |
328 | const u8 *info, unsigned int infolen, | |
329 | u8 *okm, unsigned int okmlen); | |
c1144c9b | 330 | |
60700902 | 331 | void fscrypt_destroy_hkdf(struct fscrypt_hkdf *hkdf); |
c1144c9b | 332 | |
5fee3609 ST |
333 | /* inline_crypt.c */ |
334 | #ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT | |
335 | int fscrypt_select_encryption_impl(struct fscrypt_info *ci); | |
336 | ||
337 | static inline bool | |
338 | fscrypt_using_inline_encryption(const struct fscrypt_info *ci) | |
339 | { | |
340 | return ci->ci_inlinecrypt; | |
341 | } | |
342 | ||
343 | int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key, | |
344 | const u8 *raw_key, | |
345 | const struct fscrypt_info *ci); | |
346 | ||
22e9947a EB |
347 | void fscrypt_destroy_inline_crypt_key(struct super_block *sb, |
348 | struct fscrypt_prepared_key *prep_key); | |
5fee3609 ST |
349 | |
350 | /* | |
351 | * Check whether the crypto transform or blk-crypto key has been allocated in | |
352 | * @prep_key, depending on which encryption implementation the file will use. | |
353 | */ | |
354 | static inline bool | |
355 | fscrypt_is_key_prepared(struct fscrypt_prepared_key *prep_key, | |
356 | const struct fscrypt_info *ci) | |
357 | { | |
358 | /* | |
97c6327f EB |
359 | * The two smp_load_acquire()'s here pair with the smp_store_release()'s |
360 | * in fscrypt_prepare_inline_crypt_key() and fscrypt_prepare_key(). | |
361 | * I.e., in some cases (namely, if this prep_key is a per-mode | |
362 | * encryption key) another task can publish blk_key or tfm concurrently, | |
363 | * executing a RELEASE barrier. We need to use smp_load_acquire() here | |
364 | * to safely ACQUIRE the memory the other task published. | |
5fee3609 ST |
365 | */ |
366 | if (fscrypt_using_inline_encryption(ci)) | |
97c6327f EB |
367 | return smp_load_acquire(&prep_key->blk_key) != NULL; |
368 | return smp_load_acquire(&prep_key->tfm) != NULL; | |
5fee3609 ST |
369 | } |
370 | ||
371 | #else /* CONFIG_FS_ENCRYPTION_INLINE_CRYPT */ | |
372 | ||
373 | static inline int fscrypt_select_encryption_impl(struct fscrypt_info *ci) | |
374 | { | |
375 | return 0; | |
376 | } | |
377 | ||
378 | static inline bool | |
379 | fscrypt_using_inline_encryption(const struct fscrypt_info *ci) | |
380 | { | |
381 | return false; | |
382 | } | |
383 | ||
384 | static inline int | |
385 | fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key, | |
386 | const u8 *raw_key, | |
387 | const struct fscrypt_info *ci) | |
388 | { | |
41b2ad80 | 389 | WARN_ON_ONCE(1); |
5fee3609 ST |
390 | return -EOPNOTSUPP; |
391 | } | |
392 | ||
393 | static inline void | |
22e9947a EB |
394 | fscrypt_destroy_inline_crypt_key(struct super_block *sb, |
395 | struct fscrypt_prepared_key *prep_key) | |
5fee3609 ST |
396 | { |
397 | } | |
398 | ||
399 | static inline bool | |
400 | fscrypt_is_key_prepared(struct fscrypt_prepared_key *prep_key, | |
401 | const struct fscrypt_info *ci) | |
402 | { | |
97c6327f | 403 | return smp_load_acquire(&prep_key->tfm) != NULL; |
5fee3609 ST |
404 | } |
405 | #endif /* !CONFIG_FS_ENCRYPTION_INLINE_CRYPT */ | |
406 | ||
22d94f49 EB |
407 | /* keyring.c */ |
408 | ||
409 | /* | |
410 | * fscrypt_master_key_secret - secret key material of an in-use master key | |
411 | */ | |
412 | struct fscrypt_master_key_secret { | |
413 | ||
5dae460c EB |
414 | /* |
415 | * For v2 policy keys: HKDF context keyed by this master key. | |
416 | * For v1 policy keys: not set (hkdf.hmac_tfm == NULL). | |
417 | */ | |
418 | struct fscrypt_hkdf hkdf; | |
419 | ||
b7e072f9 EB |
420 | /* |
421 | * Size of the raw key in bytes. This remains set even if ->raw was | |
422 | * zeroized due to no longer being needed. I.e. we still remember the | |
423 | * size of the key even if we don't need to remember the key itself. | |
424 | */ | |
22d94f49 EB |
425 | u32 size; |
426 | ||
5dae460c | 427 | /* For v1 policy keys: the raw key. Wiped for v2 policy keys. */ |
22d94f49 EB |
428 | u8 raw[FSCRYPT_MAX_KEY_SIZE]; |
429 | ||
430 | } __randomize_layout; | |
431 | ||
432 | /* | |
433 | * fscrypt_master_key - an in-use master key | |
434 | * | |
435 | * This represents a master encryption key which has been added to the | |
436 | * filesystem and can be used to "unlock" the encrypted files which were | |
437 | * encrypted with it. | |
438 | */ | |
439 | struct fscrypt_master_key { | |
440 | ||
d7e7b9af | 441 | /* |
02aef422 | 442 | * Link in ->s_master_keys->key_hashtable. |
d7e7b9af EB |
443 | * Only valid if ->mk_active_refs > 0. |
444 | */ | |
445 | struct hlist_node mk_node; | |
446 | ||
447 | /* Semaphore that protects ->mk_secret and ->mk_users */ | |
448 | struct rw_semaphore mk_sem; | |
449 | ||
450 | /* | |
451 | * Active and structural reference counts. An active ref guarantees | |
452 | * that the struct continues to exist, continues to be in the keyring | |
02aef422 | 453 | * ->s_master_keys, and that any embedded subkeys (e.g. |
d7e7b9af EB |
454 | * ->mk_direct_keys) that have been prepared continue to exist. |
455 | * A structural ref only guarantees that the struct continues to exist. | |
456 | * | |
457 | * There is one active ref associated with ->mk_secret being present, | |
458 | * and one active ref for each inode in ->mk_decrypted_inodes. | |
459 | * | |
460 | * There is one structural ref associated with the active refcount being | |
461 | * nonzero. Finding a key in the keyring also takes a structural ref, | |
462 | * which is then held temporarily while the key is operated on. | |
463 | */ | |
464 | refcount_t mk_active_refs; | |
465 | refcount_t mk_struct_refs; | |
466 | ||
467 | struct rcu_head mk_rcu_head; | |
468 | ||
b1c0ec35 EB |
469 | /* |
470 | * The secret key material. After FS_IOC_REMOVE_ENCRYPTION_KEY is | |
471 | * executed, this is wiped and no new inodes can be unlocked with this | |
472 | * key; however, there may still be inodes in ->mk_decrypted_inodes | |
473 | * which could not be evicted. As long as some inodes still remain, | |
474 | * FS_IOC_REMOVE_ENCRYPTION_KEY can be retried, or | |
475 | * FS_IOC_ADD_ENCRYPTION_KEY can add the secret again. | |
476 | * | |
d7e7b9af EB |
477 | * While ->mk_secret is present, one ref in ->mk_active_refs is held. |
478 | * | |
479 | * Locking: protected by ->mk_sem. The manipulation of ->mk_active_refs | |
480 | * associated with this field is protected by ->mk_sem as well. | |
b1c0ec35 | 481 | */ |
22d94f49 EB |
482 | struct fscrypt_master_key_secret mk_secret; |
483 | ||
5dae460c EB |
484 | /* |
485 | * For v1 policy keys: an arbitrary key descriptor which was assigned by | |
486 | * userspace (->descriptor). | |
487 | * | |
488 | * For v2 policy keys: a cryptographic hash of this key (->identifier). | |
489 | */ | |
22d94f49 EB |
490 | struct fscrypt_key_specifier mk_spec; |
491 | ||
23c688b5 EB |
492 | /* |
493 | * Keyring which contains a key of type 'key_type_fscrypt_user' for each | |
494 | * user who has added this key. Normally each key will be added by just | |
495 | * one user, but it's possible that multiple users share a key, and in | |
496 | * that case we need to keep track of those users so that one user can't | |
497 | * remove the key before the others want it removed too. | |
498 | * | |
499 | * This is NULL for v1 policy keys; those can only be added by root. | |
500 | * | |
d7e7b9af EB |
501 | * Locking: protected by ->mk_sem. (We don't just rely on the keyrings |
502 | * subsystem semaphore ->mk_users->sem, as we need support for atomic | |
503 | * search+insert along with proper synchronization with ->mk_secret.) | |
23c688b5 EB |
504 | */ |
505 | struct key *mk_users; | |
506 | ||
b1c0ec35 EB |
507 | /* |
508 | * List of inodes that were unlocked using this key. This allows the | |
509 | * inodes to be evicted efficiently if the key is removed. | |
510 | */ | |
511 | struct list_head mk_decrypted_inodes; | |
512 | spinlock_t mk_decrypted_inodes_lock; | |
513 | ||
b103fb76 | 514 | /* |
e3b1078b EB |
515 | * Per-mode encryption keys for the various types of encryption policies |
516 | * that use them. Allocated and derived on-demand. | |
b103fb76 | 517 | */ |
3ceb6543 EB |
518 | struct fscrypt_prepared_key mk_direct_keys[FSCRYPT_MODE_MAX + 1]; |
519 | struct fscrypt_prepared_key mk_iv_ino_lblk_64_keys[FSCRYPT_MODE_MAX + 1]; | |
520 | struct fscrypt_prepared_key mk_iv_ino_lblk_32_keys[FSCRYPT_MODE_MAX + 1]; | |
e3b1078b EB |
521 | |
522 | /* Hash key for inode numbers. Initialized only when needed. */ | |
523 | siphash_key_t mk_ino_hash_key; | |
524 | bool mk_ino_hash_key_initialized; | |
5dae460c | 525 | |
22d94f49 EB |
526 | } __randomize_layout; |
527 | ||
b1c0ec35 EB |
528 | static inline bool |
529 | is_master_key_secret_present(const struct fscrypt_master_key_secret *secret) | |
530 | { | |
531 | /* | |
d7e7b9af EB |
532 | * The READ_ONCE() is only necessary for fscrypt_drop_inode(). |
533 | * fscrypt_drop_inode() runs in atomic context, so it can't take the key | |
534 | * semaphore and thus 'secret' can change concurrently which would be a | |
535 | * data race. But fscrypt_drop_inode() only need to know whether the | |
4a4b8721 | 536 | * secret *was* present at the time of check, so READ_ONCE() suffices. |
b1c0ec35 EB |
537 | */ |
538 | return READ_ONCE(secret->size) != 0; | |
539 | } | |
540 | ||
22d94f49 EB |
541 | static inline const char *master_key_spec_type( |
542 | const struct fscrypt_key_specifier *spec) | |
543 | { | |
544 | switch (spec->type) { | |
545 | case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR: | |
546 | return "descriptor"; | |
5dae460c EB |
547 | case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER: |
548 | return "identifier"; | |
22d94f49 EB |
549 | } |
550 | return "[unknown]"; | |
551 | } | |
552 | ||
553 | static inline int master_key_spec_len(const struct fscrypt_key_specifier *spec) | |
554 | { | |
555 | switch (spec->type) { | |
556 | case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR: | |
557 | return FSCRYPT_KEY_DESCRIPTOR_SIZE; | |
5dae460c EB |
558 | case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER: |
559 | return FSCRYPT_KEY_IDENTIFIER_SIZE; | |
22d94f49 EB |
560 | } |
561 | return 0; | |
562 | } | |
563 | ||
d7e7b9af EB |
564 | void fscrypt_put_master_key(struct fscrypt_master_key *mk); |
565 | ||
02aef422 EB |
566 | void fscrypt_put_master_key_activeref(struct super_block *sb, |
567 | struct fscrypt_master_key *mk); | |
d7e7b9af EB |
568 | |
569 | struct fscrypt_master_key * | |
22d94f49 EB |
570 | fscrypt_find_master_key(struct super_block *sb, |
571 | const struct fscrypt_key_specifier *mk_spec); | |
572 | ||
218d921b EB |
573 | int fscrypt_get_test_dummy_key_identifier( |
574 | u8 key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]); | |
cdeb21da | 575 | |
097d7c1f EB |
576 | int fscrypt_add_test_dummy_key(struct super_block *sb, |
577 | struct fscrypt_key_specifier *key_spec); | |
578 | ||
60700902 EB |
579 | int fscrypt_verify_key_added(struct super_block *sb, |
580 | const u8 identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]); | |
5ab7189a | 581 | |
60700902 | 582 | int __init fscrypt_init_keyring(void); |
22d94f49 | 583 | |
feed8258 | 584 | /* keysetup.c */ |
8094c3ce EB |
585 | |
586 | struct fscrypt_mode { | |
587 | const char *friendly_name; | |
588 | const char *cipher_str; | |
7f595d6a EB |
589 | int keysize; /* key size in bytes */ |
590 | int security_strength; /* security strength in bytes */ | |
591 | int ivsize; /* IV size in bytes */ | |
a7a5bc5f EB |
592 | int logged_cryptoapi_impl; |
593 | int logged_blk_crypto_native; | |
594 | int logged_blk_crypto_fallback; | |
5fee3609 | 595 | enum blk_crypto_mode_num blk_crypto_mode; |
8094c3ce EB |
596 | }; |
597 | ||
85af90e5 | 598 | extern struct fscrypt_mode fscrypt_modes[]; |
3ec4f2a6 | 599 | |
5fee3609 ST |
600 | int fscrypt_prepare_key(struct fscrypt_prepared_key *prep_key, |
601 | const u8 *raw_key, const struct fscrypt_info *ci); | |
602 | ||
22e9947a EB |
603 | void fscrypt_destroy_prepared_key(struct super_block *sb, |
604 | struct fscrypt_prepared_key *prep_key); | |
0109ce76 | 605 | |
60700902 | 606 | int fscrypt_set_per_file_enc_key(struct fscrypt_info *ci, const u8 *raw_key); |
0109ce76 | 607 | |
60700902 EB |
608 | int fscrypt_derive_dirhash_key(struct fscrypt_info *ci, |
609 | const struct fscrypt_master_key *mk); | |
aa408f83 | 610 | |
a992b20c EB |
611 | void fscrypt_hash_inode_number(struct fscrypt_info *ci, |
612 | const struct fscrypt_master_key *mk); | |
613 | ||
a14d0b67 | 614 | int fscrypt_get_encryption_info(struct inode *inode, bool allow_unsupported); |
5b421f08 | 615 | |
de3cdc6e EB |
616 | /** |
617 | * fscrypt_require_key() - require an inode's encryption key | |
618 | * @inode: the inode we need the key for | |
619 | * | |
620 | * If the inode is encrypted, set up its encryption key if not already done. | |
621 | * Then require that the key be present and return -ENOKEY otherwise. | |
622 | * | |
623 | * No locks are needed, and the key will live as long as the struct inode --- so | |
624 | * it won't go away from under you. | |
625 | * | |
626 | * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code | |
627 | * if a problem occurred while setting up the encryption key. | |
628 | */ | |
629 | static inline int fscrypt_require_key(struct inode *inode) | |
630 | { | |
631 | if (IS_ENCRYPTED(inode)) { | |
a14d0b67 | 632 | int err = fscrypt_get_encryption_info(inode, false); |
de3cdc6e EB |
633 | |
634 | if (err) | |
635 | return err; | |
636 | if (!fscrypt_has_encryption_key(inode)) | |
637 | return -ENOKEY; | |
638 | } | |
639 | return 0; | |
640 | } | |
641 | ||
0109ce76 EB |
642 | /* keysetup_v1.c */ |
643 | ||
60700902 | 644 | void fscrypt_put_direct_key(struct fscrypt_direct_key *dk); |
0109ce76 | 645 | |
60700902 EB |
646 | int fscrypt_setup_v1_file_key(struct fscrypt_info *ci, |
647 | const u8 *raw_master_key); | |
648 | ||
649 | int fscrypt_setup_v1_file_key_via_subscribed_keyrings(struct fscrypt_info *ci); | |
0109ce76 | 650 | |
5dae460c EB |
651 | /* policy.c */ |
652 | ||
60700902 EB |
653 | bool fscrypt_policies_equal(const union fscrypt_policy *policy1, |
654 | const union fscrypt_policy *policy2); | |
bfb9700b EB |
655 | int fscrypt_policy_to_key_spec(const union fscrypt_policy *policy, |
656 | struct fscrypt_key_specifier *key_spec); | |
60e463f0 | 657 | const union fscrypt_policy *fscrypt_get_dummy_policy(struct super_block *sb); |
60700902 EB |
658 | bool fscrypt_supported_policy(const union fscrypt_policy *policy_u, |
659 | const struct inode *inode); | |
660 | int fscrypt_policy_from_context(union fscrypt_policy *policy_u, | |
661 | const union fscrypt_context *ctx_u, | |
662 | int ctx_size); | |
ac4acb1f | 663 | const union fscrypt_policy *fscrypt_policy_to_inherit(struct inode *dir); |
0109ce76 | 664 | |
3325bea5 | 665 | #endif /* _FSCRYPT_PRIVATE_H */ |