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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; | |
5b118884 EB |
50 | u8 log2_data_unit_size; |
51 | u8 __reserved[3]; | |
5dae460c | 52 | u8 master_key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]; |
1d6217a4 | 53 | u8 nonce[FSCRYPT_FILE_NONCE_SIZE]; |
5dae460c EB |
54 | }; |
55 | ||
d2fe9754 | 56 | /* |
5dae460c EB |
57 | * fscrypt_context - the encryption context of an inode |
58 | * | |
59 | * This is the on-disk equivalent of an fscrypt_policy, stored alongside each | |
60 | * encrypted file usually in a hidden extended attribute. It contains the | |
61 | * fields from the fscrypt_policy, in order to identify the encryption algorithm | |
62 | * and key with which the file is encrypted. It also contains a nonce that was | |
63 | * randomly generated by fscrypt itself; this is used as KDF input or as a tweak | |
64 | * to cause different files to be encrypted differently. | |
65 | */ | |
66 | union fscrypt_context { | |
67 | u8 version; | |
68 | struct fscrypt_context_v1 v1; | |
69 | struct fscrypt_context_v2 v2; | |
70 | }; | |
71 | ||
72 | /* | |
73 | * Return the size expected for the given fscrypt_context based on its version | |
74 | * number, or 0 if the context version is unrecognized. | |
75 | */ | |
76 | static inline int fscrypt_context_size(const union fscrypt_context *ctx) | |
77 | { | |
78 | switch (ctx->version) { | |
79 | case FSCRYPT_CONTEXT_V1: | |
80 | BUILD_BUG_ON(sizeof(ctx->v1) != 28); | |
81 | return sizeof(ctx->v1); | |
82 | case FSCRYPT_CONTEXT_V2: | |
83 | BUILD_BUG_ON(sizeof(ctx->v2) != 40); | |
84 | return sizeof(ctx->v2); | |
85 | } | |
86 | return 0; | |
87 | } | |
88 | ||
e98ad464 EB |
89 | /* Check whether an fscrypt_context has a recognized version number and size */ |
90 | static inline bool fscrypt_context_is_valid(const union fscrypt_context *ctx, | |
91 | int ctx_size) | |
92 | { | |
93 | return ctx_size >= 1 && ctx_size == fscrypt_context_size(ctx); | |
94 | } | |
95 | ||
96 | /* Retrieve the context's nonce, assuming the context was already validated */ | |
97 | static inline const u8 *fscrypt_context_nonce(const union fscrypt_context *ctx) | |
98 | { | |
99 | switch (ctx->version) { | |
100 | case FSCRYPT_CONTEXT_V1: | |
101 | return ctx->v1.nonce; | |
102 | case FSCRYPT_CONTEXT_V2: | |
103 | return ctx->v2.nonce; | |
104 | } | |
41b2ad80 | 105 | WARN_ON_ONCE(1); |
e98ad464 EB |
106 | return NULL; |
107 | } | |
108 | ||
5dae460c EB |
109 | union fscrypt_policy { |
110 | u8 version; | |
111 | struct fscrypt_policy_v1 v1; | |
112 | struct fscrypt_policy_v2 v2; | |
113 | }; | |
114 | ||
115 | /* | |
116 | * Return the size expected for the given fscrypt_policy based on its version | |
117 | * number, or 0 if the policy version is unrecognized. | |
118 | */ | |
119 | static inline int fscrypt_policy_size(const union fscrypt_policy *policy) | |
120 | { | |
121 | switch (policy->version) { | |
122 | case FSCRYPT_POLICY_V1: | |
123 | return sizeof(policy->v1); | |
124 | case FSCRYPT_POLICY_V2: | |
125 | return sizeof(policy->v2); | |
126 | } | |
127 | return 0; | |
128 | } | |
129 | ||
130 | /* Return the contents encryption mode of a valid encryption policy */ | |
131 | static inline u8 | |
132 | fscrypt_policy_contents_mode(const union fscrypt_policy *policy) | |
133 | { | |
134 | switch (policy->version) { | |
135 | case FSCRYPT_POLICY_V1: | |
136 | return policy->v1.contents_encryption_mode; | |
137 | case FSCRYPT_POLICY_V2: | |
138 | return policy->v2.contents_encryption_mode; | |
139 | } | |
140 | BUG(); | |
141 | } | |
142 | ||
143 | /* Return the filenames encryption mode of a valid encryption policy */ | |
144 | static inline u8 | |
145 | fscrypt_policy_fnames_mode(const union fscrypt_policy *policy) | |
146 | { | |
147 | switch (policy->version) { | |
148 | case FSCRYPT_POLICY_V1: | |
149 | return policy->v1.filenames_encryption_mode; | |
150 | case FSCRYPT_POLICY_V2: | |
151 | return policy->v2.filenames_encryption_mode; | |
152 | } | |
153 | BUG(); | |
154 | } | |
155 | ||
156 | /* Return the flags (FSCRYPT_POLICY_FLAG*) of a valid encryption policy */ | |
157 | static inline u8 | |
158 | fscrypt_policy_flags(const union fscrypt_policy *policy) | |
159 | { | |
160 | switch (policy->version) { | |
161 | case FSCRYPT_POLICY_V1: | |
162 | return policy->v1.flags; | |
163 | case FSCRYPT_POLICY_V2: | |
164 | return policy->v2.flags; | |
165 | } | |
166 | BUG(); | |
167 | } | |
168 | ||
5b118884 EB |
169 | static inline int |
170 | fscrypt_policy_v2_du_bits(const struct fscrypt_policy_v2 *policy, | |
171 | const struct inode *inode) | |
172 | { | |
173 | return policy->log2_data_unit_size ?: inode->i_blkbits; | |
174 | } | |
175 | ||
176 | static inline int | |
177 | fscrypt_policy_du_bits(const union fscrypt_policy *policy, | |
178 | const struct inode *inode) | |
179 | { | |
180 | switch (policy->version) { | |
181 | case FSCRYPT_POLICY_V1: | |
182 | return inode->i_blkbits; | |
183 | case FSCRYPT_POLICY_V2: | |
184 | return fscrypt_policy_v2_du_bits(&policy->v2, inode); | |
185 | } | |
186 | BUG(); | |
187 | } | |
188 | ||
d2fe9754 | 189 | /* |
0eaab5b1 EB |
190 | * For encrypted symlinks, the ciphertext length is stored at the beginning |
191 | * of the string in little-endian format. | |
192 | */ | |
193 | struct fscrypt_symlink_data { | |
194 | __le16 len; | |
d617ef03 | 195 | char encrypted_path[]; |
0eaab5b1 EB |
196 | } __packed; |
197 | ||
5fee3609 ST |
198 | /** |
199 | * struct fscrypt_prepared_key - a key prepared for actual encryption/decryption | |
200 | * @tfm: crypto API transform object | |
201 | * @blk_key: key for blk-crypto | |
202 | * | |
203 | * Normally only one of the fields will be non-NULL. | |
204 | */ | |
205 | struct fscrypt_prepared_key { | |
206 | struct crypto_skcipher *tfm; | |
207 | #ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT | |
22e9947a | 208 | struct blk_crypto_key *blk_key; |
5fee3609 ST |
209 | #endif |
210 | }; | |
211 | ||
cc4e0df0 | 212 | /* |
3e7807d5 | 213 | * fscrypt_inode_info - the "encryption key" for an inode |
8094c3ce EB |
214 | * |
215 | * When an encrypted file's key is made available, an instance of this struct is | |
216 | * allocated and stored in ->i_crypt_info. Once created, it remains until the | |
217 | * inode is evicted. | |
cc4e0df0 | 218 | */ |
3e7807d5 | 219 | struct fscrypt_inode_info { |
8094c3ce | 220 | |
5fee3609 ST |
221 | /* The key in a form prepared for actual encryption/decryption */ |
222 | struct fscrypt_prepared_key ci_enc_key; | |
8094c3ce | 223 | |
3e7807d5 | 224 | /* True if ci_enc_key should be freed when this struct is freed */ |
8c62f31e | 225 | u8 ci_owns_key : 1; |
b103fb76 | 226 | |
5fee3609 ST |
227 | #ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT |
228 | /* | |
229 | * True if this inode will use inline encryption (blk-crypto) instead of | |
230 | * the traditional filesystem-layer encryption. | |
231 | */ | |
8c62f31e | 232 | u8 ci_inlinecrypt : 1; |
5fee3609 ST |
233 | #endif |
234 | ||
8c62f31e EB |
235 | /* True if ci_dirhash_key is initialized */ |
236 | u8 ci_dirhash_key_initialized : 1; | |
237 | ||
5b118884 EB |
238 | /* |
239 | * log2 of the data unit size (granularity of contents encryption) of | |
240 | * this file. This is computable from ci_policy and ci_inode but is | |
241 | * cached here for efficiency. Only used for regular files. | |
242 | */ | |
243 | u8 ci_data_unit_bits; | |
244 | ||
245 | /* Cached value: log2 of number of data units per FS block */ | |
246 | u8 ci_data_units_per_block_bits; | |
247 | ||
8c62f31e EB |
248 | /* Hashed inode number. Only set for IV_INO_LBLK_32 */ |
249 | u32 ci_hashed_ino; | |
250 | ||
8094c3ce | 251 | /* |
5dae460c EB |
252 | * Encryption mode used for this inode. It corresponds to either the |
253 | * contents or filenames encryption mode, depending on the inode type. | |
8094c3ce EB |
254 | */ |
255 | struct fscrypt_mode *ci_mode; | |
256 | ||
59dc6a8e EB |
257 | /* Back-pointer to the inode */ |
258 | struct inode *ci_inode; | |
259 | ||
b1c0ec35 EB |
260 | /* |
261 | * The master key with which this inode was unlocked (decrypted). This | |
262 | * will be NULL if the master key was found in a process-subscribed | |
263 | * keyring rather than in the filesystem-level keyring. | |
264 | */ | |
d7e7b9af | 265 | struct fscrypt_master_key *ci_master_key; |
b1c0ec35 EB |
266 | |
267 | /* | |
268 | * Link in list of inodes that were unlocked with the master key. | |
269 | * Only used when ->ci_master_key is set. | |
270 | */ | |
271 | struct list_head ci_master_key_link; | |
272 | ||
8094c3ce | 273 | /* |
a828daab | 274 | * If non-NULL, then encryption is done using the master key directly |
5fee3609 | 275 | * and ci_enc_key will equal ci_direct_key->dk_key. |
8094c3ce | 276 | */ |
a828daab | 277 | struct fscrypt_direct_key *ci_direct_key; |
8094c3ce | 278 | |
aa408f83 DR |
279 | /* |
280 | * This inode's hash key for filenames. This is a 128-bit SipHash-2-4 | |
281 | * key. This is only set for directories that use a keyed dirhash over | |
282 | * the plaintext filenames -- currently just casefolded directories. | |
283 | */ | |
284 | siphash_key_t ci_dirhash_key; | |
aa408f83 | 285 | |
5dae460c EB |
286 | /* The encryption policy used by this inode */ |
287 | union fscrypt_policy ci_policy; | |
288 | ||
289 | /* This inode's nonce, copied from the fscrypt_context */ | |
1d6217a4 | 290 | u8 ci_nonce[FSCRYPT_FILE_NONCE_SIZE]; |
cc4e0df0 TT |
291 | }; |
292 | ||
58ae7468 RW |
293 | typedef enum { |
294 | FS_DECRYPT = 0, | |
295 | FS_ENCRYPT, | |
296 | } fscrypt_direction_t; | |
297 | ||
b98701df | 298 | /* crypto.c */ |
3e7807d5 | 299 | extern struct kmem_cache *fscrypt_inode_info_cachep; |
83e57e47 | 300 | int fscrypt_initialize(struct super_block *sb); |
3e7807d5 | 301 | int fscrypt_crypt_data_unit(const struct fscrypt_inode_info *ci, |
5b118884 EB |
302 | fscrypt_direction_t rw, u64 index, |
303 | struct page *src_page, struct page *dest_page, | |
304 | unsigned int len, unsigned int offs, | |
305 | gfp_t gfp_flags); | |
60700902 EB |
306 | struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags); |
307 | ||
308 | void __printf(3, 4) __cold | |
886da8b3 | 309 | fscrypt_msg(const struct inode *inode, const char *level, const char *fmt, ...); |
544d08fd | 310 | |
886da8b3 EB |
311 | #define fscrypt_warn(inode, fmt, ...) \ |
312 | fscrypt_msg((inode), KERN_WARNING, fmt, ##__VA_ARGS__) | |
313 | #define fscrypt_err(inode, fmt, ...) \ | |
314 | fscrypt_msg((inode), KERN_ERR, fmt, ##__VA_ARGS__) | |
544d08fd | 315 | |
8094c3ce EB |
316 | #define FSCRYPT_MAX_IV_SIZE 32 |
317 | ||
318 | union fscrypt_iv { | |
319 | struct { | |
5b118884 EB |
320 | /* zero-based index of data unit within the file */ |
321 | __le64 index; | |
8094c3ce EB |
322 | |
323 | /* per-file nonce; only set in DIRECT_KEY mode */ | |
1d6217a4 | 324 | u8 nonce[FSCRYPT_FILE_NONCE_SIZE]; |
8094c3ce EB |
325 | }; |
326 | u8 raw[FSCRYPT_MAX_IV_SIZE]; | |
5fee3609 | 327 | __le64 dun[FSCRYPT_MAX_IV_SIZE / sizeof(__le64)]; |
8094c3ce EB |
328 | }; |
329 | ||
5b118884 | 330 | void fscrypt_generate_iv(union fscrypt_iv *iv, u64 index, |
3e7807d5 | 331 | const struct fscrypt_inode_info *ci); |
8094c3ce | 332 | |
f0904e8b | 333 | /* |
5b118884 EB |
334 | * Return the number of bits used by the maximum file data unit index that is |
335 | * possible on the given filesystem, using the given log2 data unit size. | |
f0904e8b EB |
336 | */ |
337 | static inline int | |
5b118884 | 338 | fscrypt_max_file_dun_bits(const struct super_block *sb, int du_bits) |
f0904e8b | 339 | { |
5b118884 | 340 | return fls64(sb->s_maxbytes - 1) - du_bits; |
f0904e8b EB |
341 | } |
342 | ||
76e81d6d | 343 | /* fname.c */ |
d3e94fdc JL |
344 | bool __fscrypt_fname_encrypted_size(const union fscrypt_policy *policy, |
345 | u32 orig_len, u32 max_len, | |
346 | u32 *encrypted_len_ret); | |
76e81d6d | 347 | |
c1144c9b | 348 | /* hkdf.c */ |
c1144c9b EB |
349 | struct fscrypt_hkdf { |
350 | struct crypto_shash *hmac_tfm; | |
351 | }; | |
352 | ||
60700902 EB |
353 | int fscrypt_init_hkdf(struct fscrypt_hkdf *hkdf, const u8 *master_key, |
354 | unsigned int master_key_size); | |
c1144c9b | 355 | |
5dae460c EB |
356 | /* |
357 | * The list of contexts in which fscrypt uses HKDF. These values are used as | |
358 | * the first byte of the HKDF application-specific info string to guarantee that | |
359 | * info strings are never repeated between contexts. This ensures that all HKDF | |
360 | * outputs are unique and cryptographically isolated, i.e. knowledge of one | |
361 | * output doesn't reveal another. | |
362 | */ | |
e455de31 EB |
363 | #define HKDF_CONTEXT_KEY_IDENTIFIER 1 /* info=<empty> */ |
364 | #define HKDF_CONTEXT_PER_FILE_ENC_KEY 2 /* info=file_nonce */ | |
365 | #define HKDF_CONTEXT_DIRECT_KEY 3 /* info=mode_num */ | |
366 | #define HKDF_CONTEXT_IV_INO_LBLK_64_KEY 4 /* info=mode_num||fs_uuid */ | |
367 | #define HKDF_CONTEXT_DIRHASH_KEY 5 /* info=file_nonce */ | |
368 | #define HKDF_CONTEXT_IV_INO_LBLK_32_KEY 6 /* info=mode_num||fs_uuid */ | |
369 | #define HKDF_CONTEXT_INODE_HASH_KEY 7 /* info=<empty> */ | |
5dae460c | 370 | |
60700902 EB |
371 | int fscrypt_hkdf_expand(const struct fscrypt_hkdf *hkdf, u8 context, |
372 | const u8 *info, unsigned int infolen, | |
373 | u8 *okm, unsigned int okmlen); | |
c1144c9b | 374 | |
60700902 | 375 | void fscrypt_destroy_hkdf(struct fscrypt_hkdf *hkdf); |
c1144c9b | 376 | |
5fee3609 ST |
377 | /* inline_crypt.c */ |
378 | #ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT | |
3e7807d5 | 379 | int fscrypt_select_encryption_impl(struct fscrypt_inode_info *ci); |
5fee3609 ST |
380 | |
381 | static inline bool | |
3e7807d5 | 382 | fscrypt_using_inline_encryption(const struct fscrypt_inode_info *ci) |
5fee3609 ST |
383 | { |
384 | return ci->ci_inlinecrypt; | |
385 | } | |
386 | ||
387 | int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key, | |
388 | const u8 *raw_key, | |
3e7807d5 | 389 | const struct fscrypt_inode_info *ci); |
5fee3609 | 390 | |
22e9947a EB |
391 | void fscrypt_destroy_inline_crypt_key(struct super_block *sb, |
392 | struct fscrypt_prepared_key *prep_key); | |
5fee3609 ST |
393 | |
394 | /* | |
395 | * Check whether the crypto transform or blk-crypto key has been allocated in | |
396 | * @prep_key, depending on which encryption implementation the file will use. | |
397 | */ | |
398 | static inline bool | |
399 | fscrypt_is_key_prepared(struct fscrypt_prepared_key *prep_key, | |
3e7807d5 | 400 | const struct fscrypt_inode_info *ci) |
5fee3609 ST |
401 | { |
402 | /* | |
97c6327f EB |
403 | * The two smp_load_acquire()'s here pair with the smp_store_release()'s |
404 | * in fscrypt_prepare_inline_crypt_key() and fscrypt_prepare_key(). | |
405 | * I.e., in some cases (namely, if this prep_key is a per-mode | |
406 | * encryption key) another task can publish blk_key or tfm concurrently, | |
407 | * executing a RELEASE barrier. We need to use smp_load_acquire() here | |
408 | * to safely ACQUIRE the memory the other task published. | |
5fee3609 ST |
409 | */ |
410 | if (fscrypt_using_inline_encryption(ci)) | |
97c6327f EB |
411 | return smp_load_acquire(&prep_key->blk_key) != NULL; |
412 | return smp_load_acquire(&prep_key->tfm) != NULL; | |
5fee3609 ST |
413 | } |
414 | ||
415 | #else /* CONFIG_FS_ENCRYPTION_INLINE_CRYPT */ | |
416 | ||
3e7807d5 | 417 | static inline int fscrypt_select_encryption_impl(struct fscrypt_inode_info *ci) |
5fee3609 ST |
418 | { |
419 | return 0; | |
420 | } | |
421 | ||
422 | static inline bool | |
3e7807d5 | 423 | fscrypt_using_inline_encryption(const struct fscrypt_inode_info *ci) |
5fee3609 ST |
424 | { |
425 | return false; | |
426 | } | |
427 | ||
428 | static inline int | |
429 | fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key, | |
430 | const u8 *raw_key, | |
3e7807d5 | 431 | const struct fscrypt_inode_info *ci) |
5fee3609 | 432 | { |
41b2ad80 | 433 | WARN_ON_ONCE(1); |
5fee3609 ST |
434 | return -EOPNOTSUPP; |
435 | } | |
436 | ||
437 | static inline void | |
22e9947a EB |
438 | fscrypt_destroy_inline_crypt_key(struct super_block *sb, |
439 | struct fscrypt_prepared_key *prep_key) | |
5fee3609 ST |
440 | { |
441 | } | |
442 | ||
443 | static inline bool | |
444 | fscrypt_is_key_prepared(struct fscrypt_prepared_key *prep_key, | |
3e7807d5 | 445 | const struct fscrypt_inode_info *ci) |
5fee3609 | 446 | { |
97c6327f | 447 | return smp_load_acquire(&prep_key->tfm) != NULL; |
5fee3609 ST |
448 | } |
449 | #endif /* !CONFIG_FS_ENCRYPTION_INLINE_CRYPT */ | |
450 | ||
22d94f49 EB |
451 | /* keyring.c */ |
452 | ||
453 | /* | |
454 | * fscrypt_master_key_secret - secret key material of an in-use master key | |
455 | */ | |
456 | struct fscrypt_master_key_secret { | |
457 | ||
5dae460c EB |
458 | /* |
459 | * For v2 policy keys: HKDF context keyed by this master key. | |
460 | * For v1 policy keys: not set (hkdf.hmac_tfm == NULL). | |
461 | */ | |
462 | struct fscrypt_hkdf hkdf; | |
463 | ||
b7e072f9 EB |
464 | /* |
465 | * Size of the raw key in bytes. This remains set even if ->raw was | |
466 | * zeroized due to no longer being needed. I.e. we still remember the | |
467 | * size of the key even if we don't need to remember the key itself. | |
468 | */ | |
22d94f49 EB |
469 | u32 size; |
470 | ||
5dae460c | 471 | /* For v1 policy keys: the raw key. Wiped for v2 policy keys. */ |
22d94f49 EB |
472 | u8 raw[FSCRYPT_MAX_KEY_SIZE]; |
473 | ||
474 | } __randomize_layout; | |
475 | ||
476 | /* | |
477 | * fscrypt_master_key - an in-use master key | |
478 | * | |
479 | * This represents a master encryption key which has been added to the | |
15baf554 EB |
480 | * filesystem. There are three high-level states that a key can be in: |
481 | * | |
482 | * FSCRYPT_KEY_STATUS_PRESENT | |
483 | * Key is fully usable; it can be used to unlock inodes that are encrypted | |
484 | * with it (this includes being able to create new inodes). ->mk_present | |
485 | * indicates whether the key is in this state. ->mk_secret exists, the key | |
486 | * is in the keyring, and ->mk_active_refs > 0 due to ->mk_present. | |
487 | * | |
488 | * FSCRYPT_KEY_STATUS_INCOMPLETELY_REMOVED | |
489 | * Removal of this key has been initiated, but some inodes that were | |
490 | * unlocked with it are still in-use. Like ABSENT, ->mk_secret is wiped, | |
491 | * and the key can no longer be used to unlock inodes. Unlike ABSENT, the | |
492 | * key is still in the keyring; ->mk_decrypted_inodes is nonempty; and | |
493 | * ->mk_active_refs > 0, being equal to the size of ->mk_decrypted_inodes. | |
494 | * | |
495 | * This state transitions to ABSENT if ->mk_decrypted_inodes becomes empty, | |
496 | * or to PRESENT if FS_IOC_ADD_ENCRYPTION_KEY is called again for this key. | |
497 | * | |
498 | * FSCRYPT_KEY_STATUS_ABSENT | |
499 | * Key is fully removed. The key is no longer in the keyring, | |
500 | * ->mk_decrypted_inodes is empty, ->mk_active_refs == 0, ->mk_secret is | |
501 | * wiped, and the key can no longer be used to unlock inodes. | |
22d94f49 EB |
502 | */ |
503 | struct fscrypt_master_key { | |
504 | ||
d7e7b9af | 505 | /* |
02aef422 | 506 | * Link in ->s_master_keys->key_hashtable. |
d7e7b9af EB |
507 | * Only valid if ->mk_active_refs > 0. |
508 | */ | |
509 | struct hlist_node mk_node; | |
510 | ||
15baf554 | 511 | /* Semaphore that protects ->mk_secret, ->mk_users, and ->mk_present */ |
d7e7b9af EB |
512 | struct rw_semaphore mk_sem; |
513 | ||
514 | /* | |
515 | * Active and structural reference counts. An active ref guarantees | |
516 | * that the struct continues to exist, continues to be in the keyring | |
02aef422 | 517 | * ->s_master_keys, and that any embedded subkeys (e.g. |
d7e7b9af EB |
518 | * ->mk_direct_keys) that have been prepared continue to exist. |
519 | * A structural ref only guarantees that the struct continues to exist. | |
520 | * | |
15baf554 EB |
521 | * There is one active ref associated with ->mk_present being true, and |
522 | * one active ref for each inode in ->mk_decrypted_inodes. | |
d7e7b9af EB |
523 | * |
524 | * There is one structural ref associated with the active refcount being | |
525 | * nonzero. Finding a key in the keyring also takes a structural ref, | |
526 | * which is then held temporarily while the key is operated on. | |
527 | */ | |
528 | refcount_t mk_active_refs; | |
529 | refcount_t mk_struct_refs; | |
530 | ||
531 | struct rcu_head mk_rcu_head; | |
532 | ||
b1c0ec35 | 533 | /* |
15baf554 EB |
534 | * The secret key material. Wiped as soon as it is no longer needed; |
535 | * for details, see the fscrypt_master_key struct comment. | |
b1c0ec35 | 536 | * |
15baf554 | 537 | * Locking: protected by ->mk_sem. |
b1c0ec35 | 538 | */ |
22d94f49 EB |
539 | struct fscrypt_master_key_secret mk_secret; |
540 | ||
5dae460c EB |
541 | /* |
542 | * For v1 policy keys: an arbitrary key descriptor which was assigned by | |
543 | * userspace (->descriptor). | |
544 | * | |
545 | * For v2 policy keys: a cryptographic hash of this key (->identifier). | |
546 | */ | |
22d94f49 EB |
547 | struct fscrypt_key_specifier mk_spec; |
548 | ||
23c688b5 EB |
549 | /* |
550 | * Keyring which contains a key of type 'key_type_fscrypt_user' for each | |
551 | * user who has added this key. Normally each key will be added by just | |
552 | * one user, but it's possible that multiple users share a key, and in | |
553 | * that case we need to keep track of those users so that one user can't | |
554 | * remove the key before the others want it removed too. | |
555 | * | |
556 | * This is NULL for v1 policy keys; those can only be added by root. | |
557 | * | |
d7e7b9af EB |
558 | * Locking: protected by ->mk_sem. (We don't just rely on the keyrings |
559 | * subsystem semaphore ->mk_users->sem, as we need support for atomic | |
15baf554 | 560 | * search+insert along with proper synchronization with other fields.) |
23c688b5 EB |
561 | */ |
562 | struct key *mk_users; | |
563 | ||
b1c0ec35 EB |
564 | /* |
565 | * List of inodes that were unlocked using this key. This allows the | |
566 | * inodes to be evicted efficiently if the key is removed. | |
567 | */ | |
568 | struct list_head mk_decrypted_inodes; | |
569 | spinlock_t mk_decrypted_inodes_lock; | |
570 | ||
b103fb76 | 571 | /* |
e3b1078b EB |
572 | * Per-mode encryption keys for the various types of encryption policies |
573 | * that use them. Allocated and derived on-demand. | |
b103fb76 | 574 | */ |
3ceb6543 EB |
575 | struct fscrypt_prepared_key mk_direct_keys[FSCRYPT_MODE_MAX + 1]; |
576 | struct fscrypt_prepared_key mk_iv_ino_lblk_64_keys[FSCRYPT_MODE_MAX + 1]; | |
577 | struct fscrypt_prepared_key mk_iv_ino_lblk_32_keys[FSCRYPT_MODE_MAX + 1]; | |
e3b1078b EB |
578 | |
579 | /* Hash key for inode numbers. Initialized only when needed. */ | |
580 | siphash_key_t mk_ino_hash_key; | |
581 | bool mk_ino_hash_key_initialized; | |
5dae460c | 582 | |
b1c0ec35 | 583 | /* |
15baf554 EB |
584 | * Whether this key is in the "present" state, i.e. fully usable. For |
585 | * details, see the fscrypt_master_key struct comment. | |
586 | * | |
587 | * Locking: protected by ->mk_sem, but can be read locklessly using | |
588 | * READ_ONCE(). Writers must use WRITE_ONCE() when concurrent readers | |
589 | * are possible. | |
b1c0ec35 | 590 | */ |
15baf554 EB |
591 | bool mk_present; |
592 | ||
593 | } __randomize_layout; | |
b1c0ec35 | 594 | |
22d94f49 EB |
595 | static inline const char *master_key_spec_type( |
596 | const struct fscrypt_key_specifier *spec) | |
597 | { | |
598 | switch (spec->type) { | |
599 | case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR: | |
600 | return "descriptor"; | |
5dae460c EB |
601 | case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER: |
602 | return "identifier"; | |
22d94f49 EB |
603 | } |
604 | return "[unknown]"; | |
605 | } | |
606 | ||
607 | static inline int master_key_spec_len(const struct fscrypt_key_specifier *spec) | |
608 | { | |
609 | switch (spec->type) { | |
610 | case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR: | |
611 | return FSCRYPT_KEY_DESCRIPTOR_SIZE; | |
5dae460c EB |
612 | case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER: |
613 | return FSCRYPT_KEY_IDENTIFIER_SIZE; | |
22d94f49 EB |
614 | } |
615 | return 0; | |
616 | } | |
617 | ||
d7e7b9af EB |
618 | void fscrypt_put_master_key(struct fscrypt_master_key *mk); |
619 | ||
02aef422 EB |
620 | void fscrypt_put_master_key_activeref(struct super_block *sb, |
621 | struct fscrypt_master_key *mk); | |
d7e7b9af EB |
622 | |
623 | struct fscrypt_master_key * | |
22d94f49 EB |
624 | fscrypt_find_master_key(struct super_block *sb, |
625 | const struct fscrypt_key_specifier *mk_spec); | |
626 | ||
218d921b EB |
627 | int fscrypt_get_test_dummy_key_identifier( |
628 | u8 key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]); | |
cdeb21da | 629 | |
097d7c1f EB |
630 | int fscrypt_add_test_dummy_key(struct super_block *sb, |
631 | struct fscrypt_key_specifier *key_spec); | |
632 | ||
60700902 EB |
633 | int fscrypt_verify_key_added(struct super_block *sb, |
634 | const u8 identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]); | |
5ab7189a | 635 | |
60700902 | 636 | int __init fscrypt_init_keyring(void); |
22d94f49 | 637 | |
feed8258 | 638 | /* keysetup.c */ |
8094c3ce EB |
639 | |
640 | struct fscrypt_mode { | |
641 | const char *friendly_name; | |
642 | const char *cipher_str; | |
7f595d6a EB |
643 | int keysize; /* key size in bytes */ |
644 | int security_strength; /* security strength in bytes */ | |
645 | int ivsize; /* IV size in bytes */ | |
a7a5bc5f EB |
646 | int logged_cryptoapi_impl; |
647 | int logged_blk_crypto_native; | |
648 | int logged_blk_crypto_fallback; | |
5fee3609 | 649 | enum blk_crypto_mode_num blk_crypto_mode; |
8094c3ce EB |
650 | }; |
651 | ||
85af90e5 | 652 | extern struct fscrypt_mode fscrypt_modes[]; |
3ec4f2a6 | 653 | |
5fee3609 | 654 | int fscrypt_prepare_key(struct fscrypt_prepared_key *prep_key, |
3e7807d5 | 655 | const u8 *raw_key, const struct fscrypt_inode_info *ci); |
5fee3609 | 656 | |
22e9947a EB |
657 | void fscrypt_destroy_prepared_key(struct super_block *sb, |
658 | struct fscrypt_prepared_key *prep_key); | |
0109ce76 | 659 | |
3e7807d5 JB |
660 | int fscrypt_set_per_file_enc_key(struct fscrypt_inode_info *ci, |
661 | const u8 *raw_key); | |
0109ce76 | 662 | |
3e7807d5 | 663 | int fscrypt_derive_dirhash_key(struct fscrypt_inode_info *ci, |
60700902 | 664 | const struct fscrypt_master_key *mk); |
aa408f83 | 665 | |
3e7807d5 | 666 | void fscrypt_hash_inode_number(struct fscrypt_inode_info *ci, |
a992b20c EB |
667 | const struct fscrypt_master_key *mk); |
668 | ||
a14d0b67 | 669 | int fscrypt_get_encryption_info(struct inode *inode, bool allow_unsupported); |
5b421f08 | 670 | |
de3cdc6e EB |
671 | /** |
672 | * fscrypt_require_key() - require an inode's encryption key | |
673 | * @inode: the inode we need the key for | |
674 | * | |
675 | * If the inode is encrypted, set up its encryption key if not already done. | |
676 | * Then require that the key be present and return -ENOKEY otherwise. | |
677 | * | |
678 | * No locks are needed, and the key will live as long as the struct inode --- so | |
679 | * it won't go away from under you. | |
680 | * | |
681 | * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code | |
682 | * if a problem occurred while setting up the encryption key. | |
683 | */ | |
684 | static inline int fscrypt_require_key(struct inode *inode) | |
685 | { | |
686 | if (IS_ENCRYPTED(inode)) { | |
a14d0b67 | 687 | int err = fscrypt_get_encryption_info(inode, false); |
de3cdc6e EB |
688 | |
689 | if (err) | |
690 | return err; | |
691 | if (!fscrypt_has_encryption_key(inode)) | |
692 | return -ENOKEY; | |
693 | } | |
694 | return 0; | |
695 | } | |
696 | ||
0109ce76 EB |
697 | /* keysetup_v1.c */ |
698 | ||
60700902 | 699 | void fscrypt_put_direct_key(struct fscrypt_direct_key *dk); |
0109ce76 | 700 | |
3e7807d5 | 701 | int fscrypt_setup_v1_file_key(struct fscrypt_inode_info *ci, |
60700902 EB |
702 | const u8 *raw_master_key); |
703 | ||
3e7807d5 JB |
704 | int fscrypt_setup_v1_file_key_via_subscribed_keyrings( |
705 | struct fscrypt_inode_info *ci); | |
0109ce76 | 706 | |
5dae460c EB |
707 | /* policy.c */ |
708 | ||
60700902 EB |
709 | bool fscrypt_policies_equal(const union fscrypt_policy *policy1, |
710 | const union fscrypt_policy *policy2); | |
bfb9700b EB |
711 | int fscrypt_policy_to_key_spec(const union fscrypt_policy *policy, |
712 | struct fscrypt_key_specifier *key_spec); | |
60e463f0 | 713 | const union fscrypt_policy *fscrypt_get_dummy_policy(struct super_block *sb); |
60700902 EB |
714 | bool fscrypt_supported_policy(const union fscrypt_policy *policy_u, |
715 | const struct inode *inode); | |
716 | int fscrypt_policy_from_context(union fscrypt_policy *policy_u, | |
717 | const union fscrypt_context *ctx_u, | |
718 | int ctx_size); | |
ac4acb1f | 719 | const union fscrypt_policy *fscrypt_policy_to_inherit(struct inode *dir); |
0109ce76 | 720 | |
3325bea5 | 721 | #endif /* _FSCRYPT_PRIVATE_H */ |