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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * fscrypt_private.h
4 *
5 * Copyright (C) 2015, Google, Inc.
6 *
7 * Originally written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar.
8 * Heavily modified since then.
9 */
10
11#ifndef _FSCRYPT_PRIVATE_H
12#define _FSCRYPT_PRIVATE_H
13
14#include <linux/fscrypt.h>
15#include <linux/siphash.h>
16#include <crypto/hash.h>
17#include <linux/blk-crypto.h>
18
19#define CONST_STRLEN(str) (sizeof(str) - 1)
20
21#define FSCRYPT_FILE_NONCE_SIZE 16
22
23#define FSCRYPT_MIN_KEY_SIZE 16
24
25#define FSCRYPT_CONTEXT_V1 1
26#define FSCRYPT_CONTEXT_V2 2
27
28struct fscrypt_context_v1 {
29 u8 version; /* FSCRYPT_CONTEXT_V1 */
30 u8 contents_encryption_mode;
31 u8 filenames_encryption_mode;
32 u8 flags;
33 u8 master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
34 u8 nonce[FSCRYPT_FILE_NONCE_SIZE];
35};
36
37struct fscrypt_context_v2 {
38 u8 version; /* FSCRYPT_CONTEXT_V2 */
39 u8 contents_encryption_mode;
40 u8 filenames_encryption_mode;
41 u8 flags;
42 u8 __reserved[4];
43 u8 master_key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE];
44 u8 nonce[FSCRYPT_FILE_NONCE_SIZE];
45};
46
47/*
48 * fscrypt_context - the encryption context of an inode
49 *
50 * This is the on-disk equivalent of an fscrypt_policy, stored alongside each
51 * encrypted file usually in a hidden extended attribute. It contains the
52 * fields from the fscrypt_policy, in order to identify the encryption algorithm
53 * and key with which the file is encrypted. It also contains a nonce that was
54 * randomly generated by fscrypt itself; this is used as KDF input or as a tweak
55 * to cause different files to be encrypted differently.
56 */
57union fscrypt_context {
58 u8 version;
59 struct fscrypt_context_v1 v1;
60 struct fscrypt_context_v2 v2;
61};
62
63/*
64 * Return the size expected for the given fscrypt_context based on its version
65 * number, or 0 if the context version is unrecognized.
66 */
67static inline int fscrypt_context_size(const union fscrypt_context *ctx)
68{
69 switch (ctx->version) {
70 case FSCRYPT_CONTEXT_V1:
71 BUILD_BUG_ON(sizeof(ctx->v1) != 28);
72 return sizeof(ctx->v1);
73 case FSCRYPT_CONTEXT_V2:
74 BUILD_BUG_ON(sizeof(ctx->v2) != 40);
75 return sizeof(ctx->v2);
76 }
77 return 0;
78}
79
80/* Check whether an fscrypt_context has a recognized version number and size */
81static inline bool fscrypt_context_is_valid(const union fscrypt_context *ctx,
82 int ctx_size)
83{
84 return ctx_size >= 1 && ctx_size == fscrypt_context_size(ctx);
85}
86
87/* Retrieve the context's nonce, assuming the context was already validated */
88static inline const u8 *fscrypt_context_nonce(const union fscrypt_context *ctx)
89{
90 switch (ctx->version) {
91 case FSCRYPT_CONTEXT_V1:
92 return ctx->v1.nonce;
93 case FSCRYPT_CONTEXT_V2:
94 return ctx->v2.nonce;
95 }
96 WARN_ON(1);
97 return NULL;
98}
99
100#undef fscrypt_policy
101union fscrypt_policy {
102 u8 version;
103 struct fscrypt_policy_v1 v1;
104 struct fscrypt_policy_v2 v2;
105};
106
107/*
108 * Return the size expected for the given fscrypt_policy based on its version
109 * number, or 0 if the policy version is unrecognized.
110 */
111static inline int fscrypt_policy_size(const union fscrypt_policy *policy)
112{
113 switch (policy->version) {
114 case FSCRYPT_POLICY_V1:
115 return sizeof(policy->v1);
116 case FSCRYPT_POLICY_V2:
117 return sizeof(policy->v2);
118 }
119 return 0;
120}
121
122/* Return the contents encryption mode of a valid encryption policy */
123static inline u8
124fscrypt_policy_contents_mode(const union fscrypt_policy *policy)
125{
126 switch (policy->version) {
127 case FSCRYPT_POLICY_V1:
128 return policy->v1.contents_encryption_mode;
129 case FSCRYPT_POLICY_V2:
130 return policy->v2.contents_encryption_mode;
131 }
132 BUG();
133}
134
135/* Return the filenames encryption mode of a valid encryption policy */
136static inline u8
137fscrypt_policy_fnames_mode(const union fscrypt_policy *policy)
138{
139 switch (policy->version) {
140 case FSCRYPT_POLICY_V1:
141 return policy->v1.filenames_encryption_mode;
142 case FSCRYPT_POLICY_V2:
143 return policy->v2.filenames_encryption_mode;
144 }
145 BUG();
146}
147
148/* Return the flags (FSCRYPT_POLICY_FLAG*) of a valid encryption policy */
149static inline u8
150fscrypt_policy_flags(const union fscrypt_policy *policy)
151{
152 switch (policy->version) {
153 case FSCRYPT_POLICY_V1:
154 return policy->v1.flags;
155 case FSCRYPT_POLICY_V2:
156 return policy->v2.flags;
157 }
158 BUG();
159}
160
161/*
162 * For encrypted symlinks, the ciphertext length is stored at the beginning
163 * of the string in little-endian format.
164 */
165struct fscrypt_symlink_data {
166 __le16 len;
167 char encrypted_path[1];
168} __packed;
169
170/**
171 * struct fscrypt_prepared_key - a key prepared for actual encryption/decryption
172 * @tfm: crypto API transform object
173 * @blk_key: key for blk-crypto
174 *
175 * Normally only one of the fields will be non-NULL.
176 */
177struct fscrypt_prepared_key {
178 struct crypto_skcipher *tfm;
179#ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT
180 struct fscrypt_blk_crypto_key *blk_key;
181#endif
182};
183
184/*
185 * fscrypt_info - the "encryption key" for an inode
186 *
187 * When an encrypted file's key is made available, an instance of this struct is
188 * allocated and stored in ->i_crypt_info. Once created, it remains until the
189 * inode is evicted.
190 */
191struct fscrypt_info {
192
193 /* The key in a form prepared for actual encryption/decryption */
194 struct fscrypt_prepared_key ci_enc_key;
195
196 /* True if ci_enc_key should be freed when this fscrypt_info is freed */
197 bool ci_owns_key;
198
199#ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT
200 /*
201 * True if this inode will use inline encryption (blk-crypto) instead of
202 * the traditional filesystem-layer encryption.
203 */
204 bool ci_inlinecrypt;
205#endif
206
207 /*
208 * Encryption mode used for this inode. It corresponds to either the
209 * contents or filenames encryption mode, depending on the inode type.
210 */
211 struct fscrypt_mode *ci_mode;
212
213 /* Back-pointer to the inode */
214 struct inode *ci_inode;
215
216 /*
217 * The master key with which this inode was unlocked (decrypted). This
218 * will be NULL if the master key was found in a process-subscribed
219 * keyring rather than in the filesystem-level keyring.
220 */
221 struct key *ci_master_key;
222
223 /*
224 * Link in list of inodes that were unlocked with the master key.
225 * Only used when ->ci_master_key is set.
226 */
227 struct list_head ci_master_key_link;
228
229 /*
230 * If non-NULL, then encryption is done using the master key directly
231 * and ci_enc_key will equal ci_direct_key->dk_key.
232 */
233 struct fscrypt_direct_key *ci_direct_key;
234
235 /*
236 * This inode's hash key for filenames. This is a 128-bit SipHash-2-4
237 * key. This is only set for directories that use a keyed dirhash over
238 * the plaintext filenames -- currently just casefolded directories.
239 */
240 siphash_key_t ci_dirhash_key;
241 bool ci_dirhash_key_initialized;
242
243 /* The encryption policy used by this inode */
244 union fscrypt_policy ci_policy;
245
246 /* This inode's nonce, copied from the fscrypt_context */
247 u8 ci_nonce[FSCRYPT_FILE_NONCE_SIZE];
248
249 /* Hashed inode number. Only set for IV_INO_LBLK_32 */
250 u32 ci_hashed_ino;
251};
252
253typedef enum {
254 FS_DECRYPT = 0,
255 FS_ENCRYPT,
256} fscrypt_direction_t;
257
258/* crypto.c */
259extern struct kmem_cache *fscrypt_info_cachep;
260int fscrypt_initialize(unsigned int cop_flags);
261int fscrypt_crypt_block(const struct inode *inode, fscrypt_direction_t rw,
262 u64 lblk_num, struct page *src_page,
263 struct page *dest_page, unsigned int len,
264 unsigned int offs, gfp_t gfp_flags);
265struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags);
266
267void __printf(3, 4) __cold
268fscrypt_msg(const struct inode *inode, const char *level, const char *fmt, ...);
269
270#define fscrypt_warn(inode, fmt, ...) \
271 fscrypt_msg((inode), KERN_WARNING, fmt, ##__VA_ARGS__)
272#define fscrypt_err(inode, fmt, ...) \
273 fscrypt_msg((inode), KERN_ERR, fmt, ##__VA_ARGS__)
274
275#define FSCRYPT_MAX_IV_SIZE 32
276
277union fscrypt_iv {
278 struct {
279 /* logical block number within the file */
280 __le64 lblk_num;
281
282 /* per-file nonce; only set in DIRECT_KEY mode */
283 u8 nonce[FSCRYPT_FILE_NONCE_SIZE];
284 };
285 u8 raw[FSCRYPT_MAX_IV_SIZE];
286 __le64 dun[FSCRYPT_MAX_IV_SIZE / sizeof(__le64)];
287};
288
289void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num,
290 const struct fscrypt_info *ci);
291
292/* fname.c */
293int fscrypt_fname_encrypt(const struct inode *inode, const struct qstr *iname,
294 u8 *out, unsigned int olen);
295bool fscrypt_fname_encrypted_size(const struct inode *inode, u32 orig_len,
296 u32 max_len, u32 *encrypted_len_ret);
297extern const struct dentry_operations fscrypt_d_ops;
298
299/* hkdf.c */
300
301struct fscrypt_hkdf {
302 struct crypto_shash *hmac_tfm;
303};
304
305int fscrypt_init_hkdf(struct fscrypt_hkdf *hkdf, const u8 *master_key,
306 unsigned int master_key_size);
307
308/*
309 * The list of contexts in which fscrypt uses HKDF. These values are used as
310 * the first byte of the HKDF application-specific info string to guarantee that
311 * info strings are never repeated between contexts. This ensures that all HKDF
312 * outputs are unique and cryptographically isolated, i.e. knowledge of one
313 * output doesn't reveal another.
314 */
315#define HKDF_CONTEXT_KEY_IDENTIFIER 1 /* info=<empty> */
316#define HKDF_CONTEXT_PER_FILE_ENC_KEY 2 /* info=file_nonce */
317#define HKDF_CONTEXT_DIRECT_KEY 3 /* info=mode_num */
318#define HKDF_CONTEXT_IV_INO_LBLK_64_KEY 4 /* info=mode_num||fs_uuid */
319#define HKDF_CONTEXT_DIRHASH_KEY 5 /* info=file_nonce */
320#define HKDF_CONTEXT_IV_INO_LBLK_32_KEY 6 /* info=mode_num||fs_uuid */
321#define HKDF_CONTEXT_INODE_HASH_KEY 7 /* info=<empty> */
322
323int fscrypt_hkdf_expand(const struct fscrypt_hkdf *hkdf, u8 context,
324 const u8 *info, unsigned int infolen,
325 u8 *okm, unsigned int okmlen);
326
327void fscrypt_destroy_hkdf(struct fscrypt_hkdf *hkdf);
328
329/* inline_crypt.c */
330#ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT
331int fscrypt_select_encryption_impl(struct fscrypt_info *ci);
332
333static inline bool
334fscrypt_using_inline_encryption(const struct fscrypt_info *ci)
335{
336 return ci->ci_inlinecrypt;
337}
338
339int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key,
340 const u8 *raw_key,
341 const struct fscrypt_info *ci);
342
343void fscrypt_destroy_inline_crypt_key(struct fscrypt_prepared_key *prep_key);
344
345/*
346 * Check whether the crypto transform or blk-crypto key has been allocated in
347 * @prep_key, depending on which encryption implementation the file will use.
348 */
349static inline bool
350fscrypt_is_key_prepared(struct fscrypt_prepared_key *prep_key,
351 const struct fscrypt_info *ci)
352{
353 /*
354 * The two smp_load_acquire()'s here pair with the smp_store_release()'s
355 * in fscrypt_prepare_inline_crypt_key() and fscrypt_prepare_key().
356 * I.e., in some cases (namely, if this prep_key is a per-mode
357 * encryption key) another task can publish blk_key or tfm concurrently,
358 * executing a RELEASE barrier. We need to use smp_load_acquire() here
359 * to safely ACQUIRE the memory the other task published.
360 */
361 if (fscrypt_using_inline_encryption(ci))
362 return smp_load_acquire(&prep_key->blk_key) != NULL;
363 return smp_load_acquire(&prep_key->tfm) != NULL;
364}
365
366#else /* CONFIG_FS_ENCRYPTION_INLINE_CRYPT */
367
368static inline int fscrypt_select_encryption_impl(struct fscrypt_info *ci)
369{
370 return 0;
371}
372
373static inline bool
374fscrypt_using_inline_encryption(const struct fscrypt_info *ci)
375{
376 return false;
377}
378
379static inline int
380fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key,
381 const u8 *raw_key,
382 const struct fscrypt_info *ci)
383{
384 WARN_ON(1);
385 return -EOPNOTSUPP;
386}
387
388static inline void
389fscrypt_destroy_inline_crypt_key(struct fscrypt_prepared_key *prep_key)
390{
391}
392
393static inline bool
394fscrypt_is_key_prepared(struct fscrypt_prepared_key *prep_key,
395 const struct fscrypt_info *ci)
396{
397 return smp_load_acquire(&prep_key->tfm) != NULL;
398}
399#endif /* !CONFIG_FS_ENCRYPTION_INLINE_CRYPT */
400
401/* keyring.c */
402
403/*
404 * fscrypt_master_key_secret - secret key material of an in-use master key
405 */
406struct fscrypt_master_key_secret {
407
408 /*
409 * For v2 policy keys: HKDF context keyed by this master key.
410 * For v1 policy keys: not set (hkdf.hmac_tfm == NULL).
411 */
412 struct fscrypt_hkdf hkdf;
413
414 /* Size of the raw key in bytes. Set even if ->raw isn't set. */
415 u32 size;
416
417 /* For v1 policy keys: the raw key. Wiped for v2 policy keys. */
418 u8 raw[FSCRYPT_MAX_KEY_SIZE];
419
420} __randomize_layout;
421
422/*
423 * fscrypt_master_key - an in-use master key
424 *
425 * This represents a master encryption key which has been added to the
426 * filesystem and can be used to "unlock" the encrypted files which were
427 * encrypted with it.
428 */
429struct fscrypt_master_key {
430
431 /*
432 * The secret key material. After FS_IOC_REMOVE_ENCRYPTION_KEY is
433 * executed, this is wiped and no new inodes can be unlocked with this
434 * key; however, there may still be inodes in ->mk_decrypted_inodes
435 * which could not be evicted. As long as some inodes still remain,
436 * FS_IOC_REMOVE_ENCRYPTION_KEY can be retried, or
437 * FS_IOC_ADD_ENCRYPTION_KEY can add the secret again.
438 *
439 * Locking: protected by key->sem (outer) and mk_secret_sem (inner).
440 * The reason for two locks is that key->sem also protects modifying
441 * mk_users, which ranks it above the semaphore for the keyring key
442 * type, which is in turn above page faults (via keyring_read). But
443 * sometimes filesystems call fscrypt_get_encryption_info() from within
444 * a transaction, which ranks it below page faults. So we need a
445 * separate lock which protects mk_secret but not also mk_users.
446 */
447 struct fscrypt_master_key_secret mk_secret;
448 struct rw_semaphore mk_secret_sem;
449
450 /*
451 * For v1 policy keys: an arbitrary key descriptor which was assigned by
452 * userspace (->descriptor).
453 *
454 * For v2 policy keys: a cryptographic hash of this key (->identifier).
455 */
456 struct fscrypt_key_specifier mk_spec;
457
458 /*
459 * Keyring which contains a key of type 'key_type_fscrypt_user' for each
460 * user who has added this key. Normally each key will be added by just
461 * one user, but it's possible that multiple users share a key, and in
462 * that case we need to keep track of those users so that one user can't
463 * remove the key before the others want it removed too.
464 *
465 * This is NULL for v1 policy keys; those can only be added by root.
466 *
467 * Locking: in addition to this keyrings own semaphore, this is
468 * protected by the master key's key->sem, so we can do atomic
469 * search+insert. It can also be searched without taking any locks, but
470 * in that case the returned key may have already been removed.
471 */
472 struct key *mk_users;
473
474 /*
475 * Length of ->mk_decrypted_inodes, plus one if mk_secret is present.
476 * Once this goes to 0, the master key is removed from ->s_master_keys.
477 * The 'struct fscrypt_master_key' will continue to live as long as the
478 * 'struct key' whose payload it is, but we won't let this reference
479 * count rise again.
480 */
481 refcount_t mk_refcount;
482
483 /*
484 * List of inodes that were unlocked using this key. This allows the
485 * inodes to be evicted efficiently if the key is removed.
486 */
487 struct list_head mk_decrypted_inodes;
488 spinlock_t mk_decrypted_inodes_lock;
489
490 /*
491 * Per-mode encryption keys for the various types of encryption policies
492 * that use them. Allocated and derived on-demand.
493 */
494 struct fscrypt_prepared_key mk_direct_keys[__FSCRYPT_MODE_MAX + 1];
495 struct fscrypt_prepared_key mk_iv_ino_lblk_64_keys[__FSCRYPT_MODE_MAX + 1];
496 struct fscrypt_prepared_key mk_iv_ino_lblk_32_keys[__FSCRYPT_MODE_MAX + 1];
497
498 /* Hash key for inode numbers. Initialized only when needed. */
499 siphash_key_t mk_ino_hash_key;
500 bool mk_ino_hash_key_initialized;
501
502} __randomize_layout;
503
504static inline bool
505is_master_key_secret_present(const struct fscrypt_master_key_secret *secret)
506{
507 /*
508 * The READ_ONCE() is only necessary for fscrypt_drop_inode() and
509 * fscrypt_key_describe(). These run in atomic context, so they can't
510 * take ->mk_secret_sem and thus 'secret' can change concurrently which
511 * would be a data race. But they only need to know whether the secret
512 * *was* present at the time of check, so READ_ONCE() suffices.
513 */
514 return READ_ONCE(secret->size) != 0;
515}
516
517static inline const char *master_key_spec_type(
518 const struct fscrypt_key_specifier *spec)
519{
520 switch (spec->type) {
521 case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
522 return "descriptor";
523 case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER:
524 return "identifier";
525 }
526 return "[unknown]";
527}
528
529static inline int master_key_spec_len(const struct fscrypt_key_specifier *spec)
530{
531 switch (spec->type) {
532 case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
533 return FSCRYPT_KEY_DESCRIPTOR_SIZE;
534 case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER:
535 return FSCRYPT_KEY_IDENTIFIER_SIZE;
536 }
537 return 0;
538}
539
540struct key *
541fscrypt_find_master_key(struct super_block *sb,
542 const struct fscrypt_key_specifier *mk_spec);
543
544int fscrypt_add_test_dummy_key(struct super_block *sb,
545 struct fscrypt_key_specifier *key_spec);
546
547int fscrypt_verify_key_added(struct super_block *sb,
548 const u8 identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]);
549
550int __init fscrypt_init_keyring(void);
551
552/* keysetup.c */
553
554struct fscrypt_mode {
555 const char *friendly_name;
556 const char *cipher_str;
557 int keysize;
558 int ivsize;
559 int logged_impl_name;
560 enum blk_crypto_mode_num blk_crypto_mode;
561};
562
563extern struct fscrypt_mode fscrypt_modes[];
564
565int fscrypt_prepare_key(struct fscrypt_prepared_key *prep_key,
566 const u8 *raw_key, const struct fscrypt_info *ci);
567
568void fscrypt_destroy_prepared_key(struct fscrypt_prepared_key *prep_key);
569
570int fscrypt_set_per_file_enc_key(struct fscrypt_info *ci, const u8 *raw_key);
571
572int fscrypt_derive_dirhash_key(struct fscrypt_info *ci,
573 const struct fscrypt_master_key *mk);
574
575/* keysetup_v1.c */
576
577void fscrypt_put_direct_key(struct fscrypt_direct_key *dk);
578
579int fscrypt_setup_v1_file_key(struct fscrypt_info *ci,
580 const u8 *raw_master_key);
581
582int fscrypt_setup_v1_file_key_via_subscribed_keyrings(struct fscrypt_info *ci);
583
584/* policy.c */
585
586bool fscrypt_policies_equal(const union fscrypt_policy *policy1,
587 const union fscrypt_policy *policy2);
588bool fscrypt_supported_policy(const union fscrypt_policy *policy_u,
589 const struct inode *inode);
590int fscrypt_policy_from_context(union fscrypt_policy *policy_u,
591 const union fscrypt_context *ctx_u,
592 int ctx_size);
593
594#endif /* _FSCRYPT_PRIVATE_H */
1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * fscrypt_private.h
4 *
5 * Copyright (C) 2015, Google, Inc.
6 *
7 * Originally written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar.
8 * Heavily modified since then.
9 */
10
11#ifndef _FSCRYPT_PRIVATE_H
12#define _FSCRYPT_PRIVATE_H
13
14#include <linux/fscrypt.h>
15#include <linux/siphash.h>
16#include <crypto/hash.h>
17#include <linux/blk-crypto.h>
18
19#define CONST_STRLEN(str) (sizeof(str) - 1)
20
21#define FSCRYPT_FILE_NONCE_SIZE 16
22
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 */
28#define FSCRYPT_MIN_KEY_SIZE 16
29
30#define FSCRYPT_CONTEXT_V1 1
31#define FSCRYPT_CONTEXT_V2 2
32
33/* Keep this in sync with include/uapi/linux/fscrypt.h */
34#define FSCRYPT_MODE_MAX FSCRYPT_MODE_AES_256_HCTR2
35
36struct fscrypt_context_v1 {
37 u8 version; /* FSCRYPT_CONTEXT_V1 */
38 u8 contents_encryption_mode;
39 u8 filenames_encryption_mode;
40 u8 flags;
41 u8 master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
42 u8 nonce[FSCRYPT_FILE_NONCE_SIZE];
43};
44
45struct fscrypt_context_v2 {
46 u8 version; /* FSCRYPT_CONTEXT_V2 */
47 u8 contents_encryption_mode;
48 u8 filenames_encryption_mode;
49 u8 flags;
50 u8 log2_data_unit_size;
51 u8 __reserved[3];
52 u8 master_key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE];
53 u8 nonce[FSCRYPT_FILE_NONCE_SIZE];
54};
55
56/*
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 */
66union 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 */
76static 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
89/* Check whether an fscrypt_context has a recognized version number and size */
90static 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 */
97static 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 }
105 WARN_ON_ONCE(1);
106 return NULL;
107}
108
109union 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 */
119static 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 */
131static inline u8
132fscrypt_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 */
144static inline u8
145fscrypt_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 */
157static inline u8
158fscrypt_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
169static inline int
170fscrypt_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
176static inline int
177fscrypt_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
189/*
190 * For encrypted symlinks, the ciphertext length is stored at the beginning
191 * of the string in little-endian format.
192 */
193struct fscrypt_symlink_data {
194 __le16 len;
195 char encrypted_path[];
196} __packed;
197
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 */
205struct fscrypt_prepared_key {
206 struct crypto_skcipher *tfm;
207#ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT
208 struct blk_crypto_key *blk_key;
209#endif
210};
211
212/*
213 * fscrypt_inode_info - the "encryption key" for an inode
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.
218 */
219struct fscrypt_inode_info {
220
221 /* The key in a form prepared for actual encryption/decryption */
222 struct fscrypt_prepared_key ci_enc_key;
223
224 /* True if ci_enc_key should be freed when this struct is freed */
225 bool ci_owns_key;
226
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 */
232 bool ci_inlinecrypt;
233#endif
234
235 /*
236 * log2 of the data unit size (granularity of contents encryption) of
237 * this file. This is computable from ci_policy and ci_inode but is
238 * cached here for efficiency. Only used for regular files.
239 */
240 u8 ci_data_unit_bits;
241
242 /* Cached value: log2 of number of data units per FS block */
243 u8 ci_data_units_per_block_bits;
244
245 /*
246 * Encryption mode used for this inode. It corresponds to either the
247 * contents or filenames encryption mode, depending on the inode type.
248 */
249 struct fscrypt_mode *ci_mode;
250
251 /* Back-pointer to the inode */
252 struct inode *ci_inode;
253
254 /*
255 * The master key with which this inode was unlocked (decrypted). This
256 * will be NULL if the master key was found in a process-subscribed
257 * keyring rather than in the filesystem-level keyring.
258 */
259 struct fscrypt_master_key *ci_master_key;
260
261 /*
262 * Link in list of inodes that were unlocked with the master key.
263 * Only used when ->ci_master_key is set.
264 */
265 struct list_head ci_master_key_link;
266
267 /*
268 * If non-NULL, then encryption is done using the master key directly
269 * and ci_enc_key will equal ci_direct_key->dk_key.
270 */
271 struct fscrypt_direct_key *ci_direct_key;
272
273 /*
274 * This inode's hash key for filenames. This is a 128-bit SipHash-2-4
275 * key. This is only set for directories that use a keyed dirhash over
276 * the plaintext filenames -- currently just casefolded directories.
277 */
278 siphash_key_t ci_dirhash_key;
279 bool ci_dirhash_key_initialized;
280
281 /* The encryption policy used by this inode */
282 union fscrypt_policy ci_policy;
283
284 /* This inode's nonce, copied from the fscrypt_context */
285 u8 ci_nonce[FSCRYPT_FILE_NONCE_SIZE];
286
287 /* Hashed inode number. Only set for IV_INO_LBLK_32 */
288 u32 ci_hashed_ino;
289};
290
291typedef enum {
292 FS_DECRYPT = 0,
293 FS_ENCRYPT,
294} fscrypt_direction_t;
295
296/* crypto.c */
297extern struct kmem_cache *fscrypt_inode_info_cachep;
298int fscrypt_initialize(struct super_block *sb);
299int fscrypt_crypt_data_unit(const struct fscrypt_inode_info *ci,
300 fscrypt_direction_t rw, u64 index,
301 struct page *src_page, struct page *dest_page,
302 unsigned int len, unsigned int offs,
303 gfp_t gfp_flags);
304struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags);
305
306void __printf(3, 4) __cold
307fscrypt_msg(const struct inode *inode, const char *level, const char *fmt, ...);
308
309#define fscrypt_warn(inode, fmt, ...) \
310 fscrypt_msg((inode), KERN_WARNING, fmt, ##__VA_ARGS__)
311#define fscrypt_err(inode, fmt, ...) \
312 fscrypt_msg((inode), KERN_ERR, fmt, ##__VA_ARGS__)
313
314#define FSCRYPT_MAX_IV_SIZE 32
315
316union fscrypt_iv {
317 struct {
318 /* zero-based index of data unit within the file */
319 __le64 index;
320
321 /* per-file nonce; only set in DIRECT_KEY mode */
322 u8 nonce[FSCRYPT_FILE_NONCE_SIZE];
323 };
324 u8 raw[FSCRYPT_MAX_IV_SIZE];
325 __le64 dun[FSCRYPT_MAX_IV_SIZE / sizeof(__le64)];
326};
327
328void fscrypt_generate_iv(union fscrypt_iv *iv, u64 index,
329 const struct fscrypt_inode_info *ci);
330
331/*
332 * Return the number of bits used by the maximum file data unit index that is
333 * possible on the given filesystem, using the given log2 data unit size.
334 */
335static inline int
336fscrypt_max_file_dun_bits(const struct super_block *sb, int du_bits)
337{
338 return fls64(sb->s_maxbytes - 1) - du_bits;
339}
340
341/* fname.c */
342bool __fscrypt_fname_encrypted_size(const union fscrypt_policy *policy,
343 u32 orig_len, u32 max_len,
344 u32 *encrypted_len_ret);
345
346/* hkdf.c */
347struct fscrypt_hkdf {
348 struct crypto_shash *hmac_tfm;
349};
350
351int fscrypt_init_hkdf(struct fscrypt_hkdf *hkdf, const u8 *master_key,
352 unsigned int master_key_size);
353
354/*
355 * The list of contexts in which fscrypt uses HKDF. These values are used as
356 * the first byte of the HKDF application-specific info string to guarantee that
357 * info strings are never repeated between contexts. This ensures that all HKDF
358 * outputs are unique and cryptographically isolated, i.e. knowledge of one
359 * output doesn't reveal another.
360 */
361#define HKDF_CONTEXT_KEY_IDENTIFIER 1 /* info=<empty> */
362#define HKDF_CONTEXT_PER_FILE_ENC_KEY 2 /* info=file_nonce */
363#define HKDF_CONTEXT_DIRECT_KEY 3 /* info=mode_num */
364#define HKDF_CONTEXT_IV_INO_LBLK_64_KEY 4 /* info=mode_num||fs_uuid */
365#define HKDF_CONTEXT_DIRHASH_KEY 5 /* info=file_nonce */
366#define HKDF_CONTEXT_IV_INO_LBLK_32_KEY 6 /* info=mode_num||fs_uuid */
367#define HKDF_CONTEXT_INODE_HASH_KEY 7 /* info=<empty> */
368
369int fscrypt_hkdf_expand(const struct fscrypt_hkdf *hkdf, u8 context,
370 const u8 *info, unsigned int infolen,
371 u8 *okm, unsigned int okmlen);
372
373void fscrypt_destroy_hkdf(struct fscrypt_hkdf *hkdf);
374
375/* inline_crypt.c */
376#ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT
377int fscrypt_select_encryption_impl(struct fscrypt_inode_info *ci);
378
379static inline bool
380fscrypt_using_inline_encryption(const struct fscrypt_inode_info *ci)
381{
382 return ci->ci_inlinecrypt;
383}
384
385int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key,
386 const u8 *raw_key,
387 const struct fscrypt_inode_info *ci);
388
389void fscrypt_destroy_inline_crypt_key(struct super_block *sb,
390 struct fscrypt_prepared_key *prep_key);
391
392/*
393 * Check whether the crypto transform or blk-crypto key has been allocated in
394 * @prep_key, depending on which encryption implementation the file will use.
395 */
396static inline bool
397fscrypt_is_key_prepared(struct fscrypt_prepared_key *prep_key,
398 const struct fscrypt_inode_info *ci)
399{
400 /*
401 * The two smp_load_acquire()'s here pair with the smp_store_release()'s
402 * in fscrypt_prepare_inline_crypt_key() and fscrypt_prepare_key().
403 * I.e., in some cases (namely, if this prep_key is a per-mode
404 * encryption key) another task can publish blk_key or tfm concurrently,
405 * executing a RELEASE barrier. We need to use smp_load_acquire() here
406 * to safely ACQUIRE the memory the other task published.
407 */
408 if (fscrypt_using_inline_encryption(ci))
409 return smp_load_acquire(&prep_key->blk_key) != NULL;
410 return smp_load_acquire(&prep_key->tfm) != NULL;
411}
412
413#else /* CONFIG_FS_ENCRYPTION_INLINE_CRYPT */
414
415static inline int fscrypt_select_encryption_impl(struct fscrypt_inode_info *ci)
416{
417 return 0;
418}
419
420static inline bool
421fscrypt_using_inline_encryption(const struct fscrypt_inode_info *ci)
422{
423 return false;
424}
425
426static inline int
427fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key,
428 const u8 *raw_key,
429 const struct fscrypt_inode_info *ci)
430{
431 WARN_ON_ONCE(1);
432 return -EOPNOTSUPP;
433}
434
435static inline void
436fscrypt_destroy_inline_crypt_key(struct super_block *sb,
437 struct fscrypt_prepared_key *prep_key)
438{
439}
440
441static inline bool
442fscrypt_is_key_prepared(struct fscrypt_prepared_key *prep_key,
443 const struct fscrypt_inode_info *ci)
444{
445 return smp_load_acquire(&prep_key->tfm) != NULL;
446}
447#endif /* !CONFIG_FS_ENCRYPTION_INLINE_CRYPT */
448
449/* keyring.c */
450
451/*
452 * fscrypt_master_key_secret - secret key material of an in-use master key
453 */
454struct fscrypt_master_key_secret {
455
456 /*
457 * For v2 policy keys: HKDF context keyed by this master key.
458 * For v1 policy keys: not set (hkdf.hmac_tfm == NULL).
459 */
460 struct fscrypt_hkdf hkdf;
461
462 /*
463 * Size of the raw key in bytes. This remains set even if ->raw was
464 * zeroized due to no longer being needed. I.e. we still remember the
465 * size of the key even if we don't need to remember the key itself.
466 */
467 u32 size;
468
469 /* For v1 policy keys: the raw key. Wiped for v2 policy keys. */
470 u8 raw[FSCRYPT_MAX_KEY_SIZE];
471
472} __randomize_layout;
473
474/*
475 * fscrypt_master_key - an in-use master key
476 *
477 * This represents a master encryption key which has been added to the
478 * filesystem. There are three high-level states that a key can be in:
479 *
480 * FSCRYPT_KEY_STATUS_PRESENT
481 * Key is fully usable; it can be used to unlock inodes that are encrypted
482 * with it (this includes being able to create new inodes). ->mk_present
483 * indicates whether the key is in this state. ->mk_secret exists, the key
484 * is in the keyring, and ->mk_active_refs > 0 due to ->mk_present.
485 *
486 * FSCRYPT_KEY_STATUS_INCOMPLETELY_REMOVED
487 * Removal of this key has been initiated, but some inodes that were
488 * unlocked with it are still in-use. Like ABSENT, ->mk_secret is wiped,
489 * and the key can no longer be used to unlock inodes. Unlike ABSENT, the
490 * key is still in the keyring; ->mk_decrypted_inodes is nonempty; and
491 * ->mk_active_refs > 0, being equal to the size of ->mk_decrypted_inodes.
492 *
493 * This state transitions to ABSENT if ->mk_decrypted_inodes becomes empty,
494 * or to PRESENT if FS_IOC_ADD_ENCRYPTION_KEY is called again for this key.
495 *
496 * FSCRYPT_KEY_STATUS_ABSENT
497 * Key is fully removed. The key is no longer in the keyring,
498 * ->mk_decrypted_inodes is empty, ->mk_active_refs == 0, ->mk_secret is
499 * wiped, and the key can no longer be used to unlock inodes.
500 */
501struct fscrypt_master_key {
502
503 /*
504 * Link in ->s_master_keys->key_hashtable.
505 * Only valid if ->mk_active_refs > 0.
506 */
507 struct hlist_node mk_node;
508
509 /* Semaphore that protects ->mk_secret, ->mk_users, and ->mk_present */
510 struct rw_semaphore mk_sem;
511
512 /*
513 * Active and structural reference counts. An active ref guarantees
514 * that the struct continues to exist, continues to be in the keyring
515 * ->s_master_keys, and that any embedded subkeys (e.g.
516 * ->mk_direct_keys) that have been prepared continue to exist.
517 * A structural ref only guarantees that the struct continues to exist.
518 *
519 * There is one active ref associated with ->mk_present being true, and
520 * one active ref for each inode in ->mk_decrypted_inodes.
521 *
522 * There is one structural ref associated with the active refcount being
523 * nonzero. Finding a key in the keyring also takes a structural ref,
524 * which is then held temporarily while the key is operated on.
525 */
526 refcount_t mk_active_refs;
527 refcount_t mk_struct_refs;
528
529 struct rcu_head mk_rcu_head;
530
531 /*
532 * The secret key material. Wiped as soon as it is no longer needed;
533 * for details, see the fscrypt_master_key struct comment.
534 *
535 * Locking: protected by ->mk_sem.
536 */
537 struct fscrypt_master_key_secret mk_secret;
538
539 /*
540 * For v1 policy keys: an arbitrary key descriptor which was assigned by
541 * userspace (->descriptor).
542 *
543 * For v2 policy keys: a cryptographic hash of this key (->identifier).
544 */
545 struct fscrypt_key_specifier mk_spec;
546
547 /*
548 * Keyring which contains a key of type 'key_type_fscrypt_user' for each
549 * user who has added this key. Normally each key will be added by just
550 * one user, but it's possible that multiple users share a key, and in
551 * that case we need to keep track of those users so that one user can't
552 * remove the key before the others want it removed too.
553 *
554 * This is NULL for v1 policy keys; those can only be added by root.
555 *
556 * Locking: protected by ->mk_sem. (We don't just rely on the keyrings
557 * subsystem semaphore ->mk_users->sem, as we need support for atomic
558 * search+insert along with proper synchronization with other fields.)
559 */
560 struct key *mk_users;
561
562 /*
563 * List of inodes that were unlocked using this key. This allows the
564 * inodes to be evicted efficiently if the key is removed.
565 */
566 struct list_head mk_decrypted_inodes;
567 spinlock_t mk_decrypted_inodes_lock;
568
569 /*
570 * Per-mode encryption keys for the various types of encryption policies
571 * that use them. Allocated and derived on-demand.
572 */
573 struct fscrypt_prepared_key mk_direct_keys[FSCRYPT_MODE_MAX + 1];
574 struct fscrypt_prepared_key mk_iv_ino_lblk_64_keys[FSCRYPT_MODE_MAX + 1];
575 struct fscrypt_prepared_key mk_iv_ino_lblk_32_keys[FSCRYPT_MODE_MAX + 1];
576
577 /* Hash key for inode numbers. Initialized only when needed. */
578 siphash_key_t mk_ino_hash_key;
579 bool mk_ino_hash_key_initialized;
580
581 /*
582 * Whether this key is in the "present" state, i.e. fully usable. For
583 * details, see the fscrypt_master_key struct comment.
584 *
585 * Locking: protected by ->mk_sem, but can be read locklessly using
586 * READ_ONCE(). Writers must use WRITE_ONCE() when concurrent readers
587 * are possible.
588 */
589 bool mk_present;
590
591} __randomize_layout;
592
593static inline const char *master_key_spec_type(
594 const struct fscrypt_key_specifier *spec)
595{
596 switch (spec->type) {
597 case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
598 return "descriptor";
599 case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER:
600 return "identifier";
601 }
602 return "[unknown]";
603}
604
605static inline int master_key_spec_len(const struct fscrypt_key_specifier *spec)
606{
607 switch (spec->type) {
608 case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
609 return FSCRYPT_KEY_DESCRIPTOR_SIZE;
610 case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER:
611 return FSCRYPT_KEY_IDENTIFIER_SIZE;
612 }
613 return 0;
614}
615
616void fscrypt_put_master_key(struct fscrypt_master_key *mk);
617
618void fscrypt_put_master_key_activeref(struct super_block *sb,
619 struct fscrypt_master_key *mk);
620
621struct fscrypt_master_key *
622fscrypt_find_master_key(struct super_block *sb,
623 const struct fscrypt_key_specifier *mk_spec);
624
625int fscrypt_get_test_dummy_key_identifier(
626 u8 key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]);
627
628int fscrypt_add_test_dummy_key(struct super_block *sb,
629 struct fscrypt_key_specifier *key_spec);
630
631int fscrypt_verify_key_added(struct super_block *sb,
632 const u8 identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]);
633
634int __init fscrypt_init_keyring(void);
635
636/* keysetup.c */
637
638struct fscrypt_mode {
639 const char *friendly_name;
640 const char *cipher_str;
641 int keysize; /* key size in bytes */
642 int security_strength; /* security strength in bytes */
643 int ivsize; /* IV size in bytes */
644 int logged_cryptoapi_impl;
645 int logged_blk_crypto_native;
646 int logged_blk_crypto_fallback;
647 enum blk_crypto_mode_num blk_crypto_mode;
648};
649
650extern struct fscrypt_mode fscrypt_modes[];
651
652int fscrypt_prepare_key(struct fscrypt_prepared_key *prep_key,
653 const u8 *raw_key, const struct fscrypt_inode_info *ci);
654
655void fscrypt_destroy_prepared_key(struct super_block *sb,
656 struct fscrypt_prepared_key *prep_key);
657
658int fscrypt_set_per_file_enc_key(struct fscrypt_inode_info *ci,
659 const u8 *raw_key);
660
661int fscrypt_derive_dirhash_key(struct fscrypt_inode_info *ci,
662 const struct fscrypt_master_key *mk);
663
664void fscrypt_hash_inode_number(struct fscrypt_inode_info *ci,
665 const struct fscrypt_master_key *mk);
666
667int fscrypt_get_encryption_info(struct inode *inode, bool allow_unsupported);
668
669/**
670 * fscrypt_require_key() - require an inode's encryption key
671 * @inode: the inode we need the key for
672 *
673 * If the inode is encrypted, set up its encryption key if not already done.
674 * Then require that the key be present and return -ENOKEY otherwise.
675 *
676 * No locks are needed, and the key will live as long as the struct inode --- so
677 * it won't go away from under you.
678 *
679 * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code
680 * if a problem occurred while setting up the encryption key.
681 */
682static inline int fscrypt_require_key(struct inode *inode)
683{
684 if (IS_ENCRYPTED(inode)) {
685 int err = fscrypt_get_encryption_info(inode, false);
686
687 if (err)
688 return err;
689 if (!fscrypt_has_encryption_key(inode))
690 return -ENOKEY;
691 }
692 return 0;
693}
694
695/* keysetup_v1.c */
696
697void fscrypt_put_direct_key(struct fscrypt_direct_key *dk);
698
699int fscrypt_setup_v1_file_key(struct fscrypt_inode_info *ci,
700 const u8 *raw_master_key);
701
702int fscrypt_setup_v1_file_key_via_subscribed_keyrings(
703 struct fscrypt_inode_info *ci);
704
705/* policy.c */
706
707bool fscrypt_policies_equal(const union fscrypt_policy *policy1,
708 const union fscrypt_policy *policy2);
709int fscrypt_policy_to_key_spec(const union fscrypt_policy *policy,
710 struct fscrypt_key_specifier *key_spec);
711const union fscrypt_policy *fscrypt_get_dummy_policy(struct super_block *sb);
712bool fscrypt_supported_policy(const union fscrypt_policy *policy_u,
713 const struct inode *inode);
714int fscrypt_policy_from_context(union fscrypt_policy *policy_u,
715 const union fscrypt_context *ctx_u,
716 int ctx_size);
717const union fscrypt_policy *fscrypt_policy_to_inherit(struct inode *dir);
718
719#endif /* _FSCRYPT_PRIVATE_H */