xref: /openbmc/linux/fs/crypto/fscrypt_private.h (revision d617ef03)
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 
36 struct 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 
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];
52 	u8 nonce[FSCRYPT_FILE_NONCE_SIZE];
53 };
54 
55 /*
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  */
fscrypt_context_size(const union fscrypt_context * ctx)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 
88 /* Check whether an fscrypt_context has a recognized version number and size */
fscrypt_context_is_valid(const union fscrypt_context * ctx,int ctx_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 */
fscrypt_context_nonce(const union fscrypt_context * ctx)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 	}
104 	WARN_ON_ONCE(1);
105 	return NULL;
106 }
107 
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  */
fscrypt_policy_size(const union fscrypt_policy * policy)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
fscrypt_policy_contents_mode(const union fscrypt_policy * policy)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
fscrypt_policy_fnames_mode(const union fscrypt_policy * policy)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
fscrypt_policy_flags(const union fscrypt_policy * policy)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 
168 /*
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[];
175 } __packed;
176 
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
187 	struct blk_crypto_key *blk_key;
188 #endif
189 };
190 
191 /*
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.
197  */
198 struct fscrypt_info {
199 
200 	/* The key in a form prepared for actual encryption/decryption */
201 	struct fscrypt_prepared_key ci_enc_key;
202 
203 	/* True if ci_enc_key should be freed when this fscrypt_info is freed */
204 	bool ci_owns_key;
205 
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 
214 	/*
215 	 * Encryption mode used for this inode.  It corresponds to either the
216 	 * contents or filenames encryption mode, depending on the inode type.
217 	 */
218 	struct fscrypt_mode *ci_mode;
219 
220 	/* Back-pointer to the inode */
221 	struct inode *ci_inode;
222 
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 	 */
228 	struct fscrypt_master_key *ci_master_key;
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 
236 	/*
237 	 * If non-NULL, then encryption is done using the master key directly
238 	 * and ci_enc_key will equal ci_direct_key->dk_key.
239 	 */
240 	struct fscrypt_direct_key *ci_direct_key;
241 
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 
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 */
254 	u8 ci_nonce[FSCRYPT_FILE_NONCE_SIZE];
255 
256 	/* Hashed inode number.  Only set for IV_INO_LBLK_32 */
257 	u32 ci_hashed_ino;
258 };
259 
260 typedef enum {
261 	FS_DECRYPT = 0,
262 	FS_ENCRYPT,
263 } fscrypt_direction_t;
264 
265 /* crypto.c */
266 extern struct kmem_cache *fscrypt_info_cachep;
267 int fscrypt_initialize(struct super_block *sb);
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
275 fscrypt_msg(const struct inode *inode, const char *level, const char *fmt, ...);
276 
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__)
281 
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 */
290 		u8 nonce[FSCRYPT_FILE_NONCE_SIZE];
291 	};
292 	u8 raw[FSCRYPT_MAX_IV_SIZE];
293 	__le64 dun[FSCRYPT_MAX_IV_SIZE / sizeof(__le64)];
294 };
295 
296 void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num,
297 			 const struct fscrypt_info *ci);
298 
299 /* fname.c */
300 bool __fscrypt_fname_encrypted_size(const union fscrypt_policy *policy,
301 				    u32 orig_len, u32 max_len,
302 				    u32 *encrypted_len_ret);
303 
304 /* hkdf.c */
305 struct fscrypt_hkdf {
306 	struct crypto_shash *hmac_tfm;
307 };
308 
309 int fscrypt_init_hkdf(struct fscrypt_hkdf *hkdf, const u8 *master_key,
310 		      unsigned int master_key_size);
311 
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  */
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>		*/
326 
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);
330 
331 void fscrypt_destroy_hkdf(struct fscrypt_hkdf *hkdf);
332 
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
fscrypt_using_inline_encryption(const struct fscrypt_info * ci)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 
347 void fscrypt_destroy_inline_crypt_key(struct super_block *sb,
348 				      struct fscrypt_prepared_key *prep_key);
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
fscrypt_is_key_prepared(struct fscrypt_prepared_key * prep_key,const struct fscrypt_info * ci)355 fscrypt_is_key_prepared(struct fscrypt_prepared_key *prep_key,
356 			const struct fscrypt_info *ci)
357 {
358 	/*
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.
365 	 */
366 	if (fscrypt_using_inline_encryption(ci))
367 		return smp_load_acquire(&prep_key->blk_key) != NULL;
368 	return smp_load_acquire(&prep_key->tfm) != NULL;
369 }
370 
371 #else /* CONFIG_FS_ENCRYPTION_INLINE_CRYPT */
372 
fscrypt_select_encryption_impl(struct fscrypt_info * ci)373 static inline int fscrypt_select_encryption_impl(struct fscrypt_info *ci)
374 {
375 	return 0;
376 }
377 
378 static inline bool
fscrypt_using_inline_encryption(const struct fscrypt_info * ci)379 fscrypt_using_inline_encryption(const struct fscrypt_info *ci)
380 {
381 	return false;
382 }
383 
384 static inline int
fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key * prep_key,const u8 * raw_key,const struct fscrypt_info * ci)385 fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key,
386 				 const u8 *raw_key,
387 				 const struct fscrypt_info *ci)
388 {
389 	WARN_ON_ONCE(1);
390 	return -EOPNOTSUPP;
391 }
392 
393 static inline void
fscrypt_destroy_inline_crypt_key(struct super_block * sb,struct fscrypt_prepared_key * prep_key)394 fscrypt_destroy_inline_crypt_key(struct super_block *sb,
395 				 struct fscrypt_prepared_key *prep_key)
396 {
397 }
398 
399 static inline bool
fscrypt_is_key_prepared(struct fscrypt_prepared_key * prep_key,const struct fscrypt_info * ci)400 fscrypt_is_key_prepared(struct fscrypt_prepared_key *prep_key,
401 			const struct fscrypt_info *ci)
402 {
403 	return smp_load_acquire(&prep_key->tfm) != NULL;
404 }
405 #endif /* !CONFIG_FS_ENCRYPTION_INLINE_CRYPT */
406 
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 
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 
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 	 */
425 	u32			size;
426 
427 	/* For v1 policy keys: the raw key.  Wiped for v2 policy keys. */
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 
441 	/*
442 	 * Link in ->s_master_keys->key_hashtable.
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
453 	 * ->s_master_keys, and that any embedded subkeys (e.g.
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 
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 	 *
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.
481 	 */
482 	struct fscrypt_master_key_secret	mk_secret;
483 
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 	 */
490 	struct fscrypt_key_specifier		mk_spec;
491 
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 	 *
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.)
504 	 */
505 	struct key		*mk_users;
506 
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 
514 	/*
515 	 * Per-mode encryption keys for the various types of encryption policies
516 	 * that use them.  Allocated and derived on-demand.
517 	 */
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];
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;
525 
526 } __randomize_layout;
527 
528 static inline bool
is_master_key_secret_present(const struct fscrypt_master_key_secret * secret)529 is_master_key_secret_present(const struct fscrypt_master_key_secret *secret)
530 {
531 	/*
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
536 	 * secret *was* present at the time of check, so READ_ONCE() suffices.
537 	 */
538 	return READ_ONCE(secret->size) != 0;
539 }
540 
master_key_spec_type(const struct fscrypt_key_specifier * spec)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";
547 	case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER:
548 		return "identifier";
549 	}
550 	return "[unknown]";
551 }
552 
master_key_spec_len(const struct fscrypt_key_specifier * spec)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;
558 	case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER:
559 		return FSCRYPT_KEY_IDENTIFIER_SIZE;
560 	}
561 	return 0;
562 }
563 
564 void fscrypt_put_master_key(struct fscrypt_master_key *mk);
565 
566 void fscrypt_put_master_key_activeref(struct super_block *sb,
567 				      struct fscrypt_master_key *mk);
568 
569 struct fscrypt_master_key *
570 fscrypt_find_master_key(struct super_block *sb,
571 			const struct fscrypt_key_specifier *mk_spec);
572 
573 int fscrypt_get_test_dummy_key_identifier(
574 			  u8 key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]);
575 
576 int fscrypt_add_test_dummy_key(struct super_block *sb,
577 			       struct fscrypt_key_specifier *key_spec);
578 
579 int fscrypt_verify_key_added(struct super_block *sb,
580 			     const u8 identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]);
581 
582 int __init fscrypt_init_keyring(void);
583 
584 /* keysetup.c */
585 
586 struct fscrypt_mode {
587 	const char *friendly_name;
588 	const char *cipher_str;
589 	int keysize;		/* key size in bytes */
590 	int security_strength;	/* security strength in bytes */
591 	int ivsize;		/* IV size in bytes */
592 	int logged_cryptoapi_impl;
593 	int logged_blk_crypto_native;
594 	int logged_blk_crypto_fallback;
595 	enum blk_crypto_mode_num blk_crypto_mode;
596 };
597 
598 extern struct fscrypt_mode fscrypt_modes[];
599 
600 int fscrypt_prepare_key(struct fscrypt_prepared_key *prep_key,
601 			const u8 *raw_key, const struct fscrypt_info *ci);
602 
603 void fscrypt_destroy_prepared_key(struct super_block *sb,
604 				  struct fscrypt_prepared_key *prep_key);
605 
606 int fscrypt_set_per_file_enc_key(struct fscrypt_info *ci, const u8 *raw_key);
607 
608 int fscrypt_derive_dirhash_key(struct fscrypt_info *ci,
609 			       const struct fscrypt_master_key *mk);
610 
611 void fscrypt_hash_inode_number(struct fscrypt_info *ci,
612 			       const struct fscrypt_master_key *mk);
613 
614 int fscrypt_get_encryption_info(struct inode *inode, bool allow_unsupported);
615 
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  */
fscrypt_require_key(struct inode * inode)629 static inline int fscrypt_require_key(struct inode *inode)
630 {
631 	if (IS_ENCRYPTED(inode)) {
632 		int err = fscrypt_get_encryption_info(inode, false);
633 
634 		if (err)
635 			return err;
636 		if (!fscrypt_has_encryption_key(inode))
637 			return -ENOKEY;
638 	}
639 	return 0;
640 }
641 
642 /* keysetup_v1.c */
643 
644 void fscrypt_put_direct_key(struct fscrypt_direct_key *dk);
645 
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);
650 
651 /* policy.c */
652 
653 bool fscrypt_policies_equal(const union fscrypt_policy *policy1,
654 			    const union fscrypt_policy *policy2);
655 int fscrypt_policy_to_key_spec(const union fscrypt_policy *policy,
656 			       struct fscrypt_key_specifier *key_spec);
657 const union fscrypt_policy *fscrypt_get_dummy_policy(struct super_block *sb);
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);
663 const union fscrypt_policy *fscrypt_policy_to_inherit(struct inode *dir);
664 
665 #endif /* _FSCRYPT_PRIVATE_H */
666