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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/*
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 __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 */
65union 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 */
75static 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 */
89static 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 */
96static 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(1);
105 return NULL;
106}
107
108union 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 */
118static 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 */
130static inline u8
131fscrypt_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 */
143static inline u8
144fscrypt_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 */
156static inline u8
157fscrypt_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 */
172struct fscrypt_symlink_data {
173 __le16 len;
174 char encrypted_path[1];
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 */
184struct 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 */
198struct 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
260typedef enum {
261 FS_DECRYPT = 0,
262 FS_ENCRYPT,
263} fscrypt_direction_t;
264
265/* crypto.c */
266extern struct kmem_cache *fscrypt_info_cachep;
267int fscrypt_initialize(unsigned int cop_flags);
268int 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);
272struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags);
273
274void __printf(3, 4) __cold
275fscrypt_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
284union 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
296void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num,
297 const struct fscrypt_info *ci);
298
299/* fname.c */
300bool __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 */
305struct fscrypt_hkdf {
306 struct crypto_shash *hmac_tfm;
307};
308
309int 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
327int fscrypt_hkdf_expand(const struct fscrypt_hkdf *hkdf, u8 context,
328 const u8 *info, unsigned int infolen,
329 u8 *okm, unsigned int okmlen);
330
331void fscrypt_destroy_hkdf(struct fscrypt_hkdf *hkdf);
332
333/* inline_crypt.c */
334#ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT
335int fscrypt_select_encryption_impl(struct fscrypt_info *ci);
336
337static inline bool
338fscrypt_using_inline_encryption(const struct fscrypt_info *ci)
339{
340 return ci->ci_inlinecrypt;
341}
342
343int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key,
344 const u8 *raw_key,
345 const struct fscrypt_info *ci);
346
347void 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 */
354static inline bool
355fscrypt_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
373static inline int fscrypt_select_encryption_impl(struct fscrypt_info *ci)
374{
375 return 0;
376}
377
378static inline bool
379fscrypt_using_inline_encryption(const struct fscrypt_info *ci)
380{
381 return false;
382}
383
384static inline int
385fscrypt_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(1);
390 return -EOPNOTSUPP;
391}
392
393static inline void
394fscrypt_destroy_inline_crypt_key(struct super_block *sb,
395 struct fscrypt_prepared_key *prep_key)
396{
397}
398
399static inline bool
400fscrypt_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 */
412struct 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 */
439struct 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
528static inline bool
529is_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
541static 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
553static 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
564void fscrypt_put_master_key(struct fscrypt_master_key *mk);
565
566void fscrypt_put_master_key_activeref(struct super_block *sb,
567 struct fscrypt_master_key *mk);
568
569struct fscrypt_master_key *
570fscrypt_find_master_key(struct super_block *sb,
571 const struct fscrypt_key_specifier *mk_spec);
572
573int fscrypt_get_test_dummy_key_identifier(
574 u8 key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]);
575
576int fscrypt_verify_key_added(struct super_block *sb,
577 const u8 identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]);
578
579int __init fscrypt_init_keyring(void);
580
581/* keysetup.c */
582
583struct fscrypt_mode {
584 const char *friendly_name;
585 const char *cipher_str;
586 int keysize; /* key size in bytes */
587 int security_strength; /* security strength in bytes */
588 int ivsize; /* IV size in bytes */
589 int logged_cryptoapi_impl;
590 int logged_blk_crypto_native;
591 int logged_blk_crypto_fallback;
592 enum blk_crypto_mode_num blk_crypto_mode;
593};
594
595extern struct fscrypt_mode fscrypt_modes[];
596
597int fscrypt_prepare_key(struct fscrypt_prepared_key *prep_key,
598 const u8 *raw_key, const struct fscrypt_info *ci);
599
600void fscrypt_destroy_prepared_key(struct super_block *sb,
601 struct fscrypt_prepared_key *prep_key);
602
603int fscrypt_set_per_file_enc_key(struct fscrypt_info *ci, const u8 *raw_key);
604
605int fscrypt_derive_dirhash_key(struct fscrypt_info *ci,
606 const struct fscrypt_master_key *mk);
607
608void fscrypt_hash_inode_number(struct fscrypt_info *ci,
609 const struct fscrypt_master_key *mk);
610
611int fscrypt_get_encryption_info(struct inode *inode, bool allow_unsupported);
612
613/**
614 * fscrypt_require_key() - require an inode's encryption key
615 * @inode: the inode we need the key for
616 *
617 * If the inode is encrypted, set up its encryption key if not already done.
618 * Then require that the key be present and return -ENOKEY otherwise.
619 *
620 * No locks are needed, and the key will live as long as the struct inode --- so
621 * it won't go away from under you.
622 *
623 * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code
624 * if a problem occurred while setting up the encryption key.
625 */
626static inline int fscrypt_require_key(struct inode *inode)
627{
628 if (IS_ENCRYPTED(inode)) {
629 int err = fscrypt_get_encryption_info(inode, false);
630
631 if (err)
632 return err;
633 if (!fscrypt_has_encryption_key(inode))
634 return -ENOKEY;
635 }
636 return 0;
637}
638
639/* keysetup_v1.c */
640
641void fscrypt_put_direct_key(struct fscrypt_direct_key *dk);
642
643int fscrypt_setup_v1_file_key(struct fscrypt_info *ci,
644 const u8 *raw_master_key);
645
646int fscrypt_setup_v1_file_key_via_subscribed_keyrings(struct fscrypt_info *ci);
647
648/* policy.c */
649
650bool fscrypt_policies_equal(const union fscrypt_policy *policy1,
651 const union fscrypt_policy *policy2);
652int fscrypt_policy_to_key_spec(const union fscrypt_policy *policy,
653 struct fscrypt_key_specifier *key_spec);
654bool fscrypt_supported_policy(const union fscrypt_policy *policy_u,
655 const struct inode *inode);
656int fscrypt_policy_from_context(union fscrypt_policy *policy_u,
657 const union fscrypt_context *ctx_u,
658 int ctx_size);
659const union fscrypt_policy *fscrypt_policy_to_inherit(struct inode *dir);
660
661#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 * This contains encryption key functions.
8 *
9 * Written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar, 2015.
10 */
11
12#ifndef _FSCRYPT_PRIVATE_H
13#define _FSCRYPT_PRIVATE_H
14
15#define __FS_HAS_ENCRYPTION 1
16#include <linux/fscrypt.h>
17#include <crypto/hash.h>
18
19/* Encryption parameters */
20#define FS_IV_SIZE 16
21#define FS_AES_128_ECB_KEY_SIZE 16
22#define FS_AES_128_CBC_KEY_SIZE 16
23#define FS_AES_128_CTS_KEY_SIZE 16
24#define FS_AES_256_GCM_KEY_SIZE 32
25#define FS_AES_256_CBC_KEY_SIZE 32
26#define FS_AES_256_CTS_KEY_SIZE 32
27#define FS_AES_256_XTS_KEY_SIZE 64
28
29#define FS_KEY_DERIVATION_NONCE_SIZE 16
30
31/**
32 * Encryption context for inode
33 *
34 * Protector format:
35 * 1 byte: Protector format (1 = this version)
36 * 1 byte: File contents encryption mode
37 * 1 byte: File names encryption mode
38 * 1 byte: Flags
39 * 8 bytes: Master Key descriptor
40 * 16 bytes: Encryption Key derivation nonce
41 */
42struct fscrypt_context {
43 u8 format;
44 u8 contents_encryption_mode;
45 u8 filenames_encryption_mode;
46 u8 flags;
47 u8 master_key_descriptor[FS_KEY_DESCRIPTOR_SIZE];
48 u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
49} __packed;
50
51#define FS_ENCRYPTION_CONTEXT_FORMAT_V1 1
52
53/**
54 * For encrypted symlinks, the ciphertext length is stored at the beginning
55 * of the string in little-endian format.
56 */
57struct fscrypt_symlink_data {
58 __le16 len;
59 char encrypted_path[1];
60} __packed;
61
62/*
63 * A pointer to this structure is stored in the file system's in-core
64 * representation of an inode.
65 */
66struct fscrypt_info {
67 u8 ci_data_mode;
68 u8 ci_filename_mode;
69 u8 ci_flags;
70 struct crypto_skcipher *ci_ctfm;
71 struct crypto_cipher *ci_essiv_tfm;
72 u8 ci_master_key[FS_KEY_DESCRIPTOR_SIZE];
73};
74
75typedef enum {
76 FS_DECRYPT = 0,
77 FS_ENCRYPT,
78} fscrypt_direction_t;
79
80#define FS_CTX_REQUIRES_FREE_ENCRYPT_FL 0x00000001
81#define FS_CTX_HAS_BOUNCE_BUFFER_FL 0x00000002
82
83static inline bool fscrypt_valid_enc_modes(u32 contents_mode,
84 u32 filenames_mode)
85{
86 if (contents_mode == FS_ENCRYPTION_MODE_AES_128_CBC &&
87 filenames_mode == FS_ENCRYPTION_MODE_AES_128_CTS)
88 return true;
89
90 if (contents_mode == FS_ENCRYPTION_MODE_AES_256_XTS &&
91 filenames_mode == FS_ENCRYPTION_MODE_AES_256_CTS)
92 return true;
93
94 return false;
95}
96
97/* crypto.c */
98extern struct kmem_cache *fscrypt_info_cachep;
99extern int fscrypt_initialize(unsigned int cop_flags);
100extern struct workqueue_struct *fscrypt_read_workqueue;
101extern int fscrypt_do_page_crypto(const struct inode *inode,
102 fscrypt_direction_t rw, u64 lblk_num,
103 struct page *src_page,
104 struct page *dest_page,
105 unsigned int len, unsigned int offs,
106 gfp_t gfp_flags);
107extern struct page *fscrypt_alloc_bounce_page(struct fscrypt_ctx *ctx,
108 gfp_t gfp_flags);
109
110/* fname.c */
111extern int fname_encrypt(struct inode *inode, const struct qstr *iname,
112 u8 *out, unsigned int olen);
113extern bool fscrypt_fname_encrypted_size(const struct inode *inode,
114 u32 orig_len, u32 max_len,
115 u32 *encrypted_len_ret);
116
117/* keyinfo.c */
118extern void __exit fscrypt_essiv_cleanup(void);
119
120#endif /* _FSCRYPT_PRIVATE_H */