1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Key setup facility for FS encryption support.
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 #include <crypto/skcipher.h>
12 #include <linux/key.h>
13
14 #include "fscrypt_private.h"
15
16 struct fscrypt_mode fscrypt_modes[] = {
17 [FSCRYPT_MODE_AES_256_XTS] = {
18 .friendly_name = "AES-256-XTS",
19 .cipher_str = "xts(aes)",
20 .keysize = 64,
21 .ivsize = 16,
22 .blk_crypto_mode = BLK_ENCRYPTION_MODE_AES_256_XTS,
23 },
24 [FSCRYPT_MODE_AES_256_CTS] = {
25 .friendly_name = "AES-256-CTS-CBC",
26 .cipher_str = "cts(cbc(aes))",
27 .keysize = 32,
28 .ivsize = 16,
29 },
30 [FSCRYPT_MODE_AES_128_CBC] = {
31 .friendly_name = "AES-128-CBC-ESSIV",
32 .cipher_str = "essiv(cbc(aes),sha256)",
33 .keysize = 16,
34 .ivsize = 16,
35 .blk_crypto_mode = BLK_ENCRYPTION_MODE_AES_128_CBC_ESSIV,
36 },
37 [FSCRYPT_MODE_AES_128_CTS] = {
38 .friendly_name = "AES-128-CTS-CBC",
39 .cipher_str = "cts(cbc(aes))",
40 .keysize = 16,
41 .ivsize = 16,
42 },
43 [FSCRYPT_MODE_ADIANTUM] = {
44 .friendly_name = "Adiantum",
45 .cipher_str = "adiantum(xchacha12,aes)",
46 .keysize = 32,
47 .ivsize = 32,
48 .blk_crypto_mode = BLK_ENCRYPTION_MODE_ADIANTUM,
49 },
50 };
51
52 static struct fscrypt_mode *
select_encryption_mode(const union fscrypt_policy * policy,const struct inode * inode)53 select_encryption_mode(const union fscrypt_policy *policy,
54 const struct inode *inode)
55 {
56 if (S_ISREG(inode->i_mode))
57 return &fscrypt_modes[fscrypt_policy_contents_mode(policy)];
58
59 if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
60 return &fscrypt_modes[fscrypt_policy_fnames_mode(policy)];
61
62 WARN_ONCE(1, "fscrypt: filesystem tried to load encryption info for inode %lu, which is not encryptable (file type %d)\n",
63 inode->i_ino, (inode->i_mode & S_IFMT));
64 return ERR_PTR(-EINVAL);
65 }
66
67 /* Create a symmetric cipher object for the given encryption mode and key */
68 static struct crypto_skcipher *
fscrypt_allocate_skcipher(struct fscrypt_mode * mode,const u8 * raw_key,const struct inode * inode)69 fscrypt_allocate_skcipher(struct fscrypt_mode *mode, const u8 *raw_key,
70 const struct inode *inode)
71 {
72 struct crypto_skcipher *tfm;
73 int err;
74
75 tfm = crypto_alloc_skcipher(mode->cipher_str, 0, 0);
76 if (IS_ERR(tfm)) {
77 if (PTR_ERR(tfm) == -ENOENT) {
78 fscrypt_warn(inode,
79 "Missing crypto API support for %s (API name: \"%s\")",
80 mode->friendly_name, mode->cipher_str);
81 return ERR_PTR(-ENOPKG);
82 }
83 fscrypt_err(inode, "Error allocating '%s' transform: %ld",
84 mode->cipher_str, PTR_ERR(tfm));
85 return tfm;
86 }
87 if (!xchg(&mode->logged_impl_name, 1)) {
88 /*
89 * fscrypt performance can vary greatly depending on which
90 * crypto algorithm implementation is used. Help people debug
91 * performance problems by logging the ->cra_driver_name the
92 * first time a mode is used.
93 */
94 pr_info("fscrypt: %s using implementation \"%s\"\n",
95 mode->friendly_name,
96 crypto_skcipher_alg(tfm)->base.cra_driver_name);
97 }
98 crypto_skcipher_set_flags(tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
99 err = crypto_skcipher_setkey(tfm, raw_key, mode->keysize);
100 if (err)
101 goto err_free_tfm;
102
103 return tfm;
104
105 err_free_tfm:
106 crypto_free_skcipher(tfm);
107 return ERR_PTR(err);
108 }
109
110 /*
111 * Prepare the crypto transform object or blk-crypto key in @prep_key, given the
112 * raw key, encryption mode, and flag indicating which encryption implementation
113 * (fs-layer or blk-crypto) will be used.
114 */
fscrypt_prepare_key(struct fscrypt_prepared_key * prep_key,const u8 * raw_key,unsigned int raw_key_size,const struct fscrypt_info * ci)115 int fscrypt_prepare_key(struct fscrypt_prepared_key *prep_key,
116 const u8 *raw_key, unsigned int raw_key_size,
117 const struct fscrypt_info *ci)
118 {
119 struct crypto_skcipher *tfm;
120
121 if (fscrypt_using_inline_encryption(ci))
122 return fscrypt_prepare_inline_crypt_key(prep_key,
123 raw_key, raw_key_size, ci);
124
125 if (WARN_ON(raw_key_size != ci->ci_mode->keysize))
126 return -EINVAL;
127
128 tfm = fscrypt_allocate_skcipher(ci->ci_mode, raw_key, ci->ci_inode);
129 if (IS_ERR(tfm))
130 return PTR_ERR(tfm);
131 /*
132 * Pairs with READ_ONCE() in fscrypt_is_key_prepared(). (Only matters
133 * for the per-mode keys, which are shared by multiple inodes.)
134 */
135 smp_store_release(&prep_key->tfm, tfm);
136 return 0;
137 }
138
139 /* Destroy a crypto transform object and/or blk-crypto key. */
fscrypt_destroy_prepared_key(struct fscrypt_prepared_key * prep_key)140 void fscrypt_destroy_prepared_key(struct fscrypt_prepared_key *prep_key)
141 {
142 crypto_free_skcipher(prep_key->tfm);
143 fscrypt_destroy_inline_crypt_key(prep_key);
144 }
145
146 /* Given the per-file key, set up the file's crypto transform object */
fscrypt_set_derived_key(struct fscrypt_info * ci,const u8 * derived_key)147 int fscrypt_set_derived_key(struct fscrypt_info *ci, const u8 *derived_key)
148 {
149 ci->ci_owns_key = true;
150 return fscrypt_prepare_key(&ci->ci_key, derived_key,
151 ci->ci_mode->keysize, ci);
152 }
153
setup_per_mode_key(struct fscrypt_info * ci,struct fscrypt_master_key * mk,struct fscrypt_prepared_key * keys,u8 hkdf_context,bool include_fs_uuid)154 static int setup_per_mode_key(struct fscrypt_info *ci,
155 struct fscrypt_master_key *mk,
156 struct fscrypt_prepared_key *keys,
157 u8 hkdf_context, bool include_fs_uuid)
158 {
159 static DEFINE_MUTEX(mode_key_setup_mutex);
160 const struct inode *inode = ci->ci_inode;
161 const struct super_block *sb = inode->i_sb;
162 struct fscrypt_mode *mode = ci->ci_mode;
163 const u8 mode_num = mode - fscrypt_modes;
164 struct fscrypt_prepared_key *prep_key;
165 u8 mode_key[FSCRYPT_MAX_KEY_SIZE];
166 u8 hkdf_info[sizeof(mode_num) + sizeof(sb->s_uuid)];
167 unsigned int hkdf_infolen = 0;
168 int err;
169
170 if (WARN_ON(mode_num > __FSCRYPT_MODE_MAX))
171 return -EINVAL;
172
173 prep_key = &keys[mode_num];
174 if (fscrypt_is_key_prepared(prep_key, ci)) {
175 ci->ci_key = *prep_key;
176 return 0;
177 }
178
179 mutex_lock(&mode_key_setup_mutex);
180
181 if (fscrypt_is_key_prepared(prep_key, ci))
182 goto done_unlock;
183
184 if (mk->mk_secret.is_hw_wrapped && S_ISREG(inode->i_mode)) {
185 int i;
186
187 if (!fscrypt_using_inline_encryption(ci)) {
188 fscrypt_warn(ci->ci_inode,
189 "Hardware-wrapped keys require inline encryption (-o inlinecrypt)");
190 err = -EINVAL;
191 goto out_unlock;
192 }
193 for (i = 0; i <= __FSCRYPT_MODE_MAX; i++) {
194 if (fscrypt_is_key_prepared(&keys[i], ci)) {
195 fscrypt_warn(ci->ci_inode,
196 "Each hardware-wrapped key can only be used with one encryption mode");
197 err = -EINVAL;
198 goto out_unlock;
199 }
200 }
201 err = fscrypt_prepare_key(prep_key, mk->mk_secret.raw,
202 mk->mk_secret.size, ci);
203 if (err)
204 goto out_unlock;
205 } else {
206 BUILD_BUG_ON(sizeof(mode_num) != 1);
207 BUILD_BUG_ON(sizeof(sb->s_uuid) != 16);
208 BUILD_BUG_ON(sizeof(hkdf_info) != 17);
209 hkdf_info[hkdf_infolen++] = mode_num;
210 if (include_fs_uuid) {
211 memcpy(&hkdf_info[hkdf_infolen], &sb->s_uuid,
212 sizeof(sb->s_uuid));
213 hkdf_infolen += sizeof(sb->s_uuid);
214 }
215 err = fscrypt_hkdf_expand(&mk->mk_secret.hkdf,
216 hkdf_context, hkdf_info, hkdf_infolen,
217 mode_key, mode->keysize);
218 if (err)
219 goto out_unlock;
220 err = fscrypt_prepare_key(prep_key, mode_key, mode->keysize,
221 ci);
222 memzero_explicit(mode_key, mode->keysize);
223 if (err)
224 goto out_unlock;
225 }
226 done_unlock:
227 ci->ci_key = *prep_key;
228 err = 0;
229 out_unlock:
230 mutex_unlock(&mode_key_setup_mutex);
231 return err;
232 }
233
fscrypt_setup_v2_file_key(struct fscrypt_info * ci,struct fscrypt_master_key * mk)234 static int fscrypt_setup_v2_file_key(struct fscrypt_info *ci,
235 struct fscrypt_master_key *mk)
236 {
237 u8 derived_key[FSCRYPT_MAX_KEY_SIZE];
238 int err;
239
240 if (mk->mk_secret.is_hw_wrapped &&
241 !(ci->ci_policy.v2.flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64)) {
242 fscrypt_warn(ci->ci_inode,
243 "Hardware-wrapped keys are only supported with IV_INO_LBLK_64 policies");
244 return -EINVAL;
245 }
246
247 if (ci->ci_policy.v2.flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) {
248 /*
249 * DIRECT_KEY: instead of deriving per-file keys, the per-file
250 * nonce will be included in all the IVs. But unlike v1
251 * policies, for v2 policies in this case we don't encrypt with
252 * the master key directly but rather derive a per-mode key.
253 * This ensures that the master key is consistently used only
254 * for HKDF, avoiding key reuse issues.
255 */
256 if (!fscrypt_mode_supports_direct_key(ci->ci_mode)) {
257 fscrypt_warn(ci->ci_inode,
258 "Direct key flag not allowed with %s",
259 ci->ci_mode->friendly_name);
260 return -EINVAL;
261 }
262 return setup_per_mode_key(ci, mk, mk->mk_direct_keys,
263 HKDF_CONTEXT_DIRECT_KEY, false);
264 } else if (ci->ci_policy.v2.flags &
265 FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) {
266 /*
267 * IV_INO_LBLK_64: encryption keys are derived from (master_key,
268 * mode_num, filesystem_uuid), and inode number is included in
269 * the IVs. This format is optimized for use with inline
270 * encryption hardware compliant with the UFS or eMMC standards.
271 */
272 return setup_per_mode_key(ci, mk, mk->mk_iv_ino_lblk_64_keys,
273 HKDF_CONTEXT_IV_INO_LBLK_64_KEY,
274 true);
275 }
276
277 err = fscrypt_hkdf_expand(&mk->mk_secret.hkdf,
278 HKDF_CONTEXT_PER_FILE_KEY,
279 ci->ci_nonce, FS_KEY_DERIVATION_NONCE_SIZE,
280 derived_key, ci->ci_mode->keysize);
281 if (err)
282 return err;
283
284 err = fscrypt_set_derived_key(ci, derived_key);
285 memzero_explicit(derived_key, ci->ci_mode->keysize);
286 return err;
287 }
288
289 /*
290 * Find the master key, then set up the inode's actual encryption key.
291 *
292 * If the master key is found in the filesystem-level keyring, then the
293 * corresponding 'struct key' is returned in *master_key_ret with
294 * ->mk_secret_sem read-locked. This is needed to ensure that only one task
295 * links the fscrypt_info into ->mk_decrypted_inodes (as multiple tasks may race
296 * to create an fscrypt_info for the same inode), and to synchronize the master
297 * key being removed with a new inode starting to use it.
298 */
setup_file_encryption_key(struct fscrypt_info * ci,struct key ** master_key_ret)299 static int setup_file_encryption_key(struct fscrypt_info *ci,
300 struct key **master_key_ret)
301 {
302 struct key *key;
303 struct fscrypt_master_key *mk = NULL;
304 struct fscrypt_key_specifier mk_spec;
305 int err;
306
307 fscrypt_select_encryption_impl(ci);
308
309 switch (ci->ci_policy.version) {
310 case FSCRYPT_POLICY_V1:
311 mk_spec.type = FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR;
312 memcpy(mk_spec.u.descriptor,
313 ci->ci_policy.v1.master_key_descriptor,
314 FSCRYPT_KEY_DESCRIPTOR_SIZE);
315 break;
316 case FSCRYPT_POLICY_V2:
317 mk_spec.type = FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER;
318 memcpy(mk_spec.u.identifier,
319 ci->ci_policy.v2.master_key_identifier,
320 FSCRYPT_KEY_IDENTIFIER_SIZE);
321 break;
322 default:
323 WARN_ON(1);
324 return -EINVAL;
325 }
326
327 key = fscrypt_find_master_key(ci->ci_inode->i_sb, &mk_spec);
328 if (IS_ERR(key)) {
329 if (key != ERR_PTR(-ENOKEY) ||
330 ci->ci_policy.version != FSCRYPT_POLICY_V1)
331 return PTR_ERR(key);
332
333 /*
334 * As a legacy fallback for v1 policies, search for the key in
335 * the current task's subscribed keyrings too. Don't move this
336 * to before the search of ->s_master_keys, since users
337 * shouldn't be able to override filesystem-level keys.
338 */
339 return fscrypt_setup_v1_file_key_via_subscribed_keyrings(ci);
340 }
341
342 mk = key->payload.data[0];
343 down_read(&mk->mk_secret_sem);
344
345 /* Has the secret been removed (via FS_IOC_REMOVE_ENCRYPTION_KEY)? */
346 if (!is_master_key_secret_present(&mk->mk_secret)) {
347 err = -ENOKEY;
348 goto out_release_key;
349 }
350
351 /*
352 * Require that the master key be at least as long as the derived key.
353 * Otherwise, the derived key cannot possibly contain as much entropy as
354 * that required by the encryption mode it will be used for. For v1
355 * policies it's also required for the KDF to work at all.
356 */
357 if (mk->mk_secret.size < ci->ci_mode->keysize) {
358 fscrypt_warn(NULL,
359 "key with %s %*phN is too short (got %u bytes, need %u+ bytes)",
360 master_key_spec_type(&mk_spec),
361 master_key_spec_len(&mk_spec), (u8 *)&mk_spec.u,
362 mk->mk_secret.size, ci->ci_mode->keysize);
363 err = -ENOKEY;
364 goto out_release_key;
365 }
366
367 switch (ci->ci_policy.version) {
368 case FSCRYPT_POLICY_V1:
369 err = fscrypt_setup_v1_file_key(ci, mk->mk_secret.raw);
370 break;
371 case FSCRYPT_POLICY_V2:
372 err = fscrypt_setup_v2_file_key(ci, mk);
373 break;
374 default:
375 WARN_ON(1);
376 err = -EINVAL;
377 break;
378 }
379 if (err)
380 goto out_release_key;
381
382 *master_key_ret = key;
383 return 0;
384
385 out_release_key:
386 up_read(&mk->mk_secret_sem);
387 key_put(key);
388 return err;
389 }
390
put_crypt_info(struct fscrypt_info * ci)391 static void put_crypt_info(struct fscrypt_info *ci)
392 {
393 struct key *key;
394
395 if (!ci)
396 return;
397
398 if (ci->ci_direct_key)
399 fscrypt_put_direct_key(ci->ci_direct_key);
400 else if (ci->ci_owns_key)
401 fscrypt_destroy_prepared_key(&ci->ci_key);
402
403 key = ci->ci_master_key;
404 if (key) {
405 struct fscrypt_master_key *mk = key->payload.data[0];
406
407 /*
408 * Remove this inode from the list of inodes that were unlocked
409 * with the master key.
410 *
411 * In addition, if we're removing the last inode from a key that
412 * already had its secret removed, invalidate the key so that it
413 * gets removed from ->s_master_keys.
414 */
415 spin_lock(&mk->mk_decrypted_inodes_lock);
416 list_del(&ci->ci_master_key_link);
417 spin_unlock(&mk->mk_decrypted_inodes_lock);
418 if (refcount_dec_and_test(&mk->mk_refcount))
419 key_invalidate(key);
420 key_put(key);
421 }
422 memzero_explicit(ci, sizeof(*ci));
423 kmem_cache_free(fscrypt_info_cachep, ci);
424 }
425
fscrypt_get_encryption_info(struct inode * inode)426 int fscrypt_get_encryption_info(struct inode *inode)
427 {
428 struct fscrypt_info *crypt_info;
429 union fscrypt_context ctx;
430 struct fscrypt_mode *mode;
431 struct key *master_key = NULL;
432 int res;
433
434 if (fscrypt_has_encryption_key(inode))
435 return 0;
436
437 res = fscrypt_initialize(inode->i_sb->s_cop->flags);
438 if (res)
439 return res;
440
441 res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
442 if (res < 0) {
443 if (!fscrypt_dummy_context_enabled(inode) ||
444 IS_ENCRYPTED(inode)) {
445 fscrypt_warn(inode,
446 "Error %d getting encryption context",
447 res);
448 return res;
449 }
450 /* Fake up a context for an unencrypted directory */
451 memset(&ctx, 0, sizeof(ctx));
452 ctx.version = FSCRYPT_CONTEXT_V1;
453 ctx.v1.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS;
454 ctx.v1.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS;
455 memset(ctx.v1.master_key_descriptor, 0x42,
456 FSCRYPT_KEY_DESCRIPTOR_SIZE);
457 res = sizeof(ctx.v1);
458 }
459
460 crypt_info = kmem_cache_zalloc(fscrypt_info_cachep, GFP_NOFS);
461 if (!crypt_info)
462 return -ENOMEM;
463
464 crypt_info->ci_inode = inode;
465
466 res = fscrypt_policy_from_context(&crypt_info->ci_policy, &ctx, res);
467 if (res) {
468 fscrypt_warn(inode,
469 "Unrecognized or corrupt encryption context");
470 goto out;
471 }
472
473 switch (ctx.version) {
474 case FSCRYPT_CONTEXT_V1:
475 memcpy(crypt_info->ci_nonce, ctx.v1.nonce,
476 FS_KEY_DERIVATION_NONCE_SIZE);
477 break;
478 case FSCRYPT_CONTEXT_V2:
479 memcpy(crypt_info->ci_nonce, ctx.v2.nonce,
480 FS_KEY_DERIVATION_NONCE_SIZE);
481 break;
482 default:
483 WARN_ON(1);
484 res = -EINVAL;
485 goto out;
486 }
487
488 if (!fscrypt_supported_policy(&crypt_info->ci_policy, inode)) {
489 res = -EINVAL;
490 goto out;
491 }
492
493 mode = select_encryption_mode(&crypt_info->ci_policy, inode);
494 if (IS_ERR(mode)) {
495 res = PTR_ERR(mode);
496 goto out;
497 }
498 WARN_ON(mode->ivsize > FSCRYPT_MAX_IV_SIZE);
499 crypt_info->ci_mode = mode;
500
501 res = setup_file_encryption_key(crypt_info, &master_key);
502 if (res)
503 goto out;
504
505 if (cmpxchg_release(&inode->i_crypt_info, NULL, crypt_info) == NULL) {
506 if (master_key) {
507 struct fscrypt_master_key *mk =
508 master_key->payload.data[0];
509
510 refcount_inc(&mk->mk_refcount);
511 crypt_info->ci_master_key = key_get(master_key);
512 spin_lock(&mk->mk_decrypted_inodes_lock);
513 list_add(&crypt_info->ci_master_key_link,
514 &mk->mk_decrypted_inodes);
515 spin_unlock(&mk->mk_decrypted_inodes_lock);
516 }
517 crypt_info = NULL;
518 }
519 res = 0;
520 out:
521 if (master_key) {
522 struct fscrypt_master_key *mk = master_key->payload.data[0];
523
524 up_read(&mk->mk_secret_sem);
525 key_put(master_key);
526 }
527 if (res == -ENOKEY)
528 res = 0;
529 put_crypt_info(crypt_info);
530 return res;
531 }
532 EXPORT_SYMBOL(fscrypt_get_encryption_info);
533
534 /**
535 * fscrypt_put_encryption_info - free most of an inode's fscrypt data
536 *
537 * Free the inode's fscrypt_info. Filesystems must call this when the inode is
538 * being evicted. An RCU grace period need not have elapsed yet.
539 */
fscrypt_put_encryption_info(struct inode * inode)540 void fscrypt_put_encryption_info(struct inode *inode)
541 {
542 put_crypt_info(inode->i_crypt_info);
543 inode->i_crypt_info = NULL;
544 }
545 EXPORT_SYMBOL(fscrypt_put_encryption_info);
546
547 /**
548 * fscrypt_free_inode - free an inode's fscrypt data requiring RCU delay
549 *
550 * Free the inode's cached decrypted symlink target, if any. Filesystems must
551 * call this after an RCU grace period, just before they free the inode.
552 */
fscrypt_free_inode(struct inode * inode)553 void fscrypt_free_inode(struct inode *inode)
554 {
555 if (IS_ENCRYPTED(inode) && S_ISLNK(inode->i_mode)) {
556 kfree(inode->i_link);
557 inode->i_link = NULL;
558 }
559 }
560 EXPORT_SYMBOL(fscrypt_free_inode);
561
562 /**
563 * fscrypt_drop_inode - check whether the inode's master key has been removed
564 *
565 * Filesystems supporting fscrypt must call this from their ->drop_inode()
566 * method so that encrypted inodes are evicted as soon as they're no longer in
567 * use and their master key has been removed.
568 *
569 * Return: 1 if fscrypt wants the inode to be evicted now, otherwise 0
570 */
fscrypt_drop_inode(struct inode * inode)571 int fscrypt_drop_inode(struct inode *inode)
572 {
573 const struct fscrypt_info *ci = READ_ONCE(inode->i_crypt_info);
574 const struct fscrypt_master_key *mk;
575
576 /*
577 * If ci is NULL, then the inode doesn't have an encryption key set up
578 * so it's irrelevant. If ci_master_key is NULL, then the master key
579 * was provided via the legacy mechanism of the process-subscribed
580 * keyrings, so we don't know whether it's been removed or not.
581 */
582 if (!ci || !ci->ci_master_key)
583 return 0;
584 mk = ci->ci_master_key->payload.data[0];
585
586 /*
587 * Note: since we aren't holding ->mk_secret_sem, the result here can
588 * immediately become outdated. But there's no correctness problem with
589 * unnecessarily evicting. Nor is there a correctness problem with not
590 * evicting while iput() is racing with the key being removed, since
591 * then the thread removing the key will either evict the inode itself
592 * or will correctly detect that it wasn't evicted due to the race.
593 */
594 return !is_master_key_secret_present(&mk->mk_secret);
595 }
596 EXPORT_SYMBOL_GPL(fscrypt_drop_inode);
597