1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Filesystem-level keyring for fscrypt
4 *
5 * Copyright 2019 Google LLC
6 */
7
8/*
9 * This file implements management of fscrypt master keys in the
10 * filesystem-level keyring, including the ioctls:
11 *
12 * - FS_IOC_ADD_ENCRYPTION_KEY
13 * - FS_IOC_REMOVE_ENCRYPTION_KEY
14 * - FS_IOC_REMOVE_ENCRYPTION_KEY_ALL_USERS
15 * - FS_IOC_GET_ENCRYPTION_KEY_STATUS
16 *
17 * See the "User API" section of Documentation/filesystems/fscrypt.rst for more
18 * information about these ioctls.
19 */
20
21#include <crypto/skcipher.h>
22#include <linux/export.h>
23#include <linux/key-type.h>
24#include <linux/once.h>
25#include <linux/random.h>
26#include <linux/seq_file.h>
27#include <linux/unaligned.h>
28
29#include "fscrypt_private.h"
30
31/* The master encryption keys for a filesystem (->s_master_keys) */
32struct fscrypt_keyring {
33 /*
34 * Lock that protects ->key_hashtable. It does *not* protect the
35 * fscrypt_master_key structs themselves.
36 */
37 spinlock_t lock;
38
39 /* Hash table that maps fscrypt_key_specifier to fscrypt_master_key */
40 struct hlist_head key_hashtable[128];
41};
42
43static void wipe_master_key_secret(struct fscrypt_master_key_secret *secret)
44{
45 memzero_explicit(s: secret, count: sizeof(*secret));
46}
47
48static void move_master_key_secret(struct fscrypt_master_key_secret *dst,
49 struct fscrypt_master_key_secret *src)
50{
51 memcpy(dst, src, sizeof(*dst));
52 memzero_explicit(s: src, count: sizeof(*src));
53}
54
55static void fscrypt_free_master_key(struct rcu_head *head)
56{
57 struct fscrypt_master_key *mk =
58 container_of(head, struct fscrypt_master_key, mk_rcu_head);
59 /*
60 * The master key secret and any embedded subkeys should have already
61 * been wiped when the last active reference to the fscrypt_master_key
62 * struct was dropped; doing it here would be unnecessarily late.
63 * Nevertheless, use kfree_sensitive() in case anything was missed.
64 */
65 kfree_sensitive(objp: mk);
66}
67
68void fscrypt_put_master_key(struct fscrypt_master_key *mk)
69{
70 if (!refcount_dec_and_test(r: &mk->mk_struct_refs))
71 return;
72 /*
73 * No structural references left, so free ->mk_users, and also free the
74 * fscrypt_master_key struct itself after an RCU grace period ensures
75 * that concurrent keyring lookups can no longer find it.
76 */
77 WARN_ON_ONCE(refcount_read(&mk->mk_active_refs) != 0);
78 if (mk->mk_users) {
79 /* Clear the keyring so the quota gets released right away. */
80 keyring_clear(keyring: mk->mk_users);
81 key_put(key: mk->mk_users);
82 mk->mk_users = NULL;
83 }
84 call_rcu(head: &mk->mk_rcu_head, func: fscrypt_free_master_key);
85}
86
87void fscrypt_put_master_key_activeref(struct super_block *sb,
88 struct fscrypt_master_key *mk)
89{
90 size_t i;
91
92 if (!refcount_dec_and_test(r: &mk->mk_active_refs))
93 return;
94 /*
95 * No active references left, so complete the full removal of this
96 * fscrypt_master_key struct by removing it from the keyring and
97 * destroying any subkeys embedded in it.
98 */
99
100 if (WARN_ON_ONCE(!sb->s_master_keys))
101 return;
102 spin_lock(lock: &sb->s_master_keys->lock);
103 hlist_del_rcu(n: &mk->mk_node);
104 spin_unlock(lock: &sb->s_master_keys->lock);
105
106 /*
107 * ->mk_active_refs == 0 implies that ->mk_present is false and
108 * ->mk_decrypted_inodes is empty.
109 */
110 WARN_ON_ONCE(mk->mk_present);
111 WARN_ON_ONCE(!list_empty(&mk->mk_decrypted_inodes));
112
113 for (i = 0; i <= FSCRYPT_MODE_MAX; i++) {
114 fscrypt_destroy_prepared_key(
115 sb, prep_key: &mk->mk_direct_keys[i]);
116 fscrypt_destroy_prepared_key(
117 sb, prep_key: &mk->mk_iv_ino_lblk_64_keys[i]);
118 fscrypt_destroy_prepared_key(
119 sb, prep_key: &mk->mk_iv_ino_lblk_32_keys[i]);
120 }
121 memzero_explicit(s: &mk->mk_ino_hash_key,
122 count: sizeof(mk->mk_ino_hash_key));
123 mk->mk_ino_hash_key_initialized = false;
124
125 /* Drop the structural ref associated with the active refs. */
126 fscrypt_put_master_key(mk);
127}
128
129/*
130 * This transitions the key state from present to incompletely removed, and then
131 * potentially to absent (depending on whether inodes remain).
132 */
133static void fscrypt_initiate_key_removal(struct super_block *sb,
134 struct fscrypt_master_key *mk)
135{
136 WRITE_ONCE(mk->mk_present, false);
137 wipe_master_key_secret(secret: &mk->mk_secret);
138 fscrypt_put_master_key_activeref(sb, mk);
139}
140
141static inline bool valid_key_spec(const struct fscrypt_key_specifier *spec)
142{
143 if (spec->__reserved)
144 return false;
145 return master_key_spec_len(spec) != 0;
146}
147
148static int fscrypt_user_key_instantiate(struct key *key,
149 struct key_preparsed_payload *prep)
150{
151 /*
152 * We just charge FSCRYPT_MAX_RAW_KEY_SIZE bytes to the user's key quota
153 * for each key, regardless of the exact key size. The amount of memory
154 * actually used is greater than the size of the raw key anyway.
155 */
156 return key_payload_reserve(key, FSCRYPT_MAX_RAW_KEY_SIZE);
157}
158
159static void fscrypt_user_key_describe(const struct key *key, struct seq_file *m)
160{
161 seq_puts(m, s: key->description);
162}
163
164/*
165 * Type of key in ->mk_users. Each key of this type represents a particular
166 * user who has added a particular master key.
167 *
168 * Note that the name of this key type really should be something like
169 * ".fscrypt-user" instead of simply ".fscrypt". But the shorter name is chosen
170 * mainly for simplicity of presentation in /proc/keys when read by a non-root
171 * user. And it is expected to be rare that a key is actually added by multiple
172 * users, since users should keep their encryption keys confidential.
173 */
174static struct key_type key_type_fscrypt_user = {
175 .name = ".fscrypt",
176 .instantiate = fscrypt_user_key_instantiate,
177 .describe = fscrypt_user_key_describe,
178};
179
180#define FSCRYPT_MK_USERS_DESCRIPTION_SIZE \
181 (CONST_STRLEN("fscrypt-") + 2 * FSCRYPT_KEY_IDENTIFIER_SIZE + \
182 CONST_STRLEN("-users") + 1)
183
184#define FSCRYPT_MK_USER_DESCRIPTION_SIZE \
185 (2 * FSCRYPT_KEY_IDENTIFIER_SIZE + CONST_STRLEN(".uid.") + 10 + 1)
186
187static void format_mk_users_keyring_description(
188 char description[FSCRYPT_MK_USERS_DESCRIPTION_SIZE],
189 const u8 mk_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE])
190{
191 sprintf(buf: description, fmt: "fscrypt-%*phN-users",
192 FSCRYPT_KEY_IDENTIFIER_SIZE, mk_identifier);
193}
194
195static void format_mk_user_description(
196 char description[FSCRYPT_MK_USER_DESCRIPTION_SIZE],
197 const u8 mk_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE])
198{
199
200 sprintf(buf: description, fmt: "%*phN.uid.%u", FSCRYPT_KEY_IDENTIFIER_SIZE,
201 mk_identifier, __kuid_val(current_fsuid()));
202}
203
204/* Create ->s_master_keys if needed. Synchronized by fscrypt_add_key_mutex. */
205static int allocate_filesystem_keyring(struct super_block *sb)
206{
207 struct fscrypt_keyring *keyring;
208
209 if (sb->s_master_keys)
210 return 0;
211
212 keyring = kzalloc(sizeof(*keyring), GFP_KERNEL);
213 if (!keyring)
214 return -ENOMEM;
215 spin_lock_init(&keyring->lock);
216 /*
217 * Pairs with the smp_load_acquire() in fscrypt_find_master_key().
218 * I.e., here we publish ->s_master_keys with a RELEASE barrier so that
219 * concurrent tasks can ACQUIRE it.
220 */
221 smp_store_release(&sb->s_master_keys, keyring);
222 return 0;
223}
224
225/*
226 * Release all encryption keys that have been added to the filesystem, along
227 * with the keyring that contains them.
228 *
229 * This is called at unmount time, after all potentially-encrypted inodes have
230 * been evicted. The filesystem's underlying block device(s) are still
231 * available at this time; this is important because after user file accesses
232 * have been allowed, this function may need to evict keys from the keyslots of
233 * an inline crypto engine, which requires the block device(s).
234 */
235void fscrypt_destroy_keyring(struct super_block *sb)
236{
237 struct fscrypt_keyring *keyring = sb->s_master_keys;
238 size_t i;
239
240 if (!keyring)
241 return;
242
243 for (i = 0; i < ARRAY_SIZE(keyring->key_hashtable); i++) {
244 struct hlist_head *bucket = &keyring->key_hashtable[i];
245 struct fscrypt_master_key *mk;
246 struct hlist_node *tmp;
247
248 hlist_for_each_entry_safe(mk, tmp, bucket, mk_node) {
249 /*
250 * Since all potentially-encrypted inodes were already
251 * evicted, every key remaining in the keyring should
252 * have an empty inode list, and should only still be in
253 * the keyring due to the single active ref associated
254 * with ->mk_present. There should be no structural
255 * refs beyond the one associated with the active ref.
256 */
257 WARN_ON_ONCE(refcount_read(&mk->mk_active_refs) != 1);
258 WARN_ON_ONCE(refcount_read(&mk->mk_struct_refs) != 1);
259 WARN_ON_ONCE(!mk->mk_present);
260 fscrypt_initiate_key_removal(sb, mk);
261 }
262 }
263 kfree_sensitive(objp: keyring);
264 sb->s_master_keys = NULL;
265}
266
267static struct hlist_head *
268fscrypt_mk_hash_bucket(struct fscrypt_keyring *keyring,
269 const struct fscrypt_key_specifier *mk_spec)
270{
271 /*
272 * Since key specifiers should be "random" values, it is sufficient to
273 * use a trivial hash function that just takes the first several bits of
274 * the key specifier.
275 */
276 unsigned long i = get_unaligned((unsigned long *)&mk_spec->u);
277
278 return &keyring->key_hashtable[i % ARRAY_SIZE(keyring->key_hashtable)];
279}
280
281/*
282 * Find the specified master key struct in ->s_master_keys and take a structural
283 * ref to it. The structural ref guarantees that the key struct continues to
284 * exist, but it does *not* guarantee that ->s_master_keys continues to contain
285 * the key struct. The structural ref needs to be dropped by
286 * fscrypt_put_master_key(). Returns NULL if the key struct is not found.
287 */
288struct fscrypt_master_key *
289fscrypt_find_master_key(struct super_block *sb,
290 const struct fscrypt_key_specifier *mk_spec)
291{
292 struct fscrypt_keyring *keyring;
293 struct hlist_head *bucket;
294 struct fscrypt_master_key *mk;
295
296 /*
297 * Pairs with the smp_store_release() in allocate_filesystem_keyring().
298 * I.e., another task can publish ->s_master_keys concurrently,
299 * executing a RELEASE barrier. We need to use smp_load_acquire() here
300 * to safely ACQUIRE the memory the other task published.
301 */
302 keyring = smp_load_acquire(&sb->s_master_keys);
303 if (keyring == NULL)
304 return NULL; /* No keyring yet, so no keys yet. */
305
306 bucket = fscrypt_mk_hash_bucket(keyring, mk_spec);
307 rcu_read_lock();
308 switch (mk_spec->type) {
309 case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
310 hlist_for_each_entry_rcu(mk, bucket, mk_node) {
311 if (mk->mk_spec.type ==
312 FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR &&
313 memcmp(p: mk->mk_spec.u.descriptor,
314 q: mk_spec->u.descriptor,
315 FSCRYPT_KEY_DESCRIPTOR_SIZE) == 0 &&
316 refcount_inc_not_zero(r: &mk->mk_struct_refs))
317 goto out;
318 }
319 break;
320 case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER:
321 hlist_for_each_entry_rcu(mk, bucket, mk_node) {
322 if (mk->mk_spec.type ==
323 FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER &&
324 memcmp(p: mk->mk_spec.u.identifier,
325 q: mk_spec->u.identifier,
326 FSCRYPT_KEY_IDENTIFIER_SIZE) == 0 &&
327 refcount_inc_not_zero(r: &mk->mk_struct_refs))
328 goto out;
329 }
330 break;
331 }
332 mk = NULL;
333out:
334 rcu_read_unlock();
335 return mk;
336}
337
338static int allocate_master_key_users_keyring(struct fscrypt_master_key *mk)
339{
340 char description[FSCRYPT_MK_USERS_DESCRIPTION_SIZE];
341 struct key *keyring;
342
343 format_mk_users_keyring_description(description,
344 mk_identifier: mk->mk_spec.u.identifier);
345 keyring = keyring_alloc(description, GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
346 current_cred(), KEY_POS_SEARCH |
347 KEY_USR_SEARCH | KEY_USR_READ | KEY_USR_VIEW,
348 KEY_ALLOC_NOT_IN_QUOTA, NULL, NULL);
349 if (IS_ERR(keyring))
350 return PTR_ERR(keyring);
351
352 mk->mk_users = keyring;
353 return 0;
354}
355
356/*
357 * Find the current user's "key" in the master key's ->mk_users.
358 * Returns ERR_PTR(-ENOKEY) if not found.
359 */
360static struct key *find_master_key_user(struct fscrypt_master_key *mk)
361{
362 char description[FSCRYPT_MK_USER_DESCRIPTION_SIZE];
363 key_ref_t keyref;
364
365 format_mk_user_description(description, mk_identifier: mk->mk_spec.u.identifier);
366
367 /*
368 * We need to mark the keyring reference as "possessed" so that we
369 * acquire permission to search it, via the KEY_POS_SEARCH permission.
370 */
371 keyref = keyring_search(keyring: make_key_ref(key: mk->mk_users, possession: true /*possessed*/),
372 type: &key_type_fscrypt_user, description, recurse: false);
373 if (IS_ERR(ptr: keyref)) {
374 if (PTR_ERR(ptr: keyref) == -EAGAIN || /* not found */
375 PTR_ERR(ptr: keyref) == -EKEYREVOKED) /* recently invalidated */
376 keyref = ERR_PTR(error: -ENOKEY);
377 return ERR_CAST(ptr: keyref);
378 }
379 return key_ref_to_ptr(key_ref: keyref);
380}
381
382/*
383 * Give the current user a "key" in ->mk_users. This charges the user's quota
384 * and marks the master key as added by the current user, so that it cannot be
385 * removed by another user with the key. Either ->mk_sem must be held for
386 * write, or the master key must be still undergoing initialization.
387 */
388static int add_master_key_user(struct fscrypt_master_key *mk)
389{
390 char description[FSCRYPT_MK_USER_DESCRIPTION_SIZE];
391 struct key *mk_user;
392 int err;
393
394 format_mk_user_description(description, mk_identifier: mk->mk_spec.u.identifier);
395 mk_user = key_alloc(type: &key_type_fscrypt_user, desc: description,
396 current_fsuid(), current_gid(), current_cred(),
397 KEY_POS_SEARCH | KEY_USR_VIEW, flags: 0, NULL);
398 if (IS_ERR(ptr: mk_user))
399 return PTR_ERR(ptr: mk_user);
400
401 err = key_instantiate_and_link(key: mk_user, NULL, datalen: 0, keyring: mk->mk_users, NULL);
402 key_put(key: mk_user);
403 return err;
404}
405
406/*
407 * Remove the current user's "key" from ->mk_users.
408 * ->mk_sem must be held for write.
409 *
410 * Returns 0 if removed, -ENOKEY if not found, or another -errno code.
411 */
412static int remove_master_key_user(struct fscrypt_master_key *mk)
413{
414 struct key *mk_user;
415 int err;
416
417 mk_user = find_master_key_user(mk);
418 if (IS_ERR(ptr: mk_user))
419 return PTR_ERR(ptr: mk_user);
420 err = key_unlink(keyring: mk->mk_users, key: mk_user);
421 key_put(key: mk_user);
422 return err;
423}
424
425/*
426 * Allocate a new fscrypt_master_key, transfer the given secret over to it, and
427 * insert it into sb->s_master_keys.
428 */
429static int add_new_master_key(struct super_block *sb,
430 struct fscrypt_master_key_secret *secret,
431 const struct fscrypt_key_specifier *mk_spec)
432{
433 struct fscrypt_keyring *keyring = sb->s_master_keys;
434 struct fscrypt_master_key *mk;
435 int err;
436
437 mk = kzalloc(sizeof(*mk), GFP_KERNEL);
438 if (!mk)
439 return -ENOMEM;
440
441 init_rwsem(&mk->mk_sem);
442 refcount_set(r: &mk->mk_struct_refs, n: 1);
443 mk->mk_spec = *mk_spec;
444
445 INIT_LIST_HEAD(list: &mk->mk_decrypted_inodes);
446 spin_lock_init(&mk->mk_decrypted_inodes_lock);
447
448 if (mk_spec->type == FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER) {
449 err = allocate_master_key_users_keyring(mk);
450 if (err)
451 goto out_put;
452 err = add_master_key_user(mk);
453 if (err)
454 goto out_put;
455 }
456
457 move_master_key_secret(dst: &mk->mk_secret, src: secret);
458 mk->mk_present = true;
459 refcount_set(r: &mk->mk_active_refs, n: 1); /* ->mk_present is true */
460
461 spin_lock(lock: &keyring->lock);
462 hlist_add_head_rcu(n: &mk->mk_node,
463 h: fscrypt_mk_hash_bucket(keyring, mk_spec));
464 spin_unlock(lock: &keyring->lock);
465 return 0;
466
467out_put:
468 fscrypt_put_master_key(mk);
469 return err;
470}
471
472#define KEY_DEAD 1
473
474static int add_existing_master_key(struct fscrypt_master_key *mk,
475 struct fscrypt_master_key_secret *secret)
476{
477 int err;
478
479 /*
480 * If the current user is already in ->mk_users, then there's nothing to
481 * do. Otherwise, we need to add the user to ->mk_users. (Neither is
482 * applicable for v1 policy keys, which have NULL ->mk_users.)
483 */
484 if (mk->mk_users) {
485 struct key *mk_user = find_master_key_user(mk);
486
487 if (mk_user != ERR_PTR(error: -ENOKEY)) {
488 if (IS_ERR(ptr: mk_user))
489 return PTR_ERR(ptr: mk_user);
490 key_put(key: mk_user);
491 return 0;
492 }
493 err = add_master_key_user(mk);
494 if (err)
495 return err;
496 }
497
498 /* If the key is incompletely removed, make it present again. */
499 if (!mk->mk_present) {
500 if (!refcount_inc_not_zero(r: &mk->mk_active_refs)) {
501 /*
502 * Raced with the last active ref being dropped, so the
503 * key has become, or is about to become, "absent".
504 * Therefore, we need to allocate a new key struct.
505 */
506 return KEY_DEAD;
507 }
508 move_master_key_secret(dst: &mk->mk_secret, src: secret);
509 WRITE_ONCE(mk->mk_present, true);
510 }
511
512 return 0;
513}
514
515static int do_add_master_key(struct super_block *sb,
516 struct fscrypt_master_key_secret *secret,
517 const struct fscrypt_key_specifier *mk_spec)
518{
519 static DEFINE_MUTEX(fscrypt_add_key_mutex);
520 struct fscrypt_master_key *mk;
521 int err;
522
523 mutex_lock(&fscrypt_add_key_mutex); /* serialize find + link */
524
525 mk = fscrypt_find_master_key(sb, mk_spec);
526 if (!mk) {
527 /* Didn't find the key in ->s_master_keys. Add it. */
528 err = allocate_filesystem_keyring(sb);
529 if (!err)
530 err = add_new_master_key(sb, secret, mk_spec);
531 } else {
532 /*
533 * Found the key in ->s_master_keys. Add the user to ->mk_users
534 * if needed, and make the key "present" again if possible.
535 */
536 down_write(sem: &mk->mk_sem);
537 err = add_existing_master_key(mk, secret);
538 up_write(sem: &mk->mk_sem);
539 if (err == KEY_DEAD) {
540 /*
541 * We found a key struct, but it's already been fully
542 * removed. Ignore the old struct and add a new one.
543 * fscrypt_add_key_mutex means we don't need to worry
544 * about concurrent adds.
545 */
546 err = add_new_master_key(sb, secret, mk_spec);
547 }
548 fscrypt_put_master_key(mk);
549 }
550 mutex_unlock(lock: &fscrypt_add_key_mutex);
551 return err;
552}
553
554static int add_master_key(struct super_block *sb,
555 struct fscrypt_master_key_secret *secret,
556 struct fscrypt_key_specifier *key_spec)
557{
558 int err;
559
560 if (key_spec->type == FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER) {
561 u8 sw_secret[BLK_CRYPTO_SW_SECRET_SIZE];
562 u8 *kdf_key = secret->bytes;
563 unsigned int kdf_key_size = secret->size;
564 u8 keyid_kdf_ctx = HKDF_CONTEXT_KEY_IDENTIFIER_FOR_RAW_KEY;
565
566 /*
567 * For raw keys, the fscrypt master key is used directly as the
568 * fscrypt KDF key. For hardware-wrapped keys, we have to pass
569 * the master key to the hardware to derive the KDF key, which
570 * is then only used to derive non-file-contents subkeys.
571 */
572 if (secret->is_hw_wrapped) {
573 err = fscrypt_derive_sw_secret(sb, wrapped_key: secret->bytes,
574 wrapped_key_size: secret->size, sw_secret);
575 if (err)
576 return err;
577 kdf_key = sw_secret;
578 kdf_key_size = sizeof(sw_secret);
579 /*
580 * To avoid weird behavior if someone manages to
581 * determine sw_secret and add it as a raw key, ensure
582 * that hardware-wrapped keys and raw keys will have
583 * different key identifiers by deriving their key
584 * identifiers using different KDF contexts.
585 */
586 keyid_kdf_ctx =
587 HKDF_CONTEXT_KEY_IDENTIFIER_FOR_HW_WRAPPED_KEY;
588 }
589 fscrypt_init_hkdf(hkdf: &secret->hkdf, master_key: kdf_key, master_key_size: kdf_key_size);
590 /*
591 * Now that the KDF context is initialized, the raw KDF key is
592 * no longer needed.
593 */
594 memzero_explicit(s: kdf_key, count: kdf_key_size);
595
596 /* Calculate the key identifier */
597 fscrypt_hkdf_expand(hkdf: &secret->hkdf, context: keyid_kdf_ctx, NULL, infolen: 0,
598 okm: key_spec->u.identifier,
599 FSCRYPT_KEY_IDENTIFIER_SIZE);
600 }
601 return do_add_master_key(sb, secret, mk_spec: key_spec);
602}
603
604/*
605 * Validate the size of an fscrypt master key being added. Note that this is
606 * just an initial check, as we don't know which ciphers will be used yet.
607 * There is a stricter size check later when the key is actually used by a file.
608 */
609static inline bool fscrypt_valid_key_size(size_t size, u32 add_key_flags)
610{
611 u32 max_size = (add_key_flags & FSCRYPT_ADD_KEY_FLAG_HW_WRAPPED) ?
612 FSCRYPT_MAX_HW_WRAPPED_KEY_SIZE :
613 FSCRYPT_MAX_RAW_KEY_SIZE;
614
615 return size >= FSCRYPT_MIN_KEY_SIZE && size <= max_size;
616}
617
618static int fscrypt_provisioning_key_preparse(struct key_preparsed_payload *prep)
619{
620 const struct fscrypt_provisioning_key_payload *payload = prep->data;
621
622 if (prep->datalen < sizeof(*payload))
623 return -EINVAL;
624
625 if (!fscrypt_valid_key_size(size: prep->datalen - sizeof(*payload),
626 add_key_flags: payload->flags))
627 return -EINVAL;
628
629 if (payload->type != FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR &&
630 payload->type != FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER)
631 return -EINVAL;
632
633 if (payload->flags & ~FSCRYPT_ADD_KEY_FLAG_HW_WRAPPED)
634 return -EINVAL;
635
636 prep->payload.data[0] = kmemdup(payload, prep->datalen, GFP_KERNEL);
637 if (!prep->payload.data[0])
638 return -ENOMEM;
639
640 prep->quotalen = prep->datalen;
641 return 0;
642}
643
644static void fscrypt_provisioning_key_free_preparse(
645 struct key_preparsed_payload *prep)
646{
647 kfree_sensitive(objp: prep->payload.data[0]);
648}
649
650static void fscrypt_provisioning_key_describe(const struct key *key,
651 struct seq_file *m)
652{
653 seq_puts(m, s: key->description);
654 if (key_is_positive(key)) {
655 const struct fscrypt_provisioning_key_payload *payload =
656 key->payload.data[0];
657
658 seq_printf(m, fmt: ": %u [%u]", key->datalen, payload->type);
659 }
660}
661
662static void fscrypt_provisioning_key_destroy(struct key *key)
663{
664 kfree_sensitive(objp: key->payload.data[0]);
665}
666
667static struct key_type key_type_fscrypt_provisioning = {
668 .name = "fscrypt-provisioning",
669 .preparse = fscrypt_provisioning_key_preparse,
670 .free_preparse = fscrypt_provisioning_key_free_preparse,
671 .instantiate = generic_key_instantiate,
672 .describe = fscrypt_provisioning_key_describe,
673 .destroy = fscrypt_provisioning_key_destroy,
674};
675
676/*
677 * Retrieve the key from the Linux keyring key specified by 'key_id', and store
678 * it into 'secret'.
679 *
680 * The key must be of type "fscrypt-provisioning" and must have the 'type' and
681 * 'flags' field of the payload set to the given values, indicating that the key
682 * is intended for use for the specified purpose. We don't use the "logon" key
683 * type because there's no way to completely restrict the use of such keys; they
684 * can be used by any kernel API that accepts "logon" keys and doesn't require a
685 * specific service prefix.
686 *
687 * The ability to specify the key via Linux keyring key is intended for cases
688 * where userspace needs to re-add keys after the filesystem is unmounted and
689 * re-mounted. Most users should just provide the key directly instead.
690 */
691static int get_keyring_key(u32 key_id, u32 type, u32 flags,
692 struct fscrypt_master_key_secret *secret)
693{
694 key_ref_t ref;
695 struct key *key;
696 const struct fscrypt_provisioning_key_payload *payload;
697 int err;
698
699 ref = lookup_user_key(id: key_id, flags: 0, need_perm: KEY_NEED_SEARCH);
700 if (IS_ERR(ptr: ref))
701 return PTR_ERR(ptr: ref);
702 key = key_ref_to_ptr(key_ref: ref);
703
704 if (key->type != &key_type_fscrypt_provisioning)
705 goto bad_key;
706 payload = key->payload.data[0];
707
708 /*
709 * Don't allow fscrypt v1 keys to be used as v2 keys and vice versa.
710 * Similarly, don't allow hardware-wrapped keys to be used as
711 * non-hardware-wrapped keys and vice versa.
712 */
713 if (payload->type != type || payload->flags != flags)
714 goto bad_key;
715
716 secret->size = key->datalen - sizeof(*payload);
717 memcpy(secret->bytes, payload->raw, secret->size);
718 err = 0;
719 goto out_put;
720
721bad_key:
722 err = -EKEYREJECTED;
723out_put:
724 key_ref_put(key_ref: ref);
725 return err;
726}
727
728/*
729 * Add a master encryption key to the filesystem, causing all files which were
730 * encrypted with it to appear "unlocked" (decrypted) when accessed.
731 *
732 * When adding a key for use by v1 encryption policies, this ioctl is
733 * privileged, and userspace must provide the 'key_descriptor'.
734 *
735 * When adding a key for use by v2+ encryption policies, this ioctl is
736 * unprivileged. This is needed, in general, to allow non-root users to use
737 * encryption without encountering the visibility problems of process-subscribed
738 * keyrings and the inability to properly remove keys. This works by having
739 * each key identified by its cryptographically secure hash --- the
740 * 'key_identifier'. The cryptographic hash ensures that a malicious user
741 * cannot add the wrong key for a given identifier. Furthermore, each added key
742 * is charged to the appropriate user's quota for the keyrings service, which
743 * prevents a malicious user from adding too many keys. Finally, we forbid a
744 * user from removing a key while other users have added it too, which prevents
745 * a user who knows another user's key from causing a denial-of-service by
746 * removing it at an inopportune time. (We tolerate that a user who knows a key
747 * can prevent other users from removing it.)
748 *
749 * For more details, see the "FS_IOC_ADD_ENCRYPTION_KEY" section of
750 * Documentation/filesystems/fscrypt.rst.
751 */
752int fscrypt_ioctl_add_key(struct file *filp, void __user *_uarg)
753{
754 struct super_block *sb = file_inode(f: filp)->i_sb;
755 struct fscrypt_add_key_arg __user *uarg = _uarg;
756 struct fscrypt_add_key_arg arg;
757 struct fscrypt_master_key_secret secret;
758 int err;
759
760 if (copy_from_user(to: &arg, from: uarg, n: sizeof(arg)))
761 return -EFAULT;
762
763 if (!valid_key_spec(spec: &arg.key_spec))
764 return -EINVAL;
765
766 if (memchr_inv(p: arg.__reserved, c: 0, size: sizeof(arg.__reserved)))
767 return -EINVAL;
768
769 /*
770 * Only root can add keys that are identified by an arbitrary descriptor
771 * rather than by a cryptographic hash --- since otherwise a malicious
772 * user could add the wrong key.
773 */
774 if (arg.key_spec.type == FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR &&
775 !capable(CAP_SYS_ADMIN))
776 return -EACCES;
777
778 memset(&secret, 0, sizeof(secret));
779
780 if (arg.flags) {
781 if (arg.flags & ~FSCRYPT_ADD_KEY_FLAG_HW_WRAPPED)
782 return -EINVAL;
783 if (arg.key_spec.type != FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER)
784 return -EINVAL;
785 secret.is_hw_wrapped = true;
786 }
787
788 if (arg.key_id) {
789 if (arg.raw_size != 0)
790 return -EINVAL;
791 err = get_keyring_key(key_id: arg.key_id, type: arg.key_spec.type, flags: arg.flags,
792 secret: &secret);
793 if (err)
794 goto out_wipe_secret;
795 } else {
796 if (!fscrypt_valid_key_size(size: arg.raw_size, add_key_flags: arg.flags))
797 return -EINVAL;
798 secret.size = arg.raw_size;
799 err = -EFAULT;
800 if (copy_from_user(to: secret.bytes, from: uarg->raw, n: secret.size))
801 goto out_wipe_secret;
802 }
803
804 err = add_master_key(sb, secret: &secret, key_spec: &arg.key_spec);
805 if (err)
806 goto out_wipe_secret;
807
808 /* Return the key identifier to userspace, if applicable */
809 err = -EFAULT;
810 if (arg.key_spec.type == FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER &&
811 copy_to_user(to: uarg->key_spec.u.identifier, from: arg.key_spec.u.identifier,
812 FSCRYPT_KEY_IDENTIFIER_SIZE))
813 goto out_wipe_secret;
814 err = 0;
815out_wipe_secret:
816 wipe_master_key_secret(secret: &secret);
817 return err;
818}
819EXPORT_SYMBOL_GPL(fscrypt_ioctl_add_key);
820
821static void
822fscrypt_get_test_dummy_secret(struct fscrypt_master_key_secret *secret)
823{
824 static u8 test_key[FSCRYPT_MAX_RAW_KEY_SIZE];
825
826 get_random_once(test_key, sizeof(test_key));
827
828 memset(secret, 0, sizeof(*secret));
829 secret->size = sizeof(test_key);
830 memcpy(secret->bytes, test_key, sizeof(test_key));
831}
832
833void fscrypt_get_test_dummy_key_identifier(
834 u8 key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE])
835{
836 struct fscrypt_master_key_secret secret;
837
838 fscrypt_get_test_dummy_secret(secret: &secret);
839 fscrypt_init_hkdf(hkdf: &secret.hkdf, master_key: secret.bytes, master_key_size: secret.size);
840 fscrypt_hkdf_expand(hkdf: &secret.hkdf,
841 HKDF_CONTEXT_KEY_IDENTIFIER_FOR_RAW_KEY, NULL, infolen: 0,
842 okm: key_identifier, FSCRYPT_KEY_IDENTIFIER_SIZE);
843 wipe_master_key_secret(secret: &secret);
844}
845
846/**
847 * fscrypt_add_test_dummy_key() - add the test dummy encryption key
848 * @sb: the filesystem instance to add the key to
849 * @key_spec: the key specifier of the test dummy encryption key
850 *
851 * Add the key for the test_dummy_encryption mount option to the filesystem. To
852 * prevent misuse of this mount option, a per-boot random key is used instead of
853 * a hardcoded one. This makes it so that any encrypted files created using
854 * this option won't be accessible after a reboot.
855 *
856 * Return: 0 on success, -errno on failure
857 */
858int fscrypt_add_test_dummy_key(struct super_block *sb,
859 struct fscrypt_key_specifier *key_spec)
860{
861 struct fscrypt_master_key_secret secret;
862 int err;
863
864 fscrypt_get_test_dummy_secret(secret: &secret);
865 err = add_master_key(sb, secret: &secret, key_spec);
866 wipe_master_key_secret(secret: &secret);
867 return err;
868}
869
870/*
871 * Verify that the current user has added a master key with the given identifier
872 * (returns -ENOKEY if not). This is needed to prevent a user from encrypting
873 * their files using some other user's key which they don't actually know.
874 * Cryptographically this isn't much of a problem, but the semantics of this
875 * would be a bit weird, so it's best to just forbid it.
876 *
877 * The system administrator (CAP_FOWNER) can override this, which should be
878 * enough for any use cases where encryption policies are being set using keys
879 * that were chosen ahead of time but aren't available at the moment.
880 *
881 * Note that the key may have already removed by the time this returns, but
882 * that's okay; we just care whether the key was there at some point.
883 *
884 * Return: 0 if the key is added, -ENOKEY if it isn't, or another -errno code
885 */
886int fscrypt_verify_key_added(struct super_block *sb,
887 const u8 identifier[FSCRYPT_KEY_IDENTIFIER_SIZE])
888{
889 struct fscrypt_key_specifier mk_spec;
890 struct fscrypt_master_key *mk;
891 struct key *mk_user;
892 int err;
893
894 mk_spec.type = FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER;
895 memcpy(mk_spec.u.identifier, identifier, FSCRYPT_KEY_IDENTIFIER_SIZE);
896
897 mk = fscrypt_find_master_key(sb, mk_spec: &mk_spec);
898 if (!mk) {
899 err = -ENOKEY;
900 goto out;
901 }
902 down_read(sem: &mk->mk_sem);
903 mk_user = find_master_key_user(mk);
904 if (IS_ERR(ptr: mk_user)) {
905 err = PTR_ERR(ptr: mk_user);
906 } else {
907 key_put(key: mk_user);
908 err = 0;
909 }
910 up_read(sem: &mk->mk_sem);
911 fscrypt_put_master_key(mk);
912out:
913 if (err == -ENOKEY && capable(CAP_FOWNER))
914 err = 0;
915 return err;
916}
917
918/*
919 * Try to evict the inode's dentries from the dentry cache. If the inode is a
920 * directory, then it can have at most one dentry; however, that dentry may be
921 * pinned by child dentries, so first try to evict the children too.
922 */
923static void shrink_dcache_inode(struct inode *inode)
924{
925 struct dentry *dentry;
926
927 if (S_ISDIR(inode->i_mode)) {
928 dentry = d_find_any_alias(inode);
929 if (dentry) {
930 shrink_dcache_parent(dentry);
931 dput(dentry);
932 }
933 }
934 d_prune_aliases(inode);
935}
936
937static void evict_dentries_for_decrypted_inodes(struct fscrypt_master_key *mk)
938{
939 struct fscrypt_inode_info *ci;
940 struct inode *inode;
941 struct inode *toput_inode = NULL;
942
943 spin_lock(lock: &mk->mk_decrypted_inodes_lock);
944
945 list_for_each_entry(ci, &mk->mk_decrypted_inodes, ci_master_key_link) {
946 inode = ci->ci_inode;
947 spin_lock(lock: &inode->i_lock);
948 if (inode_state_read(inode) & (I_FREEING | I_WILL_FREE | I_NEW)) {
949 spin_unlock(lock: &inode->i_lock);
950 continue;
951 }
952 __iget(inode);
953 spin_unlock(lock: &inode->i_lock);
954 spin_unlock(lock: &mk->mk_decrypted_inodes_lock);
955
956 shrink_dcache_inode(inode);
957 iput(toput_inode);
958 toput_inode = inode;
959
960 spin_lock(lock: &mk->mk_decrypted_inodes_lock);
961 }
962
963 spin_unlock(lock: &mk->mk_decrypted_inodes_lock);
964 iput(toput_inode);
965}
966
967static int check_for_busy_inodes(struct super_block *sb,
968 struct fscrypt_master_key *mk)
969{
970 struct list_head *pos;
971 size_t busy_count = 0;
972 unsigned long ino;
973 char ino_str[50] = "";
974
975 spin_lock(lock: &mk->mk_decrypted_inodes_lock);
976
977 list_for_each(pos, &mk->mk_decrypted_inodes)
978 busy_count++;
979
980 if (busy_count == 0) {
981 spin_unlock(lock: &mk->mk_decrypted_inodes_lock);
982 return 0;
983 }
984
985 {
986 /* select an example file to show for debugging purposes */
987 struct inode *inode =
988 list_first_entry(&mk->mk_decrypted_inodes,
989 struct fscrypt_inode_info,
990 ci_master_key_link)->ci_inode;
991 ino = inode->i_ino;
992 }
993 spin_unlock(lock: &mk->mk_decrypted_inodes_lock);
994
995 /* If the inode is currently being created, ino may still be 0. */
996 if (ino)
997 snprintf(buf: ino_str, size: sizeof(ino_str), fmt: ", including ino %lu", ino);
998
999 fscrypt_warn(NULL,
1000 "%s: %zu inode(s) still busy after removing key with %s %*phN%s",
1001 sb->s_id, busy_count, master_key_spec_type(&mk->mk_spec),
1002 master_key_spec_len(&mk->mk_spec), (u8 *)&mk->mk_spec.u,
1003 ino_str);
1004 return -EBUSY;
1005}
1006
1007static int try_to_lock_encrypted_files(struct super_block *sb,
1008 struct fscrypt_master_key *mk)
1009{
1010 int err1;
1011 int err2;
1012
1013 /*
1014 * An inode can't be evicted while it is dirty or has dirty pages.
1015 * Thus, we first have to clean the inodes in ->mk_decrypted_inodes.
1016 *
1017 * Just do it the easy way: call sync_filesystem(). It's overkill, but
1018 * it works, and it's more important to minimize the amount of caches we
1019 * drop than the amount of data we sync. Also, unprivileged users can
1020 * already call sync_filesystem() via sys_syncfs() or sys_sync().
1021 */
1022 down_read(sem: &sb->s_umount);
1023 err1 = sync_filesystem(sb);
1024 up_read(sem: &sb->s_umount);
1025 /* If a sync error occurs, still try to evict as much as possible. */
1026
1027 /*
1028 * Inodes are pinned by their dentries, so we have to evict their
1029 * dentries. shrink_dcache_sb() would suffice, but would be overkill
1030 * and inappropriate for use by unprivileged users. So instead go
1031 * through the inodes' alias lists and try to evict each dentry.
1032 */
1033 evict_dentries_for_decrypted_inodes(mk);
1034
1035 /*
1036 * evict_dentries_for_decrypted_inodes() already iput() each inode in
1037 * the list; any inodes for which that dropped the last reference will
1038 * have been evicted due to fscrypt_drop_inode() detecting the key
1039 * removal and telling the VFS to evict the inode. So to finish, we
1040 * just need to check whether any inodes couldn't be evicted.
1041 */
1042 err2 = check_for_busy_inodes(sb, mk);
1043
1044 return err1 ?: err2;
1045}
1046
1047/*
1048 * Try to remove an fscrypt master encryption key.
1049 *
1050 * FS_IOC_REMOVE_ENCRYPTION_KEY (all_users=false) removes the current user's
1051 * claim to the key, then removes the key itself if no other users have claims.
1052 * FS_IOC_REMOVE_ENCRYPTION_KEY_ALL_USERS (all_users=true) always removes the
1053 * key itself.
1054 *
1055 * To "remove the key itself", first we transition the key to the "incompletely
1056 * removed" state, so that no more inodes can be unlocked with it. Then we try
1057 * to evict all cached inodes that had been unlocked with the key.
1058 *
1059 * If all inodes were evicted, then we unlink the fscrypt_master_key from the
1060 * keyring. Otherwise it remains in the keyring in the "incompletely removed"
1061 * state where it tracks the list of remaining inodes. Userspace can execute
1062 * the ioctl again later to retry eviction, or alternatively can re-add the key.
1063 *
1064 * For more details, see the "Removing keys" section of
1065 * Documentation/filesystems/fscrypt.rst.
1066 */
1067static int do_remove_key(struct file *filp, void __user *_uarg, bool all_users)
1068{
1069 struct super_block *sb = file_inode(f: filp)->i_sb;
1070 struct fscrypt_remove_key_arg __user *uarg = _uarg;
1071 struct fscrypt_remove_key_arg arg;
1072 struct fscrypt_master_key *mk;
1073 u32 status_flags = 0;
1074 int err;
1075 bool inodes_remain;
1076
1077 if (copy_from_user(to: &arg, from: uarg, n: sizeof(arg)))
1078 return -EFAULT;
1079
1080 if (!valid_key_spec(spec: &arg.key_spec))
1081 return -EINVAL;
1082
1083 if (memchr_inv(p: arg.__reserved, c: 0, size: sizeof(arg.__reserved)))
1084 return -EINVAL;
1085
1086 /*
1087 * Only root can add and remove keys that are identified by an arbitrary
1088 * descriptor rather than by a cryptographic hash.
1089 */
1090 if (arg.key_spec.type == FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR &&
1091 !capable(CAP_SYS_ADMIN))
1092 return -EACCES;
1093
1094 /* Find the key being removed. */
1095 mk = fscrypt_find_master_key(sb, mk_spec: &arg.key_spec);
1096 if (!mk)
1097 return -ENOKEY;
1098 down_write(sem: &mk->mk_sem);
1099
1100 /* If relevant, remove current user's (or all users) claim to the key */
1101 if (mk->mk_users && mk->mk_users->keys.nr_leaves_on_tree != 0) {
1102 if (all_users)
1103 err = keyring_clear(keyring: mk->mk_users);
1104 else
1105 err = remove_master_key_user(mk);
1106 if (err) {
1107 up_write(sem: &mk->mk_sem);
1108 goto out_put_key;
1109 }
1110 if (mk->mk_users->keys.nr_leaves_on_tree != 0) {
1111 /*
1112 * Other users have still added the key too. We removed
1113 * the current user's claim to the key, but we still
1114 * can't remove the key itself.
1115 */
1116 status_flags |=
1117 FSCRYPT_KEY_REMOVAL_STATUS_FLAG_OTHER_USERS;
1118 err = 0;
1119 up_write(sem: &mk->mk_sem);
1120 goto out_put_key;
1121 }
1122 }
1123
1124 /* No user claims remaining. Initiate removal of the key. */
1125 err = -ENOKEY;
1126 if (mk->mk_present) {
1127 fscrypt_initiate_key_removal(sb, mk);
1128 err = 0;
1129 }
1130 inodes_remain = refcount_read(r: &mk->mk_active_refs) > 0;
1131 up_write(sem: &mk->mk_sem);
1132
1133 if (inodes_remain) {
1134 /* Some inodes still reference this key; try to evict them. */
1135 err = try_to_lock_encrypted_files(sb, mk);
1136 if (err == -EBUSY) {
1137 status_flags |=
1138 FSCRYPT_KEY_REMOVAL_STATUS_FLAG_FILES_BUSY;
1139 err = 0;
1140 }
1141 }
1142 /*
1143 * We return 0 if we successfully did something: removed a claim to the
1144 * key, initiated removal of the key, or tried locking the files again.
1145 * Users need to check the informational status flags if they care
1146 * whether the key has been fully removed including all files locked.
1147 */
1148out_put_key:
1149 fscrypt_put_master_key(mk);
1150 if (err == 0)
1151 err = put_user(status_flags, &uarg->removal_status_flags);
1152 return err;
1153}
1154
1155int fscrypt_ioctl_remove_key(struct file *filp, void __user *uarg)
1156{
1157 return do_remove_key(filp, uarg: uarg, all_users: false);
1158}
1159EXPORT_SYMBOL_GPL(fscrypt_ioctl_remove_key);
1160
1161int fscrypt_ioctl_remove_key_all_users(struct file *filp, void __user *uarg)
1162{
1163 if (!capable(CAP_SYS_ADMIN))
1164 return -EACCES;
1165 return do_remove_key(filp, uarg: uarg, all_users: true);
1166}
1167EXPORT_SYMBOL_GPL(fscrypt_ioctl_remove_key_all_users);
1168
1169/*
1170 * Retrieve the status of an fscrypt master encryption key.
1171 *
1172 * We set ->status to indicate whether the key is absent, present, or
1173 * incompletely removed. (For an explanation of what these statuses mean and
1174 * how they are represented internally, see struct fscrypt_master_key.) This
1175 * field allows applications to easily determine the status of an encrypted
1176 * directory without using a hack such as trying to open a regular file in it
1177 * (which can confuse the "incompletely removed" status with absent or present).
1178 *
1179 * In addition, for v2 policy keys we allow applications to determine, via
1180 * ->status_flags and ->user_count, whether the key has been added by the
1181 * current user, by other users, or by both. Most applications should not need
1182 * this, since ordinarily only one user should know a given key. However, if a
1183 * secret key is shared by multiple users, applications may wish to add an
1184 * already-present key to prevent other users from removing it. This ioctl can
1185 * be used to check whether that really is the case before the work is done to
1186 * add the key --- which might e.g. require prompting the user for a passphrase.
1187 *
1188 * For more details, see the "FS_IOC_GET_ENCRYPTION_KEY_STATUS" section of
1189 * Documentation/filesystems/fscrypt.rst.
1190 */
1191int fscrypt_ioctl_get_key_status(struct file *filp, void __user *uarg)
1192{
1193 struct super_block *sb = file_inode(f: filp)->i_sb;
1194 struct fscrypt_get_key_status_arg arg;
1195 struct fscrypt_master_key *mk;
1196 int err;
1197
1198 if (copy_from_user(to: &arg, from: uarg, n: sizeof(arg)))
1199 return -EFAULT;
1200
1201 if (!valid_key_spec(spec: &arg.key_spec))
1202 return -EINVAL;
1203
1204 if (memchr_inv(p: arg.__reserved, c: 0, size: sizeof(arg.__reserved)))
1205 return -EINVAL;
1206
1207 arg.status_flags = 0;
1208 arg.user_count = 0;
1209 memset(arg.__out_reserved, 0, sizeof(arg.__out_reserved));
1210
1211 mk = fscrypt_find_master_key(sb, mk_spec: &arg.key_spec);
1212 if (!mk) {
1213 arg.status = FSCRYPT_KEY_STATUS_ABSENT;
1214 err = 0;
1215 goto out;
1216 }
1217 down_read(sem: &mk->mk_sem);
1218
1219 if (!mk->mk_present) {
1220 arg.status = refcount_read(r: &mk->mk_active_refs) > 0 ?
1221 FSCRYPT_KEY_STATUS_INCOMPLETELY_REMOVED :
1222 FSCRYPT_KEY_STATUS_ABSENT /* raced with full removal */;
1223 err = 0;
1224 goto out_release_key;
1225 }
1226
1227 arg.status = FSCRYPT_KEY_STATUS_PRESENT;
1228 if (mk->mk_users) {
1229 struct key *mk_user;
1230
1231 arg.user_count = mk->mk_users->keys.nr_leaves_on_tree;
1232 mk_user = find_master_key_user(mk);
1233 if (!IS_ERR(ptr: mk_user)) {
1234 arg.status_flags |=
1235 FSCRYPT_KEY_STATUS_FLAG_ADDED_BY_SELF;
1236 key_put(key: mk_user);
1237 } else if (mk_user != ERR_PTR(error: -ENOKEY)) {
1238 err = PTR_ERR(ptr: mk_user);
1239 goto out_release_key;
1240 }
1241 }
1242 err = 0;
1243out_release_key:
1244 up_read(sem: &mk->mk_sem);
1245 fscrypt_put_master_key(mk);
1246out:
1247 if (!err && copy_to_user(to: uarg, from: &arg, n: sizeof(arg)))
1248 err = -EFAULT;
1249 return err;
1250}
1251EXPORT_SYMBOL_GPL(fscrypt_ioctl_get_key_status);
1252
1253int __init fscrypt_init_keyring(void)
1254{
1255 int err;
1256
1257 err = register_key_type(ktype: &key_type_fscrypt_user);
1258 if (err)
1259 return err;
1260
1261 err = register_key_type(ktype: &key_type_fscrypt_provisioning);
1262 if (err)
1263 goto err_unregister_fscrypt_user;
1264
1265 return 0;
1266
1267err_unregister_fscrypt_user:
1268 unregister_key_type(ktype: &key_type_fscrypt_user);
1269 return err;
1270}
1271

source code of linux/fs/crypto/keyring.c