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2024-02-20 ea08eeccae9297f7aabd2ef7f0c2517ac4549acc 
 kernel/fs/crypto/fscrypt_private.h
....@@ -14,17 +14,21 @@
1414 #include <linux/fscrypt.h>
1515 #include <linux/siphash.h>
1616 #include <crypto/hash.h>
17
-#include <linux/bio-crypt-ctx.h>
17
+#include <linux/blk-crypto.h>
1818 
1919 #define CONST_STRLEN(str)	(sizeof(str) - 1)
2020 
21
-#define FS_KEY_DERIVATION_NONCE_SIZE	16
21
+#define FSCRYPT_FILE_NONCE_SIZE	16
2222 
23
-#define FSCRYPT_MIN_KEY_SIZE		16
23
+#define FSCRYPT_MIN_KEY_SIZE	16
24
+
2425 #define FSCRYPT_MAX_HW_WRAPPED_KEY_SIZE	128
2526 
2627 #define FSCRYPT_CONTEXT_V1	1
2728 #define FSCRYPT_CONTEXT_V2	2
29
+
30
+/* Keep this in sync with include/uapi/linux/fscrypt.h */
31
+#define FSCRYPT_MODE_MAX	FSCRYPT_MODE_ADIANTUM
2832 
2933 struct fscrypt_context_v1 {
3034 	u8 version; /* FSCRYPT_CONTEXT_V1 */
....@@ -32,7 +36,7 @@
3236 	u8 filenames_encryption_mode;
3337 	u8 flags;
3438 	u8 master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
35
-	u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
39
+	u8 nonce[FSCRYPT_FILE_NONCE_SIZE];
3640 };
3741 
3842 struct fscrypt_context_v2 {
....@@ -42,7 +46,7 @@
4246 	u8 flags;
4347 	u8 __reserved[4];
4448 	u8 master_key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE];
45
-	u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
49
+	u8 nonce[FSCRYPT_FILE_NONCE_SIZE];
4650 };
4751 
4852 /*
....@@ -98,7 +102,6 @@
98102 	return NULL;
99103 }
100104 
101
-#undef fscrypt_policy
102105 union fscrypt_policy {
103106 	u8 version;
104107 	struct fscrypt_policy_v1 v1;
....@@ -192,9 +195,9 @@
192195 struct fscrypt_info {
193196 
194197 	/* The key in a form prepared for actual encryption/decryption */
195
-	struct fscrypt_prepared_key	ci_key;
198
+	struct fscrypt_prepared_key ci_enc_key;
196199 
197
-	/* True if the key should be freed when this fscrypt_info is freed */
200
+	/* True if ci_enc_key should be freed when this fscrypt_info is freed */
198201 	bool ci_owns_key;
199202 
200203 #ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT
....@@ -219,7 +222,16 @@
219222 	 * will be NULL if the master key was found in a process-subscribed
220223 	 * keyring rather than in the filesystem-level keyring.
221224 	 */
225
+#ifdef __GENKSYMS__
226
+	/*
227
+	 * Android ABI CRC preservation due to commit 391cceee6d43 ("fscrypt:
228
+	 * stop using keyrings subsystem for fscrypt_master_key") changing this
229
+	 * type.  Size is the same, this is a private field.
230
+	 */
222231 	struct key *ci_master_key;
232
+#else
233
+	struct fscrypt_master_key *ci_master_key;
234
+#endif
223235 
224236 	/*
225237 	 * Link in list of inodes that were unlocked with the master key.
....@@ -229,7 +241,7 @@
229241 
230242 	/*
231243 	 * If non-NULL, then encryption is done using the master key directly
232
-	 * and ci_key will equal ci_direct_key->dk_key.
244
+	 * and ci_enc_key will equal ci_direct_key->dk_key.
233245 	 */
234246 	struct fscrypt_direct_key *ci_direct_key;
235247 
....@@ -245,7 +257,7 @@
245257 	union fscrypt_policy ci_policy;
246258 
247259 	/* This inode's nonce, copied from the fscrypt_context */
248
-	u8 ci_nonce[FS_KEY_DERIVATION_NONCE_SIZE];
260
+	u8 ci_nonce[FSCRYPT_FILE_NONCE_SIZE];
249261 
250262 	/* Hashed inode number.  Only set for IV_INO_LBLK_32 */
251263 	u32 ci_hashed_ino;
....@@ -281,7 +293,7 @@
281293 		__le64 lblk_num;
282294 
283295 		/* per-file nonce; only set in DIRECT_KEY mode */
284
-		u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
296
+		u8 nonce[FSCRYPT_FILE_NONCE_SIZE];
285297 	};
286298 	u8 raw[FSCRYPT_MAX_IV_SIZE];
287299 	__le64 dun[FSCRYPT_MAX_IV_SIZE / sizeof(__le64)];
....@@ -293,8 +305,9 @@
293305 /* fname.c */
294306 int fscrypt_fname_encrypt(const struct inode *inode, const struct qstr *iname,
295307 			  u8 *out, unsigned int olen);
296
-bool fscrypt_fname_encrypted_size(const struct inode *inode, u32 orig_len,
297
-				  u32 max_len, u32 *encrypted_len_ret);
308
+bool fscrypt_fname_encrypted_size(const union fscrypt_policy *policy,
309
+				  u32 orig_len, u32 max_len,
310
+				  u32 *encrypted_len_ret);
298311 
299312 /* hkdf.c */
300313 
....@@ -312,13 +325,13 @@
312325  * outputs are unique and cryptographically isolated, i.e. knowledge of one
313326  * output doesn't reveal another.
314327  */
315
-#define HKDF_CONTEXT_KEY_IDENTIFIER	1
316
-#define HKDF_CONTEXT_PER_FILE_ENC_KEY	2
317
-#define HKDF_CONTEXT_DIRECT_KEY		3
318
-#define HKDF_CONTEXT_IV_INO_LBLK_64_KEY	4
319
-#define HKDF_CONTEXT_DIRHASH_KEY	5
320
-#define HKDF_CONTEXT_IV_INO_LBLK_32_KEY	6
321
-#define HKDF_CONTEXT_INODE_HASH_KEY	7
328
+#define HKDF_CONTEXT_KEY_IDENTIFIER	1 /* info=<empty>		*/
329
+#define HKDF_CONTEXT_PER_FILE_ENC_KEY	2 /* info=file_nonce		*/
330
+#define HKDF_CONTEXT_DIRECT_KEY		3 /* info=mode_num		*/
331
+#define HKDF_CONTEXT_IV_INO_LBLK_64_KEY	4 /* info=mode_num||fs_uuid	*/
332
+#define HKDF_CONTEXT_DIRHASH_KEY	5 /* info=file_nonce		*/
333
+#define HKDF_CONTEXT_IV_INO_LBLK_32_KEY	6 /* info=mode_num||fs_uuid	*/
334
+#define HKDF_CONTEXT_INODE_HASH_KEY	7 /* info=<empty>		*/
322335 
323336 int fscrypt_hkdf_expand(const struct fscrypt_hkdf *hkdf, u8 context,
324337 			const u8 *info, unsigned int infolen,
....@@ -328,8 +341,8 @@
328341 
329342 /* inline_crypt.c */
330343 #ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT
331
-extern int fscrypt_select_encryption_impl(struct fscrypt_info *ci,
332
-					  bool is_hw_wrapped_key);
344
+int fscrypt_select_encryption_impl(struct fscrypt_info *ci,
345
+				   bool is_hw_wrapped_key);
333346 
334347 static inline bool
335348 fscrypt_using_inline_encryption(const struct fscrypt_info *ci)
....@@ -337,15 +350,13 @@
337350 	return ci->ci_inlinecrypt;
338351 }
339352 
340
-extern int fscrypt_prepare_inline_crypt_key(
341
-					struct fscrypt_prepared_key *prep_key,
342
-					const u8 *raw_key,
343
-					unsigned int raw_key_size,
344
-					bool is_hw_wrapped,
345
-					const struct fscrypt_info *ci);
353
+int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key,
354
+				     const u8 *raw_key,
355
+				     unsigned int raw_key_size,
356
+				     bool is_hw_wrapped,
357
+				     const struct fscrypt_info *ci);
346358 
347
-extern void fscrypt_destroy_inline_crypt_key(
348
-					struct fscrypt_prepared_key *prep_key);
359
+void fscrypt_destroy_inline_crypt_key(struct fscrypt_prepared_key *prep_key);
349360 
350361 extern int fscrypt_derive_raw_secret(struct super_block *sb,
351362 				     const u8 *wrapped_key,
....@@ -382,8 +393,8 @@
382393 	return 0;
383394 }
384395 
385
-static inline bool fscrypt_using_inline_encryption(
386
-					const struct fscrypt_info *ci)
396
+static inline bool
397
+fscrypt_using_inline_encryption(const struct fscrypt_info *ci)
387398 {
388399 	return false;
389400 }
....@@ -460,6 +471,40 @@
460471 struct fscrypt_master_key {
461472 
462473 	/*
474
+	 * Back-pointer to the super_block of the filesystem to which this
475
+	 * master key has been added.  Only valid if ->mk_active_refs > 0.
476
+	 */
477
+	struct super_block			*mk_sb;
478
+
479
+	/*
480
+	 * Link in ->mk_sb->s_master_keys->key_hashtable.
481
+	 * Only valid if ->mk_active_refs > 0.
482
+	 */
483
+	struct hlist_node			mk_node;
484
+
485
+	/* Semaphore that protects ->mk_secret and ->mk_users */
486
+	struct rw_semaphore			mk_sem;
487
+
488
+	/*
489
+	 * Active and structural reference counts.  An active ref guarantees
490
+	 * that the struct continues to exist, continues to be in the keyring
491
+	 * ->mk_sb->s_master_keys, and that any embedded subkeys (e.g.
492
+	 * ->mk_direct_keys) that have been prepared continue to exist.
493
+	 * A structural ref only guarantees that the struct continues to exist.
494
+	 *
495
+	 * There is one active ref associated with ->mk_secret being present,
496
+	 * and one active ref for each inode in ->mk_decrypted_inodes.
497
+	 *
498
+	 * There is one structural ref associated with the active refcount being
499
+	 * nonzero.  Finding a key in the keyring also takes a structural ref,
500
+	 * which is then held temporarily while the key is operated on.
501
+	 */
502
+	refcount_t				mk_active_refs;
503
+	refcount_t				mk_struct_refs;
504
+
505
+	struct rcu_head				mk_rcu_head;
506
+
507
+	/*
463508 	 * The secret key material.  After FS_IOC_REMOVE_ENCRYPTION_KEY is
464509 	 * executed, this is wiped and no new inodes can be unlocked with this
465510 	 * key; however, there may still be inodes in ->mk_decrypted_inodes
....@@ -467,16 +512,12 @@
467512 	 * FS_IOC_REMOVE_ENCRYPTION_KEY can be retried, or
468513 	 * FS_IOC_ADD_ENCRYPTION_KEY can add the secret again.
469514 	 *
470
-	 * Locking: protected by key->sem (outer) and mk_secret_sem (inner).
471
-	 * The reason for two locks is that key->sem also protects modifying
472
-	 * mk_users, which ranks it above the semaphore for the keyring key
473
-	 * type, which is in turn above page faults (via keyring_read).  But
474
-	 * sometimes filesystems call fscrypt_get_encryption_info() from within
475
-	 * a transaction, which ranks it below page faults.  So we need a
476
-	 * separate lock which protects mk_secret but not also mk_users.
515
+	 * While ->mk_secret is present, one ref in ->mk_active_refs is held.
516
+	 *
517
+	 * Locking: protected by ->mk_sem.  The manipulation of ->mk_active_refs
518
+	 *	    associated with this field is protected by ->mk_sem as well.
477519 	 */
478520 	struct fscrypt_master_key_secret	mk_secret;
479
-	struct rw_semaphore			mk_secret_sem;
480521 
481522 	/*
482523 	 * For v1 policy keys: an arbitrary key descriptor which was assigned by
....@@ -495,21 +536,11 @@
495536 	 *
496537 	 * This is NULL for v1 policy keys; those can only be added by root.
497538 	 *
498
-	 * Locking: in addition to this keyrings own semaphore, this is
499
-	 * protected by the master key's key->sem, so we can do atomic
500
-	 * search+insert.  It can also be searched without taking any locks, but
501
-	 * in that case the returned key may have already been removed.
539
+	 * Locking: protected by ->mk_sem.  (We don't just rely on the keyrings
540
+	 * subsystem semaphore ->mk_users->sem, as we need support for atomic
541
+	 * search+insert along with proper synchronization with ->mk_secret.)
502542 	 */
503543 	struct key		*mk_users;
504
-
505
-	/*
506
-	 * Length of ->mk_decrypted_inodes, plus one if mk_secret is present.
507
-	 * Once this goes to 0, the master key is removed from ->s_master_keys.
508
-	 * The 'struct fscrypt_master_key' will continue to live as long as the
509
-	 * 'struct key' whose payload it is, but we won't let this reference
510
-	 * count rise again.
511
-	 */
512
-	refcount_t		mk_refcount;
513544 
514545 	/*
515546 	 * List of inodes that were unlocked using this key.  This allows the
....@@ -522,9 +553,9 @@
522553 	 * Per-mode encryption keys for the various types of encryption policies
523554 	 * that use them.  Allocated and derived on-demand.
524555 	 */
525
-	struct fscrypt_prepared_key mk_direct_keys[__FSCRYPT_MODE_MAX + 1];
526
-	struct fscrypt_prepared_key mk_iv_ino_lblk_64_keys[__FSCRYPT_MODE_MAX + 1];
527
-	struct fscrypt_prepared_key mk_iv_ino_lblk_32_keys[__FSCRYPT_MODE_MAX + 1];
556
+	struct fscrypt_prepared_key mk_direct_keys[FSCRYPT_MODE_MAX + 1];
557
+	struct fscrypt_prepared_key mk_iv_ino_lblk_64_keys[FSCRYPT_MODE_MAX + 1];
558
+	struct fscrypt_prepared_key mk_iv_ino_lblk_32_keys[FSCRYPT_MODE_MAX + 1];
528559 
529560 	/* Hash key for inode numbers.  Initialized only when needed. */
530561 	siphash_key_t		mk_ino_hash_key;
....@@ -536,11 +567,11 @@
536567 is_master_key_secret_present(const struct fscrypt_master_key_secret *secret)
537568 {
538569 	/*
539
-	 * The READ_ONCE() is only necessary for fscrypt_drop_inode() and
540
-	 * fscrypt_key_describe().  These run in atomic context, so they can't
541
-	 * take ->mk_secret_sem and thus 'secret' can change concurrently which
542
-	 * would be a data race.  But they only need to know whether the secret
543
-	 * *was* present at the time of check, so READ_ONCE() suffices.
570
+	 * The READ_ONCE() is only necessary for fscrypt_drop_inode().
571
+	 * fscrypt_drop_inode() runs in atomic context, so it can't take the key
572
+	 * semaphore and thus 'secret' can change concurrently which would be a
573
+	 * data race.  But fscrypt_drop_inode() only need to know whether the
574
+	 * secret *was* present at the time of check, so READ_ONCE() suffices.
544575 	 */
545576 	return READ_ONCE(secret->size) != 0;
546577 }
....@@ -568,7 +599,11 @@
568599 	return 0;
569600 }
570601 
571
-struct key *
602
+void fscrypt_put_master_key(struct fscrypt_master_key *mk);
603
+
604
+void fscrypt_put_master_key_activeref(struct fscrypt_master_key *mk);
605
+
606
+struct fscrypt_master_key *
572607 fscrypt_find_master_key(struct super_block *sb,
573608 			const struct fscrypt_key_specifier *mk_spec);
574609 
....@@ -585,8 +620,9 @@
585620 struct fscrypt_mode {
586621 	const char *friendly_name;
587622 	const char *cipher_str;
588
-	int keysize;
589
-	int ivsize;
623
+	int keysize;		/* key size in bytes */
624
+	int security_strength;	/* security strength in bytes */
625
+	int ivsize;		/* IV size in bytes */
590626 	int logged_impl_name;
591627 	enum blk_crypto_mode_num blk_crypto_mode;
592628 };
....@@ -603,6 +639,37 @@
603639 
604640 int fscrypt_derive_dirhash_key(struct fscrypt_info *ci,
605641 			       const struct fscrypt_master_key *mk);
642
+
643
+void fscrypt_hash_inode_number(struct fscrypt_info *ci,
644
+			       const struct fscrypt_master_key *mk);
645
+
646
+int fscrypt_get_encryption_info(struct inode *inode, bool allow_unsupported);
647
+
648
+/**
649
+ * fscrypt_require_key() - require an inode's encryption key
650
+ * @inode: the inode we need the key for
651
+ *
652
+ * If the inode is encrypted, set up its encryption key if not already done.
653
+ * Then require that the key be present and return -ENOKEY otherwise.
654
+ *
655
+ * No locks are needed, and the key will live as long as the struct inode --- so
656
+ * it won't go away from under you.
657
+ *
658
+ * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code
659
+ * if a problem occurred while setting up the encryption key.
660
+ */
661
+static inline int fscrypt_require_key(struct inode *inode)
662
+{
663
+	if (IS_ENCRYPTED(inode)) {
664
+		int err = fscrypt_get_encryption_info(inode, false);
665
+
666
+		if (err)
667
+			return err;
668
+		if (!fscrypt_has_encryption_key(inode))
669
+			return -ENOKEY;
670
+	}
671
+	return 0;
672
+}
606673 
607674 /* keysetup_v1.c */
608675 
....@@ -622,5 +689,6 @@
622689 int fscrypt_policy_from_context(union fscrypt_policy *policy_u,
623690 				const union fscrypt_context *ctx_u,
624691 				int ctx_size);
692
+const union fscrypt_policy *fscrypt_policy_to_inherit(struct inode *dir);
625693 
626694 #endif /* _FSCRYPT_PRIVATE_H */