1 // SPDX-License-Identifier: GPL-2.0
18 		.friendly_name = "AES-256-XTS",
26 		.friendly_name = "AES-256-CBC-CTS",
33 		.friendly_name = "AES-128-CBC-ESSIV",
41 		.friendly_name = "AES-128-CBC-CTS",
48 		.friendly_name = "SM4-XTS",
56 		.friendly_name = "SM4-CBC-CTS",
71 		.friendly_name = "AES-256-HCTR2",
87 	if (S_ISREG(inode->i_mode))  in select_encryption_mode()
90 	if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))  in select_encryption_mode()
94 		  inode->i_ino, (inode->i_mode & S_IFMT));  in select_encryption_mode()
95 	return ERR_PTR(-EINVAL);  in select_encryption_mode()
98 /* Create a symmetric cipher object for the given encryption mode and key */
100 fscrypt_allocate_skcipher(struct fscrypt_mode *mode, const u8 *raw_key,  in fscrypt_allocate_skcipher()  argument
106 	tfm = crypto_alloc_skcipher(mode->cipher_str, 0, 0);  in fscrypt_allocate_skcipher()
108 		if (PTR_ERR(tfm) == -ENOENT) {  in fscrypt_allocate_skcipher()
111 				     mode->friendly_name, mode->cipher_str);  in fscrypt_allocate_skcipher()
112 			return ERR_PTR(-ENOPKG);  in fscrypt_allocate_skcipher()
115 			    mode->cipher_str, PTR_ERR(tfm));  in fscrypt_allocate_skcipher()
118 	if (!xchg(&mode->logged_cryptoapi_impl, 1)) {  in fscrypt_allocate_skcipher()
122 		 * performance problems by logging the ->cra_driver_name the  in fscrypt_allocate_skcipher()
123 		 * first time a mode is used.  in fscrypt_allocate_skcipher()
126 			mode->friendly_name, crypto_skcipher_driver_name(tfm));  in fscrypt_allocate_skcipher()
128 	if (WARN_ON_ONCE(crypto_skcipher_ivsize(tfm) != mode->ivsize)) {  in fscrypt_allocate_skcipher()
129 		err = -EINVAL;  in fscrypt_allocate_skcipher()
133 	err = crypto_skcipher_setkey(tfm, raw_key, mode->keysize);  in fscrypt_allocate_skcipher()
145  * Prepare the crypto transform object or blk-crypto key in @prep_key, given the
146  * raw key, encryption mode (@ci->ci_mode), flag indicating which encryption
147  * implementation (fs-layer or blk-crypto) will be used (@ci->ci_inlinecrypt),
148  * and IV generation method (@ci->ci_policy.flags).
158 	tfm = fscrypt_allocate_skcipher(ci->ci_mode, raw_key, ci->ci_inode);  in fscrypt_prepare_key()
163 	 * I.e., here we publish ->tfm with a RELEASE barrier so that  in fscrypt_prepare_key()
165 	 * possible for per-mode keys, not for per-file keys.  in fscrypt_prepare_key()
167 	smp_store_release(&prep_key->tfm, tfm);  in fscrypt_prepare_key()
171 /* Destroy a crypto transform object and/or blk-crypto key. */
175 	crypto_free_skcipher(prep_key->tfm);  in fscrypt_destroy_prepared_key()
180 /* Given a per-file encryption key, set up the file's crypto transform object */
184 	ci->ci_owns_key = true;  in fscrypt_set_per_file_enc_key()
185 	return fscrypt_prepare_key(&ci->ci_enc_key, raw_key, ci);  in fscrypt_set_per_file_enc_key()
193 	const struct inode *inode = ci->ci_inode;  in setup_per_mode_enc_key()
194 	const struct super_block *sb = inode->i_sb;  in setup_per_mode_enc_key()
195 	struct fscrypt_mode *mode = ci->ci_mode;  in setup_per_mode_enc_key()  local
196 	const u8 mode_num = mode - fscrypt_modes;  in setup_per_mode_enc_key()
199 	u8 hkdf_info[sizeof(mode_num) + sizeof(sb->s_uuid)];  in setup_per_mode_enc_key()
204 		return -EINVAL;  in setup_per_mode_enc_key()
208 		ci->ci_enc_key = *prep_key;  in setup_per_mode_enc_key()
218 	BUILD_BUG_ON(sizeof(sb->s_uuid) != 16);  in setup_per_mode_enc_key()
222 		memcpy(&hkdf_info[hkdf_infolen], &sb->s_uuid,  in setup_per_mode_enc_key()
223 		       sizeof(sb->s_uuid));  in setup_per_mode_enc_key()
224 		hkdf_infolen += sizeof(sb->s_uuid);  in setup_per_mode_enc_key()
226 	err = fscrypt_hkdf_expand(&mk->mk_secret.hkdf,  in setup_per_mode_enc_key()
228 				  mode_key, mode->keysize);  in setup_per_mode_enc_key()
232 	memzero_explicit(mode_key, mode->keysize);  in setup_per_mode_enc_key()
236 	ci->ci_enc_key = *prep_key;  in setup_per_mode_enc_key()
244  * Derive a SipHash key from the given fscrypt master key and the given
245  * application-specific information string.
248  * as a pair of 64-bit words.  Therefore, on big endian CPUs we have to do an
257 	err = fscrypt_hkdf_expand(&mk->mk_secret.hkdf, context, info, infolen,  in fscrypt_derive_siphash_key()
263 	BUILD_BUG_ON(ARRAY_SIZE(key->key) != 2);  in fscrypt_derive_siphash_key()
264 	le64_to_cpus(&key->key[0]);  in fscrypt_derive_siphash_key()
265 	le64_to_cpus(&key->key[1]);  in fscrypt_derive_siphash_key()
275 					 ci->ci_nonce, FSCRYPT_FILE_NONCE_SIZE,  in fscrypt_derive_dirhash_key()
276 					 &ci->ci_dirhash_key);  in fscrypt_derive_dirhash_key()
279 	ci->ci_dirhash_key_initialized = true;  in fscrypt_derive_dirhash_key()
286 	WARN_ON_ONCE(ci->ci_inode->i_ino == 0);  in fscrypt_hash_inode_number()
287 	WARN_ON_ONCE(!mk->mk_ino_hash_key_initialized);  in fscrypt_hash_inode_number()
289 	ci->ci_hashed_ino = (u32)siphash_1u64(ci->ci_inode->i_ino,  in fscrypt_hash_inode_number()
290 					      &mk->mk_ino_hash_key);  in fscrypt_hash_inode_number()
298 	err = setup_per_mode_enc_key(ci, mk, mk->mk_iv_ino_lblk_32_keys,  in fscrypt_setup_iv_ino_lblk_32_key()
304 	if (!smp_load_acquire(&mk->mk_ino_hash_key_initialized)) {  in fscrypt_setup_iv_ino_lblk_32_key()
308 		if (mk->mk_ino_hash_key_initialized)  in fscrypt_setup_iv_ino_lblk_32_key()
313 						 NULL, 0, &mk->mk_ino_hash_key);  in fscrypt_setup_iv_ino_lblk_32_key()
317 		smp_store_release(&mk->mk_ino_hash_key_initialized, true);  in fscrypt_setup_iv_ino_lblk_32_key()
328 	if (ci->ci_inode->i_ino)  in fscrypt_setup_iv_ino_lblk_32_key()
339 	if (ci->ci_policy.v2.flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) {  in fscrypt_setup_v2_file_key()
341 		 * DIRECT_KEY: instead of deriving per-file encryption keys, the  in fscrypt_setup_v2_file_key()
342 		 * per-file nonce will be included in all the IVs.  But unlike  in fscrypt_setup_v2_file_key()
344 		 * with the master key directly but rather derive a per-mode  in fscrypt_setup_v2_file_key()
345 		 * encryption key.  This ensures that the master key is  in fscrypt_setup_v2_file_key()
348 		err = setup_per_mode_enc_key(ci, mk, mk->mk_direct_keys,  in fscrypt_setup_v2_file_key()
350 	} else if (ci->ci_policy.v2.flags &  in fscrypt_setup_v2_file_key()
358 		err = setup_per_mode_enc_key(ci, mk, mk->mk_iv_ino_lblk_64_keys,  in fscrypt_setup_v2_file_key()
361 	} else if (ci->ci_policy.v2.flags &  in fscrypt_setup_v2_file_key()
367 		err = fscrypt_hkdf_expand(&mk->mk_secret.hkdf,  in fscrypt_setup_v2_file_key()
369 					  ci->ci_nonce, FSCRYPT_FILE_NONCE_SIZE,  in fscrypt_setup_v2_file_key()
370 					  derived_key, ci->ci_mode->keysize);  in fscrypt_setup_v2_file_key()
375 		memzero_explicit(derived_key, ci->ci_mode->keysize);  in fscrypt_setup_v2_file_key()
391  * Check whether the size of the given master key (@mk) is appropriate for the
394  * If the file uses a v1 encryption policy, then the master key must be at least
398  * requirement: we require that the size of the master key be at least the
400  * (but in practice we only need to consider @ci->ci_mode, since any other
402  * required key size over @ci->ci_mode).  This allows AES-256-XTS keys to be
403  * derived from a 256-bit master key, which is cryptographically sufficient,
404  * rather than requiring a 512-bit master key which is unnecessarily long.  (We
405  * still allow 512-bit master keys if the user chooses to use them, though.)
412 	if (ci->ci_policy.version == FSCRYPT_POLICY_V1)  in fscrypt_valid_master_key_size()
413 		min_keysize = ci->ci_mode->keysize;  in fscrypt_valid_master_key_size()
415 		min_keysize = ci->ci_mode->security_strength;  in fscrypt_valid_master_key_size()
417 	if (mk->mk_secret.size < min_keysize) {  in fscrypt_valid_master_key_size()
420 			     master_key_spec_type(&mk->mk_spec),  in fscrypt_valid_master_key_size()
421 			     master_key_spec_len(&mk->mk_spec),  in fscrypt_valid_master_key_size()
422 			     (u8 *)&mk->mk_spec.u,  in fscrypt_valid_master_key_size()
423 			     mk->mk_secret.size, min_keysize);  in fscrypt_valid_master_key_size()
430  * Find the master key, then set up the inode's actual encryption key.
432  * If the master key is found in the filesystem-level keyring, then it is
433  * returned in *mk_ret with its semaphore read-locked.  This is needed to ensure
434  * that only one task links the fscrypt_inode_info into ->mk_decrypted_inodes
436  * inode), and to synchronize the master key being removed with a new inode
443 	struct super_block *sb = ci->ci_inode->i_sb;  in setup_file_encryption_key()
452 	err = fscrypt_policy_to_key_spec(&ci->ci_policy, &mk_spec);  in setup_file_encryption_key()
462 		 * Add the test_dummy_encryption key on-demand.  In principle,  in setup_file_encryption_key()
468 		    fscrypt_policies_equal(dummy_policy, &ci->ci_policy)) {  in setup_file_encryption_key()
476 		if (ci->ci_policy.version != FSCRYPT_POLICY_V1)  in setup_file_encryption_key()
477 			return -ENOKEY;  in setup_file_encryption_key()
482 		 * to before the search of ->s_master_keys, since users  in setup_file_encryption_key()
483 		 * shouldn't be able to override filesystem-level keys.  in setup_file_encryption_key()
487 	down_read(&mk->mk_sem);  in setup_file_encryption_key()
489 	if (!mk->mk_present) {  in setup_file_encryption_key()
491 		err = -ENOKEY;  in setup_file_encryption_key()
496 		err = -ENOKEY;  in setup_file_encryption_key()
500 	switch (ci->ci_policy.version) {  in setup_file_encryption_key()
502 		err = fscrypt_setup_v1_file_key(ci, mk->mk_secret.raw);  in setup_file_encryption_key()
509 		err = -EINVAL;  in setup_file_encryption_key()
519 	up_read(&mk->mk_sem);  in setup_file_encryption_key()
531 	if (ci->ci_direct_key)  in put_crypt_info()
532 		fscrypt_put_direct_key(ci->ci_direct_key);  in put_crypt_info()
533 	else if (ci->ci_owns_key)  in put_crypt_info()
534 		fscrypt_destroy_prepared_key(ci->ci_inode->i_sb,  in put_crypt_info()
535 					     &ci->ci_enc_key);  in put_crypt_info()
537 	mk = ci->ci_master_key;  in put_crypt_info()
541 		 * with the master key.  In addition, if we're removing the last  in put_crypt_info()
545 		spin_lock(&mk->mk_decrypted_inodes_lock);  in put_crypt_info()
546 		list_del(&ci->ci_master_key_link);  in put_crypt_info()
547 		spin_unlock(&mk->mk_decrypted_inodes_lock);  in put_crypt_info()
548 		fscrypt_put_master_key_activeref(ci->ci_inode->i_sb, mk);  in put_crypt_info()
561 	struct fscrypt_mode *mode;  in fscrypt_setup_encryption_info()  local
565 	res = fscrypt_initialize(inode->i_sb);  in fscrypt_setup_encryption_info()
571 		return -ENOMEM;  in fscrypt_setup_encryption_info()
573 	crypt_info->ci_inode = inode;  in fscrypt_setup_encryption_info()
574 	crypt_info->ci_policy = *policy;  in fscrypt_setup_encryption_info()
575 	memcpy(crypt_info->ci_nonce, nonce, FSCRYPT_FILE_NONCE_SIZE);  in fscrypt_setup_encryption_info()
577 	mode = select_encryption_mode(&crypt_info->ci_policy, inode);  in fscrypt_setup_encryption_info()
578 	if (IS_ERR(mode)) {  in fscrypt_setup_encryption_info()
579 		res = PTR_ERR(mode);  in fscrypt_setup_encryption_info()
582 	WARN_ON_ONCE(mode->ivsize > FSCRYPT_MAX_IV_SIZE);  in fscrypt_setup_encryption_info()
583 	crypt_info->ci_mode = mode;  in fscrypt_setup_encryption_info()
585 	crypt_info->ci_data_unit_bits =  in fscrypt_setup_encryption_info()
586 		fscrypt_policy_du_bits(&crypt_info->ci_policy, inode);  in fscrypt_setup_encryption_info()
587 	crypt_info->ci_data_units_per_block_bits =  in fscrypt_setup_encryption_info()
588 		inode->i_blkbits - crypt_info->ci_data_unit_bits;  in fscrypt_setup_encryption_info()
595 	 * For existing inodes, multiple tasks may race to set ->i_crypt_info.  in fscrypt_setup_encryption_info()
597 	 * fscrypt_get_inode_info().  I.e., here we publish ->i_crypt_info with  in fscrypt_setup_encryption_info()
600 	if (cmpxchg_release(&inode->i_crypt_info, NULL, crypt_info) == NULL) {  in fscrypt_setup_encryption_info()
602 		 * We won the race and set ->i_crypt_info to our crypt_info.  in fscrypt_setup_encryption_info()
603 		 * Now link it into the master key's inode list.  in fscrypt_setup_encryption_info()
606 			crypt_info->ci_master_key = mk;  in fscrypt_setup_encryption_info()
607 			refcount_inc(&mk->mk_active_refs);  in fscrypt_setup_encryption_info()
608 			spin_lock(&mk->mk_decrypted_inodes_lock);  in fscrypt_setup_encryption_info()
609 			list_add(&crypt_info->ci_master_key_link,  in fscrypt_setup_encryption_info()
610 				 &mk->mk_decrypted_inodes);  in fscrypt_setup_encryption_info()
611 			spin_unlock(&mk->mk_decrypted_inodes_lock);  in fscrypt_setup_encryption_info()
618 		up_read(&mk->mk_sem);  in fscrypt_setup_encryption_info()
626  * fscrypt_get_encryption_info() - set up an inode's encryption key
634  * Set up ->i_crypt_info, if it hasn't already been done.
636  * Note: unless ->i_crypt_info is already set, this isn't %GFP_NOFS-safe.  So
639  * Return: 0 if ->i_crypt_info was set or was already set, *or* if the
641  *	   distinguish these cases.)  Also can return another -errno code.
652 	res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));  in fscrypt_get_encryption_info()
654 		if (res == -ERANGE && allow_unsupported)  in fscrypt_get_encryption_info()
672 		return -EINVAL;  in fscrypt_get_encryption_info()
678 					    S_ISDIR(inode->i_mode));  in fscrypt_get_encryption_info()
680 	if (res == -ENOPKG && allow_unsupported) /* Algorithm unavailable? */  in fscrypt_get_encryption_info()
682 	if (res == -ENOKEY)  in fscrypt_get_encryption_info()
688  * fscrypt_prepare_new_inode() - prepare to create a new inode in a directory
689  * @dir: a possibly-encrypted directory
690  * @inode: the new inode.  ->i_mode and ->i_blkbits must be set already.
691  *	   ->i_ino doesn't need to be set yet.
694  * If the directory is encrypted, set up its ->i_crypt_info in preparation for
696  * encrypted, set up its ->i_crypt_info and set *encrypt_ret=true.
698  * This isn't %GFP_NOFS-safe, and therefore it should be called before starting
699  * any filesystem transaction to create the inode.  For this reason, ->i_ino
705  * Return: 0 on success, -ENOKEY if the encryption key is missing, or another
706  *	   -errno code
720 	if (WARN_ON_ONCE(inode->i_blkbits == 0))  in fscrypt_prepare_new_inode()
721 		return -EINVAL;  in fscrypt_prepare_new_inode()
723 	if (WARN_ON_ONCE(inode->i_mode == 0))  in fscrypt_prepare_new_inode()
724 		return -EINVAL;  in fscrypt_prepare_new_inode()
730 	if (!S_ISREG(inode->i_mode) &&  in fscrypt_prepare_new_inode()
731 	    !S_ISDIR(inode->i_mode) &&  in fscrypt_prepare_new_inode()
732 	    !S_ISLNK(inode->i_mode))  in fscrypt_prepare_new_inode()
740 					     S_ISDIR(inode->i_mode));  in fscrypt_prepare_new_inode()
745  * fscrypt_put_encryption_info() - free most of an inode's fscrypt data
753 	put_crypt_info(inode->i_crypt_info);  in fscrypt_put_encryption_info()
754 	inode->i_crypt_info = NULL;  in fscrypt_put_encryption_info()
759  * fscrypt_free_inode() - free an inode's fscrypt data requiring RCU delay
767 	if (IS_ENCRYPTED(inode) && S_ISLNK(inode->i_mode)) {  in fscrypt_free_inode()
768 		kfree(inode->i_link);  in fscrypt_free_inode()
769 		inode->i_link = NULL;  in fscrypt_free_inode()
775  * fscrypt_drop_inode() - check whether the inode's master key has been removed
778  * Filesystems supporting fscrypt must call this from their ->drop_inode()
780  * use and their master key has been removed.
790 	 * so it's irrelevant.  If ci_master_key is NULL, then the master key  in fscrypt_drop_inode()
791 	 * was provided via the legacy mechanism of the process-subscribed  in fscrypt_drop_inode()
794 	if (!ci || !ci->ci_master_key)  in fscrypt_drop_inode()
798 	 * With proper, non-racy use of FS_IOC_REMOVE_ENCRYPTION_KEY, all inodes  in fscrypt_drop_inode()
803 	if (inode->i_state & I_DIRTY_ALL)  in fscrypt_drop_inode()
807 	 * We can't take ->mk_sem here, since this runs in atomic context.  in fscrypt_drop_inode()
808 	 * Therefore, ->mk_present can change concurrently, and our result may  in fscrypt_drop_inode()
815 	return !READ_ONCE(ci->ci_master_key->mk_present);  in fscrypt_drop_inode()