1 // SPDX-License-Identifier: GPL-2.0
18 		.friendly_name = "AES-256-XTS",
26 		.friendly_name = "AES-256-CTS-CBC",
33 		.friendly_name = "AES-128-CBC-ESSIV",
41 		.friendly_name = "AES-128-CTS-CBC",
56 		.friendly_name = "AES-256-HCTR2",
72 	if (S_ISREG(inode->i_mode))  in select_encryption_mode()
75 	if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))  in select_encryption_mode()
79 		  inode->i_ino, (inode->i_mode & S_IFMT));  in select_encryption_mode()
80 	return ERR_PTR(-EINVAL);  in select_encryption_mode()
91 	tfm = crypto_alloc_skcipher(mode->cipher_str, 0, 0);  in fscrypt_allocate_skcipher()
93 		if (PTR_ERR(tfm) == -ENOENT) {  in fscrypt_allocate_skcipher()
96 				     mode->friendly_name, mode->cipher_str);  in fscrypt_allocate_skcipher()
97 			return ERR_PTR(-ENOPKG);  in fscrypt_allocate_skcipher()
100 			    mode->cipher_str, PTR_ERR(tfm));  in fscrypt_allocate_skcipher()
103 	if (!xchg(&mode->logged_cryptoapi_impl, 1)) {  in fscrypt_allocate_skcipher()
107 		 * performance problems by logging the ->cra_driver_name the  in fscrypt_allocate_skcipher()
111 			mode->friendly_name, crypto_skcipher_driver_name(tfm));  in fscrypt_allocate_skcipher()
113 	if (WARN_ON(crypto_skcipher_ivsize(tfm) != mode->ivsize)) {  in fscrypt_allocate_skcipher()
114 		err = -EINVAL;  in fscrypt_allocate_skcipher()
118 	err = crypto_skcipher_setkey(tfm, raw_key, mode->keysize);  in fscrypt_allocate_skcipher()
130  * Prepare the crypto transform object or blk-crypto key in @prep_key, given the
131  * raw key, encryption mode (@ci->ci_mode), flag indicating which encryption
132  * implementation (fs-layer or blk-crypto) will be used (@ci->ci_inlinecrypt),
133  * and IV generation method (@ci->ci_policy.flags).
143 	tfm = fscrypt_allocate_skcipher(ci->ci_mode, raw_key, ci->ci_inode);  in fscrypt_prepare_key()
148 	 * I.e., here we publish ->tfm with a RELEASE barrier so that  in fscrypt_prepare_key()
150 	 * possible for per-mode keys, not for per-file keys.  in fscrypt_prepare_key()
152 	smp_store_release(&prep_key->tfm, tfm);  in fscrypt_prepare_key()
156 /* Destroy a crypto transform object and/or blk-crypto key. */
160 	crypto_free_skcipher(prep_key->tfm);  in fscrypt_destroy_prepared_key()
165 /* Given a per-file encryption key, set up the file's crypto transform object */
168 	ci->ci_owns_key = true;  in fscrypt_set_per_file_enc_key()
169 	return fscrypt_prepare_key(&ci->ci_enc_key, raw_key, ci);  in fscrypt_set_per_file_enc_key()
174 				  struct fscrypt_prepared_key *keys,  in setup_per_mode_enc_key()  argument
177 	const struct inode *inode = ci->ci_inode;  in setup_per_mode_enc_key()
178 	const struct super_block *sb = inode->i_sb;  in setup_per_mode_enc_key()
179 	struct fscrypt_mode *mode = ci->ci_mode;  in setup_per_mode_enc_key()
180 	const u8 mode_num = mode - fscrypt_modes;  in setup_per_mode_enc_key()
183 	u8 hkdf_info[sizeof(mode_num) + sizeof(sb->s_uuid)];  in setup_per_mode_enc_key()
188 		return -EINVAL;  in setup_per_mode_enc_key()
190 	prep_key = &keys[mode_num];  in setup_per_mode_enc_key()
192 		ci->ci_enc_key = *prep_key;  in setup_per_mode_enc_key()
202 	BUILD_BUG_ON(sizeof(sb->s_uuid) != 16);  in setup_per_mode_enc_key()
206 		memcpy(&hkdf_info[hkdf_infolen], &sb->s_uuid,  in setup_per_mode_enc_key()
207 		       sizeof(sb->s_uuid));  in setup_per_mode_enc_key()
208 		hkdf_infolen += sizeof(sb->s_uuid);  in setup_per_mode_enc_key()
210 	err = fscrypt_hkdf_expand(&mk->mk_secret.hkdf,  in setup_per_mode_enc_key()
212 				  mode_key, mode->keysize);  in setup_per_mode_enc_key()
216 	memzero_explicit(mode_key, mode->keysize);  in setup_per_mode_enc_key()
220 	ci->ci_enc_key = *prep_key;  in setup_per_mode_enc_key()
229  * application-specific information string.
232  * as a pair of 64-bit words.  Therefore, on big endian CPUs we have to do an
241 	err = fscrypt_hkdf_expand(&mk->mk_secret.hkdf, context, info, infolen,  in fscrypt_derive_siphash_key()
247 	BUILD_BUG_ON(ARRAY_SIZE(key->key) != 2);  in fscrypt_derive_siphash_key()
248 	le64_to_cpus(&key->key[0]);  in fscrypt_derive_siphash_key()
249 	le64_to_cpus(&key->key[1]);  in fscrypt_derive_siphash_key()
259 					 ci->ci_nonce, FSCRYPT_FILE_NONCE_SIZE,  in fscrypt_derive_dirhash_key()
260 					 &ci->ci_dirhash_key);  in fscrypt_derive_dirhash_key()
263 	ci->ci_dirhash_key_initialized = true;  in fscrypt_derive_dirhash_key()
270 	WARN_ON(ci->ci_inode->i_ino == 0);  in fscrypt_hash_inode_number()
271 	WARN_ON(!mk->mk_ino_hash_key_initialized);  in fscrypt_hash_inode_number()
273 	ci->ci_hashed_ino = (u32)siphash_1u64(ci->ci_inode->i_ino,  in fscrypt_hash_inode_number()
274 					      &mk->mk_ino_hash_key);  in fscrypt_hash_inode_number()
282 	err = setup_per_mode_enc_key(ci, mk, mk->mk_iv_ino_lblk_32_keys,  in fscrypt_setup_iv_ino_lblk_32_key()
288 	if (!smp_load_acquire(&mk->mk_ino_hash_key_initialized)) {  in fscrypt_setup_iv_ino_lblk_32_key()
292 		if (mk->mk_ino_hash_key_initialized)  in fscrypt_setup_iv_ino_lblk_32_key()
293 			goto unlock;  in fscrypt_setup_iv_ino_lblk_32_key()
297 						 NULL, 0, &mk->mk_ino_hash_key);  in fscrypt_setup_iv_ino_lblk_32_key()
299 			goto unlock;  in fscrypt_setup_iv_ino_lblk_32_key()
301 		smp_store_release(&mk->mk_ino_hash_key_initialized, true);  in fscrypt_setup_iv_ino_lblk_32_key()
302 unlock:  in fscrypt_setup_iv_ino_lblk_32_key()
312 	if (ci->ci_inode->i_ino)  in fscrypt_setup_iv_ino_lblk_32_key()
323 	if (ci->ci_policy.v2.flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) {  in fscrypt_setup_v2_file_key()
325 		 * DIRECT_KEY: instead of deriving per-file encryption keys, the  in fscrypt_setup_v2_file_key()
326 		 * per-file nonce will be included in all the IVs.  But unlike  in fscrypt_setup_v2_file_key()
328 		 * with the master key directly but rather derive a per-mode  in fscrypt_setup_v2_file_key()
332 		err = setup_per_mode_enc_key(ci, mk, mk->mk_direct_keys,  in fscrypt_setup_v2_file_key()
334 	} else if (ci->ci_policy.v2.flags &  in fscrypt_setup_v2_file_key()
337 		 * IV_INO_LBLK_64: encryption keys are derived from (master_key,  in fscrypt_setup_v2_file_key()
342 		err = setup_per_mode_enc_key(ci, mk, mk->mk_iv_ino_lblk_64_keys,  in fscrypt_setup_v2_file_key()
345 	} else if (ci->ci_policy.v2.flags &  in fscrypt_setup_v2_file_key()
351 		err = fscrypt_hkdf_expand(&mk->mk_secret.hkdf,  in fscrypt_setup_v2_file_key()
353 					  ci->ci_nonce, FSCRYPT_FILE_NONCE_SIZE,  in fscrypt_setup_v2_file_key()
354 					  derived_key, ci->ci_mode->keysize);  in fscrypt_setup_v2_file_key()
359 		memzero_explicit(derived_key, ci->ci_mode->keysize);  in fscrypt_setup_v2_file_key()
384  * (but in practice we only need to consider @ci->ci_mode, since any other
386  * required key size over @ci->ci_mode).  This allows AES-256-XTS keys to be
387  * derived from a 256-bit master key, which is cryptographically sufficient,
388  * rather than requiring a 512-bit master key which is unnecessarily long.  (We
389  * still allow 512-bit master keys if the user chooses to use them, though.)
396 	if (ci->ci_policy.version == FSCRYPT_POLICY_V1)  in fscrypt_valid_master_key_size()
397 		min_keysize = ci->ci_mode->keysize;  in fscrypt_valid_master_key_size()
399 		min_keysize = ci->ci_mode->security_strength;  in fscrypt_valid_master_key_size()
401 	if (mk->mk_secret.size < min_keysize) {  in fscrypt_valid_master_key_size()
404 			     master_key_spec_type(&mk->mk_spec),  in fscrypt_valid_master_key_size()
405 			     master_key_spec_len(&mk->mk_spec),  in fscrypt_valid_master_key_size()
406 			     (u8 *)&mk->mk_spec.u,  in fscrypt_valid_master_key_size()
407 			     mk->mk_secret.size, min_keysize);  in fscrypt_valid_master_key_size()
416  * If the master key is found in the filesystem-level keyring, then it is
417  * returned in *mk_ret with its semaphore read-locked.  This is needed to ensure
418  * that only one task links the fscrypt_info into ->mk_decrypted_inodes (as
434 	err = fscrypt_policy_to_key_spec(&ci->ci_policy, &mk_spec);  in setup_file_encryption_key()
438 	mk = fscrypt_find_master_key(ci->ci_inode->i_sb, &mk_spec);  in setup_file_encryption_key()
440 		if (ci->ci_policy.version != FSCRYPT_POLICY_V1)  in setup_file_encryption_key()
441 			return -ENOKEY;  in setup_file_encryption_key()
446 		 * to before the search of ->s_master_keys, since users  in setup_file_encryption_key()
447 		 * shouldn't be able to override filesystem-level keys.  in setup_file_encryption_key()
451 	down_read(&mk->mk_sem);  in setup_file_encryption_key()
454 	if (!is_master_key_secret_present(&mk->mk_secret)) {  in setup_file_encryption_key()
455 		err = -ENOKEY;  in setup_file_encryption_key()
460 		err = -ENOKEY;  in setup_file_encryption_key()
464 	switch (ci->ci_policy.version) {  in setup_file_encryption_key()
466 		err = fscrypt_setup_v1_file_key(ci, mk->mk_secret.raw);  in setup_file_encryption_key()
473 		err = -EINVAL;  in setup_file_encryption_key()
483 	up_read(&mk->mk_sem);  in setup_file_encryption_key()
495 	if (ci->ci_direct_key)  in put_crypt_info()
496 		fscrypt_put_direct_key(ci->ci_direct_key);  in put_crypt_info()
497 	else if (ci->ci_owns_key)  in put_crypt_info()
498 		fscrypt_destroy_prepared_key(ci->ci_inode->i_sb,  in put_crypt_info()
499 					     &ci->ci_enc_key);  in put_crypt_info()
501 	mk = ci->ci_master_key;  in put_crypt_info()
509 		spin_lock(&mk->mk_decrypted_inodes_lock);  in put_crypt_info()
510 		list_del(&ci->ci_master_key_link);  in put_crypt_info()
511 		spin_unlock(&mk->mk_decrypted_inodes_lock);  in put_crypt_info()
529 	res = fscrypt_initialize(inode->i_sb->s_cop->flags);  in fscrypt_setup_encryption_info()
535 		return -ENOMEM;  in fscrypt_setup_encryption_info()
537 	crypt_info->ci_inode = inode;  in fscrypt_setup_encryption_info()
538 	crypt_info->ci_policy = *policy;  in fscrypt_setup_encryption_info()
539 	memcpy(crypt_info->ci_nonce, nonce, FSCRYPT_FILE_NONCE_SIZE);  in fscrypt_setup_encryption_info()
541 	mode = select_encryption_mode(&crypt_info->ci_policy, inode);  in fscrypt_setup_encryption_info()
546 	WARN_ON(mode->ivsize > FSCRYPT_MAX_IV_SIZE);  in fscrypt_setup_encryption_info()
547 	crypt_info->ci_mode = mode;  in fscrypt_setup_encryption_info()
554 	 * For existing inodes, multiple tasks may race to set ->i_crypt_info.  in fscrypt_setup_encryption_info()
556 	 * fscrypt_get_info().  I.e., here we publish ->i_crypt_info with a  in fscrypt_setup_encryption_info()
559 	if (cmpxchg_release(&inode->i_crypt_info, NULL, crypt_info) == NULL) {  in fscrypt_setup_encryption_info()
561 		 * We won the race and set ->i_crypt_info to our crypt_info.  in fscrypt_setup_encryption_info()
565 			crypt_info->ci_master_key = mk;  in fscrypt_setup_encryption_info()
566 			refcount_inc(&mk->mk_active_refs);  in fscrypt_setup_encryption_info()
567 			spin_lock(&mk->mk_decrypted_inodes_lock);  in fscrypt_setup_encryption_info()
568 			list_add(&crypt_info->ci_master_key_link,  in fscrypt_setup_encryption_info()
569 				 &mk->mk_decrypted_inodes);  in fscrypt_setup_encryption_info()
570 			spin_unlock(&mk->mk_decrypted_inodes_lock);  in fscrypt_setup_encryption_info()
577 		up_read(&mk->mk_sem);  in fscrypt_setup_encryption_info()
585  * fscrypt_get_encryption_info() - set up an inode's encryption key
593  * Set up ->i_crypt_info, if it hasn't already been done.
595  * Note: unless ->i_crypt_info is already set, this isn't %GFP_NOFS-safe.  So
598  * Return: 0 if ->i_crypt_info was set or was already set, *or* if the
600  *	   distinguish these cases.)  Also can return another -errno code.
611 	res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));  in fscrypt_get_encryption_info()
613 		if (res == -ERANGE && allow_unsupported)  in fscrypt_get_encryption_info()
631 		return -EINVAL;  in fscrypt_get_encryption_info()
637 					    S_ISDIR(inode->i_mode));  in fscrypt_get_encryption_info()
639 	if (res == -ENOPKG && allow_unsupported) /* Algorithm unavailable? */  in fscrypt_get_encryption_info()
641 	if (res == -ENOKEY)  in fscrypt_get_encryption_info()
647  * fscrypt_prepare_new_inode() - prepare to create a new inode in a directory
648  * @dir: a possibly-encrypted directory
649  * @inode: the new inode.  ->i_mode must be set already.
650  *	   ->i_ino doesn't need to be set yet.
653  * If the directory is encrypted, set up its ->i_crypt_info in preparation for
655  * encrypted, set up its ->i_crypt_info and set *encrypt_ret=true.
657  * This isn't %GFP_NOFS-safe, and therefore it should be called before starting
658  * any filesystem transaction to create the inode.  For this reason, ->i_ino
664  * Return: 0 on success, -ENOKEY if the encryption key is missing, or another
665  *	   -errno code
679 	if (WARN_ON_ONCE(inode->i_mode == 0))  in fscrypt_prepare_new_inode()
680 		return -EINVAL;  in fscrypt_prepare_new_inode()
686 	if (!S_ISREG(inode->i_mode) &&  in fscrypt_prepare_new_inode()
687 	    !S_ISDIR(inode->i_mode) &&  in fscrypt_prepare_new_inode()
688 	    !S_ISLNK(inode->i_mode))  in fscrypt_prepare_new_inode()
696 					     S_ISDIR(inode->i_mode));  in fscrypt_prepare_new_inode()
701  * fscrypt_put_encryption_info() - free most of an inode's fscrypt data
709 	put_crypt_info(inode->i_crypt_info);  in fscrypt_put_encryption_info()
710 	inode->i_crypt_info = NULL;  in fscrypt_put_encryption_info()
715  * fscrypt_free_inode() - free an inode's fscrypt data requiring RCU delay
723 	if (IS_ENCRYPTED(inode) && S_ISLNK(inode->i_mode)) {  in fscrypt_free_inode()
724 		kfree(inode->i_link);  in fscrypt_free_inode()
725 		inode->i_link = NULL;  in fscrypt_free_inode()
731  * fscrypt_drop_inode() - check whether the inode's master key has been removed
734  * Filesystems supporting fscrypt must call this from their ->drop_inode()
747 	 * was provided via the legacy mechanism of the process-subscribed  in fscrypt_drop_inode()
750 	if (!ci || !ci->ci_master_key)  in fscrypt_drop_inode()
754 	 * With proper, non-racy use of FS_IOC_REMOVE_ENCRYPTION_KEY, all inodes  in fscrypt_drop_inode()
759 	if (inode->i_state & I_DIRTY_ALL)  in fscrypt_drop_inode()
770 	return !is_master_key_secret_present(&ci->ci_master_key->mk_secret);  in fscrypt_drop_inode()