alistair23-linux/fs/crypto/Kconfig
Eric Biggers bd0d97b719 fscrypt: switch fscrypt_do_sha256() to use the SHA-256 library
fscrypt_do_sha256() is only used for hashing encrypted filenames to
create no-key tokens, which isn't performance-critical.  Therefore a C
implementation of SHA-256 is sufficient.

Also, the logic to create no-key tokens is always potentially needed.
This differs from fscrypt's other dependencies on crypto API algorithms,
which are conditionally needed depending on what encryption policies
userspace is using.  Therefore, for fscrypt there isn't much benefit to
allowing SHA-256 to be a loadable module.

So, make fscrypt_do_sha256() use the SHA-256 library instead of the
crypto_shash API.  This is much simpler, since it avoids having to
implement one-time-init (which is hard to do correctly, and in fact was
implemented incorrectly) and handle failures to allocate the
crypto_shash object.

Fixes: edc440e3d2 ("fscrypt: improve format of no-key names")
Cc: Daniel Rosenberg <drosen@google.com>
Link: https://lore.kernel.org/r/20200721225920.114347-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
2020-07-21 16:02:13 -07:00

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# SPDX-License-Identifier: GPL-2.0-only
config FS_ENCRYPTION
bool "FS Encryption (Per-file encryption)"
select CRYPTO
select CRYPTO_HASH
select CRYPTO_SKCIPHER
select CRYPTO_LIB_SHA256
select KEYS
help
Enable encryption of files and directories. This
feature is similar to ecryptfs, but it is more memory
efficient since it avoids caching the encrypted and
decrypted pages in the page cache. Currently Ext4,
F2FS and UBIFS make use of this feature.
# Filesystems supporting encryption must select this if FS_ENCRYPTION. This
# allows the algorithms to be built as modules when all the filesystems are.
config FS_ENCRYPTION_ALGS
tristate
select CRYPTO_AES
select CRYPTO_CBC
select CRYPTO_CTS
select CRYPTO_ECB
select CRYPTO_HMAC
select CRYPTO_SHA512
select CRYPTO_XTS
config FS_ENCRYPTION_INLINE_CRYPT
bool "Enable fscrypt to use inline crypto"
depends on FS_ENCRYPTION && BLK_INLINE_ENCRYPTION
help
Enable fscrypt to use inline encryption hardware if available.