fscrypt: invoke crypto API for ESSIV handling
Instead of open-coding the calculations for ESSIV handling, use an ESSIV
skcipher which does all of this under the hood. ESSIV was added to the
crypto API in v5.4.
This is based on a patch from Ard Biesheuvel, but reworked to apply
after all the fscrypt changes that went into v5.4.
Tested with 'kvm-xfstests -c ext4,f2fs -g encrypt', including the
ciphertext verification tests for v1 and v2 encryption policies.
Originally-from: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
diff --git a/Documentation/filesystems/fscrypt.rst b/Documentation/filesystems/fscrypt.rst
index 8a0700a..6ec459b 100644
--- a/Documentation/filesystems/fscrypt.rst
+++ b/Documentation/filesystems/fscrypt.rst
@@ -308,8 +308,9 @@
AES-128-CBC was added only for low-powered embedded devices with
crypto accelerators such as CAAM or CESA that do not support XTS. To
-use AES-128-CBC, CONFIG_CRYPTO_SHA256 (or another SHA-256
-implementation) must be enabled so that ESSIV can be used.
+use AES-128-CBC, CONFIG_CRYPTO_ESSIV and CONFIG_CRYPTO_SHA256 (or
+another SHA-256 implementation) must be enabled so that ESSIV can be
+used.
Adiantum is a (primarily) stream cipher-based mode that is fast even
on CPUs without dedicated crypto instructions. It's also a true
