linux/fs/crypto
Eric Biggers 2fc2b430f5 fscrypt: fix derivation of SipHash keys on big endian CPUs
Typically, the cryptographic APIs that fscrypt uses take keys as byte
arrays, which avoids endianness issues.  However, siphash_key_t is an
exception.  It is defined as 'u64 key[2];', i.e. the 128-bit key is
expected to be given directly as two 64-bit words in CPU endianness.

fscrypt_derive_dirhash_key() and fscrypt_setup_iv_ino_lblk_32_key()
forgot to take this into account.  Therefore, the SipHash keys used to
index encrypted+casefolded directories differ on big endian vs. little
endian platforms, as do the SipHash keys used to hash inode numbers for
IV_INO_LBLK_32-encrypted directories.  This makes such directories
non-portable between these platforms.

Fix this by always using the little endian order.  This is a breaking
change for big endian platforms, but this should be fine in practice
since these features (encrypt+casefold support, and the IV_INO_LBLK_32
flag) aren't known to actually be used on any big endian platforms yet.

Fixes: aa408f835d ("fscrypt: derive dirhash key for casefolded directories")
Fixes: e3b1078bed ("fscrypt: add support for IV_INO_LBLK_32 policies")
Cc: <stable@vger.kernel.org> # v5.6+
Link: https://lore.kernel.org/r/20210605075033.54424-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
2021-06-05 00:52:52 -07:00
..
bio.c block: rename BIO_MAX_PAGES to BIO_MAX_VECS 2021-03-11 07:47:48 -07:00
crypto.c
fname.c fscrypt: don't ignore minor_hash when hash is 0 2021-06-05 00:22:53 -07:00
fscrypt_private.h f2fs-for-5.11-rc1 2020-12-17 11:18:00 -08:00
hkdf.c
hooks.c f2fs-for-5.11-rc1 2020-12-17 11:18:00 -08:00
inline_crypt.c
Kconfig fscrypt: relax Kconfig dependencies for crypto API algorithms 2021-04-22 17:31:32 +10:00
keyring.c fscrypt: simplify master key locking 2020-11-24 15:29:47 -08:00
keysetup_v1.c
keysetup.c fscrypt: fix derivation of SipHash keys on big endian CPUs 2021-06-05 00:52:52 -07:00
Makefile
policy.c inode: make init and permission helpers idmapped mount aware 2021-01-24 14:27:16 +01:00