diff options
author | Eric Biggers <ebiggers@google.com> | 2021-06-05 00:50:33 -0700 |
---|---|---|
committer | Eric Biggers <ebiggers@google.com> | 2021-06-05 00:52:52 -0700 |
commit | 2fc2b430f559fdf32d5d1dd5ceaa40e12fb77bdf (patch) | |
tree | 51d7c56bf08bbe81e4761999e73ff93939ea9706 /security | |
parent | 77f30bfcfcf484da7208affd6a9e63406420bf91 (diff) |
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: aa408f835d02 ("fscrypt: derive dirhash key for casefolded directories")
Fixes: e3b1078bedd3 ("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>
Diffstat (limited to 'security')
0 files changed, 0 insertions, 0 deletions