ubifs: require key for truncate(2) of encrypted file
authorEric Biggers <ebiggers@google.com>
Tue, 13 Jun 2017 23:47:55 +0000 (16:47 -0700)
committerRichard Weinberger <richard@nod.at>
Wed, 5 Jul 2017 21:52:50 +0000 (23:52 +0200)
commit4afb9996a254a8ec33801f4b33992d45670164b2
tree0bb8a31b3d354500529bf0abe026ca586f982dbc
parent32c1431eea4881a6b17bd7c639315010aeefa452
ubifs: require key for truncate(2) of encrypted file

Currently, filesystems allow truncate(2) on an encrypted file without
the encryption key.  However, it's impossible to correctly handle the
case where the size being truncated to is not a multiple of the
filesystem block size, because that would require decrypting the final
block, zeroing the part beyond i_size, then encrypting the block.

As other modifications to encrypted file contents are prohibited without
the key, just prohibit truncate(2) as well, making it fail with ENOKEY.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
fs/ubifs/file.c