• Jaegeuk Kim's avatar
    f2fs: check entire encrypted bigname when finding a dentry · 6332cd32
    Jaegeuk Kim authored
    If user has no key under an encrypted dir, fscrypt gives digested dentries.
    Previously, when looking up a dentry, f2fs only checks its hash value with
    first 4 bytes of the digested dentry, which didn't handle hash collisions fully.
    This patch enhances to check entire dentry bytes likewise ext4.
    
    Eric reported how to reproduce this issue by:
    
     # seq -f "edir/abcdefghijklmnopqrstuvwxyz012345%.0f" 100000 | xargs touch
     # find edir -type f | xargs stat -c %i | sort | uniq | wc -l
    100000
     # sync
     # echo 3 > /proc/sys/vm/drop_caches
     # keyctl new_session
     # find edir -type f | xargs stat -c %i | sort | uniq | wc -l
    99999
    
    Cc: <stable@vger.kernel.org>
    Reported-by: 's avatarEric Biggers <ebiggers@google.com>
    Signed-off-by: 's avatarJaegeuk Kim <jaegeuk@kernel.org>
    (fixed f2fs_dentry_hash() to work even when the hash is 0)
    Signed-off-by: 's avatarEric Biggers <ebiggers@google.com>
    Signed-off-by: 's avatarTheodore Ts'o <tytso@mit.edu>
    6332cd32