linux-kernel - Re: [PATCH] ext4: Fix no-key deletion for encrypt+casefold

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Message-ID: <YLg4JOlrNCRJhY6s@mit.edu>
Date:   Wed, 2 Jun 2021 22:02:12 -0400
From:   "Theodore Ts'o" <tytso@....edu>
To:     Daniel Rosenberg <drosen@...gle.com>
Cc:     Eric Biggers <ebiggers@...nel.org>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org,
        Gabriel Krisman Bertazi <krisman@...labora.com>,
        kernel-team@...roid.com
Subject: Re: [PATCH] ext4: Fix no-key deletion for encrypt+casefold

On Sat, May 22, 2021 at 12:41:32AM +0000, Daniel Rosenberg wrote:
> commit 471fbbea7ff7 ("ext4: handle casefolding with encryption") is
> missing a few checks for the encryption key which are needed to
> support deleting enrypted casefolded files when the key is not
> present.
> 
> Note from ebiggers:
> (These checks for the encryption key are still racy since they happen
> too late, but apparently they worked well enough...)
> 
> This bug made it impossible to delete encrypted+casefolded directories
> without the encryption key, due to errors like:
> 
>     W         : EXT4-fs warning (device vdc): __ext4fs_dirhash:270: inode #49202: comm Binder:378_4: Siphash requires key
> 
> Repro steps in kvm-xfstests test appliance:
>       mkfs.ext4 -F -E encoding=utf8 -O encrypt /dev/vdc
>       mount /vdc
>       mkdir /vdc/dir
>       chattr +F /vdc/dir
>       keyid=$(head -c 64 /dev/zero | xfs_io -c add_enckey /vdc | awk '{print $NF}')
>       xfs_io -c "set_encpolicy $keyid" /vdc/dir
>       for i in `seq 1 100`; do
>           mkdir /vdc/dir/$i
>       done
>       xfs_io -c "rm_enckey $keyid" /vdc
>       rm -rf /vdc/dir # fails with the bug
> 
> Fixes: 471fbbea7ff7 ("ext4: handle casefolding with encryption")
> Signed-off-by: Daniel Rosenberg <drosen@...gle.com>

Applied, thanks.

					- Ted