Re: [f2fs-dev] [PATCH] f2fs: don't use casefolded comparison for "." and ".."

[Jaegeuk Kim <jaegeuk@kernel.org>]

Thanks, applied.

On 05/16, Gabriel Krisman Bertazi wrote:
> Eric Biggers <ebiggers@kernel.org> writes:
> 
> > From: Eric Biggers <ebiggers@google.com>
> >
> > Tryng to rename a directory that has all following properties fails with
> > EINVAL and triggers the 'WARN_ON_ONCE(!fscrypt_has_encryption_key(dir))'
> > in f2fs_match_ci_name():
> >
> >     - The directory is casefolded
> >     - The directory is encrypted
> >     - The directory's encryption key is not yet set up
> >     - The parent directory is *not* encrypted
> >
> > The problem is incorrect handling of the lookup of ".." to get the
> > parent reference to update.  fscrypt_setup_filename() treats ".." (and
> > ".") specially, as it's never encrypted.  It's passed through as-is, and
> > setting up the directory's key is not attempted.  As the name isn't a
> > no-key name, f2fs treats it as a "normal" name and attempts a casefolded
> > comparison.  That breaks the assumption of the WARN_ON_ONCE() in
> > f2fs_match_ci_name() which assumes that for encrypted directories,
> > casefolded comparisons only happen when the directory's key is set up.
> >
> > We could just remove this WARN_ON_ONCE().  However, since casefolding is
> > always a no-op on "." and ".." anyway, let's instead just not casefold
> > these names.  This results in the standard bytewise comparison.
> >
> > Fixes: 7ad08a58bf67 ("f2fs: Handle casefolding with Encryption")
> > Cc: <stable@vger.kernel.org> # v5.11+
> > Signed-off-by: Eric Biggers <ebiggers@google.com>
> > ---
> >  fs/f2fs/dir.c  |  3 ++-
> >  fs/f2fs/f2fs.h | 10 +++++-----
> >  fs/f2fs/hash.c | 11 ++++++-----
> >  3 files changed, 13 insertions(+), 11 deletions(-)
> 
> Hi Eric,
> 
> This looks good to me:
> 
> Reviewed-by: Gabriel Krisman Bertazi <krisman@collabora.com>
> 
> Thanks,
> 
> -- 
> Gabriel Krisman Bertazi
> 
> 
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