linux-ext4 - Re: [PATCH v2 27/28] ext4: xattr inode deduplication

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAAeU0aN+Ts=SqGFEMOer=rguprDNX4Mo1Eyj+j1Y=dd-zdbkZw@mail.gmail.com>
Date:   Fri, 2 Jun 2017 05:46:22 -0700
From:   Tahsin Erdogan <tahsin@...gle.com>
To:     "Darrick J. Wong" <darrick.wong@...cle.com>
Cc:     Jan Kara <jack@...e.com>, "Theodore Ts'o" <tytso@....edu>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Dave Kleikamp <shaggy@...nel.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Mark Fasheh <mfasheh@...sity.com>,
        Joel Becker <jlbec@...lplan.org>, Jens Axboe <axboe@...com>,
        Deepa Dinamani <deepa.kernel@...il.com>,
        Mike Christie <mchristi@...hat.com>,
        Fabian Frederick <fabf@...net.be>, linux-ext4@...r.kernel.org,
        linux-kernel@...r.kernel.org, jfs-discussion@...ts.sourceforge.net,
        linux-fsdevel@...r.kernel.org, ocfs2-devel@....oracle.com,
        reiserfs-devel@...r.kernel.org
Subject: Re: [PATCH v2 27/28] ext4: xattr inode deduplication

> Hmm... normally we'd supply sbi->s_csum_seed as the second argument so
> that the metadata checksum value also has the fs uuid stamped into it.

I have thought about using sbi->s_csum_seed and was a little hesitant
because it involves adding more complexity to e2fsprogs to handle
cases like changing uuid or turning off metadata_csum. After thinking
more about this, I think it is doable.

> Even if you dismiss that, we usually follow the convention of
> initializing the crc32c calculation with (~0U), not (0U), to strengthen
> crc32c's ability to detect zeroes being injected at the start of the
> stream.

Agreed, using ~0 is definitely better than 0.