linux-kernel - Re: [PATCH 00/23] per device dirty throttling -v8

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: <20070804230007.30857453.akpm@linux-foundation.org>
Date:	Sat, 4 Aug 2007 23:00:07 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Florian Weimer <fw@...eb.enyo.de>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, miklos@...redi.hu, neilb@...e.de,
	dgc@....com, tomoki.sekiyama.qu@...achi.com, nikita@...sterfs.com,
	trond.myklebust@....uio.no, yingchao.zhou@...il.com,
	richard@....demon.co.uk
Subject: Re: [PATCH 00/23] per device dirty throttling -v8

On Sat, 04 Aug 2007 21:16:35 +0200 Florian Weimer <fw@...eb.enyo.de> wrote:

> * Andrew Morton:
> 
> > The easy preventive is to mount with data=writeback.  Maybe that should
> > have been the default.
> 
> The documentation I could find suggests that this may lead to a
> security weakness (old data in blocks of a file that was grown just
> before the crash leaks to a different user).

yup.  This problem also exists in ext2, reiserfs (unless using
ordered-mode), JFS, others.

>  XFS overwrites that data
> with zeros upon reboot, which tends to irritate users when it happens.

yup.

> >From this point of view, data=ordered doesn't seem too bad.

If your computer is used by multiple users who don't trust each other,
sure.  That covers, what?  About 2% of machines?

I was using data=writeback for a while on my most-thrashed disk.  The
results were a bit disappointing - not much difference.  ext2 is a lot
quicker.

(I don't use anything which is fsync-happy, btw).  (I used to have a patch
which sysctl-tunably turned fsync, msync, fdatasync into "return 0" for use
on the laptop but I seem to have lost it)



-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/