linux-ext4 - Re: Atomic non-durable file write API

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Message-ID: <AANLkTimQBg-ik=EAN6=tiee2308eQ33jpqu7SnTd08bK@mail.gmail.com>
Date:	Tue, 28 Dec 2010 23:28:31 +0100
From:	Olaf van der Spek <olafvdspek@...il.com>
To:	Greg Freemyer <greg.freemyer@...il.com>
Cc:	Neil Brown <neilb@...e.de>,
	Christian Stroetmann <stroetmann@...olinux.com>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	linux-ext4@...r.kernel.org, "Ted Ts'o" <tytso@....edu>,
	Nick Piggin <npiggin@...il.com>
Subject: Re: Atomic non-durable file write API

On Tue, Dec 28, 2010 at 11:15 PM, Greg Freemyer <greg.freemyer@...il.com> wrote:
> So ACLs are lost?

I'm not sure. Since preserving them might not be easy I think it's
likely they're lost in some cases.

> That seems like a potentially bigger issue than loosing the owner/group info.
>
> And I assume if the owner changes, then the new owner has privileges
> to modify ACLs he didn't have previously.
>
> So if I want to instigate a simple denial of service in a multi-user
> environment, I edit a few key docs that I have privileges to edit.  By
> doing so I take ownership.  As owner I  change the permissions and
> ACLs so that no one but me can access them.
>
> Seems like a security hole to me.

If you have write access you can clear the data as well, so
effectively the difference is small.

Olaf
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