Re: [PATCH 01/24] Unionfs: Documentation

From: Jan Kara
Date: Tue Jan 09 2007 - 07:16:19 EST


> On Mon, Jan 08, 2007 at 11:18:52AM -0800, Andrew Morton wrote:
> > On Sun, 7 Jan 2007 23:12:53 -0500
> > "Josef 'Jeff' Sipek" <jsipek@xxxxxxxxxxxxx> wrote:
> >
<snip>

> > > Any such change can cause Unionfs to oops, or stay
> > > silent and even RESULT IN DATA LOSS.
> >
> > With a rather rough user interface ;)
>
> That statement is meant to scare people away from modifying the lower fs :)
> I tortured unionfs quite a bit, and it can oops but it takes some effort.
But isn't it then potential DOS? If you happen to union two filesystems
and an untrusted user has write access to both original filesystem and
the union, then you say he'd be able to produce oops? That does not
sound very secure to me... And if any secure use of unionfs requires
limitting access to the original trees, then I think it's a good reason
to implement it in unionfs itself. Just my 2 cents.

Honza
--
Jan Kara <jack@xxxxxxx>
SuSE CR Labs
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