linux-kernel - Re: [patch 7/9] unprivileged mounts: allow unprivileged fuse mounts

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Message-Id: <E1JCWxm-0005Fn-36@pomaz-ex.szeredi.hu>
Date:	Wed, 09 Jan 2008 10:11:06 +0100
From:	Miklos Szeredi <miklos@...redi.hu>
To:	pavel@....cz
CC:	akpm@...ux-foundation.org, hch@...radead.org, serue@...ibm.com,
	viro@....linux.org.uk, ebiederm@...ssion.com, kzak@...hat.com,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	containers@...ts.osdl.org, util-linux-ng@...r.kernel.org
Subject: Re: [patch 7/9] unprivileged mounts: allow unprivileged fuse mounts

> > > 'updatedb no longer works' is not a problem?
> > 
> > I haven't seen any problems with updatedb, and haven't had any bug
> > reports about it either.
> 
> Ok, I don't know much about FUSE. In current version, if user creates
> infinite maze and mounts it under ~, updatedb just does not enter it?

It doesn't.  See Documentation/filesystems/fuse.txt

> > AFAIR there were two security vulnerabilities in fuse's history, one
> > of them an information leak in the kernel module, and the other one an
> > mtab corruption issue in the fusermount utility.  I don't think this
> > is such a bad track record.
> 
> Not bad indeed. But I'd consider 'kill -9 not working' to be DoS
> vulnerability...

The worst that can happen is that a sysadmin doesn't read the docs
(likely) before enabling fuse on a multiuser system, and is surprised
by a user doing funny things.  And _then_ has to go read the docs, or
google for some info.  This is basically how things normally work, and
I don't consider it a DoS.

> and I'm woried about problems fuse + user mounts expose in other
> parts of system.

I'm worried too, and I'm not saying that enabling unprivileged fuse
mounts is completely risk free.  Nothing is, and nobody is forced to
do it.

Miklos
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