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

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: <20080108225820.GA9735@elf.ucw.cz>
Date:	Tue, 8 Jan 2008 23:58:20 +0100
From:	Pavel Machek <pavel@....cz>
To:	Miklos Szeredi <miklos@...redi.hu>
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

On Tue 2008-01-08 23:42:20, Miklos Szeredi wrote:
> > On Tue 2008-01-08 12:35:09, Miklos Szeredi wrote:
> > > From: Miklos Szeredi <mszeredi@...e.cz>
> > > 
> > > Use FS_SAFE for "fuse" fs type, but not for "fuseblk".
> > > 
> > > FUSE was designed from the beginning to be safe for unprivileged users.  This
> > > has also been verified in practice over many years.  In addition unprivileged
> > 
> > Eh? So 'kill -9 no longer works' and 'suspend no longer works' is not
> > considered important enough to even mention?
> 
> No.  Because in practice they don't seem to matter.  Also because
> there's no way in which fuse could be done differently to address
> these issues.
> 
> The 'kill -9' thing is basically due to VFS level locking not being
> interruptible.  It could be changed, but I'm not sure it's worth it.

Well, I believe it should be changed. "You need to mount /sys, then
echo X to Y before kill -9 works" does not look nice... I agree it is
not easy.

> > '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?

> 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... and I'm woried about problems fuse + user mounts
expose in other parts of system.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
--
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/