[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in
From: |
Daniel P. Berrange |
Subject: |
Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in vl.c |
Date: |
Mon, 18 Jun 2012 09:38:46 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Mon, Jun 18, 2012 at 09:31:03AM +0100, Daniel P. Berrange wrote:
> On Fri, Jun 15, 2012 at 05:02:19PM -0400, Paul Moore wrote:
> > On Friday, June 15, 2012 07:06:10 PM Blue Swirl wrote:
> > > I think allowing execve() would render seccomp pretty much useless.
> >
> > Not necessarily.
> >
> > I'll agree that it does seem a bit odd to allow execve(), but there is
> > still
> > value in enabling seccomp to disable potentially buggy/exploitable
> > syscalls.
> > Let's not forget that we have over 300 syscalls on x86_64, not including
> > the
> > 32 bit versions, and even if we add all of the new syscalls suggested in
> > this
> > thread we are still talking about a small subset of syscalls. As far as
> > security goes, the old adage of "less is more" applies.
>
> I can sort of see this argument, but *only* if the QEMU process is being
> run under a dedicated, fully unprivileged (from a DAC pov) user, completely
> separate from anything else on the system.
Or, of course, for a QEMU already confined by SELinux.
> If QEMU were being run as root, then even with seccomp, it could trivially
> just overwrite some binary in /bin, update /proc/core-pattern to point to
> this binary, and then crash itself. Now that core handling binary will
> execute without any of the seccomp filters applied.
>
> Similarly if QEMU is being run in the user's desktop session, I'm sure there
> is some kind of similar attack possible by changing a config setting for the
> user's GNOME/KDE session, and then waiting for GNOME/KDE to execute the script
> that QEMU just wrote out, once again bypassing seccomp.
Daniel
--
|: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org -o- http://virt-manager.org :|
|: http://autobuild.org -o- http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|
- Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in vl.c, (continued)
- Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in vl.c, Blue Swirl, 2012/06/15
- Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in vl.c, Paul Moore, 2012/06/15
- Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in vl.c, Blue Swirl, 2012/06/15
- Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in vl.c, Paul Moore, 2012/06/15
- Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in vl.c, Blue Swirl, 2012/06/16
- Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in vl.c, Corey Bryant, 2012/06/18
- Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in vl.c, Avi Kivity, 2012/06/19
- Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in vl.c, Blue Swirl, 2012/06/19
- Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in vl.c, Eric Blake, 2012/06/15
- Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in vl.c, Daniel P. Berrange, 2012/06/18
- Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in vl.c,
Daniel P. Berrange <=
- Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in vl.c, Paul Moore, 2012/06/18
- Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in vl.c, Daniel P. Berrange, 2012/06/18
- Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in vl.c, Paul Moore, 2012/06/18
- Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in vl.c, Eduardo Otubo, 2012/06/18
- Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in vl.c, Blue Swirl, 2012/06/18
- Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in vl.c, Corey Bryant, 2012/06/18
- Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in vl.c, Blue Swirl, 2012/06/18
- Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in vl.c, Daniel P. Berrange, 2012/06/19
- Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in vl.c, Blue Swirl, 2012/06/19
- Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in vl.c, Daniel P. Berrange, 2012/06/18