Re: [Qemu-devel] [RFC] [PATCHv2 2/2] Adding basic calls to libseccomp in vl.c

[Paul Moore]

On Monday, June 18, 2012 09:31:03 AM 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.

Agreed ... and considering at least one major distribution takes this approach 
it seems like reasonable functionality to me.  Confining QEMU, either through 
DAC and/or MAC, when faced with potentially malicious guests is just good 
sense.

-- 
paul moore
security and virtualization @ redhat