Re: [Qemu-devel] [RFC] [PATCH 0/2] Sandboxing Qemu guests with Libseccomp

[Stefano Stabellini]

On Tue, 8 May 2012, Daniel P. Berrange wrote:
> On Fri, May 04, 2012 at 04:08:36PM -0300, Eduardo Otubo wrote:
> > Hello all,
> > 
> > This is the first effort to sandboxing Qemu guests using Libseccomp[0]. The
> > patches that follows are pretty simple and straightforward. I added the 
> > correct
> > options and checks to the configure script and the basic calls to 
> > libseccomp in
> > the main loop at vl.c. Details of each one are in the emails of the patch 
> > set.
> > 
> > This support limits the system call footprint of the entire QEMU process to 
> > a
> > limited set of syscalls, those that we know QEMU uses.  The idea is to limit
> > the allowable syscalls, therefore limiting the impact that an attacked guest
> > could have on the host system.
> 
> What functionality has been lost by applying this seccomp filter ? I've not
> looked closely at the code, but it appears as if this blocks pretty much
> any kind of runtime device changes. ie no hotplug of any kind will work ?

Right, I was wondering the same thing: open is not on the list so adding
a new disk shouldn't be possible.

Regarding Xen, most of the hypercalls go through xc_* calls that are
ioctls on the privcmd device. Is it possible to add ioctl to the list?