Re: [Ksummit-discuss] late self-nomination

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Aug 02, 2016 at 10:28:43AM -0700, Andy Lutomirski wrote:
> On Tue, Aug 2, 2016 at 10:23 AM, Michael S. Tsirkin <mst@redhat.com> wrote:
> > Hi folks!
> >
> > Likely too late, but oh well.
> > I would like to self-nominate for kernel summit this year.
> >
> > I am the maintainer of the virtio subsystem, and within KVM, of the PC
> > and PCI subsystems.  Intelnally within Red Hat I'm a tech lead for the
> > team handling the networking for VMs.
> >
> > I would like to participate in self-hardening to see whether
> > hypervisor extensions (like e.g. kernel guard technology)
> > can benefit that project,
> 
> This isn't quite on-topic, but I suggested something that I think
> would be useful last year (possibly off-list -- I don't remember):
> 
> On x86 with VMX, the EPT page tables have separate R, W, and X bits.
> If a hypervisor were to limit the guest physical address space to the
> lower half (high bit always clear) and then alias all of it with the
> high guest physical address bit set and R clear, then the guest could
> use the high physical address bit as an effective R bit.  That would
> allow PROT_WRITE, PROT_EXEC, and PROT_WRITE|PROT_EXEC mappings to work
> without granting read access.
> 
> Doing this would provide some protection against attacks that use a
> wild read to scan for code or data structures at otherwise
> unpredictable addresses or to blindly search for ROP gadgets.

Thanks - I expect we'll discuss this topic with other kvm folks quite a
bit on the kvm forum end of August, as well.

-- 
MST