Re: [Qemu-devel] [RFC] host and guest kernel trace merging

[Paolo Bonzini <pbonzini@redhat.com>]

On 07/03/2016 17:26, Steven Rostedt wrote:
> > > How's the connection set up. That is, how does it know the commands are
> > > coming from the host? And how does it know that the commands from the
> > > host is from a trusted source? If the host is compromised, is there
> > > anything keeping an intruder from controlling the guest?  
> > 
> > qemu-guest-agent uses a virtio channel, so only the host can be driving
> > that channel.  But how can a guest know that it trusts the host? It
> > can't.  A compromised host implicitly compromises all guests, and that's
> > always been the case.  At least qemu-guest-agent doesn't make the window
> > any larger.
>
> I should have been a bit more clear about what I meant by "host is
> compromised". I should have asked, what about untrusted tasks on the
> host. Is the channel protected where only admin users can access it?

The other side of the channel is typically a socket or a pty, so it's
protected by file permissions, SELinux, and the like.

Paolo