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Re: [Qemu-devel] [PATCH v2 0/2] Add dbus-vmstate
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH v2 0/2] Add dbus-vmstate |
Date: |
Fri, 23 Aug 2019 15:09:48 +0100 |
User-agent: |
Mutt/1.12.1 (2019-06-15) |
* Marc-André Lureau (address@hidden) wrote:
> Hi
>
> On Fri, Aug 23, 2019 at 5:00 PM Dr. David Alan Gilbert
> <address@hidden> wrote:
> >
> > * Daniel P. Berrangé (address@hidden) wrote:
> >
> > <snip>
> >
> > > This means QEMU still has to iterate over every single client
> > > on the bus to identify them. If you're doing that, there's
> > > no point in owning a well known service at all. Just iterate
> > > over the unique bus names and look for the exported object
> > > path /org/qemu/VMState
> > >
> >
> > Not knowing anything about DBus security, I want to ask how do
> > we handle security here?
>
> First of all, we are talking about cooperative processes, and having a
> specific bus for each qemu instance. So some amount of security/trust
> is already assumed.
Some but we need to keep it as limited as possible; for example two
reasons for having separate processes both come down to security:
a) vtpm - however screwy the qemu is, you can never get to the keys in
the vtpm
b) virtio-gpu, loads of complex GPU code that can't break the main
qemu process.
> But if necessary, dbus can enforce policies on who is allowed to own a
> name, or to send/receive message from. As far as I know, this is
> mostly user/group policies.
>
> But there is also SELinux checks to send_msg and acquire_svc (see
> dbus-daemon(1))
But how does something like SELinux interact with a private dbus
rather than the system dbus?
> >
> > I want to know that the external device that's giving me migration data
> > is the device I think I'm speaking to, not one of the other devices;
>
> DBus is not the problem nor the solution here.
Well, if the migration data was squirting down the existing vhost-user
channel then there would be no risk here; so the use of dbus is creating
the problem.
> But what defines that device-service strong relationship? Can you
> generalize it? I don't think so.
>
> What DBus can guarantee is that the unique-id you are talking to is
> always the same connection (thus the same process).
>
> > I also dont want different devices chatting to each other over dbus
> > unless we're very careful.
>
> That's a bus policy job.
OK, as long as you somehow set it up.
Dave
> >
> > Dave
> >
> > > Regards,
> > > Daniel
> > > --
> > > |: https://berrange.com -o-
> > > https://www.flickr.com/photos/dberrange :|
> > > |: https://libvirt.org -o-
> > > https://fstop138.berrange.com :|
> > > |: https://entangle-photo.org -o-
> > > https://www.instagram.com/dberrange :|
> > --
> > Dr. David Alan Gilbert / address@hidden / Manchester, UK
> >
>
>
> --
> Marc-André Lureau
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- Re: [Qemu-devel] [PATCH v2 2/2] Add dbus-vmstate object, (continued)
Re: [Qemu-devel] [PATCH v2 0/2] Add dbus-vmstate, Daniel P . Berrangé, 2019/08/23
- Re: [Qemu-devel] [PATCH v2 0/2] Add dbus-vmstate, Marc-André Lureau, 2019/08/23
- Re: [Qemu-devel] [PATCH v2 0/2] Add dbus-vmstate, Daniel P . Berrangé, 2019/08/23
- Re: [Qemu-devel] [PATCH v2 0/2] Add dbus-vmstate, Marc-André Lureau, 2019/08/23
- Re: [Qemu-devel] [PATCH v2 0/2] Add dbus-vmstate, Dr. David Alan Gilbert, 2019/08/23
- Re: [Qemu-devel] [PATCH v2 0/2] Add dbus-vmstate, Marc-André Lureau, 2019/08/23
- Re: [Qemu-devel] [PATCH v2 0/2] Add dbus-vmstate, Daniel P . Berrangé, 2019/08/23
- Re: [Qemu-devel] [PATCH v2 0/2] Add dbus-vmstate,
Dr. David Alan Gilbert <=
- Re: [Qemu-devel] [PATCH v2 0/2] Add dbus-vmstate, Daniel P . Berrangé, 2019/08/23
- Re: [Qemu-devel] [PATCH v2 0/2] Add dbus-vmstate, Dr. David Alan Gilbert, 2019/08/23
- Re: [Qemu-devel] [PATCH v2 0/2] Add dbus-vmstate, Daniel P . Berrangé, 2019/08/23
- Re: [Qemu-devel] [PATCH v2 0/2] Add dbus-vmstate, Dr. David Alan Gilbert, 2019/08/23
- Re: [Qemu-devel] [PATCH v2 0/2] Add dbus-vmstate, Daniel P . Berrangé, 2019/08/23
- Re: [Qemu-devel] [PATCH v2 0/2] Add dbus-vmstate, Dr. David Alan Gilbert, 2019/08/23
- Re: [Qemu-devel] [PATCH v2 0/2] Add dbus-vmstate, Daniel P . Berrangé, 2019/08/23
- Re: [Qemu-devel] [PATCH v2 0/2] Add dbus-vmstate, Dr. David Alan Gilbert, 2019/08/23