* Marc-André Lureau (marcandre.lur...@gmail.com) wrote: > Hi > > On Fri, Aug 23, 2019 at 5:00 PM Dr. David Alan Gilbert > <dgilb...@redhat.com> wrote: > > > > * Daniel P. Berrangé (berra...@redhat.com) 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 / dgilb...@redhat.com / Manchester, UK > > > > > -- > Marc-André Lureau -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
