Re: New user getting started questions

Thomas Leonard
2021-03-13T12:52:56Z

On Tue, 9 Mar 2021 at 16:26, Alyssa Ross <hi@alyssa.is> wrote:
>
> Hi Thomas!
>
> Thanks for keeping us updated. It's really great to have all this
> written up to read, even though I'm only getting to it a month and a
> half later.
>
> On Wed, Jan 27, 2021 at 05:31:08PM +0000, Thomas Leonard wrote:
[...]
> > Once this is working more smoothly, I guess the next issues will be
> > setting up some kind of secure window manager on the host (e.g.
> > labelling windows with the VM they come from, not allowing
> > screenshots, etc). Would also be good to get sound forwarding working
> > somehow (Qubes routes pulseaudio to all the VMs and gives you a mixer
> > to control the levels for each, but I don't know how that worked). It
> > also needs some kind of VM manager to keep track of which VMs are
> > running. And some kind of IPC system like qrexec would be useful. Do
> > you have thoughts or plans about how to do any of this?
>
> The window manager is a part of this whole thing that makes me very
> nervous. A secure window manager is very important for Wayland, and I'm
> not sure how much I trust any of the existing ones to get it right. But
> with Wayfire I'm hoping it'll at least be easy enough to implement stuff
> like tagged/coloured windows for the proof of concept (since the
> plugin API and stuff is Wayfire's niche), and I'm hoping at some point
> somebody comes up with a security-focused Wayland window manager we can
> switch to -- I'd love a Rust one, and there's work going on in that
> area[1].

For the short-term, it would be fairly easy to make a slight change to
the wayland-virtwl-proxy[*] so that a version of it could run on the
host. Unlike the guest one, which has to copy frames and deal with
virtwl, this would just pass FDs through. And instead of connecting to
/dev/wl0, it would just connect to the host compositor socket. It
would then block access to screenshots (since it doesn't proxy that),
and would add the VM's name to each window's title.

Eventually I'd like to turn it into a full compositor, but I'm going
to be busy for the next 6 months at least.

> Not sure about IPC yet, but I recently read an article about PipeWire[2],
> and that's been making me think a bit about audio. With PipeWire, they
> seem to have cared about security from the start:

Thanks for the link. I hadn't realised PulseAudio was in such a bad state!

> > To avoid the PulseAudio sandboxing limitations, security was
> > baked-in: a per-client permissions bitfield is attached to every
> > PipeWire node — where one or more SPA nodes are wrapped. This
> > security-aware design allowed easy and safe integration with Flatpak
> > portals; the sandboxed-application permissions interface now promoted
> > to a freedesktop XDG standard.
>
> And it gets better! In particular, this sounds very promising:
>
> > a native fully asynchronous protocol that was inspired by Wayland —
> > without the XML serialization part — was implemented over Unix-domain
> > sockets. Taymans wanted a protocol that is simple and hard-realtime
> > safe.
>
> It goes on to say they use this for sending file descriptors and stuff.
> The similarity to Wayland is very exciting, because it means we might
> just be able to run PipeWire over the existing virtio_wl infrastructure
> very efficiently.

Yes. I wonder why they didn't just use Wayland directly. Removing the
XML schema files (I assume that's what they mean) doesn't seem like an
improvement. That's what makes it easy to use Wayland from safer
languages than C!

[*] https://github.com/talex5/wayland-virtwl-proxy

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