Re: PCI arbiter memory mapping

[Sergey Bugaev]

On Tue, Aug 17, 2021 at 9:14 PM Joan Lledó <jlledom@mailfence.com> wrote:
> > The underlying question is getting the memory object of a given memory
> > range, like vm_region does.
>
> Yes, I see that could be useful. Is vm_region not workig for proxies?
>
>  > We need to be careful since we don't want any process to be able to
>  > get the memory object of any other process
>
> Is that not being checked yet? can I call vm_region to get another
> task's memory object now?

It doesn't matter whether it's another task or not, or whether it's a
proxy or not (in fact it will never be a proxy, but that doesn't
matter): you can no longer get the underlying memory object with
vm_region () — for, uh, obvious security reasons. It was a gnumach
extension anyway — vanilla Mach doesn't support that.

(Well in fact what actually changed is that gnumach at some point
allowed the use of "memory object name ports" in vm_map (), and now
once again doesn't. It never allowed you to get the actual memory
object.)

Sergey