Re: Combining Hurd and Qubes OS for security reasons? Possible?

On Wed, Dec 23, 2015 at 4:41 PM, Richard Braun <[email protected]> wrote:

> On Wed, Dec 23, 2015 at 11:56:23AM +0100, David Renz wrote:
> > You can under no circumstances get a secure system running on one or
> > multiple "system(s) of its/their own", because - as you have said it very
> > precisely - you have no control over this.
>
> That's not what I said. First, you don't run a secure system "on one or
> multiple systems of their own". You run one system among multiple ones.
>

But the important thing about this is: Those other systems have access to
your 'main system', as you also wrote in your last line - I don't believe
that a protection would be possible, too.


> Then, that system must have control over memory access because that's
> where the data is and that's what you want to protect. Finally, you
> need hardware that can actually restrict memory access from devices that
> are external from the point of view of that main system and physical
> memory.
>
> After reviewing SMM a bit more, it seems to be an x86 processor operating
> mode, giving access to normally inaccessible resources, hidden from the
> operating system, which means firmwares using that mode actually run on
> the main processor, and are subject to neither IOMMU nor MMU restrictions.
>
> If I'm right, it seems you just can't protect an x86 system from firmware
> interference.
>

That's why I often asked myself why not trying approaches based on other
hardware architectures - RaspberryPi might be worthy to look at for that
purpose.


>
> --
> Richard Braun
>