Re: [Gnu-arch-users] Re: arch roadmap 1 (and "what's tom up to")

[Marcus Sundman]

> The VM-level stuff we're talking about is just the idea of building in
> additional protection at the VM-level in a form that resembled
> privilege levels on a real CPU --- just a flag that certain primitives
> can check to decide between running normally and signalling an error.

If you want a good base for different kinds of security I think the only 
solution (currently known to mankind) is to support capability-based 
security. You can build any kind of security system on top of capabilities, 
but you can't build capabilities on top of inherently insecure systems such 
as ACLs. (Capability-based security requires support for "unforgeable" 
pointers (or similar), though, which means that programs can't see all code 
as writable data.)


- Marcus Sundman