Re: [Syllable-kernel] Syllable security and "trusted computing"

[Mark W. <mar...@cl...>]

Hi Kip, didn't expect to see you here ;-)

> > First, every UNIX OS as well as Windows uses only two of the four
> > "rings" of protection on x86.  The kernel and all modules run in Ring 0
> > and all user programs run in Ring 3.  Ring 0 can bypass all protections.
> >   What's interesting about the special hardware support that is being
> > added for "Palladium" (what Intel calls "LaGrande Technology", or LT),
> > is that they've essentially had to add a new "Ring -1" that is more
> > privileged than the layer at which the normal operating system runs, in
> > order to be able to assure the privacy and security that Windows itself
> > is apparently not able to provide.  This is stupid:  if we have Rings 1
>
> No it isn't, it is necessary if they are to support running Windows
> _unmodified_ on top of a hypervisor. See VT-x.

VT-x introduces "root mode" and "non-root mode", which is orthogonal to the 
ring you're running in (although root mode can only be entered and left in 
certain restricted ways).  Root mode & ring 0 is where a hypervisor would 
run, non-root mode & rings 0-3 would contain guest OSs.

One thing which I'm curious about is exactly what form "Ring -1" in LT will 
actually take.  Both AMD's and Intel's security extensions are dependent on 
their virtualisation extentions because they use similar mechanisms.  I guess 
it may be that "ring -1" == "root mode ring 0".  Speculation on my part...

Are there any specs available for LT?  I haven't seen any, the deadline for LT 
seems to have moved back relative to what I was expecting.

Cheers,
Mark