Re: MSR support for x86

root (abszero@epix.net)
Fri, 28 Feb 1997 19:02:56 -7700 (EST)

Stephan Meyer wrote:
>
> On 28 Feb 1997, H. Peter Anvin wrote:
> > > This is an interesting suggestion :)
> > > If we implement this, it should be tightly secured since any user could
> > > mess around with the 2nd level cache. A possible application could be a
> > > CPU manager!
> > >
> >
> > I think letting any non-root user messing with the MSRs or anything
> > like that is asking for trouble in a big way. /dev/msr definitely
> > should be a root-only device!
> >
> > -hpa
>
> I'm not a security expert, but isn't it enough to set permissions to
> something like crw------- ?
>
> Stephan

I should think you would want it to be crw-r--r--, so that anybody can see
what they are running on. Perhaps the /dev/msr code should double check
that root is doing the write, so even if somebody can get past the VFS, they
still can't fry your CPU.

Also, what will this do on a SMP system? Just die, only set the first CPU,
set all of them?

--- James Mastros