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SubjectRe: [Security] [PATCH] proc: avoid information leaks to non-privileged processes

* Matt Mackall <mpm@selenic.com> wrote:

> On Wed, May 06, 2009 at 12:30:34PM +0200, Ingo Molnar wrote:
> > (Also, obviously "only" covering 95% of the Linux systems has its
> > use as well. Most other architectures have their own cycle counters
> > as well.)
>
> X86 might be 95% of desktop. But it's a small fraction of Linux
> systems once you count cell phones, video players, TVs, cameras,
> GPS devices, cars, routers, etc. almost none of which are
> x86-based. In fact, just Linux cell phones (with about an 8% share
> of a 1.2billion devices per year market) dwarf Linux desktops
> (maybe 5% of a 200m/y market).

Firstly, the cycle counter is just one out of several layers there.
So it's a hyperbole to suggest that i'm somehow not caring about
architectures that dont have a cycle counter. I'm simply making use
of a cheaply accessed and fast-changing variable on hw that has it.

Also, are those systems really going to be attacked locally,
brute-forcing a PRNG? Servers and desktops are the more likely
targets. They both have the necessary computing power to run
statistical analysis locally fast enough and have an actual value to
be attacked.

And, even if we ignored those factors, ad argumendo, you would still
be wrong IMHO: what matters really in this context isnt even any
artificial 'share' metric - but the people willing to improve and
fix the upstream kernel, and the reasons why they do that, and the
platforms they use.

And amongst our contributors and testers, willing to run and improve
the latest upstream kernel, x86 has a larger than 95% share. Look at
kerneloops.org stats. Or bugzilla. Or lkml.

If embedded matters that much, make it show up as a real factor on
those upstream forums. Lets call this Ingo's Law: if something
doesnt improve the upstream kernel, directly or indirectly, it does
not exist ;-)

Ingo


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