linux-kernel - Re: [RFC PATCH] x86: Filter MSR writes from luserspace

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Message-ID: <20191127070836.GA94748@gmail.com>
Date:   Wed, 27 Nov 2019 08:08:36 +0100
From:   Ingo Molnar <mingo@...nel.org>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Andi Kleen <ak@...ux.intel.com>, x86-ml <x86@...nel.org>,
        lkml <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] x86: Filter MSR writes from luserspace

* Borislav Petkov <bp@...en8.de> wrote:

> On Tue, Nov 26, 2019 at 12:50:28PM -0800, Andi Kleen wrote:
> > You'll almost certainly violate Linus' golden rule of application
> > compatibility and the whole thing will be reverted in the end.

This objection is bogus, the ABI isn't broken, since this is basically a 
tweak of the default security model, by pushing questionable MSR 
modifications to a module or boot parameter. Those who know what they are 
doing can still do it.

The goal would be to make sure via a whitelist that end user distros 
won't have to set this parameter to permissive again, of course.

Thanks,

	Ingo