linux-kernel - Re: [RFC] selftests/x86: Add test

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Date:   Fri, 5 Jan 2018 09:53:16 -0800
From:   Andy Lutomirski <luto@...nel.org>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Andy Lutomirski <luto@...nel.org>, X86 ML <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Kees Cook <keescook@...omium.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [RFC] selftests/x86: Add test_vsyscall

On Fri, Jan 5, 2018 at 4:33 AM, Borislav Petkov <bp@...en8.de> wrote:
> On Thu, Jan 04, 2018 at 09:38:37PM -0800, Andy Lutomirski wrote:
>> Also, I want to add vsyscall=emulate_noread that makes the vsyscall
>> page be --x.  And I want to add a per-process option to turn off
>> vsyscalls.
>
> What for?
>
> It sounds like a bunch of work for something which is deprecated
> anyway...
>

emulate_noread would avoid one exploit technique that Kees saw
somewhere.  And per-process disablement would let a system remain
compatible with old binaries without reducing security for newer
binaries.