Re: [PATCH v2] x86/mm: warn on W+x mappings

From	Josh Triplett <josh@joshtriplett.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2] x86/mm: warn on W+x mappings
Date	2015-10-14 18:50 +0200
Message-ID	<qjxpv-4ki-3@gated-at.bofh.it> (permalink)
References	(4 earlier) <qgCF5-20n-31@gated-at.bofh.it> <qiJCq-64x-1@gated-at.bofh.it> <qiM7h-1nR-31@gated-at.bofh.it> <qiMJZ-29w-25@gated-at.bofh.it> <qjwa6-2yi-19@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Wed, Oct 14, 2015 at 05:19:40PM +0200, Ingo Molnar wrote:
> 
> * Josh Triplett <josh@joshtriplett.org> wrote:
> 
> > On Mon, Oct 12, 2015 at 04:17:54PM +0200, Ingo Molnar wrote:
> > > * Matt Fleming <matt@codeblueprint.co.uk> wrote:
> > > > On Mon, 12 Oct, at 02:49:36PM, Ingo Molnar wrote:
> > > > > So why not unmap them after bootup? Is there any reason to call into EFI code 
> > > > > while the system is up and running?
> > > > 
> > > > That's where the runtime services code lives. So if you want things like EFI 
> > > > variables (used by the distro installer, among other things) you need to map the 
> > > > runtime regions.
> > > 
> > > So EFI variables could be queried during bootup and saved on the Linux side.
> > 
> > That wouldn't support writing to EFI variables.  Or using the EFI
> > capsule update system to update firmware.
> 
> Well, if we know the location of those pages then we could map those 'rw-' - while 
> the rest would be mapped 'r-x'.

We have no way to do so in the absence of the additional code/data
separation information provided by more recent firmware.

- Josh Triplett
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Re: [PATCH v2] x86/mm: warn on W+x mappings Ingo Molnar <mingo@kernel.org> - 2015-10-06 09:40 +0200
  Re: [PATCH v2] x86/mm: warn on W+x mappings Stephen Smalley <sds@tycho.nsa.gov> - 2015-10-06 17:50 +0200
    Re: [PATCH v2] x86/mm: warn on W+x mappings Borislav Petkov <bp@alien8.de> - 2015-10-12 13:40 +0200
      Re: [PATCH v2] x86/mm: warn on W+x mappings Matt Fleming <matt@codeblueprint.co.uk> - 2015-10-12 14:50 +0200
        Re: [PATCH v2] x86/mm: warn on W+x mappings Ingo Molnar <mingo@kernel.org> - 2015-10-12 14:50 +0200
          Re: [PATCH v2] x86/mm: warn on W+x mappings Matt Fleming <matt@codeblueprint.co.uk> - 2015-10-12 15:00 +0200
            Re: [PATCH v2] x86/mm: warn on W+x mappings Ingo Molnar <mingo@kernel.org> - 2015-10-12 16:20 +0200
              Re: [PATCH v2] x86/mm: warn on W+x mappings Matt Fleming <matt@codeblueprint.co.uk> - 2015-10-12 16:50 +0200
                Re: [PATCH v2] x86/mm: warn on W+x mappings Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2015-10-12 17:40 +0200
                Re: [PATCH v2] x86/mm: warn on W+x mappings Matt Fleming <matt@codeblueprint.co.uk> - 2015-10-12 18:00 +0200
                Re: [PATCH v2] x86/mm: warn on W+x mappings Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2015-10-12 18:50 +0200
                Re: [PATCH v2] x86/mm: warn on W+x mappings Ingo Molnar <mingo@kernel.org> - 2015-10-14 17:20 +0200
                Re: [PATCH v2] x86/mm: warn on W+x mappings Borislav Petkov <bp@alien8.de> - 2015-10-14 17:40 +0200
                Re: [PATCH v2] x86/mm: warn on W+x mappings Matt Fleming <matt@codeblueprint.co.uk> - 2015-10-15 12:20 +0200
                Re: [PATCH v2] x86/mm: warn on W+x mappings Borislav Petkov <bp@alien8.de> - 2015-10-15 12:40 +0200
                Re: [PATCH v2] x86/mm: warn on W+x mappings Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2015-10-16 03:50 +0200
                Re: [PATCH v2] x86/mm: warn on W+x mappings Andy Lutomirski <luto@amacapital.net> - 2015-10-14 17:40 +0200
                Re: [PATCH v2] x86/mm: warn on W+x mappings Matt Fleming <matt@codeblueprint.co.uk> - 2015-10-14 23:10 +0200
              Re: [PATCH v2] x86/mm: warn on W+x mappings Josh Triplett <josh@joshtriplett.org> - 2015-10-12 17:00 +0200
                Re: [PATCH v2] x86/mm: warn on W+x mappings Ingo Molnar <mingo@kernel.org> - 2015-10-14 17:30 +0200
                Re: [PATCH v2] x86/mm: warn on W+x mappings Josh Triplett <josh@joshtriplett.org> - 2015-10-14 18:50 +0200

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