linux-kernel - Re: [PATCH v2 0/6] mm, x86/vdso: Special IO mapping improvements

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Date:	Wed, 23 Dec 2015 15:56:52 -0800
From:	Andy Lutomirski <luto@...capital.net>
To:	Andy Lutomirski <luto@...nel.org>, Oleg Nesterov <oleg@...hat.com>,
	Kees Cook <keescook@...omium.org>
Cc:	X86 ML <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Borislav Petkov <bp@...en8.de>
Subject: Re: [PATCH v2 0/6] mm, x86/vdso: Special IO mapping improvements

Hi Oleg and Kees-

I meant to cc you on this in the first place, but I failed.  If you
have a few minutes, want to take a peek at these and see if you can
poke any holes in them?  I'm reasonably confident that they're a
considerable improvement over the old state of affairs, but they might
still not be perfect.

Let me know if you want me to email out a fresh copy.  This series
applies to tip:x86/asm.

--Andy

On Mon, Dec 14, 2015 at 10:31 AM, Andy Lutomirski <luto@...nel.org> wrote:
> This applies on top of the earlier vdso pvclock series I sent out.
> Once that lands in -tip, this will apply to -tip.
>
> This series cleans up the hack that is our vvar mapping.  We currently
> initialize the vvar mapping as a special mapping vma backed by nothing
> whatsoever and then we abuse remap_pfn_range to populate it.
>
> This cheats the mm core, probably breaks under various evil madvise
> workloads, and prevents handling faults in more interesting ways.
>
> To clean it up, this series:
>
>  - Adds a special mapping .fault operation
>  - Adds a vm_insert_pfn_prot helper
>  - Uses the new .fault infrastructure in x86's vdso and vvar mappings
>  - Hardens the HPET mapping, mitigating an HW attack surface that bothers me
>
> akpm, can you ack patck 1?
>
> Changes from v1:
>  - Lots of changelog clarification requested by akpm
>  - Minor tweaks to style and comments in the first two patches
>
> Andy Lutomirski (6):
>   mm: Add a vm_special_mapping .fault method
>   mm: Add vm_insert_pfn_prot
>   x86/vdso: Track each mm's loaded vdso image as well as its base
>   x86,vdso: Use .fault for the vdso text mapping
>   x86,vdso: Use .fault instead of remap_pfn_range for the vvar mapping
>   x86/vdso: Disallow vvar access to vclock IO for never-used vclocks
>
>  arch/x86/entry/vdso/vdso2c.h            |   7 --
>  arch/x86/entry/vdso/vma.c               | 124 ++++++++++++++++++++------------
>  arch/x86/entry/vsyscall/vsyscall_gtod.c |   9 ++-
>  arch/x86/include/asm/clocksource.h      |   9 +--
>  arch/x86/include/asm/mmu.h              |   3 +-
>  arch/x86/include/asm/vdso.h             |   3 -
>  arch/x86/include/asm/vgtod.h            |   6 ++
>  include/linux/mm.h                      |   2 +
>  include/linux/mm_types.h                |  22 +++++-
>  mm/memory.c                             |  25 ++++++-
>  mm/mmap.c                               |  13 ++--
>  11 files changed, 151 insertions(+), 72 deletions(-)
>
> --
> 2.5.0
>



-- 
Andy Lutomirski
AMA Capital Management, LLC
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