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Message-ID: <alpine.LSU.2.00.1210021733580.1343@eggly.anvils>
Date: Tue, 2 Oct 2012 17:43:20 -0700 (PDT)
From: Hugh Dickins <hughd@...gle.com>
To: Andrew Morton <akpm@...ux-foundation.org>
cc: Kees Cook <keescook@...omium.org>,
Ard Biesheuvel <ard.biesheuvel@...il.com>,
linux-kernel@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>,
Ingo Molnar <mingo@...nel.org>,
Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
James Morris <jmorris@...ei.org>,
Konstantin Khlebnikov <khlebnikov@...nvz.org>,
linux-mm@...ck.org
Subject: Re: [PATCH] hardening: add PROT_FINAL prot flag to mmap/mprotect
On Tue, 2 Oct 2012, Andrew Morton wrote:
> On Tue, 2 Oct 2012 15:10:56 -0700
> Kees Cook <keescook@...omium.org> wrote:
>
> > >> Has there been any more progress on this patch over-all?
> > >
> > > No progress.
> >
> > Al, Andrew, anyone? Thoughts on this?
> > (First email is https://lkml.org/lkml/2012/8/14/448)
>
> Wasn't cc'ed, missed it.
>
> The patch looks straightforward enough. Have the maintainers of the
> runtime linker (I guess that's glibc) provided any feedback on the
> proposal?
It looks reasonable to me too. I checked through VM_MAYflag handling
and don't expect surprises (a few places already turn off VM_MAYWRITE
in much the same way that this does, I hadn't realized).
I'm disappointed to find that our mmap() is lax about checking its
PROT and MAP args, so old kernels will accept PROT_FINAL but do
nothing with it. Luckily mprotect() is stricter, so that can be
used to check for whether it's supported.
The patch does need to be slightly extended though: alpha, mips,
parisc and xtensa have their own include/asm/mman.h, which does
not include asm-generic/mman-common.h at all.
Hugh
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