Openwall GNU/*/Linux - a small security-enhanced Linux distro for servers
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Mon, 6 Aug 2018 11:49:34 -0700
From: Kees Cook <keescook@...omium.org>
To: Robin Murphy <robin.murphy@....com>
Cc: Ard Biesheuvel <ard.biesheuvel@...aro.org>, 
	Kernel Hardening <kernel-hardening@...ts.openwall.com>, Mark Rutland <mark.rutland@....com>, 
	Catalin Marinas <catalin.marinas@....com>, Will Deacon <will.deacon@....com>, 
	Christoffer Dall <christoffer.dall@....com>, 
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>, 
	Laura Abbott <labbott@...oraproject.org>, Julien Thierry <julien.thierry@....com>
Subject: Re: [RFC/PoC PATCH 0/3] arm64: basic ROP mitigation

On Mon, Aug 6, 2018 at 10:45 AM, Robin Murphy <robin.murphy@....com> wrote:
> I guess what I'm getting at is that if the protection mechanism is "always
> return with SP outside TTBR1", there seems little point in going through the
> motions if SP in TTBR0 could still be valid and allow an attack to succeed
> anyway; this is basically just me working through a justification for saying
> the proposed scheme needs "depends on ARM64_PAN || ARM64_SW_TTBR0_PAN",
> making it that much uglier for v8.0 CPUs...

I think anyone with v8.0 CPUs interested in this mitigation would also
very much want PAN emulation. If a "depends on" isn't desired, what
about "imply" in the Kconfig?

-Kees

-- 
Kees Cook
Pixel Security

Powered by blists - more mailing lists

Your e-mail address:

Powered by Openwall GNU/*/Linux - Powered by OpenVZ