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Date: Fri, 15 Jul 2016 12:14:23 -0700
From: Kees Cook <keescook@...omium.org>
To: "kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>
Cc: Balbir Singh <bsingharora@...il.com>, LKML <linux-kernel@...r.kernel.org>, 
	Rik van Riel <riel@...hat.com>, Casey Schaufler <casey@...aufler-ca.com>, 
	PaX Team <pageexec@...email.hu>, Brad Spengler <spender@...ecurity.net>, 
	Russell King <linux@...linux.org.uk>, Catalin Marinas <catalin.marinas@....com>, 
	Will Deacon <will.deacon@....com>, Ard Biesheuvel <ard.biesheuvel@...aro.org>, 
	Benjamin Herrenschmidt <benh@...nel.crashing.org>, Michael Ellerman <mpe@...erman.id.au>, 
	Tony Luck <tony.luck@...el.com>, Fenghua Yu <fenghua.yu@...el.com>, 
	"David S. Miller" <davem@...emloft.net>, "x86@...nel.org" <x86@...nel.org>, Christoph Lameter <cl@...ux.com>, 
	Pekka Enberg <penberg@...nel.org>, David Rientjes <rientjes@...gle.com>, 
	Joonsoo Kim <iamjoonsoo.kim@....com>, Andrew Morton <akpm@...ux-foundation.org>, 
	Andy Lutomirski <luto@...nel.org>, Borislav Petkov <bp@...e.de>, Mathias Krause <minipli@...glemail.com>, 
	Jan Kara <jack@...e.cz>, Vitaly Wool <vitalywool@...il.com>, 
	Andrea Arcangeli <aarcange@...hat.com>, Dmitry Vyukov <dvyukov@...gle.com>, 
	Laura Abbott <labbott@...oraproject.org>, 
	"linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, linux-ia64@...r.kernel.org, 
	"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>, sparclinux <sparclinux@...r.kernel.org>, 
	linux-arch <linux-arch@...r.kernel.org>, Linux-MM <linux-mm@...ck.org>
Subject: Re: Re: [PATCH v2 02/11] mm: Hardened usercopy

On Fri, Jul 15, 2016 at 12:00 PM, Daniel Micay <danielmicay@...il.com> wrote:
>> This could be a BUG, but I'd rather not panic the entire kernel.
>
> It seems unlikely that it will panic without panic_on_oops and that's
> an explicit opt-in to taking down the system on kernel logic errors
> exactly like this. In grsecurity, it calls the kernel exploit handling
> logic (panic if root, otherwise kill all process of that user and ban
> them until reboot) but that same logic is also called for BUG via oops
> handling so there's only really a distinction with panic_on_oops=1.
>
> Does it make sense to be less fatal for a fatal assertion that's more
> likely to be security-related? Maybe you're worried about having some
> false positives for the whitelisting portion, but I don't think those
> will lurk around very long with the way this works.

I'd like it to dump stack and be fatal to the process involved, but
yeah, I guess BUG() would work. Creating an infrastructure for
handling security-related Oopses can be done separately from this (and
I'd like to see that added, since it's a nice bit of configurable
reactivity to possible attacks).

-Kees

-- 
Kees Cook
Chrome OS & Brillo Security

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