From: Kees Cook <keescook@chromium.org>
To: Michal Hocko <mhocko@kernel.org>
Cc: Christoph Lameter <cl@linux.com>,
Jonathan Corbet <corbet@lwn.net>,
Daniel Micay <danielmicay@gmail.com>,
David Windsor <dave@nullcore.net>,
Eric Biggers <ebiggers3@gmail.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Andrew Morton <akpm@linux-foundation.org>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Arnd Bergmann <arnd@arndb.de>, Andy Lutomirski <luto@kernel.org>,
Nicolas Pitre <nicolas.pitre@linaro.org>,
Tejun Heo <tj@kernel.org>, Daniel Mack <daniel@zonque.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Helge Deller <deller@gmx.de>, Rik van Riel <riel@redhat.com>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] mm: Allow slab_nomerge to be set at build time
Date: Fri, 23 Jun 2017 12:20:25 -0700 [thread overview]
Message-ID: <CAGXu5jJ8SD8hsMDfZ9qJHQbJ3iSTXTq81PpiG+kbnXwx=akDKg@mail.gmail.com> (raw)
In-Reply-To: <20170623140651.GD5314@dhcp22.suse.cz>
On Fri, Jun 23, 2017 at 7:06 AM, Michal Hocko <mhocko@kernel.org> wrote:
> On Tue 20-06-17 16:09:11, Kees Cook wrote:
>> Some hardened environments want to build kernels with slab_nomerge
>> already set (so that they do not depend on remembering to set the kernel
>> command line option). This is desired to reduce the risk of kernel heap
>> overflows being able to overwrite objects from merged caches and changes
>> the requirements for cache layout control, increasing the difficulty of
>> these attacks. By keeping caches unmerged, these kinds of exploits can
>> usually only damage objects in the same cache (though the risk to metadata
>> exploitation is unchanged).
>
> Do we really want to have a dedicated config for each hardening specific
> kernel command line? I believe we have quite a lot of config options
> already. Can we rather have a CONFIG_HARDENED_CMD_OPIONS and cover all
> those defauls there instead?
There's not been a lot of success with grouped Kconfigs in the past
(e.g. CONFIG_EXPERIMENTAL), but one thing that has been suggested is a
defconfig-like make target that would collect all the things together.
I haven't had time for that, but that would let us group the various
configs.
Additionally, using something like CONFIG_CMDLINE seems a little clunky to me.
-Kees
--
Kees Cook
Pixel Security
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next prev parent reply other threads:[~2017-06-23 19:20 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-20 23:09 [PATCH v2] mm: Allow slab_nomerge to be set at build time Kees Cook
2017-06-20 23:16 ` Randy Dunlap
2017-06-20 23:29 ` Kees Cook
2017-06-21 0:09 ` Randy Dunlap
2017-06-23 14:06 ` Michal Hocko
2017-06-23 19:20 ` Kees Cook [this message]
2017-06-26 9:00 ` Michal Hocko
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