From: Michal Hocko <mhocko@kernel.org>
To: Kees Cook <keescook@chromium.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: Mon, 26 Jun 2017 11:00:55 +0200 [thread overview]
Message-ID: <20170626090054.GF11534@dhcp22.suse.cz> (raw)
In-Reply-To: <CAGXu5jJ8SD8hsMDfZ9qJHQbJ3iSTXTq81PpiG+kbnXwx=akDKg@mail.gmail.com>
On Fri 23-06-17 12:20:25, Kees Cook wrote:
> 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.
Which wouldn't reduce the number of config options, would it? I don't
know but is there any usecase when somebody wants to have hardened
kernel and still want to have different defaults than you are
suggesting?
--
Michal Hocko
SUSE Labs
prev parent reply other threads:[~2017-06-26 9:01 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
2017-06-26 9:00 ` Michal Hocko [this message]
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