linux-kernel - Re: [PATCH v2] kexec: add sysctl to disable kexec

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 9 Dec 2013 17:06:10 -0800
From:	Kees Cook <keescook@...omium.org>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Rik van Riel <riel@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Matthew Garrett <matthew.garrett@...ula.com>,
	Vivek Goyal <vgoyal@...hat.com>, Rob Landley <rob@...dley.net>,
	Eric Biederman <ebiederm@...ssion.com>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Mel Gorman <mgorman@...e.de>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	kexec@...ts.infradead.org
Subject: Re: [PATCH v2] kexec: add sysctl to disable kexec

On Mon, Dec 9, 2013 at 4:34 PM, H. Peter Anvin <hpa@...or.com> wrote:
> On 12/09/2013 04:16 PM, Kees Cook wrote:
>> For general-purpose (i.e. distro) kernel builds it makes sense to build with
>> CONFIG_KEXEC to allow end users to choose what kind of things they want to do
>> with kexec. However, in the face of trying to lock down a system with such
>> a kernel, there needs to be a way to disable kexec (much like module loading
>> can be disabled). Without this, it is too easy for the root user to modify
>> kernel memory even when CONFIG_STRICT_DEVMEM and modules_disabled are set.
>>
>> Signed-off-by: Kees Cook <keescook@...omium.org>
>> Acked-by: Rik van Riel <riel@...hat.com>
>
> So the logic is to load a crashkernel and then lock down the machine
> before services, networking etc. are enabled?

Right, or to just turn it off at boot time if kexec will not be used at all.

-Kees

-- 
Kees Cook
Chrome OS Security
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/