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

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Message-ID: <52A66190.9060907@zytor.com>
Date:	Mon, 09 Dec 2013 16:34:24 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Kees Cook <keescook@...omium.org>, linux-kernel@...r.kernel.org
CC:	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,
	kexec@...ts.infradead.org
Subject: Re: [PATCH v2] kexec: add sysctl to disable kexec

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?

	-hpa


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