Re: [PATCH v2] kexec: add sysctl to disable kexec

Kees Cook
2013-12-10T01:06:13Z

On Mon, Dec 9, 2013 at 4:34 PM, H. Peter Anvin <hpa@zytor.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@chromium.org>
>> Acked-by: Rik van Riel <riel@redhat.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