linux-kernel - Re: [RFC PATCH 00/13][V3] kexec: A new system call to allow in kernel loading

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Message-ID: <20140612054203.GA3696@darkstar.nay.redhat.com>
Date:	Thu, 12 Jun 2014 13:42:03 +0800
From:	Dave Young <dyoung@...hat.com>
To:	Vivek Goyal <vgoyal@...hat.com>
Cc:	linux-kernel@...r.kernel.org, kexec@...ts.infradead.org,
	ebiederm@...ssion.com, hpa@...or.com, mjg59@...f.ucam.org,
	greg@...ah.com, bp@...en8.de, jkosina@...e.cz, chaowang@...hat.com,
	bhe@...hat.com, akpm@...ux-foundation.org
Subject: Re: [RFC PATCH 00/13][V3] kexec: A new system call to allow in
 kernel loading

On 06/03/14 at 09:06am, Vivek Goyal wrote:
> Hi,
> 
> This is V3 of the patchset. Previous versions were posted here.
> 
> V1: https://lkml.org/lkml/2013/11/20/540
> V2: https://lkml.org/lkml/2014/1/27/331
> 
> Changes since v2:
> 
> - Took care of most of the review comments from V2.
> - Added support for kexec/kdump on EFI systems.
> - Dropped support for loading ELF vmlinux.
> 
> This patch series is generated on top of 3.15.0-rc8. It also requires a
> two patch cleanup series which is sitting in -tip tree here.
> 
> https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git/log/?h=x86/boot
> 
> This patch series does not do kernel signature verification yet. I plan
> to post another patch series for that. Now bzImage is already signed
> with PKCS7 signature I plan to parse and verify those signatures.
> 
> Primary goal of this patchset is to prepare groundwork so that kernel
> image can be signed and signatures be verified during kexec load. This
> should help with two things.
> 
> - It should allow kexec/kdump on secureboot enabled machines.
> 
> - In general it can help even without secureboot. By being able to verify
>   kernel image signature in kexec, it should help with avoiding module
>   signing restrictions. Matthew Garret showed how to boot into a custom
>   kernel, modify first kernel's memory and then jump back to old kernel and
>   bypass any policy one wants to.
> 
> Any feedback is welcome.

Hi, Vivek

For efi ioremapping case, in 3.15 kernel efi runtime maps will not be saved
if efi=old_map is used. So you need detect this and fail the kexec file load.

Otherwise the patchset works for me.

Thanks
Dave
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