linux-kernel - Re: [PATCH 0/6] kexec: A new system call to allow in kernel loading

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Date:	Fri, 22 Nov 2013 09:55:15 +0900
From:	HATAYAMA Daisuke <d.hatayama@...fujitsu.com>
To:	Vivek Goyal <vgoyal@...hat.com>
CC:	linux-kernel@...r.kernel.org, kexec@...ts.infradead.org,
	mjg59@...f.ucam.org, greg@...ah.com, ebiederm@...ssion.com,
	hpa@...or.com
Subject: Re: [PATCH 0/6] kexec: A new system call to allow in kernel loading

(2013/11/21 2:50), Vivek Goyal wrote:
> Current proposed secureboot implementation disables kexec/kdump because
> it can allow unsigned kernel to run on a secureboot platform. Intial
> idea was to sign /sbin/kexec binary and let that binary do the kernel
> signature verification. I had posted RFC patches for this apparoach
> here.
>
> https://lkml.org/lkml/2013/9/10/560
>
> Later we had discussion at Plumbers and most of the people thought
> that signing and trusting /sbin/kexec is becoming complex. So a
> better idea might be let kernel do the signature verification of
> new kernel being loaded. This calls for implementing a new system call
> and moving lot of user space code in kernel.
>
> kexec_load() system call allows loading a kexec/kdump kernel and jump
> to that kernel at right time. Though a lot of processing is done in
> user space which prepares a list of segments/buffers to be loaded and
> kexec_load() works on that list of segments. It does not know what's
> contained in those segments.
>
> Now a new system call kexec_file_load() is implemented which takes
> kernel fd and initrd fd as parameters. Now kernel should be able
> to verify signature of newly loaded kernel.
>
> This is an early RFC patchset. I have not done signature handling
> part yet. This is more of a minimal patch to show how new system
> call and functionality will look like. Right now it can only handle
> bzImage with 64bit entry point on x86_64. No EFI, no x86_32  or any
> other architecture. Rest of the things can be added slowly as need
> arises. In first iteration, I have tried to address most common use case
> for us.
>
> Any feedback is welcome.
>

So, ultimately on this design direction, user-land kexec command someday
will no longer be used at all? Or is there any feature you will keep in
user-land side?

I think it big change if one component in kdump will disappear.

-- 
Thanks.
HATAYAMA, Daisuke

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