linux-kernel - Re: [PATCH 4/6] kexec: A new system call, kexec_file

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Message-ID: <87a9fvqfs4.fsf@xmission.com>
Date:	Fri, 20 Dec 2013 15:11:23 -0800
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Vivek Goyal <vgoyal@...hat.com>
Cc:	Torsten Duwe <duwe@....de>, Matthew Garrett <mjg59@...f.ucam.org>,
	Greg KH <greg@...ah.com>, linux-kernel@...r.kernel.org,
	kexec@...ts.infradead.org, hpa@...or.com,
	Peter Jones <pjones@...hat.com>,
	Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH 4/6] kexec: A new system call, kexec_file_load, for in kernel kexec

Vivek Goyal <vgoyal@...hat.com> writes:

> On Thu, Dec 19, 2013 at 01:54:39PM +0100, Torsten Duwe wrote:
>> On Tue, Nov 26, 2013 at 09:27:59AM -0500, Vivek Goyal wrote:

>> IMO it's up to user land to search lists of certificates, and present
>> only the final chain of trust to the kernel for checking.
>> 
>> ELF is the preferred format for most sane OSes and firmware, and a detached
>> signature would probably be simplest to check. If we have the choice,
>> without restrictions from braindead boot loaders, ELF should be first.
>> And if the pesigning isn't usable and another sig is needed anyway,
>> why not apply that to vmlinux(.gz) ?
>
> I have yet to look deeper into it that if we can sign elf images and
> just use elf loader. And can use space extract the elf image out of 
> a bzImage and pass it to kernel.
>
> Even if it is doable, one disadvantage seemed to be that extracted 
> elf images will have to be written to a file so thta it's file descriptor
> can be passed to kernel. And that assumed writable root and we chrome
> folks seems to have setups where root is not writable.

In that case the chrome folks would simply have to use an ELF format
kernel and not a bzImage.

Eric
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