linux-kernel - Re: [Xen-devel] [PATCH v3 00/11] xen: Initial kexec/kdump implementation

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Message-ID: <50F07E2D.6010602@zytor.com>
Date:	Fri, 11 Jan 2013 13:03:41 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Vivek Goyal <vgoyal@...hat.com>
CC:	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Daniel Kiper <daniel.kiper@...cle.com>,
	"xen-devel@...ts.xensource.com" <xen-devel@...ts.xensource.com>,
	Andrew Cooper <andrew.cooper3@...rix.com>,
	"x86@...nel.org" <x86@...nel.org>,
	"kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"virtualization@...ts.linux-foundation.org" 
	<virtualization@...ts.linux-foundation.org>,
	"mingo@...hat.com" <mingo@...hat.com>,
	Jan Beulich <JBeulich@...e.com>,
	"maxim.uvarov@...cle.com" <maxim.uvarov@...cle.com>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	David Howells <dhowells@...hat.com>
Subject: Re: [Xen-devel] [PATCH v3 00/11] xen: Initial kexec/kdump implementation

On 01/11/2013 12:52 PM, Vivek Goyal wrote:
> 
> Eric,
> 
> In a private conversation, David Howells suggested why not pass kernel
> signature in a segment to kernel and kernel can do the verification.
> 
> /sbin/kexec signature is verified by kernel at exec() time. Then
> /sbin/kexec just passes one signature segment (after regular segment) for
> each segment being loaded. The segments which don't have signature,
> are passed with section size 0. And signature passing behavior can be
> controlled by one new kexec flag.
> 
> That way /sbin/kexec does not have to worry about doing any verification
> by itself. In fact, I am not sure how it can do the verification when
> crypto libraries it will need are not signed (assuming they are not
> statically linked in).
> 
> What do you think about this idea?
> 

A signed /sbin/kexec would realistically have to be statically linked,
at least in the short term; otherwise the libraries and ld.so would need
verification as well.

Now, that *might* very well have some real value -- there are certainly
users out there who would very much want only binaries signed with
specific keys to get run on their system.

	-hpa


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