linux-kernel - Re: Kdump with signed images

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Date:	Thu, 01 Nov 2012 09:10:56 -0600
From:	Khalid Aziz <khalid@...ehiking.org>
To:	Matthew Garrett <mjg@...hat.com>
Cc:	Vivek Goyal <vgoyal@...hat.com>,
	Dmitry Kasatkin <dmitry.kasatkin@...el.com>,
	Kees Cook <keescook@...omium.org>,
	Mimi Zohar <zohar@...ux.vnet.ibm.com>,
	kexec@...ts.infradead.org,
	linux kernel mailing list <linux-kernel@...r.kernel.org>,
	horms@...ge.net.au, "Eric W. Biederman" <ebiederm@...ssion.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Roberto Sassu <roberto.sassu@...ito.it>,
	Dave Young <dyoung@...hat.com>
Subject: Re: Kdump with signed images

On Thu, 2012-11-01 at 14:57 +0000, Matthew Garrett wrote:
> On Thu, Nov 01, 2012 at 10:51:49AM -0400, Vivek Goyal wrote:
> 
> > And if one wants only /sbin/kexec to call it, then just sign that
> > one so no other executable will be able to call kexec_load(). Though
> > I don't think that's the requirement here. Requirement is that only
> > trusted executables should be able to call kexec_load().
> 
> Where "trusted executables" means "signed by a key that's present in the 
> system firmware or in the kernel that's signed with a key that's present 
> in the system firmware", sure.
> 

This is starting to sound too restrictive (even though I understand the
rationale behind the restrictions). Does this allow for a custom
userspace application that among other things also can kexec_load() a
new kernel and boot it, for example a customer unique health monitoring
app that reboots the system if things are not looking right on the
running system? How would a customer go about getting that userspace
binary signed and re-signed every time they update their app? There is
the option of turning the whole SecureBoot thing off for a system like
that but let us assume customer wants to leave that on or does not have
the option to turn it off?

--
Khalid

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