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

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Message-ID: <alpine.LNX.2.00.1311221701510.22082@pobox.suse.cz>
Date:	Fri, 22 Nov 2013 17:04:04 +0100 (CET)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Eric Paris <eparis@...isplace.org>
Cc:	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Vivek Goyal <vgoyal@...hat.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	kexec@...ts.infradead.org, "H. Peter Anvin" <hpa@...or.com>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Greg Kroah-Hartman <greg@...ah.com>
Subject: Re: [PATCH 0/6] kexec: A new system call to allow in kernel
 loading

On Fri, 22 Nov 2013, Eric Paris wrote:

> Consider a cloud provider who gives their customer a machine where
> they, the cloud provider, is specifying the kernel and initrd.  This
> is a real thing that people do today.  Root on the machine has ZERO
> control over the kernel, bootloader, and initrd.  Check it out,
> qemu/kvm can do this.  But, there is no way to disable kexec if the
> distro configures it in (well, there is in RHEL at least).  

If that root can load LKMs, access /dev/mem, or whatever else, there is 
not really a point disabling kexec anyway, is the same thing can be 
implemented (although with more hassle, of course) through these channels 
as well.

-- 
Jiri Kosina
SUSE Labs
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