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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20131122160837.GJ4046@redhat.com>
Date:	Fri, 22 Nov 2013 11:08:37 -0500
From:	Vivek Goyal <vgoyal@...hat.com>
To:	Jiri Kosina <jkosina@...e.cz>
Cc:	Eric Paris <eparis@...isplace.org>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	"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, Nov 22, 2013 at 05:04:04PM +0100, Jiri Kosina wrote:
> 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.

I am assuming that in above scenario, kernel will run in locked down
mode (something what matthew implemented for secureboot). Where /dev/mem
write access will be disabled and only signed modules will be loaded.

Thanks
Vivek
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/