linux-kernel - Re: [RFC/GIT PULL] Linux KVM tool for v3.2

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Date:	Thu, 10 Nov 2011 11:14:31 +0200
From:	Sasha Levin <levinsasha928@...il.com>
To:	Avi Kivity <avi@...hat.com>
Cc:	Markus Armbruster <armbru@...hat.com>,
	Pekka Enberg <penberg@...nel.org>,
	Anthony Liguori <anthony@...emonkey.ws>,
	Pekka Enberg <penberg@...helsinki.fi>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org, Christoph Hellwig <hch@....de>
Subject: Re: [RFC/GIT PULL] Linux KVM tool for v3.2

On Thu, Nov 10, 2011 at 11:09 AM, Avi Kivity <avi@...hat.com> wrote:
> On 11/10/2011 11:04 AM, Sasha Levin wrote:
>> On Thu, Nov 10, 2011 at 10:57 AM, Markus Armbruster <armbru@...hat.com> wrote:
>> > Sasha Levin <levinsasha928@...il.com> writes:
>> >
>> >> On Thu, Nov 10, 2011 at 9:57 AM, Markus Armbruster <armbru@...hat.com> wrote:
>> > [...]
>> >>> Start with a clean read/write raw image.  Probing declares it raw.
>> >>> Guest writes QCOW signature to it, with a backing file of its choice.
>> >>>
>> >>> Restart with the same image.  Probing declares it QCOW2.  Guest can read
>> >>> the backing file.  Oops.
>> >>
>> >> Thats an excellent scenario why you'd want to have 'Secure KVM' with
>> >> seccomp filters :)
>> >
>> > Yup.
>> >
>> > For what it's worth, sVirt (use SELinux to secure virtualization)
>> > mitigates the problem.  Doesn't mean we couldn't use "Secure KVM".
>>
>> How does it do it do that? You have a hypervisor trying to read
>> arbitrary files on the host FS, no?
>
> Trying and failing.  sVirt will deny access to all files except those
> explicitly allowed by libvirt.

It still allows the guest to read more than enough files which it
shouldn't be reading.

Unless you configure sVirt on a per-guest basis...
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