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From: Markus Armbruster <armbru@redhat.com>
To: Sasha Levin <levinsasha928@gmail.com>
Cc: Pekka Enberg <penberg@kernel.org>, Anthony Liguori <anthony@codemonkey.ws>,
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        kvm@vger.kernel.org, Christoph Hellwig <hch@lst.de>
Subject: Re: [RFC/GIT PULL] Linux KVM tool for v3.2
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	<m3pqh0tnoi.fsf@blackfin.pond.sub.org>
	<CA+1xoqe22z9F3ZyFG_XnV9Y17HtkeSxtf1gbW4+CW1cuNQ=N5g@mail.gmail.com>
Date: Thu, 10 Nov 2011 09:57:01 +0100
In-Reply-To: <CA+1xoqe22z9F3ZyFG_XnV9Y17HtkeSxtf1gbW4+CW1cuNQ=N5g@mail.gmail.com>
	(Sasha Levin's message of "Thu, 10 Nov 2011 10:23:23 +0200")
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Sasha Levin <levinsasha928@gmail.com> writes:

> On Thu, Nov 10, 2011 at 9:57 AM, Markus Armbruster <armbru@redhat.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".

> I'm actually not sure why KVM tool got QCOW support in the first
> place. You can have anything QCOW provides if you use btrfs (among
> several other FSs).

Maybe it's just me, but isn't it weird to have a filesystem (QCOW2)
sitting in the kernel sources that you can't mount(2)?