Re: [Xen-devel] [RFC PATCH 0/18] Xenstore stub domain

[Joanna Rutkowska <joanna@xxxxxxxxxxxxxxxxxxxxxx>]

On 01/12/12 12:27, Ian Campbell wrote:
> On Thu, 2012-01-12 at 10:48 +0000, Tim Deegan wrote:
>> At 11:33 +0100 on 12 Jan (1326367997), Joanna Rutkowska wrote:
>>> Daniel,
>>>
>>> Can you explain what is the rationale for moving the xenstored into a
>>> stubdom? After all, if an attacker is able to compromise the xenstored,
>>> there should be many ways now how to compromise other VMs in the system?
>>> And it shouldn't matter whether the xenstored is in stubdom or whether
>>> in Dom0. E.g. the attacker might redirect the block fronts to us some
>>> false block backends, so that the VMs get compromised fs. One could
>>> probably think of other attacks as well...?
>>
>> I think the point is to protect xenstore from dom0, not dom0 from
>> xenstore.  With stub-xenstore and driver domains, only the domain
>> builder and PCIback need to have any privilege, and they can be moved
>> out of dom0 too (e.g., http://dl.acm.org/citation.cfm?id=1346278 ,
>> http://tjd.phlegethon.org/words/sosp11-xoar.html)
> 
> Also by isolating components you gain the ability to restart them
> independently. Since xenstored is one of (the only?) dom0 component
> which cannot be trivially restarted so putting it in a separate domain
> means you can restart dom0.
> 

But why would anybody want to restart Dom0, in the first place?

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