[libvirt] security: the qemu agent command "guest-exec" may cause Insider Access

Zhangbo (Oscar) oscar.zhangbo at huawei.com
Sat Aug 26 01:05:46 UTC 2017

>On Fri, Aug 25, 2017 at 08:52:16 +0000, Zhangbo (Oscar) wrote:
>> >On Fri, Aug 25, 2017 at 06:45:18 +0000, Zhangbo (Oscar) wrote:
>> >>       The Administrator also can use other commands such as "
>> >guest-file-open" that also cause Insider Access.
>> >>
>> >>       So, how to avoid this security problem, what's your suggestion?
>> >
>> >You can use the "--blacklist" facility of qemu-ga to disable APIs you
>> >don't want to support. Or don't run the guest agent at all.
>> This works if the qemu-agent inside the guest is installed by us cloud provider.
>But if the guest
>> is installed all by the cloud tenant himself, he may not know to add "--blacklist"
>by default, and
>> doesn't notice that his OS is opposed to host attackers. How to solve this
>problem? It seems that
>> we have to mitigate the treat on the host side?
>That premise is silly. Adding protection from the host on the host side
>does not make sense, since the host admin can always change it.
>You can avoid adding the guest agent channel though completely. On the
>guest, you can e.g. not install the guest agent.
>If you don't trust the host, don't use it. There's no protection from
>reading the memory or disk images currently. See [1]. Note that even
>without the API, root can access all the stuff.

Thank you very much for the detailed reply, any future plan to solve such problem(host 
has too high authority to access guests' memory things)? What will be the potential mitigation?

>[1]: http://libvirt.org/html/libvirt-libvirt-domain.html#virDomainMemoryPeek

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