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

Zhangbo (Oscar) oscar.zhangbo at huawei.com
Fri Aug 25 08:59:54 UTC 2017

>On Fri, Aug 25, 2017 at 06:45:18AM +0000, Zhangbo (Oscar) wrote:
>>Hi all:
>>     The Host Administrator is capable of running any exec in guests via the
>qemu-ga command "guest-exec", eg:
>>        virsh qemu-agent-command test_guest '{"execute": "guest-exec",
>"arguments": {"path": "ifconfig", "arg": [ "eth1", "" ],"capture-output":
>true } }'
>>       virsh qemu-agent-command test_guest '{"execute": "guest-exec-status",
>"arguments": { "pid": 12425 } }'
>>      The example above just change the guests' ip address, the Administrator
>may also change guests' user password, get sensitive information, etc. which
>causes Insider Access.
>>      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?
>>      Thanks!
>What's your setup that this, in particular, is your concern?  Do you
>have everything encrypted by keys that are not reachable for the host
>administrator?  How are those saved?  For example, how do you guard
>against the host administrator killing the domain?  Or mounting the disk

Killing the domain is acceptable somehow at some degree, but leaking sensitive
information, for example, trade secret, is horrible. We most concern is to protect
that information by (maybe)disabling "guest-exec" guest commands etc. 

Another concern, as mentioned in another mail, is that, if the cloud tenant himself 
installed the guest agent, and doesn't know the "adding --blacklist" issue, that guest is in danger.

>of the domain, doing whatever they want to with it and starting it back?
>Or million other things that come to mind.  Not trusting the host
>administrator is kinda (well, precisely) like not trusting root on *NIX
>P.S.: Maybe more aluminium could help, but I haven't tried yet.
>>Best Regrads
>>libvir-list mailing list
>>libvir-list at redhat.com

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