On 01/22/2014 03:52 AM, Daniel P. Berrange wrote:
On Tue, Jan 21, 2014 at 10:47:07AM -0700, Eric Blake wrote:
I noticed that we allow virDomainGetVcpusFlags even for read-only connections, but that with a flag, it can require guest agent interaction. It is feasible that a malicious guest could intentionally abuse the replies it sends over the guest agent connection to possibly trigger a bug in libvirt's JSON parser, or withhold an answer so as to prevent the use of the agent in a later command such as a shutdown request. Although we don't know of any such exploits now (and therefore don't mind posting this patch publicly without trying to get a CVE assigned), it is better to err on the side of caution and explicitly require full access to any domain where the API requires guest interaction to operate correctly.
I audited all commands that are marked as conditionally using a guest agent. Note that at least virDomainFSTrim is documented as needing a guest agent, but that such use is unconditional depending on the hypervisor (so the existing domain:fs_trim ACL should be sufficient there, rather than also requirng domain:write). But when designing future APIs, such as the plans for obtaining a domain's IP addresses, we should copy the approach of this patch in making interaction with the guest be specified via a flag, and use that flag to also require stricter access checks.
ACK
Thanks; pushed. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org