[libvirt] [Qemu-devel] NBD TLS support in QEMU

[Benoît Canet]

The Wednesday 03 Sep 2014 à 17:44:17 (+0100), Stefan Hajnoczi wrote :
> Hi,
> QEMU offers both NBD client and server functionality.  The NBD protocol
> runs unencrypted, which is a problem when the client and server
> communicate over an untrusted network.
> 
> The particular use case that prompted this mail is storage migration in
> OpenStack.  The goal is to encrypt the NBD connection between source and
> destination hosts during storage migration.

I agree this would be usefull.

> 
> I think we can integrate TLS into the NBD protocol as an optional flag.
> A quick web search does not reveal existing open source SSL/TLS NBD
> implementations.  I do see a VMware NBDSSL protocol but there is no
> specification so I guess it is proprietary.
> 
> The NBD protocol starts with a negotiation phase.  This would be the
> appropriate place to indicate that TLS will be used.  After client and
> server complete TLS setup the connection can continue as normal.

Prenegociating TLS look like we will accidentaly introduce some security hole.
Why not just using a dedicated port and let the TLS handshake happen normaly ?

Best regards

Benoît
> 
> Besides QEMU, the userspace NBD tools (http://nbd.sf.net/) can also be
> extended to support TLS.  In this case the kernel needs a localhost
> socket and userspace handles TLS.
> 
> Thoughts?
> 
> Stefan