Comment 5 for bug 1552241

Glad to see that the problem is confirmed. I'm uncomfortable about the blanket allow for /run/udev/data/* as a general solution, as you've said, there's a lot there.

I had found the /etc/apparmor.d/libvirt/libvirt-<uuid>[.files] sections, it looks like I must have edited it to allow the usb passthrough in 14.04 from the entry there.