Comment 30 for bug 1392504

Hey nickmaelao, your outputs show you've only changed the ownership of the USB bus and not the USB device itself...I'd suspect if you looked at 'ls -la /dev/bus/usb/001/' then the actual USB device will still have root ownership. Ergo if libvirtd is still creating the vm's with qemu and a non-root user you will still have the problem.

chmod libvirt-qemu:kvm /dev/bus/usb/001/xxx (xxx being the USB device numeber) should resolve.

Alternatively you could change /etc/libvirtd/qemu.conf and make libvirtd create guests with qemu as the root user, look for the 'user = ' and 'group = ' lines. I can't comment on the risk associated to this so you'll need to look into that yourself but I've taken this approach and have no problems with USB attachment and I don't need to manually change device ownerships.