Controller does not validate updated subnet size

[markdryan]

This is based on an inspection of the code so I could be mistaken. However, as far as I can tell controller does not validate the tenant subnet size when processing a tenant update command. Ciao-cli does perform some validation so it's hard to actually exploit this. Nonetheless, it should be possible to construct a json package with invalid data which would potentially destabilize controller. Note the subnet size is verified by controller when creating a new tenant.

[markdryan]

So we check here when creating a tenant

https://github.com/ciao-project/ciao/blob/master/ciao-controller/tenants.go#L82

but not here when updating one

https://github.com/ciao-project/ciao/blob/master/ciao-controller/tenants.go#L69