What is the condition of the whitewash or stucco surfaces? If it is not peeling or flaking, you should be able to clean the surface and repaint. If it is flaking or peeling, use a scrubrush or wire brush followed by pressureized water and clean the surface removing all loose material. After it has dried finish with a paint approved for masonry surfaces. Best painting results are with airless spray followed by roller keeping a wet edge.