Nope, no restriction on flying through them. They are depicted on VFR charts and information about the drop zones can be found in an A/FD. It is always the pilot's responsability to see and avoid, but the jump pilot also has to broadcast over the local CTAF prior to jumpers, and when they jump, and what altidude they're jumping from.
Forgive me if I don't know the details, as I don't fly jump planes, this is just based on what I've observed when flying near dropzones.
Happy contrails - I support B747Skipper and Jetguy