no wifi in dorm room

My sons dorm has no wifi. They don't allow routers in the rooms.
They do have an ethernet connection in the room.
He has a macbook pro and an iphone 5.

Is there any way he can use his phone through the macbook so he does not use all the data plan.
Also, I have seen some adapters for ethernet to iPhone....not sure if that would work though.

thanks for any help

Yes there is. In System Preferences, open the Sharing section, and turn on Internet Sharing. He'll want to share his ethernet connection over WiFi. I'd recommend setting a password for it, but other than that, he should be able to connect his iPhone to his dorm's ethernet connection.