His father, Aldo Santorum, came over from Italy at the age of seven. Of course, Ricky was born in Virginia, so he is automatically natural born. Not that it matters, however, because he's not going to be the nominee.
No, but Sen. Santorum's father was presumably naturalized at some point, either with his father or of his own accord, before the birth of Sen. Santorum. Such naturalization documents are yet to be disclosed to the public though.