Neither the cans nor the wire need to be outdoor rated.
The wiring is in the ceiling of your porch is not exposed to rain so 14/2 romex is fine.
Assuming your talking about a farmers porch (essentially a deck with a roof over it just so we're clear) I have done this many times and not one inspector has ever said anything about the romex wiring.
-rick
Interesting- Now Lets look at the 2008 NEC and see what it says!
Article 100 Definitions-
Location Damp- Locations protected from weather and not subject to saturation with water or other liquids but subject to moderate degrees of moisture. Examples of such locations include partially protected locations under canopies, marquees,
roofed open porches, and like locations, and interior locations subject to moderate degrees of moisture, such as some basements, some barns, and some cold-storage warehouses.
So using this deffinition your farmers porch you could not use NM (romex)cable.
Article 334.12(B)
Types NM and NMS cables shall not be used under the following conditions or in the following locatons:
(1) Where exposed to crrosive fumes of vapors.
(2) Where embedded in masonry, concrete, Adobe, fill, or plaster.
(3) In a shallow chase in masonry, concrete, or adobe and covered with plaster, adobe, or similar finish.
(4)
In wet or damp locations.
