Correct, EFS lenses have an alternative mounting configuration that only APS-C crop bodies allow. Sure, you can alter the lens to fit the mount, but you run the risk of mirror slap on the rear of the lens with a FF, less so with an APS-H crop body.
The widest FF lens you can use is the Sigma 12-24mm at this time. Otherwise you have the Tokina 11-16mm f2.8 that would work at 16mm, the 17-40L, the 16-35L, Tamron 16-28, and a very small misc other list of lenses.
EDIT: so let's grab some popcorn and see how far this reply count goes, when this was a simple question with a simple answer.