I don't have my book here at the moment, so I can't quote the
specific FARs, but I think they say you must have permission
before landing. Because all land is owned by someone (generally)
you cannot land anywhere without permission.

There is no such FAR. As far as the feds are concerned, they don't
care where you land (as long as it's a safe place to land).
John Galban=====N4BQ (PA28-180)