Unless there is an announcement, photographer is generally permitted. As said above, you need to listen for an announcement or watch for signs.
On some rides, they say "no flash photography" That means you can take pictures, but don't use your flash because it's distracting to other guests on a dark ride.
Then there are rides where all photography is prohibited. Star Tours is a good example there. It's part of the opening presentation by one of the droids just before you enter.