Recently that has been a big crack down on people who disobey the rules and take photos in the tombs. Especially in the valley of kings where culprits are being taken to the inspectors office, having to delete their entire memory card and pay a substantial fine. I am not saying that some people are not still getting away with it, especially in the valley of nobles but you have been warned.
Permission can be arranged, I know people studying here who have got it. It is expensive and you have to be accompanied by an inspector