The only real untouchables on the Diamondbacks are Max Scherzer and Justin Upton.
Certainly there is the core here that we don't want to break (Drew, Reynolds, Haren, Montero) but I wouldn't call them untouchable. That said, we would have to be BLOWN AWAY to trade Haren. He's signed for another few years at a pretty cheap price, and with the uncertanty of our rotation with Davis and Garland gone and Webb coming off a major injury (assuming we even pick up his option), Haren is exceptionally valuable to us.
The Angels called us at the trade deadline about Haren this year, and our GM said he's not going anywhere.
In short, I don't want to say 'untouchable', but he's the next closest thing. We would want the farm for him for sure, so I wouldn't get your hopes up about it.