Shanghai to Lhasa ticket

This is no limitation for buying the ticket but you need to show the Travel Permit for boarding. But I heard that for the Lhasa trip once the ticket issued, it is hard to make a change or cancellation since you need to go to the station in person for that. So you'd better book it after the schedule fixed. Based on the real name policy, you can only buy one ticket for each person. Thus to have the whole cabin of your own, you would need passports of 4 people.