It's certainly possible. I've seen it done on a UK TV DIY type show a few years ago. But more reliably, my wife's b-i-l (my s-i-l's hubby), who works in a paint store and knows about this stuff, has re-painted his bath in the last few months, after a disaster with the wrong cleaning product. Can't say what the actual paint used was, but presume it was special for the purpose.
Your best bet is to find a similar paint store (that serves the trade as well as public), in your area and ask them. As recommended above, be sure you know what type of bath you have.
If you haven't already "googled"
painting a bath, it might be an idea. The following link was on one of the search results:
http://www.whiteknightpaints.com.au/...iew/tub-n-tile