I wouldn't so far as saying that it's "normal" - but I've seen contracts like that. I've never signed them :-)

If you want to know what you can actually do - you need to show your contract to a lawyer. The scope of the land grab may not be as bad as you think depending on the exact language used. Some of the land grab may not be legal, depending on the language used and your exact working arrangement.

And next time please, please read, understand and possibly amend the contract before you sign :-) It's just about the strongest negotiation position you'll have. When they want you and you haven't signed.