Moderator, Iberia Airlines, Airport Lounges, and Ambassador, British Airways Executive Club
Join Date: Feb 2010
Programs: BA Lifetime Gold; Flying Blue Life Platinum; LH Sen.; Hilton Diamond; Kemal Kebabs Prized Customer
Posts: 63,799
Yes, perfectly OK to take your own food and drink on board, including alcoholic drinks on board. I don't think it has ever been banned, though other airlines choose to take a different approach.
More information, photos and airport purchase options on this topic in the Information thread for BOB.