Is this what you're ref too: Official Baseball Rules: Home (umpirebible.com)
Rule 5.09(a)(2) Comment: "Legally caught" means in the catcher's glove before the ball touches the ground. It is not legal if the ball lodges in his clothing or paraphernalia; or if it touches the umpire and is caught by the catcher on the rebound.
If a foul tip first strikes the catcher's glove and then goes on through and is caught by both hands against his body or protector, before the ball touches the ground, it is a strike, and if third strike, batter is out. If smothered against his body or protector,