I emailed MPSSAA to double check, but M&T Bank policy is as follows.
Admission Policy
All gates open 2 hours prior to kickoff. Due to heightened security measures at the gates, we strongly urge all guests to arrive at the stadium as early as possible to avoid entrance delays, particularly in colder weather. Re-entry into M&T Bank Stadium is not permitted. If medication is required, be sure to have it with you upon entry. All guests entering the stadium are subject to search. Refusal to comply may be grounds to prohibit admission. Guest will not be permitted to enter the stadium if they are visibly intoxicated.
Prohibited ItemsAir horns or horns of any kindArtificial noise makersBackpacksBattery heated clothing and/or seat cushionsBeveragesBinocular/Camera casesBottles (plastic or glass)Camera tripods and monopodsCansContainers/FlasksCoolers/ ThermosesCowbellsElectronic CigarettesFanny PacksFlag/banner polesFootballs or balls of any kindGrocery-type bagsHard Foam Beverage Holders/HandLaser pointers/pensPurses larger than the size of a handPlastic bagsSeat Cushions with a back, pocket, zipper, or with a foam core thicker than 1"Tote bagsUmbrellasVideo camerasWeapons or dangerous objectsWhistles