“Players are entitled to an interval at half-time, not exceeding 15 minutes; a short drinks break (which should not exceed one minute) is permitted at the interval of half-time in extra time. Competition rules must state the duration of the half-time interval and it may be altered only with the referee’s permission.”
Duration of football match, football halftime duration, abandoned football match rules
www.theifab.com
Half-time at the World Cup final between Spain and Argentina is set to be the longest in the tournament's history.
www.bbc.com