The white smoke coming from your exhaust may indicate that you have water leaking from your coolant system through the head gasket into the combustion chamber. The water will be burnt with the fuel causing vapour coming from your exhaust.
As for the oil leak perhaps it may not be coming from the exhaust and may be coming from the rocker cover gasket or head gasket. A car should not leak oil when parked unless there is a crack in the sump as oil does not circulate around the vehicle when the engine is off. Assuming when you say parked is with the engine off.
Taking into account that you have white smoke coming from the tailpipe and also this oil leak problem I would say it's the head gasket that has failed as both these problems can relate to the head gasket. What I recommend you do before proceeding is check if you coolant has any mustard like substance indicating that your oil and coolant has mixed due to head gasket failure.