Passive vent question

[kan]

Have some passive vents from bedroom ceilings being vented through the attic to a vent tile on the roof which seem to be leaking. I can only presume there is water getting in further up the roof which is then running doing the sarking felt and in through the hole made in the sarking felt for the vent tile/flexi hose as there is water marks on the sarking felt above the vent tile.
I have fitted durgo valves on soil stacks before and wonder is there a similar device for passive air vents to save me having to vent out to the roof. Would need to be compliant with building regs

Thanks