I've been trying to consider how Row Level Security could be implemented with the Entity Framework. The idea is to have a database agnostic means that would offer methods to restrict the rows coming from the ObjectContext.
Some of my inital ideas have involved modifying the partial classes created by the EDMGEN tool and that has offered some limited support. Users are still able to get around this solution by using their own eSQL statements and a QueryObject.
I've been looking for a comprehensive solution that would exist above the database providers so that it would remain agnostic.