alevy/hails — Issue #4: Changing collection clearance
Author: deian
Created: 2012-01-22 02:44:53+00:00
State: open

Suppose we have a collection with clearance L_C0. We insert a document D whose label is L_C0. Following the collection clearance is changed to L_C1 such that L_C0 does not flow to L_C1. Now we retrieve document D from the collection -- its label L_C0 is above the collection clearance L_C1 (which would violate the desired property: read>>= write ⇒ return ()). An approach is to serialize the clearance into the collection and make sure that it can only be lowered.