In one embodiment, a gateway device receives, from a centralized broker device, a data-access policy for a given computer network, the data-access policy defining which of one or more accessing entities are granted access to specific elements of data within the given computer network. When the gateway device then receives, from a particular accessing entity, a request for one or more particular elements of data from within the given computer network, it may determine, based on the data-access policy, whether the particular accessing entity has been granted access to each of the one or more particular elements of data of the request. As such, the gateway device may prevent access for the particular accessing entity to any of the one or more particular elements of the data request to which the particular accessing entity has not been granted access.