The immediate problem is an inability to use the KPI from the kernel itself. Some of the cloned drivers require additional information provided via the opaque pointer and it is not possible to specify whether this pointer references kernel-space or user-space.
Instead of just adding a flag, try to generalise the KPI so the next changes can be performed without touching all of the users.
In particular,
1. Unify current notion of `SIMPLE` and `ADVANCED` users.
Customers of the former rely on the framework to select the interface `unit`. Small amount of users also use 'minXXX' to auto-create (and preserve) a single interface such as 'pflog0'. Address the first part by requesting auto-unit selection via `IFC_C_AUTOUNIT` flag. Remove the ability to automatic interface creation as it won't allow to submit custom data to the interface, limiting its usage.