> How would one enforce that an app is allowed to access health data but doesn't forward it to the internet? User-mode code can’t do any IO or networking by it

> How would one enforce that an app is allowed to access health data but doesn't forward it to the internet? User-mode code can’t do any IO or networking by itself. Instead, apps call OS kernels asking to open files or sockets for them. It’s impossible to disable forwarding just for the health data, but it’s easy for an OS to completely disable any TCP/IP networking for an app which uses health data. Apple and Google are struggling with that problem because in their ecosystems many developers rely on in-app advertisements, and Google is even running its own ads network.