[userbinator]

Filesystem permissions cannot be controlled on a per app level.

I thought that's how Android's filesystem permission works? Each app runs as its own "user", and the FS permission bits restrict what it can access. This is a common solution in the Unix world. The problem on Android is that the filesystem is relatively hidden, and there's no easy way to change those permissions to allow more or less access.

Perhaps having the user as "root", along with all the actually-trusted apps (including those from the OS), and everything else setuid to their own per-app users, would be a useful configuration. Everything that's fully trusted is free to interact, while isolating those which aren't.

I do not like the fact, that an installation of for example a game needs admin rights, and has every chance to access data it should not be able to do.

That's possibly because of a need to install kernel-mode components (might be DRM related). If you're truly paranoid, VMs would be a better choice for isolation. But fundamentally, I don't believe in installing/using/changing apps that I don't completely trust, so perhaps this is a less of a problem for me and I'd rather have everything be "open".