It does raise the question about if it would be possible by the kernel to implement features that so to say erect city walls in a way that processes can't acces

It does raise the question about if it would be possible by the kernel to implement features that so to say erect city walls in a way that processes can't access whatever it want. Ie, granting access to some of the ethernet DMA but not all of it, or something similar. Perhaps it isn't possible in theory, but perhaps it is, or could be.