Security and safety of Linux systems in a BPF-powered hybrid user space/kernel world

With the introduction of BPF into the Linux kernel, we are seeing a sea change in the traditional application model. With BPF it is now possible to execute parts of the application logic in kernel space, leading to a novel hybrid userspace/kernel model. This is an exciting development that brings with it many opportunities, but also some challenges especially in the area of security. We have recently seen an example of this around the “kernel lockdown” functionality in the kernel, which would disable BPF entirely in its “confidentiality” mode.