The "kernel runtime security instrumentation" (KRSI) patch set has been making the rounds over the past few months; the idea is to use the Linux security module (LSM) hooks as a way to detect, and potentially deflect, active attacks against a running system. It does so by allowing BPF programs to be attached to the LSM hooks. That has caused some concern in the past about exposing the security hooks as external kernel APIs, which makes them potentially subject to the "don't break user space" edict. But there has been no real objection to the goals of KRSI. The fourth version of the patch set was posted by KP Singh on February 20; the concerns raised this time are about its impact on the LSM infrastructure.