Microsoft has published a patch-set for the Linux kernel, proposing the Hornet Linux Security Module (LSM). If you haven’t been keeping up with the kernel contributor scoreboard, Microsoft is #11 at time of writing and that might surprise you. The reality is that Microsoft’s biggest source of revenue is their cloud offering, and Azure is over half Linux, so Microsoft really is incentivized to make Linux better.
The Hornet LSM is all about more secure eBPF programs, which requires another aside: What is eBPF? First implemented in the Berkeley Packet Filter, it’s a virtual machine in the kernel, that allows executing programs in kernel space. It was quickly realized that this ability to run a script in kernel space was useful for far more than just filtering packets, and the extended Berkeley Packet Filter was born. eBPF is now used for load balancing, system auditing, security and intrusion detection, and lots more.
This unique ability to load scripts from user space into kernel space has made eBPF useful for malware and spyware applications, too. There is already a signature scheme to restrict eBPF programs, but Hornet allows for stricter checks and auditing. The patch is considered a Request For Comments (RFC), and points out that this existing protection may be subject to Time Of Check / Time Of Use (TOCTOU) attacks. It remains to be seen whether Hornet passes muster and lands in the upstream kernel. Continue reading “This Week In Security: Hornet, Gogs, And Blinkenlights”
