Linus Torvalds Approves New Kernel ‘Lockdown’ Feature

“After years of countless reviews, discussions, and code rewrites, Linus Torvalds approved on Saturday a new security feature for the Linux kernel, named ‘lockdown’,” reports ZDNet: The new feature will ship as a LSM (Linux Security Module) in the soon-to-be-released Linux kernel 5.4 branch, where it will be turned off by default; usage being optional due to the risk of breaking existing systems. The new feature’s primary function will be to strengthen the divide between userland processes and kernel code by preventing even the root account from interacting with kernel code — something that it’s been able to do, by design, until now.

When enabled, the new “lockdown” feature will restrict some kernel functionality, even for the root user, making it harder for compromised root accounts to compromise the rest of the OS… “When enabled, various pieces of kernel functionality are restricted,” said Linus Torvalds, Linux kernel creator, and the one who put the final stamp of approval on the module yesterday. This includes restricting access to kernel features that may allow arbitrary code execution via code supplied by userland processes; blocking processes from writing or reading /dev/mem and /dev/kmem memory; block access to opening /dev/port to prevent raw port access; enforcing kernel module signatures; and many more others, detailed here.