Next steps toward mimmutable, from deraadt@
by from OpenBSD Journal on (#661AC)
In a recent message to the tech mailing list, Theo de Raadt (deraadt@) summarized the state of the new memory protections work. The thread also includes a followup from Otto Moerbeek (otto@) on consequent changes to the memory allocation mechanisms.
Theo writes,
From: "Theo de Raadt" <deraadt () openbsd ! org>Date: Fri, 18 Nov 2022 03:10:05 +0000To: openbsd-techSubject: More on mimmutable[LONG]I am getting close to having the big final step of mimmutable in the tree.Here's a refresher on the how it works, what's already done, and the nextbit to land.DESCRIPTION The mimmutable() system call changes currently mapped pages in the region to be marked immutable, which means their protection or mapping may not be changed in the future. mmap(2), mprotect(2), and munmap(2) to pages marked immutable will return with error EPERM.