A more robust raw OpenBSD syscall demo

Ted Unangst published dude, where are your syscalls? on flak yesterday, with a neat demonstration of OpenBSD’s pinsyscall security feature, whereby only pre-registered addresses are allowed to make system calls. Whether it strengthens or weakens security is up for debate, but regardless it’s an interesting, low-level programming challenge. The original demo is fragile for multiple reasons, and requires manually locating and entering addresses for each build. In this article I show how to fix it. To prove that it’s robust, I ported an entire, real application to use raw system calls on OpenBSD.
↫ Chris Wellons

Some light reading for the weekend.