Get the latest tech news

A more robust raw OpenBSD syscall demo


gram.com/blog/2025/03/06/ 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.

on flak yesterday, with a neat demonstration of OpenBSD’s pinsyscall security feature, whereby only pre-registered addresses are allowed to make system calls. The original demo is fragile for multiple reasons, and requires manually locating and entering addresses for each build. Very importantly I’ve added noinline to prevent these functions from being inlined into additional copies of the syscall instruction, which of course won’t be registered.

Get the Android app

Or read this on Hacker News

Read more on:

Photo of robust raw OpenBSD

robust raw OpenBSD

Photo of syscall demo

syscall demo