I've only dabbled, so I'm happy to have people with more linux-side knowledge to call me out on any inaccuracies here, but...

io_uring is effectively as "secure" as any other syscall unto itself. The issue is that the mechanism by which io_uring makes its syscalls as part of its submission/completion queues means that those underlying syscalls can't be filtered by seccomp. The real question is your security posture.

If you're writing a hypervisor that's intended to partition resources between underlying users in a secure fashion, the ability for io_uring to bypass seccomp is largely a non-starter. But if you own the machine and you just want to run an application on it (i.e. an HTTP server that uses io_uring for file/network io) you should largely be in the clear.

▲

linuxnewb99 4 days ago | parent [-]

Does it no longer suffer from TOCTOU?

	▲	seangrogg 3 days ago \| parent [-]
		I don't consider myself fully qualified to speak to this, so please take it with a grain of salt. From what I gather it seems like you could potentially create scenarios where TOCTOU is indeed a problem, but in considering the situations where it could come up I do feel like all my ideas are somewhat contrived in nature. And even when noodling on it I very much get the feeling that I return to my previous statement: consider what you're building. I think that the potential for TOCTOU could potentially compromise a hypervisor's security (i.e. letting an arbitrary number of user on a system make arbitrary io_uring calls) and even if I couldn't demonstrate how that could be weaponized I would avoid it. However, if you're writing an application that's going to do a read(2) or something, I don't see TOCTOU being a uniquely io_uring problem.