[PATCH v3 0/1] Add a sysctl to disable io_uring system-wide

[Matteo Rizzo <matteorizzo@google.com>]

Over the last few years we've seen many critical vulnerabilities in
io_uring[1] which could be exploited by an unprivileged process to gain
control over the kernel. This patch introduces a new sysctl which disables
the creation of new io_uring instances system-wide.

The goal of this patch is to give distros, system admins, and cloud
providers a way to reduce the risk of privilege escalation through io_uring
where disabling it with seccomp or at compile time is not practical. For
example a distro or cloud provider might want to disable io_uring by
default and have users enable it again if they need to run a program that
requires it. The new sysctl is designed to let a user with root on the
machine enable and disable io_uring systemwide at runtime without requiring
a kernel recompilation or a reboot.

[1] Link: https://goo.gle/limit-iouring

---
v3:
	* Fix the commit message
	* Use READ_ONCE in io_uring_allowed to avoid races
	* Add reviews
v2:
	* Documentation style fixes
	* Add a third level that only disables io_uring for unprivileged
	  processes


Matteo Rizzo (1):
  io_uring: add a sysctl to disable io_uring system-wide

 Documentation/admin-guide/sysctl/kernel.rst | 19 +++++++++++++
 io_uring/io_uring.c                         | 31 +++++++++++++++++++++
 2 files changed, 50 insertions(+)


base-commit: 1601fb26b26758668533bdb211fdfbb5234367ee
-- 
2.41.0.255.g8b1d071c50-goog