Io_uring support rocky 9.3

Rocky Linux General
1

Red Hat has already supported io_uring in RHEL 9.3. According to the Red Hat documentation, the related system calls may either succeed or return EPERM. However, I received ENOSYS on Rocky 9.3.

2

You’ve not provided enough information on your issue. You must be running at least kernel 5.14.0-362.8.1.el9_3.x86_64 on your system for io_uring.

If you feel it’s an issue or a bug with our builds, please report it to bugs.rockylinux.org with all the relevant information, such as reproduction steps, logs, and other relevant system configuration.

3

I don’t know where the problem occurred, but I can confirm that my kernel version is fine.(5.14.0-362.13.1.el9_3.x86_64) My question is whether Rocky Linux currently supports io_uring?Has it passed the CI tests?

4

Are you sure? You said you got ENOSYS. What are you doing that would generate that?

This shows it’s supported.

[root@xmpp01 ~]# grep -i uring /boot/config-$(uname -r)
CONFIG_IO_URING=y
[root@xmpp01 ~]# grep io_uring_setup /proc/kallsyms
ffffffffa61d35c0 t __pfx_io_uring_setup
ffffffffa61d35d0 t io_uring_setup
ffffffffa61d3660 T __pfx___ia32_sys_io_uring_setup
ffffffffa61d3670 T __ia32_sys_io_uring_setup
ffffffffa61d36f0 T __pfx___x64_sys_io_uring_setup
ffffffffa61d3700 T __x64_sys_io_uring_setup
ffffffffa6816287 t io_uring_setup.cold
ffffffffa7cb0140 d event_exit__io_uring_setup
ffffffffa7cb01e0 d event_enter__io_uring_setup
ffffffffa7cb0280 d __syscall_meta__io_uring_setup
ffffffffa7cb02c0 d args__io_uring_setup
ffffffffa7cb02d0 d types__io_uring_setup
ffffffffa84b9aa8 d __event_exit__io_uring_setup
ffffffffa84b9ab0 d __event_enter__io_uring_setup
ffffffffa84bbb78 d __p_syscall_meta__io_uring_setup
ffffffffa84bfb10 d _eil_addr___ia32_sys_io_uring_setup
ffffffffa84bfb20 d _eil_addr___x64_sys_io_uring_setup

[root@xmpp01 ~]# cat ex.c
#include <errno.h>
#include <linux/io_uring.h>
#include <stddef.h>
#include <sys/syscall.h>
#include <unistd.h>
#include <stdio.h>

int main(int argc, char **argv) {
  if (syscall(__NR_io_uring_register, 0, IORING_UNREGISTER_BUFFERS, NULL, 0) && errno == ENOSYS) {
    printf("Not available\n");
  } else {
    printf("Available\n");
  }
}
[root@xmpp01 ~]# gcc -o test ex.c
[root@xmpp01 ~]# ./test
Available
5

It doesn’t seem to be a kernel issue. I’m running a test program inside a podman container and getting ENOSYS. Running it directly on the host does return 0.

6

This is most likely due to default limitations in docker containers for security reasons. There is something about it here: Allow containers access to `io_uring` syscalls · Issue #16796 · containers/podman · GitHub

Someone there suggests running the container with:

--security-opt seccomp=unconfined

alternatively as also suggested towards the end of the thread because of the security risks allowing everything using the above command, would require you to create your own seccomp.

7

More precisely, this is a security vulnerability in seccomp itself, which cannot filter system calls indirectly invoked by io_uring.

8

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