[Podman] Re: fs.mqueue.msg_max rootless problem

Hi, I think this is the same thing I raised in https://github.com/containers/podman/discussions/19737? This seems to be a kernel limitation - I'm not sure where the mqueue limits come from when creating a new IPC namespace, but it doesn't inherit the limits from the parent namespace and the root user within the user namespace does not have permissions to modify the limits. This was supposedly fixed in a recent kernel version although I haven't tested it. The workaround I'm currently using (requiring sudo permissions) is along the lines of: podman create --ipc private --name ctr_foo ... podman init ctr_foo ctr_pid=$(podman inspect -f '{{.State.Pid}}' ctr_foo) sudo nsenter --target $ctr_pid --user --ipc sysctl fs.mqueue.msg_max=64 podman start ctr_foo Obviously this isn't ideal, and I'd be open to alternatives... Regards, Lewis On Mon, 27 Nov 2023 at 12:23, Daniel Walsh <dwalsh(a)redhat.com&gt; wrote: On 11/27/23 02:04, Михаил Иванов wrote: > Hallo, > > For me rootful works: > > island:container [master]> cat /proc/sys/fs/mqueue/msg_max > 256 $ podman run alpine ls -ld /proc/sys/fs/mqueue/msg_max -rw-r--r--    1 nobody   nobody           0 Nov 27 12:10 /proc/sys/fs/mqueue/msg_max Since it is owned by real root, a rootless user can not write to it.  I guess we could ague this is a bug with the kernel. mqeueu/msg_max should be owned by root of the user namespace as opposed to real root. > ## Rootful: > island:container [master]> sudo podman run --sysctl=fs.mqueue.msg_max=64 --rm centos cat /proc/sys/fs/mqueue/msg_max > 64 > > ## Rootless: > island:container [master]> podman run --sysctl=fs.mqueue.msg_max=64 --rm centos cat /proc/sys/fs/mqueue/msg_max > Error: crun: open `/proc/sys/fs/mqueue/msg_max`: Permission denied: OCI permission denied > > ## What rootless gets by default (changed as compared to host setting!): > island:container [master]> podman run --rm centos cat /proc/sys/fs/mqueue/msg_max > 10 > > Rgrds, > On 25.11.2023 20:17, Daniel Walsh wrote: >> On 11/25/23 10:44, Михаил Иванов wrote: >>> Hallo, >>> Is it possible to get podman to propagate current host fs.mqueue.msg_max >>> value to rootless container? I can do that if I specify --ipc host when >>> running the container, but this also exposes other ipc stuff from host >>> to container, including shared memory, which I do not want. >>> >>> If I specify --sysctl fs.mqueue.msg_size=64 to podman it gives me >>> "OCI permission denied" error, even when my host setting (256) is greater >>> than requested value. >>> Thanks, >>> -- >>> Micvhael Ivanov >>> >>> _______________________________________________ >>> Podman mailing list --podman(a)lists.podman.io >>> To unsubscribe send an email topodman-leave(a)lists.podman.io >> >> The way you attempted is correct. Might not be allowed for >> rootless containers. >> >> I attempted this in a rootful container and it blows up for me. >> >> >> podman run  --sysctl fs.mqueue.msg_size=64 alpine echo hi >> Error: crun: open `/proc/sys/fs/mqueue/msg_size`: No such file >> or directory: OCI runtime attempted to invoke a command that was >> not found >> >> >> _______________________________________________ >> Podman mailing list --podman(a)lists.podman.io >> To unsubscribe send an email topodman-leave(a)lists.podman.io _______________________________________________ Podman mailing list -- podman(a)lists.podman.io To unsubscribe send an email to podman-leave(a)lists.podman.io