`chattr +i` receives `Operation not permitted while setting flags` in pod with sysbox runtime.

[AidanAbd]

Hi @ctalledo,

I am trying to get chattr +i filename working in a sysbox pod with the following definition:

apiVersion: v1
kind: Pod
metadata:
  name: aidan-test-some-things
  annotations:
    io.kubernetes.cri-o.userns-mode: "auto:size=65536"
spec:
  runtimeClassName: sysbox-runc
  containers:
  - name: ubu-bio-systemd-docker
    image: registry.nestybox.com/nestybox/ubuntu-bionic-systemd-docker
    command: ["/sbin/init"]
  restartPolicy: Never

Inside the pod I see the capability cap_linux_immutable (I configured crio to add this capability to the default set), and a full capability set as expected. However, when running chattr +i on a file, I get the following error:

root@aidan-test-some-things:~# touch test.txt
root@aidan-test-some-things:~# ls -la
total 16
drwx------ 1 root root 4096 Aug 19 21:19 .
dr-xr-xr-x 1 root root 4096 Aug 19 21:18 ..
-rw-r--r-- 1 root root 3106 Apr  9  2018 .bashrc
-rw-r--r-- 1 root root  148 Aug 17  2015 .profile
-rw-r--r-- 1 root root    0 Aug 19 21:19 test.txt
root@aidan-test-some-things:~# chattr +i test.txt
chattr: Operation not permitted while setting flags on test.txt

I have this same behavior on linux kernel 6.5.0 + k8s 1.29 + sysbox 0.6.4 and with linux kernel 5.15.0 + k8s 1.28 + sysbox 0.6.4. The outputs here are from the latter but they are nearly identical.

I have attached the strace output and the crio config to this issue. Let me know any other information that would be helpful or if I am missing something.

strace.txt crio-config.txt

[AidanAbd]

Hey @ctalledo @rodnymolina, could I get a status update here? If y'all do not have time to look into it, I can start building from source and testing but this has become high priority for us.

[rodnymolina]

Hi @AidanAbd, sorry for the delay in getting back to you.

I don't think you need to add any capabilities to CRIO's config since Sysbox enables them all to the init-process of every container.

Now, the issue that you are reporting doesn't seem trivial to me since we are getting an EPERM from the kernel while trying to execute that IOCTL that we see in the strace.

I went ahead and reproduced this issue in my own setup (regular docker+sysbox env), so there's nothing k8s-specific here. We'll need to look at this one in more details since I'm not sure why is the kernel complaining.

[AidanAbd]

Sounds good. Excited for any updates but understand this one might take a bit longer.