SLE Micro - SELinux Relabeling Service runs at every reboot

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Environment

SLE Micro 5.2

Situation

SELinux is enabled but the SELinux relabeling service runs at every reboot.

slem:~ # cat /sys/kernel/security/lsm
lockdown,capability,selinux

slem:~ # systemd-analyze blame
31.541s \x2esnapshots-relabel.service
18.241s wicked.service
..

initrd detects a labeled system but disabled SELinux:

Sep 19 13:35:09 slem systemd[1]: Starting dracut pre-pivot and cleanup hook...
Sep 19 13:35:09 slem dracut-pre-pivot[435]: Warning: SElinux is off in lablelled system!

SELinux itself thinks it is enabled, so the selinux-relabel-generator runs

Sep 19 13:35:12 slem root[472]: SELinux relabel generator: selinux is enabled
Sep 19 13:35:12 slem root[473]: SELinux relabel generator: /etc/selinux/.autorelabel exist

Sep 19 13:35:13 slem systemd[1]: Successfully loaded SELinux policy in 2.093083s.
Sep 19 13:35:13 slem systemd[1]: Relabelled /dev, /dev/shm, /run, /sys/fs/cgroup in 106.786ms.

Resolution

1) Edit /etc/default/grub and add selinux=1 to GRUB_CMDLINE_LINUX_DEFAULT,

GRUB_CMDLINE_LINUX_DEFAULT="splash=silent swapaccount=1 apparmor=0 mitigations=auto quiet crashkernel=195M,high crashkernel=72M,low security=selinux selinux=1"

2) run:

transactional-update grub.cfg

3) reboot

Cause

For some reasons selinux=1 kernel parameter is missing in the GRUB 2 boot loader:

Sep 19 13:35:06 slem kernel: Command line: BOOT_IMAGE=/boot/vmlinuz-5.3.18-150300.59.93-default root=UUID=d14ddd02-01f3-4910-b9ff-bf38d1684a64 rd.timeout=60 splash=silent swapaccount=1 apparmor=0 mitigations=auto quiet crashkernel=195M,high crashkernel=72M,low security=selinux

Additional Information

Introduction to SELinux - https://documentation.suse.com/sle-micro/5.2/single-html/SLE-Micro-security/#sec-introduction-selinux

Disclaimer

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