Improve the detection of SELinux capable rootfs

initramfs uses tmpfs regardless of whether root=tmpfs in Warewulf. As
such, 90-selinux needs to be updated to detect the actual provenance of
/, rather than the configured setting.

Signed-off-by: Jonathon Anderson <janderson@ciq.com>

CHANGELOG.md

@@ -48,6 +48,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Replace reference to docusaurus with Sphinx
 - `wwctl container import` now only runs syncuser if explicitly requested. #1212
 - wwinit now configures NetworkManager to not retain configurations from dracut. #1115
+- Improved detection of SELinux capable root fs #1093
 
 ### Fixed
 

overlays/wwinit/rootfs/warewulf/init.d/90-selinux

@@ -2,11 +2,6 @@
 
 . /warewulf/config
 
-if test -z "$WWROOT"; then
-    echo "Skipping SELinux configuration: Warewulf Root device not set"
-    exit
-fi
-
 if test -f "/etc/sysconfig/selinux"; then
     . /etc/sysconfig/selinux
 else
@@ -14,22 +9,25 @@ else
     exit
 fi
 
-if test "$WWROOT" == "initramfs"; then
-    echo "Skipping SELinux configuration: 'Root=initramfs'"
-    if test "$SELINUX" != "disabled"; then
-        echo "WARNING: SELinux prep is being skipped, but SELinux is enabled on host! This may"
-        echo "WARNING: cause the system to not work properly. Try setting 'Root=tmpfs'"
-        sleep 5
-    fi
+if test "$SELINUX" == "disabled"; then
+    echo "Skipping SELinux setup per /etc/sysconfig/selinux"
     exit
 fi
 
-if test "$SELINUX" == "disabled"; then
-    echo "Skipping SELinux setup per /etc/sysconfig/selinux"
-elif grep -q "selinux=0" /proc/cmdline; then
+if grep -q "selinux=0" /proc/cmdline; then
     echo "Skipping SELinux setup per kernel command line"
-else
-    echo "Setting up SELinux"
-    /sbin/load_policy -i
-    /sbin/restorecon -r /
+    exit
 fi
+
+if [ $(findmnt / --noheadings --output SOURCE) == 'rootfs' ]; then
+    echo "Skipping SELinux configuration: rootfs does not support SELinux contexts"
+    echo
+    echo "WARNING: SELinux prep is being skipped, but SELinux is enabled on host! This may"
+    echo "WARNING: cause the system to not work properly. Try setting 'Root=tmpfs'"
+    sleep 5
+    exit
+fi
+
+echo "Setting up SELinux"
+/sbin/load_policy -i
+/sbin/restorecon -e /sys -r /