Use StandardInput=tty when AUTORELABEL=0

selinux-autorelabel service can be configured to drop to a shell to allow
administrator to manually relabel a filesystem, see selinux_config(5). In
this case, the service needs to have a tty attached to stdin. Given that
tty should not be attached to the service by default, see
https://bugzilla.redhat.com/show_bug.cgi?id=1634661 , the
selinux-autorelabel-generator.sh will configure the service to attach
tty only if AUTORELABEL=0

Resolves: rhbz#2165508

selinux-autorelabel-generator.sh

@@ -18,6 +18,15 @@ fi
 set_target ()
 {
     ln -sf "$unitdir/selinux-autorelabel.target" "$earlydir/default.target"
+    AUTORELABEL="1"
+    source /etc/selinux/config
+    if [ "$AUTORELABEL" = "0" ]; then
+        mkdir -p "$earlydir/selinux-autorelabel.service.d"
+        cat > "$earlydir/selinux-autorelabel.service.d/tty.conf" <<EOF
+[Service]
+StandardInput=tty
+EOF
+    fi
 }
 
 if selinuxenabled; then