livemedia-creator: Check selinux state and exit

lmc --no-virt was switching selinux to permissive if it was enforcing
and restore it when done. This works fine when it is the only session
running, but would cause problems if it was run in parallel.

It now only checks the state and exits with an error if it isn't already
disabled or in Permissive mode.

Users will need to run setenforce 0 before running lmc.

src/sbin/livemedia-creator

@@ -32,6 +32,7 @@ import glob
 import json
 from math import ceil
 import socket
+import selinux
 
 # Use pykickstart to calculate disk image size
 from pykickstart.parser import KickstartParser
@@ -663,19 +664,11 @@ def novirt_install(opts, disk_img, disk_size):
     :param str disk_img: The full path to the disk image to be created
     :param int disk_size: The size of the disk_img in MiB
 
-    This method makes sure SELinux is permissive during the install, runs anaconda
-    to create the image and then based on the opts passed create a qemu disk image
-    or tarfile.
+    This method runs anaconda to create the image and then based on the opts
+    passed creates a qemu disk image or tarfile.
     """
-    import selinux
     dirinstall_path = ROOT_PATH
 
-    # Set selinux to Permissive if it is Enforcing
-    selinux_enforcing = False
-    if selinux.is_selinux_enabled() and selinux.security_getenforce():
-        selinux_enforcing = True
-        selinux.security_setenforce(0)
-
     # Clean up /tmp/ from previous runs to prevent stale info from being used
     for path in ["/tmp/yum.repos.d/", "/tmp/yum.cache/"]:
         if os.path.isdir(path):
@@ -763,9 +756,6 @@ def novirt_install(opts, disk_img, disk_size):
                 dm_detach(dm_path)
                 loop_detach(get_loop_name(disk_img))
 
-        if selinux_enforcing:
-            selinux.security_setenforce(1)
-
     # qemu disk image is used by bare qcow2 images and by Vagrant
     if opts.image_type:
         log.info("Converting %s to %s", disk_img, opts.image_type)
@@ -1153,6 +1143,10 @@ def main():
        and not os.path.exists("/usr/sbin/anaconda"):
         errors.append("no-virt requires anaconda to be installed.")
 
+    if is_install and opts.no_virt:
+        if selinux.is_selinux_enabled() and selinux.security_getenforce():
+            errors.append("selinux must be disabled or in Permissive mode.")
+
     if opts.make_appliance and not opts.app_template:
         opts.app_template = joinpaths(opts.lorax_templates,
                                             "appliance/libvirt.tmpl")