Do not update grub if grub not used

The security check should be skipped if GRUB update tool does not
exist (grub isn't installed).

Change-Id: I99a3b372e12e264cbc40bdc3ae6b6b60bf3c1c79
(cherry picked from commit 9361a146e4)

handlers/main.yml

@@ -74,6 +74,8 @@
   command: "{{ grub_update_cmd }}"
   when:
     - security_enable_grub_update | bool
+    - grub_update_binary.stat.exists | bool
+    - grub_update_binary.stat.executable | bool
   notify:
     - set bootloader file permissions after updating grub config
 

tasks/main.yml

@@ -45,4 +45,11 @@
     tags:
       - always
 
+  - name: Check if grub is present on the remote node
+    stat:
+      path: "{{ grub_update_cmd.split(' ')[0] }}"
+    register: grub_update_binary
+    tags:
+      - always
+
   - include: "{{ stig_version }}stig/main.yml"

vars/redhat.yml

@@ -39,7 +39,7 @@ chrony_service: chronyd
 clamav_service: 'clamd@scan'
 
 # Commands
-grub_update_cmd: "grub2-mkconfig -o {{ grub_config_file_boot }}"
+grub_update_cmd: "/usr/sbin/grub2-mkconfig -o {{ grub_config_file_boot }}"
 ssh_keysign_path: /usr/libexec/openssh
 
 # RHEL 6 STIG: Packages to add/remove

vars/ubuntu.yml

@@ -42,7 +42,7 @@ chrony_service: chrony
 clamav_service: clamav-daemon
 
 # Commands
-grub_update_cmd: "update-grub"
+grub_update_cmd: "/usr/sbin/update-grub"
 ssh_keysign_path: /usr/lib/openssh
 
 # RHEL 6 STIG: Packages to add/remove