Unblock security role gate

This patch addresses two issues that are blocking the security role
CI jobs from completing:

The OpenStack CI image is missing the default audit.rules file and this
causes augenrules to fail when it loads new rules. The first line in
the default rules file deletes existing rules and this must be in
place before loading new rulesets. The contents of the default file
are now in the template file, which is safer anyway. The default
file provided by the OS is removed.

The task that updates the apt cache in test.yml was running more than
once during the CI job run when the gate ran slowly. That's fine, but
it breaks the idempotence checks. A `changed_when` is added to the task
to ensure that the idempotence tests aren't affected by an apt cache
update.

Change-Id: I9c2b50389cc2e4fa81717dcceccf6da1d973d34c

tasks/rhel6stig/auditd.yml

@@ -243,6 +243,15 @@
     - cat2
     - V-38498
 
+- name: Remove system default audit.rules file
+  file:
+    path: /etc/audit/rules.d/audit.rules
+    state: absent
+  notify:
+    - generate auditd rules
+  tags:
+    - always
+
 - name: Auditd rules (includes several STIGs)
   template:
     src: osas-auditd.j2

tasks/rhel7stig/auditd.yml

@@ -29,7 +29,6 @@
   tags:
     - always
 
-
 - name: RHEL-07-030330 - The operating system must off-load audit records onto a different system or media from the system being audited
   lineinfile:
     dest: /etc/audisp/audisp-remote.conf
@@ -67,6 +66,17 @@
   tags:
     - always
 
+- name: Remove system default audit.rules file
+  file:
+    path: /etc/audit/rules.d/audit.rules
+    state: absent
+  when:
+    - auditd_conf.stat.exists
+  notify:
+    - generate auditd rules
+  tags:
+    - always
+
 - name: Remove old RHEL 6 audit rules file
   file:
     path: /etc/audit/rules.d/osas-auditd.rules

templates/osas-auditd-rhel7.j2

@@ -5,6 +5,16 @@
 #
 #    http://docs.openstack.org/developer/openstack-ansible-security/
 #
+
+# Delete all existing auditd rules prior to loading this ruleset.
+-D
+
+# Increase the buffers to survive stress events.
+-b 320
+
+# Set the auditd failure flag.
+-f {{ security_rhel7_audit_failure_flag }}
+
 {#                                                                           #}
 {# The following loop takes a variable called audited_commands (a list of    #}
 {# dictionaries) and creates audit rules for each audited command or         #}
@@ -85,6 +95,3 @@
 -w /etc/shadow -p wa -k RHEL-07-030710
 -w /etc/security/opasswd -p wa -k RHEL-07-030710
 {% endif %}
-
-# Set the auditd failure flag
--f {{ security_rhel7_audit_failure_flag }}

templates/osas-auditd.j2

@@ -1,5 +1,11 @@
 # {{ ansible_managed }}
 
+# Delete all existing auditd rules prior to loading this ruleset.
+-D
+
+# Increase the buffers to survive stress events.
+-b 320
+
 {% if security_audit_clock_settimeofday | bool %}
 # RHEL 6 STIG V-38522
 # Audits changes to system time via settimeofday

tests/test.yml

@@ -21,6 +21,7 @@
         update_cache: yes
         cache_valid_time: "{{ cache_timeout }}"
       when: ansible_pkg_mgr == 'apt'
+      changed_when: False
     - name: Ensure OpenStack CI image has a logrotate cron job
       file:
         path: /etc/cron.daily/logrotate