roles/common: Add Spamhaus DROP lists to firewalld ipsets

This configures the recommended DROP, EDROP, and DROPv6 lists from
Spamhaus as ipsets in firewalld. First we copy an empty placeholder
ipset to seed firewalld, then we use a shell script to download the
real lists and activate them. The same shell script is run daily as
a service (update-spamhaus-lists.service) by a systemd timer.

I am strictly avoiding any direct ipset commands here because I want
to make sure that this works on older hosts where ipsets is used as
well as newer hosts that have moved to nftables such as Ubuntu 20.04.
So far I have tested this on Ubuntu 16.04, 18.04, and 20.04, but ev-
entually I need to abstract the tasks and run them on CentOS 7+ as
well.

See: https://www.spamhaus.org/drop/

roles/common/tasks/firewall_Ubuntu.yml

@@ -54,6 +54,32 @@
     loop:
       - abusers-ipv4.xml
       - abusers-ipv6.xml
+      - spamhaus-ipv4.xml
+      - spamhaus-ipv6.xml
+    notify:
+      - restart firewalld
+
+  - name: Copy Spamhaus update script
+    when: ansible_distribution_version is version('16.04', '>=')
+    copy: src=update-spamhaus-lists.sh dest=/usr/local/bin/update-spamhaus-lists.sh mode=0755 owner=root group=root
+
+  - name: Copy Spamhaus systemd units
+    when: ansible_distribution_version is version('16.04', '>=')
+    copy: src={{ item }} dest=/etc/systemd/system/{{ item }} mode=0644 owner=root group=root
+    loop:
+        - update-spamhaus-lists.service
+        - update-spamhaus-lists.timer
+    register: spamhaus_systemd_units
+
+  # need to reload to pick up service/timer/environment changes
+  - name: Reload systemd daemon
+    systemd: daemon_reload=yes
+    when: spamhaus_systemd_units is changed
+
+  - name: Start and enable Spamhaus update timer
+    when: ansible_distribution_version is version('16.04', '>=')
+    systemd: name=update-spamhaus-lists.timer state=started enabled=yes
+
     notify:
       - restart firewalld