dovecot: preset-based tls config, new presets, buster compat

dovecot/defaults/main.yml

@@ -14,9 +14,10 @@ dovecot_max_uid: 0
 dovecot_tls_cert: /etc/ssl/private/fullchain.pem
 dovecot_tls_key: /etc/ssl/private/privkey.pem
 dovecot_tls_ca_dir: /etc/ssl/certs
-dovecot_tls_ciphers: "{{ tls_ciphers }}"
-dovecot_tls_dh_length: 4096
-dovecot_tls_protocols: 'TLSv1.1 TLSv1.2 !SSLv3'
+
+# possible values: modern, intermediate, old, previous
+# see also: https://ssl-config.mozilla.org/
+dovecot_tls_configuration: 'previous'
 
 dovecot_dsync: false
 dovecot_dsync_tls: false

dovecot/tasks/main.yml

 ---
 
+- name: "include tls config vars (preset: {{ dovecot_tls_configuration }})"
+  include_vars:
+    file: "tls-{{ dovecot_tls_configuration }}.yml"
+  tags:
+    - dovecot
+    - mail
+
 - name: ensure all required dovecot packages are installed
   apt:
     name:
@@ -36,6 +43,20 @@
     - dovecot
     - mail
 
+- name: ensure dh params are available
+  copy:
+    src: "{{ dovecot_tls_dh_file }}"
+    dest: /etc/dovecot/dh.pem
+    owner: root
+    group: root
+    mode: '0644'
+  when: dovecot_tls_dh_file is string
+  notify:
+    - restart dovecot
+  tags:
+    - dovecot
+    - mail
+
 - name: ensure there is a folder for global sieve scripts
   file:
     dest: /var/lib/dovecot/sieve.d

dovecot/templates/conf.d/10-ssl.conf.j2

@@ -42,18 +42,39 @@ ssl_client_ca_dir = {{ dovecot_tls_ca_dir }}
 # auth_ssl_username_from_cert=yes.
 #ssl_cert_username_field = commonName
 
+{% if ansible_distribution_major_version|int < 10 %}
 # DH parameters length to use.
+{% if dovecot_tls_dh_length %}
 ssl_dh_parameters_length = {{ dovecot_tls_dh_length }}
+{% else %}
+#ssl_dh_parameters_length =
+{% endif %}
+{% else %}
+# DH parameters to use.
+{% if dovecot_tls_dh_file %}
+ssl_dh = </etc/dovecot/dh.pem
+{% else %}
+#ssl_dh =
+{% endif %}
+{% endif %}
 
+{% if ansible_distribution_major_version|int < 10 %}
 # SSL protocols to use
 ssl_protocols = {{ dovecot_tls_protocols }}
+{% else %}
+# Minimum TLS version to use
+ssl_min_protocol = {{ dovecot_tls_min_protocol }}
+{% endif %}
 
 # SSL ciphers to use
-#ssl_cipher_list = HIGH:!LOW:!SSLv2:!EXP:!aNULL:!MD5:!RC4:!SHA1
+{% if dovecot_tls_ciphers %}
 ssl_cipher_list = {{ dovecot_tls_ciphers }}
+{% else %}
+#ssl_cipher_list =
+{% endif %}
 
 # Prefer the server's order of ciphers over client's.
-ssl_prefer_server_ciphers = yes
+ssl_prefer_server_ciphers = {{ 'yes' if dovecot_tls_prefer_server_ciphers else 'no' }}
 
 # SSL crypto device to use, for valid values run "openssl engine"
 #ssl_crypto_device =

dovecot/vars/tls-intermediate.yml

+---
+
+dovecot_tls_protocols: 'TLSv1.2 TLSv1.3'
+dovecot_tls_min_protocol: 'TLSv1.2'
+dovecot_tls_ciphers: 'ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384'
+dovecot_tls_dh_length: 4096 # 2048
+dovecot_tls_dh_file: ffdhe4096.txt # ffdhe2048.txt
+dovecot_tls_prefer_server_ciphers: false

dovecot/vars/tls-modern.yml

+---
+
+dovecot_tls_protocols: 'TLSv1.3'
+dovecot_tls_min_protocol: 'TLSv1.3'
+dovecot_tls_ciphers: null
+dovecot_tls_dh_length: null
+dovecot_tls_dh_file: null
+dovecot_tls_prefer_server_ciphers: false

dovecot/vars/tls-old.yml

+---
+
+dovecot_tls_protocols: 'TLSv1 TLSv1.1 TLSv1.2 !SSLv3'
+dovecot_tls_min_protocol: 'TLSv1'
+dovecot_tls_ciphers: 'ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:DHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA:ECDHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES256-SHA256:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA:DES-CBC3-SHA'
+dovecot_tls_dh_length: 2048 # 1024
+dovecot_tls_dh_file: ffdhe2048.txt # openssl dhparam 1024 > ffdhe1024.txt
+dovecot_tls_prefer_server_ciphers: true

dovecot/vars/tls-previous.yml

+---
+
+dovecot_tls_protocols: 'TLSv1.1 TLSv1.2 !SSLv3'
+dovecot_tls_min_protocol: 'TLSv1.1'
+dovecot_tls_ciphers: "{{ tls_ciphers }}"
+dovecot_tls_dh_length: 4096
+dovecot_tls_dh_file: ffdhe4096.txt # ffdhe2048.txt
+dovecot_tls_prefer_server_ciphers: true