IMAP: Update role to Debian Buster.

For `ssl_cipher_list` we pick the suggested value from
https://ssl-config.mozilla.org/#server=dovecot&version=2.3.9&config=intermediate&openssl=1.1.1d

At the moment it's equivalent (modulo order) to adding ‘EDH+AESGCM+aRSA’
to ‘EECDH+AESGCM:EECDH+CHACHA20!MEDIUM!LOW!EXP!aNULL!eNULL’.

1 files changed, 22 insertions, 11 deletions

diff --git a/roles/IMAP/files/etc/dovecot/conf.d/10-ssl.conf b/roles/IMAP/files/etc/dovecot/conf.d/10-ssl.conf
index 209347f..adeb879 100644
--- a/roles/IMAP/files/etc/dovecot/conf.d/10-ssl.conf
+++ b/roles/IMAP/files/etc/dovecot/conf.d/10-ssl.conf
@@ -10,53 +10,64 @@ ssl = required
 # root. Included doc/mkcert.sh can be used to easily generate self-signed
 # certificate, just make sure to update the domains in dovecot-openssl.cnf
 ssl_cert = </etc/dovecot/ssl/imap.fripost.org.pem
 ssl_key = </etc/dovecot/ssl/imap.fripost.org.key
 
 # If key file is password protected, give the password here. Alternatively
 # give it when starting dovecot with -p parameter. Since this file is often
 # world-readable, you may want to place this setting instead to a different
 # root owned 0600 file by using ssl_key_password = <path.
 #ssl_key_password =
 
 # PEM encoded trusted certificate authority. Set this only if you intend to use
 # ssl_verify_client_cert=yes. The file should contain the CA certificate(s)
 # followed by the matching CRL(s). (e.g. ssl_ca = </etc/ssl/certs/ca.pem)
 #ssl_ca =
 
 # Require that CRL check succeeds for client certificates.
 #ssl_require_crl = yes
 
 # Directory and/or file for trusted SSL CA certificates. These are used only
-# when Dovecot needs to act as an SSL client (e.g. imapc backend). The
-# directory is usually /etc/ssl/certs in Debian-based systems and the file is
-# /etc/pki/tls/cert.pem in RedHat-based systems.
-#ssl_client_ca_dir =
+# when Dovecot needs to act as an SSL client (e.g. imapc backend or
+# submission service). The directory is usually /etc/ssl/certs in
+# Debian-based systems and the file is /etc/pki/tls/cert.pem in
+# RedHat-based systems.
+ssl_client_ca_dir = /etc/ssl/certs
 #ssl_client_ca_file =
 
 # Request client to send a certificate. If you also want to require it, set
 # auth_ssl_require_client_cert=yes in auth section.
 #ssl_verify_client_cert = no
 
 # Which field from certificate to use for username. commonName and
 # x500UniqueIdentifier are the usual choices. You'll also need to set
 # auth_ssl_username_from_cert=yes.
 #ssl_cert_username_field = commonName
 
-# DH parameters length to use.
-ssl_dh_parameters_length = 2048
+# SSL DH parameters
+# Generate new params with `openssl dhparam -out /etc/dovecot/dh.pem 4096`
+# Or migrate from old ssl-parameters.dat file with the command dovecot
+# gives on startup when ssl_dh is unset.
+ssl_dh = </etc/ssl/dhparams.pem
 
-# SSL protocols to use
-#ssl_protocols = !SSLv3
+# Minimum SSL protocol version to use. Potentially recognized values are SSLv3,
+# TLSv1, TLSv1.1, and TLSv1.2, depending on the OpenSSL version used.
+ssl_min_protocol = TLSv1.2
 
 # SSL ciphers to use
-ssl_cipher_list = EECDH+AESGCM:EECDH+CHACHA20!MEDIUM!LOW!EXP!aNULL!eNULL
+ssl_cipher_list = 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
+
+# Colon separated list of elliptic curves to use. Empty value (the default)
+# means use the defaults from the SSL library. P-521:P-384:P-256 would be an
+# example of a valid value.
+#ssl_curve_list =
 
 # Prefer the server's order of ciphers over client's.
 #ssl_prefer_server_ciphers = no
 
 # SSL crypto device to use, for valid values run "openssl engine"
 #ssl_crypto_device =
 
 # SSL extra options. Currently supported options are:
-#   no_compression - Disable compression.
-ssl_options = no_compression
+#   compression - Enable compression.
+#   no_ticket - Disable SSL session tickets.
+#ssl_options =