Use OpenDKIM instead of rmilter for DKIM

As part of #61 this moves DKIM handling from rmilter to OpenDKIM.

default.nix

@@ -733,6 +733,7 @@ in
     ./mail-server/networking.nix
     ./mail-server/systemd.nix
     ./mail-server/dovecot.nix
+    ./mail-server/opendkim.nix
     ./mail-server/postfix.nix
     ./mail-server/rmilter.nix
     ./mail-server/nginx.nix

mail-server/opendkim.nix

@@ -0,0 +1,90 @@
+#  nixos-mailserver: a simple mail server
+#  Copyright (C) 2017  Brian Olsen
+#
+#  This program is free software: you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License as published by
+#  the Free Software Foundation, either version 3 of the License, or
+#  (at your option) any later version.
+#
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with this program. If not, see <http://www.gnu.org/licenses/>
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.mailserver;
+
+  dkimUser = config.services.opendkim.user;
+  dkimGroup = config.services.opendkim.group;
+
+  createDomainDkimCert = dom:
+    let
+      dkim_key = "${cfg.dkimKeyDirectory}/${dom}.${cfg.dkimSelector}.key";
+      dkim_txt = "${cfg.dkimKeyDirectory}/${dom}.${cfg.dkimSelector}.txt";
+    in
+        ''
+          if [ ! -f "${dkim_key}" ] || [ ! -f "${dkim_txt}" ]
+          then
+              ${pkgs.opendkim}/bin/opendkim-genkey -s "${cfg.dkimSelector}" \
+                                                   -d "${dom}" \
+                                                   --directory="${cfg.dkimKeyDirectory}"
+              mv "${cfg.dkimKeyDirectory}/${cfg.dkimSelector}.private" "${dkim_key}"
+              mv "${cfg.dkimKeyDirectory}/${cfg.dkimSelector}.txt" "${dkim_txt}"
+              echo "Generated key for domain ${dom} selector ${cfg.dkimSelector}"
+          fi
+        '';
+  createAllCerts = lib.concatStringsSep "\n" (map createDomainDkimCert cfg.domains);
+  create_dkim_cert =
+        ''
+          # Create dkim dir
+          mkdir -p "${cfg.dkimKeyDirectory}"
+          chown ${dkimUser}:${dkimGroup} "${cfg.dkimKeyDirectory}"
+
+          ${createAllCerts}
+
+          chown -R ${dkimUser}:${dkimGroup} "${cfg.dkimKeyDirectory}"
+        '';
+
+  keyTable = pkgs.writeText "opendkim-KeyTable" 
+    (lib.concatStringsSep "\n" (lib.flip map cfg.domains 
+      (dom: "${dom} ${dom}:${cfg.dkimSelector}:${cfg.dkimKeyDirectory}/${dom}.${cfg.dkimSelector}.key")));
+  signingTable = pkgs.writeText "opendkim-SigningTable" 
+    (lib.concatStringsSep "\n" (lib.flip map cfg.domains (dom: "${dom} ${dom}")));
+
+  dkim = config.services.opendkim;
+  args = [ "-f" "-l" ] ++ lib.optionals (dkim.configFile != null) [ "-x" dkim.configFile ];
+in
+{
+    config = mkIf (cfg.dkimSigning && cfg.enable) {
+      services.opendkim = {
+        enable = true;
+        selector = cfg.dkimSelector;
+        domains = "csl:${builtins.concatStringsSep "," cfg.domains}";
+        configFile = pkgs.writeText "opendkim.conf" (''
+          Canonicalization relaxed/simple
+          UMask 0002
+          Socket ${dkim.socket}
+          KeyTable file:${keyTable}
+          SigningTable file:${signingTable}
+        '' + (lib.optionalString cfg.debug ''
+          Syslog yes
+          SyslogSuccess yes
+          LogWhy yes
+        ''));
+      };
+
+      users.users = optionalAttrs (config.services.postfix.user == "postfix") {
+        postfix.extraGroups = [ "${config.services.opendkim.group}" ];
+      };
+      systemd.services.opendkim = {
+        preStart = create_dkim_cert;
+        serviceConfig.ExecStart = lib.mkForce "${pkgs.opendkim}/bin/opendkim ${escapeShellArgs args}";
+      };
+    };
+}

mail-server/postfix.nix

@@ -90,6 +90,17 @@ let
 
      /^Message-ID:\s+<(.*?)@.*?>/ REPLACE Message-ID: <$1@${cfg.fqdn}>
   '');
+
+  inetSocket = addr: port: "inet:[${toString port}@${addr}]";
+  unixSocket = sock: "unix:${sock}";
+
+  rmilter = config.services.rmilter;
+  rmilterSocket = if rmilter.bindSocket.type == "unix" then unixSocket rmilter.bindSocket.path
+    else inetSocket rmilter.bindSocket.address rmilter.bindSocket.port;
+
+  smtpdMilters =
+   (lib.optional cfg.dkimSigning "unix:/run/opendkim/opendkim.sock")
+   ++ [ rmilterSocket ];
 in
 {
   config = with cfg; lib.mkIf enable {
@@ -151,6 +162,11 @@ in
 
         # Configure a non blocking source of randomness
         tls_random_source = dev:/dev/urandom
+
+        smtpd_milters = ${lib.concatStringsSep "," smtpdMilters}
+        ${lib.optionalString cfg.dkimSigning "non_smtpd_milters = unix:/run/opendkim/opendkim.sock"}
+        milter_protocol = 6
+        milter_mail_macros = i {mail_addr} {client_addr} {client_name} {auth_type} {auth_authen} {auth_author} {mail_addr} {mail_host} {mail_mailer}
       '';
 
       submissionOptions =

mail-server/rmilter.nix

@@ -27,23 +27,8 @@ let
              };
            ''
            else "";
-  dkim = if cfg.dkimSigning
+  postfixCfg = config.services.postfix;
-  # Note: domain = "*"; causes Rmilter to try to search key in the key path
+  rmilter = config.services.rmilter;
-  # as keypath/domain.selector.key for any domain.
-         then
-         ''
-            dkim {
-              domain {
-                key = "${cfg.dkimKeyDirectory}";
-                domain = "*";
-                selector = "${cfg.dkimSelector}";
-              };
-              sign_alg = sha256;
-              auth_only = yes;
-              header_canon = relaxed;
-            }
-         ''
-         else "";
 in
 {
   config = with cfg; lib.mkIf enable {
@@ -54,7 +39,6 @@ in
     services.rmilter = {
       inherit debug;
       enable = true;
-      postfix.enable = true;
       rspamd = {
         enable = true;
         extraConfig = "extended_spam_headers = yes;";
@@ -65,10 +49,9 @@ in
       max_size = 20M;
 
       ${clamav}
-
-      ${dkim}
       '';
     };
+    users.extraUsers.${postfixCfg.user}.extraGroups = [ rmilter.group ];
   };
 }
 

mail-server/systemd.nix

@@ -19,33 +19,6 @@
 let
   cfg = config.mailserver;
 
-  createDomainDkimCert = dom:
-    let
-      dkim_key = "${cfg.dkimKeyDirectory}/${dom}.${cfg.dkimSelector}.key";
-      dkim_txt = "${cfg.dkimKeyDirectory}/${dom}.${cfg.dkimSelector}.txt";
-    in
-        ''
-          if [ ! -f "${dkim_key}" ] || [ ! -f "${dkim_txt}" ]
-          then
-              ${pkgs.opendkim}/bin/opendkim-genkey -s "${cfg.dkimSelector}" \
-                                                   -d "${dom}" \
-                                                   --directory="${cfg.dkimKeyDirectory}"
-              mv "${cfg.dkimKeyDirectory}/${cfg.dkimSelector}.private" "${dkim_key}"
-              mv "${cfg.dkimKeyDirectory}/${cfg.dkimSelector}.txt" "${dkim_txt}"
-          fi
-        '';
-  createAllCerts = lib.concatStringsSep "\n" (map createDomainDkimCert cfg.domains);
-  create_dkim_cert =
-        ''
-          # Create dkim dir
-          mkdir -p "${cfg.dkimKeyDirectory}"
-          chown rmilter:rmilter "${cfg.dkimKeyDirectory}"
-
-          ${createAllCerts}
-
-          chown -R rmilter:rmilter "${cfg.dkimKeyDirectory}"
-        '';
-
   createDhParameterFile = let
      dovecotVersion = builtins.fromJSON
        (builtins.readFile (pkgs.callPackage ./dovecot-version.nix {}));
@@ -121,19 +94,16 @@ in
 
     # Postfix requires rmilter socket, dovecot lmtp socket, dovecot auth socket and certificate to work
     systemd.services.postfix = {
-      after = [ "rmilter.socket" "dovecot2.service" "mailserver-certificates.target" ];
+      after = [ "rmilter.socket" "dovecot2.service" "mailserver-certificates.target" ]
+        ++ (lib.optional cfg.dkimSigning "opendkim.service");
       wants = [ "mailserver-certificates.target" ];
-      requires = [ "rmilter.socket" "dovecot2.service" ];
+      requires = [ "rmilter.socket" "dovecot2.service" ]
+        ++ (lib.optional cfg.dkimSigning "opendkim.service");
     };
 
-    # Create dkim certificates
     systemd.services.rmilter = {
       requires = [ "rmilter.socket" ];
       after = [ "rmilter.socket" ];
-      preStart =
-      ''
-        ${create_dkim_cert}
-      '';
     };
   };
 }

tests/extern.nix

@@ -23,6 +23,14 @@ import <nixpkgs/nixos/tests/make-test.nix> {
                 ../default.nix
             ];
 
+            services.rsyslogd = {
+              enable = true;
+              defaultConfig = ''
+              *.*   /dev/console
+              '';
+            };
+
+
             mailserver = {
               enable = true;
               debug = true;