Add mail forwarding based on alias files

flake-module.nix

@@ -53,6 +53,12 @@
     _module.args.pkgs = import inputs.nixpkgs {
       inherit system;
       config.permittedInsecurePackages = ["jitsi-meet-1.0.8043"];
+
+      overlays = [
+        (_: _: {
+          alias-to-sieve = inputs.alias-to-sieve.packages.x86_64-linux.default; # add custom package to convert alias files to sieve scripts on the stalwart machine
+        })
+      ];
     };
   };
 

nixos/machines/kaalut/configuration.nix

@@ -12,6 +12,28 @@
     enable = true;
     # see passwd on azathoth for plaintext or machine secret in encoded format for HTTP Basic AUTH
     stalwartAdminHash = "$argon2i$v=19$m=4096,t=3,p=1$d0hYOTkzclpzSmFTZUplWnhVeWE$I7q9uB19RWL0oZKaPlMPSlGfFp6FQ/vrx80FFKCsalg";
+    domains = [
+      # lists.mathebau.de is forwarded to another VM and does not need to be listed here.
+      {
+        domain = "matheball.de";
+        allowlistPass = config.sops.secrets."allowlistPass/matheball".path;
+      }
+      {
+        domain = "mathebau.de";
+        allowlistPass = config.sops.secrets."allowlistPass/mathebau".path;
+        virt_aliases = config.sops.secrets."mathebau.aliases".path;
+      }
+      {
+        domain = "mathechor.de";
+        allowlistPass = config.sops.secrets."allowlistPass/mathechor".path;
+        virt_aliases = config.sops.secrets."mathechor.aliases".path;
+      }
+      {
+        domain = "koma89.tu-darmstadt.de";
+        allowlistPass = config.sops.secrets."allowlistPass/koma".path;
+        virt_aliases = config.sops.secrets."koma.aliases".path;
+      }
+    ];
   };
 
   networking.hostName = "kaalut";
@@ -19,6 +41,25 @@
   system.stateVersion = "24.05";
 
   sops.secrets = {
+    # Virtual alias file
+    "mathebau.aliases" = {
+      sopsFile = ./mathebau.aliases.yaml;
+      owner = "stalwart-mail";
+      group = "stalwart-mail";
+      mode = "0440";
+    };
+    "mathechor.aliases" = {
+      sopsFile = ./mathechor.aliases.yaml;
+      owner = "stalwart-mail";
+      group = "stalwart-mail";
+      mode = "0440";
+    };
+    "koma.aliases" = {
+      sopsFile = ./koma.aliases.yaml;
+      owner = "stalwart-mail";
+      group = "stalwart-mail";
+      mode = "0440";
+    };
     backupKey = {
       sopsFile = ./backupKey.yaml;
       owner = "root";

nixos/machines/kaalut/koma.aliases.yaml

@@ -0,0 +1,48 @@
+koma.aliases: ENC[AES256_GCM,data:r9dJzjUrv9BBr6emtHuIm71OamwTQdxdAbWuh62ZPG/tbvg8YimMvUno1WXn6EXn+0q2Gf+r4UiB6RJLD62D+JU+lEAKg9LKfX+578M4eCIbwRqkHWQYAtT/V3nB8L7/dqcvdatF90+50w==,iv:SL13OY8XUNdVBkZlKBfqwzT5LTtZcykyGIK+nHHOa10=,tag:Yyu2/ZqLotmFD+cMwtXYlA==,type:str]
+sops:
+    kms: []
+    gcp_kms: []
+    azure_kv: []
+    hc_vault: []
+    age:
+        - recipient: age1rasjnr2tlv9y70sj0z0hwpgpxdc974wzg5umtx2pnc6z0p05u3js6r8sln
+          enc: |
+            -----BEGIN AGE ENCRYPTED FILE-----
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBBS283ZTdKVTVLaDRDV1N5
+            SGhJQjJWdXJzc1l5OWtCWVdueTJMdjZpUjJzCmtUZFRYR0JXTW15Z0NyMktEbW5w
+            dkk1TjF0dVQ3MlFhNUFTbU0vMFdySWcKLS0tIDZPQmxSVGYzT2dDM244ek95dk9n
+            SnhtQWJic3B2YTM1ZlE3SHVRSjl1YVkKgUXW7JW3WSM5EusBoxQMsBRGwIqqi7Lo
+            DgWLq/P1rruuqRAS8hl4cht3jz6PlCJgVh2xpaM/kfkFS8ZuhVFw4g==
+            -----END AGE ENCRYPTED FILE-----
+        - recipient: age1epz92k2rkp43hkrg3u0jgkzhnkwx8y43kag7rvfzwl9wcddelvusyetxl7
+          enc: |
+            -----BEGIN AGE ENCRYPTED FILE-----
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBKdmcyM3hSUFdlM25UUndu
+            RUhzdEhsakdEdytBUGRyRTFXRzdYK2RBR0dnCmJqOTlvYkZkeld3eDYvRmRmUU5u
+            aHArR0FkZWRtT0hoNTZpS1JmaTRHencKLS0tIGVVSWN0NWQyQWdrcXdQUnQxUjdu
+            MWFZWVQ3RmZZS3FnRkJPdDRrOTZrWG8KVgFqfeBLw5gTBKugfnC4a5OLwOhosSgy
+            3hXbGMrJiBDwOS+70H3L+IwiNSoJ6mL+ufShCTq8wER2L9GTteI8gg==
+            -----END AGE ENCRYPTED FILE-----
+        - recipient: age1dhzugelagj6vge5jjxwwn0522ngf7fhxn04sxy2tm8557rtme5tstprwnj
+          enc: |
+            -----BEGIN AGE ENCRYPTED FILE-----
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSAzamM5TDVQM0hnZklsbncx
+            SlBMM0NpcnBBai94czV5WE1Md21EeE1kVXpFClpDVTRqYm5rWFhjVjRPQm1IVWxW
+            WTNlZFo4Y3VVNjZhckZ0RFVlQlV0OEEKLS0tIGJOR3k0OUorYTNXL01KQWJBUzVD
+            V0xidWR0SnBDM01hRlkrTlY4eEIrc1EK1Hye/jrQebkEDQ8muJpgHqBLefjnEJPF
+            GxdANetJLuZeeiOUjaUcbP6tecqZpiWN8fFEXrjNL4vnrHvJ+bR1aA==
+            -----END AGE ENCRYPTED FILE-----
+        - recipient: age1ktwclxa640l89le6yecm8v2z6hmwr4lusd6x9gyzamhv57887szqtqp59a
+          enc: |
+            -----BEGIN AGE ENCRYPTED FILE-----
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBqQURCeGJBYytCdlhrWjF5
+            c1ZrbEFENDF5bTNMaE52SE5CS1dVdWJCNlFzClZtK1QxOWY0dEVRRWY4MEtlZ1N1
+            eGlaYXVLMUJiUi9FckdNcllBRCt4cmMKLS0tIEZuOTZQTm9vWHQ4Y3Z6RVloT0VL
+            OW5ZQWIvU2x1OEN6OW84K0dqRmhGNUUKOA3ugnG/ZD7m1DKrFjpZ8opPnjPtLaQx
+            t8qgGuQIoX6KeUb+YybRAOAPPzl51/m9GSUB43Eanm/tVJpdaew7/g==
+            -----END AGE ENCRYPTED FILE-----
+    lastmodified: "2025-02-25T17:41:29Z"
+    mac: ENC[AES256_GCM,data:lZ9AXtJzVuc8Jg9L0aGhS18cs8pTjOG/xNP2tG25/7/PEdEV1SNwbxubGQOFAHrNbiDbmJMKJq96mhV8e3tHszlrzQnU1uyu9MrWiAYwV3CjmwSqC4J9ezSm/AY9e9+OWKn6sb4RVsz9A7aDGUhhoZMycnPNRKlpTuzdTIJK98o=,iv:LxSsZoHkJ2HFXBLWkw+SUb/LYW2ciE1DtzpoV4YLOwQ=,tag:QeYmreRGZk4PqlLWJLLD8g==,type:str]
+    pgp: []
+    unencrypted_suffix: _unencrypted
+    version: 3.9.4

nixos/machines/kaalut/mathechor.aliases.yaml

@@ -0,0 +1,48 @@
+mathechor.aliases: ENC[AES256_GCM,data:VKEGY6KVtgKApnV7N2e2cqy9erDWQ2fb88Gwcpp5th/t0VGp16KGDtGiuQXhY80j6dDIcQMd9bLHzqAzc4+i/WhmEPhiXUkGiEKuarMfvqNl1LBlXFCoIrUXMMSIqab9q+fE3ignVQapE/YZt9aniyvg1prcmBcwIy9rDoHkiTY006ux5CM+vX0F60ADX8Nf6Qmn/JncPxXgq2jYsBxjXPj7BwJaair/+nxrbVf0,iv:Elj1NDeR1fdIIjIbjvkV3BmcVAKjwdMfknuNxMXJsa4=,tag:AkXWQ8sTMLsd7a+MfRcF/w==,type:str]
+sops:
+    kms: []
+    gcp_kms: []
+    azure_kv: []
+    hc_vault: []
+    age:
+        - recipient: age1rasjnr2tlv9y70sj0z0hwpgpxdc974wzg5umtx2pnc6z0p05u3js6r8sln
+          enc: |
+            -----BEGIN AGE ENCRYPTED FILE-----
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBjMlRsWnkrREVaQitsWHMy
+            WHZFVG1qN25QbWFHcUxNS1Z0SFRDd1oxeG5RCi8wNUhkeWh2VjI4ZGowM1ExaExh
+            SE1yVGFTUHZadUdDL3pxaGdKTHQ0VTgKLS0tIHVNM2xlOFNNS3dFalJqZUtPODRn
+            b2NOTHpXSUVyaFRJNG5ONCt0TTVjOEkKYld7KN995QxdrGBVRYgCxO7kGwsiq+cp
+            iQJTjMdoFygIrTkgE5Rj89/GCiVe0+yAWJuQF7PEnC3cyq0M1g+fzw==
+            -----END AGE ENCRYPTED FILE-----
+        - recipient: age1epz92k2rkp43hkrg3u0jgkzhnkwx8y43kag7rvfzwl9wcddelvusyetxl7
+          enc: |
+            -----BEGIN AGE ENCRYPTED FILE-----
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBPRFJCeXhwQVFSWmgzNHBu
+            SHlTTGtiRkI5bmhKa1B0QTZMY3FERmlUd0FBCk1vOUpydEFZUExpR2hpWm9mRHpE
+            dk9MQ042K0FpSVJ3dUlQcktGT2k1VjAKLS0tIHpGRmwzNE01YkV1TW94RkNmMjN4
+            YnNXZUlta3NMVW9Cc3V2T0t4R01RSlkKNTW3gnF49BuPwF3jwciOYThJe+gJa0a6
+            WKYt+aJuHi0a4y5rS/wfttij+hS5vYVNOrgfJ5bGinkNuAygA2hMOg==
+            -----END AGE ENCRYPTED FILE-----
+        - recipient: age1dhzugelagj6vge5jjxwwn0522ngf7fhxn04sxy2tm8557rtme5tstprwnj
+          enc: |
+            -----BEGIN AGE ENCRYPTED FILE-----
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSB6MjZOR1dwb3RjZnlNNW4v
+            SzJnT1BRVktWNDI5S2Z2NnhQQzdNeS9ralI0CnN0SU9ESEV3ZCtRQmpZK3VZOGYx
+            Y3FVUy9zY3RZcGxyVmttVzFJL1haYWsKLS0tIENGRW1KZkpUdldOZWgzSXVoenpX
+            dTVpNUpWallSTzJ3cEZJTXk3c2t1czgKzJCwhMspzAsjzwSRdSPUoseEAsKp8HFy
+            cL9if92ar68HMHTdoy0Zvy+5AbxKUxgXZ2t8cDgkL8bNG5Ri2xYaUA==
+            -----END AGE ENCRYPTED FILE-----
+        - recipient: age1ktwclxa640l89le6yecm8v2z6hmwr4lusd6x9gyzamhv57887szqtqp59a
+          enc: |
+            -----BEGIN AGE ENCRYPTED FILE-----
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBtNm5xUGkrK1dYd2ZtamFW
+            NXpNMEtvNTl3U3MzeVNSbVJOdGdlWGsxRHlZCllQVmNtYzBJNDc2Y0dmUlNsbTF5
+            RHB4QWZ1VGNFVkx1Q0hNK3FDTTRrUlkKLS0tIG9hbldDeHk0YmVZV2IwMXNpYStU
+            Q29uVHBCb2pTeWVJVmVXbWpycnFneWMKnDmu5917dddV8vjO0L8OP3wXMjDi46Ro
+            b9eOY8l74jm4sTxyKNvnkEjD6iHn1t7f8J7HAbWrpZY+J0i77nrzQw==
+            -----END AGE ENCRYPTED FILE-----
+    lastmodified: "2024-11-23T09:05:51Z"
+    mac: ENC[AES256_GCM,data:Xnulo0681LtgH9SZt9DL3nd9bSDH+TCQDvbKdggVBJ66rxBiKmlbu5MAblAWqxbdZ6EelldaVeX9OaL2rYJoYbTWxzw2iuPieldp3Ah3PsTI2C8W+UD9KVHcB+3AMOmVmJZzFlZvTwyfPfZRNNb0HAijkN97P3fP0r1Iqf3YjiI=,iv:vhu38HM4e+PyyChXvI87LWSGtKQQiXUr4MKrI7kotzk=,tag:eNuQD74kUO+duqEXNbLJBw==,type:str]
+    pgp: []
+    unencrypted_suffix: _unencrypted
+    version: 3.9.1

nixos/modules/mail.nix

@@ -1,4 +1,6 @@
 /*
+* Forwarding mails: Update the Sops-secrets in the machine directory, rebuild on the VM and deploy.
+*   Everything else should happen automatically but new redirects might take up to two hours due HRZ infrastructure.
 * Using the web admin interface: Set your SSH to do portforwarding of some local port to port 80 of the VM and
 *   and use your personal admin account or create one using the fallback admin password.
 * Create users with mail boxes: Go to the admin interface and create them.
@@ -9,6 +11,7 @@
 {
   config,
   lib,
+  pkgs,
   ...
 }: let
   inherit
@@ -26,6 +29,25 @@ in {
       type = str;
       description = "String containing the hashed fallback admin password";
     };
+    domains = mkOption {
+      type = listOf (lib.types.submodule {
+        options = {
+          domain = mkOption {
+            description = "Domain name that we serve. We also push its addresses to HRZ.";
+            type = strMatching "^([a-z0-9]+(-[a-z0-9]+)*\.)+[a-z]{2,}$"; #Regex from https://www.oreilly.com/library/view/regular-expressions-cookbook/9781449327453/ch08s15.html
+          };
+          allowlistPass = mkOption {
+            description = "Password file for the HRZ API that gets a list of mailaddresses that we serve";
+            type = path;
+          };
+          virt_aliases = mkOption {
+            description = "File path to a virtual alias file applicable for this domain";
+            type = path;
+            default = "/dev/null"; # there might not be an alias file and reading an empty one works with our implementation
+          };
+        };
+      });
+    };
   };
 
   config = mkIf cfg.enable {
@@ -127,6 +149,32 @@ in {
             ];
           };
 
+          # Stalwart gets its configuration from two places: A TOML configuration file that we control in this module
+          # and from a database that can be configured from web management interface or via Rest API.
+          # We here define what comes from the TOML-file and especially add "sieve.trusted.scripts.*" to the default ones
+          # because only TOML-based keys may use macros to load files from disk.
+          # We want this to be able to load our sieve-script for mail forwarding.
+          config.local-keys =
+            [
+              "store.*"
+              "directory.*"
+              "tracer.*"
+              "server.*"
+              "!server.blocked-ip.*"
+              "authentication.fallback-admin.*"
+              "cluster.node-id"
+              "storage.data"
+              "storage.blob"
+              "storage.lookup"
+              "storage.fts"
+              "storage.directory"
+              "lookup.default.hostname"
+              "certificate.*"
+            ] # the default ones
+            ++ ["sieve.trusted.scripts.*"]; #for macros to be able to include our redirection script
+          sieve.trusted.scripts.redirects.contents = "%{file:/tmp/virt_aliases}%"; # generated redirect script
+          session.data.script = "'redirects'";
+
           authentication.fallback-admin = {
             user = "admin";
             # see passwd on azathoth for plaintext or machine secret in encoded format for HTTP Basic AUTH
@@ -149,6 +197,42 @@ in {
       files = ["/root/.ssh/known_hosts"]; # for the backup server bragi
     };
 
+    systemd = {
+      services = {
+        "stalwart-mail" = {
+          restartTriggers = lib.attrsets.mapAttrsToList (_: aliaslist: aliaslist.sopsFile) config.sops.secrets; # restart if secrets, especially alias files, have changed.
+          serviceConfig.PrivateTmp = lib.mkForce false; # enable access to generated Sieve script
+        };
+        "virt-aliases-generator" = {
+          description = "Virtual Aliases Generator: Generate a sieve script from the virtual alias file";
+          script = lib.strings.concatStringsSep "" (["${pkgs.alias-to-sieve}/bin/alias_to_sieve "] ++ map (x: "${x.virt_aliases} ${x.domain} ") cfg.domains ++ ["> /tmp/virt_aliases"]);
+          wantedBy = ["stalwart-mail.service"]; # Rerun on stalwart restart because forwardings may have changed.
+          serviceConfig = {
+            Type = "oneshot";
+            User = "stalwart-mail";
+            NoNewPrivileges = true;
+            # See https://www.man7.org/linux/man-pages/man5/systemd.exec.5.html
+            PrivateTmp = false;
+            ProtectHome = true;
+            ReadOnlyPaths = "/";
+            ReadWritePaths = "/tmp";
+            InaccessiblePaths = "-/lost+found";
+            PrivateDevices = true;
+            PrivateUsers = true;
+            ProtectHostname = true;
+            ProtectClock = true;
+            ProtectKernelTunables = true;
+            ProtectKernelModules = true;
+            ProtectKernelLogs = true;
+            ProtectControlGroups = true;
+            LockPersonality = true;
+            MemoryDenyWriteExecute = true;
+            RestrictRealtime = true;
+            RestrictSUIDSGID = true;
+          };
+        };
+      };
+    };
     # Backups
     services.borgbackup.jobs.mail = {
       paths = [