3 files changed, 211 insertions, 0 deletions
diff --git a/nixos/modules/services/system/kerberos/default.nix b/nixos/modules/services/system/kerberos/default.nix
new file mode 100644
index 00000000000..9a1e6739901
--- /dev/null
+++ b/nixos/modules/services/system/kerberos/default.nix
@@ -0,0 +1,75 @@
+{config, lib, ...}:
+
+let
+  inherit (lib) mkOption mkIf types length attrNames;
+  cfg = config.services.kerberos_server;
+  kerberos = config.krb5.kerberos;
+
+  aclEntry = {
+    options = {
+      principal = mkOption {
+        type = types.str;
+        description = "Which principal the rule applies to";
+      };
+      access = mkOption {
+        type = types.either
+          (types.listOf (types.enum ["add" "cpw" "delete" "get" "list" "modify"]))
+          (types.enum ["all"]);
+        default = "all";
+        description = "The changes the principal is allowed to make.";
+      };
+      target = mkOption {
+        type = types.str;
+        default = "*";
+        description = "The principals that 'access' applies to.";
+      };
+    };
+  };
+
+  realm = {
+    options = {
+      acl = mkOption {
+        type = types.listOf (types.submodule aclEntry);
+        default = [
+          { principal = "*/admin"; access = "all"; }
+          { principal = "admin"; access = "all"; }
+        ];
+        description = ''
+          The privileges granted to a user.
+        '';
+      };
+    };
+  };
+in
+
+{
+  imports = [
+    ./mit.nix
+    ./heimdal.nix
+  ];
+
+  ###### interface
+  options = {
+    services.kerberos_server = {
+      enable = lib.mkEnableOption "the kerberos authentification server";
+
+      realms = mkOption {
+        type = types.attrsOf (types.submodule realm);
+        description = ''
+          The realm(s) to serve keys for.
+        '';
+      };
+    };
+  };
+
+
+  ###### implementation
+
+  config = mkIf cfg.enable {
+    environment.systemPackages = [ kerberos ];
+    assertions = [{
+      assertion = length (attrNames cfg.realms) <= 1;
+      message = "Only one realm per server is currently supported.";
+    }];
+  };
+}
diff --git a/nixos/modules/services/system/kerberos/heimdal.nix b/nixos/modules/services/system/kerberos/heimdal.nix
new file mode 100644
index 00000000000..837c59caa56
--- /dev/null
+++ b/nixos/modules/services/system/kerberos/heimdal.nix
@@ -0,0 +1,68 @@
+{ pkgs, config, lib, ... } :
+
+let
+  inherit (lib) mkIf concatStringsSep concatMapStrings toList mapAttrs
+    mapAttrsToList;
+  cfg = config.services.kerberos_server;
+  kerberos = config.krb5.kerberos;
+  stateDir = "/var/heimdal";
+  aclFiles = mapAttrs
+    (name: {acl, ...}: pkgs.writeText "${name}.acl" (concatMapStrings ((
+      {principal, access, target, ...} :
+      "${principal}\t${concatStringsSep "," (toList access)}\t${target}\n"
+    )) acl)) cfg.realms;
+
+  kdcConfigs = mapAttrsToList (name: value: ''
+    database = {
+      dbname = ${stateDir}/heimdal
+      acl_file = ${value}
+    }
+  '') aclFiles;
+  kdcConfFile = pkgs.writeText "kdc.conf" ''
+    [kdc]
+    ${concatStringsSep "\n" kdcConfigs}
+  '';
+in
+
+{
+  # No documentation about correct triggers, so guessing at them.
+
+  config = mkIf (cfg.enable && kerberos == pkgs.heimdal) {
+    systemd.services.kadmind = {
+      description = "Kerberos Administration Daemon";
+      wantedBy = [ "multi-user.target" ];
+      preStart = ''
+        mkdir -m 0755 -p ${stateDir}
+      '';
+      serviceConfig.ExecStart =
+        "${kerberos}/libexec/heimdal/kadmind --config-file=/etc/heimdal-kdc/kdc.conf";
+      restartTriggers = [ kdcConfFile ];
+    };
+
+    systemd.services.kdc = {
+      description = "Key Distribution Center daemon";
+      wantedBy = [ "multi-user.target" ];
+      preStart = ''
+        mkdir -m 0755 -p ${stateDir}
+      '';
+      serviceConfig.ExecStart =
+        "${kerberos}/libexec/heimdal/kdc --config-file=/etc/heimdal-kdc/kdc.conf";
+      restartTriggers = [ kdcConfFile ];
+    };
+
+    systemd.services.kpasswdd = {
+      description = "Kerberos Password Changing daemon";
+      wantedBy = [ "multi-user.target" ];
+      preStart = ''
+        mkdir -m 0755 -p ${stateDir}
+      '';
+      serviceConfig.ExecStart = "${kerberos}/libexec/heimdal/kpasswdd";
+      restartTriggers = [ kdcConfFile ];
+    };
+
+    environment.etc = {
+      # Can be set via the --config-file option to KDC
+      "heimdal-kdc/kdc.conf".source = kdcConfFile;
+    };
+  };
+}
diff --git a/nixos/modules/services/system/kerberos/mit.nix b/nixos/modules/services/system/kerberos/mit.nix
new file mode 100644
index 00000000000..25d7d51e808
--- /dev/null
+++ b/nixos/modules/services/system/kerberos/mit.nix
@@ -0,0 +1,68 @@
+{ pkgs, config, lib, ... } :
+
+let
+  inherit (lib) mkIf concatStrings concatStringsSep concatMapStrings toList
+    mapAttrs mapAttrsToList;
+  cfg = config.services.kerberos_server;
+  kerberos = config.krb5.kerberos;
+  stateDir = "/var/lib/krb5kdc";
+  PIDFile = "/run/kdc.pid";
+  aclMap = {
+    add = "a"; cpw = "c"; delete = "d"; get = "i"; list = "l"; modify = "m";
+    all = "*";
+  };
+  aclFiles = mapAttrs
+    (name: {acl, ...}: (pkgs.writeText "${name}.acl" (concatMapStrings (
+      {principal, access, target, ...} :
+      let access_code = map (a: aclMap.${a}) (toList access); in
+      "${principal} ${concatStrings access_code} ${target}\n"
+    ) acl))) cfg.realms;
+  kdcConfigs = mapAttrsToList (name: value: ''
+    ${name} = {
+      acl_file = ${value}
+    }
+  '') aclFiles;
+  kdcConfFile = pkgs.writeText "kdc.conf" ''
+    [realms]
+    ${concatStringsSep "\n" kdcConfigs}
+  '';
+  env = {
+    # What Debian uses, could possibly link directly to Nix store?
+    KRB5_KDC_PROFILE = "/etc/krb5kdc/kdc.conf";
+  };
+in
+
+{
+  config = mkIf (cfg.enable && kerberos == pkgs.krb5Full) {
+    systemd.services.kadmind = {
+      description = "Kerberos Administration Daemon";
+      wantedBy = [ "multi-user.target" ];
+      preStart = ''
+        mkdir -m 0755 -p ${stateDir}
+      '';
+      serviceConfig.ExecStart = "${kerberos}/bin/kadmind -nofork";
+      restartTriggers = [ kdcConfFile ];
+      environment = env;
+    };
+
+    systemd.services.kdc = {
+      description = "Key Distribution Center daemon";
+      wantedBy = [ "multi-user.target" ];
+      preStart = ''
+        mkdir -m 0755 -p ${stateDir}
+      '';
+      serviceConfig = {
+        Type = "forking";
+        PIDFile = PIDFile;
+        ExecStart = "${kerberos}/bin/krb5kdc -P ${PIDFile}";
+      };
+      restartTriggers = [ kdcConfFile ];
+      environment = env;
+    };
+
+    environment.etc = {
+      "krb5kdc/kdc.conf".source = kdcConfFile;
+    };
+    environment.variables = env;
+  };
+}