nixos/stunnel: Make free-form

nixos/modules/services/networking/stunnel.nix

@@ -7,80 +7,27 @@ let
   cfg = config.services.stunnel;
   yesNo = val: if val then "yes" else "no";
 
+  verifyRequiredField = type: field: n: c: {
+    assertion = hasAttr field c;
+    message =  "stunnel: \"${n}\" ${type} configuration - Field ${field} is required.";
+  };
+
   verifyChainPathAssert = n: c: {
-    assertion = c.verifyHostname == null || (c.verifyChain || c.verifyPeer);
+    assertion = (c.verifyHostname or null) == null || (c.verifyChain || c.verifyPeer);
     message =  "stunnel: \"${n}\" client configuration - hostname verification " +
       "is not possible without either verifyChain or verifyPeer enabled";
   };
 
-  serverConfig = {
-    options = {
-      accept = mkOption {
-        type = types.either types.str types.int;
-        description = ''
-          On which [host:]port stunnel should listen for incoming TLS connections.
-          Note that unlike other softwares stunnel ipv6 address need no brackets,
-          so to listen on all IPv6 addresses on port 1234 one would use ':::1234'.
-        '';
-      };
-
-      connect = mkOption {
-        type = types.either types.str types.int;
-        description = "Port or IP:Port to which the decrypted connection should be forwarded.";
-      };
-
-      cert = mkOption {
-        type = types.path;
-        description = "File containing both the private and public keys.";
-      };
-    };
-  };
-
-  clientConfig = {
-    options = {
-      accept = mkOption {
-        type = types.str;
-        description = "IP:Port on which connections should be accepted.";
-      };
-
-      connect = mkOption {
-        type = types.str;
-        description = "IP:Port destination to connect to.";
-      };
-
-      verifyChain = mkOption {
-        type = types.bool;
-        default = true;
-        description = "Check if the provided certificate has a valid certificate chain (against CAPath).";
-      };
-
-      verifyPeer = mkOption {
-        type = types.bool;
-        default = false;
-        description = "Check if the provided certificate is contained in CAPath.";
-      };
-
-      CAPath = mkOption {
-        type = types.nullOr types.path;
-        default = null;
-        description = "Path to a directory containing certificates to validate against.";
-      };
-
-      CAFile = mkOption {
-        type = types.nullOr types.path;
-        default = "${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt";
-        defaultText = literalExpression ''"''${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt"'';
-        description = "Path to a file containing certificates to validate against.";
-      };
-
-      verifyHostname = mkOption {
-        type = with types; nullOr str;
-        default = null;
-        description = "If set, stunnel checks if the provided certificate is valid for the given hostname.";
-      };
-    };
-  };
-
+  removeNulls = mapAttrs (_: filterAttrs (_: v: v != null));
+  mkValueString = v:
+    if v == true then "yes"
+    else if v == false then "no"
+    else generators.mkValueStringDefault {} v;
+  generateConfig = c:
+    generators.toINI {
+      mkSectionName = id;
+      mkKeyValue = k: v: "${k} = ${mkValueString v}";
+    } (removeNulls c);
 
 in
 
@@ -130,8 +77,13 @@ in
 
 
       servers = mkOption {
-        description = "Define the server configuations.";
-        type = with types; attrsOf (submodule serverConfig);
+        description = ''
+          Define the server configuations.
+
+          See "SERVICE-LEVEL OPTIONS" in <citerefentry><refentrytitle>stunnel</refentrytitle>
+          <manvolnum>8</manvolnum></citerefentry>.
+        '';
+        type = with types; attrsOf (attrsOf (nullOr (oneOf [bool int str])));
         example = {
           fancyWebserver = {
             accept = 443;
@@ -143,8 +95,33 @@ in
       };
 
       clients = mkOption {
-        description = "Define the client configurations.";
-        type = with types; attrsOf (submodule clientConfig);
+        description = ''
+          Define the client configurations.
+
+          By default, verifyChain and OCSPaia are enabled and a CAFile is provided from pkgs.cacert.
+
+          See "SERVICE-LEVEL OPTIONS" in <citerefentry><refentrytitle>stunnel</refentrytitle>
+          <manvolnum>8</manvolnum></citerefentry>.
+        '';
+        type = with types; attrsOf (attrsOf (nullOr (oneOf [bool int str])));
+
+        apply = let
+          applyDefaults = c:
+            {
+              CAFile = "${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt";
+              OCSPaia = true;
+              verifyChain = true;
+            } // c;
+          setCheckHostFromVerifyHostname = c:
+            # To preserve backward-compatibility with the old NixOS stunnel module
+            # definition, allow "verifyHostname" as an alias for "checkHost".
+            c // {
+              checkHost = c.checkHost or c.verifyHostname or null;
+              verifyHostname = null; # Not a real stunnel configuration setting
+            };
+          forceClient = c: c // { client = true; };
+        in mapAttrs (_: c: forceClient (setCheckHostFromVerifyHostname (applyDefaults c)));
+
         example = {
           foobar = {
             accept = "0.0.0.0:8080";
@@ -169,6 +146,11 @@ in
       })
 
       (mapAttrsToList verifyChainPathAssert cfg.clients)
+      (mapAttrsToList (verifyRequiredField "client" "accept") cfg.clients)
+      (mapAttrsToList (verifyRequiredField "client" "connect") cfg.clients)
+      (mapAttrsToList (verifyRequiredField "server" "accept") cfg.servers)
+      (mapAttrsToList (verifyRequiredField "server" "cert") cfg.servers)
+      (mapAttrsToList (verifyRequiredField "server" "connect") cfg.servers)
     ];
 
     environment.systemPackages = [ pkgs.stunnel ];
@@ -183,36 +165,10 @@ in
       ${ optionalString cfg.enableInsecureSSLv3 "options = -NO_SSLv3" }
 
       ; ----- SERVER CONFIGURATIONS -----
-      ${ lib.concatStringsSep "\n"
-           (lib.mapAttrsToList
-             (n: v: ''
-               [${n}]
-               accept = ${toString v.accept}
-               connect = ${toString v.connect}
-               cert = ${v.cert}
-
-             '')
-           cfg.servers)
-      }
+      ${ generateConfig cfg.servers }
 
       ; ----- CLIENT CONFIGURATIONS -----
-      ${ lib.concatStringsSep "\n"
-           (lib.mapAttrsToList
-             (n: v: ''
-               [${n}]
-               client = yes
-               accept = ${v.accept}
-               connect = ${v.connect}
-               verifyChain = ${yesNo v.verifyChain}
-               verifyPeer = ${yesNo v.verifyPeer}
-               ${optionalString (v.CAPath != null) "CApath = ${v.CAPath}"}
-               ${optionalString (v.CAFile != null) "CAFile = ${v.CAFile}"}
-               ${optionalString (v.verifyHostname != null) "checkHost = ${v.verifyHostname}"}
-               OCSPaia = yes
-
-             '')
-           cfg.clients)
-      }
+      ${ generateConfig cfg.clients }
     '';
 
     systemd.services.stunnel = {

nixos/tests/all-tests.nix

@@ -483,6 +483,7 @@ in
   starship = handleTest ./starship.nix {};
   step-ca = handleTestOn ["x86_64-linux"] ./step-ca.nix {};
   strongswan-swanctl = handleTest ./strongswan-swanctl.nix {};
+  stunnel = handleTest ./stunnel.nix {};
   sudo = handleTest ./sudo.nix {};
   sway = handleTest ./sway.nix {};
   switchTest = handleTest ./switch-test.nix {};

nixos/tests/stunnel.nix

@@ -0,0 +1,174 @@
+{ system ? builtins.currentSystem, config ? { }
+, pkgs ? import ../.. { inherit system config; } }:
+
+with import ../lib/testing-python.nix { inherit system pkgs; };
+with pkgs.lib;
+
+let
+  stunnelCommon = {
+    services.stunnel = {
+      enable = true;
+      user = "stunnel";
+    };
+    users.groups.stunnel = { };
+    users.users.stunnel = {
+      isSystemUser = true;
+      group = "stunnel";
+    };
+  };
+  makeCert = { config, pkgs, ... }: {
+    system.activationScripts.create-test-cert = stringAfter [ "users" ] ''
+      ${pkgs.openssl}/bin/openssl req -batch -x509 -newkey rsa -nodes -out /test-cert.pem -keyout /test-key.pem -subj /CN=${config.networking.hostName}
+      ( umask 077; cat /test-key.pem /test-cert.pem > /test-key-and-cert.pem )
+      chown stunnel /test-key.pem /test-key-and-cert.pem
+    '';
+  };
+  serverCommon = { pkgs, ... }: {
+    networking.firewall.allowedTCPPorts = [ 443 ];
+    services.stunnel.servers.https = {
+      accept = "443";
+      connect = 80;
+      cert = "/test-key-and-cert.pem";
+    };
+    systemd.services.simple-webserver = {
+      wantedBy = [ "multi-user.target" ];
+      script = ''
+        cd /etc/webroot
+        ${pkgs.python3}/bin/python -m http.server 80
+      '';
+    };
+  };
+  copyCert = src: dest: filename: ''
+    from shlex import quote
+    ${src}.wait_for_file("/test-key-and-cert.pem")
+    server_cert = ${src}.succeed("cat /test-cert.pem")
+    ${dest}.succeed("echo %s > ${filename}" % quote(server_cert))
+  '';
+
+in {
+  basicServer = makeTest {
+    name = "basicServer";
+
+    nodes = {
+      client = { };
+      server = {
+        imports = [ makeCert serverCommon stunnelCommon ];
+        environment.etc."webroot/index.html".text = "well met";
+      };
+    };
+
+    testScript = ''
+      start_all()
+
+      ${copyCert "server" "client" "/authorized-server-cert.crt"}
+
+      server.wait_for_unit("simple-webserver")
+      server.wait_for_unit("stunnel")
+
+      client.succeed("curl --fail --cacert /authorized-server-cert.crt https://server/ > out")
+      client.succeed('[[ "$(< out)" == "well met" ]]')
+    '';
+  };
+
+  serverAndClient = makeTest {
+    name = "serverAndClient";
+
+    nodes = {
+      client = {
+        imports = [ stunnelCommon ];
+        services.stunnel.clients = {
+          httpsClient = {
+            accept = "80";
+            connect = "server:443";
+            CAFile = "/authorized-server-cert.crt";
+          };
+          httpsClientWithHostVerify = {
+            accept = "81";
+            connect = "server:443";
+            CAFile = "/authorized-server-cert.crt";
+            verifyHostname = "server";
+          };
+          httpsClientWithHostVerifyFail = {
+            accept = "82";
+            connect = "server:443";
+            CAFile = "/authorized-server-cert.crt";
+            verifyHostname = "wronghostname";
+          };
+        };
+      };
+      server = {
+        imports = [ makeCert serverCommon stunnelCommon ];
+        environment.etc."webroot/index.html".text = "hello there";
+      };
+    };
+
+    testScript = ''
+      start_all()
+
+      ${copyCert "server" "client" "/authorized-server-cert.crt"}
+
+      server.wait_for_unit("simple-webserver")
+      server.wait_for_unit("stunnel")
+
+      # In case stunnel came up before we got the server's cert copied over
+      client.succeed("systemctl reload-or-restart stunnel")
+
+      client.succeed("curl --fail http://localhost/ > out")
+      client.succeed('[[ "$(< out)" == "hello there" ]]')
+
+      client.succeed("curl --fail http://localhost:81/ > out")
+      client.succeed('[[ "$(< out)" == "hello there" ]]')
+
+      client.fail("curl --fail http://localhost:82/ > out")
+      client.succeed('[[ "$(< out)" == "" ]]')
+    '';
+  };
+
+  mutualAuth = makeTest {
+    name = "mutualAuth";
+
+    nodes = rec {
+      client = {
+        imports = [ makeCert stunnelCommon ];
+        services.stunnel.clients.authenticated-https = {
+          accept = "80";
+          connect = "server:443";
+          verifyPeer = true;
+          CAFile = "/authorized-server-cert.crt";
+          cert = "/test-cert.pem";
+          key = "/test-key.pem";
+        };
+      };
+      wrongclient = client;
+      server = {
+        imports = [ makeCert serverCommon stunnelCommon ];
+        services.stunnel.servers.https = {
+          CAFile = "/authorized-client-certs.crt";
+          verifyPeer = true;
+        };
+        environment.etc."webroot/index.html".text = "secret handshake";
+      };
+    };
+
+    testScript = ''
+      start_all()
+
+      ${copyCert "server" "client" "/authorized-server-cert.crt"}
+      ${copyCert "client" "server" "/authorized-client-certs.crt"}
+      ${copyCert "server" "wrongclient" "/authorized-server-cert.crt"}
+
+      # In case stunnel came up before we got the cross-certs in place
+      client.succeed("systemctl reload-or-restart stunnel")
+      server.succeed("systemctl reload-or-restart stunnel")
+      wrongclient.succeed("systemctl reload-or-restart stunnel")
+
+      server.wait_for_unit("simple-webserver")
+      client.fail("curl --fail --insecure https://server/ > out")
+      client.succeed('[[ "$(< out)" == "" ]]')
+      client.succeed("curl --fail http://localhost/ > out")
+      client.succeed('[[ "$(< out)" == "secret handshake" ]]')
+      wrongclient.fail("curl --fail http://localhost/ > out")
+      wrongclient.succeed('[[ "$(< out)" == "" ]]')
+    '';
+  };
+}

pkgs/tools/networking/stunnel/default.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, fetchurl, openssl }:
+{ lib, stdenv, fetchurl, openssl, nixosTests }:
 
 stdenv.mkDerivation rec {
   pname = "stunnel";
@@ -28,6 +28,10 @@ stdenv.mkDerivation rec {
     "localstatedir=\${TMPDIR}"
   ];
 
+  passthru.tests = {
+    stunnel = nixosTests.stunnel;
+  };
+
   meta = {
     description = "Universal tls/ssl wrapper";
     homepage    = "https://www.stunnel.org/";