krebs.tinc: add tincUpExtra

krebs/3modules/tinc.nix

@@ -75,6 +75,7 @@ let
               ${iproute}/sbin/ip -6 addr add ${net.ip6.addr} dev ${netname}
               ${iproute}/sbin/ip -6 route add ${net.ip6.prefix} dev ${netname}
             ''}
+            ${tinc.config.tincUpExtra}
           '';
           description = ''
             tinc-up script to be used. Defaults to setting the
@@ -83,6 +84,11 @@ let
           '';
         };
 
+        tincUpExtra = mkOption {
+          type = types.str;
+          default = "";
+        };
+
         tincPackage = mkOption {
           type = types.package;
           default = pkgs.tinc;