nixos/chisel-server: add module

nixos/modules/module-list.nix

@@ -774,6 +774,7 @@
   ./services/networking/blockbook-frontend.nix
   ./services/networking/blocky.nix
   ./services/networking/charybdis.nix
+  ./services/networking/chisel-server.nix
   ./services/networking/cjdns.nix
   ./services/networking/cloudflare-dyndns.nix
   ./services/networking/cntlm.nix

nixos/modules/services/networking/chisel-server.nix

@@ -0,0 +1,99 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.services.chisel-server;
+
+in {
+  options = {
+    services.chisel-server = {
+      enable = mkEnableOption (mdDoc "Chisel Tunnel Server");
+      host = mkOption {
+        description = mdDoc "Address to listen on, falls back to 0.0.0.0";
+        type = with types; nullOr str;
+        default = null;
+        example = "[::1]";
+      };
+      port = mkOption {
+        description = mdDoc "Port to listen on, falls back to 8080";
+        type = with types; nullOr int;
+        default = null;
+      };
+      authfile = mkOption {
+        description = mdDoc "Path to auth.json file";
+        type = with types; nullOr path;
+        default = null;
+      };
+      keepalive  = mkOption {
+        description = mdDoc "Keepalive interval, falls back to 25s";
+        type = with types; nullOr str;
+        default = null;
+        example = "5s";
+      };
+      backend = mkOption {
+        description = mdDoc "HTTP server to proxy normal requests to";
+        type = with types; nullOr str;
+        default = null;
+        example = "http://127.0.0.1:8888";
+      };
+      socks5 = mkOption {
+        description = mdDoc "Allow clients access to internal SOCKS5 proxy";
+        type = types.bool;
+        default = false;
+      };
+      reverse = mkOption {
+        description = mdDoc "Allow clients reverse port forwarding";
+        type = types.bool;
+        default = false;
+      };
+    };
+  };
+
+  config = mkIf cfg.enable {
+    systemd.services.chisel-server = {
+      description = "Chisel Tunnel Server";
+      wantedBy = [ "network-online.target" ];
+
+      serviceConfig = {
+        ExecStart = "${pkgs.chisel}/bin/chisel server " + concatStringsSep " " (
+          optional (cfg.host != null) "--host ${cfg.host}"
+          ++ optional (cfg.port != null) "--port ${builtins.toString cfg.port}"
+          ++ optional (cfg.authfile != null) "--authfile ${cfg.authfile}"
+          ++ optional (cfg.keepalive != null) "--keepalive ${cfg.keepalive}"
+          ++ optional (cfg.backend != null) "--backend ${cfg.backend}"
+          ++ optional cfg.socks5 "--socks5"
+          ++ optional cfg.reverse "--reverse"
+        );
+
+        # Security Hardening
+        # Refer to systemd.exec(5) for option descriptions.
+        CapabilityBoundingSet = "";
+
+        # implies RemoveIPC=, PrivateTmp=, NoNewPrivileges=, RestrictSUIDSGID=,
+        # ProtectSystem=strict, ProtectHome=read-only
+        DynamicUser = true;
+        LockPersonality = true;
+        PrivateDevices = true;
+        PrivateUsers = true;
+        ProcSubset = "pid";
+        ProtectClock = true;
+        ProtectControlGroups = true;
+        ProtectHome = true;
+        ProtectHostname = true;
+        ProtectKernelLogs = true;
+        ProtectProc = "invisible";
+        ProtectKernelModules = true;
+        ProtectKernelTunables = true;
+        RestrictAddressFamilies = [ "AF_INET" "AF_INET6" "AF_UNIX" ];
+        RestrictNamespaces = true;
+        RestrictRealtime = true;
+        SystemCallArchitectures = "native";
+        SystemCallFilter = "~@clock @cpu-emulation @debug @mount @obsolete @reboot @swap @privileged @resources";
+        UMask = "0077";
+      };
+    };
+  };
+
+  meta.maintainers = with maintainers; [ clerie ];
+}