{ config, lib, pkgs, ... }: with lib; let cfg = config.services.nbd; iniFields = with types; attrsOf (oneOf [ bool int float str ]); # The `[generic]` section must come before all the others in the # config file. This means we can't just dump an attrset to INI # because that sorts the sections by name. Instead, we serialize it # on its own first. genericSection = { generic = (cfg.server.extraOptions // { user = "root"; group = "root"; port = cfg.server.listenPort; } // (optionalAttrs (cfg.server.listenAddress != null) { listenaddr = cfg.server.listenAddress; })); }; exportSections = mapAttrs (_: { path, allowAddresses, extraOptions }: extraOptions // { exportname = path; } // (optionalAttrs (allowAddresses != null) { authfile = pkgs.writeText "authfile" (concatStringsSep "\n" allowAddresses); })) cfg.server.exports; serverConfig = pkgs.writeText "nbd-server-config" '' ${lib.generators.toINI {} genericSection} ${lib.generators.toINI {} exportSections} ''; splitLists = partition (path: hasPrefix "/dev/" path) (mapAttrsToList (_: { path, ... }: path) cfg.server.exports); allowedDevices = splitLists.right; boundPaths = splitLists.wrong; in { options = { services.nbd = { server = { enable = mkEnableOption "the Network Block Device (nbd) server"; listenPort = mkOption { type = types.port; default = 10809; description = "Port to listen on. The port is NOT automatically opened in the firewall."; }; extraOptions = mkOption { type = iniFields; default = { allowlist = false; }; description = '' Extra options for the server. See nbd-server 5. ''; }; exports = mkOption { description = "Files or block devices to make available over the network."; default = { }; type = with types; attrsOf (submodule { options = { path = mkOption { type = str; description = "File or block device to export."; example = "/dev/sdb1"; }; allowAddresses = mkOption { type = nullOr (listOf str); default = null; example = [ "10.10.0.0/24" "127.0.0.1" ]; description = "IPs and subnets that are authorized to connect for this device. If not specified, the server will allow all connections."; }; extraOptions = mkOption { type = iniFields; default = { flush = true; fua = true; }; description = '' Extra options for this export. See nbd-server 5. ''; }; }; }); }; listenAddress = mkOption { type = with types; nullOr str; description = "Address to listen on. If not specified, the server will listen on all interfaces."; default = null; example = "10.10.0.1"; }; }; }; }; config = mkIf cfg.server.enable { assertions = [ { assertion = !(cfg.server.exports ? "generic"); message = "services.nbd.server exports must not be named 'generic'"; } ]; boot.kernelModules = [ "nbd" ]; systemd.services.nbd-server = { after = [ "network-online.target" ]; before = [ "multi-user.target" ]; wantedBy = [ "multi-user.target" ]; serviceConfig = { ExecStart = "${pkgs.nbd}/bin/nbd-server -C ${serverConfig}"; Type = "forking"; DeviceAllow = map (path: "${path} rw") allowedDevices; BindPaths = boundPaths; CapabilityBoundingSet = ""; DevicePolicy = "closed"; LockPersonality = true; MemoryDenyWriteExecute = true; NoNewPrivileges = true; PrivateDevices = false; PrivateMounts = true; PrivateTmp = true; PrivateUsers = true; ProcSubset = "pid"; ProtectClock = true; ProtectControlGroups = true; ProtectHome = true; ProtectHostname = true; ProtectKernelLogs = true; ProtectKernelModules = true; ProtectKernelTunables = true; ProtectProc = "noaccess"; ProtectSystem = "strict"; RestrictAddressFamilies = "AF_INET AF_INET6"; RestrictNamespaces = true; RestrictRealtime = true; RestrictSUIDSGID = true; UMask = "0077"; }; }; }; }