{ config, lib, pkgs, ... }: with lib; let cfg = config.security.duosec; boolToStr = b: if b then "yes" else "no"; configFilePam = '' [duo] ikey=${cfg.ikey} skey=${cfg.skey} host=${cfg.host} ${optionalString (cfg.groups != "") ("groups="+cfg.groups)} failmode=${cfg.failmode} pushinfo=${boolToStr cfg.pushinfo} autopush=${boolToStr cfg.autopush} prompts=${toString cfg.prompts} fallback_local_ip=${boolToStr cfg.fallbackLocalIP} ''; configFileLogin = configFilePam + '' motd=${boolToStr cfg.motd} accept_env_factor=${boolToStr cfg.acceptEnvFactor} ''; loginCfgFile = optionalAttrs cfg.ssh.enable { "duo/login_duo.conf" = { source = pkgs.writeText "login_duo.conf" configFileLogin; mode = "0600"; user = "sshd"; }; }; pamCfgFile = optional cfg.pam.enable { "duo/pam_duo.conf" = { source = pkgs.writeText "pam_duo.conf" configFilePam; mode = "0600"; user = "sshd"; }; }; in { imports = [ (mkRenamedOptionModule [ "security" "duosec" "group" ] [ "security" "duosec" "groups" ]) ]; options = { security.duosec = { ssh.enable = mkOption { type = types.bool; default = false; description = "If enabled, protect SSH logins with Duo Security."; }; pam.enable = mkOption { type = types.bool; default = false; description = "If enabled, protect logins with Duo Security using PAM support."; }; ikey = mkOption { type = types.str; description = "Integration key."; }; skey = mkOption { type = types.str; description = "Secret key."; }; host = mkOption { type = types.str; description = "Duo API hostname."; }; groups = mkOption { type = types.str; default = ""; example = "users,!wheel,!*admin guests"; description = '' If specified, Duo authentication is required only for users whose primary group or supplementary group list matches one of the space-separated pattern lists. Refer to <link xlink:href="https://duo.com/docs/duounix"/> for details. ''; }; failmode = mkOption { type = types.enum [ "safe" "secure" ]; default = "safe"; description = '' On service or configuration errors that prevent Duo authentication, fail "safe" (allow access) or "secure" (deny access). The default is "safe". ''; }; pushinfo = mkOption { type = types.bool; default = false; description = '' Include information such as the command to be executed in the Duo Push message. ''; }; autopush = mkOption { type = types.bool; default = false; description = '' If <literal>true</literal>, Duo Unix will automatically send a push login request to the user’s phone, falling back on a phone call if push is unavailable. If <literal>false</literal>, the user will be prompted to choose an authentication method. When configured with <literal>autopush = yes</literal>, we recommend setting <literal>prompts = 1</literal>. ''; }; motd = mkOption { type = types.bool; default = false; description = '' Print the contents of <literal>/etc/motd</literal> to screen after a successful login. ''; }; prompts = mkOption { type = types.enum [ 1 2 3 ]; default = 3; description = '' If a user fails to authenticate with a second factor, Duo Unix will prompt the user to authenticate again. This option sets the maximum number of prompts that Duo Unix will display before denying access. Must be 1, 2, or 3. Default is 3. For example, when <literal>prompts = 1</literal>, the user will have to successfully authenticate on the first prompt, whereas if <literal>prompts = 2</literal>, if the user enters incorrect information at the initial prompt, he/she will be prompted to authenticate again. When configured with <literal>autopush = true</literal>, we recommend setting <literal>prompts = 1</literal>. ''; }; acceptEnvFactor = mkOption { type = types.bool; default = false; description = '' Look for factor selection or passcode in the <literal>$DUO_PASSCODE</literal> environment variable before prompting the user for input. When $DUO_PASSCODE is non-empty, it will override autopush. The SSH client will need SendEnv DUO_PASSCODE in its configuration, and the SSH server will similarly need AcceptEnv DUO_PASSCODE. ''; }; fallbackLocalIP = mkOption { type = types.bool; default = false; description = '' Duo Unix reports the IP address of the authorizing user, for the purposes of authorization and whitelisting. If Duo Unix cannot detect the IP address of the client, setting <literal>fallbackLocalIP = yes</literal> will cause Duo Unix to send the IP address of the server it is running on. If you are using IP whitelisting, enabling this option could cause unauthorized logins if the local IP is listed in the whitelist. ''; }; allowTcpForwarding = mkOption { type = types.bool; default = false; description = '' By default, when SSH forwarding, enabling Duo Security will disable TCP forwarding. By enabling this, you potentially undermine some of the SSH based login security. Note this is not needed if you use PAM. ''; }; }; }; config = mkIf (cfg.ssh.enable || cfg.pam.enable) { environment.systemPackages = [ pkgs.duo-unix ]; security.wrappers.login_duo.source = "${pkgs.duo-unix.out}/bin/login_duo"; environment.etc = loginCfgFile // pamCfgFile; /* If PAM *and* SSH are enabled, then don't do anything special. If PAM isn't used, set the default SSH-only options. */ services.openssh.extraConfig = mkIf (cfg.ssh.enable || cfg.pam.enable) ( if cfg.pam.enable then "UseDNS no" else '' # Duo Security configuration ForceCommand ${config.security.wrapperDir}/login_duo PermitTunnel no ${optionalString (!cfg.allowTcpForwarding) '' AllowTcpForwarding no ''} ''); }; }