{ config, lib, utils, pkgs, ... }: with lib; let ids = config.ids; cfg = config.users; isPasswdCompatible = str: !(hasInfix ":" str || hasInfix "\n" str); passwdEntry = type: lib.types.addCheck type isPasswdCompatible // { name = "passwdEntry ${type.name}"; description = "${type.description}, not containing newlines or colons"; }; # Check whether a password hash will allow login. allowsLogin = hash: hash == "" # login without password || !(lib.elem hash [ null # password login disabled "!" # password login disabled "!!" # a variant of "!" "*" # password unset ]); passwordDescription = '' The options , and controls what password is set for the user. overrides both and . overrides . If none of these three options are set, no password is assigned to the user, and the user will not be able to do password logins. If the option is true, the password defined in one of the three options will only be set when the user is created for the first time. After that, you are free to change the password with the ordinary user management commands. If is false, you cannot change user passwords, they will always be set according to the password options. ''; hashedPasswordDescription = '' To generate a hashed password run mkpasswd -m sha-512. If set to an empty string (""), this user will be able to log in without being asked for a password (but not via remote services such as SSH, or indirectly via su or sudo). This should only be used for e.g. bootable live systems. Note: this is different from setting an empty password, which ca be achieved using . If set to null (default) this user will not be able to log in using a password (i.e. via login command). ''; userOpts = { name, config, ... }: { options = { name = mkOption { type = passwdEntry types.str; apply = x: assert (builtins.stringLength x < 32 || abort "Username '${x}' is longer than 31 characters which is not allowed!"); x; description = '' The name of the user account. If undefined, the name of the attribute set will be used. ''; }; description = mkOption { type = passwdEntry types.str; default = ""; example = "Alice Q. User"; description = '' A short description of the user account, typically the user's full name. This is actually the “GECOS” or “comment” field in /etc/passwd. ''; }; uid = mkOption { type = with types; nullOr int; default = null; description = '' The account UID. If the UID is null, a free UID is picked on activation. ''; }; isSystemUser = mkOption { type = types.bool; default = false; description = '' Indicates if the user is a system user or not. This option only has an effect if is , in which case it determines whether the user's UID is allocated in the range for system users (below 500) or in the range for normal users (starting at 1000). Exactly one of isNormalUser and isSystemUser must be true. ''; }; isNormalUser = mkOption { type = types.bool; default = false; description = '' Indicates whether this is an account for a “real” user. This automatically sets to users, to true, to /home/username, to true, and to false. Exactly one of isNormalUser and isSystemUser must be true. ''; }; group = mkOption { type = types.str; apply = x: assert (builtins.stringLength x < 32 || abort "Group name '${x}' is longer than 31 characters which is not allowed!"); x; default = "nogroup"; description = "The user's primary group."; }; extraGroups = mkOption { type = types.listOf types.str; default = []; description = "The user's auxiliary groups."; }; home = mkOption { type = passwdEntry types.path; default = "/var/empty"; description = "The user's home directory."; }; cryptHomeLuks = mkOption { type = with types; nullOr str; default = null; description = '' Path to encrypted luks device that contains the user's home directory. ''; }; pamMount = mkOption { type = with types; attrsOf str; default = {}; description = '' Attributes for user's entry in pam_mount.conf.xml. Useful attributes might include path, options, fstype, and server. See for more information. ''; }; shell = mkOption { type = types.nullOr (types.either types.shellPackage (passwdEntry types.path)); default = pkgs.shadow; defaultText = "pkgs.shadow"; example = literalExample "pkgs.bashInteractive"; description = '' The path to the user's shell. Can use shell derivations, like pkgs.bashInteractive. Don’t forget to enable your shell in programs if necessary, like programs.zsh.enable = true;. ''; }; subUidRanges = mkOption { type = with types; listOf (submodule subordinateUidRange); default = []; example = [ { startUid = 1000; count = 1; } { startUid = 100001; count = 65534; } ]; description = '' Subordinate user ids that user is allowed to use. They are set into /etc/subuid and are used by newuidmap for user namespaces. ''; }; subGidRanges = mkOption { type = with types; listOf (submodule subordinateGidRange); default = []; example = [ { startGid = 100; count = 1; } { startGid = 1001; count = 999; } ]; description = '' Subordinate group ids that user is allowed to use. They are set into /etc/subgid and are used by newgidmap for user namespaces. ''; }; createHome = mkOption { type = types.bool; default = false; description = '' Whether to create the home directory and ensure ownership as well as permissions to match the user. ''; }; useDefaultShell = mkOption { type = types.bool; default = false; description = '' If true, the user's shell will be set to . ''; }; hashedPassword = mkOption { type = with types; nullOr (passwdEntry str); default = null; description = '' Specifies the hashed password for the user. ${passwordDescription} ${hashedPasswordDescription} ''; }; password = mkOption { type = with types; nullOr str; default = null; description = '' Specifies the (clear text) password for the user. Warning: do not set confidential information here because it is world-readable in the Nix store. This option should only be used for public accounts. ${passwordDescription} ''; }; passwordFile = mkOption { type = with types; nullOr str; default = null; description = '' The full path to a file that contains the user's password. The password file is read on each system activation. The file should contain exactly one line, which should be the password in an encrypted form that is suitable for the chpasswd -e command. ${passwordDescription} ''; }; initialHashedPassword = mkOption { type = with types; nullOr (passwdEntry str); default = null; description = '' Specifies the initial hashed password for the user, i.e. the hashed password assigned if the user does not already exist. If is true, the password can be changed subsequently using the passwd command. Otherwise, it's equivalent to setting the option. ${hashedPasswordDescription} ''; }; initialPassword = mkOption { type = with types; nullOr str; default = null; description = '' Specifies the initial password for the user, i.e. the password assigned if the user does not already exist. If is true, the password can be changed subsequently using the passwd command. Otherwise, it's equivalent to setting the option. The same caveat applies: the password specified here is world-readable in the Nix store, so it should only be used for guest accounts or passwords that will be changed promptly. ''; }; packages = mkOption { type = types.listOf types.package; default = []; example = literalExample "[ pkgs.firefox pkgs.thunderbird ]"; description = '' The set of packages that should be made available to the user. This is in contrast to , which adds packages to all users. ''; }; }; config = mkMerge [ { name = mkDefault name; shell = mkIf config.useDefaultShell (mkDefault cfg.defaultUserShell); } (mkIf config.isNormalUser { group = mkDefault "users"; createHome = mkDefault true; home = mkDefault "/home/${config.name}"; useDefaultShell = mkDefault true; isSystemUser = mkDefault false; }) # If !mutableUsers, setting ‘initialPassword’ is equivalent to # setting ‘password’ (and similarly for hashed passwords). (mkIf (!cfg.mutableUsers && config.initialPassword != null) { password = mkDefault config.initialPassword; }) (mkIf (!cfg.mutableUsers && config.initialHashedPassword != null) { hashedPassword = mkDefault config.initialHashedPassword; }) ]; }; groupOpts = { name, ... }: { options = { name = mkOption { type = passwdEntry types.str; description = '' The name of the group. If undefined, the name of the attribute set will be used. ''; }; gid = mkOption { type = with types; nullOr int; default = null; description = '' The group GID. If the GID is null, a free GID is picked on activation. ''; }; members = mkOption { type = with types; listOf (passwdEntry str); default = []; description = '' The user names of the group members, added to the /etc/group file. ''; }; }; config = { name = mkDefault name; }; }; subordinateUidRange = { options = { startUid = mkOption { type = types.int; description = '' Start of the range of subordinate user ids that user is allowed to use. ''; }; count = mkOption { type = types.int; default = 1; description = "Count of subordinate user ids"; }; }; }; subordinateGidRange = { options = { startGid = mkOption { type = types.int; description = '' Start of the range of subordinate group ids that user is allowed to use. ''; }; count = mkOption { type = types.int; default = 1; description = "Count of subordinate group ids"; }; }; }; idsAreUnique = set: idAttr: !(fold (name: args@{ dup, acc }: let id = builtins.toString (builtins.getAttr idAttr (builtins.getAttr name set)); exists = builtins.hasAttr id acc; newAcc = acc // (builtins.listToAttrs [ { name = id; value = true; } ]); in if dup then args else if exists then builtins.trace "Duplicate ${idAttr} ${id}" { dup = true; acc = null; } else { dup = false; acc = newAcc; } ) { dup = false; acc = {}; } (builtins.attrNames set)).dup; uidsAreUnique = idsAreUnique (filterAttrs (n: u: u.uid != null) cfg.users) "uid"; gidsAreUnique = idsAreUnique (filterAttrs (n: g: g.gid != null) cfg.groups) "gid"; spec = pkgs.writeText "users-groups.json" (builtins.toJSON { inherit (cfg) mutableUsers; users = mapAttrsToList (_: u: { inherit (u) name uid group description home createHome isSystemUser password passwordFile hashedPassword isNormalUser subUidRanges subGidRanges initialPassword initialHashedPassword; shell = utils.toShellPath u.shell; }) cfg.users; groups = mapAttrsToList (n: g: { inherit (g) name gid; members = g.members ++ (mapAttrsToList (n: u: u.name) ( filterAttrs (n: u: elem g.name u.extraGroups) cfg.users )); }) cfg.groups; }); systemShells = let shells = mapAttrsToList (_: u: u.shell) cfg.users; in filter types.shellPackage.check shells; in { imports = [ (mkAliasOptionModule [ "users" "extraUsers" ] [ "users" "users" ]) (mkAliasOptionModule [ "users" "extraGroups" ] [ "users" "groups" ]) (mkChangedOptionModule [ "security" "initialRootPassword" ] [ "users" "users" "root" "initialHashedPassword" ] (cfg: if cfg.security.initialRootPassword == "!" then null else cfg.security.initialRootPassword)) ]; ###### interface options = { users.mutableUsers = mkOption { type = types.bool; default = true; description = '' If set to true, you are free to add new users and groups to the system with the ordinary useradd and groupadd commands. On system activation, the existing contents of the /etc/passwd and /etc/group files will be merged with the contents generated from the users.users and users.groups options. The initial password for a user will be set according to users.users, but existing passwords will not be changed. If set to false, the contents of the user and group files will simply be replaced on system activation. This also holds for the user passwords; all changed passwords will be reset according to the users.users configuration on activation. ''; }; users.enforceIdUniqueness = mkOption { type = types.bool; default = true; description = '' Whether to require that no two users/groups share the same uid/gid. ''; }; users.users = mkOption { default = {}; type = with types; attrsOf (submodule userOpts); example = { alice = { uid = 1234; description = "Alice Q. User"; home = "/home/alice"; createHome = true; group = "users"; extraGroups = ["wheel"]; shell = "/bin/sh"; }; }; description = '' Additional user accounts to be created automatically by the system. This can also be used to set options for root. ''; }; users.groups = mkOption { default = {}; example = { students.gid = 1001; hackers = { }; }; type = with types; attrsOf (submodule groupOpts); description = '' Additional groups to be created automatically by the system. ''; }; }; ###### implementation config = { users.users = { root = { uid = ids.uids.root; description = "System administrator"; home = "/root"; shell = mkDefault cfg.defaultUserShell; group = "root"; }; nobody = { uid = ids.uids.nobody; isSystemUser = true; description = "Unprivileged account (don't use!)"; group = "nogroup"; }; }; users.groups = { root.gid = ids.gids.root; wheel.gid = ids.gids.wheel; disk.gid = ids.gids.disk; kmem.gid = ids.gids.kmem; tty.gid = ids.gids.tty; floppy.gid = ids.gids.floppy; uucp.gid = ids.gids.uucp; lp.gid = ids.gids.lp; cdrom.gid = ids.gids.cdrom; tape.gid = ids.gids.tape; audio.gid = ids.gids.audio; video.gid = ids.gids.video; dialout.gid = ids.gids.dialout; nogroup.gid = ids.gids.nogroup; users.gid = ids.gids.users; nixbld.gid = ids.gids.nixbld; utmp.gid = ids.gids.utmp; adm.gid = ids.gids.adm; input.gid = ids.gids.input; kvm.gid = ids.gids.kvm; render.gid = ids.gids.render; shadow.gid = ids.gids.shadow; }; system.activationScripts.users = stringAfter [ "stdio" ] '' install -m 0700 -d /root install -m 0755 -d /home ${pkgs.perl.withPackages (p: [ p.FileSlurp p.JSON ])}/bin/perl \ -w ${./update-users-groups.pl} ${spec} ''; # for backwards compatibility system.activationScripts.groups = stringAfter [ "users" ] ""; # Install all the user shells environment.systemPackages = systemShells; environment.etc = (mapAttrs' (_: { packages, name, ... }: { name = "profiles/per-user/${name}"; value.source = pkgs.buildEnv { name = "user-environment"; paths = packages; inherit (config.environment) pathsToLink extraOutputsToInstall; inherit (config.system.path) ignoreCollisions postBuild; }; }) (filterAttrs (_: u: u.packages != []) cfg.users)); environment.profiles = [ "$HOME/.nix-profile" "/etc/profiles/per-user/$USER" ]; assertions = [ { assertion = !cfg.enforceIdUniqueness || (uidsAreUnique && gidsAreUnique); message = "UIDs and GIDs must be unique!"; } { # If mutableUsers is false, to prevent users creating a # configuration that locks them out of the system, ensure that # there is at least one "privileged" account that has a # password or an SSH authorized key. Privileged accounts are # root and users in the wheel group. assertion = !cfg.mutableUsers -> any id ((mapAttrsToList (_: cfg: (cfg.name == "root" || cfg.group == "wheel" || elem "wheel" cfg.extraGroups) && (allowsLogin cfg.hashedPassword || cfg.password != null || cfg.passwordFile != null || cfg.openssh.authorizedKeys.keys != [] || cfg.openssh.authorizedKeys.keyFiles != []) ) cfg.users) ++ [ config.security.googleOsLogin.enable ]); message = '' Neither the root account nor any wheel user has a password or SSH authorized key. You must set one to prevent being locked out of your system.''; } ] ++ flatten (flip mapAttrsToList cfg.users (name: user: [ { assertion = (user.hashedPassword != null) -> (builtins.match ".*:.*" user.hashedPassword == null); message = '' The password hash of user "${user.name}" contains a ":" character. This is invalid and would break the login system because the fields of /etc/shadow (file where hashes are stored) are colon-separated. Please check the value of option `users.users."${user.name}".hashedPassword`.''; } { assertion = let xor = a: b: a && !b || b && !a; isEffectivelySystemUser = user.isSystemUser || (user.uid != null && user.uid < 500); in xor isEffectivelySystemUser user.isNormalUser; message = '' Exactly one of users.users.${user.name}.isSystemUser and users.users.${user.name}.isNormalUser must be set. ''; } ] )); warnings = builtins.filter (x: x != null) ( flip mapAttrsToList cfg.users (_: user: # This regex matches a subset of the Modular Crypto Format (MCF)[1] # informal standard. Since this depends largely on the OS or the # specific implementation of crypt(3) we only support the (sane) # schemes implemented by glibc and BSDs. In particular the original # DES hash is excluded since, having no structure, it would validate # common mistakes like typing the plaintext password. # # [1]: https://en.wikipedia.org/wiki/Crypt_(C) let sep = "\\$"; base64 = "[a-zA-Z0-9./]+"; id = "[a-z0-9-]+"; value = "[a-zA-Z0-9/+.-]+"; options = "${id}(=${value})?(,${id}=${value})*"; scheme = "${id}(${sep}${options})?"; content = "${base64}${sep}${base64}"; mcf = "^${sep}${scheme}${sep}${content}$"; in if (allowsLogin user.hashedPassword && user.hashedPassword != "" # login without password && builtins.match mcf user.hashedPassword == null) then '' The password hash of user "${user.name}" may be invalid. You must set a valid hash or the user will be locked out of their account. Please check the value of option `users.users."${user.name}".hashedPassword`.'' else null )); }; }