From 0c0b1fcf47bc7298bc5c2a83b1a58f719d4f11c0 Mon Sep 17 00:00:00 2001 From: Rickard Nilsson Date: Fri, 17 May 2013 17:08:32 +0200 Subject: [PATCH] Generate /etc/passwd and /etc/group at build time This is a rather large commit that switches user/group creation from using useradd/groupadd on activation to just generating the contents of /etc/passwd and /etc/group, and then on activation merging the generated files with the files that exist in the system. This makes the user activation process much cleaner, in my opinion. The users.extraUsers..uid and users.extraGroups..gid must all be properly defined (if .createUser is true, which it is by default). My pull request adds a lot of uids/gids to config.ids to solve this problem for existing nixos services, but there might be configurations that break because this change. However, this will be discovered during the build. Option changes introduced by this commit: * Remove the options .isSystemUser and .isAlias since they don't make sense when generating /etc/passwd statically. * Add .members as a complement to .extraGroups. * Add .passwordFile for setting a user's password from an encrypted (shadow-style) file. * Add users.mutableUsers which is true by default. This means you can keep managing your users as previously, by using useradd/groupadd manually. This is accomplished by merging the generated passwd/group file with the existing files in /etc on system activation. The merging of the files is simplistic. It just looks at the user/group names. If a user/group exists both on the system and in the generated files, the system entry will be kept un-changed and the generated entries will be ignored. The merging itself is performed with the help of vipw/vigr to properly lock the account files during edit. If mutableUsers is set to false, the generated passwd and group files will not be merged with the system files on activation. Instead they will simply replace the system files, and overwrite any changes done on the running system. The same logic holds for user password, if the .password or .passwordFile options are used. If mutableUsers is false, password will simply be replaced on activation. If true, the initial user passwords will be set according to the configuration, but existing passwords will not be touched. I have tested this on a couple of different systems and it seems to work fine so far. If you think this is a good idea, please test it. This way of adding local users has been discussed in issue #103 (and this commit solves that issue). --- nixos/modules/config/users-groups.nix | 426 ++++++++++++++------------ nixos/modules/programs/shadow.nix | 2 + 2 files changed, 235 insertions(+), 193 deletions(-) diff --git a/nixos/modules/config/users-groups.nix b/nixos/modules/config/users-groups.nix index 714de646eb7a55a..5d35f07367cf704 100644 --- a/nixos/modules/config/users-groups.nix +++ b/nixos/modules/config/users-groups.nix @@ -5,54 +5,51 @@ with pkgs.lib; let ids = config.ids; - users = config.users; + cfg = config.users; userOpts = { name, config, ... }: { options = { name = mkOption { - type = types.str; - description = "The name of the user account. If undefined, the name of the attribute set will be used."; + type = with types; uniq string; + description = '' + The name of the user account. If undefined, the name of the attribute + set will be used. + ''; }; description = mkOption { - type = types.str; + type = with types; uniq string; 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. - ''; + description = "A short description of the user account."; }; uid = mkOption { - type = with types; uniq (nullOr int); - default = null; - description = "The account UID. If undefined, NixOS will select a free UID."; + type = with types; uniq int; + description = "The account UID."; }; group = mkOption { - type = types.str; + type = with types; uniq string; default = "nogroup"; description = "The user's primary group."; }; extraGroups = mkOption { - type = types.listOf types.str; + type = types.listOf types.string; default = []; description = "The user's auxiliary groups."; }; home = mkOption { - type = types.str; + type = with types; uniq string; default = "/var/empty"; description = "The user's home directory."; }; shell = mkOption { - type = types.str; + type = with types; uniq string; default = "/run/current-system/sw/sbin/nologin"; description = "The path to the user's shell."; }; @@ -60,55 +57,70 @@ let createHome = mkOption { type = types.bool; default = false; - description = "If true, the home directory will be created automatically."; + description = '' + If true, the home directory will be created automatically. If this + option is true and the home directory already exists but is not + owned by the user, directory owner and group will be changed to + match the user. + ''; }; useDefaultShell = mkOption { type = types.bool; default = false; - description = "If true, the user's shell will be set to users.defaultUserShell."; + description = '' + If true, the user's shell will be set to + cfg.defaultUserShell. + ''; }; password = mkOption { - type = with types; uniq (nullOr str); + type = with types; uniq (nullOr string); default = null; description = '' - The user's password. If undefined, no password is set 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 such as - guest. + The user's password in clear text. If undefined, no password is set + for the user. Warning: do not set confidential information here + because this data would be readable by all. This option should only + be used for public accounts such as guest accounts. + The option password overrides + passwordFile, if both are specified. + If none of the options password or + passwordFile are specified, the user account will + be locked for password logins. This is the default behavior except + for the root account, which has an empty password by default. If you + want to lock the root account for password logins, set + users.extraUsers.root.password to + null. ''; }; - isSystemUser = mkOption { - type = types.bool; - default = true; - description = "Indicates if the user is a system user or not."; + passwordFile = mkOption { + type = with types; uniq (nullOr string); + default = null; + description = '' + The 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. + See the password for more details on how passwords + are assigned. + ''; }; createUser = mkOption { type = types.bool; default = true; - description = '' + description = " Indicates if the user should be created automatically as a local user. Set this to false if the user for instance is an LDAP user. NixOS will - then not modify any of the basic properties for the user account. - ''; - }; - - isAlias = mkOption { - type = types.bool; - default = false; - description = "If true, the UID of this user is not required to be unique and can thus alias another user."; + then not add the user to the local passwd file. + "; }; - }; config = { name = mkDefault name; - uid = mkDefault (attrByPath [name] null ids.uids); - shell = mkIf config.useDefaultShell (mkDefault users.defaultUserShell); + shell = mkIf config.useDefaultShell (mkDefault cfg.defaultUserShell); }; }; @@ -118,33 +130,108 @@ let options = { name = mkOption { - type = types.str; - description = "The name of the group. If undefined, the name of the attribute set will be used."; + type = with types; uniq string; + description = '' + The name of the group. If undefined, the name of the attribute + set will be used. + ''; }; gid = mkOption { - type = with types; uniq (nullOr int); - default = null; - description = "The GID of the group. If undefined, NixOS will select a free GID."; + type = with types; uniq int; + description = "The GID of the group."; + }; + + members = mkOption { + type = with types; listOf string; + default = []; + description = '' + ''; }; }; config = { name = mkDefault name; - gid = mkDefault (attrByPath [name] null ids.gids); }; }; - # Note: the 'X' in front of the password is to distinguish between - # having an empty password, and not having a password. - serializedUser = u: "${u.name}\n${u.description}\n${if u.uid != null then toString u.uid else ""}\n${u.group}\n${toString (concatStringsSep "," u.extraGroups)}\n${u.home}\n${u.shell}\n${toString u.createHome}\n${if u.password != null then "X" + u.password else ""}\n${toString u.isSystemUser}\n${toString u.createUser}\n${toString u.isAlias}\n"; - - usersFile = pkgs.writeText "users" ( + getGroup = gname: + let + groups = mapAttrsToList (n: g: g) ( + filterAttrs (n: g: g.name == gname) cfg.extraGroups + ); + in + if length groups == 1 then head groups + else if groups == [] then throw "Group ${gname} not defined" + else throw "Group ${gname} has multiple definitions"; + + getUser = uname: let - p = partition (u: u.isAlias) (attrValues config.users.extraUsers); - in concatStrings (map serializedUser p.wrong ++ map serializedUser p.right)); + users = mapAttrsToList (n: u: u) ( + filterAttrs (n: u: u.name == uname) cfg.extraUsers + ); + in + if length users == 1 then head users + else if users == [] then throw "User ${uname} not defined" + else throw "User ${uname} has multiple definitions"; + + mkGroupEntry = gname: + let + g = getGroup gname; + users = mapAttrsToList (n: u: u.name) ( + filterAttrs (n: u: elem g.name u.extraGroups) cfg.extraUsers + ); + in concatStringsSep ":" [ + g.name "x" (toString g.gid) + (concatStringsSep "," (users ++ (filter (u: !(elem u users)) g.members))) + ]; + + mkPasswdEntry = uname: let u = getUser uname; in + concatStringsSep ":" [ + u.name "x" (toString u.uid) + (toString (getGroup u.group).gid) + u.description u.home u.shell + ]; + + sortOn = a: sort (as1: as2: lessThan (getAttr a as1) (getAttr a as2)); + + groupFile = pkgs.writeText "group" ( + concatStringsSep "\n" (map (g: mkGroupEntry g.name) ( + sortOn "gid" (attrValues cfg.extraGroups) + )) + ); + + passwdFile = pkgs.writeText "passwd" ( + concatStringsSep "\n" (map (u: mkPasswdEntry u.name) ( + sortOn "uid" (filter (u: u.createUser) (attrValues cfg.extraUsers)) + )) + ); + + # If mutableUsers is true, this script adds all users/groups defined in + # users.extra{Users,Groups} to /etc/{passwd,group} iff there isn't any + # existing user/group with the same name in those files. + # If mutableUsers is false, the /etc/{passwd,group} files will simply be + # replaced with the users/groups defined in the NixOS configuration. + # The merging procedure could certainly be improved, and instead of just + # keeping the lines as-is from /etc/{passwd,group} they could be combined + # in some way with the generated content from the NixOS configuration. + merger = src: pkgs.writeScript "merger" '' + #!${pkgs.bash}/bin/bash + + PATH=${pkgs.gawk}/bin:${pkgs.gnugrep}/bin:$PATH + + ${if !cfg.mutableUsers + then ''cp ${src} $1.tmp'' + else ''awk -F: '{ print "^"$1":.*" }' $1 | egrep -vf - ${src} | cat $1 - > $1.tmp'' + } + + # set mtime to +1, otherwise change might go unnoticed (vipw/vigr only looks at mtime) + touch -m -t $(date -d @$(($(stat -c %Y $1)+1)) +%Y%m%d%H%M.%S) $1.tmp + + mv -f $1.tmp $1 + ''; in @@ -154,18 +241,41 @@ in options = { + users.mutableUsers = mkOption { + type = types.bool; + default = true; + description = '' + If 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.extraUsers and + users.extraGroups options. If + mutableUsers is false, the contents of the user and + group files will simply be replaced on system activation. This also + holds for the user passwords; if this option is false, all changed + passwords will be reset according to the + users.extraUsers configuration on activation. If + this option is true, the initial password for a user will be set + according to users.extraUsers, but existing passwords + will not be changed. + ''; + }; + users.extraUsers = mkOption { default = {}; type = types.loaOf types.optionSet; example = { alice = { uid = 1234; - description = "Alice Q. User"; + description = "Alice"; home = "/home/alice"; createHome = true; group = "users"; extraGroups = ["wheel"]; shell = "/bin/sh"; + password = "foobar"; }; }; description = '' @@ -188,20 +298,6 @@ in options = [ groupOpts ]; }; - security.initialRootPassword = mkOption { - type = types.str; - default = ""; - example = "!"; - description = '' - The (hashed) password for the root account set on initial - installation. The empty string denotes that root can login - locally without a password (but not via remote services such - as SSH, or indirectly via su or - sudo). The string ! - prevents root from logging in using a password. - ''; - }; - }; @@ -211,144 +307,88 @@ in users.extraUsers = { root = { + uid = ids.uids.root; description = "System administrator"; home = "/root"; - shell = config.users.defaultUserShell; + shell = cfg.defaultUserShell; group = "root"; + password = mkDefault ""; }; nobody = { + uid = ids.uids.nobody; description = "Unprivileged account (don't use!)"; + group = "nogroup"; }; }; users.extraGroups = { - root = { }; - wheel = { }; - disk = { }; - kmem = { }; - tty = { }; - floppy = { }; - uucp = { }; - lp = { }; - cdrom = { }; - tape = { }; - audio = { }; - video = { }; - dialout = { }; - nogroup = { }; - users = { }; - nixbld = { }; - utmp = { }; - adm = { }; # expected by journald + 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; }; - system.activationScripts.rootPasswd = stringAfter [ "etc" ] - '' - # If there is no password file yet, create a root account with an - # empty password. - if ! test -e /etc/passwd; then - rootHome=/root - touch /etc/passwd; chmod 0644 /etc/passwd - touch /etc/group; chmod 0644 /etc/group - touch /etc/shadow; chmod 0600 /etc/shadow - # Can't use useradd, since it complains that it doesn't know us - # (bootstrap problem!). - echo "root:x:0:0:System administrator:$rootHome:${config.users.defaultUserShell}" >> /etc/passwd - echo "root:${config.security.initialRootPassword}:::::::" >> /etc/shadow - fi - ''; - - # Print a reminder for users to set a root password. - environment.interactiveShellInit = - '' - if [ "$UID" = 0 ]; then - read _l < /etc/shadow - if [ "''${_l:0:6}" = root:: ]; then - cat >&2 </dev/null" + else if (isNull u.password && isNull u.passwordFile) + then "passwd -l '${u.name}' &>/dev/null" + else if !(isNull u.password) + then '' + echo "${u.name}:${u.password}" | ${pkgs.shadow}/sbin/chpasswd'' + else '' + echo -n "${u.name}:" | cat - "${u.passwordFile}" | \ + ${pkgs.shadow}/sbin/chpasswd -e + '' + } + fi + ''; + mkhome = n: u: + let + uid = toString u.uid; + gid = toString ((getGroup u.group).gid); + h = u.home; + in '' + test -a "${h}" || mkdir "${h}" || true + test "`stat -c %u "${h}"`" = ${uid} || chown ${uid} "${h}" || true + test "`stat -c %g "${h}"`" = ${gid} || chgrp ${gid} "${h}" || true + ''; + in stringAfter [ "etc" ] '' + touch /etc/group + touch /etc/passwd + VISUAL=${merger groupFile} ${pkgs.shadow}/sbin/vigr &>/dev/null + VISUAL=${merger passwdFile} ${pkgs.shadow}/sbin/vipw &>/dev/null + ${pkgs.shadow}/sbin/grpconv + ${pkgs.shadow}/sbin/pwconv + ${concatStrings (mapAttrsToList mkhome mkhomeUsers)} + ${concatStrings (mapAttrsToList setpw setpwUsers)} ''; - system.activationScripts.groups = stringAfter [ "rootPasswd" "binsh" "etc" "var" ] - '' - echo "updating groups..." - - createGroup() { - name="$1" - gid="$2" - - if ! curEnt=$(getent group "$name"); then - groupadd --system \ - ''${gid:+--gid $gid} \ - "$name" - fi - } - - ${flip concatMapStrings (attrValues config.users.extraGroups) (g: '' - createGroup '${g.name}' '${toString g.gid}' - '')} - ''; + # for backwards compatibility + system.activationScripts.groups = stringAfter [ "users" ] ""; }; diff --git a/nixos/modules/programs/shadow.nix b/nixos/modules/programs/shadow.nix index 9e46ab8b298fbf4..fdc80331a84e25b 100644 --- a/nixos/modules/programs/shadow.nix +++ b/nixos/modules/programs/shadow.nix @@ -94,6 +94,8 @@ in groupmems = { rootOK = true; }; groupdel = { rootOK = true; }; login = { startSession = true; allowNullPassword = true; showMotd = true; updateWtmp = true; }; + chpasswd = { rootOK = true; }; + chgpasswd = { rootOK = true; }; }; security.setuidPrograms = [ "passwd" "chfn" "su" "newgrp" ];