nixpkgs/nixos/modules/config/users-groups.nix
Shea Levy e058de1642 Add option to enforce uniqueness of uids/gids (on by default)
Signed-off-by: Shea Levy <shea@shealevy.com>
2014-02-07 09:57:28 -05:00

459 lines
15 KiB
Nix

{pkgs, config, ...}:
with pkgs.lib;
let
ids = config.ids;
cfg = config.users;
passwordDescription = ''
The options <literal>hashedPassword</literal>,
<literal>password</literal> and <literal>passwordFile</literal>
controls what password is set for the user.
<literal>hashedPassword</literal> overrides both
<literal>password</literal> and <literal>passwordFile</literal>.
<literal>password</literal> overrides <literal>passwordFile</literal>.
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 <literal>users.mutableUsers</literal> 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
<literal>users.mutableUsers</literal> is false, you cannot change
user passwords, they will always be set according to the password
options.
'';
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.";
};
description = mkOption {
type = 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 <filename>/etc/passwd</filename>.
'';
};
uid = mkOption {
type = with types; uniq int;
description = "The account UID.";
};
group = mkOption {
type = types.str;
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 = types.str;
default = "/var/empty";
description = "The user's home directory.";
};
shell = mkOption {
type = types.str;
default = "/run/current-system/sw/sbin/nologin";
description = "The path to the user's shell.";
};
createHome = mkOption {
type = types.bool;
default = false;
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
<literal>cfg.defaultUserShell</literal>.
'';
};
hashedPassword = mkOption {
type = with types; uniq (nullOr str);
default = null;
description = ''
Specifies the (hashed) password for the user.
${passwordDescription}
'';
};
password = mkOption {
type = with types; uniq (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; 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 <literal>chpasswd -e</literal> command.
${passwordDescription}
'';
};
createUser = mkOption {
type = types.bool;
default = true;
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.
'';
};
};
config = {
name = mkDefault name;
shell = mkIf config.useDefaultShell (mkDefault cfg.defaultUserShell);
};
};
groupOpts = { name, config, ... }: {
options = {
name = mkOption {
type = types.str;
description = "The name of the group. If undefined, the name of the attribute set will be used.";
};
gid = mkOption {
type = with types; uniq int;
description = "The GID of the group.";
};
members = mkOption {
type = with types; listOf string;
default = [];
description = ''
The user names of the group members, added to the
<literal>/etc/group</literal> file.
'';
};
};
config = {
name = mkDefault name;
};
};
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
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
'';
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 cfg.extraUsers "uid";
gidsAreUnique = idsAreUnique cfg.extraGroups "gid";
in
{
###### interface
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 <literal>useradd</literal> and
<literal>groupadd</literal> commands. On system activation, the
existing contents of the <literal>/etc/passwd</literal> and
<literal>/etc/group</literal> files will be merged with the
contents generated from the <literal>users.extraUsers</literal> and
<literal>users.extraGroups</literal> options. If
<literal>mutableUsers</literal> 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
<literal>users.extraUsers</literal> configuration on activation. If
this option is true, the initial password for a user will be set
according to <literal>users.extraUsers</literal>, but existing passwords
will not be changed.
'';
};
users.enforceIdUniqueness = mkOption {
type = types.bool;
default = true;
description = ''
Whether to require that no two users/groups share the same uid/gid.
'';
};
users.extraUsers = mkOption {
default = {};
type = types.loaOf types.optionSet;
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.
'';
options = [ userOpts ];
};
users.extraGroups = mkOption {
default = {};
example =
{ students.gid = 1001;
hackers = { };
};
type = types.loaOf types.optionSet;
description = ''
Additional groups to be created automatically by the system.
'';
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 <command>su</command> or
<command>sudo</command>). The string <literal>!</literal>
prevents root from logging in using a password.
Note, setting this option sets
<literal>users.extraUsers.root.hashedPassword</literal>.
Note, if <literal>users.mutableUsers</literal> is false
you cannot change the root password manually, so in that case
the name of this option is a bit misleading, since it will define
the root password beyond the user initialisation phase.
'';
};
};
###### implementation
config = {
users.extraUsers = {
root = {
uid = ids.uids.root;
description = "System administrator";
home = "/root";
shell = cfg.defaultUserShell;
group = "root";
hashedPassword = config.security.initialRootPassword;
};
nobody = {
uid = ids.uids.nobody;
description = "Unprivileged account (don't use!)";
group = "nogroup";
};
};
users.extraGroups = {
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.users =
let
mkhomeUsers = filterAttrs (n: u: u.createHome) cfg.extraUsers;
setpwUsers = filterAttrs (n: u: u.createUser) cfg.extraUsers;
setpw = n: u: ''
setpw=yes
${optionalString cfg.mutableUsers ''
test "$(getent shadow '${u.name}' | cut -d: -f2)" != "x" && setpw=no
''}
if [ "$setpw" == "yes" ]; then
${if !(isNull u.hashedPassword)
then ''
echo "${u.name}:${u.hashedPassword}" | \
${pkgs.shadow}/sbin/chpasswd -e''
else if u.password == ""
then "passwd -d '${u.name}' &>/dev/null"
else if !(isNull u.password)
then ''
echo "${u.name}:${u.password}" | ${pkgs.shadow}/sbin/chpasswd''
else if !(isNull u.passwordFile)
then ''
echo -n "${u.name}:" | cat - "${u.passwordFile}" | \
${pkgs.shadow}/sbin/chpasswd -e
''
else "passwd -l '${u.name}' &>/dev/null"
}
fi
'';
mkhome = n: u:
let
uid = toString u.uid;
gid = toString ((getGroup u.group).gid);
h = u.home;
in ''
test -a "${h}" || mkdir -p "${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)}
'';
# for backwards compatibility
system.activationScripts.groups = stringAfter [ "users" ] "";
assertions = [ { assertion = !cfg.enforceIdUniqueness || (uidsAreUnique && gidsAreUnique); message = "uids and gids must be unique!"; } ];
};
}