nixpkgs/nixos/modules/services/misc/sssd.nix

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{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.services.sssd;
nscd = config.services.nscd;
dataDir = "/var/lib/sssd";
settingsFile = "${dataDir}/sssd.conf";
2022-08-18 09:34:06 +00:00
settingsFileUnsubstituted = pkgs.writeText "${dataDir}/sssd-unsubstituted.conf" cfg.config;
in {
options = {
services.sssd = {
enable = mkEnableOption (lib.mdDoc "the System Security Services Daemon");
config = mkOption {
type = types.lines;
description = lib.mdDoc "Contents of {file}`sssd.conf`.";
default = ''
[sssd]
config_file_version = 2
services = nss, pam
domains = shadowutils
[nss]
[pam]
[domain/shadowutils]
id_provider = proxy
proxy_lib_name = files
auth_provider = proxy
proxy_pam_target = sssd-shadowutils
proxy_fast_alias = True
'';
};
sshAuthorizedKeysIntegration = mkOption {
type = types.bool;
default = false;
description = lib.mdDoc ''
Whether to make sshd look up authorized keys from SSS.
For this to work, the `ssh` SSS service must be enabled in the sssd configuration.
'';
};
kcm = mkOption {
type = types.bool;
default = false;
description = lib.mdDoc ''
Whether to use SSS as a Kerberos Cache Manager (KCM).
Kerberos will be configured to cache credentials in SSS.
'';
};
environmentFile = mkOption {
type = types.nullOr types.path;
default = null;
description = lib.mdDoc ''
Environment file as defined in {manpage}`systemd.exec(5)`.
Secrets may be passed to the service without adding them to the world-readable
Nix store, by specifying placeholder variables as the option value in Nix and
setting these variables accordingly in the environment file.
```
# snippet of sssd-related config
[domain/LDAP]
ldap_default_authtok = $SSSD_LDAP_DEFAULT_AUTHTOK
```
```
# contents of the environment file
SSSD_LDAP_DEFAULT_AUTHTOK=verysecretpassword
```
'';
};
};
};
config = mkMerge [
(mkIf cfg.enable {
# For `sssctl` to work.
environment.etc."sssd/sssd.conf".source = settingsFile;
environment.etc."sssd/conf.d".source = "${dataDir}/conf.d";
systemd.services.sssd = {
description = "System Security Services Daemon";
wantedBy = [ "multi-user.target" ];
before = [ "systemd-user-sessions.service" "nss-user-lookup.target" ];
after = [ "network-online.target" "nscd.service" ];
requires = [ "network-online.target" "nscd.service" ];
wants = [ "nss-user-lookup.target" ];
restartTriggers = [
config.environment.etc."nscd.conf".source
settingsFileUnsubstituted
];
script = ''
export LDB_MODULES_PATH+="''${LDB_MODULES_PATH+:}${pkgs.ldb}/modules/ldb:${pkgs.sssd}/modules/ldb"
mkdir -p /var/lib/sss/{pubconf,db,mc,pipes,gpo_cache,secrets} /var/lib/sss/pipes/private /var/lib/sss/pubconf/krb5.include.d
${pkgs.sssd}/bin/sssd -D -c ${settingsFile}
'';
serviceConfig = {
Type = "forking";
PIDFile = "/run/sssd.pid";
StateDirectory = baseNameOf dataDir;
# We cannot use LoadCredential here because it's not available in ExecStartPre
EnvironmentFile = lib.mkIf (cfg.environmentFile != null) cfg.environmentFile;
};
preStart = ''
mkdir -p "${dataDir}/conf.d"
[ -f ${settingsFile} ] && rm -f ${settingsFile}
old_umask=$(umask)
umask 0177
${pkgs.envsubst}/bin/envsubst \
-o ${settingsFile} \
-i ${settingsFileUnsubstituted}
umask $old_umask
'';
};
system.nssModules = [ pkgs.sssd ];
system.nssDatabases = {
group = [ "sss" ];
passwd = [ "sss" ];
services = [ "sss" ];
shadow = [ "sss" ];
};
services.dbus.packages = [ pkgs.sssd ];
})
(mkIf cfg.kcm {
systemd.services.sssd-kcm = {
description = "SSSD Kerberos Cache Manager";
requires = [ "sssd-kcm.socket" ];
serviceConfig = {
ExecStartPre = "-${pkgs.sssd}/bin/sssd --genconf-section=kcm";
ExecStart = "${pkgs.sssd}/libexec/sssd/sssd_kcm --uid 0 --gid 0";
};
restartTriggers = [
settingsFileUnsubstituted
];
};
systemd.sockets.sssd-kcm = {
description = "SSSD Kerberos Cache Manager responder socket";
wantedBy = [ "sockets.target" ];
# Matches the default in MIT krb5 and Heimdal:
# https://github.com/krb5/krb5/blob/krb5-1.19.3-final/src/include/kcm.h#L43
listenStreams = [ "/var/run/.heim_org.h5l.kcm-socket" ];
};
krb5.libdefaults.default_ccache_name = "KCM:";
})
(mkIf cfg.sshAuthorizedKeysIntegration {
# Ugly: sshd refuses to start if a store path is given because /nix/store is group-writable.
# So indirect by a symlink.
environment.etc."ssh/authorized_keys_command" = {
mode = "0755";
text = ''
#!/bin/sh
exec ${pkgs.sssd}/bin/sss_ssh_authorizedkeys "$@"
'';
};
services.openssh.authorizedKeysCommand = "/etc/ssh/authorized_keys_command";
services.openssh.authorizedKeysCommandUser = "nobody";
})];
meta.maintainers = with maintainers; [ bbigras ];
}