nixos-config/lib/fudo/kdc.nix

328 lines
9.9 KiB
Nix

{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.fudo.auth.kdc;
database-file = "${cfg.state-directory}/principals.db";
iprop-log = "${cfg.state-directory}/iprop.log";
acl-file = generate-acl-file cfg.acl;
kdc-conf =
generate-kdc-conf cfg.realm database-file cfg.master-key-file acl-file;
get-domain-hosts = domain:
attrNames
(filterAttrs (host: hostOpts: hostOpts.domain == domain) config.fudo.hosts);
get-host-principals = realm: hostname:
let host = config.fudo.hosts.${hostname};
in map (service: "${service}/${hostname}.${toLower realm}@${realm}")
host.kerberos-services;
add-principal-str = kdc-conf: principal:
"${pkgs.heimdalFull}/bin/kadmin -l -c ${kdc-conf} -- add --random-key --use-defaults ${principal}";
add-hosts-principals = realm: kdc-conf:
concatStringsSep "\n" (map (add-principal-str kdc-conf)
(concatMap (get-host-principals realm)
(get-domain-hosts (toLower realm))));
initialize-db =
realm: user: group: kdc-conf: key-file: db-name: max-lifetime: max-renewal: primary-keytab: kadmin-keytab: kpasswd-keytab: local-hostname:
pkgs.writeShellScript "initialize-kdc-db.sh" ''
if [ ! -e ${key-file} ]; then
${pkgs.heimdalFull}/bin/kstash --key-file=${key-file} --random-key
${pkgs.heimdalFull}/bin/kadmin -l -c ${kdc-conf} -- init --realm-max-ticket-life="${max-lifetime}" --realm-max-renewable-life="${max-renewal}" ${realm}
${add-hosts-principals realm kdc-conf}
${pkgs.heimdalFull}/bin/kadmin -l -c ${kdc-conf} -- ext_keytab --keytab=${primary-keytab} */${local-hostname}@${realm}
${pkgs.heimdalFull}/bin/kadmin -l -c ${kdc-conf} -- ext_keytab --keytab=${kadmin-keytab} kadmin/admin@${realm}
${pkgs.heimdalFull}/bin/kadmin -l -c ${kdc-conf} -- ext_keytab --keytab=${kpasswd-keytab} kadmin/changepw@${realm}
${pkgs.heimdalFull}/bin/kadmin -l -c ${kdc-conf} -- ext_keytab --keytab=${kpasswd-keytab} kadmin/changepw@${realm}
#${pkgs.coreutils}/bin/chown ${user}:${group} ${key-file}
#${pkgs.coreutils}/bin/chown ${user}:${group} ${db-name}
#${pkgs.coreutils}/bin/chown ${user}:${group} ${iprop-log}
#${pkgs.coreutils}/bin/chown ${user}:${group} ${primary-keytab}
#${pkgs.coreutils}/bin/chown ${user}:${group} ${kadmin-keytab}
fi
'';
generate-kdc-conf = realm: db-file: key-file: acl-file:
pkgs.writeText "kdc.conf" ''
[kdc]
database = {
dbname = sqlite:${db-file}
realm = ${realm}
mkey_file = ${key-file}
acl_file = ${acl-file}
log_file = ${iprop-log}
}
[realms]
${realm} = {
enable-http = false
}
[logging]
kdc = FILE:/var/kerberos/kerberos.log
default = FILE:/var/kerberos/kerberos.log
'';
aclEntry = { principal, ... }: {
options = with types; {
perms = let
perms = [
"change-password"
"add"
"list"
"delete"
"modify"
"get"
"get-keys"
"all"
];
in mkOption {
type = listOf (enum perms);
description = "List of permissions.";
default = [ ];
};
target = mkOption {
type = nullOr str;
description = "Target principals.";
default = null;
example = "hosts/*@REALM.COM";
};
};
};
perms-to-permstring = perms: concatStringsSep "," perms;
generate-acl-file = acl-entries:
pkgs.writeText "kdc.acl" (concatStringsSep "\n" (mapAttrsToList
(principal: opts:
"${principal} ${perms-to-permstring opts.perms}${
optionalString (opts.target != null) " ${opts.target}"
}") acl-entries));
kadmin-local = kdc-conf: kadmin-keytab:
pkgs.writeShellScriptBin "kadmin.local" ''
${pkgs.heimdalFull}/bin/kadmin -l -c ${kdc-conf} --keytab=${kadmin-keytab}
'';
in {
options.fudo.auth.kdc = with types; {
enable = mkEnableOption "Fudo KDC";
realm = mkOption {
type = str;
description = "The realm for which we are the acting KDC.";
};
acl = mkOption {
type = attrsOf (submodule aclEntry);
description = "Mapping of pricipals to a list of permissions.";
default = { "*/admin" = [ "all" ]; };
example = {
"*/root" = [ "all" ];
"admin-user" = [ "add" "list" "modify" ];
};
};
bind-addresses = mkOption {
type = listOf str;
description = "A list of IP addresses on which to bind.";
default = [ ];
};
user = mkOption {
type = str;
description = "User as which to run Heimdal servers.";
default = "kerberos";
};
group = mkOption {
type = str;
description = "Group as which to run Heimdal servers.";
default = "kerberos";
};
state-directory = mkOption {
type = str;
description = "Path at which to store kerberos database.";
default = "/var/kerberos";
};
master-key-file = mkOption {
type = str;
description = "File containing the master key for the realm.";
default = "/var/kerberos/master.key";
};
primary-keytab = mkOption {
type = str;
description = "Location of keytab for kadmind.";
default = "/var/kerberos/host.keytab";
};
kadmin-keytab = mkOption {
type = str;
description = "Location of keytab for kadmind.";
default = "/var/kerberos/kadmind.keytab";
};
kpasswdd-keytab = mkOption {
type = str;
description = "Location of keytab for kpasswdd.";
default = "/var/kerberos/kpasswdd.keytab";
};
kdc-internal-port = mkOption {
type = port;
description =
"Localhost port on which to listen for KDC traffic. Port 88 will be forwarded";
default = 4088;
};
# k5login-directory = mkOption {
# type = str;
# description =
# "Directory in which k5login files are stored for local users (equivalent to ~/.k5login).";
# default = "/var/kerberos/k5login";
# };
max-ticket-lifetime = mkOption {
type = str;
description = "Maximum lifetime of a single ticket in this realm.";
default = "1d";
};
max-ticket-renewal = mkOption {
type = str;
description = "Maximum time a ticket may be renewed in this realm.";
default = "7d";
};
};
config = mkIf cfg.enable {
users = {
users.${cfg.user} = {
isSystemUser = true;
home = "/var/kerberos";
group = cfg.group;
};
groups.${cfg.group} = { members = [ cfg.user ]; };
};
krb5 = {
libdefaults = {
# Stick to ~/.k5login
# k5login_directory = cfg.k5login-directory;
ticket_lifetime = cfg.max-ticket-lifetime;
renew_lifetime = cfg.max-ticket-renewal;
};
realms = { ${cfg.realm} = { enable-http = false; }; };
extraConfig = ''
default = FILE:/var/kerberos/kerberos.log
'';
};
environment = {
systemPackages =
[ pkgs.heimdalFull (kadmin-local kdc-conf cfg.kadmin-keytab) ];
etc = {
"krb5.keytab" = {
user = "root";
group = "root";
mode = "0400";
source = cfg.primary-keytab;
};
};
};
fudo.system = {
ensure-directories = {
"${cfg.state-directory}" = {
user = cfg.user;
group = cfg.group;
perms = "0740";
};
};
services = {
heimdal-kdc = let
listen-addrs = concatStringsSep " "
(map (addr: "--addresses=${addr}") cfg.bind-addresses);
command =
"${pkgs.heimdalFull}/libexec/heimdal/kdc -c ${kdc-conf} --ports=88 ${listen-addrs}";
in {
wantedBy = [ "multi-user.target" ];
after = [ "network.target" ];
description =
"Heimdal Kerberos Key Distribution Center (ticket server).";
execStart = command;
user = cfg.user;
group = cfg.group;
workingDirectory = cfg.state-directory;
privateNetwork = false;
addressFamilies = [ "AF_INET" "AF_INET6" ];
requiredCapabilities = [ "CAP_NET_BIND_SERVICE" ];
environment = { KRB5_CONFIG = "/etc/krb5.conf"; };
};
heimdal-kdc-init = {
requires = [ "heimdal-kdc.service" ];
wantedBy = [ "multi-user.target" ];
description = "Initialization script for Heimdal KDC.";
type = "oneshot";
execStart = "${initialize-db cfg.realm cfg.user cfg.group kdc-conf
cfg.master-key-file database-file cfg.max-ticket-lifetime
cfg.max-ticket-renewal cfg.primary-keytab cfg.kadmin-keytab
cfg.kpasswdd-keytab
"${config.networking.hostName}.${toLower cfg.realm}"}";
user = cfg.user;
group = cfg.group;
protectSystem = "full";
addressFamilies = [ "AF_INET" "AF_INET6" ];
workingDirectory = cfg.state-directory;
environment = { KRB5_CONFIG = "/etc/krb5.conf"; };
};
};
};
# FIXME: is this even allowed to be a link?
# systemd.tmpfiles.rules = mkIf (cfg.primary-keytab != "/etc/krb5.keytab")
# [ "L /etc/krb5.keytab - - - - ${cfg.primary-keytab}" ];
services.xinetd = {
enable = true;
services = [
{
name = "kerberos-adm";
user = cfg.user;
server = "${pkgs.heimdalFull}/libexec/heimdal/kadmind";
protocol = "tcp";
serverArgs =
"--config-file=${kdc-conf} --keytab=${cfg.kadmin-keytab}";
}
{
name = "kpasswd";
user = cfg.user;
server = "${pkgs.heimdalFull}/libexec/heimdal/kpasswdd";
protocol = "udp";
serverArgs =
"--config-file=${kdc-conf} --keytab=${cfg.kpasswdd-keytab}";
}
];
};
networking.firewall = {
allowedTCPPorts = [ 88 749 ];
allowedUDPPorts = [ 88 464 ];
};
};
}