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nixpkgs/nixos/modules/services/networking/yggdrasil.nix
Gemini Lasswell 28f51d7757 nixos/yggdrasil: set directory permissions before writing keys
Remove the opportunity for someone to read the keys in between when
they are written and when the chmod is done.  Addresses .
2021-05-08 09:49:19 +02:00

202 lines
7 KiB
Nix

{ config, lib, pkgs, ... }:
with lib;
let
keysPath = "/var/lib/yggdrasil/keys.json";
cfg = config.services.yggdrasil;
configProvided = cfg.config != { };
configFileProvided = cfg.configFile != null;
in {
options = with types; {
services.yggdrasil = {
enable = mkEnableOption "the yggdrasil system service";
config = mkOption {
type = attrs;
default = {};
example = {
Peers = [
"tcp://aa.bb.cc.dd:eeeee"
"tcp://[aaaa:bbbb:cccc:dddd::eeee]:fffff"
];
Listen = [
"tcp://0.0.0.0:xxxxx"
];
};
description = ''
Configuration for yggdrasil, as a Nix attribute set.
Warning: this is stored in the WORLD-READABLE Nix store!
Therefore, it is not appropriate for private keys. If you
wish to specify the keys, use <option>configFile</option>.
If the <option>persistentKeys</option> is enabled then the
keys that are generated during activation will override
those in <option>config</option> or
<option>configFile</option>.
If no keys are specified then ephemeral keys are generated
and the Yggdrasil interface will have a random IPv6 address
each time the service is started, this is the default.
If both <option>configFile</option> and <option>config</option>
are supplied, they will be combined, with values from
<option>configFile</option> taking precedence.
You can use the command <code>nix-shell -p yggdrasil --run
"yggdrasil -genconf"</code> to generate default
configuration values with documentation.
'';
};
configFile = mkOption {
type = nullOr path;
default = null;
example = "/run/keys/yggdrasil.conf";
description = ''
A file which contains JSON configuration for yggdrasil.
See the <option>config</option> option for more information.
'';
};
group = mkOption {
type = types.str;
default = "root";
example = "wheel";
description = "Group to grant access to the Yggdrasil control socket.";
};
openMulticastPort = mkOption {
type = bool;
default = false;
description = ''
Whether to open the UDP port used for multicast peer
discovery. The NixOS firewall blocks link-local
communication, so in order to make local peering work you
will also need to set <code>LinkLocalTCPPort</code> in your
yggdrasil configuration (<option>config</option> or
<option>configFile</option>) to a port number other than 0,
and then add that port to
<option>networking.firewall.allowedTCPPorts</option>.
'';
};
denyDhcpcdInterfaces = mkOption {
type = listOf str;
default = [];
example = [ "tap*" ];
description = ''
Disable the DHCP client for any interface whose name matches
any of the shell glob patterns in this list. Use this
option to prevent the DHCP client from broadcasting requests
on the yggdrasil network. It is only necessary to do so
when yggdrasil is running in TAP mode, because TUN
interfaces do not support broadcasting.
'';
};
package = mkOption {
type = package;
default = pkgs.yggdrasil;
defaultText = "pkgs.yggdrasil";
description = "Yggdrasil package to use.";
};
persistentKeys = mkEnableOption ''
If enabled then keys will be generated once and Yggdrasil
will retain the same IPv6 address when the service is
restarted. Keys are stored at ${keysPath}.
'';
};
};
config = mkIf cfg.enable (let binYggdrasil = cfg.package + "/bin/yggdrasil";
in {
assertions = [{
assertion = config.networking.enableIPv6;
message = "networking.enableIPv6 must be true for yggdrasil to work";
}];
system.activationScripts.yggdrasil = mkIf cfg.persistentKeys ''
if [ ! -e ${keysPath} ]
then
mkdir --mode=700 -p ${builtins.dirOf keysPath}
${binYggdrasil} -genconf -json \
| ${pkgs.jq}/bin/jq \
'to_entries|map(select(.key|endswith("Key")))|from_entries' \
> ${keysPath}
fi
'';
systemd.services.yggdrasil = {
description = "Yggdrasil Network Service";
bindsTo = [ "network-online.target" ];
after = [ "network-online.target" ];
wantedBy = [ "multi-user.target" ];
preStart =
(if configProvided || configFileProvided || cfg.persistentKeys then
"echo "
+ (lib.optionalString configProvided
"'${builtins.toJSON cfg.config}'")
+ (lib.optionalString configFileProvided "$(cat ${cfg.configFile})")
+ (lib.optionalString cfg.persistentKeys "$(cat ${keysPath})")
+ " | ${pkgs.jq}/bin/jq -s add | ${binYggdrasil} -normaliseconf -useconf"
else
"${binYggdrasil} -genconf") + " > /run/yggdrasil/yggdrasil.conf";
serviceConfig = {
ExecStart =
"${binYggdrasil} -useconffile /run/yggdrasil/yggdrasil.conf";
ExecReload = "${pkgs.coreutils}/bin/kill -HUP $MAINPID";
Restart = "always";
Group = cfg.group;
RuntimeDirectory = "yggdrasil";
RuntimeDirectoryMode = "0750";
BindReadOnlyPaths = lib.optional configFileProvided cfg.configFile
++ lib.optional cfg.persistentKeys keysPath;
# TODO: as of yggdrasil 0.3.8 and systemd 243, yggdrasil fails
# to set up the network adapter when DynamicUser is set. See
# github.com/yggdrasil-network/yggdrasil-go/issues/557. The
# following options are implied by DynamicUser according to
# the systemd.exec documentation, and can be removed if the
# upstream issue is fixed and DynamicUser is set to true:
PrivateTmp = true;
RemoveIPC = true;
NoNewPrivileges = true;
ProtectSystem = "strict";
RestrictSUIDSGID = true;
# End of list of options implied by DynamicUser.
AmbientCapabilities = "CAP_NET_ADMIN";
CapabilityBoundingSet = "CAP_NET_ADMIN";
MemoryDenyWriteExecute = true;
ProtectControlGroups = true;
ProtectHome = "tmpfs";
ProtectKernelModules = true;
ProtectKernelTunables = true;
RestrictAddressFamilies = "AF_UNIX AF_INET AF_INET6 AF_NETLINK";
RestrictNamespaces = true;
RestrictRealtime = true;
SystemCallArchitectures = "native";
SystemCallFilter = "~@clock @cpu-emulation @debug @keyring @module @mount @obsolete @raw-io @resources";
};
};
networking.dhcpcd.denyInterfaces = cfg.denyDhcpcdInterfaces;
networking.firewall.allowedUDPPorts = mkIf cfg.openMulticastPort [ 9001 ];
# Make yggdrasilctl available on the command line.
environment.systemPackages = [ cfg.package ];
});
meta = {
doc = ./yggdrasil.xml;
maintainers = with lib.maintainers; [ gazally ehmry ];
};
}