nixpkgs/nixos/modules/system/boot/initrd-openvpn.nix
CRTified c684398c6a nixos/system/boot/initrd-openvpn: Add openvpn options for initrd
nixos/tests/initrd-openvpn: Add test for openvpn in the initramfs

The module in this commit adds new options that allows the
integration of an OpenVPN client into the initrd.
This can be used e.g. to remotely unlock LUKS devices.

This commit also adds two tests for `boot.initrd.network.openvpn`.
The first one is a basic test to validate that a failing connection
does not prevent the machine from booting.

The second test validates that this module actually creates a valid
openvpn connection.
For this, it spawns three nodes:

  - The client that uses boot.initrd.network.openvpn
  - An OpenVPN server that acts as gateway and forwards a port
    to the client
  - A node that is external to the OpenVPN network

The client connects to the OpenVPN server and spawns a netcat instance
that echos a value to every client.
Afterwards, the external node checks if it receives this value over the
forwarded port on the OpenVPN gateway.
2020-07-01 00:08:55 +02:00

82 lines
2.1 KiB
Nix

{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.boot.initrd.network.openvpn;
in
{
options = {
boot.initrd.network.openvpn.enable = mkOption {
type = types.bool;
default = false;
description = ''
Starts an OpenVPN client during initrd boot. It can be used to e.g.
remotely accessing the SSH service controlled by
<option>boot.initrd.network.ssh</option> or other network services
included. Service is killed when stage-1 boot is finished.
'';
};
boot.initrd.network.openvpn.configuration = mkOption {
type = types.path; # Same type as boot.initrd.secrets
description = ''
The configuration file for OpenVPN.
<warning>
<para>
Unless your bootloader supports initrd secrets, this configuration
is stored insecurely in the global Nix store.
</para>
</warning>
'';
example = "./configuration.ovpn";
};
};
config = mkIf (config.boot.initrd.network.enable && cfg.enable) {
assertions = [
{
assertion = cfg.configuration != null;
message = "You should specify a configuration for initrd OpenVPN";
}
];
# Add kernel modules needed for OpenVPN
boot.initrd.kernelModules = [ "tun" "tap" ];
# Add openvpn and ip binaries to the initrd
# The shared libraries are required for DNS resolution
boot.initrd.extraUtilsCommands = ''
copy_bin_and_libs ${pkgs.openvpn}/bin/openvpn
copy_bin_and_libs ${pkgs.iproute}/bin/ip
cp -pv ${pkgs.glibc}/lib/libresolv.so.2 $out/lib
cp -pv ${pkgs.glibc}/lib/libnss_dns.so.2 $out/lib
'';
boot.initrd.secrets = {
"/etc/initrd.ovpn" = cfg.configuration;
};
# openvpn --version would exit with 1 instead of 0
boot.initrd.extraUtilsCommandsTest = ''
$out/bin/openvpn --show-gateway
'';
# Add `iproute /bin/ip` to the config, to ensure that openvpn
# is able to set the routes
boot.initrd.network.postCommands = ''
(cat /etc/initrd.ovpn; echo -e '\niproute /bin/ip') | \
openvpn /dev/stdin &
'';
};
}