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nixos/modules/networking/wg-quick Add wg-quick options support
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This is an implementation of wireguard support using wg-quick config
generation.

This seems preferrable to the existing wireguard support because
it handles many more routing and resolvconf edge cases than the
current wireguard support.

It also includes work-arounds to make key files work.

This has one quirk:
We need to set reverse path checking in the firewall to false because
it interferes with the way wg-quick sets up its routing.
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@exi
exi committed Apr 20, 2019
1 parent f246230 commit abf6079
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1 change: 1 addition & 0 deletions nixos/modules/module-list.nix
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./services/networking/vsftpd.nix
./services/networking/wakeonlan.nix
./services/networking/websockify.nix
./services/networking/wg-quick.nix
./services/networking/wicd.nix
./services/networking/wireguard.nix
./services/networking/wpa_supplicant.nix
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312 changes: 312 additions & 0 deletions nixos/modules/services/networking/wg-quick.nix
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{ config, lib, pkgs, ... }:

with lib;
let
cfg = config.networking.wg-quick;

kernel = config.boot.kernelPackages;

# interface options

interfaceOpts = { ... }: {
options = {
address = mkOption {
example = [ "192.168.2.1/24" ];
default = [];
type = with types; listOf str;
description = "The IP addresses of the interface.";
};

dns = mkOption {
example = [ "192.168.2.2" ];
default = [];
type = with types; listOf str;
description = "The IP addresses of DNS servers to configure.";
};

privateKey = mkOption {
example = "yAnz5TF+lXXJte14tji3zlMNq+hd2rYUIgJBgB3fBmk=";
type = with types; nullOr str;
default = null;
description = ''
Base64 private key generated by wg genkey.
Warning: Consider using privateKeyFile instead if you do not
want to store the key in the world-readable Nix store.
'';
};

privateKeyFile = mkOption {
example = "/private/wireguard_key";
type = with types; nullOr str;
default = null;
description = ''
Private key file as generated by wg genkey.
'';
};

listenPort = mkOption {
default = null;
type = with types; nullOr int;
example = 51820;
description = ''
16-bit port for listening. Optional; if not specified,
automatically generated based on interface name.
'';
};

preUp = mkOption {
example = literalExample ''
${pkgs.iproute}/bin/ip netns add foo
'';
default = "";
type = with types; coercedTo (listOf str) (concatStringsSep "\n") lines;
description = ''
Commands called at the start of the interface setup.
'';
};

preDown = mkOption {
example = literalExample ''
${pkgs.iproute}/bin/ip netns del foo
'';
default = "";
type = with types; coercedTo (listOf str) (concatStringsSep "\n") lines;
description = ''
Command called before the interface is taken down.
'';
};

postUp = mkOption {
example = literalExample ''
${pkgs.iproute}/bin/ip netns add foo
'';
default = "";
type = with types; coercedTo (listOf str) (concatStringsSep "\n") lines;
description = ''
Commands called after the interface setup.
'';
};

postDown = mkOption {
example = literalExample ''
${pkgs.iproute}/bin/ip netns del foo
'';
default = "";
type = with types; coercedTo (listOf str) (concatStringsSep "\n") lines;
description = ''
Command called after the interface is taken down.
'';
};

table = mkOption {
example = "main";
default = null;
type = with types; nullOr str;
description = ''
The kernel routing table to add this interface's
associated routes to. Setting this is useful for e.g. policy routing
("ip rule") or virtual routing and forwarding ("ip vrf"). Both numeric
table IDs and table names (/etc/rt_tables) can be used. Defaults to
"main".
'';
};

mtu = mkOption {
example = 1248;
default = null;
type = with types; nullOr int;
description = ''
If not specified, the MTU is automatically determined
from the endpoint addresses or the system default route, which is usually
a sane choice. However, to manually specify an MTU to override this
automatic discovery, this value may be specified explicitly.
'';
};

peers = mkOption {
default = [];
description = "Peers linked to the interface.";
type = with types; listOf (submodule peerOpts);
};
};
};

# peer options

peerOpts = {
options = {
publicKey = mkOption {
example = "xTIBA5rboUvnH4htodjb6e697QjLERt1NAB4mZqp8Dg=";
type = types.str;
description = "The base64 public key the peer.";
};

presharedKey = mkOption {
default = null;
example = "rVXs/Ni9tu3oDBLS4hOyAUAa1qTWVA3loR8eL20os3I=";
type = with types; nullOr str;
description = ''
Base64 preshared key generated by wg genpsk. Optional,
and may be omitted. This option adds an additional layer of
symmetric-key cryptography to be mixed into the already existing
public-key cryptography, for post-quantum resistance.
Warning: Consider using presharedKeyFile instead if you do not
want to store the key in the world-readable Nix store.
'';
};

presharedKeyFile = mkOption {
default = null;
example = "/private/wireguard_psk";
type = with types; nullOr str;
description = ''
File pointing to preshared key as generated by wg pensk. Optional,
and may be omitted. This option adds an additional layer of
symmetric-key cryptography to be mixed into the already existing
public-key cryptography, for post-quantum resistance.
'';
};

allowedIPs = mkOption {
example = [ "10.192.122.3/32" "10.192.124.1/24" ];
type = with types; listOf str;
description = ''List of IP (v4 or v6) addresses with CIDR masks from
which this peer is allowed to send incoming traffic and to which
outgoing traffic for this peer is directed. The catch-all 0.0.0.0/0 may
be specified for matching all IPv4 addresses, and ::/0 may be specified
for matching all IPv6 addresses.'';
};

endpoint = mkOption {
default = null;
example = "demo.wireguard.io:12913";
type = with types; nullOr str;
description = ''Endpoint IP or hostname of the peer, followed by a colon,
and then a port number of the peer.'';
};

persistentKeepalive = mkOption {
default = null;
type = with types; nullOr int;
example = 25;
description = ''This is optional and is by default off, because most
users will not need it. It represents, in seconds, between 1 and 65535
inclusive, how often to send an authenticated empty packet to the peer,
for the purpose of keeping a stateful firewall or NAT mapping valid
persistently. For example, if the interface very rarely sends traffic,
but it might at anytime receive traffic from a peer, and it is behind
NAT, the interface might benefit from having a persistent keepalive
interval of 25 seconds; however, most users will not need this.'';
};
};
};

writeScriptFile = name: text: ((pkgs.writeShellScriptBin name text) + "/bin/${name}");

generateUnit = name: values:
assert assertMsg ((values.privateKey != null) != (values.privateKeyFile != null)) "Only one of privateKey or privateKeyFile may be set";
let
preUpFile = if values.preUp != "" then writeScriptFile "preUp.sh" values.preUp else null;
postUp =
optional (values.privateKeyFile != null) "wg set ${name} private-key <(cat ${values.privateKeyFile})" ++
(concatMap (peer: optional (peer.presharedKeyFile != null) "wg set ${name} peer ${peer.publicKey} preshared-key <(cat ${peer.presharedKeyFile})") values.peers) ++
optional (values.postUp != null) values.postUp;
postUpFile = if postUp != [] then writeScriptFile "postUp.sh" (concatMapStringsSep "\n" (line: line) postUp) else null;
preDownFile = if values.preDown != "" then writeScriptFile "preDown.sh" values.preDown else null;
postDownFile = if values.postDown != "" then writeScriptFile "postDown.sh" values.postDown else null;
configDir = pkgs.writeTextFile {
name = "config-${name}";
executable = false;
destination = "/${name}.conf";
text =
''
[interface]
${concatMapStringsSep "\n" (address:
"Address = ${address}"
) values.address}
${concatMapStringsSep "\n" (dns:
"DNS = ${dns}"
) values.dns}
'' +
optionalString (values.table != null) "Table = ${values.table}\n" +
optionalString (values.mtu != null) "MTU = ${toString values.mtu}\n" +
optionalString (values.privateKey != null) "PrivateKey = ${values.privateKey}\n" +
optionalString (values.listenPort != null) "ListenPort = ${toString values.listenPort}\n" +
optionalString (preUpFile != null) "PreUp = ${preUpFile}\n" +
optionalString (postUpFile != null) "PostUp = ${postUpFile}\n" +
optionalString (preDownFile != null) "PreDown = ${preDownFile}\n" +
optionalString (postDownFile != null) "PostDown = ${postDownFile}\n" +
concatMapStringsSep "\n" (peer:
assert assertMsg (!((peer.presharedKeyFile != null) && (peer.presharedKey != null))) "Only one of presharedKey or presharedKeyFile may be set";
"[Peer]\n" +
"PublicKey = ${peer.publicKey}\n" +
optionalString (peer.presharedKey != null) "PresharedKey = ${peer.presharedKey}\n" +
optionalString (peer.endpoint != null) "Endpoint = ${peer.endpoint}\n" +
optionalString (peer.persistentKeepalive != null) "PersistentKeepalive = ${toString peer.persistentKeepalive}\n" +
optionalString (peer.allowedIPs != []) "AllowedIPs = ${concatStringsSep "," peer.allowedIPs}\n"
) values.peers;
};
configPath = "${configDir}/${name}.conf";
in
nameValuePair "wg-quick-${name}"
{
description = "wg-quick WireGuard Tunnel - ${name}";
requires = [ "network-online.target" ];
after = [ "network.target" "network-online.target" ];
wantedBy = [ "multi-user.target" ];
environment.DEVICE = name;
path = [ pkgs.kmod pkgs.wireguard-tools ];

serviceConfig = {
Type = "oneshot";
RemainAfterExit = true;
};

script = ''
${optionalString (!config.boot.isContainer) "modprobe wireguard"}
wg-quick up ${configPath}
'';

preStop = ''
wg-quick down ${configPath}
'';
};
in {

###### interface

options = {
networking.wg-quick = {
interfaces = mkOption {
description = "Wireguard interfaces.";
default = {};
example = {
wg0 = {
address = [ "192.168.20.4/24" ];
privateKey = "yAnz5TF+lXXJte14tji3zlMNq+hd2rYUIgJBgB3fBmk=";
peers = [
{ allowedIPs = [ "192.168.20.1/32" ];
publicKey = "xTIBA5rboUvnH4htodjb6e697QjLERt1NAB4mZqp8Dg=";
endpoint = "demo.wireguard.io:12913"; }
];
};
};
type = with types; attrsOf (submodule interfaceOpts);
};
};
};


###### implementation

config = mkIf (cfg.interfaces != {}) {
boot.extraModulePackages = [ kernel.wireguard ];
environment.systemPackages = [ pkgs.wireguard-tools ];
# This is forced to false for now because the default "--validmark" rpfilter we apply on reverse path filtering
# breaks the wg-quick routing because wireguard packets leave with a fwmark from wireguard.
networking.firewall.checkReversePath = false;
systemd.services = mapAttrs' generateUnit cfg.interfaces;
};
}

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