nixpkgs/nixos/modules/services/networking/wpa_supplicant.nix
nicoo a351c9b530 nixos/wpa_supplicant: Ensure the generated config isn't world-readable
Otherwise, `environmentFile` cannot be used to pass secrets in.
2023-12-09 21:33:55 +00:00

539 lines
19 KiB
Nix

{ config, lib, options, pkgs, utils, ... }:
with lib;
let
package = if cfg.allowAuxiliaryImperativeNetworks
then pkgs.wpa_supplicant_ro_ssids
else pkgs.wpa_supplicant;
cfg = config.networking.wireless;
opt = options.networking.wireless;
wpa3Protocols = [ "SAE" "FT-SAE" ];
hasMixedWPA = opts:
let
hasWPA3 = !mutuallyExclusive opts.authProtocols wpa3Protocols;
others = subtractLists wpa3Protocols opts.authProtocols;
in hasWPA3 && others != [];
# Gives a WPA3 network higher priority
increaseWPA3Priority = opts:
opts // optionalAttrs (hasMixedWPA opts)
{ priority = if opts.priority == null
then 1
else opts.priority + 1;
};
# Creates a WPA2 fallback network
mkWPA2Fallback = opts:
opts // { authProtocols = subtractLists wpa3Protocols opts.authProtocols; };
# Networks attrset as a list
networkList = mapAttrsToList (ssid: opts: opts // { inherit ssid; })
cfg.networks;
# List of all networks (normal + generated fallbacks)
allNetworks =
if cfg.fallbackToWPA2
then map increaseWPA3Priority networkList
++ map mkWPA2Fallback (filter hasMixedWPA networkList)
else networkList;
# Content of wpa_supplicant.conf
generatedConfig = concatStringsSep "\n" (
(map mkNetwork allNetworks)
++ optional cfg.userControlled.enable (concatStringsSep "\n"
[ "ctrl_interface=/run/wpa_supplicant"
"ctrl_interface_group=${cfg.userControlled.group}"
"update_config=1"
])
++ [ "pmf=1" ]
++ optional cfg.scanOnLowSignal ''bgscan="simple:30:-70:3600"''
++ optional (cfg.extraConfig != "") cfg.extraConfig);
configIsGenerated = with cfg;
networks != {} || extraConfig != "" || userControlled.enable;
# the original configuration file
configFile =
if configIsGenerated
then pkgs.writeText "wpa_supplicant.conf" generatedConfig
else "/etc/wpa_supplicant.conf";
# the config file with environment variables replaced
finalConfig = ''"$RUNTIME_DIRECTORY"/wpa_supplicant.conf'';
# Creates a network block for wpa_supplicant.conf
mkNetwork = opts:
let
quote = x: ''"${x}"'';
indent = x: " " + x;
pskString = if opts.psk != null
then quote opts.psk
else opts.pskRaw;
options = [
"ssid=${quote opts.ssid}"
(if pskString != null || opts.auth != null
then "key_mgmt=${concatStringsSep " " opts.authProtocols}"
else "key_mgmt=NONE")
] ++ optional opts.hidden "scan_ssid=1"
++ optional (pskString != null) "psk=${pskString}"
++ optionals (opts.auth != null) (filter (x: x != "") (splitString "\n" opts.auth))
++ optional (opts.priority != null) "priority=${toString opts.priority}"
++ optional (opts.extraConfig != "") opts.extraConfig;
in ''
network={
${concatMapStringsSep "\n" indent options}
}
'';
# Creates a systemd unit for wpa_supplicant bound to a given (or any) interface
mkUnit = iface:
let
deviceUnit = optional (iface != null) "sys-subsystem-net-devices-${utils.escapeSystemdPath iface}.device";
configStr = if cfg.allowAuxiliaryImperativeNetworks
then "-c /etc/wpa_supplicant.conf -I ${finalConfig}"
else "-c ${finalConfig}";
in {
description = "WPA Supplicant instance" + optionalString (iface != null) " for interface ${iface}";
after = deviceUnit;
before = [ "network.target" ];
wants = [ "network.target" ];
requires = deviceUnit;
wantedBy = [ "multi-user.target" ];
stopIfChanged = false;
path = [ package ];
# if `userControl.enable`, the supplicant automatically changes the permissions
# and owning group of the runtime dir; setting `umask` ensures the generated
# config file isn't readable (except to root); see nixpkgs#267693
serviceConfig.UMask = "066";
serviceConfig.RuntimeDirectory = "wpa_supplicant";
serviceConfig.RuntimeDirectoryMode = "700";
serviceConfig.EnvironmentFile = mkIf (cfg.environmentFile != null)
(builtins.toString cfg.environmentFile);
script =
''
${optionalString (configIsGenerated && !cfg.allowAuxiliaryImperativeNetworks) ''
if [ -f /etc/wpa_supplicant.conf ]; then
echo >&2 "<3>/etc/wpa_supplicant.conf present but ignored. Generated ${configFile} is used instead."
fi
''}
# substitute environment variables
if [ -f "${configFile}" ]; then
${pkgs.gawk}/bin/awk '{
for(varname in ENVIRON)
gsub("@"varname"@", ENVIRON[varname])
print
}' "${configFile}" > "${finalConfig}"
else
touch "${finalConfig}"
fi
iface_args="-s ${optionalString cfg.dbusControlled "-u"} -D${cfg.driver} ${configStr}"
${if iface == null then ''
# detect interfaces automatically
# check if there are no wireless interfaces
if ! find -H /sys/class/net/* -name wireless | grep -q .; then
# if so, wait until one appears
echo "Waiting for wireless interfaces"
grep -q '^ACTION=add' < <(stdbuf -oL -- udevadm monitor -s net/wlan -pu)
# Note: the above line has been carefully written:
# 1. The process substitution avoids udevadm hanging (after grep has quit)
# until it tries to write to the pipe again. Not even pipefail works here.
# 2. stdbuf is needed because udevadm output is buffered by default and grep
# may hang until more udev events enter the pipe.
fi
# add any interface found to the daemon arguments
for name in $(find -H /sys/class/net/* -name wireless | cut -d/ -f 5); do
echo "Adding interface $name"
args+="''${args:+ -N} -i$name $iface_args"
done
'' else ''
# add known interface to the daemon arguments
args="-i${iface} $iface_args"
''}
# finally start daemon
exec wpa_supplicant $args
'';
};
systemctl = "/run/current-system/systemd/bin/systemctl";
in {
options = {
networking.wireless = {
enable = mkEnableOption (lib.mdDoc "wpa_supplicant");
interfaces = mkOption {
type = types.listOf types.str;
default = [];
example = [ "wlan0" "wlan1" ];
description = lib.mdDoc ''
The interfaces {command}`wpa_supplicant` will use. If empty, it will
automatically use all wireless interfaces.
::: {.note}
A separate wpa_supplicant instance will be started for each interface.
:::
'';
};
driver = mkOption {
type = types.str;
default = "nl80211,wext";
description = lib.mdDoc "Force a specific wpa_supplicant driver.";
};
allowAuxiliaryImperativeNetworks = mkEnableOption (lib.mdDoc "support for imperative & declarative networks") // {
description = lib.mdDoc ''
Whether to allow configuring networks "imperatively" (e.g. via
`wpa_supplicant_gui`) and declaratively via
[](#opt-networking.wireless.networks).
Please note that this adds a custom patch to `wpa_supplicant`.
'';
};
scanOnLowSignal = mkOption {
type = types.bool;
default = true;
description = lib.mdDoc ''
Whether to periodically scan for (better) networks when the signal of
the current one is low. This will make roaming between access points
faster, but will consume more power.
'';
};
fallbackToWPA2 = mkOption {
type = types.bool;
default = true;
description = lib.mdDoc ''
Whether to fall back to WPA2 authentication protocols if WPA3 failed.
This allows old wireless cards (that lack recent features required by
WPA3) to connect to mixed WPA2/WPA3 access points.
To avoid possible downgrade attacks, disable this options.
'';
};
environmentFile = mkOption {
type = types.nullOr types.path;
default = null;
example = "/run/secrets/wireless.env";
description = lib.mdDoc ''
File consisting of lines of the form `varname=value`
to define variables for the wireless configuration.
See section "EnvironmentFile=" in {manpage}`systemd.exec(5)` for a syntax reference.
Secrets (PSKs, passwords, etc.) can be provided without adding them to
the world-readable Nix store by defining them in the environment file and
referring to them in option {option}`networking.wireless.networks`
with the syntax `@varname@`. Example:
```
# content of /run/secrets/wireless.env
PSK_HOME=mypassword
PASS_WORK=myworkpassword
```
```
# wireless-related configuration
networking.wireless.environmentFile = "/run/secrets/wireless.env";
networking.wireless.networks = {
home.psk = "@PSK_HOME@";
work.auth = '''
eap=PEAP
identity="my-user@example.com"
password="@PASS_WORK@"
''';
};
```
'';
};
networks = mkOption {
type = types.attrsOf (types.submodule {
options = {
psk = mkOption {
type = types.nullOr types.str;
default = null;
description = lib.mdDoc ''
The network's pre-shared key in plaintext defaulting
to being a network without any authentication.
::: {.warning}
Be aware that this will be written to the nix store
in plaintext! Use an environment variable instead.
:::
::: {.note}
Mutually exclusive with {var}`pskRaw`.
:::
'';
};
pskRaw = mkOption {
type = types.nullOr types.str;
default = null;
description = lib.mdDoc ''
The network's pre-shared key in hex defaulting
to being a network without any authentication.
::: {.warning}
Be aware that this will be written to the nix store
in plaintext! Use an environment variable instead.
:::
::: {.note}
Mutually exclusive with {var}`psk`.
:::
'';
};
authProtocols = mkOption {
default = [
# WPA2 and WPA3
"WPA-PSK" "WPA-EAP" "SAE"
# 802.11r variants of the above
"FT-PSK" "FT-EAP" "FT-SAE"
];
# The list can be obtained by running this command
# awk '
# /^# key_mgmt: /{ run=1 }
# /^#$/{ run=0 }
# /^# [A-Z0-9-]{2,}/{ if(run){printf("\"%s\"\n", $2)} }
# ' /run/current-system/sw/share/doc/wpa_supplicant/wpa_supplicant.conf.example
type = types.listOf (types.enum [
"WPA-PSK"
"WPA-EAP"
"IEEE8021X"
"NONE"
"WPA-NONE"
"FT-PSK"
"FT-EAP"
"FT-EAP-SHA384"
"WPA-PSK-SHA256"
"WPA-EAP-SHA256"
"SAE"
"FT-SAE"
"WPA-EAP-SUITE-B"
"WPA-EAP-SUITE-B-192"
"OSEN"
"FILS-SHA256"
"FILS-SHA384"
"FT-FILS-SHA256"
"FT-FILS-SHA384"
"OWE"
"DPP"
]);
description = lib.mdDoc ''
The list of authentication protocols accepted by this network.
This corresponds to the `key_mgmt` option in wpa_supplicant.
'';
};
auth = mkOption {
type = types.nullOr types.str;
default = null;
example = ''
eap=PEAP
identity="user@example.com"
password="@EXAMPLE_PASSWORD@"
'';
description = lib.mdDoc ''
Use this option to configure advanced authentication methods like EAP.
See
{manpage}`wpa_supplicant.conf(5)`
for example configurations.
::: {.warning}
Be aware that this will be written to the nix store
in plaintext! Use an environment variable for secrets.
:::
::: {.note}
Mutually exclusive with {var}`psk` and
{var}`pskRaw`.
:::
'';
};
hidden = mkOption {
type = types.bool;
default = false;
description = lib.mdDoc ''
Set this to `true` if the SSID of the network is hidden.
'';
example = literalExpression ''
{ echelon = {
hidden = true;
psk = "abcdefgh";
};
}
'';
};
priority = mkOption {
type = types.nullOr types.int;
default = null;
description = lib.mdDoc ''
By default, all networks will get same priority group (0). If some of the
networks are more desirable, this field can be used to change the order in
which wpa_supplicant goes through the networks when selecting a BSS. The
priority groups will be iterated in decreasing priority (i.e., the larger the
priority value, the sooner the network is matched against the scan results).
Within each priority group, networks will be selected based on security
policy, signal strength, etc.
'';
};
extraConfig = mkOption {
type = types.str;
default = "";
example = ''
bssid_blacklist=02:11:22:33:44:55 02:22:aa:44:55:66
'';
description = lib.mdDoc ''
Extra configuration lines appended to the network block.
See
{manpage}`wpa_supplicant.conf(5)`
for available options.
'';
};
};
});
description = lib.mdDoc ''
The network definitions to automatically connect to when
{command}`wpa_supplicant` is running. If this
parameter is left empty wpa_supplicant will use
/etc/wpa_supplicant.conf as the configuration file.
'';
default = {};
example = literalExpression ''
{ echelon = { # SSID with no spaces or special characters
psk = "abcdefgh"; # (password will be written to /nix/store!)
};
echelon = { # safe version of the above: read PSK from the
psk = "@PSK_ECHELON@"; # variable PSK_ECHELON, defined in environmentFile,
}; # this won't leak into /nix/store
"echelon's AP" = { # SSID with spaces and/or special characters
psk = "ijklmnop"; # (password will be written to /nix/store!)
};
"free.wifi" = {}; # Public wireless network
}
'';
};
userControlled = {
enable = mkOption {
type = types.bool;
default = false;
description = lib.mdDoc ''
Allow normal users to control wpa_supplicant through wpa_gui or wpa_cli.
This is useful for laptop users that switch networks a lot and don't want
to depend on a large package such as NetworkManager just to pick nearby
access points.
When using a declarative network specification you cannot persist any
settings via wpa_gui or wpa_cli.
'';
};
group = mkOption {
type = types.str;
default = "wheel";
example = "network";
description = lib.mdDoc "Members of this group can control wpa_supplicant.";
};
};
dbusControlled = mkOption {
type = types.bool;
default = lib.length cfg.interfaces < 2;
defaultText = literalExpression "length config.${opt.interfaces} < 2";
description = lib.mdDoc ''
Whether to enable the DBus control interface.
This is only needed when using NetworkManager or connman.
'';
};
extraConfig = mkOption {
type = types.str;
default = "";
example = ''
p2p_disabled=1
'';
description = lib.mdDoc ''
Extra lines appended to the configuration file.
See
{manpage}`wpa_supplicant.conf(5)`
for available options.
'';
};
};
};
config = mkIf cfg.enable {
assertions = flip mapAttrsToList cfg.networks (name: cfg: {
assertion = with cfg; count (x: x != null) [ psk pskRaw auth ] <= 1;
message = ''options networking.wireless."${name}".{psk,pskRaw,auth} are mutually exclusive'';
}) ++ [
{
assertion = length cfg.interfaces > 1 -> !cfg.dbusControlled;
message =
let daemon = if config.networking.networkmanager.enable then "NetworkManager" else
if config.services.connman.enable then "connman" else null;
n = toString (length cfg.interfaces);
in ''
It's not possible to run multiple wpa_supplicant instances with DBus support.
Note: you're seeing this error because `networking.wireless.interfaces` has
${n} entries, implying an equal number of wpa_supplicant instances.
'' + optionalString (daemon != null) ''
You don't need to change `networking.wireless.interfaces` when using ${daemon}:
in this case the interfaces will be configured automatically for you.
'';
}
];
hardware.wirelessRegulatoryDatabase = true;
environment.systemPackages = [ package ];
services.dbus.packages = optional cfg.dbusControlled package;
systemd.services =
if cfg.interfaces == []
then { wpa_supplicant = mkUnit null; }
else listToAttrs (map (i: nameValuePair "wpa_supplicant-${i}" (mkUnit i)) cfg.interfaces);
# Restart wpa_supplicant after resuming from sleep
powerManagement.resumeCommands = concatStringsSep "\n" (
optional (cfg.interfaces == []) "${systemctl} try-restart wpa_supplicant"
++ map (i: "${systemctl} try-restart wpa_supplicant-${i}") cfg.interfaces
);
# Restart wpa_supplicant when a wlan device appears or disappears. This is
# only needed when an interface hasn't been specified by the user.
services.udev.extraRules = optionalString (cfg.interfaces == []) ''
ACTION=="add|remove", SUBSYSTEM=="net", ENV{DEVTYPE}=="wlan", \
RUN+="${systemctl} try-restart wpa_supplicant.service"
'';
};
meta.maintainers = with lib.maintainers; [ rnhmjoj ];
}