nixpkgs/nixos/modules/services/misc/home-assistant.nix
Martin Weinelt 24adc01e2e
nixos/home-assistant: allow netlink sockets and /proc/net inspection
Since v2021.5.0 home-assistant uses the ifaddr library in the zeroconf
component to enumerate network interfaces via netlink. Since discovery
is all over the place lets allow AF_NETLINK unconditionally.

It also relies on pyroute2 now, which additionally tries to access files
in /proc/net, so we relax ProtectProc a bit by default as well.

This leaves us with these options unsecured:

✗ PrivateNetwork=                                             Service has access to the host's network                                                                 0.5
✗ RestrictAddressFamilies=~AF_(INET|INET6)                    Service may allocate Internet sockets                                                                    0.3
✗ DeviceAllow=                                                Service has a device ACL with some special devices                                                       0.1
✗ IPAddressDeny=                                              Service does not define an IP address allow list                                                         0.2
✗ PrivateDevices=                                             Service potentially has access to hardware devices                                                       0.2
✗ PrivateUsers=                                               Service has access to other users                                                                        0.2
✗ SystemCallFilter=~@resources                                System call allow list defined for service, and @resources is included (e.g. ioprio_set is allowed)      0.2
✗ RestrictAddressFamilies=~AF_NETLINK                         Service may allocate netlink sockets                                                                     0.1
✗ RootDirectory=/RootImage=                                   Service runs within the host's root directory                                                            0.1
✗ SupplementaryGroups=                                        Service runs with supplementary groups                                                                   0.1
✗ RestrictAddressFamilies=~AF_UNIX                            Service may allocate local sockets                                                                       0.1
✗ ProcSubset=                                                 Service has full access to non-process /proc files (/proc subset=)                                       0.1

→ Overall exposure level for home-assistant.service: 1.6 OK 🙂
2021-05-06 16:55:53 +02:00

351 lines
13 KiB
Nix

{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.services.home-assistant;
# cfg.config != null can be assumed here
configJSON = pkgs.writeText "configuration.json"
(builtins.toJSON (if cfg.applyDefaultConfig then
(recursiveUpdate defaultConfig cfg.config) else cfg.config));
configFile = pkgs.runCommand "configuration.yaml" { preferLocalBuild = true; } ''
${pkgs.remarshal}/bin/json2yaml -i ${configJSON} -o $out
# Hack to support custom yaml objects,
# i.e. secrets: https://www.home-assistant.io/docs/configuration/secrets/
sed -i -e "s/'\!\([a-z_]\+\) \(.*\)'/\!\1 \2/;s/^\!\!/\!/;" $out
'';
lovelaceConfigJSON = pkgs.writeText "ui-lovelace.json"
(builtins.toJSON cfg.lovelaceConfig);
lovelaceConfigFile = pkgs.runCommand "ui-lovelace.yaml" { preferLocalBuild = true; } ''
${pkgs.remarshal}/bin/json2yaml -i ${lovelaceConfigJSON} -o $out
'';
availableComponents = cfg.package.availableComponents;
usedPlatforms = config:
if isAttrs config then
optional (config ? platform) config.platform
++ concatMap usedPlatforms (attrValues config)
else if isList config then
concatMap usedPlatforms config
else [ ];
# Given a component "platform", looks up whether it is used in the config
# as `platform = "platform";`.
#
# For example, the component mqtt.sensor is used as follows:
# config.sensor = [ {
# platform = "mqtt";
# ...
# } ];
useComponentPlatform = component: elem component (usedPlatforms cfg.config);
# Returns whether component is used in config
useComponent = component:
hasAttrByPath (splitString "." component) cfg.config
|| useComponentPlatform component;
# List of components used in config
extraComponents = filter useComponent availableComponents;
package = if (cfg.autoExtraComponents && cfg.config != null)
then (cfg.package.override { inherit extraComponents; })
else cfg.package;
# If you are changing this, please update the description in applyDefaultConfig
defaultConfig = {
homeassistant.time_zone = config.time.timeZone;
http.server_port = cfg.port;
} // optionalAttrs (cfg.lovelaceConfig != null) {
lovelace.mode = "yaml";
};
in {
meta.maintainers = teams.home-assistant.members;
options.services.home-assistant = {
enable = mkEnableOption "Home Assistant";
configDir = mkOption {
default = "/var/lib/hass";
type = types.path;
description = "The config directory, where your <filename>configuration.yaml</filename> is located.";
};
port = mkOption {
default = 8123;
type = types.int;
description = "The port on which to listen.";
};
applyDefaultConfig = mkOption {
default = true;
type = types.bool;
description = ''
Setting this option enables a few configuration options for HA based on NixOS configuration (such as time zone) to avoid having to manually specify configuration we already have.
</para>
<para>
Currently one side effect of enabling this is that the <literal>http</literal> component will be enabled.
</para>
<para>
This only takes effect if <literal>config != null</literal> in order to ensure that a manually managed <filename>configuration.yaml</filename> is not overwritten.
'';
};
config = mkOption {
default = null;
# Migrate to new option types later: https://github.com/NixOS/nixpkgs/pull/75584
type = with lib.types; let
valueType = nullOr (oneOf [
bool
int
float
str
(lazyAttrsOf valueType)
(listOf valueType)
]) // {
description = "Yaml value";
emptyValue.value = {};
};
in valueType;
example = literalExample ''
{
homeassistant = {
name = "Home";
latitude = "!secret latitude";
longitude = "!secret longitude";
elevation = "!secret elevation";
unit_system = "metric";
time_zone = "UTC";
};
frontend = {
themes = "!include_dir_merge_named themes";
};
http = { };
feedreader.urls = [ "https://nixos.org/blogs.xml" ];
}
'';
description = ''
Your <filename>configuration.yaml</filename> as a Nix attribute set.
Beware that setting this option will delete your previous <filename>configuration.yaml</filename>.
<link xlink:href="https://www.home-assistant.io/docs/configuration/secrets/">Secrets</link>
are encoded as strings as shown in the example.
'';
};
configWritable = mkOption {
default = false;
type = types.bool;
description = ''
Whether to make <filename>configuration.yaml</filename> writable.
This only has an effect if <option>config</option> is set.
This will allow you to edit it from Home Assistant's web interface.
However, bear in mind that it will be overwritten at every start of the service.
'';
};
lovelaceConfig = mkOption {
default = null;
type = with types; nullOr attrs;
# from https://www.home-assistant.io/lovelace/yaml-mode/
example = literalExample ''
{
title = "My Awesome Home";
views = [ {
title = "Example";
cards = [ {
type = "markdown";
title = "Lovelace";
content = "Welcome to your **Lovelace UI**.";
} ];
} ];
}
'';
description = ''
Your <filename>ui-lovelace.yaml</filename> as a Nix attribute set.
Setting this option will automatically add
<literal>lovelace.mode = "yaml";</literal> to your <option>config</option>.
Beware that setting this option will delete your previous <filename>ui-lovelace.yaml</filename>
'';
};
lovelaceConfigWritable = mkOption {
default = false;
type = types.bool;
description = ''
Whether to make <filename>ui-lovelace.yaml</filename> writable.
This only has an effect if <option>lovelaceConfig</option> is set.
This will allow you to edit it from Home Assistant's web interface.
However, bear in mind that it will be overwritten at every start of the service.
'';
};
package = mkOption {
default = pkgs.home-assistant.overrideAttrs (oldAttrs: {
doInstallCheck = false;
});
defaultText = literalExample ''
pkgs.home-assistant.overrideAttrs (oldAttrs: {
doInstallCheck = false;
})
'';
type = types.package;
example = literalExample ''
pkgs.home-assistant.override {
extraPackages = ps: with ps; [ colorlog ];
}
'';
description = ''
Home Assistant package to use. By default the tests are disabled, as they take a considerable amout of time to complete.
Override <literal>extraPackages</literal> or <literal>extraComponents</literal> in order to add additional dependencies.
If you specify <option>config</option> and do not set <option>autoExtraComponents</option>
to <literal>false</literal>, overriding <literal>extraComponents</literal> will have no effect.
Avoid <literal>home-assistant.overridePythonAttrs</literal> if you use <literal>autoExtraComponents</literal>.
'';
};
autoExtraComponents = mkOption {
default = true;
type = types.bool;
description = ''
If set to <literal>true</literal>, the components used in <literal>config</literal>
are set as the specified package's <literal>extraComponents</literal>.
This in turn adds all packaged dependencies to the derivation.
You might still see import errors in your log.
In this case, you will need to package the necessary dependencies yourself
or ask for someone else to package them.
If a dependency is packaged but not automatically added to this list,
you might need to specify it in <literal>extraPackages</literal>.
'';
};
openFirewall = mkOption {
default = false;
type = types.bool;
description = "Whether to open the firewall for the specified port.";
};
};
config = mkIf cfg.enable {
networking.firewall.allowedTCPPorts = mkIf cfg.openFirewall [ cfg.port ];
systemd.services.home-assistant = {
description = "Home Assistant";
after = [ "network.target" ];
preStart = optionalString (cfg.config != null) (if cfg.configWritable then ''
cp --no-preserve=mode ${configFile} "${cfg.configDir}/configuration.yaml"
'' else ''
rm -f "${cfg.configDir}/configuration.yaml"
ln -s ${configFile} "${cfg.configDir}/configuration.yaml"
'') + optionalString (cfg.lovelaceConfig != null) (if cfg.lovelaceConfigWritable then ''
cp --no-preserve=mode ${lovelaceConfigFile} "${cfg.configDir}/ui-lovelace.yaml"
'' else ''
rm -f "${cfg.configDir}/ui-lovelace.yaml"
ln -s ${lovelaceConfigFile} "${cfg.configDir}/ui-lovelace.yaml"
'');
serviceConfig = let
# List of capabilities to equip home-assistant with, depending on configured components
capabilities = [
# Empty string first, so we will never accidentally have an empty capability bounding set
# https://github.com/NixOS/nixpkgs/issues/120617#issuecomment-830685115
""
] ++ (unique (optionals (useComponent "bluetooth_tracker" || useComponent "bluetooth_le_tracker") [
# Required for interaction with hci devices and bluetooth sockets
# https://www.home-assistant.io/integrations/bluetooth_le_tracker/#rootless-setup-on-core-installs
"CAP_NET_ADMIN"
"CAP_NET_RAW"
] ++ lib.optionals (useComponent "emulated_hue") [
# Alexa looks for the service on port 80
# https://www.home-assistant.io/integrations/emulated_hue
"CAP_NET_BIND_SERVICE"
] ++ lib.optionals (useComponent "nmap_tracker") [
# https://www.home-assistant.io/integrations/nmap_tracker#linux-capabilities
"CAP_NET_ADMIN"
"CAP_NET_BIND_SERVICE"
"CAP_NET_RAW"
]));
in {
ExecStart = "${package}/bin/hass --runner --config '${cfg.configDir}'";
ExecReload = "${pkgs.coreutils}/bin/kill -HUP $MAINPID";
User = "hass";
Group = "hass";
Restart = "on-failure";
RestartForceExitStatus = "100";
SuccessExitStatus = "100";
KillSignal = "SIGINT";
# Hardening
AmbientCapabilities = capabilities;
CapabilityBoundingSet = capabilities;
DeviceAllow = [
"char-ttyACM rw"
"char-ttyAMA rw"
"char-ttyUSB rw"
];
DevicePolicy = "closed";
LockPersonality = true;
MemoryDenyWriteExecute = true;
NoNewPrivileges = true;
PrivateTmp = true;
PrivateUsers = false; # prevents gaining capabilities in the host namespace
ProtectClock = true;
ProtectControlGroups = true;
ProtectHome = true;
ProtectHostname = true;
ProtectKernelLogs = true;
ProtectKernelModules = true;
ProtectKernelTunables = true;
ProtectProc = "invisible";
ProcSubset = "all";
ProtectSystem = "strict";
RemoveIPC = true;
ReadWritePaths = let
# Allow rw access to explicitly configured paths
cfgPath = [ "config" "homeassistant" "allowlist_external_dirs" ];
value = attrByPath cfgPath [] cfg;
allowPaths = if isList value then value else singleton value;
in [ "${cfg.configDir}" ] ++ allowPaths;
RestrictAddressFamilies = [
"AF_INET"
"AF_INET6"
"AF_NETLINK"
"AF_UNIX"
] ++ optionals (useComponent "bluetooth_tracker" || useComponent "bluetooth_le_tracker") [
"AF_BLUETOOTH"
];
RestrictNamespaces = true;
RestrictRealtime = true;
RestrictSUIDSGID = true;
SupplementaryGroups = [ "dialout" ];
SystemCallArchitectures = "native";
SystemCallFilter = [
"@system-service"
"~@privileged"
];
UMask = "0077";
};
path = [
"/run/wrappers" # needed for ping
];
};
systemd.targets.home-assistant = rec {
description = "Home Assistant";
wantedBy = [ "multi-user.target" ];
wants = [ "home-assistant.service" ];
after = wants;
};
users.users.hass = {
home = cfg.configDir;
createHome = true;
group = "hass";
uid = config.ids.uids.hass;
};
users.groups.hass.gid = config.ids.gids.hass;
};
}