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nixpkgs/nixos/modules/programs/rust-motd.nix
Maximilian Bosch 0178db0da3
nixos/rust-motd: init
Makes it easier to configure `rust-motd`. Currently, it takes care of
the following things:

* Creating a timer to regularly refresh the `motd`-text and a hardened
  service (which is still root to get access to e.g. fs-mounts, but
  read-only because of hardening flags).
* Disabling `PrintLastLog` in `sshd.conf` if the last-login feature of
  `rust-motd` is supposed to be used.
* Ensure that the banner is actually shown when connecting via `ssh(1)`
  to a remote server with this being enabled.
2022-08-29 15:27:14 +02:00

93 lines
3 KiB
Nix

{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.programs.rust-motd;
format = pkgs.formats.toml { };
in {
options.programs.rust-motd = {
enable = mkEnableOption "rust-motd";
enableMotdInSSHD = mkOption {
default = true;
type = types.bool;
description = mdDoc ''
Whether to let `openssh` print the
result when entering a new `ssh`-session.
By default either nothing or a static file defined via
[](#opt-users.motd) is printed. Because of that,
the latter option is incompatible with this module.
'';
};
refreshInterval = mkOption {
default = "*:0/5";
type = types.str;
description = mdDoc ''
Interval in which the {manpage}`motd(5)` file is refreshed.
For possible formats, please refer to {manpage}`systemd.time(7)`.
'';
};
settings = mkOption {
type = types.submodule {
freeformType = format.type;
};
description = mdDoc ''
Settings on what to generate. Please read the
[upstream documentation](https://github.com/rust-motd/rust-motd/blob/main/README.md#configuration)
for further information.
'';
};
};
config = mkIf cfg.enable {
assertions = [
{ assertion = config.users.motd == null;
message = ''
`programs.rust-motd` is incompatible with `users.motd`!
'';
}
];
systemd.services.rust-motd = {
path = with pkgs; [ bash ];
documentation = [ "https://github.com/rust-motd/rust-motd/blob/v${pkgs.rust-motd.version}/README.md" ];
description = "motd generator";
serviceConfig = {
ExecStart = "${pkgs.writeShellScript "update-motd" ''
${pkgs.rust-motd}/bin/rust-motd ${format.generate "motd.conf" cfg.settings} > motd
''}";
CapabilityBoundingSet = [ "" ];
LockPersonality = true;
MemoryDenyWriteExecute = true;
NoNewPrivileges = true;
PrivateDevices = true;
PrivateTmp = true;
ProtectClock = true;
ProtectControlGroups = true;
ProtectHome = true;
ProtectHostname = true;
ProtectKernelModules = true;
ProtectKernelLogs = true;
ProtectKernelTunables = true;
ProtectSystem = "full";
StateDirectory = "rust-motd";
RestrictAddressFamilies = "none";
RestrictNamespaces = true;
RestrictRealtime = true;
RestrictSUIDSGID = true;
RemoveIPC = true;
WorkingDirectory = "/var/lib/rust-motd";
};
};
systemd.timers.rust-motd = {
wantedBy = [ "timers.target" ];
timerConfig.OnCalendar = cfg.refreshInterval;
};
security.pam.services.sshd.text = mkIf cfg.enableMotdInSSHD (mkDefault (mkAfter ''
session optional ${pkgs.pam}/lib/security/pam_motd.so motd=/var/lib/rust-motd/motd
''));
services.openssh.extraConfig = mkIf (cfg.settings ? last_login && cfg.settings.last_login != {}) ''
PrintLastLog no
'';
};
meta.maintainers = with maintainers; [ ma27 ];
}