64 lines
1.8 KiB
Nix
64 lines
1.8 KiB
Nix
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{ config, lib, pkgs, ... }:
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with lib;
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let
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cfg = config.security.rngd;
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in
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{
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options = {
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security.rngd = {
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enable = mkOption {
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type = types.bool;
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default = true;
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description = ''
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Whether to enable the rng daemon, which adds entropy from
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hardware sources of randomness to the kernel entropy pool when
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available.
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'';
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};
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debug = mkOption {
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type = types.bool;
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default = false;
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description = "Whether to enable debug output (-d).";
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};
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};
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};
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config = mkIf cfg.enable {
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services.udev.extraRules = ''
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KERNEL=="random", TAG+="systemd"
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SUBSYSTEM=="cpu", ENV{MODALIAS}=="cpu:type:x86,*feature:*009E*", TAG+="systemd", ENV{SYSTEMD_WANTS}+="rngd.service"
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KERNEL=="hw_random", TAG+="systemd", ENV{SYSTEMD_WANTS}+="rngd.service"
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'';
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systemd.services.rngd = {
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bindsTo = [ "dev-random.device" ];
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after = [ "dev-random.device" ];
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# Clean shutdown without DefaultDependencies
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conflicts = [ "shutdown.target" ];
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before = [
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"sysinit.target"
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"shutdown.target"
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];
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description = "Hardware RNG Entropy Gatherer Daemon";
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# rngd may have to start early to avoid entropy starvation during boot with encrypted swap
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unitConfig.DefaultDependencies = false;
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serviceConfig = {
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ExecStart = "${pkgs.rng-tools}/sbin/rngd -f"
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+ optionalString cfg.debug " -d";
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# PrivateTmp would introduce a circular dependency if /tmp is on tmpfs and swap is encrypted,
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# thus depending on rngd before swap, while swap depends on rngd to avoid entropy starvation.
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NoNewPrivileges = true;
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PrivateNetwork = true;
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ProtectSystem = "full";
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ProtectHome = true;
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};
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};
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};
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}
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