29027fd1e1
Using pkgs.lib on the spine of module evaluation is problematic because the pkgs argument depends on the result of module evaluation. To prevent an infinite recursion, pkgs and some of the modules are evaluated twice, which is inefficient. Using ‘with lib’ prevents this problem.
77 lines
2.5 KiB
Nix
77 lines
2.5 KiB
Nix
{ config, lib, pkgs, ... }:
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with lib;
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let
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sysctlOption = mkOptionType {
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name = "sysctl option value";
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check = x: isBool x || isString x || isInt x || isNull x;
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merge = args: defs: (last defs).value; # FIXME: hacky way to allow overriding in configuration.nix.
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};
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in
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{
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options = {
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boot.kernel.sysctl = mkOption {
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default = {};
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example = {
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"net.ipv4.tcp_syncookies" = false;
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"vm.swappiness" = 60;
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};
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type = types.attrsOf sysctlOption;
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description = ''
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Runtime parameters of the Linux kernel, as set by
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<citerefentry><refentrytitle>sysctl</refentrytitle>
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<manvolnum>8</manvolnum></citerefentry>. Note that sysctl
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parameters names must be enclosed in quotes
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(e.g. <literal>"vm.swappiness"</literal> instead of
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<literal>vm.swappiness</literal>). The value of each
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parameter may be a string, integer, boolean, or null
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(signifying the option will not appear at all).
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'';
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};
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};
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config = {
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environment.etc."sysctl.d/nixos.conf".text =
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concatStrings (mapAttrsToList (n: v:
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optionalString (v != null) "${n}=${if v == false then "0" else toString v}\n"
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) config.boot.kernel.sysctl);
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systemd.services.systemd-sysctl =
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{ description = "Apply Kernel Variables";
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before = [ "sysinit.target" "shutdown.target" ];
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wantedBy = [ "sysinit.target" "multi-user.target" ];
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restartTriggers = [ config.environment.etc."sysctl.d/nixos.conf".source ];
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unitConfig = {
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DefaultDependencies = false; # needed to prevent a cycle
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ConditionPathIsReadWrite = "/proc/sys/"; # prevent systemd-sysctl in containers
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};
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serviceConfig = {
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Type = "oneshot";
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RemainAfterExit = true;
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ExecStart = "${config.systemd.package}/lib/systemd/systemd-sysctl";
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};
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};
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# Enable hardlink and symlink restrictions. See
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# https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=800179c9b8a1e796e441674776d11cd4c05d61d7
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# for details.
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boot.kernel.sysctl."fs.protected_hardlinks" = true;
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boot.kernel.sysctl."fs.protected_symlinks" = true;
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# Hide kernel pointers (e.g. in /proc/modules) for unprivileged
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# users as these make it easier to exploit kernel vulnerabilities.
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#
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# Removed under grsecurity.
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boot.kernel.sysctl."kernel.kptr_restrict" =
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if config.security.grsecurity.enable then null else 1;
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};
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}
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