nixpkgs/nixos/modules/config/sysctl.nix
Ricardo M. Correia d8b21c2224 nixos: Fix sysctl option merging
Using pkgs.lib.mkOverride in a sysctl option would throw a bogus error.

Also, if you defined a sysctl multiple times in the same configuration,
only one of the values would be picked up, while the others were silently
discarded.

This patch should fix both issues. If you define a sysctl multiple
times at your highest defined priority level, you will get a proper
error with detailed location information.
2014-04-15 21:52:04 +02:00

81 lines
2.5 KiB
Nix

{ config, lib, pkgs, ... }:
with lib;
let
sysctlOption = mkOptionType {
name = "sysctl option value";
check = val:
let
checkType = x: isBool x || isString x || isInt x || isNull x;
in
checkType val || (val._type or "" == "override" && checkType val.content);
merge = loc: defs: mergeOneOption loc (filterOverrides defs);
};
in
{
options = {
boot.kernel.sysctl = mkOption {
default = {};
example = {
"net.ipv4.tcp_syncookies" = false;
"vm.swappiness" = 60;
};
type = types.attrsOf sysctlOption;
description = ''
Runtime parameters of the Linux kernel, as set by
<citerefentry><refentrytitle>sysctl</refentrytitle>
<manvolnum>8</manvolnum></citerefentry>. Note that sysctl
parameters names must be enclosed in quotes
(e.g. <literal>"vm.swappiness"</literal> instead of
<literal>vm.swappiness</literal>). The value of each
parameter may be a string, integer, boolean, or null
(signifying the option will not appear at all).
'';
};
};
config = {
environment.etc."sysctl.d/nixos.conf".text =
concatStrings (mapAttrsToList (n: v:
optionalString (v != null) "${n}=${if v == false then "0" else toString v}\n"
) config.boot.kernel.sysctl);
systemd.services.systemd-sysctl =
{ description = "Apply Kernel Variables";
before = [ "sysinit.target" "shutdown.target" ];
wantedBy = [ "sysinit.target" "multi-user.target" ];
restartTriggers = [ config.environment.etc."sysctl.d/nixos.conf".source ];
unitConfig = {
DefaultDependencies = false; # needed to prevent a cycle
ConditionPathIsReadWrite = "/proc/sys/"; # prevent systemd-sysctl in containers
};
serviceConfig = {
Type = "oneshot";
RemainAfterExit = true;
ExecStart = "${config.systemd.package}/lib/systemd/systemd-sysctl";
};
};
# Enable hardlink and symlink restrictions. See
# https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=800179c9b8a1e796e441674776d11cd4c05d61d7
# for details.
boot.kernel.sysctl."fs.protected_hardlinks" = true;
boot.kernel.sysctl."fs.protected_symlinks" = true;
# Hide kernel pointers (e.g. in /proc/modules) for unprivileged
# users as these make it easier to exploit kernel vulnerabilities.
#
# Removed under grsecurity.
boot.kernel.sysctl."kernel.kptr_restrict" =
if config.security.grsecurity.enable then null else 1;
};
}