d5daa8ae6f
"Can either by" should be "Can either be". There are three occurrences of this mistake, all in descriptions of configuration options.
315 lines
11 KiB
Nix
315 lines
11 KiB
Nix
{ config, lib, pkgs, ... }:
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with lib;
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let
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cfg = config.security.grsecurity;
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customGrsecPkg =
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(import ../../../pkgs/build-support/grsecurity {
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grsecOptions = cfg;
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inherit pkgs lib;
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}).grsecPackage;
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in
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{
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options = {
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security.grsecurity = {
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enable = mkOption {
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type = types.bool;
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default = false;
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description = ''
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Enable grsecurity support. This enables advanced exploit
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hardening for the Linux kernel, and adds support for
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administrative Role-Based Acess Control (RBAC) via
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<literal>gradm</literal>. It also includes traditional
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utilities for PaX.
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'';
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};
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stable = mkOption {
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type = types.bool;
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default = false;
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description = ''
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Enable the stable grsecurity patch, based on Linux 3.2.
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'';
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};
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testing = mkOption {
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type = types.bool;
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default = false;
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description = ''
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Enable the testing grsecurity patch, based on Linux 3.13.
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'';
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};
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config = {
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mode = mkOption {
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type = types.str;
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default = "auto";
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example = "custom";
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description = ''
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grsecurity configuration mode. This specifies whether
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grsecurity is auto-configured or otherwise completely
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manually configured. Can either be
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<literal>custom</literal> or <literal>auto</literal>.
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<literal>auto</literal> is recommended.
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'';
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};
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priority = mkOption {
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type = types.str;
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default = "security";
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example = "performance";
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description = ''
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grsecurity configuration priority. This specifies whether
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the kernel configuration should emphasize speed or
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security. Can either be <literal>security</literal> or
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<literal>performance</literal>.
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'';
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};
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system = mkOption {
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type = types.str;
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default = "";
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example = "desktop";
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description = ''
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grsecurity system configuration. This specifies whether
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the kernel configuration should be suitable for a Desktop
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or a Server. Can either be <literal>server</literal> or
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<literal>desktop</literal>.
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'';
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};
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virtualisationConfig = mkOption {
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type = types.str;
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default = "none";
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example = "host";
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description = ''
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grsecurity virtualisation configuration. This specifies
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the virtualisation role of the machine - that is, whether
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it will be a virtual machine guest, a virtual machine
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host, or neither. Can be one of <literal>none</literal>,
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<literal>host</literal>, or <literal>guest</literal>.
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'';
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};
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hardwareVirtualisation = mkOption {
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type = types.nullOr types.bool;
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default = null;
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example = true;
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description = ''
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grsecurity hardware virtualisation configuration. Set to
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<literal>true</literal> if your machine supports hardware
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accelerated virtualisation.
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'';
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};
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virtualisationSoftware = mkOption {
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type = types.str;
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default = "";
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example = "kvm";
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description = ''
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grsecurity virtualisation software. Set this to the
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specified virtual machine technology if the machine is
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running as a guest, or a host.
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Can be one of <literal>kvm</literal>,
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<literal>xen</literal>, <literal>vmware</literal> or
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<literal>virtualbox</literal>.
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'';
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};
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sysctl = mkOption {
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type = types.bool;
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default = false;
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description = ''
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If true, then set <literal>GRKERN_SYSCTL y</literal>. If
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enabled then grsecurity can be controlled using sysctl
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(and turned off). You are advised to *never* enable this,
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but if you do, make sure to always set the sysctl
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<literal>kernel.grsecurity.grsec_lock</literal> to
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non-zero as soon as all sysctl options are set. *THIS IS
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EXTREMELY IMPORTANT*!
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If disabled, this also turns off the
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<literal>systemd-sysctl</literal> service.
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'';
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};
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denyChrootChmod = mkOption {
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type = types.bool;
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default = false;
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description = ''
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If true, then set <literal>GRKERN_CHROOT_CHMOD
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y</literal>. If enabled, this denies processes inside a
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chroot from setting the suid or sgid bits using
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<literal>chmod</literal> or <literal>fchmod</literal>.
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By default this protection is disabled - it makes it
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impossible to use Nix to build software on your system,
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which is what most users want.
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If you are using NixOps to deploy your software to a
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remote machine, you're encouraged to enable this as you
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won't need to compile code.
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'';
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};
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restrictProc = mkOption {
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type = types.bool;
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default = false;
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description = ''
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If true, then set <literal>GRKERN_PROC_USER
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y</literal>. This restricts non-root users to only viewing
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their own processes and restricts network-related
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information, kernel symbols, and module information.
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'';
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};
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restrictProcWithGroup = mkOption {
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type = types.bool;
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default = true;
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description = ''
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If true, then set <literal>GRKERN_PROC_USERGROUP
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y</literal>. This is similar to
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<literal>restrictProc</literal> except it allows a special
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group (specified by <literal>unrestrictProcGid</literal>)
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to still access otherwise classified information in
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<literal>/proc</literal>.
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'';
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};
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unrestrictProcGid = mkOption {
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type = types.int;
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default = config.ids.gids.grsecurity;
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description = ''
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If set, specifies a GID which is exempt from
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<literal>/proc</literal> restrictions (set by
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<literal>GRKERN_PROC_USERGROUP</literal>). By default,
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this is set to the GID for <literal>grsecurity</literal>,
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a predefined NixOS group, which the
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<literal>root</literal> account is a member of. You may
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conveniently add other users to this group if you need
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access to <literal>/proc</literal>
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'';
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};
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disableRBAC = mkOption {
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type = types.bool;
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default = false;
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description = ''
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If true, then set <literal>GRKERN_NO_RBAC
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y</literal>. This disables the
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<literal>/dev/grsec</literal> device, which in turn
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disables the RBAC system (and <literal>gradm</literal>).
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'';
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};
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verboseVersion = mkOption {
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type = types.bool;
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default = false;
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description = "Use verbose version in kernel localversion.";
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};
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kernelExtraConfig = mkOption {
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type = types.str;
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default = "";
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description = "Extra kernel configuration parameters.";
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};
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};
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};
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};
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config = mkIf cfg.enable {
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assertions =
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[ { assertion = cfg.stable || cfg.testing;
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message = ''
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If grsecurity is enabled, you must select either the
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stable patch (with kernel 3.2), or the testing patch (with
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kernel 3.13) to continue.
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'';
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}
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{ assertion = (cfg.stable -> !cfg.testing) || (cfg.testing -> !cfg.stable);
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message = ''
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You must select either the stable or testing patch, not
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both.
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'';
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}
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{ assertion = (cfg.config.restrictProc -> !cfg.config.restrictProcWithGroup) ||
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(cfg.config.restrictProcWithGroup -> !cfg.config.restrictProc);
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message = "You cannot enable both restrictProc and restrictProcWithGroup";
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}
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{ assertion = config.boot.kernelPackages.kernel.features ? grsecurity
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&& config.boot.kernelPackages.kernel.features.grsecurity;
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message = "grsecurity enabled, but kernel doesn't have grsec support";
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}
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{ assertion = elem cfg.config.mode [ "auto" "custom" ];
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message = "grsecurity mode must either be 'auto' or 'custom'.";
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}
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{ assertion = cfg.config.mode == "auto" -> elem cfg.config.system [ "desktop" "server" ];
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message = "when using auto grsec mode, system must be either 'desktop' or 'server'";
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}
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{ assertion = cfg.config.mode == "auto" -> elem cfg.config.priority [ "performance" "security" ];
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message = "when using auto grsec mode, priority must be 'performance' or 'security'.";
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}
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{ assertion = cfg.config.mode == "auto" -> elem cfg.config.virtualisationConfig [ "host" "guest" "none" ];
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message = "when using auto grsec mode, 'virt' must be 'host', 'guest' or 'none'.";
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}
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{ assertion = (cfg.config.mode == "auto" && (elem cfg.config.virtualisationConfig [ "host" "guest" ])) ->
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cfg.config.hardwareVirtualisation != null;
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message = "when using auto grsec mode with virtualisation, you must specify if your hardware has virtualisation extensions";
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}
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{ assertion = (cfg.config.mode == "auto" && (elem cfg.config.virtualisationConfig [ "host" "guest" ])) ->
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elem cfg.config.virtualisationSoftware [ "kvm" "xen" "virtualbox" "vmware" ];
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message = "virtualisation software must be 'kvm', 'xen', 'vmware' or 'virtualbox'";
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}
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];
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systemd.services.grsec-lock = mkIf cfg.config.sysctl {
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description = "grsecurity sysctl-lock Service";
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requires = [ "sysctl.service" ];
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wantedBy = [ "multi-user.target" ];
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serviceConfig.Type = "oneshot";
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serviceConfig.RemainAfterExit = "yes";
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script = ''
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locked=`cat /proc/sys/kernel/grsecurity/grsec_lock`
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if [ "$locked" == "0" ]; then
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echo 1 > /proc/sys/kernel/grsecurity/grsec_lock
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echo grsecurity sysctl lock - enabled
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else
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echo grsecurity sysctl lock already enabled - doing nothing
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fi
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'';
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};
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# systemd.services.grsec-learn = {
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# description = "grsecurity learning Service";
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# wantedBy = [ "local-fs.target" ];
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# serviceConfig = {
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# Type = "oneshot";
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# RemainAfterExit = "yes";
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# ExecStart = "${pkgs.gradm}/sbin/gradm -VFL /etc/grsec/learning.logs";
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# ExecStop = "${pkgs.gradm}/sbin/gradm -D";
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# };
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# };
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system.activationScripts.grsec =
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''
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mkdir -p /etc/grsec
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if [ ! -f /etc/grsec/learn_config ]; then
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cp ${pkgs.gradm}/etc/grsec/learn_config /etc/grsec
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fi
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if [ ! -f /etc/grsec/policy ]; then
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cp ${pkgs.gradm}/etc/grsec/policy /etc/grsec
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fi
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chmod -R 0600 /etc/grsec
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'';
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# Enable AppArmor, gradm udev rules, and utilities
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security.apparmor.enable = true;
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boot.kernelPackages = customGrsecPkg;
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services.udev.packages = [ pkgs.gradm ];
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environment.systemPackages = [ pkgs.gradm pkgs.paxctl pkgs.pax-utils ];
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};
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}
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