2e751c0772
the conversion procedure is simple: - find all things that look like options, ie calls to either `mkOption` or `lib.mkOption` that take an attrset. remember the attrset as the option - for all options, find a `description` attribute who's value is not a call to `mdDoc` or `lib.mdDoc` - textually convert the entire value of the attribute to MD with a few simple regexes (the set from mdize-module.sh) - if the change produced a change in the manual output, discard - if the change kept the manual unchanged, add some text to the description to make sure we've actually found an option. if the manual changes this time, keep the converted description this procedure converts 80% of nixos options to markdown. around 2000 options remain to be inspected, but most of those fail the "does not change the manual output check": currently the MD conversion process does not faithfully convert docbook tags like <code> and <package>, so any option using such tags will not be converted at all.
124 lines
3.7 KiB
Nix
124 lines
3.7 KiB
Nix
{ config, lib, pkgs, ... }:
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with lib;
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let
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cfg = config.security.audit;
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enabled = cfg.enable == "lock" || cfg.enable;
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failureModes = {
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silent = 0;
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printk = 1;
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panic = 2;
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};
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disableScript = pkgs.writeScript "audit-disable" ''
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#!${pkgs.runtimeShell} -eu
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# Explicitly disable everything, as otherwise journald might start it.
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auditctl -D
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auditctl -e 0 -a task,never
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'';
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# TODO: it seems like people like their rules to be somewhat secret, yet they will not be if
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# put in the store like this. At the same time, it doesn't feel like a huge deal and working
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# around that is a pain so I'm leaving it like this for now.
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startScript = pkgs.writeScript "audit-start" ''
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#!${pkgs.runtimeShell} -eu
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# Clear out any rules we may start with
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auditctl -D
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# Put the rules in a temporary file owned and only readable by root
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rulesfile="$(mktemp)"
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${concatMapStrings (x: "echo '${x}' >> $rulesfile\n") cfg.rules}
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# Apply the requested rules
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auditctl -R "$rulesfile"
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# Enable and configure auditing
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auditctl \
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-e ${if cfg.enable == "lock" then "2" else "1"} \
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-b ${toString cfg.backlogLimit} \
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-f ${toString failureModes.${cfg.failureMode}} \
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-r ${toString cfg.rateLimit}
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'';
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stopScript = pkgs.writeScript "audit-stop" ''
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#!${pkgs.runtimeShell} -eu
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# Clear the rules
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auditctl -D
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# Disable auditing
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auditctl -e 0
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'';
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in {
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options = {
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security.audit = {
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enable = mkOption {
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type = types.enum [ false true "lock" ];
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default = false;
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description = lib.mdDoc ''
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Whether to enable the Linux audit system. The special `lock' value can be used to
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enable auditing and prevent disabling it until a restart. Be careful about locking
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this, as it will prevent you from changing your audit configuration until you
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restart. If possible, test your configuration using build-vm beforehand.
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'';
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};
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failureMode = mkOption {
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type = types.enum [ "silent" "printk" "panic" ];
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default = "printk";
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description = lib.mdDoc "How to handle critical errors in the auditing system";
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};
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backlogLimit = mkOption {
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type = types.int;
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default = 64; # Apparently the kernel default
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description = lib.mdDoc ''
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The maximum number of outstanding audit buffers allowed; exceeding this is
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considered a failure and handled in a manner specified by failureMode.
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'';
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};
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rateLimit = mkOption {
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type = types.int;
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default = 0;
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description = lib.mdDoc ''
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The maximum messages per second permitted before triggering a failure as
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specified by failureMode. Setting it to zero disables the limit.
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'';
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};
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rules = mkOption {
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type = types.listOf types.str; # (types.either types.str (types.submodule rule));
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default = [];
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example = [ "-a exit,always -F arch=b64 -S execve" ];
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description = lib.mdDoc ''
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The ordered audit rules, with each string appearing as one line of the audit.rules file.
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'';
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};
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};
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};
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config = {
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systemd.services.audit = {
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description = "Kernel Auditing";
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wantedBy = [ "basic.target" ];
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unitConfig = {
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ConditionVirtualization = "!container";
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ConditionSecurity = [ "audit" ];
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};
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path = [ pkgs.audit ];
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serviceConfig = {
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Type = "oneshot";
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RemainAfterExit = true;
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ExecStart = "@${if enabled then startScript else disableScript} audit-start";
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ExecStop = "@${stopScript} audit-stop";
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};
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};
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};
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}
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