265 lines
8.2 KiB
Nix
265 lines
8.2 KiB
Nix
{ config, lib, pkgs, ... }:
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with lib;
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let
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cfg = config.security.sudo;
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inherit (pkgs) sudo;
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toUserString = user: if (isInt user) then "#${toString user}" else "${user}";
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toGroupString = group: if (isInt group) then "%#${toString group}" else "%${group}";
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toCommandOptionsString = options:
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"${concatStringsSep ":" options}${optionalString (length options != 0) ":"} ";
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toCommandsString = commands:
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concatStringsSep ", " (
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map (command:
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if (isString command) then
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command
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else
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"${toCommandOptionsString command.options}${command.command}"
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) commands
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);
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in
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{
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###### interface
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options = {
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security.sudo.enable = mkOption {
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type = types.bool;
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default = true;
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description =
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''
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Whether to enable the <command>sudo</command> command, which
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allows non-root users to execute commands as root.
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'';
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};
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security.sudo.package = mkOption {
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type = types.package;
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default = pkgs.sudo;
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defaultText = literalExpression "pkgs.sudo";
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description = ''
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Which package to use for `sudo`.
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'';
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};
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security.sudo.wheelNeedsPassword = mkOption {
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type = types.bool;
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default = true;
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description =
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''
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Whether users of the <code>wheel</code> group must
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provide a password to run commands as super user via <command>sudo</command>.
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'';
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};
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security.sudo.execWheelOnly = mkOption {
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type = types.bool;
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default = false;
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description = ''
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Only allow members of the <code>wheel</code> group to execute sudo by
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setting the executable's permissions accordingly.
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This prevents users that are not members of <code>wheel</code> from
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exploiting vulnerabilities in sudo such as CVE-2021-3156.
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'';
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};
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security.sudo.configFile = mkOption {
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type = types.lines;
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# Note: if syntax errors are detected in this file, the NixOS
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# configuration will fail to build.
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description =
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''
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This string contains the contents of the
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<filename>sudoers</filename> file.
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'';
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};
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security.sudo.extraRules = mkOption {
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description = ''
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Define specific rules to be in the <filename>sudoers</filename> file.
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More specific rules should come after more general ones in order to
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yield the expected behavior. You can use mkBefore/mkAfter to ensure
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this is the case when configuration options are merged.
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'';
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default = [];
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example = literalExpression ''
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[
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# Allow execution of any command by all users in group sudo,
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# requiring a password.
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{ groups = [ "sudo" ]; commands = [ "ALL" ]; }
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# Allow execution of "/home/root/secret.sh" by user `backup`, `database`
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# and the group with GID `1006` without a password.
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{ users = [ "backup" "database" ]; groups = [ 1006 ];
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commands = [ { command = "/home/root/secret.sh"; options = [ "SETENV" "NOPASSWD" ]; } ]; }
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# Allow all users of group `bar` to run two executables as user `foo`
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# with arguments being pre-set.
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{ groups = [ "bar" ]; runAs = "foo";
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commands =
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[ "/home/baz/cmd1.sh hello-sudo"
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{ command = '''/home/baz/cmd2.sh ""'''; options = [ "SETENV" ]; } ]; }
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]
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'';
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type = with types; listOf (submodule {
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options = {
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users = mkOption {
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type = with types; listOf (either str int);
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description = ''
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The usernames / UIDs this rule should apply for.
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'';
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default = [];
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};
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groups = mkOption {
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type = with types; listOf (either str int);
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description = ''
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The groups / GIDs this rule should apply for.
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'';
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default = [];
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};
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host = mkOption {
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type = types.str;
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default = "ALL";
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description = ''
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For what host this rule should apply.
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'';
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};
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runAs = mkOption {
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type = with types; str;
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default = "ALL:ALL";
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description = ''
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Under which user/group the specified command is allowed to run.
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A user can be specified using just the username: <code>"foo"</code>.
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It is also possible to specify a user/group combination using <code>"foo:bar"</code>
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or to only allow running as a specific group with <code>":bar"</code>.
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'';
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};
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commands = mkOption {
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description = ''
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The commands for which the rule should apply.
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'';
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type = with types; listOf (either str (submodule {
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options = {
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command = mkOption {
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type = with types; str;
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description = ''
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A command being either just a path to a binary to allow any arguments,
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the full command with arguments pre-set or with <code>""</code> used as the argument,
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not allowing arguments to the command at all.
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'';
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};
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options = mkOption {
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type = with types; listOf (enum [ "NOPASSWD" "PASSWD" "NOEXEC" "EXEC" "SETENV" "NOSETENV" "LOG_INPUT" "NOLOG_INPUT" "LOG_OUTPUT" "NOLOG_OUTPUT" ]);
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description = ''
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Options for running the command. Refer to the <a href="https://www.sudo.ws/man/1.7.10/sudoers.man.html">sudo manual</a>.
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'';
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default = [];
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};
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};
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}));
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};
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};
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});
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};
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security.sudo.extraConfig = mkOption {
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type = types.lines;
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default = "";
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description = ''
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Extra configuration text appended to <filename>sudoers</filename>.
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'';
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};
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};
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###### implementation
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config = mkIf cfg.enable {
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# We `mkOrder 600` so that the default rule shows up first, but there is
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# still enough room for a user to `mkBefore` it.
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security.sudo.extraRules = mkOrder 600 [
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{ groups = [ "wheel" ];
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commands = [ { command = "ALL"; options = (if cfg.wheelNeedsPassword then [ "SETENV" ] else [ "NOPASSWD" "SETENV" ]); } ];
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}
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];
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security.sudo.configFile =
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''
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# Don't edit this file. Set the NixOS options ‘security.sudo.configFile’
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# or ‘security.sudo.extraRules’ instead.
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# Keep SSH_AUTH_SOCK so that pam_ssh_agent_auth.so can do its magic.
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Defaults env_keep+=SSH_AUTH_SOCK
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# "root" is allowed to do anything.
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root ALL=(ALL:ALL) SETENV: ALL
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# extraRules
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${concatStringsSep "\n" (
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lists.flatten (
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map (
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rule: if (length rule.commands != 0) then [
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(map (user: "${toUserString user} ${rule.host}=(${rule.runAs}) ${toCommandsString rule.commands}") rule.users)
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(map (group: "${toGroupString group} ${rule.host}=(${rule.runAs}) ${toCommandsString rule.commands}") rule.groups)
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] else []
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) cfg.extraRules
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)
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)}
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${cfg.extraConfig}
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'';
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security.wrappers = let
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owner = "root";
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group = if cfg.execWheelOnly then "wheel" else "root";
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setuid = true;
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permissions = if cfg.execWheelOnly then "u+rx,g+x" else "u+rx,g+x,o+x";
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in {
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sudo = {
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source = "${cfg.package.out}/bin/sudo";
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inherit owner group setuid permissions;
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};
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sudoedit = {
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source = "${cfg.package.out}/bin/sudoedit";
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inherit owner group setuid permissions;
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};
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};
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environment.systemPackages = [ sudo ];
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security.pam.services.sudo = { sshAgentAuth = true; usshAuth = true; };
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environment.etc.sudoers =
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{ source =
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pkgs.runCommand "sudoers"
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{
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src = pkgs.writeText "sudoers-in" cfg.configFile;
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preferLocalBuild = true;
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}
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# Make sure that the sudoers file is syntactically valid.
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# (currently disabled - NIXOS-66)
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"${pkgs.buildPackages.sudo}/sbin/visudo -f $src -c && cp $src $out";
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mode = "0440";
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};
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};
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}
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