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.
354 lines
12 KiB
Nix
354 lines
12 KiB
Nix
# This module provides configuration for the PAM (Pluggable
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# Authentication Modules) system.
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{ config, lib, pkgs, ... }:
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with lib;
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let
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pamOpts = args: {
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options = {
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name = mkOption {
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example = "sshd";
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type = types.str;
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description = "Name of the PAM service.";
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};
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unixAuth = mkOption {
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default = true;
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type = types.bool;
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description = ''
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Whether users can log in with passwords defined in
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<filename>/etc/shadow</filename>.
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'';
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};
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rootOK = mkOption {
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default = false;
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type = types.bool;
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description = ''
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If set, root doesn't need to authenticate (e.g. for the
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<command>useradd</command> service).
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'';
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};
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usbAuth = mkOption {
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default = config.security.pam.usb.enable;
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type = types.bool;
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description = ''
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If set, users listed in
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<filename>/etc/pamusb.conf</filename> are able to log in
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with the associated USB key.
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'';
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};
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otpwAuth = mkOption {
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default = config.security.pam.enableOTPW;
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type = types.bool;
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description = ''
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If set, the OTPW system will be used (if
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<filename>~/.otpw</filename> exists).
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'';
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};
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sshAgentAuth = mkOption {
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default = false;
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type = types.bool;
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description = ''
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If set, the calling user's SSH agent is used to authenticate
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against the keys in the calling user's
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<filename>~/.ssh/authorized_keys</filename>. This is useful
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for <command>sudo</command> on password-less remote systems.
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'';
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};
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startSession = mkOption {
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default = false;
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type = types.bool;
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description = ''
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If set, the service will register a new session with
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systemd's login manager. For local sessions, this will give
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the user access to audio devices, CD-ROM drives. In the
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default PolicyKit configuration, it also allows the user to
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reboot the system.
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'';
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};
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setLoginUid = mkOption {
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type = types.bool;
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description = ''
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Set the login uid of the process
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(<filename>/proc/self/loginuid</filename>) for auditing
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purposes. The login uid is only set by ‘entry points’ like
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<command>login</command> and <command>sshd</command>, not by
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commands like <command>sudo</command>.
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'';
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};
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forwardXAuth = mkOption {
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default = false;
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type = types.bool;
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description = ''
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Whether X authentication keys should be passed from the
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calling user to the target user (e.g. for
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<command>su</command>)
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'';
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};
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allowNullPassword = mkOption {
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default = false;
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type = types.bool;
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description = ''
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Whether to allow logging into accounts that have no password
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set (i.e., have an empty password field in
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<filename>/etc/passwd</filename> or
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<filename>/etc/group</filename>). This does not enable
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logging into disabled accounts (i.e., that have the password
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field set to <literal>!</literal>). Note that regardless of
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what the pam_unix documentation says, accounts with hashed
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empty passwords are always allowed to log in.
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'';
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};
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limits = mkOption {
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description = ''
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Attribute set describing resource limits. Defaults to the
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value of <option>security.pam.loginLimits</option>.
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'';
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};
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showMotd = mkOption {
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default = false;
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type = types.bool;
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description = "Whether to show the message of the day.";
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};
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updateWtmp = mkOption {
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default = false;
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type = types.bool;
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description = "Whether to update <filename>/var/log/wtmp</filename>.";
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};
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text = mkOption {
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type = types.nullOr types.lines;
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description = "Contents of the PAM service file.";
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};
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};
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config = let cfg = args.config; in {
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name = mkDefault args.name;
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setLoginUid = mkDefault cfg.startSession;
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limits = mkDefault config.security.pam.loginLimits;
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# !!! TODO: move the LDAP stuff to the LDAP module, and the
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# Samba stuff to the Samba module. This requires that the PAM
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# module provides the right hooks.
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text = mkDefault
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''
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# Account management.
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account sufficient pam_unix.so
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${optionalString config.users.ldap.enable
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"account sufficient ${pam_ldap}/lib/security/pam_ldap.so"}
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${optionalString config.krb5.enable
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"account sufficient ${pam_krb5}/lib/security/pam_krb5.so"}
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# Authentication management.
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${optionalString cfg.rootOK
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"auth sufficient pam_rootok.so"}
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${optionalString (config.security.pam.enableSSHAgentAuth && cfg.sshAgentAuth)
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"auth sufficient ${pkgs.pam_ssh_agent_auth}/libexec/pam_ssh_agent_auth.so file=~/.ssh/authorized_keys:~/.ssh/authorized_keys2:/etc/ssh/authorized_keys.d/%u"}
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${optionalString cfg.usbAuth
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"auth sufficient ${pkgs.pam_usb}/lib/security/pam_usb.so"}
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${optionalString cfg.unixAuth
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"auth sufficient pam_unix.so ${optionalString cfg.allowNullPassword "nullok"} likeauth"}
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${optionalString cfg.otpwAuth
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"auth sufficient ${pkgs.otpw}/lib/security/pam_otpw.so"}
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${optionalString config.users.ldap.enable
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"auth sufficient ${pam_ldap}/lib/security/pam_ldap.so use_first_pass"}
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${optionalString config.krb5.enable ''
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auth [default=ignore success=1 service_err=reset] ${pam_krb5}/lib/security/pam_krb5.so use_first_pass
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auth [default=die success=done] ${pam_ccreds}/lib/security/pam_ccreds.so action=validate use_first_pass
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auth sufficient ${pam_ccreds}/lib/security/pam_ccreds.so action=store use_first_pass
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''}
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auth required pam_deny.so
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# Password management.
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password requisite pam_unix.so nullok sha512
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${optionalString config.users.ldap.enable
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"password sufficient ${pam_ldap}/lib/security/pam_ldap.so"}
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${optionalString config.krb5.enable
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"password sufficient ${pam_krb5}/lib/security/pam_krb5.so use_first_pass"}
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${optionalString config.services.samba.syncPasswordsByPam
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"password optional ${pkgs.samba}/lib/security/pam_smbpass.so nullok use_authtok try_first_pass"}
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# Session management.
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session required pam_unix.so
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${optionalString cfg.updateWtmp
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"session required ${pkgs.pam}/lib/security/pam_lastlog.so silent"}
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${optionalString config.users.ldap.enable
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"session optional ${pam_ldap}/lib/security/pam_ldap.so"}
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${optionalString config.krb5.enable
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"session optional ${pam_krb5}/lib/security/pam_krb5.so"}
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${optionalString cfg.otpwAuth
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"session optional ${pkgs.otpw}/lib/security/pam_otpw.so"}
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${optionalString cfg.startSession
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"session optional ${pkgs.systemd}/lib/security/pam_systemd.so"}
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${optionalString cfg.setLoginUid
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"session required pam_loginuid.so"}
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${optionalString cfg.forwardXAuth
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"session optional pam_xauth.so xauthpath=${pkgs.xorg.xauth}/bin/xauth systemuser=99"}
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${optionalString (cfg.limits != [])
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"session required ${pkgs.pam}/lib/security/pam_limits.so conf=${makeLimitsConf cfg.limits}"}
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${optionalString (cfg.showMotd && config.users.motd != null)
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"session optional ${pkgs.pam}/lib/security/pam_motd.so motd=${motd}"}
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'';
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};
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};
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inherit (pkgs) pam_krb5 pam_ccreds;
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pam_ldap = if config.users.ldap.daemon.enable then pkgs.nss_pam_ldapd else pkgs.pam_ldap;
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# Create a limits.conf(5) file.
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makeLimitsConf = limits:
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pkgs.writeText "limits.conf"
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(concatMapStrings ({ domain, type, item, value }:
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"${domain} ${type} ${item} ${toString value}\n")
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limits);
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motd = pkgs.writeText "motd" config.users.motd;
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makePAMService = pamService:
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{ source = pkgs.writeText "${pamService.name}.pam" pamService.text;
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target = "pam.d/${pamService.name}";
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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.pam.loginLimits = mkOption {
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default = [];
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example =
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[ { domain = "ftp";
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type = "hard";
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item = "nproc";
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value = "0";
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}
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{ domain = "@student";
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type = "-";
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item = "maxlogins";
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value = "4";
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}
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];
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description =
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'' Define resource limits that should apply to users or groups.
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Each item in the list should be an attribute set with a
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<varname>domain</varname>, <varname>type</varname>,
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<varname>item</varname>, and <varname>value</varname>
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attribute. The syntax and semantics of these attributes
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must be that described in the limits.conf(5) man page.
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'';
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};
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security.pam.services = mkOption {
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default = [];
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type = types.loaOf types.optionSet;
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options = [ pamOpts ];
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description =
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''
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This option defines the PAM services. A service typically
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corresponds to a program that uses PAM,
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e.g. <command>login</command> or <command>passwd</command>.
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Each attribute of this set defines a PAM service, with the attribute name
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defining the name of the service.
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'';
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};
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security.pam.enableSSHAgentAuth = mkOption {
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default = false;
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description =
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''
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Enable sudo logins if the user's SSH agent provides a key
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present in <filename>~/.ssh/authorized_keys</filename>.
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This allows machines to exclusively use SSH keys instead of
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passwords.
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'';
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};
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security.pam.enableOTPW = mkOption {
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default = false;
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description = ''
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Enable the OTPW (one-time password) PAM module.
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'';
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};
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users.motd = mkOption {
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default = null;
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example = "Today is Sweetmorn, the 4th day of The Aftermath in the YOLD 3178.";
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type = types.nullOr types.string;
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description = "Message of the day shown to users when they log in.";
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};
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};
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###### implementation
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config = {
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environment.systemPackages =
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# Include the PAM modules in the system path mostly for the manpages.
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[ pkgs.pam ]
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++ optional config.users.ldap.enable pam_ldap
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++ optionals config.krb5.enable [pam_krb5 pam_ccreds]
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++ optionals config.security.pam.enableOTPW [ pkgs.otpw ];
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environment.etc =
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mapAttrsToList (n: v: makePAMService v) config.security.pam.services;
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security.setuidOwners = [ {
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program = "unix_chkpwd";
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source = "${pkgs.pam}/sbin/unix_chkpwd.orig";
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owner = "root";
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setuid = true;
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} ];
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security.pam.services =
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{ other.text =
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''
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auth required pam_warn.so
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auth required pam_deny.so
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account required pam_warn.so
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account required pam_deny.so
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password required pam_warn.so
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password required pam_deny.so
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session required pam_warn.so
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session required pam_deny.so
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'';
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# Most of these should be moved to specific modules.
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cups = {};
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ftp = {};
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i3lock = {};
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screen = {};
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vlock = {};
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xlock = {};
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xscreensaver = {};
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};
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};
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}
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