262 lines
9.7 KiB
Nix
262 lines
9.7 KiB
Nix
# This module provides configuration for the PAM (Pluggable
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# Authentication Modules) system.
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{config, pkgs, ...}:
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with pkgs.lib;
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let
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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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otherService = pkgs.writeText "other.pam"
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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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# Create a limits.conf(5) file.
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makeLimitsConf = limits:
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pkgs.writeText "limits.conf"
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(concatStringsSep "\n"
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(map ({ domain, type, item, value }:
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concatStringsSep " " [ domain type item value ])
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limits));
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motd = pkgs.writeText "motd" config.users.motd;
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makePAMService =
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{ name
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, # If set, root doesn't need to authenticate (e.g. for the "chsh"
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# service).
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rootOK ? false
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, # If set, user listed in /etc/pamusb.conf are able to log in with
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# the associated usb key.
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usbAuth ? config.security.pam.usb.enable
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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 ~/.ssh/authorized_keys.
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# This is useful for "sudo" on password-less remote systems.
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sshAgentAuth ? false
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, # If set, the service will register a new session with systemd's
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# login manager. If the service is running locally, this will
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# give the user ownership of audio devices etc.
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startSession ? false
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, # Whether to forward XAuth keys between users. Mostly useful
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# for "su".
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forwardXAuth ? false
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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 /etc/passwd or
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# /etc/group). This does not enable logging into disabled
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# accounts (i.e., that have the password field set to `!').
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# Note that regardless of what the pam_unix documentation says,
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# accounts with hashed empty passwords are always allowed to log
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# in.
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allowNullPassword ? false
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, # The limits, as per limits.conf(5).
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limits ? config.security.pam.loginLimits
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, # Whether to show the message of the day.
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showMotd ? false
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}:
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{ source = pkgs.writeText "${name}.pam"
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# !!! TODO: move the LDAP stuff to the LDAP module, and the
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# Samba stuff to the Samba module. This requires that the PAM
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# module provides the right hooks.
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''
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# Account management.
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account sufficient pam_unix.so
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${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 rootOK
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"auth sufficient pam_rootok.so"}
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${optionalString (config.security.pam.enableSSHAgentAuth && 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 usbAuth
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"auth sufficient ${pkgs.pam_usb}/lib/security/pam_usb.so"}
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auth sufficient pam_unix.so ${optionalString allowNullPassword "nullok"} likeauth
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${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 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 startSession
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"session optional ${pkgs.systemd}/lib/security/pam_systemd.so"}
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${optionalString forwardXAuth
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"session optional pam_xauth.so xauthpath=${pkgs.xorg.xauth}/bin/xauth systemuser=99"}
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${optionalString (limits != [])
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"session required ${pkgs.pam}/lib/security/pam_limits.so conf=${makeLimitsConf limits}"}
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${optionalString (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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target = "pam.d/${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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example = [
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{ name = "chsh"; rootOK = true; }
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{ name = "login"; startSession = true; allowNullPassword = true;
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limits = [
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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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];
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}
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];
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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 element of this list is an attribute set describing a
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service. The attribute <varname>name</varname> specifies
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the name of the service. The attribute
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<varname>rootOK</varname> specifies whether the root user is
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allowed to use this service without authentication. The
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attribute <varname>startSession</varname> specifies whether
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systemd's PAM connector module should be used to start a new
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session; for local sessions, this will give the user
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ownership of devices such as audio and CD-ROM drives. The
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attribute <varname>forwardXAuth</varname> specifies whether
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X authentication keys should be passed from the calling user
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to the target user (e.g. for <command>su</command>).
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The attribute <varname>limits</varname> defines resource limits
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that should apply to users or groups for the service. Each item in
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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> attribute.
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The syntax and semantics of these attributes must be that described
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in the limits.conf(5) man page.
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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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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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++ optional config.krb5.enable [pam_krb5 pam_ccreds];
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environment.etc =
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map makePAMService config.security.pam.services
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++ singleton
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{ source = otherService;
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target = "pam.d/other";
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};
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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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# Most of these should be moved to specific modules.
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[ { name = "cups"; }
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{ name = "ejabberd"; }
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{ name = "ftp"; }
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{ name = "i3lock"; }
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{ name = "lshd"; }
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{ name = "samba"; }
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{ name = "screen"; }
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{ name = "vlock"; }
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{ name = "xlock"; }
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{ name = "xscreensaver"; }
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];
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};
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}
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