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nixpkgs/modules/security/pam.nix
Eelco Dolstra 490ce3a230 PAM: Rename ownDevices to startSession
Logind sessions are more generally useful than for device ownership.
For instances, ssh logins can be put in their own session (and thus
their own cgroup).
2012-08-17 13:48:22 -04:00

247 lines
9 KiB
Nix

# This module provides configuration for the PAM (Pluggable
# Authentication Modules) system.
{config, pkgs, ...}:
with pkgs.lib;
let
inherit (pkgs) pam_ldap pam_krb5 pam_ccreds;
otherService = pkgs.writeText "other.pam"
''
auth required pam_warn.so
auth required pam_deny.so
account required pam_warn.so
account required pam_deny.so
password required pam_warn.so
password required pam_deny.so
session required pam_warn.so
session required pam_deny.so
'';
# Create a limits.conf(5) file.
makeLimitsConf = limits:
pkgs.writeText "limits.conf"
(concatStringsSep "\n"
(map ({ domain, type, item, value }:
concatStringsSep " " [ domain type item value ])
limits));
makePAMService =
{ name
, # If set, root doesn't need to authenticate (e.g. for the "chsh"
# service).
rootOK ? false
, # If set, user listed in /etc/pamusb.conf are able to log in with
# the associated usb key.
usbAuth ? config.security.pam.usb.enable
, # If set, the calling user's SSH agent is used to authenticate
# against the keys in the calling user's ~/.ssh/authorized_keys.
# This is useful for "sudo" on password-less remote systems.
sshAgentAuth ? false
, # If set, the service will register a new session with systemd's
# login manager. If the service is running locally, this will
# give the user ownership of audio devices etc.
startSession ? false
, # Whether to forward XAuth keys between users. Mostly useful
# for "su".
forwardXAuth ? false
, # Whether to allow logging into accounts that have no password
# set (i.e., have an empty password field in /etc/passwd or
# /etc/group). This does not enable logging into disabled
# accounts (i.e., that have the password field set to `!').
# Note that regardless of what the pam_unix documentation says,
# accounts with hashed empty passwords are always allowed to log
# in.
allowNullPassword ? false
, # The limits, as per limits.conf(5).
limits ? config.security.pam.loginLimits
}:
{ source = pkgs.writeText "${name}.pam"
# !!! TODO: move the LDAP stuff to the LDAP module, and the
# Samba stuff to the Samba module. This requires that the PAM
# module provides the right hooks.
''
# Account management.
account sufficient pam_unix.so
${optionalString config.users.ldap.enable
"account sufficient ${pam_ldap}/lib/security/pam_ldap.so"}
${optionalString config.krb5.enable
"account sufficient ${pam_krb5}/lib/security/pam_krb5.so"}
# Authentication management.
${optionalString rootOK
"auth sufficient pam_rootok.so"}
${optionalString (config.security.pam.enableSSHAgentAuth && sshAgentAuth)
"auth sufficient ${pkgs.pam_ssh_agent_auth}/libexec/pam_ssh_agent_auth.so file=~/.ssh/authorized_keys"}
${optionalString usbAuth
"auth sufficient ${pkgs.pam_usb}/lib/security/pam_usb.so"}
auth sufficient pam_unix.so ${optionalString allowNullPassword "nullok"} likeauth
${optionalString config.users.ldap.enable
"auth sufficient ${pam_ldap}/lib/security/pam_ldap.so use_first_pass"}
${optionalString config.krb5.enable ''
auth [default=ignore success=1 service_err=reset] ${pam_krb5}/lib/security/pam_krb5.so use_first_pass
auth [default=die success=done] ${pam_ccreds}/lib/security/pam_ccreds.so action=validate use_first_pass
auth sufficient ${pam_ccreds}/lib/security/pam_ccreds.so action=store use_first_pass
''}
auth required pam_deny.so
# Password management.
password requisite pam_unix.so nullok sha512
${optionalString config.users.ldap.enable
"password sufficient ${pam_ldap}/lib/security/pam_ldap.so"}
${optionalString config.krb5.enable
"password sufficient ${pam_krb5}/lib/security/pam_krb5.so use_first_pass"}
${optionalString config.services.samba.syncPasswordsByPam
"password optional ${pkgs.samba}/lib/security/pam_smbpass.so nullok use_authtok try_first_pass"}
# Session management.
session required pam_unix.so
${optionalString config.users.ldap.enable
"session optional ${pam_ldap}/lib/security/pam_ldap.so"}
${optionalString config.krb5.enable
"session optional ${pam_krb5}/lib/security/pam_krb5.so"}
${optionalString startSession
"session optional ${pkgs.systemd}/lib/security/pam_systemd.so"}
${optionalString forwardXAuth
"session optional pam_xauth.so xauthpath=${pkgs.xorg.xauth}/bin/xauth systemuser=99"}
${optionalString (limits != [])
"session required ${pkgs.pam}/lib/security/pam_limits.so conf=${makeLimitsConf limits}"}
'';
target = "pam.d/${name}";
};
in
{
###### interface
options = {
security.pam.loginLimits = mkOption {
default = [];
example =
[ { domain = "ftp";
type = "hard";
item = "nproc";
value = "0";
}
{ domain = "@student";
type = "-";
item = "maxlogins";
value = "4";
}
];
description =
'' Define resource limits that should apply to users or groups.
Each item in the list should be an attribute set with a
<varname>domain</varname>, <varname>type</varname>,
<varname>item</varname>, and <varname>value</varname>
attribute. The syntax and semantics of these attributes
must be that described in the limits.conf(5) man page.
'';
};
security.pam.services = mkOption {
default = [];
example = [
{ name = "chsh"; rootOK = true; }
{ name = "login"; startSession = true; allowNullPassword = true;
limits = [
{ domain = "ftp";
type = "hard";
item = "nproc";
value = "0";
}
];
}
];
description =
''
This option defines the PAM services. A service typically
corresponds to a program that uses PAM,
e.g. <command>login</command> or <command>passwd</command>.
Each element of this list is an attribute set describing a
service. The attribute <varname>name</varname> specifies
the name of the service. The attribute
<varname>rootOK</varname> specifies whether the root user is
allowed to use this service without authentication. The
attribute <varname>startSession</varname> specifies whether
systemd's PAM connector module should be used to start a new
session; for local sessions, this will give the user
ownership of devices such as audio and CD-ROM drives. The
attribute <varname>forwardXAuth</varname> specifies whether
X authentication keys should be passed from the calling user
to the target user (e.g. for <command>su</command>).
The attribute <varname>limits</varname> defines resource limits
that should apply to users or groups for the service. Each item in
the list should be an attribute set with a
<varname>domain</varname>, <varname>type</varname>,
<varname>item</varname>, and <varname>value</varname> attribute.
The syntax and semantics of these attributes must be that described
in the limits.conf(5) man page.
'';
};
security.pam.enableSSHAgentAuth = mkOption {
default = false;
description =
''
Enable sudo logins if the user's SSH agent provides a key
present in <filename>~/.ssh/authorized_keys</filename>.
This allows machines to exclusively use SSH keys instead of
passwords.
'';
};
};
###### implementation
config = {
environment.systemPackages =
# Include the PAM modules in the system path mostly for the manpages.
[ pkgs.pam ]
++ optional config.users.ldap.enable pam_ldap
++ optional config.krb5.enable [pam_krb5 pam_ccreds];
environment.etc =
map makePAMService config.security.pam.services
++ singleton
{ source = otherService;
target = "pam.d/other";
};
security.setuidOwners = [ {
program = "unix_chkpwd";
source = "${pkgs.pam}/sbin/unix_chkpwd.orig";
owner = "root";
setuid = true;
} ];
security.pam.services =
# Most of these should be moved to specific modules.
[ { name = "cups"; }
{ name = "ejabberd"; }
{ name = "ftp"; }
{ name = "i3lock"; }
{ name = "lshd"; }
{ name = "samba"; }
{ name = "vlock"; }
{ name = "xlock"; }
{ name = "xscreensaver"; }
];
};
}