Policy Kit - .conf
Desktop Apps Training - Policy Kit

PolicyKit.conf

PolicyKit.conf — PolicyKit configuration file

  

DESCRIPTION

The /etc/PolicyKit/PolicyKit.conf configuration file provides a way for system administrators to override policy for mechanisms that use the PolicyKit library to determine whether a caller is allowed to use the mechanism.

Changes to this configuration file are immediately propagated to running processes using the PolicyKit library. If the configuration file is invalid, processes using this library will log this fact to the system logger and the library will only only return no as the answer to processes using it.

The polkit-config-file-validate(1) tool can be used to verify that the configuration file is valid.

FILE FORMAT

The configuration file is an XML document. It must have the following doctype declaration: 

      
<!DOCTYPE pkconfig PUBLIC 
 "-//freedesktop//DTD PolicyKit Configuration 1.0//EN"
 "http://hal.freedesktop.org/releases/PolicyKit/1.0/config.dtd">

The following elements may be present in the configuration file:

config

This is the root element. A single attribute version must be present and must be set to "0.1" at this point. There can only be one config element in the configuration file.

match

This element is for matching information related to the decision making process and includes values describing both the caller and the action. This element can be embedded in both config and other match elements (hence allowing for nested matching).

There can only be a single attribute in each match element and POSIX Extended Regular Expression syntax are supported in the value part. The following attributes are supported:

user

This matches on the users login name.

action

For matching on the given action being queried for, for example action="org.foo.*" will match on all actions whose action identifier begins with the string "org.foo.".

return

This element is for used to specify what result the PolicyKit library will return. It can only be embedded in config and match elements and can embed no elements itself. The return element is typically used deeply inside a number of match elements. A single attribute, result is supported and it can assume the following values:

no

Access denied.

auth_self

Access denied, but authentication of the caller as himself will grant access to only that caller.

auth_self_keep_session

Access denied, but authentication of the caller as himself will grant access to any caller in the session of the caller belongs to.

auth_self_keep_always

Access denied, but authentication of the caller as himself will grant access any caller with the given uid in the future.

auth_admin

Access denied, but authentication of the caller as an administrative user will grant access to only that caller.

auth_admin_keep_session

Access denied, but authentication of the caller as an administrative user will grant access to any caller in the session of the caller belongs to.

auth_admin_keep_always

Access denied, but authentication of the caller as an administrative user will grant access any caller with the given uid in the future.

yes

Access granted.

define_admin_auth

This element is used to specify the meaning of "authenticate as administrator". It is normally used at the top-level but can also be used deep inside a number of match elements for conditional behavior.

There can only be a single attribute in each define_admin_auth element. POSIX Extended Regular Expression syntax is not supported in the value part, however multiple values to match on can be separated with the bar (|) character. The following attributes are supported:

user

Administrator authentication means authenticate as the given user(s). If no define_admin_auth element is given, the default is to use user="root" e.g. administrator authentication mean authenticate as the super user.

group

Administrator authentication means that any user in the groups matching the given value can be used to authenticate. Typically, on a system with the root account disabled one wants to use something like group="wheel" to e.g. enable all UNIX users in the UNIX group wheel to be able to authentication whenever administrator authentication is required.

EXAMPLES

For brevity, the standard XML and DOCTYPE headers as well as the top-level config are omitted in the following configuration file examples. The actions used may also be fictional, use polkit-action(1), to learn about the actions available on your system.

ALLOW EVERYTHING

The users "davidz" and "bateman" are allowed to do any action: 

        
<match user="davidz|bateman">
  <return result="yes"/>
</match>

MOUNTING FIXED DRIVES

Suppose the action org.freedesktop.hal.storage.mount-fixed is used to determine whether mounting internal hard drives are allowed. Then this configuration file 

        
<match action="org.freedesktop.hal.storage.mount-fixed">
  <match user="davidz">
    <return result="yes"/>
  </match>
  <match user="freddy">
    <return result="no"/>
  </match>
</match>

specifies that user "davidz" is always allowed to do the action, while user "freddy" is never allowed to do the action. Other users will be subject to the defaults results specified in the .policy file describing the action.

AVOIDING THE ROOT PASSWORD

Suppose the group wheel contains the users on a system who are allowed to carry out administrative tasks (ie. tasks that would usually require the root password) on a system where the root account is disabled. Then 

        
<define_admin_auth group="wheel"/>

can be used to specify that users in said group can authenticate using their own password in instances where the system would normally prompt for the root password.