Provided by: policykit-1_0.104-1_amd64 bug

NAME

       polkit - Authorization Framework

OVERVIEW

       PolicyKit provides an authorization API intended to be used by privileged programs
       (“MECHANISMS”) offering service to unprivileged programs (“CLIENTS”) through some form of
       IPC mechanism such as D-Bus or Unix pipes. In this scenario, the mechanism typically
       treats the client as untrusted. For every request from a client, the mechanism needs to
       determine if the request is authorized or if it should refuse to service the client. Using
       the PolicyKit API, a mechanism can offload this decision to a trusted party: The PolicyKit
       Authority.

       In addition to acting as an authority, PolicyKit allows users to obtain temporary
       authorization through authenticating either an administrative user or the owner of the
       session the client belongs to. This is useful for scenarios where a mechanism needs to
       verify that the operator of the system really is the user or really is an administrative
       user.

SYSTEM ARCHITECTURE

       The system architecture of PolicyKit is comprised of the Authority (implemented as a
       service on the system message bus) and a Authentication Agent per user session (provided
       and started by the user session e.g. GNOME or KDE). Additionally, PolicyKit supports a
       number of extension points – specifically, vendors and/or sites can write extensions to
       completely control authorization policy. In a block diagram, the architecture looks like
       this:

           [IMAGE][1]

                +-------------------+
                |   Authentication  |
                |       Agent       |
                +-------------------+
                | libpolkit-agent-1 |
                +-------------------+
                       ^                                  +--------+
                       |                                  | Client |
                       +--------------+                   +--------+
                                      |                        ^
                                      |                        |
               User Session           |                        |
               =======================|========================|=============
               System Context         |                        |
                                      |                        |
                                      |                    +---+
                                      V                    |
                                    /------------\         |
                                    | System Bus |         |
                                    \------------/         |
                                      ^        ^           V
                                      |        |      +---------------------+
                       +--------------+        |      |      Mechanism      |
                       |                       |      +---------------------+
                       V                       +----> | libpolkit-gobject-1 |
               +------------------+                   +---------------------+
               | org.freedesktop. |
               |    PolicyKit1    |
               +------------------+
               |   Backends and   |
               |    Extensions    |
               +------------------+

       For convenience, the libpolkit-gobject-1 library wraps the PolicyKit D-Bus API using
       GObject. However, a mechanism can also use the D-Bus API or the pkcheck(1) command to
       check authorizations.

       The libpolkit-agent-1 library provides an abstraction of the native authentication system,
       e.g.  pam(8) and also facilities registration and communication with the PolicyKit D-Bus
       service.

       PolicyKit extensions and authority backends are implemented using the libpolkit-backend-1
       library.

       See the developer documentation[2] for more information about using and extending
       PolicyKit.

       See pklocalauthority(8) for information about the Local Authority - the default authority
       implementation shipped with PolicyKit.

AUTHENTICATION AGENTS

       An authentication agent is used to make the user of a session prove that the user of the
       session really is the user (by authenticating as the user) or an administrative user (by
       authenticating as a administrator). In order to integrate well with the rest of the user
       session (e.g. match the look and feel), authentication agents are meant to be provided by
       the user session that the user uses. For example, an authentication agent may look like
       this:

           [IMAGE][3]

               +----------------------------------------------------------+
               |                     Authenticate                     [X] |
               +----------------------------------------------------------+
               |                                                          |
               |  [Icon]  Authentication is required to run ATA SMART     |
               |          self tests                                      |
               |                                                          |
               |          An application is attempting to perform an      |
               |          action that requires privileges. Authentication |
               |          as the super user is required to perform this   |
               |          action.                                         |
               |                                                          |
               |          Password for root: [_________________________]  |
               |                                                          |
               | [V] Details:                                             |
               |  Drive:  ATA INTEL SSDSA2MH08 (045C)                     |
               |  Device: /dev/sda                                        |
               |  Action: org.fd.devicekit.disks.drive-ata-smart-selftest |
               |  Vendor: The DeviceKit Project                           |
               |                                                          |
               |                                  [Cancel] [Authenticate] |
               +----------------------------------------------------------+

       If the system is configured without a root account it may allow you to select the
       administrative user who is authenticating:

           [IMAGE][4]

               +----------------------------------------------------------+
               |                     Authenticate                     [X] |
               +----------------------------------------------------------+
               |                                                          |
               |  [Icon]  Authentication is required to run ATA SMART     |
               |          self tests                                      |
               |                                                          |
               |          An application is attempting to perform an      |
               |          action that requires privileges. Authentication |
               |          as one of the users below is required to        |
               |          perform this action.                            |
               |                                                          |
               |          [[Face] Patrick Bateman (bateman)         [V]]  |
               |                                                          |
               |          Password for bateman: [______________________]  |
               |                                                          |
               | [V] Details:                                             |
               |  Drive:  ATA INTEL SSDSA2MH08 (045C)                     |
               |  Device: /dev/sda                                        |
               |  Action: org.fd.devicekit.disks.drive-ata-smart-selftest |
               |  Vendor: The DeviceKit Project                           |
               |                                                          |
               |                                  [Cancel] [Authenticate] |
               +----------------------------------------------------------+

       See pklocalauthority(8) on how to set up the local authority implemention for systems
       without a root account.

DECLARING ACTIONS

       A mechanism need to declare a set of “ACTIONS” in order to use PolicyKit. Actions
       correspond to operations that clients can request the mechanism to carry out and are
       defined in XML files that the mechanism installs into the /usr/share/polkit-1/actions
       directory.

       PolicyKit actions are namespaced and can only contain the characters [a-z][0-9].- e.g.
       lower-case ASCII, digits, period and hyphen. Each XML file can contain more than one
       action but all actions need to be in the same namespace and the file needs to be named
       after the namespace and have the extension .policy.

       The XML file must have the following doctype declaration

           <?xml version="1.0" encoding="UTF-8"?>
           <!DOCTYPE policyconfig PUBLIC "-//freedesktop//DTD PolicyKit Policy Configuration 1.0//EN"
           "http://www.freedesktop.org/standards/PolicyKit/1.0/policyconfig.dtd">

       The policyconfig element must be present exactly once. Elements that can be used inside
       policyconfig includes:

       vendor
           The name of the project or vendor that is supplying the actions in the XML document.
           Optional.

       vendor_url
           A URL to the project or vendor that is supplying the actions in the XML document.
           Optional.

       icon_name
           An icon representing the project or vendor that is supplying the actions in the XML
           document. The icon name must adhere to the Freedesktop.org Icon Naming
           Specification[5]. Optional.

       action
           Declares an action. The action name is specified using the id attribute and can only
           contain the characters [a-z][0-9].- e.g. lower-case ASCII, digits, period and hyphen.

       Elements that can be used inside action includes:

       description
           A human readable description of the action, e.g.  “Install unsigned software”.

       message
           A human readable message displayed to the user when asking for credentials when
           authentication is needed, e.g.  “Installing unsigned software requires
           authentication”.

       defaults
           This element is used to specify implicit authorizations for clients.

           Elements that can be used inside defaults includes:

           allow_any
               Implicit authorizations that apply to any client. Optional.

           allow_inactive
               Implicit authorizations that apply to clients in inactive sessions on local
               consoles. Optional.

           allow_active
               Implicit authorizations that apply to clients in active sessions on local
               consoles. Optional.

           Each of the allow_any, allow_inactive and allow_active elements can contain the
           following values:

           no
               Not authorized.

           yes
               Authorized.

           auth_self
               Authentication by the owner of the session that the client originates from is
               required.

           auth_admin
               Authentication by an administrative user is required.

           auth_self_keep
               Like auth_self but the authorization is kept for a brief period.

           auth_admin_keep
               Like auth_admin but the authorization is kept for a brief period.

       annotate
           Used for annotating an action with a key/value pair. The key is specified using the
           the key attribute and the value is specified using the value attribute. This element
           may appear zero or more times. See below for known annotations.

       vendor
           Used for overriding the vendor on a per-action basis. Optional.

       vendor_url
           Used for overriding the vendor URL on a per-action basis. Optional.

       icon_name
           Used for overriding the icon name on a per-action basis. Optional.

       For localization, description and message elements may occur multiple times with different
       xml:lang attributes.

       To list installed PolicyKit actions, use the pkaction(1) command.

   Known annotations
       The org.freedesktop.policykit.exec.path annotation is used by the pkexec program shipped
       with PolicyKit - see the pkexec(1) man page for details.

       The org.freedesktop.policykit.imply annotation (its value is a string containing a space
       separated list of action identifiers) can be used to define meta actions. The way it works
       is that if a subject is authorized for an action with this annotation, then it is also
       authorized for any action specified by the annotation. A typical use of this annotation is
       when defining an UI shell with a single lock button that should unlock multiple actions
       from distinct mechanisms.

       The org.freedesktop.policykit.owner annotation can be used to define a set of users who
       can query whether a client is authorized to perform this action. If this annotation is not
       specified then only root can query whether a client running as a different user is
       authorized for an action. The value of this annotation is a string containing a space
       separated list of PolkitIdentity entries, for example "unix-user:42 unix-user:colord". A
       typical use of this annotation is for a daemon process that runs as a system user rather
       than root.

AUTHOR

       Written by David Zeuthen davidz@redhat.com with a lot of help from many others.

BUGS

       Please send bug reports to either the distribution or the polkit-devel mailing list, see
       the link http://lists.freedesktop.org/mailman/listinfo/polkit-devel on how to subscribe.

SEE ALSO

       pklocalauthority(8) polkitd(8) pkaction(1), pkcheck(1), pkexec(1),

NOTES

        1. /usr/share/gtk-doc/html/polkit-1/polkit-architecture.png

        2. developer documentation
           file:///usr/share/gtk-doc/html/polkit-1/index.html

        3. /usr/share/gtk-doc/html/polkit-1/polkit-authentication-agent-example.png

        4. /usr/share/gtk-doc/html/polkit-1/polkit-authentication-agent-example-wheel.png

        5. Freedesktop.org Icon Naming Specification
           http://standards.freedesktop.org/icon-naming-spec/icon-naming-spec-latest.html