SYNOPSIS
pkexec [--version] [--help]
pkexec [--user username] PROGRAM [ARGUMENTS...]
DESCRIPTION
pkexec allows an authorized user to execute PROGRAM as another user. If
username is not specified, then the program will be executed as the
administrative super user, root.
RETURN VALUE
Upon successful completion, the return value is the return value of
PROGRAM. If the calling process is not authorized or an authorization
could not be obtained through authentication or an error occured,
pkexec exits with a return value of 127.
SECURITY NOTES
Executing a program as another user is a privileged operation. By
default the required authorization (See the section called "REQUIRED
AUTHORIZATIONS") requires administrator authentication. In addition,
the authentication dialog presented to the user will display the full
path to the program to be executed so the user is aware of what will
happen:
[IMAGE][1]
+----------------------------------------------------------+
| Authenticate [X] |
+----------------------------------------------------------+
| |
| [Icon] Authentication is needed to run `/bin/bash' |
| as the super user |
| |
| 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: |
| Command: /bin/bash |
| Run As: Super User (root) |
| Action: org.freedesktop.policykit.exec |
| Vendor: The PolicyKit Project |
| |
| [Cancel] [Authenticate] |
+----------------------------------------------------------+
The environment that PROGRAM will run it, will be set to a minimal
known and safe environment in order to avoid injecting code through
LD_LIBRARY_PATH or similar mechanisms. In addition the PKEXEC_UID
environment variable is set to the user id of the process invoking
To specify what kind of authorization is needed to execute the program
/usr/bin/pk-example-frobnicate as another user, simply write an action
definition file like this
<?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/policyconfig.dtd">
<policyconfig>
<vendor>Examples for the PolicyKit Project</vendor>
<vendor_url>http://hal.freedesktop.org/docs/PolicyKit/</vendor_url>
<action id="org.freedesktop.policykit.example.pkexec.run-frobnicate">
<description>Run the PolicyKit example program Frobnicate</description>
<description xml:lang="da">Kor PolicyKit eksemplet Frobnicate</description>
<message>Authentication is required to run the PolicyKit example program Frobnicate</message>
<message xml:lang="da">Autorisering er pakraevet for at afvikle PolicyKit eksemplet Frobnicate</message>
<icon_name>audio-x-generic</icon_name>
<defaults>
<allow_any>no</allow_any>
<allow_inactive>no</allow_inactive>
<allow_active>auth_self_keep</allow_active>
</defaults>
<annotate key="org.freedesktop.policykit.exec.path">/usr/bin/pk-example-frobnicate</annotate>
</action>
</policyconfig>
and drop it in the /usr/share/polkit-1/actions directory under a
suitable name (e.g. matching the namespace of the action). Note that in
addition to specifying the program, the authentication message,
description, icon and defaults can be specified. For example, for the
action defined above, the following authentication dialog will be
shown:
[IMAGE][2]
+----------------------------------------------------------+
| Authenticate [X] |
+----------------------------------------------------------+
| |
| [Icon] Authentication is required to run the PolicyKit |
| example program Frobnicate |
| |
| An application is attempting to perform an |
| action that requires privileges. Authentication |
| is required to perform this action. |
| |
| Password: [__________________________________] |
| |
| [V] Details: |
| Command: /usr/bin/pk-example-frobnicate |
| Run As: Super User (root) |
+----------------------------------------------------------+
| |
| [Icon] Autorisering er pakraevet for at afvikle |
| PolicyKit eksemplet Frobnicate |
| |
| Et program forsoger at udfore en handling der |
| kraever privilegier. Autorisering er pakraevet. |
| |
| Kodeord: [___________________________________] |
| |
| [V] Detaljer: |
| Bruger: Super User (root) |
| Program: /usr/bin/pk-example-frobnicate |
| Handling: org.fd.pk.example.pkexec.run-frobnicate |
| Vendor: Examples for the PolicyKit Project |
| |
| [Annuller] [Autorisering] |
+----------------------------------------------------------+
Note that pkexec does no validation of the ARGUMENTS passed to PROGRAM.
In the normal case (where administrator authentication is required
every time pkexec is used), this is not a problem since if the user is
an administrator he might as well just run pkexec bash to get root.
However, if an action is used for which the user can retain
authorization (or if the user is implicitly authorized), such as with
pk-example-frobnicate above, this could be a security hole. Therefore,
as a rule of thumb, programs for which the default required
authorization is changed, should never implicitly trust user input
(e.g. like any other well-written suid program).
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
polkit(8), pkaction(1), pkcheck(1)
NOTES
1. /usr/share/gtk-doc/html/polkit-1/pkexec-bash.png
2. /usr/share/gtk-doc/html/polkit-1/pkexec-frobnicate.png
3. /usr/share/gtk-doc/html/polkit-1/pkexec-frobnicate-da.png
|
