[X2Go-Dev] Bug#459: PolicyKit authentication within apps often fails

[Michael DePaulo]

Package: x2goserver
Version: 4.0.1.13

Notes:

1. I am not sure if this is a bug in x2goserver, x2goserver-xsession,
or in nx-libs.

2. PolicyKit depends on ConsoleKit (and on systemd-logind in
newer distros.)

3. The behavior seems to be distro-specific and/or app-specific.

4. This bug report differs from 458 because PolicyKit authentication
is being called within an app, not when launching the app. This is
part of the PolilcyKit architecture: The apps run unprivileged and
rely on PolicyKit in order to speak to privileged processes that do
the actual task. For example, in test case 2, gpk-application is
launched unprivileged. It uses PolicyKit to speak to the PackageKit
backend, and the PackageKit backend does the package install.

Test system:
Fedora 20 64-bit
MATE Desktop 1.6.2.1.fc20 - used for all 3 test cases
x2goserver 4.0.1.13.2.fc20
x2goserver-xsession 4.0.1.13.2.fc20
nxlibs 3.5.0.22.1-fc20
(This distro uses logind)
(/usr/libexec/polkit-mate-authentication-agent-1 is launched
automatically when I login over X2Go. This distro is not affected by
bug 457)

Test Case 1:
Steps:
1. Launch yumex (from start menu or from console)
2. Switch to the yumex's "history" tab on the left..

Expected result:
A policykit authentication window opens up, I select a user to
authenticate as (myself or root), enter my password, and then the
history is populated within yumex.

Here is an image of that policykit authentication window:
http://imgur.com/JUZTBHo

Actual result:
The authentication window does not open up and the history is no
populated. Instead, I get an error message windows. When I click
"Close" on the window, yumex closes.

Error message:
Fatal Error: polkit-not-authorized

Could not get polkit autherisation to start backend

Yum Extender will terminate

Here's an image of the error message window
http://imgur.com/ABYETM0

>From the command-line, I can see this output when I select the history tab:
15:53:07 : INFO - YUM: Error executing command as another user: Not authorized
15:53:14 : INFO - yum backend process is ended
15:53:14 : INFO - yum backend process is ended

Test Case 2:
Steps:
1. Launch gpk-application (GNOME "Software Install" AKA "Add/Remove Software")
2. Select to install a single package.
3. Click "Apply Changes"

Expected result: A policykit authentication window opens up, I select
a user to authenticate as (myself or root), enter my password, and
then the package is downloaded & installed (over the course of at
least a few seconds), during which a progress bar is displayed.

Screenshot:
http://imgur.com/lLNof08

Actual result:
The authentication window does not open up. The progress bar for the
install completes in about 1 second. The package is not installed.
(Interestingly enough, the package is still selected to be installed,
but the "Apply Changes" and "cancel" button are hidden. This is a bug
in gpk-application, it does not know how to handle policykit having an
error. But this gpk-application bug is besides the point.)

Screenshot:
http://i.imgur.com/28lCZF5.png

Also, the command-line does not show any relevant output.

Test Case 3:
Steps:
1. Launch virt-manager (AKA "Virtual Machine Manager")

This test case actually passes!

Expected & Actual result:
A policykit authentication window opens up, I select a user to
authenticate as (e.g., myself or root), enter my password, and then I
am connected to the local libvirtd instance and see the VMs running.

Screenshot:
http://imgur.com/mZSgdMW

Also, the command-line output does not include any details about
PolicyKit (succeeding.)

Note: Test case 3 fails on CentOS 6.5 64-bit. However, CentOS 6.5
64-bit is affected by bug 457, so that precludes running this test
case.