X2Go Bug report logs - #438
x2goserver and rhel6.4 / selinux Problem

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Package: x2goserver; Maintainer for x2goserver is X2Go Developers <x2go-dev@lists.x2go.org>; Source for x2goserver is src:x2goserver.

Reported by: Frank Knoben <admin@igpm.rwth-aachen.de>

Date: Thu, 27 Feb 2014 09:10:02 UTC

Severity: normal

Tags: moreinfo, not-a-bug

Found in version

Done: Mike Gabriel <mike.gabriel@das-netzwerkteam.de>

Bug is archived. No further changes may be made.

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X-Loop: owner@bugs.x2go.org
Subject: Bug#438: x2goserver and rhel6.4 / selinux Problem
Reply-To: Frank Knoben <admin@igpm.rwth-aachen.de>, 438-quiet@bugs.x2go.org
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Date: Fri, 28 Feb 2014 09:22:47 +0100
From: Frank Knoben <admin@igpm.rwth-aachen.de>
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To: Mike Gabriel <mike.gabriel@das-netzwerkteam.de>, 
 438-quiet@bugs.x2go.org, 438@bugs.x2go.org
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[Message part 1 (text/plain, inline)]
Hello Mike,

the problem is, that I'm not an expert on selinux too.
But I did some more tests.

Interactive Session - first login, the ~/.Xauthority file is created
and stays after logout with the permissions *system_u:object_r:default_t:s0*
I am still able to login in interactively again.

But with this permissions, I got the Cookie mismatch problem, when using 
the x2goclient.
And when I login with ssh to the computer, I got a xauth error message:
/usr/bin/xauth:  ~/.Xauthority not writable, changes will be ignored

Now I  remove all .Xauthority* files. Then a login with ssh will create 
the ~/.Xauthority file
with the *system_u:object_r:xauth_home_t:s0* permissions and the files 
stays with
these permissions after logout.

Now when I use the x2goclient, the file permissions change during the 
login process from
*system_u:object_r:xauth_home_t:s0* to *system_u:object_r:default_t:s0 
*and stay
that way after logout. The same, as it is with interactive sessions.
So I guess, everything is fine with the x2goserver software and
this is not a bug.
My problem is, that ssh is not able to overwrite the .Xauthority file, 
when it has the
default permissions of *system_u:object_r:default_t:s0* . Therefore the 
x2goclient is
not able to start a successful session and gets the Cookie mismatch error.

So I think, you can close this bugreport.

Thank you very much for your quick response and please excuse my mistake in
thinking that this was a x2goserver bug.



Frank Knoben
Institut fuer Geometrie und Praktische Mathematik
RWTH Aachen

On 02/27/2014 04:30 PM, Mike Gabriel wrote:
> Control: tag -1 moreinfo
> Hi Frank,
>> ---------------------------
>> ls -Z .Xauthority
>>  -rw-------. frank users unconfined_u:object_r:default_t:s0 .Xauthority
>> --------------------------
>> Then I do a logout. Now, when I try to connect again to the x2go 
>> server system, I get
>> the following error message on the client side and no session is 
>> started.
>> -----------------------------
>> .....
>> "Warning: Cookie mismatch in the X authentication data.
>> "
>> "Session: Terminating session at 'Thu Feb 27 09:40:05 2014'.
>> Info: Your session was closed before reaching a usable state.
>> Info: This can be due to the local X server refusing access to the 
>> client.
>> Info: Please check authorization provided by the remote X application.
>> Session: Session terminated at 'Thu Feb 27 09:40:05 2014'.
>> "
>> deleting proxy
>> nxproxy not running
>> proxy deleted
>> -----------------------------------
>> But when I change the selinux permissions to
>> ------
>> ls -Z .Xauthority
>> -rw-------. frank users unconfined_u:object_r:xauth_home_t:s0 
>> .Xauthority
> What are the SELinux permissions after you have logged out?
> Do you need that chcon command call when resuming sessions or when 
> starting sessions.
> Excuse my SELinux innocence at this point. I would like to add support 
> for SELinux, but I need to understand better why we have to tweak the 
> security context of .Xauthority for X2Go.
> Thanks+Greets,
> Mike

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