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 4.0.1.13

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

Bug is archived. No further changes may be made.

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Subject: Bug#438: x2goserver and rhel6.4 / selinux Problem
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From: Mike Gabriel <mike.gabriel@das-netzwerkteam.de>
To: Frank Knoben <admin@igpm.rwth-aachen.de>
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[Message part 1 (text/plain, inline)]
Hi Frank,

On  Fr 28 Feb 2014 09:22:47 CET, Frank Knoben wrote:

> 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.

Nonono... I actually think there is something wrong with X2Go Server.

X2Go Client / PyHoca-GUI (another X2Go client app) should immitate  
what SSH does.

As the X2Go clients call the script /usr/bin/x2gostartagent and this  
script fiddles with the .Xauthority files via xauth, we should make  
sure that after modifying the .Xauthority file the SELinux permissions  
stay intact.

Can you please add your proposed chcon command into x2gostartagent  
(near line 268, there is another position further up for shadow  
sessions) after xauth has been called and see it that fixes your  
troubles.

Next step: please provide me with an if clause that will test if  
SELinux is in use or not, so we can call chcon only if SELinux is in  
use on that system.

Thanks+Greets,
Mike

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