Subject: Re: [X2Go-User] Session resume fails with AFS home directories

From: Sebastian Flothow <[email-masked]>
Date: Mon, 29 Jul 2013 13:06:34 +0200

Am 26.07.2013 16:40, schrieb Mike Gabriel:
> Package: x2goserver
> Version: 4.0.1.3

By now it's 4.0.1.6-0~x2go1+wheezy~main~712~build1, but the problem 
persists.

> Is there any environment variable that we have to set before we can
> access the home directory of the user?
>
> My guess is that we have to set at least
>
>    export KRB5CCNAME=???
>
> Maybe any other env var for the AFS token?

No, that should not be necessary. KRB5CCNAME is set by pam_krb5.so. 
pam_afs_session.so in turn uses this to obtain an AFS token, then 
associates it with a new Process Authentication Group. The PAG ID is 
stored in the group array for the session, i.e. "id" shows an additional 
artificial group id. In fact this all works flawlessly on initial login, 
it's only on resume where it fails.

It occurs to me now that both KRB5CCNAME and PAG are per-session rather 
than per-user, so that might be the cause for this problem (but I'm 
really just guessing here).

Is there a detailed description of the resume process? Does it involve 
any shell scripts or similar I could hook into in order to log 
additional information?

I'm attaching /var/log/user.log as well as the client output from a 
failed resume attempt, maybe this offers some clues.

Thanks,
Sebastian