[systemd-devel] systemd v4[01] and graphical login managers

[Christian Hesse]

Lennart Poettering <lennart at poettering.net> on Fri, 10 Feb 2012 21:02:03
+0100:
> On Fri, 10.02.12 09:48, Christian Hesse (list at eworm.de) wrote:
> 
> > 
> > Lennart Poettering <lennart at poettering.net> on Thu, 9 Feb 2012 22:29:38
> > +0100:
> > > On Thu, 09.02.12 20:57, Christian Hesse (list at eworm.de) wrote: 
> > > > > systemd-logind tracks open sessions by keeping open a FIFO fd to
> > > > > the PAM session client. When the session client dies then systemd
> > > > > will see that as EOF. Now, if the PAM client side eagerly closes
> > > > > all fds it finds this will trigger an immediate end of session.
> > > > 
> > > > Can I help tracking this down? Let me know what to do.
> > > 
> > > Well, strace the PAM client which invokes the PAM session hooks and
> > > figure out where exactly the fifo is closed and by what piece of
> > > code. The FIFO fd is received via a dbus reply (which you'll see as a
> > > recvmsg() with an SCM_RIGHTS param, followed by an fcntl(F_DUPFD)), and
> > > you'd need to trace where it gets closed in the parent process.
> > 
> > Here is my trace:
> > http://www.eworm.de/tmp/lightdm.log
> > 
> > I think this is the code closing the fd:
> > http://bazaar.launchpad.net/~lightdm-team/lightdm/trunk/view/head:/src/pam-session.c#L393
> 
> Well, but normally the PAM session should only be closed after the user
> logged out again. Why is this invoked so early?

Looks like lightdm starts a root pam session for the greeter. That is closed
before the user pam session ist started...
Sounds wired - hope I will find some time to take a look at the code. Anybody
here familiar with pam clients?

Anyway... slim is not split into core and greeter. Does it act the same
nevertheless? Will take a look at that, too.
-- 
Best regards,
Chris
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