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

Lennart Poettering lennart at poettering.net
Thu Feb 9 13:29:38 PST 2012

On Thu, 09.02.12 20:57, Christian Hesse (list at eworm.de) wrote:

> > Yes, there have been similar reports.
> Glad to hear I am not the only one... Could not find any reports so
> far.

There were a couple on #systemd.

> > 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.

> I suppose testing with kdm and/or gdm does not help, does it? I am pretty
> sure my pam setup is ok.

Well, any client that exposes the problem is fine.


Lennart Poettering - Red Hat, Inc.

More information about the systemd-devel mailing list