If you won't find a solution, you might want to try pam_exec. <div class="gmail_quote"><div dir="ltr">On Sun, Jan 15, 2017, 02:27 David Llewellyn-Jones <<a href="mailto:david@flypig.co.uk">david@flypig.co.uk</a>> wrote: </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">On 13/01/17 15:47, Bastien Nocera wrote: > On Fri, 2017-01-13 at 14:37 +0000, David Llewellyn-Jones wrote: >> >> I've been experiencing strange behaviour connecting to the system bus >> from a pam module. This is on Ubuntu 16.04 using gdbus and gdbus- >> codegen >> for both the caller and listening service. >> [snip - gdbus details] >> Does anyone have any suggestion for why this might be happening? > > GDBus's threads and PAM really don't mix. You'll need to either use > something like dbus-glib, which is single-threaded and sync, move your > D-Bus code to a small helper you'd talk to over Unix sockets (yeah, I > know...), or wait until PAM dies. > > FWIW, this problem is one of the reasons why fprintd (and pam_fprintd) > is written using dbus-glib rather than GDBus. I've attempted to convert the pam module to use dbus-glib, using your pam_fprintd.c code as a template (which has been very helpful, thank you!). Unfortunately I'm still running in to problems. After removing all of the previous gdbus code and replacing it with the following dbus-glib code, I now get segfaults occurring. ------- GError * error = NULL; DBusGConnection * connection; connection = dbus_g_bus_get (DBUS_BUS_SYSTEM, &error); if (connection == NULL) { syslog(LOG_ERR, "pam_test: connection error: %s\n", error->message); g_clear_error (&error); } else { dbus_g_connection_unref (connection); } ------- Originally I had a more complete set of code following this, but I found the above was enough to trigger the problem. Here's the code on github: <a href="https://github.com/llewelld/dbus-pam-test/blob/5940e11d939f587a7c1b42c00a02d0a5cc7dc2c3/src/pam_test.c#L131" rel="noreferrer" class="gmail_msg" target="_blank">https://github.com/llewelld/dbus-pam-test/blob/5940e11d939f587a7c1b42c00a02d0a5cc7dc2c3/src/pam_test.c#L131</a> and here's the segfault entry from syslog: Jan 14 23:12:17 Owen kernel: [ 4683.886530] compiz[11249]: segfault at 7f34cd0ac8a0 ip 00007f34f8692908 sp 00007ffe6e955970 error 4 in libglib-2.0.so.0.4800.1[7f34f8649000+10f000] Am I doing something wrong? In case it's important, the segfault doesn't occur the first time the module is run, but consistently when it's called for a second time. Again, this is all using the Unity lockscreen on Ubuntu 16.04. David -- Website: <a href="http://www.flypig.co.uk" rel="noreferrer" class="gmail_msg" target="_blank">http://www.flypig.co.uk</a> _______________________________________________ dbus mailing list <a href="mailto:dbus@lists.freedesktop.org" class="gmail_msg" target="_blank">dbus@lists.freedesktop.org</a> <a href="https://lists.freedesktop.org/mailman/listinfo/dbus" rel="noreferrer" class="gmail_msg" target="_blank">https://lists.freedesktop.org/mailman/listinfo/dbus</a> </blockquote></div>