[LightDM] [PATCHES] Multiple prompts in a single PAM conversation round

[Christian Seiler]

Hi,

when using pam_krb5, I've run into the following problem w.r.t to lightdm:

If a user's password is set to expire, i.e. the user needs to change it
the first time they log in again, pam_krb5 will ask for the new password
and the repeated version of the new password during the authentication
phase (before authentication is complete). For this it uses two prompts
in the same PAM conversation round. This is in principle handled
properly in LightDM on the server side, but neither the GTK nor the KDE
greeter implement this properly. (I haven't tried any other, but I
suspect they suffer from the same problem.)

The first patch modifies liblightdm-gobject and liblightdm-qt to provide
an additional signal that allows the greeter to know that all
prompt/message signals for the specific conversation round have been
processed. The second patch modifies lightdm-gtk-greeter to make use of
it (while still allowing it to be compiled and/or run against older
versions of liblightdm-gobject). I plan on looking at the KDE greeter
next, the GTK one was just the simplest one to patch in this context.

Regards,
Christian

PS: I'm not subscribed to the mailing list, so please put me on Cc for
replies.

PPS: Since this is my first time doing something with bzr (I mainly use
git and have dabbled in mercurial), I'm sorry if I don't know the proper
etiquette for providing patches. For now I have attached the output
generated by bzr send -o (I recon this is similar to git format-patch?)
to this email, but if you prefer a different style (inline, as
attachments in the bugtracker, ...), please let me know.
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