Re: [gdm-list] [RFE] A modular gdm greeter

[Oswald Buddenhagen <ossi kde org>]

On Thu, Oct 04, 2007 at 03:18:54PM -0500, Brian Cameron wrote:
> For example, if you need to pick domain, username, and password for
> PAM to authenticate, and you wanted a custom widget to get the domain
> information from the user, then you could make it work as follows:
> 
> The PAM module could detect if the login program has the special
> domain GUI plugin.  If so, then it avoids asking for domain via PAM
> and instead gets the information from the GUI plugin directly.  If the
> GUI doesn't support the special domain GUI plugin, then it asks for
> domain over normal PAM protocols.
> 
> But for this to work, it probably requires a special PAM module that
> knows how to talk to the GUI, right?
> 
wrong. the ui plugin just reads the regular conversation prompts and
processes them adequately, usually auto-answering them. if multiple
inputs are needed and are expected to be entered in parallel, the
plugin needs to know this in advance and would not start/continue the
actual pam conversation until everything is available.

> > The 2 stacks idea seem interesting seeing it under this PoV, it is worth
> > thinking about it, but just letting plugins handle the PAM conversation
> > may do as well.
> > Smart plugins my use expect-like methods to know what to do in specific
> > configurations.
> 
> Remember PAM is not multi-threaded, so if GUI plugins handle PAM
> conversations, then each plugin would either need to be in a separate
> process or you would need some way to ensure only one plugin at a time
> talks to PAM.
> This sounds hard.
>
actually, it sounds wrong. :-P
the pam stacks need to run in separate processes. however, the ui
plugins are just widgets that are plugged into the ui and connected with
some signals, thus nicely playing with the event loop. no need to
multi-thread anything here. the only important thing is to make every
plugin talk to *his* stack process. but i don't think this is a problem.

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