Re: [gdm-list] George & Martin - update about GDM

[Lukasz Zalewski <lukas dcs qmul ac uk>]

Jiri Lebl wrote:
> Brian Cameron wrote:
> > Earlier this year William Jon McCann (he goes by Jon) started an effort
> > to rewrite GDM to use D-Bus as its IPC mechanism and to use gobjects for
> > better maintainability, reusability, etc.  The GNOME community is very
> > interested in moving in this direction, mostly because everyone in
> > GNOME loves D-Bus, I guess.  Jon's code is reaching a point where it
> > is starting to be usable, and plans are to make the next unstable
> > release of GDM (2.21) based on his code.
>
> My opinion would be the following.  D-Bus is great, but if I were still doing
> the work, I doubt I would use it for the internal communication.  Internal
> chatter between slaves, master, greeters has no need to be "standard" in any
> sort of way.  It needs to just be as simple as possible to avoid security
> problems.
>
> Plus I have grown to be supporter of the thesis that upgrades should not
> break previously working configurations, and should not decrease the feature
> set if this feature set is in wide use.  The user doesn't care about internal
> organization of the code.  Rewriting a piece of code using the current "in
> vogue" model is generally pointless in my opinion and usually just pisses of
> the users.  The new version might have all the new buzzwords in it's design,
> but doesn't do half the stuff they are used to.  Think of people running
> large labs who have custom gdm configurations.  They really won't be too
> happy about having to change config and retest all their config and possibly
> run older versions of gdm if the new setup doesn't work, just because the new
> version was rewritten and only half the old feature set is working.
>
> Finally there is the question of security.  Rewriting large parts of the core
> should require a security audit!  Security issues tend to be subtle and
> obscure, and tend to be harder to find in more complicaled code (i.e.
> dbus/gobject/etc...)  I did not on purpose change the design to GObjects when
> I took over gdm.  Martin's design was essentially sound, so I stuck with it.
>  If you rewrite large parts of the core, be prepared for several new security
> issues to pop up soon.  (plus you really should have someone do a thorough
> security audit on new code)  Remember this code runs as "root" and can do
> VERY evil things.  Undiscovered security holes are just as bad as discovered
> ones.
>
> That's just my opinion.
>
> > If you have the time and interest, it would be useful to get thoughts
> > about this rewrite from you past maintainers.  It would be useful to
> > hear your thoughts on how you think these changes will impact security,
> > any gotchas that you can foresee, etc.
>
> One gotcha that I can think of from the top of my head, is more trouble with
> signals in the new setup.  Note that the slave is synchroneous and must
> communicate with signals.  Unless you fix this synchroneity (which is very
> subtle, you must catch ALL instances where the process could possibly hang
> and split of a new process or thread) more complicated code is more likely to
> get into subtle race conditions with signals.
>
> Do worry about race conditions coming up.
>
> > For the time being, plans are to drop support for gdmgreeter and
> > possibly gdmsetup, though I would imagine they will be added back
> > if someone has enough interest and love to port them to the new
> > frameworks.  There is one fellow named Lukasz, who has suggested he
> > might port gdmsetup, but I'm not sure how serious he is yet.
>
> Since most distros/users use gdmgreeter shouldn't lack of gdmgreeter be
> considered a big regression?
>
> As for gdm setup, you mean there won't even be a way to support a gui
> configuration?  That does sound like a BIG regression for gnome.

There will be a gdmsetup equivalent :) and hopefully also an equivalent 
 of gdmgreeter
> > George, another thing I wanted to mention to you is that William
> > believes that he was rewritten (almost) all the code that existed
> > before I became maintainer.  There are a few small bits of older
> > code still lying around.  William and other involved people have
> > expressed they want to drop the Queen of England as maintainer and
> > copyright owner.  George, I believe it was you who added the Queen as
> > maintainer and copyright holder.  Is that right?
>
> If he wants to actually and truly rewrite all the code just because the
> copyright holder is queen of england, I would have him (and others who hold
> this opinion) to check with a psychiatrist.  Queen of England was given the
> maintainership precisely to piss off ego centric people who want to put their
> name up on a pedestal.  It was also to piss off anyone who was unreasonably
> serious.
>
> Anyway, the copyright cannot be legally held by queen of england anyway, and
> is held by me if you really want to purge her name from there.  Since I don't
> work on gdm anymore I don't care what you guys do with her.  Although I don't
> see any harm in having Queen of England in the list of copyright holders
> instead of me.  But feel free to purge her name, and really don't rewrite
> things for such a stupid reason.
>
> > If so, I wanted to ask your thoughts about this.  Would you be
> > willing to drop the Queen as maintainer and copyright holder of
> > the older bits of code that you worked on?  If so, this would
> > allow the project to keep the older code and avoid current plans
> > to rewrite it.  Whatever your thoughts on the matter, it might be
> > useful if you could send an email to gdm-list gnome org and let
> > people know what you think about this.  It might also be useful
> > if you were to look over the new code and verify whether you
> > agree that the older code owned by the Queen has been removed
> > as William believes.
>
> I would actually doubt that all this code (that I did from the time I took
> over until you did) has been rewritten.  But I don't care, feel free to
> remove the queen if there is a sufficient contingent of real coders lacking
> the sense of humor.
>
> George