You won’t need polkit anymore!

… to compile polkit-qt-1!

So, after I got your attention with the tabloid-style headline, let’s make a bit less shocking point of the current situation, or “What did I do during summer?”. 🙂

First of all, please let me apologize for the time it took me to at least put up a summary of my project, I was (and still am, but it’s getting better every day) sick past few weeks and finally getting into a more “alive” shape.

Well, if I could make it in one sentence, it would be something along the lines of “I hacked libpolkit out of polkit-qt-1”. But that’s not all, let’s jump on the longer version of the story:

After playing around with the D-Bus classes in Qt a little bit, I tried generating bindings for the org.freedesktop.PolicyKit1.Authority interface. Of course it didn’t work initially but very soon I had a working connection and could call some methods. This success led me into believing I could get rid of those nasty GLIB-based methods in our library (Hey, it’s called polkit-qt-1, not polkit-qt-glib-1!).

The progress

I was very naive because I thought it could be done quickly.

There were various bumps on the road (and still will be) but the biggest ones were caused by my stupidity so no big deal implementation-wise really.

For example – I had wrong QDBusArgument streaming operators for the Identity class, resulting in having a different signature for a slot on the AuthenticationAgent adaptor, which then of course ended up in the authority not being able to call BeginAuthentication correctly because of a wrong method signature. I’m not sure how I found out but Qt definitely wasn’t helping me. Which I can illustrate by this: I found out about the QTDBUS_DEBUG environment variable in a few small blogposts when I was googling about it but its documentation is almost nonexistent.

The most recent state is in the noglib branch of my personal clone (mbriza/gsoc13-polkit-qt-1). The last commit I had when GSoC ended is the biggest one, currently about 1400 additions and 1300 deletions. From now on, I’ll commit the changes incrementally and stop modifying this one.

As the changes that will be introduced by these commits will be quite consistent as one and depend on each other, there will be a single commit for the whole change. I don’t see purpose in splitting it – No part of the transition can be  done on its own and keep the functionality as a whole intact.

It works!

What I achieved so far with this is being able to run polkit-kde-authentication-agent-1 with the new library loaded and successfully authenticate for any action in the system… without crashes (whew).

Most of the project is now hooked on the D-Bus API –  this means the whole core and agent-listener. 

The agent-session is a tad different though – it’s an authentication backend wrapper which in a short means it wraps and mimics PAM conversation. Implementing such functionality would be a huge overkill so I stuck to usage of the session helper provided by polkit which is then communicating with the library using a really simple text-based protocol.

What needs to be done now

  • REVIEW 🙂
  • adding all missing features (from the tip of my pen, i’m pretty sure creating of subject and identity objects isn’t really valid)
  • completing D-Bus call handling (timed out, no reply, etc.)
  • adding support for the libpolkit API (which I’m kind of considering obsolete and seriously doubt anyone ever used the structures from libpolkit as parameters to polkit-qt-1 methods… but even though there is this doubt, the methods in question are part of the public API
  • fixing and cleaning up both the D-Bus adaptor and interface, ideally to the state when they can be automatically generated from the “XML”s provided by polkit upstream
  • finding the location of the polkit provided session helper properly
  • CMake magic to actually abandon libpolkit, e.g. to get rid of it altogether, even from the headers

KRunner UIKRunner asking for a password

As discussed in the previous posts, I also experimented with implementing the dialog as a runner, which went reasonably usable, except for the fact the password is displayed as a regular KRunner query.

This means I’ll have to convince the folks maintaining it to add a property or method to set input masking.

Having the password dialog in the textbox UI of KRunner means an improvement in user experience and simplification for end users. It’s also worth noting that simple disabling the runner will give the user access to the old way how dialogs were shown with all the advanced information.

There are a few variants on how to implement the final UI to be included, which will be of course discussed before any definitive decision is made. There are three different pieces of information we may want to display to the user.

  • The basic request description (yeah, we want this one for sure)
  • Extended description of the request
  • Message about why the hell the dialog popped from the top of the screen and what does it want from the user
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What’s up with polkit in Qt and KDE?

Jaroslav Řezník asked on #fedora-kde a few days ago if anyone was interested in taking over polkit-qt and polkit-kde-agent as he doesn’t have enough time to maintain them aside with his other duties and when I met him in the kitchen, we discussed the matter. He was very convincing with the reasons to take the package and made the ugly bugs seem really interesting so here I stand. 🙂

What I’m intending to do

Bug reports quite stacked in the tracker in the meantime so the plan how to deal with them in the following weeks is:

There’s a LOT of bug reports in the tracker for both components and it seems most of them were caused by the underlying libraries or misuse of the authentication agents as I wasn’t able to reproduce most of them. I’m requesting information from the reporters though to be sure and possibly work on solutions with them. Hopefully, Drs. Albert Spijkers will respond if Jawid Asefi and others died young or stopped attempting to hack him…  (https://bugs.kde.org/show_bug.cgi?id=316514)

Of course most of the reports are coming from software managers like Apper or Muon and looking into the reports, I’m afraid many bugs in polkit related packages were worked around in the invoking applications.

I already closed a few of them though, the ones confirmed to be fixed and the ones apparently caused by something else and fixed by now. However, it’s interesting how for every closed bug I receive an informative mail starting with “[Red Hat – Possible Forgery]” but the comments go through clear.

At the first glance it seems handling signals and cancellations may be done in a bit unlucky way in polkit-qt but I have to be sure before I’m making any chances to the code.

Usability

When I will have triaged most of the bugs, there will be time for some enhancements to the overall usability of the agent. Currently, there is a problem with the authentication dialog window appearing beneath the “parent” window (quotes because it’s technically not its parent) often causing the user to not notice he needs to enter a password to proceed and failing the authentication process.

Regarding this, Jaroslav spoke about moving the dialog into KRunner which would look very nice (maybe just my impression but I really like KRunner and think it should be used more). I’m leaving this for further discussion. And with that we can start right here, please tell me what you think about it in the comments!

Besides that, I think using the notifier area as KWallet is doing now would make the behavior nicely consistent with it as both components are quite closely related.

I also see there are some parts still unimplemented but planned, for example the “Remember authorization” checkbox or display of which application invoked the dialog. These are still planned and I’m going to implement them over time.

However, I won’t be doing anything about the KCM module for rule editing. I don’t even have rights for the repository and am not planning to obtain them. If you’re willing to take up the work and continue to maintain the project, you’re free and welcome to do so!