pcsc-lite and the Gentoo diversion

You probably all know that I’m not really keen on diverging Gentoo from other distributions as long as it’s feasible, although I’m also always considering the idea of giving an extra edge to our distribution. Today, though, is one of the days when I have to implement something differently in Gentoo to have it working internally.

Today, Ludovic Rousseau released a new pcsc-lite version that is designed to improve autostart and increase safety and security by replacing a setuid-root with a setgit-pcscd. Together with that, a new ccid wrapper that sets the permission on USB devices via UDEV was released.

Now, while this looks all good stuff that improves user experience, this is mostly designed to solve issues with binary distributions — most likely, Ubuntu and derived. Autostart is mostly designed to avoid using a pcscd system service; in Gentoo that’s not much of a problem because it’s the user’s choice to start or not a init script, but on other distributions as soon as you install the package, the init script is scheduled to start. Once again, that’s not much of a problem when you install a server package, as that’s the whole point of it, but the pcscd service has to be bundled with the client library — and the client library is decided at build-time, so likely enabled for many packages, in those distributions. Again these aren’t enough of a concern for us, thanks to our customisable design.

On the other hand, the new design is troublesome for us: the daemons are started with the privileges of the current user, but access to the pcscd group; that would be okay if it wasn’t that it needs to create files in the /var/run/pcscd directory, which we cannot simply create in the ebuild – as /var/run could be on a tmpfs instance – and cannot simply be re-created by pcscd; it worked before because as setuid root it had all the privileges to do so. Ludovic suggested to create a reduced init script whose only task is to create the directory at startup, but at that point, why reducing to simply creating the directory?

The end result is as follows: the init script is updated, it creates the directory, alright, but now it executes the pcscd process under privileges of nobody/pcscd, rather than root, tightening security a little bit. More importantly, thanks to the fact that USB decices (and other hotpluggable devices) are handled through udev permissions, I’ve also created an extra rules file that hotplugs the service if a new device is added to the pcscd group, which gives a slightly better usability to Gentoo than before.

Unfortunately, this complicates the matter further, as versions of ccid and pcsc-lite need to go hand in hand, stabling them is a PITA; the fact that ifd-gempc is also not fixed yet really don’t make it any nicer. On the other hand, the presence of this now Gentoo-specific hotplug path through UDEV also mean that we could finally drop the HAL support in this ebuild, as that was supposed to provide the generic hotplug mean before.

I hope this situation will turn out good for everybody; if anything seems to be amiss, don’t hesitate to open a bug or tell me directly, and I’ll look into it.

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