[OE-core] [oe] Using libpam with systemd but without systemd-logind

[Richard Purdie]

On Sat, 2018-10-27 at 10:36 +0000, Peter Kjellerstedt wrote:
> 
> > Our embedded system uses systemd and libpam, but doesn't use
> > systemd's logind package.
> > 
> > The libpam recipe,
> > 
https://github.com/openembedded/openembedded-core/blob/master/meta/recipes-extended/pam/libpam_1.3.0.bb#L149
> > ,
> > will add pam_systemd.so to common-session if it detects systemd is
> > used.
> > 
> > However, systemd will only even build pam_systemd.so if the logind
> > package is enabled, shown here:
> > 
https://github.com/systemd/systemd/blob/15b1180945f2cfa0f7938626ff060c8b52606a1a/meson.build#L1747
> > 
> > So in our case, since we are explicitly disabling logind, pam will
> > complain in the journal about not being able to find
> > pam_systemd.so.
> > 
> > As logind isn't a systemd distro feature, I'm not sure how libpam
> > can
> > really know that it doesn't need to add pam_systemd.so to common-
> > session?
> > 
> > Does anyone have any ideas on ways to handle this?
> 
> I am by no means any PAM expert, but prefixing the line inserted
> into 
> /etc/pam.d/common-session with a '-' should make libpam not output 
> anything to the logs if pam_systemd.so does not exist.

The best way I can think of is if each recipe have their own
PACKAGECONFIG entries as appropriate and then your distro configures
both recipes to do the right thing?

Cheers,

Richard