Bug#994006: libc6: NSS modules changes require a restart of systemd-logind, which is not possible
On 2021-09-14 08:56, Simon McVittie wrote:
> On Mon, 13 Sep 2021 at 22:59:32 +0200, Aurelien Jarno wrote:
> > - running the operation on a non-existing user, but as loginctl does a
> > check that the user exists, it has to be done directly with the dbus
> > API, for instance "gdbus call --system --dest org.freedesktop.login1
> > --object-path /org/freedesktop/login1 --method
> > org.freedesktop.login1.Manager.SetUserLinger 12345678 true true"
> >
> > The latest is more a bit more complex to do (especially that
> > libglib2.0-bin is not necessarily installed on the system), but has the
> > advantage of exercising all configured NSS modules.
>
> systemd happens to have its own D-Bus implementation sd-bus (a competitor
> to libdbus and GLib's GDBus) for which it provides busctl(1), an
> equivalent of gdbus(1) and dbus-send(1). So this could be written as:
>
> busctl call --system org.freedesktop.login1 /org/freedesktop/login1 \
> org.freedesktop.login1.Manager SetUserLinger ubb $uid true true
>
> which does not have dependencies outside systemd.deb.
Thanks a lot for the help here, as my knowledge with systemd is
relatively limited. That seems to work fine when executed just before
the libc6 upgrade in the script I use to trigger the upgrade at boot
time. I'll try to insert all pieces into libc6.preinst and see if that
still works.
> The nonexistent uid should probably be in one of the ranges reserved by
> Policy §9.2.2: perhaps 4294967294 or (uint32_t) -2, which is reserved
> as a representation of the anonymous NFS user?
Yes, that is probably a good pick. I guess we should actually disable
lingering (so ... ubb 4294967294 false false) to minimize the damages if
this user exists anyway.
Regards
Aurelien
--
Aurelien Jarno GPG: 4096R/1DDD8C9B
aurelien@aurel32.net http://www.aurel32.net
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