Re: serious bug in usbguard installation
On 02/04/2017 10:09 PM, Muri Nicanor wrote:
> i just found a bug (#854192) in the installation procedure of usbguard:
> when i install usbguard on a minimal stretch system, the installation
> stalls and never ends successfully. apparently it has something to do
> with dbus being a dependency of usbguard. if i install dbus *before*
> installing usbugard, everything works fine. this is probably, why it
> didn't come up before. if i don't, the installations procedure stalls at
>> /var/lib/dpkg/info/usbguard.postinst configure
>
> and the journal says
>> Feb 04 13:11:04 debian dbus-daemon[1200]: Unknown username
>> "usbguard-dbus" in message bus configuration file
>> Feb 04 13:11:04 debian dbus-daemon[1200]: Failed to start message
>> bus: Could not get UID and GID for username "messagebus"
Problem is that DBus fails to start, and systemd requires DBus to be
running (and configured properly) if Type=dbus is used.
The problem is that your package doesn't have Depends: dbus, so it
doesn't depend on the DBus daemon being available, so APT configures
dbus after usbguard (it's allowed to do that w/o an explicit Depends),
which is bad, since dbus's postinst creates the 'messagebus' user,
without which the DBus daemon doesn't start.
Fix is simple: add that dependency. :-) If you look at other DBus
services, they all have that dependency explicitly.
That said: I just tried this in a VM, and systemd appears to be
quite broken if you try to start a Type=dbus unit when DBus is
installed, but not properly configured. And while that is not
normally the case, I couldn't get systemd to work properly again
without rebooting it, not even a daemon-reexec worked. So I think
this would also qualify as a systemd bug here - it should just
fail the Type=dbus unit at this point, and not go into an endless
loop. I'll report that separately.
Regards,
Christian
Reply to: