systemd lsb-base integration script leaking shell variable changes which can break consumers

[Ryan]

I am using systemd version 248.3-1ubuntu3 from the impish repository.

It was compiled and built in the following manner:
# add impish deb-src repository to apt sources
apt build-dep systemd/impish
apt source -b systemd/impish

Once built, it was installed over the top of systemd 245.4-4ubuntu3.

I am running ubuntu 20.04.2.

The source tarball of systemd includes a file (./debian/systemd/lib/lsb/init-functions.d/40-systemd) which is intended to be installed into the drop-in script directory provided by the lsb-base package (/lib/lsb/init-functions.d).

The problem that I am having is that this file (which is sourced by any script which sources /lib/lsb/init-functions) is setting variables, and in doing so, accidentally overwriting variables which are configured by the calling script.

https://gist.github.com/TheWug/e120145f08e994d89e235e077a82ea75#file-40-systemd-L19

I noticed this when investigating why ipmiutil_wdt.service (provided by package ipmiutil) was failing to start. The problem is that the ipmiutil_wdt script, which makes use of init-functions, was statically setting some variables for later use, including one called $prog. $prog is then inadvertently overwritten by 40-systemd when ipmiutil_wdt sources /lib/lsb/init-functions.

I think this is systemd's bug because systemd's lsb-base drop-in is not being a "good neighbor" to the scripts with which it shares a controlling shell. Even if ipmiutil were to rewrite its ipmiutil-wdt script, any other such script provided by another package which tries to use a variable called $prog (or $executable, or $argument, or $service, or $state, or any of a handful of others) will find its feet being stepped on by systemd's drop-in.

I propose that the drop-in be modified to encapsulate all of this behavior where variables are assigned to within a function or subshell or something, so they can't accidentally contaminate the outside world.

Other related package versions:
lsb-base: 11.1.0ubuntu2
ipmiutil: 3.1.5-1

[Ryan (wug)]

I'm not a bash script architect, but I bodged together this workaround and the ipmiutil_wdt service starts correctly with it applied to my system:

https://gist.github.com/TheWug/1a7f509e040f10c05039acc06fe29d9e

[Ryan (wug)]

It also looks like, farther down, systemctl_redirect() leaks $service. Not sure if it's intentional or not, given that it works to protect its other variables, so maybe it could use some attention too.

https://gist.github.com/TheWug/e120145f08e994d89e235e077a82ea75#file-40-systemd-L70

[Nick Rosbrook (enr0n)]

 Is this still relevant?

[Launchpad Janitor (janitor)]

[Expired for systemd (Ubuntu) because there has been no activity for 60 days.]