Bug#868269: Regression from jessie to stretch in handling of %u, %U, %s, and %h

[Josh Triplett]

On Fri, Nov 16, 2018 at 12:55:21AM +0100, Michael Biebl wrote:
> On Sat, 9 Sep 2017 17:18:35 -0700 Josh Triplett <josh at joshtriplett.org>
> wrote:
> > On Sun, Sep 10, 2017 at 01:43:09AM +0200, Michael Biebl wrote:
> > > On Thu, 13 Jul 2017 15:09:29 -0700 Josh Triplett <josh at joshtriplett.org>
> > > wrote:
> > > > Package: systemd
> > > > Version: 233-10
> > > > Severity: normal
> > > > 
> > > > I'm not suggesting a change here, but I do think this could use
> > > > documentation in the release notes and NEWS.Debian file.
> > > > 
> > > > Commit 79413b673b45adc98dfeaec882bbdda2343cb2f9 in systemd 228 (between
> > > > jessie and stretch) effectively broke/disabled the %u, %U, %s and %h
> > > > specifiers in units.  I ran into this with a local unit that used %u,
> > > > which went from expanding to the value of User to expanding to "root".
> > > > It took quite a bit of investigating to figure out the cause.
> > > > 
> > > > At a minimum, I would suggest adding something to the stretch release
> > > > notes about this, as well as a NEWS.Debian entry.
> > > > 
> > > > You might also consider, in your next stretch-proposed-updates upload,
> > > > including the same NEWS.Debian entry.
> > > 
> > > While I'm a bit wary of the inflationary use of NEWS.Debian, I'd be ok
> > > with adding a NEWS entry if one was provided in this case.
> > > Josh, would you be willing to write such a text?
> > 
> > Sure. How does this look?
> > 
> > systemd 228 changed the behavior of the %u, %U, %s, and %h specifiers.
> > They were previously documented as returning the user name, numeric user
> > ID, shell, and home directory of the user configured to run a unit.
> > However, PID 1 cannot safely perform lookups in the username database,
> > due to NSS; thus, these directives already did not work consistently for
> > non-root users. In particular, %u and %U would only resolve whichever of
> > a name or UID was configured via the User= directive.
> > 
> > In systemd 228 and later, these directives always return the information
> > for the user running systemd (root for the system instance), not the
> > unit's configured user. Units shipped by Debian do not use these
> > directives. Please update any local units that use these directives.
> > 
> > For instanced units that use the instance name as the user, substitute
> > that instance name for %u. For other units, substitute the appropriate
> > information directly, or run a script at launch time that looks up the
> > desired information.
> 
> Hm, just to clarify, are you suggesting this should be documented in the
> buster release notes?
> I somehow feel that we missed the boat here and given that we didn't
> really have any bug reports regarding this issue, I'm not sure if it's
> worth mentioning as promimently as in NEWS.Debian.

I was originally suggesting a NEWS.Debian entry, yes. And you had *one*
bug report. ;)

This was a painful debugging adventure, but it's done now. I don't know
whether anyone else will go through that or not; certainly it would only
occur with a locally created systemd service.

This doesn't seem especially worth putting into buster release notes.