[RndTbl] "washing" a fork/exec to force all groups

Kevin McGregor kevin.a.mcgregor at gmail.com
Tue Apr 18 09:47:29 CDT 2023


Very minor note: I just created a new user (via useradd) on Solaris 11.4.53
and the default group is "staff" (uid=10).

On Tue, Apr 18, 2023 at 8:19 AM Adam Thompson <athompso at athompso.net> wrote:

> > modern practice of infantilizing the user ("they are too stupid to not
> > shoot themselves in the foot");
>
> I mean... that is fact true across the entire IT space.  The more people
> there are in IS/IT and adjacent fields, the more idiots there are who are
> happily grabbing loaded footguns, aiming them in the traditional manner,
> duct taping it all together and proudly calling it a "production system"
> because they don't know any better.
>
> I don't think the average user is too stupid to not shoot themselves in
> the foot - I think the average IT "professional" is too stupid to not shoot
> themselves in the foot, based on observed evidence.  Present company
> included, from time to time.  It's a variation on the Dunning-Krueger
> effect: we don't know enough about how deep the skills go in some area that
> isn't our primary skillset, so we lash together something that looks good
> but actually makes nearly every possible domain-specific naïve mistake, and
> we don't know the difference precisely because we're not experts in some
> field that doesn't obviously scream "this is really really hard".  (SMTP
> email address validation, anyone?  Did you know you can legally put spaces
> in the middle of an address, for example?)
>
>
> > Haha, we always have this discussion.  I use procmail for the same
> > reason I use sendmail: it's in the repos, the install isn't telling me
> > it's deprecated, I know it intimately, have many installs/configs in
> > place using it, and it works great. Do you have any idea how much time
> > I've saved in my life by not jumping into the "latest thing" daemon
> > just because?
>
> I'm far too old and tired to jump on the "latest hotness" bandwagon.  But
> in this case, I've seen multiple MTA maintainers (I think I'm now up to...
> 5?) explicitly say "don't use procmail, it's unsafe".  I'm assuming this
> many specialists from this many different origins know something I don't.
> And you'll notice ESR has wholly abandoned it - whether due to
> feature-completeness, unmaintainability, or general douchebagginess, I
> can't say.
>
>
> > (And now I can safely say after having to replicate a sendmail setup in
> > postfix that postfix is just as insane, messy and illogical to
> > configure as sendmail!)
>
> In the modern era, I sadly agree.  Enter OpenSMTPd, which is rapidly
> growing enough features and corner cases to make it just as bad.  I think
> this just proves that SMTP should be taken out back and put out of its
> misery, but I don't expect to see that happen in my lifetime.  For better
> and/or for worse.
>
>
> > Postsendfixmail-ng and just skip straight to that.  :-)
>
> LOL.  Sendmail, Postfix, Exim, OpenSMTPd.  Are there any other "major"
> (unix) MTAs left out there?  Should I still have Exim in the list, even?
>
>
> > I'll look into SIEVE.  However, this particular use case is to run a
> > bot-ish thing on the email address.  If SIEVE is some sort of client-y
> > thing then I'm just adding an extra layer (dovecot) for no reason.
>
> It's designed to do all the filtering things that a normal procmail user
> would be using it for.  Probably not going to help you much.  Ofc I still
> don't understand why you need procmail at all, when aliases(5) supports
> pipes directly.
>
> Another option could be running your own (e.g.) Perl single-purpose MTA on
> another port; you already alluded to Postfix being the 2nd MTA on the
> system, do you need all of it, or it is just to support a single
> userid-to-pipe?  https://metacpan.org/pod/Net::SMTP::Server   Warning:
> take note of the author's handle before using...  There are quite a few
> other SMTP servers in CPAN.  I don't see any native PHP servers,
> surprisingly but thankfully.
>
>
> > I do have root, but I wanted a "better" answer that doesn't involve
> > root to update the stackoverflow with a "real" answer.
>
> Sometimes you just need root.  Needing root doesn't make the answer less
> "real".
>
>
> > That's a decent idea.  However, I'm always a bit freaked out making a
> > user's primary group something other than their eponymous group.  Not
> > sure if that's justified or not, but it gives me the heebie-jeebies
> > like I'm breaking some cardinal rule and K&R will come to my house and
> > beat me up.
>
> It's not justified.  Each user having their own primary group is a
> Linuxism, and a fairly recent development in UNIX history.  On Solaris,
> when you create a new user, IIRC their default/primary group is still
> "usr".  Because each user having their own group makes the average system
> much more secure (see "shoot self in foot", above), pretty much everyone
> has adopted it by now.
>
>
> > In my case the program lies in a super complex tree into a git
> > repository of php with strange group structure designed to eliminate the
> > need for world read on the php files themselves.  Changing that
> > structure would be impossible in this case.  But changing the primary
> > group would work, with probably the only downside being any logs the
> > program makes would be group-permed as the "new" primary group.
>
> What about just checking out the git repo, then?  Not to mention: how the
> heck are you getting git to reliably deal with userids and groups?  That's
> very explicitly *not* something git cares about.
>
> -Adam
>
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