Re: [V4] libselinux: drop dso.h

From: William Roberts <bill.c.roberts@gmail.com>
To: Stephen Smalley <stephen.smalley.work@gmail.com>
Cc: Petr Lautrbach <plautrba@redhat.com>,
	Nicolas Iooss <nicolas.iooss@m4x.org>,
	Ulrich Drepper <drepper@redhat.com>,
	Ondrej Mosnacek <omosnace@redhat.com>,
	SElinux list <selinux@vger.kernel.org>,
	William Roberts <william.c.roberts@intel.com>
Subject: Re: [V4] libselinux: drop dso.h
Date: Thu, 12 Mar 2020 09:05:44 -0500	[thread overview]
Message-ID: <CAFftDdpQ2LFifgD4j=usv8WUpN1=xV2S_aOQcbN+MFomYQGrYg@mail.gmail.com> (raw)
In-Reply-To: <CAEjxPJ7wqdhF5G_2n1EsGjuvHdZhLG6Ww4dEkZ+HJjbffFjDVA@mail.gmail.com>

On Wed, Mar 11, 2020 at 1:14 PM Stephen Smalley
<stephen.smalley.work@gmail.com> wrote:
>
> On Thu, Mar 5, 2020 at 2:09 PM William Roberts <bill.c.roberts@gmail.com> wrote:
> >
> > On Thu, Mar 5, 2020 at 10:12 AM William Roberts
> > <bill.c.roberts@gmail.com> wrote:
> > >
> > > On Thu, Mar 5, 2020 at 6:42 AM Petr Lautrbach <plautrba@redhat.com> wrote:
> > > >
> > > >
> > > > Stephen Smalley <stephen.smalley.work@gmail.com> writes:
> > > >
> > > > > On Mon, Mar 2, 2020 at 11:41 AM <bill.c.roberts@gmail.com> wrote:
> > > > >> [PATCH v4 1/4] dso: drop hidden_proto and hidden_def
> > > > >> [PATCH v4 2/4] Makefile: add -fno-semantic-interposition
> > > > >> [PATCH v4 3/4] Makefile: add linker script to minimize exports
> > > > >> [PATCH v4 4/4] libselinux: drop symbols from map
> > > > >
> > > > > This looks fine to me but I'd like at least one of the distro
> > > > > maintainers to ack it (especially the last one).
> > > >
> > > > Acked-by: Petr Lautrbach <plautrba@redhat.com>
> > > >
> > >
> > > Thanks staged:
> > > https://github.com/SELinuxProject/selinux/pull/205
> >
> > merged.
>
> I've noticed a change since this was applied; if I build userspace
> against the updated libselinux, the dynamic loader will
> print a warning if it is run on a system with the older libselinux, ala:
> $ /sbin/restorecon -v /etc
> /sbin/restorecon: /lib64/libselinux.so.1: no version information
> available (required by /sbin/restorecon)
> It still works since there was no real change in the ABI but I don't
> know if this is a concern for distros.

I replicated this and looked into it, AFAICT its relatively harmless since,
as you point out, we're not breaking ABI.

But If I understand your comment (paraphrasing), "userspace should all
be updated together"
from:
  - https://lore.kernel.org/selinux/CAEjxPJ4UPBWSP0E4pjR+F6uKMZNHK9J7LTL1gVznpwyJh9UWNA@mail.gmail.com/

Then it really shouldn't be an issue.

A lot of what I read on the version stuff was written by Urlich, so he
might weigh in with more
information and perhaps a way to correct this.