[Pkg-samba-maint] Bug#726472: share passwords not working after upgrade from samba3

[Ivo De Decker]

Hi,

On Mon, Oct 28, 2013 at 10:00:12PM +0100, Ivo De Decker wrote:
> It is quite possible that the issue is triggered by a race condition in the
> tdb-handling (especially for passdb.tdb), which can result in the creation of
> the wrong tdb file during the upgrade, which messes up our move. This could be
> caused by the usage of the 'smbpasswd' command or the pam-smbpass pam module.
> I haven't had the time yet to create a situation where I can trigger the race
> condition.

I was able to reliably trigger the race condition like this:

- install samba and libpam-smbpass from wheezy or jessie
- dist-upgrade to unstable
- during the dist-upgrade login with ssh (using password authentication) after
  libpam-smbpass has been unpacked, but before the samba postinst runs

At the time of the login, libpam-smbpass will try to update
/var/lib/samba/private/passdb.tdb, which is created because it doesn't exist.
Later, the samba postinst will fail, because both
/var/lib/samba/private/passdb.tdb and /var/lib/samba/passdb.tdb exist. With
earlier versions, the postinst didn't fail, but just kept the new (almost
empty) /var/lib/samba/private/passdb.tdb.


Cheers,

Ivo