On enabling read ACLs on LDAP searches for 4.0

Nadezhda Ivanova nivanova at samba.org
Wed Nov 21 01:34:45 MST 2012

Hi Andrew and Metze,
Does this mean that with Metze's work, the read ACLs no longer break a ton
of tests in make test? If so, that makes me very happy :).
Metze, thank you so much for picking up where I failed to continue!

On Wed, Nov 21, 2012 at 8:44 AM, Andrew Bartlett <abartlet at samba.org> wrote:

> Metze,
> I'm delighted to see the work you have done recently, and incredibly
> pleased to see that we have the chance to protect the data in an AD
> server we are hosting with the read ACLs that the administrator
> specified.
> It is really important that, particularly in a situation where we join
> an existing domain, we can still protect that information as well as a
> Microsoft server would.  This eliminates unexpected surprises that some
> might describe as security holes, and puts into production work a great
> and impressive effort by Nadya.
> As such, I'm really exited by this, and I'm quite keen that our users
> get to have this in Samba 4.0, given the patches are available.
> That said, I'm also cautious - you would of course remember my caution
> around the DNS server change, and this is even more 'last moment' than
> that was.  There are really important issues to consider, such as if we
> break some of the harder to test features (eg, running a wintest to
> verify interactions with Windows), and if we are really delivering what
> we are promising.
> Some specific concerns:
>  - constraints for DB integrity (wouldn't want ACLs to somehow allow
> duplicate user creation because you can't see one!)
>  - while at the same time as avoiding information leaks such as might
> happen if a 'helper' search was substantially controlled by the caller
> was invoke 'AS_SYSTEM' as I understand you do
> My view at RC1 stage (when we first discussed if this blocker bug and
> discussed DNS) was that this would be a 'new feature' and it was too
> late to add it in, but now I'm not so certain, or so black-and-white.
> In short, this isn't 'just another feature'.
> The fact that we got this far without solving another serious ACL issue
> (for GPOs) has rattled my confidence a little, but I'm not sure that
> means we should leave this as a known issue for a whole release cycle.
> My gut feeling is to enable this, audit it carefully (both before and
> after the release), and allow users to turn if off if it causes issues.
> Adding an 'acl:search=false' would get users back to where we are now,
> and is an easily described fallback.  But doing this rests on our
> extensive automated tests (of which I'm very grateful), a similar
> battery of manual tests and a careful review of the code.
> Andrew Bartlett
> --
> Andrew Bartlett                                http://samba.org/~abartlet/
> Authentication Developer, Samba Team           http://samba.org

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