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Re: masking LDAP_SIZELIMIT_EXCEEDED
Hmm, maybe drawing a parallel to an ACL was a bad idea (although this
behavior does sound similar to "disclose" to me because I want to not
expose the truth to some unprivileged clients). The clients I want to keep
in the dark are due to their code path, not because the information is
something that I want to keep from them for privacy/security per se.
We have entries along the lines of:
This is totally valid in our (feel free to call it warped) view of the
world. person2 is indeed the same physical person, but they only intersect
on "uid" from the directory perspective. Very notably, person2@Org1 and
person2@Org2 have different userPassword attributes.
I'm sure this all sounds slightly ridiculous, but it actually works quite
well. It makes things particularly easy for administrators of systems in
either Org1 or Org2. The exception is on queries that span Org*. We've
seen two basic client behaviors with off-the-shelf software:
1. Search, and use the first candidate entry that's returned. Our users
hae been trained that "Org1" is the most important and they should use
that password/expect those attributes on systems that span units.
2. Search, and error out since multiple candidates are returned.
I don't necessarily think there's anything wrong with (2), but it causes
my example "person2" to not get access. What I'd like is to mimic (1).
I've been patching client software to that behavior, but it seems that
there's a lot of (2) out there. So I'm looking for something server-side
to fix this "permanently". If I set a sizelimit of 1, then only
will be returned on a '(uid=person2)' query. The problem is that the
return code is not LDAP_SUCCESS, so I error out on that issue. If I mask
the exceeded result, then the (2) clients will be blissfully ignorant that
person2 spans multiple entries, and grant access under the Org1 candidate
dn (which is what I want).
On Thu, 8 Mar 2007, Howard Chu wrote:
Aaron Richton wrote:
I've found a situation similar to what I believe inspired "disclose" ACLs,
in which giving out the return value of LDAP_SIZELIMIT_EXCEEDED is telling
clients something that I don't want them to know (i.e. "keep digging.") I'd
like to just throw away the code and change it to LDAP_SUCCESS. Can anybody
think of a way to do this (slapo-retcode comes to mind, but I can't see how
it would work on these very non-dynamic entries) or should I just write an
eight line overlay?
Is this something that enough people want that there should be, say, a
"silent" option to the limits directive?
This seems like a pointless option. If I do a search for (cn>=a) and get 500
entries returned, and another search for (cn>=b) and still get 500 entries
returned, then it's obvious there are more entries out there even if you mask
the result code. The "disclose" feature of ACLs is a real security measure,
because it prevents you from seeing that which you could not see by any
means. What you're proposing here is not; the information you're hiding can
still be discovered by other legitimate mechanisms. It is easily circumvented
and it's contrary to the specification of the Directory System models.
-- Howard Chu
Chief Architect, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc
Chief Architect, OpenLDAP http://www.openldap.org/project/