Kurt@OpenLDAP.org wrote:
On Apr 8, 2010, at 8:08 PM, Howard Chu wrote:
Kurt@OpenLDAP.org wrote:
On Apr 8, 2010, at 3:58 PM, hyc@symas.com wrote: =20
Sounds like your servers are mis-configured, it is not legal to send =
a=3D20=3D
=20
referral in response to a Bind request.
=20 I note that the technical specification doesn't actually preclude =
return =3D
of a referral in response to a Bind request. However, in practice, =
such =3D
return is quite problematic due to ambiguous semantics and security =3D=
considerations.
=20 Right. I can't find the discussion we had about this back in 2004, but =
certainly we've already hashed this out in great detail before.
=20 The fact is that acting on a referral simply means performing a Bind =
against some other server.
It does nothing for the authentication state of the session on the =
original server.
Right, by returning a referral, regardless of how far the client got in = authentication process (including completion of all challenges), the = client is now anonymous at the original server.
And there's a security concern, the referral information is not = protected by the underlying authentication mechanism. It is actually = quite possible that this be used by an attacker to cause the client to = try authentication multiple times, possibly with chosen plaintext.
I recommend that the library never chase bind referrals.
Agreed. Patched in HEAD.
(I tend to = think of rebind as a misfeature. Robust clients really should be using = the async API and carefully managing security contexts and chasing.)
-
hyc＠symas.com