[Freeipa-devel] [PATCH] #1881 client install when anonymous access is prevented

[Simo Sorce]

On Thu, 2011-09-29 at 10:15 -0600, Rich Megginson wrote:
> On 09/29/2011 10:11 AM, Simo Sorce wrote:
> > On Thu, 2011-09-29 at 17:56 +0200, Martin Kosek wrote:
> >> On Thu, 2011-09-29 at 11:44 -0400, Simo Sorce wrote:
> >>> On Thu, 2011-09-29 at 17:41 +0200, Martin Kosek wrote:
> >>>> On Wed, 2011-09-28 at 18:43 -0400, Simo Sorce wrote:
> >>>>> This patch allows ipa-client-install to successfully complete if
> >>>>> anonymous access is not allowed on the LDAP server.
> >>>>>
> >>>>> I have tested this by changing the value of
> >>>>> nsslapd-allow-anonymous-access from 'on' to 'rootdse' in cn=config
> >>>>> See NOTE about this option.
> >>>>>
> >>>>> This patch warns the user that full verification of the LDAP server was
> >>>>> not possible and may even assume realm is domain.upper() if DNS
> >>>>> discovery is not possible.
> >>>>>
> >>>>> With these caveats the installation on a DNS compliant domain works fine
> >>>>> against a IPA server with anonynous access to LDAP disabled with this
> >>>>> patch.
> >>>>>
> >>>>> Fixes #1881
> >>>>>
> >>>>> Simo.
> >>>>>
> >>>>>
> >>>>> NOTE: Setting rootdse nsslapd-allow-anonymous-access is standards
> >>>>> compliant as it still allows access anonymously to the rootdse entry.
> >>>>> Setting this option to 'off' prevents access even to rootdse and is not
> >>>>> a good idea (the client doesn't know what auth methods are avilable to
> >>>>> authenticate w/o access to rootdse)
> >>>> NACK. The approach looks good, but I found several errors:
> >>>>
> >>>> 1) IPA discovery for servers with anonymous access _allowed_ is broken
> >>>> because of the following lines:
> >>>>
> >>>>
> >>>> +        if ldapret[0] == 0:
> >>>> +            self.server = ldapret[0]<<<  This should be ldapret[1]
> >>>> +            self.realm = ldapret[1]<<<<  This should be ldapret[2]
> >>>> ...
> >>> Ouch I swear I was sure I changed those lines ...
> >>>
> >>>> @@ -259,24 +268,29 @@ class IPADiscovery:
> >>>>                       if trealm == r:
> >>>>                           return [thost, trealm]<<<<<  This should be [0, thost, trealm]
> >>>>                   # must match or something is very wrong
> >>>> -                return []
> >>>> +                return [REALM_NOT_FOUND]
> >>>>
> >>>>
> >>>> 2) If anonymous access is forbidden, IPA base DN cannot be searched
> >>>> since we can't read it's contents and check that it belongs to IPA. If
> >>>> you apply my patch 130, you will see this error:
> >>>>
> >>>> # ipa-client-install --server vm-103.idm.lab.bos.redhat.com --domain idm.lab.bos.redhat.com -p admin -w kokos123
> >>>> Warning: Anonymous access to the LDAP server is disabled.
> >>>> Proceeding without strict verification.
> >>>> Note: This is not an error if anonymous access has been explicitly restricted.
> >>>> DNS domain '' is not configured for automatic KDC address lookup.
> >>>> KDC address will be set to fixed value.
> >>>>
> >>>> Discovery was successful!
> >>>> Hostname: vm-050.idm.lab.bos.redhat.com
> >>>> Realm:
> >>>> DNS Domain: idm.lab.bos.redhat.com
> >>>> IPA Server: vm-103.idm.lab.bos.redhat.com
> >>>> Traceback (most recent call last):
> >>>>    File "/usr/sbin/ipa-client-install", line 1148, in<module>
> >>>>      sys.exit(main())
> >>>>    File "/usr/sbin/ipa-client-install", line 1137, in main
> >>>>      rval = install(options, env, fstore, statestore)
> >>>>    File "/usr/sbin/ipa-client-install", line 866, in install
> >>>>      print "BaseDN: "+cli_basedn
> >>>> TypeError: cannot concatenate 'str' and 'NoneType' objects
> >>>>
> >>>>
> >>>> We will have to add user a possibility to pass base DN for IPA since we
> >>>> cannot check it ourselves. Something like --basedn=BASEDN. I can do it
> >>>> in a scope of my patch after you fix 1) if you don't feel comfortable
> >>>> hacking ipa-client-install.
> >>> The basedn comes from rootdse, that one can be searched. (if you set the
> >>> option in DS to off and din't read my note, you got what you deserve :-)
> >>>
> >>> Simo.
> >>>
> >> I read every word of it :-) My point was that you can have more
> >> databases (basedns, suffixes) configured on the server and when the
> >> anonymous access is disabled we cannot check which one is for IPA.
> >> That's what my patch 130 fixes. Before it, we just took the first
> >> suffix.
> > Ok, in that case we can compare the suffix with the realm.
> > It is 100% guaranteed that suffix and realm must match as we create the
> > suffix out of the realm.
> > Can you add code to check against REALM if anonymous is turned on ?
> >
> > In case REALM is missing (DNS discovery failed) we have 2 options, use
> > domain.upper() or require a --relam= option to be passed by the user,
> > what do you think ?
> >
> > We should really add a defaultNamingContext field in rootdse, maybe we
> > should open a ticket about that so we do not have to dance around this
> > issue ?
> We probably should do this anyway - note that openldap (and AD too?) 
> support publishing the default naming context in the root DSE.
> But you'll still need a way to discover this in older servers.

Yes we can have fallbacks for older servers (the current code).
But having it will makes life easier.
Do you need a bugzilla ?

Simo.

-- 
Simo Sorce * Red Hat, Inc * New York