On 08/30/2012 02:53 PM, Rob Crittenden wrote:
> Martin Kosek wrote:
>> Current objectclass updates in a form of "replace" update instruction
>> dependent on exact match of the old object class specification in the
>> update instruction and the real value in LDAP. However, this approach is
>> very error prone as object class definition can easily differ as for
>> example because of unexpected X-ORIGIN value. Such objectclass update
>> failures may lead to serious malfunctions later.
>>
>> Add new update instruction type "replaceoc" with the following format:
>> replaceoc:OID:new
>> This update instruction will always replace an objectclass with
>> specified OID with the new definition.
>>
>> https://fedorahosted.org/freeipa/ticket/2440
> 
> This works ok. Martin and I had a conversation in IRC about it.
> 
> This moves from replacing a specific bit of schema with a new one, in all
> cases. I wonder if we should be more conservative and know what we're 
> replacing
> in advance.
> 
> rob
> 

You are right, I was too harsh when replacing the objectclasses. This would
cause issues when LDAP update would be run on a replica with lower version and
older objectclass definitions.

I came up with an alternative solution and instead of always replacing the
objectclass I rather reverted to old-OC:new-OC style which should be safer.
Now, the LDAP updater always normalizes an objectclass before comparing it
using python-ldap objectclass model. With this approach, objectclasses
differing only in X-ORIGIN or white spaces should match and be updated.

Martin
>From bc884959bc8429142075d7fc6fd2d95bb2733db6 Mon Sep 17 00:00:00 2001
From: Martin Kosek <mko...@redhat.com>
Date: Tue, 4 Sep 2012 13:18:54 +0200
Subject: [PATCH] Add safe updates for objectClasses

Current objectclass updates in a form of "replace" update instruction
dependent on exact match of the old object class specification in the
update instruction and the real value in LDAP. However, this approach is
very error prone as object class definition can easily differ as for
example because of unexpected X-ORIGIN value. Such objectclass update
failures may lead to serious malfunctions later.

When comparing the objectclasses, make sure we normalize them both
before we compare them to mitigate these kinds of errors. python-ldap's
objectclass model can be utilized to do the normalization part.

One objectclass update instruction was changed to do a replace of
an objectclass separately from add update instruction so that we
really only replace what's stored in LDAP.

https://fedorahosted.org/freeipa/ticket/2440
---
 install/updates/10-bind-schema.update |  2 ++
 ipaserver/install/ldapupdate.py       | 46 ++++++++++++++++++++++++++++++++++-
 2 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/install/updates/10-bind-schema.update b/install/updates/10-bind-schema.update
index 0edbad2046929210e8b88d8232d24b5298912eb5..3c43c8ec79fe6cb9830a27fb2880b6ed0cf0d8e4 100644
--- a/install/updates/10-bind-schema.update
+++ b/install/updates/10-bind-schema.update
@@ -75,4 +75,6 @@ add:objectClasses:
       MUST idnsName
       MAY managedBy
       X-ORIGIN 'IPA v3' )
+
+dn: cn=schema
 replace:objectClasses:( 2.16.840.1.113730.3.8.6.1 NAME 'idnsZone' DESC 'Zone class' SUP idnsRecord STRUCTURAL MUST ( idnsZoneActive $$ idnsSOAmName $$ idnsSOArName $$ idnsSOAserial $$ idnsSOArefresh $$ idnsSOAretry $$ idnsSOAexpire $$ idnsSOAminimum ) MAY idnsUpdatePolicy )::( 2.16.840.1.113730.3.8.6.1 NAME 'idnsZone' DESC 'Zone class' SUP idnsRecord    STRUCTURAL MUST ( idnsName $$ idnsZoneActive $$ idnsSOAmName $$ idnsSOArName $$ idnsSOAserial $$ idnsSOArefresh $$ idnsSOAretry $$ idnsSOAexpire $$ idnsSOAminimum ) MAY ( idnsUpdatePolicy $$ idnsAllowQuery $$ idnsAllowTransfer $$ idnsAllowSyncPTR $$ idnsForwardPolicy $$ idnsForwarders ) )
diff --git a/ipaserver/install/ldapupdate.py b/ipaserver/install/ldapupdate.py
index d673ad57dd4abef68fefb256d933dd6341e6c847..0ee8ec5498c06fbff9188a89336398bb7e2f8f5c 100644
--- a/ipaserver/install/ldapupdate.py
+++ b/ipaserver/install/ldapupdate.py
@@ -35,6 +35,7 @@ from ipalib import errors
 from ipalib import api
 from ipapython.dn import DN
 import ldap
+from ldap.schema.models import ObjectClass
 from ipapython.ipa_log_manager import *
 import krbV
 import platform
@@ -546,6 +547,28 @@ class LDAPUpdate:
                     entry_values = []
                 else:
                     entry_values = [entry_values]
+
+            # Replacing objectClassess needs a special handling and
+            # normalization of OC definitions to avoid update failures for
+            # example when X-ORIGIN is the only difference
+            objectclass_replacement = False
+            if action == "replace" and entry.dn == DN(('cn', 'schema')) and \
+                    attr.lower() == "objectclasses":
+                objectclass_replacement = True
+                oid_index = {}
+                # build the OID index for replacing
+                for objectclass in entry_values:
+                    try:
+                        objectclass_object = ObjectClass(objectclass)
+                    except Exception, e:
+                        self.error('replace: cannot parse ObjectClass "%s": %s',
+                                        objectclass, e)
+                        continue
+                    # In a corner case, there may be more representations of
+                    # the same objectclass due to the previous updates
+                    # We want to replace them all
+                    oid_index.setdefault(objectclass_object.oid, []).append(objectclass)
+
             for update_value in update_values:
                 if action == 'remove':
                     self.debug("remove: '%s' from %s, current value %s", update_value, attr, entry_values)
@@ -601,7 +624,28 @@ class LDAPUpdate:
                     except ValueError:
                         raise BadSyntax, "bad syntax in replace, needs to be in the format old::new in %s" % update_value
                     try:
-                        entry_values.remove(old)
+                        if objectclass_replacement:
+                            try:
+                                objectclass_old = ObjectClass(str(old))
+                            except Exception, e:
+                                self.error('replace: cannot parse replaced ObjectClass "%s": %s',
+                                        old, e)
+                                continue
+                            replaced_values = []
+                            for objectclass in oid_index.get(objectclass_old.oid, []):
+                                objectclass_object = ObjectClass(objectclass)
+                                if str(objectclass_old).lower() == str(objectclass_object).lower():
+                                    # compare normalized values
+                                    replaced_values.append(objectclass)
+                                    self.debug('replace: replace ObjectClass "%s" with "%s"',
+                                            old, new)
+                            if not replaced_values:
+                                self.debug('replace: no match for replaced ObjectClass "%s"', old)
+                                continue
+                            for value in replaced_values:
+                                entry_values.remove(old)
+                        else:
+                            entry_values.remove(old)
                         entry_values.append(new)
                         self.debug('replace: updated value %s', entry_values)
                         entry.setValues(attr, entry_values)
-- 
1.7.11.4

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