[Freeipa-devel] [PATCH] 0207, 0218-0219 Solving trust conflicts and external trust topology fixes

Wed Aug 17 11:16:15 UTC 2016

On 08/17/2016 12:41 PM, Alexander Bokovoy wrote:
> On Wed, 17 Aug 2016, Martin Babinsky wrote:
>> On 08/15/2016 06:06 PM, Alexander Bokovoy wrote:
>>> On Mon, 15 Aug 2016, Alexander Bokovoy wrote:
>>>> Hi!
>>>>
>>>> Attached are trust-related patches.
>>>>
>>>> 0207 is a pre-requisite. I did send it before, it is re-formatting of
>>>> the ipaserver/dcerpc.py to be close to PEP8 requirements.
>>>>
>>>> 0218 is an automated trust topology conflict resolver for DNS namespace
>>>> conflicts. Read the commit message for details, and also comments in
>>>> the
>>>> code. With this patch FreeIPA becomes more smart than Windows Server
>>>> which doesn't have automated trust topology conflict resolution. ;)
>>>>
>>>> 0219 fixes issue of topology details leaking through external trust.
>>>> The
>>>> problem is only in presentation as we store more data than needed -- it
>>>> is impossible to cross external trust boundary anyway as it is handled
>>>> by AD DC side, but one important consequence is that we need to store
>>>> UPN suffixes before we start storing information about child domains.
>>>> Again, read the commit message.
>>>>
>>>> These patches also are on top of my previously sent patches 0215-0216.
>>> Patches attached.
>>>
>>>
>>>
>>
>> Hi Alexander,
>>
>> patch 207: LGTM, but I have a feeling that the patch should be linked
>> to both #6021 and #6076 so that it is not lost during backports.
>>
>> patch 218:
>>
>> ipalib/errors.py:
>>
>> 1.)
>> I'm not sure if TrustTopologyConflictError should inherit from
>> InvocationError. The semantics of InvocationError implies that
>> something was wrong when trying to invoke the command (a param failed
>> to validate/convert, incorrect number of args, etc.), while this is
>> more of an exception during command execution (no. and type of params
>> was correct, command started to execute but encountered an error
>> condition). Thus I think it should inherit from ExecutionError. CC'ing
>> Jan for more thoughts on this.
>>
>> 2.)
>>
>> Why is TrustTopologyConflictSolved listed amogn public errors? Since
>> it is used only in dcerpc.py to restart trust establishment after
>> resolving conflicts, it should be a private exception in dcerpc.py for
>> this purpose.
>>
>> 3.)
>> Also please split the exception format string like this so that the
>> line is not too long (there is not much we can do about doctest so
>> leave that line as it is):
>>
>> @@ -882,7 +882,8 @@ class TrustTopologyConflictError(InvocationError):
>>     """
>>
>>     errno = 3017
>> -    format = _("Forest '%(forest)s' has existing trust to forest(s)
>> %(domains)s which prevents a trust to '%(conflict)s'")
>> +    format = _("Forest '%(forest)s' has existing trust to forest(s) "
>> +               "%(domains)s which prevents a trust to '%(conflict)s'")
>>
>> Do not worry about gettext, it can handle it just fine, there are
>> plenty of examples in server plugins, for example.
>>
>>
>> ipaserver/dcerpc.py:
>>
>> 1.)
>>
>> I think that instead of returning result and raising
>> TrustTopologyConflictError based on that, the 'clear_ftinfo_conflict'
>> can raise this exception directly. You can have an empty list defined
>> at the beginning instead of 'result list', append unresolvable
>> conflicts to it and then at the end of the method check if it is
>> non-empty and raise the exception.
>>
>> 2.)
>>
>> +        # In the code below:
>> +        # self -- the forest we establish trust to
>> +        # another_domain -- a forest that establishes trust to 'self'
>> +        # cinfo -- lsa_ForestTrustCollisionInfo structure that contain
>> +        #          set of of lsa_ForestTrustCollisionRecord structures
>> I would add this directly into the method docstring:
>>
>> """
>> ...
>>
>> :param self: the forest we establish trust to
>> :param another_domain: a forest that establishes trust to 'self'
>> :param cinfo: lsa_ForestTrustCollisionInfo structure that contain
>>           set of of lsa_ForestTrustCollisionRecord structures
>> """
>>
>> Additionally, the behavior specifed in previous comment can be added
>> using :raises: stanza:
>>
>> """
>> :raises: errors.TrustTopologyConflictError if there are unresolvable
>>    namespace conflicts between trusted domains
>> """
>>
>> 3.)
>>
>> rewriting 'clear_ftinfo_conflict' according to point 1.) will allow to
>> simplify code in 'update_ftinfo' like this:
>>
>> """
>> -                res = self.clear_ftinfo_conflict(another_domain, cinfo)
>> -                if len(res[1]) != 0:
>> -                    domains = [x.name.string for x in res[1]]
>> -                    raise errors.TrustTopologyConflictError(
>> -                              target=self.info['dns_domain'],
>> -
>> conflict=another_domain.info['dns_domain'],
>> -                              domains=domains)
>> -                else:
>> -                    raise errors.TrustTopologyConflictSolved(
>> -                              target=self.info['dns_domain'],
>> -
>> conflict=another_domain.info['dns_domain'])
>> +                self.clear_ftinfo_conflict(another_domain, cinfo)
>> +                raise errors.TrustTopologyConflictSolved(
>> +                    target=self.info['dns_domain'],
>> +                    conflict=another_domain.info['dns_domain'])
>> """
>>
>> Patch 218:
>>
>> 1.)
>> typo in the commit message:
>>
>> """
>> ...
>> suffixes are forest-wide, there *are could be* user accounts in the
>> ...
>> """
>>
>> 2.)
>> A stupid question I know, but why do we need to replace empty string
>> with None here?
>>
>> """
>>         # with the forest, thus we have to use
>> netr_DsRGetForestTrustInformation
>> -        domains =
>> netr_pipe.netr_DsRGetForestTrustInformation(td.info['dc'], '', 0)
>> +        domains =
>> netr_pipe.netr_DsRGetForestTrustInformation(td.info['dc'], None, 0)
>> """
> I'm answering this one while working on the other fixes.
>
> netr_DsRGetForestTrustInformation() uses NULL to say a parameter is
> missing, not empty string. It actually causes an issue if we don't do
> that when asking a domain controller from a domain that is not a root
> domain of the forest where we get currently undocumented error
> NERR_ACFNotLoaded (0x000008b3). If non-NULL name is specified, AD domain
> controller will perform proper operation only if it is a domain
> controller from the forest root domain and the domain specified is
> known. Obviously, a domain named '' cannot be known. This breaks
> external trust.
>
> Perhaps, this could be moved into a separate patch on its own.
>

+1 for separate patch, thank you for your explanation.

>>
>> --
>> Martin^3 Babinsky
>


-- 
Martin^3 Babinsky