[Freeipa-devel] [PATCH 0002] Port from python-krbV to python-gssapi

[Jan Cholasta]

On 25.8.2015 21:00, Simo Sorce wrote:
> On Tue, 2015-08-25 at 20:45 +0200, Michael Šimáček wrote:
>>
>> On 2015-08-25 18:43, Robbie Harwood wrote:
>>> Jan Cholasta <jcholast at redhat.com> writes:
>>>
>>>> On 25.8.2015 12:46, Michael Šimáček wrote:
>>>>> On 2015-08-25 12:38, Alexander Bokovoy wrote:
>>>>>> On Tue, 25 Aug 2015, Michael Šimáček wrote:
>>>>>>> On 2015-08-24 20:29, Robbie Harwood wrote:
>>>>>>>> Michael Šimáček <msimacek at redhat.com> writes:
>>>>>>>>> On 2015-08-24 17:49, Simo Sorce wrote:
>>>>>>>>>> On Mon, 2015-08-24 at 17:18 +0200, Michael Šimáček wrote:
>>>>>>>>>>> On 2015-08-24 14:50, Jan Cholasta wrote:
>>>>>>>>>>>
>>>>>>>>>>> Fixed. python-gssapi has a display_as method that could pull the
>>>>>>>>>>> name
>>>>>>>>>>> from it, but it doesn't work in current version, therefore using
>>>>>>>>>>> partition to split on '@'
>>>>>>>>
>>>>>>>> It's actually a bug in MIT Krb5, as we noted in your bug[0].  So this:
>>>>>>>>
>>>>>>>>> -        user = api.Command.user_show(unicode(principal[0]))['result']
>>>>>>>>> +        user =
>>>>>>>>> api.Command.user_show(principal.partition('@')[0])['result']
>>>>>>>>
>>>>>>>> is working around a bug in specific Kerberos versions.  If people are
>>>>>>>> okay with merging such code, then I guess this is fine; I would
>>>>>>>> personally not do so because there is not a clear point at which it can
>>>>>>>> be removed.  At the very least, we should wait until we see what
>>>>>>>> versions of krb5 MIT is going to fix.
>>>>>>>>
>>>>>>>> Otherwise, looks good.
>>>>>>>>
>>>>>>>> [0]: https://github.com/pythongssapi/python-gssapi/issues/79
>>>>>>>>
>>>>>>>
>>>>>>> python-krbV migration is blocking support for Python 3. The bug
>>>>>>> doesn't have any fix upstream yet and there are two bugs actually, the
>>>>>>> second one is in python-gssapi, which I've just reported [1]. Waiting
>>>>>>> for two bugs to be fixed could be detrimental to py3 migration as we
>>>>>>> don't have much time left. And I'm no longer sure that display_as
>>>>>>
>>>>>> I don't buy this.
>>>>>>
>>>>>> We have plenty of time for solving these bugs. Remember, that Samba
>>>>>> DCE RPC bindings aren't migrated to Python 3 either and will not be
>>>>>> before release of Samba 4.4. For Samba 4.3 it is simply too late.
>>>>>>
>>>>>> So we are still far away from full Python3 migration for FreeIPA and
>>>>>> waiting for solving these two bugs is OK.
>>>>>
>>>>> If fixing them solves anything at all. I planned to use
>>>>> display_as(NameType.user), but when trying it on Name object with
>>>>> name_type set (which doesn't trigger the segfault), it doesn't seem to
>>>>> work either. I get:
>>>>> gssapi.raw.exceptions.OperationUnavailableError: Major (1048576): The
>>>>> operation or option is not available or unsupported, Minor (0): Unknown
>>>>> error
>>>>>
>>>>> Robbie, can you clarify whether display_as could be actually used to get
>>>>> the first component of the principal reliably?
>>>
>>> display_as should behave in accordance with its docs; anything else is a
>>> bug report, which you filed.  I don't know what you're asking me for
>>> beyond that.
>>>
>>
>> Why I mentioned display_as at all is that I initially assumed it could
>> be used for this, but it was only an assumption because I couldn't get
>> around the segfault. Later on, the cause of the segfault was found and I
>> was able to try the method and I found out that it probably cannot be
>> used for this purpose (i. e. extracting the first component of the
>> principal) regardless of the two bugs. How I thought it would be used:
>> import gssapi
>> cred = gssapi.Credentials()
>> user = cred.name.display_as(gssapi.NameType.user)
>>
>> What I got:
>> gssapi.raw.exceptions.OperationUnavailableError: Major (1048576): The
>> operation or option is not available or unsupported, Minor (0): Unknown
>> error
>>
>> This seems more like the method is not intended to be used this way. So
>> I'm asking you whether it is a bug or whether there is another way to do
>> it. Otherwise display_as cannot be used here.
>>
>>>> As I have written in the other thread, we use "principal.split('@')" in
>>>> other parts of IPA, so "principal.partition('@')" should be OK as well.
>>>>
>>>> This patch works for me, so ACK.
>>>>
>>>> Unless there are any further objections, I would like to push it.
>>>
>>> I think the newest iteration of this
>>>
>>>> user = api.Command.user_show(principal.partition('@')[0].partition('/')[0])['result']
>>>
>>> is even worse, but if it is decided to merge, then hopefully we can be
>>> rid of it quickly.
>>
>> It is splitting a string of known format in a way that is used in other
>> places of freeipa. What is specifically so bad about it? What do you
>> suggest as an alternative?
>
> Given display_as() currently does not work for you go ahead with this
> code. We'll revisit display_as later once we figure out more about the
> bug that makes it fail.

OK.

Pushed to master: aad73fad601f576dd83b758f4448839b4e8e87df

-- 
Jan Cholasta