[Freeipa-devel] [PATCH 0179] Preserve user principal aliases during rename operation
Martin Babinsky
mbabinsk at redhat.com
Wed Jul 13 14:35:30 UTC 2016
On 07/13/2016 04:28 PM, Simo Sorce wrote:
> On Wed, 2016-07-13 at 16:19 +0200, Martin Babinsky wrote:
>> On 07/13/2016 03:08 PM, Simo Sorce wrote:
>>>
>>> On Wed, 2016-07-13 at 14:37 +0200, Petr Vobornik wrote:
>>>>
>>>> On 07/12/2016 04:19 PM, Simo Sorce wrote:
>>>>>
>>>>>
>>>>> On Tue, 2016-07-12 at 15:46 +0200, Martin Babinsky wrote:
>>>>>>
>>>>>>
>>>>>> On 07/12/2016 02:00 PM, Martin Babinsky wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On 07/12/2016 01:05 PM, Alexander Bokovoy wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On Mon, 11 Jul 2016, Martin Babinsky wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> From 185bde00a76459430d95ff207bf1fb3fe31e811a Mon Sep
>>>>>>>>> 17
>>>>>>>>> 00:00:00 2001
>>>>>>>>> From: Martin Babinsky <mbabinsk at redhat.com>
>>>>>>>>> Date: Fri, 1 Jul 2016 18:09:04 +0200
>>>>>>>>> Subject: [PATCH] Preserve user principal aliases during
>>>>>>>>> rename
>>>>>>>>> operation
>>>>>>>>>
>>>>>>>>> When a MODRDN is performed on the user entry, the
>>>>>>>>> MODRDN
>>>>>>>>> plugin
>>>>>>>>> resets
>>>>>>>>> both
>>>>>>>>> krbPrincipalName and krbCanonicalName to the value
>>>>>>>>> constructed
>>>>>>>>> from
>>>>>>>>> uid. In
>>>>>>>>> doing so, hovewer, any principal aliases added to the
>>>>>>>>> krbPrincipalName
>>>>>>>>> are
>>>>>>>>> wiped clean. In this patch old aliases are fetched
>>>>>>>>> before
>>>>>>>>> the
>>>>>>>>> MODRDN
>>>>>>>>> operation
>>>>>>>>> takes place and inserted back after it is performed.
>>>>>>>>>
>>>>>>>>> This also preserves previous user logins which can be
>>>>>>>>> used
>>>>>>>>> further for
>>>>>>>>> authentication as aliases.
>>>>>>>>>
>>>>>>>>> https://fedorahosted.org/freeipa/ticket/6028
>>>>>>>>> ---
>>>>>>>>> ipaserver/plugins/baseuser.py | 46
>>>>>>>>> +++++++++++++++++++++++++++++++++++++++++++
>>>>>>>>> 1 file changed, 46 insertions(+)
>>>>>>>>>
>>>>>>>>> diff --git a/ipaserver/plugins/baseuser.py
>>>>>>>>> b/ipaserver/plugins/baseuser.py
>>>>>>>>> index
>>>>>>>>> 0052e718afe639bcc1c0a698ded39ea8407a0551..e4288a5a13115
>>>>>>>>> 7815
>>>>>>>>> ffb2
>>>>>>>>> 452692a7edb342f6ac3
>>>>>>>>>
>>>>>>>>> 100644
>>>>>>>>> --- a/ipaserver/plugins/baseuser.py
>>>>>>>>> +++ b/ipaserver/plugins/baseuser.py
>>>>>>>>> @@ -498,6 +498,50 @@ class baseuser_mod(LDAPUpdate):
>>>>>>>>> len =
>>>>>>>>> int(config.get('ipamaxusernamelength')[0])
>>>>>>>>> )
>>>>>>>>> )
>>>>>>>>> +
>>>>>>>>> + def preserve_krbprincipalname_pre(self, ldap,
>>>>>>>>> entry_attrs,
>>>>>>>>> *keys,
>>>>>>>>> **options):
>>>>>>>>> + """
>>>>>>>>> + preserve user principal aliases during rename
>>>>>>>>> operation. This
>>>>>>>>> is the
>>>>>>>>> + pre-callback part of this. Another method
>>>>>>>>> called
>>>>>>>>> during
>>>>>>>>> post-callback
>>>>>>>>> + shall insert the principals back
>>>>>>>>> + """
>>>>>>>>> + if options.get('rename', None) is None:
>>>>>>>>> + return
>>>>>>>>> +
>>>>>>>>> + try:
>>>>>>>>> + old_entry = ldap.get_entry(
>>>>>>>>> + entry_attrs.dn, attrs_list=(
>>>>>>>>> + 'krbprincipalname',
>>>>>>>>> 'krbcanonicalname'))
>>>>>>>>> +
>>>>>>>>> + if 'krbcanonicalname' not in old_entry:
>>>>>>>>> + return
>>>>>>>>> + except errors.NotFound:
>>>>>>>>> + self.obj.handle_not_found(*keys)
>>>>>>>>> +
>>>>>>>>> + self.context.krbprincipalname = old_entry.get(
>>>>>>>>> + 'krbprincipalname', [])
>>>>>>>>> +
>>>>>>>>> + def preserve_krbprincipalname_post(self, ldap,
>>>>>>>>> entry_attrs,
>>>>>>>>> **options):
>>>>>>>>> + """
>>>>>>>>> + Insert the preserved aliases back to the user
>>>>>>>>> entry
>>>>>>>>> during
>>>>>>>>> rename
>>>>>>>>> + operation
>>>>>>>>> + """
>>>>>>>>> + if options.get('rename', None) is None or not
>>>>>>>>> hasattr(
>>>>>>>>> + self.context, 'krbprincipalname'):
>>>>>>>>> + return
>>>>>>>>> +
>>>>>>>>> + obj_pkey =
>>>>>>>>> self.obj.get_primary_key_from_dn(entry_attrs.dn)
>>>>>>>>> + canonical_name =
>>>>>>>>> entry_attrs['krbcanonicalname'][0]
>>>>>>>>> +
>>>>>>>>> + principals_to_add = tuple(p for p in
>>>>>>>>> self.context.krbprincipalname if
>>>>>>>>> + p != canonical_name)
>>>>>>>>> +
>>>>>>>>> + if principals_to_add:
>>>>>>>>> + result =
>>>>>>>>> self.api.Command.user_add_principal(
>>>>>>>>> + obj_pkey, principals_to_add)['result']
>>>>>>>>> +
>>>>>>>>> + entry_attrs['krbprincipalname'] =
>>>>>>>>> result.get('krbprincipalname', [])
>>>>>>>>> +
>>>>>>>>> def check_mail(self, entry_attrs):
>>>>>>>>> if 'mail' in entry_attrs:
>>>>>>>>> entry_attrs['mail'] =
>>>>>>>>> self.obj.normalize_and_validate_email(entry_attrs['mail
>>>>>>>>> '])
>>>>>>>>> @@ -557,9 +601,11 @@ class baseuser_mod(LDAPUpdate):
>>>>>>>>>
>>>>>>>>> self.check_objectclass(ldap, dn, entry_attrs)
>>>>>>>>> self.obj.convert_usercertificate_pre(entry_attr
>>>>>>>>> s)
>>>>>>>>> + self.preserve_krbprincipalname_pre(ldap,
>>>>>>>>> entry_attrs,
>>>>>>>>> *keys,
>>>>>>>>> **options)
>>>>>>>>>
>>>>>>>>> def post_common_callback(self, ldap, dn,
>>>>>>>>> entry_attrs,
>>>>>>>>> *keys,
>>>>>>>>> **options):
>>>>>>>>> assert isinstance(dn, DN)
>>>>>>>>> + self.preserve_krbprincipalname_post(ldap,
>>>>>>>>> entry_attrs,
>>>>>>>>> **options)
>>>>>>>>> if options.get('random', False):
>>>>>>>>> try:
>>>>>>>>> entry_attrs['randompassword'] =
>>>>>>>>> unicode(getattr(context, 'randompassword'))
>>>>>>>>> --
>>>>>>>>> 2.5.5
>>>>>>>>>
>>>>>>>> The approach looks good.
>>>>>>>>
>>>>>>>> For the record, we also support aliases for hosts and
>>>>>>>> service
>>>>>>>> kerberos
>>>>>>>> principals but we don't support rename options for them,
>>>>>>>> so
>>>>>>>> there
>>>>>>>> is no
>>>>>>>> need to add similar logic there.
>>>>>>>>
>>>>>>>>
>>>>>>> That's right, I have updated the corresponding section of
>>>>>>> the
>>>>>>> design
>>>>>>> page [1] for future reference.
>>>>>>>
>>>>>>> [1]
>>>>>>> http://www.freeipa.org/page/V4/Kerberos_principal_aliases#M
>>>>>>> anag
>>>>>>> emen
>>>>>>> t_framework
>>>>>>>
>>>>>>>
>>>>>> Adding Simo to the loop since he is not convinced that this
>>>>>> is
>>>>>> the
>>>>>> right
>>>>>> behavior. As I see it, it seems to not be a security issue
>>>>>> but
>>>>>> more
>>>>>> of a
>>>>>> different expectations about the perceived correct behavior
>>>>>> in
>>>>>> this
>>>>>> particular situation.
>>>>>>
>>>>>> I can see the use case in keeping the old aliases, e.g.
>>>>>> keeping
>>>>>> the
>>>>>> old
>>>>>> credentials after legal name change, but I can also see the
>>>>>> available
>>>>>> space for user principal names piling up and cluttering
>>>>>> quickly
>>>>>> in
>>>>>> large
>>>>>> organizations.
>>>>> after some thinking I think it is ok to keep by default and
>>>>> then
>>>>> drop
>>>>> as it avoid races if you do really want to keep the aliases.
>>>>>
>>>>> However the CLI/UI should probably offer a button/switch to
>>>>> allow
>>>>> to
>>>>> drop all aliases on rename, what it would do would be to modify
>>>>> the
>>>>> entry after the rename and drop the aliases.
>>>>>
>>>>> I am a bit uncertain what to do by default with the "original
>>>>> name".
>>>>> I can see it going both ways on whether to keep it by default
>>>>> or
>>>>> not.
>>>> Ideally we would have e.g.
>>>>
>>>> ipa user-rename oldCN --remove-aliases
>>>>
>>>> which would drop everything including oldCN (I would expect
>>>> that).
>>> I lean toward this conclusion too given that a later "--remove-
>>> alias"
>>> would drop it, and we want to behave consistently.
>>>
>> Makes sense to me, too.
>>
>>>
>>>>
>>>> Unfortunately we have --rename in mod command
>>>> ipa user-mod oldCN --rename newCn --remove-aliases
>>>>
>>>> And there --remove-aliases might not be the best thing.
>>> Why not ?
>>>
>>>>
>>>> Do we want to support also:
>>>> ipa user-mod CN --remove-aliases
>>> Yes we probably want to give the option to drop aliases if an admin
>>> realizes he should have done it at rename time but didn't.
>>>
>>> Simo.
>>>
>> In that case he can still use `user-remove-principal` to manually
>> remove them.
>
> True.
> Should we then not have --remove-aliases at all, and always force the
> admin to manually cleanup ?
>
>
> Simo.
>
I guess that would be the path of least resistance for us. We will
document the change of behavior and leave current API intact for now.
The option can easily be added later if community requests it.
--
Martin^3 Babinsky
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