Open Stack

I agree, there are two very different models for getting a third party
to do something for you: delegation oF authority and sub-contracting.
Your examples of the kids at daycare and buying something online neatly
show up the differences between the two models. So lets be sure we use
the right model for the right task. Using the wrong model will lead to
either over complication (DoA when subcontracting is sufficient) or
security vulnerability (subcontracting when DoA is needed)

regards

David

On 08/06/2015 15:10, Adam Young wrote:
> On 06/06/2015 06:00 AM, David Chadwick wrote:
>> In order to do this fully, you will need to work out what all the
>> possible supply chains are in OpenStack, so that when any customer
>> starts any chain of events, there is sufficient information in the
>> message passed to the supplier that allows that supplier to order from
>> its supplier. This has to be ensured all the way down the chain, so that
>> important information that one supplier needs was not omitted by a
>> previous supplier higher up the chain. I suspect that the name of the
>> initial requestor (at least) will need to be passed all the way down the
>> chain.
> Yes, I think so.  This is in keeping with how I understand we need to
> unify delegation across Keystone constructs.
> 
> 1.  Tokens live too long.  They should be short and ephemeral, and if a
> user needs a new one to complete an action, getting one should be
> trivial.  They should be bound to the endpoint that is the target of the
> operation.  5 minutes makes sense as a length of life, as that is
> essentially "now"  when you factor in clock skew. Revocations on tokens
> to not make sense.
> 
> 2.  Delegation are long lived affairs.  If anything is going to take
> longer than the duration of the token, it should be in the context of a
> delegation, and the user should re-authenticate to prove identity. 
> Delegations need to be focused on workflow, not "all operations ther
> user can do"  which means that the Glance case discussed here is a good
> start of documenting "what do you need to get this job done?"
> 
> 
> We need to keep it light (not fill up a database) for normal operations,
> but maintain the chain of responsibility on a given operation.  Trusts
> are the closest thing we have to this model.
> 
> In the supply chain example, if one company exchanges a good with
> another company, they don't care about the end user, because there is no
> realy connection between the good and the user yet;   if there is a
> problem, the original manufacterur can produce  another car identical to
> the first and replace it without the user being any the wiser.
> 
> Contrast this with picking kids up from daycare:  as a parent, I have to
> sign a form saying that my mother-in-law will be picking up the kids on
> a specific day.  My Mother-in-law is not authorized to sign a form that
> will allow her friend to pick the kids up.  My kids are very, very
> specific to me, and should be carefully handed off from approved
> supervisor to approved supervisor.
> 
> Fetching an image from Glance may well be a causal or a protected
> operation, depending on the image.
> 
> Casual if it is a global image: anyone in the world can do it, so no big
> deal.
> 
> Protected if, for example, the image is pre-populated with an enrollment
> secret.  Only the owners should be able to get at it
> 
> 
> 
>>
>> regards
>>
>> David
>>
>> On 06/06/2015 03:25, Bhandaru, Malini K wrote:
>>> Continuing with David’s example and the need to control access to a
>>> Swift object that Adam points out,
>>>
>>>  
>>> How about using the Glance token from glance-API service to
>>> glance-registry but carry along extra data in the call, namely user-id,
>>> domain, and public/private information, so the object can be access
>>> controlled.
>>>
>>>  
>>> Alternately and encapsulating token
>>>
>>>  
>>> <Glance-token <user-token>> -- keeping it simple, only two levels.  This
>>> protects from on the cusp expired user-tokens.
>>>
>>> Could check user quota before attempting the storage.
>>>
>>>  
>>> Should user not have paid dues, Glance knows which objects to garbage
>>> collect!
>>>
>>>  
>>> Regards
>>>
>>> Malini
>>>
>>>  
>>> *From:*Adam Young [mailto:ayoung at redhat.com]
>>> *Sent:* Friday, June 05, 2015 4:11 PM
>>> *To:* openstack-dev at lists.openstack.org
>>> *Subject:* Re: [openstack-dev] [Glance][Keystone] Glance and trusts
>>>
>>>  
>>> On 06/05/2015 10:39 AM, Dolph Mathews wrote:
>>>
>>>      
>>>      On Thu, Jun 4, 2015 at 1:54 AM, David Chadwick
>>>      <d.w.chadwick at kent.ac.uk <mailto:d.w.chadwick at kent.ac.uk>> wrote:
>>>
>>>      I did suggest another solution to Adam whilst we were in
>>> Vancouver, and
>>>      this mirrors what happens in the real world today when I order
>>> something
>>>      from a supplier and a whole supply chain is involved in creating
>>> the end
>>>      product that I ordered. This is not too dissimilar to a user
>>> requesting
>>>      a new VM. Essentially each element in the supply chain trusts
>>> the two
>>>      adjacent elements. It has contracts with both its customers and its
>>>      suppliers to define the obligations of each party. When
>>> something is
>>>      ordered from it, it trusts the purchaser, and on the strength of
>>> this,
>>>      it will order from its suppliers. Each element may or may not
>>> know who
>>>      the original customer is, but if it needs to know, it trusts the
>>>      purchaser to tell it. Furthermore the customer does not need to
>>> delegate
>>>      any of his/her permissions to his/her supplier. If we used such
>>> a system
>>>      of trust between Openstack services, then we would not need
>>> delegation
>>>      of authority and "trusts" as they are implemented today. It could
>>>      significantly simplify the interactions between OpenStack services.
>>>
>>>      
>>>      +1! I feel like this is the model that we started with in
>>> OpenStack,
>>>      and have grown additional complexity over time without much
>>> benefit.
>>>
>>>
>>> We could roll Glance into Nova, too, and get the same benefit.  There is
>>> a reason we have separate services.  GLance shoud not Trust Nova for all
>>> operations, just some.
>>>
>>> David's example elides the fact that there  are checks built in to the
>>> supply chain system to prevent cheating.
>>>
>>>
>>>
>>>
>>>
>>>  
>>>
>>>      regards
>>>      David
>>>
>>>
>>>      On 03/06/2015 21:03, Adam Young wrote:
>>>      > On 06/02/2015 12:57 PM, Mikhail Fedosin wrote:
>>>      >> Hello! I think it's a good time to discuss implementation of
>>>      trusts in
>>>      >> Glance v2 and v3 api.
>>>      >>
>>>      >> Currently we have two different situations during image creation
>>>      where
>>>      >> our token may expire, which leads to unsuccessful operation.
>>>      >>
>>>      >> First is connection between glance-api and glance-registry.
>>> In this
>>>      >> case we have a solution
>>> (https://review.openstack.org/#/c/29967/) -
>>>      >> use_user_token parameter in glance-api.conf, but it is True by
>>>      default
>>>      >> . If it's changed to False then glance-api will use its own
>>>      >> credentials to authorize in glance-registry and it prevents many
>>>      >> possible issues with user token expiration. So, I'm
>>> interested if
>>>      >> there are some performance degradations if we change
>>>      use_user_token to
>>>      >> False and what are the reasons against making it the default
>>> value.
>>>      >>
>>>      >> Second one is linked with Swift. Current implementation uploads
>>>      chunks
>>>      >> one by one and requires authorization each time. It may lead to
>>>      >> problems: for example we have to upload 100 chunks, after
>>> 99th one,
>>>      >> token expired and glance can't upload the last one, catches an
>>>      >> exception and tries to remove stale chunks from storage. Of
>>> course it
>>>      >> will fail, because token is not valid anymore, and that's why
>>> there
>>>      >> will be 99 garbage objects in the storage.
>>>      >> With Single-tenant mode glance uses its own credentials to
>>> upload
>>>      >> files, so it's possible to create new connection on each
>>> chunk upload
>>>      >> or catch Unauthorized exception and recreate connections only
>>> in that
>>>      >> cases. But with Multi-tenant mode there is no way to do it,
>>> because
>>>      >> user credentials are required. So it seems that trusts is the
>>>      only one
>>>      >> solution here.
>>>      > The problem with using trusts is that it would need to be created
>>>      > per-user, and that is going to be expensive.  It would be
>>> possible, as
>>>      > Heat does something of this nature:
>>>      >
>>>      > 1. User calls glance,
>>>      > 2. Glance creates a trust with some limitation, either time or
>>>      number of
>>>      > uses
>>>      > 3.  Trusts are used for all operations with swift.
>>>      > 4. Glance should clean up the trust when it is complete.
>>>      >
>>>      > I don't love the solution, but I think it is the best we have.
>>>      Ideally
>>>      > the user would opt in to the trust, but in this case, it is
>>> kindof
>>>      > implicit by them calling the API.
>>>      >
>>>      >
>>>      > We should limit the trust creation to only have those roles (or a
>>>      > subset) on the token used to create the trust.
>>>      >
>>>      >
>>>      >
>>>      >
>>>      >> I would be happy to hear your opinions on that matter. If you
>>> know
>>>      >> other situations where trusts are useful or some other
>>> approaches
>>>      >> please share.
>>>      >>
>>>      >> Best regards,
>>>      >> Mike Fedosin
>>>      >>
>>>      >>
>>>      >>
>>>      >>
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