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On Sep 21, 2014, at 9:59 PM, Adam Young <ayoung at redhat.com> wrote:

> On 09/19/2014 01:43 PM, Doug Hellmann wrote:
>> On Sep 19, 2014, at 6:56 AM, David Chadwick <d.w.chadwick at kent.ac.uk> wrote:
>> 
>>> 
>>> On 18/09/2014 22:14, Doug Hellmann wrote:
>>>> On Sep 18, 2014, at 4:34 PM, David Chadwick <d.w.chadwick at kent.ac.uk>
>>>> wrote:
>>>> 
>>>>> 
>>>>> On 18/09/2014 21:04, Doug Hellmann wrote:
>>>>>> On Sep 18, 2014, at 12:36 PM, David Chadwick
>>>>>> <d.w.chadwick at kent.ac.uk> wrote:
>>>>>> 
>>>>>>> Our recent work on federation suggests we need an improvement
>>>>>>> to the way the policy engine works. My understanding is that
>>>>>>> most functions are protected by the policy engine, but some are
>>>>>>> not. The latter functions are publicly accessible. But there is
>>>>>>> no way in the policy engine to specify public access to a
>>>>>>> function and there ought to be. This will allow an
>>>>>>> administrator to configure the policy for a function to range
>>>>>>> from very lax (publicly accessible) to very strict (admin
>>>>>>> only). A policy of "" means that any authenticated user can
>>>>>>> access the function. But there is no way in the policy to
>>>>>>> specify that an unauthenticated user (i.e. public) has access
>>>>>>> to a function.
>>>>>>> 
>>>>>>> We have already identified one function (get trusted IdPs
>>>>>>> "identity:list_identity_providers") that needs to be publicly
>>>>>>> accessible in order for users to choose which IdP to use for
>>>>>>> federated login. However some organisations may not wish to
>>>>>>> make this API call publicly accessible, whilst others may wish
>>>>>>> to restrict it to Horizon only etc. This indicates that that
>>>>>>> the policy needs to be set by the administrator, and not by
>>>>>>> changes to the code (i.e. to either call the policy engine or
>>>>>>> not, or to have two different API calls).
>>>>>> I don’t know what list_identity_providers does.
>>>>> it lists the IDPs that Keystone trusts to authenticate users
>>>>> 
>>>>>> Can you give a little more detail about why some providers would
>>>>>> want to make it not public
>>>>> I am not convinced that many cloud services will want to keep this
>>>>> list secret. Today if you do federated login, the public web page
>>>>> of the service provider typically lists the logos or names of its
>>>>> trusted IDPs (usually Facebook and Google). Also all academic
>>>>> federations publish their full lists of IdPs. But it has been
>>>>> suggested that some commercial cloud providers may not wish to
>>>>> publicise this list and instead require the end users to know which
>>>>> IDP they are going to use for federated login. In which case the
>>>>> list should not be public.
>>>>> 
>>>>> 
>>>>>> if we plan to make it public by default? If we think there’s a
>>>>>> security issue, shouldn’t we just protect it?
>>>>>> 
>>>>> Its more a commercial in confidence issue (I dont want the world to
>>>>> know who I have agreements with) rather than a security issue,
>>>>> since the IDPs are typically already well known and already protect
>>>>> themselves against attacks from hackers on the Internet.
>>>> OK. The weak “someone might want to” requirement aside, and again
>>>> showing my ignorance of implementation details, do we truly have to
>>>> add a new feature to disable the policy check? Is there no way to
>>>> have an “always allow” policy using the current syntax?
>>> You tell me. If there is, then problem solved. If not, then my request
>>> still stands
>> From looking at the code, it appears that something like True:”True” (or possibly True:True) would always pass, but I haven’t tested that.
> 
> Nope;  it errors out before it ever gets to the policy check, when it unpacks the token.

Which “token” do you mean, something in the policy parser or the keystone token? Are you saying that the syntax I suggested isn’t valid and so can’t be parsed, or that some other part of the code is throwing an error before the policy module is ever being invoked?

>> 
>> Doug
>> 
>>> regards
>>> 
>>> David
>>> 
>>>> Doug
>>>> 
>>>>> regards
>>>>> 
>>>>> David
>>>>> 
>>>>>>> If we can invent some policy syntax that indicates public
>>>>>>> access, e.g. reserved keyword of public, then Keystone can
>>>>>>> always call the policy file for every function and there would
>>>>>>> be no need to differentiate between protected APIs and
>>>>>>> non-protected APIs as all would be protected to a greater or
>>>>>>> lesser extent according to the administrator's policy.
>>>>>>> 
>>>>>>> Comments please
>>>>>> It seems reasonable to have a way to mark a function as fully
>>>>>> public, if we expect to really have those kinds of functions.
>>>>>> 
>>>>>> Doug
>>>>>> 
>>>>>>> regards
>>>>>>> 
>>>>>>> David
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
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>>>>>> 
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>>>>> 
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