Hi Steve
On 19/06/2013 20:56, Steve Martinelli wrote:
Hey David,
1. and 5. The delegate is not always known to keystone. The delegate (I
like to say consumer) would use an oauth client (web-based one here
_http://term.ie/oauth/example/client.php_); in an oauth flow, the
delegate requires a key/secret pair, they don't have to be already known
to keystone. (Apologies if my keystoneclient example led you to believe
that)
I know that in Oauth the consumer is not always known to the resource
provider (Keystone) but Oauth has security weaknesses in it which OAuth2
has fixed. So I would hope we are not going to use Oauth as the general
delegation model. I thought that the last design summit agreed that
Oauthv2 should be the right way to go for general delegation, and that
Oauth was only going to be used to replace Adam's existing delegation
scheme in which all the entities are known to Keystone.
So consider this, where the consumer is not known to Keystone.
Keystone trusts the user, and the user trusts the consumer to access his
resources on Keystone/OpenStack. Keystone has no idea who the consumer
is. Now we all know that users are easily tricked by spear phishing,
spam and the rest into trusting evil sites, so an evil consumer tricks
the user and now OpenStack is open to abuse as the naive user has given
his privileges away to an evil consumer. Surely you cannot be saying
that we should build support for this into OpenStack and Keystone are you?
So I would propose that the OAuth delegation system you are building is
restricted to only work with entities that are already known to Keystone
and have been registered there by trusted administrators, who should be
much more difficult to trick than naive users. In other words, Keystone
should not provide full unrestricted support for OAuth delegation, that
should be reserved for OAuthv2 (or whatever the group decides).
3. The authorizing step happens later on, 1e; any user with sufficient
credentials (the role matching the requested role), can authorize the
request token. If you don't expect the delegate to have knowledge of
roles, they shouldn't have knowledge of users either; so specifying one
wouldn't make things easier.
The delegate/consumer has knowledge of the user (delegator) since it is
in direct communication with him/her. (They have to be in order for the
secret to be passed between themselves). The delegate does not a priori
have any knowledge of what should be delegated to it (the role). Only
the delegator knows this. So I do not follow your logic.
2. Continuing with my previous answer, to authorize a request token, the
requested role would have to be a subset of the delegator roles.
Otherwise any user could authorize the token.
We are agreed on this point, for sure.
4. When using an oauth client, the delegate would input both the key and
secret; the client would then sign the request and send only the key and
*other oauth specific variables* over to the server side.
this worries me a bit. Consider the case of the evil consumer again, who
is not using any standard oauth client software, but is using his own.
We have to make sure that the protocol exchange strongly authenticates
the consumer, and I dont see how your exchange does this with only the
username/key and some unspecified magic oauth variables.
The last thing we want to do is knowingly introduce security
vulnerabilities into Keystone
regards
David
Thanks,
_____________________________________________
Steve Martinelli | A4-317 @ IBM Toronto Software Lab
Software Developer - OpenStack
Phone: (905) 413-2851
E-Mail: [email protected]
Inactive hide details for David Chadwick ---06/14/2013 10:45:34 AM---Hi
Steve Can I ask a few questions about this pleaseDavid Chadwick
---06/14/2013 10:45:34 AM---Hi Steve Can I ask a few questions about
this please
From: David Chadwick <[email protected]>
To: OpenStack Development Mailing List <[email protected]>,
Cc: Steve Martinelli/Toronto/IBM@IBMCA
Date: 06/14/2013 10:45 AM
Subject: Re: [openstack-dev] [Keystone] Reviewers wanted: Delegated Auth
a la Oauth
------------------------------------------------------------------------
Hi Steve
Can I ask a few questions about this please
1. Step 0b. Why do we need a new consumers table containing essentially
un/pw pairs for the delegate (called key/secret in the spec) when the
delegate is already known to keystone and can authenticate using its
existing credentials?
2. Step 1b. How does the delegate know which role to request? This is
unintuitive. A delegator (rather than delegate) knows the role he wants
to delegate. One would normally expect the delegator to request Keystone
to delegate this role to the named delegate, rather than the delegate
asking for a role to be delegated to it, since it requires an out of
band communications between the delegator and delegate to take place
before the delegation, in which the delegator tells the delegate its
un/pw and the role it should ask for. This seems to be a rather
contrived exchange of messages.
3. Step 1b. Why does the delegate not specify who should do the
delegation?. This is another unintuitive feature. A delegate would not
normally simply ask a service to give it a role, since the service is
not empowered to do this. It has to be the existing role holder (the
delegator) who has to authorise this, but in step 1b the delegator is
not mentioned.
4. In step 1b the delegate is only authenticating itself via its
username/key, and this was specified by the delegator when he created
the new consumer in step 0b. So the delegator could have used a simple
name/key like Fred, which means that it would then be very easy for
anyone to masquerade as the delegate. Wouldnt it be better to require
both the un/pw (key/secret) in this exchange rather than simply the key?
The same security weakness is in step 1f as well.
5. What is the purpose of having the delegate's secret?
regards
David
On 14/06/2013 14:31, Steve Martinelli wrote:
> Greetings!
>
> I've implemented the following blueprint for keystone: Delegated Auth a
> la Oauth [1
>
<https://blueprints.launchpad.net/keystone/+spec/delegated-auth-via-oauth>].
> The original spec [2 <https://gist.github.com/termie/5225817>] has a
> use case to help understand why we are providing this ability in
Keystone.
> If you're familiar with keystone, or just familiar with Oauth, I'd
> really appreciate your input. There are two change sets; a keystone
> patch [3 <https://review.openstack.org/#/c/29130/>] and keystoneclient
> patch [4 <https://review.openstack.org/#/c/30043/>].
>
> Thanks!
>
> References:
> 1.
https://blueprints.launchpad.net/keystone/+spec/delegated-auth-via-oauth
> 2. https://gist.github.com/termie/5225817
> 3. https://review.openstack.org/#/c/29130/
> 4. https://review.openstack.org/#/c/30043/
>
>
> Thanks,
>
> _____________________________________________
> Steve Martinelli | A4-317 @ IBM Toronto Software Lab
> Software Developer - OpenStack
> Phone: (905) 413-2851
> E-Mail: [email protected]
>
>
> _______________________________________________
> OpenStack-dev mailing list
> [email protected]
> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>
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