On Tue, Feb 26, 2019, at 16:33, Harsha wrote:
> Hi Colin,
>       
> "> I think Ismael and Gwen here bring up a good point.  The version of the 
> > request is a technical detail that isn't really related to 
> > authorization.  There are a lot of other technical details like this 
> > like the size of the request, the protocol it came in on, etc.  None of 
> > them are passed to the authorizer-- they all have configuration knobs 
> > to control how we handle them.  If we add this technical detail, 
> > logically we'll have to start adding all the others, and the authorizer 
> > API will get really bloated.  It's better to keep it focused on 
> > authorization, I think."
> 
> probably my previous email is not clear but I am agreeing with Gwen's point. 
> I am not in favor of extending authorizer to support this.
> 
> 
> "> Another thing to consider is that if we add a new broker configuration 
> > that lets us set a minimum client version which is allowed, that could 
> > be useful to other users as well.  On the other hand, most users are 
> > not likely to write a custom authorizer to try to take advantage of 
> > version information being passed to the authorizer.  So, I think using> a 
> > configuration is clearly the better way to go here.  Perhaps it can 
> > be a KIP-226 dynamic configuration to make this easier to deploy?"
> 
> Although minimum client version might help to a certain extent there 
> are other cases where we want users to not start using transactions for 
> example. My proposal in the previous thread was to introduce another 
> module/interface, let's say
> "SupportedAPIs" which will take in dynamic configuration to check which 
> APIs are allowed. 
> It can throw UnsupportedException just like we are throwing 
> Authorization Exception.

Hi Harsha,

We can already prevent people from using transactions using ACLs, right?  
That's what the IDEMPOTENT_WRITE ACL was added for.

In general, I think users should be able to think of ACLs in terms of "what can 
I do" rather than "how is it implemented."  For example, maybe some day we will 
replace FetchRequest with GetStuffRequest.  But users who have READ permission 
on a topic shouldn't have to change anything.  So I think the Authorizer 
interface should not be aware of individual RPC types or message versions.

best,
Colin


> 
> 
> Thanks,
> Harsha
> 
> 
> n Tue, Feb 26, 2019, at 10:04 AM, Colin McCabe wrote:
> > Hi Harsha,
> > 
> > I think Ismael and Gwen here bring up a good point.  The version of the 
> > request is a technical detail that isn't really related to 
> > authorization.  There are a lot of other technical details like this 
> > like the size of the request, the protocol it came in on, etc.  None of 
> > them are passed to the authorizer-- they all have configuration knobs 
> > to control how we handle them.  If we add this technical detail, 
> > logically we'll have to start adding all the others, and the authorizer 
> > API will get really bloated.  It's better to keep it focused on 
> > authorization, I think.
> > 
> > Another thing to consider is that if we add a new broker configuration 
> > that lets us set a minimum client version which is allowed, that could 
> > be useful to other users as well.  On the other hand, most users are 
> > not likely to write a custom authorizer to try to take advantage of 
> > version information being passed to the authorizer.  So, I think  using 
> > a configuration is clearly the better way to go here.  Perhaps it can 
> > be a KIP-226 dynamic configuration to make this easier to deploy?
> > 
> > cheers,
> > Colin
> > 
> > 
> > On Mon, Feb 25, 2019, at 15:43, Harsha wrote:
> > > Hi Ying,
> > >         I think the question is can we add a module in the core which 
> > > can take up the dynamic config and does a block certain APIs.  This 
> > > module will be called in each of the APIs like the authorizer does 
> > > today to check if the API is supported for the client. 
> > > Instead of throwing AuthorizationException like the authorizer does 
> > > today it can throw UnsupportedException.
> > > Benefits are,  we are keeping the authorizer interface as is and adding 
> > > the flexibility based on dynamic configs without the need for 
> > > categorizing broker APIs and it will be easy to extend to do additional 
> > > options,  like turning off certain features which might be in interest 
> > > to the service providers.
> > > One drawback,  It will introduce another call to check instead of 
> > > centralizing everything around Authorizer.
> > > 
> > > Thanks,
> > > Harsha
> > > 
> > > On Mon, Feb 25, 2019, at 2:43 PM, Ying Zheng wrote:
> > > > If you guys don't like the extension of authorizer interface, I will 
> > > > just
> > > > propose a single broker dynamic configuration: client.min.api.version, 
> > > > to
> > > > keep things simple.
> > > > 
> > > > What do you think?
> > > > 
> > > > On Mon, Feb 25, 2019 at 2:23 PM Ying Zheng <yi...@uber.com> wrote:
> > > > 
> > > > > @Viktor Somogyi-Vass, @Harsha, It seems the biggest concern is the
> > > > > backward-compatibility to the existing authorizers. We can put the new
> > > > > method into a new trait / interface:
> > > > > trait AuthorizerEx extends Authorizer {
> > > > >    def authorize(session: Session, operation: Operation, resource: 
> > > > > Resource,
> > > > > apiVersion: Short): Boolean
> > > > > }
> > > > >
> > > > > When loading an authorizer class, broker will check if the class
> > > > > implemented AuthorizerEx interface. If not, broker will wrapper the
> > > > > Authorizer object with an Adapter class, in which authorizer(...
> > > > > apiVersion) call is translated to the old authorizer() call. So that, 
> > > > > both
> > > > > old and new Authorizer is supported and can be treated as 
> > > > > AuthorizerEx in
> > > > > the new broker code.
> > > > >
> > > > > As for the broker dynamic configuration approach, I'm not sure how to
> > > > > correctly categorize the 40+ broker APIs into a few categories.
> > > > > For example, describe is used by producer, consumer, and admin. 
> > > > > Should it
> > > > > be controlled by producer.min.api.version or consumer.min.api.version?
> > > > > Should producer.min.api.version apply to transaction operations?
> > > > >
> > > > >
> > > > > On Mon, Feb 25, 2019 at 10:33 AM Harsha <ka...@harsha.io> wrote:
> > > > >
> > > > >> I think the motivation of the KIP is to configure which API we want 
> > > > >> to
> > > > >> allow for a broker.
> > > > >> This is challenging for a hosted service where you have customers 
> > > > >> with
> > > > >> different versions of clients.
> > > > >> It's not just about down conversion but for example transactions, 
> > > > >> there
> > > > >> is a case where we do not want to allow users to start using 
> > > > >> transactions
> > > > >> and there is no way to disable to this right now and as specified in 
> > > > >> the
> > > > >> KIP, having a lock on which client versions we support.
> > > > >> Authorizer's original purpose is to allow policies to be enforced for
> > > > >> each of the Kafka APIs, specifically in the context of security.
> > > > >> Extending this to a general purpose gatekeeper might not be suitable 
> > > > >> and
> > > > >> as mentioned in the thread every implementation of authorizer needs 
> > > > >> to
> > > > >> re-implement to provide the same set of functionality.
> > > > >> I think it's better to add an implementation which will use a 
> > > > >> broker's
> > > > >> dynamic config as mentioned in approach 1.
> > > > >>
> > > > >> Thanks,
> > > > >> Harsha
> > > > >>
> > > > >> On Sat, Feb 23, 2019, at 6:21 AM, Ismael Juma wrote:
> > > > >> > Thanks for the KIP. Have we considered the existing topic config 
> > > > >> > that
> > > > >> makes
> > > > >> > it possible to disallow down conversions? That's the biggest 
> > > > >> > downside in
> > > > >> > allowing older clients.
> > > > >> >
> > > > >> > Ismael
> > > > >> >
> > > > >> > On Fri, Feb 22, 2019, 2:11 PM Ying Zheng <yi...@uber.com.invalid>
> > > > >> wrote:
> > > > >> >
> > > > >> > >
> > > > >> > >
> > > > >> >
> > > > >>
> > > > >
> > > >
> > >
> >
>

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