[security-dev] Undertow / IdentityManager and Digest Authentication

Darran Lofthouse darran.lofthouse at jboss.com
Thu May 2 03:33:21 EDT 2013

Just going to add a +1 here, I see the conversation progressed but 
overall I agree with what Stuart and Bill are saying.

Overall it feels that we are trying to stick to the decision of not 
allowing credentials to be query-able but immediately offering a 
solution that bypasses that.

The simple truth for digest based authentication and potentially other 
mechanisms is that we have no incoming credential to validate at all, 
all we have is a request - any attempt to validate this is using a 
credential validation API is already working around the API which I 
would think is a bad sign before integration within WildFly.

I do have ideas regarding Digest that we could follow to make this 
Credential available to the outside without actually passing around the 
raw bytes but I think overall as has been raised on this thread to guard 
against untrusted code is going to require a security manager.

Also I think providing a credential query API is going to end up being 
more secure than going for the approach of custom CredentialHandlers 
that let stored credentials out - at least with the API we know exactly 
where the credentials are being accessed, can define a set of security 
permissions on that API even add full auditing to the API.  Using the 
CredentialHandler approach we are really down to each newly added 
CredentialHandler doing that properly.

Darran Lofthouse.

On 02/05/13 02:57, Stuart Douglas wrote:
> The IDM is a user data store, and part of that user data is credentials.
> At some point you have to let authentication mechanisms get access to
> them (I know for some simple auth methods like a hashed password this is
> not the case as you can just query the backing store using the provided
> credential to see if they match, but we should not be designing for the
> simplest case).
> The CredentialHandler method still allows you to query the credentials,
> just in a more round about way. So far you have not given a single
> example where the retrieveCurrentCredential() method would allow access
> to a user credential, that the CredentialHandler technique would not.
> Can you give me any scenarios where this approach increases security, as
> this seems to be the premise that your argument is based on?
> IMHO the ability to retrieve a credential is a IDM operation, but once
> you also add credential validation it becomes an authentication manager
> as well (as I believe Darran has already said).
> Using the credential to pass state around is also very problematic, as
> there could be multiple different mechanisms that wish to use the same
> credential in different ways, which would mean that the credential would
> need to have mutable fields for all the different state these mechanisms
> need.
> I just think this approach will cause problems for the advanced cases,
> and does not provide any additional security. For digest this is the
> difference between the digest handler just grabbing the credential it
> needs and using it directly, vs registering a callback handler, and
> using the callback handler to expose information about the stored
> credential using mechanism specific fields in the credential.
> Also if another mechanism such as SASL is also using the same
> credentials it gets even more problematic. Do we need two different
> versions of the same credential stored per user, one for each
> implementation of CredentialHandler, or are we going to have some way of
> stacking credential handlers, and we just have to make sure the
> credential has implementation specific fields for each handler (and just
> hope that no third party wants to use the same credential classes with
> different state).
> I'm sure we could hack around all these problems, and I must admit I
> have not spent nearly as much time working on this as you guys, but it
> just seems like this approach will make it more difficult to extend the
> available authentication mechanisms than it needs to be.
> Stuart
> Anil Saldhana wrote:
>> Shane - you can add the API for this. But I would like to think about it further. I really do not like creds via IM interface.
>> On May 1, 2013, at 7:33 PM, Shane Bryzak<sbryzak at redhat.com>  wrote:
>>> Bill, I'm going to concede defeat on this one, so congrats on a
>>> well-fought victory ;)  The one saving grace with the IdentityManager is
>>> that in an EE environment it is actually wrapped by a
>>> SecuredIdentityManager, which allows for permission checks to be defined
>>> for every single IDM operation.  With this in mind, it should be trivial
>>> to implement a permission check for credential retrieval that restricts
>>> it to only allow the reading of credentials for the currently
>>> authenticated user (or whatever other permission logic the developer wants).
>>> So, with that in mind I propose the following additional methods for
>>> IdentityManager:
>>>       <T extends CredentialStorage>  T retrieveCurrentCredential(Agent
>>> agent, Class<T>  storageClass);
>>>       <T extends CredentialStorage>  List<T>  retrieveCredentials(Agent
>>> agent, Class<T>  storageClass);
>>> These will essentially delegate to the underlying CredentialStore, and
>>> if there is none (which will be the case in an LDAP-only configuration)
>>> you'll get an OperationNotSupportedException.
>>> Will this be sufficient for your requirements?
>>> Shane
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