[Mondrian] Re: xmla security header processing

Luc Boudreau lucboudreau at gmail.com
Wed Apr 20 17:22:19 EDT 2011


I understand your requirement. You want to passthrough the credentials
through the servlet down to the OlapConnection. The architecture of the
Mondrian Server was not designed with that in mind, so my concern is that
such a feature is integrated 'the right way'. The proper way to do this
would be to modify the mondrian.server.Repository#getConnection method to
take a user and password as arguments. One downside is that we will depend
on Java Services Discovery to register the olap4j driver with the
DriverManager. One thing I don't like about that approach is the fact that
the server becomes 'aware' of the requests contents. I guess this was
unavoidable as soon as we attempted to factor out the Mondrian Server in
it's own project.

Write up some code and send it to this list. As you said, better discuss
over code than concepts :)


On Wed, Apr 20, 2011 at 4:15 PM, Michele Rossi <michele.rossi at gmail.com>wrote:

> hi,
> at the moment DefaultXmlaServlet simply ignores the XMLA SOAP security
> information.
> If there was ever anything like that in the code before it's certainly been
> removed now.
> In Excel (with Simba) you can type a username and a password in the dialog
> used to create a connection to an xmla server.
> Simba puts those two strings in a SOAP "Security" header that looks like my
> example below.
> I already have a working "mod" of DefaultXmlaServlet that I have been using
> for a while capable of reading and using that security header.
> Going back to your question about containers: it's certainly possible to
> protect access to "/xmla" using a standard http authentication mechanisms
> but Simba doesn't support any of that.
> Also even if Simba supported it the container would certainly not pass the
> authentication information to the XMLA servlet.
> And the biggest deal for me is using the credentials provided in Excel to
> open an authenticated Olap4j connection.
> I will put together a prototype in the next few days, I think it will be
> easier to discuss this with a piece of code to look at.
> thanks,
> Michele
> On 20 April 2011 21:19, Julian Hyde <jhyde at pentaho.com> wrote:
>>  I'd rather not spend hours researching this. But authentication problems
>> have been solved countless times before in the XMLA server code base.
>> Including authentication from Simba O2X. Can you look over the code and the
>> checkin history and find out how the previous solutions did it.
>> If there is someone on the developers list who has worked on these issues,
>> please speak up now.
>> Julian
>>  ------------------------------
>> *From:* Michele Rossi [mailto:michele.rossi at gmail.com]
>> *Sent:* Wednesday, April 20, 2011 10:52 AM
>> *To:* <jhyde at pentaho.com>
>> *Cc:* Mondrian developer mailinglist
>> *Subject:* Re: xmla security header processing
>>  hi,
>> as far as I know Axis is not a container but a library to create SOAP web
>> services.
>> There is nothing a container can do with that security information as it's
>> not transferred in a standard http way.
>> The username and password that you type in Excel when you create a new
>> SimbaO2x connection are sent to the server in the request header xml element
>> that I copied below.
>> So we either modify the xmla servlet or create an xmla callback with the
>> same features.
>> Do you agree on the general principle that the client (excel) credentials
>> should be used to open the olap4j connection?
>> And that the session id should be used to retrieve existing connections?
>> You certainly can't delegate any of these two features to the container.
>> thanks!
>> Michele
>> Sent from my iPhone
>> On 20 Apr 2011, at 18:19, "Julian Hyde" <jhyde at pentaho.com> wrote:
>>   I'm not an expert on the HTTP/SOAP stuff. But the general goal should
>> be to let the container (e.g. tomcat or apache axis) manage as much of this
>> stuff as possible. Maybe you can see how people have made authentication
>> work elsewhere in the XMLA servlet.
>> Julian
>>  ------------------------------
>> *From:* Michele Rossi [mailto:michele.rossi at gmail.com]
>> *Sent:* Wednesday, April 20, 2011 8:00 AM
>> *To:* Mondrian developer mailing list
>> *Cc:* <jhyde at pentaho.com>jhyde at pentaho.com
>> *Subject:* xmla security header processing
>> Hi,
>> I am writing some code to handle the xmla security header:
>>  <Header>
>>                        <Security xmlns="<http://schemas.xmlsoap.org/ws/2002/04/secext>
>> http://schemas.xmlsoap.org/ws/2002/04/secext">
>>                            <UsernameToken>
>>                                <Username>MICHELE</Username>
>>                                <Password
>> Type="PasswordText">ROSSI</Password>
>>                            </UsernameToken>
>>                        </Security>
>>                        <BeginSession mustUnderstand="1"
>> xmlns="urn:schemas-microsoft-com:xml-analysis" />
>>                     </Header>
>> Such header is sent out by XMLA clients such as SimbaO2X (Excel plugin).
>> My idea is to pass user credentials down to the connection manager and use
>> them to create new connections.
>> I also think that connections should be associated with sessions.
>> I am thinking of a Map that associates session IDs with OlapConnection
>> objects.
>> I can put all this logic directly in DefaultXmlaServlet or (probably) in a
>> "XmlaRequestCallback" class.
>> Which option do we want to go for?
>> I also have in mind another more specific bit of functionality: hiding
>> username / password in the session ID returned to the xmla client.
>> This can be useful especially in the case of a server going down and
>> forgetting a particular session id.
>> (Your user leaves Excel open for a couple of days and when he tries to use
>> the Pivot again he gets an error if the server has been bounced in the
>> meantime).
>> The other use case could be http load balancers.
>> As Excel does not send any cookies most load balancers would fail to apply
>> the "sticky session" policy and could redirect different xmla requests to
>> different cluster members.
>> Only one of those members would know about the specified session ID (in
>> other words only one of those servers would have an OlapConnection object
>> stored under the given session id) but the others could re-obtain the
>> credentials by de-crypting the session id.
>> I can make the encrypted session ID very secure - even to "clear text"
>> attacks.
>> I will discuss the details only if we think it's a feature worth having.
>> Michele
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