Re: Apache 2.4, AAA, Shibboleth

On 06.03.2020 17:18, Russell Lundberg wrote:
> Andy, could your custom auth handler run before Shiboleth, test for a Shiboleth token? If not present, use push_handler to run Shiboleth? If the Shiboleth token or cookie is present, don’t run Shiboleth?

Well, the problem is that Shibboleth is quite "invasive" (no complaint here, it works that 
way it is supposed to and documented), in the sense that there are quite a few directives 
for it (as you can see below), and I am not quite sure if I can configure a section "with 
Shibboleth but not its handler", in order to only push the handler later.
For example, I have the feeling that just indicating "AuthType Shibboleth" (which is 
required) already puts the handler in the chain.
On the other hand, if I could just insert the "require shibbolet"
dynamically (instead of in the static config), that might do it.
But there seems to be no mod_perl API to add a "require" on-the-fly. "Requires" are just a 
list that the AUTHZ handler gets when called, and apparently each such handler only gets 
its own.
For example, the "Require UMA-user valid-user" below, results in our AUTHZ function 
"AUTH::UMA2->authz_user" being called, but in the list of requires we just get (our own) 
"valid-user".

But thanks for the suggestion. It /is/ the kind of thing I'm looking for.
Only maybe the opposite : how to "pop" the Shibboleth handler when it's there, and just 
for the current request.


> 
> Russell
> 
> Sent from my iPhone
> 
>> On Mar 6, 2020, at 08:26, André Warnier (tomcat/perl) <[email protected]> wrote:
>>
>> Hi experts.
>>
>> In our Apache 2.4(+mod_perl) setups, we use the following kind of thing :
>>
>> ...
>>     PerlAddAuthzProvider UMA-user AUTH::UMA2->authz_user
>> ...
>>     <Location "/esearchs/">
>>       AuthName ALUtop
>>       AuthType shibboleth
>>       PerlSetVar UMA_AuthType "SAML2"
>>       ShibRequestSetting requireSession 1
>>       ShibRequestMapperAuthz Off
>>       ShibUseHeaders On
>>       ShibUseEnvironment Off
>>       PerlSetVar UMA_Debug 3
>>       <RequireAll>
>>         Require UMA-user valid-user
>>         Require shibboleth
>>       </RequireAll>
>> ...
>> </Location>
>>
>> which basically means :
>> we combine 2 AAA methods :
>> - one is our own (AUTH::UMA2 above, mod_perl based)
>> - the other is SAML, via Shibboleth (and all the directives above with "shib" in them, correspond to the Shibboleth installation instructions)
>>
>> (The reason being : the corporate user authentication happens via SAML, but it does not provide us enough information about the user. So we run another additional scheme, which supplements the user information, in order to feed more complete data to our applications.)
>>
>> Our own AAA method is such, that once the user has been authenticated once, we set a token, such that for subsequent requests we do not need to re-authenticate the user.
>> But no matter what we do at that level, the Shibboleth authentication runs anyway.(*)
>>
>> And my question is : considering the above setup, would mod_perl provide a way, through some mod_perl API, to disable the Shibboleth authentication (on a request-by-request base), when our own authz module determines that we do not need it to run anymore for the current request ?
>>
>> (replace Shibboleth by any other authentication that would be configured in addition to our own; I'm looking for some "generic" mechanism, not only for Shibboleth).
>>
>> Or is it so that different authentication methods/modules don't insert themselves in any standard way which can easily be interfaced with in order to dynamically disable them ?
>>
>> Note: Shibboleth itself does caching of its prior authentication, and it is not really a big performance hit to re-run it each time, and we can live with it as it is. But in the absolute, it is unnecessary for 90% of the accesses to the applications, so it just sounds like disabling it would be a nice/efficient thing to do.
>>
>> I thought of dynamically removing the "Require shibboleth" e.g., but there does not seem to be an API to do that.
>>
>>