Tuesday, 16 May 2017

HTTP Server redirects for Weblogic 12c and SAML2

Last few months I got busy with SAML2 and Weblogic 12c as Service Provider. One with ADFS and another using SurfConext as an IdP.

In both cases a HTTP server is used as a reversed proxy, in one case it is Oracle HTTP Server 12c, in the other we use Apache. Although OHS is based on Apache, of course, it has the Weblogic proxy plugin enabled by default. With Apache this is not the case.

So there are a few things to consider.

WebLogic Proxy Plugin in Apache

The Managed server needs to ‘know’ that the End User approaches the application over TLS (HTTPS), although the HTTP Server ‘offloads’ the security. During the SAML authentication, Weblogic and the Identity Provider redirect the browser back-and-forth to authenthicate and eventually process the saml token. In the end the browser should be redirected to the application. If Weblogic does not ‘know’ the application is approached via an HTTP server over HTTPS, it might redirect to the HTTP channel.

To solve that, the HTTP server should use the Weblogic Proxy Plugin. To configure that, see Oracle® Fusion Middleware Using Oracle WebLogic Server Proxy Plug-Ins 12.1.2 - Configuring WLS Web Server Proxy Plug-In for Apache HTTP Server.

Set Proxy Plugin

To make use of the Weblogic proxy plugin, so that the AdminServer considers it, you need to tell it that it is 'fronted' by it.

To set it on managed server level, go to the server, tab Configuration->General:



Under Advanced, find the 'Weblogic Plug-In Enabled' option and set it to 'yes':
 You can do this on domain, cluster and managed server level. See also this A-team blog. In recent upgrades of Weblogic, the checkbox is replaced by a pulldown list.

Setting the Frondend Host

Another thing is that the URL that is used in the browser to connect to your application is the HTTP Server's host, not the Weblogic host. Also, propably the HTTP Server listens on port 80 (HTTP) and 443 (HTTPS), while your managed server might listen on a port in the 7000, 8000 or 9000 ranges.

But in the redirects, Weblogic has to redirect the application to the HTTP Server, so it needs to know what that address is. This registered in the FrontEnd Host. This is also a setting that  can be set on both Server and Cluster level. To set it on Server level, go to that server, tab Protocols->HTTP.

Then set the Frontend Host and the ports to the particular values of your HTTP Server.




Setting the Frontend HTTP Port to 0, means that the port is not fetched from the Header. So it will use the Managed Server port. However, the configuration of Apache (using the Weblogic Plugin) should be such that HTTP is not routed, but only HTTPS should be passed through. Otherwise set the HTTP Port also to 80.

Application Routing

The application has it's root URI. Let's say it is /MyServiceApp. Let's say OHS is running on the URL https://www.darwin-it.nl. Then the application is reachable on https://www.darwin-it.nl/MyServiceApp. This has to be routed to the sp_server managed server, running on port 7003. Then the routing in the HTTP Server using the following location definition:
<Location /MyServiceApp>
  NSSRequireSSL
  WLSRequest On
  WebLogicHost sp_server.darwin-it.local
  WebLogicPort 7003
</Location>

SAML2 URLs Routing

During the saml interchange the browser is at one point directed to https://www.darwin-it.nl/MyServiceAppsaml2/sp/acs/post. The part until 'MyServiceAppsaml2' is the url registered as 'Published Site URL' in the saml2 configuration, under "Servers" –> Managed Server –> "Federation Services" –> "SAML 2.0 General". The managed server expects to be called on the root URI '/saml2'. You could simply append the HTTP Servers listen-address with /saml2  and provide that as a Published Site URL. Like https://www.darwin-it.nl/saml2. This is ok if you have only one application. But what if you expect multiple Service Provider Applications, deployed on different Managed Servers? You might want to differentiate on the different services. So what if I wanted to use the URL:  https://www.darwin-it.nl/MyServiceAppsaml2? That is ok, if you rewrite the url in the HTTP Server. With the Weblogic Proxy Plugin you can do that with the PathTrim
and PathPrepend options:
<Location /MyServiceAppsaml2>
  NSSRequireSSL
  WLSRequest On
  WebLogicHost sp_server.darwin-it.local
  WebLogicPort 7003
  PathTrim /MyServiceAppsaml2
  PathPrepend /saml2
</Location>

From the request URI it removes the /MyServiceAppsaml2 part, as defined with the PathTrim option. With PathPrepend the URL is prepended/prefixed with /saml2.

Time Skew and TimeZones

With SAML2 timing is everything.  With only a bit of time difference between the Service Provider and Identity Provider, even less then a minute, you can get a succesful SAML token, but with the checking of it by the Service Provider, that is on your server, you can get:
<[Security:090377]Identity Assertion Failed, weblogic.security.spi.IdentityAssertionException: [Security:090377]Identity Assertion Failed, weblogic.security.spi.IdentityAssertionException: [Security:096537]Assertion is not yet valid (NotBefore condition).> 
####<Apr 26, 2017 1:27:26 PM CEST> <Debug> <SecuritySAML2Service> <Oracle5> <ManagedServer_1> <[ACTIVE] ExecuteThread: '5' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <884d7111-ffc4-46ad-b877-77395aa690a3-000031ce> <1493206046903> <BEA-000000> <exception info
javax.security.auth.login.LoginException: [Security:090377]Identity Assertion Failed, weblogic.security.spi.IdentityAssertionException: [Security:090377]Identity Assertion Failed, weblogic.security.spi.IdentityAssertionException: [Security:096537]Assertion is not yet valid (NotBefore condition).

To be able to compare the dates of the assertions requests and responses with the server time, it might be handy to have the service provider server run with the same time zone setting. You can do that in the setUserOverrides.cmd/.sh script in the $DOMAIN_HOME/bin folder.


Edit it and add the following lines (Windows format):
@rem set EXTRA_JAVA_PROPERTIES=%EXTRA_JAVA_PROPERTIES% -Duser.timezone='Europe/Amsterdam'
set EXTRA_JAVA_PROPERTIES=%EXTRA_JAVA_PROPERTIES% -Duser.timezone=GMT

Choose which line you want to have uncommented.

And make sure that server time is synced with internet or a central time server. Have it adapted regularly. And maybe force it to be updated.

Conclusion

The saml2 configuration on Weblogic is not so hard. But the difficulty is in the several layers and different parties involved. But I provided a few extra considerations and solutions here.

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