Thursday, 8 February 2018

WildFly Elytron - Implementing a Custom HTTP Authentication Mechanism

When WildFly Elytron is used to secure a web application is is possible to implement custom HTTP authentication mechanisms that can be registered using the Elytron subsystem, it is then possible to override the configuration within the deployment to make use of this mechanism without requiring modifications to the deployment.

This blog post explores a custom authentication mechanism that can make use of custom HTTP headers to receive a clear text username and password and use these for authentication.  Generally passing clear text passwords is something that should be voided, they are only used here to avoid over complicating the example.

This blog will be making use of two projects within the elytron-examples respository that can be found at: -

https://github.com/wildfly-security-incubator/elytron-examples


  • simple-webapp - A very simple secured web application that can be deployed to test the mechanism.
  • simple-http-mechanism - A small project containing the minimal pieces to develop a custom mechanism.

Mechanism Implementation

The major piece of any custom HTTP mechanism is going to be the actual implementation of the mechanism, all custom mechanisms are required to implement the interface HttpServerAuthenticationMechanism.html.

In general for a mechanism the evaluateRequest method is called to handle the request passing in a HttpServerRequest object, the mechanism processes the requests and uses one of the following callback methods on the request to indicate the outcome: -
For each of these callback methods it is possible to pass in an instance of a HttpServerMechanismResponder which can be used to send challenge information to the calling client, which responders are called will depend very much on the outcome of the other mechanisms in use concurrently.


The custom mechanism implemented for this blog can be found at CustomHeaderHttpAuthenticationMechanism.java

Where this custom mechanism sends a challenge the challenge is always the same so we can use a static instance of the responder to avoid creating a new one each time we need to challenge: -

    private static final HttpServerMechanismsResponder RESPONDER = new      
            HttpServerMechanismsResponder() {       
        public void sendResponse(HttpServerResponse response) throws 
                HttpAuthenticationException {
            response.addResponseHeader(MESSAGE_HEADER, "Please resubit the request with a username specified using the X-USERNAME and a password specified using the X-PASSWORD header.");
            response.setStatusCode(401);
        }
    };


The evaluateRequest method then follows a path that will be common to many mechanisms.


final String username = request.getFirstRequestHeaderValue(USERNAME_HEADER);
final String password = request.getFirstRequestHeaderValue(PASSWORD_HEADER);

if (username == null || username.length() == 0 || password == null || 
      password.length() == 0) {    
    request.noAuthenticationInProgress(RESPONDER);
    return;
}


In this first block the mechanism tests if it has authentication headers appropriate for this mechanism, if not 'noAuthenticationInProgress' is called to notify the framework this mechanism is not doing anything yet and passes the responder in case a response is needed to challenge the client.


NameCallback nameCallback = new NameCallback("Remote Authentication Name", 
                                              username);
nameCallback.setName(username);
final PasswordGuessEvidence evidence = new 
                PasswordGuessEvidence(password.toCharArray());
EvidenceVerifyCallback evidenceVerifyCallback = new 
                EvidenceVerifyCallback(evidence);
try {
    callbackHandler.handle(new Callback[] { nameCallback, 
                                            evidenceVerifyCallback });
} catch (IOException | UnsupportedCallbackException e) {
    throw new HttpAuthenticationException(e);
}

if (evidenceVerifyCallback.isVerified() == false) {
    request.authenticationFailed("Username / Password Validation Failed", 
                                 RESPONDER);
}


In this second block the mechanism takes the headers received from the client and uses them to perform authentication by passing Callbacks to the provided CallbackHandler.

After a successful authentication it is possible to associate any credentials received from the client with the resulting identity, this step is optional but can be useful.


try {
    callbackHandler.handle(new Callback[] {new IdentityCredentialCallback(
        new PasswordCredential(ClearPassword.createRaw(
                ClearPassword.ALGORITHM_CLEAR, 
                password.toCharArray())), true)});
} catch (IOException | UnsupportedCallbackException e) {
    throw new HttpAuthenticationException(e);
}

At this point the identity has been authenticated and the credential associated but no check has been performed to ensure the identity is allowed to login so the next step is an authorization.

try {
    callbackHandler.handle(new Callback[] {authorizeCallback});

    if (authorizeCallback.isAuthorized()) {
        callbackHandler.handle(new Callback[] { 
            AuthenticationCompleteCallback.SUCCEEDED });
        request.authenticationComplete();
    } else {
        callbackHandler.handle(new Callback[] { 
            AuthenticationCompleteCallback.FAILED });
        request.authenticationFailed("Authorization check failed.", RESPONDER);
    }
    return;
} catch (IOException | UnsupportedCallbackException e) {
    throw new HttpAuthenticationException(e);
}

In this last block finally an AuthenticationCompleteCallback is needed to indicate the overall outcome of the authentication as decided by the mechanism, the reason the mechanism makes this decision is because a mechanism could take into account additional information in addition beyond the outcomes from the callbacks - an an example the HTTP Digest information will asses the validity of the nonce late in the authentication process.

Mechanism Factory Implementation

After the mechanism implementation the next class required is a factory to return instances of the mechanism, factories implement the HttpAuthenticationFactory interface, in this example the factory only returns a single mechanism however a single factory could support multiple mechanisms.

Within the test project this is implemented in CustomMechanismFactory.java

The most important step within the factory is to double check the name of the mechanism requested, it is important for the factory to return null if it can not create the required mechanism.  The mechanism factory can also take into account properties in the Map passed in to decide if it can create the requested mechanism.

Advertising Availability

There are two different approaches that can be used to advertise the availability of a mechanism factory, the first is to implement a java.security.Provider with the HttpAuthenticationFactory registered as an available service once for each mechanism it supports.

This example however is very simple so instead of implementing a provider we use a java.util.ServiceLoader to discover the factory instead, to achieve this we add the descriptor org.wildfly.security.http.HttpServerAuthenticationMechanismFactory under META-INF/services the only contents required in this file are the fully qualified class name of the factory.

Mechanism Installation

At this stage the mechanism project can be built and installed in the application server as a module ready to be used, the project is a simple maven project so can be built with: -

    mvn clean install

For the next stage the application server does not need to be running, the following command can be executed within the jboss-cli to add the module to the application server: -

module add --name=org.wildfly.security.examples.custom-http \
 --resources=/path/elytron-examples/simple-http-mechanism/target/simple-http-mechanism-1.0.0.Alpha1-SNAPSHOT.jar \
 --dependencies=org.wildfly.security.elytron,javax.api

The required dependencies are very simple, the installed module just requires a dependency on the public Elytron API and the javax API for access to some of the common callbacks and related exceptions.

Testing - BASIC authentication

When testing changes within the application server it is often better to start with small changes and verify those are working before moving onto the next set of changes, often users that make a large number of changes at once find it difficult to track down at which stage an error was introduced.

The next step within this blog is to deploy the simple-webapp also in the elytron-examples repository and verify it works with HTTP BASIC authentication, once verified we will switch the configuration to use the new authentication mechanism.

Before starting the application server a new test account can be added using the add-user utility.

./add-user.sh -a -u testuser -p password -g Users

Now the application server can be started and the CLI connected to the application server.

When the sample application is deployed it will by default use the 'other' security domain so a mapping needs to be added to map this to an Elytron HTTP authentication factory: -

./subsystem=undertow/application-security-domain=other:add(
http-authentication-factory=application-http-authentication)

The simple-webapp can now be deployed directly using maven.

mvn wildfly:deploy

This application could be tested using a web browser as it is using a standard mechanism the browser would understand, however once we switch to using a custom mechanism the browser will not understand so it is better to test the call using a client that will allow us to manipulate the headers ourselves.

curl -v http://localhost:8080/simple-webapp/secured -u testuser:password

If everything is working output similar to the following should be seen (Some headers have been removed to make the output easier to read)

< HTTP/1.1 200 OK
...<
<html>
 <head><title>Secured Servlet</title></head>
 <body>
   <h1>Secured Servlet</h1>
   <p>
Current Principal 'testuser'    </p>
 </body>
</html>

At this stage authentication is being successfully applied to the web application backed by WildFly Elytron using the Elytron implementation of the HTTP BASIC authentication mechanism, the next step is to switch to using the custom mechanism.

Testing - Custom Mechanism

The first resource to add in the CLI is to discover the factory implementation.

./subsystem=elytron/service-loader-http-server-mechanism-factory=
custom-factory:add(module=org.wildfly.security.examples.custom-http)

After this is added a CLI command can be executed to immediately check which mechanisms the factory can create.

./subsystem=elytron/service-loader-http-server-mechanism-factory=
custom-factory:read-resource(include-runtime=true)
{
   "outcome" => "success",
   "result" => {
       "available-mechanisms" => ["CUSTOM_MECHANISM"],
       "module" => "org.wildfly.security.examples.custom-http"
   }
}
The next resource to add is a http-authentication-factory to tie the mechanism factory to a security-domain that will be used for the actual authentication.

./subsystem=elytron/http-authentication-factory=custom-mechanism:
add(http-server-mechanism-factory=custom-factory,
security-domain=ApplicationDomain,
mechanism-configurations=[{mechanism-name=CUSTOM_MECHANISM}])

The application-security-domain resource we added previously can now be updated to use this new http-authentication-factory.

./subsystem=undertow/application-security-domain=other:
write-attribute(name=http-authentication-factory, value=custom-mechanism)
./subsystem=undertow/application-security-domain=other:
write-attribute(name=override-deployment-config, value=true)

The second of those commands is important, the application is defined to use the BASIC authentication mechanism only, by overriding the deployment config the mechanisms from the http-authentication-factory will be used instead.

The server can now be reloaded.

:reload

The same curl command can be executed again but this time it is expected it will fail with output similar to the following.

curl -v http://localhost:8080/simple-webapp/secured -u testuser:password
< HTTP/1.1 401 Unauthorized
...
< X-MESSAGE: Please resubit the request with a username specified using the X-USERNAME and a password specified using the X-PASSWORD header.
...

Here the authentication mechanism has rejected the call and subsequently added a header describing how to authentication.

The curl command can now be modified to: -

curl -v http://localhost:8080/simple-webapp/secured -H "X-USERNAME:testuser" -H "X-PASSWORD:password"
< HTTP/1.1 200 OK
...
<
<html>
 <head><title>Secured Servlet</title></head>
 <body>
   <h1>Secured Servlet</h1>
   <p>
Current Principal 'testuser'    </p>
 </body>
</html>

The resulting output now shows authentication was successful again and the authenticated principal is 'testuser'.







Tuesday, 26 September 2017

WildFly Elytron - Add Kerberos Authentication To Existing Web Application

When using WildFly Elytron to secure a web application it is possible to customise the authentication policy without modifying the web application, this is something that could be very useful as an application transitions though different environments such as development, testing, staging, and production - in each of these environments a custom authentication policy can be used without requiring a custom build of the web application.

This blog post is going to take a simple web application secured by HTTP BASIC authentication and convert it to use WildFly Elytron using SPNEGO authentication with fallback to BASIC without repackaging the application.

Example Application

This blog post have been written using the following example web application: -

https://github.com/wildfly-security-incubator/elytron-examples/tree/master/simple-webapp

This application contains a single welcome page with a link to a secured servlet that requires the caller have the role 'Users', the resulting deployment contains a web.xml that specifies authentication should use HTTP BASIC authentication.

The example application contains no JBoss or WidFly specific descriptors or annotations and instead depends on the default configuration within the Undertow subsystem using the 'other' security domain which pulls the user information from the application-users.properties and application-roles.properties.

Test User

Within my test Kerberos environment the main user I test with is 'testuser', before proceeding to configure the server I will ensure there is an entry for this user in the properties files with the following command: -

  ./add-user.sh -a -u testuser -p password -g Users

Configuring the Server

These instructions are written using a recent build of WildFly 11 however it should be possible to use them against either the CR1 release or once available the Final release.

Although they are not in use by default the default server configuration of WildFly 11 contains many Elytron components already configured to work with the legacy security properties, the steps here will make use of those as much as is possible and just define new components to achieve SPNEGO authentication as well.

The next set of commands are all executed within the JBoss CLI.

When working with Kerberos in a test environment I tend to find it easier to define the realm and KDC information as system properties: -


./system-property=sun.security.krb5.debug:add(value=true)
./system-property=java.security.krb5.realm:add(value=ELYTRON.ORG)
./system-property=java.security.krb5.kdc:add(value=kdc.elytron.org)


The next command is to define the server's Kerberos identity.

./subsystem=elytron/kerberos-security-factory=test-server:add( \
    path=/home/darranl/src/kerberos/test-server.keytab, \
    principal=HTTP/test-server.elytron.org@ELYTRON.ORG, \
    debug=true) 


The existing 'ApplicationDomain' and the realm it already references are going to be used.

SPNEGO authentication by default results in an identities name containing the Kerberos realm as a suffix so will now define a principal transformer to strip the realm.

 ./subsystem=elytron/regex-principal-transformer= \
    realm-stripper:add( \
    pattern="@ELYTRON.ORG", replacement="")

The final step within the Elytron subsystem is to define a HTTP authentication factory that supports both SPNEGO and BASIC authentication.

./subsystem=elytron/http-authentication-factory=spnego-http-authentication:add(security-domain=ApplicationDomain, \
    http-server-mechanism-factory=global, \
    mechanism-configurations=[ \
    {mechanism-name=SPNEGO, \
    credential-security-factory=test-server, \
    pre-realm-principal-transformer=realm-stripper}, \
    {mechanism-name=BASIC} \
    ])

The ordering of the mechanism names was important here as we want SPNEGO to be the preferred authentication mechanism with fallback to BASIC if the web browser can not respond. 

For this specific example we will be overriding the mechanisms defined within the web.xml so it is important to only list the mechanisms we want to actually use.

The final configuration step is within the Undertow susbystem to configure any deployments that use the 'other' security domain to instead use the HTTP authentication factory defined here and override any defined authentication mechanisms.

/subsystem=undertow/application-security-domain=other:add( \
    http-authentication-factory=spnego-http-authentication, \
    override-deployment-config=true)

Deploy Example Application

If the web application has already been deployed the server should be reloaded / restarted for the new security policy to apply to it, alternatively it can be deployed using the WildFly Maven plug-in.

mvn wildfly:deploy

Access Web Application

For my Kerberos test environment the server is test-server.elytron.org so I can access the web application through the following URL: -

http://test-server.elytron.org:8080/simple-webapp

At this point if I access the web application after obtaining a Kerberos ticket for 'testuser' and subsequently click on the 'Access Secured Servlet' link SPNEGO authentication will silently take place for me as I have already configured my web browser to enable SPNEGO authentication.

If I don't have a local Kerberos ticket or if my web browser does not have SPNEGO authentication enabled I will receive the BASIC authentication prompt and will be able to use the username and password I defined at the start of this blog post.

One point to keep in mind, SPNEGO authentication is cached by default against the HTTP session - if switching from having a ticket to not having a ticket restart either the browser or the server.











Friday, 8 September 2017

Using WildFly Elytron with Undertow Standalone

The WildFly Elytron project has been developed to provide the security requirements of the WildFly application server, however the development of WildFly Elytron has produced a security framework which does not depend on the application and can be used outside of the application server.

This means that it is possible to use WildFly Elytron in situations outside of the application server, this blog post demonstrates how WildFly Elytron can be used to secure an embedded Undertow server.

If you visit the main page for Undertow towards the bottom of the page is a code example showing how to start a simple HelloWorld server using Async IO.

http://undertow.io/

This blog post goes one step further and illustrates how WildFly Elytron can be added to the example to secure access to the HttpHandler using HTTP Basic authentication.

The components demonstrated in this example are the same components we use within the application server, the difference being that they are programatically configured and wired together rather than using the subsystem for configuration.

The code for the example can be found in the project called 'undertow-standalone' in the Git repository https://github.com/wildfly-security-incubator/elytron-examples.

Dependencies

The example project has the following key dependencies although these will pull in some additional dependencies.

io.undertow:undertow-core
This is the main dependency on Undertow, this example is only demonstrating with the core Undertow APIs so the servlet dependency is not required.

org.wildfly.security:wildfly-elytron
This is the dependency on the WildFly Elytron security framework.

org.wildfly.security.elytron-web:undertow-server
The Undertow project does not have a dependency on WildFly Elytron and the Elytron project does not have a dependency on Undertow, the Elytron Web project acts as an intermediate project to join the two together.

In future releases of Elytron Web we may also be able to look into integration with other servers following a similar pattern to how we have integrated with Undertow.

Example

The initial example is very similar to the example on undertow.io, the main difference being the call to a method 'wrap' to wrap the HttpHandler.

    public static void main(String[] args) throws Exception {
        final SecurityDomain securityDomain = createSecurityDomain();

        Undertow server = Undertow.builder()
                .addHttpListener(8080, "localhost")
                .setHandler(wrap(new HttpHandler() {

          public void handleRequest(HttpServerExchange exchange) 
               throws Exception {
                                            
exchange.getResponseHeaders().
  put(Headers.CONTENT_TYPE, "text/plain");                       
exchange.getResponseSender().
  send("Hello " + securityDomain.getCurrentSecurityIdentity().getPrincipal().getName());
                    }
                 }, securityDomain)).build();
        server.start();
    }

The first thing to happen during wrapping is an Elytron security domain is assembled, this domain contains a single user 'elytron' with a password of 'Coleoptera'.

    private static SecurityDomain createSecurityDomain() throws Exception {
        PasswordFactory passwordFactory = PasswordFactory.getInstance(ALGORITHM_CLEAR, elytronProvider);

        Map<String, SimpleRealmEntry> passwordMap = new HashMap<>();
        passwordMap.put("elytron", new SimpleRealmEntry(Collections.singletonList(new PasswordCredential(passwordFactory.generatePassword(new ClearPasswordSpec("Coleoptera".toCharArray()))))));

        SimpleMapBackedSecurityRealm simpleRealm = new SimpleMapBackedSecurityRealm(() -> new Provider[] { elytronProvider });
        simpleRealm.setPasswordMap(passwordMap);

        SecurityDomain.Builder builder = SecurityDomain.builder()
                .setDefaultRealmName("TestRealm");

        builder.addRealm("TestRealm", simpleRealm).build();
        builder.setPermissionMapper((principal, roles) -> PermissionVerifier.from(new LoginPermission()));

        return builder.build();
    }

In this example a simple in memory security realm backed by a Map is used, however any of the other Elytron security realms could be used or even a custom security realm implementation if desired.

After assembling the security domain the next step is creating a HttpAuthenticationFactory, the HttpAuthenticationFactory is the overall authentication policy that makes authentication mechanisms backed by the security domain available.

    private static HttpAuthenticationFactory createHttpAuthenticationFactory(final SecurityDomain securityDomain) {
        HttpServerAuthenticationMechanismFactory providerFactory = new SecurityProviderServerMechanismFactory(() -> new Provider[] {elytronProvider});
        HttpServerAuthenticationMechanismFactory httpServerMechanismFactory = new FilterServerMechanismFactory(providerFactory, true, "BASIC");

        return HttpAuthenticationFactory.builder()
                .setSecurityDomain(securityDomain)
                .setMechanismConfigurationSelector(MechanismConfigurationSelector.constantSelector(
                        MechanismConfiguration.builder()
                                .addMechanismRealm(MechanismRealmConfiguration.builder().setRealmName("Elytron Realm").build())
                                .build()))
                .setFactory(httpServerMechanismFactory)
                .build();
    }

At this stage we can see how the original HttpHandler is wrapped using the resulting HttpAuthenticationFactory and some additional Elytron and Undertow APIs to enable security.

    private static HttpHandler wrap(final HttpHandler toWrap, final SecurityDomain securityDomain) {
        HttpAuthenticationFactory httpAuthenticationFactory = createHttpAuthenticationFactory(securityDomain);

        HttpHandler rootHandler = new ElytronRunAsHandler(toWrap);

        rootHandler = new AuthenticationCallHandler(rootHandler);
        rootHandler = new AuthenticationConstraintHandler(rootHandler);

        return ElytronContextAssociationHandler.builder()
                .setNext(rootHandler)
                .setMechanismSupplier(() -> {
                    try {
                        return Collections.singletonList(httpAuthenticationFactory.createMechanism("BASIC"));
                    } catch (HttpAuthenticationException e) {
                        throw new RuntimeException(e);
                    }
        }).build();
    }

Build and Run

The example project is a standard Maven project so provided Maven is installed along with Java 8 the project can be built using 'mvn install'.

Once built the server can be started using the exec plug-in 'mvn exec:exec'.  This should result in the server starting and listening on port 8080 for incoming requests.

Note: As an example project there is not a lot of output from the project to the console, feel free to add more output if desired to see each stage as it occurs.

After starting the project you should be able to access the server using curl.

undertow-standalone]$ curl -v http://127.0.0.1:8080/
*   Trying 127.0.0.1...
* TCP_NODELAY set
* Connected to 127.0.0.1 (127.0.0.1) port 8080 (#0)
> GET / HTTP/1.1
> Host: 127.0.0.1:8080
> User-Agent: curl/7.53.1
> Accept: */*
< HTTP/1.1 401 Unauthorized
< Connection: keep-alive
< WWW-Authenticate: Basic realm="Elytron Realm"
< Content-Length: 0
< Date: Fri, 08 Sep 2017 15:16:30 GMT
* Connection #0 to host 127.0.0.1 left intact

At this stage curl was not supplied with any user details so we can see the HTTP Basic authentication challenge and the request ends.

If we now provide a username and enter the password when prompted we see a full HTTP exchange.

undertow-standalone]$ curl -v http://127.0.0.1:8080/ --user elytron
Enter host password for user 'elytron':
*   Trying 127.0.0.1...
* TCP_NODELAY set
* Connected to 127.0.0.1 (127.0.0.1) port 8080 (#0)
* Server auth using Basic with user 'elytron'
> GET / HTTP/1.1
> Host: 127.0.0.1:8080
> Authorization: Basic ZWx5dHJvbjpDb2xlb3B0ZXJh
> User-Agent: curl/7.53.1
> Accept: */*
< HTTP/1.1 200 OK
< Connection: keep-alive
< Content-Type: text/plain
< Content-Length: 13
< Date: Fri, 08 Sep 2017 15:17:45 GMT
* Connection #0 to host 127.0.0.1 left intact
Hello elytron

The 'Hello elytron' returned at the end is the message from the HttpHandler where 'elytron' is the name of the authenticated principal calling the HttpHandler.




Friday, 14 July 2017

WildFly Elytron - Principal Transformers, Realm Mappings, and Principal Decoders

Within the WildFly Elytron configuration it is possible to specify multiple principal transformers, realm mappers, and a principal decoder - this blog post is to describe how they all fit together during the authentication process.

During the authentication process the principal transformers and principal decoders form a very similar function in that they are both used to map principals from one form to another, principal transformers can also be used to validate a principal as an example double check the formatting so authentication can be terminated early if an invalid principal is detected.

At the appropriate state in the process that is being described in this blog post the realm mappers will then operate on the mapped principal to identify which security realm should be used to load the identity.

Here are a couple of diagrams to illustrate how these concepts fit together, the remainder of this blog post will describe the steps in more detail.

The first diagram illustrates the general states the authentication process undergoes to map the Principal used for authentication.

Identity Assignment States 
The next diagram illustrates how the various transformers, decoders, and mappers can be configured for Elytron authentication.

Configuration Relationships

Resolve Mechanism Configuration

When the authentication processes commences for a single authentication mechanism the first step is to resolve the MechanismConfiguration that should be used, this is resolved by taking into account the name of the selected mechanism, the host name, and the protocol.

During this stage the mechanism realm configuration will also be resolved, the authentication mechanism will either request this by name or if the mechanism does not request this then the first one in the list is used.

Note: The mechanism realm is specifically in relation to the realm name negotiated by the authentication mechanism if applicable and is independent of the security realm representing the identity store.

Pre Realm Mapping

The purpose of this state is to take the Principal from the form that was provided by the authentication mechanism and map it to the form that can be used to identify which security realm to use to load the identity.

At the very end of the authentication process the identity is represented by a SecurityIdentity which contains a single Principal, the Principal will be the one created by this mapping stage.

The principal transformers and principal decoder will be called in the following order: -

1. Mechanism Realm - pre-realm principal-transformer
2. Mechanism Configuration - pre-realm principal transformer
3. Security Domain - principal-decoder
4. Security Domain - pre-realm-principal-transformer

If the end result is a null principal and error will be reported and authentication will terminate.

Realm Mapping

The next stage is to take the mapping principal and map it to a realm name to identify the name of the Security Realm to use to load the identity.

Note:  At this stage the realm name is the name of the SecurityRealm as referenced by the SecurityDomain and is not the mechanism realm name.

The configuration will be inspected for the first realm mapper that can be found in the following locations: -

A. Mechanism Realm - realm-mapper
B. Mechanism Configuration - realm-mapper
C. Security Domain - realm-mapper

If a RealmMapper is identified but that mapper returns null when mapping the Principal then the default-realm specified on the Security Domain will be used instead.

If no RealmMapper is available then the default-realm on the SecurityDomain will be used.

Post Realm Mapping

After the realm has been identified a further round of principal transformation happens, this time the following transformers are called: -

5. Mechanism Realm - post-realm principal-transformer
6. Mechanism Configuration - post-realm principal-transformer
7. Security Domain - post-realm principal-transformer

As before if the result is a null principal an error will be reported and authentication will be terminated.

Final Principal Transformation

After the post realm mapping stage one final round of principal transforming takes place, this time the following transformers are called in order.

8. Mechanism Realm - final principal-transformer
9. Mechanism Configuration - final principal-transformer
10. Realm Mapping - principal-transformer

Once again a null principal will result in an error being reported and authentication being terminated.

Having to transformations after the realm has been identified allows for mechanism specific transformations to be applied both before and after domain specific transformations, if this is not required then either the post-realm principal transformers or the final principal-transformers can be used to obtain the same result.

The End

It is only now at the very end of principal transformation that the security realm previously identified will be call to obtain the RealmIdentity that is now used for authentication to continue.

The key points to keep in mind are: -

  • The Principal created by the pre-realm-principal-transformers is: -
    • The Principal used to map the SecurityRealm
    • The Principal that will be associated with the resulting SecurityIdentity.
  • The Principal created after the final principal transformers is: -
    • The Principal that will be passed to the SecurityRealm to obtain the RealmIdentity.


Wednesday, 24 February 2016

WildFly Elytron - SSL Configuration

One of the features being delivered by the upcoming WildFly Elytron integration within WildFly is the ability to provide SSL definitions centrally and then reference these definitions from elsewhere in the configuration.  This blog post demonstrates how to centrally configure SSL resources and subsequently use them to enable SSL both for web applications deployed to Undertow and for management of the server.  This blog post will also demonstrate how the same approach can be taken in domain mode to enable SSL to manage the server.

Environment

As WildFly 10 has been prepared for release the WildFly Elytron development has continued in parallel, to run the examples described here build the following three tags in order: -

https://github.com/wildfly-security-incubator/wildfly/tree/10.0.0.Final-Elytron1

The resulting server is the equivalent of a little before the WildFly 10 release but with the addition of the integration with WildFly Elytron.

After the WildFly build you will find a usable distribution in: -
 'wildfly/dist/target/wildfly-10.0.0.Final-Elytron1'.

Configuring SSL

For this example I am using a JKS KeyStore which contains a single entry which contains a private key and self signed certificate, certificate authority signed certificates would also be usable here.

To start up the application server with the WildFly Elytron subsystem included in the default configuration use the following command: -

bin/standalone.sh -c standalone-elytron.xml

Next start up the CLI and connect to the running server.

The approach taken with the WildFly Elytron subsystem is that different components required for security are defined independently of each other and then are assembled together for the final solution - this approach is taken to make it a lot easier to integrate custom implementations of the different components and to even allow other subsystems to advertise their own implementations within the application server so they can be used either with or in place of the Elytron implementations.

Within the CLI we next need to define three new resources within the Elytron subsystem: -
  1. KeyStore
  2. KeyManager(s)
  3. Server SSL Context
A new KeyStore can be added with the following command: -

./subsystem=elytron/keystore=server:add(type=jks, 
    path=/home/darranl/server.keystore, 
    password=keystore_password)

The arguments to this command should be fairly self explanatory.

The KeyManagers resource is then added with: -

./subsystem=elytron/key-managers=server:add(algorithm=SunX509, 
    keystore=server, 
    password=keystore_password)

In this command the 'keystore' argument is a reference to the KeyStore defined in the first command.

Then the Server SSL Context is defined: -

./subsystem=elytron/server-ssl-context=server:add(
    key-managers=server, 
    protocols=[TLSv1_2])

The 'key-managers' argument is a reference back to the KeyManagers resource defined in the previous command.

The server-ssl-context resource is where all policy information related to SSL will be defined, in this example however as this is a bare minimum definition we just reference the previously defined key-managers and specify that the protocol should be TLS 1.2.

Enable SSL With Undertow

Now that the resources are defined the next step is to enable the use of this resource within Undertow so the following command adds a https-listener referencing the previously defined server-ssl-context: -

./subsystem=undertow/server=default-server/
    https-listener=https:add(
        ssl-context=server, 
        socket-binding=https)

It should now be possible to connect a web browser to port 8443 and the previously defined SSL configuration within the Elytron subsystem will be used.

Enable SSL for Management over HTTP

Within the CLI with a couple more commands the same SSL resources can be used to enable SSL for access to the HTTP management interface: -

./core-service=management/management-interface=http-interface:
    write-attribute(
        name=ssl-context, 
        value=server)

The first command adds a reference to the previously defined server-ssl-context.

./core-service=management/management-interface=http-interface:
    write-attribute(
        name=secure-socket-binding, 
        value=management-https)

This second command then just enables HTTPS access on port 9993.

This last command will also require you to execute :reload for the changes to take effect.

Now you can connect to https://localhost:9993 and this will also be using the same previously defined SSL resources.

Enable SSL for Management over HTTP - Domain Mode

For this next step we now need to shut down the standalone server and start up domain mode with the host controller configured to enable Elytron.

bin/domain.sh --host-config=host-elytron.xml

When running within domain mode the host controller process can now contain it's own subsystems, first we need to repeat the three commands to add SSL resources but this time to the host controllers own Elytron subsystem.


./host=master//subsystem=elytron/keystore=server:
    add(
        type=jks, 
        path=/home/darranl/server.keystore, 
        password=keystore_password)

./host=master/subsystem=elytron/key-managers=server:
    add(
        algorithm=SunX509, 
        keystore=server, 
        password=keystore_password)

./host=master//subsystem=elytron/server-ssl-context=server:
    add(
        key-managers=server, 
        protocols=[TLSv1_2])

The only difference to the previous commands is in each of these the address has been prefixed with 'host=master' - this is so that the Elytron subsystem definition specific to the host controller is configured - apart from that it is exactly the same subsystem.

As before apart from a difference in address this SSL definition can be referenced in the same way: -

./host=master/core-service=management/
    management-interface=http-interface:
        write-attribute(
            name=ssl-context, 
            value=server)

How the port is specified in domain mode is slightly different so this is specified with: -

./host=master/core-service=management/
    management-interface=http-interface:
        write-attribute(
            name=secure-port, 
            value=9993)

The host controller can then be restarted with: -

./host=master:reload

At this point connections to https://localhost:9993 will be using this SSL definition.

Summary

The end result of this development will mean that administrators can learn how to define and tweak SSL policies all within the context of Elytron and the Elytron subsystem and then these policies can be applied across the application server where subsystems reference these resources - the aim being so that administrators do not need to learn how to configure SSL within each subsystem independently.

Advanced Configuration.

This blog post has focussed on the minimal steps required to get SSL enabled, I will follow up with some additional blog posts to cover the following features.

  • Alias Filtering
  • Cipher Suite Selection
  • Client Cert Authentication
  • Inspecting the KeyStore contents using the management model.
  • Inspecting (and invalidating) active sessions from the configured SSL resources.