OpenID Connect Authenticator for Tomcat

This is an authenticator implementation for Apache Tomcat 10 that allows web-applications to use OpenID Connect to log users in.

A complete sample web-application is available at https://github.com/boylesoftware/tomcat-oidcauth-sample.

A more complete README is avalaible at the original repo

Table of Contents

• Installation
• Configuration
• The Web-Application
  • The Login Page
  • The Login Error Page
  • Authorization Info

Installation

The binary release of the authenticator can be downloaded from this github

The JAR need to be added to the Tomcat's classpath, for example, by placing it in $CATALINA_BASE/lib directory (see Tomcat's Class Loader How-To for more info).

Configuration

The authenticator is added to Tomcat configuration as a Valve. Normally, it goes into the web-application's Context. For example, for Tomcat 10.0:

<Valve className="org.bsworks.catalina.authenticator.oidc.tomcat10.OpenIDConnectAuthenticator"
       providers="..." />

The authenticator is configured using the following attributes on the valve:

• providers (required) - JSON-like array of objects, each describing and configuring an OpenID Provider (OP) available to the application. The syntax differs from the standard JSON in that it does not use double quotes around the property names and values (to make it XML attribute value friendly). A property value must be surrounded with single quotes if it contains commas, curly braces or whitespace. Each object describing an OP includes the following properties:

  • issuer (required) - The OP's unique Issuer Identifier corresponding to the iss claim in the ID Token. The issuer identifier is a URL that is used for identifying the OP to the application, validating the ID Token iss claim and, unless documentConfigurationUrl property described below is included, to load the OP configuration document according to the OpenID Connect Discovery's Obtaining OpenID Provider Configuration Information process (by adding .well-known/openid-configuration to the issuer identifier to form the OP configuration document URL).

  • validIssPattern (optional) - A regex pattern to use to validate the "iss" claim in the ID Token. If unspecified, a valid "iss" ID Token claim must be exactly equal to the issuer value, which is the standard OpenID Connect specification behavior. The standard behavior can be overridden for non-standard IdP implementations using this configuration attribute. If specified, the regex is matched against the entire "iss" value (see java.util.regex.Matcher.matches() method).

  • name (optional) - Application specific OP name made available to the login page. If not specified, defaults to the issuer value.

  • clientId (required) - The client ID associated with the web-application at the OP.

  • clientSecret (optional) - The client secret. Note, that most of the OPs require a client secret to make calls to the OP endpoints. However, some OPs may support public clients so no client secret is utilized.

  • extraAuthEndpointParams (optional) - Extra parameters added to the query string of the OP's Authorization Endpoint URL. The value is an object with keys being the parameter names and value being the parameter values.

  • tokenEndpointAuthMethod (optional) - Explicitly specified authentication method for the OP's Token Endpoint. Normally the authenticator will use "client_secret_basic" if the OP configuration includes a client secret and "none" if it doesn't. This property, however, allows overriding that logic and forcing a specific authentication method. For the description of the authentication methods see Client Authentication. Note, that currently "client_secret_jwt" and "private_key_jwt" methods are not supported.

  • configUrl (optional) - URL for the OP configuration document. If not specified, the URL is automatically constructed from the issuer ID using the process defined in OpenID Connect Discovery. However, some non-standard OPs may have their configuration document at a different location. This property allows configuring such non-standard OPs. The deprecated (and still supported) name of this property is configurationDocumentUrl.

  • usernameClaim (optional) - Claim in the ID Token used as the username in the Realm. The default is sub, which is the ID of the user known to the OP. Often, however, claims such as email are more convenient to use as usernames. To use properties in nested objects in the ID Token, the usernameClaim supports the dot notaion.

  • additionalScopes (optional) - Space-separated list of scopes to add to the openid scope, always included, for the OP's Authorization Endpoint. For example, if email claim is used as the username, the email scope can be added (email claim is normally not included in the ID Token unless explicitly requested as part of the email, profile or similar scope at the Authorization Endpoint).

  • endpointHttpConnectTimeout (optional) - HTTP connection timeout in milliseconds for the OP endpoints. If unspecified, the httpConnectTimeout valve attribute is used.

  • endpointHttpReadTimeout (optional) - HTTP read timeout in milliseconds for the OP endpoints. If unspecified, the httpReadTimeout valve attribute is used.

  • configHttpConnectTimeout (optional) - HTTP timeout in milliseconds for connecting to the OP configuration document URL (see configUrl property). If unspecified, the httpConnectTimeout valve attribute is used.

  • configHttpReadTimeout (optional) - HTTP timeout in milliseconds for loading the OP configuration document (see configUrl property). If unspecified, the httpReadTimeout valve attribute is used.

  • jwksHttpConnectTimeout (optional) - HTTP timeout in milliseconds for connecting to the OP JWKS URL (see jwks_uri property in OpenID Provider Metadata). If unspecified, the httpConnectTimeout valve attribute is used.

  • jwksHttpReadTimeout (optional) - HTTP timeout in milliseconds for loading the OP JWKS (see jwks_uri property in OpenID Provider Metadata). If unspecified, the httpReadTimeout valve attribute is used.

  • optional (optional) - If "true", the OP is not required for the web-application operation. If there is any problem configuring the OP, such as inability to load the OP configuration document from configUrl, the OP can be excluded from the list of OPs available to the web-application as if it was never configured. If unspecified or "false", the OP is required and the web-application will fail to start unless it is able to fully configure the OP. This property may be useful to application that support multiple OPs, some of which are unreliable and go down from time to time. Once a failed OP is detected, either it's previous configuration is used or, if there is no previous configuration, it is excluded from the list of available OPs. The next attempt to configure it is taken after configRetryTimeout milliseconds.

  • configRetryTimeout (optional) - Milliseconds to wait until another attempt to configure a failed OP. Only relevant if optional is set to "true". Default is 10000 (10 seconds).

• usernameClaim (optional) - Default username claim to use for OPs that do not override it in their specific descriptors.

• additionalScopes (optional) - Default additional scopes to use for OPs that do not override it in their specific descriptors.

• hostBaseURI (optional) - Base URI for the web-application used to construct the redirect_uri parameter for the OP's Authorization Endpoint. The redirect_uri is constructed by appending <context_path>/j_security_check to the hostBaseURI value. Normally, there is no need to specify this configuration attribute as the authenticator can automatically construct it from the current request URI.

• noForm (optional) - If "true", the form-based authentication is disabled and only OpenID Connect authentication is allowed. The default is "false". The value of the flag is made available to the web-application's login page as well, so it can make a decision to display the login form or not.

• httpConnectTimeout (optional) - Timeout in milliseconds used for establishing server-to-server HTTP connections with the OP endpoints, configuration document and JWKS URLs (see java.net.URLConnection.setConnectTimeout()). This timeout applies to all configured OPs. Individual OP configurations can override this value and set more specific values for specific connectiob cases. Default is 5000 (5 seconds).

• httpReadTimeout (optional) - Timeout in milliseconds used for reading data in server-to-server HTTP connections with the OP, configuration document and JWKS URLs (see java.net.URLConnection.setReadTimeout()). This timeout applies to all configured OPs. Individual OP configurations can override this value and set more specific values for specific connectiob cases. Default is 5000 (5 seconds).

In addition to the attributes described above, all the attributes of the standard form-based authenticator are supported. For more information see Form Authenticator Valve.

Here is an example of the valve configuration with multiple OpenID Providers and use of the email address as the username:

<Valve className="org.bsworks.catalina.authenticator.oidc.tomcat10.OpenIDConnectAuthenticator"
       providers="[
           {
               name: Auth0,
               issuer: https://example.auth0.com/,
               clientId: 7x9e5ozKO0JZc6JdriadVEvLpodz0182,
               clientSecret: jBmfqhKmBYe-zvcQCju8MT3nfP4g6mUvex1BdpH8-Tz5mx7x8brpmQfgw_Nyu4Px
           },
           {
               name: Google,
               issuer: https://accounts.google.com,
               clientId: 234571258471-9l1hgspl0qtuqohn80gat3j0vqo61cho.apps.googleusercontent.com,
               clientSecret: FRQFgCcSzyurnNJG-xVvMs8L,
               extraAuthEndpointParams: {
                   hd: example.com
               }
           },
           {
               name: 'Amazon Cognito',
               issuer: https://cognito-idp.us-east-1.amazonaws.com/us-east-1_AGKCjG3dQ,
               clientId: lz63q5p6qfn1ibjup0hn7jwka,
               clientSecret: 1mz5n48ockpvqfirfkei7chgbo223ndgiblorrf4ksmcomr2itec
           },
           {
               name: 'Microsoft Azure AD',
               issuer: https://sts.windows.net/45185e72-2ac1-4371-acec-d0b6d4469ce2/,
               clientId: 817343e7-2f24-4951-acd1-8285665280c3,
               clientSecret: WLvE8nEz0zHOxrv1XrVLSzMd21URsx4i6owlv9059wk=
           },
           {
               name: 'Microsoft Azure AD 2',
               issuer: https://login.microsoftonline.com/45185e72-2ac1-4371-acec-d0b6d4469ce2/v2.0,
               clientId: 817343e7-2f24-4951-acd1-8285665280c3,
               clientSecret: PayteUNZ4142+^kv(FWv42%,
               tokenEndpointAuthMethod: client_secret_post
           },
           {
               name: Okta,
               issuer: https://example.okta.com,
               clientId: 0oa16n2pagwGjnf6w2z9,
               clientSecret: 7P_3LuCWhdl4QGoF38PxNDCoXRQB2QznVXf1s4CF
           },
           {
               name: empowerID,
               issuer: https://sso.empoweriam.com,
               configUrl: https://sso.empoweriam.com/oauth/.well-known/openid-configuration,
               clientId: 8c3e74b6-7dfb-451f-ac2f-219deb353a70,
               clientSecret: 17aebdf6-1177-4a5d-bff3-e33b7a8c0223,
               tokenEndpointAuthMethod: client_secret_post,
               usernameClaim: attrib.email
           }
       ]"
       usernameClaim="email" additionalScopes="email" />

The Web-Application

As mentioned earlier, the web-application is developed as if for form-based authentication. For example, the application's web.xml can include:

<login-config>
    <auth-method>FORM</auth-method>
    <realm-name>My Application</realm-name>
    <form-login-config>
        <form-login-page>/WEB-INF/jsps/login.jsp</form-login-page>
        <form-error-page>/WEB-INF/jsps/login-error.jsp</form-error-page>
    </form-login-config>
</login-config>

The Login Page

Normally, an application that uses form-based authentication has something like the following in the login.jsp:

<h1>Login</h1>

<form method="post" action="j_security_check">
  <ul>
    <li>
      <label for="usernameInput">Username</label>
      <div><input id="usernameInput" type="text" name="j_username"></div>
    </li>
    <li>
      <label for="passwordInput">Password</label>
      <div><input id="passwordInput" type="password" name="j_password"></div>
    </li>
    <li>
      <button type="submit">Submit</button>
    </li>
  </ul>
</form>

As an extension, the OpenID Connect Authenticator provides the login page with a request attribute under the name org.bsworks.oidc.authEndpoints with the list of authorization endpoints for each OP configured on the authenticator's valve. Each endpoint element includes two properties:

• issuer - The OP's Issuer Identifier.
• name - Application-specific OP name.
• url - The URL, to which to direct the user's browser for the login.

Also, org.bsworks.oidc.noForm request attribute contains the noForm flag from the authenticator's valve configuration. So, a login page that allows login using multiple OPs as well as the local login form may look like the following:

<h1>Login</h1>

<%-- offer OpenID Connect providers if authenticator is configured --%>
<c:set var="authEndpoints" value="${requestScope['org.bsworks.oidc.authEndpoints']}"/>
<c:if test="${!empty authEndpoints}">
<h2>Using OpenID Connect</h2>
<ul>
  <c:forEach items="${authEndpoints}" var="ep">
  <li><a href="${ep.url}"><c:out value="${ep.name}"/></a></li>
  </c:forEach>
</ul>
</c:if>

<%-- offer local login form if not explicitely disabled --%>
<c:if test="${!requestScope['org.bsworks.oidc.noForm']}">
<h2>Using Form</h2>
<form method="post" action="j_security_check">
  <ul>
    <li>
      <label for="usernameInput">Username</label>
      <div><input id="usernameInput" type="text" name="j_username"></div>
    </li>
    <li>
      <label for="passwordInput">Password</label>
      <div><input id="passwordInput" type="password" name="j_password"></div>
    </li>
    <li>
      <button type="submit">Submit</button>
    </li>
  </ul>
</form>
</c:if>

Some applications don't want to show any application-hosted login page at all. That may be the case if the authenticator is configured with a single OP and local form-based login is not allowed. So, the login.jsp then simply renders a redirect to the first OP authorization endpoint URL:

<c:redirect url="${requestScope['org.bsworks.oidc.authEndpoints'][0].url}"/>

Or something sophisticated, such as:

<%-- redirect to the OP if the only option --%>
<c:set var="authEndpoints" value="${requestScope['org.bsworks.oidc.authEndpoints']}"/>
<c:if test="${requestScope['org.bsworks.oidc.noForm'] and fn:length(authEndpoints) eq 1}">
  <c:redirect url="${authEndpoints[0].url}"/>
</c:if>

<%-- render the login page --%>
<html lang="en">
  ...
</html>

The Login Error Page

In addition to the standard form-based authenticator use cases, the login error page configured in the application deployment descriptor's form-login-config element is used by the OpenID Connect Authenticator when either the OP's Authorization or Token endpoint comes back with an error. In that case, the authenticator provides the error page with a request attribute under org.bsworks.oidc.error name. The value is a bean with the following properties:

• code - The error code. The standard codes are described in Authentication Error Response and Token Error Response of the OpenID Connect specification.
• description - Optional human-readable description of the error provided by the OP.
• infoPageURI - Optional URL of the page that contains more information about the error.

Also, both org.bsworks.oidc.authEndpoints and org.bsworks.oidc.noForm request attributes are made available the same way as for the login page. This allows having the login and the login error pages to be implemented in a single JSP.

Authorization Info

Every HTTP session successfully authenticated by the OpenID Connect Authenticator includes an authorization descriptor object in org.bsworks.oidc.authorization session attribute. The object exposes the following properties to the application:

• issuer - The OP's Issuer Identifier.
• issuedAt - A java.util.Date with the timestamp when the authorization was issued.
• accessToken - Optional Access Token, or null if none.
• tokenType - If Access Token is included, the token type (normally "Bearer"), or null if no Access Token is included.
• expiresIn - An integer number of seconds after the authorization (access token) issue when it expires. In some cases this value is unavailable, in which case it's -1. That means the expiration period is defined by the OP somewhere else.
• refreshToken - Optional refresh token, or null if none.
• scope - Optional token scope. Usually null, which means the requested scope.
• idToken - The ID Token.

More information can be found in section 5.1 of the OAuth 2.0 Authorization Framework specification.

Note, that exposing some of the information contained in the authorization object in the application pages may pose a security risk.