Authenticating Using SAML

The SAML (Security Assertion Markup Language) adapter provides Single Sign On (SSO) and Single Log Off (SLO) in your deployment. Each Liferay DXP instance serves as either the Service Provider (SP) or the Identity Provider (IdP). An identity provider is a trusted provider that provides single sign-on for users to access other websites. A service provider is a website that hosts applications and grants access only to identified users with proper credentials.

Below is background on how SAML works. To jump right to its configuration, see the articles on Setting Up SAML as an Identity Provider or Setting Up SAML as a Service Provider for instructions on using the SAML adapter. Use the instructions to make the conceptual magic from this article come to life!

What’s new in Liferay Connector to SAML 2.0

The 5.0.0 version of the application for Liferay DXP brings some long-awaited improvements:

  • Liferay DXP acting as a Service Provider (SP) can now connect to multiple Identity Providers (IdP).
  • Developers have an extension point for customizing which Identity Providers to users can use to sign in.
  • Support for other Signature Algorithms (like SHA-256)
  • Signature method algorithm URL’s can now be blacklisted from the metadata (for example, disabling SHA-1: http://www.w3.org/2000/09/xmldsig#rsa-sha1)

Important SAML Paths

For reference, here are a few important SAML paths.

This URL is the default location of the metadata XML file:

[host]:[port]/c/portal/saml/metadata

Note that when configuring SAML, no importing of SAML certificates is required. Liferay DXP reads certificates from the SAML metadata XML file. If you want a third-party application like Salesforce to read a Liferay SAML certificate, you can export the Liferay DXP certificate from the keystore. The default keystore file is

[Liferay Home]/data/keystore.jks 

You can change this path in System Settings → SSO → SAML Configuration → Key Store Path.

Single Sign On

Both the IdP and the SP can initiate the Single Sign On process, and the SSO flow is different depending on each one. Regardless of how it’s initiated, SSO is configured for HTTPS between the SP and IdP, so all transport-level communication is encrypted. SAML requests are signed using certificates configured in Liferay DXP, using the SAML Web Browser SSO profile as defined in the SAML 2.0 specification. In all cases, responses are sent using HTTP-POST or HTTP-Redirect. HTTP-POST is preferred because it reduces the risk that the URL is too long for a browser to handle.

Consider IdP initiated SSO first.

Identity Provider Initiated SSO

Sometimes a user enters the SSO cycle by sending a request directly from the browser to the IdP.

Figure 1: Identity Provider Initiated SSO

Figure 1: Identity Provider Initiated SSO

The SSO Request to the IdP

If Liferay DXP is the IdP, the IdP initiated SSO URL

  • Must specify the path as /c/portal/saml/sso.
  • Must include the entityId parameter which is the identifier to a previously configured Service Provider Connection (SPC).
  • May include a RelayState parameter which contains a URL encoded value where the user is redirected upon successful authentication. This URL should point to a location on the desired SPC (according to the SAML 2.0 standards section 3.4.3, this value must not exceed 80 bytes in length). It is useful to specify a landing page after SSO has been executed.

For non-Liferay DXP IdPs (Siteminder, ADFS, etc.), consult the vendor’s documentation on constructing IdP initiated SSO URLs.

If the IdP determines that the user isn’t authenticated, it prompts the user with the appropriate login screen.

The SSO Response from the IdP

Upon successful authentication, the IdP constructs a SAML Response. It includes attribute statements configured in the designated Service Provider Connection (SPC; see the next article on setting up the SPC in Liferay DXP’s SAML adapter).

The IdP sends the response to the Assertion Consumer Service URL. The request contains two parameters: SAMLResponse and RelayState.

The SP Processes the SSO Response

The SP validates and processes the SAML Response. Liferay DXP’s SAML solution requires signed SAMLResponse messages. This signature process ensures proper identification for the IdP and prevents potential SAML Response spoofing.

  • If one Liferay DXP instance is the IdP and another is the SP, make sure the SAML metadata XML file imported into the SP contains the IdP’s certificate.
  • If Liferay DXP is the IdP and another application is the SP, export the certificate from the IdP and import it into the SP’s certificate store.

If a RelayState is included in the SAML Response, the user is redirected to it. Otherwise the home page of the SP is served.

Service Provider Initiated SSO

Most of the time, authentication requests come from the Service Provider.

Figure 2: Service Provider Initiated SSO

Figure 2: Service Provider Initiated SSO

The SSO Request to the SP

When the user’s browser requests a protected resource or login URL on the SP, it triggers the SP initiated SSO process. When Liferay DXP is the SAML SP, SSO is initiated either by requesting /c/portal/login URL or a protected resource that requires authentication (for example, a document not viewable by the Guest Role). If the user requests a protected resource, its URL is recorded in the RelayState parameter. If the user requested /c/portal/login, the RelayState can be set by providing the redirect parameter. Otherwise, if the portal property auth.forward.by.last.path is set to true, the last accessed path is set as the RelayState. For non-Liferay DXP SPs, consult the vendor documentation on initiating SSO.

The AuthnRequest to the IdP

The SP looks up the IdP’s Single Sign On service URL and sends an AuthnRequest. When Liferay DXP is the SP it looks up the configured SAML Identity Provider Connection and sends a SAML AuthnRequest to the IdP’s Single Sign On service URL as defined in the SAML metadata XML document. Liferay DXP supports sending and receiving the AuthnRequest using HTTP-POST or HTTP-Redirect binding. HTTP-POST is preferred.

If the user doesn’t have an active session or if ForceAuthn was requested by the SP, the user must authenticate by providing credentials. When Liferay DXP is the IdP, authentication occurs in the Login Portlet. Liferay DXP decodes and verifies the AuthnRequest before requesting the user to authenticate.

The SSO Response from the IdP

After authentication, a SAML Response is constructed, sent to the Assertion Consumer Service URL of the SP, and verified. The IdP automatically makes this choice based on the SP metadata.

When Liferay DXP is configured as the IdP, any attributes configured on the Service Provider Connection are included in the response as attribute statements. The Assertion Consumer Service URL is looked up from the SAML metadata XML of the SP.

When Liferay DXP is configured as the SP, response and assertion signatures are verified. Liferay DXP requires the sender to be authenticated. This is done via whole message signature from the issuing IdP. Responses missing the signature are considered unauthenticated and the response is rejected. For non-Liferay DXP SP or IdP vendors, consult their documentation.

The user is redirected to the requested resource or to the URL contained in the RelayState parameter (for example, the last page the user accessed before initiating SSO).

Single Log Off

The Single Log Off request is sent from the user’s browser to the IdP or an SP, and the SLO flow differs in each case. First consider IdP initiated SLO.

Identity Provider Initiated SLO

Figure 3: Identity Provider Initiated SLO

Figure 3: Identity Provider Initiated SLO

The SLO Request to the IdP

An IdP initiated SLO request is sent directly to the IdP by the user’s browser. When Liferay DXP is the IdP, the IdP initiated SSO URL must specify the URL path as

/c/portal/logout

If the user is signed on to any configured SP, the SAML plugin takes over the logout process, displaying all the signed on services. The single logout screen displays the authentication status of each SP and whether any SPs can’t be logged out of (for example, if the SP is down or doesn’t support SLO). For non-Liferay DXP IdPs (Siteminder, ADFS, etc.) consult the vendor’s documentation on constructing IdP initiated SLO URLs.

The IdP sends a SAML LogoutRequest to the SP.

  • When Liferay DXP is configured as the IdP, the LogoutRequest is sent using either HTTP-POST, HTTP-Redirect, or SOAP binding. HTTP-Post binding is preferred but in its absence, the first available SLO endpoint with supported binding is selected.
  • When Liferay DXP is configured as the SP, supported bindings for LogoutRequest are HTTP-Post, HTTP-Redirect, or SOAP.
  • For other IdPs or SPs, please consult the vendor’s documentation.

The SLO Response from the SP

The SP delivers a LogoutResponse to the IdP.

The IdP sends a SAML LogoutRequest to the second SP.

The second SP then delivers the LogoutResponse to the IdP. The process is repeated for all SPs the user is logged into. When Liferay DXP is the IdP, Liferay DXP logs the user out after the last SP has delivered its LogoutResponse or has timed out.

Service Provider Initiated SLO

Figure 4: Service Provider Initiated SLO

Figure 4: Service Provider Initiated SLO

The SLO Request to the SP

In SP initiated SLO, the user’s browser sends a logout request directly to the SP. When Liferay DXP is configured as the SP, the SLO is initiated by requesting this logout URL:

/c/portal/logout

For other SPs, consult the vendor’s documentation on initiating SLO.

A SAML LogoutRequest is sent to the Single Log Out service URL of the IdP.

  • If Liferay DXP serves as the SP, the LogoutRequest is sent to the IdP configured by the IdP Connections tab of the SAML provider (see the next article to set up the IdP Connection) and the SLO service URL defined in the SAML metadata.

  • When Liferay DXP is the IdP, if the user has logged on to other SPs, the user is presented with a single logout screen with the status of each SP logout, flagging any that can’t be looged out of (some SPs might not support SLO or are currently down). If there are no other SPs to log out of, the SAML session terminates and the IdP destroys its session.

The SLO Response from the SP

If the user is logged in to additional SPs (beyond just the initiating SP), the IdP sends the SAML LogoutRequest to each one. When Liferay DXP is the IdP, the LogoutResponse is sent using either HTTP-Post, HTTP-Redirect, or SOAP binding.

Each SP delivers its LogoutResponse to the IdP. When Liferay DXP is the SP, the LogoutResponse is sent using either HTTP-Post, HTTP-Redirect or direct response to SOAP request.

After all additional SPs deliver their LogoutResponses to the IdP, the IdP destroys its SSO session. When Liferay DXP is the IdP, once the last SP has delivered its LogoutResponse or has timed out, the IdP destroys the Liferay DXP session, logging out the user.

Finally, the IdP sends a LogoutResponse to the SP that initiated SLO. The initiating SP terminates its SAML session and logs the user out.

« CAS (Central Authentication Service) Single Sign On AuthenticationSetting up Liferay DXP as a SAML Identity Provider »
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