OIDC logout endpoint support

Author: shawnhankim

README.md

@@ -36,7 +36,7 @@ If a [refresh token](https://openid.net/specs/openid-connect-core-1_0.html#Refre
 
 ### Logout
 
-Requests made to the `/logout` location invalidate both the ID token and refresh token by erasing them from the key-value store. Therefore, subsequent requests to protected resources will be treated as a first-time request and send the client to the IdP for authentication. Note that the IdP may issue cookies such that an authenticated session still exists at the IdP.
+Requests made to the `/logout` location invalidate both the ID token and refresh token by erasing them from the key-value store. Therefore, subsequent requests to protected resources will be treated as a first-time request and send the client to the IdP for authentication. By interacting with `$oidc_logout_endpoint` which is the end session endpoint of IdP, the authenticated session is ended at the IdP.
 
 ### Multiple IdPs
 
@@ -105,7 +105,7 @@ Manual configuration involves reviewing the following files so that they match y
 
   * **openid_connect_configuration.conf** - this contains the primary configuration for one or more IdPs in `map{}` blocks
     * Modify all of the `map…$oidc_` blocks to match your IdP configuration
-    * Modify the URI defined in `map…$oidc_logout_redirect` to specify an unprotected resource to be displayed after requesting the `/logout` location
+    * Modify the URI defined in `map…$oidc_logout_landing_page` to redirect browser after successful logout
     * Set a unique value for `$oidc_hmac_key` to ensure nonce values are unpredictable
     * If NGINX Plus is deployed behind another proxy or load balancer, modify the `map…$redirect_base` and `map…$proto` blocks to define how to obtain the original protocol and port number.
 

configure.sh

@@ -120,7 +120,7 @@ fi
 # Build an intermediate configuration file
 # File format is: <NGINX variable name><space><IdP value>
 #
-jq -r '. | "$oidc_authz_endpoint \(.authorization_endpoint)\n$oidc_token_endpoint \(.token_endpoint)\n$oidc_jwks_uri \(.jwks_uri)"' < /tmp/${COMMAND}_$$_json > /tmp/${COMMAND}_$$_conf
+jq -r '. | "$oidc_authz_endpoint \(.authorization_endpoint)\n$oidc_token_endpoint \(.token_endpoint)\n$oidc_jwks_uri \(.jwks_uri)\n$oidc_end_session_endpoint \(.end_session_endpoint)"' < /tmp/${COMMAND}_$$_json > /tmp/${COMMAND}_$$_conf
 
 # Create a random value for HMAC key, adding to the intermediate configuration file
 echo "\$oidc_hmac_key `openssl rand -base64 18`" >> /tmp/${COMMAND}_$$_conf
@@ -178,7 +178,7 @@ fi
 
 # Loop through each configuration variable
 echo "$COMMAND: NOTICE: Configuring $CONFDIR/openid_connect_configuration.conf"
-for OIDC_VAR in \$oidc_authz_endpoint \$oidc_token_endpoint \$oidc_jwt_keyfile \$oidc_hmac_key $CLIENT_ID_VAR $CLIENT_SECRET_VAR $PKCE_ENABLE_VAR; do
+for OIDC_VAR in \$oidc_authz_endpoint \$oidc_token_endpoint \$oidc_jwt_keyfile \$oidc_end_session_endpoint \$oidc_hmac_key $CLIENT_ID_VAR $CLIENT_SECRET_VAR $PKCE_ENABLE_VAR; do
 	# Pull the configuration value from the intermediate file
 	VALUE=`grep "^$OIDC_VAR " /tmp/${COMMAND}_$$_conf | cut -f2 -d' '`
 	echo -n "$COMMAND: NOTICE:  - $OIDC_VAR ..."

openid_connect.js

@@ -5,7 +5,7 @@
  */
 var newSession = false; // Used by oidcAuth() and validateIdToken()
 
-export default {auth, codeExchange, validateIdToken, logout};
+export default {auth, codeExchange, validateIdToken, logout, redirectPostLogout};
 
 function retryOriginalRequest(r) {
     delete r.headersOut["WWW-Authenticate"]; // Remove evidence of original failed auth_jwt
@@ -253,11 +253,26 @@ function validateIdToken(r) {
     }
 }
 
+// Default RP-Initiated or Custom Logout w/ OP as per:
+//  https://openid.net/specs/openid-connect-rpinitiated-1_0.html#RPLogout
+//  https://openid.net/specs/openid-connect-rpinitiated-1_0.html#RedirectionAfterLogout
+// An RP requests that the OP log out the end-user by redirecting the end-user's
+// User Agent to the OP's Logout endpoint.
 function logout(r) {
     r.log("OIDC logout for " + r.variables.cookie_auth_token);
-    r.variables.session_jwt = "-";
-    r.variables.refresh_token = "-";
-    r.return(302, r.variables.oidc_logout_redirect);
+    var queryParams = '';
+    if (r.variables.oidc_logout_extra_query_params) {
+        queryParams = '?' + r.variables.oidc_logout_extra_query_params;
+    }
+    r.variables.session_jwt   = '-';
+    r.variables.access_token  = '-';
+    r.variables.refresh_token = '-';
+    r.return(302, r.variables.oidc_end_session_endpoint + queryParams);
+}
+
+// Redirect URI after logged-out from the OP.
+function redirectPostLogout(r) {
+    r.return(302, r.variables.oidc_logout_landing_page);
 }
 
 function getAuthZArgs(r) {

openid_connect.server_conf

@@ -1,6 +1,8 @@
     # Advanced configuration START
     set $internal_error_message "NGINX / OpenID Connect login failure\n";
     set $pkce_id "";
+    set $oidc_logout_callback_uri "$redirect_base/_logout";
+    set $oidc_builtin_logout_query_params "post_logout_redirect_uri=$oidc_logout_callback_uri&id_token_hint=$session_jwt";
     resolver 8.8.8.8; # For DNS lookup of IdP endpoints;
     subrequest_output_buffer_size 32k; # To fit a complete tokenset response
     gunzip on; # Decompress IdP responses if necessary
@@ -67,14 +69,27 @@
     }
 
     location = /logout {
+        # RP-Initiated Logout to interact with $oidc_end_session_endpoint as per:
+        #  https://openid.net/specs/openid-connect-rpinitiated-1_0.html#RPLogout
         status_zone "OIDC logout";
-        add_header Set-Cookie "auth_token=; $oidc_cookie_flags"; # Send empty cookie
-        add_header Set-Cookie "auth_redir=; $oidc_cookie_flags"; # Erase original cookie
         js_content oidc.logout;
     }
 
     location = /_logout {
-        # This location is the default value of $oidc_logout_redirect (in case it wasn't configured)
+        # This location is a RP's callback URI which is called by the IdP after
+        # successful logout from the IdP by calling $oidc_logout_endpoint.
+
+        # Clean cookies
+        add_header Set-Cookie "auth_token=; $oidc_cookie_flags"; # Send empty cookie
+        add_header Set-Cookie "auth_redir=; $oidc_cookie_flags"; # Erase original cookie
+        add_header Set-Cookie "auth_nonce=; $oidc_cookie_flags"; 
+
+        js_content oidc.redirectPostLogout;
+    }
+
+    location = /logout_page {
+        # This location is a default value of $oidc_logout_landing_page as a 
+        # Built-in, simple logout page in case it wasn't configured.
         default_type text/plain;
         return 200 "Logged out\n";
     }

openid_connect_configuration.conf

@@ -28,6 +28,19 @@ map $host $oidc_jwt_keyfile {
     default "http://127.0.0.1:8080/auth/realms/master/protocol/openid-connect/certs";
 }
 
+map $host $oidc_end_session_endpoint {
+    default "http://127.0.0.1:8080/auth/realms/master/protocol/openid-connect/logout";
+}
+
+map $host $oidc_logout_extra_query_params {
+    # Each IdP may use different query params of the $oidc_end_session_endpoint.
+    # For example, Amazon Cognito requires `logout_uri`, and Auth0 requires
+    # `returnTo` instead of $oidc_default_logout_query_params.
+    # Define custom params without $oidc_builtin_logout_query_params if necessary.
+    default $oidc_builtin_logout_query_params;
+    #www.example.com "client_id=$oidc_client&logout_uri=$oidc_logout_callback_uri";
+}
+
 map $host $oidc_client {
     default "my-client-id";
 }
@@ -44,10 +57,10 @@ map $host $oidc_scopes {
     default "openid+profile+email+offline_access";
 }
 
-map $host $oidc_logout_redirect {
-    # Where to send browser after requesting /logout location. This can be
-    # replaced with a custom logout page, or complete URL.
-    default "/_logout"; # Built-in, simple logout page
+map $host $oidc_logout_landing_page {
+    # Where to redirect browser after successful logout from the IdP.
+    default "$redirect_base/logout_page"; # Built-in, simple logout page
+    #www.example.com $redirect_base;
 }
 
 map $host $oidc_hmac_key {