8366244: TLS1.3 ChangeCipherSpec message received after the client's Finished message should trigger a connection abort with "unexpected message"

Reviewed-by: hchao

src/java.base/share/classes/sun/security/ssl/ChangeCipherSpec.java

@@ -232,7 +232,8 @@ final class ChangeCipherSpec {
             tc.consumers.remove(ContentType.CHANGE_CIPHER_SPEC.id);
 
             // parse
-            if (message.remaining() != 1 || message.get() != 1) {
+            if (message.remaining() != 1 || message.get() != 1
+                    || tc.isNegotiated) {
                 throw tc.fatal(Alert.UNEXPECTED_MESSAGE,
                         "Malformed or unexpected ChangeCipherSpec message");
             }

test/jdk/sun/security/ssl/SSLEngineImpl/TLS13ChangeCipherSpecAfterFinished.java

@@ -0,0 +1,133 @@
+/*
+ * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+import static jdk.test.lib.Asserts.assertEquals;
+import static jdk.test.lib.Asserts.assertTrue;
+import static jdk.test.lib.Utils.runAndCheckException;
+
+import java.nio.ByteBuffer;
+import javax.net.ssl.SSLEngineResult.HandshakeStatus;
+import javax.net.ssl.SSLProtocolException;
+
+/*
+ * @test
+ * @bug 8366244
+ * @summary TLS1.3 ChangeCipherSpec message received after the client's
+ *          Finished message should trigger a connection abort with
+ *          "unexpected message"
+ * @library /javax/net/ssl/templates
+ *          /test/lib
+ * @run main/othervm TLS13ChangeCipherSpecAfterFinished false
+ * @run main/othervm TLS13ChangeCipherSpecAfterFinished true
+ */
+
+public class TLS13ChangeCipherSpecAfterFinished extends SSLEngineTemplate {
+
+    private static final ContextParameters testContextParams =
+            new ContextParameters("TLSv1.3", "PKIX", "SunX509");
+
+    private final String exMsg;
+
+    protected TLS13ChangeCipherSpecAfterFinished(String exMsg)
+            throws Exception {
+        super();
+        this.exMsg = exMsg;
+    }
+
+    @Override
+    protected ContextParameters getServerContextParameters() {
+        return testContextParams;
+    }
+
+    @Override
+    protected ContextParameters getClientContextParameters() {
+        return testContextParams;
+    }
+
+    public static void main(String[] args) throws Exception {
+        if (args.length != 1) {
+            throw new RuntimeException("Wrong number of arguments");
+        }
+
+        boolean useCompatibilityMode = Boolean.parseBoolean(args[0]);
+
+        if (useCompatibilityMode) {
+            // Test existing unexpected message detection mechanism
+            // with client's Middlebox Compatibility Mode on
+            // (which is the default).
+            new TLS13ChangeCipherSpecAfterFinished(
+                    "(unexpected_message) Unexpected content: 20").run();
+        } else {
+            // Switch off client Middlebox Compatibility Mode: do not send CCS
+            // immediately before the second flight. This is needed to reproduce
+            // the conditions for the issue to manifest itself.
+            System.setProperty("jdk.tls.client.useCompatibilityMode", "false");
+
+            // Test the fix.
+            new TLS13ChangeCipherSpecAfterFinished("(unexpected_message) "
+                    + "Malformed or unexpected ChangeCipherSpec "
+                    + "message").run();
+        }
+    }
+
+    protected void run() throws Exception {
+
+        // Complete handshake.
+        do {
+            clientEngine.wrap(clientOut, cTOs);
+            runDelegatedTasks(clientEngine);
+
+            serverEngine.wrap(serverOut, sTOc);
+            runDelegatedTasks(serverEngine);
+
+            cTOs.flip();
+            sTOc.flip();
+
+            clientEngine.unwrap(sTOc, clientIn);
+            runDelegatedTasks(clientEngine);
+
+            serverEngine.unwrap(cTOs, serverIn);
+            runDelegatedTasks(serverEngine);
+
+            cTOs.compact();
+            sTOc.compact();
+        } while (serverEngine.getHandshakeStatus()
+                != HandshakeStatus.NOT_HANDSHAKING);
+
+        // Send a valid CCS message after Finished.
+        ByteBuffer changeCipher = ByteBuffer.allocate(6);
+        // ContentType type: change_cipher_spec(20)
+        // ProtocolVersion:  0x0303
+        // uint16 length:    0x0001
+        // opaque fragment:  0x01
+        changeCipher.put(new byte[]{20, 3, 3, 0, 1, 1});
+        changeCipher.flip();
+
+        runAndCheckException(
+                () -> serverEngine.unwrap(changeCipher, serverIn),
+                ex -> {
+                    assertTrue(ex instanceof SSLProtocolException);
+                    assertEquals(exMsg, ex.getMessage());
+                });
+    }
+}