ZOOKEEPER-5023: Allow to set TLS version and ciphers for AdminServer

zookeeper-docs/src/main/resources/markdown/zookeeperAdmin.md

@@ -2188,6 +2188,18 @@ Both subsystems need to have sufficient amount of threads to achieve peak read t
 
 #### AdminServer configuration
 
+**New in 3.10.0:** [AdminServer](#sc_adminserver) will use the following existing properties:
+
+* *ssl.quorum.ciphersuites* :
+  (Java system property: **zookeeper.ssl.quorum.ciphersuites**)
+  The enabled cipher suites to be used in TLS negotiation for AdminServer.
+  Default: Jetty default.
+
+* *ssl.quorum.enabledProtocols* :
+  (Java system property: **zookeeper.ssl.quorum.enabledProtocols**)
+  The enabled protocols to be used in TLS negotiation for AdminServer.
+  Default: Jetty default.
+
 **New in 3.9.0:** The following
 options are used to configure the [AdminServer](#sc_adminserver).
 
@@ -2674,6 +2686,27 @@ ssl.quorum.trustStore.password=password
 2019-08-03 15:44:55,403 [myid:] - INFO  [main:JettyAdminServer@170] - Started AdminServer on address 0.0.0.0, port 8080 and command URL /commands
 ```
 
+###### Restrict TLS protocols and cipher suites for SSL/TLS negotiation in AdminServer
+
+From 3.10.0 AdminServer uses the following already existing properties:
+
+* **ssl.quorum.enabledProtocols** to specify the enabled protocols,
+* **ssl.quorum.ciphersuites** to specify the enabled cipher suites.
+
+Add the following configuration settings to the `zoo.cfg` config file:
+
+```
+ssl.quorum.enabledProtocols=TLSv1.2,TLSv1.3
+ssl.quorum.ciphersuites=TLS_AES_128_GCM_SHA256,TLS_AES_256_GCM_SHA384,TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
+```
+
+To verify raise the log level of JettyAdminServer to DEBUG and check that the following entries can be seen in the logs:
+
+```
+2026-03-11 11:38:01,102 [myid:] - DEBUG  [main:o.a.z.s.a.JettyAdminServer@159] - Setting enabled protocols: 'TLSv1.2,TLSv1.3'
+2026-03-11 11:38:01,102 [myid:] - DEBUG  [main:o.a.z.s.a.JettyAdminServer@166] - Setting enabled cipherSuites: 'TLS_AES_128_GCM_SHA256,TLS_AES_256_GCM_SHA384,TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384'
+```
+
 Available commands include:
 
 * *connection_stat_reset/crst*:

zookeeper-server/src/main/java/org/apache/zookeeper/server/admin/JettyAdminServer.java

@@ -154,6 +154,20 @@ public JettyAdminServer(
                 sslContextFactory.setTrustStorePassword(certAuthPassword);
                 sslContextFactory.setNeedClientAuth(needClientAuth);
 
+                String enabledProtocols = System.getProperty(x509Util.getSslEnabledProtocolsProperty());
+                if (enabledProtocols != null) {
+                    LOG.debug("Setting enabled protocols: '{}'", enabledProtocols);
+                    String[] enabledProtocolsArray = enabledProtocols.split(",");
+                    sslContextFactory.setIncludeProtocols(enabledProtocolsArray);
+                }
+
+                String sslCipherSuites = System.getProperty(x509Util.getSslCipherSuitesProperty());
+                if (sslCipherSuites != null) {
+                    LOG.debug("Setting enabled cipherSuites: '{}'", sslCipherSuites);
+                    String[] cipherSuitesArray = sslCipherSuites.split(",");
+                    sslContextFactory.setIncludeCipherSuites(cipherSuitesArray);
+                }
+
                 if (forceHttps) {
                     connector = new ServerConnector(server,
                             new SslConnectionFactory(sslContextFactory, HttpVersion.fromVersion(httpVersion).asString()),

zookeeper-server/src/test/java/org/apache/zookeeper/server/admin/JettyAdminServerTest.java

@@ -24,20 +24,32 @@
 import static org.junit.jupiter.api.Assertions.fail;
 import java.io.BufferedReader;
 import java.io.File;
+import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.InputStreamReader;
 import java.net.HttpURLConnection;
 import java.net.SocketException;
 import java.net.URL;
 import java.nio.file.Path;
 import java.security.GeneralSecurityException;
+import java.security.KeyStore;
+import java.security.KeyStoreException;
+import java.security.NoSuchAlgorithmException;
 import java.security.Security;
+import java.security.UnrecoverableKeyException;
+import java.security.cert.CertificateException;
 import java.security.cert.X509Certificate;
 import javax.net.ssl.HostnameVerifier;
 import javax.net.ssl.HttpsURLConnection;
+import javax.net.ssl.KeyManager;
+import javax.net.ssl.KeyManagerFactory;
 import javax.net.ssl.SSLContext;
+import javax.net.ssl.SSLHandshakeException;
 import javax.net.ssl.SSLSession;
+import javax.net.ssl.SSLSocket;
+import javax.net.ssl.SSLSocketFactory;
 import javax.net.ssl.TrustManager;
+import javax.net.ssl.TrustManagerFactory;
 import javax.net.ssl.X509TrustManager;
 import org.apache.zookeeper.PortAssignment;
 import org.apache.zookeeper.ZKTestCase;
@@ -65,6 +77,9 @@ public class JettyAdminServerTest extends ZKTestCase {
     static final String URL_FORMAT = "http://localhost:%d/commands";
     static final String HTTPS_URL_FORMAT = "https://localhost:%d/commands";
     private final int jettyAdminPort = PortAssignment.unique();
+    private static final String KEYSTORE_TYPE_JKS = "JKS";
+    private String keyStorePath;
+    private String trustStorePath;
 
     @BeforeEach
     public void enableServer() {
@@ -85,6 +100,8 @@ public void setupEncryption(@TempDir File tempDir) {
                                              .setTrustStorePassword("")
                                              .setTrustStoreKeyType(X509KeyType.EC)
                                              .build();
+            keyStorePath = x509TestContext.getKeyStoreFile(KeyStoreFileType.JKS).getAbsolutePath();
+            trustStorePath = x509TestContext.getTrustStoreFile(KeyStoreFileType.JKS).getAbsolutePath();
             System.setProperty(
                 "zookeeper.ssl.quorum.keyStore.location",
                 x509TestContext.getKeyStoreFile(KeyStoreFileType.PEM).getAbsolutePath());
@@ -148,6 +165,8 @@ public void cleanUp() {
         System.clearProperty("zookeeper.ssl.quorum.trustStore.password");
         System.clearProperty("zookeeper.ssl.quorum.trustStore.passwordPath");
         System.clearProperty("zookeeper.ssl.quorum.trustStore.type");
+        System.clearProperty("zookeeper.ssl.quorum.ciphersuites");
+        System.clearProperty("zookeeper.ssl.quorum.enabledProtocols");
         System.clearProperty("zookeeper.admin.portUnification");
         System.clearProperty("zookeeper.admin.forceHttps");
     }
@@ -306,6 +325,116 @@ private void queryAdminServer(String urlStr, boolean encrypted) throws IOExcepti
         assertTrue(line.length() > 0);
     }
 
+    @Test
+    public void testHandshakeWithSupportedProtocol() throws Exception {
+        System.setProperty("zookeeper.admin.forceHttps", "true");
+        System.setProperty("zookeeper.ssl.quorum.enabledProtocols", "TLSv1.3");
+
+        JettyAdminServer server = new JettyAdminServer();
+        try {
+            server.start();
+
+            // Use a raw SSLSocket to verify the handshake
+            SSLContext sslContext = createSSLContext(keyStorePath, "".toCharArray(), trustStorePath, "TLSv1.3");
+            SSLSocketFactory factory = sslContext.getSocketFactory();
+
+            try (SSLSocket socket = (SSLSocket) factory.createSocket("localhost", jettyAdminPort)) {
+                socket.startHandshake();
+                String negotiatedProtocol = socket.getSession().getProtocol();
+
+                // Verify that we actually landed on the protocol we expected
+                assertEquals("TLSv1.3", negotiatedProtocol,
+                        "The negotiated protocol should be TLSv1.3.");
+            }
+        } finally {
+            server.shutdown();
+        }
+    }
+
+    @Test
+    public void testHandshakeWithUnsupportedProtocolFails() throws Exception {
+        System.setProperty("zookeeper.admin.forceHttps", "true");
+        System.setProperty("zookeeper.ssl.quorum.enabledProtocols", "TLSv1.3");
+
+        JettyAdminServer server = new JettyAdminServer();
+        try {
+            server.start();
+
+            SSLContext sslContext = createSSLContext(keyStorePath, "".toCharArray(), trustStorePath, "TLSv1.1");
+            SSLSocketFactory factory = sslContext.getSocketFactory();
+
+            try (SSLSocket socket = (SSLSocket) factory.createSocket("localhost", jettyAdminPort)) {
+                SSLHandshakeException exception = assertThrows(SSLHandshakeException.class, socket::startHandshake);
+                assertEquals(
+                        "No appropriate protocol (protocol is disabled or cipher suites are inappropriate)",
+                        exception.getMessage(),
+                        "The handshake should have failed due to a protocol mismatch.");
+            }
+        } finally {
+            server.shutdown();
+        }
+    }
+
+    @Test
+    public void testCipherMismatchFails() throws Exception {
+        System.setProperty("zookeeper.admin.forceHttps", "true");
+        System.setProperty("zookeeper.ssl.quorum.ciphersuites", "TLS_AES_128_GCM_SHA256,TLS_AES_256_GCM_SHA384");
+
+        JettyAdminServer server = new JettyAdminServer();
+        try {
+            server.start();
+
+            SSLContext sslContext = createSSLContext(keyStorePath, "".toCharArray(), trustStorePath, "TLSv1.2");
+            SSLSocketFactory factory = sslContext.getSocketFactory();
+
+            try (SSLSocket socket = (SSLSocket) factory.createSocket("localhost", jettyAdminPort)) {
+                // Force the client to use a cipher NOT enabled for the AdminServer
+                String[] unsupportedCiphers = new String[]{"TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA"};
+                socket.setEnabledCipherSuites(unsupportedCiphers);
+
+                assertThrows(SSLHandshakeException.class, socket::startHandshake,
+                        "The handshake should have failed due to a cipher mismatch.");
+            }
+        } finally {
+            server.shutdown();
+        }
+    }
+
+    private SSLContext createSSLContext(String keystorePath, char[] password, String trustStorePath, String protocol)
+            throws Exception {
+        KeyManager[] keyManagers = getKeyManagers(keystorePath, password);
+        TrustManager[] trustManagers = getTrustManagers(trustStorePath, password);
+
+        SSLContext sslContext = SSLContext.getInstance(protocol);
+        sslContext.init(keyManagers, trustManagers, null);
+
+        return sslContext;
+    }
+
+    private static KeyManager[] getKeyManagers(String keystorePath, char[] password) throws KeyStoreException,
+            IOException, NoSuchAlgorithmException, CertificateException, UnrecoverableKeyException {
+        KeyStore keyStore = KeyStore.getInstance(KEYSTORE_TYPE_JKS);
+        try (FileInputStream fis = new FileInputStream(keystorePath)) {
+            keyStore.load(fis, password);
+        }
+
+        KeyManagerFactory kmf = KeyManagerFactory.getInstance(KeyManagerFactory.getDefaultAlgorithm());
+        kmf.init(keyStore, password);
+        return kmf.getKeyManagers();
+    }
+
+    public TrustManager[] getTrustManagers(String trustStorePath, char[] password) throws Exception {
+        KeyStore trustStore = KeyStore.getInstance(KEYSTORE_TYPE_JKS);
+        try (FileInputStream fis = new FileInputStream(trustStorePath)) {
+            trustStore.load(fis, password);
+        }
+
+        TrustManagerFactory tmf = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
+        tmf.init(trustStore);
+
+        return tmf.getTrustManagers();
+    }
+
     /**
      * Using TRACE method to visit admin server
      */