Remove TLSv1.1 from default protocols

This commit removes "TLSv1.1" from the list of default protocols in
Elasticsearch (starting with ES9.0)

TLSv1.1 has been deprecated by the IETF since March 2021

This affects a variety of TLS contexts, include
 - The HTTP Server (Rest API)
 - Transport protocol (including CCS and CCR)
 - Outgoing connections for features that have configurable SSL
   settings. This includes
    - reindex
    - watcher
    - security realms (SAML, OIDC, LDAP, etc)
    - monitoring exporters
    - inference services

In practice, however, TLSv1.1 has been disabled in most Elasticsearch
deployments since around 7.12 because most JDK releases have disabled
TLSv1.1 (by default) starting in April 2021

That is, if you run a default installation of Elasticsearch (for any
currently supported version of ES) that uses the bundled JVM then
TLSv1.1 is already disabled.
And, since ES9+ requires JDK21+, all supported JDKs ship with TLSv1.1
disabled by default.

In addition, incoming HTTP connections to Elastic Cloud deployments
have required TLSv1.2 or higher since April 2020

This change simply makes it clear that Elasticsearch does not
attempt to enable TLSv1.1 and administrators who wish to use that
protocol will need to explicitly enable it in both the JVM and in
Elasticsearch.

Resolves: #108057

Author: tvernum

libs/ssl-config/src/main/java/org/elasticsearch/common/ssl/SslConfigurationLoader.java

@@ -13,8 +13,6 @@
 
 import java.nio.file.Path;
 import java.security.KeyStore;
-import java.util.Arrays;
-import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
 import java.util.Set;
@@ -25,7 +23,6 @@
 import javax.net.ssl.TrustManagerFactory;
 
 import static org.elasticsearch.common.ssl.KeyStoreUtil.inferKeyStoreType;
-import static org.elasticsearch.common.ssl.SslConfiguration.ORDERED_PROTOCOL_ALGORITHM_MAP;
 import static org.elasticsearch.common.ssl.SslConfigurationKeys.CERTIFICATE;
 import static org.elasticsearch.common.ssl.SslConfigurationKeys.CERTIFICATE_AUTHORITIES;
 import static org.elasticsearch.common.ssl.SslConfigurationKeys.CIPHERS;
@@ -63,11 +60,7 @@
  */
 public abstract class SslConfigurationLoader {
 
-    static final List<String> DEFAULT_PROTOCOLS = Collections.unmodifiableList(
-        ORDERED_PROTOCOL_ALGORITHM_MAP.containsKey("TLSv1.3")
-            ? Arrays.asList("TLSv1.3", "TLSv1.2", "TLSv1.1")
-            : Arrays.asList("TLSv1.2", "TLSv1.1")
-    );
+    static final List<String> DEFAULT_PROTOCOLS = List.of("TLSv1.3", "TLSv1.2");
 
     private static final List<String> JDK12_CIPHERS = List.of(
         // TLSv1.3 cipher has PFS, AEAD, hardware support

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/XPackSettings.java

@@ -317,7 +317,7 @@ public static Setting<String> defaultStoredSecureTokenHashAlgorithmSetting(
         }, Property.NodeScope);
     }
 
-    public static final List<String> DEFAULT_SUPPORTED_PROTOCOLS = Arrays.asList("TLSv1.3", "TLSv1.2", "TLSv1.1");
+    public static final List<String> DEFAULT_SUPPORTED_PROTOCOLS = Arrays.asList("TLSv1.3", "TLSv1.2");
 
     public static final SslClientAuthenticationMode CLIENT_AUTH_DEFAULT = SslClientAuthenticationMode.REQUIRED;
     public static final SslClientAuthenticationMode HTTP_CLIENT_AUTH_DEFAULT = SslClientAuthenticationMode.NONE;