Security: fix TokenMetaData equals and hashcode (#30347)

The TokenMetaData equals method compared byte arrays using `.equals` on
the arrays themselves, which is the equivalent of an `==` check. This
means that a seperate byte[] with the same contents would not be
considered equivalent to the existing one, even though it should be.

The method has been updated to use `Array#equals` and similarly the
hashcode method has been updated to call `Arrays#hashCode` instead of
calling hashcode on the array itself.

test/framework/src/main/java/org/elasticsearch/test/ESTestCase.java

@@ -519,6 +519,19 @@ public static byte randomByte() {
         return (byte) random().nextInt();
     }
 
+    /**
+     * Helper method to create a byte array of a given length populated with random byte values
+     *
+     * @see #randomByte()
+     */
+    public static byte[] randomByteArrayOfLength(int size) {
+        byte[] bytes = new byte[size];
+        for (int i = 0; i < size; i++) {
+            bytes[i] = randomByte();
+        }
+        return bytes;
+    }
+
     public static short randomShort() {
         return (short) random().nextInt();
     }

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/security/authc/TokenMetaData.java

@@ -14,6 +14,7 @@
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 
@@ -74,13 +75,13 @@ public boolean equals(Object o) {
         if (o == null || getClass() != o.getClass()) return false;
 
         TokenMetaData that = (TokenMetaData)o;
-        return keys.equals(that.keys) && currentKeyHash.equals(that.currentKeyHash);
+        return keys.equals(that.keys) && Arrays.equals(currentKeyHash, that.currentKeyHash);
     }
 
     @Override
     public int hashCode() {
         int result = keys.hashCode();
-        result = 31 * result + currentKeyHash.hashCode();
+        result = 31 * result + Arrays.hashCode(currentKeyHash);
         return result;
     }
 

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/security/authc/TokenMetaDataTests.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+package org.elasticsearch.xpack.core.security.authc;
+
+import org.elasticsearch.common.io.stream.BytesStreamOutput;
+import org.elasticsearch.common.settings.SecureString;
+import org.elasticsearch.test.ESTestCase;
+import org.elasticsearch.test.EqualsHashCodeTestUtils;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+public class TokenMetaDataTests extends ESTestCase {
+
+    public void testEqualsAndHashCode() {
+        final int numKeyAndTimestamps = scaledRandomIntBetween(1, 8);
+        final List<KeyAndTimestamp> keyAndTimestampList = generateKeyAndTimestampListOfSize(numKeyAndTimestamps);
+        final byte[] currentKeyHash = randomByteArrayOfLength(8);
+        final TokenMetaData original = new TokenMetaData(keyAndTimestampList, currentKeyHash);
+
+        EqualsHashCodeTestUtils.checkEqualsAndHashCode(original, tokenMetaData -> {
+            final List<KeyAndTimestamp> copiedList = new ArrayList<>(keyAndTimestampList);
+            final byte[] copyKeyHash = Arrays.copyOf(currentKeyHash, currentKeyHash.length);
+            return new TokenMetaData(copiedList, copyKeyHash);
+        }, tokenMetaData -> {
+            final List<KeyAndTimestamp> modifiedList = generateKeyAndTimestampListOfSize(numKeyAndTimestamps);
+            return new TokenMetaData(modifiedList, currentKeyHash);
+        });
+
+        EqualsHashCodeTestUtils.checkEqualsAndHashCode(original, tokenMetaData -> {
+            BytesStreamOutput out = new BytesStreamOutput();
+            tokenMetaData.writeTo(out);
+            return new TokenMetaData(out.bytes().streamInput());
+        }, tokenMetaData -> {
+            final byte[] modifiedKeyHash = randomByteArrayOfLength(8);
+            return new TokenMetaData(keyAndTimestampList, modifiedKeyHash);
+        });
+    }
+
+    private List<KeyAndTimestamp> generateKeyAndTimestampListOfSize(int size) {
+        final List<KeyAndTimestamp> keyAndTimestampList = new ArrayList<>(size);
+        for (int i = 0; i < size; i++) {
+            keyAndTimestampList.add(
+                new KeyAndTimestamp(new SecureString(randomAlphaOfLengthBetween(1, 12).toCharArray()), randomNonNegativeLong()));
+        }
+        return keyAndTimestampList;
+    }
+}

x-pack/plugin/security/src/main/java/org/elasticsearch/xpack/security/authc/BytesKey.java

@@ -14,7 +14,7 @@
  * Simple wrapper around bytes so that it can be used as a cache key. The hashCode is computed
  * once upon creation and cached.
  */
-public class BytesKey {
+public final class BytesKey {
 
     final byte[] bytes;
     private final int hashCode;