Change Defaults

**cherry-pick to 3.0.x, 2.4.x**

(cherry picked from commit 09c612c)

# Conflicts:
#	spring-amqp/src/main/java/org/springframework/amqp/utils/SerializationUtils.java

build.gradle

@@ -293,6 +293,8 @@ subprojects { subproject ->
 		if (name ==~ /(testAll)/) {
 			systemProperty 'RUN_LONG_INTEGRATION_TESTS', 'true'
 		}
+		environment "SPRING_AMQP_DESERIALIZATION_TRUST_ALL", "true"
+
 		useJUnitPlatform()
 	}
 

spring-amqp/src/main/java/org/springframework/amqp/utils/SerializationUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006-2022 the original author or authors.
+ * Copyright 2006-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -37,6 +37,17 @@
  */
 public final class SerializationUtils {
 
+	private static final String TRUST_ALL_ENV = "SPRING_AMQP_DESERIALIZATION_TRUST_ALL";
+
+	private static final String TRUST_ALL_PROP = "spring.amqp.deserialization.trust.all";
+
+	private static final boolean TRUST_ALL;
+
+	static {
+		TRUST_ALL = Boolean.parseBoolean(System.getenv(TRUST_ALL_ENV))
+				|| Boolean.parseBoolean(System.getProperty(TRUST_ALL_PROP));
+	}
+
 	private SerializationUtils() {
 	}
 
@@ -136,11 +147,12 @@ protected Class<?> resolveClass(ObjectStreamClass classDesc)
 	 * @since 2.1
 	 */
 	public static void checkAllowedList(Class<?> clazz, Set<String> patterns) {
-		if (ObjectUtils.isEmpty(patterns)) {
+		if (TRUST_ALL && ObjectUtils.isEmpty(patterns)) {
 			return;
 		}
 		if (clazz.isArray() || clazz.isPrimitive() || clazz.equals(String.class)
-				|| Number.class.isAssignableFrom(clazz)) {
+				|| Number.class.isAssignableFrom(clazz)
+				|| String.class.equals(clazz)) {
 			return;
 		}
 		String className = clazz.getName();
@@ -149,7 +161,10 @@ public static void checkAllowedList(Class<?> clazz, Set<String> patterns) {
 				return;
 			}
 		}
-		throw new SecurityException("Attempt to deserialize unauthorized " + clazz);
+		throw new SecurityException("Attempt to deserialize unauthorized " + clazz
+				+ "; add allowed class name patterns to the message converter or, if you trust the message orginiator, "
+				+ "set environment variable '"
+				+ TRUST_ALL_ENV + "' or system property '" + TRUST_ALL_PROP + "' to true");
 	}
 
 }

spring-amqp/src/test/java/org/springframework/amqp/support/converter/AllowedListDeserializingMessageConverterTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2019 the original author or authors.
+ * Copyright 2016-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,7 +17,7 @@
 package org.springframework.amqp.support.converter;
 
 import static org.assertj.core.api.Assertions.assertThat;
-import static org.assertj.core.api.Assertions.fail;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 
 import java.io.Serializable;
 import java.util.Collections;
@@ -40,7 +40,11 @@ public void testAllowedList() throws Exception {
 		SerializerMessageConverter converter = new SerializerMessageConverter();
 		TestBean testBean = new TestBean("foo");
 		Message message = converter.toMessage(testBean, new MessageProperties());
-		Object fromMessage = converter.fromMessage(message);
+		// when env var not set
+//		assertThatExceptionOfType(SecurityException.class).isThrownBy(() -> converter.fromMessage(message));
+		Object fromMessage;
+		// when env var set.
+		fromMessage = converter.fromMessage(message);
 		assertThat(fromMessage).isEqualTo(testBean);
 
 		converter.setAllowedListPatterns(Collections.singletonList("*"));
@@ -54,15 +58,8 @@ public void testAllowedList() throws Exception {
 		fromMessage = converter.fromMessage(message);
 		assertThat(fromMessage).isEqualTo(testBean);
 
-		try {
-			converter.setAllowedListPatterns(Collections.singletonList("foo.*"));
-			fromMessage = converter.fromMessage(message);
-			assertThat(fromMessage).isEqualTo(testBean);
-			fail("Expected SecurityException");
-		}
-		catch (SecurityException e) {
-
-		}
+		converter.setAllowedListPatterns(Collections.singletonList("foo.*"));
+		assertThatExceptionOfType(SecurityException.class).isThrownBy(() -> converter.fromMessage(message));
 	}
 
 	@SuppressWarnings("serial")

src/reference/asciidoc/amqp.adoc

@@ -4321,14 +4321,15 @@ consider configuring which packages and classes are allowed to be deserialized.
 This applies to both the `SimpleMessageConverter` and `SerializerMessageConverter` when it is configured to use a
 `DefaultDeserializer` either implicitly or via configuration.
 
-By default, the allowed list is empty, meaning all classes are deserialized.
+By default, the allowed list is empty, meaning no classes will be deserialized.
 
 You can set a list of patterns, such as `thing1.*`, `thing1.thing2.Cat` or `*.MySafeClass`.
 
 The patterns are checked in order until a match is found.
 If there is no match, a `SecurityException` is thrown.
 
 You can set the patterns using the `allowedListPatterns` property on these converters.
+Alternatively, if you trust all message originators, you can set the environment variable `SPRING_AMQP_DESERIALIZATION_TRUST_ALL` or system property `spring.amqp.deserialization.trust.all` to `true`.
 ====
 
 [[message-properties-converters]]