Configuring Reflection

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When you have set the object format to java, you can configure clusters to restrict object creation using reflection during SQL execution.

Disallowing Reflection of Untrusted Java Classes

To prevent Hazelcast from constructing objects of arbitrary classes through reflection, you can allow or deny reflection for Java classes based on class name, package name, or prefix using the java-reflection-filter parameter.

When objects are constructed through reflection, the following filtering rules apply:

  • When the whitelist option is empty:

    • If the object’s class name or package name is blacklisted, reflection fails.

    • Otherwise, reflection is allowed.

  • When the whitelist option is populated:

    • If the object’s class name or package name is blacklisted, reflection fails.

    • If the object’s class name or package name is whitelisted, reflection is allowed

    • Otherwise, reflection fails.

When reflection fails, a SecurityException is thrown.

By default, reflection restriction filter is empty and all class names or package names are allowed.

If the reflection restriction filter is not empty, class names or package names with the specified prefixes are automatically added to the whitelist by default:

  • java

  • com.hazelcast.

  • [ (for primitives and arrays)

If you do not want to allow these default prefixes, set the defaults-disabled attribute to true.

  • XML

  • YAML

  • Java

<hazelcast>
  ...
  <sql>
    <java-reflection-filter defaults-disabled="true">
      <whitelist>
        <class>example.Foo</class>
        <package>com.acme.app</package>
        <prefix>com.hazelcast.</prefix>
        <prefix>java.</prefix>
        <prefix>javax.</prefix>
        <prefix>[</prefix>
      </whitelist>
      <blacklist>
        <class>com.acme.app.BeanComparator</class>
      </blacklist>
    </java-reflection-filter>
  </sql>
  ...
</hazelcast>
hazelcast:
  sql:
    java-reflection-filter:
      defaults-disabled: true
      whitelist:
        class:
          - example.Foo
        package:
          - com.acme.app
        prefix:
          - com.hazelcast.
          - java.
          - javax.
          - \[
      blacklist:
        class:
          - com.acme.app.BeanComparator
Config config = new Config();
JavaSerializationFilterConfig reflectionConfig = new JavaSerializationFilterConfig();
reflectionConfig.setDefaultsDisabled(true);
reflectionConfig.getBlacklist().addClasses(SomeDeniedClass.class.getName());
reflectionConfig.getWhitelist().addClasses(SomeAllowedClass.class.getName());
config.getSqlConfig().setJavaReflectionFilterConfig(reflectionConfig);
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