This customizer allows securing source code by controlling what code constructs are allowed. For example, if you only want to allow arithmetic operations in a groovy shell, you can configure this customizer to restrict package imports, method calls and so on.
Most of the security customization options found in this class work with either blacklist or whitelist. This means that, for a single option, you can set a whitelist OR a blacklist, but not both. You can mix whitelist/blacklist strategies for different options. For example, you can have import whitelist and tokens blacklist.
The recommended way of securing shells is to use whitelists because it is guaranteed that future features of the Groovy language won't be allowed by defaut. Using blacklists, you can limit the features of the languages by opting out, but new language features would require you to update your configuration.
If you set neither a whitelist nor a blacklist, then everything is authorized.
Combinations of import and star imports constraints are authorized as long as you use the same type of list for both. For example, you may use an import whitelist and a star import whitelist together, but you cannot use an import white list with a star import blacklist. static imports are handled separately, meaning that blacklisting an import does not prevent from using a static import.
Eventually, if the features provided here are not sufficient, you may implement custom AST filtering handlers, either implementing the StatementChecker interface or ExpressionChecker interface then register your handlers thanks to the addExpressionCheckers(org.codehaus.groovy.control.customizers.SecureASTCustomizer.ExpressionChecker...) and addStatementCheckers(org.codehaus.groovy.control.customizers.SecureASTCustomizer.StatementChecker...) methods.
Here is an example of usage. We will create a groovy classloader which only supports arithmetic operations and imports the java.lang.Math classes by default.
final ImportCustomizer imports = new ImportCustomizer().addStaticStars('java.lang.Math') // add static import of java.lang.Math
final SecureASTCustomizer secure = new SecureASTCustomizer()
secure.with {
closuresAllowed = false
methodDefinitionAllowed = false
importsWhitelist = []
staticImportsWhitelist = []
staticStarImportsWhitelist = ['java.lang.Math'] // only java.lang.Math is allowed
tokensWhitelist = [
PLUS,
MINUS,
MULTIPLY,
DIVIDE,
MOD,
POWER,
PLUS_PLUS,
MINUS_MINUS,
COMPARE_EQUAL,
COMPARE_NOT_EQUAL,
COMPARE_LESS_THAN,
COMPARE_LESS_THAN_EQUAL,
COMPARE_GREATER_THAN,
COMPARE_GREATER_THAN_EQUAL,
].asImmutable()
constantTypesClassesWhiteList = [
Integer,
Float,
Long,
Double,
BigDecimal,
Integer.TYPE,
Long.TYPE,
Float.TYPE,
Double.TYPE
].asImmutable()
receiversClassesWhiteList = [
Math,
Integer,
Float,
Double,
Long,
BigDecimal
].asImmutable()
}
CompilerConfiguration config = new CompilerConfiguration()
config.addCompilationCustomizers(imports, secure)
GroovyClassLoader loader = new GroovyClassLoader(this.class.classLoader, config)
| Modifiers | Name | Description |
|---|---|---|
interface |
SecureASTCustomizer.ExpressionChecker |
This interface allows the user to plugin custom expression checkers if expression blacklist or whitelist are not sufficient |
protected class |
SecureASTCustomizer.SecuringCodeVisitor |
This visitor directly implements the GroovyCodeVisitor interface instead of using the CodeVisitorSupport class to make sure that future features of the language gets managed by this visitor. |
interface |
SecureASTCustomizer.StatementChecker |
This interface allows the user to plugin custom statement checkers if statement blacklist or whitelist are not sufficient |
| Constructor and description |
|---|
SecureASTCustomizer
() |
| Methods inherited from class | Name |
|---|---|
class CompilationCustomizer |
getPhase |
An alternative way of setting constant types.
constantTypesBlackList - a list of classes.An alternative way of setting constant types.
constantTypesWhiteList - a list of classes.Set this option to true if you want your import rules to be checked against every class node. This means that if someone uses a fully qualified class name, then it will also be checked against the import rules, preventing, for example, instantiation of classes without imports thanks to FQCN.
indirectImportCheckEnabled - set to true to enable indirect checksSets the list of classes which deny method calls. Please note that since Groovy is a dynamic language, and this class performs a static type check, it will be reletively simple to bypass any blacklist unless the receivers blacklist contains, at a minimum, Object, Script, GroovyShell, and Eval. Additionally, it is necessary to also blacklist MethodPointerExpression in the expressions blacklist for the receivers blacklist to function as a security check.
receiversBlackList - the list of refused classes, as fully qualified namesAn alternative way of setting receiver classes.
receiversBlacklist - a list of classes.An alternative way of setting receiver classes.
receiversWhitelist - a list of classes.Sets the list of classes which may accept method calls.
receiversWhiteList - the list of accepted classes, as fully qualified namesSets the list of tokens which are blacklisted.
tokensBlacklist - the tokens. The values of the tokens must be those of TypesCopyright © 2003-2020 The Apache Software Foundation. All rights reserved.