jaroslav@1646: /*
jaroslav@1646: * Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved.
jaroslav@1646: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
jaroslav@1646: *
jaroslav@1646: * This code is free software; you can redistribute it and/or modify it
jaroslav@1646: * under the terms of the GNU General Public License version 2 only, as
jaroslav@1646: * published by the Free Software Foundation. Oracle designates this
jaroslav@1646: * particular file as subject to the "Classpath" exception as provided
jaroslav@1646: * by Oracle in the LICENSE file that accompanied this code.
jaroslav@1646: *
jaroslav@1646: * This code is distributed in the hope that it will be useful, but WITHOUT
jaroslav@1646: * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
jaroslav@1646: * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
jaroslav@1646: * version 2 for more details (a copy is included in the LICENSE file that
jaroslav@1646: * accompanied this code).
jaroslav@1646: *
jaroslav@1646: * You should have received a copy of the GNU General Public License version
jaroslav@1646: * 2 along with this work; if not, write to the Free Software Foundation,
jaroslav@1646: * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
jaroslav@1646: *
jaroslav@1646: * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
jaroslav@1646: * or visit www.oracle.com if you need additional information or have any
jaroslav@1646: * questions.
jaroslav@1646: */
jaroslav@1646:
jaroslav@1646: package sun.invoke.util;
jaroslav@1646:
jaroslav@1646: import java.lang.reflect.Modifier;
jaroslav@1646: import static java.lang.reflect.Modifier.*;
jaroslav@1646: import sun.reflect.Reflection;
jaroslav@1646:
jaroslav@1646: /**
jaroslav@1646: * This class centralizes information about the JVM's linkage access control.
jaroslav@1646: * @author jrose
jaroslav@1646: */
jaroslav@1646: public class VerifyAccess {
jaroslav@1646:
jaroslav@1646: private VerifyAccess() { } // cannot instantiate
jaroslav@1646:
jaroslav@1646: private static final int PACKAGE_ONLY = 0;
jaroslav@1646: private static final int PACKAGE_ALLOWED = java.lang.invoke.MethodHandles.Lookup.PACKAGE;
jaroslav@1646: private static final int PROTECTED_OR_PACKAGE_ALLOWED = (PACKAGE_ALLOWED|PROTECTED);
jaroslav@1646: private static final int ALL_ACCESS_MODES = (PUBLIC|PRIVATE|PROTECTED|PACKAGE_ONLY);
jaroslav@1646: private static final boolean ALLOW_NESTMATE_ACCESS = false;
jaroslav@1646:
jaroslav@1646: /**
jaroslav@1646: * Evaluate the JVM linkage rules for access to the given method
jaroslav@1646: * on behalf of a caller class which proposes to perform the access.
jaroslav@1646: * Return true if the caller class has privileges to invoke a method
jaroslav@1646: * or access a field with the given properties.
jaroslav@1646: * This requires an accessibility check of the referencing class,
jaroslav@1646: * plus an accessibility check of the member within the class,
jaroslav@1646: * which depends on the member's modifier flags.
jaroslav@1646: *
jaroslav@1646: * The relevant properties include the defining class ({@code defc})
jaroslav@1646: * of the member, and its modifier flags ({@code mods}).
jaroslav@1646: * Also relevant is the class used to make the initial symbolic reference
jaroslav@1646: * to the member ({@code refc}). If this latter class is not distinguished,
jaroslav@1646: * the defining class should be passed for both arguments ({@code defc == refc}).
jaroslav@1646: *
JVM Specification, 5.4.4 "Access Control"
jaroslav@1646: * A field or method R is accessible to a class or interface D if
jaroslav@1646: * and only if any of the following conditions is true:
jaroslav@1646: * - R is public.
jaroslav@1646: *
- R is protected and is declared in a class C, and D is either
jaroslav@1646: * a subclass of C or C itself. Furthermore, if R is not
jaroslav@1646: * static, then the symbolic reference to R must contain a
jaroslav@1646: * symbolic reference to a class T, such that T is either a
jaroslav@1646: * subclass of D, a superclass of D or D itself.
jaroslav@1646: *
- R is either protected or has default access (that is,
jaroslav@1646: * neither public nor protected nor private), and is declared
jaroslav@1646: * by a class in the same runtime package as D.
jaroslav@1646: *
- R is private and is declared in D.
jaroslav@1646: *
jaroslav@1646: * This discussion of access control omits a related restriction
jaroslav@1646: * on the target of a protected field access or method invocation
jaroslav@1646: * (the target must be of class D or a subtype of D). That
jaroslav@1646: * requirement is checked as part of the verification process
jaroslav@1646: * (5.4.1); it is not part of link-time access control.
jaroslav@1646: * @param refc the class used in the symbolic reference to the proposed member
jaroslav@1646: * @param defc the class in which the proposed member is actually defined
jaroslav@1646: * @param mods modifier flags for the proposed member
jaroslav@1646: * @param lookupClass the class for which the access check is being made
jaroslav@1646: * @return true iff the the accessing class can access such a member
jaroslav@1646: */
jaroslav@1646: public static boolean isMemberAccessible(Class> refc, // symbolic ref class
jaroslav@1646: Class> defc, // actual def class
jaroslav@1646: int mods, // actual member mods
jaroslav@1646: Class> lookupClass,
jaroslav@1646: int allowedModes) {
jaroslav@1646: if (allowedModes == 0) return false;
jaroslav@1646: assert((allowedModes & PUBLIC) != 0 &&
jaroslav@1646: (allowedModes & ~(ALL_ACCESS_MODES|PACKAGE_ALLOWED)) == 0);
jaroslav@1646: // The symbolic reference class (refc) must always be fully verified.
jaroslav@1646: if (!isClassAccessible(refc, lookupClass, allowedModes)) {
jaroslav@1646: return false;
jaroslav@1646: }
jaroslav@1646: // Usually refc and defc are the same, but verify defc also in case they differ.
jaroslav@1646: if (defc == lookupClass &&
jaroslav@1646: (allowedModes & PRIVATE) != 0)
jaroslav@1646: return true; // easy check; all self-access is OK
jaroslav@1646: switch (mods & ALL_ACCESS_MODES) {
jaroslav@1646: case PUBLIC:
jaroslav@1646: return true; // already checked above
jaroslav@1646: case PROTECTED:
jaroslav@1646: if ((allowedModes & PROTECTED_OR_PACKAGE_ALLOWED) != 0 &&
jaroslav@1646: isSamePackage(defc, lookupClass))
jaroslav@1646: return true;
jaroslav@1646: if ((allowedModes & PROTECTED) == 0)
jaroslav@1646: return false;
jaroslav@1646: if ((mods & STATIC) != 0 &&
jaroslav@1646: !isRelatedClass(refc, lookupClass))
jaroslav@1646: return false;
jaroslav@1646: if ((allowedModes & PROTECTED) != 0 &&
jaroslav@1646: isSuperClass(defc, lookupClass))
jaroslav@1646: return true;
jaroslav@1646: return false;
jaroslav@1646: case PACKAGE_ONLY: // That is, zero. Unmarked member is package-only access.
jaroslav@1646: return ((allowedModes & PACKAGE_ALLOWED) != 0 &&
jaroslav@1646: isSamePackage(defc, lookupClass));
jaroslav@1646: case PRIVATE:
jaroslav@1646: // Loosened rules for privates follows access rules for inner classes.
jaroslav@1646: return (ALLOW_NESTMATE_ACCESS &&
jaroslav@1646: (allowedModes & PRIVATE) != 0 &&
jaroslav@1646: isSamePackageMember(defc, lookupClass));
jaroslav@1646: default:
jaroslav@1646: throw new IllegalArgumentException("bad modifiers: "+Modifier.toString(mods));
jaroslav@1646: }
jaroslav@1646: }
jaroslav@1646:
jaroslav@1646: static boolean isRelatedClass(Class> refc, Class> lookupClass) {
jaroslav@1646: return (refc == lookupClass ||
jaroslav@1646: refc.isAssignableFrom(lookupClass) ||
jaroslav@1646: lookupClass.isAssignableFrom(refc));
jaroslav@1646: }
jaroslav@1646:
jaroslav@1646: static boolean isSuperClass(Class> defc, Class> lookupClass) {
jaroslav@1646: return defc.isAssignableFrom(lookupClass);
jaroslav@1646: }
jaroslav@1646:
jaroslav@1646: static int getClassModifiers(Class> c) {
jaroslav@1646: // This would return the mask stored by javac for the source-level modifiers.
jaroslav@1646: // return c.getModifiers();
jaroslav@1646: // But what we need for JVM access checks are the actual bits from the class header.
jaroslav@1646: // ...But arrays and primitives are synthesized with their own odd flags:
jaroslav@1646: if (c.isArray() || c.isPrimitive())
jaroslav@1646: return c.getModifiers();
jaroslav@1646: return Reflection.getClassAccessFlags(c);
jaroslav@1646: }
jaroslav@1646:
jaroslav@1646: /**
jaroslav@1646: * Evaluate the JVM linkage rules for access to the given class on behalf of caller.
jaroslav@1646: * JVM Specification, 5.4.4 "Access Control"
jaroslav@1646: * A class or interface C is accessible to a class or interface D
jaroslav@1646: * if and only if either of the following conditions are true:
jaroslav@1646: * - C is public.
jaroslav@1646: *
- C and D are members of the same runtime package.
jaroslav@1646: *
jaroslav@1646: * @param refc the symbolic reference class to which access is being checked (C)
jaroslav@1646: * @param lookupClass the class performing the lookup (D)
jaroslav@1646: */
jaroslav@1646: public static boolean isClassAccessible(Class> refc, Class> lookupClass,
jaroslav@1646: int allowedModes) {
jaroslav@1646: if (allowedModes == 0) return false;
jaroslav@1646: assert((allowedModes & PUBLIC) != 0 &&
jaroslav@1646: (allowedModes & ~(ALL_ACCESS_MODES|PACKAGE_ALLOWED)) == 0);
jaroslav@1646: int mods = getClassModifiers(refc);
jaroslav@1646: if (isPublic(mods))
jaroslav@1646: return true;
jaroslav@1646: if ((allowedModes & PACKAGE_ALLOWED) != 0 &&
jaroslav@1646: isSamePackage(lookupClass, refc))
jaroslav@1646: return true;
jaroslav@1646: return false;
jaroslav@1646: }
jaroslav@1646:
jaroslav@1646: /**
jaroslav@1646: * Decide if the given method type, attributed to a member or symbolic
jaroslav@1646: * reference of a given reference class, is really visible to that class.
jaroslav@1646: * @param type the supposed type of a member or symbolic reference of refc
jaroslav@1646: * @param refc the class attempting to make the reference
jaroslav@1646: */
jaroslav@1646: public static boolean isTypeVisible(Class> type, Class> refc) {
jaroslav@1646: if (type == refc) return true; // easy check
jaroslav@1646: while (type.isArray()) type = type.getComponentType();
jaroslav@1646: if (type.isPrimitive() || type == Object.class) return true;
jaroslav@1646: ClassLoader parent = type.getClassLoader();
jaroslav@1646: if (parent == null) return true;
jaroslav@1646: ClassLoader child = refc.getClassLoader();
jaroslav@1646: if (child == null) return false;
jaroslav@1646: if (parent == child || loadersAreRelated(parent, child, true))
jaroslav@1646: return true;
jaroslav@1646: // Do it the hard way: Look up the type name from the refc loader.
jaroslav@1646: try {
jaroslav@1646: Class> res = child.loadClass(type.getName());
jaroslav@1646: return (type == res);
jaroslav@1646: } catch (ClassNotFoundException ex) {
jaroslav@1646: return false;
jaroslav@1646: }
jaroslav@1646: }
jaroslav@1646:
jaroslav@1646: /**
jaroslav@1646: * Decide if the given method type, attributed to a member or symbolic
jaroslav@1646: * reference of a given reference class, is really visible to that class.
jaroslav@1646: * @param type the supposed type of a member or symbolic reference of refc
jaroslav@1646: * @param refc the class attempting to make the reference
jaroslav@1646: */
jaroslav@1646: public static boolean isTypeVisible(java.lang.invoke.MethodType type, Class> refc) {
jaroslav@1646: for (int n = -1, max = type.parameterCount(); n < max; n++) {
jaroslav@1646: Class> ptype = (n < 0 ? type.returnType() : type.parameterType(n));
jaroslav@1646: if (!isTypeVisible(ptype, refc))
jaroslav@1646: return false;
jaroslav@1646: }
jaroslav@1646: return true;
jaroslav@1646: }
jaroslav@1646:
jaroslav@1646: /**
jaroslav@1646: * Test if two classes have the same class loader and package qualifier.
jaroslav@1646: * @param class1 a class
jaroslav@1646: * @param class2 another class
jaroslav@1646: * @return whether they are in the same package
jaroslav@1646: */
jaroslav@1646: public static boolean isSamePackage(Class> class1, Class> class2) {
jaroslav@1646: assert(!class1.isArray() && !class2.isArray());
jaroslav@1646: if (class1 == class2)
jaroslav@1646: return true;
jaroslav@1646: if (class1.getClassLoader() != class2.getClassLoader())
jaroslav@1646: return false;
jaroslav@1646: String name1 = class1.getName(), name2 = class2.getName();
jaroslav@1646: int dot = name1.lastIndexOf('.');
jaroslav@1646: if (dot != name2.lastIndexOf('.'))
jaroslav@1646: return false;
jaroslav@1646: for (int i = 0; i < dot; i++) {
jaroslav@1646: if (name1.charAt(i) != name2.charAt(i))
jaroslav@1646: return false;
jaroslav@1646: }
jaroslav@1646: return true;
jaroslav@1646: }
jaroslav@1646:
jaroslav@1646: /** Return the package name for this class.
jaroslav@1646: */
jaroslav@1646: public static String getPackageName(Class> cls) {
jaroslav@1646: assert(!cls.isArray());
jaroslav@1646: String name = cls.getName();
jaroslav@1646: int dot = name.lastIndexOf('.');
jaroslav@1646: if (dot < 0) return "";
jaroslav@1646: return name.substring(0, dot);
jaroslav@1646: }
jaroslav@1646:
jaroslav@1646: /**
jaroslav@1646: * Test if two classes are defined as part of the same package member (top-level class).
jaroslav@1646: * If this is true, they can share private access with each other.
jaroslav@1646: * @param class1 a class
jaroslav@1646: * @param class2 another class
jaroslav@1646: * @return whether they are identical or nested together
jaroslav@1646: */
jaroslav@1646: public static boolean isSamePackageMember(Class> class1, Class> class2) {
jaroslav@1646: if (class1 == class2)
jaroslav@1646: return true;
jaroslav@1646: if (!isSamePackage(class1, class2))
jaroslav@1646: return false;
jaroslav@1646: if (getOutermostEnclosingClass(class1) != getOutermostEnclosingClass(class2))
jaroslav@1646: return false;
jaroslav@1646: return true;
jaroslav@1646: }
jaroslav@1646:
jaroslav@1646: private static Class> getOutermostEnclosingClass(Class> c) {
jaroslav@1646: Class> pkgmem = c;
jaroslav@1646: for (Class> enc = c; (enc = enc.getEnclosingClass()) != null; )
jaroslav@1646: pkgmem = enc;
jaroslav@1646: return pkgmem;
jaroslav@1646: }
jaroslav@1646:
jaroslav@1646: private static boolean loadersAreRelated(ClassLoader loader1, ClassLoader loader2,
jaroslav@1646: boolean loader1MustBeParent) {
jaroslav@1646: if (loader1 == loader2 || loader1 == null
jaroslav@1646: || (loader2 == null && !loader1MustBeParent)) {
jaroslav@1646: return true;
jaroslav@1646: }
jaroslav@1646: for (ClassLoader scan2 = loader2;
jaroslav@1646: scan2 != null; scan2 = scan2.getParent()) {
jaroslav@1646: if (scan2 == loader1) return true;
jaroslav@1646: }
jaroslav@1646: if (loader1MustBeParent) return false;
jaroslav@1646: // see if loader2 is a parent of loader1:
jaroslav@1646: for (ClassLoader scan1 = loader1;
jaroslav@1646: scan1 != null; scan1 = scan1.getParent()) {
jaroslav@1646: if (scan1 == loader2) return true;
jaroslav@1646: }
jaroslav@1646: return false;
jaroslav@1646: }
jaroslav@1646:
jaroslav@1646: /**
jaroslav@1646: * Is the class loader of parentClass identical to, or an ancestor of,
jaroslav@1646: * the class loader of childClass?
jaroslav@1646: * @param parentClass a class
jaroslav@1646: * @param childClass another class, which may be a descendent of the first class
jaroslav@1646: * @return whether parentClass precedes or equals childClass in class loader order
jaroslav@1646: */
jaroslav@1646: public static boolean classLoaderIsAncestor(Class> parentClass, Class> childClass) {
jaroslav@1646: return loadersAreRelated(parentClass.getClassLoader(), childClass.getClassLoader(), true);
jaroslav@1646: }
jaroslav@1646: }