diff -r 000000000000 -r c880a8a8803b rt/emul/compact/src/main/java/sun/invoke/util/VerifyAccess.java --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/rt/emul/compact/src/main/java/sun/invoke/util/VerifyAccess.java Sat Aug 09 11:11:13 2014 +0200 @@ -0,0 +1,301 @@ +/* + * Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. Oracle designates this + * particular file as subject to the "Classpath" exception as provided + * by Oracle in the LICENSE file that accompanied this code. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + */ + +package sun.invoke.util; + +import java.lang.reflect.Modifier; +import static java.lang.reflect.Modifier.*; +import sun.reflect.Reflection; + +/** + * This class centralizes information about the JVM's linkage access control. + * @author jrose + */ +public class VerifyAccess { + + private VerifyAccess() { } // cannot instantiate + + private static final int PACKAGE_ONLY = 0; + private static final int PACKAGE_ALLOWED = java.lang.invoke.MethodHandles.Lookup.PACKAGE; + private static final int PROTECTED_OR_PACKAGE_ALLOWED = (PACKAGE_ALLOWED|PROTECTED); + private static final int ALL_ACCESS_MODES = (PUBLIC|PRIVATE|PROTECTED|PACKAGE_ONLY); + private static final boolean ALLOW_NESTMATE_ACCESS = false; + + /** + * Evaluate the JVM linkage rules for access to the given method + * on behalf of a caller class which proposes to perform the access. + * Return true if the caller class has privileges to invoke a method + * or access a field with the given properties. + * This requires an accessibility check of the referencing class, + * plus an accessibility check of the member within the class, + * which depends on the member's modifier flags. + *

+ * The relevant properties include the defining class ({@code defc}) + * of the member, and its modifier flags ({@code mods}). + * Also relevant is the class used to make the initial symbolic reference + * to the member ({@code refc}). If this latter class is not distinguished, + * the defining class should be passed for both arguments ({@code defc == refc}). + *

JVM Specification, 5.4.4 "Access Control"

+ * A field or method R is accessible to a class or interface D if + * and only if any of the following conditions is true: + * This discussion of access control omits a related restriction + * on the target of a protected field access or method invocation + * (the target must be of class D or a subtype of D). That + * requirement is checked as part of the verification process + * (5.4.1); it is not part of link-time access control. + * @param refc the class used in the symbolic reference to the proposed member + * @param defc the class in which the proposed member is actually defined + * @param mods modifier flags for the proposed member + * @param lookupClass the class for which the access check is being made + * @return true iff the the accessing class can access such a member + */ + public static boolean isMemberAccessible(Class refc, // symbolic ref class + Class defc, // actual def class + int mods, // actual member mods + Class lookupClass, + int allowedModes) { + if (allowedModes == 0) return false; + assert((allowedModes & PUBLIC) != 0 && + (allowedModes & ~(ALL_ACCESS_MODES|PACKAGE_ALLOWED)) == 0); + // The symbolic reference class (refc) must always be fully verified. + if (!isClassAccessible(refc, lookupClass, allowedModes)) { + return false; + } + // Usually refc and defc are the same, but verify defc also in case they differ. + if (defc == lookupClass && + (allowedModes & PRIVATE) != 0) + return true; // easy check; all self-access is OK + switch (mods & ALL_ACCESS_MODES) { + case PUBLIC: + return true; // already checked above + case PROTECTED: + if ((allowedModes & PROTECTED_OR_PACKAGE_ALLOWED) != 0 && + isSamePackage(defc, lookupClass)) + return true; + if ((allowedModes & PROTECTED) == 0) + return false; + if ((mods & STATIC) != 0 && + !isRelatedClass(refc, lookupClass)) + return false; + if ((allowedModes & PROTECTED) != 0 && + isSuperClass(defc, lookupClass)) + return true; + return false; + case PACKAGE_ONLY: // That is, zero. Unmarked member is package-only access. + return ((allowedModes & PACKAGE_ALLOWED) != 0 && + isSamePackage(defc, lookupClass)); + case PRIVATE: + // Loosened rules for privates follows access rules for inner classes. + return (ALLOW_NESTMATE_ACCESS && + (allowedModes & PRIVATE) != 0 && + isSamePackageMember(defc, lookupClass)); + default: + throw new IllegalArgumentException("bad modifiers: "+Modifier.toString(mods)); + } + } + + static boolean isRelatedClass(Class refc, Class lookupClass) { + return (refc == lookupClass || + refc.isAssignableFrom(lookupClass) || + lookupClass.isAssignableFrom(refc)); + } + + static boolean isSuperClass(Class defc, Class lookupClass) { + return defc.isAssignableFrom(lookupClass); + } + + static int getClassModifiers(Class c) { + // This would return the mask stored by javac for the source-level modifiers. + // return c.getModifiers(); + // But what we need for JVM access checks are the actual bits from the class header. + // ...But arrays and primitives are synthesized with their own odd flags: + if (c.isArray() || c.isPrimitive()) + return c.getModifiers(); + return Reflection.getClassAccessFlags(c); + } + + /** + * Evaluate the JVM linkage rules for access to the given class on behalf of caller. + *

JVM Specification, 5.4.4 "Access Control"

+ * A class or interface C is accessible to a class or interface D + * if and only if either of the following conditions are true: + * @param refc the symbolic reference class to which access is being checked (C) + * @param lookupClass the class performing the lookup (D) + */ + public static boolean isClassAccessible(Class refc, Class lookupClass, + int allowedModes) { + if (allowedModes == 0) return false; + assert((allowedModes & PUBLIC) != 0 && + (allowedModes & ~(ALL_ACCESS_MODES|PACKAGE_ALLOWED)) == 0); + int mods = getClassModifiers(refc); + if (isPublic(mods)) + return true; + if ((allowedModes & PACKAGE_ALLOWED) != 0 && + isSamePackage(lookupClass, refc)) + return true; + return false; + } + + /** + * Decide if the given method type, attributed to a member or symbolic + * reference of a given reference class, is really visible to that class. + * @param type the supposed type of a member or symbolic reference of refc + * @param refc the class attempting to make the reference + */ + public static boolean isTypeVisible(Class type, Class refc) { + if (type == refc) return true; // easy check + while (type.isArray()) type = type.getComponentType(); + if (type.isPrimitive() || type == Object.class) return true; + ClassLoader parent = type.getClassLoader(); + if (parent == null) return true; + ClassLoader child = refc.getClassLoader(); + if (child == null) return false; + if (parent == child || loadersAreRelated(parent, child, true)) + return true; + // Do it the hard way: Look up the type name from the refc loader. + try { + Class res = child.loadClass(type.getName()); + return (type == res); + } catch (ClassNotFoundException ex) { + return false; + } + } + + /** + * Decide if the given method type, attributed to a member or symbolic + * reference of a given reference class, is really visible to that class. + * @param type the supposed type of a member or symbolic reference of refc + * @param refc the class attempting to make the reference + */ + public static boolean isTypeVisible(java.lang.invoke.MethodType type, Class refc) { + for (int n = -1, max = type.parameterCount(); n < max; n++) { + Class ptype = (n < 0 ? type.returnType() : type.parameterType(n)); + if (!isTypeVisible(ptype, refc)) + return false; + } + return true; + } + + /** + * Test if two classes have the same class loader and package qualifier. + * @param class1 a class + * @param class2 another class + * @return whether they are in the same package + */ + public static boolean isSamePackage(Class class1, Class class2) { + assert(!class1.isArray() && !class2.isArray()); + if (class1 == class2) + return true; + if (class1.getClassLoader() != class2.getClassLoader()) + return false; + String name1 = class1.getName(), name2 = class2.getName(); + int dot = name1.lastIndexOf('.'); + if (dot != name2.lastIndexOf('.')) + return false; + for (int i = 0; i < dot; i++) { + if (name1.charAt(i) != name2.charAt(i)) + return false; + } + return true; + } + + /** Return the package name for this class. + */ + public static String getPackageName(Class cls) { + assert(!cls.isArray()); + String name = cls.getName(); + int dot = name.lastIndexOf('.'); + if (dot < 0) return ""; + return name.substring(0, dot); + } + + /** + * Test if two classes are defined as part of the same package member (top-level class). + * If this is true, they can share private access with each other. + * @param class1 a class + * @param class2 another class + * @return whether they are identical or nested together + */ + public static boolean isSamePackageMember(Class class1, Class class2) { + if (class1 == class2) + return true; + if (!isSamePackage(class1, class2)) + return false; + if (getOutermostEnclosingClass(class1) != getOutermostEnclosingClass(class2)) + return false; + return true; + } + + private static Class getOutermostEnclosingClass(Class c) { + Class pkgmem = c; + for (Class enc = c; (enc = enc.getEnclosingClass()) != null; ) + pkgmem = enc; + return pkgmem; + } + + private static boolean loadersAreRelated(ClassLoader loader1, ClassLoader loader2, + boolean loader1MustBeParent) { + if (loader1 == loader2 || loader1 == null + || (loader2 == null && !loader1MustBeParent)) { + return true; + } + for (ClassLoader scan2 = loader2; + scan2 != null; scan2 = scan2.getParent()) { + if (scan2 == loader1) return true; + } + if (loader1MustBeParent) return false; + // see if loader2 is a parent of loader1: + for (ClassLoader scan1 = loader1; + scan1 != null; scan1 = scan1.getParent()) { + if (scan1 == loader2) return true; + } + return false; + } + + /** + * Is the class loader of parentClass identical to, or an ancestor of, + * the class loader of childClass? + * @param parentClass a class + * @param childClass another class, which may be a descendent of the first class + * @return whether parentClass precedes or equals childClass in class loader order + */ + public static boolean classLoaderIsAncestor(Class parentClass, Class childClass) { + return loadersAreRelated(parentClass.getClassLoader(), childClass.getClassLoader(), true); + } +}