Java tutorial
/* * Copyright (c) 1997, 2015, 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 java.util; import java.io.IOException; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.io.ObjectStreamField; import java.io.Serializable; import java.security.*; import java.util.Enumeration; import java.util.Hashtable; import java.util.concurrent.ConcurrentHashMap; import sun.security.util.SecurityConstants; /** * This class is for property permissions. * * <P> * The name is the name of the property ("java.home", * "os.name", etc). The naming * convention follows the hierarchical property naming convention. * Also, an asterisk * may appear at the end of the name, following a ".", or by itself, to * signify a wildcard match. For example: "java.*" and "*" signify a wildcard * match, while "*java" and "a*b" do not. * <P> * The actions to be granted are passed to the constructor in a string containing * a list of one or more comma-separated keywords. The possible keywords are * "read" and "write". Their meaning is defined as follows: * * <DL> * <DT> read * <DD> read permission. Allows <code>System.getProperty</code> to * be called. * <DT> write * <DD> write permission. Allows <code>System.setProperty</code> to * be called. * </DL> * <P> * The actions string is converted to lowercase before processing. * <P> * Care should be taken before granting code permission to access * certain system properties. For example, granting permission to * access the "java.home" system property gives potentially malevolent * code sensitive information about the system environment (the Java * installation directory). Also, granting permission to access * the "user.name" and "user.home" system properties gives potentially * malevolent code sensitive information about the user environment * (the user's account name and home directory). * * @see java.security.BasicPermission * @see java.security.Permission * @see java.security.Permissions * @see java.security.PermissionCollection * @see java.lang.SecurityManager * * * @author Roland Schemers * @since 1.2 * * @serial exclude */ public final class PropertyPermission extends BasicPermission { /** * Read action. */ private static final int READ = 0x1; /** * Write action. */ private static final int WRITE = 0x2; /** * All actions (read,write); */ private static final int ALL = READ | WRITE; /** * No actions. */ private static final int NONE = 0x0; /** * The actions mask. * */ private transient int mask; /** * The actions string. * * @serial */ private String actions; // Left null as long as possible, then // created and re-used in the getAction function. /** * initialize a PropertyPermission object. Common to all constructors. * Also called during de-serialization. * * @param mask the actions mask to use. * */ private void init(int mask) { if ((mask & ALL) != mask) throw new IllegalArgumentException("invalid actions mask"); if (mask == NONE) throw new IllegalArgumentException("invalid actions mask"); if (getName() == null) throw new NullPointerException("name can't be null"); this.mask = mask; } /** * Creates a new PropertyPermission object with the specified name. * The name is the name of the system property, and * <i>actions</i> contains a comma-separated list of the * desired actions granted on the property. Possible actions are * "read" and "write". * * @param name the name of the PropertyPermission. * @param actions the actions string. * * @throws NullPointerException if <code>name</code> is <code>null</code>. * @throws IllegalArgumentException if <code>name</code> is empty or if * <code>actions</code> is invalid. */ public PropertyPermission(String name, String actions) { super(name, actions); init(getMask(actions)); } /** * Creates a PropertyPermission object with the specified name and * a pre-calculated mask. Avoids the overhead of re-computing the mask. * Called by PropertyPermissionCollection. */ PropertyPermission(String name, int mask) { super(name, getActions(mask)); this.mask = mask; } /** * Checks if this PropertyPermission object "implies" the specified * permission. * <P> * More specifically, this method returns true if: * <ul> * <li> <i>p</i> is an instanceof PropertyPermission, * <li> <i>p</i>'s actions are a subset of this * object's actions, and * <li> <i>p</i>'s name is implied by this object's * name. For example, "java.*" implies "java.home". * </ul> * @param p the permission to check against. * * @return true if the specified permission is implied by this object, * false if not. */ @Override public boolean implies(Permission p) { if (!(p instanceof PropertyPermission)) return false; PropertyPermission that = (PropertyPermission) p; // we get the effective mask. i.e., the "and" of this and that. // They must be equal to that.mask for implies to return true. return ((this.mask & that.mask) == that.mask) && super.implies(that); } /** * Checks two PropertyPermission objects for equality. Checks that <i>obj</i> is * a PropertyPermission, and has the same name and actions as this object. * * @param obj the object we are testing for equality with this object. * @return true if obj is a PropertyPermission, and has the same name and * actions as this PropertyPermission object. */ @Override public boolean equals(Object obj) { if (obj == this) return true; if (!(obj instanceof PropertyPermission)) return false; PropertyPermission that = (PropertyPermission) obj; return (this.mask == that.mask) && (this.getName().equals(that.getName())); } /** * Returns the hash code value for this object. * The hash code used is the hash code of this permissions name, that is, * <code>getName().hashCode()</code>, where <code>getName</code> is * from the Permission superclass. * * @return a hash code value for this object. */ @Override public int hashCode() { return this.getName().hashCode(); } /** * Converts an actions String to an actions mask. * * @param actions the action string. * @return the actions mask. */ private static int getMask(String actions) { int mask = NONE; if (actions == null) { return mask; } // Use object identity comparison against known-interned strings for // performance benefit (these values are used heavily within the JDK). if (actions == SecurityConstants.PROPERTY_READ_ACTION) { return READ; } if (actions == SecurityConstants.PROPERTY_WRITE_ACTION) { return WRITE; } else if (actions == SecurityConstants.PROPERTY_RW_ACTION) { return READ | WRITE; } char[] a = actions.toCharArray(); int i = a.length - 1; if (i < 0) return mask; while (i != -1) { char c; // skip whitespace while ((i != -1) && ((c = a[i]) == ' ' || c == '\r' || c == '\n' || c == '\f' || c == '\t')) i--; // check for the known strings int matchlen; if (i >= 3 && (a[i - 3] == 'r' || a[i - 3] == 'R') && (a[i - 2] == 'e' || a[i - 2] == 'E') && (a[i - 1] == 'a' || a[i - 1] == 'A') && (a[i] == 'd' || a[i] == 'D')) { matchlen = 4; mask |= READ; } else if (i >= 4 && (a[i - 4] == 'w' || a[i - 4] == 'W') && (a[i - 3] == 'r' || a[i - 3] == 'R') && (a[i - 2] == 'i' || a[i - 2] == 'I') && (a[i - 1] == 't' || a[i - 1] == 'T') && (a[i] == 'e' || a[i] == 'E')) { matchlen = 5; mask |= WRITE; } else { // parse error throw new IllegalArgumentException("invalid permission: " + actions); } // make sure we didn't just match the tail of a word // like "ackbarfaccept". Also, skip to the comma. boolean seencomma = false; while (i >= matchlen && !seencomma) { switch (a[i - matchlen]) { case ',': seencomma = true; break; case ' ': case '\r': case '\n': case '\f': case '\t': break; default: throw new IllegalArgumentException("invalid permission: " + actions); } i--; } // point i at the location of the comma minus one (or -1). i -= matchlen; } return mask; } /** * Return the canonical string representation of the actions. * Always returns present actions in the following order: * read, write. * * @return the canonical string representation of the actions. */ static String getActions(int mask) { switch (mask & (READ | WRITE)) { case READ: return SecurityConstants.PROPERTY_READ_ACTION; case WRITE: return SecurityConstants.PROPERTY_WRITE_ACTION; case READ | WRITE: return SecurityConstants.PROPERTY_RW_ACTION; default: return ""; } } /** * Returns the "canonical string representation" of the actions. * That is, this method always returns present actions in the following order: * read, write. For example, if this PropertyPermission object * allows both write and read actions, a call to <code>getActions</code> * will return the string "read,write". * * @return the canonical string representation of the actions. */ @Override public String getActions() { if (actions == null) actions = getActions(this.mask); return actions; } /** * Return the current action mask. * Used by the PropertyPermissionCollection * * @return the actions mask. */ int getMask() { return mask; } /** * Returns a new PermissionCollection object for storing * PropertyPermission objects. * * @return a new PermissionCollection object suitable for storing * PropertyPermissions. */ @Override public PermissionCollection newPermissionCollection() { return new PropertyPermissionCollection(); } private static final long serialVersionUID = 885438825399942851L; /** * WriteObject is called to save the state of the PropertyPermission * to a stream. The actions are serialized, and the superclass * takes care of the name. */ private synchronized void writeObject(java.io.ObjectOutputStream s) throws IOException { // Write out the actions. The superclass takes care of the name // call getActions to make sure actions field is initialized if (actions == null) getActions(); s.defaultWriteObject(); } /** * readObject is called to restore the state of the PropertyPermission from * a stream. */ private synchronized void readObject(java.io.ObjectInputStream s) throws IOException, ClassNotFoundException { // Read in the action, then initialize the rest s.defaultReadObject(); init(getMask(actions)); } } /** * A PropertyPermissionCollection stores a set of PropertyPermission * permissions. * * @see java.security.Permission * @see java.security.Permissions * @see java.security.PermissionCollection * * * @author Roland Schemers * * @serial include */ final class PropertyPermissionCollection extends PermissionCollection implements Serializable { /** * Key is property name; value is PropertyPermission. * Not serialized; see serialization section at end of class. */ private transient ConcurrentHashMap<String, PropertyPermission> perms; /** * Boolean saying if "*" is in the collection. * * @see #serialPersistentFields */ // No sync access; OK for this to be stale. private boolean all_allowed; /** * Create an empty PropertyPermissionCollection object. */ public PropertyPermissionCollection() { perms = new ConcurrentHashMap<>(32); // Capacity for default policy all_allowed = false; } /** * Adds a permission to the PropertyPermissions. The key for the hash is * the name. * * @param permission the Permission object to add. * * @exception IllegalArgumentException - if the permission is not a * PropertyPermission * * @exception SecurityException - if this PropertyPermissionCollection * object has been marked readonly */ @Override public void add(Permission permission) { if (!(permission instanceof PropertyPermission)) throw new IllegalArgumentException("invalid permission: " + permission); if (isReadOnly()) throw new SecurityException("attempt to add a Permission to a readonly PermissionCollection"); PropertyPermission pp = (PropertyPermission) permission; String propName = pp.getName(); // Add permission to map if it is absent, or replace with new // permission if applicable. NOTE: cannot use lambda for // remappingFunction parameter until JDK-8076596 is fixed. perms.merge(propName, pp, new java.util.function.BiFunction<>() { @Override public PropertyPermission apply(PropertyPermission existingVal, PropertyPermission newVal) { int oldMask = existingVal.getMask(); int newMask = newVal.getMask(); if (oldMask != newMask) { int effective = oldMask | newMask; if (effective == newMask) { return newVal; } if (effective != oldMask) { return new PropertyPermission(propName, effective); } } return existingVal; } }); if (!all_allowed) { if (propName.equals("*")) all_allowed = true; } } /** * Check and see if this set of permissions implies the permissions * expressed in "permission". * * @param permission the Permission object to compare * * @return true if "permission" is a proper subset of a permission in * the set, false if not. */ @Override public boolean implies(Permission permission) { if (!(permission instanceof PropertyPermission)) return false; PropertyPermission pp = (PropertyPermission) permission; PropertyPermission x; int desired = pp.getMask(); int effective = 0; // short circuit if the "*" Permission was added if (all_allowed) { x = perms.get("*"); if (x != null) { effective |= x.getMask(); if ((effective & desired) == desired) return true; } } // strategy: // Check for full match first. Then work our way up the // name looking for matches on a.b.* String name = pp.getName(); //System.out.println("check "+name); x = perms.get(name); if (x != null) { // we have a direct hit! effective |= x.getMask(); if ((effective & desired) == desired) return true; } // work our way up the tree... int last, offset; offset = name.length() - 1; while ((last = name.lastIndexOf('.', offset)) != -1) { name = name.substring(0, last + 1) + "*"; //System.out.println("check "+name); x = perms.get(name); if (x != null) { effective |= x.getMask(); if ((effective & desired) == desired) return true; } offset = last - 1; } // we don't have to check for "*" as it was already checked // at the top (all_allowed), so we just return false return false; } /** * Returns an enumeration of all the PropertyPermission objects in the * container. * * @return an enumeration of all the PropertyPermission objects. */ @Override @SuppressWarnings("unchecked") public Enumeration<Permission> elements() { /** * Casting to rawtype since Enumeration<PropertyPermission> * cannot be directly cast to Enumeration<Permission> */ return (Enumeration) perms.elements(); } private static final long serialVersionUID = 7015263904581634791L; // Need to maintain serialization interoperability with earlier releases, // which had the serializable field: // // Table of permissions. // // @serial // // private Hashtable permissions; /** * @serialField permissions java.util.Hashtable * A table of the PropertyPermissions. * @serialField all_allowed boolean * boolean saying if "*" is in the collection. */ private static final ObjectStreamField[] serialPersistentFields = { new ObjectStreamField("permissions", Hashtable.class), new ObjectStreamField("all_allowed", Boolean.TYPE), }; /** * @serialData Default fields. */ /* * Writes the contents of the perms field out as a Hashtable for * serialization compatibility with earlier releases. all_allowed * unchanged. */ private void writeObject(ObjectOutputStream out) throws IOException { // Don't call out.defaultWriteObject() // Copy perms into a Hashtable Hashtable<String, Permission> permissions = new Hashtable<>(perms.size() * 2); permissions.putAll(perms); // Write out serializable fields ObjectOutputStream.PutField pfields = out.putFields(); pfields.put("all_allowed", all_allowed); pfields.put("permissions", permissions); out.writeFields(); } /* * Reads in a Hashtable of PropertyPermissions and saves them in the * perms field. Reads in all_allowed. */ private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException { // Don't call defaultReadObject() // Read in serialized fields ObjectInputStream.GetField gfields = in.readFields(); // Get all_allowed all_allowed = gfields.get("all_allowed", false); // Get permissions @SuppressWarnings("unchecked") Hashtable<String, PropertyPermission> permissions = (Hashtable<String, PropertyPermission>) gfields .get("permissions", null); perms = new ConcurrentHashMap<>(permissions.size() * 2); perms.putAll(permissions); } }