src/java.xml/share/classes/com/sun/org/apache/xerces/internal/util/SecurityManager.java

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 * Licensed to the Apache Software Foundation (ASF) under one or more
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 * this work for additional information regarding copyright ownership.
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 * (the "License"); you may not use this file except in compliance with
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 *      http://www.apache.org/licenses/LICENSE-2.0
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package com.sun.org.apache.xerces.internal.util;
import com.sun.org.apache.xerces.internal.impl.Constants;
/**
 * This class is a container for parser settings that relate to
 * security, or more specifically, it is intended to be used to prevent denial-of-service
 * attacks from being launched against a system running Xerces.
 * Any component that is aware of a denial-of-service attack that can arise
 * from its processing of a certain kind of document may query its Component Manager
 * for the property (http://apache.org/xml/properties/security-manager)
 * whose value will be an instance of this class.
 * If no value has been set for the property, the component should proceed in the "usual" (spec-compliant)
 * manner.  If a value has been set, then it must be the case that the component in
 * question needs to know what method of this class to query.  This class
 * will provide defaults for all known security issues, but will also provide
 * setters so that those values can be tailored by applications that care.
 *
 * @author  Neil Graham, IBM
 *
 */
public final class SecurityManager {

    //
    // Constants
    //

    // default value for entity expansion limit
    private final static int DEFAULT_ENTITY_EXPANSION_LIMIT = 64000;

    /** Default value of number of nodes created. **/
    private final static int DEFAULT_MAX_OCCUR_NODE_LIMIT = 5000;

    //
    // Data
    //

        private final static int DEFAULT_ELEMENT_ATTRIBUTE_LIMIT = 10000;

    /** Entity expansion limit. **/
    private int entityExpansionLimit;

    /** W3C XML Schema maxOccurs limit. **/
    private int maxOccurLimit;

        private int fElementAttributeLimit;
    // default constructor.  Establishes default values for
    // all known security holes.
    /**
     * Default constructor.  Establishes default values
     * for known security vulnerabilities.
     */
    public SecurityManager() {
        entityExpansionLimit = DEFAULT_ENTITY_EXPANSION_LIMIT;
        maxOccurLimit = DEFAULT_MAX_OCCUR_NODE_LIMIT ;
                fElementAttributeLimit = DEFAULT_ELEMENT_ATTRIBUTE_LIMIT;
                //We are reading system properties only once ,
                //at the time of creation of this object ,
                readSystemProperties();
    }

    /**
     * <p>Sets the number of entity expansions that the
     * parser should permit in a document.</p>
     *
     * @param limit the number of entity expansions
     * permitted in a document
     */
    public void setEntityExpansionLimit(int limit) {
        entityExpansionLimit = limit;
    }

    /**
     * <p>Returns the number of entity expansions
     * that the parser permits in a document.</p>
     *
     * @return the number of entity expansions
     * permitted in a document
     */
    public int getEntityExpansionLimit() {
        return entityExpansionLimit;
    }

    /**
     * <p>Sets the limit of the number of content model nodes
     * that may be created when building a grammar for a W3C
     * XML Schema that contains maxOccurs attributes with values
     * other than "unbounded".</p>
     *
     * @param limit the maximum value for maxOccurs other
     * than "unbounded"
     */
    public void setMaxOccurNodeLimit(int limit){
        maxOccurLimit = limit;
    }

    /**
     * <p>Returns the limit of the number of content model nodes
     * that may be created when building a grammar for a W3C
     * XML Schema that contains maxOccurs attributes with values
     * other than "unbounded".</p>
     *
     * @return the maximum value for maxOccurs other
     * than "unbounded"
     */
    public int getMaxOccurNodeLimit(){
        return maxOccurLimit;
    }

    public int getElementAttrLimit(){
                return fElementAttributeLimit;
        }

        public void setElementAttrLimit(int limit){
                fElementAttributeLimit = limit;
        }

        private void readSystemProperties(){

                try {
                        String value = System.getProperty(Constants.ENTITY_EXPANSION_LIMIT);
                        if(value != null && !value.equals("")){
                                entityExpansionLimit = Integer.parseInt(value);
                                if (entityExpansionLimit < 0)
                                        entityExpansionLimit = DEFAULT_ENTITY_EXPANSION_LIMIT;
                        }
                        else
                                entityExpansionLimit = DEFAULT_ENTITY_EXPANSION_LIMIT;
                }catch(Exception ex){}

                try {
                        String value = System.getProperty(Constants.MAX_OCCUR_LIMIT);
                        if(value != null && !value.equals("")){
                                maxOccurLimit = Integer.parseInt(value);
                                if (maxOccurLimit < 0)
                                        maxOccurLimit = DEFAULT_MAX_OCCUR_NODE_LIMIT;
                        }
                        else
                                maxOccurLimit = DEFAULT_MAX_OCCUR_NODE_LIMIT;
                }catch(Exception ex){}

                try {
                        String value = System.getProperty(Constants.ELEMENT_ATTRIBUTE_LIMIT);
                        if(value != null && !value.equals("")){
                                fElementAttributeLimit = Integer.parseInt(value);
                                if ( fElementAttributeLimit < 0)
                                        fElementAttributeLimit = DEFAULT_ELEMENT_ATTRIBUTE_LIMIT;
                        }
                        else
                                fElementAttributeLimit = DEFAULT_ELEMENT_ATTRIBUTE_LIMIT;

                }catch(Exception ex){}

        }

} // class SecurityManager