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          The Apache Jakarta Tomcat 5.5 Servlet/JSP Container

          Security Manager HOW-TO

          背景

          Java的SecurityManager允許瀏覽器在它可執(zhí)行的范圍內(nèi)運(yùn)行,這樣可以防止不可靠的程序讀寫(xiě)用戶(hù)在局部文件系統(tǒng)里的文件,或者未經(jīng)授權(quán)進(jìn)行網(wǎng)絡(luò)連接,等等。同樣,SecurityManager可用來(lái)防止不可靠的程序在你的瀏覽器上運(yùn)行,在運(yùn)行Tomcat時(shí)使用SecurityManager可以保護(hù)你的服務(wù)器不受到類(lèi)似于木馬的servlets, JSPs, JSP beans 和 tag libraries的影響,或者發(fā)生錯(cuò)誤。

          試想某個(gè)被允許在你的網(wǎng)站上發(fā)表JSPs的人不慎包括了以下的語(yǔ)句在他們的JSP里:

          <%System.exit(1);%>

          每次Tomcat運(yùn)行該JSP都會(huì)導(dǎo)致Tomcat中斷。使用Java SecurityManager如同多了一層防護(hù),可以讓服務(wù)器更加安全可靠。

          警告——雖然Tomcat 5的程序通過(guò)了安全檢查,最重要的程序包都已被保護(hù),新的安全機(jī)制也已實(shí)施,但在允許用戶(hù)發(fā)表網(wǎng)絡(luò)程序,JSPs, servlets, beans, 或 tag libraries之前,你還是有必要確保SecurityManager的各項(xiàng)配置符合你的要求。當(dāng)然,有SecurityManager絕對(duì)比沒(méi)有它要安全的多。

          許可權(quán)限

          Permission類(lèi)是用來(lái)定義Tomcat載入的類(lèi)所擁有的權(quán)限。Java本身包括了一些Permission類(lèi),你也可以在你的網(wǎng)絡(luò)應(yīng)用中加入你自己的Permission類(lèi)。這兩種技術(shù)在Tomcat 5里都被應(yīng)用。

          標(biāo)準(zhǔn)許可權(quán)限

          這里簡(jiǎn)單總結(jié)了標(biāo)準(zhǔn)系統(tǒng)中適用于Tomcat的SecurityManager Permission 類(lèi)。更多信息請(qǐng)參看http://java.sun.com/security/

          • java.util.PropertyPermission - 控制讀/寫(xiě)Java虛擬器的屬性,如java.home
          • java.lang.RuntimePermission - 控制使用一些系統(tǒng)/運(yùn)行時(shí)(System/Runtime)的功能,如exit()exec()。它也控制包(package)的訪(fǎng)問(wèn)/定義。
          • java.io.FilePermission - 控制對(duì)文件和目錄的讀/寫(xiě)/執(zhí)行操作。
          • java.net.SocketPermission - 控制使用網(wǎng)路sockets連接。
          • java.net.NetPermission - 控制使用multicast網(wǎng)路連接。
          • java.lang.reflect.ReflectPermission - 控制使用reflection來(lái)對(duì)類(lèi)進(jìn)行檢視。
          • java.security.SecurityPermission - 控制對(duì)安全方法的訪(fǎng)問(wèn)。
          • java.security.AllPermission - 給予所有訪(fǎng)問(wèn)權(quán)限,就如你運(yùn)行一個(gè)沒(méi)有SecurityManager的Tomcat 。
          Tomcat用戶(hù)特有權(quán)限

          Tomcat利用一個(gè)叫做org.apache.naming.JndiPermission 客戶(hù)許可類(lèi)。它用來(lái)控制以JNDI命名的文件資源的可讀權(quán)限。該許可的名稱(chēng)是以JNDI來(lái)表達(dá),沒(méi)有命令。在給予許可時(shí),"*"的結(jié)尾可以用來(lái)以wild card方式映射JNDI命名的文件資源。例如,你可以在你的政策(policy)文件加入以下一行:

          permission org.apache.naming.JndiPermission "jndi://localhost/examples/*";

          一個(gè)象這樣的許可(Permission)會(huì)在部署網(wǎng)絡(luò)程序時(shí)被自動(dòng)產(chǎn)生,允許它讀取它自己的靜態(tài)資源,但不允許它使用文件訪(fǎng)問(wèn)權(quán)來(lái)讀取其它文件(除非你明確地給出訪(fǎng)問(wèn)那些文件的許可).

          并且, Tomcat 總是自動(dòng)產(chǎn)生以下文件許可:

          permission java.io.FilePermission "** your application context**", "read";

          這里**your application context**代表那個(gè)擁有你的應(yīng)用程序的文件夾(或者是WAR文件)。

          用SecurityManager配置Tomcat

          政策文件的格式

          由Java SecurityManager實(shí)現(xiàn)的安全政策被配置存放在$CATALINA_HOME/conf/catalina.policy 文件里。這個(gè)文件完全替代了JDK系統(tǒng)目錄里的java.policy文件。這個(gè)catalina.policy 文件可以手動(dòng)修改,或者使用Java 1.2 及其后版本的policytool程序修改。 ?$CATALINA_HOME/conf/catalina.policy

          catalina.policy 文件中的條文使用了標(biāo)準(zhǔn)的java.policy文件格式,如下:

          // Example policy file entry 
          
          grant [signedBy <signer>,] [codeBase <code source>] { 
          permission <class> [<name> [, <action list>]]; 
          };

          其中signedBycodeBase是選擇項(xiàng)。注釋行是以"http://"開(kāi)始,直到該行結(jié)束。codeBase是URL的格式,文件的URL中可用如${java.home}和${catalina.home}等屬性(這些屬性會(huì)被擴(kuò)展到由環(huán)境變量JAVA_HOMECATALINA_HOME為他們定義的目錄路徑)。 ?${catalina.home}

          缺省政策文件

          缺省$CATALINA_HOME/conf/catalina.policy 文件看起來(lái)象這樣: ?$CATALINA_HOME/conf/catalina.policy

          // ============================================================================
          // catalina.corepolicy - Security Policy Permissions for Tomcat 5
          //
          // This file contains a default set of security policies to be enforced (by the
          // JVM) when Catalina is executed with the "-security" option.  In addition
          // to the permissions granted here, the following additional permissions are
          // granted to the codebase specific to each web application:
          //
          // * Read access to the document root directory
          //
          // $Id: security-manager-howto.xml,v 1.5 2003/01/15 03:40:43 glenn Exp $
          // ============================================================================
          
          
          // ========== SYSTEM CODE PERMISSIONS =========================================
          
          
          // These permissions apply to javac
          grant codeBase "file:${java.home}/lib/-" {
                  permission java.security.AllPermission;
          };
          
          // These permissions apply to all shared system extensions
          grant codeBase "file:${java.home}/jre/lib/ext/-" {
                  permission java.security.AllPermission;
          };
          
          // These permissions apply to javac when ${java.home] points at $JAVA_HOME/jre
          grant codeBase "file:${java.home}/../lib/-" {
                  permission java.security.AllPermission;
          };
          
          // These permissions apply to all shared system extensions when
          // ${java.home} points at $JAVA_HOME/jre
          grant codeBase "file:${java.home}/lib/ext/-" {
                  permission java.security.AllPermission;
          };
          
          
          // ========== CATALINA CODE PERMISSIONS =======================================
          
          
          // These permissions apply to the launcher code
          grant codeBase "file:${catalina.home}/bin/commons-launcher.jar" {
                  permission java.security.AllPermission;
          };
          
          // These permissions apply to the server startup code
          grant codeBase "file:${catalina.home}/bin/bootstrap.jar" {
                  permission java.security.AllPermission;
          };
          
          // These permissions apply to the servlet API classes
          // and those that are shared across all class loaders
          // located in the "common" directory
          grant codeBase "file:${catalina.home}/common/-" {
                  permission java.security.AllPermission;
          };
          
          // These permissions apply to the container's core code, plus any additional
          // libraries installed in the "server" directory
          grant codeBase "file:${catalina.home}/server/-" {
                  permission java.security.AllPermission;
          };
          
          // ========== WEB APPLICATION PERMISSIONS =====================================
          
          
          // These permissions are granted by default to all web applications
          // In addition, a web application will be given a read FilePermission
          // and JndiPermission for all files and directories in its document root.
          grant { 
                  // Required for JNDI lookup of named JDBC DataSource's and
                  // javamail named MimePart DataSource used to send mail
                  permission java.util.PropertyPermission "java.home", "read";
                  permission java.util.PropertyPermission "java.naming.*", "read";
                  permission java.util.PropertyPermission "javax.sql.*", "read";
          
                  // OS Specific properties to allow read access
          	permission java.util.PropertyPermission "os.name", "read";
          	permission java.util.PropertyPermission "os.version", "read";
          	permission java.util.PropertyPermission "os.arch", "read";
          	permission java.util.PropertyPermission "file.separator", "read";
          	permission java.util.PropertyPermission "path.separator", "read";
          	permission java.util.PropertyPermission "line.separator", "read";
          
                  // JVM properties to allow read access
                  permission java.util.PropertyPermission "java.version", "read";
                  permission java.util.PropertyPermission "java.vendor", "read";
                  permission java.util.PropertyPermission "java.vendor.url", "read";
                  permission java.util.PropertyPermission "java.class.version", "read";
          	permission java.util.PropertyPermission "java.specification.version", "read";
          	permission java.util.PropertyPermission "java.specification.vendor", "read";
          	permission java.util.PropertyPermission "java.specification.name", "read";
          
          	permission java.util.PropertyPermission "java.vm.specification.version", "read";
          	permission java.util.PropertyPermission "java.vm.specification.vendor", "read";
          	permission java.util.PropertyPermission "java.vm.specification.name", "read";
          	permission java.util.PropertyPermission "java.vm.version", "read";
          	permission java.util.PropertyPermission "java.vm.vendor", "read";
          	permission java.util.PropertyPermission "java.vm.name", "read";
          
                  // Required for getting BeanInfo
                  permission java.lang.RuntimePermission "accessClassInPackage.sun.beans.*";
          
                  // Required for OpenJMX
                  permission java.lang.RuntimePermission "getAttribute";
          
          	// Allow read of JAXP compliant XML parser debug
          	permission java.util.PropertyPermission "jaxp.debug", "read";
          };
          
          
          // You can assign additional permissions to particular web applications by
          // adding additional "grant" entries here, based on the code base for that
          // application, /WEB-INF/classes/, or /WEB-INF/lib/ jar files.
          //
          // Different permissions can be granted to JSP pages, classes loaded from
          // the /WEB-INF/classes/ directory, all jar files in the /WEB-INF/lib/
          // directory, or even to individual jar files in the /WEB-INF/lib/ directory.
          //
          // For instance, assume that the standard "examples" application
          // included a JDBC driver that needed to establish a network connection to the
          // corresponding database and used the scrape taglib to get the weather from
          // the NOAA web server.  You might create a "grant" entries like this:
          //
          // The permissions granted to the context root directory apply to JSP pages.
          // grant codeBase "file:${catalina.home}/webapps/examples/-" {
          //      permission java.net.SocketPermission "dbhost.mycompany.com:5432", "connect";
          //      permission java.net.SocketPermission "*.noaa.gov:80", "connect";
          // };
          //
          // The permissions granted to the context WEB-INF/classes directory
          // grant codeBase "file:${catalina.home}/webapps/examples/WEB-INF/classes/-" {
          // };
          //
          // The permission granted to your JDBC driver
          // grant codeBase "jar:file:${catalina.home}/webapps/examples/WEB-INF/lib/driver.jar!/-" {
          //      permission java.net.SocketPermission "dbhost.mycompany.com:5432", "connect";
          // };
          // The permission granted to the scrape taglib
          // grant codeBase "jar:file:${catalina.home}/webapps/examples/WEB-INF/lib/scrape.jar!/-" {
          //      permission java.net.SocketPermission "*.noaa.gov:80", "connect";
          // };

          啟動(dòng)附帶SecurityManager的Tomcat

          在你配置好與SecurityManager一起使用的catalina.policy文件之后,你可以使用"-security"選項(xiàng)來(lái)啟動(dòng)Tomcat。

          $CATALINA_HOME/bin/catalina.sh start -security (Unix) 
          %CATALINA_HOME%\bin\catalina start -security (Windows)
          Tomcat里受保護(hù)包的配置

          從Tomcat 5開(kāi)始,現(xiàn)在可以配置Tomcat內(nèi)部包的許可。更多信息請(qǐng)參看 http://java.sun.com/security/seccodeguide.html

          警告:刪除缺省的包保護(hù),可能打開(kāi)一個(gè)安全漏洞。

          缺省的屬性文件

          缺省的$CATALINA_HOME/conf/catalina.properties 文件看起來(lái)象這樣: ?$CATALINA_HOME/conf/catalina.properties

          #
          # List of comma-separated packages that start with or equal this string
          # will cause a security exception to be thrown when
          # passed to checkPackageAccess unless the
          # corresponding RuntimePermission ("accessClassInPackage."+package) has
          # been granted.
          package.access=sun.,org.apache.catalina.,org.apache.coyote.,org.apache.tomcat.,
          org.apache.jasper.
          #
          # List of comma-separated packages that start with or equal this string
          # will cause a security exception to be thrown when
          # passed to checkPackageDefinition unless the
          # corresponding RuntimePermission ("defineClassInPackage."+package) has
          # been granted.
          #
          # by default, no packages are restricted for definition, and none of
          # the class loaders supplied with the JDK call checkPackageDefinition.
          #
          package.definition=sun.,java.,org.apache.catalina.,org.apache.coyote.,
          org.apache.tomcat.,org.apache.jasper.

          當(dāng)你完成配置SecurityManager所需的catalina.properties 文件,記住要重新啟動(dòng)Tomcat。

          排除故障

          如果你的網(wǎng)絡(luò)應(yīng)用程序試圖執(zhí)行沒(méi)有許可而被阻止的操作,SecurityManager探查出這樣的違規(guī)后,就會(huì)拋出一個(gè)AccessControLExceptionSecurityException 。 要查出究竟缺少哪個(gè)許可往往非常困難,一個(gè)方法是打印執(zhí)行過(guò)程中的所有關(guān)于安全決定的排錯(cuò)信息。這可以在啟動(dòng)Tomcat之前通過(guò)設(shè)置系統(tǒng)屬性來(lái)實(shí)現(xiàn)。最簡(jiǎn)單的辦法是修改CATALINA_OPTS 環(huán)境變量。在啟動(dòng)Tomcat之前,執(zhí)行下面這個(gè)命令:

          export CATALINA_OPTS=-Djava.security.debug=all (Unix) 
          set CATALINA_OPTS=-Djava.security.debug=all (Windows)

          (在啟動(dòng)Tomcat之前)。

          警告——這會(huì)產(chǎn)生很多megabytes的輸出。不過(guò),通過(guò)查找"FAILED"這個(gè)詞可以幫助你搜索問(wèn)題所在,并確定哪個(gè)許可是要找的問(wèn)題。請(qǐng)參看Java安全文檔資料,那里有你可指定的更多選項(xiàng)。

          posted on 2006-05-29 14:49 放水老倌 閱讀(904) 評(píng)論(0)  編輯  收藏 所屬分類(lèi): J2EE
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