Home > Articles > Programming > Java

Advanced JavaServer Pages Security

Many books have been written about the wide ranging topic of computer security, including Java security. In this sample chapter, author David Geary discusses protecting web application resources with the authentication mechanisms described in the servlet specification.
This sample chapter is excerpted from Advanced JavaServer Pages, by David Geary.
This chapter is from the book

This chapter is from the book

Topics in this Chapter

  • Servlet Authentication
  • Principals and Roles
  • Declarative Authentication
  • Portability
  • Types of Authentication
  • Basic Authentication
  • Digest Authentication
  • Form-Based Authentication
  • SSL and Client Certificate Authentication
  • Web Application Security Elements
  • Customizing Authentication
  • Resin
  • Tomcat 4.0
  • Programmatic Authentication

Computer security used to be the domain of hackers and their antagonists, but with the advent of the World Wide Web, it's become an issue for the rank and file setting up shop on the net. Because of this growing awareness, software developers today are far more likely to deal with security than were their counterparts of the late 20th century.

Many books have been written about the wide ranging topic of computer security, including Java security, and this chapter is a substitute for none of them. This discussion is restricted to protecting web application resources with the authentication mechanisms described in the servlet specification.1

Servlet Authentication

Servlet authentication looks simple:

  1. A user tries to access a protected resource, such as a JSP page.

  2. If the user has been authenticated, the servlet container makes the resource available; otherwise, the user is asked for a username and password.

  3. If the name and password cannot be authenticated, an error is displayed and the user is given the opportunity to enter a new username and password.

The steps outlined above are simple, but vague. It's not apparent who asks for a username and password, who does the authentication, how it's performed, or even how the user is asked for a username and password. Those steps are unspecified because the servlet specification leaves them up to applications and servlet containers. This vagueness in the servlet specification has an effect on portability; see "Portability" for more information.

Principals and Roles

In security-speak, the user in the steps listed on page 251 is a principal. Principals are named entities that can represent anything; most often, they represent individuals or corporations.

Principals can fill one or more roles; for example, a customer could also be an employee. Security constraints in WEB-INF/web.xml associate roles with protected resources, like this:

 <web-app>
 ...
  <security-constraint>
    <!-- web resources that are protected -->
    <web-resource-collection>
     <web-resource-name>Protected Resource</web-resource-name>
     <url-pattern>/page_1.jsp</url-pattern>
    </web-resource-collection>
 
    <auth-constraint>
     <!-- role-name indicates roles that are allowed
        to access the web resources specified above -->
     <role-name>customer</role-name>
    </auth-constraint>
  </security-constraint>
 ...
  <security-constraint>
    <!-- web resources that are protected -->
    <web-resource-collection>
     <web-resource-name>Protected Resource2</web-resource-name>
     <url-pattern>/page_2.jsp</url-pattern>
    </web-resource-collection>
 
    <auth-constraint>
     <!-- role-name indicates roles that are allowed
        to access the web resources specified above -->
     <role-name>employee</role-name>
    </auth-constraint>
  </security-constraint>
 <web-app>

Two security constraints are specified above that restrict access to /page_1.jsp and /page_2.jsp to principals that are in roles customer or employee, respectively.

Security constraints, like those listed above, associate resources with roles. It's up to servlet containers or applications to associate roles with principals; for example, with Tomcat, you edit a tomcat-users.xml file that has entries like this:

 <tomcat-users>
  ...
  <user name="rwhite" password="tomcat" roles="customer", "other"/>
  ...
 </tomcat-users>

Here, rwhite has a password of tomcat and can fill roles customer or other; thus, rwhite can access /page_1.jsp, but not /page_2.jsp according to the security constraints listed above.

Other servlet containers provide different mechanisms for associating principals with roles; for example, "Resin" illustrates how it's done with Resin for basic authentication.

Table 9-1 lists HttpServletRequest methods that allow you to retrieve information about principals and roles.

Table 9-1 HttpServletRequest Methods for Principals and Roles

Method

Description

Principal getUserPrincipal()

Returns a reference to a java.security.Principal

boolean isUserInRole(String)

Determines whether a user is in a role, specified by the string argument

String getRemoteUser()

Returns the username that was used for login


The servlet API does not provide corresponding setter methods for the getter methods listed in Table 9-1; therefore, principals and roles can only be set by servlet containers, meaning that applications cannot set them. This can be a consideration if you implement programmatic authentication–see "Programmatic Authentication" for more information.

Table 9-2 lists other ServletRequest methods that provide security information.

Table 9-2 Other ServletRequest Security Methods1

Method

Description

String getAuthType()

Returns the authentication type: BASIC, SSL, or null

boolean isSecure()

Returns true if the connection is HTTPS

String getScheme()

Scheme represents transport mechanism: http, https...


Like the methods listed in Table 9-1, the servlet API does not provide corresponding setter methods for those methods listed in Table 9-2. This means that the authentication type and transport scheme can only be set by servlet containers.

Declarative Authentication

Declarative authentication requires no programming because authentication is declared with XML tags in a deployment descriptor and implemented by the servlet container. Declarative authentication is attractive because it's easy, but it's not as flexible as other approaches that require you to write code.

At one end of the spectrum is, declarative authentication, with is 100% servlet container implemented and 0% application code; at the other end is programmatic authentication, with 0% servlet container and 100% application code.

Most servlet containers provide access to the middle of that spectrum by providing hooks so that you can replace their default authentication mechanism.

"Basic Authentication" provides an example of declarative authentication, "Customizing Authentication" illustrates customizing authentication, and programmatic authentication is discussed in "Programmatic Authentication".

Portability

The servlet specification leaves enough security details unspecified that servlet containers must fill in the gaps with nonportable functionality. For example, the servlet specification does not specify a default authentication mechanism, so servlet containers implement their own; for example, Tomcat uses an XML file to specify usernames and passwords, whereas Resin requires you to implement an authenticator.

Because of nonportable security aspects of servlet containers and depending upon your choice for authentication, you may need to write some nonportable code, such as a Resin authenticator or a Tomcat realm, both of which are discussed in "Customizing Authentication".

On the other hand, you can use declarative authentication to minimize any code you have to write.

Types of Authentication

A servlet-based web application can choose from the following types of authentication, from least secure to most:

  • Basic authentication
  • Form-based authentication
  • Digest authentication
  • SSL and client certificate authentication

All of the authentication mechanisms listed above are discussed in this chapter. Basic and digest authentication are discussed in much detail in RFC2617, which can be found at ftp://ftp.isi.edu/in-notes/rfc2617.txt.

You select one of the authentication mechanisms listed above in /WEBINF/web.xml, like this:

 <web-app>
 ...
  <login-config>
    <auth-method>BASIC</auth-method>
    <realm-name>Basic Authentication Example</realm-name>
  </login-config>
 ...
 </web-app>

Although basic and form-based authentication are not secure, you can use them in combination with SSL for secure transport.

You can find out the authentication method for a request with HttpServletRequest.getAuthType–see Table 9-2.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020