Home > Articles > Programming > Windows Programming

  • Print
  • + Share This

Operation Based Security

In custom developed applications, role based security provides a sufficient degree of flexibility. However, when the same application is running on different customers' sites, some issues are likely to arise. Suppose that you have a financial application. In this application, a class is responsible for triggering the payment procedure of financial deals. Using role based security you have defined a role hierarchy and placed a security demand for BackOffice or Administrators roles on the class that runs the payment procedure. Given this structure, a customer tells you that, in his company, people in the role of FrontOffice can run the payment procedure as well. Unfortunately, adding the FrontOffice employees in the BackOffice role as well is not an option because you would give them access to all the sensitive operations assigned by your application to the BackOffice role.

At this point, you are stuck in the sense that you need to develop a customization for that customer; that is, you need to recompile the previously mentioned class in order to have it require BackOffice or FrontOffice membership.

The solution to this problem is to ask for permission on specific operations in the application code instead of role membership. The definition of which roles can execute a specific operation is pulled out from the compiled code and placed into another configuration file. In the proposed implementation of operation based security, this file will look like the following:

<root>
 <operation name="sensitiveoperation">
 <role name="ApplicationAdmins" />
 </operation>
 <operation name="openform">
 <params>
  <param name="formname" value="reports" />
  <param name="edit" value="true" />
  <role name="ApplicationAdmins" />
 </params>
 <params>
  <param name="formname" value="reports" />
  <param name="edit" value="false" />
  <role name="ApplicationUsers"> />
  <role name="ApplicationAdmins" />
 </params>
 </operation>
<operation name="noadmins">
 <params>
 <param name="formname" value="anotherform" />
 <role name="ApplicationUsers" />
 </params>
</operation>
</root>

An explanation is in order for the param attributes. In a real world application, it's quite difficult when all access checks can be expressed declaratively against a single operation-name string value (as shown in the first operation section of the sample XML file). For instance, consider how to express the permissions for opening a form in read-only mode for all users and read-write mode for power users.

What you need is the opportunity to specify some additional parameters on each operation name. The number and meaning of name value pairs are unconstrained. The authorization module will accept any number of them from the calling application and will try to match them on the operation configuration file constructing the proper XPath query, totally oblivious of their application meaning. That said, it should be quite clear why role assignment in the configuration XML file isn't done at operation level, but at the parameters set level instead.

The complexity and the number of parameters required on average for an operation check may vary greatly, and it depends a lot on the encapsulation and the good design of the application in which you are applying authorization checks. A brittle application architecture will lead to a brittle structure of operations (and their parameters).

The Authorization module based on operations checks extends the one shown in the previous paragraph (you can find both of them with the downloadable package that comes with this article).

Now the MycustomPrincipal class implements a new interface named IOperationCheck, which exposes a single method named IsOperationAllowed.

public interface IOperationCheck {
 bool IsOperationAllowed(string operation, params string[] p_params);
}

As you can see, this method accepts an operation name and an arbitrary number of parameters. Each one must be packed in the following form: "<paramname>=<paramvalue>". Following is a code snipped showing a client application calling the IsOperationAllowed method.

if(((IOperationCheck)Thread.CurrentPrincipal).IsOperationAllowed(
 "openform","formname=reports","edit=false")==true)
 //do work.. 
else
 throw new Exception ("Access Denied");

The implementation of the IsOperationAllowed is quite straightforward after you get the XPath query right. As you can see below, the construction of the XPath query for role membership and parameter matching has been factored into two separate private functions that are omitted for brevity (you can find the full code source here).

public bool IsOperationAllowed(string operation, params string[] p_params) {
 lock (i_xmloperations) {
 XmlNodeList l_nodelist = i_xmloperations.SelectNodes(
"/root/operation[@name='" + operation + "'" + pf_buildRoleClause(p_params)
   + pf_buildParamClause(p_params) + "]");
 return l_nodelist.Count > 0 ? true: false;
 }
}

As a possible refinement, you could extend the params syntax to evaluate against inequality as well:

<operation name="noadmins">
 <params>
 <!-- calling code must provide a value greater than 1000 for the income parameter -->
 <param name="income" value="1000" operator=">" />
 <role name="ApplicationUsers"></role>
 </params>
</operation>

No matter how you extend the XML grammar, even a really well-designed application might require authorization logic at some point that can't be expressed in the form of name-value pair matching. (For instance, how can you declaratively implement access checks such as "Application users can do this if A is greater than 100 or B is less than 1000 or it's from 4 pm to 6 pm"?)

The solution in this case is to define some mechanisms and the proper grammar in the XML file to hook dynamically bites of scripting-based authorization logic. Unfortunately, this is out of the current article scope, so it's left as an exercise for the reader <g>.

However, if you want to follow this path, here's some advice:

  • Try to see if refactoring at method or class level can eliminate the need for code-based access checks.

  • Do not mix unwary access control and business logic together (specifically, avoid treating business logic as access control) because this can brittle your application architecture.

  • + Share This
  • 🔖 Save To Your Account

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