Click here to close now.

Welcome!

Cloud Security Authors: Pat Romanski, Dana Gardner, Elizabeth White, Liz McMillan, Harry Trott

Related Topics: Java IoT, Cloud Security

Java IoT: Article

How to Provide Dynamic Security Permissions

Two approaches

For various reasons, an application may install a security manager. Usually it does so to guard against malicious third-party code either installed or dynamically downloaded at runtime. If the application uses RMI APIs, it's even required by a Java specification that a security manager be installed, otherwise the classloader will not download any classes from remote locations.

The most convenient security manager to use is java.lang.SecurityManager. Once installed, it will work with security policy to control the security permissions granted to different protection domains. For simplicity, it will be referred to as SecurityManager for the rest of this article.

The security policy is statically initialized at application start-up. For Sun's JDK, the security policy is defined in a security policy file. Naturally, this initial security policy cannot be changed at runtime once it's loaded with the application.

What if you want the security permissions to change at runtime? For example, you have a list of hosts from which the socket connection requests should not be accepted by the security manager. This list keeps changing when the application is running and you don't want to shut the application down to make the latest list effective. Or you feel that the expressions allowed in the security policy file are not enough for your application. Sure, it allows wildcards like "*", but you need something more dynamic and powerful, like a regular expression. What can you do?

Before any solution is proposed, let's take a look at how security permissions are managed normally. First, create a security policy that defines a set of security permissions granted to one or more protection domains, then install java.lang.SecurityManager at the start of your application. When the application calls a security-sensitive API, the API first checks with the SecurityManager to determine whether certain operations are allowed. The SecurityManager calls AccessContoller.checkPermission() method, which in turn consults the security policy when making security permission decisions.

It's not difficult to find out from the above that three components work together to provide security permissions - a security manager, a security policy, and the AccessContoller. AccessController is a final class and cannot be dynamically set with the system, so there's nothing we can do about it. SecurityManager and Policy, on the other hand, are extendable and can be set with the system.

It seems there are two approaches - writing your own security manager or writing your own security policy.

Writing Your Own Security Manager
If you take a look at SecurityManager APIs, the bulk of them are two checkPermission() methods and some checkOperation() methods, where Operation is an action like Connect, Listen, SetFactory, etc. If the security permission is granted, these methods simply return without doing anything. Otherwise, they throw SecurityException to indicate that the related security permission is denied. To dynamically control the behavior, just override one or more such APIs. If a method is not overridden, leave the behavior to SecurityManager and essentially the security policy to decide.

So far this seems easy. Is that so? Let's find out with a simple example. In this example, you want to control which properties can be accessed by overriding the checkPropertyAccess(String key) API. It's assumed that the list of accessible properties keeps changing and you get a fresh list each time checkPropertyAccess(String key) is invoked (see Listing 1).

You don't expect to get a security exception because we allow access to "user.home". By the way, if you use a security policy file that grants PropertyPermission to access "user.home" and "user.dir" and install a SecurityManager, TestProperty prints out the value of "user.home" just as expected.

If you run TestProperty with MySecurityManager in Sun's JDK 1.4.2, it prints out the following:

Exception in thread "main" java.lang.ExceptionInInitializerError
at java.lang.System.setSecurityManager0(System.java:243)
at java.lang.System.setSecurityManager(System.java:212)
at TestProperty.main(TestProperty.java:5)
Caused by: java.lang.SecurityException: Not allowed!
at MySecurityManager.checkPropertyAccess(MySecurityManager.java:9)
at java.lang.System.getProperty(System.java:573)
at java.lang.Integer.getInteger(Integer.java:814)
at java.lang.Integer.getInteger(Integer.java:731)
at sun.security.action.GetIntegerAction.run(GetIntegerAction.java:90)
at java.security.AccessController.doPrivileged(Native Method)
at sun.net.InetAddressCachePolicy.<clinit>(InetAddressCachePolicy.java:94)
... 3 more

The exception is thrown from System.setSecurityManager() and is caused by a read of property "su.net.inetaddr.ttl", which is totally unrelated to our code. Seems like you just shot yourself in the foot, yet you don't know where the bullet came from.

Actually it's not important to know where the check comes from, but it is important to note that the security exception is caused by an AccessController.doPrivileged() call.

When we try the TestProperty application with the standard SecurityManager and security policy, AccessController.doPrivileged doesn't throw a security exception. This is because SecurityManager.checkPropertyAccess() delegates to checkPermission(), which in turn calls AccessController.checkPermission(). AccessController knows how to handle privileged code blocks. When it sees a privileged code block and the associated protection domain has the required permission, it returns without further checking callers of the privileged code block on the call stack. In our case, the privileged code block is in the sun.net.InetAddressCachePolicy, which is from the system domain that has all the permissions.

Let's go back to MySecurityManager. There is no way for it to know whether a call is from a privileged code block or the information about the call stack. It grants and denies the same set of permissions to all protection domains, even if the protection domain is the system domain where all permissions should be granted. That's where the problem comes from.

For more details regarding AccessController, I encourage you to check out the JavaDoc for the AccessController and security documentation at http://java.sun.com/j2se/1.4.2/docs/guide/security/ spec/security-spec.doc4.html#20389.

It's important to note that MySecurityManager tends to be more restrictive than SecurityManager (or the initial security policy) by specifically disallowing access to most of the properties. On the other hand, an application may need a security manager that is less restrictive than the initial security policy at certain times. In this case, override a SecurityManager's check method in the following manner:

  1. Specifically allow an action by directly returning from the method when a condition is met.
  2. Otherwise delegate to the same checkOperation() method in its super class to get the default behavior controlled by the initial security policy.

More Stories By Xiaozhong Wang

Xiaozhong Wang is a software engineer at Sun where he has solved some security problems in his TCK (Technology Compatibility Kit) work.

Comments (0)

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


@ThingsExpo Stories
With major technology companies and startups seriously embracing IoT strategies, now is the perfect time to attend @ThingsExpo in Silicon Valley. Learn what is going on, contribute to the discussions, and ensure that your enterprise is as "IoT-Ready" as it can be! Internet of @ThingsExpo, taking place Nov 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 17th Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The Internet of Things (IoT) is the most profound change in personal an...
"We have a tagline - "Power in the API Economy." What that means is everything that is built in applications and connected applications is done through APIs," explained Roberto Medrano, Executive Vice President at Akana, in this SYS-CON.tv interview at 16th Cloud Expo, held June 9-11, 2015, at the Javits Center in New York City.
To many people, IoT is a buzzword whose value is not understood. Many people think IoT is all about wearables and home automation. In his session at @ThingsExpo, Mike Kavis, Vice President & Principal Cloud Architect at Cloud Technology Partners, discussed some incredible game-changing use cases and how they are transforming industries like agriculture, manufacturing, health care, and smart cities. He will discuss cool technologies like smart dust, robotics, smart labels, and much more. Prepare to be blown away with a glimpse of the future.
WebRTC converts the entire network into a ubiquitous communications cloud thereby connecting anytime, anywhere through any point. In his session at WebRTC Summit,, Mark Castleman, EIR at Bell Labs and Head of Future X Labs, will discuss how the transformational nature of communications is achieved through the democratizing force of WebRTC. WebRTC is doing for voice what HTML did for web content.
The 17th International Cloud Expo has announced that its Call for Papers is open. 17th International Cloud Expo, to be held November 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA, brings together Cloud Computing, APM, APIs, Microservices, Security, Big Data, Internet of Things, DevOps and WebRTC to one location. With cloud computing driving a higher percentage of enterprise IT budgets every year, it becomes increasingly important to plant your flag in this fast-expanding business opportunity. Submit your speaking proposal today!
The 5th International DevOps Summit, co-located with 17th International Cloud Expo – being held November 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA – announces that its Call for Papers is open. Born out of proven success in agile development, cloud computing, and process automation, DevOps is a macro trend you cannot afford to miss. From showcase success stories from early adopters and web-scale businesses, DevOps is expanding to organizations of all sizes, including the world's largest enterprises – and delivering real results. Among the proven benefits, DevOps is corr...
17th Cloud Expo, taking place Nov 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA, will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud strategy. Meanwhile, 94% of enterprises are using some form of XaaS – software, platform, and infrastructure as a service.
The 4th International Internet of @ThingsExpo, co-located with the 17th International Cloud Expo - to be held November 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA - announces that its Call for Papers is open. The Internet of Things (IoT) is the biggest idea since the creation of the Worldwide Web more than
Explosive growth in connected devices. Enormous amounts of data for collection and analysis. Critical use of data for split-second decision making and actionable information. All three are factors in making the Internet of Things a reality. Yet, any one factor would have an IT organization pondering its infrastructure strategy. How should your organization enhance its IT framework to enable an Internet of Things implementation? In his session at @ThingsExpo, James Kirkland, Red Hat's Chief Architect for the Internet of Things and Intelligent Systems, described how to revolutionize your archit...
SYS-CON Events announced today that Secure Infrastructure & Services will exhibit at SYS-CON's 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. Secure Infrastructure & Services (SIAS) is a managed services provider of cloud computing solutions for the IBM Power Systems market. The company helps mid-market firms built on IBM hardware platforms to deploy new levels of reliable and cost-effective computing and high availability solutions, leveraging the cloud and the benefits of Infrastructure-as-a-Service (IaaS...
SYS-CON Events announced today that ProfitBricks, the provider of painless cloud infrastructure, will exhibit at SYS-CON's 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. ProfitBricks is the IaaS provider that offers a painless cloud experience for all IT users, with no learning curve. ProfitBricks boasts flexible cloud servers and networking, an integrated Data Center Designer tool for visual control over the cloud and the best price/performance value available. ProfitBricks was named one of the coolest Clo...
Internet of Things is moving from being a hype to a reality. Experts estimate that internet connected cars will grow to 152 million, while over 100 million internet connected wireless light bulbs and lamps will be operational by 2020. These and many other intriguing statistics highlight the importance of Internet powered devices and how market penetration is going to multiply many times over in the next few years.
The basic integration architecture, as defined by ESBs, hasn’t changed for more than a decade. Most cloud integration providers still rely on an ESB architecture and their proprietary connectors. As a result, enterprise integration projects suffer from constraints of availability and reliability of these connectors that are not re-usable across other integration vendors. However, the rapid adoption of APIs and almost ubiquitous availability of APIs amongst most SaaS and Cloud applications are rapidly redefining traditional integration approaches and their reliance on proprietary connectors. ...
SYS-CON Events announced today that Dyn, the worldwide leader in Internet Performance, will exhibit at SYS-CON's 17th International Cloud Expo®, which will take place on November 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. Dyn is a cloud-based Internet Performance company. Dyn helps companies monitor, control, and optimize online infrastructure for an exceptional end-user experience. Through a world-class network and unrivaled, objective intelligence into Internet conditions, Dyn ensures traffic gets delivered faster, safer, and more reliably than ever.
Today air travel is a minefield of delays, hassles and customer disappointment. Airlines struggle to revitalize the experience. GE and M2Mi will demonstrate practical examples of how IoT solutions are helping airlines bring back personalization, reduce trip time and improve reliability. In their session at @ThingsExpo, Shyam Varan Nath, Principal Architect with GE, and Dr. Sarah Cooper, M2Mi’s VP Business Development and Engineering, will explore the IoT cloud-based platform technologies driving this change including privacy controls, data transparency and integration of real time context wi...
Buzzword alert: Microservices and IoT at a DevOps conference? What could possibly go wrong? In this Power Panel at DevOps Summit, moderated by Jason Bloomberg, the leading expert on architecting agility for the enterprise and president of Intellyx, panelists peeled away the buzz and discuss the important architectural principles behind implementing IoT solutions for the enterprise. As remote IoT devices and sensors become increasingly intelligent, they become part of our distributed cloud environment, and we must architect and code accordingly. At the very least, you'll have no problem fillin...
The Internet of Things is not only adding billions of sensors and billions of terabytes to the Internet. It is also forcing a fundamental change in the way we envision Information Technology. For the first time, more data is being created by devices at the edge of the Internet rather than from centralized systems. What does this mean for today's IT professional? In this Power Panel at @ThingsExpo, moderated by Conference Chair Roger Strukhoff, panelists addressed this very serious issue of profound change in the industry.
Internet of Things (IoT) will be a hybrid ecosystem of diverse devices and sensors collaborating with operational and enterprise systems to create the next big application. In their session at @ThingsExpo, Bramh Gupta, founder and CEO of robomq.io, and Fred Yatzeck, principal architect leading product development at robomq.io, discussed how choosing the right middleware and integration strategy from the get-go will enable IoT solution developers to adapt and grow with the industry, while at the same time reduce Time to Market (TTM) by using plug and play capabilities offered by a robust IoT ...
It is one thing to build single industrial IoT applications, but what will it take to build the Smart Cities and truly society-changing applications of the future? The technology won’t be the problem, it will be the number of parties that need to work together and be aligned in their motivation to succeed. In his session at @ThingsExpo, Jason Mondanaro, Director, Product Management at Metanga, discussed how you can plan to cooperate, partner, and form lasting all-star teams to change the world and it starts with business models and monetization strategies.
SYS-CON Events announced today that BMC will exhibit at SYS-CON's 16th International Cloud Expo®, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. BMC delivers software solutions that help IT transform digital enterprises for the ultimate competitive business advantage. BMC has worked with thousands of leading companies to create and deliver powerful IT management services. From mainframe to cloud to mobile, BMC pairs high-speed digital innovation with robust IT industrialization – allowing customers to provide amazing user experiences with optimized IT per...