Click here to close now.

Welcome!

Security Authors: Elizabeth White, Pat Romanski, Liz McMillan, Adrian Bridgwater, Jacob Olcott

Related Topics: Java, Security

Java: 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
From telemedicine to smart cars, digital homes and industrial monitoring, the explosive growth of IoT has created exciting new business opportunities for real time calls and messaging. In his session at @ThingsExpo, Ivelin Ivanov, CEO and Co-Founder of Telestax, shared some of the new revenue sources that IoT created for Restcomm – the open source telephony platform from Telestax. Ivelin Ivanov is a technology entrepreneur who founded Mobicents, an Open Source VoIP Platform, to help create, deploy, and manage applications integrating voice, video and data. He is the co-founder of TeleStax, a...
SYS-CON Events announced today that Akana, formerly SOA Software, has been named “Bronze Sponsor” of SYS-CON's 16th International Cloud Expo® New York, which will take place June 9-11, 2015, at the Javits Center in New York City, NY. Akana’s comprehensive suite of API Management, API Security, Integrated SOA Governance, and Cloud Integration solutions helps businesses accelerate digital transformation by securely extending their reach across multiple channels – mobile, cloud and Internet of Things. Akana enables enterprises to share data as APIs, connect and integrate applications, drive part...
VoxImplant has announced full WebRTC support in the newest versions of its Android SDK and iOS SDK. The updated SDKs, which enable audio and video calls on mobile devices, are now compatible with the WebRTC standard to allow any mobile app to communicate with WebRTC-enabled browsers, including Google Chrome, Mozilla Firefox, Opera, and, when available, Microsoft Spartan. The WebRTC-updated SDKs represent VoxImplant's continued leadership in simplifying the development of real-time communications (RTC) services for app developers. VoxImplant (built by Zingaya, the real-time communication servi...
SYS-CON Events announced today that CommVault has been named “Bronze Sponsor” of 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, and the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. A singular vision – a belief in a better way to address current and future data management needs – guides CommVault in the development of Singular Information Management® solutions for high-performance data protection, universal availability and sim...
SYS-CON Events announced today that SafeLogic has been named “Bag Sponsor” of SYS-CON's 16th International Cloud Expo® New York, which will take place June 9-11, 2015, at the Javits Center in New York City, NY. SafeLogic provides security products for applications in mobile and server/appliance environments. SafeLogic’s flagship product CryptoComply is a FIPS 140-2 validated cryptographic engine designed to secure data on servers, workstations, appliances, mobile devices, and in the Cloud.
SYS-CON Events announced today that StorPool Storage 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. StorPool is distributed storage software that allows service providers, enterprises and other cloud builders to run data storage on standard x86 servers, instead of using expensive and inefficient storage arrays (SAN).
The IoT Bootcamp is coming to Cloud Expo | @ThingsExpo on June 9-10 at the Javits Center in New York. Instructor. Registration is now available at http://iotbootcamp.sys-con.com/ Instructor Janakiram MSV previously taught the famously successful Multi-Cloud Bootcamp at Cloud Expo | @ThingsExpo in November in Santa Clara. Now he is expanding the focus to Janakiram is the founder and CTO of Get Cloud Ready Consulting, a niche Cloud Migration and Cloud Operations firm that recently got acquired by Aditi Technologies. He is a Microsoft Regional Director for Hyderabad, India, and one of the f...
SYS-CON Events announced today that kintone has been named “Bronze Sponsor” of 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, and the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. kintone promotes cloud-based workgroup productivity, transparency and profitability with a seamless collaboration space, build your own business application (BYOA) platform, and workflow automation system.
SYS-CON Events announced today that Site24x7, the cloud infrastructure monitoring service, 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. Site24x7 is a cloud infrastructure monitoring service that helps monitor the uptime and performance of websites, online applications, servers, mobile websites and custom APIs. The monitoring is done from 50+ locations across the world and from various wireless carriers, thus providing a global perspective of the end-user experience. Site24x7 supports monitoring H...
SYS-CON Events announced today that Intelligent Systems Services 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. Established in 1994, Intelligent Systems Services Inc. is located near Washington, DC, with representatives and partners nationwide. ISS’s well-established track record is based on the continuous pursuit of excellence in designing, implementing and supporting nationwide clients’ mission-critical systems. ISS has completed many successful projects in Healthcare, Commercial, Manufacturing, ...
The best mobile applications are augmented by dedicated servers, the Internet and Cloud services. Mobile developers should focus on one thing: writing the next socially disruptive viral app. Thanks to the cloud, they can focus on the overall solution, not the underlying plumbing. From iOS to Android and Windows, developers can leverage cloud services to create a common cross-platform backend to persist user settings, app data, broadcast notifications, run jobs, etc. This session provides a high level technical overview of many cloud services available to mobile app developers, includi...
SYS-CON Events announced today that B2Cloud, a provider of enterprise resource planning software, 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. B2cloud develops the software you need. They have the ideal tools to help you work with your clients. B2Cloud’s main solutions include AGIS – ERP, CLOHC, AGIS – Invoice, and IZUM
WebRTC is an up-and-coming standard that enables real-time voice and video to be directly embedded into browsers making the browser a primary user interface for communications and collaboration. WebRTC runs in a number of browsers today and is currently supported in over a billion installed browsers globally, across a range of platform OS and devices. Today, organizations that choose to deploy WebRTC applications and use a host machine that supports audio through USB or Bluetooth can use Plantronics products to connect and transit or receive the audio associated with the WebRTC session.
The WebRTC Summit 2015 New York, to be held June 9-11, 2015, at the Javits Center in New York, NY, announces that its Call for Papers is open. Topics include all aspects of improving IT delivery by eliminating waste through automated business models leveraging cloud technologies. WebRTC Summit is co-located with 16th International Cloud Expo, @ThingsExpo, Big Data Expo, and DevOps Summit.
SYS-CON Events announced today that Tufin, the market-leading provider of Security Policy Orchestration Solutions, 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. As the market leader of Security Policy Orchestration, Tufin automates and accelerates network configuration changes while maintaining security and compliance. Tufin's award-winning Orchestration Suite™ gives IT organizations the power and agility to enforce security policy across complex, multi-vendor enterprise networks. With more than 1...
As enterprises move to all-IP networks and cloud-based applications, communications service providers (CSPs) – facing increased competition from over-the-top providers delivering content via the Internet and independently of CSPs – must be able to offer seamless cloud-based communication and collaboration solutions that can scale for small, midsize, and large enterprises, as well as public sector organizations, in order to keep and grow market share. The latest version of Oracle Communications Unified Communications Suite gives CSPs the capability to do just that. In addition, its integration ...
SYS-CON Events announced today that Cloudian, Inc., the leading provider of hybrid cloud storage solutions, 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. Cloudian, Inc., is a Foster City, California - based software company specializing in cloud storage software. The main product is Cloudian, an Amazon S3-compliant cloud object storage platform, the bedrock of cloud computing systems, that enables cloud service providers and enterprises to build reliable, affordable and scalable cloud storage solu...
SYS-CON Events announced today that Gridstore™, the leader in hyper-converged infrastructure purpose-built to optimize Microsoft workloads, 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. Gridstore™ is the leader in hyper-converged infrastructure purpose-built for Microsoft workloads and designed to accelerate applications in virtualized environments. Gridstore’s hyper-converged infrastructure is the industry’s first all flash version of HyperConverged Appliances that include both compute and storag...
SYS-CON Events announced today that IDenticard 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. IDenticard™ is the security division of Brady Corp (NYSE: BRC), a $1.5 billion manufacturer of identification products. We have small-company values with the strength and stability of a major corporation. IDenticard offers local sales, support and service to our customers across the United States and Canada. Our partner network encompasses some 300 of the world's leading systems integrators and security s...
BroadSoft on Tuesday announced that it is a recipient of the 2014 Frost & Sullivan Market Leadership Award in the Hosted/Cloud Internet Protocol (IP) Telephony market for Latin America. According to Frost & Sullivan market research, the Latin America (LATAM) hosted/cloud Internet Protocol (IP) telephony market, including integrated unified communications and collaboration (UC&C) applications, is currently experiencing a rapid growth trajectory and is expected to exhibit a tenfold rise in annual revenues in the 2013-2020 period. With more than 600 cloud deployments internationally, BroadSoft w...