Java Security, 2nd Edition

Methods of the Security Manager

Now that we have an understanding of how the security manager works, we’ll look into what protection the security manager actually provides. We’ll discuss the public methods of the security manager that perform security checks and when those methods are called, along with the rationale behind each of the methods. Since these methods are all public, they can be called anywhere, including in your own code, although as we’ve mentioned, that’s a rare thing. The real point of this section is so that you can know which methods of the core Java API are affected by the security manager and to give you some background on why these choices were made.

When we discuss the methods below, we speak of them in terms of trusted and untrusted classes. A trusted class is a class of the core Java API or a class that has been granted explicit permission to perform the operation in question.

You’ll note that the methods of the security manager correspond fairly well to the set of default permissions that we listed in Chapter 2. In fact, the basic implementation of each method of the security manager is to test to ensure that each active protection domain has permission to perform the desired operation.

Methods Relating to File Access

The most well-known methods of the security manager class handle access to files on the local network. This includes any files that are on the local disk as well as files that might be physically located on another machine but appear (through ...