This is an abstract class for representing the system policy for Subject-based authorization.

 

This is an abstract class for representing the system policy for Subject-based authorization. A subclass implementation of this class provides a means to specify a Subject-based access control Policy.

A Policy object can be queried for the set of Permissions granted to code running as a Principal in the following manner:

        policy = Policy.getPolicy();
        PermissionCollection perms = policy.getPermissions(subject,
                                                        codeSource);
 

The Policy object consults the local policy and returns and appropriate Permissions object with the Permissions granted to the Principals associated with the provided subject, and granted to the code specified by the provided codeSource.

A Policy contains the following information. Note that this example only represents the syntax for the default Policy implementation. Subclass implementations of this class may implement alternative syntaxes and may retrieve the Policy from any source such as files, databases, or servers.

Each entry in the Policy is represented as a grant entry. Each grant entry specifies a codebase, code signers, and Principals triplet, as well as the Permissions granted to that triplet.

        grant CodeBase ["URL"], Signedby ["signers"],
              Principal [Principal_Class] "Principal_Name" {
            Permission Permission_Class ["Target_Name"]
                                        [, "Permission_Actions"]
                                        [, signedBy "SignerName"];
        };
 

The CodeBase and Signedby components of the triplet name/value pairs are optional. If they are not present, then any any codebase will match, and any signer (including unsigned code) will match. For Example,

        grant CodeBase "foo.com", Signedby "foo",
              Principal com.sun.security.auth.SolarisPrincipal "duke" {
            permission java.io.FilePermission "/home/duke", "read, write";
        };
 

This grant entry specifies that code from "foo.com", signed by "foo', and running as a SolarisPrincipal with the name, duke, has one Permission. This Permission permits the executing code to read and write files in the directory, "/home/duke".

To "run" as a particular Principal, code invokes the Subject.doAs(subject, ...) method. After invoking that method, the code runs as all the Principals associated with the specified Subject. Note that this Policy (and the Permissions granted in this Policy) only become effective after the call to Subject.doAs has occurred.

Multiple Principals may be listed within one grant entry. All the Principals in the grant entry must be associated with the Subject provided to Subject.doAs for that Subject to be granted the specified Permissions.

        grant Principal com.sun.security.auth.SolarisPrincipal "duke",
              Principal com.sun.security.auth.SolarisNumericUserPrincipal "0" {
            permission java.io.FilePermission "/home/duke", "read, write";
            permission java.net.SocketPermission "duke.com", "connect";
        };
 

This entry grants any code running as both "duke" and "0" permission to read and write files in duke's home directory, as well as permission to make socket connections to "duke.com".

Note that non Principal-based grant entries are not permitted in this Policy. Therefore, grant entries such as:

        grant CodeBase "foo.com", Signedby "foo" {
            permission java.io.FilePermission "/tmp/scratch", "read, write";
        };
 

are rejected. Such permission must be listed in the java.security.Policy.

The default Policy implementation can be changed by setting the value of the "auth.policy.provider" security property (in the Java security properties file) to the fully qualified name of the desired Policy implementation class. The Java security properties file is located in the file named <JAVA_HOME>/lib/security/java.security. <JAVA_HOME> refers to the value of the java.home system property, and specifies the directory where the JRE is installed.