RFR: 8296244: Alternate implementation of user-based authorization Subject APIs that doesn’t depend on Security Manager APIs [v3]

[Sean Mullan]

On Tue, 30 Jan 2024 21:58:28 GMT, Weijun Wang <weijun at openjdk.org> wrote:

>> This code change adds an alternative implementation of user-based authorization `Subject` APIs that doesn't depend on Security Manager APIs. Depending on if the Security Manager is allowed, the methods store the current subject differently. See the spec change in the `Subject.java` file for details. When the Security Manager APIs are finally removed in a future release, this new implementation will be only implementation for these methods.
>> 
>> One major change in the new implementation is that `Subject.getSubject` always throws an `UnsupportedOperationException` since it has an `AccessControlContext` argument but the current subject is no longer associated with an `AccessControlContext` object.
>> 
>> Now it's the time to migrate from the `getSubject` and `doAs` methods to `current` and `callAs`. If the user application is simply calling `getSubject(AccessController.getContext())`, then switching to `current()` would work. If the `AccessControlContext` argument is retrieved from an earlier `getContext()` call and the associated subject might be different from that of the current `AccessControlContext`, then instead of storing the previous `AccessControlContext` object and passing it into `getSubject` to get the "previous" subject, the application should store the `current()` return value directly.
>
> Weijun Wang has updated the pull request incrementally with one additional commit since the last revision:
> 
>   fix MBeanServerFileAccessController, more test in SM

src/java.management/share/classes/com/sun/jmx/remote/security/MBeanServerFileAccessController.java line 309:

> 307:         final Subject s;
> 308:         if (!SharedSecrets.getJavaLangAccess().allowSecurityManager()) {
> 309:             s = Subject.current();

We may not want to call `Subject.current()` here, as this may imply that we will support this functionality even if an SM is not enabled.

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PR Review Comment: https://git.openjdk.org/jdk/pull/17472#discussion_r1511351340