JEP 411: Deprecation with removal would break most existing Java libraries

[Peter Firmstone]

My thoughts on how to proceed with this is:

 1. Develop authorization layer security provider services in OpenJDK,
    back port it to Java 8 and Java 11 (these provide most of the
    utilised functionality of SecurityManager, allowing developers to
    only implement those which they need, without enabling
    SecurityManager and editing policy files).
 2. Remove SecurityManager, Policy and Policy provider in OpenJDK 19.
 3. Leave AccessController and AccessControlContext in place, provide a
    security property that allows the stack walk to be disabled (One
    ProtectionDomain to represent all code in JVM, without any
    permissions, later making it the default, while allowing it to be
    enabled) and continue to inject user Subject principles using
    SubjectDomainCombiner for JAAS compatibility. Developers can
    implement just the authorization they feel necessary for users and
    develop their own configuration, or adapt existing.
 4. At some point, preferably when StackWalker has equivalent
    performance, replace the internals of AccessController.

Gut feel is that removal of AccessController, AccessControlContext and 
DomainCombiner causes carnage with JAAS, it's a lot to deal with, 
SecurityManager and Policy, I don't need them if I've got authorization 
layer hooks in the JVM.

I wouldn't want to see SecurityManager and Policy be neutralized, it's 
better to remove it and fail early so people update their software, 
there's a risk they may update without realizing it's no longer fully 
functional.   Get rid of the baggage so people can start fresh with 
better practices.

Note that I'll be implementing a full authorization layer based on least 
privilege principles, that still utilizes a stack walk. I won't use the 
standard Java Permission implementations, as I'd like to do things a 
little differently, for usability reasons, this will do everything I 
need at least.  If the authorization layer is back ported, then I can 
support all current versions. My policy files are generated, so I don't 
need permission implementations to remain compatible.

Whatever happens with JAAS will need to be backported, so we can support 
all versions.

Regards,

Peter.

On 14/06/2021 3:54 pm, Alan Bateman wrote:
> cc'ing security-dev as that is the mailing list to use for this JEP.
>
> This JEP is the first of several in a multi-release/multi-year effort. 
> It's way too early to give any guess as to when the APIs will be 
> removed. As the JEP says, future releases may degrade the SM APIs so 
> that System.getSM returns always returns null or 
> AccessController::doPriv just runs the action. This should mean that 
> libraries that are compiling to older releases should continue to 
> compile and run on those releases. When they run on some future 
> release that degrades the implementation then it will be as if there 
> is no SM.  So I would say the impact is little to none for libraries 
> for the foreseeable future.
>
> -Alan
>
>
> On 13/06/2021 21:28, Rafael Winterhalter wrote:
>> I am currently looking into how I should address JEP 411 in my 
>> library Byte
>> Buddy and I find it rather challenging. The problem I am facing is 
>> that I
>> know of several users who rely on the security manager in their Java 
>> 8/11
>> applications. I would like to continue to support those users' use 
>> cases as
>> long as I support Java versions that contain the security manager, which
>> will be for many years to come. At the same time, I would like to 
>> address
>> the announced removal of the API and make sure that Byte Buddy can work
>> without it prior to the deadline when the library in its current state
>> would no longer link.
>>
>>  From my understanding of the intention of JEP 411, the API was 
>> supposed to
>> be stubbed – similar to Android’s stubbing of the API - rather than 
>> being
>> removed. However, with the announced deprecation for removal of
>> AccessController and SecurityManager, I understand that I would need to
>> fully remove the dispatching to work with future Java versions.
>>
>> Furthermore, it is difficult to create a working facade for 
>> dispatching to
>> the security manager only if it is available. Methods like
>> AccessController.doPrivileged are caller sensitive and by adding a 
>> utility
>> to a library, this utility would leak to any potential user. It would
>> therefore require package-private dispatchers for any relevant package,
>> which would lead to a lot of copy-paste to retain backwards 
>> compatibility
>> (given that a library cannot assume to be run as a module).
>>
>> Finally, removing the API would mean that Byte Buddy versions of the 
>> last
>> ten years would no longer link in future JDKs. For Byte Buddy where new
>> Java versions often require an update, that might not be a big issue but
>> many other libraries do support the API, I don’t feel it would be a 
>> rather
>> severe restriction and cause unnecessary breakage if API is removed, 
>> rather
>> than stubbed. I am thinking of libraries like Netty here which are 
>> rather
>> omnipresent and would suddenly no longer link, a concept that is 
>> unlikely
>> intuitive to a lot of developers.
>>
>> Therefore, my question is: should SecurityManager, AccessController 
>> and the
>> Policy APIs really be deprecated for removal? Rather, I think that 
>> the APIs
>> should be deprecated, but be retained with stubbed implementations.
>> System.getSecurityMananger would then always return null.
>> System.setSecurityManager on the other hand could be deprecated for
>> removal. This way, existing code could continue to work as if the 
>> security
>> manager is not active, which already is the common scenario and would 
>> not
>> cause any disruption at the small price of keeping a handful of some
>> stubbed classes.
>>
>> Thanks for advice on how this is intended to be handled by library
>> developers like me.
>> Best regards, Rafael
>
-- 
Regards,
  
Peter Firmstone
0498 286 363
Zeus Project Services Pty Ltd.

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