RFR: 8298381: Improve handling of session tickets for multiple SSLContexts
Volker Simonis
simonis at openjdk.org
Tue Dec 20 23:50:15 UTC 2022
On Sun, 11 Dec 2022 20:38:16 GMT, Xue-Lei Andrew Fan <xuelei at openjdk.org> wrote:
>> Currently, TLS session tickets introduced by [JDK-8211018](https://bugs.openjdk.org/browse/JDK-8211018) in JDK 13 (i.e. `SessionTicketExtension$StatelessKey`) are generated in the class `SessionTicketExtension` and they use a single, global key ID (`currentKeyID`) for all `SSLContext`s.
>>
>> This is problematic if more than one `SSLContext` is used, because every context which requests a session ticket will increment the global id `currentKeyID` when it creates a ticket. This means that in turn all the other contexts won't be able to find a ticket under the new id in their `SSLContextImpl` and create a new one (again incrementing `currentKeyID`). In fact, every time a ticket is requested from a different context, this will transitively trigger a new ticket creation in all the other contexts. We've observed millions of session ticket accumulating for some workloads.
>>
>> Another issue with the curent implementation is that cleanup is racy because the underlying data structure (i.e. `keyHashMap` in `SSLContextImpl`) as well as the cleanup code itself are not threadsafe.
>>
>> I therefor propose to move `currentKeyID` into the `SSLContextImpl` to solve these issues.
>>
>> The following test program (contributed by Steven Collison (https://raycoll.com/)) can be used to demonstrate the current behaviour. It outputs the number of `StatelessKey` instances at the end of the program. Opening 1000 connections with a single `SSLContext` results in a single `StatelessKey` instance being created:
>>
>> $ java -XX:+UseSerialGC -Xmx16m -cp ~/Java/ SSLSocketServerMultipleSSLContext 9999 1 1000
>> 605: 1 32 sun.security.ssl.SessionTicketExtension$StatelessKey (java.base at 20-internal)
>>
>> The same example with the 1000 connections being opened alternatively on thwo different contexts will instead create 1000 `StatelessKey` instances:
>>
>> $ java -XX:+UseSerialGC -Xmx16m -cp ~/Java/ SSLSocketServerMultipleSSLContext 9999 2 1000
>> 11: 1000 32000 sun.security.ssl.SessionTicketExtension$StatelessKey (java.base at 20-internal)
>>
>> With my proposed patch, the numbers goes back to two instances again:
>>
>> $ java -XX:+UseSerialGC -Xmx16m -cp ~/Java/ SSLSocketServerMultipleSSLContext 9999 2 1000
>> 611: 2 64 sun.security.ssl.SessionTicketExtension$StatelessKey (java.base at 20-internal)
>>
>>
>> I've attached the test program to the [JBS issue](https://bugs.openjdk.org/browse/JDK-8298381). If you think it makes sense, I can probably convert it into a JTreg test.
>
>> The same example with the 1000 connections being opened alternatively on two different contexts will instead create 1000 `StatelessKey` instances:
>
> That's obviously not the expected behaviors. It is a good catch for the `static currentKeyID` issue.
>
> What do you think to move `SSLContextImpl.keyHashMap` into `SSLSessionContextImpl`? I would like to have SSLContextImpl focusing on configuration.
Hi @XueleiFan,
I've moved `keyHashMap` and `currentKeyID` into `SSLSessionContextImpl` as you've requested and also did some refactoring and simplification (i.e. moved most of the implementation from `SessionTicketExtension` to `SSLSessionContextImpl`).
Can you please have a look at the new version?
Thanks,
Volker
-------------
PR: https://git.openjdk.org/jdk/pull/11590
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