RFR: 8298381: Improve handling of session tickets for multiple SSLContexts

Xue-Lei Andrew Fan xuelei at openjdk.org
Sun Dec 11 20:40:39 UTC 2022


On Thu, 8 Dec 2022 13:09:11 GMT, Volker Simonis <simonis 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.

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PR: https://git.openjdk.org/jdk/pull/11590


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