[PATCH 0/4][SRU][focal:linux] NFSv4.1: Don't rebind to the same source port when reconnecting to the server

[Khaled Elmously]

On 2022-11-22 13:39:10 , Tim Gardner wrote:
> BugLink: https://bugs.launchpad.net/bugs/1997488
> 
> SRU Justification
> 
> Microsoft asked for this backport complaining that, 
> "NFS 4.1 mounts on AKS are reusing the same source port when a reconnect needs to happen".
> 
> Patches 1-3 are scaffolding in order to provide a clean cherrypick for patch 4.
> This issue looks applicable to the generic kernel.
> 
> [Impact]
> 
> NFSv2, v3 and NFSv4 servers often have duplicate replay caches that look
> at the source port when deciding whether or not an RPC call is a replay
> of a previous call. This requires clients to perform strange TCP gymnastics
> in order to ensure that when they reconnect to the server, they bind
> to the same source port.
> 
> NFSv4.1 and NFSv4.2 have sessions that provide proper replay semantics,
> that do not look at the source port of the connection. This patch therefore
> ensures they can ignore the rebind requirement.
> 
> [Where things could go wrong]
> 
> NFS reconnects may erroneously fail.
> 
> [Other Info]
> 
> SF: #00345839
> 

Would this not cause issues for users that run NFSv < 4.1 who don't have proper replay semantics and still rely on source-port reuse?




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