netdev - RE: [PATCH 0/2] tls, add unhash callback

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Date:   Thu, 27 Jun 2019 11:16:07 -0700
From:   John Fastabend <john.fastabend@...il.com>
To:     John Fastabend <john.fastabend@...il.com>, daniel@...earbox.net,
        jakub.kicinski@...ronome.com, ast@...nel.org
Cc:     netdev@...r.kernel.org, edumazet@...gle.com,
        john.fastabend@...il.com, bpf@...r.kernel.org
Subject: RE: [PATCH 0/2] tls, add unhash callback

John Fastabend wrote:
> Resolve a series of splats discovered by syzbot and noted by
> Eric Dumazet. The primary problem here is we resolved an issue on
> the BPF sockmap side by adding an unhash callback. This is
> required to ensure sockmap sockets do not transition out of
> ESTABLISHED state into a LISTEN state. When we did this it
> created a case where the interaction between callbacks in TLS
> and sockmap when used together could break. This resulted in
> leaking TLS memory and potential to build loops of callbacks
> where sockmap called into TLS and TLS called back into BPF.
> 
> Additionally, TLS was releasing the sock lock and then
> reaquiring it during the tear down process which could hang
> if another sock operation happened while the lock was not
> held.
> 
> To fix this first refactor TLS code so lock is held for the
> entire teardown operation. Then add an unhash callback to ensure
> TLS can not transition from ESTABLISHED to LISTEN state. This
> transition is a similar bug to the one found and fixed previously
> in sockmap. And cleans up the callbacks to fix the syzbot
> errors.
> 
> ---
>

Jakub,

If you could test this for the offload case that would
be helpful. I don't have any hardware here. We will still need
a few fixes in the unhash/hardware case but would be good to
know we don't cause any regressions here.

Thanks,
John