netdev - Re: [PATCH v2 net] net/tls: fix encryption error checking

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Date:   Wed, 20 May 2020 01:49:33 +0300
From:   Vadim Fedorenko <vfedorenko@...ek.ru>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     Boris Pismenny <borisp@...lanox.com>,
        Aviad Yehezkel <aviadye@...lanox.com>,
        John Fastabend <john.fastabend@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH v2 net] net/tls: fix encryption error checking

On 20.05.2020 01:04, Jakub Kicinski wrote:
> On Tue, 19 May 2020 13:20:43 +0300 Vadim Fedorenko wrote:
>> bpf_exec_tx_verdict() can return negative value for copied
>> variable. In that case this value will be pushed back to caller
>> and the real error code will be lost. Fix it using signed type and
>> checking for positive value.
>>
>> Fixes: d10523d0b3d7 ("net/tls: free the record on encryption error")
>> Fixes: d3b18ad31f93 ("tls: add bpf support to sk_msg handling")
>> Signed-off-by: Vadim Fedorenko <vfedorenko@...ek.ru>
> If the error encountered is transient we will still drop some data from
> the stream, because the record that was freed may have included data
> from a previous send call. Still, cleaning up the error code seems like
> an improvement.
>
> John, do you have an opinion on this?

Jakub, maybe it is better to free only in case of fatal encryption error? I mean
when sk->sk_err is EBADMSG. Because in case of ENOMEM we will iterate to
alloc_payload and in case of ENOSPC we will return good return code and send
open_rec again on next call. The EBADMSG state is the only fatal state that needs
freeing of allocated record.