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Subject: Re: [PATCH] net/tls: support SM4 CCM algorithm
To:     Tianjia Zhang <tianjia.zhang@linux.alibaba.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Boris Pismenny <borisp@nvidia.com>,
        John Fastabend <john.fastabend@gmail.com>,
        Daniel Borkmann <daniel@iogearbox.net>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20210928062843.75283-1-tianjia.zhang@linux.alibaba.com>
 <1761d06d-0958-7872-04de-cde6ddf8a948@novek.ru>
 <1195374a-a9d4-0431-015b-60d986e29881@linux.alibaba.com>
From:   Vadim Fedorenko <vfedorenko@novek.ru>
Message-ID: <16a76d3e-910f-4fdf-5b2d-9f3355cce4ca@novek.ru>
Date:   Thu, 30 Sep 2021 23:56:13 +0100
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On 30.09.2021 04:34, Tianjia Zhang wrote:
> Hi Vadim,
> 
> On 9/29/21 5:24 AM, Vadim Fedorenko wrote:
>> On 28.09.2021 07:28, Tianjia Zhang wrote:
>>> The IV of CCM mode has special requirements, this patch supports CCM
>>> mode of SM4 algorithm.
>>>
>> Have you tried to connect this implementation to application with
>> user-space implementation of CCM mode? I wonder just because I have an
>> issue with AES-CCM Kernel TLS implementation when it's connected to
>> OpenSSL-driven server, but still have no time to fix it correctly.
> 
> I did not encounter any issue when using KTLS with AES-CCM algorithm, but the 
> KTLS RX mode on the OpenSSL side does not seem to be supported.
> 
> I encountered some problems when using the SM4-CCM algorithm of KTLS. Follow the 
> RFC8998 specification, the handshake has been successful, and the first data 
> transmission can be successful. After that, I will encounter the problem of MAC 
> verification failure, but this is issue on the OpenSSL side. because the problem 
> is still being investigated, I have not opened the code for the time being.
> 
Are you sure that this is an issue on the OpenSSL side? Because absolutely the 
same problem is reported for AES-CCM algo and only when it's offloaded to 
kernel. Looks like encryption of CCM could be broken somehow.

I will try to investigate it a bit later from the AES-CCM side.