linux-kernel - Re: [PATCH 00/19] tcp: Initial support for RFC5925 auth option

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Message-ID: <b6c15f48-b6d1-e656-c796-9e7e63e646b3@gmail.com>
Date:   Sat, 25 Sep 2021 17:21:14 +0300
From:   Leonard Crestez <cdleonard@...il.com>
To:     David Ahern <dsahern@...il.com>,
        Francesco Ruggeri <fruggeri@...sta.com>
Cc:     Dmitry Safonov <0x7f454c46@...il.com>,
        David Ahern <dsahern@...nel.org>,
        Shuah Khan <shuah@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        "David S. Miller" <davem@...emloft.net>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Kuniyuki Iwashima <kuniyu@...zon.co.jp>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Jakub Kicinski <kuba@...nel.org>,
        Yuchung Cheng <ycheng@...gle.com>,
        Mat Martineau <mathew.j.martineau@...ux.intel.com>,
        Christoph Paasch <cpaasch@...le.com>,
        Ivan Delalande <colona@...sta.com>,
        Priyaranjan Jha <priyarjha@...gle.com>,
        netdev <netdev@...r.kernel.org>, linux-crypto@...r.kernel.org,
        linux-kselftest@...r.kernel.org,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 00/19] tcp: Initial support for RFC5925 auth option



On 9/25/21 4:35 AM, David Ahern wrote:
> On 9/23/21 1:38 AM, Leonard Crestez wrote:
>> On 9/22/21 11:23 PM, Francesco Ruggeri wrote:
>>> On Tue, Sep 21, 2021 at 9:15 AM Leonard Crestez <cdleonard@...il.com>
>>> wrote:
>>>> * Sequence Number Extension not implemented so connections will flap
>>>> every ~4G of traffic.
>>>
>>> Could you expand on this?
>>> What exactly do you mean by flap? Will the connection be terminated?
>>> I assume that depending on the initial sequence numbers the first flaps
>>> may occur well before 4G.
>>> Do you use a SNE of 0 in the hash computation, or do you just not include
>>> the SNE in it?
>>
>> SNE is hardcoded to zero, with the logical consequence of incorrect
>> signatures on sequence number wrapping. The SNE has to be included
>> because otherwise all signatures would be invalid.
>>
>> You are correct that this can break much sooner than 4G of traffic, but
>> still in the GB range on average. I didn't test the exact behavior (not
>> clear how) but if signatures don't validate the connection will likely
>> timeout.
>>
> 
> This is for BGP and LDP connections. What's the expected frequency of
> rollover for large FIBs? Seems like it could be fairly often.

Implementing SNE is obviously required for standard conformance, I'm not 
claiming it is not needed. I will include this in a future version.

I skipped it because it has very few interactions with the rest of the 
code so it can be implemented separately. Many tests can pass just fine 
ignoring SNE.

--
Regards,
Leonard