linux-kernel - Re: [PATCH] net/tcp: Only produce AO/MD5 logs if there are any keys

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Message-ID: <dca62206-165e-40bc-b834-0df2941fad41@arista.com>
Date: Thu, 4 Jan 2024 17:30:31 +0000
From: Dmitry Safonov <dima@...sta.com>
To: Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>
Cc: "David S. Miller" <davem@...emloft.net>, Paolo Abeni <pabeni@...hat.com>,
 Christian Kujau <lists@...dbynature.de>,
 Salam Noureddine <noureddine@...sta.com>, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org, Dmitry Safonov <0x7f454c46@...il.com>
Subject: Re: [PATCH] net/tcp: Only produce AO/MD5 logs if there are any keys

On 1/4/24 16:59, Eric Dumazet wrote:
> On Thu, Jan 4, 2024 at 5:59 PM Jakub Kicinski <kuba@...nel.org> wrote:
>>
>> On Thu, 4 Jan 2024 16:42:05 +0000 Dmitry Safonov wrote:
>>>>> Keep silent and avoid logging when there aren't any keys in the system.
>>>>>
>>>>> Side-note: I also defined static_branch_tcp_*() helpers to avoid more
>>>>> ifdeffery, going to remove more ifdeffery further with their help.
>>>>
>>>> Wouldn't we be better off converting the prints to trace points.
>>>> The chances for hitting them due to malicious packets feels much
>>>> higher than dealing with a buggy implementation in the wild.
>>>
>>> Do you mean a proper stuff like in net/core/net-traces.c or just
>>> lowering the loglevel to net_dbg_ratelimited() [like Christian
>>> originally proposed], which in turns becomes runtime enabled/disabled?
>>
>> I mean proper tracepoints.
>>
>>> Both seem fine to me, albeit I was a bit reluctant to change it without
>>> a good reason as even pre- 2717b5adea9e TCP-MD5 messages were logged and
>>> some userspace may expect them. I guess we can try and see if anyone
>>> notices/complains over changes to these messages changes or not.

[to add up context]
I supposed it's only tests that grep for those messages, but I've looked
up the code-base and it's wired up to daemon's code to monitor messages
with a "filter" for rsyslogd. Certainly not an issue for arista as there
are people maintaining that (and AFAIK, rasdaemon is already used for
other traces), but I guess provides grounds for my concerns over other
projects.

>> Hm. Perhaps we can do the conversion in net-next. Let me ping Eric :)
> 
> Sure, let's wait for the next release for a conversion, thanks !
> 
> Reviewed-by: Eric Dumazet <edumazet@...gle.com>

Thanks!

I'll do the conversion for net-next if you don't mind :-)

That will be pretty nice as it's going to be easy to exercise in tcp-ao
selftests. Grepping dmesg can't be selftested as reliably/non-flaky.

Thanks,
            Dmitry