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smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=enXb5x+0; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 82CBA606A322 for ; Tue, 27 Oct 2026 13:42:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=enXb5x+0 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2BF231F01825; Tue, 27 Oct 2026 13:42:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793108523; bh=0o1IrJTUNX+1Hnp/7kuO0LUiqsxuBZ70eMNrzlpuJgw=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=enXb5x+0IrE8FD89vtzppoV9U6MGGlwT/RzrcqxeKmV3cnWsk58P4nYpjuWgYYNLR 26r/9w+uiDiDJr4qsTSQnqQBWupMRdhgBSdiUeEk1QRvoKquyLc7tWlmnqrIMhRjER XKrCeEWORNALxXN90BWxrs75C0/2q5GZXWJ+RZuV65N9kZ856Sh89L0AwfWWZMYeUj z7HfwnhlhnBfkrInTmadPMdDGbMMzGM5PS61trjckOHACww0wg2lOIauqXbU1BXGz1 laTVq4E5GJybvePJ5+S0t+VSCilNoViUf9UlrY1GLJETfu7FtbV0jth05XcElBTtLm DlBGzu+d06QkQ== Message-ID: <1ec0c2b5-a0fa-44e8-9ae8-dca9b7f90ec6@kernel.org> Date: Tue, 27 Oct 2026 14:42:00 +0100 X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [RFC net-next v10] mptcp: normalize seq numbers reported in mptcp_info Content-Language: fr To: Kalpan Jani Cc: mptcp , martineau , pabeni References: <20261027062750.2095515-1-kalpan.jani@mpiricsoftware.com> <20261027095410.3675317-1-kalpan.jani@mpiricsoftware.com> <1a17d565bd7.51ae4f93484769.4801857719496061627@mpiricsoftware.com> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Kalpan, Thank you for your reply. On 27/10/2026 13:29, Kalpan Jani wrote: > Hi Matt, > > I investigated the existing byte counters and the diagnostic > capability path. > > The existing byte counters are not direct replacements for the > normalized sequence fields: > > - write_seq advances when application data is queued and when > DATA_FIN is added. bytes_sent tracks send progress, and the > retransmission path can update snd_nxt directly without updating > bytes_sent. - snd_una is assigned directly during connection setup, > outside __mptcp_snd_una_update(). Therefore, bytes_acked cannot be > assumed to reproduce snd_una - local_idsn. - ack_seq advances when > processing DATA_FIN, whereas bytes_received counts payload bytes. > Their initial values also differ. OK, let's not use the bytes counters then. > Regarding the capability check, the normal MPTCP diagnostic dump > paths have access to the original request skb and can check > netlink_net_capable(cb->skb, CAP_NET_ADMIN). Good! > However, inet_diag_handler_get_info() is also called for socket- > destruction notifications. In that path, > sock_diag_broadcast_destroy_work() creates a new skb and invokes the > callback without an original diagnostic request. Therefore, the > requester's capability cannot be recovered from that skb. Passing > false in this notification path appears to be the appropriate > conservative behavior. OK to pass false in this case. > Based on this investigation, I will keep the capability/privacy > change separate from sequence normalization. I will also address the > stale remote_idsn after disconnect and the inconsistent sequence > snapshot reported by Sashiko before sending another normalization > revision. Just to be sure it is clear: the main goal here is not to show the seq counters to everybody from the same netns. This can be done either by "normalising" them -- i.e. starting from 0 -- or by not presenting them to some users. Just thinking about that: for the normalisation, we can also just add/remove an offset the userspace cannot predict and different per connection. In fact, why not using the address of the msk pointer? I guess that should prevent the different issues reported by Sashiko, no? (In case of "other" existing issues, please split them and move them in a dedicated patch not to mix the fix and the main patch here.) If the "normalisation" is not possible, better not displaying them to non cap-admin users. But we don't need both. Cheers, Matt -- Sponsored by the NGI0 Core fund.