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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=B6cFrH79; 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 C66BC606A31A for ; Wed, 28 Oct 2026 09:43:09 +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=B6cFrH79 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 659601F031E0; Wed, 28 Oct 2026 09:43:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793180589; bh=rjDpvyNt0phDIHUyQVwffTSDLVXB6H+hthcHEgkFXIU=; h=Date:Subject:From:To:Cc:References:In-Reply-To; b=B6cFrH79/hwSNUFG3nl+bZ2svPtV1RuwLFVXw1FJdvR/u4Zl19Qq5tJhpzi6TrQV1 hxwe1qvovVQSOFBy8L6zPsW5Wb5TRfwlY7NyoYxFRKRdY0brNBPV4pkfS3XbJ7LgeW jhbgOWpGpLC7OeLxRK1lozfdRIjB8MdkD3iBhKGGYv0PCAsa2G1l0uFeO3sPR91fHp myumsFnfPW8a1sFZPPNTUXtfIDYexyZVk0OZiwC+3uTPC6oEsfQssKCsf0y3NFc7qf 7PZnsxOjhVcLP/1AwV1yLZ9vqLe00IX+gSV+bx5d8NYDWqe896nzotUSSEu7/BqX59 qY7+flBqEpVjw== Message-ID: <495a89c5-40ca-4758-8366-6c4c28e28112@kernel.org> Date: Wed, 28 Oct 2026 10:43:05 +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 From: Matthieu Baerts 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> <1ec0c2b5-a0fa-44e8-9ae8-dca9b7f90ec6@kernel.org> Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Kalpan, On 27/10/2026 14:42, Matthieu Baerts wrote: > 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? Was this workaround using the msk address not working? BTW, please next time don't send new series as a reply to an email, start a new email thread instead. > (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 Cheers, Matt -- Sponsored by the NGI0 Core fund.