From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CFBFE281349; Thu, 13 Feb 2025 14:43:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739457808; cv=none; b=lH9OBglYw4XFmZl9hNu8mJrykpThf/Erf612rM9lBbmM1PO33bx7o0ajY5v/qPADTGmhqo7d/P845jF6FiEf/eXR1jt9b1iSnxrGXKvcFWAOhyPnJgmEIaDcChJOJiKFdONq6UNIF/oZCewoiYNO7eJOcFBesYAm3GKrPKPHag8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739457808; c=relaxed/simple; bh=Bem96vx1EX5S0Doty1hQeiq5gwCpKG58PtsnUfS9Hzk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=eVldntBVBVser752D5KvQhf9cLFK/0oVBorgjUQZ3EzOeSLrRWayV7DRCDDq3IdPFZLu83/T4vATlhr8Myiz/lNZVPXeTtebQDrB9F3Wd9i3miJF2xkCFxTn0bIST9XiuPfM9FP43Xze8u5npcgLyBlK8q6EUcdQ5lS89pBaO/U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=vqAIlZJi; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="vqAIlZJi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C44ACC4CED1; Thu, 13 Feb 2025 14:43:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1739457808; bh=Bem96vx1EX5S0Doty1hQeiq5gwCpKG58PtsnUfS9Hzk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vqAIlZJi7MGe920Xz6FdGHXki/lO1/nxRc0gDWiJmF1MVVBS/KsT2L2OqZa1THt+s ujDV9k72Egre5BIAlOMORaOqaDTj0RQbCEGyHLeOmCZQM0akhbtJ/ayF3zusMamvpq YH9j8I9bAGKSOyS8A51wFeRy2bKPUrzs0g7GvdfA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Foster Snowhill , Jakub Kicinski , Paolo Abeni Subject: [PATCH 6.12 218/422] usbnet: ipheth: document scope of NCM implementation Date: Thu, 13 Feb 2025 15:26:07 +0100 Message-ID: <20250213142444.950214820@linuxfoundation.org> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250213142436.408121546@linuxfoundation.org> References: <20250213142436.408121546@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Foster Snowhill commit be154b598fa54136e2be17d6dd13c8a8bc0078ce upstream. Clarify that the "NCM" implementation in `ipheth` is very limited, as iOS devices aren't compatible with the CDC NCM specification in regular tethering mode. For a standards-compliant implementation, one shall turn to the `cdc_ncm` module. Cc: stable@vger.kernel.org # 6.5.x Signed-off-by: Foster Snowhill Reviewed-by: Jakub Kicinski Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman --- drivers/net/usb/ipheth.c | 8 ++++++++ 1 file changed, 8 insertions(+) --- a/drivers/net/usb/ipheth.c +++ b/drivers/net/usb/ipheth.c @@ -218,6 +218,14 @@ static int ipheth_rcvbulk_callback_legac return ipheth_consume_skb(buf, len, dev); } +/* In "NCM mode", the iOS device encapsulates RX (phone->computer) traffic + * in NCM Transfer Blocks (similarly to CDC NCM). However, unlike reverse + * tethering (handled by the `cdc_ncm` driver), regular tethering is not + * compliant with the CDC NCM spec, as the device is missing the necessary + * descriptors, and TX (computer->phone) traffic is not encapsulated + * at all. Thus `ipheth` implements a very limited subset of the spec with + * the sole purpose of parsing RX URBs. + */ static int ipheth_rcvbulk_callback_ncm(struct urb *urb) { struct usb_cdc_ncm_nth16 *ncmh;