From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2F04AC433ED for ; Wed, 7 Apr 2021 10:19:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0FFB56113B for ; Wed, 7 Apr 2021 10:19:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350854AbhDGKUC (ORCPT ); Wed, 7 Apr 2021 06:20:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49222 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233283AbhDGKUB (ORCPT ); Wed, 7 Apr 2021 06:20:01 -0400 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [IPv6:2001:4d48:ad52:32c8:5054:ff:fe00:142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 18C7AC061756 for ; Wed, 7 Apr 2021 03:19:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:To:From:Date:Reply-To:Cc: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=0ubU+S206yyBNnPlxXi3JDbjQjgFzpSPDz3I7WoiVRk=; b=LzZhV0sdRz5ShPPG5v2ItJGI2 0C/E30SWWUKn86IjubZQ6E/FysCLOwPxLBUn9UofIiesJLsMXGfEcOpRp+oQl2G5+3wULrCpH7DIF Tc57A5u38J59Z6o5jVzmEN/fDIdSwmmeavbXNeMSiwMsa1son7iUkZwk6s5UWt6q9TtbwMXve55U1 CfM/ZvRwkoDZ8F57yGCLxaH3KWHGni/7dDbbV0RlTuXmgjyrB5o1MbY6fW9vXflM3ko1V4T/r4QDw 3Bca0tWYWfjSSxrybjva0q5tlgtiGvpK0F2BXhjMrzNizvAJfbWNgFr6rnnSr2f7MF6HalWBeVveH T30dY9J7A==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:52180) by pandora.armlinux.org.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1lU5Hq-00089q-NU for netdev@vger.kernel.org; Wed, 07 Apr 2021 11:19:50 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1lU5Hq-0001uh-Fe for netdev@vger.kernel.org; Wed, 07 Apr 2021 11:19:50 +0100 Date: Wed, 7 Apr 2021 11:19:50 +0100 From: Russell King - ARM Linux admin To: netdev@vger.kernel.org Subject: Re: Semantics of AF_PACKET sockets on bridge port interface - patch Message-ID: <20210407101950.GG1477@shell.armlinux.org.uk> References: <20210403095418.GC1463@shell.armlinux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210403095418.GC1463@shell.armlinux.org.uk> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: Russell King - ARM Linux admin Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Sat, Apr 03, 2021 at 10:54:18AM +0100, Russell King - ARM Linux admin wrote: > Hi, > > This question has probably come up several times before, but there > doesn't seem to be a solution yet. > > Scenario: a network interface, such as a wireless adapter or a > network interface supporting PTP, is part of a bridge. Userspace > wishes to capture packets sent using a specific Ethernet protocol > to the ethernet address of that network interface, such as EAPOL > frames or PTP frames. > > Problem 1: __netif_receive_skb_core() scans the global ptype_all and > skb->dev->ptype_all lists to deliver to any packet capture sockets, > then checks skb->dev->rx_handler (which bridge sets), and from which > it returns RX_HANDLER_CONSUMED from. This bypasses AF_PACKET listeners > attached via the ->ptype_specific list, resulting in such a socket > not receiving any packets. > > Problem 2: detecting the port being a bridge port, and having the > application also bind to the bridge interface is not a solution; the > bridge can have a different MAC address to the bridge interface, so > e.g. EAPOL frames sent to the WiFi MAC address will not be routed to > the bridge interface. (hostapd does this but it's fragile for this > reason, and it doesn't work for ptp nor does it work for Network > Manager based bridged Wi-Fi which uses wpa_supplicant.) > > So, this problem really does need solving, but it doesn't look to be > trivial. Moving the scanning of the device's ptype_specific list > has implications for ingress and vlan handling. > > I'm aware of a large patch set in 2019 that contained a single patch > that claimed to fix it, but it looks like it was ignored, which is > not surprising given the size and content of the series. > https://lore.kernel.org/patchwork/patch/1066146/ > This patch no longer applies to current kernels since the bridge code > has changed, and in any case, I suspect the fix is wrong. > > Is there a solution for this, or are AF_PACKET ethernet-protocol > specific sockets just not supportable on bridge ports? The patch below is a hack I've tried to fix this problem, and with this I can configure a Wi-Fi AP in Network Manager beneath a bridge, and have it accept clients onto the network. Without this patch, they fail while trying to complete the EAPOL authentication. This setup uses wpa_supplicant attached to the Wi-Fi interface which has no knowledge that the interface is attached to a bridge. diff --git a/net/core/dev.c b/net/core/dev.c index 449b45b843d4..41f9ce764654 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -5208,6 +5208,10 @@ static int __netif_receive_skb_core(struct sk_buff **pskb, bool pfmemalloc, goto out; } + type = skb->protocol; + deliver_ptype_list_skb(skb, &pt_prev, orig_dev, type, + &orig_dev->ptype_specific); + rx_handler = rcu_dereference(skb->dev->rx_handler); if (rx_handler) { if (pt_prev) { @@ -5276,9 +5280,6 @@ static int __netif_receive_skb_core(struct sk_buff **pskb, bool pfmemalloc, PTYPE_HASH_MASK]); } - deliver_ptype_list_skb(skb, &pt_prev, orig_dev, type, - &orig_dev->ptype_specific); - if (unlikely(skb->dev != orig_dev)) { deliver_ptype_list_skb(skb, &pt_prev, orig_dev, type, &skb->dev->ptype_specific); -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!