Return-path: Received: from mail-qk0-f173.google.com ([209.85.220.173]:34019 "EHLO mail-qk0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751997AbeB1Lbf (ORCPT ); Wed, 28 Feb 2018 06:31:35 -0500 Received: by mail-qk0-f173.google.com with SMTP id l206so2508398qke.1 for ; Wed, 28 Feb 2018 03:31:35 -0800 (PST) Subject: Re: Problem with bridge (mcast-to-ucast + hairpin) and Broadcom's 802.11f in their FullMAC fw To: =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= , =?UTF-8?Q?Linus_L=c3=bcssing?= , Felix Fietkau , Franky Lin , Hante Meuleman , Chi-Hsien Lin , Wright Feng , Pieter-Paul Giesberts References: <88d080df-4cce-98d1-6482-0408a3dcb015@gmail.com> Cc: Network Development , bridge@lists.linux-foundation.org, "linux-wireless@vger.kernel.org" , "open list:BROADCOM BRCM80211 IEEE802.11n WIRELESS DRIVER" , brcm80211-dev-list@cypress.com From: Arend van Spriel Message-ID: <5A969313.5050501@broadcom.com> (sfid-20180228_123144_060953_551CD6DA) Date: Wed, 28 Feb 2018 12:31:31 +0100 MIME-Version: 1.0 In-Reply-To: <88d080df-4cce-98d1-6482-0408a3dcb015@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Sender: linux-wireless-owner@vger.kernel.org List-ID: On 2/27/2018 11:14 AM, Rafał Miłecki wrote: > Sending with a fixed linux-wireless ML address. Please kindly send your > replies using linux-wireless@ > > On 02/27/2018 11:08 AM, Rafał Miłecki wrote: >> I've problem when using OpenWrt/LEDE on a home router with Broadcom's >> FullMAC WiFi chipset. >> >> >> First of all OpenWrt/LEDE uses bridge interface for LAN network with: >> 1) IFLA_BRPORT_MCAST_TO_UCAST >> 2) Clients isolation in hostapd >> 3) Hairpin mode enabled >> >> For more details please see Linus's patch description: >> https://patchwork.kernel.org/patch/9530669/ >> and maybe hairpin mode patch: >> https://lwn.net/Articles/347344/ >> >> Short version: in that setup packets received from a bridged wireless >> interface can be handled back to it for transmission. >> >> >> Now, Broadcom's firmware for their FullMAC chipsets in AP mode >> supports an obsoleted 802.11f AKA IAPP standard. It's a roaming >> standard that was replaced by 802.11r. >> >> Whenever a new station associates, firmware generates a packet like: >> ff ff ff ff ff ff ec 10 7b 5f ?? ?? 00 06 00 01 af 81 01 00 >> (just masked 2 bytes of my MAC) >> >> For mode details you can see discussion in my brcmfmac patch thread: >> https://patchwork.kernel.org/patch/10191451/ >> >> >> The problem is that bridge (in setup as above) handles such a packet >> back to the device. From reading the referenced links I understand the hairpin mode is causing the packet to be sent back to the device, and the hairpin mode is required for MCAST_TO_UCAST, right? >> That makes Broadcom's FullMAC firmware believe that a given station >> just connected to another AP in a network (which doesn't even exist). >> As a result firmware immediately disassociates that station. It's >> simply impossible to connect to the router. Every association is >> followed by immediate disassociation. >> >> >> Can you see any solution for this problem? Is that an option to stop >> multicast-to-unicast from touching 802.11f packets? Some other ideas? >> Obviously I can't modify Broadcom's firmware and drop that obsoleted >> standard. As far as I can tell you are correct that the 802.11f amendment was never adopted into the 802.11 standard. I will ask internally if we still have a reason for carrying it in our firmware. Regards, Arend