From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.codeaurora.org by pdx-caf-mail.web.codeaurora.org (Dovecot) with LMTP id JzcIG3lDGVviCAAAmS7hNA ; Thu, 07 Jun 2018 14:38:49 +0000 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 5E178608C1; Thu, 7 Jun 2018 14:38:49 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on pdx-caf-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by smtp.codeaurora.org (Postfix) with ESMTP id B26FD608BA; Thu, 7 Jun 2018 14:38:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org B26FD608BA Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934264AbeFGOio (ORCPT + 25 others); Thu, 7 Jun 2018 10:38:44 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:40483 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934131AbeFGOil (ORCPT ); Thu, 7 Jun 2018 10:38:41 -0400 Received: from [148.252.241.226] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.84_2) (envelope-from ) id 1fQvbJ-0005Zq-7y; Thu, 07 Jun 2018 15:09:17 +0100 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1fQvbF-0003Ih-3S; Thu, 07 Jun 2018 15:09:13 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "=?UTF-8?q?Linus=20L=C3=BCssing?=" , "Sven Eckelmann" , "Simon Wunderlich" Date: Thu, 07 Jun 2018 15:05:21 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 395/410] batman-adv: fix packet loss for broadcasted DHCP packets to a server In-Reply-To: X-SA-Exim-Connect-IP: 148.252.241.226 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.57-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Linus Lüssing commit a752c0a4524889cdc0765925258fd1fd72344100 upstream. DHCP connectivity issues can currently occur if the following conditions are met: 1) A DHCP packet from a client to a server 2) This packet has a multicast destination 3) This destination has a matching entry in the translation table (FF:FF:FF:FF:FF:FF for IPv4, 33:33:00:01:00:02/33:33:00:01:00:03 for IPv6) 4) The orig-node determined by TT for the multicast destination does not match the orig-node determined by best-gateway-selection In this case the DHCP packet will be dropped. The "gateway-out-of-range" check is supposed to only be applied to unicasted DHCP packets to a specific DHCP server. In that case dropping the the unicasted frame forces the client to retry via a broadcasted one, but now directed to the new best gateway. A DHCP packet with broadcast/multicast destination is already ensured to always be delivered to the best gateway. Dropping a multicasted DHCP packet here will only prevent completing DHCP as there is no other fallback. So far, it seems the unicast check was implicitly performed by expecting the batadv_transtable_search() to return NULL for multicast destinations. However, a multicast address could have always ended up in the translation table and in fact is now common. To fix this potential loss of a DHCP client-to-server packet to a multicast address this patch adds an explicit multicast destination check to reliably bail out of the gateway-out-of-range check for such destinations. The issue and fix were tested in the following three node setup: - Line topology, A-B-C - A: gateway client, DHCP client - B: gateway server, hop-penalty increased: 30->60, DHCP server - C: gateway server, code modifications to announce FF:FF:FF:FF:FF:FF Without this patch, A would never transmit its DHCP Discover packet due to an always "out-of-range" condition. With this patch, a full DHCP handshake between A and B was possible again. Fixes: be7af5cf9cae ("batman-adv: refactoring gateway handling code") Signed-off-by: Linus Lüssing Signed-off-by: Sven Eckelmann Signed-off-by: Simon Wunderlich [bwh: Backported to 3.16: Drop redundant change to initialisation] Signed-off-by: Ben Hutchings --- --- a/net/batman-adv/gateway_client.c +++ b/net/batman-adv/gateway_client.c @@ -804,6 +804,9 @@ bool batadv_gw_out_of_range(struct batad vid = batadv_get_vid(skb, 0); + if (is_multicast_ether_addr(ethhdr->h_dest)) + goto out; + orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source, ethhdr->h_dest, vid); if (!orig_dst_node)