From patchwork Thu Mar 16 13:34:29 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Simon Wunderlich X-Patchwork-Id: 16980 Return-Path: X-Original-To: patchwork@open-mesh.org Delivered-To: patchwork@open-mesh.org Received: from open-mesh.org (localhost [IPv6:::1]) by open-mesh.org (Postfix) with ESMTP id DB0C283692; Thu, 16 Mar 2017 14:35:27 +0100 (CET) Authentication-Results: open-mesh.org; dmarc=none header.from=simonwunderlich.de Received-SPF: Pass (sender SPF authorized) identity=mailfrom; client-ip=79.140.42.25; helo=mail.mail.packetmixer.de; envelope-from=sw@simonwunderlich.de; receiver=b.a.t.m.a.n@lists.open-mesh.org Authentication-Results: open-mesh.org; dmarc=none header.from=simonwunderlich.de Received: from mail.mail.packetmixer.de (packetmixer.de [79.140.42.25]) by open-mesh.org (Postfix) with ESMTPS id E5EB083625 for ; Thu, 16 Mar 2017 14:34:40 +0100 (CET) Received: from kero.packetmixer.de (p2003007C6F58B00094A5DD1D27095BA3.dip0.t-ipconnect.de [IPv6:2003:7c:6f58:b000:94a5:dd1d:2709:5ba3]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.mail.packetmixer.de (Postfix) with ESMTPSA id 9D666622F4; Thu, 16 Mar 2017 14:34:40 +0100 (CET) From: Simon Wunderlich To: b.a.t.m.a.n@lists.open-mesh.org Date: Thu, 16 Mar 2017 14:34:29 +0100 Message-Id: <20170316133429.3923-6-sw@simonwunderlich.de> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20170316133429.3923-1-sw@simonwunderlich.de> References: <20170316133429.3923-1-sw@simonwunderlich.de> Cc: a@unstable.cc Subject: [B.A.T.M.A.N.] [PATCHv8 5/5] batman-adv: handle race condition for claims between gateways X-BeenThere: b.a.t.m.a.n@lists.open-mesh.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: The list for a Better Approach To Mobile Ad-hoc Networking List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: The list for a Better Approach To Mobile Ad-hoc Networking Errors-To: b.a.t.m.a.n-bounces@lists.open-mesh.org Sender: "B.A.T.M.A.N" From: Andreas Pape Consider the following situation which has been found in a test setup: Gateway B has claimed client C and gateway A has the same backbone network as B. C sends a broad- or multicast to B and directly after this packet decides to send another packet to A due to a better TQ value. B will forward the broad-/multicast into the backbone as it is the responsible gw and after that A will claim C as it has been chosen by C as the best gateway. If it now happens that A claims C before it has received the broad-/multicast forwarded by B (due to backbone topology or due to some delay in B when forwarding the packet) we get a critical situation: in the current code A will immediately unclaim C when receiving the multicast due to the roaming client scenario although the position of C has not changed in the mesh. If this happens the multi-/broadcast forwarded by B will be sent back into the mesh by A and we have looping packets until one of the gateways claims C again. In order to prevent this, unclaiming of a client due to the roaming client scenario is only done after a certain time is expired after the last claim of the client. 100 ms are used here, which should be slow enough for big backbones and slow gateways but fast enough not to break the roaming client use case. Acked-by: Simon Wunderlich Signed-off-by: Andreas Pape [sven@narfation.org: fix conflicts with current version] Signed-off-by: Sven Eckelmann Signed-off-by: Simon Wunderlich --- net/batman-adv/bridge_loop_avoidance.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c index 852a2be1..d07e89ec 100644 --- a/net/batman-adv/bridge_loop_avoidance.c +++ b/net/batman-adv/bridge_loop_avoidance.c @@ -1973,10 +1973,22 @@ bool batadv_bla_tx(struct batadv_priv *bat_priv, struct sk_buff *skb, /* if yes, the client has roamed and we have * to unclaim it. */ - batadv_handle_unclaim(bat_priv, primary_if, - primary_if->net_dev->dev_addr, - ethhdr->h_source, vid); - goto allow; + if (batadv_has_timed_out(claim->lasttime, 100)) { + /* only unclaim if the last claim entry is + * older than 100 ms to make sure we really + * have a roaming client here. + */ + batadv_dbg(BATADV_DBG_BLA, bat_priv, "bla_tx(): Roaming client %pM detected. Unclaim it.\n", + ethhdr->h_source); + batadv_handle_unclaim(bat_priv, primary_if, + primary_if->net_dev->dev_addr, + ethhdr->h_source, vid); + goto allow; + } else { + batadv_dbg(BATADV_DBG_BLA, bat_priv, "bla_tx(): Race for claim %pM detected. Drop packet.\n", + ethhdr->h_source); + goto handled; + } } /* check if it is a multicast/broadcast frame */