From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760745Ab3GZVoq (ORCPT ); Fri, 26 Jul 2013 17:44:46 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:50727 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759826Ab3GZUsQ (ORCPT ); Fri, 26 Jul 2013 16:48:16 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Pierre Emeriaud , YOSHIFUJI Hideaki , Hannes Frederic Sowa , "David S. Miller" Subject: [ 15/79] ipv6: rt6_check_neigh should successfully verify neigh if no NUD information are available Date: Fri, 26 Jul 2013 13:47:05 -0700 Message-Id: <20130726204723.522556889@linuxfoundation.org> X-Mailer: git-send-email 1.8.3.rc0.20.gb99dd2e In-Reply-To: <20130726204721.849052763@linuxfoundation.org> References: <20130726204721.849052763@linuxfoundation.org> User-Agent: quilt/0.60-5.1.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Hannes Frederic Sowa [ Upstream commit 3630d40067a21d4dfbadc6002bb469ce26ac5d52 ] After the removal of rt->n we do not create a neighbour entry at route insertion time (rt6_bind_neighbour is gone). As long as no neighbour is created because of "useful traffic" we skip this routing entry because rt6_check_neigh cannot pick up a valid neighbour (neigh == NULL) and thus returns false. This change was introduced by commit 887c95cc1da53f66a5890fdeab13414613010097 ("ipv6: Complete neighbour entry removal from dst_entry.") To quote RFC4191: "If the host has no information about the router's reachability, then the host assumes the router is reachable." and also: "A host MUST NOT probe a router's reachability in the absence of useful traffic that the host would have sent to the router if it were reachable." So, just assume the router is reachable and let's rt6_probe do the rest. We don't need to create a neighbour on route insertion time. If we don't compile with CONFIG_IPV6_ROUTER_PREF (RFC4191 support) a neighbour is only valid if its nud_state is NUD_VALID. I did not find any references that we should probe the router on route insertion time via the other RFCs. So skip this route in that case. v2: a) use IS_ENABLED instead of #ifdefs (thanks to Sergei Shtylyov) Reported-by: Pierre Emeriaud Cc: YOSHIFUJI Hideaki Signed-off-by: Hannes Frederic Sowa Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv6/route.c | 2 ++ 1 file changed, 2 insertions(+) --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -547,6 +547,8 @@ static inline bool rt6_check_neigh(struc ret = true; #endif read_unlock(&neigh->lock); + } else if (IS_ENABLED(CONFIG_IPV6_ROUTER_PREF)) { + ret = true; } rcu_read_unlock_bh();