From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fout-b2-smtp.messagingengine.com (fout-b2-smtp.messagingengine.com [202.12.124.145]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2AB6122FE08 for ; Sun, 29 Jun 2025 14:49:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=202.12.124.145 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751208582; cv=none; b=WlepudJi8lpdGYeELn4rMSUx9XS9oyXZFek3LhIbutlilLDCQAkIjXb915vAoENwIvJzYgeBLT/1Kq24suRqUTgsJ6Zerg04/8DXvQ4nuS3Am2FUM84Yzahv3n6Fr/UCXtSUutD1M2FKV8E2sBj1mWvoxhmaGisRHfWmYzedvc8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751208582; c=relaxed/simple; bh=BHVC8yjz55Ywp3jBcv+jABdLa4jCYjQuMYq6cS2AZMU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=pRfVpBjay3FeWqnUN7+f8N1q1pVTUG8oEILtGjBEPKrQ0YPBPeWg041R5pNGz8yisWNjgXj0T2kTAxW4bRdfM/6VWa2FvHhYSPQXfz6dwoCP07p4adCIpREeAvRFb4Bi7UMdHIcC+/Xzozw3kPRtVOx8ad9aGJiY4UU1CHZZ72M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=idosch.org; spf=none smtp.mailfrom=idosch.org; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b=HaCM6e9e; arc=none smtp.client-ip=202.12.124.145 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=idosch.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=idosch.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="HaCM6e9e" Received: from phl-compute-05.internal (phl-compute-05.phl.internal [10.202.2.45]) by mailfout.stl.internal (Postfix) with ESMTP id 0E4C01D0019A; Sun, 29 Jun 2025 10:49:40 -0400 (EDT) Received: from phl-mailfrontend-02 ([10.202.2.163]) by phl-compute-05.internal (MEProxy); Sun, 29 Jun 2025 10:49:40 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:subject:subject:to :to:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm2; t= 1751208579; x=1751294979; bh=y1az3t2hQw/fffxwjtVQiWBjYhlRLLVMY7f qHgj+gZ4=; b=HaCM6e9eg63omjlth7ialOPcukK5gA67OmeQrjeLKg6eKbtVoey JZJzEMZed2jeMIMmvlt8xFHbCBRyR06DtwxUSgpC1woIl9cOi+SEtHOJ94dk1LHW gNJpgifcTe9rxfbeOvQmQg28qWIx3cMmlwjBwOVaXSK/LnE08oUoxWK+Va5DhcCy GNqeU4y7uC4yfkqrF8VFX3MMSU3Vw/RNdt2K3WQ0kPb0oE+w7gUxxQ+IyT6jBPX2 8afH29VRU9r3Xy0WmyYQ/6vUm7gN4Eu48eNoK0YF4oxEQVqCxAPhtbqeshVPnJRF pXyoHEUVS4f6sOEcmvUIvvW8bvWbAHD2A5g== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeeffedrtdefgdeludduucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfurfetoffkrfgpnffqhgenuceurghi lhhouhhtmecufedttdenucenucfjughrpeffhffvvefukfhfgggtuggjsehttdertddttd dvnecuhfhrohhmpefkughoucfutghhihhmmhgvlhcuoehiughoshgthhesihguohhstghh rdhorhhgqeenucggtffrrghtthgvrhhnpeehudekfeetieekkeejveehhfdtveegheette ehgfekieeiffegvdekfeeglefggfenucffohhmrghinhepkhgvrhhnvghlrdhorhhgpddu feelrdhithenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhroh hmpehiughoshgthhesihguohhstghhrdhorhhgpdhnsggprhgtphhtthhopeejpdhmohgu vgepshhmthhpohhuthdprhgtphhtthhopehlihhnghesmhhovgguohhvvgdrtghomhdprh gtphhtthhopehgnhgruhhlthesrhgvughhrghtrdgtohhmpdhrtghpthhtohepnhgvthgu vghvsehvghgvrhdrkhgvrhhnvghlrdhorhhgpdhrtghpthhtohepkhhusggrsehkvghrnh gvlhdrohhrghdprhgtphhtthhopehprggsvghnihesrhgvughhrghtrdgtohhmpdhrtghp thhtohepuggrvhgvmhesuggrvhgvmhhlohhfthdrnhgvthdprhgtphhtthhopehnohgtse hmohgvughovhgvrdgtohhm X-ME-Proxy: Feedback-ID: i494840e7:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Sun, 29 Jun 2025 10:49:38 -0400 (EDT) Date: Sun, 29 Jun 2025 17:49:36 +0300 From: Ido Schimmel To: Aiden Yang , gnault@redhat.com Cc: netdev@vger.kernel.org, kuba@kernel.org, pabeni@redhat.com, davem@davemloft.net, MoeDove NOC Subject: Re: [BUG] net: gre: IPv6 link-local multicast is silently dropped (Regression) Message-ID: References: Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: + Guillaume Report is here: https://lore.kernel.org/netdev/CANR=AhRM7YHHXVxJ4DmrTNMeuEOY87K2mLmo9KMed1JMr20p6g@mail.gmail.com/ On Sun, Jun 29, 2025 at 02:40:27PM +0800, Aiden Yang wrote: > This report details a regression in the Linux kernel that prevents > IPv6 link-local all-nodes multicast packets (ff02::1) from being > transmitted over a GRE tunnel. The issue is confirmed to have been > introduced between kernel versions 6.1.0-35-cloud-amd64 (working) and > 6.1.0-37-cloud-amd64 (failing) on Debian 12 (Bookworm). Apparently 6.1.0-35-cloud-amd64 is v6.1.137 and 6.1.0-37-cloud-amd64 is v6.1.140. Probably started with: a51dc9669ff8 gre: Fix again IPv6 link-local address generation. In v6.1.139. It skips creating an IPv6 multicast route for some ipgre devices. Can you try the following diff? diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index ba2ec7c870cc..d0a202d0d93e 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -3537,12 +3537,10 @@ static void addrconf_gre_config(struct net_device *dev) * case). Such devices fall back to add_v4_addrs() instead. */ if (!(dev->type == ARPHRD_IPGRE && *(__be32 *)dev->dev_addr == 0 && - idev->cnf.addr_gen_mode == IN6_ADDR_GEN_MODE_EUI64)) { + idev->cnf.addr_gen_mode == IN6_ADDR_GEN_MODE_EUI64)) addrconf_addr_gen(idev, true); - return; - } - - add_v4_addrs(idev); + else + add_v4_addrs(idev); if (dev->flags & IFF_POINTOPOINT) addrconf_add_mroute(dev); Guillaume, AFAICT, after commit d3623dd5bd4e ("ipv6: Simplify link-local address generation for IPv6 GRE.") in net-next an IPv6 multicast route will be created for every ip6gre device, regardless of IFF_POINTOPOINT. It should restore the behavior before commit e5dd729460ca ("ip/ip6_gre: use the same logic as SIT interfaces when computing v6LL address"). We can extend gre_ipv6_lladdr.sh to test this once the fix is in net-next.