From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 A952031E826 for ; Tue, 31 Mar 2026 17:09:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774976979; cv=none; b=OfRokaRtnU/6T7bvLxgNnGFcI9JD1StuEgr/9iLlO54BSHLl+J9hArCk6X2e322gTpkPSEqUiwEV2FimvkkNJc49+Xs3D6UQeapyyqJmkVS9RTpAbQSez63F3Ti5EgB2StgzC0cm2pFsW2XGIICe0hvZshm6tKpaNTuU3LYSdAQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774976979; c=relaxed/simple; bh=13kDrlXu8TctjypoyMwOFmcJfVYKWFb+/Ltb0FAz4x8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=aD2pvDjJC47ECt/YOsl8gI4nU0xrbzPTRkWcFb9rxftcmdfGhfoRtzY/aK6y8MT74AsS9JT5PV9ocBMBE89TN59WRn31na9wjVnEUq5DSvrb4jtdfAb1BkX5H2woiMmycYw6l07aGfj5ad429BX/HX0ca5IMPAOpHASOwMKIkZ4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=W4OznO5F; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="W4OznO5F" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E6DFBC19423; Tue, 31 Mar 2026 17:09:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774976979; bh=13kDrlXu8TctjypoyMwOFmcJfVYKWFb+/Ltb0FAz4x8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=W4OznO5FqcS+cdxb8wrWTj+elPmM4gGvZZp+tx1KllAqGe2Ag40xlumAKWFyCFmI1 PAOqDA7jVUOX3wl97Zs94BaMfgyoA1ImF4lCAVn+IytvBcxTsMT3CfFSqW3daUnD5t gz+peokhANTrQpJbxmm5RILQ810gEHIQAc+Hc0GE238NGIEwFfSpddISEGUdiw1oyD CQ9LXzV62xjB103YrXglDsttt8Ymh+HiJVzViiHBJcaWRMXwWfxPxRl1QJnrA2xYMR N7kUytlh/yVfk/vxJ6oFldmYW3tip6wX2R7KkB283SN6YAJDRvt71ZMKYFjomYsWD4 c8SXPKv0p6bUQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Willem de Bruijn , Tangxin Xie , Paolo Abeni , Sasha Levin Subject: [PATCH 6.12.y] net: correctly handle tunneled traffic on IPV6_CSUM GSO fallback Date: Tue, 31 Mar 2026 13:09:35 -0400 Message-ID: <20260331170935.2813592-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026033030-estate-couch-53d1@gregkh> References: <2026033030-estate-couch-53d1@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Willem de Bruijn [ Upstream commit c4336a07eb6b2526dc2b62928b5104b41a7f81f5 ] NETIF_F_IPV6_CSUM only advertises support for checksum offload of packets without IPv6 extension headers. Packets with extension headers must fall back onto software checksumming. Since TSO depends on checksum offload, those must revert to GSO. The below commit introduces that fallback. It always checks network header length. For tunneled packets, the inner header length must be checked instead. Extend the check accordingly. A special case is tunneled packets without inner IP protocol. Such as RFC 6951 SCTP in UDP. Those are not standard IPv6 followed by transport header either, so also must revert to the software GSO path. Cc: stable@vger.kernel.org Fixes: 864e3396976e ("net: gso: Forbid IPv6 TSO with extensions on devices with only IPV6_CSUM") Reported-by: Tangxin Xie Closes: https://lore.kernel.org/netdev/0414e7e2-9a1c-4d7c-a99d-b9039cf68f40@yeah.net/ Suggested-by: Paolo Abeni Signed-off-by: Willem de Bruijn Link: https://patch.msgid.link/20260320190148.2409107-1-willemdebruijn.kernel@gmail.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- net/core/dev.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index 336257b515f04..eba7a4a39a4cb 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -3579,6 +3579,22 @@ static netdev_features_t dflt_features_check(struct sk_buff *skb, return vlan_features_check(skb, features); } +static bool skb_gso_has_extension_hdr(const struct sk_buff *skb) +{ + if (!skb->encapsulation) + return ((skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6 || + (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4 && + vlan_get_protocol(skb) == htons(ETH_P_IPV6))) && + skb_transport_header_was_set(skb) && + skb_network_header_len(skb) != sizeof(struct ipv6hdr)); + else + return (!skb_inner_network_header_was_set(skb) || + ((skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6 || + (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4 && + inner_ip_hdr(skb)->version == 6)) && + skb_inner_network_header_len(skb) != sizeof(struct ipv6hdr))); +} + static netdev_features_t gso_features_check(const struct sk_buff *skb, struct net_device *dev, netdev_features_t features) @@ -3620,11 +3636,7 @@ static netdev_features_t gso_features_check(const struct sk_buff *skb, * so neither does TSO that depends on it. */ if (features & NETIF_F_IPV6_CSUM && - (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6 || - (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4 && - vlan_get_protocol(skb) == htons(ETH_P_IPV6))) && - skb_transport_header_was_set(skb) && - skb_network_header_len(skb) != sizeof(struct ipv6hdr) && + skb_gso_has_extension_hdr(skb) && !ipv6_has_hopopt_jumbo(skb)) features &= ~(NETIF_F_IPV6_CSUM | NETIF_F_TSO6 | NETIF_F_GSO_UDP_L4); -- 2.53.0