From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-172.mta1.migadu.com (out-172.mta1.migadu.com [95.215.58.172]) (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 5C8B21607A4; Fri, 29 May 2026 15:15:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780067711; cv=none; b=hQ+7NAJBb6wY7aXxHFIcdhesy/BzA3KaUP3aWYKbE1yWdLICREvmtzw6x24Lx25rloqk6ZqLFclXeF2eQtr26DGOa6bNbFQ/1NUbg6pkeBoBk5S+dTXHdj2V82bbBlDwGn0Dw5ZJrZbGbIbGRPWnyLTPbaw9+y9OU4Oj8tu3ZrA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780067711; c=relaxed/simple; bh=SKAT7hw/8Orv13PHCSnTgIBz2Ipz4cxEP3jGinHwIm4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=cdELZBN8DO7onfOCcfQLP3M1zH2DdH+T2P1rGvTHH6/YmuImiF5CdVPgmodAbULdDKVnHQPqE4eqw1ORBM90+Vv5X10RGvS6ITyYIkLzJEnwrHoSgwO5wYWzZj02IljBf5VtKYa7u/yb/oA9fe6a7mJI/hAG4k/T1h80KBhVzDk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=Yf7aKi3K; arc=none smtp.client-ip=95.215.58.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="Yf7aKi3K" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1780067708; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=BNYctVoQYshrW+FHoERDUeT3GUi8gIpDSH2odCxQVMM=; b=Yf7aKi3K+7XdNVq/QbZlpU2cDoF8mDqYwrJlXFI2qk54YQPT0RTJ0nWeDP+/wvdTMYTBr6 PKYmV062GNM1PDVt0YGBTv0VXUvnTpa0UH5j5Os6RIM08zKsNxCm9DGpa2mla4I0ESnT1Y kGQmIgto4txNLwJrXUK8jFYOBWTfpsA= From: Leon Hwang To: bpf@vger.kernel.org Cc: "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Andrii Nakryiko , Eduard Zingerman , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Kumar Kartikeya Dwivedi , Song Liu , Yonghong Song , Jiri Olsa , Shuah Khan , Guillaume Nault , Leon Hwang , Ido Schimmel , Fernando Fernandez Mancera , Peter Oskolkov , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-kselftest@vger.kernel.org, kernel-patches-bot@fb.com, Leon Hwang Subject: [PATCH bpf v2 3/4] bpf: Update transport_header when encapsulating UDP tunnel in lwt Date: Fri, 29 May 2026 23:13:50 +0800 Message-ID: <20260529151351.69911-4-leon.hwang@linux.dev> In-Reply-To: <20260529151351.69911-1-leon.hwang@linux.dev> References: <20260529151351.69911-1-leon.hwang@linux.dev> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT Currently, bpf_lwt_push_ip_encap() does not update skb->transport_header. When a driver, e.g. ice, reuses the stale skb->transport_header to offload checksum computation to NIC hardware, VxLAN packets encapsulated by bpf_lwt_push_encap() helper may be dropped due to incorrect checksum. Update skb->transport_header in bpf_lwt_push_ip_encap() whenever the encapsulated packet uses UDP, so checksum offload works correctly. Fixes: 52f278774e79 ("bpf: implement BPF_LWT_ENCAP_IP mode in bpf_lwt_push_encap") Cc: Leon Hwang Signed-off-by: Leon Hwang --- net/core/lwt_bpf.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/net/core/lwt_bpf.c b/net/core/lwt_bpf.c index c306120e11d2..1d556dec94b4 100644 --- a/net/core/lwt_bpf.c +++ b/net/core/lwt_bpf.c @@ -600,6 +600,7 @@ static int handle_gso_encap(struct sk_buff *skb, bool ipv4, int encap_len) int bpf_lwt_push_ip_encap(struct sk_buff *skb, void *hdr, u32 len, bool ingress) { u8 buff[LWT_BPF_MAX_HEADROOM]; + bool is_udp_tunnel; struct iphdr *iph; bool ipv4; int err; @@ -615,10 +616,16 @@ int bpf_lwt_push_ip_encap(struct sk_buff *skb, void *hdr, u32 len, bool ingress) ipv4 = true; if (unlikely(iph->ihl < 5 || len < iph->ihl * 4)) return -EINVAL; + is_udp_tunnel = iph->protocol == IPPROTO_UDP; + if (unlikely(is_udp_tunnel && len < iph->ihl * 4 + sizeof(struct udphdr))) + return -EINVAL; } else if (iph->version == 6) { ipv4 = false; if (unlikely(len < sizeof(struct ipv6hdr))) return -EINVAL; + is_udp_tunnel = ((struct ipv6hdr *)iph)->nexthdr == NEXTHDR_UDP; + if (unlikely(is_udp_tunnel && len < sizeof(struct ipv6hdr) + sizeof(struct udphdr))) + return -EINVAL; } else { return -EINVAL; } @@ -641,6 +648,10 @@ int bpf_lwt_push_ip_encap(struct sk_buff *skb, void *hdr, u32 len, bool ingress) skb_postpush_rcsum(skb, iph, len); skb_reset_network_header(skb); memcpy(skb_network_header(skb), buff, len); + if (ipv4 && is_udp_tunnel) + skb_set_transport_header(skb, skb_network_offset(skb) + iph->ihl * 4); + else if (!ipv4 && is_udp_tunnel) + skb_set_transport_header(skb, skb_network_offset(skb) + sizeof(struct ipv6hdr)); bpf_compute_data_pointers(skb); skb_clear_hash(skb); -- 2.54.0