From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-180.mta1.migadu.com (out-180.mta1.migadu.com [95.215.58.180]) (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 B1B0C3CF04F for ; Tue, 2 Jun 2026 15:10:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.180 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780413011; cv=none; b=JRTmyCGfocDvteqn5l/aO8jYriMDXCEe1qw1yZ/sMAnATJ0n8YxIEEBBgGdYRM6gFwnCzVfYKVve4hFvBTNZNCVBQTnA5ZoqVexPnc2J6w2yOoHmOOhnOfL+WHgzG2hqoOK5Bb9amltmUBb/d9vL81xJxI/JO57dZgLvpCfCho0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780413011; c=relaxed/simple; bh=DXp2X70flAXfG/kzP8CdrTOeSuh4Viz320NCs6owwFI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=EZDSO1JktWQ6vO5vmm1wRDvdCf1tCemWgwsHbTNzljjt9TkvdtEX5Wy4eeK7yfvCJOzlSA37eRJ8HRqtmTGBvQBTWhRXMJd7S2I9KydFfOCyoWWcfn7bzyLQI6e5pLbU11Ld3qgb5cZR+BITSQuyxgy89bIHwx38Hhep8qbyXu4= 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=p+INKBX0; arc=none smtp.client-ip=95.215.58.180 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="p+INKBX0" 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=1780413008; 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=t6+rTtBYw3wQtorJ+PDFHLzmGteg47Xmh+985+kjaOo=; b=p+INKBX0/O7gwKDM+gqG7sz2bBKHwqacmIXloXhTr1PqC1uMcZIuQeUuTKAoAR6j7j519N CMzYtZV/JFYUBAbx9Y6VlVAYlcVqyIZHhNK4njhHJcjfR8uNIAG3w1TzIN8JYxs2yZrBYZ cHxJwBTLgCOi06TeBFLi7+p/OQu0/98= 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 v4 1/2] bpf: Update transport_header when encapsulating UDP tunnel in lwt Date: Tue, 2 Jun 2026 23:09:30 +0800 Message-ID: <20260602150931.49629-2-leon.hwang@linux.dev> In-Reply-To: <20260602150931.49629-1-leon.hwang@linux.dev> References: <20260602150931.49629-1-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 | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/net/core/lwt_bpf.c b/net/core/lwt_bpf.c index f71ef82a5f3d..bf588f508b79 100644 --- a/net/core/lwt_bpf.c +++ b/net/core/lwt_bpf.c @@ -599,6 +599,7 @@ 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) { + bool is_udp_tunnel; struct iphdr *iph; bool ipv4; int err; @@ -612,10 +613,16 @@ int bpf_lwt_push_ip_encap(struct sk_buff *skb, void *hdr, u32 len, bool ingress) ipv4 = true; if (unlikely(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; } @@ -637,6 +644,11 @@ int bpf_lwt_push_ip_encap(struct sk_buff *skb, void *hdr, u32 len, bool ingress) if (ingress) skb_postpush_rcsum(skb, iph, len); skb_reset_network_header(skb); + if (is_udp_tunnel) { + size_t iph_sz = ipv4 ? iph->ihl * 4 : sizeof(struct ipv6hdr); + + skb_set_transport_header(skb, skb_network_offset(skb) + iph_sz); + } memcpy(skb_network_header(skb), hdr, len); bpf_compute_data_pointers(skb); skb_clear_hash(skb); -- 2.54.0