From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-184.mta0.migadu.com (out-184.mta0.migadu.com [91.218.175.184]) (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 59D2D3D7A10 for ; Mon, 1 Jun 2026 15:03:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.184 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780326183; cv=none; b=jtDW4Ig6IX/Mdg0jn9Uegn8+N93jEH93xbdatQ2XyB1jSSjT9XB6b0CJVBcxu7eRhiZkMQqCH7YbzH7U00e+oduN/rxakVrNtdhprGcrwrpsxKTJfG3qll1kVSv+sOwycaSe9gpn134f6FmWinmOSgXZrnoeEVfvq4aX6m9rKT4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780326183; c=relaxed/simple; bh=2n8VPR+adUItluq7skj6quLn2kXUdgZ2t/EMyoe1Cnw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=QgkLqIwAn+RMZ8m63KlpS2Gv5DEr0b1pCJta8h0WNtbRUIMyyJfSZTk9kqqxIpl6HD5468rGyUiiaridugfJqu9dtu91Zfn1egoWK/K6ZYmQFhlxqk2kaQ9jSZonT653MbqW58ucT2vCIfojh9kPKt7YOwx9sYyFqiEuDJ+E/Qw= 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=Y6jAYJ0l; arc=none smtp.client-ip=91.218.175.184 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="Y6jAYJ0l" 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=1780326175; 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=zCSA/PBONDUBP5eeEykp2x6KTzS6ipF0VTJLK4oCWt8=; b=Y6jAYJ0lV4ZRrwDE3SINAIwYuH0BzJ8gaMw60DW0t7SNRqR/zQltEXuMQS33RkDdU5EMkN Ml9zKLqnuMyq/99GoemZ4aEhHPll4VggLbxu9mw0kDT2a9ogQbEM1oqVU4ZXgKLBsWqDsu irxy5k6U2gxLCpZMXQt774PjuRduAKI= 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 v3 1/2] bpf: Update transport_header when encapsulating UDP tunnel in lwt Date: Mon, 1 Jun 2026 23:02:02 +0800 Message-ID: <20260601150203.20352-2-leon.hwang@linux.dev> In-Reply-To: <20260601150203.20352-1-leon.hwang@linux.dev> References: <20260601150203.20352-1-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 f71ef82a5f3d..65d1dfbf3312 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 +644,10 @@ 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 (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)); memcpy(skb_network_header(skb), hdr, len); bpf_compute_data_pointers(skb); skb_clear_hash(skb); -- 2.54.0