From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-188.mta1.migadu.com (out-188.mta1.migadu.com [95.215.58.188]) (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 6DFA5373BE9; Tue, 2 Jun 2026 03:17:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.188 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780370256; cv=none; b=F747bSH2aKHDr3aXQdRT13r7qLsXo8NJjXwZlB3diF79E1zf0yRuqCcCobxTKc+Pdbh2GjHay9wEHfFsL/igxQ6ilAzkkZ1YZsHgobbSa0pdcVD0NDL/h8tvzm3NzDJnPM0fiwxAjE6nvwJ5vKUvWj2PRrj78VylInPuYOqOmkA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780370256; c=relaxed/simple; bh=gvgIJo9m/HUHg9gk2qU3NCinlFuIOES/GGZ227Us+6Q=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Mc0h1QgGHMYbDQg47WDkKfU3tRL8xBfDM0msJ+m2S/Jn0kgnL/jDoWBPvjIFSOszhfs8h94zWKztqFkwqi+gjU786gkDxhLG7P7gSMx/Ea1m7NXyKXiy4YVaz6dkghAz3rVLHwfVUX80ToSTUiZBigAo2y7AiqewjyBs92agegg= 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=WHV8r6eo; arc=none smtp.client-ip=95.215.58.188 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="WHV8r6eo" Message-ID: <0fecd90a-d218-48dc-86d1-860ab2e7f6d5@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1780370252; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Q31l8Uyd8/waps4/zvDwbRE+yDFblOOOVBggVCClT4g=; b=WHV8r6eoERREXxCCRWjY2eCmtSkAlgARpuzh0h1dndgYom86wLyWawWBQ0ihkvMvPM7O8Y 5cVT0y3iBdevFuRq4D8aCpnspn3R8dARNJRC1RJ2IlsEfPrjyK1U0LLqP9omm4Gs+xoJYg ANKtSjCbOfW8avUq3gZ/XtK1pfIwO+A= Date: Tue, 2 Jun 2026 11:17:15 +0800 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH bpf v3 1/2] bpf: Update transport_header when encapsulating UDP tunnel in lwt To: Leon Hwang , 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 , 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 References: <20260601150203.20352-1-leon.hwang@linux.dev> <20260601150203.20352-2-leon.hwang@linux.dev> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Jiayuan Chen In-Reply-To: <20260601150203.20352-2-leon.hwang@linux.dev> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 6/1/26 11:02 PM, Leon Hwang wrote: > 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)); I think GRE is also affected, why not unconditionally set transport header to network_offset + outer_ip_ihl regardless of outer protocol?? > memcpy(skb_network_header(skb), hdr, len); > bpf_compute_data_pointers(skb); > skb_clear_hash(skb);