netdev - Re: [PATCH net-next v3 1/3] tc: adjust network header after 2nd vlan push

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Message-ID: <ZscNRU9a8DWBQ67K@ramen>
Date: Thu, 22 Aug 2024 13:04:53 +0300
From: Boris Sukholitko <boris.sukholitko@...adcom.com>
To: Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, Martin KaFai Lau <martin.lau@...ux.dev>,
	Daniel Borkmann <daniel@...earbox.net>,
	John Fastabend <john.fastabend@...il.com>,
	Alexei Starovoitov <ast@...nel.org>,
	Andrii Nakryiko <andrii@...nel.org>,
	Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>,
	Yonghong Song <yonghong.song@...ux.dev>,
	KP Singh <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>,
	Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
	"David S . Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Pravin B Shelar <pshelar@....org>,
	Jamal Hadi Salim <jhs@...atatu.com>,
	Cong Wang <xiyou.wangcong@...il.com>, Jiri Pirko <jiri@...nulli.us>,
	Shuah Khan <shuah@...nel.org>,
	Willem de Bruijn <willemb@...gle.com>,
	Pavel Begunkov <asml.silence@...il.com>,
	Mina Almasry <almasrymina@...gle.com>,
	Lorenzo Bianconi <lorenzo@...nel.org>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	David Howells <dhowells@...hat.com>,
	Liang Chen <liangchen.linux@...il.com>,
	Alexander Lobakin <aleksander.lobakin@...el.com>,
	Thomas Weißschuh <linux@...ssschuh.net>,
	Ido Schimmel <idosch@...sch.org>,
	Ilya Lifshits <ilya.lifshits@...adcom.com>
Subject: Re: [PATCH net-next v3 1/3] tc: adjust network header after 2nd vlan
 push

On Thu, Aug 22, 2024 at 11:41:19AM +0200, Paolo Abeni wrote:
> On 8/19/24 13:06, Boris Sukholitko wrote:
> > diff --git a/net/sched/act_vlan.c b/net/sched/act_vlan.c
> > index 22f4b1e8ade9..9e2dbde3cc29 100644
> > --- a/net/sched/act_vlan.c
> > +++ b/net/sched/act_vlan.c
> > @@ -96,6 +96,7 @@ TC_INDIRECT_SCOPE int tcf_vlan_act(struct sk_buff *skb,
> >   	if (skb_at_tc_ingress(skb))
> >   		skb_pull_rcsum(skb, skb->mac_len);
> > +	skb_reset_mac_header(skb);
> 
> This should be:
> 	 skb_reset_mac_len(skb);
> right?

Right. Good catch, sorry. I'll send v4 with the fix shortly.

> 
> I'm baffled by the fact that the self-tests looks still happy?!?
> 

My guess is that the TC code path doesn't look at the faulty skb->mac_len.
At least the dissector doesn't.

Thanks,
Boris.

> Thanks,
> 
> Paolo
>