Re: [PATCH v3] net: fix wrong network header length
From: Paolo Abeni
Date: Thu Feb 17 2022 - 03:45:38 EST
Hello,
On Thu, 2022-02-17 at 15:01 +0800, Lina Wang wrote:
> On Wed, 2022-02-16 at 19:05 -0800, Alexei Starovoitov wrote:
> > On Tue, Feb 15, 2022 at 11:37 PM Lina Wang <lina.wang@xxxxxxxxxxxx>
> > wrote:
> > >
> > > When clatd starts with ebpf offloaing, and NETIF_F_GRO_FRAGLIST is
> > > enable,
> > > several skbs are gathered in skb_shinfo(skb)->frag_list. The first
> > > skb's
> > > ipv6 header will be changed to ipv4 after bpf_skb_proto_6_to_4,
> > > network_header\transport_header\mac_header have been updated as
> > > ipv4 acts,
> > > but other skbs in frag_list didnot update anything, just ipv6
> > > packets.
> >
> > Please add a test that demonstrates the issue and verifies the fix.
>
> I used iperf udp test to verify the patch, server peer enabled -d to debug
> received packets.
>
> 192.0.0.4 is clatd interface ip, corresponding ipv6 addr is
> 2000:1:1:1:afca:1b1f:1a9:b367, server peer ip is 1.1.1.1,
> whose ipv6 is 2004:1:1:1::101:101.
>
> Without the patch, when udp length 2840 packets received, iperf shows:
> pcount 1 packet_count 0
> pcount 27898727 packet_count 1
> pcount 3 packet_count 27898727
>
> pcount should be 2, but is 27898727(0x1a9b367) , which is 20 bytes put
> forward.
>
> 12:08:02.680299 Unicast to us 2004:1:1:1::101:101 2000:1:1:1:afca:1b1f:1a9:b367 UDP 51196 → 5201 Len=2840
> 0000 20 00 00 01 00 01 00 01 af ca 1b 1f 01 a9 b3 67 ipv6 dst address
> 0000 c7 fc 14 51 0b 20 c7 ab udp header
> 0000 00 00 00 ab 00 0e f3 49 00 00 00 01 08 06 69 d2 00000001 is pcount
> 12:08:02.682084 Unicast to us 1.1.1.1 192.0.0.4 UDP 51196 → 5201 Len=2840
>
> After applied the patch, there is no OOO, pcount acted in order.
To clarify: Alexei is asking to add a test under:
tools/testing/selftests/net/
to cover this specific case. You can propbably extend the existing
udpgro_fwd.sh.
Please explicitly CC people who gave feedback to previous iterations,
it makes easier to track the discussion.
/P