From: Vadim Fedorenko <vfedorenko@novek.ru>
To: Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
Alexander Ovechkin <ovov@yandex-team.ru>
Cc: Network Development <netdev@vger.kernel.org>
Subject: Re: [PATCH net] ip6_tunnel: set inner ipproto before ip6_tnl_encap.
Date: Sat, 17 Oct 2020 01:59:31 +0100 [thread overview]
Message-ID: <22adf1a4-9b8d-0502-a677-a812490e0f63@novek.ru> (raw)
In-Reply-To: <CA+FuTSe5szAPV0qDVU1Qa7e-XH6uO4eWELfzykOvpb0CJ0NbUA@mail.gmail.com>
On 16.10.2020 18:55, Willem de Bruijn wrote:
> On Fri, Oct 16, 2020 at 7:14 AM Alexander Ovechkin <ovov@yandex-team.ru> wrote:
>> ip6_tnl_encap assigns to proto transport protocol which
>> encapsulates inner packet, but we must pass to set_inner_ipproto
>> protocol of that inner packet.
>>
>> Calling set_inner_ipproto after ip6_tnl_encap might break gso.
>> For example, in case of encapsulating ipv6 packet in fou6 packet, inner_ipproto
>> would be set to IPPROTO_UDP instead of IPPROTO_IPV6. This would lead to
>> incorrect calling sequence of gso functions:
>> ipv6_gso_segment -> udp6_ufo_fragment -> skb_udp_tunnel_segment -> udp6_ufo_fragment
>> instead of:
>> ipv6_gso_segment -> udp6_ufo_fragment -> skb_udp_tunnel_segment -> ip6ip6_gso_segment
>>
>> Signed-off-by: Alexander Ovechkin <ovov@yandex-team.ru>
> Commit 6c11fbf97e69 ("ip6_tunnel: add MPLS transmit support") moved
> the call from ip6_tnl_encap's caller to inside ip6_tnl_encap.
>
> It makes sense that that likely broke this behavior for UDP (L4) tunnels.
>
> But it was moved on purpose to avoid setting the inner protocol to
> IPPROTO_MPLS. That needs to use skb->inner_protocol to further
> segment.
>
> I suspect we need to set this before or after conditionally to avoid
> breaking that use case.
I hope it could be fixed with something like this:
diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index a0217e5..87368b0 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -1121,6 +1121,7 @@ int ip6_tnl_xmit(struct sk_buff *skb, struct net_device
*dev, __u8 dsfield,
bool use_cache = false;
u8 hop_limit;
int err = -1;
+ __u8 pproto = proto;
if (t->parms.collect_md) {
hop_limit = skb_tunnel_info(skb)->key.ttl;
@@ -1280,7 +1281,7 @@ int ip6_tnl_xmit(struct sk_buff *skb, struct net_device
*dev, __u8 dsfield,
ipv6_push_frag_opts(skb, &opt.ops, &proto);
}
- skb_set_inner_ipproto(skb, proto);
+ skb_set_inner_ipproto(skb, pproto == IPPROTO_MPLS ? proto : pproto);
skb_push(skb, sizeof(struct ipv6hdr));
skb_reset_network_header(skb);
next prev parent reply other threads:[~2020-10-17 6:56 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-16 11:11 [PATCH net] ip6_tunnel: set inner ipproto before ip6_tnl_encap Alexander Ovechkin
2020-10-16 17:55 ` Willem de Bruijn
2020-10-17 0:59 ` Vadim Fedorenko [this message]
2020-10-27 21:45 ` Alexander Ovechkin
2020-10-27 21:44 ` Alexander Ovechkin
2020-10-28 1:53 ` Willem de Bruijn
2020-10-29 4:23 ` Alexander Ovechkin
2020-10-29 14:40 ` Willem de Bruijn
2020-10-29 15:50 ` Vadim Fedorenko
2020-10-30 11:01 ` Vadim Fedorenko
2020-10-30 12:54 ` Alexander Ovechkin
2020-10-31 1:57 ` Vadim Fedorenko
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