ip6_tunnel: set inner ipproto before ip6_tnl_encap

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

Fixes: 6c11fbf97e69 ("ip6_tunnel: add MPLS transmit support")
Signed-off-by: Alexander Ovechkin <ovov@yandex-team.ru>
Link: https://lore.kernel.org/r/20201029171012.20904-1-ovov@yandex-team.ru
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index a0217e5bf3bc1132969e0ed7421cf5eceff54d69..648db3fe508f03f269b9a16bc2340f536ad6bb7c 100644 (file)
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -1271,6 +1271,8 @@ route_lookup:
        if (max_headroom > dev->needed_headroom)
                dev->needed_headroom = max_headroom;
 
+       skb_set_inner_ipproto(skb, proto);
+
        err = ip6_tnl_encap(skb, t, &proto, fl6);
        if (err)
                return err;
@@ -1280,8 +1282,6 @@ route_lookup:
                ipv6_push_frag_opts(skb, &opt.ops, &proto);
        }
 
-       skb_set_inner_ipproto(skb, proto);
-
        skb_push(skb, sizeof(struct ipv6hdr));
        skb_reset_network_header(skb);
        ipv6h = ipv6_hdr(skb);