[PATCH 5.9 037/133] ip6_tunnel: set inner ipproto before ip6_tnl_encap

[Greg Kroah-Hartman]

From: Alexander Ovechkin <ovov@xxxxxxxxxxxxxx>

[ Upstream commit 9e7c5b396e98eed859d3dd1ab235912a296faab5 ]

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@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20201029171012.20904-1-ovov@xxxxxxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/ipv6/ip6_tunnel.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- 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);