selftests/bpf: convert bpf tunnel test to encap modes

Make the tests correctly annotate skbs with tunnel metadata.

This makes the gso tests succeed. Enable them.
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/progs/test_tc_tunnel.c

@@ -70,8 +70,13 @@ static __always_inline int encap_ipv4(struct __sk_buff *skb, bool with_gre)
 	if (tcph.dest != __bpf_constant_htons(cfg_port))
 		return TC_ACT_OK;
 
-	flags = BPF_F_ADJ_ROOM_FIXED_GSO;
-	olen = with_gre ? sizeof(h_outer) : sizeof(h_outer.ip);
+	flags = BPF_F_ADJ_ROOM_FIXED_GSO | BPF_F_ADJ_ROOM_ENCAP_L3_IPV4;
+	if (with_gre) {
+		flags |= BPF_F_ADJ_ROOM_ENCAP_L4_GRE;
+		olen = sizeof(h_outer);
+	} else {
+		olen = sizeof(h_outer.ip);
+	}
 
 	/* add room between mac and network header */
 	if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_MAC, flags))
@@ -119,8 +124,14 @@ static __always_inline int encap_ipv6(struct __sk_buff *skb, bool with_gre)
 	if (tcph.dest != __bpf_constant_htons(cfg_port))
 		return TC_ACT_OK;
 
-	flags = BPF_F_ADJ_ROOM_FIXED_GSO;
-	olen = with_gre ? sizeof(h_outer) : sizeof(h_outer.ip);
+	flags = BPF_F_ADJ_ROOM_FIXED_GSO | BPF_F_ADJ_ROOM_ENCAP_L3_IPV6;
+	if (with_gre) {
+		flags |= BPF_F_ADJ_ROOM_ENCAP_L4_GRE;
+		olen = sizeof(h_outer);
+	} else {
+		olen = sizeof(h_outer.ip);
+	}
+
 
 	/* add room between mac and network header */
 	if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_MAC, flags))

tools/testing/selftests/bpf/test_tc_tunnel.sh

@@ -97,13 +97,11 @@ if [[ "$#" -eq "0" ]]; then
 	echo "ip6 gre"
 	$0 ipv6 ip6gre 100
 
-	# disabled until passes SKB_GSO_DODGY checks
-	# echo "ip gre gso"
-	# $0 ipv4 gre 2000
+	echo "ip gre gso"
+	$0 ipv4 gre 2000
 
-	# disabled until passes SKB_GSO_DODGY checks
-	# echo "ip6 gre gso"
-	# $0 ipv6 ip6gre 2000
+	echo "ip6 gre gso"
+	$0 ipv6 ip6gre 2000
 
 	echo "OK. All tests passed"
 	exit 0