bpf: add map tests for BPF_PROG_TYPE_SK_MSG

Add map tests to attach BPF_PROG_TYPE_SK_MSG types to a sockmap.

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
diff --git a/tools/testing/selftests/bpf/sockmap_parse_prog.c b/tools/testing/selftests/bpf/sockmap_parse_prog.c
index a1dec2b..0f92858 100644
--- a/tools/testing/selftests/bpf/sockmap_parse_prog.c
+++ b/tools/testing/selftests/bpf/sockmap_parse_prog.c
@@ -20,14 +20,25 @@ int bpf_prog1(struct __sk_buff *skb)
 	__u32 lport = skb->local_port;
 	__u32 rport = skb->remote_port;
 	__u8 *d = data;
+	__u32 len = (__u32) data_end - (__u32) data;
+	int err;
 
-	if (data + 10 > data_end)
-		return skb->len;
+	if (data + 10 > data_end) {
+		err = bpf_skb_pull_data(skb, 10);
+		if (err)
+			return SK_DROP;
+
+		data_end = (void *)(long)skb->data_end;
+		data = (void *)(long)skb->data;
+		if (data + 10 > data_end)
+			return SK_DROP;
+	}
 
 	/* This write/read is a bit pointless but tests the verifier and
 	 * strparser handler for read/write pkt data and access into sk
 	 * fields.
 	 */
+	d = data;
 	d[7] = 1;
 	return skb->len;
 }