selftests/bpf: xdp_metadata: Check XDP_REDIRCT support for dev-bound progs

Improve xdp_metadata bpf selftest in order to check it is possible for a
XDP dev-bound program to perform XDP_REDIRECT into a DEVMAP but it is still
not allowed to attach a XDP dev-bound program to a DEVMAP entry.

Signed-off-by: Lorenzo Bianconi <[e-mail]>
Signed-off-by: Martin KaFai Lau <[e-mail]>
Acked-by: Stanislav Fomichev <[e-mail]>

tools/testing/selftests/bpf/prog_tests/xdp_metadata.c

···
 	struct xdp_metadata2 *bpf_obj2 = NULL;
 	struct xdp_metadata *bpf_obj = NULL;
 	struct bpf_program *new_prog, *prog;
+	struct bpf_devmap_val devmap_e = {};
+	struct bpf_map *prog_arr, *devmap;
 	struct nstoken *tok = NULL;
 	__u32 queue_id = QUEUE_ID;
-	struct bpf_map *prog_arr;
 	struct xsk tx_xsk = {};
 	struct xsk rx_xsk = {};
 	__u32 val, key = 0;
···
 	bpf_program__set_ifindex(prog, rx_ifindex);
 	bpf_program__set_flags(prog, BPF_F_XDP_DEV_BOUND_ONLY);
 
+	/* Make sure we can load a dev-bound program that performs
+	 * XDP_REDIRECT into a devmap.
+	 */
+	new_prog = bpf_object__find_program_by_name(bpf_obj->obj, "redirect");
+	bpf_program__set_ifindex(new_prog, rx_ifindex);
+	bpf_program__set_flags(new_prog, BPF_F_XDP_DEV_BOUND_ONLY);
+
 	if (!ASSERT_OK(xdp_metadata__load(bpf_obj), "load skeleton"))
 		goto out;
 
···
 	if (!ASSERT_ERR(bpf_map__update_elem(prog_arr, &key, sizeof(key),
 					     &val, sizeof(val), BPF_ANY),
 			"update prog_arr"))
+		goto out;
+
+	/* Make sure we can't add dev-bound programs to devmaps. */
+	devmap = bpf_object__find_map_by_name(bpf_obj->obj, "dev_map");
+	if (!ASSERT_OK_PTR(devmap, "no dev_map found"))
+		goto out;
+
+	devmap_e.bpf_prog.fd = val;
+	if (!ASSERT_ERR(bpf_map__update_elem(devmap, &key, sizeof(key),
+					     &devmap_e, sizeof(devmap_e),
+					     BPF_ANY),
+			"update dev_map"))
 		goto out;
 
 	/* Attach BPF program to RX interface. */

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

···
 	__type(value, __u32);
 } prog_arr SEC(".maps");
 
+struct {
+	__uint(type, BPF_MAP_TYPE_DEVMAP);
+	__uint(key_size, sizeof(__u32));
+	__uint(value_size, sizeof(struct bpf_devmap_val));
+	__uint(max_entries, 1);
+} dev_map SEC(".maps");
+
 extern int bpf_xdp_metadata_rx_timestamp(const struct xdp_md *ctx,
 					 __u64 *timestamp) __ksym;
 extern int bpf_xdp_metadata_rx_hash(const struct xdp_md *ctx, __u32 *hash,
···
 				     &meta->rx_vlan_tci);
 
 	return bpf_redirect_map(&xsk, ctx->rx_queue_index, XDP_PASS);
+}
+
+SEC("xdp")
+int redirect(struct xdp_md *ctx)
+{
+	return bpf_redirect_map(&dev_map, ctx->rx_queue_index, XDP_PASS);
 }
 
 char _license[] SEC("license") = "GPL";