selftest/bpf: Add test for af_vsock poll()

Verify that vsock's poll() notices when sk_psock::ingress_msg isn't empty.

Signed-off-by: Michal Luczaj <mhal@rbox.co>
Acked-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/r/20241118-vsock-bpf-poll-close-v1-2-f1b9669cacdc@rbox.co
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>

Author: mmhal

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

@@ -937,6 +937,50 @@ static void test_sockmap_same_sock(void)
 	test_sockmap_pass_prog__destroy(skel);
 }
 
+static void test_sockmap_skb_verdict_vsock_poll(void)
+{
+	struct test_sockmap_pass_prog *skel;
+	int err, map, conn, peer;
+	struct bpf_program *prog;
+	struct bpf_link *link;
+	char buf = 'x';
+	int zero = 0;
+
+	skel = test_sockmap_pass_prog__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "open_and_load"))
+		return;
+
+	if (create_pair(AF_VSOCK, SOCK_STREAM, &conn, &peer))
+		goto destroy;
+
+	prog = skel->progs.prog_skb_verdict;
+	map = bpf_map__fd(skel->maps.sock_map_rx);
+	link = bpf_program__attach_sockmap(prog, map);
+	if (!ASSERT_OK_PTR(link, "bpf_program__attach_sockmap"))
+		goto close;
+
+	err = bpf_map_update_elem(map, &zero, &conn, BPF_ANY);
+	if (!ASSERT_OK(err, "bpf_map_update_elem"))
+		goto detach;
+
+	if (xsend(peer, &buf, 1, 0) != 1)
+		goto detach;
+
+	err = poll_read(conn, IO_TIMEOUT_SEC);
+	if (!ASSERT_OK(err, "poll"))
+		goto detach;
+
+	if (xrecv_nonblock(conn, &buf, 1, 0) != 1)
+		FAIL("xrecv_nonblock");
+detach:
+	bpf_link__detach(link);
+close:
+	xclose(conn);
+	xclose(peer);
+destroy:
+	test_sockmap_pass_prog__destroy(skel);
+}
+
 void test_sockmap_basic(void)
 {
 	if (test__start_subtest("sockmap create_update_free"))
@@ -997,4 +1041,6 @@ void test_sockmap_basic(void)
 		test_skmsg_helpers_with_link(BPF_MAP_TYPE_SOCKMAP);
 	if (test__start_subtest("sockhash sk_msg attach sockhash helpers with link"))
 		test_skmsg_helpers_with_link(BPF_MAP_TYPE_SOCKHASH);
+	if (test__start_subtest("sockmap skb_verdict vsock poll"))
+		test_sockmap_skb_verdict_vsock_poll();
 }