selftests/bpf: Test bpf_sk_storage_get in tcp iterators

/* This creates a socket and its local storage. It then runs a task_iter BPF

 * program that replaces the existing socket local storage with the tgid of the

 * only task owning a file descriptor to this socket, this process, prog_tests.

 * It then runs a tcp socket iterator that negates the value in the existing

 * socket local storage, the test verifies that the resulting value is -pid.

 */

static void test_bpf_sk_storage_get(void)

{

	if (CHECK(sock_fd < 0, "socket", "errno: %d\n", errno))

		goto out;

	err = listen(sock_fd, 1);

	if (CHECK(err != 0, "listen", "errno: %d\n", errno))

		goto close_socket;

	map_fd = bpf_map__fd(skel->maps.sk_stg_map);

	err = bpf_map_update_elem(map_fd, &sock_fd, &val, BPF_NOEXIST);

	do_dummy_read(skel->progs.fill_socket_owner);

	err = bpf_map_lookup_elem(map_fd, &sock_fd, &val);

	CHECK(err || val != getpid(), "bpf_map_lookup_elem",

	if (CHECK(err || val != getpid(), "bpf_map_lookup_elem",

	    "map value wasn't set correctly (expected %d, got %d, err=%d)\n",

	    getpid(), val, err))

		goto close_socket;

	do_dummy_read(skel->progs.negate_socket_local_storage);

	err = bpf_map_lookup_elem(map_fd, &sock_fd, &val);

	CHECK(err || val != -getpid(), "bpf_map_lookup_elem",

	      "map value wasn't set correctly (expected %d, got %d, err=%d)\n",

	      getpid(), val, err);

	      -getpid(), val, err);

close_socket:

	close(sock_fd);

	return 0;

}

SEC("iter/tcp")

int negate_socket_local_storage(struct bpf_iter__tcp *ctx)

{

	struct sock_common *sk_common = ctx->sk_common;

	int *sock_tgid;

	if (!sk_common)

		return 0;

	sock_tgid = bpf_sk_storage_get(&sk_stg_map, sk_common, 0, 0);

	if (!sock_tgid)

		return 0;

	*sock_tgid = -*sock_tgid;

	return 0;

}