static int attach_child_main(void* data)
{
	struct attach_clone_payload* payload = (struct attach_clone_payload*)data;
	int ipc_socket = payload->ipc_socket;
	lxc_attach_options_t* options = payload->options;
	struct lxc_proc_context_info* init_ctx = payload->init_ctx;
#if HAVE_SYS_PERSONALITY_H
	long new_personality;
#endif
	int ret;
	int status;
	int expected;
	long flags;
	int fd;
	int lsm_labelfd;
	uid_t new_uid;
	gid_t new_gid;

	/* wait for the initial thread to signal us that it's ready
	 * for us to start initializing
	 */
	expected = 0;
	status = -1;
	ret = lxc_read_nointr_expect(ipc_socket, &status, sizeof(status), &expected);
	if (ret <= 0) {
		ERROR("Error using IPC to receive notification from initial process (0): %s.", strerror(errno));
		shutdown(ipc_socket, SHUT_RDWR);
		rexit(-1);
	}

	/* A description of the purpose of this functionality is
	 * provided in the lxc-attach(1) manual page. We have to
	 * remount here and not in the parent process, otherwise
	 * /proc may not properly reflect the new pid namespace.
	 */
	if (!(options->namespaces & CLONE_NEWNS) && (options->attach_flags & LXC_ATTACH_REMOUNT_PROC_SYS)) {
		ret = lxc_attach_remount_sys_proc();
		if (ret < 0) {
			shutdown(ipc_socket, SHUT_RDWR);
			rexit(-1);
		}
	}

	/* now perform additional attachments*/
#if HAVE_SYS_PERSONALITY_H
	if (options->personality < 0)
		new_personality = init_ctx->personality;
	else
		new_personality = options->personality;

	if (options->attach_flags & LXC_ATTACH_SET_PERSONALITY) {
		ret = personality(new_personality);
		if (ret < 0) {
			SYSERROR("could not ensure correct architecture");
			shutdown(ipc_socket, SHUT_RDWR);
			rexit(-1);
		}
	}
#endif

	if (options->attach_flags & LXC_ATTACH_DROP_CAPABILITIES) {
		ret = lxc_attach_drop_privs(init_ctx);
		if (ret < 0) {
			ERROR("could not drop privileges");
			shutdown(ipc_socket, SHUT_RDWR);
			rexit(-1);
		}
	}

	/* always set the environment (specify (LXC_ATTACH_KEEP_ENV, NULL, NULL) if you want this to be a no-op) */
	ret = lxc_attach_set_environment(options->env_policy, options->extra_env_vars, options->extra_keep_env);
	if (ret < 0) {
		ERROR("could not set initial environment for attached process");
		shutdown(ipc_socket, SHUT_RDWR);
		rexit(-1);
	}

	/* set user / group id */
	new_uid = 0;
	new_gid = 0;
	/* ignore errors, we will fall back to root in that case
	 * (/proc was not mounted etc.)
	 */
	if (options->namespaces & CLONE_NEWUSER)
		lxc_attach_get_init_uidgid(&new_uid, &new_gid);

	if (options->uid != (uid_t)-1)
		new_uid = options->uid;
	if (options->gid != (gid_t)-1)
		new_gid = options->gid;

	/* setup the control tty */
	if (options->stdin_fd && isatty(options->stdin_fd)) {
		if (setsid() < 0) {
			SYSERROR("unable to setsid");
			shutdown(ipc_socket, SHUT_RDWR);
			rexit(-1);
		}

		if (ioctl(options->stdin_fd, TIOCSCTTY, (char *)NULL) < 0) {
			SYSERROR("unable to TIOCSTTY");
			shutdown(ipc_socket, SHUT_RDWR);
			rexit(-1);
		}
	}

	/* try to set the uid/gid combination */
	if ((new_gid != 0 || options->namespaces & CLONE_NEWUSER)) {
		if (setgid(new_gid) || setgroups(0, NULL)) {
			SYSERROR("switching to container gid");
			shutdown(ipc_socket, SHUT_RDWR);
			rexit(-1);
		}
	}
	if ((new_uid != 0 || options->namespaces & CLONE_NEWUSER) && setuid(new_uid)) {
		SYSERROR("switching to container uid");
		shutdown(ipc_socket, SHUT_RDWR);
		rexit(-1);
	}

	/* tell initial process it may now put us into the cgroups */
	status = 1;
	ret = lxc_write_nointr(ipc_socket, &status, sizeof(status));
	if (ret != sizeof(status)) {
		ERROR("Error using IPC to notify initial process for initialization (1): %s.", strerror(errno));
		shutdown(ipc_socket, SHUT_RDWR);
		rexit(-1);
	}

	/* wait for the initial thread to signal us that it has done
	 * everything for us when it comes to cgroups etc.
	 */
	expected = 2;
	status = -1;
	ret = lxc_read_nointr_expect(ipc_socket, &status, sizeof(status), &expected);
	if (ret <= 0) {
		ERROR("Error using IPC to receive message from initial process "
		      "that it is done pre-initializing (2): %s",
		      strerror(errno));
		shutdown(ipc_socket, SHUT_RDWR);
		rexit(-1);
	}

	if ((init_ctx->container && init_ctx->container->lxc_conf &&
	     init_ctx->container->lxc_conf->no_new_privs) ||
	    (options->attach_flags & LXC_ATTACH_NO_NEW_PRIVS)) {
		if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) < 0) {
			SYSERROR("PR_SET_NO_NEW_PRIVS could not be set. "
				 "Process can use execve() gainable "
				 "privileges.");
			shutdown(ipc_socket, SHUT_RDWR);
			rexit(-1);
		}
		INFO("PR_SET_NO_NEW_PRIVS is set. Process cannot use execve() "
		     "gainable privileges.");
	}

	/* Tell the (grand)parent to send us LSM label fd. */
	status = 3;
	ret = lxc_write_nointr(ipc_socket, &status, sizeof(status));
	if (ret <= 0) {
		ERROR("Error using IPC to tell parent to set up LSM labels (3): %s.", strerror(errno));
		shutdown(ipc_socket, SHUT_RDWR);
		rexit(-1);
	}

	if ((options->namespaces & CLONE_NEWNS) && (options->attach_flags & LXC_ATTACH_LSM) && init_ctx->lsm_label) {
		int on_exec;
		/* Receive fd for LSM security module. */
		ret = lxc_abstract_unix_recv_fd(ipc_socket, &lsm_labelfd, NULL, 0);
		if (ret <= 0) {
			ERROR("Error using IPC for parent to tell us LSM label fd (4): %s.", strerror(errno));
			shutdown(ipc_socket, SHUT_RDWR);
			rexit(-1);
		}

		/* Change into our new LSM profile. */
		on_exec = options->attach_flags & LXC_ATTACH_LSM_EXEC ? 1 : 0;
		if (lsm_set_label_at(lsm_labelfd, on_exec, init_ctx->lsm_label) < 0) {
			SYSERROR("Failed to set LSM label.");
			shutdown(ipc_socket, SHUT_RDWR);
			close(lsm_labelfd);
			rexit(-1);
		}
		close(lsm_labelfd);
	}

	if (init_ctx->container && init_ctx->container->lxc_conf &&
	    init_ctx->container->lxc_conf->seccomp &&
	    (lxc_seccomp_load(init_ctx->container->lxc_conf) != 0)) {
		ERROR("Loading seccomp policy");
		shutdown(ipc_socket, SHUT_RDWR);
		rexit(-1);
	}

	shutdown(ipc_socket, SHUT_RDWR);
	close(ipc_socket);
	lxc_proc_put_context_info(init_ctx);

	/* The following is done after the communication socket is
	 * shut down. That way, all errors that might (though
	 * unlikely) occur up until this point will have their messages
	 * printed to the original stderr (if logging is so configured)
	 * and not the fd the user supplied, if any.
	 */

	/* fd handling for stdin, stdout and stderr;
	 * ignore errors here, user may want to make sure
	 * the fds are closed, for example */
	if (options->stdin_fd >= 0 && options->stdin_fd != 0)
		dup2(options->stdin_fd, 0);
	if (options->stdout_fd >= 0 && options->stdout_fd != 1)
		dup2(options->stdout_fd, 1);
	if (options->stderr_fd >= 0 && options->stderr_fd != 2)
		dup2(options->stderr_fd, 2);

	/* close the old fds */
	if (options->stdin_fd > 2)
		close(options->stdin_fd);
	if (options->stdout_fd > 2)
		close(options->stdout_fd);
	if (options->stderr_fd > 2)
		close(options->stderr_fd);

	/* try to remove CLOEXEC flag from stdin/stdout/stderr,
	 * but also here, ignore errors */
	for (fd = 0; fd <= 2; fd++) {
		flags = fcntl(fd, F_GETFL);
		if (flags < 0)
			continue;
		if (flags & FD_CLOEXEC)
			if (fcntl(fd, F_SETFL, flags & ~FD_CLOEXEC) < 0)
				SYSERROR("Unable to clear CLOEXEC from fd");
	}

	/* we're done, so we can now do whatever the user intended us to do */
	rexit(payload->exec_function(payload->exec_payload));
}