Linux puskom-ProLiant-DL385-Gen10 5.4.0-150-generic #167~18.04.1-Ubuntu SMP Wed May 24 00:51:42 UTC 2023 x86_64

//usr/include/linux/nsfs.h

 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
#ifndef __LINUX_NSFS_H
#define __LINUX_NSFS_H

#include <linux/ioctl.h>

#define NSIO	0xb7

/* Returns a file descriptor that refers to an owning user namespace */
#define NS_GET_USERNS		_IO(NSIO, 0x1)
/* Returns a file descriptor that refers to a parent namespace */
#define NS_GET_PARENT		_IO(NSIO, 0x2)
/* Returns the type of namespace (CLONE_NEW* value) referred to by
   file descriptor */
#define NS_GET_NSTYPE		_IO(NSIO, 0x3)
/* Get owner UID (in the caller's user namespace) for a user namespace */
#define NS_GET_OWNER_UID	_IO(NSIO, 0x4)

#endif /* __LINUX_NSFS_H */