/*
   *  Copyright (C) 2007
   *
   *  Author: Eric Biederman <ebiederm@xmision.com>
   *
   *  This program is free software; you can redistribute it and/or
   *  modify it under the terms of the GNU General Public License as
   *  published by the Free Software Foundation, version 2 of the
   *  License.
   */
  
  #include <linux/module.h>
  #include <linux/uts.h>
  #include <linux/utsname.h>

  #include <linux/sysctl.h>
  
  static void *get_uts(ctl_table *table, int write)
  {
  	char *which = table->data;

  	struct uts_namespace *uts_ns;
  
  	uts_ns = current->nsproxy->uts_ns;
  	which = (which - (char *)&init_uts_ns) + (char *)uts_ns;

  	if (!write)
  		down_read(&uts_sem);
  	else
  		down_write(&uts_sem);
  	return which;
  }
  
  static void put_uts(ctl_table *table, int write, void *which)
  {
  	if (!write)
  		up_read(&uts_sem);
  	else
  		up_write(&uts_sem);
  }
  
  #ifdef CONFIG_PROC_FS
  /*
   *	Special case of dostring for the UTS structure. This has locks
   *	to observe. Should this be in kernel/sys.c ????
   */
  static int proc_do_uts_string(ctl_table *table, int write, struct file *filp,
  		  void __user *buffer, size_t *lenp, loff_t *ppos)
  {
  	struct ctl_table uts_table;
  	int r;
  	memcpy(&uts_table, table, sizeof(uts_table));
  	uts_table.data = get_uts(table, write);
  	r = proc_dostring(&uts_table,write,filp,buffer,lenp, ppos);
  	put_uts(table, write, uts_table.data);
  	return r;
  }
  #else
  #define proc_do_uts_string NULL
  #endif
  
  
  #ifdef CONFIG_SYSCTL_SYSCALL
  /* The generic string strategy routine: */

  static int sysctl_uts_string(ctl_table *table,

  		  void __user *oldval, size_t __user *oldlenp,
  		  void __user *newval, size_t newlen)
  {
  	struct ctl_table uts_table;
  	int r, write;
  	write = newval && newlen;
  	memcpy(&uts_table, table, sizeof(uts_table));
  	uts_table.data = get_uts(table, write);

  	r = sysctl_string(&uts_table, oldval, oldlenp, newval, newlen);

  	put_uts(table, write, uts_table.data);
  	return r;
  }
  #else
  #define sysctl_uts_string NULL
  #endif
  
  static struct ctl_table uts_kern_table[] = {
  	{
  		.ctl_name	= KERN_OSTYPE,
  		.procname	= "ostype",
  		.data		= init_uts_ns.name.sysname,
  		.maxlen		= sizeof(init_uts_ns.name.sysname),
  		.mode		= 0444,
  		.proc_handler	= proc_do_uts_string,
  		.strategy	= sysctl_uts_string,
  	},
  	{
  		.ctl_name	= KERN_OSRELEASE,
  		.procname	= "osrelease",
  		.data		= init_uts_ns.name.release,
  		.maxlen		= sizeof(init_uts_ns.name.release),
  		.mode		= 0444,
  		.proc_handler	= proc_do_uts_string,
  		.strategy	= sysctl_uts_string,
  	},
  	{
  		.ctl_name	= KERN_VERSION,
  		.procname	= "version",
  		.data		= init_uts_ns.name.version,
  		.maxlen		= sizeof(init_uts_ns.name.version),
  		.mode		= 0444,
  		.proc_handler	= proc_do_uts_string,
  		.strategy	= sysctl_uts_string,
  	},
  	{
  		.ctl_name	= KERN_NODENAME,
  		.procname	= "hostname",
  		.data		= init_uts_ns.name.nodename,
  		.maxlen		= sizeof(init_uts_ns.name.nodename),
  		.mode		= 0644,
  		.proc_handler	= proc_do_uts_string,
  		.strategy	= sysctl_uts_string,
  	},
  	{
  		.ctl_name	= KERN_DOMAINNAME,
  		.procname	= "domainname",
  		.data		= init_uts_ns.name.domainname,
  		.maxlen		= sizeof(init_uts_ns.name.domainname),
  		.mode		= 0644,
  		.proc_handler	= proc_do_uts_string,
  		.strategy	= sysctl_uts_string,
  	},
  	{}
  };
  
  static struct ctl_table uts_root_table[] = {
  	{
  		.ctl_name	= CTL_KERN,
  		.procname	= "kernel",
  		.mode		= 0555,
  		.child		= uts_kern_table,
  	},
  	{}
  };
  
  static int __init utsname_sysctl_init(void)
  {

  	register_sysctl_table(uts_root_table);

  	return 0;
  }
  
  __initcall(utsname_sysctl_init);