/*
   *  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/ipc.h>
  #include <linux/nsproxy.h>
  #include <linux/sysctl.h>
  #include <linux/uaccess.h>

  #include <linux/ipc_namespace.h>

  #include <linux/msg.h>
  #include "util.h"

  static void *get_ipc(ctl_table *table)
  {
  	char *which = table->data;
  	struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
  	which = (which - (char *)&init_ipc_ns) + (char *)ipc_ns;
  	return which;
  }

  /*

   * Routine that is called when the file "auto_msgmni" has successfully been
   * written.
   * Two values are allowed:
   * 0: unregister msgmni's callback routine from the ipc namespace notifier
   *    chain. This means that msgmni won't be recomputed anymore upon memory
   *    add/remove or ipc namespace creation/removal.
   * 1: register back the callback routine.

   */

  static void ipc_auto_callback(int val)

  {

  	if (!val)

  		unregister_ipcns_notifier(current->nsproxy->ipc_ns);
  	else {
  		/*
  		 * Re-enable automatic recomputing only if not already
  		 * enabled.
  		 */
  		recompute_msgmni(current->nsproxy->ipc_ns);
  		cond_register_ipcns_notifier(current->nsproxy->ipc_ns);
  	}
  }

  #ifdef CONFIG_PROC_FS
  static int proc_ipc_dointvec(ctl_table *table, int write, struct file *filp,
  	void __user *buffer, size_t *lenp, loff_t *ppos)
  {
  	struct ctl_table ipc_table;
  	memcpy(&ipc_table, table, sizeof(ipc_table));
  	ipc_table.data = get_ipc(table);
  
  	return proc_dointvec(&ipc_table, write, filp, buffer, lenp, ppos);
  }

  static int proc_ipc_callback_dointvec(ctl_table *table, int write,
  	struct file *filp, void __user *buffer, size_t *lenp, loff_t *ppos)
  {

  	struct ctl_table ipc_table;

  	size_t lenp_bef = *lenp;
  	int rc;

  	memcpy(&ipc_table, table, sizeof(ipc_table));
  	ipc_table.data = get_ipc(table);
  
  	rc = proc_dointvec(&ipc_table, write, filp, buffer, lenp, ppos);

  
  	if (write && !rc && lenp_bef == *lenp)

  		/*
  		 * Tunable has successfully been changed by hand. Disable its
  		 * automatic adjustment. This simply requires unregistering
  		 * the notifiers that trigger recalculation.
  		 */
  		unregister_ipcns_notifier(current->nsproxy->ipc_ns);

  
  	return rc;
  }

  static int proc_ipc_doulongvec_minmax(ctl_table *table, int write,
  	struct file *filp, void __user *buffer, size_t *lenp, loff_t *ppos)
  {
  	struct ctl_table ipc_table;
  	memcpy(&ipc_table, table, sizeof(ipc_table));
  	ipc_table.data = get_ipc(table);
  
  	return proc_doulongvec_minmax(&ipc_table, write, filp, buffer,
  					lenp, ppos);
  }

  static int proc_ipcauto_dointvec_minmax(ctl_table *table, int write,
  	struct file *filp, void __user *buffer, size_t *lenp, loff_t *ppos)
  {
  	struct ctl_table ipc_table;
  	size_t lenp_bef = *lenp;
  	int oldval;
  	int rc;
  
  	memcpy(&ipc_table, table, sizeof(ipc_table));
  	ipc_table.data = get_ipc(table);
  	oldval = *((int *)(ipc_table.data));
  
  	rc = proc_dointvec_minmax(&ipc_table, write, filp, buffer, lenp, ppos);
  
  	if (write && !rc && lenp_bef == *lenp) {
  		int newval = *((int *)(ipc_table.data));
  		/*
  		 * The file "auto_msgmni" has correctly been set.
  		 * React by (un)registering the corresponding tunable, if the
  		 * value has changed.
  		 */
  		if (newval != oldval)
  			ipc_auto_callback(newval);
  	}
  
  	return rc;
  }

  #else
  #define proc_ipc_doulongvec_minmax NULL
  #define proc_ipc_dointvec	   NULL

  #define proc_ipc_callback_dointvec NULL

  #define proc_ipcauto_dointvec_minmax NULL

  #endif
  
  #ifdef CONFIG_SYSCTL_SYSCALL
  /* The generic sysctl ipc data routine. */
  static int sysctl_ipc_data(ctl_table *table, int __user *name, int nlen,
  		void __user *oldval, size_t __user *oldlenp,
  		void __user *newval, size_t newlen)
  {
  	size_t len;
  	void *data;
  
  	/* Get out of I don't have a variable */
  	if (!table->data || !table->maxlen)
  		return -ENOTDIR;
  
  	data = get_ipc(table);
  	if (!data)
  		return -ENOTDIR;
  
  	if (oldval && oldlenp) {
  		if (get_user(len, oldlenp))
  			return -EFAULT;
  		if (len) {
  			if (len > table->maxlen)
  				len = table->maxlen;
  			if (copy_to_user(oldval, data, len))
  				return -EFAULT;
  			if (put_user(len, oldlenp))
  				return -EFAULT;
  		}
  	}
  
  	if (newval && newlen) {
  		if (newlen > table->maxlen)
  			newlen = table->maxlen;
  
  		if (copy_from_user(data, newval, newlen))
  			return -EFAULT;
  	}
  	return 1;
  }

  
  static int sysctl_ipc_registered_data(ctl_table *table, int __user *name,
  		int nlen, void __user *oldval, size_t __user *oldlenp,
  		void __user *newval, size_t newlen)
  {
  	int rc;
  
  	rc = sysctl_ipc_data(table, name, nlen, oldval, oldlenp, newval,
  		newlen);

  	if (newval && newlen && rc > 0)

  		/*

  		 * Tunable has successfully been changed from userland

  		 */

  		unregister_ipcns_notifier(current->nsproxy->ipc_ns);

  
  	return rc;
  }

  #else
  #define sysctl_ipc_data NULL

  #define sysctl_ipc_registered_data NULL

  #endif

  static int zero;
  static int one = 1;

  static struct ctl_table ipc_kern_table[] = {
  	{
  		.ctl_name	= KERN_SHMMAX,
  		.procname	= "shmmax",
  		.data		= &init_ipc_ns.shm_ctlmax,
  		.maxlen		= sizeof (init_ipc_ns.shm_ctlmax),
  		.mode		= 0644,
  		.proc_handler	= proc_ipc_doulongvec_minmax,
  		.strategy	= sysctl_ipc_data,
  	},
  	{
  		.ctl_name	= KERN_SHMALL,
  		.procname	= "shmall",
  		.data		= &init_ipc_ns.shm_ctlall,
  		.maxlen		= sizeof (init_ipc_ns.shm_ctlall),
  		.mode		= 0644,
  		.proc_handler	= proc_ipc_doulongvec_minmax,
  		.strategy	= sysctl_ipc_data,
  	},
  	{
  		.ctl_name	= KERN_SHMMNI,
  		.procname	= "shmmni",
  		.data		= &init_ipc_ns.shm_ctlmni,
  		.maxlen		= sizeof (init_ipc_ns.shm_ctlmni),
  		.mode		= 0644,
  		.proc_handler	= proc_ipc_dointvec,
  		.strategy	= sysctl_ipc_data,
  	},
  	{
  		.ctl_name	= KERN_MSGMAX,
  		.procname	= "msgmax",
  		.data		= &init_ipc_ns.msg_ctlmax,
  		.maxlen		= sizeof (init_ipc_ns.msg_ctlmax),
  		.mode		= 0644,
  		.proc_handler	= proc_ipc_dointvec,
  		.strategy	= sysctl_ipc_data,
  	},
  	{
  		.ctl_name	= KERN_MSGMNI,
  		.procname	= "msgmni",
  		.data		= &init_ipc_ns.msg_ctlmni,
  		.maxlen		= sizeof (init_ipc_ns.msg_ctlmni),
  		.mode		= 0644,

  		.proc_handler	= proc_ipc_callback_dointvec,
  		.strategy	= sysctl_ipc_registered_data,

  	},
  	{
  		.ctl_name	= KERN_MSGMNB,
  		.procname	=  "msgmnb",
  		.data		= &init_ipc_ns.msg_ctlmnb,
  		.maxlen		= sizeof (init_ipc_ns.msg_ctlmnb),
  		.mode		= 0644,
  		.proc_handler	= proc_ipc_dointvec,
  		.strategy	= sysctl_ipc_data,
  	},
  	{
  		.ctl_name	= KERN_SEM,
  		.procname	= "sem",
  		.data		= &init_ipc_ns.sem_ctls,
  		.maxlen		= 4*sizeof (int),
  		.mode		= 0644,
  		.proc_handler	= proc_ipc_dointvec,
  		.strategy	= sysctl_ipc_data,
  	},

  	{
  		.ctl_name	= CTL_UNNUMBERED,
  		.procname	= "auto_msgmni",
  		.data		= &init_ipc_ns.auto_msgmni,
  		.maxlen		= sizeof(int),
  		.mode		= 0644,
  		.proc_handler	= proc_ipcauto_dointvec_minmax,
  		.extra1		= &zero,
  		.extra2		= &one,
  	},

  	{}
  };
  
  static struct ctl_table ipc_root_table[] = {
  	{
  		.ctl_name	= CTL_KERN,
  		.procname	= "kernel",
  		.mode		= 0555,
  		.child		= ipc_kern_table,
  	},
  	{}
  };
  
  static int __init ipc_sysctl_init(void)
  {

  	register_sysctl_table(ipc_root_table);

  	return 0;
  }
  
  __initcall(ipc_sysctl_init);