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/*
* 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;
}

#ifdef CONFIG_PROC_SYSCTL
static int proc_ipc_dointvec(ctl_table *table, int write,
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, buffer, lenp, ppos);
}

static int proc_ipc_callback_dointvec(ctl_table *table, int write,
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, 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,
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, buffer,
lenp, ppos);
}

/*
* 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);
}
}

static int proc_ipcauto_dointvec_minmax(ctl_table *table, int write,
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, 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

static int zero;
static int one = 1;

static struct ctl_table ipc_kern_table[] = {
{
.procname = "shmmax",
.data = &init_ipc_ns.shm_ctlmax,
.maxlen = sizeof (init_ipc_ns.shm_ctlmax),
.mode = 0644,
.proc_handler = proc_ipc_doulongvec_minmax,
},
{
.procname = "shmall",
.data = &init_ipc_ns.shm_ctlall,
.maxlen = sizeof (init_ipc_ns.shm_ctlall),
.mode = 0644,
.proc_handler = proc_ipc_doulongvec_minmax,
},
{
.procname = "shmmni",
.data = &init_ipc_ns.shm_ctlmni,
.maxlen = sizeof (init_ipc_ns.shm_ctlmni),
.mode = 0644,
.proc_handler = proc_ipc_dointvec,
},
{
.procname = "msgmax",
.data = &init_ipc_ns.msg_ctlmax,
.maxlen = sizeof (init_ipc_ns.msg_ctlmax),
.mode = 0644,
.proc_handler = proc_ipc_dointvec,
},
{
.procname = "msgmni",
.data = &init_ipc_ns.msg_ctlmni,
.maxlen = sizeof (init_ipc_ns.msg_ctlmni),
.mode = 0644,
.proc_handler = proc_ipc_callback_dointvec,
},
{
.procname = "msgmnb",
.data = &init_ipc_ns.msg_ctlmnb,
.maxlen = sizeof (init_ipc_ns.msg_ctlmnb),
.mode = 0644,
.proc_handler = proc_ipc_dointvec,
},
{
.procname = "sem",
.data = &init_ipc_ns.sem_ctls,
.maxlen = 4*sizeof (int),
.mode = 0644,
.proc_handler = proc_ipc_dointvec,
},
{
.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[] = {
{
.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);
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