/*
* linux/ipc/util.c
* Copyright (C) 1992 Krishna Balasubramanian
*
* Sep 1997 - Call suser() last after "normal" permission checks so we
* get BSD style process accounting right.
* Occurs in several places in the IPC code.
* Chris Evans, <chris@ferret.lmh.ox.ac.uk>
* Nov 1999 - ipc helper functions, unified SMP locking
* Manfred Spraul <manfred@colorfullife.com>
* Oct 2002 - One lock per IPC id. RCU ipc_free for lock-free grow_ary().
* Mingming Cao <cmm@us.ibm.com>
* Mar 2006 - support for audit of ipc object properties
* Dustin Kirkland <dustin.kirkland@us.ibm.com>
* Jun 2006 - namespaces ssupport
* OpenVZ, SWsoft Inc.
* Pavel Emelianov <xemul@openvz.org>
*/
#include <linux/mm.h>
#include <linux/shm.h>
#include <linux/init.h>
#include <linux/msg.h>
#include <linux/vmalloc.h>
#include <linux/slab.h>
#include <linux/notifier.h>
#include <linux/capability.h>
#include <linux/highuid.h>
#include <linux/security.h>
#include <linux/rcupdate.h>
#include <linux/workqueue.h>
#include <linux/seq_file.h>
#include <linux/proc_fs.h>
#include <linux/audit.h>
#include <linux/nsproxy.h>
#include <linux/rwsem.h>
#include <linux/memory.h>
#include <linux/ipc_namespace.h>
#include <asm/unistd.h>
#include "util.h"
struct ipc_proc_iface {
const char *path;
const char *header;
int ids;
int (*show)(struct seq_file *, void *);
};
static void ipc_memory_notifier(struct work_struct *work)
{
ipcns_notify(IPCNS_MEMCHANGED);
}
static int ipc_memory_callback(struct notifier_block *self,
unsigned long action, void *arg)
{
static DECLARE_WORK(ipc_memory_wq, ipc_memory_notifier);
switch (action) {
case MEM_ONLINE: /* memory successfully brought online */
case MEM_OFFLINE: /* or offline: it's time to recompute msgmni */
/*
* This is done by invoking the ipcns notifier chain with the
* IPC_MEMCHANGED event.
* In order not to keep the lock on the hotplug memory chain
* for too long, queue a work item that will, when waken up,
* activate the ipcns notification chain.
* No need to keep several ipc work items on the queue.
*/
if (!work_pending(&ipc_memory_wq))
schedule_work(&ipc_memory_wq);
break;
case MEM_GOING_ONLINE:
case MEM_GOING_OFFLINE:
case MEM_CANCEL_ONLINE:
case MEM_CANCEL_OFFLINE:
default:
break;
}
return NOTIFY_OK;
}
static struct notifier_block ipc_memory_nb = {
.notifier_call = ipc_memory_callback,
.priority = IPC_CALLBACK_PRI,
};
/**
* ipc_init - initialise IPC subsystem
*
* The various system5 IPC resources (semaphores, messages and shared
* memory) are initialised
* A callback routine is registered into the memory hotplug notifier
* chain: since msgmni scales to lowmem this callback routine will be
* called upon successful memory add / remove to recompute msmgni.
*/
static int __init ipc_init(void)
{
sem_init();
msg_init();
shm_init();
register_hotmemory_notifier(&ipc_memory_nb);
register_ipcns_notifier(&init_ipc_ns);
return 0;
}
__initcall(ipc_init);
/**
* ipc_init_ids - initialise IPC identifiers
* @ids: Identifier set
*
* Set up the sequence range to use for the ipc identifier range (limited
* below IPCMNI) then initialise the ids idr.
*/
void ipc_init_ids(struct ipc_ids *ids)
{
init_rwsem(&ids->rw_mutex);
ids->in_use = 0;
ids->seq = 0;
ids->next_id = -1;
{
int seq_limit = INT_MAX/SEQ_MULTIPLIER;
if (seq_limit > USHRT_MAX)
ids->seq_max = USHRT_MAX;
else
ids->seq_max = seq_limit;
}
idr_init(&ids->ipcs_idr);
}
#ifdef CONFIG_PROC_FS
static const struct file_operations sysvipc_proc_fops;
/**
* ipc_init_proc_interface - Create a proc interface for sysipc types using a seq_file interface.
* @path: Path in procfs
* @header: Banner to be printed at the beginning of the file.
* @ids: ipc id table to iterate.
* @show: show routine.
*/
void __init ipc_init_proc_interface(const char *path, const char *header,
int ids, int (*show)(struct seq_file *, void *))
{
struct proc_dir_entry *pde;
struct ipc_proc_iface *iface;
iface = kmalloc(sizeof(*iface), GFP_KERNEL);
if (!iface)
return;
iface->path = path;
iface->header = header;
iface->ids = ids;
iface->show = show;
pde = proc_create_data(path,
S_IRUGO, /* world readable */
NULL, /* parent dir */
&sysvipc_proc_fops,
iface);
if (!pde) {
kfree(iface);
}
}
#endif
/**
* ipc_findkey - find a key in an ipc identifier set
* @ids: Identifier set
* @key: The key to find
*
* Requires ipc_ids.rw_mutex locked.
* Returns the LOCKED pointer to the ipc structure if found or NULL
* if not.
* If key is found ipc points to the owning ipc structure
*/
static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
{
struct kern_ipc_perm *ipc;
int next_id;
int total;