/*
 * linux/ipc/msg.c
 * Copyright (C) 1992 Krishna Balasubramanian
 *
 * Removed all the remaining kerneld mess
 * Catch the -EFAULT stuff properly
 * Use GFP_KERNEL for messages as in 1.2
 * Fixed up the unchecked user space derefs
 * Copyright (C) 1998 Alan Cox & Andi Kleen
 *
 * /proc/sysvipc/msg support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
 *
 * mostly rewritten, threaded and wake-one semantics added
 * MSGMAX limit removed, sysctl's added
 * (c) 1999 Manfred Spraul <manfred@colorfullife.com>
 *
 * support for audit of ipc object properties and permission changes
 * Dustin Kirkland <dustin.kirkland@us.ibm.com>
 *
 * namespaces support
 * OpenVZ, SWsoft Inc.
 * Pavel Emelianov <xemul@openvz.org>
 */

#include <linux/capability.h>
#include <linux/slab.h>
#include <linux/msg.h>
#include <linux/spinlock.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/proc_fs.h>
#include <linux/list.h>
#include <linux/security.h>
#include <linux/sched.h>
#include <linux/syscalls.h>
#include <linux/audit.h>
#include <linux/seq_file.h>
#include <linux/rwsem.h>
#include <linux/nsproxy.h>
#include <linux/ipc_namespace.h>

#include <asm/current.h>
#include <asm/uaccess.h>
#include "util.h"

/*
 * one msg_receiver structure for each sleeping receiver:
 */
struct msg_receiver {
	struct list_head	r_list;
	struct task_struct	*r_tsk;

	int			r_mode;
	long			r_msgtype;
	long			r_maxsize;

	struct msg_msg		*volatile r_msg;
};

/* one msg_sender for each sleeping sender */
struct msg_sender {
	struct list_head	list;
	struct task_struct	*tsk;
};

#define SEARCH_ANY		1
#define SEARCH_EQUAL		2
#define SEARCH_NOTEQUAL		3
#define SEARCH_LESSEQUAL	4

#define msg_ids(ns)	((ns)->ids[IPC_MSG_IDS])

#define msg_unlock(msq)		ipc_unlock(&(msq)->q_perm)

static void freeque(struct ipc_namespace *, struct kern_ipc_perm *);
static int newque(struct ipc_namespace *, struct ipc_params *);
#ifdef CONFIG_PROC_FS
static int sysvipc_msg_proc_show(struct seq_file *s, void *it);
#endif

/*
 * Scale msgmni with the available lowmem size: the memory dedicated to msg
 * queues should occupy at most 1/MSG_MEM_SCALE of lowmem.
 * Also take into account the number of nsproxies created so far.
 * This should be done staying within the (MSGMNI , IPCMNI/nr_ipc_ns) range.
 */
void recompute_msgmni(struct ipc_namespace *ns)
{
	struct sysinfo i;
	unsigned long allowed;
	int nb_ns;

	si_meminfo(&i);
	allowed = (((i.totalram - i.totalhigh) / MSG_MEM_SCALE) * i.mem_unit)
		/ MSGMNB;
	nb_ns = atomic_read(&nr_ipc_ns);
	allowed /= nb_ns;

	if (allowed < MSGMNI) {
		ns->msg_ctlmni = MSGMNI;
		return;
	}

	if (allowed > IPCMNI / nb_ns) {
		ns->msg_ctlmni = IPCMNI / nb_ns;
		return;
	}

	ns->msg_ctlmni = allowed;
}

void msg_init_ns(struct ipc_namespace *ns)
{
	ns->msg_ctlmax = MSGMAX;
	ns->msg_ctlmnb = MSGMNB;

	recompute_msgmni(ns);

	atomic_set(&ns->msg_bytes, 0);
	atomic_set(&ns->msg_hdrs, 0);
	ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
}

#ifdef CONFIG_IPC_NS
void msg_exit_ns(struct ipc_namespace *ns)
{
	free_ipcs(ns, &msg_ids(ns), freeque);
}
#endif

void __init msg_init(void)
{
	msg_init_ns(&init_ipc_ns);

	printk(KERN_INFO "msgmni has been set to %d\n",
		init_ipc_ns.msg_ctlmni);

	ipc_init_proc_interface("sysvipc/msg",
				"       key      msqid perms      cbytes       qnum lspid lrpid   uid   gid  cuid  cgid      stime      rtime      ctime\n",
				IPC_MSG_IDS, sysvipc_msg_proc_show);
}

/*
 * msg_lock_(check_) routines are called in the paths where the rw_mutex
 * is not held.
 */
static inline struct msg_queue *msg_lock(struct ipc_namespace *ns, int id)
{
	struct kern_ipc_perm *ipcp = ipc_lock(&msg_ids(ns), id);

	if (IS_ERR(ipcp))
		return (struct msg_queue *)ipcp;

	return container_of(ipcp, struct msg_queue, q_perm);
}

static inline struct msg_queue *msg_lock_check(struct ipc_namespace *ns,
						int id)
{
	struct kern_ipc_perm *ipcp = ipc_lock_check(&msg_ids(ns), id);

	if (IS_ERR(ipcp))
		return (struct msg_queue *)ipcp;

	return container_of(ipcp, struct msg_queue, q_perm);
}

static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
{
	ipc_rmid(&msg_ids(ns), &s->q_perm);
}

/**
 * newque - Create a new msg queue
 * @ns: namespace
 * @params: ptr to the structure that contains the key and msgflg
 *
 * Called with msg_ids.rw_mutex held (writer)
 */
static int newque(struct ipc_namespace *ns, struct ipc_params *params)
{
	struct msg_queue *msq;