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/*
 * 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/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/mutex.h>
#include <linux/nsproxy.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

static atomic_t msg_bytes =	ATOMIC_INIT(0);
static atomic_t msg_hdrs =	ATOMIC_INIT(0);

static struct ipc_ids init_msg_ids;

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

#define msg_lock(ns, id)	((struct msg_queue*)ipc_lock(&msg_ids(ns), id))
#define msg_unlock(msq)		ipc_unlock(&(msq)->q_perm)
#define msg_rmid(ns, id)	((struct msg_queue*)ipc_rmid(&msg_ids(ns), id))
#define msg_checkid(ns, msq, msgid)	\
	ipc_checkid(&msg_ids(ns), &msq->q_perm, msgid)
#define msg_buildid(ns, id, seq) \
	ipc_buildid(&msg_ids(ns), id, seq)

static void freeque (struct ipc_namespace *ns, struct msg_queue *msq, int id);
static int newque (struct ipc_namespace *ns, key_t key, int msgflg);
#ifdef CONFIG_PROC_FS
static int sysvipc_msg_proc_show(struct seq_file *s, void *it);
#endif

static void __msg_init_ns(struct ipc_namespace *ns, struct ipc_ids *ids)
{
	ns->ids[IPC_MSG_IDS] = ids;
	ns->msg_ctlmax = MSGMAX;
	ns->msg_ctlmnb = MSGMNB;
	ns->msg_ctlmni = MSGMNI;
	ipc_init_ids(ids, ns->msg_ctlmni);
}

int msg_init_ns(struct ipc_namespace *ns)
{
	struct ipc_ids *ids;

	ids = kmalloc(sizeof(struct ipc_ids), GFP_KERNEL);
	if (ids == NULL)
		return -ENOMEM;

	__msg_init_ns(ns, ids);
	return 0;
}

void msg_exit_ns(struct ipc_namespace *ns)
{
	int i;
	struct msg_queue *msq;

	mutex_lock(&msg_ids(ns).mutex);
	for (i = 0; i <= msg_ids(ns).max_id; i++) {
		msq = msg_lock(ns, i);
		if (msq == NULL)
			continue;

		freeque(ns, msq, i);
	}
	mutex_unlock(&msg_ids(ns).mutex);

	ipc_fini_ids(ns->ids[IPC_MSG_IDS]);
	kfree(ns->ids[IPC_MSG_IDS]);
	ns->ids[IPC_MSG_IDS] = NULL;
}

void __init msg_init(void)
{
	__msg_init_ns(&init_ipc_ns, &init_msg_ids);
	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);
}

static int newque (struct ipc_namespace *ns, key_t key, int msgflg)
{
	struct msg_queue *msq;
	int id, retval;

	msq = ipc_rcu_alloc(sizeof(*msq));
	if (!msq)
		return -ENOMEM;

	msq->q_perm.mode = msgflg & S_IRWXUGO;
	msq->q_perm.key = key;

	msq->q_perm.security = NULL;
	retval = security_msg_queue_alloc(msq);
	if (retval) {
		ipc_rcu_putref(msq);
		return retval;
	}

	id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
	if (id == -1) {
		security_msg_queue_free(msq);
		ipc_rcu_putref(msq);
		return -ENOSPC;
	}

	msq->q_id = msg_buildid(ns, id, msq->q_perm.seq);
	msq->q_stime = msq->q_rtime = 0;
	msq->q_ctime = get_seconds();
	msq->q_cbytes = msq->q_qnum = 0;
	msq->q_qbytes = ns->msg_ctlmnb;
	msq->q_lspid = msq->q_lrpid = 0;
	INIT_LIST_HEAD(&msq->q_messages);
	INIT_LIST_HEAD(&msq->q_receivers);
	INIT_LIST_HEAD(&msq->q_senders);
	msg_unlock(msq);

	return msq->q_id;
}

static inline void ss_add(struct msg_queue *msq, struct msg_sender *mss)
{
	mss->tsk = current;
	current->state = TASK_INTERRUPTIBLE;
	list_add_tail(&mss->list, &msq->q_senders);
}

static inline void ss_del(struct msg_sender *mss)
{
	if (mss->list.next != NULL)
		list_del(&mss->list);
}

static void ss_wakeup(struct list_head *h, int kill)
{
	struct list_head *tmp;

	tmp = h->next;
	while (tmp != h) {
		struct msg_sender *mss;

		mss = list_entry(tmp, struct msg_sender, list);
		tmp = tmp->next;
		if (kill)
			mss->list.next = NULL;
		wake_up_process(mss->tsk);
	}
}

static void expunge_all(struct msg_queue *msq, int res)
{
	struct list_head *tmp;

	tmp = msq->q_receivers.next;
	while (tmp != &msq->q_receivers) {
		struct msg_receiver *msr;

		msr = list_entry(tmp, struct msg_receiver, r_list);
		tmp = tmp->next;
		msr->r_msg = NULL;
		wake_up_process(msr->r_tsk);
		smp_mb();
		msr->r_msg = ERR_PTR(res);
	}
}

/*
 * freeque() wakes up waiters on the sender and receiver waiting queue,
 * removes the message queue from message queue ID
 * array, and cleans up all the messages associated with this queue.
 *
 * msg_ids.mutex and the spinlock for this message queue is hold
 * before freeque() is called. msg_ids.mutex remains locked on exit.
 */
static void freeque(struct ipc_namespace *ns, struct msg_queue *msq, int id)
{
	struct list_head *tmp;

	expunge_all(msq, -EIDRM);
	ss_wakeup(&msq->q_senders, 1);
	msq = msg_rmid(ns, id);
	msg_unlock(msq);

	tmp = msq->q_messages.next;
	while (tmp != &msq->q_messages) {
		struct msg_msg *msg = list_entry(tmp, struct msg_msg, m_list);

		tmp = tmp->next;
		atomic_dec(&msg_hdrs);
		free_msg(msg);
	}
	atomic_sub(msq->q_cbytes, &msg_bytes);
	security_msg_queue_free(msq);
	ipc_rcu_putref(msq);
}

asmlinkage long sys_msgget(key_t key, int msgflg)
{
	struct msg_queue *msq;
	int id, ret = -EPERM;
	struct ipc_namespace *ns;

	ns = current->nsproxy->ipc_ns;
	
	mutex_lock(&msg_ids(ns).mutex);
	if (key == IPC_PRIVATE) 
		ret = newque(ns, key, msgflg);
	else if ((id = ipc_findkey(&msg_ids(ns), key)) == -1) { /* key not used */
		if (!(msgflg & IPC_CREAT))
			ret = -ENOENT;
		else
			ret = newque(ns, key, msgflg);
	} else if (msgflg & IPC_CREAT && msgflg & IPC_EXCL) {
		ret = -EEXIST;
	} else {
		msq = msg_lock(ns, id);
		BUG_ON(msq == NULL);
		if (ipcperms(&msq->q_perm, msgflg))
			ret = -EACCES;
		else {
			int qid = msg_buildid(ns, id, msq->q_perm.seq);

			ret = security_msg_queue_associate(msq, msgflg);
			if (!ret)
				ret = qid;
		}
		msg_unlock(msq);
	}
	mutex_unlock(&msg_ids(ns).mutex);

	return ret;
}

static inline unsigned long
copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
{
	switch(version) {
	case IPC_64:
		return copy_to_user(buf, in, sizeof(*in));
	case IPC_OLD:
	{
		struct msqid_ds out;

		memset(&out, 0, sizeof(out));

		ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);

		out.msg_stime		= in->msg_stime;
		out.msg_rtime		= in->msg_rtime;
		out.msg_ctime		= in->msg_ctime;

		if (in->msg_cbytes > USHRT_MAX)
			out.msg_cbytes	= USHRT_MAX;
		else
			out.msg_cbytes	= in->msg_cbytes;
		out.msg_lcbytes		= in->msg_cbytes;

		if (in->msg_qnum > USHRT_MAX)
			out.msg_qnum	= USHRT_MAX;
		else
			out.msg_qnum	= in->msg_qnum;

		if (in->msg_qbytes > USHRT_MAX)
			out.msg_qbytes	= USHRT_MAX;
		else
			out.msg_qbytes	= in->msg_qbytes;
		out.msg_lqbytes		= in->msg_qbytes;

		out.msg_lspid		= in->msg_lspid;
		out.msg_lrpid		= in->msg_lrpid;

		return copy_to_user(buf, &out, sizeof(out));
	}
	default:
		return -EINVAL;
	}
}

struct msq_setbuf {
	unsigned long	qbytes;
	uid_t		uid;
	gid_t		gid;
	mode_t		mode;
};

static inline unsigned long
copy_msqid_from_user(struct msq_setbuf *out, void __user *buf, int version)
{
	switch(version) {
	case IPC_64:
	{
		struct msqid64_ds tbuf;

		if (copy_from_user(&tbuf, buf, sizeof(tbuf)))
			return -EFAULT;

		out->qbytes		= tbuf.msg_qbytes;
		out->uid		= tbuf.msg_perm.uid;
		out->gid		= tbuf.msg_perm.gid;
		out->mode		= tbuf.msg_perm.mode;

		return 0;
	}
	case IPC_OLD:
	{
		struct msqid_ds tbuf_old;

		if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
			return -EFAULT;

		out->uid		= tbuf_old.msg_perm.uid;
		out->gid		= tbuf_old.msg_perm.gid;
		out->mode		= tbuf_old.msg_perm.mode;

		if (tbuf_old.msg_qbytes == 0)
			out->qbytes	= tbuf_old.msg_lqbytes;
		else
			out->qbytes	= tbuf_old.msg_qbytes;

		return 0;
	}
	default:
		return -EINVAL;
	}
}

asmlinkage long sys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf)
{
	struct kern_ipc_perm *ipcp;
	struct msq_setbuf uninitialized_var(setbuf);
	struct msg_queue *msq;