path: root/ipc/msg.c

/*
 * 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