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/rwsem.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 struct ipc_ids init_msg_ids;

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

#define msg_unlock(msq)		ipc_unlock(&(msq)->q_perm)
#define msg_buildid(id, seq)	ipc_buildid(id, seq)

static void freeque(struct ipc_namespace *, struct msg_queue *);
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

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

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)
{
	struct msg_queue *msq;
	struct kern_ipc_perm *perm;
	int next_id;
	int total, in_use;

	down_write(&msg_ids(ns).rw_mutex);

	in_use = msg_ids(ns).in_use;

	for (total = 0, next_id = 0; total < in_use; next_id++) {
		perm = idr_find(&msg_ids(ns).ipcs_idr, next_id);
		if (perm == NULL)
			continue;
		ipc_lock_by_ptr(perm);
		msq = container_of(perm, struct msg_queue, q_perm);
		freeque(ns, msq);
		total++;
	}

	up_write(&msg_ids(ns).rw_mutex);

	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);
}

/*
 * This routine is called in the paths where the rw_mutex is held to protect
 * access to the idr tree.
 */
static inline struct msg_queue *msg_lock_check_down(struct ipc_namespace *ns,
						int id)
{
	struct kern_ipc_perm *ipcp = ipc_lock_check_down(&msg_ids(ns), id);

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

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

/*
 * 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,