path: root/ipc/mqueue.c

/*
 * POSIX message queues filesystem for Linux.
 *
 * Copyright (C) 2003,2004  Krzysztof Benedyczak    (golbi@mat.uni.torun.pl)
 *                          Michal Wronski          (michal.wronski@gmail.com)
 *
 * Spinlocks:               Mohamed Abbas           (abbas.mohamed@intel.com)
 * Lockless receive & send, fd based notify:
 * 			    Manfred Spraul	    (manfred@colorfullife.com)
 *
 * Audit:                   George Wilson           (ltcgcw@us.ibm.com)
 *
 * This file is released under the GPL.
 */

#include <linux/capability.h>
#include <linux/init.h>
#include <linux/pagemap.h>
#include <linux/file.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/sysctl.h>
#include <linux/poll.h>
#include <linux/mqueue.h>
#include <linux/msg.h>
#include <linux/skbuff.h>
#include <linux/netlink.h>
#include <linux/syscalls.h>
#include <linux/audit.h>
#include <linux/signal.h>
#include <linux/mutex.h>
#include <linux/nsproxy.h>
#include <linux/pid.h>
#include <linux/ipc_namespace.h>
#include <linux/slab.h>

#include <net/sock.h>
#include "util.h"

#define MQUEUE_MAGIC	0x19800202
#define DIRENT_SIZE	20
#define FILENT_SIZE	80

#define SEND		0
#define RECV		1

#define STATE_NONE	0
#define STATE_PENDING	1
#define STATE_READY	2

struct ext_wait_queue {		/* queue of sleeping tasks */
	struct task_struct *task;
	struct list_head list;
	struct msg_msg *msg;	/* ptr of loaded message */
	int state;		/* one of STATE_* values */
};

struct mqueue_inode_info {
	spinlock_t lock;
	struct inode vfs_inode;
	wait_queue_head_t wait_q;

	struct msg_msg **messages;
	struct mq_attr attr;

	struct sigevent notify;
	struct pid* notify_owner;
	struct user_struct *user;	/* user who created, for accounting */
	struct sock *notify_sock;
	struct sk_buff *notify_cookie;

	/* for tasks waiting for free space and messages, respectively */
	struct ext_wait_queue e_wait_q[2];

	unsigned long qsize; /* size of queue in memory (sum of all msgs) */
};

static const struct inode_operations mqueue_dir_inode_operations;
static const struct file_operations mqueue_file_operations;
static const struct super_operations mqueue_super_ops;
static void remove_notification(struct mqueue_inode_info *info);

static struct kmem_cache *mqueue_inode_cachep;

static struct ctl_table_header * mq_sysctl_table;

static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
{
	return container_of(inode, struct mqueue_inode_info, vfs_inode);
}

/*
 * This routine should be called with the mq_lock held.
 */
static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
{
	return get_ipc_ns(inode->i_sb->s_fs_info);
}

static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
{
	struct ipc_namespace *ns;

	spin_lock(&mq_lock);
	ns = __get_ns_from_inode(inode);
	spin_unlock(&mq_lock);
	return ns;
}

static struct inode *mqueue_get_inode(struct super_block *sb,
		struct ipc_namespace *ipc_ns, int mode,
		struct mq_attr *attr)
{
	struct user_struct *u = current_user();
	struct inode *inode;

	inode = new_inode(sb);
	if (inode) {
		inode->i_mode = mode;
		inode->i_uid = current_fsuid();
		inode->i_gid = current_fsgid();
		inode->i_mtime = inode->i_ctime = inode->i_atime =
				CURRENT_TIME;

		if (S_ISREG(mode)) {
			struct mqueue_inode_info *info;
			struct task_struct *p = current;
			unsigned long mq_bytes, mq_msg_tblsz;

			inode->i_fop = &mqueue_file_operations;
			inode->i_size = FILENT_SIZE;
			/* mqueue specific info */
			info = MQUEUE_I(inode);
			spin_lock_init(&info->lock);
			init_waitqueue_head(&info->wait_q);
			INIT_LIST_HEAD(&info->e_wait_q[0].list);
			INIT_LIST_HEAD(&info->e_wait_q[1].list);
			info->notify_owner = NULL;
			info->qsize = 0;
			info->user = NULL;	/* set when all is ok */
			memset(&info->attr, 0, sizeof(info->attr));
			info->attr.mq_maxmsg = ipc_ns->mq_msg_max;
			info->attr.mq_msgsize = ipc_ns->mq_msgsize_max;
			if (attr) {
				info->attr.mq_maxmsg = attr->mq_maxmsg;
				info->attr.mq_msgsize = attr->mq_msgsize;
			}
			mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
			info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
			if (!info->messages)
				goto out_inode;

			mq_bytes = (mq_msg_tblsz +
				(info->attr.mq_maxmsg * info->attr.mq_msgsize));

			spin_lock(&mq_lock);
			if (u->mq_bytes + mq_bytes < u->mq_bytes ||
		 	    u->mq_bytes + mq_bytes >
			    task_rlimit(p, RLIMIT_MSGQUEUE)) {
				spin_unlock(&mq_lock);
				kfree(info->messages);
				goto out_inode;
			}
			u->mq_bytes += mq_bytes;
			spin_unlock(&mq_lock);

			/* all is ok */
			info<