Logo Search packages:      
Sourcecode: linux version File versions  Download package

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 <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

/* default values */
#define DFLT_QUEUESMAX  256   /* max number of message queues */
#define DFLT_MSGMAX     10    /* max number of messages in each queue */
#define HARD_MSGMAX     (131072/sizeof(void*))
#define DFLT_MSGSIZEMAX 8192  /* max message size */


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 struct super_operations mqueue_super_ops;
static void remove_notification(struct mqueue_inode_info *info);

static spinlock_t mq_lock;
static struct kmem_cache *mqueue_inode_cachep;
static struct vfsmount *mqueue_mnt;

static unsigned int queues_count;
static unsigned int queues_max      = DFLT_QUEUESMAX;
static unsigned int msg_max   = DFLT_MSGMAX;
static unsigned int msgsize_max = DFLT_MSGSIZEMAX;

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);
}

static struct inode *mqueue_get_inode(struct super_block *sb, int mode,
                                          struct mq_attr *attr)
{
      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_blocks = 0;
            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;
                  struct user_struct *u = p->user;
                  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->messages = NULL;
                  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 = DFLT_MSGMAX;
                  info->attr.mq_msgsize = DFLT_MSGSIZEMAX;
                  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 *);
                  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 >
                      p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
                        spin_unlock(&mq_lock);
                        goto out_inode;
                  }
                  u->mq_bytes += mq_bytes;
                  spin_unlock(&mq_lock);

                  info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
                  if (!info->messages) {
                        spin_lock(&mq_lock);
                        u->mq_bytes -= mq_bytes;
                        spin_unlock(&mq_lock);
                        goto out_inode;
                  }
                  /* all is ok */
                  info->user = get_uid(u);
            } else if (S_ISDIR(mode)) {
                  inc_nlink(inode);
                  /* Some things misbehave if size == 0 on a directory */
                  inode->i_size = 2 * DIRENT_SIZE;
                  inode->i_op = &mqueue_dir_inode_operations;
                  inode->i_fop = &simple_dir_operations;
            }
      }
      return inode;
out_inode:
      make_bad_inode(inode);
      iput(inode);
      return NULL;
}

static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
{
      struct inode *inode;

      sb->s_blocksize = PAGE_CACHE_SIZE;
      sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
      sb->s_magic = MQUEUE_MAGIC;
      sb->s_op = &mqueue_super_ops;

      inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
      if (!inode)
            return -ENOMEM;

      sb->s_root = d_alloc_root(inode);
      if (!sb->s_root) {
            iput(inode);
            return -ENOMEM;
      }

      return 0;
}

static int mqueue_get_sb(struct file_system_type *fs_type,
                   int flags, const char *dev_name,
                   void *data, struct vfsmount *mnt)
{
      return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt);
}

static void init_once(struct kmem_cache *cachep, void *foo)
{
      struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;

      inode_init_once(&p->vfs_inode);
}

static struct inode *mqueue_alloc_inode(struct super_block *sb)
{
      struct mqueue_inode_info *ei;

      ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
      if (!ei)
            return NULL;
      return &ei->vfs_inode;
}

static void mqueue_destroy_inode(struct inode *inode)
{
      kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
}

static void mqueue_delete_inode(struct inode *inode)
{
      struct mqueue_inode_info *info;
      struct user_struct *user;
      unsigned long mq_bytes;
      int i;

      if (S_ISDIR(inode->i_mode)) {
            clear_inode(inode);
            return;
      }
      info = MQUEUE_I(inode);
      spin_lock(&info->lock);
      for (i = 0; i < info->attr.mq_curmsgs; i++)
            free_msg(info->messages[i]);
      kfree(info->messages);
      spin_unlock(&info->lock);

      clear_inode(inode);

      mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
               (info->attr.mq_maxmsg * info->attr.mq_msgsize));
      user = info->user;
      if (user) {
            spin_lock(&mq_lock);
            user->mq_bytes -= mq_bytes;
            queues_count--;
            spin_unlock(&mq_lock);
            free_uid(user);
      }
}

static int mqueue_create(struct inode *dir, struct dentry *dentry,
                        int mode, struct nameidata *nd)
{
      struct inode *inode;
      struct mq_attr *attr = dentry->d_fsdata;
      int error;

      spin_lock(&mq_lock);
      if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
            error = -ENOSPC;
            goto out_lock;
      }
      queues_count++;
      spin_unlock(&mq_lock);

      inode = mqueue_get_inode(dir->i_sb, mode, attr);
      if (!inode) {
            error = -ENOMEM;
            spin_lock(&mq_lock);
            queues_count--;
            goto out_lock;
      }

      dir->i_size += DIRENT_SIZE;
      dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;

      d_instantiate(dentry, inode);
      dget(dentry);
      return 0;
out_lock:
      spin_unlock(&mq_lock);
      return error;
}

static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
{
      struct inode *inode = dentry->d_inode;

      dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
      dir->i_size -= DIRENT_SIZE;
      drop_nlink(inode);
      dput(dentry);
      return 0;
}

/*
*     This is routine for system read from queue file.
*     To avoid mess with doing here some sort of mq_receive we allow
*     to read only queue size & notification info (the only values
*     that are interesting from user point of view and aren't accessible
*     through std routines)
*/
static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
                        size_t count, loff_t * off)
{
      struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
      char buffer[FILENT_SIZE];
      size_t slen;
      loff_t o;

      if (!count)
            return 0;

      spin_lock(&info->lock);
      snprintf(buffer, sizeof(buffer),
                  "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
                  info->qsize,
                  info->notify_owner ? info->notify.sigev_notify : 0,
                  (info->notify_owner &&
                   info->notify.sigev_notify == SIGEV_SIGNAL) ?
                        info->notify.sigev_signo : 0,
                  pid_nr_ns(info->notify_owner,
                        current->nsproxy->pid_ns));
      spin_unlock(&info->lock);
      buffer[sizeof(buffer)-1] = '\0';
      slen = strlen(buffer)+1;

      o = *off;
      if (o > slen)
            return 0;

      if (o + count > slen)
            count = slen - o;

      if (copy_to_user(u_data, buffer + o, count))
            return -EFAULT;

      *off = o + count;
      filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
      return count;
}

static int mqueue_flush_file(struct file *filp, fl_owner_t id)
{
      struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);

      spin_lock(&info->lock);
      if (task_tgid(current) == info->notify_owner)
            remove_notification(info);

      spin_unlock(&info->lock);
      return 0;
}

static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
{
      struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
      int retval = 0;

      poll_wait(filp, &info->wait_q, poll_tab);

      spin_lock(&info->lock);
      if (info->attr.mq_curmsgs)
            retval = POLLIN | POLLRDNORM;

      if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
            retval |= POLLOUT | POLLWRNORM;
      spin_unlock(&info->lock);

      return retval;
}

/* Adds current to info->e_wait_q[sr] before element with smaller prio */
static void wq_add(struct mqueue_inode_info *info, int sr,
                  struct ext_wait_queue *ewp)
{
      struct ext_wait_queue *walk;

      ewp->task = current;

      list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
            if (walk->task->static_prio <= current->static_prio) {
                  list_add_tail(&ewp->list, &walk->list);
                  return;
            }
      }
      list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
}

/*
 * Puts current task to sleep. Caller must hold queue lock. After return
 * lock isn't held.
 * sr: SEND or RECV
 */
static int wq_sleep(struct mqueue_inode_info *info, int sr,
                  long timeout, struct ext_wait_queue *ewp)
{
      int retval;
      signed long time;

      wq_add(info, sr, ewp);

      for (;;) {
            set_current_state(TASK_INTERRUPTIBLE);

            spin_unlock(&info->lock);
            time = schedule_timeout(timeout);

            while (ewp->state == STATE_PENDING)
                  cpu_relax();

            if (ewp->state == STATE_READY) {
                  retval = 0;
                  goto out;
            }
            spin_lock(&info->lock);
            if (ewp->state == STATE_READY) {
                  retval = 0;
                  goto out_unlock;
            }
            if (signal_pending(current)) {
                  retval = -ERESTARTSYS;
                  break;
            }
            if (time == 0) {
                  retval = -ETIMEDOUT;
                  break;
            }
      }
      list_del(&ewp->list);
out_unlock:
      spin_unlock(&info->lock);
out:
      return retval;
}

/*
 * Returns waiting task that should be serviced first or NULL if none exists
 */
static struct ext_wait_queue *wq_get_first_waiter(
            struct mqueue_inode_info *info, int sr)
{
      struct list_head *ptr;

      ptr = info->e_wait_q[sr].list.prev;
      if (ptr == &info->e_wait_q[sr].list)
            return NULL;
      return list_entry(ptr, struct ext_wait_queue, list);
}

/* Auxiliary functions to manipulate messages' list */
static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
{
      int k;

      k = info->attr.mq_curmsgs - 1;
      while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
            info->messages[k + 1] = info->messages[k];
            k--;
      }
      info->attr.mq_curmsgs++;
      info->qsize += ptr->m_ts;
      info->messages[k + 1] = ptr;
}

static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
{
      info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
      return info->messages[info->attr.mq_curmsgs];
}

static inline void set_cookie(struct sk_buff *skb, char code)
{
      ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
}

/*
 * The next function is only to split too long sys_mq_timedsend
 */
static void __do_notify(struct mqueue_inode_info *info)
{
      /* notification
       * invoked when there is registered process and there isn't process
       * waiting synchronously for message AND state of queue changed from
       * empty to not empty. Here we are sure that no one is waiting
       * synchronously. */
      if (info->notify_owner &&
          info->attr.mq_curmsgs == 1) {
            struct siginfo sig_i;
            switch (info->notify.sigev_notify) {
            case SIGEV_NONE:
                  break;
            case SIGEV_SIGNAL:
                  /* sends signal */

                  sig_i.si_signo = info->notify.sigev_signo;
                  sig_i.si_errno = 0;
                  sig_i.si_code = SI_MESGQ;
                  sig_i.si_value = info->notify.sigev_value;
                  sig_i.si_pid = task_pid_vnr(current);
                  sig_i.si_uid = current->uid;

                  kill_pid_info(info->notify.sigev_signo,
                              &sig_i, info->notify_owner);
                  break;
            case SIGEV_THREAD:
                  set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
                  netlink_sendskb(info->notify_sock, info->notify_cookie);
                  break;
            }
            /* after notification unregisters process */
            put_pid(info->notify_owner);
            info->notify_owner = NULL;
      }
      wake_up(&info->wait_q);
}

static long prepare_timeout(const struct timespec __user *u_arg)
{
      struct timespec ts, nowts;
      long timeout;

      if (u_arg) {
            if (unlikely(copy_from_user(&ts, u_arg,
                              sizeof(struct timespec))))
                  return -EFAULT;

            if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0
                  || ts.tv_nsec >= NSEC_PER_SEC))
                  return -EINVAL;
            nowts = CURRENT_TIME;
            /* first subtract as jiffies can't be too big */
            ts.tv_sec -= nowts.tv_sec;
            if (ts.tv_nsec < nowts.tv_nsec) {
                  ts.tv_nsec += NSEC_PER_SEC;
                  ts.tv_sec--;
            }
            ts.tv_nsec -= nowts.tv_nsec;
            if (ts.tv_sec < 0)
                  return 0;

            timeout = timespec_to_jiffies(&ts) + 1;
      } else
            return MAX_SCHEDULE_TIMEOUT;

      return timeout;
}

static void remove_notification(struct mqueue_inode_info *info)
{
      if (info->notify_owner != NULL &&
          info->notify.sigev_notify == SIGEV_THREAD) {
            set_cookie(info->notify_cookie, NOTIFY_REMOVED);
            netlink_sendskb(info->notify_sock, info->notify_cookie);
      }
      put_pid(info->notify_owner);
      info->notify_owner = NULL;
}

static int mq_attr_ok(struct mq_attr *attr)
{
      if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
            return 0;
      if (capable(CAP_SYS_RESOURCE)) {
            if (attr->mq_maxmsg > HARD_MSGMAX)
                  return 0;
      } else {
            if (attr->mq_maxmsg > msg_max ||
                        attr->mq_msgsize > msgsize_max)
                  return 0;
      }
      /* check for overflow */
      if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
            return 0;
      if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
          (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
          (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
            return 0;
      return 1;
}

/*
 * Invoked when creating a new queue via sys_mq_open
 */
static struct file *do_create(struct dentry *dir, struct dentry *dentry,
                  int oflag, mode_t mode, struct mq_attr __user *u_attr)
{
      struct mq_attr attr;
      int ret;

      if (u_attr) {
            ret = -EFAULT;
            if (copy_from_user(&attr, u_attr, sizeof(attr)))
                  goto out;
            ret = -EINVAL;
            if (!mq_attr_ok(&attr))
                  goto out;
            /* store for use during create */
            dentry->d_fsdata = &attr;
      }

      mode &= ~current->fs->umask;
      ret = vfs_create(dir->d_inode, dentry, mode, NULL);
      dentry->d_fsdata = NULL;
      if (ret)
            goto out;

      return dentry_open(dentry, mqueue_mnt, oflag);

out:
      dput(dentry);
      mntput(mqueue_mnt);
      return ERR_PTR(ret);
}

/* Opens existing queue */
static struct file *do_open(struct dentry *dentry, int oflag)
{
static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
                              MAY_READ | MAY_WRITE };

      if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
            dput(dentry);
            mntput(mqueue_mnt);
            return ERR_PTR(-EINVAL);
      }

      if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) {
            dput(dentry);
            mntput(mqueue_mnt);
            return ERR_PTR(-EACCES);
      }

      return dentry_open(dentry, mqueue_mnt, oflag);
}

asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
                        struct mq_attr __user *u_attr)
{
      struct dentry *dentry;
      struct file *filp;
      char *name;
      int fd, error;

      error = audit_mq_open(oflag, mode, u_attr);
      if (error != 0)
            return error;

      if (IS_ERR(name = getname(u_name)))
            return PTR_ERR(name);

      fd = get_unused_fd();
      if (fd < 0)
            goto out_putname;

      mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
      dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
      if (IS_ERR(dentry)) {
            error = PTR_ERR(dentry);
            goto out_err;
      }
      mntget(mqueue_mnt);

      if (oflag & O_CREAT) {
            if (dentry->d_inode) {  /* entry already exists */
                  audit_inode(name, dentry);
                  error = -EEXIST;
                  if (oflag & O_EXCL)
                        goto out;
                  filp = do_open(dentry, oflag);
            } else {
                  filp = do_create(mqueue_mnt->mnt_root, dentry,
                                    oflag, mode, u_attr);
            }
      } else {
            error = -ENOENT;
            if (!dentry->d_inode)
                  goto out;
            audit_inode(name, dentry);
            filp = do_open(dentry, oflag);
      }

      if (IS_ERR(filp)) {
            error = PTR_ERR(filp);
            goto out_putfd;
      }

      set_close_on_exec(fd, 1);
      fd_install(fd, filp);
      goto out_upsem;

out:
      dput(dentry);
      mntput(mqueue_mnt);
out_putfd:
      put_unused_fd(fd);
out_err:
      fd = error;
out_upsem:
      mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
out_putname:
      putname(name);
      return fd;
}

asmlinkage long sys_mq_unlink(const char __user *u_name)
{
      int err;
      char *name;
      struct dentry *dentry;
      struct inode *inode = NULL;

      name = getname(u_name);
      if (IS_ERR(name))
            return PTR_ERR(name);

      mutex_lock_nested(&mqueue_mnt->mnt_root->d_inode->i_mutex,
                  I_MUTEX_PARENT);
      dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
      if (IS_ERR(dentry)) {
            err = PTR_ERR(dentry);
            goto out_unlock;
      }

      if (!dentry->d_inode) {
            err = -ENOENT;
            goto out_err;
      }

      inode = dentry->d_inode;
      if (inode)
            atomic_inc(&inode->i_count);

      err = vfs_unlink(dentry->d_parent->d_inode, dentry);
out_err:
      dput(dentry);

out_unlock:
      mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
      putname(name);
      if (inode)
            iput(inode);

      return err;
}

/* Pipelined send and receive functions.
 *
 * If a receiver finds no waiting message, then it registers itself in the
 * list of waiting receivers. A sender checks that list before adding the new
 * message into the message array. If there is a waiting receiver, then it
 * bypasses the message array and directly hands the message over to the
 * receiver.
 * The receiver accepts the message and returns without grabbing the queue
 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
 * are necessary. The same algorithm is used for sysv semaphores, see
 * ipc/sem.c for more details.
 *
 * The same algorithm is used for senders.
 */

/* pipelined_send() - send a message directly to the task waiting in
 * sys_mq_timedreceive() (without inserting message into a queue).
 */
static inline void pipelined_send(struct mqueue_inode_info *info,
                          struct msg_msg *message,
                          struct ext_wait_queue *receiver)
{
      receiver->msg = message;
      list_del(&receiver->list);
      receiver->state = STATE_PENDING;
      wake_up_process(receiver->task);
      smp_wmb();
      receiver->state = STATE_READY;
}

/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
 * gets its message and put to the queue (we have one free place for sure). */
static inline void pipelined_receive(struct mqueue_inode_info *info)
{
      struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);

      if (!sender) {
            /* for poll */
            wake_up_interruptible(&info->wait_q);
            return;
      }
      msg_insert(sender->msg, info);
      list_del(&sender->list);
      sender->state = STATE_PENDING;
      wake_up_process(sender->task);
      smp_wmb();
      sender->state = STATE_READY;
}

asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
      size_t msg_len, unsigned int msg_prio,
      const struct timespec __user *u_abs_timeout)
{
      struct file *filp;
      struct inode *inode;
      struct ext_wait_queue wait;
      struct ext_wait_queue *receiver;
      struct msg_msg *msg_ptr;
      struct mqueue_inode_info *info;
      long timeout;
      int ret;

      ret = audit_mq_timedsend(mqdes, msg_len, msg_prio, u_abs_timeout);
      if (ret != 0)
            return ret;

      if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
            return -EINVAL;

      timeout = prepare_timeout(u_abs_timeout);

      ret = -EBADF;
      filp = fget(mqdes);
      if (unlikely(!filp))
            goto out;

      inode = filp->f_path.dentry->d_inode;
      if (unlikely(filp->f_op != &mqueue_file_operations))
            goto out_fput;
      info = MQUEUE_I(inode);
      audit_inode(NULL, filp->f_path.dentry);

      if (unlikely(!(filp->f_mode & FMODE_WRITE)))
            goto out_fput;

      if (unlikely(msg_len > info->attr.mq_msgsize)) {
            ret = -EMSGSIZE;
            goto out_fput;
      }

      /* First try to allocate memory, before doing anything with
       * existing queues. */
      msg_ptr = load_msg(u_msg_ptr, msg_len);
      if (IS_ERR(msg_ptr)) {
            ret = PTR_ERR(msg_ptr);
            goto out_fput;
      }
      msg_ptr->m_ts = msg_len;
      msg_ptr->m_type = msg_prio;

      spin_lock(&info->lock);

      if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
            if (filp->f_flags & O_NONBLOCK) {
                  spin_unlock(&info->lock);
                  ret = -EAGAIN;
            } else if (unlikely(timeout < 0)) {
                  spin_unlock(&info->lock);
                  ret = timeout;
            } else {
                  wait.task = current;
                  wait.msg = (void *) msg_ptr;
                  wait.state = STATE_NONE;
                  ret = wq_sleep(info, SEND, timeout, &wait);
            }
            if (ret < 0)
                  free_msg(msg_ptr);
      } else {
            receiver = wq_get_first_waiter(info, RECV);
            if (receiver) {
                  pipelined_send(info, msg_ptr, receiver);
            } else {
                  /* adds message to the queue */
                  msg_insert(msg_ptr, info);
                  __do_notify(info);
            }
            inode->i_atime = inode->i_mtime = inode->i_ctime =
                        CURRENT_TIME;
            spin_unlock(&info->lock);
            ret = 0;
      }
out_fput:
      fput(filp);
out:
      return ret;
}

asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
      size_t msg_len, unsigned int __user *u_msg_prio,
      const struct timespec __user *u_abs_timeout)
{
      long timeout;
      ssize_t ret;
      struct msg_msg *msg_ptr;
      struct file *filp;
      struct inode *inode;
      struct mqueue_inode_info *info;
      struct ext_wait_queue wait;

      ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout);
      if (ret != 0)
            return ret;

      timeout = prepare_timeout(u_abs_timeout);

      ret = -EBADF;
      filp = fget(mqdes);
      if (unlikely(!filp))
            goto out;

      inode = filp->f_path.dentry->d_inode;
      if (unlikely(filp->f_op != &mqueue_file_operations))
            goto out_fput;
      info = MQUEUE_I(inode);
      audit_inode(NULL, filp->f_path.dentry);

      if (unlikely(!(filp->f_mode & FMODE_READ)))
            goto out_fput;

      /* checks if buffer is big enough */
      if (unlikely(msg_len < info->attr.mq_msgsize)) {
            ret = -EMSGSIZE;
            goto out_fput;
      }

      spin_lock(&info->lock);
      if (info->attr.mq_curmsgs == 0) {
            if (filp->f_flags & O_NONBLOCK) {
                  spin_unlock(&info->lock);
                  ret = -EAGAIN;
                  msg_ptr = NULL;
            } else if (unlikely(timeout < 0)) {
                  spin_unlock(&info->lock);
                  ret = timeout;
                  msg_ptr = NULL;
            } else {
                  wait.task = current;
                  wait.state = STATE_NONE;
                  ret = wq_sleep(info, RECV, timeout, &wait);
                  msg_ptr = wait.msg;
            }
      } else {
            msg_ptr = msg_get(info);

            inode->i_atime = inode->i_mtime = inode->i_ctime =
                        CURRENT_TIME;

            /* There is now free space in queue. */
            pipelined_receive(info);
            spin_unlock(&info->lock);
            ret = 0;
      }
      if (ret == 0) {
            ret = msg_ptr->m_ts;

            if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
                  store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
                  ret = -EFAULT;
            }
            free_msg(msg_ptr);
      }
out_fput:
      fput(filp);
out:
      return ret;
}

/*
 * Notes: the case when user wants us to deregister (with NULL as pointer)
 * and he isn't currently owner of notification, will be silently discarded.
 * It isn't explicitly defined in the POSIX.
 */
asmlinkage long sys_mq_notify(mqd_t mqdes,
                        const struct sigevent __user *u_notification)
{
      int ret;
      struct file *filp;
      struct sock *sock;
      struct inode *inode;
      struct sigevent notification;
      struct mqueue_inode_info *info;
      struct sk_buff *nc;

      ret = audit_mq_notify(mqdes, u_notification);
      if (ret != 0)
            return ret;

      nc = NULL;
      sock = NULL;
      if (u_notification != NULL) {
            if (copy_from_user(&notification, u_notification,
                              sizeof(struct sigevent)))
                  return -EFAULT;

            if (unlikely(notification.sigev_notify != SIGEV_NONE &&
                       notification.sigev_notify != SIGEV_SIGNAL &&
                       notification.sigev_notify != SIGEV_THREAD))
                  return -EINVAL;
            if (notification.sigev_notify == SIGEV_SIGNAL &&
                  !valid_signal(notification.sigev_signo)) {
                  return -EINVAL;
            }
            if (notification.sigev_notify == SIGEV_THREAD) {
                  long timeo;

                  /* create the notify skb */
                  nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
                  ret = -ENOMEM;
                  if (!nc)
                        goto out;
                  ret = -EFAULT;
                  if (copy_from_user(nc->data,
                              notification.sigev_value.sival_ptr,
                              NOTIFY_COOKIE_LEN)) {
                        goto out;
                  }

                  /* TODO: add a header? */
                  skb_put(nc, NOTIFY_COOKIE_LEN);
                  /* and attach it to the socket */
retry:
                  filp = fget(notification.sigev_signo);
                  ret = -EBADF;
                  if (!filp)
                        goto out;
                  sock = netlink_getsockbyfilp(filp);
                  fput(filp);
                  if (IS_ERR(sock)) {
                        ret = PTR_ERR(sock);
                        sock = NULL;
                        goto out;
                  }

                  timeo = MAX_SCHEDULE_TIMEOUT;
                  ret = netlink_attachskb(sock, nc, 0, &timeo, NULL);
                  if (ret == 1)
                              goto retry;
                  if (ret) {
                        sock = NULL;
                        nc = NULL;
                        goto out;
                  }
            }
      }

      ret = -EBADF;
      filp = fget(mqdes);
      if (!filp)
            goto out;

      inode = filp->f_path.dentry->d_inode;
      if (unlikely(filp->f_op != &mqueue_file_operations))
            goto out_fput;
      info = MQUEUE_I(inode);

      ret = 0;
      spin_lock(&info->lock);
      if (u_notification == NULL) {
            if (info->notify_owner == task_tgid(current)) {
                  remove_notification(info);
                  inode->i_atime = inode->i_ctime = CURRENT_TIME;
            }
      } else if (info->notify_owner != NULL) {
            ret = -EBUSY;
      } else {
            switch (notification.sigev_notify) {
            case SIGEV_NONE:
                  info->notify.sigev_notify = SIGEV_NONE;
                  break;
            case SIGEV_THREAD:
                  info->notify_sock = sock;
                  info->notify_cookie = nc;
                  sock = NULL;
                  nc = NULL;
                  info->notify.sigev_notify = SIGEV_THREAD;
                  break;
            case SIGEV_SIGNAL:
                  info->notify.sigev_signo = notification.sigev_signo;
                  info->notify.sigev_value = notification.sigev_value;
                  info->notify.sigev_notify = SIGEV_SIGNAL;
                  break;
            }

            info->notify_owner = get_pid(task_tgid(current));
            inode->i_atime = inode->i_ctime = CURRENT_TIME;
      }
      spin_unlock(&info->lock);
out_fput:
      fput(filp);
out:
      if (sock) {
            netlink_detachskb(sock, nc);
      } else if (nc) {
            dev_kfree_skb(nc);
      }
      return ret;
}

asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
                  const struct mq_attr __user *u_mqstat,
                  struct mq_attr __user *u_omqstat)
{
      int ret;
      struct mq_attr mqstat, omqstat;
      struct file *filp;
      struct inode *inode;
      struct mqueue_inode_info *info;

      if (u_mqstat != NULL) {
            if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
                  return -EFAULT;
            if (mqstat.mq_flags & (~O_NONBLOCK))
                  return -EINVAL;
      }

      ret = -EBADF;
      filp = fget(mqdes);
      if (!filp)
            goto out;

      inode = filp->f_path.dentry->d_inode;
      if (unlikely(filp->f_op != &mqueue_file_operations))
            goto out_fput;
      info = MQUEUE_I(inode);

      spin_lock(&info->lock);

      omqstat = info->attr;
      omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
      if (u_mqstat) {
            ret = audit_mq_getsetattr(mqdes, &mqstat);
            if (ret != 0) {
                  spin_unlock(&info->lock);
                  goto out_fput;
            }
            if (mqstat.mq_flags & O_NONBLOCK)
                  filp->f_flags |= O_NONBLOCK;
            else
                  filp->f_flags &= ~O_NONBLOCK;

            inode->i_atime = inode->i_ctime = CURRENT_TIME;
      }

      spin_unlock(&info->lock);

      ret = 0;
      if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
                                    sizeof(struct mq_attr)))
            ret = -EFAULT;

out_fput:
      fput(filp);
out:
      return ret;
}

static const struct inode_operations mqueue_dir_inode_operations = {
      .lookup = simple_lookup,
      .create = mqueue_create,
      .unlink = mqueue_unlink,
};

static const struct file_operations mqueue_file_operations = {
      .flush = mqueue_flush_file,
      .poll = mqueue_poll_file,
      .read = mqueue_read_file,
};

static struct super_operations mqueue_super_ops = {
      .alloc_inode = mqueue_alloc_inode,
      .destroy_inode = mqueue_destroy_inode,
      .statfs = simple_statfs,
      .delete_inode = mqueue_delete_inode,
      .drop_inode = generic_delete_inode,
};

static struct file_system_type mqueue_fs_type = {
      .name = "mqueue",
      .get_sb = mqueue_get_sb,
      .kill_sb = kill_litter_super,
};

static int msg_max_limit_min = DFLT_MSGMAX;
static int msg_max_limit_max = HARD_MSGMAX;

static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX;
static int msg_maxsize_limit_max = INT_MAX;

static ctl_table mq_sysctls[] = {
      {
            .procname   = "queues_max",
            .data       = &queues_max,
            .maxlen           = sizeof(int),
            .mode       = 0644,
            .proc_handler     = &proc_dointvec,
      },
      {
            .procname   = "msg_max",
            .data       = &msg_max,
            .maxlen           = sizeof(int),
            .mode       = 0644,
            .proc_handler     = &proc_dointvec_minmax,
            .extra1           = &msg_max_limit_min,
            .extra2           = &msg_max_limit_max,
      },
      {
            .procname   = "msgsize_max",
            .data       = &msgsize_max,
            .maxlen           = sizeof(int),
            .mode       = 0644,
            .proc_handler     = &proc_dointvec_minmax,
            .extra1           = &msg_maxsize_limit_min,
            .extra2           = &msg_maxsize_limit_max,
      },
      { .ctl_name = 0 }
};

static ctl_table mq_sysctl_dir[] = {
      {
            .procname   = "mqueue",
            .mode       = 0555,
            .child            = mq_sysctls,
      },
      { .ctl_name = 0 }
};

static ctl_table mq_sysctl_root[] = {
      {
            .ctl_name   = CTL_FS,
            .procname   = "fs",
            .mode       = 0555,
            .child            = mq_sysctl_dir,
      },
      { .ctl_name = 0 }
};

static int __init init_mqueue_fs(void)
{
      int error;

      mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
                        sizeof(struct mqueue_inode_info), 0,
                        SLAB_HWCACHE_ALIGN, init_once);
      if (mqueue_inode_cachep == NULL)
            return -ENOMEM;

      /* ignore failues - they are not fatal */
      mq_sysctl_table = register_sysctl_table(mq_sysctl_root);

      error = register_filesystem(&mqueue_fs_type);
      if (error)
            goto out_sysctl;

      if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
            error = PTR_ERR(mqueue_mnt);
            goto out_filesystem;
      }

      /* internal initialization - not common for vfs */
      queues_count = 0;
      spin_lock_init(&mq_lock);

      return 0;

out_filesystem:
      unregister_filesystem(&mqueue_fs_type);
out_sysctl:
      if (mq_sysctl_table)
            unregister_sysctl_table(mq_sysctl_table);
      kmem_cache_destroy(mqueue_inode_cachep);
      return error;
}

__initcall(init_mqueue_fs);

Generated by  Doxygen 1.6.0   Back to index