ipc/mqueue.c

   1 /*
   2  * POSIX message queues filesystem for Linux.
   3  *
   4  * Copyright (C) 2003,2004  Krzysztof Benedyczak    (golbi@mat.uni.torun.pl)
   5  *                          Michal Wronski          (Michal.Wronski@motorola.com)
   6  *
   7  * Spinlocks:               Mohamed Abbas           (abbas.mohamed@intel.com)
   8  * Lockless receive & send, fd based notify:
   9  *                          Manfred Spraul          (manfred@colorfullife.com)
  10  *
  11  * This file is released under the GPL.
  12  */
  13
  14 #include <linux/capability.h>
  15 #include <linux/init.h>
  16 #include <linux/pagemap.h>
  17 #include <linux/file.h>
  18 #include <linux/mount.h>
  19 #include <linux/namei.h>
  20 #include <linux/sysctl.h>
  21 #include <linux/poll.h>
  22 #include <linux/mqueue.h>
  23 #include <linux/msg.h>
  24 #include <linux/skbuff.h>
  25 #include <linux/netlink.h>
  26 #include <linux/syscalls.h>
  27 #include <linux/signal.h>
  28 #include <net/sock.h>
  29 #include "util.h"
  30
  31 #define MQUEUE_MAGIC    0x19800202
  32 #define DIRENT_SIZE     20
  33 #define FILENT_SIZE     80
  34
  35 #define SEND            0
  36 #define RECV            1
  37
  38 #define STATE_NONE      0
  39 #define STATE_PENDING   1
  40 #define STATE_READY     2
  41
  42 /* used by sysctl */
  43 #define FS_MQUEUE       1
  44 #define CTL_QUEUESMAX   2
  45 #define CTL_MSGMAX      3
  46 #define CTL_MSGSIZEMAX  4
  47
  48 /* default values */
  49 #define DFLT_QUEUESMAX  256     /* max number of message queues */
  50 #define DFLT_MSGMAX     10      /* max number of messages in each queue */
  51 #define HARD_MSGMAX     (131072/sizeof(void*))
  52 #define DFLT_MSGSIZEMAX 8192    /* max message size */
  53
  54 #define NOTIFY_COOKIE_LEN       32
  55
  56 struct ext_wait_queue {         /* queue of sleeping tasks */
  57         struct task_struct *task;
  58         struct list_head list;
  59         struct msg_msg *msg;    /* ptr of loaded message */
  60         int state;              /* one of STATE_* values */
  61 };
  62
  63 struct mqueue_inode_info {
  64         spinlock_t lock;
  65         struct inode vfs_inode;
  66         wait_queue_head_t wait_q;
  67
  68         struct msg_msg **messages;
  69         struct mq_attr attr;
  70
  71         struct sigevent notify;
  72         pid_t notify_owner;
  73         struct user_struct *user;       /* user who created, for accounting */
  74         struct sock *notify_sock;
  75         struct sk_buff *notify_cookie;
  76
  77         /* for tasks waiting for free space and messages, respectively */
  78         struct ext_wait_queue e_wait_q[2];
  79
  80         unsigned long qsize; /* size of queue in memory (sum of all msgs) */
  81 };
  82
  83 static struct inode_operations mqueue_dir_inode_operations;
  84 static struct file_operations mqueue_file_operations;
  85 static struct super_operations mqueue_super_ops;
  86 static void remove_notification(struct mqueue_inode_info *info);
  87
  88 static spinlock_t mq_lock;
  89 static kmem_cache_t *mqueue_inode_cachep;
  90 static struct vfsmount *mqueue_mnt;
  91
  92 static unsigned int queues_count;
  93 static unsigned int queues_max  = DFLT_QUEUESMAX;
  94 static unsigned int msg_max     = DFLT_MSGMAX;
  95 static unsigned int msgsize_max = DFLT_MSGSIZEMAX;
  96
  97 static struct ctl_table_header * mq_sysctl_table;
  98
  99 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
 100 {
 101         return container_of(inode, struct mqueue_inode_info, vfs_inode);
 102 }
 103
 104 static struct inode *mqueue_get_inode(struct super_block *sb, int mode,
 105                                                         struct mq_attr *attr)
 106 {
 107         struct inode *inode;
 108
 109         inode = new_inode(sb);
 110         if (inode) {
 111                 inode->i_mode = mode;
 112                 inode->i_uid = current->fsuid;
 113                 inode->i_gid = current->fsgid;
 114                 inode->i_blksize = PAGE_CACHE_SIZE;
 115                 inode->i_blocks = 0;
 116                 inode->i_mtime = inode->i_ctime = inode->i_atime =
 117                                 CURRENT_TIME;
 118
 119                 if (S_ISREG(mode)) {
 120                         struct mqueue_inode_info *info;
 121                         struct task_struct *p = current;
 122                         struct user_struct *u = p->user;
 123                         unsigned long mq_bytes, mq_msg_tblsz;
 124
 125                         inode->i_fop = &mqueue_file_operations;
 126                         inode->i_size = FILENT_SIZE;
 127                         /* mqueue specific info */
 128                         info = MQUEUE_I(inode);
 129                         spin_lock_init(&info->lock);
 130                         init_waitqueue_head(&info->wait_q);
 131                         INIT_LIST_HEAD(&info->e_wait_q[0].list);
 132                         INIT_LIST_HEAD(&info->e_wait_q[1].list);
 133                         info->messages = NULL;
 134                         info->notify_owner = 0;
 135                         info->qsize = 0;
 136                         info->user = NULL;      /* set when all is ok */
 137                         memset(&info->attr, 0, sizeof(info->attr));
 138                         info->attr.mq_maxmsg = DFLT_MSGMAX;
 139                         info->attr.mq_msgsize = DFLT_MSGSIZEMAX;
 140                         if (attr) {
 141                                 info->attr.mq_maxmsg = attr->mq_maxmsg;
 142                                 info->attr.mq_msgsize = attr->mq_msgsize;
 143                         }
 144                         mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
 145                         mq_bytes = (mq_msg_tblsz +
 146                                 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
 147
 148                         spin_lock(&mq_lock);
 149                         if (u->mq_bytes + mq_bytes < u->mq_bytes ||
 150                             u->mq_bytes + mq_bytes >
 151                             p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
 152                                 spin_unlock(&mq_lock);
 153                                 goto out_inode;
 154                         }
 155                         u->mq_bytes += mq_bytes;
 156                         spin_unlock(&mq_lock);
 157
 158                         info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
 159                         if (!info->messages) {
 160                                 spin_lock(&mq_lock);
 161                                 u->mq_bytes -= mq_bytes;
 162                                 spin_unlock(&mq_lock);
 163                                 goto out_inode;
 164                         }
 165                         /* all is ok */
 166                         info->user = get_uid(u);
 167                 } else if (S_ISDIR(mode)) {
 168                         inode->i_nlink++;
 169                         /* Some things misbehave if size == 0 on a directory */
 170                         inode->i_size = 2 * DIRENT_SIZE;
 171                         inode->i_op = &mqueue_dir_inode_operations;
 172                         inode->i_fop = &simple_dir_operations;
 173                 }
 174         }
 175         return inode;
 176 out_inode:
 177         make_bad_inode(inode);
 178         iput(inode);
 179         return NULL;
 180 }
 181
 182 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
 183 {
 184         struct inode *inode;
 185
 186         sb->s_blocksize = PAGE_CACHE_SIZE;
 187         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 188         sb->s_magic = MQUEUE_MAGIC;
 189         sb->s_op = &mqueue_super_ops;
 190
 191         inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
 192         if (!inode)
 193                 return -ENOMEM;
 194
 195         sb->s_root = d_alloc_root(inode);
 196         if (!sb->s_root) {
 197                 iput(inode);
 198                 return -ENOMEM;
 199         }
 200
 201         return 0;
 202 }
 203
 204 static struct super_block *mqueue_get_sb(struct file_system_type *fs_type,
 205                                          int flags, const char *dev_name,
 206                                          void *data)
 207 {
 208         return get_sb_single(fs_type, flags, data, mqueue_fill_super);
 209 }
 210
 211 static void init_once(void *foo, kmem_cache_t * cachep, unsigned long flags)
 212 {
 213         struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
 214
 215         if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) ==
 216                 SLAB_CTOR_CONSTRUCTOR)
 217                 inode_init_once(&p->vfs_inode);
 218 }
 219
 220 static struct inode *mqueue_alloc_inode(struct super_block *sb)
 221 {
 222         struct mqueue_inode_info *ei;
 223
 224         ei = kmem_cache_alloc(mqueue_inode_cachep, SLAB_KERNEL);
 225         if (!ei)
 226                 return NULL;
 227         return &ei->vfs_inode;
 228 }
 229
 230 static void mqueue_destroy_inode(struct inode *inode)
 231 {
 232         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
 233 }
 234
 235 static void mqueue_delete_inode(struct inode *inode)
 236 {
 237         struct mqueue_inode_info *info;
 238         struct user_struct *user;
 239         unsigned long mq_bytes;
 240         int i;
 241
 242         if (S_ISDIR(inode->i_mode)) {
 243                 clear_inode(inode);
 244                 return;
 245         }
 246         info = MQUEUE_I(inode);
 247         spin_lock(&info->lock);
 248         for (i = 0; i < info->attr.mq_curmsgs; i++)
 249                 free_msg(info->messages[i]);
 250         kfree(info->messages);
 251         spin_unlock(&info->lock);
 252
 253         clear_inode(inode);
 254
 255         mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
 256                    (info->attr.mq_maxmsg * info->attr.mq_msgsize));
 257         user = info->user;
 258         if (user) {
 259                 spin_lock(&mq_lock);
 260                 user->mq_bytes -= mq_bytes;
 261                 queues_count--;
 262                 spin_unlock(&mq_lock);
 263                 free_uid(user);
 264         }
 265 }
 266
 267 static int mqueue_create(struct inode *dir, struct dentry *dentry,
 268                                 int mode, struct nameidata *nd)
 269 {
 270         struct inode *inode;
 271         struct mq_attr *attr = dentry->d_fsdata;
 272         int error;
 273
 274         spin_lock(&mq_lock);
 275         if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
 276                 error = -ENOSPC;
 277                 goto out_lock;
 278         }
 279         queues_count++;
 280         spin_unlock(&mq_lock);
 281
 282         inode = mqueue_get_inode(dir->i_sb, mode, attr);
 283         if (!inode) {
 284                 error = -ENOMEM;
 285                 spin_lock(&mq_lock);
 286                 queues_count--;
 287                 goto out_lock;
 288         }
 289
 290         dir->i_size += DIRENT_SIZE;
 291         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 292
 293         d_instantiate(dentry, inode);
 294         dget(dentry);
 295         return 0;
 296 out_lock:
 297         spin_unlock(&mq_lock);
 298         return error;
 299 }
 300
 301 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
 302 {
 303         struct inode *inode = dentry->d_inode;
 304
 305         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 306         dir->i_size -= DIRENT_SIZE;
 307         inode->i_nlink--;
 308         dput(dentry);
 309         return 0;
 310 }
 311
 312 /*
 313 *       This is routine for system read from queue file.
 314 *       To avoid mess with doing here some sort of mq_receive we allow
 315 *       to read only queue size & notification info (the only values
 316 *       that are interesting from user point of view and aren't accessible
 317 *       through std routines)
 318 */
 319 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
 320                                 size_t count, loff_t * off)
 321 {
 322         struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
 323         char buffer[FILENT_SIZE];
 324         size_t slen;
 325         loff_t o;
 326
 327         if (!count)
 328                 return 0;
 329
 330         spin_lock(&info->lock);
 331         snprintf(buffer, sizeof(buffer),
 332                         "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
 333                         info->qsize,
 334                         info->notify_owner ? info->notify.sigev_notify : 0,
 335                         (info->notify_owner &&
 336                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
 337                                 info->notify.sigev_signo : 0,
 338                         info->notify_owner);
 339         spin_unlock(&info->lock);
 340         buffer[sizeof(buffer)-1] = '\0';
 341         slen = strlen(buffer)+1;
 342
 343         o = *off;
 344         if (o > slen)
 345                 return 0;
 346
 347         if (o + count > slen)
 348                 count = slen - o;
 349
 350         if (copy_to_user(u_data, buffer + o, count))
 351                 return -EFAULT;
 352
 353         *off = o + count;
 354         filp->f_dentry->d_inode->i_atime = filp->f_dentry->d_inode->i_ctime = CURRENT_TIME;
 355         return count;
 356 }
 357
 358 static int mqueue_flush_file(struct file *filp)
 359 {
 360         struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
 361
 362         spin_lock(&info->lock);
 363         if (current->tgid == info->notify_owner)
 364                 remove_notification(info);
 365
 366         spin_unlock(&info->lock);
 367         return 0;
 368 }
 369
 370 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
 371 {
 372         struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
 373         int retval = 0;
 374
 375         poll_wait(filp, &info->wait_q, poll_tab);
 376
 377         spin_lock(&info->lock);
 378         if (info->attr.mq_curmsgs)
 379                 retval = POLLIN | POLLRDNORM;
 380
 381         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
 382                 retval |= POLLOUT | POLLWRNORM;
 383         spin_unlock(&info->lock);
 384
 385         return retval;
 386 }
 387
 388 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
 389 static void wq_add(struct mqueue_inode_info *info, int sr,
 390                         struct ext_wait_queue *ewp)
 391 {
 392         struct ext_wait_queue *walk;
 393
 394         ewp->task = current;
 395
 396         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
 397                 if (walk->task->static_prio <= current->static_prio) {
 398                         list_add_tail(&ewp->list, &walk->list);
 399                         return;
 400                 }
 401         }
 402         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
 403 }
 404
 405 /*
 406  * Puts current task to sleep. Caller must hold queue lock. After return
 407  * lock isn't held.
 408  * sr: SEND or RECV
 409  */
 410 static int wq_sleep(struct mqueue_inode_info *info, int sr,
 411                         long timeout, struct ext_wait_queue *ewp)
 412 {
 413         int retval;
 414         signed long time;
 415
 416         wq_add(info, sr, ewp);
 417
 418         for (;;) {
 419                 set_current_state(TASK_INTERRUPTIBLE);
 420
 421                 spin_unlock(&info->lock);
 422                 time = schedule_timeout(timeout);
 423
 424                 while (ewp->state == STATE_PENDING)
 425                         cpu_relax();
 426
 427                 if (ewp->state == STATE_READY) {
 428                         retval = 0;
 429                         goto out;
 430                 }
 431                 spin_lock(&info->lock);
 432                 if (ewp->state == STATE_READY) {
 433                         retval = 0;
 434                         goto out_unlock;
 435                 }
 436                 if (signal_pending(current)) {
 437                         retval = -ERESTARTSYS;
 438                         break;
 439                 }
 440                 if (time == 0) {
 441                         retval = -ETIMEDOUT;
 442                         break;
 443                 }
 444         }
 445         list_del(&ewp->list);
 446 out_unlock:
 447         spin_unlock(&info->lock);
 448 out:
 449         return retval;
 450 }
 451
 452 /*
 453  * Returns waiting task that should be serviced first or NULL if none exists
 454  */
 455 static struct ext_wait_queue *wq_get_first_waiter(
 456                 struct mqueue_inode_info *info, int sr)
 457 {
 458         struct list_head *ptr;
 459
 460         ptr = info->e_wait_q[sr].list.prev;
 461         if (ptr == &info->e_wait_q[sr].list)
 462                 return NULL;
 463         return list_entry(ptr, struct ext_wait_queue, list);
 464 }
 465
 466 /* Auxiliary functions to manipulate messages' list */
 467 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
 468 {
 469         int k;
 470
 471         k = info->attr.mq_curmsgs - 1;
 472         while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
 473                 info->messages[k + 1] = info->messages[k];
 474                 k--;
 475         }
 476         info->attr.mq_curmsgs++;
 477         info->qsize += ptr->m_ts;
 478         info->messages[k + 1] = ptr;
 479 }
 480
 481 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
 482 {
 483         info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
 484         return info->messages[info->attr.mq_curmsgs];
 485 }
 486
 487 static inline void set_cookie(struct sk_buff *skb, char code)
 488 {
 489         ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
 490 }
 491
 492 /*
 493  * The next function is only to split too long sys_mq_timedsend
 494  */
 495 static void __do_notify(struct mqueue_inode_info *info)
 496 {
 497         /* notification
 498          * invoked when there is registered process and there isn't process
 499          * waiting synchronously for message AND state of queue changed from
 500          * empty to not empty. Here we are sure that no one is waiting
 501          * synchronously. */
 502         if (info->notify_owner &&
 503             info->attr.mq_curmsgs == 1) {
 504                 struct siginfo sig_i;
 505                 switch (info->notify.sigev_notify) {
 506                 case SIGEV_NONE:
 507                         break;
 508                 case SIGEV_SIGNAL:
 509                         /* sends signal */
 510
 511                         sig_i.si_signo = info->notify.sigev_signo;
 512                         sig_i.si_errno = 0;
 513                         sig_i.si_code = SI_MESGQ;
 514                         sig_i.si_value = info->notify.sigev_value;
 515                         sig_i.si_pid = current->tgid;
 516                         sig_i.si_uid = current->uid;
 517
 518                         kill_proc_info(info->notify.sigev_signo,
 519                                        &sig_i, info->notify_owner);
 520                         break;
 521                 case SIGEV_THREAD:
 522                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
 523                         netlink_sendskb(info->notify_sock,
 524                                         info->notify_cookie, 0);
 525                         break;
 526                 }
 527                 /* after notification unregisters process */
 528                 info->notify_owner = 0;
 529         }
 530         wake_up(&info->wait_q);
 531 }
 532
 533 static long prepare_timeout(const struct timespec __user *u_arg)
 534 {
 535         struct timespec ts, nowts;
 536         long timeout;
 537
 538         if (u_arg) {
 539                 if (unlikely(copy_from_user(&ts, u_arg,
 540                                         sizeof(struct timespec))))
 541                         return -EFAULT;
 542
 543                 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0
 544                         || ts.tv_nsec >= NSEC_PER_SEC))
 545                         return -EINVAL;
 546                 nowts = CURRENT_TIME;
 547                 /* first subtract as jiffies can't be too big */
 548                 ts.tv_sec -= nowts.tv_sec;
 549                 if (ts.tv_nsec < nowts.tv_nsec) {
 550                         ts.tv_nsec += NSEC_PER_SEC;
 551                         ts.tv_sec--;
 552                 }
 553                 ts.tv_nsec -= nowts.tv_nsec;
 554                 if (ts.tv_sec < 0)
 555                         return 0;
 556
 557                 timeout = timespec_to_jiffies(&ts) + 1;
 558         } else
 559                 return MAX_SCHEDULE_TIMEOUT;
 560
 561         return timeout;
 562 }
 563
 564 static void remove_notification(struct mqueue_inode_info *info)
 565 {
 566         if (info->notify_owner != 0 &&
 567             info->notify.sigev_notify == SIGEV_THREAD) {
 568                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
 569                 netlink_sendskb(info->notify_sock, info->notify_cookie, 0);
 570         }
 571         info->notify_owner = 0;
 572 }
 573
 574 static int mq_attr_ok(struct mq_attr *attr)
 575 {
 576         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
 577                 return 0;
 578         if (capable(CAP_SYS_RESOURCE)) {
 579                 if (attr->mq_maxmsg > HARD_MSGMAX)
 580                         return 0;
 581         } else {
 582                 if (attr->mq_maxmsg > msg_max ||
 583                                 attr->mq_msgsize > msgsize_max)
 584                         return 0;
 585         }
 586         /* check for overflow */
 587         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
 588                 return 0;
 589         if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
 590             (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
 591             (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
 592                 return 0;
 593         return 1;
 594 }
 595
 596 /*
 597  * Invoked when creating a new queue via sys_mq_open
 598  */
 599 static struct file *do_create(struct dentry *dir, struct dentry *dentry,
 600                         int oflag, mode_t mode, struct mq_attr __user *u_attr)
 601 {
 602         struct mq_attr attr;
 603         int ret;
 604
 605         if (u_attr) {
 606                 ret = -EFAULT;
 607                 if (copy_from_user(&attr, u_attr, sizeof(attr)))
 608                         goto out;
 609                 ret = -EINVAL;
 610                 if (!mq_attr_ok(&attr))
 611                         goto out;
 612                 /* store for use during create */
 613                 dentry->d_fsdata = &attr;
 614         }
 615
 616         mode &= ~current->fs->umask;
 617         ret = vfs_create(dir->d_inode, dentry, mode, NULL);
 618         dentry->d_fsdata = NULL;
 619         if (ret)
 620                 goto out;
 621
 622         return dentry_open(dentry, mqueue_mnt, oflag);
 623
 624 out:
 625         dput(dentry);
 626         mntput(mqueue_mnt);
 627         return ERR_PTR(ret);
 628 }
 629
 630 /* Opens existing queue */
 631 static struct file *do_open(struct dentry *dentry, int oflag)
 632 {
 633 static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
 634                                         MAY_READ | MAY_WRITE };
 635
 636         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
 637                 dput(dentry);
 638                 mntput(mqueue_mnt);
 639                 return ERR_PTR(-EINVAL);
 640         }
 641
 642         if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) {
 643                 dput(dentry);
 644                 mntput(mqueue_mnt);
 645                 return ERR_PTR(-EACCES);
 646         }
 647
 648         return dentry_open(dentry, mqueue_mnt, oflag);
 649 }
 650
 651 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
 652                                 struct mq_attr __user *u_attr)
 653 {
 654         struct dentry *dentry;
 655         struct file *filp;
 656         char *name;
 657         int fd, error;
 658
 659         if (IS_ERR(name = getname(u_name)))
 660                 return PTR_ERR(name);
 661
 662         fd = get_unused_fd();
 663         if (fd < 0)
 664                 goto out_putname;
 665
 666         mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
 667         dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
 668         if (IS_ERR(dentry)) {
 669                 error = PTR_ERR(dentry);
 670                 goto out_err;
 671         }
 672         mntget(mqueue_mnt);
 673
 674         if (oflag & O_CREAT) {
 675                 if (dentry->d_inode) {  /* entry already exists */
 676                         error = -EEXIST;
 677                         if (oflag & O_EXCL)
 678                                 goto out;
 679                         filp = do_open(dentry, oflag);
 680                 } else {
 681                         filp = do_create(mqueue_mnt->mnt_root, dentry,
 682                                                 oflag, mode, u_attr);
 683                 }
 684         } else {
 685                 error = -ENOENT;
 686                 if (!dentry->d_inode)
 687                         goto out;
 688                 filp = do_open(dentry, oflag);
 689         }
 690
 691         if (IS_ERR(filp)) {
 692                 error = PTR_ERR(filp);
 693                 goto out_putfd;
 694         }
 695
 696         set_close_on_exec(fd, 1);
 697         fd_install(fd, filp);
 698         goto out_upsem;
 699
 700 out:
 701         dput(dentry);
 702         mntput(mqueue_mnt);
 703 out_putfd:
 704         put_unused_fd(fd);
 705 out_err:
 706         fd = error;
 707 out_upsem:
 708         mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
 709 out_putname:
 710         putname(name);
 711         return fd;
 712 }
 713
 714 asmlinkage long sys_mq_unlink(const char __user *u_name)
 715 {
 716         int err;
 717         char *name;
 718         struct dentry *dentry;
 719         struct inode *inode = NULL;
 720
 721         name = getname(u_name);
 722         if (IS_ERR(name))
 723                 return PTR_ERR(name);
 724
 725         mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
 726         dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
 727         if (IS_ERR(dentry)) {
 728                 err = PTR_ERR(dentry);
 729                 goto out_unlock;
 730         }
 731
 732         if (!dentry->d_inode) {
 733                 err = -ENOENT;
 734                 goto out_err;
 735         }
 736
 737         inode = dentry->d_inode;
 738         if (inode)
 739                 atomic_inc(&inode->i_count);
 740
 741         err = vfs_unlink(dentry->d_parent->d_inode, dentry);
 742 out_err:
 743         dput(dentry);
 744
 745 out_unlock:
 746         mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
 747         putname(name);
 748         if (inode)
 749                 iput(inode);
 750
 751         return err;
 752 }
 753
 754 /* Pipelined send and receive functions.
 755  *
 756  * If a receiver finds no waiting message, then it registers itself in the
 757  * list of waiting receivers. A sender checks that list before adding the new
 758  * message into the message array. If there is a waiting receiver, then it
 759  * bypasses the message array and directly hands the message over to the
 760  * receiver.
 761  * The receiver accepts the message and returns without grabbing the queue
 762  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
 763  * are necessary. The same algorithm is used for sysv semaphores, see
 764  * ipc/sem.c fore more details.
 765  *
 766  * The same algorithm is used for senders.
 767  */
 768
 769 /* pipelined_send() - send a message directly to the task waiting in
 770  * sys_mq_timedreceive() (without inserting message into a queue).
 771  */
 772 static inline void pipelined_send(struct mqueue_inode_info *info,
 773                                   struct msg_msg *message,
 774                                   struct ext_wait_queue *receiver)
 775 {
 776         receiver->msg = message;
 777         list_del(&receiver->list);
 778         receiver->state = STATE_PENDING;
 779         wake_up_process(receiver->task);
 780         smp_wmb();
 781         receiver->state = STATE_READY;
 782 }
 783
 784 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
 785  * gets its message and put to the queue (we have one free place for sure). */
 786 static inline void pipelined_receive(struct mqueue_inode_info *info)
 787 {
 788         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
 789
 790         if (!sender) {
 791                 /* for poll */
 792                 wake_up_interruptible(&info->wait_q);
 793                 return;
 794         }
 795         msg_insert(sender->msg, info);
 796         list_del(&sender->list);
 797         sender->state = STATE_PENDING;
 798         wake_up_process(sender->task);
 799         smp_wmb();
 800         sender->state = STATE_READY;
 801 }
 802
 803 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
 804         size_t msg_len, unsigned int msg_prio,
 805         const struct timespec __user *u_abs_timeout)
 806 {
 807         struct file *filp;
 808         struct inode *inode;
 809         struct ext_wait_queue wait;
 810         struct ext_wait_queue *receiver;
 811         struct msg_msg *msg_ptr;
 812         struct mqueue_inode_info *info;
 813         long timeout;
 814         int ret;
 815
 816         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
 817                 return -EINVAL;
 818
 819         timeout = prepare_timeout(u_abs_timeout);
 820
 821         ret = -EBADF;
 822         filp = fget(mqdes);
 823         if (unlikely(!filp))
 824                 goto out;
 825
 826         inode = filp->f_dentry->d_inode;
 827         if (unlikely(filp->f_op != &mqueue_file_operations))
 828                 goto out_fput;
 829         info = MQUEUE_I(inode);
 830
 831         if (unlikely(!(filp->f_mode & FMODE_WRITE)))
 832                 goto out_fput;
 833
 834         if (unlikely(msg_len > info->attr.mq_msgsize)) {
 835                 ret = -EMSGSIZE;
 836                 goto out_fput;
 837         }
 838
 839         /* First try to allocate memory, before doing anything with
 840          * existing queues. */
 841         msg_ptr = load_msg(u_msg_ptr, msg_len);
 842         if (IS_ERR(msg_ptr)) {
 843                 ret = PTR_ERR(msg_ptr);
 844                 goto out_fput;
 845         }
 846         msg_ptr->m_ts = msg_len;
 847         msg_ptr->m_type = msg_prio;
 848
 849         spin_lock(&info->lock);
 850
 851         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
 852                 if (filp->f_flags & O_NONBLOCK) {
 853                         spin_unlock(&info->lock);
 854                         ret = -EAGAIN;
 855                 } else if (unlikely(timeout < 0)) {
 856                         spin_unlock(&info->lock);
 857                         ret = timeout;
 858                 } else {
 859                         wait.task = current;
 860                         wait.msg = (void *) msg_ptr;
 861                         wait.state = STATE_NONE;
 862                         ret = wq_sleep(info, SEND, timeout, &wait);
 863                 }
 864                 if (ret < 0)
 865                         free_msg(msg_ptr);
 866         } else {
 867                 receiver = wq_get_first_waiter(info, RECV);
 868                 if (receiver) {
 869                         pipelined_send(info, msg_ptr, receiver);
 870                 } else {
 871                         /* adds message to the queue */
 872                         msg_insert(msg_ptr, info);
 873                         __do_notify(info);
 874                 }
 875                 inode->i_atime = inode->i_mtime = inode->i_ctime =
 876                                 CURRENT_TIME;
 877                 spin_unlock(&info->lock);
 878                 ret = 0;
 879         }
 880 out_fput:
 881         fput(filp);
 882 out:
 883         return ret;
 884 }
 885
 886 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
 887         size_t msg_len, unsigned int __user *u_msg_prio,
 888         const struct timespec __user *u_abs_timeout)
 889 {
 890         long timeout;
 891         ssize_t ret;
 892         struct msg_msg *msg_ptr;
 893         struct file *filp;
 894         struct inode *inode;
 895         struct mqueue_inode_info *info;
 896         struct ext_wait_queue wait;
 897
 898         timeout = prepare_timeout(u_abs_timeout);
 899
 900         ret = -EBADF;
 901         filp = fget(mqdes);
 902         if (unlikely(!filp))
 903                 goto out;
 904
 905         inode = filp->f_dentry->d_inode;
 906         if (unlikely(filp->f_op != &mqueue_file_operations))
 907                 goto out_fput;
 908         info = MQUEUE_I(inode);
 909
 910         if (unlikely(!(filp->f_mode & FMODE_READ)))
 911                 goto out_fput;
 912
 913         /* checks if buffer is big enough */
 914         if (unlikely(msg_len < info->attr.mq_msgsize)) {
 915                 ret = -EMSGSIZE;
 916                 goto out_fput;
 917         }
 918
 919         spin_lock(&info->lock);
 920         if (info->attr.mq_curmsgs == 0) {
 921                 if (filp->f_flags & O_NONBLOCK) {
 922                         spin_unlock(&info->lock);
 923                         ret = -EAGAIN;
 924                         msg_ptr = NULL;
 925                 } else if (unlikely(timeout < 0)) {
 926                         spin_unlock(&info->lock);
 927                         ret = timeout;
 928                         msg_ptr = NULL;
 929                 } else {
 930                         wait.task = current;
 931                         wait.state = STATE_NONE;
 932                         ret = wq_sleep(info, RECV, timeout, &wait);
 933                         msg_ptr = wait.msg;
 934                 }
 935         } else {
 936                 msg_ptr = msg_get(info);
 937
 938                 inode->i_atime = inode->i_mtime = inode->i_ctime =
 939                                 CURRENT_TIME;
 940
 941                 /* There is now free space in queue. */
 942                 pipelined_receive(info);
 943                 spin_unlock(&info->lock);
 944                 ret = 0;
 945         }
 946         if (ret == 0) {
 947                 ret = msg_ptr->m_ts;
 948
 949                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
 950                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
 951                         ret = -EFAULT;
 952                 }
 953                 free_msg(msg_ptr);
 954         }
 955 out_fput:
 956         fput(filp);
 957 out:
 958         return ret;
 959 }
 960
 961 /*
 962  * Notes: the case when user wants us to deregister (with NULL as pointer)
 963  * and he isn't currently owner of notification, will be silently discarded.
 964  * It isn't explicitly defined in the POSIX.
 965  */
 966 asmlinkage long sys_mq_notify(mqd_t mqdes,
 967                                 const struct sigevent __user *u_notification)
 968 {
 969         int ret;
 970         struct file *filp;
 971         struct sock *sock;
 972         struct inode *inode;
 973         struct sigevent notification;
 974         struct mqueue_inode_info *info;
 975         struct sk_buff *nc;
 976
 977         nc = NULL;
 978         sock = NULL;
 979         if (u_notification != NULL) {
 980                 if (copy_from_user(&notification, u_notification,
 981                                         sizeof(struct sigevent)))
 982                         return -EFAULT;
 983
 984                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
 985                              notification.sigev_notify != SIGEV_SIGNAL &&
 986                              notification.sigev_notify != SIGEV_THREAD))
 987                         return -EINVAL;
 988                 if (notification.sigev_notify == SIGEV_SIGNAL &&
 989                         !valid_signal(notification.sigev_signo)) {
 990                         return -EINVAL;
 991                 }
 992                 if (notification.sigev_notify == SIGEV_THREAD) {
 993                         /* create the notify skb */
 994                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
 995                         ret = -ENOMEM;
 996                         if (!nc)
 997                                 goto out;
 998                         ret = -EFAULT;
 999                         if (copy_from_user(nc->data,
1000                                         notification.sigev_value.sival_ptr,
1001                                         NOTIFY_COOKIE_LEN)) {
1002                                 goto out;
1003                         }
1004
1005                         /* TODO: add a header? */
1006                         skb_put(nc, NOTIFY_COOKIE_LEN);
1007                         /* and attach it to the socket */
1008 retry:
1009                         filp = fget(notification.sigev_signo);
1010                         ret = -EBADF;
1011                         if (!filp)
1012                                 goto out;
1013                         sock = netlink_getsockbyfilp(filp);
1014                         fput(filp);
1015                         if (IS_ERR(sock)) {
1016                                 ret = PTR_ERR(sock);
1017                                 sock = NULL;
1018                                 goto out;
1019                         }
1020
1021                         ret = netlink_attachskb(sock, nc, 0,
1022                                         MAX_SCHEDULE_TIMEOUT, NULL);
1023                         if (ret == 1)
1024                                 goto retry;
1025                         if (ret) {
1026                                 sock = NULL;
1027                                 nc = NULL;
1028                                 goto out;
1029                         }
1030                 }
1031         }
1032
1033         ret = -EBADF;
1034         filp = fget(mqdes);
1035         if (!filp)
1036                 goto out;
1037
1038         inode = filp->f_dentry->d_inode;
1039         if (unlikely(filp->f_op != &mqueue_file_operations))
1040                 goto out_fput;
1041         info = MQUEUE_I(inode);
1042
1043         ret = 0;
1044         spin_lock(&info->lock);
1045         if (u_notification == NULL) {
1046                 if (info->notify_owner == current->tgid) {
1047                         remove_notification(info);
1048                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1049                 }
1050         } else if (info->notify_owner != 0) {
1051                 ret = -EBUSY;
1052         } else {
1053                 switch (notification.sigev_notify) {
1054                 case SIGEV_NONE:
1055                         info->notify.sigev_notify = SIGEV_NONE;
1056                         break;
1057                 case SIGEV_THREAD:
1058                         info->notify_sock = sock;
1059                         info->notify_cookie = nc;
1060                         sock = NULL;
1061                         nc = NULL;
1062                         info->notify.sigev_notify = SIGEV_THREAD;
1063                         break;
1064                 case SIGEV_SIGNAL:
1065                         info->notify.sigev_signo = notification.sigev_signo;
1066                         info->notify.sigev_value = notification.sigev_value;
1067                         info->notify.sigev_notify = SIGEV_SIGNAL;
1068                         break;
1069                 }
1070                 info->notify_owner = current->tgid;
1071                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1072         }
1073         spin_unlock(&info->lock);
1074 out_fput:
1075         fput(filp);
1076 out:
1077         if (sock) {
1078                 netlink_detachskb(sock, nc);
1079         } else if (nc) {
1080                 dev_kfree_skb(nc);
1081         }
1082         return ret;
1083 }
1084
1085 asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1086                         const struct mq_attr __user *u_mqstat,
1087                         struct mq_attr __user *u_omqstat)
1088 {
1089         int ret;
1090         struct mq_attr mqstat, omqstat;
1091         struct file *filp;
1092         struct inode *inode;
1093         struct mqueue_inode_info *info;
1094
1095         if (u_mqstat != NULL) {
1096                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1097                         return -EFAULT;
1098                 if (mqstat.mq_flags & (~O_NONBLOCK))
1099                         return -EINVAL;
1100         }
1101
1102         ret = -EBADF;
1103         filp = fget(mqdes);
1104         if (!filp)
1105                 goto out;
1106
1107         inode = filp->f_dentry->d_inode;
1108         if (unlikely(filp->f_op != &mqueue_file_operations))
1109                 goto out_fput;
1110         info = MQUEUE_I(inode);
1111
1112         spin_lock(&info->lock);
1113
1114         omqstat = info->attr;
1115         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1116         if (u_mqstat) {
1117                 if (mqstat.mq_flags & O_NONBLOCK)
1118                         filp->f_flags |= O_NONBLOCK;
1119                 else
1120                         filp->f_flags &= ~O_NONBLOCK;
1121
1122                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1123         }
1124
1125         spin_unlock(&info->lock);
1126
1127         ret = 0;
1128         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1129                                                 sizeof(struct mq_attr)))
1130                 ret = -EFAULT;
1131
1132 out_fput:
1133         fput(filp);
1134 out:
1135         return ret;
1136 }
1137
1138 static struct inode_operations mqueue_dir_inode_operations = {
1139         .lookup = simple_lookup,
1140         .create = mqueue_create,
1141         .unlink = mqueue_unlink,
1142 };
1143
1144 static struct file_operations mqueue_file_operations = {
1145         .flush = mqueue_flush_file,
1146         .poll = mqueue_poll_file,
1147         .read = mqueue_read_file,
1148 };
1149
1150 static struct super_operations mqueue_super_ops = {
1151         .alloc_inode = mqueue_alloc_inode,
1152         .destroy_inode = mqueue_destroy_inode,
1153         .statfs = simple_statfs,
1154         .delete_inode = mqueue_delete_inode,
1155         .drop_inode = generic_delete_inode,
1156 };
1157
1158 static struct file_system_type mqueue_fs_type = {
1159         .name = "mqueue",
1160         .get_sb = mqueue_get_sb,
1161         .kill_sb = kill_litter_super,
1162 };
1163
1164 static int msg_max_limit_min = DFLT_MSGMAX;
1165 static int msg_max_limit_max = HARD_MSGMAX;
1166
1167 static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX;
1168 static int msg_maxsize_limit_max = INT_MAX;
1169
1170 static ctl_table mq_sysctls[] = {
1171         {
1172                 .ctl_name       = CTL_QUEUESMAX,
1173                 .procname       = "queues_max",
1174                 .data           = &queues_max,
1175                 .maxlen         = sizeof(int),
1176                 .mode           = 0644,
1177                 .proc_handler   = &proc_dointvec,
1178         },
1179         {
1180                 .ctl_name       = CTL_MSGMAX,
1181                 .procname       = "msg_max",
1182                 .data           = &msg_max,
1183                 .maxlen         = sizeof(int),
1184                 .mode           = 0644,
1185                 .proc_handler   = &proc_dointvec_minmax,
1186                 .extra1         = &msg_max_limit_min,
1187                 .extra2         = &msg_max_limit_max,
1188         },
1189         {
1190                 .ctl_name       = CTL_MSGSIZEMAX,
1191                 .procname       = "msgsize_max",
1192                 .data           = &msgsize_max,
1193                 .maxlen         = sizeof(int),
1194                 .mode           = 0644,
1195                 .proc_handler   = &proc_dointvec_minmax,
1196                 .extra1         = &msg_maxsize_limit_min,
1197                 .extra2         = &msg_maxsize_limit_max,
1198         },
1199         { .ctl_name = 0 }
1200 };
1201
1202 static ctl_table mq_sysctl_dir[] = {
1203         {
1204                 .ctl_name       = FS_MQUEUE,
1205                 .procname       = "mqueue",
1206                 .mode           = 0555,
1207                 .child          = mq_sysctls,
1208         },
1209         { .ctl_name = 0 }
1210 };
1211
1212 static ctl_table mq_sysctl_root[] = {
1213         {
1214                 .ctl_name       = CTL_FS,
1215                 .procname       = "fs",
1216                 .mode           = 0555,
1217                 .child          = mq_sysctl_dir,
1218         },
1219         { .ctl_name = 0 }
1220 };
1221
1222 static int __init init_mqueue_fs(void)
1223 {
1224         int error;
1225
1226         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1227                                 sizeof(struct mqueue_inode_info), 0,
1228                                 SLAB_HWCACHE_ALIGN, init_once, NULL);
1229         if (mqueue_inode_cachep == NULL)
1230                 return -ENOMEM;
1231
1232         /* ignore failues - they are not fatal */
1233         mq_sysctl_table = register_sysctl_table(mq_sysctl_root, 0);
1234
1235         error = register_filesystem(&mqueue_fs_type);
1236         if (error)
1237                 goto out_sysctl;
1238
1239         if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1240                 error = PTR_ERR(mqueue_mnt);
1241                 goto out_filesystem;
1242         }
1243
1244         /* internal initialization - not common for vfs */
1245         queues_count = 0;
1246         spin_lock_init(&mq_lock);
1247
1248         return 0;
1249
1250 out_filesystem:
1251         unregister_filesystem(&mqueue_fs_type);
1252 out_sysctl:
1253         if (mq_sysctl_table)
1254                 unregister_sysctl_table(mq_sysctl_table);
1255         if (kmem_cache_destroy(mqueue_inode_cachep)) {
1256                 printk(KERN_INFO
1257                         "mqueue_inode_cache: not all structures were freed\n");
1258         }
1259         return error;
1260 }
1261
1262 __initcall(init_mqueue_fs);