git.oblomov.eu Git - linux-2.6/blob - 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  * Audit:                   George Wilson           (ltcgcw@us.ibm.com)
  12  *
  13  * This file is released under the GPL.
  14  */
  15
  16 #include <linux/capability.h>
  17 #include <linux/init.h>
  18 #include <linux/pagemap.h>
  19 #include <linux/file.h>
  20 #include <linux/mount.h>
  21 #include <linux/namei.h>
  22 #include <linux/sysctl.h>
  23 #include <linux/poll.h>
  24 #include <linux/mqueue.h>
  25 #include <linux/msg.h>
  26 #include <linux/skbuff.h>
  27 #include <linux/netlink.h>
  28 #include <linux/syscalls.h>
  29 #include <linux/audit.h>
  30 #include <linux/signal.h>
  31 #include <linux/mutex.h>
  32
  33 #include <net/sock.h>
  34 #include "util.h"
  35
  36 #define MQUEUE_MAGIC    0x19800202
  37 #define DIRENT_SIZE     20
  38 #define FILENT_SIZE     80
  39
  40 #define SEND            0
  41 #define RECV            1
  42
  43 #define STATE_NONE      0
  44 #define STATE_PENDING   1
  45 #define STATE_READY     2
  46
  47 /* used by sysctl */
  48 #define FS_MQUEUE       1
  49 #define CTL_QUEUESMAX   2
  50 #define CTL_MSGMAX      3
  51 #define CTL_MSGSIZEMAX  4
  52
  53 /* default values */
  54 #define DFLT_QUEUESMAX  256     /* max number of message queues */
  55 #define DFLT_MSGMAX     10      /* max number of messages in each queue */
  56 #define HARD_MSGMAX     (131072/sizeof(void*))
  57 #define DFLT_MSGSIZEMAX 8192    /* max message size */
  58
  59
  60 struct ext_wait_queue {         /* queue of sleeping tasks */
  61         struct task_struct *task;
  62         struct list_head list;
  63         struct msg_msg *msg;    /* ptr of loaded message */
  64         int state;              /* one of STATE_* values */
  65 };
  66
  67 struct mqueue_inode_info {
  68         spinlock_t lock;
  69         struct inode vfs_inode;
  70         wait_queue_head_t wait_q;
  71
  72         struct msg_msg **messages;
  73         struct mq_attr attr;
  74
  75         struct sigevent notify;
  76         pid_t notify_owner;
  77         struct user_struct *user;       /* user who created, for accounting */
  78         struct sock *notify_sock;
  79         struct sk_buff *notify_cookie;
  80
  81         /* for tasks waiting for free space and messages, respectively */
  82         struct ext_wait_queue e_wait_q[2];
  83
  84         unsigned long qsize; /* size of queue in memory (sum of all msgs) */
  85 };
  86
  87 static struct inode_operations mqueue_dir_inode_operations;
  88 static struct file_operations mqueue_file_operations;
  89 static struct super_operations mqueue_super_ops;
  90 static void remove_notification(struct mqueue_inode_info *info);
  91
  92 static spinlock_t mq_lock;
  93 static kmem_cache_t *mqueue_inode_cachep;
  94 static struct vfsmount *mqueue_mnt;
  95
  96 static unsigned int queues_count;
  97 static unsigned int queues_max  = DFLT_QUEUESMAX;
  98 static unsigned int msg_max     = DFLT_MSGMAX;
  99 static unsigned int msgsize_max = DFLT_MSGSIZEMAX;
 100
 101 static struct ctl_table_header * mq_sysctl_table;
 102
 103 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
 104 {
 105         return container_of(inode, struct mqueue_inode_info, vfs_inode);
 106 }
 107
 108 static struct inode *mqueue_get_inode(struct super_block *sb, int mode,
 109                                                         struct mq_attr *attr)
 110 {
 111         struct inode *inode;
 112
 113         inode = new_inode(sb);
 114         if (inode) {
 115                 inode->i_mode = mode;
 116                 inode->i_uid = current->fsuid;
 117                 inode->i_gid = current->fsgid;
 118                 inode->i_blksize = PAGE_CACHE_SIZE;
 119                 inode->i_blocks = 0;
 120                 inode->i_mtime = inode->i_ctime = inode->i_atime =
 121                                 CURRENT_TIME;
 122
 123                 if (S_ISREG(mode)) {
 124                         struct mqueue_inode_info *info;
 125                         struct task_struct *p = current;
 126                         struct user_struct *u = p->user;
 127                         unsigned long mq_bytes, mq_msg_tblsz;
 128
 129                         inode->i_fop = &mqueue_file_operations;
 130                         inode->i_size = FILENT_SIZE;
 131                         /* mqueue specific info */
 132                         info = MQUEUE_I(inode);
 133                         spin_lock_init(&info->lock);
 134                         init_waitqueue_head(&info->wait_q);
 135                         INIT_LIST_HEAD(&info->e_wait_q[0].list);
 136                         INIT_LIST_HEAD(&info->e_wait_q[1].list);
 137                         info->messages = NULL;
 138                         info->notify_owner = 0;
 139                         info->qsize = 0;
 140                         info->user = NULL;      /* set when all is ok */
 141                         memset(&info->attr, 0, sizeof(info->attr));
 142                         info->attr.mq_maxmsg = DFLT_MSGMAX;
 143                         info->attr.mq_msgsize = DFLT_MSGSIZEMAX;
 144                         if (attr) {
 145                                 info->attr.mq_maxmsg = attr->mq_maxmsg;
 146                                 info->attr.mq_msgsize = attr->mq_msgsize;
 147                         }
 148                         mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
 149                         mq_bytes = (mq_msg_tblsz +
 150                                 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
 151
 152                         spin_lock(&mq_lock);
 153                         if (u->mq_bytes + mq_bytes < u->mq_bytes ||
 154                             u->mq_bytes + mq_bytes >
 155                             p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
 156                                 spin_unlock(&mq_lock);
 157                                 goto out_inode;
 158                         }
 159                         u->mq_bytes += mq_bytes;
 160                         spin_unlock(&mq_lock);
 161
 162                         info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
 163                         if (!info->messages) {
 164                                 spin_lock(&mq_lock);
 165                                 u->mq_bytes -= mq_bytes;
 166                                 spin_unlock(&mq_lock);
 167                                 goto out_inode;
 168                         }
 169                         /* all is ok */
 170                         info->user = get_uid(u);
 171                 } else if (S_ISDIR(mode)) {
 172                         inode->i_nlink++;
 173                         /* Some things misbehave if size == 0 on a directory */
 174                         inode->i_size = 2 * DIRENT_SIZE;
 175                         inode->i_op = &mqueue_dir_inode_operations;
 176                         inode->i_fop = &simple_dir_operations;
 177                 }
 178         }
 179         return inode;
 180 out_inode:
 181         make_bad_inode(inode);
 182         iput(inode);
 183         return NULL;
 184 }
 185
 186 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
 187 {
 188         struct inode *inode;
 189
 190         sb->s_blocksize = PAGE_CACHE_SIZE;
 191         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 192         sb->s_magic = MQUEUE_MAGIC;
 193         sb->s_op = &mqueue_super_ops;
 194
 195         inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
 196         if (!inode)
 197                 return -ENOMEM;
 198
 199         sb->s_root = d_alloc_root(inode);
 200         if (!sb->s_root) {
 201                 iput(inode);
 202                 return -ENOMEM;
 203         }
 204
 205         return 0;
 206 }
 207
 208 static int mqueue_get_sb(struct file_system_type *fs_type,
 209                          int flags, const char *dev_name,
 210                          void *data, struct vfsmount *mnt)
 211 {
 212         return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt);
 213 }
 214
 215 static void init_once(void *foo, kmem_cache_t * cachep, unsigned long flags)
 216 {
 217         struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
 218
 219         if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) ==
 220                 SLAB_CTOR_CONSTRUCTOR)
 221                 inode_init_once(&p->vfs_inode);
 222 }
 223
 224 static struct inode *mqueue_alloc_inode(struct super_block *sb)
 225 {
 226         struct mqueue_inode_info *ei;
 227
 228         ei = kmem_cache_alloc(mqueue_inode_cachep, SLAB_KERNEL);
 229         if (!ei)
 230                 return NULL;
 231         return &ei->vfs_inode;
 232 }
 233
 234 static void mqueue_destroy_inode(struct inode *inode)
 235 {
 236         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
 237 }
 238
 239 static void mqueue_delete_inode(struct inode *inode)
 240 {
 241         struct mqueue_inode_info *info;
 242         struct user_struct *user;
 243         unsigned long mq_bytes;
 244         int i;
 245
 246         if (S_ISDIR(inode->i_mode)) {
 247                 clear_inode(inode);
 248                 return;
 249         }
 250         info = MQUEUE_I(inode);
 251         spin_lock(&info->lock);
 252         for (i = 0; i < info->attr.mq_curmsgs; i++)
 253                 free_msg(info->messages[i]);
 254         kfree(info->messages);
 255         spin_unlock(&info->lock);
 256
 257         clear_inode(inode);
 258
 259         mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
 260                    (info->attr.mq_maxmsg * info->attr.mq_msgsize));
 261         user = info->user;
 262         if (user) {
 263                 spin_lock(&mq_lock);
 264                 user->mq_bytes -= mq_bytes;
 265                 queues_count--;
 266                 spin_unlock(&mq_lock);
 267                 free_uid(user);
 268         }
 269 }
 270
 271 static int mqueue_create(struct inode *dir, struct dentry *dentry,
 272                                 int mode, struct nameidata *nd)
 273 {
 274         struct inode *inode;
 275         struct mq_attr *attr = dentry->d_fsdata;
 276         int error;
 277
 278         spin_lock(&mq_lock);
 279         if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
 280                 error = -ENOSPC;
 281                 goto out_lock;
 282         }
 283         queues_count++;
 284         spin_unlock(&mq_lock);
 285
 286         inode = mqueue_get_inode(dir->i_sb, mode, attr);
 287         if (!inode) {
 288                 error = -ENOMEM;
 289                 spin_lock(&mq_lock);
 290                 queues_count--;
 291                 goto out_lock;
 292         }
 293
 294         dir->i_size += DIRENT_SIZE;
 295         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 296
 297         d_instantiate(dentry, inode);
 298         dget(dentry);
 299         return 0;
 300 out_lock:
 301         spin_unlock(&mq_lock);
 302         return error;
 303 }
 304
 305 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
 306 {
 307         struct inode *inode = dentry->d_inode;
 308
 309         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 310         dir->i_size -= DIRENT_SIZE;
 311         inode->i_nlink--;
 312         dput(dentry);
 313         return 0;
 314 }
 315
 316 /*
 317 *       This is routine for system read from queue file.
 318 *       To avoid mess with doing here some sort of mq_receive we allow
 319 *       to read only queue size & notification info (the only values
 320 *       that are interesting from user point of view and aren't accessible
 321 *       through std routines)
 322 */
 323 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
 324                                 size_t count, loff_t * off)
 325 {
 326         struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
 327         char buffer[FILENT_SIZE];
 328         size_t slen;
 329         loff_t o;
 330
 331         if (!count)
 332                 return 0;
 333
 334         spin_lock(&info->lock);
 335         snprintf(buffer, sizeof(buffer),
 336                         "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
 337                         info->qsize,
 338                         info->notify_owner ? info->notify.sigev_notify : 0,
 339                         (info->notify_owner &&
 340                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
 341                                 info->notify.sigev_signo : 0,
 342                         info->notify_owner);
 343         spin_unlock(&info->lock);
 344         buffer[sizeof(buffer)-1] = '\0';
 345         slen = strlen(buffer)+1;
 346
 347         o = *off;
 348         if (o > slen)
 349                 return 0;
 350
 351         if (o + count > slen)
 352                 count = slen - o;
 353
 354         if (copy_to_user(u_data, buffer + o, count))
 355                 return -EFAULT;
 356
 357         *off = o + count;
 358         filp->f_dentry->d_inode->i_atime = filp->f_dentry->d_inode->i_ctime = CURRENT_TIME;
 359         return count;
 360 }
 361
 362 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
 363 {
 364         struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
 365
 366         spin_lock(&info->lock);
 367         if (current->tgid == info->notify_owner)
 368                 remove_notification(info);
 369
 370         spin_unlock(&info->lock);
 371         return 0;
 372 }
 373
 374 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
 375 {
 376         struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
 377         int retval = 0;
 378
 379         poll_wait(filp, &info->wait_q, poll_tab);
 380
 381         spin_lock(&info->lock);
 382         if (info->attr.mq_curmsgs)
 383                 retval = POLLIN | POLLRDNORM;
 384
 385         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
 386                 retval |= POLLOUT | POLLWRNORM;
 387         spin_unlock(&info->lock);
 388
 389         return retval;
 390 }
 391
 392 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
 393 static void wq_add(struct mqueue_inode_info *info, int sr,
 394                         struct ext_wait_queue *ewp)
 395 {
 396         struct ext_wait_queue *walk;
 397
 398         ewp->task = current;
 399
 400         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
 401                 if (walk->task->static_prio <= current->static_prio) {
 402                         list_add_tail(&ewp->list, &walk->list);
 403                         return;
 404                 }
 405         }
 406         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
 407 }
 408
 409 /*
 410  * Puts current task to sleep. Caller must hold queue lock. After return
 411  * lock isn't held.
 412  * sr: SEND or RECV
 413  */
 414 static int wq_sleep(struct mqueue_inode_info *info, int sr,
 415                         long timeout, struct ext_wait_queue *ewp)
 416 {
 417         int retval;
 418         signed long time;
 419
 420         wq_add(info, sr, ewp);
 421
 422         for (;;) {
 423                 set_current_state(TASK_INTERRUPTIBLE);
 424
 425                 spin_unlock(&info->lock);
 426                 time = schedule_timeout(timeout);
 427
 428                 while (ewp->state == STATE_PENDING)
 429                         cpu_relax();
 430
 431                 if (ewp->state == STATE_READY) {
 432                         retval = 0;
 433                         goto out;
 434                 }
 435                 spin_lock(&info->lock);
 436                 if (ewp->state == STATE_READY) {
 437                         retval = 0;
 438                         goto out_unlock;
 439                 }
 440                 if (signal_pending(current)) {
 441                         retval = -ERESTARTSYS;
 442                         break;
 443                 }
 444                 if (time == 0) {
 445                         retval = -ETIMEDOUT;
 446                         break;
 447                 }
 448         }
 449         list_del(&ewp->list);
 450 out_unlock:
 451         spin_unlock(&info->lock);
 452 out:
 453         return retval;
 454 }
 455
 456 /*
 457  * Returns waiting task that should be serviced first or NULL if none exists
 458  */
 459 static struct ext_wait_queue *wq_get_first_waiter(
 460                 struct mqueue_inode_info *info, int sr)
 461 {
 462         struct list_head *ptr;
 463
 464         ptr = info->e_wait_q[sr].list.prev;
 465         if (ptr == &info->e_wait_q[sr].list)
 466                 return NULL;
 467         return list_entry(ptr, struct ext_wait_queue, list);
 468 }
 469
 470 /* Auxiliary functions to manipulate messages' list */
 471 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
 472 {
 473         int k;
 474
 475         k = info->attr.mq_curmsgs - 1;
 476         while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
 477                 info->messages[k + 1] = info->messages[k];
 478                 k--;
 479         }
 480         info->attr.mq_curmsgs++;
 481         info->qsize += ptr->m_ts;
 482         info->messages[k + 1] = ptr;
 483 }
 484
 485 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
 486 {
 487         info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
 488         return info->messages[info->attr.mq_curmsgs];
 489 }
 490
 491 static inline void set_cookie(struct sk_buff *skb, char code)
 492 {
 493         ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
 494 }
 495
 496 /*
 497  * The next function is only to split too long sys_mq_timedsend
 498  */
 499 static void __do_notify(struct mqueue_inode_info *info)
 500 {
 501         /* notification
 502          * invoked when there is registered process and there isn't process
 503          * waiting synchronously for message AND state of queue changed from
 504          * empty to not empty. Here we are sure that no one is waiting
 505          * synchronously. */
 506         if (info->notify_owner &&
 507             info->attr.mq_curmsgs == 1) {
 508                 struct siginfo sig_i;
 509                 switch (info->notify.sigev_notify) {
 510                 case SIGEV_NONE:
 511                         break;
 512                 case SIGEV_SIGNAL:
 513                         /* sends signal */
 514
 515                         sig_i.si_signo = info->notify.sigev_signo;
 516                         sig_i.si_errno = 0;
 517                         sig_i.si_code = SI_MESGQ;
 518                         sig_i.si_value = info->notify.sigev_value;
 519                         sig_i.si_pid = current->tgid;
 520                         sig_i.si_uid = current->uid;
 521
 522                         kill_proc_info(info->notify.sigev_signo,
 523                                        &sig_i, info->notify_owner);
 524                         break;
 525                 case SIGEV_THREAD:
 526                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
 527                         netlink_sendskb(info->notify_sock,
 528                                         info->notify_cookie, 0);
 529                         break;
 530                 }
 531                 /* after notification unregisters process */
 532                 info->notify_owner = 0;
 533         }
 534         wake_up(&info->wait_q);
 535 }
 536
 537 static long prepare_timeout(const struct timespec __user *u_arg)
 538 {
 539         struct timespec ts, nowts;
 540         long timeout;
 541
 542         if (u_arg) {
 543                 if (unlikely(copy_from_user(&ts, u_arg,
 544                                         sizeof(struct timespec))))
 545                         return -EFAULT;
 546
 547                 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0
 548                         || ts.tv_nsec >= NSEC_PER_SEC))
 549                         return -EINVAL;
 550                 nowts = CURRENT_TIME;
 551                 /* first subtract as jiffies can't be too big */
 552                 ts.tv_sec -= nowts.tv_sec;
 553                 if (ts.tv_nsec < nowts.tv_nsec) {
 554                         ts.tv_nsec += NSEC_PER_SEC;
 555                         ts.tv_sec--;
 556                 }
 557                 ts.tv_nsec -= nowts.tv_nsec;
 558                 if (ts.tv_sec < 0)
 559                         return 0;
 560
 561                 timeout = timespec_to_jiffies(&ts) + 1;
 562         } else
 563                 return MAX_SCHEDULE_TIMEOUT;
 564
 565         return timeout;
 566 }
 567
 568 static void remove_notification(struct mqueue_inode_info *info)
 569 {
 570         if (info->notify_owner != 0 &&
 571             info->notify.sigev_notify == SIGEV_THREAD) {
 572                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
 573                 netlink_sendskb(info->notify_sock, info->notify_cookie, 0);
 574         }
 575         info->notify_owner = 0;
 576 }
 577
 578 static int mq_attr_ok(struct mq_attr *attr)
 579 {
 580         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
 581                 return 0;
 582         if (capable(CAP_SYS_RESOURCE)) {
 583                 if (attr->mq_maxmsg > HARD_MSGMAX)
 584                         return 0;
 585         } else {
 586                 if (attr->mq_maxmsg > msg_max ||
 587                                 attr->mq_msgsize > msgsize_max)
 588                         return 0;
 589         }
 590         /* check for overflow */
 591         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
 592                 return 0;
 593         if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
 594             (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
 595             (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
 596                 return 0;
 597         return 1;
 598 }
 599
 600 /*
 601  * Invoked when creating a new queue via sys_mq_open
 602  */
 603 static struct file *do_create(struct dentry *dir, struct dentry *dentry,
 604                         int oflag, mode_t mode, struct mq_attr __user *u_attr)
 605 {
 606         struct mq_attr attr;
 607         int ret;
 608
 609         if (u_attr) {
 610                 ret = -EFAULT;
 611                 if (copy_from_user(&attr, u_attr, sizeof(attr)))
 612                         goto out;
 613                 ret = -EINVAL;
 614                 if (!mq_attr_ok(&attr))
 615                         goto out;
 616                 /* store for use during create */
 617                 dentry->d_fsdata = &attr;
 618         }
 619
 620         mode &= ~current->fs->umask;
 621         ret = vfs_create(dir->d_inode, dentry, mode, NULL);
 622         dentry->d_fsdata = NULL;
 623         if (ret)
 624                 goto out;
 625
 626         return dentry_open(dentry, mqueue_mnt, oflag);
 627
 628 out:
 629         dput(dentry);
 630         mntput(mqueue_mnt);
 631         return ERR_PTR(ret);
 632 }
 633
 634 /* Opens existing queue */
 635 static struct file *do_open(struct dentry *dentry, int oflag)
 636 {
 637 static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
 638                                         MAY_READ | MAY_WRITE };
 639
 640         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
 641                 dput(dentry);
 642                 mntput(mqueue_mnt);
 643                 return ERR_PTR(-EINVAL);
 644         }
 645
 646         if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) {
 647                 dput(dentry);
 648                 mntput(mqueue_mnt);
 649                 return ERR_PTR(-EACCES);
 650         }
 651
 652         return dentry_open(dentry, mqueue_mnt, oflag);
 653 }
 654
 655 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
 656                                 struct mq_attr __user *u_attr)
 657 {
 658         struct dentry *dentry;
 659         struct file *filp;
 660         char *name;
 661         int fd, error;
 662
 663         error = audit_mq_open(oflag, mode, u_attr);
 664         if (error != 0)
 665                 return error;
 666
 667         if (IS_ERR(name = getname(u_name)))
 668                 return PTR_ERR(name);
 669
 670         fd = get_unused_fd();
 671         if (fd < 0)
 672                 goto out_putname;
 673
 674         mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
 675         dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
 676         if (IS_ERR(dentry)) {
 677                 error = PTR_ERR(dentry);
 678                 goto out_err;
 679         }
 680         mntget(mqueue_mnt);
 681
 682         if (oflag & O_CREAT) {
 683                 if (dentry->d_inode) {  /* entry already exists */
 684                         error = -EEXIST;
 685                         if (oflag & O_EXCL)
 686                                 goto out;
 687                         filp = do_open(dentry, oflag);
 688                 } else {
 689                         filp = do_create(mqueue_mnt->mnt_root, dentry,
 690                                                 oflag, mode, u_attr);
 691                 }
 692         } else {
 693                 error = -ENOENT;
 694                 if (!dentry->d_inode)
 695                         goto out;
 696                 filp = do_open(dentry, oflag);
 697         }
 698
 699         if (IS_ERR(filp)) {
 700                 error = PTR_ERR(filp);
 701                 goto out_putfd;
 702         }
 703
 704         set_close_on_exec(fd, 1);
 705         fd_install(fd, filp);
 706         goto out_upsem;
 707
 708 out:
 709         dput(dentry);
 710         mntput(mqueue_mnt);
 711 out_putfd:
 712         put_unused_fd(fd);
 713 out_err:
 714         fd = error;
 715 out_upsem:
 716         mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
 717 out_putname:
 718         putname(name);
 719         return fd;
 720 }
 721
 722 asmlinkage long sys_mq_unlink(const char __user *u_name)
 723 {
 724         int err;
 725         char *name;
 726         struct dentry *dentry;
 727         struct inode *inode = NULL;
 728
 729         name = getname(u_name);
 730         if (IS_ERR(name))
 731                 return PTR_ERR(name);
 732
 733         mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
 734         dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
 735         if (IS_ERR(dentry)) {
 736                 err = PTR_ERR(dentry);
 737                 goto out_unlock;
 738         }
 739
 740         if (!dentry->d_inode) {
 741                 err = -ENOENT;
 742                 goto out_err;
 743         }
 744
 745         inode = dentry->d_inode;
 746         if (inode)
 747                 atomic_inc(&inode->i_count);
 748
 749         err = vfs_unlink(dentry->d_parent->d_inode, dentry);
 750 out_err:
 751         dput(dentry);
 752
 753 out_unlock:
 754         mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
 755         putname(name);
 756         if (inode)
 757                 iput(inode);
 758
 759         return err;
 760 }
 761
 762 /* Pipelined send and receive functions.
 763  *
 764  * If a receiver finds no waiting message, then it registers itself in the
 765  * list of waiting receivers. A sender checks that list before adding the new
 766  * message into the message array. If there is a waiting receiver, then it
 767  * bypasses the message array and directly hands the message over to the
 768  * receiver.
 769  * The receiver accepts the message and returns without grabbing the queue
 770  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
 771  * are necessary. The same algorithm is used for sysv semaphores, see
 772  * ipc/sem.c for more details.
 773  *
 774  * The same algorithm is used for senders.
 775  */
 776
 777 /* pipelined_send() - send a message directly to the task waiting in
 778  * sys_mq_timedreceive() (without inserting message into a queue).
 779  */
 780 static inline void pipelined_send(struct mqueue_inode_info *info,
 781                                   struct msg_msg *message,
 782                                   struct ext_wait_queue *receiver)
 783 {
 784         receiver->msg = message;
 785         list_del(&receiver->list);
 786         receiver->state = STATE_PENDING;
 787         wake_up_process(receiver->task);
 788         smp_wmb();
 789         receiver->state = STATE_READY;
 790 }
 791
 792 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
 793  * gets its message and put to the queue (we have one free place for sure). */
 794 static inline void pipelined_receive(struct mqueue_inode_info *info)
 795 {
 796         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
 797
 798         if (!sender) {
 799                 /* for poll */
 800                 wake_up_interruptible(&info->wait_q);
 801                 return;
 802         }
 803         msg_insert(sender->msg, info);
 804         list_del(&sender->list);
 805         sender->state = STATE_PENDING;
 806         wake_up_process(sender->task);
 807         smp_wmb();
 808         sender->state = STATE_READY;
 809 }
 810
 811 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
 812         size_t msg_len, unsigned int msg_prio,
 813         const struct timespec __user *u_abs_timeout)
 814 {
 815         struct file *filp;
 816         struct inode *inode;
 817         struct ext_wait_queue wait;
 818         struct ext_wait_queue *receiver;
 819         struct msg_msg *msg_ptr;
 820         struct mqueue_inode_info *info;
 821         long timeout;
 822         int ret;
 823
 824         ret = audit_mq_timedsend(mqdes, msg_len, msg_prio, u_abs_timeout);
 825         if (ret != 0)
 826                 return ret;
 827
 828         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
 829                 return -EINVAL;
 830
 831         timeout = prepare_timeout(u_abs_timeout);
 832
 833         ret = -EBADF;
 834         filp = fget(mqdes);
 835         if (unlikely(!filp))
 836                 goto out;
 837
 838         inode = filp->f_dentry->d_inode;
 839         if (unlikely(filp->f_op != &mqueue_file_operations))
 840                 goto out_fput;
 841         info = MQUEUE_I(inode);
 842
 843         if (unlikely(!(filp->f_mode & FMODE_WRITE)))
 844                 goto out_fput;
 845
 846         if (unlikely(msg_len > info->attr.mq_msgsize)) {
 847                 ret = -EMSGSIZE;
 848                 goto out_fput;
 849         }
 850
 851         /* First try to allocate memory, before doing anything with
 852          * existing queues. */
 853         msg_ptr = load_msg(u_msg_ptr, msg_len);
 854         if (IS_ERR(msg_ptr)) {
 855                 ret = PTR_ERR(msg_ptr);
 856                 goto out_fput;
 857         }
 858         msg_ptr->m_ts = msg_len;
 859         msg_ptr->m_type = msg_prio;
 860
 861         spin_lock(&info->lock);
 862
 863         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
 864                 if (filp->f_flags & O_NONBLOCK) {
 865                         spin_unlock(&info->lock);
 866                         ret = -EAGAIN;
 867                 } else if (unlikely(timeout < 0)) {
 868                         spin_unlock(&info->lock);
 869                         ret = timeout;
 870                 } else {
 871                         wait.task = current;
 872                         wait.msg = (void *) msg_ptr;
 873                         wait.state = STATE_NONE;
 874                         ret = wq_sleep(info, SEND, timeout, &wait);
 875                 }
 876                 if (ret < 0)
 877                         free_msg(msg_ptr);
 878         } else {
 879                 receiver = wq_get_first_waiter(info, RECV);
 880                 if (receiver) {
 881                         pipelined_send(info, msg_ptr, receiver);
 882                 } else {
 883                         /* adds message to the queue */
 884                         msg_insert(msg_ptr, info);
 885                         __do_notify(info);
 886                 }
 887                 inode->i_atime = inode->i_mtime = inode->i_ctime =
 888                                 CURRENT_TIME;
 889                 spin_unlock(&info->lock);
 890                 ret = 0;
 891         }
 892 out_fput:
 893         fput(filp);
 894 out:
 895         return ret;
 896 }
 897
 898 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
 899         size_t msg_len, unsigned int __user *u_msg_prio,
 900         const struct timespec __user *u_abs_timeout)
 901 {
 902         long timeout;
 903         ssize_t ret;
 904         struct msg_msg *msg_ptr;
 905         struct file *filp;
 906         struct inode *inode;
 907         struct mqueue_inode_info *info;
 908         struct ext_wait_queue wait;
 909
 910         ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout);
 911         if (ret != 0)
 912                 return ret;
 913
 914         timeout = prepare_timeout(u_abs_timeout);
 915
 916         ret = -EBADF;
 917         filp = fget(mqdes);
 918         if (unlikely(!filp))
 919                 goto out;
 920
 921         inode = filp->f_dentry->d_inode;
 922         if (unlikely(filp->f_op != &mqueue_file_operations))
 923                 goto out_fput;
 924         info = MQUEUE_I(inode);
 925
 926         if (unlikely(!(filp->f_mode & FMODE_READ)))
 927                 goto out_fput;
 928
 929         /* checks if buffer is big enough */
 930         if (unlikely(msg_len < info->attr.mq_msgsize)) {
 931                 ret = -EMSGSIZE;
 932                 goto out_fput;
 933         }
 934
 935         spin_lock(&info->lock);
 936         if (info->attr.mq_curmsgs == 0) {
 937                 if (filp->f_flags & O_NONBLOCK) {
 938                         spin_unlock(&info->lock);
 939                         ret = -EAGAIN;
 940                         msg_ptr = NULL;
 941                 } else if (unlikely(timeout < 0)) {
 942                         spin_unlock(&info->lock);
 943                         ret = timeout;
 944                         msg_ptr = NULL;
 945                 } else {
 946                         wait.task = current;
 947                         wait.state = STATE_NONE;
 948                         ret = wq_sleep(info, RECV, timeout, &wait);
 949                         msg_ptr = wait.msg;
 950                 }
 951         } else {
 952                 msg_ptr = msg_get(info);
 953
 954                 inode->i_atime = inode->i_mtime = inode->i_ctime =
 955                                 CURRENT_TIME;
 956
 957                 /* There is now free space in queue. */
 958                 pipelined_receive(info);
 959                 spin_unlock(&info->lock);
 960                 ret = 0;
 961         }
 962         if (ret == 0) {
 963                 ret = msg_ptr->m_ts;
 964
 965                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
 966                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
 967                         ret = -EFAULT;
 968                 }
 969                 free_msg(msg_ptr);
 970         }
 971 out_fput:
 972         fput(filp);
 973 out:
 974         return ret;
 975 }
 976
 977 /*
 978  * Notes: the case when user wants us to deregister (with NULL as pointer)
 979  * and he isn't currently owner of notification, will be silently discarded.
 980  * It isn't explicitly defined in the POSIX.
 981  */
 982 asmlinkage long sys_mq_notify(mqd_t mqdes,
 983                                 const struct sigevent __user *u_notification)
 984 {
 985         int ret;
 986         struct file *filp;
 987         struct sock *sock;
 988         struct inode *inode;
 989         struct sigevent notification;
 990         struct mqueue_inode_info *info;
 991         struct sk_buff *nc;
 992
 993         ret = audit_mq_notify(mqdes, u_notification);
 994         if (ret != 0)
 995                 return ret;
 996
 997         nc = NULL;
 998         sock = NULL;
 999         if (u_notification != NULL) {
1000                 if (copy_from_user(&notification, u_notification,
1001                                         sizeof(struct sigevent)))
1002                         return -EFAULT;
1003
1004                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1005                              notification.sigev_notify != SIGEV_SIGNAL &&
1006                              notification.sigev_notify != SIGEV_THREAD))
1007                         return -EINVAL;
1008                 if (notification.sigev_notify == SIGEV_SIGNAL &&
1009                         !valid_signal(notification.sigev_signo)) {
1010                         return -EINVAL;
1011                 }
1012                 if (notification.sigev_notify == SIGEV_THREAD) {
1013                         /* create the notify skb */
1014                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1015                         ret = -ENOMEM;
1016                         if (!nc)
1017                                 goto out;
1018                         ret = -EFAULT;
1019                         if (copy_from_user(nc->data,
1020                                         notification.sigev_value.sival_ptr,
1021                                         NOTIFY_COOKIE_LEN)) {
1022                                 goto out;
1023                         }
1024
1025                         /* TODO: add a header? */
1026                         skb_put(nc, NOTIFY_COOKIE_LEN);
1027                         /* and attach it to the socket */
1028 retry:
1029                         filp = fget(notification.sigev_signo);
1030                         ret = -EBADF;
1031                         if (!filp)
1032                                 goto out;
1033                         sock = netlink_getsockbyfilp(filp);
1034                         fput(filp);
1035                         if (IS_ERR(sock)) {
1036                                 ret = PTR_ERR(sock);
1037                                 sock = NULL;
1038                                 goto out;
1039                         }
1040
1041                         ret = netlink_attachskb(sock, nc, 0,
1042                                         MAX_SCHEDULE_TIMEOUT, NULL);
1043                         if (ret == 1)
1044                                 goto retry;
1045                         if (ret) {
1046                                 sock = NULL;
1047                                 nc = NULL;
1048                                 goto out;
1049                         }
1050                 }
1051         }
1052
1053         ret = -EBADF;
1054         filp = fget(mqdes);
1055         if (!filp)
1056                 goto out;
1057
1058         inode = filp->f_dentry->d_inode;
1059         if (unlikely(filp->f_op != &mqueue_file_operations))
1060                 goto out_fput;
1061         info = MQUEUE_I(inode);
1062
1063         ret = 0;
1064         spin_lock(&info->lock);
1065         if (u_notification == NULL) {
1066                 if (info->notify_owner == current->tgid) {
1067                         remove_notification(info);
1068                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1069                 }
1070         } else if (info->notify_owner != 0) {
1071                 ret = -EBUSY;
1072         } else {
1073                 switch (notification.sigev_notify) {
1074                 case SIGEV_NONE:
1075                         info->notify.sigev_notify = SIGEV_NONE;
1076                         break;
1077                 case SIGEV_THREAD:
1078                         info->notify_sock = sock;
1079                         info->notify_cookie = nc;
1080                         sock = NULL;
1081                         nc = NULL;
1082                         info->notify.sigev_notify = SIGEV_THREAD;
1083                         break;
1084                 case SIGEV_SIGNAL:
1085                         info->notify.sigev_signo = notification.sigev_signo;
1086                         info->notify.sigev_value = notification.sigev_value;
1087                         info->notify.sigev_notify = SIGEV_SIGNAL;
1088                         break;
1089                 }
1090                 info->notify_owner = current->tgid;
1091                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1092         }
1093         spin_unlock(&info->lock);
1094 out_fput:
1095         fput(filp);
1096 out:
1097         if (sock) {
1098                 netlink_detachskb(sock, nc);
1099         } else if (nc) {
1100                 dev_kfree_skb(nc);
1101         }
1102         return ret;
1103 }
1104
1105 asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1106                         const struct mq_attr __user *u_mqstat,
1107                         struct mq_attr __user *u_omqstat)
1108 {
1109         int ret;
1110         struct mq_attr mqstat, omqstat;
1111         struct file *filp;
1112         struct inode *inode;
1113         struct mqueue_inode_info *info;
1114
1115         if (u_mqstat != NULL) {
1116                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1117                         return -EFAULT;
1118                 if (mqstat.mq_flags & (~O_NONBLOCK))
1119                         return -EINVAL;
1120         }
1121
1122         ret = -EBADF;
1123         filp = fget(mqdes);
1124         if (!filp)
1125                 goto out;
1126
1127         inode = filp->f_dentry->d_inode;
1128         if (unlikely(filp->f_op != &mqueue_file_operations))
1129                 goto out_fput;
1130         info = MQUEUE_I(inode);
1131
1132         spin_lock(&info->lock);
1133
1134         omqstat = info->attr;
1135         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1136         if (u_mqstat) {
1137                 ret = audit_mq_getsetattr(mqdes, &mqstat);
1138                 if (ret != 0)
1139                         goto out;
1140                 if (mqstat.mq_flags & O_NONBLOCK)
1141                         filp->f_flags |= O_NONBLOCK;
1142                 else
1143                         filp->f_flags &= ~O_NONBLOCK;
1144
1145                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1146         }
1147
1148         spin_unlock(&info->lock);
1149
1150         ret = 0;
1151         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1152                                                 sizeof(struct mq_attr)))
1153                 ret = -EFAULT;
1154
1155 out_fput:
1156         fput(filp);
1157 out:
1158         return ret;
1159 }
1160
1161 static struct inode_operations mqueue_dir_inode_operations = {
1162         .lookup = simple_lookup,
1163         .create = mqueue_create,
1164         .unlink = mqueue_unlink,
1165 };
1166
1167 static struct file_operations mqueue_file_operations = {
1168         .flush = mqueue_flush_file,
1169         .poll = mqueue_poll_file,
1170         .read = mqueue_read_file,
1171 };
1172
1173 static struct super_operations mqueue_super_ops = {
1174         .alloc_inode = mqueue_alloc_inode,
1175         .destroy_inode = mqueue_destroy_inode,
1176         .statfs = simple_statfs,
1177         .delete_inode = mqueue_delete_inode,
1178         .drop_inode = generic_delete_inode,
1179 };
1180
1181 static struct file_system_type mqueue_fs_type = {
1182         .name = "mqueue",
1183         .get_sb = mqueue_get_sb,
1184         .kill_sb = kill_litter_super,
1185 };
1186
1187 static int msg_max_limit_min = DFLT_MSGMAX;
1188 static int msg_max_limit_max = HARD_MSGMAX;
1189
1190 static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX;
1191 static int msg_maxsize_limit_max = INT_MAX;
1192
1193 static ctl_table mq_sysctls[] = {
1194         {
1195                 .ctl_name       = CTL_QUEUESMAX,
1196                 .procname       = "queues_max",
1197                 .data           = &queues_max,
1198                 .maxlen         = sizeof(int),
1199                 .mode           = 0644,
1200                 .proc_handler   = &proc_dointvec,
1201         },
1202         {
1203                 .ctl_name       = CTL_MSGMAX,
1204                 .procname       = "msg_max",
1205                 .data           = &msg_max,
1206                 .maxlen         = sizeof(int),
1207                 .mode           = 0644,
1208                 .proc_handler   = &proc_dointvec_minmax,
1209                 .extra1         = &msg_max_limit_min,
1210                 .extra2         = &msg_max_limit_max,
1211         },
1212         {
1213                 .ctl_name       = CTL_MSGSIZEMAX,
1214                 .procname       = "msgsize_max",
1215                 .data           = &msgsize_max,
1216                 .maxlen         = sizeof(int),
1217                 .mode           = 0644,
1218                 .proc_handler   = &proc_dointvec_minmax,
1219                 .extra1         = &msg_maxsize_limit_min,
1220                 .extra2         = &msg_maxsize_limit_max,
1221         },
1222         { .ctl_name = 0 }
1223 };
1224
1225 static ctl_table mq_sysctl_dir[] = {
1226         {
1227                 .ctl_name       = FS_MQUEUE,
1228                 .procname       = "mqueue",
1229                 .mode           = 0555,
1230                 .child          = mq_sysctls,
1231         },
1232         { .ctl_name = 0 }
1233 };
1234
1235 static ctl_table mq_sysctl_root[] = {
1236         {
1237                 .ctl_name       = CTL_FS,
1238                 .procname       = "fs",
1239                 .mode           = 0555,
1240                 .child          = mq_sysctl_dir,
1241         },
1242         { .ctl_name = 0 }
1243 };
1244
1245 static int __init init_mqueue_fs(void)
1246 {
1247         int error;
1248
1249         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1250                                 sizeof(struct mqueue_inode_info), 0,
1251                                 SLAB_HWCACHE_ALIGN, init_once, NULL);
1252         if (mqueue_inode_cachep == NULL)
1253                 return -ENOMEM;
1254
1255         /* ignore failues - they are not fatal */
1256         mq_sysctl_table = register_sysctl_table(mq_sysctl_root, 0);
1257
1258         error = register_filesystem(&mqueue_fs_type);
1259         if (error)
1260                 goto out_sysctl;
1261
1262         if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1263                 error = PTR_ERR(mqueue_mnt);
1264                 goto out_filesystem;
1265         }
1266
1267         /* internal initialization - not common for vfs */
1268         queues_count = 0;
1269         spin_lock_init(&mq_lock);
1270
1271         return 0;
1272
1273 out_filesystem:
1274         unregister_filesystem(&mqueue_fs_type);
1275 out_sysctl:
1276         if (mq_sysctl_table)
1277                 unregister_sysctl_table(mq_sysctl_table);
1278         if (kmem_cache_destroy(mqueue_inode_cachep)) {
1279                 printk(KERN_INFO
1280                         "mqueue_inode_cache: not all structures were freed\n");
1281         }
1282         return error;
1283 }
1284
1285 __initcall(init_mqueue_fs);