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