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
  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         struct pid* 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 const struct inode_operations mqueue_dir_inode_operations;
  88 static const 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 struct kmem_cache *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_blocks = 0;
 119                 inode->i_mtime = inode->i_ctime = inode->i_atime =
 120                                 CURRENT_TIME;
 121
 122                 if (S_ISREG(mode)) {
 123                         struct mqueue_inode_info *info;
 124                         struct task_struct *p = current;
 125                         struct user_struct *u = p->user;
 126                         unsigned long mq_bytes, mq_msg_tblsz;
 127
 128                         inode->i_fop = &mqueue_file_operations;
 129                         inode->i_size = FILENT_SIZE;
 130                         /* mqueue specific info */
 131                         info = MQUEUE_I(inode);
 132                         spin_lock_init(&info->lock);
 133                         init_waitqueue_head(&info->wait_q);
 134                         INIT_LIST_HEAD(&info->e_wait_q[0].list);
 135                         INIT_LIST_HEAD(&info->e_wait_q[1].list);
 136                         info->messages = NULL;
 137                         info->notify_owner = NULL;
 138                         info->qsize = 0;
 139                         info->user = NULL;      /* set when all is ok */
 140                         memset(&info->attr, 0, sizeof(info->attr));
 141                         info->attr.mq_maxmsg = DFLT_MSGMAX;
 142                         info->attr.mq_msgsize = DFLT_MSGSIZEMAX;
 143                         if (attr) {
 144                                 info->attr.mq_maxmsg = attr->mq_maxmsg;
 145                                 info->attr.mq_msgsize = attr->mq_msgsize;
 146                         }
 147                         mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
 148                         mq_bytes = (mq_msg_tblsz +
 149                                 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
 150
 151                         spin_lock(&mq_lock);
 152                         if (u->mq_bytes + mq_bytes < u->mq_bytes ||
 153                             u->mq_bytes + mq_bytes >
 154                             p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
 155                                 spin_unlock(&mq_lock);
 156                                 goto out_inode;
 157                         }
 158                         u->mq_bytes += mq_bytes;
 159                         spin_unlock(&mq_lock);
 160
 161                         info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
 162                         if (!info->messages) {
 163                                 spin_lock(&mq_lock);
 164                                 u->mq_bytes -= mq_bytes;
 165                                 spin_unlock(&mq_lock);
 166                                 goto out_inode;
 167                         }
 168                         /* all is ok */
 169                         info->user = get_uid(u);
 170                 } else if (S_ISDIR(mode)) {
 171                         inc_nlink(inode);
 172                         /* Some things misbehave if size == 0 on a directory */
 173                         inode->i_size = 2 * DIRENT_SIZE;
 174                         inode->i_op = &mqueue_dir_inode_operations;
 175                         inode->i_fop = &simple_dir_operations;
 176                 }
 177         }
 178         return inode;
 179 out_inode:
 180         make_bad_inode(inode);
 181         iput(inode);
 182         return NULL;
 183 }
 184
 185 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
 186 {
 187         struct inode *inode;
 188
 189         sb->s_blocksize = PAGE_CACHE_SIZE;
 190         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 191         sb->s_magic = MQUEUE_MAGIC;
 192         sb->s_op = &mqueue_super_ops;
 193
 194         inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
 195         if (!inode)
 196                 return -ENOMEM;
 197
 198         sb->s_root = d_alloc_root(inode);
 199         if (!sb->s_root) {
 200                 iput(inode);
 201                 return -ENOMEM;
 202         }
 203
 204         return 0;
 205 }
 206
 207 static int mqueue_get_sb(struct file_system_type *fs_type,
 208                          int flags, const char *dev_name,
 209                          void *data, struct vfsmount *mnt)
 210 {
 211         return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt);
 212 }
 213
 214 static void init_once(void *foo, struct kmem_cache * cachep, unsigned long flags)
 215 {
 216         struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
 217
 218         inode_init_once(&p->vfs_inode);
 219 }
 220
 221 static struct inode *mqueue_alloc_inode(struct super_block *sb)
 222 {
 223         struct mqueue_inode_info *ei;
 224
 225         ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
 226         if (!ei)
 227                 return NULL;
 228         return &ei->vfs_inode;
 229 }
 230
 231 static void mqueue_destroy_inode(struct inode *inode)
 232 {
 233         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
 234 }
 235
 236 static void mqueue_delete_inode(struct inode *inode)
 237 {
 238         struct mqueue_inode_info *info;
 239         struct user_struct *user;
 240         unsigned long mq_bytes;
 241         int i;
 242
 243         if (S_ISDIR(inode->i_mode)) {
 244                 clear_inode(inode);
 245                 return;
 246         }
 247         info = MQUEUE_I(inode);
 248         spin_lock(&info->lock);
 249         for (i = 0; i < info->attr.mq_curmsgs; i++)
 250                 free_msg(info->messages[i]);
 251         kfree(info->messages);
 252         spin_unlock(&info->lock);
 253
 254         clear_inode(inode);
 255
 256         mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
 257                    (info->attr.mq_maxmsg * info->attr.mq_msgsize));
 258         user = info->user;
 259         if (user) {
 260                 spin_lock(&mq_lock);
 261                 user->mq_bytes -= mq_bytes;
 262                 queues_count--;
 263                 spin_unlock(&mq_lock);
 264                 free_uid(user);
 265         }
 266 }
 267
 268 static int mqueue_create(struct inode *dir, struct dentry *dentry,
 269                                 int mode, struct nameidata *nd)
 270 {
 271         struct inode *inode;
 272         struct mq_attr *attr = dentry->d_fsdata;
 273         int error;
 274
 275         spin_lock(&mq_lock);
 276         if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
 277                 error = -ENOSPC;
 278                 goto out_lock;
 279         }
 280         queues_count++;
 281         spin_unlock(&mq_lock);
 282
 283         inode = mqueue_get_inode(dir->i_sb, mode, attr);
 284         if (!inode) {
 285                 error = -ENOMEM;
 286                 spin_lock(&mq_lock);
 287                 queues_count--;
 288                 goto out_lock;
 289         }
 290
 291         dir->i_size += DIRENT_SIZE;
 292         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 293
 294         d_instantiate(dentry, inode);
 295         dget(dentry);
 296         return 0;
 297 out_lock:
 298         spin_unlock(&mq_lock);
 299         return error;
 300 }
 301
 302 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
 303 {
 304         struct inode *inode = dentry->d_inode;
 305
 306         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 307         dir->i_size -= DIRENT_SIZE;
 308         drop_nlink(inode);
 309         dput(dentry);
 310         return 0;
 311 }
 312
 313 /*
 314 *       This is routine for system read from queue file.
 315 *       To avoid mess with doing here some sort of mq_receive we allow
 316 *       to read only queue size & notification info (the only values
 317 *       that are interesting from user point of view and aren't accessible
 318 *       through std routines)
 319 */
 320 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
 321                                 size_t count, loff_t * off)
 322 {
 323         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 324         char buffer[FILENT_SIZE];
 325         size_t slen;
 326         loff_t o;
 327
 328         if (!count)
 329                 return 0;
 330
 331         spin_lock(&info->lock);
 332         snprintf(buffer, sizeof(buffer),
 333                         "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
 334                         info->qsize,
 335                         info->notify_owner ? info->notify.sigev_notify : 0,
 336                         (info->notify_owner &&
 337                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
 338                                 info->notify.sigev_signo : 0,
 339                         pid_nr(info->notify_owner));
 340         spin_unlock(&info->lock);
 341         buffer[sizeof(buffer)-1] = '\0';
 342         slen = strlen(buffer)+1;
 343
 344         o = *off;
 345         if (o > slen)
 346                 return 0;
 347
 348         if (o + count > slen)
 349                 count = slen - o;
 350
 351         if (copy_to_user(u_data, buffer + o, count))
 352                 return -EFAULT;
 353
 354         *off = o + count;
 355         filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
 356         return count;
 357 }
 358
 359 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
 360 {
 361         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 362
 363         spin_lock(&info->lock);
 364         if (task_tgid(current) == info->notify_owner)
 365                 remove_notification(info);
 366
 367         spin_unlock(&info->lock);
 368         return 0;
 369 }
 370
 371 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
 372 {
 373         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 374         int retval = 0;
 375
 376         poll_wait(filp, &info->wait_q, poll_tab);
 377
 378         spin_lock(&info->lock);
 379         if (info->attr.mq_curmsgs)
 380                 retval = POLLIN | POLLRDNORM;
 381
 382         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
 383                 retval |= POLLOUT | POLLWRNORM;
 384         spin_unlock(&info->lock);
 385
 386         return retval;
 387 }
 388
 389 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
 390 static void wq_add(struct mqueue_inode_info *info, int sr,
 391                         struct ext_wait_queue *ewp)
 392 {
 393         struct ext_wait_queue *walk;
 394
 395         ewp->task = current;
 396
 397         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
 398                 if (walk->task->static_prio <= current->static_prio) {
 399                         list_add_tail(&ewp->list, &walk->list);
 400                         return;
 401                 }
 402         }
 403         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
 404 }
 405
 406 /*
 407  * Puts current task to sleep. Caller must hold queue lock. After return
 408  * lock isn't held.
 409  * sr: SEND or RECV
 410  */
 411 static int wq_sleep(struct mqueue_inode_info *info, int sr,
 412                         long timeout, struct ext_wait_queue *ewp)
 413 {
 414         int retval;
 415         signed long time;
 416
 417         wq_add(info, sr, ewp);
 418
 419         for (;;) {
 420                 set_current_state(TASK_INTERRUPTIBLE);
 421
 422                 spin_unlock(&info->lock);
 423                 time = schedule_timeout(timeout);
 424
 425                 while (ewp->state == STATE_PENDING)
 426                         cpu_relax();
 427
 428                 if (ewp->state == STATE_READY) {
 429                         retval = 0;
 430                         goto out;
 431                 }
 432                 spin_lock(&info->lock);
 433                 if (ewp->state == STATE_READY) {
 434                         retval = 0;
 435                         goto out_unlock;
 436                 }
 437                 if (signal_pending(current)) {
 438                         retval = -ERESTARTSYS;
 439                         break;
 440                 }
 441                 if (time == 0) {
 442                         retval = -ETIMEDOUT;
 443                         break;
 444                 }
 445         }
 446         list_del(&ewp->list);
 447 out_unlock:
 448         spin_unlock(&info->lock);
 449 out:
 450         return retval;
 451 }
 452
 453 /*
 454  * Returns waiting task that should be serviced first or NULL if none exists
 455  */
 456 static struct ext_wait_queue *wq_get_first_waiter(
 457                 struct mqueue_inode_info *info, int sr)
 458 {
 459         struct list_head *ptr;
 460
 461         ptr = info->e_wait_q[sr].list.prev;
 462         if (ptr == &info->e_wait_q[sr].list)
 463                 return NULL;
 464         return list_entry(ptr, struct ext_wait_queue, list);
 465 }
 466
 467 /* Auxiliary functions to manipulate messages' list */
 468 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
 469 {
 470         int k;
 471
 472         k = info->attr.mq_curmsgs - 1;
 473         while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
 474                 info->messages[k + 1] = info->messages[k];
 475                 k--;
 476         }
 477         info->attr.mq_curmsgs++;
 478         info->qsize += ptr->m_ts;
 479         info->messages[k + 1] = ptr;
 480 }
 481
 482 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
 483 {
 484         info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
 485         return info->messages[info->attr.mq_curmsgs];
 486 }
 487
 488 static inline void set_cookie(struct sk_buff *skb, char code)
 489 {
 490         ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
 491 }
 492
 493 /*
 494  * The next function is only to split too long sys_mq_timedsend
 495  */
 496 static void __do_notify(struct mqueue_inode_info *info)
 497 {
 498         /* notification
 499          * invoked when there is registered process and there isn't process
 500          * waiting synchronously for message AND state of queue changed from
 501          * empty to not empty. Here we are sure that no one is waiting
 502          * synchronously. */
 503         if (info->notify_owner &&
 504             info->attr.mq_curmsgs == 1) {
 505                 struct siginfo sig_i;
 506                 switch (info->notify.sigev_notify) {
 507                 case SIGEV_NONE:
 508                         break;
 509                 case SIGEV_SIGNAL:
 510                         /* sends signal */
 511
 512                         sig_i.si_signo = info->notify.sigev_signo;
 513                         sig_i.si_errno = 0;
 514                         sig_i.si_code = SI_MESGQ;
 515                         sig_i.si_value = info->notify.sigev_value;
 516                         sig_i.si_pid = current->tgid;
 517                         sig_i.si_uid = current->uid;
 518
 519                         kill_pid_info(info->notify.sigev_signo,
 520                                       &sig_i, info->notify_owner);
 521                         break;
 522                 case SIGEV_THREAD:
 523                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
 524                         netlink_sendskb(info->notify_sock, info->notify_cookie);
 525                         break;
 526                 }
 527                 /* after notification unregisters process */
 528                 put_pid(info->notify_owner);
 529                 info->notify_owner = NULL;
 530         }
 531         wake_up(&info->wait_q);
 532 }
 533
 534 static long prepare_timeout(const struct timespec __user *u_arg)
 535 {
 536         struct timespec ts, nowts;
 537         long timeout;
 538
 539         if (u_arg) {
 540                 if (unlikely(copy_from_user(&ts, u_arg,
 541                                         sizeof(struct timespec))))
 542                         return -EFAULT;
 543
 544                 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0
 545                         || ts.tv_nsec >= NSEC_PER_SEC))
 546                         return -EINVAL;
 547                 nowts = CURRENT_TIME;
 548                 /* first subtract as jiffies can't be too big */
 549                 ts.tv_sec -= nowts.tv_sec;
 550                 if (ts.tv_nsec < nowts.tv_nsec) {
 551                         ts.tv_nsec += NSEC_PER_SEC;
 552                         ts.tv_sec--;
 553                 }
 554                 ts.tv_nsec -= nowts.tv_nsec;
 555                 if (ts.tv_sec < 0)
 556                         return 0;
 557
 558                 timeout = timespec_to_jiffies(&ts) + 1;
 559         } else
 560                 return MAX_SCHEDULE_TIMEOUT;
 561
 562         return timeout;
 563 }
 564
 565 static void remove_notification(struct mqueue_inode_info *info)
 566 {
 567         if (info->notify_owner != NULL &&
 568             info->notify.sigev_notify == SIGEV_THREAD) {
 569                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
 570                 netlink_sendskb(info->notify_sock, info->notify_cookie);
 571         }
 572         put_pid(info->notify_owner);
 573         info->notify_owner = NULL;
 574 }
 575
 576 static int mq_attr_ok(struct mq_attr *attr)
 577 {
 578         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
 579                 return 0;
 580         if (capable(CAP_SYS_RESOURCE)) {
 581                 if (attr->mq_maxmsg > HARD_MSGMAX)
 582                         return 0;
 583         } else {
 584                 if (attr->mq_maxmsg > msg_max ||
 585                                 attr->mq_msgsize > msgsize_max)
 586                         return 0;
 587         }
 588         /* check for overflow */
 589         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
 590                 return 0;
 591         if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
 592             (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
 593             (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
 594                 return 0;
 595         return 1;
 596 }
 597
 598 /*
 599  * Invoked when creating a new queue via sys_mq_open
 600  */
 601 static struct file *do_create(struct dentry *dir, struct dentry *dentry,
 602                         int oflag, mode_t mode, struct mq_attr __user *u_attr)
 603 {
 604         struct mq_attr attr;
 605         int ret;
 606
 607         if (u_attr) {
 608                 ret = -EFAULT;
 609                 if (copy_from_user(&attr, u_attr, sizeof(attr)))
 610                         goto out;
 611                 ret = -EINVAL;
 612                 if (!mq_attr_ok(&attr))
 613                         goto out;
 614                 /* store for use during create */
 615                 dentry->d_fsdata = &attr;
 616         }
 617
 618         mode &= ~current->fs->umask;
 619         ret = vfs_create(dir->d_inode, dentry, mode, NULL);
 620         dentry->d_fsdata = NULL;
 621         if (ret)
 622                 goto out;
 623
 624         return dentry_open(dentry, mqueue_mnt, oflag);
 625
 626 out:
 627         dput(dentry);
 628         mntput(mqueue_mnt);
 629         return ERR_PTR(ret);
 630 }
 631
 632 /* Opens existing queue */
 633 static struct file *do_open(struct dentry *dentry, int oflag)
 634 {
 635 static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
 636                                         MAY_READ | MAY_WRITE };
 637
 638         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
 639                 dput(dentry);
 640                 mntput(mqueue_mnt);
 641                 return ERR_PTR(-EINVAL);
 642         }
 643
 644         if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) {
 645                 dput(dentry);
 646                 mntput(mqueue_mnt);
 647                 return ERR_PTR(-EACCES);
 648         }
 649
 650         return dentry_open(dentry, mqueue_mnt, oflag);
 651 }
 652
 653 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
 654                                 struct mq_attr __user *u_attr)
 655 {
 656         struct dentry *dentry;
 657         struct file *filp;
 658         char *name;
 659         int fd, error;
 660
 661         error = audit_mq_open(oflag, mode, u_attr);
 662         if (error != 0)
 663                 return error;
 664
 665         if (IS_ERR(name = getname(u_name)))
 666                 return PTR_ERR(name);
 667
 668         fd = get_unused_fd();
 669         if (fd < 0)
 670                 goto out_putname;
 671
 672         mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
 673         dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
 674         if (IS_ERR(dentry)) {
 675                 error = PTR_ERR(dentry);
 676                 goto out_err;
 677         }
 678         mntget(mqueue_mnt);
 679
 680         if (oflag & O_CREAT) {
 681                 if (dentry->d_inode) {  /* entry already exists */
 682                         audit_inode(name, dentry->d_inode);
 683                         error = -EEXIST;
 684                         if (oflag & O_EXCL)
 685                                 goto out;
 686                         filp = do_open(dentry, oflag);
 687                 } else {
 688                         filp = do_create(mqueue_mnt->mnt_root, dentry,
 689                                                 oflag, mode, u_attr);
 690                 }
 691         } else {
 692                 error = -ENOENT;
 693                 if (!dentry->d_inode)
 694                         goto out;
 695                 audit_inode(name, dentry->d_inode);
 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_nested(&mqueue_mnt->mnt_root->d_inode->i_mutex,
 734                         I_MUTEX_PARENT);
 735         dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
 736         if (IS_ERR(dentry)) {
 737                 err = PTR_ERR(dentry);
 738                 goto out_unlock;
 739         }
 740
 741         if (!dentry->d_inode) {
 742                 err = -ENOENT;
 743                 goto out_err;
 744         }
 745
 746         inode = dentry->d_inode;
 747         if (inode)
 748                 atomic_inc(&inode->i_count);
 749
 750         err = vfs_unlink(dentry->d_parent->d_inode, dentry);
 751 out_err:
 752         dput(dentry);
 753
 754 out_unlock:
 755         mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
 756         putname(name);
 757         if (inode)
 758                 iput(inode);
 759
 760         return err;
 761 }
 762
 763 /* Pipelined send and receive functions.
 764  *
 765  * If a receiver finds no waiting message, then it registers itself in the
 766  * list of waiting receivers. A sender checks that list before adding the new
 767  * message into the message array. If there is a waiting receiver, then it
 768  * bypasses the message array and directly hands the message over to the
 769  * receiver.
 770  * The receiver accepts the message and returns without grabbing the queue
 771  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
 772  * are necessary. The same algorithm is used for sysv semaphores, see
 773  * ipc/sem.c for more details.
 774  *
 775  * The same algorithm is used for senders.
 776  */
 777
 778 /* pipelined_send() - send a message directly to the task waiting in
 779  * sys_mq_timedreceive() (without inserting message into a queue).
 780  */
 781 static inline void pipelined_send(struct mqueue_inode_info *info,
 782                                   struct msg_msg *message,
 783                                   struct ext_wait_queue *receiver)
 784 {
 785         receiver->msg = message;
 786         list_del(&receiver->list);
 787         receiver->state = STATE_PENDING;
 788         wake_up_process(receiver->task);
 789         smp_wmb();
 790         receiver->state = STATE_READY;
 791 }
 792
 793 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
 794  * gets its message and put to the queue (we have one free place for sure). */
 795 static inline void pipelined_receive(struct mqueue_inode_info *info)
 796 {
 797         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
 798
 799         if (!sender) {
 800                 /* for poll */
 801                 wake_up_interruptible(&info->wait_q);
 802                 return;
 803         }
 804         msg_insert(sender->msg, info);
 805         list_del(&sender->list);
 806         sender->state = STATE_PENDING;
 807         wake_up_process(sender->task);
 808         smp_wmb();
 809         sender->state = STATE_READY;
 810 }
 811
 812 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
 813         size_t msg_len, unsigned int msg_prio,
 814         const struct timespec __user *u_abs_timeout)
 815 {
 816         struct file *filp;
 817         struct inode *inode;
 818         struct ext_wait_queue wait;
 819         struct ext_wait_queue *receiver;
 820         struct msg_msg *msg_ptr;
 821         struct mqueue_inode_info *info;
 822         long timeout;
 823         int ret;
 824
 825         ret = audit_mq_timedsend(mqdes, msg_len, msg_prio, u_abs_timeout);
 826         if (ret != 0)
 827                 return ret;
 828
 829         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
 830                 return -EINVAL;
 831
 832         timeout = prepare_timeout(u_abs_timeout);
 833
 834         ret = -EBADF;
 835         filp = fget(mqdes);
 836         if (unlikely(!filp))
 837                 goto out;
 838
 839         inode = filp->f_path.dentry->d_inode;
 840         if (unlikely(filp->f_op != &mqueue_file_operations))
 841                 goto out_fput;
 842         info = MQUEUE_I(inode);
 843         audit_inode(NULL, inode);
 844
 845         if (unlikely(!(filp->f_mode & FMODE_WRITE)))
 846                 goto out_fput;
 847
 848         if (unlikely(msg_len > info->attr.mq_msgsize)) {
 849                 ret = -EMSGSIZE;
 850                 goto out_fput;
 851         }
 852
 853         /* First try to allocate memory, before doing anything with
 854          * existing queues. */
 855         msg_ptr = load_msg(u_msg_ptr, msg_len);
 856         if (IS_ERR(msg_ptr)) {
 857                 ret = PTR_ERR(msg_ptr);
 858                 goto out_fput;
 859         }
 860         msg_ptr->m_ts = msg_len;
 861         msg_ptr->m_type = msg_prio;
 862
 863         spin_lock(&info->lock);
 864
 865         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
 866                 if (filp->f_flags & O_NONBLOCK) {
 867                         spin_unlock(&info->lock);
 868                         ret = -EAGAIN;
 869                 } else if (unlikely(timeout < 0)) {
 870                         spin_unlock(&info->lock);
 871                         ret = timeout;
 872                 } else {
 873                         wait.task = current;
 874                         wait.msg = (void *) msg_ptr;
 875                         wait.state = STATE_NONE;
 876                         ret = wq_sleep(info, SEND, timeout, &wait);
 877                 }
 878                 if (ret < 0)
 879                         free_msg(msg_ptr);
 880         } else {
 881                 receiver = wq_get_first_waiter(info, RECV);
 882                 if (receiver) {
 883                         pipelined_send(info, msg_ptr, receiver);
 884                 } else {
 885                         /* adds message to the queue */
 886                         msg_insert(msg_ptr, info);
 887                         __do_notify(info);
 888                 }
 889                 inode->i_atime = inode->i_mtime = inode->i_ctime =
 890                                 CURRENT_TIME;
 891                 spin_unlock(&info->lock);
 892                 ret = 0;
 893         }
 894 out_fput:
 895         fput(filp);
 896 out:
 897         return ret;
 898 }
 899
 900 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
 901         size_t msg_len, unsigned int __user *u_msg_prio,
 902         const struct timespec __user *u_abs_timeout)
 903 {
 904         long timeout;
 905         ssize_t ret;
 906         struct msg_msg *msg_ptr;
 907         struct file *filp;
 908         struct inode *inode;
 909         struct mqueue_inode_info *info;
 910         struct ext_wait_queue wait;
 911
 912         ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout);
 913         if (ret != 0)
 914                 return ret;
 915
 916         timeout = prepare_timeout(u_abs_timeout);
 917
 918         ret = -EBADF;
 919         filp = fget(mqdes);
 920         if (unlikely(!filp))
 921                 goto out;
 922
 923         inode = filp->f_path.dentry->d_inode;
 924         if (unlikely(filp->f_op != &mqueue_file_operations))
 925                 goto out_fput;
 926         info = MQUEUE_I(inode);
 927         audit_inode(NULL, inode);
 928
 929         if (unlikely(!(filp->f_mode & FMODE_READ)))
 930                 goto out_fput;
 931
 932         /* checks if buffer is big enough */
 933         if (unlikely(msg_len < info->attr.mq_msgsize)) {
 934                 ret = -EMSGSIZE;
 935                 goto out_fput;
 936         }
 937
 938         spin_lock(&info->lock);
 939         if (info->attr.mq_curmsgs == 0) {
 940                 if (filp->f_flags & O_NONBLOCK) {
 941                         spin_unlock(&info->lock);
 942                         ret = -EAGAIN;
 943                         msg_ptr = NULL;
 944                 } else if (unlikely(timeout < 0)) {
 945                         spin_unlock(&info->lock);
 946                         ret = timeout;
 947                         msg_ptr = NULL;
 948                 } else {
 949                         wait.task = current;
 950                         wait.state = STATE_NONE;
 951                         ret = wq_sleep(info, RECV, timeout, &wait);
 952                         msg_ptr = wait.msg;
 953                 }
 954         } else {
 955                 msg_ptr = msg_get(info);
 956
 957                 inode->i_atime = inode->i_mtime = inode->i_ctime =
 958                                 CURRENT_TIME;
 959
 960                 /* There is now free space in queue. */
 961                 pipelined_receive(info);
 962                 spin_unlock(&info->lock);
 963                 ret = 0;
 964         }
 965         if (ret == 0) {
 966                 ret = msg_ptr->m_ts;
 967
 968                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
 969                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
 970                         ret = -EFAULT;
 971                 }
 972                 free_msg(msg_ptr);
 973         }
 974 out_fput:
 975         fput(filp);
 976 out:
 977         return ret;
 978 }
 979
 980 /*
 981  * Notes: the case when user wants us to deregister (with NULL as pointer)
 982  * and he isn't currently owner of notification, will be silently discarded.
 983  * It isn't explicitly defined in the POSIX.
 984  */
 985 asmlinkage long sys_mq_notify(mqd_t mqdes,
 986                                 const struct sigevent __user *u_notification)
 987 {
 988         int ret;
 989         struct file *filp;
 990         struct sock *sock;
 991         struct inode *inode;
 992         struct sigevent notification;
 993         struct mqueue_inode_info *info;
 994         struct sk_buff *nc;
 995
 996         ret = audit_mq_notify(mqdes, u_notification);
 997         if (ret != 0)
 998                 return ret;
 999
1000         nc = NULL;
1001         sock = NULL;
1002         if (u_notification != NULL) {
1003                 if (copy_from_user(&notification, u_notification,
1004                                         sizeof(struct sigevent)))
1005                         return -EFAULT;
1006
1007                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1008                              notification.sigev_notify != SIGEV_SIGNAL &&
1009                              notification.sigev_notify != SIGEV_THREAD))
1010                         return -EINVAL;
1011                 if (notification.sigev_notify == SIGEV_SIGNAL &&
1012                         !valid_signal(notification.sigev_signo)) {
1013                         return -EINVAL;
1014                 }
1015                 if (notification.sigev_notify == SIGEV_THREAD) {
1016                         /* create the notify skb */
1017                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1018                         ret = -ENOMEM;
1019                         if (!nc)
1020                                 goto out;
1021                         ret = -EFAULT;
1022                         if (copy_from_user(nc->data,
1023                                         notification.sigev_value.sival_ptr,
1024                                         NOTIFY_COOKIE_LEN)) {
1025                                 goto out;
1026                         }
1027
1028                         /* TODO: add a header? */
1029                         skb_put(nc, NOTIFY_COOKIE_LEN);
1030                         /* and attach it to the socket */
1031 retry:
1032                         filp = fget(notification.sigev_signo);
1033                         ret = -EBADF;
1034                         if (!filp)
1035                                 goto out;
1036                         sock = netlink_getsockbyfilp(filp);
1037                         fput(filp);
1038                         if (IS_ERR(sock)) {
1039                                 ret = PTR_ERR(sock);
1040                                 sock = NULL;
1041                                 goto out;
1042                         }
1043
1044                         ret = netlink_attachskb(sock, nc, 0,
1045                                         MAX_SCHEDULE_TIMEOUT, NULL);
1046                         if (ret == 1)
1047                                 goto retry;
1048                         if (ret) {
1049                                 sock = NULL;
1050                                 nc = NULL;
1051                                 goto out;
1052                         }
1053                 }
1054         }
1055
1056         ret = -EBADF;
1057         filp = fget(mqdes);
1058         if (!filp)
1059                 goto out;
1060
1061         inode = filp->f_path.dentry->d_inode;
1062         if (unlikely(filp->f_op != &mqueue_file_operations))
1063                 goto out_fput;
1064         info = MQUEUE_I(inode);
1065
1066         ret = 0;
1067         spin_lock(&info->lock);
1068         if (u_notification == NULL) {
1069                 if (info->notify_owner == task_tgid(current)) {
1070                         remove_notification(info);
1071                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1072                 }
1073         } else if (info->notify_owner != NULL) {
1074                 ret = -EBUSY;
1075         } else {
1076                 switch (notification.sigev_notify) {
1077                 case SIGEV_NONE:
1078                         info->notify.sigev_notify = SIGEV_NONE;
1079                         break;
1080                 case SIGEV_THREAD:
1081                         info->notify_sock = sock;
1082                         info->notify_cookie = nc;
1083                         sock = NULL;
1084                         nc = NULL;
1085                         info->notify.sigev_notify = SIGEV_THREAD;
1086                         break;
1087                 case SIGEV_SIGNAL:
1088                         info->notify.sigev_signo = notification.sigev_signo;
1089                         info->notify.sigev_value = notification.sigev_value;
1090                         info->notify.sigev_notify = SIGEV_SIGNAL;
1091                         break;
1092                 }
1093
1094                 info->notify_owner = get_pid(task_tgid(current));
1095                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1096         }
1097         spin_unlock(&info->lock);
1098 out_fput:
1099         fput(filp);
1100 out:
1101         if (sock) {
1102                 netlink_detachskb(sock, nc);
1103         } else if (nc) {
1104                 dev_kfree_skb(nc);
1105         }
1106         return ret;
1107 }
1108
1109 asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1110                         const struct mq_attr __user *u_mqstat,
1111                         struct mq_attr __user *u_omqstat)
1112 {
1113         int ret;
1114         struct mq_attr mqstat, omqstat;
1115         struct file *filp;
1116         struct inode *inode;
1117         struct mqueue_inode_info *info;
1118
1119         if (u_mqstat != NULL) {
1120                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1121                         return -EFAULT;
1122                 if (mqstat.mq_flags & (~O_NONBLOCK))
1123                         return -EINVAL;
1124         }
1125
1126         ret = -EBADF;
1127         filp = fget(mqdes);
1128         if (!filp)
1129                 goto out;
1130
1131         inode = filp->f_path.dentry->d_inode;
1132         if (unlikely(filp->f_op != &mqueue_file_operations))
1133                 goto out_fput;
1134         info = MQUEUE_I(inode);
1135
1136         spin_lock(&info->lock);
1137
1138         omqstat = info->attr;
1139         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1140         if (u_mqstat) {
1141                 ret = audit_mq_getsetattr(mqdes, &mqstat);
1142                 if (ret != 0)
1143                         goto out;
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                 .ctl_name       = CTL_QUEUESMAX,
1200                 .procname       = "queues_max",
1201                 .data           = &queues_max,
1202                 .maxlen         = sizeof(int),
1203                 .mode           = 0644,
1204                 .proc_handler   = &proc_dointvec,
1205         },
1206         {
1207                 .ctl_name       = CTL_MSGMAX,
1208                 .procname       = "msg_max",
1209                 .data           = &msg_max,
1210                 .maxlen         = sizeof(int),
1211                 .mode           = 0644,
1212                 .proc_handler   = &proc_dointvec_minmax,
1213                 .extra1         = &msg_max_limit_min,
1214                 .extra2         = &msg_max_limit_max,
1215         },
1216         {
1217                 .ctl_name       = CTL_MSGSIZEMAX,
1218                 .procname       = "msgsize_max",
1219                 .data           = &msgsize_max,
1220                 .maxlen         = sizeof(int),
1221                 .mode           = 0644,
1222                 .proc_handler   = &proc_dointvec_minmax,
1223                 .extra1         = &msg_maxsize_limit_min,
1224                 .extra2         = &msg_maxsize_limit_max,
1225         },
1226         { .ctl_name = 0 }
1227 };
1228
1229 static ctl_table mq_sysctl_dir[] = {
1230         {
1231                 .ctl_name       = FS_MQUEUE,
1232                 .procname       = "mqueue",
1233                 .mode           = 0555,
1234                 .child          = mq_sysctls,
1235         },
1236         { .ctl_name = 0 }
1237 };
1238
1239 static ctl_table mq_sysctl_root[] = {
1240         {
1241                 .ctl_name       = CTL_FS,
1242                 .procname       = "fs",
1243                 .mode           = 0555,
1244                 .child          = mq_sysctl_dir,
1245         },
1246         { .ctl_name = 0 }
1247 };
1248
1249 static int __init init_mqueue_fs(void)
1250 {
1251         int error;
1252
1253         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1254                                 sizeof(struct mqueue_inode_info), 0,
1255                                 SLAB_HWCACHE_ALIGN, init_once);
1256         if (mqueue_inode_cachep == NULL)
1257                 return -ENOMEM;
1258
1259         /* ignore failues - they are not fatal */
1260         mq_sysctl_table = register_sysctl_table(mq_sysctl_root);
1261
1262         error = register_filesystem(&mqueue_fs_type);
1263         if (error)
1264                 goto out_sysctl;
1265
1266         if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1267                 error = PTR_ERR(mqueue_mnt);
1268                 goto out_filesystem;
1269         }
1270
1271         /* internal initialization - not common for vfs */
1272         queues_count = 0;
1273         spin_lock_init(&mq_lock);
1274
1275         return 0;
1276
1277 out_filesystem:
1278         unregister_filesystem(&mqueue_fs_type);
1279 out_sysctl:
1280         if (mq_sysctl_table)
1281                 unregister_sysctl_table(mq_sysctl_table);
1282         kmem_cache_destroy(mqueue_inode_cachep);
1283         return error;
1284 }
1285
1286 __initcall(init_mqueue_fs);