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         if (flags & SLAB_CTOR_CONSTRUCTOR)
 219                 inode_init_once(&p->vfs_inode);
 220 }
 221
 222 static struct inode *mqueue_alloc_inode(struct super_block *sb)
 223 {
 224         struct mqueue_inode_info *ei;
 225
 226         ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
 227         if (!ei)
 228                 return NULL;
 229         return &ei->vfs_inode;
 230 }
 231
 232 static void mqueue_destroy_inode(struct inode *inode)
 233 {
 234         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
 235 }
 236
 237 static void mqueue_delete_inode(struct inode *inode)
 238 {
 239         struct mqueue_inode_info *info;
 240         struct user_struct *user;
 241         unsigned long mq_bytes;
 242         int i;
 243
 244         if (S_ISDIR(inode->i_mode)) {
 245                 clear_inode(inode);
 246                 return;
 247         }
 248         info = MQUEUE_I(inode);
 249         spin_lock(&info->lock);
 250         for (i = 0; i < info->attr.mq_curmsgs; i++)
 251                 free_msg(info->messages[i]);
 252         kfree(info->messages);
 253         spin_unlock(&info->lock);
 254
 255         clear_inode(inode);
 256
 257         mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
 258                    (info->attr.mq_maxmsg * info->attr.mq_msgsize));
 259         user = info->user;
 260         if (user) {
 261                 spin_lock(&mq_lock);
 262                 user->mq_bytes -= mq_bytes;
 263                 queues_count--;
 264                 spin_unlock(&mq_lock);
 265                 free_uid(user);
 266         }
 267 }
 268
 269 static int mqueue_create(struct inode *dir, struct dentry *dentry,
 270                                 int mode, struct nameidata *nd)
 271 {
 272         struct inode *inode;
 273         struct mq_attr *attr = dentry->d_fsdata;
 274         int error;
 275
 276         spin_lock(&mq_lock);
 277         if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
 278                 error = -ENOSPC;
 279                 goto out_lock;
 280         }
 281         queues_count++;
 282         spin_unlock(&mq_lock);
 283
 284         inode = mqueue_get_inode(dir->i_sb, mode, attr);
 285         if (!inode) {
 286                 error = -ENOMEM;
 287                 spin_lock(&mq_lock);
 288                 queues_count--;
 289                 goto out_lock;
 290         }
 291
 292         dir->i_size += DIRENT_SIZE;
 293         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 294
 295         d_instantiate(dentry, inode);
 296         dget(dentry);
 297         return 0;
 298 out_lock:
 299         spin_unlock(&mq_lock);
 300         return error;
 301 }
 302
 303 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
 304 {
 305         struct inode *inode = dentry->d_inode;
 306
 307         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 308         dir->i_size -= DIRENT_SIZE;
 309         drop_nlink(inode);
 310         dput(dentry);
 311         return 0;
 312 }
 313
 314 /*
 315 *       This is routine for system read from queue file.
 316 *       To avoid mess with doing here some sort of mq_receive we allow
 317 *       to read only queue size & notification info (the only values
 318 *       that are interesting from user point of view and aren't accessible
 319 *       through std routines)
 320 */
 321 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
 322                                 size_t count, loff_t * off)
 323 {
 324         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 325         char buffer[FILENT_SIZE];
 326         size_t slen;
 327         loff_t o;
 328
 329         if (!count)
 330                 return 0;
 331
 332         spin_lock(&info->lock);
 333         snprintf(buffer, sizeof(buffer),
 334                         "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
 335                         info->qsize,
 336                         info->notify_owner ? info->notify.sigev_notify : 0,
 337                         (info->notify_owner &&
 338                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
 339                                 info->notify.sigev_signo : 0,
 340                         pid_nr(info->notify_owner));
 341         spin_unlock(&info->lock);
 342         buffer[sizeof(buffer)-1] = '\0';
 343         slen = strlen(buffer)+1;
 344
 345         o = *off;
 346         if (o > slen)
 347                 return 0;
 348
 349         if (o + count > slen)
 350                 count = slen - o;
 351
 352         if (copy_to_user(u_data, buffer + o, count))
 353                 return -EFAULT;
 354
 355         *off = o + count;
 356         filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
 357         return count;
 358 }
 359
 360 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
 361 {
 362         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 363
 364         spin_lock(&info->lock);
 365         if (task_tgid(current) == info->notify_owner)
 366                 remove_notification(info);
 367
 368         spin_unlock(&info->lock);
 369         return 0;
 370 }
 371
 372 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
 373 {
 374         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 375         int retval = 0;
 376
 377         poll_wait(filp, &info->wait_q, poll_tab);
 378
 379         spin_lock(&info->lock);
 380         if (info->attr.mq_curmsgs)
 381                 retval = POLLIN | POLLRDNORM;
 382
 383         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
 384                 retval |= POLLOUT | POLLWRNORM;
 385         spin_unlock(&info->lock);
 386
 387         return retval;
 388 }
 389
 390 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
 391 static void wq_add(struct mqueue_inode_info *info, int sr,
 392                         struct ext_wait_queue *ewp)
 393 {
 394         struct ext_wait_queue *walk;
 395
 396         ewp->task = current;
 397
 398         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
 399                 if (walk->task->static_prio <= current->static_prio) {
 400                         list_add_tail(&ewp->list, &walk->list);
 401                         return;
 402                 }
 403         }
 404         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
 405 }
 406
 407 /*
 408  * Puts current task to sleep. Caller must hold queue lock. After return
 409  * lock isn't held.
 410  * sr: SEND or RECV
 411  */
 412 static int wq_sleep(struct mqueue_inode_info *info, int sr,
 413                         long timeout, struct ext_wait_queue *ewp)
 414 {
 415         int retval;
 416         signed long time;
 417
 418         wq_add(info, sr, ewp);
 419
 420         for (;;) {
 421                 set_current_state(TASK_INTERRUPTIBLE);
 422
 423                 spin_unlock(&info->lock);
 424                 time = schedule_timeout(timeout);
 425
 426                 while (ewp->state == STATE_PENDING)
 427                         cpu_relax();
 428
 429                 if (ewp->state == STATE_READY) {
 430                         retval = 0;
 431                         goto out;
 432                 }
 433                 spin_lock(&info->lock);
 434                 if (ewp->state == STATE_READY) {
 435                         retval = 0;
 436                         goto out_unlock;
 437                 }
 438                 if (signal_pending(current)) {
 439                         retval = -ERESTARTSYS;
 440                         break;
 441                 }
 442                 if (time == 0) {
 443                         retval = -ETIMEDOUT;
 444                         break;
 445                 }
 446         }
 447         list_del(&ewp->list);
 448 out_unlock:
 449         spin_unlock(&info->lock);
 450 out:
 451         return retval;
 452 }
 453
 454 /*
 455  * Returns waiting task that should be serviced first or NULL if none exists
 456  */
 457 static struct ext_wait_queue *wq_get_first_waiter(
 458                 struct mqueue_inode_info *info, int sr)
 459 {
 460         struct list_head *ptr;
 461
 462         ptr = info->e_wait_q[sr].list.prev;
 463         if (ptr == &info->e_wait_q[sr].list)
 464                 return NULL;
 465         return list_entry(ptr, struct ext_wait_queue, list);
 466 }
 467
 468 /* Auxiliary functions to manipulate messages' list */
 469 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
 470 {
 471         int k;
 472
 473         k = info->attr.mq_curmsgs - 1;
 474         while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
 475                 info->messages[k + 1] = info->messages[k];
 476                 k--;
 477         }
 478         info->attr.mq_curmsgs++;
 479         info->qsize += ptr->m_ts;
 480         info->messages[k + 1] = ptr;
 481 }
 482
 483 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
 484 {
 485         info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
 486         return info->messages[info->attr.mq_curmsgs];
 487 }
 488
 489 static inline void set_cookie(struct sk_buff *skb, char code)
 490 {
 491         ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
 492 }
 493
 494 /*
 495  * The next function is only to split too long sys_mq_timedsend
 496  */
 497 static void __do_notify(struct mqueue_inode_info *info)
 498 {
 499         /* notification
 500          * invoked when there is registered process and there isn't process
 501          * waiting synchronously for message AND state of queue changed from
 502          * empty to not empty. Here we are sure that no one is waiting
 503          * synchronously. */
 504         if (info->notify_owner &&
 505             info->attr.mq_curmsgs == 1) {
 506                 struct siginfo sig_i;
 507                 switch (info->notify.sigev_notify) {
 508                 case SIGEV_NONE:
 509                         break;
 510                 case SIGEV_SIGNAL:
 511                         /* sends signal */
 512
 513                         sig_i.si_signo = info->notify.sigev_signo;
 514                         sig_i.si_errno = 0;
 515                         sig_i.si_code = SI_MESGQ;
 516                         sig_i.si_value = info->notify.sigev_value;
 517                         sig_i.si_pid = current->tgid;
 518                         sig_i.si_uid = current->uid;
 519
 520                         kill_pid_info(info->notify.sigev_signo,
 521                                       &sig_i, info->notify_owner);
 522                         break;
 523                 case SIGEV_THREAD:
 524                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
 525                         netlink_sendskb(info->notify_sock,
 526                                         info->notify_cookie, 0);
 527                         break;
 528                 }
 529                 /* after notification unregisters process */
 530                 put_pid(info->notify_owner);
 531                 info->notify_owner = NULL;
 532         }
 533         wake_up(&info->wait_q);
 534 }
 535
 536 static long prepare_timeout(const struct timespec __user *u_arg)
 537 {
 538         struct timespec ts, nowts;
 539         long timeout;
 540
 541         if (u_arg) {
 542                 if (unlikely(copy_from_user(&ts, u_arg,
 543                                         sizeof(struct timespec))))
 544                         return -EFAULT;
 545
 546                 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0
 547                         || ts.tv_nsec >= NSEC_PER_SEC))
 548                         return -EINVAL;
 549                 nowts = CURRENT_TIME;
 550                 /* first subtract as jiffies can't be too big */
 551                 ts.tv_sec -= nowts.tv_sec;
 552                 if (ts.tv_nsec < nowts.tv_nsec) {
 553                         ts.tv_nsec += NSEC_PER_SEC;
 554                         ts.tv_sec--;
 555                 }
 556                 ts.tv_nsec -= nowts.tv_nsec;
 557                 if (ts.tv_sec < 0)
 558                         return 0;
 559
 560                 timeout = timespec_to_jiffies(&ts) + 1;
 561         } else
 562                 return MAX_SCHEDULE_TIMEOUT;
 563
 564         return timeout;
 565 }
 566
 567 static void remove_notification(struct mqueue_inode_info *info)
 568 {
 569         if (info->notify_owner != NULL &&
 570             info->notify.sigev_notify == SIGEV_THREAD) {
 571                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
 572                 netlink_sendskb(info->notify_sock, info->notify_cookie, 0);
 573         }
 574         put_pid(info->notify_owner);
 575         info->notify_owner = NULL;
 576 }
 577
 578 static int mq_attr_ok(struct mq_attr *attr)
 579 {
 580         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
 581                 return 0;
 582         if (capable(CAP_SYS_RESOURCE)) {
 583                 if (attr->mq_maxmsg > HARD_MSGMAX)
 584                         return 0;
 585         } else {
 586                 if (attr->mq_maxmsg > msg_max ||
 587                                 attr->mq_msgsize > msgsize_max)
 588                         return 0;
 589         }
 590         /* check for overflow */
 591         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
 592                 return 0;
 593         if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
 594             (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
 595             (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
 596                 return 0;
 597         return 1;
 598 }
 599
 600 /*
 601  * Invoked when creating a new queue via sys_mq_open
 602  */
 603 static struct file *do_create(struct dentry *dir, struct dentry *dentry,
 604                         int oflag, mode_t mode, struct mq_attr __user *u_attr)
 605 {
 606         struct mq_attr attr;
 607         int ret;
 608
 609         if (u_attr) {
 610                 ret = -EFAULT;
 611                 if (copy_from_user(&attr, u_attr, sizeof(attr)))
 612                         goto out;
 613                 ret = -EINVAL;
 614                 if (!mq_attr_ok(&attr))
 615                         goto out;
 616                 /* store for use during create */
 617                 dentry->d_fsdata = &attr;
 618         }
 619
 620         mode &= ~current->fs->umask;
 621         ret = vfs_create(dir->d_inode, dentry, mode, NULL);
 622         dentry->d_fsdata = NULL;
 623         if (ret)
 624                 goto out;
 625
 626         return dentry_open(dentry, mqueue_mnt, oflag);
 627
 628 out:
 629         dput(dentry);
 630         mntput(mqueue_mnt);
 631         return ERR_PTR(ret);
 632 }
 633
 634 /* Opens existing queue */
 635 static struct file *do_open(struct dentry *dentry, int oflag)
 636 {
 637 static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
 638                                         MAY_READ | MAY_WRITE };
 639
 640         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
 641                 dput(dentry);
 642                 mntput(mqueue_mnt);
 643                 return ERR_PTR(-EINVAL);
 644         }
 645
 646         if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) {
 647                 dput(dentry);
 648                 mntput(mqueue_mnt);
 649                 return ERR_PTR(-EACCES);
 650         }
 651
 652         return dentry_open(dentry, mqueue_mnt, oflag);
 653 }
 654
 655 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
 656                                 struct mq_attr __user *u_attr)
 657 {
 658         struct dentry *dentry;
 659         struct file *filp;
 660         char *name;
 661         int fd, error;
 662
 663         error = audit_mq_open(oflag, mode, u_attr);
 664         if (error != 0)
 665                 return error;
 666
 667         if (IS_ERR(name = getname(u_name)))
 668                 return PTR_ERR(name);
 669
 670         fd = get_unused_fd();
 671         if (fd < 0)
 672                 goto out_putname;
 673
 674         mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
 675         dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
 676         if (IS_ERR(dentry)) {
 677                 error = PTR_ERR(dentry);
 678                 goto out_err;
 679         }
 680         mntget(mqueue_mnt);
 681
 682         if (oflag & O_CREAT) {
 683                 if (dentry->d_inode) {  /* entry already exists */
 684                         audit_inode(name, dentry->d_inode);
 685                         error = -EEXIST;
 686                         if (oflag & O_EXCL)
 687                                 goto out;
 688                         filp = do_open(dentry, oflag);
 689                 } else {
 690                         filp = do_create(mqueue_mnt->mnt_root, dentry,
 691                                                 oflag, mode, u_attr);
 692                 }
 693         } else {
 694                 error = -ENOENT;
 695                 if (!dentry->d_inode)
 696                         goto out;
 697                 audit_inode(name, dentry->d_inode);
 698                 filp = do_open(dentry, oflag);
 699         }
 700
 701         if (IS_ERR(filp)) {
 702                 error = PTR_ERR(filp);
 703                 goto out_putfd;
 704         }
 705
 706         set_close_on_exec(fd, 1);
 707         fd_install(fd, filp);
 708         goto out_upsem;
 709
 710 out:
 711         dput(dentry);
 712         mntput(mqueue_mnt);
 713 out_putfd:
 714         put_unused_fd(fd);
 715 out_err:
 716         fd = error;
 717 out_upsem:
 718         mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
 719 out_putname:
 720         putname(name);
 721         return fd;
 722 }
 723
 724 asmlinkage long sys_mq_unlink(const char __user *u_name)
 725 {
 726         int err;
 727         char *name;
 728         struct dentry *dentry;
 729         struct inode *inode = NULL;
 730
 731         name = getname(u_name);
 732         if (IS_ERR(name))
 733                 return PTR_ERR(name);
 734
 735         mutex_lock_nested(&mqueue_mnt->mnt_root->d_inode->i_mutex,
 736                         I_MUTEX_PARENT);
 737         dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
 738         if (IS_ERR(dentry)) {
 739                 err = PTR_ERR(dentry);
 740                 goto out_unlock;
 741         }
 742
 743         if (!dentry->d_inode) {
 744                 err = -ENOENT;
 745                 goto out_err;
 746         }
 747
 748         inode = dentry->d_inode;
 749         if (inode)
 750                 atomic_inc(&inode->i_count);
 751
 752         err = vfs_unlink(dentry->d_parent->d_inode, dentry);
 753 out_err:
 754         dput(dentry);
 755
 756 out_unlock:
 757         mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
 758         putname(name);
 759         if (inode)
 760                 iput(inode);
 761
 762         return err;
 763 }
 764
 765 /* Pipelined send and receive functions.
 766  *
 767  * If a receiver finds no waiting message, then it registers itself in the
 768  * list of waiting receivers. A sender checks that list before adding the new
 769  * message into the message array. If there is a waiting receiver, then it
 770  * bypasses the message array and directly hands the message over to the
 771  * receiver.
 772  * The receiver accepts the message and returns without grabbing the queue
 773  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
 774  * are necessary. The same algorithm is used for sysv semaphores, see
 775  * ipc/sem.c for more details.
 776  *
 777  * The same algorithm is used for senders.
 778  */
 779
 780 /* pipelined_send() - send a message directly to the task waiting in
 781  * sys_mq_timedreceive() (without inserting message into a queue).
 782  */
 783 static inline void pipelined_send(struct mqueue_inode_info *info,
 784                                   struct msg_msg *message,
 785                                   struct ext_wait_queue *receiver)
 786 {
 787         receiver->msg = message;
 788         list_del(&receiver->list);
 789         receiver->state = STATE_PENDING;
 790         wake_up_process(receiver->task);
 791         smp_wmb();
 792         receiver->state = STATE_READY;
 793 }
 794
 795 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
 796  * gets its message and put to the queue (we have one free place for sure). */
 797 static inline void pipelined_receive(struct mqueue_inode_info *info)
 798 {
 799         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
 800
 801         if (!sender) {
 802                 /* for poll */
 803                 wake_up_interruptible(&info->wait_q);
 804                 return;
 805         }
 806         msg_insert(sender->msg, info);
 807         list_del(&sender->list);
 808         sender->state = STATE_PENDING;
 809         wake_up_process(sender->task);
 810         smp_wmb();
 811         sender->state = STATE_READY;
 812 }
 813
 814 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
 815         size_t msg_len, unsigned int msg_prio,
 816         const struct timespec __user *u_abs_timeout)
 817 {
 818         struct file *filp;
 819         struct inode *inode;
 820         struct ext_wait_queue wait;
 821         struct ext_wait_queue *receiver;
 822         struct msg_msg *msg_ptr;
 823         struct mqueue_inode_info *info;
 824         long timeout;
 825         int ret;
 826
 827         ret = audit_mq_timedsend(mqdes, msg_len, msg_prio, u_abs_timeout);
 828         if (ret != 0)
 829                 return ret;
 830
 831         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
 832                 return -EINVAL;
 833
 834         timeout = prepare_timeout(u_abs_timeout);
 835
 836         ret = -EBADF;
 837         filp = fget(mqdes);
 838         if (unlikely(!filp))
 839                 goto out;
 840
 841         inode = filp->f_path.dentry->d_inode;
 842         if (unlikely(filp->f_op != &mqueue_file_operations))
 843                 goto out_fput;
 844         info = MQUEUE_I(inode);
 845         audit_inode(NULL, inode);
 846
 847         if (unlikely(!(filp->f_mode & FMODE_WRITE)))
 848                 goto out_fput;
 849
 850         if (unlikely(msg_len > info->attr.mq_msgsize)) {
 851                 ret = -EMSGSIZE;
 852                 goto out_fput;
 853         }
 854
 855         /* First try to allocate memory, before doing anything with
 856          * existing queues. */
 857         msg_ptr = load_msg(u_msg_ptr, msg_len);
 858         if (IS_ERR(msg_ptr)) {
 859                 ret = PTR_ERR(msg_ptr);
 860                 goto out_fput;
 861         }
 862         msg_ptr->m_ts = msg_len;
 863         msg_ptr->m_type = msg_prio;
 864
 865         spin_lock(&info->lock);
 866
 867         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
 868                 if (filp->f_flags & O_NONBLOCK) {
 869                         spin_unlock(&info->lock);
 870                         ret = -EAGAIN;
 871                 } else if (unlikely(timeout < 0)) {
 872                         spin_unlock(&info->lock);
 873                         ret = timeout;
 874                 } else {
 875                         wait.task = current;
 876                         wait.msg = (void *) msg_ptr;
 877                         wait.state = STATE_NONE;
 878                         ret = wq_sleep(info, SEND, timeout, &wait);
 879                 }
 880                 if (ret < 0)
 881                         free_msg(msg_ptr);
 882         } else {
 883                 receiver = wq_get_first_waiter(info, RECV);
 884                 if (receiver) {
 885                         pipelined_send(info, msg_ptr, receiver);
 886                 } else {
 887                         /* adds message to the queue */
 888                         msg_insert(msg_ptr, info);
 889                         __do_notify(info);
 890                 }
 891                 inode->i_atime = inode->i_mtime = inode->i_ctime =
 892                                 CURRENT_TIME;
 893                 spin_unlock(&info->lock);
 894                 ret = 0;
 895         }
 896 out_fput:
 897         fput(filp);
 898 out:
 899         return ret;
 900 }
 901
 902 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
 903         size_t msg_len, unsigned int __user *u_msg_prio,
 904         const struct timespec __user *u_abs_timeout)
 905 {
 906         long timeout;
 907         ssize_t ret;
 908         struct msg_msg *msg_ptr;
 909         struct file *filp;
 910         struct inode *inode;
 911         struct mqueue_inode_info *info;
 912         struct ext_wait_queue wait;
 913
 914         ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout);
 915         if (ret != 0)
 916                 return ret;
 917
 918         timeout = prepare_timeout(u_abs_timeout);
 919
 920         ret = -EBADF;
 921         filp = fget(mqdes);
 922         if (unlikely(!filp))
 923                 goto out;
 924
 925         inode = filp->f_path.dentry->d_inode;
 926         if (unlikely(filp->f_op != &mqueue_file_operations))
 927                 goto out_fput;
 928         info = MQUEUE_I(inode);
 929         audit_inode(NULL, inode);
 930
 931         if (unlikely(!(filp->f_mode & FMODE_READ)))
 932                 goto out_fput;
 933
 934         /* checks if buffer is big enough */
 935         if (unlikely(msg_len < info->attr.mq_msgsize)) {
 936                 ret = -EMSGSIZE;
 937                 goto out_fput;
 938         }
 939
 940         spin_lock(&info->lock);
 941         if (info->attr.mq_curmsgs == 0) {
 942                 if (filp->f_flags & O_NONBLOCK) {
 943                         spin_unlock(&info->lock);
 944                         ret = -EAGAIN;
 945                         msg_ptr = NULL;
 946                 } else if (unlikely(timeout < 0)) {
 947                         spin_unlock(&info->lock);
 948                         ret = timeout;
 949                         msg_ptr = NULL;
 950                 } else {
 951                         wait.task = current;
 952                         wait.state = STATE_NONE;
 953                         ret = wq_sleep(info, RECV, timeout, &wait);
 954                         msg_ptr = wait.msg;
 955                 }
 956         } else {
 957                 msg_ptr = msg_get(info);
 958
 959                 inode->i_atime = inode->i_mtime = inode->i_ctime =
 960                                 CURRENT_TIME;
 961
 962                 /* There is now free space in queue. */
 963                 pipelined_receive(info);
 964                 spin_unlock(&info->lock);
 965                 ret = 0;
 966         }
 967         if (ret == 0) {
 968                 ret = msg_ptr->m_ts;
 969
 970                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
 971                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
 972                         ret = -EFAULT;
 973                 }
 974                 free_msg(msg_ptr);
 975         }
 976 out_fput:
 977         fput(filp);
 978 out:
 979         return ret;
 980 }
 981
 982 /*
 983  * Notes: the case when user wants us to deregister (with NULL as pointer)
 984  * and he isn't currently owner of notification, will be silently discarded.
 985  * It isn't explicitly defined in the POSIX.
 986  */
 987 asmlinkage long sys_mq_notify(mqd_t mqdes,
 988                                 const struct sigevent __user *u_notification)
 989 {
 990         int ret;
 991         struct file *filp;
 992         struct sock *sock;
 993         struct inode *inode;
 994         struct sigevent notification;
 995         struct mqueue_inode_info *info;
 996         struct sk_buff *nc;
 997
 998         ret = audit_mq_notify(mqdes, u_notification);
 999         if (ret != 0)
1000                 return ret;
1001
1002         nc = NULL;
1003         sock = NULL;
1004         if (u_notification != NULL) {
1005                 if (copy_from_user(&notification, u_notification,
1006                                         sizeof(struct sigevent)))
1007                         return -EFAULT;
1008
1009                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1010                              notification.sigev_notify != SIGEV_SIGNAL &&
1011                              notification.sigev_notify != SIGEV_THREAD))
1012                         return -EINVAL;
1013                 if (notification.sigev_notify == SIGEV_SIGNAL &&
1014                         !valid_signal(notification.sigev_signo)) {
1015                         return -EINVAL;
1016                 }
1017                 if (notification.sigev_notify == SIGEV_THREAD) {
1018                         /* create the notify skb */
1019                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1020                         ret = -ENOMEM;
1021                         if (!nc)
1022                                 goto out;
1023                         ret = -EFAULT;
1024                         if (copy_from_user(nc->data,
1025                                         notification.sigev_value.sival_ptr,
1026                                         NOTIFY_COOKIE_LEN)) {
1027                                 goto out;
1028                         }
1029
1030                         /* TODO: add a header? */
1031                         skb_put(nc, NOTIFY_COOKIE_LEN);
1032                         /* and attach it to the socket */
1033 retry:
1034                         filp = fget(notification.sigev_signo);
1035                         ret = -EBADF;
1036                         if (!filp)
1037                                 goto out;
1038                         sock = netlink_getsockbyfilp(filp);
1039                         fput(filp);
1040                         if (IS_ERR(sock)) {
1041                                 ret = PTR_ERR(sock);
1042                                 sock = NULL;
1043                                 goto out;
1044                         }
1045
1046                         ret = netlink_attachskb(sock, nc, 0,
1047                                         MAX_SCHEDULE_TIMEOUT, NULL);
1048                         if (ret == 1)
1049                                 goto retry;
1050                         if (ret) {
1051                                 sock = NULL;
1052                                 nc = NULL;
1053                                 goto out;
1054                         }
1055                 }
1056         }
1057
1058         ret = -EBADF;
1059         filp = fget(mqdes);
1060         if (!filp)
1061                 goto out;
1062
1063         inode = filp->f_path.dentry->d_inode;
1064         if (unlikely(filp->f_op != &mqueue_file_operations))
1065                 goto out_fput;
1066         info = MQUEUE_I(inode);
1067
1068         ret = 0;
1069         spin_lock(&info->lock);
1070         if (u_notification == NULL) {
1071                 if (info->notify_owner == task_tgid(current)) {
1072                         remove_notification(info);
1073                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1074                 }
1075         } else if (info->notify_owner != NULL) {
1076                 ret = -EBUSY;
1077         } else {
1078                 switch (notification.sigev_notify) {
1079                 case SIGEV_NONE:
1080                         info->notify.sigev_notify = SIGEV_NONE;
1081                         break;
1082                 case SIGEV_THREAD:
1083                         info->notify_sock = sock;
1084                         info->notify_cookie = nc;
1085                         sock = NULL;
1086                         nc = NULL;
1087                         info->notify.sigev_notify = SIGEV_THREAD;
1088                         break;
1089                 case SIGEV_SIGNAL:
1090                         info->notify.sigev_signo = notification.sigev_signo;
1091                         info->notify.sigev_value = notification.sigev_value;
1092                         info->notify.sigev_notify = SIGEV_SIGNAL;
1093                         break;
1094                 }
1095
1096                 info->notify_owner = get_pid(task_tgid(current));
1097                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1098         }
1099         spin_unlock(&info->lock);
1100 out_fput:
1101         fput(filp);
1102 out:
1103         if (sock) {
1104                 netlink_detachskb(sock, nc);
1105         } else if (nc) {
1106                 dev_kfree_skb(nc);
1107         }
1108         return ret;
1109 }
1110
1111 asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1112                         const struct mq_attr __user *u_mqstat,
1113                         struct mq_attr __user *u_omqstat)
1114 {
1115         int ret;
1116         struct mq_attr mqstat, omqstat;
1117         struct file *filp;
1118         struct inode *inode;
1119         struct mqueue_inode_info *info;
1120
1121         if (u_mqstat != NULL) {
1122                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1123                         return -EFAULT;
1124                 if (mqstat.mq_flags & (~O_NONBLOCK))
1125                         return -EINVAL;
1126         }
1127
1128         ret = -EBADF;
1129         filp = fget(mqdes);
1130         if (!filp)
1131                 goto out;
1132
1133         inode = filp->f_path.dentry->d_inode;
1134         if (unlikely(filp->f_op != &mqueue_file_operations))
1135                 goto out_fput;
1136         info = MQUEUE_I(inode);
1137
1138         spin_lock(&info->lock);
1139
1140         omqstat = info->attr;
1141         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1142         if (u_mqstat) {
1143                 ret = audit_mq_getsetattr(mqdes, &mqstat);
1144                 if (ret != 0)
1145                         goto out;
1146                 if (mqstat.mq_flags & O_NONBLOCK)
1147                         filp->f_flags |= O_NONBLOCK;
1148                 else
1149                         filp->f_flags &= ~O_NONBLOCK;
1150
1151                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1152         }
1153
1154         spin_unlock(&info->lock);
1155
1156         ret = 0;
1157         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1158                                                 sizeof(struct mq_attr)))
1159                 ret = -EFAULT;
1160
1161 out_fput:
1162         fput(filp);
1163 out:
1164         return ret;
1165 }
1166
1167 static const struct inode_operations mqueue_dir_inode_operations = {
1168         .lookup = simple_lookup,
1169         .create = mqueue_create,
1170         .unlink = mqueue_unlink,
1171 };
1172
1173 static const struct file_operations mqueue_file_operations = {
1174         .flush = mqueue_flush_file,
1175         .poll = mqueue_poll_file,
1176         .read = mqueue_read_file,
1177 };
1178
1179 static struct super_operations mqueue_super_ops = {
1180         .alloc_inode = mqueue_alloc_inode,
1181         .destroy_inode = mqueue_destroy_inode,
1182         .statfs = simple_statfs,
1183         .delete_inode = mqueue_delete_inode,
1184         .drop_inode = generic_delete_inode,
1185 };
1186
1187 static struct file_system_type mqueue_fs_type = {
1188         .name = "mqueue",
1189         .get_sb = mqueue_get_sb,
1190         .kill_sb = kill_litter_super,
1191 };
1192
1193 static int msg_max_limit_min = DFLT_MSGMAX;
1194 static int msg_max_limit_max = HARD_MSGMAX;
1195
1196 static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX;
1197 static int msg_maxsize_limit_max = INT_MAX;
1198
1199 static ctl_table mq_sysctls[] = {
1200         {
1201                 .ctl_name       = CTL_QUEUESMAX,
1202                 .procname       = "queues_max",
1203                 .data           = &queues_max,
1204                 .maxlen         = sizeof(int),
1205                 .mode           = 0644,
1206                 .proc_handler   = &proc_dointvec,
1207         },
1208         {
1209                 .ctl_name       = CTL_MSGMAX,
1210                 .procname       = "msg_max",
1211                 .data           = &msg_max,
1212                 .maxlen         = sizeof(int),
1213                 .mode           = 0644,
1214                 .proc_handler   = &proc_dointvec_minmax,
1215                 .extra1         = &msg_max_limit_min,
1216                 .extra2         = &msg_max_limit_max,
1217         },
1218         {
1219                 .ctl_name       = CTL_MSGSIZEMAX,
1220                 .procname       = "msgsize_max",
1221                 .data           = &msgsize_max,
1222                 .maxlen         = sizeof(int),
1223                 .mode           = 0644,
1224                 .proc_handler   = &proc_dointvec_minmax,
1225                 .extra1         = &msg_maxsize_limit_min,
1226                 .extra2         = &msg_maxsize_limit_max,
1227         },
1228         { .ctl_name = 0 }
1229 };
1230
1231 static ctl_table mq_sysctl_dir[] = {
1232         {
1233                 .ctl_name       = FS_MQUEUE,
1234                 .procname       = "mqueue",
1235                 .mode           = 0555,
1236                 .child          = mq_sysctls,
1237         },
1238         { .ctl_name = 0 }
1239 };
1240
1241 static ctl_table mq_sysctl_root[] = {
1242         {
1243                 .ctl_name       = CTL_FS,
1244                 .procname       = "fs",
1245                 .mode           = 0555,
1246                 .child          = mq_sysctl_dir,
1247         },
1248         { .ctl_name = 0 }
1249 };
1250
1251 static int __init init_mqueue_fs(void)
1252 {
1253         int error;
1254
1255         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1256                                 sizeof(struct mqueue_inode_info), 0,
1257                                 SLAB_HWCACHE_ALIGN, init_once, NULL);
1258         if (mqueue_inode_cachep == NULL)
1259                 return -ENOMEM;
1260
1261         /* ignore failues - they are not fatal */
1262         mq_sysctl_table = register_sysctl_table(mq_sysctl_root);
1263
1264         error = register_filesystem(&mqueue_fs_type);
1265         if (error)
1266                 goto out_sysctl;
1267
1268         if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1269                 error = PTR_ERR(mqueue_mnt);
1270                 goto out_filesystem;
1271         }
1272
1273         /* internal initialization - not common for vfs */
1274         queues_count = 0;
1275         spin_lock_init(&mq_lock);
1276
1277         return 0;
1278
1279 out_filesystem:
1280         unregister_filesystem(&mqueue_fs_type);
1281 out_sysctl:
1282         if (mq_sysctl_table)
1283                 unregister_sysctl_table(mq_sysctl_table);
1284         kmem_cache_destroy(mqueue_inode_cachep);
1285         return error;
1286 }
1287
1288 __initcall(init_mqueue_fs);