SAFE public projects git trees. - safe/jmp/linux-2.6/blob - ipc/mqueue.c

   1 /*
   2  * POSIX message queues filesystem for Linux.
   3  *
   4  * Copyright (C) 2003,2004  Krzysztof Benedyczak    (golbi@mat.uni.torun.pl)
   5  *                          Michal Wronski          (michal.wronski@gmail.com)
   6  *
   7  * Spinlocks:               Mohamed Abbas           (abbas.mohamed@intel.com)
   8  * Lockless receive & send, fd based notify:
   9  *                          Manfred Spraul          (manfred@colorfullife.com)
  10  *
  11  * Audit:                   George Wilson           (ltcgcw@us.ibm.com)
  12  *
  13  * This file is released under the GPL.
  14  */
  15
  16 #include <linux/capability.h>
  17 #include <linux/init.h>
  18 #include <linux/pagemap.h>
  19 #include <linux/file.h>
  20 #include <linux/mount.h>
  21 #include <linux/namei.h>
  22 #include <linux/sysctl.h>
  23 #include <linux/poll.h>
  24 #include <linux/mqueue.h>
  25 #include <linux/msg.h>
  26 #include <linux/skbuff.h>
  27 #include <linux/netlink.h>
  28 #include <linux/syscalls.h>
  29 #include <linux/audit.h>
  30 #include <linux/signal.h>
  31 #include <linux/mutex.h>
  32 #include <linux/nsproxy.h>
  33 #include <linux/pid.h>
  34
  35 #include <net/sock.h>
  36 #include "util.h"
  37
  38 #define MQUEUE_MAGIC    0x19800202
  39 #define DIRENT_SIZE     20
  40 #define FILENT_SIZE     80
  41
  42 #define SEND            0
  43 #define RECV            1
  44
  45 #define STATE_NONE      0
  46 #define STATE_PENDING   1
  47 #define STATE_READY     2
  48
  49 /* default values */
  50 #define DFLT_QUEUESMAX  256     /* max number of message queues */
  51 #define DFLT_MSGMAX     10      /* max number of messages in each queue */
  52 #define HARD_MSGMAX     (131072/sizeof(void*))
  53 #define DFLT_MSGSIZEMAX 8192    /* max message size */
  54
  55 /*
  56  * Define the ranges various user-specified maximum values can
  57  * be set to.
  58  */
  59 #define MIN_MSGMAX      1               /* min value for msg_max */
  60 #define MAX_MSGMAX      HARD_MSGMAX     /* max value for msg_max */
  61 #define MIN_MSGSIZEMAX  128             /* min value for msgsize_max */
  62 #define MAX_MSGSIZEMAX  (8192*128)      /* max value for msgsize_max */
  63
  64 struct ext_wait_queue {         /* queue of sleeping tasks */
  65         struct task_struct *task;
  66         struct list_head list;
  67         struct msg_msg *msg;    /* ptr of loaded message */
  68         int state;              /* one of STATE_* values */
  69 };
  70
  71 struct mqueue_inode_info {
  72         spinlock_t lock;
  73         struct inode vfs_inode;
  74         wait_queue_head_t wait_q;
  75
  76         struct msg_msg **messages;
  77         struct mq_attr attr;
  78
  79         struct sigevent notify;
  80         struct pid* notify_owner;
  81         struct user_struct *user;       /* user who created, for accounting */
  82         struct sock *notify_sock;
  83         struct sk_buff *notify_cookie;
  84
  85         /* for tasks waiting for free space and messages, respectively */
  86         struct ext_wait_queue e_wait_q[2];
  87
  88         unsigned long qsize; /* size of queue in memory (sum of all msgs) */
  89 };
  90
  91 static const struct inode_operations mqueue_dir_inode_operations;
  92 static const struct file_operations mqueue_file_operations;
  93 static struct super_operations mqueue_super_ops;
  94 static void remove_notification(struct mqueue_inode_info *info);
  95
  96 static spinlock_t mq_lock;
  97 static struct kmem_cache *mqueue_inode_cachep;
  98 static struct vfsmount *mqueue_mnt;
  99
 100 static unsigned int queues_count;
 101 static unsigned int queues_max  = DFLT_QUEUESMAX;
 102 static unsigned int msg_max     = DFLT_MSGMAX;
 103 static unsigned int msgsize_max = DFLT_MSGSIZEMAX;
 104
 105 static struct ctl_table_header * mq_sysctl_table;
 106
 107 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
 108 {
 109         return container_of(inode, struct mqueue_inode_info, vfs_inode);
 110 }
 111
 112 static struct inode *mqueue_get_inode(struct super_block *sb, int mode,
 113                                                         struct mq_attr *attr)
 114 {
 115         struct user_struct *u = current_user();
 116         struct inode *inode;
 117
 118         inode = new_inode(sb);
 119         if (inode) {
 120                 inode->i_mode = mode;
 121                 inode->i_uid = current_fsuid();
 122                 inode->i_gid = current_fsgid();
 123                 inode->i_mtime = inode->i_ctime = inode->i_atime =
 124                                 CURRENT_TIME;
 125
 126                 if (S_ISREG(mode)) {
 127                         struct mqueue_inode_info *info;
 128                         struct task_struct *p = current;
 129                         unsigned long mq_bytes, mq_msg_tblsz;
 130
 131                         inode->i_fop = &mqueue_file_operations;
 132                         inode->i_size = FILENT_SIZE;
 133                         /* mqueue specific info */
 134                         info = MQUEUE_I(inode);
 135                         spin_lock_init(&info->lock);
 136                         init_waitqueue_head(&info->wait_q);
 137                         INIT_LIST_HEAD(&info->e_wait_q[0].list);
 138                         INIT_LIST_HEAD(&info->e_wait_q[1].list);
 139                         info->messages = NULL;
 140                         info->notify_owner = NULL;
 141                         info->qsize = 0;
 142                         info->user = NULL;      /* set when all is ok */
 143                         memset(&info->attr, 0, sizeof(info->attr));
 144                         info->attr.mq_maxmsg = msg_max;
 145                         info->attr.mq_msgsize = msgsize_max;
 146                         if (attr) {
 147                                 info->attr.mq_maxmsg = attr->mq_maxmsg;
 148                                 info->attr.mq_msgsize = attr->mq_msgsize;
 149                         }
 150                         mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
 151                         mq_bytes = (mq_msg_tblsz +
 152                                 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
 153
 154                         spin_lock(&mq_lock);
 155                         if (u->mq_bytes + mq_bytes < u->mq_bytes ||
 156                             u->mq_bytes + mq_bytes >
 157                             p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
 158                                 spin_unlock(&mq_lock);
 159                                 goto out_inode;
 160                         }
 161                         u->mq_bytes += mq_bytes;
 162                         spin_unlock(&mq_lock);
 163
 164                         info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
 165                         if (!info->messages) {
 166                                 spin_lock(&mq_lock);
 167                                 u->mq_bytes -= mq_bytes;
 168                                 spin_unlock(&mq_lock);
 169                                 goto out_inode;
 170                         }
 171                         /* all is ok */
 172                         info->user = get_uid(u);
 173                 } else if (S_ISDIR(mode)) {
 174                         inc_nlink(inode);
 175                         /* Some things misbehave if size == 0 on a directory */
 176                         inode->i_size = 2 * DIRENT_SIZE;
 177                         inode->i_op = &mqueue_dir_inode_operations;
 178                         inode->i_fop = &simple_dir_operations;
 179                 }
 180         }
 181         return inode;
 182 out_inode:
 183         make_bad_inode(inode);
 184         iput(inode);
 185         return NULL;
 186 }
 187
 188 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
 189 {
 190         struct inode *inode;
 191
 192         sb->s_blocksize = PAGE_CACHE_SIZE;
 193         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 194         sb->s_magic = MQUEUE_MAGIC;
 195         sb->s_op = &mqueue_super_ops;
 196
 197         inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
 198         if (!inode)
 199                 return -ENOMEM;
 200
 201         sb->s_root = d_alloc_root(inode);
 202         if (!sb->s_root) {
 203                 iput(inode);
 204                 return -ENOMEM;
 205         }
 206
 207         return 0;
 208 }
 209
 210 static int mqueue_get_sb(struct file_system_type *fs_type,
 211                          int flags, const char *dev_name,
 212                          void *data, struct vfsmount *mnt)
 213 {
 214         return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt);
 215 }
 216
 217 static void init_once(void *foo)
 218 {
 219         struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
 220
 221         inode_init_once(&p->vfs_inode);
 222 }
 223
 224 static struct inode *mqueue_alloc_inode(struct super_block *sb)
 225 {
 226         struct mqueue_inode_info *ei;
 227
 228         ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
 229         if (!ei)
 230                 return NULL;
 231         return &ei->vfs_inode;
 232 }
 233
 234 static void mqueue_destroy_inode(struct inode *inode)
 235 {
 236         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
 237 }
 238
 239 static void mqueue_delete_inode(struct inode *inode)
 240 {
 241         struct mqueue_inode_info *info;
 242         struct user_struct *user;
 243         unsigned long mq_bytes;
 244         int i;
 245
 246         if (S_ISDIR(inode->i_mode)) {
 247                 clear_inode(inode);
 248                 return;
 249         }
 250         info = MQUEUE_I(inode);
 251         spin_lock(&info->lock);
 252         for (i = 0; i < info->attr.mq_curmsgs; i++)
 253                 free_msg(info->messages[i]);
 254         kfree(info->messages);
 255         spin_unlock(&info->lock);
 256
 257         clear_inode(inode);
 258
 259         mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
 260                    (info->attr.mq_maxmsg * info->attr.mq_msgsize));
 261         user = info->user;
 262         if (user) {
 263                 spin_lock(&mq_lock);
 264                 user->mq_bytes -= mq_bytes;
 265                 queues_count--;
 266                 spin_unlock(&mq_lock);
 267                 free_uid(user);
 268         }
 269 }
 270
 271 static int mqueue_create(struct inode *dir, struct dentry *dentry,
 272                                 int mode, struct nameidata *nd)
 273 {
 274         struct inode *inode;
 275         struct mq_attr *attr = dentry->d_fsdata;
 276         int error;
 277
 278         spin_lock(&mq_lock);
 279         if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
 280                 error = -ENOSPC;
 281                 goto out_lock;
 282         }
 283         queues_count++;
 284         spin_unlock(&mq_lock);
 285
 286         inode = mqueue_get_inode(dir->i_sb, mode, attr);
 287         if (!inode) {
 288                 error = -ENOMEM;
 289                 spin_lock(&mq_lock);
 290                 queues_count--;
 291                 goto out_lock;
 292         }
 293
 294         dir->i_size += DIRENT_SIZE;
 295         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 296
 297         d_instantiate(dentry, inode);
 298         dget(dentry);
 299         return 0;
 300 out_lock:
 301         spin_unlock(&mq_lock);
 302         return error;
 303 }
 304
 305 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
 306 {
 307         struct inode *inode = dentry->d_inode;
 308
 309         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 310         dir->i_size -= DIRENT_SIZE;
 311         drop_nlink(inode);
 312         dput(dentry);
 313         return 0;
 314 }
 315
 316 /*
 317 *       This is routine for system read from queue file.
 318 *       To avoid mess with doing here some sort of mq_receive we allow
 319 *       to read only queue size & notification info (the only values
 320 *       that are interesting from user point of view and aren't accessible
 321 *       through std routines)
 322 */
 323 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
 324                                 size_t count, loff_t *off)
 325 {
 326         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 327         char buffer[FILENT_SIZE];
 328         ssize_t ret;
 329
 330         spin_lock(&info->lock);
 331         snprintf(buffer, sizeof(buffer),
 332                         "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
 333                         info->qsize,
 334                         info->notify_owner ? info->notify.sigev_notify : 0,
 335                         (info->notify_owner &&
 336                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
 337                                 info->notify.sigev_signo : 0,
 338                         pid_vnr(info->notify_owner));
 339         spin_unlock(&info->lock);
 340         buffer[sizeof(buffer)-1] = '\0';
 341
 342         ret = simple_read_from_buffer(u_data, count, off, buffer,
 343                                 strlen(buffer));
 344         if (ret <= 0)
 345                 return ret;
 346
 347         filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
 348         return ret;
 349 }
 350
 351 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
 352 {
 353         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 354
 355         spin_lock(&info->lock);
 356         if (task_tgid(current) == info->notify_owner)
 357                 remove_notification(info);
 358
 359         spin_unlock(&info->lock);
 360         return 0;
 361 }
 362
 363 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
 364 {
 365         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 366         int retval = 0;
 367
 368         poll_wait(filp, &info->wait_q, poll_tab);
 369
 370         spin_lock(&info->lock);
 371         if (info->attr.mq_curmsgs)
 372                 retval = POLLIN | POLLRDNORM;
 373
 374         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
 375                 retval |= POLLOUT | POLLWRNORM;
 376         spin_unlock(&info->lock);
 377
 378         return retval;
 379 }
 380
 381 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
 382 static void wq_add(struct mqueue_inode_info *info, int sr,
 383                         struct ext_wait_queue *ewp)
 384 {
 385         struct ext_wait_queue *walk;
 386
 387         ewp->task = current;
 388
 389         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
 390                 if (walk->task->static_prio <= current->static_prio) {
 391                         list_add_tail(&ewp->list, &walk->list);
 392                         return;
 393                 }
 394         }
 395         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
 396 }
 397
 398 /*
 399  * Puts current task to sleep. Caller must hold queue lock. After return
 400  * lock isn't held.
 401  * sr: SEND or RECV
 402  */
 403 static int wq_sleep(struct mqueue_inode_info *info, int sr,
 404                         long timeout, struct ext_wait_queue *ewp)
 405 {
 406         int retval;
 407         signed long time;
 408
 409         wq_add(info, sr, ewp);
 410
 411         for (;;) {
 412                 set_current_state(TASK_INTERRUPTIBLE);
 413
 414                 spin_unlock(&info->lock);
 415                 time = schedule_timeout(timeout);
 416
 417                 while (ewp->state == STATE_PENDING)
 418                         cpu_relax();
 419
 420                 if (ewp->state == STATE_READY) {
 421                         retval = 0;
 422                         goto out;
 423                 }
 424                 spin_lock(&info->lock);
 425                 if (ewp->state == STATE_READY) {
 426                         retval = 0;
 427                         goto out_unlock;
 428                 }
 429                 if (signal_pending(current)) {
 430                         retval = -ERESTARTSYS;
 431                         break;
 432                 }
 433                 if (time == 0) {
 434                         retval = -ETIMEDOUT;
 435                         break;
 436                 }
 437         }
 438         list_del(&ewp->list);
 439 out_unlock:
 440         spin_unlock(&info->lock);
 441 out:
 442         return retval;
 443 }
 444
 445 /*
 446  * Returns waiting task that should be serviced first or NULL if none exists
 447  */
 448 static struct ext_wait_queue *wq_get_first_waiter(
 449                 struct mqueue_inode_info *info, int sr)
 450 {
 451         struct list_head *ptr;
 452
 453         ptr = info->e_wait_q[sr].list.prev;
 454         if (ptr == &info->e_wait_q[sr].list)
 455                 return NULL;
 456         return list_entry(ptr, struct ext_wait_queue, list);
 457 }
 458
 459 /* Auxiliary functions to manipulate messages' list */
 460 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
 461 {
 462         int k;
 463
 464         k = info->attr.mq_curmsgs - 1;
 465         while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
 466                 info->messages[k + 1] = info->messages[k];
 467                 k--;
 468         }
 469         info->attr.mq_curmsgs++;
 470         info->qsize += ptr->m_ts;
 471         info->messages[k + 1] = ptr;
 472 }
 473
 474 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
 475 {
 476         info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
 477         return info->messages[info->attr.mq_curmsgs];
 478 }
 479
 480 static inline void set_cookie(struct sk_buff *skb, char code)
 481 {
 482         ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
 483 }
 484
 485 /*
 486  * The next function is only to split too long sys_mq_timedsend
 487  */
 488 static void __do_notify(struct mqueue_inode_info *info)
 489 {
 490         /* notification
 491          * invoked when there is registered process and there isn't process
 492          * waiting synchronously for message AND state of queue changed from
 493          * empty to not empty. Here we are sure that no one is waiting
 494          * synchronously. */
 495         if (info->notify_owner &&
 496             info->attr.mq_curmsgs == 1) {
 497                 struct siginfo sig_i;
 498                 switch (info->notify.sigev_notify) {
 499                 case SIGEV_NONE:
 500                         break;
 501                 case SIGEV_SIGNAL:
 502                         /* sends signal */
 503
 504                         sig_i.si_signo = info->notify.sigev_signo;
 505                         sig_i.si_errno = 0;
 506                         sig_i.si_code = SI_MESGQ;
 507                         sig_i.si_value = info->notify.sigev_value;
 508                         sig_i.si_pid = task_tgid_vnr(current);
 509                         sig_i.si_uid = current_uid();
 510
 511                         kill_pid_info(info->notify.sigev_signo,
 512                                       &sig_i, info->notify_owner);
 513                         break;
 514                 case SIGEV_THREAD:
 515                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
 516                         netlink_sendskb(info->notify_sock, info->notify_cookie);
 517                         break;
 518                 }
 519                 /* after notification unregisters process */
 520                 put_pid(info->notify_owner);
 521                 info->notify_owner = NULL;
 522         }
 523         wake_up(&info->wait_q);
 524 }
 525
 526 static long prepare_timeout(const struct timespec __user *u_arg)
 527 {
 528         struct timespec ts, nowts;
 529         long timeout;
 530
 531         if (u_arg) {
 532                 if (unlikely(copy_from_user(&ts, u_arg,
 533                                         sizeof(struct timespec))))
 534                         return -EFAULT;
 535
 536                 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0
 537                         || ts.tv_nsec >= NSEC_PER_SEC))
 538                         return -EINVAL;
 539                 nowts = CURRENT_TIME;
 540                 /* first subtract as jiffies can't be too big */
 541                 ts.tv_sec -= nowts.tv_sec;
 542                 if (ts.tv_nsec < nowts.tv_nsec) {
 543                         ts.tv_nsec += NSEC_PER_SEC;
 544                         ts.tv_sec--;
 545                 }
 546                 ts.tv_nsec -= nowts.tv_nsec;
 547                 if (ts.tv_sec < 0)
 548                         return 0;
 549
 550                 timeout = timespec_to_jiffies(&ts) + 1;
 551         } else
 552                 return MAX_SCHEDULE_TIMEOUT;
 553
 554         return timeout;
 555 }
 556
 557 static void remove_notification(struct mqueue_inode_info *info)
 558 {
 559         if (info->notify_owner != NULL &&
 560             info->notify.sigev_notify == SIGEV_THREAD) {
 561                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
 562                 netlink_sendskb(info->notify_sock, info->notify_cookie);
 563         }
 564         put_pid(info->notify_owner);
 565         info->notify_owner = NULL;
 566 }
 567
 568 static int mq_attr_ok(struct mq_attr *attr)
 569 {
 570         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
 571                 return 0;
 572         if (capable(CAP_SYS_RESOURCE)) {
 573                 if (attr->mq_maxmsg > HARD_MSGMAX)
 574                         return 0;
 575         } else {
 576                 if (attr->mq_maxmsg > msg_max ||
 577                                 attr->mq_msgsize > msgsize_max)
 578                         return 0;
 579         }
 580         /* check for overflow */
 581         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
 582                 return 0;
 583         if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
 584             (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
 585             (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
 586                 return 0;
 587         return 1;
 588 }
 589
 590 /*
 591  * Invoked when creating a new queue via sys_mq_open
 592  */
 593 static struct file *do_create(struct dentry *dir, struct dentry *dentry,
 594                         int oflag, mode_t mode, struct mq_attr __user *u_attr)
 595 {
 596         const struct cred *cred = current_cred();
 597         struct mq_attr attr;
 598         struct file *result;
 599         int ret;
 600
 601         if (u_attr) {
 602                 ret = -EFAULT;
 603                 if (copy_from_user(&attr, u_attr, sizeof(attr)))
 604                         goto out;
 605                 ret = -EINVAL;
 606                 if (!mq_attr_ok(&attr))
 607                         goto out;
 608                 /* store for use during create */
 609                 dentry->d_fsdata = &attr;
 610         }
 611
 612         mode &= ~current->fs->umask;
 613         ret = mnt_want_write(mqueue_mnt);
 614         if (ret)
 615                 goto out;
 616         ret = vfs_create(dir->d_inode, dentry, mode, NULL);
 617         dentry->d_fsdata = NULL;
 618         if (ret)
 619                 goto out_drop_write;
 620
 621         result = dentry_open(dentry, mqueue_mnt, oflag, cred);
 622         /*
 623          * dentry_open() took a persistent mnt_want_write(),
 624          * so we can now drop this one.
 625          */
 626         mnt_drop_write(mqueue_mnt);
 627         return result;
 628
 629 out_drop_write:
 630         mnt_drop_write(mqueue_mnt);
 631 out:
 632         dput(dentry);
 633         mntput(mqueue_mnt);
 634         return ERR_PTR(ret);
 635 }
 636
 637 /* Opens existing queue */
 638 static struct file *do_open(struct dentry *dentry, int oflag)
 639 {
 640         const struct cred *cred = current_cred();
 641
 642         static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
 643                                                   MAY_READ | MAY_WRITE };
 644
 645         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
 646                 dput(dentry);
 647                 mntput(mqueue_mnt);
 648                 return ERR_PTR(-EINVAL);
 649         }
 650
 651         if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
 652                 dput(dentry);
 653                 mntput(mqueue_mnt);
 654                 return ERR_PTR(-EACCES);
 655         }
 656
 657         return dentry_open(dentry, mqueue_mnt, oflag, cred);
 658 }
 659
 660 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
 661                                 struct mq_attr __user *u_attr)
 662 {
 663         struct dentry *dentry;
 664         struct file *filp;
 665         char *name;
 666         int fd, error;
 667
 668         error = audit_mq_open(oflag, mode, u_attr);
 669         if (error != 0)
 670                 return error;
 671
 672         if (IS_ERR(name = getname(u_name)))
 673                 return PTR_ERR(name);
 674
 675         fd = get_unused_fd_flags(O_CLOEXEC);
 676         if (fd < 0)
 677                 goto out_putname;
 678
 679         mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
 680         dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
 681         if (IS_ERR(dentry)) {
 682                 error = PTR_ERR(dentry);
 683                 goto out_err;
 684         }
 685         mntget(mqueue_mnt);
 686
 687         if (oflag & O_CREAT) {
 688                 if (dentry->d_inode) {  /* entry already exists */
 689                         audit_inode(name, dentry);
 690                         error = -EEXIST;
 691                         if (oflag & O_EXCL)
 692                                 goto out;
 693                         filp = do_open(dentry, oflag);
 694                 } else {
 695                         filp = do_create(mqueue_mnt->mnt_root, dentry,
 696                                                 oflag, mode, u_attr);
 697                 }
 698         } else {
 699                 error = -ENOENT;
 700                 if (!dentry->d_inode)
 701                         goto out;
 702                 audit_inode(name, dentry);
 703                 filp = do_open(dentry, oflag);
 704         }
 705
 706         if (IS_ERR(filp)) {
 707                 error = PTR_ERR(filp);
 708                 goto out_putfd;
 709         }
 710
 711         fd_install(fd, filp);
 712         goto out_upsem;
 713
 714 out:
 715         dput(dentry);
 716         mntput(mqueue_mnt);
 717 out_putfd:
 718         put_unused_fd(fd);
 719 out_err:
 720         fd = error;
 721 out_upsem:
 722         mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
 723 out_putname:
 724         putname(name);
 725         return fd;
 726 }
 727
 728 asmlinkage long sys_mq_unlink(const char __user *u_name)
 729 {
 730         int err;
 731         char *name;
 732         struct dentry *dentry;
 733         struct inode *inode = NULL;
 734
 735         name = getname(u_name);
 736         if (IS_ERR(name))
 737                 return PTR_ERR(name);
 738
 739         mutex_lock_nested(&mqueue_mnt->mnt_root->d_inode->i_mutex,
 740                         I_MUTEX_PARENT);
 741         dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
 742         if (IS_ERR(dentry)) {
 743                 err = PTR_ERR(dentry);
 744                 goto out_unlock;
 745         }
 746
 747         if (!dentry->d_inode) {
 748                 err = -ENOENT;
 749                 goto out_err;
 750         }
 751
 752         inode = dentry->d_inode;
 753         if (inode)
 754                 atomic_inc(&inode->i_count);
 755         err = mnt_want_write(mqueue_mnt);
 756         if (err)
 757                 goto out_err;
 758         err = vfs_unlink(dentry->d_parent->d_inode, dentry);
 759         mnt_drop_write(mqueue_mnt);
 760 out_err:
 761         dput(dentry);
 762
 763 out_unlock:
 764         mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
 765         putname(name);
 766         if (inode)
 767                 iput(inode);
 768
 769         return err;
 770 }
 771
 772 /* Pipelined send and receive functions.
 773  *
 774  * If a receiver finds no waiting message, then it registers itself in the
 775  * list of waiting receivers. A sender checks that list before adding the new
 776  * message into the message array. If there is a waiting receiver, then it
 777  * bypasses the message array and directly hands the message over to the
 778  * receiver.
 779  * The receiver accepts the message and returns without grabbing the queue
 780  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
 781  * are necessary. The same algorithm is used for sysv semaphores, see
 782  * ipc/sem.c for more details.
 783  *
 784  * The same algorithm is used for senders.
 785  */
 786
 787 /* pipelined_send() - send a message directly to the task waiting in
 788  * sys_mq_timedreceive() (without inserting message into a queue).
 789  */
 790 static inline void pipelined_send(struct mqueue_inode_info *info,
 791                                   struct msg_msg *message,
 792                                   struct ext_wait_queue *receiver)
 793 {
 794         receiver->msg = message;
 795         list_del(&receiver->list);
 796         receiver->state = STATE_PENDING;
 797         wake_up_process(receiver->task);
 798         smp_wmb();
 799         receiver->state = STATE_READY;
 800 }
 801
 802 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
 803  * gets its message and put to the queue (we have one free place for sure). */
 804 static inline void pipelined_receive(struct mqueue_inode_info *info)
 805 {
 806         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
 807
 808         if (!sender) {
 809                 /* for poll */
 810                 wake_up_interruptible(&info->wait_q);
 811                 return;
 812         }
 813         msg_insert(sender->msg, info);
 814         list_del(&sender->list);
 815         sender->state = STATE_PENDING;
 816         wake_up_process(sender->task);
 817         smp_wmb();
 818         sender->state = STATE_READY;
 819 }
 820
 821 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
 822         size_t msg_len, unsigned int msg_prio,
 823         const struct timespec __user *u_abs_timeout)
 824 {
 825         struct file *filp;
 826         struct inode *inode;
 827         struct ext_wait_queue wait;
 828         struct ext_wait_queue *receiver;
 829         struct msg_msg *msg_ptr;
 830         struct mqueue_inode_info *info;
 831         long timeout;
 832         int ret;
 833
 834         ret = audit_mq_timedsend(mqdes, msg_len, msg_prio, u_abs_timeout);
 835         if (ret != 0)
 836                 return ret;
 837
 838         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
 839                 return -EINVAL;
 840
 841         timeout = prepare_timeout(u_abs_timeout);
 842
 843         ret = -EBADF;
 844         filp = fget(mqdes);
 845         if (unlikely(!filp))
 846                 goto out;
 847
 848         inode = filp->f_path.dentry->d_inode;
 849         if (unlikely(filp->f_op != &mqueue_file_operations))
 850                 goto out_fput;
 851         info = MQUEUE_I(inode);
 852         audit_inode(NULL, filp->f_path.dentry);
 853
 854         if (unlikely(!(filp->f_mode & FMODE_WRITE)))
 855                 goto out_fput;
 856
 857         if (unlikely(msg_len > info->attr.mq_msgsize)) {
 858                 ret = -EMSGSIZE;
 859                 goto out_fput;
 860         }
 861
 862         /* First try to allocate memory, before doing anything with
 863          * existing queues. */
 864         msg_ptr = load_msg(u_msg_ptr, msg_len);
 865         if (IS_ERR(msg_ptr)) {
 866                 ret = PTR_ERR(msg_ptr);
 867                 goto out_fput;
 868         }
 869         msg_ptr->m_ts = msg_len;
 870         msg_ptr->m_type = msg_prio;
 871
 872         spin_lock(&info->lock);
 873
 874         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
 875                 if (filp->f_flags & O_NONBLOCK) {
 876                         spin_unlock(&info->lock);
 877                         ret = -EAGAIN;
 878                 } else if (unlikely(timeout < 0)) {
 879                         spin_unlock(&info->lock);
 880                         ret = timeout;
 881                 } else {
 882                         wait.task = current;
 883                         wait.msg = (void *) msg_ptr;
 884                         wait.state = STATE_NONE;
 885                         ret = wq_sleep(info, SEND, timeout, &wait);
 886                 }
 887                 if (ret < 0)
 888                         free_msg(msg_ptr);
 889         } else {
 890                 receiver = wq_get_first_waiter(info, RECV);
 891                 if (receiver) {
 892                         pipelined_send(info, msg_ptr, receiver);
 893                 } else {
 894                         /* adds message to the queue */
 895                         msg_insert(msg_ptr, info);
 896                         __do_notify(info);
 897                 }
 898                 inode->i_atime = inode->i_mtime = inode->i_ctime =
 899                                 CURRENT_TIME;
 900                 spin_unlock(&info->lock);
 901                 ret = 0;
 902         }
 903 out_fput:
 904         fput(filp);
 905 out:
 906         return ret;
 907 }
 908
 909 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
 910         size_t msg_len, unsigned int __user *u_msg_prio,
 911         const struct timespec __user *u_abs_timeout)
 912 {
 913         long timeout;
 914         ssize_t ret;
 915         struct msg_msg *msg_ptr;
 916         struct file *filp;
 917         struct inode *inode;
 918         struct mqueue_inode_info *info;
 919         struct ext_wait_queue wait;
 920
 921         ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout);
 922         if (ret != 0)
 923                 return ret;
 924
 925         timeout = prepare_timeout(u_abs_timeout);
 926
 927         ret = -EBADF;
 928         filp = fget(mqdes);
 929         if (unlikely(!filp))
 930                 goto out;
 931
 932         inode = filp->f_path.dentry->d_inode;
 933         if (unlikely(filp->f_op != &mqueue_file_operations))
 934                 goto out_fput;
 935         info = MQUEUE_I(inode);
 936         audit_inode(NULL, filp->f_path.dentry);
 937
 938         if (unlikely(!(filp->f_mode & FMODE_READ)))
 939                 goto out_fput;
 940
 941         /* checks if buffer is big enough */
 942         if (unlikely(msg_len < info->attr.mq_msgsize)) {
 943                 ret = -EMSGSIZE;
 944                 goto out_fput;
 945         }
 946
 947         spin_lock(&info->lock);
 948         if (info->attr.mq_curmsgs == 0) {
 949                 if (filp->f_flags & O_NONBLOCK) {
 950                         spin_unlock(&info->lock);
 951                         ret = -EAGAIN;
 952                         msg_ptr = NULL;
 953                 } else if (unlikely(timeout < 0)) {
 954                         spin_unlock(&info->lock);
 955                         ret = timeout;
 956                         msg_ptr = NULL;
 957                 } else {
 958                         wait.task = current;
 959                         wait.state = STATE_NONE;
 960                         ret = wq_sleep(info, RECV, timeout, &wait);
 961                         msg_ptr = wait.msg;
 962                 }
 963         } else {
 964                 msg_ptr = msg_get(info);
 965
 966                 inode->i_atime = inode->i_mtime = inode->i_ctime =
 967                                 CURRENT_TIME;
 968
 969                 /* There is now free space in queue. */
 970                 pipelined_receive(info);
 971                 spin_unlock(&info->lock);
 972                 ret = 0;
 973         }
 974         if (ret == 0) {
 975                 ret = msg_ptr->m_ts;
 976
 977                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
 978                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
 979                         ret = -EFAULT;
 980                 }
 981                 free_msg(msg_ptr);
 982         }
 983 out_fput:
 984         fput(filp);
 985 out:
 986         return ret;
 987 }
 988
 989 /*
 990  * Notes: the case when user wants us to deregister (with NULL as pointer)
 991  * and he isn't currently owner of notification, will be silently discarded.
 992  * It isn't explicitly defined in the POSIX.
 993  */
 994 asmlinkage long sys_mq_notify(mqd_t mqdes,
 995                                 const struct sigevent __user *u_notification)
 996 {
 997         int ret;
 998         struct file *filp;
 999         struct sock *sock;
1000         struct inode *inode;
1001         struct sigevent notification;
1002         struct mqueue_inode_info *info;
1003         struct sk_buff *nc;
1004
1005         ret = audit_mq_notify(mqdes, u_notification);
1006         if (ret != 0)
1007                 return ret;
1008
1009         nc = NULL;
1010         sock = NULL;
1011         if (u_notification != NULL) {
1012                 if (copy_from_user(&notification, u_notification,
1013                                         sizeof(struct sigevent)))
1014                         return -EFAULT;
1015
1016                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1017                              notification.sigev_notify != SIGEV_SIGNAL &&
1018                              notification.sigev_notify != SIGEV_THREAD))
1019                         return -EINVAL;
1020                 if (notification.sigev_notify == SIGEV_SIGNAL &&
1021                         !valid_signal(notification.sigev_signo)) {
1022                         return -EINVAL;
1023                 }
1024                 if (notification.sigev_notify == SIGEV_THREAD) {
1025                         long timeo;
1026
1027                         /* create the notify skb */
1028                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1029                         ret = -ENOMEM;
1030                         if (!nc)
1031                                 goto out;
1032                         ret = -EFAULT;
1033                         if (copy_from_user(nc->data,
1034                                         notification.sigev_value.sival_ptr,
1035                                         NOTIFY_COOKIE_LEN)) {
1036                                 goto out;
1037                         }
1038
1039                         /* TODO: add a header? */
1040                         skb_put(nc, NOTIFY_COOKIE_LEN);
1041                         /* and attach it to the socket */
1042 retry:
1043                         filp = fget(notification.sigev_signo);
1044                         ret = -EBADF;
1045                         if (!filp)
1046                                 goto out;
1047                         sock = netlink_getsockbyfilp(filp);
1048                         fput(filp);
1049                         if (IS_ERR(sock)) {
1050                                 ret = PTR_ERR(sock);
1051                                 sock = NULL;
1052                                 goto out;
1053                         }
1054
1055                         timeo = MAX_SCHEDULE_TIMEOUT;
1056                         ret = netlink_attachskb(sock, nc, &timeo, NULL);
1057                         if (ret == 1)
1058                                 goto retry;
1059                         if (ret) {
1060                                 sock = NULL;
1061                                 nc = NULL;
1062                                 goto out;
1063                         }
1064                 }
1065         }
1066
1067         ret = -EBADF;
1068         filp = fget(mqdes);
1069         if (!filp)
1070                 goto out;
1071
1072         inode = filp->f_path.dentry->d_inode;
1073         if (unlikely(filp->f_op != &mqueue_file_operations))
1074                 goto out_fput;
1075         info = MQUEUE_I(inode);
1076
1077         ret = 0;
1078         spin_lock(&info->lock);
1079         if (u_notification == NULL) {
1080                 if (info->notify_owner == task_tgid(current)) {
1081                         remove_notification(info);
1082                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1083                 }
1084         } else if (info->notify_owner != NULL) {
1085                 ret = -EBUSY;
1086         } else {
1087                 switch (notification.sigev_notify) {
1088                 case SIGEV_NONE:
1089                         info->notify.sigev_notify = SIGEV_NONE;
1090                         break;
1091                 case SIGEV_THREAD:
1092                         info->notify_sock = sock;
1093                         info->notify_cookie = nc;
1094                         sock = NULL;
1095                         nc = NULL;
1096                         info->notify.sigev_notify = SIGEV_THREAD;
1097                         break;
1098                 case SIGEV_SIGNAL:
1099                         info->notify.sigev_signo = notification.sigev_signo;
1100                         info->notify.sigev_value = notification.sigev_value;
1101                         info->notify.sigev_notify = SIGEV_SIGNAL;
1102                         break;
1103                 }
1104
1105                 info->notify_owner = get_pid(task_tgid(current));
1106                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1107         }
1108         spin_unlock(&info->lock);
1109 out_fput:
1110         fput(filp);
1111 out:
1112         if (sock) {
1113                 netlink_detachskb(sock, nc);
1114         } else if (nc) {
1115                 dev_kfree_skb(nc);
1116         }
1117         return ret;
1118 }
1119
1120 asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1121                         const struct mq_attr __user *u_mqstat,
1122                         struct mq_attr __user *u_omqstat)
1123 {
1124         int ret;
1125         struct mq_attr mqstat, omqstat;
1126         struct file *filp;
1127         struct inode *inode;
1128         struct mqueue_inode_info *info;
1129
1130         if (u_mqstat != NULL) {
1131                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1132                         return -EFAULT;
1133                 if (mqstat.mq_flags & (~O_NONBLOCK))
1134                         return -EINVAL;
1135         }
1136
1137         ret = -EBADF;
1138         filp = fget(mqdes);
1139         if (!filp)
1140                 goto out;
1141
1142         inode = filp->f_path.dentry->d_inode;
1143         if (unlikely(filp->f_op != &mqueue_file_operations))
1144                 goto out_fput;
1145         info = MQUEUE_I(inode);
1146
1147         spin_lock(&info->lock);
1148
1149         omqstat = info->attr;
1150         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1151         if (u_mqstat) {
1152                 ret = audit_mq_getsetattr(mqdes, &mqstat);
1153                 if (ret != 0) {
1154                         spin_unlock(&info->lock);
1155                         goto out_fput;
1156                 }
1157                 if (mqstat.mq_flags & O_NONBLOCK)
1158                         filp->f_flags |= O_NONBLOCK;
1159                 else
1160                         filp->f_flags &= ~O_NONBLOCK;
1161
1162                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1163         }
1164
1165         spin_unlock(&info->lock);
1166
1167         ret = 0;
1168         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1169                                                 sizeof(struct mq_attr)))
1170                 ret = -EFAULT;
1171
1172 out_fput:
1173         fput(filp);
1174 out:
1175         return ret;
1176 }
1177
1178 static const struct inode_operations mqueue_dir_inode_operations = {
1179         .lookup = simple_lookup,
1180         .create = mqueue_create,
1181         .unlink = mqueue_unlink,
1182 };
1183
1184 static const struct file_operations mqueue_file_operations = {
1185         .flush = mqueue_flush_file,
1186         .poll = mqueue_poll_file,
1187         .read = mqueue_read_file,
1188 };
1189
1190 static struct super_operations mqueue_super_ops = {
1191         .alloc_inode = mqueue_alloc_inode,
1192         .destroy_inode = mqueue_destroy_inode,
1193         .statfs = simple_statfs,
1194         .delete_inode = mqueue_delete_inode,
1195         .drop_inode = generic_delete_inode,
1196 };
1197
1198 static struct file_system_type mqueue_fs_type = {
1199         .name = "mqueue",
1200         .get_sb = mqueue_get_sb,
1201         .kill_sb = kill_litter_super,
1202 };
1203
1204 static int msg_max_limit_min = MIN_MSGMAX;
1205 static int msg_max_limit_max = MAX_MSGMAX;
1206
1207 static int msg_maxsize_limit_min = MIN_MSGSIZEMAX;
1208 static int msg_maxsize_limit_max = MAX_MSGSIZEMAX;
1209
1210 static ctl_table mq_sysctls[] = {
1211         {
1212                 .procname       = "queues_max",
1213                 .data           = &queues_max,
1214                 .maxlen         = sizeof(int),
1215                 .mode           = 0644,
1216                 .proc_handler   = &proc_dointvec,
1217         },
1218         {
1219                 .procname       = "msg_max",
1220                 .data           = &msg_max,
1221                 .maxlen         = sizeof(int),
1222                 .mode           = 0644,
1223                 .proc_handler   = &proc_dointvec_minmax,
1224                 .extra1         = &msg_max_limit_min,
1225                 .extra2         = &msg_max_limit_max,
1226         },
1227         {
1228                 .procname       = "msgsize_max",
1229                 .data           = &msgsize_max,
1230                 .maxlen         = sizeof(int),
1231                 .mode           = 0644,
1232                 .proc_handler   = &proc_dointvec_minmax,
1233                 .extra1         = &msg_maxsize_limit_min,
1234                 .extra2         = &msg_maxsize_limit_max,
1235         },
1236         { .ctl_name = 0 }
1237 };
1238
1239 static ctl_table mq_sysctl_dir[] = {
1240         {
1241                 .procname       = "mqueue",
1242                 .mode           = 0555,
1243                 .child          = mq_sysctls,
1244         },
1245         { .ctl_name = 0 }
1246 };
1247
1248 static ctl_table mq_sysctl_root[] = {
1249         {
1250                 .ctl_name       = CTL_FS,
1251                 .procname       = "fs",
1252                 .mode           = 0555,
1253                 .child          = mq_sysctl_dir,
1254         },
1255         { .ctl_name = 0 }
1256 };
1257
1258 static int __init init_mqueue_fs(void)
1259 {
1260         int error;
1261
1262         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1263                                 sizeof(struct mqueue_inode_info), 0,
1264                                 SLAB_HWCACHE_ALIGN, init_once);
1265         if (mqueue_inode_cachep == NULL)
1266                 return -ENOMEM;
1267
1268         /* ignore failues - they are not fatal */
1269         mq_sysctl_table = register_sysctl_table(mq_sysctl_root);
1270
1271         error = register_filesystem(&mqueue_fs_type);
1272         if (error)
1273                 goto out_sysctl;
1274
1275         if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1276                 error = PTR_ERR(mqueue_mnt);
1277                 goto out_filesystem;
1278         }
1279
1280         /* internal initialization - not common for vfs */
1281         queues_count = 0;
1282         spin_lock_init(&mq_lock);
1283
1284         return 0;
1285
1286 out_filesystem:
1287         unregister_filesystem(&mqueue_fs_type);
1288 out_sysctl:
1289         if (mq_sysctl_table)
1290                 unregister_sysctl_table(mq_sysctl_table);
1291         kmem_cache_destroy(mqueue_inode_cachep);
1292         return error;
1293 }
1294
1295 __initcall(init_mqueue_fs);