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