ipc/mqueue.c

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