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 #include <linux/ipc_namespace.h>
  35 #include <linux/slab.h>
  36
  37 #include <net/sock.h>
  38 #include "util.h"
  39
  40 #define MQUEUE_MAGIC    0x19800202
  41 #define DIRENT_SIZE     20
  42 #define FILENT_SIZE     80
  43
  44 #define SEND            0
  45 #define RECV            1
  46
  47 #define STATE_NONE      0
  48 #define STATE_PENDING   1
  49 #define STATE_READY     2
  50
  51 struct ext_wait_queue {         /* queue of sleeping tasks */
  52         struct task_struct *task;
  53         struct list_head list;
  54         struct msg_msg *msg;    /* ptr of loaded message */
  55         int state;              /* one of STATE_* values */
  56 };
  57
  58 struct mqueue_inode_info {
  59         spinlock_t lock;
  60         struct inode vfs_inode;
  61         wait_queue_head_t wait_q;
  62
  63         struct msg_msg **messages;
  64         struct mq_attr attr;
  65
  66         struct sigevent notify;
  67         struct pid* notify_owner;
  68         struct user_struct *user;       /* user who created, for accounting */
  69         struct sock *notify_sock;
  70         struct sk_buff *notify_cookie;
  71
  72         /* for tasks waiting for free space and messages, respectively */
  73         struct ext_wait_queue e_wait_q[2];
  74
  75         unsigned long qsize; /* size of queue in memory (sum of all msgs) */
  76 };
  77
  78 static const struct inode_operations mqueue_dir_inode_operations;
  79 static const struct file_operations mqueue_file_operations;
  80 static const struct super_operations mqueue_super_ops;
  81 static void remove_notification(struct mqueue_inode_info *info);
  82
  83 static struct kmem_cache *mqueue_inode_cachep;
  84
  85 static struct ctl_table_header * mq_sysctl_table;
  86
  87 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
  88 {
  89         return container_of(inode, struct mqueue_inode_info, vfs_inode);
  90 }
  91
  92 /*
  93  * This routine should be called with the mq_lock held.
  94  */
  95 static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
  96 {
  97         return get_ipc_ns(inode->i_sb->s_fs_info);
  98 }
  99
 100 static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
 101 {
 102         struct ipc_namespace *ns;
 103
 104         spin_lock(&mq_lock);
 105         ns = __get_ns_from_inode(inode);
 106         spin_unlock(&mq_lock);
 107         return ns;
 108 }
 109
 110 static struct inode *mqueue_get_inode(struct super_block *sb,
 111                 struct ipc_namespace *ipc_ns, int mode,
 112                 struct mq_attr *attr)
 113 {
 114         struct user_struct *u = current_user();
 115         struct inode *inode;
 116
 117         inode = new_inode(sb);
 118         if (inode) {
 119                 inode->i_mode = mode;
 120                 inode->i_uid = current_fsuid();
 121                 inode->i_gid = current_fsgid();
 122                 inode->i_mtime = inode->i_ctime = inode->i_atime =
 123                                 CURRENT_TIME;
 124
 125                 if (S_ISREG(mode)) {
 126                         struct mqueue_inode_info *info;
 127                         struct task_struct *p = current;
 128                         unsigned long mq_bytes, mq_msg_tblsz;
 129
 130                         inode->i_fop = &mqueue_file_operations;
 131                         inode->i_size = FILENT_SIZE;
 132                         /* mqueue specific info */
 133                         info = MQUEUE_I(inode);
 134                         spin_lock_init(&info->lock);
 135                         init_waitqueue_head(&info->wait_q);
 136                         INIT_LIST_HEAD(&info->e_wait_q[0].list);
 137                         INIT_LIST_HEAD(&info->e_wait_q[1].list);
 138                         info->notify_owner = NULL;
 139                         info->qsize = 0;
 140                         info->user = NULL;      /* set when all is ok */
 141                         memset(&info->attr, 0, sizeof(info->attr));
 142                         info->attr.mq_maxmsg = ipc_ns->mq_msg_max;
 143                         info->attr.mq_msgsize = ipc_ns->mq_msgsize_max;
 144                         if (attr) {
 145                                 info->attr.mq_maxmsg = attr->mq_maxmsg;
 146                                 info->attr.mq_msgsize = attr->mq_msgsize;
 147                         }
 148                         mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
 149                         info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
 150                         if (!info->messages)
 151                                 goto out_inode;
 152
 153                         mq_bytes = (mq_msg_tblsz +
 154                                 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
 155
 156                         spin_lock(&mq_lock);
 157                         if (u->mq_bytes + mq_bytes < u->mq_bytes ||
 158                             u->mq_bytes + mq_bytes >
 159                             task_rlimit(p, RLIMIT_MSGQUEUE)) {
 160                                 spin_unlock(&mq_lock);
 161                                 /* mqueue_evict_inode() releases info->messages */
 162                                 goto out_inode;
 163                         }
 164                         u->mq_bytes += mq_bytes;
 165                         spin_unlock(&mq_lock);
 166
 167                         /* all is ok */
 168                         info->user = get_uid(u);
 169                 } else if (S_ISDIR(mode)) {
 170                         inc_nlink(inode);
 171                         /* Some things misbehave if size == 0 on a directory */
 172                         inode->i_size = 2 * DIRENT_SIZE;
 173                         inode->i_op = &mqueue_dir_inode_operations;
 174                         inode->i_fop = &simple_dir_operations;
 175                 }
 176         }
 177         return inode;
 178 out_inode:
 179         iput(inode);
 180         return NULL;
 181 }
 182
 183 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
 184 {
 185         struct inode *inode;
 186         struct ipc_namespace *ns = data;
 187         int error;
 188
 189         sb->s_blocksize = PAGE_CACHE_SIZE;
 190         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 191         sb->s_magic = MQUEUE_MAGIC;
 192         sb->s_op = &mqueue_super_ops;
 193
 194         inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO,
 195                                 NULL);
 196         if (!inode) {
 197                 error = -ENOMEM;
 198                 goto out;
 199         }
 200
 201         sb->s_root = d_alloc_root(inode);
 202         if (!sb->s_root) {
 203                 iput(inode);
 204                 error = -ENOMEM;
 205                 goto out;
 206         }
 207         error = 0;
 208
 209 out:
 210         return error;
 211 }
 212
 213 static int mqueue_get_sb(struct file_system_type *fs_type,
 214                          int flags, const char *dev_name,
 215                          void *data, struct vfsmount *mnt)
 216 {
 217         if (!(flags & MS_KERNMOUNT))
 218                 data = current->nsproxy->ipc_ns;
 219         return get_sb_ns(fs_type, flags, data, mqueue_fill_super, mnt);
 220 }
 221
 222 static void init_once(void *foo)
 223 {
 224         struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
 225
 226         inode_init_once(&p->vfs_inode);
 227 }
 228
 229 static struct inode *mqueue_alloc_inode(struct super_block *sb)
 230 {
 231         struct mqueue_inode_info *ei;
 232
 233         ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
 234         if (!ei)
 235                 return NULL;
 236         return &ei->vfs_inode;
 237 }
 238
 239 static void mqueue_destroy_inode(struct inode *inode)
 240 {
 241         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
 242 }
 243
 244 static void mqueue_evict_inode(struct inode *inode)
 245 {
 246         struct mqueue_inode_info *info;
 247         struct user_struct *user;
 248         unsigned long mq_bytes;
 249         int i;
 250         struct ipc_namespace *ipc_ns;
 251
 252         end_writeback(inode);
 253
 254         if (S_ISDIR(inode->i_mode))
 255                 return;
 256
 257         ipc_ns = get_ns_from_inode(inode);
 258         info = MQUEUE_I(inode);
 259         spin_lock(&info->lock);
 260         for (i = 0; i < info->attr.mq_curmsgs; i++)
 261                 free_msg(info->messages[i]);
 262         kfree(info->messages);
 263         spin_unlock(&info->lock);
 264
 265         /* Total amount of bytes accounted for the mqueue */
 266         mq_bytes = info->attr.mq_maxmsg * (sizeof(struct msg_msg *)
 267             + info->attr.mq_msgsize);
 268         user = info->user;
 269         if (user) {
 270                 spin_lock(&mq_lock);
 271                 user->mq_bytes -= mq_bytes;
 272                 /*
 273                  * get_ns_from_inode() ensures that the
 274                  * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
 275                  * to which we now hold a reference, or it is NULL.
 276                  * We can't put it here under mq_lock, though.
 277                  */
 278                 if (ipc_ns)
 279                         ipc_ns->mq_queues_count--;
 280                 spin_unlock(&mq_lock);
 281                 free_uid(user);
 282         }
 283         if (ipc_ns)
 284                 put_ipc_ns(ipc_ns);
 285 }
 286
 287 static int mqueue_create(struct inode *dir, struct dentry *dentry,
 288                                 int mode, struct nameidata *nd)
 289 {
 290         struct inode *inode;
 291         struct mq_attr *attr = dentry->d_fsdata;
 292         int error;
 293         struct ipc_namespace *ipc_ns;
 294
 295         spin_lock(&mq_lock);
 296         ipc_ns = __get_ns_from_inode(dir);
 297         if (!ipc_ns) {
 298                 error = -EACCES;
 299                 goto out_unlock;
 300         }
 301         if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
 302                         !capable(CAP_SYS_RESOURCE)) {
 303                 error = -ENOSPC;
 304                 goto out_unlock;
 305         }
 306         ipc_ns->mq_queues_count++;
 307         spin_unlock(&mq_lock);
 308
 309         inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
 310         if (!inode) {
 311                 error = -ENOMEM;
 312                 spin_lock(&mq_lock);
 313                 ipc_ns->mq_queues_count--;
 314                 goto out_unlock;
 315         }
 316
 317         put_ipc_ns(ipc_ns);
 318         dir->i_size += DIRENT_SIZE;
 319         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 320
 321         d_instantiate(dentry, inode);
 322         dget(dentry);
 323         return 0;
 324 out_unlock:
 325         spin_unlock(&mq_lock);
 326         if (ipc_ns)
 327                 put_ipc_ns(ipc_ns);
 328         return error;
 329 }
 330
 331 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
 332 {
 333         struct inode *inode = dentry->d_inode;
 334
 335         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 336         dir->i_size -= DIRENT_SIZE;
 337         drop_nlink(inode);
 338         dput(dentry);
 339         return 0;
 340 }
 341
 342 /*
 343 *       This is routine for system read from queue file.
 344 *       To avoid mess with doing here some sort of mq_receive we allow
 345 *       to read only queue size & notification info (the only values
 346 *       that are interesting from user point of view and aren't accessible
 347 *       through std routines)
 348 */
 349 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
 350                                 size_t count, loff_t *off)
 351 {
 352         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 353         char buffer[FILENT_SIZE];
 354         ssize_t ret;
 355
 356         spin_lock(&info->lock);
 357         snprintf(buffer, sizeof(buffer),
 358                         "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
 359                         info->qsize,
 360                         info->notify_owner ? info->notify.sigev_notify : 0,
 361                         (info->notify_owner &&
 362                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
 363                                 info->notify.sigev_signo : 0,
 364                         pid_vnr(info->notify_owner));
 365         spin_unlock(&info->lock);
 366         buffer[sizeof(buffer)-1] = '\0';
 367
 368         ret = simple_read_from_buffer(u_data, count, off, buffer,
 369                                 strlen(buffer));
 370         if (ret <= 0)
 371                 return ret;
 372
 373         filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
 374         return ret;
 375 }
 376
 377 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
 378 {
 379         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 380
 381         spin_lock(&info->lock);
 382         if (task_tgid(current) == info->notify_owner)
 383                 remove_notification(info);
 384
 385         spin_unlock(&info->lock);
 386         return 0;
 387 }
 388
 389 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
 390 {
 391         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 392         int retval = 0;
 393
 394         poll_wait(filp, &info->wait_q, poll_tab);
 395
 396         spin_lock(&info->lock);
 397         if (info->attr.mq_curmsgs)
 398                 retval = POLLIN | POLLRDNORM;
 399
 400         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
 401                 retval |= POLLOUT | POLLWRNORM;
 402         spin_unlock(&info->lock);
 403
 404         return retval;
 405 }
 406
 407 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
 408 static void wq_add(struct mqueue_inode_info *info, int sr,
 409                         struct ext_wait_queue *ewp)
 410 {
 411         struct ext_wait_queue *walk;
 412
 413         ewp->task = current;
 414
 415         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
 416                 if (walk->task->static_prio <= current->static_prio) {
 417                         list_add_tail(&ewp->list, &walk->list);
 418                         return;
 419                 }
 420         }
 421         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
 422 }
 423
 424 /*
 425  * Puts current task to sleep. Caller must hold queue lock. After return
 426  * lock isn't held.
 427  * sr: SEND or RECV
 428  */
 429 static int wq_sleep(struct mqueue_inode_info *info, int sr,
 430                     ktime_t *timeout, struct ext_wait_queue *ewp)
 431 {
 432         int retval;
 433         signed long time;
 434
 435         wq_add(info, sr, ewp);
 436
 437         for (;;) {
 438                 set_current_state(TASK_INTERRUPTIBLE);
 439
 440                 spin_unlock(&info->lock);
 441                 time = schedule_hrtimeout_range_clock(timeout,
 442                     HRTIMER_MODE_ABS, 0, CLOCK_REALTIME);
 443
 444                 while (ewp->state == STATE_PENDING)
 445                         cpu_relax();
 446
 447                 if (ewp->state == STATE_READY) {
 448                         retval = 0;
 449                         goto out;
 450                 }
 451                 spin_lock(&info->lock);
 452                 if (ewp->state == STATE_READY) {
 453                         retval = 0;
 454                         goto out_unlock;
 455                 }
 456                 if (signal_pending(current)) {
 457                         retval = -ERESTARTSYS;
 458                         break;
 459                 }
 460                 if (time == 0) {
 461                         retval = -ETIMEDOUT;
 462                         break;
 463                 }
 464         }
 465         list_del(&ewp->list);
 466 out_unlock:
 467         spin_unlock(&info->lock);
 468 out:
 469         return retval;
 470 }
 471
 472 /*
 473  * Returns waiting task that should be serviced first or NULL if none exists
 474  */
 475 static struct ext_wait_queue *wq_get_first_waiter(
 476                 struct mqueue_inode_info *info, int sr)
 477 {
 478         struct list_head *ptr;
 479
 480         ptr = info->e_wait_q[sr].list.prev;
 481         if (ptr == &info->e_wait_q[sr].list)
 482                 return NULL;
 483         return list_entry(ptr, struct ext_wait_queue, list);
 484 }
 485
 486 /* Auxiliary functions to manipulate messages' list */
 487 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
 488 {
 489         int k;
 490
 491         k = info->attr.mq_curmsgs - 1;
 492         while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
 493                 info->messages[k + 1] = info->messages[k];
 494                 k--;
 495         }
 496         info->attr.mq_curmsgs++;
 497         info->qsize += ptr->m_ts;
 498         info->messages[k + 1] = ptr;
 499 }
 500
 501 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
 502 {
 503         info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
 504         return info->messages[info->attr.mq_curmsgs];
 505 }
 506
 507 static inline void set_cookie(struct sk_buff *skb, char code)
 508 {
 509         ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
 510 }
 511
 512 /*
 513  * The next function is only to split too long sys_mq_timedsend
 514  */
 515 static void __do_notify(struct mqueue_inode_info *info)
 516 {
 517         /* notification
 518          * invoked when there is registered process and there isn't process
 519          * waiting synchronously for message AND state of queue changed from
 520          * empty to not empty. Here we are sure that no one is waiting
 521          * synchronously. */
 522         if (info->notify_owner &&
 523             info->attr.mq_curmsgs == 1) {
 524                 struct siginfo sig_i;
 525                 switch (info->notify.sigev_notify) {
 526                 case SIGEV_NONE:
 527                         break;
 528                 case SIGEV_SIGNAL:
 529                         /* sends signal */
 530
 531                         sig_i.si_signo = info->notify.sigev_signo;
 532                         sig_i.si_errno = 0;
 533                         sig_i.si_code = SI_MESGQ;
 534                         sig_i.si_value = info->notify.sigev_value;
 535                         sig_i.si_pid = task_tgid_nr_ns(current,
 536                                                 ns_of_pid(info->notify_owner));
 537                         sig_i.si_uid = current_uid();
 538
 539                         kill_pid_info(info->notify.sigev_signo,
 540                                       &sig_i, info->notify_owner);
 541                         break;
 542                 case SIGEV_THREAD:
 543                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
 544                         netlink_sendskb(info->notify_sock, info->notify_cookie);
 545                         break;
 546                 }
 547                 /* after notification unregisters process */
 548                 put_pid(info->notify_owner);
 549                 info->notify_owner = NULL;
 550         }
 551         wake_up(&info->wait_q);
 552 }
 553
 554 static int prepare_timeout(const struct timespec __user *u_abs_timeout,
 555                            ktime_t *expires, struct timespec *ts)
 556 {
 557         if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec)))
 558                 return -EFAULT;
 559         if (!timespec_valid(ts))
 560                 return -EINVAL;
 561
 562         *expires = timespec_to_ktime(*ts);
 563         return 0;
 564 }
 565
 566 static void remove_notification(struct mqueue_inode_info *info)
 567 {
 568         if (info->notify_owner != NULL &&
 569             info->notify.sigev_notify == SIGEV_THREAD) {
 570                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
 571                 netlink_sendskb(info->notify_sock, info->notify_cookie);
 572         }
 573         put_pid(info->notify_owner);
 574         info->notify_owner = NULL;
 575 }
 576
 577 static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
 578 {
 579         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
 580                 return 0;
 581         if (capable(CAP_SYS_RESOURCE)) {
 582                 if (attr->mq_maxmsg > HARD_MSGMAX)
 583                         return 0;
 584         } else {
 585                 if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
 586                                 attr->mq_msgsize > ipc_ns->mq_msgsize_max)
 587                         return 0;
 588         }
 589         /* check for overflow */
 590         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
 591                 return 0;
 592         if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize
 593             + sizeof (struct msg_msg *))) <
 594             (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
 595                 return 0;
 596         return 1;
 597 }
 598
 599 /*
 600  * Invoked when creating a new queue via sys_mq_open
 601  */
 602 static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir,
 603                         struct dentry *dentry, int oflag, mode_t mode,
 604                         struct mq_attr *attr)
 605 {
 606         const struct cred *cred = current_cred();
 607         struct file *result;
 608         int ret;
 609
 610         if (attr) {
 611                 if (!mq_attr_ok(ipc_ns, attr)) {
 612                         ret = -EINVAL;
 613                         goto out;
 614                 }
 615                 /* store for use during create */
 616                 dentry->d_fsdata = attr;
 617         }
 618
 619         mode &= ~current_umask();
 620         ret = mnt_want_write(ipc_ns->mq_mnt);
 621         if (ret)
 622                 goto out;
 623         ret = vfs_create(dir->d_inode, dentry, mode, NULL);
 624         dentry->d_fsdata = NULL;
 625         if (ret)
 626                 goto out_drop_write;
 627
 628         result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
 629         /*
 630          * dentry_open() took a persistent mnt_want_write(),
 631          * so we can now drop this one.
 632          */
 633         mnt_drop_write(ipc_ns->mq_mnt);
 634         return result;
 635
 636 out_drop_write:
 637         mnt_drop_write(ipc_ns->mq_mnt);
 638 out:
 639         dput(dentry);
 640         mntput(ipc_ns->mq_mnt);
 641         return ERR_PTR(ret);
 642 }
 643
 644 /* Opens existing queue */
 645 static struct file *do_open(struct ipc_namespace *ipc_ns,
 646                                 struct dentry *dentry, int oflag)
 647 {
 648         int ret;
 649         const struct cred *cred = current_cred();
 650
 651         static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
 652                                                   MAY_READ | MAY_WRITE };
 653
 654         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
 655                 ret = -EINVAL;
 656                 goto err;
 657         }
 658
 659         if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
 660                 ret = -EACCES;
 661                 goto err;
 662         }
 663
 664         return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
 665
 666 err:
 667         dput(dentry);
 668         mntput(ipc_ns->mq_mnt);
 669         return ERR_PTR(ret);
 670 }
 671
 672 SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, mode_t, mode,
 673                 struct mq_attr __user *, u_attr)
 674 {
 675         struct dentry *dentry;
 676         struct file *filp;
 677         char *name;
 678         struct mq_attr attr;
 679         int fd, error;
 680         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
 681
 682         if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
 683                 return -EFAULT;
 684
 685         audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
 686
 687         if (IS_ERR(name = getname(u_name)))
 688                 return PTR_ERR(name);
 689
 690         fd = get_unused_fd_flags(O_CLOEXEC);
 691         if (fd < 0)
 692                 goto out_putname;
 693
 694         mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 695         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
 696         if (IS_ERR(dentry)) {
 697                 error = PTR_ERR(dentry);
 698                 goto out_putfd;
 699         }
 700         mntget(ipc_ns->mq_mnt);
 701
 702         if (oflag & O_CREAT) {
 703                 if (dentry->d_inode) {  /* entry already exists */
 704                         audit_inode(name, dentry);
 705                         if (oflag & O_EXCL) {
 706                                 error = -EEXIST;
 707                                 goto out;
 708                         }
 709                         filp = do_open(ipc_ns, dentry, oflag);
 710                 } else {
 711                         filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root,
 712                                                 dentry, oflag, mode,
 713                                                 u_attr ? &attr : NULL);
 714                 }
 715         } else {
 716                 if (!dentry->d_inode) {
 717                         error = -ENOENT;
 718                         goto out;
 719                 }
 720                 audit_inode(name, dentry);
 721                 filp = do_open(ipc_ns, dentry, oflag);
 722         }
 723
 724         if (IS_ERR(filp)) {
 725                 error = PTR_ERR(filp);
 726                 goto out_putfd;
 727         }
 728
 729         fd_install(fd, filp);
 730         goto out_upsem;
 731
 732 out:
 733         dput(dentry);
 734         mntput(ipc_ns->mq_mnt);
 735 out_putfd:
 736         put_unused_fd(fd);
 737         fd = error;
 738 out_upsem:
 739         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 740 out_putname:
 741         putname(name);
 742         return fd;
 743 }
 744
 745 SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
 746 {
 747         int err;
 748         char *name;
 749         struct dentry *dentry;
 750         struct inode *inode = NULL;
 751         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
 752
 753         name = getname(u_name);
 754         if (IS_ERR(name))
 755                 return PTR_ERR(name);
 756
 757         mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
 758                         I_MUTEX_PARENT);
 759         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
 760         if (IS_ERR(dentry)) {
 761                 err = PTR_ERR(dentry);
 762                 goto out_unlock;
 763         }
 764
 765         if (!dentry->d_inode) {
 766                 err = -ENOENT;
 767                 goto out_err;
 768         }
 769
 770         inode = dentry->d_inode;
 771         if (inode)
 772                 atomic_inc(&inode->i_count);
 773         err = mnt_want_write(ipc_ns->mq_mnt);
 774         if (err)
 775                 goto out_err;
 776         err = vfs_unlink(dentry->d_parent->d_inode, dentry);
 777         mnt_drop_write(ipc_ns->mq_mnt);
 778 out_err:
 779         dput(dentry);
 780
 781 out_unlock:
 782         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 783         putname(name);
 784         if (inode)
 785                 iput(inode);
 786
 787         return err;
 788 }
 789
 790 /* Pipelined send and receive functions.
 791  *
 792  * If a receiver finds no waiting message, then it registers itself in the
 793  * list of waiting receivers. A sender checks that list before adding the new
 794  * message into the message array. If there is a waiting receiver, then it
 795  * bypasses the message array and directly hands the message over to the
 796  * receiver.
 797  * The receiver accepts the message and returns without grabbing the queue
 798  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
 799  * are necessary. The same algorithm is used for sysv semaphores, see
 800  * ipc/sem.c for more details.
 801  *
 802  * The same algorithm is used for senders.
 803  */
 804
 805 /* pipelined_send() - send a message directly to the task waiting in
 806  * sys_mq_timedreceive() (without inserting message into a queue).
 807  */
 808 static inline void pipelined_send(struct mqueue_inode_info *info,
 809                                   struct msg_msg *message,
 810                                   struct ext_wait_queue *receiver)
 811 {
 812         receiver->msg = message;
 813         list_del(&receiver->list);
 814         receiver->state = STATE_PENDING;
 815         wake_up_process(receiver->task);
 816         smp_wmb();
 817         receiver->state = STATE_READY;
 818 }
 819
 820 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
 821  * gets its message and put to the queue (we have one free place for sure). */
 822 static inline void pipelined_receive(struct mqueue_inode_info *info)
 823 {
 824         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
 825
 826         if (!sender) {
 827                 /* for poll */
 828                 wake_up_interruptible(&info->wait_q);
 829                 return;
 830         }
 831         msg_insert(sender->msg, info);
 832         list_del(&sender->list);
 833         sender->state = STATE_PENDING;
 834         wake_up_process(sender->task);
 835         smp_wmb();
 836         sender->state = STATE_READY;
 837 }
 838
 839 SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
 840                 size_t, msg_len, unsigned int, msg_prio,
 841                 const struct timespec __user *, u_abs_timeout)
 842 {
 843         struct file *filp;
 844         struct inode *inode;
 845         struct ext_wait_queue wait;
 846         struct ext_wait_queue *receiver;
 847         struct msg_msg *msg_ptr;
 848         struct mqueue_inode_info *info;
 849         ktime_t expires, *timeout = NULL;
 850         struct timespec ts;
 851         int ret;
 852
 853         if (u_abs_timeout) {
 854                 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
 855                 if (res)
 856                         return res;
 857                 timeout = &expires;
 858         }
 859
 860         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
 861                 return -EINVAL;
 862
 863         audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL);
 864
 865         filp = fget(mqdes);
 866         if (unlikely(!filp)) {
 867                 ret = -EBADF;
 868                 goto out;
 869         }
 870
 871         inode = filp->f_path.dentry->d_inode;
 872         if (unlikely(filp->f_op != &mqueue_file_operations)) {
 873                 ret = -EBADF;
 874                 goto out_fput;
 875         }
 876         info = MQUEUE_I(inode);
 877         audit_inode(NULL, filp->f_path.dentry);
 878
 879         if (unlikely(!(filp->f_mode & FMODE_WRITE))) {
 880                 ret = -EBADF;
 881                 goto out_fput;
 882         }
 883
 884         if (unlikely(msg_len > info->attr.mq_msgsize)) {
 885                 ret = -EMSGSIZE;
 886                 goto out_fput;
 887         }
 888
 889         /* First try to allocate memory, before doing anything with
 890          * existing queues. */
 891         msg_ptr = load_msg(u_msg_ptr, msg_len);
 892         if (IS_ERR(msg_ptr)) {
 893                 ret = PTR_ERR(msg_ptr);
 894                 goto out_fput;
 895         }
 896         msg_ptr->m_ts = msg_len;
 897         msg_ptr->m_type = msg_prio;
 898
 899         spin_lock(&info->lock);
 900
 901         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
 902                 if (filp->f_flags & O_NONBLOCK) {
 903                         spin_unlock(&info->lock);
 904                         ret = -EAGAIN;
 905                 } else {
 906                         wait.task = current;
 907                         wait.msg = (void *) msg_ptr;
 908                         wait.state = STATE_NONE;
 909                         ret = wq_sleep(info, SEND, timeout, &wait);
 910                 }
 911                 if (ret < 0)
 912                         free_msg(msg_ptr);
 913         } else {
 914                 receiver = wq_get_first_waiter(info, RECV);
 915                 if (receiver) {
 916                         pipelined_send(info, msg_ptr, receiver);
 917                 } else {
 918                         /* adds message to the queue */
 919                         msg_insert(msg_ptr, info);
 920                         __do_notify(info);
 921                 }
 922                 inode->i_atime = inode->i_mtime = inode->i_ctime =
 923                                 CURRENT_TIME;
 924                 spin_unlock(&info->lock);
 925                 ret = 0;
 926         }
 927 out_fput:
 928         fput(filp);
 929 out:
 930         return ret;
 931 }
 932
 933 SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
 934                 size_t, msg_len, unsigned int __user *, u_msg_prio,
 935                 const struct timespec __user *, u_abs_timeout)
 936 {
 937         ssize_t ret;
 938         struct msg_msg *msg_ptr;
 939         struct file *filp;
 940         struct inode *inode;
 941         struct mqueue_inode_info *info;
 942         struct ext_wait_queue wait;
 943         ktime_t expires, *timeout = NULL;
 944         struct timespec ts;
 945
 946         if (u_abs_timeout) {
 947                 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
 948                 if (res)
 949                         return res;
 950                 timeout = &expires;
 951         }
 952
 953         audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
 954
 955         filp = fget(mqdes);
 956         if (unlikely(!filp)) {
 957                 ret = -EBADF;
 958                 goto out;
 959         }
 960
 961         inode = filp->f_path.dentry->d_inode;
 962         if (unlikely(filp->f_op != &mqueue_file_operations)) {
 963                 ret = -EBADF;
 964                 goto out_fput;
 965         }
 966         info = MQUEUE_I(inode);
 967         audit_inode(NULL, filp->f_path.dentry);
 968
 969         if (unlikely(!(filp->f_mode & FMODE_READ))) {
 970                 ret = -EBADF;
 971                 goto out_fput;
 972         }
 973
 974         /* checks if buffer is big enough */
 975         if (unlikely(msg_len < info->attr.mq_msgsize)) {
 976                 ret = -EMSGSIZE;
 977                 goto out_fput;
 978         }
 979
 980         spin_lock(&info->lock);
 981         if (info->attr.mq_curmsgs == 0) {
 982                 if (filp->f_flags & O_NONBLOCK) {
 983                         spin_unlock(&info->lock);
 984                         ret = -EAGAIN;
 985                 } else {
 986                         wait.task = current;
 987                         wait.state = STATE_NONE;
 988                         ret = wq_sleep(info, RECV, timeout, &wait);
 989                         msg_ptr = wait.msg;
 990                 }
 991         } else {
 992                 msg_ptr = msg_get(info);
 993
 994                 inode->i_atime = inode->i_mtime = inode->i_ctime =
 995                                 CURRENT_TIME;
 996
 997                 /* There is now free space in queue. */
 998                 pipelined_receive(info);
 999                 spin_unlock(&info->lock);
1000                 ret = 0;
1001         }
1002         if (ret == 0) {
1003                 ret = msg_ptr->m_ts;
1004
1005                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1006                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1007                         ret = -EFAULT;
1008                 }
1009                 free_msg(msg_ptr);
1010         }
1011 out_fput:
1012         fput(filp);
1013 out:
1014         return ret;
1015 }
1016
1017 /*
1018  * Notes: the case when user wants us to deregister (with NULL as pointer)
1019  * and he isn't currently owner of notification, will be silently discarded.
1020  * It isn't explicitly defined in the POSIX.
1021  */
1022 SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1023                 const struct sigevent __user *, u_notification)
1024 {
1025         int ret;
1026         struct file *filp;
1027         struct sock *sock;
1028         struct inode *inode;
1029         struct sigevent notification;
1030         struct mqueue_inode_info *info;
1031         struct sk_buff *nc;
1032
1033         if (u_notification) {
1034                 if (copy_from_user(&notification, u_notification,
1035                                         sizeof(struct sigevent)))
1036                         return -EFAULT;
1037         }
1038
1039         audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1040
1041         nc = NULL;
1042         sock = NULL;
1043         if (u_notification != NULL) {
1044                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1045                              notification.sigev_notify != SIGEV_SIGNAL &&
1046                              notification.sigev_notify != SIGEV_THREAD))
1047                         return -EINVAL;
1048                 if (notification.sigev_notify == SIGEV_SIGNAL &&
1049                         !valid_signal(notification.sigev_signo)) {
1050                         return -EINVAL;
1051                 }
1052                 if (notification.sigev_notify == SIGEV_THREAD) {
1053                         long timeo;
1054
1055                         /* create the notify skb */
1056                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1057                         if (!nc) {
1058                                 ret = -ENOMEM;
1059                                 goto out;
1060                         }
1061                         if (copy_from_user(nc->data,
1062                                         notification.sigev_value.sival_ptr,
1063                                         NOTIFY_COOKIE_LEN)) {
1064                                 ret = -EFAULT;
1065                                 goto out;
1066                         }
1067
1068                         /* TODO: add a header? */
1069                         skb_put(nc, NOTIFY_COOKIE_LEN);
1070                         /* and attach it to the socket */
1071 retry:
1072                         filp = fget(notification.sigev_signo);
1073                         if (!filp) {
1074                                 ret = -EBADF;
1075                                 goto out;
1076                         }
1077                         sock = netlink_getsockbyfilp(filp);
1078                         fput(filp);
1079                         if (IS_ERR(sock)) {
1080                                 ret = PTR_ERR(sock);
1081                                 sock = NULL;
1082                                 goto out;
1083                         }
1084
1085                         timeo = MAX_SCHEDULE_TIMEOUT;
1086                         ret = netlink_attachskb(sock, nc, &timeo, NULL);
1087                         if (ret == 1)
1088                                 goto retry;
1089                         if (ret) {
1090                                 sock = NULL;
1091                                 nc = NULL;
1092                                 goto out;
1093                         }
1094                 }
1095         }
1096
1097         filp = fget(mqdes);
1098         if (!filp) {
1099                 ret = -EBADF;
1100                 goto out;
1101         }
1102
1103         inode = filp->f_path.dentry->d_inode;
1104         if (unlikely(filp->f_op != &mqueue_file_operations)) {
1105                 ret = -EBADF;
1106                 goto out_fput;
1107         }
1108         info = MQUEUE_I(inode);
1109
1110         ret = 0;
1111         spin_lock(&info->lock);
1112         if (u_notification == NULL) {
1113                 if (info->notify_owner == task_tgid(current)) {
1114                         remove_notification(info);
1115                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1116                 }
1117         } else if (info->notify_owner != NULL) {
1118                 ret = -EBUSY;
1119         } else {
1120                 switch (notification.sigev_notify) {
1121                 case SIGEV_NONE:
1122                         info->notify.sigev_notify = SIGEV_NONE;
1123                         break;
1124                 case SIGEV_THREAD:
1125                         info->notify_sock = sock;
1126                         info->notify_cookie = nc;
1127                         sock = NULL;
1128                         nc = NULL;
1129                         info->notify.sigev_notify = SIGEV_THREAD;
1130                         break;
1131                 case SIGEV_SIGNAL:
1132                         info->notify.sigev_signo = notification.sigev_signo;
1133                         info->notify.sigev_value = notification.sigev_value;
1134                         info->notify.sigev_notify = SIGEV_SIGNAL;
1135                         break;
1136                 }
1137
1138                 info->notify_owner = get_pid(task_tgid(current));
1139                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1140         }
1141         spin_unlock(&info->lock);
1142 out_fput:
1143         fput(filp);
1144 out:
1145         if (sock) {
1146                 netlink_detachskb(sock, nc);
1147         } else if (nc) {
1148                 dev_kfree_skb(nc);
1149         }
1150         return ret;
1151 }
1152
1153 SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1154                 const struct mq_attr __user *, u_mqstat,
1155                 struct mq_attr __user *, u_omqstat)
1156 {
1157         int ret;
1158         struct mq_attr mqstat, omqstat;
1159         struct file *filp;
1160         struct inode *inode;
1161         struct mqueue_inode_info *info;
1162
1163         if (u_mqstat != NULL) {
1164                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1165                         return -EFAULT;
1166                 if (mqstat.mq_flags & (~O_NONBLOCK))
1167                         return -EINVAL;
1168         }
1169
1170         filp = fget(mqdes);
1171         if (!filp) {
1172                 ret = -EBADF;
1173                 goto out;
1174         }
1175
1176         inode = filp->f_path.dentry->d_inode;
1177         if (unlikely(filp->f_op != &mqueue_file_operations)) {
1178                 ret = -EBADF;
1179                 goto out_fput;
1180         }
1181         info = MQUEUE_I(inode);
1182
1183         spin_lock(&info->lock);
1184
1185         omqstat = info->attr;
1186         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1187         if (u_mqstat) {
1188                 audit_mq_getsetattr(mqdes, &mqstat);
1189                 spin_lock(&filp->f_lock);
1190                 if (mqstat.mq_flags & O_NONBLOCK)
1191                         filp->f_flags |= O_NONBLOCK;
1192                 else
1193                         filp->f_flags &= ~O_NONBLOCK;
1194                 spin_unlock(&filp->f_lock);
1195
1196                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1197         }
1198
1199         spin_unlock(&info->lock);
1200
1201         ret = 0;
1202         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1203                                                 sizeof(struct mq_attr)))
1204                 ret = -EFAULT;
1205
1206 out_fput:
1207         fput(filp);
1208 out:
1209         return ret;
1210 }
1211
1212 static const struct inode_operations mqueue_dir_inode_operations = {
1213         .lookup = simple_lookup,
1214         .create = mqueue_create,
1215         .unlink = mqueue_unlink,
1216 };
1217
1218 static const struct file_operations mqueue_file_operations = {
1219         .flush = mqueue_flush_file,
1220         .poll = mqueue_poll_file,
1221         .read = mqueue_read_file,
1222 };
1223
1224 static const struct super_operations mqueue_super_ops = {
1225         .alloc_inode = mqueue_alloc_inode,
1226         .destroy_inode = mqueue_destroy_inode,
1227         .evict_inode = mqueue_evict_inode,
1228         .statfs = simple_statfs,
1229 };
1230
1231 static struct file_system_type mqueue_fs_type = {
1232         .name = "mqueue",
1233         .get_sb = mqueue_get_sb,
1234         .kill_sb = kill_litter_super,
1235 };
1236
1237 int mq_init_ns(struct ipc_namespace *ns)
1238 {
1239         ns->mq_queues_count  = 0;
1240         ns->mq_queues_max    = DFLT_QUEUESMAX;
1241         ns->mq_msg_max       = DFLT_MSGMAX;
1242         ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1243
1244         ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1245         if (IS_ERR(ns->mq_mnt)) {
1246                 int err = PTR_ERR(ns->mq_mnt);
1247                 ns->mq_mnt = NULL;
1248                 return err;
1249         }
1250         return 0;
1251 }
1252
1253 void mq_clear_sbinfo(struct ipc_namespace *ns)
1254 {
1255         ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1256 }
1257
1258 void mq_put_mnt(struct ipc_namespace *ns)
1259 {
1260         mntput(ns->mq_mnt);
1261 }
1262
1263 static int __init init_mqueue_fs(void)
1264 {
1265         int error;
1266
1267         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1268                                 sizeof(struct mqueue_inode_info), 0,
1269                                 SLAB_HWCACHE_ALIGN, init_once);
1270         if (mqueue_inode_cachep == NULL)
1271                 return -ENOMEM;
1272
1273         /* ignore failures - they are not fatal */
1274         mq_sysctl_table = mq_register_sysctl_table();
1275
1276         error = register_filesystem(&mqueue_fs_type);
1277         if (error)
1278                 goto out_sysctl;
1279
1280         spin_lock_init(&mq_lock);
1281
1282         init_ipc_ns.mq_mnt = kern_mount_data(&mqueue_fs_type, &init_ipc_ns);
1283         if (IS_ERR(init_ipc_ns.mq_mnt)) {
1284                 error = PTR_ERR(init_ipc_ns.mq_mnt);
1285                 goto out_filesystem;
1286         }
1287
1288         return 0;
1289
1290 out_filesystem:
1291         unregister_filesystem(&mqueue_fs_type);
1292 out_sysctl:
1293         if (mq_sysctl_table)
1294                 unregister_sysctl_table(mq_sysctl_table);
1295         kmem_cache_destroy(mqueue_inode_cachep);
1296         return error;
1297 }
1298
1299 __initcall(init_mqueue_fs);