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         int ret = -ENOMEM;
 117
 118         inode = new_inode(sb);
 119         if (!inode)
 120                 goto err;
 121
 122         inode->i_ino = get_next_ino();
 123         inode->i_mode = mode;
 124         inode->i_uid = current_fsuid();
 125         inode->i_gid = current_fsgid();
 126         inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME;
 127
 128         if (S_ISREG(mode)) {
 129                 struct mqueue_inode_info *info;
 130                 struct task_struct *p = current;
 131                 unsigned long mq_bytes, mq_msg_tblsz;
 132
 133                 inode->i_fop = &mqueue_file_operations;
 134                 inode->i_size = FILENT_SIZE;
 135                 /* mqueue specific info */
 136                 info = MQUEUE_I(inode);
 137                 spin_lock_init(&info->lock);
 138                 init_waitqueue_head(&info->wait_q);
 139                 INIT_LIST_HEAD(&info->e_wait_q[0].list);
 140                 INIT_LIST_HEAD(&info->e_wait_q[1].list);
 141                 info->notify_owner = NULL;
 142                 info->qsize = 0;
 143                 info->user = NULL;      /* set when all is ok */
 144                 memset(&info->attr, 0, sizeof(info->attr));
 145                 info->attr.mq_maxmsg = min(ipc_ns->mq_msg_max, DFLT_MSG);
 146                 info->attr.mq_msgsize =
 147                         min(ipc_ns->mq_msgsize_max, DFLT_MSGSIZE);
 148                 if (attr) {
 149                         info->attr.mq_maxmsg = attr->mq_maxmsg;
 150                         info->attr.mq_msgsize = attr->mq_msgsize;
 151                 }
 152                 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
 153                 if (mq_msg_tblsz > KMALLOC_MAX_SIZE)
 154                         info->messages = vmalloc(mq_msg_tblsz);
 155                 else
 156                         info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
 157                 if (!info->messages)
 158                         goto out_inode;
 159
 160                 mq_bytes = (mq_msg_tblsz +
 161                         (info->attr.mq_maxmsg * info->attr.mq_msgsize));
 162
 163                 spin_lock(&mq_lock);
 164                 if (u->mq_bytes + mq_bytes < u->mq_bytes ||
 165                     u->mq_bytes + mq_bytes > task_rlimit(p, RLIMIT_MSGQUEUE)) {
 166                         spin_unlock(&mq_lock);
 167                         /* mqueue_evict_inode() releases info->messages */
 168                         ret = -EMFILE;
 169                         goto out_inode;
 170                 }
 171                 u->mq_bytes += mq_bytes;
 172                 spin_unlock(&mq_lock);
 173
 174                 /* all is ok */
 175                 info->user = get_uid(u);
 176         } else if (S_ISDIR(mode)) {
 177                 inc_nlink(inode);
 178                 /* Some things misbehave if size == 0 on a directory */
 179                 inode->i_size = 2 * DIRENT_SIZE;
 180                 inode->i_op = &mqueue_dir_inode_operations;
 181                 inode->i_fop = &simple_dir_operations;
 182         }
 183
 184         return inode;
 185 out_inode:
 186         iput(inode);
 187 err:
 188         return ERR_PTR(ret);
 189 }
 190
 191 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
 192 {
 193         struct inode *inode;
 194         struct ipc_namespace *ns = data;
 195         int error;
 196
 197         sb->s_blocksize = PAGE_CACHE_SIZE;
 198         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 199         sb->s_magic = MQUEUE_MAGIC;
 200         sb->s_op = &mqueue_super_ops;
 201
 202         inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO,
 203                                 NULL);
 204         if (IS_ERR(inode)) {
 205                 error = PTR_ERR(inode);
 206                 goto out;
 207         }
 208
 209         sb->s_root = d_alloc_root(inode);
 210         if (!sb->s_root) {
 211                 iput(inode);
 212                 error = -ENOMEM;
 213                 goto out;
 214         }
 215         error = 0;
 216
 217 out:
 218         return error;
 219 }
 220
 221 static struct dentry *mqueue_mount(struct file_system_type *fs_type,
 222                          int flags, const char *dev_name,
 223                          void *data)
 224 {
 225         if (!(flags & MS_KERNMOUNT))
 226                 data = current->nsproxy->ipc_ns;
 227         return mount_ns(fs_type, flags, data, mqueue_fill_super);
 228 }
 229
 230 static void init_once(void *foo)
 231 {
 232         struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
 233
 234         inode_init_once(&p->vfs_inode);
 235 }
 236
 237 static struct inode *mqueue_alloc_inode(struct super_block *sb)
 238 {
 239         struct mqueue_inode_info *ei;
 240
 241         ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
 242         if (!ei)
 243                 return NULL;
 244         return &ei->vfs_inode;
 245 }
 246
 247 static void mqueue_i_callback(struct rcu_head *head)
 248 {
 249         struct inode *inode = container_of(head, struct inode, i_rcu);
 250         INIT_LIST_HEAD(&inode->i_dentry);
 251         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
 252 }
 253
 254 static void mqueue_destroy_inode(struct inode *inode)
 255 {
 256         call_rcu(&inode->i_rcu, mqueue_i_callback);
 257 }
 258
 259 static void mqueue_evict_inode(struct inode *inode)
 260 {
 261         struct mqueue_inode_info *info;
 262         struct user_struct *user;
 263         unsigned long mq_bytes;
 264         int i;
 265         struct ipc_namespace *ipc_ns;
 266
 267         end_writeback(inode);
 268
 269         if (S_ISDIR(inode->i_mode))
 270                 return;
 271
 272         ipc_ns = get_ns_from_inode(inode);
 273         info = MQUEUE_I(inode);
 274         spin_lock(&info->lock);
 275         for (i = 0; i < info->attr.mq_curmsgs; i++)
 276                 free_msg(info->messages[i]);
 277         if (info->attr.mq_maxmsg * sizeof(struct msg_msg *) > KMALLOC_MAX_SIZE)
 278                 vfree(info->messages);
 279         else
 280                 kfree(info->messages);
 281         spin_unlock(&info->lock);
 282
 283         /* Total amount of bytes accounted for the mqueue */
 284         mq_bytes = info->attr.mq_maxmsg * (sizeof(struct msg_msg *)
 285             + info->attr.mq_msgsize);
 286         user = info->user;
 287         if (user) {
 288                 spin_lock(&mq_lock);
 289                 user->mq_bytes -= mq_bytes;
 290                 /*
 291                  * get_ns_from_inode() ensures that the
 292                  * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
 293                  * to which we now hold a reference, or it is NULL.
 294                  * We can't put it here under mq_lock, though.
 295                  */
 296                 if (ipc_ns)
 297                         ipc_ns->mq_queues_count--;
 298                 spin_unlock(&mq_lock);
 299                 free_uid(user);
 300         }
 301         if (ipc_ns)
 302                 put_ipc_ns(ipc_ns);
 303 }
 304
 305 static int mqueue_create(struct inode *dir, struct dentry *dentry,
 306                                 int mode, struct nameidata *nd)
 307 {
 308         struct inode *inode;
 309         struct mq_attr *attr = dentry->d_fsdata;
 310         int error;
 311         struct ipc_namespace *ipc_ns;
 312
 313         spin_lock(&mq_lock);
 314         ipc_ns = __get_ns_from_inode(dir);
 315         if (!ipc_ns) {
 316                 error = -EACCES;
 317                 goto out_unlock;
 318         }
 319         if (ipc_ns->mq_queues_count >= HARD_QUEUESMAX ||
 320             (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
 321              !capable(CAP_SYS_RESOURCE))) {
 322                 error = -ENOSPC;
 323                 goto out_unlock;
 324         }
 325         ipc_ns->mq_queues_count++;
 326         spin_unlock(&mq_lock);
 327
 328         inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
 329         if (IS_ERR(inode)) {
 330                 error = PTR_ERR(inode);
 331                 spin_lock(&mq_lock);
 332                 ipc_ns->mq_queues_count--;
 333                 goto out_unlock;
 334         }
 335
 336         put_ipc_ns(ipc_ns);
 337         dir->i_size += DIRENT_SIZE;
 338         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 339
 340         d_instantiate(dentry, inode);
 341         dget(dentry);
 342         return 0;
 343 out_unlock:
 344         spin_unlock(&mq_lock);
 345         if (ipc_ns)
 346                 put_ipc_ns(ipc_ns);
 347         return error;
 348 }
 349
 350 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
 351 {
 352         struct inode *inode = dentry->d_inode;
 353
 354         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 355         dir->i_size -= DIRENT_SIZE;
 356         drop_nlink(inode);
 357         dput(dentry);
 358         return 0;
 359 }
 360
 361 /*
 362 *       This is routine for system read from queue file.
 363 *       To avoid mess with doing here some sort of mq_receive we allow
 364 *       to read only queue size & notification info (the only values
 365 *       that are interesting from user point of view and aren't accessible
 366 *       through std routines)
 367 */
 368 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
 369                                 size_t count, loff_t *off)
 370 {
 371         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 372         char buffer[FILENT_SIZE];
 373         ssize_t ret;
 374
 375         spin_lock(&info->lock);
 376         snprintf(buffer, sizeof(buffer),
 377                         "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
 378                         info->qsize,
 379                         info->notify_owner ? info->notify.sigev_notify : 0,
 380                         (info->notify_owner &&
 381                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
 382                                 info->notify.sigev_signo : 0,
 383                         pid_vnr(info->notify_owner));
 384         spin_unlock(&info->lock);
 385         buffer[sizeof(buffer)-1] = '\0';
 386
 387         ret = simple_read_from_buffer(u_data, count, off, buffer,
 388                                 strlen(buffer));
 389         if (ret <= 0)
 390                 return ret;
 391
 392         filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
 393         return ret;
 394 }
 395
 396 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
 397 {
 398         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 399
 400         spin_lock(&info->lock);
 401         if (task_tgid(current) == info->notify_owner)
 402                 remove_notification(info);
 403
 404         spin_unlock(&info->lock);
 405         return 0;
 406 }
 407
 408 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
 409 {
 410         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 411         int retval = 0;
 412
 413         poll_wait(filp, &info->wait_q, poll_tab);
 414
 415         spin_lock(&info->lock);
 416         if (info->attr.mq_curmsgs)
 417                 retval = POLLIN | POLLRDNORM;
 418
 419         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
 420                 retval |= POLLOUT | POLLWRNORM;
 421         spin_unlock(&info->lock);
 422
 423         return retval;
 424 }
 425
 426 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
 427 static void wq_add(struct mqueue_inode_info *info, int sr,
 428                         struct ext_wait_queue *ewp)
 429 {
 430         struct ext_wait_queue *walk;
 431
 432         ewp->task = current;
 433
 434         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
 435                 if (walk->task->static_prio <= current->static_prio) {
 436                         list_add_tail(&ewp->list, &walk->list);
 437                         return;
 438                 }
 439         }
 440         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
 441 }
 442
 443 /*
 444  * Puts current task to sleep. Caller must hold queue lock. After return
 445  * lock isn't held.
 446  * sr: SEND or RECV
 447  */
 448 static int wq_sleep(struct mqueue_inode_info *info, int sr,
 449                     ktime_t *timeout, struct ext_wait_queue *ewp)
 450 {
 451         int retval;
 452         signed long time;
 453
 454         wq_add(info, sr, ewp);
 455
 456         for (;;) {
 457                 set_current_state(TASK_INTERRUPTIBLE);
 458
 459                 spin_unlock(&info->lock);
 460                 time = schedule_hrtimeout_range_clock(timeout,
 461                     HRTIMER_MODE_ABS, 0, CLOCK_REALTIME);
 462
 463                 while (ewp->state == STATE_PENDING)
 464                         cpu_relax();
 465
 466                 if (ewp->state == STATE_READY) {
 467                         retval = 0;
 468                         goto out;
 469                 }
 470                 spin_lock(&info->lock);
 471                 if (ewp->state == STATE_READY) {
 472                         retval = 0;
 473                         goto out_unlock;
 474                 }
 475                 if (signal_pending(current)) {
 476                         retval = -ERESTARTSYS;
 477                         break;
 478                 }
 479                 if (time == 0) {
 480                         retval = -ETIMEDOUT;
 481                         break;
 482                 }
 483         }
 484         list_del(&ewp->list);
 485 out_unlock:
 486         spin_unlock(&info->lock);
 487 out:
 488         return retval;
 489 }
 490
 491 /*
 492  * Returns waiting task that should be serviced first or NULL if none exists
 493  */
 494 static struct ext_wait_queue *wq_get_first_waiter(
 495                 struct mqueue_inode_info *info, int sr)
 496 {
 497         struct list_head *ptr;
 498
 499         ptr = info->e_wait_q[sr].list.prev;
 500         if (ptr == &info->e_wait_q[sr].list)
 501                 return NULL;
 502         return list_entry(ptr, struct ext_wait_queue, list);
 503 }
 504
 505 /* Auxiliary functions to manipulate messages' list */
 506 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
 507 {
 508         int k;
 509
 510         k = info->attr.mq_curmsgs - 1;
 511         while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
 512                 info->messages[k + 1] = info->messages[k];
 513                 k--;
 514         }
 515         info->attr.mq_curmsgs++;
 516         info->qsize += ptr->m_ts;
 517         info->messages[k + 1] = ptr;
 518 }
 519
 520 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
 521 {
 522         info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
 523         return info->messages[info->attr.mq_curmsgs];
 524 }
 525
 526 static inline void set_cookie(struct sk_buff *skb, char code)
 527 {
 528         ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
 529 }
 530
 531 /*
 532  * The next function is only to split too long sys_mq_timedsend
 533  */
 534 static void __do_notify(struct mqueue_inode_info *info)
 535 {
 536         /* notification
 537          * invoked when there is registered process and there isn't process
 538          * waiting synchronously for message AND state of queue changed from
 539          * empty to not empty. Here we are sure that no one is waiting
 540          * synchronously. */
 541         if (info->notify_owner &&
 542             info->attr.mq_curmsgs == 1) {
 543                 struct siginfo sig_i;
 544                 switch (info->notify.sigev_notify) {
 545                 case SIGEV_NONE:
 546                         break;
 547                 case SIGEV_SIGNAL:
 548                         /* sends signal */
 549
 550                         sig_i.si_signo = info->notify.sigev_signo;
 551                         sig_i.si_errno = 0;
 552                         sig_i.si_code = SI_MESGQ;
 553                         sig_i.si_value = info->notify.sigev_value;
 554                         sig_i.si_pid = task_tgid_nr_ns(current,
 555                                                 ns_of_pid(info->notify_owner));
 556                         sig_i.si_uid = current_uid();
 557
 558                         kill_pid_info(info->notify.sigev_signo,
 559                                       &sig_i, info->notify_owner);
 560                         break;
 561                 case SIGEV_THREAD:
 562                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
 563                         netlink_sendskb(info->notify_sock, info->notify_cookie);
 564                         break;
 565                 }
 566                 /* after notification unregisters process */
 567                 put_pid(info->notify_owner);
 568                 info->notify_owner = NULL;
 569         }
 570         wake_up(&info->wait_q);
 571 }
 572
 573 static int prepare_timeout(const struct timespec __user *u_abs_timeout,
 574                            ktime_t *expires, struct timespec *ts)
 575 {
 576         if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec)))
 577                 return -EFAULT;
 578         if (!timespec_valid(ts))
 579                 return -EINVAL;
 580
 581         *expires = timespec_to_ktime(*ts);
 582         return 0;
 583 }
 584
 585 static void remove_notification(struct mqueue_inode_info *info)
 586 {
 587         if (info->notify_owner != NULL &&
 588             info->notify.sigev_notify == SIGEV_THREAD) {
 589                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
 590                 netlink_sendskb(info->notify_sock, info->notify_cookie);
 591         }
 592         put_pid(info->notify_owner);
 593         info->notify_owner = NULL;
 594 }
 595
 596 static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
 597 {
 598         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
 599                 return 0;
 600         if (capable(CAP_SYS_RESOURCE)) {
 601                 if (attr->mq_maxmsg > HARD_MSGMAX ||
 602                     attr->mq_msgsize > HARD_MSGSIZEMAX)
 603                         return 0;
 604         } else {
 605                 if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
 606                                 attr->mq_msgsize > ipc_ns->mq_msgsize_max)
 607                         return 0;
 608         }
 609         /* check for overflow */
 610         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
 611                 return 0;
 612         if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize
 613             + sizeof (struct msg_msg *))) <
 614             (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
 615                 return 0;
 616         return 1;
 617 }
 618
 619 /*
 620  * Invoked when creating a new queue via sys_mq_open
 621  */
 622 static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir,
 623                         struct dentry *dentry, int oflag, mode_t mode,
 624                         struct mq_attr *attr)
 625 {
 626         const struct cred *cred = current_cred();
 627         struct file *result;
 628         int ret;
 629
 630         if (attr) {
 631                 if (!mq_attr_ok(ipc_ns, attr)) {
 632                         ret = -EINVAL;
 633                         goto out;
 634                 }
 635                 /* store for use during create */
 636                 dentry->d_fsdata = attr;
 637         }
 638
 639         mode &= ~current_umask();
 640         ret = mnt_want_write(ipc_ns->mq_mnt);
 641         if (ret)
 642                 goto out;
 643         ret = vfs_create(dir->d_inode, dentry, mode, NULL);
 644         dentry->d_fsdata = NULL;
 645         if (ret)
 646                 goto out_drop_write;
 647
 648         result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
 649         /*
 650          * dentry_open() took a persistent mnt_want_write(),
 651          * so we can now drop this one.
 652          */
 653         mnt_drop_write(ipc_ns->mq_mnt);
 654         return result;
 655
 656 out_drop_write:
 657         mnt_drop_write(ipc_ns->mq_mnt);
 658 out:
 659         dput(dentry);
 660         mntput(ipc_ns->mq_mnt);
 661         return ERR_PTR(ret);
 662 }
 663
 664 /* Opens existing queue */
 665 static struct file *do_open(struct ipc_namespace *ipc_ns,
 666                                 struct dentry *dentry, int oflag)
 667 {
 668         int ret;
 669         const struct cred *cred = current_cred();
 670
 671         static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
 672                                                   MAY_READ | MAY_WRITE };
 673
 674         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
 675                 ret = -EINVAL;
 676                 goto err;
 677         }
 678
 679         if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
 680                 ret = -EACCES;
 681                 goto err;
 682         }
 683
 684         return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
 685
 686 err:
 687         dput(dentry);
 688         mntput(ipc_ns->mq_mnt);
 689         return ERR_PTR(ret);
 690 }
 691
 692 SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, mode_t, mode,
 693                 struct mq_attr __user *, u_attr)
 694 {
 695         struct dentry *dentry;
 696         struct file *filp;
 697         char *name;
 698         struct mq_attr attr;
 699         int fd, error;
 700         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
 701
 702         if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
 703                 return -EFAULT;
 704
 705         audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
 706
 707         if (IS_ERR(name = getname(u_name)))
 708                 return PTR_ERR(name);
 709
 710         fd = get_unused_fd_flags(O_CLOEXEC);
 711         if (fd < 0)
 712                 goto out_putname;
 713
 714         mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 715         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
 716         if (IS_ERR(dentry)) {
 717                 error = PTR_ERR(dentry);
 718                 goto out_putfd;
 719         }
 720         mntget(ipc_ns->mq_mnt);
 721
 722         if (oflag & O_CREAT) {
 723                 if (dentry->d_inode) {  /* entry already exists */
 724                         audit_inode(name, dentry);
 725                         if (oflag & O_EXCL) {
 726                                 error = -EEXIST;
 727                                 goto out;
 728                         }
 729                         filp = do_open(ipc_ns, dentry, oflag);
 730                 } else {
 731                         filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root,
 732                                                 dentry, oflag, mode,
 733                                                 u_attr ? &attr : NULL);
 734                 }
 735         } else {
 736                 if (!dentry->d_inode) {
 737                         error = -ENOENT;
 738                         goto out;
 739                 }
 740                 audit_inode(name, dentry);
 741                 filp = do_open(ipc_ns, dentry, oflag);
 742         }
 743
 744         if (IS_ERR(filp)) {
 745                 error = PTR_ERR(filp);
 746                 goto out_putfd;
 747         }
 748
 749         fd_install(fd, filp);
 750         goto out_upsem;
 751
 752 out:
 753         dput(dentry);
 754         mntput(ipc_ns->mq_mnt);
 755 out_putfd:
 756         put_unused_fd(fd);
 757         fd = error;
 758 out_upsem:
 759         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 760 out_putname:
 761         putname(name);
 762         return fd;
 763 }
 764
 765 SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
 766 {
 767         int err;
 768         char *name;
 769         struct dentry *dentry;
 770         struct inode *inode = NULL;
 771         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
 772
 773         name = getname(u_name);
 774         if (IS_ERR(name))
 775                 return PTR_ERR(name);
 776
 777         mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
 778                         I_MUTEX_PARENT);
 779         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
 780         if (IS_ERR(dentry)) {
 781                 err = PTR_ERR(dentry);
 782                 goto out_unlock;
 783         }
 784
 785         if (!dentry->d_inode) {
 786                 err = -ENOENT;
 787                 goto out_err;
 788         }
 789
 790         inode = dentry->d_inode;
 791         if (inode)
 792                 ihold(inode);
 793         err = mnt_want_write(ipc_ns->mq_mnt);
 794         if (err)
 795                 goto out_err;
 796         err = vfs_unlink(dentry->d_parent->d_inode, dentry);
 797         mnt_drop_write(ipc_ns->mq_mnt);
 798 out_err:
 799         dput(dentry);
 800
 801 out_unlock:
 802         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 803         putname(name);
 804         if (inode)
 805                 iput(inode);
 806
 807         return err;
 808 }
 809
 810 /* Pipelined send and receive functions.
 811  *
 812  * If a receiver finds no waiting message, then it registers itself in the
 813  * list of waiting receivers. A sender checks that list before adding the new
 814  * message into the message array. If there is a waiting receiver, then it
 815  * bypasses the message array and directly hands the message over to the
 816  * receiver.
 817  * The receiver accepts the message and returns without grabbing the queue
 818  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
 819  * are necessary. The same algorithm is used for sysv semaphores, see
 820  * ipc/sem.c for more details.
 821  *
 822  * The same algorithm is used for senders.
 823  */
 824
 825 /* pipelined_send() - send a message directly to the task waiting in
 826  * sys_mq_timedreceive() (without inserting message into a queue).
 827  */
 828 static inline void pipelined_send(struct mqueue_inode_info *info,
 829                                   struct msg_msg *message,
 830                                   struct ext_wait_queue *receiver)
 831 {
 832         receiver->msg = message;
 833         list_del(&receiver->list);
 834         receiver->state = STATE_PENDING;
 835         wake_up_process(receiver->task);
 836         smp_wmb();
 837         receiver->state = STATE_READY;
 838 }
 839
 840 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
 841  * gets its message and put to the queue (we have one free place for sure). */
 842 static inline void pipelined_receive(struct mqueue_inode_info *info)
 843 {
 844         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
 845
 846         if (!sender) {
 847                 /* for poll */
 848                 wake_up_interruptible(&info->wait_q);
 849                 return;
 850         }
 851         msg_insert(sender->msg, info);
 852         list_del(&sender->list);
 853         sender->state = STATE_PENDING;
 854         wake_up_process(sender->task);
 855         smp_wmb();
 856         sender->state = STATE_READY;
 857 }
 858
 859 SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
 860                 size_t, msg_len, unsigned int, msg_prio,
 861                 const struct timespec __user *, u_abs_timeout)
 862 {
 863         struct file *filp;
 864         struct inode *inode;
 865         struct ext_wait_queue wait;
 866         struct ext_wait_queue *receiver;
 867         struct msg_msg *msg_ptr;
 868         struct mqueue_inode_info *info;
 869         ktime_t expires, *timeout = NULL;
 870         struct timespec ts;
 871         int ret;
 872
 873         if (u_abs_timeout) {
 874                 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
 875                 if (res)
 876                         return res;
 877                 timeout = &expires;
 878         }
 879
 880         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
 881                 return -EINVAL;
 882
 883         audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL);
 884
 885         filp = fget(mqdes);
 886         if (unlikely(!filp)) {
 887                 ret = -EBADF;
 888                 goto out;
 889         }
 890
 891         inode = filp->f_path.dentry->d_inode;
 892         if (unlikely(filp->f_op != &mqueue_file_operations)) {
 893                 ret = -EBADF;
 894                 goto out_fput;
 895         }
 896         info = MQUEUE_I(inode);
 897         audit_inode(NULL, filp->f_path.dentry);
 898
 899         if (unlikely(!(filp->f_mode & FMODE_WRITE))) {
 900                 ret = -EBADF;
 901                 goto out_fput;
 902         }
 903
 904         if (unlikely(msg_len > info->attr.mq_msgsize)) {
 905                 ret = -EMSGSIZE;
 906                 goto out_fput;
 907         }
 908
 909         /* First try to allocate memory, before doing anything with
 910          * existing queues. */
 911         msg_ptr = load_msg(u_msg_ptr, msg_len);
 912         if (IS_ERR(msg_ptr)) {
 913                 ret = PTR_ERR(msg_ptr);
 914                 goto out_fput;
 915         }
 916         msg_ptr->m_ts = msg_len;
 917         msg_ptr->m_type = msg_prio;
 918
 919         spin_lock(&info->lock);
 920
 921         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
 922                 if (filp->f_flags & O_NONBLOCK) {
 923                         spin_unlock(&info->lock);
 924                         ret = -EAGAIN;
 925                 } else {
 926                         wait.task = current;
 927                         wait.msg = (void *) msg_ptr;
 928                         wait.state = STATE_NONE;
 929                         ret = wq_sleep(info, SEND, timeout, &wait);
 930                 }
 931                 if (ret < 0)
 932                         free_msg(msg_ptr);
 933         } else {
 934                 receiver = wq_get_first_waiter(info, RECV);
 935                 if (receiver) {
 936                         pipelined_send(info, msg_ptr, receiver);
 937                 } else {
 938                         /* adds message to the queue */
 939                         msg_insert(msg_ptr, info);
 940                         __do_notify(info);
 941                 }
 942                 inode->i_atime = inode->i_mtime = inode->i_ctime =
 943                                 CURRENT_TIME;
 944                 spin_unlock(&info->lock);
 945                 ret = 0;
 946         }
 947 out_fput:
 948         fput(filp);
 949 out:
 950         return ret;
 951 }
 952
 953 SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
 954                 size_t, msg_len, unsigned int __user *, u_msg_prio,
 955                 const struct timespec __user *, u_abs_timeout)
 956 {
 957         ssize_t ret;
 958         struct msg_msg *msg_ptr;
 959         struct file *filp;
 960         struct inode *inode;
 961         struct mqueue_inode_info *info;
 962         struct ext_wait_queue wait;
 963         ktime_t expires, *timeout = NULL;
 964         struct timespec ts;
 965
 966         if (u_abs_timeout) {
 967                 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
 968                 if (res)
 969                         return res;
 970                 timeout = &expires;
 971         }
 972
 973         audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
 974
 975         filp = fget(mqdes);
 976         if (unlikely(!filp)) {
 977                 ret = -EBADF;
 978                 goto out;
 979         }
 980
 981         inode = filp->f_path.dentry->d_inode;
 982         if (unlikely(filp->f_op != &mqueue_file_operations)) {
 983                 ret = -EBADF;
 984                 goto out_fput;
 985         }
 986         info = MQUEUE_I(inode);
 987         audit_inode(NULL, filp->f_path.dentry);
 988
 989         if (unlikely(!(filp->f_mode & FMODE_READ))) {
 990                 ret = -EBADF;
 991                 goto out_fput;
 992         }
 993
 994         /* checks if buffer is big enough */
 995         if (unlikely(msg_len < info->attr.mq_msgsize)) {
 996                 ret = -EMSGSIZE;
 997                 goto out_fput;
 998         }
 999
1000         spin_lock(&info->lock);
1001         if (info->attr.mq_curmsgs == 0) {
1002                 if (filp->f_flags & O_NONBLOCK) {
1003                         spin_unlock(&info->lock);
1004                         ret = -EAGAIN;
1005                 } else {
1006                         wait.task = current;
1007                         wait.state = STATE_NONE;
1008                         ret = wq_sleep(info, RECV, timeout, &wait);
1009                         msg_ptr = wait.msg;
1010                 }
1011         } else {
1012                 msg_ptr = msg_get(info);
1013
1014                 inode->i_atime = inode->i_mtime = inode->i_ctime =
1015                                 CURRENT_TIME;
1016
1017                 /* There is now free space in queue. */
1018                 pipelined_receive(info);
1019                 spin_unlock(&info->lock);
1020                 ret = 0;
1021         }
1022         if (ret == 0) {
1023                 ret = msg_ptr->m_ts;
1024
1025                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1026                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1027                         ret = -EFAULT;
1028                 }
1029                 free_msg(msg_ptr);
1030         }
1031 out_fput:
1032         fput(filp);
1033 out:
1034         return ret;
1035 }
1036
1037 /*
1038  * Notes: the case when user wants us to deregister (with NULL as pointer)
1039  * and he isn't currently owner of notification, will be silently discarded.
1040  * It isn't explicitly defined in the POSIX.
1041  */
1042 SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1043                 const struct sigevent __user *, u_notification)
1044 {
1045         int ret;
1046         struct file *filp;
1047         struct sock *sock;
1048         struct inode *inode;
1049         struct sigevent notification;
1050         struct mqueue_inode_info *info;
1051         struct sk_buff *nc;
1052
1053         if (u_notification) {
1054                 if (copy_from_user(&notification, u_notification,
1055                                         sizeof(struct sigevent)))
1056                         return -EFAULT;
1057         }
1058
1059         audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1060
1061         nc = NULL;
1062         sock = NULL;
1063         if (u_notification != NULL) {
1064                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1065                              notification.sigev_notify != SIGEV_SIGNAL &&
1066                              notification.sigev_notify != SIGEV_THREAD))
1067                         return -EINVAL;
1068                 if (notification.sigev_notify == SIGEV_SIGNAL &&
1069                         !valid_signal(notification.sigev_signo)) {
1070                         return -EINVAL;
1071                 }
1072                 if (notification.sigev_notify == SIGEV_THREAD) {
1073                         long timeo;
1074
1075                         /* create the notify skb */
1076                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1077                         if (!nc) {
1078                                 ret = -ENOMEM;
1079                                 goto out;
1080                         }
1081                         if (copy_from_user(nc->data,
1082                                         notification.sigev_value.sival_ptr,
1083                                         NOTIFY_COOKIE_LEN)) {
1084                                 ret = -EFAULT;
1085                                 goto out;
1086                         }
1087
1088                         /* TODO: add a header? */
1089                         skb_put(nc, NOTIFY_COOKIE_LEN);
1090                         /* and attach it to the socket */
1091 retry:
1092                         filp = fget(notification.sigev_signo);
1093                         if (!filp) {
1094                                 ret = -EBADF;
1095                                 goto out;
1096                         }
1097                         sock = netlink_getsockbyfilp(filp);
1098                         fput(filp);
1099                         if (IS_ERR(sock)) {
1100                                 ret = PTR_ERR(sock);
1101                                 sock = NULL;
1102                                 goto out;
1103                         }
1104
1105                         timeo = MAX_SCHEDULE_TIMEOUT;
1106                         ret = netlink_attachskb(sock, nc, &timeo, NULL);
1107                         if (ret == 1)
1108                                 goto retry;
1109                         if (ret) {
1110                                 sock = NULL;
1111                                 nc = NULL;
1112                                 goto out;
1113                         }
1114                 }
1115         }
1116
1117         filp = fget(mqdes);
1118         if (!filp) {
1119                 ret = -EBADF;
1120                 goto out;
1121         }
1122
1123         inode = filp->f_path.dentry->d_inode;
1124         if (unlikely(filp->f_op != &mqueue_file_operations)) {
1125                 ret = -EBADF;
1126                 goto out_fput;
1127         }
1128         info = MQUEUE_I(inode);
1129
1130         ret = 0;
1131         spin_lock(&info->lock);
1132         if (u_notification == NULL) {
1133                 if (info->notify_owner == task_tgid(current)) {
1134                         remove_notification(info);
1135                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1136                 }
1137         } else if (info->notify_owner != NULL) {
1138                 ret = -EBUSY;
1139         } else {
1140                 switch (notification.sigev_notify) {
1141                 case SIGEV_NONE:
1142                         info->notify.sigev_notify = SIGEV_NONE;
1143                         break;
1144                 case SIGEV_THREAD:
1145                         info->notify_sock = sock;
1146                         info->notify_cookie = nc;
1147                         sock = NULL;
1148                         nc = NULL;
1149                         info->notify.sigev_notify = SIGEV_THREAD;
1150                         break;
1151                 case SIGEV_SIGNAL:
1152                         info->notify.sigev_signo = notification.sigev_signo;
1153                         info->notify.sigev_value = notification.sigev_value;
1154                         info->notify.sigev_notify = SIGEV_SIGNAL;
1155                         break;
1156                 }
1157
1158                 info->notify_owner = get_pid(task_tgid(current));
1159                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1160         }
1161         spin_unlock(&info->lock);
1162 out_fput:
1163         fput(filp);
1164 out:
1165         if (sock) {
1166                 netlink_detachskb(sock, nc);
1167         } else if (nc) {
1168                 dev_kfree_skb(nc);
1169         }
1170         return ret;
1171 }
1172
1173 SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1174                 const struct mq_attr __user *, u_mqstat,
1175                 struct mq_attr __user *, u_omqstat)
1176 {
1177         int ret;
1178         struct mq_attr mqstat, omqstat;
1179         struct file *filp;
1180         struct inode *inode;
1181         struct mqueue_inode_info *info;
1182
1183         if (u_mqstat != NULL) {
1184                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1185                         return -EFAULT;
1186                 if (mqstat.mq_flags & (~O_NONBLOCK))
1187                         return -EINVAL;
1188         }
1189
1190         filp = fget(mqdes);
1191         if (!filp) {
1192                 ret = -EBADF;
1193                 goto out;
1194         }
1195
1196         inode = filp->f_path.dentry->d_inode;
1197         if (unlikely(filp->f_op != &mqueue_file_operations)) {
1198                 ret = -EBADF;
1199                 goto out_fput;
1200         }
1201         info = MQUEUE_I(inode);
1202
1203         spin_lock(&info->lock);
1204
1205         omqstat = info->attr;
1206         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1207         if (u_mqstat) {
1208                 audit_mq_getsetattr(mqdes, &mqstat);
1209                 spin_lock(&filp->f_lock);
1210                 if (mqstat.mq_flags & O_NONBLOCK)
1211                         filp->f_flags |= O_NONBLOCK;
1212                 else
1213                         filp->f_flags &= ~O_NONBLOCK;
1214                 spin_unlock(&filp->f_lock);
1215
1216                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1217         }
1218
1219         spin_unlock(&info->lock);
1220
1221         ret = 0;
1222         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1223                                                 sizeof(struct mq_attr)))
1224                 ret = -EFAULT;
1225
1226 out_fput:
1227         fput(filp);
1228 out:
1229         return ret;
1230 }
1231
1232 static const struct inode_operations mqueue_dir_inode_operations = {
1233         .lookup = simple_lookup,
1234         .create = mqueue_create,
1235         .unlink = mqueue_unlink,
1236 };
1237
1238 static const struct file_operations mqueue_file_operations = {
1239         .flush = mqueue_flush_file,
1240         .poll = mqueue_poll_file,
1241         .read = mqueue_read_file,
1242         .llseek = default_llseek,
1243 };
1244
1245 static const struct super_operations mqueue_super_ops = {
1246         .alloc_inode = mqueue_alloc_inode,
1247         .destroy_inode = mqueue_destroy_inode,
1248         .evict_inode = mqueue_evict_inode,
1249         .statfs = simple_statfs,
1250 };
1251
1252 static struct file_system_type mqueue_fs_type = {
1253         .name = "mqueue",
1254         .mount = mqueue_mount,
1255         .kill_sb = kill_litter_super,
1256 };
1257
1258 int mq_init_ns(struct ipc_namespace *ns)
1259 {
1260         ns->mq_queues_count  = 0;
1261         ns->mq_queues_max    = DFLT_QUEUESMAX;
1262         ns->mq_msg_max       = DFLT_MSGMAX;
1263         ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1264
1265         ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1266         if (IS_ERR(ns->mq_mnt)) {
1267                 int err = PTR_ERR(ns->mq_mnt);
1268                 ns->mq_mnt = NULL;
1269                 return err;
1270         }
1271         return 0;
1272 }
1273
1274 void mq_clear_sbinfo(struct ipc_namespace *ns)
1275 {
1276         ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1277 }
1278
1279 void mq_put_mnt(struct ipc_namespace *ns)
1280 {
1281         mntput(ns->mq_mnt);
1282 }
1283
1284 static int __init init_mqueue_fs(void)
1285 {
1286         int error;
1287
1288         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1289                                 sizeof(struct mqueue_inode_info), 0,
1290                                 SLAB_HWCACHE_ALIGN, init_once);
1291         if (mqueue_inode_cachep == NULL)
1292                 return -ENOMEM;
1293
1294         /* ignore failures - they are not fatal */
1295         mq_sysctl_table = mq_register_sysctl_table();
1296
1297         error = register_filesystem(&mqueue_fs_type);
1298         if (error)
1299                 goto out_sysctl;
1300
1301         spin_lock_init(&mq_lock);
1302
1303         init_ipc_ns.mq_mnt = kern_mount_data(&mqueue_fs_type, &init_ipc_ns);
1304         if (IS_ERR(init_ipc_ns.mq_mnt)) {
1305                 error = PTR_ERR(init_ipc_ns.mq_mnt);
1306                 goto out_filesystem;
1307         }
1308
1309         return 0;
1310
1311 out_filesystem:
1312         unregister_filesystem(&mqueue_fs_type);
1313 out_sysctl:
1314         if (mq_sysctl_table)
1315                 unregister_sysctl_table(mq_sysctl_table);
1316         kmem_cache_destroy(mqueue_inode_cachep);
1317         return error;
1318 }
1319
1320 __initcall(init_mqueue_fs);