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                                 kfree(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         make_bad_inode(inode);
 180         iput(inode);
 181         return NULL;
 182 }
 183
 184 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
 185 {
 186         struct inode *inode;
 187         struct ipc_namespace *ns = data;
 188         int error;
 189
 190         sb->s_blocksize = PAGE_CACHE_SIZE;
 191         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 192         sb->s_magic = MQUEUE_MAGIC;
 193         sb->s_op = &mqueue_super_ops;
 194
 195         inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO,
 196                                 NULL);
 197         if (!inode) {
 198                 error = -ENOMEM;
 199                 goto out;
 200         }
 201
 202         sb->s_root = d_alloc_root(inode);
 203         if (!sb->s_root) {
 204                 iput(inode);
 205                 error = -ENOMEM;
 206                 goto out;
 207         }
 208         error = 0;
 209
 210 out:
 211         return error;
 212 }
 213
 214 static int mqueue_get_sb(struct file_system_type *fs_type,
 215                          int flags, const char *dev_name,
 216                          void *data, struct vfsmount *mnt)
 217 {
 218         if (!(flags & MS_KERNMOUNT))
 219                 data = current->nsproxy->ipc_ns;
 220         return get_sb_ns(fs_type, flags, data, mqueue_fill_super, mnt);
 221 }
 222
 223 static void init_once(void *foo)
 224 {
 225         struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
 226
 227         inode_init_once(&p->vfs_inode);
 228 }
 229
 230 static struct inode *mqueue_alloc_inode(struct super_block *sb)
 231 {
 232         struct mqueue_inode_info *ei;
 233
 234         ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
 235         if (!ei)
 236                 return NULL;
 237         return &ei->vfs_inode;
 238 }
 239
 240 static void mqueue_destroy_inode(struct inode *inode)
 241 {
 242         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
 243 }
 244
 245 static void mqueue_delete_inode(struct inode *inode)
 246 {
 247         struct mqueue_inode_info *info;
 248         struct user_struct *user;
 249         unsigned long mq_bytes;
 250         int i;
 251         struct ipc_namespace *ipc_ns;
 252
 253         if (S_ISDIR(inode->i_mode)) {
 254                 clear_inode(inode);
 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         clear_inode(inode);
 266
 267         /* Total amount of bytes accounted for the mqueue */
 268         mq_bytes = info->attr.mq_maxmsg * (sizeof(struct msg_msg *)
 269             + info->attr.mq_msgsize);
 270         user = info->user;
 271         if (user) {
 272                 spin_lock(&mq_lock);
 273                 user->mq_bytes -= mq_bytes;
 274                 /*
 275                  * get_ns_from_inode() ensures that the
 276                  * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
 277                  * to which we now hold a reference, or it is NULL.
 278                  * We can't put it here under mq_lock, though.
 279                  */
 280                 if (ipc_ns)
 281                         ipc_ns->mq_queues_count--;
 282                 spin_unlock(&mq_lock);
 283                 free_uid(user);
 284         }
 285         if (ipc_ns)
 286                 put_ipc_ns(ipc_ns);
 287 }
 288
 289 static int mqueue_create(struct inode *dir, struct dentry *dentry,
 290                                 int mode, struct nameidata *nd)
 291 {
 292         struct inode *inode;
 293         struct mq_attr *attr = dentry->d_fsdata;
 294         int error;
 295         struct ipc_namespace *ipc_ns;
 296
 297         spin_lock(&mq_lock);
 298         ipc_ns = __get_ns_from_inode(dir);
 299         if (!ipc_ns) {
 300                 error = -EACCES;
 301                 goto out_unlock;
 302         }
 303         if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
 304                         !capable(CAP_SYS_RESOURCE)) {
 305                 error = -ENOSPC;
 306                 goto out_unlock;
 307         }
 308         ipc_ns->mq_queues_count++;
 309         spin_unlock(&mq_lock);
 310
 311         inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
 312         if (!inode) {
 313                 error = -ENOMEM;
 314                 spin_lock(&mq_lock);
 315                 ipc_ns->mq_queues_count--;
 316                 goto out_unlock;
 317         }
 318
 319         put_ipc_ns(ipc_ns);
 320         dir->i_size += DIRENT_SIZE;
 321         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 322
 323         d_instantiate(dentry, inode);
 324         dget(dentry);
 325         return 0;
 326 out_unlock:
 327         spin_unlock(&mq_lock);
 328         if (ipc_ns)
 329                 put_ipc_ns(ipc_ns);
 330         return error;
 331 }
 332
 333 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
 334 {
 335         struct inode *inode = dentry->d_inode;
 336
 337         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 338         dir->i_size -= DIRENT_SIZE;
 339         drop_nlink(inode);
 340         dput(dentry);
 341         return 0;
 342 }
 343
 344 /*
 345 *       This is routine for system read from queue file.
 346 *       To avoid mess with doing here some sort of mq_receive we allow
 347 *       to read only queue size & notification info (the only values
 348 *       that are interesting from user point of view and aren't accessible
 349 *       through std routines)
 350 */
 351 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
 352                                 size_t count, loff_t *off)
 353 {
 354         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 355         char buffer[FILENT_SIZE];
 356         ssize_t ret;
 357
 358         spin_lock(&info->lock);
 359         snprintf(buffer, sizeof(buffer),
 360                         "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
 361                         info->qsize,
 362                         info->notify_owner ? info->notify.sigev_notify : 0,
 363                         (info->notify_owner &&
 364                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
 365                                 info->notify.sigev_signo : 0,
 366                         pid_vnr(info->notify_owner));
 367         spin_unlock(&info->lock);
 368         buffer[sizeof(buffer)-1] = '\0';
 369
 370         ret = simple_read_from_buffer(u_data, count, off, buffer,
 371                                 strlen(buffer));
 372         if (ret <= 0)
 373                 return ret;
 374
 375         filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
 376         return ret;
 377 }
 378
 379 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
 380 {
 381         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 382
 383         spin_lock(&info->lock);
 384         if (task_tgid(current) == info->notify_owner)
 385                 remove_notification(info);
 386
 387         spin_unlock(&info->lock);
 388         return 0;
 389 }
 390
 391 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
 392 {
 393         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 394         int retval = 0;
 395
 396         poll_wait(filp, &info->wait_q, poll_tab);
 397
 398         spin_lock(&info->lock);
 399         if (info->attr.mq_curmsgs)
 400                 retval = POLLIN | POLLRDNORM;
 401
 402         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
 403                 retval |= POLLOUT | POLLWRNORM;
 404         spin_unlock(&info->lock);
 405
 406         return retval;
 407 }
 408
 409 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
 410 static void wq_add(struct mqueue_inode_info *info, int sr,
 411                         struct ext_wait_queue *ewp)
 412 {
 413         struct ext_wait_queue *walk;
 414
 415         ewp->task = current;
 416
 417         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
 418                 if (walk->task->static_prio <= current->static_prio) {
 419                         list_add_tail(&ewp->list, &walk->list);
 420                         return;
 421                 }
 422         }
 423         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
 424 }
 425
 426 /*
 427  * Puts current task to sleep. Caller must hold queue lock. After return
 428  * lock isn't held.
 429  * sr: SEND or RECV
 430  */
 431 static int wq_sleep(struct mqueue_inode_info *info, int sr,
 432                         long timeout, struct ext_wait_queue *ewp)
 433 {
 434         int retval;
 435         signed long time;
 436
 437         wq_add(info, sr, ewp);
 438
 439         for (;;) {
 440                 set_current_state(TASK_INTERRUPTIBLE);
 441
 442                 spin_unlock(&info->lock);
 443                 time = schedule_timeout(timeout);
 444
 445                 while (ewp->state == STATE_PENDING)
 446                         cpu_relax();
 447
 448                 if (ewp->state == STATE_READY) {
 449                         retval = 0;
 450                         goto out;
 451                 }
 452                 spin_lock(&info->lock);
 453                 if (ewp->state == STATE_READY) {
 454                         retval = 0;
 455                         goto out_unlock;
 456                 }
 457                 if (signal_pending(current)) {
 458                         retval = -ERESTARTSYS;
 459                         break;
 460                 }
 461                 if (time == 0) {
 462                         retval = -ETIMEDOUT;
 463                         break;
 464                 }
 465         }
 466         list_del(&ewp->list);
 467 out_unlock:
 468         spin_unlock(&info->lock);
 469 out:
 470         return retval;
 471 }
 472
 473 /*
 474  * Returns waiting task that should be serviced first or NULL if none exists
 475  */
 476 static struct ext_wait_queue *wq_get_first_waiter(
 477                 struct mqueue_inode_info *info, int sr)
 478 {
 479         struct list_head *ptr;
 480
 481         ptr = info->e_wait_q[sr].list.prev;
 482         if (ptr == &info->e_wait_q[sr].list)
 483                 return NULL;
 484         return list_entry(ptr, struct ext_wait_queue, list);
 485 }
 486
 487 /* Auxiliary functions to manipulate messages' list */
 488 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
 489 {
 490         int k;
 491
 492         k = info->attr.mq_curmsgs - 1;
 493         while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
 494                 info->messages[k + 1] = info->messages[k];
 495                 k--;
 496         }
 497         info->attr.mq_curmsgs++;
 498         info->qsize += ptr->m_ts;
 499         info->messages[k + 1] = ptr;
 500 }
 501
 502 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
 503 {
 504         info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
 505         return info->messages[info->attr.mq_curmsgs];
 506 }
 507
 508 static inline void set_cookie(struct sk_buff *skb, char code)
 509 {
 510         ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
 511 }
 512
 513 /*
 514  * The next function is only to split too long sys_mq_timedsend
 515  */
 516 static void __do_notify(struct mqueue_inode_info *info)
 517 {
 518         /* notification
 519          * invoked when there is registered process and there isn't process
 520          * waiting synchronously for message AND state of queue changed from
 521          * empty to not empty. Here we are sure that no one is waiting
 522          * synchronously. */
 523         if (info->notify_owner &&
 524             info->attr.mq_curmsgs == 1) {
 525                 struct siginfo sig_i;
 526                 switch (info->notify.sigev_notify) {
 527                 case SIGEV_NONE:
 528                         break;
 529                 case SIGEV_SIGNAL:
 530                         /* sends signal */
 531
 532                         sig_i.si_signo = info->notify.sigev_signo;
 533                         sig_i.si_errno = 0;
 534                         sig_i.si_code = SI_MESGQ;
 535                         sig_i.si_value = info->notify.sigev_value;
 536                         sig_i.si_pid = task_tgid_nr_ns(current,
 537                                                 ns_of_pid(info->notify_owner));
 538                         sig_i.si_uid = current_uid();
 539
 540                         kill_pid_info(info->notify.sigev_signo,
 541                                       &sig_i, info->notify_owner);
 542                         break;
 543                 case SIGEV_THREAD:
 544                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
 545                         netlink_sendskb(info->notify_sock, info->notify_cookie);
 546                         break;
 547                 }
 548                 /* after notification unregisters process */
 549                 put_pid(info->notify_owner);
 550                 info->notify_owner = NULL;
 551         }
 552         wake_up(&info->wait_q);
 553 }
 554
 555 static long prepare_timeout(struct timespec *p)
 556 {
 557         struct timespec nowts;
 558         long timeout;
 559
 560         if (p) {
 561                 if (unlikely(p->tv_nsec < 0 || p->tv_sec < 0
 562                         || p->tv_nsec >= NSEC_PER_SEC))
 563                         return -EINVAL;
 564                 nowts = CURRENT_TIME;
 565                 /* first subtract as jiffies can't be too big */
 566                 p->tv_sec -= nowts.tv_sec;
 567                 if (p->tv_nsec < nowts.tv_nsec) {
 568                         p->tv_nsec += NSEC_PER_SEC;
 569                         p->tv_sec--;
 570                 }
 571                 p->tv_nsec -= nowts.tv_nsec;
 572                 if (p->tv_sec < 0)
 573                         return 0;
 574
 575                 timeout = timespec_to_jiffies(p) + 1;
 576         } else
 577                 return MAX_SCHEDULE_TIMEOUT;
 578
 579         return timeout;
 580 }
 581
 582 static void remove_notification(struct mqueue_inode_info *info)
 583 {
 584         if (info->notify_owner != NULL &&
 585             info->notify.sigev_notify == SIGEV_THREAD) {
 586                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
 587                 netlink_sendskb(info->notify_sock, info->notify_cookie);
 588         }
 589         put_pid(info->notify_owner);
 590         info->notify_owner = NULL;
 591 }
 592
 593 static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
 594 {
 595         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
 596                 return 0;
 597         if (capable(CAP_SYS_RESOURCE)) {
 598                 if (attr->mq_maxmsg > HARD_MSGMAX)
 599                         return 0;
 600         } else {
 601                 if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
 602                                 attr->mq_msgsize > ipc_ns->mq_msgsize_max)
 603                         return 0;
 604         }
 605         /* check for overflow */
 606         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
 607                 return 0;
 608         if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize
 609             + sizeof (struct msg_msg *))) <
 610             (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
 611                 return 0;
 612         return 1;
 613 }
 614
 615 /*
 616  * Invoked when creating a new queue via sys_mq_open
 617  */
 618 static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir,
 619                         struct dentry *dentry, int oflag, mode_t mode,
 620                         struct mq_attr *attr)
 621 {
 622         const struct cred *cred = current_cred();
 623         struct file *result;
 624         int ret;
 625
 626         if (attr) {
 627                 if (!mq_attr_ok(ipc_ns, attr)) {
 628                         ret = -EINVAL;
 629                         goto out;
 630                 }
 631                 /* store for use during create */
 632                 dentry->d_fsdata = attr;
 633         }
 634
 635         mode &= ~current_umask();
 636         ret = mnt_want_write(ipc_ns->mq_mnt);
 637         if (ret)
 638                 goto out;
 639         ret = vfs_create(dir->d_inode, dentry, mode, NULL);
 640         dentry->d_fsdata = NULL;
 641         if (ret)
 642                 goto out_drop_write;
 643
 644         result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
 645         /*
 646          * dentry_open() took a persistent mnt_want_write(),
 647          * so we can now drop this one.
 648          */
 649         mnt_drop_write(ipc_ns->mq_mnt);
 650         return result;
 651
 652 out_drop_write:
 653         mnt_drop_write(ipc_ns->mq_mnt);
 654 out:
 655         dput(dentry);
 656         mntput(ipc_ns->mq_mnt);
 657         return ERR_PTR(ret);
 658 }
 659
 660 /* Opens existing queue */
 661 static struct file *do_open(struct ipc_namespace *ipc_ns,
 662                                 struct dentry *dentry, int oflag)
 663 {
 664         int ret;
 665         const struct cred *cred = current_cred();
 666
 667         static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
 668                                                   MAY_READ | MAY_WRITE };
 669
 670         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
 671                 ret = -EINVAL;
 672                 goto err;
 673         }
 674
 675         if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
 676                 ret = -EACCES;
 677                 goto err;
 678         }
 679
 680         return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
 681
 682 err:
 683         dput(dentry);
 684         mntput(ipc_ns->mq_mnt);
 685         return ERR_PTR(ret);
 686 }
 687
 688 SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, mode_t, mode,
 689                 struct mq_attr __user *, u_attr)
 690 {
 691         struct dentry *dentry;
 692         struct file *filp;
 693         char *name;
 694         struct mq_attr attr;
 695         int fd, error;
 696         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
 697
 698         if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
 699                 return -EFAULT;
 700
 701         audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
 702
 703         if (IS_ERR(name = getname(u_name)))
 704                 return PTR_ERR(name);
 705
 706         fd = get_unused_fd_flags(O_CLOEXEC);
 707         if (fd < 0)
 708                 goto out_putname;
 709
 710         mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 711         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
 712         if (IS_ERR(dentry)) {
 713                 error = PTR_ERR(dentry);
 714                 goto out_putfd;
 715         }
 716         mntget(ipc_ns->mq_mnt);
 717
 718         if (oflag & O_CREAT) {
 719                 if (dentry->d_inode) {  /* entry already exists */
 720                         audit_inode(name, dentry);
 721                         if (oflag & O_EXCL) {
 722                                 error = -EEXIST;
 723                                 goto out;
 724                         }
 725                         filp = do_open(ipc_ns, dentry, oflag);
 726                 } else {
 727                         filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root,
 728                                                 dentry, oflag, mode,
 729                                                 u_attr ? &attr : NULL);
 730                 }
 731         } else {
 732                 if (!dentry->d_inode) {
 733                         error = -ENOENT;
 734                         goto out;
 735                 }
 736                 audit_inode(name, dentry);
 737                 filp = do_open(ipc_ns, dentry, oflag);
 738         }
 739
 740         if (IS_ERR(filp)) {
 741                 error = PTR_ERR(filp);
 742                 goto out_putfd;
 743         }
 744
 745         fd_install(fd, filp);
 746         goto out_upsem;
 747
 748 out:
 749         dput(dentry);
 750         mntput(ipc_ns->mq_mnt);
 751 out_putfd:
 752         put_unused_fd(fd);
 753         fd = error;
 754 out_upsem:
 755         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 756 out_putname:
 757         putname(name);
 758         return fd;
 759 }
 760
 761 SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
 762 {
 763         int err;
 764         char *name;
 765         struct dentry *dentry;
 766         struct inode *inode = NULL;
 767         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
 768
 769         name = getname(u_name);
 770         if (IS_ERR(name))
 771                 return PTR_ERR(name);
 772
 773         mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
 774                         I_MUTEX_PARENT);
 775         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
 776         if (IS_ERR(dentry)) {
 777                 err = PTR_ERR(dentry);
 778                 goto out_unlock;
 779         }
 780
 781         if (!dentry->d_inode) {
 782                 err = -ENOENT;
 783                 goto out_err;
 784         }
 785
 786         inode = dentry->d_inode;
 787         if (inode)
 788                 atomic_inc(&inode->i_count);
 789         err = mnt_want_write(ipc_ns->mq_mnt);
 790         if (err)
 791                 goto out_err;
 792         err = vfs_unlink(dentry->d_parent->d_inode, dentry);
 793         mnt_drop_write(ipc_ns->mq_mnt);
 794 out_err:
 795         dput(dentry);
 796
 797 out_unlock:
 798         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 799         putname(name);
 800         if (inode)
 801                 iput(inode);
 802
 803         return err;
 804 }
 805
 806 /* Pipelined send and receive functions.
 807  *
 808  * If a receiver finds no waiting message, then it registers itself in the
 809  * list of waiting receivers. A sender checks that list before adding the new
 810  * message into the message array. If there is a waiting receiver, then it
 811  * bypasses the message array and directly hands the message over to the
 812  * receiver.
 813  * The receiver accepts the message and returns without grabbing the queue
 814  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
 815  * are necessary. The same algorithm is used for sysv semaphores, see
 816  * ipc/sem.c for more details.
 817  *
 818  * The same algorithm is used for senders.
 819  */
 820
 821 /* pipelined_send() - send a message directly to the task waiting in
 822  * sys_mq_timedreceive() (without inserting message into a queue).
 823  */
 824 static inline void pipelined_send(struct mqueue_inode_info *info,
 825                                   struct msg_msg *message,
 826                                   struct ext_wait_queue *receiver)
 827 {
 828         receiver->msg = message;
 829         list_del(&receiver->list);
 830         receiver->state = STATE_PENDING;
 831         wake_up_process(receiver->task);
 832         smp_wmb();
 833         receiver->state = STATE_READY;
 834 }
 835
 836 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
 837  * gets its message and put to the queue (we have one free place for sure). */
 838 static inline void pipelined_receive(struct mqueue_inode_info *info)
 839 {
 840         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
 841
 842         if (!sender) {
 843                 /* for poll */
 844                 wake_up_interruptible(&info->wait_q);
 845                 return;
 846         }
 847         msg_insert(sender->msg, info);
 848         list_del(&sender->list);
 849         sender->state = STATE_PENDING;
 850         wake_up_process(sender->task);
 851         smp_wmb();
 852         sender->state = STATE_READY;
 853 }
 854
 855 SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
 856                 size_t, msg_len, unsigned int, msg_prio,
 857                 const struct timespec __user *, u_abs_timeout)
 858 {
 859         struct file *filp;
 860         struct inode *inode;
 861         struct ext_wait_queue wait;
 862         struct ext_wait_queue *receiver;
 863         struct msg_msg *msg_ptr;
 864         struct mqueue_inode_info *info;
 865         struct timespec ts, *p = NULL;
 866         long timeout;
 867         int ret;
 868
 869         if (u_abs_timeout) {
 870                 if (copy_from_user(&ts, u_abs_timeout,
 871                                         sizeof(struct timespec)))
 872                         return -EFAULT;
 873                 p = &ts;
 874         }
 875
 876         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
 877                 return -EINVAL;
 878
 879         audit_mq_sendrecv(mqdes, msg_len, msg_prio, p);
 880         timeout = prepare_timeout(p);
 881
 882         filp = fget(mqdes);
 883         if (unlikely(!filp)) {
 884                 ret = -EBADF;
 885                 goto out;
 886         }
 887
 888         inode = filp->f_path.dentry->d_inode;
 889         if (unlikely(filp->f_op != &mqueue_file_operations)) {
 890                 ret = -EBADF;
 891                 goto out_fput;
 892         }
 893         info = MQUEUE_I(inode);
 894         audit_inode(NULL, filp->f_path.dentry);
 895
 896         if (unlikely(!(filp->f_mode & FMODE_WRITE))) {
 897                 ret = -EBADF;
 898                 goto out_fput;
 899         }
 900
 901         if (unlikely(msg_len > info->attr.mq_msgsize)) {
 902                 ret = -EMSGSIZE;
 903                 goto out_fput;
 904         }
 905
 906         /* First try to allocate memory, before doing anything with
 907          * existing queues. */
 908         msg_ptr = load_msg(u_msg_ptr, msg_len);
 909         if (IS_ERR(msg_ptr)) {
 910                 ret = PTR_ERR(msg_ptr);
 911                 goto out_fput;
 912         }
 913         msg_ptr->m_ts = msg_len;
 914         msg_ptr->m_type = msg_prio;
 915
 916         spin_lock(&info->lock);
 917
 918         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
 919                 if (filp->f_flags & O_NONBLOCK) {
 920                         spin_unlock(&info->lock);
 921                         ret = -EAGAIN;
 922                 } else if (unlikely(timeout < 0)) {
 923                         spin_unlock(&info->lock);
 924                         ret = timeout;
 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         long timeout;
 958         ssize_t ret;
 959         struct msg_msg *msg_ptr;
 960         struct file *filp;
 961         struct inode *inode;
 962         struct mqueue_inode_info *info;
 963         struct ext_wait_queue wait;
 964         struct timespec ts, *p = NULL;
 965
 966         if (u_abs_timeout) {
 967                 if (copy_from_user(&ts, u_abs_timeout,
 968                                         sizeof(struct timespec)))
 969                         return -EFAULT;
 970                 p = &ts;
 971         }
 972
 973         audit_mq_sendrecv(mqdes, msg_len, 0, p);
 974         timeout = prepare_timeout(p);
 975
 976         filp = fget(mqdes);
 977         if (unlikely(!filp)) {
 978                 ret = -EBADF;
 979                 goto out;
 980         }
 981
 982         inode = filp->f_path.dentry->d_inode;
 983         if (unlikely(filp->f_op != &mqueue_file_operations)) {
 984                 ret = -EBADF;
 985                 goto out_fput;
 986         }
 987         info = MQUEUE_I(inode);
 988         audit_inode(NULL, filp->f_path.dentry);
 989
 990         if (unlikely(!(filp->f_mode & FMODE_READ))) {
 991                 ret = -EBADF;
 992                 goto out_fput;
 993         }
 994
 995         /* checks if buffer is big enough */
 996         if (unlikely(msg_len < info->attr.mq_msgsize)) {
 997                 ret = -EMSGSIZE;
 998                 goto out_fput;
 999         }
1000
1001         spin_lock(&info->lock);
1002         if (info->attr.mq_curmsgs == 0) {
1003                 if (filp->f_flags & O_NONBLOCK) {
1004                         spin_unlock(&info->lock);
1005                         ret = -EAGAIN;
1006                         msg_ptr = NULL;
1007                 } else if (unlikely(timeout < 0)) {
1008                         spin_unlock(&info->lock);
1009                         ret = timeout;
1010                         msg_ptr = NULL;
1011                 } else {
1012                         wait.task = current;
1013                         wait.state = STATE_NONE;
1014                         ret = wq_sleep(info, RECV, timeout, &wait);
1015                         msg_ptr = wait.msg;
1016                 }
1017         } else {
1018                 msg_ptr = msg_get(info);
1019
1020                 inode->i_atime = inode->i_mtime = inode->i_ctime =
1021                                 CURRENT_TIME;
1022
1023                 /* There is now free space in queue. */
1024                 pipelined_receive(info);
1025                 spin_unlock(&info->lock);
1026                 ret = 0;
1027         }
1028         if (ret == 0) {
1029                 ret = msg_ptr->m_ts;
1030
1031                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1032                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1033                         ret = -EFAULT;
1034                 }
1035                 free_msg(msg_ptr);
1036         }
1037 out_fput:
1038         fput(filp);
1039 out:
1040         return ret;
1041 }
1042
1043 /*
1044  * Notes: the case when user wants us to deregister (with NULL as pointer)
1045  * and he isn't currently owner of notification, will be silently discarded.
1046  * It isn't explicitly defined in the POSIX.
1047  */
1048 SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1049                 const struct sigevent __user *, u_notification)
1050 {
1051         int ret;
1052         struct file *filp;
1053         struct sock *sock;
1054         struct inode *inode;
1055         struct sigevent notification;
1056         struct mqueue_inode_info *info;
1057         struct sk_buff *nc;
1058
1059         if (u_notification) {
1060                 if (copy_from_user(&notification, u_notification,
1061                                         sizeof(struct sigevent)))
1062                         return -EFAULT;
1063         }
1064
1065         audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1066
1067         nc = NULL;
1068         sock = NULL;
1069         if (u_notification != NULL) {
1070                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1071                              notification.sigev_notify != SIGEV_SIGNAL &&
1072                              notification.sigev_notify != SIGEV_THREAD))
1073                         return -EINVAL;
1074                 if (notification.sigev_notify == SIGEV_SIGNAL &&
1075                         !valid_signal(notification.sigev_signo)) {
1076                         return -EINVAL;
1077                 }
1078                 if (notification.sigev_notify == SIGEV_THREAD) {
1079                         long timeo;
1080
1081                         /* create the notify skb */
1082                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1083                         if (!nc) {
1084                                 ret = -ENOMEM;
1085                                 goto out;
1086                         }
1087                         if (copy_from_user(nc->data,
1088                                         notification.sigev_value.sival_ptr,
1089                                         NOTIFY_COOKIE_LEN)) {
1090                                 ret = -EFAULT;
1091                                 goto out;
1092                         }
1093
1094                         /* TODO: add a header? */
1095                         skb_put(nc, NOTIFY_COOKIE_LEN);
1096                         /* and attach it to the socket */
1097 retry:
1098                         filp = fget(notification.sigev_signo);
1099                         if (!filp) {
1100                                 ret = -EBADF;
1101                                 goto out;
1102                         }
1103                         sock = netlink_getsockbyfilp(filp);
1104                         fput(filp);
1105                         if (IS_ERR(sock)) {
1106                                 ret = PTR_ERR(sock);
1107                                 sock = NULL;
1108                                 goto out;
1109                         }
1110
1111                         timeo = MAX_SCHEDULE_TIMEOUT;
1112                         ret = netlink_attachskb(sock, nc, &timeo, NULL);
1113                         if (ret == 1)
1114                                 goto retry;
1115                         if (ret) {
1116                                 sock = NULL;
1117                                 nc = NULL;
1118                                 goto out;
1119                         }
1120                 }
1121         }
1122
1123         filp = fget(mqdes);
1124         if (!filp) {
1125                 ret = -EBADF;
1126                 goto out;
1127         }
1128
1129         inode = filp->f_path.dentry->d_inode;
1130         if (unlikely(filp->f_op != &mqueue_file_operations)) {
1131                 ret = -EBADF;
1132                 goto out_fput;
1133         }
1134         info = MQUEUE_I(inode);
1135
1136         ret = 0;
1137         spin_lock(&info->lock);
1138         if (u_notification == NULL) {
1139                 if (info->notify_owner == task_tgid(current)) {
1140                         remove_notification(info);
1141                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1142                 }
1143         } else if (info->notify_owner != NULL) {
1144                 ret = -EBUSY;
1145         } else {
1146                 switch (notification.sigev_notify) {
1147                 case SIGEV_NONE:
1148                         info->notify.sigev_notify = SIGEV_NONE;
1149                         break;
1150                 case SIGEV_THREAD:
1151                         info->notify_sock = sock;
1152                         info->notify_cookie = nc;
1153                         sock = NULL;
1154                         nc = NULL;
1155                         info->notify.sigev_notify = SIGEV_THREAD;
1156                         break;
1157                 case SIGEV_SIGNAL:
1158                         info->notify.sigev_signo = notification.sigev_signo;
1159                         info->notify.sigev_value = notification.sigev_value;
1160                         info->notify.sigev_notify = SIGEV_SIGNAL;
1161                         break;
1162                 }
1163
1164                 info->notify_owner = get_pid(task_tgid(current));
1165                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1166         }
1167         spin_unlock(&info->lock);
1168 out_fput:
1169         fput(filp);
1170 out:
1171         if (sock) {
1172                 netlink_detachskb(sock, nc);
1173         } else if (nc) {
1174                 dev_kfree_skb(nc);
1175         }
1176         return ret;
1177 }
1178
1179 SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1180                 const struct mq_attr __user *, u_mqstat,
1181                 struct mq_attr __user *, u_omqstat)
1182 {
1183         int ret;
1184         struct mq_attr mqstat, omqstat;
1185         struct file *filp;
1186         struct inode *inode;
1187         struct mqueue_inode_info *info;
1188
1189         if (u_mqstat != NULL) {
1190                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1191                         return -EFAULT;
1192                 if (mqstat.mq_flags & (~O_NONBLOCK))
1193                         return -EINVAL;
1194         }
1195
1196         filp = fget(mqdes);
1197         if (!filp) {
1198                 ret = -EBADF;
1199                 goto out;
1200         }
1201
1202         inode = filp->f_path.dentry->d_inode;
1203         if (unlikely(filp->f_op != &mqueue_file_operations)) {
1204                 ret = -EBADF;
1205                 goto out_fput;
1206         }
1207         info = MQUEUE_I(inode);
1208
1209         spin_lock(&info->lock);
1210
1211         omqstat = info->attr;
1212         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1213         if (u_mqstat) {
1214                 audit_mq_getsetattr(mqdes, &mqstat);
1215                 spin_lock(&filp->f_lock);
1216                 if (mqstat.mq_flags & O_NONBLOCK)
1217                         filp->f_flags |= O_NONBLOCK;
1218                 else
1219                         filp->f_flags &= ~O_NONBLOCK;
1220                 spin_unlock(&filp->f_lock);
1221
1222                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1223         }
1224
1225         spin_unlock(&info->lock);
1226
1227         ret = 0;
1228         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1229                                                 sizeof(struct mq_attr)))
1230                 ret = -EFAULT;
1231
1232 out_fput:
1233         fput(filp);
1234 out:
1235         return ret;
1236 }
1237
1238 static const struct inode_operations mqueue_dir_inode_operations = {
1239         .lookup = simple_lookup,
1240         .create = mqueue_create,
1241         .unlink = mqueue_unlink,
1242 };
1243
1244 static const struct file_operations mqueue_file_operations = {
1245         .flush = mqueue_flush_file,
1246         .poll = mqueue_poll_file,
1247         .read = mqueue_read_file,
1248 };
1249
1250 static const struct super_operations mqueue_super_ops = {
1251         .alloc_inode = mqueue_alloc_inode,
1252         .destroy_inode = mqueue_destroy_inode,
1253         .statfs = simple_statfs,
1254         .delete_inode = mqueue_delete_inode,
1255         .drop_inode = generic_delete_inode,
1256 };
1257
1258 static struct file_system_type mqueue_fs_type = {
1259         .name = "mqueue",
1260         .get_sb = mqueue_get_sb,
1261         .kill_sb = kill_litter_super,
1262 };
1263
1264 int mq_init_ns(struct ipc_namespace *ns)
1265 {
1266         ns->mq_queues_count  = 0;
1267         ns->mq_queues_max    = DFLT_QUEUESMAX;
1268         ns->mq_msg_max       = DFLT_MSGMAX;
1269         ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1270
1271         ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1272         if (IS_ERR(ns->mq_mnt)) {
1273                 int err = PTR_ERR(ns->mq_mnt);
1274                 ns->mq_mnt = NULL;
1275                 return err;
1276         }
1277         return 0;
1278 }
1279
1280 void mq_clear_sbinfo(struct ipc_namespace *ns)
1281 {
1282         ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1283 }
1284
1285 void mq_put_mnt(struct ipc_namespace *ns)
1286 {
1287         mntput(ns->mq_mnt);
1288 }
1289
1290 static int __init init_mqueue_fs(void)
1291 {
1292         int error;
1293
1294         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1295                                 sizeof(struct mqueue_inode_info), 0,
1296                                 SLAB_HWCACHE_ALIGN, init_once);
1297         if (mqueue_inode_cachep == NULL)
1298                 return -ENOMEM;
1299
1300         /* ignore failures - they are not fatal */
1301         mq_sysctl_table = mq_register_sysctl_table();
1302
1303         error = register_filesystem(&mqueue_fs_type);
1304         if (error)
1305                 goto out_sysctl;
1306
1307         spin_lock_init(&mq_lock);
1308
1309         init_ipc_ns.mq_mnt = kern_mount_data(&mqueue_fs_type, &init_ipc_ns);
1310         if (IS_ERR(init_ipc_ns.mq_mnt)) {
1311                 error = PTR_ERR(init_ipc_ns.mq_mnt);
1312                 goto out_filesystem;
1313         }
1314
1315         return 0;
1316
1317 out_filesystem:
1318         unregister_filesystem(&mqueue_fs_type);
1319 out_sysctl:
1320         if (mq_sysctl_table)
1321                 unregister_sysctl_table(mq_sysctl_table);
1322         kmem_cache_destroy(mqueue_inode_cachep);
1323         return error;
1324 }
1325
1326 __initcall(init_mqueue_fs);