SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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
  36 #include <net/sock.h>
  37 #include "util.h"
  38
  39 #define MQUEUE_MAGIC    0x19800202
  40 #define DIRENT_SIZE     20
  41 #define FILENT_SIZE     80
  42
  43 #define SEND            0
  44 #define RECV            1
  45
  46 #define STATE_NONE      0
  47 #define STATE_PENDING   1
  48 #define STATE_READY     2
  49
  50 struct ext_wait_queue {         /* queue of sleeping tasks */
  51         struct task_struct *task;
  52         struct list_head list;
  53         struct msg_msg *msg;    /* ptr of loaded message */
  54         int state;              /* one of STATE_* values */
  55 };
  56
  57 struct mqueue_inode_info {
  58         spinlock_t lock;
  59         struct inode vfs_inode;
  60         wait_queue_head_t wait_q;
  61
  62         struct msg_msg **messages;
  63         struct mq_attr attr;
  64
  65         struct sigevent notify;
  66         struct pid* notify_owner;
  67         struct user_struct *user;       /* user who created, for accounting */
  68         struct sock *notify_sock;
  69         struct sk_buff *notify_cookie;
  70
  71         /* for tasks waiting for free space and messages, respectively */
  72         struct ext_wait_queue e_wait_q[2];
  73
  74         unsigned long qsize; /* size of queue in memory (sum of all msgs) */
  75 };
  76
  77 static const struct inode_operations mqueue_dir_inode_operations;
  78 static const struct file_operations mqueue_file_operations;
  79 static const struct super_operations mqueue_super_ops;
  80 static void remove_notification(struct mqueue_inode_info *info);
  81
  82 static struct kmem_cache *mqueue_inode_cachep;
  83
  84 static struct ctl_table_header * mq_sysctl_table;
  85
  86 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
  87 {
  88         return container_of(inode, struct mqueue_inode_info, vfs_inode);
  89 }
  90
  91 /*
  92  * This routine should be called with the mq_lock held.
  93  */
  94 static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
  95 {
  96         return get_ipc_ns(inode->i_sb->s_fs_info);
  97 }
  98
  99 static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
 100 {
 101         struct ipc_namespace *ns;
 102
 103         spin_lock(&mq_lock);
 104         ns = __get_ns_from_inode(inode);
 105         spin_unlock(&mq_lock);
 106         return ns;
 107 }
 108
 109 static struct inode *mqueue_get_inode(struct super_block *sb,
 110                 struct ipc_namespace *ipc_ns, int mode,
 111                 struct mq_attr *attr)
 112 {
 113         struct user_struct *u = current_user();
 114         struct inode *inode;
 115
 116         inode = new_inode(sb);
 117         if (inode) {
 118                 inode->i_mode = mode;
 119                 inode->i_uid = current_fsuid();
 120                 inode->i_gid = current_fsgid();
 121                 inode->i_mtime = inode->i_ctime = inode->i_atime =
 122                                 CURRENT_TIME;
 123
 124                 if (S_ISREG(mode)) {
 125                         struct mqueue_inode_info *info;
 126                         struct task_struct *p = current;
 127                         unsigned long mq_bytes, mq_msg_tblsz;
 128
 129                         inode->i_fop = &mqueue_file_operations;
 130                         inode->i_size = FILENT_SIZE;
 131                         /* mqueue specific info */
 132                         info = MQUEUE_I(inode);
 133                         spin_lock_init(&info->lock);
 134                         init_waitqueue_head(&info->wait_q);
 135                         INIT_LIST_HEAD(&info->e_wait_q[0].list);
 136                         INIT_LIST_HEAD(&info->e_wait_q[1].list);
 137                         info->notify_owner = NULL;
 138                         info->qsize = 0;
 139                         info->user = NULL;      /* set when all is ok */
 140                         memset(&info->attr, 0, sizeof(info->attr));
 141                         info->attr.mq_maxmsg = ipc_ns->mq_msg_max;
 142                         info->attr.mq_msgsize = ipc_ns->mq_msgsize_max;
 143                         if (attr) {
 144                                 info->attr.mq_maxmsg = attr->mq_maxmsg;
 145                                 info->attr.mq_msgsize = attr->mq_msgsize;
 146                         }
 147                         mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
 148                         info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
 149                         if (!info->messages)
 150                                 goto out_inode;
 151
 152                         mq_bytes = (mq_msg_tblsz +
 153                                 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
 154
 155                         spin_lock(&mq_lock);
 156                         if (u->mq_bytes + mq_bytes < u->mq_bytes ||
 157                             u->mq_bytes + mq_bytes >
 158                             p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
 159                                 spin_unlock(&mq_lock);
 160                                 kfree(info->messages);
 161                                 goto out_inode;
 162                         }
 163                         u->mq_bytes += mq_bytes;
 164                         spin_unlock(&mq_lock);
 165
 166                         /* all is ok */
 167                         info->user = get_uid(u);
 168                 } else if (S_ISDIR(mode)) {
 169                         inc_nlink(inode);
 170                         /* Some things misbehave if size == 0 on a directory */
 171                         inode->i_size = 2 * DIRENT_SIZE;
 172                         inode->i_op = &mqueue_dir_inode_operations;
 173                         inode->i_fop = &simple_dir_operations;
 174                 }
 175         }
 176         return inode;
 177 out_inode:
 178         make_bad_inode(inode);
 179         iput(inode);
 180         return NULL;
 181 }
 182
 183 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
 184 {
 185         struct inode *inode;
 186         struct ipc_namespace *ns = data;
 187         int error = 0;
 188
 189         sb->s_blocksize = PAGE_CACHE_SIZE;
 190         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 191         sb->s_magic = MQUEUE_MAGIC;
 192         sb->s_op = &mqueue_super_ops;
 193
 194         inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO,
 195                                 NULL);
 196         if (!inode) {
 197                 error = -ENOMEM;
 198                 goto out;
 199         }
 200
 201         sb->s_root = d_alloc_root(inode);
 202         if (!sb->s_root) {
 203                 iput(inode);
 204                 error = -ENOMEM;
 205         }
 206
 207 out:
 208         return error;
 209 }
 210
 211 static int mqueue_get_sb(struct file_system_type *fs_type,
 212                          int flags, const char *dev_name,
 213                          void *data, struct vfsmount *mnt)
 214 {
 215         if (!(flags & MS_KERNMOUNT))
 216                 data = current->nsproxy->ipc_ns;
 217         return get_sb_ns(fs_type, flags, data, mqueue_fill_super, mnt);
 218 }
 219
 220 static void init_once(void *foo)
 221 {
 222         struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
 223
 224         inode_init_once(&p->vfs_inode);
 225 }
 226
 227 static struct inode *mqueue_alloc_inode(struct super_block *sb)
 228 {
 229         struct mqueue_inode_info *ei;
 230
 231         ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
 232         if (!ei)
 233                 return NULL;
 234         return &ei->vfs_inode;
 235 }
 236
 237 static void mqueue_destroy_inode(struct inode *inode)
 238 {
 239         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
 240 }
 241
 242 static void mqueue_delete_inode(struct inode *inode)
 243 {
 244         struct mqueue_inode_info *info;
 245         struct user_struct *user;
 246         unsigned long mq_bytes;
 247         int i;
 248         struct ipc_namespace *ipc_ns;
 249
 250         if (S_ISDIR(inode->i_mode)) {
 251                 clear_inode(inode);
 252                 return;
 253         }
 254         ipc_ns = get_ns_from_inode(inode);
 255         info = MQUEUE_I(inode);
 256         spin_lock(&info->lock);
 257         for (i = 0; i < info->attr.mq_curmsgs; i++)
 258                 free_msg(info->messages[i]);
 259         kfree(info->messages);
 260         spin_unlock(&info->lock);
 261
 262         clear_inode(inode);
 263
 264         mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
 265                    (info->attr.mq_maxmsg * info->attr.mq_msgsize));
 266         user = info->user;
 267         if (user) {
 268                 spin_lock(&mq_lock);
 269                 user->mq_bytes -= mq_bytes;
 270                 /*
 271                  * get_ns_from_inode() ensures that the
 272                  * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
 273                  * to which we now hold a reference, or it is NULL.
 274                  * We can't put it here under mq_lock, though.
 275                  */
 276                 if (ipc_ns)
 277                         ipc_ns->mq_queues_count--;
 278                 spin_unlock(&mq_lock);
 279                 free_uid(user);
 280         }
 281         if (ipc_ns)
 282                 put_ipc_ns(ipc_ns);
 283 }
 284
 285 static int mqueue_create(struct inode *dir, struct dentry *dentry,
 286                                 int mode, struct nameidata *nd)
 287 {
 288         struct inode *inode;
 289         struct mq_attr *attr = dentry->d_fsdata;
 290         int error;
 291         struct ipc_namespace *ipc_ns;
 292
 293         spin_lock(&mq_lock);
 294         ipc_ns = __get_ns_from_inode(dir);
 295         if (!ipc_ns) {
 296                 error = -EACCES;
 297                 goto out_unlock;
 298         }
 299         if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
 300                         !capable(CAP_SYS_RESOURCE)) {
 301                 error = -ENOSPC;
 302                 goto out_unlock;
 303         }
 304         ipc_ns->mq_queues_count++;
 305         spin_unlock(&mq_lock);
 306
 307         inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
 308         if (!inode) {
 309                 error = -ENOMEM;
 310                 spin_lock(&mq_lock);
 311                 ipc_ns->mq_queues_count--;
 312                 goto out_unlock;
 313         }
 314
 315         put_ipc_ns(ipc_ns);
 316         dir->i_size += DIRENT_SIZE;
 317         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 318
 319         d_instantiate(dentry, inode);
 320         dget(dentry);
 321         return 0;
 322 out_unlock:
 323         spin_unlock(&mq_lock);
 324         if (ipc_ns)
 325                 put_ipc_ns(ipc_ns);
 326         return error;
 327 }
 328
 329 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
 330 {
 331         struct inode *inode = dentry->d_inode;
 332
 333         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 334         dir->i_size -= DIRENT_SIZE;
 335         drop_nlink(inode);
 336         dput(dentry);
 337         return 0;
 338 }
 339
 340 /*
 341 *       This is routine for system read from queue file.
 342 *       To avoid mess with doing here some sort of mq_receive we allow
 343 *       to read only queue size & notification info (the only values
 344 *       that are interesting from user point of view and aren't accessible
 345 *       through std routines)
 346 */
 347 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
 348                                 size_t count, loff_t *off)
 349 {
 350         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 351         char buffer[FILENT_SIZE];
 352         ssize_t ret;
 353
 354         spin_lock(&info->lock);
 355         snprintf(buffer, sizeof(buffer),
 356                         "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
 357                         info->qsize,
 358                         info->notify_owner ? info->notify.sigev_notify : 0,
 359                         (info->notify_owner &&
 360                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
 361                                 info->notify.sigev_signo : 0,
 362                         pid_vnr(info->notify_owner));
 363         spin_unlock(&info->lock);
 364         buffer[sizeof(buffer)-1] = '\0';
 365
 366         ret = simple_read_from_buffer(u_data, count, off, buffer,
 367                                 strlen(buffer));
 368         if (ret <= 0)
 369                 return ret;
 370
 371         filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
 372         return ret;
 373 }
 374
 375 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
 376 {
 377         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 378
 379         spin_lock(&info->lock);
 380         if (task_tgid(current) == info->notify_owner)
 381                 remove_notification(info);
 382
 383         spin_unlock(&info->lock);
 384         return 0;
 385 }
 386
 387 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
 388 {
 389         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 390         int retval = 0;
 391
 392         poll_wait(filp, &info->wait_q, poll_tab);
 393
 394         spin_lock(&info->lock);
 395         if (info->attr.mq_curmsgs)
 396                 retval = POLLIN | POLLRDNORM;
 397
 398         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
 399                 retval |= POLLOUT | POLLWRNORM;
 400         spin_unlock(&info->lock);
 401
 402         return retval;
 403 }
 404
 405 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
 406 static void wq_add(struct mqueue_inode_info *info, int sr,
 407                         struct ext_wait_queue *ewp)
 408 {
 409         struct ext_wait_queue *walk;
 410
 411         ewp->task = current;
 412
 413         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
 414                 if (walk->task->static_prio <= current->static_prio) {
 415                         list_add_tail(&ewp->list, &walk->list);
 416                         return;
 417                 }
 418         }
 419         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
 420 }
 421
 422 /*
 423  * Puts current task to sleep. Caller must hold queue lock. After return
 424  * lock isn't held.
 425  * sr: SEND or RECV
 426  */
 427 static int wq_sleep(struct mqueue_inode_info *info, int sr,
 428                         long timeout, struct ext_wait_queue *ewp)
 429 {
 430         int retval;
 431         signed long time;
 432
 433         wq_add(info, sr, ewp);
 434
 435         for (;;) {
 436                 set_current_state(TASK_INTERRUPTIBLE);
 437
 438                 spin_unlock(&info->lock);
 439                 time = schedule_timeout(timeout);
 440
 441                 while (ewp->state == STATE_PENDING)
 442                         cpu_relax();
 443
 444                 if (ewp->state == STATE_READY) {
 445                         retval = 0;
 446                         goto out;
 447                 }
 448                 spin_lock(&info->lock);
 449                 if (ewp->state == STATE_READY) {
 450                         retval = 0;
 451                         goto out_unlock;
 452                 }
 453                 if (signal_pending(current)) {
 454                         retval = -ERESTARTSYS;
 455                         break;
 456                 }
 457                 if (time == 0) {
 458                         retval = -ETIMEDOUT;
 459                         break;
 460                 }
 461         }
 462         list_del(&ewp->list);
 463 out_unlock:
 464         spin_unlock(&info->lock);
 465 out:
 466         return retval;
 467 }
 468
 469 /*
 470  * Returns waiting task that should be serviced first or NULL if none exists
 471  */
 472 static struct ext_wait_queue *wq_get_first_waiter(
 473                 struct mqueue_inode_info *info, int sr)
 474 {
 475         struct list_head *ptr;
 476
 477         ptr = info->e_wait_q[sr].list.prev;
 478         if (ptr == &info->e_wait_q[sr].list)
 479                 return NULL;
 480         return list_entry(ptr, struct ext_wait_queue, list);
 481 }
 482
 483 /* Auxiliary functions to manipulate messages' list */
 484 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
 485 {
 486         int k;
 487
 488         k = info->attr.mq_curmsgs - 1;
 489         while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
 490                 info->messages[k + 1] = info->messages[k];
 491                 k--;
 492         }
 493         info->attr.mq_curmsgs++;
 494         info->qsize += ptr->m_ts;
 495         info->messages[k + 1] = ptr;
 496 }
 497
 498 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
 499 {
 500         info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
 501         return info->messages[info->attr.mq_curmsgs];
 502 }
 503
 504 static inline void set_cookie(struct sk_buff *skb, char code)
 505 {
 506         ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
 507 }
 508
 509 /*
 510  * The next function is only to split too long sys_mq_timedsend
 511  */
 512 static void __do_notify(struct mqueue_inode_info *info)
 513 {
 514         /* notification
 515          * invoked when there is registered process and there isn't process
 516          * waiting synchronously for message AND state of queue changed from
 517          * empty to not empty. Here we are sure that no one is waiting
 518          * synchronously. */
 519         if (info->notify_owner &&
 520             info->attr.mq_curmsgs == 1) {
 521                 struct siginfo sig_i;
 522                 switch (info->notify.sigev_notify) {
 523                 case SIGEV_NONE:
 524                         break;
 525                 case SIGEV_SIGNAL:
 526                         /* sends signal */
 527
 528                         sig_i.si_signo = info->notify.sigev_signo;
 529                         sig_i.si_errno = 0;
 530                         sig_i.si_code = SI_MESGQ;
 531                         sig_i.si_value = info->notify.sigev_value;
 532                         sig_i.si_pid = task_tgid_nr_ns(current,
 533                                                 ns_of_pid(info->notify_owner));
 534                         sig_i.si_uid = current_uid();
 535
 536                         kill_pid_info(info->notify.sigev_signo,
 537                                       &sig_i, info->notify_owner);
 538                         break;
 539                 case SIGEV_THREAD:
 540                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
 541                         netlink_sendskb(info->notify_sock, info->notify_cookie);
 542                         break;
 543                 }
 544                 /* after notification unregisters process */
 545                 put_pid(info->notify_owner);
 546                 info->notify_owner = NULL;
 547         }
 548         wake_up(&info->wait_q);
 549 }
 550
 551 static long prepare_timeout(struct timespec *p)
 552 {
 553         struct timespec nowts;
 554         long timeout;
 555
 556         if (p) {
 557                 if (unlikely(p->tv_nsec < 0 || p->tv_sec < 0
 558                         || p->tv_nsec >= NSEC_PER_SEC))
 559                         return -EINVAL;
 560                 nowts = CURRENT_TIME;
 561                 /* first subtract as jiffies can't be too big */
 562                 p->tv_sec -= nowts.tv_sec;
 563                 if (p->tv_nsec < nowts.tv_nsec) {
 564                         p->tv_nsec += NSEC_PER_SEC;
 565                         p->tv_sec--;
 566                 }
 567                 p->tv_nsec -= nowts.tv_nsec;
 568                 if (p->tv_sec < 0)
 569                         return 0;
 570
 571                 timeout = timespec_to_jiffies(p) + 1;
 572         } else
 573                 return MAX_SCHEDULE_TIMEOUT;
 574
 575         return timeout;
 576 }
 577
 578 static void remove_notification(struct mqueue_inode_info *info)
 579 {
 580         if (info->notify_owner != NULL &&
 581             info->notify.sigev_notify == SIGEV_THREAD) {
 582                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
 583                 netlink_sendskb(info->notify_sock, info->notify_cookie);
 584         }
 585         put_pid(info->notify_owner);
 586         info->notify_owner = NULL;
 587 }
 588
 589 static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
 590 {
 591         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
 592                 return 0;
 593         if (capable(CAP_SYS_RESOURCE)) {
 594                 if (attr->mq_maxmsg > HARD_MSGMAX)
 595                         return 0;
 596         } else {
 597                 if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
 598                                 attr->mq_msgsize > ipc_ns->mq_msgsize_max)
 599                         return 0;
 600         }
 601         /* check for overflow */
 602         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
 603                 return 0;
 604         if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
 605             (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
 606             (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
 607                 return 0;
 608         return 1;
 609 }
 610
 611 /*
 612  * Invoked when creating a new queue via sys_mq_open
 613  */
 614 static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir,
 615                         struct dentry *dentry, int oflag, mode_t mode,
 616                         struct mq_attr *attr)
 617 {
 618         const struct cred *cred = current_cred();
 619         struct file *result;
 620         int ret;
 621
 622         if (attr) {
 623                 ret = -EINVAL;
 624                 if (!mq_attr_ok(ipc_ns, attr))
 625                         goto out;
 626                 /* store for use during create */
 627                 dentry->d_fsdata = attr;
 628         }
 629
 630         mode &= ~current_umask();
 631         ret = mnt_want_write(ipc_ns->mq_mnt);
 632         if (ret)
 633                 goto out;
 634         ret = vfs_create(dir->d_inode, dentry, mode, NULL);
 635         dentry->d_fsdata = NULL;
 636         if (ret)
 637                 goto out_drop_write;
 638
 639         result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
 640         /*
 641          * dentry_open() took a persistent mnt_want_write(),
 642          * so we can now drop this one.
 643          */
 644         mnt_drop_write(ipc_ns->mq_mnt);
 645         return result;
 646
 647 out_drop_write:
 648         mnt_drop_write(ipc_ns->mq_mnt);
 649 out:
 650         dput(dentry);
 651         mntput(ipc_ns->mq_mnt);
 652         return ERR_PTR(ret);
 653 }
 654
 655 /* Opens existing queue */
 656 static struct file *do_open(struct ipc_namespace *ipc_ns,
 657                                 struct dentry *dentry, int oflag)
 658 {
 659         const struct cred *cred = current_cred();
 660
 661         static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
 662                                                   MAY_READ | MAY_WRITE };
 663
 664         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
 665                 dput(dentry);
 666                 mntput(ipc_ns->mq_mnt);
 667                 return ERR_PTR(-EINVAL);
 668         }
 669
 670         if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
 671                 dput(dentry);
 672                 mntput(ipc_ns->mq_mnt);
 673                 return ERR_PTR(-EACCES);
 674         }
 675
 676         return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
 677 }
 678
 679 SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, mode_t, mode,
 680                 struct mq_attr __user *, u_attr)
 681 {
 682         struct dentry *dentry;
 683         struct file *filp;
 684         char *name;
 685         struct mq_attr attr;
 686         int fd, error;
 687         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
 688
 689         if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
 690                 return -EFAULT;
 691
 692         audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
 693
 694         if (IS_ERR(name = getname(u_name)))
 695                 return PTR_ERR(name);
 696
 697         fd = get_unused_fd_flags(O_CLOEXEC);
 698         if (fd < 0)
 699                 goto out_putname;
 700
 701         mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 702         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
 703         if (IS_ERR(dentry)) {
 704                 error = PTR_ERR(dentry);
 705                 goto out_putfd;
 706         }
 707         mntget(ipc_ns->mq_mnt);
 708
 709         if (oflag & O_CREAT) {
 710                 if (dentry->d_inode) {  /* entry already exists */
 711                         audit_inode(name, dentry);
 712                         error = -EEXIST;
 713                         if (oflag & O_EXCL)
 714                                 goto out;
 715                         filp = do_open(ipc_ns, dentry, oflag);
 716                 } else {
 717                         filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root,
 718                                                 dentry, oflag, mode,
 719                                                 u_attr ? &attr : NULL);
 720                 }
 721         } else {
 722                 error = -ENOENT;
 723                 if (!dentry->d_inode)
 724                         goto out;
 725                 audit_inode(name, dentry);
 726                 filp = do_open(ipc_ns, dentry, oflag);
 727         }
 728
 729         if (IS_ERR(filp)) {
 730                 error = PTR_ERR(filp);
 731                 goto out_putfd;
 732         }
 733
 734         fd_install(fd, filp);
 735         goto out_upsem;
 736
 737 out:
 738         dput(dentry);
 739         mntput(ipc_ns->mq_mnt);
 740 out_putfd:
 741         put_unused_fd(fd);
 742         fd = error;
 743 out_upsem:
 744         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 745 out_putname:
 746         putname(name);
 747         return fd;
 748 }
 749
 750 SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
 751 {
 752         int err;
 753         char *name;
 754         struct dentry *dentry;
 755         struct inode *inode = NULL;
 756         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
 757
 758         name = getname(u_name);
 759         if (IS_ERR(name))
 760                 return PTR_ERR(name);
 761
 762         mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
 763                         I_MUTEX_PARENT);
 764         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
 765         if (IS_ERR(dentry)) {
 766                 err = PTR_ERR(dentry);
 767                 goto out_unlock;
 768         }
 769
 770         if (!dentry->d_inode) {
 771                 err = -ENOENT;
 772                 goto out_err;
 773         }
 774
 775         inode = dentry->d_inode;
 776         if (inode)
 777                 atomic_inc(&inode->i_count);
 778         err = mnt_want_write(ipc_ns->mq_mnt);
 779         if (err)
 780                 goto out_err;
 781         err = vfs_unlink(dentry->d_parent->d_inode, dentry);
 782         mnt_drop_write(ipc_ns->mq_mnt);
 783 out_err:
 784         dput(dentry);
 785
 786 out_unlock:
 787         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 788         putname(name);
 789         if (inode)
 790                 iput(inode);
 791
 792         return err;
 793 }
 794
 795 /* Pipelined send and receive functions.
 796  *
 797  * If a receiver finds no waiting message, then it registers itself in the
 798  * list of waiting receivers. A sender checks that list before adding the new
 799  * message into the message array. If there is a waiting receiver, then it
 800  * bypasses the message array and directly hands the message over to the
 801  * receiver.
 802  * The receiver accepts the message and returns without grabbing the queue
 803  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
 804  * are necessary. The same algorithm is used for sysv semaphores, see
 805  * ipc/sem.c for more details.
 806  *
 807  * The same algorithm is used for senders.
 808  */
 809
 810 /* pipelined_send() - send a message directly to the task waiting in
 811  * sys_mq_timedreceive() (without inserting message into a queue).
 812  */
 813 static inline void pipelined_send(struct mqueue_inode_info *info,
 814                                   struct msg_msg *message,
 815                                   struct ext_wait_queue *receiver)
 816 {
 817         receiver->msg = message;
 818         list_del(&receiver->list);
 819         receiver->state = STATE_PENDING;
 820         wake_up_process(receiver->task);
 821         smp_wmb();
 822         receiver->state = STATE_READY;
 823 }
 824
 825 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
 826  * gets its message and put to the queue (we have one free place for sure). */
 827 static inline void pipelined_receive(struct mqueue_inode_info *info)
 828 {
 829         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
 830
 831         if (!sender) {
 832                 /* for poll */
 833                 wake_up_interruptible(&info->wait_q);
 834                 return;
 835         }
 836         msg_insert(sender->msg, info);
 837         list_del(&sender->list);
 838         sender->state = STATE_PENDING;
 839         wake_up_process(sender->task);
 840         smp_wmb();
 841         sender->state = STATE_READY;
 842 }
 843
 844 SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
 845                 size_t, msg_len, unsigned int, msg_prio,
 846                 const struct timespec __user *, u_abs_timeout)
 847 {
 848         struct file *filp;
 849         struct inode *inode;
 850         struct ext_wait_queue wait;
 851         struct ext_wait_queue *receiver;
 852         struct msg_msg *msg_ptr;
 853         struct mqueue_inode_info *info;
 854         struct timespec ts, *p = NULL;
 855         long timeout;
 856         int ret;
 857
 858         if (u_abs_timeout) {
 859                 if (copy_from_user(&ts, u_abs_timeout,
 860                                         sizeof(struct timespec)))
 861                         return -EFAULT;
 862                 p = &ts;
 863         }
 864
 865         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
 866                 return -EINVAL;
 867
 868         audit_mq_sendrecv(mqdes, msg_len, msg_prio, p);
 869         timeout = prepare_timeout(p);
 870
 871         ret = -EBADF;
 872         filp = fget(mqdes);
 873         if (unlikely(!filp))
 874                 goto out;
 875
 876         inode = filp->f_path.dentry->d_inode;
 877         if (unlikely(filp->f_op != &mqueue_file_operations))
 878                 goto out_fput;
 879         info = MQUEUE_I(inode);
 880         audit_inode(NULL, filp->f_path.dentry);
 881
 882         if (unlikely(!(filp->f_mode & FMODE_WRITE)))
 883                 goto out_fput;
 884
 885         if (unlikely(msg_len > info->attr.mq_msgsize)) {
 886                 ret = -EMSGSIZE;
 887                 goto out_fput;
 888         }
 889
 890         /* First try to allocate memory, before doing anything with
 891          * existing queues. */
 892         msg_ptr = load_msg(u_msg_ptr, msg_len);
 893         if (IS_ERR(msg_ptr)) {
 894                 ret = PTR_ERR(msg_ptr);
 895                 goto out_fput;
 896         }
 897         msg_ptr->m_ts = msg_len;
 898         msg_ptr->m_type = msg_prio;
 899
 900         spin_lock(&info->lock);
 901
 902         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
 903                 if (filp->f_flags & O_NONBLOCK) {
 904                         spin_unlock(&info->lock);
 905                         ret = -EAGAIN;
 906                 } else if (unlikely(timeout < 0)) {
 907                         spin_unlock(&info->lock);
 908                         ret = timeout;
 909                 } else {
 910                         wait.task = current;
 911                         wait.msg = (void *) msg_ptr;
 912                         wait.state = STATE_NONE;
 913                         ret = wq_sleep(info, SEND, timeout, &wait);
 914                 }
 915                 if (ret < 0)
 916                         free_msg(msg_ptr);
 917         } else {
 918                 receiver = wq_get_first_waiter(info, RECV);
 919                 if (receiver) {
 920                         pipelined_send(info, msg_ptr, receiver);
 921                 } else {
 922                         /* adds message to the queue */
 923                         msg_insert(msg_ptr, info);
 924                         __do_notify(info);
 925                 }
 926                 inode->i_atime = inode->i_mtime = inode->i_ctime =
 927                                 CURRENT_TIME;
 928                 spin_unlock(&info->lock);
 929                 ret = 0;
 930         }
 931 out_fput:
 932         fput(filp);
 933 out:
 934         return ret;
 935 }
 936
 937 SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
 938                 size_t, msg_len, unsigned int __user *, u_msg_prio,
 939                 const struct timespec __user *, u_abs_timeout)
 940 {
 941         long timeout;
 942         ssize_t ret;
 943         struct msg_msg *msg_ptr;
 944         struct file *filp;
 945         struct inode *inode;
 946         struct mqueue_inode_info *info;
 947         struct ext_wait_queue wait;
 948         struct timespec ts, *p = NULL;
 949
 950         if (u_abs_timeout) {
 951                 if (copy_from_user(&ts, u_abs_timeout,
 952                                         sizeof(struct timespec)))
 953                         return -EFAULT;
 954                 p = &ts;
 955         }
 956
 957         audit_mq_sendrecv(mqdes, msg_len, 0, p);
 958         timeout = prepare_timeout(p);
 959
 960         ret = -EBADF;
 961         filp = fget(mqdes);
 962         if (unlikely(!filp))
 963                 goto out;
 964
 965         inode = filp->f_path.dentry->d_inode;
 966         if (unlikely(filp->f_op != &mqueue_file_operations))
 967                 goto out_fput;
 968         info = MQUEUE_I(inode);
 969         audit_inode(NULL, filp->f_path.dentry);
 970
 971         if (unlikely(!(filp->f_mode & FMODE_READ)))
 972                 goto out_fput;
 973
 974         /* checks if buffer is big enough */
 975         if (unlikely(msg_len < info->attr.mq_msgsize)) {
 976                 ret = -EMSGSIZE;
 977                 goto out_fput;
 978         }
 979
 980         spin_lock(&info->lock);
 981         if (info->attr.mq_curmsgs == 0) {
 982                 if (filp->f_flags & O_NONBLOCK) {
 983                         spin_unlock(&info->lock);
 984                         ret = -EAGAIN;
 985                         msg_ptr = NULL;
 986                 } else if (unlikely(timeout < 0)) {
 987                         spin_unlock(&info->lock);
 988                         ret = timeout;
 989                         msg_ptr = NULL;
 990                 } else {
 991                         wait.task = current;
 992                         wait.state = STATE_NONE;
 993                         ret = wq_sleep(info, RECV, timeout, &wait);
 994                         msg_ptr = wait.msg;
 995                 }
 996         } else {
 997                 msg_ptr = msg_get(info);
 998
 999                 inode->i_atime = inode->i_mtime = inode->i_ctime =
1000                                 CURRENT_TIME;
1001
1002                 /* There is now free space in queue. */
1003                 pipelined_receive(info);
1004                 spin_unlock(&info->lock);
1005                 ret = 0;
1006         }
1007         if (ret == 0) {
1008                 ret = msg_ptr->m_ts;
1009
1010                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1011                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1012                         ret = -EFAULT;
1013                 }
1014                 free_msg(msg_ptr);
1015         }
1016 out_fput:
1017         fput(filp);
1018 out:
1019         return ret;
1020 }
1021
1022 /*
1023  * Notes: the case when user wants us to deregister (with NULL as pointer)
1024  * and he isn't currently owner of notification, will be silently discarded.
1025  * It isn't explicitly defined in the POSIX.
1026  */
1027 SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1028                 const struct sigevent __user *, u_notification)
1029 {
1030         int ret;
1031         struct file *filp;
1032         struct sock *sock;
1033         struct inode *inode;
1034         struct sigevent notification;
1035         struct mqueue_inode_info *info;
1036         struct sk_buff *nc;
1037
1038         if (u_notification) {
1039                 if (copy_from_user(&notification, u_notification,
1040                                         sizeof(struct sigevent)))
1041                         return -EFAULT;
1042         }
1043
1044         audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1045
1046         nc = NULL;
1047         sock = NULL;
1048         if (u_notification != NULL) {
1049                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1050                              notification.sigev_notify != SIGEV_SIGNAL &&
1051                              notification.sigev_notify != SIGEV_THREAD))
1052                         return -EINVAL;
1053                 if (notification.sigev_notify == SIGEV_SIGNAL &&
1054                         !valid_signal(notification.sigev_signo)) {
1055                         return -EINVAL;
1056                 }
1057                 if (notification.sigev_notify == SIGEV_THREAD) {
1058                         long timeo;
1059
1060                         /* create the notify skb */
1061                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1062                         ret = -ENOMEM;
1063                         if (!nc)
1064                                 goto out;
1065                         ret = -EFAULT;
1066                         if (copy_from_user(nc->data,
1067                                         notification.sigev_value.sival_ptr,
1068                                         NOTIFY_COOKIE_LEN)) {
1069                                 goto out;
1070                         }
1071
1072                         /* TODO: add a header? */
1073                         skb_put(nc, NOTIFY_COOKIE_LEN);
1074                         /* and attach it to the socket */
1075 retry:
1076                         filp = fget(notification.sigev_signo);
1077                         ret = -EBADF;
1078                         if (!filp)
1079                                 goto out;
1080                         sock = netlink_getsockbyfilp(filp);
1081                         fput(filp);
1082                         if (IS_ERR(sock)) {
1083                                 ret = PTR_ERR(sock);
1084                                 sock = NULL;
1085                                 goto out;
1086                         }
1087
1088                         timeo = MAX_SCHEDULE_TIMEOUT;
1089                         ret = netlink_attachskb(sock, nc, &timeo, NULL);
1090                         if (ret == 1)
1091                                 goto retry;
1092                         if (ret) {
1093                                 sock = NULL;
1094                                 nc = NULL;
1095                                 goto out;
1096                         }
1097                 }
1098         }
1099
1100         ret = -EBADF;
1101         filp = fget(mqdes);
1102         if (!filp)
1103                 goto out;
1104
1105         inode = filp->f_path.dentry->d_inode;
1106         if (unlikely(filp->f_op != &mqueue_file_operations))
1107                 goto out_fput;
1108         info = MQUEUE_I(inode);
1109
1110         ret = 0;
1111         spin_lock(&info->lock);
1112         if (u_notification == NULL) {
1113                 if (info->notify_owner == task_tgid(current)) {
1114                         remove_notification(info);
1115                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1116                 }
1117         } else if (info->notify_owner != NULL) {
1118                 ret = -EBUSY;
1119         } else {
1120                 switch (notification.sigev_notify) {
1121                 case SIGEV_NONE:
1122                         info->notify.sigev_notify = SIGEV_NONE;
1123                         break;
1124                 case SIGEV_THREAD:
1125                         info->notify_sock = sock;
1126                         info->notify_cookie = nc;
1127                         sock = NULL;
1128                         nc = NULL;
1129                         info->notify.sigev_notify = SIGEV_THREAD;
1130                         break;
1131                 case SIGEV_SIGNAL:
1132                         info->notify.sigev_signo = notification.sigev_signo;
1133                         info->notify.sigev_value = notification.sigev_value;
1134                         info->notify.sigev_notify = SIGEV_SIGNAL;
1135                         break;
1136                 }
1137
1138                 info->notify_owner = get_pid(task_tgid(current));
1139                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1140         }
1141         spin_unlock(&info->lock);
1142 out_fput:
1143         fput(filp);
1144 out:
1145         if (sock) {
1146                 netlink_detachskb(sock, nc);
1147         } else if (nc) {
1148                 dev_kfree_skb(nc);
1149         }
1150         return ret;
1151 }
1152
1153 SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1154                 const struct mq_attr __user *, u_mqstat,
1155                 struct mq_attr __user *, u_omqstat)
1156 {
1157         int ret;
1158         struct mq_attr mqstat, omqstat;
1159         struct file *filp;
1160         struct inode *inode;
1161         struct mqueue_inode_info *info;
1162
1163         if (u_mqstat != NULL) {
1164                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1165                         return -EFAULT;
1166                 if (mqstat.mq_flags & (~O_NONBLOCK))
1167                         return -EINVAL;
1168         }
1169
1170         ret = -EBADF;
1171         filp = fget(mqdes);
1172         if (!filp)
1173                 goto out;
1174
1175         inode = filp->f_path.dentry->d_inode;
1176         if (unlikely(filp->f_op != &mqueue_file_operations))
1177                 goto out_fput;
1178         info = MQUEUE_I(inode);
1179
1180         spin_lock(&info->lock);
1181
1182         omqstat = info->attr;
1183         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1184         if (u_mqstat) {
1185                 audit_mq_getsetattr(mqdes, &mqstat);
1186                 spin_lock(&filp->f_lock);
1187                 if (mqstat.mq_flags & O_NONBLOCK)
1188                         filp->f_flags |= O_NONBLOCK;
1189                 else
1190                         filp->f_flags &= ~O_NONBLOCK;
1191                 spin_unlock(&filp->f_lock);
1192
1193                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1194         }
1195
1196         spin_unlock(&info->lock);
1197
1198         ret = 0;
1199         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1200                                                 sizeof(struct mq_attr)))
1201                 ret = -EFAULT;
1202
1203 out_fput:
1204         fput(filp);
1205 out:
1206         return ret;
1207 }
1208
1209 static const struct inode_operations mqueue_dir_inode_operations = {
1210         .lookup = simple_lookup,
1211         .create = mqueue_create,
1212         .unlink = mqueue_unlink,
1213 };
1214
1215 static const struct file_operations mqueue_file_operations = {
1216         .flush = mqueue_flush_file,
1217         .poll = mqueue_poll_file,
1218         .read = mqueue_read_file,
1219 };
1220
1221 static const struct super_operations mqueue_super_ops = {
1222         .alloc_inode = mqueue_alloc_inode,
1223         .destroy_inode = mqueue_destroy_inode,
1224         .statfs = simple_statfs,
1225         .delete_inode = mqueue_delete_inode,
1226         .drop_inode = generic_delete_inode,
1227 };
1228
1229 static struct file_system_type mqueue_fs_type = {
1230         .name = "mqueue",
1231         .get_sb = mqueue_get_sb,
1232         .kill_sb = kill_litter_super,
1233 };
1234
1235 int mq_init_ns(struct ipc_namespace *ns)
1236 {
1237         ns->mq_queues_count  = 0;
1238         ns->mq_queues_max    = DFLT_QUEUESMAX;
1239         ns->mq_msg_max       = DFLT_MSGMAX;
1240         ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1241
1242         ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1243         if (IS_ERR(ns->mq_mnt)) {
1244                 int err = PTR_ERR(ns->mq_mnt);
1245                 ns->mq_mnt = NULL;
1246                 return err;
1247         }
1248         return 0;
1249 }
1250
1251 void mq_clear_sbinfo(struct ipc_namespace *ns)
1252 {
1253         ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1254 }
1255
1256 void mq_put_mnt(struct ipc_namespace *ns)
1257 {
1258         mntput(ns->mq_mnt);
1259 }
1260
1261 static int __init init_mqueue_fs(void)
1262 {
1263         int error;
1264
1265         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1266                                 sizeof(struct mqueue_inode_info), 0,
1267                                 SLAB_HWCACHE_ALIGN, init_once);
1268         if (mqueue_inode_cachep == NULL)
1269                 return -ENOMEM;
1270
1271         /* ignore failues - they are not fatal */
1272         mq_sysctl_table = mq_register_sysctl_table();
1273
1274         error = register_filesystem(&mqueue_fs_type);
1275         if (error)
1276                 goto out_sysctl;
1277
1278         spin_lock_init(&mq_lock);
1279
1280         init_ipc_ns.mq_mnt = kern_mount_data(&mqueue_fs_type, &init_ipc_ns);
1281         if (IS_ERR(init_ipc_ns.mq_mnt)) {
1282                 error = PTR_ERR(init_ipc_ns.mq_mnt);
1283                 goto out_filesystem;
1284         }
1285
1286         return 0;
1287
1288 out_filesystem:
1289         unregister_filesystem(&mqueue_fs_type);
1290 out_sysctl:
1291         if (mq_sysctl_table)
1292                 unregister_sysctl_table(mq_sysctl_table);
1293         kmem_cache_destroy(mqueue_inode_cachep);
1294         return error;
1295 }
1296
1297 __initcall(init_mqueue_fs);