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 /*
  51  * Define the ranges various user-specified maximum values can
  52  * be set to.
  53  */
  54 #define MIN_MSGMAX      1               /* min value for msg_max */
  55 #define MAX_MSGMAX      HARD_MSGMAX     /* max value for msg_max */
  56 #define MIN_MSGSIZEMAX  128             /* min value for msgsize_max */
  57 #define MAX_MSGSIZEMAX  (8192*128)      /* max value for msgsize_max */
  58
  59 struct ext_wait_queue {         /* queue of sleeping tasks */
  60         struct task_struct *task;
  61         struct list_head list;
  62         struct msg_msg *msg;    /* ptr of loaded message */
  63         int state;              /* one of STATE_* values */
  64 };
  65
  66 struct mqueue_inode_info {
  67         spinlock_t lock;
  68         struct inode vfs_inode;
  69         wait_queue_head_t wait_q;
  70
  71         struct msg_msg **messages;
  72         struct mq_attr attr;
  73
  74         struct sigevent notify;
  75         struct pid* notify_owner;
  76         struct user_struct *user;       /* user who created, for accounting */
  77         struct sock *notify_sock;
  78         struct sk_buff *notify_cookie;
  79
  80         /* for tasks waiting for free space and messages, respectively */
  81         struct ext_wait_queue e_wait_q[2];
  82
  83         unsigned long qsize; /* size of queue in memory (sum of all msgs) */
  84 };
  85
  86 static const struct inode_operations mqueue_dir_inode_operations;
  87 static const struct file_operations mqueue_file_operations;
  88 static struct super_operations mqueue_super_ops;
  89 static void remove_notification(struct mqueue_inode_info *info);
  90
  91 static spinlock_t mq_lock;
  92 static struct kmem_cache *mqueue_inode_cachep;
  93
  94 static struct ctl_table_header * mq_sysctl_table;
  95
  96 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
  97 {
  98         return container_of(inode, struct mqueue_inode_info, vfs_inode);
  99 }
 100
 101 void mq_init_ns(struct ipc_namespace *ns)
 102 {
 103         ns->mq_queues_count  = 0;
 104         ns->mq_queues_max    = DFLT_QUEUESMAX;
 105         ns->mq_msg_max       = DFLT_MSGMAX;
 106         ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
 107         ns->mq_mnt           = mntget(init_ipc_ns.mq_mnt);
 108 }
 109
 110 void mq_exit_ns(struct ipc_namespace *ns)
 111 {
 112         /* will need to clear out ns->mq_mnt->mnt_sb->s_fs_info here */
 113         mntput(ns->mq_mnt);
 114 }
 115
 116 static struct inode *mqueue_get_inode(struct super_block *sb, int mode,
 117                                                         struct mq_attr *attr)
 118 {
 119         struct user_struct *u = current_user();
 120         struct inode *inode;
 121         struct ipc_namespace *ipc_ns = &init_ipc_ns;
 122
 123         inode = new_inode(sb);
 124         if (inode) {
 125                 inode->i_mode = mode;
 126                 inode->i_uid = current_fsuid();
 127                 inode->i_gid = current_fsgid();
 128                 inode->i_mtime = inode->i_ctime = inode->i_atime =
 129                                 CURRENT_TIME;
 130
 131                 if (S_ISREG(mode)) {
 132                         struct mqueue_inode_info *info;
 133                         struct task_struct *p = current;
 134                         unsigned long mq_bytes, mq_msg_tblsz;
 135
 136                         inode->i_fop = &mqueue_file_operations;
 137                         inode->i_size = FILENT_SIZE;
 138                         /* mqueue specific info */
 139                         info = MQUEUE_I(inode);
 140                         spin_lock_init(&info->lock);
 141                         init_waitqueue_head(&info->wait_q);
 142                         INIT_LIST_HEAD(&info->e_wait_q[0].list);
 143                         INIT_LIST_HEAD(&info->e_wait_q[1].list);
 144                         info->messages = NULL;
 145                         info->notify_owner = NULL;
 146                         info->qsize = 0;
 147                         info->user = NULL;      /* set when all is ok */
 148                         memset(&info->attr, 0, sizeof(info->attr));
 149                         info->attr.mq_maxmsg = ipc_ns->mq_msg_max;
 150                         info->attr.mq_msgsize = ipc_ns->mq_msgsize_max;
 151                         if (attr) {
 152                                 info->attr.mq_maxmsg = attr->mq_maxmsg;
 153                                 info->attr.mq_msgsize = attr->mq_msgsize;
 154                         }
 155                         mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
 156                         mq_bytes = (mq_msg_tblsz +
 157                                 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
 158
 159                         spin_lock(&mq_lock);
 160                         if (u->mq_bytes + mq_bytes < u->mq_bytes ||
 161                             u->mq_bytes + mq_bytes >
 162                             p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
 163                                 spin_unlock(&mq_lock);
 164                                 goto out_inode;
 165                         }
 166                         u->mq_bytes += mq_bytes;
 167                         spin_unlock(&mq_lock);
 168
 169                         info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
 170                         if (!info->messages) {
 171                                 spin_lock(&mq_lock);
 172                                 u->mq_bytes -= mq_bytes;
 173                                 spin_unlock(&mq_lock);
 174                                 goto out_inode;
 175                         }
 176                         /* all is ok */
 177                         info->user = get_uid(u);
 178                 } else if (S_ISDIR(mode)) {
 179                         inc_nlink(inode);
 180                         /* Some things misbehave if size == 0 on a directory */
 181                         inode->i_size = 2 * DIRENT_SIZE;
 182                         inode->i_op = &mqueue_dir_inode_operations;
 183                         inode->i_fop = &simple_dir_operations;
 184                 }
 185         }
 186         return inode;
 187 out_inode:
 188         make_bad_inode(inode);
 189         iput(inode);
 190         return NULL;
 191 }
 192
 193 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
 194 {
 195         struct inode *inode;
 196
 197         sb->s_blocksize = PAGE_CACHE_SIZE;
 198         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 199         sb->s_magic = MQUEUE_MAGIC;
 200         sb->s_op = &mqueue_super_ops;
 201
 202         inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
 203         if (!inode)
 204                 return -ENOMEM;
 205
 206         sb->s_root = d_alloc_root(inode);
 207         if (!sb->s_root) {
 208                 iput(inode);
 209                 return -ENOMEM;
 210         }
 211
 212         return 0;
 213 }
 214
 215 static int mqueue_get_sb(struct file_system_type *fs_type,
 216                          int flags, const char *dev_name,
 217                          void *data, struct vfsmount *mnt)
 218 {
 219         return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt);
 220 }
 221
 222 static void init_once(void *foo)
 223 {
 224         struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
 225
 226         inode_init_once(&p->vfs_inode);
 227 }
 228
 229 static struct inode *mqueue_alloc_inode(struct super_block *sb)
 230 {
 231         struct mqueue_inode_info *ei;
 232
 233         ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
 234         if (!ei)
 235                 return NULL;
 236         return &ei->vfs_inode;
 237 }
 238
 239 static void mqueue_destroy_inode(struct inode *inode)
 240 {
 241         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
 242 }
 243
 244 static void mqueue_delete_inode(struct inode *inode)
 245 {
 246         struct mqueue_inode_info *info;
 247         struct user_struct *user;
 248         unsigned long mq_bytes;
 249         int i;
 250         struct ipc_namespace *ipc_ns = &init_ipc_ns;
 251
 252         if (S_ISDIR(inode->i_mode)) {
 253                 clear_inode(inode);
 254                 return;
 255         }
 256         info = MQUEUE_I(inode);
 257         spin_lock(&info->lock);
 258         for (i = 0; i < info->attr.mq_curmsgs; i++)
 259                 free_msg(info->messages[i]);
 260         kfree(info->messages);
 261         spin_unlock(&info->lock);
 262
 263         clear_inode(inode);
 264
 265         mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
 266                    (info->attr.mq_maxmsg * info->attr.mq_msgsize));
 267         user = info->user;
 268         if (user) {
 269                 spin_lock(&mq_lock);
 270                 user->mq_bytes -= mq_bytes;
 271                 ipc_ns->mq_queues_count--;
 272                 spin_unlock(&mq_lock);
 273                 free_uid(user);
 274         }
 275 }
 276
 277 static int mqueue_create(struct inode *dir, struct dentry *dentry,
 278                                 int mode, struct nameidata *nd)
 279 {
 280         struct inode *inode;
 281         struct mq_attr *attr = dentry->d_fsdata;
 282         int error;
 283         struct ipc_namespace *ipc_ns = &init_ipc_ns;
 284
 285         spin_lock(&mq_lock);
 286         if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
 287                         !capable(CAP_SYS_RESOURCE)) {
 288                 error = -ENOSPC;
 289                 goto out_unlock;
 290         }
 291         ipc_ns->mq_queues_count++;
 292         spin_unlock(&mq_lock);
 293
 294         inode = mqueue_get_inode(dir->i_sb, mode, attr);
 295         if (!inode) {
 296                 error = -ENOMEM;
 297                 spin_lock(&mq_lock);
 298                 ipc_ns->mq_queues_count--;
 299                 goto out_unlock;
 300         }
 301
 302         dir->i_size += DIRENT_SIZE;
 303         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 304
 305         d_instantiate(dentry, inode);
 306         dget(dentry);
 307         return 0;
 308 out_unlock:
 309         spin_unlock(&mq_lock);
 310         return error;
 311 }
 312
 313 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
 314 {
 315         struct inode *inode = dentry->d_inode;
 316
 317         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 318         dir->i_size -= DIRENT_SIZE;
 319         drop_nlink(inode);
 320         dput(dentry);
 321         return 0;
 322 }
 323
 324 /*
 325 *       This is routine for system read from queue file.
 326 *       To avoid mess with doing here some sort of mq_receive we allow
 327 *       to read only queue size & notification info (the only values
 328 *       that are interesting from user point of view and aren't accessible
 329 *       through std routines)
 330 */
 331 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
 332                                 size_t count, loff_t *off)
 333 {
 334         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 335         char buffer[FILENT_SIZE];
 336         ssize_t ret;
 337
 338         spin_lock(&info->lock);
 339         snprintf(buffer, sizeof(buffer),
 340                         "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
 341                         info->qsize,
 342                         info->notify_owner ? info->notify.sigev_notify : 0,
 343                         (info->notify_owner &&
 344                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
 345                                 info->notify.sigev_signo : 0,
 346                         pid_vnr(info->notify_owner));
 347         spin_unlock(&info->lock);
 348         buffer[sizeof(buffer)-1] = '\0';
 349
 350         ret = simple_read_from_buffer(u_data, count, off, buffer,
 351                                 strlen(buffer));
 352         if (ret <= 0)
 353                 return ret;
 354
 355         filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
 356         return ret;
 357 }
 358
 359 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
 360 {
 361         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 362
 363         spin_lock(&info->lock);
 364         if (task_tgid(current) == info->notify_owner)
 365                 remove_notification(info);
 366
 367         spin_unlock(&info->lock);
 368         return 0;
 369 }
 370
 371 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
 372 {
 373         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 374         int retval = 0;
 375
 376         poll_wait(filp, &info->wait_q, poll_tab);
 377
 378         spin_lock(&info->lock);
 379         if (info->attr.mq_curmsgs)
 380                 retval = POLLIN | POLLRDNORM;
 381
 382         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
 383                 retval |= POLLOUT | POLLWRNORM;
 384         spin_unlock(&info->lock);
 385
 386         return retval;
 387 }
 388
 389 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
 390 static void wq_add(struct mqueue_inode_info *info, int sr,
 391                         struct ext_wait_queue *ewp)
 392 {
 393         struct ext_wait_queue *walk;
 394
 395         ewp->task = current;
 396
 397         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
 398                 if (walk->task->static_prio <= current->static_prio) {
 399                         list_add_tail(&ewp->list, &walk->list);
 400                         return;
 401                 }
 402         }
 403         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
 404 }
 405
 406 /*
 407  * Puts current task to sleep. Caller must hold queue lock. After return
 408  * lock isn't held.
 409  * sr: SEND or RECV
 410  */
 411 static int wq_sleep(struct mqueue_inode_info *info, int sr,
 412                         long timeout, struct ext_wait_queue *ewp)
 413 {
 414         int retval;
 415         signed long time;
 416
 417         wq_add(info, sr, ewp);
 418
 419         for (;;) {
 420                 set_current_state(TASK_INTERRUPTIBLE);
 421
 422                 spin_unlock(&info->lock);
 423                 time = schedule_timeout(timeout);
 424
 425                 while (ewp->state == STATE_PENDING)
 426                         cpu_relax();
 427
 428                 if (ewp->state == STATE_READY) {
 429                         retval = 0;
 430                         goto out;
 431                 }
 432                 spin_lock(&info->lock);
 433                 if (ewp->state == STATE_READY) {
 434                         retval = 0;
 435                         goto out_unlock;
 436                 }
 437                 if (signal_pending(current)) {
 438                         retval = -ERESTARTSYS;
 439                         break;
 440                 }
 441                 if (time == 0) {
 442                         retval = -ETIMEDOUT;
 443                         break;
 444                 }
 445         }
 446         list_del(&ewp->list);
 447 out_unlock:
 448         spin_unlock(&info->lock);
 449 out:
 450         return retval;
 451 }
 452
 453 /*
 454  * Returns waiting task that should be serviced first or NULL if none exists
 455  */
 456 static struct ext_wait_queue *wq_get_first_waiter(
 457                 struct mqueue_inode_info *info, int sr)
 458 {
 459         struct list_head *ptr;
 460
 461         ptr = info->e_wait_q[sr].list.prev;
 462         if (ptr == &info->e_wait_q[sr].list)
 463                 return NULL;
 464         return list_entry(ptr, struct ext_wait_queue, list);
 465 }
 466
 467 /* Auxiliary functions to manipulate messages' list */
 468 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
 469 {
 470         int k;
 471
 472         k = info->attr.mq_curmsgs - 1;
 473         while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
 474                 info->messages[k + 1] = info->messages[k];
 475                 k--;
 476         }
 477         info->attr.mq_curmsgs++;
 478         info->qsize += ptr->m_ts;
 479         info->messages[k + 1] = ptr;
 480 }
 481
 482 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
 483 {
 484         info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
 485         return info->messages[info->attr.mq_curmsgs];
 486 }
 487
 488 static inline void set_cookie(struct sk_buff *skb, char code)
 489 {
 490         ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
 491 }
 492
 493 /*
 494  * The next function is only to split too long sys_mq_timedsend
 495  */
 496 static void __do_notify(struct mqueue_inode_info *info)
 497 {
 498         /* notification
 499          * invoked when there is registered process and there isn't process
 500          * waiting synchronously for message AND state of queue changed from
 501          * empty to not empty. Here we are sure that no one is waiting
 502          * synchronously. */
 503         if (info->notify_owner &&
 504             info->attr.mq_curmsgs == 1) {
 505                 struct siginfo sig_i;
 506                 switch (info->notify.sigev_notify) {
 507                 case SIGEV_NONE:
 508                         break;
 509                 case SIGEV_SIGNAL:
 510                         /* sends signal */
 511
 512                         sig_i.si_signo = info->notify.sigev_signo;
 513                         sig_i.si_errno = 0;
 514                         sig_i.si_code = SI_MESGQ;
 515                         sig_i.si_value = info->notify.sigev_value;
 516                         sig_i.si_pid = task_tgid_nr_ns(current,
 517                                                 ns_of_pid(info->notify_owner));
 518                         sig_i.si_uid = current_uid();
 519
 520                         kill_pid_info(info->notify.sigev_signo,
 521                                       &sig_i, info->notify_owner);
 522                         break;
 523                 case SIGEV_THREAD:
 524                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
 525                         netlink_sendskb(info->notify_sock, info->notify_cookie);
 526                         break;
 527                 }
 528                 /* after notification unregisters process */
 529                 put_pid(info->notify_owner);
 530                 info->notify_owner = NULL;
 531         }
 532         wake_up(&info->wait_q);
 533 }
 534
 535 static long prepare_timeout(struct timespec *p)
 536 {
 537         struct timespec nowts;
 538         long timeout;
 539
 540         if (p) {
 541                 if (unlikely(p->tv_nsec < 0 || p->tv_sec < 0
 542                         || p->tv_nsec >= NSEC_PER_SEC))
 543                         return -EINVAL;
 544                 nowts = CURRENT_TIME;
 545                 /* first subtract as jiffies can't be too big */
 546                 p->tv_sec -= nowts.tv_sec;
 547                 if (p->tv_nsec < nowts.tv_nsec) {
 548                         p->tv_nsec += NSEC_PER_SEC;
 549                         p->tv_sec--;
 550                 }
 551                 p->tv_nsec -= nowts.tv_nsec;
 552                 if (p->tv_sec < 0)
 553                         return 0;
 554
 555                 timeout = timespec_to_jiffies(p) + 1;
 556         } else
 557                 return MAX_SCHEDULE_TIMEOUT;
 558
 559         return timeout;
 560 }
 561
 562 static void remove_notification(struct mqueue_inode_info *info)
 563 {
 564         if (info->notify_owner != NULL &&
 565             info->notify.sigev_notify == SIGEV_THREAD) {
 566                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
 567                 netlink_sendskb(info->notify_sock, info->notify_cookie);
 568         }
 569         put_pid(info->notify_owner);
 570         info->notify_owner = NULL;
 571 }
 572
 573 static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
 574 {
 575         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
 576                 return 0;
 577         if (capable(CAP_SYS_RESOURCE)) {
 578                 if (attr->mq_maxmsg > HARD_MSGMAX)
 579                         return 0;
 580         } else {
 581                 if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
 582                                 attr->mq_msgsize > ipc_ns->mq_msgsize_max)
 583                         return 0;
 584         }
 585         /* check for overflow */
 586         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
 587                 return 0;
 588         if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
 589             (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
 590             (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
 591                 return 0;
 592         return 1;
 593 }
 594
 595 /*
 596  * Invoked when creating a new queue via sys_mq_open
 597  */
 598 static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir,
 599                         struct dentry *dentry, int oflag, mode_t mode,
 600                         struct mq_attr *attr)
 601 {
 602         const struct cred *cred = current_cred();
 603         struct file *result;
 604         int ret;
 605
 606         if (attr) {
 607                 ret = -EINVAL;
 608                 if (!mq_attr_ok(ipc_ns, attr))
 609                         goto out;
 610                 /* store for use during create */
 611                 dentry->d_fsdata = attr;
 612         }
 613
 614         mode &= ~current_umask();
 615         ret = mnt_want_write(ipc_ns->mq_mnt);
 616         if (ret)
 617                 goto out;
 618         ret = vfs_create(dir->d_inode, dentry, mode, NULL);
 619         dentry->d_fsdata = NULL;
 620         if (ret)
 621                 goto out_drop_write;
 622
 623         result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
 624         /*
 625          * dentry_open() took a persistent mnt_want_write(),
 626          * so we can now drop this one.
 627          */
 628         mnt_drop_write(ipc_ns->mq_mnt);
 629         return result;
 630
 631 out_drop_write:
 632         mnt_drop_write(ipc_ns->mq_mnt);
 633 out:
 634         dput(dentry);
 635         mntput(ipc_ns->mq_mnt);
 636         return ERR_PTR(ret);
 637 }
 638
 639 /* Opens existing queue */
 640 static struct file *do_open(struct ipc_namespace *ipc_ns,
 641                                 struct dentry *dentry, int oflag)
 642 {
 643         const struct cred *cred = current_cred();
 644
 645         static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
 646                                                   MAY_READ | MAY_WRITE };
 647
 648         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
 649                 dput(dentry);
 650                 mntput(ipc_ns->mq_mnt);
 651                 return ERR_PTR(-EINVAL);
 652         }
 653
 654         if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
 655                 dput(dentry);
 656                 mntput(ipc_ns->mq_mnt);
 657                 return ERR_PTR(-EACCES);
 658         }
 659
 660         return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
 661 }
 662
 663 SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, mode_t, mode,
 664                 struct mq_attr __user *, u_attr)
 665 {
 666         struct dentry *dentry;
 667         struct file *filp;
 668         char *name;
 669         struct mq_attr attr;
 670         int fd, error;
 671         struct ipc_namespace *ipc_ns = &init_ipc_ns;
 672
 673         if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
 674                 return -EFAULT;
 675
 676         audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
 677
 678         if (IS_ERR(name = getname(u_name)))
 679                 return PTR_ERR(name);
 680
 681         fd = get_unused_fd_flags(O_CLOEXEC);
 682         if (fd < 0)
 683                 goto out_putname;
 684
 685         mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 686         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
 687         if (IS_ERR(dentry)) {
 688                 error = PTR_ERR(dentry);
 689                 goto out_err;
 690         }
 691         mntget(ipc_ns->mq_mnt);
 692
 693         if (oflag & O_CREAT) {
 694                 if (dentry->d_inode) {  /* entry already exists */
 695                         audit_inode(name, dentry);
 696                         error = -EEXIST;
 697                         if (oflag & O_EXCL)
 698                                 goto out;
 699                         filp = do_open(ipc_ns, dentry, oflag);
 700                 } else {
 701                         filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root,
 702                                                 dentry, oflag, mode,
 703                                                 u_attr ? &attr : NULL);
 704                 }
 705         } else {
 706                 error = -ENOENT;
 707                 if (!dentry->d_inode)
 708                         goto out;
 709                 audit_inode(name, dentry);
 710                 filp = do_open(ipc_ns, dentry, oflag);
 711         }
 712
 713         if (IS_ERR(filp)) {
 714                 error = PTR_ERR(filp);
 715                 goto out_putfd;
 716         }
 717
 718         fd_install(fd, filp);
 719         goto out_upsem;
 720
 721 out:
 722         dput(dentry);
 723         mntput(ipc_ns->mq_mnt);
 724 out_putfd:
 725         put_unused_fd(fd);
 726 out_err:
 727         fd = error;
 728 out_upsem:
 729         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 730 out_putname:
 731         putname(name);
 732         return fd;
 733 }
 734
 735 SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
 736 {
 737         int err;
 738         char *name;
 739         struct dentry *dentry;
 740         struct inode *inode = NULL;
 741         struct ipc_namespace *ipc_ns = &init_ipc_ns;
 742
 743         name = getname(u_name);
 744         if (IS_ERR(name))
 745                 return PTR_ERR(name);
 746
 747         mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
 748                         I_MUTEX_PARENT);
 749         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
 750         if (IS_ERR(dentry)) {
 751                 err = PTR_ERR(dentry);
 752                 goto out_unlock;
 753         }
 754
 755         if (!dentry->d_inode) {
 756                 err = -ENOENT;
 757                 goto out_err;
 758         }
 759
 760         inode = dentry->d_inode;
 761         if (inode)
 762                 atomic_inc(&inode->i_count);
 763         err = mnt_want_write(ipc_ns->mq_mnt);
 764         if (err)
 765                 goto out_err;
 766         err = vfs_unlink(dentry->d_parent->d_inode, dentry);
 767         mnt_drop_write(ipc_ns->mq_mnt);
 768 out_err:
 769         dput(dentry);
 770
 771 out_unlock:
 772         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 773         putname(name);
 774         if (inode)
 775                 iput(inode);
 776
 777         return err;
 778 }
 779
 780 /* Pipelined send and receive functions.
 781  *
 782  * If a receiver finds no waiting message, then it registers itself in the
 783  * list of waiting receivers. A sender checks that list before adding the new
 784  * message into the message array. If there is a waiting receiver, then it
 785  * bypasses the message array and directly hands the message over to the
 786  * receiver.
 787  * The receiver accepts the message and returns without grabbing the queue
 788  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
 789  * are necessary. The same algorithm is used for sysv semaphores, see
 790  * ipc/sem.c for more details.
 791  *
 792  * The same algorithm is used for senders.
 793  */
 794
 795 /* pipelined_send() - send a message directly to the task waiting in
 796  * sys_mq_timedreceive() (without inserting message into a queue).
 797  */
 798 static inline void pipelined_send(struct mqueue_inode_info *info,
 799                                   struct msg_msg *message,
 800                                   struct ext_wait_queue *receiver)
 801 {
 802         receiver->msg = message;
 803         list_del(&receiver->list);
 804         receiver->state = STATE_PENDING;
 805         wake_up_process(receiver->task);
 806         smp_wmb();
 807         receiver->state = STATE_READY;
 808 }
 809
 810 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
 811  * gets its message and put to the queue (we have one free place for sure). */
 812 static inline void pipelined_receive(struct mqueue_inode_info *info)
 813 {
 814         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
 815
 816         if (!sender) {
 817                 /* for poll */
 818                 wake_up_interruptible(&info->wait_q);
 819                 return;
 820         }
 821         msg_insert(sender->msg, info);
 822         list_del(&sender->list);
 823         sender->state = STATE_PENDING;
 824         wake_up_process(sender->task);
 825         smp_wmb();
 826         sender->state = STATE_READY;
 827 }
 828
 829 SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
 830                 size_t, msg_len, unsigned int, msg_prio,
 831                 const struct timespec __user *, u_abs_timeout)
 832 {
 833         struct file *filp;
 834         struct inode *inode;
 835         struct ext_wait_queue wait;
 836         struct ext_wait_queue *receiver;
 837         struct msg_msg *msg_ptr;
 838         struct mqueue_inode_info *info;
 839         struct timespec ts, *p = NULL;
 840         long timeout;
 841         int ret;
 842
 843         if (u_abs_timeout) {
 844                 if (copy_from_user(&ts, u_abs_timeout,
 845                                         sizeof(struct timespec)))
 846                         return -EFAULT;
 847                 p = &ts;
 848         }
 849
 850         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
 851                 return -EINVAL;
 852
 853         audit_mq_sendrecv(mqdes, msg_len, msg_prio, p);
 854         timeout = prepare_timeout(p);
 855
 856         ret = -EBADF;
 857         filp = fget(mqdes);
 858         if (unlikely(!filp))
 859                 goto out;
 860
 861         inode = filp->f_path.dentry->d_inode;
 862         if (unlikely(filp->f_op != &mqueue_file_operations))
 863                 goto out_fput;
 864         info = MQUEUE_I(inode);
 865         audit_inode(NULL, filp->f_path.dentry);
 866
 867         if (unlikely(!(filp->f_mode & FMODE_WRITE)))
 868                 goto out_fput;
 869
 870         if (unlikely(msg_len > info->attr.mq_msgsize)) {
 871                 ret = -EMSGSIZE;
 872                 goto out_fput;
 873         }
 874
 875         /* First try to allocate memory, before doing anything with
 876          * existing queues. */
 877         msg_ptr = load_msg(u_msg_ptr, msg_len);
 878         if (IS_ERR(msg_ptr)) {
 879                 ret = PTR_ERR(msg_ptr);
 880                 goto out_fput;
 881         }
 882         msg_ptr->m_ts = msg_len;
 883         msg_ptr->m_type = msg_prio;
 884
 885         spin_lock(&info->lock);
 886
 887         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
 888                 if (filp->f_flags & O_NONBLOCK) {
 889                         spin_unlock(&info->lock);
 890                         ret = -EAGAIN;
 891                 } else if (unlikely(timeout < 0)) {
 892                         spin_unlock(&info->lock);
 893                         ret = timeout;
 894                 } else {
 895                         wait.task = current;
 896                         wait.msg = (void *) msg_ptr;
 897                         wait.state = STATE_NONE;
 898                         ret = wq_sleep(info, SEND, timeout, &wait);
 899                 }
 900                 if (ret < 0)
 901                         free_msg(msg_ptr);
 902         } else {
 903                 receiver = wq_get_first_waiter(info, RECV);
 904                 if (receiver) {
 905                         pipelined_send(info, msg_ptr, receiver);
 906                 } else {
 907                         /* adds message to the queue */
 908                         msg_insert(msg_ptr, info);
 909                         __do_notify(info);
 910                 }
 911                 inode->i_atime = inode->i_mtime = inode->i_ctime =
 912                                 CURRENT_TIME;
 913                 spin_unlock(&info->lock);
 914                 ret = 0;
 915         }
 916 out_fput:
 917         fput(filp);
 918 out:
 919         return ret;
 920 }
 921
 922 SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
 923                 size_t, msg_len, unsigned int __user *, u_msg_prio,
 924                 const struct timespec __user *, u_abs_timeout)
 925 {
 926         long timeout;
 927         ssize_t ret;
 928         struct msg_msg *msg_ptr;
 929         struct file *filp;
 930         struct inode *inode;
 931         struct mqueue_inode_info *info;
 932         struct ext_wait_queue wait;
 933         struct timespec ts, *p = NULL;
 934
 935         if (u_abs_timeout) {
 936                 if (copy_from_user(&ts, u_abs_timeout,
 937                                         sizeof(struct timespec)))
 938                         return -EFAULT;
 939                 p = &ts;
 940         }
 941
 942         audit_mq_sendrecv(mqdes, msg_len, 0, p);
 943         timeout = prepare_timeout(p);
 944
 945         ret = -EBADF;
 946         filp = fget(mqdes);
 947         if (unlikely(!filp))
 948                 goto out;
 949
 950         inode = filp->f_path.dentry->d_inode;
 951         if (unlikely(filp->f_op != &mqueue_file_operations))
 952                 goto out_fput;
 953         info = MQUEUE_I(inode);
 954         audit_inode(NULL, filp->f_path.dentry);
 955
 956         if (unlikely(!(filp->f_mode & FMODE_READ)))
 957                 goto out_fput;
 958
 959         /* checks if buffer is big enough */
 960         if (unlikely(msg_len < info->attr.mq_msgsize)) {
 961                 ret = -EMSGSIZE;
 962                 goto out_fput;
 963         }
 964
 965         spin_lock(&info->lock);
 966         if (info->attr.mq_curmsgs == 0) {
 967                 if (filp->f_flags & O_NONBLOCK) {
 968                         spin_unlock(&info->lock);
 969                         ret = -EAGAIN;
 970                         msg_ptr = NULL;
 971                 } else if (unlikely(timeout < 0)) {
 972                         spin_unlock(&info->lock);
 973                         ret = timeout;
 974                         msg_ptr = NULL;
 975                 } else {
 976                         wait.task = current;
 977                         wait.state = STATE_NONE;
 978                         ret = wq_sleep(info, RECV, timeout, &wait);
 979                         msg_ptr = wait.msg;
 980                 }
 981         } else {
 982                 msg_ptr = msg_get(info);
 983
 984                 inode->i_atime = inode->i_mtime = inode->i_ctime =
 985                                 CURRENT_TIME;
 986
 987                 /* There is now free space in queue. */
 988                 pipelined_receive(info);
 989                 spin_unlock(&info->lock);
 990                 ret = 0;
 991         }
 992         if (ret == 0) {
 993                 ret = msg_ptr->m_ts;
 994
 995                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
 996                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
 997                         ret = -EFAULT;
 998                 }
 999                 free_msg(msg_ptr);
1000         }
1001 out_fput:
1002         fput(filp);
1003 out:
1004         return ret;
1005 }
1006
1007 /*
1008  * Notes: the case when user wants us to deregister (with NULL as pointer)
1009  * and he isn't currently owner of notification, will be silently discarded.
1010  * It isn't explicitly defined in the POSIX.
1011  */
1012 SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1013                 const struct sigevent __user *, u_notification)
1014 {
1015         int ret;
1016         struct file *filp;
1017         struct sock *sock;
1018         struct inode *inode;
1019         struct sigevent notification;
1020         struct mqueue_inode_info *info;
1021         struct sk_buff *nc;
1022
1023         if (u_notification) {
1024                 if (copy_from_user(&notification, u_notification,
1025                                         sizeof(struct sigevent)))
1026                         return -EFAULT;
1027         }
1028
1029         audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1030
1031         nc = NULL;
1032         sock = NULL;
1033         if (u_notification != NULL) {
1034                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1035                              notification.sigev_notify != SIGEV_SIGNAL &&
1036                              notification.sigev_notify != SIGEV_THREAD))
1037                         return -EINVAL;
1038                 if (notification.sigev_notify == SIGEV_SIGNAL &&
1039                         !valid_signal(notification.sigev_signo)) {
1040                         return -EINVAL;
1041                 }
1042                 if (notification.sigev_notify == SIGEV_THREAD) {
1043                         long timeo;
1044
1045                         /* create the notify skb */
1046                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1047                         ret = -ENOMEM;
1048                         if (!nc)
1049                                 goto out;
1050                         ret = -EFAULT;
1051                         if (copy_from_user(nc->data,
1052                                         notification.sigev_value.sival_ptr,
1053                                         NOTIFY_COOKIE_LEN)) {
1054                                 goto out;
1055                         }
1056
1057                         /* TODO: add a header? */
1058                         skb_put(nc, NOTIFY_COOKIE_LEN);
1059                         /* and attach it to the socket */
1060 retry:
1061                         filp = fget(notification.sigev_signo);
1062                         ret = -EBADF;
1063                         if (!filp)
1064                                 goto out;
1065                         sock = netlink_getsockbyfilp(filp);
1066                         fput(filp);
1067                         if (IS_ERR(sock)) {
1068                                 ret = PTR_ERR(sock);
1069                                 sock = NULL;
1070                                 goto out;
1071                         }
1072
1073                         timeo = MAX_SCHEDULE_TIMEOUT;
1074                         ret = netlink_attachskb(sock, nc, &timeo, NULL);
1075                         if (ret == 1)
1076                                 goto retry;
1077                         if (ret) {
1078                                 sock = NULL;
1079                                 nc = NULL;
1080                                 goto out;
1081                         }
1082                 }
1083         }
1084
1085         ret = -EBADF;
1086         filp = fget(mqdes);
1087         if (!filp)
1088                 goto out;
1089
1090         inode = filp->f_path.dentry->d_inode;
1091         if (unlikely(filp->f_op != &mqueue_file_operations))
1092                 goto out_fput;
1093         info = MQUEUE_I(inode);
1094
1095         ret = 0;
1096         spin_lock(&info->lock);
1097         if (u_notification == NULL) {
1098                 if (info->notify_owner == task_tgid(current)) {
1099                         remove_notification(info);
1100                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1101                 }
1102         } else if (info->notify_owner != NULL) {
1103                 ret = -EBUSY;
1104         } else {
1105                 switch (notification.sigev_notify) {
1106                 case SIGEV_NONE:
1107                         info->notify.sigev_notify = SIGEV_NONE;
1108                         break;
1109                 case SIGEV_THREAD:
1110                         info->notify_sock = sock;
1111                         info->notify_cookie = nc;
1112                         sock = NULL;
1113                         nc = NULL;
1114                         info->notify.sigev_notify = SIGEV_THREAD;
1115                         break;
1116                 case SIGEV_SIGNAL:
1117                         info->notify.sigev_signo = notification.sigev_signo;
1118                         info->notify.sigev_value = notification.sigev_value;
1119                         info->notify.sigev_notify = SIGEV_SIGNAL;
1120                         break;
1121                 }
1122
1123                 info->notify_owner = get_pid(task_tgid(current));
1124                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1125         }
1126         spin_unlock(&info->lock);
1127 out_fput:
1128         fput(filp);
1129 out:
1130         if (sock) {
1131                 netlink_detachskb(sock, nc);
1132         } else if (nc) {
1133                 dev_kfree_skb(nc);
1134         }
1135         return ret;
1136 }
1137
1138 SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1139                 const struct mq_attr __user *, u_mqstat,
1140                 struct mq_attr __user *, u_omqstat)
1141 {
1142         int ret;
1143         struct mq_attr mqstat, omqstat;
1144         struct file *filp;
1145         struct inode *inode;
1146         struct mqueue_inode_info *info;
1147
1148         if (u_mqstat != NULL) {
1149                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1150                         return -EFAULT;
1151                 if (mqstat.mq_flags & (~O_NONBLOCK))
1152                         return -EINVAL;
1153         }
1154
1155         ret = -EBADF;
1156         filp = fget(mqdes);
1157         if (!filp)
1158                 goto out;
1159
1160         inode = filp->f_path.dentry->d_inode;
1161         if (unlikely(filp->f_op != &mqueue_file_operations))
1162                 goto out_fput;
1163         info = MQUEUE_I(inode);
1164
1165         spin_lock(&info->lock);
1166
1167         omqstat = info->attr;
1168         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1169         if (u_mqstat) {
1170                 audit_mq_getsetattr(mqdes, &mqstat);
1171                 spin_lock(&filp->f_lock);
1172                 if (mqstat.mq_flags & O_NONBLOCK)
1173                         filp->f_flags |= O_NONBLOCK;
1174                 else
1175                         filp->f_flags &= ~O_NONBLOCK;
1176                 spin_unlock(&filp->f_lock);
1177
1178                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1179         }
1180
1181         spin_unlock(&info->lock);
1182
1183         ret = 0;
1184         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1185                                                 sizeof(struct mq_attr)))
1186                 ret = -EFAULT;
1187
1188 out_fput:
1189         fput(filp);
1190 out:
1191         return ret;
1192 }
1193
1194 static const struct inode_operations mqueue_dir_inode_operations = {
1195         .lookup = simple_lookup,
1196         .create = mqueue_create,
1197         .unlink = mqueue_unlink,
1198 };
1199
1200 static const struct file_operations mqueue_file_operations = {
1201         .flush = mqueue_flush_file,
1202         .poll = mqueue_poll_file,
1203         .read = mqueue_read_file,
1204 };
1205
1206 static struct super_operations mqueue_super_ops = {
1207         .alloc_inode = mqueue_alloc_inode,
1208         .destroy_inode = mqueue_destroy_inode,
1209         .statfs = simple_statfs,
1210         .delete_inode = mqueue_delete_inode,
1211         .drop_inode = generic_delete_inode,
1212 };
1213
1214 static struct file_system_type mqueue_fs_type = {
1215         .name = "mqueue",
1216         .get_sb = mqueue_get_sb,
1217         .kill_sb = kill_litter_super,
1218 };
1219
1220 static int msg_max_limit_min = MIN_MSGMAX;
1221 static int msg_max_limit_max = MAX_MSGMAX;
1222
1223 static int msg_maxsize_limit_min = MIN_MSGSIZEMAX;
1224 static int msg_maxsize_limit_max = MAX_MSGSIZEMAX;
1225
1226 static ctl_table mq_sysctls[] = {
1227         {
1228                 .procname       = "queues_max",
1229                 .data           = &init_ipc_ns.mq_queues_max,
1230                 .maxlen         = sizeof(int),
1231                 .mode           = 0644,
1232                 .proc_handler   = &proc_dointvec,
1233         },
1234         {
1235                 .procname       = "msg_max",
1236                 .data           = &init_ipc_ns.mq_msg_max,
1237                 .maxlen         = sizeof(int),
1238                 .mode           = 0644,
1239                 .proc_handler   = &proc_dointvec_minmax,
1240                 .extra1         = &msg_max_limit_min,
1241                 .extra2         = &msg_max_limit_max,
1242         },
1243         {
1244                 .procname       = "msgsize_max",
1245                 .data           = &init_ipc_ns.mq_msgsize_max,
1246                 .maxlen         = sizeof(int),
1247                 .mode           = 0644,
1248                 .proc_handler   = &proc_dointvec_minmax,
1249                 .extra1         = &msg_maxsize_limit_min,
1250                 .extra2         = &msg_maxsize_limit_max,
1251         },
1252         { .ctl_name = 0 }
1253 };
1254
1255 static ctl_table mq_sysctl_dir[] = {
1256         {
1257                 .procname       = "mqueue",
1258                 .mode           = 0555,
1259                 .child          = mq_sysctls,
1260         },
1261         { .ctl_name = 0 }
1262 };
1263
1264 static ctl_table mq_sysctl_root[] = {
1265         {
1266                 .ctl_name       = CTL_FS,
1267                 .procname       = "fs",
1268                 .mode           = 0555,
1269                 .child          = mq_sysctl_dir,
1270         },
1271         { .ctl_name = 0 }
1272 };
1273
1274 static int __init init_mqueue_fs(void)
1275 {
1276         int error;
1277
1278         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1279                                 sizeof(struct mqueue_inode_info), 0,
1280                                 SLAB_HWCACHE_ALIGN, init_once);
1281         if (mqueue_inode_cachep == NULL)
1282                 return -ENOMEM;
1283
1284         /* ignore failues - they are not fatal */
1285         mq_sysctl_table = register_sysctl_table(mq_sysctl_root);
1286
1287         error = register_filesystem(&mqueue_fs_type);
1288         if (error)
1289                 goto out_sysctl;
1290
1291         init_ipc_ns.mq_mnt = kern_mount(&mqueue_fs_type);
1292         if (IS_ERR(init_ipc_ns.mq_mnt)) {
1293                 error = PTR_ERR(init_ipc_ns.mq_mnt);
1294                 goto out_filesystem;
1295         }
1296
1297         /* internal initialization - not common for vfs */
1298         spin_lock_init(&mq_lock);
1299
1300         return 0;
1301
1302 out_filesystem:
1303         unregister_filesystem(&mqueue_fs_type);
1304 out_sysctl:
1305         if (mq_sysctl_table)
1306                 unregister_sysctl_table(mq_sysctl_table);
1307         kmem_cache_destroy(mqueue_inode_cachep);
1308         return error;
1309 }
1310
1311 __initcall(init_mqueue_fs);