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