ipc/mqueue.c

   1 /*
   2  * POSIX message queues filesystem for Linux.
   3  *
   4  * Copyright (C) 2003,2004  Krzysztof Benedyczak    (golbi@mat.uni.torun.pl)
   5  *                          Michal Wronski          (michal.wronski@gmail.com)
   6  *
   7  * Spinlocks:               Mohamed Abbas           (abbas.mohamed@intel.com)
   8  * Lockless receive & send, fd based notify:
   9  *                          Manfred Spraul          (manfred@colorfullife.com)
  10  *
  11  * Audit:                   George Wilson           (ltcgcw@us.ibm.com)
  12  *
  13  * This file is released under the GPL.
  14  */
  15
  16 #include <linux/capability.h>
  17 #include <linux/init.h>
  18 #include <linux/pagemap.h>
  19 #include <linux/file.h>
  20 #include <linux/mount.h>
  21 #include <linux/namei.h>
  22 #include <linux/sysctl.h>
  23 #include <linux/poll.h>
  24 #include <linux/mqueue.h>
  25 #include <linux/msg.h>
  26 #include <linux/skbuff.h>
  27 #include <linux/netlink.h>
  28 #include <linux/syscalls.h>
  29 #include <linux/audit.h>
  30 #include <linux/signal.h>
  31 #include <linux/mutex.h>
  32 #include <linux/nsproxy.h>
  33 #include <linux/pid.h>
  34 #include <linux/ipc_namespace.h>
  35 #include <linux/user_namespace.h>
  36 #include <linux/slab.h>
  37
  38 #include <net/sock.h>
  39 #include "util.h"
  40
  41 #define MQUEUE_MAGIC    0x19800202
  42 #define DIRENT_SIZE     20
  43 #define FILENT_SIZE     80
  44
  45 #define SEND            0
  46 #define RECV            1
  47
  48 #define STATE_NONE      0
  49 #define STATE_PENDING   1
  50 #define STATE_READY     2
  51
  52 struct ext_wait_queue {         /* queue of sleeping tasks */
  53         struct task_struct *task;
  54         struct list_head list;
  55         struct msg_msg *msg;    /* ptr of loaded message */
  56         int state;              /* one of STATE_* values */
  57 };
  58
  59 struct mqueue_inode_info {
  60         spinlock_t lock;
  61         struct inode vfs_inode;
  62         wait_queue_head_t wait_q;
  63
  64         struct msg_msg **messages;
  65         struct mq_attr attr;
  66
  67         struct sigevent notify;
  68         struct pid* notify_owner;
  69         struct user_struct *user;       /* user who created, for accounting */
  70         struct sock *notify_sock;
  71         struct sk_buff *notify_cookie;
  72
  73         /* for tasks waiting for free space and messages, respectively */
  74         struct ext_wait_queue e_wait_q[2];
  75
  76         unsigned long qsize; /* size of queue in memory (sum of all msgs) */
  77 };
  78
  79 static const struct inode_operations mqueue_dir_inode_operations;
  80 static const struct file_operations mqueue_file_operations;
  81 static const struct super_operations mqueue_super_ops;
  82 static void remove_notification(struct mqueue_inode_info *info);
  83
  84 static struct kmem_cache *mqueue_inode_cachep;
  85
  86 static struct ctl_table_header * mq_sysctl_table;
  87
  88 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
  89 {
  90         return container_of(inode, struct mqueue_inode_info, vfs_inode);
  91 }
  92
  93 /*
  94  * This routine should be called with the mq_lock held.
  95  */
  96 static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
  97 {
  98         return get_ipc_ns(inode->i_sb->s_fs_info);
  99 }
 100
 101 static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
 102 {
 103         struct ipc_namespace *ns;
 104
 105         spin_lock(&mq_lock);
 106         ns = __get_ns_from_inode(inode);
 107         spin_unlock(&mq_lock);
 108         return ns;
 109 }
 110
 111 static struct inode *mqueue_get_inode(struct super_block *sb,
 112                 struct ipc_namespace *ipc_ns, umode_t mode,
 113                 struct mq_attr *attr)
 114 {
 115         struct user_struct *u = current_user();
 116         struct inode *inode;
 117         int ret = -ENOMEM;
 118
 119         inode = new_inode(sb);
 120         if (!inode)
 121                 goto err;
 122
 123         inode->i_ino = get_next_ino();
 124         inode->i_mode = mode;
 125         inode->i_uid = current_fsuid();
 126         inode->i_gid = current_fsgid();
 127         inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME;
 128
 129         if (S_ISREG(mode)) {
 130                 struct mqueue_inode_info *info;
 131                 unsigned long mq_bytes, mq_msg_tblsz;
 132
 133                 inode->i_fop = &mqueue_file_operations;
 134                 inode->i_size = FILENT_SIZE;
 135                 /* mqueue specific info */
 136                 info = MQUEUE_I(inode);
 137                 spin_lock_init(&info->lock);
 138                 init_waitqueue_head(&info->wait_q);
 139                 INIT_LIST_HEAD(&info->e_wait_q[0].list);
 140                 INIT_LIST_HEAD(&info->e_wait_q[1].list);
 141                 info->notify_owner = NULL;
 142                 info->qsize = 0;
 143                 info->user = NULL;      /* set when all is ok */
 144                 memset(&info->attr, 0, sizeof(info->attr));
 145                 info->attr.mq_maxmsg = ipc_ns->mq_msg_max;
 146                 info->attr.mq_msgsize = ipc_ns->mq_msgsize_max;
 147                 if (attr) {
 148                         info->attr.mq_maxmsg = attr->mq_maxmsg;
 149                         info->attr.mq_msgsize = attr->mq_msgsize;
 150                 }
 151                 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
 152                 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
 153                 if (!info->messages)
 154                         goto out_inode;
 155
 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 > rlimit(RLIMIT_MSGQUEUE)) {
 162                         spin_unlock(&mq_lock);
 163                         /* mqueue_evict_inode() releases info->messages */
 164                         ret = -EMFILE;
 165                         goto out_inode;
 166                 }
 167                 u->mq_bytes += mq_bytes;
 168                 spin_unlock(&mq_lock);
 169
 170                 /* all is ok */
 171                 info->user = get_uid(u);
 172         } else if (S_ISDIR(mode)) {
 173                 inc_nlink(inode);
 174                 /* Some things misbehave if size == 0 on a directory */
 175                 inode->i_size = 2 * DIRENT_SIZE;
 176                 inode->i_op = &mqueue_dir_inode_operations;
 177                 inode->i_fop = &simple_dir_operations;
 178         }
 179
 180         return inode;
 181 out_inode:
 182         iput(inode);
 183 err:
 184         return ERR_PTR(ret);
 185 }
 186
 187 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
 188 {
 189         struct inode *inode;
 190         struct ipc_namespace *ns = data;
 191         int error;
 192
 193         sb->s_blocksize = PAGE_CACHE_SIZE;
 194         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 195         sb->s_magic = MQUEUE_MAGIC;
 196         sb->s_op = &mqueue_super_ops;
 197
 198         inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO,
 199                                 NULL);
 200         if (IS_ERR(inode)) {
 201                 error = PTR_ERR(inode);
 202                 goto out;
 203         }
 204
 205         sb->s_root = d_alloc_root(inode);
 206         if (!sb->s_root) {
 207                 iput(inode);
 208                 error = -ENOMEM;
 209                 goto out;
 210         }
 211         error = 0;
 212
 213 out:
 214         return error;
 215 }
 216
 217 static struct dentry *mqueue_mount(struct file_system_type *fs_type,
 218                          int flags, const char *dev_name,
 219                          void *data)
 220 {
 221         if (!(flags & MS_KERNMOUNT))
 222                 data = current->nsproxy->ipc_ns;
 223         return mount_ns(fs_type, flags, data, mqueue_fill_super);
 224 }
 225
 226 static void init_once(void *foo)
 227 {
 228         struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
 229
 230         inode_init_once(&p->vfs_inode);
 231 }
 232
 233 static struct inode *mqueue_alloc_inode(struct super_block *sb)
 234 {
 235         struct mqueue_inode_info *ei;
 236
 237         ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
 238         if (!ei)
 239                 return NULL;
 240         return &ei->vfs_inode;
 241 }
 242
 243 static void mqueue_i_callback(struct rcu_head *head)
 244 {
 245         struct inode *inode = container_of(head, struct inode, i_rcu);
 246         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
 247 }
 248
 249 static void mqueue_destroy_inode(struct inode *inode)
 250 {
 251         call_rcu(&inode->i_rcu, mqueue_i_callback);
 252 }
 253
 254 static void mqueue_evict_inode(struct inode *inode)
 255 {
 256         struct mqueue_inode_info *info;
 257         struct user_struct *user;
 258         unsigned long mq_bytes;
 259         int i;
 260         struct ipc_namespace *ipc_ns;
 261
 262         end_writeback(inode);
 263
 264         if (S_ISDIR(inode->i_mode))
 265                 return;
 266
 267         ipc_ns = get_ns_from_inode(inode);
 268         info = MQUEUE_I(inode);
 269         spin_lock(&info->lock);
 270         for (i = 0; i < info->attr.mq_curmsgs; i++)
 271                 free_msg(info->messages[i]);
 272         kfree(info->messages);
 273         spin_unlock(&info->lock);
 274
 275         /* Total amount of bytes accounted for the mqueue */
 276         mq_bytes = info->attr.mq_maxmsg * (sizeof(struct msg_msg *)
 277             + info->attr.mq_msgsize);
 278         user = info->user;
 279         if (user) {
 280                 spin_lock(&mq_lock);
 281                 user->mq_bytes -= mq_bytes;
 282                 /*
 283                  * get_ns_from_inode() ensures that the
 284                  * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
 285                  * to which we now hold a reference, or it is NULL.
 286                  * We can't put it here under mq_lock, though.
 287                  */
 288                 if (ipc_ns)
 289                         ipc_ns->mq_queues_count--;
 290                 spin_unlock(&mq_lock);
 291                 free_uid(user);
 292         }
 293         if (ipc_ns)
 294                 put_ipc_ns(ipc_ns);
 295 }
 296
 297 static int mqueue_create(struct inode *dir, struct dentry *dentry,
 298                                 umode_t mode, struct nameidata *nd)
 299 {
 300         struct inode *inode;
 301         struct mq_attr *attr = dentry->d_fsdata;
 302         int error;
 303         struct ipc_namespace *ipc_ns;
 304
 305         spin_lock(&mq_lock);
 306         ipc_ns = __get_ns_from_inode(dir);
 307         if (!ipc_ns) {
 308                 error = -EACCES;
 309                 goto out_unlock;
 310         }
 311         if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
 312                         !capable(CAP_SYS_RESOURCE)) {
 313                 error = -ENOSPC;
 314                 goto out_unlock;
 315         }
 316         ipc_ns->mq_queues_count++;
 317         spin_unlock(&mq_lock);
 318
 319         inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
 320         if (IS_ERR(inode)) {
 321                 error = PTR_ERR(inode);
 322                 spin_lock(&mq_lock);
 323                 ipc_ns->mq_queues_count--;
 324                 goto out_unlock;
 325         }
 326
 327         put_ipc_ns(ipc_ns);
 328         dir->i_size += DIRENT_SIZE;
 329         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 330
 331         d_instantiate(dentry, inode);
 332         dget(dentry);
 333         return 0;
 334 out_unlock:
 335         spin_unlock(&mq_lock);
 336         if (ipc_ns)
 337                 put_ipc_ns(ipc_ns);
 338         return error;
 339 }
 340
 341 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
 342 {
 343         struct inode *inode = dentry->d_inode;
 344
 345         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 346         dir->i_size -= DIRENT_SIZE;
 347         drop_nlink(inode);
 348         dput(dentry);
 349         return 0;
 350 }
 351
 352 /*
 353 *       This is routine for system read from queue file.
 354 *       To avoid mess with doing here some sort of mq_receive we allow
 355 *       to read only queue size & notification info (the only values
 356 *       that are interesting from user point of view and aren't accessible
 357 *       through std routines)
 358 */
 359 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
 360                                 size_t count, loff_t *off)
 361 {
 362         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 363         char buffer[FILENT_SIZE];
 364         ssize_t ret;
 365
 366         spin_lock(&info->lock);
 367         snprintf(buffer, sizeof(buffer),
 368                         "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
 369                         info->qsize,
 370                         info->notify_owner ? info->notify.sigev_notify : 0,
 371                         (info->notify_owner &&
 372                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
 373                                 info->notify.sigev_signo : 0,
 374                         pid_vnr(info->notify_owner));
 375         spin_unlock(&info->lock);
 376         buffer[sizeof(buffer)-1] = '\0';
 377
 378         ret = simple_read_from_buffer(u_data, count, off, buffer,
 379                                 strlen(buffer));
 380         if (ret <= 0)
 381                 return ret;
 382
 383         filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
 384         return ret;
 385 }
 386
 387 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
 388 {
 389         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 390
 391         spin_lock(&info->lock);
 392         if (task_tgid(current) == info->notify_owner)
 393                 remove_notification(info);
 394
 395         spin_unlock(&info->lock);
 396         return 0;
 397 }
 398
 399 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
 400 {
 401         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 402         int retval = 0;
 403
 404         poll_wait(filp, &info->wait_q, poll_tab);
 405
 406         spin_lock(&info->lock);
 407         if (info->attr.mq_curmsgs)
 408                 retval = POLLIN | POLLRDNORM;
 409
 410         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
 411                 retval |= POLLOUT | POLLWRNORM;
 412         spin_unlock(&info->lock);
 413
 414         return retval;
 415 }
 416
 417 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
 418 static void wq_add(struct mqueue_inode_info *info, int sr,
 419                         struct ext_wait_queue *ewp)
 420 {
 421         struct ext_wait_queue *walk;
 422
 423         ewp->task = current;
 424
 425         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
 426                 if (walk->task->static_prio <= current->static_prio) {
 427                         list_add_tail(&ewp->list, &walk->list);
 428                         return;
 429                 }
 430         }
 431         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
 432 }
 433
 434 /*
 435  * Puts current task to sleep. Caller must hold queue lock. After return
 436  * lock isn't held.
 437  * sr: SEND or RECV
 438  */
 439 static int wq_sleep(struct mqueue_inode_info *info, int sr,
 440                     ktime_t *timeout, struct ext_wait_queue *ewp)
 441 {
 442         int retval;
 443         signed long time;
 444
 445         wq_add(info, sr, ewp);
 446
 447         for (;;) {
 448                 set_current_state(TASK_INTERRUPTIBLE);
 449
 450                 spin_unlock(&info->lock);
 451                 time = schedule_hrtimeout_range_clock(timeout, 0,
 452                         HRTIMER_MODE_ABS, CLOCK_REALTIME);
 453
 454                 while (ewp->state == STATE_PENDING)
 455                         cpu_relax();
 456
 457                 if (ewp->state == STATE_READY) {
 458                         retval = 0;
 459                         goto out;
 460                 }
 461                 spin_lock(&info->lock);
 462                 if (ewp->state == STATE_READY) {
 463                         retval = 0;
 464                         goto out_unlock;
 465                 }
 466                 if (signal_pending(current)) {
 467                         retval = -ERESTARTSYS;
 468                         break;
 469                 }
 470                 if (time == 0) {
 471                         retval = -ETIMEDOUT;
 472                         break;
 473                 }
 474         }
 475         list_del(&ewp->list);
 476 out_unlock:
 477         spin_unlock(&info->lock);
 478 out:
 479         return retval;
 480 }
 481
 482 /*
 483  * Returns waiting task that should be serviced first or NULL if none exists
 484  */
 485 static struct ext_wait_queue *wq_get_first_waiter(
 486                 struct mqueue_inode_info *info, int sr)
 487 {
 488         struct list_head *ptr;
 489
 490         ptr = info->e_wait_q[sr].list.prev;
 491         if (ptr == &info->e_wait_q[sr].list)
 492                 return NULL;
 493         return list_entry(ptr, struct ext_wait_queue, list);
 494 }
 495
 496 /* Auxiliary functions to manipulate messages' list */
 497 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
 498 {
 499         int k;
 500
 501         k = info->attr.mq_curmsgs - 1;
 502         while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
 503                 info->messages[k + 1] = info->messages[k];
 504                 k--;
 505         }
 506         info->attr.mq_curmsgs++;
 507         info->qsize += ptr->m_ts;
 508         info->messages[k + 1] = ptr;
 509 }
 510
 511 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
 512 {
 513         info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
 514         return info->messages[info->attr.mq_curmsgs];
 515 }
 516
 517 static inline void set_cookie(struct sk_buff *skb, char code)
 518 {
 519         ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
 520 }
 521
 522 /*
 523  * The next function is only to split too long sys_mq_timedsend
 524  */
 525 static void __do_notify(struct mqueue_inode_info *info)
 526 {
 527         /* notification
 528          * invoked when there is registered process and there isn't process
 529          * waiting synchronously for message AND state of queue changed from
 530          * empty to not empty. Here we are sure that no one is waiting
 531          * synchronously. */
 532         if (info->notify_owner &&
 533             info->attr.mq_curmsgs == 1) {
 534                 struct siginfo sig_i;
 535                 switch (info->notify.sigev_notify) {
 536                 case SIGEV_NONE:
 537                         break;
 538                 case SIGEV_SIGNAL:
 539                         /* sends signal */
 540
 541                         sig_i.si_signo = info->notify.sigev_signo;
 542                         sig_i.si_errno = 0;
 543                         sig_i.si_code = SI_MESGQ;
 544                         sig_i.si_value = info->notify.sigev_value;
 545                         /* map current pid/uid into info->owner's namespaces */
 546                         rcu_read_lock();
 547                         sig_i.si_pid = task_tgid_nr_ns(current,
 548                                                 ns_of_pid(info->notify_owner));
 549                         sig_i.si_uid = user_ns_map_uid(info->user->user_ns,
 550                                                 current_cred(), current_uid());
 551                         rcu_read_unlock();
 552
 553                         kill_pid_info(info->notify.sigev_signo,
 554                                       &sig_i, info->notify_owner);
 555                         break;
 556                 case SIGEV_THREAD:
 557                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
 558                         netlink_sendskb(info->notify_sock, info->notify_cookie);
 559                         break;
 560                 }
 561                 /* after notification unregisters process */
 562                 put_pid(info->notify_owner);
 563                 info->notify_owner = NULL;
 564         }
 565         wake_up(&info->wait_q);
 566 }
 567
 568 static int prepare_timeout(const struct timespec __user *u_abs_timeout,
 569                            ktime_t *expires, struct timespec *ts)
 570 {
 571         if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec)))
 572                 return -EFAULT;
 573         if (!timespec_valid(ts))
 574                 return -EINVAL;
 575
 576         *expires = timespec_to_ktime(*ts);
 577         return 0;
 578 }
 579
 580 static void remove_notification(struct mqueue_inode_info *info)
 581 {
 582         if (info->notify_owner != NULL &&
 583             info->notify.sigev_notify == SIGEV_THREAD) {
 584                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
 585                 netlink_sendskb(info->notify_sock, info->notify_cookie);
 586         }
 587         put_pid(info->notify_owner);
 588         info->notify_owner = NULL;
 589 }
 590
 591 static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
 592 {
 593         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
 594                 return 0;
 595         if (capable(CAP_SYS_RESOURCE)) {
 596                 if (attr->mq_maxmsg > HARD_MSGMAX)
 597                         return 0;
 598         } else {
 599                 if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
 600                                 attr->mq_msgsize > ipc_ns->mq_msgsize_max)
 601                         return 0;
 602         }
 603         /* check for overflow */
 604         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
 605                 return 0;
 606         if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize
 607             + sizeof (struct msg_msg *))) <
 608             (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
 609                 return 0;
 610         return 1;
 611 }
 612
 613 /*
 614  * Invoked when creating a new queue via sys_mq_open
 615  */
 616 static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir,
 617                         struct dentry *dentry, int oflag, umode_t mode,
 618                         struct mq_attr *attr)
 619 {
 620         const struct cred *cred = current_cred();
 621         struct file *result;
 622         int ret;
 623
 624         if (attr) {
 625                 if (!mq_attr_ok(ipc_ns, attr)) {
 626                         ret = -EINVAL;
 627                         goto out;
 628                 }
 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         int ret;
 663         const struct cred *cred = current_cred();
 664
 665         static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
 666                                                   MAY_READ | MAY_WRITE };
 667
 668         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
 669                 ret = -EINVAL;
 670                 goto err;
 671         }
 672
 673         if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
 674                 ret = -EACCES;
 675                 goto err;
 676         }
 677
 678         return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
 679
 680 err:
 681         dput(dentry);
 682         mntput(ipc_ns->mq_mnt);
 683         return ERR_PTR(ret);
 684 }
 685
 686 SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
 687                 struct mq_attr __user *, u_attr)
 688 {
 689         struct dentry *dentry;
 690         struct file *filp;
 691         char *name;
 692         struct mq_attr attr;
 693         int fd, error;
 694         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
 695
 696         if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
 697                 return -EFAULT;
 698
 699         audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
 700
 701         if (IS_ERR(name = getname(u_name)))
 702                 return PTR_ERR(name);
 703
 704         fd = get_unused_fd_flags(O_CLOEXEC);
 705         if (fd < 0)
 706                 goto out_putname;
 707
 708         mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 709         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
 710         if (IS_ERR(dentry)) {
 711                 error = PTR_ERR(dentry);
 712                 goto out_putfd;
 713         }
 714         mntget(ipc_ns->mq_mnt);
 715
 716         if (oflag & O_CREAT) {
 717                 if (dentry->d_inode) {  /* entry already exists */
 718                         audit_inode(name, dentry);
 719                         if (oflag & O_EXCL) {
 720                                 error = -EEXIST;
 721                                 goto out;
 722                         }
 723                         filp = do_open(ipc_ns, dentry, oflag);
 724                 } else {
 725                         filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root,
 726                                                 dentry, oflag, mode,
 727                                                 u_attr ? &attr : NULL);
 728                 }
 729         } else {
 730                 if (!dentry->d_inode) {
 731                         error = -ENOENT;
 732                         goto out;
 733                 }
 734                 audit_inode(name, dentry);
 735                 filp = do_open(ipc_ns, dentry, oflag);
 736         }
 737
 738         if (IS_ERR(filp)) {
 739                 error = PTR_ERR(filp);
 740                 goto out_putfd;
 741         }
 742
 743         fd_install(fd, filp);
 744         goto out_upsem;
 745
 746 out:
 747         dput(dentry);
 748         mntput(ipc_ns->mq_mnt);
 749 out_putfd:
 750         put_unused_fd(fd);
 751         fd = error;
 752 out_upsem:
 753         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 754 out_putname:
 755         putname(name);
 756         return fd;
 757 }
 758
 759 SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
 760 {
 761         int err;
 762         char *name;
 763         struct dentry *dentry;
 764         struct inode *inode = NULL;
 765         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
 766
 767         name = getname(u_name);
 768         if (IS_ERR(name))
 769                 return PTR_ERR(name);
 770
 771         mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
 772                         I_MUTEX_PARENT);
 773         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
 774         if (IS_ERR(dentry)) {
 775                 err = PTR_ERR(dentry);
 776                 goto out_unlock;
 777         }
 778
 779         if (!dentry->d_inode) {
 780                 err = -ENOENT;
 781                 goto out_err;
 782         }
 783
 784         inode = dentry->d_inode;
 785         if (inode)
 786                 ihold(inode);
 787         err = mnt_want_write(ipc_ns->mq_mnt);
 788         if (err)
 789                 goto out_err;
 790         err = vfs_unlink(dentry->d_parent->d_inode, dentry);
 791         mnt_drop_write(ipc_ns->mq_mnt);
 792 out_err:
 793         dput(dentry);
 794
 795 out_unlock:
 796         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 797         putname(name);
 798         if (inode)
 799                 iput(inode);
 800
 801         return err;
 802 }
 803
 804 /* Pipelined send and receive functions.
 805  *
 806  * If a receiver finds no waiting message, then it registers itself in the
 807  * list of waiting receivers. A sender checks that list before adding the new
 808  * message into the message array. If there is a waiting receiver, then it
 809  * bypasses the message array and directly hands the message over to the
 810  * receiver.
 811  * The receiver accepts the message and returns without grabbing the queue
 812  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
 813  * are necessary. The same algorithm is used for sysv semaphores, see
 814  * ipc/sem.c for more details.
 815  *
 816  * The same algorithm is used for senders.
 817  */
 818
 819 /* pipelined_send() - send a message directly to the task waiting in
 820  * sys_mq_timedreceive() (without inserting message into a queue).
 821  */
 822 static inline void pipelined_send(struct mqueue_inode_info *info,
 823                                   struct msg_msg *message,
 824                                   struct ext_wait_queue *receiver)
 825 {
 826         receiver->msg = message;
 827         list_del(&receiver->list);
 828         receiver->state = STATE_PENDING;
 829         wake_up_process(receiver->task);
 830         smp_wmb();
 831         receiver->state = STATE_READY;
 832 }
 833
 834 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
 835  * gets its message and put to the queue (we have one free place for sure). */
 836 static inline void pipelined_receive(struct mqueue_inode_info *info)
 837 {
 838         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
 839
 840         if (!sender) {
 841                 /* for poll */
 842                 wake_up_interruptible(&info->wait_q);
 843                 return;
 844         }
 845         msg_insert(sender->msg, info);
 846         list_del(&sender->list);
 847         sender->state = STATE_PENDING;
 848         wake_up_process(sender->task);
 849         smp_wmb();
 850         sender->state = STATE_READY;
 851 }
 852
 853 SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
 854                 size_t, msg_len, unsigned int, msg_prio,
 855                 const struct timespec __user *, u_abs_timeout)
 856 {
 857         struct file *filp;
 858         struct inode *inode;
 859         struct ext_wait_queue wait;
 860         struct ext_wait_queue *receiver;
 861         struct msg_msg *msg_ptr;
 862         struct mqueue_inode_info *info;
 863         ktime_t expires, *timeout = NULL;
 864         struct timespec ts;
 865         int ret;
 866
 867         if (u_abs_timeout) {
 868                 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
 869                 if (res)
 870                         return res;
 871                 timeout = &expires;
 872         }
 873
 874         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
 875                 return -EINVAL;
 876
 877         audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL);
 878
 879         filp = fget(mqdes);
 880         if (unlikely(!filp)) {
 881                 ret = -EBADF;
 882                 goto out;
 883         }
 884
 885         inode = filp->f_path.dentry->d_inode;
 886         if (unlikely(filp->f_op != &mqueue_file_operations)) {
 887                 ret = -EBADF;
 888                 goto out_fput;
 889         }
 890         info = MQUEUE_I(inode);
 891         audit_inode(NULL, filp->f_path.dentry);
 892
 893         if (unlikely(!(filp->f_mode & FMODE_WRITE))) {
 894                 ret = -EBADF;
 895                 goto out_fput;
 896         }
 897
 898         if (unlikely(msg_len > info->attr.mq_msgsize)) {
 899                 ret = -EMSGSIZE;
 900                 goto out_fput;
 901         }
 902
 903         /* First try to allocate memory, before doing anything with
 904          * existing queues. */
 905         msg_ptr = load_msg(u_msg_ptr, msg_len);
 906         if (IS_ERR(msg_ptr)) {
 907                 ret = PTR_ERR(msg_ptr);
 908                 goto out_fput;
 909         }
 910         msg_ptr->m_ts = msg_len;
 911         msg_ptr->m_type = msg_prio;
 912
 913         spin_lock(&info->lock);
 914
 915         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
 916                 if (filp->f_flags & O_NONBLOCK) {
 917                         spin_unlock(&info->lock);
 918                         ret = -EAGAIN;
 919                 } else {
 920                         wait.task = current;
 921                         wait.msg = (void *) msg_ptr;
 922                         wait.state = STATE_NONE;
 923                         ret = wq_sleep(info, SEND, timeout, &wait);
 924                 }
 925                 if (ret < 0)
 926                         free_msg(msg_ptr);
 927         } else {
 928                 receiver = wq_get_first_waiter(info, RECV);
 929                 if (receiver) {
 930                         pipelined_send(info, msg_ptr, receiver);
 931                 } else {
 932                         /* adds message to the queue */
 933                         msg_insert(msg_ptr, info);
 934                         __do_notify(info);
 935                 }
 936                 inode->i_atime = inode->i_mtime = inode->i_ctime =
 937                                 CURRENT_TIME;
 938                 spin_unlock(&info->lock);
 939                 ret = 0;
 940         }
 941 out_fput:
 942         fput(filp);
 943 out:
 944         return ret;
 945 }
 946
 947 SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
 948                 size_t, msg_len, unsigned int __user *, u_msg_prio,
 949                 const struct timespec __user *, u_abs_timeout)
 950 {
 951         ssize_t ret;
 952         struct msg_msg *msg_ptr;
 953         struct file *filp;
 954         struct inode *inode;
 955         struct mqueue_inode_info *info;
 956         struct ext_wait_queue wait;
 957         ktime_t expires, *timeout = NULL;
 958         struct timespec ts;
 959
 960         if (u_abs_timeout) {
 961                 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
 962                 if (res)
 963                         return res;
 964                 timeout = &expires;
 965         }
 966
 967         audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
 968
 969         filp = fget(mqdes);
 970         if (unlikely(!filp)) {
 971                 ret = -EBADF;
 972                 goto out;
 973         }
 974
 975         inode = filp->f_path.dentry->d_inode;
 976         if (unlikely(filp->f_op != &mqueue_file_operations)) {
 977                 ret = -EBADF;
 978                 goto out_fput;
 979         }
 980         info = MQUEUE_I(inode);
 981         audit_inode(NULL, filp->f_path.dentry);
 982
 983         if (unlikely(!(filp->f_mode & FMODE_READ))) {
 984                 ret = -EBADF;
 985                 goto out_fput;
 986         }
 987
 988         /* checks if buffer is big enough */
 989         if (unlikely(msg_len < info->attr.mq_msgsize)) {
 990                 ret = -EMSGSIZE;
 991                 goto out_fput;
 992         }
 993
 994         spin_lock(&info->lock);
 995         if (info->attr.mq_curmsgs == 0) {
 996                 if (filp->f_flags & O_NONBLOCK) {
 997                         spin_unlock(&info->lock);
 998                         ret = -EAGAIN;
 999                 } else {
1000                         wait.task = current;
1001                         wait.state = STATE_NONE;
1002                         ret = wq_sleep(info, RECV, timeout, &wait);
1003                         msg_ptr = wait.msg;
1004                 }
1005         } else {
1006                 msg_ptr = msg_get(info);
1007
1008                 inode->i_atime = inode->i_mtime = inode->i_ctime =
1009                                 CURRENT_TIME;
1010
1011                 /* There is now free space in queue. */
1012                 pipelined_receive(info);
1013                 spin_unlock(&info->lock);
1014                 ret = 0;
1015         }
1016         if (ret == 0) {
1017                 ret = msg_ptr->m_ts;
1018
1019                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1020                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1021                         ret = -EFAULT;
1022                 }
1023                 free_msg(msg_ptr);
1024         }
1025 out_fput:
1026         fput(filp);
1027 out:
1028         return ret;
1029 }
1030
1031 /*
1032  * Notes: the case when user wants us to deregister (with NULL as pointer)
1033  * and he isn't currently owner of notification, will be silently discarded.
1034  * It isn't explicitly defined in the POSIX.
1035  */
1036 SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1037                 const struct sigevent __user *, u_notification)
1038 {
1039         int ret;
1040         struct file *filp;
1041         struct sock *sock;
1042         struct inode *inode;
1043         struct sigevent notification;
1044         struct mqueue_inode_info *info;
1045         struct sk_buff *nc;
1046
1047         if (u_notification) {
1048                 if (copy_from_user(&notification, u_notification,
1049                                         sizeof(struct sigevent)))
1050                         return -EFAULT;
1051         }
1052
1053         audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1054
1055         nc = NULL;
1056         sock = NULL;
1057         if (u_notification != NULL) {
1058                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1059                              notification.sigev_notify != SIGEV_SIGNAL &&
1060                              notification.sigev_notify != SIGEV_THREAD))
1061                         return -EINVAL;
1062                 if (notification.sigev_notify == SIGEV_SIGNAL &&
1063                         !valid_signal(notification.sigev_signo)) {
1064                         return -EINVAL;
1065                 }
1066                 if (notification.sigev_notify == SIGEV_THREAD) {
1067                         long timeo;
1068
1069                         /* create the notify skb */
1070                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1071                         if (!nc) {
1072                                 ret = -ENOMEM;
1073                                 goto out;
1074                         }
1075                         if (copy_from_user(nc->data,
1076                                         notification.sigev_value.sival_ptr,
1077                                         NOTIFY_COOKIE_LEN)) {
1078                                 ret = -EFAULT;
1079                                 goto out;
1080                         }
1081
1082                         /* TODO: add a header? */
1083                         skb_put(nc, NOTIFY_COOKIE_LEN);
1084                         /* and attach it to the socket */
1085 retry:
1086                         filp = fget(notification.sigev_signo);
1087                         if (!filp) {
1088                                 ret = -EBADF;
1089                                 goto out;
1090                         }
1091                         sock = netlink_getsockbyfilp(filp);
1092                         fput(filp);
1093                         if (IS_ERR(sock)) {
1094                                 ret = PTR_ERR(sock);
1095                                 sock = NULL;
1096                                 goto out;
1097                         }
1098
1099                         timeo = MAX_SCHEDULE_TIMEOUT;
1100                         ret = netlink_attachskb(sock, nc, &timeo, NULL);
1101                         if (ret == 1)
1102                                 goto retry;
1103                         if (ret) {
1104                                 sock = NULL;
1105                                 nc = NULL;
1106                                 goto out;
1107                         }
1108                 }
1109         }
1110
1111         filp = fget(mqdes);
1112         if (!filp) {
1113                 ret = -EBADF;
1114                 goto out;
1115         }
1116
1117         inode = filp->f_path.dentry->d_inode;
1118         if (unlikely(filp->f_op != &mqueue_file_operations)) {
1119                 ret = -EBADF;
1120                 goto out_fput;
1121         }
1122         info = MQUEUE_I(inode);
1123
1124         ret = 0;
1125         spin_lock(&info->lock);
1126         if (u_notification == NULL) {
1127                 if (info->notify_owner == task_tgid(current)) {
1128                         remove_notification(info);
1129                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1130                 }
1131         } else if (info->notify_owner != NULL) {
1132                 ret = -EBUSY;
1133         } else {
1134                 switch (notification.sigev_notify) {
1135                 case SIGEV_NONE:
1136                         info->notify.sigev_notify = SIGEV_NONE;
1137                         break;
1138                 case SIGEV_THREAD:
1139                         info->notify_sock = sock;
1140                         info->notify_cookie = nc;
1141                         sock = NULL;
1142                         nc = NULL;
1143                         info->notify.sigev_notify = SIGEV_THREAD;
1144                         break;
1145                 case SIGEV_SIGNAL:
1146                         info->notify.sigev_signo = notification.sigev_signo;
1147                         info->notify.sigev_value = notification.sigev_value;
1148                         info->notify.sigev_notify = SIGEV_SIGNAL;
1149                         break;
1150                 }
1151
1152                 info->notify_owner = get_pid(task_tgid(current));
1153                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1154         }
1155         spin_unlock(&info->lock);
1156 out_fput:
1157         fput(filp);
1158 out:
1159         if (sock) {
1160                 netlink_detachskb(sock, nc);
1161         } else if (nc) {
1162                 dev_kfree_skb(nc);
1163         }
1164         return ret;
1165 }
1166
1167 SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1168                 const struct mq_attr __user *, u_mqstat,
1169                 struct mq_attr __user *, u_omqstat)
1170 {
1171         int ret;
1172         struct mq_attr mqstat, omqstat;
1173         struct file *filp;
1174         struct inode *inode;
1175         struct mqueue_inode_info *info;
1176
1177         if (u_mqstat != NULL) {
1178                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1179                         return -EFAULT;
1180                 if (mqstat.mq_flags & (~O_NONBLOCK))
1181                         return -EINVAL;
1182         }
1183
1184         filp = fget(mqdes);
1185         if (!filp) {
1186                 ret = -EBADF;
1187                 goto out;
1188         }
1189
1190         inode = filp->f_path.dentry->d_inode;
1191         if (unlikely(filp->f_op != &mqueue_file_operations)) {
1192                 ret = -EBADF;
1193                 goto out_fput;
1194         }
1195         info = MQUEUE_I(inode);
1196
1197         spin_lock(&info->lock);
1198
1199         omqstat = info->attr;
1200         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1201         if (u_mqstat) {
1202                 audit_mq_getsetattr(mqdes, &mqstat);
1203                 spin_lock(&filp->f_lock);
1204                 if (mqstat.mq_flags & O_NONBLOCK)
1205                         filp->f_flags |= O_NONBLOCK;
1206                 else
1207                         filp->f_flags &= ~O_NONBLOCK;
1208                 spin_unlock(&filp->f_lock);
1209
1210                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1211         }
1212
1213         spin_unlock(&info->lock);
1214
1215         ret = 0;
1216         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1217                                                 sizeof(struct mq_attr)))
1218                 ret = -EFAULT;
1219
1220 out_fput:
1221         fput(filp);
1222 out:
1223         return ret;
1224 }
1225
1226 static const struct inode_operations mqueue_dir_inode_operations = {
1227         .lookup = simple_lookup,
1228         .create = mqueue_create,
1229         .unlink = mqueue_unlink,
1230 };
1231
1232 static const struct file_operations mqueue_file_operations = {
1233         .flush = mqueue_flush_file,
1234         .poll = mqueue_poll_file,
1235         .read = mqueue_read_file,
1236         .llseek = default_llseek,
1237 };
1238
1239 static const struct super_operations mqueue_super_ops = {
1240         .alloc_inode = mqueue_alloc_inode,
1241         .destroy_inode = mqueue_destroy_inode,
1242         .evict_inode = mqueue_evict_inode,
1243         .statfs = simple_statfs,
1244 };
1245
1246 static struct file_system_type mqueue_fs_type = {
1247         .name = "mqueue",
1248         .mount = mqueue_mount,
1249         .kill_sb = kill_litter_super,
1250 };
1251
1252 int mq_init_ns(struct ipc_namespace *ns)
1253 {
1254         ns->mq_queues_count  = 0;
1255         ns->mq_queues_max    = DFLT_QUEUESMAX;
1256         ns->mq_msg_max       = DFLT_MSGMAX;
1257         ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1258
1259         ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1260         if (IS_ERR(ns->mq_mnt)) {
1261                 int err = PTR_ERR(ns->mq_mnt);
1262                 ns->mq_mnt = NULL;
1263                 return err;
1264         }
1265         return 0;
1266 }
1267
1268 void mq_clear_sbinfo(struct ipc_namespace *ns)
1269 {
1270         ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1271 }
1272
1273 void mq_put_mnt(struct ipc_namespace *ns)
1274 {
1275         kern_unmount(ns->mq_mnt);
1276 }
1277
1278 static int __init init_mqueue_fs(void)
1279 {
1280         int error;
1281
1282         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1283                                 sizeof(struct mqueue_inode_info), 0,
1284                                 SLAB_HWCACHE_ALIGN, init_once);
1285         if (mqueue_inode_cachep == NULL)
1286                 return -ENOMEM;
1287
1288         /* ignore failures - they are not fatal */
1289         mq_sysctl_table = mq_register_sysctl_table();
1290
1291         error = register_filesystem(&mqueue_fs_type);
1292         if (error)
1293                 goto out_sysctl;
1294
1295         spin_lock_init(&mq_lock);
1296
1297         error = mq_init_ns(&init_ipc_ns);
1298         if (error)
1299                 goto out_filesystem;
1300
1301         return 0;
1302
1303 out_filesystem:
1304         unregister_filesystem(&mqueue_fs_type);
1305 out_sysctl:
1306         if (mq_sysctl_table)
1307                 unregister_sysctl_table(mq_sysctl_table);
1308         kmem_cache_destroy(mqueue_inode_cachep);
1309         return error;
1310 }
1311
1312 __initcall(init_mqueue_fs);