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                 struct task_struct *p = current;
 132                 unsigned long mq_bytes, mq_msg_tblsz;
 133
 134                 inode->i_fop = &mqueue_file_operations;
 135                 inode->i_size = FILENT_SIZE;
 136                 /* mqueue specific info */
 137                 info = MQUEUE_I(inode);
 138                 spin_lock_init(&info->lock);
 139                 init_waitqueue_head(&info->wait_q);
 140                 INIT_LIST_HEAD(&info->e_wait_q[0].list);
 141                 INIT_LIST_HEAD(&info->e_wait_q[1].list);
 142                 info->notify_owner = NULL;
 143                 info->qsize = 0;
 144                 info->user = NULL;      /* set when all is ok */
 145                 memset(&info->attr, 0, sizeof(info->attr));
 146                 info->attr.mq_maxmsg = ipc_ns->mq_msg_max;
 147                 info->attr.mq_msgsize = ipc_ns->mq_msgsize_max;
 148                 if (attr) {
 149                         info->attr.mq_maxmsg = attr->mq_maxmsg;
 150                         info->attr.mq_msgsize = attr->mq_msgsize;
 151                 }
 152                 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
 153                 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
 154                 if (!info->messages)
 155                         goto out_inode;
 156
 157                 mq_bytes = (mq_msg_tblsz +
 158                         (info->attr.mq_maxmsg * info->attr.mq_msgsize));
 159
 160                 spin_lock(&mq_lock);
 161                 if (u->mq_bytes + mq_bytes < u->mq_bytes ||
 162                     u->mq_bytes + mq_bytes > task_rlimit(p, RLIMIT_MSGQUEUE)) {
 163                         spin_unlock(&mq_lock);
 164                         /* mqueue_evict_inode() releases info->messages */
 165                         ret = -EMFILE;
 166                         goto out_inode;
 167                 }
 168                 u->mq_bytes += mq_bytes;
 169                 spin_unlock(&mq_lock);
 170
 171                 /* all is ok */
 172                 info->user = get_uid(u);
 173         } else if (S_ISDIR(mode)) {
 174                 inc_nlink(inode);
 175                 /* Some things misbehave if size == 0 on a directory */
 176                 inode->i_size = 2 * DIRENT_SIZE;
 177                 inode->i_op = &mqueue_dir_inode_operations;
 178                 inode->i_fop = &simple_dir_operations;
 179         }
 180
 181         return inode;
 182 out_inode:
 183         iput(inode);
 184 err:
 185         return ERR_PTR(ret);
 186 }
 187
 188 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
 189 {
 190         struct inode *inode;
 191         struct ipc_namespace *ns = data;
 192         int error;
 193
 194         sb->s_blocksize = PAGE_CACHE_SIZE;
 195         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 196         sb->s_magic = MQUEUE_MAGIC;
 197         sb->s_op = &mqueue_super_ops;
 198
 199         inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO,
 200                                 NULL);
 201         if (IS_ERR(inode)) {
 202                 error = PTR_ERR(inode);
 203                 goto out;
 204         }
 205
 206         sb->s_root = d_alloc_root(inode);
 207         if (!sb->s_root) {
 208                 iput(inode);
 209                 error = -ENOMEM;
 210                 goto out;
 211         }
 212         error = 0;
 213
 214 out:
 215         return error;
 216 }
 217
 218 static struct dentry *mqueue_mount(struct file_system_type *fs_type,
 219                          int flags, const char *dev_name,
 220                          void *data)
 221 {
 222         if (!(flags & MS_KERNMOUNT))
 223                 data = current->nsproxy->ipc_ns;
 224         return mount_ns(fs_type, flags, data, mqueue_fill_super);
 225 }
 226
 227 static void init_once(void *foo)
 228 {
 229         struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
 230
 231         inode_init_once(&p->vfs_inode);
 232 }
 233
 234 static struct inode *mqueue_alloc_inode(struct super_block *sb)
 235 {
 236         struct mqueue_inode_info *ei;
 237
 238         ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
 239         if (!ei)
 240                 return NULL;
 241         return &ei->vfs_inode;
 242 }
 243
 244 static void mqueue_i_callback(struct rcu_head *head)
 245 {
 246         struct inode *inode = container_of(head, struct inode, i_rcu);
 247         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
 248 }
 249
 250 static void mqueue_destroy_inode(struct inode *inode)
 251 {
 252         call_rcu(&inode->i_rcu, mqueue_i_callback);
 253 }
 254
 255 static void mqueue_evict_inode(struct inode *inode)
 256 {
 257         struct mqueue_inode_info *info;
 258         struct user_struct *user;
 259         unsigned long mq_bytes;
 260         int i;
 261         struct ipc_namespace *ipc_ns;
 262
 263         end_writeback(inode);
 264
 265         if (S_ISDIR(inode->i_mode))
 266                 return;
 267
 268         ipc_ns = get_ns_from_inode(inode);
 269         info = MQUEUE_I(inode);
 270         spin_lock(&info->lock);
 271         for (i = 0; i < info->attr.mq_curmsgs; i++)
 272                 free_msg(info->messages[i]);
 273         kfree(info->messages);
 274         spin_unlock(&info->lock);
 275
 276         /* Total amount of bytes accounted for the mqueue */
 277         mq_bytes = info->attr.mq_maxmsg * (sizeof(struct msg_msg *)
 278             + info->attr.mq_msgsize);
 279         user = info->user;
 280         if (user) {
 281                 spin_lock(&mq_lock);
 282                 user->mq_bytes -= mq_bytes;
 283                 /*
 284                  * get_ns_from_inode() ensures that the
 285                  * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
 286                  * to which we now hold a reference, or it is NULL.
 287                  * We can't put it here under mq_lock, though.
 288                  */
 289                 if (ipc_ns)
 290                         ipc_ns->mq_queues_count--;
 291                 spin_unlock(&mq_lock);
 292                 free_uid(user);
 293         }
 294         if (ipc_ns)
 295                 put_ipc_ns(ipc_ns);
 296 }
 297
 298 static int mqueue_create(struct inode *dir, struct dentry *dentry,
 299                                 umode_t mode, struct nameidata *nd)
 300 {
 301         struct inode *inode;
 302         struct mq_attr *attr = dentry->d_fsdata;
 303         int error;
 304         struct ipc_namespace *ipc_ns;
 305
 306         spin_lock(&mq_lock);
 307         ipc_ns = __get_ns_from_inode(dir);
 308         if (!ipc_ns) {
 309                 error = -EACCES;
 310                 goto out_unlock;
 311         }
 312         if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
 313                         !capable(CAP_SYS_RESOURCE)) {
 314                 error = -ENOSPC;
 315                 goto out_unlock;
 316         }
 317         ipc_ns->mq_queues_count++;
 318         spin_unlock(&mq_lock);
 319
 320         inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
 321         if (IS_ERR(inode)) {
 322                 error = PTR_ERR(inode);
 323                 spin_lock(&mq_lock);
 324                 ipc_ns->mq_queues_count--;
 325                 goto out_unlock;
 326         }
 327
 328         put_ipc_ns(ipc_ns);
 329         dir->i_size += DIRENT_SIZE;
 330         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 331
 332         d_instantiate(dentry, inode);
 333         dget(dentry);
 334         return 0;
 335 out_unlock:
 336         spin_unlock(&mq_lock);
 337         if (ipc_ns)
 338                 put_ipc_ns(ipc_ns);
 339         return error;
 340 }
 341
 342 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
 343 {
 344         struct inode *inode = dentry->d_inode;
 345
 346         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 347         dir->i_size -= DIRENT_SIZE;
 348         drop_nlink(inode);
 349         dput(dentry);
 350         return 0;
 351 }
 352
 353 /*
 354 *       This is routine for system read from queue file.
 355 *       To avoid mess with doing here some sort of mq_receive we allow
 356 *       to read only queue size & notification info (the only values
 357 *       that are interesting from user point of view and aren't accessible
 358 *       through std routines)
 359 */
 360 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
 361                                 size_t count, loff_t *off)
 362 {
 363         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 364         char buffer[FILENT_SIZE];
 365         ssize_t ret;
 366
 367         spin_lock(&info->lock);
 368         snprintf(buffer, sizeof(buffer),
 369                         "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
 370                         info->qsize,
 371                         info->notify_owner ? info->notify.sigev_notify : 0,
 372                         (info->notify_owner &&
 373                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
 374                                 info->notify.sigev_signo : 0,
 375                         pid_vnr(info->notify_owner));
 376         spin_unlock(&info->lock);
 377         buffer[sizeof(buffer)-1] = '\0';
 378
 379         ret = simple_read_from_buffer(u_data, count, off, buffer,
 380                                 strlen(buffer));
 381         if (ret <= 0)
 382                 return ret;
 383
 384         filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
 385         return ret;
 386 }
 387
 388 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
 389 {
 390         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 391
 392         spin_lock(&info->lock);
 393         if (task_tgid(current) == info->notify_owner)
 394                 remove_notification(info);
 395
 396         spin_unlock(&info->lock);
 397         return 0;
 398 }
 399
 400 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
 401 {
 402         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 403         int retval = 0;
 404
 405         poll_wait(filp, &info->wait_q, poll_tab);
 406
 407         spin_lock(&info->lock);
 408         if (info->attr.mq_curmsgs)
 409                 retval = POLLIN | POLLRDNORM;
 410
 411         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
 412                 retval |= POLLOUT | POLLWRNORM;
 413         spin_unlock(&info->lock);
 414
 415         return retval;
 416 }
 417
 418 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
 419 static void wq_add(struct mqueue_inode_info *info, int sr,
 420                         struct ext_wait_queue *ewp)
 421 {
 422         struct ext_wait_queue *walk;
 423
 424         ewp->task = current;
 425
 426         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
 427                 if (walk->task->static_prio <= current->static_prio) {
 428                         list_add_tail(&ewp->list, &walk->list);
 429                         return;
 430                 }
 431         }
 432         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
 433 }
 434
 435 /*
 436  * Puts current task to sleep. Caller must hold queue lock. After return
 437  * lock isn't held.
 438  * sr: SEND or RECV
 439  */
 440 static int wq_sleep(struct mqueue_inode_info *info, int sr,
 441                     ktime_t *timeout, struct ext_wait_queue *ewp)
 442 {
 443         int retval;
 444         signed long time;
 445
 446         wq_add(info, sr, ewp);
 447
 448         for (;;) {
 449                 set_current_state(TASK_INTERRUPTIBLE);
 450
 451                 spin_unlock(&info->lock);
 452                 time = schedule_hrtimeout_range_clock(timeout, 0,
 453                         HRTIMER_MODE_ABS, CLOCK_REALTIME);
 454
 455                 while (ewp->state == STATE_PENDING)
 456                         cpu_relax();
 457
 458                 if (ewp->state == STATE_READY) {
 459                         retval = 0;
 460                         goto out;
 461                 }
 462                 spin_lock(&info->lock);
 463                 if (ewp->state == STATE_READY) {
 464                         retval = 0;
 465                         goto out_unlock;
 466                 }
 467                 if (signal_pending(current)) {
 468                         retval = -ERESTARTSYS;
 469                         break;
 470                 }
 471                 if (time == 0) {
 472                         retval = -ETIMEDOUT;
 473                         break;
 474                 }
 475         }
 476         list_del(&ewp->list);
 477 out_unlock:
 478         spin_unlock(&info->lock);
 479 out:
 480         return retval;
 481 }
 482
 483 /*
 484  * Returns waiting task that should be serviced first or NULL if none exists
 485  */
 486 static struct ext_wait_queue *wq_get_first_waiter(
 487                 struct mqueue_inode_info *info, int sr)
 488 {
 489         struct list_head *ptr;
 490
 491         ptr = info->e_wait_q[sr].list.prev;
 492         if (ptr == &info->e_wait_q[sr].list)
 493                 return NULL;
 494         return list_entry(ptr, struct ext_wait_queue, list);
 495 }
 496
 497 /* Auxiliary functions to manipulate messages' list */
 498 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
 499 {
 500         int k;
 501
 502         k = info->attr.mq_curmsgs - 1;
 503         while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
 504                 info->messages[k + 1] = info->messages[k];
 505                 k--;
 506         }
 507         info->attr.mq_curmsgs++;
 508         info->qsize += ptr->m_ts;
 509         info->messages[k + 1] = ptr;
 510 }
 511
 512 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
 513 {
 514         info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
 515         return info->messages[info->attr.mq_curmsgs];
 516 }
 517
 518 static inline void set_cookie(struct sk_buff *skb, char code)
 519 {
 520         ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
 521 }
 522
 523 /*
 524  * The next function is only to split too long sys_mq_timedsend
 525  */
 526 static void __do_notify(struct mqueue_inode_info *info)
 527 {
 528         /* notification
 529          * invoked when there is registered process and there isn't process
 530          * waiting synchronously for message AND state of queue changed from
 531          * empty to not empty. Here we are sure that no one is waiting
 532          * synchronously. */
 533         if (info->notify_owner &&
 534             info->attr.mq_curmsgs == 1) {
 535                 struct siginfo sig_i;
 536                 switch (info->notify.sigev_notify) {
 537                 case SIGEV_NONE:
 538                         break;
 539                 case SIGEV_SIGNAL:
 540                         /* sends signal */
 541
 542                         sig_i.si_signo = info->notify.sigev_signo;
 543                         sig_i.si_errno = 0;
 544                         sig_i.si_code = SI_MESGQ;
 545                         sig_i.si_value = info->notify.sigev_value;
 546                         /* map current pid/uid into info->owner's namespaces */
 547                         rcu_read_lock();
 548                         sig_i.si_pid = task_tgid_nr_ns(current,
 549                                                 ns_of_pid(info->notify_owner));
 550                         sig_i.si_uid = user_ns_map_uid(info->user->user_ns,
 551                                                 current_cred(), current_uid());
 552                         rcu_read_unlock();
 553
 554                         kill_pid_info(info->notify.sigev_signo,
 555                                       &sig_i, info->notify_owner);
 556                         break;
 557                 case SIGEV_THREAD:
 558                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
 559                         netlink_sendskb(info->notify_sock, info->notify_cookie);
 560                         break;
 561                 }
 562                 /* after notification unregisters process */
 563                 put_pid(info->notify_owner);
 564                 info->notify_owner = NULL;
 565         }
 566         wake_up(&info->wait_q);
 567 }
 568
 569 static int prepare_timeout(const struct timespec __user *u_abs_timeout,
 570                            ktime_t *expires, struct timespec *ts)
 571 {
 572         if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec)))
 573                 return -EFAULT;
 574         if (!timespec_valid(ts))
 575                 return -EINVAL;
 576
 577         *expires = timespec_to_ktime(*ts);
 578         return 0;
 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             + 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, umode_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                 if (!mq_attr_ok(ipc_ns, attr)) {
 627                         ret = -EINVAL;
 628                         goto out;
 629                 }
 630                 /* store for use during create */
 631                 dentry->d_fsdata = attr;
 632         }
 633
 634         mode &= ~current_umask();
 635         ret = mnt_want_write(ipc_ns->mq_mnt);
 636         if (ret)
 637                 goto out;
 638         ret = vfs_create(dir->d_inode, dentry, mode, NULL);
 639         dentry->d_fsdata = NULL;
 640         if (ret)
 641                 goto out_drop_write;
 642
 643         result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
 644         /*
 645          * dentry_open() took a persistent mnt_want_write(),
 646          * so we can now drop this one.
 647          */
 648         mnt_drop_write(ipc_ns->mq_mnt);
 649         return result;
 650
 651 out_drop_write:
 652         mnt_drop_write(ipc_ns->mq_mnt);
 653 out:
 654         dput(dentry);
 655         mntput(ipc_ns->mq_mnt);
 656         return ERR_PTR(ret);
 657 }
 658
 659 /* Opens existing queue */
 660 static struct file *do_open(struct ipc_namespace *ipc_ns,
 661                                 struct dentry *dentry, int oflag)
 662 {
 663         int ret;
 664         const struct cred *cred = current_cred();
 665
 666         static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
 667                                                   MAY_READ | MAY_WRITE };
 668
 669         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
 670                 ret = -EINVAL;
 671                 goto err;
 672         }
 673
 674         if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
 675                 ret = -EACCES;
 676                 goto err;
 677         }
 678
 679         return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
 680
 681 err:
 682         dput(dentry);
 683         mntput(ipc_ns->mq_mnt);
 684         return ERR_PTR(ret);
 685 }
 686
 687 SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
 688                 struct mq_attr __user *, u_attr)
 689 {
 690         struct dentry *dentry;
 691         struct file *filp;
 692         char *name;
 693         struct mq_attr attr;
 694         int fd, error;
 695         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
 696
 697         if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
 698                 return -EFAULT;
 699
 700         audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
 701
 702         if (IS_ERR(name = getname(u_name)))
 703                 return PTR_ERR(name);
 704
 705         fd = get_unused_fd_flags(O_CLOEXEC);
 706         if (fd < 0)
 707                 goto out_putname;
 708
 709         mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 710         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
 711         if (IS_ERR(dentry)) {
 712                 error = PTR_ERR(dentry);
 713                 goto out_putfd;
 714         }
 715         mntget(ipc_ns->mq_mnt);
 716
 717         if (oflag & O_CREAT) {
 718                 if (dentry->d_inode) {  /* entry already exists */
 719                         audit_inode(name, dentry);
 720                         if (oflag & O_EXCL) {
 721                                 error = -EEXIST;
 722                                 goto out;
 723                         }
 724                         filp = do_open(ipc_ns, dentry, oflag);
 725                 } else {
 726                         filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root,
 727                                                 dentry, oflag, mode,
 728                                                 u_attr ? &attr : NULL);
 729                 }
 730         } else {
 731                 if (!dentry->d_inode) {
 732                         error = -ENOENT;
 733                         goto out;
 734                 }
 735                 audit_inode(name, dentry);
 736                 filp = do_open(ipc_ns, dentry, oflag);
 737         }
 738
 739         if (IS_ERR(filp)) {
 740                 error = PTR_ERR(filp);
 741                 goto out_putfd;
 742         }
 743
 744         fd_install(fd, filp);
 745         goto out_upsem;
 746
 747 out:
 748         dput(dentry);
 749         mntput(ipc_ns->mq_mnt);
 750 out_putfd:
 751         put_unused_fd(fd);
 752         fd = error;
 753 out_upsem:
 754         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 755 out_putname:
 756         putname(name);
 757         return fd;
 758 }
 759
 760 SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
 761 {
 762         int err;
 763         char *name;
 764         struct dentry *dentry;
 765         struct inode *inode = NULL;
 766         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
 767
 768         name = getname(u_name);
 769         if (IS_ERR(name))
 770                 return PTR_ERR(name);
 771
 772         mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
 773                         I_MUTEX_PARENT);
 774         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
 775         if (IS_ERR(dentry)) {
 776                 err = PTR_ERR(dentry);
 777                 goto out_unlock;
 778         }
 779
 780         if (!dentry->d_inode) {
 781                 err = -ENOENT;
 782                 goto out_err;
 783         }
 784
 785         inode = dentry->d_inode;
 786         if (inode)
 787                 ihold(inode);
 788         err = mnt_want_write(ipc_ns->mq_mnt);
 789         if (err)
 790                 goto out_err;
 791         err = vfs_unlink(dentry->d_parent->d_inode, dentry);
 792         mnt_drop_write(ipc_ns->mq_mnt);
 793 out_err:
 794         dput(dentry);
 795
 796 out_unlock:
 797         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 798         putname(name);
 799         if (inode)
 800                 iput(inode);
 801
 802         return err;
 803 }
 804
 805 /* Pipelined send and receive functions.
 806  *
 807  * If a receiver finds no waiting message, then it registers itself in the
 808  * list of waiting receivers. A sender checks that list before adding the new
 809  * message into the message array. If there is a waiting receiver, then it
 810  * bypasses the message array and directly hands the message over to the
 811  * receiver.
 812  * The receiver accepts the message and returns without grabbing the queue
 813  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
 814  * are necessary. The same algorithm is used for sysv semaphores, see
 815  * ipc/sem.c for more details.
 816  *
 817  * The same algorithm is used for senders.
 818  */
 819
 820 /* pipelined_send() - send a message directly to the task waiting in
 821  * sys_mq_timedreceive() (without inserting message into a queue).
 822  */
 823 static inline void pipelined_send(struct mqueue_inode_info *info,
 824                                   struct msg_msg *message,
 825                                   struct ext_wait_queue *receiver)
 826 {
 827         receiver->msg = message;
 828         list_del(&receiver->list);
 829         receiver->state = STATE_PENDING;
 830         wake_up_process(receiver->task);
 831         smp_wmb();
 832         receiver->state = STATE_READY;
 833 }
 834
 835 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
 836  * gets its message and put to the queue (we have one free place for sure). */
 837 static inline void pipelined_receive(struct mqueue_inode_info *info)
 838 {
 839         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
 840
 841         if (!sender) {
 842                 /* for poll */
 843                 wake_up_interruptible(&info->wait_q);
 844                 return;
 845         }
 846         msg_insert(sender->msg, info);
 847         list_del(&sender->list);
 848         sender->state = STATE_PENDING;
 849         wake_up_process(sender->task);
 850         smp_wmb();
 851         sender->state = STATE_READY;
 852 }
 853
 854 SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
 855                 size_t, msg_len, unsigned int, msg_prio,
 856                 const struct timespec __user *, u_abs_timeout)
 857 {
 858         struct file *filp;
 859         struct inode *inode;
 860         struct ext_wait_queue wait;
 861         struct ext_wait_queue *receiver;
 862         struct msg_msg *msg_ptr;
 863         struct mqueue_inode_info *info;
 864         ktime_t expires, *timeout = NULL;
 865         struct timespec ts;
 866         int ret;
 867
 868         if (u_abs_timeout) {
 869                 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
 870                 if (res)
 871                         return res;
 872                 timeout = &expires;
 873         }
 874
 875         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
 876                 return -EINVAL;
 877
 878         audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL);
 879
 880         filp = fget(mqdes);
 881         if (unlikely(!filp)) {
 882                 ret = -EBADF;
 883                 goto out;
 884         }
 885
 886         inode = filp->f_path.dentry->d_inode;
 887         if (unlikely(filp->f_op != &mqueue_file_operations)) {
 888                 ret = -EBADF;
 889                 goto out_fput;
 890         }
 891         info = MQUEUE_I(inode);
 892         audit_inode(NULL, filp->f_path.dentry);
 893
 894         if (unlikely(!(filp->f_mode & FMODE_WRITE))) {
 895                 ret = -EBADF;
 896                 goto out_fput;
 897         }
 898
 899         if (unlikely(msg_len > info->attr.mq_msgsize)) {
 900                 ret = -EMSGSIZE;
 901                 goto out_fput;
 902         }
 903
 904         /* First try to allocate memory, before doing anything with
 905          * existing queues. */
 906         msg_ptr = load_msg(u_msg_ptr, msg_len);
 907         if (IS_ERR(msg_ptr)) {
 908                 ret = PTR_ERR(msg_ptr);
 909                 goto out_fput;
 910         }
 911         msg_ptr->m_ts = msg_len;
 912         msg_ptr->m_type = msg_prio;
 913
 914         spin_lock(&info->lock);
 915
 916         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
 917                 if (filp->f_flags & O_NONBLOCK) {
 918                         spin_unlock(&info->lock);
 919                         ret = -EAGAIN;
 920                 } else {
 921                         wait.task = current;
 922                         wait.msg = (void *) msg_ptr;
 923                         wait.state = STATE_NONE;
 924                         ret = wq_sleep(info, SEND, timeout, &wait);
 925                 }
 926                 if (ret < 0)
 927                         free_msg(msg_ptr);
 928         } else {
 929                 receiver = wq_get_first_waiter(info, RECV);
 930                 if (receiver) {
 931                         pipelined_send(info, msg_ptr, receiver);
 932                 } else {
 933                         /* adds message to the queue */
 934                         msg_insert(msg_ptr, info);
 935                         __do_notify(info);
 936                 }
 937                 inode->i_atime = inode->i_mtime = inode->i_ctime =
 938                                 CURRENT_TIME;
 939                 spin_unlock(&info->lock);
 940                 ret = 0;
 941         }
 942 out_fput:
 943         fput(filp);
 944 out:
 945         return ret;
 946 }
 947
 948 SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
 949                 size_t, msg_len, unsigned int __user *, u_msg_prio,
 950                 const struct timespec __user *, u_abs_timeout)
 951 {
 952         ssize_t ret;
 953         struct msg_msg *msg_ptr;
 954         struct file *filp;
 955         struct inode *inode;
 956         struct mqueue_inode_info *info;
 957         struct ext_wait_queue wait;
 958         ktime_t expires, *timeout = NULL;
 959         struct timespec ts;
 960
 961         if (u_abs_timeout) {
 962                 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
 963                 if (res)
 964                         return res;
 965                 timeout = &expires;
 966         }
 967
 968         audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
 969
 970         filp = fget(mqdes);
 971         if (unlikely(!filp)) {
 972                 ret = -EBADF;
 973                 goto out;
 974         }
 975
 976         inode = filp->f_path.dentry->d_inode;
 977         if (unlikely(filp->f_op != &mqueue_file_operations)) {
 978                 ret = -EBADF;
 979                 goto out_fput;
 980         }
 981         info = MQUEUE_I(inode);
 982         audit_inode(NULL, filp->f_path.dentry);
 983
 984         if (unlikely(!(filp->f_mode & FMODE_READ))) {
 985                 ret = -EBADF;
 986                 goto out_fput;
 987         }
 988
 989         /* checks if buffer is big enough */
 990         if (unlikely(msg_len < info->attr.mq_msgsize)) {
 991                 ret = -EMSGSIZE;
 992                 goto out_fput;
 993         }
 994
 995         spin_lock(&info->lock);
 996         if (info->attr.mq_curmsgs == 0) {
 997                 if (filp->f_flags & O_NONBLOCK) {
 998                         spin_unlock(&info->lock);
 999                         ret = -EAGAIN;
1000                 } else {
1001                         wait.task = current;
1002                         wait.state = STATE_NONE;
1003                         ret = wq_sleep(info, RECV, timeout, &wait);
1004                         msg_ptr = wait.msg;
1005                 }
1006         } else {
1007                 msg_ptr = msg_get(info);
1008
1009                 inode->i_atime = inode->i_mtime = inode->i_ctime =
1010                                 CURRENT_TIME;
1011
1012                 /* There is now free space in queue. */
1013                 pipelined_receive(info);
1014                 spin_unlock(&info->lock);
1015                 ret = 0;
1016         }
1017         if (ret == 0) {
1018                 ret = msg_ptr->m_ts;
1019
1020                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1021                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1022                         ret = -EFAULT;
1023                 }
1024                 free_msg(msg_ptr);
1025         }
1026 out_fput:
1027         fput(filp);
1028 out:
1029         return ret;
1030 }
1031
1032 /*
1033  * Notes: the case when user wants us to deregister (with NULL as pointer)
1034  * and he isn't currently owner of notification, will be silently discarded.
1035  * It isn't explicitly defined in the POSIX.
1036  */
1037 SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1038                 const struct sigevent __user *, u_notification)
1039 {
1040         int ret;
1041         struct file *filp;
1042         struct sock *sock;
1043         struct inode *inode;
1044         struct sigevent notification;
1045         struct mqueue_inode_info *info;
1046         struct sk_buff *nc;
1047
1048         if (u_notification) {
1049                 if (copy_from_user(&notification, u_notification,
1050                                         sizeof(struct sigevent)))
1051                         return -EFAULT;
1052         }
1053
1054         audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1055
1056         nc = NULL;
1057         sock = NULL;
1058         if (u_notification != NULL) {
1059                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1060                              notification.sigev_notify != SIGEV_SIGNAL &&
1061                              notification.sigev_notify != SIGEV_THREAD))
1062                         return -EINVAL;
1063                 if (notification.sigev_notify == SIGEV_SIGNAL &&
1064                         !valid_signal(notification.sigev_signo)) {
1065                         return -EINVAL;
1066                 }
1067                 if (notification.sigev_notify == SIGEV_THREAD) {
1068                         long timeo;
1069
1070                         /* create the notify skb */
1071                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1072                         if (!nc) {
1073                                 ret = -ENOMEM;
1074                                 goto out;
1075                         }
1076                         if (copy_from_user(nc->data,
1077                                         notification.sigev_value.sival_ptr,
1078                                         NOTIFY_COOKIE_LEN)) {
1079                                 ret = -EFAULT;
1080                                 goto out;
1081                         }
1082
1083                         /* TODO: add a header? */
1084                         skb_put(nc, NOTIFY_COOKIE_LEN);
1085                         /* and attach it to the socket */
1086 retry:
1087                         filp = fget(notification.sigev_signo);
1088                         if (!filp) {
1089                                 ret = -EBADF;
1090                                 goto out;
1091                         }
1092                         sock = netlink_getsockbyfilp(filp);
1093                         fput(filp);
1094                         if (IS_ERR(sock)) {
1095                                 ret = PTR_ERR(sock);
1096                                 sock = NULL;
1097                                 goto out;
1098                         }
1099
1100                         timeo = MAX_SCHEDULE_TIMEOUT;
1101                         ret = netlink_attachskb(sock, nc, &timeo, NULL);
1102                         if (ret == 1)
1103                                 goto retry;
1104                         if (ret) {
1105                                 sock = NULL;
1106                                 nc = NULL;
1107                                 goto out;
1108                         }
1109                 }
1110         }
1111
1112         filp = fget(mqdes);
1113         if (!filp) {
1114                 ret = -EBADF;
1115                 goto out;
1116         }
1117
1118         inode = filp->f_path.dentry->d_inode;
1119         if (unlikely(filp->f_op != &mqueue_file_operations)) {
1120                 ret = -EBADF;
1121                 goto out_fput;
1122         }
1123         info = MQUEUE_I(inode);
1124
1125         ret = 0;
1126         spin_lock(&info->lock);
1127         if (u_notification == NULL) {
1128                 if (info->notify_owner == task_tgid(current)) {
1129                         remove_notification(info);
1130                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1131                 }
1132         } else if (info->notify_owner != NULL) {
1133                 ret = -EBUSY;
1134         } else {
1135                 switch (notification.sigev_notify) {
1136                 case SIGEV_NONE:
1137                         info->notify.sigev_notify = SIGEV_NONE;
1138                         break;
1139                 case SIGEV_THREAD:
1140                         info->notify_sock = sock;
1141                         info->notify_cookie = nc;
1142                         sock = NULL;
1143                         nc = NULL;
1144                         info->notify.sigev_notify = SIGEV_THREAD;
1145                         break;
1146                 case SIGEV_SIGNAL:
1147                         info->notify.sigev_signo = notification.sigev_signo;
1148                         info->notify.sigev_value = notification.sigev_value;
1149                         info->notify.sigev_notify = SIGEV_SIGNAL;
1150                         break;
1151                 }
1152
1153                 info->notify_owner = get_pid(task_tgid(current));
1154                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1155         }
1156         spin_unlock(&info->lock);
1157 out_fput:
1158         fput(filp);
1159 out:
1160         if (sock) {
1161                 netlink_detachskb(sock, nc);
1162         } else if (nc) {
1163                 dev_kfree_skb(nc);
1164         }
1165         return ret;
1166 }
1167
1168 SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1169                 const struct mq_attr __user *, u_mqstat,
1170                 struct mq_attr __user *, u_omqstat)
1171 {
1172         int ret;
1173         struct mq_attr mqstat, omqstat;
1174         struct file *filp;
1175         struct inode *inode;
1176         struct mqueue_inode_info *info;
1177
1178         if (u_mqstat != NULL) {
1179                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1180                         return -EFAULT;
1181                 if (mqstat.mq_flags & (~O_NONBLOCK))
1182                         return -EINVAL;
1183         }
1184
1185         filp = fget(mqdes);
1186         if (!filp) {
1187                 ret = -EBADF;
1188                 goto out;
1189         }
1190
1191         inode = filp->f_path.dentry->d_inode;
1192         if (unlikely(filp->f_op != &mqueue_file_operations)) {
1193                 ret = -EBADF;
1194                 goto out_fput;
1195         }
1196         info = MQUEUE_I(inode);
1197
1198         spin_lock(&info->lock);
1199
1200         omqstat = info->attr;
1201         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1202         if (u_mqstat) {
1203                 audit_mq_getsetattr(mqdes, &mqstat);
1204                 spin_lock(&filp->f_lock);
1205                 if (mqstat.mq_flags & O_NONBLOCK)
1206                         filp->f_flags |= O_NONBLOCK;
1207                 else
1208                         filp->f_flags &= ~O_NONBLOCK;
1209                 spin_unlock(&filp->f_lock);
1210
1211                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1212         }
1213
1214         spin_unlock(&info->lock);
1215
1216         ret = 0;
1217         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1218                                                 sizeof(struct mq_attr)))
1219                 ret = -EFAULT;
1220
1221 out_fput:
1222         fput(filp);
1223 out:
1224         return ret;
1225 }
1226
1227 static const struct inode_operations mqueue_dir_inode_operations = {
1228         .lookup = simple_lookup,
1229         .create = mqueue_create,
1230         .unlink = mqueue_unlink,
1231 };
1232
1233 static const struct file_operations mqueue_file_operations = {
1234         .flush = mqueue_flush_file,
1235         .poll = mqueue_poll_file,
1236         .read = mqueue_read_file,
1237         .llseek = default_llseek,
1238 };
1239
1240 static const struct super_operations mqueue_super_ops = {
1241         .alloc_inode = mqueue_alloc_inode,
1242         .destroy_inode = mqueue_destroy_inode,
1243         .evict_inode = mqueue_evict_inode,
1244         .statfs = simple_statfs,
1245 };
1246
1247 static struct file_system_type mqueue_fs_type = {
1248         .name = "mqueue",
1249         .mount = mqueue_mount,
1250         .kill_sb = kill_litter_super,
1251 };
1252
1253 int mq_init_ns(struct ipc_namespace *ns)
1254 {
1255         ns->mq_queues_count  = 0;
1256         ns->mq_queues_max    = DFLT_QUEUESMAX;
1257         ns->mq_msg_max       = DFLT_MSGMAX;
1258         ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1259
1260         ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1261         if (IS_ERR(ns->mq_mnt)) {
1262                 int err = PTR_ERR(ns->mq_mnt);
1263                 ns->mq_mnt = NULL;
1264                 return err;
1265         }
1266         return 0;
1267 }
1268
1269 void mq_clear_sbinfo(struct ipc_namespace *ns)
1270 {
1271         ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1272 }
1273
1274 void mq_put_mnt(struct ipc_namespace *ns)
1275 {
1276         kern_unmount(ns->mq_mnt);
1277 }
1278
1279 static int __init init_mqueue_fs(void)
1280 {
1281         int error;
1282
1283         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1284                                 sizeof(struct mqueue_inode_info), 0,
1285                                 SLAB_HWCACHE_ALIGN, init_once);
1286         if (mqueue_inode_cachep == NULL)
1287                 return -ENOMEM;
1288
1289         /* ignore failures - they are not fatal */
1290         mq_sysctl_table = mq_register_sysctl_table();
1291
1292         error = register_filesystem(&mqueue_fs_type);
1293         if (error)
1294                 goto out_sysctl;
1295
1296         spin_lock_init(&mq_lock);
1297
1298         error = mq_init_ns(&init_ipc_ns);
1299         if (error)
1300                 goto out_filesystem;
1301
1302         return 0;
1303
1304 out_filesystem:
1305         unregister_filesystem(&mqueue_fs_type);
1306 out_sysctl:
1307         if (mq_sysctl_table)
1308                 unregister_sysctl_table(mq_sysctl_table);
1309         kmem_cache_destroy(mqueue_inode_cachep);
1310         return error;
1311 }
1312
1313 __initcall(init_mqueue_fs);