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/slab.h>
  36
  37 #include <net/sock.h>
  38 #include "util.h"
  39
  40 #define MQUEUE_MAGIC    0x19800202
  41 #define DIRENT_SIZE     20
  42 #define FILENT_SIZE     80
  43
  44 #define SEND            0
  45 #define RECV            1
  46
  47 #define STATE_NONE      0
  48 #define STATE_PENDING   1
  49 #define STATE_READY     2
  50
  51 struct ext_wait_queue {         /* queue of sleeping tasks */
  52         struct task_struct *task;
  53         struct list_head list;
  54         struct msg_msg *msg;    /* ptr of loaded message */
  55         int state;              /* one of STATE_* values */
  56 };
  57
  58 struct mqueue_inode_info {
  59         spinlock_t lock;
  60         struct inode vfs_inode;
  61         wait_queue_head_t wait_q;
  62
  63         struct msg_msg **messages;
  64         struct mq_attr attr;
  65
  66         struct sigevent notify;
  67         struct pid* notify_owner;
  68         struct user_struct *user;       /* user who created, for accounting */
  69         struct sock *notify_sock;
  70         struct sk_buff *notify_cookie;
  71
  72         /* for tasks waiting for free space and messages, respectively */
  73         struct ext_wait_queue e_wait_q[2];
  74
  75         unsigned long qsize; /* size of queue in memory (sum of all msgs) */
  76 };
  77
  78 static const struct inode_operations mqueue_dir_inode_operations;
  79 static const struct file_operations mqueue_file_operations;
  80 static const struct super_operations mqueue_super_ops;
  81 static void remove_notification(struct mqueue_inode_info *info);
  82
  83 static struct kmem_cache *mqueue_inode_cachep;
  84
  85 static struct ctl_table_header * mq_sysctl_table;
  86
  87 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
  88 {
  89         return container_of(inode, struct mqueue_inode_info, vfs_inode);
  90 }
  91
  92 /*
  93  * This routine should be called with the mq_lock held.
  94  */
  95 static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
  96 {
  97         return get_ipc_ns(inode->i_sb->s_fs_info);
  98 }
  99
 100 static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
 101 {
 102         struct ipc_namespace *ns;
 103
 104         spin_lock(&mq_lock);
 105         ns = __get_ns_from_inode(inode);
 106         spin_unlock(&mq_lock);
 107         return ns;
 108 }
 109
 110 static struct inode *mqueue_get_inode(struct super_block *sb,
 111                 struct ipc_namespace *ipc_ns, int mode,
 112                 struct mq_attr *attr)
 113 {
 114         struct user_struct *u = current_user();
 115         struct inode *inode;
 116         int ret = -ENOMEM;
 117
 118         inode = new_inode(sb);
 119         if (!inode)
 120                 goto err;
 121
 122         inode->i_ino = get_next_ino();
 123         inode->i_mode = mode;
 124         inode->i_uid = current_fsuid();
 125         inode->i_gid = current_fsgid();
 126         inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME;
 127
 128         if (S_ISREG(mode)) {
 129                 struct mqueue_inode_info *info;
 130                 struct task_struct *p = current;
 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 > task_rlimit(p, 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         INIT_LIST_HEAD(&inode->i_dentry);
 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                                 int 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,
 453                     HRTIMER_MODE_ABS, 0, 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                         sig_i.si_pid = task_tgid_nr_ns(current,
 547                                                 ns_of_pid(info->notify_owner));
 548                         sig_i.si_uid = current_uid();
 549
 550                         kill_pid_info(info->notify.sigev_signo,
 551                                       &sig_i, info->notify_owner);
 552                         break;
 553                 case SIGEV_THREAD:
 554                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
 555                         netlink_sendskb(info->notify_sock, info->notify_cookie);
 556                         break;
 557                 }
 558                 /* after notification unregisters process */
 559                 put_pid(info->notify_owner);
 560                 info->notify_owner = NULL;
 561         }
 562         wake_up(&info->wait_q);
 563 }
 564
 565 static int prepare_timeout(const struct timespec __user *u_abs_timeout,
 566                            ktime_t *expires, struct timespec *ts)
 567 {
 568         if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec)))
 569                 return -EFAULT;
 570         if (!timespec_valid(ts))
 571                 return -EINVAL;
 572
 573         *expires = timespec_to_ktime(*ts);
 574         return 0;
 575 }
 576
 577 static void remove_notification(struct mqueue_inode_info *info)
 578 {
 579         if (info->notify_owner != NULL &&
 580             info->notify.sigev_notify == SIGEV_THREAD) {
 581                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
 582                 netlink_sendskb(info->notify_sock, info->notify_cookie);
 583         }
 584         put_pid(info->notify_owner);
 585         info->notify_owner = NULL;
 586 }
 587
 588 static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
 589 {
 590         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
 591                 return 0;
 592         if (capable(CAP_SYS_RESOURCE)) {
 593                 if (attr->mq_maxmsg > HARD_MSGMAX)
 594                         return 0;
 595         } else {
 596                 if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
 597                                 attr->mq_msgsize > ipc_ns->mq_msgsize_max)
 598                         return 0;
 599         }
 600         /* check for overflow */
 601         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
 602                 return 0;
 603         if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize
 604             + sizeof (struct msg_msg *))) <
 605             (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
 606                 return 0;
 607         return 1;
 608 }
 609
 610 /*
 611  * Invoked when creating a new queue via sys_mq_open
 612  */
 613 static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir,
 614                         struct dentry *dentry, int oflag, mode_t mode,
 615                         struct mq_attr *attr)
 616 {
 617         const struct cred *cred = current_cred();
 618         struct file *result;
 619         int ret;
 620
 621         if (attr) {
 622                 if (!mq_attr_ok(ipc_ns, attr)) {
 623                         ret = -EINVAL;
 624                         goto out;
 625                 }
 626                 /* store for use during create */
 627                 dentry->d_fsdata = attr;
 628         }
 629
 630         mode &= ~current_umask();
 631         ret = mnt_want_write(ipc_ns->mq_mnt);
 632         if (ret)
 633                 goto out;
 634         ret = vfs_create(dir->d_inode, dentry, mode, NULL);
 635         dentry->d_fsdata = NULL;
 636         if (ret)
 637                 goto out_drop_write;
 638
 639         result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
 640         /*
 641          * dentry_open() took a persistent mnt_want_write(),
 642          * so we can now drop this one.
 643          */
 644         mnt_drop_write(ipc_ns->mq_mnt);
 645         return result;
 646
 647 out_drop_write:
 648         mnt_drop_write(ipc_ns->mq_mnt);
 649 out:
 650         dput(dentry);
 651         mntput(ipc_ns->mq_mnt);
 652         return ERR_PTR(ret);
 653 }
 654
 655 /* Opens existing queue */
 656 static struct file *do_open(struct ipc_namespace *ipc_ns,
 657                                 struct dentry *dentry, int oflag)
 658 {
 659         int ret;
 660         const struct cred *cred = current_cred();
 661
 662         static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
 663                                                   MAY_READ | MAY_WRITE };
 664
 665         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
 666                 ret = -EINVAL;
 667                 goto err;
 668         }
 669
 670         if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
 671                 ret = -EACCES;
 672                 goto err;
 673         }
 674
 675         return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
 676
 677 err:
 678         dput(dentry);
 679         mntput(ipc_ns->mq_mnt);
 680         return ERR_PTR(ret);
 681 }
 682
 683 SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, mode_t, mode,
 684                 struct mq_attr __user *, u_attr)
 685 {
 686         struct dentry *dentry;
 687         struct file *filp;
 688         char *name;
 689         struct mq_attr attr;
 690         int fd, error;
 691         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
 692
 693         if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
 694                 return -EFAULT;
 695
 696         audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
 697
 698         if (IS_ERR(name = getname(u_name)))
 699                 return PTR_ERR(name);
 700
 701         fd = get_unused_fd_flags(O_CLOEXEC);
 702         if (fd < 0)
 703                 goto out_putname;
 704
 705         mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 706         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
 707         if (IS_ERR(dentry)) {
 708                 error = PTR_ERR(dentry);
 709                 goto out_putfd;
 710         }
 711         mntget(ipc_ns->mq_mnt);
 712
 713         if (oflag & O_CREAT) {
 714                 if (dentry->d_inode) {  /* entry already exists */
 715                         audit_inode(name, dentry);
 716                         if (oflag & O_EXCL) {
 717                                 error = -EEXIST;
 718                                 goto out;
 719                         }
 720                         filp = do_open(ipc_ns, dentry, oflag);
 721                 } else {
 722                         filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root,
 723                                                 dentry, oflag, mode,
 724                                                 u_attr ? &attr : NULL);
 725                 }
 726         } else {
 727                 if (!dentry->d_inode) {
 728                         error = -ENOENT;
 729                         goto out;
 730                 }
 731                 audit_inode(name, dentry);
 732                 filp = do_open(ipc_ns, dentry, oflag);
 733         }
 734
 735         if (IS_ERR(filp)) {
 736                 error = PTR_ERR(filp);
 737                 goto out_putfd;
 738         }
 739
 740         fd_install(fd, filp);
 741         goto out_upsem;
 742
 743 out:
 744         dput(dentry);
 745         mntput(ipc_ns->mq_mnt);
 746 out_putfd:
 747         put_unused_fd(fd);
 748         fd = error;
 749 out_upsem:
 750         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 751 out_putname:
 752         putname(name);
 753         return fd;
 754 }
 755
 756 SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
 757 {
 758         int err;
 759         char *name;
 760         struct dentry *dentry;
 761         struct inode *inode = NULL;
 762         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
 763
 764         name = getname(u_name);
 765         if (IS_ERR(name))
 766                 return PTR_ERR(name);
 767
 768         mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
 769                         I_MUTEX_PARENT);
 770         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
 771         if (IS_ERR(dentry)) {
 772                 err = PTR_ERR(dentry);
 773                 goto out_unlock;
 774         }
 775
 776         if (!dentry->d_inode) {
 777                 err = -ENOENT;
 778                 goto out_err;
 779         }
 780
 781         inode = dentry->d_inode;
 782         if (inode)
 783                 ihold(inode);
 784         err = mnt_want_write(ipc_ns->mq_mnt);
 785         if (err)
 786                 goto out_err;
 787         err = vfs_unlink(dentry->d_parent->d_inode, dentry);
 788         mnt_drop_write(ipc_ns->mq_mnt);
 789 out_err:
 790         dput(dentry);
 791
 792 out_unlock:
 793         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 794         putname(name);
 795         if (inode)
 796                 iput(inode);
 797
 798         return err;
 799 }
 800
 801 /* Pipelined send and receive functions.
 802  *
 803  * If a receiver finds no waiting message, then it registers itself in the
 804  * list of waiting receivers. A sender checks that list before adding the new
 805  * message into the message array. If there is a waiting receiver, then it
 806  * bypasses the message array and directly hands the message over to the
 807  * receiver.
 808  * The receiver accepts the message and returns without grabbing the queue
 809  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
 810  * are necessary. The same algorithm is used for sysv semaphores, see
 811  * ipc/sem.c for more details.
 812  *
 813  * The same algorithm is used for senders.
 814  */
 815
 816 /* pipelined_send() - send a message directly to the task waiting in
 817  * sys_mq_timedreceive() (without inserting message into a queue).
 818  */
 819 static inline void pipelined_send(struct mqueue_inode_info *info,
 820                                   struct msg_msg *message,
 821                                   struct ext_wait_queue *receiver)
 822 {
 823         receiver->msg = message;
 824         list_del(&receiver->list);
 825         receiver->state = STATE_PENDING;
 826         wake_up_process(receiver->task);
 827         smp_wmb();
 828         receiver->state = STATE_READY;
 829 }
 830
 831 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
 832  * gets its message and put to the queue (we have one free place for sure). */
 833 static inline void pipelined_receive(struct mqueue_inode_info *info)
 834 {
 835         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
 836
 837         if (!sender) {
 838                 /* for poll */
 839                 wake_up_interruptible(&info->wait_q);
 840                 return;
 841         }
 842         msg_insert(sender->msg, info);
 843         list_del(&sender->list);
 844         sender->state = STATE_PENDING;
 845         wake_up_process(sender->task);
 846         smp_wmb();
 847         sender->state = STATE_READY;
 848 }
 849
 850 SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
 851                 size_t, msg_len, unsigned int, msg_prio,
 852                 const struct timespec __user *, u_abs_timeout)
 853 {
 854         struct file *filp;
 855         struct inode *inode;
 856         struct ext_wait_queue wait;
 857         struct ext_wait_queue *receiver;
 858         struct msg_msg *msg_ptr;
 859         struct mqueue_inode_info *info;
 860         ktime_t expires, *timeout = NULL;
 861         struct timespec ts;
 862         int ret;
 863
 864         if (u_abs_timeout) {
 865                 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
 866                 if (res)
 867                         return res;
 868                 timeout = &expires;
 869         }
 870
 871         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
 872                 return -EINVAL;
 873
 874         audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL);
 875
 876         filp = fget(mqdes);
 877         if (unlikely(!filp)) {
 878                 ret = -EBADF;
 879                 goto out;
 880         }
 881
 882         inode = filp->f_path.dentry->d_inode;
 883         if (unlikely(filp->f_op != &mqueue_file_operations)) {
 884                 ret = -EBADF;
 885                 goto out_fput;
 886         }
 887         info = MQUEUE_I(inode);
 888         audit_inode(NULL, filp->f_path.dentry);
 889
 890         if (unlikely(!(filp->f_mode & FMODE_WRITE))) {
 891                 ret = -EBADF;
 892                 goto out_fput;
 893         }
 894
 895         if (unlikely(msg_len > info->attr.mq_msgsize)) {
 896                 ret = -EMSGSIZE;
 897                 goto out_fput;
 898         }
 899
 900         /* First try to allocate memory, before doing anything with
 901          * existing queues. */
 902         msg_ptr = load_msg(u_msg_ptr, msg_len);
 903         if (IS_ERR(msg_ptr)) {
 904                 ret = PTR_ERR(msg_ptr);
 905                 goto out_fput;
 906         }
 907         msg_ptr->m_ts = msg_len;
 908         msg_ptr->m_type = msg_prio;
 909
 910         spin_lock(&info->lock);
 911
 912         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
 913                 if (filp->f_flags & O_NONBLOCK) {
 914                         spin_unlock(&info->lock);
 915                         ret = -EAGAIN;
 916                 } else {
 917                         wait.task = current;
 918                         wait.msg = (void *) msg_ptr;
 919                         wait.state = STATE_NONE;
 920                         ret = wq_sleep(info, SEND, timeout, &wait);
 921                 }
 922                 if (ret < 0)
 923                         free_msg(msg_ptr);
 924         } else {
 925                 receiver = wq_get_first_waiter(info, RECV);
 926                 if (receiver) {
 927                         pipelined_send(info, msg_ptr, receiver);
 928                 } else {
 929                         /* adds message to the queue */
 930                         msg_insert(msg_ptr, info);
 931                         __do_notify(info);
 932                 }
 933                 inode->i_atime = inode->i_mtime = inode->i_ctime =
 934                                 CURRENT_TIME;
 935                 spin_unlock(&info->lock);
 936                 ret = 0;
 937         }
 938 out_fput:
 939         fput(filp);
 940 out:
 941         return ret;
 942 }
 943
 944 SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
 945                 size_t, msg_len, unsigned int __user *, u_msg_prio,
 946                 const struct timespec __user *, u_abs_timeout)
 947 {
 948         ssize_t ret;
 949         struct msg_msg *msg_ptr;
 950         struct file *filp;
 951         struct inode *inode;
 952         struct mqueue_inode_info *info;
 953         struct ext_wait_queue wait;
 954         ktime_t expires, *timeout = NULL;
 955         struct timespec ts;
 956
 957         if (u_abs_timeout) {
 958                 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
 959                 if (res)
 960                         return res;
 961                 timeout = &expires;
 962         }
 963
 964         audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
 965
 966         filp = fget(mqdes);
 967         if (unlikely(!filp)) {
 968                 ret = -EBADF;
 969                 goto out;
 970         }
 971
 972         inode = filp->f_path.dentry->d_inode;
 973         if (unlikely(filp->f_op != &mqueue_file_operations)) {
 974                 ret = -EBADF;
 975                 goto out_fput;
 976         }
 977         info = MQUEUE_I(inode);
 978         audit_inode(NULL, filp->f_path.dentry);
 979
 980         if (unlikely(!(filp->f_mode & FMODE_READ))) {
 981                 ret = -EBADF;
 982                 goto out_fput;
 983         }
 984
 985         /* checks if buffer is big enough */
 986         if (unlikely(msg_len < info->attr.mq_msgsize)) {
 987                 ret = -EMSGSIZE;
 988                 goto out_fput;
 989         }
 990
 991         spin_lock(&info->lock);
 992         if (info->attr.mq_curmsgs == 0) {
 993                 if (filp->f_flags & O_NONBLOCK) {
 994                         spin_unlock(&info->lock);
 995                         ret = -EAGAIN;
 996                 } else {
 997                         wait.task = current;
 998                         wait.state = STATE_NONE;
 999                         ret = wq_sleep(info, RECV, timeout, &wait);
1000                         msg_ptr = wait.msg;
1001                 }
1002         } else {
1003                 msg_ptr = msg_get(info);
1004
1005                 inode->i_atime = inode->i_mtime = inode->i_ctime =
1006                                 CURRENT_TIME;
1007
1008                 /* There is now free space in queue. */
1009                 pipelined_receive(info);
1010                 spin_unlock(&info->lock);
1011                 ret = 0;
1012         }
1013         if (ret == 0) {
1014                 ret = msg_ptr->m_ts;
1015
1016                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1017                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1018                         ret = -EFAULT;
1019                 }
1020                 free_msg(msg_ptr);
1021         }
1022 out_fput:
1023         fput(filp);
1024 out:
1025         return ret;
1026 }
1027
1028 /*
1029  * Notes: the case when user wants us to deregister (with NULL as pointer)
1030  * and he isn't currently owner of notification, will be silently discarded.
1031  * It isn't explicitly defined in the POSIX.
1032  */
1033 SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1034                 const struct sigevent __user *, u_notification)
1035 {
1036         int ret;
1037         struct file *filp;
1038         struct sock *sock;
1039         struct inode *inode;
1040         struct sigevent notification;
1041         struct mqueue_inode_info *info;
1042         struct sk_buff *nc;
1043
1044         if (u_notification) {
1045                 if (copy_from_user(&notification, u_notification,
1046                                         sizeof(struct sigevent)))
1047                         return -EFAULT;
1048         }
1049
1050         audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1051
1052         nc = NULL;
1053         sock = NULL;
1054         if (u_notification != NULL) {
1055                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1056                              notification.sigev_notify != SIGEV_SIGNAL &&
1057                              notification.sigev_notify != SIGEV_THREAD))
1058                         return -EINVAL;
1059                 if (notification.sigev_notify == SIGEV_SIGNAL &&
1060                         !valid_signal(notification.sigev_signo)) {
1061                         return -EINVAL;
1062                 }
1063                 if (notification.sigev_notify == SIGEV_THREAD) {
1064                         long timeo;
1065
1066                         /* create the notify skb */
1067                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1068                         if (!nc) {
1069                                 ret = -ENOMEM;
1070                                 goto out;
1071                         }
1072                         if (copy_from_user(nc->data,
1073                                         notification.sigev_value.sival_ptr,
1074                                         NOTIFY_COOKIE_LEN)) {
1075                                 ret = -EFAULT;
1076                                 goto out;
1077                         }
1078
1079                         /* TODO: add a header? */
1080                         skb_put(nc, NOTIFY_COOKIE_LEN);
1081                         /* and attach it to the socket */
1082 retry:
1083                         filp = fget(notification.sigev_signo);
1084                         if (!filp) {
1085                                 ret = -EBADF;
1086                                 goto out;
1087                         }
1088                         sock = netlink_getsockbyfilp(filp);
1089                         fput(filp);
1090                         if (IS_ERR(sock)) {
1091                                 ret = PTR_ERR(sock);
1092                                 sock = NULL;
1093                                 goto out;
1094                         }
1095
1096                         timeo = MAX_SCHEDULE_TIMEOUT;
1097                         ret = netlink_attachskb(sock, nc, &timeo, NULL);
1098                         if (ret == 1)
1099                                 goto retry;
1100                         if (ret) {
1101                                 sock = NULL;
1102                                 nc = NULL;
1103                                 goto out;
1104                         }
1105                 }
1106         }
1107
1108         filp = fget(mqdes);
1109         if (!filp) {
1110                 ret = -EBADF;
1111                 goto out;
1112         }
1113
1114         inode = filp->f_path.dentry->d_inode;
1115         if (unlikely(filp->f_op != &mqueue_file_operations)) {
1116                 ret = -EBADF;
1117                 goto out_fput;
1118         }
1119         info = MQUEUE_I(inode);
1120
1121         ret = 0;
1122         spin_lock(&info->lock);
1123         if (u_notification == NULL) {
1124                 if (info->notify_owner == task_tgid(current)) {
1125                         remove_notification(info);
1126                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1127                 }
1128         } else if (info->notify_owner != NULL) {
1129                 ret = -EBUSY;
1130         } else {
1131                 switch (notification.sigev_notify) {
1132                 case SIGEV_NONE:
1133                         info->notify.sigev_notify = SIGEV_NONE;
1134                         break;
1135                 case SIGEV_THREAD:
1136                         info->notify_sock = sock;
1137                         info->notify_cookie = nc;
1138                         sock = NULL;
1139                         nc = NULL;
1140                         info->notify.sigev_notify = SIGEV_THREAD;
1141                         break;
1142                 case SIGEV_SIGNAL:
1143                         info->notify.sigev_signo = notification.sigev_signo;
1144                         info->notify.sigev_value = notification.sigev_value;
1145                         info->notify.sigev_notify = SIGEV_SIGNAL;
1146                         break;
1147                 }
1148
1149                 info->notify_owner = get_pid(task_tgid(current));
1150                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1151         }
1152         spin_unlock(&info->lock);
1153 out_fput:
1154         fput(filp);
1155 out:
1156         if (sock) {
1157                 netlink_detachskb(sock, nc);
1158         } else if (nc) {
1159                 dev_kfree_skb(nc);
1160         }
1161         return ret;
1162 }
1163
1164 SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1165                 const struct mq_attr __user *, u_mqstat,
1166                 struct mq_attr __user *, u_omqstat)
1167 {
1168         int ret;
1169         struct mq_attr mqstat, omqstat;
1170         struct file *filp;
1171         struct inode *inode;
1172         struct mqueue_inode_info *info;
1173
1174         if (u_mqstat != NULL) {
1175                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1176                         return -EFAULT;
1177                 if (mqstat.mq_flags & (~O_NONBLOCK))
1178                         return -EINVAL;
1179         }
1180
1181         filp = fget(mqdes);
1182         if (!filp) {
1183                 ret = -EBADF;
1184                 goto out;
1185         }
1186
1187         inode = filp->f_path.dentry->d_inode;
1188         if (unlikely(filp->f_op != &mqueue_file_operations)) {
1189                 ret = -EBADF;
1190                 goto out_fput;
1191         }
1192         info = MQUEUE_I(inode);
1193
1194         spin_lock(&info->lock);
1195
1196         omqstat = info->attr;
1197         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1198         if (u_mqstat) {
1199                 audit_mq_getsetattr(mqdes, &mqstat);
1200                 spin_lock(&filp->f_lock);
1201                 if (mqstat.mq_flags & O_NONBLOCK)
1202                         filp->f_flags |= O_NONBLOCK;
1203                 else
1204                         filp->f_flags &= ~O_NONBLOCK;
1205                 spin_unlock(&filp->f_lock);
1206
1207                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1208         }
1209
1210         spin_unlock(&info->lock);
1211
1212         ret = 0;
1213         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1214                                                 sizeof(struct mq_attr)))
1215                 ret = -EFAULT;
1216
1217 out_fput:
1218         fput(filp);
1219 out:
1220         return ret;
1221 }
1222
1223 static const struct inode_operations mqueue_dir_inode_operations = {
1224         .lookup = simple_lookup,
1225         .create = mqueue_create,
1226         .unlink = mqueue_unlink,
1227 };
1228
1229 static const struct file_operations mqueue_file_operations = {
1230         .flush = mqueue_flush_file,
1231         .poll = mqueue_poll_file,
1232         .read = mqueue_read_file,
1233         .llseek = default_llseek,
1234 };
1235
1236 static const struct super_operations mqueue_super_ops = {
1237         .alloc_inode = mqueue_alloc_inode,
1238         .destroy_inode = mqueue_destroy_inode,
1239         .evict_inode = mqueue_evict_inode,
1240         .statfs = simple_statfs,
1241 };
1242
1243 static struct file_system_type mqueue_fs_type = {
1244         .name = "mqueue",
1245         .mount = mqueue_mount,
1246         .kill_sb = kill_litter_super,
1247 };
1248
1249 int mq_init_ns(struct ipc_namespace *ns)
1250 {
1251         ns->mq_queues_count  = 0;
1252         ns->mq_queues_max    = DFLT_QUEUESMAX;
1253         ns->mq_msg_max       = DFLT_MSGMAX;
1254         ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1255
1256         ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1257         if (IS_ERR(ns->mq_mnt)) {
1258                 int err = PTR_ERR(ns->mq_mnt);
1259                 ns->mq_mnt = NULL;
1260                 return err;
1261         }
1262         return 0;
1263 }
1264
1265 void mq_clear_sbinfo(struct ipc_namespace *ns)
1266 {
1267         ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1268 }
1269
1270 void mq_put_mnt(struct ipc_namespace *ns)
1271 {
1272         mntput(ns->mq_mnt);
1273 }
1274
1275 static int __init init_mqueue_fs(void)
1276 {
1277         int error;
1278
1279         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1280                                 sizeof(struct mqueue_inode_info), 0,
1281                                 SLAB_HWCACHE_ALIGN, init_once);
1282         if (mqueue_inode_cachep == NULL)
1283                 return -ENOMEM;
1284
1285         /* ignore failures - they are not fatal */
1286         mq_sysctl_table = mq_register_sysctl_table();
1287
1288         error = register_filesystem(&mqueue_fs_type);
1289         if (error)
1290                 goto out_sysctl;
1291
1292         spin_lock_init(&mq_lock);
1293
1294         init_ipc_ns.mq_mnt = kern_mount_data(&mqueue_fs_type, &init_ipc_ns);
1295         if (IS_ERR(init_ipc_ns.mq_mnt)) {
1296                 error = PTR_ERR(init_ipc_ns.mq_mnt);
1297                 goto out_filesystem;
1298         }
1299
1300         return 0;
1301
1302 out_filesystem:
1303         unregister_filesystem(&mqueue_fs_type);
1304 out_sysctl:
1305         if (mq_sysctl_table)
1306                 unregister_sysctl_table(mq_sysctl_table);
1307         kmem_cache_destroy(mqueue_inode_cachep);
1308         return error;
1309 }
1310
1311 __initcall(init_mqueue_fs);