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