linux/ipc/mqueue.c
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   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
  35#include <net/sock.h>
  36#include "util.h"
  37
  38#define MQUEUE_MAGIC    0x19800202
  39#define DIRENT_SIZE     20
  40#define FILENT_SIZE     80
  41
  42#define SEND            0
  43#define RECV            1
  44
  45#define STATE_NONE      0
  46#define STATE_PENDING   1
  47#define STATE_READY     2
  48
  49/* default values */
  50#define DFLT_QUEUESMAX  256     /* max number of message queues */
  51#define DFLT_MSGMAX     10      /* max number of messages in each queue */
  52#define HARD_MSGMAX     (131072/sizeof(void*))
  53#define DFLT_MSGSIZEMAX 8192    /* max message size */
  54
  55/*
  56 * Define the ranges various user-specified maximum values can
  57 * be set to.
  58 */
  59#define MIN_MSGMAX      1               /* min value for msg_max */
  60#define MAX_MSGMAX      HARD_MSGMAX     /* max value for msg_max */
  61#define MIN_MSGSIZEMAX  128             /* min value for msgsize_max */
  62#define MAX_MSGSIZEMAX  (8192*128)      /* max value for msgsize_max */
  63
  64struct ext_wait_queue {         /* queue of sleeping tasks */
  65        struct task_struct *task;
  66        struct list_head list;
  67        struct msg_msg *msg;    /* ptr of loaded message */
  68        int state;              /* one of STATE_* values */
  69};
  70
  71struct mqueue_inode_info {
  72        spinlock_t lock;
  73        struct inode vfs_inode;
  74        wait_queue_head_t wait_q;
  75
  76        struct msg_msg **messages;
  77        struct mq_attr attr;
  78
  79        struct sigevent notify;
  80        struct pid* notify_owner;
  81        struct user_struct *user;       /* user who created, for accounting */
  82        struct sock *notify_sock;
  83        struct sk_buff *notify_cookie;
  84
  85        /* for tasks waiting for free space and messages, respectively */
  86        struct ext_wait_queue e_wait_q[2];
  87
  88        unsigned long qsize; /* size of queue in memory (sum of all msgs) */
  89};
  90
  91static const struct inode_operations mqueue_dir_inode_operations;
  92static const struct file_operations mqueue_file_operations;
  93static struct super_operations mqueue_super_ops;
  94static void remove_notification(struct mqueue_inode_info *info);
  95
  96static spinlock_t mq_lock;
  97static struct kmem_cache *mqueue_inode_cachep;
  98static struct vfsmount *mqueue_mnt;
  99
 100static unsigned int queues_count;
 101static unsigned int queues_max  = DFLT_QUEUESMAX;
 102static unsigned int msg_max     = DFLT_MSGMAX;
 103static unsigned int msgsize_max = DFLT_MSGSIZEMAX;
 104
 105static struct ctl_table_header * mq_sysctl_table;
 106
 107static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
 108{
 109        return container_of(inode, struct mqueue_inode_info, vfs_inode);
 110}
 111
 112static struct inode *mqueue_get_inode(struct super_block *sb, int mode,
 113                                                        struct mq_attr *attr)
 114{
 115        struct user_struct *u = current_user();
 116        struct inode *inode;
 117
 118        inode = new_inode(sb);
 119        if (inode) {
 120                inode->i_mode = mode;
 121                inode->i_uid = current_fsuid();
 122                inode->i_gid = current_fsgid();
 123                inode->i_mtime = inode->i_ctime = inode->i_atime =
 124                                CURRENT_TIME;
 125
 126                if (S_ISREG(mode)) {
 127                        struct mqueue_inode_info *info;
 128                        struct task_struct *p = current;
 129                        unsigned long mq_bytes, mq_msg_tblsz;
 130
 131                        inode->i_fop = &mqueue_file_operations;
 132                        inode->i_size = FILENT_SIZE;
 133                        /* mqueue specific info */
 134                        info = MQUEUE_I(inode);
 135                        spin_lock_init(&info->lock);
 136                        init_waitqueue_head(&info->wait_q);
 137                        INIT_LIST_HEAD(&info->e_wait_q[0].list);
 138                        INIT_LIST_HEAD(&info->e_wait_q[1].list);
 139                        info->messages = NULL;
 140                        info->notify_owner = NULL;
 141                        info->qsize = 0;
 142                        info->user = NULL;      /* set when all is ok */
 143                        memset(&info->attr, 0, sizeof(info->attr));
 144                        info->attr.mq_maxmsg = msg_max;
 145                        info->attr.mq_msgsize = msgsize_max;
 146                        if (attr) {
 147                                info->attr.mq_maxmsg = attr->mq_maxmsg;
 148                                info->attr.mq_msgsize = attr->mq_msgsize;
 149                        }
 150                        mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
 151                        mq_bytes = (mq_msg_tblsz +
 152                                (info->attr.mq_maxmsg * info->attr.mq_msgsize));
 153
 154                        spin_lock(&mq_lock);
 155                        if (u->mq_bytes + mq_bytes < u->mq_bytes ||
 156                            u->mq_bytes + mq_bytes >
 157                            p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
 158                                spin_unlock(&mq_lock);
 159                                goto out_inode;
 160                        }
 161                        u->mq_bytes += mq_bytes;
 162                        spin_unlock(&mq_lock);
 163
 164                        info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
 165                        if (!info->messages) {
 166                                spin_lock(&mq_lock);
 167                                u->mq_bytes -= mq_bytes;
 168                                spin_unlock(&mq_lock);
 169                                goto out_inode;
 170                        }
 171                        /* all is ok */
 172                        info->user = get_uid(u);
 173                } else if (S_ISDIR(mode)) {
 174                        inc_nlink(inode);
 175                        /* Some things misbehave if size == 0 on a directory */
 176                        inode->i_size = 2 * DIRENT_SIZE;
 177                        inode->i_op = &mqueue_dir_inode_operations;
 178                        inode->i_fop = &simple_dir_operations;
 179                }
 180        }
 181        return inode;
 182out_inode:
 183        make_bad_inode(inode);
 184        iput(inode);
 185        return NULL;
 186}
 187
 188static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
 189{
 190        struct inode *inode;
 191
 192        sb->s_blocksize = PAGE_CACHE_SIZE;
 193        sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 194        sb->s_magic = MQUEUE_MAGIC;
 195        sb->s_op = &mqueue_super_ops;
 196
 197        inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
 198        if (!inode)
 199                return -ENOMEM;
 200
 201        sb->s_root = d_alloc_root(inode);
 202        if (!sb->s_root) {
 203                iput(inode);
 204                return -ENOMEM;
 205        }
 206
 207        return 0;
 208}
 209
 210static int mqueue_get_sb(struct file_system_type *fs_type,
 211                         int flags, const char *dev_name,
 212                         void *data, struct vfsmount *mnt)
 213{
 214        return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt);
 215}
 216
 217static void init_once(void *foo)
 218{
 219        struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
 220
 221        inode_init_once(&p->vfs_inode);
 222}
 223
 224static struct inode *mqueue_alloc_inode(struct super_block *sb)
 225{
 226        struct mqueue_inode_info *ei;
 227
 228        ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
 229        if (!ei)
 230                return NULL;
 231        return &ei->vfs_inode;
 232}
 233
 234static void mqueue_destroy_inode(struct inode *inode)
 235{
 236        kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
 237}
 238
 239static void mqueue_delete_inode(struct inode *inode)
 240{
 241        struct mqueue_inode_info *info;
 242        struct user_struct *user;
 243        unsigned long mq_bytes;
 244        int i;
 245
 246        if (S_ISDIR(inode->i_mode)) {
 247                clear_inode(inode);
 248                return;
 249        }
 250        info = MQUEUE_I(inode);
 251        spin_lock(&info->lock);
 252        for (i = 0; i < info->attr.mq_curmsgs; i++)
 253                free_msg(info->messages[i]);
 254        kfree(info->messages);
 255        spin_unlock(&info->lock);
 256
 257        clear_inode(inode);
 258
 259        mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
 260                   (info->attr.mq_maxmsg * info->attr.mq_msgsize));
 261        user = info->user;
 262        if (user) {
 263                spin_lock(&mq_lock);
 264                user->mq_bytes -= mq_bytes;
 265                queues_count--;
 266                spin_unlock(&mq_lock);
 267                free_uid(user);
 268        }
 269}
 270
 271static int mqueue_create(struct inode *dir, struct dentry *dentry,
 272                                int mode, struct nameidata *nd)
 273{
 274        struct inode *inode;
 275        struct mq_attr *attr = dentry->d_fsdata;
 276        int error;
 277
 278        spin_lock(&mq_lock);
 279        if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
 280                error = -ENOSPC;
 281                goto out_lock;
 282        }
 283        queues_count++;
 284        spin_unlock(&mq_lock);
 285
 286        inode = mqueue_get_inode(dir->i_sb, mode, attr);
 287        if (!inode) {
 288                error = -ENOMEM;
 289                spin_lock(&mq_lock);
 290                queues_count--;
 291                goto out_lock;
 292        }
 293
 294        dir->i_size += DIRENT_SIZE;
 295        dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 296
 297        d_instantiate(dentry, inode);
 298        dget(dentry);
 299        return 0;
 300out_lock:
 301        spin_unlock(&mq_lock);
 302        return error;
 303}
 304
 305static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
 306{
 307        struct inode *inode = dentry->d_inode;
 308
 309        dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 310        dir->i_size -= DIRENT_SIZE;
 311        drop_nlink(inode);
 312        dput(dentry);
 313        return 0;
 314}
 315
 316/*
 317*       This is routine for system read from queue file.
 318*       To avoid mess with doing here some sort of mq_receive we allow
 319*       to read only queue size & notification info (the only values
 320*       that are interesting from user point of view and aren't accessible
 321*       through std routines)
 322*/
 323static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
 324                                size_t count, loff_t *off)
 325{
 326        struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 327        char buffer[FILENT_SIZE];
 328        ssize_t ret;
 329
 330        spin_lock(&info->lock);
 331        snprintf(buffer, sizeof(buffer),
 332                        "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
 333                        info->qsize,
 334                        info->notify_owner ? info->notify.sigev_notify : 0,
 335                        (info->notify_owner &&
 336                         info->notify.sigev_notify == SIGEV_SIGNAL) ?
 337                                info->notify.sigev_signo : 0,
 338                        pid_vnr(info->notify_owner));
 339        spin_unlock(&info->lock);
 340        buffer[sizeof(buffer)-1] = '\0';
 341
 342        ret = simple_read_from_buffer(u_data, count, off, buffer,
 343                                strlen(buffer));
 344        if (ret <= 0)
 345                return ret;
 346
 347        filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
 348        return ret;
 349}
 350
 351static int mqueue_flush_file(struct file *filp, fl_owner_t id)
 352{
 353        struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 354
 355        spin_lock(&info->lock);
 356        if (task_tgid(current) == info->notify_owner)
 357                remove_notification(info);
 358
 359        spin_unlock(&info->lock);
 360        return 0;
 361}
 362
 363static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
 364{
 365        struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 366        int retval = 0;
 367
 368        poll_wait(filp, &info->wait_q, poll_tab);
 369
 370        spin_lock(&info->lock);
 371        if (info->attr.mq_curmsgs)
 372                retval = POLLIN | POLLRDNORM;
 373
 374        if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
 375                retval |= POLLOUT | POLLWRNORM;
 376        spin_unlock(&info->lock);
 377
 378        return retval;
 379}
 380
 381/* Adds current to info->e_wait_q[sr] before element with smaller prio */
 382static void wq_add(struct mqueue_inode_info *info, int sr,
 383                        struct ext_wait_queue *ewp)
 384{
 385        struct ext_wait_queue *walk;
 386
 387        ewp->task = current;
 388
 389        list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
 390                if (walk->task->static_prio <= current->static_prio) {
 391                        list_add_tail(&ewp->list, &walk->list);
 392                        return;
 393                }
 394        }
 395        list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
 396}
 397
 398/*
 399 * Puts current task to sleep. Caller must hold queue lock. After return
 400 * lock isn't held.
 401 * sr: SEND or RECV
 402 */
 403static int wq_sleep(struct mqueue_inode_info *info, int sr,
 404                        long timeout, struct ext_wait_queue *ewp)
 405{
 406        int retval;
 407        signed long time;
 408
 409        wq_add(info, sr, ewp);
 410
 411        for (;;) {
 412                set_current_state(TASK_INTERRUPTIBLE);
 413
 414                spin_unlock(&info->lock);
 415                time = schedule_timeout(timeout);
 416
 417                while (ewp->state == STATE_PENDING)
 418                        cpu_relax();
 419
 420                if (ewp->state == STATE_READY) {
 421                        retval = 0;
 422                        goto out;
 423                }
 424                spin_lock(&info->lock);
 425                if (ewp->state == STATE_READY) {
 426                        retval = 0;
 427                        goto out_unlock;
 428                }
 429                if (signal_pending(current)) {
 430                        retval = -ERESTARTSYS;
 431                        break;
 432                }
 433                if (time == 0) {
 434                        retval = -ETIMEDOUT;
 435                        break;
 436                }
 437        }
 438        list_del(&ewp->list);
 439out_unlock:
 440        spin_unlock(&info->lock);
 441out:
 442        return retval;
 443}
 444
 445/*
 446 * Returns waiting task that should be serviced first or NULL if none exists
 447 */
 448static struct ext_wait_queue *wq_get_first_waiter(
 449                struct mqueue_inode_info *info, int sr)
 450{
 451        struct list_head *ptr;
 452
 453        ptr = info->e_wait_q[sr].list.prev;
 454        if (ptr == &info->e_wait_q[sr].list)
 455                return NULL;
 456        return list_entry(ptr, struct ext_wait_queue, list);
 457}
 458
 459/* Auxiliary functions to manipulate messages' list */
 460static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
 461{
 462        int k;
 463
 464        k = info->attr.mq_curmsgs - 1;
 465        while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
 466                info->messages[k + 1] = info->messages[k];
 467                k--;
 468        }
 469        info->attr.mq_curmsgs++;
 470        info->qsize += ptr->m_ts;
 471        info->messages[k + 1] = ptr;
 472}
 473
 474static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
 475{
 476        info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
 477        return info->messages[info->attr.mq_curmsgs];
 478}
 479
 480static inline void set_cookie(struct sk_buff *skb, char code)
 481{
 482        ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
 483}
 484
 485/*
 486 * The next function is only to split too long sys_mq_timedsend
 487 */
 488static void __do_notify(struct mqueue_inode_info *info)
 489{
 490        /* notification
 491         * invoked when there is registered process and there isn't process
 492         * waiting synchronously for message AND state of queue changed from
 493         * empty to not empty. Here we are sure that no one is waiting
 494         * synchronously. */
 495        if (info->notify_owner &&
 496            info->attr.mq_curmsgs == 1) {
 497                struct siginfo sig_i;
 498                switch (info->notify.sigev_notify) {
 499                case SIGEV_NONE:
 500                        break;
 501                case SIGEV_SIGNAL:
 502                        /* sends signal */
 503
 504                        sig_i.si_signo = info->notify.sigev_signo;
 505                        sig_i.si_errno = 0;
 506                        sig_i.si_code = SI_MESGQ;
 507                        sig_i.si_value = info->notify.sigev_value;
 508                        sig_i.si_pid = task_tgid_nr_ns(current,
 509                                                ns_of_pid(info->notify_owner));
 510                        sig_i.si_uid = current_uid();
 511
 512                        kill_pid_info(info->notify.sigev_signo,
 513                                      &sig_i, info->notify_owner);
 514                        break;
 515                case SIGEV_THREAD:
 516                        set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
 517                        netlink_sendskb(info->notify_sock, info->notify_cookie);
 518                        break;
 519                }
 520                /* after notification unregisters process */
 521                put_pid(info->notify_owner);
 522                info->notify_owner = NULL;
 523        }
 524        wake_up(&info->wait_q);
 525}
 526
 527static long prepare_timeout(struct timespec *p)
 528{
 529        struct timespec nowts;
 530        long timeout;
 531
 532        if (p) {
 533                if (unlikely(p->tv_nsec < 0 || p->tv_sec < 0
 534                        || p->tv_nsec >= NSEC_PER_SEC))
 535                        return -EINVAL;
 536                nowts = CURRENT_TIME;
 537                /* first subtract as jiffies can't be too big */
 538                p->tv_sec -= nowts.tv_sec;
 539                if (p->tv_nsec < nowts.tv_nsec) {
 540                        p->tv_nsec += NSEC_PER_SEC;
 541                        p->tv_sec--;
 542                }
 543                p->tv_nsec -= nowts.tv_nsec;
 544                if (p->tv_sec < 0)
 545                        return 0;
 546
 547                timeout = timespec_to_jiffies(p) + 1;
 548        } else
 549                return MAX_SCHEDULE_TIMEOUT;
 550
 551        return timeout;
 552}
 553
 554static void remove_notification(struct mqueue_inode_info *info)
 555{
 556        if (info->notify_owner != NULL &&
 557            info->notify.sigev_notify == SIGEV_THREAD) {
 558                set_cookie(info->notify_cookie, NOTIFY_REMOVED);
 559                netlink_sendskb(info->notify_sock, info->notify_cookie);
 560        }
 561        put_pid(info->notify_owner);
 562        info->notify_owner = NULL;
 563}
 564
 565static int mq_attr_ok(struct mq_attr *attr)
 566{
 567        if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
 568                return 0;
 569        if (capable(CAP_SYS_RESOURCE)) {
 570                if (attr->mq_maxmsg > HARD_MSGMAX)
 571                        return 0;
 572        } else {
 573                if (attr->mq_maxmsg > msg_max ||
 574                                attr->mq_msgsize > msgsize_max)
 575                        return 0;
 576        }
 577        /* check for overflow */
 578        if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
 579                return 0;
 580        if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
 581            (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
 582            (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
 583                return 0;
 584        return 1;
 585}
 586
 587/*
 588 * Invoked when creating a new queue via sys_mq_open
 589 */
 590static struct file *do_create(struct dentry *dir, struct dentry *dentry,
 591                        int oflag, mode_t mode, struct mq_attr *attr)
 592{
 593        const struct cred *cred = current_cred();
 594        struct file *result;
 595        int ret;
 596
 597        if (attr) {
 598                ret = -EINVAL;
 599                if (!mq_attr_ok(attr))
 600                        goto out;
 601                /* store for use during create */
 602                dentry->d_fsdata = attr;
 603        }
 604
 605        mode &= ~current->fs->umask;
 606        ret = mnt_want_write(mqueue_mnt);
 607        if (ret)
 608                goto out;
 609        ret = vfs_create(dir->d_inode, dentry, mode, NULL);
 610        dentry->d_fsdata = NULL;
 611        if (ret)
 612                goto out_drop_write;
 613
 614        result = dentry_open(dentry, mqueue_mnt, oflag, cred);
 615        /*
 616         * dentry_open() took a persistent mnt_want_write(),
 617         * so we can now drop this one.
 618         */
 619        mnt_drop_write(mqueue_mnt);
 620        return result;
 621
 622out_drop_write:
 623        mnt_drop_write(mqueue_mnt);
 624out:
 625        dput(dentry);
 626        mntput(mqueue_mnt);
 627        return ERR_PTR(ret);
 628}
 629
 630/* Opens existing queue */
 631static struct file *do_open(struct dentry *dentry, int oflag)
 632{
 633        const struct cred *cred = current_cred();
 634
 635        static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
 636                                                  MAY_READ | MAY_WRITE };
 637
 638        if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
 639                dput(dentry);
 640                mntput(mqueue_mnt);
 641                return ERR_PTR(-EINVAL);
 642        }
 643
 644        if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
 645                dput(dentry);
 646                mntput(mqueue_mnt);
 647                return ERR_PTR(-EACCES);
 648        }
 649
 650        return dentry_open(dentry, mqueue_mnt, oflag, cred);
 651}
 652
 653SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, mode_t, mode,
 654                struct mq_attr __user *, u_attr)
 655{
 656        struct dentry *dentry;
 657        struct file *filp;
 658        char *name;
 659        struct mq_attr attr;
 660        int fd, error;
 661
 662        if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
 663                return -EFAULT;
 664
 665        audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
 666
 667        if (IS_ERR(name = getname(u_name)))
 668                return PTR_ERR(name);
 669
 670        fd = get_unused_fd_flags(O_CLOEXEC);
 671        if (fd < 0)
 672                goto out_putname;
 673
 674        mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
 675        dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
 676        if (IS_ERR(dentry)) {
 677                error = PTR_ERR(dentry);
 678                goto out_err;
 679        }
 680        mntget(mqueue_mnt);
 681
 682        if (oflag & O_CREAT) {
 683                if (dentry->d_inode) {  /* entry already exists */
 684                        audit_inode(name, dentry);
 685                        error = -EEXIST;
 686                        if (oflag & O_EXCL)
 687                                goto out;
 688                        filp = do_open(dentry, oflag);
 689                } else {
 690                        filp = do_create(mqueue_mnt->mnt_root, dentry,
 691                                                oflag, mode,
 692                                                u_attr ? &attr : NULL);
 693                }
 694        } else {
 695                error = -ENOENT;
 696                if (!dentry->d_inode)
 697                        goto out;
 698                audit_inode(name, dentry);
 699                filp = do_open(dentry, oflag);
 700        }
 701
 702        if (IS_ERR(filp)) {
 703                error = PTR_ERR(filp);
 704                goto out_putfd;
 705        }
 706
 707        fd_install(fd, filp);
 708        goto out_upsem;
 709
 710out:
 711        dput(dentry);
 712        mntput(mqueue_mnt);
 713out_putfd:
 714        put_unused_fd(fd);
 715out_err:
 716        fd = error;
 717out_upsem:
 718        mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
 719out_putname:
 720        putname(name);
 721        return fd;
 722}
 723
 724SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
 725{
 726        int err;
 727        char *name;
 728        struct dentry *dentry;
 729        struct inode *inode = NULL;
 730
 731        name = getname(u_name);
 732        if (IS_ERR(name))
 733                return PTR_ERR(name);
 734
 735        mutex_lock_nested(&mqueue_mnt->mnt_root->d_inode->i_mutex,
 736                        I_MUTEX_PARENT);
 737        dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
 738        if (IS_ERR(dentry)) {
 739                err = PTR_ERR(dentry);
 740                goto out_unlock;
 741        }
 742
 743        if (!dentry->d_inode) {
 744                err = -ENOENT;
 745                goto out_err;
 746        }
 747
 748        inode = dentry->d_inode;
 749        if (inode)
 750                atomic_inc(&inode->i_count);
 751        err = mnt_want_write(mqueue_mnt);
 752        if (err)
 753                goto out_err;
 754        err = vfs_unlink(dentry->d_parent->d_inode, dentry);
 755        mnt_drop_write(mqueue_mnt);
 756out_err:
 757        dput(dentry);
 758
 759out_unlock:
 760        mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
 761        putname(name);
 762        if (inode)
 763                iput(inode);
 764
 765        return err;
 766}
 767
 768/* Pipelined send and receive functions.
 769 *
 770 * If a receiver finds no waiting message, then it registers itself in the
 771 * list of waiting receivers. A sender checks that list before adding the new
 772 * message into the message array. If there is a waiting receiver, then it
 773 * bypasses the message array and directly hands the message over to the
 774 * receiver.
 775 * The receiver accepts the message and returns without grabbing the queue
 776 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
 777 * are necessary. The same algorithm is used for sysv semaphores, see
 778 * ipc/sem.c for more details.
 779 *
 780 * The same algorithm is used for senders.
 781 */
 782
 783/* pipelined_send() - send a message directly to the task waiting in
 784 * sys_mq_timedreceive() (without inserting message into a queue).
 785 */
 786static inline void pipelined_send(struct mqueue_inode_info *info,
 787                                  struct msg_msg *message,
 788                                  struct ext_wait_queue *receiver)
 789{
 790        receiver->msg = message;
 791        list_del(&receiver->list);
 792        receiver->state = STATE_PENDING;
 793        wake_up_process(receiver->task);
 794        smp_wmb();
 795        receiver->state = STATE_READY;
 796}
 797
 798/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
 799 * gets its message and put to the queue (we have one free place for sure). */
 800static inline void pipelined_receive(struct mqueue_inode_info *info)
 801{
 802        struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
 803
 804        if (!sender) {
 805                /* for poll */
 806                wake_up_interruptible(&info->wait_q);
 807                return;
 808        }
 809        msg_insert(sender->msg, info);
 810        list_del(&sender->list);
 811        sender->state = STATE_PENDING;
 812        wake_up_process(sender->task);
 813        smp_wmb();
 814        sender->state = STATE_READY;
 815}
 816
 817SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
 818                size_t, msg_len, unsigned int, msg_prio,
 819                const struct timespec __user *, u_abs_timeout)
 820{
 821        struct file *filp;
 822        struct inode *inode;
 823        struct ext_wait_queue wait;
 824        struct ext_wait_queue *receiver;
 825        struct msg_msg *msg_ptr;
 826        struct mqueue_inode_info *info;
 827        struct timespec ts, *p = NULL;
 828        long timeout;
 829        int ret;
 830
 831        if (u_abs_timeout) {
 832                if (copy_from_user(&ts, u_abs_timeout, 
 833                                        sizeof(struct timespec)))
 834                        return -EFAULT;
 835                p = &ts;
 836        }
 837
 838        if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
 839                return -EINVAL;
 840
 841        audit_mq_sendrecv(mqdes, msg_len, msg_prio, p);
 842        timeout = prepare_timeout(p);
 843
 844        ret = -EBADF;
 845        filp = fget(mqdes);
 846        if (unlikely(!filp))
 847                goto out;
 848
 849        inode = filp->f_path.dentry->d_inode;
 850        if (unlikely(filp->f_op != &mqueue_file_operations))
 851                goto out_fput;
 852        info = MQUEUE_I(inode);
 853        audit_inode(NULL, filp->f_path.dentry);
 854
 855        if (unlikely(!(filp->f_mode & FMODE_WRITE)))
 856                goto out_fput;
 857
 858        if (unlikely(msg_len > info->attr.mq_msgsize)) {
 859                ret = -EMSGSIZE;
 860                goto out_fput;
 861        }
 862
 863        /* First try to allocate memory, before doing anything with
 864         * existing queues. */
 865        msg_ptr = load_msg(u_msg_ptr, msg_len);
 866        if (IS_ERR(msg_ptr)) {
 867                ret = PTR_ERR(msg_ptr);
 868                goto out_fput;
 869        }
 870        msg_ptr->m_ts = msg_len;
 871        msg_ptr->m_type = msg_prio;
 872
 873        spin_lock(&info->lock);
 874
 875        if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
 876                if (filp->f_flags & O_NONBLOCK) {
 877                        spin_unlock(&info->lock);
 878                        ret = -EAGAIN;
 879                } else if (unlikely(timeout < 0)) {
 880                        spin_unlock(&info->lock);
 881                        ret = timeout;
 882                } else {
 883                        wait.task = current;
 884                        wait.msg = (void *) msg_ptr;
 885                        wait.state = STATE_NONE;
 886                        ret = wq_sleep(info, SEND, timeout, &wait);
 887                }
 888                if (ret < 0)
 889                        free_msg(msg_ptr);
 890        } else {
 891                receiver = wq_get_first_waiter(info, RECV);
 892                if (receiver) {
 893                        pipelined_send(info, msg_ptr, receiver);
 894                } else {
 895                        /* adds message to the queue */
 896                        msg_insert(msg_ptr, info);
 897                        __do_notify(info);
 898                }
 899                inode->i_atime = inode->i_mtime = inode->i_ctime =
 900                                CURRENT_TIME;
 901                spin_unlock(&info->lock);
 902                ret = 0;
 903        }
 904out_fput:
 905        fput(filp);
 906out:
 907        return ret;
 908}
 909
 910SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
 911                size_t, msg_len, unsigned int __user *, u_msg_prio,
 912                const struct timespec __user *, u_abs_timeout)
 913{
 914        long timeout;
 915        ssize_t ret;
 916        struct msg_msg *msg_ptr;
 917        struct file *filp;
 918        struct inode *inode;
 919        struct mqueue_inode_info *info;
 920        struct ext_wait_queue wait;
 921        struct timespec ts, *p = NULL;
 922
 923        if (u_abs_timeout) {
 924                if (copy_from_user(&ts, u_abs_timeout, 
 925                                        sizeof(struct timespec)))
 926                        return -EFAULT;
 927                p = &ts;
 928        }
 929
 930        audit_mq_sendrecv(mqdes, msg_len, 0, p);
 931        timeout = prepare_timeout(p);
 932
 933        ret = -EBADF;
 934        filp = fget(mqdes);
 935        if (unlikely(!filp))
 936                goto out;
 937
 938        inode = filp->f_path.dentry->d_inode;
 939        if (unlikely(filp->f_op != &mqueue_file_operations))
 940                goto out_fput;
 941        info = MQUEUE_I(inode);
 942        audit_inode(NULL, filp->f_path.dentry);
 943
 944        if (unlikely(!(filp->f_mode & FMODE_READ)))
 945                goto out_fput;
 946
 947        /* checks if buffer is big enough */
 948        if (unlikely(msg_len < info->attr.mq_msgsize)) {
 949                ret = -EMSGSIZE;
 950                goto out_fput;
 951        }
 952
 953        spin_lock(&info->lock);
 954        if (info->attr.mq_curmsgs == 0) {
 955                if (filp->f_flags & O_NONBLOCK) {
 956                        spin_unlock(&info->lock);
 957                        ret = -EAGAIN;
 958                        msg_ptr = NULL;
 959                } else if (unlikely(timeout < 0)) {
 960                        spin_unlock(&info->lock);
 961                        ret = timeout;
 962                        msg_ptr = NULL;
 963                } else {
 964                        wait.task = current;
 965                        wait.state = STATE_NONE;
 966                        ret = wq_sleep(info, RECV, timeout, &wait);
 967                        msg_ptr = wait.msg;
 968                }
 969        } else {
 970                msg_ptr = msg_get(info);
 971
 972                inode->i_atime = inode->i_mtime = inode->i_ctime =
 973                                CURRENT_TIME;
 974
 975                /* There is now free space in queue. */
 976                pipelined_receive(info);
 977                spin_unlock(&info->lock);
 978                ret = 0;
 979        }
 980        if (ret == 0) {
 981                ret = msg_ptr->m_ts;
 982
 983                if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
 984                        store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
 985                        ret = -EFAULT;
 986                }
 987                free_msg(msg_ptr);
 988        }
 989out_fput:
 990        fput(filp);
 991out:
 992        return ret;
 993}
 994
 995/*
 996 * Notes: the case when user wants us to deregister (with NULL as pointer)
 997 * and he isn't currently owner of notification, will be silently discarded.
 998 * It isn't explicitly defined in the POSIX.
 999 */
1000SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1001                const struct sigevent __user *, u_notification)
1002{
1003        int ret;
1004        struct file *filp;
1005        struct sock *sock;
1006        struct inode *inode;
1007        struct sigevent notification;
1008        struct mqueue_inode_info *info;
1009        struct sk_buff *nc;
1010
1011        if (u_notification) {
1012                if (copy_from_user(&notification, u_notification,
1013                                        sizeof(struct sigevent)))
1014                        return -EFAULT;
1015        }
1016
1017        audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1018
1019        nc = NULL;
1020        sock = NULL;
1021        if (u_notification != NULL) {
1022                if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1023                             notification.sigev_notify != SIGEV_SIGNAL &&
1024                             notification.sigev_notify != SIGEV_THREAD))
1025                        return -EINVAL;
1026                if (notification.sigev_notify == SIGEV_SIGNAL &&
1027                        !valid_signal(notification.sigev_signo)) {
1028                        return -EINVAL;
1029                }
1030                if (notification.sigev_notify == SIGEV_THREAD) {
1031                        long timeo;
1032
1033                        /* create the notify skb */
1034                        nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1035                        ret = -ENOMEM;
1036                        if (!nc)
1037                                goto out;
1038                        ret = -EFAULT;
1039                        if (copy_from_user(nc->data,
1040                                        notification.sigev_value.sival_ptr,
1041                                        NOTIFY_COOKIE_LEN)) {
1042                                goto out;
1043                        }
1044
1045                        /* TODO: add a header? */
1046                        skb_put(nc, NOTIFY_COOKIE_LEN);
1047                        /* and attach it to the socket */
1048retry:
1049                        filp = fget(notification.sigev_signo);
1050                        ret = -EBADF;
1051                        if (!filp)
1052                                goto out;
1053                        sock = netlink_getsockbyfilp(filp);
1054                        fput(filp);
1055                        if (IS_ERR(sock)) {
1056                                ret = PTR_ERR(sock);
1057                                sock = NULL;
1058                                goto out;
1059                        }
1060
1061                        timeo = MAX_SCHEDULE_TIMEOUT;
1062                        ret = netlink_attachskb(sock, nc, &timeo, NULL);
1063                        if (ret == 1)
1064                                goto retry;
1065                        if (ret) {
1066                                sock = NULL;
1067                                nc = NULL;
1068                                goto out;
1069                        }
1070                }
1071        }
1072
1073        ret = -EBADF;
1074        filp = fget(mqdes);
1075        if (!filp)
1076                goto out;
1077
1078        inode = filp->f_path.dentry->d_inode;
1079        if (unlikely(filp->f_op != &mqueue_file_operations))
1080                goto out_fput;
1081        info = MQUEUE_I(inode);
1082
1083        ret = 0;
1084        spin_lock(&info->lock);
1085        if (u_notification == NULL) {
1086                if (info->notify_owner == task_tgid(current)) {
1087                        remove_notification(info);
1088                        inode->i_atime = inode->i_ctime = CURRENT_TIME;
1089                }
1090        } else if (info->notify_owner != NULL) {
1091                ret = -EBUSY;
1092        } else {
1093                switch (notification.sigev_notify) {
1094                case SIGEV_NONE:
1095                        info->notify.sigev_notify = SIGEV_NONE;
1096                        break;
1097                case SIGEV_THREAD:
1098                        info->notify_sock = sock;
1099                        info->notify_cookie = nc;
1100                        sock = NULL;
1101                        nc = NULL;
1102                        info->notify.sigev_notify = SIGEV_THREAD;
1103                        break;
1104                case SIGEV_SIGNAL:
1105                        info->notify.sigev_signo = notification.sigev_signo;
1106                        info->notify.sigev_value = notification.sigev_value;
1107                        info->notify.sigev_notify = SIGEV_SIGNAL;
1108                        break;
1109                }
1110
1111                info->notify_owner = get_pid(task_tgid(current));
1112                inode->i_atime = inode->i_ctime = CURRENT_TIME;
1113        }
1114        spin_unlock(&info->lock);
1115out_fput:
1116        fput(filp);
1117out:
1118        if (sock) {
1119                netlink_detachskb(sock, nc);
1120        } else if (nc) {
1121                dev_kfree_skb(nc);
1122        }
1123        return ret;
1124}
1125
1126SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1127                const struct mq_attr __user *, u_mqstat,
1128                struct mq_attr __user *, u_omqstat)
1129{
1130        int ret;
1131        struct mq_attr mqstat, omqstat;
1132        struct file *filp;
1133        struct inode *inode;
1134        struct mqueue_inode_info *info;
1135
1136        if (u_mqstat != NULL) {
1137                if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1138                        return -EFAULT;
1139                if (mqstat.mq_flags & (~O_NONBLOCK))
1140                        return -EINVAL;
1141        }
1142
1143        ret = -EBADF;
1144        filp = fget(mqdes);
1145        if (!filp)
1146                goto out;
1147
1148        inode = filp->f_path.dentry->d_inode;
1149        if (unlikely(filp->f_op != &mqueue_file_operations))
1150                goto out_fput;
1151        info = MQUEUE_I(inode);
1152
1153        spin_lock(&info->lock);
1154
1155        omqstat = info->attr;
1156        omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1157        if (u_mqstat) {
1158                audit_mq_getsetattr(mqdes, &mqstat);
1159                if (mqstat.mq_flags & O_NONBLOCK)
1160                        filp->f_flags |= O_NONBLOCK;
1161                else
1162                        filp->f_flags &= ~O_NONBLOCK;
1163
1164                inode->i_atime = inode->i_ctime = CURRENT_TIME;
1165        }
1166
1167        spin_unlock(&info->lock);
1168
1169        ret = 0;
1170        if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1171                                                sizeof(struct mq_attr)))
1172                ret = -EFAULT;
1173
1174out_fput:
1175        fput(filp);
1176out:
1177        return ret;
1178}
1179
1180static const struct inode_operations mqueue_dir_inode_operations = {
1181        .lookup = simple_lookup,
1182        .create = mqueue_create,
1183        .unlink = mqueue_unlink,
1184};
1185
1186static const struct file_operations mqueue_file_operations = {
1187        .flush = mqueue_flush_file,
1188        .poll = mqueue_poll_file,
1189        .read = mqueue_read_file,
1190};
1191
1192static struct super_operations mqueue_super_ops = {
1193        .alloc_inode = mqueue_alloc_inode,
1194        .destroy_inode = mqueue_destroy_inode,
1195        .statfs = simple_statfs,
1196        .delete_inode = mqueue_delete_inode,
1197        .drop_inode = generic_delete_inode,
1198};
1199
1200static struct file_system_type mqueue_fs_type = {
1201        .name = "mqueue",
1202        .get_sb = mqueue_get_sb,
1203        .kill_sb = kill_litter_super,
1204};
1205
1206static int msg_max_limit_min = MIN_MSGMAX;
1207static int msg_max_limit_max = MAX_MSGMAX;
1208
1209static int msg_maxsize_limit_min = MIN_MSGSIZEMAX;
1210static int msg_maxsize_limit_max = MAX_MSGSIZEMAX;
1211
1212static ctl_table mq_sysctls[] = {
1213        {
1214                .procname       = "queues_max",
1215                .data           = &queues_max,
1216                .maxlen         = sizeof(int),
1217                .mode           = 0644,
1218                .proc_handler   = &proc_dointvec,
1219        },
1220        {
1221                .procname       = "msg_max",
1222                .data           = &msg_max,
1223                .maxlen         = sizeof(int),
1224                .mode           = 0644,
1225                .proc_handler   = &proc_dointvec_minmax,
1226                .extra1         = &msg_max_limit_min,
1227                .extra2         = &msg_max_limit_max,
1228        },
1229        {
1230                .procname       = "msgsize_max",
1231                .data           = &msgsize_max,
1232                .maxlen         = sizeof(int),
1233                .mode           = 0644,
1234                .proc_handler   = &proc_dointvec_minmax,
1235                .extra1         = &msg_maxsize_limit_min,
1236                .extra2         = &msg_maxsize_limit_max,
1237        },
1238        { .ctl_name = 0 }
1239};
1240
1241static ctl_table mq_sysctl_dir[] = {
1242        {
1243                .procname       = "mqueue",
1244                .mode           = 0555,
1245                .child          = mq_sysctls,
1246        },
1247        { .ctl_name = 0 }
1248};
1249
1250static ctl_table mq_sysctl_root[] = {
1251        {
1252                .ctl_name       = CTL_FS,
1253                .procname       = "fs",
1254                .mode           = 0555,
1255                .child          = mq_sysctl_dir,
1256        },
1257        { .ctl_name = 0 }
1258};
1259
1260static int __init init_mqueue_fs(void)
1261{
1262        int error;
1263
1264        mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1265                                sizeof(struct mqueue_inode_info), 0,
1266                                SLAB_HWCACHE_ALIGN, init_once);
1267        if (mqueue_inode_cachep == NULL)
1268                return -ENOMEM;
1269
1270        /* ignore failues - they are not fatal */
1271        mq_sysctl_table = register_sysctl_table(mq_sysctl_root);
1272
1273        error = register_filesystem(&mqueue_fs_type);
1274        if (error)
1275                goto out_sysctl;
1276
1277        if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1278                error = PTR_ERR(mqueue_mnt);
1279                goto out_filesystem;
1280        }
1281
1282        /* internal initialization - not common for vfs */
1283        queues_count = 0;
1284        spin_lock_init(&mq_lock);
1285
1286        return 0;
1287
1288out_filesystem:
1289        unregister_filesystem(&mqueue_fs_type);
1290out_sysctl:
1291        if (mq_sysctl_table)
1292                unregister_sysctl_table(mq_sysctl_table);
1293        kmem_cache_destroy(mqueue_inode_cachep);
1294        return error;
1295}
1296
1297__initcall(init_mqueue_fs);
1298