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