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#include <linux/ipc_namespace.h>
  35#include <linux/slab.h>
  36
  37#include <net/sock.h>
  38#include "util.h"
  39
  40#define MQUEUE_MAGIC    0x19800202
  41#define DIRENT_SIZE     20
  42#define FILENT_SIZE     80
  43
  44#define SEND            0
  45#define RECV            1
  46
  47#define STATE_NONE      0
  48#define STATE_PENDING   1
  49#define STATE_READY     2
  50
  51struct ext_wait_queue {         /* queue of sleeping tasks */
  52        struct task_struct *task;
  53        struct list_head list;
  54        struct msg_msg *msg;    /* ptr of loaded message */
  55        int state;              /* one of STATE_* values */
  56};
  57
  58struct mqueue_inode_info {
  59        spinlock_t lock;
  60        struct inode vfs_inode;
  61        wait_queue_head_t wait_q;
  62
  63        struct msg_msg **messages;
  64        struct mq_attr attr;
  65
  66        struct sigevent notify;
  67        struct pid* notify_owner;
  68        struct user_struct *user;       /* user who created, for accounting */
  69        struct sock *notify_sock;
  70        struct sk_buff *notify_cookie;
  71
  72        /* for tasks waiting for free space and messages, respectively */
  73        struct ext_wait_queue e_wait_q[2];
  74
  75        unsigned long qsize; /* size of queue in memory (sum of all msgs) */
  76};
  77
  78static const struct inode_operations mqueue_dir_inode_operations;
  79static const struct file_operations mqueue_file_operations;
  80static const struct super_operations mqueue_super_ops;
  81static void remove_notification(struct mqueue_inode_info *info);
  82
  83static struct kmem_cache *mqueue_inode_cachep;
  84
  85static struct ctl_table_header * mq_sysctl_table;
  86
  87static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
  88{
  89        return container_of(inode, struct mqueue_inode_info, vfs_inode);
  90}
  91
  92/*
  93 * This routine should be called with the mq_lock held.
  94 */
  95static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
  96{
  97        return get_ipc_ns(inode->i_sb->s_fs_info);
  98}
  99
 100static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
 101{
 102        struct ipc_namespace *ns;
 103
 104        spin_lock(&mq_lock);
 105        ns = __get_ns_from_inode(inode);
 106        spin_unlock(&mq_lock);
 107        return ns;
 108}
 109
 110static struct inode *mqueue_get_inode(struct super_block *sb,
 111                struct ipc_namespace *ipc_ns, int mode,
 112                struct mq_attr *attr)
 113{
 114        struct user_struct *u = current_user();
 115        struct inode *inode;
 116        int ret = -ENOMEM;
 117
 118        inode = new_inode(sb);
 119        if (!inode)
 120                goto err;
 121
 122        inode->i_ino = get_next_ino();
 123        inode->i_mode = mode;
 124        inode->i_uid = current_fsuid();
 125        inode->i_gid = current_fsgid();
 126        inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME;
 127
 128        if (S_ISREG(mode)) {
 129                struct mqueue_inode_info *info;
 130                struct task_struct *p = current;
 131                unsigned long mq_bytes, mq_msg_tblsz;
 132
 133                inode->i_fop = &mqueue_file_operations;
 134                inode->i_size = FILENT_SIZE;
 135                /* mqueue specific info */
 136                info = MQUEUE_I(inode);
 137                spin_lock_init(&info->lock);
 138                init_waitqueue_head(&info->wait_q);
 139                INIT_LIST_HEAD(&info->e_wait_q[0].list);
 140                INIT_LIST_HEAD(&info->e_wait_q[1].list);
 141                info->notify_owner = NULL;
 142                info->qsize = 0;
 143                info->user = NULL;      /* set when all is ok */
 144                memset(&info->attr, 0, sizeof(info->attr));
 145                info->attr.mq_maxmsg = ipc_ns->mq_msg_max;
 146                info->attr.mq_msgsize = ipc_ns->mq_msgsize_max;
 147                if (attr) {
 148                        info->attr.mq_maxmsg = attr->mq_maxmsg;
 149                        info->attr.mq_msgsize = attr->mq_msgsize;
 150                }
 151                mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
 152                info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
 153                if (!info->messages)
 154                        goto out_inode;
 155
 156                mq_bytes = (mq_msg_tblsz +
 157                        (info->attr.mq_maxmsg * info->attr.mq_msgsize));
 158
 159                spin_lock(&mq_lock);
 160                if (u->mq_bytes + mq_bytes < u->mq_bytes ||
 161                    u->mq_bytes + mq_bytes > task_rlimit(p, RLIMIT_MSGQUEUE)) {
 162                        spin_unlock(&mq_lock);
 163                        /* mqueue_evict_inode() releases info->messages */
 164                        ret = -EMFILE;
 165                        goto out_inode;
 166                }
 167                u->mq_bytes += mq_bytes;
 168                spin_unlock(&mq_lock);
 169
 170                /* all is ok */
 171                info->user = get_uid(u);
 172        } else if (S_ISDIR(mode)) {
 173                inc_nlink(inode);
 174                /* Some things misbehave if size == 0 on a directory */
 175                inode->i_size = 2 * DIRENT_SIZE;
 176                inode->i_op = &mqueue_dir_inode_operations;
 177                inode->i_fop = &simple_dir_operations;
 178        }
 179
 180        return inode;
 181out_inode:
 182        iput(inode);
 183err:
 184        return ERR_PTR(ret);
 185}
 186
 187static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
 188{
 189        struct inode *inode;
 190        struct ipc_namespace *ns = data;
 191        int error;
 192
 193        sb->s_blocksize = PAGE_CACHE_SIZE;
 194        sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 195        sb->s_magic = MQUEUE_MAGIC;
 196        sb->s_op = &mqueue_super_ops;
 197
 198        inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO,
 199                                NULL);
 200        if (IS_ERR(inode)) {
 201                error = PTR_ERR(inode);
 202                goto out;
 203        }
 204
 205        sb->s_root = d_alloc_root(inode);
 206        if (!sb->s_root) {
 207                iput(inode);
 208                error = -ENOMEM;
 209                goto out;
 210        }
 211        error = 0;
 212
 213out:
 214        return error;
 215}
 216
 217static struct dentry *mqueue_mount(struct file_system_type *fs_type,
 218                         int flags, const char *dev_name,
 219                         void *data)
 220{
 221        if (!(flags & MS_KERNMOUNT))
 222                data = current->nsproxy->ipc_ns;
 223        return mount_ns(fs_type, flags, data, mqueue_fill_super);
 224}
 225
 226static void init_once(void *foo)
 227{
 228        struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
 229
 230        inode_init_once(&p->vfs_inode);
 231}
 232
 233static struct inode *mqueue_alloc_inode(struct super_block *sb)
 234{
 235        struct mqueue_inode_info *ei;
 236
 237        ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
 238        if (!ei)
 239                return NULL;
 240        return &ei->vfs_inode;
 241}
 242
 243static void mqueue_i_callback(struct rcu_head *head)
 244{
 245        struct inode *inode = container_of(head, struct inode, i_rcu);
 246        INIT_LIST_HEAD(&inode->i_dentry);
 247        kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
 248}
 249
 250static void mqueue_destroy_inode(struct inode *inode)
 251{
 252        call_rcu(&inode->i_rcu, mqueue_i_callback);
 253}
 254
 255static void mqueue_evict_inode(struct inode *inode)
 256{
 257        struct mqueue_inode_info *info;
 258        struct user_struct *user;
 259        unsigned long mq_bytes;
 260        int i;
 261        struct ipc_namespace *ipc_ns;
 262
 263        end_writeback(inode);
 264
 265        if (S_ISDIR(inode->i_mode))
 266                return;
 267
 268        ipc_ns = get_ns_from_inode(inode);
 269        info = MQUEUE_I(inode);
 270        spin_lock(&info->lock);
 271        for (i = 0; i < info->attr.mq_curmsgs; i++)
 272                free_msg(info->messages[i]);
 273        kfree(info->messages);
 274        spin_unlock(&info->lock);
 275
 276        /* Total amount of bytes accounted for the mqueue */
 277        mq_bytes = info->attr.mq_maxmsg * (sizeof(struct msg_msg *)
 278            + info->attr.mq_msgsize);
 279        user = info->user;
 280        if (user) {
 281                spin_lock(&mq_lock);
 282                user->mq_bytes -= mq_bytes;
 283                /*
 284                 * get_ns_from_inode() ensures that the
 285                 * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
 286                 * to which we now hold a reference, or it is NULL.
 287                 * We can't put it here under mq_lock, though.
 288                 */
 289                if (ipc_ns)
 290                        ipc_ns->mq_queues_count--;
 291                spin_unlock(&mq_lock);
 292                free_uid(user);
 293        }
 294        if (ipc_ns)
 295                put_ipc_ns(ipc_ns);
 296}
 297
 298static int mqueue_create(struct inode *dir, struct dentry *dentry,
 299                                int mode, struct nameidata *nd)
 300{
 301        struct inode *inode;
 302        struct mq_attr *attr = dentry->d_fsdata;
 303        int error;
 304        struct ipc_namespace *ipc_ns;
 305
 306        spin_lock(&mq_lock);
 307        ipc_ns = __get_ns_from_inode(dir);
 308        if (!ipc_ns) {
 309                error = -EACCES;
 310                goto out_unlock;
 311        }
 312        if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
 313                        !capable(CAP_SYS_RESOURCE)) {
 314                error = -ENOSPC;
 315                goto out_unlock;
 316        }
 317        ipc_ns->mq_queues_count++;
 318        spin_unlock(&mq_lock);
 319
 320        inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
 321        if (IS_ERR(inode)) {
 322                error = PTR_ERR(inode);
 323                spin_lock(&mq_lock);
 324                ipc_ns->mq_queues_count--;
 325                goto out_unlock;
 326        }
 327
 328        put_ipc_ns(ipc_ns);
 329        dir->i_size += DIRENT_SIZE;
 330        dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 331
 332        d_instantiate(dentry, inode);
 333        dget(dentry);
 334        return 0;
 335out_unlock:
 336        spin_unlock(&mq_lock);
 337        if (ipc_ns)
 338                put_ipc_ns(ipc_ns);
 339        return error;
 340}
 341
 342static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
 343{
 344        struct inode *inode = dentry->d_inode;
 345
 346        dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 347        dir->i_size -= DIRENT_SIZE;
 348        drop_nlink(inode);
 349        dput(dentry);
 350        return 0;
 351}
 352
 353/*
 354*       This is routine for system read from queue file.
 355*       To avoid mess with doing here some sort of mq_receive we allow
 356*       to read only queue size & notification info (the only values
 357*       that are interesting from user point of view and aren't accessible
 358*       through std routines)
 359*/
 360static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
 361                                size_t count, loff_t *off)
 362{
 363        struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 364        char buffer[FILENT_SIZE];
 365        ssize_t ret;
 366
 367        spin_lock(&info->lock);
 368        snprintf(buffer, sizeof(buffer),
 369                        "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
 370                        info->qsize,
 371                        info->notify_owner ? info->notify.sigev_notify : 0,
 372                        (info->notify_owner &&
 373                         info->notify.sigev_notify == SIGEV_SIGNAL) ?
 374                                info->notify.sigev_signo : 0,
 375                        pid_vnr(info->notify_owner));
 376        spin_unlock(&info->lock);
 377        buffer[sizeof(buffer)-1] = '\0';
 378
 379        ret = simple_read_from_buffer(u_data, count, off, buffer,
 380                                strlen(buffer));
 381        if (ret <= 0)
 382                return ret;
 383
 384        filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
 385        return ret;
 386}
 387
 388static int mqueue_flush_file(struct file *filp, fl_owner_t id)
 389{
 390        struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 391
 392        spin_lock(&info->lock);
 393        if (task_tgid(current) == info->notify_owner)
 394                remove_notification(info);
 395
 396        spin_unlock(&info->lock);
 397        return 0;
 398}
 399
 400static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
 401{
 402        struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 403        int retval = 0;
 404
 405        poll_wait(filp, &info->wait_q, poll_tab);
 406
 407        spin_lock(&info->lock);
 408        if (info->attr.mq_curmsgs)
 409                retval = POLLIN | POLLRDNORM;
 410
 411        if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
 412                retval |= POLLOUT | POLLWRNORM;
 413        spin_unlock(&info->lock);
 414
 415        return retval;
 416}
 417
 418/* Adds current to info->e_wait_q[sr] before element with smaller prio */
 419static void wq_add(struct mqueue_inode_info *info, int sr,
 420                        struct ext_wait_queue *ewp)
 421{
 422        struct ext_wait_queue *walk;
 423
 424        ewp->task = current;
 425
 426        list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
 427                if (walk->task->static_prio <= current->static_prio) {
 428                        list_add_tail(&ewp->list, &walk->list);
 429                        return;
 430                }
 431        }
 432        list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
 433}
 434
 435/*
 436 * Puts current task to sleep. Caller must hold queue lock. After return
 437 * lock isn't held.
 438 * sr: SEND or RECV
 439 */
 440static int wq_sleep(struct mqueue_inode_info *info, int sr,
 441                    ktime_t *timeout, struct ext_wait_queue *ewp)
 442{
 443        int retval;
 444        signed long time;
 445
 446        wq_add(info, sr, ewp);
 447
 448        for (;;) {
 449                set_current_state(TASK_INTERRUPTIBLE);
 450
 451                spin_unlock(&info->lock);
 452                time = schedule_hrtimeout_range_clock(timeout,
 453                    HRTIMER_MODE_ABS, 0, CLOCK_REALTIME);
 454
 455                while (ewp->state == STATE_PENDING)
 456                        cpu_relax();
 457
 458                if (ewp->state == STATE_READY) {
 459                        retval = 0;
 460                        goto out;
 461                }
 462                spin_lock(&info->lock);
 463                if (ewp->state == STATE_READY) {
 464                        retval = 0;
 465                        goto out_unlock;
 466                }
 467                if (signal_pending(current)) {
 468                        retval = -ERESTARTSYS;
 469                        break;
 470                }
 471                if (time == 0) {
 472                        retval = -ETIMEDOUT;
 473                        break;
 474                }
 475        }
 476        list_del(&ewp->list);
 477out_unlock:
 478        spin_unlock(&info->lock);
 479out:
 480        return retval;
 481}
 482
 483/*
 484 * Returns waiting task that should be serviced first or NULL if none exists
 485 */
 486static struct ext_wait_queue *wq_get_first_waiter(
 487                struct mqueue_inode_info *info, int sr)
 488{
 489        struct list_head *ptr;
 490
 491        ptr = info->e_wait_q[sr].list.prev;
 492        if (ptr == &info->e_wait_q[sr].list)
 493                return NULL;
 494        return list_entry(ptr, struct ext_wait_queue, list);
 495}
 496
 497/* Auxiliary functions to manipulate messages' list */
 498static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
 499{
 500        int k;
 501
 502        k = info->attr.mq_curmsgs - 1;
 503        while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
 504                info->messages[k + 1] = info->messages[k];
 505                k--;
 506        }
 507        info->attr.mq_curmsgs++;
 508        info->qsize += ptr->m_ts;
 509        info->messages[k + 1] = ptr;
 510}
 511
 512static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
 513{
 514        info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
 515        return info->messages[info->attr.mq_curmsgs];
 516}
 517
 518static inline void set_cookie(struct sk_buff *skb, char code)
 519{
 520        ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
 521}
 522
 523/*
 524 * The next function is only to split too long sys_mq_timedsend
 525 */
 526static void __do_notify(struct mqueue_inode_info *info)
 527{
 528        /* notification
 529         * invoked when there is registered process and there isn't process
 530         * waiting synchronously for message AND state of queue changed from
 531         * empty to not empty. Here we are sure that no one is waiting
 532         * synchronously. */
 533        if (info->notify_owner &&
 534            info->attr.mq_curmsgs == 1) {
 535                struct siginfo sig_i;
 536                switch (info->notify.sigev_notify) {
 537                case SIGEV_NONE:
 538                        break;
 539                case SIGEV_SIGNAL:
 540                        /* sends signal */
 541
 542                        sig_i.si_signo = info->notify.sigev_signo;
 543                        sig_i.si_errno = 0;
 544                        sig_i.si_code = SI_MESGQ;
 545                        sig_i.si_value = info->notify.sigev_value;
 546                        sig_i.si_pid = task_tgid_nr_ns(current,
 547                                                ns_of_pid(info->notify_owner));
 548                        sig_i.si_uid = current_uid();
 549
 550                        kill_pid_info(info->notify.sigev_signo,
 551                                      &sig_i, info->notify_owner);
 552                        break;
 553                case SIGEV_THREAD:
 554                        set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
 555                        netlink_sendskb(info->notify_sock, info->notify_cookie);
 556                        break;
 557                }
 558                /* after notification unregisters process */
 559                put_pid(info->notify_owner);
 560                info->notify_owner = NULL;
 561        }
 562        wake_up(&info->wait_q);
 563}
 564
 565static int prepare_timeout(const struct timespec __user *u_abs_timeout,
 566                           ktime_t *expires, struct timespec *ts)
 567{
 568        if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec)))
 569                return -EFAULT;
 570        if (!timespec_valid(ts))
 571                return -EINVAL;
 572
 573        *expires = timespec_to_ktime(*ts);
 574        return 0;
 575}
 576
 577static void remove_notification(struct mqueue_inode_info *info)
 578{
 579        if (info->notify_owner != NULL &&
 580            info->notify.sigev_notify == SIGEV_THREAD) {
 581                set_cookie(info->notify_cookie, NOTIFY_REMOVED);
 582                netlink_sendskb(info->notify_sock, info->notify_cookie);
 583        }
 584        put_pid(info->notify_owner);
 585        info->notify_owner = NULL;
 586}
 587
 588static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
 589{
 590        if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
 591                return 0;
 592        if (capable(CAP_SYS_RESOURCE)) {
 593                if (attr->mq_maxmsg > HARD_MSGMAX)
 594                        return 0;
 595        } else {
 596                if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
 597                                attr->mq_msgsize > ipc_ns->mq_msgsize_max)
 598                        return 0;
 599        }
 600        /* check for overflow */
 601        if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
 602                return 0;
 603        if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize
 604            + sizeof (struct msg_msg *))) <
 605            (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
 606                return 0;
 607        return 1;
 608}
 609
 610/*
 611 * Invoked when creating a new queue via sys_mq_open
 612 */
 613static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir,
 614                        struct dentry *dentry, int oflag, mode_t mode,
 615                        struct mq_attr *attr)
 616{
 617        const struct cred *cred = current_cred();
 618        struct file *result;
 619        int ret;
 620
 621        if (attr) {
 622                if (!mq_attr_ok(ipc_ns, attr)) {
 623                        ret = -EINVAL;
 624                        goto out;
 625                }
 626                /* store for use during create */
 627                dentry->d_fsdata = attr;
 628        }
 629
 630        mode &= ~current_umask();
 631        ret = mnt_want_write(ipc_ns->mq_mnt);
 632        if (ret)
 633                goto out;
 634        ret = vfs_create(dir->d_inode, dentry, mode, NULL);
 635        dentry->d_fsdata = NULL;
 636        if (ret)
 637                goto out_drop_write;
 638
 639        result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
 640        /*
 641         * dentry_open() took a persistent mnt_want_write(),
 642         * so we can now drop this one.
 643         */
 644        mnt_drop_write(ipc_ns->mq_mnt);
 645        return result;
 646
 647out_drop_write:
 648        mnt_drop_write(ipc_ns->mq_mnt);
 649out:
 650        dput(dentry);
 651        mntput(ipc_ns->mq_mnt);
 652        return ERR_PTR(ret);
 653}
 654
 655/* Opens existing queue */
 656static struct file *do_open(struct ipc_namespace *ipc_ns,
 657                                struct dentry *dentry, int oflag)
 658{
 659        int ret;
 660        const struct cred *cred = current_cred();
 661
 662        static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
 663                                                  MAY_READ | MAY_WRITE };
 664
 665        if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
 666                ret = -EINVAL;
 667                goto err;
 668        }
 669
 670        if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
 671                ret = -EACCES;
 672                goto err;
 673        }
 674
 675        return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
 676
 677err:
 678        dput(dentry);
 679        mntput(ipc_ns->mq_mnt);
 680        return ERR_PTR(ret);
 681}
 682
 683SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, mode_t, mode,
 684                struct mq_attr __user *, u_attr)
 685{
 686        struct dentry *dentry;
 687        struct file *filp;
 688        char *name;
 689        struct mq_attr attr;
 690        int fd, error;
 691        struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
 692
 693        if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
 694                return -EFAULT;
 695
 696        audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
 697
 698        if (IS_ERR(name = getname(u_name)))
 699                return PTR_ERR(name);
 700
 701        fd = get_unused_fd_flags(O_CLOEXEC);
 702        if (fd < 0)
 703                goto out_putname;
 704
 705        mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 706        dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
 707        if (IS_ERR(dentry)) {
 708                error = PTR_ERR(dentry);
 709                goto out_putfd;
 710        }
 711        mntget(ipc_ns->mq_mnt);
 712
 713        if (oflag & O_CREAT) {
 714                if (dentry->d_inode) {  /* entry already exists */
 715                        audit_inode(name, dentry);
 716                        if (oflag & O_EXCL) {
 717                                error = -EEXIST;
 718                                goto out;
 719                        }
 720                        filp = do_open(ipc_ns, dentry, oflag);
 721                } else {
 722                        filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root,
 723                                                dentry, oflag, mode,
 724                                                u_attr ? &attr : NULL);
 725                }
 726        } else {
 727                if (!dentry->d_inode) {
 728                        error = -ENOENT;
 729                        goto out;
 730                }
 731                audit_inode(name, dentry);
 732                filp = do_open(ipc_ns, dentry, oflag);
 733        }
 734
 735        if (IS_ERR(filp)) {
 736                error = PTR_ERR(filp);
 737                goto out_putfd;
 738        }
 739
 740        fd_install(fd, filp);
 741        goto out_upsem;
 742
 743out:
 744        dput(dentry);
 745        mntput(ipc_ns->mq_mnt);
 746out_putfd:
 747        put_unused_fd(fd);
 748        fd = error;
 749out_upsem:
 750        mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 751out_putname:
 752        putname(name);
 753        return fd;
 754}
 755
 756SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
 757{
 758        int err;
 759        char *name;
 760        struct dentry *dentry;
 761        struct inode *inode = NULL;
 762        struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
 763
 764        name = getname(u_name);
 765        if (IS_ERR(name))
 766                return PTR_ERR(name);
 767
 768        mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
 769                        I_MUTEX_PARENT);
 770        dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
 771        if (IS_ERR(dentry)) {
 772                err = PTR_ERR(dentry);
 773                goto out_unlock;
 774        }
 775
 776        if (!dentry->d_inode) {
 777                err = -ENOENT;
 778                goto out_err;
 779        }
 780
 781        inode = dentry->d_inode;
 782        if (inode)
 783                ihold(inode);
 784        err = mnt_want_write(ipc_ns->mq_mnt);
 785        if (err)
 786                goto out_err;
 787        err = vfs_unlink(dentry->d_parent->d_inode, dentry);
 788        mnt_drop_write(ipc_ns->mq_mnt);
 789out_err:
 790        dput(dentry);
 791
 792out_unlock:
 793        mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 794        putname(name);
 795        if (inode)
 796                iput(inode);
 797
 798        return err;
 799}
 800
 801/* Pipelined send and receive functions.
 802 *
 803 * If a receiver finds no waiting message, then it registers itself in the
 804 * list of waiting receivers. A sender checks that list before adding the new
 805 * message into the message array. If there is a waiting receiver, then it
 806 * bypasses the message array and directly hands the message over to the
 807 * receiver.
 808 * The receiver accepts the message and returns without grabbing the queue
 809 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
 810 * are necessary. The same algorithm is used for sysv semaphores, see
 811 * ipc/sem.c for more details.
 812 *
 813 * The same algorithm is used for senders.
 814 */
 815
 816/* pipelined_send() - send a message directly to the task waiting in
 817 * sys_mq_timedreceive() (without inserting message into a queue).
 818 */
 819static inline void pipelined_send(struct mqueue_inode_info *info,
 820                                  struct msg_msg *message,
 821                                  struct ext_wait_queue *receiver)
 822{
 823        receiver->msg = message;
 824        list_del(&receiver->list);
 825        receiver->state = STATE_PENDING;
 826        wake_up_process(receiver->task);
 827        smp_wmb();
 828        receiver->state = STATE_READY;
 829}
 830
 831/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
 832 * gets its message and put to the queue (we have one free place for sure). */
 833static inline void pipelined_receive(struct mqueue_inode_info *info)
 834{
 835        struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
 836
 837        if (!sender) {
 838                /* for poll */
 839                wake_up_interruptible(&info->wait_q);
 840                return;
 841        }
 842        msg_insert(sender->msg, info);
 843        list_del(&sender->list);
 844        sender->state = STATE_PENDING;
 845        wake_up_process(sender->task);
 846        smp_wmb();
 847        sender->state = STATE_READY;
 848}
 849
 850SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
 851                size_t, msg_len, unsigned int, msg_prio,
 852                const struct timespec __user *, u_abs_timeout)
 853{
 854        struct file *filp;
 855        struct inode *inode;
 856        struct ext_wait_queue wait;
 857        struct ext_wait_queue *receiver;
 858        struct msg_msg *msg_ptr;
 859        struct mqueue_inode_info *info;
 860        ktime_t expires, *timeout = NULL;
 861        struct timespec ts;
 862        int ret;
 863
 864        if (u_abs_timeout) {
 865                int res = prepare_timeout(u_abs_timeout, &expires, &ts);
 866                if (res)
 867                        return res;
 868                timeout = &expires;
 869        }
 870
 871        if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
 872                return -EINVAL;
 873
 874        audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL);
 875
 876        filp = fget(mqdes);
 877        if (unlikely(!filp)) {
 878                ret = -EBADF;
 879                goto out;
 880        }
 881
 882        inode = filp->f_path.dentry->d_inode;
 883        if (unlikely(filp->f_op != &mqueue_file_operations)) {
 884                ret = -EBADF;
 885                goto out_fput;
 886        }
 887        info = MQUEUE_I(inode);
 888        audit_inode(NULL, filp->f_path.dentry);
 889
 890        if (unlikely(!(filp->f_mode & FMODE_WRITE))) {
 891                ret = -EBADF;
 892                goto out_fput;
 893        }
 894
 895        if (unlikely(msg_len > info->attr.mq_msgsize)) {
 896                ret = -EMSGSIZE;
 897                goto out_fput;
 898        }
 899
 900        /* First try to allocate memory, before doing anything with
 901         * existing queues. */
 902        msg_ptr = load_msg(u_msg_ptr, msg_len);
 903        if (IS_ERR(msg_ptr)) {
 904                ret = PTR_ERR(msg_ptr);
 905                goto out_fput;
 906        }
 907        msg_ptr->m_ts = msg_len;
 908        msg_ptr->m_type = msg_prio;
 909
 910        spin_lock(&info->lock);
 911
 912        if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
 913                if (filp->f_flags & O_NONBLOCK) {
 914                        spin_unlock(&info->lock);
 915                        ret = -EAGAIN;
 916                } else {
 917                        wait.task = current;
 918                        wait.msg = (void *) msg_ptr;
 919                        wait.state = STATE_NONE;
 920                        ret = wq_sleep(info, SEND, timeout, &wait);
 921                }
 922                if (ret < 0)
 923                        free_msg(msg_ptr);
 924        } else {
 925                receiver = wq_get_first_waiter(info, RECV);
 926                if (receiver) {
 927                        pipelined_send(info, msg_ptr, receiver);
 928                } else {
 929                        /* adds message to the queue */
 930                        msg_insert(msg_ptr, info);
 931                        __do_notify(info);
 932                }
 933                inode->i_atime = inode->i_mtime = inode->i_ctime =
 934                                CURRENT_TIME;
 935                spin_unlock(&info->lock);
 936                ret = 0;
 937        }
 938out_fput:
 939        fput(filp);
 940out:
 941        return ret;
 942}
 943
 944SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
 945                size_t, msg_len, unsigned int __user *, u_msg_prio,
 946                const struct timespec __user *, u_abs_timeout)
 947{
 948        ssize_t ret;
 949        struct msg_msg *msg_ptr;
 950        struct file *filp;
 951        struct inode *inode;
 952        struct mqueue_inode_info *info;
 953        struct ext_wait_queue wait;
 954        ktime_t expires, *timeout = NULL;
 955        struct timespec ts;
 956
 957        if (u_abs_timeout) {
 958                int res = prepare_timeout(u_abs_timeout, &expires, &ts);
 959                if (res)
 960                        return res;
 961                timeout = &expires;
 962        }
 963
 964        audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
 965
 966        filp = fget(mqdes);
 967        if (unlikely(!filp)) {
 968                ret = -EBADF;
 969                goto out;
 970        }
 971
 972        inode = filp->f_path.dentry->d_inode;
 973        if (unlikely(filp->f_op != &mqueue_file_operations)) {
 974                ret = -EBADF;
 975                goto out_fput;
 976        }
 977        info = MQUEUE_I(inode);
 978        audit_inode(NULL, filp->f_path.dentry);
 979
 980        if (unlikely(!(filp->f_mode & FMODE_READ))) {
 981                ret = -EBADF;
 982                goto out_fput;
 983        }
 984
 985        /* checks if buffer is big enough */
 986        if (unlikely(msg_len < info->attr.mq_msgsize)) {
 987                ret = -EMSGSIZE;
 988                goto out_fput;
 989        }
 990
 991        spin_lock(&info->lock);
 992        if (info->attr.mq_curmsgs == 0) {
 993                if (filp->f_flags & O_NONBLOCK) {
 994                        spin_unlock(&info->lock);
 995                        ret = -EAGAIN;
 996                } else {
 997                        wait.task = current;
 998                        wait.state = STATE_NONE;
 999                        ret = wq_sleep(info, RECV, timeout, &wait);
1000                        msg_ptr = wait.msg;
1001                }
1002        } else {
1003                msg_ptr = msg_get(info);
1004
1005                inode->i_atime = inode->i_mtime = inode->i_ctime =
1006                                CURRENT_TIME;
1007
1008                /* There is now free space in queue. */
1009                pipelined_receive(info);
1010                spin_unlock(&info->lock);
1011                ret = 0;
1012        }
1013        if (ret == 0) {
1014                ret = msg_ptr->m_ts;
1015
1016                if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1017                        store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1018                        ret = -EFAULT;
1019                }
1020                free_msg(msg_ptr);
1021        }
1022out_fput:
1023        fput(filp);
1024out:
1025        return ret;
1026}
1027
1028/*
1029 * Notes: the case when user wants us to deregister (with NULL as pointer)
1030 * and he isn't currently owner of notification, will be silently discarded.
1031 * It isn't explicitly defined in the POSIX.
1032 */
1033SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1034                const struct sigevent __user *, u_notification)
1035{
1036        int ret;
1037        struct file *filp;
1038        struct sock *sock;
1039        struct inode *inode;
1040        struct sigevent notification;
1041        struct mqueue_inode_info *info;
1042        struct sk_buff *nc;
1043
1044        if (u_notification) {
1045                if (copy_from_user(&notification, u_notification,
1046                                        sizeof(struct sigevent)))
1047                        return -EFAULT;
1048        }
1049
1050        audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1051
1052        nc = NULL;
1053        sock = NULL;
1054        if (u_notification != NULL) {
1055                if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1056                             notification.sigev_notify != SIGEV_SIGNAL &&
1057                             notification.sigev_notify != SIGEV_THREAD))
1058                        return -EINVAL;
1059                if (notification.sigev_notify == SIGEV_SIGNAL &&
1060                        !valid_signal(notification.sigev_signo)) {
1061                        return -EINVAL;
1062                }
1063                if (notification.sigev_notify == SIGEV_THREAD) {
1064                        long timeo;
1065
1066                        /* create the notify skb */
1067                        nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1068                        if (!nc) {
1069                                ret = -ENOMEM;
1070                                goto out;
1071                        }
1072                        if (copy_from_user(nc->data,
1073                                        notification.sigev_value.sival_ptr,
1074                                        NOTIFY_COOKIE_LEN)) {
1075                                ret = -EFAULT;
1076                                goto out;
1077                        }
1078
1079                        /* TODO: add a header? */
1080                        skb_put(nc, NOTIFY_COOKIE_LEN);
1081                        /* and attach it to the socket */
1082retry:
1083                        filp = fget(notification.sigev_signo);
1084                        if (!filp) {
1085                                ret = -EBADF;
1086                                goto out;
1087                        }
1088                        sock = netlink_getsockbyfilp(filp);
1089                        fput(filp);
1090                        if (IS_ERR(sock)) {
1091                                ret = PTR_ERR(sock);
1092                                sock = NULL;
1093                                goto out;
1094                        }
1095
1096                        timeo = MAX_SCHEDULE_TIMEOUT;
1097                        ret = netlink_attachskb(sock, nc, &timeo, NULL);
1098                        if (ret == 1)
1099                                goto retry;
1100                        if (ret) {
1101                                sock = NULL;
1102                                nc = NULL;
1103                                goto out;
1104                        }
1105                }
1106        }
1107
1108        filp = fget(mqdes);
1109        if (!filp) {
1110                ret = -EBADF;
1111                goto out;
1112        }
1113
1114        inode = filp->f_path.dentry->d_inode;
1115        if (unlikely(filp->f_op != &mqueue_file_operations)) {
1116                ret = -EBADF;
1117                goto out_fput;
1118        }
1119        info = MQUEUE_I(inode);
1120
1121        ret = 0;
1122        spin_lock(&info->lock);
1123        if (u_notification == NULL) {
1124                if (info->notify_owner == task_tgid(current)) {
1125                        remove_notification(info);
1126                        inode->i_atime = inode->i_ctime = CURRENT_TIME;
1127                }
1128        } else if (info->notify_owner != NULL) {
1129                ret = -EBUSY;
1130        } else {
1131                switch (notification.sigev_notify) {
1132                case SIGEV_NONE:
1133                        info->notify.sigev_notify = SIGEV_NONE;
1134                        break;
1135                case SIGEV_THREAD:
1136                        info->notify_sock = sock;
1137                        info->notify_cookie = nc;
1138                        sock = NULL;
1139                        nc = NULL;
1140                        info->notify.sigev_notify = SIGEV_THREAD;
1141                        break;
1142                case SIGEV_SIGNAL:
1143                        info->notify.sigev_signo = notification.sigev_signo;
1144                        info->notify.sigev_value = notification.sigev_value;
1145                        info->notify.sigev_notify = SIGEV_SIGNAL;
1146                        break;
1147                }
1148
1149                info->notify_owner = get_pid(task_tgid(current));
1150                inode->i_atime = inode->i_ctime = CURRENT_TIME;
1151        }
1152        spin_unlock(&info->lock);
1153out_fput:
1154        fput(filp);
1155out:
1156        if (sock) {
1157                netlink_detachskb(sock, nc);
1158        } else if (nc) {
1159                dev_kfree_skb(nc);
1160        }
1161        return ret;
1162}
1163
1164SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1165                const struct mq_attr __user *, u_mqstat,
1166                struct mq_attr __user *, u_omqstat)
1167{
1168        int ret;
1169        struct mq_attr mqstat, omqstat;
1170        struct file *filp;
1171        struct inode *inode;
1172        struct mqueue_inode_info *info;
1173
1174        if (u_mqstat != NULL) {
1175                if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1176                        return -EFAULT;
1177                if (mqstat.mq_flags & (~O_NONBLOCK))
1178                        return -EINVAL;
1179        }
1180
1181        filp = fget(mqdes);
1182        if (!filp) {
1183                ret = -EBADF;
1184                goto out;
1185        }
1186
1187        inode = filp->f_path.dentry->d_inode;
1188        if (unlikely(filp->f_op != &mqueue_file_operations)) {
1189                ret = -EBADF;
1190                goto out_fput;
1191        }
1192        info = MQUEUE_I(inode);
1193
1194        spin_lock(&info->lock);
1195
1196        omqstat = info->attr;
1197        omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1198        if (u_mqstat) {
1199                audit_mq_getsetattr(mqdes, &mqstat);
1200                spin_lock(&filp->f_lock);
1201                if (mqstat.mq_flags & O_NONBLOCK)
1202                        filp->f_flags |= O_NONBLOCK;
1203                else
1204                        filp->f_flags &= ~O_NONBLOCK;
1205                spin_unlock(&filp->f_lock);
1206
1207                inode->i_atime = inode->i_ctime = CURRENT_TIME;
1208        }
1209
1210        spin_unlock(&info->lock);
1211
1212        ret = 0;
1213        if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1214                                                sizeof(struct mq_attr)))
1215                ret = -EFAULT;
1216
1217out_fput:
1218        fput(filp);
1219out:
1220        return ret;
1221}
1222
1223static const struct inode_operations mqueue_dir_inode_operations = {
1224        .lookup = simple_lookup,
1225        .create = mqueue_create,
1226        .unlink = mqueue_unlink,
1227};
1228
1229static const struct file_operations mqueue_file_operations = {
1230        .flush = mqueue_flush_file,
1231        .poll = mqueue_poll_file,
1232        .read = mqueue_read_file,
1233        .llseek = default_llseek,
1234};
1235
1236static const struct super_operations mqueue_super_ops = {
1237        .alloc_inode = mqueue_alloc_inode,
1238        .destroy_inode = mqueue_destroy_inode,
1239        .evict_inode = mqueue_evict_inode,
1240        .statfs = simple_statfs,
1241};
1242
1243static struct file_system_type mqueue_fs_type = {
1244        .name = "mqueue",
1245        .mount = mqueue_mount,
1246        .kill_sb = kill_litter_super,
1247};
1248
1249int mq_init_ns(struct ipc_namespace *ns)
1250{
1251        ns->mq_queues_count  = 0;
1252        ns->mq_queues_max    = DFLT_QUEUESMAX;
1253        ns->mq_msg_max       = DFLT_MSGMAX;
1254        ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1255
1256        ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1257        if (IS_ERR(ns->mq_mnt)) {
1258                int err = PTR_ERR(ns->mq_mnt);
1259                ns->mq_mnt = NULL;
1260                return err;
1261        }
1262        return 0;
1263}
1264
1265void mq_clear_sbinfo(struct ipc_namespace *ns)
1266{
1267        ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1268}
1269
1270void mq_put_mnt(struct ipc_namespace *ns)
1271{
1272        mntput(ns->mq_mnt);
1273}
1274
1275static int __init init_mqueue_fs(void)
1276{
1277        int error;
1278
1279        mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1280                                sizeof(struct mqueue_inode_info), 0,
1281                                SLAB_HWCACHE_ALIGN, init_once);
1282        if (mqueue_inode_cachep == NULL)
1283                return -ENOMEM;
1284
1285        /* ignore failures - they are not fatal */
1286        mq_sysctl_table = mq_register_sysctl_table();
1287
1288        error = register_filesystem(&mqueue_fs_type);
1289        if (error)
1290                goto out_sysctl;
1291
1292        spin_lock_init(&mq_lock);
1293
1294        init_ipc_ns.mq_mnt = kern_mount_data(&mqueue_fs_type, &init_ipc_ns);
1295        if (IS_ERR(init_ipc_ns.mq_mnt)) {
1296                error = PTR_ERR(init_ipc_ns.mq_mnt);
1297                goto out_filesystem;
1298        }
1299
1300        return 0;
1301
1302out_filesystem:
1303        unregister_filesystem(&mqueue_fs_type);
1304out_sysctl:
1305        if (mq_sysctl_table)
1306                unregister_sysctl_table(mq_sysctl_table);
1307        kmem_cache_destroy(mqueue_inode_cachep);
1308        return error;
1309}
1310
1311__initcall(init_mqueue_fs);
1312
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