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/user_namespace.h>
  36#include <linux/slab.h>
  37
  38#include <net/sock.h>
  39#include "util.h"
  40
  41#define MQUEUE_MAGIC    0x19800202
  42#define DIRENT_SIZE     20
  43#define FILENT_SIZE     80
  44
  45#define SEND            0
  46#define RECV            1
  47
  48#define STATE_NONE      0
  49#define STATE_PENDING   1
  50#define STATE_READY     2
  51
  52struct ext_wait_queue {         /* queue of sleeping tasks */
  53        struct task_struct *task;
  54        struct list_head list;
  55        struct msg_msg *msg;    /* ptr of loaded message */
  56        int state;              /* one of STATE_* values */
  57};
  58
  59struct mqueue_inode_info {
  60        spinlock_t lock;
  61        struct inode vfs_inode;
  62        wait_queue_head_t wait_q;
  63
  64        struct msg_msg **messages;
  65        struct mq_attr attr;
  66
  67        struct sigevent notify;
  68        struct pid* notify_owner;
  69        struct user_struct *user;       /* user who created, for accounting */
  70        struct sock *notify_sock;
  71        struct sk_buff *notify_cookie;
  72
  73        /* for tasks waiting for free space and messages, respectively */
  74        struct ext_wait_queue e_wait_q[2];
  75
  76        unsigned long qsize; /* size of queue in memory (sum of all msgs) */
  77};
  78
  79static const struct inode_operations mqueue_dir_inode_operations;
  80static const struct file_operations mqueue_file_operations;
  81static const struct super_operations mqueue_super_ops;
  82static void remove_notification(struct mqueue_inode_info *info);
  83
  84static struct kmem_cache *mqueue_inode_cachep;
  85
  86static struct ctl_table_header * mq_sysctl_table;
  87
  88static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
  89{
  90        return container_of(inode, struct mqueue_inode_info, vfs_inode);
  91}
  92
  93/*
  94 * This routine should be called with the mq_lock held.
  95 */
  96static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
  97{
  98        return get_ipc_ns(inode->i_sb->s_fs_info);
  99}
 100
 101static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
 102{
 103        struct ipc_namespace *ns;
 104
 105        spin_lock(&mq_lock);
 106        ns = __get_ns_from_inode(inode);
 107        spin_unlock(&mq_lock);
 108        return ns;
 109}
 110
 111static struct inode *mqueue_get_inode(struct super_block *sb,
 112                struct ipc_namespace *ipc_ns, umode_t mode,
 113                struct mq_attr *attr)
 114{
 115        struct user_struct *u = current_user();
 116        struct inode *inode;
 117        int ret = -ENOMEM;
 118
 119        inode = new_inode(sb);
 120        if (!inode)
 121                goto err;
 122
 123        inode->i_ino = get_next_ino();
 124        inode->i_mode = mode;
 125        inode->i_uid = current_fsuid();
 126        inode->i_gid = current_fsgid();
 127        inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME;
 128
 129        if (S_ISREG(mode)) {
 130                struct mqueue_inode_info *info;
 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 > rlimit(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        kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
 247}
 248
 249static void mqueue_destroy_inode(struct inode *inode)
 250{
 251        call_rcu(&inode->i_rcu, mqueue_i_callback);
 252}
 253
 254static void mqueue_evict_inode(struct inode *inode)
 255{
 256        struct mqueue_inode_info *info;
 257        struct user_struct *user;
 258        unsigned long mq_bytes;
 259        int i;
 260        struct ipc_namespace *ipc_ns;
 261
 262        end_writeback(inode);
 263
 264        if (S_ISDIR(inode->i_mode))
 265                return;
 266
 267        ipc_ns = get_ns_from_inode(inode);
 268        info = MQUEUE_I(inode);
 269        spin_lock(&info->lock);
 270        for (i = 0; i < info->attr.mq_curmsgs; i++)
 271                free_msg(info->messages[i]);
 272        kfree(info->messages);
 273        spin_unlock(&info->lock);
 274
 275        /* Total amount of bytes accounted for the mqueue */
 276        mq_bytes = info->attr.mq_maxmsg * (sizeof(struct msg_msg *)
 277            + info->attr.mq_msgsize);
 278        user = info->user;
 279        if (user) {
 280                spin_lock(&mq_lock);
 281                user->mq_bytes -= mq_bytes;
 282                /*
 283                 * get_ns_from_inode() ensures that the
 284                 * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
 285                 * to which we now hold a reference, or it is NULL.
 286                 * We can't put it here under mq_lock, though.
 287                 */
 288                if (ipc_ns)
 289                        ipc_ns->mq_queues_count--;
 290                spin_unlock(&mq_lock);
 291                free_uid(user);
 292        }
 293        if (ipc_ns)
 294                put_ipc_ns(ipc_ns);
 295}
 296
 297static int mqueue_create(struct inode *dir, struct dentry *dentry,
 298                                umode_t mode, struct nameidata *nd)
 299{
 300        struct inode *inode;
 301        struct mq_attr *attr = dentry->d_fsdata;
 302        int error;
 303        struct ipc_namespace *ipc_ns;
 304
 305        spin_lock(&mq_lock);
 306        ipc_ns = __get_ns_from_inode(dir);
 307        if (!ipc_ns) {
 308                error = -EACCES;
 309                goto out_unlock;
 310        }
 311        if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
 312                        !capable(CAP_SYS_RESOURCE)) {
 313                error = -ENOSPC;
 314                goto out_unlock;
 315        }
 316        ipc_ns->mq_queues_count++;
 317        spin_unlock(&mq_lock);
 318
 319        inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
 320        if (IS_ERR(inode)) {
 321                error = PTR_ERR(inode);
 322                spin_lock(&mq_lock);
 323                ipc_ns->mq_queues_count--;
 324                goto out_unlock;
 325        }
 326
 327        put_ipc_ns(ipc_ns);
 328        dir->i_size += DIRENT_SIZE;
 329        dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 330
 331        d_instantiate(dentry, inode);
 332        dget(dentry);
 333        return 0;
 334out_unlock:
 335        spin_unlock(&mq_lock);
 336        if (ipc_ns)
 337                put_ipc_ns(ipc_ns);
 338        return error;
 339}
 340
 341static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
 342{
 343        struct inode *inode = dentry->d_inode;
 344
 345        dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 346        dir->i_size -= DIRENT_SIZE;
 347        drop_nlink(inode);
 348        dput(dentry);
 349        return 0;
 350}
 351
 352/*
 353*       This is routine for system read from queue file.
 354*       To avoid mess with doing here some sort of mq_receive we allow
 355*       to read only queue size & notification info (the only values
 356*       that are interesting from user point of view and aren't accessible
 357*       through std routines)
 358*/
 359static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
 360                                size_t count, loff_t *off)
 361{
 362        struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 363        char buffer[FILENT_SIZE];
 364        ssize_t ret;
 365
 366        spin_lock(&info->lock);
 367        snprintf(buffer, sizeof(buffer),
 368                        "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
 369                        info->qsize,
 370                        info->notify_owner ? info->notify.sigev_notify : 0,
 371                        (info->notify_owner &&
 372                         info->notify.sigev_notify == SIGEV_SIGNAL) ?
 373                                info->notify.sigev_signo : 0,
 374                        pid_vnr(info->notify_owner));
 375        spin_unlock(&info->lock);
 376        buffer[sizeof(buffer)-1] = '\0';
 377
 378        ret = simple_read_from_buffer(u_data, count, off, buffer,
 379                                strlen(buffer));
 380        if (ret <= 0)
 381                return ret;
 382
 383        filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
 384        return ret;
 385}
 386
 387static int mqueue_flush_file(struct file *filp, fl_owner_t id)
 388{
 389        struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 390
 391        spin_lock(&info->lock);
 392        if (task_tgid(current) == info->notify_owner)
 393                remove_notification(info);
 394
 395        spin_unlock(&info->lock);
 396        return 0;
 397}
 398
 399static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
 400{
 401        struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 402        int retval = 0;
 403
 404        poll_wait(filp, &info->wait_q, poll_tab);
 405
 406        spin_lock(&info->lock);
 407        if (info->attr.mq_curmsgs)
 408                retval = POLLIN | POLLRDNORM;
 409
 410        if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
 411                retval |= POLLOUT | POLLWRNORM;
 412        spin_unlock(&info->lock);
 413
 414        return retval;
 415}
 416
 417/* Adds current to info->e_wait_q[sr] before element with smaller prio */
 418static void wq_add(struct mqueue_inode_info *info, int sr,
 419                        struct ext_wait_queue *ewp)
 420{
 421        struct ext_wait_queue *walk;
 422
 423        ewp->task = current;
 424
 425        list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
 426                if (walk->task->static_prio <= current->static_prio) {
 427                        list_add_tail(&ewp->list, &walk->list);
 428                        return;
 429                }
 430        }
 431        list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
 432}
 433
 434/*
 435 * Puts current task to sleep. Caller must hold queue lock. After return
 436 * lock isn't held.
 437 * sr: SEND or RECV
 438 */
 439static int wq_sleep(struct mqueue_inode_info *info, int sr,
 440                    ktime_t *timeout, struct ext_wait_queue *ewp)
 441{
 442        int retval;
 443        signed long time;
 444
 445        wq_add(info, sr, ewp);
 446
 447        for (;;) {
 448                set_current_state(TASK_INTERRUPTIBLE);
 449
 450                spin_unlock(&info->lock);
 451                time = schedule_hrtimeout_range_clock(timeout, 0,
 452                        HRTIMER_MODE_ABS, CLOCK_REALTIME);
 453
 454                while (ewp->state == STATE_PENDING)
 455                        cpu_relax();
 456
 457                if (ewp->state == STATE_READY) {
 458                        retval = 0;
 459                        goto out;
 460                }
 461                spin_lock(&info->lock);
 462                if (ewp->state == STATE_READY) {
 463                        retval = 0;
 464                        goto out_unlock;
 465                }
 466                if (signal_pending(current)) {
 467                        retval = -ERESTARTSYS;
 468                        break;
 469                }
 470                if (time == 0) {
 471                        retval = -ETIMEDOUT;
 472                        break;
 473                }
 474        }
 475        list_del(&ewp->list);
 476out_unlock:
 477        spin_unlock(&info->lock);
 478out:
 479        return retval;
 480}
 481
 482/*
 483 * Returns waiting task that should be serviced first or NULL if none exists
 484 */
 485static struct ext_wait_queue *wq_get_first_waiter(
 486                struct mqueue_inode_info *info, int sr)
 487{
 488        struct list_head *ptr;
 489
 490        ptr = info->e_wait_q[sr].list.prev;
 491        if (ptr == &info->e_wait_q[sr].list)
 492                return NULL;
 493        return list_entry(ptr, struct ext_wait_queue, list);
 494}
 495
 496/* Auxiliary functions to manipulate messages' list */
 497static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
 498{
 499        int k;
 500
 501        k = info->attr.mq_curmsgs - 1;
 502        while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
 503                info->messages[k + 1] = info->messages[k];
 504                k--;
 505        }
 506        info->attr.mq_curmsgs++;
 507        info->qsize += ptr->m_ts;
 508        info->messages[k + 1] = ptr;
 509}
 510
 511static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
 512{
 513        info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
 514        return info->messages[info->attr.mq_curmsgs];
 515}
 516
 517static inline void set_cookie(struct sk_buff *skb, char code)
 518{
 519        ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
 520}
 521
 522/*
 523 * The next function is only to split too long sys_mq_timedsend
 524 */
 525static void __do_notify(struct mqueue_inode_info *info)
 526{
 527        /* notification
 528         * invoked when there is registered process and there isn't process
 529         * waiting synchronously for message AND state of queue changed from
 530         * empty to not empty. Here we are sure that no one is waiting
 531         * synchronously. */
 532        if (info->notify_owner &&
 533            info->attr.mq_curmsgs == 1) {
 534                struct siginfo sig_i;
 535                switch (info->notify.sigev_notify) {
 536                case SIGEV_NONE:
 537                        break;
 538                case SIGEV_SIGNAL:
 539                        /* sends signal */
 540
 541                        sig_i.si_signo = info->notify.sigev_signo;
 542                        sig_i.si_errno = 0;
 543                        sig_i.si_code = SI_MESGQ;
 544                        sig_i.si_value = info->notify.sigev_value;
 545                        /* map current pid/uid into info->owner's namespaces */
 546                        rcu_read_lock();
 547                        sig_i.si_pid = task_tgid_nr_ns(current,
 548                                                ns_of_pid(info->notify_owner));
 549                        sig_i.si_uid = user_ns_map_uid(info->user->user_ns,
 550                                                current_cred(), current_uid());
 551                        rcu_read_unlock();
 552
 553                        kill_pid_info(info->notify.sigev_signo,
 554                                      &sig_i, info->notify_owner);
 555                        break;
 556                case SIGEV_THREAD:
 557                        set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
 558                        netlink_sendskb(info->notify_sock, info->notify_cookie);
 559                        break;
 560                }
 561                /* after notification unregisters process */
 562                put_pid(info->notify_owner);
 563                info->notify_owner = NULL;
 564        }
 565        wake_up(&info->wait_q);
 566}
 567
 568static int prepare_timeout(const struct timespec __user *u_abs_timeout,
 569                           ktime_t *expires, struct timespec *ts)
 570{
 571        if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec)))
 572                return -EFAULT;
 573        if (!timespec_valid(ts))
 574                return -EINVAL;
 575
 576        *expires = timespec_to_ktime(*ts);
 577        return 0;
 578}
 579
 580static void remove_notification(struct mqueue_inode_info *info)
 581{
 582        if (info->notify_owner != NULL &&
 583            info->notify.sigev_notify == SIGEV_THREAD) {
 584                set_cookie(info->notify_cookie, NOTIFY_REMOVED);
 585                netlink_sendskb(info->notify_sock, info->notify_cookie);
 586        }
 587        put_pid(info->notify_owner);
 588        info->notify_owner = NULL;
 589}
 590
 591static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
 592{
 593        if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
 594                return 0;
 595        if (capable(CAP_SYS_RESOURCE)) {
 596                if (attr->mq_maxmsg > HARD_MSGMAX)
 597                        return 0;
 598        } else {
 599                if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
 600                                attr->mq_msgsize > ipc_ns->mq_msgsize_max)
 601                        return 0;
 602        }
 603        /* check for overflow */
 604        if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
 605                return 0;
 606        if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize
 607            + sizeof (struct msg_msg *))) <
 608            (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
 609                return 0;
 610        return 1;
 611}
 612
 613/*
 614 * Invoked when creating a new queue via sys_mq_open
 615 */
 616static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir,
 617                        struct dentry *dentry, int oflag, umode_t mode,
 618                        struct mq_attr *attr)
 619{
 620        const struct cred *cred = current_cred();
 621        struct file *result;
 622        int ret;
 623
 624        if (attr) {
 625                if (!mq_attr_ok(ipc_ns, attr)) {
 626                        ret = -EINVAL;
 627                        goto out;
 628                }
 629                /* store for use during create */
 630                dentry->d_fsdata = attr;
 631        }
 632
 633        mode &= ~current_umask();
 634        ret = mnt_want_write(ipc_ns->mq_mnt);
 635        if (ret)
 636                goto out;
 637        ret = vfs_create(dir->d_inode, dentry, mode, NULL);
 638        dentry->d_fsdata = NULL;
 639        if (ret)
 640                goto out_drop_write;
 641
 642        result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
 643        /*
 644         * dentry_open() took a persistent mnt_want_write(),
 645         * so we can now drop this one.
 646         */
 647        mnt_drop_write(ipc_ns->mq_mnt);
 648        return result;
 649
 650out_drop_write:
 651        mnt_drop_write(ipc_ns->mq_mnt);
 652out:
 653        dput(dentry);
 654        mntput(ipc_ns->mq_mnt);
 655        return ERR_PTR(ret);
 656}
 657
 658/* Opens existing queue */
 659static struct file *do_open(struct ipc_namespace *ipc_ns,
 660                                struct dentry *dentry, int oflag)
 661{
 662        int ret;
 663        const struct cred *cred = current_cred();
 664
 665        static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
 666                                                  MAY_READ | MAY_WRITE };
 667
 668        if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
 669                ret = -EINVAL;
 670                goto err;
 671        }
 672
 673        if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
 674                ret = -EACCES;
 675                goto err;
 676        }
 677
 678        return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
 679
 680err:
 681        dput(dentry);
 682        mntput(ipc_ns->mq_mnt);
 683        return ERR_PTR(ret);
 684}
 685
 686SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
 687                struct mq_attr __user *, u_attr)
 688{
 689        struct dentry *dentry;
 690        struct file *filp;
 691        char *name;
 692        struct mq_attr attr;
 693        int fd, error;
 694        struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
 695
 696        if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
 697                return -EFAULT;
 698
 699        audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
 700
 701        if (IS_ERR(name = getname(u_name)))
 702                return PTR_ERR(name);
 703
 704        fd = get_unused_fd_flags(O_CLOEXEC);
 705        if (fd < 0)
 706                goto out_putname;
 707
 708        mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 709        dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
 710        if (IS_ERR(dentry)) {
 711                error = PTR_ERR(dentry);
 712                goto out_putfd;
 713        }
 714        mntget(ipc_ns->mq_mnt);
 715
 716        if (oflag & O_CREAT) {
 717                if (dentry->d_inode) {  /* entry already exists */
 718                        audit_inode(name, dentry);
 719                        if (oflag & O_EXCL) {
 720                                error = -EEXIST;
 721                                goto out;
 722                        }
 723                        filp = do_open(ipc_ns, dentry, oflag);
 724                } else {
 725                        filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root,
 726                                                dentry, oflag, mode,
 727                                                u_attr ? &attr : NULL);
 728                }
 729        } else {
 730                if (!dentry->d_inode) {
 731                        error = -ENOENT;
 732                        goto out;
 733                }
 734                audit_inode(name, dentry);
 735                filp = do_open(ipc_ns, dentry, oflag);
 736        }
 737
 738        if (IS_ERR(filp)) {
 739                error = PTR_ERR(filp);
 740                goto out_putfd;
 741        }
 742
 743        fd_install(fd, filp);
 744        goto out_upsem;
 745
 746out:
 747        dput(dentry);
 748        mntput(ipc_ns->mq_mnt);
 749out_putfd:
 750        put_unused_fd(fd);
 751        fd = error;
 752out_upsem:
 753        mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 754out_putname:
 755        putname(name);
 756        return fd;
 757}
 758
 759SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
 760{
 761        int err;
 762        char *name;
 763        struct dentry *dentry;
 764        struct inode *inode = NULL;
 765        struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
 766
 767        name = getname(u_name);
 768        if (IS_ERR(name))
 769                return PTR_ERR(name);
 770
 771        mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
 772                        I_MUTEX_PARENT);
 773        dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
 774        if (IS_ERR(dentry)) {
 775                err = PTR_ERR(dentry);
 776                goto out_unlock;
 777        }
 778
 779        if (!dentry->d_inode) {
 780                err = -ENOENT;
 781                goto out_err;
 782        }
 783
 784        inode = dentry->d_inode;
 785        if (inode)
 786                ihold(inode);
 787        err = mnt_want_write(ipc_ns->mq_mnt);
 788        if (err)
 789                goto out_err;
 790        err = vfs_unlink(dentry->d_parent->d_inode, dentry);
 791        mnt_drop_write(ipc_ns->mq_mnt);
 792out_err:
 793        dput(dentry);
 794
 795out_unlock:
 796        mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 797        putname(name);
 798        if (inode)
 799                iput(inode);
 800
 801        return err;
 802}
 803
 804/* Pipelined send and receive functions.
 805 *
 806 * If a receiver finds no waiting message, then it registers itself in the
 807 * list of waiting receivers. A sender checks that list before adding the new
 808 * message into the message array. If there is a waiting receiver, then it
 809 * bypasses the message array and directly hands the message over to the
 810 * receiver.
 811 * The receiver accepts the message and returns without grabbing the queue
 812 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
 813 * are necessary. The same algorithm is used for sysv semaphores, see
 814 * ipc/sem.c for more details.
 815 *
 816 * The same algorithm is used for senders.
 817 */
 818
 819/* pipelined_send() - send a message directly to the task waiting in
 820 * sys_mq_timedreceive() (without inserting message into a queue).
 821 */
 822static inline void pipelined_send(struct mqueue_inode_info *info,
 823                                  struct msg_msg *message,
 824                                  struct ext_wait_queue *receiver)
 825{
 826        receiver->msg = message;
 827        list_del(&receiver->list);
 828        receiver->state = STATE_PENDING;
 829        wake_up_process(receiver->task);
 830        smp_wmb();
 831        receiver->state = STATE_READY;
 832}
 833
 834/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
 835 * gets its message and put to the queue (we have one free place for sure). */
 836static inline void pipelined_receive(struct mqueue_inode_info *info)
 837{
 838        struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
 839
 840        if (!sender) {
 841                /* for poll */
 842                wake_up_interruptible(&info->wait_q);
 843                return;
 844        }
 845        msg_insert(sender->msg, info);
 846        list_del(&sender->list);
 847        sender->state = STATE_PENDING;
 848        wake_up_process(sender->task);
 849        smp_wmb();
 850        sender->state = STATE_READY;
 851}
 852
 853SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
 854                size_t, msg_len, unsigned int, msg_prio,
 855                const struct timespec __user *, u_abs_timeout)
 856{
 857        struct file *filp;
 858        struct inode *inode;
 859        struct ext_wait_queue wait;
 860        struct ext_wait_queue *receiver;
 861        struct msg_msg *msg_ptr;
 862        struct mqueue_inode_info *info;
 863        ktime_t expires, *timeout = NULL;
 864        struct timespec ts;
 865        int ret;
 866
 867        if (u_abs_timeout) {
 868                int res = prepare_timeout(u_abs_timeout, &expires, &ts);
 869                if (res)
 870                        return res;
 871                timeout = &expires;
 872        }
 873
 874        if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
 875                return -EINVAL;
 876
 877        audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL);
 878
 879        filp = fget(mqdes);
 880        if (unlikely(!filp)) {
 881                ret = -EBADF;
 882                goto out;
 883        }
 884
 885        inode = filp->f_path.dentry->d_inode;
 886        if (unlikely(filp->f_op != &mqueue_file_operations)) {
 887                ret = -EBADF;
 888                goto out_fput;
 889        }
 890        info = MQUEUE_I(inode);
 891        audit_inode(NULL, filp->f_path.dentry);
 892
 893        if (unlikely(!(filp->f_mode & FMODE_WRITE))) {
 894                ret = -EBADF;
 895                goto out_fput;
 896        }
 897
 898        if (unlikely(msg_len > info->attr.mq_msgsize)) {
 899                ret = -EMSGSIZE;
 900                goto out_fput;
 901        }
 902
 903        /* First try to allocate memory, before doing anything with
 904         * existing queues. */
 905        msg_ptr = load_msg(u_msg_ptr, msg_len);
 906        if (IS_ERR(msg_ptr)) {
 907                ret = PTR_ERR(msg_ptr);
 908                goto out_fput;
 909        }
 910        msg_ptr->m_ts = msg_len;
 911        msg_ptr->m_type = msg_prio;
 912
 913        spin_lock(&info->lock);
 914
 915        if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
 916                if (filp->f_flags & O_NONBLOCK) {
 917                        spin_unlock(&info->lock);
 918                        ret = -EAGAIN;
 919                } else {
 920                        wait.task = current;
 921                        wait.msg = (void *) msg_ptr;
 922                        wait.state = STATE_NONE;
 923                        ret = wq_sleep(info, SEND, timeout, &wait);
 924                }
 925                if (ret < 0)
 926                        free_msg(msg_ptr);
 927        } else {
 928                receiver = wq_get_first_waiter(info, RECV);
 929                if (receiver) {
 930                        pipelined_send(info, msg_ptr, receiver);
 931                } else {
 932                        /* adds message to the queue */
 933                        msg_insert(msg_ptr, info);
 934                        __do_notify(info);
 935                }
 936                inode->i_atime = inode->i_mtime = inode->i_ctime =
 937                                CURRENT_TIME;
 938                spin_unlock(&info->lock);
 939                ret = 0;
 940        }
 941out_fput:
 942        fput(filp);
 943out:
 944        return ret;
 945}
 946
 947SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
 948                size_t, msg_len, unsigned int __user *, u_msg_prio,
 949                const struct timespec __user *, u_abs_timeout)
 950{
 951        ssize_t ret;
 952        struct msg_msg *msg_ptr;
 953        struct file *filp;
 954        struct inode *inode;
 955        struct mqueue_inode_info *info;
 956        struct ext_wait_queue wait;
 957        ktime_t expires, *timeout = NULL;
 958        struct timespec ts;
 959
 960        if (u_abs_timeout) {
 961                int res = prepare_timeout(u_abs_timeout, &expires, &ts);
 962                if (res)
 963                        return res;
 964                timeout = &expires;
 965        }
 966
 967        audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
 968
 969        filp = fget(mqdes);
 970        if (unlikely(!filp)) {
 971                ret = -EBADF;
 972                goto out;
 973        }
 974
 975        inode = filp->f_path.dentry->d_inode;
 976        if (unlikely(filp->f_op != &mqueue_file_operations)) {
 977                ret = -EBADF;
 978                goto out_fput;
 979        }
 980        info = MQUEUE_I(inode);
 981        audit_inode(NULL, filp->f_path.dentry);
 982
 983        if (unlikely(!(filp->f_mode & FMODE_READ))) {
 984                ret = -EBADF;
 985                goto out_fput;
 986        }
 987
 988        /* checks if buffer is big enough */
 989        if (unlikely(msg_len < info->attr.mq_msgsize)) {
 990                ret = -EMSGSIZE;
 991                goto out_fput;
 992        }
 993
 994        spin_lock(&info->lock);
 995        if (info->attr.mq_curmsgs == 0) {
 996                if (filp->f_flags & O_NONBLOCK) {
 997                        spin_unlock(&info->lock);
 998                        ret = -EAGAIN;
 999                } else {
1000                        wait.task = current;
1001                        wait.state = STATE_NONE;
1002                        ret = wq_sleep(info, RECV, timeout, &wait);
1003                        msg_ptr = wait.msg;
1004                }
1005        } else {
1006                msg_ptr = msg_get(info);
1007
1008                inode->i_atime = inode->i_mtime = inode->i_ctime =
1009                                CURRENT_TIME;
1010
1011                /* There is now free space in queue. */
1012                pipelined_receive(info);
1013                spin_unlock(&info->lock);
1014                ret = 0;
1015        }
1016        if (ret == 0) {
1017                ret = msg_ptr->m_ts;
1018
1019                if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1020                        store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1021                        ret = -EFAULT;
1022                }
1023                free_msg(msg_ptr);
1024        }
1025out_fput:
1026        fput(filp);
1027out:
1028        return ret;
1029}
1030
1031/*
1032 * Notes: the case when user wants us to deregister (with NULL as pointer)
1033 * and he isn't currently owner of notification, will be silently discarded.
1034 * It isn't explicitly defined in the POSIX.
1035 */
1036SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1037                const struct sigevent __user *, u_notification)
1038{
1039        int ret;
1040        struct file *filp;
1041        struct sock *sock;
1042        struct inode *inode;
1043        struct sigevent notification;
1044        struct mqueue_inode_info *info;
1045        struct sk_buff *nc;
1046
1047        if (u_notification) {
1048                if (copy_from_user(&notification, u_notification,
1049                                        sizeof(struct sigevent)))
1050                        return -EFAULT;
1051        }
1052
1053        audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1054
1055        nc = NULL;
1056        sock = NULL;
1057        if (u_notification != NULL) {
1058                if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1059                             notification.sigev_notify != SIGEV_SIGNAL &&
1060                             notification.sigev_notify != SIGEV_THREAD))
1061                        return -EINVAL;
1062                if (notification.sigev_notify == SIGEV_SIGNAL &&
1063                        !valid_signal(notification.sigev_signo)) {
1064                        return -EINVAL;
1065                }
1066                if (notification.sigev_notify == SIGEV_THREAD) {
1067                        long timeo;
1068
1069                        /* create the notify skb */
1070                        nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1071                        if (!nc) {
1072                                ret = -ENOMEM;
1073                                goto out;
1074                        }
1075                        if (copy_from_user(nc->data,
1076                                        notification.sigev_value.sival_ptr,
1077                                        NOTIFY_COOKIE_LEN)) {
1078                                ret = -EFAULT;
1079                                goto out;
1080                        }
1081
1082                        /* TODO: add a header? */
1083                        skb_put(nc, NOTIFY_COOKIE_LEN);
1084                        /* and attach it to the socket */
1085retry:
1086                        filp = fget(notification.sigev_signo);
1087                        if (!filp) {
1088                                ret = -EBADF;
1089                                goto out;
1090                        }
1091                        sock = netlink_getsockbyfilp(filp);
1092                        fput(filp);
1093                        if (IS_ERR(sock)) {
1094                                ret = PTR_ERR(sock);
1095                                sock = NULL;
1096                                goto out;
1097                        }
1098
1099                        timeo = MAX_SCHEDULE_TIMEOUT;
1100                        ret = netlink_attachskb(sock, nc, &timeo, NULL);
1101                        if (ret == 1)
1102                                goto retry;
1103                        if (ret) {
1104                                sock = NULL;
1105                                nc = NULL;
1106                                goto out;
1107                        }
1108                }
1109        }
1110
1111        filp = fget(mqdes);
1112        if (!filp) {
1113                ret = -EBADF;
1114                goto out;
1115        }
1116
1117        inode = filp->f_path.dentry->d_inode;
1118        if (unlikely(filp->f_op != &mqueue_file_operations)) {
1119                ret = -EBADF;
1120                goto out_fput;
1121        }
1122        info = MQUEUE_I(inode);
1123
1124        ret = 0;
1125        spin_lock(&info->lock);
1126        if (u_notification == NULL) {
1127                if (info->notify_owner == task_tgid(current)) {
1128                        remove_notification(info);
1129                        inode->i_atime = inode->i_ctime = CURRENT_TIME;
1130                }
1131        } else if (info->notify_owner != NULL) {
1132                ret = -EBUSY;
1133        } else {
1134                switch (notification.sigev_notify) {
1135                case SIGEV_NONE:
1136                        info->notify.sigev_notify = SIGEV_NONE;
1137                        break;
1138                case SIGEV_THREAD:
1139                        info->notify_sock = sock;
1140                        info->notify_cookie = nc;
1141                        sock = NULL;
1142                        nc = NULL;
1143                        info->notify.sigev_notify = SIGEV_THREAD;
1144                        break;
1145                case SIGEV_SIGNAL:
1146                        info->notify.sigev_signo = notification.sigev_signo;
1147                        info->notify.sigev_value = notification.sigev_value;
1148                        info->notify.sigev_notify = SIGEV_SIGNAL;
1149                        break;
1150                }
1151
1152                info->notify_owner = get_pid(task_tgid(current));
1153                inode->i_atime = inode->i_ctime = CURRENT_TIME;
1154        }
1155        spin_unlock(&info->lock);
1156out_fput:
1157        fput(filp);
1158out:
1159        if (sock) {
1160                netlink_detachskb(sock, nc);
1161        } else if (nc) {
1162                dev_kfree_skb(nc);
1163        }
1164        return ret;
1165}
1166
1167SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1168                const struct mq_attr __user *, u_mqstat,
1169                struct mq_attr __user *, u_omqstat)
1170{
1171        int ret;
1172        struct mq_attr mqstat, omqstat;
1173        struct file *filp;
1174        struct inode *inode;
1175        struct mqueue_inode_info *info;
1176
1177        if (u_mqstat != NULL) {
1178                if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1179                        return -EFAULT;
1180                if (mqstat.mq_flags & (~O_NONBLOCK))
1181                        return -EINVAL;
1182        }
1183
1184        filp = fget(mqdes);
1185        if (!filp) {
1186                ret = -EBADF;
1187                goto out;
1188        }
1189
1190        inode = filp->f_path.dentry->d_inode;
1191        if (unlikely(filp->f_op != &mqueue_file_operations)) {
1192                ret = -EBADF;
1193                goto out_fput;
1194        }
1195        info = MQUEUE_I(inode);
1196
1197        spin_lock(&info->lock);
1198
1199        omqstat = info->attr;
1200        omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1201        if (u_mqstat) {
1202                audit_mq_getsetattr(mqdes, &mqstat);
1203                spin_lock(&filp->f_lock);
1204                if (mqstat.mq_flags & O_NONBLOCK)
1205                        filp->f_flags |= O_NONBLOCK;
1206                else
1207                        filp->f_flags &= ~O_NONBLOCK;
1208                spin_unlock(&filp->f_lock);
1209
1210                inode->i_atime = inode->i_ctime = CURRENT_TIME;
1211        }
1212
1213        spin_unlock(&info->lock);
1214
1215        ret = 0;
1216        if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1217                                                sizeof(struct mq_attr)))
1218                ret = -EFAULT;
1219
1220out_fput:
1221        fput(filp);
1222out:
1223        return ret;
1224}
1225
1226static const struct inode_operations mqueue_dir_inode_operations = {
1227        .lookup = simple_lookup,
1228        .create = mqueue_create,
1229        .unlink = mqueue_unlink,
1230};
1231
1232static const struct file_operations mqueue_file_operations = {
1233        .flush = mqueue_flush_file,
1234        .poll = mqueue_poll_file,
1235        .read = mqueue_read_file,
1236        .llseek = default_llseek,
1237};
1238
1239static const struct super_operations mqueue_super_ops = {
1240        .alloc_inode = mqueue_alloc_inode,
1241        .destroy_inode = mqueue_destroy_inode,
1242        .evict_inode = mqueue_evict_inode,
1243        .statfs = simple_statfs,
1244};
1245
1246static struct file_system_type mqueue_fs_type = {
1247        .name = "mqueue",
1248        .mount = mqueue_mount,
1249        .kill_sb = kill_litter_super,
1250};
1251
1252int mq_init_ns(struct ipc_namespace *ns)
1253{
1254        ns->mq_queues_count  = 0;
1255        ns->mq_queues_max    = DFLT_QUEUESMAX;
1256        ns->mq_msg_max       = DFLT_MSGMAX;
1257        ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1258
1259        ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1260        if (IS_ERR(ns->mq_mnt)) {
1261                int err = PTR_ERR(ns->mq_mnt);
1262                ns->mq_mnt = NULL;
1263                return err;
1264        }
1265        return 0;
1266}
1267
1268void mq_clear_sbinfo(struct ipc_namespace *ns)
1269{
1270        ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1271}
1272
1273void mq_put_mnt(struct ipc_namespace *ns)
1274{
1275        kern_unmount(ns->mq_mnt);
1276}
1277
1278static int __init init_mqueue_fs(void)
1279{
1280        int error;
1281
1282        mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1283                                sizeof(struct mqueue_inode_info), 0,
1284                                SLAB_HWCACHE_ALIGN, init_once);
1285        if (mqueue_inode_cachep == NULL)
1286                return -ENOMEM;
1287
1288        /* ignore failures - they are not fatal */
1289        mq_sysctl_table = mq_register_sysctl_table();
1290
1291        error = register_filesystem(&mqueue_fs_type);
1292        if (error)
1293                goto out_sysctl;
1294
1295        spin_lock_init(&mq_lock);
1296
1297        error = mq_init_ns(&init_ipc_ns);
1298        if (error)
1299                goto out_filesystem;
1300
1301        return 0;
1302
1303out_filesystem:
1304        unregister_filesystem(&mqueue_fs_type);
1305out_sysctl:
1306        if (mq_sysctl_table)
1307                unregister_sysctl_table(mq_sysctl_table);
1308        kmem_cache_destroy(mqueue_inode_cachep);
1309        return error;
1310}
1311
1312__initcall(init_mqueue_fs);
1313