linux/ipc/mqueue.c
<<
>>
Prefs
   1/*
   2 * POSIX message queues filesystem for Linux.
   3 *
   4 * Copyright (C) 2003,2004  Krzysztof Benedyczak    (golbi@mat.uni.torun.pl)
   5 *                          Michal Wronski          (michal.wronski@gmail.com)
   6 *
   7 * Spinlocks:               Mohamed Abbas           (abbas.mohamed@intel.com)
   8 * Lockless receive & send, fd based notify:
   9 *                          Manfred Spraul          (manfred@colorfullife.com)
  10 *
  11 * Audit:                   George Wilson           (ltcgcw@us.ibm.com)
  12 *
  13 * This file is released under the GPL.
  14 */
  15
  16#include <linux/capability.h>
  17#include <linux/init.h>
  18#include <linux/pagemap.h>
  19#include <linux/file.h>
  20#include <linux/mount.h>
  21#include <linux/namei.h>
  22#include <linux/sysctl.h>
  23#include <linux/poll.h>
  24#include <linux/mqueue.h>
  25#include <linux/msg.h>
  26#include <linux/skbuff.h>
  27#include <linux/vmalloc.h>
  28#include <linux/netlink.h>
  29#include <linux/syscalls.h>
  30#include <linux/audit.h>
  31#include <linux/signal.h>
  32#include <linux/mutex.h>
  33#include <linux/nsproxy.h>
  34#include <linux/pid.h>
  35#include <linux/ipc_namespace.h>
  36#include <linux/user_namespace.h>
  37#include <linux/slab.h>
  38
  39#include <net/sock.h>
  40#include "util.h"
  41
  42#define MQUEUE_MAGIC    0x19800202
  43#define DIRENT_SIZE     20
  44#define FILENT_SIZE     80
  45
  46#define SEND            0
  47#define RECV            1
  48
  49#define STATE_NONE      0
  50#define STATE_PENDING   1
  51#define STATE_READY     2
  52
  53struct posix_msg_tree_node {
  54        struct rb_node          rb_node;
  55        struct list_head        msg_list;
  56        int                     priority;
  57};
  58
  59struct ext_wait_queue {         /* queue of sleeping tasks */
  60        struct task_struct *task;
  61        struct list_head list;
  62        struct msg_msg *msg;    /* ptr of loaded message */
  63        int state;              /* one of STATE_* values */
  64};
  65
  66struct mqueue_inode_info {
  67        spinlock_t lock;
  68        struct inode vfs_inode;
  69        wait_queue_head_t wait_q;
  70
  71        struct rb_root msg_tree;
  72        struct posix_msg_tree_node *node_cache;
  73        struct mq_attr attr;
  74
  75        struct sigevent notify;
  76        struct pid* notify_owner;
  77        struct user_namespace *notify_user_ns;
  78        struct user_struct *user;       /* user who created, for accounting */
  79        struct sock *notify_sock;
  80        struct sk_buff *notify_cookie;
  81
  82        /* for tasks waiting for free space and messages, respectively */
  83        struct ext_wait_queue e_wait_q[2];
  84
  85        unsigned long qsize; /* size of queue in memory (sum of all msgs) */
  86};
  87
  88static const struct inode_operations mqueue_dir_inode_operations;
  89static const struct file_operations mqueue_file_operations;
  90static const struct super_operations mqueue_super_ops;
  91static void remove_notification(struct mqueue_inode_info *info);
  92
  93static struct kmem_cache *mqueue_inode_cachep;
  94
  95static struct ctl_table_header * mq_sysctl_table;
  96
  97static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
  98{
  99        return container_of(inode, struct mqueue_inode_info, vfs_inode);
 100}
 101
 102/*
 103 * This routine should be called with the mq_lock held.
 104 */
 105static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
 106{
 107        return get_ipc_ns(inode->i_sb->s_fs_info);
 108}
 109
 110static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
 111{
 112        struct ipc_namespace *ns;
 113
 114        spin_lock(&mq_lock);
 115        ns = __get_ns_from_inode(inode);
 116        spin_unlock(&mq_lock);
 117        return ns;
 118}
 119
 120/* Auxiliary functions to manipulate messages' list */
 121static int msg_insert(struct msg_msg *msg, struct mqueue_inode_info *info)
 122{
 123        struct rb_node **p, *parent = NULL;
 124        struct posix_msg_tree_node *leaf;
 125
 126        p = &info->msg_tree.rb_node;
 127        while (*p) {
 128                parent = *p;
 129                leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
 130
 131                if (likely(leaf->priority == msg->m_type))
 132                        goto insert_msg;
 133                else if (msg->m_type < leaf->priority)
 134                        p = &(*p)->rb_left;
 135                else
 136                        p = &(*p)->rb_right;
 137        }
 138        if (info->node_cache) {
 139                leaf = info->node_cache;
 140                info->node_cache = NULL;
 141        } else {
 142                leaf = kmalloc(sizeof(*leaf), GFP_ATOMIC);
 143                if (!leaf)
 144                        return -ENOMEM;
 145                INIT_LIST_HEAD(&leaf->msg_list);
 146                info->qsize += sizeof(*leaf);
 147        }
 148        leaf->priority = msg->m_type;
 149        rb_link_node(&leaf->rb_node, parent, p);
 150        rb_insert_color(&leaf->rb_node, &info->msg_tree);
 151insert_msg:
 152        info->attr.mq_curmsgs++;
 153        info->qsize += msg->m_ts;
 154        list_add_tail(&msg->m_list, &leaf->msg_list);
 155        return 0;
 156}
 157
 158static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
 159{
 160        struct rb_node **p, *parent = NULL;
 161        struct posix_msg_tree_node *leaf;
 162        struct msg_msg *msg;
 163
 164try_again:
 165        p = &info->msg_tree.rb_node;
 166        while (*p) {
 167                parent = *p;
 168                /*
 169                 * During insert, low priorities go to the left and high to the
 170                 * right.  On receive, we want the highest priorities first, so
 171                 * walk all the way to the right.
 172                 */
 173                p = &(*p)->rb_right;
 174        }
 175        if (!parent) {
 176                if (info->attr.mq_curmsgs) {
 177                        pr_warn_once("Inconsistency in POSIX message queue, "
 178                                     "no tree element, but supposedly messages "
 179                                     "should exist!\n");
 180                        info->attr.mq_curmsgs = 0;
 181                }
 182                return NULL;
 183        }
 184        leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
 185        if (unlikely(list_empty(&leaf->msg_list))) {
 186                pr_warn_once("Inconsistency in POSIX message queue, "
 187                             "empty leaf node but we haven't implemented "
 188                             "lazy leaf delete!\n");
 189                rb_erase(&leaf->rb_node, &info->msg_tree);
 190                if (info->node_cache) {
 191                        info->qsize -= sizeof(*leaf);
 192                        kfree(leaf);
 193                } else {
 194                        info->node_cache = leaf;
 195                }
 196                goto try_again;
 197        } else {
 198                msg = list_first_entry(&leaf->msg_list,
 199                                       struct msg_msg, m_list);
 200                list_del(&msg->m_list);
 201                if (list_empty(&leaf->msg_list)) {
 202                        rb_erase(&leaf->rb_node, &info->msg_tree);
 203                        if (info->node_cache) {
 204                                info->qsize -= sizeof(*leaf);
 205                                kfree(leaf);
 206                        } else {
 207                                info->node_cache = leaf;
 208                        }
 209                }
 210        }
 211        info->attr.mq_curmsgs--;
 212        info->qsize -= msg->m_ts;
 213        return msg;
 214}
 215
 216static struct inode *mqueue_get_inode(struct super_block *sb,
 217                struct ipc_namespace *ipc_ns, umode_t mode,
 218                struct mq_attr *attr)
 219{
 220        struct user_struct *u = current_user();
 221        struct inode *inode;
 222        int ret = -ENOMEM;
 223
 224        inode = new_inode(sb);
 225        if (!inode)
 226                goto err;
 227
 228        inode->i_ino = get_next_ino();
 229        inode->i_mode = mode;
 230        inode->i_uid = current_fsuid();
 231        inode->i_gid = current_fsgid();
 232        inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME;
 233
 234        if (S_ISREG(mode)) {
 235                struct mqueue_inode_info *info;
 236                unsigned long mq_bytes, mq_treesize;
 237
 238                inode->i_fop = &mqueue_file_operations;
 239                inode->i_size = FILENT_SIZE;
 240                /* mqueue specific info */
 241                info = MQUEUE_I(inode);
 242                spin_lock_init(&info->lock);
 243                init_waitqueue_head(&info->wait_q);
 244                INIT_LIST_HEAD(&info->e_wait_q[0].list);
 245                INIT_LIST_HEAD(&info->e_wait_q[1].list);
 246                info->notify_owner = NULL;
 247                info->notify_user_ns = NULL;
 248                info->qsize = 0;
 249                info->user = NULL;      /* set when all is ok */
 250                info->msg_tree = RB_ROOT;
 251                info->node_cache = NULL;
 252                memset(&info->attr, 0, sizeof(info->attr));
 253                info->attr.mq_maxmsg = min(ipc_ns->mq_msg_max,
 254                                           ipc_ns->mq_msg_default);
 255                info->attr.mq_msgsize = min(ipc_ns->mq_msgsize_max,
 256                                            ipc_ns->mq_msgsize_default);
 257                if (attr) {
 258                        info->attr.mq_maxmsg = attr->mq_maxmsg;
 259                        info->attr.mq_msgsize = attr->mq_msgsize;
 260                }
 261                /*
 262                 * We used to allocate a static array of pointers and account
 263                 * the size of that array as well as one msg_msg struct per
 264                 * possible message into the queue size. That's no longer
 265                 * accurate as the queue is now an rbtree and will grow and
 266                 * shrink depending on usage patterns.  We can, however, still
 267                 * account one msg_msg struct per message, but the nodes are
 268                 * allocated depending on priority usage, and most programs
 269                 * only use one, or a handful, of priorities.  However, since
 270                 * this is pinned memory, we need to assume worst case, so
 271                 * that means the min(mq_maxmsg, max_priorities) * struct
 272                 * posix_msg_tree_node.
 273                 */
 274                mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
 275                        min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
 276                        sizeof(struct posix_msg_tree_node);
 277
 278                mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
 279                                          info->attr.mq_msgsize);
 280
 281                spin_lock(&mq_lock);
 282                if (u->mq_bytes + mq_bytes < u->mq_bytes ||
 283                    u->mq_bytes + mq_bytes > rlimit(RLIMIT_MSGQUEUE)) {
 284                        spin_unlock(&mq_lock);
 285                        /* mqueue_evict_inode() releases info->messages */
 286                        ret = -EMFILE;
 287                        goto out_inode;
 288                }
 289                u->mq_bytes += mq_bytes;
 290                spin_unlock(&mq_lock);
 291
 292                /* all is ok */
 293                info->user = get_uid(u);
 294        } else if (S_ISDIR(mode)) {
 295                inc_nlink(inode);
 296                /* Some things misbehave if size == 0 on a directory */
 297                inode->i_size = 2 * DIRENT_SIZE;
 298                inode->i_op = &mqueue_dir_inode_operations;
 299                inode->i_fop = &simple_dir_operations;
 300        }
 301
 302        return inode;
 303out_inode:
 304        iput(inode);
 305err:
 306        return ERR_PTR(ret);
 307}
 308
 309static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
 310{
 311        struct inode *inode;
 312        struct ipc_namespace *ns = data;
 313
 314        sb->s_blocksize = PAGE_CACHE_SIZE;
 315        sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 316        sb->s_magic = MQUEUE_MAGIC;
 317        sb->s_op = &mqueue_super_ops;
 318
 319        inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
 320        if (IS_ERR(inode))
 321                return PTR_ERR(inode);
 322
 323        sb->s_root = d_make_root(inode);
 324        if (!sb->s_root)
 325                return -ENOMEM;
 326        return 0;
 327}
 328
 329static struct dentry *mqueue_mount(struct file_system_type *fs_type,
 330                         int flags, const char *dev_name,
 331                         void *data)
 332{
 333        if (!(flags & MS_KERNMOUNT)) {
 334                struct ipc_namespace *ns = current->nsproxy->ipc_ns;
 335                /* Don't allow mounting unless the caller has CAP_SYS_ADMIN
 336                 * over the ipc namespace.
 337                 */
 338                if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN))
 339                        return ERR_PTR(-EPERM);
 340
 341                data = ns;
 342        }
 343        return mount_ns(fs_type, flags, data, mqueue_fill_super);
 344}
 345
 346static void init_once(void *foo)
 347{
 348        struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
 349
 350        inode_init_once(&p->vfs_inode);
 351}
 352
 353static struct inode *mqueue_alloc_inode(struct super_block *sb)
 354{
 355        struct mqueue_inode_info *ei;
 356
 357        ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
 358        if (!ei)
 359                return NULL;
 360        return &ei->vfs_inode;
 361}
 362
 363static void mqueue_i_callback(struct rcu_head *head)
 364{
 365        struct inode *inode = container_of(head, struct inode, i_rcu);
 366        kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
 367}
 368
 369static void mqueue_destroy_inode(struct inode *inode)
 370{
 371        call_rcu(&inode->i_rcu, mqueue_i_callback);
 372}
 373
 374static void mqueue_evict_inode(struct inode *inode)
 375{
 376        struct mqueue_inode_info *info;
 377        struct user_struct *user;
 378        unsigned long mq_bytes, mq_treesize;
 379        struct ipc_namespace *ipc_ns;
 380        struct msg_msg *msg;
 381
 382        clear_inode(inode);
 383
 384        if (S_ISDIR(inode->i_mode))
 385                return;
 386
 387        ipc_ns = get_ns_from_inode(inode);
 388        info = MQUEUE_I(inode);
 389        spin_lock(&info->lock);
 390        while ((msg = msg_get(info)) != NULL)
 391                free_msg(msg);
 392        kfree(info->node_cache);
 393        spin_unlock(&info->lock);
 394
 395        /* Total amount of bytes accounted for the mqueue */
 396        mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
 397                min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
 398                sizeof(struct posix_msg_tree_node);
 399
 400        mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
 401                                  info->attr.mq_msgsize);
 402
 403        user = info->user;
 404        if (user) {
 405                spin_lock(&mq_lock);
 406                user->mq_bytes -= mq_bytes;
 407                /*
 408                 * get_ns_from_inode() ensures that the
 409                 * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
 410                 * to which we now hold a reference, or it is NULL.
 411                 * We can't put it here under mq_lock, though.
 412                 */
 413                if (ipc_ns)
 414                        ipc_ns->mq_queues_count--;
 415                spin_unlock(&mq_lock);
 416                free_uid(user);
 417        }
 418        if (ipc_ns)
 419                put_ipc_ns(ipc_ns);
 420}
 421
 422static int mqueue_create(struct inode *dir, struct dentry *dentry,
 423                                umode_t mode, bool excl)
 424{
 425        struct inode *inode;
 426        struct mq_attr *attr = dentry->d_fsdata;
 427        int error;
 428        struct ipc_namespace *ipc_ns;
 429
 430        spin_lock(&mq_lock);
 431        ipc_ns = __get_ns_from_inode(dir);
 432        if (!ipc_ns) {
 433                error = -EACCES;
 434                goto out_unlock;
 435        }
 436        if (ipc_ns->mq_queues_count >= HARD_QUEUESMAX ||
 437            (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
 438             !capable(CAP_SYS_RESOURCE))) {
 439                error = -ENOSPC;
 440                goto out_unlock;
 441        }
 442        ipc_ns->mq_queues_count++;
 443        spin_unlock(&mq_lock);
 444
 445        inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
 446        if (IS_ERR(inode)) {
 447                error = PTR_ERR(inode);
 448                spin_lock(&mq_lock);
 449                ipc_ns->mq_queues_count--;
 450                goto out_unlock;
 451        }
 452
 453        put_ipc_ns(ipc_ns);
 454        dir->i_size += DIRENT_SIZE;
 455        dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 456
 457        d_instantiate(dentry, inode);
 458        dget(dentry);
 459        return 0;
 460out_unlock:
 461        spin_unlock(&mq_lock);
 462        if (ipc_ns)
 463                put_ipc_ns(ipc_ns);
 464        return error;
 465}
 466
 467static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
 468{
 469        struct inode *inode = dentry->d_inode;
 470
 471        dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 472        dir->i_size -= DIRENT_SIZE;
 473        drop_nlink(inode);
 474        dput(dentry);
 475        return 0;
 476}
 477
 478/*
 479*       This is routine for system read from queue file.
 480*       To avoid mess with doing here some sort of mq_receive we allow
 481*       to read only queue size & notification info (the only values
 482*       that are interesting from user point of view and aren't accessible
 483*       through std routines)
 484*/
 485static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
 486                                size_t count, loff_t *off)
 487{
 488        struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
 489        char buffer[FILENT_SIZE];
 490        ssize_t ret;
 491
 492        spin_lock(&info->lock);
 493        snprintf(buffer, sizeof(buffer),
 494                        "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
 495                        info->qsize,
 496                        info->notify_owner ? info->notify.sigev_notify : 0,
 497                        (info->notify_owner &&
 498                         info->notify.sigev_notify == SIGEV_SIGNAL) ?
 499                                info->notify.sigev_signo : 0,
 500                        pid_vnr(info->notify_owner));
 501        spin_unlock(&info->lock);
 502        buffer[sizeof(buffer)-1] = '\0';
 503
 504        ret = simple_read_from_buffer(u_data, count, off, buffer,
 505                                strlen(buffer));
 506        if (ret <= 0)
 507                return ret;
 508
 509        file_inode(filp)->i_atime = file_inode(filp)->i_ctime = CURRENT_TIME;
 510        return ret;
 511}
 512
 513static int mqueue_flush_file(struct file *filp, fl_owner_t id)
 514{
 515        struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
 516
 517        spin_lock(&info->lock);
 518        if (task_tgid(current) == info->notify_owner)
 519                remove_notification(info);
 520
 521        spin_unlock(&info->lock);
 522        return 0;
 523}
 524
 525static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
 526{
 527        struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
 528        int retval = 0;
 529
 530        poll_wait(filp, &info->wait_q, poll_tab);
 531
 532        spin_lock(&info->lock);
 533        if (info->attr.mq_curmsgs)
 534                retval = POLLIN | POLLRDNORM;
 535
 536        if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
 537                retval |= POLLOUT | POLLWRNORM;
 538        spin_unlock(&info->lock);
 539
 540        return retval;
 541}
 542
 543/* Adds current to info->e_wait_q[sr] before element with smaller prio */
 544static void wq_add(struct mqueue_inode_info *info, int sr,
 545                        struct ext_wait_queue *ewp)
 546{
 547        struct ext_wait_queue *walk;
 548
 549        ewp->task = current;
 550
 551        list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
 552                if (walk->task->static_prio <= current->static_prio) {
 553                        list_add_tail(&ewp->list, &walk->list);
 554                        return;
 555                }
 556        }
 557        list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
 558}
 559
 560/*
 561 * Puts current task to sleep. Caller must hold queue lock. After return
 562 * lock isn't held.
 563 * sr: SEND or RECV
 564 */
 565static int wq_sleep(struct mqueue_inode_info *info, int sr,
 566                    ktime_t *timeout, struct ext_wait_queue *ewp)
 567{
 568        int retval;
 569        signed long time;
 570
 571        wq_add(info, sr, ewp);
 572
 573        for (;;) {
 574                set_current_state(TASK_INTERRUPTIBLE);
 575
 576                spin_unlock(&info->lock);
 577                time = schedule_hrtimeout_range_clock(timeout, 0,
 578                        HRTIMER_MODE_ABS, CLOCK_REALTIME);
 579
 580                while (ewp->state == STATE_PENDING)
 581                        cpu_relax();
 582
 583                if (ewp->state == STATE_READY) {
 584                        retval = 0;
 585                        goto out;
 586                }
 587                spin_lock(&info->lock);
 588                if (ewp->state == STATE_READY) {
 589                        retval = 0;
 590                        goto out_unlock;
 591                }
 592                if (signal_pending(current)) {
 593                        retval = -ERESTARTSYS;
 594                        break;
 595                }
 596                if (time == 0) {
 597                        retval = -ETIMEDOUT;
 598                        break;
 599                }
 600        }
 601        list_del(&ewp->list);
 602out_unlock:
 603        spin_unlock(&info->lock);
 604out:
 605        return retval;
 606}
 607
 608/*
 609 * Returns waiting task that should be serviced first or NULL if none exists
 610 */
 611static struct ext_wait_queue *wq_get_first_waiter(
 612                struct mqueue_inode_info *info, int sr)
 613{
 614        struct list_head *ptr;
 615
 616        ptr = info->e_wait_q[sr].list.prev;
 617        if (ptr == &info->e_wait_q[sr].list)
 618                return NULL;
 619        return list_entry(ptr, struct ext_wait_queue, list);
 620}
 621
 622
 623static inline void set_cookie(struct sk_buff *skb, char code)
 624{
 625        ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
 626}
 627
 628/*
 629 * The next function is only to split too long sys_mq_timedsend
 630 */
 631static void __do_notify(struct mqueue_inode_info *info)
 632{
 633        /* notification
 634         * invoked when there is registered process and there isn't process
 635         * waiting synchronously for message AND state of queue changed from
 636         * empty to not empty. Here we are sure that no one is waiting
 637         * synchronously. */
 638        if (info->notify_owner &&
 639            info->attr.mq_curmsgs == 1) {
 640                struct siginfo sig_i;
 641                switch (info->notify.sigev_notify) {
 642                case SIGEV_NONE:
 643                        break;
 644                case SIGEV_SIGNAL:
 645                        /* sends signal */
 646
 647                        sig_i.si_signo = info->notify.sigev_signo;
 648                        sig_i.si_errno = 0;
 649                        sig_i.si_code = SI_MESGQ;
 650                        sig_i.si_value = info->notify.sigev_value;
 651                        /* map current pid/uid into info->owner's namespaces */
 652                        rcu_read_lock();
 653                        sig_i.si_pid = task_tgid_nr_ns(current,
 654                                                ns_of_pid(info->notify_owner));
 655                        sig_i.si_uid = from_kuid_munged(info->notify_user_ns, current_uid());
 656                        rcu_read_unlock();
 657
 658                        kill_pid_info(info->notify.sigev_signo,
 659                                      &sig_i, info->notify_owner);
 660                        break;
 661                case SIGEV_THREAD:
 662                        set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
 663                        netlink_sendskb(info->notify_sock, info->notify_cookie);
 664                        break;
 665                }
 666                /* after notification unregisters process */
 667                put_pid(info->notify_owner);
 668                put_user_ns(info->notify_user_ns);
 669                info->notify_owner = NULL;
 670                info->notify_user_ns = NULL;
 671        }
 672        wake_up(&info->wait_q);
 673}
 674
 675static int prepare_timeout(const struct timespec __user *u_abs_timeout,
 676                           ktime_t *expires, struct timespec *ts)
 677{
 678        if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec)))
 679                return -EFAULT;
 680        if (!timespec_valid(ts))
 681                return -EINVAL;
 682
 683        *expires = timespec_to_ktime(*ts);
 684        return 0;
 685}
 686
 687static void remove_notification(struct mqueue_inode_info *info)
 688{
 689        if (info->notify_owner != NULL &&
 690            info->notify.sigev_notify == SIGEV_THREAD) {
 691                set_cookie(info->notify_cookie, NOTIFY_REMOVED);
 692                netlink_sendskb(info->notify_sock, info->notify_cookie);
 693        }
 694        put_pid(info->notify_owner);
 695        put_user_ns(info->notify_user_ns);
 696        info->notify_owner = NULL;
 697        info->notify_user_ns = NULL;
 698}
 699
 700static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
 701{
 702        int mq_treesize;
 703        unsigned long total_size;
 704
 705        if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
 706                return -EINVAL;
 707        if (capable(CAP_SYS_RESOURCE)) {
 708                if (attr->mq_maxmsg > HARD_MSGMAX ||
 709                    attr->mq_msgsize > HARD_MSGSIZEMAX)
 710                        return -EINVAL;
 711        } else {
 712                if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
 713                                attr->mq_msgsize > ipc_ns->mq_msgsize_max)
 714                        return -EINVAL;
 715        }
 716        /* check for overflow */
 717        if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
 718                return -EOVERFLOW;
 719        mq_treesize = attr->mq_maxmsg * sizeof(struct msg_msg) +
 720                min_t(unsigned int, attr->mq_maxmsg, MQ_PRIO_MAX) *
 721                sizeof(struct posix_msg_tree_node);
 722        total_size = attr->mq_maxmsg * attr->mq_msgsize;
 723        if (total_size + mq_treesize < total_size)
 724                return -EOVERFLOW;
 725        return 0;
 726}
 727
 728/*
 729 * Invoked when creating a new queue via sys_mq_open
 730 */
 731static struct file *do_create(struct ipc_namespace *ipc_ns, struct inode *dir,
 732                        struct path *path, int oflag, umode_t mode,
 733                        struct mq_attr *attr)
 734{
 735        const struct cred *cred = current_cred();
 736        int ret;
 737
 738        if (attr) {
 739                ret = mq_attr_ok(ipc_ns, attr);
 740                if (ret)
 741                        return ERR_PTR(ret);
 742                /* store for use during create */
 743                path->dentry->d_fsdata = attr;
 744        } else {
 745                struct mq_attr def_attr;
 746
 747                def_attr.mq_maxmsg = min(ipc_ns->mq_msg_max,
 748                                         ipc_ns->mq_msg_default);
 749                def_attr.mq_msgsize = min(ipc_ns->mq_msgsize_max,
 750                                          ipc_ns->mq_msgsize_default);
 751                ret = mq_attr_ok(ipc_ns, &def_attr);
 752                if (ret)
 753                        return ERR_PTR(ret);
 754        }
 755
 756        mode &= ~current_umask();
 757        ret = vfs_create(dir, path->dentry, mode, true);
 758        path->dentry->d_fsdata = NULL;
 759        if (ret)
 760                return ERR_PTR(ret);
 761        return dentry_open(path, oflag, cred);
 762}
 763
 764/* Opens existing queue */
 765static struct file *do_open(struct path *path, int oflag)
 766{
 767        static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
 768                                                  MAY_READ | MAY_WRITE };
 769        int acc;
 770        if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY))
 771                return ERR_PTR(-EINVAL);
 772        acc = oflag2acc[oflag & O_ACCMODE];
 773        if (inode_permission(path->dentry->d_inode, acc))
 774                return ERR_PTR(-EACCES);
 775        return dentry_open(path, oflag, current_cred());
 776}
 777
 778SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
 779                struct mq_attr __user *, u_attr)
 780{
 781        struct path path;
 782        struct file *filp;
 783        struct filename *name;
 784        struct mq_attr attr;
 785        int fd, error;
 786        struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
 787        struct vfsmount *mnt = ipc_ns->mq_mnt;
 788        struct dentry *root = mnt->mnt_root;
 789        int ro;
 790
 791        if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
 792                return -EFAULT;
 793
 794        audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
 795
 796        if (IS_ERR(name = getname(u_name)))
 797                return PTR_ERR(name);
 798
 799        fd = get_unused_fd_flags(O_CLOEXEC);
 800        if (fd < 0)
 801                goto out_putname;
 802
 803        ro = mnt_want_write(mnt);       /* we'll drop it in any case */
 804        error = 0;
 805        mutex_lock(&root->d_inode->i_mutex);
 806        path.dentry = lookup_one_len(name->name, root, strlen(name->name));
 807        if (IS_ERR(path.dentry)) {
 808                error = PTR_ERR(path.dentry);
 809                goto out_putfd;
 810        }
 811        path.mnt = mntget(mnt);
 812
 813        if (oflag & O_CREAT) {
 814                if (path.dentry->d_inode) {     /* entry already exists */
 815                        audit_inode(name, path.dentry, 0);
 816                        if (oflag & O_EXCL) {
 817                                error = -EEXIST;
 818                                goto out;
 819                        }
 820                        filp = do_open(&path, oflag);
 821                } else {
 822                        if (ro) {
 823                                error = ro;
 824                                goto out;
 825                        }
 826                        filp = do_create(ipc_ns, root->d_inode,
 827                                                &path, oflag, mode,
 828                                                u_attr ? &attr : NULL);
 829                }
 830        } else {
 831                if (!path.dentry->d_inode) {
 832                        error = -ENOENT;
 833                        goto out;
 834                }
 835                audit_inode(name, path.dentry, 0);
 836                filp = do_open(&path, oflag);
 837        }
 838
 839        if (!IS_ERR(filp))
 840                fd_install(fd, filp);
 841        else
 842                error = PTR_ERR(filp);
 843out:
 844        path_put(&path);
 845out_putfd:
 846        if (error) {
 847                put_unused_fd(fd);
 848                fd = error;
 849        }
 850        mutex_unlock(&root->d_inode->i_mutex);
 851        if (!ro)
 852                mnt_drop_write(mnt);
 853out_putname:
 854        putname(name);
 855        return fd;
 856}
 857
 858SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
 859{
 860        int err;
 861        struct filename *name;
 862        struct dentry *dentry;
 863        struct inode *inode = NULL;
 864        struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
 865        struct vfsmount *mnt = ipc_ns->mq_mnt;
 866
 867        name = getname(u_name);
 868        if (IS_ERR(name))
 869                return PTR_ERR(name);
 870
 871        err = mnt_want_write(mnt);
 872        if (err)
 873                goto out_name;
 874        mutex_lock_nested(&mnt->mnt_root->d_inode->i_mutex, I_MUTEX_PARENT);
 875        dentry = lookup_one_len(name->name, mnt->mnt_root,
 876                                strlen(name->name));
 877        if (IS_ERR(dentry)) {
 878                err = PTR_ERR(dentry);
 879                goto out_unlock;
 880        }
 881
 882        inode = dentry->d_inode;
 883        if (!inode) {
 884                err = -ENOENT;
 885        } else {
 886                ihold(inode);
 887                err = vfs_unlink(dentry->d_parent->d_inode, dentry);
 888        }
 889        dput(dentry);
 890
 891out_unlock:
 892        mutex_unlock(&mnt->mnt_root->d_inode->i_mutex);
 893        if (inode)
 894                iput(inode);
 895        mnt_drop_write(mnt);
 896out_name:
 897        putname(name);
 898
 899        return err;
 900}
 901
 902/* Pipelined send and receive functions.
 903 *
 904 * If a receiver finds no waiting message, then it registers itself in the
 905 * list of waiting receivers. A sender checks that list before adding the new
 906 * message into the message array. If there is a waiting receiver, then it
 907 * bypasses the message array and directly hands the message over to the
 908 * receiver.
 909 * The receiver accepts the message and returns without grabbing the queue
 910 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
 911 * are necessary. The same algorithm is used for sysv semaphores, see
 912 * ipc/sem.c for more details.
 913 *
 914 * The same algorithm is used for senders.
 915 */
 916
 917/* pipelined_send() - send a message directly to the task waiting in
 918 * sys_mq_timedreceive() (without inserting message into a queue).
 919 */
 920static inline void pipelined_send(struct mqueue_inode_info *info,
 921                                  struct msg_msg *message,
 922                                  struct ext_wait_queue *receiver)
 923{
 924        receiver->msg = message;
 925        list_del(&receiver->list);
 926        receiver->state = STATE_PENDING;
 927        wake_up_process(receiver->task);
 928        smp_wmb();
 929        receiver->state = STATE_READY;
 930}
 931
 932/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
 933 * gets its message and put to the queue (we have one free place for sure). */
 934static inline void pipelined_receive(struct mqueue_inode_info *info)
 935{
 936        struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
 937
 938        if (!sender) {
 939                /* for poll */
 940                wake_up_interruptible(&info->wait_q);
 941                return;
 942        }
 943        if (msg_insert(sender->msg, info))
 944                return;
 945        list_del(&sender->list);
 946        sender->state = STATE_PENDING;
 947        wake_up_process(sender->task);
 948        smp_wmb();
 949        sender->state = STATE_READY;
 950}
 951
 952SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
 953                size_t, msg_len, unsigned int, msg_prio,
 954                const struct timespec __user *, u_abs_timeout)
 955{
 956        struct fd f;
 957        struct inode *inode;
 958        struct ext_wait_queue wait;
 959        struct ext_wait_queue *receiver;
 960        struct msg_msg *msg_ptr;
 961        struct mqueue_inode_info *info;
 962        ktime_t expires, *timeout = NULL;
 963        struct timespec ts;
 964        struct posix_msg_tree_node *new_leaf = NULL;
 965        int ret = 0;
 966
 967        if (u_abs_timeout) {
 968                int res = prepare_timeout(u_abs_timeout, &expires, &ts);
 969                if (res)
 970                        return res;
 971                timeout = &expires;
 972        }
 973
 974        if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
 975                return -EINVAL;
 976
 977        audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL);
 978
 979        f = fdget(mqdes);
 980        if (unlikely(!f.file)) {
 981                ret = -EBADF;
 982                goto out;
 983        }
 984
 985        inode = file_inode(f.file);
 986        if (unlikely(f.file->f_op != &mqueue_file_operations)) {
 987                ret = -EBADF;
 988                goto out_fput;
 989        }
 990        info = MQUEUE_I(inode);
 991        audit_inode(NULL, f.file->f_path.dentry, 0);
 992
 993        if (unlikely(!(f.file->f_mode & FMODE_WRITE))) {
 994                ret = -EBADF;
 995                goto out_fput;
 996        }
 997
 998        if (unlikely(msg_len > info->attr.mq_msgsize)) {
 999                ret = -EMSGSIZE;
1000                goto out_fput;
1001        }
1002
1003        /* First try to allocate memory, before doing anything with
1004         * existing queues. */
1005        msg_ptr = load_msg(u_msg_ptr, msg_len);
1006        if (IS_ERR(msg_ptr)) {
1007                ret = PTR_ERR(msg_ptr);
1008                goto out_fput;
1009        }
1010        msg_ptr->m_ts = msg_len;
1011        msg_ptr->m_type = msg_prio;
1012
1013        /*
1014         * msg_insert really wants us to have a valid, spare node struct so
1015         * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
1016         * fall back to that if necessary.
1017         */
1018        if (!info->node_cache)
1019                new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
1020
1021        spin_lock(&info->lock);
1022
1023        if (!info->node_cache && new_leaf) {
1024                /* Save our speculative allocation into the cache */
1025                INIT_LIST_HEAD(&new_leaf->msg_list);
1026                info->node_cache = new_leaf;
1027                info->qsize += sizeof(*new_leaf);
1028                new_leaf = NULL;
1029        } else {
1030                kfree(new_leaf);
1031        }
1032
1033        if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
1034                if (f.file->f_flags & O_NONBLOCK) {
1035                        ret = -EAGAIN;
1036                } else {
1037                        wait.task = current;
1038                        wait.msg = (void *) msg_ptr;
1039                        wait.state = STATE_NONE;
1040                        ret = wq_sleep(info, SEND, timeout, &wait);
1041                        /*
1042                         * wq_sleep must be called with info->lock held, and
1043                         * returns with the lock released
1044                         */
1045                        goto out_free;
1046                }
1047        } else {
1048                receiver = wq_get_first_waiter(info, RECV);
1049                if (receiver) {
1050                        pipelined_send(info, msg_ptr, receiver);
1051                } else {
1052                        /* adds message to the queue */
1053                        ret = msg_insert(msg_ptr, info);
1054                        if (ret)
1055                                goto out_unlock;
1056                        __do_notify(info);
1057                }
1058                inode->i_atime = inode->i_mtime = inode->i_ctime =
1059                                CURRENT_TIME;
1060        }
1061out_unlock:
1062        spin_unlock(&info->lock);
1063out_free:
1064        if (ret)
1065                free_msg(msg_ptr);
1066out_fput:
1067        fdput(f);
1068out:
1069        return ret;
1070}
1071
1072SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
1073                size_t, msg_len, unsigned int __user *, u_msg_prio,
1074                const struct timespec __user *, u_abs_timeout)
1075{
1076        ssize_t ret;
1077        struct msg_msg *msg_ptr;
1078        struct fd f;
1079        struct inode *inode;
1080        struct mqueue_inode_info *info;
1081        struct ext_wait_queue wait;
1082        ktime_t expires, *timeout = NULL;
1083        struct timespec ts;
1084        struct posix_msg_tree_node *new_leaf = NULL;
1085
1086        if (u_abs_timeout) {
1087                int res = prepare_timeout(u_abs_timeout, &expires, &ts);
1088                if (res)
1089                        return res;
1090                timeout = &expires;
1091        }
1092
1093        audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
1094
1095        f = fdget(mqdes);
1096        if (unlikely(!f.file)) {
1097                ret = -EBADF;
1098                goto out;
1099        }
1100
1101        inode = file_inode(f.file);
1102        if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1103                ret = -EBADF;
1104                goto out_fput;
1105        }
1106        info = MQUEUE_I(inode);
1107        audit_inode(NULL, f.file->f_path.dentry, 0);
1108
1109        if (unlikely(!(f.file->f_mode & FMODE_READ))) {
1110                ret = -EBADF;
1111                goto out_fput;
1112        }
1113
1114        /* checks if buffer is big enough */
1115        if (unlikely(msg_len < info->attr.mq_msgsize)) {
1116                ret = -EMSGSIZE;
1117                goto out_fput;
1118        }
1119
1120        /*
1121         * msg_insert really wants us to have a valid, spare node struct so
1122         * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
1123         * fall back to that if necessary.
1124         */
1125        if (!info->node_cache)
1126                new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
1127
1128        spin_lock(&info->lock);
1129
1130        if (!info->node_cache && new_leaf) {
1131                /* Save our speculative allocation into the cache */
1132                INIT_LIST_HEAD(&new_leaf->msg_list);
1133                info->node_cache = new_leaf;
1134                info->qsize += sizeof(*new_leaf);
1135        } else {
1136                kfree(new_leaf);
1137        }
1138
1139        if (info->attr.mq_curmsgs == 0) {
1140                if (f.file->f_flags & O_NONBLOCK) {
1141                        spin_unlock(&info->lock);
1142                        ret = -EAGAIN;
1143                } else {
1144                        wait.task = current;
1145                        wait.state = STATE_NONE;
1146                        ret = wq_sleep(info, RECV, timeout, &wait);
1147                        msg_ptr = wait.msg;
1148                }
1149        } else {
1150                msg_ptr = msg_get(info);
1151
1152                inode->i_atime = inode->i_mtime = inode->i_ctime =
1153                                CURRENT_TIME;
1154
1155                /* There is now free space in queue. */
1156                pipelined_receive(info);
1157                spin_unlock(&info->lock);
1158                ret = 0;
1159        }
1160        if (ret == 0) {
1161                ret = msg_ptr->m_ts;
1162
1163                if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1164                        store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1165                        ret = -EFAULT;
1166                }
1167                free_msg(msg_ptr);
1168        }
1169out_fput:
1170        fdput(f);
1171out:
1172        return ret;
1173}
1174
1175/*
1176 * Notes: the case when user wants us to deregister (with NULL as pointer)
1177 * and he isn't currently owner of notification, will be silently discarded.
1178 * It isn't explicitly defined in the POSIX.
1179 */
1180SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1181                const struct sigevent __user *, u_notification)
1182{
1183        int ret;
1184        struct fd f;
1185        struct sock *sock;
1186        struct inode *inode;
1187        struct sigevent notification;
1188        struct mqueue_inode_info *info;
1189        struct sk_buff *nc;
1190
1191        if (u_notification) {
1192                if (copy_from_user(&notification, u_notification,
1193                                        sizeof(struct sigevent)))
1194                        return -EFAULT;
1195        }
1196
1197        audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1198
1199        nc = NULL;
1200        sock = NULL;
1201        if (u_notification != NULL) {
1202                if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1203                             notification.sigev_notify != SIGEV_SIGNAL &&
1204                             notification.sigev_notify != SIGEV_THREAD))
1205                        return -EINVAL;
1206                if (notification.sigev_notify == SIGEV_SIGNAL &&
1207                        !valid_signal(notification.sigev_signo)) {
1208                        return -EINVAL;
1209                }
1210                if (notification.sigev_notify == SIGEV_THREAD) {
1211                        long timeo;
1212
1213                        /* create the notify skb */
1214                        nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1215                        if (!nc) {
1216                                ret = -ENOMEM;
1217                                goto out;
1218                        }
1219                        if (copy_from_user(nc->data,
1220                                        notification.sigev_value.sival_ptr,
1221                                        NOTIFY_COOKIE_LEN)) {
1222                                ret = -EFAULT;
1223                                goto out;
1224                        }
1225
1226                        /* TODO: add a header? */
1227                        skb_put(nc, NOTIFY_COOKIE_LEN);
1228                        /* and attach it to the socket */
1229retry:
1230                        f = fdget(notification.sigev_signo);
1231                        if (!f.file) {
1232                                ret = -EBADF;
1233                                goto out;
1234                        }
1235                        sock = netlink_getsockbyfilp(f.file);
1236                        fdput(f);
1237                        if (IS_ERR(sock)) {
1238                                ret = PTR_ERR(sock);
1239                                sock = NULL;
1240                                goto out;
1241                        }
1242
1243                        timeo = MAX_SCHEDULE_TIMEOUT;
1244                        ret = netlink_attachskb(sock, nc, &timeo, NULL);
1245                        if (ret == 1)
1246                                goto retry;
1247                        if (ret) {
1248                                sock = NULL;
1249                                nc = NULL;
1250                                goto out;
1251                        }
1252                }
1253        }
1254
1255        f = fdget(mqdes);
1256        if (!f.file) {
1257                ret = -EBADF;
1258                goto out;
1259        }
1260
1261        inode = file_inode(f.file);
1262        if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1263                ret = -EBADF;
1264                goto out_fput;
1265        }
1266        info = MQUEUE_I(inode);
1267
1268        ret = 0;
1269        spin_lock(&info->lock);
1270        if (u_notification == NULL) {
1271                if (info->notify_owner == task_tgid(current)) {
1272                        remove_notification(info);
1273                        inode->i_atime = inode->i_ctime = CURRENT_TIME;
1274                }
1275        } else if (info->notify_owner != NULL) {
1276                ret = -EBUSY;
1277        } else {
1278                switch (notification.sigev_notify) {
1279                case SIGEV_NONE:
1280                        info->notify.sigev_notify = SIGEV_NONE;
1281                        break;
1282                case SIGEV_THREAD:
1283                        info->notify_sock = sock;
1284                        info->notify_cookie = nc;
1285                        sock = NULL;
1286                        nc = NULL;
1287                        info->notify.sigev_notify = SIGEV_THREAD;
1288                        break;
1289                case SIGEV_SIGNAL:
1290                        info->notify.sigev_signo = notification.sigev_signo;
1291                        info->notify.sigev_value = notification.sigev_value;
1292                        info->notify.sigev_notify = SIGEV_SIGNAL;
1293                        break;
1294                }
1295
1296                info->notify_owner = get_pid(task_tgid(current));
1297                info->notify_user_ns = get_user_ns(current_user_ns());
1298                inode->i_atime = inode->i_ctime = CURRENT_TIME;
1299        }
1300        spin_unlock(&info->lock);
1301out_fput:
1302        fdput(f);
1303out:
1304        if (sock) {
1305                netlink_detachskb(sock, nc);
1306        } else if (nc) {
1307                dev_kfree_skb(nc);
1308        }
1309        return ret;
1310}
1311
1312SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1313                const struct mq_attr __user *, u_mqstat,
1314                struct mq_attr __user *, u_omqstat)
1315{
1316        int ret;
1317        struct mq_attr mqstat, omqstat;
1318        struct fd f;
1319        struct inode *inode;
1320        struct mqueue_inode_info *info;
1321
1322        if (u_mqstat != NULL) {
1323                if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1324                        return -EFAULT;
1325                if (mqstat.mq_flags & (~O_NONBLOCK))
1326                        return -EINVAL;
1327        }
1328
1329        f = fdget(mqdes);
1330        if (!f.file) {
1331                ret = -EBADF;
1332                goto out;
1333        }
1334
1335        inode = file_inode(f.file);
1336        if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1337                ret = -EBADF;
1338                goto out_fput;
1339        }
1340        info = MQUEUE_I(inode);
1341
1342        spin_lock(&info->lock);
1343
1344        omqstat = info->attr;
1345        omqstat.mq_flags = f.file->f_flags & O_NONBLOCK;
1346        if (u_mqstat) {
1347                audit_mq_getsetattr(mqdes, &mqstat);
1348                spin_lock(&f.file->f_lock);
1349                if (mqstat.mq_flags & O_NONBLOCK)
1350                        f.file->f_flags |= O_NONBLOCK;
1351                else
1352                        f.file->f_flags &= ~O_NONBLOCK;
1353                spin_unlock(&f.file->f_lock);
1354
1355                inode->i_atime = inode->i_ctime = CURRENT_TIME;
1356        }
1357
1358        spin_unlock(&info->lock);
1359
1360        ret = 0;
1361        if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1362                                                sizeof(struct mq_attr)))
1363                ret = -EFAULT;
1364
1365out_fput:
1366        fdput(f);
1367out:
1368        return ret;
1369}
1370
1371static const struct inode_operations mqueue_dir_inode_operations = {
1372        .lookup = simple_lookup,
1373        .create = mqueue_create,
1374        .unlink = mqueue_unlink,
1375};
1376
1377static const struct file_operations mqueue_file_operations = {
1378        .flush = mqueue_flush_file,
1379        .poll = mqueue_poll_file,
1380        .read = mqueue_read_file,
1381        .llseek = default_llseek,
1382};
1383
1384static const struct super_operations mqueue_super_ops = {
1385        .alloc_inode = mqueue_alloc_inode,
1386        .destroy_inode = mqueue_destroy_inode,
1387        .evict_inode = mqueue_evict_inode,
1388        .statfs = simple_statfs,
1389};
1390
1391static struct file_system_type mqueue_fs_type = {
1392        .name = "mqueue",
1393        .mount = mqueue_mount,
1394        .kill_sb = kill_litter_super,
1395        .fs_flags = FS_USERNS_MOUNT,
1396};
1397
1398int mq_init_ns(struct ipc_namespace *ns)
1399{
1400        ns->mq_queues_count  = 0;
1401        ns->mq_queues_max    = DFLT_QUEUESMAX;
1402        ns->mq_msg_max       = DFLT_MSGMAX;
1403        ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1404        ns->mq_msg_default   = DFLT_MSG;
1405        ns->mq_msgsize_default  = DFLT_MSGSIZE;
1406
1407        ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1408        if (IS_ERR(ns->mq_mnt)) {
1409                int err = PTR_ERR(ns->mq_mnt);
1410                ns->mq_mnt = NULL;
1411                return err;
1412        }
1413        return 0;
1414}
1415
1416void mq_clear_sbinfo(struct ipc_namespace *ns)
1417{
1418        ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1419}
1420
1421void mq_put_mnt(struct ipc_namespace *ns)
1422{
1423        kern_unmount(ns->mq_mnt);
1424}
1425
1426static int __init init_mqueue_fs(void)
1427{
1428        int error;
1429
1430        mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1431                                sizeof(struct mqueue_inode_info), 0,
1432                                SLAB_HWCACHE_ALIGN, init_once);
1433        if (mqueue_inode_cachep == NULL)
1434                return -ENOMEM;
1435
1436        /* ignore failures - they are not fatal */
1437        mq_sysctl_table = mq_register_sysctl_table();
1438
1439        error = register_filesystem(&mqueue_fs_type);
1440        if (error)
1441                goto out_sysctl;
1442
1443        spin_lock_init(&mq_lock);
1444
1445        error = mq_init_ns(&init_ipc_ns);
1446        if (error)
1447                goto out_filesystem;
1448
1449        return 0;
1450
1451out_filesystem:
1452        unregister_filesystem(&mqueue_fs_type);
1453out_sysctl:
1454        if (mq_sysctl_table)
1455                unregister_sysctl_table(mq_sysctl_table);
1456        kmem_cache_destroy(mqueue_inode_cachep);
1457        return error;
1458}
1459
1460__initcall(init_mqueue_fs);
1461
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.