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                rb_init_node(&leaf->rb_node);
 146                INIT_LIST_HEAD(&leaf->msg_list);
 147                info->qsize += sizeof(*leaf);
 148        }
 149        leaf->priority = msg->m_type;
 150        rb_link_node(&leaf->rb_node, parent, p);
 151        rb_insert_color(&leaf->rb_node, &info->msg_tree);
 152insert_msg:
 153        info->attr.mq_curmsgs++;
 154        info->qsize += msg->m_ts;
 155        list_add_tail(&msg->m_list, &leaf->msg_list);
 156        return 0;
 157}
 158
 159static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
 160{
 161        struct rb_node **p, *parent = NULL;
 162        struct posix_msg_tree_node *leaf;
 163        struct msg_msg *msg;
 164
 165try_again:
 166        p = &info->msg_tree.rb_node;
 167        while (*p) {
 168                parent = *p;
 169                /*
 170                 * During insert, low priorities go to the left and high to the
 171                 * right.  On receive, we want the highest priorities first, so
 172                 * walk all the way to the right.
 173                 */
 174                p = &(*p)->rb_right;
 175        }
 176        if (!parent) {
 177                if (info->attr.mq_curmsgs) {
 178                        pr_warn_once("Inconsistency in POSIX message queue, "
 179                                     "no tree element, but supposedly messages "
 180                                     "should exist!\n");
 181                        info->attr.mq_curmsgs = 0;
 182                }
 183                return NULL;
 184        }
 185        leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
 186        if (unlikely(list_empty(&leaf->msg_list))) {
 187                pr_warn_once("Inconsistency in POSIX message queue, "
 188                             "empty leaf node but we haven't implemented "
 189                             "lazy leaf delete!\n");
 190                rb_erase(&leaf->rb_node, &info->msg_tree);
 191                if (info->node_cache) {
 192                        info->qsize -= sizeof(*leaf);
 193                        kfree(leaf);
 194                } else {
 195                        info->node_cache = leaf;
 196                }
 197                goto try_again;
 198        } else {
 199                msg = list_first_entry(&leaf->msg_list,
 200                                       struct msg_msg, m_list);
 201                list_del(&msg->m_list);
 202                if (list_empty(&leaf->msg_list)) {
 203                        rb_erase(&leaf->rb_node, &info->msg_tree);
 204                        if (info->node_cache) {
 205                                info->qsize -= sizeof(*leaf);
 206                                kfree(leaf);
 207                        } else {
 208                                info->node_cache = leaf;
 209                        }
 210                }
 211        }
 212        info->attr.mq_curmsgs--;
 213        info->qsize -= msg->m_ts;
 214        return msg;
 215}
 216
 217static struct inode *mqueue_get_inode(struct super_block *sb,
 218                struct ipc_namespace *ipc_ns, umode_t mode,
 219                struct mq_attr *attr)
 220{
 221        struct user_struct *u = current_user();
 222        struct inode *inode;
 223        int ret = -ENOMEM;
 224
 225        inode = new_inode(sb);
 226        if (!inode)
 227                goto err;
 228
 229        inode->i_ino = get_next_ino();
 230        inode->i_mode = mode;
 231        inode->i_uid = current_fsuid();
 232        inode->i_gid = current_fsgid();
 233        inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME;
 234
 235        if (S_ISREG(mode)) {
 236                struct mqueue_inode_info *info;
 237                unsigned long mq_bytes, mq_treesize;
 238
 239                inode->i_fop = &mqueue_file_operations;
 240                inode->i_size = FILENT_SIZE;
 241                /* mqueue specific info */
 242                info = MQUEUE_I(inode);
 243                spin_lock_init(&info->lock);
 244                init_waitqueue_head(&info->wait_q);
 245                INIT_LIST_HEAD(&info->e_wait_q[0].list);
 246                INIT_LIST_HEAD(&info->e_wait_q[1].list);
 247                info->notify_owner = NULL;
 248                info->notify_user_ns = NULL;
 249                info->qsize = 0;
 250                info->user = NULL;      /* set when all is ok */
 251                info->msg_tree = RB_ROOT;
 252                info->node_cache = NULL;
 253                memset(&info->attr, 0, sizeof(info->attr));
 254                info->attr.mq_maxmsg = min(ipc_ns->mq_msg_max,
 255                                           ipc_ns->mq_msg_default);
 256                info->attr.mq_msgsize = min(ipc_ns->mq_msgsize_max,
 257                                            ipc_ns->mq_msgsize_default);
 258                if (attr) {
 259                        info->attr.mq_maxmsg = attr->mq_maxmsg;
 260                        info->attr.mq_msgsize = attr->mq_msgsize;
 261                }
 262                /*
 263                 * We used to allocate a static array of pointers and account
 264                 * the size of that array as well as one msg_msg struct per
 265                 * possible message into the queue size. That's no longer
 266                 * accurate as the queue is now an rbtree and will grow and
 267                 * shrink depending on usage patterns.  We can, however, still
 268                 * account one msg_msg struct per message, but the nodes are
 269                 * allocated depending on priority usage, and most programs
 270                 * only use one, or a handful, of priorities.  However, since
 271                 * this is pinned memory, we need to assume worst case, so
 272                 * that means the min(mq_maxmsg, max_priorities) * struct
 273                 * posix_msg_tree_node.
 274                 */
 275                mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
 276                        min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
 277                        sizeof(struct posix_msg_tree_node);
 278
 279                mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
 280                                          info->attr.mq_msgsize);
 281
 282                spin_lock(&mq_lock);
 283                if (u->mq_bytes + mq_bytes < u->mq_bytes ||
 284                    u->mq_bytes + mq_bytes > rlimit(RLIMIT_MSGQUEUE)) {
 285                        spin_unlock(&mq_lock);
 286                        /* mqueue_evict_inode() releases info->messages */
 287                        ret = -EMFILE;
 288                        goto out_inode;
 289                }
 290                u->mq_bytes += mq_bytes;
 291                spin_unlock(&mq_lock);
 292
 293                /* all is ok */
 294                info->user = get_uid(u);
 295        } else if (S_ISDIR(mode)) {
 296                inc_nlink(inode);
 297                /* Some things misbehave if size == 0 on a directory */
 298                inode->i_size = 2 * DIRENT_SIZE;
 299                inode->i_op = &mqueue_dir_inode_operations;
 300                inode->i_fop = &simple_dir_operations;
 301        }
 302
 303        return inode;
 304out_inode:
 305        iput(inode);
 306err:
 307        return ERR_PTR(ret);
 308}
 309
 310static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
 311{
 312        struct inode *inode;
 313        struct ipc_namespace *ns = data;
 314
 315        sb->s_blocksize = PAGE_CACHE_SIZE;
 316        sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 317        sb->s_magic = MQUEUE_MAGIC;
 318        sb->s_op = &mqueue_super_ops;
 319
 320        inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
 321        if (IS_ERR(inode))
 322                return PTR_ERR(inode);
 323
 324        sb->s_root = d_make_root(inode);
 325        if (!sb->s_root)
 326                return -ENOMEM;
 327        return 0;
 328}
 329
 330static struct dentry *mqueue_mount(struct file_system_type *fs_type,
 331                         int flags, const char *dev_name,
 332                         void *data)
 333{
 334        if (!(flags & MS_KERNMOUNT))
 335                data = current->nsproxy->ipc_ns;
 336        return mount_ns(fs_type, flags, data, mqueue_fill_super);
 337}
 338
 339static void init_once(void *foo)
 340{
 341        struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
 342
 343        inode_init_once(&p->vfs_inode);
 344}
 345
 346static struct inode *mqueue_alloc_inode(struct super_block *sb)
 347{
 348        struct mqueue_inode_info *ei;
 349
 350        ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
 351        if (!ei)
 352                return NULL;
 353        return &ei->vfs_inode;
 354}
 355
 356static void mqueue_i_callback(struct rcu_head *head)
 357{
 358        struct inode *inode = container_of(head, struct inode, i_rcu);
 359        kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
 360}
 361
 362static void mqueue_destroy_inode(struct inode *inode)
 363{
 364        call_rcu(&inode->i_rcu, mqueue_i_callback);
 365}
 366
 367static void mqueue_evict_inode(struct inode *inode)
 368{
 369        struct mqueue_inode_info *info;
 370        struct user_struct *user;
 371        unsigned long mq_bytes, mq_treesize;
 372        struct ipc_namespace *ipc_ns;
 373        struct msg_msg *msg;
 374
 375        clear_inode(inode);
 376
 377        if (S_ISDIR(inode->i_mode))
 378                return;
 379
 380        ipc_ns = get_ns_from_inode(inode);
 381        info = MQUEUE_I(inode);
 382        spin_lock(&info->lock);
 383        while ((msg = msg_get(info)) != NULL)
 384                free_msg(msg);
 385        kfree(info->node_cache);
 386        spin_unlock(&info->lock);
 387
 388        /* Total amount of bytes accounted for the mqueue */
 389        mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
 390                min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
 391                sizeof(struct posix_msg_tree_node);
 392
 393        mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
 394                                  info->attr.mq_msgsize);
 395
 396        user = info->user;
 397        if (user) {
 398                spin_lock(&mq_lock);
 399                user->mq_bytes -= mq_bytes;
 400                /*
 401                 * get_ns_from_inode() ensures that the
 402                 * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
 403                 * to which we now hold a reference, or it is NULL.
 404                 * We can't put it here under mq_lock, though.
 405                 */
 406                if (ipc_ns)
 407                        ipc_ns->mq_queues_count--;
 408                spin_unlock(&mq_lock);
 409                free_uid(user);
 410        }
 411        if (ipc_ns)
 412                put_ipc_ns(ipc_ns);
 413}
 414
 415static int mqueue_create(struct inode *dir, struct dentry *dentry,
 416                                umode_t mode, struct nameidata *nd)
 417{
 418        struct inode *inode;
 419        struct mq_attr *attr = dentry->d_fsdata;
 420        int error;
 421        struct ipc_namespace *ipc_ns;
 422
 423        spin_lock(&mq_lock);
 424        ipc_ns = __get_ns_from_inode(dir);
 425        if (!ipc_ns) {
 426                error = -EACCES;
 427                goto out_unlock;
 428        }
 429        if (ipc_ns->mq_queues_count >= HARD_QUEUESMAX ||
 430            (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
 431             !capable(CAP_SYS_RESOURCE))) {
 432                error = -ENOSPC;
 433                goto out_unlock;
 434        }
 435        ipc_ns->mq_queues_count++;
 436        spin_unlock(&mq_lock);
 437
 438        inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
 439        if (IS_ERR(inode)) {
 440                error = PTR_ERR(inode);
 441                spin_lock(&mq_lock);
 442                ipc_ns->mq_queues_count--;
 443                goto out_unlock;
 444        }
 445
 446        put_ipc_ns(ipc_ns);
 447        dir->i_size += DIRENT_SIZE;
 448        dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 449
 450        d_instantiate(dentry, inode);
 451        dget(dentry);
 452        return 0;
 453out_unlock:
 454        spin_unlock(&mq_lock);
 455        if (ipc_ns)
 456                put_ipc_ns(ipc_ns);
 457        return error;
 458}
 459
 460static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
 461{
 462        struct inode *inode = dentry->d_inode;
 463
 464        dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
 465        dir->i_size -= DIRENT_SIZE;
 466        drop_nlink(inode);
 467        dput(dentry);
 468        return 0;
 469}
 470
 471/*
 472*       This is routine for system read from queue file.
 473*       To avoid mess with doing here some sort of mq_receive we allow
 474*       to read only queue size & notification info (the only values
 475*       that are interesting from user point of view and aren't accessible
 476*       through std routines)
 477*/
 478static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
 479                                size_t count, loff_t *off)
 480{
 481        struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 482        char buffer[FILENT_SIZE];
 483        ssize_t ret;
 484
 485        spin_lock(&info->lock);
 486        snprintf(buffer, sizeof(buffer),
 487                        "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
 488                        info->qsize,
 489                        info->notify_owner ? info->notify.sigev_notify : 0,
 490                        (info->notify_owner &&
 491                         info->notify.sigev_notify == SIGEV_SIGNAL) ?
 492                                info->notify.sigev_signo : 0,
 493                        pid_vnr(info->notify_owner));
 494        spin_unlock(&info->lock);
 495        buffer[sizeof(buffer)-1] = '\0';
 496
 497        ret = simple_read_from_buffer(u_data, count, off, buffer,
 498                                strlen(buffer));
 499        if (ret <= 0)
 500                return ret;
 501
 502        filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
 503        return ret;
 504}
 505
 506static int mqueue_flush_file(struct file *filp, fl_owner_t id)
 507{
 508        struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 509
 510        spin_lock(&info->lock);
 511        if (task_tgid(current) == info->notify_owner)
 512                remove_notification(info);
 513
 514        spin_unlock(&info->lock);
 515        return 0;
 516}
 517
 518static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
 519{
 520        struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 521        int retval = 0;
 522
 523        poll_wait(filp, &info->wait_q, poll_tab);
 524
 525        spin_lock(&info->lock);
 526        if (info->attr.mq_curmsgs)
 527                retval = POLLIN | POLLRDNORM;
 528
 529        if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
 530                retval |= POLLOUT | POLLWRNORM;
 531        spin_unlock(&info->lock);
 532
 533        return retval;
 534}
 535
 536/* Adds current to info->e_wait_q[sr] before element with smaller prio */
 537static void wq_add(struct mqueue_inode_info *info, int sr,
 538                        struct ext_wait_queue *ewp)
 539{
 540        struct ext_wait_queue *walk;
 541
 542        ewp->task = current;
 543
 544        list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
 545                if (walk->task->static_prio <= current->static_prio) {
 546                        list_add_tail(&ewp->list, &walk->list);
 547                        return;
 548                }
 549        }
 550        list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
 551}
 552
 553/*
 554 * Puts current task to sleep. Caller must hold queue lock. After return
 555 * lock isn't held.
 556 * sr: SEND or RECV
 557 */
 558static int wq_sleep(struct mqueue_inode_info *info, int sr,
 559                    ktime_t *timeout, struct ext_wait_queue *ewp)
 560{
 561        int retval;
 562        signed long time;
 563
 564        wq_add(info, sr, ewp);
 565
 566        for (;;) {
 567                set_current_state(TASK_INTERRUPTIBLE);
 568
 569                spin_unlock(&info->lock);
 570                time = schedule_hrtimeout_range_clock(timeout, 0,
 571                        HRTIMER_MODE_ABS, CLOCK_REALTIME);
 572
 573                while (ewp->state == STATE_PENDING)
 574                        cpu_relax();
 575
 576                if (ewp->state == STATE_READY) {
 577                        retval = 0;
 578                        goto out;
 579                }
 580                spin_lock(&info->lock);
 581                if (ewp->state == STATE_READY) {
 582                        retval = 0;
 583                        goto out_unlock;
 584                }
 585                if (signal_pending(current)) {
 586                        retval = -ERESTARTSYS;
 587                        break;
 588                }
 589                if (time == 0) {
 590                        retval = -ETIMEDOUT;
 591                        break;
 592                }
 593        }
 594        list_del(&ewp->list);
 595out_unlock:
 596        spin_unlock(&info->lock);
 597out:
 598        return retval;
 599}
 600
 601/*
 602 * Returns waiting task that should be serviced first or NULL if none exists
 603 */
 604static struct ext_wait_queue *wq_get_first_waiter(
 605                struct mqueue_inode_info *info, int sr)
 606{
 607        struct list_head *ptr;
 608
 609        ptr = info->e_wait_q[sr].list.prev;
 610        if (ptr == &info->e_wait_q[sr].list)
 611                return NULL;
 612        return list_entry(ptr, struct ext_wait_queue, list);
 613}
 614
 615
 616static inline void set_cookie(struct sk_buff *skb, char code)
 617{
 618        ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
 619}
 620
 621/*
 622 * The next function is only to split too long sys_mq_timedsend
 623 */
 624static void __do_notify(struct mqueue_inode_info *info)
 625{
 626        /* notification
 627         * invoked when there is registered process and there isn't process
 628         * waiting synchronously for message AND state of queue changed from
 629         * empty to not empty. Here we are sure that no one is waiting
 630         * synchronously. */
 631        if (info->notify_owner &&
 632            info->attr.mq_curmsgs == 1) {
 633                struct siginfo sig_i;
 634                switch (info->notify.sigev_notify) {
 635                case SIGEV_NONE:
 636                        break;
 637                case SIGEV_SIGNAL:
 638                        /* sends signal */
 639
 640                        sig_i.si_signo = info->notify.sigev_signo;
 641                        sig_i.si_errno = 0;
 642                        sig_i.si_code = SI_MESGQ;
 643                        sig_i.si_value = info->notify.sigev_value;
 644                        /* map current pid/uid into info->owner's namespaces */
 645                        rcu_read_lock();
 646                        sig_i.si_pid = task_tgid_nr_ns(current,
 647                                                ns_of_pid(info->notify_owner));
 648                        sig_i.si_uid = from_kuid_munged(info->notify_user_ns, current_uid());
 649                        rcu_read_unlock();
 650
 651                        kill_pid_info(info->notify.sigev_signo,
 652                                      &sig_i, info->notify_owner);
 653                        break;
 654                case SIGEV_THREAD:
 655                        set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
 656                        netlink_sendskb(info->notify_sock, info->notify_cookie);
 657                        break;
 658                }
 659                /* after notification unregisters process */
 660                put_pid(info->notify_owner);
 661                put_user_ns(info->notify_user_ns);
 662                info->notify_owner = NULL;
 663                info->notify_user_ns = NULL;
 664        }
 665        wake_up(&info->wait_q);
 666}
 667
 668static int prepare_timeout(const struct timespec __user *u_abs_timeout,
 669                           ktime_t *expires, struct timespec *ts)
 670{
 671        if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec)))
 672                return -EFAULT;
 673        if (!timespec_valid(ts))
 674                return -EINVAL;
 675
 676        *expires = timespec_to_ktime(*ts);
 677        return 0;
 678}
 679
 680static void remove_notification(struct mqueue_inode_info *info)
 681{
 682        if (info->notify_owner != NULL &&
 683            info->notify.sigev_notify == SIGEV_THREAD) {
 684                set_cookie(info->notify_cookie, NOTIFY_REMOVED);
 685                netlink_sendskb(info->notify_sock, info->notify_cookie);
 686        }
 687        put_pid(info->notify_owner);
 688        put_user_ns(info->notify_user_ns);
 689        info->notify_owner = NULL;
 690        info->notify_user_ns = NULL;
 691}
 692
 693static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
 694{
 695        int mq_treesize;
 696        unsigned long total_size;
 697
 698        if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
 699                return -EINVAL;
 700        if (capable(CAP_SYS_RESOURCE)) {
 701                if (attr->mq_maxmsg > HARD_MSGMAX ||
 702                    attr->mq_msgsize > HARD_MSGSIZEMAX)
 703                        return -EINVAL;
 704        } else {
 705                if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
 706                                attr->mq_msgsize > ipc_ns->mq_msgsize_max)
 707                        return -EINVAL;
 708        }
 709        /* check for overflow */
 710        if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
 711                return -EOVERFLOW;
 712        mq_treesize = attr->mq_maxmsg * sizeof(struct msg_msg) +
 713                min_t(unsigned int, attr->mq_maxmsg, MQ_PRIO_MAX) *
 714                sizeof(struct posix_msg_tree_node);
 715        total_size = attr->mq_maxmsg * attr->mq_msgsize;
 716        if (total_size + mq_treesize < total_size)
 717                return -EOVERFLOW;
 718        return 0;
 719}
 720
 721/*
 722 * Invoked when creating a new queue via sys_mq_open
 723 */
 724static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir,
 725                        struct dentry *dentry, int oflag, umode_t mode,
 726                        struct mq_attr *attr)
 727{
 728        const struct cred *cred = current_cred();
 729        struct file *result;
 730        int ret;
 731
 732        if (attr) {
 733                ret = mq_attr_ok(ipc_ns, attr);
 734                if (ret)
 735                        goto out;
 736                /* store for use during create */
 737                dentry->d_fsdata = attr;
 738        } else {
 739                struct mq_attr def_attr;
 740
 741                def_attr.mq_maxmsg = min(ipc_ns->mq_msg_max,
 742                                         ipc_ns->mq_msg_default);
 743                def_attr.mq_msgsize = min(ipc_ns->mq_msgsize_max,
 744                                          ipc_ns->mq_msgsize_default);
 745                ret = mq_attr_ok(ipc_ns, &def_attr);
 746                if (ret)
 747                        goto out;
 748        }
 749
 750        mode &= ~current_umask();
 751        ret = mnt_want_write(ipc_ns->mq_mnt);
 752        if (ret)
 753                goto out;
 754        ret = vfs_create(dir->d_inode, dentry, mode, NULL);
 755        dentry->d_fsdata = NULL;
 756        if (ret)
 757                goto out_drop_write;
 758
 759        result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
 760        /*
 761         * dentry_open() took a persistent mnt_want_write(),
 762         * so we can now drop this one.
 763         */
 764        mnt_drop_write(ipc_ns->mq_mnt);
 765        return result;
 766
 767out_drop_write:
 768        mnt_drop_write(ipc_ns->mq_mnt);
 769out:
 770        dput(dentry);
 771        mntput(ipc_ns->mq_mnt);
 772        return ERR_PTR(ret);
 773}
 774
 775/* Opens existing queue */
 776static struct file *do_open(struct ipc_namespace *ipc_ns,
 777                                struct dentry *dentry, int oflag)
 778{
 779        int ret;
 780        const struct cred *cred = current_cred();
 781
 782        static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
 783                                                  MAY_READ | MAY_WRITE };
 784
 785        if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
 786                ret = -EINVAL;
 787                goto err;
 788        }
 789
 790        if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
 791                ret = -EACCES;
 792                goto err;
 793        }
 794
 795        return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
 796
 797err:
 798        dput(dentry);
 799        mntput(ipc_ns->mq_mnt);
 800        return ERR_PTR(ret);
 801}
 802
 803SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
 804                struct mq_attr __user *, u_attr)
 805{
 806        struct dentry *dentry;
 807        struct file *filp;
 808        char *name;
 809        struct mq_attr attr;
 810        int fd, error;
 811        struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
 812
 813        if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
 814                return -EFAULT;
 815
 816        audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
 817
 818        if (IS_ERR(name = getname(u_name)))
 819                return PTR_ERR(name);
 820
 821        fd = get_unused_fd_flags(O_CLOEXEC);
 822        if (fd < 0)
 823                goto out_putname;
 824
 825        mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 826        dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
 827        if (IS_ERR(dentry)) {
 828                error = PTR_ERR(dentry);
 829                goto out_putfd;
 830        }
 831        mntget(ipc_ns->mq_mnt);
 832
 833        if (oflag & O_CREAT) {
 834                if (dentry->d_inode) {  /* entry already exists */
 835                        audit_inode(name, dentry);
 836                        if (oflag & O_EXCL) {
 837                                error = -EEXIST;
 838                                goto out;
 839                        }
 840                        filp = do_open(ipc_ns, dentry, oflag);
 841                } else {
 842                        filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root,
 843                                                dentry, oflag, mode,
 844                                                u_attr ? &attr : NULL);
 845                }
 846        } else {
 847                if (!dentry->d_inode) {
 848                        error = -ENOENT;
 849                        goto out;
 850                }
 851                audit_inode(name, dentry);
 852                filp = do_open(ipc_ns, dentry, oflag);
 853        }
 854
 855        if (IS_ERR(filp)) {
 856                error = PTR_ERR(filp);
 857                goto out_putfd;
 858        }
 859
 860        fd_install(fd, filp);
 861        goto out_upsem;
 862
 863out:
 864        dput(dentry);
 865        mntput(ipc_ns->mq_mnt);
 866out_putfd:
 867        put_unused_fd(fd);
 868        fd = error;
 869out_upsem:
 870        mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 871out_putname:
 872        putname(name);
 873        return fd;
 874}
 875
 876SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
 877{
 878        int err;
 879        char *name;
 880        struct dentry *dentry;
 881        struct inode *inode = NULL;
 882        struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
 883
 884        name = getname(u_name);
 885        if (IS_ERR(name))
 886                return PTR_ERR(name);
 887
 888        mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
 889                        I_MUTEX_PARENT);
 890        dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
 891        if (IS_ERR(dentry)) {
 892                err = PTR_ERR(dentry);
 893                goto out_unlock;
 894        }
 895
 896        if (!dentry->d_inode) {
 897                err = -ENOENT;
 898                goto out_err;
 899        }
 900
 901        inode = dentry->d_inode;
 902        if (inode)
 903                ihold(inode);
 904        err = mnt_want_write(ipc_ns->mq_mnt);
 905        if (err)
 906                goto out_err;
 907        err = vfs_unlink(dentry->d_parent->d_inode, dentry);
 908        mnt_drop_write(ipc_ns->mq_mnt);
 909out_err:
 910        dput(dentry);
 911
 912out_unlock:
 913        mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
 914        putname(name);
 915        if (inode)
 916                iput(inode);
 917
 918        return err;
 919}
 920
 921/* Pipelined send and receive functions.
 922 *
 923 * If a receiver finds no waiting message, then it registers itself in the
 924 * list of waiting receivers. A sender checks that list before adding the new
 925 * message into the message array. If there is a waiting receiver, then it
 926 * bypasses the message array and directly hands the message over to the
 927 * receiver.
 928 * The receiver accepts the message and returns without grabbing the queue
 929 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
 930 * are necessary. The same algorithm is used for sysv semaphores, see
 931 * ipc/sem.c for more details.
 932 *
 933 * The same algorithm is used for senders.
 934 */
 935
 936/* pipelined_send() - send a message directly to the task waiting in
 937 * sys_mq_timedreceive() (without inserting message into a queue).
 938 */
 939static inline void pipelined_send(struct mqueue_inode_info *info,
 940                                  struct msg_msg *message,
 941                                  struct ext_wait_queue *receiver)
 942{
 943        receiver->msg = message;
 944        list_del(&receiver->list);
 945        receiver->state = STATE_PENDING;
 946        wake_up_process(receiver->task);
 947        smp_wmb();
 948        receiver->state = STATE_READY;
 949}
 950
 951/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
 952 * gets its message and put to the queue (we have one free place for sure). */
 953static inline void pipelined_receive(struct mqueue_inode_info *info)
 954{
 955        struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
 956
 957        if (!sender) {
 958                /* for poll */
 959                wake_up_interruptible(&info->wait_q);
 960                return;
 961        }
 962        if (msg_insert(sender->msg, info))
 963                return;
 964        list_del(&sender->list);
 965        sender->state = STATE_PENDING;
 966        wake_up_process(sender->task);
 967        smp_wmb();
 968        sender->state = STATE_READY;
 969}
 970
 971SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
 972                size_t, msg_len, unsigned int, msg_prio,
 973                const struct timespec __user *, u_abs_timeout)
 974{
 975        struct file *filp;
 976        struct inode *inode;
 977        struct ext_wait_queue wait;
 978        struct ext_wait_queue *receiver;
 979        struct msg_msg *msg_ptr;
 980        struct mqueue_inode_info *info;
 981        ktime_t expires, *timeout = NULL;
 982        struct timespec ts;
 983        struct posix_msg_tree_node *new_leaf = NULL;
 984        int ret = 0;
 985
 986        if (u_abs_timeout) {
 987                int res = prepare_timeout(u_abs_timeout, &expires, &ts);
 988                if (res)
 989                        return res;
 990                timeout = &expires;
 991        }
 992
 993        if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
 994                return -EINVAL;
 995
 996        audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL);
 997
 998        filp = fget(mqdes);
 999        if (unlikely(!filp)) {
1000                ret = -EBADF;
1001                goto out;
1002        }
1003
1004        inode = filp->f_path.dentry->d_inode;
1005        if (unlikely(filp->f_op != &mqueue_file_operations)) {
1006                ret = -EBADF;
1007                goto out_fput;
1008        }
1009        info = MQUEUE_I(inode);
1010        audit_inode(NULL, filp->f_path.dentry);
1011
1012        if (unlikely(!(filp->f_mode & FMODE_WRITE))) {
1013                ret = -EBADF;
1014                goto out_fput;
1015        }
1016
1017        if (unlikely(msg_len > info->attr.mq_msgsize)) {
1018                ret = -EMSGSIZE;
1019                goto out_fput;
1020        }
1021
1022        /* First try to allocate memory, before doing anything with
1023         * existing queues. */
1024        msg_ptr = load_msg(u_msg_ptr, msg_len);
1025        if (IS_ERR(msg_ptr)) {
1026                ret = PTR_ERR(msg_ptr);
1027                goto out_fput;
1028        }
1029        msg_ptr->m_ts = msg_len;
1030        msg_ptr->m_type = msg_prio;
1031
1032        /*
1033         * msg_insert really wants us to have a valid, spare node struct so
1034         * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
1035         * fall back to that if necessary.
1036         */
1037        if (!info->node_cache)
1038                new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
1039
1040        spin_lock(&info->lock);
1041
1042        if (!info->node_cache && new_leaf) {
1043                /* Save our speculative allocation into the cache */
1044                rb_init_node(&new_leaf->rb_node);
1045                INIT_LIST_HEAD(&new_leaf->msg_list);
1046                info->node_cache = new_leaf;
1047                info->qsize += sizeof(*new_leaf);
1048                new_leaf = NULL;
1049        } else {
1050                kfree(new_leaf);
1051        }
1052
1053        if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
1054                if (filp->f_flags & O_NONBLOCK) {
1055                        ret = -EAGAIN;
1056                } else {
1057                        wait.task = current;
1058                        wait.msg = (void *) msg_ptr;
1059                        wait.state = STATE_NONE;
1060                        ret = wq_sleep(info, SEND, timeout, &wait);
1061                        /*
1062                         * wq_sleep must be called with info->lock held, and
1063                         * returns with the lock released
1064                         */
1065                        goto out_free;
1066                }
1067        } else {
1068                receiver = wq_get_first_waiter(info, RECV);
1069                if (receiver) {
1070                        pipelined_send(info, msg_ptr, receiver);
1071                } else {
1072                        /* adds message to the queue */
1073                        ret = msg_insert(msg_ptr, info);
1074                        if (ret)
1075                                goto out_unlock;
1076                        __do_notify(info);
1077                }
1078                inode->i_atime = inode->i_mtime = inode->i_ctime =
1079                                CURRENT_TIME;
1080        }
1081out_unlock:
1082        spin_unlock(&info->lock);
1083out_free:
1084        if (ret)
1085                free_msg(msg_ptr);
1086out_fput:
1087        fput(filp);
1088out:
1089        return ret;
1090}
1091
1092SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
1093                size_t, msg_len, unsigned int __user *, u_msg_prio,
1094                const struct timespec __user *, u_abs_timeout)
1095{
1096        ssize_t ret;
1097        struct msg_msg *msg_ptr;
1098        struct file *filp;
1099        struct inode *inode;
1100        struct mqueue_inode_info *info;
1101        struct ext_wait_queue wait;
1102        ktime_t expires, *timeout = NULL;
1103        struct timespec ts;
1104        struct posix_msg_tree_node *new_leaf = NULL;
1105
1106        if (u_abs_timeout) {
1107                int res = prepare_timeout(u_abs_timeout, &expires, &ts);
1108                if (res)
1109                        return res;
1110                timeout = &expires;
1111        }
1112
1113        audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
1114
1115        filp = fget(mqdes);
1116        if (unlikely(!filp)) {
1117                ret = -EBADF;
1118                goto out;
1119        }
1120
1121        inode = filp->f_path.dentry->d_inode;
1122        if (unlikely(filp->f_op != &mqueue_file_operations)) {
1123                ret = -EBADF;
1124                goto out_fput;
1125        }
1126        info = MQUEUE_I(inode);
1127        audit_inode(NULL, filp->f_path.dentry);
1128
1129        if (unlikely(!(filp->f_mode & FMODE_READ))) {
1130                ret = -EBADF;
1131                goto out_fput;
1132        }
1133
1134        /* checks if buffer is big enough */
1135        if (unlikely(msg_len < info->attr.mq_msgsize)) {
1136                ret = -EMSGSIZE;
1137                goto out_fput;
1138        }
1139
1140        /*
1141         * msg_insert really wants us to have a valid, spare node struct so
1142         * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
1143         * fall back to that if necessary.
1144         */
1145        if (!info->node_cache)
1146                new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
1147
1148        spin_lock(&info->lock);
1149
1150        if (!info->node_cache && new_leaf) {
1151                /* Save our speculative allocation into the cache */
1152                rb_init_node(&new_leaf->rb_node);
1153                INIT_LIST_HEAD(&new_leaf->msg_list);
1154                info->node_cache = new_leaf;
1155                info->qsize += sizeof(*new_leaf);
1156        } else {
1157                kfree(new_leaf);
1158        }
1159
1160        if (info->attr.mq_curmsgs == 0) {
1161                if (filp->f_flags & O_NONBLOCK) {
1162                        spin_unlock(&info->lock);
1163                        ret = -EAGAIN;
1164                } else {
1165                        wait.task = current;
1166                        wait.state = STATE_NONE;
1167                        ret = wq_sleep(info, RECV, timeout, &wait);
1168                        msg_ptr = wait.msg;
1169                }
1170        } else {
1171                msg_ptr = msg_get(info);
1172
1173                inode->i_atime = inode->i_mtime = inode->i_ctime =
1174                                CURRENT_TIME;
1175
1176                /* There is now free space in queue. */
1177                pipelined_receive(info);
1178                spin_unlock(&info->lock);
1179                ret = 0;
1180        }
1181        if (ret == 0) {
1182                ret = msg_ptr->m_ts;
1183
1184                if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1185                        store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1186                        ret = -EFAULT;
1187                }
1188                free_msg(msg_ptr);
1189        }
1190out_fput:
1191        fput(filp);
1192out:
1193        return ret;
1194}
1195
1196/*
1197 * Notes: the case when user wants us to deregister (with NULL as pointer)
1198 * and he isn't currently owner of notification, will be silently discarded.
1199 * It isn't explicitly defined in the POSIX.
1200 */
1201SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1202                const struct sigevent __user *, u_notification)
1203{
1204        int ret;
1205        struct file *filp;
1206        struct sock *sock;
1207        struct inode *inode;
1208        struct sigevent notification;
1209        struct mqueue_inode_info *info;
1210        struct sk_buff *nc;
1211
1212        if (u_notification) {
1213                if (copy_from_user(&notification, u_notification,
1214                                        sizeof(struct sigevent)))
1215                        return -EFAULT;
1216        }
1217
1218        audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1219
1220        nc = NULL;
1221        sock = NULL;
1222        if (u_notification != NULL) {
1223                if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1224                             notification.sigev_notify != SIGEV_SIGNAL &&
1225                             notification.sigev_notify != SIGEV_THREAD))
1226                        return -EINVAL;
1227                if (notification.sigev_notify == SIGEV_SIGNAL &&
1228                        !valid_signal(notification.sigev_signo)) {
1229                        return -EINVAL;
1230                }
1231                if (notification.sigev_notify == SIGEV_THREAD) {
1232                        long timeo;
1233
1234                        /* create the notify skb */
1235                        nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1236                        if (!nc) {
1237                                ret = -ENOMEM;
1238                                goto out;
1239                        }
1240                        if (copy_from_user(nc->data,
1241                                        notification.sigev_value.sival_ptr,
1242                                        NOTIFY_COOKIE_LEN)) {
1243                                ret = -EFAULT;
1244                                goto out;
1245                        }
1246
1247                        /* TODO: add a header? */
1248                        skb_put(nc, NOTIFY_COOKIE_LEN);
1249                        /* and attach it to the socket */
1250retry:
1251                        filp = fget(notification.sigev_signo);
1252                        if (!filp) {
1253                                ret = -EBADF;
1254                                goto out;
1255                        }
1256                        sock = netlink_getsockbyfilp(filp);
1257                        fput(filp);
1258                        if (IS_ERR(sock)) {
1259                                ret = PTR_ERR(sock);
1260                                sock = NULL;
1261                                goto out;
1262                        }
1263
1264                        timeo = MAX_SCHEDULE_TIMEOUT;
1265                        ret = netlink_attachskb(sock, nc, &timeo, NULL);
1266                        if (ret == 1)
1267                                goto retry;
1268                        if (ret) {
1269                                sock = NULL;
1270                                nc = NULL;
1271                                goto out;
1272                        }
1273                }
1274        }
1275
1276        filp = fget(mqdes);
1277        if (!filp) {
1278                ret = -EBADF;
1279                goto out;
1280        }
1281
1282        inode = filp->f_path.dentry->d_inode;
1283        if (unlikely(filp->f_op != &mqueue_file_operations)) {
1284                ret = -EBADF;
1285                goto out_fput;
1286        }
1287        info = MQUEUE_I(inode);
1288
1289        ret = 0;
1290        spin_lock(&info->lock);
1291        if (u_notification == NULL) {
1292                if (info->notify_owner == task_tgid(current)) {
1293                        remove_notification(info);
1294                        inode->i_atime = inode->i_ctime = CURRENT_TIME;
1295                }
1296        } else if (info->notify_owner != NULL) {
1297                ret = -EBUSY;
1298        } else {
1299                switch (notification.sigev_notify) {
1300                case SIGEV_NONE:
1301                        info->notify.sigev_notify = SIGEV_NONE;
1302                        break;
1303                case SIGEV_THREAD:
1304                        info->notify_sock = sock;
1305                        info->notify_cookie = nc;
1306                        sock = NULL;
1307                        nc = NULL;
1308                        info->notify.sigev_notify = SIGEV_THREAD;
1309                        break;
1310                case SIGEV_SIGNAL:
1311                        info->notify.sigev_signo = notification.sigev_signo;
1312                        info->notify.sigev_value = notification.sigev_value;
1313                        info->notify.sigev_notify = SIGEV_SIGNAL;
1314                        break;
1315                }
1316
1317                info->notify_owner = get_pid(task_tgid(current));
1318                info->notify_user_ns = get_user_ns(current_user_ns());
1319                inode->i_atime = inode->i_ctime = CURRENT_TIME;
1320        }
1321        spin_unlock(&info->lock);
1322out_fput:
1323        fput(filp);
1324out:
1325        if (sock) {
1326                netlink_detachskb(sock, nc);
1327        } else if (nc) {
1328                dev_kfree_skb(nc);
1329        }
1330        return ret;
1331}
1332
1333SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1334                const struct mq_attr __user *, u_mqstat,
1335                struct mq_attr __user *, u_omqstat)
1336{
1337        int ret;
1338        struct mq_attr mqstat, omqstat;
1339        struct file *filp;
1340        struct inode *inode;
1341        struct mqueue_inode_info *info;
1342
1343        if (u_mqstat != NULL) {
1344                if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1345                        return -EFAULT;
1346                if (mqstat.mq_flags & (~O_NONBLOCK))
1347                        return -EINVAL;
1348        }
1349
1350        filp = fget(mqdes);
1351        if (!filp) {
1352                ret = -EBADF;
1353                goto out;
1354        }
1355
1356        inode = filp->f_path.dentry->d_inode;
1357        if (unlikely(filp->f_op != &mqueue_file_operations)) {
1358                ret = -EBADF;
1359                goto out_fput;
1360        }
1361        info = MQUEUE_I(inode);
1362
1363        spin_lock(&info->lock);
1364
1365        omqstat = info->attr;
1366        omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1367        if (u_mqstat) {
1368                audit_mq_getsetattr(mqdes, &mqstat);
1369                spin_lock(&filp->f_lock);
1370                if (mqstat.mq_flags & O_NONBLOCK)
1371                        filp->f_flags |= O_NONBLOCK;
1372                else
1373                        filp->f_flags &= ~O_NONBLOCK;
1374                spin_unlock(&filp->f_lock);
1375
1376                inode->i_atime = inode->i_ctime = CURRENT_TIME;
1377        }
1378
1379        spin_unlock(&info->lock);
1380
1381        ret = 0;
1382        if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1383                                                sizeof(struct mq_attr)))
1384                ret = -EFAULT;
1385
1386out_fput:
1387        fput(filp);
1388out:
1389        return ret;
1390}
1391
1392static const struct inode_operations mqueue_dir_inode_operations = {
1393        .lookup = simple_lookup,
1394        .create = mqueue_create,
1395        .unlink = mqueue_unlink,
1396};
1397
1398static const struct file_operations mqueue_file_operations = {
1399        .flush = mqueue_flush_file,
1400        .poll = mqueue_poll_file,
1401        .read = mqueue_read_file,
1402        .llseek = default_llseek,
1403};
1404
1405static const struct super_operations mqueue_super_ops = {
1406        .alloc_inode = mqueue_alloc_inode,
1407        .destroy_inode = mqueue_destroy_inode,
1408        .evict_inode = mqueue_evict_inode,
1409        .statfs = simple_statfs,
1410};
1411
1412static struct file_system_type mqueue_fs_type = {
1413        .name = "mqueue",
1414        .mount = mqueue_mount,
1415        .kill_sb = kill_litter_super,
1416};
1417
1418int mq_init_ns(struct ipc_namespace *ns)
1419{
1420        ns->mq_queues_count  = 0;
1421        ns->mq_queues_max    = DFLT_QUEUESMAX;
1422        ns->mq_msg_max       = DFLT_MSGMAX;
1423        ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1424        ns->mq_msg_default   = DFLT_MSG;
1425        ns->mq_msgsize_default  = DFLT_MSGSIZE;
1426
1427        ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1428        if (IS_ERR(ns->mq_mnt)) {
1429                int err = PTR_ERR(ns->mq_mnt);
1430                ns->mq_mnt = NULL;
1431                return err;
1432        }
1433        return 0;
1434}
1435
1436void mq_clear_sbinfo(struct ipc_namespace *ns)
1437{
1438        ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1439}
1440
1441void mq_put_mnt(struct ipc_namespace *ns)
1442{
1443        kern_unmount(ns->mq_mnt);
1444}
1445
1446static int __init init_mqueue_fs(void)
1447{
1448        int error;
1449
1450        mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1451                                sizeof(struct mqueue_inode_info), 0,
1452                                SLAB_HWCACHE_ALIGN, init_once);
1453        if (mqueue_inode_cachep == NULL)
1454                return -ENOMEM;
1455
1456        /* ignore failures - they are not fatal */
1457        mq_sysctl_table = mq_register_sysctl_table();
1458
1459        error = register_filesystem(&mqueue_fs_type);
1460        if (error)
1461                goto out_sysctl;
1462
1463        spin_lock_init(&mq_lock);
1464
1465        error = mq_init_ns(&init_ipc_ns);
1466        if (error)
1467                goto out_filesystem;
1468
1469        return 0;
1470
1471out_filesystem:
1472        unregister_filesystem(&mqueue_fs_type);
1473out_sysctl:
1474        if (mq_sysctl_table)
1475                unregister_sysctl_table(mq_sysctl_table);
1476        kmem_cache_destroy(mqueue_inode_cachep);
1477        return error;
1478}
1479
1480__initcall(init_mqueue_fs);
1481
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.