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