linux/ipc/msg.c
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   1/*
   2 * linux/ipc/msg.c
   3 * Copyright (C) 1992 Krishna Balasubramanian
   4 *
   5 * Removed all the remaining kerneld mess
   6 * Catch the -EFAULT stuff properly
   7 * Use GFP_KERNEL for messages as in 1.2
   8 * Fixed up the unchecked user space derefs
   9 * Copyright (C) 1998 Alan Cox & Andi Kleen
  10 *
  11 * /proc/sysvipc/msg support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
  12 *
  13 * mostly rewritten, threaded and wake-one semantics added
  14 * MSGMAX limit removed, sysctl's added
  15 * (c) 1999 Manfred Spraul <manfred@colorfullife.com>
  16 *
  17 * support for audit of ipc object properties and permission changes
  18 * Dustin Kirkland <dustin.kirkland@us.ibm.com>
  19 *
  20 * namespaces support
  21 * OpenVZ, SWsoft Inc.
  22 * Pavel Emelianov <xemul@openvz.org>
  23 */
  24
  25#include <linux/capability.h>
  26#include <linux/msg.h>
  27#include <linux/spinlock.h>
  28#include <linux/init.h>
  29#include <linux/mm.h>
  30#include <linux/proc_fs.h>
  31#include <linux/list.h>
  32#include <linux/security.h>
  33#include <linux/sched.h>
  34#include <linux/syscalls.h>
  35#include <linux/audit.h>
  36#include <linux/seq_file.h>
  37#include <linux/rwsem.h>
  38#include <linux/nsproxy.h>
  39#include <linux/ipc_namespace.h>
  40
  41#include <asm/current.h>
  42#include <asm/uaccess.h>
  43#include "util.h"
  44
  45/*
  46 * one msg_receiver structure for each sleeping receiver:
  47 */
  48struct msg_receiver {
  49        struct list_head        r_list;
  50        struct task_struct      *r_tsk;
  51
  52        int                     r_mode;
  53        long                    r_msgtype;
  54        long                    r_maxsize;
  55
  56        struct msg_msg          *volatile r_msg;
  57};
  58
  59/* one msg_sender for each sleeping sender */
  60struct msg_sender {
  61        struct list_head        list;
  62        struct task_struct      *tsk;
  63};
  64
  65#define SEARCH_ANY              1
  66#define SEARCH_EQUAL            2
  67#define SEARCH_NOTEQUAL         3
  68#define SEARCH_LESSEQUAL        4
  69
  70#define msg_ids(ns)     ((ns)->ids[IPC_MSG_IDS])
  71
  72#define msg_unlock(msq)         ipc_unlock(&(msq)->q_perm)
  73
  74static void freeque(struct ipc_namespace *, struct kern_ipc_perm *);
  75static int newque(struct ipc_namespace *, struct ipc_params *);
  76#ifdef CONFIG_PROC_FS
  77static int sysvipc_msg_proc_show(struct seq_file *s, void *it);
  78#endif
  79
  80/*
  81 * Scale msgmni with the available lowmem size: the memory dedicated to msg
  82 * queues should occupy at most 1/MSG_MEM_SCALE of lowmem.
  83 * Also take into account the number of nsproxies created so far.
  84 * This should be done staying within the (MSGMNI , IPCMNI/nr_ipc_ns) range.
  85 */
  86void recompute_msgmni(struct ipc_namespace *ns)
  87{
  88        struct sysinfo i;
  89        unsigned long allowed;
  90        int nb_ns;
  91
  92        si_meminfo(&i);
  93        allowed = (((i.totalram - i.totalhigh) / MSG_MEM_SCALE) * i.mem_unit)
  94                / MSGMNB;
  95        nb_ns = atomic_read(&nr_ipc_ns);
  96        allowed /= nb_ns;
  97
  98        if (allowed < MSGMNI) {
  99                ns->msg_ctlmni = MSGMNI;
 100                return;
 101        }
 102
 103        if (allowed > IPCMNI / nb_ns) {
 104                ns->msg_ctlmni = IPCMNI / nb_ns;
 105                return;
 106        }
 107
 108        ns->msg_ctlmni = allowed;
 109}
 110
 111void msg_init_ns(struct ipc_namespace *ns)
 112{
 113        ns->msg_ctlmax = MSGMAX;
 114        ns->msg_ctlmnb = MSGMNB;
 115
 116        recompute_msgmni(ns);
 117
 118        atomic_set(&ns->msg_bytes, 0);
 119        atomic_set(&ns->msg_hdrs, 0);
 120        ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
 121}
 122
 123#ifdef CONFIG_IPC_NS
 124void msg_exit_ns(struct ipc_namespace *ns)
 125{
 126        free_ipcs(ns, &msg_ids(ns), freeque);
 127        idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr);
 128}
 129#endif
 130
 131void __init msg_init(void)
 132{
 133        msg_init_ns(&init_ipc_ns);
 134
 135        printk(KERN_INFO "msgmni has been set to %d\n",
 136                init_ipc_ns.msg_ctlmni);
 137
 138        ipc_init_proc_interface("sysvipc/msg",
 139                                "       key      msqid perms      cbytes       qnum lspid lrpid   uid   gid  cuid  cgid      stime      rtime      ctime\n",
 140                                IPC_MSG_IDS, sysvipc_msg_proc_show);
 141}
 142
 143/*
 144 * msg_lock_(check_) routines are called in the paths where the rw_mutex
 145 * is not held.
 146 */
 147static inline struct msg_queue *msg_lock(struct ipc_namespace *ns, int id)
 148{
 149        struct kern_ipc_perm *ipcp = ipc_lock(&msg_ids(ns), id);
 150
 151        if (IS_ERR(ipcp))
 152                return (struct msg_queue *)ipcp;
 153
 154        return container_of(ipcp, struct msg_queue, q_perm);
 155}
 156
 157static inline struct msg_queue *msg_lock_check(struct ipc_namespace *ns,
 158                                                int id)
 159{
 160        struct kern_ipc_perm *ipcp = ipc_lock_check(&msg_ids(ns), id);
 161
 162        if (IS_ERR(ipcp))
 163                return (struct msg_queue *)ipcp;
 164
 165        return container_of(ipcp, struct msg_queue, q_perm);
 166}
 167
 168static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
 169{
 170        ipc_rmid(&msg_ids(ns), &s->q_perm);
 171}
 172
 173/**
 174 * newque - Create a new msg queue
 175 * @ns: namespace
 176 * @params: ptr to the structure that contains the key and msgflg
 177 *
 178 * Called with msg_ids.rw_mutex held (writer)
 179 */
 180static int newque(struct ipc_namespace *ns, struct ipc_params *params)
 181{
 182        struct msg_queue *msq;
 183        int id, retval;
 184        key_t key = params->key;
 185        int msgflg = params->flg;
 186
 187        msq = ipc_rcu_alloc(sizeof(*msq));
 188        if (!msq)
 189                return -ENOMEM;
 190
 191        msq->q_perm.mode = msgflg & S_IRWXUGO;
 192        msq->q_perm.key = key;
 193
 194        msq->q_perm.security = NULL;
 195        retval = security_msg_queue_alloc(msq);
 196        if (retval) {
 197                ipc_rcu_putref(msq);
 198                return retval;
 199        }
 200
 201        /*
 202         * ipc_addid() locks msq
 203         */
 204        id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
 205        if (id < 0) {
 206                security_msg_queue_free(msq);
 207                ipc_rcu_putref(msq);
 208                return id;
 209        }
 210
 211        msq->q_stime = msq->q_rtime = 0;
 212        msq->q_ctime = get_seconds();
 213        msq->q_cbytes = msq->q_qnum = 0;
 214        msq->q_qbytes = ns->msg_ctlmnb;
 215        msq->q_lspid = msq->q_lrpid = 0;
 216        INIT_LIST_HEAD(&msq->q_messages);
 217        INIT_LIST_HEAD(&msq->q_receivers);
 218        INIT_LIST_HEAD(&msq->q_senders);
 219
 220        msg_unlock(msq);
 221
 222        return msq->q_perm.id;
 223}
 224
 225static inline void ss_add(struct msg_queue *msq, struct msg_sender *mss)
 226{
 227        mss->tsk = current;
 228        current->state = TASK_INTERRUPTIBLE;
 229        list_add_tail(&mss->list, &msq->q_senders);
 230}
 231
 232static inline void ss_del(struct msg_sender *mss)
 233{
 234        if (mss->list.next != NULL)
 235                list_del(&mss->list);
 236}
 237
 238static void ss_wakeup(struct list_head *h, int kill)
 239{
 240        struct list_head *tmp;
 241
 242        tmp = h->next;
 243        while (tmp != h) {
 244                struct msg_sender *mss;
 245
 246                mss = list_entry(tmp, struct msg_sender, list);
 247                tmp = tmp->next;
 248                if (kill)
 249                        mss->list.next = NULL;
 250                wake_up_process(mss->tsk);
 251        }
 252}
 253
 254static void expunge_all(struct msg_queue *msq, int res)
 255{
 256        struct list_head *tmp;
 257
 258        tmp = msq->q_receivers.next;
 259        while (tmp != &msq->q_receivers) {
 260                struct msg_receiver *msr;
 261
 262                msr = list_entry(tmp, struct msg_receiver, r_list);
 263                tmp = tmp->next;
 264                msr->r_msg = NULL;
 265                wake_up_process(msr->r_tsk);
 266                smp_mb();
 267                msr->r_msg = ERR_PTR(res);
 268        }
 269}
 270
 271/*
 272 * freeque() wakes up waiters on the sender and receiver waiting queue,
 273 * removes the message queue from message queue ID IDR, and cleans up all the
 274 * messages associated with this queue.
 275 *
 276 * msg_ids.rw_mutex (writer) and the spinlock for this message queue are held
 277 * before freeque() is called. msg_ids.rw_mutex remains locked on exit.
 278 */
 279static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
 280{
 281        struct list_head *tmp;
 282        struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
 283
 284        expunge_all(msq, -EIDRM);
 285        ss_wakeup(&msq->q_senders, 1);
 286        msg_rmid(ns, msq);
 287        msg_unlock(msq);
 288
 289        tmp = msq->q_messages.next;
 290        while (tmp != &msq->q_messages) {
 291                struct msg_msg *msg = list_entry(tmp, struct msg_msg, m_list);
 292
 293                tmp = tmp->next;
 294                atomic_dec(&ns->msg_hdrs);
 295                free_msg(msg);
 296        }
 297        atomic_sub(msq->q_cbytes, &ns->msg_bytes);
 298        security_msg_queue_free(msq);
 299        ipc_rcu_putref(msq);
 300}
 301
 302/*
 303 * Called with msg_ids.rw_mutex and ipcp locked.
 304 */
 305static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg)
 306{
 307        struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
 308
 309        return security_msg_queue_associate(msq, msgflg);
 310}
 311
 312SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
 313{
 314        struct ipc_namespace *ns;
 315        struct ipc_ops msg_ops;
 316        struct ipc_params msg_params;
 317
 318        ns = current->nsproxy->ipc_ns;
 319
 320        msg_ops.getnew = newque;
 321        msg_ops.associate = msg_security;
 322        msg_ops.more_checks = NULL;
 323
 324        msg_params.key = key;
 325        msg_params.flg = msgflg;
 326
 327        return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params);
 328}
 329
 330static inline unsigned long
 331copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
 332{
 333        switch(version) {
 334        case IPC_64:
 335                return copy_to_user(buf, in, sizeof(*in));
 336        case IPC_OLD:
 337        {
 338                struct msqid_ds out;
 339
 340                memset(&out, 0, sizeof(out));
 341
 342                ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
 343
 344                out.msg_stime           = in->msg_stime;
 345                out.msg_rtime           = in->msg_rtime;
 346                out.msg_ctime           = in->msg_ctime;
 347
 348                if (in->msg_cbytes > USHRT_MAX)
 349                        out.msg_cbytes  = USHRT_MAX;
 350                else
 351                        out.msg_cbytes  = in->msg_cbytes;
 352                out.msg_lcbytes         = in->msg_cbytes;
 353
 354                if (in->msg_qnum > USHRT_MAX)
 355                        out.msg_qnum    = USHRT_MAX;
 356                else
 357                        out.msg_qnum    = in->msg_qnum;
 358
 359                if (in->msg_qbytes > USHRT_MAX)
 360                        out.msg_qbytes  = USHRT_MAX;
 361                else
 362                        out.msg_qbytes  = in->msg_qbytes;
 363                out.msg_lqbytes         = in->msg_qbytes;
 364
 365                out.msg_lspid           = in->msg_lspid;
 366                out.msg_lrpid           = in->msg_lrpid;
 367
 368                return copy_to_user(buf, &out, sizeof(out));
 369        }
 370        default:
 371                return -EINVAL;
 372        }
 373}
 374
 375static inline unsigned long
 376copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version)
 377{
 378        switch(version) {
 379        case IPC_64:
 380                if (copy_from_user(out, buf, sizeof(*out)))
 381                        return -EFAULT;
 382                return 0;
 383        case IPC_OLD:
 384        {
 385                struct msqid_ds tbuf_old;
 386
 387                if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 388                        return -EFAULT;
 389
 390                out->msg_perm.uid       = tbuf_old.msg_perm.uid;
 391                out->msg_perm.gid       = tbuf_old.msg_perm.gid;
 392                out->msg_perm.mode      = tbuf_old.msg_perm.mode;
 393
 394                if (tbuf_old.msg_qbytes == 0)
 395                        out->msg_qbytes = tbuf_old.msg_lqbytes;
 396                else
 397                        out->msg_qbytes = tbuf_old.msg_qbytes;
 398
 399                return 0;
 400        }
 401        default:
 402                return -EINVAL;
 403        }
 404}
 405
 406/*
 407 * This function handles some msgctl commands which require the rw_mutex
 408 * to be held in write mode.
 409 * NOTE: no locks must be held, the rw_mutex is taken inside this function.
 410 */
 411static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
 412                       struct msqid_ds __user *buf, int version)
 413{
 414        struct kern_ipc_perm *ipcp;
 415        struct msqid64_ds uninitialized_var(msqid64);
 416        struct msg_queue *msq;
 417        int err;
 418
 419        if (cmd == IPC_SET) {
 420                if (copy_msqid_from_user(&msqid64, buf, version))
 421                        return -EFAULT;
 422        }
 423
 424        ipcp = ipcctl_pre_down(ns, &msg_ids(ns), msqid, cmd,
 425                               &msqid64.msg_perm, msqid64.msg_qbytes);
 426        if (IS_ERR(ipcp))
 427                return PTR_ERR(ipcp);
 428
 429        msq = container_of(ipcp, struct msg_queue, q_perm);
 430
 431        err = security_msg_queue_msgctl(msq, cmd);
 432        if (err)
 433                goto out_unlock;
 434
 435        switch (cmd) {
 436        case IPC_RMID:
 437                freeque(ns, ipcp);
 438                goto out_up;
 439        case IPC_SET:
 440                if (msqid64.msg_qbytes > ns->msg_ctlmnb &&
 441                    !capable(CAP_SYS_RESOURCE)) {
 442                        err = -EPERM;
 443                        goto out_unlock;
 444                }
 445
 446                err = ipc_update_perm(&msqid64.msg_perm, ipcp);
 447                if (err)
 448                        goto out_unlock;
 449
 450                msq->q_qbytes = msqid64.msg_qbytes;
 451
 452                msq->q_ctime = get_seconds();
 453                /* sleeping receivers might be excluded by
 454                 * stricter permissions.
 455                 */
 456                expunge_all(msq, -EAGAIN);
 457                /* sleeping senders might be able to send
 458                 * due to a larger queue size.
 459                 */
 460                ss_wakeup(&msq->q_senders, 0);
 461                break;
 462        default:
 463                err = -EINVAL;
 464        }
 465out_unlock:
 466        msg_unlock(msq);
 467out_up:
 468        up_write(&msg_ids(ns).rw_mutex);
 469        return err;
 470}
 471
 472SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
 473{
 474        struct msg_queue *msq;
 475        int err, version;
 476        struct ipc_namespace *ns;
 477
 478        if (msqid < 0 || cmd < 0)
 479                return -EINVAL;
 480
 481        version = ipc_parse_version(&cmd);
 482        ns = current->nsproxy->ipc_ns;
 483
 484        switch (cmd) {
 485        case IPC_INFO:
 486        case MSG_INFO:
 487        {
 488                struct msginfo msginfo;
 489                int max_id;
 490
 491                if (!buf)
 492                        return -EFAULT;
 493                /*
 494                 * We must not return kernel stack data.
 495                 * due to padding, it's not enough
 496                 * to set all member fields.
 497                 */
 498                err = security_msg_queue_msgctl(NULL, cmd);
 499                if (err)
 500                        return err;
 501
 502                memset(&msginfo, 0, sizeof(msginfo));
 503                msginfo.msgmni = ns->msg_ctlmni;
 504                msginfo.msgmax = ns->msg_ctlmax;
 505                msginfo.msgmnb = ns->msg_ctlmnb;
 506                msginfo.msgssz = MSGSSZ;
 507                msginfo.msgseg = MSGSEG;
 508                down_read(&msg_ids(ns).rw_mutex);
 509                if (cmd == MSG_INFO) {
 510                        msginfo.msgpool = msg_ids(ns).in_use;
 511                        msginfo.msgmap = atomic_read(&ns->msg_hdrs);
 512                        msginfo.msgtql = atomic_read(&ns->msg_bytes);
 513                } else {
 514                        msginfo.msgmap = MSGMAP;
 515                        msginfo.msgpool = MSGPOOL;
 516                        msginfo.msgtql = MSGTQL;
 517                }
 518                max_id = ipc_get_maxid(&msg_ids(ns));
 519                up_read(&msg_ids(ns).rw_mutex);
 520                if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
 521                        return -EFAULT;
 522                return (max_id < 0) ? 0 : max_id;
 523        }
 524        case MSG_STAT:  /* msqid is an index rather than a msg queue id */
 525        case IPC_STAT:
 526        {
 527                struct msqid64_ds tbuf;
 528                int success_return;
 529
 530                if (!buf)
 531                        return -EFAULT;
 532
 533                if (cmd == MSG_STAT) {
 534                        msq = msg_lock(ns, msqid);
 535                        if (IS_ERR(msq))
 536                                return PTR_ERR(msq);
 537                        success_return = msq->q_perm.id;
 538                } else {
 539                        msq = msg_lock_check(ns, msqid);
 540                        if (IS_ERR(msq))
 541                                return PTR_ERR(msq);
 542                        success_return = 0;
 543                }
 544                err = -EACCES;
 545                if (ipcperms(ns, &msq->q_perm, S_IRUGO))
 546                        goto out_unlock;
 547
 548                err = security_msg_queue_msgctl(msq, cmd);
 549                if (err)
 550                        goto out_unlock;
 551
 552                memset(&tbuf, 0, sizeof(tbuf));
 553
 554                kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm);
 555                tbuf.msg_stime  = msq->q_stime;
 556                tbuf.msg_rtime  = msq->q_rtime;
 557                tbuf.msg_ctime  = msq->q_ctime;
 558                tbuf.msg_cbytes = msq->q_cbytes;
 559                tbuf.msg_qnum   = msq->q_qnum;
 560                tbuf.msg_qbytes = msq->q_qbytes;
 561                tbuf.msg_lspid  = msq->q_lspid;
 562                tbuf.msg_lrpid  = msq->q_lrpid;
 563                msg_unlock(msq);
 564                if (copy_msqid_to_user(buf, &tbuf, version))
 565                        return -EFAULT;
 566                return success_return;
 567        }
 568        case IPC_SET:
 569        case IPC_RMID:
 570                err = msgctl_down(ns, msqid, cmd, buf, version);
 571                return err;
 572        default:
 573                return  -EINVAL;
 574        }
 575
 576out_unlock:
 577        msg_unlock(msq);
 578        return err;
 579}
 580
 581static int testmsg(struct msg_msg *msg, long type, int mode)
 582{
 583        switch(mode)
 584        {
 585                case SEARCH_ANY:
 586                        return 1;
 587                case SEARCH_LESSEQUAL:
 588                        if (msg->m_type <=type)
 589                                return 1;
 590                        break;
 591                case SEARCH_EQUAL:
 592                        if (msg->m_type == type)
 593                                return 1;
 594                        break;
 595                case SEARCH_NOTEQUAL:
 596                        if (msg->m_type != type)
 597                                return 1;
 598                        break;
 599        }
 600        return 0;
 601}
 602
 603static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg)
 604{
 605        struct list_head *tmp;
 606
 607        tmp = msq->q_receivers.next;
 608        while (tmp != &msq->q_receivers) {
 609                struct msg_receiver *msr;
 610
 611                msr = list_entry(tmp, struct msg_receiver, r_list);
 612                tmp = tmp->next;
 613                if (testmsg(msg, msr->r_msgtype, msr->r_mode) &&
 614                    !security_msg_queue_msgrcv(msq, msg, msr->r_tsk,
 615                                               msr->r_msgtype, msr->r_mode)) {
 616
 617                        list_del(&msr->r_list);
 618                        if (msr->r_maxsize < msg->m_ts) {
 619                                msr->r_msg = NULL;
 620                                wake_up_process(msr->r_tsk);
 621                                smp_mb();
 622                                msr->r_msg = ERR_PTR(-E2BIG);
 623                        } else {
 624                                msr->r_msg = NULL;
 625                                msq->q_lrpid = task_pid_vnr(msr->r_tsk);
 626                                msq->q_rtime = get_seconds();
 627                                wake_up_process(msr->r_tsk);
 628                                smp_mb();
 629                                msr->r_msg = msg;
 630
 631                                return 1;
 632                        }
 633                }
 634        }
 635        return 0;
 636}
 637
 638long do_msgsnd(int msqid, long mtype, void __user *mtext,
 639                size_t msgsz, int msgflg)
 640{
 641        struct msg_queue *msq;
 642        struct msg_msg *msg;
 643        int err;
 644        struct ipc_namespace *ns;
 645
 646        ns = current->nsproxy->ipc_ns;
 647
 648        if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0)
 649                return -EINVAL;
 650        if (mtype < 1)
 651                return -EINVAL;
 652
 653        msg = load_msg(mtext, msgsz);
 654        if (IS_ERR(msg))
 655                return PTR_ERR(msg);
 656
 657        msg->m_type = mtype;
 658        msg->m_ts = msgsz;
 659
 660        msq = msg_lock_check(ns, msqid);
 661        if (IS_ERR(msq)) {
 662                err = PTR_ERR(msq);
 663                goto out_free;
 664        }
 665
 666        for (;;) {
 667                struct msg_sender s;
 668
 669                err = -EACCES;
 670                if (ipcperms(ns, &msq->q_perm, S_IWUGO))
 671                        goto out_unlock_free;
 672
 673                err = security_msg_queue_msgsnd(msq, msg, msgflg);
 674                if (err)
 675                        goto out_unlock_free;
 676
 677                if (msgsz + msq->q_cbytes <= msq->q_qbytes &&
 678                                1 + msq->q_qnum <= msq->q_qbytes) {
 679                        break;
 680                }
 681
 682                /* queue full, wait: */
 683                if (msgflg & IPC_NOWAIT) {
 684                        err = -EAGAIN;
 685                        goto out_unlock_free;
 686                }
 687                ss_add(msq, &s);
 688                ipc_rcu_getref(msq);
 689                msg_unlock(msq);
 690                schedule();
 691
 692                ipc_lock_by_ptr(&msq->q_perm);
 693                ipc_rcu_putref(msq);
 694                if (msq->q_perm.deleted) {
 695                        err = -EIDRM;
 696                        goto out_unlock_free;
 697                }
 698                ss_del(&s);
 699
 700                if (signal_pending(current)) {
 701                        err = -ERESTARTNOHAND;
 702                        goto out_unlock_free;
 703                }
 704        }
 705
 706        msq->q_lspid = task_tgid_vnr(current);
 707        msq->q_stime = get_seconds();
 708
 709        if (!pipelined_send(msq, msg)) {
 710                /* no one is waiting for this message, enqueue it */
 711                list_add_tail(&msg->m_list, &msq->q_messages);
 712                msq->q_cbytes += msgsz;
 713                msq->q_qnum++;
 714                atomic_add(msgsz, &ns->msg_bytes);
 715                atomic_inc(&ns->msg_hdrs);
 716        }
 717
 718        err = 0;
 719        msg = NULL;
 720
 721out_unlock_free:
 722        msg_unlock(msq);
 723out_free:
 724        if (msg != NULL)
 725                free_msg(msg);
 726        return err;
 727}
 728
 729SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
 730                int, msgflg)
 731{
 732        long mtype;
 733
 734        if (get_user(mtype, &msgp->mtype))
 735                return -EFAULT;
 736        return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg);
 737}
 738
 739static inline int convert_mode(long *msgtyp, int msgflg)
 740{
 741        /*
 742         *  find message of correct type.
 743         *  msgtyp = 0 => get first.
 744         *  msgtyp > 0 => get first message of matching type.
 745         *  msgtyp < 0 => get message with least type must be < abs(msgtype).
 746         */
 747        if (*msgtyp == 0)
 748                return SEARCH_ANY;
 749        if (*msgtyp < 0) {
 750                *msgtyp = -*msgtyp;
 751                return SEARCH_LESSEQUAL;
 752        }
 753        if (msgflg & MSG_EXCEPT)
 754                return SEARCH_NOTEQUAL;
 755        return SEARCH_EQUAL;
 756}
 757
 758static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
 759{
 760        struct msgbuf __user *msgp = dest;
 761        size_t msgsz;
 762
 763        if (put_user(msg->m_type, &msgp->mtype))
 764                return -EFAULT;
 765
 766        msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
 767        if (store_msg(msgp->mtext, msg, msgsz))
 768                return -EFAULT;
 769        return msgsz;
 770}
 771
 772#ifdef CONFIG_CHECKPOINT_RESTORE
 773/*
 774 * This function creates new kernel message structure, large enough to store
 775 * bufsz message bytes.
 776 */
 777static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz,
 778                                           int msgflg, long *msgtyp,
 779                                           unsigned long *copy_number)
 780{
 781        struct msg_msg *copy;
 782
 783        *copy_number = *msgtyp;
 784        *msgtyp = 0;
 785        /*
 786         * Create dummy message to copy real message to.
 787         */
 788        copy = load_msg(buf, bufsz);
 789        if (!IS_ERR(copy))
 790                copy->m_ts = bufsz;
 791        return copy;
 792}
 793
 794static inline void free_copy(struct msg_msg *copy)
 795{
 796        if (copy)
 797                free_msg(copy);
 798}
 799#else
 800static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz,
 801                                           int msgflg, long *msgtyp,
 802                                           unsigned long *copy_number)
 803{
 804        return ERR_PTR(-ENOSYS);
 805}
 806
 807static inline void free_copy(struct msg_msg *copy)
 808{
 809}
 810#endif
 811
 812long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp,
 813               int msgflg,
 814               long (*msg_handler)(void __user *, struct msg_msg *, size_t))
 815{
 816        struct msg_queue *msq;
 817        struct msg_msg *msg;
 818        int mode;
 819        struct ipc_namespace *ns;
 820        struct msg_msg *copy = NULL;
 821        unsigned long copy_number = 0;
 822
 823        if (msqid < 0 || (long) bufsz < 0)
 824                return -EINVAL;
 825        if (msgflg & MSG_COPY) {
 826                copy = prepare_copy(buf, bufsz, msgflg, &msgtyp, &copy_number);
 827                if (IS_ERR(copy))
 828                        return PTR_ERR(copy);
 829        }
 830        mode = convert_mode(&msgtyp, msgflg);
 831        ns = current->nsproxy->ipc_ns;
 832
 833        msq = msg_lock_check(ns, msqid);
 834        if (IS_ERR(msq)) {
 835                free_copy(copy);
 836                return PTR_ERR(msq);
 837        }
 838
 839        for (;;) {
 840                struct msg_receiver msr_d;
 841                struct list_head *tmp;
 842                long msg_counter = 0;
 843
 844                msg = ERR_PTR(-EACCES);
 845                if (ipcperms(ns, &msq->q_perm, S_IRUGO))
 846                        goto out_unlock;
 847
 848                msg = ERR_PTR(-EAGAIN);
 849                tmp = msq->q_messages.next;
 850                while (tmp != &msq->q_messages) {
 851                        struct msg_msg *walk_msg;
 852
 853                        walk_msg = list_entry(tmp, struct msg_msg, m_list);
 854                        if (testmsg(walk_msg, msgtyp, mode) &&
 855                            !security_msg_queue_msgrcv(msq, walk_msg, current,
 856                                                       msgtyp, mode)) {
 857
 858                                msg = walk_msg;
 859                                if (mode == SEARCH_LESSEQUAL &&
 860                                                walk_msg->m_type != 1) {
 861                                        msgtyp = walk_msg->m_type - 1;
 862                                } else if (msgflg & MSG_COPY) {
 863                                        if (copy_number == msg_counter) {
 864                                                /*
 865                                                 * Found requested message.
 866                                                 * Copy it.
 867                                                 */
 868                                                msg = copy_msg(msg, copy);
 869                                                if (IS_ERR(msg))
 870                                                        goto out_unlock;
 871                                                break;
 872                                        }
 873                                } else
 874                                        break;
 875                                msg_counter++;
 876                        }
 877                        tmp = tmp->next;
 878                }
 879                if (!IS_ERR(msg)) {
 880                        /*
 881                         * Found a suitable message.
 882                         * Unlink it from the queue.
 883                         */
 884                        if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
 885                                msg = ERR_PTR(-E2BIG);
 886                                goto out_unlock;
 887                        }
 888                        /*
 889                         * If we are copying, then do not unlink message and do
 890                         * not update queue parameters.
 891                         */
 892                        if (msgflg & MSG_COPY)
 893                                goto out_unlock;
 894                        list_del(&msg->m_list);
 895                        msq->q_qnum--;
 896                        msq->q_rtime = get_seconds();
 897                        msq->q_lrpid = task_tgid_vnr(current);
 898                        msq->q_cbytes -= msg->m_ts;
 899                        atomic_sub(msg->m_ts, &ns->msg_bytes);
 900                        atomic_dec(&ns->msg_hdrs);
 901                        ss_wakeup(&msq->q_senders, 0);
 902                        msg_unlock(msq);
 903                        break;
 904                }
 905                /* No message waiting. Wait for a message */
 906                if (msgflg & IPC_NOWAIT) {
 907                        msg = ERR_PTR(-ENOMSG);
 908                        goto out_unlock;
 909                }
 910                list_add_tail(&msr_d.r_list, &msq->q_receivers);
 911                msr_d.r_tsk = current;
 912                msr_d.r_msgtype = msgtyp;
 913                msr_d.r_mode = mode;
 914                if (msgflg & MSG_NOERROR)
 915                        msr_d.r_maxsize = INT_MAX;
 916                else
 917                        msr_d.r_maxsize = bufsz;
 918                msr_d.r_msg = ERR_PTR(-EAGAIN);
 919                current->state = TASK_INTERRUPTIBLE;
 920                msg_unlock(msq);
 921
 922                schedule();
 923
 924                /* Lockless receive, part 1:
 925                 * Disable preemption.  We don't hold a reference to the queue
 926                 * and getting a reference would defeat the idea of a lockless
 927                 * operation, thus the code relies on rcu to guarantee the
 928                 * existence of msq:
 929                 * Prior to destruction, expunge_all(-EIRDM) changes r_msg.
 930                 * Thus if r_msg is -EAGAIN, then the queue not yet destroyed.
 931                 * rcu_read_lock() prevents preemption between reading r_msg
 932                 * and the spin_lock() inside ipc_lock_by_ptr().
 933                 */
 934                rcu_read_lock();
 935
 936                /* Lockless receive, part 2:
 937                 * Wait until pipelined_send or expunge_all are outside of
 938                 * wake_up_process(). There is a race with exit(), see
 939                 * ipc/mqueue.c for the details.
 940                 */
 941                msg = (struct msg_msg*)msr_d.r_msg;
 942                while (msg == NULL) {
 943                        cpu_relax();
 944                        msg = (struct msg_msg *)msr_d.r_msg;
 945                }
 946
 947                /* Lockless receive, part 3:
 948                 * If there is a message or an error then accept it without
 949                 * locking.
 950                 */
 951                if (msg != ERR_PTR(-EAGAIN)) {
 952                        rcu_read_unlock();
 953                        break;
 954                }
 955
 956                /* Lockless receive, part 3:
 957                 * Acquire the queue spinlock.
 958                 */
 959                ipc_lock_by_ptr(&msq->q_perm);
 960                rcu_read_unlock();
 961
 962                /* Lockless receive, part 4:
 963                 * Repeat test after acquiring the spinlock.
 964                 */
 965                msg = (struct msg_msg*)msr_d.r_msg;
 966                if (msg != ERR_PTR(-EAGAIN))
 967                        goto out_unlock;
 968
 969                list_del(&msr_d.r_list);
 970                if (signal_pending(current)) {
 971                        msg = ERR_PTR(-ERESTARTNOHAND);
 972out_unlock:
 973                        msg_unlock(msq);
 974                        break;
 975                }
 976        }
 977        if (IS_ERR(msg)) {
 978                free_copy(copy);
 979                return PTR_ERR(msg);
 980        }
 981
 982        bufsz = msg_handler(buf, msg, bufsz);
 983        free_msg(msg);
 984
 985        return bufsz;
 986}
 987
 988SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
 989                long, msgtyp, int, msgflg)
 990{
 991        return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill);
 992}
 993
 994#ifdef CONFIG_PROC_FS
 995static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
 996{
 997        struct user_namespace *user_ns = seq_user_ns(s);
 998        struct msg_queue *msq = it;
 999
1000        return seq_printf(s,
1001                        "%10d %10d  %4o  %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu\n",
1002                        msq->q_perm.key,
1003                        msq->q_perm.id,
1004                        msq->q_perm.mode,
1005                        msq->q_cbytes,
1006                        msq->q_qnum,
1007                        msq->q_lspid,
1008                        msq->q_lrpid,
1009                        from_kuid_munged(user_ns, msq->q_perm.uid),
1010                        from_kgid_munged(user_ns, msq->q_perm.gid),
1011                        from_kuid_munged(user_ns, msq->q_perm.cuid),
1012                        from_kgid_munged(user_ns, msq->q_perm.cgid),
1013                        msq->q_stime,
1014                        msq->q_rtime,
1015                        msq->q_ctime);
1016}
1017#endif
1018
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