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#define SEARCH_NUMBER           5
  70
  71#define msg_ids(ns)     ((ns)->ids[IPC_MSG_IDS])
  72
  73#define msg_unlock(msq)         ipc_unlock(&(msq)->q_perm)
  74
  75static void freeque(struct ipc_namespace *, struct kern_ipc_perm *);
  76static int newque(struct ipc_namespace *, struct ipc_params *);
  77#ifdef CONFIG_PROC_FS
  78static int sysvipc_msg_proc_show(struct seq_file *s, void *it);
  79#endif
  80
  81/*
  82 * Scale msgmni with the available lowmem size: the memory dedicated to msg
  83 * queues should occupy at most 1/MSG_MEM_SCALE of lowmem.
  84 * Also take into account the number of nsproxies created so far.
  85 * This should be done staying within the (MSGMNI , IPCMNI/nr_ipc_ns) range.
  86 */
  87void recompute_msgmni(struct ipc_namespace *ns)
  88{
  89        struct sysinfo i;
  90        unsigned long allowed;
  91        int nb_ns;
  92
  93        si_meminfo(&i);
  94        allowed = (((i.totalram - i.totalhigh) / MSG_MEM_SCALE) * i.mem_unit)
  95                / MSGMNB;
  96        nb_ns = atomic_read(&nr_ipc_ns);
  97        allowed /= nb_ns;
  98
  99        if (allowed < MSGMNI) {
 100                ns->msg_ctlmni = MSGMNI;
 101                return;
 102        }
 103
 104        if (allowed > IPCMNI / nb_ns) {
 105                ns->msg_ctlmni = IPCMNI / nb_ns;
 106                return;
 107        }
 108
 109        ns->msg_ctlmni = allowed;
 110}
 111
 112void msg_init_ns(struct ipc_namespace *ns)
 113{
 114        ns->msg_ctlmax = MSGMAX;
 115        ns->msg_ctlmnb = MSGMNB;
 116
 117        recompute_msgmni(ns);
 118
 119        atomic_set(&ns->msg_bytes, 0);
 120        atomic_set(&ns->msg_hdrs, 0);
 121        ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
 122}
 123
 124#ifdef CONFIG_IPC_NS
 125void msg_exit_ns(struct ipc_namespace *ns)
 126{
 127        free_ipcs(ns, &msg_ids(ns), freeque);
 128        idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr);
 129}
 130#endif
 131
 132void __init msg_init(void)
 133{
 134        msg_init_ns(&init_ipc_ns);
 135
 136        printk(KERN_INFO "msgmni has been set to %d\n",
 137                init_ipc_ns.msg_ctlmni);
 138
 139        ipc_init_proc_interface("sysvipc/msg",
 140                                "       key      msqid perms      cbytes       qnum lspid lrpid   uid   gid  cuid  cgid      stime      rtime      ctime\n",
 141                                IPC_MSG_IDS, sysvipc_msg_proc_show);
 142}
 143
 144static inline struct msg_queue *msq_obtain_object(struct ipc_namespace *ns, int id)
 145{
 146        struct kern_ipc_perm *ipcp = ipc_obtain_object(&msg_ids(ns), id);
 147
 148        if (IS_ERR(ipcp))
 149                return ERR_CAST(ipcp);
 150
 151        return container_of(ipcp, struct msg_queue, q_perm);
 152}
 153
 154static inline struct msg_queue *msq_obtain_object_check(struct ipc_namespace *ns,
 155                                                        int id)
 156{
 157        struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&msg_ids(ns), id);
 158
 159        if (IS_ERR(ipcp))
 160                return ERR_CAST(ipcp);
 161
 162        return container_of(ipcp, struct msg_queue, q_perm);
 163}
 164
 165static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
 166{
 167        ipc_rmid(&msg_ids(ns), &s->q_perm);
 168}
 169
 170/**
 171 * newque - Create a new msg queue
 172 * @ns: namespace
 173 * @params: ptr to the structure that contains the key and msgflg
 174 *
 175 * Called with msg_ids.rw_mutex held (writer)
 176 */
 177static int newque(struct ipc_namespace *ns, struct ipc_params *params)
 178{
 179        struct msg_queue *msq;
 180        int id, retval;
 181        key_t key = params->key;
 182        int msgflg = params->flg;
 183
 184        msq = ipc_rcu_alloc(sizeof(*msq));
 185        if (!msq)
 186                return -ENOMEM;
 187
 188        msq->q_perm.mode = msgflg & S_IRWXUGO;
 189        msq->q_perm.key = key;
 190
 191        msq->q_perm.security = NULL;
 192        retval = security_msg_queue_alloc(msq);
 193        if (retval) {
 194                ipc_rcu_putref(msq);
 195                return retval;
 196        }
 197
 198        /* ipc_addid() locks msq upon success. */
 199        id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
 200        if (id < 0) {
 201                security_msg_queue_free(msq);
 202                ipc_rcu_putref(msq);
 203                return id;
 204        }
 205
 206        msq->q_stime = msq->q_rtime = 0;
 207        msq->q_ctime = get_seconds();
 208        msq->q_cbytes = msq->q_qnum = 0;
 209        msq->q_qbytes = ns->msg_ctlmnb;
 210        msq->q_lspid = msq->q_lrpid = 0;
 211        INIT_LIST_HEAD(&msq->q_messages);
 212        INIT_LIST_HEAD(&msq->q_receivers);
 213        INIT_LIST_HEAD(&msq->q_senders);
 214
 215        ipc_unlock_object(&msq->q_perm);
 216        rcu_read_unlock();
 217
 218        return msq->q_perm.id;
 219}
 220
 221static inline void ss_add(struct msg_queue *msq, struct msg_sender *mss)
 222{
 223        mss->tsk = current;
 224        current->state = TASK_INTERRUPTIBLE;
 225        list_add_tail(&mss->list, &msq->q_senders);
 226}
 227
 228static inline void ss_del(struct msg_sender *mss)
 229{
 230        if (mss->list.next != NULL)
 231                list_del(&mss->list);
 232}
 233
 234static void ss_wakeup(struct list_head *h, int kill)
 235{
 236        struct msg_sender *mss, *t;
 237
 238        list_for_each_entry_safe(mss, t, h, list) {
 239                if (kill)
 240                        mss->list.next = NULL;
 241                wake_up_process(mss->tsk);
 242        }
 243}
 244
 245static void expunge_all(struct msg_queue *msq, int res)
 246{
 247        struct msg_receiver *msr, *t;
 248
 249        list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
 250                msr->r_msg = NULL;
 251                wake_up_process(msr->r_tsk);
 252                smp_mb();
 253                msr->r_msg = ERR_PTR(res);
 254        }
 255}
 256
 257/*
 258 * freeque() wakes up waiters on the sender and receiver waiting queue,
 259 * removes the message queue from message queue ID IDR, and cleans up all the
 260 * messages associated with this queue.
 261 *
 262 * msg_ids.rw_mutex (writer) and the spinlock for this message queue are held
 263 * before freeque() is called. msg_ids.rw_mutex remains locked on exit.
 264 */
 265static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
 266{
 267        struct msg_msg *msg, *t;
 268        struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
 269
 270        expunge_all(msq, -EIDRM);
 271        ss_wakeup(&msq->q_senders, 1);
 272        msg_rmid(ns, msq);
 273        msg_unlock(msq);
 274
 275        list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) {
 276                atomic_dec(&ns->msg_hdrs);
 277                free_msg(msg);
 278        }
 279        atomic_sub(msq->q_cbytes, &ns->msg_bytes);
 280        security_msg_queue_free(msq);
 281        ipc_rcu_putref(msq);
 282}
 283
 284/*
 285 * Called with msg_ids.rw_mutex and ipcp locked.
 286 */
 287static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg)
 288{
 289        struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
 290
 291        return security_msg_queue_associate(msq, msgflg);
 292}
 293
 294SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
 295{
 296        struct ipc_namespace *ns;
 297        struct ipc_ops msg_ops;
 298        struct ipc_params msg_params;
 299
 300        ns = current->nsproxy->ipc_ns;
 301
 302        msg_ops.getnew = newque;
 303        msg_ops.associate = msg_security;
 304        msg_ops.more_checks = NULL;
 305
 306        msg_params.key = key;
 307        msg_params.flg = msgflg;
 308
 309        return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params);
 310}
 311
 312static inline unsigned long
 313copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
 314{
 315        switch(version) {
 316        case IPC_64:
 317                return copy_to_user(buf, in, sizeof(*in));
 318        case IPC_OLD:
 319        {
 320                struct msqid_ds out;
 321
 322                memset(&out, 0, sizeof(out));
 323
 324                ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
 325
 326                out.msg_stime           = in->msg_stime;
 327                out.msg_rtime           = in->msg_rtime;
 328                out.msg_ctime           = in->msg_ctime;
 329
 330                if (in->msg_cbytes > USHRT_MAX)
 331                        out.msg_cbytes  = USHRT_MAX;
 332                else
 333                        out.msg_cbytes  = in->msg_cbytes;
 334                out.msg_lcbytes         = in->msg_cbytes;
 335
 336                if (in->msg_qnum > USHRT_MAX)
 337                        out.msg_qnum    = USHRT_MAX;
 338                else
 339                        out.msg_qnum    = in->msg_qnum;
 340
 341                if (in->msg_qbytes > USHRT_MAX)
 342                        out.msg_qbytes  = USHRT_MAX;
 343                else
 344                        out.msg_qbytes  = in->msg_qbytes;
 345                out.msg_lqbytes         = in->msg_qbytes;
 346
 347                out.msg_lspid           = in->msg_lspid;
 348                out.msg_lrpid           = in->msg_lrpid;
 349
 350                return copy_to_user(buf, &out, sizeof(out));
 351        }
 352        default:
 353                return -EINVAL;
 354        }
 355}
 356
 357static inline unsigned long
 358copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version)
 359{
 360        switch(version) {
 361        case IPC_64:
 362                if (copy_from_user(out, buf, sizeof(*out)))
 363                        return -EFAULT;
 364                return 0;
 365        case IPC_OLD:
 366        {
 367                struct msqid_ds tbuf_old;
 368
 369                if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 370                        return -EFAULT;
 371
 372                out->msg_perm.uid       = tbuf_old.msg_perm.uid;
 373                out->msg_perm.gid       = tbuf_old.msg_perm.gid;
 374                out->msg_perm.mode      = tbuf_old.msg_perm.mode;
 375
 376                if (tbuf_old.msg_qbytes == 0)
 377                        out->msg_qbytes = tbuf_old.msg_lqbytes;
 378                else
 379                        out->msg_qbytes = tbuf_old.msg_qbytes;
 380
 381                return 0;
 382        }
 383        default:
 384                return -EINVAL;
 385        }
 386}
 387
 388/*
 389 * This function handles some msgctl commands which require the rw_mutex
 390 * to be held in write mode.
 391 * NOTE: no locks must be held, the rw_mutex is taken inside this function.
 392 */
 393static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
 394                       struct msqid_ds __user *buf, int version)
 395{
 396        struct kern_ipc_perm *ipcp;
 397        struct msqid64_ds uninitialized_var(msqid64);
 398        struct msg_queue *msq;
 399        int err;
 400
 401        if (cmd == IPC_SET) {
 402                if (copy_msqid_from_user(&msqid64, buf, version))
 403                        return -EFAULT;
 404        }
 405
 406        down_write(&msg_ids(ns).rw_mutex);
 407        rcu_read_lock();
 408
 409        ipcp = ipcctl_pre_down_nolock(ns, &msg_ids(ns), msqid, cmd,
 410                                      &msqid64.msg_perm, msqid64.msg_qbytes);
 411        if (IS_ERR(ipcp)) {
 412                err = PTR_ERR(ipcp);
 413                goto out_unlock1;
 414        }
 415
 416        msq = container_of(ipcp, struct msg_queue, q_perm);
 417
 418        err = security_msg_queue_msgctl(msq, cmd);
 419        if (err)
 420                goto out_unlock1;
 421
 422        switch (cmd) {
 423        case IPC_RMID:
 424                ipc_lock_object(&msq->q_perm);
 425                /* freeque unlocks the ipc object and rcu */
 426                freeque(ns, ipcp);
 427                goto out_up;
 428        case IPC_SET:
 429                if (msqid64.msg_qbytes > ns->msg_ctlmnb &&
 430                    !capable(CAP_SYS_RESOURCE)) {
 431                        err = -EPERM;
 432                        goto out_unlock1;
 433                }
 434
 435                ipc_lock_object(&msq->q_perm);
 436                err = ipc_update_perm(&msqid64.msg_perm, ipcp);
 437                if (err)
 438                        goto out_unlock0;
 439
 440                msq->q_qbytes = msqid64.msg_qbytes;
 441
 442                msq->q_ctime = get_seconds();
 443                /* sleeping receivers might be excluded by
 444                 * stricter permissions.
 445                 */
 446                expunge_all(msq, -EAGAIN);
 447                /* sleeping senders might be able to send
 448                 * due to a larger queue size.
 449                 */
 450                ss_wakeup(&msq->q_senders, 0);
 451                break;
 452        default:
 453                err = -EINVAL;
 454                goto out_unlock1;
 455        }
 456
 457out_unlock0:
 458        ipc_unlock_object(&msq->q_perm);
 459out_unlock1:
 460        rcu_read_unlock();
 461out_up:
 462        up_write(&msg_ids(ns).rw_mutex);
 463        return err;
 464}
 465
 466static int msgctl_nolock(struct ipc_namespace *ns, int msqid,
 467                         int cmd, int version, void __user *buf)
 468{
 469        int err;
 470        struct msg_queue *msq;
 471
 472        switch (cmd) {
 473        case IPC_INFO:
 474        case MSG_INFO:
 475        {
 476                struct msginfo msginfo;
 477                int max_id;
 478
 479                if (!buf)
 480                        return -EFAULT;
 481
 482                /*
 483                 * We must not return kernel stack data.
 484                 * due to padding, it's not enough
 485                 * to set all member fields.
 486                 */
 487                err = security_msg_queue_msgctl(NULL, cmd);
 488                if (err)
 489                        return err;
 490
 491                memset(&msginfo, 0, sizeof(msginfo));
 492                msginfo.msgmni = ns->msg_ctlmni;
 493                msginfo.msgmax = ns->msg_ctlmax;
 494                msginfo.msgmnb = ns->msg_ctlmnb;
 495                msginfo.msgssz = MSGSSZ;
 496                msginfo.msgseg = MSGSEG;
 497                down_read(&msg_ids(ns).rw_mutex);
 498                if (cmd == MSG_INFO) {
 499                        msginfo.msgpool = msg_ids(ns).in_use;
 500                        msginfo.msgmap = atomic_read(&ns->msg_hdrs);
 501                        msginfo.msgtql = atomic_read(&ns->msg_bytes);
 502                } else {
 503                        msginfo.msgmap = MSGMAP;
 504                        msginfo.msgpool = MSGPOOL;
 505                        msginfo.msgtql = MSGTQL;
 506                }
 507                max_id = ipc_get_maxid(&msg_ids(ns));
 508                up_read(&msg_ids(ns).rw_mutex);
 509                if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
 510                        return -EFAULT;
 511                return (max_id < 0) ? 0 : max_id;
 512        }
 513
 514        case MSG_STAT:
 515        case IPC_STAT:
 516        {
 517                struct msqid64_ds tbuf;
 518                int success_return;
 519
 520                if (!buf)
 521                        return -EFAULT;
 522
 523                memset(&tbuf, 0, sizeof(tbuf));
 524
 525                rcu_read_lock();
 526                if (cmd == MSG_STAT) {
 527                        msq = msq_obtain_object(ns, msqid);
 528                        if (IS_ERR(msq)) {
 529                                err = PTR_ERR(msq);
 530                                goto out_unlock;
 531                        }
 532                        success_return = msq->q_perm.id;
 533                } else {
 534                        msq = msq_obtain_object_check(ns, msqid);
 535                        if (IS_ERR(msq)) {
 536                                err = PTR_ERR(msq);
 537                                goto out_unlock;
 538                        }
 539                        success_return = 0;
 540                }
 541
 542                err = -EACCES;
 543                if (ipcperms(ns, &msq->q_perm, S_IRUGO))
 544                        goto out_unlock;
 545
 546                err = security_msg_queue_msgctl(msq, cmd);
 547                if (err)
 548                        goto out_unlock;
 549
 550                kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm);
 551                tbuf.msg_stime  = msq->q_stime;
 552                tbuf.msg_rtime  = msq->q_rtime;
 553                tbuf.msg_ctime  = msq->q_ctime;
 554                tbuf.msg_cbytes = msq->q_cbytes;
 555                tbuf.msg_qnum   = msq->q_qnum;
 556                tbuf.msg_qbytes = msq->q_qbytes;
 557                tbuf.msg_lspid  = msq->q_lspid;
 558                tbuf.msg_lrpid  = msq->q_lrpid;
 559                rcu_read_unlock();
 560
 561                if (copy_msqid_to_user(buf, &tbuf, version))
 562                        return -EFAULT;
 563                return success_return;
 564        }
 565
 566        default:
 567                return -EINVAL;
 568        }
 569
 570        return err;
 571out_unlock:
 572        rcu_read_unlock();
 573        return err;
 574}
 575
 576SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
 577{
 578        int version;
 579        struct ipc_namespace *ns;
 580
 581        if (msqid < 0 || cmd < 0)
 582                return -EINVAL;
 583
 584        version = ipc_parse_version(&cmd);
 585        ns = current->nsproxy->ipc_ns;
 586
 587        switch (cmd) {
 588        case IPC_INFO:
 589        case MSG_INFO:
 590        case MSG_STAT:  /* msqid is an index rather than a msg queue id */
 591        case IPC_STAT:
 592                return msgctl_nolock(ns, msqid, cmd, version, buf);
 593        case IPC_SET:
 594        case IPC_RMID:
 595                return msgctl_down(ns, msqid, cmd, buf, version);
 596        default:
 597                return  -EINVAL;
 598        }
 599}
 600
 601static int testmsg(struct msg_msg *msg, long type, int mode)
 602{
 603        switch(mode)
 604        {
 605                case SEARCH_ANY:
 606                case SEARCH_NUMBER:
 607                        return 1;
 608                case SEARCH_LESSEQUAL:
 609                        if (msg->m_type <=type)
 610                                return 1;
 611                        break;
 612                case SEARCH_EQUAL:
 613                        if (msg->m_type == type)
 614                                return 1;
 615                        break;
 616                case SEARCH_NOTEQUAL:
 617                        if (msg->m_type != type)
 618                                return 1;
 619                        break;
 620        }
 621        return 0;
 622}
 623
 624static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg)
 625{
 626        struct msg_receiver *msr, *t;
 627
 628        list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
 629                if (testmsg(msg, msr->r_msgtype, msr->r_mode) &&
 630                    !security_msg_queue_msgrcv(msq, msg, msr->r_tsk,
 631                                               msr->r_msgtype, msr->r_mode)) {
 632
 633                        list_del(&msr->r_list);
 634                        if (msr->r_maxsize < msg->m_ts) {
 635                                msr->r_msg = NULL;
 636                                wake_up_process(msr->r_tsk);
 637                                smp_mb();
 638                                msr->r_msg = ERR_PTR(-E2BIG);
 639                        } else {
 640                                msr->r_msg = NULL;
 641                                msq->q_lrpid = task_pid_vnr(msr->r_tsk);
 642                                msq->q_rtime = get_seconds();
 643                                wake_up_process(msr->r_tsk);
 644                                smp_mb();
 645                                msr->r_msg = msg;
 646
 647                                return 1;
 648                        }
 649                }
 650        }
 651        return 0;
 652}
 653
 654long do_msgsnd(int msqid, long mtype, void __user *mtext,
 655                size_t msgsz, int msgflg)
 656{
 657        struct msg_queue *msq;
 658        struct msg_msg *msg;
 659        int err;
 660        struct ipc_namespace *ns;
 661
 662        ns = current->nsproxy->ipc_ns;
 663
 664        if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0)
 665                return -EINVAL;
 666        if (mtype < 1)
 667                return -EINVAL;
 668
 669        msg = load_msg(mtext, msgsz);
 670        if (IS_ERR(msg))
 671                return PTR_ERR(msg);
 672
 673        msg->m_type = mtype;
 674        msg->m_ts = msgsz;
 675
 676        rcu_read_lock();
 677        msq = msq_obtain_object_check(ns, msqid);
 678        if (IS_ERR(msq)) {
 679                err = PTR_ERR(msq);
 680                goto out_unlock1;
 681        }
 682
 683        for (;;) {
 684                struct msg_sender s;
 685
 686                err = -EACCES;
 687                if (ipcperms(ns, &msq->q_perm, S_IWUGO))
 688                        goto out_unlock1;
 689
 690                err = security_msg_queue_msgsnd(msq, msg, msgflg);
 691                if (err)
 692                        goto out_unlock1;
 693
 694                if (msgsz + msq->q_cbytes <= msq->q_qbytes &&
 695                                1 + msq->q_qnum <= msq->q_qbytes) {
 696                        break;
 697                }
 698
 699                /* queue full, wait: */
 700                if (msgflg & IPC_NOWAIT) {
 701                        err = -EAGAIN;
 702                        goto out_unlock1;
 703                }
 704
 705                ipc_lock_object(&msq->q_perm);
 706                ss_add(msq, &s);
 707
 708                if (!ipc_rcu_getref(msq)) {
 709                        err = -EIDRM;
 710                        goto out_unlock0;
 711                }
 712
 713                ipc_unlock_object(&msq->q_perm);
 714                rcu_read_unlock();
 715                schedule();
 716
 717                rcu_read_lock();
 718                ipc_lock_object(&msq->q_perm);
 719
 720                ipc_rcu_putref(msq);
 721                if (msq->q_perm.deleted) {
 722                        err = -EIDRM;
 723                        goto out_unlock0;
 724                }
 725
 726                ss_del(&s);
 727
 728                if (signal_pending(current)) {
 729                        err = -ERESTARTNOHAND;
 730                        goto out_unlock0;
 731                }
 732
 733                ipc_unlock_object(&msq->q_perm);
 734        }
 735
 736        ipc_lock_object(&msq->q_perm);
 737        msq->q_lspid = task_tgid_vnr(current);
 738        msq->q_stime = get_seconds();
 739
 740        if (!pipelined_send(msq, msg)) {
 741                /* no one is waiting for this message, enqueue it */
 742                list_add_tail(&msg->m_list, &msq->q_messages);
 743                msq->q_cbytes += msgsz;
 744                msq->q_qnum++;
 745                atomic_add(msgsz, &ns->msg_bytes);
 746                atomic_inc(&ns->msg_hdrs);
 747        }
 748
 749        err = 0;
 750        msg = NULL;
 751
 752out_unlock0:
 753        ipc_unlock_object(&msq->q_perm);
 754out_unlock1:
 755        rcu_read_unlock();
 756        if (msg != NULL)
 757                free_msg(msg);
 758        return err;
 759}
 760
 761SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
 762                int, msgflg)
 763{
 764        long mtype;
 765
 766        if (get_user(mtype, &msgp->mtype))
 767                return -EFAULT;
 768        return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg);
 769}
 770
 771static inline int convert_mode(long *msgtyp, int msgflg)
 772{
 773        if (msgflg & MSG_COPY)
 774                return SEARCH_NUMBER;
 775        /*
 776         *  find message of correct type.
 777         *  msgtyp = 0 => get first.
 778         *  msgtyp > 0 => get first message of matching type.
 779         *  msgtyp < 0 => get message with least type must be < abs(msgtype).
 780         */
 781        if (*msgtyp == 0)
 782                return SEARCH_ANY;
 783        if (*msgtyp < 0) {
 784                *msgtyp = -*msgtyp;
 785                return SEARCH_LESSEQUAL;
 786        }
 787        if (msgflg & MSG_EXCEPT)
 788                return SEARCH_NOTEQUAL;
 789        return SEARCH_EQUAL;
 790}
 791
 792static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
 793{
 794        struct msgbuf __user *msgp = dest;
 795        size_t msgsz;
 796
 797        if (put_user(msg->m_type, &msgp->mtype))
 798                return -EFAULT;
 799
 800        msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
 801        if (store_msg(msgp->mtext, msg, msgsz))
 802                return -EFAULT;
 803        return msgsz;
 804}
 805
 806#ifdef CONFIG_CHECKPOINT_RESTORE
 807/*
 808 * This function creates new kernel message structure, large enough to store
 809 * bufsz message bytes.
 810 */
 811static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
 812{
 813        struct msg_msg *copy;
 814
 815        /*
 816         * Create dummy message to copy real message to.
 817         */
 818        copy = load_msg(buf, bufsz);
 819        if (!IS_ERR(copy))
 820                copy->m_ts = bufsz;
 821        return copy;
 822}
 823
 824static inline void free_copy(struct msg_msg *copy)
 825{
 826        if (copy)
 827                free_msg(copy);
 828}
 829#else
 830static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
 831{
 832        return ERR_PTR(-ENOSYS);
 833}
 834
 835static inline void free_copy(struct msg_msg *copy)
 836{
 837}
 838#endif
 839
 840static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode)
 841{
 842        struct msg_msg *msg, *found = NULL;
 843        long count = 0;
 844
 845        list_for_each_entry(msg, &msq->q_messages, m_list) {
 846                if (testmsg(msg, *msgtyp, mode) &&
 847                    !security_msg_queue_msgrcv(msq, msg, current,
 848                                               *msgtyp, mode)) {
 849                        if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) {
 850                                *msgtyp = msg->m_type - 1;
 851                                found = msg;
 852                        } else if (mode == SEARCH_NUMBER) {
 853                                if (*msgtyp == count)
 854                                        return msg;
 855                        } else
 856                                return msg;
 857                        count++;
 858                }
 859        }
 860
 861        return found ?: ERR_PTR(-EAGAIN);
 862}
 863
 864long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg,
 865               long (*msg_handler)(void __user *, struct msg_msg *, size_t))
 866{
 867        int mode;
 868        struct msg_queue *msq;
 869        struct ipc_namespace *ns;
 870        struct msg_msg *msg, *copy = NULL;
 871
 872        ns = current->nsproxy->ipc_ns;
 873
 874        if (msqid < 0 || (long) bufsz < 0)
 875                return -EINVAL;
 876
 877        if (msgflg & MSG_COPY) {
 878                copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax));
 879                if (IS_ERR(copy))
 880                        return PTR_ERR(copy);
 881        }
 882        mode = convert_mode(&msgtyp, msgflg);
 883
 884        rcu_read_lock();
 885        msq = msq_obtain_object_check(ns, msqid);
 886        if (IS_ERR(msq)) {
 887                rcu_read_unlock();
 888                free_copy(copy);
 889                return PTR_ERR(msq);
 890        }
 891
 892        for (;;) {
 893                struct msg_receiver msr_d;
 894
 895                msg = ERR_PTR(-EACCES);
 896                if (ipcperms(ns, &msq->q_perm, S_IRUGO))
 897                        goto out_unlock1;
 898
 899                ipc_lock_object(&msq->q_perm);
 900                msg = find_msg(msq, &msgtyp, mode);
 901                if (!IS_ERR(msg)) {
 902                        /*
 903                         * Found a suitable message.
 904                         * Unlink it from the queue.
 905                         */
 906                        if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
 907                                msg = ERR_PTR(-E2BIG);
 908                                goto out_unlock0;
 909                        }
 910                        /*
 911                         * If we are copying, then do not unlink message and do
 912                         * not update queue parameters.
 913                         */
 914                        if (msgflg & MSG_COPY) {
 915                                msg = copy_msg(msg, copy);
 916                                goto out_unlock0;
 917                        }
 918
 919                        list_del(&msg->m_list);
 920                        msq->q_qnum--;
 921                        msq->q_rtime = get_seconds();
 922                        msq->q_lrpid = task_tgid_vnr(current);
 923                        msq->q_cbytes -= msg->m_ts;
 924                        atomic_sub(msg->m_ts, &ns->msg_bytes);
 925                        atomic_dec(&ns->msg_hdrs);
 926                        ss_wakeup(&msq->q_senders, 0);
 927
 928                        goto out_unlock0;
 929                }
 930
 931                /* No message waiting. Wait for a message */
 932                if (msgflg & IPC_NOWAIT) {
 933                        msg = ERR_PTR(-ENOMSG);
 934                        goto out_unlock0;
 935                }
 936
 937                list_add_tail(&msr_d.r_list, &msq->q_receivers);
 938                msr_d.r_tsk = current;
 939                msr_d.r_msgtype = msgtyp;
 940                msr_d.r_mode = mode;
 941                if (msgflg & MSG_NOERROR)
 942                        msr_d.r_maxsize = INT_MAX;
 943                else
 944                        msr_d.r_maxsize = bufsz;
 945                msr_d.r_msg = ERR_PTR(-EAGAIN);
 946                current->state = TASK_INTERRUPTIBLE;
 947
 948                ipc_unlock_object(&msq->q_perm);
 949                rcu_read_unlock();
 950                schedule();
 951
 952                /* Lockless receive, part 1:
 953                 * Disable preemption.  We don't hold a reference to the queue
 954                 * and getting a reference would defeat the idea of a lockless
 955                 * operation, thus the code relies on rcu to guarantee the
 956                 * existence of msq:
 957                 * Prior to destruction, expunge_all(-EIRDM) changes r_msg.
 958                 * Thus if r_msg is -EAGAIN, then the queue not yet destroyed.
 959                 * rcu_read_lock() prevents preemption between reading r_msg
 960                 * and acquiring the q_perm.lock in ipc_lock_object().
 961                 */
 962                rcu_read_lock();
 963
 964                /* Lockless receive, part 2:
 965                 * Wait until pipelined_send or expunge_all are outside of
 966                 * wake_up_process(). There is a race with exit(), see
 967                 * ipc/mqueue.c for the details.
 968                 */
 969                msg = (struct msg_msg*)msr_d.r_msg;
 970                while (msg == NULL) {
 971                        cpu_relax();
 972                        msg = (struct msg_msg *)msr_d.r_msg;
 973                }
 974
 975                /* Lockless receive, part 3:
 976                 * If there is a message or an error then accept it without
 977                 * locking.
 978                 */
 979                if (msg != ERR_PTR(-EAGAIN))
 980                        goto out_unlock1;
 981
 982                /* Lockless receive, part 3:
 983                 * Acquire the queue spinlock.
 984                 */
 985                ipc_lock_object(&msq->q_perm);
 986
 987                /* Lockless receive, part 4:
 988                 * Repeat test after acquiring the spinlock.
 989                 */
 990                msg = (struct msg_msg*)msr_d.r_msg;
 991                if (msg != ERR_PTR(-EAGAIN))
 992                        goto out_unlock0;
 993
 994                list_del(&msr_d.r_list);
 995                if (signal_pending(current)) {
 996                        msg = ERR_PTR(-ERESTARTNOHAND);
 997                        goto out_unlock0;
 998                }
 999
1000                ipc_unlock_object(&msq->q_perm);
1001        }
1002
1003out_unlock0:
1004        ipc_unlock_object(&msq->q_perm);
1005out_unlock1:
1006        rcu_read_unlock();
1007        if (IS_ERR(msg)) {
1008                free_copy(copy);
1009                return PTR_ERR(msg);
1010        }
1011
1012        bufsz = msg_handler(buf, msg, bufsz);
1013        free_msg(msg);
1014
1015        return bufsz;
1016}
1017
1018SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
1019                long, msgtyp, int, msgflg)
1020{
1021        return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill);
1022}
1023
1024#ifdef CONFIG_PROC_FS
1025static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
1026{
1027        struct user_namespace *user_ns = seq_user_ns(s);
1028        struct msg_queue *msq = it;
1029
1030        return seq_printf(s,
1031                        "%10d %10d  %4o  %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu\n",
1032                        msq->q_perm.key,
1033                        msq->q_perm.id,
1034                        msq->q_perm.mode,
1035                        msq->q_cbytes,
1036                        msq->q_qnum,
1037                        msq->q_lspid,
1038                        msq->q_lrpid,
1039                        from_kuid_munged(user_ns, msq->q_perm.uid),
1040                        from_kgid_munged(user_ns, msq->q_perm.gid),
1041                        from_kuid_munged(user_ns, msq->q_perm.cuid),
1042                        from_kgid_munged(user_ns, msq->q_perm.cgid),
1043                        msq->q_stime,
1044                        msq->q_rtime,
1045                        msq->q_ctime);
1046}
1047#endif
1048
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