ipc/msg.c

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