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 static void msg_rcu_free(struct rcu_head *head)
 169 {
 170         struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu);
 171         struct msg_queue *msq = ipc_rcu_to_struct(p);
 172
 173         security_msg_queue_free(msq);
 174         ipc_rcu_free(head);
 175 }
 176
 177 /**
 178  * newque - Create a new msg queue
 179  * @ns: namespace
 180  * @params: ptr to the structure that contains the key and msgflg
 181  *
 182  * Called with msg_ids.rwsem held (writer)
 183  */
 184 static int newque(struct ipc_namespace *ns, struct ipc_params *params)
 185 {
 186         struct msg_queue *msq;
 187         int id, retval;
 188         key_t key = params->key;
 189         int msgflg = params->flg;
 190
 191         msq = ipc_rcu_alloc(sizeof(*msq));
 192         if (!msq)
 193                 return -ENOMEM;
 194
 195         msq->q_perm.mode = msgflg & S_IRWXUGO;
 196         msq->q_perm.key = key;
 197
 198         msq->q_perm.security = NULL;
 199         retval = security_msg_queue_alloc(msq);
 200         if (retval) {
 201                 ipc_rcu_putref(msq, ipc_rcu_free);
 202                 return retval;
 203         }
 204
 205         /* ipc_addid() locks msq upon success. */
 206         id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
 207         if (id < 0) {
 208                 ipc_rcu_putref(msq, msg_rcu_free);
 209                 return id;
 210         }
 211
 212         msq->q_stime = msq->q_rtime = 0;
 213         msq->q_ctime = get_seconds();
 214         msq->q_cbytes = msq->q_qnum = 0;
 215         msq->q_qbytes = ns->msg_ctlmnb;
 216         msq->q_lspid = msq->q_lrpid = 0;
 217         INIT_LIST_HEAD(&msq->q_messages);
 218         INIT_LIST_HEAD(&msq->q_receivers);
 219         INIT_LIST_HEAD(&msq->q_senders);
 220
 221         ipc_unlock_object(&msq->q_perm);
 222         rcu_read_unlock();
 223
 224         return msq->q_perm.id;
 225 }
 226
 227 static inline void ss_add(struct msg_queue *msq, struct msg_sender *mss)
 228 {
 229         mss->tsk = current;
 230         current->state = TASK_INTERRUPTIBLE;
 231         list_add_tail(&mss->list, &msq->q_senders);
 232 }
 233
 234 static inline void ss_del(struct msg_sender *mss)
 235 {
 236         if (mss->list.next != NULL)
 237                 list_del(&mss->list);
 238 }
 239
 240 static void ss_wakeup(struct list_head *h, int kill)
 241 {
 242         struct msg_sender *mss, *t;
 243
 244         list_for_each_entry_safe(mss, t, h, list) {
 245                 if (kill)
 246                         mss->list.next = NULL;
 247                 wake_up_process(mss->tsk);
 248         }
 249 }
 250
 251 static void expunge_all(struct msg_queue *msq, int res)
 252 {
 253         struct msg_receiver *msr, *t;
 254
 255         list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
 256                 msr->r_msg = NULL;
 257                 wake_up_process(msr->r_tsk);
 258                 smp_mb();
 259                 msr->r_msg = ERR_PTR(res);
 260         }
 261 }
 262
 263 /*
 264  * freeque() wakes up waiters on the sender and receiver waiting queue,
 265  * removes the message queue from message queue ID IDR, and cleans up all the
 266  * messages associated with this queue.
 267  *
 268  * msg_ids.rwsem (writer) and the spinlock for this message queue are held
 269  * before freeque() is called. msg_ids.rwsem remains locked on exit.
 270  */
 271 static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
 272 {
 273         struct msg_msg *msg, *t;
 274         struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
 275
 276         expunge_all(msq, -EIDRM);
 277         ss_wakeup(&msq->q_senders, 1);
 278         msg_rmid(ns, msq);
 279         ipc_unlock_object(&msq->q_perm);
 280         rcu_read_unlock();
 281
 282         list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) {
 283                 atomic_dec(&ns->msg_hdrs);
 284                 free_msg(msg);
 285         }
 286         atomic_sub(msq->q_cbytes, &ns->msg_bytes);
 287         ipc_rcu_putref(msq, msg_rcu_free);
 288 }
 289
 290 /*
 291  * Called with msg_ids.rwsem and ipcp locked.
 292  */
 293 static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg)
 294 {
 295         struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
 296
 297         return security_msg_queue_associate(msq, msgflg);
 298 }
 299
 300 SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
 301 {
 302         struct ipc_namespace *ns;
 303         struct ipc_ops msg_ops;
 304         struct ipc_params msg_params;
 305
 306         ns = current->nsproxy->ipc_ns;
 307
 308         msg_ops.getnew = newque;
 309         msg_ops.associate = msg_security;
 310         msg_ops.more_checks = NULL;
 311
 312         msg_params.key = key;
 313         msg_params.flg = msgflg;
 314
 315         return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params);
 316 }
 317
 318 static inline unsigned long
 319 copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
 320 {
 321         switch(version) {
 322         case IPC_64:
 323                 return copy_to_user(buf, in, sizeof(*in));
 324         case IPC_OLD:
 325         {
 326                 struct msqid_ds out;
 327
 328                 memset(&out, 0, sizeof(out));
 329
 330                 ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
 331
 332                 out.msg_stime           = in->msg_stime;
 333                 out.msg_rtime           = in->msg_rtime;
 334                 out.msg_ctime           = in->msg_ctime;
 335
 336                 if (in->msg_cbytes > USHRT_MAX)
 337                         out.msg_cbytes  = USHRT_MAX;
 338                 else
 339                         out.msg_cbytes  = in->msg_cbytes;
 340                 out.msg_lcbytes         = in->msg_cbytes;
 341
 342                 if (in->msg_qnum > USHRT_MAX)
 343                         out.msg_qnum    = USHRT_MAX;
 344                 else
 345                         out.msg_qnum    = in->msg_qnum;
 346
 347                 if (in->msg_qbytes > USHRT_MAX)
 348                         out.msg_qbytes  = USHRT_MAX;
 349                 else
 350                         out.msg_qbytes  = in->msg_qbytes;
 351                 out.msg_lqbytes         = in->msg_qbytes;
 352
 353                 out.msg_lspid           = in->msg_lspid;
 354                 out.msg_lrpid           = in->msg_lrpid;
 355
 356                 return copy_to_user(buf, &out, sizeof(out));
 357         }
 358         default:
 359                 return -EINVAL;
 360         }
 361 }
 362
 363 static inline unsigned long
 364 copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version)
 365 {
 366         switch(version) {
 367         case IPC_64:
 368                 if (copy_from_user(out, buf, sizeof(*out)))
 369                         return -EFAULT;
 370                 return 0;
 371         case IPC_OLD:
 372         {
 373                 struct msqid_ds tbuf_old;
 374
 375                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 376                         return -EFAULT;
 377
 378                 out->msg_perm.uid       = tbuf_old.msg_perm.uid;
 379                 out->msg_perm.gid       = tbuf_old.msg_perm.gid;
 380                 out->msg_perm.mode      = tbuf_old.msg_perm.mode;
 381
 382                 if (tbuf_old.msg_qbytes == 0)
 383                         out->msg_qbytes = tbuf_old.msg_lqbytes;
 384                 else
 385                         out->msg_qbytes = tbuf_old.msg_qbytes;
 386
 387                 return 0;
 388         }
 389         default:
 390                 return -EINVAL;
 391         }
 392 }
 393
 394 /*
 395  * This function handles some msgctl commands which require the rwsem
 396  * to be held in write mode.
 397  * NOTE: no locks must be held, the rwsem is taken inside this function.
 398  */
 399 static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
 400                        struct msqid_ds __user *buf, int version)
 401 {
 402         struct kern_ipc_perm *ipcp;
 403         struct msqid64_ds uninitialized_var(msqid64);
 404         struct msg_queue *msq;
 405         int err;
 406
 407         if (cmd == IPC_SET) {
 408                 if (copy_msqid_from_user(&msqid64, buf, version))
 409                         return -EFAULT;
 410         }
 411
 412         down_write(&msg_ids(ns).rwsem);
 413         rcu_read_lock();
 414
 415         ipcp = ipcctl_pre_down_nolock(ns, &msg_ids(ns), msqid, cmd,
 416                                       &msqid64.msg_perm, msqid64.msg_qbytes);
 417         if (IS_ERR(ipcp)) {
 418                 err = PTR_ERR(ipcp);
 419                 goto out_unlock1;
 420         }
 421
 422         msq = container_of(ipcp, struct msg_queue, q_perm);
 423
 424         err = security_msg_queue_msgctl(msq, cmd);
 425         if (err)
 426                 goto out_unlock1;
 427
 428         switch (cmd) {
 429         case IPC_RMID:
 430                 ipc_lock_object(&msq->q_perm);
 431                 /* freeque unlocks the ipc object and rcu */
 432                 freeque(ns, ipcp);
 433                 goto out_up;
 434         case IPC_SET:
 435                 if (msqid64.msg_qbytes > ns->msg_ctlmnb &&
 436                     !capable(CAP_SYS_RESOURCE)) {
 437                         err = -EPERM;
 438                         goto out_unlock1;
 439                 }
 440
 441                 ipc_lock_object(&msq->q_perm);
 442                 err = ipc_update_perm(&msqid64.msg_perm, ipcp);
 443                 if (err)
 444                         goto out_unlock0;
 445
 446                 msq->q_qbytes = msqid64.msg_qbytes;
 447
 448                 msq->q_ctime = get_seconds();
 449                 /* sleeping receivers might be excluded by
 450                  * stricter permissions.
 451                  */
 452                 expunge_all(msq, -EAGAIN);
 453                 /* sleeping senders might be able to send
 454                  * due to a larger queue size.
 455                  */
 456                 ss_wakeup(&msq->q_senders, 0);
 457                 break;
 458         default:
 459                 err = -EINVAL;
 460                 goto out_unlock1;
 461         }
 462
 463 out_unlock0:
 464         ipc_unlock_object(&msq->q_perm);
 465 out_unlock1:
 466         rcu_read_unlock();
 467 out_up:
 468         up_write(&msg_ids(ns).rwsem);
 469         return err;
 470 }
 471
 472 static int msgctl_nolock(struct ipc_namespace *ns, int msqid,
 473                          int cmd, int version, void __user *buf)
 474 {
 475         int err;
 476         struct msg_queue *msq;
 477
 478         switch (cmd) {
 479         case IPC_INFO:
 480         case MSG_INFO:
 481         {
 482                 struct msginfo msginfo;
 483                 int max_id;
 484
 485                 if (!buf)
 486                         return -EFAULT;
 487
 488                 /*
 489                  * We must not return kernel stack data.
 490                  * due to padding, it's not enough
 491                  * to set all member fields.
 492                  */
 493                 err = security_msg_queue_msgctl(NULL, cmd);
 494                 if (err)
 495                         return err;
 496
 497                 memset(&msginfo, 0, sizeof(msginfo));
 498                 msginfo.msgmni = ns->msg_ctlmni;
 499                 msginfo.msgmax = ns->msg_ctlmax;
 500                 msginfo.msgmnb = ns->msg_ctlmnb;
 501                 msginfo.msgssz = MSGSSZ;
 502                 msginfo.msgseg = MSGSEG;
 503                 down_read(&msg_ids(ns).rwsem);
 504                 if (cmd == MSG_INFO) {
 505                         msginfo.msgpool = msg_ids(ns).in_use;
 506                         msginfo.msgmap = atomic_read(&ns->msg_hdrs);
 507                         msginfo.msgtql = atomic_read(&ns->msg_bytes);
 508                 } else {
 509                         msginfo.msgmap = MSGMAP;
 510                         msginfo.msgpool = MSGPOOL;
 511                         msginfo.msgtql = MSGTQL;
 512                 }
 513                 max_id = ipc_get_maxid(&msg_ids(ns));
 514                 up_read(&msg_ids(ns).rwsem);
 515                 if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
 516                         return -EFAULT;
 517                 return (max_id < 0) ? 0 : max_id;
 518         }
 519
 520         case MSG_STAT:
 521         case IPC_STAT:
 522         {
 523                 struct msqid64_ds tbuf;
 524                 int success_return;
 525
 526                 if (!buf)
 527                         return -EFAULT;
 528
 529                 memset(&tbuf, 0, sizeof(tbuf));
 530
 531                 rcu_read_lock();
 532                 if (cmd == MSG_STAT) {
 533                         msq = msq_obtain_object(ns, msqid);
 534                         if (IS_ERR(msq)) {
 535                                 err = PTR_ERR(msq);
 536                                 goto out_unlock;
 537                         }
 538                         success_return = msq->q_perm.id;
 539                 } else {
 540                         msq = msq_obtain_object_check(ns, msqid);
 541                         if (IS_ERR(msq)) {
 542                                 err = PTR_ERR(msq);
 543                                 goto out_unlock;
 544                         }
 545                         success_return = 0;
 546                 }
 547
 548                 err = -EACCES;
 549                 if (ipcperms(ns, &msq->q_perm, S_IRUGO))
 550                         goto out_unlock;
 551
 552                 err = security_msg_queue_msgctl(msq, cmd);
 553                 if (err)
 554                         goto out_unlock;
 555
 556                 kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm);
 557                 tbuf.msg_stime  = msq->q_stime;
 558                 tbuf.msg_rtime  = msq->q_rtime;
 559                 tbuf.msg_ctime  = msq->q_ctime;
 560                 tbuf.msg_cbytes = msq->q_cbytes;
 561                 tbuf.msg_qnum   = msq->q_qnum;
 562                 tbuf.msg_qbytes = msq->q_qbytes;
 563                 tbuf.msg_lspid  = msq->q_lspid;
 564                 tbuf.msg_lrpid  = msq->q_lrpid;
 565                 rcu_read_unlock();
 566
 567                 if (copy_msqid_to_user(buf, &tbuf, version))
 568                         return -EFAULT;
 569                 return success_return;
 570         }
 571
 572         default:
 573                 return -EINVAL;
 574         }
 575
 576         return err;
 577 out_unlock:
 578         rcu_read_unlock();
 579         return err;
 580 }
 581
 582 SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
 583 {
 584         int version;
 585         struct ipc_namespace *ns;
 586
 587         if (msqid < 0 || cmd < 0)
 588                 return -EINVAL;
 589
 590         version = ipc_parse_version(&cmd);
 591         ns = current->nsproxy->ipc_ns;
 592
 593         switch (cmd) {
 594         case IPC_INFO:
 595         case MSG_INFO:
 596         case MSG_STAT:  /* msqid is an index rather than a msg queue id */
 597         case IPC_STAT:
 598                 return msgctl_nolock(ns, msqid, cmd, version, buf);
 599         case IPC_SET:
 600         case IPC_RMID:
 601                 return msgctl_down(ns, msqid, cmd, buf, version);
 602         default:
 603                 return  -EINVAL;
 604         }
 605 }
 606
 607 static int testmsg(struct msg_msg *msg, long type, int mode)
 608 {
 609         switch(mode)
 610         {
 611                 case SEARCH_ANY:
 612                 case SEARCH_NUMBER:
 613                         return 1;
 614                 case SEARCH_LESSEQUAL:
 615                         if (msg->m_type <=type)
 616                                 return 1;
 617                         break;
 618                 case SEARCH_EQUAL:
 619                         if (msg->m_type == type)
 620                                 return 1;
 621                         break;
 622                 case SEARCH_NOTEQUAL:
 623                         if (msg->m_type != type)
 624                                 return 1;
 625                         break;
 626         }
 627         return 0;
 628 }
 629
 630 static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg)
 631 {
 632         struct msg_receiver *msr, *t;
 633
 634         list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
 635                 if (testmsg(msg, msr->r_msgtype, msr->r_mode) &&
 636                     !security_msg_queue_msgrcv(msq, msg, msr->r_tsk,
 637                                                msr->r_msgtype, msr->r_mode)) {
 638
 639                         list_del(&msr->r_list);
 640                         if (msr->r_maxsize < msg->m_ts) {
 641                                 msr->r_msg = NULL;
 642                                 wake_up_process(msr->r_tsk);
 643                                 smp_mb();
 644                                 msr->r_msg = ERR_PTR(-E2BIG);
 645                         } else {
 646                                 msr->r_msg = NULL;
 647                                 msq->q_lrpid = task_pid_vnr(msr->r_tsk);
 648                                 msq->q_rtime = get_seconds();
 649                                 wake_up_process(msr->r_tsk);
 650                                 smp_mb();
 651                                 msr->r_msg = msg;
 652
 653                                 return 1;
 654                         }
 655                 }
 656         }
 657         return 0;
 658 }
 659
 660 long do_msgsnd(int msqid, long mtype, void __user *mtext,
 661                 size_t msgsz, int msgflg)
 662 {
 663         struct msg_queue *msq;
 664         struct msg_msg *msg;
 665         int err;
 666         struct ipc_namespace *ns;
 667
 668         ns = current->nsproxy->ipc_ns;
 669
 670         if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0)
 671                 return -EINVAL;
 672         if (mtype < 1)
 673                 return -EINVAL;
 674
 675         msg = load_msg(mtext, msgsz);
 676         if (IS_ERR(msg))
 677                 return PTR_ERR(msg);
 678
 679         msg->m_type = mtype;
 680         msg->m_ts = msgsz;
 681
 682         rcu_read_lock();
 683         msq = msq_obtain_object_check(ns, msqid);
 684         if (IS_ERR(msq)) {
 685                 err = PTR_ERR(msq);
 686                 goto out_unlock1;
 687         }
 688
 689         ipc_lock_object(&msq->q_perm);
 690
 691         for (;;) {
 692                 struct msg_sender s;
 693
 694                 err = -EACCES;
 695                 if (ipcperms(ns, &msq->q_perm, S_IWUGO))
 696                         goto out_unlock0;
 697
 698                 /* raced with RMID? */
 699                 if (msq->q_perm.deleted) {
 700                         err = -EIDRM;
 701                         goto out_unlock0;
 702                 }
 703
 704                 err = security_msg_queue_msgsnd(msq, msg, msgflg);
 705                 if (err)
 706                         goto out_unlock0;
 707
 708                 if (msgsz + msq->q_cbytes <= msq->q_qbytes &&
 709                                 1 + msq->q_qnum <= msq->q_qbytes) {
 710                         break;
 711                 }
 712
 713                 /* queue full, wait: */
 714                 if (msgflg & IPC_NOWAIT) {
 715                         err = -EAGAIN;
 716                         goto out_unlock0;
 717                 }
 718
 719                 ss_add(msq, &s);
 720
 721                 if (!ipc_rcu_getref(msq)) {
 722                         err = -EIDRM;
 723                         goto out_unlock0;
 724                 }
 725
 726                 ipc_unlock_object(&msq->q_perm);
 727                 rcu_read_unlock();
 728                 schedule();
 729
 730                 rcu_read_lock();
 731                 ipc_lock_object(&msq->q_perm);
 732
 733                 ipc_rcu_putref(msq, ipc_rcu_free);
 734                 if (msq->q_perm.deleted) {
 735                         err = -EIDRM;
 736                         goto out_unlock0;
 737                 }
 738
 739                 ss_del(&s);
 740
 741                 if (signal_pending(current)) {
 742                         err = -ERESTARTNOHAND;
 743                         goto out_unlock0;
 744                 }
 745
 746         }
 747         msq->q_lspid = task_tgid_vnr(current);
 748         msq->q_stime = get_seconds();
 749
 750         if (!pipelined_send(msq, msg)) {
 751                 /* no one is waiting for this message, enqueue it */
 752                 list_add_tail(&msg->m_list, &msq->q_messages);
 753                 msq->q_cbytes += msgsz;
 754                 msq->q_qnum++;
 755                 atomic_add(msgsz, &ns->msg_bytes);
 756                 atomic_inc(&ns->msg_hdrs);
 757         }
 758
 759         err = 0;
 760         msg = NULL;
 761
 762 out_unlock0:
 763         ipc_unlock_object(&msq->q_perm);
 764 out_unlock1:
 765         rcu_read_unlock();
 766         if (msg != NULL)
 767                 free_msg(msg);
 768         return err;
 769 }
 770
 771 SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
 772                 int, msgflg)
 773 {
 774         long mtype;
 775
 776         if (get_user(mtype, &msgp->mtype))
 777                 return -EFAULT;
 778         return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg);
 779 }
 780
 781 static inline int convert_mode(long *msgtyp, int msgflg)
 782 {
 783         if (msgflg & MSG_COPY)
 784                 return SEARCH_NUMBER;
 785         /*
 786          *  find message of correct type.
 787          *  msgtyp = 0 => get first.
 788          *  msgtyp > 0 => get first message of matching type.
 789          *  msgtyp < 0 => get message with least type must be < abs(msgtype).
 790          */
 791         if (*msgtyp == 0)
 792                 return SEARCH_ANY;
 793         if (*msgtyp < 0) {
 794                 *msgtyp = -*msgtyp;
 795                 return SEARCH_LESSEQUAL;
 796         }
 797         if (msgflg & MSG_EXCEPT)
 798                 return SEARCH_NOTEQUAL;
 799         return SEARCH_EQUAL;
 800 }
 801
 802 static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
 803 {
 804         struct msgbuf __user *msgp = dest;
 805         size_t msgsz;
 806
 807         if (put_user(msg->m_type, &msgp->mtype))
 808                 return -EFAULT;
 809
 810         msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
 811         if (store_msg(msgp->mtext, msg, msgsz))
 812                 return -EFAULT;
 813         return msgsz;
 814 }
 815
 816 #ifdef CONFIG_CHECKPOINT_RESTORE
 817 /*
 818  * This function creates new kernel message structure, large enough to store
 819  * bufsz message bytes.
 820  */
 821 static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
 822 {
 823         struct msg_msg *copy;
 824
 825         /*
 826          * Create dummy message to copy real message to.
 827          */
 828         copy = load_msg(buf, bufsz);
 829         if (!IS_ERR(copy))
 830                 copy->m_ts = bufsz;
 831         return copy;
 832 }
 833
 834 static inline void free_copy(struct msg_msg *copy)
 835 {
 836         if (copy)
 837                 free_msg(copy);
 838 }
 839 #else
 840 static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
 841 {
 842         return ERR_PTR(-ENOSYS);
 843 }
 844
 845 static inline void free_copy(struct msg_msg *copy)
 846 {
 847 }
 848 #endif
 849
 850 static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode)
 851 {
 852         struct msg_msg *msg, *found = NULL;
 853         long count = 0;
 854
 855         list_for_each_entry(msg, &msq->q_messages, m_list) {
 856                 if (testmsg(msg, *msgtyp, mode) &&
 857                     !security_msg_queue_msgrcv(msq, msg, current,
 858                                                *msgtyp, mode)) {
 859                         if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) {
 860                                 *msgtyp = msg->m_type - 1;
 861                                 found = msg;
 862                         } else if (mode == SEARCH_NUMBER) {
 863                                 if (*msgtyp == count)
 864                                         return msg;
 865                         } else
 866                                 return msg;
 867                         count++;
 868                 }
 869         }
 870
 871         return found ?: ERR_PTR(-EAGAIN);
 872 }
 873
 874 long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg,
 875                long (*msg_handler)(void __user *, struct msg_msg *, size_t))
 876 {
 877         int mode;
 878         struct msg_queue *msq;
 879         struct ipc_namespace *ns;
 880         struct msg_msg *msg, *copy = NULL;
 881
 882         ns = current->nsproxy->ipc_ns;
 883
 884         if (msqid < 0 || (long) bufsz < 0)
 885                 return -EINVAL;
 886
 887         if (msgflg & MSG_COPY) {
 888                 copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax));
 889                 if (IS_ERR(copy))
 890                         return PTR_ERR(copy);
 891         }
 892         mode = convert_mode(&msgtyp, msgflg);
 893
 894         rcu_read_lock();
 895         msq = msq_obtain_object_check(ns, msqid);
 896         if (IS_ERR(msq)) {
 897                 rcu_read_unlock();
 898                 free_copy(copy);
 899                 return PTR_ERR(msq);
 900         }
 901
 902         for (;;) {
 903                 struct msg_receiver msr_d;
 904
 905                 msg = ERR_PTR(-EACCES);
 906                 if (ipcperms(ns, &msq->q_perm, S_IRUGO))
 907                         goto out_unlock1;
 908
 909                 ipc_lock_object(&msq->q_perm);
 910
 911                 /* raced with RMID? */
 912                 if (msq->q_perm.deleted) {
 913                         msg = ERR_PTR(-EIDRM);
 914                         goto out_unlock0;
 915                 }
 916
 917                 msg = find_msg(msq, &msgtyp, mode);
 918                 if (!IS_ERR(msg)) {
 919                         /*
 920                          * Found a suitable message.
 921                          * Unlink it from the queue.
 922                          */
 923                         if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
 924                                 msg = ERR_PTR(-E2BIG);
 925                                 goto out_unlock0;
 926                         }
 927                         /*
 928                          * If we are copying, then do not unlink message and do
 929                          * not update queue parameters.
 930                          */
 931                         if (msgflg & MSG_COPY) {
 932                                 msg = copy_msg(msg, copy);
 933                                 goto out_unlock0;
 934                         }
 935
 936                         list_del(&msg->m_list);
 937                         msq->q_qnum--;
 938                         msq->q_rtime = get_seconds();
 939                         msq->q_lrpid = task_tgid_vnr(current);
 940                         msq->q_cbytes -= msg->m_ts;
 941                         atomic_sub(msg->m_ts, &ns->msg_bytes);
 942                         atomic_dec(&ns->msg_hdrs);
 943                         ss_wakeup(&msq->q_senders, 0);
 944
 945                         goto out_unlock0;
 946                 }
 947
 948                 /* No message waiting. Wait for a message */
 949                 if (msgflg & IPC_NOWAIT) {
 950                         msg = ERR_PTR(-ENOMSG);
 951                         goto out_unlock0;
 952                 }
 953
 954                 list_add_tail(&msr_d.r_list, &msq->q_receivers);
 955                 msr_d.r_tsk = current;
 956                 msr_d.r_msgtype = msgtyp;
 957                 msr_d.r_mode = mode;
 958                 if (msgflg & MSG_NOERROR)
 959                         msr_d.r_maxsize = INT_MAX;
 960                 else
 961                         msr_d.r_maxsize = bufsz;
 962                 msr_d.r_msg = ERR_PTR(-EAGAIN);
 963                 current->state = TASK_INTERRUPTIBLE;
 964
 965                 ipc_unlock_object(&msq->q_perm);
 966                 rcu_read_unlock();
 967                 schedule();
 968
 969                 /* Lockless receive, part 1:
 970                  * Disable preemption.  We don't hold a reference to the queue
 971                  * and getting a reference would defeat the idea of a lockless
 972                  * operation, thus the code relies on rcu to guarantee the
 973                  * existence of msq:
 974                  * Prior to destruction, expunge_all(-EIRDM) changes r_msg.
 975                  * Thus if r_msg is -EAGAIN, then the queue not yet destroyed.
 976                  * rcu_read_lock() prevents preemption between reading r_msg
 977                  * and acquiring the q_perm.lock in ipc_lock_object().
 978                  */
 979                 rcu_read_lock();
 980
 981                 /* Lockless receive, part 2:
 982                  * Wait until pipelined_send or expunge_all are outside of
 983                  * wake_up_process(). There is a race with exit(), see
 984                  * ipc/mqueue.c for the details.
 985                  */
 986                 msg = (struct msg_msg*)msr_d.r_msg;
 987                 while (msg == NULL) {
 988                         cpu_relax();
 989                         msg = (struct msg_msg *)msr_d.r_msg;
 990                 }
 991
 992                 /* Lockless receive, part 3:
 993                  * If there is a message or an error then accept it without
 994                  * locking.
 995                  */
 996                 if (msg != ERR_PTR(-EAGAIN))
 997                         goto out_unlock1;
 998
 999                 /* Lockless receive, part 3:
1000                  * Acquire the queue spinlock.
1001                  */
1002                 ipc_lock_object(&msq->q_perm);
1003
1004                 /* Lockless receive, part 4:
1005                  * Repeat test after acquiring the spinlock.
1006                  */
1007                 msg = (struct msg_msg*)msr_d.r_msg;
1008                 if (msg != ERR_PTR(-EAGAIN))
1009                         goto out_unlock0;
1010
1011                 list_del(&msr_d.r_list);
1012                 if (signal_pending(current)) {
1013                         msg = ERR_PTR(-ERESTARTNOHAND);
1014                         goto out_unlock0;
1015                 }
1016
1017                 ipc_unlock_object(&msq->q_perm);
1018         }
1019
1020 out_unlock0:
1021         ipc_unlock_object(&msq->q_perm);
1022 out_unlock1:
1023         rcu_read_unlock();
1024         if (IS_ERR(msg)) {
1025                 free_copy(copy);
1026                 return PTR_ERR(msg);
1027         }
1028
1029         bufsz = msg_handler(buf, msg, bufsz);
1030         free_msg(msg);
1031
1032         return bufsz;
1033 }
1034
1035 SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
1036                 long, msgtyp, int, msgflg)
1037 {
1038         return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill);
1039 }
1040
1041 #ifdef CONFIG_PROC_FS
1042 static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
1043 {
1044         struct user_namespace *user_ns = seq_user_ns(s);
1045         struct msg_queue *msq = it;
1046
1047         return seq_printf(s,
1048                         "%10d %10d  %4o  %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu\n",
1049                         msq->q_perm.key,
1050                         msq->q_perm.id,
1051                         msq->q_perm.mode,
1052                         msq->q_cbytes,
1053                         msq->q_qnum,
1054                         msq->q_lspid,
1055                         msq->q_lrpid,
1056                         from_kuid_munged(user_ns, msq->q_perm.uid),
1057                         from_kgid_munged(user_ns, msq->q_perm.gid),
1058                         from_kuid_munged(user_ns, msq->q_perm.cuid),
1059                         from_kgid_munged(user_ns, msq->q_perm.cgid),
1060                         msq->q_stime,
1061                         msq->q_rtime,
1062                         msq->q_ctime);
1063 }
1064 #endif