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/wake_q.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 <linux/uaccess.h>
  43 #include "util.h"
  44
  45 /* one msg_receiver structure for each sleeping receiver */
  46 struct msg_receiver {
  47         struct list_head        r_list;
  48         struct task_struct      *r_tsk;
  49
  50         int                     r_mode;
  51         long                    r_msgtype;
  52         long                    r_maxsize;
  53
  54         struct msg_msg          *r_msg;
  55 };
  56
  57 /* one msg_sender for each sleeping sender */
  58 struct msg_sender {
  59         struct list_head        list;
  60         struct task_struct      *tsk;
  61         size_t                  msgsz;
  62 };
  63
  64 #define SEARCH_ANY              1
  65 #define SEARCH_EQUAL            2
  66 #define SEARCH_NOTEQUAL         3
  67 #define SEARCH_LESSEQUAL        4
  68 #define SEARCH_NUMBER           5
  69
  70 #define msg_ids(ns)     ((ns)->ids[IPC_MSG_IDS])
  71
  72 static inline struct msg_queue *msq_obtain_object(struct ipc_namespace *ns, int id)
  73 {
  74         struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&msg_ids(ns), id);
  75
  76         if (IS_ERR(ipcp))
  77                 return ERR_CAST(ipcp);
  78
  79         return container_of(ipcp, struct msg_queue, q_perm);
  80 }
  81
  82 static inline struct msg_queue *msq_obtain_object_check(struct ipc_namespace *ns,
  83                                                         int id)
  84 {
  85         struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&msg_ids(ns), id);
  86
  87         if (IS_ERR(ipcp))
  88                 return ERR_CAST(ipcp);
  89
  90         return container_of(ipcp, struct msg_queue, q_perm);
  91 }
  92
  93 static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
  94 {
  95         ipc_rmid(&msg_ids(ns), &s->q_perm);
  96 }
  97
  98 static void msg_rcu_free(struct rcu_head *head)
  99 {
 100         struct kern_ipc_perm *p = container_of(head, struct kern_ipc_perm, rcu);
 101         struct msg_queue *msq = container_of(p, struct msg_queue, q_perm);
 102
 103         security_msg_queue_free(msq);
 104         kvfree(msq);
 105 }
 106
 107 /**
 108  * newque - Create a new msg queue
 109  * @ns: namespace
 110  * @params: ptr to the structure that contains the key and msgflg
 111  *
 112  * Called with msg_ids.rwsem held (writer)
 113  */
 114 static int newque(struct ipc_namespace *ns, struct ipc_params *params)
 115 {
 116         struct msg_queue *msq;
 117         int retval;
 118         key_t key = params->key;
 119         int msgflg = params->flg;
 120
 121         msq = kvmalloc(sizeof(*msq), GFP_KERNEL);
 122         if (unlikely(!msq))
 123                 return -ENOMEM;
 124
 125         msq->q_perm.mode = msgflg & S_IRWXUGO;
 126         msq->q_perm.key = key;
 127
 128         msq->q_perm.security = NULL;
 129         retval = security_msg_queue_alloc(msq);
 130         if (retval) {
 131                 kvfree(msq);
 132                 return retval;
 133         }
 134
 135         msq->q_stime = msq->q_rtime = 0;
 136         msq->q_ctime = ktime_get_real_seconds();
 137         msq->q_cbytes = msq->q_qnum = 0;
 138         msq->q_qbytes = ns->msg_ctlmnb;
 139         msq->q_lspid = msq->q_lrpid = 0;
 140         INIT_LIST_HEAD(&msq->q_messages);
 141         INIT_LIST_HEAD(&msq->q_receivers);
 142         INIT_LIST_HEAD(&msq->q_senders);
 143
 144         /* ipc_addid() locks msq upon success. */
 145         retval = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
 146         if (retval < 0) {
 147                 call_rcu(&msq->q_perm.rcu, msg_rcu_free);
 148                 return retval;
 149         }
 150
 151         ipc_unlock_object(&msq->q_perm);
 152         rcu_read_unlock();
 153
 154         return msq->q_perm.id;
 155 }
 156
 157 static inline bool msg_fits_inqueue(struct msg_queue *msq, size_t msgsz)
 158 {
 159         return msgsz + msq->q_cbytes <= msq->q_qbytes &&
 160                 1 + msq->q_qnum <= msq->q_qbytes;
 161 }
 162
 163 static inline void ss_add(struct msg_queue *msq,
 164                           struct msg_sender *mss, size_t msgsz)
 165 {
 166         mss->tsk = current;
 167         mss->msgsz = msgsz;
 168         __set_current_state(TASK_INTERRUPTIBLE);
 169         list_add_tail(&mss->list, &msq->q_senders);
 170 }
 171
 172 static inline void ss_del(struct msg_sender *mss)
 173 {
 174         if (mss->list.next)
 175                 list_del(&mss->list);
 176 }
 177
 178 static void ss_wakeup(struct msg_queue *msq,
 179                       struct wake_q_head *wake_q, bool kill)
 180 {
 181         struct msg_sender *mss, *t;
 182         struct task_struct *stop_tsk = NULL;
 183         struct list_head *h = &msq->q_senders;
 184
 185         list_for_each_entry_safe(mss, t, h, list) {
 186                 if (kill)
 187                         mss->list.next = NULL;
 188
 189                 /*
 190                  * Stop at the first task we don't wakeup,
 191                  * we've already iterated the original
 192                  * sender queue.
 193                  */
 194                 else if (stop_tsk == mss->tsk)
 195                         break;
 196                 /*
 197                  * We are not in an EIDRM scenario here, therefore
 198                  * verify that we really need to wakeup the task.
 199                  * To maintain current semantics and wakeup order,
 200                  * move the sender to the tail on behalf of the
 201                  * blocked task.
 202                  */
 203                 else if (!msg_fits_inqueue(msq, mss->msgsz)) {
 204                         if (!stop_tsk)
 205                                 stop_tsk = mss->tsk;
 206
 207                         list_move_tail(&mss->list, &msq->q_senders);
 208                         continue;
 209                 }
 210
 211                 wake_q_add(wake_q, mss->tsk);
 212         }
 213 }
 214
 215 static void expunge_all(struct msg_queue *msq, int res,
 216                         struct wake_q_head *wake_q)
 217 {
 218         struct msg_receiver *msr, *t;
 219
 220         list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
 221                 wake_q_add(wake_q, msr->r_tsk);
 222                 WRITE_ONCE(msr->r_msg, ERR_PTR(res));
 223         }
 224 }
 225
 226 /*
 227  * freeque() wakes up waiters on the sender and receiver waiting queue,
 228  * removes the message queue from message queue ID IDR, and cleans up all the
 229  * messages associated with this queue.
 230  *
 231  * msg_ids.rwsem (writer) and the spinlock for this message queue are held
 232  * before freeque() is called. msg_ids.rwsem remains locked on exit.
 233  */
 234 static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
 235 {
 236         struct msg_msg *msg, *t;
 237         struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
 238         DEFINE_WAKE_Q(wake_q);
 239
 240         expunge_all(msq, -EIDRM, &wake_q);
 241         ss_wakeup(msq, &wake_q, true);
 242         msg_rmid(ns, msq);
 243         ipc_unlock_object(&msq->q_perm);
 244         wake_up_q(&wake_q);
 245         rcu_read_unlock();
 246
 247         list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) {
 248                 atomic_dec(&ns->msg_hdrs);
 249                 free_msg(msg);
 250         }
 251         atomic_sub(msq->q_cbytes, &ns->msg_bytes);
 252         ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
 253 }
 254
 255 /*
 256  * Called with msg_ids.rwsem and ipcp locked.
 257  */
 258 static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg)
 259 {
 260         struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
 261
 262         return security_msg_queue_associate(msq, msgflg);
 263 }
 264
 265 SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
 266 {
 267         struct ipc_namespace *ns;
 268         static const struct ipc_ops msg_ops = {
 269                 .getnew = newque,
 270                 .associate = msg_security,
 271         };
 272         struct ipc_params msg_params;
 273
 274         ns = current->nsproxy->ipc_ns;
 275
 276         msg_params.key = key;
 277         msg_params.flg = msgflg;
 278
 279         return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params);
 280 }
 281
 282 static inline unsigned long
 283 copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
 284 {
 285         switch (version) {
 286         case IPC_64:
 287                 return copy_to_user(buf, in, sizeof(*in));
 288         case IPC_OLD:
 289         {
 290                 struct msqid_ds out;
 291
 292                 memset(&out, 0, sizeof(out));
 293
 294                 ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
 295
 296                 out.msg_stime           = in->msg_stime;
 297                 out.msg_rtime           = in->msg_rtime;
 298                 out.msg_ctime           = in->msg_ctime;
 299
 300                 if (in->msg_cbytes > USHRT_MAX)
 301                         out.msg_cbytes  = USHRT_MAX;
 302                 else
 303                         out.msg_cbytes  = in->msg_cbytes;
 304                 out.msg_lcbytes         = in->msg_cbytes;
 305
 306                 if (in->msg_qnum > USHRT_MAX)
 307                         out.msg_qnum    = USHRT_MAX;
 308                 else
 309                         out.msg_qnum    = in->msg_qnum;
 310
 311                 if (in->msg_qbytes > USHRT_MAX)
 312                         out.msg_qbytes  = USHRT_MAX;
 313                 else
 314                         out.msg_qbytes  = in->msg_qbytes;
 315                 out.msg_lqbytes         = in->msg_qbytes;
 316
 317                 out.msg_lspid           = in->msg_lspid;
 318                 out.msg_lrpid           = in->msg_lrpid;
 319
 320                 return copy_to_user(buf, &out, sizeof(out));
 321         }
 322         default:
 323                 return -EINVAL;
 324         }
 325 }
 326
 327 static inline unsigned long
 328 copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version)
 329 {
 330         switch (version) {
 331         case IPC_64:
 332                 if (copy_from_user(out, buf, sizeof(*out)))
 333                         return -EFAULT;
 334                 return 0;
 335         case IPC_OLD:
 336         {
 337                 struct msqid_ds tbuf_old;
 338
 339                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 340                         return -EFAULT;
 341
 342                 out->msg_perm.uid       = tbuf_old.msg_perm.uid;
 343                 out->msg_perm.gid       = tbuf_old.msg_perm.gid;
 344                 out->msg_perm.mode      = tbuf_old.msg_perm.mode;
 345
 346                 if (tbuf_old.msg_qbytes == 0)
 347                         out->msg_qbytes = tbuf_old.msg_lqbytes;
 348                 else
 349                         out->msg_qbytes = tbuf_old.msg_qbytes;
 350
 351                 return 0;
 352         }
 353         default:
 354                 return -EINVAL;
 355         }
 356 }
 357
 358 /*
 359  * This function handles some msgctl commands which require the rwsem
 360  * to be held in write mode.
 361  * NOTE: no locks must be held, the rwsem is taken inside this function.
 362  */
 363 static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
 364                         struct msqid64_ds *msqid64)
 365 {
 366         struct kern_ipc_perm *ipcp;
 367         struct msg_queue *msq;
 368         int err;
 369
 370         down_write(&msg_ids(ns).rwsem);
 371         rcu_read_lock();
 372
 373         ipcp = ipcctl_pre_down_nolock(ns, &msg_ids(ns), msqid, cmd,
 374                                       &msqid64->msg_perm, msqid64->msg_qbytes);
 375         if (IS_ERR(ipcp)) {
 376                 err = PTR_ERR(ipcp);
 377                 goto out_unlock1;
 378         }
 379
 380         msq = container_of(ipcp, struct msg_queue, q_perm);
 381
 382         err = security_msg_queue_msgctl(msq, cmd);
 383         if (err)
 384                 goto out_unlock1;
 385
 386         switch (cmd) {
 387         case IPC_RMID:
 388                 ipc_lock_object(&msq->q_perm);
 389                 /* freeque unlocks the ipc object and rcu */
 390                 freeque(ns, ipcp);
 391                 goto out_up;
 392         case IPC_SET:
 393         {
 394                 DEFINE_WAKE_Q(wake_q);
 395
 396                 if (msqid64->msg_qbytes > ns->msg_ctlmnb &&
 397                     !capable(CAP_SYS_RESOURCE)) {
 398                         err = -EPERM;
 399                         goto out_unlock1;
 400                 }
 401
 402                 ipc_lock_object(&msq->q_perm);
 403                 err = ipc_update_perm(&msqid64->msg_perm, ipcp);
 404                 if (err)
 405                         goto out_unlock0;
 406
 407                 msq->q_qbytes = msqid64->msg_qbytes;
 408
 409                 msq->q_ctime = ktime_get_real_seconds();
 410                 /*
 411                  * Sleeping receivers might be excluded by
 412                  * stricter permissions.
 413                  */
 414                 expunge_all(msq, -EAGAIN, &wake_q);
 415                 /*
 416                  * Sleeping senders might be able to send
 417                  * due to a larger queue size.
 418                  */
 419                 ss_wakeup(msq, &wake_q, false);
 420                 ipc_unlock_object(&msq->q_perm);
 421                 wake_up_q(&wake_q);
 422
 423                 goto out_unlock1;
 424         }
 425         default:
 426                 err = -EINVAL;
 427                 goto out_unlock1;
 428         }
 429
 430 out_unlock0:
 431         ipc_unlock_object(&msq->q_perm);
 432 out_unlock1:
 433         rcu_read_unlock();
 434 out_up:
 435         up_write(&msg_ids(ns).rwsem);
 436         return err;
 437 }
 438
 439 static int msgctl_info(struct ipc_namespace *ns, int msqid,
 440                          int cmd, struct msginfo *msginfo)
 441 {
 442         int err;
 443         int max_id;
 444
 445         /*
 446          * We must not return kernel stack data.
 447          * due to padding, it's not enough
 448          * to set all member fields.
 449          */
 450         err = security_msg_queue_msgctl(NULL, cmd);
 451         if (err)
 452                 return err;
 453
 454         memset(msginfo, 0, sizeof(*msginfo));
 455         msginfo->msgmni = ns->msg_ctlmni;
 456         msginfo->msgmax = ns->msg_ctlmax;
 457         msginfo->msgmnb = ns->msg_ctlmnb;
 458         msginfo->msgssz = MSGSSZ;
 459         msginfo->msgseg = MSGSEG;
 460         down_read(&msg_ids(ns).rwsem);
 461         if (cmd == MSG_INFO) {
 462                 msginfo->msgpool = msg_ids(ns).in_use;
 463                 msginfo->msgmap = atomic_read(&ns->msg_hdrs);
 464                 msginfo->msgtql = atomic_read(&ns->msg_bytes);
 465         } else {
 466                 msginfo->msgmap = MSGMAP;
 467                 msginfo->msgpool = MSGPOOL;
 468                 msginfo->msgtql = MSGTQL;
 469         }
 470         max_id = ipc_get_maxid(&msg_ids(ns));
 471         up_read(&msg_ids(ns).rwsem);
 472         return (max_id < 0) ? 0 : max_id;
 473 }
 474
 475 static int msgctl_stat(struct ipc_namespace *ns, int msqid,
 476                          int cmd, struct msqid64_ds *p)
 477 {
 478         int err;
 479         struct msg_queue *msq;
 480         int success_return;
 481
 482         memset(p, 0, sizeof(*p));
 483
 484         rcu_read_lock();
 485         if (cmd == MSG_STAT) {
 486                 msq = msq_obtain_object(ns, msqid);
 487                 if (IS_ERR(msq)) {
 488                         err = PTR_ERR(msq);
 489                         goto out_unlock;
 490                 }
 491                 success_return = msq->q_perm.id;
 492         } else {
 493                 msq = msq_obtain_object_check(ns, msqid);
 494                 if (IS_ERR(msq)) {
 495                         err = PTR_ERR(msq);
 496                         goto out_unlock;
 497                 }
 498                 success_return = 0;
 499         }
 500
 501         err = -EACCES;
 502         if (ipcperms(ns, &msq->q_perm, S_IRUGO))
 503                 goto out_unlock;
 504
 505         err = security_msg_queue_msgctl(msq, cmd);
 506         if (err)
 507                 goto out_unlock;
 508
 509         kernel_to_ipc64_perm(&msq->q_perm, &p->msg_perm);
 510         p->msg_stime  = msq->q_stime;
 511         p->msg_rtime  = msq->q_rtime;
 512         p->msg_ctime  = msq->q_ctime;
 513         p->msg_cbytes = msq->q_cbytes;
 514         p->msg_qnum   = msq->q_qnum;
 515         p->msg_qbytes = msq->q_qbytes;
 516         p->msg_lspid  = msq->q_lspid;
 517         p->msg_lrpid  = msq->q_lrpid;
 518         rcu_read_unlock();
 519
 520         return success_return;
 521
 522 out_unlock:
 523         rcu_read_unlock();
 524         return err;
 525 }
 526
 527 SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
 528 {
 529         int version;
 530         struct ipc_namespace *ns;
 531         struct msqid64_ds msqid64;
 532         int err;
 533
 534         if (msqid < 0 || cmd < 0)
 535                 return -EINVAL;
 536
 537         version = ipc_parse_version(&cmd);
 538         ns = current->nsproxy->ipc_ns;
 539
 540         switch (cmd) {
 541         case IPC_INFO:
 542         case MSG_INFO: {
 543                 struct msginfo msginfo;
 544                 err = msgctl_info(ns, msqid, cmd, &msginfo);
 545                 if (err < 0)
 546                         return err;
 547                 if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
 548                         err = -EFAULT;
 549                 return err;
 550         }
 551         case MSG_STAT:  /* msqid is an index rather than a msg queue id */
 552         case IPC_STAT:
 553                 err = msgctl_stat(ns, msqid, cmd, &msqid64);
 554                 if (err < 0)
 555                         return err;
 556                 if (copy_msqid_to_user(buf, &msqid64, version))
 557                         err = -EFAULT;
 558                 return err;
 559         case IPC_SET:
 560                 if (copy_msqid_from_user(&msqid64, buf, version))
 561                         return -EFAULT;
 562                 /* fallthru */
 563         case IPC_RMID:
 564                 return msgctl_down(ns, msqid, cmd, &msqid64);
 565         default:
 566                 return  -EINVAL;
 567         }
 568 }
 569
 570 #ifdef CONFIG_COMPAT
 571
 572 struct compat_msqid_ds {
 573         struct compat_ipc_perm msg_perm;
 574         compat_uptr_t msg_first;
 575         compat_uptr_t msg_last;
 576         compat_time_t msg_stime;
 577         compat_time_t msg_rtime;
 578         compat_time_t msg_ctime;
 579         compat_ulong_t msg_lcbytes;
 580         compat_ulong_t msg_lqbytes;
 581         unsigned short msg_cbytes;
 582         unsigned short msg_qnum;
 583         unsigned short msg_qbytes;
 584         compat_ipc_pid_t msg_lspid;
 585         compat_ipc_pid_t msg_lrpid;
 586 };
 587
 588 static int copy_compat_msqid_from_user(struct msqid64_ds *out, void __user *buf,
 589                                         int version)
 590 {
 591         memset(out, 0, sizeof(*out));
 592         if (version == IPC_64) {
 593                 struct compat_msqid64_ds *p = buf;
 594                 if (get_compat_ipc64_perm(&out->msg_perm, &p->msg_perm))
 595                         return -EFAULT;
 596                 if (get_user(out->msg_qbytes, &p->msg_qbytes))
 597                         return -EFAULT;
 598         } else {
 599                 struct compat_msqid_ds *p = buf;
 600                 if (get_compat_ipc_perm(&out->msg_perm, &p->msg_perm))
 601                         return -EFAULT;
 602                 if (get_user(out->msg_qbytes, &p->msg_qbytes))
 603                         return -EFAULT;
 604         }
 605         return 0;
 606 }
 607
 608 static int copy_compat_msqid_to_user(void __user *buf, struct msqid64_ds *in,
 609                                         int version)
 610 {
 611         if (version == IPC_64) {
 612                 struct compat_msqid64_ds v;
 613                 memset(&v, 0, sizeof(v));
 614                 to_compat_ipc64_perm(&v.msg_perm, &in->msg_perm);
 615                 v.msg_stime = in->msg_stime;
 616                 v.msg_rtime = in->msg_rtime;
 617                 v.msg_ctime = in->msg_ctime;
 618                 v.msg_cbytes = in->msg_cbytes;
 619                 v.msg_qnum = in->msg_qnum;
 620                 v.msg_qbytes = in->msg_qbytes;
 621                 v.msg_lspid = in->msg_lspid;
 622                 v.msg_lrpid = in->msg_lrpid;
 623                 return copy_to_user(buf, &v, sizeof(v));
 624         } else {
 625                 struct compat_msqid_ds v;
 626                 memset(&v, 0, sizeof(v));
 627                 to_compat_ipc_perm(&v.msg_perm, &in->msg_perm);
 628                 v.msg_stime = in->msg_stime;
 629                 v.msg_rtime = in->msg_rtime;
 630                 v.msg_ctime = in->msg_ctime;
 631                 v.msg_cbytes = in->msg_cbytes;
 632                 v.msg_qnum = in->msg_qnum;
 633                 v.msg_qbytes = in->msg_qbytes;
 634                 v.msg_lspid = in->msg_lspid;
 635                 v.msg_lrpid = in->msg_lrpid;
 636                 return copy_to_user(buf, &v, sizeof(v));
 637         }
 638 }
 639
 640 COMPAT_SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, void __user *, uptr)
 641 {
 642         struct ipc_namespace *ns;
 643         int err;
 644         struct msqid64_ds msqid64;
 645         int version = compat_ipc_parse_version(&cmd);
 646
 647         ns = current->nsproxy->ipc_ns;
 648
 649         if (msqid < 0 || cmd < 0)
 650                 return -EINVAL;
 651
 652         switch (cmd & (~IPC_64)) {
 653         case IPC_INFO:
 654         case MSG_INFO: {
 655                 struct msginfo msginfo;
 656                 err = msgctl_info(ns, msqid, cmd, &msginfo);
 657                 if (err < 0)
 658                         return err;
 659                 if (copy_to_user(uptr, &msginfo, sizeof(struct msginfo)))
 660                         err = -EFAULT;
 661                 return err;
 662         }
 663         case IPC_STAT:
 664         case MSG_STAT:
 665                 err = msgctl_stat(ns, msqid, cmd, &msqid64);
 666                 if (err < 0)
 667                         return err;
 668                 if (copy_compat_msqid_to_user(uptr, &msqid64, version))
 669                         err = -EFAULT;
 670                 return err;
 671         case IPC_SET:
 672                 if (copy_compat_msqid_from_user(&msqid64, uptr, version))
 673                         return -EFAULT;
 674                 /* fallthru */
 675         case IPC_RMID:
 676                 return msgctl_down(ns, msqid, cmd, &msqid64);
 677         default:
 678                 return -EINVAL;
 679         }
 680 }
 681 #endif
 682
 683 static int testmsg(struct msg_msg *msg, long type, int mode)
 684 {
 685         switch (mode) {
 686         case SEARCH_ANY:
 687         case SEARCH_NUMBER:
 688                 return 1;
 689         case SEARCH_LESSEQUAL:
 690                 if (msg->m_type <= type)
 691                         return 1;
 692                 break;
 693         case SEARCH_EQUAL:
 694                 if (msg->m_type == type)
 695                         return 1;
 696                 break;
 697         case SEARCH_NOTEQUAL:
 698                 if (msg->m_type != type)
 699                         return 1;
 700                 break;
 701         }
 702         return 0;
 703 }
 704
 705 static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg,
 706                                  struct wake_q_head *wake_q)
 707 {
 708         struct msg_receiver *msr, *t;
 709
 710         list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
 711                 if (testmsg(msg, msr->r_msgtype, msr->r_mode) &&
 712                     !security_msg_queue_msgrcv(msq, msg, msr->r_tsk,
 713                                                msr->r_msgtype, msr->r_mode)) {
 714
 715                         list_del(&msr->r_list);
 716                         if (msr->r_maxsize < msg->m_ts) {
 717                                 wake_q_add(wake_q, msr->r_tsk);
 718                                 WRITE_ONCE(msr->r_msg, ERR_PTR(-E2BIG));
 719                         } else {
 720                                 msq->q_lrpid = task_pid_vnr(msr->r_tsk);
 721                                 msq->q_rtime = get_seconds();
 722
 723                                 wake_q_add(wake_q, msr->r_tsk);
 724                                 WRITE_ONCE(msr->r_msg, msg);
 725                                 return 1;
 726                         }
 727                 }
 728         }
 729
 730         return 0;
 731 }
 732
 733 static long do_msgsnd(int msqid, long mtype, void __user *mtext,
 734                 size_t msgsz, int msgflg)
 735 {
 736         struct msg_queue *msq;
 737         struct msg_msg *msg;
 738         int err;
 739         struct ipc_namespace *ns;
 740         DEFINE_WAKE_Q(wake_q);
 741
 742         ns = current->nsproxy->ipc_ns;
 743
 744         if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0)
 745                 return -EINVAL;
 746         if (mtype < 1)
 747                 return -EINVAL;
 748
 749         msg = load_msg(mtext, msgsz);
 750         if (IS_ERR(msg))
 751                 return PTR_ERR(msg);
 752
 753         msg->m_type = mtype;
 754         msg->m_ts = msgsz;
 755
 756         rcu_read_lock();
 757         msq = msq_obtain_object_check(ns, msqid);
 758         if (IS_ERR(msq)) {
 759                 err = PTR_ERR(msq);
 760                 goto out_unlock1;
 761         }
 762
 763         ipc_lock_object(&msq->q_perm);
 764
 765         for (;;) {
 766                 struct msg_sender s;
 767
 768                 err = -EACCES;
 769                 if (ipcperms(ns, &msq->q_perm, S_IWUGO))
 770                         goto out_unlock0;
 771
 772                 /* raced with RMID? */
 773                 if (!ipc_valid_object(&msq->q_perm)) {
 774                         err = -EIDRM;
 775                         goto out_unlock0;
 776                 }
 777
 778                 err = security_msg_queue_msgsnd(msq, msg, msgflg);
 779                 if (err)
 780                         goto out_unlock0;
 781
 782                 if (msg_fits_inqueue(msq, msgsz))
 783                         break;
 784
 785                 /* queue full, wait: */
 786                 if (msgflg & IPC_NOWAIT) {
 787                         err = -EAGAIN;
 788                         goto out_unlock0;
 789                 }
 790
 791                 /* enqueue the sender and prepare to block */
 792                 ss_add(msq, &s, msgsz);
 793
 794                 if (!ipc_rcu_getref(&msq->q_perm)) {
 795                         err = -EIDRM;
 796                         goto out_unlock0;
 797                 }
 798
 799                 ipc_unlock_object(&msq->q_perm);
 800                 rcu_read_unlock();
 801                 schedule();
 802
 803                 rcu_read_lock();
 804                 ipc_lock_object(&msq->q_perm);
 805
 806                 ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
 807                 /* raced with RMID? */
 808                 if (!ipc_valid_object(&msq->q_perm)) {
 809                         err = -EIDRM;
 810                         goto out_unlock0;
 811                 }
 812                 ss_del(&s);
 813
 814                 if (signal_pending(current)) {
 815                         err = -ERESTARTNOHAND;
 816                         goto out_unlock0;
 817                 }
 818
 819         }
 820
 821         msq->q_lspid = task_tgid_vnr(current);
 822         msq->q_stime = get_seconds();
 823
 824         if (!pipelined_send(msq, msg, &wake_q)) {
 825                 /* no one is waiting for this message, enqueue it */
 826                 list_add_tail(&msg->m_list, &msq->q_messages);
 827                 msq->q_cbytes += msgsz;
 828                 msq->q_qnum++;
 829                 atomic_add(msgsz, &ns->msg_bytes);
 830                 atomic_inc(&ns->msg_hdrs);
 831         }
 832
 833         err = 0;
 834         msg = NULL;
 835
 836 out_unlock0:
 837         ipc_unlock_object(&msq->q_perm);
 838         wake_up_q(&wake_q);
 839 out_unlock1:
 840         rcu_read_unlock();
 841         if (msg != NULL)
 842                 free_msg(msg);
 843         return err;
 844 }
 845
 846 SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
 847                 int, msgflg)
 848 {
 849         long mtype;
 850
 851         if (get_user(mtype, &msgp->mtype))
 852                 return -EFAULT;
 853         return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg);
 854 }
 855
 856 #ifdef CONFIG_COMPAT
 857
 858 struct compat_msgbuf {
 859         compat_long_t mtype;
 860         char mtext[1];
 861 };
 862
 863 COMPAT_SYSCALL_DEFINE4(msgsnd, int, msqid, compat_uptr_t, msgp,
 864                        compat_ssize_t, msgsz, int, msgflg)
 865 {
 866         struct compat_msgbuf __user *up = compat_ptr(msgp);
 867         compat_long_t mtype;
 868
 869         if (get_user(mtype, &up->mtype))
 870                 return -EFAULT;
 871         return do_msgsnd(msqid, mtype, up->mtext, (ssize_t)msgsz, msgflg);
 872 }
 873 #endif
 874
 875 static inline int convert_mode(long *msgtyp, int msgflg)
 876 {
 877         if (msgflg & MSG_COPY)
 878                 return SEARCH_NUMBER;
 879         /*
 880          *  find message of correct type.
 881          *  msgtyp = 0 => get first.
 882          *  msgtyp > 0 => get first message of matching type.
 883          *  msgtyp < 0 => get message with least type must be < abs(msgtype).
 884          */
 885         if (*msgtyp == 0)
 886                 return SEARCH_ANY;
 887         if (*msgtyp < 0) {
 888                 if (*msgtyp == LONG_MIN) /* -LONG_MIN is undefined */
 889                         *msgtyp = LONG_MAX;
 890                 else
 891                         *msgtyp = -*msgtyp;
 892                 return SEARCH_LESSEQUAL;
 893         }
 894         if (msgflg & MSG_EXCEPT)
 895                 return SEARCH_NOTEQUAL;
 896         return SEARCH_EQUAL;
 897 }
 898
 899 static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
 900 {
 901         struct msgbuf __user *msgp = dest;
 902         size_t msgsz;
 903
 904         if (put_user(msg->m_type, &msgp->mtype))
 905                 return -EFAULT;
 906
 907         msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
 908         if (store_msg(msgp->mtext, msg, msgsz))
 909                 return -EFAULT;
 910         return msgsz;
 911 }
 912
 913 #ifdef CONFIG_CHECKPOINT_RESTORE
 914 /*
 915  * This function creates new kernel message structure, large enough to store
 916  * bufsz message bytes.
 917  */
 918 static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
 919 {
 920         struct msg_msg *copy;
 921
 922         /*
 923          * Create dummy message to copy real message to.
 924          */
 925         copy = load_msg(buf, bufsz);
 926         if (!IS_ERR(copy))
 927                 copy->m_ts = bufsz;
 928         return copy;
 929 }
 930
 931 static inline void free_copy(struct msg_msg *copy)
 932 {
 933         if (copy)
 934                 free_msg(copy);
 935 }
 936 #else
 937 static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
 938 {
 939         return ERR_PTR(-ENOSYS);
 940 }
 941
 942 static inline void free_copy(struct msg_msg *copy)
 943 {
 944 }
 945 #endif
 946
 947 static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode)
 948 {
 949         struct msg_msg *msg, *found = NULL;
 950         long count = 0;
 951
 952         list_for_each_entry(msg, &msq->q_messages, m_list) {
 953                 if (testmsg(msg, *msgtyp, mode) &&
 954                     !security_msg_queue_msgrcv(msq, msg, current,
 955                                                *msgtyp, mode)) {
 956                         if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) {
 957                                 *msgtyp = msg->m_type - 1;
 958                                 found = msg;
 959                         } else if (mode == SEARCH_NUMBER) {
 960                                 if (*msgtyp == count)
 961                                         return msg;
 962                         } else
 963                                 return msg;
 964                         count++;
 965                 }
 966         }
 967
 968         return found ?: ERR_PTR(-EAGAIN);
 969 }
 970
 971 static long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg,
 972                long (*msg_handler)(void __user *, struct msg_msg *, size_t))
 973 {
 974         int mode;
 975         struct msg_queue *msq;
 976         struct ipc_namespace *ns;
 977         struct msg_msg *msg, *copy = NULL;
 978         DEFINE_WAKE_Q(wake_q);
 979
 980         ns = current->nsproxy->ipc_ns;
 981
 982         if (msqid < 0 || (long) bufsz < 0)
 983                 return -EINVAL;
 984
 985         if (msgflg & MSG_COPY) {
 986                 if ((msgflg & MSG_EXCEPT) || !(msgflg & IPC_NOWAIT))
 987                         return -EINVAL;
 988                 copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax));
 989                 if (IS_ERR(copy))
 990                         return PTR_ERR(copy);
 991         }
 992         mode = convert_mode(&msgtyp, msgflg);
 993
 994         rcu_read_lock();
 995         msq = msq_obtain_object_check(ns, msqid);
 996         if (IS_ERR(msq)) {
 997                 rcu_read_unlock();
 998                 free_copy(copy);
 999                 return PTR_ERR(msq);
1000         }
1001
1002         for (;;) {
1003                 struct msg_receiver msr_d;
1004
1005                 msg = ERR_PTR(-EACCES);
1006                 if (ipcperms(ns, &msq->q_perm, S_IRUGO))
1007                         goto out_unlock1;
1008
1009                 ipc_lock_object(&msq->q_perm);
1010
1011                 /* raced with RMID? */
1012                 if (!ipc_valid_object(&msq->q_perm)) {
1013                         msg = ERR_PTR(-EIDRM);
1014                         goto out_unlock0;
1015                 }
1016
1017                 msg = find_msg(msq, &msgtyp, mode);
1018                 if (!IS_ERR(msg)) {
1019                         /*
1020                          * Found a suitable message.
1021                          * Unlink it from the queue.
1022                          */
1023                         if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
1024                                 msg = ERR_PTR(-E2BIG);
1025                                 goto out_unlock0;
1026                         }
1027                         /*
1028                          * If we are copying, then do not unlink message and do
1029                          * not update queue parameters.
1030                          */
1031                         if (msgflg & MSG_COPY) {
1032                                 msg = copy_msg(msg, copy);
1033                                 goto out_unlock0;
1034                         }
1035
1036                         list_del(&msg->m_list);
1037                         msq->q_qnum--;
1038                         msq->q_rtime = get_seconds();
1039                         msq->q_lrpid = task_tgid_vnr(current);
1040                         msq->q_cbytes -= msg->m_ts;
1041                         atomic_sub(msg->m_ts, &ns->msg_bytes);
1042                         atomic_dec(&ns->msg_hdrs);
1043                         ss_wakeup(msq, &wake_q, false);
1044
1045                         goto out_unlock0;
1046                 }
1047
1048                 /* No message waiting. Wait for a message */
1049                 if (msgflg & IPC_NOWAIT) {
1050                         msg = ERR_PTR(-ENOMSG);
1051                         goto out_unlock0;
1052                 }
1053
1054                 list_add_tail(&msr_d.r_list, &msq->q_receivers);
1055                 msr_d.r_tsk = current;
1056                 msr_d.r_msgtype = msgtyp;
1057                 msr_d.r_mode = mode;
1058                 if (msgflg & MSG_NOERROR)
1059                         msr_d.r_maxsize = INT_MAX;
1060                 else
1061                         msr_d.r_maxsize = bufsz;
1062                 msr_d.r_msg = ERR_PTR(-EAGAIN);
1063                 __set_current_state(TASK_INTERRUPTIBLE);
1064
1065                 ipc_unlock_object(&msq->q_perm);
1066                 rcu_read_unlock();
1067                 schedule();
1068
1069                 /*
1070                  * Lockless receive, part 1:
1071                  * We don't hold a reference to the queue and getting a
1072                  * reference would defeat the idea of a lockless operation,
1073                  * thus the code relies on rcu to guarantee the existence of
1074                  * msq:
1075                  * Prior to destruction, expunge_all(-EIRDM) changes r_msg.
1076                  * Thus if r_msg is -EAGAIN, then the queue not yet destroyed.
1077                  */
1078                 rcu_read_lock();
1079
1080                 /*
1081                  * Lockless receive, part 2:
1082                  * The work in pipelined_send() and expunge_all():
1083                  * - Set pointer to message
1084                  * - Queue the receiver task for later wakeup
1085                  * - Wake up the process after the lock is dropped.
1086                  *
1087                  * Should the process wake up before this wakeup (due to a
1088                  * signal) it will either see the message and continue ...
1089                  */
1090                 msg = READ_ONCE(msr_d.r_msg);
1091                 if (msg != ERR_PTR(-EAGAIN))
1092                         goto out_unlock1;
1093
1094                  /*
1095                   * ... or see -EAGAIN, acquire the lock to check the message
1096                   * again.
1097                   */
1098                 ipc_lock_object(&msq->q_perm);
1099
1100                 msg = msr_d.r_msg;
1101                 if (msg != ERR_PTR(-EAGAIN))
1102                         goto out_unlock0;
1103
1104                 list_del(&msr_d.r_list);
1105                 if (signal_pending(current)) {
1106                         msg = ERR_PTR(-ERESTARTNOHAND);
1107                         goto out_unlock0;
1108                 }
1109
1110                 ipc_unlock_object(&msq->q_perm);
1111         }
1112
1113 out_unlock0:
1114         ipc_unlock_object(&msq->q_perm);
1115         wake_up_q(&wake_q);
1116 out_unlock1:
1117         rcu_read_unlock();
1118         if (IS_ERR(msg)) {
1119                 free_copy(copy);
1120                 return PTR_ERR(msg);
1121         }
1122
1123         bufsz = msg_handler(buf, msg, bufsz);
1124         free_msg(msg);
1125
1126         return bufsz;
1127 }
1128
1129 SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
1130                 long, msgtyp, int, msgflg)
1131 {
1132         return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill);
1133 }
1134
1135 #ifdef CONFIG_COMPAT
1136 static long compat_do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
1137 {
1138         struct compat_msgbuf __user *msgp = dest;
1139         size_t msgsz;
1140
1141         if (put_user(msg->m_type, &msgp->mtype))
1142                 return -EFAULT;
1143
1144         msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
1145         if (store_msg(msgp->mtext, msg, msgsz))
1146                 return -EFAULT;
1147         return msgsz;
1148 }
1149
1150 COMPAT_SYSCALL_DEFINE5(msgrcv, int, msqid, compat_uptr_t, msgp,
1151                        compat_ssize_t, msgsz, compat_long_t, msgtyp, int, msgflg)
1152 {
1153         return do_msgrcv(msqid, compat_ptr(msgp), (ssize_t)msgsz, (long)msgtyp,
1154                          msgflg, compat_do_msg_fill);
1155 }
1156 #endif
1157
1158 int msg_init_ns(struct ipc_namespace *ns)
1159 {
1160         ns->msg_ctlmax = MSGMAX;
1161         ns->msg_ctlmnb = MSGMNB;
1162         ns->msg_ctlmni = MSGMNI;
1163
1164         atomic_set(&ns->msg_bytes, 0);
1165         atomic_set(&ns->msg_hdrs, 0);
1166         return ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
1167 }
1168
1169 #ifdef CONFIG_IPC_NS
1170 void msg_exit_ns(struct ipc_namespace *ns)
1171 {
1172         free_ipcs(ns, &msg_ids(ns), freeque);
1173         idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr);
1174         rhashtable_destroy(&ns->ids[IPC_MSG_IDS].key_ht);
1175 }
1176 #endif
1177
1178 #ifdef CONFIG_PROC_FS
1179 static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
1180 {
1181         struct user_namespace *user_ns = seq_user_ns(s);
1182         struct kern_ipc_perm *ipcp = it;
1183         struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
1184
1185         seq_printf(s,
1186                    "%10d %10d  %4o  %10lu %10lu %5u %5u %5u %5u %5u %5u %10llu %10llu %10llu\n",
1187                    msq->q_perm.key,
1188                    msq->q_perm.id,
1189                    msq->q_perm.mode,
1190                    msq->q_cbytes,
1191                    msq->q_qnum,
1192                    msq->q_lspid,
1193                    msq->q_lrpid,
1194                    from_kuid_munged(user_ns, msq->q_perm.uid),
1195                    from_kgid_munged(user_ns, msq->q_perm.gid),
1196                    from_kuid_munged(user_ns, msq->q_perm.cuid),
1197                    from_kgid_munged(user_ns, msq->q_perm.cgid),
1198                    msq->q_stime,
1199                    msq->q_rtime,
1200                    msq->q_ctime);
1201
1202         return 0;
1203 }
1204 #endif
1205
1206 int __init msg_init(void)
1207 {
1208         const int err = msg_init_ns(&init_ipc_ns);
1209
1210         ipc_init_proc_interface("sysvipc/msg",
1211                                 "       key      msqid perms      cbytes       qnum lspid lrpid   uid   gid  cuid  cgid      stime      rtime      ctime\n",
1212                                 IPC_MSG_IDS, sysvipc_msg_proc_show);
1213         return err;
1214 }