ipc/msg.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * linux/ipc/msg.c
   4  * Copyright (C) 1992 Krishna Balasubramanian
   5  *
   6  * Removed all the remaining kerneld mess
   7  * Catch the -EFAULT stuff properly
   8  * Use GFP_KERNEL for messages as in 1.2
   9  * Fixed up the unchecked user space derefs
  10  * Copyright (C) 1998 Alan Cox & Andi Kleen
  11  *
  12  * /proc/sysvipc/msg support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
  13  *
  14  * mostly rewritten, threaded and wake-one semantics added
  15  * MSGMAX limit removed, sysctl's added
  16  * (c) 1999 Manfred Spraul <manfred@colorfullife.com>
  17  *
  18  * support for audit of ipc object properties and permission changes
  19  * Dustin Kirkland <dustin.kirkland@us.ibm.com>
  20  *
  21  * namespaces support
  22  * OpenVZ, SWsoft Inc.
  23  * Pavel Emelianov <xemul@openvz.org>
  24  */
  25
  26 #include <linux/capability.h>
  27 #include <linux/msg.h>
  28 #include <linux/spinlock.h>
  29 #include <linux/init.h>
  30 #include <linux/mm.h>
  31 #include <linux/proc_fs.h>
  32 #include <linux/list.h>
  33 #include <linux/security.h>
  34 #include <linux/sched/wake_q.h>
  35 #include <linux/syscalls.h>
  36 #include <linux/audit.h>
  37 #include <linux/seq_file.h>
  38 #include <linux/rwsem.h>
  39 #include <linux/nsproxy.h>
  40 #include <linux/ipc_namespace.h>
  41
  42 #include <asm/current.h>
  43 #include <linux/uaccess.h>
  44 #include "util.h"
  45
  46 /* one msg_receiver structure for each sleeping receiver */
  47 struct msg_receiver {
  48         struct list_head        r_list;
  49         struct task_struct      *r_tsk;
  50
  51         int                     r_mode;
  52         long                    r_msgtype;
  53         long                    r_maxsize;
  54
  55         struct msg_msg          *r_msg;
  56 };
  57
  58 /* one msg_sender for each sleeping sender */
  59 struct msg_sender {
  60         struct list_head        list;
  61         struct task_struct      *tsk;
  62         size_t                  msgsz;
  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 inline struct msg_queue *msq_obtain_object(struct ipc_namespace *ns, int id)
  74 {
  75         struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&msg_ids(ns), id);
  76
  77         if (IS_ERR(ipcp))
  78                 return ERR_CAST(ipcp);
  79
  80         return container_of(ipcp, struct msg_queue, q_perm);
  81 }
  82
  83 static inline struct msg_queue *msq_obtain_object_check(struct ipc_namespace *ns,
  84                                                         int id)
  85 {
  86         struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&msg_ids(ns), id);
  87
  88         if (IS_ERR(ipcp))
  89                 return ERR_CAST(ipcp);
  90
  91         return container_of(ipcp, struct msg_queue, q_perm);
  92 }
  93
  94 static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
  95 {
  96         ipc_rmid(&msg_ids(ns), &s->q_perm);
  97 }
  98
  99 static void msg_rcu_free(struct rcu_head *head)
 100 {
 101         struct kern_ipc_perm *p = container_of(head, struct kern_ipc_perm, rcu);
 102         struct msg_queue *msq = container_of(p, struct msg_queue, q_perm);
 103
 104         security_msg_queue_free(msq);
 105         kvfree(msq);
 106 }
 107
 108 /**
 109  * newque - Create a new msg queue
 110  * @ns: namespace
 111  * @params: ptr to the structure that contains the key and msgflg
 112  *
 113  * Called with msg_ids.rwsem held (writer)
 114  */
 115 static int newque(struct ipc_namespace *ns, struct ipc_params *params)
 116 {
 117         struct msg_queue *msq;
 118         int retval;
 119         key_t key = params->key;
 120         int msgflg = params->flg;
 121
 122         msq = kvmalloc(sizeof(*msq), GFP_KERNEL);
 123         if (unlikely(!msq))
 124                 return -ENOMEM;
 125
 126         msq->q_perm.mode = msgflg & S_IRWXUGO;
 127         msq->q_perm.key = key;
 128
 129         msq->q_perm.security = NULL;
 130         retval = security_msg_queue_alloc(msq);
 131         if (retval) {
 132                 kvfree(msq);
 133                 return retval;
 134         }
 135
 136         msq->q_stime = msq->q_rtime = 0;
 137         msq->q_ctime = ktime_get_real_seconds();
 138         msq->q_cbytes = msq->q_qnum = 0;
 139         msq->q_qbytes = ns->msg_ctlmnb;
 140         msq->q_lspid = msq->q_lrpid = 0;
 141         INIT_LIST_HEAD(&msq->q_messages);
 142         INIT_LIST_HEAD(&msq->q_receivers);
 143         INIT_LIST_HEAD(&msq->q_senders);
 144
 145         /* ipc_addid() locks msq upon success. */
 146         retval = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
 147         if (retval < 0) {
 148                 call_rcu(&msq->q_perm.rcu, msg_rcu_free);
 149                 return retval;
 150         }
 151
 152         ipc_unlock_object(&msq->q_perm);
 153         rcu_read_unlock();
 154
 155         return msq->q_perm.id;
 156 }
 157
 158 static inline bool msg_fits_inqueue(struct msg_queue *msq, size_t msgsz)
 159 {
 160         return msgsz + msq->q_cbytes <= msq->q_qbytes &&
 161                 1 + msq->q_qnum <= msq->q_qbytes;
 162 }
 163
 164 static inline void ss_add(struct msg_queue *msq,
 165                           struct msg_sender *mss, size_t msgsz)
 166 {
 167         mss->tsk = current;
 168         mss->msgsz = msgsz;
 169         __set_current_state(TASK_INTERRUPTIBLE);
 170         list_add_tail(&mss->list, &msq->q_senders);
 171 }
 172
 173 static inline void ss_del(struct msg_sender *mss)
 174 {
 175         if (mss->list.next)
 176                 list_del(&mss->list);
 177 }
 178
 179 static void ss_wakeup(struct msg_queue *msq,
 180                       struct wake_q_head *wake_q, bool kill)
 181 {
 182         struct msg_sender *mss, *t;
 183         struct task_struct *stop_tsk = NULL;
 184         struct list_head *h = &msq->q_senders;
 185
 186         list_for_each_entry_safe(mss, t, h, list) {
 187                 if (kill)
 188                         mss->list.next = NULL;
 189
 190                 /*
 191                  * Stop at the first task we don't wakeup,
 192                  * we've already iterated the original
 193                  * sender queue.
 194                  */
 195                 else if (stop_tsk == mss->tsk)
 196                         break;
 197                 /*
 198                  * We are not in an EIDRM scenario here, therefore
 199                  * verify that we really need to wakeup the task.
 200                  * To maintain current semantics and wakeup order,
 201                  * move the sender to the tail on behalf of the
 202                  * blocked task.
 203                  */
 204                 else if (!msg_fits_inqueue(msq, mss->msgsz)) {
 205                         if (!stop_tsk)
 206                                 stop_tsk = mss->tsk;
 207
 208                         list_move_tail(&mss->list, &msq->q_senders);
 209                         continue;
 210                 }
 211
 212                 wake_q_add(wake_q, mss->tsk);
 213         }
 214 }
 215
 216 static void expunge_all(struct msg_queue *msq, int res,
 217                         struct wake_q_head *wake_q)
 218 {
 219         struct msg_receiver *msr, *t;
 220
 221         list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
 222                 wake_q_add(wake_q, msr->r_tsk);
 223                 WRITE_ONCE(msr->r_msg, ERR_PTR(res));
 224         }
 225 }
 226
 227 /*
 228  * freeque() wakes up waiters on the sender and receiver waiting queue,
 229  * removes the message queue from message queue ID IDR, and cleans up all the
 230  * messages associated with this queue.
 231  *
 232  * msg_ids.rwsem (writer) and the spinlock for this message queue are held
 233  * before freeque() is called. msg_ids.rwsem remains locked on exit.
 234  */
 235 static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
 236 {
 237         struct msg_msg *msg, *t;
 238         struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
 239         DEFINE_WAKE_Q(wake_q);
 240
 241         expunge_all(msq, -EIDRM, &wake_q);
 242         ss_wakeup(msq, &wake_q, true);
 243         msg_rmid(ns, msq);
 244         ipc_unlock_object(&msq->q_perm);
 245         wake_up_q(&wake_q);
 246         rcu_read_unlock();
 247
 248         list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) {
 249                 atomic_dec(&ns->msg_hdrs);
 250                 free_msg(msg);
 251         }
 252         atomic_sub(msq->q_cbytes, &ns->msg_bytes);
 253         ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
 254 }
 255
 256 /*
 257  * Called with msg_ids.rwsem and ipcp locked.
 258  */
 259 static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg)
 260 {
 261         struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
 262
 263         return security_msg_queue_associate(msq, msgflg);
 264 }
 265
 266 SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
 267 {
 268         struct ipc_namespace *ns;
 269         static const struct ipc_ops msg_ops = {
 270                 .getnew = newque,
 271                 .associate = msg_security,
 272         };
 273         struct ipc_params msg_params;
 274
 275         ns = current->nsproxy->ipc_ns;
 276
 277         msg_params.key = key;
 278         msg_params.flg = msgflg;
 279
 280         return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params);
 281 }
 282
 283 static inline unsigned long
 284 copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
 285 {
 286         switch (version) {
 287         case IPC_64:
 288                 return copy_to_user(buf, in, sizeof(*in));
 289         case IPC_OLD:
 290         {
 291                 struct msqid_ds out;
 292
 293                 memset(&out, 0, sizeof(out));
 294
 295                 ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
 296
 297                 out.msg_stime           = in->msg_stime;
 298                 out.msg_rtime           = in->msg_rtime;
 299                 out.msg_ctime           = in->msg_ctime;
 300
 301                 if (in->msg_cbytes > USHRT_MAX)
 302                         out.msg_cbytes  = USHRT_MAX;
 303                 else
 304                         out.msg_cbytes  = in->msg_cbytes;
 305                 out.msg_lcbytes         = in->msg_cbytes;
 306
 307                 if (in->msg_qnum > USHRT_MAX)
 308                         out.msg_qnum    = USHRT_MAX;
 309                 else
 310                         out.msg_qnum    = in->msg_qnum;
 311
 312                 if (in->msg_qbytes > USHRT_MAX)
 313                         out.msg_qbytes  = USHRT_MAX;
 314                 else
 315                         out.msg_qbytes  = in->msg_qbytes;
 316                 out.msg_lqbytes         = in->msg_qbytes;
 317
 318                 out.msg_lspid           = in->msg_lspid;
 319                 out.msg_lrpid           = in->msg_lrpid;
 320
 321                 return copy_to_user(buf, &out, sizeof(out));
 322         }
 323         default:
 324                 return -EINVAL;
 325         }
 326 }
 327
 328 static inline unsigned long
 329 copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version)
 330 {
 331         switch (version) {
 332         case IPC_64:
 333                 if (copy_from_user(out, buf, sizeof(*out)))
 334                         return -EFAULT;
 335                 return 0;
 336         case IPC_OLD:
 337         {
 338                 struct msqid_ds tbuf_old;
 339
 340                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 341                         return -EFAULT;
 342
 343                 out->msg_perm.uid       = tbuf_old.msg_perm.uid;
 344                 out->msg_perm.gid       = tbuf_old.msg_perm.gid;
 345                 out->msg_perm.mode      = tbuf_old.msg_perm.mode;
 346
 347                 if (tbuf_old.msg_qbytes == 0)
 348                         out->msg_qbytes = tbuf_old.msg_lqbytes;
 349                 else
 350                         out->msg_qbytes = tbuf_old.msg_qbytes;
 351
 352                 return 0;
 353         }
 354         default:
 355                 return -EINVAL;
 356         }
 357 }
 358
 359 /*
 360  * This function handles some msgctl commands which require the rwsem
 361  * to be held in write mode.
 362  * NOTE: no locks must be held, the rwsem is taken inside this function.
 363  */
 364 static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
 365                         struct msqid64_ds *msqid64)
 366 {
 367         struct kern_ipc_perm *ipcp;
 368         struct msg_queue *msq;
 369         int err;
 370
 371         down_write(&msg_ids(ns).rwsem);
 372         rcu_read_lock();
 373
 374         ipcp = ipcctl_pre_down_nolock(ns, &msg_ids(ns), msqid, cmd,
 375                                       &msqid64->msg_perm, msqid64->msg_qbytes);
 376         if (IS_ERR(ipcp)) {
 377                 err = PTR_ERR(ipcp);
 378                 goto out_unlock1;
 379         }
 380
 381         msq = container_of(ipcp, struct msg_queue, q_perm);
 382
 383         err = security_msg_queue_msgctl(msq, cmd);
 384         if (err)
 385                 goto out_unlock1;
 386
 387         switch (cmd) {
 388         case IPC_RMID:
 389                 ipc_lock_object(&msq->q_perm);
 390                 /* freeque unlocks the ipc object and rcu */
 391                 freeque(ns, ipcp);
 392                 goto out_up;
 393         case IPC_SET:
 394         {
 395                 DEFINE_WAKE_Q(wake_q);
 396
 397                 if (msqid64->msg_qbytes > ns->msg_ctlmnb &&
 398                     !capable(CAP_SYS_RESOURCE)) {
 399                         err = -EPERM;
 400                         goto out_unlock1;
 401                 }
 402
 403                 ipc_lock_object(&msq->q_perm);
 404                 err = ipc_update_perm(&msqid64->msg_perm, ipcp);
 405                 if (err)
 406                         goto out_unlock0;
 407
 408                 msq->q_qbytes = msqid64->msg_qbytes;
 409
 410                 msq->q_ctime = ktime_get_real_seconds();
 411                 /*
 412                  * Sleeping receivers might be excluded by
 413                  * stricter permissions.
 414                  */
 415                 expunge_all(msq, -EAGAIN, &wake_q);
 416                 /*
 417                  * Sleeping senders might be able to send
 418                  * due to a larger queue size.
 419                  */
 420                 ss_wakeup(msq, &wake_q, false);
 421                 ipc_unlock_object(&msq->q_perm);
 422                 wake_up_q(&wake_q);
 423
 424                 goto out_unlock1;
 425         }
 426         default:
 427                 err = -EINVAL;
 428                 goto out_unlock1;
 429         }
 430
 431 out_unlock0:
 432         ipc_unlock_object(&msq->q_perm);
 433 out_unlock1:
 434         rcu_read_unlock();
 435 out_up:
 436         up_write(&msg_ids(ns).rwsem);
 437         return err;
 438 }
 439
 440 static int msgctl_info(struct ipc_namespace *ns, int msqid,
 441                          int cmd, struct msginfo *msginfo)
 442 {
 443         int err;
 444         int max_id;
 445
 446         /*
 447          * We must not return kernel stack data.
 448          * due to padding, it's not enough
 449          * to set all member fields.
 450          */
 451         err = security_msg_queue_msgctl(NULL, cmd);
 452         if (err)
 453                 return err;
 454
 455         memset(msginfo, 0, sizeof(*msginfo));
 456         msginfo->msgmni = ns->msg_ctlmni;
 457         msginfo->msgmax = ns->msg_ctlmax;
 458         msginfo->msgmnb = ns->msg_ctlmnb;
 459         msginfo->msgssz = MSGSSZ;
 460         msginfo->msgseg = MSGSEG;
 461         down_read(&msg_ids(ns).rwsem);
 462         if (cmd == MSG_INFO) {
 463                 msginfo->msgpool = msg_ids(ns).in_use;
 464                 msginfo->msgmap = atomic_read(&ns->msg_hdrs);
 465                 msginfo->msgtql = atomic_read(&ns->msg_bytes);
 466         } else {
 467                 msginfo->msgmap = MSGMAP;
 468                 msginfo->msgpool = MSGPOOL;
 469                 msginfo->msgtql = MSGTQL;
 470         }
 471         max_id = ipc_get_maxid(&msg_ids(ns));
 472         up_read(&msg_ids(ns).rwsem);
 473         return (max_id < 0) ? 0 : max_id;
 474 }
 475
 476 static int msgctl_stat(struct ipc_namespace *ns, int msqid,
 477                          int cmd, struct msqid64_ds *p)
 478 {
 479         int err;
 480         struct msg_queue *msq;
 481         int success_return;
 482
 483         memset(p, 0, sizeof(*p));
 484
 485         rcu_read_lock();
 486         if (cmd == MSG_STAT) {
 487                 msq = msq_obtain_object(ns, msqid);
 488                 if (IS_ERR(msq)) {
 489                         err = PTR_ERR(msq);
 490                         goto out_unlock;
 491                 }
 492                 success_return = msq->q_perm.id;
 493         } else {
 494                 msq = msq_obtain_object_check(ns, msqid);
 495                 if (IS_ERR(msq)) {
 496                         err = PTR_ERR(msq);
 497                         goto out_unlock;
 498                 }
 499                 success_return = 0;
 500         }
 501
 502         err = -EACCES;
 503         if (ipcperms(ns, &msq->q_perm, S_IRUGO))
 504                 goto out_unlock;
 505
 506         err = security_msg_queue_msgctl(msq, cmd);
 507         if (err)
 508                 goto out_unlock;
 509
 510         kernel_to_ipc64_perm(&msq->q_perm, &p->msg_perm);
 511         p->msg_stime  = msq->q_stime;
 512         p->msg_rtime  = msq->q_rtime;
 513         p->msg_ctime  = msq->q_ctime;
 514         p->msg_cbytes = msq->q_cbytes;
 515         p->msg_qnum   = msq->q_qnum;
 516         p->msg_qbytes = msq->q_qbytes;
 517         p->msg_lspid  = msq->q_lspid;
 518         p->msg_lrpid  = msq->q_lrpid;
 519         rcu_read_unlock();
 520
 521         return success_return;
 522
 523 out_unlock:
 524         rcu_read_unlock();
 525         return err;
 526 }
 527
 528 SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
 529 {
 530         int version;
 531         struct ipc_namespace *ns;
 532         struct msqid64_ds msqid64;
 533         int err;
 534
 535         if (msqid < 0 || cmd < 0)
 536                 return -EINVAL;
 537
 538         version = ipc_parse_version(&cmd);
 539         ns = current->nsproxy->ipc_ns;
 540
 541         switch (cmd) {
 542         case IPC_INFO:
 543         case MSG_INFO: {
 544                 struct msginfo msginfo;
 545                 err = msgctl_info(ns, msqid, cmd, &msginfo);
 546                 if (err < 0)
 547                         return err;
 548                 if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
 549                         err = -EFAULT;
 550                 return err;
 551         }
 552         case MSG_STAT:  /* msqid is an index rather than a msg queue id */
 553         case IPC_STAT:
 554                 err = msgctl_stat(ns, msqid, cmd, &msqid64);
 555                 if (err < 0)
 556                         return err;
 557                 if (copy_msqid_to_user(buf, &msqid64, version))
 558                         err = -EFAULT;
 559                 return err;
 560         case IPC_SET:
 561                 if (copy_msqid_from_user(&msqid64, buf, version))
 562                         return -EFAULT;
 563                 /* fallthru */
 564         case IPC_RMID:
 565                 return msgctl_down(ns, msqid, cmd, &msqid64);
 566         default:
 567                 return  -EINVAL;
 568         }
 569 }
 570
 571 #ifdef CONFIG_COMPAT
 572
 573 struct compat_msqid_ds {
 574         struct compat_ipc_perm msg_perm;
 575         compat_uptr_t msg_first;
 576         compat_uptr_t msg_last;
 577         compat_time_t msg_stime;
 578         compat_time_t msg_rtime;
 579         compat_time_t msg_ctime;
 580         compat_ulong_t msg_lcbytes;
 581         compat_ulong_t msg_lqbytes;
 582         unsigned short msg_cbytes;
 583         unsigned short msg_qnum;
 584         unsigned short msg_qbytes;
 585         compat_ipc_pid_t msg_lspid;
 586         compat_ipc_pid_t msg_lrpid;
 587 };
 588
 589 static int copy_compat_msqid_from_user(struct msqid64_ds *out, void __user *buf,
 590                                         int version)
 591 {
 592         memset(out, 0, sizeof(*out));
 593         if (version == IPC_64) {
 594                 struct compat_msqid64_ds *p = buf;
 595                 if (get_compat_ipc64_perm(&out->msg_perm, &p->msg_perm))
 596                         return -EFAULT;
 597                 if (get_user(out->msg_qbytes, &p->msg_qbytes))
 598                         return -EFAULT;
 599         } else {
 600                 struct compat_msqid_ds *p = buf;
 601                 if (get_compat_ipc_perm(&out->msg_perm, &p->msg_perm))
 602                         return -EFAULT;
 603                 if (get_user(out->msg_qbytes, &p->msg_qbytes))
 604                         return -EFAULT;
 605         }
 606         return 0;
 607 }
 608
 609 static int copy_compat_msqid_to_user(void __user *buf, struct msqid64_ds *in,
 610                                         int version)
 611 {
 612         if (version == IPC_64) {
 613                 struct compat_msqid64_ds v;
 614                 memset(&v, 0, sizeof(v));
 615                 to_compat_ipc64_perm(&v.msg_perm, &in->msg_perm);
 616                 v.msg_stime = in->msg_stime;
 617                 v.msg_rtime = in->msg_rtime;
 618                 v.msg_ctime = in->msg_ctime;
 619                 v.msg_cbytes = in->msg_cbytes;
 620                 v.msg_qnum = in->msg_qnum;
 621                 v.msg_qbytes = in->msg_qbytes;
 622                 v.msg_lspid = in->msg_lspid;
 623                 v.msg_lrpid = in->msg_lrpid;
 624                 return copy_to_user(buf, &v, sizeof(v));
 625         } else {
 626                 struct compat_msqid_ds v;
 627                 memset(&v, 0, sizeof(v));
 628                 to_compat_ipc_perm(&v.msg_perm, &in->msg_perm);
 629                 v.msg_stime = in->msg_stime;
 630                 v.msg_rtime = in->msg_rtime;
 631                 v.msg_ctime = in->msg_ctime;
 632                 v.msg_cbytes = in->msg_cbytes;
 633                 v.msg_qnum = in->msg_qnum;
 634                 v.msg_qbytes = in->msg_qbytes;
 635                 v.msg_lspid = in->msg_lspid;
 636                 v.msg_lrpid = in->msg_lrpid;
 637                 return copy_to_user(buf, &v, sizeof(v));
 638         }
 639 }
 640
 641 COMPAT_SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, void __user *, uptr)
 642 {
 643         struct ipc_namespace *ns;
 644         int err;
 645         struct msqid64_ds msqid64;
 646         int version = compat_ipc_parse_version(&cmd);
 647
 648         ns = current->nsproxy->ipc_ns;
 649
 650         if (msqid < 0 || cmd < 0)
 651                 return -EINVAL;
 652
 653         switch (cmd & (~IPC_64)) {
 654         case IPC_INFO:
 655         case MSG_INFO: {
 656                 struct msginfo msginfo;
 657                 err = msgctl_info(ns, msqid, cmd, &msginfo);
 658                 if (err < 0)
 659                         return err;
 660                 if (copy_to_user(uptr, &msginfo, sizeof(struct msginfo)))
 661                         err = -EFAULT;
 662                 return err;
 663         }
 664         case IPC_STAT:
 665         case MSG_STAT:
 666                 err = msgctl_stat(ns, msqid, cmd, &msqid64);
 667                 if (err < 0)
 668                         return err;
 669                 if (copy_compat_msqid_to_user(uptr, &msqid64, version))
 670                         err = -EFAULT;
 671                 return err;
 672         case IPC_SET:
 673                 if (copy_compat_msqid_from_user(&msqid64, uptr, version))
 674                         return -EFAULT;
 675                 /* fallthru */
 676         case IPC_RMID:
 677                 return msgctl_down(ns, msqid, cmd, &msqid64);
 678         default:
 679                 return -EINVAL;
 680         }
 681 }
 682 #endif
 683
 684 static int testmsg(struct msg_msg *msg, long type, int mode)
 685 {
 686         switch (mode) {
 687         case SEARCH_ANY:
 688         case SEARCH_NUMBER:
 689                 return 1;
 690         case SEARCH_LESSEQUAL:
 691                 if (msg->m_type <= type)
 692                         return 1;
 693                 break;
 694         case SEARCH_EQUAL:
 695                 if (msg->m_type == type)
 696                         return 1;
 697                 break;
 698         case SEARCH_NOTEQUAL:
 699                 if (msg->m_type != type)
 700                         return 1;
 701                 break;
 702         }
 703         return 0;
 704 }
 705
 706 static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg,
 707                                  struct wake_q_head *wake_q)
 708 {
 709         struct msg_receiver *msr, *t;
 710
 711         list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
 712                 if (testmsg(msg, msr->r_msgtype, msr->r_mode) &&
 713                     !security_msg_queue_msgrcv(msq, msg, msr->r_tsk,
 714                                                msr->r_msgtype, msr->r_mode)) {
 715
 716                         list_del(&msr->r_list);
 717                         if (msr->r_maxsize < msg->m_ts) {
 718                                 wake_q_add(wake_q, msr->r_tsk);
 719                                 WRITE_ONCE(msr->r_msg, ERR_PTR(-E2BIG));
 720                         } else {
 721                                 msq->q_lrpid = task_pid_vnr(msr->r_tsk);
 722                                 msq->q_rtime = get_seconds();
 723
 724                                 wake_q_add(wake_q, msr->r_tsk);
 725                                 WRITE_ONCE(msr->r_msg, msg);
 726                                 return 1;
 727                         }
 728                 }
 729         }
 730
 731         return 0;
 732 }
 733
 734 static long do_msgsnd(int msqid, long mtype, void __user *mtext,
 735                 size_t msgsz, int msgflg)
 736 {
 737         struct msg_queue *msq;
 738         struct msg_msg *msg;
 739         int err;
 740         struct ipc_namespace *ns;
 741         DEFINE_WAKE_Q(wake_q);
 742
 743         ns = current->nsproxy->ipc_ns;
 744
 745         if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0)
 746                 return -EINVAL;
 747         if (mtype < 1)
 748                 return -EINVAL;
 749
 750         msg = load_msg(mtext, msgsz);
 751         if (IS_ERR(msg))
 752                 return PTR_ERR(msg);
 753
 754         msg->m_type = mtype;
 755         msg->m_ts = msgsz;
 756
 757         rcu_read_lock();
 758         msq = msq_obtain_object_check(ns, msqid);
 759         if (IS_ERR(msq)) {
 760                 err = PTR_ERR(msq);
 761                 goto out_unlock1;
 762         }
 763
 764         ipc_lock_object(&msq->q_perm);
 765
 766         for (;;) {
 767                 struct msg_sender s;
 768
 769                 err = -EACCES;
 770                 if (ipcperms(ns, &msq->q_perm, S_IWUGO))
 771                         goto out_unlock0;
 772
 773                 /* raced with RMID? */
 774                 if (!ipc_valid_object(&msq->q_perm)) {
 775                         err = -EIDRM;
 776                         goto out_unlock0;
 777                 }
 778
 779                 err = security_msg_queue_msgsnd(msq, msg, msgflg);
 780                 if (err)
 781                         goto out_unlock0;
 782
 783                 if (msg_fits_inqueue(msq, msgsz))
 784                         break;
 785
 786                 /* queue full, wait: */
 787                 if (msgflg & IPC_NOWAIT) {
 788                         err = -EAGAIN;
 789                         goto out_unlock0;
 790                 }
 791
 792                 /* enqueue the sender and prepare to block */
 793                 ss_add(msq, &s, msgsz);
 794
 795                 if (!ipc_rcu_getref(&msq->q_perm)) {
 796                         err = -EIDRM;
 797                         goto out_unlock0;
 798                 }
 799
 800                 ipc_unlock_object(&msq->q_perm);
 801                 rcu_read_unlock();
 802                 schedule();
 803
 804                 rcu_read_lock();
 805                 ipc_lock_object(&msq->q_perm);
 806
 807                 ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
 808                 /* raced with RMID? */
 809                 if (!ipc_valid_object(&msq->q_perm)) {
 810                         err = -EIDRM;
 811                         goto out_unlock0;
 812                 }
 813                 ss_del(&s);
 814
 815                 if (signal_pending(current)) {
 816                         err = -ERESTARTNOHAND;
 817                         goto out_unlock0;
 818                 }
 819
 820         }
 821
 822         msq->q_lspid = task_tgid_vnr(current);
 823         msq->q_stime = get_seconds();
 824
 825         if (!pipelined_send(msq, msg, &wake_q)) {
 826                 /* no one is waiting for this message, enqueue it */
 827                 list_add_tail(&msg->m_list, &msq->q_messages);
 828                 msq->q_cbytes += msgsz;
 829                 msq->q_qnum++;
 830                 atomic_add(msgsz, &ns->msg_bytes);
 831                 atomic_inc(&ns->msg_hdrs);
 832         }
 833
 834         err = 0;
 835         msg = NULL;
 836
 837 out_unlock0:
 838         ipc_unlock_object(&msq->q_perm);
 839         wake_up_q(&wake_q);
 840 out_unlock1:
 841         rcu_read_unlock();
 842         if (msg != NULL)
 843                 free_msg(msg);
 844         return err;
 845 }
 846
 847 SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
 848                 int, msgflg)
 849 {
 850         long mtype;
 851
 852         if (get_user(mtype, &msgp->mtype))
 853                 return -EFAULT;
 854         return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg);
 855 }
 856
 857 #ifdef CONFIG_COMPAT
 858
 859 struct compat_msgbuf {
 860         compat_long_t mtype;
 861         char mtext[1];
 862 };
 863
 864 COMPAT_SYSCALL_DEFINE4(msgsnd, int, msqid, compat_uptr_t, msgp,
 865                        compat_ssize_t, msgsz, int, msgflg)
 866 {
 867         struct compat_msgbuf __user *up = compat_ptr(msgp);
 868         compat_long_t mtype;
 869
 870         if (get_user(mtype, &up->mtype))
 871                 return -EFAULT;
 872         return do_msgsnd(msqid, mtype, up->mtext, (ssize_t)msgsz, msgflg);
 873 }
 874 #endif
 875
 876 static inline int convert_mode(long *msgtyp, int msgflg)
 877 {
 878         if (msgflg & MSG_COPY)
 879                 return SEARCH_NUMBER;
 880         /*
 881          *  find message of correct type.
 882          *  msgtyp = 0 => get first.
 883          *  msgtyp > 0 => get first message of matching type.
 884          *  msgtyp < 0 => get message with least type must be < abs(msgtype).
 885          */
 886         if (*msgtyp == 0)
 887                 return SEARCH_ANY;
 888         if (*msgtyp < 0) {
 889                 if (*msgtyp == LONG_MIN) /* -LONG_MIN is undefined */
 890                         *msgtyp = LONG_MAX;
 891                 else
 892                         *msgtyp = -*msgtyp;
 893                 return SEARCH_LESSEQUAL;
 894         }
 895         if (msgflg & MSG_EXCEPT)
 896                 return SEARCH_NOTEQUAL;
 897         return SEARCH_EQUAL;
 898 }
 899
 900 static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
 901 {
 902         struct msgbuf __user *msgp = dest;
 903         size_t msgsz;
 904
 905         if (put_user(msg->m_type, &msgp->mtype))
 906                 return -EFAULT;
 907
 908         msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
 909         if (store_msg(msgp->mtext, msg, msgsz))
 910                 return -EFAULT;
 911         return msgsz;
 912 }
 913
 914 #ifdef CONFIG_CHECKPOINT_RESTORE
 915 /*
 916  * This function creates new kernel message structure, large enough to store
 917  * bufsz message bytes.
 918  */
 919 static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
 920 {
 921         struct msg_msg *copy;
 922
 923         /*
 924          * Create dummy message to copy real message to.
 925          */
 926         copy = load_msg(buf, bufsz);
 927         if (!IS_ERR(copy))
 928                 copy->m_ts = bufsz;
 929         return copy;
 930 }
 931
 932 static inline void free_copy(struct msg_msg *copy)
 933 {
 934         if (copy)
 935                 free_msg(copy);
 936 }
 937 #else
 938 static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
 939 {
 940         return ERR_PTR(-ENOSYS);
 941 }
 942
 943 static inline void free_copy(struct msg_msg *copy)
 944 {
 945 }
 946 #endif
 947
 948 static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode)
 949 {
 950         struct msg_msg *msg, *found = NULL;
 951         long count = 0;
 952
 953         list_for_each_entry(msg, &msq->q_messages, m_list) {
 954                 if (testmsg(msg, *msgtyp, mode) &&
 955                     !security_msg_queue_msgrcv(msq, msg, current,
 956                                                *msgtyp, mode)) {
 957                         if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) {
 958                                 *msgtyp = msg->m_type - 1;
 959                                 found = msg;
 960                         } else if (mode == SEARCH_NUMBER) {
 961                                 if (*msgtyp == count)
 962                                         return msg;
 963                         } else
 964                                 return msg;
 965                         count++;
 966                 }
 967         }
 968
 969         return found ?: ERR_PTR(-EAGAIN);
 970 }
 971
 972 static long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg,
 973                long (*msg_handler)(void __user *, struct msg_msg *, size_t))
 974 {
 975         int mode;
 976         struct msg_queue *msq;
 977         struct ipc_namespace *ns;
 978         struct msg_msg *msg, *copy = NULL;
 979         DEFINE_WAKE_Q(wake_q);
 980
 981         ns = current->nsproxy->ipc_ns;
 982
 983         if (msqid < 0 || (long) bufsz < 0)
 984                 return -EINVAL;
 985
 986         if (msgflg & MSG_COPY) {
 987                 if ((msgflg & MSG_EXCEPT) || !(msgflg & IPC_NOWAIT))
 988                         return -EINVAL;
 989                 copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax));
 990                 if (IS_ERR(copy))
 991                         return PTR_ERR(copy);
 992         }
 993         mode = convert_mode(&msgtyp, msgflg);
 994
 995         rcu_read_lock();
 996         msq = msq_obtain_object_check(ns, msqid);
 997         if (IS_ERR(msq)) {
 998                 rcu_read_unlock();
 999                 free_copy(copy);
1000                 return PTR_ERR(msq);
1001         }
1002
1003         for (;;) {
1004                 struct msg_receiver msr_d;
1005
1006                 msg = ERR_PTR(-EACCES);
1007                 if (ipcperms(ns, &msq->q_perm, S_IRUGO))
1008                         goto out_unlock1;
1009
1010                 ipc_lock_object(&msq->q_perm);
1011
1012                 /* raced with RMID? */
1013                 if (!ipc_valid_object(&msq->q_perm)) {
1014                         msg = ERR_PTR(-EIDRM);
1015                         goto out_unlock0;
1016                 }
1017
1018                 msg = find_msg(msq, &msgtyp, mode);
1019                 if (!IS_ERR(msg)) {
1020                         /*
1021                          * Found a suitable message.
1022                          * Unlink it from the queue.
1023                          */
1024                         if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
1025                                 msg = ERR_PTR(-E2BIG);
1026                                 goto out_unlock0;
1027                         }
1028                         /*
1029                          * If we are copying, then do not unlink message and do
1030                          * not update queue parameters.
1031                          */
1032                         if (msgflg & MSG_COPY) {
1033                                 msg = copy_msg(msg, copy);
1034                                 goto out_unlock0;
1035                         }
1036
1037                         list_del(&msg->m_list);
1038                         msq->q_qnum--;
1039                         msq->q_rtime = get_seconds();
1040                         msq->q_lrpid = task_tgid_vnr(current);
1041                         msq->q_cbytes -= msg->m_ts;
1042                         atomic_sub(msg->m_ts, &ns->msg_bytes);
1043                         atomic_dec(&ns->msg_hdrs);
1044                         ss_wakeup(msq, &wake_q, false);
1045
1046                         goto out_unlock0;
1047                 }
1048
1049                 /* No message waiting. Wait for a message */
1050                 if (msgflg & IPC_NOWAIT) {
1051                         msg = ERR_PTR(-ENOMSG);
1052                         goto out_unlock0;
1053                 }
1054
1055                 list_add_tail(&msr_d.r_list, &msq->q_receivers);
1056                 msr_d.r_tsk = current;
1057                 msr_d.r_msgtype = msgtyp;
1058                 msr_d.r_mode = mode;
1059                 if (msgflg & MSG_NOERROR)
1060                         msr_d.r_maxsize = INT_MAX;
1061                 else
1062                         msr_d.r_maxsize = bufsz;
1063                 msr_d.r_msg = ERR_PTR(-EAGAIN);
1064                 __set_current_state(TASK_INTERRUPTIBLE);
1065
1066                 ipc_unlock_object(&msq->q_perm);
1067                 rcu_read_unlock();
1068                 schedule();
1069
1070                 /*
1071                  * Lockless receive, part 1:
1072                  * We don't hold a reference to the queue and getting a
1073                  * reference would defeat the idea of a lockless operation,
1074                  * thus the code relies on rcu to guarantee the existence of
1075                  * msq:
1076                  * Prior to destruction, expunge_all(-EIRDM) changes r_msg.
1077                  * Thus if r_msg is -EAGAIN, then the queue not yet destroyed.
1078                  */
1079                 rcu_read_lock();
1080
1081                 /*
1082                  * Lockless receive, part 2:
1083                  * The work in pipelined_send() and expunge_all():
1084                  * - Set pointer to message
1085                  * - Queue the receiver task for later wakeup
1086                  * - Wake up the process after the lock is dropped.
1087                  *
1088                  * Should the process wake up before this wakeup (due to a
1089                  * signal) it will either see the message and continue ...
1090                  */
1091                 msg = READ_ONCE(msr_d.r_msg);
1092                 if (msg != ERR_PTR(-EAGAIN))
1093                         goto out_unlock1;
1094
1095                  /*
1096                   * ... or see -EAGAIN, acquire the lock to check the message
1097                   * again.
1098                   */
1099                 ipc_lock_object(&msq->q_perm);
1100
1101                 msg = msr_d.r_msg;
1102                 if (msg != ERR_PTR(-EAGAIN))
1103                         goto out_unlock0;
1104
1105                 list_del(&msr_d.r_list);
1106                 if (signal_pending(current)) {
1107                         msg = ERR_PTR(-ERESTARTNOHAND);
1108                         goto out_unlock0;
1109                 }
1110
1111                 ipc_unlock_object(&msq->q_perm);
1112         }
1113
1114 out_unlock0:
1115         ipc_unlock_object(&msq->q_perm);
1116         wake_up_q(&wake_q);
1117 out_unlock1:
1118         rcu_read_unlock();
1119         if (IS_ERR(msg)) {
1120                 free_copy(copy);
1121                 return PTR_ERR(msg);
1122         }
1123
1124         bufsz = msg_handler(buf, msg, bufsz);
1125         free_msg(msg);
1126
1127         return bufsz;
1128 }
1129
1130 SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
1131                 long, msgtyp, int, msgflg)
1132 {
1133         return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill);
1134 }
1135
1136 #ifdef CONFIG_COMPAT
1137 static long compat_do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
1138 {
1139         struct compat_msgbuf __user *msgp = dest;
1140         size_t msgsz;
1141
1142         if (put_user(msg->m_type, &msgp->mtype))
1143                 return -EFAULT;
1144
1145         msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
1146         if (store_msg(msgp->mtext, msg, msgsz))
1147                 return -EFAULT;
1148         return msgsz;
1149 }
1150
1151 COMPAT_SYSCALL_DEFINE5(msgrcv, int, msqid, compat_uptr_t, msgp,
1152                        compat_ssize_t, msgsz, compat_long_t, msgtyp, int, msgflg)
1153 {
1154         return do_msgrcv(msqid, compat_ptr(msgp), (ssize_t)msgsz, (long)msgtyp,
1155                          msgflg, compat_do_msg_fill);
1156 }
1157 #endif
1158
1159 int msg_init_ns(struct ipc_namespace *ns)
1160 {
1161         ns->msg_ctlmax = MSGMAX;
1162         ns->msg_ctlmnb = MSGMNB;
1163         ns->msg_ctlmni = MSGMNI;
1164
1165         atomic_set(&ns->msg_bytes, 0);
1166         atomic_set(&ns->msg_hdrs, 0);
1167         return ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
1168 }
1169
1170 #ifdef CONFIG_IPC_NS
1171 void msg_exit_ns(struct ipc_namespace *ns)
1172 {
1173         free_ipcs(ns, &msg_ids(ns), freeque);
1174         idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr);
1175         rhashtable_destroy(&ns->ids[IPC_MSG_IDS].key_ht);
1176 }
1177 #endif
1178
1179 #ifdef CONFIG_PROC_FS
1180 static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
1181 {
1182         struct user_namespace *user_ns = seq_user_ns(s);
1183         struct kern_ipc_perm *ipcp = it;
1184         struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
1185
1186         seq_printf(s,
1187                    "%10d %10d  %4o  %10lu %10lu %5u %5u %5u %5u %5u %5u %10llu %10llu %10llu\n",
1188                    msq->q_perm.key,
1189                    msq->q_perm.id,
1190                    msq->q_perm.mode,
1191                    msq->q_cbytes,
1192                    msq->q_qnum,
1193                    msq->q_lspid,
1194                    msq->q_lrpid,
1195                    from_kuid_munged(user_ns, msq->q_perm.uid),
1196                    from_kgid_munged(user_ns, msq->q_perm.gid),
1197                    from_kuid_munged(user_ns, msq->q_perm.cuid),
1198                    from_kgid_munged(user_ns, msq->q_perm.cgid),
1199                    msq->q_stime,
1200                    msq->q_rtime,
1201                    msq->q_ctime);
1202
1203         return 0;
1204 }
1205 #endif
1206
1207 int __init msg_init(void)
1208 {
1209         const int err = msg_init_ns(&init_ipc_ns);
1210
1211         ipc_init_proc_interface("sysvipc/msg",
1212                                 "       key      msqid perms      cbytes       qnum lspid lrpid   uid   gid  cuid  cgid      stime      rtime      ctime\n",
1213                                 IPC_MSG_IDS, sysvipc_msg_proc_show);
1214         return err;
1215 }