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 long ksys_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 SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
 284 {
 285         return ksys_msgget(key, msgflg);
 286 }
 287
 288 static inline unsigned long
 289 copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
 290 {
 291         switch (version) {
 292         case IPC_64:
 293                 return copy_to_user(buf, in, sizeof(*in));
 294         case IPC_OLD:
 295         {
 296                 struct msqid_ds out;
 297
 298                 memset(&out, 0, sizeof(out));
 299
 300                 ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
 301
 302                 out.msg_stime           = in->msg_stime;
 303                 out.msg_rtime           = in->msg_rtime;
 304                 out.msg_ctime           = in->msg_ctime;
 305
 306                 if (in->msg_cbytes > USHRT_MAX)
 307                         out.msg_cbytes  = USHRT_MAX;
 308                 else
 309                         out.msg_cbytes  = in->msg_cbytes;
 310                 out.msg_lcbytes         = in->msg_cbytes;
 311
 312                 if (in->msg_qnum > USHRT_MAX)
 313                         out.msg_qnum    = USHRT_MAX;
 314                 else
 315                         out.msg_qnum    = in->msg_qnum;
 316
 317                 if (in->msg_qbytes > USHRT_MAX)
 318                         out.msg_qbytes  = USHRT_MAX;
 319                 else
 320                         out.msg_qbytes  = in->msg_qbytes;
 321                 out.msg_lqbytes         = in->msg_qbytes;
 322
 323                 out.msg_lspid           = in->msg_lspid;
 324                 out.msg_lrpid           = in->msg_lrpid;
 325
 326                 return copy_to_user(buf, &out, sizeof(out));
 327         }
 328         default:
 329                 return -EINVAL;
 330         }
 331 }
 332
 333 static inline unsigned long
 334 copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version)
 335 {
 336         switch (version) {
 337         case IPC_64:
 338                 if (copy_from_user(out, buf, sizeof(*out)))
 339                         return -EFAULT;
 340                 return 0;
 341         case IPC_OLD:
 342         {
 343                 struct msqid_ds tbuf_old;
 344
 345                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 346                         return -EFAULT;
 347
 348                 out->msg_perm.uid       = tbuf_old.msg_perm.uid;
 349                 out->msg_perm.gid       = tbuf_old.msg_perm.gid;
 350                 out->msg_perm.mode      = tbuf_old.msg_perm.mode;
 351
 352                 if (tbuf_old.msg_qbytes == 0)
 353                         out->msg_qbytes = tbuf_old.msg_lqbytes;
 354                 else
 355                         out->msg_qbytes = tbuf_old.msg_qbytes;
 356
 357                 return 0;
 358         }
 359         default:
 360                 return -EINVAL;
 361         }
 362 }
 363
 364 /*
 365  * This function handles some msgctl commands which require the rwsem
 366  * to be held in write mode.
 367  * NOTE: no locks must be held, the rwsem is taken inside this function.
 368  */
 369 static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
 370                         struct msqid64_ds *msqid64)
 371 {
 372         struct kern_ipc_perm *ipcp;
 373         struct msg_queue *msq;
 374         int err;
 375
 376         down_write(&msg_ids(ns).rwsem);
 377         rcu_read_lock();
 378
 379         ipcp = ipcctl_pre_down_nolock(ns, &msg_ids(ns), msqid, cmd,
 380                                       &msqid64->msg_perm, msqid64->msg_qbytes);
 381         if (IS_ERR(ipcp)) {
 382                 err = PTR_ERR(ipcp);
 383                 goto out_unlock1;
 384         }
 385
 386         msq = container_of(ipcp, struct msg_queue, q_perm);
 387
 388         err = security_msg_queue_msgctl(msq, cmd);
 389         if (err)
 390                 goto out_unlock1;
 391
 392         switch (cmd) {
 393         case IPC_RMID:
 394                 ipc_lock_object(&msq->q_perm);
 395                 /* freeque unlocks the ipc object and rcu */
 396                 freeque(ns, ipcp);
 397                 goto out_up;
 398         case IPC_SET:
 399         {
 400                 DEFINE_WAKE_Q(wake_q);
 401
 402                 if (msqid64->msg_qbytes > ns->msg_ctlmnb &&
 403                     !capable(CAP_SYS_RESOURCE)) {
 404                         err = -EPERM;
 405                         goto out_unlock1;
 406                 }
 407
 408                 ipc_lock_object(&msq->q_perm);
 409                 err = ipc_update_perm(&msqid64->msg_perm, ipcp);
 410                 if (err)
 411                         goto out_unlock0;
 412
 413                 msq->q_qbytes = msqid64->msg_qbytes;
 414
 415                 msq->q_ctime = ktime_get_real_seconds();
 416                 /*
 417                  * Sleeping receivers might be excluded by
 418                  * stricter permissions.
 419                  */
 420                 expunge_all(msq, -EAGAIN, &wake_q);
 421                 /*
 422                  * Sleeping senders might be able to send
 423                  * due to a larger queue size.
 424                  */
 425                 ss_wakeup(msq, &wake_q, false);
 426                 ipc_unlock_object(&msq->q_perm);
 427                 wake_up_q(&wake_q);
 428
 429                 goto out_unlock1;
 430         }
 431         default:
 432                 err = -EINVAL;
 433                 goto out_unlock1;
 434         }
 435
 436 out_unlock0:
 437         ipc_unlock_object(&msq->q_perm);
 438 out_unlock1:
 439         rcu_read_unlock();
 440 out_up:
 441         up_write(&msg_ids(ns).rwsem);
 442         return err;
 443 }
 444
 445 static int msgctl_info(struct ipc_namespace *ns, int msqid,
 446                          int cmd, struct msginfo *msginfo)
 447 {
 448         int err;
 449         int max_id;
 450
 451         /*
 452          * We must not return kernel stack data.
 453          * due to padding, it's not enough
 454          * to set all member fields.
 455          */
 456         err = security_msg_queue_msgctl(NULL, cmd);
 457         if (err)
 458                 return err;
 459
 460         memset(msginfo, 0, sizeof(*msginfo));
 461         msginfo->msgmni = ns->msg_ctlmni;
 462         msginfo->msgmax = ns->msg_ctlmax;
 463         msginfo->msgmnb = ns->msg_ctlmnb;
 464         msginfo->msgssz = MSGSSZ;
 465         msginfo->msgseg = MSGSEG;
 466         down_read(&msg_ids(ns).rwsem);
 467         if (cmd == MSG_INFO) {
 468                 msginfo->msgpool = msg_ids(ns).in_use;
 469                 msginfo->msgmap = atomic_read(&ns->msg_hdrs);
 470                 msginfo->msgtql = atomic_read(&ns->msg_bytes);
 471         } else {
 472                 msginfo->msgmap = MSGMAP;
 473                 msginfo->msgpool = MSGPOOL;
 474                 msginfo->msgtql = MSGTQL;
 475         }
 476         max_id = ipc_get_maxid(&msg_ids(ns));
 477         up_read(&msg_ids(ns).rwsem);
 478         return (max_id < 0) ? 0 : max_id;
 479 }
 480
 481 static int msgctl_stat(struct ipc_namespace *ns, int msqid,
 482                          int cmd, struct msqid64_ds *p)
 483 {
 484         struct msg_queue *msq;
 485         int id = 0;
 486         int err;
 487
 488         memset(p, 0, sizeof(*p));
 489
 490         rcu_read_lock();
 491         if (cmd == MSG_STAT) {
 492                 msq = msq_obtain_object(ns, msqid);
 493                 if (IS_ERR(msq)) {
 494                         err = PTR_ERR(msq);
 495                         goto out_unlock;
 496                 }
 497                 id = msq->q_perm.id;
 498         } else {
 499                 msq = msq_obtain_object_check(ns, msqid);
 500                 if (IS_ERR(msq)) {
 501                         err = PTR_ERR(msq);
 502                         goto out_unlock;
 503                 }
 504         }
 505
 506         err = -EACCES;
 507         if (ipcperms(ns, &msq->q_perm, S_IRUGO))
 508                 goto out_unlock;
 509
 510         err = security_msg_queue_msgctl(msq, cmd);
 511         if (err)
 512                 goto out_unlock;
 513
 514         ipc_lock_object(&msq->q_perm);
 515
 516         if (!ipc_valid_object(&msq->q_perm)) {
 517                 ipc_unlock_object(&msq->q_perm);
 518                 err = -EIDRM;
 519                 goto out_unlock;
 520         }
 521
 522         kernel_to_ipc64_perm(&msq->q_perm, &p->msg_perm);
 523         p->msg_stime  = msq->q_stime;
 524         p->msg_rtime  = msq->q_rtime;
 525         p->msg_ctime  = msq->q_ctime;
 526         p->msg_cbytes = msq->q_cbytes;
 527         p->msg_qnum   = msq->q_qnum;
 528         p->msg_qbytes = msq->q_qbytes;
 529         p->msg_lspid  = msq->q_lspid;
 530         p->msg_lrpid  = msq->q_lrpid;
 531
 532         ipc_unlock_object(&msq->q_perm);
 533         rcu_read_unlock();
 534         return id;
 535
 536 out_unlock:
 537         rcu_read_unlock();
 538         return err;
 539 }
 540
 541 long ksys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf)
 542 {
 543         int version;
 544         struct ipc_namespace *ns;
 545         struct msqid64_ds msqid64;
 546         int err;
 547
 548         if (msqid < 0 || cmd < 0)
 549                 return -EINVAL;
 550
 551         version = ipc_parse_version(&cmd);
 552         ns = current->nsproxy->ipc_ns;
 553
 554         switch (cmd) {
 555         case IPC_INFO:
 556         case MSG_INFO: {
 557                 struct msginfo msginfo;
 558                 err = msgctl_info(ns, msqid, cmd, &msginfo);
 559                 if (err < 0)
 560                         return err;
 561                 if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
 562                         err = -EFAULT;
 563                 return err;
 564         }
 565         case MSG_STAT:  /* msqid is an index rather than a msg queue id */
 566         case IPC_STAT:
 567                 err = msgctl_stat(ns, msqid, cmd, &msqid64);
 568                 if (err < 0)
 569                         return err;
 570                 if (copy_msqid_to_user(buf, &msqid64, version))
 571                         err = -EFAULT;
 572                 return err;
 573         case IPC_SET:
 574                 if (copy_msqid_from_user(&msqid64, buf, version))
 575                         return -EFAULT;
 576                 /* fallthru */
 577         case IPC_RMID:
 578                 return msgctl_down(ns, msqid, cmd, &msqid64);
 579         default:
 580                 return  -EINVAL;
 581         }
 582 }
 583
 584 SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
 585 {
 586         return ksys_msgctl(msqid, cmd, buf);
 587 }
 588
 589 #ifdef CONFIG_COMPAT
 590
 591 struct compat_msqid_ds {
 592         struct compat_ipc_perm msg_perm;
 593         compat_uptr_t msg_first;
 594         compat_uptr_t msg_last;
 595         compat_time_t msg_stime;
 596         compat_time_t msg_rtime;
 597         compat_time_t msg_ctime;
 598         compat_ulong_t msg_lcbytes;
 599         compat_ulong_t msg_lqbytes;
 600         unsigned short msg_cbytes;
 601         unsigned short msg_qnum;
 602         unsigned short msg_qbytes;
 603         compat_ipc_pid_t msg_lspid;
 604         compat_ipc_pid_t msg_lrpid;
 605 };
 606
 607 static int copy_compat_msqid_from_user(struct msqid64_ds *out, void __user *buf,
 608                                         int version)
 609 {
 610         memset(out, 0, sizeof(*out));
 611         if (version == IPC_64) {
 612                 struct compat_msqid64_ds __user *p = buf;
 613                 if (get_compat_ipc64_perm(&out->msg_perm, &p->msg_perm))
 614                         return -EFAULT;
 615                 if (get_user(out->msg_qbytes, &p->msg_qbytes))
 616                         return -EFAULT;
 617         } else {
 618                 struct compat_msqid_ds __user *p = buf;
 619                 if (get_compat_ipc_perm(&out->msg_perm, &p->msg_perm))
 620                         return -EFAULT;
 621                 if (get_user(out->msg_qbytes, &p->msg_qbytes))
 622                         return -EFAULT;
 623         }
 624         return 0;
 625 }
 626
 627 static int copy_compat_msqid_to_user(void __user *buf, struct msqid64_ds *in,
 628                                         int version)
 629 {
 630         if (version == IPC_64) {
 631                 struct compat_msqid64_ds v;
 632                 memset(&v, 0, sizeof(v));
 633                 to_compat_ipc64_perm(&v.msg_perm, &in->msg_perm);
 634                 v.msg_stime = in->msg_stime;
 635                 v.msg_rtime = in->msg_rtime;
 636                 v.msg_ctime = in->msg_ctime;
 637                 v.msg_cbytes = in->msg_cbytes;
 638                 v.msg_qnum = in->msg_qnum;
 639                 v.msg_qbytes = in->msg_qbytes;
 640                 v.msg_lspid = in->msg_lspid;
 641                 v.msg_lrpid = in->msg_lrpid;
 642                 return copy_to_user(buf, &v, sizeof(v));
 643         } else {
 644                 struct compat_msqid_ds v;
 645                 memset(&v, 0, sizeof(v));
 646                 to_compat_ipc_perm(&v.msg_perm, &in->msg_perm);
 647                 v.msg_stime = in->msg_stime;
 648                 v.msg_rtime = in->msg_rtime;
 649                 v.msg_ctime = in->msg_ctime;
 650                 v.msg_cbytes = in->msg_cbytes;
 651                 v.msg_qnum = in->msg_qnum;
 652                 v.msg_qbytes = in->msg_qbytes;
 653                 v.msg_lspid = in->msg_lspid;
 654                 v.msg_lrpid = in->msg_lrpid;
 655                 return copy_to_user(buf, &v, sizeof(v));
 656         }
 657 }
 658
 659 long compat_ksys_msgctl(int msqid, int cmd, void __user *uptr)
 660 {
 661         struct ipc_namespace *ns;
 662         int err;
 663         struct msqid64_ds msqid64;
 664         int version = compat_ipc_parse_version(&cmd);
 665
 666         ns = current->nsproxy->ipc_ns;
 667
 668         if (msqid < 0 || cmd < 0)
 669                 return -EINVAL;
 670
 671         switch (cmd & (~IPC_64)) {
 672         case IPC_INFO:
 673         case MSG_INFO: {
 674                 struct msginfo msginfo;
 675                 err = msgctl_info(ns, msqid, cmd, &msginfo);
 676                 if (err < 0)
 677                         return err;
 678                 if (copy_to_user(uptr, &msginfo, sizeof(struct msginfo)))
 679                         err = -EFAULT;
 680                 return err;
 681         }
 682         case IPC_STAT:
 683         case MSG_STAT:
 684                 err = msgctl_stat(ns, msqid, cmd, &msqid64);
 685                 if (err < 0)
 686                         return err;
 687                 if (copy_compat_msqid_to_user(uptr, &msqid64, version))
 688                         err = -EFAULT;
 689                 return err;
 690         case IPC_SET:
 691                 if (copy_compat_msqid_from_user(&msqid64, uptr, version))
 692                         return -EFAULT;
 693                 /* fallthru */
 694         case IPC_RMID:
 695                 return msgctl_down(ns, msqid, cmd, &msqid64);
 696         default:
 697                 return -EINVAL;
 698         }
 699 }
 700
 701 COMPAT_SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, void __user *, uptr)
 702 {
 703         return compat_ksys_msgctl(msqid, cmd, uptr);
 704 }
 705 #endif
 706
 707 static int testmsg(struct msg_msg *msg, long type, int mode)
 708 {
 709         switch (mode) {
 710         case SEARCH_ANY:
 711         case SEARCH_NUMBER:
 712                 return 1;
 713         case SEARCH_LESSEQUAL:
 714                 if (msg->m_type <= type)
 715                         return 1;
 716                 break;
 717         case SEARCH_EQUAL:
 718                 if (msg->m_type == type)
 719                         return 1;
 720                 break;
 721         case SEARCH_NOTEQUAL:
 722                 if (msg->m_type != type)
 723                         return 1;
 724                 break;
 725         }
 726         return 0;
 727 }
 728
 729 static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg,
 730                                  struct wake_q_head *wake_q)
 731 {
 732         struct msg_receiver *msr, *t;
 733
 734         list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
 735                 if (testmsg(msg, msr->r_msgtype, msr->r_mode) &&
 736                     !security_msg_queue_msgrcv(msq, msg, msr->r_tsk,
 737                                                msr->r_msgtype, msr->r_mode)) {
 738
 739                         list_del(&msr->r_list);
 740                         if (msr->r_maxsize < msg->m_ts) {
 741                                 wake_q_add(wake_q, msr->r_tsk);
 742                                 WRITE_ONCE(msr->r_msg, ERR_PTR(-E2BIG));
 743                         } else {
 744                                 msq->q_lrpid = task_pid_vnr(msr->r_tsk);
 745                                 msq->q_rtime = get_seconds();
 746
 747                                 wake_q_add(wake_q, msr->r_tsk);
 748                                 WRITE_ONCE(msr->r_msg, msg);
 749                                 return 1;
 750                         }
 751                 }
 752         }
 753
 754         return 0;
 755 }
 756
 757 static long do_msgsnd(int msqid, long mtype, void __user *mtext,
 758                 size_t msgsz, int msgflg)
 759 {
 760         struct msg_queue *msq;
 761         struct msg_msg *msg;
 762         int err;
 763         struct ipc_namespace *ns;
 764         DEFINE_WAKE_Q(wake_q);
 765
 766         ns = current->nsproxy->ipc_ns;
 767
 768         if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0)
 769                 return -EINVAL;
 770         if (mtype < 1)
 771                 return -EINVAL;
 772
 773         msg = load_msg(mtext, msgsz);
 774         if (IS_ERR(msg))
 775                 return PTR_ERR(msg);
 776
 777         msg->m_type = mtype;
 778         msg->m_ts = msgsz;
 779
 780         rcu_read_lock();
 781         msq = msq_obtain_object_check(ns, msqid);
 782         if (IS_ERR(msq)) {
 783                 err = PTR_ERR(msq);
 784                 goto out_unlock1;
 785         }
 786
 787         ipc_lock_object(&msq->q_perm);
 788
 789         for (;;) {
 790                 struct msg_sender s;
 791
 792                 err = -EACCES;
 793                 if (ipcperms(ns, &msq->q_perm, S_IWUGO))
 794                         goto out_unlock0;
 795
 796                 /* raced with RMID? */
 797                 if (!ipc_valid_object(&msq->q_perm)) {
 798                         err = -EIDRM;
 799                         goto out_unlock0;
 800                 }
 801
 802                 err = security_msg_queue_msgsnd(msq, msg, msgflg);
 803                 if (err)
 804                         goto out_unlock0;
 805
 806                 if (msg_fits_inqueue(msq, msgsz))
 807                         break;
 808
 809                 /* queue full, wait: */
 810                 if (msgflg & IPC_NOWAIT) {
 811                         err = -EAGAIN;
 812                         goto out_unlock0;
 813                 }
 814
 815                 /* enqueue the sender and prepare to block */
 816                 ss_add(msq, &s, msgsz);
 817
 818                 if (!ipc_rcu_getref(&msq->q_perm)) {
 819                         err = -EIDRM;
 820                         goto out_unlock0;
 821                 }
 822
 823                 ipc_unlock_object(&msq->q_perm);
 824                 rcu_read_unlock();
 825                 schedule();
 826
 827                 rcu_read_lock();
 828                 ipc_lock_object(&msq->q_perm);
 829
 830                 ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
 831                 /* raced with RMID? */
 832                 if (!ipc_valid_object(&msq->q_perm)) {
 833                         err = -EIDRM;
 834                         goto out_unlock0;
 835                 }
 836                 ss_del(&s);
 837
 838                 if (signal_pending(current)) {
 839                         err = -ERESTARTNOHAND;
 840                         goto out_unlock0;
 841                 }
 842
 843         }
 844
 845         msq->q_lspid = task_tgid_vnr(current);
 846         msq->q_stime = get_seconds();
 847
 848         if (!pipelined_send(msq, msg, &wake_q)) {
 849                 /* no one is waiting for this message, enqueue it */
 850                 list_add_tail(&msg->m_list, &msq->q_messages);
 851                 msq->q_cbytes += msgsz;
 852                 msq->q_qnum++;
 853                 atomic_add(msgsz, &ns->msg_bytes);
 854                 atomic_inc(&ns->msg_hdrs);
 855         }
 856
 857         err = 0;
 858         msg = NULL;
 859
 860 out_unlock0:
 861         ipc_unlock_object(&msq->q_perm);
 862         wake_up_q(&wake_q);
 863 out_unlock1:
 864         rcu_read_unlock();
 865         if (msg != NULL)
 866                 free_msg(msg);
 867         return err;
 868 }
 869
 870 SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
 871                 int, msgflg)
 872 {
 873         long mtype;
 874
 875         if (get_user(mtype, &msgp->mtype))
 876                 return -EFAULT;
 877         return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg);
 878 }
 879
 880 #ifdef CONFIG_COMPAT
 881
 882 struct compat_msgbuf {
 883         compat_long_t mtype;
 884         char mtext[1];
 885 };
 886
 887 COMPAT_SYSCALL_DEFINE4(msgsnd, int, msqid, compat_uptr_t, msgp,
 888                        compat_ssize_t, msgsz, int, msgflg)
 889 {
 890         struct compat_msgbuf __user *up = compat_ptr(msgp);
 891         compat_long_t mtype;
 892
 893         if (get_user(mtype, &up->mtype))
 894                 return -EFAULT;
 895         return do_msgsnd(msqid, mtype, up->mtext, (ssize_t)msgsz, msgflg);
 896 }
 897 #endif
 898
 899 static inline int convert_mode(long *msgtyp, int msgflg)
 900 {
 901         if (msgflg & MSG_COPY)
 902                 return SEARCH_NUMBER;
 903         /*
 904          *  find message of correct type.
 905          *  msgtyp = 0 => get first.
 906          *  msgtyp > 0 => get first message of matching type.
 907          *  msgtyp < 0 => get message with least type must be < abs(msgtype).
 908          */
 909         if (*msgtyp == 0)
 910                 return SEARCH_ANY;
 911         if (*msgtyp < 0) {
 912                 if (*msgtyp == LONG_MIN) /* -LONG_MIN is undefined */
 913                         *msgtyp = LONG_MAX;
 914                 else
 915                         *msgtyp = -*msgtyp;
 916                 return SEARCH_LESSEQUAL;
 917         }
 918         if (msgflg & MSG_EXCEPT)
 919                 return SEARCH_NOTEQUAL;
 920         return SEARCH_EQUAL;
 921 }
 922
 923 static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
 924 {
 925         struct msgbuf __user *msgp = dest;
 926         size_t msgsz;
 927
 928         if (put_user(msg->m_type, &msgp->mtype))
 929                 return -EFAULT;
 930
 931         msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
 932         if (store_msg(msgp->mtext, msg, msgsz))
 933                 return -EFAULT;
 934         return msgsz;
 935 }
 936
 937 #ifdef CONFIG_CHECKPOINT_RESTORE
 938 /*
 939  * This function creates new kernel message structure, large enough to store
 940  * bufsz message bytes.
 941  */
 942 static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
 943 {
 944         struct msg_msg *copy;
 945
 946         /*
 947          * Create dummy message to copy real message to.
 948          */
 949         copy = load_msg(buf, bufsz);
 950         if (!IS_ERR(copy))
 951                 copy->m_ts = bufsz;
 952         return copy;
 953 }
 954
 955 static inline void free_copy(struct msg_msg *copy)
 956 {
 957         if (copy)
 958                 free_msg(copy);
 959 }
 960 #else
 961 static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
 962 {
 963         return ERR_PTR(-ENOSYS);
 964 }
 965
 966 static inline void free_copy(struct msg_msg *copy)
 967 {
 968 }
 969 #endif
 970
 971 static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode)
 972 {
 973         struct msg_msg *msg, *found = NULL;
 974         long count = 0;
 975
 976         list_for_each_entry(msg, &msq->q_messages, m_list) {
 977                 if (testmsg(msg, *msgtyp, mode) &&
 978                     !security_msg_queue_msgrcv(msq, msg, current,
 979                                                *msgtyp, mode)) {
 980                         if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) {
 981                                 *msgtyp = msg->m_type - 1;
 982                                 found = msg;
 983                         } else if (mode == SEARCH_NUMBER) {
 984                                 if (*msgtyp == count)
 985                                         return msg;
 986                         } else
 987                                 return msg;
 988                         count++;
 989                 }
 990         }
 991
 992         return found ?: ERR_PTR(-EAGAIN);
 993 }
 994
 995 static long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg,
 996                long (*msg_handler)(void __user *, struct msg_msg *, size_t))
 997 {
 998         int mode;
 999         struct msg_queue *msq;
1000         struct ipc_namespace *ns;
1001         struct msg_msg *msg, *copy = NULL;
1002         DEFINE_WAKE_Q(wake_q);
1003
1004         ns = current->nsproxy->ipc_ns;
1005
1006         if (msqid < 0 || (long) bufsz < 0)
1007                 return -EINVAL;
1008
1009         if (msgflg & MSG_COPY) {
1010                 if ((msgflg & MSG_EXCEPT) || !(msgflg & IPC_NOWAIT))
1011                         return -EINVAL;
1012                 copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax));
1013                 if (IS_ERR(copy))
1014                         return PTR_ERR(copy);
1015         }
1016         mode = convert_mode(&msgtyp, msgflg);
1017
1018         rcu_read_lock();
1019         msq = msq_obtain_object_check(ns, msqid);
1020         if (IS_ERR(msq)) {
1021                 rcu_read_unlock();
1022                 free_copy(copy);
1023                 return PTR_ERR(msq);
1024         }
1025
1026         for (;;) {
1027                 struct msg_receiver msr_d;
1028
1029                 msg = ERR_PTR(-EACCES);
1030                 if (ipcperms(ns, &msq->q_perm, S_IRUGO))
1031                         goto out_unlock1;
1032
1033                 ipc_lock_object(&msq->q_perm);
1034
1035                 /* raced with RMID? */
1036                 if (!ipc_valid_object(&msq->q_perm)) {
1037                         msg = ERR_PTR(-EIDRM);
1038                         goto out_unlock0;
1039                 }
1040
1041                 msg = find_msg(msq, &msgtyp, mode);
1042                 if (!IS_ERR(msg)) {
1043                         /*
1044                          * Found a suitable message.
1045                          * Unlink it from the queue.
1046                          */
1047                         if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
1048                                 msg = ERR_PTR(-E2BIG);
1049                                 goto out_unlock0;
1050                         }
1051                         /*
1052                          * If we are copying, then do not unlink message and do
1053                          * not update queue parameters.
1054                          */
1055                         if (msgflg & MSG_COPY) {
1056                                 msg = copy_msg(msg, copy);
1057                                 goto out_unlock0;
1058                         }
1059
1060                         list_del(&msg->m_list);
1061                         msq->q_qnum--;
1062                         msq->q_rtime = get_seconds();
1063                         msq->q_lrpid = task_tgid_vnr(current);
1064                         msq->q_cbytes -= msg->m_ts;
1065                         atomic_sub(msg->m_ts, &ns->msg_bytes);
1066                         atomic_dec(&ns->msg_hdrs);
1067                         ss_wakeup(msq, &wake_q, false);
1068
1069                         goto out_unlock0;
1070                 }
1071
1072                 /* No message waiting. Wait for a message */
1073                 if (msgflg & IPC_NOWAIT) {
1074                         msg = ERR_PTR(-ENOMSG);
1075                         goto out_unlock0;
1076                 }
1077
1078                 list_add_tail(&msr_d.r_list, &msq->q_receivers);
1079                 msr_d.r_tsk = current;
1080                 msr_d.r_msgtype = msgtyp;
1081                 msr_d.r_mode = mode;
1082                 if (msgflg & MSG_NOERROR)
1083                         msr_d.r_maxsize = INT_MAX;
1084                 else
1085                         msr_d.r_maxsize = bufsz;
1086                 msr_d.r_msg = ERR_PTR(-EAGAIN);
1087                 __set_current_state(TASK_INTERRUPTIBLE);
1088
1089                 ipc_unlock_object(&msq->q_perm);
1090                 rcu_read_unlock();
1091                 schedule();
1092
1093                 /*
1094                  * Lockless receive, part 1:
1095                  * We don't hold a reference to the queue and getting a
1096                  * reference would defeat the idea of a lockless operation,
1097                  * thus the code relies on rcu to guarantee the existence of
1098                  * msq:
1099                  * Prior to destruction, expunge_all(-EIRDM) changes r_msg.
1100                  * Thus if r_msg is -EAGAIN, then the queue not yet destroyed.
1101                  */
1102                 rcu_read_lock();
1103
1104                 /*
1105                  * Lockless receive, part 2:
1106                  * The work in pipelined_send() and expunge_all():
1107                  * - Set pointer to message
1108                  * - Queue the receiver task for later wakeup
1109                  * - Wake up the process after the lock is dropped.
1110                  *
1111                  * Should the process wake up before this wakeup (due to a
1112                  * signal) it will either see the message and continue ...
1113                  */
1114                 msg = READ_ONCE(msr_d.r_msg);
1115                 if (msg != ERR_PTR(-EAGAIN))
1116                         goto out_unlock1;
1117
1118                  /*
1119                   * ... or see -EAGAIN, acquire the lock to check the message
1120                   * again.
1121                   */
1122                 ipc_lock_object(&msq->q_perm);
1123
1124                 msg = msr_d.r_msg;
1125                 if (msg != ERR_PTR(-EAGAIN))
1126                         goto out_unlock0;
1127
1128                 list_del(&msr_d.r_list);
1129                 if (signal_pending(current)) {
1130                         msg = ERR_PTR(-ERESTARTNOHAND);
1131                         goto out_unlock0;
1132                 }
1133
1134                 ipc_unlock_object(&msq->q_perm);
1135         }
1136
1137 out_unlock0:
1138         ipc_unlock_object(&msq->q_perm);
1139         wake_up_q(&wake_q);
1140 out_unlock1:
1141         rcu_read_unlock();
1142         if (IS_ERR(msg)) {
1143                 free_copy(copy);
1144                 return PTR_ERR(msg);
1145         }
1146
1147         bufsz = msg_handler(buf, msg, bufsz);
1148         free_msg(msg);
1149
1150         return bufsz;
1151 }
1152
1153 long ksys_msgrcv(int msqid, struct msgbuf __user *msgp, size_t msgsz,
1154                  long msgtyp, int msgflg)
1155 {
1156         return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill);
1157 }
1158
1159 SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
1160                 long, msgtyp, int, msgflg)
1161 {
1162         return ksys_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg);
1163 }
1164
1165 #ifdef CONFIG_COMPAT
1166 static long compat_do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
1167 {
1168         struct compat_msgbuf __user *msgp = dest;
1169         size_t msgsz;
1170
1171         if (put_user(msg->m_type, &msgp->mtype))
1172                 return -EFAULT;
1173
1174         msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
1175         if (store_msg(msgp->mtext, msg, msgsz))
1176                 return -EFAULT;
1177         return msgsz;
1178 }
1179
1180 long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz,
1181                         compat_long_t msgtyp, int msgflg)
1182 {
1183         return do_msgrcv(msqid, compat_ptr(msgp), (ssize_t)msgsz, (long)msgtyp,
1184                          msgflg, compat_do_msg_fill);
1185 }
1186
1187 COMPAT_SYSCALL_DEFINE5(msgrcv, int, msqid, compat_uptr_t, msgp,
1188                        compat_ssize_t, msgsz, compat_long_t, msgtyp,
1189                        int, msgflg)
1190 {
1191         return compat_ksys_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg);
1192 }
1193 #endif
1194
1195 int msg_init_ns(struct ipc_namespace *ns)
1196 {
1197         ns->msg_ctlmax = MSGMAX;
1198         ns->msg_ctlmnb = MSGMNB;
1199         ns->msg_ctlmni = MSGMNI;
1200
1201         atomic_set(&ns->msg_bytes, 0);
1202         atomic_set(&ns->msg_hdrs, 0);
1203         return ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
1204 }
1205
1206 #ifdef CONFIG_IPC_NS
1207 void msg_exit_ns(struct ipc_namespace *ns)
1208 {
1209         free_ipcs(ns, &msg_ids(ns), freeque);
1210         idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr);
1211         rhashtable_destroy(&ns->ids[IPC_MSG_IDS].key_ht);
1212 }
1213 #endif
1214
1215 #ifdef CONFIG_PROC_FS
1216 static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
1217 {
1218         struct user_namespace *user_ns = seq_user_ns(s);
1219         struct kern_ipc_perm *ipcp = it;
1220         struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
1221
1222         seq_printf(s,
1223                    "%10d %10d  %4o  %10lu %10lu %5u %5u %5u %5u %5u %5u %10llu %10llu %10llu\n",
1224                    msq->q_perm.key,
1225                    msq->q_perm.id,
1226                    msq->q_perm.mode,
1227                    msq->q_cbytes,
1228                    msq->q_qnum,
1229                    msq->q_lspid,
1230                    msq->q_lrpid,
1231                    from_kuid_munged(user_ns, msq->q_perm.uid),
1232                    from_kgid_munged(user_ns, msq->q_perm.gid),
1233                    from_kuid_munged(user_ns, msq->q_perm.cuid),
1234                    from_kgid_munged(user_ns, msq->q_perm.cgid),
1235                    msq->q_stime,
1236                    msq->q_rtime,
1237                    msq->q_ctime);
1238
1239         return 0;
1240 }
1241 #endif
1242
1243 int __init msg_init(void)
1244 {
1245         const int err = msg_init_ns(&init_ipc_ns);
1246
1247         ipc_init_proc_interface("sysvipc/msg",
1248                                 "       key      msqid perms      cbytes       qnum lspid lrpid   uid   gid  cuid  cgid      stime      rtime      ctime\n",
1249                                 IPC_MSG_IDS, sysvipc_msg_proc_show);
1250         return err;
1251 }