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         struct msg_queue *msq;
 480         int id = 0;
 481         int err;
 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                 id = 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         }
 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         ipc_lock_object(&msq->q_perm);
 510
 511         if (!ipc_valid_object(&msq->q_perm)) {
 512                 ipc_unlock_object(&msq->q_perm);
 513                 err = -EIDRM;
 514                 goto out_unlock;
 515         }
 516
 517         kernel_to_ipc64_perm(&msq->q_perm, &p->msg_perm);
 518         p->msg_stime  = msq->q_stime;
 519         p->msg_rtime  = msq->q_rtime;
 520         p->msg_ctime  = msq->q_ctime;
 521         p->msg_cbytes = msq->q_cbytes;
 522         p->msg_qnum   = msq->q_qnum;
 523         p->msg_qbytes = msq->q_qbytes;
 524         p->msg_lspid  = msq->q_lspid;
 525         p->msg_lrpid  = msq->q_lrpid;
 526
 527         ipc_unlock_object(&msq->q_perm);
 528         rcu_read_unlock();
 529         return id;
 530
 531 out_unlock:
 532         rcu_read_unlock();
 533         return err;
 534 }
 535
 536 SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
 537 {
 538         int version;
 539         struct ipc_namespace *ns;
 540         struct msqid64_ds msqid64;
 541         int err;
 542
 543         if (msqid < 0 || cmd < 0)
 544                 return -EINVAL;
 545
 546         version = ipc_parse_version(&cmd);
 547         ns = current->nsproxy->ipc_ns;
 548
 549         switch (cmd) {
 550         case IPC_INFO:
 551         case MSG_INFO: {
 552                 struct msginfo msginfo;
 553                 err = msgctl_info(ns, msqid, cmd, &msginfo);
 554                 if (err < 0)
 555                         return err;
 556                 if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
 557                         err = -EFAULT;
 558                 return err;
 559         }
 560         case MSG_STAT:  /* msqid is an index rather than a msg queue id */
 561         case IPC_STAT:
 562                 err = msgctl_stat(ns, msqid, cmd, &msqid64);
 563                 if (err < 0)
 564                         return err;
 565                 if (copy_msqid_to_user(buf, &msqid64, version))
 566                         err = -EFAULT;
 567                 return err;
 568         case IPC_SET:
 569                 if (copy_msqid_from_user(&msqid64, buf, version))
 570                         return -EFAULT;
 571                 /* fallthru */
 572         case IPC_RMID:
 573                 return msgctl_down(ns, msqid, cmd, &msqid64);
 574         default:
 575                 return  -EINVAL;
 576         }
 577 }
 578
 579 #ifdef CONFIG_COMPAT
 580
 581 struct compat_msqid_ds {
 582         struct compat_ipc_perm msg_perm;
 583         compat_uptr_t msg_first;
 584         compat_uptr_t msg_last;
 585         compat_time_t msg_stime;
 586         compat_time_t msg_rtime;
 587         compat_time_t msg_ctime;
 588         compat_ulong_t msg_lcbytes;
 589         compat_ulong_t msg_lqbytes;
 590         unsigned short msg_cbytes;
 591         unsigned short msg_qnum;
 592         unsigned short msg_qbytes;
 593         compat_ipc_pid_t msg_lspid;
 594         compat_ipc_pid_t msg_lrpid;
 595 };
 596
 597 static int copy_compat_msqid_from_user(struct msqid64_ds *out, void __user *buf,
 598                                         int version)
 599 {
 600         memset(out, 0, sizeof(*out));
 601         if (version == IPC_64) {
 602                 struct compat_msqid64_ds __user *p = buf;
 603                 if (get_compat_ipc64_perm(&out->msg_perm, &p->msg_perm))
 604                         return -EFAULT;
 605                 if (get_user(out->msg_qbytes, &p->msg_qbytes))
 606                         return -EFAULT;
 607         } else {
 608                 struct compat_msqid_ds __user *p = buf;
 609                 if (get_compat_ipc_perm(&out->msg_perm, &p->msg_perm))
 610                         return -EFAULT;
 611                 if (get_user(out->msg_qbytes, &p->msg_qbytes))
 612                         return -EFAULT;
 613         }
 614         return 0;
 615 }
 616
 617 static int copy_compat_msqid_to_user(void __user *buf, struct msqid64_ds *in,
 618                                         int version)
 619 {
 620         if (version == IPC_64) {
 621                 struct compat_msqid64_ds v;
 622                 memset(&v, 0, sizeof(v));
 623                 to_compat_ipc64_perm(&v.msg_perm, &in->msg_perm);
 624                 v.msg_stime = in->msg_stime;
 625                 v.msg_rtime = in->msg_rtime;
 626                 v.msg_ctime = in->msg_ctime;
 627                 v.msg_cbytes = in->msg_cbytes;
 628                 v.msg_qnum = in->msg_qnum;
 629                 v.msg_qbytes = in->msg_qbytes;
 630                 v.msg_lspid = in->msg_lspid;
 631                 v.msg_lrpid = in->msg_lrpid;
 632                 return copy_to_user(buf, &v, sizeof(v));
 633         } else {
 634                 struct compat_msqid_ds v;
 635                 memset(&v, 0, sizeof(v));
 636                 to_compat_ipc_perm(&v.msg_perm, &in->msg_perm);
 637                 v.msg_stime = in->msg_stime;
 638                 v.msg_rtime = in->msg_rtime;
 639                 v.msg_ctime = in->msg_ctime;
 640                 v.msg_cbytes = in->msg_cbytes;
 641                 v.msg_qnum = in->msg_qnum;
 642                 v.msg_qbytes = in->msg_qbytes;
 643                 v.msg_lspid = in->msg_lspid;
 644                 v.msg_lrpid = in->msg_lrpid;
 645                 return copy_to_user(buf, &v, sizeof(v));
 646         }
 647 }
 648
 649 COMPAT_SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, void __user *, uptr)
 650 {
 651         struct ipc_namespace *ns;
 652         int err;
 653         struct msqid64_ds msqid64;
 654         int version = compat_ipc_parse_version(&cmd);
 655
 656         ns = current->nsproxy->ipc_ns;
 657
 658         if (msqid < 0 || cmd < 0)
 659                 return -EINVAL;
 660
 661         switch (cmd & (~IPC_64)) {
 662         case IPC_INFO:
 663         case MSG_INFO: {
 664                 struct msginfo msginfo;
 665                 err = msgctl_info(ns, msqid, cmd, &msginfo);
 666                 if (err < 0)
 667                         return err;
 668                 if (copy_to_user(uptr, &msginfo, sizeof(struct msginfo)))
 669                         err = -EFAULT;
 670                 return err;
 671         }
 672         case IPC_STAT:
 673         case MSG_STAT:
 674                 err = msgctl_stat(ns, msqid, cmd, &msqid64);
 675                 if (err < 0)
 676                         return err;
 677                 if (copy_compat_msqid_to_user(uptr, &msqid64, version))
 678                         err = -EFAULT;
 679                 return err;
 680         case IPC_SET:
 681                 if (copy_compat_msqid_from_user(&msqid64, uptr, version))
 682                         return -EFAULT;
 683                 /* fallthru */
 684         case IPC_RMID:
 685                 return msgctl_down(ns, msqid, cmd, &msqid64);
 686         default:
 687                 return -EINVAL;
 688         }
 689 }
 690 #endif
 691
 692 static int testmsg(struct msg_msg *msg, long type, int mode)
 693 {
 694         switch (mode) {
 695         case SEARCH_ANY:
 696         case SEARCH_NUMBER:
 697                 return 1;
 698         case SEARCH_LESSEQUAL:
 699                 if (msg->m_type <= type)
 700                         return 1;
 701                 break;
 702         case SEARCH_EQUAL:
 703                 if (msg->m_type == type)
 704                         return 1;
 705                 break;
 706         case SEARCH_NOTEQUAL:
 707                 if (msg->m_type != type)
 708                         return 1;
 709                 break;
 710         }
 711         return 0;
 712 }
 713
 714 static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg,
 715                                  struct wake_q_head *wake_q)
 716 {
 717         struct msg_receiver *msr, *t;
 718
 719         list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
 720                 if (testmsg(msg, msr->r_msgtype, msr->r_mode) &&
 721                     !security_msg_queue_msgrcv(msq, msg, msr->r_tsk,
 722                                                msr->r_msgtype, msr->r_mode)) {
 723
 724                         list_del(&msr->r_list);
 725                         if (msr->r_maxsize < msg->m_ts) {
 726                                 wake_q_add(wake_q, msr->r_tsk);
 727                                 WRITE_ONCE(msr->r_msg, ERR_PTR(-E2BIG));
 728                         } else {
 729                                 msq->q_lrpid = task_pid_vnr(msr->r_tsk);
 730                                 msq->q_rtime = get_seconds();
 731
 732                                 wake_q_add(wake_q, msr->r_tsk);
 733                                 WRITE_ONCE(msr->r_msg, msg);
 734                                 return 1;
 735                         }
 736                 }
 737         }
 738
 739         return 0;
 740 }
 741
 742 static long do_msgsnd(int msqid, long mtype, void __user *mtext,
 743                 size_t msgsz, int msgflg)
 744 {
 745         struct msg_queue *msq;
 746         struct msg_msg *msg;
 747         int err;
 748         struct ipc_namespace *ns;
 749         DEFINE_WAKE_Q(wake_q);
 750
 751         ns = current->nsproxy->ipc_ns;
 752
 753         if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0)
 754                 return -EINVAL;
 755         if (mtype < 1)
 756                 return -EINVAL;
 757
 758         msg = load_msg(mtext, msgsz);
 759         if (IS_ERR(msg))
 760                 return PTR_ERR(msg);
 761
 762         msg->m_type = mtype;
 763         msg->m_ts = msgsz;
 764
 765         rcu_read_lock();
 766         msq = msq_obtain_object_check(ns, msqid);
 767         if (IS_ERR(msq)) {
 768                 err = PTR_ERR(msq);
 769                 goto out_unlock1;
 770         }
 771
 772         ipc_lock_object(&msq->q_perm);
 773
 774         for (;;) {
 775                 struct msg_sender s;
 776
 777                 err = -EACCES;
 778                 if (ipcperms(ns, &msq->q_perm, S_IWUGO))
 779                         goto out_unlock0;
 780
 781                 /* raced with RMID? */
 782                 if (!ipc_valid_object(&msq->q_perm)) {
 783                         err = -EIDRM;
 784                         goto out_unlock0;
 785                 }
 786
 787                 err = security_msg_queue_msgsnd(msq, msg, msgflg);
 788                 if (err)
 789                         goto out_unlock0;
 790
 791                 if (msg_fits_inqueue(msq, msgsz))
 792                         break;
 793
 794                 /* queue full, wait: */
 795                 if (msgflg & IPC_NOWAIT) {
 796                         err = -EAGAIN;
 797                         goto out_unlock0;
 798                 }
 799
 800                 /* enqueue the sender and prepare to block */
 801                 ss_add(msq, &s, msgsz);
 802
 803                 if (!ipc_rcu_getref(&msq->q_perm)) {
 804                         err = -EIDRM;
 805                         goto out_unlock0;
 806                 }
 807
 808                 ipc_unlock_object(&msq->q_perm);
 809                 rcu_read_unlock();
 810                 schedule();
 811
 812                 rcu_read_lock();
 813                 ipc_lock_object(&msq->q_perm);
 814
 815                 ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
 816                 /* raced with RMID? */
 817                 if (!ipc_valid_object(&msq->q_perm)) {
 818                         err = -EIDRM;
 819                         goto out_unlock0;
 820                 }
 821                 ss_del(&s);
 822
 823                 if (signal_pending(current)) {
 824                         err = -ERESTARTNOHAND;
 825                         goto out_unlock0;
 826                 }
 827
 828         }
 829
 830         msq->q_lspid = task_tgid_vnr(current);
 831         msq->q_stime = get_seconds();
 832
 833         if (!pipelined_send(msq, msg, &wake_q)) {
 834                 /* no one is waiting for this message, enqueue it */
 835                 list_add_tail(&msg->m_list, &msq->q_messages);
 836                 msq->q_cbytes += msgsz;
 837                 msq->q_qnum++;
 838                 atomic_add(msgsz, &ns->msg_bytes);
 839                 atomic_inc(&ns->msg_hdrs);
 840         }
 841
 842         err = 0;
 843         msg = NULL;
 844
 845 out_unlock0:
 846         ipc_unlock_object(&msq->q_perm);
 847         wake_up_q(&wake_q);
 848 out_unlock1:
 849         rcu_read_unlock();
 850         if (msg != NULL)
 851                 free_msg(msg);
 852         return err;
 853 }
 854
 855 SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
 856                 int, msgflg)
 857 {
 858         long mtype;
 859
 860         if (get_user(mtype, &msgp->mtype))
 861                 return -EFAULT;
 862         return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg);
 863 }
 864
 865 #ifdef CONFIG_COMPAT
 866
 867 struct compat_msgbuf {
 868         compat_long_t mtype;
 869         char mtext[1];
 870 };
 871
 872 COMPAT_SYSCALL_DEFINE4(msgsnd, int, msqid, compat_uptr_t, msgp,
 873                        compat_ssize_t, msgsz, int, msgflg)
 874 {
 875         struct compat_msgbuf __user *up = compat_ptr(msgp);
 876         compat_long_t mtype;
 877
 878         if (get_user(mtype, &up->mtype))
 879                 return -EFAULT;
 880         return do_msgsnd(msqid, mtype, up->mtext, (ssize_t)msgsz, msgflg);
 881 }
 882 #endif
 883
 884 static inline int convert_mode(long *msgtyp, int msgflg)
 885 {
 886         if (msgflg & MSG_COPY)
 887                 return SEARCH_NUMBER;
 888         /*
 889          *  find message of correct type.
 890          *  msgtyp = 0 => get first.
 891          *  msgtyp > 0 => get first message of matching type.
 892          *  msgtyp < 0 => get message with least type must be < abs(msgtype).
 893          */
 894         if (*msgtyp == 0)
 895                 return SEARCH_ANY;
 896         if (*msgtyp < 0) {
 897                 if (*msgtyp == LONG_MIN) /* -LONG_MIN is undefined */
 898                         *msgtyp = LONG_MAX;
 899                 else
 900                         *msgtyp = -*msgtyp;
 901                 return SEARCH_LESSEQUAL;
 902         }
 903         if (msgflg & MSG_EXCEPT)
 904                 return SEARCH_NOTEQUAL;
 905         return SEARCH_EQUAL;
 906 }
 907
 908 static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
 909 {
 910         struct msgbuf __user *msgp = dest;
 911         size_t msgsz;
 912
 913         if (put_user(msg->m_type, &msgp->mtype))
 914                 return -EFAULT;
 915
 916         msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
 917         if (store_msg(msgp->mtext, msg, msgsz))
 918                 return -EFAULT;
 919         return msgsz;
 920 }
 921
 922 #ifdef CONFIG_CHECKPOINT_RESTORE
 923 /*
 924  * This function creates new kernel message structure, large enough to store
 925  * bufsz message bytes.
 926  */
 927 static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
 928 {
 929         struct msg_msg *copy;
 930
 931         /*
 932          * Create dummy message to copy real message to.
 933          */
 934         copy = load_msg(buf, bufsz);
 935         if (!IS_ERR(copy))
 936                 copy->m_ts = bufsz;
 937         return copy;
 938 }
 939
 940 static inline void free_copy(struct msg_msg *copy)
 941 {
 942         if (copy)
 943                 free_msg(copy);
 944 }
 945 #else
 946 static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
 947 {
 948         return ERR_PTR(-ENOSYS);
 949 }
 950
 951 static inline void free_copy(struct msg_msg *copy)
 952 {
 953 }
 954 #endif
 955
 956 static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode)
 957 {
 958         struct msg_msg *msg, *found = NULL;
 959         long count = 0;
 960
 961         list_for_each_entry(msg, &msq->q_messages, m_list) {
 962                 if (testmsg(msg, *msgtyp, mode) &&
 963                     !security_msg_queue_msgrcv(msq, msg, current,
 964                                                *msgtyp, mode)) {
 965                         if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) {
 966                                 *msgtyp = msg->m_type - 1;
 967                                 found = msg;
 968                         } else if (mode == SEARCH_NUMBER) {
 969                                 if (*msgtyp == count)
 970                                         return msg;
 971                         } else
 972                                 return msg;
 973                         count++;
 974                 }
 975         }
 976
 977         return found ?: ERR_PTR(-EAGAIN);
 978 }
 979
 980 static long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg,
 981                long (*msg_handler)(void __user *, struct msg_msg *, size_t))
 982 {
 983         int mode;
 984         struct msg_queue *msq;
 985         struct ipc_namespace *ns;
 986         struct msg_msg *msg, *copy = NULL;
 987         DEFINE_WAKE_Q(wake_q);
 988
 989         ns = current->nsproxy->ipc_ns;
 990
 991         if (msqid < 0 || (long) bufsz < 0)
 992                 return -EINVAL;
 993
 994         if (msgflg & MSG_COPY) {
 995                 if ((msgflg & MSG_EXCEPT) || !(msgflg & IPC_NOWAIT))
 996                         return -EINVAL;
 997                 copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax));
 998                 if (IS_ERR(copy))
 999                         return PTR_ERR(copy);
1000         }
1001         mode = convert_mode(&msgtyp, msgflg);
1002
1003         rcu_read_lock();
1004         msq = msq_obtain_object_check(ns, msqid);
1005         if (IS_ERR(msq)) {
1006                 rcu_read_unlock();
1007                 free_copy(copy);
1008                 return PTR_ERR(msq);
1009         }
1010
1011         for (;;) {
1012                 struct msg_receiver msr_d;
1013
1014                 msg = ERR_PTR(-EACCES);
1015                 if (ipcperms(ns, &msq->q_perm, S_IRUGO))
1016                         goto out_unlock1;
1017
1018                 ipc_lock_object(&msq->q_perm);
1019
1020                 /* raced with RMID? */
1021                 if (!ipc_valid_object(&msq->q_perm)) {
1022                         msg = ERR_PTR(-EIDRM);
1023                         goto out_unlock0;
1024                 }
1025
1026                 msg = find_msg(msq, &msgtyp, mode);
1027                 if (!IS_ERR(msg)) {
1028                         /*
1029                          * Found a suitable message.
1030                          * Unlink it from the queue.
1031                          */
1032                         if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
1033                                 msg = ERR_PTR(-E2BIG);
1034                                 goto out_unlock0;
1035                         }
1036                         /*
1037                          * If we are copying, then do not unlink message and do
1038                          * not update queue parameters.
1039                          */
1040                         if (msgflg & MSG_COPY) {
1041                                 msg = copy_msg(msg, copy);
1042                                 goto out_unlock0;
1043                         }
1044
1045                         list_del(&msg->m_list);
1046                         msq->q_qnum--;
1047                         msq->q_rtime = get_seconds();
1048                         msq->q_lrpid = task_tgid_vnr(current);
1049                         msq->q_cbytes -= msg->m_ts;
1050                         atomic_sub(msg->m_ts, &ns->msg_bytes);
1051                         atomic_dec(&ns->msg_hdrs);
1052                         ss_wakeup(msq, &wake_q, false);
1053
1054                         goto out_unlock0;
1055                 }
1056
1057                 /* No message waiting. Wait for a message */
1058                 if (msgflg & IPC_NOWAIT) {
1059                         msg = ERR_PTR(-ENOMSG);
1060                         goto out_unlock0;
1061                 }
1062
1063                 list_add_tail(&msr_d.r_list, &msq->q_receivers);
1064                 msr_d.r_tsk = current;
1065                 msr_d.r_msgtype = msgtyp;
1066                 msr_d.r_mode = mode;
1067                 if (msgflg & MSG_NOERROR)
1068                         msr_d.r_maxsize = INT_MAX;
1069                 else
1070                         msr_d.r_maxsize = bufsz;
1071                 msr_d.r_msg = ERR_PTR(-EAGAIN);
1072                 __set_current_state(TASK_INTERRUPTIBLE);
1073
1074                 ipc_unlock_object(&msq->q_perm);
1075                 rcu_read_unlock();
1076                 schedule();
1077
1078                 /*
1079                  * Lockless receive, part 1:
1080                  * We don't hold a reference to the queue and getting a
1081                  * reference would defeat the idea of a lockless operation,
1082                  * thus the code relies on rcu to guarantee the existence of
1083                  * msq:
1084                  * Prior to destruction, expunge_all(-EIRDM) changes r_msg.
1085                  * Thus if r_msg is -EAGAIN, then the queue not yet destroyed.
1086                  */
1087                 rcu_read_lock();
1088
1089                 /*
1090                  * Lockless receive, part 2:
1091                  * The work in pipelined_send() and expunge_all():
1092                  * - Set pointer to message
1093                  * - Queue the receiver task for later wakeup
1094                  * - Wake up the process after the lock is dropped.
1095                  *
1096                  * Should the process wake up before this wakeup (due to a
1097                  * signal) it will either see the message and continue ...
1098                  */
1099                 msg = READ_ONCE(msr_d.r_msg);
1100                 if (msg != ERR_PTR(-EAGAIN))
1101                         goto out_unlock1;
1102
1103                  /*
1104                   * ... or see -EAGAIN, acquire the lock to check the message
1105                   * again.
1106                   */
1107                 ipc_lock_object(&msq->q_perm);
1108
1109                 msg = msr_d.r_msg;
1110                 if (msg != ERR_PTR(-EAGAIN))
1111                         goto out_unlock0;
1112
1113                 list_del(&msr_d.r_list);
1114                 if (signal_pending(current)) {
1115                         msg = ERR_PTR(-ERESTARTNOHAND);
1116                         goto out_unlock0;
1117                 }
1118
1119                 ipc_unlock_object(&msq->q_perm);
1120         }
1121
1122 out_unlock0:
1123         ipc_unlock_object(&msq->q_perm);
1124         wake_up_q(&wake_q);
1125 out_unlock1:
1126         rcu_read_unlock();
1127         if (IS_ERR(msg)) {
1128                 free_copy(copy);
1129                 return PTR_ERR(msg);
1130         }
1131
1132         bufsz = msg_handler(buf, msg, bufsz);
1133         free_msg(msg);
1134
1135         return bufsz;
1136 }
1137
1138 SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
1139                 long, msgtyp, int, msgflg)
1140 {
1141         return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill);
1142 }
1143
1144 #ifdef CONFIG_COMPAT
1145 static long compat_do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
1146 {
1147         struct compat_msgbuf __user *msgp = dest;
1148         size_t msgsz;
1149
1150         if (put_user(msg->m_type, &msgp->mtype))
1151                 return -EFAULT;
1152
1153         msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
1154         if (store_msg(msgp->mtext, msg, msgsz))
1155                 return -EFAULT;
1156         return msgsz;
1157 }
1158
1159 COMPAT_SYSCALL_DEFINE5(msgrcv, int, msqid, compat_uptr_t, msgp,
1160                        compat_ssize_t, msgsz, compat_long_t, msgtyp, int, msgflg)
1161 {
1162         return do_msgrcv(msqid, compat_ptr(msgp), (ssize_t)msgsz, (long)msgtyp,
1163                          msgflg, compat_do_msg_fill);
1164 }
1165 #endif
1166
1167 int msg_init_ns(struct ipc_namespace *ns)
1168 {
1169         ns->msg_ctlmax = MSGMAX;
1170         ns->msg_ctlmnb = MSGMNB;
1171         ns->msg_ctlmni = MSGMNI;
1172
1173         atomic_set(&ns->msg_bytes, 0);
1174         atomic_set(&ns->msg_hdrs, 0);
1175         return ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
1176 }
1177
1178 #ifdef CONFIG_IPC_NS
1179 void msg_exit_ns(struct ipc_namespace *ns)
1180 {
1181         free_ipcs(ns, &msg_ids(ns), freeque);
1182         idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr);
1183         rhashtable_destroy(&ns->ids[IPC_MSG_IDS].key_ht);
1184 }
1185 #endif
1186
1187 #ifdef CONFIG_PROC_FS
1188 static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
1189 {
1190         struct user_namespace *user_ns = seq_user_ns(s);
1191         struct kern_ipc_perm *ipcp = it;
1192         struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
1193
1194         seq_printf(s,
1195                    "%10d %10d  %4o  %10lu %10lu %5u %5u %5u %5u %5u %5u %10llu %10llu %10llu\n",
1196                    msq->q_perm.key,
1197                    msq->q_perm.id,
1198                    msq->q_perm.mode,
1199                    msq->q_cbytes,
1200                    msq->q_qnum,
1201                    msq->q_lspid,
1202                    msq->q_lrpid,
1203                    from_kuid_munged(user_ns, msq->q_perm.uid),
1204                    from_kgid_munged(user_ns, msq->q_perm.gid),
1205                    from_kuid_munged(user_ns, msq->q_perm.cuid),
1206                    from_kgid_munged(user_ns, msq->q_perm.cgid),
1207                    msq->q_stime,
1208                    msq->q_rtime,
1209                    msq->q_ctime);
1210
1211         return 0;
1212 }
1213 #endif
1214
1215 int __init msg_init(void)
1216 {
1217         const int err = msg_init_ns(&init_ipc_ns);
1218
1219         ipc_init_proc_interface("sysvipc/msg",
1220                                 "       key      msqid perms      cbytes       qnum lspid lrpid   uid   gid  cuid  cgid      stime      rtime      ctime\n",
1221                                 IPC_MSG_IDS, sysvipc_msg_proc_show);
1222         return err;
1223 }