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 #include <linux/rhashtable.h> 42 43 #include <asm/current.h> 44 #include <linux/uaccess.h> 45 #include "util.h" 46 47 /* one msq_queue structure for each present queue on the system */ 48 struct msg_queue { 49 struct kern_ipc_perm q_perm; 50 time64_t q_stime; /* last msgsnd time */ 51 time64_t q_rtime; /* last msgrcv time */ 52 time64_t q_ctime; /* last change time */ 53 unsigned long q_cbytes; /* current number of bytes on queue */ 54 unsigned long q_qnum; /* number of messages in queue */ 55 unsigned long q_qbytes; /* max number of bytes on queue */ 56 struct pid *q_lspid; /* pid of last msgsnd */ 57 struct pid *q_lrpid; /* last receive pid */ 58 59 struct list_head q_messages; 60 struct list_head q_receivers; 61 struct list_head q_senders; 62 } __randomize_layout; 63 64 /* 65 * MSG_BARRIER Locking: 66 * 67 * Similar to the optimization used in ipc/mqueue.c, one syscall return path 68 * does not acquire any locks when it sees that a message exists in 69 * msg_receiver.r_msg. Therefore r_msg is set using smp_store_release() 70 * and accessed using READ_ONCE()+smp_acquire__after_ctrl_dep(). In addition, 71 * wake_q_add_safe() is used. See ipc/mqueue.c for more details 72 */ 73 74 /* one msg_receiver structure for each sleeping receiver */ 75 struct msg_receiver { 76 struct list_head r_list; 77 struct task_struct *r_tsk; 78 79 int r_mode; 80 long r_msgtype; 81 long r_maxsize; 82 83 struct msg_msg *r_msg; 84 }; 85 86 /* one msg_sender for each sleeping sender */ 87 struct msg_sender { 88 struct list_head list; 89 struct task_struct *tsk; 90 size_t msgsz; 91 }; 92 93 #define SEARCH_ANY 1 94 #define SEARCH_EQUAL 2 95 #define SEARCH_NOTEQUAL 3 96 #define SEARCH_LESSEQUAL 4 97 #define SEARCH_NUMBER 5 98 99 #define msg_ids(ns) ((ns)->ids[IPC_MSG_IDS]) 100 101 static inline struct msg_queue *msq_obtain_object(struct ipc_namespace *ns, int id) 102 { 103 struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&msg_ids(ns), id); 104 105 if (IS_ERR(ipcp)) 106 return ERR_CAST(ipcp); 107 108 return container_of(ipcp, struct msg_queue, q_perm); 109 } 110 111 static inline struct msg_queue *msq_obtain_object_check(struct ipc_namespace *ns, 112 int id) 113 { 114 struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&msg_ids(ns), id); 115 116 if (IS_ERR(ipcp)) 117 return ERR_CAST(ipcp); 118 119 return container_of(ipcp, struct msg_queue, q_perm); 120 } 121 122 static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s) 123 { 124 ipc_rmid(&msg_ids(ns), &s->q_perm); 125 } 126 127 static void msg_rcu_free(struct rcu_head *head) 128 { 129 struct kern_ipc_perm *p = container_of(head, struct kern_ipc_perm, rcu); 130 struct msg_queue *msq = container_of(p, struct msg_queue, q_perm); 131 132 security_msg_queue_free(&msq->q_perm); 133 kvfree(msq); 134 } 135 136 /** 137 * newque - Create a new msg queue 138 * @ns: namespace 139 * @params: ptr to the structure that contains the key and msgflg 140 * 141 * Called with msg_ids.rwsem held (writer) 142 */ 143 static int newque(struct ipc_namespace *ns, struct ipc_params *params) 144 { 145 struct msg_queue *msq; 146 int retval; 147 key_t key = params->key; 148 int msgflg = params->flg; 149 150 msq = kvmalloc(sizeof(*msq), GFP_KERNEL); 151 if (unlikely(!msq)) 152 return -ENOMEM; 153 154 msq->q_perm.mode = msgflg & S_IRWXUGO; 155 msq->q_perm.key = key; 156 157 msq->q_perm.security = NULL; 158 retval = security_msg_queue_alloc(&msq->q_perm); 159 if (retval) { 160 kvfree(msq); 161 return retval; 162 } 163 164 msq->q_stime = msq->q_rtime = 0; 165 msq->q_ctime = ktime_get_real_seconds(); 166 msq->q_cbytes = msq->q_qnum = 0; 167 msq->q_qbytes = ns->msg_ctlmnb; 168 msq->q_lspid = msq->q_lrpid = NULL; 169 INIT_LIST_HEAD(&msq->q_messages); 170 INIT_LIST_HEAD(&msq->q_receivers); 171 INIT_LIST_HEAD(&msq->q_senders); 172 173 /* ipc_addid() locks msq upon success. */ 174 retval = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni); 175 if (retval < 0) { 176 ipc_rcu_putref(&msq->q_perm, msg_rcu_free); 177 return retval; 178 } 179 180 ipc_unlock_object(&msq->q_perm); 181 rcu_read_unlock(); 182 183 return msq->q_perm.id; 184 } 185 186 static inline bool msg_fits_inqueue(struct msg_queue *msq, size_t msgsz) 187 { 188 return msgsz + msq->q_cbytes <= msq->q_qbytes && 189 1 + msq->q_qnum <= msq->q_qbytes; 190 } 191 192 static inline void ss_add(struct msg_queue *msq, 193 struct msg_sender *mss, size_t msgsz) 194 { 195 mss->tsk = current; 196 mss->msgsz = msgsz; 197 /* 198 * No memory barrier required: we did ipc_lock_object(), 199 * and the waker obtains that lock before calling wake_q_add(). 200 */ 201 __set_current_state(TASK_INTERRUPTIBLE); 202 list_add_tail(&mss->list, &msq->q_senders); 203 } 204 205 static inline void ss_del(struct msg_sender *mss) 206 { 207 if (mss->list.next) 208 list_del(&mss->list); 209 } 210 211 static void ss_wakeup(struct msg_queue *msq, 212 struct wake_q_head *wake_q, bool kill) 213 { 214 struct msg_sender *mss, *t; 215 struct task_struct *stop_tsk = NULL; 216 struct list_head *h = &msq->q_senders; 217 218 list_for_each_entry_safe(mss, t, h, list) { 219 if (kill) 220 mss->list.next = NULL; 221 222 /* 223 * Stop at the first task we don't wakeup, 224 * we've already iterated the original 225 * sender queue. 226 */ 227 else if (stop_tsk == mss->tsk) 228 break; 229 /* 230 * We are not in an EIDRM scenario here, therefore 231 * verify that we really need to wakeup the task. 232 * To maintain current semantics and wakeup order, 233 * move the sender to the tail on behalf of the 234 * blocked task. 235 */ 236 else if (!msg_fits_inqueue(msq, mss->msgsz)) { 237 if (!stop_tsk) 238 stop_tsk = mss->tsk; 239 240 list_move_tail(&mss->list, &msq->q_senders); 241 continue; 242 } 243 244 wake_q_add(wake_q, mss->tsk); 245 } 246 } 247 248 static void expunge_all(struct msg_queue *msq, int res, 249 struct wake_q_head *wake_q) 250 { 251 struct msg_receiver *msr, *t; 252 253 list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) { 254 get_task_struct(msr->r_tsk); 255 256 /* see MSG_BARRIER for purpose/pairing */ 257 smp_store_release(&msr->r_msg, ERR_PTR(res)); 258 wake_q_add_safe(wake_q, msr->r_tsk); 259 } 260 } 261 262 /* 263 * freeque() wakes up waiters on the sender and receiver waiting queue, 264 * removes the message queue from message queue ID IDR, and cleans up all the 265 * messages associated with this queue. 266 * 267 * msg_ids.rwsem (writer) and the spinlock for this message queue are held 268 * before freeque() is called. msg_ids.rwsem remains locked on exit. 269 */ 270 static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp) 271 { 272 struct msg_msg *msg, *t; 273 struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm); 274 DEFINE_WAKE_Q(wake_q); 275 276 expunge_all(msq, -EIDRM, &wake_q); 277 ss_wakeup(msq, &wake_q, true); 278 msg_rmid(ns, msq); 279 ipc_unlock_object(&msq->q_perm); 280 wake_up_q(&wake_q); 281 rcu_read_unlock(); 282 283 list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) { 284 atomic_dec(&ns->msg_hdrs); 285 free_msg(msg); 286 } 287 atomic_sub(msq->q_cbytes, &ns->msg_bytes); 288 ipc_update_pid(&msq->q_lspid, NULL); 289 ipc_update_pid(&msq->q_lrpid, NULL); 290 ipc_rcu_putref(&msq->q_perm, msg_rcu_free); 291 } 292 293 long ksys_msgget(key_t key, int msgflg) 294 { 295 struct ipc_namespace *ns; 296 static const struct ipc_ops msg_ops = { 297 .getnew = newque, 298 .associate = security_msg_queue_associate, 299 }; 300 struct ipc_params msg_params; 301 302 ns = current->nsproxy->ipc_ns; 303 304 msg_params.key = key; 305 msg_params.flg = msgflg; 306 307 return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params); 308 } 309 310 SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg) 311 { 312 return ksys_msgget(key, msgflg); 313 } 314 315 static inline unsigned long 316 copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version) 317 { 318 switch (version) { 319 case IPC_64: 320 return copy_to_user(buf, in, sizeof(*in)); 321 case IPC_OLD: 322 { 323 struct msqid_ds out; 324 325 memset(&out, 0, sizeof(out)); 326 327 ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm); 328 329 out.msg_stime = in->msg_stime; 330 out.msg_rtime = in->msg_rtime; 331 out.msg_ctime = in->msg_ctime; 332 333 if (in->msg_cbytes > USHRT_MAX) 334 out.msg_cbytes = USHRT_MAX; 335 else 336 out.msg_cbytes = in->msg_cbytes; 337 out.msg_lcbytes = in->msg_cbytes; 338 339 if (in->msg_qnum > USHRT_MAX) 340 out.msg_qnum = USHRT_MAX; 341 else 342 out.msg_qnum = in->msg_qnum; 343 344 if (in->msg_qbytes > USHRT_MAX) 345 out.msg_qbytes = USHRT_MAX; 346 else 347 out.msg_qbytes = in->msg_qbytes; 348 out.msg_lqbytes = in->msg_qbytes; 349 350 out.msg_lspid = in->msg_lspid; 351 out.msg_lrpid = in->msg_lrpid; 352 353 return copy_to_user(buf, &out, sizeof(out)); 354 } 355 default: 356 return -EINVAL; 357 } 358 } 359 360 static inline unsigned long 361 copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version) 362 { 363 switch (version) { 364 case IPC_64: 365 if (copy_from_user(out, buf, sizeof(*out))) 366 return -EFAULT; 367 return 0; 368 case IPC_OLD: 369 { 370 struct msqid_ds tbuf_old; 371 372 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old))) 373 return -EFAULT; 374 375 out->msg_perm.uid = tbuf_old.msg_perm.uid; 376 out->msg_perm.gid = tbuf_old.msg_perm.gid; 377 out->msg_perm.mode = tbuf_old.msg_perm.mode; 378 379 if (tbuf_old.msg_qbytes == 0) 380 out->msg_qbytes = tbuf_old.msg_lqbytes; 381 else 382 out->msg_qbytes = tbuf_old.msg_qbytes; 383 384 return 0; 385 } 386 default: 387 return -EINVAL; 388 } 389 } 390 391 /* 392 * This function handles some msgctl commands which require the rwsem 393 * to be held in write mode. 394 * NOTE: no locks must be held, the rwsem is taken inside this function. 395 */ 396 static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd, 397 struct ipc64_perm *perm, int msg_qbytes) 398 { 399 struct kern_ipc_perm *ipcp; 400 struct msg_queue *msq; 401 int err; 402 403 down_write(&msg_ids(ns).rwsem); 404 rcu_read_lock(); 405 406 ipcp = ipcctl_obtain_check(ns, &msg_ids(ns), msqid, cmd, 407 perm, msg_qbytes); 408 if (IS_ERR(ipcp)) { 409 err = PTR_ERR(ipcp); 410 goto out_unlock1; 411 } 412 413 msq = container_of(ipcp, struct msg_queue, q_perm); 414 415 err = security_msg_queue_msgctl(&msq->q_perm, cmd); 416 if (err) 417 goto out_unlock1; 418 419 switch (cmd) { 420 case IPC_RMID: 421 ipc_lock_object(&msq->q_perm); 422 /* freeque unlocks the ipc object and rcu */ 423 freeque(ns, ipcp); 424 goto out_up; 425 case IPC_SET: 426 { 427 DEFINE_WAKE_Q(wake_q); 428 429 if (msg_qbytes > ns->msg_ctlmnb && 430 !capable(CAP_SYS_RESOURCE)) { 431 err = -EPERM; 432 goto out_unlock1; 433 } 434 435 ipc_lock_object(&msq->q_perm); 436 err = ipc_update_perm(perm, ipcp); 437 if (err) 438 goto out_unlock0; 439 440 msq->q_qbytes = msg_qbytes; 441 442 msq->q_ctime = ktime_get_real_seconds(); 443 /* 444 * Sleeping receivers might be excluded by 445 * stricter permissions. 446 */ 447 expunge_all(msq, -EAGAIN, &wake_q); 448 /* 449 * Sleeping senders might be able to send 450 * due to a larger queue size. 451 */ 452 ss_wakeup(msq, &wake_q, false); 453 ipc_unlock_object(&msq->q_perm); 454 wake_up_q(&wake_q); 455 456 goto out_unlock1; 457 } 458 default: 459 err = -EINVAL; 460 goto out_unlock1; 461 } 462 463 out_unlock0: 464 ipc_unlock_object(&msq->q_perm); 465 out_unlock1: 466 rcu_read_unlock(); 467 out_up: 468 up_write(&msg_ids(ns).rwsem); 469 return err; 470 } 471 472 static int msgctl_info(struct ipc_namespace *ns, int msqid, 473 int cmd, struct msginfo *msginfo) 474 { 475 int err; 476 int max_idx; 477 478 /* 479 * We must not return kernel stack data. 480 * due to padding, it's not enough 481 * to set all member fields. 482 */ 483 err = security_msg_queue_msgctl(NULL, cmd); 484 if (err) 485 return err; 486 487 memset(msginfo, 0, sizeof(*msginfo)); 488 msginfo->msgmni = ns->msg_ctlmni; 489 msginfo->msgmax = ns->msg_ctlmax; 490 msginfo->msgmnb = ns->msg_ctlmnb; 491 msginfo->msgssz = MSGSSZ; 492 msginfo->msgseg = MSGSEG; 493 down_read(&msg_ids(ns).rwsem); 494 if (cmd == MSG_INFO) { 495 msginfo->msgpool = msg_ids(ns).in_use; 496 msginfo->msgmap = atomic_read(&ns->msg_hdrs); 497 msginfo->msgtql = atomic_read(&ns->msg_bytes); 498 } else { 499 msginfo->msgmap = MSGMAP; 500 msginfo->msgpool = MSGPOOL; 501 msginfo->msgtql = MSGTQL; 502 } 503 max_idx = ipc_get_maxidx(&msg_ids(ns)); 504 up_read(&msg_ids(ns).rwsem); 505 return (max_idx < 0) ? 0 : max_idx; 506 } 507 508 static int msgctl_stat(struct ipc_namespace *ns, int msqid, 509 int cmd, struct msqid64_ds *p) 510 { 511 struct msg_queue *msq; 512 int err; 513 514 memset(p, 0, sizeof(*p)); 515 516 rcu_read_lock(); 517 if (cmd == MSG_STAT || cmd == MSG_STAT_ANY) { 518 msq = msq_obtain_object(ns, msqid); 519 if (IS_ERR(msq)) { 520 err = PTR_ERR(msq); 521 goto out_unlock; 522 } 523 } else { /* IPC_STAT */ 524 msq = msq_obtain_object_check(ns, msqid); 525 if (IS_ERR(msq)) { 526 err = PTR_ERR(msq); 527 goto out_unlock; 528 } 529 } 530 531 /* see comment for SHM_STAT_ANY */ 532 if (cmd == MSG_STAT_ANY) 533 audit_ipc_obj(&msq->q_perm); 534 else { 535 err = -EACCES; 536 if (ipcperms(ns, &msq->q_perm, S_IRUGO)) 537 goto out_unlock; 538 } 539 540 err = security_msg_queue_msgctl(&msq->q_perm, cmd); 541 if (err) 542 goto out_unlock; 543 544 ipc_lock_object(&msq->q_perm); 545 546 if (!ipc_valid_object(&msq->q_perm)) { 547 ipc_unlock_object(&msq->q_perm); 548 err = -EIDRM; 549 goto out_unlock; 550 } 551 552 kernel_to_ipc64_perm(&msq->q_perm, &p->msg_perm); 553 p->msg_stime = msq->q_stime; 554 p->msg_rtime = msq->q_rtime; 555 p->msg_ctime = msq->q_ctime; 556 #ifndef CONFIG_64BIT 557 p->msg_stime_high = msq->q_stime >> 32; 558 p->msg_rtime_high = msq->q_rtime >> 32; 559 p->msg_ctime_high = msq->q_ctime >> 32; 560 #endif 561 p->msg_cbytes = msq->q_cbytes; 562 p->msg_qnum = msq->q_qnum; 563 p->msg_qbytes = msq->q_qbytes; 564 p->msg_lspid = pid_vnr(msq->q_lspid); 565 p->msg_lrpid = pid_vnr(msq->q_lrpid); 566 567 if (cmd == IPC_STAT) { 568 /* 569 * As defined in SUS: 570 * Return 0 on success 571 */ 572 err = 0; 573 } else { 574 /* 575 * MSG_STAT and MSG_STAT_ANY (both Linux specific) 576 * Return the full id, including the sequence number 577 */ 578 err = msq->q_perm.id; 579 } 580 581 ipc_unlock_object(&msq->q_perm); 582 out_unlock: 583 rcu_read_unlock(); 584 return err; 585 } 586 587 static long ksys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf, int version) 588 { 589 struct ipc_namespace *ns; 590 struct msqid64_ds msqid64; 591 int err; 592 593 if (msqid < 0 || cmd < 0) 594 return -EINVAL; 595 596 ns = current->nsproxy->ipc_ns; 597 598 switch (cmd) { 599 case IPC_INFO: 600 case MSG_INFO: { 601 struct msginfo msginfo; 602 err = msgctl_info(ns, msqid, cmd, &msginfo); 603 if (err < 0) 604 return err; 605 if (copy_to_user(buf, &msginfo, sizeof(struct msginfo))) 606 err = -EFAULT; 607 return err; 608 } 609 case MSG_STAT: /* msqid is an index rather than a msg queue id */ 610 case MSG_STAT_ANY: 611 case IPC_STAT: 612 err = msgctl_stat(ns, msqid, cmd, &msqid64); 613 if (err < 0) 614 return err; 615 if (copy_msqid_to_user(buf, &msqid64, version)) 616 err = -EFAULT; 617 return err; 618 case IPC_SET: 619 if (copy_msqid_from_user(&msqid64, buf, version)) 620 return -EFAULT; 621 return msgctl_down(ns, msqid, cmd, &msqid64.msg_perm, 622 msqid64.msg_qbytes); 623 case IPC_RMID: 624 return msgctl_down(ns, msqid, cmd, NULL, 0); 625 default: 626 return -EINVAL; 627 } 628 } 629 630 SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf) 631 { 632 return ksys_msgctl(msqid, cmd, buf, IPC_64); 633 } 634 635 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION 636 long ksys_old_msgctl(int msqid, int cmd, struct msqid_ds __user *buf) 637 { 638 int version = ipc_parse_version(&cmd); 639 640 return ksys_msgctl(msqid, cmd, buf, version); 641 } 642 643 SYSCALL_DEFINE3(old_msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf) 644 { 645 return ksys_old_msgctl(msqid, cmd, buf); 646 } 647 #endif 648 649 #ifdef CONFIG_COMPAT 650 651 struct compat_msqid_ds { 652 struct compat_ipc_perm msg_perm; 653 compat_uptr_t msg_first; 654 compat_uptr_t msg_last; 655 old_time32_t msg_stime; 656 old_time32_t msg_rtime; 657 old_time32_t msg_ctime; 658 compat_ulong_t msg_lcbytes; 659 compat_ulong_t msg_lqbytes; 660 unsigned short msg_cbytes; 661 unsigned short msg_qnum; 662 unsigned short msg_qbytes; 663 compat_ipc_pid_t msg_lspid; 664 compat_ipc_pid_t msg_lrpid; 665 }; 666 667 static int copy_compat_msqid_from_user(struct msqid64_ds *out, void __user *buf, 668 int version) 669 { 670 memset(out, 0, sizeof(*out)); 671 if (version == IPC_64) { 672 struct compat_msqid64_ds __user *p = buf; 673 if (get_compat_ipc64_perm(&out->msg_perm, &p->msg_perm)) 674 return -EFAULT; 675 if (get_user(out->msg_qbytes, &p->msg_qbytes)) 676 return -EFAULT; 677 } else { 678 struct compat_msqid_ds __user *p = buf; 679 if (get_compat_ipc_perm(&out->msg_perm, &p->msg_perm)) 680 return -EFAULT; 681 if (get_user(out->msg_qbytes, &p->msg_qbytes)) 682 return -EFAULT; 683 } 684 return 0; 685 } 686 687 static int copy_compat_msqid_to_user(void __user *buf, struct msqid64_ds *in, 688 int version) 689 { 690 if (version == IPC_64) { 691 struct compat_msqid64_ds v; 692 memset(&v, 0, sizeof(v)); 693 to_compat_ipc64_perm(&v.msg_perm, &in->msg_perm); 694 v.msg_stime = lower_32_bits(in->msg_stime); 695 v.msg_stime_high = upper_32_bits(in->msg_stime); 696 v.msg_rtime = lower_32_bits(in->msg_rtime); 697 v.msg_rtime_high = upper_32_bits(in->msg_rtime); 698 v.msg_ctime = lower_32_bits(in->msg_ctime); 699 v.msg_ctime_high = upper_32_bits(in->msg_ctime); 700 v.msg_cbytes = in->msg_cbytes; 701 v.msg_qnum = in->msg_qnum; 702 v.msg_qbytes = in->msg_qbytes; 703 v.msg_lspid = in->msg_lspid; 704 v.msg_lrpid = in->msg_lrpid; 705 return copy_to_user(buf, &v, sizeof(v)); 706 } else { 707 struct compat_msqid_ds v; 708 memset(&v, 0, sizeof(v)); 709 to_compat_ipc_perm(&v.msg_perm, &in->msg_perm); 710 v.msg_stime = in->msg_stime; 711 v.msg_rtime = in->msg_rtime; 712 v.msg_ctime = in->msg_ctime; 713 v.msg_cbytes = in->msg_cbytes; 714 v.msg_qnum = in->msg_qnum; 715 v.msg_qbytes = in->msg_qbytes; 716 v.msg_lspid = in->msg_lspid; 717 v.msg_lrpid = in->msg_lrpid; 718 return copy_to_user(buf, &v, sizeof(v)); 719 } 720 } 721 722 static long compat_ksys_msgctl(int msqid, int cmd, void __user *uptr, int version) 723 { 724 struct ipc_namespace *ns; 725 int err; 726 struct msqid64_ds msqid64; 727 728 ns = current->nsproxy->ipc_ns; 729 730 if (msqid < 0 || cmd < 0) 731 return -EINVAL; 732 733 switch (cmd & (~IPC_64)) { 734 case IPC_INFO: 735 case MSG_INFO: { 736 struct msginfo msginfo; 737 err = msgctl_info(ns, msqid, cmd, &msginfo); 738 if (err < 0) 739 return err; 740 if (copy_to_user(uptr, &msginfo, sizeof(struct msginfo))) 741 err = -EFAULT; 742 return err; 743 } 744 case IPC_STAT: 745 case MSG_STAT: 746 case MSG_STAT_ANY: 747 err = msgctl_stat(ns, msqid, cmd, &msqid64); 748 if (err < 0) 749 return err; 750 if (copy_compat_msqid_to_user(uptr, &msqid64, version)) 751 err = -EFAULT; 752 return err; 753 case IPC_SET: 754 if (copy_compat_msqid_from_user(&msqid64, uptr, version)) 755 return -EFAULT; 756 return msgctl_down(ns, msqid, cmd, &msqid64.msg_perm, msqid64.msg_qbytes); 757 case IPC_RMID: 758 return msgctl_down(ns, msqid, cmd, NULL, 0); 759 default: 760 return -EINVAL; 761 } 762 } 763 764 COMPAT_SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, void __user *, uptr) 765 { 766 return compat_ksys_msgctl(msqid, cmd, uptr, IPC_64); 767 } 768 769 #ifdef CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION 770 long compat_ksys_old_msgctl(int msqid, int cmd, void __user *uptr) 771 { 772 int version = compat_ipc_parse_version(&cmd); 773 774 return compat_ksys_msgctl(msqid, cmd, uptr, version); 775 } 776 777 COMPAT_SYSCALL_DEFINE3(old_msgctl, int, msqid, int, cmd, void __user *, uptr) 778 { 779 return compat_ksys_old_msgctl(msqid, cmd, uptr); 780 } 781 #endif 782 #endif 783 784 static int testmsg(struct msg_msg *msg, long type, int mode) 785 { 786 switch (mode) { 787 case SEARCH_ANY: 788 case SEARCH_NUMBER: 789 return 1; 790 case SEARCH_LESSEQUAL: 791 if (msg->m_type <= type) 792 return 1; 793 break; 794 case SEARCH_EQUAL: 795 if (msg->m_type == type) 796 return 1; 797 break; 798 case SEARCH_NOTEQUAL: 799 if (msg->m_type != type) 800 return 1; 801 break; 802 } 803 return 0; 804 } 805 806 static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg, 807 struct wake_q_head *wake_q) 808 { 809 struct msg_receiver *msr, *t; 810 811 list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) { 812 if (testmsg(msg, msr->r_msgtype, msr->r_mode) && 813 !security_msg_queue_msgrcv(&msq->q_perm, msg, msr->r_tsk, 814 msr->r_msgtype, msr->r_mode)) { 815 816 list_del(&msr->r_list); 817 if (msr->r_maxsize < msg->m_ts) { 818 wake_q_add(wake_q, msr->r_tsk); 819 820 /* See expunge_all regarding memory barrier */ 821 smp_store_release(&msr->r_msg, ERR_PTR(-E2BIG)); 822 } else { 823 ipc_update_pid(&msq->q_lrpid, task_pid(msr->r_tsk)); 824 msq->q_rtime = ktime_get_real_seconds(); 825 826 wake_q_add(wake_q, msr->r_tsk); 827 828 /* See expunge_all regarding memory barrier */ 829 smp_store_release(&msr->r_msg, msg); 830 return 1; 831 } 832 } 833 } 834 835 return 0; 836 } 837 838 static long do_msgsnd(int msqid, long mtype, void __user *mtext, 839 size_t msgsz, int msgflg) 840 { 841 struct msg_queue *msq; 842 struct msg_msg *msg; 843 int err; 844 struct ipc_namespace *ns; 845 DEFINE_WAKE_Q(wake_q); 846 847 ns = current->nsproxy->ipc_ns; 848 849 if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0) 850 return -EINVAL; 851 if (mtype < 1) 852 return -EINVAL; 853 854 msg = load_msg(mtext, msgsz); 855 if (IS_ERR(msg)) 856 return PTR_ERR(msg); 857 858 msg->m_type = mtype; 859 msg->m_ts = msgsz; 860 861 rcu_read_lock(); 862 msq = msq_obtain_object_check(ns, msqid); 863 if (IS_ERR(msq)) { 864 err = PTR_ERR(msq); 865 goto out_unlock1; 866 } 867 868 ipc_lock_object(&msq->q_perm); 869 870 for (;;) { 871 struct msg_sender s; 872 873 err = -EACCES; 874 if (ipcperms(ns, &msq->q_perm, S_IWUGO)) 875 goto out_unlock0; 876 877 /* raced with RMID? */ 878 if (!ipc_valid_object(&msq->q_perm)) { 879 err = -EIDRM; 880 goto out_unlock0; 881 } 882 883 err = security_msg_queue_msgsnd(&msq->q_perm, msg, msgflg); 884 if (err) 885 goto out_unlock0; 886 887 if (msg_fits_inqueue(msq, msgsz)) 888 break; 889 890 /* queue full, wait: */ 891 if (msgflg & IPC_NOWAIT) { 892 err = -EAGAIN; 893 goto out_unlock0; 894 } 895 896 /* enqueue the sender and prepare to block */ 897 ss_add(msq, &s, msgsz); 898 899 if (!ipc_rcu_getref(&msq->q_perm)) { 900 err = -EIDRM; 901 goto out_unlock0; 902 } 903 904 ipc_unlock_object(&msq->q_perm); 905 rcu_read_unlock(); 906 schedule(); 907 908 rcu_read_lock(); 909 ipc_lock_object(&msq->q_perm); 910 911 ipc_rcu_putref(&msq->q_perm, msg_rcu_free); 912 /* raced with RMID? */ 913 if (!ipc_valid_object(&msq->q_perm)) { 914 err = -EIDRM; 915 goto out_unlock0; 916 } 917 ss_del(&s); 918 919 if (signal_pending(current)) { 920 err = -ERESTARTNOHAND; 921 goto out_unlock0; 922 } 923 924 } 925 926 ipc_update_pid(&msq->q_lspid, task_tgid(current)); 927 msq->q_stime = ktime_get_real_seconds(); 928 929 if (!pipelined_send(msq, msg, &wake_q)) { 930 /* no one is waiting for this message, enqueue it */ 931 list_add_tail(&msg->m_list, &msq->q_messages); 932 msq->q_cbytes += msgsz; 933 msq->q_qnum++; 934 atomic_add(msgsz, &ns->msg_bytes); 935 atomic_inc(&ns->msg_hdrs); 936 } 937 938 err = 0; 939 msg = NULL; 940 941 out_unlock0: 942 ipc_unlock_object(&msq->q_perm); 943 wake_up_q(&wake_q); 944 out_unlock1: 945 rcu_read_unlock(); 946 if (msg != NULL) 947 free_msg(msg); 948 return err; 949 } 950 951 long ksys_msgsnd(int msqid, struct msgbuf __user *msgp, size_t msgsz, 952 int msgflg) 953 { 954 long mtype; 955 956 if (get_user(mtype, &msgp->mtype)) 957 return -EFAULT; 958 return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg); 959 } 960 961 SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz, 962 int, msgflg) 963 { 964 return ksys_msgsnd(msqid, msgp, msgsz, msgflg); 965 } 966 967 #ifdef CONFIG_COMPAT 968 969 struct compat_msgbuf { 970 compat_long_t mtype; 971 char mtext[1]; 972 }; 973 974 long compat_ksys_msgsnd(int msqid, compat_uptr_t msgp, 975 compat_ssize_t msgsz, int msgflg) 976 { 977 struct compat_msgbuf __user *up = compat_ptr(msgp); 978 compat_long_t mtype; 979 980 if (get_user(mtype, &up->mtype)) 981 return -EFAULT; 982 return do_msgsnd(msqid, mtype, up->mtext, (ssize_t)msgsz, msgflg); 983 } 984 985 COMPAT_SYSCALL_DEFINE4(msgsnd, int, msqid, compat_uptr_t, msgp, 986 compat_ssize_t, msgsz, int, msgflg) 987 { 988 return compat_ksys_msgsnd(msqid, msgp, msgsz, msgflg); 989 } 990 #endif 991 992 static inline int convert_mode(long *msgtyp, int msgflg) 993 { 994 if (msgflg & MSG_COPY) 995 return SEARCH_NUMBER; 996 /* 997 * find message of correct type. 998 * msgtyp = 0 => get first. 999 * msgtyp > 0 => get first message of matching type. 1000 * msgtyp < 0 => get message with least type must be < abs(msgtype). 1001 */ 1002 if (*msgtyp == 0) 1003 return SEARCH_ANY; 1004 if (*msgtyp < 0) { 1005 if (*msgtyp == LONG_MIN) /* -LONG_MIN is undefined */ 1006 *msgtyp = LONG_MAX; 1007 else 1008 *msgtyp = -*msgtyp; 1009 return SEARCH_LESSEQUAL; 1010 } 1011 if (msgflg & MSG_EXCEPT) 1012 return SEARCH_NOTEQUAL; 1013 return SEARCH_EQUAL; 1014 } 1015 1016 static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz) 1017 { 1018 struct msgbuf __user *msgp = dest; 1019 size_t msgsz; 1020 1021 if (put_user(msg->m_type, &msgp->mtype)) 1022 return -EFAULT; 1023 1024 msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz; 1025 if (store_msg(msgp->mtext, msg, msgsz)) 1026 return -EFAULT; 1027 return msgsz; 1028 } 1029 1030 #ifdef CONFIG_CHECKPOINT_RESTORE 1031 /* 1032 * This function creates new kernel message structure, large enough to store 1033 * bufsz message bytes. 1034 */ 1035 static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz) 1036 { 1037 struct msg_msg *copy; 1038 1039 /* 1040 * Create dummy message to copy real message to. 1041 */ 1042 copy = load_msg(buf, bufsz); 1043 if (!IS_ERR(copy)) 1044 copy->m_ts = bufsz; 1045 return copy; 1046 } 1047 1048 static inline void free_copy(struct msg_msg *copy) 1049 { 1050 if (copy) 1051 free_msg(copy); 1052 } 1053 #else 1054 static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz) 1055 { 1056 return ERR_PTR(-ENOSYS); 1057 } 1058 1059 static inline void free_copy(struct msg_msg *copy) 1060 { 1061 } 1062 #endif 1063 1064 static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode) 1065 { 1066 struct msg_msg *msg, *found = NULL; 1067 long count = 0; 1068 1069 list_for_each_entry(msg, &msq->q_messages, m_list) { 1070 if (testmsg(msg, *msgtyp, mode) && 1071 !security_msg_queue_msgrcv(&msq->q_perm, msg, current, 1072 *msgtyp, mode)) { 1073 if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) { 1074 *msgtyp = msg->m_type - 1; 1075 found = msg; 1076 } else if (mode == SEARCH_NUMBER) { 1077 if (*msgtyp == count) 1078 return msg; 1079 } else 1080 return msg; 1081 count++; 1082 } 1083 } 1084 1085 return found ?: ERR_PTR(-EAGAIN); 1086 } 1087 1088 static long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg, 1089 long (*msg_handler)(void __user *, struct msg_msg *, size_t)) 1090 { 1091 int mode; 1092 struct msg_queue *msq; 1093 struct ipc_namespace *ns; 1094 struct msg_msg *msg, *copy = NULL; 1095 DEFINE_WAKE_Q(wake_q); 1096 1097 ns = current->nsproxy->ipc_ns; 1098 1099 if (msqid < 0 || (long) bufsz < 0) 1100 return -EINVAL; 1101 1102 if (msgflg & MSG_COPY) { 1103 if ((msgflg & MSG_EXCEPT) || !(msgflg & IPC_NOWAIT)) 1104 return -EINVAL; 1105 copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax)); 1106 if (IS_ERR(copy)) 1107 return PTR_ERR(copy); 1108 } 1109 mode = convert_mode(&msgtyp, msgflg); 1110 1111 rcu_read_lock(); 1112 msq = msq_obtain_object_check(ns, msqid); 1113 if (IS_ERR(msq)) { 1114 rcu_read_unlock(); 1115 free_copy(copy); 1116 return PTR_ERR(msq); 1117 } 1118 1119 for (;;) { 1120 struct msg_receiver msr_d; 1121 1122 msg = ERR_PTR(-EACCES); 1123 if (ipcperms(ns, &msq->q_perm, S_IRUGO)) 1124 goto out_unlock1; 1125 1126 ipc_lock_object(&msq->q_perm); 1127 1128 /* raced with RMID? */ 1129 if (!ipc_valid_object(&msq->q_perm)) { 1130 msg = ERR_PTR(-EIDRM); 1131 goto out_unlock0; 1132 } 1133 1134 msg = find_msg(msq, &msgtyp, mode); 1135 if (!IS_ERR(msg)) { 1136 /* 1137 * Found a suitable message. 1138 * Unlink it from the queue. 1139 */ 1140 if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) { 1141 msg = ERR_PTR(-E2BIG); 1142 goto out_unlock0; 1143 } 1144 /* 1145 * If we are copying, then do not unlink message and do 1146 * not update queue parameters. 1147 */ 1148 if (msgflg & MSG_COPY) { 1149 msg = copy_msg(msg, copy); 1150 goto out_unlock0; 1151 } 1152 1153 list_del(&msg->m_list); 1154 msq->q_qnum--; 1155 msq->q_rtime = ktime_get_real_seconds(); 1156 ipc_update_pid(&msq->q_lrpid, task_tgid(current)); 1157 msq->q_cbytes -= msg->m_ts; 1158 atomic_sub(msg->m_ts, &ns->msg_bytes); 1159 atomic_dec(&ns->msg_hdrs); 1160 ss_wakeup(msq, &wake_q, false); 1161 1162 goto out_unlock0; 1163 } 1164 1165 /* No message waiting. Wait for a message */ 1166 if (msgflg & IPC_NOWAIT) { 1167 msg = ERR_PTR(-ENOMSG); 1168 goto out_unlock0; 1169 } 1170 1171 list_add_tail(&msr_d.r_list, &msq->q_receivers); 1172 msr_d.r_tsk = current; 1173 msr_d.r_msgtype = msgtyp; 1174 msr_d.r_mode = mode; 1175 if (msgflg & MSG_NOERROR) 1176 msr_d.r_maxsize = INT_MAX; 1177 else 1178 msr_d.r_maxsize = bufsz; 1179 1180 /* memory barrier not require due to ipc_lock_object() */ 1181 WRITE_ONCE(msr_d.r_msg, ERR_PTR(-EAGAIN)); 1182 1183 /* memory barrier not required, we own ipc_lock_object() */ 1184 __set_current_state(TASK_INTERRUPTIBLE); 1185 1186 ipc_unlock_object(&msq->q_perm); 1187 rcu_read_unlock(); 1188 schedule(); 1189 1190 /* 1191 * Lockless receive, part 1: 1192 * We don't hold a reference to the queue and getting a 1193 * reference would defeat the idea of a lockless operation, 1194 * thus the code relies on rcu to guarantee the existence of 1195 * msq: 1196 * Prior to destruction, expunge_all(-EIRDM) changes r_msg. 1197 * Thus if r_msg is -EAGAIN, then the queue not yet destroyed. 1198 */ 1199 rcu_read_lock(); 1200 1201 /* 1202 * Lockless receive, part 2: 1203 * The work in pipelined_send() and expunge_all(): 1204 * - Set pointer to message 1205 * - Queue the receiver task for later wakeup 1206 * - Wake up the process after the lock is dropped. 1207 * 1208 * Should the process wake up before this wakeup (due to a 1209 * signal) it will either see the message and continue ... 1210 */ 1211 msg = READ_ONCE(msr_d.r_msg); 1212 if (msg != ERR_PTR(-EAGAIN)) { 1213 /* see MSG_BARRIER for purpose/pairing */ 1214 smp_acquire__after_ctrl_dep(); 1215 1216 goto out_unlock1; 1217 } 1218 1219 /* 1220 * ... or see -EAGAIN, acquire the lock to check the message 1221 * again. 1222 */ 1223 ipc_lock_object(&msq->q_perm); 1224 1225 msg = READ_ONCE(msr_d.r_msg); 1226 if (msg != ERR_PTR(-EAGAIN)) 1227 goto out_unlock0; 1228 1229 list_del(&msr_d.r_list); 1230 if (signal_pending(current)) { 1231 msg = ERR_PTR(-ERESTARTNOHAND); 1232 goto out_unlock0; 1233 } 1234 1235 ipc_unlock_object(&msq->q_perm); 1236 } 1237 1238 out_unlock0: 1239 ipc_unlock_object(&msq->q_perm); 1240 wake_up_q(&wake_q); 1241 out_unlock1: 1242 rcu_read_unlock(); 1243 if (IS_ERR(msg)) { 1244 free_copy(copy); 1245 return PTR_ERR(msg); 1246 } 1247 1248 bufsz = msg_handler(buf, msg, bufsz); 1249 free_msg(msg); 1250 1251 return bufsz; 1252 } 1253 1254 long ksys_msgrcv(int msqid, struct msgbuf __user *msgp, size_t msgsz, 1255 long msgtyp, int msgflg) 1256 { 1257 return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill); 1258 } 1259 1260 SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz, 1261 long, msgtyp, int, msgflg) 1262 { 1263 return ksys_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg); 1264 } 1265 1266 #ifdef CONFIG_COMPAT 1267 static long compat_do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz) 1268 { 1269 struct compat_msgbuf __user *msgp = dest; 1270 size_t msgsz; 1271 1272 if (put_user(msg->m_type, &msgp->mtype)) 1273 return -EFAULT; 1274 1275 msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz; 1276 if (store_msg(msgp->mtext, msg, msgsz)) 1277 return -EFAULT; 1278 return msgsz; 1279 } 1280 1281 long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz, 1282 compat_long_t msgtyp, int msgflg) 1283 { 1284 return do_msgrcv(msqid, compat_ptr(msgp), (ssize_t)msgsz, (long)msgtyp, 1285 msgflg, compat_do_msg_fill); 1286 } 1287 1288 COMPAT_SYSCALL_DEFINE5(msgrcv, int, msqid, compat_uptr_t, msgp, 1289 compat_ssize_t, msgsz, compat_long_t, msgtyp, 1290 int, msgflg) 1291 { 1292 return compat_ksys_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg); 1293 } 1294 #endif 1295 1296 void msg_init_ns(struct ipc_namespace *ns) 1297 { 1298 ns->msg_ctlmax = MSGMAX; 1299 ns->msg_ctlmnb = MSGMNB; 1300 ns->msg_ctlmni = MSGMNI; 1301 1302 atomic_set(&ns->msg_bytes, 0); 1303 atomic_set(&ns->msg_hdrs, 0); 1304 ipc_init_ids(&ns->ids[IPC_MSG_IDS]); 1305 } 1306 1307 #ifdef CONFIG_IPC_NS 1308 void msg_exit_ns(struct ipc_namespace *ns) 1309 { 1310 free_ipcs(ns, &msg_ids(ns), freeque); 1311 idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr); 1312 rhashtable_destroy(&ns->ids[IPC_MSG_IDS].key_ht); 1313 } 1314 #endif 1315 1316 #ifdef CONFIG_PROC_FS 1317 static int sysvipc_msg_proc_show(struct seq_file *s, void *it) 1318 { 1319 struct pid_namespace *pid_ns = ipc_seq_pid_ns(s); 1320 struct user_namespace *user_ns = seq_user_ns(s); 1321 struct kern_ipc_perm *ipcp = it; 1322 struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm); 1323 1324 seq_printf(s, 1325 "%10d %10d %4o %10lu %10lu %5u %5u %5u %5u %5u %5u %10llu %10llu %10llu\n", 1326 msq->q_perm.key, 1327 msq->q_perm.id, 1328 msq->q_perm.mode, 1329 msq->q_cbytes, 1330 msq->q_qnum, 1331 pid_nr_ns(msq->q_lspid, pid_ns), 1332 pid_nr_ns(msq->q_lrpid, pid_ns), 1333 from_kuid_munged(user_ns, msq->q_perm.uid), 1334 from_kgid_munged(user_ns, msq->q_perm.gid), 1335 from_kuid_munged(user_ns, msq->q_perm.cuid), 1336 from_kgid_munged(user_ns, msq->q_perm.cgid), 1337 msq->q_stime, 1338 msq->q_rtime, 1339 msq->q_ctime); 1340 1341 return 0; 1342 } 1343 #endif 1344 1345 void __init msg_init(void) 1346 { 1347 msg_init_ns(&init_ipc_ns); 1348 1349 ipc_init_proc_interface("sysvipc/msg", 1350 " key msqid perms cbytes qnum lspid lrpid uid gid cuid cgid stime rtime ctime\n", 1351 IPC_MSG_IDS, sysvipc_msg_proc_show); 1352 } 1353