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 <[email protected]> 13 * 14 * mostly rewritten, threaded and wake-one semantics added 15 * MSGMAX limit removed, sysctl's added 16 * (c) 1999 Manfred Spraul <[email protected]> 17 * 18 * support for audit of ipc object properties and permission changes 19 * Dustin Kirkland <[email protected]> 20 * 21 * namespaces support 22 * OpenVZ, SWsoft Inc. 23 * Pavel Emelianov <[email protected]> 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 msqid64_ds *msqid64) 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 &msqid64->msg_perm, msqid64->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 (msqid64->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(&msqid64->msg_perm, ipcp); 437 if (err) 438 goto out_unlock0; 439 440 msq->q_qbytes = msqid64->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 /* fallthru */ 622 case IPC_RMID: 623 return msgctl_down(ns, msqid, cmd, &msqid64); 624 default: 625 return -EINVAL; 626 } 627 } 628 629 SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf) 630 { 631 return ksys_msgctl(msqid, cmd, buf, IPC_64); 632 } 633 634 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION 635 long ksys_old_msgctl(int msqid, int cmd, struct msqid_ds __user *buf) 636 { 637 int version = ipc_parse_version(&cmd); 638 639 return ksys_msgctl(msqid, cmd, buf, version); 640 } 641 642 SYSCALL_DEFINE3(old_msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf) 643 { 644 return ksys_old_msgctl(msqid, cmd, buf); 645 } 646 #endif 647 648 #ifdef CONFIG_COMPAT 649 650 struct compat_msqid_ds { 651 struct compat_ipc_perm msg_perm; 652 compat_uptr_t msg_first; 653 compat_uptr_t msg_last; 654 old_time32_t msg_stime; 655 old_time32_t msg_rtime; 656 old_time32_t msg_ctime; 657 compat_ulong_t msg_lcbytes; 658 compat_ulong_t msg_lqbytes; 659 unsigned short msg_cbytes; 660 unsigned short msg_qnum; 661 unsigned short msg_qbytes; 662 compat_ipc_pid_t msg_lspid; 663 compat_ipc_pid_t msg_lrpid; 664 }; 665 666 static int copy_compat_msqid_from_user(struct msqid64_ds *out, void __user *buf, 667 int version) 668 { 669 memset(out, 0, sizeof(*out)); 670 if (version == IPC_64) { 671 struct compat_msqid64_ds __user *p = buf; 672 if (get_compat_ipc64_perm(&out->msg_perm, &p->msg_perm)) 673 return -EFAULT; 674 if (get_user(out->msg_qbytes, &p->msg_qbytes)) 675 return -EFAULT; 676 } else { 677 struct compat_msqid_ds __user *p = buf; 678 if (get_compat_ipc_perm(&out->msg_perm, &p->msg_perm)) 679 return -EFAULT; 680 if (get_user(out->msg_qbytes, &p->msg_qbytes)) 681 return -EFAULT; 682 } 683 return 0; 684 } 685 686 static int copy_compat_msqid_to_user(void __user *buf, struct msqid64_ds *in, 687 int version) 688 { 689 if (version == IPC_64) { 690 struct compat_msqid64_ds v; 691 memset(&v, 0, sizeof(v)); 692 to_compat_ipc64_perm(&v.msg_perm, &in->msg_perm); 693 v.msg_stime = lower_32_bits(in->msg_stime); 694 v.msg_stime_high = upper_32_bits(in->msg_stime); 695 v.msg_rtime = lower_32_bits(in->msg_rtime); 696 v.msg_rtime_high = upper_32_bits(in->msg_rtime); 697 v.msg_ctime = lower_32_bits(in->msg_ctime); 698 v.msg_ctime_high = upper_32_bits(in->msg_ctime); 699 v.msg_cbytes = in->msg_cbytes; 700 v.msg_qnum = in->msg_qnum; 701 v.msg_qbytes = in->msg_qbytes; 702 v.msg_lspid = in->msg_lspid; 703 v.msg_lrpid = in->msg_lrpid; 704 return copy_to_user(buf, &v, sizeof(v)); 705 } else { 706 struct compat_msqid_ds v; 707 memset(&v, 0, sizeof(v)); 708 to_compat_ipc_perm(&v.msg_perm, &in->msg_perm); 709 v.msg_stime = in->msg_stime; 710 v.msg_rtime = in->msg_rtime; 711 v.msg_ctime = in->msg_ctime; 712 v.msg_cbytes = in->msg_cbytes; 713 v.msg_qnum = in->msg_qnum; 714 v.msg_qbytes = in->msg_qbytes; 715 v.msg_lspid = in->msg_lspid; 716 v.msg_lrpid = in->msg_lrpid; 717 return copy_to_user(buf, &v, sizeof(v)); 718 } 719 } 720 721 static long compat_ksys_msgctl(int msqid, int cmd, void __user *uptr, int version) 722 { 723 struct ipc_namespace *ns; 724 int err; 725 struct msqid64_ds msqid64; 726 727 ns = current->nsproxy->ipc_ns; 728 729 if (msqid < 0 || cmd < 0) 730 return -EINVAL; 731 732 switch (cmd & (~IPC_64)) { 733 case IPC_INFO: 734 case MSG_INFO: { 735 struct msginfo msginfo; 736 err = msgctl_info(ns, msqid, cmd, &msginfo); 737 if (err < 0) 738 return err; 739 if (copy_to_user(uptr, &msginfo, sizeof(struct msginfo))) 740 err = -EFAULT; 741 return err; 742 } 743 case IPC_STAT: 744 case MSG_STAT: 745 case MSG_STAT_ANY: 746 err = msgctl_stat(ns, msqid, cmd, &msqid64); 747 if (err < 0) 748 return err; 749 if (copy_compat_msqid_to_user(uptr, &msqid64, version)) 750 err = -EFAULT; 751 return err; 752 case IPC_SET: 753 if (copy_compat_msqid_from_user(&msqid64, uptr, version)) 754 return -EFAULT; 755 /* fallthru */ 756 case IPC_RMID: 757 return msgctl_down(ns, msqid, cmd, &msqid64); 758 default: 759 return -EINVAL; 760 } 761 } 762 763 COMPAT_SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, void __user *, uptr) 764 { 765 return compat_ksys_msgctl(msqid, cmd, uptr, IPC_64); 766 } 767 768 #ifdef CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION 769 long compat_ksys_old_msgctl(int msqid, int cmd, void __user *uptr) 770 { 771 int version = compat_ipc_parse_version(&cmd); 772 773 return compat_ksys_msgctl(msqid, cmd, uptr, version); 774 } 775 776 COMPAT_SYSCALL_DEFINE3(old_msgctl, int, msqid, int, cmd, void __user *, uptr) 777 { 778 return compat_ksys_old_msgctl(msqid, cmd, uptr); 779 } 780 #endif 781 #endif 782 783 static int testmsg(struct msg_msg *msg, long type, int mode) 784 { 785 switch (mode) { 786 case SEARCH_ANY: 787 case SEARCH_NUMBER: 788 return 1; 789 case SEARCH_LESSEQUAL: 790 if (msg->m_type <= type) 791 return 1; 792 break; 793 case SEARCH_EQUAL: 794 if (msg->m_type == type) 795 return 1; 796 break; 797 case SEARCH_NOTEQUAL: 798 if (msg->m_type != type) 799 return 1; 800 break; 801 } 802 return 0; 803 } 804 805 static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg, 806 struct wake_q_head *wake_q) 807 { 808 struct msg_receiver *msr, *t; 809 810 list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) { 811 if (testmsg(msg, msr->r_msgtype, msr->r_mode) && 812 !security_msg_queue_msgrcv(&msq->q_perm, msg, msr->r_tsk, 813 msr->r_msgtype, msr->r_mode)) { 814 815 list_del(&msr->r_list); 816 if (msr->r_maxsize < msg->m_ts) { 817 wake_q_add(wake_q, msr->r_tsk); 818 819 /* See expunge_all regarding memory barrier */ 820 smp_store_release(&msr->r_msg, ERR_PTR(-E2BIG)); 821 } else { 822 ipc_update_pid(&msq->q_lrpid, task_pid(msr->r_tsk)); 823 msq->q_rtime = ktime_get_real_seconds(); 824 825 wake_q_add(wake_q, msr->r_tsk); 826 827 /* See expunge_all regarding memory barrier */ 828 smp_store_release(&msr->r_msg, msg); 829 return 1; 830 } 831 } 832 } 833 834 return 0; 835 } 836 837 static long do_msgsnd(int msqid, long mtype, void __user *mtext, 838 size_t msgsz, int msgflg) 839 { 840 struct msg_queue *msq; 841 struct msg_msg *msg; 842 int err; 843 struct ipc_namespace *ns; 844 DEFINE_WAKE_Q(wake_q); 845 846 ns = current->nsproxy->ipc_ns; 847 848 if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0) 849 return -EINVAL; 850 if (mtype < 1) 851 return -EINVAL; 852 853 msg = load_msg(mtext, msgsz); 854 if (IS_ERR(msg)) 855 return PTR_ERR(msg); 856 857 msg->m_type = mtype; 858 msg->m_ts = msgsz; 859 860 rcu_read_lock(); 861 msq = msq_obtain_object_check(ns, msqid); 862 if (IS_ERR(msq)) { 863 err = PTR_ERR(msq); 864 goto out_unlock1; 865 } 866 867 ipc_lock_object(&msq->q_perm); 868 869 for (;;) { 870 struct msg_sender s; 871 872 err = -EACCES; 873 if (ipcperms(ns, &msq->q_perm, S_IWUGO)) 874 goto out_unlock0; 875 876 /* raced with RMID? */ 877 if (!ipc_valid_object(&msq->q_perm)) { 878 err = -EIDRM; 879 goto out_unlock0; 880 } 881 882 err = security_msg_queue_msgsnd(&msq->q_perm, msg, msgflg); 883 if (err) 884 goto out_unlock0; 885 886 if (msg_fits_inqueue(msq, msgsz)) 887 break; 888 889 /* queue full, wait: */ 890 if (msgflg & IPC_NOWAIT) { 891 err = -EAGAIN; 892 goto out_unlock0; 893 } 894 895 /* enqueue the sender and prepare to block */ 896 ss_add(msq, &s, msgsz); 897 898 if (!ipc_rcu_getref(&msq->q_perm)) { 899 err = -EIDRM; 900 goto out_unlock0; 901 } 902 903 ipc_unlock_object(&msq->q_perm); 904 rcu_read_unlock(); 905 schedule(); 906 907 rcu_read_lock(); 908 ipc_lock_object(&msq->q_perm); 909 910 ipc_rcu_putref(&msq->q_perm, msg_rcu_free); 911 /* raced with RMID? */ 912 if (!ipc_valid_object(&msq->q_perm)) { 913 err = -EIDRM; 914 goto out_unlock0; 915 } 916 ss_del(&s); 917 918 if (signal_pending(current)) { 919 err = -ERESTARTNOHAND; 920 goto out_unlock0; 921 } 922 923 } 924 925 ipc_update_pid(&msq->q_lspid, task_tgid(current)); 926 msq->q_stime = ktime_get_real_seconds(); 927 928 if (!pipelined_send(msq, msg, &wake_q)) { 929 /* no one is waiting for this message, enqueue it */ 930 list_add_tail(&msg->m_list, &msq->q_messages); 931 msq->q_cbytes += msgsz; 932 msq->q_qnum++; 933 atomic_add(msgsz, &ns->msg_bytes); 934 atomic_inc(&ns->msg_hdrs); 935 } 936 937 err = 0; 938 msg = NULL; 939 940 out_unlock0: 941 ipc_unlock_object(&msq->q_perm); 942 wake_up_q(&wake_q); 943 out_unlock1: 944 rcu_read_unlock(); 945 if (msg != NULL) 946 free_msg(msg); 947 return err; 948 } 949 950 long ksys_msgsnd(int msqid, struct msgbuf __user *msgp, size_t msgsz, 951 int msgflg) 952 { 953 long mtype; 954 955 if (get_user(mtype, &msgp->mtype)) 956 return -EFAULT; 957 return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg); 958 } 959 960 SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz, 961 int, msgflg) 962 { 963 return ksys_msgsnd(msqid, msgp, msgsz, msgflg); 964 } 965 966 #ifdef CONFIG_COMPAT 967 968 struct compat_msgbuf { 969 compat_long_t mtype; 970 char mtext[1]; 971 }; 972 973 long compat_ksys_msgsnd(int msqid, compat_uptr_t msgp, 974 compat_ssize_t msgsz, int msgflg) 975 { 976 struct compat_msgbuf __user *up = compat_ptr(msgp); 977 compat_long_t mtype; 978 979 if (get_user(mtype, &up->mtype)) 980 return -EFAULT; 981 return do_msgsnd(msqid, mtype, up->mtext, (ssize_t)msgsz, msgflg); 982 } 983 984 COMPAT_SYSCALL_DEFINE4(msgsnd, int, msqid, compat_uptr_t, msgp, 985 compat_ssize_t, msgsz, int, msgflg) 986 { 987 return compat_ksys_msgsnd(msqid, msgp, msgsz, msgflg); 988 } 989 #endif 990 991 static inline int convert_mode(long *msgtyp, int msgflg) 992 { 993 if (msgflg & MSG_COPY) 994 return SEARCH_NUMBER; 995 /* 996 * find message of correct type. 997 * msgtyp = 0 => get first. 998 * msgtyp > 0 => get first message of matching type. 999 * msgtyp < 0 => get message with least type must be < abs(msgtype). 1000 */ 1001 if (*msgtyp == 0) 1002 return SEARCH_ANY; 1003 if (*msgtyp < 0) { 1004 if (*msgtyp == LONG_MIN) /* -LONG_MIN is undefined */ 1005 *msgtyp = LONG_MAX; 1006 else 1007 *msgtyp = -*msgtyp; 1008 return SEARCH_LESSEQUAL; 1009 } 1010 if (msgflg & MSG_EXCEPT) 1011 return SEARCH_NOTEQUAL; 1012 return SEARCH_EQUAL; 1013 } 1014 1015 static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz) 1016 { 1017 struct msgbuf __user *msgp = dest; 1018 size_t msgsz; 1019 1020 if (put_user(msg->m_type, &msgp->mtype)) 1021 return -EFAULT; 1022 1023 msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz; 1024 if (store_msg(msgp->mtext, msg, msgsz)) 1025 return -EFAULT; 1026 return msgsz; 1027 } 1028 1029 #ifdef CONFIG_CHECKPOINT_RESTORE 1030 /* 1031 * This function creates new kernel message structure, large enough to store 1032 * bufsz message bytes. 1033 */ 1034 static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz) 1035 { 1036 struct msg_msg *copy; 1037 1038 /* 1039 * Create dummy message to copy real message to. 1040 */ 1041 copy = load_msg(buf, bufsz); 1042 if (!IS_ERR(copy)) 1043 copy->m_ts = bufsz; 1044 return copy; 1045 } 1046 1047 static inline void free_copy(struct msg_msg *copy) 1048 { 1049 if (copy) 1050 free_msg(copy); 1051 } 1052 #else 1053 static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz) 1054 { 1055 return ERR_PTR(-ENOSYS); 1056 } 1057 1058 static inline void free_copy(struct msg_msg *copy) 1059 { 1060 } 1061 #endif 1062 1063 static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode) 1064 { 1065 struct msg_msg *msg, *found = NULL; 1066 long count = 0; 1067 1068 list_for_each_entry(msg, &msq->q_messages, m_list) { 1069 if (testmsg(msg, *msgtyp, mode) && 1070 !security_msg_queue_msgrcv(&msq->q_perm, msg, current, 1071 *msgtyp, mode)) { 1072 if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) { 1073 *msgtyp = msg->m_type - 1; 1074 found = msg; 1075 } else if (mode == SEARCH_NUMBER) { 1076 if (*msgtyp == count) 1077 return msg; 1078 } else 1079 return msg; 1080 count++; 1081 } 1082 } 1083 1084 return found ?: ERR_PTR(-EAGAIN); 1085 } 1086 1087 static long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg, 1088 long (*msg_handler)(void __user *, struct msg_msg *, size_t)) 1089 { 1090 int mode; 1091 struct msg_queue *msq; 1092 struct ipc_namespace *ns; 1093 struct msg_msg *msg, *copy = NULL; 1094 DEFINE_WAKE_Q(wake_q); 1095 1096 ns = current->nsproxy->ipc_ns; 1097 1098 if (msqid < 0 || (long) bufsz < 0) 1099 return -EINVAL; 1100 1101 if (msgflg & MSG_COPY) { 1102 if ((msgflg & MSG_EXCEPT) || !(msgflg & IPC_NOWAIT)) 1103 return -EINVAL; 1104 copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax)); 1105 if (IS_ERR(copy)) 1106 return PTR_ERR(copy); 1107 } 1108 mode = convert_mode(&msgtyp, msgflg); 1109 1110 rcu_read_lock(); 1111 msq = msq_obtain_object_check(ns, msqid); 1112 if (IS_ERR(msq)) { 1113 rcu_read_unlock(); 1114 free_copy(copy); 1115 return PTR_ERR(msq); 1116 } 1117 1118 for (;;) { 1119 struct msg_receiver msr_d; 1120 1121 msg = ERR_PTR(-EACCES); 1122 if (ipcperms(ns, &msq->q_perm, S_IRUGO)) 1123 goto out_unlock1; 1124 1125 ipc_lock_object(&msq->q_perm); 1126 1127 /* raced with RMID? */ 1128 if (!ipc_valid_object(&msq->q_perm)) { 1129 msg = ERR_PTR(-EIDRM); 1130 goto out_unlock0; 1131 } 1132 1133 msg = find_msg(msq, &msgtyp, mode); 1134 if (!IS_ERR(msg)) { 1135 /* 1136 * Found a suitable message. 1137 * Unlink it from the queue. 1138 */ 1139 if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) { 1140 msg = ERR_PTR(-E2BIG); 1141 goto out_unlock0; 1142 } 1143 /* 1144 * If we are copying, then do not unlink message and do 1145 * not update queue parameters. 1146 */ 1147 if (msgflg & MSG_COPY) { 1148 msg = copy_msg(msg, copy); 1149 goto out_unlock0; 1150 } 1151 1152 list_del(&msg->m_list); 1153 msq->q_qnum--; 1154 msq->q_rtime = ktime_get_real_seconds(); 1155 ipc_update_pid(&msq->q_lrpid, task_tgid(current)); 1156 msq->q_cbytes -= msg->m_ts; 1157 atomic_sub(msg->m_ts, &ns->msg_bytes); 1158 atomic_dec(&ns->msg_hdrs); 1159 ss_wakeup(msq, &wake_q, false); 1160 1161 goto out_unlock0; 1162 } 1163 1164 /* No message waiting. Wait for a message */ 1165 if (msgflg & IPC_NOWAIT) { 1166 msg = ERR_PTR(-ENOMSG); 1167 goto out_unlock0; 1168 } 1169 1170 list_add_tail(&msr_d.r_list, &msq->q_receivers); 1171 msr_d.r_tsk = current; 1172 msr_d.r_msgtype = msgtyp; 1173 msr_d.r_mode = mode; 1174 if (msgflg & MSG_NOERROR) 1175 msr_d.r_maxsize = INT_MAX; 1176 else 1177 msr_d.r_maxsize = bufsz; 1178 1179 /* memory barrier not require due to ipc_lock_object() */ 1180 WRITE_ONCE(msr_d.r_msg, ERR_PTR(-EAGAIN)); 1181 1182 /* memory barrier not required, we own ipc_lock_object() */ 1183 __set_current_state(TASK_INTERRUPTIBLE); 1184 1185 ipc_unlock_object(&msq->q_perm); 1186 rcu_read_unlock(); 1187 schedule(); 1188 1189 /* 1190 * Lockless receive, part 1: 1191 * We don't hold a reference to the queue and getting a 1192 * reference would defeat the idea of a lockless operation, 1193 * thus the code relies on rcu to guarantee the existence of 1194 * msq: 1195 * Prior to destruction, expunge_all(-EIRDM) changes r_msg. 1196 * Thus if r_msg is -EAGAIN, then the queue not yet destroyed. 1197 */ 1198 rcu_read_lock(); 1199 1200 /* 1201 * Lockless receive, part 2: 1202 * The work in pipelined_send() and expunge_all(): 1203 * - Set pointer to message 1204 * - Queue the receiver task for later wakeup 1205 * - Wake up the process after the lock is dropped. 1206 * 1207 * Should the process wake up before this wakeup (due to a 1208 * signal) it will either see the message and continue ... 1209 */ 1210 msg = READ_ONCE(msr_d.r_msg); 1211 if (msg != ERR_PTR(-EAGAIN)) { 1212 /* see MSG_BARRIER for purpose/pairing */ 1213 smp_acquire__after_ctrl_dep(); 1214 1215 goto out_unlock1; 1216 } 1217 1218 /* 1219 * ... or see -EAGAIN, acquire the lock to check the message 1220 * again. 1221 */ 1222 ipc_lock_object(&msq->q_perm); 1223 1224 msg = READ_ONCE(msr_d.r_msg); 1225 if (msg != ERR_PTR(-EAGAIN)) 1226 goto out_unlock0; 1227 1228 list_del(&msr_d.r_list); 1229 if (signal_pending(current)) { 1230 msg = ERR_PTR(-ERESTARTNOHAND); 1231 goto out_unlock0; 1232 } 1233 1234 ipc_unlock_object(&msq->q_perm); 1235 } 1236 1237 out_unlock0: 1238 ipc_unlock_object(&msq->q_perm); 1239 wake_up_q(&wake_q); 1240 out_unlock1: 1241 rcu_read_unlock(); 1242 if (IS_ERR(msg)) { 1243 free_copy(copy); 1244 return PTR_ERR(msg); 1245 } 1246 1247 bufsz = msg_handler(buf, msg, bufsz); 1248 free_msg(msg); 1249 1250 return bufsz; 1251 } 1252 1253 long ksys_msgrcv(int msqid, struct msgbuf __user *msgp, size_t msgsz, 1254 long msgtyp, int msgflg) 1255 { 1256 return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill); 1257 } 1258 1259 SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz, 1260 long, msgtyp, int, msgflg) 1261 { 1262 return ksys_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg); 1263 } 1264 1265 #ifdef CONFIG_COMPAT 1266 static long compat_do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz) 1267 { 1268 struct compat_msgbuf __user *msgp = dest; 1269 size_t msgsz; 1270 1271 if (put_user(msg->m_type, &msgp->mtype)) 1272 return -EFAULT; 1273 1274 msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz; 1275 if (store_msg(msgp->mtext, msg, msgsz)) 1276 return -EFAULT; 1277 return msgsz; 1278 } 1279 1280 long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz, 1281 compat_long_t msgtyp, int msgflg) 1282 { 1283 return do_msgrcv(msqid, compat_ptr(msgp), (ssize_t)msgsz, (long)msgtyp, 1284 msgflg, compat_do_msg_fill); 1285 } 1286 1287 COMPAT_SYSCALL_DEFINE5(msgrcv, int, msqid, compat_uptr_t, msgp, 1288 compat_ssize_t, msgsz, compat_long_t, msgtyp, 1289 int, msgflg) 1290 { 1291 return compat_ksys_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg); 1292 } 1293 #endif 1294 1295 void msg_init_ns(struct ipc_namespace *ns) 1296 { 1297 ns->msg_ctlmax = MSGMAX; 1298 ns->msg_ctlmnb = MSGMNB; 1299 ns->msg_ctlmni = MSGMNI; 1300 1301 atomic_set(&ns->msg_bytes, 0); 1302 atomic_set(&ns->msg_hdrs, 0); 1303 ipc_init_ids(&ns->ids[IPC_MSG_IDS]); 1304 } 1305 1306 #ifdef CONFIG_IPC_NS 1307 void msg_exit_ns(struct ipc_namespace *ns) 1308 { 1309 free_ipcs(ns, &msg_ids(ns), freeque); 1310 idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr); 1311 rhashtable_destroy(&ns->ids[IPC_MSG_IDS].key_ht); 1312 } 1313 #endif 1314 1315 #ifdef CONFIG_PROC_FS 1316 static int sysvipc_msg_proc_show(struct seq_file *s, void *it) 1317 { 1318 struct pid_namespace *pid_ns = ipc_seq_pid_ns(s); 1319 struct user_namespace *user_ns = seq_user_ns(s); 1320 struct kern_ipc_perm *ipcp = it; 1321 struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm); 1322 1323 seq_printf(s, 1324 "%10d %10d %4o %10lu %10lu %5u %5u %5u %5u %5u %5u %10llu %10llu %10llu\n", 1325 msq->q_perm.key, 1326 msq->q_perm.id, 1327 msq->q_perm.mode, 1328 msq->q_cbytes, 1329 msq->q_qnum, 1330 pid_nr_ns(msq->q_lspid, pid_ns), 1331 pid_nr_ns(msq->q_lrpid, pid_ns), 1332 from_kuid_munged(user_ns, msq->q_perm.uid), 1333 from_kgid_munged(user_ns, msq->q_perm.gid), 1334 from_kuid_munged(user_ns, msq->q_perm.cuid), 1335 from_kgid_munged(user_ns, msq->q_perm.cgid), 1336 msq->q_stime, 1337 msq->q_rtime, 1338 msq->q_ctime); 1339 1340 return 0; 1341 } 1342 #endif 1343 1344 void __init msg_init(void) 1345 { 1346 msg_init_ns(&init_ipc_ns); 1347 1348 ipc_init_proc_interface("sysvipc/msg", 1349 " key msqid perms cbytes qnum lspid lrpid uid gid cuid cgid stime rtime ctime\n", 1350 IPC_MSG_IDS, sysvipc_msg_proc_show); 1351 } 1352