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 kfree(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 = kmalloc(sizeof(*msq), GFP_KERNEL_ACCOUNT); 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 kfree(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 struct task_struct *r_tsk; 255 256 r_tsk = get_task_struct(msr->r_tsk); 257 258 /* see MSG_BARRIER for purpose/pairing */ 259 smp_store_release(&msr->r_msg, ERR_PTR(res)); 260 wake_q_add_safe(wake_q, r_tsk); 261 } 262 } 263 264 /* 265 * freeque() wakes up waiters on the sender and receiver waiting queue, 266 * removes the message queue from message queue ID IDR, and cleans up all the 267 * messages associated with this queue. 268 * 269 * msg_ids.rwsem (writer) and the spinlock for this message queue are held 270 * before freeque() is called. msg_ids.rwsem remains locked on exit. 271 */ 272 static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp) 273 __releases(RCU) 274 __releases(&msq->q_perm) 275 { 276 struct msg_msg *msg, *t; 277 struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm); 278 DEFINE_WAKE_Q(wake_q); 279 280 expunge_all(msq, -EIDRM, &wake_q); 281 ss_wakeup(msq, &wake_q, true); 282 msg_rmid(ns, msq); 283 ipc_unlock_object(&msq->q_perm); 284 wake_up_q(&wake_q); 285 rcu_read_unlock(); 286 287 list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) { 288 atomic_dec(&ns->msg_hdrs); 289 free_msg(msg); 290 } 291 atomic_sub(msq->q_cbytes, &ns->msg_bytes); 292 ipc_update_pid(&msq->q_lspid, NULL); 293 ipc_update_pid(&msq->q_lrpid, NULL); 294 ipc_rcu_putref(&msq->q_perm, msg_rcu_free); 295 } 296 297 long ksys_msgget(key_t key, int msgflg) 298 { 299 struct ipc_namespace *ns; 300 static const struct ipc_ops msg_ops = { 301 .getnew = newque, 302 .associate = security_msg_queue_associate, 303 }; 304 struct ipc_params msg_params; 305 306 ns = current->nsproxy->ipc_ns; 307 308 msg_params.key = key; 309 msg_params.flg = msgflg; 310 311 return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params); 312 } 313 314 SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg) 315 { 316 return ksys_msgget(key, msgflg); 317 } 318 319 static inline unsigned long 320 copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version) 321 { 322 switch (version) { 323 case IPC_64: 324 return copy_to_user(buf, in, sizeof(*in)); 325 case IPC_OLD: 326 { 327 struct msqid_ds out; 328 329 memset(&out, 0, sizeof(out)); 330 331 ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm); 332 333 out.msg_stime = in->msg_stime; 334 out.msg_rtime = in->msg_rtime; 335 out.msg_ctime = in->msg_ctime; 336 337 if (in->msg_cbytes > USHRT_MAX) 338 out.msg_cbytes = USHRT_MAX; 339 else 340 out.msg_cbytes = in->msg_cbytes; 341 out.msg_lcbytes = in->msg_cbytes; 342 343 if (in->msg_qnum > USHRT_MAX) 344 out.msg_qnum = USHRT_MAX; 345 else 346 out.msg_qnum = in->msg_qnum; 347 348 if (in->msg_qbytes > USHRT_MAX) 349 out.msg_qbytes = USHRT_MAX; 350 else 351 out.msg_qbytes = in->msg_qbytes; 352 out.msg_lqbytes = in->msg_qbytes; 353 354 out.msg_lspid = in->msg_lspid; 355 out.msg_lrpid = in->msg_lrpid; 356 357 return copy_to_user(buf, &out, sizeof(out)); 358 } 359 default: 360 return -EINVAL; 361 } 362 } 363 364 static inline unsigned long 365 copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version) 366 { 367 switch (version) { 368 case IPC_64: 369 if (copy_from_user(out, buf, sizeof(*out))) 370 return -EFAULT; 371 return 0; 372 case IPC_OLD: 373 { 374 struct msqid_ds tbuf_old; 375 376 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old))) 377 return -EFAULT; 378 379 out->msg_perm.uid = tbuf_old.msg_perm.uid; 380 out->msg_perm.gid = tbuf_old.msg_perm.gid; 381 out->msg_perm.mode = tbuf_old.msg_perm.mode; 382 383 if (tbuf_old.msg_qbytes == 0) 384 out->msg_qbytes = tbuf_old.msg_lqbytes; 385 else 386 out->msg_qbytes = tbuf_old.msg_qbytes; 387 388 return 0; 389 } 390 default: 391 return -EINVAL; 392 } 393 } 394 395 /* 396 * This function handles some msgctl commands which require the rwsem 397 * to be held in write mode. 398 * NOTE: no locks must be held, the rwsem is taken inside this function. 399 */ 400 static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd, 401 struct ipc64_perm *perm, int msg_qbytes) 402 { 403 struct kern_ipc_perm *ipcp; 404 struct msg_queue *msq; 405 int err; 406 407 down_write(&msg_ids(ns).rwsem); 408 rcu_read_lock(); 409 410 ipcp = ipcctl_obtain_check(ns, &msg_ids(ns), msqid, cmd, 411 perm, msg_qbytes); 412 if (IS_ERR(ipcp)) { 413 err = PTR_ERR(ipcp); 414 goto out_unlock1; 415 } 416 417 msq = container_of(ipcp, struct msg_queue, q_perm); 418 419 err = security_msg_queue_msgctl(&msq->q_perm, cmd); 420 if (err) 421 goto out_unlock1; 422 423 switch (cmd) { 424 case IPC_RMID: 425 ipc_lock_object(&msq->q_perm); 426 /* freeque unlocks the ipc object and rcu */ 427 freeque(ns, ipcp); 428 goto out_up; 429 case IPC_SET: 430 { 431 DEFINE_WAKE_Q(wake_q); 432 433 if (msg_qbytes > ns->msg_ctlmnb && 434 !capable(CAP_SYS_RESOURCE)) { 435 err = -EPERM; 436 goto out_unlock1; 437 } 438 439 ipc_lock_object(&msq->q_perm); 440 err = ipc_update_perm(perm, ipcp); 441 if (err) 442 goto out_unlock0; 443 444 msq->q_qbytes = msg_qbytes; 445 446 msq->q_ctime = ktime_get_real_seconds(); 447 /* 448 * Sleeping receivers might be excluded by 449 * stricter permissions. 450 */ 451 expunge_all(msq, -EAGAIN, &wake_q); 452 /* 453 * Sleeping senders might be able to send 454 * due to a larger queue size. 455 */ 456 ss_wakeup(msq, &wake_q, false); 457 ipc_unlock_object(&msq->q_perm); 458 wake_up_q(&wake_q); 459 460 goto out_unlock1; 461 } 462 default: 463 err = -EINVAL; 464 goto out_unlock1; 465 } 466 467 out_unlock0: 468 ipc_unlock_object(&msq->q_perm); 469 out_unlock1: 470 rcu_read_unlock(); 471 out_up: 472 up_write(&msg_ids(ns).rwsem); 473 return err; 474 } 475 476 static int msgctl_info(struct ipc_namespace *ns, int msqid, 477 int cmd, struct msginfo *msginfo) 478 { 479 int err; 480 int max_idx; 481 482 /* 483 * We must not return kernel stack data. 484 * due to padding, it's not enough 485 * to set all member fields. 486 */ 487 err = security_msg_queue_msgctl(NULL, cmd); 488 if (err) 489 return err; 490 491 memset(msginfo, 0, sizeof(*msginfo)); 492 msginfo->msgmni = ns->msg_ctlmni; 493 msginfo->msgmax = ns->msg_ctlmax; 494 msginfo->msgmnb = ns->msg_ctlmnb; 495 msginfo->msgssz = MSGSSZ; 496 msginfo->msgseg = MSGSEG; 497 down_read(&msg_ids(ns).rwsem); 498 if (cmd == MSG_INFO) { 499 msginfo->msgpool = msg_ids(ns).in_use; 500 msginfo->msgmap = atomic_read(&ns->msg_hdrs); 501 msginfo->msgtql = atomic_read(&ns->msg_bytes); 502 } else { 503 msginfo->msgmap = MSGMAP; 504 msginfo->msgpool = MSGPOOL; 505 msginfo->msgtql = MSGTQL; 506 } 507 max_idx = ipc_get_maxidx(&msg_ids(ns)); 508 up_read(&msg_ids(ns).rwsem); 509 return (max_idx < 0) ? 0 : max_idx; 510 } 511 512 static int msgctl_stat(struct ipc_namespace *ns, int msqid, 513 int cmd, struct msqid64_ds *p) 514 { 515 struct msg_queue *msq; 516 int err; 517 518 memset(p, 0, sizeof(*p)); 519 520 rcu_read_lock(); 521 if (cmd == MSG_STAT || cmd == MSG_STAT_ANY) { 522 msq = msq_obtain_object(ns, msqid); 523 if (IS_ERR(msq)) { 524 err = PTR_ERR(msq); 525 goto out_unlock; 526 } 527 } else { /* IPC_STAT */ 528 msq = msq_obtain_object_check(ns, msqid); 529 if (IS_ERR(msq)) { 530 err = PTR_ERR(msq); 531 goto out_unlock; 532 } 533 } 534 535 /* see comment for SHM_STAT_ANY */ 536 if (cmd == MSG_STAT_ANY) 537 audit_ipc_obj(&msq->q_perm); 538 else { 539 err = -EACCES; 540 if (ipcperms(ns, &msq->q_perm, S_IRUGO)) 541 goto out_unlock; 542 } 543 544 err = security_msg_queue_msgctl(&msq->q_perm, cmd); 545 if (err) 546 goto out_unlock; 547 548 ipc_lock_object(&msq->q_perm); 549 550 if (!ipc_valid_object(&msq->q_perm)) { 551 ipc_unlock_object(&msq->q_perm); 552 err = -EIDRM; 553 goto out_unlock; 554 } 555 556 kernel_to_ipc64_perm(&msq->q_perm, &p->msg_perm); 557 p->msg_stime = msq->q_stime; 558 p->msg_rtime = msq->q_rtime; 559 p->msg_ctime = msq->q_ctime; 560 #ifndef CONFIG_64BIT 561 p->msg_stime_high = msq->q_stime >> 32; 562 p->msg_rtime_high = msq->q_rtime >> 32; 563 p->msg_ctime_high = msq->q_ctime >> 32; 564 #endif 565 p->msg_cbytes = msq->q_cbytes; 566 p->msg_qnum = msq->q_qnum; 567 p->msg_qbytes = msq->q_qbytes; 568 p->msg_lspid = pid_vnr(msq->q_lspid); 569 p->msg_lrpid = pid_vnr(msq->q_lrpid); 570 571 if (cmd == IPC_STAT) { 572 /* 573 * As defined in SUS: 574 * Return 0 on success 575 */ 576 err = 0; 577 } else { 578 /* 579 * MSG_STAT and MSG_STAT_ANY (both Linux specific) 580 * Return the full id, including the sequence number 581 */ 582 err = msq->q_perm.id; 583 } 584 585 ipc_unlock_object(&msq->q_perm); 586 out_unlock: 587 rcu_read_unlock(); 588 return err; 589 } 590 591 static long ksys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf, int version) 592 { 593 struct ipc_namespace *ns; 594 struct msqid64_ds msqid64; 595 int err; 596 597 if (msqid < 0 || cmd < 0) 598 return -EINVAL; 599 600 ns = current->nsproxy->ipc_ns; 601 602 switch (cmd) { 603 case IPC_INFO: 604 case MSG_INFO: { 605 struct msginfo msginfo; 606 err = msgctl_info(ns, msqid, cmd, &msginfo); 607 if (err < 0) 608 return err; 609 if (copy_to_user(buf, &msginfo, sizeof(struct msginfo))) 610 err = -EFAULT; 611 return err; 612 } 613 case MSG_STAT: /* msqid is an index rather than a msg queue id */ 614 case MSG_STAT_ANY: 615 case IPC_STAT: 616 err = msgctl_stat(ns, msqid, cmd, &msqid64); 617 if (err < 0) 618 return err; 619 if (copy_msqid_to_user(buf, &msqid64, version)) 620 err = -EFAULT; 621 return err; 622 case IPC_SET: 623 if (copy_msqid_from_user(&msqid64, buf, version)) 624 return -EFAULT; 625 return msgctl_down(ns, msqid, cmd, &msqid64.msg_perm, 626 msqid64.msg_qbytes); 627 case IPC_RMID: 628 return msgctl_down(ns, msqid, cmd, NULL, 0); 629 default: 630 return -EINVAL; 631 } 632 } 633 634 SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf) 635 { 636 return ksys_msgctl(msqid, cmd, buf, IPC_64); 637 } 638 639 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION 640 long ksys_old_msgctl(int msqid, int cmd, struct msqid_ds __user *buf) 641 { 642 int version = ipc_parse_version(&cmd); 643 644 return ksys_msgctl(msqid, cmd, buf, version); 645 } 646 647 SYSCALL_DEFINE3(old_msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf) 648 { 649 return ksys_old_msgctl(msqid, cmd, buf); 650 } 651 #endif 652 653 #ifdef CONFIG_COMPAT 654 655 struct compat_msqid_ds { 656 struct compat_ipc_perm msg_perm; 657 compat_uptr_t msg_first; 658 compat_uptr_t msg_last; 659 old_time32_t msg_stime; 660 old_time32_t msg_rtime; 661 old_time32_t msg_ctime; 662 compat_ulong_t msg_lcbytes; 663 compat_ulong_t msg_lqbytes; 664 unsigned short msg_cbytes; 665 unsigned short msg_qnum; 666 unsigned short msg_qbytes; 667 compat_ipc_pid_t msg_lspid; 668 compat_ipc_pid_t msg_lrpid; 669 }; 670 671 static int copy_compat_msqid_from_user(struct msqid64_ds *out, void __user *buf, 672 int version) 673 { 674 memset(out, 0, sizeof(*out)); 675 if (version == IPC_64) { 676 struct compat_msqid64_ds __user *p = buf; 677 if (get_compat_ipc64_perm(&out->msg_perm, &p->msg_perm)) 678 return -EFAULT; 679 if (get_user(out->msg_qbytes, &p->msg_qbytes)) 680 return -EFAULT; 681 } else { 682 struct compat_msqid_ds __user *p = buf; 683 if (get_compat_ipc_perm(&out->msg_perm, &p->msg_perm)) 684 return -EFAULT; 685 if (get_user(out->msg_qbytes, &p->msg_qbytes)) 686 return -EFAULT; 687 } 688 return 0; 689 } 690 691 static int copy_compat_msqid_to_user(void __user *buf, struct msqid64_ds *in, 692 int version) 693 { 694 if (version == IPC_64) { 695 struct compat_msqid64_ds v; 696 memset(&v, 0, sizeof(v)); 697 to_compat_ipc64_perm(&v.msg_perm, &in->msg_perm); 698 v.msg_stime = lower_32_bits(in->msg_stime); 699 v.msg_stime_high = upper_32_bits(in->msg_stime); 700 v.msg_rtime = lower_32_bits(in->msg_rtime); 701 v.msg_rtime_high = upper_32_bits(in->msg_rtime); 702 v.msg_ctime = lower_32_bits(in->msg_ctime); 703 v.msg_ctime_high = upper_32_bits(in->msg_ctime); 704 v.msg_cbytes = in->msg_cbytes; 705 v.msg_qnum = in->msg_qnum; 706 v.msg_qbytes = in->msg_qbytes; 707 v.msg_lspid = in->msg_lspid; 708 v.msg_lrpid = in->msg_lrpid; 709 return copy_to_user(buf, &v, sizeof(v)); 710 } else { 711 struct compat_msqid_ds v; 712 memset(&v, 0, sizeof(v)); 713 to_compat_ipc_perm(&v.msg_perm, &in->msg_perm); 714 v.msg_stime = in->msg_stime; 715 v.msg_rtime = in->msg_rtime; 716 v.msg_ctime = in->msg_ctime; 717 v.msg_cbytes = in->msg_cbytes; 718 v.msg_qnum = in->msg_qnum; 719 v.msg_qbytes = in->msg_qbytes; 720 v.msg_lspid = in->msg_lspid; 721 v.msg_lrpid = in->msg_lrpid; 722 return copy_to_user(buf, &v, sizeof(v)); 723 } 724 } 725 726 static long compat_ksys_msgctl(int msqid, int cmd, void __user *uptr, int version) 727 { 728 struct ipc_namespace *ns; 729 int err; 730 struct msqid64_ds msqid64; 731 732 ns = current->nsproxy->ipc_ns; 733 734 if (msqid < 0 || cmd < 0) 735 return -EINVAL; 736 737 switch (cmd & (~IPC_64)) { 738 case IPC_INFO: 739 case MSG_INFO: { 740 struct msginfo msginfo; 741 err = msgctl_info(ns, msqid, cmd, &msginfo); 742 if (err < 0) 743 return err; 744 if (copy_to_user(uptr, &msginfo, sizeof(struct msginfo))) 745 err = -EFAULT; 746 return err; 747 } 748 case IPC_STAT: 749 case MSG_STAT: 750 case MSG_STAT_ANY: 751 err = msgctl_stat(ns, msqid, cmd, &msqid64); 752 if (err < 0) 753 return err; 754 if (copy_compat_msqid_to_user(uptr, &msqid64, version)) 755 err = -EFAULT; 756 return err; 757 case IPC_SET: 758 if (copy_compat_msqid_from_user(&msqid64, uptr, version)) 759 return -EFAULT; 760 return msgctl_down(ns, msqid, cmd, &msqid64.msg_perm, msqid64.msg_qbytes); 761 case IPC_RMID: 762 return msgctl_down(ns, msqid, cmd, NULL, 0); 763 default: 764 return -EINVAL; 765 } 766 } 767 768 COMPAT_SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, void __user *, uptr) 769 { 770 return compat_ksys_msgctl(msqid, cmd, uptr, IPC_64); 771 } 772 773 #ifdef CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION 774 long compat_ksys_old_msgctl(int msqid, int cmd, void __user *uptr) 775 { 776 int version = compat_ipc_parse_version(&cmd); 777 778 return compat_ksys_msgctl(msqid, cmd, uptr, version); 779 } 780 781 COMPAT_SYSCALL_DEFINE3(old_msgctl, int, msqid, int, cmd, void __user *, uptr) 782 { 783 return compat_ksys_old_msgctl(msqid, cmd, uptr); 784 } 785 #endif 786 #endif 787 788 static int testmsg(struct msg_msg *msg, long type, int mode) 789 { 790 switch (mode) { 791 case SEARCH_ANY: 792 case SEARCH_NUMBER: 793 return 1; 794 case SEARCH_LESSEQUAL: 795 if (msg->m_type <= type) 796 return 1; 797 break; 798 case SEARCH_EQUAL: 799 if (msg->m_type == type) 800 return 1; 801 break; 802 case SEARCH_NOTEQUAL: 803 if (msg->m_type != type) 804 return 1; 805 break; 806 } 807 return 0; 808 } 809 810 static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg, 811 struct wake_q_head *wake_q) 812 { 813 struct msg_receiver *msr, *t; 814 815 list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) { 816 if (testmsg(msg, msr->r_msgtype, msr->r_mode) && 817 !security_msg_queue_msgrcv(&msq->q_perm, msg, msr->r_tsk, 818 msr->r_msgtype, msr->r_mode)) { 819 820 list_del(&msr->r_list); 821 if (msr->r_maxsize < msg->m_ts) { 822 wake_q_add(wake_q, msr->r_tsk); 823 824 /* See expunge_all regarding memory barrier */ 825 smp_store_release(&msr->r_msg, ERR_PTR(-E2BIG)); 826 } else { 827 ipc_update_pid(&msq->q_lrpid, task_pid(msr->r_tsk)); 828 msq->q_rtime = ktime_get_real_seconds(); 829 830 wake_q_add(wake_q, msr->r_tsk); 831 832 /* See expunge_all regarding memory barrier */ 833 smp_store_release(&msr->r_msg, msg); 834 return 1; 835 } 836 } 837 } 838 839 return 0; 840 } 841 842 static long do_msgsnd(int msqid, long mtype, void __user *mtext, 843 size_t msgsz, int msgflg) 844 { 845 struct msg_queue *msq; 846 struct msg_msg *msg; 847 int err; 848 struct ipc_namespace *ns; 849 DEFINE_WAKE_Q(wake_q); 850 851 ns = current->nsproxy->ipc_ns; 852 853 if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0) 854 return -EINVAL; 855 if (mtype < 1) 856 return -EINVAL; 857 858 msg = load_msg(mtext, msgsz); 859 if (IS_ERR(msg)) 860 return PTR_ERR(msg); 861 862 msg->m_type = mtype; 863 msg->m_ts = msgsz; 864 865 rcu_read_lock(); 866 msq = msq_obtain_object_check(ns, msqid); 867 if (IS_ERR(msq)) { 868 err = PTR_ERR(msq); 869 goto out_unlock1; 870 } 871 872 ipc_lock_object(&msq->q_perm); 873 874 for (;;) { 875 struct msg_sender s; 876 877 err = -EACCES; 878 if (ipcperms(ns, &msq->q_perm, S_IWUGO)) 879 goto out_unlock0; 880 881 /* raced with RMID? */ 882 if (!ipc_valid_object(&msq->q_perm)) { 883 err = -EIDRM; 884 goto out_unlock0; 885 } 886 887 err = security_msg_queue_msgsnd(&msq->q_perm, msg, msgflg); 888 if (err) 889 goto out_unlock0; 890 891 if (msg_fits_inqueue(msq, msgsz)) 892 break; 893 894 /* queue full, wait: */ 895 if (msgflg & IPC_NOWAIT) { 896 err = -EAGAIN; 897 goto out_unlock0; 898 } 899 900 /* enqueue the sender and prepare to block */ 901 ss_add(msq, &s, msgsz); 902 903 if (!ipc_rcu_getref(&msq->q_perm)) { 904 err = -EIDRM; 905 goto out_unlock0; 906 } 907 908 ipc_unlock_object(&msq->q_perm); 909 rcu_read_unlock(); 910 schedule(); 911 912 rcu_read_lock(); 913 ipc_lock_object(&msq->q_perm); 914 915 ipc_rcu_putref(&msq->q_perm, msg_rcu_free); 916 /* raced with RMID? */ 917 if (!ipc_valid_object(&msq->q_perm)) { 918 err = -EIDRM; 919 goto out_unlock0; 920 } 921 ss_del(&s); 922 923 if (signal_pending(current)) { 924 err = -ERESTARTNOHAND; 925 goto out_unlock0; 926 } 927 928 } 929 930 ipc_update_pid(&msq->q_lspid, task_tgid(current)); 931 msq->q_stime = ktime_get_real_seconds(); 932 933 if (!pipelined_send(msq, msg, &wake_q)) { 934 /* no one is waiting for this message, enqueue it */ 935 list_add_tail(&msg->m_list, &msq->q_messages); 936 msq->q_cbytes += msgsz; 937 msq->q_qnum++; 938 atomic_add(msgsz, &ns->msg_bytes); 939 atomic_inc(&ns->msg_hdrs); 940 } 941 942 err = 0; 943 msg = NULL; 944 945 out_unlock0: 946 ipc_unlock_object(&msq->q_perm); 947 wake_up_q(&wake_q); 948 out_unlock1: 949 rcu_read_unlock(); 950 if (msg != NULL) 951 free_msg(msg); 952 return err; 953 } 954 955 long ksys_msgsnd(int msqid, struct msgbuf __user *msgp, size_t msgsz, 956 int msgflg) 957 { 958 long mtype; 959 960 if (get_user(mtype, &msgp->mtype)) 961 return -EFAULT; 962 return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg); 963 } 964 965 SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz, 966 int, msgflg) 967 { 968 return ksys_msgsnd(msqid, msgp, msgsz, msgflg); 969 } 970 971 #ifdef CONFIG_COMPAT 972 973 struct compat_msgbuf { 974 compat_long_t mtype; 975 char mtext[1]; 976 }; 977 978 long compat_ksys_msgsnd(int msqid, compat_uptr_t msgp, 979 compat_ssize_t msgsz, int msgflg) 980 { 981 struct compat_msgbuf __user *up = compat_ptr(msgp); 982 compat_long_t mtype; 983 984 if (get_user(mtype, &up->mtype)) 985 return -EFAULT; 986 return do_msgsnd(msqid, mtype, up->mtext, (ssize_t)msgsz, msgflg); 987 } 988 989 COMPAT_SYSCALL_DEFINE4(msgsnd, int, msqid, compat_uptr_t, msgp, 990 compat_ssize_t, msgsz, int, msgflg) 991 { 992 return compat_ksys_msgsnd(msqid, msgp, msgsz, msgflg); 993 } 994 #endif 995 996 static inline int convert_mode(long *msgtyp, int msgflg) 997 { 998 if (msgflg & MSG_COPY) 999 return SEARCH_NUMBER; 1000 /* 1001 * find message of correct type. 1002 * msgtyp = 0 => get first. 1003 * msgtyp > 0 => get first message of matching type. 1004 * msgtyp < 0 => get message with least type must be < abs(msgtype). 1005 */ 1006 if (*msgtyp == 0) 1007 return SEARCH_ANY; 1008 if (*msgtyp < 0) { 1009 if (*msgtyp == LONG_MIN) /* -LONG_MIN is undefined */ 1010 *msgtyp = LONG_MAX; 1011 else 1012 *msgtyp = -*msgtyp; 1013 return SEARCH_LESSEQUAL; 1014 } 1015 if (msgflg & MSG_EXCEPT) 1016 return SEARCH_NOTEQUAL; 1017 return SEARCH_EQUAL; 1018 } 1019 1020 static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz) 1021 { 1022 struct msgbuf __user *msgp = dest; 1023 size_t msgsz; 1024 1025 if (put_user(msg->m_type, &msgp->mtype)) 1026 return -EFAULT; 1027 1028 msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz; 1029 if (store_msg(msgp->mtext, msg, msgsz)) 1030 return -EFAULT; 1031 return msgsz; 1032 } 1033 1034 #ifdef CONFIG_CHECKPOINT_RESTORE 1035 /* 1036 * This function creates new kernel message structure, large enough to store 1037 * bufsz message bytes. 1038 */ 1039 static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz) 1040 { 1041 struct msg_msg *copy; 1042 1043 /* 1044 * Create dummy message to copy real message to. 1045 */ 1046 copy = load_msg(buf, bufsz); 1047 if (!IS_ERR(copy)) 1048 copy->m_ts = bufsz; 1049 return copy; 1050 } 1051 1052 static inline void free_copy(struct msg_msg *copy) 1053 { 1054 if (copy) 1055 free_msg(copy); 1056 } 1057 #else 1058 static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz) 1059 { 1060 return ERR_PTR(-ENOSYS); 1061 } 1062 1063 static inline void free_copy(struct msg_msg *copy) 1064 { 1065 } 1066 #endif 1067 1068 static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode) 1069 { 1070 struct msg_msg *msg, *found = NULL; 1071 long count = 0; 1072 1073 list_for_each_entry(msg, &msq->q_messages, m_list) { 1074 if (testmsg(msg, *msgtyp, mode) && 1075 !security_msg_queue_msgrcv(&msq->q_perm, msg, current, 1076 *msgtyp, mode)) { 1077 if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) { 1078 *msgtyp = msg->m_type - 1; 1079 found = msg; 1080 } else if (mode == SEARCH_NUMBER) { 1081 if (*msgtyp == count) 1082 return msg; 1083 } else 1084 return msg; 1085 count++; 1086 } 1087 } 1088 1089 return found ?: ERR_PTR(-EAGAIN); 1090 } 1091 1092 static long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg, 1093 long (*msg_handler)(void __user *, struct msg_msg *, size_t)) 1094 { 1095 int mode; 1096 struct msg_queue *msq; 1097 struct ipc_namespace *ns; 1098 struct msg_msg *msg, *copy = NULL; 1099 DEFINE_WAKE_Q(wake_q); 1100 1101 ns = current->nsproxy->ipc_ns; 1102 1103 if (msqid < 0 || (long) bufsz < 0) 1104 return -EINVAL; 1105 1106 if (msgflg & MSG_COPY) { 1107 if ((msgflg & MSG_EXCEPT) || !(msgflg & IPC_NOWAIT)) 1108 return -EINVAL; 1109 copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax)); 1110 if (IS_ERR(copy)) 1111 return PTR_ERR(copy); 1112 } 1113 mode = convert_mode(&msgtyp, msgflg); 1114 1115 rcu_read_lock(); 1116 msq = msq_obtain_object_check(ns, msqid); 1117 if (IS_ERR(msq)) { 1118 rcu_read_unlock(); 1119 free_copy(copy); 1120 return PTR_ERR(msq); 1121 } 1122 1123 for (;;) { 1124 struct msg_receiver msr_d; 1125 1126 msg = ERR_PTR(-EACCES); 1127 if (ipcperms(ns, &msq->q_perm, S_IRUGO)) 1128 goto out_unlock1; 1129 1130 ipc_lock_object(&msq->q_perm); 1131 1132 /* raced with RMID? */ 1133 if (!ipc_valid_object(&msq->q_perm)) { 1134 msg = ERR_PTR(-EIDRM); 1135 goto out_unlock0; 1136 } 1137 1138 msg = find_msg(msq, &msgtyp, mode); 1139 if (!IS_ERR(msg)) { 1140 /* 1141 * Found a suitable message. 1142 * Unlink it from the queue. 1143 */ 1144 if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) { 1145 msg = ERR_PTR(-E2BIG); 1146 goto out_unlock0; 1147 } 1148 /* 1149 * If we are copying, then do not unlink message and do 1150 * not update queue parameters. 1151 */ 1152 if (msgflg & MSG_COPY) { 1153 msg = copy_msg(msg, copy); 1154 goto out_unlock0; 1155 } 1156 1157 list_del(&msg->m_list); 1158 msq->q_qnum--; 1159 msq->q_rtime = ktime_get_real_seconds(); 1160 ipc_update_pid(&msq->q_lrpid, task_tgid(current)); 1161 msq->q_cbytes -= msg->m_ts; 1162 atomic_sub(msg->m_ts, &ns->msg_bytes); 1163 atomic_dec(&ns->msg_hdrs); 1164 ss_wakeup(msq, &wake_q, false); 1165 1166 goto out_unlock0; 1167 } 1168 1169 /* No message waiting. Wait for a message */ 1170 if (msgflg & IPC_NOWAIT) { 1171 msg = ERR_PTR(-ENOMSG); 1172 goto out_unlock0; 1173 } 1174 1175 list_add_tail(&msr_d.r_list, &msq->q_receivers); 1176 msr_d.r_tsk = current; 1177 msr_d.r_msgtype = msgtyp; 1178 msr_d.r_mode = mode; 1179 if (msgflg & MSG_NOERROR) 1180 msr_d.r_maxsize = INT_MAX; 1181 else 1182 msr_d.r_maxsize = bufsz; 1183 1184 /* memory barrier not require due to ipc_lock_object() */ 1185 WRITE_ONCE(msr_d.r_msg, ERR_PTR(-EAGAIN)); 1186 1187 /* memory barrier not required, we own ipc_lock_object() */ 1188 __set_current_state(TASK_INTERRUPTIBLE); 1189 1190 ipc_unlock_object(&msq->q_perm); 1191 rcu_read_unlock(); 1192 schedule(); 1193 1194 /* 1195 * Lockless receive, part 1: 1196 * We don't hold a reference to the queue and getting a 1197 * reference would defeat the idea of a lockless operation, 1198 * thus the code relies on rcu to guarantee the existence of 1199 * msq: 1200 * Prior to destruction, expunge_all(-EIRDM) changes r_msg. 1201 * Thus if r_msg is -EAGAIN, then the queue not yet destroyed. 1202 */ 1203 rcu_read_lock(); 1204 1205 /* 1206 * Lockless receive, part 2: 1207 * The work in pipelined_send() and expunge_all(): 1208 * - Set pointer to message 1209 * - Queue the receiver task for later wakeup 1210 * - Wake up the process after the lock is dropped. 1211 * 1212 * Should the process wake up before this wakeup (due to a 1213 * signal) it will either see the message and continue ... 1214 */ 1215 msg = READ_ONCE(msr_d.r_msg); 1216 if (msg != ERR_PTR(-EAGAIN)) { 1217 /* see MSG_BARRIER for purpose/pairing */ 1218 smp_acquire__after_ctrl_dep(); 1219 1220 goto out_unlock1; 1221 } 1222 1223 /* 1224 * ... or see -EAGAIN, acquire the lock to check the message 1225 * again. 1226 */ 1227 ipc_lock_object(&msq->q_perm); 1228 1229 msg = READ_ONCE(msr_d.r_msg); 1230 if (msg != ERR_PTR(-EAGAIN)) 1231 goto out_unlock0; 1232 1233 list_del(&msr_d.r_list); 1234 if (signal_pending(current)) { 1235 msg = ERR_PTR(-ERESTARTNOHAND); 1236 goto out_unlock0; 1237 } 1238 1239 ipc_unlock_object(&msq->q_perm); 1240 } 1241 1242 out_unlock0: 1243 ipc_unlock_object(&msq->q_perm); 1244 wake_up_q(&wake_q); 1245 out_unlock1: 1246 rcu_read_unlock(); 1247 if (IS_ERR(msg)) { 1248 free_copy(copy); 1249 return PTR_ERR(msg); 1250 } 1251 1252 bufsz = msg_handler(buf, msg, bufsz); 1253 free_msg(msg); 1254 1255 return bufsz; 1256 } 1257 1258 long ksys_msgrcv(int msqid, struct msgbuf __user *msgp, size_t msgsz, 1259 long msgtyp, int msgflg) 1260 { 1261 return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill); 1262 } 1263 1264 SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz, 1265 long, msgtyp, int, msgflg) 1266 { 1267 return ksys_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg); 1268 } 1269 1270 #ifdef CONFIG_COMPAT 1271 static long compat_do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz) 1272 { 1273 struct compat_msgbuf __user *msgp = dest; 1274 size_t msgsz; 1275 1276 if (put_user(msg->m_type, &msgp->mtype)) 1277 return -EFAULT; 1278 1279 msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz; 1280 if (store_msg(msgp->mtext, msg, msgsz)) 1281 return -EFAULT; 1282 return msgsz; 1283 } 1284 1285 long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz, 1286 compat_long_t msgtyp, int msgflg) 1287 { 1288 return do_msgrcv(msqid, compat_ptr(msgp), (ssize_t)msgsz, (long)msgtyp, 1289 msgflg, compat_do_msg_fill); 1290 } 1291 1292 COMPAT_SYSCALL_DEFINE5(msgrcv, int, msqid, compat_uptr_t, msgp, 1293 compat_ssize_t, msgsz, compat_long_t, msgtyp, 1294 int, msgflg) 1295 { 1296 return compat_ksys_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg); 1297 } 1298 #endif 1299 1300 void msg_init_ns(struct ipc_namespace *ns) 1301 { 1302 ns->msg_ctlmax = MSGMAX; 1303 ns->msg_ctlmnb = MSGMNB; 1304 ns->msg_ctlmni = MSGMNI; 1305 1306 atomic_set(&ns->msg_bytes, 0); 1307 atomic_set(&ns->msg_hdrs, 0); 1308 ipc_init_ids(&ns->ids[IPC_MSG_IDS]); 1309 } 1310 1311 #ifdef CONFIG_IPC_NS 1312 void msg_exit_ns(struct ipc_namespace *ns) 1313 { 1314 free_ipcs(ns, &msg_ids(ns), freeque); 1315 idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr); 1316 rhashtable_destroy(&ns->ids[IPC_MSG_IDS].key_ht); 1317 } 1318 #endif 1319 1320 #ifdef CONFIG_PROC_FS 1321 static int sysvipc_msg_proc_show(struct seq_file *s, void *it) 1322 { 1323 struct pid_namespace *pid_ns = ipc_seq_pid_ns(s); 1324 struct user_namespace *user_ns = seq_user_ns(s); 1325 struct kern_ipc_perm *ipcp = it; 1326 struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm); 1327 1328 seq_printf(s, 1329 "%10d %10d %4o %10lu %10lu %5u %5u %5u %5u %5u %5u %10llu %10llu %10llu\n", 1330 msq->q_perm.key, 1331 msq->q_perm.id, 1332 msq->q_perm.mode, 1333 msq->q_cbytes, 1334 msq->q_qnum, 1335 pid_nr_ns(msq->q_lspid, pid_ns), 1336 pid_nr_ns(msq->q_lrpid, pid_ns), 1337 from_kuid_munged(user_ns, msq->q_perm.uid), 1338 from_kgid_munged(user_ns, msq->q_perm.gid), 1339 from_kuid_munged(user_ns, msq->q_perm.cuid), 1340 from_kgid_munged(user_ns, msq->q_perm.cgid), 1341 msq->q_stime, 1342 msq->q_rtime, 1343 msq->q_ctime); 1344 1345 return 0; 1346 } 1347 #endif 1348 1349 void __init msg_init(void) 1350 { 1351 msg_init_ns(&init_ipc_ns); 1352 1353 ipc_init_proc_interface("sysvipc/msg", 1354 " key msqid perms cbytes qnum lspid lrpid uid gid cuid cgid stime rtime ctime\n", 1355 IPC_MSG_IDS, sysvipc_msg_proc_show); 1356 } 1357