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