Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/sysv_msg.c
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1 /*- 2 * Implementation of SVID messages 3 * 4 * Author: Daniel Boulet 5 * 6 * Copyright 1993 Daniel Boulet and RTMX Inc. 7 * 8 * This system call was implemented by Daniel Boulet under contract from RTMX. 9 * 10 * Redistribution and use in source forms, with and without modification, 11 * are permitted provided that this entire comment appears intact. 12 * 13 * Redistribution in binary form may occur without any restrictions. 14 * Obviously, it would be nice if you gave credit where credit is due 15 * but requiring it would be too onerous. 16 * 17 * This software is provided ``AS IS'' without any warranties of any kind. 18 */ 19 /*- 20 * Copyright (c) 2003-2005 McAfee, Inc. 21 * All rights reserved. 22 * 23 * This software was developed for the FreeBSD Project in part by McAfee 24 * Research, the Security Research Division of McAfee, Inc under DARPA/SPAWAR 25 * contract N66001-01-C-8035 ("CBOSS"), as part of the DARPA CHATS research 26 * program. 27 * 28 * Redistribution and use in source and binary forms, with or without 29 * modification, are permitted provided that the following conditions 30 * are met: 31 * 1. Redistributions of source code must retain the above copyright 32 * notice, this list of conditions and the following disclaimer. 33 * 2. Redistributions in binary form must reproduce the above copyright 34 * notice, this list of conditions and the following disclaimer in the 35 * documentation and/or other materials provided with the distribution. 36 * 37 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 38 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 39 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 40 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 41 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 42 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 43 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 44 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 45 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 46 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 47 * SUCH DAMAGE. 48 */ 49 50 #include <sys/cdefs.h> 51 __FBSDID("$FreeBSD: releng/6.4/sys/kern/sysv_msg.c 174372 2007-12-06 22:00:05Z jhb $"); 52 53 #include "opt_sysvipc.h" 54 #include "opt_mac.h" 55 56 #include <sys/param.h> 57 #include <sys/systm.h> 58 #include <sys/sysproto.h> 59 #include <sys/kernel.h> 60 #include <sys/proc.h> 61 #include <sys/lock.h> 62 #include <sys/mac.h> 63 #include <sys/mutex.h> 64 #include <sys/module.h> 65 #include <sys/msg.h> 66 #include <sys/syscall.h> 67 #include <sys/syscallsubr.h> 68 #include <sys/sysent.h> 69 #include <sys/sysctl.h> 70 #include <sys/malloc.h> 71 #include <sys/jail.h> 72 73 static MALLOC_DEFINE(M_MSG, "msg", "SVID compatible message queues"); 74 75 static void msginit(void); 76 static int msgunload(void); 77 static int sysvmsg_modload(struct module *, int, void *); 78 79 #ifdef MSG_DEBUG 80 #define DPRINTF(a) printf a 81 #else 82 #define DPRINTF(a) 83 #endif 84 #ifdef MAC_DEBUG 85 #define MPRINTF(a) printf a 86 #else 87 #define MPRINTF(a) 88 #endif 89 90 static void msg_freehdr(struct msg *msghdr); 91 92 /* XXX casting to (sy_call_t *) is bogus, as usual. */ 93 static sy_call_t *msgcalls[] = { 94 (sy_call_t *)msgctl, (sy_call_t *)msgget, 95 (sy_call_t *)msgsnd, (sy_call_t *)msgrcv 96 }; 97 98 #ifndef MSGSSZ 99 #define MSGSSZ 8 /* Each segment must be 2^N long */ 100 #endif 101 #ifndef MSGSEG 102 #define MSGSEG 2048 /* must be less than 32767 */ 103 #endif 104 #define MSGMAX (MSGSSZ*MSGSEG) 105 #ifndef MSGMNB 106 #define MSGMNB 2048 /* max # of bytes in a queue */ 107 #endif 108 #ifndef MSGMNI 109 #define MSGMNI 40 110 #endif 111 #ifndef MSGTQL 112 #define MSGTQL 40 113 #endif 114 115 /* 116 * Based on the configuration parameters described in an SVR2 (yes, two) 117 * config(1m) man page. 118 * 119 * Each message is broken up and stored in segments that are msgssz bytes 120 * long. For efficiency reasons, this should be a power of two. Also, 121 * it doesn't make sense if it is less than 8 or greater than about 256. 122 * Consequently, msginit in kern/sysv_msg.c checks that msgssz is a power of 123 * two between 8 and 1024 inclusive (and panic's if it isn't). 124 */ 125 struct msginfo msginfo = { 126 MSGMAX, /* max chars in a message */ 127 MSGMNI, /* # of message queue identifiers */ 128 MSGMNB, /* max chars in a queue */ 129 MSGTQL, /* max messages in system */ 130 MSGSSZ, /* size of a message segment */ 131 /* (must be small power of 2 greater than 4) */ 132 MSGSEG /* number of message segments */ 133 }; 134 135 /* 136 * macros to convert between msqid_ds's and msqid's. 137 * (specific to this implementation) 138 */ 139 #define MSQID(ix,ds) ((ix) & 0xffff | (((ds).msg_perm.seq << 16) & 0xffff0000)) 140 #define MSQID_IX(id) ((id) & 0xffff) 141 #define MSQID_SEQ(id) (((id) >> 16) & 0xffff) 142 143 /* 144 * The rest of this file is specific to this particular implementation. 145 */ 146 147 struct msgmap { 148 short next; /* next segment in buffer */ 149 /* -1 -> available */ 150 /* 0..(MSGSEG-1) -> index of next segment */ 151 }; 152 153 #define MSG_LOCKED 01000 /* Is this msqid_ds locked? */ 154 155 static int nfree_msgmaps; /* # of free map entries */ 156 static short free_msgmaps; /* head of linked list of free map entries */ 157 static struct msg *free_msghdrs;/* list of free msg headers */ 158 static char *msgpool; /* MSGMAX byte long msg buffer pool */ 159 static struct msgmap *msgmaps; /* MSGSEG msgmap structures */ 160 static struct msg *msghdrs; /* MSGTQL msg headers */ 161 static struct msqid_kernel *msqids; /* MSGMNI msqid_kernel struct's */ 162 static struct mtx msq_mtx; /* global mutex for message queues. */ 163 164 static void 165 msginit() 166 { 167 register int i; 168 169 TUNABLE_INT_FETCH("kern.ipc.msgseg", &msginfo.msgseg); 170 TUNABLE_INT_FETCH("kern.ipc.msgssz", &msginfo.msgssz); 171 msginfo.msgmax = msginfo.msgseg * msginfo.msgssz; 172 TUNABLE_INT_FETCH("kern.ipc.msgmni", &msginfo.msgmni); 173 TUNABLE_INT_FETCH("kern.ipc.msgmnb", &msginfo.msgmnb); 174 TUNABLE_INT_FETCH("kern.ipc.msgtql", &msginfo.msgtql); 175 176 msgpool = malloc(msginfo.msgmax, M_MSG, M_WAITOK); 177 if (msgpool == NULL) 178 panic("msgpool is NULL"); 179 msgmaps = malloc(sizeof(struct msgmap) * msginfo.msgseg, M_MSG, M_WAITOK); 180 if (msgmaps == NULL) 181 panic("msgmaps is NULL"); 182 msghdrs = malloc(sizeof(struct msg) * msginfo.msgtql, M_MSG, M_WAITOK); 183 if (msghdrs == NULL) 184 panic("msghdrs is NULL"); 185 msqids = malloc(sizeof(struct msqid_kernel) * msginfo.msgmni, M_MSG, 186 M_WAITOK); 187 if (msqids == NULL) 188 panic("msqids is NULL"); 189 190 /* 191 * msginfo.msgssz should be a power of two for efficiency reasons. 192 * It is also pretty silly if msginfo.msgssz is less than 8 193 * or greater than about 256 so ... 194 */ 195 196 i = 8; 197 while (i < 1024 && i != msginfo.msgssz) 198 i <<= 1; 199 if (i != msginfo.msgssz) { 200 DPRINTF(("msginfo.msgssz=%d (0x%x)\n", msginfo.msgssz, 201 msginfo.msgssz)); 202 panic("msginfo.msgssz not a small power of 2"); 203 } 204 205 if (msginfo.msgseg > 32767) { 206 DPRINTF(("msginfo.msgseg=%d\n", msginfo.msgseg)); 207 panic("msginfo.msgseg > 32767"); 208 } 209 210 if (msgmaps == NULL) 211 panic("msgmaps is NULL"); 212 213 for (i = 0; i < msginfo.msgseg; i++) { 214 if (i > 0) 215 msgmaps[i-1].next = i; 216 msgmaps[i].next = -1; /* implies entry is available */ 217 } 218 free_msgmaps = 0; 219 nfree_msgmaps = msginfo.msgseg; 220 221 if (msghdrs == NULL) 222 panic("msghdrs is NULL"); 223 224 for (i = 0; i < msginfo.msgtql; i++) { 225 msghdrs[i].msg_type = 0; 226 if (i > 0) 227 msghdrs[i-1].msg_next = &msghdrs[i]; 228 msghdrs[i].msg_next = NULL; 229 #ifdef MAC 230 mac_init_sysv_msgmsg(&msghdrs[i]); 231 #endif 232 } 233 free_msghdrs = &msghdrs[0]; 234 235 if (msqids == NULL) 236 panic("msqids is NULL"); 237 238 for (i = 0; i < msginfo.msgmni; i++) { 239 msqids[i].u.msg_qbytes = 0; /* implies entry is available */ 240 msqids[i].u.msg_perm.seq = 0; /* reset to a known value */ 241 msqids[i].u.msg_perm.mode = 0; 242 #ifdef MAC 243 mac_init_sysv_msgqueue(&msqids[i]); 244 #endif 245 } 246 mtx_init(&msq_mtx, "msq", NULL, MTX_DEF); 247 } 248 249 static int 250 msgunload() 251 { 252 struct msqid_kernel *msqkptr; 253 int msqid; 254 #ifdef MAC 255 int i; 256 #endif 257 258 for (msqid = 0; msqid < msginfo.msgmni; msqid++) { 259 /* 260 * Look for an unallocated and unlocked msqid_ds. 261 * msqid_ds's can be locked by msgsnd or msgrcv while 262 * they are copying the message in/out. We can't 263 * re-use the entry until they release it. 264 */ 265 msqkptr = &msqids[msqid]; 266 if (msqkptr->u.msg_qbytes != 0 || 267 (msqkptr->u.msg_perm.mode & MSG_LOCKED) != 0) 268 break; 269 } 270 if (msqid != msginfo.msgmni) 271 return (EBUSY); 272 273 #ifdef MAC 274 for (i = 0; i < msginfo.msgtql; i++) 275 mac_destroy_sysv_msgmsg(&msghdrs[i]); 276 for (msqid = 0; msqid < msginfo.msgmni; msqid++) 277 mac_destroy_sysv_msgqueue(&msqids[msqid]); 278 #endif 279 free(msgpool, M_MSG); 280 free(msgmaps, M_MSG); 281 free(msghdrs, M_MSG); 282 free(msqids, M_MSG); 283 mtx_destroy(&msq_mtx); 284 return (0); 285 } 286 287 288 static int 289 sysvmsg_modload(struct module *module, int cmd, void *arg) 290 { 291 int error = 0; 292 293 switch (cmd) { 294 case MOD_LOAD: 295 msginit(); 296 break; 297 case MOD_UNLOAD: 298 error = msgunload(); 299 break; 300 case MOD_SHUTDOWN: 301 break; 302 default: 303 error = EINVAL; 304 break; 305 } 306 return (error); 307 } 308 309 static moduledata_t sysvmsg_mod = { 310 "sysvmsg", 311 &sysvmsg_modload, 312 NULL 313 }; 314 315 SYSCALL_MODULE_HELPER(msgsys); 316 SYSCALL_MODULE_HELPER(msgctl); 317 SYSCALL_MODULE_HELPER(msgget); 318 SYSCALL_MODULE_HELPER(msgsnd); 319 SYSCALL_MODULE_HELPER(msgrcv); 320 321 DECLARE_MODULE(sysvmsg, sysvmsg_mod, 322 SI_SUB_SYSV_MSG, SI_ORDER_FIRST); 323 MODULE_VERSION(sysvmsg, 1); 324 325 /* 326 * Entry point for all MSG calls 327 * 328 * MPSAFE 329 */ 330 int 331 msgsys(td, uap) 332 struct thread *td; 333 /* XXX actually varargs. */ 334 struct msgsys_args /* { 335 int which; 336 int a2; 337 int a3; 338 int a4; 339 int a5; 340 int a6; 341 } */ *uap; 342 { 343 int error; 344 345 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 346 return (ENOSYS); 347 if (uap->which < 0 || 348 uap->which >= sizeof(msgcalls)/sizeof(msgcalls[0])) 349 return (EINVAL); 350 error = (*msgcalls[uap->which])(td, &uap->a2); 351 return (error); 352 } 353 354 static void 355 msg_freehdr(msghdr) 356 struct msg *msghdr; 357 { 358 while (msghdr->msg_ts > 0) { 359 short next; 360 if (msghdr->msg_spot < 0 || msghdr->msg_spot >= msginfo.msgseg) 361 panic("msghdr->msg_spot out of range"); 362 next = msgmaps[msghdr->msg_spot].next; 363 msgmaps[msghdr->msg_spot].next = free_msgmaps; 364 free_msgmaps = msghdr->msg_spot; 365 nfree_msgmaps++; 366 msghdr->msg_spot = next; 367 if (msghdr->msg_ts >= msginfo.msgssz) 368 msghdr->msg_ts -= msginfo.msgssz; 369 else 370 msghdr->msg_ts = 0; 371 } 372 if (msghdr->msg_spot != -1) 373 panic("msghdr->msg_spot != -1"); 374 msghdr->msg_next = free_msghdrs; 375 free_msghdrs = msghdr; 376 #ifdef MAC 377 mac_cleanup_sysv_msgmsg(msghdr); 378 #endif 379 } 380 381 #ifndef _SYS_SYSPROTO_H_ 382 struct msgctl_args { 383 int msqid; 384 int cmd; 385 struct msqid_ds *buf; 386 }; 387 #endif 388 389 /* 390 * MPSAFE 391 */ 392 int 393 msgctl(td, uap) 394 struct thread *td; 395 register struct msgctl_args *uap; 396 { 397 int msqid = uap->msqid; 398 int cmd = uap->cmd; 399 struct msqid_ds msqbuf; 400 int error; 401 402 DPRINTF(("call to msgctl(%d, %d, %p)\n", msqid, cmd, uap->buf)); 403 if (cmd == IPC_SET && 404 (error = copyin(uap->buf, &msqbuf, sizeof(msqbuf))) != 0) 405 return (error); 406 error = kern_msgctl(td, msqid, cmd, &msqbuf); 407 if (cmd == IPC_STAT && error == 0) 408 error = copyout(&msqbuf, uap->buf, sizeof(struct msqid_ds)); 409 return (error); 410 } 411 412 int 413 kern_msgctl(td, msqid, cmd, msqbuf) 414 struct thread *td; 415 int msqid; 416 int cmd; 417 struct msqid_ds *msqbuf; 418 { 419 int rval, error, msqix; 420 register struct msqid_kernel *msqkptr; 421 422 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 423 return (ENOSYS); 424 425 msqix = IPCID_TO_IX(msqid); 426 427 if (msqix < 0 || msqix >= msginfo.msgmni) { 428 DPRINTF(("msqid (%d) out of range (0<=msqid<%d)\n", msqix, 429 msginfo.msgmni)); 430 return (EINVAL); 431 } 432 433 msqkptr = &msqids[msqix]; 434 435 mtx_lock(&msq_mtx); 436 if (msqkptr->u.msg_qbytes == 0) { 437 DPRINTF(("no such msqid\n")); 438 error = EINVAL; 439 goto done2; 440 } 441 if (msqkptr->u.msg_perm.seq != IPCID_TO_SEQ(msqid)) { 442 DPRINTF(("wrong sequence number\n")); 443 error = EINVAL; 444 goto done2; 445 } 446 #ifdef MAC 447 error = mac_check_sysv_msqctl(td->td_ucred, msqkptr, cmd); 448 if (error != 0) { 449 MPRINTF(("mac_check_sysv_msqctl returned %d\n", error)); 450 goto done2; 451 } 452 #endif 453 454 error = 0; 455 rval = 0; 456 457 switch (cmd) { 458 459 case IPC_RMID: 460 { 461 struct msg *msghdr; 462 if ((error = ipcperm(td, &msqkptr->u.msg_perm, IPC_M))) 463 goto done2; 464 465 #ifdef MAC 466 /* 467 * Check that the thread has MAC access permissions to 468 * individual msghdrs. Note: We need to do this in a 469 * separate loop because the actual loop alters the 470 * msq/msghdr info as it progresses, and there is no going 471 * back if half the way through we discover that the 472 * thread cannot free a certain msghdr. The msq will get 473 * into an inconsistent state. 474 */ 475 for (msghdr = msqkptr->u.msg_first; msghdr != NULL; 476 msghdr = msghdr->msg_next) { 477 error = mac_check_sysv_msgrmid(td->td_ucred, msghdr); 478 if (error != 0) { 479 MPRINTF(("mac_check_sysv_msgrmid returned %d\n", 480 error)); 481 goto done2; 482 } 483 } 484 #endif 485 486 /* Free the message headers */ 487 msghdr = msqkptr->u.msg_first; 488 while (msghdr != NULL) { 489 struct msg *msghdr_tmp; 490 491 /* Free the segments of each message */ 492 msqkptr->u.msg_cbytes -= msghdr->msg_ts; 493 msqkptr->u.msg_qnum--; 494 msghdr_tmp = msghdr; 495 msghdr = msghdr->msg_next; 496 msg_freehdr(msghdr_tmp); 497 } 498 499 if (msqkptr->u.msg_cbytes != 0) 500 panic("msg_cbytes is screwed up"); 501 if (msqkptr->u.msg_qnum != 0) 502 panic("msg_qnum is screwed up"); 503 504 msqkptr->u.msg_qbytes = 0; /* Mark it as free */ 505 506 #ifdef MAC 507 mac_cleanup_sysv_msgqueue(msqkptr); 508 #endif 509 510 wakeup(msqkptr); 511 } 512 513 break; 514 515 case IPC_SET: 516 if ((error = ipcperm(td, &msqkptr->u.msg_perm, IPC_M))) 517 goto done2; 518 if (msqbuf->msg_qbytes > msqkptr->u.msg_qbytes) { 519 error = suser(td); 520 if (error) 521 goto done2; 522 } 523 if (msqbuf->msg_qbytes > msginfo.msgmnb) { 524 DPRINTF(("can't increase msg_qbytes beyond %d" 525 "(truncating)\n", msginfo.msgmnb)); 526 msqbuf->msg_qbytes = msginfo.msgmnb; /* silently restrict qbytes to system limit */ 527 } 528 if (msqbuf->msg_qbytes == 0) { 529 DPRINTF(("can't reduce msg_qbytes to 0\n")); 530 error = EINVAL; /* non-standard errno! */ 531 goto done2; 532 } 533 msqkptr->u.msg_perm.uid = msqbuf->msg_perm.uid; /* change the owner */ 534 msqkptr->u.msg_perm.gid = msqbuf->msg_perm.gid; /* change the owner */ 535 msqkptr->u.msg_perm.mode = (msqkptr->u.msg_perm.mode & ~0777) | 536 (msqbuf->msg_perm.mode & 0777); 537 msqkptr->u.msg_qbytes = msqbuf->msg_qbytes; 538 msqkptr->u.msg_ctime = time_second; 539 break; 540 541 case IPC_STAT: 542 if ((error = ipcperm(td, &msqkptr->u.msg_perm, IPC_R))) { 543 DPRINTF(("requester doesn't have read access\n")); 544 goto done2; 545 } 546 *msqbuf = msqkptr->u; 547 break; 548 549 default: 550 DPRINTF(("invalid command %d\n", cmd)); 551 error = EINVAL; 552 goto done2; 553 } 554 555 if (error == 0) 556 td->td_retval[0] = rval; 557 done2: 558 mtx_unlock(&msq_mtx); 559 return (error); 560 } 561 562 #ifndef _SYS_SYSPROTO_H_ 563 struct msgget_args { 564 key_t key; 565 int msgflg; 566 }; 567 #endif 568 569 /* 570 * MPSAFE 571 */ 572 int 573 msgget(td, uap) 574 struct thread *td; 575 register struct msgget_args *uap; 576 { 577 int msqid, error = 0; 578 int key = uap->key; 579 int msgflg = uap->msgflg; 580 struct ucred *cred = td->td_ucred; 581 register struct msqid_kernel *msqkptr = NULL; 582 583 DPRINTF(("msgget(0x%x, 0%o)\n", key, msgflg)); 584 585 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 586 return (ENOSYS); 587 588 mtx_lock(&msq_mtx); 589 if (key != IPC_PRIVATE) { 590 for (msqid = 0; msqid < msginfo.msgmni; msqid++) { 591 msqkptr = &msqids[msqid]; 592 if (msqkptr->u.msg_qbytes != 0 && 593 msqkptr->u.msg_perm.key == key) 594 break; 595 } 596 if (msqid < msginfo.msgmni) { 597 DPRINTF(("found public key\n")); 598 if ((msgflg & IPC_CREAT) && (msgflg & IPC_EXCL)) { 599 DPRINTF(("not exclusive\n")); 600 error = EEXIST; 601 goto done2; 602 } 603 if ((error = ipcperm(td, &msqkptr->u.msg_perm, 604 msgflg & 0700))) { 605 DPRINTF(("requester doesn't have 0%o access\n", 606 msgflg & 0700)); 607 goto done2; 608 } 609 #ifdef MAC 610 error = mac_check_sysv_msqget(cred, msqkptr); 611 if (error != 0) { 612 MPRINTF(("mac_check_sysv_msqget returned %d\n", 613 error)); 614 goto done2; 615 } 616 #endif 617 goto found; 618 } 619 } 620 621 DPRINTF(("need to allocate the msqid_ds\n")); 622 if (key == IPC_PRIVATE || (msgflg & IPC_CREAT)) { 623 for (msqid = 0; msqid < msginfo.msgmni; msqid++) { 624 /* 625 * Look for an unallocated and unlocked msqid_ds. 626 * msqid_ds's can be locked by msgsnd or msgrcv while 627 * they are copying the message in/out. We can't 628 * re-use the entry until they release it. 629 */ 630 msqkptr = &msqids[msqid]; 631 if (msqkptr->u.msg_qbytes == 0 && 632 (msqkptr->u.msg_perm.mode & MSG_LOCKED) == 0) 633 break; 634 } 635 if (msqid == msginfo.msgmni) { 636 DPRINTF(("no more msqid_ds's available\n")); 637 error = ENOSPC; 638 goto done2; 639 } 640 DPRINTF(("msqid %d is available\n", msqid)); 641 msqkptr->u.msg_perm.key = key; 642 msqkptr->u.msg_perm.cuid = cred->cr_uid; 643 msqkptr->u.msg_perm.uid = cred->cr_uid; 644 msqkptr->u.msg_perm.cgid = cred->cr_gid; 645 msqkptr->u.msg_perm.gid = cred->cr_gid; 646 msqkptr->u.msg_perm.mode = (msgflg & 0777); 647 /* Make sure that the returned msqid is unique */ 648 msqkptr->u.msg_perm.seq = (msqkptr->u.msg_perm.seq + 1) & 0x7fff; 649 msqkptr->u.msg_first = NULL; 650 msqkptr->u.msg_last = NULL; 651 msqkptr->u.msg_cbytes = 0; 652 msqkptr->u.msg_qnum = 0; 653 msqkptr->u.msg_qbytes = msginfo.msgmnb; 654 msqkptr->u.msg_lspid = 0; 655 msqkptr->u.msg_lrpid = 0; 656 msqkptr->u.msg_stime = 0; 657 msqkptr->u.msg_rtime = 0; 658 msqkptr->u.msg_ctime = time_second; 659 #ifdef MAC 660 mac_create_sysv_msgqueue(cred, msqkptr); 661 #endif 662 } else { 663 DPRINTF(("didn't find it and wasn't asked to create it\n")); 664 error = ENOENT; 665 goto done2; 666 } 667 668 found: 669 /* Construct the unique msqid */ 670 td->td_retval[0] = IXSEQ_TO_IPCID(msqid, msqkptr->u.msg_perm); 671 done2: 672 mtx_unlock(&msq_mtx); 673 return (error); 674 } 675 676 #ifndef _SYS_SYSPROTO_H_ 677 struct msgsnd_args { 678 int msqid; 679 const void *msgp; 680 size_t msgsz; 681 int msgflg; 682 }; 683 #endif 684 685 int 686 kern_msgsnd(td, msqid, msgp, msgsz, msgflg, mtype) 687 struct thread *td; 688 int msqid; 689 const void *msgp; /* XXX msgp is actually mtext. */ 690 size_t msgsz; 691 int msgflg; 692 long mtype; 693 { 694 int msqix, segs_needed, error = 0; 695 register struct msqid_kernel *msqkptr; 696 register struct msg *msghdr; 697 short next; 698 699 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 700 return (ENOSYS); 701 702 mtx_lock(&msq_mtx); 703 msqix = IPCID_TO_IX(msqid); 704 705 if (msqix < 0 || msqix >= msginfo.msgmni) { 706 DPRINTF(("msqid (%d) out of range (0<=msqid<%d)\n", msqix, 707 msginfo.msgmni)); 708 error = EINVAL; 709 goto done2; 710 } 711 712 msqkptr = &msqids[msqix]; 713 if (msqkptr->u.msg_qbytes == 0) { 714 DPRINTF(("no such message queue id\n")); 715 error = EINVAL; 716 goto done2; 717 } 718 if (msqkptr->u.msg_perm.seq != IPCID_TO_SEQ(msqid)) { 719 DPRINTF(("wrong sequence number\n")); 720 error = EINVAL; 721 goto done2; 722 } 723 724 if ((error = ipcperm(td, &msqkptr->u.msg_perm, IPC_W))) { 725 DPRINTF(("requester doesn't have write access\n")); 726 goto done2; 727 } 728 729 #ifdef MAC 730 error = mac_check_sysv_msqsnd(td->td_ucred, msqkptr); 731 if (error != 0) { 732 MPRINTF(("mac_check_sysv_msqsnd returned %d\n", error)); 733 goto done2; 734 } 735 #endif 736 737 segs_needed = (msgsz + msginfo.msgssz - 1) / msginfo.msgssz; 738 DPRINTF(("msgsz=%zu, msgssz=%d, segs_needed=%d\n", msgsz, 739 msginfo.msgssz, segs_needed)); 740 for (;;) { 741 int need_more_resources = 0; 742 743 /* 744 * check msgsz 745 * (inside this loop in case msg_qbytes changes while we sleep) 746 */ 747 748 if (msgsz > msqkptr->u.msg_qbytes) { 749 DPRINTF(("msgsz > msqkptr->u.msg_qbytes\n")); 750 error = EINVAL; 751 goto done2; 752 } 753 754 if (msqkptr->u.msg_perm.mode & MSG_LOCKED) { 755 DPRINTF(("msqid is locked\n")); 756 need_more_resources = 1; 757 } 758 if (msgsz + msqkptr->u.msg_cbytes > msqkptr->u.msg_qbytes) { 759 DPRINTF(("msgsz + msg_cbytes > msg_qbytes\n")); 760 need_more_resources = 1; 761 } 762 if (segs_needed > nfree_msgmaps) { 763 DPRINTF(("segs_needed > nfree_msgmaps\n")); 764 need_more_resources = 1; 765 } 766 if (free_msghdrs == NULL) { 767 DPRINTF(("no more msghdrs\n")); 768 need_more_resources = 1; 769 } 770 771 if (need_more_resources) { 772 int we_own_it; 773 774 if ((msgflg & IPC_NOWAIT) != 0) { 775 DPRINTF(("need more resources but caller " 776 "doesn't want to wait\n")); 777 error = EAGAIN; 778 goto done2; 779 } 780 781 if ((msqkptr->u.msg_perm.mode & MSG_LOCKED) != 0) { 782 DPRINTF(("we don't own the msqid_ds\n")); 783 we_own_it = 0; 784 } else { 785 /* Force later arrivals to wait for our 786 request */ 787 DPRINTF(("we own the msqid_ds\n")); 788 msqkptr->u.msg_perm.mode |= MSG_LOCKED; 789 we_own_it = 1; 790 } 791 DPRINTF(("goodnight\n")); 792 error = msleep(msqkptr, &msq_mtx, (PZERO - 4) | PCATCH, 793 "msgwait", 0); 794 DPRINTF(("good morning, error=%d\n", error)); 795 if (we_own_it) 796 msqkptr->u.msg_perm.mode &= ~MSG_LOCKED; 797 if (error != 0) { 798 DPRINTF(("msgsnd: interrupted system call\n")); 799 error = EINTR; 800 goto done2; 801 } 802 803 /* 804 * Make sure that the msq queue still exists 805 */ 806 807 if (msqkptr->u.msg_qbytes == 0) { 808 DPRINTF(("msqid deleted\n")); 809 error = EIDRM; 810 goto done2; 811 } 812 813 } else { 814 DPRINTF(("got all the resources that we need\n")); 815 break; 816 } 817 } 818 819 /* 820 * We have the resources that we need. 821 * Make sure! 822 */ 823 824 if (msqkptr->u.msg_perm.mode & MSG_LOCKED) 825 panic("msg_perm.mode & MSG_LOCKED"); 826 if (segs_needed > nfree_msgmaps) 827 panic("segs_needed > nfree_msgmaps"); 828 if (msgsz + msqkptr->u.msg_cbytes > msqkptr->u.msg_qbytes) 829 panic("msgsz + msg_cbytes > msg_qbytes"); 830 if (free_msghdrs == NULL) 831 panic("no more msghdrs"); 832 833 /* 834 * Re-lock the msqid_ds in case we page-fault when copying in the 835 * message 836 */ 837 838 if ((msqkptr->u.msg_perm.mode & MSG_LOCKED) != 0) 839 panic("msqid_ds is already locked"); 840 msqkptr->u.msg_perm.mode |= MSG_LOCKED; 841 842 /* 843 * Allocate a message header 844 */ 845 846 msghdr = free_msghdrs; 847 free_msghdrs = msghdr->msg_next; 848 msghdr->msg_spot = -1; 849 msghdr->msg_ts = msgsz; 850 msghdr->msg_type = mtype; 851 #ifdef MAC 852 /* 853 * XXXMAC: Should the mac_check_sysv_msgmsq check follow here 854 * immediately? Or, should it be checked just before the msg is 855 * enqueued in the msgq (as it is done now)? 856 */ 857 mac_create_sysv_msgmsg(td->td_ucred, msqkptr, msghdr); 858 #endif 859 860 /* 861 * Allocate space for the message 862 */ 863 864 while (segs_needed > 0) { 865 if (nfree_msgmaps <= 0) 866 panic("not enough msgmaps"); 867 if (free_msgmaps == -1) 868 panic("nil free_msgmaps"); 869 next = free_msgmaps; 870 if (next <= -1) 871 panic("next too low #1"); 872 if (next >= msginfo.msgseg) 873 panic("next out of range #1"); 874 DPRINTF(("allocating segment %d to message\n", next)); 875 free_msgmaps = msgmaps[next].next; 876 nfree_msgmaps--; 877 msgmaps[next].next = msghdr->msg_spot; 878 msghdr->msg_spot = next; 879 segs_needed--; 880 } 881 882 /* 883 * Validate the message type 884 */ 885 886 if (msghdr->msg_type < 1) { 887 msg_freehdr(msghdr); 888 msqkptr->u.msg_perm.mode &= ~MSG_LOCKED; 889 wakeup(msqkptr); 890 DPRINTF(("mtype (%ld) < 1\n", msghdr->msg_type)); 891 error = EINVAL; 892 goto done2; 893 } 894 895 /* 896 * Copy in the message body 897 */ 898 899 next = msghdr->msg_spot; 900 while (msgsz > 0) { 901 size_t tlen; 902 if (msgsz > msginfo.msgssz) 903 tlen = msginfo.msgssz; 904 else 905 tlen = msgsz; 906 if (next <= -1) 907 panic("next too low #2"); 908 if (next >= msginfo.msgseg) 909 panic("next out of range #2"); 910 mtx_unlock(&msq_mtx); 911 if ((error = copyin(msgp, &msgpool[next * msginfo.msgssz], 912 tlen)) != 0) { 913 mtx_lock(&msq_mtx); 914 DPRINTF(("error %d copying in message segment\n", 915 error)); 916 msg_freehdr(msghdr); 917 msqkptr->u.msg_perm.mode &= ~MSG_LOCKED; 918 wakeup(msqkptr); 919 goto done2; 920 } 921 mtx_lock(&msq_mtx); 922 msgsz -= tlen; 923 msgp = (const char *)msgp + tlen; 924 next = msgmaps[next].next; 925 } 926 if (next != -1) 927 panic("didn't use all the msg segments"); 928 929 /* 930 * We've got the message. Unlock the msqid_ds. 931 */ 932 933 msqkptr->u.msg_perm.mode &= ~MSG_LOCKED; 934 935 /* 936 * Make sure that the msqid_ds is still allocated. 937 */ 938 939 if (msqkptr->u.msg_qbytes == 0) { 940 msg_freehdr(msghdr); 941 wakeup(msqkptr); 942 error = EIDRM; 943 goto done2; 944 } 945 946 #ifdef MAC 947 /* 948 * Note: Since the task/thread allocates the msghdr and usually 949 * primes it with its own MAC label, for a majority of policies, it 950 * won't be necessary to check whether the msghdr has access 951 * permissions to the msgq. The mac_check_sysv_msqsnd check would 952 * suffice in that case. However, this hook may be required where 953 * individual policies derive a non-identical label for the msghdr 954 * from the current thread label and may want to check the msghdr 955 * enqueue permissions, along with read/write permissions to the 956 * msgq. 957 */ 958 error = mac_check_sysv_msgmsq(td->td_ucred, msghdr, msqkptr); 959 if (error != 0) { 960 MPRINTF(("mac_check_sysv_msqmsq returned %d\n", error)); 961 msg_freehdr(msghdr); 962 wakeup(msqkptr); 963 goto done2; 964 } 965 #endif 966 967 /* 968 * Put the message into the queue 969 */ 970 if (msqkptr->u.msg_first == NULL) { 971 msqkptr->u.msg_first = msghdr; 972 msqkptr->u.msg_last = msghdr; 973 } else { 974 msqkptr->u.msg_last->msg_next = msghdr; 975 msqkptr->u.msg_last = msghdr; 976 } 977 msqkptr->u.msg_last->msg_next = NULL; 978 979 msqkptr->u.msg_cbytes += msghdr->msg_ts; 980 msqkptr->u.msg_qnum++; 981 msqkptr->u.msg_lspid = td->td_proc->p_pid; 982 msqkptr->u.msg_stime = time_second; 983 984 wakeup(msqkptr); 985 td->td_retval[0] = 0; 986 done2: 987 mtx_unlock(&msq_mtx); 988 return (error); 989 } 990 991 /* 992 * MPSAFE 993 */ 994 int 995 msgsnd(td, uap) 996 struct thread *td; 997 register struct msgsnd_args *uap; 998 { 999 int error; 1000 long mtype; 1001 1002 DPRINTF(("call to msgsnd(%d, %p, %zu, %d)\n", uap->msqid, uap->msgp, 1003 uap->msgsz, uap->msgflg)); 1004 1005 if ((error = copyin(uap->msgp, &mtype, sizeof(mtype))) != 0) { 1006 DPRINTF(("error %d copying the message type\n", error)); 1007 return (error); 1008 } 1009 return (kern_msgsnd(td, uap->msqid, 1010 (const char *)uap->msgp + sizeof(mtype), 1011 uap->msgsz, uap->msgflg, mtype)); 1012 } 1013 1014 #ifndef _SYS_SYSPROTO_H_ 1015 struct msgrcv_args { 1016 int msqid; 1017 void *msgp; 1018 size_t msgsz; 1019 long msgtyp; 1020 int msgflg; 1021 }; 1022 #endif 1023 1024 int 1025 kern_msgrcv(td, msqid, msgp, msgsz, msgtyp, msgflg, mtype) 1026 struct thread *td; 1027 int msqid; 1028 void *msgp; /* XXX msgp is actually mtext. */ 1029 size_t msgsz; 1030 long msgtyp; 1031 int msgflg; 1032 long *mtype; 1033 { 1034 size_t len; 1035 register struct msqid_kernel *msqkptr; 1036 register struct msg *msghdr; 1037 int msqix, error = 0; 1038 short next; 1039 1040 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 1041 return (ENOSYS); 1042 1043 msqix = IPCID_TO_IX(msqid); 1044 1045 if (msqix < 0 || msqix >= msginfo.msgmni) { 1046 DPRINTF(("msqid (%d) out of range (0<=msqid<%d)\n", msqix, 1047 msginfo.msgmni)); 1048 return (EINVAL); 1049 } 1050 1051 msqkptr = &msqids[msqix]; 1052 mtx_lock(&msq_mtx); 1053 if (msqkptr->u.msg_qbytes == 0) { 1054 DPRINTF(("no such message queue id\n")); 1055 error = EINVAL; 1056 goto done2; 1057 } 1058 if (msqkptr->u.msg_perm.seq != IPCID_TO_SEQ(msqid)) { 1059 DPRINTF(("wrong sequence number\n")); 1060 error = EINVAL; 1061 goto done2; 1062 } 1063 1064 if ((error = ipcperm(td, &msqkptr->u.msg_perm, IPC_R))) { 1065 DPRINTF(("requester doesn't have read access\n")); 1066 goto done2; 1067 } 1068 1069 #ifdef MAC 1070 error = mac_check_sysv_msqrcv(td->td_ucred, msqkptr); 1071 if (error != 0) { 1072 MPRINTF(("mac_check_sysv_msqrcv returned %d\n", error)); 1073 goto done2; 1074 } 1075 #endif 1076 1077 msghdr = NULL; 1078 while (msghdr == NULL) { 1079 if (msgtyp == 0) { 1080 msghdr = msqkptr->u.msg_first; 1081 if (msghdr != NULL) { 1082 if (msgsz < msghdr->msg_ts && 1083 (msgflg & MSG_NOERROR) == 0) { 1084 DPRINTF(("first message on the queue " 1085 "is too big (want %zu, got %d)\n", 1086 msgsz, msghdr->msg_ts)); 1087 error = E2BIG; 1088 goto done2; 1089 } 1090 #ifdef MAC 1091 error = mac_check_sysv_msgrcv(td->td_ucred, 1092 msghdr); 1093 if (error != 0) { 1094 MPRINTF(("mac_check_sysv_msgrcv " 1095 "returned %d\n", error)); 1096 goto done2; 1097 } 1098 #endif 1099 if (msqkptr->u.msg_first == msqkptr->u.msg_last) { 1100 msqkptr->u.msg_first = NULL; 1101 msqkptr->u.msg_last = NULL; 1102 } else { 1103 msqkptr->u.msg_first = msghdr->msg_next; 1104 if (msqkptr->u.msg_first == NULL) 1105 panic("msg_first/last screwed up #1"); 1106 } 1107 } 1108 } else { 1109 struct msg *previous; 1110 struct msg **prev; 1111 1112 previous = NULL; 1113 prev = &(msqkptr->u.msg_first); 1114 while ((msghdr = *prev) != NULL) { 1115 /* 1116 * Is this message's type an exact match or is 1117 * this message's type less than or equal to 1118 * the absolute value of a negative msgtyp? 1119 * Note that the second half of this test can 1120 * NEVER be true if msgtyp is positive since 1121 * msg_type is always positive! 1122 */ 1123 1124 if (msgtyp == msghdr->msg_type || 1125 msghdr->msg_type <= -msgtyp) { 1126 DPRINTF(("found message type %ld, " 1127 "requested %ld\n", 1128 msghdr->msg_type, msgtyp)); 1129 if (msgsz < msghdr->msg_ts && 1130 (msgflg & MSG_NOERROR) == 0) { 1131 DPRINTF(("requested message " 1132 "on the queue is too big " 1133 "(want %zu, got %hu)\n", 1134 msgsz, msghdr->msg_ts)); 1135 error = E2BIG; 1136 goto done2; 1137 } 1138 #ifdef MAC 1139 error = mac_check_sysv_msgrcv( 1140 td->td_ucred, msghdr); 1141 if (error != 0) { 1142 MPRINTF(("mac_check_sysv_" 1143 "msgrcv returned %d\n", 1144 error)); 1145 goto done2; 1146 } 1147 #endif 1148 *prev = msghdr->msg_next; 1149 if (msghdr == msqkptr->u.msg_last) { 1150 if (previous == NULL) { 1151 if (prev != 1152 &msqkptr->u.msg_first) 1153 panic("msg_first/last screwed up #2"); 1154 msqkptr->u.msg_first = 1155 NULL; 1156 msqkptr->u.msg_last = 1157 NULL; 1158 } else { 1159 if (prev == 1160 &msqkptr->u.msg_first) 1161 panic("msg_first/last screwed up #3"); 1162 msqkptr->u.msg_last = 1163 previous; 1164 } 1165 } 1166 break; 1167 } 1168 previous = msghdr; 1169 prev = &(msghdr->msg_next); 1170 } 1171 } 1172 1173 /* 1174 * We've either extracted the msghdr for the appropriate 1175 * message or there isn't one. 1176 * If there is one then bail out of this loop. 1177 */ 1178 1179 if (msghdr != NULL) 1180 break; 1181 1182 /* 1183 * Hmph! No message found. Does the user want to wait? 1184 */ 1185 1186 if ((msgflg & IPC_NOWAIT) != 0) { 1187 DPRINTF(("no appropriate message found (msgtyp=%ld)\n", 1188 msgtyp)); 1189 /* The SVID says to return ENOMSG. */ 1190 error = ENOMSG; 1191 goto done2; 1192 } 1193 1194 /* 1195 * Wait for something to happen 1196 */ 1197 1198 DPRINTF(("msgrcv: goodnight\n")); 1199 error = msleep(msqkptr, &msq_mtx, (PZERO - 4) | PCATCH, 1200 "msgwait", 0); 1201 DPRINTF(("msgrcv: good morning (error=%d)\n", error)); 1202 1203 if (error != 0) { 1204 DPRINTF(("msgsnd: interrupted system call\n")); 1205 error = EINTR; 1206 goto done2; 1207 } 1208 1209 /* 1210 * Make sure that the msq queue still exists 1211 */ 1212 1213 if (msqkptr->u.msg_qbytes == 0 || 1214 msqkptr->u.msg_perm.seq != IPCID_TO_SEQ(msqid)) { 1215 DPRINTF(("msqid deleted\n")); 1216 error = EIDRM; 1217 goto done2; 1218 } 1219 } 1220 1221 /* 1222 * Return the message to the user. 1223 * 1224 * First, do the bookkeeping (before we risk being interrupted). 1225 */ 1226 1227 msqkptr->u.msg_cbytes -= msghdr->msg_ts; 1228 msqkptr->u.msg_qnum--; 1229 msqkptr->u.msg_lrpid = td->td_proc->p_pid; 1230 msqkptr->u.msg_rtime = time_second; 1231 1232 /* 1233 * Make msgsz the actual amount that we'll be returning. 1234 * Note that this effectively truncates the message if it is too long 1235 * (since msgsz is never increased). 1236 */ 1237 1238 DPRINTF(("found a message, msgsz=%zu, msg_ts=%hu\n", msgsz, 1239 msghdr->msg_ts)); 1240 if (msgsz > msghdr->msg_ts) 1241 msgsz = msghdr->msg_ts; 1242 *mtype = msghdr->msg_type; 1243 1244 /* 1245 * Return the segments to the user 1246 */ 1247 1248 next = msghdr->msg_spot; 1249 for (len = 0; len < msgsz; len += msginfo.msgssz) { 1250 size_t tlen; 1251 1252 if (msgsz - len > msginfo.msgssz) 1253 tlen = msginfo.msgssz; 1254 else 1255 tlen = msgsz - len; 1256 if (next <= -1) 1257 panic("next too low #3"); 1258 if (next >= msginfo.msgseg) 1259 panic("next out of range #3"); 1260 mtx_unlock(&msq_mtx); 1261 error = copyout(&msgpool[next * msginfo.msgssz], msgp, tlen); 1262 mtx_lock(&msq_mtx); 1263 if (error != 0) { 1264 DPRINTF(("error (%d) copying out message segment\n", 1265 error)); 1266 msg_freehdr(msghdr); 1267 wakeup(msqkptr); 1268 goto done2; 1269 } 1270 msgp = (char *)msgp + tlen; 1271 next = msgmaps[next].next; 1272 } 1273 1274 /* 1275 * Done, return the actual number of bytes copied out. 1276 */ 1277 1278 msg_freehdr(msghdr); 1279 wakeup(msqkptr); 1280 td->td_retval[0] = msgsz; 1281 done2: 1282 mtx_unlock(&msq_mtx); 1283 return (error); 1284 } 1285 1286 /* 1287 * MPSAFE 1288 */ 1289 int 1290 msgrcv(td, uap) 1291 struct thread *td; 1292 register struct msgrcv_args *uap; 1293 { 1294 int error; 1295 long mtype; 1296 1297 DPRINTF(("call to msgrcv(%d, %p, %zu, %ld, %d)\n", uap->msqid, 1298 uap->msgp, uap->msgsz, uap->msgtyp, uap->msgflg)); 1299 1300 if ((error = kern_msgrcv(td, uap->msqid, 1301 (char *)uap->msgp + sizeof(mtype), uap->msgsz, 1302 uap->msgtyp, uap->msgflg, &mtype)) != 0) 1303 return (error); 1304 if ((error = copyout(&mtype, uap->msgp, sizeof(mtype))) != 0) 1305 DPRINTF(("error %d copying the message type\n", error)); 1306 return (error); 1307 } 1308 1309 static int 1310 sysctl_msqids(SYSCTL_HANDLER_ARGS) 1311 { 1312 1313 return (SYSCTL_OUT(req, msqids, 1314 sizeof(struct msqid_kernel) * msginfo.msgmni)); 1315 } 1316 1317 SYSCTL_DECL(_kern_ipc); 1318 SYSCTL_INT(_kern_ipc, OID_AUTO, msgmax, CTLFLAG_RD, &msginfo.msgmax, 0, 1319 "Maximum message size"); 1320 SYSCTL_INT(_kern_ipc, OID_AUTO, msgmni, CTLFLAG_RDTUN, &msginfo.msgmni, 0, 1321 "Number of message queue identifiers"); 1322 SYSCTL_INT(_kern_ipc, OID_AUTO, msgmnb, CTLFLAG_RDTUN, &msginfo.msgmnb, 0, 1323 "Maximum number of bytes in a queue"); 1324 SYSCTL_INT(_kern_ipc, OID_AUTO, msgtql, CTLFLAG_RDTUN, &msginfo.msgtql, 0, 1325 "Maximum number of messages in the system"); 1326 SYSCTL_INT(_kern_ipc, OID_AUTO, msgssz, CTLFLAG_RDTUN, &msginfo.msgssz, 0, 1327 "Size of a message segment"); 1328 SYSCTL_INT(_kern_ipc, OID_AUTO, msgseg, CTLFLAG_RDTUN, &msginfo.msgseg, 0, 1329 "Number of message segments"); 1330 SYSCTL_PROC(_kern_ipc, OID_AUTO, msqids, CTLFLAG_RD, 1331 NULL, 0, sysctl_msqids, "", "Message queue IDs");
Cache object: de4b23c5d3c0c4c0a3c1421069b7ad60
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