1/* $NetBSD: sysv_sem.c,v 1.98 2019/08/07 00:38:02 pgoyette Exp $ */ 2 3/*- 4 * Copyright (c) 1999, 2007 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, 9 * NASA Ames Research Center, and by Andrew Doran. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 23 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 24 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 30 * POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33/* 34 * Implementation of SVID semaphores 35 * 36 * Author: Daniel Boulet 37 * 38 * This software is provided ``AS IS'' without any warranties of any kind. 39 */ 40 41#include <sys/cdefs.h> 42__KERNEL_RCSID(0, "$NetBSD: sysv_sem.c,v 1.98 2019/08/07 00:38:02 pgoyette Exp $"); 43 44#ifdef _KERNEL_OPT 45#include "opt_sysv.h" 46#endif 47 48#include <sys/param.h> 49#include <sys/kernel.h> 50#include <sys/sem.h> 51#include <sys/sysctl.h> 52#include <sys/kmem.h> 53#include <sys/mount.h> /* XXX for <sys/syscallargs.h> */ 54#include <sys/syscallargs.h> 55#include <sys/kauth.h> 56#include <sys/once.h> 57 58/* 59 * Memory areas: 60 * 1st: Pool of semaphore identifiers 61 * 2nd: Semaphores 62 * 3rd: Conditional variables 63 * 4th: Undo structures 64 */ 65struct semid_ds * sema __read_mostly; 66static struct __sem * sem __read_mostly; 67static kcondvar_t * semcv __read_mostly; 68static int * semu __read_mostly; 69 70static kmutex_t semlock __cacheline_aligned; 71static bool sem_realloc_state __read_mostly; 72static kcondvar_t sem_realloc_cv; 73 74/* 75 * List of active undo structures, total number of semaphores, 76 * and total number of semop waiters. 77 */ 78static struct sem_undo *semu_list __read_mostly; 79static u_int semtot __cacheline_aligned; 80static u_int sem_waiters __cacheline_aligned; 81 82/* Macro to find a particular sem_undo vector */ 83#define SEMU(s, ix) ((struct sem_undo *)(((long)s) + ix * seminfo.semusz)) 84 85#ifdef SEM_DEBUG 86#define SEM_PRINTF(a) printf a 87#else 88#define SEM_PRINTF(a) 89#endif 90 91void *hook; /* cookie from exithook_establish() */ 92 93extern int kern_has_sysvsem; 94 95SYSCTL_SETUP_PROTO(sysctl_ipc_sem_setup); 96 97struct sem_undo *semu_alloc(struct proc *); 98int semundo_adjust(struct proc *, struct sem_undo **, int, int, int); 99void semundo_clear(int, int); 100 101static ONCE_DECL(exithook_control); 102static int seminit_exithook(void); 103 104int 105seminit(void) 106{ 107 int i, sz; 108 vaddr_t v; 109 110 mutex_init(&semlock, MUTEX_DEFAULT, IPL_NONE); 111 cv_init(&sem_realloc_cv, "semrealc"); 112 sem_realloc_state = false; 113 semtot = 0; 114 sem_waiters = 0; 115 116 /* Allocate the wired memory for our structures */ 117 sz = ALIGN(seminfo.semmni * sizeof(struct semid_ds)) + 118 ALIGN(seminfo.semmns * sizeof(struct __sem)) + 119 ALIGN(seminfo.semmni * sizeof(kcondvar_t)) + 120 ALIGN(seminfo.semmnu * seminfo.semusz); 121 sz = round_page(sz); 122 v = uvm_km_alloc(kernel_map, sz, 0, UVM_KMF_WIRED|UVM_KMF_ZERO); 123 if (v == 0) { 124 printf("sysv_sem: cannot allocate memory"); 125 return ENOMEM; 126 } 127 sema = (void *)v; 128 sem = (void *)((uintptr_t)sema + 129 ALIGN(seminfo.semmni * sizeof(struct semid_ds))); 130 semcv = (void *)((uintptr_t)sem + 131 ALIGN(seminfo.semmns * sizeof(struct __sem))); 132 semu = (void *)((uintptr_t)semcv + 133 ALIGN(seminfo.semmni * sizeof(kcondvar_t))); 134 135 for (i = 0; i < seminfo.semmni; i++) { 136 sema[i]._sem_base = 0; 137 sema[i].sem_perm.mode = 0; 138 cv_init(&semcv[i], "semwait"); 139 } 140 for (i = 0; i < seminfo.semmnu; i++) { 141 struct sem_undo *suptr = SEMU(semu, i); 142 suptr->un_proc = NULL; 143 } 144 semu_list = NULL; 145 146 kern_has_sysvsem = 1; 147 148 return 0; 149} 150 151static int 152seminit_exithook(void) 153{ 154 155 hook = exithook_establish(semexit, NULL); 156 return 0; 157} 158 159int 160semfini(void) 161{ 162 int i, sz; 163 vaddr_t v = (vaddr_t)sema; 164 165 /* Don't allow module unload if we're busy */ 166 mutex_enter(&semlock); 167 if (semtot) { 168 mutex_exit(&semlock); 169 return 1; 170 } 171 172 /* Remove the exit hook */ 173 if (hook) 174 exithook_disestablish(hook); 175 176 /* Destroy all our condvars */ 177 for (i = 0; i < seminfo.semmni; i++) { 178 cv_destroy(&semcv[i]); 179 } 180 181 /* Free the wired memory that we allocated */ 182 sz = ALIGN(seminfo.semmni * sizeof(struct semid_ds)) + 183 ALIGN(seminfo.semmns * sizeof(struct __sem)) + 184 ALIGN(seminfo.semmni * sizeof(kcondvar_t)) + 185 ALIGN(seminfo.semmnu * seminfo.semusz); 186 sz = round_page(sz); 187 uvm_km_free(kernel_map, v, sz, UVM_KMF_WIRED); 188 189 /* Destroy the last cv and mutex */ 190 cv_destroy(&sem_realloc_cv); 191 mutex_exit(&semlock); 192 mutex_destroy(&semlock); 193 194 kern_has_sysvsem = 0; 195 196 return 0; 197} 198 199static int 200semrealloc(int newsemmni, int newsemmns, int newsemmnu) 201{ 202 struct semid_ds *new_sema, *old_sema; 203 struct __sem *new_sem; 204 struct sem_undo *new_semu_list, *suptr, *nsuptr; 205 int *new_semu; 206 kcondvar_t *new_semcv; 207 vaddr_t v; 208 int i, j, lsemid, nmnus, sz; 209 210 if (newsemmni < 1 || newsemmns < 1 || newsemmnu < 1) 211 return EINVAL; 212 213 /* Allocate the wired memory for our structures */ 214 sz = ALIGN(newsemmni * sizeof(struct semid_ds)) + 215 ALIGN(newsemmns * sizeof(struct __sem)) + 216 ALIGN(newsemmni * sizeof(kcondvar_t)) + 217 ALIGN(newsemmnu * seminfo.semusz); 218 sz = round_page(sz); 219 v = uvm_km_alloc(kernel_map, sz, 0, UVM_KMF_WIRED|UVM_KMF_ZERO); 220 if (v == 0) 221 return ENOMEM; 222 223 mutex_enter(&semlock); 224 if (sem_realloc_state) { 225 mutex_exit(&semlock); 226 uvm_km_free(kernel_map, v, sz, UVM_KMF_WIRED); 227 return EBUSY; 228 } 229 sem_realloc_state = true; 230 if (sem_waiters) { 231 /* 232 * Mark reallocation state, wake-up all waiters, 233 * and wait while they will all exit. 234 */ 235 for (i = 0; i < seminfo.semmni; i++) 236 cv_broadcast(&semcv[i]); 237 while (sem_waiters) 238 cv_wait(&sem_realloc_cv, &semlock); 239 } 240 old_sema = sema; 241 242 /* Get the number of last slot */ 243 lsemid = 0; 244 for (i = 0; i < seminfo.semmni; i++) 245 if (sema[i].sem_perm.mode & SEM_ALLOC) 246 lsemid = i; 247 248 /* Get the number of currently used undo structures */ 249 nmnus = 0; 250 for (i = 0; i < seminfo.semmnu; i++) { 251 suptr = SEMU(semu, i); 252 if (suptr->un_proc == NULL) 253 continue; 254 nmnus++; 255 } 256 257 /* We cannot reallocate less memory than we use */ 258 if (lsemid >= newsemmni || semtot > newsemmns || nmnus > newsemmnu) { 259 mutex_exit(&semlock); 260 uvm_km_free(kernel_map, v, sz, UVM_KMF_WIRED); 261 return EBUSY; 262 } 263 264 new_sema = (void *)v; 265 new_sem = (void *)((uintptr_t)new_sema + 266 ALIGN(newsemmni * sizeof(struct semid_ds))); 267 new_semcv = (void *)((uintptr_t)new_sem + 268 ALIGN(newsemmns * sizeof(struct __sem))); 269 new_semu = (void *)((uintptr_t)new_semcv + 270 ALIGN(newsemmni * sizeof(kcondvar_t))); 271 272 /* Initialize all semaphore identifiers and condvars */ 273 for (i = 0; i < newsemmni; i++) { 274 new_sema[i]._sem_base = 0; 275 new_sema[i].sem_perm.mode = 0; 276 cv_init(&new_semcv[i], "semwait"); 277 } 278 for (i = 0; i < newsemmnu; i++) { 279 nsuptr = SEMU(new_semu, i); 280 nsuptr->un_proc = NULL; 281 } 282 283 /* 284 * Copy all identifiers, semaphores and list of the 285 * undo structures to the new memory allocation. 286 */ 287 j = 0; 288 for (i = 0; i <= lsemid; i++) { 289 if ((sema[i].sem_perm.mode & SEM_ALLOC) == 0) 290 continue; 291 memcpy(&new_sema[i], &sema[i], sizeof(struct semid_ds)); 292 new_sema[i]._sem_base = &new_sem[j]; 293 memcpy(new_sema[i]._sem_base, sema[i]._sem_base, 294 (sizeof(struct __sem) * sema[i].sem_nsems)); 295 j += sema[i].sem_nsems; 296 } 297 KASSERT(j == semtot); 298 299 j = 0; 300 new_semu_list = NULL; 301 for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) { 302 KASSERT(j < newsemmnu); 303 nsuptr = SEMU(new_semu, j); 304 memcpy(nsuptr, suptr, SEMUSZ); 305 nsuptr->un_next = new_semu_list; 306 new_semu_list = nsuptr; 307 j++; 308 } 309 310 for (i = 0; i < seminfo.semmni; i++) { 311 KASSERT(cv_has_waiters(&semcv[i]) == false); 312 cv_destroy(&semcv[i]); 313 } 314 315 sz = ALIGN(seminfo.semmni * sizeof(struct semid_ds)) + 316 ALIGN(seminfo.semmns * sizeof(struct __sem)) + 317 ALIGN(seminfo.semmni * sizeof(kcondvar_t)) + 318 ALIGN(seminfo.semmnu * seminfo.semusz); 319 sz = round_page(sz); 320 321 /* Set the pointers and update the new values */ 322 sema = new_sema; 323 sem = new_sem; 324 semcv = new_semcv; 325 semu = new_semu; 326 semu_list = new_semu_list; 327 328 seminfo.semmni = newsemmni; 329 seminfo.semmns = newsemmns; 330 seminfo.semmnu = newsemmnu; 331 332 /* Reallocation completed - notify all waiters, if any */ 333 sem_realloc_state = false; 334 cv_broadcast(&sem_realloc_cv); 335 mutex_exit(&semlock); 336 337 uvm_km_free(kernel_map, (vaddr_t)old_sema, sz, UVM_KMF_WIRED); 338 return 0; 339} 340 341/* 342 * Placebo. 343 */ 344 345int 346sys_semconfig(struct lwp *l, const struct sys_semconfig_args *uap, register_t *retval) 347{ 348 349 RUN_ONCE(&exithook_control, seminit_exithook); 350 351 *retval = 0; 352 return 0; 353} 354 355/* 356 * Allocate a new sem_undo structure for a process. 357 * => Returns NULL on failure. 358 */ 359struct sem_undo * 360semu_alloc(struct proc *p) 361{ 362 struct sem_undo *suptr, **supptr; 363 bool attempted = false; 364 int i; 365 366 KASSERT(mutex_owned(&semlock)); 367again: 368 /* Look for a free structure. */ 369 for (i = 0; i < seminfo.semmnu; i++) { 370 suptr = SEMU(semu, i); 371 if (suptr->un_proc == NULL) { 372 /* Found. Fill it in and return. */ 373 suptr->un_next = semu_list; 374 semu_list = suptr; 375 suptr->un_cnt = 0; 376 suptr->un_proc = p; 377 return suptr; 378 } 379 } 380 381 /* Not found. Attempt to free some structures. */ 382 if (!attempted) { 383 bool freed = false; 384 385 attempted = true; 386 supptr = &semu_list; 387 while ((suptr = *supptr) != NULL) { 388 if (suptr->un_cnt == 0) { 389 suptr->un_proc = NULL; 390 *supptr = suptr->un_next; 391 freed = true; 392 } else { 393 supptr = &suptr->un_next; 394 } 395 } 396 if (freed) { 397 goto again; 398 } 399 } 400 return NULL; 401} 402 403/* 404 * Adjust a particular entry for a particular proc 405 */ 406 407int 408semundo_adjust(struct proc *p, struct sem_undo **supptr, int semid, int semnum, 409 int adjval) 410{ 411 struct sem_undo *suptr; 412 struct sem_undo_entry *sunptr; 413 int i; 414 415 KASSERT(mutex_owned(&semlock)); 416 417 /* 418 * Look for and remember the sem_undo if the caller doesn't 419 * provide it 420 */ 421 422 suptr = *supptr; 423 if (suptr == NULL) { 424 for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) 425 if (suptr->un_proc == p) 426 break; 427 428 if (suptr == NULL) { 429 suptr = semu_alloc(p); 430 if (suptr == NULL) 431 return (ENOSPC); 432 } 433 *supptr = suptr; 434 } 435 436 /* 437 * Look for the requested entry and adjust it (delete if 438 * adjval becomes 0). 439 */ 440 sunptr = &suptr->un_ent[0]; 441 for (i = 0; i < suptr->un_cnt; i++, sunptr++) { 442 if (sunptr->un_id != semid || sunptr->un_num != semnum) 443 continue; 444 sunptr->un_adjval += adjval; 445 if (sunptr->un_adjval == 0) { 446 suptr->un_cnt--; 447 if (i < suptr->un_cnt) 448 suptr->un_ent[i] = 449 suptr->un_ent[suptr->un_cnt]; 450 } 451 return (0); 452 } 453 454 /* Didn't find the right entry - create it */ 455 if (suptr->un_cnt == SEMUME) 456 return (EINVAL); 457 458 sunptr = &suptr->un_ent[suptr->un_cnt]; 459 suptr->un_cnt++; 460 sunptr->un_adjval = adjval; 461 sunptr->un_id = semid; 462 sunptr->un_num = semnum; 463 return (0); 464} 465 466void 467semundo_clear(int semid, int semnum) 468{ 469 struct sem_undo *suptr; 470 struct sem_undo_entry *sunptr, *sunend; 471 472 KASSERT(mutex_owned(&semlock)); 473 474 for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) 475 for (sunptr = &suptr->un_ent[0], 476 sunend = sunptr + suptr->un_cnt; sunptr < sunend;) { 477 if (sunptr->un_id == semid) { 478 if (semnum == -1 || sunptr->un_num == semnum) { 479 suptr->un_cnt--; 480 sunend--; 481 if (sunptr != sunend) 482 *sunptr = *sunend; 483 if (semnum != -1) 484 break; 485 else 486 continue; 487 } 488 } 489 sunptr++; 490 } 491} 492 493int 494sys_____semctl50(struct lwp *l, const struct sys_____semctl50_args *uap, 495 register_t *retval) 496{ 497 /* { 498 syscallarg(int) semid; 499 syscallarg(int) semnum; 500 syscallarg(int) cmd; 501 syscallarg(union __semun *) arg; 502 } */ 503 struct semid_ds sembuf; 504 int cmd, error; 505 void *pass_arg; 506 union __semun karg; 507 508 RUN_ONCE(&exithook_control, seminit_exithook); 509 510 cmd = SCARG(uap, cmd); 511 512 pass_arg = get_semctl_arg(cmd, &sembuf, &karg); 513 514 if (pass_arg) { 515 error = copyin(SCARG(uap, arg), &karg, sizeof(karg)); 516 if (error) 517 return error; 518 if (cmd == IPC_SET) { 519 error = copyin(karg.buf, &sembuf, sizeof(sembuf)); 520 if (error) 521 return (error); 522 } 523 } 524 525 error = semctl1(l, SCARG(uap, semid), SCARG(uap, semnum), cmd, 526 pass_arg, retval); 527 528 if (error == 0 && cmd == IPC_STAT) 529 error = copyout(&sembuf, karg.buf, sizeof(sembuf)); 530 531 return (error); 532} 533 534int 535semctl1(struct lwp *l, int semid, int semnum, int cmd, void *v, 536 register_t *retval) 537{ 538 kauth_cred_t cred = l->l_cred; 539 union __semun *arg = v; 540 struct semid_ds *sembuf = v, *semaptr; 541 int i, error, ix; 542 543 SEM_PRINTF(("call to semctl(%d, %d, %d, %p)\n", 544 semid, semnum, cmd, v)); 545 546 mutex_enter(&semlock); 547 548 ix = IPCID_TO_IX(semid); 549 if (ix < 0 || ix >= seminfo.semmni) { 550 mutex_exit(&semlock); 551 return (EINVAL); 552 } 553 554 semaptr = &sema[ix]; 555 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 556 semaptr->sem_perm._seq != IPCID_TO_SEQ(semid)) { 557 mutex_exit(&semlock); 558 return (EINVAL); 559 } 560 561 switch (cmd) { 562 case IPC_RMID: 563 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_M)) != 0) 564 break; 565 semaptr->sem_perm.cuid = kauth_cred_geteuid(cred); 566 semaptr->sem_perm.uid = kauth_cred_geteuid(cred); 567 semtot -= semaptr->sem_nsems; 568 for (i = semaptr->_sem_base - sem; i < semtot; i++) 569 sem[i] = sem[i + semaptr->sem_nsems]; 570 for (i = 0; i < seminfo.semmni; i++) { 571 if ((sema[i].sem_perm.mode & SEM_ALLOC) && 572 sema[i]._sem_base > semaptr->_sem_base) 573 sema[i]._sem_base -= semaptr->sem_nsems; 574 } 575 semaptr->sem_perm.mode = 0; 576 semundo_clear(ix, -1); 577 cv_broadcast(&semcv[ix]); 578 break; 579 580 case IPC_SET: 581 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_M))) 582 break; 583 KASSERT(sembuf != NULL); 584 semaptr->sem_perm.uid = sembuf->sem_perm.uid; 585 semaptr->sem_perm.gid = sembuf->sem_perm.gid; 586 semaptr->sem_perm.mode = (semaptr->sem_perm.mode & ~0777) | 587 (sembuf->sem_perm.mode & 0777); 588 semaptr->sem_ctime = time_second; 589 break; 590 591 case IPC_STAT: 592 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 593 break; 594 KASSERT(sembuf != NULL); 595 memset(sembuf, 0, sizeof *sembuf); 596 sembuf->sem_perm = semaptr->sem_perm; 597 sembuf->sem_perm.mode &= 0777; 598 sembuf->sem_nsems = semaptr->sem_nsems; 599 sembuf->sem_otime = semaptr->sem_otime; 600 sembuf->sem_ctime = semaptr->sem_ctime; 601 break; 602 603 case GETNCNT: 604 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 605 break; 606 if (semnum < 0 || semnum >= semaptr->sem_nsems) { 607 error = EINVAL; 608 break; 609 } 610 *retval = semaptr->_sem_base[semnum].semncnt; 611 break; 612 613 case GETPID: 614 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 615 break; 616 if (semnum < 0 || semnum >= semaptr->sem_nsems) { 617 error = EINVAL; 618 break; 619 } 620 *retval = semaptr->_sem_base[semnum].sempid; 621 break; 622 623 case GETVAL: 624 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 625 break; 626 if (semnum < 0 || semnum >= semaptr->sem_nsems) { 627 error = EINVAL; 628 break; 629 } 630 *retval = semaptr->_sem_base[semnum].semval; 631 break; 632 633 case GETALL: 634 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 635 break; 636 KASSERT(arg != NULL); 637 for (i = 0; i < semaptr->sem_nsems; i++) { 638 error = copyout(&semaptr->_sem_base[i].semval, 639 &arg->array[i], sizeof(arg->array[i])); 640 if (error != 0) 641 break; 642 } 643 break; 644 645 case GETZCNT: 646 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 647 break; 648 if (semnum < 0 || semnum >= semaptr->sem_nsems) { 649 error = EINVAL; 650 break; 651 } 652 *retval = semaptr->_sem_base[semnum].semzcnt; 653 break; 654 655 case SETVAL: 656 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W))) 657 break; 658 if (semnum < 0 || semnum >= semaptr->sem_nsems) { 659 error = EINVAL; 660 break; 661 } 662 KASSERT(arg != NULL); 663 if ((unsigned int)arg->val > seminfo.semvmx) { 664 error = ERANGE; 665 break; 666 } 667 semaptr->_sem_base[semnum].semval = arg->val; 668 semundo_clear(ix, semnum); 669 cv_broadcast(&semcv[ix]); 670 break; 671 672 case SETALL: 673 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W))) 674 break; 675 KASSERT(arg != NULL); 676 for (i = 0; i < semaptr->sem_nsems; i++) { 677 unsigned short semval; 678 error = copyin(&arg->array[i], &semval, 679 sizeof(arg->array[i])); 680 if (error != 0) 681 break; 682 if ((unsigned int)semval > seminfo.semvmx) { 683 error = ERANGE; 684 break; 685 } 686 semaptr->_sem_base[i].semval = semval; 687 } 688 semundo_clear(ix, -1); 689 cv_broadcast(&semcv[ix]); 690 break; 691 692 default: 693 error = EINVAL; 694 break; 695 } 696 697 mutex_exit(&semlock); 698 return (error); 699} 700 701int 702sys_semget(struct lwp *l, const struct sys_semget_args *uap, register_t *retval) 703{ 704 /* { 705 syscallarg(key_t) key; 706 syscallarg(int) nsems; 707 syscallarg(int) semflg; 708 } */ 709 int semid, error = 0; 710 int key = SCARG(uap, key); 711 int nsems = SCARG(uap, nsems); 712 int semflg = SCARG(uap, semflg); 713 kauth_cred_t cred = l->l_cred; 714 715 RUN_ONCE(&exithook_control, seminit_exithook); 716 717 SEM_PRINTF(("semget(0x%x, %d, 0%o)\n", key, nsems, semflg)); 718 719 mutex_enter(&semlock); 720 721 if (key != IPC_PRIVATE) { 722 for (semid = 0; semid < seminfo.semmni; semid++) { 723 if ((sema[semid].sem_perm.mode & SEM_ALLOC) && 724 sema[semid].sem_perm._key == key) 725 break; 726 } 727 if (semid < seminfo.semmni) { 728 SEM_PRINTF(("found public key\n")); 729 if ((error = ipcperm(cred, &sema[semid].sem_perm, 730 semflg & 0700))) 731 goto out; 732 if (nsems > 0 && sema[semid].sem_nsems < nsems) { 733 SEM_PRINTF(("too small\n")); 734 error = EINVAL; 735 goto out; 736 } 737 if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) { 738 SEM_PRINTF(("not exclusive\n")); 739 error = EEXIST; 740 goto out; 741 } 742 goto found; 743 } 744 } 745 746 SEM_PRINTF(("need to allocate the semid_ds\n")); 747 if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) { 748 if (nsems <= 0 || nsems > seminfo.semmsl) { 749 SEM_PRINTF(("nsems out of range (0<%d<=%d)\n", nsems, 750 seminfo.semmsl)); 751 error = EINVAL; 752 goto out; 753 } 754 if (nsems > seminfo.semmns - semtot) { 755 SEM_PRINTF(("not enough semaphores left " 756 "(need %d, got %d)\n", 757 nsems, seminfo.semmns - semtot)); 758 error = ENOSPC; 759 goto out; 760 } 761 for (semid = 0; semid < seminfo.semmni; semid++) { 762 if ((sema[semid].sem_perm.mode & SEM_ALLOC) == 0) 763 break; 764 } 765 if (semid == seminfo.semmni) { 766 SEM_PRINTF(("no more semid_ds's available\n")); 767 error = ENOSPC; 768 goto out; 769 } 770 SEM_PRINTF(("semid %d is available\n", semid)); 771 sema[semid].sem_perm._key = key; 772 sema[semid].sem_perm.cuid = kauth_cred_geteuid(cred); 773 sema[semid].sem_perm.uid = kauth_cred_geteuid(cred); 774 sema[semid].sem_perm.cgid = kauth_cred_getegid(cred); 775 sema[semid].sem_perm.gid = kauth_cred_getegid(cred); 776 sema[semid].sem_perm.mode = (semflg & 0777) | SEM_ALLOC; 777 sema[semid].sem_perm._seq = 778 (sema[semid].sem_perm._seq + 1) & 0x7fff; 779 sema[semid].sem_nsems = nsems; 780 sema[semid].sem_otime = 0; 781 sema[semid].sem_ctime = time_second; 782 sema[semid]._sem_base = &sem[semtot]; 783 semtot += nsems; 784 memset(sema[semid]._sem_base, 0, 785 sizeof(sema[semid]._sem_base[0]) * nsems); 786 SEM_PRINTF(("sembase = %p, next = %p\n", sema[semid]._sem_base, 787 &sem[semtot])); 788 } else { 789 SEM_PRINTF(("didn't find it and wasn't asked to create it\n")); 790 error = ENOENT; 791 goto out; 792 } 793 794 found: 795 *retval = IXSEQ_TO_IPCID(semid, sema[semid].sem_perm); 796 out: 797 mutex_exit(&semlock); 798 return (error); 799} 800 801#define SMALL_SOPS 8 802 803int 804sys_semop(struct lwp *l, const struct sys_semop_args *uap, register_t *retval) 805{ 806 /* { 807 syscallarg(int) semid; 808 syscallarg(struct sembuf *) sops; 809 syscallarg(size_t) nsops; 810 } */ 811 struct proc *p = l->l_proc; 812 int semid = SCARG(uap, semid), seq; 813 size_t nsops = SCARG(uap, nsops); 814 struct sembuf small_sops[SMALL_SOPS]; 815 struct sembuf *sops; 816 struct semid_ds *semaptr; 817 struct sembuf *sopptr = NULL; 818 struct __sem *semptr = NULL; 819 struct sem_undo *suptr = NULL; 820 kauth_cred_t cred = l->l_cred; 821 int i, error; 822 int do_wakeup, do_undos; 823 824 RUN_ONCE(&exithook_control, seminit_exithook); 825 826 SEM_PRINTF(("call to semop(%d, %p, %zd)\n", semid, SCARG(uap,sops), nsops)); 827 828 if (__predict_false((p->p_flag & PK_SYSVSEM) == 0)) { 829 mutex_enter(p->p_lock); 830 p->p_flag |= PK_SYSVSEM; 831 mutex_exit(p->p_lock); 832 } 833 834restart: 835 if (nsops <= SMALL_SOPS) { 836 sops = small_sops; 837 } else if (nsops <= seminfo.semopm) { 838 sops = kmem_alloc(nsops * sizeof(*sops), KM_SLEEP); 839 } else { 840 SEM_PRINTF(("too many sops (max=%d, nsops=%zd)\n", 841 seminfo.semopm, nsops)); 842 return (E2BIG); 843 } 844 845 error = copyin(SCARG(uap, sops), sops, nsops * sizeof(sops[0])); 846 if (error) { 847 SEM_PRINTF(("error = %d from copyin(%p, %p, %zd)\n", error, 848 SCARG(uap, sops), &sops, nsops * sizeof(sops[0]))); 849 if (sops != small_sops) 850 kmem_free(sops, nsops * sizeof(*sops)); 851 return error; 852 } 853 854 mutex_enter(&semlock); 855 /* In case of reallocation, we will wait for completion */ 856 while (__predict_false(sem_realloc_state)) 857 cv_wait(&sem_realloc_cv, &semlock); 858 859 semid = IPCID_TO_IX(semid); /* Convert back to zero origin */ 860 if (semid < 0 || semid >= seminfo.semmni) { 861 error = EINVAL; 862 goto out; 863 } 864 865 semaptr = &sema[semid]; 866 seq = IPCID_TO_SEQ(SCARG(uap, semid)); 867 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 868 semaptr->sem_perm._seq != seq) { 869 error = EINVAL; 870 goto out; 871 } 872 873 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W))) { 874 SEM_PRINTF(("error = %d from ipaccess\n", error)); 875 goto out; 876 } 877 878 for (i = 0; i < nsops; i++) 879 if (sops[i].sem_num >= semaptr->sem_nsems) { 880 error = EFBIG; 881 goto out; 882 } 883 884 /* 885 * Loop trying to satisfy the vector of requests. 886 * If we reach a point where we must wait, any requests already 887 * performed are rolled back and we go to sleep until some other 888 * process wakes us up. At this point, we start all over again. 889 * 890 * This ensures that from the perspective of other tasks, a set 891 * of requests is atomic (never partially satisfied). 892 */ 893 do_undos = 0; 894 895 for (;;) { 896 do_wakeup = 0; 897 898 for (i = 0; i < nsops; i++) { 899 sopptr = &sops[i]; 900 semptr = &semaptr->_sem_base[sopptr->sem_num]; 901 902 SEM_PRINTF(("semop: semaptr=%p, sem_base=%p, " 903 "semptr=%p, sem[%d]=%d : op=%d, flag=%s\n", 904 semaptr, semaptr->_sem_base, semptr, 905 sopptr->sem_num, semptr->semval, sopptr->sem_op, 906 (sopptr->sem_flg & IPC_NOWAIT) ? 907 "nowait" : "wait")); 908 909 if (sopptr->sem_op < 0) { 910 if ((int)(semptr->semval + 911 sopptr->sem_op) < 0) { 912 SEM_PRINTF(("semop: " 913 "can't do it now\n")); 914 break; 915 } else { 916 semptr->semval += sopptr->sem_op; 917 if (semptr->semval == 0 && 918 semptr->semzcnt > 0) 919 do_wakeup = 1; 920 } 921 if (sopptr->sem_flg & SEM_UNDO) 922 do_undos = 1; 923 } else if (sopptr->sem_op == 0) { 924 if (semptr->semval > 0) { 925 SEM_PRINTF(("semop: not zero now\n")); 926 break; 927 } 928 } else { 929 if (semptr->semncnt > 0) 930 do_wakeup = 1; 931 semptr->semval += sopptr->sem_op; 932 if (sopptr->sem_flg & SEM_UNDO) 933 do_undos = 1; 934 } 935 } 936 937 /* 938 * Did we get through the entire vector? 939 */ 940 if (i >= nsops) 941 goto done; 942 943 /* 944 * No ... rollback anything that we've already done 945 */ 946 SEM_PRINTF(("semop: rollback 0 through %d\n", i - 1)); 947 while (i-- > 0) 948 semaptr->_sem_base[sops[i].sem_num].semval -= 949 sops[i].sem_op; 950 951 /* 952 * If the request that we couldn't satisfy has the 953 * NOWAIT flag set then return with EAGAIN. 954 */ 955 if (sopptr->sem_flg & IPC_NOWAIT) { 956 error = EAGAIN; 957 goto out; 958 } 959 960 if (sopptr->sem_op == 0) 961 semptr->semzcnt++; 962 else 963 semptr->semncnt++; 964 965 sem_waiters++; 966 SEM_PRINTF(("semop: good night!\n")); 967 error = cv_wait_sig(&semcv[semid], &semlock); 968 SEM_PRINTF(("semop: good morning (error=%d)!\n", error)); 969 sem_waiters--; 970 971 /* Notify reallocator, if it is waiting */ 972 cv_broadcast(&sem_realloc_cv); 973 974 /* 975 * Make sure that the semaphore still exists 976 */ 977 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 978 semaptr->sem_perm._seq != seq) { 979 error = EIDRM; 980 goto out; 981 } 982 983 /* 984 * The semaphore is still alive. Readjust the count of 985 * waiting processes. 986 */ 987 semptr = &semaptr->_sem_base[sopptr->sem_num]; 988 if (sopptr->sem_op == 0) 989 semptr->semzcnt--; 990 else 991 semptr->semncnt--; 992 993 /* In case of such state, restart the call */ 994 if (sem_realloc_state) { 995 mutex_exit(&semlock); 996 goto restart; 997 } 998 999 /* Is it really morning, or was our sleep interrupted? */ 1000 if (error != 0) { 1001 error = EINTR; 1002 goto out; 1003 } 1004 SEM_PRINTF(("semop: good morning!\n")); 1005 } 1006 1007done: 1008 /* 1009 * Process any SEM_UNDO requests. 1010 */ 1011 if (do_undos) { 1012 for (i = 0; i < nsops; i++) { 1013 /* 1014 * We only need to deal with SEM_UNDO's for non-zero 1015 * op's. 1016 */ 1017 int adjval; 1018 1019 if ((sops[i].sem_flg & SEM_UNDO) == 0) 1020 continue; 1021 adjval = sops[i].sem_op; 1022 if (adjval == 0) 1023 continue; 1024 error = semundo_adjust(p, &suptr, semid, 1025 sops[i].sem_num, -adjval); 1026 if (error == 0) 1027 continue; 1028 1029 /* 1030 * Oh-Oh! We ran out of either sem_undo's or undo's. 1031 * Rollback the adjustments to this point and then 1032 * rollback the semaphore ups and down so we can return 1033 * with an error with all structures restored. We 1034 * rollback the undo's in the exact reverse order that 1035 * we applied them. This guarantees that we won't run 1036 * out of space as we roll things back out. 1037 */ 1038 while (i-- > 0) { 1039 if ((sops[i].sem_flg & SEM_UNDO) == 0) 1040 continue; 1041 adjval = sops[i].sem_op; 1042 if (adjval == 0) 1043 continue; 1044 if (semundo_adjust(p, &suptr, semid, 1045 sops[i].sem_num, adjval) != 0) 1046 panic("semop - can't undo undos"); 1047 } 1048 1049 for (i = 0; i < nsops; i++) 1050 semaptr->_sem_base[sops[i].sem_num].semval -= 1051 sops[i].sem_op; 1052 1053 SEM_PRINTF(("error = %d from semundo_adjust\n", error)); 1054 goto out; 1055 } /* loop through the sops */ 1056 } /* if (do_undos) */ 1057 1058 /* We're definitely done - set the sempid's */ 1059 for (i = 0; i < nsops; i++) { 1060 sopptr = &sops[i]; 1061 semptr = &semaptr->_sem_base[sopptr->sem_num]; 1062 semptr->sempid = p->p_pid; 1063 } 1064 1065 /* Update sem_otime */ 1066 semaptr->sem_otime = time_second; 1067 1068 /* Do a wakeup if any semaphore was up'd. */ 1069 if (do_wakeup) { 1070 SEM_PRINTF(("semop: doing wakeup\n")); 1071 cv_broadcast(&semcv[semid]); 1072 SEM_PRINTF(("semop: back from wakeup\n")); 1073 } 1074 SEM_PRINTF(("semop: done\n")); 1075 *retval = 0; 1076 1077 out: 1078 mutex_exit(&semlock); 1079 if (sops != small_sops) 1080 kmem_free(sops, nsops * sizeof(*sops)); 1081 return error; 1082} 1083 1084/* 1085 * Go through the undo structures for this process and apply the 1086 * adjustments to semaphores. 1087 */ 1088/*ARGSUSED*/ 1089void 1090semexit(struct proc *p, void *v) 1091{ 1092 struct sem_undo *suptr; 1093 struct sem_undo **supptr; 1094 1095 if ((p->p_flag & PK_SYSVSEM) == 0) 1096 return; 1097 1098 mutex_enter(&semlock); 1099 1100 /* 1101 * Go through the chain of undo vectors looking for one 1102 * associated with this process. 1103 */ 1104 1105 for (supptr = &semu_list; (suptr = *supptr) != NULL; 1106 supptr = &suptr->un_next) { 1107 if (suptr->un_proc == p) 1108 break; 1109 } 1110 1111 /* 1112 * If there is no undo vector, skip to the end. 1113 */ 1114 1115 if (suptr == NULL) { 1116 mutex_exit(&semlock); 1117 return; 1118 } 1119 1120 /* 1121 * We now have an undo vector for this process. 1122 */ 1123 1124 SEM_PRINTF(("proc @%p has undo structure with %d entries\n", p, 1125 suptr->un_cnt)); 1126 1127 /* 1128 * If there are any active undo elements then process them. 1129 */ 1130 if (suptr->un_cnt > 0) { 1131 int ix; 1132 1133 for (ix = 0; ix < suptr->un_cnt; ix++) { 1134 int semid = suptr->un_ent[ix].un_id; 1135 int semnum = suptr->un_ent[ix].un_num; 1136 int adjval = suptr->un_ent[ix].un_adjval; 1137 struct semid_ds *semaptr; 1138 1139 semaptr = &sema[semid]; 1140 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) 1141 if (semnum >= semaptr->sem_nsems) 1142 panic("semexit - semnum out of range"); 1143 1144 SEM_PRINTF(("semexit: %p id=%d num=%d(adj=%d) ; " 1145 "sem=%d\n", 1146 suptr->un_proc, suptr->un_ent[ix].un_id, 1147 suptr->un_ent[ix].un_num, 1148 suptr->un_ent[ix].un_adjval, 1149 semaptr->_sem_base[semnum].semval)); 1150 1151 if (adjval < 0 && 1152 semaptr->_sem_base[semnum].semval < -adjval) 1153 semaptr->_sem_base[semnum].semval = 0; 1154 else 1155 semaptr->_sem_base[semnum].semval += adjval; 1156 1157 cv_broadcast(&semcv[semid]); 1158 SEM_PRINTF(("semexit: back from wakeup\n")); 1159 } 1160 } 1161 1162 /* 1163 * Deallocate the undo vector. 1164 */ 1165 SEM_PRINTF(("removing vector\n")); 1166 suptr->un_proc = NULL; 1167 *supptr = suptr->un_next; 1168 mutex_exit(&semlock); 1169} 1170 1171/* 1172 * Sysctl initialization and nodes. 1173 */ 1174 1175static int 1176sysctl_ipc_semmni(SYSCTLFN_ARGS) 1177{ 1178 int newsize, error; 1179 struct sysctlnode node; 1180 node = *rnode; 1181 node.sysctl_data = &newsize; 1182 1183 newsize = seminfo.semmni; 1184 error = sysctl_lookup(SYSCTLFN_CALL(&node)); 1185 if (error || newp == NULL) 1186 return error; 1187 1188 return semrealloc(newsize, seminfo.semmns, seminfo.semmnu); 1189} 1190 1191static int 1192sysctl_ipc_semmns(SYSCTLFN_ARGS) 1193{ 1194 int newsize, error; 1195 struct sysctlnode node; 1196 node = *rnode; 1197 node.sysctl_data = &newsize; 1198 1199 newsize = seminfo.semmns; 1200 error = sysctl_lookup(SYSCTLFN_CALL(&node)); 1201 if (error || newp == NULL) 1202 return error; 1203 1204 return semrealloc(seminfo.semmni, newsize, seminfo.semmnu); 1205} 1206 1207static int 1208sysctl_ipc_semmnu(SYSCTLFN_ARGS) 1209{ 1210 int newsize, error; 1211 struct sysctlnode node; 1212 node = *rnode; 1213 node.sysctl_data = &newsize; 1214 1215 newsize = seminfo.semmnu; 1216 error = sysctl_lookup(SYSCTLFN_CALL(&node)); 1217 if (error || newp == NULL) 1218 return error; 1219 1220 return semrealloc(seminfo.semmni, seminfo.semmns, newsize); 1221} 1222 1223SYSCTL_SETUP(sysctl_ipc_sem_setup, "sysctl kern.ipc subtree setup") 1224{ 1225 const struct sysctlnode *node = NULL; 1226 1227 sysctl_createv(clog, 0, NULL, &node, 1228 CTLFLAG_PERMANENT, 1229 CTLTYPE_NODE, "ipc", 1230 SYSCTL_DESCR("SysV IPC options"), 1231 NULL, 0, NULL, 0, 1232 CTL_KERN, KERN_SYSVIPC, CTL_EOL); 1233 1234 if (node == NULL) 1235 return; 1236 1237 sysctl_createv(clog, 0, &node, NULL, 1238 CTLFLAG_PERMANENT | CTLFLAG_READWRITE, 1239 CTLTYPE_INT, "semmni", 1240 SYSCTL_DESCR("Max number of number of semaphore identifiers"), 1241 sysctl_ipc_semmni, 0, &seminfo.semmni, 0, 1242 CTL_CREATE, CTL_EOL); 1243 sysctl_createv(clog, 0, &node, NULL, 1244 CTLFLAG_PERMANENT | CTLFLAG_READWRITE, 1245 CTLTYPE_INT, "semmns", 1246 SYSCTL_DESCR("Max number of number of semaphores in system"), 1247 sysctl_ipc_semmns, 0, &seminfo.semmns, 0, 1248 CTL_CREATE, CTL_EOL); 1249 sysctl_createv(clog, 0, &node, NULL, 1250 CTLFLAG_PERMANENT | CTLFLAG_READWRITE, 1251 CTLTYPE_INT, "semmnu", 1252 SYSCTL_DESCR("Max number of undo structures in system"), 1253 sysctl_ipc_semmnu, 0, &seminfo.semmnu, 0, 1254 CTL_CREATE, CTL_EOL); 1255} 1256