1 /* $NetBSD: sysv_sem.c,v 1.101 2024/10/06 22:15:33 mlelstv 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 1.101 2024/10/06 22:15:33 mlelstv 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 */ 65 struct semid_ds * sema __read_mostly; 66 static struct __sem * sem __read_mostly; 67 static kcondvar_t * semcv __read_mostly; 68 static int * semu __read_mostly; 69 70 static kmutex_t semlock __cacheline_aligned; 71 static bool sem_realloc_state __read_mostly; 72 static 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 */ 78 static struct sem_undo *semu_list __read_mostly; 79 static u_int semtot __cacheline_aligned; 80 static 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 91 void *hook; /* cookie from exithook_establish() */ 92 93 extern int kern_has_sysvsem; 94 95 SYSCTL_SETUP_PROTO(sysctl_ipc_sem_setup); 96 97 struct sem_undo *semu_alloc(struct proc *); 98 int semundo_adjust(struct proc *, struct sem_undo **, int, int, int); 99 void semundo_clear(int, int); 100 101 static ONCE_DECL(exithook_control); 102 static int seminit_exithook(void); 103 104 int 105 seminit(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 } 150 151 static int 152 seminit_exithook(void) 153 { 154 155 hook = exithook_establish(semexit, NULL); 156 return 0; 157 } 158 159 int 160 semfini(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 } 198 199 static int 200 semrealloc(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 */ 344 345 int 346 sys_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 */ 359 struct sem_undo * 360 semu_alloc(struct proc *p) 361 { 362 struct sem_undo *suptr, **supptr; 363 bool attempted = false; 364 int i; 365 366 KASSERT(mutex_owned(&semlock)); 367 again: 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 */ 406 407 int 408 semundo_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 } 465 466 void 467 semundo_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 } 492 493 int 494 sys_____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 } 533 534 int 535 semctl1(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 } 700 701 int 702 sys_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 8 802 803 static int 804 do_semop(struct lwp *l, int usemid, struct sembuf *usops, 805 size_t nsops, struct timespec *utimeout, register_t *retval) 806 { 807 struct proc *p = l->l_proc; 808 int semid, seq; 809 struct sembuf small_sops[SMALL_SOPS]; 810 struct sembuf *sops; 811 struct semid_ds *semaptr; 812 struct sembuf *sopptr = NULL; 813 struct __sem *semptr = NULL; 814 struct sem_undo *suptr = NULL; 815 kauth_cred_t cred = l->l_cred; 816 struct timespec timeout; 817 int timo = 0; 818 int i, error; 819 int do_wakeup, do_undos; 820 821 RUN_ONCE(&exithook_control, seminit_exithook); 822 823 SEM_PRINTF(("call to semop(%d, %p, %zu)\n", usemid, usops, nsops)); 824 825 if (__predict_false((p->p_flag & PK_SYSVSEM) == 0)) { 826 mutex_enter(p->p_lock); 827 p->p_flag |= PK_SYSVSEM; 828 mutex_exit(p->p_lock); 829 } 830 831 restart: 832 if (nsops <= SMALL_SOPS) { 833 sops = small_sops; 834 } else if (nsops <= seminfo.semopm) { 835 sops = kmem_alloc(nsops * sizeof(*sops), KM_SLEEP); 836 } else { 837 SEM_PRINTF(("too many sops (max=%d, nsops=%zu)\n", 838 seminfo.semopm, nsops)); 839 return (E2BIG); 840 } 841 842 error = copyin(usops, sops, nsops * sizeof(sops[0])); 843 if (error) { 844 SEM_PRINTF(("error = %d from copyin(%p, %p, %zu)\n", error, 845 usops, &sops, nsops * sizeof(sops[0]))); 846 if (sops != small_sops) 847 kmem_free(sops, nsops * sizeof(*sops)); 848 return error; 849 } 850 851 mutex_enter(&semlock); 852 /* In case of reallocation, we will wait for completion */ 853 while (__predict_false(sem_realloc_state)) 854 cv_wait(&sem_realloc_cv, &semlock); 855 856 semid = IPCID_TO_IX(usemid); /* Convert back to zero origin */ 857 if (semid < 0 || semid >= seminfo.semmni) { 858 error = EINVAL; 859 goto out; 860 } 861 862 if (utimeout) { 863 error = copyin(utimeout, &timeout, sizeof(timeout)); 864 if (error) { 865 SEM_PRINTF(("error = %d from copyin(%p, %p, %zu)\n", 866 error, utimeout, &timeout, sizeof(timeout))); 867 return error; 868 } 869 error = ts2timo(CLOCK_MONOTONIC, TIMER_RELTIME, &timeout, 870 &timo, NULL); 871 if (error) 872 return error; 873 } 874 875 semaptr = &sema[semid]; 876 seq = IPCID_TO_SEQ(usemid); 877 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 878 semaptr->sem_perm._seq != seq) { 879 error = EINVAL; 880 goto out; 881 } 882 883 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W))) { 884 SEM_PRINTF(("error = %d from ipaccess\n", error)); 885 goto out; 886 } 887 888 for (i = 0; i < nsops; i++) 889 if (sops[i].sem_num >= semaptr->sem_nsems) { 890 error = EFBIG; 891 goto out; 892 } 893 /* 894 * Loop trying to satisfy the vector of requests. 895 * If we reach a point where we must wait, any requests already 896 * performed are rolled back and we go to sleep until some other 897 * process wakes us up. At this point, we start all over again. 898 * 899 * This ensures that from the perspective of other tasks, a set 900 * of requests is atomic (never partially satisfied). 901 */ 902 do_undos = 0; 903 904 for (;;) { 905 do_wakeup = 0; 906 907 for (i = 0; i < nsops; i++) { 908 sopptr = &sops[i]; 909 semptr = &semaptr->_sem_base[sopptr->sem_num]; 910 911 SEM_PRINTF(("semop: semaptr=%p, sem_base=%p, " 912 "semptr=%p, sem[%d]=%d : op=%d, flag=%s\n", 913 semaptr, semaptr->_sem_base, semptr, 914 sopptr->sem_num, semptr->semval, sopptr->sem_op, 915 (sopptr->sem_flg & IPC_NOWAIT) ? 916 "nowait" : "wait")); 917 918 if (sopptr->sem_op < 0) { 919 if ((int)(semptr->semval + 920 sopptr->sem_op) < 0) { 921 SEM_PRINTF(("semop: " 922 "can't do it now\n")); 923 break; 924 } else { 925 semptr->semval += sopptr->sem_op; 926 if (semptr->semval == 0 && 927 semptr->semzcnt > 0) 928 do_wakeup = 1; 929 } 930 if (sopptr->sem_flg & SEM_UNDO) 931 do_undos = 1; 932 } else if (sopptr->sem_op == 0) { 933 if (semptr->semval > 0) { 934 SEM_PRINTF(("semop: not zero now\n")); 935 break; 936 } 937 } else { 938 if (semptr->semncnt > 0) 939 do_wakeup = 1; 940 semptr->semval += sopptr->sem_op; 941 if (sopptr->sem_flg & SEM_UNDO) 942 do_undos = 1; 943 } 944 } 945 946 /* 947 * Did we get through the entire vector? 948 */ 949 if (i >= nsops) 950 goto done; 951 952 /* 953 * No ... rollback anything that we've already done 954 */ 955 SEM_PRINTF(("semop: rollback 0 through %d\n", i - 1)); 956 while (i-- > 0) 957 semaptr->_sem_base[sops[i].sem_num].semval -= 958 sops[i].sem_op; 959 960 /* 961 * If the request that we couldn't satisfy has the 962 * NOWAIT flag set then return with EAGAIN. 963 */ 964 if (sopptr->sem_flg & IPC_NOWAIT) { 965 error = EAGAIN; 966 goto out; 967 } 968 969 if (sopptr->sem_op == 0) 970 semptr->semzcnt++; 971 else 972 semptr->semncnt++; 973 974 sem_waiters++; 975 SEM_PRINTF(("semop: good night!\n")); 976 error = cv_timedwait_sig(&semcv[semid], &semlock, timo); 977 SEM_PRINTF(("semop: good morning (error=%d)!\n", error)); 978 sem_waiters--; 979 980 /* Notify reallocator, if it is waiting */ 981 cv_broadcast(&sem_realloc_cv); 982 983 /* 984 * Make sure that the semaphore still exists 985 */ 986 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 987 semaptr->sem_perm._seq != seq) { 988 error = EIDRM; 989 goto out; 990 } 991 992 /* 993 * The semaphore is still alive. Readjust the count of 994 * waiting processes. 995 */ 996 semptr = &semaptr->_sem_base[sopptr->sem_num]; 997 if (sopptr->sem_op == 0) 998 semptr->semzcnt--; 999 else 1000 semptr->semncnt--; 1001 1002 /* In case of such state, restart the call */ 1003 if (sem_realloc_state) { 1004 mutex_exit(&semlock); 1005 goto restart; 1006 } 1007 1008 /* Is it really morning, or was our sleep interrupted? */ 1009 if (error != 0) { 1010 if (error == ERESTART) 1011 error = EINTR; // Simplify to just EINTR 1012 else if (error == EWOULDBLOCK) 1013 error = EAGAIN; // Convert timeout to EAGAIN 1014 goto out; 1015 } 1016 SEM_PRINTF(("semop: good morning!\n")); 1017 } 1018 done: 1019 /* 1020 * Process any SEM_UNDO requests. 1021 */ 1022 if (do_undos) { 1023 for (i = 0; i < nsops; i++) { 1024 /* 1025 * We only need to deal with SEM_UNDO's for non-zero 1026 * op's. 1027 */ 1028 int adjval; 1029 1030 if ((sops[i].sem_flg & SEM_UNDO) == 0) 1031 continue; 1032 adjval = sops[i].sem_op; 1033 if (adjval == 0) 1034 continue; 1035 error = semundo_adjust(p, &suptr, semid, 1036 sops[i].sem_num, -adjval); 1037 if (error == 0) 1038 continue; 1039 1040 /* 1041 * Oh-Oh! We ran out of either sem_undo's or undo's. 1042 * Rollback the adjustments to this point and then 1043 * rollback the semaphore ups and down so we can return 1044 * with an error with all structures restored. We 1045 * rollback the undo's in the exact reverse order that 1046 * we applied them. This guarantees that we won't run 1047 * out of space as we roll things back out. 1048 */ 1049 while (i-- > 0) { 1050 if ((sops[i].sem_flg & SEM_UNDO) == 0) 1051 continue; 1052 adjval = sops[i].sem_op; 1053 if (adjval == 0) 1054 continue; 1055 if (semundo_adjust(p, &suptr, semid, 1056 sops[i].sem_num, adjval) != 0) 1057 panic("semop - can't undo undos"); 1058 } 1059 1060 for (i = 0; i < nsops; i++) 1061 semaptr->_sem_base[sops[i].sem_num].semval -= 1062 sops[i].sem_op; 1063 1064 SEM_PRINTF(("error = %d from semundo_adjust\n", error)); 1065 goto out; 1066 } /* loop through the sops */ 1067 } /* if (do_undos) */ 1068 1069 /* We're definitely done - set the sempid's */ 1070 for (i = 0; i < nsops; i++) { 1071 sopptr = &sops[i]; 1072 semptr = &semaptr->_sem_base[sopptr->sem_num]; 1073 semptr->sempid = p->p_pid; 1074 } 1075 1076 /* Update sem_otime */ 1077 semaptr->sem_otime = time_second; 1078 1079 /* Do a wakeup if any semaphore was up'd. */ 1080 if (do_wakeup) { 1081 SEM_PRINTF(("semop: doing wakeup\n")); 1082 cv_broadcast(&semcv[semid]); 1083 SEM_PRINTF(("semop: back from wakeup\n")); 1084 } 1085 SEM_PRINTF(("semop: done\n")); 1086 *retval = 0; 1087 1088 out: 1089 mutex_exit(&semlock); 1090 if (sops != small_sops) 1091 kmem_free(sops, nsops * sizeof(*sops)); 1092 return error; 1093 } 1094 1095 int 1096 sys_semtimedop(struct lwp *l, const struct sys_semtimedop_args *uap, 1097 register_t *retval) 1098 { 1099 /* { 1100 syscallarg(int) semid; 1101 syscallarg(struct sembuf *) sops; 1102 syscallarg(size_t) nsops; 1103 syscallarg(struct timespec) timeout; 1104 } */ 1105 int semid = SCARG(uap, semid); 1106 struct sembuf *sops = SCARG(uap, sops); 1107 size_t nsops = SCARG(uap, nsops); 1108 struct timespec *utimeout = SCARG(uap, timeout); 1109 1110 return do_semop(l, semid, sops, nsops, utimeout, retval); 1111 } 1112 1113 int 1114 sys_semop(struct lwp *l, const struct sys_semop_args *uap, register_t *retval) 1115 { 1116 /* { 1117 syscallarg(int) semid; 1118 syscallarg(struct sembuf *) sops; 1119 syscallarg(size_t) nsops; 1120 } */ 1121 int semid = SCARG(uap, semid); 1122 struct sembuf *sops = SCARG(uap, sops); 1123 size_t nsops = SCARG(uap, nsops); 1124 1125 return do_semop(l, semid, sops, nsops, NULL, retval); 1126 } 1127 1128 /* 1129 * Go through the undo structures for this process and apply the 1130 * adjustments to semaphores. 1131 */ 1132 /*ARGSUSED*/ 1133 void 1134 semexit(struct proc *p, void *v) 1135 { 1136 struct sem_undo *suptr; 1137 struct sem_undo **supptr; 1138 1139 if ((p->p_flag & PK_SYSVSEM) == 0) 1140 return; 1141 1142 mutex_enter(&semlock); 1143 1144 /* 1145 * Go through the chain of undo vectors looking for one 1146 * associated with this process. 1147 */ 1148 1149 for (supptr = &semu_list; (suptr = *supptr) != NULL; 1150 supptr = &suptr->un_next) { 1151 if (suptr->un_proc == p) 1152 break; 1153 } 1154 1155 /* 1156 * If there is no undo vector, skip to the end. 1157 */ 1158 1159 if (suptr == NULL) { 1160 mutex_exit(&semlock); 1161 return; 1162 } 1163 1164 /* 1165 * We now have an undo vector for this process. 1166 */ 1167 1168 SEM_PRINTF(("proc @%p has undo structure with %d entries\n", p, 1169 suptr->un_cnt)); 1170 1171 /* 1172 * If there are any active undo elements then process them. 1173 */ 1174 if (suptr->un_cnt > 0) { 1175 int ix; 1176 1177 for (ix = 0; ix < suptr->un_cnt; ix++) { 1178 int semid = suptr->un_ent[ix].un_id; 1179 int semnum = suptr->un_ent[ix].un_num; 1180 int adjval = suptr->un_ent[ix].un_adjval; 1181 struct semid_ds *semaptr; 1182 1183 semaptr = &sema[semid]; 1184 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) 1185 if (semnum >= semaptr->sem_nsems) 1186 panic("semexit - semnum out of range"); 1187 1188 SEM_PRINTF(("semexit: %p id=%d num=%d(adj=%d) ; " 1189 "sem=%d\n", 1190 suptr->un_proc, suptr->un_ent[ix].un_id, 1191 suptr->un_ent[ix].un_num, 1192 suptr->un_ent[ix].un_adjval, 1193 semaptr->_sem_base[semnum].semval)); 1194 1195 if (adjval < 0 && 1196 semaptr->_sem_base[semnum].semval < -adjval) 1197 semaptr->_sem_base[semnum].semval = 0; 1198 else 1199 semaptr->_sem_base[semnum].semval += adjval; 1200 1201 cv_broadcast(&semcv[semid]); 1202 SEM_PRINTF(("semexit: back from wakeup\n")); 1203 } 1204 } 1205 1206 /* 1207 * Deallocate the undo vector. 1208 */ 1209 SEM_PRINTF(("removing vector\n")); 1210 suptr->un_proc = NULL; 1211 *supptr = suptr->un_next; 1212 mutex_exit(&semlock); 1213 } 1214 1215 /* 1216 * Sysctl initialization and nodes. 1217 */ 1218 1219 static int 1220 sysctl_ipc_semmni(SYSCTLFN_ARGS) 1221 { 1222 int newsize, error; 1223 struct sysctlnode node; 1224 node = *rnode; 1225 node.sysctl_data = &newsize; 1226 1227 newsize = seminfo.semmni; 1228 error = sysctl_lookup(SYSCTLFN_CALL(&node)); 1229 if (error || newp == NULL) 1230 return error; 1231 1232 return semrealloc(newsize, seminfo.semmns, seminfo.semmnu); 1233 } 1234 1235 static int 1236 sysctl_ipc_semmns(SYSCTLFN_ARGS) 1237 { 1238 int newsize, error; 1239 struct sysctlnode node; 1240 node = *rnode; 1241 node.sysctl_data = &newsize; 1242 1243 newsize = seminfo.semmns; 1244 error = sysctl_lookup(SYSCTLFN_CALL(&node)); 1245 if (error || newp == NULL) 1246 return error; 1247 1248 return semrealloc(seminfo.semmni, newsize, seminfo.semmnu); 1249 } 1250 1251 static int 1252 sysctl_ipc_semmnu(SYSCTLFN_ARGS) 1253 { 1254 int newsize, error; 1255 struct sysctlnode node; 1256 node = *rnode; 1257 node.sysctl_data = &newsize; 1258 1259 newsize = seminfo.semmnu; 1260 error = sysctl_lookup(SYSCTLFN_CALL(&node)); 1261 if (error || newp == NULL) 1262 return error; 1263 1264 return semrealloc(seminfo.semmni, seminfo.semmns, newsize); 1265 } 1266 1267 SYSCTL_SETUP(sysctl_ipc_sem_setup, "sysctl kern.ipc subtree setup") 1268 { 1269 const struct sysctlnode *node = NULL; 1270 1271 sysctl_createv(clog, 0, NULL, &node, 1272 CTLFLAG_PERMANENT, 1273 CTLTYPE_NODE, "ipc", 1274 SYSCTL_DESCR("SysV IPC options"), 1275 NULL, 0, NULL, 0, 1276 CTL_KERN, KERN_SYSVIPC, CTL_EOL); 1277 1278 if (node == NULL) 1279 return; 1280 1281 sysctl_createv(clog, 0, &node, NULL, 1282 CTLFLAG_PERMANENT | CTLFLAG_READWRITE, 1283 CTLTYPE_INT, "semmni", 1284 SYSCTL_DESCR("Max number of number of semaphore identifiers"), 1285 sysctl_ipc_semmni, 0, &seminfo.semmni, 0, 1286 CTL_CREATE, CTL_EOL); 1287 sysctl_createv(clog, 0, &node, NULL, 1288 CTLFLAG_PERMANENT | CTLFLAG_READWRITE, 1289 CTLTYPE_INT, "semmns", 1290 SYSCTL_DESCR("Max number of number of semaphores in system"), 1291 sysctl_ipc_semmns, 0, &seminfo.semmns, 0, 1292 CTL_CREATE, CTL_EOL); 1293 sysctl_createv(clog, 0, &node, NULL, 1294 CTLFLAG_PERMANENT | CTLFLAG_READWRITE, 1295 CTLTYPE_INT, "semmnu", 1296 SYSCTL_DESCR("Max number of undo structures in system"), 1297 sysctl_ipc_semmnu, 0, &seminfo.semmnu, 0, 1298 CTL_CREATE, CTL_EOL); 1299 } 1300