Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_sem.c
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1 /*- 2 * Copyright (c) 2002 Alfred Perlstein <alfred@FreeBSD.org> 3 * Copyright (c) 2003-2005 SPARTA, Inc. 4 * Copyright (c) 2005 Robert N. M. Watson 5 * All rights reserved. 6 * 7 * This software was developed for the FreeBSD Project in part by Network 8 * Associates Laboratories, the Security Research Division of Network 9 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), 10 * as part of the DARPA CHATS research program. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #include <sys/cdefs.h> 35 __FBSDID("$FreeBSD: releng/8.4/sys/kern/uipc_sem.c 217845 2011-01-25 20:54:15Z jhb $"); 36 37 #include "opt_compat.h" 38 #include "opt_posix.h" 39 40 #include <sys/param.h> 41 #include <sys/condvar.h> 42 #include <sys/fcntl.h> 43 #include <sys/file.h> 44 #include <sys/filedesc.h> 45 #include <sys/fnv_hash.h> 46 #include <sys/kernel.h> 47 #include <sys/ksem.h> 48 #include <sys/lock.h> 49 #include <sys/malloc.h> 50 #include <sys/module.h> 51 #include <sys/mutex.h> 52 #include <sys/priv.h> 53 #include <sys/proc.h> 54 #include <sys/posix4.h> 55 #include <sys/semaphore.h> 56 #include <sys/_semaphore.h> 57 #include <sys/stat.h> 58 #include <sys/syscall.h> 59 #include <sys/syscallsubr.h> 60 #include <sys/sysctl.h> 61 #include <sys/sysent.h> 62 #include <sys/sysproto.h> 63 #include <sys/systm.h> 64 #include <sys/sx.h> 65 #include <sys/vnode.h> 66 67 #include <security/mac/mac_framework.h> 68 69 /* 70 * TODO 71 * 72 * - Resource limits? 73 * - Update fstat(1) 74 * - Replace global sem_lock with mtx_pool locks? 75 * - Add a MAC check_create() hook for creating new named semaphores. 76 */ 77 78 #ifndef SEM_MAX 79 #define SEM_MAX 30 80 #endif 81 82 #ifdef SEM_DEBUG 83 #define DP(x) printf x 84 #else 85 #define DP(x) 86 #endif 87 88 struct ksem_mapping { 89 char *km_path; 90 Fnv32_t km_fnv; 91 struct ksem *km_ksem; 92 LIST_ENTRY(ksem_mapping) km_link; 93 }; 94 95 static MALLOC_DEFINE(M_KSEM, "ksem", "semaphore file descriptor"); 96 static LIST_HEAD(, ksem_mapping) *ksem_dictionary; 97 static struct sx ksem_dict_lock; 98 static struct mtx ksem_count_lock; 99 static struct mtx sem_lock; 100 static u_long ksem_hash; 101 static int ksem_dead; 102 103 #define KSEM_HASH(fnv) (&ksem_dictionary[(fnv) & ksem_hash]) 104 105 static int nsems = 0; 106 SYSCTL_DECL(_p1003_1b); 107 SYSCTL_INT(_p1003_1b, OID_AUTO, nsems, CTLFLAG_RD, &nsems, 0, 108 "Number of active kernel POSIX semaphores"); 109 110 static int kern_sem_wait(struct thread *td, semid_t id, int tryflag, 111 struct timespec *abstime); 112 static int ksem_access(struct ksem *ks, struct ucred *ucred); 113 static struct ksem *ksem_alloc(struct ucred *ucred, mode_t mode, 114 unsigned int value); 115 static int ksem_create(struct thread *td, const char *path, 116 semid_t *semidp, mode_t mode, unsigned int value, 117 int flags, int compat32); 118 static void ksem_drop(struct ksem *ks); 119 static int ksem_get(struct thread *td, semid_t id, struct file **fpp); 120 static struct ksem *ksem_hold(struct ksem *ks); 121 static void ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks); 122 static struct ksem *ksem_lookup(char *path, Fnv32_t fnv); 123 static void ksem_module_destroy(void); 124 static int ksem_module_init(void); 125 static int ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred); 126 static int sem_modload(struct module *module, int cmd, void *arg); 127 128 static fo_rdwr_t ksem_read; 129 static fo_rdwr_t ksem_write; 130 static fo_truncate_t ksem_truncate; 131 static fo_ioctl_t ksem_ioctl; 132 static fo_poll_t ksem_poll; 133 static fo_kqfilter_t ksem_kqfilter; 134 static fo_stat_t ksem_stat; 135 static fo_close_t ksem_closef; 136 137 /* File descriptor operations. */ 138 static struct fileops ksem_ops = { 139 .fo_read = ksem_read, 140 .fo_write = ksem_write, 141 .fo_truncate = ksem_truncate, 142 .fo_ioctl = ksem_ioctl, 143 .fo_poll = ksem_poll, 144 .fo_kqfilter = ksem_kqfilter, 145 .fo_stat = ksem_stat, 146 .fo_close = ksem_closef, 147 .fo_flags = DFLAG_PASSABLE 148 }; 149 150 FEATURE(posix_sem, "POSIX semaphores"); 151 152 static int 153 ksem_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 154 int flags, struct thread *td) 155 { 156 157 return (EOPNOTSUPP); 158 } 159 160 static int 161 ksem_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 162 int flags, struct thread *td) 163 { 164 165 return (EOPNOTSUPP); 166 } 167 168 static int 169 ksem_truncate(struct file *fp, off_t length, struct ucred *active_cred, 170 struct thread *td) 171 { 172 173 return (EINVAL); 174 } 175 176 static int 177 ksem_ioctl(struct file *fp, u_long com, void *data, 178 struct ucred *active_cred, struct thread *td) 179 { 180 181 return (EOPNOTSUPP); 182 } 183 184 static int 185 ksem_poll(struct file *fp, int events, struct ucred *active_cred, 186 struct thread *td) 187 { 188 189 return (EOPNOTSUPP); 190 } 191 192 static int 193 ksem_kqfilter(struct file *fp, struct knote *kn) 194 { 195 196 return (EOPNOTSUPP); 197 } 198 199 static int 200 ksem_stat(struct file *fp, struct stat *sb, struct ucred *active_cred, 201 struct thread *td) 202 { 203 struct ksem *ks; 204 #ifdef MAC 205 int error; 206 #endif 207 208 ks = fp->f_data; 209 210 #ifdef MAC 211 error = mac_posixsem_check_stat(active_cred, fp->f_cred, ks); 212 if (error) 213 return (error); 214 #endif 215 216 /* 217 * Attempt to return sanish values for fstat() on a semaphore 218 * file descriptor. 219 */ 220 bzero(sb, sizeof(*sb)); 221 sb->st_mode = S_IFREG | ks->ks_mode; /* XXX */ 222 223 sb->st_atimespec = ks->ks_atime; 224 sb->st_ctimespec = ks->ks_ctime; 225 sb->st_mtimespec = ks->ks_mtime; 226 sb->st_birthtimespec = ks->ks_birthtime; 227 sb->st_uid = ks->ks_uid; 228 sb->st_gid = ks->ks_gid; 229 230 return (0); 231 } 232 233 static int 234 ksem_closef(struct file *fp, struct thread *td) 235 { 236 struct ksem *ks; 237 238 ks = fp->f_data; 239 fp->f_data = NULL; 240 ksem_drop(ks); 241 242 return (0); 243 } 244 245 /* 246 * ksem object management including creation and reference counting 247 * routines. 248 */ 249 static struct ksem * 250 ksem_alloc(struct ucred *ucred, mode_t mode, unsigned int value) 251 { 252 struct ksem *ks; 253 254 mtx_lock(&ksem_count_lock); 255 if (nsems == p31b_getcfg(CTL_P1003_1B_SEM_NSEMS_MAX) || ksem_dead) { 256 mtx_unlock(&ksem_count_lock); 257 return (NULL); 258 } 259 nsems++; 260 mtx_unlock(&ksem_count_lock); 261 ks = malloc(sizeof(*ks), M_KSEM, M_WAITOK | M_ZERO); 262 ks->ks_uid = ucred->cr_uid; 263 ks->ks_gid = ucred->cr_gid; 264 ks->ks_mode = mode; 265 ks->ks_value = value; 266 cv_init(&ks->ks_cv, "ksem"); 267 vfs_timestamp(&ks->ks_birthtime); 268 ks->ks_atime = ks->ks_mtime = ks->ks_ctime = ks->ks_birthtime; 269 refcount_init(&ks->ks_ref, 1); 270 #ifdef MAC 271 mac_posixsem_init(ks); 272 mac_posixsem_create(ucred, ks); 273 #endif 274 275 return (ks); 276 } 277 278 static struct ksem * 279 ksem_hold(struct ksem *ks) 280 { 281 282 refcount_acquire(&ks->ks_ref); 283 return (ks); 284 } 285 286 static void 287 ksem_drop(struct ksem *ks) 288 { 289 290 if (refcount_release(&ks->ks_ref)) { 291 #ifdef MAC 292 mac_posixsem_destroy(ks); 293 #endif 294 cv_destroy(&ks->ks_cv); 295 free(ks, M_KSEM); 296 mtx_lock(&ksem_count_lock); 297 nsems--; 298 mtx_unlock(&ksem_count_lock); 299 } 300 } 301 302 /* 303 * Determine if the credentials have sufficient permissions for read 304 * and write access. 305 */ 306 static int 307 ksem_access(struct ksem *ks, struct ucred *ucred) 308 { 309 int error; 310 311 error = vaccess(VREG, ks->ks_mode, ks->ks_uid, ks->ks_gid, 312 VREAD | VWRITE, ucred, NULL); 313 if (error) 314 error = priv_check_cred(ucred, PRIV_SEM_WRITE, 0); 315 return (error); 316 } 317 318 /* 319 * Dictionary management. We maintain an in-kernel dictionary to map 320 * paths to semaphore objects. We use the FNV hash on the path to 321 * store the mappings in a hash table. 322 */ 323 static struct ksem * 324 ksem_lookup(char *path, Fnv32_t fnv) 325 { 326 struct ksem_mapping *map; 327 328 LIST_FOREACH(map, KSEM_HASH(fnv), km_link) { 329 if (map->km_fnv != fnv) 330 continue; 331 if (strcmp(map->km_path, path) == 0) 332 return (map->km_ksem); 333 } 334 335 return (NULL); 336 } 337 338 static void 339 ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks) 340 { 341 struct ksem_mapping *map; 342 343 map = malloc(sizeof(struct ksem_mapping), M_KSEM, M_WAITOK); 344 map->km_path = path; 345 map->km_fnv = fnv; 346 map->km_ksem = ksem_hold(ks); 347 LIST_INSERT_HEAD(KSEM_HASH(fnv), map, km_link); 348 } 349 350 static int 351 ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 352 { 353 struct ksem_mapping *map; 354 int error; 355 356 LIST_FOREACH(map, KSEM_HASH(fnv), km_link) { 357 if (map->km_fnv != fnv) 358 continue; 359 if (strcmp(map->km_path, path) == 0) { 360 #ifdef MAC 361 error = mac_posixsem_check_unlink(ucred, map->km_ksem); 362 if (error) 363 return (error); 364 #endif 365 error = ksem_access(map->km_ksem, ucred); 366 if (error) 367 return (error); 368 LIST_REMOVE(map, km_link); 369 ksem_drop(map->km_ksem); 370 free(map->km_path, M_KSEM); 371 free(map, M_KSEM); 372 return (0); 373 } 374 } 375 376 return (ENOENT); 377 } 378 379 static int 380 ksem_create_copyout_semid(struct thread *td, semid_t *semidp, int fd, 381 int compat32) 382 { 383 semid_t semid; 384 #ifdef COMPAT_FREEBSD32 385 int32_t semid32; 386 #endif 387 void *ptr; 388 size_t ptrs; 389 390 #ifdef COMPAT_FREEBSD32 391 if (compat32) { 392 semid32 = fd; 393 ptr = &semid32; 394 ptrs = sizeof(semid32); 395 } else { 396 #endif 397 semid = fd; 398 ptr = &semid; 399 ptrs = sizeof(semid); 400 compat32 = 0; /* silence gcc */ 401 #ifdef COMPAT_FREEBSD32 402 } 403 #endif 404 405 return (copyout(ptr, semidp, ptrs)); 406 } 407 408 /* Other helper routines. */ 409 static int 410 ksem_create(struct thread *td, const char *name, semid_t *semidp, mode_t mode, 411 unsigned int value, int flags, int compat32) 412 { 413 struct filedesc *fdp; 414 struct ksem *ks; 415 struct file *fp; 416 char *path; 417 Fnv32_t fnv; 418 int error, fd; 419 420 if (value > SEM_VALUE_MAX) 421 return (EINVAL); 422 423 fdp = td->td_proc->p_fd; 424 mode = (mode & ~fdp->fd_cmask) & ACCESSPERMS; 425 error = falloc(td, &fp, &fd); 426 if (error) { 427 if (name == NULL) 428 error = ENOSPC; 429 return (error); 430 } 431 432 /* 433 * Go ahead and copyout the file descriptor now. This is a bit 434 * premature, but it is a lot easier to handle errors as opposed 435 * to later when we've possibly created a new semaphore, etc. 436 */ 437 error = ksem_create_copyout_semid(td, semidp, fd, compat32); 438 if (error) { 439 fdclose(fdp, fp, fd, td); 440 fdrop(fp, td); 441 return (error); 442 } 443 444 if (name == NULL) { 445 /* Create an anonymous semaphore. */ 446 ks = ksem_alloc(td->td_ucred, mode, value); 447 if (ks == NULL) 448 error = ENOSPC; 449 else 450 ks->ks_flags |= KS_ANONYMOUS; 451 } else { 452 path = malloc(MAXPATHLEN, M_KSEM, M_WAITOK); 453 error = copyinstr(name, path, MAXPATHLEN, NULL); 454 455 /* Require paths to start with a '/' character. */ 456 if (error == 0 && path[0] != '/') 457 error = EINVAL; 458 if (error) { 459 fdclose(fdp, fp, fd, td); 460 fdrop(fp, td); 461 free(path, M_KSEM); 462 return (error); 463 } 464 465 fnv = fnv_32_str(path, FNV1_32_INIT); 466 sx_xlock(&ksem_dict_lock); 467 ks = ksem_lookup(path, fnv); 468 if (ks == NULL) { 469 /* Object does not exist, create it if requested. */ 470 if (flags & O_CREAT) { 471 ks = ksem_alloc(td->td_ucred, mode, value); 472 if (ks == NULL) 473 error = ENFILE; 474 else { 475 ksem_insert(path, fnv, ks); 476 path = NULL; 477 } 478 } else 479 error = ENOENT; 480 } else { 481 /* 482 * Object already exists, obtain a new 483 * reference if requested and permitted. 484 */ 485 if ((flags & (O_CREAT | O_EXCL)) == 486 (O_CREAT | O_EXCL)) 487 error = EEXIST; 488 else { 489 #ifdef MAC 490 error = mac_posixsem_check_open(td->td_ucred, 491 ks); 492 if (error == 0) 493 #endif 494 error = ksem_access(ks, td->td_ucred); 495 } 496 if (error == 0) 497 ksem_hold(ks); 498 #ifdef INVARIANTS 499 else 500 ks = NULL; 501 #endif 502 } 503 sx_xunlock(&ksem_dict_lock); 504 if (path) 505 free(path, M_KSEM); 506 } 507 508 if (error) { 509 KASSERT(ks == NULL, ("ksem_create error with a ksem")); 510 fdclose(fdp, fp, fd, td); 511 fdrop(fp, td); 512 return (error); 513 } 514 KASSERT(ks != NULL, ("ksem_create w/o a ksem")); 515 516 finit(fp, FREAD | FWRITE, DTYPE_SEM, ks, &ksem_ops); 517 518 FILEDESC_XLOCK(fdp); 519 if (fdp->fd_ofiles[fd] == fp) 520 fdp->fd_ofileflags[fd] |= UF_EXCLOSE; 521 FILEDESC_XUNLOCK(fdp); 522 fdrop(fp, td); 523 524 return (0); 525 } 526 527 static int 528 ksem_get(struct thread *td, semid_t id, struct file **fpp) 529 { 530 struct ksem *ks; 531 struct file *fp; 532 int error; 533 534 error = fget(td, id, &fp); 535 if (error) 536 return (EINVAL); 537 if (fp->f_type != DTYPE_SEM) { 538 fdrop(fp, td); 539 return (EINVAL); 540 } 541 ks = fp->f_data; 542 if (ks->ks_flags & KS_DEAD) { 543 fdrop(fp, td); 544 return (EINVAL); 545 } 546 *fpp = fp; 547 return (0); 548 } 549 550 /* System calls. */ 551 #ifndef _SYS_SYSPROTO_H_ 552 struct ksem_init_args { 553 unsigned int value; 554 semid_t *idp; 555 }; 556 #endif 557 int 558 ksem_init(struct thread *td, struct ksem_init_args *uap) 559 { 560 561 return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value, 562 0, 0)); 563 } 564 565 #ifndef _SYS_SYSPROTO_H_ 566 struct ksem_open_args { 567 char *name; 568 int oflag; 569 mode_t mode; 570 unsigned int value; 571 semid_t *idp; 572 }; 573 #endif 574 int 575 ksem_open(struct thread *td, struct ksem_open_args *uap) 576 { 577 578 DP((">>> ksem_open start, pid=%d\n", (int)td->td_proc->p_pid)); 579 580 if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0) 581 return (EINVAL); 582 return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value, 583 uap->oflag, 0)); 584 } 585 586 #ifndef _SYS_SYSPROTO_H_ 587 struct ksem_unlink_args { 588 char *name; 589 }; 590 #endif 591 int 592 ksem_unlink(struct thread *td, struct ksem_unlink_args *uap) 593 { 594 char *path; 595 Fnv32_t fnv; 596 int error; 597 598 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 599 error = copyinstr(uap->name, path, MAXPATHLEN, NULL); 600 if (error) { 601 free(path, M_TEMP); 602 return (error); 603 } 604 605 fnv = fnv_32_str(path, FNV1_32_INIT); 606 sx_xlock(&ksem_dict_lock); 607 error = ksem_remove(path, fnv, td->td_ucred); 608 sx_xunlock(&ksem_dict_lock); 609 free(path, M_TEMP); 610 611 return (error); 612 } 613 614 #ifndef _SYS_SYSPROTO_H_ 615 struct ksem_close_args { 616 semid_t id; 617 }; 618 #endif 619 int 620 ksem_close(struct thread *td, struct ksem_close_args *uap) 621 { 622 struct ksem *ks; 623 struct file *fp; 624 int error; 625 626 error = ksem_get(td, uap->id, &fp); 627 if (error) 628 return (error); 629 ks = fp->f_data; 630 if (ks->ks_flags & KS_ANONYMOUS) { 631 fdrop(fp, td); 632 return (EINVAL); 633 } 634 error = kern_close(td, uap->id); 635 fdrop(fp, td); 636 return (error); 637 } 638 639 #ifndef _SYS_SYSPROTO_H_ 640 struct ksem_post_args { 641 semid_t id; 642 }; 643 #endif 644 int 645 ksem_post(struct thread *td, struct ksem_post_args *uap) 646 { 647 struct file *fp; 648 struct ksem *ks; 649 int error; 650 651 error = ksem_get(td, uap->id, &fp); 652 if (error) 653 return (error); 654 ks = fp->f_data; 655 656 mtx_lock(&sem_lock); 657 #ifdef MAC 658 error = mac_posixsem_check_post(td->td_ucred, fp->f_cred, ks); 659 if (error) 660 goto err; 661 #endif 662 if (ks->ks_value == SEM_VALUE_MAX) { 663 error = EOVERFLOW; 664 goto err; 665 } 666 ++ks->ks_value; 667 if (ks->ks_waiters > 0) 668 cv_signal(&ks->ks_cv); 669 error = 0; 670 vfs_timestamp(&ks->ks_ctime); 671 err: 672 mtx_unlock(&sem_lock); 673 fdrop(fp, td); 674 return (error); 675 } 676 677 #ifndef _SYS_SYSPROTO_H_ 678 struct ksem_wait_args { 679 semid_t id; 680 }; 681 #endif 682 int 683 ksem_wait(struct thread *td, struct ksem_wait_args *uap) 684 { 685 686 return (kern_sem_wait(td, uap->id, 0, NULL)); 687 } 688 689 #ifndef _SYS_SYSPROTO_H_ 690 struct ksem_timedwait_args { 691 semid_t id; 692 const struct timespec *abstime; 693 }; 694 #endif 695 int 696 ksem_timedwait(struct thread *td, struct ksem_timedwait_args *uap) 697 { 698 struct timespec abstime; 699 struct timespec *ts; 700 int error; 701 702 /* 703 * We allow a null timespec (wait forever). 704 */ 705 if (uap->abstime == NULL) 706 ts = NULL; 707 else { 708 error = copyin(uap->abstime, &abstime, sizeof(abstime)); 709 if (error != 0) 710 return (error); 711 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0) 712 return (EINVAL); 713 ts = &abstime; 714 } 715 return (kern_sem_wait(td, uap->id, 0, ts)); 716 } 717 718 #ifndef _SYS_SYSPROTO_H_ 719 struct ksem_trywait_args { 720 semid_t id; 721 }; 722 #endif 723 int 724 ksem_trywait(struct thread *td, struct ksem_trywait_args *uap) 725 { 726 727 return (kern_sem_wait(td, uap->id, 1, NULL)); 728 } 729 730 static int 731 kern_sem_wait(struct thread *td, semid_t id, int tryflag, 732 struct timespec *abstime) 733 { 734 struct timespec ts1, ts2; 735 struct timeval tv; 736 struct file *fp; 737 struct ksem *ks; 738 int error; 739 740 DP((">>> kern_sem_wait entered! pid=%d\n", (int)td->td_proc->p_pid)); 741 error = ksem_get(td, id, &fp); 742 if (error) 743 return (error); 744 ks = fp->f_data; 745 mtx_lock(&sem_lock); 746 DP((">>> kern_sem_wait critical section entered! pid=%d\n", 747 (int)td->td_proc->p_pid)); 748 #ifdef MAC 749 error = mac_posixsem_check_wait(td->td_ucred, fp->f_cred, ks); 750 if (error) { 751 DP(("kern_sem_wait mac failed\n")); 752 goto err; 753 } 754 #endif 755 DP(("kern_sem_wait value = %d, tryflag %d\n", ks->ks_value, tryflag)); 756 vfs_timestamp(&ks->ks_atime); 757 while (ks->ks_value == 0) { 758 ks->ks_waiters++; 759 if (tryflag != 0) 760 error = EAGAIN; 761 else if (abstime == NULL) 762 error = cv_wait_sig(&ks->ks_cv, &sem_lock); 763 else { 764 for (;;) { 765 ts1 = *abstime; 766 getnanotime(&ts2); 767 timespecsub(&ts1, &ts2); 768 TIMESPEC_TO_TIMEVAL(&tv, &ts1); 769 if (tv.tv_sec < 0) { 770 error = ETIMEDOUT; 771 break; 772 } 773 error = cv_timedwait_sig(&ks->ks_cv, 774 &sem_lock, tvtohz(&tv)); 775 if (error != EWOULDBLOCK) 776 break; 777 } 778 } 779 ks->ks_waiters--; 780 if (error) 781 goto err; 782 } 783 ks->ks_value--; 784 DP(("kern_sem_wait value post-decrement = %d\n", ks->ks_value)); 785 error = 0; 786 err: 787 mtx_unlock(&sem_lock); 788 fdrop(fp, td); 789 DP(("<<< kern_sem_wait leaving, pid=%d, error = %d\n", 790 (int)td->td_proc->p_pid, error)); 791 return (error); 792 } 793 794 #ifndef _SYS_SYSPROTO_H_ 795 struct ksem_getvalue_args { 796 semid_t id; 797 int *val; 798 }; 799 #endif 800 int 801 ksem_getvalue(struct thread *td, struct ksem_getvalue_args *uap) 802 { 803 struct file *fp; 804 struct ksem *ks; 805 int error, val; 806 807 error = ksem_get(td, uap->id, &fp); 808 if (error) 809 return (error); 810 ks = fp->f_data; 811 812 mtx_lock(&sem_lock); 813 #ifdef MAC 814 error = mac_posixsem_check_getvalue(td->td_ucred, fp->f_cred, ks); 815 if (error) { 816 mtx_unlock(&sem_lock); 817 fdrop(fp, td); 818 return (error); 819 } 820 #endif 821 val = ks->ks_value; 822 vfs_timestamp(&ks->ks_atime); 823 mtx_unlock(&sem_lock); 824 fdrop(fp, td); 825 error = copyout(&val, uap->val, sizeof(val)); 826 return (error); 827 } 828 829 #ifndef _SYS_SYSPROTO_H_ 830 struct ksem_destroy_args { 831 semid_t id; 832 }; 833 #endif 834 int 835 ksem_destroy(struct thread *td, struct ksem_destroy_args *uap) 836 { 837 struct file *fp; 838 struct ksem *ks; 839 int error; 840 841 error = ksem_get(td, uap->id, &fp); 842 if (error) 843 return (error); 844 ks = fp->f_data; 845 if (!(ks->ks_flags & KS_ANONYMOUS)) { 846 fdrop(fp, td); 847 return (EINVAL); 848 } 849 mtx_lock(&sem_lock); 850 if (ks->ks_waiters != 0) { 851 mtx_unlock(&sem_lock); 852 error = EBUSY; 853 goto err; 854 } 855 ks->ks_flags |= KS_DEAD; 856 mtx_unlock(&sem_lock); 857 858 error = kern_close(td, uap->id); 859 err: 860 fdrop(fp, td); 861 return (error); 862 } 863 864 static struct syscall_helper_data ksem_syscalls[] = { 865 SYSCALL_INIT_HELPER(ksem_init), 866 SYSCALL_INIT_HELPER(ksem_open), 867 SYSCALL_INIT_HELPER(ksem_unlink), 868 SYSCALL_INIT_HELPER(ksem_close), 869 SYSCALL_INIT_HELPER(ksem_post), 870 SYSCALL_INIT_HELPER(ksem_wait), 871 SYSCALL_INIT_HELPER(ksem_timedwait), 872 SYSCALL_INIT_HELPER(ksem_trywait), 873 SYSCALL_INIT_HELPER(ksem_getvalue), 874 SYSCALL_INIT_HELPER(ksem_destroy), 875 SYSCALL_INIT_LAST 876 }; 877 878 #ifdef COMPAT_FREEBSD32 879 #include <compat/freebsd32/freebsd32.h> 880 #include <compat/freebsd32/freebsd32_proto.h> 881 #include <compat/freebsd32/freebsd32_signal.h> 882 #include <compat/freebsd32/freebsd32_syscall.h> 883 #include <compat/freebsd32/freebsd32_util.h> 884 885 int 886 freebsd32_ksem_init(struct thread *td, struct freebsd32_ksem_init_args *uap) 887 { 888 889 return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value, 890 0, 1)); 891 } 892 893 int 894 freebsd32_ksem_open(struct thread *td, struct freebsd32_ksem_open_args *uap) 895 { 896 897 if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0) 898 return (EINVAL); 899 return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value, 900 uap->oflag, 1)); 901 } 902 903 int 904 freebsd32_ksem_timedwait(struct thread *td, 905 struct freebsd32_ksem_timedwait_args *uap) 906 { 907 struct timespec32 abstime32; 908 struct timespec *ts, abstime; 909 int error; 910 911 /* 912 * We allow a null timespec (wait forever). 913 */ 914 if (uap->abstime == NULL) 915 ts = NULL; 916 else { 917 error = copyin(uap->abstime, &abstime32, sizeof(abstime32)); 918 if (error != 0) 919 return (error); 920 CP(abstime32, abstime, tv_sec); 921 CP(abstime32, abstime, tv_nsec); 922 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0) 923 return (EINVAL); 924 ts = &abstime; 925 } 926 return (kern_sem_wait(td, uap->id, 0, ts)); 927 } 928 929 static struct syscall_helper_data ksem32_syscalls[] = { 930 SYSCALL32_INIT_HELPER(freebsd32_ksem_init), 931 SYSCALL32_INIT_HELPER(freebsd32_ksem_open), 932 SYSCALL32_INIT_HELPER(ksem_unlink), 933 SYSCALL32_INIT_HELPER(ksem_close), 934 SYSCALL32_INIT_HELPER(ksem_post), 935 SYSCALL32_INIT_HELPER(ksem_wait), 936 SYSCALL32_INIT_HELPER(freebsd32_ksem_timedwait), 937 SYSCALL32_INIT_HELPER(ksem_trywait), 938 SYSCALL32_INIT_HELPER(ksem_getvalue), 939 SYSCALL32_INIT_HELPER(ksem_destroy), 940 SYSCALL_INIT_LAST 941 }; 942 #endif 943 944 static int 945 ksem_module_init(void) 946 { 947 int error; 948 949 mtx_init(&sem_lock, "sem", NULL, MTX_DEF); 950 mtx_init(&ksem_count_lock, "ksem count", NULL, MTX_DEF); 951 sx_init(&ksem_dict_lock, "ksem dictionary"); 952 ksem_dictionary = hashinit(1024, M_KSEM, &ksem_hash); 953 p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 200112L); 954 p31b_setcfg(CTL_P1003_1B_SEM_NSEMS_MAX, SEM_MAX); 955 p31b_setcfg(CTL_P1003_1B_SEM_VALUE_MAX, SEM_VALUE_MAX); 956 957 error = syscall_helper_register(ksem_syscalls); 958 if (error) 959 return (error); 960 #ifdef COMPAT_FREEBSD32 961 error = syscall32_helper_register(ksem32_syscalls); 962 if (error) 963 return (error); 964 #endif 965 return (0); 966 } 967 968 static void 969 ksem_module_destroy(void) 970 { 971 972 #ifdef COMPAT_FREEBSD32 973 syscall32_helper_unregister(ksem32_syscalls); 974 #endif 975 syscall_helper_unregister(ksem_syscalls); 976 977 p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 0); 978 hashdestroy(ksem_dictionary, M_KSEM, ksem_hash); 979 sx_destroy(&ksem_dict_lock); 980 mtx_destroy(&ksem_count_lock); 981 mtx_destroy(&sem_lock); 982 p31b_unsetcfg(CTL_P1003_1B_SEM_VALUE_MAX); 983 p31b_unsetcfg(CTL_P1003_1B_SEM_NSEMS_MAX); 984 } 985 986 static int 987 sem_modload(struct module *module, int cmd, void *arg) 988 { 989 int error = 0; 990 991 switch (cmd) { 992 case MOD_LOAD: 993 error = ksem_module_init(); 994 if (error) 995 ksem_module_destroy(); 996 break; 997 998 case MOD_UNLOAD: 999 mtx_lock(&ksem_count_lock); 1000 if (nsems != 0) { 1001 error = EOPNOTSUPP; 1002 mtx_unlock(&ksem_count_lock); 1003 break; 1004 } 1005 ksem_dead = 1; 1006 mtx_unlock(&ksem_count_lock); 1007 ksem_module_destroy(); 1008 break; 1009 1010 case MOD_SHUTDOWN: 1011 break; 1012 default: 1013 error = EINVAL; 1014 break; 1015 } 1016 return (error); 1017 } 1018 1019 static moduledata_t sem_mod = { 1020 "sem", 1021 &sem_modload, 1022 NULL 1023 }; 1024 1025 DECLARE_MODULE(sem, sem_mod, SI_SUB_SYSV_SEM, SI_ORDER_FIRST); 1026 MODULE_VERSION(sem, 1);
Cache object: 0430d27daa8da0324d1b39947463f82b
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