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("$FreeBSD$"); 36 37 #include "opt_mac.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); 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 /* Other helper routines. */ 380 static int 381 ksem_create(struct thread *td, const char *name, semid_t *semidp, mode_t mode, 382 unsigned int value, int flags) 383 { 384 struct filedesc *fdp; 385 struct ksem *ks; 386 struct file *fp; 387 char *path; 388 semid_t semid; 389 Fnv32_t fnv; 390 int error, fd; 391 392 if (value > SEM_VALUE_MAX) 393 return (EINVAL); 394 395 fdp = td->td_proc->p_fd; 396 mode = (mode & ~fdp->fd_cmask) & ACCESSPERMS; 397 error = falloc(td, &fp, &fd); 398 if (error) { 399 if (name == NULL) 400 error = ENOSPC; 401 return (error); 402 } 403 404 /* 405 * Go ahead and copyout the file descriptor now. This is a bit 406 * premature, but it is a lot easier to handle errors as opposed 407 * to later when we've possibly created a new semaphore, etc. 408 */ 409 semid = fd; 410 error = copyout(&semid, semidp, sizeof(semid)); 411 if (error) { 412 fdclose(fdp, fp, fd, td); 413 fdrop(fp, td); 414 return (error); 415 } 416 417 if (name == NULL) { 418 /* Create an anonymous semaphore. */ 419 ks = ksem_alloc(td->td_ucred, mode, value); 420 if (ks == NULL) 421 error = ENOSPC; 422 else 423 ks->ks_flags |= KS_ANONYMOUS; 424 } else { 425 path = malloc(MAXPATHLEN, M_KSEM, M_WAITOK); 426 error = copyinstr(name, path, MAXPATHLEN, NULL); 427 428 /* Require paths to start with a '/' character. */ 429 if (error == 0 && path[0] != '/') 430 error = EINVAL; 431 if (error) { 432 fdclose(fdp, fp, fd, td); 433 fdrop(fp, td); 434 free(path, M_KSEM); 435 return (error); 436 } 437 438 fnv = fnv_32_str(path, FNV1_32_INIT); 439 sx_xlock(&ksem_dict_lock); 440 ks = ksem_lookup(path, fnv); 441 if (ks == NULL) { 442 /* Object does not exist, create it if requested. */ 443 if (flags & O_CREAT) { 444 ks = ksem_alloc(td->td_ucred, mode, value); 445 if (ks == NULL) 446 error = ENFILE; 447 else { 448 ksem_insert(path, fnv, ks); 449 path = NULL; 450 } 451 } else 452 error = ENOENT; 453 } else { 454 /* 455 * Object already exists, obtain a new 456 * reference if requested and permitted. 457 */ 458 if ((flags & (O_CREAT | O_EXCL)) == 459 (O_CREAT | O_EXCL)) 460 error = EEXIST; 461 else { 462 #ifdef MAC 463 error = mac_posixsem_check_open(td->td_ucred, 464 ks); 465 if (error == 0) 466 #endif 467 error = ksem_access(ks, td->td_ucred); 468 } 469 if (error == 0) 470 ksem_hold(ks); 471 #ifdef INVARIANTS 472 else 473 ks = NULL; 474 #endif 475 } 476 sx_xunlock(&ksem_dict_lock); 477 if (path) 478 free(path, M_KSEM); 479 } 480 481 if (error) { 482 KASSERT(ks == NULL, ("ksem_create error with a ksem")); 483 fdclose(fdp, fp, fd, td); 484 fdrop(fp, td); 485 return (error); 486 } 487 KASSERT(ks != NULL, ("ksem_create w/o a ksem")); 488 489 finit(fp, FREAD | FWRITE, DTYPE_SEM, ks, &ksem_ops); 490 491 FILEDESC_XLOCK(fdp); 492 if (fdp->fd_ofiles[fd] == fp) 493 fdp->fd_ofileflags[fd] |= UF_EXCLOSE; 494 FILEDESC_XUNLOCK(fdp); 495 fdrop(fp, td); 496 497 return (0); 498 } 499 500 static int 501 ksem_get(struct thread *td, semid_t id, struct file **fpp) 502 { 503 struct ksem *ks; 504 struct file *fp; 505 int error; 506 507 error = fget(td, id, &fp); 508 if (error) 509 return (EINVAL); 510 if (fp->f_type != DTYPE_SEM) { 511 fdrop(fp, td); 512 return (EINVAL); 513 } 514 ks = fp->f_data; 515 if (ks->ks_flags & KS_DEAD) { 516 fdrop(fp, td); 517 return (EINVAL); 518 } 519 *fpp = fp; 520 return (0); 521 } 522 523 /* System calls. */ 524 #ifndef _SYS_SYSPROTO_H_ 525 struct ksem_init_args { 526 unsigned int value; 527 semid_t *idp; 528 }; 529 #endif 530 int 531 ksem_init(struct thread *td, struct ksem_init_args *uap) 532 { 533 534 return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value, 535 0)); 536 } 537 538 #ifndef _SYS_SYSPROTO_H_ 539 struct ksem_open_args { 540 char *name; 541 int oflag; 542 mode_t mode; 543 unsigned int value; 544 semid_t *idp; 545 }; 546 #endif 547 int 548 ksem_open(struct thread *td, struct ksem_open_args *uap) 549 { 550 551 DP((">>> ksem_open start, pid=%d\n", (int)td->td_proc->p_pid)); 552 553 if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0) 554 return (EINVAL); 555 return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value, 556 uap->oflag)); 557 } 558 559 #ifndef _SYS_SYSPROTO_H_ 560 struct ksem_unlink_args { 561 char *name; 562 }; 563 #endif 564 int 565 ksem_unlink(struct thread *td, struct ksem_unlink_args *uap) 566 { 567 char *path; 568 Fnv32_t fnv; 569 int error; 570 571 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 572 error = copyinstr(uap->name, path, MAXPATHLEN, NULL); 573 if (error) { 574 free(path, M_TEMP); 575 return (error); 576 } 577 578 fnv = fnv_32_str(path, FNV1_32_INIT); 579 sx_xlock(&ksem_dict_lock); 580 error = ksem_remove(path, fnv, td->td_ucred); 581 sx_xunlock(&ksem_dict_lock); 582 free(path, M_TEMP); 583 584 return (error); 585 } 586 587 #ifndef _SYS_SYSPROTO_H_ 588 struct ksem_close_args { 589 semid_t id; 590 }; 591 #endif 592 int 593 ksem_close(struct thread *td, struct ksem_close_args *uap) 594 { 595 struct ksem *ks; 596 struct file *fp; 597 int error; 598 599 error = ksem_get(td, uap->id, &fp); 600 if (error) 601 return (error); 602 ks = fp->f_data; 603 if (ks->ks_flags & KS_ANONYMOUS) { 604 fdrop(fp, td); 605 return (EINVAL); 606 } 607 error = kern_close(td, uap->id); 608 fdrop(fp, td); 609 return (error); 610 } 611 612 #ifndef _SYS_SYSPROTO_H_ 613 struct ksem_post_args { 614 semid_t id; 615 }; 616 #endif 617 int 618 ksem_post(struct thread *td, struct ksem_post_args *uap) 619 { 620 struct file *fp; 621 struct ksem *ks; 622 int error; 623 624 error = ksem_get(td, uap->id, &fp); 625 if (error) 626 return (error); 627 ks = fp->f_data; 628 629 mtx_lock(&sem_lock); 630 #ifdef MAC 631 error = mac_posixsem_check_post(td->td_ucred, fp->f_cred, ks); 632 if (error) 633 goto err; 634 #endif 635 if (ks->ks_value == SEM_VALUE_MAX) { 636 error = EOVERFLOW; 637 goto err; 638 } 639 ++ks->ks_value; 640 if (ks->ks_waiters > 0) 641 cv_signal(&ks->ks_cv); 642 error = 0; 643 vfs_timestamp(&ks->ks_ctime); 644 err: 645 mtx_unlock(&sem_lock); 646 fdrop(fp, td); 647 return (error); 648 } 649 650 #ifndef _SYS_SYSPROTO_H_ 651 struct ksem_wait_args { 652 semid_t id; 653 }; 654 #endif 655 int 656 ksem_wait(struct thread *td, struct ksem_wait_args *uap) 657 { 658 659 return (kern_sem_wait(td, uap->id, 0, NULL)); 660 } 661 662 #ifndef _SYS_SYSPROTO_H_ 663 struct ksem_timedwait_args { 664 semid_t id; 665 const struct timespec *abstime; 666 }; 667 #endif 668 int 669 ksem_timedwait(struct thread *td, struct ksem_timedwait_args *uap) 670 { 671 struct timespec abstime; 672 struct timespec *ts; 673 int error; 674 675 /* 676 * We allow a null timespec (wait forever). 677 */ 678 if (uap->abstime == NULL) 679 ts = NULL; 680 else { 681 error = copyin(uap->abstime, &abstime, sizeof(abstime)); 682 if (error != 0) 683 return (error); 684 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0) 685 return (EINVAL); 686 ts = &abstime; 687 } 688 return (kern_sem_wait(td, uap->id, 0, ts)); 689 } 690 691 #ifndef _SYS_SYSPROTO_H_ 692 struct ksem_trywait_args { 693 semid_t id; 694 }; 695 #endif 696 int 697 ksem_trywait(struct thread *td, struct ksem_trywait_args *uap) 698 { 699 700 return (kern_sem_wait(td, uap->id, 1, NULL)); 701 } 702 703 static int 704 kern_sem_wait(struct thread *td, semid_t id, int tryflag, 705 struct timespec *abstime) 706 { 707 struct timespec ts1, ts2; 708 struct timeval tv; 709 struct file *fp; 710 struct ksem *ks; 711 int error; 712 713 DP((">>> kern_sem_wait entered! pid=%d\n", (int)td->td_proc->p_pid)); 714 error = ksem_get(td, id, &fp); 715 if (error) 716 return (error); 717 ks = fp->f_data; 718 mtx_lock(&sem_lock); 719 DP((">>> kern_sem_wait critical section entered! pid=%d\n", 720 (int)td->td_proc->p_pid)); 721 #ifdef MAC 722 error = mac_posixsem_check_wait(td->td_ucred, fp->f_cred, ks); 723 if (error) { 724 DP(("kern_sem_wait mac failed\n")); 725 goto err; 726 } 727 #endif 728 DP(("kern_sem_wait value = %d, tryflag %d\n", ks->ks_value, tryflag)); 729 vfs_timestamp(&ks->ks_atime); 730 while (ks->ks_value == 0) { 731 ks->ks_waiters++; 732 if (tryflag != 0) 733 error = EAGAIN; 734 else if (abstime == NULL) 735 error = cv_wait_sig(&ks->ks_cv, &sem_lock); 736 else { 737 for (;;) { 738 ts1 = *abstime; 739 getnanotime(&ts2); 740 timespecsub(&ts1, &ts2); 741 TIMESPEC_TO_TIMEVAL(&tv, &ts1); 742 if (tv.tv_sec < 0) { 743 error = ETIMEDOUT; 744 break; 745 } 746 error = cv_timedwait_sig(&ks->ks_cv, 747 &sem_lock, tvtohz(&tv)); 748 if (error != EWOULDBLOCK) 749 break; 750 } 751 } 752 ks->ks_waiters--; 753 if (error) 754 goto err; 755 } 756 ks->ks_value--; 757 DP(("kern_sem_wait value post-decrement = %d\n", ks->ks_value)); 758 error = 0; 759 err: 760 mtx_unlock(&sem_lock); 761 fdrop(fp, td); 762 DP(("<<< kern_sem_wait leaving, pid=%d, error = %d\n", 763 (int)td->td_proc->p_pid, error)); 764 return (error); 765 } 766 767 #ifndef _SYS_SYSPROTO_H_ 768 struct ksem_getvalue_args { 769 semid_t id; 770 int *val; 771 }; 772 #endif 773 int 774 ksem_getvalue(struct thread *td, struct ksem_getvalue_args *uap) 775 { 776 struct file *fp; 777 struct ksem *ks; 778 int error, val; 779 780 error = ksem_get(td, uap->id, &fp); 781 if (error) 782 return (error); 783 ks = fp->f_data; 784 785 mtx_lock(&sem_lock); 786 #ifdef MAC 787 error = mac_posixsem_check_getvalue(td->td_ucred, fp->f_cred, ks); 788 if (error) { 789 mtx_unlock(&sem_lock); 790 fdrop(fp, td); 791 return (error); 792 } 793 #endif 794 val = ks->ks_value; 795 vfs_timestamp(&ks->ks_atime); 796 mtx_unlock(&sem_lock); 797 fdrop(fp, td); 798 error = copyout(&val, uap->val, sizeof(val)); 799 return (error); 800 } 801 802 #ifndef _SYS_SYSPROTO_H_ 803 struct ksem_destroy_args { 804 semid_t id; 805 }; 806 #endif 807 int 808 ksem_destroy(struct thread *td, struct ksem_destroy_args *uap) 809 { 810 struct file *fp; 811 struct ksem *ks; 812 int error; 813 814 error = ksem_get(td, uap->id, &fp); 815 if (error) 816 return (error); 817 ks = fp->f_data; 818 if (!(ks->ks_flags & KS_ANONYMOUS)) { 819 fdrop(fp, td); 820 return (EINVAL); 821 } 822 mtx_lock(&sem_lock); 823 if (ks->ks_waiters != 0) { 824 mtx_unlock(&sem_lock); 825 error = EBUSY; 826 goto err; 827 } 828 ks->ks_flags |= KS_DEAD; 829 mtx_unlock(&sem_lock); 830 831 error = kern_close(td, uap->id); 832 err: 833 fdrop(fp, td); 834 return (error); 835 } 836 837 #define SYSCALL_DATA(syscallname) \ 838 static int syscallname##_syscall = SYS_##syscallname; \ 839 static int syscallname##_registered; \ 840 static struct sysent syscallname##_old_sysent; \ 841 MAKE_SYSENT(syscallname); 842 843 #define SYSCALL_REGISTER(syscallname) do { \ 844 error = syscall_register(& syscallname##_syscall, \ 845 & syscallname##_sysent, & syscallname##_old_sysent); \ 846 if (error) \ 847 return (error); \ 848 syscallname##_registered = 1; \ 849 } while(0) 850 851 #define SYSCALL_DEREGISTER(syscallname) do { \ 852 if (syscallname##_registered) { \ 853 syscallname##_registered = 0; \ 854 syscall_deregister(& syscallname##_syscall, \ 855 & syscallname##_old_sysent); \ 856 } \ 857 } while(0) 858 859 SYSCALL_DATA(ksem_init); 860 SYSCALL_DATA(ksem_open); 861 SYSCALL_DATA(ksem_unlink); 862 SYSCALL_DATA(ksem_close); 863 SYSCALL_DATA(ksem_post); 864 SYSCALL_DATA(ksem_wait); 865 SYSCALL_DATA(ksem_timedwait); 866 SYSCALL_DATA(ksem_trywait); 867 SYSCALL_DATA(ksem_getvalue); 868 SYSCALL_DATA(ksem_destroy); 869 870 static int 871 ksem_module_init(void) 872 { 873 int error; 874 875 mtx_init(&sem_lock, "sem", NULL, MTX_DEF); 876 mtx_init(&ksem_count_lock, "ksem count", NULL, MTX_DEF); 877 sx_init(&ksem_dict_lock, "ksem dictionary"); 878 ksem_dictionary = hashinit(1024, M_KSEM, &ksem_hash); 879 p31b_setcfg(CTL_P1003_1B_SEM_NSEMS_MAX, SEM_MAX); 880 p31b_setcfg(CTL_P1003_1B_SEM_VALUE_MAX, SEM_VALUE_MAX); 881 882 SYSCALL_REGISTER(ksem_init); 883 SYSCALL_REGISTER(ksem_open); 884 SYSCALL_REGISTER(ksem_unlink); 885 SYSCALL_REGISTER(ksem_close); 886 SYSCALL_REGISTER(ksem_post); 887 SYSCALL_REGISTER(ksem_wait); 888 SYSCALL_REGISTER(ksem_timedwait); 889 SYSCALL_REGISTER(ksem_trywait); 890 SYSCALL_REGISTER(ksem_getvalue); 891 SYSCALL_REGISTER(ksem_destroy); 892 return (0); 893 } 894 895 static void 896 ksem_module_destroy(void) 897 { 898 899 SYSCALL_DEREGISTER(ksem_init); 900 SYSCALL_DEREGISTER(ksem_open); 901 SYSCALL_DEREGISTER(ksem_unlink); 902 SYSCALL_DEREGISTER(ksem_close); 903 SYSCALL_DEREGISTER(ksem_post); 904 SYSCALL_DEREGISTER(ksem_wait); 905 SYSCALL_DEREGISTER(ksem_timedwait); 906 SYSCALL_DEREGISTER(ksem_trywait); 907 SYSCALL_DEREGISTER(ksem_getvalue); 908 SYSCALL_DEREGISTER(ksem_destroy); 909 910 hashdestroy(ksem_dictionary, M_KSEM, ksem_hash); 911 sx_destroy(&ksem_dict_lock); 912 mtx_destroy(&ksem_count_lock); 913 mtx_destroy(&sem_lock); 914 } 915 916 static int 917 sem_modload(struct module *module, int cmd, void *arg) 918 { 919 int error = 0; 920 921 switch (cmd) { 922 case MOD_LOAD: 923 error = ksem_module_init(); 924 if (error) 925 ksem_module_destroy(); 926 break; 927 928 case MOD_UNLOAD: 929 mtx_lock(&ksem_count_lock); 930 if (nsems != 0) { 931 error = EOPNOTSUPP; 932 mtx_unlock(&ksem_count_lock); 933 break; 934 } 935 ksem_dead = 1; 936 mtx_unlock(&ksem_count_lock); 937 ksem_module_destroy(); 938 break; 939 940 case MOD_SHUTDOWN: 941 break; 942 default: 943 error = EINVAL; 944 break; 945 } 946 return (error); 947 } 948 949 static moduledata_t sem_mod = { 950 "sem", 951 &sem_modload, 952 NULL 953 }; 954 955 DECLARE_MODULE(sem, sem_mod, SI_SUB_SYSV_SEM, SI_ORDER_FIRST); 956 MODULE_VERSION(sem, 1); 957