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