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_compat.h" 38 #include "opt_posix.h" 39 40 #include <sys/param.h> 41 #include <sys/capability.h> 42 #include <sys/condvar.h> 43 #include <sys/fcntl.h> 44 #include <sys/file.h> 45 #include <sys/filedesc.h> 46 #include <sys/fnv_hash.h> 47 #include <sys/kernel.h> 48 #include <sys/ksem.h> 49 #include <sys/lock.h> 50 #include <sys/malloc.h> 51 #include <sys/module.h> 52 #include <sys/mutex.h> 53 #include <sys/priv.h> 54 #include <sys/proc.h> 55 #include <sys/posix4.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 FEATURE(p1003_1b_semaphores, "POSIX P1003.1B semaphores support"); 70 /* 71 * TODO 72 * 73 * - Resource limits? 74 * - Update fstat(1) 75 * - Replace global sem_lock with mtx_pool locks? 76 * - Add a MAC check_create() hook for creating new named semaphores. 77 */ 78 79 #ifndef SEM_MAX 80 #define SEM_MAX 30 81 #endif 82 83 #ifdef SEM_DEBUG 84 #define DP(x) printf x 85 #else 86 #define DP(x) 87 #endif 88 89 struct ksem_mapping { 90 char *km_path; 91 Fnv32_t km_fnv; 92 struct ksem *km_ksem; 93 LIST_ENTRY(ksem_mapping) km_link; 94 }; 95 96 static MALLOC_DEFINE(M_KSEM, "ksem", "semaphore file descriptor"); 97 static LIST_HEAD(, ksem_mapping) *ksem_dictionary; 98 static struct sx ksem_dict_lock; 99 static struct mtx ksem_count_lock; 100 static struct mtx sem_lock; 101 static u_long ksem_hash; 102 static int ksem_dead; 103 104 #define KSEM_HASH(fnv) (&ksem_dictionary[(fnv) & ksem_hash]) 105 106 static int nsems = 0; 107 SYSCTL_DECL(_p1003_1b); 108 SYSCTL_INT(_p1003_1b, OID_AUTO, nsems, CTLFLAG_RD, &nsems, 0, 109 "Number of active kernel POSIX semaphores"); 110 111 static int kern_sem_wait(struct thread *td, semid_t id, int tryflag, 112 struct timespec *abstime); 113 static int ksem_access(struct ksem *ks, struct ucred *ucred); 114 static struct ksem *ksem_alloc(struct ucred *ucred, mode_t mode, 115 unsigned int value); 116 static int ksem_create(struct thread *td, const char *path, 117 semid_t *semidp, mode_t mode, unsigned int value, 118 int flags, int compat32); 119 static void ksem_drop(struct ksem *ks); 120 static int ksem_get(struct thread *td, semid_t id, cap_rights_t rights, 121 struct file **fpp); 122 static struct ksem *ksem_hold(struct ksem *ks); 123 static void ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks); 124 static struct ksem *ksem_lookup(char *path, Fnv32_t fnv); 125 static void ksem_module_destroy(void); 126 static int ksem_module_init(void); 127 static int ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred); 128 static int sem_modload(struct module *module, int cmd, void *arg); 129 130 static fo_rdwr_t ksem_read; 131 static fo_rdwr_t ksem_write; 132 static fo_truncate_t ksem_truncate; 133 static fo_ioctl_t ksem_ioctl; 134 static fo_poll_t ksem_poll; 135 static fo_kqfilter_t ksem_kqfilter; 136 static fo_stat_t ksem_stat; 137 static fo_close_t ksem_closef; 138 static fo_chmod_t ksem_chmod; 139 static fo_chown_t ksem_chown; 140 141 /* File descriptor operations. */ 142 static struct fileops ksem_ops = { 143 .fo_read = ksem_read, 144 .fo_write = ksem_write, 145 .fo_truncate = ksem_truncate, 146 .fo_ioctl = ksem_ioctl, 147 .fo_poll = ksem_poll, 148 .fo_kqfilter = ksem_kqfilter, 149 .fo_stat = ksem_stat, 150 .fo_close = ksem_closef, 151 .fo_chmod = ksem_chmod, 152 .fo_chown = ksem_chown, 153 .fo_flags = DFLAG_PASSABLE 154 }; 155 156 FEATURE(posix_sem, "POSIX semaphores"); 157 158 static int 159 ksem_read(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_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 168 int flags, struct thread *td) 169 { 170 171 return (EOPNOTSUPP); 172 } 173 174 static int 175 ksem_truncate(struct file *fp, off_t length, struct ucred *active_cred, 176 struct thread *td) 177 { 178 179 return (EINVAL); 180 } 181 182 static int 183 ksem_ioctl(struct file *fp, u_long com, void *data, 184 struct ucred *active_cred, struct thread *td) 185 { 186 187 return (EOPNOTSUPP); 188 } 189 190 static int 191 ksem_poll(struct file *fp, int events, struct ucred *active_cred, 192 struct thread *td) 193 { 194 195 return (EOPNOTSUPP); 196 } 197 198 static int 199 ksem_kqfilter(struct file *fp, struct knote *kn) 200 { 201 202 return (EOPNOTSUPP); 203 } 204 205 static int 206 ksem_stat(struct file *fp, struct stat *sb, struct ucred *active_cred, 207 struct thread *td) 208 { 209 struct ksem *ks; 210 #ifdef MAC 211 int error; 212 #endif 213 214 ks = fp->f_data; 215 216 #ifdef MAC 217 error = mac_posixsem_check_stat(active_cred, fp->f_cred, ks); 218 if (error) 219 return (error); 220 #endif 221 222 /* 223 * Attempt to return sanish values for fstat() on a semaphore 224 * file descriptor. 225 */ 226 bzero(sb, sizeof(*sb)); 227 228 mtx_lock(&sem_lock); 229 sb->st_atim = ks->ks_atime; 230 sb->st_ctim = ks->ks_ctime; 231 sb->st_mtim = ks->ks_mtime; 232 sb->st_birthtim = ks->ks_birthtime; 233 sb->st_uid = ks->ks_uid; 234 sb->st_gid = ks->ks_gid; 235 sb->st_mode = S_IFREG | ks->ks_mode; /* XXX */ 236 mtx_unlock(&sem_lock); 237 238 return (0); 239 } 240 241 static int 242 ksem_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 243 struct thread *td) 244 { 245 struct ksem *ks; 246 int error; 247 248 error = 0; 249 ks = fp->f_data; 250 mtx_lock(&sem_lock); 251 #ifdef MAC 252 error = mac_posixsem_check_setmode(active_cred, ks, mode); 253 if (error != 0) 254 goto out; 255 #endif 256 error = vaccess(VREG, ks->ks_mode, ks->ks_uid, ks->ks_gid, VADMIN, 257 active_cred, NULL); 258 if (error != 0) 259 goto out; 260 ks->ks_mode = mode & ACCESSPERMS; 261 out: 262 mtx_unlock(&sem_lock); 263 return (error); 264 } 265 266 static int 267 ksem_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 268 struct thread *td) 269 { 270 struct ksem *ks; 271 int error; 272 273 error = 0; 274 ks = fp->f_data; 275 mtx_lock(&sem_lock); 276 #ifdef MAC 277 error = mac_posixsem_check_setowner(active_cred, ks, uid, gid); 278 if (error != 0) 279 goto out; 280 #endif 281 if (uid == (uid_t)-1) 282 uid = ks->ks_uid; 283 if (gid == (gid_t)-1) 284 gid = ks->ks_gid; 285 if (((uid != ks->ks_uid && uid != active_cred->cr_uid) || 286 (gid != ks->ks_gid && !groupmember(gid, active_cred))) && 287 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN, 0))) 288 goto out; 289 ks->ks_uid = uid; 290 ks->ks_gid = gid; 291 out: 292 mtx_unlock(&sem_lock); 293 return (error); 294 } 295 296 static int 297 ksem_closef(struct file *fp, struct thread *td) 298 { 299 struct ksem *ks; 300 301 ks = fp->f_data; 302 fp->f_data = NULL; 303 ksem_drop(ks); 304 305 return (0); 306 } 307 308 /* 309 * ksem object management including creation and reference counting 310 * routines. 311 */ 312 static struct ksem * 313 ksem_alloc(struct ucred *ucred, mode_t mode, unsigned int value) 314 { 315 struct ksem *ks; 316 317 mtx_lock(&ksem_count_lock); 318 if (nsems == p31b_getcfg(CTL_P1003_1B_SEM_NSEMS_MAX) || ksem_dead) { 319 mtx_unlock(&ksem_count_lock); 320 return (NULL); 321 } 322 nsems++; 323 mtx_unlock(&ksem_count_lock); 324 ks = malloc(sizeof(*ks), M_KSEM, M_WAITOK | M_ZERO); 325 ks->ks_uid = ucred->cr_uid; 326 ks->ks_gid = ucred->cr_gid; 327 ks->ks_mode = mode; 328 ks->ks_value = value; 329 cv_init(&ks->ks_cv, "ksem"); 330 vfs_timestamp(&ks->ks_birthtime); 331 ks->ks_atime = ks->ks_mtime = ks->ks_ctime = ks->ks_birthtime; 332 refcount_init(&ks->ks_ref, 1); 333 #ifdef MAC 334 mac_posixsem_init(ks); 335 mac_posixsem_create(ucred, ks); 336 #endif 337 338 return (ks); 339 } 340 341 static struct ksem * 342 ksem_hold(struct ksem *ks) 343 { 344 345 refcount_acquire(&ks->ks_ref); 346 return (ks); 347 } 348 349 static void 350 ksem_drop(struct ksem *ks) 351 { 352 353 if (refcount_release(&ks->ks_ref)) { 354 #ifdef MAC 355 mac_posixsem_destroy(ks); 356 #endif 357 cv_destroy(&ks->ks_cv); 358 free(ks, M_KSEM); 359 mtx_lock(&ksem_count_lock); 360 nsems--; 361 mtx_unlock(&ksem_count_lock); 362 } 363 } 364 365 /* 366 * Determine if the credentials have sufficient permissions for read 367 * and write access. 368 */ 369 static int 370 ksem_access(struct ksem *ks, struct ucred *ucred) 371 { 372 int error; 373 374 error = vaccess(VREG, ks->ks_mode, ks->ks_uid, ks->ks_gid, 375 VREAD | VWRITE, ucred, NULL); 376 if (error) 377 error = priv_check_cred(ucred, PRIV_SEM_WRITE, 0); 378 return (error); 379 } 380 381 /* 382 * Dictionary management. We maintain an in-kernel dictionary to map 383 * paths to semaphore objects. We use the FNV hash on the path to 384 * store the mappings in a hash table. 385 */ 386 static struct ksem * 387 ksem_lookup(char *path, Fnv32_t fnv) 388 { 389 struct ksem_mapping *map; 390 391 LIST_FOREACH(map, KSEM_HASH(fnv), km_link) { 392 if (map->km_fnv != fnv) 393 continue; 394 if (strcmp(map->km_path, path) == 0) 395 return (map->km_ksem); 396 } 397 398 return (NULL); 399 } 400 401 static void 402 ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks) 403 { 404 struct ksem_mapping *map; 405 406 map = malloc(sizeof(struct ksem_mapping), M_KSEM, M_WAITOK); 407 map->km_path = path; 408 map->km_fnv = fnv; 409 map->km_ksem = ksem_hold(ks); 410 LIST_INSERT_HEAD(KSEM_HASH(fnv), map, km_link); 411 } 412 413 static int 414 ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 415 { 416 struct ksem_mapping *map; 417 int error; 418 419 LIST_FOREACH(map, KSEM_HASH(fnv), km_link) { 420 if (map->km_fnv != fnv) 421 continue; 422 if (strcmp(map->km_path, path) == 0) { 423 #ifdef MAC 424 error = mac_posixsem_check_unlink(ucred, map->km_ksem); 425 if (error) 426 return (error); 427 #endif 428 error = ksem_access(map->km_ksem, ucred); 429 if (error) 430 return (error); 431 LIST_REMOVE(map, km_link); 432 ksem_drop(map->km_ksem); 433 free(map->km_path, M_KSEM); 434 free(map, M_KSEM); 435 return (0); 436 } 437 } 438 439 return (ENOENT); 440 } 441 442 static int 443 ksem_create_copyout_semid(struct thread *td, semid_t *semidp, int fd, 444 int compat32) 445 { 446 semid_t semid; 447 #ifdef COMPAT_FREEBSD32 448 int32_t semid32; 449 #endif 450 void *ptr; 451 size_t ptrs; 452 453 #ifdef COMPAT_FREEBSD32 454 if (compat32) { 455 semid32 = fd; 456 ptr = &semid32; 457 ptrs = sizeof(semid32); 458 } else { 459 #endif 460 semid = fd; 461 ptr = &semid; 462 ptrs = sizeof(semid); 463 compat32 = 0; /* silence gcc */ 464 #ifdef COMPAT_FREEBSD32 465 } 466 #endif 467 468 return (copyout(ptr, semidp, ptrs)); 469 } 470 471 /* Other helper routines. */ 472 static int 473 ksem_create(struct thread *td, const char *name, semid_t *semidp, mode_t mode, 474 unsigned int value, int flags, int compat32) 475 { 476 struct filedesc *fdp; 477 struct ksem *ks; 478 struct file *fp; 479 char *path; 480 Fnv32_t fnv; 481 int error, fd; 482 483 if (value > SEM_VALUE_MAX) 484 return (EINVAL); 485 486 fdp = td->td_proc->p_fd; 487 mode = (mode & ~fdp->fd_cmask) & ACCESSPERMS; 488 error = falloc(td, &fp, &fd, O_CLOEXEC); 489 if (error) { 490 if (name == NULL) 491 error = ENOSPC; 492 return (error); 493 } 494 495 /* 496 * Go ahead and copyout the file descriptor now. This is a bit 497 * premature, but it is a lot easier to handle errors as opposed 498 * to later when we've possibly created a new semaphore, etc. 499 */ 500 error = ksem_create_copyout_semid(td, semidp, fd, compat32); 501 if (error) { 502 fdclose(fdp, fp, fd, td); 503 fdrop(fp, td); 504 return (error); 505 } 506 507 if (name == NULL) { 508 /* Create an anonymous semaphore. */ 509 ks = ksem_alloc(td->td_ucred, mode, value); 510 if (ks == NULL) 511 error = ENOSPC; 512 else 513 ks->ks_flags |= KS_ANONYMOUS; 514 } else { 515 path = malloc(MAXPATHLEN, M_KSEM, M_WAITOK); 516 error = copyinstr(name, path, MAXPATHLEN, NULL); 517 518 /* Require paths to start with a '/' character. */ 519 if (error == 0 && path[0] != '/') 520 error = EINVAL; 521 if (error) { 522 fdclose(fdp, fp, fd, td); 523 fdrop(fp, td); 524 free(path, M_KSEM); 525 return (error); 526 } 527 528 fnv = fnv_32_str(path, FNV1_32_INIT); 529 sx_xlock(&ksem_dict_lock); 530 ks = ksem_lookup(path, fnv); 531 if (ks == NULL) { 532 /* Object does not exist, create it if requested. */ 533 if (flags & O_CREAT) { 534 ks = ksem_alloc(td->td_ucred, mode, value); 535 if (ks == NULL) 536 error = ENFILE; 537 else { 538 ksem_insert(path, fnv, ks); 539 path = NULL; 540 } 541 } else 542 error = ENOENT; 543 } else { 544 /* 545 * Object already exists, obtain a new 546 * reference if requested and permitted. 547 */ 548 if ((flags & (O_CREAT | O_EXCL)) == 549 (O_CREAT | O_EXCL)) 550 error = EEXIST; 551 else { 552 #ifdef MAC 553 error = mac_posixsem_check_open(td->td_ucred, 554 ks); 555 if (error == 0) 556 #endif 557 error = ksem_access(ks, td->td_ucred); 558 } 559 if (error == 0) 560 ksem_hold(ks); 561 #ifdef INVARIANTS 562 else 563 ks = NULL; 564 #endif 565 } 566 sx_xunlock(&ksem_dict_lock); 567 if (path) 568 free(path, M_KSEM); 569 } 570 571 if (error) { 572 KASSERT(ks == NULL, ("ksem_create error with a ksem")); 573 fdclose(fdp, fp, fd, td); 574 fdrop(fp, td); 575 return (error); 576 } 577 KASSERT(ks != NULL, ("ksem_create w/o a ksem")); 578 579 finit(fp, FREAD | FWRITE, DTYPE_SEM, ks, &ksem_ops); 580 581 fdrop(fp, td); 582 583 return (0); 584 } 585 586 static int 587 ksem_get(struct thread *td, semid_t id, cap_rights_t rights, struct file **fpp) 588 { 589 struct ksem *ks; 590 struct file *fp; 591 int error; 592 593 error = fget(td, id, rights, &fp); 594 if (error) 595 return (EINVAL); 596 if (fp->f_type != DTYPE_SEM) { 597 fdrop(fp, td); 598 return (EINVAL); 599 } 600 ks = fp->f_data; 601 if (ks->ks_flags & KS_DEAD) { 602 fdrop(fp, td); 603 return (EINVAL); 604 } 605 *fpp = fp; 606 return (0); 607 } 608 609 /* System calls. */ 610 #ifndef _SYS_SYSPROTO_H_ 611 struct ksem_init_args { 612 unsigned int value; 613 semid_t *idp; 614 }; 615 #endif 616 int 617 sys_ksem_init(struct thread *td, struct ksem_init_args *uap) 618 { 619 620 return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value, 621 0, 0)); 622 } 623 624 #ifndef _SYS_SYSPROTO_H_ 625 struct ksem_open_args { 626 char *name; 627 int oflag; 628 mode_t mode; 629 unsigned int value; 630 semid_t *idp; 631 }; 632 #endif 633 int 634 sys_ksem_open(struct thread *td, struct ksem_open_args *uap) 635 { 636 637 DP((">>> ksem_open start, pid=%d\n", (int)td->td_proc->p_pid)); 638 639 if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0) 640 return (EINVAL); 641 return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value, 642 uap->oflag, 0)); 643 } 644 645 #ifndef _SYS_SYSPROTO_H_ 646 struct ksem_unlink_args { 647 char *name; 648 }; 649 #endif 650 int 651 sys_ksem_unlink(struct thread *td, struct ksem_unlink_args *uap) 652 { 653 char *path; 654 Fnv32_t fnv; 655 int error; 656 657 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 658 error = copyinstr(uap->name, path, MAXPATHLEN, NULL); 659 if (error) { 660 free(path, M_TEMP); 661 return (error); 662 } 663 664 fnv = fnv_32_str(path, FNV1_32_INIT); 665 sx_xlock(&ksem_dict_lock); 666 error = ksem_remove(path, fnv, td->td_ucred); 667 sx_xunlock(&ksem_dict_lock); 668 free(path, M_TEMP); 669 670 return (error); 671 } 672 673 #ifndef _SYS_SYSPROTO_H_ 674 struct ksem_close_args { 675 semid_t id; 676 }; 677 #endif 678 int 679 sys_ksem_close(struct thread *td, struct ksem_close_args *uap) 680 { 681 struct ksem *ks; 682 struct file *fp; 683 int error; 684 685 /* No capability rights required to close a semaphore. */ 686 error = ksem_get(td, uap->id, 0, &fp); 687 if (error) 688 return (error); 689 ks = fp->f_data; 690 if (ks->ks_flags & KS_ANONYMOUS) { 691 fdrop(fp, td); 692 return (EINVAL); 693 } 694 error = kern_close(td, uap->id); 695 fdrop(fp, td); 696 return (error); 697 } 698 699 #ifndef _SYS_SYSPROTO_H_ 700 struct ksem_post_args { 701 semid_t id; 702 }; 703 #endif 704 int 705 sys_ksem_post(struct thread *td, struct ksem_post_args *uap) 706 { 707 struct file *fp; 708 struct ksem *ks; 709 int error; 710 711 error = ksem_get(td, uap->id, CAP_SEM_POST, &fp); 712 if (error) 713 return (error); 714 ks = fp->f_data; 715 716 mtx_lock(&sem_lock); 717 #ifdef MAC 718 error = mac_posixsem_check_post(td->td_ucred, fp->f_cred, ks); 719 if (error) 720 goto err; 721 #endif 722 if (ks->ks_value == SEM_VALUE_MAX) { 723 error = EOVERFLOW; 724 goto err; 725 } 726 ++ks->ks_value; 727 if (ks->ks_waiters > 0) 728 cv_signal(&ks->ks_cv); 729 error = 0; 730 vfs_timestamp(&ks->ks_ctime); 731 err: 732 mtx_unlock(&sem_lock); 733 fdrop(fp, td); 734 return (error); 735 } 736 737 #ifndef _SYS_SYSPROTO_H_ 738 struct ksem_wait_args { 739 semid_t id; 740 }; 741 #endif 742 int 743 sys_ksem_wait(struct thread *td, struct ksem_wait_args *uap) 744 { 745 746 return (kern_sem_wait(td, uap->id, 0, NULL)); 747 } 748 749 #ifndef _SYS_SYSPROTO_H_ 750 struct ksem_timedwait_args { 751 semid_t id; 752 const struct timespec *abstime; 753 }; 754 #endif 755 int 756 sys_ksem_timedwait(struct thread *td, struct ksem_timedwait_args *uap) 757 { 758 struct timespec abstime; 759 struct timespec *ts; 760 int error; 761 762 /* 763 * We allow a null timespec (wait forever). 764 */ 765 if (uap->abstime == NULL) 766 ts = NULL; 767 else { 768 error = copyin(uap->abstime, &abstime, sizeof(abstime)); 769 if (error != 0) 770 return (error); 771 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0) 772 return (EINVAL); 773 ts = &abstime; 774 } 775 return (kern_sem_wait(td, uap->id, 0, ts)); 776 } 777 778 #ifndef _SYS_SYSPROTO_H_ 779 struct ksem_trywait_args { 780 semid_t id; 781 }; 782 #endif 783 int 784 sys_ksem_trywait(struct thread *td, struct ksem_trywait_args *uap) 785 { 786 787 return (kern_sem_wait(td, uap->id, 1, NULL)); 788 } 789 790 static int 791 kern_sem_wait(struct thread *td, semid_t id, int tryflag, 792 struct timespec *abstime) 793 { 794 struct timespec ts1, ts2; 795 struct timeval tv; 796 struct file *fp; 797 struct ksem *ks; 798 int error; 799 800 DP((">>> kern_sem_wait entered! pid=%d\n", (int)td->td_proc->p_pid)); 801 error = ksem_get(td, id, CAP_SEM_WAIT, &fp); 802 if (error) 803 return (error); 804 ks = fp->f_data; 805 mtx_lock(&sem_lock); 806 DP((">>> kern_sem_wait critical section entered! pid=%d\n", 807 (int)td->td_proc->p_pid)); 808 #ifdef MAC 809 error = mac_posixsem_check_wait(td->td_ucred, fp->f_cred, ks); 810 if (error) { 811 DP(("kern_sem_wait mac failed\n")); 812 goto err; 813 } 814 #endif 815 DP(("kern_sem_wait value = %d, tryflag %d\n", ks->ks_value, tryflag)); 816 vfs_timestamp(&ks->ks_atime); 817 while (ks->ks_value == 0) { 818 ks->ks_waiters++; 819 if (tryflag != 0) 820 error = EAGAIN; 821 else if (abstime == NULL) 822 error = cv_wait_sig(&ks->ks_cv, &sem_lock); 823 else { 824 for (;;) { 825 ts1 = *abstime; 826 getnanotime(&ts2); 827 timespecsub(&ts1, &ts2); 828 TIMESPEC_TO_TIMEVAL(&tv, &ts1); 829 if (tv.tv_sec < 0) { 830 error = ETIMEDOUT; 831 break; 832 } 833 error = cv_timedwait_sig(&ks->ks_cv, 834 &sem_lock, tvtohz(&tv)); 835 if (error != EWOULDBLOCK) 836 break; 837 } 838 } 839 ks->ks_waiters--; 840 if (error) 841 goto err; 842 } 843 ks->ks_value--; 844 DP(("kern_sem_wait value post-decrement = %d\n", ks->ks_value)); 845 error = 0; 846 err: 847 mtx_unlock(&sem_lock); 848 fdrop(fp, td); 849 if (error == ERESTART) 850 error = EINTR; 851 DP(("<<< kern_sem_wait leaving, pid=%d, error = %d\n", 852 (int)td->td_proc->p_pid, error)); 853 return (error); 854 } 855 856 #ifndef _SYS_SYSPROTO_H_ 857 struct ksem_getvalue_args { 858 semid_t id; 859 int *val; 860 }; 861 #endif 862 int 863 sys_ksem_getvalue(struct thread *td, struct ksem_getvalue_args *uap) 864 { 865 struct file *fp; 866 struct ksem *ks; 867 int error, val; 868 869 error = ksem_get(td, uap->id, CAP_SEM_GETVALUE, &fp); 870 if (error) 871 return (error); 872 ks = fp->f_data; 873 874 mtx_lock(&sem_lock); 875 #ifdef MAC 876 error = mac_posixsem_check_getvalue(td->td_ucred, fp->f_cred, ks); 877 if (error) { 878 mtx_unlock(&sem_lock); 879 fdrop(fp, td); 880 return (error); 881 } 882 #endif 883 val = ks->ks_value; 884 vfs_timestamp(&ks->ks_atime); 885 mtx_unlock(&sem_lock); 886 fdrop(fp, td); 887 error = copyout(&val, uap->val, sizeof(val)); 888 return (error); 889 } 890 891 #ifndef _SYS_SYSPROTO_H_ 892 struct ksem_destroy_args { 893 semid_t id; 894 }; 895 #endif 896 int 897 sys_ksem_destroy(struct thread *td, struct ksem_destroy_args *uap) 898 { 899 struct file *fp; 900 struct ksem *ks; 901 int error; 902 903 /* No capability rights required to close a semaphore. */ 904 error = ksem_get(td, uap->id, 0, &fp); 905 if (error) 906 return (error); 907 ks = fp->f_data; 908 if (!(ks->ks_flags & KS_ANONYMOUS)) { 909 fdrop(fp, td); 910 return (EINVAL); 911 } 912 mtx_lock(&sem_lock); 913 if (ks->ks_waiters != 0) { 914 mtx_unlock(&sem_lock); 915 error = EBUSY; 916 goto err; 917 } 918 ks->ks_flags |= KS_DEAD; 919 mtx_unlock(&sem_lock); 920 921 error = kern_close(td, uap->id); 922 err: 923 fdrop(fp, td); 924 return (error); 925 } 926 927 static struct syscall_helper_data ksem_syscalls[] = { 928 SYSCALL_INIT_HELPER(ksem_init), 929 SYSCALL_INIT_HELPER(ksem_open), 930 SYSCALL_INIT_HELPER(ksem_unlink), 931 SYSCALL_INIT_HELPER(ksem_close), 932 SYSCALL_INIT_HELPER(ksem_post), 933 SYSCALL_INIT_HELPER(ksem_wait), 934 SYSCALL_INIT_HELPER(ksem_timedwait), 935 SYSCALL_INIT_HELPER(ksem_trywait), 936 SYSCALL_INIT_HELPER(ksem_getvalue), 937 SYSCALL_INIT_HELPER(ksem_destroy), 938 SYSCALL_INIT_LAST 939 }; 940 941 #ifdef COMPAT_FREEBSD32 942 #include <compat/freebsd32/freebsd32.h> 943 #include <compat/freebsd32/freebsd32_proto.h> 944 #include <compat/freebsd32/freebsd32_signal.h> 945 #include <compat/freebsd32/freebsd32_syscall.h> 946 #include <compat/freebsd32/freebsd32_util.h> 947 948 int 949 freebsd32_ksem_init(struct thread *td, struct freebsd32_ksem_init_args *uap) 950 { 951 952 return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value, 953 0, 1)); 954 } 955 956 int 957 freebsd32_ksem_open(struct thread *td, struct freebsd32_ksem_open_args *uap) 958 { 959 960 if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0) 961 return (EINVAL); 962 return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value, 963 uap->oflag, 1)); 964 } 965 966 int 967 freebsd32_ksem_timedwait(struct thread *td, 968 struct freebsd32_ksem_timedwait_args *uap) 969 { 970 struct timespec32 abstime32; 971 struct timespec *ts, abstime; 972 int error; 973 974 /* 975 * We allow a null timespec (wait forever). 976 */ 977 if (uap->abstime == NULL) 978 ts = NULL; 979 else { 980 error = copyin(uap->abstime, &abstime32, sizeof(abstime32)); 981 if (error != 0) 982 return (error); 983 CP(abstime32, abstime, tv_sec); 984 CP(abstime32, abstime, tv_nsec); 985 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0) 986 return (EINVAL); 987 ts = &abstime; 988 } 989 return (kern_sem_wait(td, uap->id, 0, ts)); 990 } 991 992 static struct syscall_helper_data ksem32_syscalls[] = { 993 SYSCALL32_INIT_HELPER(freebsd32_ksem_init), 994 SYSCALL32_INIT_HELPER(freebsd32_ksem_open), 995 SYSCALL32_INIT_HELPER_COMPAT(ksem_unlink), 996 SYSCALL32_INIT_HELPER_COMPAT(ksem_close), 997 SYSCALL32_INIT_HELPER_COMPAT(ksem_post), 998 SYSCALL32_INIT_HELPER_COMPAT(ksem_wait), 999 SYSCALL32_INIT_HELPER(freebsd32_ksem_timedwait), 1000 SYSCALL32_INIT_HELPER_COMPAT(ksem_trywait), 1001 SYSCALL32_INIT_HELPER_COMPAT(ksem_getvalue), 1002 SYSCALL32_INIT_HELPER_COMPAT(ksem_destroy), 1003 SYSCALL_INIT_LAST 1004 }; 1005 #endif 1006 1007 static int 1008 ksem_module_init(void) 1009 { 1010 int error; 1011 1012 mtx_init(&sem_lock, "sem", NULL, MTX_DEF); 1013 mtx_init(&ksem_count_lock, "ksem count", NULL, MTX_DEF); 1014 sx_init(&ksem_dict_lock, "ksem dictionary"); 1015 ksem_dictionary = hashinit(1024, M_KSEM, &ksem_hash); 1016 p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 200112L); 1017 p31b_setcfg(CTL_P1003_1B_SEM_NSEMS_MAX, SEM_MAX); 1018 p31b_setcfg(CTL_P1003_1B_SEM_VALUE_MAX, SEM_VALUE_MAX); 1019 1020 error = syscall_helper_register(ksem_syscalls); 1021 if (error) 1022 return (error); 1023 #ifdef COMPAT_FREEBSD32 1024 error = syscall32_helper_register(ksem32_syscalls); 1025 if (error) 1026 return (error); 1027 #endif 1028 return (0); 1029 } 1030 1031 static void 1032 ksem_module_destroy(void) 1033 { 1034 1035 #ifdef COMPAT_FREEBSD32 1036 syscall32_helper_unregister(ksem32_syscalls); 1037 #endif 1038 syscall_helper_unregister(ksem_syscalls); 1039 1040 p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 0); 1041 hashdestroy(ksem_dictionary, M_KSEM, ksem_hash); 1042 sx_destroy(&ksem_dict_lock); 1043 mtx_destroy(&ksem_count_lock); 1044 mtx_destroy(&sem_lock); 1045 p31b_unsetcfg(CTL_P1003_1B_SEM_VALUE_MAX); 1046 p31b_unsetcfg(CTL_P1003_1B_SEM_NSEMS_MAX); 1047 } 1048 1049 static int 1050 sem_modload(struct module *module, int cmd, void *arg) 1051 { 1052 int error = 0; 1053 1054 switch (cmd) { 1055 case MOD_LOAD: 1056 error = ksem_module_init(); 1057 if (error) 1058 ksem_module_destroy(); 1059 break; 1060 1061 case MOD_UNLOAD: 1062 mtx_lock(&ksem_count_lock); 1063 if (nsems != 0) { 1064 error = EOPNOTSUPP; 1065 mtx_unlock(&ksem_count_lock); 1066 break; 1067 } 1068 ksem_dead = 1; 1069 mtx_unlock(&ksem_count_lock); 1070 ksem_module_destroy(); 1071 break; 1072 1073 case MOD_SHUTDOWN: 1074 break; 1075 default: 1076 error = EINVAL; 1077 break; 1078 } 1079 return (error); 1080 } 1081 1082 static moduledata_t sem_mod = { 1083 "sem", 1084 &sem_modload, 1085 NULL 1086 }; 1087 1088 DECLARE_MODULE(sem, sem_mod, SI_SUB_SYSV_SEM, SI_ORDER_FIRST); 1089 MODULE_VERSION(sem, 1); 1090