uipc_sem.c revision 321020
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: stable/10/sys/kern/uipc_sem.c 321020 2017-07-15 17:25:40Z dchagin $"); 36 37#include "opt_compat.h" 38#include "opt_posix.h" 39 40#include <sys/param.h> 41#include <sys/capsicum.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 69FEATURE(p1003_1b_semaphores, "POSIX P1003.1B semaphores support"); 70/* 71 * TODO 72 * 73 * - Resource limits? 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 88struct 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 95static MALLOC_DEFINE(M_KSEM, "ksem", "semaphore file descriptor"); 96static LIST_HEAD(, ksem_mapping) *ksem_dictionary; 97static struct sx ksem_dict_lock; 98static struct mtx ksem_count_lock; 99static struct mtx sem_lock; 100static u_long ksem_hash; 101static int ksem_dead; 102 103#define KSEM_HASH(fnv) (&ksem_dictionary[(fnv) & ksem_hash]) 104 105static int nsems = 0; 106SYSCTL_DECL(_p1003_1b); 107SYSCTL_INT(_p1003_1b, OID_AUTO, nsems, CTLFLAG_RD, &nsems, 0, 108 "Number of active kernel POSIX semaphores"); 109 110static int kern_sem_wait(struct thread *td, semid_t id, int tryflag, 111 struct timespec *abstime); 112static int ksem_access(struct ksem *ks, struct ucred *ucred); 113static struct ksem *ksem_alloc(struct ucred *ucred, mode_t mode, 114 unsigned int value); 115static int ksem_create(struct thread *td, const char *path, 116 semid_t *semidp, mode_t mode, unsigned int value, 117 int flags, int compat32); 118static void ksem_drop(struct ksem *ks); 119static int ksem_get(struct thread *td, semid_t id, cap_rights_t *rightsp, 120 struct file **fpp); 121static struct ksem *ksem_hold(struct ksem *ks); 122static void ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks); 123static struct ksem *ksem_lookup(char *path, Fnv32_t fnv); 124static void ksem_module_destroy(void); 125static int ksem_module_init(void); 126static int ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred); 127static int sem_modload(struct module *module, int cmd, void *arg); 128 129static fo_rdwr_t ksem_read; 130static fo_rdwr_t ksem_write; 131static fo_truncate_t ksem_truncate; 132static fo_ioctl_t ksem_ioctl; 133static fo_poll_t ksem_poll; 134static fo_kqfilter_t ksem_kqfilter; 135static fo_stat_t ksem_stat; 136static fo_close_t ksem_closef; 137static fo_chmod_t ksem_chmod; 138static fo_chown_t ksem_chown; 139 140/* File descriptor operations. */ 141static struct fileops ksem_ops = { 142 .fo_read = ksem_read, 143 .fo_write = ksem_write, 144 .fo_truncate = ksem_truncate, 145 .fo_ioctl = ksem_ioctl, 146 .fo_poll = ksem_poll, 147 .fo_kqfilter = ksem_kqfilter, 148 .fo_stat = ksem_stat, 149 .fo_close = ksem_closef, 150 .fo_chmod = ksem_chmod, 151 .fo_chown = ksem_chown, 152 .fo_sendfile = invfo_sendfile, 153 .fo_flags = DFLAG_PASSABLE 154}; 155 156FEATURE(posix_sem, "POSIX semaphores"); 157 158static int 159ksem_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 160 int flags, struct thread *td) 161{ 162 163 return (EOPNOTSUPP); 164} 165 166static int 167ksem_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 168 int flags, struct thread *td) 169{ 170 171 return (EOPNOTSUPP); 172} 173 174static int 175ksem_truncate(struct file *fp, off_t length, struct ucred *active_cred, 176 struct thread *td) 177{ 178 179 return (EINVAL); 180} 181 182static int 183ksem_ioctl(struct file *fp, u_long com, void *data, 184 struct ucred *active_cred, struct thread *td) 185{ 186 187 return (EOPNOTSUPP); 188} 189 190static int 191ksem_poll(struct file *fp, int events, struct ucred *active_cred, 192 struct thread *td) 193{ 194 195 return (EOPNOTSUPP); 196} 197 198static int 199ksem_kqfilter(struct file *fp, struct knote *kn) 200{ 201 202 return (EOPNOTSUPP); 203} 204 205static int 206ksem_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 241static int 242ksem_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; 261out: 262 mtx_unlock(&sem_lock); 263 return (error); 264} 265 266static int 267ksem_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; 291out: 292 mtx_unlock(&sem_lock); 293 return (error); 294} 295 296static int 297ksem_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 */ 312static struct ksem * 313ksem_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 341static struct ksem * 342ksem_hold(struct ksem *ks) 343{ 344 345 refcount_acquire(&ks->ks_ref); 346 return (ks); 347} 348 349static void 350ksem_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 */ 369static int 370ksem_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 */ 386static struct ksem * 387ksem_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 401static void 402ksem_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 ks->ks_path = path; 411 LIST_INSERT_HEAD(KSEM_HASH(fnv), map, km_link); 412} 413 414static int 415ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 416{ 417 struct ksem_mapping *map; 418 int error; 419 420 LIST_FOREACH(map, KSEM_HASH(fnv), km_link) { 421 if (map->km_fnv != fnv) 422 continue; 423 if (strcmp(map->km_path, path) == 0) { 424#ifdef MAC 425 error = mac_posixsem_check_unlink(ucred, map->km_ksem); 426 if (error) 427 return (error); 428#endif 429 error = ksem_access(map->km_ksem, ucred); 430 if (error) 431 return (error); 432 map->km_ksem->ks_path = NULL; 433 LIST_REMOVE(map, km_link); 434 ksem_drop(map->km_ksem); 435 free(map->km_path, M_KSEM); 436 free(map, M_KSEM); 437 return (0); 438 } 439 } 440 441 return (ENOENT); 442} 443 444static void 445ksem_info_impl(struct ksem *ks, char *path, size_t size, uint32_t *value) 446{ 447 448 if (ks->ks_path == NULL) 449 return; 450 sx_slock(&ksem_dict_lock); 451 if (ks->ks_path != NULL) 452 strlcpy(path, ks->ks_path, size); 453 if (value != NULL) 454 *value = ks->ks_value; 455 sx_sunlock(&ksem_dict_lock); 456} 457 458static int 459ksem_create_copyout_semid(struct thread *td, semid_t *semidp, int fd, 460 int compat32) 461{ 462 semid_t semid; 463#ifdef COMPAT_FREEBSD32 464 int32_t semid32; 465#endif 466 void *ptr; 467 size_t ptrs; 468 469#ifdef COMPAT_FREEBSD32 470 if (compat32) { 471 semid32 = fd; 472 ptr = &semid32; 473 ptrs = sizeof(semid32); 474 } else { 475#endif 476 semid = fd; 477 ptr = &semid; 478 ptrs = sizeof(semid); 479 compat32 = 0; /* silence gcc */ 480#ifdef COMPAT_FREEBSD32 481 } 482#endif 483 484 return (copyout(ptr, semidp, ptrs)); 485} 486 487/* Other helper routines. */ 488static int 489ksem_create(struct thread *td, const char *name, semid_t *semidp, mode_t mode, 490 unsigned int value, int flags, int compat32) 491{ 492 struct filedesc *fdp; 493 struct ksem *ks; 494 struct file *fp; 495 char *path; 496 Fnv32_t fnv; 497 int error, fd; 498 499 if (value > SEM_VALUE_MAX) 500 return (EINVAL); 501 502 fdp = td->td_proc->p_fd; 503 mode = (mode & ~fdp->fd_cmask) & ACCESSPERMS; 504 error = falloc(td, &fp, &fd, O_CLOEXEC); 505 if (error) { 506 if (name == NULL) 507 error = ENOSPC; 508 return (error); 509 } 510 511 /* 512 * Go ahead and copyout the file descriptor now. This is a bit 513 * premature, but it is a lot easier to handle errors as opposed 514 * to later when we've possibly created a new semaphore, etc. 515 */ 516 error = ksem_create_copyout_semid(td, semidp, fd, compat32); 517 if (error) { 518 fdclose(td, fp, fd); 519 fdrop(fp, td); 520 return (error); 521 } 522 523 if (name == NULL) { 524 /* Create an anonymous semaphore. */ 525 ks = ksem_alloc(td->td_ucred, mode, value); 526 if (ks == NULL) 527 error = ENOSPC; 528 else 529 ks->ks_flags |= KS_ANONYMOUS; 530 } else { 531 path = malloc(MAXPATHLEN, M_KSEM, M_WAITOK); 532 error = copyinstr(name, path, MAXPATHLEN, NULL); 533 534 /* Require paths to start with a '/' character. */ 535 if (error == 0 && path[0] != '/') 536 error = EINVAL; 537 if (error) { 538 fdclose(td, fp, fd); 539 fdrop(fp, td); 540 free(path, M_KSEM); 541 return (error); 542 } 543 544 fnv = fnv_32_str(path, FNV1_32_INIT); 545 sx_xlock(&ksem_dict_lock); 546 ks = ksem_lookup(path, fnv); 547 if (ks == NULL) { 548 /* Object does not exist, create it if requested. */ 549 if (flags & O_CREAT) { 550 ks = ksem_alloc(td->td_ucred, mode, value); 551 if (ks == NULL) 552 error = ENFILE; 553 else { 554 ksem_insert(path, fnv, ks); 555 path = NULL; 556 } 557 } else 558 error = ENOENT; 559 } else { 560 /* 561 * Object already exists, obtain a new 562 * reference if requested and permitted. 563 */ 564 if ((flags & (O_CREAT | O_EXCL)) == 565 (O_CREAT | O_EXCL)) 566 error = EEXIST; 567 else { 568#ifdef MAC 569 error = mac_posixsem_check_open(td->td_ucred, 570 ks); 571 if (error == 0) 572#endif 573 error = ksem_access(ks, td->td_ucred); 574 } 575 if (error == 0) 576 ksem_hold(ks); 577#ifdef INVARIANTS 578 else 579 ks = NULL; 580#endif 581 } 582 sx_xunlock(&ksem_dict_lock); 583 if (path) 584 free(path, M_KSEM); 585 } 586 587 if (error) { 588 KASSERT(ks == NULL, ("ksem_create error with a ksem")); 589 fdclose(td, fp, fd); 590 fdrop(fp, td); 591 return (error); 592 } 593 KASSERT(ks != NULL, ("ksem_create w/o a ksem")); 594 595 finit(fp, FREAD | FWRITE, DTYPE_SEM, ks, &ksem_ops); 596 597 fdrop(fp, td); 598 599 return (0); 600} 601 602static int 603ksem_get(struct thread *td, semid_t id, cap_rights_t *rightsp, 604 struct file **fpp) 605{ 606 struct ksem *ks; 607 struct file *fp; 608 int error; 609 610 error = fget(td, id, rightsp, &fp); 611 if (error) 612 return (EINVAL); 613 if (fp->f_type != DTYPE_SEM) { 614 fdrop(fp, td); 615 return (EINVAL); 616 } 617 ks = fp->f_data; 618 if (ks->ks_flags & KS_DEAD) { 619 fdrop(fp, td); 620 return (EINVAL); 621 } 622 *fpp = fp; 623 return (0); 624} 625 626/* System calls. */ 627#ifndef _SYS_SYSPROTO_H_ 628struct ksem_init_args { 629 unsigned int value; 630 semid_t *idp; 631}; 632#endif 633int 634sys_ksem_init(struct thread *td, struct ksem_init_args *uap) 635{ 636 637 return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value, 638 0, 0)); 639} 640 641#ifndef _SYS_SYSPROTO_H_ 642struct ksem_open_args { 643 char *name; 644 int oflag; 645 mode_t mode; 646 unsigned int value; 647 semid_t *idp; 648}; 649#endif 650int 651sys_ksem_open(struct thread *td, struct ksem_open_args *uap) 652{ 653 654 DP((">>> ksem_open start, pid=%d\n", (int)td->td_proc->p_pid)); 655 656 if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0) 657 return (EINVAL); 658 return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value, 659 uap->oflag, 0)); 660} 661 662#ifndef _SYS_SYSPROTO_H_ 663struct ksem_unlink_args { 664 char *name; 665}; 666#endif 667int 668sys_ksem_unlink(struct thread *td, struct ksem_unlink_args *uap) 669{ 670 char *path; 671 Fnv32_t fnv; 672 int error; 673 674 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 675 error = copyinstr(uap->name, path, MAXPATHLEN, NULL); 676 if (error) { 677 free(path, M_TEMP); 678 return (error); 679 } 680 681 fnv = fnv_32_str(path, FNV1_32_INIT); 682 sx_xlock(&ksem_dict_lock); 683 error = ksem_remove(path, fnv, td->td_ucred); 684 sx_xunlock(&ksem_dict_lock); 685 free(path, M_TEMP); 686 687 return (error); 688} 689 690#ifndef _SYS_SYSPROTO_H_ 691struct ksem_close_args { 692 semid_t id; 693}; 694#endif 695int 696sys_ksem_close(struct thread *td, struct ksem_close_args *uap) 697{ 698 struct ksem *ks; 699 struct file *fp; 700 int error; 701 702 /* No capability rights required to close a semaphore. */ 703 error = ksem_get(td, uap->id, 0, &fp); 704 if (error) 705 return (error); 706 ks = fp->f_data; 707 if (ks->ks_flags & KS_ANONYMOUS) { 708 fdrop(fp, td); 709 return (EINVAL); 710 } 711 error = kern_close(td, uap->id); 712 fdrop(fp, td); 713 return (error); 714} 715 716#ifndef _SYS_SYSPROTO_H_ 717struct ksem_post_args { 718 semid_t id; 719}; 720#endif 721int 722sys_ksem_post(struct thread *td, struct ksem_post_args *uap) 723{ 724 cap_rights_t rights; 725 struct file *fp; 726 struct ksem *ks; 727 int error; 728 729 error = ksem_get(td, uap->id, 730 cap_rights_init(&rights, CAP_SEM_POST), &fp); 731 if (error) 732 return (error); 733 ks = fp->f_data; 734 735 mtx_lock(&sem_lock); 736#ifdef MAC 737 error = mac_posixsem_check_post(td->td_ucred, fp->f_cred, ks); 738 if (error) 739 goto err; 740#endif 741 if (ks->ks_value == SEM_VALUE_MAX) { 742 error = EOVERFLOW; 743 goto err; 744 } 745 ++ks->ks_value; 746 if (ks->ks_waiters > 0) 747 cv_signal(&ks->ks_cv); 748 error = 0; 749 vfs_timestamp(&ks->ks_ctime); 750err: 751 mtx_unlock(&sem_lock); 752 fdrop(fp, td); 753 return (error); 754} 755 756#ifndef _SYS_SYSPROTO_H_ 757struct ksem_wait_args { 758 semid_t id; 759}; 760#endif 761int 762sys_ksem_wait(struct thread *td, struct ksem_wait_args *uap) 763{ 764 765 return (kern_sem_wait(td, uap->id, 0, NULL)); 766} 767 768#ifndef _SYS_SYSPROTO_H_ 769struct ksem_timedwait_args { 770 semid_t id; 771 const struct timespec *abstime; 772}; 773#endif 774int 775sys_ksem_timedwait(struct thread *td, struct ksem_timedwait_args *uap) 776{ 777 struct timespec abstime; 778 struct timespec *ts; 779 int error; 780 781 /* 782 * We allow a null timespec (wait forever). 783 */ 784 if (uap->abstime == NULL) 785 ts = NULL; 786 else { 787 error = copyin(uap->abstime, &abstime, sizeof(abstime)); 788 if (error != 0) 789 return (error); 790 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0) 791 return (EINVAL); 792 ts = &abstime; 793 } 794 return (kern_sem_wait(td, uap->id, 0, ts)); 795} 796 797#ifndef _SYS_SYSPROTO_H_ 798struct ksem_trywait_args { 799 semid_t id; 800}; 801#endif 802int 803sys_ksem_trywait(struct thread *td, struct ksem_trywait_args *uap) 804{ 805 806 return (kern_sem_wait(td, uap->id, 1, NULL)); 807} 808 809static int 810kern_sem_wait(struct thread *td, semid_t id, int tryflag, 811 struct timespec *abstime) 812{ 813 struct timespec ts1, ts2; 814 struct timeval tv; 815 cap_rights_t rights; 816 struct file *fp; 817 struct ksem *ks; 818 int error; 819 820 DP((">>> kern_sem_wait entered! pid=%d\n", (int)td->td_proc->p_pid)); 821 error = ksem_get(td, id, cap_rights_init(&rights, CAP_SEM_WAIT), &fp); 822 if (error) 823 return (error); 824 ks = fp->f_data; 825 mtx_lock(&sem_lock); 826 DP((">>> kern_sem_wait critical section entered! pid=%d\n", 827 (int)td->td_proc->p_pid)); 828#ifdef MAC 829 error = mac_posixsem_check_wait(td->td_ucred, fp->f_cred, ks); 830 if (error) { 831 DP(("kern_sem_wait mac failed\n")); 832 goto err; 833 } 834#endif 835 DP(("kern_sem_wait value = %d, tryflag %d\n", ks->ks_value, tryflag)); 836 vfs_timestamp(&ks->ks_atime); 837 while (ks->ks_value == 0) { 838 ks->ks_waiters++; 839 if (tryflag != 0) 840 error = EAGAIN; 841 else if (abstime == NULL) 842 error = cv_wait_sig(&ks->ks_cv, &sem_lock); 843 else { 844 for (;;) { 845 ts1 = *abstime; 846 getnanotime(&ts2); 847 timespecsub(&ts1, &ts2); 848 TIMESPEC_TO_TIMEVAL(&tv, &ts1); 849 if (tv.tv_sec < 0) { 850 error = ETIMEDOUT; 851 break; 852 } 853 error = cv_timedwait_sig(&ks->ks_cv, 854 &sem_lock, tvtohz(&tv)); 855 if (error != EWOULDBLOCK) 856 break; 857 } 858 } 859 ks->ks_waiters--; 860 if (error) 861 goto err; 862 } 863 ks->ks_value--; 864 DP(("kern_sem_wait value post-decrement = %d\n", ks->ks_value)); 865 error = 0; 866err: 867 mtx_unlock(&sem_lock); 868 fdrop(fp, td); 869 DP(("<<< kern_sem_wait leaving, pid=%d, error = %d\n", 870 (int)td->td_proc->p_pid, error)); 871 return (error); 872} 873 874#ifndef _SYS_SYSPROTO_H_ 875struct ksem_getvalue_args { 876 semid_t id; 877 int *val; 878}; 879#endif 880int 881sys_ksem_getvalue(struct thread *td, struct ksem_getvalue_args *uap) 882{ 883 cap_rights_t rights; 884 struct file *fp; 885 struct ksem *ks; 886 int error, val; 887 888 error = ksem_get(td, uap->id, 889 cap_rights_init(&rights, CAP_SEM_GETVALUE), &fp); 890 if (error) 891 return (error); 892 ks = fp->f_data; 893 894 mtx_lock(&sem_lock); 895#ifdef MAC 896 error = mac_posixsem_check_getvalue(td->td_ucred, fp->f_cred, ks); 897 if (error) { 898 mtx_unlock(&sem_lock); 899 fdrop(fp, td); 900 return (error); 901 } 902#endif 903 val = ks->ks_value; 904 vfs_timestamp(&ks->ks_atime); 905 mtx_unlock(&sem_lock); 906 fdrop(fp, td); 907 error = copyout(&val, uap->val, sizeof(val)); 908 return (error); 909} 910 911#ifndef _SYS_SYSPROTO_H_ 912struct ksem_destroy_args { 913 semid_t id; 914}; 915#endif 916int 917sys_ksem_destroy(struct thread *td, struct ksem_destroy_args *uap) 918{ 919 struct file *fp; 920 struct ksem *ks; 921 int error; 922 923 /* No capability rights required to close a semaphore. */ 924 error = ksem_get(td, uap->id, 0, &fp); 925 if (error) 926 return (error); 927 ks = fp->f_data; 928 if (!(ks->ks_flags & KS_ANONYMOUS)) { 929 fdrop(fp, td); 930 return (EINVAL); 931 } 932 mtx_lock(&sem_lock); 933 if (ks->ks_waiters != 0) { 934 mtx_unlock(&sem_lock); 935 error = EBUSY; 936 goto err; 937 } 938 ks->ks_flags |= KS_DEAD; 939 mtx_unlock(&sem_lock); 940 941 error = kern_close(td, uap->id); 942err: 943 fdrop(fp, td); 944 return (error); 945} 946 947static struct syscall_helper_data ksem_syscalls[] = { 948 SYSCALL_INIT_HELPER(ksem_init), 949 SYSCALL_INIT_HELPER(ksem_open), 950 SYSCALL_INIT_HELPER(ksem_unlink), 951 SYSCALL_INIT_HELPER(ksem_close), 952 SYSCALL_INIT_HELPER(ksem_post), 953 SYSCALL_INIT_HELPER(ksem_wait), 954 SYSCALL_INIT_HELPER(ksem_timedwait), 955 SYSCALL_INIT_HELPER(ksem_trywait), 956 SYSCALL_INIT_HELPER(ksem_getvalue), 957 SYSCALL_INIT_HELPER(ksem_destroy), 958 SYSCALL_INIT_LAST 959}; 960 961#ifdef COMPAT_FREEBSD32 962#include <compat/freebsd32/freebsd32.h> 963#include <compat/freebsd32/freebsd32_proto.h> 964#include <compat/freebsd32/freebsd32_signal.h> 965#include <compat/freebsd32/freebsd32_syscall.h> 966#include <compat/freebsd32/freebsd32_util.h> 967 968int 969freebsd32_ksem_init(struct thread *td, struct freebsd32_ksem_init_args *uap) 970{ 971 972 return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value, 973 0, 1)); 974} 975 976int 977freebsd32_ksem_open(struct thread *td, struct freebsd32_ksem_open_args *uap) 978{ 979 980 if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0) 981 return (EINVAL); 982 return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value, 983 uap->oflag, 1)); 984} 985 986int 987freebsd32_ksem_timedwait(struct thread *td, 988 struct freebsd32_ksem_timedwait_args *uap) 989{ 990 struct timespec32 abstime32; 991 struct timespec *ts, abstime; 992 int error; 993 994 /* 995 * We allow a null timespec (wait forever). 996 */ 997 if (uap->abstime == NULL) 998 ts = NULL; 999 else { 1000 error = copyin(uap->abstime, &abstime32, sizeof(abstime32)); 1001 if (error != 0) 1002 return (error); 1003 CP(abstime32, abstime, tv_sec); 1004 CP(abstime32, abstime, tv_nsec); 1005 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0) 1006 return (EINVAL); 1007 ts = &abstime; 1008 } 1009 return (kern_sem_wait(td, uap->id, 0, ts)); 1010} 1011 1012static struct syscall_helper_data ksem32_syscalls[] = { 1013 SYSCALL32_INIT_HELPER(freebsd32_ksem_init), 1014 SYSCALL32_INIT_HELPER(freebsd32_ksem_open), 1015 SYSCALL32_INIT_HELPER_COMPAT(ksem_unlink), 1016 SYSCALL32_INIT_HELPER_COMPAT(ksem_close), 1017 SYSCALL32_INIT_HELPER_COMPAT(ksem_post), 1018 SYSCALL32_INIT_HELPER_COMPAT(ksem_wait), 1019 SYSCALL32_INIT_HELPER(freebsd32_ksem_timedwait), 1020 SYSCALL32_INIT_HELPER_COMPAT(ksem_trywait), 1021 SYSCALL32_INIT_HELPER_COMPAT(ksem_getvalue), 1022 SYSCALL32_INIT_HELPER_COMPAT(ksem_destroy), 1023 SYSCALL_INIT_LAST 1024}; 1025#endif 1026 1027static int 1028ksem_module_init(void) 1029{ 1030 int error; 1031 1032 mtx_init(&sem_lock, "sem", NULL, MTX_DEF); 1033 mtx_init(&ksem_count_lock, "ksem count", NULL, MTX_DEF); 1034 sx_init(&ksem_dict_lock, "ksem dictionary"); 1035 ksem_dictionary = hashinit(1024, M_KSEM, &ksem_hash); 1036 p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 200112L); 1037 p31b_setcfg(CTL_P1003_1B_SEM_NSEMS_MAX, SEM_MAX); 1038 p31b_setcfg(CTL_P1003_1B_SEM_VALUE_MAX, SEM_VALUE_MAX); 1039 ksem_info = ksem_info_impl; 1040 1041 error = syscall_helper_register(ksem_syscalls); 1042 if (error) 1043 return (error); 1044#ifdef COMPAT_FREEBSD32 1045 error = syscall32_helper_register(ksem32_syscalls); 1046 if (error) 1047 return (error); 1048#endif 1049 return (0); 1050} 1051 1052static void 1053ksem_module_destroy(void) 1054{ 1055 1056#ifdef COMPAT_FREEBSD32 1057 syscall32_helper_unregister(ksem32_syscalls); 1058#endif 1059 syscall_helper_unregister(ksem_syscalls); 1060 1061 ksem_info = NULL; 1062 p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 0); 1063 hashdestroy(ksem_dictionary, M_KSEM, ksem_hash); 1064 sx_destroy(&ksem_dict_lock); 1065 mtx_destroy(&ksem_count_lock); 1066 mtx_destroy(&sem_lock); 1067 p31b_unsetcfg(CTL_P1003_1B_SEM_VALUE_MAX); 1068 p31b_unsetcfg(CTL_P1003_1B_SEM_NSEMS_MAX); 1069} 1070 1071static int 1072sem_modload(struct module *module, int cmd, void *arg) 1073{ 1074 int error = 0; 1075 1076 switch (cmd) { 1077 case MOD_LOAD: 1078 error = ksem_module_init(); 1079 if (error) 1080 ksem_module_destroy(); 1081 break; 1082 1083 case MOD_UNLOAD: 1084 mtx_lock(&ksem_count_lock); 1085 if (nsems != 0) { 1086 error = EOPNOTSUPP; 1087 mtx_unlock(&ksem_count_lock); 1088 break; 1089 } 1090 ksem_dead = 1; 1091 mtx_unlock(&ksem_count_lock); 1092 ksem_module_destroy(); 1093 break; 1094 1095 case MOD_SHUTDOWN: 1096 break; 1097 default: 1098 error = EINVAL; 1099 break; 1100 } 1101 return (error); 1102} 1103 1104static moduledata_t sem_mod = { 1105 "sem", 1106 &sem_modload, 1107 NULL 1108}; 1109 1110DECLARE_MODULE(sem, sem_mod, SI_SUB_SYSV_SEM, SI_ORDER_FIRST); 1111MODULE_VERSION(sem, 1); 1112