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FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_sem.c
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1 /*- 2 * Copyright (c) 2002 Alfred Perlstein <alfred@FreeBSD.org> 3 * Copyright (c) 2003-2005 SPARTA, Inc. 4 * Copyright (c) 2005 Robert N. M. Watson 5 * All rights reserved. 6 * 7 * This software was developed for the FreeBSD Project in part by Network 8 * Associates Laboratories, the Security Research Division of Network 9 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), 10 * as part of the DARPA CHATS research program. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #include <sys/cdefs.h> 35 __FBSDID("$FreeBSD: releng/11.0/sys/kern/uipc_sem.c 297976 2016-04-14 17:07:26Z jamie $"); 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/jail.h> 48 #include <sys/kernel.h> 49 #include <sys/ksem.h> 50 #include <sys/lock.h> 51 #include <sys/malloc.h> 52 #include <sys/module.h> 53 #include <sys/mutex.h> 54 #include <sys/priv.h> 55 #include <sys/proc.h> 56 #include <sys/posix4.h> 57 #include <sys/_semaphore.h> 58 #include <sys/stat.h> 59 #include <sys/syscall.h> 60 #include <sys/syscallsubr.h> 61 #include <sys/sysctl.h> 62 #include <sys/sysent.h> 63 #include <sys/sysproto.h> 64 #include <sys/systm.h> 65 #include <sys/sx.h> 66 #include <sys/user.h> 67 #include <sys/vnode.h> 68 69 #include <security/mac/mac_framework.h> 70 71 FEATURE(p1003_1b_semaphores, "POSIX P1003.1B semaphores support"); 72 /* 73 * TODO 74 * 75 * - Resource limits? 76 * - Replace global sem_lock with mtx_pool locks? 77 * - Add a MAC check_create() hook for creating new named semaphores. 78 */ 79 80 #ifndef SEM_MAX 81 #define SEM_MAX 30 82 #endif 83 84 #ifdef SEM_DEBUG 85 #define DP(x) printf x 86 #else 87 #define DP(x) 88 #endif 89 90 struct ksem_mapping { 91 char *km_path; 92 Fnv32_t km_fnv; 93 struct ksem *km_ksem; 94 LIST_ENTRY(ksem_mapping) km_link; 95 }; 96 97 static MALLOC_DEFINE(M_KSEM, "ksem", "semaphore file descriptor"); 98 static LIST_HEAD(, ksem_mapping) *ksem_dictionary; 99 static struct sx ksem_dict_lock; 100 static struct mtx ksem_count_lock; 101 static struct mtx sem_lock; 102 static u_long ksem_hash; 103 static int ksem_dead; 104 105 #define KSEM_HASH(fnv) (&ksem_dictionary[(fnv) & ksem_hash]) 106 107 static int nsems = 0; 108 SYSCTL_DECL(_p1003_1b); 109 SYSCTL_INT(_p1003_1b, OID_AUTO, nsems, CTLFLAG_RD, &nsems, 0, 110 "Number of active kernel POSIX semaphores"); 111 112 static int kern_sem_wait(struct thread *td, semid_t id, int tryflag, 113 struct timespec *abstime); 114 static int ksem_access(struct ksem *ks, struct ucred *ucred); 115 static struct ksem *ksem_alloc(struct ucred *ucred, mode_t mode, 116 unsigned int value); 117 static int ksem_create(struct thread *td, const char *path, 118 semid_t *semidp, mode_t mode, unsigned int value, 119 int flags, int compat32); 120 static void ksem_drop(struct ksem *ks); 121 static int ksem_get(struct thread *td, semid_t id, cap_rights_t *rightsp, 122 struct file **fpp); 123 static struct ksem *ksem_hold(struct ksem *ks); 124 static void ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks); 125 static struct ksem *ksem_lookup(char *path, Fnv32_t fnv); 126 static void ksem_module_destroy(void); 127 static int ksem_module_init(void); 128 static int ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred); 129 static int sem_modload(struct module *module, int cmd, void *arg); 130 131 static fo_stat_t ksem_stat; 132 static fo_close_t ksem_closef; 133 static fo_chmod_t ksem_chmod; 134 static fo_chown_t ksem_chown; 135 static fo_fill_kinfo_t ksem_fill_kinfo; 136 137 /* File descriptor operations. */ 138 static struct fileops ksem_ops = { 139 .fo_read = invfo_rdwr, 140 .fo_write = invfo_rdwr, 141 .fo_truncate = invfo_truncate, 142 .fo_ioctl = invfo_ioctl, 143 .fo_poll = invfo_poll, 144 .fo_kqfilter = invfo_kqfilter, 145 .fo_stat = ksem_stat, 146 .fo_close = ksem_closef, 147 .fo_chmod = ksem_chmod, 148 .fo_chown = ksem_chown, 149 .fo_sendfile = invfo_sendfile, 150 .fo_fill_kinfo = ksem_fill_kinfo, 151 .fo_flags = DFLAG_PASSABLE 152 }; 153 154 FEATURE(posix_sem, "POSIX semaphores"); 155 156 static int 157 ksem_stat(struct file *fp, struct stat *sb, struct ucred *active_cred, 158 struct thread *td) 159 { 160 struct ksem *ks; 161 #ifdef MAC 162 int error; 163 #endif 164 165 ks = fp->f_data; 166 167 #ifdef MAC 168 error = mac_posixsem_check_stat(active_cred, fp->f_cred, ks); 169 if (error) 170 return (error); 171 #endif 172 173 /* 174 * Attempt to return sanish values for fstat() on a semaphore 175 * file descriptor. 176 */ 177 bzero(sb, sizeof(*sb)); 178 179 mtx_lock(&sem_lock); 180 sb->st_atim = ks->ks_atime; 181 sb->st_ctim = ks->ks_ctime; 182 sb->st_mtim = ks->ks_mtime; 183 sb->st_birthtim = ks->ks_birthtime; 184 sb->st_uid = ks->ks_uid; 185 sb->st_gid = ks->ks_gid; 186 sb->st_mode = S_IFREG | ks->ks_mode; /* XXX */ 187 mtx_unlock(&sem_lock); 188 189 return (0); 190 } 191 192 static int 193 ksem_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 194 struct thread *td) 195 { 196 struct ksem *ks; 197 int error; 198 199 error = 0; 200 ks = fp->f_data; 201 mtx_lock(&sem_lock); 202 #ifdef MAC 203 error = mac_posixsem_check_setmode(active_cred, ks, mode); 204 if (error != 0) 205 goto out; 206 #endif 207 error = vaccess(VREG, ks->ks_mode, ks->ks_uid, ks->ks_gid, VADMIN, 208 active_cred, NULL); 209 if (error != 0) 210 goto out; 211 ks->ks_mode = mode & ACCESSPERMS; 212 out: 213 mtx_unlock(&sem_lock); 214 return (error); 215 } 216 217 static int 218 ksem_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 219 struct thread *td) 220 { 221 struct ksem *ks; 222 int error; 223 224 error = 0; 225 ks = fp->f_data; 226 mtx_lock(&sem_lock); 227 #ifdef MAC 228 error = mac_posixsem_check_setowner(active_cred, ks, uid, gid); 229 if (error != 0) 230 goto out; 231 #endif 232 if (uid == (uid_t)-1) 233 uid = ks->ks_uid; 234 if (gid == (gid_t)-1) 235 gid = ks->ks_gid; 236 if (((uid != ks->ks_uid && uid != active_cred->cr_uid) || 237 (gid != ks->ks_gid && !groupmember(gid, active_cred))) && 238 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN, 0))) 239 goto out; 240 ks->ks_uid = uid; 241 ks->ks_gid = gid; 242 out: 243 mtx_unlock(&sem_lock); 244 return (error); 245 } 246 247 static int 248 ksem_closef(struct file *fp, struct thread *td) 249 { 250 struct ksem *ks; 251 252 ks = fp->f_data; 253 fp->f_data = NULL; 254 ksem_drop(ks); 255 256 return (0); 257 } 258 259 static int 260 ksem_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp) 261 { 262 const char *path, *pr_path; 263 struct ksem *ks; 264 size_t pr_pathlen; 265 266 kif->kf_type = KF_TYPE_SEM; 267 ks = fp->f_data; 268 mtx_lock(&sem_lock); 269 kif->kf_un.kf_sem.kf_sem_value = ks->ks_value; 270 kif->kf_un.kf_sem.kf_sem_mode = S_IFREG | ks->ks_mode; /* XXX */ 271 mtx_unlock(&sem_lock); 272 if (ks->ks_path != NULL) { 273 sx_slock(&ksem_dict_lock); 274 if (ks->ks_path != NULL) { 275 path = ks->ks_path; 276 pr_path = curthread->td_ucred->cr_prison->pr_path; 277 if (strcmp(pr_path, "/") != 0) { 278 /* Return the jail-rooted pathname. */ 279 pr_pathlen = strlen(pr_path); 280 if (strncmp(path, pr_path, pr_pathlen) == 0 && 281 path[pr_pathlen] == '/') 282 path += pr_pathlen; 283 } 284 strlcpy(kif->kf_path, path, sizeof(kif->kf_path)); 285 } 286 sx_sunlock(&ksem_dict_lock); 287 } 288 return (0); 289 } 290 291 /* 292 * ksem object management including creation and reference counting 293 * routines. 294 */ 295 static struct ksem * 296 ksem_alloc(struct ucred *ucred, mode_t mode, unsigned int value) 297 { 298 struct ksem *ks; 299 300 mtx_lock(&ksem_count_lock); 301 if (nsems == p31b_getcfg(CTL_P1003_1B_SEM_NSEMS_MAX) || ksem_dead) { 302 mtx_unlock(&ksem_count_lock); 303 return (NULL); 304 } 305 nsems++; 306 mtx_unlock(&ksem_count_lock); 307 ks = malloc(sizeof(*ks), M_KSEM, M_WAITOK | M_ZERO); 308 ks->ks_uid = ucred->cr_uid; 309 ks->ks_gid = ucred->cr_gid; 310 ks->ks_mode = mode; 311 ks->ks_value = value; 312 cv_init(&ks->ks_cv, "ksem"); 313 vfs_timestamp(&ks->ks_birthtime); 314 ks->ks_atime = ks->ks_mtime = ks->ks_ctime = ks->ks_birthtime; 315 refcount_init(&ks->ks_ref, 1); 316 #ifdef MAC 317 mac_posixsem_init(ks); 318 mac_posixsem_create(ucred, ks); 319 #endif 320 321 return (ks); 322 } 323 324 static struct ksem * 325 ksem_hold(struct ksem *ks) 326 { 327 328 refcount_acquire(&ks->ks_ref); 329 return (ks); 330 } 331 332 static void 333 ksem_drop(struct ksem *ks) 334 { 335 336 if (refcount_release(&ks->ks_ref)) { 337 #ifdef MAC 338 mac_posixsem_destroy(ks); 339 #endif 340 cv_destroy(&ks->ks_cv); 341 free(ks, M_KSEM); 342 mtx_lock(&ksem_count_lock); 343 nsems--; 344 mtx_unlock(&ksem_count_lock); 345 } 346 } 347 348 /* 349 * Determine if the credentials have sufficient permissions for read 350 * and write access. 351 */ 352 static int 353 ksem_access(struct ksem *ks, struct ucred *ucred) 354 { 355 int error; 356 357 error = vaccess(VREG, ks->ks_mode, ks->ks_uid, ks->ks_gid, 358 VREAD | VWRITE, ucred, NULL); 359 if (error) 360 error = priv_check_cred(ucred, PRIV_SEM_WRITE, 0); 361 return (error); 362 } 363 364 /* 365 * Dictionary management. We maintain an in-kernel dictionary to map 366 * paths to semaphore objects. We use the FNV hash on the path to 367 * store the mappings in a hash table. 368 */ 369 static struct ksem * 370 ksem_lookup(char *path, Fnv32_t fnv) 371 { 372 struct ksem_mapping *map; 373 374 LIST_FOREACH(map, KSEM_HASH(fnv), km_link) { 375 if (map->km_fnv != fnv) 376 continue; 377 if (strcmp(map->km_path, path) == 0) 378 return (map->km_ksem); 379 } 380 381 return (NULL); 382 } 383 384 static void 385 ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks) 386 { 387 struct ksem_mapping *map; 388 389 map = malloc(sizeof(struct ksem_mapping), M_KSEM, M_WAITOK); 390 map->km_path = path; 391 map->km_fnv = fnv; 392 map->km_ksem = ksem_hold(ks); 393 ks->ks_path = path; 394 LIST_INSERT_HEAD(KSEM_HASH(fnv), map, km_link); 395 } 396 397 static int 398 ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 399 { 400 struct ksem_mapping *map; 401 int error; 402 403 LIST_FOREACH(map, KSEM_HASH(fnv), km_link) { 404 if (map->km_fnv != fnv) 405 continue; 406 if (strcmp(map->km_path, path) == 0) { 407 #ifdef MAC 408 error = mac_posixsem_check_unlink(ucred, map->km_ksem); 409 if (error) 410 return (error); 411 #endif 412 error = ksem_access(map->km_ksem, ucred); 413 if (error) 414 return (error); 415 map->km_ksem->ks_path = NULL; 416 LIST_REMOVE(map, km_link); 417 ksem_drop(map->km_ksem); 418 free(map->km_path, M_KSEM); 419 free(map, M_KSEM); 420 return (0); 421 } 422 } 423 424 return (ENOENT); 425 } 426 427 static int 428 ksem_create_copyout_semid(struct thread *td, semid_t *semidp, int fd, 429 int compat32) 430 { 431 semid_t semid; 432 #ifdef COMPAT_FREEBSD32 433 int32_t semid32; 434 #endif 435 void *ptr; 436 size_t ptrs; 437 438 #ifdef COMPAT_FREEBSD32 439 if (compat32) { 440 semid32 = fd; 441 ptr = &semid32; 442 ptrs = sizeof(semid32); 443 } else { 444 #endif 445 semid = fd; 446 ptr = &semid; 447 ptrs = sizeof(semid); 448 compat32 = 0; /* silence gcc */ 449 #ifdef COMPAT_FREEBSD32 450 } 451 #endif 452 453 return (copyout(ptr, semidp, ptrs)); 454 } 455 456 /* Other helper routines. */ 457 static int 458 ksem_create(struct thread *td, const char *name, semid_t *semidp, mode_t mode, 459 unsigned int value, int flags, int compat32) 460 { 461 struct filedesc *fdp; 462 struct ksem *ks; 463 struct file *fp; 464 char *path; 465 const char *pr_path; 466 size_t pr_pathlen; 467 Fnv32_t fnv; 468 int error, fd; 469 470 if (value > SEM_VALUE_MAX) 471 return (EINVAL); 472 473 fdp = td->td_proc->p_fd; 474 mode = (mode & ~fdp->fd_cmask) & ACCESSPERMS; 475 error = falloc(td, &fp, &fd, O_CLOEXEC); 476 if (error) { 477 if (name == NULL) 478 error = ENOSPC; 479 return (error); 480 } 481 482 /* 483 * Go ahead and copyout the file descriptor now. This is a bit 484 * premature, but it is a lot easier to handle errors as opposed 485 * to later when we've possibly created a new semaphore, etc. 486 */ 487 error = ksem_create_copyout_semid(td, semidp, fd, compat32); 488 if (error) { 489 fdclose(td, fp, fd); 490 fdrop(fp, td); 491 return (error); 492 } 493 494 if (name == NULL) { 495 /* Create an anonymous semaphore. */ 496 ks = ksem_alloc(td->td_ucred, mode, value); 497 if (ks == NULL) 498 error = ENOSPC; 499 else 500 ks->ks_flags |= KS_ANONYMOUS; 501 } else { 502 path = malloc(MAXPATHLEN, M_KSEM, M_WAITOK); 503 pr_path = td->td_ucred->cr_prison->pr_path; 504 505 /* Construct a full pathname for jailed callers. */ 506 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0 507 : strlcpy(path, pr_path, MAXPATHLEN); 508 error = copyinstr(name, path + pr_pathlen, 509 MAXPATHLEN - pr_pathlen, NULL); 510 511 /* Require paths to start with a '/' character. */ 512 if (error == 0 && path[pr_pathlen] != '/') 513 error = EINVAL; 514 if (error) { 515 fdclose(td, fp, fd); 516 fdrop(fp, td); 517 free(path, M_KSEM); 518 return (error); 519 } 520 521 fnv = fnv_32_str(path, FNV1_32_INIT); 522 sx_xlock(&ksem_dict_lock); 523 ks = ksem_lookup(path, fnv); 524 if (ks == NULL) { 525 /* Object does not exist, create it if requested. */ 526 if (flags & O_CREAT) { 527 ks = ksem_alloc(td->td_ucred, mode, value); 528 if (ks == NULL) 529 error = ENFILE; 530 else { 531 ksem_insert(path, fnv, ks); 532 path = NULL; 533 } 534 } else 535 error = ENOENT; 536 } else { 537 /* 538 * Object already exists, obtain a new 539 * reference if requested and permitted. 540 */ 541 if ((flags & (O_CREAT | O_EXCL)) == 542 (O_CREAT | O_EXCL)) 543 error = EEXIST; 544 else { 545 #ifdef MAC 546 error = mac_posixsem_check_open(td->td_ucred, 547 ks); 548 if (error == 0) 549 #endif 550 error = ksem_access(ks, td->td_ucred); 551 } 552 if (error == 0) 553 ksem_hold(ks); 554 #ifdef INVARIANTS 555 else 556 ks = NULL; 557 #endif 558 } 559 sx_xunlock(&ksem_dict_lock); 560 if (path) 561 free(path, M_KSEM); 562 } 563 564 if (error) { 565 KASSERT(ks == NULL, ("ksem_create error with a ksem")); 566 fdclose(td, fp, fd); 567 fdrop(fp, td); 568 return (error); 569 } 570 KASSERT(ks != NULL, ("ksem_create w/o a ksem")); 571 572 finit(fp, FREAD | FWRITE, DTYPE_SEM, ks, &ksem_ops); 573 574 fdrop(fp, td); 575 576 return (0); 577 } 578 579 static int 580 ksem_get(struct thread *td, semid_t id, cap_rights_t *rightsp, 581 struct file **fpp) 582 { 583 struct ksem *ks; 584 struct file *fp; 585 int error; 586 587 error = fget(td, id, rightsp, &fp); 588 if (error) 589 return (EINVAL); 590 if (fp->f_type != DTYPE_SEM) { 591 fdrop(fp, td); 592 return (EINVAL); 593 } 594 ks = fp->f_data; 595 if (ks->ks_flags & KS_DEAD) { 596 fdrop(fp, td); 597 return (EINVAL); 598 } 599 *fpp = fp; 600 return (0); 601 } 602 603 /* System calls. */ 604 #ifndef _SYS_SYSPROTO_H_ 605 struct ksem_init_args { 606 unsigned int value; 607 semid_t *idp; 608 }; 609 #endif 610 int 611 sys_ksem_init(struct thread *td, struct ksem_init_args *uap) 612 { 613 614 return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value, 615 0, 0)); 616 } 617 618 #ifndef _SYS_SYSPROTO_H_ 619 struct ksem_open_args { 620 char *name; 621 int oflag; 622 mode_t mode; 623 unsigned int value; 624 semid_t *idp; 625 }; 626 #endif 627 int 628 sys_ksem_open(struct thread *td, struct ksem_open_args *uap) 629 { 630 631 DP((">>> ksem_open start, pid=%d\n", (int)td->td_proc->p_pid)); 632 633 if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0) 634 return (EINVAL); 635 return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value, 636 uap->oflag, 0)); 637 } 638 639 #ifndef _SYS_SYSPROTO_H_ 640 struct ksem_unlink_args { 641 char *name; 642 }; 643 #endif 644 int 645 sys_ksem_unlink(struct thread *td, struct ksem_unlink_args *uap) 646 { 647 char *path; 648 const char *pr_path; 649 size_t pr_pathlen; 650 Fnv32_t fnv; 651 int error; 652 653 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 654 pr_path = td->td_ucred->cr_prison->pr_path; 655 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0 656 : strlcpy(path, pr_path, MAXPATHLEN); 657 error = copyinstr(uap->name, path + pr_pathlen, MAXPATHLEN - pr_pathlen, 658 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 cap_rights_t rights; 682 struct ksem *ks; 683 struct file *fp; 684 int error; 685 686 /* No capability rights required to close a semaphore. */ 687 error = ksem_get(td, uap->id, cap_rights_init(&rights), &fp); 688 if (error) 689 return (error); 690 ks = fp->f_data; 691 if (ks->ks_flags & KS_ANONYMOUS) { 692 fdrop(fp, td); 693 return (EINVAL); 694 } 695 error = kern_close(td, uap->id); 696 fdrop(fp, td); 697 return (error); 698 } 699 700 #ifndef _SYS_SYSPROTO_H_ 701 struct ksem_post_args { 702 semid_t id; 703 }; 704 #endif 705 int 706 sys_ksem_post(struct thread *td, struct ksem_post_args *uap) 707 { 708 cap_rights_t rights; 709 struct file *fp; 710 struct ksem *ks; 711 int error; 712 713 error = ksem_get(td, uap->id, 714 cap_rights_init(&rights, CAP_SEM_POST), &fp); 715 if (error) 716 return (error); 717 ks = fp->f_data; 718 719 mtx_lock(&sem_lock); 720 #ifdef MAC 721 error = mac_posixsem_check_post(td->td_ucred, fp->f_cred, ks); 722 if (error) 723 goto err; 724 #endif 725 if (ks->ks_value == SEM_VALUE_MAX) { 726 error = EOVERFLOW; 727 goto err; 728 } 729 ++ks->ks_value; 730 if (ks->ks_waiters > 0) 731 cv_signal(&ks->ks_cv); 732 error = 0; 733 vfs_timestamp(&ks->ks_ctime); 734 err: 735 mtx_unlock(&sem_lock); 736 fdrop(fp, td); 737 return (error); 738 } 739 740 #ifndef _SYS_SYSPROTO_H_ 741 struct ksem_wait_args { 742 semid_t id; 743 }; 744 #endif 745 int 746 sys_ksem_wait(struct thread *td, struct ksem_wait_args *uap) 747 { 748 749 return (kern_sem_wait(td, uap->id, 0, NULL)); 750 } 751 752 #ifndef _SYS_SYSPROTO_H_ 753 struct ksem_timedwait_args { 754 semid_t id; 755 const struct timespec *abstime; 756 }; 757 #endif 758 int 759 sys_ksem_timedwait(struct thread *td, struct ksem_timedwait_args *uap) 760 { 761 struct timespec abstime; 762 struct timespec *ts; 763 int error; 764 765 /* 766 * We allow a null timespec (wait forever). 767 */ 768 if (uap->abstime == NULL) 769 ts = NULL; 770 else { 771 error = copyin(uap->abstime, &abstime, sizeof(abstime)); 772 if (error != 0) 773 return (error); 774 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0) 775 return (EINVAL); 776 ts = &abstime; 777 } 778 return (kern_sem_wait(td, uap->id, 0, ts)); 779 } 780 781 #ifndef _SYS_SYSPROTO_H_ 782 struct ksem_trywait_args { 783 semid_t id; 784 }; 785 #endif 786 int 787 sys_ksem_trywait(struct thread *td, struct ksem_trywait_args *uap) 788 { 789 790 return (kern_sem_wait(td, uap->id, 1, NULL)); 791 } 792 793 static int 794 kern_sem_wait(struct thread *td, semid_t id, int tryflag, 795 struct timespec *abstime) 796 { 797 struct timespec ts1, ts2; 798 struct timeval tv; 799 cap_rights_t rights; 800 struct file *fp; 801 struct ksem *ks; 802 int error; 803 804 DP((">>> kern_sem_wait entered! pid=%d\n", (int)td->td_proc->p_pid)); 805 error = ksem_get(td, id, cap_rights_init(&rights, CAP_SEM_WAIT), &fp); 806 if (error) 807 return (error); 808 ks = fp->f_data; 809 mtx_lock(&sem_lock); 810 DP((">>> kern_sem_wait critical section entered! pid=%d\n", 811 (int)td->td_proc->p_pid)); 812 #ifdef MAC 813 error = mac_posixsem_check_wait(td->td_ucred, fp->f_cred, ks); 814 if (error) { 815 DP(("kern_sem_wait mac failed\n")); 816 goto err; 817 } 818 #endif 819 DP(("kern_sem_wait value = %d, tryflag %d\n", ks->ks_value, tryflag)); 820 vfs_timestamp(&ks->ks_atime); 821 while (ks->ks_value == 0) { 822 ks->ks_waiters++; 823 if (tryflag != 0) 824 error = EAGAIN; 825 else if (abstime == NULL) 826 error = cv_wait_sig(&ks->ks_cv, &sem_lock); 827 else { 828 for (;;) { 829 ts1 = *abstime; 830 getnanotime(&ts2); 831 timespecsub(&ts1, &ts2); 832 TIMESPEC_TO_TIMEVAL(&tv, &ts1); 833 if (tv.tv_sec < 0) { 834 error = ETIMEDOUT; 835 break; 836 } 837 error = cv_timedwait_sig(&ks->ks_cv, 838 &sem_lock, tvtohz(&tv)); 839 if (error != EWOULDBLOCK) 840 break; 841 } 842 } 843 ks->ks_waiters--; 844 if (error) 845 goto err; 846 } 847 ks->ks_value--; 848 DP(("kern_sem_wait value post-decrement = %d\n", ks->ks_value)); 849 error = 0; 850 err: 851 mtx_unlock(&sem_lock); 852 fdrop(fp, td); 853 DP(("<<< kern_sem_wait leaving, pid=%d, error = %d\n", 854 (int)td->td_proc->p_pid, error)); 855 return (error); 856 } 857 858 #ifndef _SYS_SYSPROTO_H_ 859 struct ksem_getvalue_args { 860 semid_t id; 861 int *val; 862 }; 863 #endif 864 int 865 sys_ksem_getvalue(struct thread *td, struct ksem_getvalue_args *uap) 866 { 867 cap_rights_t rights; 868 struct file *fp; 869 struct ksem *ks; 870 int error, val; 871 872 error = ksem_get(td, uap->id, 873 cap_rights_init(&rights, CAP_SEM_GETVALUE), &fp); 874 if (error) 875 return (error); 876 ks = fp->f_data; 877 878 mtx_lock(&sem_lock); 879 #ifdef MAC 880 error = mac_posixsem_check_getvalue(td->td_ucred, fp->f_cred, ks); 881 if (error) { 882 mtx_unlock(&sem_lock); 883 fdrop(fp, td); 884 return (error); 885 } 886 #endif 887 val = ks->ks_value; 888 vfs_timestamp(&ks->ks_atime); 889 mtx_unlock(&sem_lock); 890 fdrop(fp, td); 891 error = copyout(&val, uap->val, sizeof(val)); 892 return (error); 893 } 894 895 #ifndef _SYS_SYSPROTO_H_ 896 struct ksem_destroy_args { 897 semid_t id; 898 }; 899 #endif 900 int 901 sys_ksem_destroy(struct thread *td, struct ksem_destroy_args *uap) 902 { 903 cap_rights_t rights; 904 struct file *fp; 905 struct ksem *ks; 906 int error; 907 908 /* No capability rights required to close a semaphore. */ 909 error = ksem_get(td, uap->id, cap_rights_init(&rights), &fp); 910 if (error) 911 return (error); 912 ks = fp->f_data; 913 if (!(ks->ks_flags & KS_ANONYMOUS)) { 914 fdrop(fp, td); 915 return (EINVAL); 916 } 917 mtx_lock(&sem_lock); 918 if (ks->ks_waiters != 0) { 919 mtx_unlock(&sem_lock); 920 error = EBUSY; 921 goto err; 922 } 923 ks->ks_flags |= KS_DEAD; 924 mtx_unlock(&sem_lock); 925 926 error = kern_close(td, uap->id); 927 err: 928 fdrop(fp, td); 929 return (error); 930 } 931 932 static struct syscall_helper_data ksem_syscalls[] = { 933 SYSCALL_INIT_HELPER(ksem_init), 934 SYSCALL_INIT_HELPER(ksem_open), 935 SYSCALL_INIT_HELPER(ksem_unlink), 936 SYSCALL_INIT_HELPER(ksem_close), 937 SYSCALL_INIT_HELPER(ksem_post), 938 SYSCALL_INIT_HELPER(ksem_wait), 939 SYSCALL_INIT_HELPER(ksem_timedwait), 940 SYSCALL_INIT_HELPER(ksem_trywait), 941 SYSCALL_INIT_HELPER(ksem_getvalue), 942 SYSCALL_INIT_HELPER(ksem_destroy), 943 SYSCALL_INIT_LAST 944 }; 945 946 #ifdef COMPAT_FREEBSD32 947 #include <compat/freebsd32/freebsd32.h> 948 #include <compat/freebsd32/freebsd32_proto.h> 949 #include <compat/freebsd32/freebsd32_signal.h> 950 #include <compat/freebsd32/freebsd32_syscall.h> 951 #include <compat/freebsd32/freebsd32_util.h> 952 953 int 954 freebsd32_ksem_init(struct thread *td, struct freebsd32_ksem_init_args *uap) 955 { 956 957 return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value, 958 0, 1)); 959 } 960 961 int 962 freebsd32_ksem_open(struct thread *td, struct freebsd32_ksem_open_args *uap) 963 { 964 965 if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0) 966 return (EINVAL); 967 return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value, 968 uap->oflag, 1)); 969 } 970 971 int 972 freebsd32_ksem_timedwait(struct thread *td, 973 struct freebsd32_ksem_timedwait_args *uap) 974 { 975 struct timespec32 abstime32; 976 struct timespec *ts, abstime; 977 int error; 978 979 /* 980 * We allow a null timespec (wait forever). 981 */ 982 if (uap->abstime == NULL) 983 ts = NULL; 984 else { 985 error = copyin(uap->abstime, &abstime32, sizeof(abstime32)); 986 if (error != 0) 987 return (error); 988 CP(abstime32, abstime, tv_sec); 989 CP(abstime32, abstime, tv_nsec); 990 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0) 991 return (EINVAL); 992 ts = &abstime; 993 } 994 return (kern_sem_wait(td, uap->id, 0, ts)); 995 } 996 997 static struct syscall_helper_data ksem32_syscalls[] = { 998 SYSCALL32_INIT_HELPER(freebsd32_ksem_init), 999 SYSCALL32_INIT_HELPER(freebsd32_ksem_open), 1000 SYSCALL32_INIT_HELPER_COMPAT(ksem_unlink), 1001 SYSCALL32_INIT_HELPER_COMPAT(ksem_close), 1002 SYSCALL32_INIT_HELPER_COMPAT(ksem_post), 1003 SYSCALL32_INIT_HELPER_COMPAT(ksem_wait), 1004 SYSCALL32_INIT_HELPER(freebsd32_ksem_timedwait), 1005 SYSCALL32_INIT_HELPER_COMPAT(ksem_trywait), 1006 SYSCALL32_INIT_HELPER_COMPAT(ksem_getvalue), 1007 SYSCALL32_INIT_HELPER_COMPAT(ksem_destroy), 1008 SYSCALL_INIT_LAST 1009 }; 1010 #endif 1011 1012 static int 1013 ksem_module_init(void) 1014 { 1015 int error; 1016 1017 mtx_init(&sem_lock, "sem", NULL, MTX_DEF); 1018 mtx_init(&ksem_count_lock, "ksem count", NULL, MTX_DEF); 1019 sx_init(&ksem_dict_lock, "ksem dictionary"); 1020 ksem_dictionary = hashinit(1024, M_KSEM, &ksem_hash); 1021 p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 200112L); 1022 p31b_setcfg(CTL_P1003_1B_SEM_NSEMS_MAX, SEM_MAX); 1023 p31b_setcfg(CTL_P1003_1B_SEM_VALUE_MAX, SEM_VALUE_MAX); 1024 1025 error = syscall_helper_register(ksem_syscalls, SY_THR_STATIC_KLD); 1026 if (error) 1027 return (error); 1028 #ifdef COMPAT_FREEBSD32 1029 error = syscall32_helper_register(ksem32_syscalls, SY_THR_STATIC_KLD); 1030 if (error) 1031 return (error); 1032 #endif 1033 return (0); 1034 } 1035 1036 static void 1037 ksem_module_destroy(void) 1038 { 1039 1040 #ifdef COMPAT_FREEBSD32 1041 syscall32_helper_unregister(ksem32_syscalls); 1042 #endif 1043 syscall_helper_unregister(ksem_syscalls); 1044 1045 p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 0); 1046 hashdestroy(ksem_dictionary, M_KSEM, ksem_hash); 1047 sx_destroy(&ksem_dict_lock); 1048 mtx_destroy(&ksem_count_lock); 1049 mtx_destroy(&sem_lock); 1050 p31b_unsetcfg(CTL_P1003_1B_SEM_VALUE_MAX); 1051 p31b_unsetcfg(CTL_P1003_1B_SEM_NSEMS_MAX); 1052 } 1053 1054 static int 1055 sem_modload(struct module *module, int cmd, void *arg) 1056 { 1057 int error = 0; 1058 1059 switch (cmd) { 1060 case MOD_LOAD: 1061 error = ksem_module_init(); 1062 if (error) 1063 ksem_module_destroy(); 1064 break; 1065 1066 case MOD_UNLOAD: 1067 mtx_lock(&ksem_count_lock); 1068 if (nsems != 0) { 1069 error = EOPNOTSUPP; 1070 mtx_unlock(&ksem_count_lock); 1071 break; 1072 } 1073 ksem_dead = 1; 1074 mtx_unlock(&ksem_count_lock); 1075 ksem_module_destroy(); 1076 break; 1077 1078 case MOD_SHUTDOWN: 1079 break; 1080 default: 1081 error = EINVAL; 1082 break; 1083 } 1084 return (error); 1085 } 1086 1087 static moduledata_t sem_mod = { 1088 "sem", 1089 &sem_modload, 1090 NULL 1091 }; 1092 1093 DECLARE_MODULE(sem, sem_mod, SI_SUB_SYSV_SEM, SI_ORDER_FIRST); 1094 MODULE_VERSION(sem, 1);
Cache object: 4a9288c623a4472fe4a098b1d6770efd
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