FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_sem.c
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/8.3/sys/kern/uipc_sem.c 217845 2011-01-25 20:54:15Z jhb $");
36
37 #include "opt_compat.h"
38 #include "opt_posix.h"
39
40 #include <sys/param.h>
41 #include <sys/condvar.h>
42 #include <sys/fcntl.h>
43 #include <sys/file.h>
44 #include <sys/filedesc.h>
45 #include <sys/fnv_hash.h>
46 #include <sys/kernel.h>
47 #include <sys/ksem.h>
48 #include <sys/lock.h>
49 #include <sys/malloc.h>
50 #include <sys/module.h>
51 #include <sys/mutex.h>
52 #include <sys/priv.h>
53 #include <sys/proc.h>
54 #include <sys/posix4.h>
55 #include <sys/semaphore.h>
56 #include <sys/_semaphore.h>
57 #include <sys/stat.h>
58 #include <sys/syscall.h>
59 #include <sys/syscallsubr.h>
60 #include <sys/sysctl.h>
61 #include <sys/sysent.h>
62 #include <sys/sysproto.h>
63 #include <sys/systm.h>
64 #include <sys/sx.h>
65 #include <sys/vnode.h>
66
67 #include <security/mac/mac_framework.h>
68
69 /*
70 * TODO
71 *
72 * - Resource limits?
73 * - Update fstat(1)
74 * - Replace global sem_lock with mtx_pool locks?
75 * - Add a MAC check_create() hook for creating new named semaphores.
76 */
77
78 #ifndef SEM_MAX
79 #define SEM_MAX 30
80 #endif
81
82 #ifdef SEM_DEBUG
83 #define DP(x) printf x
84 #else
85 #define DP(x)
86 #endif
87
88 struct ksem_mapping {
89 char *km_path;
90 Fnv32_t km_fnv;
91 struct ksem *km_ksem;
92 LIST_ENTRY(ksem_mapping) km_link;
93 };
94
95 static MALLOC_DEFINE(M_KSEM, "ksem", "semaphore file descriptor");
96 static LIST_HEAD(, ksem_mapping) *ksem_dictionary;
97 static struct sx ksem_dict_lock;
98 static struct mtx ksem_count_lock;
99 static struct mtx sem_lock;
100 static u_long ksem_hash;
101 static int ksem_dead;
102
103 #define KSEM_HASH(fnv) (&ksem_dictionary[(fnv) & ksem_hash])
104
105 static int nsems = 0;
106 SYSCTL_DECL(_p1003_1b);
107 SYSCTL_INT(_p1003_1b, OID_AUTO, nsems, CTLFLAG_RD, &nsems, 0,
108 "Number of active kernel POSIX semaphores");
109
110 static int kern_sem_wait(struct thread *td, semid_t id, int tryflag,
111 struct timespec *abstime);
112 static int ksem_access(struct ksem *ks, struct ucred *ucred);
113 static struct ksem *ksem_alloc(struct ucred *ucred, mode_t mode,
114 unsigned int value);
115 static int ksem_create(struct thread *td, const char *path,
116 semid_t *semidp, mode_t mode, unsigned int value,
117 int flags, int compat32);
118 static void ksem_drop(struct ksem *ks);
119 static int ksem_get(struct thread *td, semid_t id, struct file **fpp);
120 static struct ksem *ksem_hold(struct ksem *ks);
121 static void ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks);
122 static struct ksem *ksem_lookup(char *path, Fnv32_t fnv);
123 static void ksem_module_destroy(void);
124 static int ksem_module_init(void);
125 static int ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred);
126 static int sem_modload(struct module *module, int cmd, void *arg);
127
128 static fo_rdwr_t ksem_read;
129 static fo_rdwr_t ksem_write;
130 static fo_truncate_t ksem_truncate;
131 static fo_ioctl_t ksem_ioctl;
132 static fo_poll_t ksem_poll;
133 static fo_kqfilter_t ksem_kqfilter;
134 static fo_stat_t ksem_stat;
135 static fo_close_t ksem_closef;
136
137 /* File descriptor operations. */
138 static struct fileops ksem_ops = {
139 .fo_read = ksem_read,
140 .fo_write = ksem_write,
141 .fo_truncate = ksem_truncate,
142 .fo_ioctl = ksem_ioctl,
143 .fo_poll = ksem_poll,
144 .fo_kqfilter = ksem_kqfilter,
145 .fo_stat = ksem_stat,
146 .fo_close = ksem_closef,
147 .fo_flags = DFLAG_PASSABLE
148 };
149
150 FEATURE(posix_sem, "POSIX semaphores");
151
152 static int
153 ksem_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
154 int flags, struct thread *td)
155 {
156
157 return (EOPNOTSUPP);
158 }
159
160 static int
161 ksem_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
162 int flags, struct thread *td)
163 {
164
165 return (EOPNOTSUPP);
166 }
167
168 static int
169 ksem_truncate(struct file *fp, off_t length, struct ucred *active_cred,
170 struct thread *td)
171 {
172
173 return (EINVAL);
174 }
175
176 static int
177 ksem_ioctl(struct file *fp, u_long com, void *data,
178 struct ucred *active_cred, struct thread *td)
179 {
180
181 return (EOPNOTSUPP);
182 }
183
184 static int
185 ksem_poll(struct file *fp, int events, struct ucred *active_cred,
186 struct thread *td)
187 {
188
189 return (EOPNOTSUPP);
190 }
191
192 static int
193 ksem_kqfilter(struct file *fp, struct knote *kn)
194 {
195
196 return (EOPNOTSUPP);
197 }
198
199 static int
200 ksem_stat(struct file *fp, struct stat *sb, struct ucred *active_cred,
201 struct thread *td)
202 {
203 struct ksem *ks;
204 #ifdef MAC
205 int error;
206 #endif
207
208 ks = fp->f_data;
209
210 #ifdef MAC
211 error = mac_posixsem_check_stat(active_cred, fp->f_cred, ks);
212 if (error)
213 return (error);
214 #endif
215
216 /*
217 * Attempt to return sanish values for fstat() on a semaphore
218 * file descriptor.
219 */
220 bzero(sb, sizeof(*sb));
221 sb->st_mode = S_IFREG | ks->ks_mode; /* XXX */
222
223 sb->st_atimespec = ks->ks_atime;
224 sb->st_ctimespec = ks->ks_ctime;
225 sb->st_mtimespec = ks->ks_mtime;
226 sb->st_birthtimespec = ks->ks_birthtime;
227 sb->st_uid = ks->ks_uid;
228 sb->st_gid = ks->ks_gid;
229
230 return (0);
231 }
232
233 static int
234 ksem_closef(struct file *fp, struct thread *td)
235 {
236 struct ksem *ks;
237
238 ks = fp->f_data;
239 fp->f_data = NULL;
240 ksem_drop(ks);
241
242 return (0);
243 }
244
245 /*
246 * ksem object management including creation and reference counting
247 * routines.
248 */
249 static struct ksem *
250 ksem_alloc(struct ucred *ucred, mode_t mode, unsigned int value)
251 {
252 struct ksem *ks;
253
254 mtx_lock(&ksem_count_lock);
255 if (nsems == p31b_getcfg(CTL_P1003_1B_SEM_NSEMS_MAX) || ksem_dead) {
256 mtx_unlock(&ksem_count_lock);
257 return (NULL);
258 }
259 nsems++;
260 mtx_unlock(&ksem_count_lock);
261 ks = malloc(sizeof(*ks), M_KSEM, M_WAITOK | M_ZERO);
262 ks->ks_uid = ucred->cr_uid;
263 ks->ks_gid = ucred->cr_gid;
264 ks->ks_mode = mode;
265 ks->ks_value = value;
266 cv_init(&ks->ks_cv, "ksem");
267 vfs_timestamp(&ks->ks_birthtime);
268 ks->ks_atime = ks->ks_mtime = ks->ks_ctime = ks->ks_birthtime;
269 refcount_init(&ks->ks_ref, 1);
270 #ifdef MAC
271 mac_posixsem_init(ks);
272 mac_posixsem_create(ucred, ks);
273 #endif
274
275 return (ks);
276 }
277
278 static struct ksem *
279 ksem_hold(struct ksem *ks)
280 {
281
282 refcount_acquire(&ks->ks_ref);
283 return (ks);
284 }
285
286 static void
287 ksem_drop(struct ksem *ks)
288 {
289
290 if (refcount_release(&ks->ks_ref)) {
291 #ifdef MAC
292 mac_posixsem_destroy(ks);
293 #endif
294 cv_destroy(&ks->ks_cv);
295 free(ks, M_KSEM);
296 mtx_lock(&ksem_count_lock);
297 nsems--;
298 mtx_unlock(&ksem_count_lock);
299 }
300 }
301
302 /*
303 * Determine if the credentials have sufficient permissions for read
304 * and write access.
305 */
306 static int
307 ksem_access(struct ksem *ks, struct ucred *ucred)
308 {
309 int error;
310
311 error = vaccess(VREG, ks->ks_mode, ks->ks_uid, ks->ks_gid,
312 VREAD | VWRITE, ucred, NULL);
313 if (error)
314 error = priv_check_cred(ucred, PRIV_SEM_WRITE, 0);
315 return (error);
316 }
317
318 /*
319 * Dictionary management. We maintain an in-kernel dictionary to map
320 * paths to semaphore objects. We use the FNV hash on the path to
321 * store the mappings in a hash table.
322 */
323 static struct ksem *
324 ksem_lookup(char *path, Fnv32_t fnv)
325 {
326 struct ksem_mapping *map;
327
328 LIST_FOREACH(map, KSEM_HASH(fnv), km_link) {
329 if (map->km_fnv != fnv)
330 continue;
331 if (strcmp(map->km_path, path) == 0)
332 return (map->km_ksem);
333 }
334
335 return (NULL);
336 }
337
338 static void
339 ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks)
340 {
341 struct ksem_mapping *map;
342
343 map = malloc(sizeof(struct ksem_mapping), M_KSEM, M_WAITOK);
344 map->km_path = path;
345 map->km_fnv = fnv;
346 map->km_ksem = ksem_hold(ks);
347 LIST_INSERT_HEAD(KSEM_HASH(fnv), map, km_link);
348 }
349
350 static int
351 ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred)
352 {
353 struct ksem_mapping *map;
354 int error;
355
356 LIST_FOREACH(map, KSEM_HASH(fnv), km_link) {
357 if (map->km_fnv != fnv)
358 continue;
359 if (strcmp(map->km_path, path) == 0) {
360 #ifdef MAC
361 error = mac_posixsem_check_unlink(ucred, map->km_ksem);
362 if (error)
363 return (error);
364 #endif
365 error = ksem_access(map->km_ksem, ucred);
366 if (error)
367 return (error);
368 LIST_REMOVE(map, km_link);
369 ksem_drop(map->km_ksem);
370 free(map->km_path, M_KSEM);
371 free(map, M_KSEM);
372 return (0);
373 }
374 }
375
376 return (ENOENT);
377 }
378
379 static int
380 ksem_create_copyout_semid(struct thread *td, semid_t *semidp, int fd,
381 int compat32)
382 {
383 semid_t semid;
384 #ifdef COMPAT_FREEBSD32
385 int32_t semid32;
386 #endif
387 void *ptr;
388 size_t ptrs;
389
390 #ifdef COMPAT_FREEBSD32
391 if (compat32) {
392 semid32 = fd;
393 ptr = &semid32;
394 ptrs = sizeof(semid32);
395 } else {
396 #endif
397 semid = fd;
398 ptr = &semid;
399 ptrs = sizeof(semid);
400 compat32 = 0; /* silence gcc */
401 #ifdef COMPAT_FREEBSD32
402 }
403 #endif
404
405 return (copyout(ptr, semidp, ptrs));
406 }
407
408 /* Other helper routines. */
409 static int
410 ksem_create(struct thread *td, const char *name, semid_t *semidp, mode_t mode,
411 unsigned int value, int flags, int compat32)
412 {
413 struct filedesc *fdp;
414 struct ksem *ks;
415 struct file *fp;
416 char *path;
417 Fnv32_t fnv;
418 int error, fd;
419
420 if (value > SEM_VALUE_MAX)
421 return (EINVAL);
422
423 fdp = td->td_proc->p_fd;
424 mode = (mode & ~fdp->fd_cmask) & ACCESSPERMS;
425 error = falloc(td, &fp, &fd);
426 if (error) {
427 if (name == NULL)
428 error = ENOSPC;
429 return (error);
430 }
431
432 /*
433 * Go ahead and copyout the file descriptor now. This is a bit
434 * premature, but it is a lot easier to handle errors as opposed
435 * to later when we've possibly created a new semaphore, etc.
436 */
437 error = ksem_create_copyout_semid(td, semidp, fd, compat32);
438 if (error) {
439 fdclose(fdp, fp, fd, td);
440 fdrop(fp, td);
441 return (error);
442 }
443
444 if (name == NULL) {
445 /* Create an anonymous semaphore. */
446 ks = ksem_alloc(td->td_ucred, mode, value);
447 if (ks == NULL)
448 error = ENOSPC;
449 else
450 ks->ks_flags |= KS_ANONYMOUS;
451 } else {
452 path = malloc(MAXPATHLEN, M_KSEM, M_WAITOK);
453 error = copyinstr(name, path, MAXPATHLEN, NULL);
454
455 /* Require paths to start with a '/' character. */
456 if (error == 0 && path[0] != '/')
457 error = EINVAL;
458 if (error) {
459 fdclose(fdp, fp, fd, td);
460 fdrop(fp, td);
461 free(path, M_KSEM);
462 return (error);
463 }
464
465 fnv = fnv_32_str(path, FNV1_32_INIT);
466 sx_xlock(&ksem_dict_lock);
467 ks = ksem_lookup(path, fnv);
468 if (ks == NULL) {
469 /* Object does not exist, create it if requested. */
470 if (flags & O_CREAT) {
471 ks = ksem_alloc(td->td_ucred, mode, value);
472 if (ks == NULL)
473 error = ENFILE;
474 else {
475 ksem_insert(path, fnv, ks);
476 path = NULL;
477 }
478 } else
479 error = ENOENT;
480 } else {
481 /*
482 * Object already exists, obtain a new
483 * reference if requested and permitted.
484 */
485 if ((flags & (O_CREAT | O_EXCL)) ==
486 (O_CREAT | O_EXCL))
487 error = EEXIST;
488 else {
489 #ifdef MAC
490 error = mac_posixsem_check_open(td->td_ucred,
491 ks);
492 if (error == 0)
493 #endif
494 error = ksem_access(ks, td->td_ucred);
495 }
496 if (error == 0)
497 ksem_hold(ks);
498 #ifdef INVARIANTS
499 else
500 ks = NULL;
501 #endif
502 }
503 sx_xunlock(&ksem_dict_lock);
504 if (path)
505 free(path, M_KSEM);
506 }
507
508 if (error) {
509 KASSERT(ks == NULL, ("ksem_create error with a ksem"));
510 fdclose(fdp, fp, fd, td);
511 fdrop(fp, td);
512 return (error);
513 }
514 KASSERT(ks != NULL, ("ksem_create w/o a ksem"));
515
516 finit(fp, FREAD | FWRITE, DTYPE_SEM, ks, &ksem_ops);
517
518 FILEDESC_XLOCK(fdp);
519 if (fdp->fd_ofiles[fd] == fp)
520 fdp->fd_ofileflags[fd] |= UF_EXCLOSE;
521 FILEDESC_XUNLOCK(fdp);
522 fdrop(fp, td);
523
524 return (0);
525 }
526
527 static int
528 ksem_get(struct thread *td, semid_t id, struct file **fpp)
529 {
530 struct ksem *ks;
531 struct file *fp;
532 int error;
533
534 error = fget(td, id, &fp);
535 if (error)
536 return (EINVAL);
537 if (fp->f_type != DTYPE_SEM) {
538 fdrop(fp, td);
539 return (EINVAL);
540 }
541 ks = fp->f_data;
542 if (ks->ks_flags & KS_DEAD) {
543 fdrop(fp, td);
544 return (EINVAL);
545 }
546 *fpp = fp;
547 return (0);
548 }
549
550 /* System calls. */
551 #ifndef _SYS_SYSPROTO_H_
552 struct ksem_init_args {
553 unsigned int value;
554 semid_t *idp;
555 };
556 #endif
557 int
558 ksem_init(struct thread *td, struct ksem_init_args *uap)
559 {
560
561 return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value,
562 0, 0));
563 }
564
565 #ifndef _SYS_SYSPROTO_H_
566 struct ksem_open_args {
567 char *name;
568 int oflag;
569 mode_t mode;
570 unsigned int value;
571 semid_t *idp;
572 };
573 #endif
574 int
575 ksem_open(struct thread *td, struct ksem_open_args *uap)
576 {
577
578 DP((">>> ksem_open start, pid=%d\n", (int)td->td_proc->p_pid));
579
580 if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0)
581 return (EINVAL);
582 return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value,
583 uap->oflag, 0));
584 }
585
586 #ifndef _SYS_SYSPROTO_H_
587 struct ksem_unlink_args {
588 char *name;
589 };
590 #endif
591 int
592 ksem_unlink(struct thread *td, struct ksem_unlink_args *uap)
593 {
594 char *path;
595 Fnv32_t fnv;
596 int error;
597
598 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
599 error = copyinstr(uap->name, path, MAXPATHLEN, NULL);
600 if (error) {
601 free(path, M_TEMP);
602 return (error);
603 }
604
605 fnv = fnv_32_str(path, FNV1_32_INIT);
606 sx_xlock(&ksem_dict_lock);
607 error = ksem_remove(path, fnv, td->td_ucred);
608 sx_xunlock(&ksem_dict_lock);
609 free(path, M_TEMP);
610
611 return (error);
612 }
613
614 #ifndef _SYS_SYSPROTO_H_
615 struct ksem_close_args {
616 semid_t id;
617 };
618 #endif
619 int
620 ksem_close(struct thread *td, struct ksem_close_args *uap)
621 {
622 struct ksem *ks;
623 struct file *fp;
624 int error;
625
626 error = ksem_get(td, uap->id, &fp);
627 if (error)
628 return (error);
629 ks = fp->f_data;
630 if (ks->ks_flags & KS_ANONYMOUS) {
631 fdrop(fp, td);
632 return (EINVAL);
633 }
634 error = kern_close(td, uap->id);
635 fdrop(fp, td);
636 return (error);
637 }
638
639 #ifndef _SYS_SYSPROTO_H_
640 struct ksem_post_args {
641 semid_t id;
642 };
643 #endif
644 int
645 ksem_post(struct thread *td, struct ksem_post_args *uap)
646 {
647 struct file *fp;
648 struct ksem *ks;
649 int error;
650
651 error = ksem_get(td, uap->id, &fp);
652 if (error)
653 return (error);
654 ks = fp->f_data;
655
656 mtx_lock(&sem_lock);
657 #ifdef MAC
658 error = mac_posixsem_check_post(td->td_ucred, fp->f_cred, ks);
659 if (error)
660 goto err;
661 #endif
662 if (ks->ks_value == SEM_VALUE_MAX) {
663 error = EOVERFLOW;
664 goto err;
665 }
666 ++ks->ks_value;
667 if (ks->ks_waiters > 0)
668 cv_signal(&ks->ks_cv);
669 error = 0;
670 vfs_timestamp(&ks->ks_ctime);
671 err:
672 mtx_unlock(&sem_lock);
673 fdrop(fp, td);
674 return (error);
675 }
676
677 #ifndef _SYS_SYSPROTO_H_
678 struct ksem_wait_args {
679 semid_t id;
680 };
681 #endif
682 int
683 ksem_wait(struct thread *td, struct ksem_wait_args *uap)
684 {
685
686 return (kern_sem_wait(td, uap->id, 0, NULL));
687 }
688
689 #ifndef _SYS_SYSPROTO_H_
690 struct ksem_timedwait_args {
691 semid_t id;
692 const struct timespec *abstime;
693 };
694 #endif
695 int
696 ksem_timedwait(struct thread *td, struct ksem_timedwait_args *uap)
697 {
698 struct timespec abstime;
699 struct timespec *ts;
700 int error;
701
702 /*
703 * We allow a null timespec (wait forever).
704 */
705 if (uap->abstime == NULL)
706 ts = NULL;
707 else {
708 error = copyin(uap->abstime, &abstime, sizeof(abstime));
709 if (error != 0)
710 return (error);
711 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0)
712 return (EINVAL);
713 ts = &abstime;
714 }
715 return (kern_sem_wait(td, uap->id, 0, ts));
716 }
717
718 #ifndef _SYS_SYSPROTO_H_
719 struct ksem_trywait_args {
720 semid_t id;
721 };
722 #endif
723 int
724 ksem_trywait(struct thread *td, struct ksem_trywait_args *uap)
725 {
726
727 return (kern_sem_wait(td, uap->id, 1, NULL));
728 }
729
730 static int
731 kern_sem_wait(struct thread *td, semid_t id, int tryflag,
732 struct timespec *abstime)
733 {
734 struct timespec ts1, ts2;
735 struct timeval tv;
736 struct file *fp;
737 struct ksem *ks;
738 int error;
739
740 DP((">>> kern_sem_wait entered! pid=%d\n", (int)td->td_proc->p_pid));
741 error = ksem_get(td, id, &fp);
742 if (error)
743 return (error);
744 ks = fp->f_data;
745 mtx_lock(&sem_lock);
746 DP((">>> kern_sem_wait critical section entered! pid=%d\n",
747 (int)td->td_proc->p_pid));
748 #ifdef MAC
749 error = mac_posixsem_check_wait(td->td_ucred, fp->f_cred, ks);
750 if (error) {
751 DP(("kern_sem_wait mac failed\n"));
752 goto err;
753 }
754 #endif
755 DP(("kern_sem_wait value = %d, tryflag %d\n", ks->ks_value, tryflag));
756 vfs_timestamp(&ks->ks_atime);
757 while (ks->ks_value == 0) {
758 ks->ks_waiters++;
759 if (tryflag != 0)
760 error = EAGAIN;
761 else if (abstime == NULL)
762 error = cv_wait_sig(&ks->ks_cv, &sem_lock);
763 else {
764 for (;;) {
765 ts1 = *abstime;
766 getnanotime(&ts2);
767 timespecsub(&ts1, &ts2);
768 TIMESPEC_TO_TIMEVAL(&tv, &ts1);
769 if (tv.tv_sec < 0) {
770 error = ETIMEDOUT;
771 break;
772 }
773 error = cv_timedwait_sig(&ks->ks_cv,
774 &sem_lock, tvtohz(&tv));
775 if (error != EWOULDBLOCK)
776 break;
777 }
778 }
779 ks->ks_waiters--;
780 if (error)
781 goto err;
782 }
783 ks->ks_value--;
784 DP(("kern_sem_wait value post-decrement = %d\n", ks->ks_value));
785 error = 0;
786 err:
787 mtx_unlock(&sem_lock);
788 fdrop(fp, td);
789 DP(("<<< kern_sem_wait leaving, pid=%d, error = %d\n",
790 (int)td->td_proc->p_pid, error));
791 return (error);
792 }
793
794 #ifndef _SYS_SYSPROTO_H_
795 struct ksem_getvalue_args {
796 semid_t id;
797 int *val;
798 };
799 #endif
800 int
801 ksem_getvalue(struct thread *td, struct ksem_getvalue_args *uap)
802 {
803 struct file *fp;
804 struct ksem *ks;
805 int error, val;
806
807 error = ksem_get(td, uap->id, &fp);
808 if (error)
809 return (error);
810 ks = fp->f_data;
811
812 mtx_lock(&sem_lock);
813 #ifdef MAC
814 error = mac_posixsem_check_getvalue(td->td_ucred, fp->f_cred, ks);
815 if (error) {
816 mtx_unlock(&sem_lock);
817 fdrop(fp, td);
818 return (error);
819 }
820 #endif
821 val = ks->ks_value;
822 vfs_timestamp(&ks->ks_atime);
823 mtx_unlock(&sem_lock);
824 fdrop(fp, td);
825 error = copyout(&val, uap->val, sizeof(val));
826 return (error);
827 }
828
829 #ifndef _SYS_SYSPROTO_H_
830 struct ksem_destroy_args {
831 semid_t id;
832 };
833 #endif
834 int
835 ksem_destroy(struct thread *td, struct ksem_destroy_args *uap)
836 {
837 struct file *fp;
838 struct ksem *ks;
839 int error;
840
841 error = ksem_get(td, uap->id, &fp);
842 if (error)
843 return (error);
844 ks = fp->f_data;
845 if (!(ks->ks_flags & KS_ANONYMOUS)) {
846 fdrop(fp, td);
847 return (EINVAL);
848 }
849 mtx_lock(&sem_lock);
850 if (ks->ks_waiters != 0) {
851 mtx_unlock(&sem_lock);
852 error = EBUSY;
853 goto err;
854 }
855 ks->ks_flags |= KS_DEAD;
856 mtx_unlock(&sem_lock);
857
858 error = kern_close(td, uap->id);
859 err:
860 fdrop(fp, td);
861 return (error);
862 }
863
864 static struct syscall_helper_data ksem_syscalls[] = {
865 SYSCALL_INIT_HELPER(ksem_init),
866 SYSCALL_INIT_HELPER(ksem_open),
867 SYSCALL_INIT_HELPER(ksem_unlink),
868 SYSCALL_INIT_HELPER(ksem_close),
869 SYSCALL_INIT_HELPER(ksem_post),
870 SYSCALL_INIT_HELPER(ksem_wait),
871 SYSCALL_INIT_HELPER(ksem_timedwait),
872 SYSCALL_INIT_HELPER(ksem_trywait),
873 SYSCALL_INIT_HELPER(ksem_getvalue),
874 SYSCALL_INIT_HELPER(ksem_destroy),
875 SYSCALL_INIT_LAST
876 };
877
878 #ifdef COMPAT_FREEBSD32
879 #include <compat/freebsd32/freebsd32.h>
880 #include <compat/freebsd32/freebsd32_proto.h>
881 #include <compat/freebsd32/freebsd32_signal.h>
882 #include <compat/freebsd32/freebsd32_syscall.h>
883 #include <compat/freebsd32/freebsd32_util.h>
884
885 int
886 freebsd32_ksem_init(struct thread *td, struct freebsd32_ksem_init_args *uap)
887 {
888
889 return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value,
890 0, 1));
891 }
892
893 int
894 freebsd32_ksem_open(struct thread *td, struct freebsd32_ksem_open_args *uap)
895 {
896
897 if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0)
898 return (EINVAL);
899 return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value,
900 uap->oflag, 1));
901 }
902
903 int
904 freebsd32_ksem_timedwait(struct thread *td,
905 struct freebsd32_ksem_timedwait_args *uap)
906 {
907 struct timespec32 abstime32;
908 struct timespec *ts, abstime;
909 int error;
910
911 /*
912 * We allow a null timespec (wait forever).
913 */
914 if (uap->abstime == NULL)
915 ts = NULL;
916 else {
917 error = copyin(uap->abstime, &abstime32, sizeof(abstime32));
918 if (error != 0)
919 return (error);
920 CP(abstime32, abstime, tv_sec);
921 CP(abstime32, abstime, tv_nsec);
922 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0)
923 return (EINVAL);
924 ts = &abstime;
925 }
926 return (kern_sem_wait(td, uap->id, 0, ts));
927 }
928
929 static struct syscall_helper_data ksem32_syscalls[] = {
930 SYSCALL32_INIT_HELPER(freebsd32_ksem_init),
931 SYSCALL32_INIT_HELPER(freebsd32_ksem_open),
932 SYSCALL32_INIT_HELPER(ksem_unlink),
933 SYSCALL32_INIT_HELPER(ksem_close),
934 SYSCALL32_INIT_HELPER(ksem_post),
935 SYSCALL32_INIT_HELPER(ksem_wait),
936 SYSCALL32_INIT_HELPER(freebsd32_ksem_timedwait),
937 SYSCALL32_INIT_HELPER(ksem_trywait),
938 SYSCALL32_INIT_HELPER(ksem_getvalue),
939 SYSCALL32_INIT_HELPER(ksem_destroy),
940 SYSCALL_INIT_LAST
941 };
942 #endif
943
944 static int
945 ksem_module_init(void)
946 {
947 int error;
948
949 mtx_init(&sem_lock, "sem", NULL, MTX_DEF);
950 mtx_init(&ksem_count_lock, "ksem count", NULL, MTX_DEF);
951 sx_init(&ksem_dict_lock, "ksem dictionary");
952 ksem_dictionary = hashinit(1024, M_KSEM, &ksem_hash);
953 p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 200112L);
954 p31b_setcfg(CTL_P1003_1B_SEM_NSEMS_MAX, SEM_MAX);
955 p31b_setcfg(CTL_P1003_1B_SEM_VALUE_MAX, SEM_VALUE_MAX);
956
957 error = syscall_helper_register(ksem_syscalls);
958 if (error)
959 return (error);
960 #ifdef COMPAT_FREEBSD32
961 error = syscall32_helper_register(ksem32_syscalls);
962 if (error)
963 return (error);
964 #endif
965 return (0);
966 }
967
968 static void
969 ksem_module_destroy(void)
970 {
971
972 #ifdef COMPAT_FREEBSD32
973 syscall32_helper_unregister(ksem32_syscalls);
974 #endif
975 syscall_helper_unregister(ksem_syscalls);
976
977 p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 0);
978 hashdestroy(ksem_dictionary, M_KSEM, ksem_hash);
979 sx_destroy(&ksem_dict_lock);
980 mtx_destroy(&ksem_count_lock);
981 mtx_destroy(&sem_lock);
982 p31b_unsetcfg(CTL_P1003_1B_SEM_VALUE_MAX);
983 p31b_unsetcfg(CTL_P1003_1B_SEM_NSEMS_MAX);
984 }
985
986 static int
987 sem_modload(struct module *module, int cmd, void *arg)
988 {
989 int error = 0;
990
991 switch (cmd) {
992 case MOD_LOAD:
993 error = ksem_module_init();
994 if (error)
995 ksem_module_destroy();
996 break;
997
998 case MOD_UNLOAD:
999 mtx_lock(&ksem_count_lock);
1000 if (nsems != 0) {
1001 error = EOPNOTSUPP;
1002 mtx_unlock(&ksem_count_lock);
1003 break;
1004 }
1005 ksem_dead = 1;
1006 mtx_unlock(&ksem_count_lock);
1007 ksem_module_destroy();
1008 break;
1009
1010 case MOD_SHUTDOWN:
1011 break;
1012 default:
1013 error = EINVAL;
1014 break;
1015 }
1016 return (error);
1017 }
1018
1019 static moduledata_t sem_mod = {
1020 "sem",
1021 &sem_modload,
1022 NULL
1023 };
1024
1025 DECLARE_MODULE(sem, sem_mod, SI_SUB_SYSV_SEM, SI_ORDER_FIRST);
1026 MODULE_VERSION(sem, 1);
Cache object: 2111cbee42836199af85ea3893313c90
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