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
--- 18 unchanged lines hidden (view full) ---
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: head/sys/kern/uipc_sem.c 180059 2008-06-27 05:39:04Z jhb $");
36
37#include "opt_mac.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
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);
118static void ksem_drop(struct ksem *ks);
119static int ksem_get(struct thread *td, semid_t id, struct file **fpp);
120static struct ksem *ksem_hold(struct ksem *ks);
121static void ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks);
122static struct ksem *ksem_lookup(char *path, Fnv32_t fnv);
123static void ksem_module_destroy(void);
124static int ksem_module_init(void);
125static int ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred);
126static int sem_modload(struct module *module, int cmd, void *arg);
127
128static fo_rdwr_t ksem_read;
129static fo_rdwr_t ksem_write;
130static fo_truncate_t ksem_truncate;
131static fo_ioctl_t ksem_ioctl;
132static fo_poll_t ksem_poll;
133static fo_kqfilter_t ksem_kqfilter;
134static fo_stat_t ksem_stat;
135static fo_close_t ksem_closef;
136
137/* File descriptor operations. */
138static 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
150FEATURE(posix_sem, "POSIX semaphores");
151
152static int
153ksem_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
154 int flags, struct thread *td)
155{
156
157 return (EOPNOTSUPP);
158}
159
160static int
161ksem_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
162 int flags, struct thread *td)
163{
164
165 return (EOPNOTSUPP);
166}
167
168static int
169ksem_truncate(struct file *fp, off_t length, struct ucred *active_cred,
170 struct thread *td)
171{
172
173 return (EINVAL);
174}
175
176static int
177ksem_ioctl(struct file *fp, u_long com, void *data,
178 struct ucred *active_cred, struct thread *td)
179{
180
181 return (EOPNOTSUPP);
182}
183
184static int
185ksem_poll(struct file *fp, int events, struct ucred *active_cred,
186 struct thread *td)
187{
188
189 return (EOPNOTSUPP);
190}
191
192static int
193ksem_kqfilter(struct file *fp, struct knote *kn)
194{
195
196 return (EOPNOTSUPP);
197}
198
199static int
200ksem_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
233static int
234ksem_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 */
249static struct ksem *
250ksem_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
278static struct ksem *
279ksem_hold(struct ksem *ks)
280{
281
282 refcount_acquire(&ks->ks_ref);
283 return (ks);
284}
285
286static void
287ksem_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 */
306static int
307ksem_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 */
323static struct ksem *
324ksem_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
338static void
339ksem_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
350static int
351ksem_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/* Other helper routines. */
380static int
381ksem_create(struct thread *td, const char *name, semid_t *semidp, mode_t mode,
382 unsigned int value, int flags)
383{
384 struct filedesc *fdp;
385 struct ksem *ks;
386 struct file *fp;
387 char *path;
388 semid_t semid;
389 Fnv32_t fnv;
390 int error, fd;
391
392 if (value > SEM_VALUE_MAX)
393 return (EINVAL);
394
395 fdp = td->td_proc->p_fd;
396 mode = (mode & ~fdp->fd_cmask) & ACCESSPERMS;
397 error = falloc(td, &fp, &fd);
398 if (error) {
399 if (name == NULL)
400 error = ENOSPC;
401 return (error);
402 }
403
404 /*
405 * Go ahead and copyout the file descriptor now. This is a bit
406 * premature, but it is a lot easier to handle errors as opposed
407 * to later when we've possibly created a new semaphore, etc.
408 */
409 semid = fd;
410 error = copyout(&semid, semidp, sizeof(semid));
411 if (error) {
412 fdclose(fdp, fp, fd, td);
413 fdrop(fp, td);
414 return (error);
415 }
416
417 if (name == NULL) {
418 /* Create an anonymous semaphore. */
419 ks = ksem_alloc(td->td_ucred, mode, value);
420 if (ks == NULL)
421 error = ENOSPC;
422 else
423 ks->ks_flags |= KS_ANONYMOUS;
424 } else {
425 path = malloc(MAXPATHLEN, M_KSEM, M_WAITOK);
426 error = copyinstr(name, path, MAXPATHLEN, NULL);
427
428 /* Require paths to start with a '/' character. */
429 if (error == 0 && path[0] != '/')
430 error = EINVAL;
431 if (error) {
432 fdclose(fdp, fp, fd, td);
433 fdrop(fp, td);
434 free(path, M_KSEM);
435 return (error);
436 }
437
438 fnv = fnv_32_str(path, FNV1_32_INIT);
439 sx_xlock(&ksem_dict_lock);
440 ks = ksem_lookup(path, fnv);
441 if (ks == NULL) {
442 /* Object does not exist, create it if requested. */
443 if (flags & O_CREAT) {
444 ks = ksem_alloc(td->td_ucred, mode, value);
445 if (ks == NULL)
446 error = ENFILE;
447 else {
448 ksem_insert(path, fnv, ks);
449 path = NULL;
450 }
451 } else
452 error = ENOENT;
453 } else {
454 /*
455 * Object already exists, obtain a new
456 * reference if requested and permitted.
457 */
458 if ((flags & (O_CREAT | O_EXCL)) ==
459 (O_CREAT | O_EXCL))
460 error = EEXIST;
461 else {
462#ifdef MAC
463 error = mac_posixsem_check_open(td->td_ucred,
464 ks);
465 if (error == 0)
466#endif
467 error = ksem_access(ks, td->td_ucred);
468 }
469 if (error == 0)
470 ksem_hold(ks);
471#ifdef INVARIANTS
472 else
473 ks = NULL;
474#endif
475 }
476 sx_xunlock(&ksem_dict_lock);
477 if (path)
478 free(path, M_KSEM);
479 }
480
481 if (error) {
482 KASSERT(ks == NULL, ("ksem_create error with a ksem"));
483 fdclose(fdp, fp, fd, td);
484 fdrop(fp, td);
485 return (error);
486 }
487 KASSERT(ks != NULL, ("ksem_create w/o a ksem"));
488
489 finit(fp, FREAD | FWRITE, DTYPE_SEM, ks, &ksem_ops);
490
491 FILEDESC_XLOCK(fdp);
492 if (fdp->fd_ofiles[fd] == fp)
493 fdp->fd_ofileflags[fd] |= UF_EXCLOSE;
494 FILEDESC_XUNLOCK(fdp);
495 fdrop(fp, td);
496
497 return (0);
498}
499
500static int
501ksem_get(struct thread *td, semid_t id, struct file **fpp)
502{
503 struct ksem *ks;
504 struct file *fp;
505 int error;
506
507 error = fget(td, id, &fp);
508 if (error)
509 return (EINVAL);
510 if (fp->f_type != DTYPE_SEM) {
511 fdrop(fp, td);
512 return (EINVAL);
513 }
514 ks = fp->f_data;
515 if (ks->ks_flags & KS_DEAD) {
516 fdrop(fp, td);
517 return (EINVAL);
518 }
519 *fpp = fp;
520 return (0);
521}
522
523/* System calls. */
524#ifndef _SYS_SYSPROTO_H_
525struct ksem_init_args {
526 unsigned int value;
527 semid_t *idp;
528};
529#endif
530int
531ksem_init(struct thread *td, struct ksem_init_args *uap)
532{
533
534 return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value,
535 0));
536}
537
538#ifndef _SYS_SYSPROTO_H_
539struct ksem_open_args {
540 char *name;
541 int oflag;
542 mode_t mode;
543 unsigned int value;
544 semid_t *idp;
545};
546#endif
547int
548ksem_open(struct thread *td, struct ksem_open_args *uap)
549{
550
551 if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0)
552 return (EINVAL);
553 return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value,
554 uap->oflag));
555}
556
557#ifndef _SYS_SYSPROTO_H_
558struct ksem_unlink_args {
559 char *name;
560};
561#endif
562int
563ksem_unlink(struct thread *td, struct ksem_unlink_args *uap)
564{
565 char *path;
566 Fnv32_t fnv;
567 int error;
568
569 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
570 error = copyinstr(uap->name, path, MAXPATHLEN, NULL);
571 if (error) {
572 free(path, M_TEMP);
573 return (error);
574 }
575
576 fnv = fnv_32_str(path, FNV1_32_INIT);
577 sx_xlock(&ksem_dict_lock);
578 error = ksem_remove(path, fnv, td->td_ucred);
579 sx_xunlock(&ksem_dict_lock);
580 free(path, M_TEMP);
581
582 return (error);
583}
584
585#ifndef _SYS_SYSPROTO_H_
586struct ksem_close_args {
587 semid_t id;
588};
589#endif
590int
591ksem_close(struct thread *td, struct ksem_close_args *uap)
592{
593 struct ksem *ks;
594 struct file *fp;
595 int error;
596
597 error = ksem_get(td, uap->id, &fp);
598 if (error)
599 return (error);
600 ks = fp->f_data;
601 if (ks->ks_flags & KS_ANONYMOUS) {
602 fdrop(fp, td);
603 return (EINVAL);
604 }
605 error = kern_close(td, uap->id);
606 fdrop(fp, td);
607 return (error);
608}
609
610#ifndef _SYS_SYSPROTO_H_
611struct ksem_post_args {
612 semid_t id;
613};
614#endif
615int
616ksem_post(struct thread *td, struct ksem_post_args *uap)
617{
618 struct file *fp;
619 struct ksem *ks;
620 int error;
621
622 error = ksem_get(td, uap->id, &fp);
623 if (error)
624 return (error);
625 ks = fp->f_data;
626
627 mtx_lock(&sem_lock);
628#ifdef MAC
629 error = mac_posixsem_check_post(td->td_ucred, fp->f_cred, ks);
630 if (error)
631 goto err;
632#endif
633 if (ks->ks_value == SEM_VALUE_MAX) {
634 error = EOVERFLOW;
635 goto err;
636 }
637 ++ks->ks_value;
638 if (ks->ks_waiters > 0)
639 cv_signal(&ks->ks_cv);
640 error = 0;
641 vfs_timestamp(&ks->ks_ctime);
642err:
643 mtx_unlock(&sem_lock);
644 fdrop(fp, td);
645 return (error);
646}
647
648#ifndef _SYS_SYSPROTO_H_
649struct ksem_wait_args {
650 semid_t id;
651};
652#endif
653int
654ksem_wait(struct thread *td, struct ksem_wait_args *uap)
655{
656
657 return (kern_sem_wait(td, uap->id, 0, NULL));
658}
659
660#ifndef _SYS_SYSPROTO_H_
661struct ksem_timedwait_args {
662 semid_t id;
663 const struct timespec *abstime;
664};
665#endif
666int
667ksem_timedwait(struct thread *td, struct ksem_timedwait_args *uap)
668{
669 struct timespec abstime;
670 struct timespec *ts;
671 int error;
672
--- 10 unchanged lines hidden (view full) ---
683 return (EINVAL);
684 ts = &abstime;
685 }
686 return (kern_sem_wait(td, uap->id, 0, ts));
687}
688
689#ifndef _SYS_SYSPROTO_H_
690struct ksem_trywait_args {
691 semid_t id;
692};
693#endif
694int
695ksem_trywait(struct thread *td, struct ksem_trywait_args *uap)
696{
697
698 return (kern_sem_wait(td, uap->id, 1, NULL));
699}
700
701static int
702kern_sem_wait(struct thread *td, semid_t id, int tryflag,
703 struct timespec *abstime)
704{
705 struct timespec ts1, ts2;
706 struct timeval tv;
707 struct file *fp;
708 struct ksem *ks;
709 int error;
710
711 DP((">>> kern_sem_wait entered!\n"));
712 error = ksem_get(td, id, &fp);
713 if (error)
714 return (error);
715 ks = fp->f_data;
716 mtx_lock(&sem_lock);
717#ifdef MAC
718 error = mac_posixsem_check_wait(td->td_ucred, fp->f_cred, ks);
719 if (error) {
720 DP(("kern_sem_wait mac failed\n"));
721 goto err;
722 }
723#endif
724 DP(("kern_sem_wait value = %d, tryflag %d\n", ks->ks_value, tryflag));
725 vfs_timestamp(&ks->ks_atime);
726 if (ks->ks_value == 0) {
727 ks->ks_waiters++;
728 if (tryflag != 0)
729 error = EAGAIN;
730 else if (abstime == NULL)
731 error = cv_wait_sig(&ks->ks_cv, &sem_lock);
732 else {
733 for (;;) {
--- 13 unchanged lines hidden (view full) ---
747 }
748 ks->ks_waiters--;
749 if (error)
750 goto err;
751 }
752 ks->ks_value--;
753 error = 0;
754err:
755 mtx_unlock(&sem_lock);
756 fdrop(fp, td);
757 DP(("<<< kern_sem_wait leaving, error = %d\n", error));
758 return (error);
759}
760
761#ifndef _SYS_SYSPROTO_H_
762struct ksem_getvalue_args {
763 semid_t id;
764 int *val;
765};
766#endif
767int
768ksem_getvalue(struct thread *td, struct ksem_getvalue_args *uap)
769{
770 struct file *fp;
771 struct ksem *ks;
772 int error, val;
773
774 error = ksem_get(td, uap->id, &fp);
775 if (error)
776 return (error);
777 ks = fp->f_data;
778
779 mtx_lock(&sem_lock);
780#ifdef MAC
781 error = mac_posixsem_check_getvalue(td->td_ucred, fp->f_cred, ks);
782 if (error) {
783 mtx_unlock(&sem_lock);
784 fdrop(fp, td);
785 return (error);
786 }
787#endif
788 val = ks->ks_value;
789 vfs_timestamp(&ks->ks_atime);
790 mtx_unlock(&sem_lock);
791 fdrop(fp, td);
792 error = copyout(&val, uap->val, sizeof(val));
793 return (error);
794}
795
796#ifndef _SYS_SYSPROTO_H_
797struct ksem_destroy_args {
798 semid_t id;
799};
800#endif
801int
802ksem_destroy(struct thread *td, struct ksem_destroy_args *uap)
803{
804 struct file *fp;
805 struct ksem *ks;
806 int error;
807
808 error = ksem_get(td, uap->id, &fp);
809 if (error)
810 return (error);
811 ks = fp->f_data;
812 if (!(ks->ks_flags & KS_ANONYMOUS)) {
813 fdrop(fp, td);
814 return (EINVAL);
815 }
816 mtx_lock(&sem_lock);
817 if (ks->ks_waiters != 0) {
818 mtx_unlock(&sem_lock);
819 error = EBUSY;
820 goto err;
821 }
822 ks->ks_flags |= KS_DEAD;
823 mtx_unlock(&sem_lock);
824
825 error = kern_close(td, uap->id);
826err:
827 fdrop(fp, td);
828 return (error);
829}
830
831#define SYSCALL_DATA(syscallname) \
832static int syscallname##_syscall = SYS_##syscallname; \
833static int syscallname##_registered; \
834static struct sysent syscallname##_old_sysent; \
835MAKE_SYSENT(syscallname);
836
837#define SYSCALL_REGISTER(syscallname) do { \
838 error = syscall_register(& syscallname##_syscall, \
839 & syscallname##_sysent, & syscallname##_old_sysent); \
840 if (error) \
841 return (error); \
842 syscallname##_registered = 1; \
843} while(0)
844
845#define SYSCALL_DEREGISTER(syscallname) do { \
846 if (syscallname##_registered) { \
847 syscallname##_registered = 0; \
848 syscall_deregister(& syscallname##_syscall, \
849 & syscallname##_old_sysent); \
850 } \
851} while(0)
852
853SYSCALL_DATA(ksem_init);
854SYSCALL_DATA(ksem_open);
855SYSCALL_DATA(ksem_unlink);
856SYSCALL_DATA(ksem_close);
857SYSCALL_DATA(ksem_post);
858SYSCALL_DATA(ksem_wait);
859SYSCALL_DATA(ksem_timedwait);
860SYSCALL_DATA(ksem_trywait);
861SYSCALL_DATA(ksem_getvalue);
862SYSCALL_DATA(ksem_destroy);
863
864static int
865ksem_module_init(void)
866{
867 int error;
868
869 mtx_init(&sem_lock, "sem", NULL, MTX_DEF);
870 mtx_init(&ksem_count_lock, "ksem count", NULL, MTX_DEF);
871 sx_init(&ksem_dict_lock, "ksem dictionary");
872 ksem_dictionary = hashinit(1024, M_KSEM, &ksem_hash);
873 p31b_setcfg(CTL_P1003_1B_SEM_NSEMS_MAX, SEM_MAX);
874 p31b_setcfg(CTL_P1003_1B_SEM_VALUE_MAX, SEM_VALUE_MAX);
875
876 SYSCALL_REGISTER(ksem_init);
877 SYSCALL_REGISTER(ksem_open);
878 SYSCALL_REGISTER(ksem_unlink);
879 SYSCALL_REGISTER(ksem_close);
880 SYSCALL_REGISTER(ksem_post);
881 SYSCALL_REGISTER(ksem_wait);
882 SYSCALL_REGISTER(ksem_timedwait);
883 SYSCALL_REGISTER(ksem_trywait);
884 SYSCALL_REGISTER(ksem_getvalue);
885 SYSCALL_REGISTER(ksem_destroy);
886 return (0);
887}
888
889static void
890ksem_module_destroy(void)
891{
892
893 SYSCALL_DEREGISTER(ksem_init);
894 SYSCALL_DEREGISTER(ksem_open);
895 SYSCALL_DEREGISTER(ksem_unlink);
896 SYSCALL_DEREGISTER(ksem_close);
897 SYSCALL_DEREGISTER(ksem_post);
898 SYSCALL_DEREGISTER(ksem_wait);
899 SYSCALL_DEREGISTER(ksem_timedwait);
900 SYSCALL_DEREGISTER(ksem_trywait);
901 SYSCALL_DEREGISTER(ksem_getvalue);
902 SYSCALL_DEREGISTER(ksem_destroy);
903
904 hashdestroy(ksem_dictionary, M_KSEM, ksem_hash);
905 sx_destroy(&ksem_dict_lock);
906 mtx_destroy(&ksem_count_lock);
907 mtx_destroy(&sem_lock);
908}
909
910static int
911sem_modload(struct module *module, int cmd, void *arg)
912{
913 int error = 0;
914
915 switch (cmd) {
916 case MOD_LOAD:
917 error = ksem_module_init();
918 if (error)
919 ksem_module_destroy();
920 break;
921
922 case MOD_UNLOAD:
923 mtx_lock(&ksem_count_lock);
924 if (nsems != 0) {
925 error = EOPNOTSUPP;
926 mtx_unlock(&ksem_count_lock);
927 break;
928 }
929 ksem_dead = 1;
930 mtx_unlock(&ksem_count_lock);
931 ksem_module_destroy();
932 break;
933
934 case MOD_SHUTDOWN:
935 break;
936 default:
937 error = EINVAL;
938 break;
939 }
940 return (error);
941}
942
943static moduledata_t sem_mod = {
944 "sem",
945 &sem_modload,
946 NULL
947};
948
949DECLARE_MODULE(sem, sem_mod, SI_SUB_SYSV_SEM, SI_ORDER_FIRST);
950MODULE_VERSION(sem, 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
--- 18 unchanged lines hidden (view full) ---
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: head/sys/kern/uipc_sem.c 180059 2008-06-27 05:39:04Z jhb $");
36
37#include "opt_mac.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
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);
118static void ksem_drop(struct ksem *ks);
119static int ksem_get(struct thread *td, semid_t id, struct file **fpp);
120static struct ksem *ksem_hold(struct ksem *ks);
121static void ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks);
122static struct ksem *ksem_lookup(char *path, Fnv32_t fnv);
123static void ksem_module_destroy(void);
124static int ksem_module_init(void);
125static int ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred);
126static int sem_modload(struct module *module, int cmd, void *arg);
127
128static fo_rdwr_t ksem_read;
129static fo_rdwr_t ksem_write;
130static fo_truncate_t ksem_truncate;
131static fo_ioctl_t ksem_ioctl;
132static fo_poll_t ksem_poll;
133static fo_kqfilter_t ksem_kqfilter;
134static fo_stat_t ksem_stat;
135static fo_close_t ksem_closef;
136
137/* File descriptor operations. */
138static 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
150FEATURE(posix_sem, "POSIX semaphores");
151
152static int
153ksem_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
154 int flags, struct thread *td)
155{
156
157 return (EOPNOTSUPP);
158}
159
160static int
161ksem_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
162 int flags, struct thread *td)
163{
164
165 return (EOPNOTSUPP);
166}
167
168static int
169ksem_truncate(struct file *fp, off_t length, struct ucred *active_cred,
170 struct thread *td)
171{
172
173 return (EINVAL);
174}
175
176static int
177ksem_ioctl(struct file *fp, u_long com, void *data,
178 struct ucred *active_cred, struct thread *td)
179{
180
181 return (EOPNOTSUPP);
182}
183
184static int
185ksem_poll(struct file *fp, int events, struct ucred *active_cred,
186 struct thread *td)
187{
188
189 return (EOPNOTSUPP);
190}
191
192static int
193ksem_kqfilter(struct file *fp, struct knote *kn)
194{
195
196 return (EOPNOTSUPP);
197}
198
199static int
200ksem_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
233static int
234ksem_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 */
249static struct ksem *
250ksem_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
278static struct ksem *
279ksem_hold(struct ksem *ks)
280{
281
282 refcount_acquire(&ks->ks_ref);
283 return (ks);
284}
285
286static void
287ksem_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 */
306static int
307ksem_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 */
323static struct ksem *
324ksem_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
338static void
339ksem_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
350static int
351ksem_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/* Other helper routines. */
380static int
381ksem_create(struct thread *td, const char *name, semid_t *semidp, mode_t mode,
382 unsigned int value, int flags)
383{
384 struct filedesc *fdp;
385 struct ksem *ks;
386 struct file *fp;
387 char *path;
388 semid_t semid;
389 Fnv32_t fnv;
390 int error, fd;
391
392 if (value > SEM_VALUE_MAX)
393 return (EINVAL);
394
395 fdp = td->td_proc->p_fd;
396 mode = (mode & ~fdp->fd_cmask) & ACCESSPERMS;
397 error = falloc(td, &fp, &fd);
398 if (error) {
399 if (name == NULL)
400 error = ENOSPC;
401 return (error);
402 }
403
404 /*
405 * Go ahead and copyout the file descriptor now. This is a bit
406 * premature, but it is a lot easier to handle errors as opposed
407 * to later when we've possibly created a new semaphore, etc.
408 */
409 semid = fd;
410 error = copyout(&semid, semidp, sizeof(semid));
411 if (error) {
412 fdclose(fdp, fp, fd, td);
413 fdrop(fp, td);
414 return (error);
415 }
416
417 if (name == NULL) {
418 /* Create an anonymous semaphore. */
419 ks = ksem_alloc(td->td_ucred, mode, value);
420 if (ks == NULL)
421 error = ENOSPC;
422 else
423 ks->ks_flags |= KS_ANONYMOUS;
424 } else {
425 path = malloc(MAXPATHLEN, M_KSEM, M_WAITOK);
426 error = copyinstr(name, path, MAXPATHLEN, NULL);
427
428 /* Require paths to start with a '/' character. */
429 if (error == 0 && path[0] != '/')
430 error = EINVAL;
431 if (error) {
432 fdclose(fdp, fp, fd, td);
433 fdrop(fp, td);
434 free(path, M_KSEM);
435 return (error);
436 }
437
438 fnv = fnv_32_str(path, FNV1_32_INIT);
439 sx_xlock(&ksem_dict_lock);
440 ks = ksem_lookup(path, fnv);
441 if (ks == NULL) {
442 /* Object does not exist, create it if requested. */
443 if (flags & O_CREAT) {
444 ks = ksem_alloc(td->td_ucred, mode, value);
445 if (ks == NULL)
446 error = ENFILE;
447 else {
448 ksem_insert(path, fnv, ks);
449 path = NULL;
450 }
451 } else
452 error = ENOENT;
453 } else {
454 /*
455 * Object already exists, obtain a new
456 * reference if requested and permitted.
457 */
458 if ((flags & (O_CREAT | O_EXCL)) ==
459 (O_CREAT | O_EXCL))
460 error = EEXIST;
461 else {
462#ifdef MAC
463 error = mac_posixsem_check_open(td->td_ucred,
464 ks);
465 if (error == 0)
466#endif
467 error = ksem_access(ks, td->td_ucred);
468 }
469 if (error == 0)
470 ksem_hold(ks);
471#ifdef INVARIANTS
472 else
473 ks = NULL;
474#endif
475 }
476 sx_xunlock(&ksem_dict_lock);
477 if (path)
478 free(path, M_KSEM);
479 }
480
481 if (error) {
482 KASSERT(ks == NULL, ("ksem_create error with a ksem"));
483 fdclose(fdp, fp, fd, td);
484 fdrop(fp, td);
485 return (error);
486 }
487 KASSERT(ks != NULL, ("ksem_create w/o a ksem"));
488
489 finit(fp, FREAD | FWRITE, DTYPE_SEM, ks, &ksem_ops);
490
491 FILEDESC_XLOCK(fdp);
492 if (fdp->fd_ofiles[fd] == fp)
493 fdp->fd_ofileflags[fd] |= UF_EXCLOSE;
494 FILEDESC_XUNLOCK(fdp);
495 fdrop(fp, td);
496
497 return (0);
498}
499
500static int
501ksem_get(struct thread *td, semid_t id, struct file **fpp)
502{
503 struct ksem *ks;
504 struct file *fp;
505 int error;
506
507 error = fget(td, id, &fp);
508 if (error)
509 return (EINVAL);
510 if (fp->f_type != DTYPE_SEM) {
511 fdrop(fp, td);
512 return (EINVAL);
513 }
514 ks = fp->f_data;
515 if (ks->ks_flags & KS_DEAD) {
516 fdrop(fp, td);
517 return (EINVAL);
518 }
519 *fpp = fp;
520 return (0);
521}
522
523/* System calls. */
524#ifndef _SYS_SYSPROTO_H_
525struct ksem_init_args {
526 unsigned int value;
527 semid_t *idp;
528};
529#endif
530int
531ksem_init(struct thread *td, struct ksem_init_args *uap)
532{
533
534 return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value,
535 0));
536}
537
538#ifndef _SYS_SYSPROTO_H_
539struct ksem_open_args {
540 char *name;
541 int oflag;
542 mode_t mode;
543 unsigned int value;
544 semid_t *idp;
545};
546#endif
547int
548ksem_open(struct thread *td, struct ksem_open_args *uap)
549{
550
551 if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0)
552 return (EINVAL);
553 return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value,
554 uap->oflag));
555}
556
557#ifndef _SYS_SYSPROTO_H_
558struct ksem_unlink_args {
559 char *name;
560};
561#endif
562int
563ksem_unlink(struct thread *td, struct ksem_unlink_args *uap)
564{
565 char *path;
566 Fnv32_t fnv;
567 int error;
568
569 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
570 error = copyinstr(uap->name, path, MAXPATHLEN, NULL);
571 if (error) {
572 free(path, M_TEMP);
573 return (error);
574 }
575
576 fnv = fnv_32_str(path, FNV1_32_INIT);
577 sx_xlock(&ksem_dict_lock);
578 error = ksem_remove(path, fnv, td->td_ucred);
579 sx_xunlock(&ksem_dict_lock);
580 free(path, M_TEMP);
581
582 return (error);
583}
584
585#ifndef _SYS_SYSPROTO_H_
586struct ksem_close_args {
587 semid_t id;
588};
589#endif
590int
591ksem_close(struct thread *td, struct ksem_close_args *uap)
592{
593 struct ksem *ks;
594 struct file *fp;
595 int error;
596
597 error = ksem_get(td, uap->id, &fp);
598 if (error)
599 return (error);
600 ks = fp->f_data;
601 if (ks->ks_flags & KS_ANONYMOUS) {
602 fdrop(fp, td);
603 return (EINVAL);
604 }
605 error = kern_close(td, uap->id);
606 fdrop(fp, td);
607 return (error);
608}
609
610#ifndef _SYS_SYSPROTO_H_
611struct ksem_post_args {
612 semid_t id;
613};
614#endif
615int
616ksem_post(struct thread *td, struct ksem_post_args *uap)
617{
618 struct file *fp;
619 struct ksem *ks;
620 int error;
621
622 error = ksem_get(td, uap->id, &fp);
623 if (error)
624 return (error);
625 ks = fp->f_data;
626
627 mtx_lock(&sem_lock);
628#ifdef MAC
629 error = mac_posixsem_check_post(td->td_ucred, fp->f_cred, ks);
630 if (error)
631 goto err;
632#endif
633 if (ks->ks_value == SEM_VALUE_MAX) {
634 error = EOVERFLOW;
635 goto err;
636 }
637 ++ks->ks_value;
638 if (ks->ks_waiters > 0)
639 cv_signal(&ks->ks_cv);
640 error = 0;
641 vfs_timestamp(&ks->ks_ctime);
642err:
643 mtx_unlock(&sem_lock);
644 fdrop(fp, td);
645 return (error);
646}
647
648#ifndef _SYS_SYSPROTO_H_
649struct ksem_wait_args {
650 semid_t id;
651};
652#endif
653int
654ksem_wait(struct thread *td, struct ksem_wait_args *uap)
655{
656
657 return (kern_sem_wait(td, uap->id, 0, NULL));
658}
659
660#ifndef _SYS_SYSPROTO_H_
661struct ksem_timedwait_args {
662 semid_t id;
663 const struct timespec *abstime;
664};
665#endif
666int
667ksem_timedwait(struct thread *td, struct ksem_timedwait_args *uap)
668{
669 struct timespec abstime;
670 struct timespec *ts;
671 int error;
672
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683 return (EINVAL);
684 ts = &abstime;
685 }
686 return (kern_sem_wait(td, uap->id, 0, ts));
687}
688
689#ifndef _SYS_SYSPROTO_H_
690struct ksem_trywait_args {
691 semid_t id;
692};
693#endif
694int
695ksem_trywait(struct thread *td, struct ksem_trywait_args *uap)
696{
697
698 return (kern_sem_wait(td, uap->id, 1, NULL));
699}
700
701static int
702kern_sem_wait(struct thread *td, semid_t id, int tryflag,
703 struct timespec *abstime)
704{
705 struct timespec ts1, ts2;
706 struct timeval tv;
707 struct file *fp;
708 struct ksem *ks;
709 int error;
710
711 DP((">>> kern_sem_wait entered!\n"));
712 error = ksem_get(td, id, &fp);
713 if (error)
714 return (error);
715 ks = fp->f_data;
716 mtx_lock(&sem_lock);
717#ifdef MAC
718 error = mac_posixsem_check_wait(td->td_ucred, fp->f_cred, ks);
719 if (error) {
720 DP(("kern_sem_wait mac failed\n"));
721 goto err;
722 }
723#endif
724 DP(("kern_sem_wait value = %d, tryflag %d\n", ks->ks_value, tryflag));
725 vfs_timestamp(&ks->ks_atime);
726 if (ks->ks_value == 0) {
727 ks->ks_waiters++;
728 if (tryflag != 0)
729 error = EAGAIN;
730 else if (abstime == NULL)
731 error = cv_wait_sig(&ks->ks_cv, &sem_lock);
732 else {
733 for (;;) {
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747 }
748 ks->ks_waiters--;
749 if (error)
750 goto err;
751 }
752 ks->ks_value--;
753 error = 0;
754err:
755 mtx_unlock(&sem_lock);
756 fdrop(fp, td);
757 DP(("<<< kern_sem_wait leaving, error = %d\n", error));
758 return (error);
759}
760
761#ifndef _SYS_SYSPROTO_H_
762struct ksem_getvalue_args {
763 semid_t id;
764 int *val;
765};
766#endif
767int
768ksem_getvalue(struct thread *td, struct ksem_getvalue_args *uap)
769{
770 struct file *fp;
771 struct ksem *ks;
772 int error, val;
773
774 error = ksem_get(td, uap->id, &fp);
775 if (error)
776 return (error);
777 ks = fp->f_data;
778
779 mtx_lock(&sem_lock);
780#ifdef MAC
781 error = mac_posixsem_check_getvalue(td->td_ucred, fp->f_cred, ks);
782 if (error) {
783 mtx_unlock(&sem_lock);
784 fdrop(fp, td);
785 return (error);
786 }
787#endif
788 val = ks->ks_value;
789 vfs_timestamp(&ks->ks_atime);
790 mtx_unlock(&sem_lock);
791 fdrop(fp, td);
792 error = copyout(&val, uap->val, sizeof(val));
793 return (error);
794}
795
796#ifndef _SYS_SYSPROTO_H_
797struct ksem_destroy_args {
798 semid_t id;
799};
800#endif
801int
802ksem_destroy(struct thread *td, struct ksem_destroy_args *uap)
803{
804 struct file *fp;
805 struct ksem *ks;
806 int error;
807
808 error = ksem_get(td, uap->id, &fp);
809 if (error)
810 return (error);
811 ks = fp->f_data;
812 if (!(ks->ks_flags & KS_ANONYMOUS)) {
813 fdrop(fp, td);
814 return (EINVAL);
815 }
816 mtx_lock(&sem_lock);
817 if (ks->ks_waiters != 0) {
818 mtx_unlock(&sem_lock);
819 error = EBUSY;
820 goto err;
821 }
822 ks->ks_flags |= KS_DEAD;
823 mtx_unlock(&sem_lock);
824
825 error = kern_close(td, uap->id);
826err:
827 fdrop(fp, td);
828 return (error);
829}
830
831#define SYSCALL_DATA(syscallname) \
832static int syscallname##_syscall = SYS_##syscallname; \
833static int syscallname##_registered; \
834static struct sysent syscallname##_old_sysent; \
835MAKE_SYSENT(syscallname);
836
837#define SYSCALL_REGISTER(syscallname) do { \
838 error = syscall_register(& syscallname##_syscall, \
839 & syscallname##_sysent, & syscallname##_old_sysent); \
840 if (error) \
841 return (error); \
842 syscallname##_registered = 1; \
843} while(0)
844
845#define SYSCALL_DEREGISTER(syscallname) do { \
846 if (syscallname##_registered) { \
847 syscallname##_registered = 0; \
848 syscall_deregister(& syscallname##_syscall, \
849 & syscallname##_old_sysent); \
850 } \
851} while(0)
852
853SYSCALL_DATA(ksem_init);
854SYSCALL_DATA(ksem_open);
855SYSCALL_DATA(ksem_unlink);
856SYSCALL_DATA(ksem_close);
857SYSCALL_DATA(ksem_post);
858SYSCALL_DATA(ksem_wait);
859SYSCALL_DATA(ksem_timedwait);
860SYSCALL_DATA(ksem_trywait);
861SYSCALL_DATA(ksem_getvalue);
862SYSCALL_DATA(ksem_destroy);
863
864static int
865ksem_module_init(void)
866{
867 int error;
868
869 mtx_init(&sem_lock, "sem", NULL, MTX_DEF);
870 mtx_init(&ksem_count_lock, "ksem count", NULL, MTX_DEF);
871 sx_init(&ksem_dict_lock, "ksem dictionary");
872 ksem_dictionary = hashinit(1024, M_KSEM, &ksem_hash);
873 p31b_setcfg(CTL_P1003_1B_SEM_NSEMS_MAX, SEM_MAX);
874 p31b_setcfg(CTL_P1003_1B_SEM_VALUE_MAX, SEM_VALUE_MAX);
875
876 SYSCALL_REGISTER(ksem_init);
877 SYSCALL_REGISTER(ksem_open);
878 SYSCALL_REGISTER(ksem_unlink);
879 SYSCALL_REGISTER(ksem_close);
880 SYSCALL_REGISTER(ksem_post);
881 SYSCALL_REGISTER(ksem_wait);
882 SYSCALL_REGISTER(ksem_timedwait);
883 SYSCALL_REGISTER(ksem_trywait);
884 SYSCALL_REGISTER(ksem_getvalue);
885 SYSCALL_REGISTER(ksem_destroy);
886 return (0);
887}
888
889static void
890ksem_module_destroy(void)
891{
892
893 SYSCALL_DEREGISTER(ksem_init);
894 SYSCALL_DEREGISTER(ksem_open);
895 SYSCALL_DEREGISTER(ksem_unlink);
896 SYSCALL_DEREGISTER(ksem_close);
897 SYSCALL_DEREGISTER(ksem_post);
898 SYSCALL_DEREGISTER(ksem_wait);
899 SYSCALL_DEREGISTER(ksem_timedwait);
900 SYSCALL_DEREGISTER(ksem_trywait);
901 SYSCALL_DEREGISTER(ksem_getvalue);
902 SYSCALL_DEREGISTER(ksem_destroy);
903
904 hashdestroy(ksem_dictionary, M_KSEM, ksem_hash);
905 sx_destroy(&ksem_dict_lock);
906 mtx_destroy(&ksem_count_lock);
907 mtx_destroy(&sem_lock);
908}
909
910static int
911sem_modload(struct module *module, int cmd, void *arg)
912{
913 int error = 0;
914
915 switch (cmd) {
916 case MOD_LOAD:
917 error = ksem_module_init();
918 if (error)
919 ksem_module_destroy();
920 break;
921
922 case MOD_UNLOAD:
923 mtx_lock(&ksem_count_lock);
924 if (nsems != 0) {
925 error = EOPNOTSUPP;
926 mtx_unlock(&ksem_count_lock);
927 break;
928 }
929 ksem_dead = 1;
930 mtx_unlock(&ksem_count_lock);
931 ksem_module_destroy();
932 break;
933
934 case MOD_SHUTDOWN:
935 break;
936 default:
937 error = EINVAL;
938 break;
939 }
940 return (error);
941}
942
943static moduledata_t sem_mod = {
944 "sem",
945 &sem_modload,
946 NULL
947};
948
949DECLARE_MODULE(sem, sem_mod, SI_SUB_SYSV_SEM, SI_ORDER_FIRST);
950MODULE_VERSION(sem, 1);