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("$FreeBSD$");
36
37 #include "opt_compat.h"
38 #include "opt_posix.h"
39
40 #include <sys/param.h>
41 #include <sys/capability.h>
42 #include <sys/condvar.h>
43 #include <sys/fcntl.h>
44 #include <sys/file.h>
45 #include <sys/filedesc.h>
46 #include <sys/fnv_hash.h>
47 #include <sys/kernel.h>
48 #include <sys/ksem.h>
49 #include <sys/lock.h>
50 #include <sys/malloc.h>
51 #include <sys/module.h>
52 #include <sys/mutex.h>
53 #include <sys/priv.h>
54 #include <sys/proc.h>
55 #include <sys/posix4.h>
56 #include <sys/_semaphore.h>
57 #include <sys/stat.h>
58 #include <sys/syscall.h>
59 #include <sys/syscallsubr.h>
60 #include <sys/sysctl.h>
61 #include <sys/sysent.h>
62 #include <sys/sysproto.h>
63 #include <sys/systm.h>
64 #include <sys/sx.h>
65 #include <sys/vnode.h>
66
67 #include <security/mac/mac_framework.h>
68
69 FEATURE(p1003_1b_semaphores, "POSIX P1003.1B semaphores support");
70 /*
71 * TODO
72 *
73 * - Resource limits?
74 * - 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, cap_rights_t rights,
120 struct file **fpp);
121 static struct ksem *ksem_hold(struct ksem *ks);
122 static void ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks);
123 static struct ksem *ksem_lookup(char *path, Fnv32_t fnv);
124 static void ksem_module_destroy(void);
125 static int ksem_module_init(void);
126 static int ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred);
127 static int sem_modload(struct module *module, int cmd, void *arg);
128
129 static fo_rdwr_t ksem_read;
130 static fo_rdwr_t ksem_write;
131 static fo_truncate_t ksem_truncate;
132 static fo_ioctl_t ksem_ioctl;
133 static fo_poll_t ksem_poll;
134 static fo_kqfilter_t ksem_kqfilter;
135 static fo_stat_t ksem_stat;
136 static fo_close_t ksem_closef;
137 static fo_chmod_t ksem_chmod;
138 static fo_chown_t ksem_chown;
139
140 /* File descriptor operations. */
141 static struct fileops ksem_ops = {
142 .fo_read = ksem_read,
143 .fo_write = ksem_write,
144 .fo_truncate = ksem_truncate,
145 .fo_ioctl = ksem_ioctl,
146 .fo_poll = ksem_poll,
147 .fo_kqfilter = ksem_kqfilter,
148 .fo_stat = ksem_stat,
149 .fo_close = ksem_closef,
150 .fo_chmod = ksem_chmod,
151 .fo_chown = ksem_chown,
152 .fo_flags = DFLAG_PASSABLE
153 };
154
155 FEATURE(posix_sem, "POSIX semaphores");
156
157 static int
158 ksem_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
159 int flags, struct thread *td)
160 {
161
162 return (EOPNOTSUPP);
163 }
164
165 static int
166 ksem_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
167 int flags, struct thread *td)
168 {
169
170 return (EOPNOTSUPP);
171 }
172
173 static int
174 ksem_truncate(struct file *fp, off_t length, struct ucred *active_cred,
175 struct thread *td)
176 {
177
178 return (EINVAL);
179 }
180
181 static int
182 ksem_ioctl(struct file *fp, u_long com, void *data,
183 struct ucred *active_cred, struct thread *td)
184 {
185
186 return (EOPNOTSUPP);
187 }
188
189 static int
190 ksem_poll(struct file *fp, int events, struct ucred *active_cred,
191 struct thread *td)
192 {
193
194 return (EOPNOTSUPP);
195 }
196
197 static int
198 ksem_kqfilter(struct file *fp, struct knote *kn)
199 {
200
201 return (EOPNOTSUPP);
202 }
203
204 static int
205 ksem_stat(struct file *fp, struct stat *sb, struct ucred *active_cred,
206 struct thread *td)
207 {
208 struct ksem *ks;
209 #ifdef MAC
210 int error;
211 #endif
212
213 ks = fp->f_data;
214
215 #ifdef MAC
216 error = mac_posixsem_check_stat(active_cred, fp->f_cred, ks);
217 if (error)
218 return (error);
219 #endif
220
221 /*
222 * Attempt to return sanish values for fstat() on a semaphore
223 * file descriptor.
224 */
225 bzero(sb, sizeof(*sb));
226
227 mtx_lock(&sem_lock);
228 sb->st_atim = ks->ks_atime;
229 sb->st_ctim = ks->ks_ctime;
230 sb->st_mtim = ks->ks_mtime;
231 sb->st_birthtim = ks->ks_birthtime;
232 sb->st_uid = ks->ks_uid;
233 sb->st_gid = ks->ks_gid;
234 sb->st_mode = S_IFREG | ks->ks_mode; /* XXX */
235 mtx_unlock(&sem_lock);
236
237 return (0);
238 }
239
240 static int
241 ksem_chmod(struct file *fp, mode_t mode, struct ucred *active_cred,
242 struct thread *td)
243 {
244 struct ksem *ks;
245 int error;
246
247 error = 0;
248 ks = fp->f_data;
249 mtx_lock(&sem_lock);
250 #ifdef MAC
251 error = mac_posixsem_check_setmode(active_cred, ks, mode);
252 if (error != 0)
253 goto out;
254 #endif
255 error = vaccess(VREG, ks->ks_mode, ks->ks_uid, ks->ks_gid, VADMIN,
256 active_cred, NULL);
257 if (error != 0)
258 goto out;
259 ks->ks_mode = mode & ACCESSPERMS;
260 out:
261 mtx_unlock(&sem_lock);
262 return (error);
263 }
264
265 static int
266 ksem_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
267 struct thread *td)
268 {
269 struct ksem *ks;
270 int error;
271
272 error = 0;
273 ks = fp->f_data;
274 mtx_lock(&sem_lock);
275 #ifdef MAC
276 error = mac_posixsem_check_setowner(active_cred, ks, uid, gid);
277 if (error != 0)
278 goto out;
279 #endif
280 if (uid == (uid_t)-1)
281 uid = ks->ks_uid;
282 if (gid == (gid_t)-1)
283 gid = ks->ks_gid;
284 if (((uid != ks->ks_uid && uid != active_cred->cr_uid) ||
285 (gid != ks->ks_gid && !groupmember(gid, active_cred))) &&
286 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN, 0)))
287 goto out;
288 ks->ks_uid = uid;
289 ks->ks_gid = gid;
290 out:
291 mtx_unlock(&sem_lock);
292 return (error);
293 }
294
295 static int
296 ksem_closef(struct file *fp, struct thread *td)
297 {
298 struct ksem *ks;
299
300 ks = fp->f_data;
301 fp->f_data = NULL;
302 ksem_drop(ks);
303
304 return (0);
305 }
306
307 /*
308 * ksem object management including creation and reference counting
309 * routines.
310 */
311 static struct ksem *
312 ksem_alloc(struct ucred *ucred, mode_t mode, unsigned int value)
313 {
314 struct ksem *ks;
315
316 mtx_lock(&ksem_count_lock);
317 if (nsems == p31b_getcfg(CTL_P1003_1B_SEM_NSEMS_MAX) || ksem_dead) {
318 mtx_unlock(&ksem_count_lock);
319 return (NULL);
320 }
321 nsems++;
322 mtx_unlock(&ksem_count_lock);
323 ks = malloc(sizeof(*ks), M_KSEM, M_WAITOK | M_ZERO);
324 ks->ks_uid = ucred->cr_uid;
325 ks->ks_gid = ucred->cr_gid;
326 ks->ks_mode = mode;
327 ks->ks_value = value;
328 cv_init(&ks->ks_cv, "ksem");
329 vfs_timestamp(&ks->ks_birthtime);
330 ks->ks_atime = ks->ks_mtime = ks->ks_ctime = ks->ks_birthtime;
331 refcount_init(&ks->ks_ref, 1);
332 #ifdef MAC
333 mac_posixsem_init(ks);
334 mac_posixsem_create(ucred, ks);
335 #endif
336
337 return (ks);
338 }
339
340 static struct ksem *
341 ksem_hold(struct ksem *ks)
342 {
343
344 refcount_acquire(&ks->ks_ref);
345 return (ks);
346 }
347
348 static void
349 ksem_drop(struct ksem *ks)
350 {
351
352 if (refcount_release(&ks->ks_ref)) {
353 #ifdef MAC
354 mac_posixsem_destroy(ks);
355 #endif
356 cv_destroy(&ks->ks_cv);
357 free(ks, M_KSEM);
358 mtx_lock(&ksem_count_lock);
359 nsems--;
360 mtx_unlock(&ksem_count_lock);
361 }
362 }
363
364 /*
365 * Determine if the credentials have sufficient permissions for read
366 * and write access.
367 */
368 static int
369 ksem_access(struct ksem *ks, struct ucred *ucred)
370 {
371 int error;
372
373 error = vaccess(VREG, ks->ks_mode, ks->ks_uid, ks->ks_gid,
374 VREAD | VWRITE, ucred, NULL);
375 if (error)
376 error = priv_check_cred(ucred, PRIV_SEM_WRITE, 0);
377 return (error);
378 }
379
380 /*
381 * Dictionary management. We maintain an in-kernel dictionary to map
382 * paths to semaphore objects. We use the FNV hash on the path to
383 * store the mappings in a hash table.
384 */
385 static struct ksem *
386 ksem_lookup(char *path, Fnv32_t fnv)
387 {
388 struct ksem_mapping *map;
389
390 LIST_FOREACH(map, KSEM_HASH(fnv), km_link) {
391 if (map->km_fnv != fnv)
392 continue;
393 if (strcmp(map->km_path, path) == 0)
394 return (map->km_ksem);
395 }
396
397 return (NULL);
398 }
399
400 static void
401 ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks)
402 {
403 struct ksem_mapping *map;
404
405 map = malloc(sizeof(struct ksem_mapping), M_KSEM, M_WAITOK);
406 map->km_path = path;
407 map->km_fnv = fnv;
408 map->km_ksem = ksem_hold(ks);
409 ks->ks_path = path;
410 LIST_INSERT_HEAD(KSEM_HASH(fnv), map, km_link);
411 }
412
413 static int
414 ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred)
415 {
416 struct ksem_mapping *map;
417 int error;
418
419 LIST_FOREACH(map, KSEM_HASH(fnv), km_link) {
420 if (map->km_fnv != fnv)
421 continue;
422 if (strcmp(map->km_path, path) == 0) {
423 #ifdef MAC
424 error = mac_posixsem_check_unlink(ucred, map->km_ksem);
425 if (error)
426 return (error);
427 #endif
428 error = ksem_access(map->km_ksem, ucred);
429 if (error)
430 return (error);
431 map->km_ksem->ks_path = NULL;
432 LIST_REMOVE(map, km_link);
433 ksem_drop(map->km_ksem);
434 free(map->km_path, M_KSEM);
435 free(map, M_KSEM);
436 return (0);
437 }
438 }
439
440 return (ENOENT);
441 }
442
443 static void
444 ksem_info_impl(struct ksem *ks, char *path, size_t size, uint32_t *value)
445 {
446
447 if (ks->ks_path == NULL)
448 return;
449 sx_slock(&ksem_dict_lock);
450 if (ks->ks_path != NULL)
451 strlcpy(path, ks->ks_path, size);
452 if (value != NULL)
453 *value = ks->ks_value;
454 sx_sunlock(&ksem_dict_lock);
455 }
456
457 static int
458 ksem_create_copyout_semid(struct thread *td, semid_t *semidp, int fd,
459 int compat32)
460 {
461 semid_t semid;
462 #ifdef COMPAT_FREEBSD32
463 int32_t semid32;
464 #endif
465 void *ptr;
466 size_t ptrs;
467
468 #ifdef COMPAT_FREEBSD32
469 if (compat32) {
470 semid32 = fd;
471 ptr = &semid32;
472 ptrs = sizeof(semid32);
473 } else {
474 #endif
475 semid = fd;
476 ptr = &semid;
477 ptrs = sizeof(semid);
478 compat32 = 0; /* silence gcc */
479 #ifdef COMPAT_FREEBSD32
480 }
481 #endif
482
483 return (copyout(ptr, semidp, ptrs));
484 }
485
486 /* Other helper routines. */
487 static int
488 ksem_create(struct thread *td, const char *name, semid_t *semidp, mode_t mode,
489 unsigned int value, int flags, int compat32)
490 {
491 struct filedesc *fdp;
492 struct ksem *ks;
493 struct file *fp;
494 char *path;
495 Fnv32_t fnv;
496 int error, fd;
497
498 if (value > SEM_VALUE_MAX)
499 return (EINVAL);
500
501 fdp = td->td_proc->p_fd;
502 mode = (mode & ~fdp->fd_cmask) & ACCESSPERMS;
503 error = falloc(td, &fp, &fd, O_CLOEXEC);
504 if (error) {
505 if (name == NULL)
506 error = ENOSPC;
507 return (error);
508 }
509
510 /*
511 * Go ahead and copyout the file descriptor now. This is a bit
512 * premature, but it is a lot easier to handle errors as opposed
513 * to later when we've possibly created a new semaphore, etc.
514 */
515 error = ksem_create_copyout_semid(td, semidp, fd, compat32);
516 if (error) {
517 fdclose(fdp, fp, fd, td);
518 fdrop(fp, td);
519 return (error);
520 }
521
522 if (name == NULL) {
523 /* Create an anonymous semaphore. */
524 ks = ksem_alloc(td->td_ucred, mode, value);
525 if (ks == NULL)
526 error = ENOSPC;
527 else
528 ks->ks_flags |= KS_ANONYMOUS;
529 } else {
530 path = malloc(MAXPATHLEN, M_KSEM, M_WAITOK);
531 error = copyinstr(name, path, MAXPATHLEN, NULL);
532
533 /* Require paths to start with a '/' character. */
534 if (error == 0 && path[0] != '/')
535 error = EINVAL;
536 if (error) {
537 fdclose(fdp, fp, fd, td);
538 fdrop(fp, td);
539 free(path, M_KSEM);
540 return (error);
541 }
542
543 fnv = fnv_32_str(path, FNV1_32_INIT);
544 sx_xlock(&ksem_dict_lock);
545 ks = ksem_lookup(path, fnv);
546 if (ks == NULL) {
547 /* Object does not exist, create it if requested. */
548 if (flags & O_CREAT) {
549 ks = ksem_alloc(td->td_ucred, mode, value);
550 if (ks == NULL)
551 error = ENFILE;
552 else {
553 ksem_insert(path, fnv, ks);
554 path = NULL;
555 }
556 } else
557 error = ENOENT;
558 } else {
559 /*
560 * Object already exists, obtain a new
561 * reference if requested and permitted.
562 */
563 if ((flags & (O_CREAT | O_EXCL)) ==
564 (O_CREAT | O_EXCL))
565 error = EEXIST;
566 else {
567 #ifdef MAC
568 error = mac_posixsem_check_open(td->td_ucred,
569 ks);
570 if (error == 0)
571 #endif
572 error = ksem_access(ks, td->td_ucred);
573 }
574 if (error == 0)
575 ksem_hold(ks);
576 #ifdef INVARIANTS
577 else
578 ks = NULL;
579 #endif
580 }
581 sx_xunlock(&ksem_dict_lock);
582 if (path)
583 free(path, M_KSEM);
584 }
585
586 if (error) {
587 KASSERT(ks == NULL, ("ksem_create error with a ksem"));
588 fdclose(fdp, fp, fd, td);
589 fdrop(fp, td);
590 return (error);
591 }
592 KASSERT(ks != NULL, ("ksem_create w/o a ksem"));
593
594 finit(fp, FREAD | FWRITE, DTYPE_SEM, ks, &ksem_ops);
595
596 fdrop(fp, td);
597
598 return (0);
599 }
600
601 static int
602 ksem_get(struct thread *td, semid_t id, cap_rights_t rights, struct file **fpp)
603 {
604 struct ksem *ks;
605 struct file *fp;
606 int error;
607
608 error = fget(td, id, rights, &fp);
609 if (error)
610 return (EINVAL);
611 if (fp->f_type != DTYPE_SEM) {
612 fdrop(fp, td);
613 return (EINVAL);
614 }
615 ks = fp->f_data;
616 if (ks->ks_flags & KS_DEAD) {
617 fdrop(fp, td);
618 return (EINVAL);
619 }
620 *fpp = fp;
621 return (0);
622 }
623
624 /* System calls. */
625 #ifndef _SYS_SYSPROTO_H_
626 struct ksem_init_args {
627 unsigned int value;
628 semid_t *idp;
629 };
630 #endif
631 int
632 sys_ksem_init(struct thread *td, struct ksem_init_args *uap)
633 {
634
635 return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value,
636 0, 0));
637 }
638
639 #ifndef _SYS_SYSPROTO_H_
640 struct ksem_open_args {
641 char *name;
642 int oflag;
643 mode_t mode;
644 unsigned int value;
645 semid_t *idp;
646 };
647 #endif
648 int
649 sys_ksem_open(struct thread *td, struct ksem_open_args *uap)
650 {
651
652 DP((">>> ksem_open start, pid=%d\n", (int)td->td_proc->p_pid));
653
654 if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0)
655 return (EINVAL);
656 return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value,
657 uap->oflag, 0));
658 }
659
660 #ifndef _SYS_SYSPROTO_H_
661 struct ksem_unlink_args {
662 char *name;
663 };
664 #endif
665 int
666 sys_ksem_unlink(struct thread *td, struct ksem_unlink_args *uap)
667 {
668 char *path;
669 Fnv32_t fnv;
670 int error;
671
672 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
673 error = copyinstr(uap->name, path, MAXPATHLEN, NULL);
674 if (error) {
675 free(path, M_TEMP);
676 return (error);
677 }
678
679 fnv = fnv_32_str(path, FNV1_32_INIT);
680 sx_xlock(&ksem_dict_lock);
681 error = ksem_remove(path, fnv, td->td_ucred);
682 sx_xunlock(&ksem_dict_lock);
683 free(path, M_TEMP);
684
685 return (error);
686 }
687
688 #ifndef _SYS_SYSPROTO_H_
689 struct ksem_close_args {
690 semid_t id;
691 };
692 #endif
693 int
694 sys_ksem_close(struct thread *td, struct ksem_close_args *uap)
695 {
696 struct ksem *ks;
697 struct file *fp;
698 int error;
699
700 /* No capability rights required to close a semaphore. */
701 error = ksem_get(td, uap->id, 0, &fp);
702 if (error)
703 return (error);
704 ks = fp->f_data;
705 if (ks->ks_flags & KS_ANONYMOUS) {
706 fdrop(fp, td);
707 return (EINVAL);
708 }
709 error = kern_close(td, uap->id);
710 fdrop(fp, td);
711 return (error);
712 }
713
714 #ifndef _SYS_SYSPROTO_H_
715 struct ksem_post_args {
716 semid_t id;
717 };
718 #endif
719 int
720 sys_ksem_post(struct thread *td, struct ksem_post_args *uap)
721 {
722 struct file *fp;
723 struct ksem *ks;
724 int error;
725
726 error = ksem_get(td, uap->id, CAP_SEM_POST, &fp);
727 if (error)
728 return (error);
729 ks = fp->f_data;
730
731 mtx_lock(&sem_lock);
732 #ifdef MAC
733 error = mac_posixsem_check_post(td->td_ucred, fp->f_cred, ks);
734 if (error)
735 goto err;
736 #endif
737 if (ks->ks_value == SEM_VALUE_MAX) {
738 error = EOVERFLOW;
739 goto err;
740 }
741 ++ks->ks_value;
742 if (ks->ks_waiters > 0)
743 cv_signal(&ks->ks_cv);
744 error = 0;
745 vfs_timestamp(&ks->ks_ctime);
746 err:
747 mtx_unlock(&sem_lock);
748 fdrop(fp, td);
749 return (error);
750 }
751
752 #ifndef _SYS_SYSPROTO_H_
753 struct ksem_wait_args {
754 semid_t id;
755 };
756 #endif
757 int
758 sys_ksem_wait(struct thread *td, struct ksem_wait_args *uap)
759 {
760
761 return (kern_sem_wait(td, uap->id, 0, NULL));
762 }
763
764 #ifndef _SYS_SYSPROTO_H_
765 struct ksem_timedwait_args {
766 semid_t id;
767 const struct timespec *abstime;
768 };
769 #endif
770 int
771 sys_ksem_timedwait(struct thread *td, struct ksem_timedwait_args *uap)
772 {
773 struct timespec abstime;
774 struct timespec *ts;
775 int error;
776
777 /*
778 * We allow a null timespec (wait forever).
779 */
780 if (uap->abstime == NULL)
781 ts = NULL;
782 else {
783 error = copyin(uap->abstime, &abstime, sizeof(abstime));
784 if (error != 0)
785 return (error);
786 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0)
787 return (EINVAL);
788 ts = &abstime;
789 }
790 return (kern_sem_wait(td, uap->id, 0, ts));
791 }
792
793 #ifndef _SYS_SYSPROTO_H_
794 struct ksem_trywait_args {
795 semid_t id;
796 };
797 #endif
798 int
799 sys_ksem_trywait(struct thread *td, struct ksem_trywait_args *uap)
800 {
801
802 return (kern_sem_wait(td, uap->id, 1, NULL));
803 }
804
805 static int
806 kern_sem_wait(struct thread *td, semid_t id, int tryflag,
807 struct timespec *abstime)
808 {
809 struct timespec ts1, ts2;
810 struct timeval tv;
811 struct file *fp;
812 struct ksem *ks;
813 int error;
814
815 DP((">>> kern_sem_wait entered! pid=%d\n", (int)td->td_proc->p_pid));
816 error = ksem_get(td, id, CAP_SEM_WAIT, &fp);
817 if (error)
818 return (error);
819 ks = fp->f_data;
820 mtx_lock(&sem_lock);
821 DP((">>> kern_sem_wait critical section entered! pid=%d\n",
822 (int)td->td_proc->p_pid));
823 #ifdef MAC
824 error = mac_posixsem_check_wait(td->td_ucred, fp->f_cred, ks);
825 if (error) {
826 DP(("kern_sem_wait mac failed\n"));
827 goto err;
828 }
829 #endif
830 DP(("kern_sem_wait value = %d, tryflag %d\n", ks->ks_value, tryflag));
831 vfs_timestamp(&ks->ks_atime);
832 while (ks->ks_value == 0) {
833 ks->ks_waiters++;
834 if (tryflag != 0)
835 error = EAGAIN;
836 else if (abstime == NULL)
837 error = cv_wait_sig(&ks->ks_cv, &sem_lock);
838 else {
839 for (;;) {
840 ts1 = *abstime;
841 getnanotime(&ts2);
842 timespecsub(&ts1, &ts2);
843 TIMESPEC_TO_TIMEVAL(&tv, &ts1);
844 if (tv.tv_sec < 0) {
845 error = ETIMEDOUT;
846 break;
847 }
848 error = cv_timedwait_sig(&ks->ks_cv,
849 &sem_lock, tvtohz(&tv));
850 if (error != EWOULDBLOCK)
851 break;
852 }
853 }
854 ks->ks_waiters--;
855 if (error)
856 goto err;
857 }
858 ks->ks_value--;
859 DP(("kern_sem_wait value post-decrement = %d\n", ks->ks_value));
860 error = 0;
861 err:
862 mtx_unlock(&sem_lock);
863 fdrop(fp, td);
864 DP(("<<< kern_sem_wait leaving, pid=%d, error = %d\n",
865 (int)td->td_proc->p_pid, error));
866 return (error);
867 }
868
869 #ifndef _SYS_SYSPROTO_H_
870 struct ksem_getvalue_args {
871 semid_t id;
872 int *val;
873 };
874 #endif
875 int
876 sys_ksem_getvalue(struct thread *td, struct ksem_getvalue_args *uap)
877 {
878 struct file *fp;
879 struct ksem *ks;
880 int error, val;
881
882 error = ksem_get(td, uap->id, CAP_SEM_GETVALUE, &fp);
883 if (error)
884 return (error);
885 ks = fp->f_data;
886
887 mtx_lock(&sem_lock);
888 #ifdef MAC
889 error = mac_posixsem_check_getvalue(td->td_ucred, fp->f_cred, ks);
890 if (error) {
891 mtx_unlock(&sem_lock);
892 fdrop(fp, td);
893 return (error);
894 }
895 #endif
896 val = ks->ks_value;
897 vfs_timestamp(&ks->ks_atime);
898 mtx_unlock(&sem_lock);
899 fdrop(fp, td);
900 error = copyout(&val, uap->val, sizeof(val));
901 return (error);
902 }
903
904 #ifndef _SYS_SYSPROTO_H_
905 struct ksem_destroy_args {
906 semid_t id;
907 };
908 #endif
909 int
910 sys_ksem_destroy(struct thread *td, struct ksem_destroy_args *uap)
911 {
912 struct file *fp;
913 struct ksem *ks;
914 int error;
915
916 /* No capability rights required to close a semaphore. */
917 error = ksem_get(td, uap->id, 0, &fp);
918 if (error)
919 return (error);
920 ks = fp->f_data;
921 if (!(ks->ks_flags & KS_ANONYMOUS)) {
922 fdrop(fp, td);
923 return (EINVAL);
924 }
925 mtx_lock(&sem_lock);
926 if (ks->ks_waiters != 0) {
927 mtx_unlock(&sem_lock);
928 error = EBUSY;
929 goto err;
930 }
931 ks->ks_flags |= KS_DEAD;
932 mtx_unlock(&sem_lock);
933
934 error = kern_close(td, uap->id);
935 err:
936 fdrop(fp, td);
937 return (error);
938 }
939
940 static struct syscall_helper_data ksem_syscalls[] = {
941 SYSCALL_INIT_HELPER(ksem_init),
942 SYSCALL_INIT_HELPER(ksem_open),
943 SYSCALL_INIT_HELPER(ksem_unlink),
944 SYSCALL_INIT_HELPER(ksem_close),
945 SYSCALL_INIT_HELPER(ksem_post),
946 SYSCALL_INIT_HELPER(ksem_wait),
947 SYSCALL_INIT_HELPER(ksem_timedwait),
948 SYSCALL_INIT_HELPER(ksem_trywait),
949 SYSCALL_INIT_HELPER(ksem_getvalue),
950 SYSCALL_INIT_HELPER(ksem_destroy),
951 SYSCALL_INIT_LAST
952 };
953
954 #ifdef COMPAT_FREEBSD32
955 #include <compat/freebsd32/freebsd32.h>
956 #include <compat/freebsd32/freebsd32_proto.h>
957 #include <compat/freebsd32/freebsd32_signal.h>
958 #include <compat/freebsd32/freebsd32_syscall.h>
959 #include <compat/freebsd32/freebsd32_util.h>
960
961 int
962 freebsd32_ksem_init(struct thread *td, struct freebsd32_ksem_init_args *uap)
963 {
964
965 return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value,
966 0, 1));
967 }
968
969 int
970 freebsd32_ksem_open(struct thread *td, struct freebsd32_ksem_open_args *uap)
971 {
972
973 if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0)
974 return (EINVAL);
975 return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value,
976 uap->oflag, 1));
977 }
978
979 int
980 freebsd32_ksem_timedwait(struct thread *td,
981 struct freebsd32_ksem_timedwait_args *uap)
982 {
983 struct timespec32 abstime32;
984 struct timespec *ts, abstime;
985 int error;
986
987 /*
988 * We allow a null timespec (wait forever).
989 */
990 if (uap->abstime == NULL)
991 ts = NULL;
992 else {
993 error = copyin(uap->abstime, &abstime32, sizeof(abstime32));
994 if (error != 0)
995 return (error);
996 CP(abstime32, abstime, tv_sec);
997 CP(abstime32, abstime, tv_nsec);
998 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0)
999 return (EINVAL);
1000 ts = &abstime;
1001 }
1002 return (kern_sem_wait(td, uap->id, 0, ts));
1003 }
1004
1005 static struct syscall_helper_data ksem32_syscalls[] = {
1006 SYSCALL32_INIT_HELPER(freebsd32_ksem_init),
1007 SYSCALL32_INIT_HELPER(freebsd32_ksem_open),
1008 SYSCALL32_INIT_HELPER_COMPAT(ksem_unlink),
1009 SYSCALL32_INIT_HELPER_COMPAT(ksem_close),
1010 SYSCALL32_INIT_HELPER_COMPAT(ksem_post),
1011 SYSCALL32_INIT_HELPER_COMPAT(ksem_wait),
1012 SYSCALL32_INIT_HELPER(freebsd32_ksem_timedwait),
1013 SYSCALL32_INIT_HELPER_COMPAT(ksem_trywait),
1014 SYSCALL32_INIT_HELPER_COMPAT(ksem_getvalue),
1015 SYSCALL32_INIT_HELPER_COMPAT(ksem_destroy),
1016 SYSCALL_INIT_LAST
1017 };
1018 #endif
1019
1020 static int
1021 ksem_module_init(void)
1022 {
1023 int error;
1024
1025 mtx_init(&sem_lock, "sem", NULL, MTX_DEF);
1026 mtx_init(&ksem_count_lock, "ksem count", NULL, MTX_DEF);
1027 sx_init(&ksem_dict_lock, "ksem dictionary");
1028 ksem_dictionary = hashinit(1024, M_KSEM, &ksem_hash);
1029 p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 200112L);
1030 p31b_setcfg(CTL_P1003_1B_SEM_NSEMS_MAX, SEM_MAX);
1031 p31b_setcfg(CTL_P1003_1B_SEM_VALUE_MAX, SEM_VALUE_MAX);
1032 ksem_info = ksem_info_impl;
1033
1034 error = syscall_helper_register(ksem_syscalls);
1035 if (error)
1036 return (error);
1037 #ifdef COMPAT_FREEBSD32
1038 error = syscall32_helper_register(ksem32_syscalls);
1039 if (error)
1040 return (error);
1041 #endif
1042 return (0);
1043 }
1044
1045 static void
1046 ksem_module_destroy(void)
1047 {
1048
1049 #ifdef COMPAT_FREEBSD32
1050 syscall32_helper_unregister(ksem32_syscalls);
1051 #endif
1052 syscall_helper_unregister(ksem_syscalls);
1053
1054 ksem_info = NULL;
1055 p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 0);
1056 hashdestroy(ksem_dictionary, M_KSEM, ksem_hash);
1057 sx_destroy(&ksem_dict_lock);
1058 mtx_destroy(&ksem_count_lock);
1059 mtx_destroy(&sem_lock);
1060 p31b_unsetcfg(CTL_P1003_1B_SEM_VALUE_MAX);
1061 p31b_unsetcfg(CTL_P1003_1B_SEM_NSEMS_MAX);
1062 }
1063
1064 static int
1065 sem_modload(struct module *module, int cmd, void *arg)
1066 {
1067 int error = 0;
1068
1069 switch (cmd) {
1070 case MOD_LOAD:
1071 error = ksem_module_init();
1072 if (error)
1073 ksem_module_destroy();
1074 break;
1075
1076 case MOD_UNLOAD:
1077 mtx_lock(&ksem_count_lock);
1078 if (nsems != 0) {
1079 error = EOPNOTSUPP;
1080 mtx_unlock(&ksem_count_lock);
1081 break;
1082 }
1083 ksem_dead = 1;
1084 mtx_unlock(&ksem_count_lock);
1085 ksem_module_destroy();
1086 break;
1087
1088 case MOD_SHUTDOWN:
1089 break;
1090 default:
1091 error = EINVAL;
1092 break;
1093 }
1094 return (error);
1095 }
1096
1097 static moduledata_t sem_mod = {
1098 "sem",
1099 &sem_modload,
1100 NULL
1101 };
1102
1103 DECLARE_MODULE(sem, sem_mod, SI_SUB_SYSV_SEM, SI_ORDER_FIRST);
1104 MODULE_VERSION(sem, 1);
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