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/10.0/sys/kern/uipc_sem.c 255219 2013-09-05 00:09:56Z pjd $");
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 *rightsp,
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_sendfile = invfo_sendfile,
153 .fo_flags = DFLAG_PASSABLE
154 };
155
156 FEATURE(posix_sem, "POSIX semaphores");
157
158 static int
159 ksem_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
160 int flags, struct thread *td)
161 {
162
163 return (EOPNOTSUPP);
164 }
165
166 static int
167 ksem_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
168 int flags, struct thread *td)
169 {
170
171 return (EOPNOTSUPP);
172 }
173
174 static int
175 ksem_truncate(struct file *fp, off_t length, struct ucred *active_cred,
176 struct thread *td)
177 {
178
179 return (EINVAL);
180 }
181
182 static int
183 ksem_ioctl(struct file *fp, u_long com, void *data,
184 struct ucred *active_cred, struct thread *td)
185 {
186
187 return (EOPNOTSUPP);
188 }
189
190 static int
191 ksem_poll(struct file *fp, int events, struct ucred *active_cred,
192 struct thread *td)
193 {
194
195 return (EOPNOTSUPP);
196 }
197
198 static int
199 ksem_kqfilter(struct file *fp, struct knote *kn)
200 {
201
202 return (EOPNOTSUPP);
203 }
204
205 static int
206 ksem_stat(struct file *fp, struct stat *sb, struct ucred *active_cred,
207 struct thread *td)
208 {
209 struct ksem *ks;
210 #ifdef MAC
211 int error;
212 #endif
213
214 ks = fp->f_data;
215
216 #ifdef MAC
217 error = mac_posixsem_check_stat(active_cred, fp->f_cred, ks);
218 if (error)
219 return (error);
220 #endif
221
222 /*
223 * Attempt to return sanish values for fstat() on a semaphore
224 * file descriptor.
225 */
226 bzero(sb, sizeof(*sb));
227
228 mtx_lock(&sem_lock);
229 sb->st_atim = ks->ks_atime;
230 sb->st_ctim = ks->ks_ctime;
231 sb->st_mtim = ks->ks_mtime;
232 sb->st_birthtim = ks->ks_birthtime;
233 sb->st_uid = ks->ks_uid;
234 sb->st_gid = ks->ks_gid;
235 sb->st_mode = S_IFREG | ks->ks_mode; /* XXX */
236 mtx_unlock(&sem_lock);
237
238 return (0);
239 }
240
241 static int
242 ksem_chmod(struct file *fp, mode_t mode, struct ucred *active_cred,
243 struct thread *td)
244 {
245 struct ksem *ks;
246 int error;
247
248 error = 0;
249 ks = fp->f_data;
250 mtx_lock(&sem_lock);
251 #ifdef MAC
252 error = mac_posixsem_check_setmode(active_cred, ks, mode);
253 if (error != 0)
254 goto out;
255 #endif
256 error = vaccess(VREG, ks->ks_mode, ks->ks_uid, ks->ks_gid, VADMIN,
257 active_cred, NULL);
258 if (error != 0)
259 goto out;
260 ks->ks_mode = mode & ACCESSPERMS;
261 out:
262 mtx_unlock(&sem_lock);
263 return (error);
264 }
265
266 static int
267 ksem_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
268 struct thread *td)
269 {
270 struct ksem *ks;
271 int error;
272
273 error = 0;
274 ks = fp->f_data;
275 mtx_lock(&sem_lock);
276 #ifdef MAC
277 error = mac_posixsem_check_setowner(active_cred, ks, uid, gid);
278 if (error != 0)
279 goto out;
280 #endif
281 if (uid == (uid_t)-1)
282 uid = ks->ks_uid;
283 if (gid == (gid_t)-1)
284 gid = ks->ks_gid;
285 if (((uid != ks->ks_uid && uid != active_cred->cr_uid) ||
286 (gid != ks->ks_gid && !groupmember(gid, active_cred))) &&
287 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN, 0)))
288 goto out;
289 ks->ks_uid = uid;
290 ks->ks_gid = gid;
291 out:
292 mtx_unlock(&sem_lock);
293 return (error);
294 }
295
296 static int
297 ksem_closef(struct file *fp, struct thread *td)
298 {
299 struct ksem *ks;
300
301 ks = fp->f_data;
302 fp->f_data = NULL;
303 ksem_drop(ks);
304
305 return (0);
306 }
307
308 /*
309 * ksem object management including creation and reference counting
310 * routines.
311 */
312 static struct ksem *
313 ksem_alloc(struct ucred *ucred, mode_t mode, unsigned int value)
314 {
315 struct ksem *ks;
316
317 mtx_lock(&ksem_count_lock);
318 if (nsems == p31b_getcfg(CTL_P1003_1B_SEM_NSEMS_MAX) || ksem_dead) {
319 mtx_unlock(&ksem_count_lock);
320 return (NULL);
321 }
322 nsems++;
323 mtx_unlock(&ksem_count_lock);
324 ks = malloc(sizeof(*ks), M_KSEM, M_WAITOK | M_ZERO);
325 ks->ks_uid = ucred->cr_uid;
326 ks->ks_gid = ucred->cr_gid;
327 ks->ks_mode = mode;
328 ks->ks_value = value;
329 cv_init(&ks->ks_cv, "ksem");
330 vfs_timestamp(&ks->ks_birthtime);
331 ks->ks_atime = ks->ks_mtime = ks->ks_ctime = ks->ks_birthtime;
332 refcount_init(&ks->ks_ref, 1);
333 #ifdef MAC
334 mac_posixsem_init(ks);
335 mac_posixsem_create(ucred, ks);
336 #endif
337
338 return (ks);
339 }
340
341 static struct ksem *
342 ksem_hold(struct ksem *ks)
343 {
344
345 refcount_acquire(&ks->ks_ref);
346 return (ks);
347 }
348
349 static void
350 ksem_drop(struct ksem *ks)
351 {
352
353 if (refcount_release(&ks->ks_ref)) {
354 #ifdef MAC
355 mac_posixsem_destroy(ks);
356 #endif
357 cv_destroy(&ks->ks_cv);
358 free(ks, M_KSEM);
359 mtx_lock(&ksem_count_lock);
360 nsems--;
361 mtx_unlock(&ksem_count_lock);
362 }
363 }
364
365 /*
366 * Determine if the credentials have sufficient permissions for read
367 * and write access.
368 */
369 static int
370 ksem_access(struct ksem *ks, struct ucred *ucred)
371 {
372 int error;
373
374 error = vaccess(VREG, ks->ks_mode, ks->ks_uid, ks->ks_gid,
375 VREAD | VWRITE, ucred, NULL);
376 if (error)
377 error = priv_check_cred(ucred, PRIV_SEM_WRITE, 0);
378 return (error);
379 }
380
381 /*
382 * Dictionary management. We maintain an in-kernel dictionary to map
383 * paths to semaphore objects. We use the FNV hash on the path to
384 * store the mappings in a hash table.
385 */
386 static struct ksem *
387 ksem_lookup(char *path, Fnv32_t fnv)
388 {
389 struct ksem_mapping *map;
390
391 LIST_FOREACH(map, KSEM_HASH(fnv), km_link) {
392 if (map->km_fnv != fnv)
393 continue;
394 if (strcmp(map->km_path, path) == 0)
395 return (map->km_ksem);
396 }
397
398 return (NULL);
399 }
400
401 static void
402 ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks)
403 {
404 struct ksem_mapping *map;
405
406 map = malloc(sizeof(struct ksem_mapping), M_KSEM, M_WAITOK);
407 map->km_path = path;
408 map->km_fnv = fnv;
409 map->km_ksem = ksem_hold(ks);
410 ks->ks_path = path;
411 LIST_INSERT_HEAD(KSEM_HASH(fnv), map, km_link);
412 }
413
414 static int
415 ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred)
416 {
417 struct ksem_mapping *map;
418 int error;
419
420 LIST_FOREACH(map, KSEM_HASH(fnv), km_link) {
421 if (map->km_fnv != fnv)
422 continue;
423 if (strcmp(map->km_path, path) == 0) {
424 #ifdef MAC
425 error = mac_posixsem_check_unlink(ucred, map->km_ksem);
426 if (error)
427 return (error);
428 #endif
429 error = ksem_access(map->km_ksem, ucred);
430 if (error)
431 return (error);
432 map->km_ksem->ks_path = NULL;
433 LIST_REMOVE(map, km_link);
434 ksem_drop(map->km_ksem);
435 free(map->km_path, M_KSEM);
436 free(map, M_KSEM);
437 return (0);
438 }
439 }
440
441 return (ENOENT);
442 }
443
444 static void
445 ksem_info_impl(struct ksem *ks, char *path, size_t size, uint32_t *value)
446 {
447
448 if (ks->ks_path == NULL)
449 return;
450 sx_slock(&ksem_dict_lock);
451 if (ks->ks_path != NULL)
452 strlcpy(path, ks->ks_path, size);
453 if (value != NULL)
454 *value = ks->ks_value;
455 sx_sunlock(&ksem_dict_lock);
456 }
457
458 static int
459 ksem_create_copyout_semid(struct thread *td, semid_t *semidp, int fd,
460 int compat32)
461 {
462 semid_t semid;
463 #ifdef COMPAT_FREEBSD32
464 int32_t semid32;
465 #endif
466 void *ptr;
467 size_t ptrs;
468
469 #ifdef COMPAT_FREEBSD32
470 if (compat32) {
471 semid32 = fd;
472 ptr = &semid32;
473 ptrs = sizeof(semid32);
474 } else {
475 #endif
476 semid = fd;
477 ptr = &semid;
478 ptrs = sizeof(semid);
479 compat32 = 0; /* silence gcc */
480 #ifdef COMPAT_FREEBSD32
481 }
482 #endif
483
484 return (copyout(ptr, semidp, ptrs));
485 }
486
487 /* Other helper routines. */
488 static int
489 ksem_create(struct thread *td, const char *name, semid_t *semidp, mode_t mode,
490 unsigned int value, int flags, int compat32)
491 {
492 struct filedesc *fdp;
493 struct ksem *ks;
494 struct file *fp;
495 char *path;
496 Fnv32_t fnv;
497 int error, fd;
498
499 if (value > SEM_VALUE_MAX)
500 return (EINVAL);
501
502 fdp = td->td_proc->p_fd;
503 mode = (mode & ~fdp->fd_cmask) & ACCESSPERMS;
504 error = falloc(td, &fp, &fd, O_CLOEXEC);
505 if (error) {
506 if (name == NULL)
507 error = ENOSPC;
508 return (error);
509 }
510
511 /*
512 * Go ahead and copyout the file descriptor now. This is a bit
513 * premature, but it is a lot easier to handle errors as opposed
514 * to later when we've possibly created a new semaphore, etc.
515 */
516 error = ksem_create_copyout_semid(td, semidp, fd, compat32);
517 if (error) {
518 fdclose(fdp, fp, fd, td);
519 fdrop(fp, td);
520 return (error);
521 }
522
523 if (name == NULL) {
524 /* Create an anonymous semaphore. */
525 ks = ksem_alloc(td->td_ucred, mode, value);
526 if (ks == NULL)
527 error = ENOSPC;
528 else
529 ks->ks_flags |= KS_ANONYMOUS;
530 } else {
531 path = malloc(MAXPATHLEN, M_KSEM, M_WAITOK);
532 error = copyinstr(name, path, MAXPATHLEN, NULL);
533
534 /* Require paths to start with a '/' character. */
535 if (error == 0 && path[0] != '/')
536 error = EINVAL;
537 if (error) {
538 fdclose(fdp, fp, fd, td);
539 fdrop(fp, td);
540 free(path, M_KSEM);
541 return (error);
542 }
543
544 fnv = fnv_32_str(path, FNV1_32_INIT);
545 sx_xlock(&ksem_dict_lock);
546 ks = ksem_lookup(path, fnv);
547 if (ks == NULL) {
548 /* Object does not exist, create it if requested. */
549 if (flags & O_CREAT) {
550 ks = ksem_alloc(td->td_ucred, mode, value);
551 if (ks == NULL)
552 error = ENFILE;
553 else {
554 ksem_insert(path, fnv, ks);
555 path = NULL;
556 }
557 } else
558 error = ENOENT;
559 } else {
560 /*
561 * Object already exists, obtain a new
562 * reference if requested and permitted.
563 */
564 if ((flags & (O_CREAT | O_EXCL)) ==
565 (O_CREAT | O_EXCL))
566 error = EEXIST;
567 else {
568 #ifdef MAC
569 error = mac_posixsem_check_open(td->td_ucred,
570 ks);
571 if (error == 0)
572 #endif
573 error = ksem_access(ks, td->td_ucred);
574 }
575 if (error == 0)
576 ksem_hold(ks);
577 #ifdef INVARIANTS
578 else
579 ks = NULL;
580 #endif
581 }
582 sx_xunlock(&ksem_dict_lock);
583 if (path)
584 free(path, M_KSEM);
585 }
586
587 if (error) {
588 KASSERT(ks == NULL, ("ksem_create error with a ksem"));
589 fdclose(fdp, fp, fd, td);
590 fdrop(fp, td);
591 return (error);
592 }
593 KASSERT(ks != NULL, ("ksem_create w/o a ksem"));
594
595 finit(fp, FREAD | FWRITE, DTYPE_SEM, ks, &ksem_ops);
596
597 fdrop(fp, td);
598
599 return (0);
600 }
601
602 static int
603 ksem_get(struct thread *td, semid_t id, cap_rights_t *rightsp,
604 struct file **fpp)
605 {
606 struct ksem *ks;
607 struct file *fp;
608 int error;
609
610 error = fget(td, id, rightsp, &fp);
611 if (error)
612 return (EINVAL);
613 if (fp->f_type != DTYPE_SEM) {
614 fdrop(fp, td);
615 return (EINVAL);
616 }
617 ks = fp->f_data;
618 if (ks->ks_flags & KS_DEAD) {
619 fdrop(fp, td);
620 return (EINVAL);
621 }
622 *fpp = fp;
623 return (0);
624 }
625
626 /* System calls. */
627 #ifndef _SYS_SYSPROTO_H_
628 struct ksem_init_args {
629 unsigned int value;
630 semid_t *idp;
631 };
632 #endif
633 int
634 sys_ksem_init(struct thread *td, struct ksem_init_args *uap)
635 {
636
637 return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value,
638 0, 0));
639 }
640
641 #ifndef _SYS_SYSPROTO_H_
642 struct ksem_open_args {
643 char *name;
644 int oflag;
645 mode_t mode;
646 unsigned int value;
647 semid_t *idp;
648 };
649 #endif
650 int
651 sys_ksem_open(struct thread *td, struct ksem_open_args *uap)
652 {
653
654 DP((">>> ksem_open start, pid=%d\n", (int)td->td_proc->p_pid));
655
656 if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0)
657 return (EINVAL);
658 return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value,
659 uap->oflag, 0));
660 }
661
662 #ifndef _SYS_SYSPROTO_H_
663 struct ksem_unlink_args {
664 char *name;
665 };
666 #endif
667 int
668 sys_ksem_unlink(struct thread *td, struct ksem_unlink_args *uap)
669 {
670 char *path;
671 Fnv32_t fnv;
672 int error;
673
674 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
675 error = copyinstr(uap->name, path, MAXPATHLEN, NULL);
676 if (error) {
677 free(path, M_TEMP);
678 return (error);
679 }
680
681 fnv = fnv_32_str(path, FNV1_32_INIT);
682 sx_xlock(&ksem_dict_lock);
683 error = ksem_remove(path, fnv, td->td_ucred);
684 sx_xunlock(&ksem_dict_lock);
685 free(path, M_TEMP);
686
687 return (error);
688 }
689
690 #ifndef _SYS_SYSPROTO_H_
691 struct ksem_close_args {
692 semid_t id;
693 };
694 #endif
695 int
696 sys_ksem_close(struct thread *td, struct ksem_close_args *uap)
697 {
698 struct ksem *ks;
699 struct file *fp;
700 int error;
701
702 /* No capability rights required to close a semaphore. */
703 error = ksem_get(td, uap->id, 0, &fp);
704 if (error)
705 return (error);
706 ks = fp->f_data;
707 if (ks->ks_flags & KS_ANONYMOUS) {
708 fdrop(fp, td);
709 return (EINVAL);
710 }
711 error = kern_close(td, uap->id);
712 fdrop(fp, td);
713 return (error);
714 }
715
716 #ifndef _SYS_SYSPROTO_H_
717 struct ksem_post_args {
718 semid_t id;
719 };
720 #endif
721 int
722 sys_ksem_post(struct thread *td, struct ksem_post_args *uap)
723 {
724 cap_rights_t rights;
725 struct file *fp;
726 struct ksem *ks;
727 int error;
728
729 error = ksem_get(td, uap->id,
730 cap_rights_init(&rights, CAP_SEM_POST), &fp);
731 if (error)
732 return (error);
733 ks = fp->f_data;
734
735 mtx_lock(&sem_lock);
736 #ifdef MAC
737 error = mac_posixsem_check_post(td->td_ucred, fp->f_cred, ks);
738 if (error)
739 goto err;
740 #endif
741 if (ks->ks_value == SEM_VALUE_MAX) {
742 error = EOVERFLOW;
743 goto err;
744 }
745 ++ks->ks_value;
746 if (ks->ks_waiters > 0)
747 cv_signal(&ks->ks_cv);
748 error = 0;
749 vfs_timestamp(&ks->ks_ctime);
750 err:
751 mtx_unlock(&sem_lock);
752 fdrop(fp, td);
753 return (error);
754 }
755
756 #ifndef _SYS_SYSPROTO_H_
757 struct ksem_wait_args {
758 semid_t id;
759 };
760 #endif
761 int
762 sys_ksem_wait(struct thread *td, struct ksem_wait_args *uap)
763 {
764
765 return (kern_sem_wait(td, uap->id, 0, NULL));
766 }
767
768 #ifndef _SYS_SYSPROTO_H_
769 struct ksem_timedwait_args {
770 semid_t id;
771 const struct timespec *abstime;
772 };
773 #endif
774 int
775 sys_ksem_timedwait(struct thread *td, struct ksem_timedwait_args *uap)
776 {
777 struct timespec abstime;
778 struct timespec *ts;
779 int error;
780
781 /*
782 * We allow a null timespec (wait forever).
783 */
784 if (uap->abstime == NULL)
785 ts = NULL;
786 else {
787 error = copyin(uap->abstime, &abstime, sizeof(abstime));
788 if (error != 0)
789 return (error);
790 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0)
791 return (EINVAL);
792 ts = &abstime;
793 }
794 return (kern_sem_wait(td, uap->id, 0, ts));
795 }
796
797 #ifndef _SYS_SYSPROTO_H_
798 struct ksem_trywait_args {
799 semid_t id;
800 };
801 #endif
802 int
803 sys_ksem_trywait(struct thread *td, struct ksem_trywait_args *uap)
804 {
805
806 return (kern_sem_wait(td, uap->id, 1, NULL));
807 }
808
809 static int
810 kern_sem_wait(struct thread *td, semid_t id, int tryflag,
811 struct timespec *abstime)
812 {
813 struct timespec ts1, ts2;
814 struct timeval tv;
815 cap_rights_t rights;
816 struct file *fp;
817 struct ksem *ks;
818 int error;
819
820 DP((">>> kern_sem_wait entered! pid=%d\n", (int)td->td_proc->p_pid));
821 error = ksem_get(td, id, cap_rights_init(&rights, CAP_SEM_WAIT), &fp);
822 if (error)
823 return (error);
824 ks = fp->f_data;
825 mtx_lock(&sem_lock);
826 DP((">>> kern_sem_wait critical section entered! pid=%d\n",
827 (int)td->td_proc->p_pid));
828 #ifdef MAC
829 error = mac_posixsem_check_wait(td->td_ucred, fp->f_cred, ks);
830 if (error) {
831 DP(("kern_sem_wait mac failed\n"));
832 goto err;
833 }
834 #endif
835 DP(("kern_sem_wait value = %d, tryflag %d\n", ks->ks_value, tryflag));
836 vfs_timestamp(&ks->ks_atime);
837 while (ks->ks_value == 0) {
838 ks->ks_waiters++;
839 if (tryflag != 0)
840 error = EAGAIN;
841 else if (abstime == NULL)
842 error = cv_wait_sig(&ks->ks_cv, &sem_lock);
843 else {
844 for (;;) {
845 ts1 = *abstime;
846 getnanotime(&ts2);
847 timespecsub(&ts1, &ts2);
848 TIMESPEC_TO_TIMEVAL(&tv, &ts1);
849 if (tv.tv_sec < 0) {
850 error = ETIMEDOUT;
851 break;
852 }
853 error = cv_timedwait_sig(&ks->ks_cv,
854 &sem_lock, tvtohz(&tv));
855 if (error != EWOULDBLOCK)
856 break;
857 }
858 }
859 ks->ks_waiters--;
860 if (error)
861 goto err;
862 }
863 ks->ks_value--;
864 DP(("kern_sem_wait value post-decrement = %d\n", ks->ks_value));
865 error = 0;
866 err:
867 mtx_unlock(&sem_lock);
868 fdrop(fp, td);
869 DP(("<<< kern_sem_wait leaving, pid=%d, error = %d\n",
870 (int)td->td_proc->p_pid, error));
871 return (error);
872 }
873
874 #ifndef _SYS_SYSPROTO_H_
875 struct ksem_getvalue_args {
876 semid_t id;
877 int *val;
878 };
879 #endif
880 int
881 sys_ksem_getvalue(struct thread *td, struct ksem_getvalue_args *uap)
882 {
883 cap_rights_t rights;
884 struct file *fp;
885 struct ksem *ks;
886 int error, val;
887
888 error = ksem_get(td, uap->id,
889 cap_rights_init(&rights, CAP_SEM_GETVALUE), &fp);
890 if (error)
891 return (error);
892 ks = fp->f_data;
893
894 mtx_lock(&sem_lock);
895 #ifdef MAC
896 error = mac_posixsem_check_getvalue(td->td_ucred, fp->f_cred, ks);
897 if (error) {
898 mtx_unlock(&sem_lock);
899 fdrop(fp, td);
900 return (error);
901 }
902 #endif
903 val = ks->ks_value;
904 vfs_timestamp(&ks->ks_atime);
905 mtx_unlock(&sem_lock);
906 fdrop(fp, td);
907 error = copyout(&val, uap->val, sizeof(val));
908 return (error);
909 }
910
911 #ifndef _SYS_SYSPROTO_H_
912 struct ksem_destroy_args {
913 semid_t id;
914 };
915 #endif
916 int
917 sys_ksem_destroy(struct thread *td, struct ksem_destroy_args *uap)
918 {
919 struct file *fp;
920 struct ksem *ks;
921 int error;
922
923 /* No capability rights required to close a semaphore. */
924 error = ksem_get(td, uap->id, 0, &fp);
925 if (error)
926 return (error);
927 ks = fp->f_data;
928 if (!(ks->ks_flags & KS_ANONYMOUS)) {
929 fdrop(fp, td);
930 return (EINVAL);
931 }
932 mtx_lock(&sem_lock);
933 if (ks->ks_waiters != 0) {
934 mtx_unlock(&sem_lock);
935 error = EBUSY;
936 goto err;
937 }
938 ks->ks_flags |= KS_DEAD;
939 mtx_unlock(&sem_lock);
940
941 error = kern_close(td, uap->id);
942 err:
943 fdrop(fp, td);
944 return (error);
945 }
946
947 static struct syscall_helper_data ksem_syscalls[] = {
948 SYSCALL_INIT_HELPER(ksem_init),
949 SYSCALL_INIT_HELPER(ksem_open),
950 SYSCALL_INIT_HELPER(ksem_unlink),
951 SYSCALL_INIT_HELPER(ksem_close),
952 SYSCALL_INIT_HELPER(ksem_post),
953 SYSCALL_INIT_HELPER(ksem_wait),
954 SYSCALL_INIT_HELPER(ksem_timedwait),
955 SYSCALL_INIT_HELPER(ksem_trywait),
956 SYSCALL_INIT_HELPER(ksem_getvalue),
957 SYSCALL_INIT_HELPER(ksem_destroy),
958 SYSCALL_INIT_LAST
959 };
960
961 #ifdef COMPAT_FREEBSD32
962 #include <compat/freebsd32/freebsd32.h>
963 #include <compat/freebsd32/freebsd32_proto.h>
964 #include <compat/freebsd32/freebsd32_signal.h>
965 #include <compat/freebsd32/freebsd32_syscall.h>
966 #include <compat/freebsd32/freebsd32_util.h>
967
968 int
969 freebsd32_ksem_init(struct thread *td, struct freebsd32_ksem_init_args *uap)
970 {
971
972 return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value,
973 0, 1));
974 }
975
976 int
977 freebsd32_ksem_open(struct thread *td, struct freebsd32_ksem_open_args *uap)
978 {
979
980 if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0)
981 return (EINVAL);
982 return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value,
983 uap->oflag, 1));
984 }
985
986 int
987 freebsd32_ksem_timedwait(struct thread *td,
988 struct freebsd32_ksem_timedwait_args *uap)
989 {
990 struct timespec32 abstime32;
991 struct timespec *ts, abstime;
992 int error;
993
994 /*
995 * We allow a null timespec (wait forever).
996 */
997 if (uap->abstime == NULL)
998 ts = NULL;
999 else {
1000 error = copyin(uap->abstime, &abstime32, sizeof(abstime32));
1001 if (error != 0)
1002 return (error);
1003 CP(abstime32, abstime, tv_sec);
1004 CP(abstime32, abstime, tv_nsec);
1005 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0)
1006 return (EINVAL);
1007 ts = &abstime;
1008 }
1009 return (kern_sem_wait(td, uap->id, 0, ts));
1010 }
1011
1012 static struct syscall_helper_data ksem32_syscalls[] = {
1013 SYSCALL32_INIT_HELPER(freebsd32_ksem_init),
1014 SYSCALL32_INIT_HELPER(freebsd32_ksem_open),
1015 SYSCALL32_INIT_HELPER_COMPAT(ksem_unlink),
1016 SYSCALL32_INIT_HELPER_COMPAT(ksem_close),
1017 SYSCALL32_INIT_HELPER_COMPAT(ksem_post),
1018 SYSCALL32_INIT_HELPER_COMPAT(ksem_wait),
1019 SYSCALL32_INIT_HELPER(freebsd32_ksem_timedwait),
1020 SYSCALL32_INIT_HELPER_COMPAT(ksem_trywait),
1021 SYSCALL32_INIT_HELPER_COMPAT(ksem_getvalue),
1022 SYSCALL32_INIT_HELPER_COMPAT(ksem_destroy),
1023 SYSCALL_INIT_LAST
1024 };
1025 #endif
1026
1027 static int
1028 ksem_module_init(void)
1029 {
1030 int error;
1031
1032 mtx_init(&sem_lock, "sem", NULL, MTX_DEF);
1033 mtx_init(&ksem_count_lock, "ksem count", NULL, MTX_DEF);
1034 sx_init(&ksem_dict_lock, "ksem dictionary");
1035 ksem_dictionary = hashinit(1024, M_KSEM, &ksem_hash);
1036 p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 200112L);
1037 p31b_setcfg(CTL_P1003_1B_SEM_NSEMS_MAX, SEM_MAX);
1038 p31b_setcfg(CTL_P1003_1B_SEM_VALUE_MAX, SEM_VALUE_MAX);
1039 ksem_info = ksem_info_impl;
1040
1041 error = syscall_helper_register(ksem_syscalls);
1042 if (error)
1043 return (error);
1044 #ifdef COMPAT_FREEBSD32
1045 error = syscall32_helper_register(ksem32_syscalls);
1046 if (error)
1047 return (error);
1048 #endif
1049 return (0);
1050 }
1051
1052 static void
1053 ksem_module_destroy(void)
1054 {
1055
1056 #ifdef COMPAT_FREEBSD32
1057 syscall32_helper_unregister(ksem32_syscalls);
1058 #endif
1059 syscall_helper_unregister(ksem_syscalls);
1060
1061 ksem_info = NULL;
1062 p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 0);
1063 hashdestroy(ksem_dictionary, M_KSEM, ksem_hash);
1064 sx_destroy(&ksem_dict_lock);
1065 mtx_destroy(&ksem_count_lock);
1066 mtx_destroy(&sem_lock);
1067 p31b_unsetcfg(CTL_P1003_1B_SEM_VALUE_MAX);
1068 p31b_unsetcfg(CTL_P1003_1B_SEM_NSEMS_MAX);
1069 }
1070
1071 static int
1072 sem_modload(struct module *module, int cmd, void *arg)
1073 {
1074 int error = 0;
1075
1076 switch (cmd) {
1077 case MOD_LOAD:
1078 error = ksem_module_init();
1079 if (error)
1080 ksem_module_destroy();
1081 break;
1082
1083 case MOD_UNLOAD:
1084 mtx_lock(&ksem_count_lock);
1085 if (nsems != 0) {
1086 error = EOPNOTSUPP;
1087 mtx_unlock(&ksem_count_lock);
1088 break;
1089 }
1090 ksem_dead = 1;
1091 mtx_unlock(&ksem_count_lock);
1092 ksem_module_destroy();
1093 break;
1094
1095 case MOD_SHUTDOWN:
1096 break;
1097 default:
1098 error = EINVAL;
1099 break;
1100 }
1101 return (error);
1102 }
1103
1104 static moduledata_t sem_mod = {
1105 "sem",
1106 &sem_modload,
1107 NULL
1108 };
1109
1110 DECLARE_MODULE(sem, sem_mod, SI_SUB_SYSV_SEM, SI_ORDER_FIRST);
1111 MODULE_VERSION(sem, 1);
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