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/9.1/sys/kern/uipc_sem.c 225617 2011-09-16 13:58:51Z kmacy $");
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 * - Update fstat(1)
75 * - Replace global sem_lock with mtx_pool locks?
76 * - Add a MAC check_create() hook for creating new named semaphores.
77 */
78
79 #ifndef SEM_MAX
80 #define SEM_MAX 30
81 #endif
82
83 #ifdef SEM_DEBUG
84 #define DP(x) printf x
85 #else
86 #define DP(x)
87 #endif
88
89 struct ksem_mapping {
90 char *km_path;
91 Fnv32_t km_fnv;
92 struct ksem *km_ksem;
93 LIST_ENTRY(ksem_mapping) km_link;
94 };
95
96 static MALLOC_DEFINE(M_KSEM, "ksem", "semaphore file descriptor");
97 static LIST_HEAD(, ksem_mapping) *ksem_dictionary;
98 static struct sx ksem_dict_lock;
99 static struct mtx ksem_count_lock;
100 static struct mtx sem_lock;
101 static u_long ksem_hash;
102 static int ksem_dead;
103
104 #define KSEM_HASH(fnv) (&ksem_dictionary[(fnv) & ksem_hash])
105
106 static int nsems = 0;
107 SYSCTL_DECL(_p1003_1b);
108 SYSCTL_INT(_p1003_1b, OID_AUTO, nsems, CTLFLAG_RD, &nsems, 0,
109 "Number of active kernel POSIX semaphores");
110
111 static int kern_sem_wait(struct thread *td, semid_t id, int tryflag,
112 struct timespec *abstime);
113 static int ksem_access(struct ksem *ks, struct ucred *ucred);
114 static struct ksem *ksem_alloc(struct ucred *ucred, mode_t mode,
115 unsigned int value);
116 static int ksem_create(struct thread *td, const char *path,
117 semid_t *semidp, mode_t mode, unsigned int value,
118 int flags, int compat32);
119 static void ksem_drop(struct ksem *ks);
120 static int ksem_get(struct thread *td, semid_t id, cap_rights_t rights,
121 struct file **fpp);
122 static struct ksem *ksem_hold(struct ksem *ks);
123 static void ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks);
124 static struct ksem *ksem_lookup(char *path, Fnv32_t fnv);
125 static void ksem_module_destroy(void);
126 static int ksem_module_init(void);
127 static int ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred);
128 static int sem_modload(struct module *module, int cmd, void *arg);
129
130 static fo_rdwr_t ksem_read;
131 static fo_rdwr_t ksem_write;
132 static fo_truncate_t ksem_truncate;
133 static fo_ioctl_t ksem_ioctl;
134 static fo_poll_t ksem_poll;
135 static fo_kqfilter_t ksem_kqfilter;
136 static fo_stat_t ksem_stat;
137 static fo_close_t ksem_closef;
138 static fo_chmod_t ksem_chmod;
139 static fo_chown_t ksem_chown;
140
141 /* File descriptor operations. */
142 static struct fileops ksem_ops = {
143 .fo_read = ksem_read,
144 .fo_write = ksem_write,
145 .fo_truncate = ksem_truncate,
146 .fo_ioctl = ksem_ioctl,
147 .fo_poll = ksem_poll,
148 .fo_kqfilter = ksem_kqfilter,
149 .fo_stat = ksem_stat,
150 .fo_close = ksem_closef,
151 .fo_chmod = ksem_chmod,
152 .fo_chown = ksem_chown,
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 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 LIST_REMOVE(map, km_link);
432 ksem_drop(map->km_ksem);
433 free(map->km_path, M_KSEM);
434 free(map, M_KSEM);
435 return (0);
436 }
437 }
438
439 return (ENOENT);
440 }
441
442 static int
443 ksem_create_copyout_semid(struct thread *td, semid_t *semidp, int fd,
444 int compat32)
445 {
446 semid_t semid;
447 #ifdef COMPAT_FREEBSD32
448 int32_t semid32;
449 #endif
450 void *ptr;
451 size_t ptrs;
452
453 #ifdef COMPAT_FREEBSD32
454 if (compat32) {
455 semid32 = fd;
456 ptr = &semid32;
457 ptrs = sizeof(semid32);
458 } else {
459 #endif
460 semid = fd;
461 ptr = &semid;
462 ptrs = sizeof(semid);
463 compat32 = 0; /* silence gcc */
464 #ifdef COMPAT_FREEBSD32
465 }
466 #endif
467
468 return (copyout(ptr, semidp, ptrs));
469 }
470
471 /* Other helper routines. */
472 static int
473 ksem_create(struct thread *td, const char *name, semid_t *semidp, mode_t mode,
474 unsigned int value, int flags, int compat32)
475 {
476 struct filedesc *fdp;
477 struct ksem *ks;
478 struct file *fp;
479 char *path;
480 Fnv32_t fnv;
481 int error, fd;
482
483 if (value > SEM_VALUE_MAX)
484 return (EINVAL);
485
486 fdp = td->td_proc->p_fd;
487 mode = (mode & ~fdp->fd_cmask) & ACCESSPERMS;
488 error = falloc(td, &fp, &fd, 0);
489 if (error) {
490 if (name == NULL)
491 error = ENOSPC;
492 return (error);
493 }
494
495 /*
496 * Go ahead and copyout the file descriptor now. This is a bit
497 * premature, but it is a lot easier to handle errors as opposed
498 * to later when we've possibly created a new semaphore, etc.
499 */
500 error = ksem_create_copyout_semid(td, semidp, fd, compat32);
501 if (error) {
502 fdclose(fdp, fp, fd, td);
503 fdrop(fp, td);
504 return (error);
505 }
506
507 if (name == NULL) {
508 /* Create an anonymous semaphore. */
509 ks = ksem_alloc(td->td_ucred, mode, value);
510 if (ks == NULL)
511 error = ENOSPC;
512 else
513 ks->ks_flags |= KS_ANONYMOUS;
514 } else {
515 path = malloc(MAXPATHLEN, M_KSEM, M_WAITOK);
516 error = copyinstr(name, path, MAXPATHLEN, NULL);
517
518 /* Require paths to start with a '/' character. */
519 if (error == 0 && path[0] != '/')
520 error = EINVAL;
521 if (error) {
522 fdclose(fdp, fp, fd, td);
523 fdrop(fp, td);
524 free(path, M_KSEM);
525 return (error);
526 }
527
528 fnv = fnv_32_str(path, FNV1_32_INIT);
529 sx_xlock(&ksem_dict_lock);
530 ks = ksem_lookup(path, fnv);
531 if (ks == NULL) {
532 /* Object does not exist, create it if requested. */
533 if (flags & O_CREAT) {
534 ks = ksem_alloc(td->td_ucred, mode, value);
535 if (ks == NULL)
536 error = ENFILE;
537 else {
538 ksem_insert(path, fnv, ks);
539 path = NULL;
540 }
541 } else
542 error = ENOENT;
543 } else {
544 /*
545 * Object already exists, obtain a new
546 * reference if requested and permitted.
547 */
548 if ((flags & (O_CREAT | O_EXCL)) ==
549 (O_CREAT | O_EXCL))
550 error = EEXIST;
551 else {
552 #ifdef MAC
553 error = mac_posixsem_check_open(td->td_ucred,
554 ks);
555 if (error == 0)
556 #endif
557 error = ksem_access(ks, td->td_ucred);
558 }
559 if (error == 0)
560 ksem_hold(ks);
561 #ifdef INVARIANTS
562 else
563 ks = NULL;
564 #endif
565 }
566 sx_xunlock(&ksem_dict_lock);
567 if (path)
568 free(path, M_KSEM);
569 }
570
571 if (error) {
572 KASSERT(ks == NULL, ("ksem_create error with a ksem"));
573 fdclose(fdp, fp, fd, td);
574 fdrop(fp, td);
575 return (error);
576 }
577 KASSERT(ks != NULL, ("ksem_create w/o a ksem"));
578
579 finit(fp, FREAD | FWRITE, DTYPE_SEM, ks, &ksem_ops);
580
581 FILEDESC_XLOCK(fdp);
582 if (fdp->fd_ofiles[fd] == fp)
583 fdp->fd_ofileflags[fd] |= UF_EXCLOSE;
584 FILEDESC_XUNLOCK(fdp);
585 fdrop(fp, td);
586
587 return (0);
588 }
589
590 static int
591 ksem_get(struct thread *td, semid_t id, cap_rights_t rights, struct file **fpp)
592 {
593 struct ksem *ks;
594 struct file *fp;
595 int error;
596
597 error = fget(td, id, rights, &fp);
598 if (error)
599 return (EINVAL);
600 if (fp->f_type != DTYPE_SEM) {
601 fdrop(fp, td);
602 return (EINVAL);
603 }
604 ks = fp->f_data;
605 if (ks->ks_flags & KS_DEAD) {
606 fdrop(fp, td);
607 return (EINVAL);
608 }
609 *fpp = fp;
610 return (0);
611 }
612
613 /* System calls. */
614 #ifndef _SYS_SYSPROTO_H_
615 struct ksem_init_args {
616 unsigned int value;
617 semid_t *idp;
618 };
619 #endif
620 int
621 sys_ksem_init(struct thread *td, struct ksem_init_args *uap)
622 {
623
624 return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value,
625 0, 0));
626 }
627
628 #ifndef _SYS_SYSPROTO_H_
629 struct ksem_open_args {
630 char *name;
631 int oflag;
632 mode_t mode;
633 unsigned int value;
634 semid_t *idp;
635 };
636 #endif
637 int
638 sys_ksem_open(struct thread *td, struct ksem_open_args *uap)
639 {
640
641 DP((">>> ksem_open start, pid=%d\n", (int)td->td_proc->p_pid));
642
643 if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0)
644 return (EINVAL);
645 return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value,
646 uap->oflag, 0));
647 }
648
649 #ifndef _SYS_SYSPROTO_H_
650 struct ksem_unlink_args {
651 char *name;
652 };
653 #endif
654 int
655 sys_ksem_unlink(struct thread *td, struct ksem_unlink_args *uap)
656 {
657 char *path;
658 Fnv32_t fnv;
659 int error;
660
661 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
662 error = copyinstr(uap->name, path, MAXPATHLEN, NULL);
663 if (error) {
664 free(path, M_TEMP);
665 return (error);
666 }
667
668 fnv = fnv_32_str(path, FNV1_32_INIT);
669 sx_xlock(&ksem_dict_lock);
670 error = ksem_remove(path, fnv, td->td_ucred);
671 sx_xunlock(&ksem_dict_lock);
672 free(path, M_TEMP);
673
674 return (error);
675 }
676
677 #ifndef _SYS_SYSPROTO_H_
678 struct ksem_close_args {
679 semid_t id;
680 };
681 #endif
682 int
683 sys_ksem_close(struct thread *td, struct ksem_close_args *uap)
684 {
685 struct ksem *ks;
686 struct file *fp;
687 int error;
688
689 /* No capability rights required to close a semaphore. */
690 error = ksem_get(td, uap->id, 0, &fp);
691 if (error)
692 return (error);
693 ks = fp->f_data;
694 if (ks->ks_flags & KS_ANONYMOUS) {
695 fdrop(fp, td);
696 return (EINVAL);
697 }
698 error = kern_close(td, uap->id);
699 fdrop(fp, td);
700 return (error);
701 }
702
703 #ifndef _SYS_SYSPROTO_H_
704 struct ksem_post_args {
705 semid_t id;
706 };
707 #endif
708 int
709 sys_ksem_post(struct thread *td, struct ksem_post_args *uap)
710 {
711 struct file *fp;
712 struct ksem *ks;
713 int error;
714
715 error = ksem_get(td, uap->id, CAP_SEM_POST, &fp);
716 if (error)
717 return (error);
718 ks = fp->f_data;
719
720 mtx_lock(&sem_lock);
721 #ifdef MAC
722 error = mac_posixsem_check_post(td->td_ucred, fp->f_cred, ks);
723 if (error)
724 goto err;
725 #endif
726 if (ks->ks_value == SEM_VALUE_MAX) {
727 error = EOVERFLOW;
728 goto err;
729 }
730 ++ks->ks_value;
731 if (ks->ks_waiters > 0)
732 cv_signal(&ks->ks_cv);
733 error = 0;
734 vfs_timestamp(&ks->ks_ctime);
735 err:
736 mtx_unlock(&sem_lock);
737 fdrop(fp, td);
738 return (error);
739 }
740
741 #ifndef _SYS_SYSPROTO_H_
742 struct ksem_wait_args {
743 semid_t id;
744 };
745 #endif
746 int
747 sys_ksem_wait(struct thread *td, struct ksem_wait_args *uap)
748 {
749
750 return (kern_sem_wait(td, uap->id, 0, NULL));
751 }
752
753 #ifndef _SYS_SYSPROTO_H_
754 struct ksem_timedwait_args {
755 semid_t id;
756 const struct timespec *abstime;
757 };
758 #endif
759 int
760 sys_ksem_timedwait(struct thread *td, struct ksem_timedwait_args *uap)
761 {
762 struct timespec abstime;
763 struct timespec *ts;
764 int error;
765
766 /*
767 * We allow a null timespec (wait forever).
768 */
769 if (uap->abstime == NULL)
770 ts = NULL;
771 else {
772 error = copyin(uap->abstime, &abstime, sizeof(abstime));
773 if (error != 0)
774 return (error);
775 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0)
776 return (EINVAL);
777 ts = &abstime;
778 }
779 return (kern_sem_wait(td, uap->id, 0, ts));
780 }
781
782 #ifndef _SYS_SYSPROTO_H_
783 struct ksem_trywait_args {
784 semid_t id;
785 };
786 #endif
787 int
788 sys_ksem_trywait(struct thread *td, struct ksem_trywait_args *uap)
789 {
790
791 return (kern_sem_wait(td, uap->id, 1, NULL));
792 }
793
794 static int
795 kern_sem_wait(struct thread *td, semid_t id, int tryflag,
796 struct timespec *abstime)
797 {
798 struct timespec ts1, ts2;
799 struct timeval tv;
800 struct file *fp;
801 struct ksem *ks;
802 int error;
803
804 DP((">>> kern_sem_wait entered! pid=%d\n", (int)td->td_proc->p_pid));
805 error = ksem_get(td, id, CAP_SEM_WAIT, &fp);
806 if (error)
807 return (error);
808 ks = fp->f_data;
809 mtx_lock(&sem_lock);
810 DP((">>> kern_sem_wait critical section entered! pid=%d\n",
811 (int)td->td_proc->p_pid));
812 #ifdef MAC
813 error = mac_posixsem_check_wait(td->td_ucred, fp->f_cred, ks);
814 if (error) {
815 DP(("kern_sem_wait mac failed\n"));
816 goto err;
817 }
818 #endif
819 DP(("kern_sem_wait value = %d, tryflag %d\n", ks->ks_value, tryflag));
820 vfs_timestamp(&ks->ks_atime);
821 while (ks->ks_value == 0) {
822 ks->ks_waiters++;
823 if (tryflag != 0)
824 error = EAGAIN;
825 else if (abstime == NULL)
826 error = cv_wait_sig(&ks->ks_cv, &sem_lock);
827 else {
828 for (;;) {
829 ts1 = *abstime;
830 getnanotime(&ts2);
831 timespecsub(&ts1, &ts2);
832 TIMESPEC_TO_TIMEVAL(&tv, &ts1);
833 if (tv.tv_sec < 0) {
834 error = ETIMEDOUT;
835 break;
836 }
837 error = cv_timedwait_sig(&ks->ks_cv,
838 &sem_lock, tvtohz(&tv));
839 if (error != EWOULDBLOCK)
840 break;
841 }
842 }
843 ks->ks_waiters--;
844 if (error)
845 goto err;
846 }
847 ks->ks_value--;
848 DP(("kern_sem_wait value post-decrement = %d\n", ks->ks_value));
849 error = 0;
850 err:
851 mtx_unlock(&sem_lock);
852 fdrop(fp, td);
853 DP(("<<< kern_sem_wait leaving, pid=%d, error = %d\n",
854 (int)td->td_proc->p_pid, error));
855 return (error);
856 }
857
858 #ifndef _SYS_SYSPROTO_H_
859 struct ksem_getvalue_args {
860 semid_t id;
861 int *val;
862 };
863 #endif
864 int
865 sys_ksem_getvalue(struct thread *td, struct ksem_getvalue_args *uap)
866 {
867 struct file *fp;
868 struct ksem *ks;
869 int error, val;
870
871 error = ksem_get(td, uap->id, CAP_SEM_GETVALUE, &fp);
872 if (error)
873 return (error);
874 ks = fp->f_data;
875
876 mtx_lock(&sem_lock);
877 #ifdef MAC
878 error = mac_posixsem_check_getvalue(td->td_ucred, fp->f_cred, ks);
879 if (error) {
880 mtx_unlock(&sem_lock);
881 fdrop(fp, td);
882 return (error);
883 }
884 #endif
885 val = ks->ks_value;
886 vfs_timestamp(&ks->ks_atime);
887 mtx_unlock(&sem_lock);
888 fdrop(fp, td);
889 error = copyout(&val, uap->val, sizeof(val));
890 return (error);
891 }
892
893 #ifndef _SYS_SYSPROTO_H_
894 struct ksem_destroy_args {
895 semid_t id;
896 };
897 #endif
898 int
899 sys_ksem_destroy(struct thread *td, struct ksem_destroy_args *uap)
900 {
901 struct file *fp;
902 struct ksem *ks;
903 int error;
904
905 /* No capability rights required to close a semaphore. */
906 error = ksem_get(td, uap->id, 0, &fp);
907 if (error)
908 return (error);
909 ks = fp->f_data;
910 if (!(ks->ks_flags & KS_ANONYMOUS)) {
911 fdrop(fp, td);
912 return (EINVAL);
913 }
914 mtx_lock(&sem_lock);
915 if (ks->ks_waiters != 0) {
916 mtx_unlock(&sem_lock);
917 error = EBUSY;
918 goto err;
919 }
920 ks->ks_flags |= KS_DEAD;
921 mtx_unlock(&sem_lock);
922
923 error = kern_close(td, uap->id);
924 err:
925 fdrop(fp, td);
926 return (error);
927 }
928
929 static struct syscall_helper_data ksem_syscalls[] = {
930 SYSCALL_INIT_HELPER(ksem_init),
931 SYSCALL_INIT_HELPER(ksem_open),
932 SYSCALL_INIT_HELPER(ksem_unlink),
933 SYSCALL_INIT_HELPER(ksem_close),
934 SYSCALL_INIT_HELPER(ksem_post),
935 SYSCALL_INIT_HELPER(ksem_wait),
936 SYSCALL_INIT_HELPER(ksem_timedwait),
937 SYSCALL_INIT_HELPER(ksem_trywait),
938 SYSCALL_INIT_HELPER(ksem_getvalue),
939 SYSCALL_INIT_HELPER(ksem_destroy),
940 SYSCALL_INIT_LAST
941 };
942
943 #ifdef COMPAT_FREEBSD32
944 #include <compat/freebsd32/freebsd32.h>
945 #include <compat/freebsd32/freebsd32_proto.h>
946 #include <compat/freebsd32/freebsd32_signal.h>
947 #include <compat/freebsd32/freebsd32_syscall.h>
948 #include <compat/freebsd32/freebsd32_util.h>
949
950 int
951 freebsd32_ksem_init(struct thread *td, struct freebsd32_ksem_init_args *uap)
952 {
953
954 return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value,
955 0, 1));
956 }
957
958 int
959 freebsd32_ksem_open(struct thread *td, struct freebsd32_ksem_open_args *uap)
960 {
961
962 if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0)
963 return (EINVAL);
964 return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value,
965 uap->oflag, 1));
966 }
967
968 int
969 freebsd32_ksem_timedwait(struct thread *td,
970 struct freebsd32_ksem_timedwait_args *uap)
971 {
972 struct timespec32 abstime32;
973 struct timespec *ts, abstime;
974 int error;
975
976 /*
977 * We allow a null timespec (wait forever).
978 */
979 if (uap->abstime == NULL)
980 ts = NULL;
981 else {
982 error = copyin(uap->abstime, &abstime32, sizeof(abstime32));
983 if (error != 0)
984 return (error);
985 CP(abstime32, abstime, tv_sec);
986 CP(abstime32, abstime, tv_nsec);
987 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0)
988 return (EINVAL);
989 ts = &abstime;
990 }
991 return (kern_sem_wait(td, uap->id, 0, ts));
992 }
993
994 static struct syscall_helper_data ksem32_syscalls[] = {
995 SYSCALL32_INIT_HELPER(freebsd32_ksem_init),
996 SYSCALL32_INIT_HELPER(freebsd32_ksem_open),
997 SYSCALL32_INIT_HELPER_COMPAT(ksem_unlink),
998 SYSCALL32_INIT_HELPER_COMPAT(ksem_close),
999 SYSCALL32_INIT_HELPER_COMPAT(ksem_post),
1000 SYSCALL32_INIT_HELPER_COMPAT(ksem_wait),
1001 SYSCALL32_INIT_HELPER(freebsd32_ksem_timedwait),
1002 SYSCALL32_INIT_HELPER_COMPAT(ksem_trywait),
1003 SYSCALL32_INIT_HELPER_COMPAT(ksem_getvalue),
1004 SYSCALL32_INIT_HELPER_COMPAT(ksem_destroy),
1005 SYSCALL_INIT_LAST
1006 };
1007 #endif
1008
1009 static int
1010 ksem_module_init(void)
1011 {
1012 int error;
1013
1014 mtx_init(&sem_lock, "sem", NULL, MTX_DEF);
1015 mtx_init(&ksem_count_lock, "ksem count", NULL, MTX_DEF);
1016 sx_init(&ksem_dict_lock, "ksem dictionary");
1017 ksem_dictionary = hashinit(1024, M_KSEM, &ksem_hash);
1018 p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 200112L);
1019 p31b_setcfg(CTL_P1003_1B_SEM_NSEMS_MAX, SEM_MAX);
1020 p31b_setcfg(CTL_P1003_1B_SEM_VALUE_MAX, SEM_VALUE_MAX);
1021
1022 error = syscall_helper_register(ksem_syscalls);
1023 if (error)
1024 return (error);
1025 #ifdef COMPAT_FREEBSD32
1026 error = syscall32_helper_register(ksem32_syscalls);
1027 if (error)
1028 return (error);
1029 #endif
1030 return (0);
1031 }
1032
1033 static void
1034 ksem_module_destroy(void)
1035 {
1036
1037 #ifdef COMPAT_FREEBSD32
1038 syscall32_helper_unregister(ksem32_syscalls);
1039 #endif
1040 syscall_helper_unregister(ksem_syscalls);
1041
1042 p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 0);
1043 hashdestroy(ksem_dictionary, M_KSEM, ksem_hash);
1044 sx_destroy(&ksem_dict_lock);
1045 mtx_destroy(&ksem_count_lock);
1046 mtx_destroy(&sem_lock);
1047 p31b_unsetcfg(CTL_P1003_1B_SEM_VALUE_MAX);
1048 p31b_unsetcfg(CTL_P1003_1B_SEM_NSEMS_MAX);
1049 }
1050
1051 static int
1052 sem_modload(struct module *module, int cmd, void *arg)
1053 {
1054 int error = 0;
1055
1056 switch (cmd) {
1057 case MOD_LOAD:
1058 error = ksem_module_init();
1059 if (error)
1060 ksem_module_destroy();
1061 break;
1062
1063 case MOD_UNLOAD:
1064 mtx_lock(&ksem_count_lock);
1065 if (nsems != 0) {
1066 error = EOPNOTSUPP;
1067 mtx_unlock(&ksem_count_lock);
1068 break;
1069 }
1070 ksem_dead = 1;
1071 mtx_unlock(&ksem_count_lock);
1072 ksem_module_destroy();
1073 break;
1074
1075 case MOD_SHUTDOWN:
1076 break;
1077 default:
1078 error = EINVAL;
1079 break;
1080 }
1081 return (error);
1082 }
1083
1084 static moduledata_t sem_mod = {
1085 "sem",
1086 &sem_modload,
1087 NULL
1088 };
1089
1090 DECLARE_MODULE(sem, sem_mod, SI_SUB_SYSV_SEM, SI_ORDER_FIRST);
1091 MODULE_VERSION(sem, 1);
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