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/10.3/sys/kern/uipc_sem.c 325873 2017-11-15 22:45:13Z gordon $");
36
37 #include "opt_compat.h"
38 #include "opt_posix.h"
39
40 #include <sys/param.h>
41 #include <sys/capsicum.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/jail.h>
48 #include <sys/kernel.h>
49 #include <sys/ksem.h>
50 #include <sys/lock.h>
51 #include <sys/malloc.h>
52 #include <sys/module.h>
53 #include <sys/mutex.h>
54 #include <sys/priv.h>
55 #include <sys/proc.h>
56 #include <sys/posix4.h>
57 #include <sys/_semaphore.h>
58 #include <sys/stat.h>
59 #include <sys/syscall.h>
60 #include <sys/syscallsubr.h>
61 #include <sys/sysctl.h>
62 #include <sys/sysent.h>
63 #include <sys/sysproto.h>
64 #include <sys/systm.h>
65 #include <sys/sx.h>
66 #include <sys/vnode.h>
67
68 #include <security/mac/mac_framework.h>
69
70 FEATURE(p1003_1b_semaphores, "POSIX P1003.1B semaphores support");
71 /*
72 * TODO
73 *
74 * - Resource limits?
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 *rightsp,
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_sendfile = invfo_sendfile,
154 .fo_flags = DFLAG_PASSABLE
155 };
156
157 FEATURE(posix_sem, "POSIX semaphores");
158
159 static int
160 ksem_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
161 int flags, struct thread *td)
162 {
163
164 return (EOPNOTSUPP);
165 }
166
167 static int
168 ksem_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
169 int flags, struct thread *td)
170 {
171
172 return (EOPNOTSUPP);
173 }
174
175 static int
176 ksem_truncate(struct file *fp, off_t length, struct ucred *active_cred,
177 struct thread *td)
178 {
179
180 return (EINVAL);
181 }
182
183 static int
184 ksem_ioctl(struct file *fp, u_long com, void *data,
185 struct ucred *active_cred, struct thread *td)
186 {
187
188 return (EOPNOTSUPP);
189 }
190
191 static int
192 ksem_poll(struct file *fp, int events, struct ucred *active_cred,
193 struct thread *td)
194 {
195
196 return (EOPNOTSUPP);
197 }
198
199 static int
200 ksem_kqfilter(struct file *fp, struct knote *kn)
201 {
202
203 return (EOPNOTSUPP);
204 }
205
206 static int
207 ksem_stat(struct file *fp, struct stat *sb, struct ucred *active_cred,
208 struct thread *td)
209 {
210 struct ksem *ks;
211 #ifdef MAC
212 int error;
213 #endif
214
215 ks = fp->f_data;
216
217 #ifdef MAC
218 error = mac_posixsem_check_stat(active_cred, fp->f_cred, ks);
219 if (error)
220 return (error);
221 #endif
222
223 /*
224 * Attempt to return sanish values for fstat() on a semaphore
225 * file descriptor.
226 */
227 bzero(sb, sizeof(*sb));
228
229 mtx_lock(&sem_lock);
230 sb->st_atim = ks->ks_atime;
231 sb->st_ctim = ks->ks_ctime;
232 sb->st_mtim = ks->ks_mtime;
233 sb->st_birthtim = ks->ks_birthtime;
234 sb->st_uid = ks->ks_uid;
235 sb->st_gid = ks->ks_gid;
236 sb->st_mode = S_IFREG | ks->ks_mode; /* XXX */
237 mtx_unlock(&sem_lock);
238
239 return (0);
240 }
241
242 static int
243 ksem_chmod(struct file *fp, mode_t mode, struct ucred *active_cred,
244 struct thread *td)
245 {
246 struct ksem *ks;
247 int error;
248
249 error = 0;
250 ks = fp->f_data;
251 mtx_lock(&sem_lock);
252 #ifdef MAC
253 error = mac_posixsem_check_setmode(active_cred, ks, mode);
254 if (error != 0)
255 goto out;
256 #endif
257 error = vaccess(VREG, ks->ks_mode, ks->ks_uid, ks->ks_gid, VADMIN,
258 active_cred, NULL);
259 if (error != 0)
260 goto out;
261 ks->ks_mode = mode & ACCESSPERMS;
262 out:
263 mtx_unlock(&sem_lock);
264 return (error);
265 }
266
267 static int
268 ksem_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
269 struct thread *td)
270 {
271 struct ksem *ks;
272 int error;
273
274 error = 0;
275 ks = fp->f_data;
276 mtx_lock(&sem_lock);
277 #ifdef MAC
278 error = mac_posixsem_check_setowner(active_cred, ks, uid, gid);
279 if (error != 0)
280 goto out;
281 #endif
282 if (uid == (uid_t)-1)
283 uid = ks->ks_uid;
284 if (gid == (gid_t)-1)
285 gid = ks->ks_gid;
286 if (((uid != ks->ks_uid && uid != active_cred->cr_uid) ||
287 (gid != ks->ks_gid && !groupmember(gid, active_cred))) &&
288 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN, 0)))
289 goto out;
290 ks->ks_uid = uid;
291 ks->ks_gid = gid;
292 out:
293 mtx_unlock(&sem_lock);
294 return (error);
295 }
296
297 static int
298 ksem_closef(struct file *fp, struct thread *td)
299 {
300 struct ksem *ks;
301
302 ks = fp->f_data;
303 fp->f_data = NULL;
304 ksem_drop(ks);
305
306 return (0);
307 }
308
309 /*
310 * ksem object management including creation and reference counting
311 * routines.
312 */
313 static struct ksem *
314 ksem_alloc(struct ucred *ucred, mode_t mode, unsigned int value)
315 {
316 struct ksem *ks;
317
318 mtx_lock(&ksem_count_lock);
319 if (nsems == p31b_getcfg(CTL_P1003_1B_SEM_NSEMS_MAX) || ksem_dead) {
320 mtx_unlock(&ksem_count_lock);
321 return (NULL);
322 }
323 nsems++;
324 mtx_unlock(&ksem_count_lock);
325 ks = malloc(sizeof(*ks), M_KSEM, M_WAITOK | M_ZERO);
326 ks->ks_uid = ucred->cr_uid;
327 ks->ks_gid = ucred->cr_gid;
328 ks->ks_mode = mode;
329 ks->ks_value = value;
330 cv_init(&ks->ks_cv, "ksem");
331 vfs_timestamp(&ks->ks_birthtime);
332 ks->ks_atime = ks->ks_mtime = ks->ks_ctime = ks->ks_birthtime;
333 refcount_init(&ks->ks_ref, 1);
334 #ifdef MAC
335 mac_posixsem_init(ks);
336 mac_posixsem_create(ucred, ks);
337 #endif
338
339 return (ks);
340 }
341
342 static struct ksem *
343 ksem_hold(struct ksem *ks)
344 {
345
346 refcount_acquire(&ks->ks_ref);
347 return (ks);
348 }
349
350 static void
351 ksem_drop(struct ksem *ks)
352 {
353
354 if (refcount_release(&ks->ks_ref)) {
355 #ifdef MAC
356 mac_posixsem_destroy(ks);
357 #endif
358 cv_destroy(&ks->ks_cv);
359 free(ks, M_KSEM);
360 mtx_lock(&ksem_count_lock);
361 nsems--;
362 mtx_unlock(&ksem_count_lock);
363 }
364 }
365
366 /*
367 * Determine if the credentials have sufficient permissions for read
368 * and write access.
369 */
370 static int
371 ksem_access(struct ksem *ks, struct ucred *ucred)
372 {
373 int error;
374
375 error = vaccess(VREG, ks->ks_mode, ks->ks_uid, ks->ks_gid,
376 VREAD | VWRITE, ucred, NULL);
377 if (error)
378 error = priv_check_cred(ucred, PRIV_SEM_WRITE, 0);
379 return (error);
380 }
381
382 /*
383 * Dictionary management. We maintain an in-kernel dictionary to map
384 * paths to semaphore objects. We use the FNV hash on the path to
385 * store the mappings in a hash table.
386 */
387 static struct ksem *
388 ksem_lookup(char *path, Fnv32_t fnv)
389 {
390 struct ksem_mapping *map;
391
392 LIST_FOREACH(map, KSEM_HASH(fnv), km_link) {
393 if (map->km_fnv != fnv)
394 continue;
395 if (strcmp(map->km_path, path) == 0)
396 return (map->km_ksem);
397 }
398
399 return (NULL);
400 }
401
402 static void
403 ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks)
404 {
405 struct ksem_mapping *map;
406
407 map = malloc(sizeof(struct ksem_mapping), M_KSEM, M_WAITOK);
408 map->km_path = path;
409 map->km_fnv = fnv;
410 map->km_ksem = ksem_hold(ks);
411 ks->ks_path = path;
412 LIST_INSERT_HEAD(KSEM_HASH(fnv), map, km_link);
413 }
414
415 static int
416 ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred)
417 {
418 struct ksem_mapping *map;
419 int error;
420
421 LIST_FOREACH(map, KSEM_HASH(fnv), km_link) {
422 if (map->km_fnv != fnv)
423 continue;
424 if (strcmp(map->km_path, path) == 0) {
425 #ifdef MAC
426 error = mac_posixsem_check_unlink(ucred, map->km_ksem);
427 if (error)
428 return (error);
429 #endif
430 error = ksem_access(map->km_ksem, ucred);
431 if (error)
432 return (error);
433 map->km_ksem->ks_path = NULL;
434 LIST_REMOVE(map, km_link);
435 ksem_drop(map->km_ksem);
436 free(map->km_path, M_KSEM);
437 free(map, M_KSEM);
438 return (0);
439 }
440 }
441
442 return (ENOENT);
443 }
444
445 static void
446 ksem_info_impl(struct ksem *ks, char *path, size_t size, uint32_t *value)
447 {
448 const char *ks_path, *pr_path;
449 size_t pr_pathlen;
450
451 if (ks->ks_path == NULL)
452 return;
453 sx_slock(&ksem_dict_lock);
454 ks_path = ks->ks_path;
455 if (ks_path != NULL) {
456 pr_path = curthread->td_ucred->cr_prison->pr_path;
457 if (strcmp(pr_path, "/") != 0) {
458 /* Return the jail-rooted pathname. */
459 pr_pathlen = strlen(pr_path);
460 if (strncmp(ks_path, pr_path, pr_pathlen) == 0 &&
461 ks_path[pr_pathlen] == '/')
462 ks_path += pr_pathlen;
463 }
464 strlcpy(path, ks_path, size);
465 }
466 if (value != NULL)
467 *value = ks->ks_value;
468 sx_sunlock(&ksem_dict_lock);
469 }
470
471 static int
472 ksem_create_copyout_semid(struct thread *td, semid_t *semidp, int fd,
473 int compat32)
474 {
475 semid_t semid;
476 #ifdef COMPAT_FREEBSD32
477 int32_t semid32;
478 #endif
479 void *ptr;
480 size_t ptrs;
481
482 #ifdef COMPAT_FREEBSD32
483 if (compat32) {
484 semid32 = fd;
485 ptr = &semid32;
486 ptrs = sizeof(semid32);
487 } else {
488 #endif
489 semid = fd;
490 ptr = &semid;
491 ptrs = sizeof(semid);
492 compat32 = 0; /* silence gcc */
493 #ifdef COMPAT_FREEBSD32
494 }
495 #endif
496
497 return (copyout(ptr, semidp, ptrs));
498 }
499
500 /* Other helper routines. */
501 static int
502 ksem_create(struct thread *td, const char *name, semid_t *semidp, mode_t mode,
503 unsigned int value, int flags, int compat32)
504 {
505 struct filedesc *fdp;
506 struct ksem *ks;
507 struct file *fp;
508 char *path;
509 const char *pr_path;
510 size_t pr_pathlen;
511 Fnv32_t fnv;
512 int error, fd;
513
514 if (value > SEM_VALUE_MAX)
515 return (EINVAL);
516
517 fdp = td->td_proc->p_fd;
518 mode = (mode & ~fdp->fd_cmask) & ACCESSPERMS;
519 error = falloc(td, &fp, &fd, O_CLOEXEC);
520 if (error) {
521 if (name == NULL)
522 error = ENOSPC;
523 return (error);
524 }
525
526 /*
527 * Go ahead and copyout the file descriptor now. This is a bit
528 * premature, but it is a lot easier to handle errors as opposed
529 * to later when we've possibly created a new semaphore, etc.
530 */
531 error = ksem_create_copyout_semid(td, semidp, fd, compat32);
532 if (error) {
533 fdclose(fdp, fp, fd, td);
534 fdrop(fp, td);
535 return (error);
536 }
537
538 if (name == NULL) {
539 /* Create an anonymous semaphore. */
540 ks = ksem_alloc(td->td_ucred, mode, value);
541 if (ks == NULL)
542 error = ENOSPC;
543 else
544 ks->ks_flags |= KS_ANONYMOUS;
545 } else {
546 path = malloc(MAXPATHLEN, M_KSEM, M_WAITOK);
547 pr_path = td->td_ucred->cr_prison->pr_path;
548
549 /* Construct a full pathname for jailed callers. */
550 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0
551 : strlcpy(path, pr_path, MAXPATHLEN);
552 error = copyinstr(name, path + pr_pathlen,
553 MAXPATHLEN - pr_pathlen, NULL);
554
555 /* Require paths to start with a '/' character. */
556 if (error == 0 && path[pr_pathlen] != '/')
557 error = EINVAL;
558 if (error) {
559 fdclose(fdp, fp, fd, td);
560 fdrop(fp, td);
561 free(path, M_KSEM);
562 return (error);
563 }
564
565 fnv = fnv_32_str(path, FNV1_32_INIT);
566 sx_xlock(&ksem_dict_lock);
567 ks = ksem_lookup(path, fnv);
568 if (ks == NULL) {
569 /* Object does not exist, create it if requested. */
570 if (flags & O_CREAT) {
571 ks = ksem_alloc(td->td_ucred, mode, value);
572 if (ks == NULL)
573 error = ENFILE;
574 else {
575 ksem_insert(path, fnv, ks);
576 path = NULL;
577 }
578 } else
579 error = ENOENT;
580 } else {
581 /*
582 * Object already exists, obtain a new
583 * reference if requested and permitted.
584 */
585 if ((flags & (O_CREAT | O_EXCL)) ==
586 (O_CREAT | O_EXCL))
587 error = EEXIST;
588 else {
589 #ifdef MAC
590 error = mac_posixsem_check_open(td->td_ucred,
591 ks);
592 if (error == 0)
593 #endif
594 error = ksem_access(ks, td->td_ucred);
595 }
596 if (error == 0)
597 ksem_hold(ks);
598 #ifdef INVARIANTS
599 else
600 ks = NULL;
601 #endif
602 }
603 sx_xunlock(&ksem_dict_lock);
604 if (path)
605 free(path, M_KSEM);
606 }
607
608 if (error) {
609 KASSERT(ks == NULL, ("ksem_create error with a ksem"));
610 fdclose(fdp, fp, fd, td);
611 fdrop(fp, td);
612 return (error);
613 }
614 KASSERT(ks != NULL, ("ksem_create w/o a ksem"));
615
616 finit(fp, FREAD | FWRITE, DTYPE_SEM, ks, &ksem_ops);
617
618 fdrop(fp, td);
619
620 return (0);
621 }
622
623 static int
624 ksem_get(struct thread *td, semid_t id, cap_rights_t *rightsp,
625 struct file **fpp)
626 {
627 struct ksem *ks;
628 struct file *fp;
629 int error;
630
631 error = fget(td, id, rightsp, &fp);
632 if (error)
633 return (EINVAL);
634 if (fp->f_type != DTYPE_SEM) {
635 fdrop(fp, td);
636 return (EINVAL);
637 }
638 ks = fp->f_data;
639 if (ks->ks_flags & KS_DEAD) {
640 fdrop(fp, td);
641 return (EINVAL);
642 }
643 *fpp = fp;
644 return (0);
645 }
646
647 /* System calls. */
648 #ifndef _SYS_SYSPROTO_H_
649 struct ksem_init_args {
650 unsigned int value;
651 semid_t *idp;
652 };
653 #endif
654 int
655 sys_ksem_init(struct thread *td, struct ksem_init_args *uap)
656 {
657
658 return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value,
659 0, 0));
660 }
661
662 #ifndef _SYS_SYSPROTO_H_
663 struct ksem_open_args {
664 char *name;
665 int oflag;
666 mode_t mode;
667 unsigned int value;
668 semid_t *idp;
669 };
670 #endif
671 int
672 sys_ksem_open(struct thread *td, struct ksem_open_args *uap)
673 {
674
675 DP((">>> ksem_open start, pid=%d\n", (int)td->td_proc->p_pid));
676
677 if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0)
678 return (EINVAL);
679 return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value,
680 uap->oflag, 0));
681 }
682
683 #ifndef _SYS_SYSPROTO_H_
684 struct ksem_unlink_args {
685 char *name;
686 };
687 #endif
688 int
689 sys_ksem_unlink(struct thread *td, struct ksem_unlink_args *uap)
690 {
691 char *path;
692 const char *pr_path;
693 size_t pr_pathlen;
694 Fnv32_t fnv;
695 int error;
696
697 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
698 pr_path = td->td_ucred->cr_prison->pr_path;
699 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0
700 : strlcpy(path, pr_path, MAXPATHLEN);
701 error = copyinstr(uap->name, path + pr_pathlen, MAXPATHLEN - pr_pathlen,
702 NULL);
703 if (error) {
704 free(path, M_TEMP);
705 return (error);
706 }
707
708 fnv = fnv_32_str(path, FNV1_32_INIT);
709 sx_xlock(&ksem_dict_lock);
710 error = ksem_remove(path, fnv, td->td_ucred);
711 sx_xunlock(&ksem_dict_lock);
712 free(path, M_TEMP);
713
714 return (error);
715 }
716
717 #ifndef _SYS_SYSPROTO_H_
718 struct ksem_close_args {
719 semid_t id;
720 };
721 #endif
722 int
723 sys_ksem_close(struct thread *td, struct ksem_close_args *uap)
724 {
725 struct ksem *ks;
726 struct file *fp;
727 int error;
728
729 /* No capability rights required to close a semaphore. */
730 error = ksem_get(td, uap->id, 0, &fp);
731 if (error)
732 return (error);
733 ks = fp->f_data;
734 if (ks->ks_flags & KS_ANONYMOUS) {
735 fdrop(fp, td);
736 return (EINVAL);
737 }
738 error = kern_close(td, uap->id);
739 fdrop(fp, td);
740 return (error);
741 }
742
743 #ifndef _SYS_SYSPROTO_H_
744 struct ksem_post_args {
745 semid_t id;
746 };
747 #endif
748 int
749 sys_ksem_post(struct thread *td, struct ksem_post_args *uap)
750 {
751 cap_rights_t rights;
752 struct file *fp;
753 struct ksem *ks;
754 int error;
755
756 error = ksem_get(td, uap->id,
757 cap_rights_init(&rights, CAP_SEM_POST), &fp);
758 if (error)
759 return (error);
760 ks = fp->f_data;
761
762 mtx_lock(&sem_lock);
763 #ifdef MAC
764 error = mac_posixsem_check_post(td->td_ucred, fp->f_cred, ks);
765 if (error)
766 goto err;
767 #endif
768 if (ks->ks_value == SEM_VALUE_MAX) {
769 error = EOVERFLOW;
770 goto err;
771 }
772 ++ks->ks_value;
773 if (ks->ks_waiters > 0)
774 cv_signal(&ks->ks_cv);
775 error = 0;
776 vfs_timestamp(&ks->ks_ctime);
777 err:
778 mtx_unlock(&sem_lock);
779 fdrop(fp, td);
780 return (error);
781 }
782
783 #ifndef _SYS_SYSPROTO_H_
784 struct ksem_wait_args {
785 semid_t id;
786 };
787 #endif
788 int
789 sys_ksem_wait(struct thread *td, struct ksem_wait_args *uap)
790 {
791
792 return (kern_sem_wait(td, uap->id, 0, NULL));
793 }
794
795 #ifndef _SYS_SYSPROTO_H_
796 struct ksem_timedwait_args {
797 semid_t id;
798 const struct timespec *abstime;
799 };
800 #endif
801 int
802 sys_ksem_timedwait(struct thread *td, struct ksem_timedwait_args *uap)
803 {
804 struct timespec abstime;
805 struct timespec *ts;
806 int error;
807
808 /*
809 * We allow a null timespec (wait forever).
810 */
811 if (uap->abstime == NULL)
812 ts = NULL;
813 else {
814 error = copyin(uap->abstime, &abstime, sizeof(abstime));
815 if (error != 0)
816 return (error);
817 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0)
818 return (EINVAL);
819 ts = &abstime;
820 }
821 return (kern_sem_wait(td, uap->id, 0, ts));
822 }
823
824 #ifndef _SYS_SYSPROTO_H_
825 struct ksem_trywait_args {
826 semid_t id;
827 };
828 #endif
829 int
830 sys_ksem_trywait(struct thread *td, struct ksem_trywait_args *uap)
831 {
832
833 return (kern_sem_wait(td, uap->id, 1, NULL));
834 }
835
836 static int
837 kern_sem_wait(struct thread *td, semid_t id, int tryflag,
838 struct timespec *abstime)
839 {
840 struct timespec ts1, ts2;
841 struct timeval tv;
842 cap_rights_t rights;
843 struct file *fp;
844 struct ksem *ks;
845 int error;
846
847 DP((">>> kern_sem_wait entered! pid=%d\n", (int)td->td_proc->p_pid));
848 error = ksem_get(td, id, cap_rights_init(&rights, CAP_SEM_WAIT), &fp);
849 if (error)
850 return (error);
851 ks = fp->f_data;
852 mtx_lock(&sem_lock);
853 DP((">>> kern_sem_wait critical section entered! pid=%d\n",
854 (int)td->td_proc->p_pid));
855 #ifdef MAC
856 error = mac_posixsem_check_wait(td->td_ucred, fp->f_cred, ks);
857 if (error) {
858 DP(("kern_sem_wait mac failed\n"));
859 goto err;
860 }
861 #endif
862 DP(("kern_sem_wait value = %d, tryflag %d\n", ks->ks_value, tryflag));
863 vfs_timestamp(&ks->ks_atime);
864 while (ks->ks_value == 0) {
865 ks->ks_waiters++;
866 if (tryflag != 0)
867 error = EAGAIN;
868 else if (abstime == NULL)
869 error = cv_wait_sig(&ks->ks_cv, &sem_lock);
870 else {
871 for (;;) {
872 ts1 = *abstime;
873 getnanotime(&ts2);
874 timespecsub(&ts1, &ts2);
875 TIMESPEC_TO_TIMEVAL(&tv, &ts1);
876 if (tv.tv_sec < 0) {
877 error = ETIMEDOUT;
878 break;
879 }
880 error = cv_timedwait_sig(&ks->ks_cv,
881 &sem_lock, tvtohz(&tv));
882 if (error != EWOULDBLOCK)
883 break;
884 }
885 }
886 ks->ks_waiters--;
887 if (error)
888 goto err;
889 }
890 ks->ks_value--;
891 DP(("kern_sem_wait value post-decrement = %d\n", ks->ks_value));
892 error = 0;
893 err:
894 mtx_unlock(&sem_lock);
895 fdrop(fp, td);
896 DP(("<<< kern_sem_wait leaving, pid=%d, error = %d\n",
897 (int)td->td_proc->p_pid, error));
898 return (error);
899 }
900
901 #ifndef _SYS_SYSPROTO_H_
902 struct ksem_getvalue_args {
903 semid_t id;
904 int *val;
905 };
906 #endif
907 int
908 sys_ksem_getvalue(struct thread *td, struct ksem_getvalue_args *uap)
909 {
910 cap_rights_t rights;
911 struct file *fp;
912 struct ksem *ks;
913 int error, val;
914
915 error = ksem_get(td, uap->id,
916 cap_rights_init(&rights, CAP_SEM_GETVALUE), &fp);
917 if (error)
918 return (error);
919 ks = fp->f_data;
920
921 mtx_lock(&sem_lock);
922 #ifdef MAC
923 error = mac_posixsem_check_getvalue(td->td_ucred, fp->f_cred, ks);
924 if (error) {
925 mtx_unlock(&sem_lock);
926 fdrop(fp, td);
927 return (error);
928 }
929 #endif
930 val = ks->ks_value;
931 vfs_timestamp(&ks->ks_atime);
932 mtx_unlock(&sem_lock);
933 fdrop(fp, td);
934 error = copyout(&val, uap->val, sizeof(val));
935 return (error);
936 }
937
938 #ifndef _SYS_SYSPROTO_H_
939 struct ksem_destroy_args {
940 semid_t id;
941 };
942 #endif
943 int
944 sys_ksem_destroy(struct thread *td, struct ksem_destroy_args *uap)
945 {
946 struct file *fp;
947 struct ksem *ks;
948 int error;
949
950 /* No capability rights required to close a semaphore. */
951 error = ksem_get(td, uap->id, 0, &fp);
952 if (error)
953 return (error);
954 ks = fp->f_data;
955 if (!(ks->ks_flags & KS_ANONYMOUS)) {
956 fdrop(fp, td);
957 return (EINVAL);
958 }
959 mtx_lock(&sem_lock);
960 if (ks->ks_waiters != 0) {
961 mtx_unlock(&sem_lock);
962 error = EBUSY;
963 goto err;
964 }
965 ks->ks_flags |= KS_DEAD;
966 mtx_unlock(&sem_lock);
967
968 error = kern_close(td, uap->id);
969 err:
970 fdrop(fp, td);
971 return (error);
972 }
973
974 static struct syscall_helper_data ksem_syscalls[] = {
975 SYSCALL_INIT_HELPER(ksem_init),
976 SYSCALL_INIT_HELPER(ksem_open),
977 SYSCALL_INIT_HELPER(ksem_unlink),
978 SYSCALL_INIT_HELPER(ksem_close),
979 SYSCALL_INIT_HELPER(ksem_post),
980 SYSCALL_INIT_HELPER(ksem_wait),
981 SYSCALL_INIT_HELPER(ksem_timedwait),
982 SYSCALL_INIT_HELPER(ksem_trywait),
983 SYSCALL_INIT_HELPER(ksem_getvalue),
984 SYSCALL_INIT_HELPER(ksem_destroy),
985 SYSCALL_INIT_LAST
986 };
987
988 #ifdef COMPAT_FREEBSD32
989 #include <compat/freebsd32/freebsd32.h>
990 #include <compat/freebsd32/freebsd32_proto.h>
991 #include <compat/freebsd32/freebsd32_signal.h>
992 #include <compat/freebsd32/freebsd32_syscall.h>
993 #include <compat/freebsd32/freebsd32_util.h>
994
995 int
996 freebsd32_ksem_init(struct thread *td, struct freebsd32_ksem_init_args *uap)
997 {
998
999 return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value,
1000 0, 1));
1001 }
1002
1003 int
1004 freebsd32_ksem_open(struct thread *td, struct freebsd32_ksem_open_args *uap)
1005 {
1006
1007 if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0)
1008 return (EINVAL);
1009 return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value,
1010 uap->oflag, 1));
1011 }
1012
1013 int
1014 freebsd32_ksem_timedwait(struct thread *td,
1015 struct freebsd32_ksem_timedwait_args *uap)
1016 {
1017 struct timespec32 abstime32;
1018 struct timespec *ts, abstime;
1019 int error;
1020
1021 /*
1022 * We allow a null timespec (wait forever).
1023 */
1024 if (uap->abstime == NULL)
1025 ts = NULL;
1026 else {
1027 error = copyin(uap->abstime, &abstime32, sizeof(abstime32));
1028 if (error != 0)
1029 return (error);
1030 CP(abstime32, abstime, tv_sec);
1031 CP(abstime32, abstime, tv_nsec);
1032 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0)
1033 return (EINVAL);
1034 ts = &abstime;
1035 }
1036 return (kern_sem_wait(td, uap->id, 0, ts));
1037 }
1038
1039 static struct syscall_helper_data ksem32_syscalls[] = {
1040 SYSCALL32_INIT_HELPER(freebsd32_ksem_init),
1041 SYSCALL32_INIT_HELPER(freebsd32_ksem_open),
1042 SYSCALL32_INIT_HELPER_COMPAT(ksem_unlink),
1043 SYSCALL32_INIT_HELPER_COMPAT(ksem_close),
1044 SYSCALL32_INIT_HELPER_COMPAT(ksem_post),
1045 SYSCALL32_INIT_HELPER_COMPAT(ksem_wait),
1046 SYSCALL32_INIT_HELPER(freebsd32_ksem_timedwait),
1047 SYSCALL32_INIT_HELPER_COMPAT(ksem_trywait),
1048 SYSCALL32_INIT_HELPER_COMPAT(ksem_getvalue),
1049 SYSCALL32_INIT_HELPER_COMPAT(ksem_destroy),
1050 SYSCALL_INIT_LAST
1051 };
1052 #endif
1053
1054 static int
1055 ksem_module_init(void)
1056 {
1057 int error;
1058
1059 mtx_init(&sem_lock, "sem", NULL, MTX_DEF);
1060 mtx_init(&ksem_count_lock, "ksem count", NULL, MTX_DEF);
1061 sx_init(&ksem_dict_lock, "ksem dictionary");
1062 ksem_dictionary = hashinit(1024, M_KSEM, &ksem_hash);
1063 p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 200112L);
1064 p31b_setcfg(CTL_P1003_1B_SEM_NSEMS_MAX, SEM_MAX);
1065 p31b_setcfg(CTL_P1003_1B_SEM_VALUE_MAX, SEM_VALUE_MAX);
1066 ksem_info = ksem_info_impl;
1067
1068 error = syscall_helper_register(ksem_syscalls);
1069 if (error)
1070 return (error);
1071 #ifdef COMPAT_FREEBSD32
1072 error = syscall32_helper_register(ksem32_syscalls);
1073 if (error)
1074 return (error);
1075 #endif
1076 return (0);
1077 }
1078
1079 static void
1080 ksem_module_destroy(void)
1081 {
1082
1083 #ifdef COMPAT_FREEBSD32
1084 syscall32_helper_unregister(ksem32_syscalls);
1085 #endif
1086 syscall_helper_unregister(ksem_syscalls);
1087
1088 ksem_info = NULL;
1089 p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 0);
1090 hashdestroy(ksem_dictionary, M_KSEM, ksem_hash);
1091 sx_destroy(&ksem_dict_lock);
1092 mtx_destroy(&ksem_count_lock);
1093 mtx_destroy(&sem_lock);
1094 p31b_unsetcfg(CTL_P1003_1B_SEM_VALUE_MAX);
1095 p31b_unsetcfg(CTL_P1003_1B_SEM_NSEMS_MAX);
1096 }
1097
1098 static int
1099 sem_modload(struct module *module, int cmd, void *arg)
1100 {
1101 int error = 0;
1102
1103 switch (cmd) {
1104 case MOD_LOAD:
1105 error = ksem_module_init();
1106 if (error)
1107 ksem_module_destroy();
1108 break;
1109
1110 case MOD_UNLOAD:
1111 mtx_lock(&ksem_count_lock);
1112 if (nsems != 0) {
1113 error = EOPNOTSUPP;
1114 mtx_unlock(&ksem_count_lock);
1115 break;
1116 }
1117 ksem_dead = 1;
1118 mtx_unlock(&ksem_count_lock);
1119 ksem_module_destroy();
1120 break;
1121
1122 case MOD_SHUTDOWN:
1123 break;
1124 default:
1125 error = EINVAL;
1126 break;
1127 }
1128 return (error);
1129 }
1130
1131 static moduledata_t sem_mod = {
1132 "sem",
1133 &sem_modload,
1134 NULL
1135 };
1136
1137 DECLARE_MODULE(sem, sem_mod, SI_SUB_SYSV_SEM, SI_ORDER_FIRST);
1138 MODULE_VERSION(sem, 1);
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