FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_sem.c
1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2002 Alfred Perlstein <alfred@FreeBSD.org>
5 * Copyright (c) 2003-2005 SPARTA, Inc.
6 * Copyright (c) 2005, 2016-2017 Robert N. M. Watson
7 * All rights reserved.
8 *
9 * This software was developed for the FreeBSD Project in part by Network
10 * Associates Laboratories, the Security Research Division of Network
11 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"),
12 * as part of the DARPA CHATS research program.
13 *
14 * Portions of this software were developed by BAE Systems, the University of
15 * Cambridge Computer Laboratory, and Memorial University under DARPA/AFRL
16 * contract FA8650-15-C-7558 ("CADETS"), as part of the DARPA Transparent
17 * Computing (TC) research program.
18 *
19 * Redistribution and use in source and binary forms, with or without
20 * modification, are permitted provided that the following conditions
21 * are met:
22 * 1. Redistributions of source code must retain the above copyright
23 * notice, this list of conditions and the following disclaimer.
24 * 2. Redistributions in binary form must reproduce the above copyright
25 * notice, this list of conditions and the following disclaimer in the
26 * documentation and/or other materials provided with the distribution.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38 * SUCH DAMAGE.
39 */
40
41 #include <sys/cdefs.h>
42 __FBSDID("$FreeBSD: releng/12.0/sys/kern/uipc_sem.c 336914 2018-07-30 15:46:40Z asomers $");
43
44 #include "opt_posix.h"
45
46 #include <sys/param.h>
47 #include <sys/capsicum.h>
48 #include <sys/condvar.h>
49 #include <sys/fcntl.h>
50 #include <sys/file.h>
51 #include <sys/filedesc.h>
52 #include <sys/fnv_hash.h>
53 #include <sys/jail.h>
54 #include <sys/kernel.h>
55 #include <sys/ksem.h>
56 #include <sys/lock.h>
57 #include <sys/malloc.h>
58 #include <sys/module.h>
59 #include <sys/mutex.h>
60 #include <sys/priv.h>
61 #include <sys/proc.h>
62 #include <sys/posix4.h>
63 #include <sys/_semaphore.h>
64 #include <sys/stat.h>
65 #include <sys/syscall.h>
66 #include <sys/syscallsubr.h>
67 #include <sys/sysctl.h>
68 #include <sys/sysent.h>
69 #include <sys/sysproto.h>
70 #include <sys/systm.h>
71 #include <sys/sx.h>
72 #include <sys/user.h>
73 #include <sys/vnode.h>
74
75 #include <security/audit/audit.h>
76 #include <security/mac/mac_framework.h>
77
78 FEATURE(p1003_1b_semaphores, "POSIX P1003.1B semaphores support");
79 /*
80 * TODO
81 *
82 * - Resource limits?
83 * - Replace global sem_lock with mtx_pool locks?
84 * - Add a MAC check_create() hook for creating new named semaphores.
85 */
86
87 #ifndef SEM_MAX
88 #define SEM_MAX 30
89 #endif
90
91 #ifdef SEM_DEBUG
92 #define DP(x) printf x
93 #else
94 #define DP(x)
95 #endif
96
97 struct ksem_mapping {
98 char *km_path;
99 Fnv32_t km_fnv;
100 struct ksem *km_ksem;
101 LIST_ENTRY(ksem_mapping) km_link;
102 };
103
104 static MALLOC_DEFINE(M_KSEM, "ksem", "semaphore file descriptor");
105 static LIST_HEAD(, ksem_mapping) *ksem_dictionary;
106 static struct sx ksem_dict_lock;
107 static struct mtx ksem_count_lock;
108 static struct mtx sem_lock;
109 static u_long ksem_hash;
110 static int ksem_dead;
111
112 #define KSEM_HASH(fnv) (&ksem_dictionary[(fnv) & ksem_hash])
113
114 static int nsems = 0;
115 SYSCTL_DECL(_p1003_1b);
116 SYSCTL_INT(_p1003_1b, OID_AUTO, nsems, CTLFLAG_RD, &nsems, 0,
117 "Number of active kernel POSIX semaphores");
118
119 static int kern_sem_wait(struct thread *td, semid_t id, int tryflag,
120 struct timespec *abstime);
121 static int ksem_access(struct ksem *ks, struct ucred *ucred);
122 static struct ksem *ksem_alloc(struct ucred *ucred, mode_t mode,
123 unsigned int value);
124 static int ksem_create(struct thread *td, const char *path,
125 semid_t *semidp, mode_t mode, unsigned int value,
126 int flags, int compat32);
127 static void ksem_drop(struct ksem *ks);
128 static int ksem_get(struct thread *td, semid_t id, cap_rights_t *rightsp,
129 struct file **fpp);
130 static struct ksem *ksem_hold(struct ksem *ks);
131 static void ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks);
132 static struct ksem *ksem_lookup(char *path, Fnv32_t fnv);
133 static void ksem_module_destroy(void);
134 static int ksem_module_init(void);
135 static int ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred);
136 static int sem_modload(struct module *module, int cmd, void *arg);
137
138 static fo_stat_t ksem_stat;
139 static fo_close_t ksem_closef;
140 static fo_chmod_t ksem_chmod;
141 static fo_chown_t ksem_chown;
142 static fo_fill_kinfo_t ksem_fill_kinfo;
143
144 /* File descriptor operations. */
145 static struct fileops ksem_ops = {
146 .fo_read = invfo_rdwr,
147 .fo_write = invfo_rdwr,
148 .fo_truncate = invfo_truncate,
149 .fo_ioctl = invfo_ioctl,
150 .fo_poll = invfo_poll,
151 .fo_kqfilter = invfo_kqfilter,
152 .fo_stat = ksem_stat,
153 .fo_close = ksem_closef,
154 .fo_chmod = ksem_chmod,
155 .fo_chown = ksem_chown,
156 .fo_sendfile = invfo_sendfile,
157 .fo_fill_kinfo = ksem_fill_kinfo,
158 .fo_flags = DFLAG_PASSABLE
159 };
160
161 FEATURE(posix_sem, "POSIX semaphores");
162
163 static int
164 ksem_stat(struct file *fp, struct stat *sb, struct ucred *active_cred,
165 struct thread *td)
166 {
167 struct ksem *ks;
168 #ifdef MAC
169 int error;
170 #endif
171
172 ks = fp->f_data;
173
174 #ifdef MAC
175 error = mac_posixsem_check_stat(active_cred, fp->f_cred, ks);
176 if (error)
177 return (error);
178 #endif
179
180 /*
181 * Attempt to return sanish values for fstat() on a semaphore
182 * file descriptor.
183 */
184 bzero(sb, sizeof(*sb));
185
186 mtx_lock(&sem_lock);
187 sb->st_atim = ks->ks_atime;
188 sb->st_ctim = ks->ks_ctime;
189 sb->st_mtim = ks->ks_mtime;
190 sb->st_birthtim = ks->ks_birthtime;
191 sb->st_uid = ks->ks_uid;
192 sb->st_gid = ks->ks_gid;
193 sb->st_mode = S_IFREG | ks->ks_mode; /* XXX */
194 mtx_unlock(&sem_lock);
195
196 return (0);
197 }
198
199 static int
200 ksem_chmod(struct file *fp, mode_t mode, struct ucred *active_cred,
201 struct thread *td)
202 {
203 struct ksem *ks;
204 int error;
205
206 error = 0;
207 ks = fp->f_data;
208 mtx_lock(&sem_lock);
209 #ifdef MAC
210 error = mac_posixsem_check_setmode(active_cred, ks, mode);
211 if (error != 0)
212 goto out;
213 #endif
214 error = vaccess(VREG, ks->ks_mode, ks->ks_uid, ks->ks_gid, VADMIN,
215 active_cred, NULL);
216 if (error != 0)
217 goto out;
218 ks->ks_mode = mode & ACCESSPERMS;
219 out:
220 mtx_unlock(&sem_lock);
221 return (error);
222 }
223
224 static int
225 ksem_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
226 struct thread *td)
227 {
228 struct ksem *ks;
229 int error;
230
231 error = 0;
232 ks = fp->f_data;
233 mtx_lock(&sem_lock);
234 #ifdef MAC
235 error = mac_posixsem_check_setowner(active_cred, ks, uid, gid);
236 if (error != 0)
237 goto out;
238 #endif
239 if (uid == (uid_t)-1)
240 uid = ks->ks_uid;
241 if (gid == (gid_t)-1)
242 gid = ks->ks_gid;
243 if (((uid != ks->ks_uid && uid != active_cred->cr_uid) ||
244 (gid != ks->ks_gid && !groupmember(gid, active_cred))) &&
245 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN, 0)))
246 goto out;
247 ks->ks_uid = uid;
248 ks->ks_gid = gid;
249 out:
250 mtx_unlock(&sem_lock);
251 return (error);
252 }
253
254 static int
255 ksem_closef(struct file *fp, struct thread *td)
256 {
257 struct ksem *ks;
258
259 ks = fp->f_data;
260 fp->f_data = NULL;
261 ksem_drop(ks);
262
263 return (0);
264 }
265
266 static int
267 ksem_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp)
268 {
269 const char *path, *pr_path;
270 struct ksem *ks;
271 size_t pr_pathlen;
272
273 kif->kf_type = KF_TYPE_SEM;
274 ks = fp->f_data;
275 mtx_lock(&sem_lock);
276 kif->kf_un.kf_sem.kf_sem_value = ks->ks_value;
277 kif->kf_un.kf_sem.kf_sem_mode = S_IFREG | ks->ks_mode; /* XXX */
278 mtx_unlock(&sem_lock);
279 if (ks->ks_path != NULL) {
280 sx_slock(&ksem_dict_lock);
281 if (ks->ks_path != NULL) {
282 path = ks->ks_path;
283 pr_path = curthread->td_ucred->cr_prison->pr_path;
284 if (strcmp(pr_path, "/") != 0) {
285 /* Return the jail-rooted pathname. */
286 pr_pathlen = strlen(pr_path);
287 if (strncmp(path, pr_path, pr_pathlen) == 0 &&
288 path[pr_pathlen] == '/')
289 path += pr_pathlen;
290 }
291 strlcpy(kif->kf_path, path, sizeof(kif->kf_path));
292 }
293 sx_sunlock(&ksem_dict_lock);
294 }
295 return (0);
296 }
297
298 /*
299 * ksem object management including creation and reference counting
300 * routines.
301 */
302 static struct ksem *
303 ksem_alloc(struct ucred *ucred, mode_t mode, unsigned int value)
304 {
305 struct ksem *ks;
306
307 mtx_lock(&ksem_count_lock);
308 if (nsems == p31b_getcfg(CTL_P1003_1B_SEM_NSEMS_MAX) || ksem_dead) {
309 mtx_unlock(&ksem_count_lock);
310 return (NULL);
311 }
312 nsems++;
313 mtx_unlock(&ksem_count_lock);
314 ks = malloc(sizeof(*ks), M_KSEM, M_WAITOK | M_ZERO);
315 ks->ks_uid = ucred->cr_uid;
316 ks->ks_gid = ucred->cr_gid;
317 ks->ks_mode = mode;
318 ks->ks_value = value;
319 cv_init(&ks->ks_cv, "ksem");
320 vfs_timestamp(&ks->ks_birthtime);
321 ks->ks_atime = ks->ks_mtime = ks->ks_ctime = ks->ks_birthtime;
322 refcount_init(&ks->ks_ref, 1);
323 #ifdef MAC
324 mac_posixsem_init(ks);
325 mac_posixsem_create(ucred, ks);
326 #endif
327
328 return (ks);
329 }
330
331 static struct ksem *
332 ksem_hold(struct ksem *ks)
333 {
334
335 refcount_acquire(&ks->ks_ref);
336 return (ks);
337 }
338
339 static void
340 ksem_drop(struct ksem *ks)
341 {
342
343 if (refcount_release(&ks->ks_ref)) {
344 #ifdef MAC
345 mac_posixsem_destroy(ks);
346 #endif
347 cv_destroy(&ks->ks_cv);
348 free(ks, M_KSEM);
349 mtx_lock(&ksem_count_lock);
350 nsems--;
351 mtx_unlock(&ksem_count_lock);
352 }
353 }
354
355 /*
356 * Determine if the credentials have sufficient permissions for read
357 * and write access.
358 */
359 static int
360 ksem_access(struct ksem *ks, struct ucred *ucred)
361 {
362 int error;
363
364 error = vaccess(VREG, ks->ks_mode, ks->ks_uid, ks->ks_gid,
365 VREAD | VWRITE, ucred, NULL);
366 if (error)
367 error = priv_check_cred(ucred, PRIV_SEM_WRITE, 0);
368 return (error);
369 }
370
371 /*
372 * Dictionary management. We maintain an in-kernel dictionary to map
373 * paths to semaphore objects. We use the FNV hash on the path to
374 * store the mappings in a hash table.
375 */
376 static struct ksem *
377 ksem_lookup(char *path, Fnv32_t fnv)
378 {
379 struct ksem_mapping *map;
380
381 LIST_FOREACH(map, KSEM_HASH(fnv), km_link) {
382 if (map->km_fnv != fnv)
383 continue;
384 if (strcmp(map->km_path, path) == 0)
385 return (map->km_ksem);
386 }
387
388 return (NULL);
389 }
390
391 static void
392 ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks)
393 {
394 struct ksem_mapping *map;
395
396 map = malloc(sizeof(struct ksem_mapping), M_KSEM, M_WAITOK);
397 map->km_path = path;
398 map->km_fnv = fnv;
399 map->km_ksem = ksem_hold(ks);
400 ks->ks_path = path;
401 LIST_INSERT_HEAD(KSEM_HASH(fnv), map, km_link);
402 }
403
404 static int
405 ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred)
406 {
407 struct ksem_mapping *map;
408 int error;
409
410 LIST_FOREACH(map, KSEM_HASH(fnv), km_link) {
411 if (map->km_fnv != fnv)
412 continue;
413 if (strcmp(map->km_path, path) == 0) {
414 #ifdef MAC
415 error = mac_posixsem_check_unlink(ucred, map->km_ksem);
416 if (error)
417 return (error);
418 #endif
419 error = ksem_access(map->km_ksem, ucred);
420 if (error)
421 return (error);
422 map->km_ksem->ks_path = NULL;
423 LIST_REMOVE(map, km_link);
424 ksem_drop(map->km_ksem);
425 free(map->km_path, M_KSEM);
426 free(map, M_KSEM);
427 return (0);
428 }
429 }
430
431 return (ENOENT);
432 }
433
434 static int
435 ksem_create_copyout_semid(struct thread *td, semid_t *semidp, int fd,
436 int compat32)
437 {
438 semid_t semid;
439 #ifdef COMPAT_FREEBSD32
440 int32_t semid32;
441 #endif
442 void *ptr;
443 size_t ptrs;
444
445 #ifdef COMPAT_FREEBSD32
446 if (compat32) {
447 semid32 = fd;
448 ptr = &semid32;
449 ptrs = sizeof(semid32);
450 } else {
451 #endif
452 semid = fd;
453 ptr = &semid;
454 ptrs = sizeof(semid);
455 compat32 = 0; /* silence gcc */
456 #ifdef COMPAT_FREEBSD32
457 }
458 #endif
459
460 return (copyout(ptr, semidp, ptrs));
461 }
462
463 /* Other helper routines. */
464 static int
465 ksem_create(struct thread *td, const char *name, semid_t *semidp, mode_t mode,
466 unsigned int value, int flags, int compat32)
467 {
468 struct filedesc *fdp;
469 struct ksem *ks;
470 struct file *fp;
471 char *path;
472 const char *pr_path;
473 size_t pr_pathlen;
474 Fnv32_t fnv;
475 int error, fd;
476
477 AUDIT_ARG_FFLAGS(flags);
478 AUDIT_ARG_MODE(mode);
479 AUDIT_ARG_VALUE(value);
480
481 if (value > SEM_VALUE_MAX)
482 return (EINVAL);
483
484 fdp = td->td_proc->p_fd;
485 mode = (mode & ~fdp->fd_cmask) & ACCESSPERMS;
486 error = falloc(td, &fp, &fd, O_CLOEXEC);
487 if (error) {
488 if (name == NULL)
489 error = ENOSPC;
490 return (error);
491 }
492
493 /*
494 * Go ahead and copyout the file descriptor now. This is a bit
495 * premature, but it is a lot easier to handle errors as opposed
496 * to later when we've possibly created a new semaphore, etc.
497 */
498 error = ksem_create_copyout_semid(td, semidp, fd, compat32);
499 if (error) {
500 fdclose(td, fp, fd);
501 fdrop(fp, td);
502 return (error);
503 }
504
505 if (name == NULL) {
506 /* Create an anonymous semaphore. */
507 ks = ksem_alloc(td->td_ucred, mode, value);
508 if (ks == NULL)
509 error = ENOSPC;
510 else
511 ks->ks_flags |= KS_ANONYMOUS;
512 } else {
513 path = malloc(MAXPATHLEN, M_KSEM, M_WAITOK);
514 pr_path = td->td_ucred->cr_prison->pr_path;
515
516 /* Construct a full pathname for jailed callers. */
517 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0
518 : strlcpy(path, pr_path, MAXPATHLEN);
519 error = copyinstr(name, path + pr_pathlen,
520 MAXPATHLEN - pr_pathlen, NULL);
521
522 /* Require paths to start with a '/' character. */
523 if (error == 0 && path[pr_pathlen] != '/')
524 error = EINVAL;
525 if (error) {
526 fdclose(td, fp, fd);
527 fdrop(fp, td);
528 free(path, M_KSEM);
529 return (error);
530 }
531
532 AUDIT_ARG_UPATH1_CANON(path);
533 fnv = fnv_32_str(path, FNV1_32_INIT);
534 sx_xlock(&ksem_dict_lock);
535 ks = ksem_lookup(path, fnv);
536 if (ks == NULL) {
537 /* Object does not exist, create it if requested. */
538 if (flags & O_CREAT) {
539 ks = ksem_alloc(td->td_ucred, mode, value);
540 if (ks == NULL)
541 error = ENFILE;
542 else {
543 ksem_insert(path, fnv, ks);
544 path = NULL;
545 }
546 } else
547 error = ENOENT;
548 } else {
549 /*
550 * Object already exists, obtain a new
551 * reference if requested and permitted.
552 */
553 if ((flags & (O_CREAT | O_EXCL)) ==
554 (O_CREAT | O_EXCL))
555 error = EEXIST;
556 else {
557 #ifdef MAC
558 error = mac_posixsem_check_open(td->td_ucred,
559 ks);
560 if (error == 0)
561 #endif
562 error = ksem_access(ks, td->td_ucred);
563 }
564 if (error == 0)
565 ksem_hold(ks);
566 #ifdef INVARIANTS
567 else
568 ks = NULL;
569 #endif
570 }
571 sx_xunlock(&ksem_dict_lock);
572 if (path)
573 free(path, M_KSEM);
574 }
575
576 if (error) {
577 KASSERT(ks == NULL, ("ksem_create error with a ksem"));
578 fdclose(td, fp, fd);
579 fdrop(fp, td);
580 return (error);
581 }
582 KASSERT(ks != NULL, ("ksem_create w/o a ksem"));
583
584 finit(fp, FREAD | FWRITE, DTYPE_SEM, ks, &ksem_ops);
585
586 fdrop(fp, td);
587
588 return (0);
589 }
590
591 static int
592 ksem_get(struct thread *td, semid_t id, cap_rights_t *rightsp,
593 struct file **fpp)
594 {
595 struct ksem *ks;
596 struct file *fp;
597 int error;
598
599 error = fget(td, id, rightsp, &fp);
600 if (error)
601 return (EINVAL);
602 if (fp->f_type != DTYPE_SEM) {
603 fdrop(fp, td);
604 return (EINVAL);
605 }
606 ks = fp->f_data;
607 if (ks->ks_flags & KS_DEAD) {
608 fdrop(fp, td);
609 return (EINVAL);
610 }
611 *fpp = fp;
612 return (0);
613 }
614
615 /* System calls. */
616 #ifndef _SYS_SYSPROTO_H_
617 struct ksem_init_args {
618 unsigned int value;
619 semid_t *idp;
620 };
621 #endif
622 int
623 sys_ksem_init(struct thread *td, struct ksem_init_args *uap)
624 {
625
626 return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value,
627 0, 0));
628 }
629
630 #ifndef _SYS_SYSPROTO_H_
631 struct ksem_open_args {
632 char *name;
633 int oflag;
634 mode_t mode;
635 unsigned int value;
636 semid_t *idp;
637 };
638 #endif
639 int
640 sys_ksem_open(struct thread *td, struct ksem_open_args *uap)
641 {
642
643 DP((">>> ksem_open start, pid=%d\n", (int)td->td_proc->p_pid));
644
645 if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0)
646 return (EINVAL);
647 return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value,
648 uap->oflag, 0));
649 }
650
651 #ifndef _SYS_SYSPROTO_H_
652 struct ksem_unlink_args {
653 char *name;
654 };
655 #endif
656 int
657 sys_ksem_unlink(struct thread *td, struct ksem_unlink_args *uap)
658 {
659 char *path;
660 const char *pr_path;
661 size_t pr_pathlen;
662 Fnv32_t fnv;
663 int error;
664
665 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
666 pr_path = td->td_ucred->cr_prison->pr_path;
667 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0
668 : strlcpy(path, pr_path, MAXPATHLEN);
669 error = copyinstr(uap->name, path + pr_pathlen, MAXPATHLEN - pr_pathlen,
670 NULL);
671 if (error) {
672 free(path, M_TEMP);
673 return (error);
674 }
675
676 AUDIT_ARG_UPATH1_CANON(path);
677 fnv = fnv_32_str(path, FNV1_32_INIT);
678 sx_xlock(&ksem_dict_lock);
679 error = ksem_remove(path, fnv, td->td_ucred);
680 sx_xunlock(&ksem_dict_lock);
681 free(path, M_TEMP);
682
683 return (error);
684 }
685
686 #ifndef _SYS_SYSPROTO_H_
687 struct ksem_close_args {
688 semid_t id;
689 };
690 #endif
691 int
692 sys_ksem_close(struct thread *td, struct ksem_close_args *uap)
693 {
694 struct ksem *ks;
695 struct file *fp;
696 int error;
697
698 /* No capability rights required to close a semaphore. */
699 AUDIT_ARG_FD(uap->id);
700 error = ksem_get(td, uap->id, &cap_no_rights, &fp);
701 if (error)
702 return (error);
703 ks = fp->f_data;
704 if (ks->ks_flags & KS_ANONYMOUS) {
705 fdrop(fp, td);
706 return (EINVAL);
707 }
708 error = kern_close(td, uap->id);
709 fdrop(fp, td);
710 return (error);
711 }
712
713 #ifndef _SYS_SYSPROTO_H_
714 struct ksem_post_args {
715 semid_t id;
716 };
717 #endif
718 int
719 sys_ksem_post(struct thread *td, struct ksem_post_args *uap)
720 {
721 cap_rights_t rights;
722 struct file *fp;
723 struct ksem *ks;
724 int error;
725
726 AUDIT_ARG_FD(uap->id);
727 error = ksem_get(td, uap->id,
728 cap_rights_init(&rights, CAP_SEM_POST), &fp);
729 if (error)
730 return (error);
731 ks = fp->f_data;
732
733 mtx_lock(&sem_lock);
734 #ifdef MAC
735 error = mac_posixsem_check_post(td->td_ucred, fp->f_cred, ks);
736 if (error)
737 goto err;
738 #endif
739 if (ks->ks_value == SEM_VALUE_MAX) {
740 error = EOVERFLOW;
741 goto err;
742 }
743 ++ks->ks_value;
744 if (ks->ks_waiters > 0)
745 cv_signal(&ks->ks_cv);
746 error = 0;
747 vfs_timestamp(&ks->ks_ctime);
748 err:
749 mtx_unlock(&sem_lock);
750 fdrop(fp, td);
751 return (error);
752 }
753
754 #ifndef _SYS_SYSPROTO_H_
755 struct ksem_wait_args {
756 semid_t id;
757 };
758 #endif
759 int
760 sys_ksem_wait(struct thread *td, struct ksem_wait_args *uap)
761 {
762
763 return (kern_sem_wait(td, uap->id, 0, NULL));
764 }
765
766 #ifndef _SYS_SYSPROTO_H_
767 struct ksem_timedwait_args {
768 semid_t id;
769 const struct timespec *abstime;
770 };
771 #endif
772 int
773 sys_ksem_timedwait(struct thread *td, struct ksem_timedwait_args *uap)
774 {
775 struct timespec abstime;
776 struct timespec *ts;
777 int error;
778
779 /*
780 * We allow a null timespec (wait forever).
781 */
782 if (uap->abstime == NULL)
783 ts = NULL;
784 else {
785 error = copyin(uap->abstime, &abstime, sizeof(abstime));
786 if (error != 0)
787 return (error);
788 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0)
789 return (EINVAL);
790 ts = &abstime;
791 }
792 return (kern_sem_wait(td, uap->id, 0, ts));
793 }
794
795 #ifndef _SYS_SYSPROTO_H_
796 struct ksem_trywait_args {
797 semid_t id;
798 };
799 #endif
800 int
801 sys_ksem_trywait(struct thread *td, struct ksem_trywait_args *uap)
802 {
803
804 return (kern_sem_wait(td, uap->id, 1, NULL));
805 }
806
807 static int
808 kern_sem_wait(struct thread *td, semid_t id, int tryflag,
809 struct timespec *abstime)
810 {
811 struct timespec ts1, ts2;
812 struct timeval tv;
813 cap_rights_t rights;
814 struct file *fp;
815 struct ksem *ks;
816 int error;
817
818 DP((">>> kern_sem_wait entered! pid=%d\n", (int)td->td_proc->p_pid));
819 AUDIT_ARG_FD(id);
820 error = ksem_get(td, id, cap_rights_init(&rights, CAP_SEM_WAIT), &fp);
821 if (error)
822 return (error);
823 ks = fp->f_data;
824 mtx_lock(&sem_lock);
825 DP((">>> kern_sem_wait critical section entered! pid=%d\n",
826 (int)td->td_proc->p_pid));
827 #ifdef MAC
828 error = mac_posixsem_check_wait(td->td_ucred, fp->f_cred, ks);
829 if (error) {
830 DP(("kern_sem_wait mac failed\n"));
831 goto err;
832 }
833 #endif
834 DP(("kern_sem_wait value = %d, tryflag %d\n", ks->ks_value, tryflag));
835 vfs_timestamp(&ks->ks_atime);
836 while (ks->ks_value == 0) {
837 ks->ks_waiters++;
838 if (tryflag != 0)
839 error = EAGAIN;
840 else if (abstime == NULL)
841 error = cv_wait_sig(&ks->ks_cv, &sem_lock);
842 else {
843 for (;;) {
844 ts1 = *abstime;
845 getnanotime(&ts2);
846 timespecsub(&ts1, &ts2, &ts1);
847 TIMESPEC_TO_TIMEVAL(&tv, &ts1);
848 if (tv.tv_sec < 0) {
849 error = ETIMEDOUT;
850 break;
851 }
852 error = cv_timedwait_sig(&ks->ks_cv,
853 &sem_lock, tvtohz(&tv));
854 if (error != EWOULDBLOCK)
855 break;
856 }
857 }
858 ks->ks_waiters--;
859 if (error)
860 goto err;
861 }
862 ks->ks_value--;
863 DP(("kern_sem_wait value post-decrement = %d\n", ks->ks_value));
864 error = 0;
865 err:
866 mtx_unlock(&sem_lock);
867 fdrop(fp, td);
868 DP(("<<< kern_sem_wait leaving, pid=%d, error = %d\n",
869 (int)td->td_proc->p_pid, error));
870 return (error);
871 }
872
873 #ifndef _SYS_SYSPROTO_H_
874 struct ksem_getvalue_args {
875 semid_t id;
876 int *val;
877 };
878 #endif
879 int
880 sys_ksem_getvalue(struct thread *td, struct ksem_getvalue_args *uap)
881 {
882 cap_rights_t rights;
883 struct file *fp;
884 struct ksem *ks;
885 int error, val;
886
887 AUDIT_ARG_FD(uap->id);
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 AUDIT_ARG_FD(uap->id);
925 error = ksem_get(td, uap->id, &cap_no_rights, &fp);
926 if (error)
927 return (error);
928 ks = fp->f_data;
929 if (!(ks->ks_flags & KS_ANONYMOUS)) {
930 fdrop(fp, td);
931 return (EINVAL);
932 }
933 mtx_lock(&sem_lock);
934 if (ks->ks_waiters != 0) {
935 mtx_unlock(&sem_lock);
936 error = EBUSY;
937 goto err;
938 }
939 ks->ks_flags |= KS_DEAD;
940 mtx_unlock(&sem_lock);
941
942 error = kern_close(td, uap->id);
943 err:
944 fdrop(fp, td);
945 return (error);
946 }
947
948 static struct syscall_helper_data ksem_syscalls[] = {
949 SYSCALL_INIT_HELPER(ksem_init),
950 SYSCALL_INIT_HELPER(ksem_open),
951 SYSCALL_INIT_HELPER(ksem_unlink),
952 SYSCALL_INIT_HELPER(ksem_close),
953 SYSCALL_INIT_HELPER(ksem_post),
954 SYSCALL_INIT_HELPER(ksem_wait),
955 SYSCALL_INIT_HELPER(ksem_timedwait),
956 SYSCALL_INIT_HELPER(ksem_trywait),
957 SYSCALL_INIT_HELPER(ksem_getvalue),
958 SYSCALL_INIT_HELPER(ksem_destroy),
959 SYSCALL_INIT_LAST
960 };
961
962 #ifdef COMPAT_FREEBSD32
963 #include <compat/freebsd32/freebsd32.h>
964 #include <compat/freebsd32/freebsd32_proto.h>
965 #include <compat/freebsd32/freebsd32_signal.h>
966 #include <compat/freebsd32/freebsd32_syscall.h>
967 #include <compat/freebsd32/freebsd32_util.h>
968
969 int
970 freebsd32_ksem_init(struct thread *td, struct freebsd32_ksem_init_args *uap)
971 {
972
973 return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value,
974 0, 1));
975 }
976
977 int
978 freebsd32_ksem_open(struct thread *td, struct freebsd32_ksem_open_args *uap)
979 {
980
981 if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0)
982 return (EINVAL);
983 return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value,
984 uap->oflag, 1));
985 }
986
987 int
988 freebsd32_ksem_timedwait(struct thread *td,
989 struct freebsd32_ksem_timedwait_args *uap)
990 {
991 struct timespec32 abstime32;
992 struct timespec *ts, abstime;
993 int error;
994
995 /*
996 * We allow a null timespec (wait forever).
997 */
998 if (uap->abstime == NULL)
999 ts = NULL;
1000 else {
1001 error = copyin(uap->abstime, &abstime32, sizeof(abstime32));
1002 if (error != 0)
1003 return (error);
1004 CP(abstime32, abstime, tv_sec);
1005 CP(abstime32, abstime, tv_nsec);
1006 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0)
1007 return (EINVAL);
1008 ts = &abstime;
1009 }
1010 return (kern_sem_wait(td, uap->id, 0, ts));
1011 }
1012
1013 static struct syscall_helper_data ksem32_syscalls[] = {
1014 SYSCALL32_INIT_HELPER(freebsd32_ksem_init),
1015 SYSCALL32_INIT_HELPER(freebsd32_ksem_open),
1016 SYSCALL32_INIT_HELPER_COMPAT(ksem_unlink),
1017 SYSCALL32_INIT_HELPER_COMPAT(ksem_close),
1018 SYSCALL32_INIT_HELPER_COMPAT(ksem_post),
1019 SYSCALL32_INIT_HELPER_COMPAT(ksem_wait),
1020 SYSCALL32_INIT_HELPER(freebsd32_ksem_timedwait),
1021 SYSCALL32_INIT_HELPER_COMPAT(ksem_trywait),
1022 SYSCALL32_INIT_HELPER_COMPAT(ksem_getvalue),
1023 SYSCALL32_INIT_HELPER_COMPAT(ksem_destroy),
1024 SYSCALL_INIT_LAST
1025 };
1026 #endif
1027
1028 static int
1029 ksem_module_init(void)
1030 {
1031 int error;
1032
1033 mtx_init(&sem_lock, "sem", NULL, MTX_DEF);
1034 mtx_init(&ksem_count_lock, "ksem count", NULL, MTX_DEF);
1035 sx_init(&ksem_dict_lock, "ksem dictionary");
1036 ksem_dictionary = hashinit(1024, M_KSEM, &ksem_hash);
1037 p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 200112L);
1038 p31b_setcfg(CTL_P1003_1B_SEM_NSEMS_MAX, SEM_MAX);
1039 p31b_setcfg(CTL_P1003_1B_SEM_VALUE_MAX, SEM_VALUE_MAX);
1040
1041 error = syscall_helper_register(ksem_syscalls, SY_THR_STATIC_KLD);
1042 if (error)
1043 return (error);
1044 #ifdef COMPAT_FREEBSD32
1045 error = syscall32_helper_register(ksem32_syscalls, SY_THR_STATIC_KLD);
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 p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 0);
1062 hashdestroy(ksem_dictionary, M_KSEM, ksem_hash);
1063 sx_destroy(&ksem_dict_lock);
1064 mtx_destroy(&ksem_count_lock);
1065 mtx_destroy(&sem_lock);
1066 p31b_unsetcfg(CTL_P1003_1B_SEM_VALUE_MAX);
1067 p31b_unsetcfg(CTL_P1003_1B_SEM_NSEMS_MAX);
1068 }
1069
1070 static int
1071 sem_modload(struct module *module, int cmd, void *arg)
1072 {
1073 int error = 0;
1074
1075 switch (cmd) {
1076 case MOD_LOAD:
1077 error = ksem_module_init();
1078 if (error)
1079 ksem_module_destroy();
1080 break;
1081
1082 case MOD_UNLOAD:
1083 mtx_lock(&ksem_count_lock);
1084 if (nsems != 0) {
1085 error = EOPNOTSUPP;
1086 mtx_unlock(&ksem_count_lock);
1087 break;
1088 }
1089 ksem_dead = 1;
1090 mtx_unlock(&ksem_count_lock);
1091 ksem_module_destroy();
1092 break;
1093
1094 case MOD_SHUTDOWN:
1095 break;
1096 default:
1097 error = EINVAL;
1098 break;
1099 }
1100 return (error);
1101 }
1102
1103 static moduledata_t sem_mod = {
1104 "sem",
1105 &sem_modload,
1106 NULL
1107 };
1108
1109 DECLARE_MODULE(sem, sem_mod, SI_SUB_SYSV_SEM, SI_ORDER_FIRST);
1110 MODULE_VERSION(sem, 1);
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