1 /*
2 * Copyright (c) 2000-2007 Apple Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28 /*
29 * Copyright (c) 1990, 1996-1998 Apple Computer, Inc.
30 * All Rights Reserved.
31 */
32 /*
33 * posix_sem.c : Support for POSIX semaphore APIs
34 *
35 * File: posix_sem.c
36 * Author: Ananthakrishna Ramesh
37 *
38 * HISTORY
39 * 2-Sep-1999 A.Ramesh
40 * Created for MacOSX
41 *
42 */
43 /*
44 * NOTICE: This file was modified by SPARTA, Inc. in 2005 to introduce
45 * support for mandatory and extensible security protections. This notice
46 * is included in support of clause 2.2 (b) of the Apple Public License,
47 * Version 2.0.
48 */
49
50 #include <sys/cdefs.h>
51 #include <sys/param.h>
52 #include <sys/systm.h>
53 #include <sys/kernel.h>
54 #include <sys/file_internal.h>
55 #include <sys/filedesc.h>
56 #include <sys/stat.h>
57 #include <sys/proc_internal.h>
58 #include <sys/kauth.h>
59 #include <sys/mount.h>
60 #include <sys/namei.h>
61 #include <sys/vnode.h>
62 #include <sys/ioctl.h>
63 #include <sys/tty.h>
64 #include <sys/malloc.h>
65 #include <sys/semaphore.h>
66 #include <sys/sysproto.h>
67 #include <sys/proc_info.h>
68
69 #if CONFIG_MACF
70 #include <sys/vnode_internal.h>
71 #include <security/mac_framework.h>
72 #endif
73
74 #include <security/audit/audit.h>
75
76 #include <mach/mach_types.h>
77 #include <mach/vm_prot.h>
78 #include <mach/semaphore.h>
79 #include <mach/sync_policy.h>
80 #include <mach/task.h>
81 #include <kern/kern_types.h>
82 #include <kern/task.h>
83 #include <kern/clock.h>
84 #include <mach/kern_return.h>
85
86 #define f_flag fp_glob->fg_flag
87 #define f_ops fp_glob->fg_ops
88
89 #define PSEMNAMLEN 31 /* maximum name segment length we bother with */
90
91 struct pseminfo {
92 unsigned int psem_flags;
93 unsigned int psem_usecount;
94 mode_t psem_mode;
95 uid_t psem_uid;
96 gid_t psem_gid;
97 char psem_name[PSEMNAMLEN + 1]; /* segment name */
98 semaphore_t psem_semobject;
99 struct label * psem_label;
100 pid_t psem_creator_pid;
101 uint64_t psem_creator_uniqueid;
102 };
103 #define PSEMINFO_NULL (struct pseminfo *)0
104
105 #define PSEM_NONE 1
106 #define PSEM_DEFINED 2
107 #define PSEM_ALLOCATED 4
108 #define PSEM_MAPPED 8
109 #define PSEM_INUSE 0x10
110 #define PSEM_REMOVED 0x20
111 #define PSEM_INCREATE 0x40
112 #define PSEM_INDELETE 0x80
113
114 struct psemcache {
115 LIST_ENTRY(psemcache) psem_hash; /* hash chain */
116 struct pseminfo *pseminfo; /* vnode the name refers to */
117 size_t psem_nlen; /* length of name */
118 char psem_name[PSEMNAMLEN + 1]; /* segment name */
119 };
120 #define PSEMCACHE_NULL (struct psemcache *)0
121
122 #define PSEMCACHE_NOTFOUND (0)
123 #define PSEMCACHE_FOUND (-1)
124 #define PSEMCACHE_NEGATIVE (ENOENT)
125
126 struct psemstats {
127 long goodhits; /* hits that we can really use */
128 long neghits; /* negative hits that we can use */
129 long badhits; /* hits we must drop */
130 long falsehits; /* hits with id mismatch */
131 long miss; /* misses */
132 long longnames; /* long names that ignore cache */
133 };
134
135 struct psemname {
136 char *psem_nameptr; /* pointer to looked up name */
137 size_t psem_namelen; /* length of looked up component */
138 u_int32_t psem_hash; /* hash value of looked up name */
139 };
140
141 struct psemnode {
142 struct pseminfo *pinfo;
143 #if DIAGNOSTIC
144 unsigned int readcnt;
145 unsigned int writecnt;
146 #endif
147 };
148 #define PSEMNODE_NULL (struct psemnode *)0
149
150
151 #define PSEMHASH(pnp) \
152 (&psemhashtbl[(pnp)->psem_hash & psemhash])
153 LIST_HEAD(psemhashhead, psemcache) * psemhashtbl; /* Hash Table */
154 u_long psemhash; /* size of hash table - 1 */
155 long psemnument; /* number of cache entries allocated */
156 long posix_sem_max = 10000; /* tunable for max POSIX semaphores */
157 /* 10000 limits to ~1M of memory */
158 SYSCTL_NODE(_kern, KERN_POSIX, posix, CTLFLAG_RW | CTLFLAG_LOCKED, 0, "Posix");
159 SYSCTL_NODE(_kern_posix, OID_AUTO, sem, CTLFLAG_RW | CTLFLAG_LOCKED, 0, "Semaphores");
160 SYSCTL_LONG(_kern_posix_sem, OID_AUTO, max, CTLFLAG_RW | CTLFLAG_LOCKED, &posix_sem_max, "max");
161
162 struct psemstats psemstats; /* cache effectiveness statistics */
163
164 static int psem_access(struct pseminfo *pinfo, mode_t mode, kauth_cred_t cred);
165 static int psem_cache_search(struct pseminfo **,
166 struct psemname *, struct psemcache **);
167 static int psem_delete(struct pseminfo * pinfo);
168
169 static int psem_closefile(struct fileglob *fp, vfs_context_t ctx);
170 static int psem_unlink_internal(struct pseminfo *pinfo, struct psemcache *pcache);
171
172 static const struct fileops psemops = {
173 .fo_type = DTYPE_PSXSEM,
174 .fo_read = fo_no_read,
175 .fo_write = fo_no_write,
176 .fo_ioctl = fo_no_ioctl,
177 .fo_select = fo_no_select,
178 .fo_close = psem_closefile,
179 .fo_drain = fo_no_drain,
180 .fo_kqfilter = fo_no_kqfilter,
181 };
182
183 static LCK_GRP_DECLARE(psx_sem_subsys_lck_grp, "posix semaphores");
184 static LCK_MTX_DECLARE(psx_sem_subsys_mutex, &psx_sem_subsys_lck_grp);
185
186 #define PSEM_SUBSYS_LOCK() lck_mtx_lock(&psx_sem_subsys_mutex)
187 #define PSEM_SUBSYS_UNLOCK() lck_mtx_unlock(&psx_sem_subsys_mutex)
188 #define PSEM_SUBSYS_ASSERT_HELD() LCK_MTX_ASSERT(&psx_sem_subsys_mutex, LCK_MTX_ASSERT_OWNED)
189
190
191 static int psem_cache_add(struct pseminfo *psemp, struct psemname *pnp, struct psemcache *pcp);
192 static void psem_cache_delete(struct psemcache *pcp);
193 int psem_cache_purge_all(void);
194
195 /*
196 * Lookup an entry in the cache
197 *
198 *
199 * status of -1 is returned if matches
200 * If the lookup determines that the name does not exist
201 * (negative cacheing), a status of ENOENT is returned. If the lookup
202 * fails, a status of zero is returned.
203 */
204
205 static int
psem_cache_search(struct pseminfo ** psemp,struct psemname * pnp,struct psemcache ** pcache)206 psem_cache_search(struct pseminfo **psemp, struct psemname *pnp,
207 struct psemcache **pcache)
208 {
209 struct psemcache *pcp, *nnp;
210 struct psemhashhead *pcpp;
211
212 if (pnp->psem_namelen > PSEMNAMLEN) {
213 psemstats.longnames++;
214 return PSEMCACHE_NOTFOUND;
215 }
216
217 pcpp = PSEMHASH(pnp);
218 for (pcp = pcpp->lh_first; pcp != 0; pcp = nnp) {
219 nnp = pcp->psem_hash.le_next;
220 if (pcp->psem_nlen == pnp->psem_namelen &&
221 !bcmp(pcp->psem_name, pnp->psem_nameptr, pcp->psem_nlen)) {
222 break;
223 }
224 }
225
226 if (pcp == 0) {
227 psemstats.miss++;
228 return PSEMCACHE_NOTFOUND;
229 }
230
231 /* We found a "positive" match, return the vnode */
232 if (pcp->pseminfo) {
233 psemstats.goodhits++;
234 /* TOUCH(ncp); */
235 *psemp = pcp->pseminfo;
236 *pcache = pcp;
237 return PSEMCACHE_FOUND;
238 }
239
240 /*
241 * We found a "negative" match, ENOENT notifies client of this match.
242 * The nc_vpid field records whether this is a whiteout.
243 */
244 psemstats.neghits++;
245 return PSEMCACHE_NEGATIVE;
246 }
247
248 /*
249 * Add an entry to the cache.
250 */
251 static int
psem_cache_add(struct pseminfo * psemp,struct psemname * pnp,struct psemcache * pcp)252 psem_cache_add(struct pseminfo *psemp, struct psemname *pnp, struct psemcache *pcp)
253 {
254 struct psemhashhead *pcpp;
255 struct pseminfo *dpinfo;
256 struct psemcache *dpcp;
257
258 #if DIAGNOSTIC
259 if (pnp->psem_namelen > PSEMNAMLEN) {
260 panic("cache_enter: name too long");
261 }
262 #endif
263
264
265 /* if the entry has already been added by some one else return */
266 if (psem_cache_search(&dpinfo, pnp, &dpcp) == PSEMCACHE_FOUND) {
267 return EEXIST;
268 }
269 if (psemnument >= posix_sem_max) {
270 return ENOSPC;
271 }
272 psemnument++;
273 /*
274 * Fill in cache info, if vp is NULL this is a "negative" cache entry.
275 * For negative entries, we have to record whether it is a whiteout.
276 * the whiteout flag is stored in the nc_vpid field which is
277 * otherwise unused.
278 */
279 pcp->pseminfo = psemp;
280 pcp->psem_nlen = pnp->psem_namelen;
281 bcopy(pnp->psem_nameptr, pcp->psem_name, pcp->psem_nlen);
282 pcpp = PSEMHASH(pnp);
283 #if DIAGNOSTIC
284 {
285 struct psemcache *p;
286
287 for (p = pcpp->lh_first; p != 0; p = p->psem_hash.le_next) {
288 if (p == pcp) {
289 panic("psem:cache_enter duplicate");
290 }
291 }
292 }
293 #endif
294 LIST_INSERT_HEAD(pcpp, pcp, psem_hash);
295 return 0;
296 }
297
298 /*
299 * Name cache initialization, from vfs_init() when we are booting
300 */
301 void
psem_cache_init(void)302 psem_cache_init(void)
303 {
304 psemhashtbl = hashinit((int)(posix_sem_max / 2), M_SHM, &psemhash);
305 }
306
307 static void
psem_cache_delete(struct psemcache * pcp)308 psem_cache_delete(struct psemcache *pcp)
309 {
310 #if DIAGNOSTIC
311 if (pcp->psem_hash.le_prev == 0) {
312 panic("psem namecache purge le_prev");
313 }
314 if (pcp->psem_hash.le_next == pcp) {
315 panic("namecache purge le_next");
316 }
317 #endif /* DIAGNOSTIC */
318 LIST_REMOVE(pcp, psem_hash);
319 pcp->psem_hash.le_prev = NULL;
320 psemnument--;
321 }
322
323 /*
324 * Remove all cached psem entries. Open semaphores (with a positive refcount)
325 * will continue to exist, but their cache entries tying them to a particular
326 * name/path will be removed making all future lookups on the name fail.
327 */
328 int
psem_cache_purge_all(void)329 psem_cache_purge_all(void)
330 {
331 struct psemcache *pcp, *tmppcp;
332 struct psemhashhead *pcpp;
333 int error = 0;
334
335 if (kauth_cred_issuser(kauth_cred_get()) == 0) {
336 return EPERM;
337 }
338
339 PSEM_SUBSYS_LOCK();
340 for (pcpp = &psemhashtbl[psemhash]; pcpp >= psemhashtbl; pcpp--) {
341 LIST_FOREACH_SAFE(pcp, pcpp, psem_hash, tmppcp) {
342 assert(pcp->psem_nlen);
343 /*
344 * unconditionally unlink the cache entry
345 */
346 error = psem_unlink_internal(pcp->pseminfo, pcp);
347 if (error) {
348 goto out;
349 }
350 }
351 }
352 assert(psemnument == 0);
353
354 out:
355 PSEM_SUBSYS_UNLOCK();
356
357 if (error) {
358 printf("%s: Error %d removing all semaphores: %ld remain!\n",
359 __func__, error, psemnument);
360 }
361 return error;
362 }
363
364 /*
365 * In order to support unnamed POSIX semaphores, the named
366 * POSIX semaphores will have to move out of the per-process
367 * open filetable, and into a global table that is shared with
368 * unnamed POSIX semaphores, since unnamed POSIX semaphores
369 * are typically used by declaring instances in shared memory,
370 * and there's no other way to do this without changing the
371 * underlying type, which would introduce binary compatibility
372 * issues.
373 */
374 int
sem_open(proc_t p,struct sem_open_args * uap,user_addr_t * retval)375 sem_open(proc_t p, struct sem_open_args *uap, user_addr_t *retval)
376 {
377 size_t i;
378 int indx, error;
379 struct psemname nd;
380 struct pseminfo *pinfo;
381 struct fileproc *fp = NULL;
382 char *pnbuf = NULL;
383 struct pseminfo *new_pinfo = PSEMINFO_NULL;
384 struct psemnode *new_pnode = PSEMNODE_NULL;
385 struct psemcache *pcache = PSEMCACHE_NULL;
386 char * nameptr;
387 char * cp;
388 size_t pathlen, plen;
389 mode_t fmode;
390 mode_t cmode = (mode_t)uap->mode;
391 int value = uap->value;
392 int incache = 0;
393 struct psemcache *pcp = PSEMCACHE_NULL;
394 kern_return_t kret = KERN_INVALID_ADDRESS; /* default fail */
395
396 AUDIT_ARG(fflags, uap->oflag);
397 AUDIT_ARG(mode, (mode_t)uap->mode);
398 AUDIT_ARG(value32, uap->value);
399
400 pinfo = PSEMINFO_NULL;
401
402 /*
403 * Preallocate everything we might need up front to avoid taking
404 * and dropping the lock, opening us up to race conditions.
405 */
406 pnbuf = zalloc_flags(ZV_NAMEI, Z_WAITOK | Z_ZERO);
407
408 pathlen = MAXPATHLEN;
409 error = copyinstr(uap->name, pnbuf, MAXPATHLEN, &pathlen);
410 if (error) {
411 goto bad;
412 }
413 AUDIT_ARG(text, pnbuf);
414 if ((pathlen > PSEMNAMLEN)) {
415 error = ENAMETOOLONG;
416 goto bad;
417 }
418
419 #ifdef PSXSEM_NAME_RESTRICT
420 nameptr = pnbuf;
421 if (*nameptr == '/') {
422 while (*(nameptr++) == '/') {
423 plen--;
424 error = EINVAL;
425 goto bad;
426 }
427 } else {
428 error = EINVAL;
429 goto bad;
430 }
431 #endif /* PSXSEM_NAME_RESTRICT */
432
433 plen = pathlen;
434 nameptr = pnbuf;
435 nd.psem_nameptr = nameptr;
436 nd.psem_namelen = plen;
437 nd.psem_hash = 0;
438
439 for (cp = nameptr, i = 1; *cp != 0 && i <= plen; i++, cp++) {
440 nd.psem_hash += (unsigned char)*cp * i;
441 }
442
443 /*
444 * attempt to allocate a new fp; if unsuccessful, the fp will be
445 * left unmodified (NULL).
446 */
447 error = falloc(p, &fp, &indx, vfs_context_current());
448 if (error) {
449 goto bad;
450 }
451
452 /*
453 * We allocate a new entry if we are less than the maximum
454 * allowed and the one at the front of the LRU list is in use.
455 * Otherwise we use the one at the front of the LRU list.
456 */
457 pcp = kalloc_type(struct psemcache, Z_WAITOK | Z_ZERO | Z_NOFAIL);
458 new_pinfo = kalloc_type(struct pseminfo, Z_WAITOK | Z_ZERO | Z_NOFAIL);
459 #if CONFIG_MACF
460 mac_posixsem_label_init(new_pinfo);
461 #endif
462
463 /*
464 * Provisionally create the semaphore in the new_pinfo; we have to do
465 * this here to prevent locking later. We use the value of kret to
466 * signal success or failure, which is why we set its default value
467 * to KERN_INVALID_ADDRESS, above.
468 */
469
470 fmode = (mode_t)FFLAGS(uap->oflag);
471
472 if ((fmode & O_CREAT)) {
473 if ((value < 0) || (value > SEM_VALUE_MAX)) {
474 error = EINVAL;
475 goto bad;
476 }
477
478 kret = semaphore_create(kernel_task, &new_pinfo->psem_semobject, SYNC_POLICY_FIFO, value);
479
480 if (kret != KERN_SUCCESS) {
481 switch (kret) {
482 case KERN_RESOURCE_SHORTAGE:
483 error = ENOMEM;
484 break;
485 case KERN_PROTECTION_FAILURE:
486 error = EACCES;
487 break;
488 default:
489 error = EINVAL;
490 }
491 goto bad;
492 }
493 }
494
495 new_pnode = kalloc_type(struct psemnode, Z_WAITOK | Z_ZERO | Z_NOFAIL);
496
497 PSEM_SUBSYS_LOCK();
498 error = psem_cache_search(&pinfo, &nd, &pcache);
499
500 if (error == PSEMCACHE_NEGATIVE) {
501 error = EINVAL;
502 goto bad_locked;
503 }
504
505 if (error == PSEMCACHE_FOUND) {
506 incache = 1;
507 } else {
508 incache = 0;
509 }
510
511 cmode &= ALLPERMS;
512
513 if (((fmode & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL)) && incache) {
514 /* sem exists and opened O_EXCL */
515 #if notyet
516 if (pinfo->psem_flags & PSEM_INDELETE) {
517 }
518 #endif
519 AUDIT_ARG(posix_ipc_perm, pinfo->psem_uid,
520 pinfo->psem_gid, pinfo->psem_mode);
521 error = EEXIST;
522 goto bad_locked;
523 }
524 if (((fmode & (O_CREAT | O_EXCL)) == O_CREAT) && incache) {
525 /* As per POSIX, O_CREAT has no effect */
526 fmode &= ~O_CREAT;
527 }
528
529 if ((fmode & O_CREAT)) {
530 /* create a new one (commit the allocation) */
531 pinfo = new_pinfo;
532 pinfo->psem_flags = PSEM_DEFINED | PSEM_INCREATE;
533 pinfo->psem_usecount = 1;
534 pinfo->psem_mode = cmode;
535 pinfo->psem_uid = kauth_getuid();
536 pinfo->psem_gid = kauth_getgid();
537 bcopy(pnbuf, &pinfo->psem_name[0], PSEMNAMLEN);
538 pinfo->psem_name[PSEMNAMLEN] = 0;
539 pinfo->psem_flags &= ~PSEM_DEFINED;
540 pinfo->psem_flags |= PSEM_ALLOCATED;
541 pinfo->psem_creator_pid = proc_getpid(p);
542 pinfo->psem_creator_uniqueid = proc_uniqueid(p);
543
544 #if CONFIG_MACF
545 error = mac_posixsem_check_create(kauth_cred_get(), nameptr);
546 if (error) {
547 goto bad_locked;
548 }
549 mac_posixsem_label_associate(kauth_cred_get(), pinfo, nameptr);
550 #endif
551 } else {
552 /* semaphore should exist as it is without O_CREAT */
553 if (!incache) {
554 error = ENOENT;
555 goto bad_locked;
556 }
557 if (pinfo->psem_flags & PSEM_INDELETE) {
558 error = ENOENT;
559 goto bad_locked;
560 }
561 AUDIT_ARG(posix_ipc_perm, pinfo->psem_uid,
562 pinfo->psem_gid, pinfo->psem_mode);
563 #if CONFIG_MACF
564 error = mac_posixsem_check_open(kauth_cred_get(), pinfo);
565 if (error) {
566 goto bad_locked;
567 }
568 #endif
569 if ((error = psem_access(pinfo, fmode, kauth_cred_get()))) {
570 goto bad_locked;
571 }
572 }
573
574 if (!incache) {
575 /* if successful, this will consume the pcp */
576 if ((error = psem_cache_add(pinfo, &nd, pcp))) {
577 goto bad_locked;
578 }
579 }
580 pinfo->psem_flags &= ~PSEM_INCREATE;
581 pinfo->psem_usecount++;
582 new_pnode->pinfo = pinfo;
583 PSEM_SUBSYS_UNLOCK();
584
585 /*
586 * if incache, we did not use the new pcp or the new pcp or the
587 * new . and we must free them.
588 */
589 if (incache) {
590 kfree_type(struct psemcache, pcp);
591 pcp = PSEMCACHE_NULL;
592 if (new_pinfo != PSEMINFO_NULL) {
593 /* return value ignored - we can't _not_ do this */
594 (void)semaphore_destroy(kernel_task, new_pinfo->psem_semobject);
595 #if CONFIG_MACF
596 mac_posixsem_label_destroy(new_pinfo);
597 #endif
598 kfree_type(struct pseminfo, new_pinfo);
599 new_pinfo = PSEMINFO_NULL;
600 }
601 }
602
603 proc_fdlock(p);
604 fp->f_flag = fmode & FMASK;
605 fp->f_ops = &psemops;
606 fp_set_data(fp, new_pnode);
607 procfdtbl_releasefd(p, indx, NULL);
608 fp_drop(p, indx, fp, 1);
609 proc_fdunlock(p);
610
611 *retval = CAST_USER_ADDR_T(indx);
612 zfree(ZV_NAMEI, pnbuf);
613 return 0;
614
615 bad_locked:
616 PSEM_SUBSYS_UNLOCK();
617 bad:
618 kfree_type(struct psemcache, pcp);
619
620 kfree_type(struct psemnode, new_pnode);
621
622 if (fp != NULL) {
623 fp_free(p, indx, fp);
624 }
625
626 if (new_pinfo != PSEMINFO_NULL) {
627 /*
628 * kret signals whether or not we successfully created a
629 * Mach semaphore for this semaphore; if so, we need to
630 * destroy it here.
631 */
632 if (kret == KERN_SUCCESS) {
633 /* return value ignored - we can't _not_ do this */
634 (void)semaphore_destroy(kernel_task, new_pinfo->psem_semobject);
635 }
636 #if CONFIG_MACF
637 mac_posixsem_label_destroy(new_pinfo);
638 #endif
639 kfree_type(struct pseminfo, new_pinfo);
640 }
641
642 if (pnbuf != NULL) {
643 zfree(ZV_NAMEI, pnbuf);
644 }
645 return error;
646 }
647
648 /*
649 * XXX This code is repeated in several places
650 */
651 static int
psem_access(struct pseminfo * pinfo,mode_t mode,kauth_cred_t cred)652 psem_access(struct pseminfo *pinfo, mode_t mode, kauth_cred_t cred)
653 {
654 mode_t mode_req = ((mode & FREAD) ? S_IRUSR : 0) |
655 ((mode & FWRITE) ? S_IWUSR : 0);
656
657 /* Otherwise, user id 0 always gets access. */
658 if (!suser(cred, NULL)) {
659 return 0;
660 }
661
662 return posix_cred_access(cred, pinfo->psem_uid, pinfo->psem_gid, pinfo->psem_mode, mode_req);
663 }
664
665 static int
psem_unlink_internal(struct pseminfo * pinfo,struct psemcache * pcache)666 psem_unlink_internal(struct pseminfo *pinfo, struct psemcache *pcache)
667 {
668 PSEM_SUBSYS_ASSERT_HELD();
669
670 if (!pinfo || !pcache) {
671 return EINVAL;
672 }
673
674 if ((pinfo->psem_flags & (PSEM_DEFINED | PSEM_ALLOCATED)) == 0) {
675 return EINVAL;
676 }
677
678 if (pinfo->psem_flags & PSEM_INDELETE) {
679 return 0;
680 }
681
682 AUDIT_ARG(posix_ipc_perm, pinfo->psem_uid, pinfo->psem_gid,
683 pinfo->psem_mode);
684
685 pinfo->psem_flags |= PSEM_INDELETE;
686 pinfo->psem_usecount--;
687
688 if (!pinfo->psem_usecount) {
689 psem_delete(pinfo);
690 kfree_type(struct pseminfo, pinfo);
691 } else {
692 pinfo->psem_flags |= PSEM_REMOVED;
693 }
694
695 psem_cache_delete(pcache);
696 kfree_type(struct psemcache, pcache);
697 return 0;
698 }
699
700
701 int
sem_unlink(__unused proc_t p,struct sem_unlink_args * uap,__unused int32_t * retval)702 sem_unlink(__unused proc_t p, struct sem_unlink_args *uap, __unused int32_t *retval)
703 {
704 size_t i;
705 int error = 0;
706 struct psemname nd;
707 struct pseminfo *pinfo;
708 char * nameptr;
709 char * cp;
710 char * pnbuf;
711 size_t pathlen;
712 struct psemcache *pcache = PSEMCACHE_NULL;
713
714 pinfo = PSEMINFO_NULL;
715
716 pnbuf = zalloc(ZV_NAMEI);
717
718 pathlen = MAXPATHLEN;
719 error = copyinstr(uap->name, pnbuf, MAXPATHLEN, &pathlen);
720 if (error) {
721 goto bad;
722 }
723 AUDIT_ARG(text, pnbuf);
724 if (pathlen > PSEMNAMLEN) {
725 error = ENAMETOOLONG;
726 goto bad;
727 }
728
729 nameptr = pnbuf;
730
731 #ifdef PSXSEM_NAME_RESTRICT
732 if (*nameptr == '/') {
733 while (*(nameptr++) == '/') {
734 pathlen--;
735 error = EINVAL;
736 goto bad;
737 }
738 } else {
739 error = EINVAL;
740 goto bad;
741 }
742 #endif /* PSXSEM_NAME_RESTRICT */
743
744 nd.psem_nameptr = nameptr;
745 nd.psem_namelen = pathlen;
746 nd.psem_hash = 0;
747
748 for (cp = nameptr, i = 1; *cp != 0 && i <= pathlen; i++, cp++) {
749 nd.psem_hash += (unsigned char)*cp * i;
750 }
751
752 PSEM_SUBSYS_LOCK();
753 error = psem_cache_search(&pinfo, &nd, &pcache);
754
755 if (error != PSEMCACHE_FOUND) {
756 PSEM_SUBSYS_UNLOCK();
757 error = ENOENT;
758 goto bad;
759 }
760
761 #if CONFIG_MACF
762 error = mac_posixsem_check_unlink(kauth_cred_get(), pinfo, nameptr);
763 if (error) {
764 PSEM_SUBSYS_UNLOCK();
765 goto bad;
766 }
767 #endif
768 if ((error = psem_access(pinfo, pinfo->psem_mode, kauth_cred_get()))) {
769 PSEM_SUBSYS_UNLOCK();
770 goto bad;
771 }
772
773 error = psem_unlink_internal(pinfo, pcache);
774 PSEM_SUBSYS_UNLOCK();
775
776 bad:
777 zfree(ZV_NAMEI, pnbuf);
778 return error;
779 }
780
781 int
sem_close(proc_t p,struct sem_close_args * uap,__unused int32_t * retval)782 sem_close(proc_t p, struct sem_close_args *uap, __unused int32_t *retval)
783 {
784 int fd = CAST_DOWN_EXPLICIT(int, uap->sem);
785 struct fileproc *fp;
786
787 AUDIT_ARG(fd, fd); /* XXX This seems wrong; uap->sem is a pointer */
788
789 proc_fdlock(p);
790 if ((fp = fp_get_noref_locked(p, fd)) == NULL) {
791 proc_fdunlock(p);
792 return EBADF;
793 }
794 if (FILEGLOB_DTYPE(fp->fp_glob) != DTYPE_PSXSEM) {
795 proc_fdunlock(p);
796 return EBADF;
797 }
798 return fp_close_and_unlock(p, fd, fp, 0);
799 }
800
801 int
sem_wait(proc_t p,struct sem_wait_args * uap,int32_t * retval)802 sem_wait(proc_t p, struct sem_wait_args *uap, int32_t *retval)
803 {
804 __pthread_testcancel(1);
805 return sem_wait_nocancel(p, (struct sem_wait_nocancel_args *)uap, retval);
806 }
807
808 int
sem_wait_nocancel(proc_t p,struct sem_wait_nocancel_args * uap,__unused int32_t * retval)809 sem_wait_nocancel(proc_t p, struct sem_wait_nocancel_args *uap, __unused int32_t *retval)
810 {
811 int fd = CAST_DOWN_EXPLICIT(int, uap->sem);
812 struct fileproc *fp;
813 struct pseminfo * pinfo;
814 struct psemnode * pnode;
815 kern_return_t kret;
816 int error;
817
818 error = fp_get_ftype(p, fd, DTYPE_PSXSEM, EBADF, &fp);
819 if (error) {
820 return error;
821 }
822 pnode = (struct psemnode *)fp_get_data(fp);
823
824 PSEM_SUBSYS_LOCK();
825 if ((pinfo = pnode->pinfo) == PSEMINFO_NULL) {
826 PSEM_SUBSYS_UNLOCK();
827 error = EINVAL;
828 goto out;
829 }
830 if ((pinfo->psem_flags & (PSEM_DEFINED | PSEM_ALLOCATED))
831 != PSEM_ALLOCATED) {
832 PSEM_SUBSYS_UNLOCK();
833 error = EINVAL;
834 goto out;
835 }
836 #if CONFIG_MACF
837 error = mac_posixsem_check_wait(kauth_cred_get(), pinfo);
838 if (error) {
839 PSEM_SUBSYS_UNLOCK();
840 goto out;
841 }
842 #endif
843 PSEM_SUBSYS_UNLOCK();
844 kret = semaphore_wait(pinfo->psem_semobject);
845 switch (kret) {
846 case KERN_INVALID_ADDRESS:
847 case KERN_PROTECTION_FAILURE:
848 error = EACCES;
849 break;
850 case KERN_ABORTED:
851 case KERN_OPERATION_TIMED_OUT:
852 error = EINTR;
853 break;
854 case KERN_SUCCESS:
855 error = 0;
856 break;
857 default:
858 error = EINVAL;
859 break;
860 }
861 out:
862 fp_drop(p, fd, fp, 0);
863 return error;
864 }
865
866 int
sem_trywait(proc_t p,struct sem_trywait_args * uap,__unused int32_t * retval)867 sem_trywait(proc_t p, struct sem_trywait_args *uap, __unused int32_t *retval)
868 {
869 int fd = CAST_DOWN_EXPLICIT(int, uap->sem);
870 struct fileproc *fp;
871 struct pseminfo * pinfo;
872 struct psemnode * pnode;
873 kern_return_t kret;
874 mach_timespec_t wait_time;
875 int error;
876
877 error = fp_get_ftype(p, fd, DTYPE_PSXSEM, EBADF, &fp);
878 if (error) {
879 return error;
880 }
881 pnode = (struct psemnode *)fp_get_data(fp);
882
883 PSEM_SUBSYS_LOCK();
884 if ((pinfo = pnode->pinfo) == PSEMINFO_NULL) {
885 PSEM_SUBSYS_UNLOCK();
886 error = EINVAL;
887 goto out;
888 }
889 if ((pinfo->psem_flags & (PSEM_DEFINED | PSEM_ALLOCATED))
890 != PSEM_ALLOCATED) {
891 PSEM_SUBSYS_UNLOCK();
892 error = EINVAL;
893 goto out;
894 }
895 #if CONFIG_MACF
896 error = mac_posixsem_check_wait(kauth_cred_get(), pinfo);
897 if (error) {
898 PSEM_SUBSYS_UNLOCK();
899 goto out;
900 }
901 #endif
902 PSEM_SUBSYS_UNLOCK();
903 wait_time.tv_sec = 0;
904 wait_time.tv_nsec = 0;
905
906 kret = semaphore_timedwait(pinfo->psem_semobject, MACH_TIMESPEC_ZERO);
907 switch (kret) {
908 case KERN_INVALID_ADDRESS:
909 case KERN_PROTECTION_FAILURE:
910 error = EINVAL;
911 break;
912 case KERN_ABORTED:
913 error = EINTR;
914 break;
915 case KERN_OPERATION_TIMED_OUT:
916 error = EAGAIN;
917 break;
918 case KERN_SUCCESS:
919 error = 0;
920 break;
921 default:
922 error = EINVAL;
923 break;
924 }
925 out:
926 fp_drop(p, fd, fp, 0);
927 return error;
928 }
929
930 int
sem_post(proc_t p,struct sem_post_args * uap,__unused int32_t * retval)931 sem_post(proc_t p, struct sem_post_args *uap, __unused int32_t *retval)
932 {
933 int fd = CAST_DOWN_EXPLICIT(int, uap->sem);
934 struct fileproc *fp;
935 struct pseminfo * pinfo;
936 struct psemnode * pnode;
937 kern_return_t kret;
938 int error;
939
940 error = fp_get_ftype(p, fd, DTYPE_PSXSEM, EBADF, &fp);
941 if (error) {
942 return error;
943 }
944 pnode = (struct psemnode *)fp_get_data(fp);
945
946 PSEM_SUBSYS_LOCK();
947 if ((pinfo = pnode->pinfo) == PSEMINFO_NULL) {
948 PSEM_SUBSYS_UNLOCK();
949 error = EINVAL;
950 goto out;
951 }
952 if ((pinfo->psem_flags & (PSEM_DEFINED | PSEM_ALLOCATED))
953 != PSEM_ALLOCATED) {
954 PSEM_SUBSYS_UNLOCK();
955 error = EINVAL;
956 goto out;
957 }
958 #if CONFIG_MACF
959 error = mac_posixsem_check_post(kauth_cred_get(), pinfo);
960 if (error) {
961 PSEM_SUBSYS_UNLOCK();
962 goto out;
963 }
964 #endif
965 PSEM_SUBSYS_UNLOCK();
966 kret = semaphore_signal(pinfo->psem_semobject);
967 switch (kret) {
968 case KERN_INVALID_ADDRESS:
969 case KERN_PROTECTION_FAILURE:
970 error = EINVAL;
971 break;
972 case KERN_ABORTED:
973 case KERN_OPERATION_TIMED_OUT:
974 error = EINTR;
975 break;
976 case KERN_SUCCESS:
977 error = 0;
978 break;
979 default:
980 error = EINVAL;
981 break;
982 }
983 out:
984 fp_drop(p, fd, fp, 0);
985 return error;
986 }
987
988 static int
psem_close(struct psemnode * pnode)989 psem_close(struct psemnode *pnode)
990 {
991 int error = 0;
992 struct pseminfo *pinfo;
993
994 PSEM_SUBSYS_LOCK();
995 if ((pinfo = pnode->pinfo) == PSEMINFO_NULL) {
996 PSEM_SUBSYS_UNLOCK();
997 return EINVAL;
998 }
999
1000 if ((pinfo->psem_flags & PSEM_ALLOCATED) != PSEM_ALLOCATED) {
1001 PSEM_SUBSYS_UNLOCK();
1002 return EINVAL;
1003 }
1004 #if DIAGNOSTIC
1005 if (!pinfo->psem_usecount) {
1006 kprintf("negative usecount in psem_close\n");
1007 }
1008 #endif /* DIAGNOSTIC */
1009 pinfo->psem_usecount--;
1010
1011 if ((pinfo->psem_flags & PSEM_REMOVED) && !pinfo->psem_usecount) {
1012 PSEM_SUBSYS_UNLOCK();
1013 /* lock dropped as only semaphore is destroyed here */
1014 error = psem_delete(pinfo);
1015 kfree_type(struct pseminfo, pinfo);
1016 } else {
1017 PSEM_SUBSYS_UNLOCK();
1018 }
1019 /* subsystem lock is dropped when we get here */
1020 kfree_type(struct psemnode, pnode);
1021 return error;
1022 }
1023
1024 static int
psem_closefile(struct fileglob * fg,__unused vfs_context_t ctx)1025 psem_closefile(struct fileglob *fg, __unused vfs_context_t ctx)
1026 {
1027 /*
1028 * Not locked as psem_close is called only from here and is locked
1029 * properly
1030 */
1031 return psem_close((struct psemnode *)fg_get_data(fg));
1032 }
1033
1034 static int
psem_delete(struct pseminfo * pinfo)1035 psem_delete(struct pseminfo * pinfo)
1036 {
1037 kern_return_t kret;
1038
1039 kret = semaphore_destroy(kernel_task, pinfo->psem_semobject);
1040 #if CONFIG_MACF
1041 mac_posixsem_label_destroy(pinfo);
1042 #endif
1043
1044 switch (kret) {
1045 case KERN_INVALID_ADDRESS:
1046 case KERN_PROTECTION_FAILURE:
1047 return EINVAL;
1048 case KERN_ABORTED:
1049 case KERN_OPERATION_TIMED_OUT:
1050 return EINTR;
1051 case KERN_SUCCESS:
1052 return 0;
1053 default:
1054 return EINVAL;
1055 }
1056 }
1057
1058 int
fill_pseminfo(struct psemnode * pnode,struct psem_info * info)1059 fill_pseminfo(struct psemnode *pnode, struct psem_info * info)
1060 {
1061 struct pseminfo *pinfo;
1062 struct vinfo_stat *sb;
1063
1064 PSEM_SUBSYS_LOCK();
1065 if ((pinfo = pnode->pinfo) == PSEMINFO_NULL) {
1066 PSEM_SUBSYS_UNLOCK();
1067 return EINVAL;
1068 }
1069
1070 #if 0
1071 if ((pinfo->psem_flags & PSEM_ALLOCATED) != PSEM_ALLOCATED) {
1072 PSEM_SUBSYS_UNLOCK();
1073 return EINVAL;
1074 }
1075 #endif
1076
1077 sb = &info->psem_stat;
1078 bzero(sb, sizeof(struct vinfo_stat));
1079
1080 sb->vst_mode = pinfo->psem_mode;
1081 sb->vst_uid = pinfo->psem_uid;
1082 sb->vst_gid = pinfo->psem_gid;
1083 sb->vst_size = pinfo->psem_usecount;
1084 bcopy(&pinfo->psem_name[0], &info->psem_name[0], PSEMNAMLEN + 1);
1085
1086 PSEM_SUBSYS_UNLOCK();
1087 return 0;
1088 }
1089
1090 #if CONFIG_MACF
1091 void
psem_label_associate(struct fileproc * fp,struct vnode * vp,vfs_context_t ctx)1092 psem_label_associate(struct fileproc *fp, struct vnode *vp, vfs_context_t ctx)
1093 {
1094 struct psemnode *pnode;
1095 struct pseminfo *psem;
1096
1097 PSEM_SUBSYS_LOCK();
1098 pnode = (struct psemnode *)fp_get_data(fp);
1099 if (pnode != NULL) {
1100 psem = pnode->pinfo;
1101 if (psem != NULL) {
1102 mac_posixsem_vnode_label_associate(
1103 vfs_context_ucred(ctx), psem,
1104 mac_posixsem_label(psem),
1105 vp, mac_vnode_label(vp));
1106 }
1107 }
1108 PSEM_SUBSYS_UNLOCK();
1109 }
1110 #endif
1111