xref: /freebsd/sys/kern/subr_acl_posix1e.c (revision c6ec7d31830ab1c80edae95ad5e4b9dba10c47ac)
1 /*-
2  * Copyright (c) 1999-2006 Robert N. M. Watson
3  * All rights reserved.
4  *
5  * This software was developed by Robert Watson for the TrustedBSD Project.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 /*
29  * Developed by the TrustedBSD Project.
30  *
31  * ACL support routines specific to POSIX.1e access control lists.  These are
32  * utility routines for code common across file systems implementing POSIX.1e
33  * ACLs.
34  */
35 
36 #include <sys/cdefs.h>
37 __FBSDID("$FreeBSD$");
38 
39 #include <sys/param.h>
40 #include <sys/kernel.h>
41 #include <sys/module.h>
42 #include <sys/systm.h>
43 #include <sys/mount.h>
44 #include <sys/priv.h>
45 #include <sys/vnode.h>
46 #include <sys/errno.h>
47 #include <sys/stat.h>
48 #include <sys/acl.h>
49 
50 /*
51  * Implement a version of vaccess() that understands POSIX.1e ACL semantics;
52  * the access ACL has already been prepared for evaluation by the file system
53  * and is passed via 'uid', 'gid', and 'acl'.  Return 0 on success, else an
54  * errno value.
55  */
56 int
57 vaccess_acl_posix1e(enum vtype type, uid_t file_uid, gid_t file_gid,
58     struct acl *acl, accmode_t accmode, struct ucred *cred, int *privused)
59 {
60 	struct acl_entry *acl_other, *acl_mask;
61 	accmode_t dac_granted;
62 	accmode_t priv_granted;
63 	accmode_t acl_mask_granted;
64 	int group_matched, i;
65 
66 	KASSERT((accmode & ~(VEXEC | VWRITE | VREAD | VADMIN | VAPPEND)) == 0,
67 	    ("invalid bit in accmode"));
68 	KASSERT((accmode & VAPPEND) == 0 || (accmode & VWRITE),
69 	    	("VAPPEND without VWRITE"));
70 
71 	/*
72 	 * Look for a normal, non-privileged way to access the file/directory
73 	 * as requested.  If it exists, go with that.  Otherwise, attempt to
74 	 * use privileges granted via priv_granted.  In some cases, which
75 	 * privileges to use may be ambiguous due to "best match", in which
76 	 * case fall back on first match for the time being.
77 	 */
78 	if (privused != NULL)
79 		*privused = 0;
80 
81 	/*
82 	 * Determine privileges now, but don't apply until we've found a DAC
83 	 * entry that matches but has failed to allow access.
84 	 *
85 	 * XXXRW: Ideally, we'd determine the privileges required before
86 	 * asking for them.
87 	 */
88 	priv_granted = 0;
89 
90 	if (type == VDIR) {
91 		if ((accmode & VEXEC) && !priv_check_cred(cred,
92 		     PRIV_VFS_LOOKUP, 0))
93 			priv_granted |= VEXEC;
94 	} else {
95 		/*
96 		 * Ensure that at least one execute bit is on. Otherwise,
97 		 * a privileged user will always succeed, and we don't want
98 		 * this to happen unless the file really is executable.
99 		 */
100 		if ((accmode & VEXEC) && (acl_posix1e_acl_to_mode(acl) &
101 		    (S_IXUSR | S_IXGRP | S_IXOTH)) != 0 &&
102 		    !priv_check_cred(cred, PRIV_VFS_EXEC, 0))
103 			priv_granted |= VEXEC;
104 	}
105 
106 	if ((accmode & VREAD) && !priv_check_cred(cred, PRIV_VFS_READ, 0))
107 		priv_granted |= VREAD;
108 
109 	if (((accmode & VWRITE) || (accmode & VAPPEND)) &&
110 	    !priv_check_cred(cred, PRIV_VFS_WRITE, 0))
111 		priv_granted |= (VWRITE | VAPPEND);
112 
113 	if ((accmode & VADMIN) && !priv_check_cred(cred, PRIV_VFS_ADMIN, 0))
114 		priv_granted |= VADMIN;
115 
116 	/*
117 	 * The owner matches if the effective uid associated with the
118 	 * credential matches that of the ACL_USER_OBJ entry.  While we're
119 	 * doing the first scan, also cache the location of the ACL_MASK and
120 	 * ACL_OTHER entries, preventing some future iterations.
121 	 */
122 	acl_mask = acl_other = NULL;
123 	for (i = 0; i < acl->acl_cnt; i++) {
124 		switch (acl->acl_entry[i].ae_tag) {
125 		case ACL_USER_OBJ:
126 			if (file_uid != cred->cr_uid)
127 				break;
128 			dac_granted = 0;
129 			dac_granted |= VADMIN;
130 			if (acl->acl_entry[i].ae_perm & ACL_EXECUTE)
131 				dac_granted |= VEXEC;
132 			if (acl->acl_entry[i].ae_perm & ACL_READ)
133 				dac_granted |= VREAD;
134 			if (acl->acl_entry[i].ae_perm & ACL_WRITE)
135 				dac_granted |= (VWRITE | VAPPEND);
136 			if ((accmode & dac_granted) == accmode)
137 				return (0);
138 
139 			/*
140 			 * XXXRW: Do privilege lookup here.
141 			 */
142 			if ((accmode & (dac_granted | priv_granted)) ==
143 			    accmode) {
144 				if (privused != NULL)
145 					*privused = 1;
146 				return (0);
147 			}
148 			goto error;
149 
150 		case ACL_MASK:
151 			acl_mask = &acl->acl_entry[i];
152 			break;
153 
154 		case ACL_OTHER:
155 			acl_other = &acl->acl_entry[i];
156 			break;
157 
158 		default:
159 			break;
160 		}
161 	}
162 
163 	/*
164 	 * An ACL_OTHER entry should always exist in a valid access ACL.  If
165 	 * it doesn't, then generate a serious failure.  For now, this means
166 	 * a debugging message and EPERM, but in the future should probably
167 	 * be a panic.
168 	 */
169 	if (acl_other == NULL) {
170 		/*
171 		 * XXX This should never happen
172 		 */
173 		printf("vaccess_acl_posix1e: ACL_OTHER missing\n");
174 		return (EPERM);
175 	}
176 
177 	/*
178 	 * Checks against ACL_USER, ACL_GROUP_OBJ, and ACL_GROUP fields are
179 	 * masked by an ACL_MASK entry, if any.  As such, first identify the
180 	 * ACL_MASK field, then iterate through identifying potential user
181 	 * matches, then group matches.  If there is no ACL_MASK, assume that
182 	 * the mask allows all requests to succeed.
183 	 */
184 	if (acl_mask != NULL) {
185 		acl_mask_granted = 0;
186 		if (acl_mask->ae_perm & ACL_EXECUTE)
187 			acl_mask_granted |= VEXEC;
188 		if (acl_mask->ae_perm & ACL_READ)
189 			acl_mask_granted |= VREAD;
190 		if (acl_mask->ae_perm & ACL_WRITE)
191 			acl_mask_granted |= (VWRITE | VAPPEND);
192 	} else
193 		acl_mask_granted = VEXEC | VREAD | VWRITE | VAPPEND;
194 
195 	/*
196 	 * Check ACL_USER ACL entries.  There will either be one or no
197 	 * matches; if there is one, we accept or rejected based on the
198 	 * match; otherwise, we continue on to groups.
199 	 */
200 	for (i = 0; i < acl->acl_cnt; i++) {
201 		switch (acl->acl_entry[i].ae_tag) {
202 		case ACL_USER:
203 			if (acl->acl_entry[i].ae_id != cred->cr_uid)
204 				break;
205 			dac_granted = 0;
206 			if (acl->acl_entry[i].ae_perm & ACL_EXECUTE)
207 				dac_granted |= VEXEC;
208 			if (acl->acl_entry[i].ae_perm & ACL_READ)
209 				dac_granted |= VREAD;
210 			if (acl->acl_entry[i].ae_perm & ACL_WRITE)
211 				dac_granted |= (VWRITE | VAPPEND);
212 			dac_granted &= acl_mask_granted;
213 			if ((accmode & dac_granted) == accmode)
214 				return (0);
215 			/*
216 			 * XXXRW: Do privilege lookup here.
217 			 */
218 			if ((accmode & (dac_granted | priv_granted)) !=
219 			    accmode)
220 				goto error;
221 
222 			if (privused != NULL)
223 				*privused = 1;
224 			return (0);
225 		}
226 	}
227 
228 	/*
229 	 * Group match is best-match, not first-match, so find a "best"
230 	 * match.  Iterate across, testing each potential group match.  Make
231 	 * sure we keep track of whether we found a match or not, so that we
232 	 * know if we should try again with any available privilege, or if we
233 	 * should move on to ACL_OTHER.
234 	 */
235 	group_matched = 0;
236 	for (i = 0; i < acl->acl_cnt; i++) {
237 		switch (acl->acl_entry[i].ae_tag) {
238 		case ACL_GROUP_OBJ:
239 			if (!groupmember(file_gid, cred))
240 				break;
241 			dac_granted = 0;
242 			if (acl->acl_entry[i].ae_perm & ACL_EXECUTE)
243 				dac_granted |= VEXEC;
244 			if (acl->acl_entry[i].ae_perm & ACL_READ)
245 				dac_granted |= VREAD;
246 			if (acl->acl_entry[i].ae_perm & ACL_WRITE)
247 				dac_granted |= (VWRITE | VAPPEND);
248 			dac_granted  &= acl_mask_granted;
249 
250 			if ((accmode & dac_granted) == accmode)
251 				return (0);
252 
253 			group_matched = 1;
254 			break;
255 
256 		case ACL_GROUP:
257 			if (!groupmember(acl->acl_entry[i].ae_id, cred))
258 				break;
259 			dac_granted = 0;
260 			if (acl->acl_entry[i].ae_perm & ACL_EXECUTE)
261 				dac_granted |= VEXEC;
262 			if (acl->acl_entry[i].ae_perm & ACL_READ)
263 				dac_granted |= VREAD;
264 			if (acl->acl_entry[i].ae_perm & ACL_WRITE)
265 				dac_granted |= (VWRITE | VAPPEND);
266 			dac_granted  &= acl_mask_granted;
267 
268 			if ((accmode & dac_granted) == accmode)
269 				return (0);
270 
271 			group_matched = 1;
272 			break;
273 
274 		default:
275 			break;
276 		}
277 	}
278 
279 	if (group_matched == 1) {
280 		/*
281 		 * There was a match, but it did not grant rights via pure
282 		 * DAC.  Try again, this time with privilege.
283 		 */
284 		for (i = 0; i < acl->acl_cnt; i++) {
285 			switch (acl->acl_entry[i].ae_tag) {
286 			case ACL_GROUP_OBJ:
287 				if (!groupmember(file_gid, cred))
288 					break;
289 				dac_granted = 0;
290 				if (acl->acl_entry[i].ae_perm & ACL_EXECUTE)
291 					dac_granted |= VEXEC;
292 				if (acl->acl_entry[i].ae_perm & ACL_READ)
293 					dac_granted |= VREAD;
294 				if (acl->acl_entry[i].ae_perm & ACL_WRITE)
295 					dac_granted |= (VWRITE | VAPPEND);
296 				dac_granted &= acl_mask_granted;
297 
298 				/*
299 				 * XXXRW: Do privilege lookup here.
300 				 */
301 				if ((accmode & (dac_granted | priv_granted))
302 				    != accmode)
303 					break;
304 
305 				if (privused != NULL)
306 					*privused = 1;
307 				return (0);
308 
309 			case ACL_GROUP:
310 				if (!groupmember(acl->acl_entry[i].ae_id,
311 				    cred))
312 					break;
313 				dac_granted = 0;
314 				if (acl->acl_entry[i].ae_perm & ACL_EXECUTE)
315 				dac_granted |= VEXEC;
316 				if (acl->acl_entry[i].ae_perm & ACL_READ)
317 					dac_granted |= VREAD;
318 				if (acl->acl_entry[i].ae_perm & ACL_WRITE)
319 					dac_granted |= (VWRITE | VAPPEND);
320 				dac_granted &= acl_mask_granted;
321 
322 				/*
323 				 * XXXRW: Do privilege lookup here.
324 				 */
325 				if ((accmode & (dac_granted | priv_granted))
326 				    != accmode)
327 					break;
328 
329 				if (privused != NULL)
330 					*privused = 1;
331 				return (0);
332 
333 			default:
334 				break;
335 			}
336 		}
337 		/*
338 		 * Even with privilege, group membership was not sufficient.
339 		 * Return failure.
340 		 */
341 		goto error;
342 	}
343 
344 	/*
345 	 * Fall back on ACL_OTHER.  ACL_MASK is not applied to ACL_OTHER.
346 	 */
347 	dac_granted = 0;
348 	if (acl_other->ae_perm & ACL_EXECUTE)
349 		dac_granted |= VEXEC;
350 	if (acl_other->ae_perm & ACL_READ)
351 		dac_granted |= VREAD;
352 	if (acl_other->ae_perm & ACL_WRITE)
353 		dac_granted |= (VWRITE | VAPPEND);
354 
355 	if ((accmode & dac_granted) == accmode)
356 		return (0);
357 	/*
358 	 * XXXRW: Do privilege lookup here.
359 	 */
360 	if ((accmode & (dac_granted | priv_granted)) == accmode) {
361 		if (privused != NULL)
362 			*privused = 1;
363 		return (0);
364 	}
365 
366 error:
367 	return ((accmode & VADMIN) ? EPERM : EACCES);
368 }
369 
370 /*
371  * For the purposes of filesystems maintaining the _OBJ entries in an inode
372  * with a mode_t field, this routine converts a mode_t entry to an
373  * acl_perm_t.
374  */
375 acl_perm_t
376 acl_posix1e_mode_to_perm(acl_tag_t tag, mode_t mode)
377 {
378 	acl_perm_t	perm = 0;
379 
380 	switch(tag) {
381 	case ACL_USER_OBJ:
382 		if (mode & S_IXUSR)
383 			perm |= ACL_EXECUTE;
384 		if (mode & S_IRUSR)
385 			perm |= ACL_READ;
386 		if (mode & S_IWUSR)
387 			perm |= ACL_WRITE;
388 		return (perm);
389 
390 	case ACL_GROUP_OBJ:
391 		if (mode & S_IXGRP)
392 			perm |= ACL_EXECUTE;
393 		if (mode & S_IRGRP)
394 			perm |= ACL_READ;
395 		if (mode & S_IWGRP)
396 			perm |= ACL_WRITE;
397 		return (perm);
398 
399 	case ACL_OTHER:
400 		if (mode & S_IXOTH)
401 			perm |= ACL_EXECUTE;
402 		if (mode & S_IROTH)
403 			perm |= ACL_READ;
404 		if (mode & S_IWOTH)
405 			perm |= ACL_WRITE;
406 		return (perm);
407 
408 	default:
409 		printf("acl_posix1e_mode_to_perm: invalid tag (%d)\n", tag);
410 		return (0);
411 	}
412 }
413 
414 /*
415  * Given inode information (uid, gid, mode), return an acl entry of the
416  * appropriate type.
417  */
418 struct acl_entry
419 acl_posix1e_mode_to_entry(acl_tag_t tag, uid_t uid, gid_t gid, mode_t mode)
420 {
421 	struct acl_entry	acl_entry;
422 
423 	acl_entry.ae_tag = tag;
424 	acl_entry.ae_perm = acl_posix1e_mode_to_perm(tag, mode);
425 	acl_entry.ae_entry_type = 0;
426 	acl_entry.ae_flags = 0;
427 	switch(tag) {
428 	case ACL_USER_OBJ:
429 		acl_entry.ae_id = uid;
430 		break;
431 
432 	case ACL_GROUP_OBJ:
433 		acl_entry.ae_id = gid;
434 		break;
435 
436 	case ACL_OTHER:
437 		acl_entry.ae_id = ACL_UNDEFINED_ID;
438 		break;
439 
440 	default:
441 		acl_entry.ae_id = ACL_UNDEFINED_ID;
442 		printf("acl_posix1e_mode_to_entry: invalid tag (%d)\n", tag);
443 	}
444 
445 	return (acl_entry);
446 }
447 
448 /*
449  * Utility function to generate a file mode given appropriate ACL entries.
450  */
451 mode_t
452 acl_posix1e_perms_to_mode(struct acl_entry *acl_user_obj_entry,
453     struct acl_entry *acl_group_obj_entry, struct acl_entry *acl_other_entry)
454 {
455 	mode_t	mode;
456 
457 	mode = 0;
458 	if (acl_user_obj_entry->ae_perm & ACL_EXECUTE)
459 		mode |= S_IXUSR;
460 	if (acl_user_obj_entry->ae_perm & ACL_READ)
461 		mode |= S_IRUSR;
462 	if (acl_user_obj_entry->ae_perm & ACL_WRITE)
463 		mode |= S_IWUSR;
464 	if (acl_group_obj_entry->ae_perm & ACL_EXECUTE)
465 		mode |= S_IXGRP;
466 	if (acl_group_obj_entry->ae_perm & ACL_READ)
467 		mode |= S_IRGRP;
468 	if (acl_group_obj_entry->ae_perm & ACL_WRITE)
469 		mode |= S_IWGRP;
470 	if (acl_other_entry->ae_perm & ACL_EXECUTE)
471 		mode |= S_IXOTH;
472 	if (acl_other_entry->ae_perm & ACL_READ)
473 		mode |= S_IROTH;
474 	if (acl_other_entry->ae_perm & ACL_WRITE)
475 		mode |= S_IWOTH;
476 
477 	return (mode);
478 }
479 
480 /*
481  * Utility function to generate a file mode given a complete POSIX.1e access
482  * ACL.  Note that if the ACL is improperly formed, this may result in a
483  * panic.
484  */
485 mode_t
486 acl_posix1e_acl_to_mode(struct acl *acl)
487 {
488 	struct acl_entry *acl_mask, *acl_user_obj, *acl_group_obj, *acl_other;
489 	int i;
490 
491 	/*
492 	 * Find the ACL entries relevant to a POSIX permission mode.
493 	 */
494 	acl_user_obj = acl_group_obj = acl_other = acl_mask = NULL;
495 	for (i = 0; i < acl->acl_cnt; i++) {
496 		switch (acl->acl_entry[i].ae_tag) {
497 		case ACL_USER_OBJ:
498 			acl_user_obj = &acl->acl_entry[i];
499 			break;
500 
501 		case ACL_GROUP_OBJ:
502 			acl_group_obj = &acl->acl_entry[i];
503 			break;
504 
505 		case ACL_OTHER:
506 			acl_other = &acl->acl_entry[i];
507 			break;
508 
509 		case ACL_MASK:
510 			acl_mask = &acl->acl_entry[i];
511 			break;
512 
513 		case ACL_USER:
514 		case ACL_GROUP:
515 			break;
516 
517 		default:
518 			panic("acl_posix1e_acl_to_mode: bad ae_tag");
519 		}
520 	}
521 
522 	if (acl_user_obj == NULL || acl_group_obj == NULL || acl_other == NULL)
523 		panic("acl_posix1e_acl_to_mode: missing base ae_tags");
524 
525 	/*
526 	 * POSIX.1e specifies that if there is an ACL_MASK entry, we replace
527 	 * the mode "group" bits with its permissions.  If there isn't, we
528 	 * use the ACL_GROUP_OBJ permissions.
529 	 */
530 	if (acl_mask != NULL)
531 		return (acl_posix1e_perms_to_mode(acl_user_obj, acl_mask,
532 		    acl_other));
533 	else
534 		return (acl_posix1e_perms_to_mode(acl_user_obj, acl_group_obj,
535 		    acl_other));
536 }
537 
538 /*
539  * Perform a syntactic check of the ACL, sufficient to allow an implementing
540  * filesystem to determine if it should accept this and rely on the POSIX.1e
541  * ACL properties.
542  */
543 int
544 acl_posix1e_check(struct acl *acl)
545 {
546 	int num_acl_user_obj, num_acl_user, num_acl_group_obj, num_acl_group;
547 	int num_acl_mask, num_acl_other, i;
548 
549 	/*
550 	 * Verify that the number of entries does not exceed the maximum
551 	 * defined for acl_t.
552 	 *
553 	 * Verify that the correct number of various sorts of ae_tags are
554 	 * present:
555 	 *   Exactly one ACL_USER_OBJ
556 	 *   Exactly one ACL_GROUP_OBJ
557 	 *   Exactly one ACL_OTHER
558 	 *   If any ACL_USER or ACL_GROUP entries appear, then exactly one
559 	 *   ACL_MASK entry must also appear.
560 	 *
561 	 * Verify that all ae_perm entries are in ACL_PERM_BITS.
562 	 *
563 	 * Verify all ae_tag entries are understood by this implementation.
564 	 *
565 	 * Note: Does not check for uniqueness of qualifier (ae_id) field.
566 	 */
567 	num_acl_user_obj = num_acl_user = num_acl_group_obj = num_acl_group =
568 	    num_acl_mask = num_acl_other = 0;
569 	if (acl->acl_cnt > ACL_MAX_ENTRIES)
570 		return (EINVAL);
571 	for (i = 0; i < acl->acl_cnt; i++) {
572 		/*
573 		 * Check for a valid tag.
574 		 */
575 		switch(acl->acl_entry[i].ae_tag) {
576 		case ACL_USER_OBJ:
577 			acl->acl_entry[i].ae_id = ACL_UNDEFINED_ID; /* XXX */
578 			if (acl->acl_entry[i].ae_id != ACL_UNDEFINED_ID)
579 				return (EINVAL);
580 			num_acl_user_obj++;
581 			break;
582 		case ACL_GROUP_OBJ:
583 			acl->acl_entry[i].ae_id = ACL_UNDEFINED_ID; /* XXX */
584 			if (acl->acl_entry[i].ae_id != ACL_UNDEFINED_ID)
585 				return (EINVAL);
586 			num_acl_group_obj++;
587 			break;
588 		case ACL_USER:
589 			if (acl->acl_entry[i].ae_id == ACL_UNDEFINED_ID)
590 				return (EINVAL);
591 			num_acl_user++;
592 			break;
593 		case ACL_GROUP:
594 			if (acl->acl_entry[i].ae_id == ACL_UNDEFINED_ID)
595 				return (EINVAL);
596 			num_acl_group++;
597 			break;
598 		case ACL_OTHER:
599 			acl->acl_entry[i].ae_id = ACL_UNDEFINED_ID; /* XXX */
600 			if (acl->acl_entry[i].ae_id != ACL_UNDEFINED_ID)
601 				return (EINVAL);
602 			num_acl_other++;
603 			break;
604 		case ACL_MASK:
605 			acl->acl_entry[i].ae_id = ACL_UNDEFINED_ID; /* XXX */
606 			if (acl->acl_entry[i].ae_id != ACL_UNDEFINED_ID)
607 				return (EINVAL);
608 			num_acl_mask++;
609 			break;
610 		default:
611 			return (EINVAL);
612 		}
613 		/*
614 		 * Check for valid perm entries.
615 		 */
616 		if ((acl->acl_entry[i].ae_perm | ACL_PERM_BITS) !=
617 		    ACL_PERM_BITS)
618 			return (EINVAL);
619 	}
620 	if ((num_acl_user_obj != 1) || (num_acl_group_obj != 1) ||
621 	    (num_acl_other != 1) || (num_acl_mask != 0 && num_acl_mask != 1))
622 		return (EINVAL);
623 	if (((num_acl_group != 0) || (num_acl_user != 0)) &&
624 	    (num_acl_mask != 1))
625 		return (EINVAL);
626 	return (0);
627 }
628 
629 /*
630  * Given a requested mode for a new object, and a default ACL, combine the
631  * two to produce a new mode.  Be careful not to clear any bits that aren't
632  * intended to be affected by the POSIX.1e ACL.  Eventually, this might also
633  * take the cmask as an argument, if we push that down into
634  * per-filesystem-code.
635  */
636 mode_t
637 acl_posix1e_newfilemode(mode_t cmode, struct acl *dacl)
638 {
639 	mode_t mode;
640 
641 	mode = cmode;
642 	/*
643 	 * The current composition policy is that a permission bit must be
644 	 * set in *both* the ACL and the requested creation mode for it to
645 	 * appear in the resulting mode/ACL.  First clear any possibly
646 	 * effected bits, then reconstruct.
647 	 */
648 	mode &= ACL_PRESERVE_MASK;
649 	mode |= (ACL_OVERRIDE_MASK & cmode & acl_posix1e_acl_to_mode(dacl));
650 
651 	return (mode);
652 }
653 
654 
655 static int
656 acl_posix1e_modload(module_t mod, int what, void *arg)
657 {
658 	int ret;
659 
660 	ret = 0;
661 
662 	switch (what) {
663 	case MOD_LOAD:
664 	case MOD_SHUTDOWN:
665 		break;
666 
667 	case MOD_QUIESCE:
668 		/* XXX TODO */
669 		ret = 0;
670 		break;
671 
672 	case MOD_UNLOAD:
673 		/* XXX TODO */
674 		ret = 0;
675 		break;
676 	default:
677 		ret = EINVAL;
678 		break;
679 	}
680 
681 	return (ret);
682 }
683 
684 static moduledata_t acl_posix1e_mod = {
685 	"acl_posix1e",
686 	acl_posix1e_modload,
687 	NULL
688 };
689 
690 DECLARE_MODULE(acl_posix1e, acl_posix1e_mod, SI_SUB_VFS, SI_ORDER_FIRST);
691 MODULE_VERSION(acl_posix1e, 1);
692