xref: /freebsd/sys/kern/subr_acl_posix1e.c (revision af23369a6deaaeb612ab266eb88b8bb8d560c322)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3  *
4  * Copyright (c) 1999-2006 Robert N. M. Watson
5  * All rights reserved.
6  *
7  * This software was developed by Robert Watson for the TrustedBSD Project.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28  * SUCH DAMAGE.
29  */
30 /*
31  * Developed by the TrustedBSD Project.
32  *
33  * ACL support routines specific to POSIX.1e access control lists.  These are
34  * utility routines for code common across file systems implementing POSIX.1e
35  * ACLs.
36  */
37 
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
40 
41 #include <sys/param.h>
42 #include <sys/kernel.h>
43 #include <sys/module.h>
44 #include <sys/systm.h>
45 #include <sys/mount.h>
46 #include <sys/priv.h>
47 #include <sys/vnode.h>
48 #include <sys/errno.h>
49 #include <sys/stat.h>
50 #include <sys/acl.h>
51 
52 /*
53  * Implement a version of vaccess() that understands POSIX.1e ACL semantics;
54  * the access ACL has already been prepared for evaluation by the file system
55  * and is passed via 'uid', 'gid', and 'acl'.  Return 0 on success, else an
56  * errno value.
57  */
58 int
59 vaccess_acl_posix1e(enum vtype type, uid_t file_uid, gid_t file_gid,
60     struct acl *acl, accmode_t accmode, struct ucred *cred)
61 {
62 	struct acl_entry *acl_other, *acl_mask;
63 	accmode_t dac_granted;
64 	accmode_t priv_granted;
65 	accmode_t acl_mask_granted;
66 	int group_matched, i;
67 
68 	KASSERT((accmode & ~(VEXEC | VWRITE | VREAD | VADMIN | VAPPEND)) == 0,
69 	    ("invalid bit in accmode"));
70 	KASSERT((accmode & VAPPEND) == 0 || (accmode & VWRITE),
71 	    	("VAPPEND without VWRITE"));
72 
73 	/*
74 	 * Look for a normal, non-privileged way to access the file/directory
75 	 * as requested.  If it exists, go with that.  Otherwise, attempt to
76 	 * use privileges granted via priv_granted.  In some cases, which
77 	 * privileges to use may be ambiguous due to "best match", in which
78 	 * case fall back on first match for the time being.
79 	 */
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, PRIV_VFS_LOOKUP))
92 			priv_granted |= VEXEC;
93 	} else {
94 		/*
95 		 * Ensure that at least one execute bit is on. Otherwise,
96 		 * a privileged user will always succeed, and we don't want
97 		 * this to happen unless the file really is executable.
98 		 */
99 		if ((accmode & VEXEC) && (acl_posix1e_acl_to_mode(acl) &
100 		    (S_IXUSR | S_IXGRP | S_IXOTH)) != 0 &&
101 		    !priv_check_cred(cred, PRIV_VFS_EXEC))
102 			priv_granted |= VEXEC;
103 	}
104 
105 	if ((accmode & VREAD) && !priv_check_cred(cred, PRIV_VFS_READ))
106 		priv_granted |= VREAD;
107 
108 	if (((accmode & VWRITE) || (accmode & VAPPEND)) &&
109 	    !priv_check_cred(cred, PRIV_VFS_WRITE))
110 		priv_granted |= (VWRITE | VAPPEND);
111 
112 	if ((accmode & VADMIN) && !priv_check_cred(cred, PRIV_VFS_ADMIN))
113 		priv_granted |= VADMIN;
114 
115 	/*
116 	 * The owner matches if the effective uid associated with the
117 	 * credential matches that of the ACL_USER_OBJ entry.  While we're
118 	 * doing the first scan, also cache the location of the ACL_MASK and
119 	 * ACL_OTHER entries, preventing some future iterations.
120 	 */
121 	acl_mask = acl_other = NULL;
122 	for (i = 0; i < acl->acl_cnt; i++) {
123 		switch (acl->acl_entry[i].ae_tag) {
124 		case ACL_USER_OBJ:
125 			if (file_uid != cred->cr_uid)
126 				break;
127 			dac_granted = 0;
128 			dac_granted |= VADMIN;
129 			if (acl->acl_entry[i].ae_perm & ACL_EXECUTE)
130 				dac_granted |= VEXEC;
131 			if (acl->acl_entry[i].ae_perm & ACL_READ)
132 				dac_granted |= VREAD;
133 			if (acl->acl_entry[i].ae_perm & ACL_WRITE)
134 				dac_granted |= (VWRITE | VAPPEND);
135 			if ((accmode & dac_granted) == accmode)
136 				return (0);
137 
138 			/*
139 			 * XXXRW: Do privilege lookup here.
140 			 */
141 			if ((accmode & (dac_granted | priv_granted)) ==
142 			    accmode) {
143 				return (0);
144 			}
145 			goto error;
146 
147 		case ACL_MASK:
148 			acl_mask = &acl->acl_entry[i];
149 			break;
150 
151 		case ACL_OTHER:
152 			acl_other = &acl->acl_entry[i];
153 			break;
154 
155 		default:
156 			break;
157 		}
158 	}
159 
160 	/*
161 	 * An ACL_OTHER entry should always exist in a valid access ACL.  If
162 	 * it doesn't, then generate a serious failure.  For now, this means
163 	 * a debugging message and EPERM, but in the future should probably
164 	 * be a panic.
165 	 */
166 	if (acl_other == NULL) {
167 		/*
168 		 * XXX This should never happen
169 		 */
170 		printf("vaccess_acl_posix1e: ACL_OTHER missing\n");
171 		return (EPERM);
172 	}
173 
174 	/*
175 	 * Checks against ACL_USER, ACL_GROUP_OBJ, and ACL_GROUP fields are
176 	 * masked by an ACL_MASK entry, if any.  As such, first identify the
177 	 * ACL_MASK field, then iterate through identifying potential user
178 	 * matches, then group matches.  If there is no ACL_MASK, assume that
179 	 * the mask allows all requests to succeed.
180 	 */
181 	if (acl_mask != NULL) {
182 		acl_mask_granted = 0;
183 		if (acl_mask->ae_perm & ACL_EXECUTE)
184 			acl_mask_granted |= VEXEC;
185 		if (acl_mask->ae_perm & ACL_READ)
186 			acl_mask_granted |= VREAD;
187 		if (acl_mask->ae_perm & ACL_WRITE)
188 			acl_mask_granted |= (VWRITE | VAPPEND);
189 	} else
190 		acl_mask_granted = VEXEC | VREAD | VWRITE | VAPPEND;
191 
192 	/*
193 	 * Check ACL_USER ACL entries.  There will either be one or no
194 	 * matches; if there is one, we accept or rejected based on the
195 	 * match; otherwise, we continue on to groups.
196 	 */
197 	for (i = 0; i < acl->acl_cnt; i++) {
198 		switch (acl->acl_entry[i].ae_tag) {
199 		case ACL_USER:
200 			if (acl->acl_entry[i].ae_id != cred->cr_uid)
201 				break;
202 			dac_granted = 0;
203 			if (acl->acl_entry[i].ae_perm & ACL_EXECUTE)
204 				dac_granted |= VEXEC;
205 			if (acl->acl_entry[i].ae_perm & ACL_READ)
206 				dac_granted |= VREAD;
207 			if (acl->acl_entry[i].ae_perm & ACL_WRITE)
208 				dac_granted |= (VWRITE | VAPPEND);
209 			dac_granted &= acl_mask_granted;
210 			if ((accmode & dac_granted) == accmode)
211 				return (0);
212 			/*
213 			 * XXXRW: Do privilege lookup here.
214 			 */
215 			if ((accmode & (dac_granted | priv_granted)) !=
216 			    accmode)
217 				goto error;
218 
219 			return (0);
220 		}
221 	}
222 
223 	/*
224 	 * Group match is best-match, not first-match, so find a "best"
225 	 * match.  Iterate across, testing each potential group match.  Make
226 	 * sure we keep track of whether we found a match or not, so that we
227 	 * know if we should try again with any available privilege, or if we
228 	 * should move on to ACL_OTHER.
229 	 */
230 	group_matched = 0;
231 	for (i = 0; i < acl->acl_cnt; i++) {
232 		switch (acl->acl_entry[i].ae_tag) {
233 		case ACL_GROUP_OBJ:
234 			if (!groupmember(file_gid, cred))
235 				break;
236 			dac_granted = 0;
237 			if (acl->acl_entry[i].ae_perm & ACL_EXECUTE)
238 				dac_granted |= VEXEC;
239 			if (acl->acl_entry[i].ae_perm & ACL_READ)
240 				dac_granted |= VREAD;
241 			if (acl->acl_entry[i].ae_perm & ACL_WRITE)
242 				dac_granted |= (VWRITE | VAPPEND);
243 			dac_granted  &= acl_mask_granted;
244 
245 			if ((accmode & dac_granted) == accmode)
246 				return (0);
247 
248 			group_matched = 1;
249 			break;
250 
251 		case ACL_GROUP:
252 			if (!groupmember(acl->acl_entry[i].ae_id, cred))
253 				break;
254 			dac_granted = 0;
255 			if (acl->acl_entry[i].ae_perm & ACL_EXECUTE)
256 				dac_granted |= VEXEC;
257 			if (acl->acl_entry[i].ae_perm & ACL_READ)
258 				dac_granted |= VREAD;
259 			if (acl->acl_entry[i].ae_perm & ACL_WRITE)
260 				dac_granted |= (VWRITE | VAPPEND);
261 			dac_granted  &= acl_mask_granted;
262 
263 			if ((accmode & dac_granted) == accmode)
264 				return (0);
265 
266 			group_matched = 1;
267 			break;
268 
269 		default:
270 			break;
271 		}
272 	}
273 
274 	if (group_matched == 1) {
275 		/*
276 		 * There was a match, but it did not grant rights via pure
277 		 * DAC.  Try again, this time with privilege.
278 		 */
279 		for (i = 0; i < acl->acl_cnt; i++) {
280 			switch (acl->acl_entry[i].ae_tag) {
281 			case ACL_GROUP_OBJ:
282 				if (!groupmember(file_gid, cred))
283 					break;
284 				dac_granted = 0;
285 				if (acl->acl_entry[i].ae_perm & ACL_EXECUTE)
286 					dac_granted |= VEXEC;
287 				if (acl->acl_entry[i].ae_perm & ACL_READ)
288 					dac_granted |= VREAD;
289 				if (acl->acl_entry[i].ae_perm & ACL_WRITE)
290 					dac_granted |= (VWRITE | VAPPEND);
291 				dac_granted &= acl_mask_granted;
292 
293 				/*
294 				 * XXXRW: Do privilege lookup here.
295 				 */
296 				if ((accmode & (dac_granted | priv_granted))
297 				    != accmode)
298 					break;
299 
300 				return (0);
301 
302 			case ACL_GROUP:
303 				if (!groupmember(acl->acl_entry[i].ae_id,
304 				    cred))
305 					break;
306 				dac_granted = 0;
307 				if (acl->acl_entry[i].ae_perm & ACL_EXECUTE)
308 				dac_granted |= VEXEC;
309 				if (acl->acl_entry[i].ae_perm & ACL_READ)
310 					dac_granted |= VREAD;
311 				if (acl->acl_entry[i].ae_perm & ACL_WRITE)
312 					dac_granted |= (VWRITE | VAPPEND);
313 				dac_granted &= acl_mask_granted;
314 
315 				/*
316 				 * XXXRW: Do privilege lookup here.
317 				 */
318 				if ((accmode & (dac_granted | priv_granted))
319 				    != accmode)
320 					break;
321 
322 				return (0);
323 
324 			default:
325 				break;
326 			}
327 		}
328 		/*
329 		 * Even with privilege, group membership was not sufficient.
330 		 * Return failure.
331 		 */
332 		goto error;
333 	}
334 
335 	/*
336 	 * Fall back on ACL_OTHER.  ACL_MASK is not applied to ACL_OTHER.
337 	 */
338 	dac_granted = 0;
339 	if (acl_other->ae_perm & ACL_EXECUTE)
340 		dac_granted |= VEXEC;
341 	if (acl_other->ae_perm & ACL_READ)
342 		dac_granted |= VREAD;
343 	if (acl_other->ae_perm & ACL_WRITE)
344 		dac_granted |= (VWRITE | VAPPEND);
345 
346 	if ((accmode & dac_granted) == accmode)
347 		return (0);
348 	/*
349 	 * XXXRW: Do privilege lookup here.
350 	 */
351 	if ((accmode & (dac_granted | priv_granted)) == accmode) {
352 		return (0);
353 	}
354 
355 error:
356 	return ((accmode & VADMIN) ? EPERM : EACCES);
357 }
358 
359 /*
360  * For the purposes of filesystems maintaining the _OBJ entries in an inode
361  * with a mode_t field, this routine converts a mode_t entry to an
362  * acl_perm_t.
363  */
364 acl_perm_t
365 acl_posix1e_mode_to_perm(acl_tag_t tag, mode_t mode)
366 {
367 	acl_perm_t	perm = 0;
368 
369 	switch(tag) {
370 	case ACL_USER_OBJ:
371 		if (mode & S_IXUSR)
372 			perm |= ACL_EXECUTE;
373 		if (mode & S_IRUSR)
374 			perm |= ACL_READ;
375 		if (mode & S_IWUSR)
376 			perm |= ACL_WRITE;
377 		return (perm);
378 
379 	case ACL_GROUP_OBJ:
380 		if (mode & S_IXGRP)
381 			perm |= ACL_EXECUTE;
382 		if (mode & S_IRGRP)
383 			perm |= ACL_READ;
384 		if (mode & S_IWGRP)
385 			perm |= ACL_WRITE;
386 		return (perm);
387 
388 	case ACL_OTHER:
389 		if (mode & S_IXOTH)
390 			perm |= ACL_EXECUTE;
391 		if (mode & S_IROTH)
392 			perm |= ACL_READ;
393 		if (mode & S_IWOTH)
394 			perm |= ACL_WRITE;
395 		return (perm);
396 
397 	default:
398 		printf("acl_posix1e_mode_to_perm: invalid tag (%d)\n", tag);
399 		return (0);
400 	}
401 }
402 
403 /*
404  * Given inode information (uid, gid, mode), return an acl entry of the
405  * appropriate type.
406  */
407 struct acl_entry
408 acl_posix1e_mode_to_entry(acl_tag_t tag, uid_t uid, gid_t gid, mode_t mode)
409 {
410 	struct acl_entry	acl_entry;
411 
412 	acl_entry.ae_tag = tag;
413 	acl_entry.ae_perm = acl_posix1e_mode_to_perm(tag, mode);
414 	acl_entry.ae_entry_type = 0;
415 	acl_entry.ae_flags = 0;
416 	switch(tag) {
417 	case ACL_USER_OBJ:
418 		acl_entry.ae_id = uid;
419 		break;
420 
421 	case ACL_GROUP_OBJ:
422 		acl_entry.ae_id = gid;
423 		break;
424 
425 	case ACL_OTHER:
426 		acl_entry.ae_id = ACL_UNDEFINED_ID;
427 		break;
428 
429 	default:
430 		acl_entry.ae_id = ACL_UNDEFINED_ID;
431 		printf("acl_posix1e_mode_to_entry: invalid tag (%d)\n", tag);
432 	}
433 
434 	return (acl_entry);
435 }
436 
437 /*
438  * Utility function to generate a file mode given appropriate ACL entries.
439  */
440 mode_t
441 acl_posix1e_perms_to_mode(struct acl_entry *acl_user_obj_entry,
442     struct acl_entry *acl_group_obj_entry, struct acl_entry *acl_other_entry)
443 {
444 	mode_t	mode;
445 
446 	mode = 0;
447 	if (acl_user_obj_entry->ae_perm & ACL_EXECUTE)
448 		mode |= S_IXUSR;
449 	if (acl_user_obj_entry->ae_perm & ACL_READ)
450 		mode |= S_IRUSR;
451 	if (acl_user_obj_entry->ae_perm & ACL_WRITE)
452 		mode |= S_IWUSR;
453 	if (acl_group_obj_entry->ae_perm & ACL_EXECUTE)
454 		mode |= S_IXGRP;
455 	if (acl_group_obj_entry->ae_perm & ACL_READ)
456 		mode |= S_IRGRP;
457 	if (acl_group_obj_entry->ae_perm & ACL_WRITE)
458 		mode |= S_IWGRP;
459 	if (acl_other_entry->ae_perm & ACL_EXECUTE)
460 		mode |= S_IXOTH;
461 	if (acl_other_entry->ae_perm & ACL_READ)
462 		mode |= S_IROTH;
463 	if (acl_other_entry->ae_perm & ACL_WRITE)
464 		mode |= S_IWOTH;
465 
466 	return (mode);
467 }
468 
469 /*
470  * Utility function to generate a file mode given a complete POSIX.1e access
471  * ACL.  Note that if the ACL is improperly formed, this may result in a
472  * panic.
473  */
474 mode_t
475 acl_posix1e_acl_to_mode(struct acl *acl)
476 {
477 	struct acl_entry *acl_mask, *acl_user_obj, *acl_group_obj, *acl_other;
478 	int i;
479 
480 	/*
481 	 * Find the ACL entries relevant to a POSIX permission mode.
482 	 */
483 	acl_user_obj = acl_group_obj = acl_other = acl_mask = NULL;
484 	for (i = 0; i < acl->acl_cnt; i++) {
485 		switch (acl->acl_entry[i].ae_tag) {
486 		case ACL_USER_OBJ:
487 			acl_user_obj = &acl->acl_entry[i];
488 			break;
489 
490 		case ACL_GROUP_OBJ:
491 			acl_group_obj = &acl->acl_entry[i];
492 			break;
493 
494 		case ACL_OTHER:
495 			acl_other = &acl->acl_entry[i];
496 			break;
497 
498 		case ACL_MASK:
499 			acl_mask = &acl->acl_entry[i];
500 			break;
501 
502 		case ACL_USER:
503 		case ACL_GROUP:
504 			break;
505 
506 		default:
507 			panic("acl_posix1e_acl_to_mode: bad ae_tag");
508 		}
509 	}
510 
511 	if (acl_user_obj == NULL || acl_group_obj == NULL || acl_other == NULL)
512 		panic("acl_posix1e_acl_to_mode: missing base ae_tags");
513 
514 	/*
515 	 * POSIX.1e specifies that if there is an ACL_MASK entry, we replace
516 	 * the mode "group" bits with its permissions.  If there isn't, we
517 	 * use the ACL_GROUP_OBJ permissions.
518 	 */
519 	if (acl_mask != NULL)
520 		return (acl_posix1e_perms_to_mode(acl_user_obj, acl_mask,
521 		    acl_other));
522 	else
523 		return (acl_posix1e_perms_to_mode(acl_user_obj, acl_group_obj,
524 		    acl_other));
525 }
526 
527 /*
528  * Perform a syntactic check of the ACL, sufficient to allow an implementing
529  * filesystem to determine if it should accept this and rely on the POSIX.1e
530  * ACL properties.
531  */
532 int
533 acl_posix1e_check(struct acl *acl)
534 {
535 	int num_acl_user_obj, num_acl_user, num_acl_group_obj, num_acl_group;
536 	int num_acl_mask, num_acl_other, i;
537 
538 	/*
539 	 * Verify that the number of entries does not exceed the maximum
540 	 * defined for acl_t.
541 	 *
542 	 * Verify that the correct number of various sorts of ae_tags are
543 	 * present:
544 	 *   Exactly one ACL_USER_OBJ
545 	 *   Exactly one ACL_GROUP_OBJ
546 	 *   Exactly one ACL_OTHER
547 	 *   If any ACL_USER or ACL_GROUP entries appear, then exactly one
548 	 *   ACL_MASK entry must also appear.
549 	 *
550 	 * Verify that all ae_perm entries are in ACL_PERM_BITS.
551 	 *
552 	 * Verify all ae_tag entries are understood by this implementation.
553 	 *
554 	 * Note: Does not check for uniqueness of qualifier (ae_id) field.
555 	 */
556 	num_acl_user_obj = num_acl_user = num_acl_group_obj = num_acl_group =
557 	    num_acl_mask = num_acl_other = 0;
558 	if (acl->acl_cnt > ACL_MAX_ENTRIES)
559 		return (EINVAL);
560 	for (i = 0; i < acl->acl_cnt; i++) {
561 		/*
562 		 * Check for a valid tag.
563 		 */
564 		switch(acl->acl_entry[i].ae_tag) {
565 		case ACL_USER_OBJ:
566 			acl->acl_entry[i].ae_id = ACL_UNDEFINED_ID; /* XXX */
567 			if (acl->acl_entry[i].ae_id != ACL_UNDEFINED_ID)
568 				return (EINVAL);
569 			num_acl_user_obj++;
570 			break;
571 		case ACL_GROUP_OBJ:
572 			acl->acl_entry[i].ae_id = ACL_UNDEFINED_ID; /* XXX */
573 			if (acl->acl_entry[i].ae_id != ACL_UNDEFINED_ID)
574 				return (EINVAL);
575 			num_acl_group_obj++;
576 			break;
577 		case ACL_USER:
578 			if (acl->acl_entry[i].ae_id == ACL_UNDEFINED_ID)
579 				return (EINVAL);
580 			num_acl_user++;
581 			break;
582 		case ACL_GROUP:
583 			if (acl->acl_entry[i].ae_id == ACL_UNDEFINED_ID)
584 				return (EINVAL);
585 			num_acl_group++;
586 			break;
587 		case ACL_OTHER:
588 			acl->acl_entry[i].ae_id = ACL_UNDEFINED_ID; /* XXX */
589 			if (acl->acl_entry[i].ae_id != ACL_UNDEFINED_ID)
590 				return (EINVAL);
591 			num_acl_other++;
592 			break;
593 		case ACL_MASK:
594 			acl->acl_entry[i].ae_id = ACL_UNDEFINED_ID; /* XXX */
595 			if (acl->acl_entry[i].ae_id != ACL_UNDEFINED_ID)
596 				return (EINVAL);
597 			num_acl_mask++;
598 			break;
599 		default:
600 			return (EINVAL);
601 		}
602 		/*
603 		 * Check for valid perm entries.
604 		 */
605 		if ((acl->acl_entry[i].ae_perm | ACL_PERM_BITS) !=
606 		    ACL_PERM_BITS)
607 			return (EINVAL);
608 	}
609 	if ((num_acl_user_obj != 1) || (num_acl_group_obj != 1) ||
610 	    (num_acl_other != 1) || (num_acl_mask != 0 && num_acl_mask != 1))
611 		return (EINVAL);
612 	if (((num_acl_group != 0) || (num_acl_user != 0)) &&
613 	    (num_acl_mask != 1))
614 		return (EINVAL);
615 	return (0);
616 }
617 
618 /*
619  * Given a requested mode for a new object, and a default ACL, combine the
620  * two to produce a new mode.  Be careful not to clear any bits that aren't
621  * intended to be affected by the POSIX.1e ACL.  Eventually, this might also
622  * take the cmask as an argument, if we push that down into
623  * per-filesystem-code.
624  */
625 mode_t
626 acl_posix1e_newfilemode(mode_t cmode, struct acl *dacl)
627 {
628 	mode_t mode;
629 
630 	mode = cmode;
631 	/*
632 	 * The current composition policy is that a permission bit must be
633 	 * set in *both* the ACL and the requested creation mode for it to
634 	 * appear in the resulting mode/ACL.  First clear any possibly
635 	 * effected bits, then reconstruct.
636 	 */
637 	mode &= ACL_PRESERVE_MASK;
638 	mode |= (ACL_OVERRIDE_MASK & cmode & acl_posix1e_acl_to_mode(dacl));
639 
640 	return (mode);
641 }
642 
643 static int
644 acl_posix1e_modload(module_t mod, int what, void *arg)
645 {
646 	int ret;
647 
648 	ret = 0;
649 
650 	switch (what) {
651 	case MOD_LOAD:
652 	case MOD_SHUTDOWN:
653 		break;
654 
655 	case MOD_QUIESCE:
656 		/* XXX TODO */
657 		ret = 0;
658 		break;
659 
660 	case MOD_UNLOAD:
661 		/* XXX TODO */
662 		ret = 0;
663 		break;
664 	default:
665 		ret = EINVAL;
666 		break;
667 	}
668 
669 	return (ret);
670 }
671 
672 static moduledata_t acl_posix1e_mod = {
673 	"acl_posix1e",
674 	acl_posix1e_modload,
675 	NULL
676 };
677 
678 DECLARE_MODULE(acl_posix1e, acl_posix1e_mod, SI_SUB_VFS, SI_ORDER_FIRST);
679 MODULE_VERSION(acl_posix1e, 1);
680