xref: /openbmc/linux/fs/xfs/xfs_acl.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
1 /*
2  * Copyright (c) 2001-2002,2005 Silicon Graphics, Inc.
3  * All Rights Reserved.
4  *
5  * This program is free software; you can redistribute it and/or
6  * modify it under the terms of the GNU General Public License as
7  * published by the Free Software Foundation.
8  *
9  * This program is distributed in the hope that it would be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12  * GNU General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write the Free Software Foundation,
16  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
17  */
18 #include "xfs.h"
19 #include "xfs_fs.h"
20 #include "xfs_types.h"
21 #include "xfs_bit.h"
22 #include "xfs_inum.h"
23 #include "xfs_ag.h"
24 #include "xfs_dir.h"
25 #include "xfs_dir2.h"
26 #include "xfs_bmap_btree.h"
27 #include "xfs_alloc_btree.h"
28 #include "xfs_ialloc_btree.h"
29 #include "xfs_dir_sf.h"
30 #include "xfs_dir2_sf.h"
31 #include "xfs_attr_sf.h"
32 #include "xfs_dinode.h"
33 #include "xfs_inode.h"
34 #include "xfs_btree.h"
35 #include "xfs_acl.h"
36 #include "xfs_mac.h"
37 #include "xfs_attr.h"
38 
39 #include <linux/posix_acl_xattr.h>
40 
41 STATIC int	xfs_acl_setmode(vnode_t *, xfs_acl_t *, int *);
42 STATIC void     xfs_acl_filter_mode(mode_t, xfs_acl_t *);
43 STATIC void	xfs_acl_get_endian(xfs_acl_t *);
44 STATIC int	xfs_acl_access(uid_t, gid_t, xfs_acl_t *, mode_t, cred_t *);
45 STATIC int	xfs_acl_invalid(xfs_acl_t *);
46 STATIC void	xfs_acl_sync_mode(mode_t, xfs_acl_t *);
47 STATIC void	xfs_acl_get_attr(vnode_t *, xfs_acl_t *, int, int, int *);
48 STATIC void	xfs_acl_set_attr(vnode_t *, xfs_acl_t *, int, int *);
49 STATIC int	xfs_acl_allow_set(vnode_t *, int);
50 
51 kmem_zone_t *xfs_acl_zone;
52 
53 
54 /*
55  * Test for existence of access ACL attribute as efficiently as possible.
56  */
57 int
58 xfs_acl_vhasacl_access(
59 	vnode_t		*vp)
60 {
61 	int		error;
62 
63 	xfs_acl_get_attr(vp, NULL, _ACL_TYPE_ACCESS, ATTR_KERNOVAL, &error);
64 	return (error == 0);
65 }
66 
67 /*
68  * Test for existence of default ACL attribute as efficiently as possible.
69  */
70 int
71 xfs_acl_vhasacl_default(
72 	vnode_t		*vp)
73 {
74 	int		error;
75 
76 	if (!VN_ISDIR(vp))
77 		return 0;
78 	xfs_acl_get_attr(vp, NULL, _ACL_TYPE_DEFAULT, ATTR_KERNOVAL, &error);
79 	return (error == 0);
80 }
81 
82 /*
83  * Convert from extended attribute representation to in-memory for XFS.
84  */
85 STATIC int
86 posix_acl_xattr_to_xfs(
87 	posix_acl_xattr_header	*src,
88 	size_t			size,
89 	xfs_acl_t		*dest)
90 {
91 	posix_acl_xattr_entry	*src_entry;
92 	xfs_acl_entry_t		*dest_entry;
93 	int			n;
94 
95 	if (!src || !dest)
96 		return EINVAL;
97 
98 	if (size < sizeof(posix_acl_xattr_header))
99 		return EINVAL;
100 
101 	if (src->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
102 		return EOPNOTSUPP;
103 
104 	memset(dest, 0, sizeof(xfs_acl_t));
105 	dest->acl_cnt = posix_acl_xattr_count(size);
106 	if (dest->acl_cnt < 0 || dest->acl_cnt > XFS_ACL_MAX_ENTRIES)
107 		return EINVAL;
108 
109 	/*
110 	 * acl_set_file(3) may request that we set default ACLs with
111 	 * zero length -- defend (gracefully) against that here.
112 	 */
113 	if (!dest->acl_cnt)
114 		return 0;
115 
116 	src_entry = (posix_acl_xattr_entry *)((char *)src + sizeof(*src));
117 	dest_entry = &dest->acl_entry[0];
118 
119 	for (n = 0; n < dest->acl_cnt; n++, src_entry++, dest_entry++) {
120 		dest_entry->ae_perm = le16_to_cpu(src_entry->e_perm);
121 		if (_ACL_PERM_INVALID(dest_entry->ae_perm))
122 			return EINVAL;
123 		dest_entry->ae_tag  = le16_to_cpu(src_entry->e_tag);
124 		switch(dest_entry->ae_tag) {
125 		case ACL_USER:
126 		case ACL_GROUP:
127 			dest_entry->ae_id = le32_to_cpu(src_entry->e_id);
128 			break;
129 		case ACL_USER_OBJ:
130 		case ACL_GROUP_OBJ:
131 		case ACL_MASK:
132 		case ACL_OTHER:
133 			dest_entry->ae_id = ACL_UNDEFINED_ID;
134 			break;
135 		default:
136 			return EINVAL;
137 		}
138 	}
139 	if (xfs_acl_invalid(dest))
140 		return EINVAL;
141 
142 	return 0;
143 }
144 
145 /*
146  * Comparison function called from xfs_sort().
147  * Primary key is ae_tag, secondary key is ae_id.
148  */
149 STATIC int
150 xfs_acl_entry_compare(
151 	const void	*va,
152 	const void	*vb)
153 {
154 	xfs_acl_entry_t	*a = (xfs_acl_entry_t *)va,
155 			*b = (xfs_acl_entry_t *)vb;
156 
157 	if (a->ae_tag == b->ae_tag)
158 		return (a->ae_id - b->ae_id);
159 	return (a->ae_tag - b->ae_tag);
160 }
161 
162 /*
163  * Convert from in-memory XFS to extended attribute representation.
164  */
165 STATIC int
166 posix_acl_xfs_to_xattr(
167 	xfs_acl_t		*src,
168 	posix_acl_xattr_header	*dest,
169 	size_t			size)
170 {
171 	int			n;
172 	size_t			new_size = posix_acl_xattr_size(src->acl_cnt);
173 	posix_acl_xattr_entry	*dest_entry;
174 	xfs_acl_entry_t		*src_entry;
175 
176 	if (size < new_size)
177 		return -ERANGE;
178 
179 	/* Need to sort src XFS ACL by <ae_tag,ae_id> */
180 	xfs_sort(src->acl_entry, src->acl_cnt, sizeof(src->acl_entry[0]),
181 		 xfs_acl_entry_compare);
182 
183 	dest->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
184 	dest_entry = &dest->a_entries[0];
185 	src_entry = &src->acl_entry[0];
186 	for (n = 0; n < src->acl_cnt; n++, dest_entry++, src_entry++) {
187 		dest_entry->e_perm = cpu_to_le16(src_entry->ae_perm);
188 		if (_ACL_PERM_INVALID(src_entry->ae_perm))
189 			return -EINVAL;
190 		dest_entry->e_tag  = cpu_to_le16(src_entry->ae_tag);
191 		switch (src_entry->ae_tag) {
192 		case ACL_USER:
193 		case ACL_GROUP:
194 			dest_entry->e_id = cpu_to_le32(src_entry->ae_id);
195 				break;
196 		case ACL_USER_OBJ:
197 		case ACL_GROUP_OBJ:
198 		case ACL_MASK:
199 		case ACL_OTHER:
200 			dest_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
201 			break;
202 		default:
203 			return -EINVAL;
204 		}
205 	}
206 	return new_size;
207 }
208 
209 int
210 xfs_acl_vget(
211 	vnode_t		*vp,
212 	void		*acl,
213 	size_t		size,
214 	int		kind)
215 {
216 	int			error;
217 	xfs_acl_t		*xfs_acl = NULL;
218 	posix_acl_xattr_header	*ext_acl = acl;
219 	int			flags = 0;
220 
221 	VN_HOLD(vp);
222 	if(size) {
223 		if (!(_ACL_ALLOC(xfs_acl))) {
224 			error = ENOMEM;
225 			goto out;
226 		}
227 		memset(xfs_acl, 0, sizeof(xfs_acl_t));
228 	} else
229 		flags = ATTR_KERNOVAL;
230 
231 	xfs_acl_get_attr(vp, xfs_acl, kind, flags, &error);
232 	if (error)
233 		goto out;
234 
235 	if (!size) {
236 		error = -posix_acl_xattr_size(XFS_ACL_MAX_ENTRIES);
237 	} else {
238 		if (xfs_acl_invalid(xfs_acl)) {
239 			error = EINVAL;
240 			goto out;
241 		}
242 		if (kind == _ACL_TYPE_ACCESS) {
243 			vattr_t	va;
244 
245 			va.va_mask = XFS_AT_MODE;
246 			VOP_GETATTR(vp, &va, 0, sys_cred, error);
247 			if (error)
248 				goto out;
249 			xfs_acl_sync_mode(va.va_mode, xfs_acl);
250 		}
251 		error = -posix_acl_xfs_to_xattr(xfs_acl, ext_acl, size);
252 	}
253 out:
254 	VN_RELE(vp);
255 	if(xfs_acl)
256 		_ACL_FREE(xfs_acl);
257 	return -error;
258 }
259 
260 int
261 xfs_acl_vremove(
262 	vnode_t		*vp,
263 	int		kind)
264 {
265 	int		error;
266 
267 	VN_HOLD(vp);
268 	error = xfs_acl_allow_set(vp, kind);
269 	if (!error) {
270 		VOP_ATTR_REMOVE(vp, kind == _ACL_TYPE_DEFAULT?
271 				SGI_ACL_DEFAULT: SGI_ACL_FILE,
272 				ATTR_ROOT, sys_cred, error);
273 		if (error == ENOATTR)
274 			error = 0;	/* 'scool */
275 	}
276 	VN_RELE(vp);
277 	return -error;
278 }
279 
280 int
281 xfs_acl_vset(
282 	vnode_t			*vp,
283 	void			*acl,
284 	size_t			size,
285 	int			kind)
286 {
287 	posix_acl_xattr_header	*ext_acl = acl;
288 	xfs_acl_t		*xfs_acl;
289 	int			error;
290 	int			basicperms = 0; /* more than std unix perms? */
291 
292 	if (!acl)
293 		return -EINVAL;
294 
295 	if (!(_ACL_ALLOC(xfs_acl)))
296 		return -ENOMEM;
297 
298 	error = posix_acl_xattr_to_xfs(ext_acl, size, xfs_acl);
299 	if (error) {
300 		_ACL_FREE(xfs_acl);
301 		return -error;
302 	}
303 	if (!xfs_acl->acl_cnt) {
304 		_ACL_FREE(xfs_acl);
305 		return 0;
306 	}
307 
308 	VN_HOLD(vp);
309 	error = xfs_acl_allow_set(vp, kind);
310 	if (error)
311 		goto out;
312 
313 	/* Incoming ACL exists, set file mode based on its value */
314 	if (kind == _ACL_TYPE_ACCESS)
315 		xfs_acl_setmode(vp, xfs_acl, &basicperms);
316 
317 	/*
318 	 * If we have more than std unix permissions, set up the actual attr.
319 	 * Otherwise, delete any existing attr.  This prevents us from
320 	 * having actual attrs for permissions that can be stored in the
321 	 * standard permission bits.
322 	 */
323 	if (!basicperms) {
324 		xfs_acl_set_attr(vp, xfs_acl, kind, &error);
325 	} else {
326 		xfs_acl_vremove(vp, _ACL_TYPE_ACCESS);
327 	}
328 
329 out:
330 	VN_RELE(vp);
331 	_ACL_FREE(xfs_acl);
332 	return -error;
333 }
334 
335 int
336 xfs_acl_iaccess(
337 	xfs_inode_t	*ip,
338 	mode_t		mode,
339 	cred_t		*cr)
340 {
341 	xfs_acl_t	*acl;
342 	int		rval;
343 
344 	if (!(_ACL_ALLOC(acl)))
345 		return -1;
346 
347 	/* If the file has no ACL return -1. */
348 	rval = sizeof(xfs_acl_t);
349 	if (xfs_attr_fetch(ip, SGI_ACL_FILE, SGI_ACL_FILE_SIZE,
350 			(char *)acl, &rval, ATTR_ROOT | ATTR_KERNACCESS, cr)) {
351 		_ACL_FREE(acl);
352 		return -1;
353 	}
354 	xfs_acl_get_endian(acl);
355 
356 	/* If the file has an empty ACL return -1. */
357 	if (acl->acl_cnt == XFS_ACL_NOT_PRESENT) {
358 		_ACL_FREE(acl);
359 		return -1;
360 	}
361 
362 	/* Synchronize ACL with mode bits */
363 	xfs_acl_sync_mode(ip->i_d.di_mode, acl);
364 
365 	rval = xfs_acl_access(ip->i_d.di_uid, ip->i_d.di_gid, acl, mode, cr);
366 	_ACL_FREE(acl);
367 	return rval;
368 }
369 
370 STATIC int
371 xfs_acl_allow_set(
372 	vnode_t		*vp,
373 	int		kind)
374 {
375 	vattr_t		va;
376 	int		error;
377 
378 	if (vp->v_inode.i_flags & (S_IMMUTABLE|S_APPEND))
379 		return EPERM;
380 	if (kind == _ACL_TYPE_DEFAULT && !VN_ISDIR(vp))
381 		return ENOTDIR;
382 	if (vp->v_vfsp->vfs_flag & VFS_RDONLY)
383 		return EROFS;
384 	va.va_mask = XFS_AT_UID;
385 	VOP_GETATTR(vp, &va, 0, NULL, error);
386 	if (error)
387 		return error;
388 	if (va.va_uid != current->fsuid && !capable(CAP_FOWNER))
389 		return EPERM;
390 	return error;
391 }
392 
393 /*
394  * The access control process to determine the access permission:
395  *	if uid == file owner id, use the file owner bits.
396  *	if gid == file owner group id, use the file group bits.
397  *	scan ACL for a maching user or group, and use matched entry
398  *	permission. Use total permissions of all matching group entries,
399  *	until all acl entries are exhausted. The final permission produced
400  *	by matching acl entry or entries needs to be & with group permission.
401  *	if not owner, owning group, or matching entry in ACL, use file
402  *	other bits.
403  */
404 STATIC int
405 xfs_acl_capability_check(
406 	mode_t		mode,
407 	cred_t		*cr)
408 {
409 	if ((mode & ACL_READ) && !capable_cred(cr, CAP_DAC_READ_SEARCH))
410 		return EACCES;
411 	if ((mode & ACL_WRITE) && !capable_cred(cr, CAP_DAC_OVERRIDE))
412 		return EACCES;
413 	if ((mode & ACL_EXECUTE) && !capable_cred(cr, CAP_DAC_OVERRIDE))
414 		return EACCES;
415 
416 	return 0;
417 }
418 
419 /*
420  * Note: cr is only used here for the capability check if the ACL test fails.
421  *       It is not used to find out the credentials uid or groups etc, as was
422  *       done in IRIX. It is assumed that the uid and groups for the current
423  *       thread are taken from "current" instead of the cr parameter.
424  */
425 STATIC int
426 xfs_acl_access(
427 	uid_t		fuid,
428 	gid_t		fgid,
429 	xfs_acl_t	*fap,
430 	mode_t		md,
431 	cred_t		*cr)
432 {
433 	xfs_acl_entry_t	matched;
434 	int		i, allows;
435 	int		maskallows = -1;	/* true, but not 1, either */
436 	int		seen_userobj = 0;
437 
438 	matched.ae_tag = 0;	/* Invalid type */
439 	matched.ae_perm = 0;
440 	md >>= 6;	/* Normalize the bits for comparison */
441 
442 	for (i = 0; i < fap->acl_cnt; i++) {
443 		/*
444 		 * Break out if we've got a user_obj entry or
445 		 * a user entry and the mask (and have processed USER_OBJ)
446 		 */
447 		if (matched.ae_tag == ACL_USER_OBJ)
448 			break;
449 		if (matched.ae_tag == ACL_USER) {
450 			if (maskallows != -1 && seen_userobj)
451 				break;
452 			if (fap->acl_entry[i].ae_tag != ACL_MASK &&
453 			    fap->acl_entry[i].ae_tag != ACL_USER_OBJ)
454 				continue;
455 		}
456 		/* True if this entry allows the requested access */
457 		allows = ((fap->acl_entry[i].ae_perm & md) == md);
458 
459 		switch (fap->acl_entry[i].ae_tag) {
460 		case ACL_USER_OBJ:
461 			seen_userobj = 1;
462 			if (fuid != current->fsuid)
463 				continue;
464 			matched.ae_tag = ACL_USER_OBJ;
465 			matched.ae_perm = allows;
466 			break;
467 		case ACL_USER:
468 			if (fap->acl_entry[i].ae_id != current->fsuid)
469 				continue;
470 			matched.ae_tag = ACL_USER;
471 			matched.ae_perm = allows;
472 			break;
473 		case ACL_GROUP_OBJ:
474 			if ((matched.ae_tag == ACL_GROUP_OBJ ||
475 			    matched.ae_tag == ACL_GROUP) && !allows)
476 				continue;
477 			if (!in_group_p(fgid))
478 				continue;
479 			matched.ae_tag = ACL_GROUP_OBJ;
480 			matched.ae_perm = allows;
481 			break;
482 		case ACL_GROUP:
483 			if ((matched.ae_tag == ACL_GROUP_OBJ ||
484 			    matched.ae_tag == ACL_GROUP) && !allows)
485 				continue;
486 			if (!in_group_p(fap->acl_entry[i].ae_id))
487 				continue;
488 			matched.ae_tag = ACL_GROUP;
489 			matched.ae_perm = allows;
490 			break;
491 		case ACL_MASK:
492 			maskallows = allows;
493 			break;
494 		case ACL_OTHER:
495 			if (matched.ae_tag != 0)
496 				continue;
497 			matched.ae_tag = ACL_OTHER;
498 			matched.ae_perm = allows;
499 			break;
500 		}
501 	}
502 	/*
503 	 * First possibility is that no matched entry allows access.
504 	 * The capability to override DAC may exist, so check for it.
505 	 */
506 	switch (matched.ae_tag) {
507 	case ACL_OTHER:
508 	case ACL_USER_OBJ:
509 		if (matched.ae_perm)
510 			return 0;
511 		break;
512 	case ACL_USER:
513 	case ACL_GROUP_OBJ:
514 	case ACL_GROUP:
515 		if (maskallows && matched.ae_perm)
516 			return 0;
517 		break;
518 	case 0:
519 		break;
520 	}
521 
522 	return xfs_acl_capability_check(md, cr);
523 }
524 
525 /*
526  * ACL validity checker.
527  *   This acl validation routine checks each ACL entry read in makes sense.
528  */
529 STATIC int
530 xfs_acl_invalid(
531 	xfs_acl_t	*aclp)
532 {
533 	xfs_acl_entry_t	*entry, *e;
534 	int		user = 0, group = 0, other = 0, mask = 0;
535 	int		mask_required = 0;
536 	int		i, j;
537 
538 	if (!aclp)
539 		goto acl_invalid;
540 
541 	if (aclp->acl_cnt > XFS_ACL_MAX_ENTRIES)
542 		goto acl_invalid;
543 
544 	for (i = 0; i < aclp->acl_cnt; i++) {
545 		entry = &aclp->acl_entry[i];
546 		switch (entry->ae_tag) {
547 		case ACL_USER_OBJ:
548 			if (user++)
549 				goto acl_invalid;
550 			break;
551 		case ACL_GROUP_OBJ:
552 			if (group++)
553 				goto acl_invalid;
554 			break;
555 		case ACL_OTHER:
556 			if (other++)
557 				goto acl_invalid;
558 			break;
559 		case ACL_USER:
560 		case ACL_GROUP:
561 			for (j = i + 1; j < aclp->acl_cnt; j++) {
562 				e = &aclp->acl_entry[j];
563 				if (e->ae_id == entry->ae_id &&
564 				    e->ae_tag == entry->ae_tag)
565 					goto acl_invalid;
566 			}
567 			mask_required++;
568 			break;
569 		case ACL_MASK:
570 			if (mask++)
571 				goto acl_invalid;
572 			break;
573 		default:
574 			goto acl_invalid;
575 		}
576 	}
577 	if (!user || !group || !other || (mask_required && !mask))
578 		goto acl_invalid;
579 	else
580 		return 0;
581 acl_invalid:
582 	return EINVAL;
583 }
584 
585 /*
586  * Do ACL endian conversion.
587  */
588 STATIC void
589 xfs_acl_get_endian(
590 	xfs_acl_t	*aclp)
591 {
592 	xfs_acl_entry_t	*ace, *end;
593 
594 	INT_SET(aclp->acl_cnt, ARCH_CONVERT, aclp->acl_cnt);
595 	end = &aclp->acl_entry[0]+aclp->acl_cnt;
596 	for (ace = &aclp->acl_entry[0]; ace < end; ace++) {
597 		INT_SET(ace->ae_tag, ARCH_CONVERT, ace->ae_tag);
598 		INT_SET(ace->ae_id, ARCH_CONVERT, ace->ae_id);
599 		INT_SET(ace->ae_perm, ARCH_CONVERT, ace->ae_perm);
600 	}
601 }
602 
603 /*
604  * Get the ACL from the EA and do endian conversion.
605  */
606 STATIC void
607 xfs_acl_get_attr(
608 	vnode_t		*vp,
609 	xfs_acl_t	*aclp,
610 	int		kind,
611 	int		flags,
612 	int		*error)
613 {
614 	int		len = sizeof(xfs_acl_t);
615 
616 	ASSERT((flags & ATTR_KERNOVAL) ? (aclp == NULL) : 1);
617 	flags |= ATTR_ROOT;
618 	VOP_ATTR_GET(vp,
619 		kind == _ACL_TYPE_ACCESS ? SGI_ACL_FILE : SGI_ACL_DEFAULT,
620 		(char *)aclp, &len, flags, sys_cred, *error);
621 	if (*error || (flags & ATTR_KERNOVAL))
622 		return;
623 	xfs_acl_get_endian(aclp);
624 }
625 
626 /*
627  * Set the EA with the ACL and do endian conversion.
628  */
629 STATIC void
630 xfs_acl_set_attr(
631 	vnode_t		*vp,
632 	xfs_acl_t	*aclp,
633 	int		kind,
634 	int		*error)
635 {
636 	xfs_acl_entry_t	*ace, *newace, *end;
637 	xfs_acl_t	*newacl;
638 	int		len;
639 
640 	if (!(_ACL_ALLOC(newacl))) {
641 		*error = ENOMEM;
642 		return;
643 	}
644 
645 	len = sizeof(xfs_acl_t) -
646 	      (sizeof(xfs_acl_entry_t) * (XFS_ACL_MAX_ENTRIES - aclp->acl_cnt));
647 	end = &aclp->acl_entry[0]+aclp->acl_cnt;
648 	for (ace = &aclp->acl_entry[0], newace = &newacl->acl_entry[0];
649 	     ace < end;
650 	     ace++, newace++) {
651 		INT_SET(newace->ae_tag, ARCH_CONVERT, ace->ae_tag);
652 		INT_SET(newace->ae_id, ARCH_CONVERT, ace->ae_id);
653 		INT_SET(newace->ae_perm, ARCH_CONVERT, ace->ae_perm);
654 	}
655 	INT_SET(newacl->acl_cnt, ARCH_CONVERT, aclp->acl_cnt);
656 	VOP_ATTR_SET(vp,
657 		kind == _ACL_TYPE_ACCESS ? SGI_ACL_FILE: SGI_ACL_DEFAULT,
658 		(char *)newacl, len, ATTR_ROOT, sys_cred, *error);
659 	_ACL_FREE(newacl);
660 }
661 
662 int
663 xfs_acl_vtoacl(
664 	vnode_t		*vp,
665 	xfs_acl_t	*access_acl,
666 	xfs_acl_t	*default_acl)
667 {
668 	vattr_t		va;
669 	int		error = 0;
670 
671 	if (access_acl) {
672 		/*
673 		 * Get the Access ACL and the mode.  If either cannot
674 		 * be obtained for some reason, invalidate the access ACL.
675 		 */
676 		xfs_acl_get_attr(vp, access_acl, _ACL_TYPE_ACCESS, 0, &error);
677 		if (!error) {
678 			/* Got the ACL, need the mode... */
679 			va.va_mask = XFS_AT_MODE;
680 			VOP_GETATTR(vp, &va, 0, sys_cred, error);
681 		}
682 
683 		if (error)
684 			access_acl->acl_cnt = XFS_ACL_NOT_PRESENT;
685 		else /* We have a good ACL and the file mode, synchronize. */
686 			xfs_acl_sync_mode(va.va_mode, access_acl);
687 	}
688 
689 	if (default_acl) {
690 		xfs_acl_get_attr(vp, default_acl, _ACL_TYPE_DEFAULT, 0, &error);
691 		if (error)
692 			default_acl->acl_cnt = XFS_ACL_NOT_PRESENT;
693 	}
694 	return error;
695 }
696 
697 /*
698  * This function retrieves the parent directory's acl, processes it
699  * and lets the child inherit the acl(s) that it should.
700  */
701 int
702 xfs_acl_inherit(
703 	vnode_t		*vp,
704 	vattr_t		*vap,
705 	xfs_acl_t	*pdaclp)
706 {
707 	xfs_acl_t	*cacl;
708 	int		error = 0;
709 	int		basicperms = 0;
710 
711 	/*
712 	 * If the parent does not have a default ACL, or it's an
713 	 * invalid ACL, we're done.
714 	 */
715 	if (!vp)
716 		return 0;
717 	if (!pdaclp || xfs_acl_invalid(pdaclp))
718 		return 0;
719 
720 	/*
721 	 * Copy the default ACL of the containing directory to
722 	 * the access ACL of the new file and use the mode that
723 	 * was passed in to set up the correct initial values for
724 	 * the u::,g::[m::], and o:: entries.  This is what makes
725 	 * umask() "work" with ACL's.
726 	 */
727 
728 	if (!(_ACL_ALLOC(cacl)))
729 		return ENOMEM;
730 
731 	memcpy(cacl, pdaclp, sizeof(xfs_acl_t));
732 	xfs_acl_filter_mode(vap->va_mode, cacl);
733 	xfs_acl_setmode(vp, cacl, &basicperms);
734 
735 	/*
736 	 * Set the Default and Access ACL on the file.  The mode is already
737 	 * set on the file, so we don't need to worry about that.
738 	 *
739 	 * If the new file is a directory, its default ACL is a copy of
740 	 * the containing directory's default ACL.
741 	 */
742 	if (VN_ISDIR(vp))
743 		xfs_acl_set_attr(vp, pdaclp, _ACL_TYPE_DEFAULT, &error);
744 	if (!error && !basicperms)
745 		xfs_acl_set_attr(vp, cacl, _ACL_TYPE_ACCESS, &error);
746 	_ACL_FREE(cacl);
747 	return error;
748 }
749 
750 /*
751  * Set up the correct mode on the file based on the supplied ACL.  This
752  * makes sure that the mode on the file reflects the state of the
753  * u::,g::[m::], and o:: entries in the ACL.  Since the mode is where
754  * the ACL is going to get the permissions for these entries, we must
755  * synchronize the mode whenever we set the ACL on a file.
756  */
757 STATIC int
758 xfs_acl_setmode(
759 	vnode_t		*vp,
760 	xfs_acl_t	*acl,
761 	int		*basicperms)
762 {
763 	vattr_t		va;
764 	xfs_acl_entry_t	*ap;
765 	xfs_acl_entry_t	*gap = NULL;
766 	int		i, error, nomask = 1;
767 
768 	*basicperms = 1;
769 
770 	if (acl->acl_cnt == XFS_ACL_NOT_PRESENT)
771 		return 0;
772 
773 	/*
774 	 * Copy the u::, g::, o::, and m:: bits from the ACL into the
775 	 * mode.  The m:: bits take precedence over the g:: bits.
776 	 */
777 	va.va_mask = XFS_AT_MODE;
778 	VOP_GETATTR(vp, &va, 0, sys_cred, error);
779 	if (error)
780 		return error;
781 
782 	va.va_mask = XFS_AT_MODE;
783 	va.va_mode &= ~(S_IRWXU|S_IRWXG|S_IRWXO);
784 	ap = acl->acl_entry;
785 	for (i = 0; i < acl->acl_cnt; ++i) {
786 		switch (ap->ae_tag) {
787 		case ACL_USER_OBJ:
788 			va.va_mode |= ap->ae_perm << 6;
789 			break;
790 		case ACL_GROUP_OBJ:
791 			gap = ap;
792 			break;
793 		case ACL_MASK:	/* more than just standard modes */
794 			nomask = 0;
795 			va.va_mode |= ap->ae_perm << 3;
796 			*basicperms = 0;
797 			break;
798 		case ACL_OTHER:
799 			va.va_mode |= ap->ae_perm;
800 			break;
801 		default:	/* more than just standard modes */
802 			*basicperms = 0;
803 			break;
804 		}
805 		ap++;
806 	}
807 
808 	/* Set the group bits from ACL_GROUP_OBJ if there's no ACL_MASK */
809 	if (gap && nomask)
810 		va.va_mode |= gap->ae_perm << 3;
811 
812 	VOP_SETATTR(vp, &va, 0, sys_cred, error);
813 	return error;
814 }
815 
816 /*
817  * The permissions for the special ACL entries (u::, g::[m::], o::) are
818  * actually stored in the file mode (if there is both a group and a mask,
819  * the group is stored in the ACL entry and the mask is stored on the file).
820  * This allows the mode to remain automatically in sync with the ACL without
821  * the need for a call-back to the ACL system at every point where the mode
822  * could change.  This function takes the permissions from the specified mode
823  * and places it in the supplied ACL.
824  *
825  * This implementation draws its validity from the fact that, when the ACL
826  * was assigned, the mode was copied from the ACL.
827  * If the mode did not change, therefore, the mode remains exactly what was
828  * taken from the special ACL entries at assignment.
829  * If a subsequent chmod() was done, the POSIX spec says that the change in
830  * mode must cause an update to the ACL seen at user level and used for
831  * access checks.  Before and after a mode change, therefore, the file mode
832  * most accurately reflects what the special ACL entries should permit/deny.
833  *
834  * CAVEAT: If someone sets the SGI_ACL_FILE attribute directly,
835  *         the existing mode bits will override whatever is in the
836  *         ACL. Similarly, if there is a pre-existing ACL that was
837  *         never in sync with its mode (owing to a bug in 6.5 and
838  *         before), it will now magically (or mystically) be
839  *         synchronized.  This could cause slight astonishment, but
840  *         it is better than inconsistent permissions.
841  *
842  * The supplied ACL is a template that may contain any combination
843  * of special entries.  These are treated as place holders when we fill
844  * out the ACL.  This routine does not add or remove special entries, it
845  * simply unites each special entry with its associated set of permissions.
846  */
847 STATIC void
848 xfs_acl_sync_mode(
849 	mode_t		mode,
850 	xfs_acl_t	*acl)
851 {
852 	int		i, nomask = 1;
853 	xfs_acl_entry_t	*ap;
854 	xfs_acl_entry_t	*gap = NULL;
855 
856 	/*
857 	 * Set ACL entries. POSIX1003.1eD16 requires that the MASK
858 	 * be set instead of the GROUP entry, if there is a MASK.
859 	 */
860 	for (ap = acl->acl_entry, i = 0; i < acl->acl_cnt; ap++, i++) {
861 		switch (ap->ae_tag) {
862 		case ACL_USER_OBJ:
863 			ap->ae_perm = (mode >> 6) & 0x7;
864 			break;
865 		case ACL_GROUP_OBJ:
866 			gap = ap;
867 			break;
868 		case ACL_MASK:
869 			nomask = 0;
870 			ap->ae_perm = (mode >> 3) & 0x7;
871 			break;
872 		case ACL_OTHER:
873 			ap->ae_perm = mode & 0x7;
874 			break;
875 		default:
876 			break;
877 		}
878 	}
879 	/* Set the ACL_GROUP_OBJ if there's no ACL_MASK */
880 	if (gap && nomask)
881 		gap->ae_perm = (mode >> 3) & 0x7;
882 }
883 
884 /*
885  * When inheriting an Access ACL from a directory Default ACL,
886  * the ACL bits are set to the intersection of the ACL default
887  * permission bits and the file permission bits in mode. If there
888  * are no permission bits on the file then we must not give them
889  * the ACL. This is what what makes umask() work with ACLs.
890  */
891 STATIC void
892 xfs_acl_filter_mode(
893 	mode_t		mode,
894 	xfs_acl_t	*acl)
895 {
896 	int		i, nomask = 1;
897 	xfs_acl_entry_t	*ap;
898 	xfs_acl_entry_t	*gap = NULL;
899 
900 	/*
901 	 * Set ACL entries. POSIX1003.1eD16 requires that the MASK
902 	 * be merged with GROUP entry, if there is a MASK.
903 	 */
904 	for (ap = acl->acl_entry, i = 0; i < acl->acl_cnt; ap++, i++) {
905 		switch (ap->ae_tag) {
906 		case ACL_USER_OBJ:
907 			ap->ae_perm &= (mode >> 6) & 0x7;
908 			break;
909 		case ACL_GROUP_OBJ:
910 			gap = ap;
911 			break;
912 		case ACL_MASK:
913 			nomask = 0;
914 			ap->ae_perm &= (mode >> 3) & 0x7;
915 			break;
916 		case ACL_OTHER:
917 			ap->ae_perm &= mode & 0x7;
918 			break;
919 		default:
920 			break;
921 		}
922 	}
923 	/* Set the ACL_GROUP_OBJ if there's no ACL_MASK */
924 	if (gap && nomask)
925 		gap->ae_perm &= (mode >> 3) & 0x7;
926 }
927