aboutsummaryrefslogtreecommitdiff
path: root/fs/cifs/cifsacl.c
blob: c9b4792ae82538761b056ffba55173e77a2f2c8c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
/*
 *   fs/cifs/cifsacl.c
 *
 *   Copyright (C) International Business Machines  Corp., 2007,2008
 *   Author(s): Steve French (sfrench@us.ibm.com)
 *
 *   Contains the routines for mapping CIFS/NTFS ACLs
 *
 *   This library is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Lesser General Public License as published
 *   by the Free Software Foundation; either version 2.1 of the License, or
 *   (at your option) any later version.
 *
 *   This library is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 *   the GNU Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public License
 *   along with this library; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/fs.h>
#include <linux/slab.h>
#include "cifspdu.h"
#include "cifsglob.h"
#include "cifsacl.h"
#include "cifsproto.h"
#include "cifs_debug.h"


#ifdef CONFIG_CIFS_EXPERIMENTAL

static struct cifs_wksid wksidarr[NUM_WK_SIDS] = {
	{{1, 0, {0, 0, 0, 0, 0, 0}, {0, 0, 0, 0, 0} }, "null user"},
	{{1, 1, {0, 0, 0, 0, 0, 1}, {0, 0, 0, 0, 0} }, "nobody"},
	{{1, 1, {0, 0, 0, 0, 0, 5}, {__constant_cpu_to_le32(11), 0, 0, 0, 0} }, "net-users"},
	{{1, 1, {0, 0, 0, 0, 0, 5}, {__constant_cpu_to_le32(18), 0, 0, 0, 0} }, "sys"},
	{{1, 2, {0, 0, 0, 0, 0, 5}, {__constant_cpu_to_le32(32), __constant_cpu_to_le32(544), 0, 0, 0} }, "root"},
	{{1, 2, {0, 0, 0, 0, 0, 5}, {__constant_cpu_to_le32(32), __constant_cpu_to_le32(545), 0, 0, 0} }, "users"},
	{{1, 2, {0, 0, 0, 0, 0, 5}, {__constant_cpu_to_le32(32), __constant_cpu_to_le32(546), 0, 0, 0} }, "guest"} }
;


/* security id for everyone */
static const struct cifs_sid sid_everyone = {
	1, 1, {0, 0, 0, 0, 0, 1}, {0} };
/* group users */
static const struct cifs_sid sid_user = {1, 2 , {0, 0, 0, 0, 0, 5}, {} };


int match_sid(struct cifs_sid *ctsid)
{
	int i, j;
	int num_subauth, num_sat, num_saw;
	struct cifs_sid *cwsid;

	if (!ctsid)
		return -1;

	for (i = 0; i < NUM_WK_SIDS; ++i) {
		cwsid = &(wksidarr[i].cifssid);

		/* compare the revision */
		if (ctsid->revision != cwsid->revision)
			continue;

		/* compare all of the six auth values */
		for (j = 0; j < 6; ++j) {
			if (ctsid->authority[j] != cwsid->authority[j])
				break;
		}
		if (j < 6)
			continue; /* all of the auth values did not match */

		/* compare all of the subauth values if any */
		num_sat = ctsid->num_subauth;
		num_saw = cwsid->num_subauth;
		num_subauth = num_sat < num_saw ? num_sat : num_saw;
		if (num_subauth) {
			for (j = 0; j < num_subauth; ++j) {
				if (ctsid->sub_auth[j] != cwsid->sub_auth[j])
					break;
			}
			if (j < num_subauth)
				continue; /* all sub_auth values do not match */
		}

		cFYI(1, "matching sid: %s\n", wksidarr[i].sidname);
		return 0; /* sids compare/match */
	}

	cFYI(1, "No matching sid");
	return -1;
}

/* if the two SIDs (roughly equivalent to a UUID for a user or group) are
   the same returns 1, if they do not match returns 0 */
int compare_sids(const struct cifs_sid *ctsid, const struct cifs_sid *cwsid)
{
	int i;
	int num_subauth, num_sat, num_saw;

	if ((!ctsid) || (!cwsid))
		return 0;

	/* compare the revision */
	if (ctsid->revision != cwsid->revision)
		return 0;

	/* compare all of the six auth values */
	for (i = 0; i < 6; ++i) {
		if (ctsid->authority[i] != cwsid->authority[i])
			return 0;
	}

	/* compare all of the subauth values if any */
	num_sat = ctsid->num_subauth;
	num_saw = cwsid->num_subauth;
	num_subauth = num_sat < num_saw ? num_sat : num_saw;
	if (num_subauth) {
		for (i = 0; i < num_subauth; ++i) {
			if (ctsid->sub_auth[i] != cwsid->sub_auth[i])
				return 0;
		}
	}

	return 1; /* sids compare/match */
}


/* copy ntsd, owner sid, and group sid from a security descriptor to another */
static void copy_sec_desc(const struct cifs_ntsd *pntsd,
				struct cifs_ntsd *pnntsd, __u32 sidsoffset)
{
	int i;

	struct cifs_sid *owner_sid_ptr, *group_sid_ptr;
	struct cifs_sid *nowner_sid_ptr, *ngroup_sid_ptr;

	/* copy security descriptor control portion */
	pnntsd->revision = pntsd->revision;
	pnntsd->type = pntsd->type;
	pnntsd->dacloffset = cpu_to_le32(sizeof(struct cifs_ntsd));
	pnntsd->sacloffset = 0;
	pnntsd->osidoffset = cpu_to_le32(sidsoffset);
	pnntsd->gsidoffset = cpu_to_le32(sidsoffset + sizeof(struct cifs_sid));

	/* copy owner sid */
	owner_sid_ptr = (struct cifs_sid *)((char *)pntsd +
				le32_to_cpu(pntsd->osidoffset));
	nowner_sid_ptr = (struct cifs_sid *)((char *)pnntsd + sidsoffset);

	nowner_sid_ptr->revision = owner_sid_ptr->revision;
	nowner_sid_ptr->num_subauth = owner_sid_ptr->num_subauth;
	for (i = 0; i < 6; i++)
		nowner_sid_ptr->authority[i] = owner_sid_ptr->authority[i];
	for (i = 0; i < 5; i++)
		nowner_sid_ptr->sub_auth[i] = owner_sid_ptr->sub_auth[i];

	/* copy group sid */
	group_sid_ptr = (struct cifs_sid *)((char *)pntsd +
				le32_to_cpu(pntsd->gsidoffset));
	ngroup_sid_ptr = (struct cifs_sid *)((char *)pnntsd + sidsoffset +
					sizeof(struct cifs_sid));

	ngroup_sid_ptr->revision = group_sid_ptr->revision;
	ngroup_sid_ptr->num_subauth = group_sid_ptr->num_subauth;
	for (i = 0; i < 6; i++)
		ngroup_sid_ptr->authority[i] = group_sid_ptr->authority[i];
	for (i = 0; i < 5; i++)
		ngroup_sid_ptr->sub_auth[i] = group_sid_ptr->sub_auth[i];

	return;
}


/*
   change posix mode to reflect permissions
   pmode is the existing mode (we only want to overwrite part of this
   bits to set can be: S_IRWXU, S_IRWXG or S_IRWXO ie 00700 or 00070 or 00007
*/
static void access_flags_to_mode(__le32 ace_flags, int type, umode_t *pmode,
				 umode_t *pbits_to_set)
{
	__u32 flags = le32_to_cpu(ace_flags);
	/* the order of ACEs is important.  The canonical order is to begin with
	   DENY entries followed by ALLOW, otherwise an allow entry could be
	   encountered first, making the subsequent deny entry like "dead code"
	   which would be superflous since Windows stops when a match is made
	   for the operation you are trying to perform for your user */

	/* For deny ACEs we change the mask so that subsequent allow access
	   control entries do not turn on the bits we are denying */
	if (type == ACCESS_DENIED) {
		if (flags & GENERIC_ALL)
			*pbits_to_set &= ~S_IRWXUGO;

		if ((flags & GENERIC_WRITE) ||
			((flags & FILE_WRITE_RIGHTS) == FILE_WRITE_RIGHTS))
			*pbits_to_set &= ~S_IWUGO;
		if ((flags & GENERIC_READ) ||
			((flags & FILE_READ_RIGHTS) == FILE_READ_RIGHTS))
			*pbits_to_set &= ~S_IRUGO;
		if ((flags & GENERIC_EXECUTE) ||
			((flags & FILE_EXEC_RIGHTS) == FILE_EXEC_RIGHTS))
			*pbits_to_set &= ~S_IXUGO;
		return;
	} else if (type != ACCESS_ALLOWED) {
		cERROR(1, "unknown access control type %d", type);
		return;
	}
	/* else ACCESS_ALLOWED type */

	if (flags & GENERIC_ALL) {
		*pmode |= (S_IRWXUGO & (*pbits_to_set));
		cFYI(DBG2, "all perms");
		return;
	}
	if ((flags & GENERIC_WRITE) ||
			((flags & FILE_WRITE_RIGHTS) == FILE_WRITE_RIGHTS))
		*pmode |= (S_IWUGO & (*pbits_to_set));
	if ((flags & GENERIC_READ) ||
			((flags & FILE_READ_RIGHTS) == FILE_READ_RIGHTS))
		*pmode |= (S_IRUGO & (*pbits_to_set));
	if ((flags & GENERIC_EXECUTE) ||
			((flags & FILE_EXEC_RIGHTS) == FILE_EXEC_RIGHTS))
		*pmode |= (S_IXUGO & (*pbits_to_set));

	cFYI(DBG2, "access flags 0x%x mode now 0x%x", flags, *pmode);
	return;
}

/*
   Generate access flags to reflect permissions mode is the existing mode.
   This function is called for every ACE in the DACL whose SID matches
   with either owner or group or everyone.
*/

static void mode_to_access_flags(umode_t mode, umode_t bits_to_use,
				__u32 *pace_flags)
{
	/* reset access mask */
	*pace_flags = 0x0;

	/* bits to use are either S_IRWXU or S_IRWXG or S_IRWXO */
	mode &= bits_to_use;

	/* check for R/W/X UGO since we do not know whose flags
	   is this but we have cleared all the bits sans RWX for
	   either user or group or other as per bits_to_use */
	if (mode & S_IRUGO)
		*pace_flags |= SET_FILE_READ_RIGHTS;
	if (mode & S_IWUGO)
		*pace_flags |= SET_FILE_WRITE_RIGHTS;
	if (mode & S_IXUGO)
		*pace_flags |= SET_FILE_EXEC_RIGHTS;

	cFYI(DBG2, "mode: 0x%x, access flags now 0x%x", mode, *pace_flags);
	return;
}

static __u16 fill_ace_for_sid(struct cifs_ace *pntace,
			const struct cifs_sid *psid, __u64 nmode, umode_t bits)
{
	int i;
	__u16 size = 0;
	__u32 access_req = 0;

	pntace->type = ACCESS_ALLOWED;
	pntace->flags = 0x0;
	mode_to_access_flags(nmode, bits, &access_req);
	if (!access_req)
		access_req = SET_MINIMUM_RIGHTS;
	pntace->access_req = cpu_to_le32(access_req);

	pntace->sid.revision = psid->revision;
	pntace->sid.num_subauth = psid->num_subauth;
	for (i = 0; i < 6; i++)
		pntace->sid.authority[i] = psid->authority[i];
	for (i = 0; i < psid->num_subauth; i++)
		pntace->sid.sub_auth[i] = psid->sub_auth[i];

	size = 1 + 1 + 2 + 4 + 1 + 1 + 6 + (psid->num_subauth * 4);
	pntace->size = cpu_to_le16(size);

	return size;
}


#ifdef CONFIG_CIFS_DEBUG2
static void dump_ace(struct cifs_ace *pace, char *end_of_acl)
{
	int num_subauth;

	/* validate that we do not go past end of acl */

	if (le16_to_cpu(pace->size) < 16) {
		cERROR(1, "ACE too small %d", le16_to_cpu(pace->size));
		return;
	}

	if (end_of_acl < (char *)pace + le16_to_cpu(pace->size)) {
		cERROR(1, "ACL too small to parse ACE");
		return;
	}

	num_subauth = pace->sid.num_subauth;
	if (num_subauth) {
		int i;
		cFYI(1, "ACE revision %d num_auth %d type %d flags %d size %d",
			pace->sid.revision, pace->sid.num_subauth, pace->type,
			pace->flags, le16_to_cpu(pace->size));
		for (i = 0; i < num_subauth; ++i) {
			cFYI(1, "ACE sub_auth[%d]: 0x%x", i,
				le32_to_cpu(pace->sid.sub_auth[i]));
		}

		/* BB add length check to make sure that we do not have huge
			num auths and therefore go off the end */
	}

	return;
}
#endif


static void parse_dacl(struct cifs_acl *pdacl, char *end_of_acl,
		       struct cifs_sid *pownersid, struct cifs_sid *pgrpsid,
		       struct cifs_fattr *fattr)
{
	int i;
	int num_aces = 0;
	int acl_size;
	char *acl_base;
	struct cifs_ace **ppace;

	/* BB need to add parm so we can store the SID BB */

	if (!pdacl) {
		/* no DACL in the security descriptor, set
		   all the permissions for user/group/other */
		fattr->cf_mode |= S_IRWXUGO;
		return;
	}

	/* validate that we do not go past end of acl */
	if (end_of_acl < (char *)pdacl + le16_to_cpu(pdacl->size)) {
		cERROR(1, "ACL too small to parse DACL");
		return;
	}

	cFYI(DBG2, "DACL revision %d size %d num aces %d",
		le16_to_cpu(pdacl->revision), le16_to_cpu(pdacl->size),
		le32_to_cpu(pdacl->num_aces));

	/* reset rwx permissions for user/group/other.
	   Also, if num_aces is 0 i.e. DACL has no ACEs,
	   user/group/other have no permissions */
	fattr->cf_mode &= ~(S_IRWXUGO);

	acl_base = (char *)pdacl;
	acl_size = sizeof(struct cifs_acl);

	num_aces = le32_to_cpu(pdacl->num_aces);
	if (num_aces  > 0) {
		umode_t user_mask = S_IRWXU;
		umode_t group_mask = S_IRWXG;
		umode_t other_mask = S_IRWXO;

		ppace = kmalloc(num_aces * sizeof(struct cifs_ace *),
				GFP_KERNEL);

		for (i = 0; i < num_aces; ++i) {
			ppace[i] = (struct cifs_ace *) (acl_base + acl_size);
#ifdef CONFIG_CIFS_DEBUG2
			dump_ace(ppace[i], end_of_acl);
#endif
			if (compare_sids(&(ppace[i]->sid), pownersid))
				access_flags_to_mode(ppace[i]->access_req,
						     ppace[i]->type,
						     &fattr->cf_mode,
						     &user_mask);
			if (compare_sids(&(ppace[i]->sid), pgrpsid))
				access_flags_to_mode(ppace[i]->access_req,
						     ppace[i]->type,
						     &fattr->cf_mode,
						     &group_mask);
			if (compare_sids(&(ppace[i]->sid), &sid_everyone))
				access_flags_to_mode(ppace[i]->access_req,
						     ppace[i]->type,
						     &fattr->cf_mode,
						     &other_mask);

/*			memcpy((void *)(&(cifscred->aces[i])),
				(void *)ppace[i],
				sizeof(struct cifs_ace)); */

			acl_base = (char *)ppace[i];
			acl_size = le16_to_cpu(ppace[i]->size);
		}

		kfree(ppace);
	}

	return;
}


static int set_chmod_dacl(struct cifs_acl *pndacl, struct cifs_sid *pownersid,
			struct cifs_sid *pgrpsid, __u64 nmode)
{
	u16 size = 0;
	struct cifs_acl *pnndacl;

	pnndacl = (struct cifs_acl *)((char *)pndacl + sizeof(struct cifs_acl));

	size += fill_ace_for_sid((struct cifs_ace *) ((char *)pnndacl + size),
					pownersid, nmode, S_IRWXU);
	size += fill_ace_for_sid((struct cifs_ace *)((char *)pnndacl + size),
					pgrpsid, nmode, S_IRWXG);
	size += fill_ace_for_sid((struct cifs_ace *)((char *)pnndacl + size),
					 &sid_everyone, nmode, S_IRWXO);

	pndacl->size = cpu_to_le16(size + sizeof(struct cifs_acl));
	pndacl->num_aces = cpu_to_le32(3);

	return 0;
}


static int parse_sid(struct cifs_sid *psid, char *end_of_acl)
{
	/* BB need to add parm so we can store the SID BB */

	/* validate that we do not go past end of ACL - sid must be at least 8
	   bytes long (assuming no sub-auths - e.g. the null SID */
	if (end_of_acl < (char *)psid + 8) {
		cERROR(1, "ACL too small to parse SID %p", psid);
		return -EINVAL;
	}

	if (psid->num_subauth) {
#ifdef CONFIG_CIFS_DEBUG2
		int i;
		cFYI(1, "SID revision %d num_auth %d",
			psid->revision, psid->num_subauth);

		for (i = 0; i < psid->num_subauth; i++) {
			cFYI(1, "SID sub_auth[%d]: 0x%x ", i,
				le32_to_cpu(psid->sub_auth[i]));
		}

		/* BB add length check to make sure that we do not have huge
			num auths and therefore go off the end */
		cFYI(1, "RID 0x%x",
			le32_to_cpu(psid->sub_auth[psid->num_subauth-1]));
#endif
	}

	return 0;
}


/* Convert CIFS ACL to POSIX form */
static int parse_sec_desc(struct cifs_ntsd *pntsd, int acl_len,
			  struct cifs_fattr *fattr)
{
	int rc;
	struct cifs_sid *owner_sid_ptr, *group_sid_ptr;
	struct cifs_acl *dacl_ptr; /* no need for SACL ptr */
	char *end_of_acl = ((char *)pntsd) + acl_len;
	__u32 dacloffset;

	if (pntsd == NULL)
		return -EIO;

	owner_sid_ptr = (struct cifs_sid *)((char *)pntsd +
				le32_to_cpu(pntsd->osidoffset));
	group_sid_ptr = (struct cifs_sid *)((char *)pntsd +
				le32_to_cpu(pntsd->gsidoffset));
	dacloffset = le32_to_cpu(pntsd->dacloffset);
	dacl_ptr = (struct cifs_acl *)((char *)pntsd + dacloffset);
	cFYI(DBG2, "revision %d type 0x%x ooffset 0x%x goffset 0x%x "
		 "sacloffset 0x%x dacloffset 0x%x",
		 pntsd->revision, pntsd->type, le32_to_cpu(pntsd->osidoffset),
		 le32_to_cpu(pntsd->gsidoffset),
		 le32_to_cpu(pntsd->sacloffset), dacloffset);
/*	cifs_dump_mem("owner_sid: ", owner_sid_ptr, 64); */
	rc = parse_sid(owner_sid_ptr, end_of_acl);
	if (rc)
		return rc;

	rc = parse_sid(group_sid_ptr, end_of_acl);
	if (rc)
		return rc;

	if (dacloffset)
		parse_dacl(dacl_ptr, end_of_acl, owner_sid_ptr,
			   group_sid_ptr, fattr);
	else
		cFYI(1, "no ACL"); /* BB grant all or default perms? */

/*	cifscred->uid = owner_sid_ptr->rid;
	cifscred->gid = group_sid_ptr->rid;
	memcpy((void *)(&(cifscred->osid)), (void *)owner_sid_ptr,
			sizeof(struct cifs_sid));
	memcpy((void *)(&(cifscred->gsid)), (void *)group_sid_ptr,
			sizeof(struct cifs_sid)); */

	return 0;
}


/* Convert permission bits from mode to equivalent CIFS ACL */
static int build_sec_desc(struct cifs_ntsd *pntsd, struct cifs_ntsd *pnntsd,
				struct inode *inode, __u64 nmode)
{
	int rc = 0;
	__u32 dacloffset;
	__u32 ndacloffset;
	__u32 sidsoffset;
	struct cifs_sid *owner_sid_ptr, *group_sid_ptr;
	struct cifs_acl *dacl_ptr = NULL;  /* no need for SACL ptr */
	struct cifs_acl *ndacl_ptr = NULL; /* no need for SACL ptr */

	if ((inode == NULL) || (pntsd == NULL) || (pnntsd == NULL))
		return -EIO;

	owner_sid_ptr = (struct cifs_sid *)((char *)pntsd +
				le32_to_cpu(pntsd->osidoffset));
	group_sid_ptr = (struct cifs_sid *)((char *)pntsd +
				le32_to_cpu(pntsd->gsidoffset));

	dacloffset = le32_to_cpu(pntsd->dacloffset);
	dacl_ptr = (struct cifs_acl *)((char *)pntsd + dacloffset);

	ndacloffset = sizeof(struct cifs_ntsd);
	ndacl_ptr = (struct cifs_acl *)((char *)pnntsd + ndacloffset);
	ndacl_ptr->revision = dacl_ptr->revision;
	ndacl_ptr->size = 0;
	ndacl_ptr->num_aces = 0;

	rc = set_chmod_dacl(ndacl_ptr, owner_sid_ptr, group_sid_ptr, nmode);

	sidsoffset = ndacloffset + le16_to_cpu(ndacl_ptr->size);

	/* copy security descriptor control portion and owner and group sid */
	copy_sec_desc(pntsd, pnntsd, sidsoffset);

	return rc;
}

static struct cifs_ntsd *get_cifs_acl_by_fid(struct cifs_sb_info *cifs_sb,
		__u16 fid, u32 *pacllen)
{
	struct cifs_ntsd *pntsd = NULL;
	int xid, rc;
	struct tcon_link *tlink = cifs_sb_tlink(cifs_sb);

	if (IS_ERR(tlink))
		return NULL;

	xid = GetXid();
	rc = CIFSSMBGetCIFSACL(xid, tlink_tcon(tlink), fid, &pntsd, pacllen);
	FreeXid(xid);

	cifs_put_tlink(tlink);

	cFYI(1, "GetCIFSACL rc = %d ACL len %d", rc, *pacllen);
	return pntsd;
}

static struct cifs_ntsd *get_cifs_acl_by_path(struct cifs_sb_info *cifs_sb,
		const char *path, u32 *pacllen)
{
	struct cifs_ntsd *pntsd = NULL;
	int oplock = 0;
	int xid, rc;
	__u16 fid;
	struct cifsTconInfo *tcon;
	struct tcon_link *tlink = cifs_sb_tlink(cifs_sb);

	if (IS_ERR(tlink))
		return NULL;

	tcon = tlink_tcon(tlink);
	xid = GetXid();

	rc = CIFSSMBOpen(xid, tcon, path, FILE_OPEN, READ_CONTROL, 0,
			 &fid, &oplock, NULL, cifs_sb->local_nls,
			 cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
	if (rc) {
		cERROR(1, "Unable to open file to get ACL");
		goto out;
	}

	rc = CIFSSMBGetCIFSACL(xid, tcon, fid, &pntsd, pacllen);
	cFYI(1, "GetCIFSACL rc = %d ACL len %d", rc, *pacllen);

	CIFSSMBClose(xid, tcon, fid);
 out:
	cifs_put_tlink(tlink);
	FreeXid(xid);
	return pntsd;
}

/* Retrieve an ACL from the server */
static struct cifs_ntsd *get_cifs_acl(struct cifs_sb_info *cifs_sb,
				      struct inode *inode, const char *path,
				      u32 *pacllen)
{
	struct cifs_ntsd *pntsd = NULL;
	struct cifsFileInfo *open_file = NULL;

	if (inode)
		open_file = find_readable_file(CIFS_I(inode), true);
	if (!open_file)
		return get_cifs_acl_by_path(cifs_sb, path, pacllen);

	pntsd = get_cifs_acl_by_fid(cifs_sb, open_file->netfid, pacllen);
	cifsFileInfo_put(open_file);
	return pntsd;
}

static int set_cifs_acl_by_fid(struct cifs_sb_info *cifs_sb, __u16 fid,
		struct cifs_ntsd *pnntsd, u32 acllen)
{
	int xid, rc;
	struct tcon_link *tlink = cifs_sb_tlink(cifs_sb);

	if (IS_ERR(tlink))
		return PTR_ERR(tlink);

	xid = GetXid();
	rc = CIFSSMBSetCIFSACL(xid, tlink_tcon(tlink), fid, pnntsd, acllen);
	FreeXid(xid);
	cifs_put_tlink(tlink);

	cFYI(DBG2, "SetCIFSACL rc = %d", rc);
	return rc;
}

static int set_cifs_acl_by_path(struct cifs_sb_info *cifs_sb, const char *path,
		struct cifs_ntsd *pnntsd, u32 acllen)
{
	int oplock = 0;
	int xid, rc;
	__u16 fid;
	struct cifsTconInfo *tcon;
	struct tcon_link *tlink = cifs_sb_tlink(cifs_sb);

	if (IS_ERR(tlink))
		return PTR_ERR(tlink);

	tcon = tlink_tcon(tlink);
	xid = GetXid();

	rc = CIFSSMBOpen(xid, tcon, path, FILE_OPEN, WRITE_DAC, 0,
			 &fid, &oplock, NULL, cifs_sb->local_nls,
			 cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
	if (rc) {
		cERROR(1, "Unable to open file to set ACL");
		goto out;
	}

	rc = CIFSSMBSetCIFSACL(xid, tcon, fid, pnntsd, acllen);
	cFYI(DBG2, "SetCIFSACL rc = %d", rc);

	CIFSSMBClose(xid, tcon, fid);
out:
	FreeXid(xid);
	cifs_put_tlink(tlink);
	return rc;
}

/* Set an ACL on the server */
static int set_cifs_acl(struct cifs_ntsd *pnntsd, __u32 acllen,
				struct inode *inode, const char *path)
{
	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
	struct cifsFileInfo *open_file;
	int rc;

	cFYI(DBG2, "set ACL for %s from mode 0x%x", path, inode->i_mode);

	open_file = find_readable_file(CIFS_I(inode), true);
	if (!open_file)
		return set_cifs_acl_by_path(cifs_sb, path, pnntsd, acllen);

	rc = set_cifs_acl_by_fid(cifs_sb, open_file->netfid, pnntsd, acllen);
	cifsFileInfo_put(open_file);
	return rc;
}

/* Translate the CIFS ACL (simlar to NTFS ACL) for a file into mode bits */
void
cifs_acl_to_fattr(struct cifs_sb_info *cifs_sb, struct cifs_fattr *fattr,
		  struct inode *inode, const char *path, const __u16 *pfid)
{
	struct cifs_ntsd *pntsd = NULL;
	u32 acllen = 0;
	int rc = 0;

	cFYI(DBG2, "converting ACL to mode for %s", path);

	if (pfid)
		pntsd = get_cifs_acl_by_fid(cifs_sb, *pfid, &acllen);
	else
		pntsd = get_cifs_acl(cifs_sb, inode, path, &acllen);

	/* if we can retrieve the ACL, now parse Access Control Entries, ACEs */
	if (pntsd)
		rc = parse_sec_desc(pntsd, acllen, fattr);
	if (rc)
		cFYI(1, "parse sec desc failed rc = %d", rc);

	kfree(pntsd);
	return;
}

/* Convert mode bits to an ACL so we can update the ACL on the server */
int mode_to_acl(struct inode *inode, const char *path, __u64 nmode)
{
	int rc = 0;
	__u32 secdesclen = 0;
	struct cifs_ntsd *pntsd = NULL; /* acl obtained from server */
	struct cifs_ntsd *pnntsd = NULL; /* modified acl to be sent to server */

	cFYI(DBG2, "set ACL from mode for %s", path);

	/* Get the security descriptor */
	pntsd = get_cifs_acl(CIFS_SB(inode->i_sb), inode, path, &secdesclen);

	/* Add three ACEs for owner, group, everyone getting rid of
	   other ACEs as chmod disables ACEs and set the security descriptor */

	if (pntsd) {
		/* allocate memory for the smb header,
		   set security descriptor request security descriptor
		   parameters, and secuirty descriptor itself */

		secdesclen = secdesclen < DEFSECDESCLEN ?
					DEFSECDESCLEN : secdesclen;
		pnntsd = kmalloc(secdesclen, GFP_KERNEL);
		if (!pnntsd) {
			cERROR(1, "Unable to allocate security descriptor");
			kfree(pntsd);
			return -ENOMEM;
		}

		rc = build_sec_desc(pntsd, pnntsd, inode, nmode);

		cFYI(DBG2, "build_sec_desc rc: %d", rc);

		if (!rc) {
			/* Set the security descriptor */
			rc = set_cifs_acl(pnntsd, secdesclen, inode, path);
			cFYI(DBG2, "set_cifs_acl rc: %d", rc);
		}

		kfree(pnntsd);
		kfree(pntsd);
	}

	return rc;
}
#endif /* CONFIG_CIFS_EXPERIMENTAL */