aboutsummaryrefslogtreecommitdiffstats
path: root/fs/xfs/linux-2.6/xfs_acl.c
blob: 1e9d1246eebc8e946e508e1c24f070f5aa28c394 (plain) (blame)
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
/*
 * Copyright (c) 2008, Christoph Hellwig
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include "xfs.h"
#include "xfs_acl.h"
#include "xfs_attr.h"
#include "xfs_bmap_btree.h"
#include "xfs_inode.h"
#include "xfs_vnodeops.h"
#include <linux/xattr.h>
#include <linux/posix_acl_xattr.h>


#define XFS_ACL_NOT_CACHED	((void *)-1)

/*
 * Locking scheme:
 *  - all ACL updates are protected by inode->i_mutex, which is taken before
 *    calling into this file.
 *  - access and updates to the ip->i_acl and ip->i_default_acl pointers are
 *    protected by inode->i_lock.
 */

STATIC struct posix_acl *
xfs_acl_from_disk(struct xfs_acl *aclp)
{
	struct posix_acl_entry *acl_e;
	struct posix_acl *acl;
	struct xfs_acl_entry *ace;
	int count, i;

	count = be32_to_cpu(aclp->acl_cnt);

	acl = posix_acl_alloc(count, GFP_KERNEL);
	if (!acl)
		return ERR_PTR(-ENOMEM);

	for (i = 0; i < count; i++) {
		acl_e = &acl->a_entries[i];
		ace = &aclp->acl_entry[i];

		/*
		 * The tag is 32 bits on disk and 16 bits in core.
		 *
		 * Because every access to it goes through the core
		 * format first this is not a problem.
		 */
		acl_e->e_tag = be32_to_cpu(ace->ae_tag);
		acl_e->e_perm = be16_to_cpu(ace->ae_perm);

		switch (acl_e->e_tag) {
		case ACL_USER:
		case ACL_GROUP:
			acl_e->e_id = be32_to_cpu(ace->ae_id);
			break;
		case ACL_USER_OBJ:
		case ACL_GROUP_OBJ:
		case ACL_MASK:
		case ACL_OTHER:
			acl_e->e_id = ACL_UNDEFINED_ID;
			break;
		default:
			goto fail;
		}
	}
	return acl;

fail:
	posix_acl_release(acl);
	return ERR_PTR(-EINVAL);
}

STATIC void
xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl)
{
	const struct posix_acl_entry *acl_e;
	struct xfs_acl_entry *ace;
	int i;

	aclp->acl_cnt = cpu_to_be32(acl->a_count);
	for (i = 0; i < acl->a_count; i++) {
		ace = &aclp->acl_entry[i];
		acl_e = &acl->a_entries[i];

		ace->ae_tag = cpu_to_be32(acl_e->e_tag);
		ace->ae_id = cpu_to_be32(acl_e->e_id);
		ace->ae_perm = cpu_to_be16(acl_e->e_perm);
	}
}

/*
 * Update the cached ACL pointer in the inode.
 *
 * Because we don't hold any locks while reading/writing the attribute
 * from/to disk another thread could have raced and updated the cached
 * ACL value before us. In that case we release the previous cached value
 * and update it with our new value.
 */
STATIC void
xfs_update_cached_acl(struct inode *inode, struct posix_acl **p_acl,
		struct posix_acl *acl)
{
	spin_lock(&inode->i_lock);
	if (*p_acl && *p_acl != XFS_ACL_NOT_CACHED)
		posix_acl_release(*p_acl);
	*p_acl = posix_acl_dup(acl);
	spin_unlock(&inode->i_lock);
}

struct posix_acl *
xfs_get_acl(struct inode *inode, int type)
{
	struct xfs_inode *ip = XFS_I(inode);
	struct posix_acl *acl = NULL, **p_acl;
	struct xfs_acl *xfs_acl;
	int len = sizeof(struct xfs_acl);
	char *ea_name;
	int error;

	switch (type) {
	case ACL_TYPE_ACCESS:
		ea_name = SGI_ACL_FILE;
		p_acl = &ip->i_acl;
		break;
	case ACL_TYPE_DEFAULT:
		ea_name = SGI_ACL_DEFAULT;
		p_acl = &ip->i_default_acl;
		break;
	default:
		return ERR_PTR(-EINVAL);
	}

	spin_lock(&inode->i_lock);
	if (*p_acl != XFS_ACL_NOT_CACHED)
		acl = posix_acl_dup(*p_acl);
	spin_unlock(&inode->i_lock);

	/*
	 * If we have a cached ACLs value just return it, not need to
	 * go out to the disk.
	 */
	if (acl)
		return acl;

	xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL);
	if (!xfs_acl)
		return ERR_PTR(-ENOMEM);

	error = -xfs_attr_get(ip, ea_name, (char *)xfs_acl, &len, ATTR_ROOT);
	if (error) {
		/*
		 * If the attribute doesn't exist make sure we have a negative
		 * cache entry, for any other error assume it is transient and
		 * leave the cache entry as XFS_ACL_NOT_CACHED.
		 */
		if (error == -ENOATTR) {
			acl = NULL;
			goto out_update_cache;
		}
		goto out;
	}

	acl = xfs_acl_from_disk(xfs_acl);
	if (IS_ERR(acl))
		goto out;

 out_update_cache:
	xfs_update_cached_acl(inode, p_acl, acl);
 out:
	kfree(xfs_acl);
	return acl;
}

STATIC int
xfs_set_acl(struct inode *inode, int type, struct posix_acl *acl)
{
	struct xfs_inode *ip = XFS_I(inode);
	struct posix_acl **p_acl;
	char *ea_name;
	int error;

	if (S_ISLNK(inode->i_mode))
		return -EOPNOTSUPP;

	switch (type) {
	case ACL_TYPE_ACCESS:
		ea_name = SGI_ACL_FILE;
		p_acl = &ip->i_acl;
		break;
	case ACL_TYPE_DEFAULT:
		if (!S_ISDIR(inode->i_mode))
			return acl ? -EACCES : 0;
		ea_name = SGI_ACL_DEFAULT;
		p_acl = &ip->i_default_acl;
		break;
	default:
		return -EINVAL;
	}

	if (acl) {
		struct xfs_acl *xfs_acl;
		int len;

		xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL);
		if (!xfs_acl)
			return -ENOMEM;

		xfs_acl_to_disk(xfs_acl, acl);
		len = sizeof(struct xfs_acl) -
			(sizeof(struct xfs_acl_entry) *
			 (XFS_ACL_MAX_ENTRIES - acl->a_count));

		error = -xfs_attr_set(ip, ea_name, (char *)xfs_acl,
				len, ATTR_ROOT);

		kfree(xfs_acl);
	} else {
		/*
		 * A NULL ACL argument means we want to remove the ACL.
		 */
		error = -xfs_attr_remove(ip, ea_name, ATTR_ROOT);

		/*
		 * If the attribute didn't exist to start with that's fine.
		 */
		if (error == -ENOATTR)
			error = 0;
	}

	if (!error)
		xfs_update_cached_acl(inode, p_acl, acl);
	return error;
}

int
xfs_check_acl(struct inode *inode, int mask)
{
	struct xfs_inode *ip = XFS_I(inode);
	struct posix_acl *acl;
	int error = -EAGAIN;

	xfs_itrace_entry(ip);

	/*
	 * If there is no attribute fork no ACL exists on this inode and
	 * we can skip the whole exercise.
	 */
	if (!XFS_IFORK_Q(ip))
		return -EAGAIN;

	acl = xfs_get_acl(inode, ACL_TYPE_ACCESS);
	if (IS_ERR(acl))
		return PTR_ERR(acl);
	if (acl) {
		error = posix_acl_permission(inode, acl, mask);
		posix_acl_release(acl);
	}

	return error;
}

static int
xfs_set_mode(struct inode *inode, mode_t mode)
{
	int error = 0;

	if (mode != inode->i_mode) {
		struct iattr iattr;

		iattr.ia_valid = ATTR_MODE;
		iattr.ia_mode = mode;

		error = -xfs_setattr(XFS_I(inode), &iattr, XFS_ATTR_NOACL);
	}

	return error;
}

static int
xfs_acl_exists(struct inode *inode, char *name)
{
	int len = sizeof(struct xfs_acl);

	return (xfs_attr_get(XFS_I(inode), name, NULL, &len,
			    ATTR_ROOT|ATTR_KERNOVAL) == 0);
}

int
posix_acl_access_exists(struct inode *inode)
{
	return xfs_acl_exists(inode, SGI_ACL_FILE);
}

int
posix_acl_default_exists(struct inode *inode)
{
	if (!S_ISDIR(inode->i_mode))
		return 0;
	return xfs_acl_exists(inode, SGI_ACL_DEFAULT);
}

/*
 * No need for i_mutex because the inode is not yet exposed to the VFS.
 */
int
xfs_inherit_acl(struct inode *inode, struct posix_acl *default_acl)
{
	struct posix_acl *clone;
	mode_t mode;
	int error = 0, inherit = 0;

	if (S_ISDIR(inode->i_mode)) {
		error = xfs_set_acl(inode, ACL_TYPE_DEFAULT, default_acl);
		if (error)
			return error;
	}

	clone = posix_acl_clone(default_acl, GFP_KERNEL);
	if (!clone)
		return -ENOMEM;

	mode = inode->i_mode;
	error = posix_acl_create_masq(clone, &mode);
	if (error < 0)
		goto out_release_clone;

	/*
	 * If posix_acl_create_masq returns a positive value we need to
	 * inherit a permission that can't be represented using the Unix
	 * mode bits and we actually need to set an ACL.
	 */
	if (error > 0)
		inherit = 1;

	error = xfs_set_mode(inode, mode);
	if (error)
		goto out_release_clone;

	if (inherit)
		error = xfs_set_acl(inode, ACL_TYPE_ACCESS, clone);

 out_release_clone:
	posix_acl_release(clone);
	return error;
}

int
xfs_acl_chmod(struct inode *inode)
{
	struct posix_acl *acl, *clone;
	int error;

	if (S_ISLNK(inode->i_mode))
		return -EOPNOTSUPP;

	acl = xfs_get_acl(inode, ACL_TYPE_ACCESS);
	if (IS_ERR(acl) || !acl)
		return PTR_ERR(acl);

	clone = posix_acl_clone(acl, GFP_KERNEL);
	posix_acl_release(acl);
	if (!clone)
		return -ENOMEM;

	error = posix_acl_chmod_masq(clone, inode->i_mode);
	if (!error)
		error = xfs_set_acl(inode, ACL_TYPE_ACCESS, clone);

	posix_acl_release(clone);
	return error;
}

void
xfs_inode_init_acls(struct xfs_inode *ip)
{
	/*
	 * No need for locking, inode is not live yet.
	 */
	ip->i_acl = XFS_ACL_NOT_CACHED;
	ip->i_default_acl = XFS_ACL_NOT_CACHED;
}

void
xfs_inode_clear_acls(struct xfs_inode *ip)
{
	/*
	 * No need for locking here, the inode is not live anymore
	 * and just about to be freed.
	 */
	if (ip->i_acl != XFS_ACL_NOT_CACHED)
		posix_acl_release(ip->i_acl);
	if (ip->i_default_acl != XFS_ACL_NOT_CACHED)
		posix_acl_release(ip->i_default_acl);
}


/*
 * System xattr handlers.
 *
 * Currently Posix ACLs are the only system namespace extended attribute
 * handlers supported by XFS, so we just implement the handlers here.
 * If we ever support other system extended attributes this will need
 * some refactoring.
 */

static int
xfs_decode_acl(const char *name)
{
	if (strcmp(name, "posix_acl_access") == 0)
		return ACL_TYPE_ACCESS;
	else if (strcmp(name, "posix_acl_default") == 0)
		return ACL_TYPE_DEFAULT;
	return -EINVAL;
}

static int
xfs_xattr_system_get(struct inode *inode, const char *name,
		void *value, size_t size)
{
	struct posix_acl *acl;
	int type, error;

	type = xfs_decode_acl(name);
	if (type < 0)
		return type;

	acl = xfs_get_acl(inode, type);
	if (IS_ERR(acl))
		return PTR_ERR(acl);
	if (acl == NULL)
		return -ENODATA;

	error = posix_acl_to_xattr(acl, value, size);
	posix_acl_release(acl);

	return error;
}

static int
xfs_xattr_system_set(struct inode *inode, const char *name,
		const void *value, size_t size, int flags)
{
	struct posix_acl *acl = NULL;
	int error = 0, type;

	type = xfs_decode_acl(name);
	if (type < 0)
		return type;
	if (flags & XATTR_CREATE)
		return -EINVAL;
	if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
		return value ? -EACCES : 0;
	if ((current_fsuid() != inode->i_uid) && !capable(CAP_FOWNER))
		return -EPERM;

	if (!value)
		goto set_acl;

	acl = posix_acl_from_xattr(value, size);
	if (!acl) {
		/*
		 * acl_set_file(3) may request that we set default ACLs with
		 * zero length -- defend (gracefully) against that here.
		 */
		goto out;
	}
	if (IS_ERR(acl)) {
		error = PTR_ERR(acl);
		goto out;
	}

	error = posix_acl_valid(acl);
	if (error)
		goto out_release;

	error = -EINVAL;
	if (acl->a_count > XFS_ACL_MAX_ENTRIES)
		goto out_release;

	if (type == ACL_TYPE_ACCESS) {
		mode_t mode = inode->i_mode;
		error = posix_acl_equiv_mode(acl, &mode);

		if (error <= 0) {
			posix_acl_release(acl);
			acl = NULL;

			if (error < 0)
				return error;
		}

		error = xfs_set_mode(inode, mode);
		if (error)
			goto out_release;
	}

 set_acl:
	error = xfs_set_acl(inode, type, acl);
 out_release:
	posix_acl_release(acl);
 out:
	return error;
}

struct xattr_handler xfs_xattr_system_handler = {
	.prefix	= XATTR_SYSTEM_PREFIX,
	.get	= xfs_xattr_system_get,
	.set	= xfs_xattr_system_set,
};