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Diffstat (limited to 'fs/xfs/linux-2.6/xfs_acl.c')
-rw-r--r--fs/xfs/linux-2.6/xfs_acl.c523
1 files changed, 523 insertions, 0 deletions
diff --git a/fs/xfs/linux-2.6/xfs_acl.c b/fs/xfs/linux-2.6/xfs_acl.c
new file mode 100644
index 000000000000..1e9d1246eebc
--- /dev/null
+++ b/fs/xfs/linux-2.6/xfs_acl.c
@@ -0,0 +1,523 @@
1/*
2 * Copyright (c) 2008, Christoph Hellwig
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_acl.h"
20#include "xfs_attr.h"
21#include "xfs_bmap_btree.h"
22#include "xfs_inode.h"
23#include "xfs_vnodeops.h"
24#include <linux/xattr.h>
25#include <linux/posix_acl_xattr.h>
26
27
28#define XFS_ACL_NOT_CACHED ((void *)-1)
29
30/*
31 * Locking scheme:
32 * - all ACL updates are protected by inode->i_mutex, which is taken before
33 * calling into this file.
34 * - access and updates to the ip->i_acl and ip->i_default_acl pointers are
35 * protected by inode->i_lock.
36 */
37
38STATIC struct posix_acl *
39xfs_acl_from_disk(struct xfs_acl *aclp)
40{
41 struct posix_acl_entry *acl_e;
42 struct posix_acl *acl;
43 struct xfs_acl_entry *ace;
44 int count, i;
45
46 count = be32_to_cpu(aclp->acl_cnt);
47
48 acl = posix_acl_alloc(count, GFP_KERNEL);
49 if (!acl)
50 return ERR_PTR(-ENOMEM);
51
52 for (i = 0; i < count; i++) {
53 acl_e = &acl->a_entries[i];
54 ace = &aclp->acl_entry[i];
55
56 /*
57 * The tag is 32 bits on disk and 16 bits in core.
58 *
59 * Because every access to it goes through the core
60 * format first this is not a problem.
61 */
62 acl_e->e_tag = be32_to_cpu(ace->ae_tag);
63 acl_e->e_perm = be16_to_cpu(ace->ae_perm);
64
65 switch (acl_e->e_tag) {
66 case ACL_USER:
67 case ACL_GROUP:
68 acl_e->e_id = be32_to_cpu(ace->ae_id);
69 break;
70 case ACL_USER_OBJ:
71 case ACL_GROUP_OBJ:
72 case ACL_MASK:
73 case ACL_OTHER:
74 acl_e->e_id = ACL_UNDEFINED_ID;
75 break;
76 default:
77 goto fail;
78 }
79 }
80 return acl;
81
82fail:
83 posix_acl_release(acl);
84 return ERR_PTR(-EINVAL);
85}
86
87STATIC void
88xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl)
89{
90 const struct posix_acl_entry *acl_e;
91 struct xfs_acl_entry *ace;
92 int i;
93
94 aclp->acl_cnt = cpu_to_be32(acl->a_count);
95 for (i = 0; i < acl->a_count; i++) {
96 ace = &aclp->acl_entry[i];
97 acl_e = &acl->a_entries[i];
98
99 ace->ae_tag = cpu_to_be32(acl_e->e_tag);
100 ace->ae_id = cpu_to_be32(acl_e->e_id);
101 ace->ae_perm = cpu_to_be16(acl_e->e_perm);
102 }
103}
104
105/*
106 * Update the cached ACL pointer in the inode.
107 *
108 * Because we don't hold any locks while reading/writing the attribute
109 * from/to disk another thread could have raced and updated the cached
110 * ACL value before us. In that case we release the previous cached value
111 * and update it with our new value.
112 */
113STATIC void
114xfs_update_cached_acl(struct inode *inode, struct posix_acl **p_acl,
115 struct posix_acl *acl)
116{
117 spin_lock(&inode->i_lock);
118 if (*p_acl && *p_acl != XFS_ACL_NOT_CACHED)
119 posix_acl_release(*p_acl);
120 *p_acl = posix_acl_dup(acl);
121 spin_unlock(&inode->i_lock);
122}
123
124struct posix_acl *
125xfs_get_acl(struct inode *inode, int type)
126{
127 struct xfs_inode *ip = XFS_I(inode);
128 struct posix_acl *acl = NULL, **p_acl;
129 struct xfs_acl *xfs_acl;
130 int len = sizeof(struct xfs_acl);
131 char *ea_name;
132 int error;
133
134 switch (type) {
135 case ACL_TYPE_ACCESS:
136 ea_name = SGI_ACL_FILE;
137 p_acl = &ip->i_acl;
138 break;
139 case ACL_TYPE_DEFAULT:
140 ea_name = SGI_ACL_DEFAULT;
141 p_acl = &ip->i_default_acl;
142 break;
143 default:
144 return ERR_PTR(-EINVAL);
145 }
146
147 spin_lock(&inode->i_lock);
148 if (*p_acl != XFS_ACL_NOT_CACHED)
149 acl = posix_acl_dup(*p_acl);
150 spin_unlock(&inode->i_lock);
151
152 /*
153 * If we have a cached ACLs value just return it, not need to
154 * go out to the disk.
155 */
156 if (acl)
157 return acl;
158
159 xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL);
160 if (!xfs_acl)
161 return ERR_PTR(-ENOMEM);
162
163 error = -xfs_attr_get(ip, ea_name, (char *)xfs_acl, &len, ATTR_ROOT);
164 if (error) {
165 /*
166 * If the attribute doesn't exist make sure we have a negative
167 * cache entry, for any other error assume it is transient and
168 * leave the cache entry as XFS_ACL_NOT_CACHED.
169 */
170 if (error == -ENOATTR) {
171 acl = NULL;
172 goto out_update_cache;
173 }
174 goto out;
175 }
176
177 acl = xfs_acl_from_disk(xfs_acl);
178 if (IS_ERR(acl))
179 goto out;
180
181 out_update_cache:
182 xfs_update_cached_acl(inode, p_acl, acl);
183 out:
184 kfree(xfs_acl);
185 return acl;
186}
187
188STATIC int
189xfs_set_acl(struct inode *inode, int type, struct posix_acl *acl)
190{
191 struct xfs_inode *ip = XFS_I(inode);
192 struct posix_acl **p_acl;
193 char *ea_name;
194 int error;
195
196 if (S_ISLNK(inode->i_mode))
197 return -EOPNOTSUPP;
198
199 switch (type) {
200 case ACL_TYPE_ACCESS:
201 ea_name = SGI_ACL_FILE;
202 p_acl = &ip->i_acl;
203 break;
204 case ACL_TYPE_DEFAULT:
205 if (!S_ISDIR(inode->i_mode))
206 return acl ? -EACCES : 0;
207 ea_name = SGI_ACL_DEFAULT;
208 p_acl = &ip->i_default_acl;
209 break;
210 default:
211 return -EINVAL;
212 }
213
214 if (acl) {
215 struct xfs_acl *xfs_acl;
216 int len;
217
218 xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL);
219 if (!xfs_acl)
220 return -ENOMEM;
221
222 xfs_acl_to_disk(xfs_acl, acl);
223 len = sizeof(struct xfs_acl) -
224 (sizeof(struct xfs_acl_entry) *
225 (XFS_ACL_MAX_ENTRIES - acl->a_count));
226
227 error = -xfs_attr_set(ip, ea_name, (char *)xfs_acl,
228 len, ATTR_ROOT);
229
230 kfree(xfs_acl);
231 } else {
232 /*
233 * A NULL ACL argument means we want to remove the ACL.
234 */
235 error = -xfs_attr_remove(ip, ea_name, ATTR_ROOT);
236
237 /*
238 * If the attribute didn't exist to start with that's fine.
239 */
240 if (error == -ENOATTR)
241 error = 0;
242 }
243
244 if (!error)
245 xfs_update_cached_acl(inode, p_acl, acl);
246 return error;
247}
248
249int
250xfs_check_acl(struct inode *inode, int mask)
251{
252 struct xfs_inode *ip = XFS_I(inode);
253 struct posix_acl *acl;
254 int error = -EAGAIN;
255
256 xfs_itrace_entry(ip);
257
258 /*
259 * If there is no attribute fork no ACL exists on this inode and
260 * we can skip the whole exercise.
261 */
262 if (!XFS_IFORK_Q(ip))
263 return -EAGAIN;
264
265 acl = xfs_get_acl(inode, ACL_TYPE_ACCESS);
266 if (IS_ERR(acl))
267 return PTR_ERR(acl);
268 if (acl) {
269 error = posix_acl_permission(inode, acl, mask);
270 posix_acl_release(acl);
271 }
272
273 return error;
274}
275
276static int
277xfs_set_mode(struct inode *inode, mode_t mode)
278{
279 int error = 0;
280
281 if (mode != inode->i_mode) {
282 struct iattr iattr;
283
284 iattr.ia_valid = ATTR_MODE;
285 iattr.ia_mode = mode;
286
287 error = -xfs_setattr(XFS_I(inode), &iattr, XFS_ATTR_NOACL);
288 }
289
290 return error;
291}
292
293static int
294xfs_acl_exists(struct inode *inode, char *name)
295{
296 int len = sizeof(struct xfs_acl);
297
298 return (xfs_attr_get(XFS_I(inode), name, NULL, &len,
299 ATTR_ROOT|ATTR_KERNOVAL) == 0);
300}
301
302int
303posix_acl_access_exists(struct inode *inode)
304{
305 return xfs_acl_exists(inode, SGI_ACL_FILE);
306}
307
308int
309posix_acl_default_exists(struct inode *inode)
310{
311 if (!S_ISDIR(inode->i_mode))
312 return 0;
313 return xfs_acl_exists(inode, SGI_ACL_DEFAULT);
314}
315
316/*
317 * No need for i_mutex because the inode is not yet exposed to the VFS.
318 */
319int
320xfs_inherit_acl(struct inode *inode, struct posix_acl *default_acl)
321{
322 struct posix_acl *clone;
323 mode_t mode;
324 int error = 0, inherit = 0;
325
326 if (S_ISDIR(inode->i_mode)) {
327 error = xfs_set_acl(inode, ACL_TYPE_DEFAULT, default_acl);
328 if (error)
329 return error;
330 }
331
332 clone = posix_acl_clone(default_acl, GFP_KERNEL);
333 if (!clone)
334 return -ENOMEM;
335
336 mode = inode->i_mode;
337 error = posix_acl_create_masq(clone, &mode);
338 if (error < 0)
339 goto out_release_clone;
340
341 /*
342 * If posix_acl_create_masq returns a positive value we need to
343 * inherit a permission that can't be represented using the Unix
344 * mode bits and we actually need to set an ACL.
345 */
346 if (error > 0)
347 inherit = 1;
348
349 error = xfs_set_mode(inode, mode);
350 if (error)
351 goto out_release_clone;
352
353 if (inherit)
354 error = xfs_set_acl(inode, ACL_TYPE_ACCESS, clone);
355
356 out_release_clone:
357 posix_acl_release(clone);
358 return error;
359}
360
361int
362xfs_acl_chmod(struct inode *inode)
363{
364 struct posix_acl *acl, *clone;
365 int error;
366
367 if (S_ISLNK(inode->i_mode))
368 return -EOPNOTSUPP;
369
370 acl = xfs_get_acl(inode, ACL_TYPE_ACCESS);
371 if (IS_ERR(acl) || !acl)
372 return PTR_ERR(acl);
373
374 clone = posix_acl_clone(acl, GFP_KERNEL);
375 posix_acl_release(acl);
376 if (!clone)
377 return -ENOMEM;
378
379 error = posix_acl_chmod_masq(clone, inode->i_mode);
380 if (!error)
381 error = xfs_set_acl(inode, ACL_TYPE_ACCESS, clone);
382
383 posix_acl_release(clone);
384 return error;
385}
386
387void
388xfs_inode_init_acls(struct xfs_inode *ip)
389{
390 /*
391 * No need for locking, inode is not live yet.
392 */
393 ip->i_acl = XFS_ACL_NOT_CACHED;
394 ip->i_default_acl = XFS_ACL_NOT_CACHED;
395}
396
397void
398xfs_inode_clear_acls(struct xfs_inode *ip)
399{
400 /*
401 * No need for locking here, the inode is not live anymore
402 * and just about to be freed.
403 */
404 if (ip->i_acl != XFS_ACL_NOT_CACHED)
405 posix_acl_release(ip->i_acl);
406 if (ip->i_default_acl != XFS_ACL_NOT_CACHED)
407 posix_acl_release(ip->i_default_acl);
408}
409
410
411/*
412 * System xattr handlers.
413 *
414 * Currently Posix ACLs are the only system namespace extended attribute
415 * handlers supported by XFS, so we just implement the handlers here.
416 * If we ever support other system extended attributes this will need
417 * some refactoring.
418 */
419
420static int
421xfs_decode_acl(const char *name)
422{
423 if (strcmp(name, "posix_acl_access") == 0)
424 return ACL_TYPE_ACCESS;
425 else if (strcmp(name, "posix_acl_default") == 0)
426 return ACL_TYPE_DEFAULT;
427 return -EINVAL;
428}
429
430static int
431xfs_xattr_system_get(struct inode *inode, const char *name,
432 void *value, size_t size)
433{
434 struct posix_acl *acl;
435 int type, error;
436
437 type = xfs_decode_acl(name);
438 if (type < 0)
439 return type;
440
441 acl = xfs_get_acl(inode, type);
442 if (IS_ERR(acl))
443 return PTR_ERR(acl);
444 if (acl == NULL)
445 return -ENODATA;
446
447 error = posix_acl_to_xattr(acl, value, size);
448 posix_acl_release(acl);
449
450 return error;
451}
452
453static int
454xfs_xattr_system_set(struct inode *inode, const char *name,
455 const void *value, size_t size, int flags)
456{
457 struct posix_acl *acl = NULL;
458 int error = 0, type;
459
460 type = xfs_decode_acl(name);
461 if (type < 0)
462 return type;
463 if (flags & XATTR_CREATE)
464 return -EINVAL;
465 if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
466 return value ? -EACCES : 0;
467 if ((current_fsuid() != inode->i_uid) && !capable(CAP_FOWNER))
468 return -EPERM;
469
470 if (!value)
471 goto set_acl;
472
473 acl = posix_acl_from_xattr(value, size);
474 if (!acl) {
475 /*
476 * acl_set_file(3) may request that we set default ACLs with
477 * zero length -- defend (gracefully) against that here.
478 */
479 goto out;
480 }
481 if (IS_ERR(acl)) {
482 error = PTR_ERR(acl);
483 goto out;
484 }
485
486 error = posix_acl_valid(acl);
487 if (error)
488 goto out_release;
489
490 error = -EINVAL;
491 if (acl->a_count > XFS_ACL_MAX_ENTRIES)
492 goto out_release;
493
494 if (type == ACL_TYPE_ACCESS) {
495 mode_t mode = inode->i_mode;
496 error = posix_acl_equiv_mode(acl, &mode);
497
498 if (error <= 0) {
499 posix_acl_release(acl);
500 acl = NULL;
501
502 if (error < 0)
503 return error;
504 }
505
506 error = xfs_set_mode(inode, mode);
507 if (error)
508 goto out_release;
509 }
510
511 set_acl:
512 error = xfs_set_acl(inode, type, acl);
513 out_release:
514 posix_acl_release(acl);
515 out:
516 return error;
517}
518
519struct xattr_handler xfs_xattr_system_handler = {
520 .prefix = XATTR_SYSTEM_PREFIX,
521 .get = xfs_xattr_system_get,
522 .set = xfs_xattr_system_set,
523};