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[linux-2.6.git] / fs / ext3 / acl.c
1 /*
2  * linux/fs/ext3/acl.c
3  *
4  * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
5  */
6
7 #include <linux/init.h>
8 #include <linux/sched.h>
9 #include <linux/slab.h>
10 #include <linux/capability.h>
11 #include <linux/fs.h>
12 #include <linux/ext3_jbd.h>
13 #include <linux/ext3_fs.h>
14 #include "xattr.h"
15 #include "acl.h"
16
17 /*
18  * Convert from filesystem to in-memory representation.
19  */
20 static struct posix_acl *
21 ext3_acl_from_disk(const void *value, size_t size)
22 {
23         const char *end = (char *)value + size;
24         int n, count;
25         struct posix_acl *acl;
26
27         if (!value)
28                 return NULL;
29         if (size < sizeof(ext3_acl_header))
30                  return ERR_PTR(-EINVAL);
31         if (((ext3_acl_header *)value)->a_version !=
32             cpu_to_le32(EXT3_ACL_VERSION))
33                 return ERR_PTR(-EINVAL);
34         value = (char *)value + sizeof(ext3_acl_header);
35         count = ext3_acl_count(size);
36         if (count < 0)
37                 return ERR_PTR(-EINVAL);
38         if (count == 0)
39                 return NULL;
40         acl = posix_acl_alloc(count, GFP_NOFS);
41         if (!acl)
42                 return ERR_PTR(-ENOMEM);
43         for (n=0; n < count; n++) {
44                 ext3_acl_entry *entry =
45                         (ext3_acl_entry *)value;
46                 if ((char *)value + sizeof(ext3_acl_entry_short) > end)
47                         goto fail;
48                 acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
49                 acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
50                 switch(acl->a_entries[n].e_tag) {
51                         case ACL_USER_OBJ:
52                         case ACL_GROUP_OBJ:
53                         case ACL_MASK:
54                         case ACL_OTHER:
55                                 value = (char *)value +
56                                         sizeof(ext3_acl_entry_short);
57                                 acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
58                                 break;
59
60                         case ACL_USER:
61                         case ACL_GROUP:
62                                 value = (char *)value + sizeof(ext3_acl_entry);
63                                 if ((char *)value > end)
64                                         goto fail;
65                                 acl->a_entries[n].e_id =
66                                         le32_to_cpu(entry->e_id);
67                                 break;
68
69                         default:
70                                 goto fail;
71                 }
72         }
73         if (value != end)
74                 goto fail;
75         return acl;
76
77 fail:
78         posix_acl_release(acl);
79         return ERR_PTR(-EINVAL);
80 }
81
82 /*
83  * Convert from in-memory to filesystem representation.
84  */
85 static void *
86 ext3_acl_to_disk(const struct posix_acl *acl, size_t *size)
87 {
88         ext3_acl_header *ext_acl;
89         char *e;
90         size_t n;
91
92         *size = ext3_acl_size(acl->a_count);
93         ext_acl = kmalloc(sizeof(ext3_acl_header) + acl->a_count *
94                         sizeof(ext3_acl_entry), GFP_NOFS);
95         if (!ext_acl)
96                 return ERR_PTR(-ENOMEM);
97         ext_acl->a_version = cpu_to_le32(EXT3_ACL_VERSION);
98         e = (char *)ext_acl + sizeof(ext3_acl_header);
99         for (n=0; n < acl->a_count; n++) {
100                 ext3_acl_entry *entry = (ext3_acl_entry *)e;
101                 entry->e_tag  = cpu_to_le16(acl->a_entries[n].e_tag);
102                 entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
103                 switch(acl->a_entries[n].e_tag) {
104                         case ACL_USER:
105                         case ACL_GROUP:
106                                 entry->e_id =
107                                         cpu_to_le32(acl->a_entries[n].e_id);
108                                 e += sizeof(ext3_acl_entry);
109                                 break;
110
111                         case ACL_USER_OBJ:
112                         case ACL_GROUP_OBJ:
113                         case ACL_MASK:
114                         case ACL_OTHER:
115                                 e += sizeof(ext3_acl_entry_short);
116                                 break;
117
118                         default:
119                                 goto fail;
120                 }
121         }
122         return (char *)ext_acl;
123
124 fail:
125         kfree(ext_acl);
126         return ERR_PTR(-EINVAL);
127 }
128
129 /*
130  * Inode operation get_posix_acl().
131  *
132  * inode->i_mutex: don't care
133  */
134 static struct posix_acl *
135 ext3_get_acl(struct inode *inode, int type)
136 {
137         int name_index;
138         char *value = NULL;
139         struct posix_acl *acl;
140         int retval;
141
142         if (!test_opt(inode->i_sb, POSIX_ACL))
143                 return NULL;
144
145         acl = get_cached_acl(inode, type);
146         if (acl != ACL_NOT_CACHED)
147                 return acl;
148
149         switch (type) {
150         case ACL_TYPE_ACCESS:
151                 name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
152                 break;
153         case ACL_TYPE_DEFAULT:
154                 name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
155                 break;
156         default:
157                 BUG();
158         }
159
160         retval = ext3_xattr_get(inode, name_index, "", NULL, 0);
161         if (retval > 0) {
162                 value = kmalloc(retval, GFP_NOFS);
163                 if (!value)
164                         return ERR_PTR(-ENOMEM);
165                 retval = ext3_xattr_get(inode, name_index, "", value, retval);
166         }
167         if (retval > 0)
168                 acl = ext3_acl_from_disk(value, retval);
169         else if (retval == -ENODATA || retval == -ENOSYS)
170                 acl = NULL;
171         else
172                 acl = ERR_PTR(retval);
173         kfree(value);
174
175         if (!IS_ERR(acl))
176                 set_cached_acl(inode, type, acl);
177
178         return acl;
179 }
180
181 /*
182  * Set the access or default ACL of an inode.
183  *
184  * inode->i_mutex: down unless called from ext3_new_inode
185  */
186 static int
187 ext3_set_acl(handle_t *handle, struct inode *inode, int type,
188              struct posix_acl *acl)
189 {
190         int name_index;
191         void *value = NULL;
192         size_t size = 0;
193         int error;
194
195         if (S_ISLNK(inode->i_mode))
196                 return -EOPNOTSUPP;
197
198         switch(type) {
199                 case ACL_TYPE_ACCESS:
200                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
201                         if (acl) {
202                                 mode_t mode = inode->i_mode;
203                                 error = posix_acl_equiv_mode(acl, &mode);
204                                 if (error < 0)
205                                         return error;
206                                 else {
207                                         inode->i_mode = mode;
208                                         ext3_mark_inode_dirty(handle, inode);
209                                         if (error == 0)
210                                                 acl = NULL;
211                                 }
212                         }
213                         break;
214
215                 case ACL_TYPE_DEFAULT:
216                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
217                         if (!S_ISDIR(inode->i_mode))
218                                 return acl ? -EACCES : 0;
219                         break;
220
221                 default:
222                         return -EINVAL;
223         }
224         if (acl) {
225                 value = ext3_acl_to_disk(acl, &size);
226                 if (IS_ERR(value))
227                         return (int)PTR_ERR(value);
228         }
229
230         error = ext3_xattr_set_handle(handle, inode, name_index, "",
231                                       value, size, 0);
232
233         kfree(value);
234
235         if (!error)
236                 set_cached_acl(inode, type, acl);
237
238         return error;
239 }
240
241 static int
242 ext3_check_acl(struct inode *inode, int mask)
243 {
244         struct posix_acl *acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
245
246         if (IS_ERR(acl))
247                 return PTR_ERR(acl);
248         if (acl) {
249                 int error = posix_acl_permission(inode, acl, mask);
250                 posix_acl_release(acl);
251                 return error;
252         }
253
254         return -EAGAIN;
255 }
256
257 int
258 ext3_permission(struct inode *inode, int mask)
259 {
260         return generic_permission(inode, mask, ext3_check_acl);
261 }
262
263 /*
264  * Initialize the ACLs of a new inode. Called from ext3_new_inode.
265  *
266  * dir->i_mutex: down
267  * inode->i_mutex: up (access to inode is still exclusive)
268  */
269 int
270 ext3_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
271 {
272         struct posix_acl *acl = NULL;
273         int error = 0;
274
275         if (!S_ISLNK(inode->i_mode)) {
276                 if (test_opt(dir->i_sb, POSIX_ACL)) {
277                         acl = ext3_get_acl(dir, ACL_TYPE_DEFAULT);
278                         if (IS_ERR(acl))
279                                 return PTR_ERR(acl);
280                 }
281                 if (!acl)
282                         inode->i_mode &= ~current_umask();
283         }
284         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
285                 struct posix_acl *clone;
286                 mode_t mode;
287
288                 if (S_ISDIR(inode->i_mode)) {
289                         error = ext3_set_acl(handle, inode,
290                                              ACL_TYPE_DEFAULT, acl);
291                         if (error)
292                                 goto cleanup;
293                 }
294                 clone = posix_acl_clone(acl, GFP_NOFS);
295                 error = -ENOMEM;
296                 if (!clone)
297                         goto cleanup;
298
299                 mode = inode->i_mode;
300                 error = posix_acl_create_masq(clone, &mode);
301                 if (error >= 0) {
302                         inode->i_mode = mode;
303                         if (error > 0) {
304                                 /* This is an extended ACL */
305                                 error = ext3_set_acl(handle, inode,
306                                                      ACL_TYPE_ACCESS, clone);
307                         }
308                 }
309                 posix_acl_release(clone);
310         }
311 cleanup:
312         posix_acl_release(acl);
313         return error;
314 }
315
316 /*
317  * Does chmod for an inode that may have an Access Control List. The
318  * inode->i_mode field must be updated to the desired value by the caller
319  * before calling this function.
320  * Returns 0 on success, or a negative error number.
321  *
322  * We change the ACL rather than storing some ACL entries in the file
323  * mode permission bits (which would be more efficient), because that
324  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
325  * for directories) are added. There are no more bits available in the
326  * file mode.
327  *
328  * inode->i_mutex: down
329  */
330 int
331 ext3_acl_chmod(struct inode *inode)
332 {
333         struct posix_acl *acl, *clone;
334         int error;
335
336         if (S_ISLNK(inode->i_mode))
337                 return -EOPNOTSUPP;
338         if (!test_opt(inode->i_sb, POSIX_ACL))
339                 return 0;
340         acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
341         if (IS_ERR(acl) || !acl)
342                 return PTR_ERR(acl);
343         clone = posix_acl_clone(acl, GFP_KERNEL);
344         posix_acl_release(acl);
345         if (!clone)
346                 return -ENOMEM;
347         error = posix_acl_chmod_masq(clone, inode->i_mode);
348         if (!error) {
349                 handle_t *handle;
350                 int retries = 0;
351
352         retry:
353                 handle = ext3_journal_start(inode,
354                                 EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
355                 if (IS_ERR(handle)) {
356                         error = PTR_ERR(handle);
357                         ext3_std_error(inode->i_sb, error);
358                         goto out;
359                 }
360                 error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, clone);
361                 ext3_journal_stop(handle);
362                 if (error == -ENOSPC &&
363                     ext3_should_retry_alloc(inode->i_sb, &retries))
364                         goto retry;
365         }
366 out:
367         posix_acl_release(clone);
368         return error;
369 }
370
371 /*
372  * Extended attribute handlers
373  */
374 static size_t
375 ext3_xattr_list_acl_access(struct inode *inode, char *list, size_t list_len,
376                            const char *name, size_t name_len)
377 {
378         const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
379
380         if (!test_opt(inode->i_sb, POSIX_ACL))
381                 return 0;
382         if (list && size <= list_len)
383                 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
384         return size;
385 }
386
387 static size_t
388 ext3_xattr_list_acl_default(struct inode *inode, char *list, size_t list_len,
389                             const char *name, size_t name_len)
390 {
391         const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
392
393         if (!test_opt(inode->i_sb, POSIX_ACL))
394                 return 0;
395         if (list && size <= list_len)
396                 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
397         return size;
398 }
399
400 static int
401 ext3_xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size)
402 {
403         struct posix_acl *acl;
404         int error;
405
406         if (!test_opt(inode->i_sb, POSIX_ACL))
407                 return -EOPNOTSUPP;
408
409         acl = ext3_get_acl(inode, type);
410         if (IS_ERR(acl))
411                 return PTR_ERR(acl);
412         if (acl == NULL)
413                 return -ENODATA;
414         error = posix_acl_to_xattr(acl, buffer, size);
415         posix_acl_release(acl);
416
417         return error;
418 }
419
420 static int
421 ext3_xattr_get_acl_access(struct inode *inode, const char *name,
422                           void *buffer, size_t size)
423 {
424         if (strcmp(name, "") != 0)
425                 return -EINVAL;
426         return ext3_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
427 }
428
429 static int
430 ext3_xattr_get_acl_default(struct inode *inode, const char *name,
431                            void *buffer, size_t size)
432 {
433         if (strcmp(name, "") != 0)
434                 return -EINVAL;
435         return ext3_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
436 }
437
438 static int
439 ext3_xattr_set_acl(struct inode *inode, int type, const void *value,
440                    size_t size)
441 {
442         handle_t *handle;
443         struct posix_acl *acl;
444         int error, retries = 0;
445
446         if (!test_opt(inode->i_sb, POSIX_ACL))
447                 return -EOPNOTSUPP;
448         if (!is_owner_or_cap(inode))
449                 return -EPERM;
450
451         if (value) {
452                 acl = posix_acl_from_xattr(value, size);
453                 if (IS_ERR(acl))
454                         return PTR_ERR(acl);
455                 else if (acl) {
456                         error = posix_acl_valid(acl);
457                         if (error)
458                                 goto release_and_out;
459                 }
460         } else
461                 acl = NULL;
462
463 retry:
464         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
465         if (IS_ERR(handle))
466                 return PTR_ERR(handle);
467         error = ext3_set_acl(handle, inode, type, acl);
468         ext3_journal_stop(handle);
469         if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
470                 goto retry;
471
472 release_and_out:
473         posix_acl_release(acl);
474         return error;
475 }
476
477 static int
478 ext3_xattr_set_acl_access(struct inode *inode, const char *name,
479                           const void *value, size_t size, int flags)
480 {
481         if (strcmp(name, "") != 0)
482                 return -EINVAL;
483         return ext3_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
484 }
485
486 static int
487 ext3_xattr_set_acl_default(struct inode *inode, const char *name,
488                            const void *value, size_t size, int flags)
489 {
490         if (strcmp(name, "") != 0)
491                 return -EINVAL;
492         return ext3_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
493 }
494
495 struct xattr_handler ext3_xattr_acl_access_handler = {
496         .prefix = POSIX_ACL_XATTR_ACCESS,
497         .list   = ext3_xattr_list_acl_access,
498         .get    = ext3_xattr_get_acl_access,
499         .set    = ext3_xattr_set_acl_access,
500 };
501
502 struct xattr_handler ext3_xattr_acl_default_handler = {
503         .prefix = POSIX_ACL_XATTR_DEFAULT,
504         .list   = ext3_xattr_list_acl_default,
505         .get    = ext3_xattr_get_acl_default,
506         .set    = ext3_xattr_set_acl_default,
507 };