kill boilerplate around posix_acl_chmod_masq()
[linux-2.6.git] / fs / ext4 / acl.c
1 /*
2  * linux/fs/ext4/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 "ext4_jbd2.h"
13 #include "ext4.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 ext4_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(ext4_acl_header))
30                  return ERR_PTR(-EINVAL);
31         if (((ext4_acl_header *)value)->a_version !=
32             cpu_to_le32(EXT4_ACL_VERSION))
33                 return ERR_PTR(-EINVAL);
34         value = (char *)value + sizeof(ext4_acl_header);
35         count = ext4_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                 ext4_acl_entry *entry =
45                         (ext4_acl_entry *)value;
46                 if ((char *)value + sizeof(ext4_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
51                 switch (acl->a_entries[n].e_tag) {
52                 case ACL_USER_OBJ:
53                 case ACL_GROUP_OBJ:
54                 case ACL_MASK:
55                 case ACL_OTHER:
56                         value = (char *)value +
57                                 sizeof(ext4_acl_entry_short);
58                         acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
59                         break;
60
61                 case ACL_USER:
62                 case ACL_GROUP:
63                         value = (char *)value + sizeof(ext4_acl_entry);
64                         if ((char *)value > end)
65                                 goto fail;
66                         acl->a_entries[n].e_id =
67                                 le32_to_cpu(entry->e_id);
68                         break;
69
70                 default:
71                         goto fail;
72                 }
73         }
74         if (value != end)
75                 goto fail;
76         return acl;
77
78 fail:
79         posix_acl_release(acl);
80         return ERR_PTR(-EINVAL);
81 }
82
83 /*
84  * Convert from in-memory to filesystem representation.
85  */
86 static void *
87 ext4_acl_to_disk(const struct posix_acl *acl, size_t *size)
88 {
89         ext4_acl_header *ext_acl;
90         char *e;
91         size_t n;
92
93         *size = ext4_acl_size(acl->a_count);
94         ext_acl = kmalloc(sizeof(ext4_acl_header) + acl->a_count *
95                         sizeof(ext4_acl_entry), GFP_NOFS);
96         if (!ext_acl)
97                 return ERR_PTR(-ENOMEM);
98         ext_acl->a_version = cpu_to_le32(EXT4_ACL_VERSION);
99         e = (char *)ext_acl + sizeof(ext4_acl_header);
100         for (n = 0; n < acl->a_count; n++) {
101                 ext4_acl_entry *entry = (ext4_acl_entry *)e;
102                 entry->e_tag  = cpu_to_le16(acl->a_entries[n].e_tag);
103                 entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
104                 switch (acl->a_entries[n].e_tag) {
105                 case ACL_USER:
106                 case ACL_GROUP:
107                         entry->e_id = cpu_to_le32(acl->a_entries[n].e_id);
108                         e += sizeof(ext4_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(ext4_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 ext4_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 = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
152                 break;
153         case ACL_TYPE_DEFAULT:
154                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
155                 break;
156         default:
157                 BUG();
158         }
159         retval = ext4_xattr_get(inode, name_index, "", NULL, 0);
160         if (retval > 0) {
161                 value = kmalloc(retval, GFP_NOFS);
162                 if (!value)
163                         return ERR_PTR(-ENOMEM);
164                 retval = ext4_xattr_get(inode, name_index, "", value, retval);
165         }
166         if (retval > 0)
167                 acl = ext4_acl_from_disk(value, retval);
168         else if (retval == -ENODATA || retval == -ENOSYS)
169                 acl = NULL;
170         else
171                 acl = ERR_PTR(retval);
172         kfree(value);
173
174         if (!IS_ERR(acl))
175                 set_cached_acl(inode, type, acl);
176
177         return acl;
178 }
179
180 /*
181  * Set the access or default ACL of an inode.
182  *
183  * inode->i_mutex: down unless called from ext4_new_inode
184  */
185 static int
186 ext4_set_acl(handle_t *handle, struct inode *inode, int type,
187              struct posix_acl *acl)
188 {
189         int name_index;
190         void *value = NULL;
191         size_t size = 0;
192         int error;
193
194         if (S_ISLNK(inode->i_mode))
195                 return -EOPNOTSUPP;
196
197         switch (type) {
198         case ACL_TYPE_ACCESS:
199                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
200                 if (acl) {
201                         mode_t mode = inode->i_mode;
202                         error = posix_acl_equiv_mode(acl, &mode);
203                         if (error < 0)
204                                 return error;
205                         else {
206                                 inode->i_mode = mode;
207                                 inode->i_ctime = ext4_current_time(inode);
208                                 ext4_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 = EXT4_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 = ext4_acl_to_disk(acl, &size);
226                 if (IS_ERR(value))
227                         return (int)PTR_ERR(value);
228         }
229
230         error = ext4_xattr_set_handle(handle, inode, name_index, "",
231                                       value, size, 0);
232
233         kfree(value);
234         if (!error)
235                 set_cached_acl(inode, type, acl);
236
237         return error;
238 }
239
240 int
241 ext4_check_acl(struct inode *inode, int mask)
242 {
243         struct posix_acl *acl;
244
245         acl = ext4_get_acl(inode, ACL_TYPE_ACCESS);
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 /*
258  * Initialize the ACLs of a new inode. Called from ext4_new_inode.
259  *
260  * dir->i_mutex: down
261  * inode->i_mutex: up (access to inode is still exclusive)
262  */
263 int
264 ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
265 {
266         struct posix_acl *acl = NULL;
267         int error = 0;
268
269         if (!S_ISLNK(inode->i_mode)) {
270                 if (test_opt(dir->i_sb, POSIX_ACL)) {
271                         acl = ext4_get_acl(dir, ACL_TYPE_DEFAULT);
272                         if (IS_ERR(acl))
273                                 return PTR_ERR(acl);
274                 }
275                 if (!acl)
276                         inode->i_mode &= ~current_umask();
277         }
278         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
279                 struct posix_acl *clone;
280                 mode_t mode;
281
282                 if (S_ISDIR(inode->i_mode)) {
283                         error = ext4_set_acl(handle, inode,
284                                              ACL_TYPE_DEFAULT, acl);
285                         if (error)
286                                 goto cleanup;
287                 }
288                 clone = posix_acl_clone(acl, GFP_NOFS);
289                 error = -ENOMEM;
290                 if (!clone)
291                         goto cleanup;
292
293                 mode = inode->i_mode;
294                 error = posix_acl_create_masq(clone, &mode);
295                 if (error >= 0) {
296                         inode->i_mode = mode;
297                         if (error > 0) {
298                                 /* This is an extended ACL */
299                                 error = ext4_set_acl(handle, inode,
300                                                      ACL_TYPE_ACCESS, clone);
301                         }
302                 }
303                 posix_acl_release(clone);
304         }
305 cleanup:
306         posix_acl_release(acl);
307         return error;
308 }
309
310 /*
311  * Does chmod for an inode that may have an Access Control List. The
312  * inode->i_mode field must be updated to the desired value by the caller
313  * before calling this function.
314  * Returns 0 on success, or a negative error number.
315  *
316  * We change the ACL rather than storing some ACL entries in the file
317  * mode permission bits (which would be more efficient), because that
318  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
319  * for directories) are added. There are no more bits available in the
320  * file mode.
321  *
322  * inode->i_mutex: down
323  */
324 int
325 ext4_acl_chmod(struct inode *inode)
326 {
327         struct posix_acl *acl;
328         handle_t *handle;
329         int retries = 0;
330         int error;
331
332
333         if (S_ISLNK(inode->i_mode))
334                 return -EOPNOTSUPP;
335         if (!test_opt(inode->i_sb, POSIX_ACL))
336                 return 0;
337         acl = ext4_get_acl(inode, ACL_TYPE_ACCESS);
338         if (IS_ERR(acl) || !acl)
339                 return PTR_ERR(acl);
340         error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
341         if (error)
342                 return error;
343 retry:
344         handle = ext4_journal_start(inode,
345                         EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
346         if (IS_ERR(handle)) {
347                 error = PTR_ERR(handle);
348                 ext4_std_error(inode->i_sb, error);
349                 goto out;
350         }
351         error = ext4_set_acl(handle, inode, ACL_TYPE_ACCESS, acl);
352         ext4_journal_stop(handle);
353         if (error == -ENOSPC &&
354             ext4_should_retry_alloc(inode->i_sb, &retries))
355                 goto retry;
356 out:
357         posix_acl_release(acl);
358         return error;
359 }
360
361 /*
362  * Extended attribute handlers
363  */
364 static size_t
365 ext4_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_len,
366                            const char *name, size_t name_len, int type)
367 {
368         const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
369
370         if (!test_opt(dentry->d_sb, POSIX_ACL))
371                 return 0;
372         if (list && size <= list_len)
373                 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
374         return size;
375 }
376
377 static size_t
378 ext4_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_len,
379                             const char *name, size_t name_len, int type)
380 {
381         const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
382
383         if (!test_opt(dentry->d_sb, POSIX_ACL))
384                 return 0;
385         if (list && size <= list_len)
386                 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
387         return size;
388 }
389
390 static int
391 ext4_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer,
392                    size_t size, int type)
393 {
394         struct posix_acl *acl;
395         int error;
396
397         if (strcmp(name, "") != 0)
398                 return -EINVAL;
399         if (!test_opt(dentry->d_sb, POSIX_ACL))
400                 return -EOPNOTSUPP;
401
402         acl = ext4_get_acl(dentry->d_inode, type);
403         if (IS_ERR(acl))
404                 return PTR_ERR(acl);
405         if (acl == NULL)
406                 return -ENODATA;
407         error = posix_acl_to_xattr(acl, buffer, size);
408         posix_acl_release(acl);
409
410         return error;
411 }
412
413 static int
414 ext4_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
415                    size_t size, int flags, int type)
416 {
417         struct inode *inode = dentry->d_inode;
418         handle_t *handle;
419         struct posix_acl *acl;
420         int error, retries = 0;
421
422         if (strcmp(name, "") != 0)
423                 return -EINVAL;
424         if (!test_opt(inode->i_sb, POSIX_ACL))
425                 return -EOPNOTSUPP;
426         if (!inode_owner_or_capable(inode))
427                 return -EPERM;
428
429         if (value) {
430                 acl = posix_acl_from_xattr(value, size);
431                 if (IS_ERR(acl))
432                         return PTR_ERR(acl);
433                 else if (acl) {
434                         error = posix_acl_valid(acl);
435                         if (error)
436                                 goto release_and_out;
437                 }
438         } else
439                 acl = NULL;
440
441 retry:
442         handle = ext4_journal_start(inode, EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
443         if (IS_ERR(handle))
444                 return PTR_ERR(handle);
445         error = ext4_set_acl(handle, inode, type, acl);
446         ext4_journal_stop(handle);
447         if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
448                 goto retry;
449
450 release_and_out:
451         posix_acl_release(acl);
452         return error;
453 }
454
455 const struct xattr_handler ext4_xattr_acl_access_handler = {
456         .prefix = POSIX_ACL_XATTR_ACCESS,
457         .flags  = ACL_TYPE_ACCESS,
458         .list   = ext4_xattr_list_acl_access,
459         .get    = ext4_xattr_get_acl,
460         .set    = ext4_xattr_set_acl,
461 };
462
463 const struct xattr_handler ext4_xattr_acl_default_handler = {
464         .prefix = POSIX_ACL_XATTR_DEFAULT,
465         .flags  = ACL_TYPE_DEFAULT,
466         .list   = ext4_xattr_list_acl_default,
467         .get    = ext4_xattr_get_acl,
468         .set    = ext4_xattr_set_acl,
469 };