[PATCH] aio: kiocb locking to serialise retry and cancel
[linux-2.6] / fs / ext2 / acl.c
1 /*
2  * linux/fs/ext2/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/fs.h>
11 #include "ext2.h"
12 #include "xattr.h"
13 #include "acl.h"
14
15 /*
16  * Convert from filesystem to in-memory representation.
17  */
18 static struct posix_acl *
19 ext2_acl_from_disk(const void *value, size_t size)
20 {
21         const char *end = (char *)value + size;
22         int n, count;
23         struct posix_acl *acl;
24
25         if (!value)
26                 return NULL;
27         if (size < sizeof(ext2_acl_header))
28                  return ERR_PTR(-EINVAL);
29         if (((ext2_acl_header *)value)->a_version !=
30             cpu_to_le32(EXT2_ACL_VERSION))
31                 return ERR_PTR(-EINVAL);
32         value = (char *)value + sizeof(ext2_acl_header);
33         count = ext2_acl_count(size);
34         if (count < 0)
35                 return ERR_PTR(-EINVAL);
36         if (count == 0)
37                 return NULL;
38         acl = posix_acl_alloc(count, GFP_KERNEL);
39         if (!acl)
40                 return ERR_PTR(-ENOMEM);
41         for (n=0; n < count; n++) {
42                 ext2_acl_entry *entry =
43                         (ext2_acl_entry *)value;
44                 if ((char *)value + sizeof(ext2_acl_entry_short) > end)
45                         goto fail;
46                 acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
47                 acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
48                 switch(acl->a_entries[n].e_tag) {
49                         case ACL_USER_OBJ:
50                         case ACL_GROUP_OBJ:
51                         case ACL_MASK:
52                         case ACL_OTHER:
53                                 value = (char *)value +
54                                         sizeof(ext2_acl_entry_short);
55                                 acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
56                                 break;
57
58                         case ACL_USER:
59                         case ACL_GROUP:
60                                 value = (char *)value + sizeof(ext2_acl_entry);
61                                 if ((char *)value > end)
62                                         goto fail;
63                                 acl->a_entries[n].e_id =
64                                         le32_to_cpu(entry->e_id);
65                                 break;
66
67                         default:
68                                 goto fail;
69                 }
70         }
71         if (value != end)
72                 goto fail;
73         return acl;
74
75 fail:
76         posix_acl_release(acl);
77         return ERR_PTR(-EINVAL);
78 }
79
80 /*
81  * Convert from in-memory to filesystem representation.
82  */
83 static void *
84 ext2_acl_to_disk(const struct posix_acl *acl, size_t *size)
85 {
86         ext2_acl_header *ext_acl;
87         char *e;
88         size_t n;
89
90         *size = ext2_acl_size(acl->a_count);
91         ext_acl = (ext2_acl_header *)kmalloc(sizeof(ext2_acl_header) +
92                 acl->a_count * sizeof(ext2_acl_entry), GFP_KERNEL);
93         if (!ext_acl)
94                 return ERR_PTR(-ENOMEM);
95         ext_acl->a_version = cpu_to_le32(EXT2_ACL_VERSION);
96         e = (char *)ext_acl + sizeof(ext2_acl_header);
97         for (n=0; n < acl->a_count; n++) {
98                 ext2_acl_entry *entry = (ext2_acl_entry *)e;
99                 entry->e_tag  = cpu_to_le16(acl->a_entries[n].e_tag);
100                 entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
101                 switch(acl->a_entries[n].e_tag) {
102                         case ACL_USER:
103                         case ACL_GROUP:
104                                 entry->e_id =
105                                         cpu_to_le32(acl->a_entries[n].e_id);
106                                 e += sizeof(ext2_acl_entry);
107                                 break;
108
109                         case ACL_USER_OBJ:
110                         case ACL_GROUP_OBJ:
111                         case ACL_MASK:
112                         case ACL_OTHER:
113                                 e += sizeof(ext2_acl_entry_short);
114                                 break;
115
116                         default:
117                                 goto fail;
118                 }
119         }
120         return (char *)ext_acl;
121
122 fail:
123         kfree(ext_acl);
124         return ERR_PTR(-EINVAL);
125 }
126
127 static inline struct posix_acl *
128 ext2_iget_acl(struct inode *inode, struct posix_acl **i_acl)
129 {
130         struct posix_acl *acl = EXT2_ACL_NOT_CACHED;
131
132         spin_lock(&inode->i_lock);
133         if (*i_acl != EXT2_ACL_NOT_CACHED)
134                 acl = posix_acl_dup(*i_acl);
135         spin_unlock(&inode->i_lock);
136
137         return acl;
138 }
139
140 static inline void
141 ext2_iset_acl(struct inode *inode, struct posix_acl **i_acl,
142                    struct posix_acl *acl)
143 {
144         spin_lock(&inode->i_lock);
145         if (*i_acl != EXT2_ACL_NOT_CACHED)
146                 posix_acl_release(*i_acl);
147         *i_acl = posix_acl_dup(acl);
148         spin_unlock(&inode->i_lock);
149 }
150
151 /*
152  * inode->i_sem: don't care
153  */
154 static struct posix_acl *
155 ext2_get_acl(struct inode *inode, int type)
156 {
157         struct ext2_inode_info *ei = EXT2_I(inode);
158         int name_index;
159         char *value = NULL;
160         struct posix_acl *acl;
161         int retval;
162
163         if (!test_opt(inode->i_sb, POSIX_ACL))
164                 return NULL;
165
166         switch(type) {
167                 case ACL_TYPE_ACCESS:
168                         acl = ext2_iget_acl(inode, &ei->i_acl);
169                         if (acl != EXT2_ACL_NOT_CACHED)
170                                 return acl;
171                         name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
172                         break;
173
174                 case ACL_TYPE_DEFAULT:
175                         acl = ext2_iget_acl(inode, &ei->i_default_acl);
176                         if (acl != EXT2_ACL_NOT_CACHED)
177                                 return acl;
178                         name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
179                         break;
180
181                 default:
182                         return ERR_PTR(-EINVAL);
183         }
184         retval = ext2_xattr_get(inode, name_index, "", NULL, 0);
185         if (retval > 0) {
186                 value = kmalloc(retval, GFP_KERNEL);
187                 if (!value)
188                         return ERR_PTR(-ENOMEM);
189                 retval = ext2_xattr_get(inode, name_index, "", value, retval);
190         }
191         if (retval > 0)
192                 acl = ext2_acl_from_disk(value, retval);
193         else if (retval == -ENODATA || retval == -ENOSYS)
194                 acl = NULL;
195         else
196                 acl = ERR_PTR(retval);
197         if (value)
198                 kfree(value);
199
200         if (!IS_ERR(acl)) {
201                 switch(type) {
202                         case ACL_TYPE_ACCESS:
203                                 ext2_iset_acl(inode, &ei->i_acl, acl);
204                                 break;
205
206                         case ACL_TYPE_DEFAULT:
207                                 ext2_iset_acl(inode, &ei->i_default_acl, acl);
208                                 break;
209                 }
210         }
211         return acl;
212 }
213
214 /*
215  * inode->i_sem: down
216  */
217 static int
218 ext2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
219 {
220         struct ext2_inode_info *ei = EXT2_I(inode);
221         int name_index;
222         void *value = NULL;
223         size_t size;
224         int error;
225
226         if (S_ISLNK(inode->i_mode))
227                 return -EOPNOTSUPP;
228         if (!test_opt(inode->i_sb, POSIX_ACL))
229                 return 0;
230
231         switch(type) {
232                 case ACL_TYPE_ACCESS:
233                         name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
234                         if (acl) {
235                                 mode_t mode = inode->i_mode;
236                                 error = posix_acl_equiv_mode(acl, &mode);
237                                 if (error < 0)
238                                         return error;
239                                 else {
240                                         inode->i_mode = mode;
241                                         mark_inode_dirty(inode);
242                                         if (error == 0)
243                                                 acl = NULL;
244                                 }
245                         }
246                         break;
247
248                 case ACL_TYPE_DEFAULT:
249                         name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
250                         if (!S_ISDIR(inode->i_mode))
251                                 return acl ? -EACCES : 0;
252                         break;
253
254                 default:
255                         return -EINVAL;
256         }
257         if (acl) {
258                 value = ext2_acl_to_disk(acl, &size);
259                 if (IS_ERR(value))
260                         return (int)PTR_ERR(value);
261         }
262
263         error = ext2_xattr_set(inode, name_index, "", value, size, 0);
264
265         if (value)
266                 kfree(value);
267         if (!error) {
268                 switch(type) {
269                         case ACL_TYPE_ACCESS:
270                                 ext2_iset_acl(inode, &ei->i_acl, acl);
271                                 break;
272
273                         case ACL_TYPE_DEFAULT:
274                                 ext2_iset_acl(inode, &ei->i_default_acl, acl);
275                                 break;
276                 }
277         }
278         return error;
279 }
280
281 static int
282 ext2_check_acl(struct inode *inode, int mask)
283 {
284         struct posix_acl *acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
285
286         if (IS_ERR(acl))
287                 return PTR_ERR(acl);
288         if (acl) {
289                 int error = posix_acl_permission(inode, acl, mask);
290                 posix_acl_release(acl);
291                 return error;
292         }
293
294         return -EAGAIN;
295 }
296
297 int
298 ext2_permission(struct inode *inode, int mask, struct nameidata *nd)
299 {
300         return generic_permission(inode, mask, ext2_check_acl);
301 }
302
303 /*
304  * Initialize the ACLs of a new inode. Called from ext2_new_inode.
305  *
306  * dir->i_sem: down
307  * inode->i_sem: up (access to inode is still exclusive)
308  */
309 int
310 ext2_init_acl(struct inode *inode, struct inode *dir)
311 {
312         struct posix_acl *acl = NULL;
313         int error = 0;
314
315         if (!S_ISLNK(inode->i_mode)) {
316                 if (test_opt(dir->i_sb, POSIX_ACL)) {
317                         acl = ext2_get_acl(dir, ACL_TYPE_DEFAULT);
318                         if (IS_ERR(acl))
319                                 return PTR_ERR(acl);
320                 }
321                 if (!acl)
322                         inode->i_mode &= ~current->fs->umask;
323         }
324         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
325                struct posix_acl *clone;
326                mode_t mode;
327
328                 if (S_ISDIR(inode->i_mode)) {
329                         error = ext2_set_acl(inode, ACL_TYPE_DEFAULT, acl);
330                         if (error)
331                                 goto cleanup;
332                 }
333                 clone = posix_acl_clone(acl, GFP_KERNEL);
334                 error = -ENOMEM;
335                 if (!clone)
336                         goto cleanup;
337                 mode = inode->i_mode;
338                 error = posix_acl_create_masq(clone, &mode);
339                 if (error >= 0) {
340                         inode->i_mode = mode;
341                         if (error > 0) {
342                                 /* This is an extended ACL */
343                                 error = ext2_set_acl(inode,
344                                                      ACL_TYPE_ACCESS, clone);
345                         }
346                 }
347                 posix_acl_release(clone);
348         }
349 cleanup:
350        posix_acl_release(acl);
351        return error;
352 }
353
354 /*
355  * Does chmod for an inode that may have an Access Control List. The
356  * inode->i_mode field must be updated to the desired value by the caller
357  * before calling this function.
358  * Returns 0 on success, or a negative error number.
359  *
360  * We change the ACL rather than storing some ACL entries in the file
361  * mode permission bits (which would be more efficient), because that
362  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
363  * for directories) are added. There are no more bits available in the
364  * file mode.
365  *
366  * inode->i_sem: down
367  */
368 int
369 ext2_acl_chmod(struct inode *inode)
370 {
371         struct posix_acl *acl, *clone;
372         int error;
373
374         if (!test_opt(inode->i_sb, POSIX_ACL))
375                 return 0;
376         if (S_ISLNK(inode->i_mode))
377                 return -EOPNOTSUPP;
378         acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
379         if (IS_ERR(acl) || !acl)
380                 return PTR_ERR(acl);
381         clone = posix_acl_clone(acl, GFP_KERNEL);
382         posix_acl_release(acl);
383         if (!clone)
384                 return -ENOMEM;
385         error = posix_acl_chmod_masq(clone, inode->i_mode);
386         if (!error)
387                 error = ext2_set_acl(inode, ACL_TYPE_ACCESS, clone);
388         posix_acl_release(clone);
389         return error;
390 }
391
392 /*
393  * Extended attribut handlers
394  */
395 static size_t
396 ext2_xattr_list_acl_access(struct inode *inode, char *list, size_t list_size,
397                            const char *name, size_t name_len)
398 {
399         const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
400
401         if (!test_opt(inode->i_sb, POSIX_ACL))
402                 return 0;
403         if (list && size <= list_size)
404                 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
405         return size;
406 }
407
408 static size_t
409 ext2_xattr_list_acl_default(struct inode *inode, char *list, size_t list_size,
410                             const char *name, size_t name_len)
411 {
412         const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
413
414         if (!test_opt(inode->i_sb, POSIX_ACL))
415                 return 0;
416         if (list && size <= list_size)
417                 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
418         return size;
419 }
420
421 static int
422 ext2_xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size)
423 {
424         struct posix_acl *acl;
425         int error;
426
427         if (!test_opt(inode->i_sb, POSIX_ACL))
428                 return -EOPNOTSUPP;
429
430         acl = ext2_get_acl(inode, type);
431         if (IS_ERR(acl))
432                 return PTR_ERR(acl);
433         if (acl == NULL)
434                 return -ENODATA;
435         error = posix_acl_to_xattr(acl, buffer, size);
436         posix_acl_release(acl);
437
438         return error;
439 }
440
441 static int
442 ext2_xattr_get_acl_access(struct inode *inode, const char *name,
443                           void *buffer, size_t size)
444 {
445         if (strcmp(name, "") != 0)
446                 return -EINVAL;
447         return ext2_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
448 }
449
450 static int
451 ext2_xattr_get_acl_default(struct inode *inode, const char *name,
452                            void *buffer, size_t size)
453 {
454         if (strcmp(name, "") != 0)
455                 return -EINVAL;
456         return ext2_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
457 }
458
459 static int
460 ext2_xattr_set_acl(struct inode *inode, int type, const void *value,
461                    size_t size)
462 {
463         struct posix_acl *acl;
464         int error;
465
466         if (!test_opt(inode->i_sb, POSIX_ACL))
467                 return -EOPNOTSUPP;
468         if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
469                 return -EPERM;
470
471         if (value) {
472                 acl = posix_acl_from_xattr(value, size);
473                 if (IS_ERR(acl))
474                         return PTR_ERR(acl);
475                 else if (acl) {
476                         error = posix_acl_valid(acl);
477                         if (error)
478                                 goto release_and_out;
479                 }
480         } else
481                 acl = NULL;
482
483         error = ext2_set_acl(inode, type, acl);
484
485 release_and_out:
486         posix_acl_release(acl);
487         return error;
488 }
489
490 static int
491 ext2_xattr_set_acl_access(struct inode *inode, const char *name,
492                           const void *value, size_t size, int flags)
493 {
494         if (strcmp(name, "") != 0)
495                 return -EINVAL;
496         return ext2_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
497 }
498
499 static int
500 ext2_xattr_set_acl_default(struct inode *inode, const char *name,
501                            const void *value, size_t size, int flags)
502 {
503         if (strcmp(name, "") != 0)
504                 return -EINVAL;
505         return ext2_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
506 }
507
508 struct xattr_handler ext2_xattr_acl_access_handler = {
509         .prefix = POSIX_ACL_XATTR_ACCESS,
510         .list   = ext2_xattr_list_acl_access,
511         .get    = ext2_xattr_get_acl_access,
512         .set    = ext2_xattr_set_acl_access,
513 };
514
515 struct xattr_handler ext2_xattr_acl_default_handler = {
516         .prefix = POSIX_ACL_XATTR_DEFAULT,
517         .list   = ext2_xattr_list_acl_default,
518         .get    = ext2_xattr_get_acl_default,
519         .set    = ext2_xattr_set_acl_default,
520 };