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