userns: rename is_owner_or_cap to inode_owner_or_capable
[linux-3.10.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                                         inode->i_ctime = CURRENT_TIME_SEC;
209                                         ext3_mark_inode_dirty(handle, inode);
210                                         if (error == 0)
211                                                 acl = NULL;
212                                 }
213                         }
214                         break;
215
216                 case ACL_TYPE_DEFAULT:
217                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
218                         if (!S_ISDIR(inode->i_mode))
219                                 return acl ? -EACCES : 0;
220                         break;
221
222                 default:
223                         return -EINVAL;
224         }
225         if (acl) {
226                 value = ext3_acl_to_disk(acl, &size);
227                 if (IS_ERR(value))
228                         return (int)PTR_ERR(value);
229         }
230
231         error = ext3_xattr_set_handle(handle, inode, name_index, "",
232                                       value, size, 0);
233
234         kfree(value);
235
236         if (!error)
237                 set_cached_acl(inode, type, acl);
238
239         return error;
240 }
241
242 int
243 ext3_check_acl(struct inode *inode, int mask, unsigned int flags)
244 {
245         struct posix_acl *acl;
246
247         if (flags & IPERM_FLAG_RCU) {
248                 if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
249                         return -ECHILD;
250                 return -EAGAIN;
251         }
252
253         acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
254         if (IS_ERR(acl))
255                 return PTR_ERR(acl);
256         if (acl) {
257                 int error = posix_acl_permission(inode, acl, mask);
258                 posix_acl_release(acl);
259                 return error;
260         }
261
262         return -EAGAIN;
263 }
264
265 /*
266  * Initialize the ACLs of a new inode. Called from ext3_new_inode.
267  *
268  * dir->i_mutex: down
269  * inode->i_mutex: up (access to inode is still exclusive)
270  */
271 int
272 ext3_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
273 {
274         struct posix_acl *acl = NULL;
275         int error = 0;
276
277         if (!S_ISLNK(inode->i_mode)) {
278                 if (test_opt(dir->i_sb, POSIX_ACL)) {
279                         acl = ext3_get_acl(dir, ACL_TYPE_DEFAULT);
280                         if (IS_ERR(acl))
281                                 return PTR_ERR(acl);
282                 }
283                 if (!acl)
284                         inode->i_mode &= ~current_umask();
285         }
286         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
287                 struct posix_acl *clone;
288                 mode_t mode;
289
290                 if (S_ISDIR(inode->i_mode)) {
291                         error = ext3_set_acl(handle, inode,
292                                              ACL_TYPE_DEFAULT, acl);
293                         if (error)
294                                 goto cleanup;
295                 }
296                 clone = posix_acl_clone(acl, GFP_NOFS);
297                 error = -ENOMEM;
298                 if (!clone)
299                         goto cleanup;
300
301                 mode = inode->i_mode;
302                 error = posix_acl_create_masq(clone, &mode);
303                 if (error >= 0) {
304                         inode->i_mode = mode;
305                         if (error > 0) {
306                                 /* This is an extended ACL */
307                                 error = ext3_set_acl(handle, inode,
308                                                      ACL_TYPE_ACCESS, clone);
309                         }
310                 }
311                 posix_acl_release(clone);
312         }
313 cleanup:
314         posix_acl_release(acl);
315         return error;
316 }
317
318 /*
319  * Does chmod for an inode that may have an Access Control List. The
320  * inode->i_mode field must be updated to the desired value by the caller
321  * before calling this function.
322  * Returns 0 on success, or a negative error number.
323  *
324  * We change the ACL rather than storing some ACL entries in the file
325  * mode permission bits (which would be more efficient), because that
326  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
327  * for directories) are added. There are no more bits available in the
328  * file mode.
329  *
330  * inode->i_mutex: down
331  */
332 int
333 ext3_acl_chmod(struct inode *inode)
334 {
335         struct posix_acl *acl, *clone;
336         int error;
337
338         if (S_ISLNK(inode->i_mode))
339                 return -EOPNOTSUPP;
340         if (!test_opt(inode->i_sb, POSIX_ACL))
341                 return 0;
342         acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
343         if (IS_ERR(acl) || !acl)
344                 return PTR_ERR(acl);
345         clone = posix_acl_clone(acl, GFP_KERNEL);
346         posix_acl_release(acl);
347         if (!clone)
348                 return -ENOMEM;
349         error = posix_acl_chmod_masq(clone, inode->i_mode);
350         if (!error) {
351                 handle_t *handle;
352                 int retries = 0;
353
354         retry:
355                 handle = ext3_journal_start(inode,
356                                 EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
357                 if (IS_ERR(handle)) {
358                         error = PTR_ERR(handle);
359                         ext3_std_error(inode->i_sb, error);
360                         goto out;
361                 }
362                 error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, clone);
363                 ext3_journal_stop(handle);
364                 if (error == -ENOSPC &&
365                     ext3_should_retry_alloc(inode->i_sb, &retries))
366                         goto retry;
367         }
368 out:
369         posix_acl_release(clone);
370         return error;
371 }
372
373 /*
374  * Extended attribute handlers
375  */
376 static size_t
377 ext3_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_len,
378                            const char *name, size_t name_len, int type)
379 {
380         const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
381
382         if (!test_opt(dentry->d_sb, POSIX_ACL))
383                 return 0;
384         if (list && size <= list_len)
385                 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
386         return size;
387 }
388
389 static size_t
390 ext3_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_len,
391                             const char *name, size_t name_len, int type)
392 {
393         const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
394
395         if (!test_opt(dentry->d_sb, POSIX_ACL))
396                 return 0;
397         if (list && size <= list_len)
398                 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
399         return size;
400 }
401
402 static int
403 ext3_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer,
404                    size_t size, int type)
405 {
406         struct posix_acl *acl;
407         int error;
408
409         if (strcmp(name, "") != 0)
410                 return -EINVAL;
411         if (!test_opt(dentry->d_sb, POSIX_ACL))
412                 return -EOPNOTSUPP;
413
414         acl = ext3_get_acl(dentry->d_inode, type);
415         if (IS_ERR(acl))
416                 return PTR_ERR(acl);
417         if (acl == NULL)
418                 return -ENODATA;
419         error = posix_acl_to_xattr(acl, buffer, size);
420         posix_acl_release(acl);
421
422         return error;
423 }
424
425 static int
426 ext3_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
427                    size_t size, int flags, int type)
428 {
429         struct inode *inode = dentry->d_inode;
430         handle_t *handle;
431         struct posix_acl *acl;
432         int error, retries = 0;
433
434         if (strcmp(name, "") != 0)
435                 return -EINVAL;
436         if (!test_opt(inode->i_sb, POSIX_ACL))
437                 return -EOPNOTSUPP;
438         if (!inode_owner_or_capable(inode))
439                 return -EPERM;
440
441         if (value) {
442                 acl = posix_acl_from_xattr(value, size);
443                 if (IS_ERR(acl))
444                         return PTR_ERR(acl);
445                 else if (acl) {
446                         error = posix_acl_valid(acl);
447                         if (error)
448                                 goto release_and_out;
449                 }
450         } else
451                 acl = NULL;
452
453 retry:
454         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
455         if (IS_ERR(handle))
456                 return PTR_ERR(handle);
457         error = ext3_set_acl(handle, inode, type, acl);
458         ext3_journal_stop(handle);
459         if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
460                 goto retry;
461
462 release_and_out:
463         posix_acl_release(acl);
464         return error;
465 }
466
467 const struct xattr_handler ext3_xattr_acl_access_handler = {
468         .prefix = POSIX_ACL_XATTR_ACCESS,
469         .flags  = ACL_TYPE_ACCESS,
470         .list   = ext3_xattr_list_acl_access,
471         .get    = ext3_xattr_get_acl,
472         .set    = ext3_xattr_set_acl,
473 };
474
475 const struct xattr_handler ext3_xattr_acl_default_handler = {
476         .prefix = POSIX_ACL_XATTR_DEFAULT,
477         .flags  = ACL_TYPE_DEFAULT,
478         .list   = ext3_xattr_list_acl_default,
479         .get    = ext3_xattr_get_acl,
480         .set    = ext3_xattr_set_acl,
481 };