switch posix_acl_create() to umode_t *
[linux-3.10.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 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 /*
241  * Initialize the ACLs of a new inode. Called from ext4_new_inode.
242  *
243  * dir->i_mutex: down
244  * inode->i_mutex: up (access to inode is still exclusive)
245  */
246 int
247 ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
248 {
249         struct posix_acl *acl = NULL;
250         int error = 0;
251
252         if (!S_ISLNK(inode->i_mode)) {
253                 if (test_opt(dir->i_sb, POSIX_ACL)) {
254                         acl = ext4_get_acl(dir, ACL_TYPE_DEFAULT);
255                         if (IS_ERR(acl))
256                                 return PTR_ERR(acl);
257                 }
258                 if (!acl)
259                         inode->i_mode &= ~current_umask();
260         }
261         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
262                 if (S_ISDIR(inode->i_mode)) {
263                         error = ext4_set_acl(handle, inode,
264                                              ACL_TYPE_DEFAULT, acl);
265                         if (error)
266                                 goto cleanup;
267                 }
268                 error = posix_acl_create(&acl, GFP_NOFS, &inode->i_mode);
269                 if (error < 0)
270                         return error;
271
272                 if (error > 0) {
273                         /* This is an extended ACL */
274                         error = ext4_set_acl(handle, inode, ACL_TYPE_ACCESS, acl);
275                 }
276         }
277 cleanup:
278         posix_acl_release(acl);
279         return error;
280 }
281
282 /*
283  * Does chmod for an inode that may have an Access Control List. The
284  * inode->i_mode field must be updated to the desired value by the caller
285  * before calling this function.
286  * Returns 0 on success, or a negative error number.
287  *
288  * We change the ACL rather than storing some ACL entries in the file
289  * mode permission bits (which would be more efficient), because that
290  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
291  * for directories) are added. There are no more bits available in the
292  * file mode.
293  *
294  * inode->i_mutex: down
295  */
296 int
297 ext4_acl_chmod(struct inode *inode)
298 {
299         struct posix_acl *acl;
300         handle_t *handle;
301         int retries = 0;
302         int error;
303
304
305         if (S_ISLNK(inode->i_mode))
306                 return -EOPNOTSUPP;
307         if (!test_opt(inode->i_sb, POSIX_ACL))
308                 return 0;
309         acl = ext4_get_acl(inode, ACL_TYPE_ACCESS);
310         if (IS_ERR(acl) || !acl)
311                 return PTR_ERR(acl);
312         error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
313         if (error)
314                 return error;
315 retry:
316         handle = ext4_journal_start(inode,
317                         EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
318         if (IS_ERR(handle)) {
319                 error = PTR_ERR(handle);
320                 ext4_std_error(inode->i_sb, error);
321                 goto out;
322         }
323         error = ext4_set_acl(handle, inode, ACL_TYPE_ACCESS, acl);
324         ext4_journal_stop(handle);
325         if (error == -ENOSPC &&
326             ext4_should_retry_alloc(inode->i_sb, &retries))
327                 goto retry;
328 out:
329         posix_acl_release(acl);
330         return error;
331 }
332
333 /*
334  * Extended attribute handlers
335  */
336 static size_t
337 ext4_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_len,
338                            const char *name, size_t name_len, int type)
339 {
340         const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
341
342         if (!test_opt(dentry->d_sb, POSIX_ACL))
343                 return 0;
344         if (list && size <= list_len)
345                 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
346         return size;
347 }
348
349 static size_t
350 ext4_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_len,
351                             const char *name, size_t name_len, int type)
352 {
353         const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
354
355         if (!test_opt(dentry->d_sb, POSIX_ACL))
356                 return 0;
357         if (list && size <= list_len)
358                 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
359         return size;
360 }
361
362 static int
363 ext4_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer,
364                    size_t size, int type)
365 {
366         struct posix_acl *acl;
367         int error;
368
369         if (strcmp(name, "") != 0)
370                 return -EINVAL;
371         if (!test_opt(dentry->d_sb, POSIX_ACL))
372                 return -EOPNOTSUPP;
373
374         acl = ext4_get_acl(dentry->d_inode, type);
375         if (IS_ERR(acl))
376                 return PTR_ERR(acl);
377         if (acl == NULL)
378                 return -ENODATA;
379         error = posix_acl_to_xattr(acl, buffer, size);
380         posix_acl_release(acl);
381
382         return error;
383 }
384
385 static int
386 ext4_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
387                    size_t size, int flags, int type)
388 {
389         struct inode *inode = dentry->d_inode;
390         handle_t *handle;
391         struct posix_acl *acl;
392         int error, retries = 0;
393
394         if (strcmp(name, "") != 0)
395                 return -EINVAL;
396         if (!test_opt(inode->i_sb, POSIX_ACL))
397                 return -EOPNOTSUPP;
398         if (!inode_owner_or_capable(inode))
399                 return -EPERM;
400
401         if (value) {
402                 acl = posix_acl_from_xattr(value, size);
403                 if (IS_ERR(acl))
404                         return PTR_ERR(acl);
405                 else if (acl) {
406                         error = posix_acl_valid(acl);
407                         if (error)
408                                 goto release_and_out;
409                 }
410         } else
411                 acl = NULL;
412
413 retry:
414         handle = ext4_journal_start(inode, EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
415         if (IS_ERR(handle))
416                 return PTR_ERR(handle);
417         error = ext4_set_acl(handle, inode, type, acl);
418         ext4_journal_stop(handle);
419         if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
420                 goto retry;
421
422 release_and_out:
423         posix_acl_release(acl);
424         return error;
425 }
426
427 const struct xattr_handler ext4_xattr_acl_access_handler = {
428         .prefix = POSIX_ACL_XATTR_ACCESS,
429         .flags  = ACL_TYPE_ACCESS,
430         .list   = ext4_xattr_list_acl_access,
431         .get    = ext4_xattr_get_acl,
432         .set    = ext4_xattr_set_acl,
433 };
434
435 const struct xattr_handler ext4_xattr_acl_default_handler = {
436         .prefix = POSIX_ACL_XATTR_DEFAULT,
437         .flags  = ACL_TYPE_DEFAULT,
438         .list   = ext4_xattr_list_acl_default,
439         .get    = ext4_xattr_get_acl,
440         .set    = ext4_xattr_set_acl,
441 };