5326038e8536a60563325eb0c90cf2cf06f6284d
[linux-2.6.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)
244 {
245         struct posix_acl *acl;
246
247         acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
248         if (IS_ERR(acl))
249                 return PTR_ERR(acl);
250         if (acl) {
251                 int error = posix_acl_permission(inode, acl, mask);
252                 posix_acl_release(acl);
253                 return error;
254         }
255
256         return -EAGAIN;
257 }
258
259 /*
260  * Initialize the ACLs of a new inode. Called from ext3_new_inode.
261  *
262  * dir->i_mutex: down
263  * inode->i_mutex: up (access to inode is still exclusive)
264  */
265 int
266 ext3_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
267 {
268         struct posix_acl *acl = NULL;
269         int error = 0;
270
271         if (!S_ISLNK(inode->i_mode)) {
272                 if (test_opt(dir->i_sb, POSIX_ACL)) {
273                         acl = ext3_get_acl(dir, ACL_TYPE_DEFAULT);
274                         if (IS_ERR(acl))
275                                 return PTR_ERR(acl);
276                 }
277                 if (!acl)
278                         inode->i_mode &= ~current_umask();
279         }
280         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
281                 struct posix_acl *clone;
282                 mode_t mode;
283
284                 if (S_ISDIR(inode->i_mode)) {
285                         error = ext3_set_acl(handle, inode,
286                                              ACL_TYPE_DEFAULT, acl);
287                         if (error)
288                                 goto cleanup;
289                 }
290                 clone = posix_acl_clone(acl, GFP_NOFS);
291                 error = -ENOMEM;
292                 if (!clone)
293                         goto cleanup;
294
295                 mode = inode->i_mode;
296                 error = posix_acl_create_masq(clone, &mode);
297                 if (error >= 0) {
298                         inode->i_mode = mode;
299                         if (error > 0) {
300                                 /* This is an extended ACL */
301                                 error = ext3_set_acl(handle, inode,
302                                                      ACL_TYPE_ACCESS, clone);
303                         }
304                 }
305                 posix_acl_release(clone);
306         }
307 cleanup:
308         posix_acl_release(acl);
309         return error;
310 }
311
312 /*
313  * Does chmod for an inode that may have an Access Control List. The
314  * inode->i_mode field must be updated to the desired value by the caller
315  * before calling this function.
316  * Returns 0 on success, or a negative error number.
317  *
318  * We change the ACL rather than storing some ACL entries in the file
319  * mode permission bits (which would be more efficient), because that
320  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
321  * for directories) are added. There are no more bits available in the
322  * file mode.
323  *
324  * inode->i_mutex: down
325  */
326 int
327 ext3_acl_chmod(struct inode *inode)
328 {
329         struct posix_acl *acl, *clone;
330         int error;
331
332         if (S_ISLNK(inode->i_mode))
333                 return -EOPNOTSUPP;
334         if (!test_opt(inode->i_sb, POSIX_ACL))
335                 return 0;
336         acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
337         if (IS_ERR(acl) || !acl)
338                 return PTR_ERR(acl);
339         clone = posix_acl_clone(acl, GFP_KERNEL);
340         posix_acl_release(acl);
341         if (!clone)
342                 return -ENOMEM;
343         error = posix_acl_chmod_masq(clone, inode->i_mode);
344         if (!error) {
345                 handle_t *handle;
346                 int retries = 0;
347
348         retry:
349                 handle = ext3_journal_start(inode,
350                                 EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
351                 if (IS_ERR(handle)) {
352                         error = PTR_ERR(handle);
353                         ext3_std_error(inode->i_sb, error);
354                         goto out;
355                 }
356                 error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, clone);
357                 ext3_journal_stop(handle);
358                 if (error == -ENOSPC &&
359                     ext3_should_retry_alloc(inode->i_sb, &retries))
360                         goto retry;
361         }
362 out:
363         posix_acl_release(clone);
364         return error;
365 }
366
367 /*
368  * Extended attribute handlers
369  */
370 static size_t
371 ext3_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_len,
372                            const char *name, size_t name_len, int type)
373 {
374         const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
375
376         if (!test_opt(dentry->d_sb, POSIX_ACL))
377                 return 0;
378         if (list && size <= list_len)
379                 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
380         return size;
381 }
382
383 static size_t
384 ext3_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_len,
385                             const char *name, size_t name_len, int type)
386 {
387         const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
388
389         if (!test_opt(dentry->d_sb, POSIX_ACL))
390                 return 0;
391         if (list && size <= list_len)
392                 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
393         return size;
394 }
395
396 static int
397 ext3_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer,
398                    size_t size, int type)
399 {
400         struct posix_acl *acl;
401         int error;
402
403         if (strcmp(name, "") != 0)
404                 return -EINVAL;
405         if (!test_opt(dentry->d_sb, POSIX_ACL))
406                 return -EOPNOTSUPP;
407
408         acl = ext3_get_acl(dentry->d_inode, type);
409         if (IS_ERR(acl))
410                 return PTR_ERR(acl);
411         if (acl == NULL)
412                 return -ENODATA;
413         error = posix_acl_to_xattr(acl, buffer, size);
414         posix_acl_release(acl);
415
416         return error;
417 }
418
419 static int
420 ext3_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
421                    size_t size, int flags, int type)
422 {
423         struct inode *inode = dentry->d_inode;
424         handle_t *handle;
425         struct posix_acl *acl;
426         int error, retries = 0;
427
428         if (strcmp(name, "") != 0)
429                 return -EINVAL;
430         if (!test_opt(inode->i_sb, POSIX_ACL))
431                 return -EOPNOTSUPP;
432         if (!inode_owner_or_capable(inode))
433                 return -EPERM;
434
435         if (value) {
436                 acl = posix_acl_from_xattr(value, size);
437                 if (IS_ERR(acl))
438                         return PTR_ERR(acl);
439                 else if (acl) {
440                         error = posix_acl_valid(acl);
441                         if (error)
442                                 goto release_and_out;
443                 }
444         } else
445                 acl = NULL;
446
447 retry:
448         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
449         if (IS_ERR(handle))
450                 return PTR_ERR(handle);
451         error = ext3_set_acl(handle, inode, type, acl);
452         ext3_journal_stop(handle);
453         if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
454                 goto retry;
455
456 release_and_out:
457         posix_acl_release(acl);
458         return error;
459 }
460
461 const struct xattr_handler ext3_xattr_acl_access_handler = {
462         .prefix = POSIX_ACL_XATTR_ACCESS,
463         .flags  = ACL_TYPE_ACCESS,
464         .list   = ext3_xattr_list_acl_access,
465         .get    = ext3_xattr_get_acl,
466         .set    = ext3_xattr_set_acl,
467 };
468
469 const struct xattr_handler ext3_xattr_acl_default_handler = {
470         .prefix = POSIX_ACL_XATTR_DEFAULT,
471         .flags  = ACL_TYPE_DEFAULT,
472         .list   = ext3_xattr_list_acl_default,
473         .get    = ext3_xattr_get_acl,
474         .set    = ext3_xattr_set_acl,
475 };