ced1c478ebdb4873afe1175005288055c00840e1
[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                                         inode->i_ctime = CURRENT_TIME_SEC;
204                                         mark_inode_dirty(inode);
205                                         if (error == 0)
206                                                 acl = NULL;
207                                 }
208                         }
209                         break;
210
211                 case ACL_TYPE_DEFAULT:
212                         name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
213                         if (!S_ISDIR(inode->i_mode))
214                                 return acl ? -EACCES : 0;
215                         break;
216
217                 default:
218                         return -EINVAL;
219         }
220         if (acl) {
221                 value = ext2_acl_to_disk(acl, &size);
222                 if (IS_ERR(value))
223                         return (int)PTR_ERR(value);
224         }
225
226         error = ext2_xattr_set(inode, name_index, "", value, size, 0);
227
228         kfree(value);
229         if (!error)
230                 set_cached_acl(inode, type, acl);
231         return error;
232 }
233
234 int
235 ext2_check_acl(struct inode *inode, int mask)
236 {
237         struct posix_acl *acl;
238
239         acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
240         if (IS_ERR(acl))
241                 return PTR_ERR(acl);
242         if (acl) {
243                 int error = posix_acl_permission(inode, acl, mask);
244                 posix_acl_release(acl);
245                 return error;
246         }
247
248         return -EAGAIN;
249 }
250
251 /*
252  * Initialize the ACLs of a new inode. Called from ext2_new_inode.
253  *
254  * dir->i_mutex: down
255  * inode->i_mutex: up (access to inode is still exclusive)
256  */
257 int
258 ext2_init_acl(struct inode *inode, struct inode *dir)
259 {
260         struct posix_acl *acl = NULL;
261         int error = 0;
262
263         if (!S_ISLNK(inode->i_mode)) {
264                 if (test_opt(dir->i_sb, POSIX_ACL)) {
265                         acl = ext2_get_acl(dir, ACL_TYPE_DEFAULT);
266                         if (IS_ERR(acl))
267                                 return PTR_ERR(acl);
268                 }
269                 if (!acl)
270                         inode->i_mode &= ~current_umask();
271         }
272         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
273                struct posix_acl *clone;
274                mode_t mode;
275
276                 if (S_ISDIR(inode->i_mode)) {
277                         error = ext2_set_acl(inode, ACL_TYPE_DEFAULT, acl);
278                         if (error)
279                                 goto cleanup;
280                 }
281                 clone = posix_acl_clone(acl, GFP_KERNEL);
282                 error = -ENOMEM;
283                 if (!clone)
284                         goto cleanup;
285                 mode = inode->i_mode;
286                 error = posix_acl_create_masq(clone, &mode);
287                 if (error >= 0) {
288                         inode->i_mode = mode;
289                         if (error > 0) {
290                                 /* This is an extended ACL */
291                                 error = ext2_set_acl(inode,
292                                                      ACL_TYPE_ACCESS, clone);
293                         }
294                 }
295                 posix_acl_release(clone);
296         }
297 cleanup:
298        posix_acl_release(acl);
299        return error;
300 }
301
302 /*
303  * Does chmod for an inode that may have an Access Control List. The
304  * inode->i_mode field must be updated to the desired value by the caller
305  * before calling this function.
306  * Returns 0 on success, or a negative error number.
307  *
308  * We change the ACL rather than storing some ACL entries in the file
309  * mode permission bits (which would be more efficient), because that
310  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
311  * for directories) are added. There are no more bits available in the
312  * file mode.
313  *
314  * inode->i_mutex: down
315  */
316 int
317 ext2_acl_chmod(struct inode *inode)
318 {
319         struct posix_acl *acl, *clone;
320         int error;
321
322         if (!test_opt(inode->i_sb, POSIX_ACL))
323                 return 0;
324         if (S_ISLNK(inode->i_mode))
325                 return -EOPNOTSUPP;
326         acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
327         if (IS_ERR(acl) || !acl)
328                 return PTR_ERR(acl);
329         clone = posix_acl_clone(acl, GFP_KERNEL);
330         posix_acl_release(acl);
331         if (!clone)
332                 return -ENOMEM;
333         error = posix_acl_chmod_masq(clone, inode->i_mode);
334         if (!error)
335                 error = ext2_set_acl(inode, ACL_TYPE_ACCESS, clone);
336         posix_acl_release(clone);
337         return error;
338 }
339
340 /*
341  * Extended attribut handlers
342  */
343 static size_t
344 ext2_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_size,
345                            const char *name, size_t name_len, int type)
346 {
347         const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
348
349         if (!test_opt(dentry->d_sb, POSIX_ACL))
350                 return 0;
351         if (list && size <= list_size)
352                 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
353         return size;
354 }
355
356 static size_t
357 ext2_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_size,
358                             const char *name, size_t name_len, int type)
359 {
360         const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
361
362         if (!test_opt(dentry->d_sb, POSIX_ACL))
363                 return 0;
364         if (list && size <= list_size)
365                 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
366         return size;
367 }
368
369 static int
370 ext2_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer,
371                    size_t size, int type)
372 {
373         struct posix_acl *acl;
374         int error;
375
376         if (strcmp(name, "") != 0)
377                 return -EINVAL;
378         if (!test_opt(dentry->d_sb, POSIX_ACL))
379                 return -EOPNOTSUPP;
380
381         acl = ext2_get_acl(dentry->d_inode, type);
382         if (IS_ERR(acl))
383                 return PTR_ERR(acl);
384         if (acl == NULL)
385                 return -ENODATA;
386         error = posix_acl_to_xattr(acl, buffer, size);
387         posix_acl_release(acl);
388
389         return error;
390 }
391
392 static int
393 ext2_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
394                    size_t size, int flags, int type)
395 {
396         struct posix_acl *acl;
397         int error;
398
399         if (strcmp(name, "") != 0)
400                 return -EINVAL;
401         if (!test_opt(dentry->d_sb, POSIX_ACL))
402                 return -EOPNOTSUPP;
403         if (!inode_owner_or_capable(dentry->d_inode))
404                 return -EPERM;
405
406         if (value) {
407                 acl = posix_acl_from_xattr(value, size);
408                 if (IS_ERR(acl))
409                         return PTR_ERR(acl);
410                 else if (acl) {
411                         error = posix_acl_valid(acl);
412                         if (error)
413                                 goto release_and_out;
414                 }
415         } else
416                 acl = NULL;
417
418         error = ext2_set_acl(dentry->d_inode, type, acl);
419
420 release_and_out:
421         posix_acl_release(acl);
422         return error;
423 }
424
425 const struct xattr_handler ext2_xattr_acl_access_handler = {
426         .prefix = POSIX_ACL_XATTR_ACCESS,
427         .flags  = ACL_TYPE_ACCESS,
428         .list   = ext2_xattr_list_acl_access,
429         .get    = ext2_xattr_get_acl,
430         .set    = ext2_xattr_set_acl,
431 };
432
433 const struct xattr_handler ext2_xattr_acl_default_handler = {
434         .prefix = POSIX_ACL_XATTR_DEFAULT,
435         .flags  = ACL_TYPE_DEFAULT,
436         .list   = ext2_xattr_list_acl_default,
437         .get    = ext2_xattr_get_acl,
438         .set    = ext2_xattr_set_acl,
439 };