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ext2: constify xattr_handler
[net-next-2.6.git] / fs / ext2 / acl.c
CommitLineData
1da177e4
LT
1/*
2 * linux/fs/ext2/acl.c
3 *
4 * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
5 */
6
16f7e0fe 7#include <linux/capability.h>
1da177e4
LT
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 */
19static struct posix_acl *
20ext2_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
76fail:
77 posix_acl_release(acl);
78 return ERR_PTR(-EINVAL);
79}
80
81/*
82 * Convert from in-memory to filesystem representation.
83 */
84static void *
85ext2_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);
f52720ca
PI
92 ext_acl = kmalloc(sizeof(ext2_acl_header) + acl->a_count *
93 sizeof(ext2_acl_entry), GFP_KERNEL);
1da177e4
LT
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
123fail:
124 kfree(ext_acl);
125 return ERR_PTR(-EINVAL);
126}
127
1da177e4 128/*
1b1dcc1b 129 * inode->i_mutex: don't care
1da177e4
LT
130 */
131static struct posix_acl *
132ext2_get_acl(struct inode *inode, int type)
133{
1da177e4
LT
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
073aaa1b
AV
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();
1da177e4
LT
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);
f99d49ad 169 kfree(value);
1da177e4 170
073aaa1b
AV
171 if (!IS_ERR(acl))
172 set_cached_acl(inode, type, acl);
1da177e4 173
1da177e4
LT
174 return acl;
175}
176
177/*
1b1dcc1b 178 * inode->i_mutex: down
1da177e4
LT
179 */
180static int
181ext2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
182{
1da177e4
LT
183 int name_index;
184 void *value = NULL;
dfa08592 185 size_t size = 0;
1da177e4
LT
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
f99d49ad 227 kfree(value);
073aaa1b
AV
228 if (!error)
229 set_cached_acl(inode, type, acl);
1da177e4
LT
230 return error;
231}
232
1d5ccd1c 233int
1da177e4
LT
234ext2_check_acl(struct inode *inode, int mask)
235{
236 struct posix_acl *acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
237
e493073d
AM
238 if (IS_ERR(acl))
239 return PTR_ERR(acl);
1da177e4
LT
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
1da177e4
LT
249/*
250 * Initialize the ACLs of a new inode. Called from ext2_new_inode.
251 *
1b1dcc1b
JS
252 * dir->i_mutex: down
253 * inode->i_mutex: up (access to inode is still exclusive)
1da177e4
LT
254 */
255int
256ext2_init_acl(struct inode *inode, struct inode *dir)
257{
258 struct posix_acl *acl = NULL;
259 int error = 0;
260
261 if (!S_ISLNK(inode->i_mode)) {
262 if (test_opt(dir->i_sb, POSIX_ACL)) {
263 acl = ext2_get_acl(dir, ACL_TYPE_DEFAULT);
264 if (IS_ERR(acl))
265 return PTR_ERR(acl);
266 }
267 if (!acl)
ce3b0f8d 268 inode->i_mode &= ~current_umask();
1da177e4
LT
269 }
270 if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
271 struct posix_acl *clone;
272 mode_t mode;
273
274 if (S_ISDIR(inode->i_mode)) {
275 error = ext2_set_acl(inode, ACL_TYPE_DEFAULT, acl);
276 if (error)
277 goto cleanup;
278 }
279 clone = posix_acl_clone(acl, GFP_KERNEL);
280 error = -ENOMEM;
281 if (!clone)
282 goto cleanup;
283 mode = inode->i_mode;
284 error = posix_acl_create_masq(clone, &mode);
285 if (error >= 0) {
286 inode->i_mode = mode;
287 if (error > 0) {
288 /* This is an extended ACL */
289 error = ext2_set_acl(inode,
290 ACL_TYPE_ACCESS, clone);
291 }
292 }
293 posix_acl_release(clone);
294 }
295cleanup:
296 posix_acl_release(acl);
297 return error;
298}
299
300/*
301 * Does chmod for an inode that may have an Access Control List. The
302 * inode->i_mode field must be updated to the desired value by the caller
303 * before calling this function.
304 * Returns 0 on success, or a negative error number.
305 *
306 * We change the ACL rather than storing some ACL entries in the file
307 * mode permission bits (which would be more efficient), because that
308 * would break once additional permissions (like ACL_APPEND, ACL_DELETE
309 * for directories) are added. There are no more bits available in the
310 * file mode.
311 *
1b1dcc1b 312 * inode->i_mutex: down
1da177e4
LT
313 */
314int
315ext2_acl_chmod(struct inode *inode)
316{
317 struct posix_acl *acl, *clone;
318 int error;
319
320 if (!test_opt(inode->i_sb, POSIX_ACL))
321 return 0;
322 if (S_ISLNK(inode->i_mode))
323 return -EOPNOTSUPP;
324 acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
325 if (IS_ERR(acl) || !acl)
326 return PTR_ERR(acl);
327 clone = posix_acl_clone(acl, GFP_KERNEL);
328 posix_acl_release(acl);
329 if (!clone)
330 return -ENOMEM;
331 error = posix_acl_chmod_masq(clone, inode->i_mode);
332 if (!error)
333 error = ext2_set_acl(inode, ACL_TYPE_ACCESS, clone);
334 posix_acl_release(clone);
335 return error;
336}
337
338/*
339 * Extended attribut handlers
340 */
341static size_t
431547b3
CH
342ext2_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_size,
343 const char *name, size_t name_len, int type)
1da177e4 344{
9a59f452 345 const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
1da177e4 346
431547b3 347 if (!test_opt(dentry->d_sb, POSIX_ACL))
1da177e4
LT
348 return 0;
349 if (list && size <= list_size)
9a59f452 350 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
1da177e4
LT
351 return size;
352}
353
354static size_t
431547b3
CH
355ext2_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_size,
356 const char *name, size_t name_len, int type)
1da177e4 357{
9a59f452 358 const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
1da177e4 359
431547b3 360 if (!test_opt(dentry->d_sb, POSIX_ACL))
1da177e4
LT
361 return 0;
362 if (list && size <= list_size)
9a59f452 363 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
1da177e4
LT
364 return size;
365}
366
367static int
431547b3
CH
368ext2_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer,
369 size_t size, int type)
1da177e4
LT
370{
371 struct posix_acl *acl;
372 int error;
373
431547b3
CH
374 if (strcmp(name, "") != 0)
375 return -EINVAL;
376 if (!test_opt(dentry->d_sb, POSIX_ACL))
1da177e4
LT
377 return -EOPNOTSUPP;
378
431547b3 379 acl = ext2_get_acl(dentry->d_inode, type);
1da177e4
LT
380 if (IS_ERR(acl))
381 return PTR_ERR(acl);
382 if (acl == NULL)
383 return -ENODATA;
384 error = posix_acl_to_xattr(acl, buffer, size);
385 posix_acl_release(acl);
386
387 return error;
388}
389
390static int
431547b3
CH
391ext2_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
392 size_t size, int flags, int type)
1da177e4
LT
393{
394 struct posix_acl *acl;
395 int error;
396
431547b3
CH
397 if (strcmp(name, "") != 0)
398 return -EINVAL;
399 if (!test_opt(dentry->d_sb, POSIX_ACL))
1da177e4 400 return -EOPNOTSUPP;
431547b3 401 if (!is_owner_or_cap(dentry->d_inode))
1da177e4
LT
402 return -EPERM;
403
404 if (value) {
405 acl = posix_acl_from_xattr(value, size);
406 if (IS_ERR(acl))
407 return PTR_ERR(acl);
408 else if (acl) {
409 error = posix_acl_valid(acl);
410 if (error)
411 goto release_and_out;
412 }
413 } else
414 acl = NULL;
415
431547b3 416 error = ext2_set_acl(dentry->d_inode, type, acl);
1da177e4
LT
417
418release_and_out:
419 posix_acl_release(acl);
420 return error;
421}
422
749c72ef 423const struct xattr_handler ext2_xattr_acl_access_handler = {
9a59f452 424 .prefix = POSIX_ACL_XATTR_ACCESS,
431547b3 425 .flags = ACL_TYPE_ACCESS,
1da177e4 426 .list = ext2_xattr_list_acl_access,
431547b3
CH
427 .get = ext2_xattr_get_acl,
428 .set = ext2_xattr_set_acl,
1da177e4
LT
429};
430
749c72ef 431const struct xattr_handler ext2_xattr_acl_default_handler = {
9a59f452 432 .prefix = POSIX_ACL_XATTR_DEFAULT,
431547b3 433 .flags = ACL_TYPE_DEFAULT,
1da177e4 434 .list = ext2_xattr_list_acl_default,
431547b3
CH
435 .get = ext2_xattr_get_acl,
436 .set = ext2_xattr_set_acl,
1da177e4 437};