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1/*
2 * linux/fs/ext3/acl.c
3 *
4 * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
5 */
6
7#include "ext3.h"
8#include "xattr.h"
9#include "acl.h"
10
11/*
12 * Convert from filesystem to in-memory representation.
13 */
14static struct posix_acl *
15ext3_acl_from_disk(const void *value, size_t size)
16{
17 const char *end = (char *)value + size;
18 int n, count;
19 struct posix_acl *acl;
20
21 if (!value)
22 return NULL;
23 if (size < sizeof(ext3_acl_header))
24 return ERR_PTR(-EINVAL);
25 if (((ext3_acl_header *)value)->a_version !=
26 cpu_to_le32(EXT3_ACL_VERSION))
27 return ERR_PTR(-EINVAL);
28 value = (char *)value + sizeof(ext3_acl_header);
29 count = ext3_acl_count(size);
30 if (count < 0)
31 return ERR_PTR(-EINVAL);
32 if (count == 0)
33 return NULL;
34 acl = posix_acl_alloc(count, GFP_NOFS);
35 if (!acl)
36 return ERR_PTR(-ENOMEM);
37 for (n=0; n < count; n++) {
38 ext3_acl_entry *entry =
39 (ext3_acl_entry *)value;
40 if ((char *)value + sizeof(ext3_acl_entry_short) > end)
41 goto fail;
42 acl->a_entries[n].e_tag = le16_to_cpu(entry->e_tag);
43 acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
44 switch(acl->a_entries[n].e_tag) {
45 case ACL_USER_OBJ:
46 case ACL_GROUP_OBJ:
47 case ACL_MASK:
48 case ACL_OTHER:
49 value = (char *)value +
50 sizeof(ext3_acl_entry_short);
51 acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
52 break;
53
54 case ACL_USER:
55 case ACL_GROUP:
56 value = (char *)value + sizeof(ext3_acl_entry);
57 if ((char *)value > end)
58 goto fail;
59 acl->a_entries[n].e_id =
60 le32_to_cpu(entry->e_id);
61 break;
62
63 default:
64 goto fail;
65 }
66 }
67 if (value != end)
68 goto fail;
69 return acl;
70
71fail:
72 posix_acl_release(acl);
73 return ERR_PTR(-EINVAL);
74}
75
76/*
77 * Convert from in-memory to filesystem representation.
78 */
79static void *
80ext3_acl_to_disk(const struct posix_acl *acl, size_t *size)
81{
82 ext3_acl_header *ext_acl;
83 char *e;
84 size_t n;
85
86 *size = ext3_acl_size(acl->a_count);
87 ext_acl = kmalloc(sizeof(ext3_acl_header) + acl->a_count *
88 sizeof(ext3_acl_entry), GFP_NOFS);
89 if (!ext_acl)
90 return ERR_PTR(-ENOMEM);
91 ext_acl->a_version = cpu_to_le32(EXT3_ACL_VERSION);
92 e = (char *)ext_acl + sizeof(ext3_acl_header);
93 for (n=0; n < acl->a_count; n++) {
94 ext3_acl_entry *entry = (ext3_acl_entry *)e;
95 entry->e_tag = cpu_to_le16(acl->a_entries[n].e_tag);
96 entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
97 switch(acl->a_entries[n].e_tag) {
98 case ACL_USER:
99 case ACL_GROUP:
100 entry->e_id =
101 cpu_to_le32(acl->a_entries[n].e_id);
102 e += sizeof(ext3_acl_entry);
103 break;
104
105 case ACL_USER_OBJ:
106 case ACL_GROUP_OBJ:
107 case ACL_MASK:
108 case ACL_OTHER:
109 e += sizeof(ext3_acl_entry_short);
110 break;
111
112 default:
113 goto fail;
114 }
115 }
116 return (char *)ext_acl;
117
118fail:
119 kfree(ext_acl);
120 return ERR_PTR(-EINVAL);
121}
122
123/*
124 * Inode operation get_posix_acl().
125 *
126 * inode->i_mutex: don't care
127 */
128struct posix_acl *
129ext3_get_acl(struct inode *inode, int type)
130{
131 int name_index;
132 char *value = NULL;
133 struct posix_acl *acl;
134 int retval;
135
136 if (!test_opt(inode->i_sb, POSIX_ACL))
137 return NULL;
138
139 acl = get_cached_acl(inode, type);
140 if (acl != ACL_NOT_CACHED)
141 return acl;
142
143 switch (type) {
144 case ACL_TYPE_ACCESS:
145 name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
146 break;
147 case ACL_TYPE_DEFAULT:
148 name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
149 break;
150 default:
151 BUG();
152 }
153
154 retval = ext3_xattr_get(inode, name_index, "", NULL, 0);
155 if (retval > 0) {
156 value = kmalloc(retval, GFP_NOFS);
157 if (!value)
158 return ERR_PTR(-ENOMEM);
159 retval = ext3_xattr_get(inode, name_index, "", value, retval);
160 }
161 if (retval > 0)
162 acl = ext3_acl_from_disk(value, retval);
163 else if (retval == -ENODATA || retval == -ENOSYS)
164 acl = NULL;
165 else
166 acl = ERR_PTR(retval);
167 kfree(value);
168
169 if (!IS_ERR(acl))
170 set_cached_acl(inode, type, acl);
171
172 return acl;
173}
174
175/*
176 * Set the access or default ACL of an inode.
177 *
178 * inode->i_mutex: down unless called from ext3_new_inode
179 */
180static int
181ext3_set_acl(handle_t *handle, struct inode *inode, int type,
182 struct posix_acl *acl)
183{
184 int name_index;
185 void *value = NULL;
186 size_t size = 0;
187 int error;
188
189 if (S_ISLNK(inode->i_mode))
190 return -EOPNOTSUPP;
191
192 switch(type) {
193 case ACL_TYPE_ACCESS:
194 name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
195 if (acl) {
196 error = posix_acl_equiv_mode(acl, &inode->i_mode);
197 if (error < 0)
198 return error;
199 else {
200 inode->i_ctime = CURRENT_TIME_SEC;
201 ext3_mark_inode_dirty(handle, inode);
202 if (error == 0)
203 acl = NULL;
204 }
205 }
206 break;
207
208 case ACL_TYPE_DEFAULT:
209 name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
210 if (!S_ISDIR(inode->i_mode))
211 return acl ? -EACCES : 0;
212 break;
213
214 default:
215 return -EINVAL;
216 }
217 if (acl) {
218 value = ext3_acl_to_disk(acl, &size);
219 if (IS_ERR(value))
220 return (int)PTR_ERR(value);
221 }
222
223 error = ext3_xattr_set_handle(handle, inode, name_index, "",
224 value, size, 0);
225
226 kfree(value);
227
228 if (!error)
229 set_cached_acl(inode, type, acl);
230
231 return error;
232}
233
234/*
235 * Initialize the ACLs of a new inode. Called from ext3_new_inode.
236 *
237 * dir->i_mutex: down
238 * inode->i_mutex: up (access to inode is still exclusive)
239 */
240int
241ext3_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
242{
243 struct posix_acl *acl = NULL;
244 int error = 0;
245
246 if (!S_ISLNK(inode->i_mode)) {
247 if (test_opt(dir->i_sb, POSIX_ACL)) {
248 acl = ext3_get_acl(dir, ACL_TYPE_DEFAULT);
249 if (IS_ERR(acl))
250 return PTR_ERR(acl);
251 }
252 if (!acl)
253 inode->i_mode &= ~current_umask();
254 }
255 if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
256 if (S_ISDIR(inode->i_mode)) {
257 error = ext3_set_acl(handle, inode,
258 ACL_TYPE_DEFAULT, acl);
259 if (error)
260 goto cleanup;
261 }
262 error = posix_acl_create(&acl, GFP_NOFS, &inode->i_mode);
263 if (error < 0)
264 return error;
265
266 if (error > 0) {
267 /* This is an extended ACL */
268 error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, acl);
269 }
270 }
271cleanup:
272 posix_acl_release(acl);
273 return error;
274}
275
276/*
277 * Does chmod for an inode that may have an Access Control List. The
278 * inode->i_mode field must be updated to the desired value by the caller
279 * before calling this function.
280 * Returns 0 on success, or a negative error number.
281 *
282 * We change the ACL rather than storing some ACL entries in the file
283 * mode permission bits (which would be more efficient), because that
284 * would break once additional permissions (like ACL_APPEND, ACL_DELETE
285 * for directories) are added. There are no more bits available in the
286 * file mode.
287 *
288 * inode->i_mutex: down
289 */
290int
291ext3_acl_chmod(struct inode *inode)
292{
293 struct posix_acl *acl;
294 handle_t *handle;
295 int retries = 0;
296 int error;
297
298 if (S_ISLNK(inode->i_mode))
299 return -EOPNOTSUPP;
300 if (!test_opt(inode->i_sb, POSIX_ACL))
301 return 0;
302 acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
303 if (IS_ERR(acl) || !acl)
304 return PTR_ERR(acl);
305 error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
306 if (error)
307 return error;
308retry:
309 handle = ext3_journal_start(inode,
310 EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
311 if (IS_ERR(handle)) {
312 error = PTR_ERR(handle);
313 ext3_std_error(inode->i_sb, error);
314 goto out;
315 }
316 error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, acl);
317 ext3_journal_stop(handle);
318 if (error == -ENOSPC &&
319 ext3_should_retry_alloc(inode->i_sb, &retries))
320 goto retry;
321out:
322 posix_acl_release(acl);
323 return error;
324}
325
326/*
327 * Extended attribute handlers
328 */
329static size_t
330ext3_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_len,
331 const char *name, size_t name_len, int type)
332{
333 const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
334
335 if (!test_opt(dentry->d_sb, POSIX_ACL))
336 return 0;
337 if (list && size <= list_len)
338 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
339 return size;
340}
341
342static size_t
343ext3_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_len,
344 const char *name, size_t name_len, int type)
345{
346 const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
347
348 if (!test_opt(dentry->d_sb, POSIX_ACL))
349 return 0;
350 if (list && size <= list_len)
351 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
352 return size;
353}
354
355static int
356ext3_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer,
357 size_t size, int type)
358{
359 struct posix_acl *acl;
360 int error;
361
362 if (strcmp(name, "") != 0)
363 return -EINVAL;
364 if (!test_opt(dentry->d_sb, POSIX_ACL))
365 return -EOPNOTSUPP;
366
367 acl = ext3_get_acl(dentry->d_inode, type);
368 if (IS_ERR(acl))
369 return PTR_ERR(acl);
370 if (acl == NULL)
371 return -ENODATA;
372 error = posix_acl_to_xattr(acl, buffer, size);
373 posix_acl_release(acl);
374
375 return error;
376}
377
378static int
379ext3_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
380 size_t size, int flags, int type)
381{
382 struct inode *inode = dentry->d_inode;
383 handle_t *handle;
384 struct posix_acl *acl;
385 int error, retries = 0;
386
387 if (strcmp(name, "") != 0)
388 return -EINVAL;
389 if (!test_opt(inode->i_sb, POSIX_ACL))
390 return -EOPNOTSUPP;
391 if (!inode_owner_or_capable(inode))
392 return -EPERM;
393
394 if (value) {
395 acl = posix_acl_from_xattr(value, size);
396 if (IS_ERR(acl))
397 return PTR_ERR(acl);
398 else if (acl) {
399 error = posix_acl_valid(acl);
400 if (error)
401 goto release_and_out;
402 }
403 } else
404 acl = NULL;
405
406retry:
407 handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
408 if (IS_ERR(handle))
409 return PTR_ERR(handle);
410 error = ext3_set_acl(handle, inode, type, acl);
411 ext3_journal_stop(handle);
412 if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
413 goto retry;
414
415release_and_out:
416 posix_acl_release(acl);
417 return error;
418}
419
420const struct xattr_handler ext3_xattr_acl_access_handler = {
421 .prefix = POSIX_ACL_XATTR_ACCESS,
422 .flags = ACL_TYPE_ACCESS,
423 .list = ext3_xattr_list_acl_access,
424 .get = ext3_xattr_get_acl,
425 .set = ext3_xattr_set_acl,
426};
427
428const struct xattr_handler ext3_xattr_acl_default_handler = {
429 .prefix = POSIX_ACL_XATTR_DEFAULT,
430 .flags = ACL_TYPE_DEFAULT,
431 .list = ext3_xattr_list_acl_default,
432 .get = ext3_xattr_get_acl,
433 .set = ext3_xattr_set_acl,
434};