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 *
ext3_acl_from_disk(const void * value,size_t size)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 *
ext3_acl_to_disk(const struct posix_acl * acl,size_t * size)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 struct posix_acl *
ext3_get_acl(struct inode * inode,int type)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
ext3_set_acl(handle_t * handle,struct inode * inode,int type,struct posix_acl * acl)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 error = posix_acl_equiv_mode(acl, &inode->i_mode);
203 if (error < 0)
204 return error;
205 else {
206 inode->i_ctime = CURRENT_TIME_SEC;
207 ext3_mark_inode_dirty(handle, inode);
208 if (error == 0)
209 acl = NULL;
210 }
211 }
212 break;
213
214 case ACL_TYPE_DEFAULT:
215 name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
216 if (!S_ISDIR(inode->i_mode))
217 return acl ? -EACCES : 0;
218 break;
219
220 default:
221 return -EINVAL;
222 }
223 if (acl) {
224 value = ext3_acl_to_disk(acl, &size);
225 if (IS_ERR(value))
226 return (int)PTR_ERR(value);
227 }
228
229 error = ext3_xattr_set_handle(handle, inode, name_index, "",
230 value, size, 0);
231
232 kfree(value);
233
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 ext3_new_inode.
242 *
243 * dir->i_mutex: down
244 * inode->i_mutex: up (access to inode is still exclusive)
245 */
246 int
ext3_init_acl(handle_t * handle,struct inode * inode,struct inode * dir)247 ext3_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 = ext3_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 = ext3_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 = ext3_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
ext3_acl_chmod(struct inode * inode)297 ext3_acl_chmod(struct inode *inode)
298 {
299 struct posix_acl *acl;
300 handle_t *handle;
301 int retries = 0;
302 int error;
303
304 if (S_ISLNK(inode->i_mode))
305 return -EOPNOTSUPP;
306 if (!test_opt(inode->i_sb, POSIX_ACL))
307 return 0;
308 acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
309 if (IS_ERR(acl) || !acl)
310 return PTR_ERR(acl);
311 error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
312 if (error)
313 return error;
314 retry:
315 handle = ext3_journal_start(inode,
316 EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
317 if (IS_ERR(handle)) {
318 error = PTR_ERR(handle);
319 ext3_std_error(inode->i_sb, error);
320 goto out;
321 }
322 error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, acl);
323 ext3_journal_stop(handle);
324 if (error == -ENOSPC &&
325 ext3_should_retry_alloc(inode->i_sb, &retries))
326 goto retry;
327 out:
328 posix_acl_release(acl);
329 return error;
330 }
331
332 /*
333 * Extended attribute handlers
334 */
335 static size_t
ext3_xattr_list_acl_access(struct dentry * dentry,char * list,size_t list_len,const char * name,size_t name_len,int type)336 ext3_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_len,
337 const char *name, size_t name_len, int type)
338 {
339 const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
340
341 if (!test_opt(dentry->d_sb, POSIX_ACL))
342 return 0;
343 if (list && size <= list_len)
344 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
345 return size;
346 }
347
348 static size_t
ext3_xattr_list_acl_default(struct dentry * dentry,char * list,size_t list_len,const char * name,size_t name_len,int type)349 ext3_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_len,
350 const char *name, size_t name_len, int type)
351 {
352 const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
353
354 if (!test_opt(dentry->d_sb, POSIX_ACL))
355 return 0;
356 if (list && size <= list_len)
357 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
358 return size;
359 }
360
361 static int
ext3_xattr_get_acl(struct dentry * dentry,const char * name,void * buffer,size_t size,int type)362 ext3_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer,
363 size_t size, int type)
364 {
365 struct posix_acl *acl;
366 int error;
367
368 if (strcmp(name, "") != 0)
369 return -EINVAL;
370 if (!test_opt(dentry->d_sb, POSIX_ACL))
371 return -EOPNOTSUPP;
372
373 acl = ext3_get_acl(dentry->d_inode, type);
374 if (IS_ERR(acl))
375 return PTR_ERR(acl);
376 if (acl == NULL)
377 return -ENODATA;
378 error = posix_acl_to_xattr(acl, buffer, size);
379 posix_acl_release(acl);
380
381 return error;
382 }
383
384 static int
ext3_xattr_set_acl(struct dentry * dentry,const char * name,const void * value,size_t size,int flags,int type)385 ext3_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
386 size_t size, int flags, int type)
387 {
388 struct inode *inode = dentry->d_inode;
389 handle_t *handle;
390 struct posix_acl *acl;
391 int error, retries = 0;
392
393 if (strcmp(name, "") != 0)
394 return -EINVAL;
395 if (!test_opt(inode->i_sb, POSIX_ACL))
396 return -EOPNOTSUPP;
397 if (!inode_owner_or_capable(inode))
398 return -EPERM;
399
400 if (value) {
401 acl = posix_acl_from_xattr(value, size);
402 if (IS_ERR(acl))
403 return PTR_ERR(acl);
404 else if (acl) {
405 error = posix_acl_valid(acl);
406 if (error)
407 goto release_and_out;
408 }
409 } else
410 acl = NULL;
411
412 retry:
413 handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
414 if (IS_ERR(handle))
415 return PTR_ERR(handle);
416 error = ext3_set_acl(handle, inode, type, acl);
417 ext3_journal_stop(handle);
418 if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
419 goto retry;
420
421 release_and_out:
422 posix_acl_release(acl);
423 return error;
424 }
425
426 const struct xattr_handler ext3_xattr_acl_access_handler = {
427 .prefix = POSIX_ACL_XATTR_ACCESS,
428 .flags = ACL_TYPE_ACCESS,
429 .list = ext3_xattr_list_acl_access,
430 .get = ext3_xattr_get_acl,
431 .set = ext3_xattr_set_acl,
432 };
433
434 const struct xattr_handler ext3_xattr_acl_default_handler = {
435 .prefix = POSIX_ACL_XATTR_DEFAULT,
436 .flags = ACL_TYPE_DEFAULT,
437 .list = ext3_xattr_list_acl_default,
438 .get = ext3_xattr_get_acl,
439 .set = ext3_xattr_set_acl,
440 };
441