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 */
14 static struct posix_acl *
ext3_acl_from_disk(const void * value,size_t size)15 ext3_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 break;
52
53 case ACL_USER:
54 value = (char *)value + sizeof(ext3_acl_entry);
55 if ((char *)value > end)
56 goto fail;
57 acl->a_entries[n].e_uid =
58 make_kuid(&init_user_ns,
59 le32_to_cpu(entry->e_id));
60 break;
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_gid =
66 make_kgid(&init_user_ns,
67 le32_to_cpu(entry->e_id));
68 break;
69
70 default:
71 goto fail;
72 }
73 }
74 if (value != end)
75 goto fail;
76 return acl;
77
78 fail:
79 posix_acl_release(acl);
80 return ERR_PTR(-EINVAL);
81 }
82
83 /*
84 * Convert from in-memory to filesystem representation.
85 */
86 static void *
ext3_acl_to_disk(const struct posix_acl * acl,size_t * size)87 ext3_acl_to_disk(const struct posix_acl *acl, size_t *size)
88 {
89 ext3_acl_header *ext_acl;
90 char *e;
91 size_t n;
92
93 *size = ext3_acl_size(acl->a_count);
94 ext_acl = kmalloc(sizeof(ext3_acl_header) + acl->a_count *
95 sizeof(ext3_acl_entry), GFP_NOFS);
96 if (!ext_acl)
97 return ERR_PTR(-ENOMEM);
98 ext_acl->a_version = cpu_to_le32(EXT3_ACL_VERSION);
99 e = (char *)ext_acl + sizeof(ext3_acl_header);
100 for (n=0; n < acl->a_count; n++) {
101 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
102 ext3_acl_entry *entry = (ext3_acl_entry *)e;
103 entry->e_tag = cpu_to_le16(acl_e->e_tag);
104 entry->e_perm = cpu_to_le16(acl_e->e_perm);
105 switch(acl_e->e_tag) {
106 case ACL_USER:
107 entry->e_id = cpu_to_le32(
108 from_kuid(&init_user_ns, acl_e->e_uid));
109 e += sizeof(ext3_acl_entry);
110 break;
111 case ACL_GROUP:
112 entry->e_id = cpu_to_le32(
113 from_kgid(&init_user_ns, acl_e->e_gid));
114 e += sizeof(ext3_acl_entry);
115 break;
116
117 case ACL_USER_OBJ:
118 case ACL_GROUP_OBJ:
119 case ACL_MASK:
120 case ACL_OTHER:
121 e += sizeof(ext3_acl_entry_short);
122 break;
123
124 default:
125 goto fail;
126 }
127 }
128 return (char *)ext_acl;
129
130 fail:
131 kfree(ext_acl);
132 return ERR_PTR(-EINVAL);
133 }
134
135 /*
136 * Inode operation get_posix_acl().
137 *
138 * inode->i_mutex: don't care
139 */
140 struct posix_acl *
ext3_get_acl(struct inode * inode,int type)141 ext3_get_acl(struct inode *inode, int type)
142 {
143 int name_index;
144 char *value = NULL;
145 struct posix_acl *acl;
146 int retval;
147
148 if (!test_opt(inode->i_sb, POSIX_ACL))
149 return NULL;
150
151 acl = get_cached_acl(inode, type);
152 if (acl != ACL_NOT_CACHED)
153 return acl;
154
155 switch (type) {
156 case ACL_TYPE_ACCESS:
157 name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
158 break;
159 case ACL_TYPE_DEFAULT:
160 name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
161 break;
162 default:
163 BUG();
164 }
165
166 retval = ext3_xattr_get(inode, name_index, "", NULL, 0);
167 if (retval > 0) {
168 value = kmalloc(retval, GFP_NOFS);
169 if (!value)
170 return ERR_PTR(-ENOMEM);
171 retval = ext3_xattr_get(inode, name_index, "", value, retval);
172 }
173 if (retval > 0)
174 acl = ext3_acl_from_disk(value, retval);
175 else if (retval == -ENODATA || retval == -ENOSYS)
176 acl = NULL;
177 else
178 acl = ERR_PTR(retval);
179 kfree(value);
180
181 if (!IS_ERR(acl))
182 set_cached_acl(inode, type, acl);
183
184 return acl;
185 }
186
187 /*
188 * Set the access or default ACL of an inode.
189 *
190 * inode->i_mutex: down unless called from ext3_new_inode
191 */
192 static int
ext3_set_acl(handle_t * handle,struct inode * inode,int type,struct posix_acl * acl)193 ext3_set_acl(handle_t *handle, struct inode *inode, int type,
194 struct posix_acl *acl)
195 {
196 int name_index;
197 void *value = NULL;
198 size_t size = 0;
199 int error;
200
201 if (S_ISLNK(inode->i_mode))
202 return -EOPNOTSUPP;
203
204 switch(type) {
205 case ACL_TYPE_ACCESS:
206 name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
207 if (acl) {
208 error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
209 if (error)
210 return error;
211 inode->i_ctime = CURRENT_TIME_SEC;
212 ext3_mark_inode_dirty(handle, inode);
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 /*
243 * Initialize the ACLs of a new inode. Called from ext3_new_inode.
244 *
245 * dir->i_mutex: down
246 * inode->i_mutex: up (access to inode is still exclusive)
247 */
248 int
ext3_init_acl(handle_t * handle,struct inode * inode,struct inode * dir)249 ext3_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
250 {
251 struct posix_acl *acl = NULL;
252 int error = 0;
253
254 if (!S_ISLNK(inode->i_mode)) {
255 if (test_opt(dir->i_sb, POSIX_ACL)) {
256 acl = ext3_get_acl(dir, ACL_TYPE_DEFAULT);
257 if (IS_ERR(acl))
258 return PTR_ERR(acl);
259 }
260 if (!acl)
261 inode->i_mode &= ~current_umask();
262 }
263 if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
264 if (S_ISDIR(inode->i_mode)) {
265 error = ext3_set_acl(handle, inode,
266 ACL_TYPE_DEFAULT, acl);
267 if (error)
268 goto cleanup;
269 }
270 error = posix_acl_create(&acl, GFP_NOFS, &inode->i_mode);
271 if (error < 0)
272 return error;
273
274 if (error > 0) {
275 /* This is an extended ACL */
276 error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, acl);
277 }
278 }
279 cleanup:
280 posix_acl_release(acl);
281 return error;
282 }
283
284 /*
285 * Does chmod for an inode that may have an Access Control List. The
286 * inode->i_mode field must be updated to the desired value by the caller
287 * before calling this function.
288 * Returns 0 on success, or a negative error number.
289 *
290 * We change the ACL rather than storing some ACL entries in the file
291 * mode permission bits (which would be more efficient), because that
292 * would break once additional permissions (like ACL_APPEND, ACL_DELETE
293 * for directories) are added. There are no more bits available in the
294 * file mode.
295 *
296 * inode->i_mutex: down
297 */
298 int
ext3_acl_chmod(struct inode * inode)299 ext3_acl_chmod(struct inode *inode)
300 {
301 struct posix_acl *acl;
302 handle_t *handle;
303 int retries = 0;
304 int error;
305
306 if (S_ISLNK(inode->i_mode))
307 return -EOPNOTSUPP;
308 if (!test_opt(inode->i_sb, POSIX_ACL))
309 return 0;
310 acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
311 if (IS_ERR(acl) || !acl)
312 return PTR_ERR(acl);
313 error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
314 if (error)
315 return error;
316 retry:
317 handle = ext3_journal_start(inode,
318 EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
319 if (IS_ERR(handle)) {
320 error = PTR_ERR(handle);
321 ext3_std_error(inode->i_sb, error);
322 goto out;
323 }
324 error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, acl);
325 ext3_journal_stop(handle);
326 if (error == -ENOSPC &&
327 ext3_should_retry_alloc(inode->i_sb, &retries))
328 goto retry;
329 out:
330 posix_acl_release(acl);
331 return error;
332 }
333
334 /*
335 * Extended attribute handlers
336 */
337 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)338 ext3_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_len,
339 const char *name, size_t name_len, int type)
340 {
341 const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
342
343 if (!test_opt(dentry->d_sb, POSIX_ACL))
344 return 0;
345 if (list && size <= list_len)
346 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
347 return size;
348 }
349
350 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)351 ext3_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_len,
352 const char *name, size_t name_len, int type)
353 {
354 const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
355
356 if (!test_opt(dentry->d_sb, POSIX_ACL))
357 return 0;
358 if (list && size <= list_len)
359 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
360 return size;
361 }
362
363 static int
ext3_xattr_get_acl(struct dentry * dentry,const char * name,void * buffer,size_t size,int type)364 ext3_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer,
365 size_t size, int type)
366 {
367 struct posix_acl *acl;
368 int error;
369
370 if (strcmp(name, "") != 0)
371 return -EINVAL;
372 if (!test_opt(dentry->d_sb, POSIX_ACL))
373 return -EOPNOTSUPP;
374
375 acl = ext3_get_acl(dentry->d_inode, type);
376 if (IS_ERR(acl))
377 return PTR_ERR(acl);
378 if (acl == NULL)
379 return -ENODATA;
380 error = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
381 posix_acl_release(acl);
382
383 return error;
384 }
385
386 static int
ext3_xattr_set_acl(struct dentry * dentry,const char * name,const void * value,size_t size,int flags,int type)387 ext3_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
388 size_t size, int flags, int type)
389 {
390 struct inode *inode = dentry->d_inode;
391 handle_t *handle;
392 struct posix_acl *acl;
393 int error, retries = 0;
394
395 if (strcmp(name, "") != 0)
396 return -EINVAL;
397 if (!test_opt(inode->i_sb, POSIX_ACL))
398 return -EOPNOTSUPP;
399 if (!inode_owner_or_capable(inode))
400 return -EPERM;
401
402 if (value) {
403 acl = posix_acl_from_xattr(&init_user_ns, value, size);
404 if (IS_ERR(acl))
405 return PTR_ERR(acl);
406 else if (acl) {
407 error = posix_acl_valid(acl);
408 if (error)
409 goto release_and_out;
410 }
411 } else
412 acl = NULL;
413
414 retry:
415 handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
416 if (IS_ERR(handle))
417 return PTR_ERR(handle);
418 error = ext3_set_acl(handle, inode, type, acl);
419 ext3_journal_stop(handle);
420 if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
421 goto retry;
422
423 release_and_out:
424 posix_acl_release(acl);
425 return error;
426 }
427
428 const struct xattr_handler ext3_xattr_acl_access_handler = {
429 .prefix = POSIX_ACL_XATTR_ACCESS,
430 .flags = ACL_TYPE_ACCESS,
431 .list = ext3_xattr_list_acl_access,
432 .get = ext3_xattr_get_acl,
433 .set = ext3_xattr_set_acl,
434 };
435
436 const struct xattr_handler ext3_xattr_acl_default_handler = {
437 .prefix = POSIX_ACL_XATTR_DEFAULT,
438 .flags = ACL_TYPE_DEFAULT,
439 .list = ext3_xattr_list_acl_default,
440 .get = ext3_xattr_get_acl,
441 .set = ext3_xattr_set_acl,
442 };
443