xref: /openbmc/linux/fs/ext2/acl.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
1 /*
2  * linux/fs/ext2/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/fs.h>
11 #include "ext2.h"
12 #include "xattr.h"
13 #include "acl.h"
14 
15 /*
16  * Convert from filesystem to in-memory representation.
17  */
18 static struct posix_acl *
19 ext2_acl_from_disk(const void *value, size_t size)
20 {
21 	const char *end = (char *)value + size;
22 	int n, count;
23 	struct posix_acl *acl;
24 
25 	if (!value)
26 		return NULL;
27 	if (size < sizeof(ext2_acl_header))
28 		 return ERR_PTR(-EINVAL);
29 	if (((ext2_acl_header *)value)->a_version !=
30 	    cpu_to_le32(EXT2_ACL_VERSION))
31 		return ERR_PTR(-EINVAL);
32 	value = (char *)value + sizeof(ext2_acl_header);
33 	count = ext2_acl_count(size);
34 	if (count < 0)
35 		return ERR_PTR(-EINVAL);
36 	if (count == 0)
37 		return NULL;
38 	acl = posix_acl_alloc(count, GFP_KERNEL);
39 	if (!acl)
40 		return ERR_PTR(-ENOMEM);
41 	for (n=0; n < count; n++) {
42 		ext2_acl_entry *entry =
43 			(ext2_acl_entry *)value;
44 		if ((char *)value + sizeof(ext2_acl_entry_short) > end)
45 			goto fail;
46 		acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
47 		acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
48 		switch(acl->a_entries[n].e_tag) {
49 			case ACL_USER_OBJ:
50 			case ACL_GROUP_OBJ:
51 			case ACL_MASK:
52 			case ACL_OTHER:
53 				value = (char *)value +
54 					sizeof(ext2_acl_entry_short);
55 				acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
56 				break;
57 
58 			case ACL_USER:
59 			case ACL_GROUP:
60 				value = (char *)value + sizeof(ext2_acl_entry);
61 				if ((char *)value > end)
62 					goto fail;
63 				acl->a_entries[n].e_id =
64 					le32_to_cpu(entry->e_id);
65 				break;
66 
67 			default:
68 				goto fail;
69 		}
70 	}
71 	if (value != end)
72 		goto fail;
73 	return acl;
74 
75 fail:
76 	posix_acl_release(acl);
77 	return ERR_PTR(-EINVAL);
78 }
79 
80 /*
81  * Convert from in-memory to filesystem representation.
82  */
83 static void *
84 ext2_acl_to_disk(const struct posix_acl *acl, size_t *size)
85 {
86 	ext2_acl_header *ext_acl;
87 	char *e;
88 	size_t n;
89 
90 	*size = ext2_acl_size(acl->a_count);
91 	ext_acl = (ext2_acl_header *)kmalloc(sizeof(ext2_acl_header) +
92 		acl->a_count * sizeof(ext2_acl_entry), GFP_KERNEL);
93 	if (!ext_acl)
94 		return ERR_PTR(-ENOMEM);
95 	ext_acl->a_version = cpu_to_le32(EXT2_ACL_VERSION);
96 	e = (char *)ext_acl + sizeof(ext2_acl_header);
97 	for (n=0; n < acl->a_count; n++) {
98 		ext2_acl_entry *entry = (ext2_acl_entry *)e;
99 		entry->e_tag  = cpu_to_le16(acl->a_entries[n].e_tag);
100 		entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
101 		switch(acl->a_entries[n].e_tag) {
102 			case ACL_USER:
103 			case ACL_GROUP:
104 				entry->e_id =
105 					cpu_to_le32(acl->a_entries[n].e_id);
106 				e += sizeof(ext2_acl_entry);
107 				break;
108 
109 			case ACL_USER_OBJ:
110 			case ACL_GROUP_OBJ:
111 			case ACL_MASK:
112 			case ACL_OTHER:
113 				e += sizeof(ext2_acl_entry_short);
114 				break;
115 
116 			default:
117 				goto fail;
118 		}
119 	}
120 	return (char *)ext_acl;
121 
122 fail:
123 	kfree(ext_acl);
124 	return ERR_PTR(-EINVAL);
125 }
126 
127 static inline struct posix_acl *
128 ext2_iget_acl(struct inode *inode, struct posix_acl **i_acl)
129 {
130 	struct posix_acl *acl = EXT2_ACL_NOT_CACHED;
131 
132 	spin_lock(&inode->i_lock);
133 	if (*i_acl != EXT2_ACL_NOT_CACHED)
134 		acl = posix_acl_dup(*i_acl);
135 	spin_unlock(&inode->i_lock);
136 
137 	return acl;
138 }
139 
140 static inline void
141 ext2_iset_acl(struct inode *inode, struct posix_acl **i_acl,
142 		   struct posix_acl *acl)
143 {
144 	spin_lock(&inode->i_lock);
145 	if (*i_acl != EXT2_ACL_NOT_CACHED)
146 		posix_acl_release(*i_acl);
147 	*i_acl = posix_acl_dup(acl);
148 	spin_unlock(&inode->i_lock);
149 }
150 
151 /*
152  * inode->i_sem: don't care
153  */
154 static struct posix_acl *
155 ext2_get_acl(struct inode *inode, int type)
156 {
157 	struct ext2_inode_info *ei = EXT2_I(inode);
158 	int name_index;
159 	char *value = NULL;
160 	struct posix_acl *acl;
161 	int retval;
162 
163 	if (!test_opt(inode->i_sb, POSIX_ACL))
164 		return NULL;
165 
166 	switch(type) {
167 		case ACL_TYPE_ACCESS:
168 			acl = ext2_iget_acl(inode, &ei->i_acl);
169 			if (acl != EXT2_ACL_NOT_CACHED)
170 				return acl;
171 			name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
172 			break;
173 
174 		case ACL_TYPE_DEFAULT:
175 			acl = ext2_iget_acl(inode, &ei->i_default_acl);
176 			if (acl != EXT2_ACL_NOT_CACHED)
177 				return acl;
178 			name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
179 			break;
180 
181 		default:
182 			return ERR_PTR(-EINVAL);
183 	}
184 	retval = ext2_xattr_get(inode, name_index, "", NULL, 0);
185 	if (retval > 0) {
186 		value = kmalloc(retval, GFP_KERNEL);
187 		if (!value)
188 			return ERR_PTR(-ENOMEM);
189 		retval = ext2_xattr_get(inode, name_index, "", value, retval);
190 	}
191 	if (retval > 0)
192 		acl = ext2_acl_from_disk(value, retval);
193 	else if (retval == -ENODATA || retval == -ENOSYS)
194 		acl = NULL;
195 	else
196 		acl = ERR_PTR(retval);
197 	if (value)
198 		kfree(value);
199 
200 	if (!IS_ERR(acl)) {
201 		switch(type) {
202 			case ACL_TYPE_ACCESS:
203 				ext2_iset_acl(inode, &ei->i_acl, acl);
204 				break;
205 
206 			case ACL_TYPE_DEFAULT:
207 				ext2_iset_acl(inode, &ei->i_default_acl, acl);
208 				break;
209 		}
210 	}
211 	return acl;
212 }
213 
214 /*
215  * inode->i_sem: down
216  */
217 static int
218 ext2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
219 {
220 	struct ext2_inode_info *ei = EXT2_I(inode);
221 	int name_index;
222 	void *value = NULL;
223 	size_t size;
224 	int error;
225 
226 	if (S_ISLNK(inode->i_mode))
227 		return -EOPNOTSUPP;
228 	if (!test_opt(inode->i_sb, POSIX_ACL))
229 		return 0;
230 
231 	switch(type) {
232 		case ACL_TYPE_ACCESS:
233 			name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
234 			if (acl) {
235 				mode_t mode = inode->i_mode;
236 				error = posix_acl_equiv_mode(acl, &mode);
237 				if (error < 0)
238 					return error;
239 				else {
240 					inode->i_mode = mode;
241 					mark_inode_dirty(inode);
242 					if (error == 0)
243 						acl = NULL;
244 				}
245 			}
246 			break;
247 
248 		case ACL_TYPE_DEFAULT:
249 			name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
250 			if (!S_ISDIR(inode->i_mode))
251 				return acl ? -EACCES : 0;
252 			break;
253 
254 		default:
255 			return -EINVAL;
256 	}
257  	if (acl) {
258 		value = ext2_acl_to_disk(acl, &size);
259 		if (IS_ERR(value))
260 			return (int)PTR_ERR(value);
261 	}
262 
263 	error = ext2_xattr_set(inode, name_index, "", value, size, 0);
264 
265 	if (value)
266 		kfree(value);
267 	if (!error) {
268 		switch(type) {
269 			case ACL_TYPE_ACCESS:
270 				ext2_iset_acl(inode, &ei->i_acl, acl);
271 				break;
272 
273 			case ACL_TYPE_DEFAULT:
274 				ext2_iset_acl(inode, &ei->i_default_acl, acl);
275 				break;
276 		}
277 	}
278 	return error;
279 }
280 
281 static int
282 ext2_check_acl(struct inode *inode, int mask)
283 {
284 	struct posix_acl *acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
285 
286 	if (IS_ERR(acl))
287 		return PTR_ERR(acl);
288 	if (acl) {
289 		int error = posix_acl_permission(inode, acl, mask);
290 		posix_acl_release(acl);
291 		return error;
292 	}
293 
294 	return -EAGAIN;
295 }
296 
297 int
298 ext2_permission(struct inode *inode, int mask, struct nameidata *nd)
299 {
300 	return generic_permission(inode, mask, ext2_check_acl);
301 }
302 
303 /*
304  * Initialize the ACLs of a new inode. Called from ext2_new_inode.
305  *
306  * dir->i_sem: down
307  * inode->i_sem: up (access to inode is still exclusive)
308  */
309 int
310 ext2_init_acl(struct inode *inode, struct inode *dir)
311 {
312 	struct posix_acl *acl = NULL;
313 	int error = 0;
314 
315 	if (!S_ISLNK(inode->i_mode)) {
316 		if (test_opt(dir->i_sb, POSIX_ACL)) {
317 			acl = ext2_get_acl(dir, ACL_TYPE_DEFAULT);
318 			if (IS_ERR(acl))
319 				return PTR_ERR(acl);
320 		}
321 		if (!acl)
322 			inode->i_mode &= ~current->fs->umask;
323 	}
324 	if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
325                struct posix_acl *clone;
326 	       mode_t mode;
327 
328 		if (S_ISDIR(inode->i_mode)) {
329 			error = ext2_set_acl(inode, ACL_TYPE_DEFAULT, acl);
330 			if (error)
331 				goto cleanup;
332 		}
333 		clone = posix_acl_clone(acl, GFP_KERNEL);
334 		error = -ENOMEM;
335 		if (!clone)
336 			goto cleanup;
337 		mode = inode->i_mode;
338 		error = posix_acl_create_masq(clone, &mode);
339 		if (error >= 0) {
340 			inode->i_mode = mode;
341 			if (error > 0) {
342 				/* This is an extended ACL */
343 				error = ext2_set_acl(inode,
344 						     ACL_TYPE_ACCESS, clone);
345 			}
346 		}
347 		posix_acl_release(clone);
348 	}
349 cleanup:
350        posix_acl_release(acl);
351        return error;
352 }
353 
354 /*
355  * Does chmod for an inode that may have an Access Control List. The
356  * inode->i_mode field must be updated to the desired value by the caller
357  * before calling this function.
358  * Returns 0 on success, or a negative error number.
359  *
360  * We change the ACL rather than storing some ACL entries in the file
361  * mode permission bits (which would be more efficient), because that
362  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
363  * for directories) are added. There are no more bits available in the
364  * file mode.
365  *
366  * inode->i_sem: down
367  */
368 int
369 ext2_acl_chmod(struct inode *inode)
370 {
371 	struct posix_acl *acl, *clone;
372         int error;
373 
374 	if (!test_opt(inode->i_sb, POSIX_ACL))
375 		return 0;
376 	if (S_ISLNK(inode->i_mode))
377 		return -EOPNOTSUPP;
378 	acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
379 	if (IS_ERR(acl) || !acl)
380 		return PTR_ERR(acl);
381 	clone = posix_acl_clone(acl, GFP_KERNEL);
382 	posix_acl_release(acl);
383 	if (!clone)
384 		return -ENOMEM;
385 	error = posix_acl_chmod_masq(clone, inode->i_mode);
386 	if (!error)
387 		error = ext2_set_acl(inode, ACL_TYPE_ACCESS, clone);
388 	posix_acl_release(clone);
389 	return error;
390 }
391 
392 /*
393  * Extended attribut handlers
394  */
395 static size_t
396 ext2_xattr_list_acl_access(struct inode *inode, char *list, size_t list_size,
397 			   const char *name, size_t name_len)
398 {
399 	const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
400 
401 	if (!test_opt(inode->i_sb, POSIX_ACL))
402 		return 0;
403 	if (list && size <= list_size)
404 		memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
405 	return size;
406 }
407 
408 static size_t
409 ext2_xattr_list_acl_default(struct inode *inode, char *list, size_t list_size,
410 			    const char *name, size_t name_len)
411 {
412 	const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
413 
414 	if (!test_opt(inode->i_sb, POSIX_ACL))
415 		return 0;
416 	if (list && size <= list_size)
417 		memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
418 	return size;
419 }
420 
421 static int
422 ext2_xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size)
423 {
424 	struct posix_acl *acl;
425 	int error;
426 
427 	if (!test_opt(inode->i_sb, POSIX_ACL))
428 		return -EOPNOTSUPP;
429 
430 	acl = ext2_get_acl(inode, type);
431 	if (IS_ERR(acl))
432 		return PTR_ERR(acl);
433 	if (acl == NULL)
434 		return -ENODATA;
435 	error = posix_acl_to_xattr(acl, buffer, size);
436 	posix_acl_release(acl);
437 
438 	return error;
439 }
440 
441 static int
442 ext2_xattr_get_acl_access(struct inode *inode, const char *name,
443 			  void *buffer, size_t size)
444 {
445 	if (strcmp(name, "") != 0)
446 		return -EINVAL;
447 	return ext2_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
448 }
449 
450 static int
451 ext2_xattr_get_acl_default(struct inode *inode, const char *name,
452 			   void *buffer, size_t size)
453 {
454 	if (strcmp(name, "") != 0)
455 		return -EINVAL;
456 	return ext2_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
457 }
458 
459 static int
460 ext2_xattr_set_acl(struct inode *inode, int type, const void *value,
461 		   size_t size)
462 {
463 	struct posix_acl *acl;
464 	int error;
465 
466 	if (!test_opt(inode->i_sb, POSIX_ACL))
467 		return -EOPNOTSUPP;
468 	if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
469 		return -EPERM;
470 
471 	if (value) {
472 		acl = posix_acl_from_xattr(value, size);
473 		if (IS_ERR(acl))
474 			return PTR_ERR(acl);
475 		else if (acl) {
476 			error = posix_acl_valid(acl);
477 			if (error)
478 				goto release_and_out;
479 		}
480 	} else
481 		acl = NULL;
482 
483 	error = ext2_set_acl(inode, type, acl);
484 
485 release_and_out:
486 	posix_acl_release(acl);
487 	return error;
488 }
489 
490 static int
491 ext2_xattr_set_acl_access(struct inode *inode, const char *name,
492 			  const void *value, size_t size, int flags)
493 {
494 	if (strcmp(name, "") != 0)
495 		return -EINVAL;
496 	return ext2_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
497 }
498 
499 static int
500 ext2_xattr_set_acl_default(struct inode *inode, const char *name,
501 			   const void *value, size_t size, int flags)
502 {
503 	if (strcmp(name, "") != 0)
504 		return -EINVAL;
505 	return ext2_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
506 }
507 
508 struct xattr_handler ext2_xattr_acl_access_handler = {
509 	.prefix	= POSIX_ACL_XATTR_ACCESS,
510 	.list	= ext2_xattr_list_acl_access,
511 	.get	= ext2_xattr_get_acl_access,
512 	.set	= ext2_xattr_set_acl_access,
513 };
514 
515 struct xattr_handler ext2_xattr_acl_default_handler = {
516 	.prefix	= POSIX_ACL_XATTR_DEFAULT,
517 	.list	= ext2_xattr_list_acl_default,
518 	.get	= ext2_xattr_get_acl_default,
519 	.set	= ext2_xattr_set_acl_default,
520 };
521