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 */
20static struct posix_acl *
21ext3_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
77fail:
78	posix_acl_release(acl);
79	return ERR_PTR(-EINVAL);
80}
81
82/*
83 * Convert from in-memory to filesystem representation.
84 */
85static void *
86ext3_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
124fail:
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 */
134static struct posix_acl *
135ext3_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 */
186static int
187ext3_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				mode_t mode = inode->i_mode;
203				error = posix_acl_equiv_mode(acl, &mode);
204				if (error < 0)
205					return error;
206				else {
207					inode->i_mode = mode;
208					inode->i_ctime = CURRENT_TIME_SEC;
209					ext3_mark_inode_dirty(handle, inode);
210					if (error == 0)
211						acl = NULL;
212				}
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
242int
243ext3_check_acl(struct inode *inode, int mask)
244{
245	struct posix_acl *acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
246
247	if (IS_ERR(acl))
248		return PTR_ERR(acl);
249	if (acl) {
250		int error = posix_acl_permission(inode, acl, mask);
251		posix_acl_release(acl);
252		return error;
253	}
254
255	return -EAGAIN;
256}
257
258/*
259 * Initialize the ACLs of a new inode. Called from ext3_new_inode.
260 *
261 * dir->i_mutex: down
262 * inode->i_mutex: up (access to inode is still exclusive)
263 */
264int
265ext3_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
266{
267	struct posix_acl *acl = NULL;
268	int error = 0;
269
270	if (!S_ISLNK(inode->i_mode)) {
271		if (test_opt(dir->i_sb, POSIX_ACL)) {
272			acl = ext3_get_acl(dir, ACL_TYPE_DEFAULT);
273			if (IS_ERR(acl))
274				return PTR_ERR(acl);
275		}
276		if (!acl)
277			inode->i_mode &= ~current_umask();
278	}
279	if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
280		struct posix_acl *clone;
281		mode_t mode;
282
283		if (S_ISDIR(inode->i_mode)) {
284			error = ext3_set_acl(handle, inode,
285					     ACL_TYPE_DEFAULT, acl);
286			if (error)
287				goto cleanup;
288		}
289		clone = posix_acl_clone(acl, GFP_NOFS);
290		error = -ENOMEM;
291		if (!clone)
292			goto cleanup;
293
294		mode = inode->i_mode;
295		error = posix_acl_create_masq(clone, &mode);
296		if (error >= 0) {
297			inode->i_mode = mode;
298			if (error > 0) {
299				/* This is an extended ACL */
300				error = ext3_set_acl(handle, inode,
301						     ACL_TYPE_ACCESS, clone);
302			}
303		}
304		posix_acl_release(clone);
305	}
306cleanup:
307	posix_acl_release(acl);
308	return error;
309}
310
311/*
312 * Does chmod for an inode that may have an Access Control List. The
313 * inode->i_mode field must be updated to the desired value by the caller
314 * before calling this function.
315 * Returns 0 on success, or a negative error number.
316 *
317 * We change the ACL rather than storing some ACL entries in the file
318 * mode permission bits (which would be more efficient), because that
319 * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
320 * for directories) are added. There are no more bits available in the
321 * file mode.
322 *
323 * inode->i_mutex: down
324 */
325int
326ext3_acl_chmod(struct inode *inode)
327{
328	struct posix_acl *acl, *clone;
329        int error;
330
331	if (S_ISLNK(inode->i_mode))
332		return -EOPNOTSUPP;
333	if (!test_opt(inode->i_sb, POSIX_ACL))
334		return 0;
335	acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
336	if (IS_ERR(acl) || !acl)
337		return PTR_ERR(acl);
338	clone = posix_acl_clone(acl, GFP_KERNEL);
339	posix_acl_release(acl);
340	if (!clone)
341		return -ENOMEM;
342	error = posix_acl_chmod_masq(clone, inode->i_mode);
343	if (!error) {
344		handle_t *handle;
345		int retries = 0;
346
347	retry:
348		handle = ext3_journal_start(inode,
349				EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
350		if (IS_ERR(handle)) {
351			error = PTR_ERR(handle);
352			ext3_std_error(inode->i_sb, error);
353			goto out;
354		}
355		error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, clone);
356		ext3_journal_stop(handle);
357		if (error == -ENOSPC &&
358		    ext3_should_retry_alloc(inode->i_sb, &retries))
359			goto retry;
360	}
361out:
362	posix_acl_release(clone);
363	return error;
364}
365
366/*
367 * Extended attribute handlers
368 */
369static size_t
370ext3_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_len,
371			   const char *name, size_t name_len, int type)
372{
373	const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
374
375	if (!test_opt(dentry->d_sb, POSIX_ACL))
376		return 0;
377	if (list && size <= list_len)
378		memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
379	return size;
380}
381
382static size_t
383ext3_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_len,
384			    const char *name, size_t name_len, int type)
385{
386	const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
387
388	if (!test_opt(dentry->d_sb, POSIX_ACL))
389		return 0;
390	if (list && size <= list_len)
391		memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
392	return size;
393}
394
395static int
396ext3_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer,
397		   size_t size, int type)
398{
399	struct posix_acl *acl;
400	int error;
401
402	if (strcmp(name, "") != 0)
403		return -EINVAL;
404	if (!test_opt(dentry->d_sb, POSIX_ACL))
405		return -EOPNOTSUPP;
406
407	acl = ext3_get_acl(dentry->d_inode, type);
408	if (IS_ERR(acl))
409		return PTR_ERR(acl);
410	if (acl == NULL)
411		return -ENODATA;
412	error = posix_acl_to_xattr(acl, buffer, size);
413	posix_acl_release(acl);
414
415	return error;
416}
417
418static int
419ext3_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
420		   size_t size, int flags, int type)
421{
422	struct inode *inode = dentry->d_inode;
423	handle_t *handle;
424	struct posix_acl *acl;
425	int error, retries = 0;
426
427	if (strcmp(name, "") != 0)
428		return -EINVAL;
429	if (!test_opt(inode->i_sb, POSIX_ACL))
430		return -EOPNOTSUPP;
431	if (!is_owner_or_cap(inode))
432		return -EPERM;
433
434	if (value) {
435		acl = posix_acl_from_xattr(value, size);
436		if (IS_ERR(acl))
437			return PTR_ERR(acl);
438		else if (acl) {
439			error = posix_acl_valid(acl);
440			if (error)
441				goto release_and_out;
442		}
443	} else
444		acl = NULL;
445
446retry:
447	handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
448	if (IS_ERR(handle))
449		return PTR_ERR(handle);
450	error = ext3_set_acl(handle, inode, type, acl);
451	ext3_journal_stop(handle);
452	if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
453		goto retry;
454
455release_and_out:
456	posix_acl_release(acl);
457	return error;
458}
459
460const struct xattr_handler ext3_xattr_acl_access_handler = {
461	.prefix	= POSIX_ACL_XATTR_ACCESS,
462	.flags	= ACL_TYPE_ACCESS,
463	.list	= ext3_xattr_list_acl_access,
464	.get	= ext3_xattr_get_acl,
465	.set	= ext3_xattr_set_acl,
466};
467
468const struct xattr_handler ext3_xattr_acl_default_handler = {
469	.prefix	= POSIX_ACL_XATTR_DEFAULT,
470	.flags	= ACL_TYPE_DEFAULT,
471	.list	= ext3_xattr_list_acl_default,
472	.get	= ext3_xattr_get_acl,
473	.set	= ext3_xattr_set_acl,
474};
475