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 */
134struct 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				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 */
246int
247ext3_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	}
277cleanup:
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 */
296int
297ext3_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;
314retry:
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;
327out:
328	posix_acl_release(acl);
329	return error;
330}
331
332/*
333 * Extended attribute handlers
334 */
335static size_t
336ext3_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
348static size_t
349ext3_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
361static int
362ext3_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
384static int
385ext3_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
412retry:
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
421release_and_out:
422	posix_acl_release(acl);
423	return error;
424}
425
426const 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
434const 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};