xattr_acl.c revision d3fb612076eebec6f67257db0c7a9666ac7e5892 
1#include <linux/capability.h>
2#include <linux/fs.h>
3#include <linux/posix_acl.h>
4#include <linux/reiserfs_fs.h>
5#include <linux/errno.h>
6#include <linux/pagemap.h>
7#include <linux/xattr.h>
8#include <linux/slab.h>
9#include <linux/posix_acl_xattr.h>
10#include <linux/reiserfs_xattr.h>
11#include <linux/reiserfs_acl.h>
12#include <asm/uaccess.h>
13
14static int reiserfs_set_acl(struct reiserfs_transaction_handle *th,
15			    struct inode *inode, int type,
16			    struct posix_acl *acl);
17
18static int
19posix_acl_set(struct dentry *dentry, const char *name, const void *value,
20		size_t size, int flags, int type)
21{
22	struct inode *inode = dentry->d_inode;
23	struct posix_acl *acl;
24	int error, error2;
25	struct reiserfs_transaction_handle th;
26	size_t jcreate_blocks;
27	if (!reiserfs_posixacl(inode->i_sb))
28		return -EOPNOTSUPP;
29	if (!inode_owner_or_capable(inode))
30		return -EPERM;
31
32	if (value) {
33		acl = posix_acl_from_xattr(value, size);
34		if (IS_ERR(acl)) {
35			return PTR_ERR(acl);
36		} else if (acl) {
37			error = posix_acl_valid(acl);
38			if (error)
39				goto release_and_out;
40		}
41	} else
42		acl = NULL;
43
44	/* Pessimism: We can't assume that anything from the xattr root up
45	 * has been created. */
46
47	jcreate_blocks = reiserfs_xattr_jcreate_nblocks(inode) +
48			 reiserfs_xattr_nblocks(inode, size) * 2;
49
50	reiserfs_write_lock(inode->i_sb);
51	error = journal_begin(&th, inode->i_sb, jcreate_blocks);
52	if (error == 0) {
53		error = reiserfs_set_acl(&th, inode, type, acl);
54		error2 = journal_end(&th, inode->i_sb, jcreate_blocks);
55		if (error2)
56			error = error2;
57	}
58	reiserfs_write_unlock(inode->i_sb);
59
60      release_and_out:
61	posix_acl_release(acl);
62	return error;
63}
64
65static int
66posix_acl_get(struct dentry *dentry, const char *name, void *buffer,
67		size_t size, int type)
68{
69	struct posix_acl *acl;
70	int error;
71
72	if (!reiserfs_posixacl(dentry->d_sb))
73		return -EOPNOTSUPP;
74
75	acl = reiserfs_get_acl(dentry->d_inode, type);
76	if (IS_ERR(acl))
77		return PTR_ERR(acl);
78	if (acl == NULL)
79		return -ENODATA;
80	error = posix_acl_to_xattr(acl, buffer, size);
81	posix_acl_release(acl);
82
83	return error;
84}
85
86/*
87 * Convert from filesystem to in-memory representation.
88 */
89static struct posix_acl *posix_acl_from_disk(const void *value, size_t size)
90{
91	const char *end = (char *)value + size;
92	int n, count;
93	struct posix_acl *acl;
94
95	if (!value)
96		return NULL;
97	if (size < sizeof(reiserfs_acl_header))
98		return ERR_PTR(-EINVAL);
99	if (((reiserfs_acl_header *) value)->a_version !=
100	    cpu_to_le32(REISERFS_ACL_VERSION))
101		return ERR_PTR(-EINVAL);
102	value = (char *)value + sizeof(reiserfs_acl_header);
103	count = reiserfs_acl_count(size);
104	if (count < 0)
105		return ERR_PTR(-EINVAL);
106	if (count == 0)
107		return NULL;
108	acl = posix_acl_alloc(count, GFP_NOFS);
109	if (!acl)
110		return ERR_PTR(-ENOMEM);
111	for (n = 0; n < count; n++) {
112		reiserfs_acl_entry *entry = (reiserfs_acl_entry *) value;
113		if ((char *)value + sizeof(reiserfs_acl_entry_short) > end)
114			goto fail;
115		acl->a_entries[n].e_tag = le16_to_cpu(entry->e_tag);
116		acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
117		switch (acl->a_entries[n].e_tag) {
118		case ACL_USER_OBJ:
119		case ACL_GROUP_OBJ:
120		case ACL_MASK:
121		case ACL_OTHER:
122			value = (char *)value +
123			    sizeof(reiserfs_acl_entry_short);
124			acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
125			break;
126
127		case ACL_USER:
128		case ACL_GROUP:
129			value = (char *)value + sizeof(reiserfs_acl_entry);
130			if ((char *)value > end)
131				goto fail;
132			acl->a_entries[n].e_id = le32_to_cpu(entry->e_id);
133			break;
134
135		default:
136			goto fail;
137		}
138	}
139	if (value != end)
140		goto fail;
141	return acl;
142
143      fail:
144	posix_acl_release(acl);
145	return ERR_PTR(-EINVAL);
146}
147
148/*
149 * Convert from in-memory to filesystem representation.
150 */
151static void *posix_acl_to_disk(const struct posix_acl *acl, size_t * size)
152{
153	reiserfs_acl_header *ext_acl;
154	char *e;
155	int n;
156
157	*size = reiserfs_acl_size(acl->a_count);
158	ext_acl = kmalloc(sizeof(reiserfs_acl_header) +
159						  acl->a_count *
160						  sizeof(reiserfs_acl_entry),
161						  GFP_NOFS);
162	if (!ext_acl)
163		return ERR_PTR(-ENOMEM);
164	ext_acl->a_version = cpu_to_le32(REISERFS_ACL_VERSION);
165	e = (char *)ext_acl + sizeof(reiserfs_acl_header);
166	for (n = 0; n < acl->a_count; n++) {
167		reiserfs_acl_entry *entry = (reiserfs_acl_entry *) e;
168		entry->e_tag = cpu_to_le16(acl->a_entries[n].e_tag);
169		entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
170		switch (acl->a_entries[n].e_tag) {
171		case ACL_USER:
172		case ACL_GROUP:
173			entry->e_id = cpu_to_le32(acl->a_entries[n].e_id);
174			e += sizeof(reiserfs_acl_entry);
175			break;
176
177		case ACL_USER_OBJ:
178		case ACL_GROUP_OBJ:
179		case ACL_MASK:
180		case ACL_OTHER:
181			e += sizeof(reiserfs_acl_entry_short);
182			break;
183
184		default:
185			goto fail;
186		}
187	}
188	return (char *)ext_acl;
189
190      fail:
191	kfree(ext_acl);
192	return ERR_PTR(-EINVAL);
193}
194
195/*
196 * Inode operation get_posix_acl().
197 *
198 * inode->i_mutex: down
199 * BKL held [before 2.5.x]
200 */
201struct posix_acl *reiserfs_get_acl(struct inode *inode, int type)
202{
203	char *name, *value;
204	struct posix_acl *acl;
205	int size;
206	int retval;
207
208	acl = get_cached_acl(inode, type);
209	if (acl != ACL_NOT_CACHED)
210		return acl;
211
212	switch (type) {
213	case ACL_TYPE_ACCESS:
214		name = POSIX_ACL_XATTR_ACCESS;
215		break;
216	case ACL_TYPE_DEFAULT:
217		name = POSIX_ACL_XATTR_DEFAULT;
218		break;
219	default:
220		BUG();
221	}
222
223	size = reiserfs_xattr_get(inode, name, NULL, 0);
224	if (size < 0) {
225		if (size == -ENODATA || size == -ENOSYS) {
226			set_cached_acl(inode, type, NULL);
227			return NULL;
228		}
229		return ERR_PTR(size);
230	}
231
232	value = kmalloc(size, GFP_NOFS);
233	if (!value)
234		return ERR_PTR(-ENOMEM);
235
236	retval = reiserfs_xattr_get(inode, name, value, size);
237	if (retval == -ENODATA || retval == -ENOSYS) {
238		/* This shouldn't actually happen as it should have
239		   been caught above.. but just in case */
240		acl = NULL;
241	} else if (retval < 0) {
242		acl = ERR_PTR(retval);
243	} else {
244		acl = posix_acl_from_disk(value, retval);
245	}
246	if (!IS_ERR(acl))
247		set_cached_acl(inode, type, acl);
248
249	kfree(value);
250	return acl;
251}
252
253/*
254 * Inode operation set_posix_acl().
255 *
256 * inode->i_mutex: down
257 * BKL held [before 2.5.x]
258 */
259static int
260reiserfs_set_acl(struct reiserfs_transaction_handle *th, struct inode *inode,
261		 int type, struct posix_acl *acl)
262{
263	char *name;
264	void *value = NULL;
265	size_t size = 0;
266	int error;
267
268	if (S_ISLNK(inode->i_mode))
269		return -EOPNOTSUPP;
270
271	switch (type) {
272	case ACL_TYPE_ACCESS:
273		name = POSIX_ACL_XATTR_ACCESS;
274		if (acl) {
275			mode_t mode = inode->i_mode;
276			error = posix_acl_equiv_mode(acl, &mode);
277			if (error < 0)
278				return error;
279			else {
280				inode->i_mode = mode;
281				if (error == 0)
282					acl = NULL;
283			}
284		}
285		break;
286	case ACL_TYPE_DEFAULT:
287		name = POSIX_ACL_XATTR_DEFAULT;
288		if (!S_ISDIR(inode->i_mode))
289			return acl ? -EACCES : 0;
290		break;
291	default:
292		return -EINVAL;
293	}
294
295	if (acl) {
296		value = posix_acl_to_disk(acl, &size);
297		if (IS_ERR(value))
298			return (int)PTR_ERR(value);
299	}
300
301	error = reiserfs_xattr_set_handle(th, inode, name, value, size, 0);
302
303	/*
304	 * Ensure that the inode gets dirtied if we're only using
305	 * the mode bits and an old ACL didn't exist. We don't need
306	 * to check if the inode is hashed here since we won't get
307	 * called by reiserfs_inherit_default_acl().
308	 */
309	if (error == -ENODATA) {
310		error = 0;
311		if (type == ACL_TYPE_ACCESS) {
312			inode->i_ctime = CURRENT_TIME_SEC;
313			mark_inode_dirty(inode);
314		}
315	}
316
317	kfree(value);
318
319	if (!error)
320		set_cached_acl(inode, type, acl);
321
322	return error;
323}
324
325/* dir->i_mutex: locked,
326 * inode is new and not released into the wild yet */
327int
328reiserfs_inherit_default_acl(struct reiserfs_transaction_handle *th,
329			     struct inode *dir, struct dentry *dentry,
330			     struct inode *inode)
331{
332	struct posix_acl *acl;
333	int err = 0;
334
335	/* ACLs only get applied to files and directories */
336	if (S_ISLNK(inode->i_mode))
337		return 0;
338
339	/* ACLs can only be used on "new" objects, so if it's an old object
340	 * there is nothing to inherit from */
341	if (get_inode_sd_version(dir) == STAT_DATA_V1)
342		goto apply_umask;
343
344	/* Don't apply ACLs to objects in the .reiserfs_priv tree.. This
345	 * would be useless since permissions are ignored, and a pain because
346	 * it introduces locking cycles */
347	if (IS_PRIVATE(dir)) {
348		inode->i_flags |= S_PRIVATE;
349		goto apply_umask;
350	}
351
352	acl = reiserfs_get_acl(dir, ACL_TYPE_DEFAULT);
353	if (IS_ERR(acl))
354		return PTR_ERR(acl);
355
356	if (acl) {
357		/* Copy the default ACL to the default ACL of a new directory */
358		if (S_ISDIR(inode->i_mode)) {
359			err = reiserfs_set_acl(th, inode, ACL_TYPE_DEFAULT,
360					       acl);
361			if (err)
362				goto cleanup;
363		}
364
365		/* Now we reconcile the new ACL and the mode,
366		   potentially modifying both */
367		err = posix_acl_create(&acl, GFP_NOFS, &inode->i_mode);
368		if (err < 0)
369			return err;
370
371		/* If we need an ACL.. */
372		if (err > 0)
373			err = reiserfs_set_acl(th, inode, ACL_TYPE_ACCESS, acl);
374	      cleanup:
375		posix_acl_release(acl);
376	} else {
377	      apply_umask:
378		/* no ACL, apply umask */
379		inode->i_mode &= ~current_umask();
380	}
381
382	return err;
383}
384
385/* This is used to cache the default acl before a new object is created.
386 * The biggest reason for this is to get an idea of how many blocks will
387 * actually be required for the create operation if we must inherit an ACL.
388 * An ACL write can add up to 3 object creations and an additional file write
389 * so we'd prefer not to reserve that many blocks in the journal if we can.
390 * It also has the advantage of not loading the ACL with a transaction open,
391 * this may seem silly, but if the owner of the directory is doing the
392 * creation, the ACL may not be loaded since the permissions wouldn't require
393 * it.
394 * We return the number of blocks required for the transaction.
395 */
396int reiserfs_cache_default_acl(struct inode *inode)
397{
398	struct posix_acl *acl;
399	int nblocks = 0;
400
401	if (IS_PRIVATE(inode))
402		return 0;
403
404	acl = reiserfs_get_acl(inode, ACL_TYPE_DEFAULT);
405
406	if (acl && !IS_ERR(acl)) {
407		int size = reiserfs_acl_size(acl->a_count);
408
409		/* Other xattrs can be created during inode creation. We don't
410		 * want to claim too many blocks, so we check to see if we
411		 * we need to create the tree to the xattrs, and then we
412		 * just want two files. */
413		nblocks = reiserfs_xattr_jcreate_nblocks(inode);
414		nblocks += JOURNAL_BLOCKS_PER_OBJECT(inode->i_sb);
415
416		REISERFS_I(inode)->i_flags |= i_has_xattr_dir;
417
418		/* We need to account for writes + bitmaps for two files */
419		nblocks += reiserfs_xattr_nblocks(inode, size) * 4;
420		posix_acl_release(acl);
421	}
422
423	return nblocks;
424}
425
426int reiserfs_acl_chmod(struct inode *inode)
427{
428	struct reiserfs_transaction_handle th;
429	struct posix_acl *acl;
430	size_t size;
431	int depth;
432	int error;
433
434	if (S_ISLNK(inode->i_mode))
435		return -EOPNOTSUPP;
436
437	if (get_inode_sd_version(inode) == STAT_DATA_V1 ||
438	    !reiserfs_posixacl(inode->i_sb)) {
439		return 0;
440	}
441
442	reiserfs_write_unlock(inode->i_sb);
443	acl = reiserfs_get_acl(inode, ACL_TYPE_ACCESS);
444	reiserfs_write_lock(inode->i_sb);
445	if (!acl)
446		return 0;
447	if (IS_ERR(acl))
448		return PTR_ERR(acl);
449	error = posix_acl_chmod(&acl, GFP_NOFS, inode->i_mode);
450	if (error)
451		return error;
452
453	size = reiserfs_xattr_nblocks(inode, reiserfs_acl_size(acl->a_count));
454	depth = reiserfs_write_lock_once(inode->i_sb);
455	error = journal_begin(&th, inode->i_sb, size * 2);
456	if (!error) {
457		int error2;
458		error = reiserfs_set_acl(&th, inode, ACL_TYPE_ACCESS, acl);
459		error2 = journal_end(&th, inode->i_sb, size * 2);
460		if (error2)
461			error = error2;
462	}
463	reiserfs_write_unlock_once(inode->i_sb, depth);
464	posix_acl_release(acl);
465	return error;
466}
467
468static size_t posix_acl_access_list(struct dentry *dentry, char *list,
469				    size_t list_size, const char *name,
470				    size_t name_len, int type)
471{
472	const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
473	if (!reiserfs_posixacl(dentry->d_sb))
474		return 0;
475	if (list && size <= list_size)
476		memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
477	return size;
478}
479
480const struct xattr_handler reiserfs_posix_acl_access_handler = {
481	.prefix = POSIX_ACL_XATTR_ACCESS,
482	.flags = ACL_TYPE_ACCESS,
483	.get = posix_acl_get,
484	.set = posix_acl_set,
485	.list = posix_acl_access_list,
486};
487
488static size_t posix_acl_default_list(struct dentry *dentry, char *list,
489				     size_t list_size, const char *name,
490				     size_t name_len, int type)
491{
492	const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
493	if (!reiserfs_posixacl(dentry->d_sb))
494		return 0;
495	if (list && size <= list_size)
496		memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
497	return size;
498}
499
500const struct xattr_handler reiserfs_posix_acl_default_handler = {
501	.prefix = POSIX_ACL_XATTR_DEFAULT,
502	.flags = ACL_TYPE_DEFAULT,
503	.get = posix_acl_get,
504	.set = posix_acl_set,
505	.list = posix_acl_default_list,
506};
507