xattr_acl.c revision 098297b27d23ad9d0fc302e3417474d9342c6c14 
1#include <linux/capability.h>
2#include <linux/fs.h>
3#include <linux/posix_acl.h>
4#include "reiserfs.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 "xattr.h"
11#include "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
18
19int
20reiserfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
21{
22	int error, error2;
23	struct reiserfs_transaction_handle th;
24	size_t jcreate_blocks;
25	int size = acl ? posix_acl_xattr_size(acl->a_count) : 0;
26
27
28	/*
29	 * Pessimism: We can't assume that anything from the xattr root up
30	 * has been created.
31	 */
32
33	jcreate_blocks = reiserfs_xattr_jcreate_nblocks(inode) +
34			 reiserfs_xattr_nblocks(inode, size) * 2;
35
36	reiserfs_write_lock(inode->i_sb);
37	error = journal_begin(&th, inode->i_sb, jcreate_blocks);
38	reiserfs_write_unlock(inode->i_sb);
39	if (error == 0) {
40		error = __reiserfs_set_acl(&th, inode, type, acl);
41		reiserfs_write_lock(inode->i_sb);
42		error2 = journal_end(&th, inode->i_sb, jcreate_blocks);
43		reiserfs_write_unlock(inode->i_sb);
44		if (error2)
45			error = error2;
46	}
47
48	return error;
49}
50
51/*
52 * Convert from filesystem to in-memory representation.
53 */
54static struct posix_acl *reiserfs_posix_acl_from_disk(const void *value, size_t size)
55{
56	const char *end = (char *)value + size;
57	int n, count;
58	struct posix_acl *acl;
59
60	if (!value)
61		return NULL;
62	if (size < sizeof(reiserfs_acl_header))
63		return ERR_PTR(-EINVAL);
64	if (((reiserfs_acl_header *) value)->a_version !=
65	    cpu_to_le32(REISERFS_ACL_VERSION))
66		return ERR_PTR(-EINVAL);
67	value = (char *)value + sizeof(reiserfs_acl_header);
68	count = reiserfs_acl_count(size);
69	if (count < 0)
70		return ERR_PTR(-EINVAL);
71	if (count == 0)
72		return NULL;
73	acl = posix_acl_alloc(count, GFP_NOFS);
74	if (!acl)
75		return ERR_PTR(-ENOMEM);
76	for (n = 0; n < count; n++) {
77		reiserfs_acl_entry *entry = (reiserfs_acl_entry *) value;
78		if ((char *)value + sizeof(reiserfs_acl_entry_short) > end)
79			goto fail;
80		acl->a_entries[n].e_tag = le16_to_cpu(entry->e_tag);
81		acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
82		switch (acl->a_entries[n].e_tag) {
83		case ACL_USER_OBJ:
84		case ACL_GROUP_OBJ:
85		case ACL_MASK:
86		case ACL_OTHER:
87			value = (char *)value +
88			    sizeof(reiserfs_acl_entry_short);
89			break;
90
91		case ACL_USER:
92			value = (char *)value + sizeof(reiserfs_acl_entry);
93			if ((char *)value > end)
94				goto fail;
95			acl->a_entries[n].e_uid =
96				make_kuid(&init_user_ns,
97					  le32_to_cpu(entry->e_id));
98			break;
99		case ACL_GROUP:
100			value = (char *)value + sizeof(reiserfs_acl_entry);
101			if ((char *)value > end)
102				goto fail;
103			acl->a_entries[n].e_gid =
104				make_kgid(&init_user_ns,
105					  le32_to_cpu(entry->e_id));
106			break;
107
108		default:
109			goto fail;
110		}
111	}
112	if (value != end)
113		goto fail;
114	return acl;
115
116      fail:
117	posix_acl_release(acl);
118	return ERR_PTR(-EINVAL);
119}
120
121/*
122 * Convert from in-memory to filesystem representation.
123 */
124static void *reiserfs_posix_acl_to_disk(const struct posix_acl *acl, size_t * size)
125{
126	reiserfs_acl_header *ext_acl;
127	char *e;
128	int n;
129
130	*size = reiserfs_acl_size(acl->a_count);
131	ext_acl = kmalloc(sizeof(reiserfs_acl_header) +
132						  acl->a_count *
133						  sizeof(reiserfs_acl_entry),
134						  GFP_NOFS);
135	if (!ext_acl)
136		return ERR_PTR(-ENOMEM);
137	ext_acl->a_version = cpu_to_le32(REISERFS_ACL_VERSION);
138	e = (char *)ext_acl + sizeof(reiserfs_acl_header);
139	for (n = 0; n < acl->a_count; n++) {
140		const struct posix_acl_entry *acl_e = &acl->a_entries[n];
141		reiserfs_acl_entry *entry = (reiserfs_acl_entry *) e;
142		entry->e_tag = cpu_to_le16(acl->a_entries[n].e_tag);
143		entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
144		switch (acl->a_entries[n].e_tag) {
145		case ACL_USER:
146			entry->e_id = cpu_to_le32(
147				from_kuid(&init_user_ns, acl_e->e_uid));
148			e += sizeof(reiserfs_acl_entry);
149			break;
150		case ACL_GROUP:
151			entry->e_id = cpu_to_le32(
152				from_kgid(&init_user_ns, acl_e->e_gid));
153			e += sizeof(reiserfs_acl_entry);
154			break;
155
156		case ACL_USER_OBJ:
157		case ACL_GROUP_OBJ:
158		case ACL_MASK:
159		case ACL_OTHER:
160			e += sizeof(reiserfs_acl_entry_short);
161			break;
162
163		default:
164			goto fail;
165		}
166	}
167	return (char *)ext_acl;
168
169      fail:
170	kfree(ext_acl);
171	return ERR_PTR(-EINVAL);
172}
173
174/*
175 * Inode operation get_posix_acl().
176 *
177 * inode->i_mutex: down
178 * BKL held [before 2.5.x]
179 */
180struct posix_acl *reiserfs_get_acl(struct inode *inode, int type)
181{
182	char *name, *value;
183	struct posix_acl *acl;
184	int size;
185	int retval;
186
187	switch (type) {
188	case ACL_TYPE_ACCESS:
189		name = POSIX_ACL_XATTR_ACCESS;
190		break;
191	case ACL_TYPE_DEFAULT:
192		name = POSIX_ACL_XATTR_DEFAULT;
193		break;
194	default:
195		BUG();
196	}
197
198	size = reiserfs_xattr_get(inode, name, NULL, 0);
199	if (size < 0) {
200		if (size == -ENODATA || size == -ENOSYS) {
201			set_cached_acl(inode, type, NULL);
202			return NULL;
203		}
204		return ERR_PTR(size);
205	}
206
207	value = kmalloc(size, GFP_NOFS);
208	if (!value)
209		return ERR_PTR(-ENOMEM);
210
211	retval = reiserfs_xattr_get(inode, name, value, size);
212	if (retval == -ENODATA || retval == -ENOSYS) {
213		/*
214		 * This shouldn't actually happen as it should have
215		 * been caught above.. but just in case
216		 */
217		acl = NULL;
218	} else if (retval < 0) {
219		acl = ERR_PTR(retval);
220	} else {
221		acl = reiserfs_posix_acl_from_disk(value, retval);
222	}
223	if (!IS_ERR(acl))
224		set_cached_acl(inode, type, acl);
225
226	kfree(value);
227	return acl;
228}
229
230/*
231 * Inode operation set_posix_acl().
232 *
233 * inode->i_mutex: down
234 * BKL held [before 2.5.x]
235 */
236static int
237__reiserfs_set_acl(struct reiserfs_transaction_handle *th, struct inode *inode,
238		 int type, struct posix_acl *acl)
239{
240	char *name;
241	void *value = NULL;
242	size_t size = 0;
243	int error;
244
245	switch (type) {
246	case ACL_TYPE_ACCESS:
247		name = POSIX_ACL_XATTR_ACCESS;
248		if (acl) {
249			error = posix_acl_equiv_mode(acl, &inode->i_mode);
250			if (error < 0)
251				return error;
252			else {
253				if (error == 0)
254					acl = NULL;
255			}
256		}
257		break;
258	case ACL_TYPE_DEFAULT:
259		name = POSIX_ACL_XATTR_DEFAULT;
260		if (!S_ISDIR(inode->i_mode))
261			return acl ? -EACCES : 0;
262		break;
263	default:
264		return -EINVAL;
265	}
266
267	if (acl) {
268		value = reiserfs_posix_acl_to_disk(acl, &size);
269		if (IS_ERR(value))
270			return (int)PTR_ERR(value);
271	}
272
273	error = reiserfs_xattr_set_handle(th, inode, name, value, size, 0);
274
275	/*
276	 * Ensure that the inode gets dirtied if we're only using
277	 * the mode bits and an old ACL didn't exist. We don't need
278	 * to check if the inode is hashed here since we won't get
279	 * called by reiserfs_inherit_default_acl().
280	 */
281	if (error == -ENODATA) {
282		error = 0;
283		if (type == ACL_TYPE_ACCESS) {
284			inode->i_ctime = CURRENT_TIME_SEC;
285			mark_inode_dirty(inode);
286		}
287	}
288
289	kfree(value);
290
291	if (!error)
292		set_cached_acl(inode, type, acl);
293
294	return error;
295}
296
297/*
298 * dir->i_mutex: locked,
299 * inode is new and not released into the wild yet
300 */
301int
302reiserfs_inherit_default_acl(struct reiserfs_transaction_handle *th,
303			     struct inode *dir, struct dentry *dentry,
304			     struct inode *inode)
305{
306	struct posix_acl *default_acl, *acl;
307	int err = 0;
308
309	/* ACLs only get applied to files and directories */
310	if (S_ISLNK(inode->i_mode))
311		return 0;
312
313	/*
314	 * ACLs can only be used on "new" objects, so if it's an old object
315	 * there is nothing to inherit from
316	 */
317	if (get_inode_sd_version(dir) == STAT_DATA_V1)
318		goto apply_umask;
319
320	/*
321	 * Don't apply ACLs to objects in the .reiserfs_priv tree.. This
322	 * would be useless since permissions are ignored, and a pain because
323	 * it introduces locking cycles
324	 */
325	if (IS_PRIVATE(dir)) {
326		inode->i_flags |= S_PRIVATE;
327		goto apply_umask;
328	}
329
330	err = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
331	if (err)
332		return err;
333
334	if (default_acl) {
335		err = __reiserfs_set_acl(th, inode, ACL_TYPE_DEFAULT,
336					 default_acl);
337		posix_acl_release(default_acl);
338	}
339	if (acl) {
340		if (!err)
341			err = __reiserfs_set_acl(th, inode, ACL_TYPE_ACCESS,
342						 acl);
343		posix_acl_release(acl);
344	}
345
346	return err;
347
348      apply_umask:
349	/* no ACL, apply umask */
350	inode->i_mode &= ~current_umask();
351	return err;
352}
353
354/* This is used to cache the default acl before a new object is created.
355 * The biggest reason for this is to get an idea of how many blocks will
356 * actually be required for the create operation if we must inherit an ACL.
357 * An ACL write can add up to 3 object creations and an additional file write
358 * so we'd prefer not to reserve that many blocks in the journal if we can.
359 * It also has the advantage of not loading the ACL with a transaction open,
360 * this may seem silly, but if the owner of the directory is doing the
361 * creation, the ACL may not be loaded since the permissions wouldn't require
362 * it.
363 * We return the number of blocks required for the transaction.
364 */
365int reiserfs_cache_default_acl(struct inode *inode)
366{
367	struct posix_acl *acl;
368	int nblocks = 0;
369
370	if (IS_PRIVATE(inode))
371		return 0;
372
373	acl = reiserfs_get_acl(inode, ACL_TYPE_DEFAULT);
374
375	if (acl && !IS_ERR(acl)) {
376		int size = reiserfs_acl_size(acl->a_count);
377
378		/* Other xattrs can be created during inode creation. We don't
379		 * want to claim too many blocks, so we check to see if we
380		 * we need to create the tree to the xattrs, and then we
381		 * just want two files. */
382		nblocks = reiserfs_xattr_jcreate_nblocks(inode);
383		nblocks += JOURNAL_BLOCKS_PER_OBJECT(inode->i_sb);
384
385		REISERFS_I(inode)->i_flags |= i_has_xattr_dir;
386
387		/* We need to account for writes + bitmaps for two files */
388		nblocks += reiserfs_xattr_nblocks(inode, size) * 4;
389		posix_acl_release(acl);
390	}
391
392	return nblocks;
393}
394
395/*
396 * Called under i_mutex
397 */
398int reiserfs_acl_chmod(struct inode *inode)
399{
400	if (IS_PRIVATE(inode))
401		return 0;
402	if (get_inode_sd_version(inode) == STAT_DATA_V1 ||
403	    !reiserfs_posixacl(inode->i_sb))
404		return 0;
405
406	return posix_acl_chmod(inode, inode->i_mode);
407}
408