summaryrefslogtreecommitdiff
path: root/fs/btrfs/xattr.c
blob: 312b9435e9f8005aaaf60cd09220f37699a40508 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
/*
 * Copyright (C) 2007 Red Hat.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License v2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#include <linux/init.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/rwsem.h>
#include <linux/xattr.h>
#include <linux/security.h>
#include "ctree.h"
#include "btrfs_inode.h"
#include "transaction.h"
#include "xattr.h"
#include "disk-io.h"


ssize_t __btrfs_getxattr(struct inode *inode, const char *name,
				void *buffer, size_t size)
{
	struct btrfs_dir_item *di;
	struct btrfs_root *root = BTRFS_I(inode)->root;
	struct btrfs_path *path;
	struct extent_buffer *leaf;
	int ret = 0;
	unsigned long data_ptr;

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

	/* lookup the xattr by name */
	di = btrfs_lookup_xattr(NULL, root, path, inode->i_ino, name,
				strlen(name), 0);
	if (!di) {
		ret = -ENODATA;
		goto out;
	} else if (IS_ERR(di)) {
		ret = PTR_ERR(di);
		goto out;
	}

	leaf = path->nodes[0];
	/* if size is 0, that means we want the size of the attr */
	if (!size) {
		ret = btrfs_dir_data_len(leaf, di);
		goto out;
	}

	/* now get the data out of our dir_item */
	if (btrfs_dir_data_len(leaf, di) > size) {
		ret = -ERANGE;
		goto out;
	}

	/*
	 * The way things are packed into the leaf is like this
	 * |struct btrfs_dir_item|name|data|
	 * where name is the xattr name, so security.foo, and data is the
	 * content of the xattr.  data_ptr points to the location in memory
	 * where the data starts in the in memory leaf
	 */
	data_ptr = (unsigned long)((char *)(di + 1) +
				   btrfs_dir_name_len(leaf, di));
	read_extent_buffer(leaf, buffer, data_ptr,
			   btrfs_dir_data_len(leaf, di));
	ret = btrfs_dir_data_len(leaf, di);

out:
	btrfs_free_path(path);
	return ret;
}

int __btrfs_setxattr(struct inode *inode, const char *name,
			    const void *value, size_t size, int flags)
{
	struct btrfs_dir_item *di;
	struct btrfs_root *root = BTRFS_I(inode)->root;
	struct btrfs_trans_handle *trans;
	struct btrfs_path *path;
	int ret = 0, mod = 0;

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

	trans = btrfs_start_transaction(root, 1);
	btrfs_set_trans_block_group(trans, inode);

	/* first lets see if we already have this xattr */
	di = btrfs_lookup_xattr(trans, root, path, inode->i_ino, name,
				strlen(name), -1);
	if (IS_ERR(di)) {
		ret = PTR_ERR(di);
		goto out;
	}

	/* ok we already have this xattr, lets remove it */
	if (di) {
		/* if we want create only exit */
		if (flags & XATTR_CREATE) {
			ret = -EEXIST;
			goto out;
		}

		ret = btrfs_delete_one_dir_name(trans, root, path, di);
		if (ret)
			goto out;
		btrfs_release_path(root, path);

		/* if we don't have a value then we are removing the xattr */
		if (!value) {
			mod = 1;
			goto out;
		}
	} else {
		btrfs_release_path(root, path);

		if (flags & XATTR_REPLACE) {
			/* we couldn't find the attr to replace */
			ret = -ENODATA;
			goto out;
		}
	}

	/* ok we have to create a completely new xattr */
	ret = btrfs_insert_xattr_item(trans, root, name, strlen(name),
				      value, size, inode->i_ino);
	if (ret)
		goto out;
	mod = 1;

out:
	if (mod) {
		inode->i_ctime = CURRENT_TIME;
		ret = btrfs_update_inode(trans, root, inode);
	}

	btrfs_end_transaction(trans, root);
	btrfs_free_path(path);
	return ret;
}

ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
{
	struct btrfs_key key, found_key;
	struct inode *inode = dentry->d_inode;
	struct btrfs_root *root = BTRFS_I(inode)->root;
	struct btrfs_path *path;
	struct btrfs_item *item;
	struct extent_buffer *leaf;
	struct btrfs_dir_item *di;
	int ret = 0, slot, advance;
	size_t total_size = 0, size_left = size;
	unsigned long name_ptr;
	size_t name_len;
	u32 nritems;

	/*
	 * ok we want all objects associated with this id.
	 * NOTE: we set key.offset = 0; because we want to start with the
	 * first xattr that we find and walk forward
	 */
	key.objectid = inode->i_ino;
	btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
	key.offset = 0;

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;
	path->reada = 2;

	/* search for our xattrs */
	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
	if (ret < 0)
		goto err;
	advance = 0;
	while (1) {
		leaf = path->nodes[0];
		nritems = btrfs_header_nritems(leaf);
		slot = path->slots[0];

		/* this is where we start walking through the path */
		if (advance || slot >= nritems) {
			/*
			 * if we've reached the last slot in this leaf we need
			 * to go to the next leaf and reset everything
			 */
			if (slot >= nritems-1) {
				ret = btrfs_next_leaf(root, path);
				if (ret)
					break;
				leaf = path->nodes[0];
				nritems = btrfs_header_nritems(leaf);
				slot = path->slots[0];
			} else {
				/*
				 * just walking through the slots on this leaf
				 */
				slot++;
				path->slots[0]++;
			}
		}
		advance = 1;

		item = btrfs_item_nr(leaf, slot);
		btrfs_item_key_to_cpu(leaf, &found_key, slot);

		/* check to make sure this item is what we want */
		if (found_key.objectid != key.objectid)
			break;
		if (btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY)
			break;

		di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);

		name_len = btrfs_dir_name_len(leaf, di);
		total_size += name_len + 1;

		/* we are just looking for how big our buffer needs to be */
		if (!size)
			continue;

		if (!buffer || (name_len + 1) > size_left) {
			ret = -ERANGE;
			goto err;
		}

		name_ptr = (unsigned long)(di + 1);
		read_extent_buffer(leaf, buffer, name_ptr, name_len);
		buffer[name_len] = '\0';

		size_left -= name_len + 1;
		buffer += name_len + 1;
	}
	ret = total_size;

err:
	btrfs_free_path(path);

	return ret;
}

/*
 * List of handlers for synthetic system.* attributes.  All real ondisk
 * attributes are handled directly.
 */
struct xattr_handler *btrfs_xattr_handlers[] = {
#ifdef CONFIG_FS_POSIX_ACL
	&btrfs_xattr_acl_access_handler,
	&btrfs_xattr_acl_default_handler,
#endif
	NULL,
};

/*
 * Check if the attribute is in a supported namespace.
 *
 * This applied after the check for the synthetic attributes in the system
 * namespace.
 */
static bool btrfs_is_valid_xattr(const char *name)
{
	return !strncmp(name, XATTR_SECURITY_PREFIX,
			XATTR_SECURITY_PREFIX_LEN) ||
	       !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN) ||
	       !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) ||
	       !strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN);
}

ssize_t btrfs_getxattr(struct dentry *dentry, const char *name,
		       void *buffer, size_t size)
{
	/*
	 * If this is a request for a synthetic attribute in the system.*
	 * namespace use the generic infrastructure to resolve a handler
	 * for it via sb->s_xattr.
	 */
	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
		return generic_getxattr(dentry, name, buffer, size);

	if (!btrfs_is_valid_xattr(name))
		return -EOPNOTSUPP;
	return __btrfs_getxattr(dentry->d_inode, name, buffer, size);
}

int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value,
		   size_t size, int flags)
{
	/*
	 * If this is a request for a synthetic attribute in the system.*
	 * namespace use the generic infrastructure to resolve a handler
	 * for it via sb->s_xattr.
	 */
	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
		return generic_setxattr(dentry, name, value, size, flags);

	if (!btrfs_is_valid_xattr(name))
		return -EOPNOTSUPP;

	if (size == 0)
		value = "";  /* empty EA, do not remove */
	return __btrfs_setxattr(dentry->d_inode, name, value, size, flags);
}

int btrfs_removexattr(struct dentry *dentry, const char *name)
{
	/*
	 * If this is a request for a synthetic attribute in the system.*
	 * namespace use the generic infrastructure to resolve a handler
	 * for it via sb->s_xattr.
	 */
	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
		return generic_removexattr(dentry, name);

	if (!btrfs_is_valid_xattr(name))
		return -EOPNOTSUPP;
	return __btrfs_setxattr(dentry->d_inode, name, NULL, 0, XATTR_REPLACE);
}

int btrfs_xattr_security_init(struct inode *inode, struct inode *dir)
{
	int err;
	size_t len;
	void *value;
	char *suffix;
	char *name;

	err = security_inode_init_security(inode, dir, &suffix, &value, &len);
	if (err) {
		if (err == -EOPNOTSUPP)
			return 0;
		return err;
	}

	name = kmalloc(XATTR_SECURITY_PREFIX_LEN + strlen(suffix) + 1,
		       GFP_NOFS);
	if (!name) {
		err = -ENOMEM;
	} else {
		strcpy(name, XATTR_SECURITY_PREFIX);
		strcpy(name + XATTR_SECURITY_PREFIX_LEN, suffix);
		err = __btrfs_setxattr(inode, name, value, len, 0);
		kfree(name);
	}

	kfree(suffix);
	kfree(value);
	return err;
}