aboutsummaryrefslogtreecommitdiff
path: root/fs/btrfs/xattr.c
blob: af6246f36a9e5c318a335c09353093f99c8f7cc8 (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
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2007 Red Hat.  All rights reserved.
 */

#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 <linux/posix_acl_xattr.h>
#include <linux/iversion.h>
#include <linux/sched/mm.h>
#include "ctree.h"
#include "btrfs_inode.h"
#include "transaction.h"
#include "xattr.h"
#include "disk-io.h"
#include "props.h"
#include "locking.h"

int 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, btrfs_ino(BTRFS_I(inode)),
			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 btrfs_trans_handle *trans, struct inode *inode,
		   const char *name, const void *value, size_t size, int flags)
{
	struct btrfs_dir_item *di = NULL;
	struct btrfs_root *root = BTRFS_I(inode)->root;
	struct btrfs_fs_info *fs_info = root->fs_info;
	struct btrfs_path *path;
	size_t name_len = strlen(name);
	int ret = 0;

	ASSERT(trans);

	if (name_len + size > BTRFS_MAX_XATTR_SIZE(root->fs_info))
		return -ENOSPC;

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;
	path->skip_release_on_error = 1;

	if (!value) {
		di = btrfs_lookup_xattr(trans, root, path,
				btrfs_ino(BTRFS_I(inode)), name, name_len, -1);
		if (!di && (flags & XATTR_REPLACE))
			ret = -ENODATA;
		else if (IS_ERR(di))
			ret = PTR_ERR(di);
		else if (di)
			ret = btrfs_delete_one_dir_name(trans, root, path, di);
		goto out;
	}

	/*
	 * For a replace we can't just do the insert blindly.
	 * Do a lookup first (read-only btrfs_search_slot), and return if xattr
	 * doesn't exist. If it exists, fall down below to the insert/replace
	 * path - we can't race with a concurrent xattr delete, because the VFS
	 * locks the inode's i_mutex before calling setxattr or removexattr.
	 */
	if (flags & XATTR_REPLACE) {
		ASSERT(inode_is_locked(inode));
		di = btrfs_lookup_xattr(NULL, root, path,
				btrfs_ino(BTRFS_I(inode)), name, name_len, 0);
		if (!di)
			ret = -ENODATA;
		else if (IS_ERR(di))
			ret = PTR_ERR(di);
		if (ret)
			goto out;
		btrfs_release_path(path);
		di = NULL;
	}

	ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(BTRFS_I(inode)),
				      name, name_len, value, size);
	if (ret == -EOVERFLOW) {
		/*
		 * We have an existing item in a leaf, split_leaf couldn't
		 * expand it. That item might have or not a dir_item that
		 * matches our target xattr, so lets check.
		 */
		ret = 0;
		btrfs_assert_tree_locked(path->nodes[0]);
		di = btrfs_match_dir_item_name(fs_info, path, name, name_len);
		if (!di && !(flags & XATTR_REPLACE)) {
			ret = -ENOSPC;
			goto out;
		}
	} else if (ret == -EEXIST) {
		ret = 0;
		di = btrfs_match_dir_item_name(fs_info, path, name, name_len);
		ASSERT(di); /* logic error */
	} else if (ret) {
		goto out;
	}

	if (di && (flags & XATTR_CREATE)) {
		ret = -EEXIST;
		goto out;
	}

	if (di) {
		/*
		 * We're doing a replace, and it must be atomic, that is, at
		 * any point in time we have either the old or the new xattr
		 * value in the tree. We don't want readers (getxattr and
		 * listxattrs) to miss a value, this is specially important
		 * for ACLs.
		 */
		const int slot = path->slots[0];
		struct extent_buffer *leaf = path->nodes[0];
		const u16 old_data_len = btrfs_dir_data_len(leaf, di);
		const u32 item_size = btrfs_item_size_nr(leaf, slot);
		const u32 data_size = sizeof(*di) + name_len + size;
		struct btrfs_item *item;
		unsigned long data_ptr;
		char *ptr;

		if (size > old_data_len) {
			if (btrfs_leaf_free_space(leaf) <
			    (size - old_data_len)) {
				ret = -ENOSPC;
				goto out;
			}
		}

		if (old_data_len + name_len + sizeof(*di) == item_size) {
			/* No other xattrs packed in the same leaf item. */
			if (size > old_data_len)
				btrfs_extend_item(path, size - old_data_len);
			else if (size < old_data_len)
				btrfs_truncate_item(path, data_size, 1);
		} else {
			/* There are other xattrs packed in the same item. */
			ret = btrfs_delete_one_dir_name(trans, root, path, di);
			if (ret)
				goto out;
			btrfs_extend_item(path, data_size);
		}

		item = btrfs_item_nr(slot);
		ptr = btrfs_item_ptr(leaf, slot, char);
		ptr += btrfs_item_size(leaf, item) - data_size;
		di = (struct btrfs_dir_item *)ptr;
		btrfs_set_dir_data_len(leaf, di, size);
		data_ptr = ((unsigned long)(di + 1)) + name_len;
		write_extent_buffer(leaf, value, data_ptr, size);
		btrfs_mark_buffer_dirty(leaf);
	} else {
		/*
		 * Insert, and we had space for the xattr, so path->slots[0] is
		 * where our xattr dir_item is and btrfs_insert_xattr_item()
		 * filled it.
		 */
	}
out:
	btrfs_free_path(path);
	if (!ret) {
		set_bit(BTRFS_INODE_COPY_EVERYTHING,
			&BTRFS_I(inode)->runtime_flags);
		clear_bit(BTRFS_INODE_NO_XATTRS, &BTRFS_I(inode)->runtime_flags);
	}
	return ret;
}

/*
 * @value: "" makes the attribute to empty, NULL removes it
 */
int btrfs_setxattr_trans(struct inode *inode, const char *name,
			 const void *value, size_t size, int flags)
{
	struct btrfs_root *root = BTRFS_I(inode)->root;
	struct btrfs_trans_handle *trans;
	int ret;

	trans = btrfs_start_transaction(root, 2);
	if (IS_ERR(trans))
		return PTR_ERR(trans);

	ret = btrfs_setxattr(trans, inode, name, value, size, flags);
	if (ret)
		goto out;

	inode_inc_iversion(inode);
	inode->i_ctime = current_time(inode);
	ret = btrfs_update_inode(trans, root, BTRFS_I(inode));
	BUG_ON(ret);
out:
	btrfs_end_transaction(trans);
	return ret;
}

ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
{
	struct btrfs_key key;
	struct inode *inode = d_inode(dentry);
	struct btrfs_root *root = BTRFS_I(inode)->root;
	struct btrfs_path *path;
	int ret = 0;
	size_t total_size = 0, size_left = size;

	/*
	 * 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 = btrfs_ino(BTRFS_I(inode));
	key.type = BTRFS_XATTR_ITEM_KEY;
	key.offset = 0;

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

	/* search for our xattrs */
	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
	if (ret < 0)
		goto err;

	while (1) {
		struct extent_buffer *leaf;
		int slot;
		struct btrfs_dir_item *di;
		struct btrfs_key found_key;
		u32 item_size;
		u32 cur;

		leaf = path->nodes[0];
		slot = path->slots[0];

		/* this is where we start walking through the path */
		if (slot >= btrfs_header_nritems(leaf)) {
			/*
			 * if we've reached the last slot in this leaf we need
			 * to go to the next leaf and reset everything
			 */
			ret = btrfs_next_leaf(root, path);
			if (ret < 0)
				goto err;
			else if (ret > 0)
				break;
			continue;
		}

		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 (found_key.type > BTRFS_XATTR_ITEM_KEY)
			break;
		if (found_key.type < BTRFS_XATTR_ITEM_KEY)
			goto next_item;

		di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
		item_size = btrfs_item_size_nr(leaf, slot);
		cur = 0;
		while (cur < item_size) {
			u16 name_len = btrfs_dir_name_len(leaf, di);
			u16 data_len = btrfs_dir_data_len(leaf, di);
			u32 this_len = sizeof(*di) + name_len + data_len;
			unsigned long name_ptr = (unsigned long)(di + 1);

			total_size += name_len + 1;
			/*
			 * We are just looking for how big our buffer needs to
			 * be.
			 */
			if (!size)
				goto next;

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

			read_extent_buffer(leaf, buffer, name_ptr, name_len);
			buffer[name_len] = '\0';

			size_left -= name_len + 1;
			buffer += name_len + 1;
next:
			cur += this_len;
			di = (struct btrfs_dir_item *)((char *)di + this_len);
		}
next_item:
		path->slots[0]++;
	}
	ret = total_size;

err:
	btrfs_free_path(path);

	return ret;
}

static int btrfs_xattr_handler_get(const struct xattr_handler *handler,
				   struct dentry *unused, struct inode *inode,
				   const char *name, void *buffer, size_t size)
{
	name = xattr_full_name(handler, name);
	return btrfs_getxattr(inode, name, buffer, size);
}

static int btrfs_xattr_handler_set(const struct xattr_handler *handler,
				   struct dentry *unused, struct inode *inode,
				   const char *name, const void *buffer,
				   size_t size, int flags)
{
	name = xattr_full_name(handler, name);
	return btrfs_setxattr_trans(inode, name, buffer, size, flags);
}

static int btrfs_xattr_handler_set_prop(const struct xattr_handler *handler,
					struct dentry *unused, struct inode *inode,
					const char *name, const void *value,
					size_t size, int flags)
{
	int ret;
	struct btrfs_trans_handle *trans;
	struct btrfs_root *root = BTRFS_I(inode)->root;

	name = xattr_full_name(handler, name);
	ret = btrfs_validate_prop(name, value, size);
	if (ret)
		return ret;

	trans = btrfs_start_transaction(root, 2);
	if (IS_ERR(trans))
		return PTR_ERR(trans);

	ret = btrfs_set_prop(trans, inode, name, value, size, flags);
	if (!ret) {
		inode_inc_iversion(inode);
		inode->i_ctime = current_time(inode);
		ret = btrfs_update_inode(trans, root, BTRFS_I(inode));
		BUG_ON(ret);
	}

	btrfs_end_transaction(trans);

	return ret;
}

static const struct xattr_handler btrfs_security_xattr_handler = {
	.prefix = XATTR_SECURITY_PREFIX,
	.get = btrfs_xattr_handler_get,
	.set = btrfs_xattr_handler_set,
};

static const struct xattr_handler btrfs_trusted_xattr_handler = {
	.prefix = XATTR_TRUSTED_PREFIX,
	.get = btrfs_xattr_handler_get,
	.set = btrfs_xattr_handler_set,
};

static const struct xattr_handler btrfs_user_xattr_handler = {
	.prefix = XATTR_USER_PREFIX,
	.get = btrfs_xattr_handler_get,
	.set = btrfs_xattr_handler_set,
};

static const struct xattr_handler btrfs_btrfs_xattr_handler = {
	.prefix = XATTR_BTRFS_PREFIX,
	.get = btrfs_xattr_handler_get,
	.set = btrfs_xattr_handler_set_prop,
};

const struct xattr_handler *btrfs_xattr_handlers[] = {
	&btrfs_security_xattr_handler,
#ifdef CONFIG_BTRFS_FS_POSIX_ACL
	&posix_acl_access_xattr_handler,
	&posix_acl_default_xattr_handler,
#endif
	&btrfs_trusted_xattr_handler,
	&btrfs_user_xattr_handler,
	&btrfs_btrfs_xattr_handler,
	NULL,
};

static int btrfs_initxattrs(struct inode *inode,
			    const struct xattr *xattr_array, void *fs_private)
{
	struct btrfs_trans_handle *trans = fs_private;
	const struct xattr *xattr;
	unsigned int nofs_flag;
	char *name;
	int err = 0;

	/*
	 * We're holding a transaction handle, so use a NOFS memory allocation
	 * context to avoid deadlock if reclaim happens.
	 */
	nofs_flag = memalloc_nofs_save();
	for (xattr = xattr_array; xattr->name != NULL; xattr++) {
		name = kmalloc(XATTR_SECURITY_PREFIX_LEN +
			       strlen(xattr->name) + 1, GFP_KERNEL);
		if (!name) {
			err = -ENOMEM;
			break;
		}
		strcpy(name, XATTR_SECURITY_PREFIX);
		strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
		err = btrfs_setxattr(trans, inode, name, xattr->value,
				     xattr->value_len, 0);
		kfree(name);
		if (err < 0)
			break;
	}
	memalloc_nofs_restore(nofs_flag);
	return err;
}

int btrfs_xattr_security_init(struct btrfs_trans_handle *trans,
			      struct inode *inode, struct inode *dir,
			      const struct qstr *qstr)
{
	return security_inode_init_security(inode, dir, qstr,
					    &btrfs_initxattrs, trans);
}