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v6.8
  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (C) 2007 Red Hat.  All rights reserved.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  4 */
  5
  6#include <linux/init.h>
  7#include <linux/fs.h>
  8#include <linux/slab.h>
  9#include <linux/rwsem.h>
 10#include <linux/xattr.h>
 11#include <linux/security.h>
 12#include <linux/posix_acl_xattr.h>
 13#include <linux/iversion.h>
 14#include <linux/sched/mm.h>
 15#include "ctree.h"
 16#include "fs.h"
 17#include "messages.h"
 18#include "btrfs_inode.h"
 19#include "transaction.h"
 20#include "xattr.h"
 21#include "disk-io.h"
 22#include "props.h"
 23#include "locking.h"
 24#include "accessors.h"
 25#include "dir-item.h"
 26
 27int btrfs_getxattr(struct inode *inode, const char *name,
 
 28				void *buffer, size_t size)
 29{
 30	struct btrfs_dir_item *di;
 31	struct btrfs_root *root = BTRFS_I(inode)->root;
 32	struct btrfs_path *path;
 33	struct extent_buffer *leaf;
 34	int ret = 0;
 35	unsigned long data_ptr;
 36
 37	path = btrfs_alloc_path();
 38	if (!path)
 39		return -ENOMEM;
 40
 41	/* lookup the xattr by name */
 42	di = btrfs_lookup_xattr(NULL, root, path, btrfs_ino(BTRFS_I(inode)),
 43			name, strlen(name), 0);
 44	if (!di) {
 45		ret = -ENODATA;
 46		goto out;
 47	} else if (IS_ERR(di)) {
 48		ret = PTR_ERR(di);
 49		goto out;
 50	}
 51
 52	leaf = path->nodes[0];
 53	/* if size is 0, that means we want the size of the attr */
 54	if (!size) {
 55		ret = btrfs_dir_data_len(leaf, di);
 56		goto out;
 57	}
 58
 59	/* now get the data out of our dir_item */
 60	if (btrfs_dir_data_len(leaf, di) > size) {
 61		ret = -ERANGE;
 62		goto out;
 63	}
 64
 65	/*
 66	 * The way things are packed into the leaf is like this
 67	 * |struct btrfs_dir_item|name|data|
 68	 * where name is the xattr name, so security.foo, and data is the
 69	 * content of the xattr.  data_ptr points to the location in memory
 70	 * where the data starts in the in memory leaf
 71	 */
 72	data_ptr = (unsigned long)((char *)(di + 1) +
 73				   btrfs_dir_name_len(leaf, di));
 74	read_extent_buffer(leaf, buffer, data_ptr,
 75			   btrfs_dir_data_len(leaf, di));
 76	ret = btrfs_dir_data_len(leaf, di);
 77
 78out:
 79	btrfs_free_path(path);
 80	return ret;
 81}
 82
 83int btrfs_setxattr(struct btrfs_trans_handle *trans, struct inode *inode,
 84		   const char *name, const void *value, size_t size, int flags)
 
 85{
 86	struct btrfs_dir_item *di = NULL;
 87	struct btrfs_root *root = BTRFS_I(inode)->root;
 88	struct btrfs_fs_info *fs_info = root->fs_info;
 89	struct btrfs_path *path;
 90	size_t name_len = strlen(name);
 91	int ret = 0;
 92
 93	ASSERT(trans);
 94
 95	if (name_len + size > BTRFS_MAX_XATTR_SIZE(root->fs_info))
 96		return -ENOSPC;
 97
 98	path = btrfs_alloc_path();
 99	if (!path)
100		return -ENOMEM;
101	path->skip_release_on_error = 1;
102
103	if (!value) {
104		di = btrfs_lookup_xattr(trans, root, path,
105				btrfs_ino(BTRFS_I(inode)), name, name_len, -1);
106		if (!di && (flags & XATTR_REPLACE))
107			ret = -ENODATA;
108		else if (IS_ERR(di))
109			ret = PTR_ERR(di);
110		else if (di)
111			ret = btrfs_delete_one_dir_name(trans, root, path, di);
112		goto out;
113	}
114
115	/*
116	 * For a replace we can't just do the insert blindly.
117	 * Do a lookup first (read-only btrfs_search_slot), and return if xattr
118	 * doesn't exist. If it exists, fall down below to the insert/replace
119	 * path - we can't race with a concurrent xattr delete, because the VFS
120	 * locks the inode's i_mutex before calling setxattr or removexattr.
121	 */
122	if (flags & XATTR_REPLACE) {
123		ASSERT(inode_is_locked(inode));
124		di = btrfs_lookup_xattr(NULL, root, path,
125				btrfs_ino(BTRFS_I(inode)), name, name_len, 0);
126		if (!di)
127			ret = -ENODATA;
128		else if (IS_ERR(di))
129			ret = PTR_ERR(di);
 
 
 
 
 
 
130		if (ret)
131			goto out;
132		btrfs_release_path(path);
133		di = NULL;
134	}
135
136	ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(BTRFS_I(inode)),
137				      name, name_len, value, size);
138	if (ret == -EOVERFLOW) {
139		/*
140		 * We have an existing item in a leaf, split_leaf couldn't
141		 * expand it. That item might have or not a dir_item that
142		 * matches our target xattr, so lets check.
143		 */
144		ret = 0;
145		btrfs_assert_tree_write_locked(path->nodes[0]);
146		di = btrfs_match_dir_item_name(fs_info, path, name, name_len);
147		if (!di && !(flags & XATTR_REPLACE)) {
148			ret = -ENOSPC;
149			goto out;
150		}
151	} else if (ret == -EEXIST) {
152		ret = 0;
153		di = btrfs_match_dir_item_name(fs_info, path, name, name_len);
154		ASSERT(di); /* logic error */
155	} else if (ret) {
156		goto out;
157	}
158
159	if (di && (flags & XATTR_CREATE)) {
 
 
 
 
 
 
 
 
 
 
 
160		ret = -EEXIST;
161		goto out;
162	}
163
164	if (di) {
 
 
165		/*
166		 * We're doing a replace, and it must be atomic, that is, at
167		 * any point in time we have either the old or the new xattr
168		 * value in the tree. We don't want readers (getxattr and
169		 * listxattrs) to miss a value, this is specially important
170		 * for ACLs.
171		 */
172		const int slot = path->slots[0];
173		struct extent_buffer *leaf = path->nodes[0];
174		const u16 old_data_len = btrfs_dir_data_len(leaf, di);
175		const u32 item_size = btrfs_item_size(leaf, slot);
176		const u32 data_size = sizeof(*di) + name_len + size;
177		unsigned long data_ptr;
178		char *ptr;
179
180		if (size > old_data_len) {
181			if (btrfs_leaf_free_space(leaf) <
182			    (size - old_data_len)) {
183				ret = -ENOSPC;
184				goto out;
185			}
186		}
187
188		if (old_data_len + name_len + sizeof(*di) == item_size) {
189			/* No other xattrs packed in the same leaf item. */
190			if (size > old_data_len)
191				btrfs_extend_item(trans, path, size - old_data_len);
192			else if (size < old_data_len)
193				btrfs_truncate_item(trans, path, data_size, 1);
194		} else {
195			/* There are other xattrs packed in the same item. */
196			ret = btrfs_delete_one_dir_name(trans, root, path, di);
197			if (ret)
198				goto out;
199			btrfs_extend_item(trans, path, data_size);
200		}
201
202		ptr = btrfs_item_ptr(leaf, slot, char);
203		ptr += btrfs_item_size(leaf, slot) - data_size;
204		di = (struct btrfs_dir_item *)ptr;
205		btrfs_set_dir_data_len(leaf, di, size);
206		data_ptr = ((unsigned long)(di + 1)) + name_len;
207		write_extent_buffer(leaf, value, data_ptr, size);
208		btrfs_mark_buffer_dirty(trans, leaf);
209	} else {
210		/*
211		 * Insert, and we had space for the xattr, so path->slots[0] is
212		 * where our xattr dir_item is and btrfs_insert_xattr_item()
213		 * filled it.
214		 */
 
 
 
 
215	}
216out:
217	btrfs_free_path(path);
218	if (!ret) {
219		set_bit(BTRFS_INODE_COPY_EVERYTHING,
220			&BTRFS_I(inode)->runtime_flags);
221		clear_bit(BTRFS_INODE_NO_XATTRS, &BTRFS_I(inode)->runtime_flags);
222	}
223	return ret;
224}
225
226/*
227 * @value: "" makes the attribute to empty, NULL removes it
228 */
229int btrfs_setxattr_trans(struct inode *inode, const char *name,
230			 const void *value, size_t size, int flags)
 
231{
232	struct btrfs_root *root = BTRFS_I(inode)->root;
233	struct btrfs_trans_handle *trans;
234	const bool start_trans = (current->journal_info == NULL);
235	int ret;
236
237	if (start_trans) {
238		/*
239		 * 1 unit for inserting/updating/deleting the xattr
240		 * 1 unit for the inode item update
241		 */
242		trans = btrfs_start_transaction(root, 2);
243		if (IS_ERR(trans))
244			return PTR_ERR(trans);
245	} else {
246		/*
247		 * This can happen when smack is enabled and a directory is being
248		 * created. It happens through d_instantiate_new(), which calls
249		 * smack_d_instantiate(), which in turn calls __vfs_setxattr() to
250		 * set the transmute xattr (XATTR_NAME_SMACKTRANSMUTE) on the
251		 * inode. We have already reserved space for the xattr and inode
252		 * update at btrfs_mkdir(), so just use the transaction handle.
253		 * We don't join or start a transaction, as that will reset the
254		 * block_rsv of the handle and trigger a warning for the start
255		 * case.
256		 */
257		ASSERT(strncmp(name, XATTR_SECURITY_PREFIX,
258			       XATTR_SECURITY_PREFIX_LEN) == 0);
259		trans = current->journal_info;
260	}
261
262	ret = btrfs_setxattr(trans, inode, name, value, size, flags);
263	if (ret)
264		goto out;
265
266	inode_inc_iversion(inode);
267	inode_set_ctime_current(inode);
268	ret = btrfs_update_inode(trans, BTRFS_I(inode));
269	if (ret)
270		btrfs_abort_transaction(trans, ret);
271out:
272	if (start_trans)
273		btrfs_end_transaction(trans);
274	return ret;
275}
276
277ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
278{
279	struct btrfs_key found_key;
280	struct btrfs_key key;
281	struct inode *inode = d_inode(dentry);
282	struct btrfs_root *root = BTRFS_I(inode)->root;
283	struct btrfs_path *path;
284	int iter_ret = 0;
285	int ret = 0;
 
286	size_t total_size = 0, size_left = size;
 
 
287
288	/*
289	 * ok we want all objects associated with this id.
290	 * NOTE: we set key.offset = 0; because we want to start with the
291	 * first xattr that we find and walk forward
292	 */
293	key.objectid = btrfs_ino(BTRFS_I(inode));
294	key.type = BTRFS_XATTR_ITEM_KEY;
295	key.offset = 0;
296
297	path = btrfs_alloc_path();
298	if (!path)
299		return -ENOMEM;
300	path->reada = READA_FORWARD;
301
302	/* search for our xattrs */
303	btrfs_for_each_slot(root, &key, &found_key, path, iter_ret) {
304		struct extent_buffer *leaf;
305		int slot;
306		struct btrfs_dir_item *di;
307		u32 item_size;
308		u32 cur;
309
 
310		leaf = path->nodes[0];
311		slot = path->slots[0];
312
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
313		/* check to make sure this item is what we want */
314		if (found_key.objectid != key.objectid)
315			break;
316		if (found_key.type > BTRFS_XATTR_ITEM_KEY)
317			break;
318		if (found_key.type < BTRFS_XATTR_ITEM_KEY)
319			continue;
320
321		di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
322		item_size = btrfs_item_size(leaf, slot);
323		cur = 0;
324		while (cur < item_size) {
325			u16 name_len = btrfs_dir_name_len(leaf, di);
326			u16 data_len = btrfs_dir_data_len(leaf, di);
327			u32 this_len = sizeof(*di) + name_len + data_len;
328			unsigned long name_ptr = (unsigned long)(di + 1);
329
330			total_size += name_len + 1;
331			/*
332			 * We are just looking for how big our buffer needs to
333			 * be.
334			 */
335			if (!size)
336				goto next;
337
338			if (!buffer || (name_len + 1) > size_left) {
339			        iter_ret = -ERANGE;
340				break;
341			}
 
 
 
 
342
343			read_extent_buffer(leaf, buffer, name_ptr, name_len);
344			buffer[name_len] = '\0';
 
345
346			size_left -= name_len + 1;
347			buffer += name_len + 1;
348next:
349			cur += this_len;
350			di = (struct btrfs_dir_item *)((char *)di + this_len);
351		}
352	}
 
353
354	if (iter_ret < 0)
355		ret = iter_ret;
356	else
357		ret = total_size;
358
359	btrfs_free_path(path);
360
361	return ret;
362}
363
364static int btrfs_xattr_handler_get(const struct xattr_handler *handler,
365				   struct dentry *unused, struct inode *inode,
366				   const char *name, void *buffer, size_t size)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
367{
368	name = xattr_full_name(handler, name);
369	return btrfs_getxattr(inode, name, buffer, size);
 
 
 
370}
371
372static int btrfs_xattr_handler_set(const struct xattr_handler *handler,
373				   struct mnt_idmap *idmap,
374				   struct dentry *unused, struct inode *inode,
375				   const char *name, const void *buffer,
376				   size_t size, int flags)
377{
378	if (btrfs_root_readonly(BTRFS_I(inode)->root))
379		return -EROFS;
 
 
 
 
 
380
381	name = xattr_full_name(handler, name);
382	return btrfs_setxattr_trans(inode, name, buffer, size, flags);
 
383}
384
385static int btrfs_xattr_handler_get_security(const struct xattr_handler *handler,
386					    struct dentry *unused,
387					    struct inode *inode,
388					    const char *name, void *buffer,
389					    size_t size)
390{
391	int ret;
392	bool is_cap = false;
393
394	name = xattr_full_name(handler, name);
395
396	/*
397	 * security.capability doesn't cache the results, so calls into us
398	 * constantly to see if there's a capability xattr.  Cache the result
399	 * here in order to avoid wasting time doing lookups for xattrs we know
400	 * don't exist.
401	 */
402	if (strcmp(name, XATTR_NAME_CAPS) == 0) {
403		is_cap = true;
404		if (test_bit(BTRFS_INODE_NO_CAP_XATTR, &BTRFS_I(inode)->runtime_flags))
405			return -ENODATA;
406	}
407
408	ret = btrfs_getxattr(inode, name, buffer, size);
409	if (ret == -ENODATA && is_cap)
410		set_bit(BTRFS_INODE_NO_CAP_XATTR, &BTRFS_I(inode)->runtime_flags);
411	return ret;
412}
 
 
413
414static int btrfs_xattr_handler_set_security(const struct xattr_handler *handler,
415					    struct mnt_idmap *idmap,
416					    struct dentry *unused,
417					    struct inode *inode,
418					    const char *name,
419					    const void *buffer,
420					    size_t size, int flags)
421{
422	if (btrfs_root_readonly(BTRFS_I(inode)->root))
423		return -EROFS;
424
425	name = xattr_full_name(handler, name);
426	if (strcmp(name, XATTR_NAME_CAPS) == 0)
427		clear_bit(BTRFS_INODE_NO_CAP_XATTR, &BTRFS_I(inode)->runtime_flags);
428
429	return btrfs_setxattr_trans(inode, name, buffer, size, flags);
 
430}
431
432static int btrfs_xattr_handler_set_prop(const struct xattr_handler *handler,
433					struct mnt_idmap *idmap,
434					struct dentry *unused, struct inode *inode,
435					const char *name, const void *value,
436					size_t size, int flags)
437{
438	int ret;
439	struct btrfs_trans_handle *trans;
440	struct btrfs_root *root = BTRFS_I(inode)->root;
441
442	name = xattr_full_name(handler, name);
443	ret = btrfs_validate_prop(BTRFS_I(inode), name, value, size);
444	if (ret)
445		return ret;
446
447	if (btrfs_ignore_prop(BTRFS_I(inode), name))
448		return 0;
449
450	trans = btrfs_start_transaction(root, 2);
451	if (IS_ERR(trans))
452		return PTR_ERR(trans);
 
 
 
453
454	ret = btrfs_set_prop(trans, inode, name, value, size, flags);
455	if (!ret) {
456		inode_inc_iversion(inode);
457		inode_set_ctime_current(inode);
458		ret = btrfs_update_inode(trans, BTRFS_I(inode));
459		if (ret)
460			btrfs_abort_transaction(trans, ret);
461	}
462
463	btrfs_end_transaction(trans);
 
464
465	return ret;
 
466}
467
468static const struct xattr_handler btrfs_security_xattr_handler = {
469	.prefix = XATTR_SECURITY_PREFIX,
470	.get = btrfs_xattr_handler_get_security,
471	.set = btrfs_xattr_handler_set_security,
472};
473
474static const struct xattr_handler btrfs_trusted_xattr_handler = {
475	.prefix = XATTR_TRUSTED_PREFIX,
476	.get = btrfs_xattr_handler_get,
477	.set = btrfs_xattr_handler_set,
478};
479
480static const struct xattr_handler btrfs_user_xattr_handler = {
481	.prefix = XATTR_USER_PREFIX,
482	.get = btrfs_xattr_handler_get,
483	.set = btrfs_xattr_handler_set,
484};
485
486static const struct xattr_handler btrfs_btrfs_xattr_handler = {
487	.prefix = XATTR_BTRFS_PREFIX,
488	.get = btrfs_xattr_handler_get,
489	.set = btrfs_xattr_handler_set_prop,
490};
491
492const struct xattr_handler * const btrfs_xattr_handlers[] = {
493	&btrfs_security_xattr_handler,
494	&btrfs_trusted_xattr_handler,
495	&btrfs_user_xattr_handler,
496	&btrfs_btrfs_xattr_handler,
497	NULL,
498};
499
500static int btrfs_initxattrs(struct inode *inode,
501			    const struct xattr *xattr_array, void *fs_private)
502{
503	struct btrfs_trans_handle *trans = fs_private;
504	const struct xattr *xattr;
505	unsigned int nofs_flag;
506	char *name;
507	int err = 0;
508
509	/*
510	 * We're holding a transaction handle, so use a NOFS memory allocation
511	 * context to avoid deadlock if reclaim happens.
512	 */
513	nofs_flag = memalloc_nofs_save();
514	for (xattr = xattr_array; xattr->name != NULL; xattr++) {
515		name = kmalloc(XATTR_SECURITY_PREFIX_LEN +
516			       strlen(xattr->name) + 1, GFP_KERNEL);
517		if (!name) {
518			err = -ENOMEM;
519			break;
520		}
521		strcpy(name, XATTR_SECURITY_PREFIX);
522		strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
523
524		if (strcmp(name, XATTR_NAME_CAPS) == 0)
525			clear_bit(BTRFS_INODE_NO_CAP_XATTR, &BTRFS_I(inode)->runtime_flags);
526
527		err = btrfs_setxattr(trans, inode, name, xattr->value,
528				     xattr->value_len, 0);
529		kfree(name);
530		if (err < 0)
531			break;
532	}
533	memalloc_nofs_restore(nofs_flag);
534	return err;
535}
536
537int btrfs_xattr_security_init(struct btrfs_trans_handle *trans,
538			      struct inode *inode, struct inode *dir,
539			      const struct qstr *qstr)
540{
541	return security_inode_init_security(inode, dir, qstr,
542					    &btrfs_initxattrs, trans);
543}
v3.5.6
 
  1/*
  2 * Copyright (C) 2007 Red Hat.  All rights reserved.
  3 *
  4 * This program is free software; you can redistribute it and/or
  5 * modify it under the terms of the GNU General Public
  6 * License v2 as published by the Free Software Foundation.
  7 *
  8 * This program is distributed in the hope that it will be useful,
  9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 11 * General Public License for more details.
 12 *
 13 * You should have received a copy of the GNU General Public
 14 * License along with this program; if not, write to the
 15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 16 * Boston, MA 021110-1307, USA.
 17 */
 18
 19#include <linux/init.h>
 20#include <linux/fs.h>
 21#include <linux/slab.h>
 22#include <linux/rwsem.h>
 23#include <linux/xattr.h>
 24#include <linux/security.h>
 
 
 
 25#include "ctree.h"
 
 
 26#include "btrfs_inode.h"
 27#include "transaction.h"
 28#include "xattr.h"
 29#include "disk-io.h"
 
 
 
 
 30
 31
 32ssize_t __btrfs_getxattr(struct inode *inode, const char *name,
 33				void *buffer, size_t size)
 34{
 35	struct btrfs_dir_item *di;
 36	struct btrfs_root *root = BTRFS_I(inode)->root;
 37	struct btrfs_path *path;
 38	struct extent_buffer *leaf;
 39	int ret = 0;
 40	unsigned long data_ptr;
 41
 42	path = btrfs_alloc_path();
 43	if (!path)
 44		return -ENOMEM;
 45
 46	/* lookup the xattr by name */
 47	di = btrfs_lookup_xattr(NULL, root, path, btrfs_ino(inode), name,
 48				strlen(name), 0);
 49	if (!di) {
 50		ret = -ENODATA;
 51		goto out;
 52	} else if (IS_ERR(di)) {
 53		ret = PTR_ERR(di);
 54		goto out;
 55	}
 56
 57	leaf = path->nodes[0];
 58	/* if size is 0, that means we want the size of the attr */
 59	if (!size) {
 60		ret = btrfs_dir_data_len(leaf, di);
 61		goto out;
 62	}
 63
 64	/* now get the data out of our dir_item */
 65	if (btrfs_dir_data_len(leaf, di) > size) {
 66		ret = -ERANGE;
 67		goto out;
 68	}
 69
 70	/*
 71	 * The way things are packed into the leaf is like this
 72	 * |struct btrfs_dir_item|name|data|
 73	 * where name is the xattr name, so security.foo, and data is the
 74	 * content of the xattr.  data_ptr points to the location in memory
 75	 * where the data starts in the in memory leaf
 76	 */
 77	data_ptr = (unsigned long)((char *)(di + 1) +
 78				   btrfs_dir_name_len(leaf, di));
 79	read_extent_buffer(leaf, buffer, data_ptr,
 80			   btrfs_dir_data_len(leaf, di));
 81	ret = btrfs_dir_data_len(leaf, di);
 82
 83out:
 84	btrfs_free_path(path);
 85	return ret;
 86}
 87
 88static int do_setxattr(struct btrfs_trans_handle *trans,
 89		       struct inode *inode, const char *name,
 90		       const void *value, size_t size, int flags)
 91{
 92	struct btrfs_dir_item *di;
 93	struct btrfs_root *root = BTRFS_I(inode)->root;
 
 94	struct btrfs_path *path;
 95	size_t name_len = strlen(name);
 96	int ret = 0;
 97
 98	if (name_len + size > BTRFS_MAX_XATTR_SIZE(root))
 
 
 99		return -ENOSPC;
100
101	path = btrfs_alloc_path();
102	if (!path)
103		return -ENOMEM;
 
 
 
 
 
 
 
 
 
 
 
 
 
104
 
 
 
 
 
 
 
105	if (flags & XATTR_REPLACE) {
106		di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode), name,
107					name_len, -1);
108		if (IS_ERR(di)) {
 
 
 
109			ret = PTR_ERR(di);
110			goto out;
111		} else if (!di) {
112			ret = -ENODATA;
113			goto out;
114		}
115		ret = btrfs_delete_one_dir_name(trans, root, path, di);
116		if (ret)
117			goto out;
118		btrfs_release_path(path);
 
 
119
 
 
 
120		/*
121		 * remove the attribute
 
 
122		 */
123		if (!value)
 
 
 
 
124			goto out;
 
 
 
 
 
 
 
125	}
126
127again:
128	ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(inode),
129				      name, name_len, value, size);
130	/*
131	 * If we're setting an xattr to a new value but the new value is say
132	 * exactly BTRFS_MAX_XATTR_SIZE, we could end up with EOVERFLOW getting
133	 * back from split_leaf.  This is because it thinks we'll be extending
134	 * the existing item size, but we're asking for enough space to add the
135	 * item itself.  So if we get EOVERFLOW just set ret to EEXIST and let
136	 * the rest of the function figure it out.
137	 */
138	if (ret == -EOVERFLOW)
139		ret = -EEXIST;
 
 
140
141	if (ret == -EEXIST) {
142		if (flags & XATTR_CREATE)
143			goto out;
144		/*
145		 * We can't use the path we already have since we won't have the
146		 * proper locking for a delete, so release the path and
147		 * re-lookup to delete the thing.
 
 
148		 */
149		btrfs_release_path(path);
150		di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode),
151					name, name_len, -1);
152		if (IS_ERR(di)) {
153			ret = PTR_ERR(di);
154			goto out;
155		} else if (!di) {
156			/* Shouldn't happen but just in case... */
157			btrfs_release_path(path);
158			goto again;
 
 
 
 
159		}
160
161		ret = btrfs_delete_one_dir_name(trans, root, path, di);
162		if (ret)
163			goto out;
 
 
 
 
 
 
 
 
 
 
164
 
 
 
 
 
 
 
 
165		/*
166		 * We have a value to set, so go back and try to insert it now.
 
 
167		 */
168		if (value) {
169			btrfs_release_path(path);
170			goto again;
171		}
172	}
173out:
174	btrfs_free_path(path);
 
 
 
 
 
175	return ret;
176}
177
178/*
179 * @value: "" makes the attribute to empty, NULL removes it
180 */
181int __btrfs_setxattr(struct btrfs_trans_handle *trans,
182		     struct inode *inode, const char *name,
183		     const void *value, size_t size, int flags)
184{
185	struct btrfs_root *root = BTRFS_I(inode)->root;
 
 
186	int ret;
187
188	if (trans)
189		return do_setxattr(trans, inode, name, value, size, flags);
190
191	trans = btrfs_start_transaction(root, 2);
192	if (IS_ERR(trans))
193		return PTR_ERR(trans);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
194
195	ret = do_setxattr(trans, inode, name, value, size, flags);
196	if (ret)
197		goto out;
198
199	inode_inc_iversion(inode);
200	inode->i_ctime = CURRENT_TIME;
201	ret = btrfs_update_inode(trans, root, inode);
202	BUG_ON(ret);
 
203out:
204	btrfs_end_transaction(trans, root);
 
205	return ret;
206}
207
208ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
209{
210	struct btrfs_key key, found_key;
211	struct inode *inode = dentry->d_inode;
 
212	struct btrfs_root *root = BTRFS_I(inode)->root;
213	struct btrfs_path *path;
214	struct extent_buffer *leaf;
215	struct btrfs_dir_item *di;
216	int ret = 0, slot;
217	size_t total_size = 0, size_left = size;
218	unsigned long name_ptr;
219	size_t name_len;
220
221	/*
222	 * ok we want all objects associated with this id.
223	 * NOTE: we set key.offset = 0; because we want to start with the
224	 * first xattr that we find and walk forward
225	 */
226	key.objectid = btrfs_ino(inode);
227	btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
228	key.offset = 0;
229
230	path = btrfs_alloc_path();
231	if (!path)
232		return -ENOMEM;
233	path->reada = 2;
234
235	/* search for our xattrs */
236	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
237	if (ret < 0)
238		goto err;
 
 
 
239
240	while (1) {
241		leaf = path->nodes[0];
242		slot = path->slots[0];
243
244		/* this is where we start walking through the path */
245		if (slot >= btrfs_header_nritems(leaf)) {
246			/*
247			 * if we've reached the last slot in this leaf we need
248			 * to go to the next leaf and reset everything
249			 */
250			ret = btrfs_next_leaf(root, path);
251			if (ret < 0)
252				goto err;
253			else if (ret > 0)
254				break;
255			continue;
256		}
257
258		btrfs_item_key_to_cpu(leaf, &found_key, slot);
259
260		/* check to make sure this item is what we want */
261		if (found_key.objectid != key.objectid)
262			break;
263		if (btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY)
264			break;
 
 
265
266		di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
267		if (verify_dir_item(root, leaf, di))
268			continue;
 
 
 
 
 
269
270		name_len = btrfs_dir_name_len(leaf, di);
271		total_size += name_len + 1;
 
 
 
 
 
272
273		/* we are just looking for how big our buffer needs to be */
274		if (!size)
275			goto next;
276
277		if (!buffer || (name_len + 1) > size_left) {
278			ret = -ERANGE;
279			goto err;
280		}
281
282		name_ptr = (unsigned long)(di + 1);
283		read_extent_buffer(leaf, buffer, name_ptr, name_len);
284		buffer[name_len] = '\0';
285
286		size_left -= name_len + 1;
287		buffer += name_len + 1;
288next:
289		path->slots[0]++;
 
 
290	}
291	ret = total_size;
292
293err:
 
 
 
 
294	btrfs_free_path(path);
295
296	return ret;
297}
298
299/*
300 * List of handlers for synthetic system.* attributes.  All real ondisk
301 * attributes are handled directly.
302 */
303const struct xattr_handler *btrfs_xattr_handlers[] = {
304#ifdef CONFIG_BTRFS_FS_POSIX_ACL
305	&btrfs_xattr_acl_access_handler,
306	&btrfs_xattr_acl_default_handler,
307#endif
308	NULL,
309};
310
311/*
312 * Check if the attribute is in a supported namespace.
313 *
314 * This applied after the check for the synthetic attributes in the system
315 * namespace.
316 */
317static bool btrfs_is_valid_xattr(const char *name)
318{
319	return !strncmp(name, XATTR_SECURITY_PREFIX,
320			XATTR_SECURITY_PREFIX_LEN) ||
321	       !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN) ||
322	       !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) ||
323	       !strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN);
324}
325
326ssize_t btrfs_getxattr(struct dentry *dentry, const char *name,
327		       void *buffer, size_t size)
 
 
 
328{
329	/*
330	 * If this is a request for a synthetic attribute in the system.*
331	 * namespace use the generic infrastructure to resolve a handler
332	 * for it via sb->s_xattr.
333	 */
334	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
335		return generic_getxattr(dentry, name, buffer, size);
336
337	if (!btrfs_is_valid_xattr(name))
338		return -EOPNOTSUPP;
339	return __btrfs_getxattr(dentry->d_inode, name, buffer, size);
340}
341
342int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value,
343		   size_t size, int flags)
 
 
 
344{
345	struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root;
 
 
 
346
347	/*
348	 * The permission on security.* and system.* is not checked
349	 * in permission().
 
 
350	 */
351	if (btrfs_root_readonly(root))
352		return -EROFS;
 
 
 
353
354	/*
355	 * If this is a request for a synthetic attribute in the system.*
356	 * namespace use the generic infrastructure to resolve a handler
357	 * for it via sb->s_xattr.
358	 */
359	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
360		return generic_setxattr(dentry, name, value, size, flags);
361
362	if (!btrfs_is_valid_xattr(name))
363		return -EOPNOTSUPP;
 
 
 
 
 
 
 
 
364
365	if (size == 0)
366		value = "";  /* empty EA, do not remove */
 
367
368	return __btrfs_setxattr(NULL, dentry->d_inode, name, value, size,
369				flags);
370}
371
372int btrfs_removexattr(struct dentry *dentry, const char *name)
 
 
 
 
373{
374	struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root;
 
 
 
 
 
 
 
 
 
 
375
376	/*
377	 * The permission on security.* and system.* is not checked
378	 * in permission().
379	 */
380	if (btrfs_root_readonly(root))
381		return -EROFS;
382
383	/*
384	 * If this is a request for a synthetic attribute in the system.*
385	 * namespace use the generic infrastructure to resolve a handler
386	 * for it via sb->s_xattr.
387	 */
388	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
389		return generic_removexattr(dentry, name);
 
390
391	if (!btrfs_is_valid_xattr(name))
392		return -EOPNOTSUPP;
393
394	return __btrfs_setxattr(NULL, dentry->d_inode, name, NULL, 0,
395				XATTR_REPLACE);
396}
397
398int btrfs_initxattrs(struct inode *inode, const struct xattr *xattr_array,
399		     void *fs_info)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
400{
 
401	const struct xattr *xattr;
402	struct btrfs_trans_handle *trans = fs_info;
403	char *name;
404	int err = 0;
405
 
 
 
 
 
406	for (xattr = xattr_array; xattr->name != NULL; xattr++) {
407		name = kmalloc(XATTR_SECURITY_PREFIX_LEN +
408			       strlen(xattr->name) + 1, GFP_NOFS);
409		if (!name) {
410			err = -ENOMEM;
411			break;
412		}
413		strcpy(name, XATTR_SECURITY_PREFIX);
414		strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
415		err = __btrfs_setxattr(trans, inode, name,
416				       xattr->value, xattr->value_len, 0);
 
 
 
 
417		kfree(name);
418		if (err < 0)
419			break;
420	}
 
421	return err;
422}
423
424int btrfs_xattr_security_init(struct btrfs_trans_handle *trans,
425			      struct inode *inode, struct inode *dir,
426			      const struct qstr *qstr)
427{
428	return security_inode_init_security(inode, dir, qstr,
429					    &btrfs_initxattrs, trans);
430}