2 * Copyright (C) 2007 Red Hat. All rights reserved.
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.
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.
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.
19 #include <linux/init.h>
21 #include <linux/slab.h>
22 #include <linux/rwsem.h>
23 #include <linux/xattr.h>
24 #include <linux/security.h>
25 #include <linux/posix_acl_xattr.h>
27 #include "btrfs_inode.h"
28 #include "transaction.h"
35 ssize_t __btrfs_getxattr(struct inode *inode, const char *name,
36 void *buffer, size_t size)
38 struct btrfs_dir_item *di;
39 struct btrfs_root *root = BTRFS_I(inode)->root;
40 struct btrfs_path *path;
41 struct extent_buffer *leaf;
43 unsigned long data_ptr;
45 path = btrfs_alloc_path();
49 /* lookup the xattr by name */
50 di = btrfs_lookup_xattr(NULL, root, path, btrfs_ino(inode), name,
55 } else if (IS_ERR(di)) {
60 leaf = path->nodes[0];
61 /* if size is 0, that means we want the size of the attr */
63 ret = btrfs_dir_data_len(leaf, di);
67 /* now get the data out of our dir_item */
68 if (btrfs_dir_data_len(leaf, di) > size) {
74 * The way things are packed into the leaf is like this
75 * |struct btrfs_dir_item|name|data|
76 * where name is the xattr name, so security.foo, and data is the
77 * content of the xattr. data_ptr points to the location in memory
78 * where the data starts in the in memory leaf
80 data_ptr = (unsigned long)((char *)(di + 1) +
81 btrfs_dir_name_len(leaf, di));
82 read_extent_buffer(leaf, buffer, data_ptr,
83 btrfs_dir_data_len(leaf, di));
84 ret = btrfs_dir_data_len(leaf, di);
87 btrfs_free_path(path);
91 static int do_setxattr(struct btrfs_trans_handle *trans,
92 struct inode *inode, const char *name,
93 const void *value, size_t size, int flags)
95 struct btrfs_dir_item *di = NULL;
96 struct btrfs_root *root = BTRFS_I(inode)->root;
97 struct btrfs_path *path;
98 size_t name_len = strlen(name);
101 if (name_len + size > BTRFS_MAX_XATTR_SIZE(root))
104 path = btrfs_alloc_path();
107 path->skip_release_on_error = 1;
110 di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode),
112 if (!di && (flags & XATTR_REPLACE))
117 ret = btrfs_delete_one_dir_name(trans, root, path, di);
122 * For a replace we can't just do the insert blindly.
123 * Do a lookup first (read-only btrfs_search_slot), and return if xattr
124 * doesn't exist. If it exists, fall down below to the insert/replace
125 * path - we can't race with a concurrent xattr delete, because the VFS
126 * locks the inode's i_mutex before calling setxattr or removexattr.
128 if (flags & XATTR_REPLACE) {
129 ASSERT(mutex_is_locked(&inode->i_mutex));
130 di = btrfs_lookup_xattr(NULL, root, path, btrfs_ino(inode),
138 btrfs_release_path(path);
142 ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(inode),
143 name, name_len, value, size);
144 if (ret == -EOVERFLOW) {
146 * We have an existing item in a leaf, split_leaf couldn't
147 * expand it. That item might have or not a dir_item that
148 * matches our target xattr, so lets check.
151 btrfs_assert_tree_locked(path->nodes[0]);
152 di = btrfs_match_dir_item_name(root, path, name, name_len);
153 if (!di && !(flags & XATTR_REPLACE)) {
157 } else if (ret == -EEXIST) {
159 di = btrfs_match_dir_item_name(root, path, name, name_len);
160 ASSERT(di); /* logic error */
165 if (di && (flags & XATTR_CREATE)) {
172 * We're doing a replace, and it must be atomic, that is, at
173 * any point in time we have either the old or the new xattr
174 * value in the tree. We don't want readers (getxattr and
175 * listxattrs) to miss a value, this is specially important
178 const int slot = path->slots[0];
179 struct extent_buffer *leaf = path->nodes[0];
180 const u16 old_data_len = btrfs_dir_data_len(leaf, di);
181 const u32 item_size = btrfs_item_size_nr(leaf, slot);
182 const u32 data_size = sizeof(*di) + name_len + size;
183 struct btrfs_item *item;
184 unsigned long data_ptr;
187 if (size > old_data_len) {
188 if (btrfs_leaf_free_space(root, leaf) <
189 (size - old_data_len)) {
195 if (old_data_len + name_len + sizeof(*di) == item_size) {
196 /* No other xattrs packed in the same leaf item. */
197 if (size > old_data_len)
198 btrfs_extend_item(root, path,
199 size - old_data_len);
200 else if (size < old_data_len)
201 btrfs_truncate_item(root, path, data_size, 1);
203 /* There are other xattrs packed in the same item. */
204 ret = btrfs_delete_one_dir_name(trans, root, path, di);
207 btrfs_extend_item(root, path, data_size);
210 item = btrfs_item_nr(slot);
211 ptr = btrfs_item_ptr(leaf, slot, char);
212 ptr += btrfs_item_size(leaf, item) - data_size;
213 di = (struct btrfs_dir_item *)ptr;
214 btrfs_set_dir_data_len(leaf, di, size);
215 data_ptr = ((unsigned long)(di + 1)) + name_len;
216 write_extent_buffer(leaf, value, data_ptr, size);
217 btrfs_mark_buffer_dirty(leaf);
220 * Insert, and we had space for the xattr, so path->slots[0] is
221 * where our xattr dir_item is and btrfs_insert_xattr_item()
226 btrfs_free_path(path);
231 * @value: "" makes the attribute to empty, NULL removes it
233 int __btrfs_setxattr(struct btrfs_trans_handle *trans,
234 struct inode *inode, const char *name,
235 const void *value, size_t size, int flags)
237 struct btrfs_root *root = BTRFS_I(inode)->root;
241 return do_setxattr(trans, inode, name, value, size, flags);
243 trans = btrfs_start_transaction(root, 2);
245 return PTR_ERR(trans);
247 ret = do_setxattr(trans, inode, name, value, size, flags);
251 inode_inc_iversion(inode);
252 inode->i_ctime = CURRENT_TIME;
253 set_bit(BTRFS_INODE_COPY_EVERYTHING, &BTRFS_I(inode)->runtime_flags);
254 ret = btrfs_update_inode(trans, root, inode);
257 btrfs_end_transaction(trans, root);
261 ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
263 struct btrfs_key key, found_key;
264 struct inode *inode = d_inode(dentry);
265 struct btrfs_root *root = BTRFS_I(inode)->root;
266 struct btrfs_path *path;
267 struct extent_buffer *leaf;
268 struct btrfs_dir_item *di;
270 size_t total_size = 0, size_left = size;
271 unsigned long name_ptr;
275 * ok we want all objects associated with this id.
276 * NOTE: we set key.offset = 0; because we want to start with the
277 * first xattr that we find and walk forward
279 key.objectid = btrfs_ino(inode);
280 key.type = BTRFS_XATTR_ITEM_KEY;
283 path = btrfs_alloc_path();
288 /* search for our xattrs */
289 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
294 leaf = path->nodes[0];
295 slot = path->slots[0];
297 /* this is where we start walking through the path */
298 if (slot >= btrfs_header_nritems(leaf)) {
300 * if we've reached the last slot in this leaf we need
301 * to go to the next leaf and reset everything
303 ret = btrfs_next_leaf(root, path);
311 btrfs_item_key_to_cpu(leaf, &found_key, slot);
313 /* check to make sure this item is what we want */
314 if (found_key.objectid != key.objectid)
316 if (found_key.type != BTRFS_XATTR_ITEM_KEY)
319 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
320 if (verify_dir_item(root, leaf, di))
323 name_len = btrfs_dir_name_len(leaf, di);
324 total_size += name_len + 1;
326 /* we are just looking for how big our buffer needs to be */
330 if (!buffer || (name_len + 1) > size_left) {
335 name_ptr = (unsigned long)(di + 1);
336 read_extent_buffer(leaf, buffer, name_ptr, name_len);
337 buffer[name_len] = '\0';
339 size_left -= name_len + 1;
340 buffer += name_len + 1;
347 btrfs_free_path(path);
353 * List of handlers for synthetic system.* attributes. All real ondisk
354 * attributes are handled directly.
356 const struct xattr_handler *btrfs_xattr_handlers[] = {
357 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
358 &posix_acl_access_xattr_handler,
359 &posix_acl_default_xattr_handler,
365 * Check if the attribute is in a supported namespace.
367 * This is applied after the check for the synthetic attributes in the system
370 static int btrfs_is_valid_xattr(const char *name)
372 int len = strlen(name);
375 if (!strncmp(name, XATTR_SECURITY_PREFIX,
376 XATTR_SECURITY_PREFIX_LEN))
377 prefixlen = XATTR_SECURITY_PREFIX_LEN;
378 else if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
379 prefixlen = XATTR_SYSTEM_PREFIX_LEN;
380 else if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN))
381 prefixlen = XATTR_TRUSTED_PREFIX_LEN;
382 else if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN))
383 prefixlen = XATTR_USER_PREFIX_LEN;
384 else if (!strncmp(name, XATTR_BTRFS_PREFIX, XATTR_BTRFS_PREFIX_LEN))
385 prefixlen = XATTR_BTRFS_PREFIX_LEN;
390 * The name cannot consist of just prefix
392 if (len <= prefixlen)
398 ssize_t btrfs_getxattr(struct dentry *dentry, const char *name,
399 void *buffer, size_t size)
404 * If this is a request for a synthetic attribute in the system.*
405 * namespace use the generic infrastructure to resolve a handler
406 * for it via sb->s_xattr.
408 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
409 return generic_getxattr(dentry, name, buffer, size);
411 ret = btrfs_is_valid_xattr(name);
414 return __btrfs_getxattr(d_inode(dentry), name, buffer, size);
417 int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value,
418 size_t size, int flags)
420 struct btrfs_root *root = BTRFS_I(d_inode(dentry))->root;
424 * The permission on security.* and system.* is not checked
427 if (btrfs_root_readonly(root))
431 * If this is a request for a synthetic attribute in the system.*
432 * namespace use the generic infrastructure to resolve a handler
433 * for it via sb->s_xattr.
435 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
436 return generic_setxattr(dentry, name, value, size, flags);
438 ret = btrfs_is_valid_xattr(name);
442 if (!strncmp(name, XATTR_BTRFS_PREFIX, XATTR_BTRFS_PREFIX_LEN))
443 return btrfs_set_prop(d_inode(dentry), name,
447 value = ""; /* empty EA, do not remove */
449 return __btrfs_setxattr(NULL, d_inode(dentry), name, value, size,
453 int btrfs_removexattr(struct dentry *dentry, const char *name)
455 struct btrfs_root *root = BTRFS_I(d_inode(dentry))->root;
459 * The permission on security.* and system.* is not checked
462 if (btrfs_root_readonly(root))
466 * If this is a request for a synthetic attribute in the system.*
467 * namespace use the generic infrastructure to resolve a handler
468 * for it via sb->s_xattr.
470 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
471 return generic_removexattr(dentry, name);
473 ret = btrfs_is_valid_xattr(name);
477 if (!strncmp(name, XATTR_BTRFS_PREFIX, XATTR_BTRFS_PREFIX_LEN))
478 return btrfs_set_prop(d_inode(dentry), name,
479 NULL, 0, XATTR_REPLACE);
481 return __btrfs_setxattr(NULL, d_inode(dentry), name, NULL, 0,
485 static int btrfs_initxattrs(struct inode *inode,
486 const struct xattr *xattr_array, void *fs_info)
488 const struct xattr *xattr;
489 struct btrfs_trans_handle *trans = fs_info;
493 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
494 name = kmalloc(XATTR_SECURITY_PREFIX_LEN +
495 strlen(xattr->name) + 1, GFP_NOFS);
500 strcpy(name, XATTR_SECURITY_PREFIX);
501 strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
502 err = __btrfs_setxattr(trans, inode, name,
503 xattr->value, xattr->value_len, 0);
511 int btrfs_xattr_security_init(struct btrfs_trans_handle *trans,
512 struct inode *inode, struct inode *dir,
513 const struct qstr *qstr)
515 return security_inode_init_security(inode, dir, qstr,
516 &btrfs_initxattrs, trans);