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
__btrfs_getxattr(struct inode * inode,const char * name,void * buffer,size_t size)32 ssize_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
83 out:
84 btrfs_free_path(path);
85 return ret;
86 }
87
do_setxattr(struct btrfs_trans_handle * trans,struct inode * inode,const char * name,const void * value,size_t size,int flags)88 static 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
127 again:
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 }
173 out:
174 btrfs_free_path(path);
175 return ret;
176 }
177
178 /*
179 * @value: "" makes the attribute to empty, NULL removes it
180 */
__btrfs_setxattr(struct btrfs_trans_handle * trans,struct inode * inode,const char * name,const void * value,size_t size,int flags)181 int __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->i_ctime = CURRENT_TIME;
200 ret = btrfs_update_inode(trans, root, inode);
201 BUG_ON(ret);
202 out:
203 btrfs_end_transaction(trans, root);
204 return ret;
205 }
206
btrfs_listxattr(struct dentry * dentry,char * buffer,size_t size)207 ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
208 {
209 struct btrfs_key key, found_key;
210 struct inode *inode = dentry->d_inode;
211 struct btrfs_root *root = BTRFS_I(inode)->root;
212 struct btrfs_path *path;
213 struct extent_buffer *leaf;
214 struct btrfs_dir_item *di;
215 int ret = 0, slot;
216 size_t total_size = 0, size_left = size;
217 unsigned long name_ptr;
218 size_t name_len;
219
220 /*
221 * ok we want all objects associated with this id.
222 * NOTE: we set key.offset = 0; because we want to start with the
223 * first xattr that we find and walk forward
224 */
225 key.objectid = btrfs_ino(inode);
226 btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
227 key.offset = 0;
228
229 path = btrfs_alloc_path();
230 if (!path)
231 return -ENOMEM;
232 path->reada = 2;
233
234 /* search for our xattrs */
235 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
236 if (ret < 0)
237 goto err;
238
239 while (1) {
240 leaf = path->nodes[0];
241 slot = path->slots[0];
242
243 /* this is where we start walking through the path */
244 if (slot >= btrfs_header_nritems(leaf)) {
245 /*
246 * if we've reached the last slot in this leaf we need
247 * to go to the next leaf and reset everything
248 */
249 ret = btrfs_next_leaf(root, path);
250 if (ret < 0)
251 goto err;
252 else if (ret > 0)
253 break;
254 continue;
255 }
256
257 btrfs_item_key_to_cpu(leaf, &found_key, slot);
258
259 /* check to make sure this item is what we want */
260 if (found_key.objectid != key.objectid)
261 break;
262 if (btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY)
263 break;
264
265 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
266 if (verify_dir_item(root, leaf, di))
267 continue;
268
269 name_len = btrfs_dir_name_len(leaf, di);
270 total_size += name_len + 1;
271
272 /* we are just looking for how big our buffer needs to be */
273 if (!size)
274 goto next;
275
276 if (!buffer || (name_len + 1) > size_left) {
277 ret = -ERANGE;
278 goto err;
279 }
280
281 name_ptr = (unsigned long)(di + 1);
282 read_extent_buffer(leaf, buffer, name_ptr, name_len);
283 buffer[name_len] = '\0';
284
285 size_left -= name_len + 1;
286 buffer += name_len + 1;
287 next:
288 path->slots[0]++;
289 }
290 ret = total_size;
291
292 err:
293 btrfs_free_path(path);
294
295 return ret;
296 }
297
298 /*
299 * List of handlers for synthetic system.* attributes. All real ondisk
300 * attributes are handled directly.
301 */
302 const struct xattr_handler *btrfs_xattr_handlers[] = {
303 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
304 &btrfs_xattr_acl_access_handler,
305 &btrfs_xattr_acl_default_handler,
306 #endif
307 NULL,
308 };
309
310 /*
311 * Check if the attribute is in a supported namespace.
312 *
313 * This applied after the check for the synthetic attributes in the system
314 * namespace.
315 */
btrfs_is_valid_xattr(const char * name)316 static bool btrfs_is_valid_xattr(const char *name)
317 {
318 return !strncmp(name, XATTR_SECURITY_PREFIX,
319 XATTR_SECURITY_PREFIX_LEN) ||
320 !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN) ||
321 !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) ||
322 !strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN);
323 }
324
btrfs_getxattr(struct dentry * dentry,const char * name,void * buffer,size_t size)325 ssize_t btrfs_getxattr(struct dentry *dentry, const char *name,
326 void *buffer, size_t size)
327 {
328 /*
329 * If this is a request for a synthetic attribute in the system.*
330 * namespace use the generic infrastructure to resolve a handler
331 * for it via sb->s_xattr.
332 */
333 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
334 return generic_getxattr(dentry, name, buffer, size);
335
336 if (!btrfs_is_valid_xattr(name))
337 return -EOPNOTSUPP;
338 return __btrfs_getxattr(dentry->d_inode, name, buffer, size);
339 }
340
btrfs_setxattr(struct dentry * dentry,const char * name,const void * value,size_t size,int flags)341 int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value,
342 size_t size, int flags)
343 {
344 struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root;
345
346 /*
347 * The permission on security.* and system.* is not checked
348 * in permission().
349 */
350 if (btrfs_root_readonly(root))
351 return -EROFS;
352
353 /*
354 * If this is a request for a synthetic attribute in the system.*
355 * namespace use the generic infrastructure to resolve a handler
356 * for it via sb->s_xattr.
357 */
358 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
359 return generic_setxattr(dentry, name, value, size, flags);
360
361 if (!btrfs_is_valid_xattr(name))
362 return -EOPNOTSUPP;
363
364 if (size == 0)
365 value = ""; /* empty EA, do not remove */
366
367 return __btrfs_setxattr(NULL, dentry->d_inode, name, value, size,
368 flags);
369 }
370
btrfs_removexattr(struct dentry * dentry,const char * name)371 int btrfs_removexattr(struct dentry *dentry, const char *name)
372 {
373 struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root;
374
375 /*
376 * The permission on security.* and system.* is not checked
377 * in permission().
378 */
379 if (btrfs_root_readonly(root))
380 return -EROFS;
381
382 /*
383 * If this is a request for a synthetic attribute in the system.*
384 * namespace use the generic infrastructure to resolve a handler
385 * for it via sb->s_xattr.
386 */
387 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
388 return generic_removexattr(dentry, name);
389
390 if (!btrfs_is_valid_xattr(name))
391 return -EOPNOTSUPP;
392
393 return __btrfs_setxattr(NULL, dentry->d_inode, name, NULL, 0,
394 XATTR_REPLACE);
395 }
396
btrfs_initxattrs(struct inode * inode,const struct xattr * xattr_array,void * fs_info)397 int btrfs_initxattrs(struct inode *inode, const struct xattr *xattr_array,
398 void *fs_info)
399 {
400 const struct xattr *xattr;
401 struct btrfs_trans_handle *trans = fs_info;
402 char *name;
403 int err = 0;
404
405 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
406 name = kmalloc(XATTR_SECURITY_PREFIX_LEN +
407 strlen(xattr->name) + 1, GFP_NOFS);
408 if (!name) {
409 err = -ENOMEM;
410 break;
411 }
412 strcpy(name, XATTR_SECURITY_PREFIX);
413 strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
414 err = __btrfs_setxattr(trans, inode, name,
415 xattr->value, xattr->value_len, 0);
416 kfree(name);
417 if (err < 0)
418 break;
419 }
420 return err;
421 }
422
btrfs_xattr_security_init(struct btrfs_trans_handle * trans,struct inode * inode,struct inode * dir,const struct qstr * qstr)423 int btrfs_xattr_security_init(struct btrfs_trans_handle *trans,
424 struct inode *inode, struct inode *dir,
425 const struct qstr *qstr)
426 {
427 return security_inode_init_security(inode, dir, qstr,
428 &btrfs_initxattrs, trans);
429 }
430