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, inode->i_ino, 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 /* first lets see if we already have this xattr */
106 di = btrfs_lookup_xattr(trans, root, path, inode->i_ino, name,
107 strlen(name), -1);
108 if (IS_ERR(di)) {
109 ret = PTR_ERR(di);
110 goto out;
111 }
112
113 /* ok we already have this xattr, lets remove it */
114 if (di) {
115 /* if we want create only exit */
116 if (flags & XATTR_CREATE) {
117 ret = -EEXIST;
118 goto out;
119 }
120
121 ret = btrfs_delete_one_dir_name(trans, root, path, di);
122 BUG_ON(ret);
123 btrfs_release_path(root, path);
124
125 /* if we don't have a value then we are removing the xattr */
126 if (!value)
127 goto out;
128 } else {
129 btrfs_release_path(root, path);
130
131 if (flags & XATTR_REPLACE) {
132 /* we couldn't find the attr to replace */
133 ret = -ENODATA;
134 goto out;
135 }
136 }
137
138 /* ok we have to create a completely new xattr */
139 ret = btrfs_insert_xattr_item(trans, root, path, inode->i_ino,
140 name, name_len, value, size);
141 BUG_ON(ret);
142 out:
143 btrfs_free_path(path);
144 return ret;
145 }
146
__btrfs_setxattr(struct btrfs_trans_handle * trans,struct inode * inode,const char * name,const void * value,size_t size,int flags)147 int __btrfs_setxattr(struct btrfs_trans_handle *trans,
148 struct inode *inode, const char *name,
149 const void *value, size_t size, int flags)
150 {
151 struct btrfs_root *root = BTRFS_I(inode)->root;
152 int ret;
153
154 if (trans)
155 return do_setxattr(trans, inode, name, value, size, flags);
156
157 trans = btrfs_start_transaction(root, 2);
158 if (IS_ERR(trans))
159 return PTR_ERR(trans);
160
161 btrfs_set_trans_block_group(trans, inode);
162
163 ret = do_setxattr(trans, inode, name, value, size, flags);
164 if (ret)
165 goto out;
166
167 inode->i_ctime = CURRENT_TIME;
168 ret = btrfs_update_inode(trans, root, inode);
169 BUG_ON(ret);
170 out:
171 btrfs_end_transaction_throttle(trans, root);
172 return ret;
173 }
174
btrfs_listxattr(struct dentry * dentry,char * buffer,size_t size)175 ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
176 {
177 struct btrfs_key key, found_key;
178 struct inode *inode = dentry->d_inode;
179 struct btrfs_root *root = BTRFS_I(inode)->root;
180 struct btrfs_path *path;
181 struct extent_buffer *leaf;
182 struct btrfs_dir_item *di;
183 int ret = 0, slot;
184 size_t total_size = 0, size_left = size;
185 unsigned long name_ptr;
186 size_t name_len;
187
188 /*
189 * ok we want all objects associated with this id.
190 * NOTE: we set key.offset = 0; because we want to start with the
191 * first xattr that we find and walk forward
192 */
193 key.objectid = inode->i_ino;
194 btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
195 key.offset = 0;
196
197 path = btrfs_alloc_path();
198 if (!path)
199 return -ENOMEM;
200 path->reada = 2;
201
202 /* search for our xattrs */
203 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
204 if (ret < 0)
205 goto err;
206
207 while (1) {
208 leaf = path->nodes[0];
209 slot = path->slots[0];
210
211 /* this is where we start walking through the path */
212 if (slot >= btrfs_header_nritems(leaf)) {
213 /*
214 * if we've reached the last slot in this leaf we need
215 * to go to the next leaf and reset everything
216 */
217 ret = btrfs_next_leaf(root, path);
218 if (ret < 0)
219 goto err;
220 else if (ret > 0)
221 break;
222 continue;
223 }
224
225 btrfs_item_key_to_cpu(leaf, &found_key, slot);
226
227 /* check to make sure this item is what we want */
228 if (found_key.objectid != key.objectid)
229 break;
230 if (btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY)
231 break;
232
233 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
234 if (verify_dir_item(root, leaf, di))
235 continue;
236
237 name_len = btrfs_dir_name_len(leaf, di);
238 total_size += name_len + 1;
239
240 /* we are just looking for how big our buffer needs to be */
241 if (!size)
242 goto next;
243
244 if (!buffer || (name_len + 1) > size_left) {
245 ret = -ERANGE;
246 goto err;
247 }
248
249 name_ptr = (unsigned long)(di + 1);
250 read_extent_buffer(leaf, buffer, name_ptr, name_len);
251 buffer[name_len] = '\0';
252
253 size_left -= name_len + 1;
254 buffer += name_len + 1;
255 next:
256 path->slots[0]++;
257 }
258 ret = total_size;
259
260 err:
261 btrfs_free_path(path);
262
263 return ret;
264 }
265
266 /*
267 * List of handlers for synthetic system.* attributes. All real ondisk
268 * attributes are handled directly.
269 */
270 const struct xattr_handler *btrfs_xattr_handlers[] = {
271 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
272 &btrfs_xattr_acl_access_handler,
273 &btrfs_xattr_acl_default_handler,
274 #endif
275 NULL,
276 };
277
278 /*
279 * Check if the attribute is in a supported namespace.
280 *
281 * This applied after the check for the synthetic attributes in the system
282 * namespace.
283 */
btrfs_is_valid_xattr(const char * name)284 static bool btrfs_is_valid_xattr(const char *name)
285 {
286 return !strncmp(name, XATTR_SECURITY_PREFIX,
287 XATTR_SECURITY_PREFIX_LEN) ||
288 !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN) ||
289 !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) ||
290 !strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN);
291 }
292
btrfs_getxattr(struct dentry * dentry,const char * name,void * buffer,size_t size)293 ssize_t btrfs_getxattr(struct dentry *dentry, const char *name,
294 void *buffer, size_t size)
295 {
296 /*
297 * If this is a request for a synthetic attribute in the system.*
298 * namespace use the generic infrastructure to resolve a handler
299 * for it via sb->s_xattr.
300 */
301 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
302 return generic_getxattr(dentry, name, buffer, size);
303
304 if (!btrfs_is_valid_xattr(name))
305 return -EOPNOTSUPP;
306 return __btrfs_getxattr(dentry->d_inode, name, buffer, size);
307 }
308
btrfs_setxattr(struct dentry * dentry,const char * name,const void * value,size_t size,int flags)309 int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value,
310 size_t size, int flags)
311 {
312 struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root;
313
314 /*
315 * The permission on security.* and system.* is not checked
316 * in permission().
317 */
318 if (btrfs_root_readonly(root))
319 return -EROFS;
320
321 /*
322 * If this is a request for a synthetic attribute in the system.*
323 * namespace use the generic infrastructure to resolve a handler
324 * for it via sb->s_xattr.
325 */
326 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
327 return generic_setxattr(dentry, name, value, size, flags);
328
329 if (!btrfs_is_valid_xattr(name))
330 return -EOPNOTSUPP;
331
332 if (size == 0)
333 value = ""; /* empty EA, do not remove */
334
335 return __btrfs_setxattr(NULL, dentry->d_inode, name, value, size,
336 flags);
337 }
338
btrfs_removexattr(struct dentry * dentry,const char * name)339 int btrfs_removexattr(struct dentry *dentry, const char *name)
340 {
341 struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root;
342
343 /*
344 * The permission on security.* and system.* is not checked
345 * in permission().
346 */
347 if (btrfs_root_readonly(root))
348 return -EROFS;
349
350 /*
351 * If this is a request for a synthetic attribute in the system.*
352 * namespace use the generic infrastructure to resolve a handler
353 * for it via sb->s_xattr.
354 */
355 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
356 return generic_removexattr(dentry, name);
357
358 if (!btrfs_is_valid_xattr(name))
359 return -EOPNOTSUPP;
360
361 return __btrfs_setxattr(NULL, dentry->d_inode, name, NULL, 0,
362 XATTR_REPLACE);
363 }
364
btrfs_xattr_security_init(struct btrfs_trans_handle * trans,struct inode * inode,struct inode * dir,const struct qstr * qstr)365 int btrfs_xattr_security_init(struct btrfs_trans_handle *trans,
366 struct inode *inode, struct inode *dir,
367 const struct qstr *qstr)
368 {
369 int err;
370 size_t len;
371 void *value;
372 char *suffix;
373 char *name;
374
375 err = security_inode_init_security(inode, dir, qstr, &suffix, &value,
376 &len);
377 if (err) {
378 if (err == -EOPNOTSUPP)
379 return 0;
380 return err;
381 }
382
383 name = kmalloc(XATTR_SECURITY_PREFIX_LEN + strlen(suffix) + 1,
384 GFP_NOFS);
385 if (!name) {
386 err = -ENOMEM;
387 } else {
388 strcpy(name, XATTR_SECURITY_PREFIX);
389 strcpy(name + XATTR_SECURITY_PREFIX_LEN, suffix);
390 err = __btrfs_setxattr(trans, inode, name, value, len, 0);
391 kfree(name);
392 }
393
394 kfree(suffix);
395 kfree(value);
396 return err;
397 }
398