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
btrfs_getxattr(struct inode * inode,const char * name,void * buffer,size_t size)27 int 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
78 out:
79 btrfs_free_path(path);
80 return ret;
81 }
82
btrfs_setxattr(struct btrfs_trans_handle * trans,struct inode * inode,const char * name,const void * value,size_t size,int flags)83 int 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 }
216 out:
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 */
btrfs_setxattr_trans(struct inode * inode,const char * name,const void * value,size_t size,int flags)229 int 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, root, BTRFS_I(inode));
269 if (ret)
270 btrfs_abort_transaction(trans, ret);
271 out:
272 if (start_trans)
273 btrfs_end_transaction(trans);
274 return ret;
275 }
276
btrfs_listxattr(struct dentry * dentry,char * buffer,size_t size)277 ssize_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;
348 next:
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
btrfs_xattr_handler_get(const struct xattr_handler * handler,struct dentry * unused,struct inode * inode,const char * name,void * buffer,size_t size)364 static 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
btrfs_xattr_handler_set(const struct xattr_handler * handler,struct mnt_idmap * idmap,struct dentry * unused,struct inode * inode,const char * name,const void * buffer,size_t size,int flags)372 static 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
btrfs_xattr_handler_set_prop(const struct xattr_handler * handler,struct mnt_idmap * idmap,struct dentry * unused,struct inode * inode,const char * name,const void * value,size_t size,int flags)385 static int btrfs_xattr_handler_set_prop(const struct xattr_handler *handler,
386 struct mnt_idmap *idmap,
387 struct dentry *unused, struct inode *inode,
388 const char *name, const void *value,
389 size_t size, int flags)
390 {
391 int ret;
392 struct btrfs_trans_handle *trans;
393 struct btrfs_root *root = BTRFS_I(inode)->root;
394
395 name = xattr_full_name(handler, name);
396 ret = btrfs_validate_prop(BTRFS_I(inode), name, value, size);
397 if (ret)
398 return ret;
399
400 if (btrfs_ignore_prop(BTRFS_I(inode), name))
401 return 0;
402
403 trans = btrfs_start_transaction(root, 2);
404 if (IS_ERR(trans))
405 return PTR_ERR(trans);
406
407 ret = btrfs_set_prop(trans, inode, name, value, size, flags);
408 if (!ret) {
409 inode_inc_iversion(inode);
410 inode_set_ctime_current(inode);
411 ret = btrfs_update_inode(trans, root, BTRFS_I(inode));
412 if (ret)
413 btrfs_abort_transaction(trans, ret);
414 }
415
416 btrfs_end_transaction(trans);
417
418 return ret;
419 }
420
421 static const struct xattr_handler btrfs_security_xattr_handler = {
422 .prefix = XATTR_SECURITY_PREFIX,
423 .get = btrfs_xattr_handler_get,
424 .set = btrfs_xattr_handler_set,
425 };
426
427 static const struct xattr_handler btrfs_trusted_xattr_handler = {
428 .prefix = XATTR_TRUSTED_PREFIX,
429 .get = btrfs_xattr_handler_get,
430 .set = btrfs_xattr_handler_set,
431 };
432
433 static const struct xattr_handler btrfs_user_xattr_handler = {
434 .prefix = XATTR_USER_PREFIX,
435 .get = btrfs_xattr_handler_get,
436 .set = btrfs_xattr_handler_set,
437 };
438
439 static const struct xattr_handler btrfs_btrfs_xattr_handler = {
440 .prefix = XATTR_BTRFS_PREFIX,
441 .get = btrfs_xattr_handler_get,
442 .set = btrfs_xattr_handler_set_prop,
443 };
444
445 const struct xattr_handler *btrfs_xattr_handlers[] = {
446 &btrfs_security_xattr_handler,
447 &btrfs_trusted_xattr_handler,
448 &btrfs_user_xattr_handler,
449 &btrfs_btrfs_xattr_handler,
450 NULL,
451 };
452
btrfs_initxattrs(struct inode * inode,const struct xattr * xattr_array,void * fs_private)453 static int btrfs_initxattrs(struct inode *inode,
454 const struct xattr *xattr_array, void *fs_private)
455 {
456 struct btrfs_trans_handle *trans = fs_private;
457 const struct xattr *xattr;
458 unsigned int nofs_flag;
459 char *name;
460 int err = 0;
461
462 /*
463 * We're holding a transaction handle, so use a NOFS memory allocation
464 * context to avoid deadlock if reclaim happens.
465 */
466 nofs_flag = memalloc_nofs_save();
467 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
468 name = kmalloc(XATTR_SECURITY_PREFIX_LEN +
469 strlen(xattr->name) + 1, GFP_KERNEL);
470 if (!name) {
471 err = -ENOMEM;
472 break;
473 }
474 strcpy(name, XATTR_SECURITY_PREFIX);
475 strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
476 err = btrfs_setxattr(trans, inode, name, xattr->value,
477 xattr->value_len, 0);
478 kfree(name);
479 if (err < 0)
480 break;
481 }
482 memalloc_nofs_restore(nofs_flag);
483 return err;
484 }
485
btrfs_xattr_security_init(struct btrfs_trans_handle * trans,struct inode * inode,struct inode * dir,const struct qstr * qstr)486 int btrfs_xattr_security_init(struct btrfs_trans_handle *trans,
487 struct inode *inode, struct inode *dir,
488 const struct qstr *qstr)
489 {
490 return security_inode_init_security(inode, dir, qstr,
491 &btrfs_initxattrs, trans);
492 }
493