xref: /openbmc/linux/fs/ubifs/xattr.c (revision d07d3a7e)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * This file is part of UBIFS.
4  *
5  * Copyright (C) 2006-2008 Nokia Corporation.
6  *
7  * Authors: Artem Bityutskiy (Битюцкий Артём)
8  *          Adrian Hunter
9  */
10 
11 /*
12  * This file implements UBIFS extended attributes support.
13  *
14  * Extended attributes are implemented as regular inodes with attached data,
15  * which limits extended attribute size to UBIFS block size (4KiB). Names of
16  * extended attributes are described by extended attribute entries (xentries),
17  * which are almost identical to directory entries, but have different key type.
18  *
19  * In other words, the situation with extended attributes is very similar to
20  * directories. Indeed, any inode (but of course not xattr inodes) may have a
21  * number of associated xentries, just like directory inodes have associated
22  * directory entries. Extended attribute entries store the name of the extended
23  * attribute, the host inode number, and the extended attribute inode number.
24  * Similarly, direntries store the name, the parent and the target inode
25  * numbers. Thus, most of the common UBIFS mechanisms may be re-used for
26  * extended attributes.
27  *
28  * The number of extended attributes is not limited, but there is Linux
29  * limitation on the maximum possible size of the list of all extended
30  * attributes associated with an inode (%XATTR_LIST_MAX), so UBIFS makes sure
31  * the sum of all extended attribute names of the inode does not exceed that
32  * limit.
33  *
34  * Extended attributes are synchronous, which means they are written to the
35  * flash media synchronously and there is no write-back for extended attribute
36  * inodes. The extended attribute values are not stored in compressed form on
37  * the media.
38  *
39  * Since extended attributes are represented by regular inodes, they are cached
40  * in the VFS inode cache. The xentries are cached in the LNC cache (see
41  * tnc.c).
42  *
43  * ACL support is not implemented.
44  */
45 
46 #include "ubifs.h"
47 #include <linux/fs.h>
48 #include <linux/slab.h>
49 #include <linux/xattr.h>
50 
51 /*
52  * Extended attribute type constants.
53  *
54  * USER_XATTR: user extended attribute ("user.*")
55  * TRUSTED_XATTR: trusted extended attribute ("trusted.*)
56  * SECURITY_XATTR: security extended attribute ("security.*")
57  */
58 enum {
59 	USER_XATTR,
60 	TRUSTED_XATTR,
61 	SECURITY_XATTR,
62 };
63 
64 static const struct inode_operations empty_iops;
65 static const struct file_operations empty_fops;
66 
67 /**
68  * create_xattr - create an extended attribute.
69  * @c: UBIFS file-system description object
70  * @host: host inode
71  * @nm: extended attribute name
72  * @value: extended attribute value
73  * @size: size of extended attribute value
74  *
75  * This is a helper function which creates an extended attribute of name @nm
76  * and value @value for inode @host. The host inode is also updated on flash
77  * because the ctime and extended attribute accounting data changes. This
78  * function returns zero in case of success and a negative error code in case
79  * of failure.
80  */
create_xattr(struct ubifs_info * c,struct inode * host,const struct fscrypt_name * nm,const void * value,int size)81 static int create_xattr(struct ubifs_info *c, struct inode *host,
82 			const struct fscrypt_name *nm, const void *value, int size)
83 {
84 	int err, names_len;
85 	struct inode *inode;
86 	struct ubifs_inode *ui, *host_ui = ubifs_inode(host);
87 	struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
88 				.new_ino_d = ALIGN(size, 8), .dirtied_ino = 1,
89 				.dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
90 
91 	if (host_ui->xattr_cnt >= ubifs_xattr_max_cnt(c)) {
92 		ubifs_err(c, "inode %lu already has too many xattrs (%d), cannot create more",
93 			  host->i_ino, host_ui->xattr_cnt);
94 		return -ENOSPC;
95 	}
96 	/*
97 	 * Linux limits the maximum size of the extended attribute names list
98 	 * to %XATTR_LIST_MAX. This means we should not allow creating more
99 	 * extended attributes if the name list becomes larger. This limitation
100 	 * is artificial for UBIFS, though.
101 	 */
102 	names_len = host_ui->xattr_names + host_ui->xattr_cnt + fname_len(nm) + 1;
103 	if (names_len > XATTR_LIST_MAX) {
104 		ubifs_err(c, "cannot add one more xattr name to inode %lu, total names length would become %d, max. is %d",
105 			  host->i_ino, names_len, XATTR_LIST_MAX);
106 		return -ENOSPC;
107 	}
108 
109 	err = ubifs_budget_space(c, &req);
110 	if (err)
111 		return err;
112 
113 	inode = ubifs_new_inode(c, host, S_IFREG | S_IRWXUGO, true);
114 	if (IS_ERR(inode)) {
115 		err = PTR_ERR(inode);
116 		goto out_budg;
117 	}
118 
119 	/* Re-define all operations to be "nothing" */
120 	inode->i_mapping->a_ops = &empty_aops;
121 	inode->i_op = &empty_iops;
122 	inode->i_fop = &empty_fops;
123 
124 	inode->i_flags |= S_SYNC | S_NOATIME | S_NOCMTIME;
125 	ui = ubifs_inode(inode);
126 	ui->xattr = 1;
127 	ui->flags |= UBIFS_XATTR_FL;
128 	ui->data = kmemdup(value, size, GFP_NOFS);
129 	if (!ui->data) {
130 		err = -ENOMEM;
131 		goto out_free;
132 	}
133 	inode->i_size = ui->ui_size = size;
134 	ui->data_len = size;
135 
136 	mutex_lock(&host_ui->ui_mutex);
137 	inode_set_ctime_current(host);
138 	host_ui->xattr_cnt += 1;
139 	host_ui->xattr_size += CALC_DENT_SIZE(fname_len(nm));
140 	host_ui->xattr_size += CALC_XATTR_BYTES(size);
141 	host_ui->xattr_names += fname_len(nm);
142 
143 	/*
144 	 * We handle UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT here because we
145 	 * have to set the UBIFS_CRYPT_FL flag on the host inode.
146 	 * To avoid multiple updates of the same inode in the same operation,
147 	 * let's do it here.
148 	 */
149 	if (strcmp(fname_name(nm), UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT) == 0)
150 		host_ui->flags |= UBIFS_CRYPT_FL;
151 
152 	err = ubifs_jnl_update(c, host, nm, inode, 0, 1);
153 	if (err)
154 		goto out_cancel;
155 	ubifs_set_inode_flags(host);
156 	mutex_unlock(&host_ui->ui_mutex);
157 
158 	ubifs_release_budget(c, &req);
159 	insert_inode_hash(inode);
160 	iput(inode);
161 	return 0;
162 
163 out_cancel:
164 	host_ui->xattr_cnt -= 1;
165 	host_ui->xattr_size -= CALC_DENT_SIZE(fname_len(nm));
166 	host_ui->xattr_size -= CALC_XATTR_BYTES(size);
167 	host_ui->xattr_names -= fname_len(nm);
168 	host_ui->flags &= ~UBIFS_CRYPT_FL;
169 	mutex_unlock(&host_ui->ui_mutex);
170 out_free:
171 	make_bad_inode(inode);
172 	iput(inode);
173 out_budg:
174 	ubifs_release_budget(c, &req);
175 	return err;
176 }
177 
178 /**
179  * change_xattr - change an extended attribute.
180  * @c: UBIFS file-system description object
181  * @host: host inode
182  * @inode: extended attribute inode
183  * @value: extended attribute value
184  * @size: size of extended attribute value
185  *
186  * This helper function changes the value of extended attribute @inode with new
187  * data from @value. Returns zero in case of success and a negative error code
188  * in case of failure.
189  */
change_xattr(struct ubifs_info * c,struct inode * host,struct inode * inode,const void * value,int size)190 static int change_xattr(struct ubifs_info *c, struct inode *host,
191 			struct inode *inode, const void *value, int size)
192 {
193 	int err;
194 	struct ubifs_inode *host_ui = ubifs_inode(host);
195 	struct ubifs_inode *ui = ubifs_inode(inode);
196 	void *buf = NULL;
197 	int old_size;
198 	struct ubifs_budget_req req = { .dirtied_ino = 2,
199 		.dirtied_ino_d = ALIGN(size, 8) + ALIGN(host_ui->data_len, 8) };
200 
201 	ubifs_assert(c, ui->data_len == inode->i_size);
202 	err = ubifs_budget_space(c, &req);
203 	if (err)
204 		return err;
205 
206 	buf = kmemdup(value, size, GFP_NOFS);
207 	if (!buf) {
208 		err = -ENOMEM;
209 		goto out_free;
210 	}
211 	kfree(ui->data);
212 	ui->data = buf;
213 	inode->i_size = ui->ui_size = size;
214 	old_size = ui->data_len;
215 	ui->data_len = size;
216 
217 	mutex_lock(&host_ui->ui_mutex);
218 	inode_set_ctime_current(host);
219 	host_ui->xattr_size -= CALC_XATTR_BYTES(old_size);
220 	host_ui->xattr_size += CALC_XATTR_BYTES(size);
221 
222 	/*
223 	 * It is important to write the host inode after the xattr inode
224 	 * because if the host inode gets synchronized (via 'fsync()'), then
225 	 * the extended attribute inode gets synchronized, because it goes
226 	 * before the host inode in the write-buffer.
227 	 */
228 	err = ubifs_jnl_change_xattr(c, inode, host);
229 	if (err)
230 		goto out_cancel;
231 	mutex_unlock(&host_ui->ui_mutex);
232 
233 	ubifs_release_budget(c, &req);
234 	return 0;
235 
236 out_cancel:
237 	host_ui->xattr_size -= CALC_XATTR_BYTES(size);
238 	host_ui->xattr_size += CALC_XATTR_BYTES(old_size);
239 	mutex_unlock(&host_ui->ui_mutex);
240 	make_bad_inode(inode);
241 out_free:
242 	ubifs_release_budget(c, &req);
243 	return err;
244 }
245 
iget_xattr(struct ubifs_info * c,ino_t inum)246 static struct inode *iget_xattr(struct ubifs_info *c, ino_t inum)
247 {
248 	struct inode *inode;
249 
250 	inode = ubifs_iget(c->vfs_sb, inum);
251 	if (IS_ERR(inode)) {
252 		ubifs_err(c, "dead extended attribute entry, error %d",
253 			  (int)PTR_ERR(inode));
254 		return inode;
255 	}
256 	if (ubifs_inode(inode)->xattr)
257 		return inode;
258 	ubifs_err(c, "corrupt extended attribute entry");
259 	iput(inode);
260 	return ERR_PTR(-EINVAL);
261 }
262 
ubifs_xattr_set(struct inode * host,const char * name,const void * value,size_t size,int flags,bool check_lock)263 int ubifs_xattr_set(struct inode *host, const char *name, const void *value,
264 		    size_t size, int flags, bool check_lock)
265 {
266 	struct inode *inode;
267 	struct ubifs_info *c = host->i_sb->s_fs_info;
268 	struct fscrypt_name nm = { .disk_name = FSTR_INIT((char *)name, strlen(name))};
269 	struct ubifs_dent_node *xent;
270 	union ubifs_key key;
271 	int err;
272 
273 	if (check_lock)
274 		ubifs_assert(c, inode_is_locked(host));
275 
276 	if (size > UBIFS_MAX_INO_DATA)
277 		return -ERANGE;
278 
279 	if (fname_len(&nm) > UBIFS_MAX_NLEN)
280 		return -ENAMETOOLONG;
281 
282 	xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
283 	if (!xent)
284 		return -ENOMEM;
285 
286 	down_write(&ubifs_inode(host)->xattr_sem);
287 	/*
288 	 * The extended attribute entries are stored in LNC, so multiple
289 	 * look-ups do not involve reading the flash.
290 	 */
291 	xent_key_init(c, &key, host->i_ino, &nm);
292 	err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
293 	if (err) {
294 		if (err != -ENOENT)
295 			goto out_free;
296 
297 		if (flags & XATTR_REPLACE)
298 			/* We are asked not to create the xattr */
299 			err = -ENODATA;
300 		else
301 			err = create_xattr(c, host, &nm, value, size);
302 		goto out_free;
303 	}
304 
305 	if (flags & XATTR_CREATE) {
306 		/* We are asked not to replace the xattr */
307 		err = -EEXIST;
308 		goto out_free;
309 	}
310 
311 	inode = iget_xattr(c, le64_to_cpu(xent->inum));
312 	if (IS_ERR(inode)) {
313 		err = PTR_ERR(inode);
314 		goto out_free;
315 	}
316 
317 	err = change_xattr(c, host, inode, value, size);
318 	iput(inode);
319 
320 out_free:
321 	up_write(&ubifs_inode(host)->xattr_sem);
322 	kfree(xent);
323 	return err;
324 }
325 
ubifs_xattr_get(struct inode * host,const char * name,void * buf,size_t size)326 ssize_t ubifs_xattr_get(struct inode *host, const char *name, void *buf,
327 			size_t size)
328 {
329 	struct inode *inode;
330 	struct ubifs_info *c = host->i_sb->s_fs_info;
331 	struct fscrypt_name nm = { .disk_name = FSTR_INIT((char *)name, strlen(name))};
332 	struct ubifs_inode *ui;
333 	struct ubifs_dent_node *xent;
334 	union ubifs_key key;
335 	int err;
336 
337 	if (fname_len(&nm) > UBIFS_MAX_NLEN)
338 		return -ENAMETOOLONG;
339 
340 	xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
341 	if (!xent)
342 		return -ENOMEM;
343 
344 	down_read(&ubifs_inode(host)->xattr_sem);
345 	xent_key_init(c, &key, host->i_ino, &nm);
346 	err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
347 	if (err) {
348 		if (err == -ENOENT)
349 			err = -ENODATA;
350 		goto out_cleanup;
351 	}
352 
353 	inode = iget_xattr(c, le64_to_cpu(xent->inum));
354 	if (IS_ERR(inode)) {
355 		err = PTR_ERR(inode);
356 		goto out_cleanup;
357 	}
358 
359 	ui = ubifs_inode(inode);
360 	ubifs_assert(c, inode->i_size == ui->data_len);
361 	ubifs_assert(c, ubifs_inode(host)->xattr_size > ui->data_len);
362 
363 	if (buf) {
364 		/* If @buf is %NULL we are supposed to return the length */
365 		if (ui->data_len > size) {
366 			err = -ERANGE;
367 			goto out_iput;
368 		}
369 
370 		memcpy(buf, ui->data, ui->data_len);
371 	}
372 	err = ui->data_len;
373 
374 out_iput:
375 	iput(inode);
376 out_cleanup:
377 	up_read(&ubifs_inode(host)->xattr_sem);
378 	kfree(xent);
379 	return err;
380 }
381 
xattr_visible(const char * name)382 static bool xattr_visible(const char *name)
383 {
384 	/* File encryption related xattrs are for internal use only */
385 	if (strcmp(name, UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT) == 0)
386 		return false;
387 
388 	/* Show trusted namespace only for "power" users */
389 	if (strncmp(name, XATTR_TRUSTED_PREFIX,
390 		    XATTR_TRUSTED_PREFIX_LEN) == 0 && !capable(CAP_SYS_ADMIN))
391 		return false;
392 
393 	return true;
394 }
395 
ubifs_listxattr(struct dentry * dentry,char * buffer,size_t size)396 ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size)
397 {
398 	union ubifs_key key;
399 	struct inode *host = d_inode(dentry);
400 	struct ubifs_info *c = host->i_sb->s_fs_info;
401 	struct ubifs_inode *host_ui = ubifs_inode(host);
402 	struct ubifs_dent_node *xent, *pxent = NULL;
403 	int err, len, written = 0;
404 	struct fscrypt_name nm = {0};
405 
406 	dbg_gen("ino %lu ('%pd'), buffer size %zd", host->i_ino,
407 		dentry, size);
408 
409 	down_read(&host_ui->xattr_sem);
410 	len = host_ui->xattr_names + host_ui->xattr_cnt;
411 	if (!buffer) {
412 		/*
413 		 * We should return the minimum buffer size which will fit a
414 		 * null-terminated list of all the extended attribute names.
415 		 */
416 		err = len;
417 		goto out_err;
418 	}
419 
420 	if (len > size) {
421 		err = -ERANGE;
422 		goto out_err;
423 	}
424 
425 	lowest_xent_key(c, &key, host->i_ino);
426 	while (1) {
427 		xent = ubifs_tnc_next_ent(c, &key, &nm);
428 		if (IS_ERR(xent)) {
429 			err = PTR_ERR(xent);
430 			break;
431 		}
432 
433 		fname_name(&nm) = xent->name;
434 		fname_len(&nm) = le16_to_cpu(xent->nlen);
435 
436 		if (xattr_visible(xent->name)) {
437 			memcpy(buffer + written, fname_name(&nm), fname_len(&nm) + 1);
438 			written += fname_len(&nm) + 1;
439 		}
440 
441 		kfree(pxent);
442 		pxent = xent;
443 		key_read(c, &xent->key, &key);
444 	}
445 	kfree(pxent);
446 	up_read(&host_ui->xattr_sem);
447 
448 	if (err != -ENOENT) {
449 		ubifs_err(c, "cannot find next direntry, error %d", err);
450 		return err;
451 	}
452 
453 	ubifs_assert(c, written <= size);
454 	return written;
455 
456 out_err:
457 	up_read(&host_ui->xattr_sem);
458 	return err;
459 }
460 
remove_xattr(struct ubifs_info * c,struct inode * host,struct inode * inode,const struct fscrypt_name * nm)461 static int remove_xattr(struct ubifs_info *c, struct inode *host,
462 			struct inode *inode, const struct fscrypt_name *nm)
463 {
464 	int err;
465 	struct ubifs_inode *host_ui = ubifs_inode(host);
466 	struct ubifs_inode *ui = ubifs_inode(inode);
467 	struct ubifs_budget_req req = { .dirtied_ino = 2, .mod_dent = 1,
468 				.dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
469 
470 	ubifs_assert(c, ui->data_len == inode->i_size);
471 
472 	err = ubifs_budget_space(c, &req);
473 	if (err)
474 		return err;
475 
476 	mutex_lock(&host_ui->ui_mutex);
477 	inode_set_ctime_current(host);
478 	host_ui->xattr_cnt -= 1;
479 	host_ui->xattr_size -= CALC_DENT_SIZE(fname_len(nm));
480 	host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
481 	host_ui->xattr_names -= fname_len(nm);
482 
483 	err = ubifs_jnl_delete_xattr(c, host, inode, nm);
484 	if (err)
485 		goto out_cancel;
486 	mutex_unlock(&host_ui->ui_mutex);
487 
488 	ubifs_release_budget(c, &req);
489 	return 0;
490 
491 out_cancel:
492 	host_ui->xattr_cnt += 1;
493 	host_ui->xattr_size += CALC_DENT_SIZE(fname_len(nm));
494 	host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
495 	host_ui->xattr_names += fname_len(nm);
496 	mutex_unlock(&host_ui->ui_mutex);
497 	ubifs_release_budget(c, &req);
498 	make_bad_inode(inode);
499 	return err;
500 }
501 
ubifs_purge_xattrs(struct inode * host)502 int ubifs_purge_xattrs(struct inode *host)
503 {
504 	union ubifs_key key;
505 	struct ubifs_info *c = host->i_sb->s_fs_info;
506 	struct ubifs_dent_node *xent, *pxent = NULL;
507 	struct inode *xino;
508 	struct fscrypt_name nm = {0};
509 	int err;
510 
511 	if (ubifs_inode(host)->xattr_cnt <= ubifs_xattr_max_cnt(c))
512 		return 0;
513 
514 	ubifs_warn(c, "inode %lu has too many xattrs, doing a non-atomic deletion",
515 		   host->i_ino);
516 
517 	down_write(&ubifs_inode(host)->xattr_sem);
518 	lowest_xent_key(c, &key, host->i_ino);
519 	while (1) {
520 		xent = ubifs_tnc_next_ent(c, &key, &nm);
521 		if (IS_ERR(xent)) {
522 			err = PTR_ERR(xent);
523 			break;
524 		}
525 
526 		fname_name(&nm) = xent->name;
527 		fname_len(&nm) = le16_to_cpu(xent->nlen);
528 
529 		xino = ubifs_iget(c->vfs_sb, le64_to_cpu(xent->inum));
530 		if (IS_ERR(xino)) {
531 			err = PTR_ERR(xino);
532 			ubifs_err(c, "dead directory entry '%s', error %d",
533 				  xent->name, err);
534 			ubifs_ro_mode(c, err);
535 			kfree(pxent);
536 			kfree(xent);
537 			goto out_err;
538 		}
539 
540 		ubifs_assert(c, ubifs_inode(xino)->xattr);
541 
542 		clear_nlink(xino);
543 		err = remove_xattr(c, host, xino, &nm);
544 		if (err) {
545 			kfree(pxent);
546 			kfree(xent);
547 			iput(xino);
548 			ubifs_err(c, "cannot remove xattr, error %d", err);
549 			goto out_err;
550 		}
551 
552 		iput(xino);
553 
554 		kfree(pxent);
555 		pxent = xent;
556 		key_read(c, &xent->key, &key);
557 	}
558 	kfree(pxent);
559 	up_write(&ubifs_inode(host)->xattr_sem);
560 
561 	if (err != -ENOENT) {
562 		ubifs_err(c, "cannot find next direntry, error %d", err);
563 		return err;
564 	}
565 
566 	return 0;
567 
568 out_err:
569 	up_write(&ubifs_inode(host)->xattr_sem);
570 	return err;
571 }
572 
573 /**
574  * ubifs_evict_xattr_inode - Evict an xattr inode.
575  * @c: UBIFS file-system description object
576  * @xattr_inum: xattr inode number
577  *
578  * When an inode that hosts xattrs is being removed we have to make sure
579  * that cached inodes of the xattrs also get removed from the inode cache
580  * otherwise we'd waste memory. This function looks up an inode from the
581  * inode cache and clears the link counter such that iput() will evict
582  * the inode.
583  */
ubifs_evict_xattr_inode(struct ubifs_info * c,ino_t xattr_inum)584 void ubifs_evict_xattr_inode(struct ubifs_info *c, ino_t xattr_inum)
585 {
586 	struct inode *inode;
587 
588 	inode = ilookup(c->vfs_sb, xattr_inum);
589 	if (inode) {
590 		clear_nlink(inode);
591 		iput(inode);
592 	}
593 }
594 
ubifs_xattr_remove(struct inode * host,const char * name)595 static int ubifs_xattr_remove(struct inode *host, const char *name)
596 {
597 	struct inode *inode;
598 	struct ubifs_info *c = host->i_sb->s_fs_info;
599 	struct fscrypt_name nm = { .disk_name = FSTR_INIT((char *)name, strlen(name))};
600 	struct ubifs_dent_node *xent;
601 	union ubifs_key key;
602 	int err;
603 
604 	ubifs_assert(c, inode_is_locked(host));
605 
606 	if (fname_len(&nm) > UBIFS_MAX_NLEN)
607 		return -ENAMETOOLONG;
608 
609 	xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
610 	if (!xent)
611 		return -ENOMEM;
612 
613 	down_write(&ubifs_inode(host)->xattr_sem);
614 	xent_key_init(c, &key, host->i_ino, &nm);
615 	err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
616 	if (err) {
617 		if (err == -ENOENT)
618 			err = -ENODATA;
619 		goto out_free;
620 	}
621 
622 	inode = iget_xattr(c, le64_to_cpu(xent->inum));
623 	if (IS_ERR(inode)) {
624 		err = PTR_ERR(inode);
625 		goto out_free;
626 	}
627 
628 	ubifs_assert(c, inode->i_nlink == 1);
629 	clear_nlink(inode);
630 	err = remove_xattr(c, host, inode, &nm);
631 	if (err)
632 		set_nlink(inode, 1);
633 
634 	/* If @i_nlink is 0, 'iput()' will delete the inode */
635 	iput(inode);
636 
637 out_free:
638 	up_write(&ubifs_inode(host)->xattr_sem);
639 	kfree(xent);
640 	return err;
641 }
642 
643 #ifdef CONFIG_UBIFS_FS_SECURITY
init_xattrs(struct inode * inode,const struct xattr * xattr_array,void * fs_info)644 static int init_xattrs(struct inode *inode, const struct xattr *xattr_array,
645 		      void *fs_info)
646 {
647 	const struct xattr *xattr;
648 	char *name;
649 	int err = 0;
650 
651 	for (xattr = xattr_array; xattr->name != NULL; xattr++) {
652 		name = kmalloc(XATTR_SECURITY_PREFIX_LEN +
653 			       strlen(xattr->name) + 1, GFP_NOFS);
654 		if (!name) {
655 			err = -ENOMEM;
656 			break;
657 		}
658 		strcpy(name, XATTR_SECURITY_PREFIX);
659 		strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
660 		/*
661 		 * creating a new inode without holding the inode rwsem,
662 		 * no need to check whether inode is locked.
663 		 */
664 		err = ubifs_xattr_set(inode, name, xattr->value,
665 				      xattr->value_len, 0, false);
666 		kfree(name);
667 		if (err < 0)
668 			break;
669 	}
670 
671 	return err;
672 }
673 
ubifs_init_security(struct inode * dentry,struct inode * inode,const struct qstr * qstr)674 int ubifs_init_security(struct inode *dentry, struct inode *inode,
675 			const struct qstr *qstr)
676 {
677 	int err;
678 
679 	err = security_inode_init_security(inode, dentry, qstr,
680 					   &init_xattrs, NULL);
681 	if (err) {
682 		struct ubifs_info *c = dentry->i_sb->s_fs_info;
683 		ubifs_err(c, "cannot initialize security for inode %lu, error %d",
684 			  inode->i_ino, err);
685 	}
686 	return err;
687 }
688 #endif
689 
xattr_get(const struct xattr_handler * handler,struct dentry * dentry,struct inode * inode,const char * name,void * buffer,size_t size)690 static int xattr_get(const struct xattr_handler *handler,
691 			   struct dentry *dentry, struct inode *inode,
692 			   const char *name, void *buffer, size_t size)
693 {
694 	dbg_gen("xattr '%s', ino %lu ('%pd'), buf size %zd", name,
695 		inode->i_ino, dentry, size);
696 
697 	name = xattr_full_name(handler, name);
698 	return ubifs_xattr_get(inode, name, buffer, size);
699 }
700 
xattr_set(const struct xattr_handler * handler,struct mnt_idmap * idmap,struct dentry * dentry,struct inode * inode,const char * name,const void * value,size_t size,int flags)701 static int xattr_set(const struct xattr_handler *handler,
702 			   struct mnt_idmap *idmap,
703 			   struct dentry *dentry, struct inode *inode,
704 			   const char *name, const void *value,
705 			   size_t size, int flags)
706 {
707 	dbg_gen("xattr '%s', host ino %lu ('%pd'), size %zd",
708 		name, inode->i_ino, dentry, size);
709 
710 	name = xattr_full_name(handler, name);
711 
712 	if (value)
713 		return ubifs_xattr_set(inode, name, value, size, flags, true);
714 	else
715 		return ubifs_xattr_remove(inode, name);
716 }
717 
718 static const struct xattr_handler ubifs_user_xattr_handler = {
719 	.prefix = XATTR_USER_PREFIX,
720 	.get = xattr_get,
721 	.set = xattr_set,
722 };
723 
724 static const struct xattr_handler ubifs_trusted_xattr_handler = {
725 	.prefix = XATTR_TRUSTED_PREFIX,
726 	.get = xattr_get,
727 	.set = xattr_set,
728 };
729 
730 #ifdef CONFIG_UBIFS_FS_SECURITY
731 static const struct xattr_handler ubifs_security_xattr_handler = {
732 	.prefix = XATTR_SECURITY_PREFIX,
733 	.get = xattr_get,
734 	.set = xattr_set,
735 };
736 #endif
737 
738 const struct xattr_handler *ubifs_xattr_handlers[] = {
739 	&ubifs_user_xattr_handler,
740 	&ubifs_trusted_xattr_handler,
741 #ifdef CONFIG_UBIFS_FS_SECURITY
742 	&ubifs_security_xattr_handler,
743 #endif
744 	NULL
745 };
746