1 // SPDX-License-Identifier: GPL-2.0-only 1
2 /*
3 * linux/fs/msdos/namei.c
4 *
5 * Written 1992,1993 by Werner Almesberger
6 * Hidden files 1995 by Albert Cahalan <alber
7 * Rewritten for constant inumbers 1999 by Al
8 */
9
10 #include <linux/module.h>
11 #include <linux/iversion.h>
12 #include "fat.h"
13
14 /* Characters that are undesirable in an MS-DO
15 static unsigned char bad_chars[] = "*?<>|\"";
16 static unsigned char bad_if_strict[] = "+=,; "
17
18 /***** Formats an MS-DOS file name. Rejects in
19 static int msdos_format_name(const unsigned ch
20 unsigned char *re
21 /*
22 * name is the proposed name, len is i
23 * the resulting name, opts->name_chec
24 * (n)ormal or (s)trict, opts->dotsOK
25 * beginning of name (for hidden files
26 */
27 {
28 unsigned char *walk;
29 unsigned char c;
30 int space;
31
32 if (name[0] == '.') { /* dotfile bec
33 if (opts->dotsOK) {
34 /* Get rid of dot - te
35 name++;
36 len--;
37 } else
38 return -EINVAL;
39 }
40 /*
41 * disallow names that _really_ start
42 */
43 space = 1;
44 c = 0;
45 for (walk = res; len && walk - res < 8
46 c = *name++;
47 len--;
48 if (opts->name_check != 'r' &&
49 return -EINVAL;
50 if (opts->name_check == 's' &&
51 return -EINVAL;
52 if (c >= 'A' && c <= 'Z' && op
53 return -EINVAL;
54 if (c < ' ' || c == ':' || c =
55 return -EINVAL;
56 /*
57 * 0xE5 is legal as a first character,
58 * 0x05 because 0xE5 marks deleted fil
59 * does this.
60 * It seems that Microsoft hacked DOS
61 * characters after the 0xE5 character
62 * mark deleted files.
63 */
64 if ((res == walk) && (c == 0xE
65 c = 0x05;
66 if (c == '.')
67 break;
68 space = (c == ' ');
69 *walk = (!opts->nocase && c >=
70 }
71 if (space)
72 return -EINVAL;
73 if (opts->name_check == 's' && len &&
74 c = *name++;
75 len--;
76 if (c != '.')
77 return -EINVAL;
78 }
79 while (c != '.' && len--)
80 c = *name++;
81 if (c == '.') {
82 while (walk - res < 8)
83 *walk++ = ' ';
84 while (len > 0 && walk - res <
85 c = *name++;
86 len--;
87 if (opts->name_check !
88 return -EINVAL
89 if (opts->name_check =
90 strchr(bad_if_stri
91 return -EINVAL
92 if (c < ' ' || c == ':
93 return -EINVAL
94 if (c == '.') {
95 if (opts->name
96 return
97 break;
98 }
99 if (c >= 'A' && c <= '
100 return -EINVAL
101 space = c == ' ';
102 if (!opts->nocase && c
103 *walk++ = c -
104 else
105 *walk++ = c;
106 }
107 if (space)
108 return -EINVAL;
109 if (opts->name_check == 's' &&
110 return -EINVAL;
111 }
112 while (walk - res < MSDOS_NAME)
113 *walk++ = ' ';
114
115 return 0;
116 }
117
118 /***** Locates a directory entry. Uses unform
119 static int msdos_find(struct inode *dir, const
120 struct fat_slot_info *si
121 {
122 struct msdos_sb_info *sbi = MSDOS_SB(d
123 unsigned char msdos_name[MSDOS_NAME];
124 int err;
125
126 err = msdos_format_name(name, len, msd
127 if (err)
128 return -ENOENT;
129
130 err = fat_scan(dir, msdos_name, sinfo)
131 if (!err && sbi->options.dotsOK) {
132 if (name[0] == '.') {
133 if (!(sinfo->de->attr
134 err = -ENOENT;
135 } else {
136 if (sinfo->de->attr &
137 err = -ENOENT;
138 }
139 if (err)
140 brelse(sinfo->bh);
141 }
142 return err;
143 }
144
145 /*
146 * Compute the hash for the msdos name corresp
147 * Note: if the name is invalid, we leave the
148 * that the existing dentry can be used. The m
149 * return ENOENT or EINVAL as appropriate.
150 */
151 static int msdos_hash(const struct dentry *den
152 {
153 struct fat_mount_options *options = &M
154 unsigned char msdos_name[MSDOS_NAME];
155 int error;
156
157 error = msdos_format_name(qstr->name,
158 if (!error)
159 qstr->hash = full_name_hash(de
160 return 0;
161 }
162
163 /*
164 * Compare two msdos names. If either of the n
165 * we fall back to doing the standard name com
166 */
167 static int msdos_cmp(const struct dentry *dent
168 unsigned int len, const char *
169 {
170 struct fat_mount_options *options = &M
171 unsigned char a_msdos_name[MSDOS_NAME]
172 int error;
173
174 error = msdos_format_name(name->name,
175 if (error)
176 goto old_compare;
177 error = msdos_format_name(str, len, b_
178 if (error)
179 goto old_compare;
180 error = memcmp(a_msdos_name, b_msdos_n
181 out:
182 return error;
183
184 old_compare:
185 error = 1;
186 if (name->len == len)
187 error = memcmp(name->name, str
188 goto out;
189 }
190
191 static const struct dentry_operations msdos_de
192 .d_hash = msdos_hash,
193 .d_compare = msdos_cmp,
194 };
195
196 /*
197 * AV. Wrappers for FAT sb operations. Is it w
198 */
199
200 /***** Get inode using directory and name */
201 static struct dentry *msdos_lookup(struct inod
202 unsigned in
203 {
204 struct super_block *sb = dir->i_sb;
205 struct fat_slot_info sinfo;
206 struct inode *inode;
207 int err;
208
209 mutex_lock(&MSDOS_SB(sb)->s_lock);
210 err = msdos_find(dir, dentry->d_name.n
211 switch (err) {
212 case -ENOENT:
213 inode = NULL;
214 break;
215 case 0:
216 inode = fat_build_inode(sb, si
217 brelse(sinfo.bh);
218 break;
219 default:
220 inode = ERR_PTR(err);
221 }
222 mutex_unlock(&MSDOS_SB(sb)->s_lock);
223 return d_splice_alias(inode, dentry);
224 }
225
226 /***** Creates a directory entry (name is alre
227 static int msdos_add_entry(struct inode *dir,
228 int is_dir, int is_
229 struct timespec64 *
230 {
231 struct msdos_sb_info *sbi = MSDOS_SB(d
232 struct msdos_dir_entry de;
233 __le16 time, date;
234 int err;
235
236 memcpy(de.name, name, MSDOS_NAME);
237 de.attr = is_dir ? ATTR_DIR : ATTR_ARC
238 if (is_hid)
239 de.attr |= ATTR_HIDDEN;
240 de.lcase = 0;
241 fat_time_unix2fat(sbi, ts, &time, &dat
242 de.cdate = de.adate = 0;
243 de.ctime = 0;
244 de.ctime_cs = 0;
245 de.time = time;
246 de.date = date;
247 fat_set_start(&de, cluster);
248 de.size = 0;
249
250 err = fat_add_entries(dir, &de, 1, sin
251 if (err)
252 return err;
253
254 fat_truncate_time(dir, ts, S_CTIME|S_M
255 if (IS_DIRSYNC(dir))
256 (void)fat_sync_inode(dir);
257 else
258 mark_inode_dirty(dir);
259
260 return 0;
261 }
262
263 /***** Create a file */
264 static int msdos_create(struct mnt_idmap *idma
265 struct dentry *dentry,
266 {
267 struct super_block *sb = dir->i_sb;
268 struct inode *inode = NULL;
269 struct fat_slot_info sinfo;
270 struct timespec64 ts;
271 unsigned char msdos_name[MSDOS_NAME];
272 int err, is_hid;
273
274 mutex_lock(&MSDOS_SB(sb)->s_lock);
275
276 err = msdos_format_name(dentry->d_name
277 msdos_name, &M
278 if (err)
279 goto out;
280 is_hid = (dentry->d_name.name[0] == '.
281 /* Have to do it due to foo vs. .foo c
282 if (!fat_scan(dir, msdos_name, &sinfo)
283 brelse(sinfo.bh);
284 err = -EINVAL;
285 goto out;
286 }
287
288 ts = current_time(dir);
289 err = msdos_add_entry(dir, msdos_name,
290 if (err)
291 goto out;
292 inode = fat_build_inode(sb, sinfo.de,
293 brelse(sinfo.bh);
294 if (IS_ERR(inode)) {
295 err = PTR_ERR(inode);
296 goto out;
297 }
298 fat_truncate_time(inode, &ts, S_ATIME|
299 /* timestamp is already written, so ma
300
301 d_instantiate(dentry, inode);
302 out:
303 mutex_unlock(&MSDOS_SB(sb)->s_lock);
304 if (!err)
305 err = fat_flush_inodes(sb, dir
306 return err;
307 }
308
309 /***** Remove a directory */
310 static int msdos_rmdir(struct inode *dir, stru
311 {
312 struct super_block *sb = dir->i_sb;
313 struct inode *inode = d_inode(dentry);
314 struct fat_slot_info sinfo;
315 int err;
316
317 mutex_lock(&MSDOS_SB(sb)->s_lock);
318 err = fat_dir_empty(inode);
319 if (err)
320 goto out;
321 err = msdos_find(dir, dentry->d_name.n
322 if (err)
323 goto out;
324
325 err = fat_remove_entries(dir, &sinfo);
326 if (err)
327 goto out;
328 drop_nlink(dir);
329
330 clear_nlink(inode);
331 fat_truncate_time(inode, NULL, S_CTIME
332 fat_detach(inode);
333 out:
334 mutex_unlock(&MSDOS_SB(sb)->s_lock);
335 if (!err)
336 err = fat_flush_inodes(sb, dir
337
338 return err;
339 }
340
341 /***** Make a directory */
342 static int msdos_mkdir(struct mnt_idmap *idmap
343 struct dentry *dentry,
344 {
345 struct super_block *sb = dir->i_sb;
346 struct fat_slot_info sinfo;
347 struct inode *inode;
348 unsigned char msdos_name[MSDOS_NAME];
349 struct timespec64 ts;
350 int err, is_hid, cluster;
351
352 mutex_lock(&MSDOS_SB(sb)->s_lock);
353
354 err = msdos_format_name(dentry->d_name
355 msdos_name, &M
356 if (err)
357 goto out;
358 is_hid = (dentry->d_name.name[0] == '.
359 /* foo vs .foo situation */
360 if (!fat_scan(dir, msdos_name, &sinfo)
361 brelse(sinfo.bh);
362 err = -EINVAL;
363 goto out;
364 }
365
366 ts = current_time(dir);
367 cluster = fat_alloc_new_dir(dir, &ts);
368 if (cluster < 0) {
369 err = cluster;
370 goto out;
371 }
372 err = msdos_add_entry(dir, msdos_name,
373 if (err)
374 goto out_free;
375 inc_nlink(dir);
376
377 inode = fat_build_inode(sb, sinfo.de,
378 brelse(sinfo.bh);
379 if (IS_ERR(inode)) {
380 err = PTR_ERR(inode);
381 /* the directory was completed
382 goto out;
383 }
384 set_nlink(inode, 2);
385 fat_truncate_time(inode, &ts, S_ATIME|
386 /* timestamp is already written, so ma
387
388 d_instantiate(dentry, inode);
389
390 mutex_unlock(&MSDOS_SB(sb)->s_lock);
391 fat_flush_inodes(sb, dir, inode);
392 return 0;
393
394 out_free:
395 fat_free_clusters(dir, cluster);
396 out:
397 mutex_unlock(&MSDOS_SB(sb)->s_lock);
398 return err;
399 }
400
401 /***** Unlink a file */
402 static int msdos_unlink(struct inode *dir, str
403 {
404 struct inode *inode = d_inode(dentry);
405 struct super_block *sb = inode->i_sb;
406 struct fat_slot_info sinfo;
407 int err;
408
409 mutex_lock(&MSDOS_SB(sb)->s_lock);
410 err = msdos_find(dir, dentry->d_name.n
411 if (err)
412 goto out;
413
414 err = fat_remove_entries(dir, &sinfo);
415 if (err)
416 goto out;
417 clear_nlink(inode);
418 fat_truncate_time(inode, NULL, S_CTIME
419 fat_detach(inode);
420 out:
421 mutex_unlock(&MSDOS_SB(sb)->s_lock);
422 if (!err)
423 err = fat_flush_inodes(sb, dir
424
425 return err;
426 }
427
428 static int do_msdos_rename(struct inode *old_d
429 struct dentry *old_
430 struct inode *new_d
431 struct dentry *new_
432 {
433 struct buffer_head *dotdot_bh;
434 struct msdos_dir_entry *dotdot_de;
435 struct inode *old_inode, *new_inode;
436 struct fat_slot_info old_sinfo, sinfo;
437 struct timespec64 ts;
438 loff_t new_i_pos;
439 int err, old_attrs, is_dir, update_dot
440
441 old_sinfo.bh = sinfo.bh = dotdot_bh =
442 old_inode = d_inode(old_dentry);
443 new_inode = d_inode(new_dentry);
444
445 err = fat_scan(old_dir, old_name, &old
446 if (err) {
447 err = -EIO;
448 goto out;
449 }
450
451 is_dir = S_ISDIR(old_inode->i_mode);
452 update_dotdot = (is_dir && old_dir !=
453 if (update_dotdot) {
454 if (fat_get_dotdot_entry(old_i
455 err = -EIO;
456 goto out;
457 }
458 }
459
460 old_attrs = MSDOS_I(old_inode)->i_attr
461 err = fat_scan(new_dir, new_name, &sin
462 if (!err) {
463 if (!new_inode) {
464 /* "foo" -> ".foo" cas
465 if (sinfo.de != old_si
466 err = -EINVAL;
467 goto out;
468 }
469 if (is_hid)
470 MSDOS_I(old_in
471 else
472 MSDOS_I(old_in
473 if (IS_DIRSYNC(old_dir
474 err = fat_sync
475 if (err) {
476 MSDOS_
477 goto o
478 }
479 } else
480 mark_inode_dir
481
482 inode_inc_iversion(old
483 fat_truncate_time(old_
484 if (IS_DIRSYNC(old_dir
485 (void)fat_sync
486 else
487 mark_inode_dir
488 goto out;
489 }
490 }
491
492 ts = current_time(old_inode);
493 if (new_inode) {
494 if (err)
495 goto out;
496 if (is_dir) {
497 err = fat_dir_empty(ne
498 if (err)
499 goto out;
500 }
501 new_i_pos = MSDOS_I(new_inode)
502 fat_detach(new_inode);
503 } else {
504 err = msdos_add_entry(new_dir,
505 &ts, &si
506 if (err)
507 goto out;
508 new_i_pos = sinfo.i_pos;
509 }
510 inode_inc_iversion(new_dir);
511
512 fat_detach(old_inode);
513 fat_attach(old_inode, new_i_pos);
514 if (is_hid)
515 MSDOS_I(old_inode)->i_attrs |=
516 else
517 MSDOS_I(old_inode)->i_attrs &=
518 if (IS_DIRSYNC(new_dir)) {
519 err = fat_sync_inode(old_inode
520 if (err)
521 goto error_inode;
522 } else
523 mark_inode_dirty(old_inode);
524
525 if (update_dotdot) {
526 fat_set_start(dotdot_de, MSDOS
527 mark_buffer_dirty_inode(dotdot
528 if (IS_DIRSYNC(new_dir)) {
529 err = sync_dirty_buffe
530 if (err)
531 goto error_dot
532 }
533 drop_nlink(old_dir);
534 if (!new_inode)
535 inc_nlink(new_dir);
536 }
537
538 err = fat_remove_entries(old_dir, &old
539 old_sinfo.bh = NULL;
540 if (err)
541 goto error_dotdot;
542 inode_inc_iversion(old_dir);
543 fat_truncate_time(old_dir, &ts, S_CTIM
544 if (IS_DIRSYNC(old_dir))
545 (void)fat_sync_inode(old_dir);
546 else
547 mark_inode_dirty(old_dir);
548
549 if (new_inode) {
550 drop_nlink(new_inode);
551 if (is_dir)
552 drop_nlink(new_inode);
553 fat_truncate_time(new_inode, &
554 }
555 out:
556 brelse(sinfo.bh);
557 brelse(dotdot_bh);
558 brelse(old_sinfo.bh);
559 return err;
560
561 error_dotdot:
562 /* data cluster is shared, serious cor
563 corrupt = 1;
564
565 if (update_dotdot) {
566 fat_set_start(dotdot_de, MSDOS
567 mark_buffer_dirty_inode(dotdot
568 corrupt |= sync_dirty_buffer(d
569 }
570 error_inode:
571 fat_detach(old_inode);
572 fat_attach(old_inode, old_sinfo.i_pos)
573 MSDOS_I(old_inode)->i_attrs = old_attr
574 if (new_inode) {
575 fat_attach(new_inode, new_i_po
576 if (corrupt)
577 corrupt |= fat_sync_in
578 } else {
579 /*
580 * If new entry was not sharin
581 * shouldn't be serious corrup
582 */
583 int err2 = fat_remove_entries(
584 if (corrupt)
585 corrupt |= err2;
586 sinfo.bh = NULL;
587 }
588 if (corrupt < 0) {
589 fat_fs_error(new_dir->i_sb,
590 "%s: Filesystem c
591 __func__, sinfo.i
592 }
593 goto out;
594 }
595
596 /***** Rename, a wrapper for rename_same_dir &
597 static int msdos_rename(struct mnt_idmap *idma
598 struct inode *old_dir,
599 struct inode *new_dir,
600 unsigned int flags)
601 {
602 struct super_block *sb = old_dir->i_sb
603 unsigned char old_msdos_name[MSDOS_NAM
604 int err, is_hid;
605
606 if (flags & ~RENAME_NOREPLACE)
607 return -EINVAL;
608
609 mutex_lock(&MSDOS_SB(sb)->s_lock);
610
611 err = msdos_format_name(old_dentry->d_
612 old_dentry->d_
613 &MSDOS_SB(old_
614 if (err)
615 goto out;
616 err = msdos_format_name(new_dentry->d_
617 new_dentry->d_
618 &MSDOS_SB(new_
619 if (err)
620 goto out;
621
622 is_hid =
623 (new_dentry->d_name.name[0] == '.
624
625 err = do_msdos_rename(old_dir, old_msd
626 new_dir, new_msd
627 out:
628 mutex_unlock(&MSDOS_SB(sb)->s_lock);
629 if (!err)
630 err = fat_flush_inodes(sb, old
631 return err;
632 }
633
634 static const struct inode_operations msdos_dir
635 .create = msdos_create,
636 .lookup = msdos_lookup,
637 .unlink = msdos_unlink,
638 .mkdir = msdos_mkdir,
639 .rmdir = msdos_rmdir,
640 .rename = msdos_rename,
641 .setattr = fat_setattr,
642 .getattr = fat_getattr,
643 .update_time = fat_update_time,
644 };
645
646 static void setup(struct super_block *sb)
647 {
648 MSDOS_SB(sb)->dir_ops = &msdos_dir_ino
649 sb->s_d_op = &msdos_dentry_operations;
650 sb->s_flags |= SB_NOATIME;
651 }
652
653 static int msdos_fill_super(struct super_block
654 {
655 return fat_fill_super(sb, fc, setup);
656 }
657
658 static int msdos_get_tree(struct fs_context *f
659 {
660 return get_tree_bdev(fc, msdos_fill_su
661 }
662
663 static int msdos_parse_param(struct fs_context
664 {
665 return fat_parse_param(fc, param, fals
666 }
667
668 static const struct fs_context_operations msdo
669 .parse_param = msdos_parse_param,
670 .get_tree = msdos_get_tree,
671 .reconfigure = fat_reconfigure,
672 .free = fat_free_fc,
673 };
674
675 static int msdos_init_fs_context(struct fs_con
676 {
677 int err;
678
679 /* Initialize with is_vfat == false */
680 err = fat_init_fs_context(fc, false);
681 if (err)
682 return err;
683
684 fc->ops = &msdos_context_ops;
685 return 0;
686 }
687
688 static struct file_system_type msdos_fs_type =
689 .owner = THIS_MODULE,
690 .name = "msdos",
691 .kill_sb = kill_block_super,
692 .fs_flags = FS_REQUIRES_DEV | FS
693 .init_fs_context = msdos_init_fs_conte
694 .parameters = fat_param_spec,
695 };
696 MODULE_ALIAS_FS("msdos");
697
698 static int __init init_msdos_fs(void)
699 {
700 return register_filesystem(&msdos_fs_t
701 }
702
703 static void __exit exit_msdos_fs(void)
704 {
705 unregister_filesystem(&msdos_fs_type);
706 }
707
708 MODULE_LICENSE("GPL");
709 MODULE_AUTHOR("Werner Almesberger");
710 MODULE_DESCRIPTION("MS-DOS filesystem support"
711
712 module_init(init_msdos_fs)
713 module_exit(exit_msdos_fs)
714
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