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