1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/fs/vfat/namei.c
4 *
5 * Written 1992,1993 by Werner Almesberger
6 *
7 * Windows95/Windows NT compatible extended MSDOS filesystem
8 * by Gordon Chaffee Copyright (C) 1995. Send bug reports for the
9 * VFAT filesystem to <chaffee@cs.berkeley.edu>. Specify
10 * what file operation caused you trouble and if you can duplicate
11 * the problem, send a script that demonstrates it.
12 *
13 * Short name translation 1999, 2001 by Wolfram Pienkoss <wp@bszh.de>
14 *
15 * Support Multibyte characters and cleanup by
16 * OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
17 */
18
19#include <linux/module.h>
20#include <linux/ctype.h>
21#include <linux/slab.h>
22#include <linux/namei.h>
23#include <linux/kernel.h>
24#include <linux/iversion.h>
25#include "fat.h"
26
27static inline unsigned long vfat_d_version(struct dentry *dentry)
28{
29 return (unsigned long) dentry->d_fsdata;
30}
31
32static inline void vfat_d_version_set(struct dentry *dentry,
33 unsigned long version)
34{
35 dentry->d_fsdata = (void *) version;
36}
37
38/*
39 * If new entry was created in the parent, it could create the 8.3
40 * alias (the shortname of logname). So, the parent may have the
41 * negative-dentry which matches the created 8.3 alias.
42 *
43 * If it happened, the negative dentry isn't actually negative
44 * anymore. So, drop it.
45 */
46static bool vfat_revalidate_shortname(struct dentry *dentry, struct inode *dir)
47{
48 return inode_eq_iversion(inode: dir, old: vfat_d_version(dentry));
49}
50
51static int vfat_revalidate(struct inode *dir, const struct qstr *name,
52 struct dentry *dentry, unsigned int flags)
53{
54 if (flags & LOOKUP_RCU)
55 return -ECHILD;
56
57 /* This is not negative dentry. Always valid. */
58 if (d_really_is_positive(dentry))
59 return 1;
60 return vfat_revalidate_shortname(dentry, dir);
61}
62
63static int vfat_revalidate_ci(struct inode *dir, const struct qstr *name,
64 struct dentry *dentry, unsigned int flags)
65{
66 if (flags & LOOKUP_RCU)
67 return -ECHILD;
68
69 /*
70 * This is not negative dentry. Always valid.
71 *
72 * Note, rename() to existing directory entry will have ->d_inode,
73 * and will use existing name which isn't specified name by user.
74 *
75 * We may be able to drop this positive dentry here. But dropping
76 * positive dentry isn't good idea. So it's unsupported like
77 * rename("filename", "FILENAME") for now.
78 */
79 if (d_really_is_positive(dentry))
80 return 1;
81
82 /*
83 * This may be nfsd (or something), anyway, we can't see the
84 * intent of this. So, since this can be for creation, drop it.
85 */
86 if (!flags)
87 return 0;
88
89 /*
90 * Drop the negative dentry, in order to make sure to use the
91 * case sensitive name which is specified by user if this is
92 * for creation.
93 */
94 if (flags & (LOOKUP_CREATE | LOOKUP_RENAME_TARGET))
95 return 0;
96
97 return vfat_revalidate_shortname(dentry, dir);
98}
99
100/* returns the length of a struct qstr, ignoring trailing dots */
101static unsigned int __vfat_striptail_len(unsigned int len, const char *name)
102{
103 while (len && name[len - 1] == '.')
104 len--;
105 return len;
106}
107
108static unsigned int vfat_striptail_len(const struct qstr *qstr)
109{
110 return __vfat_striptail_len(len: qstr->len, name: qstr->name);
111}
112
113/*
114 * Compute the hash for the vfat name corresponding to the dentry.
115 * Note: if the name is invalid, we leave the hash code unchanged so
116 * that the existing dentry can be used. The vfat fs routines will
117 * return ENOENT or EINVAL as appropriate.
118 */
119static int vfat_hash(const struct dentry *dentry, struct qstr *qstr)
120{
121 qstr->hash = full_name_hash(salt: dentry, qstr->name, vfat_striptail_len(qstr));
122 return 0;
123}
124
125/*
126 * Compute the hash for the vfat name corresponding to the dentry.
127 * Note: if the name is invalid, we leave the hash code unchanged so
128 * that the existing dentry can be used. The vfat fs routines will
129 * return ENOENT or EINVAL as appropriate.
130 */
131static int vfat_hashi(const struct dentry *dentry, struct qstr *qstr)
132{
133 struct nls_table *t = MSDOS_SB(sb: dentry->d_sb)->nls_io;
134 const unsigned char *name;
135 unsigned int len;
136 unsigned long hash;
137
138 name = qstr->name;
139 len = vfat_striptail_len(qstr);
140
141 hash = init_name_hash(dentry);
142 while (len--)
143 hash = partial_name_hash(c: nls_tolower(t, c: *name++), prevhash: hash);
144 qstr->hash = end_name_hash(hash);
145
146 return 0;
147}
148
149/*
150 * Case insensitive compare of two vfat names.
151 */
152static int vfat_cmpi(const struct dentry *dentry,
153 unsigned int len, const char *str, const struct qstr *name)
154{
155 struct nls_table *t = MSDOS_SB(sb: dentry->d_sb)->nls_io;
156 unsigned int alen, blen;
157
158 /* A filename cannot end in '.' or we treat it like it has none */
159 alen = vfat_striptail_len(qstr: name);
160 blen = __vfat_striptail_len(len, name: str);
161 if (alen == blen) {
162 if (nls_strnicmp(t, s1: name->name, s2: str, len: alen) == 0)
163 return 0;
164 }
165 return 1;
166}
167
168/*
169 * Case sensitive compare of two vfat names.
170 */
171static int vfat_cmp(const struct dentry *dentry,
172 unsigned int len, const char *str, const struct qstr *name)
173{
174 unsigned int alen, blen;
175
176 /* A filename cannot end in '.' or we treat it like it has none */
177 alen = vfat_striptail_len(qstr: name);
178 blen = __vfat_striptail_len(len, name: str);
179 if (alen == blen) {
180 if (strncmp(name->name, str, alen) == 0)
181 return 0;
182 }
183 return 1;
184}
185
186static const struct dentry_operations vfat_ci_dentry_ops = {
187 .d_revalidate = vfat_revalidate_ci,
188 .d_hash = vfat_hashi,
189 .d_compare = vfat_cmpi,
190};
191
192static const struct dentry_operations vfat_dentry_ops = {
193 .d_revalidate = vfat_revalidate,
194 .d_hash = vfat_hash,
195 .d_compare = vfat_cmp,
196};
197
198/* Characters that are undesirable in an MS-DOS file name */
199
200static inline bool vfat_bad_char(wchar_t w)
201{
202 return (w < 0x0020)
203 || (w == '*') || (w == '?') || (w == '<') || (w == '>')
204 || (w == '|') || (w == '"') || (w == ':') || (w == '/')
205 || (w == '\\');
206}
207
208static inline bool vfat_replace_char(wchar_t w)
209{
210 return (w == '[') || (w == ']') || (w == ';') || (w == ',')
211 || (w == '+') || (w == '=');
212}
213
214static wchar_t vfat_skip_char(wchar_t w)
215{
216 return (w == '.') || (w == ' ');
217}
218
219static inline int vfat_is_used_badchars(const wchar_t *s, int len)
220{
221 int i;
222
223 for (i = 0; i < len; i++)
224 if (vfat_bad_char(w: s[i]))
225 return -EINVAL;
226
227 if (s[i - 1] == ' ') /* last character cannot be space */
228 return -EINVAL;
229
230 return 0;
231}
232
233static int vfat_find_form(struct inode *dir, unsigned char *name)
234{
235 struct fat_slot_info sinfo;
236 int err = fat_scan(dir, name, sinfo: &sinfo);
237 if (err)
238 return -ENOENT;
239 brelse(bh: sinfo.bh);
240 return 0;
241}
242
243/*
244 * 1) Valid characters for the 8.3 format alias are any combination of
245 * letters, uppercase alphabets, digits, any of the
246 * following special characters:
247 * $ % ' ` - @ { } ~ ! # ( ) & _ ^
248 * In this case Longfilename is not stored in disk.
249 *
250 * WinNT's Extension:
251 * File name and extension name is contain uppercase/lowercase
252 * only. And it is expressed by CASE_LOWER_BASE and CASE_LOWER_EXT.
253 *
254 * 2) File name is 8.3 format, but it contain the uppercase and
255 * lowercase char, muliti bytes char, etc. In this case numtail is not
256 * added, but Longfilename is stored.
257 *
258 * 3) When the one except for the above, or the following special
259 * character are contained:
260 * . [ ] ; , + =
261 * numtail is added, and Longfilename must be stored in disk .
262 */
263struct shortname_info {
264 unsigned char lower:1,
265 upper:1,
266 valid:1;
267};
268#define INIT_SHORTNAME_INFO(x) do { \
269 (x)->lower = 1; \
270 (x)->upper = 1; \
271 (x)->valid = 1; \
272} while (0)
273
274static inline int to_shortname_char(struct nls_table *nls,
275 unsigned char *buf, int buf_size,
276 wchar_t *src, struct shortname_info *info)
277{
278 int len;
279
280 if (vfat_skip_char(w: *src)) {
281 info->valid = 0;
282 return 0;
283 }
284 if (vfat_replace_char(w: *src)) {
285 info->valid = 0;
286 buf[0] = '_';
287 return 1;
288 }
289
290 len = nls->uni2char(*src, buf, buf_size);
291 if (len <= 0) {
292 info->valid = 0;
293 buf[0] = '_';
294 len = 1;
295 } else if (len == 1) {
296 unsigned char prev = buf[0];
297
298 if (buf[0] >= 0x7F) {
299 info->lower = 0;
300 info->upper = 0;
301 }
302
303 buf[0] = nls_toupper(t: nls, c: buf[0]);
304 if (isalpha(buf[0])) {
305 if (buf[0] == prev)
306 info->lower = 0;
307 else
308 info->upper = 0;
309 }
310 } else {
311 info->lower = 0;
312 info->upper = 0;
313 }
314
315 return len;
316}
317
318/*
319 * Given a valid longname, create a unique shortname. Make sure the
320 * shortname does not exist
321 * Returns negative number on error, 0 for a normal
322 * return, and 1 for valid shortname
323 */
324static int vfat_create_shortname(struct inode *dir, struct nls_table *nls,
325 wchar_t *uname, int ulen,
326 unsigned char *name_res, unsigned char *lcase)
327{
328 struct fat_mount_options *opts = &MSDOS_SB(sb: dir->i_sb)->options;
329 wchar_t *ip, *ext_start, *end, *name_start;
330 unsigned char base[9], ext[4], buf[5], *p;
331 unsigned char charbuf[NLS_MAX_CHARSET_SIZE];
332 int chl, chi;
333 int sz = 0, extlen, baselen, i, numtail_baselen, numtail2_baselen;
334 int is_shortname;
335 struct shortname_info base_info, ext_info;
336
337 is_shortname = 1;
338 INIT_SHORTNAME_INFO(&base_info);
339 INIT_SHORTNAME_INFO(&ext_info);
340
341 /* Now, we need to create a shortname from the long name */
342 ext_start = end = &uname[ulen];
343 while (--ext_start >= uname) {
344 if (*ext_start == 0x002E) { /* is `.' */
345 if (ext_start == end - 1) {
346 sz = ulen;
347 ext_start = NULL;
348 }
349 break;
350 }
351 }
352
353 if (ext_start == uname - 1) {
354 sz = ulen;
355 ext_start = NULL;
356 } else if (ext_start) {
357 /*
358 * Names which start with a dot could be just
359 * an extension eg. "...test". In this case Win95
360 * uses the extension as the name and sets no extension.
361 */
362 name_start = &uname[0];
363 while (name_start < ext_start) {
364 if (!vfat_skip_char(w: *name_start))
365 break;
366 name_start++;
367 }
368 if (name_start != ext_start) {
369 sz = ext_start - uname;
370 ext_start++;
371 } else {
372 sz = ulen;
373 ext_start = NULL;
374 }
375 }
376
377 numtail_baselen = 6;
378 numtail2_baselen = 2;
379 for (baselen = i = 0, p = base, ip = uname; i < sz; i++, ip++) {
380 chl = to_shortname_char(nls, buf: charbuf, buf_size: sizeof(charbuf),
381 src: ip, info: &base_info);
382 if (chl == 0)
383 continue;
384
385 if (baselen < 2 && (baselen + chl) > 2)
386 numtail2_baselen = baselen;
387 if (baselen < 6 && (baselen + chl) > 6)
388 numtail_baselen = baselen;
389 for (chi = 0; chi < chl; chi++) {
390 *p++ = charbuf[chi];
391 baselen++;
392 if (baselen >= 8)
393 break;
394 }
395 if (baselen >= 8) {
396 if ((chi < chl - 1) || (ip + 1) - uname < sz)
397 is_shortname = 0;
398 break;
399 }
400 }
401 if (baselen == 0) {
402 return -EINVAL;
403 }
404
405 extlen = 0;
406 if (ext_start) {
407 for (p = ext, ip = ext_start; extlen < 3 && ip < end; ip++) {
408 chl = to_shortname_char(nls, buf: charbuf, buf_size: sizeof(charbuf),
409 src: ip, info: &ext_info);
410 if (chl == 0)
411 continue;
412
413 if ((extlen + chl) > 3) {
414 is_shortname = 0;
415 break;
416 }
417 for (chi = 0; chi < chl; chi++) {
418 *p++ = charbuf[chi];
419 extlen++;
420 }
421 if (extlen >= 3) {
422 if (ip + 1 != end)
423 is_shortname = 0;
424 break;
425 }
426 }
427 }
428 ext[extlen] = '\0';
429 base[baselen] = '\0';
430
431 /* Yes, it can happen. ".\xe5" would do it. */
432 if (base[0] == DELETED_FLAG)
433 base[0] = 0x05;
434
435 /* OK, at this point we know that base is not longer than 8 symbols,
436 * ext is not longer than 3, base is nonempty, both don't contain
437 * any bad symbols (lowercase transformed to uppercase).
438 */
439
440 memset(s: name_res, c: ' ', MSDOS_NAME);
441 memcpy(to: name_res, from: base, len: baselen);
442 memcpy(to: name_res + 8, from: ext, len: extlen);
443 *lcase = 0;
444 if (is_shortname && base_info.valid && ext_info.valid) {
445 if (vfat_find_form(dir, name: name_res) == 0)
446 return -EEXIST;
447
448 if (opts->shortname & VFAT_SFN_CREATE_WIN95) {
449 return (base_info.upper && ext_info.upper);
450 } else if (opts->shortname & VFAT_SFN_CREATE_WINNT) {
451 if ((base_info.upper || base_info.lower) &&
452 (ext_info.upper || ext_info.lower)) {
453 if (!base_info.upper && base_info.lower)
454 *lcase |= CASE_LOWER_BASE;
455 if (!ext_info.upper && ext_info.lower)
456 *lcase |= CASE_LOWER_EXT;
457 return 1;
458 }
459 return 0;
460 } else {
461 BUG();
462 }
463 }
464
465 if (opts->numtail == 0)
466 if (vfat_find_form(dir, name: name_res) < 0)
467 return 0;
468
469 /*
470 * Try to find a unique extension. This used to
471 * iterate through all possibilities sequentially,
472 * but that gave extremely bad performance. Windows
473 * only tries a few cases before using random
474 * values for part of the base.
475 */
476
477 if (baselen > 6) {
478 baselen = numtail_baselen;
479 name_res[7] = ' ';
480 }
481 name_res[baselen] = '~';
482 for (i = 1; i < 10; i++) {
483 name_res[baselen + 1] = i + '0';
484 if (vfat_find_form(dir, name: name_res) < 0)
485 return 0;
486 }
487
488 i = jiffies;
489 sz = (jiffies >> 16) & 0x7;
490 if (baselen > 2) {
491 baselen = numtail2_baselen;
492 name_res[7] = ' ';
493 }
494 name_res[baselen + 4] = '~';
495 name_res[baselen + 5] = '1' + sz;
496 while (1) {
497 snprintf(buf, size: sizeof(buf), fmt: "%04X", i & 0xffff);
498 memcpy(to: &name_res[baselen], from: buf, len: 4);
499 if (vfat_find_form(dir, name: name_res) < 0)
500 break;
501 i -= 11;
502 }
503 return 0;
504}
505
506/* Translate a string, including coded sequences into Unicode */
507static int
508xlate_to_uni(const unsigned char *name, int len, unsigned char *outname,
509 int *longlen, int *outlen, int escape, int utf8,
510 struct nls_table *nls)
511{
512 const unsigned char *ip;
513 unsigned char *op;
514 int i, fill;
515 int charlen;
516
517 if (utf8) {
518 *outlen = utf8s_to_utf16s(s: name, len, endian: UTF16_HOST_ENDIAN,
519 pwcs: (wchar_t *) outname, FAT_LFN_LEN + 2);
520 if (*outlen < 0)
521 return *outlen;
522 else if (*outlen > FAT_LFN_LEN)
523 return -ENAMETOOLONG;
524
525 op = &outname[*outlen * sizeof(wchar_t)];
526 } else {
527 for (i = 0, ip = name, op = outname, *outlen = 0;
528 i < len && *outlen < FAT_LFN_LEN;
529 *outlen += 1) {
530 if (escape && (*ip == ':')) {
531 u8 uc[2];
532
533 if (i > len - 5)
534 return -EINVAL;
535
536 if (hex2bin(dst: uc, src: ip + 1, count: 2) < 0)
537 return -EINVAL;
538
539 *(wchar_t *)op = uc[0] << 8 | uc[1];
540
541 op += 2;
542 ip += 5;
543 i += 5;
544 } else {
545 charlen = nls->char2uni(ip, len - i,
546 (wchar_t *)op);
547 if (charlen < 0)
548 return -EINVAL;
549 ip += charlen;
550 i += charlen;
551 op += 2;
552 }
553 }
554 if (i < len)
555 return -ENAMETOOLONG;
556 }
557
558 *longlen = *outlen;
559 if (*outlen % 13) {
560 *op++ = 0;
561 *op++ = 0;
562 *outlen += 1;
563 if (*outlen % 13) {
564 fill = 13 - (*outlen % 13);
565 for (i = 0; i < fill; i++) {
566 *op++ = 0xff;
567 *op++ = 0xff;
568 }
569 *outlen += fill;
570 }
571 }
572
573 return 0;
574}
575
576static int vfat_build_slots(struct inode *dir, const unsigned char *name,
577 int len, int is_dir, int cluster,
578 struct timespec64 *ts,
579 struct msdos_dir_slot *slots, int *nr_slots)
580{
581 struct msdos_sb_info *sbi = MSDOS_SB(sb: dir->i_sb);
582 struct fat_mount_options *opts = &sbi->options;
583 struct msdos_dir_slot *ps;
584 struct msdos_dir_entry *de;
585 unsigned char cksum, lcase;
586 unsigned char msdos_name[MSDOS_NAME];
587 wchar_t *uname;
588 __le16 time, date;
589 u8 time_cs;
590 int err, ulen, usize, i;
591 loff_t offset;
592
593 *nr_slots = 0;
594
595 uname = __getname();
596 if (!uname)
597 return -ENOMEM;
598
599 err = xlate_to_uni(name, len, outname: (unsigned char *)uname, longlen: &ulen, outlen: &usize,
600 escape: opts->unicode_xlate, utf8: opts->utf8, nls: sbi->nls_io);
601 if (err)
602 goto out_free;
603
604 err = vfat_is_used_badchars(s: uname, len: ulen);
605 if (err)
606 goto out_free;
607
608 err = vfat_create_shortname(dir, nls: sbi->nls_disk, uname, ulen,
609 name_res: msdos_name, lcase: &lcase);
610 if (err < 0)
611 goto out_free;
612 else if (err == 1) {
613 de = (struct msdos_dir_entry *)slots;
614 err = 0;
615 goto shortname;
616 }
617
618 /* build the entry of long file name */
619 cksum = fat_checksum(name: msdos_name);
620
621 *nr_slots = usize / 13;
622 for (ps = slots, i = *nr_slots; i > 0; i--, ps++) {
623 ps->id = i;
624 ps->attr = ATTR_EXT;
625 ps->reserved = 0;
626 ps->alias_checksum = cksum;
627 ps->start = 0;
628 offset = (i - 1) * 13;
629 fatwchar_to16(dst: ps->name0_4, src: uname + offset, len: 5);
630 fatwchar_to16(dst: ps->name5_10, src: uname + offset + 5, len: 6);
631 fatwchar_to16(dst: ps->name11_12, src: uname + offset + 11, len: 2);
632 }
633 slots[0].id |= 0x40;
634 de = (struct msdos_dir_entry *)ps;
635
636shortname:
637 /* build the entry of 8.3 alias name */
638 (*nr_slots)++;
639 memcpy(to: de->name, from: msdos_name, MSDOS_NAME);
640 de->attr = is_dir ? ATTR_DIR : ATTR_ARCH;
641 de->lcase = lcase;
642 fat_time_unix2fat(sbi, ts, time: &time, date: &date, time_cs: &time_cs);
643 de->time = de->ctime = time;
644 de->date = de->cdate = de->adate = date;
645 de->ctime_cs = time_cs;
646 fat_set_start(de, cluster);
647 de->size = 0;
648out_free:
649 __putname(uname);
650 return err;
651}
652
653static int vfat_add_entry(struct inode *dir, const struct qstr *qname,
654 int is_dir, int cluster, struct timespec64 *ts,
655 struct fat_slot_info *sinfo)
656{
657 struct msdos_dir_slot *slots;
658 unsigned int len;
659 int err, nr_slots;
660
661 len = vfat_striptail_len(qstr: qname);
662 if (len == 0)
663 return -ENOENT;
664
665 slots = kmalloc_array(MSDOS_SLOTS, sizeof(*slots), GFP_NOFS);
666 if (slots == NULL)
667 return -ENOMEM;
668
669 err = vfat_build_slots(dir, name: qname->name, len, is_dir, cluster, ts,
670 slots, nr_slots: &nr_slots);
671 if (err)
672 goto cleanup;
673
674 err = fat_add_entries(dir, slots, nr_slots, sinfo);
675 if (err)
676 goto cleanup;
677
678 /* update timestamp */
679 fat_truncate_time(inode: dir, now: ts, flags: S_CTIME|S_MTIME);
680 if (IS_DIRSYNC(dir))
681 (void)fat_sync_inode(inode: dir);
682 else
683 mark_inode_dirty(inode: dir);
684cleanup:
685 kfree(objp: slots);
686 return err;
687}
688
689static int vfat_find(struct inode *dir, const struct qstr *qname,
690 struct fat_slot_info *sinfo)
691{
692 unsigned int len = vfat_striptail_len(qstr: qname);
693 if (len == 0)
694 return -ENOENT;
695 return fat_search_long(inode: dir, name: qname->name, name_len: len, sinfo);
696}
697
698static struct dentry *vfat_lookup(struct inode *dir, struct dentry *dentry,
699 unsigned int flags)
700{
701 struct super_block *sb = dir->i_sb;
702 struct fat_slot_info sinfo;
703 struct inode *inode;
704 struct dentry *alias;
705 int err;
706
707 mutex_lock(lock: &MSDOS_SB(sb)->s_lock);
708
709 err = vfat_find(dir, qname: &dentry->d_name, sinfo: &sinfo);
710 if (err) {
711 if (err == -ENOENT) {
712 inode = NULL;
713 goto out;
714 }
715 goto error;
716 }
717
718 inode = fat_build_inode(sb, de: sinfo.de, i_pos: sinfo.i_pos);
719 brelse(bh: sinfo.bh);
720 if (IS_ERR(ptr: inode)) {
721 err = PTR_ERR(ptr: inode);
722 goto error;
723 }
724
725 alias = d_find_alias(inode);
726 /*
727 * Checking "alias->d_parent == dentry->d_parent" to make sure
728 * FS is not corrupted (especially double linked dir).
729 */
730 if (alias && alias->d_parent == dentry->d_parent) {
731 /*
732 * This inode has non anonymous-DCACHE_DISCONNECTED
733 * dentry. This means, the user did ->lookup() by an
734 * another name (longname vs 8.3 alias of it) in past.
735 *
736 * Switch to new one for reason of locality if possible.
737 */
738 if (!S_ISDIR(inode->i_mode))
739 d_move(alias, dentry);
740 iput(inode);
741 mutex_unlock(lock: &MSDOS_SB(sb)->s_lock);
742 return alias;
743 } else
744 dput(alias);
745
746out:
747 mutex_unlock(lock: &MSDOS_SB(sb)->s_lock);
748 if (!inode)
749 vfat_d_version_set(dentry, version: inode_query_iversion(inode: dir));
750 return d_splice_alias(inode, dentry);
751error:
752 mutex_unlock(lock: &MSDOS_SB(sb)->s_lock);
753 return ERR_PTR(error: err);
754}
755
756static int vfat_create(struct mnt_idmap *idmap, struct inode *dir,
757 struct dentry *dentry, umode_t mode, bool excl)
758{
759 struct super_block *sb = dir->i_sb;
760 struct inode *inode;
761 struct fat_slot_info sinfo;
762 struct timespec64 ts;
763 int err;
764
765 mutex_lock(lock: &MSDOS_SB(sb)->s_lock);
766
767 ts = current_time(inode: dir);
768 err = vfat_add_entry(dir, qname: &dentry->d_name, is_dir: 0, cluster: 0, ts: &ts, sinfo: &sinfo);
769 if (err)
770 goto out;
771 inode_inc_iversion(inode: dir);
772
773 inode = fat_build_inode(sb, de: sinfo.de, i_pos: sinfo.i_pos);
774 brelse(bh: sinfo.bh);
775 if (IS_ERR(ptr: inode)) {
776 err = PTR_ERR(ptr: inode);
777 goto out;
778 }
779 inode_inc_iversion(inode);
780
781 d_instantiate(dentry, inode);
782out:
783 mutex_unlock(lock: &MSDOS_SB(sb)->s_lock);
784 return err;
785}
786
787static int vfat_rmdir(struct inode *dir, struct dentry *dentry)
788{
789 struct inode *inode = d_inode(dentry);
790 struct super_block *sb = dir->i_sb;
791 struct fat_slot_info sinfo;
792 int err;
793
794 mutex_lock(lock: &MSDOS_SB(sb)->s_lock);
795
796 err = fat_dir_empty(dir: inode);
797 if (err)
798 goto out;
799 err = vfat_find(dir, qname: &dentry->d_name, sinfo: &sinfo);
800 if (err)
801 goto out;
802
803 err = fat_remove_entries(dir, sinfo: &sinfo); /* and releases bh */
804 if (err)
805 goto out;
806 drop_nlink(inode: dir);
807
808 clear_nlink(inode);
809 fat_truncate_time(inode, NULL, flags: S_ATIME|S_MTIME);
810 fat_detach(inode);
811 vfat_d_version_set(dentry, version: inode_query_iversion(inode: dir));
812out:
813 mutex_unlock(lock: &MSDOS_SB(sb)->s_lock);
814
815 return err;
816}
817
818static int vfat_unlink(struct inode *dir, struct dentry *dentry)
819{
820 struct inode *inode = d_inode(dentry);
821 struct super_block *sb = dir->i_sb;
822 struct fat_slot_info sinfo;
823 int err;
824
825 mutex_lock(lock: &MSDOS_SB(sb)->s_lock);
826
827 err = vfat_find(dir, qname: &dentry->d_name, sinfo: &sinfo);
828 if (err)
829 goto out;
830
831 err = fat_remove_entries(dir, sinfo: &sinfo); /* and releases bh */
832 if (err)
833 goto out;
834 clear_nlink(inode);
835 fat_truncate_time(inode, NULL, flags: S_ATIME|S_MTIME);
836 fat_detach(inode);
837 vfat_d_version_set(dentry, version: inode_query_iversion(inode: dir));
838out:
839 mutex_unlock(lock: &MSDOS_SB(sb)->s_lock);
840
841 return err;
842}
843
844static struct dentry *vfat_mkdir(struct mnt_idmap *idmap, struct inode *dir,
845 struct dentry *dentry, umode_t mode)
846{
847 struct super_block *sb = dir->i_sb;
848 struct inode *inode;
849 struct fat_slot_info sinfo;
850 struct timespec64 ts;
851 int err, cluster;
852
853 mutex_lock(lock: &MSDOS_SB(sb)->s_lock);
854
855 ts = current_time(inode: dir);
856 cluster = fat_alloc_new_dir(dir, ts: &ts);
857 if (cluster < 0) {
858 err = cluster;
859 goto out;
860 }
861 err = vfat_add_entry(dir, qname: &dentry->d_name, is_dir: 1, cluster, ts: &ts, sinfo: &sinfo);
862 if (err)
863 goto out_free;
864 inode_inc_iversion(inode: dir);
865 inc_nlink(inode: dir);
866
867 inode = fat_build_inode(sb, de: sinfo.de, i_pos: sinfo.i_pos);
868 brelse(bh: sinfo.bh);
869 if (IS_ERR(ptr: inode)) {
870 err = PTR_ERR(ptr: inode);
871 /* the directory was completed, just return a error */
872 goto out;
873 }
874 inode_inc_iversion(inode);
875 set_nlink(inode, nlink: 2);
876
877 d_instantiate(dentry, inode);
878
879 mutex_unlock(lock: &MSDOS_SB(sb)->s_lock);
880 return NULL;
881
882out_free:
883 fat_free_clusters(inode: dir, cluster);
884out:
885 mutex_unlock(lock: &MSDOS_SB(sb)->s_lock);
886 return ERR_PTR(error: err);
887}
888
889static int vfat_get_dotdot_de(struct inode *inode, struct buffer_head **bh,
890 struct msdos_dir_entry **de)
891{
892 if (S_ISDIR(inode->i_mode)) {
893 if (fat_get_dotdot_entry(dir: inode, bh, de))
894 return -EIO;
895 }
896 return 0;
897}
898
899static int vfat_sync_ipos(struct inode *dir, struct inode *inode)
900{
901 if (IS_DIRSYNC(dir))
902 return fat_sync_inode(inode);
903 mark_inode_dirty(inode);
904 return 0;
905}
906
907static int vfat_update_dotdot_de(struct inode *dir, struct inode *inode,
908 struct buffer_head *dotdot_bh,
909 struct msdos_dir_entry *dotdot_de)
910{
911 fat_set_start(de: dotdot_de, cluster: MSDOS_I(inode: dir)->i_logstart);
912 mark_buffer_dirty_inode(bh: dotdot_bh, inode);
913 if (IS_DIRSYNC(dir))
914 return sync_dirty_buffer(bh: dotdot_bh);
915 return 0;
916}
917
918static void vfat_update_dir_metadata(struct inode *dir, struct timespec64 *ts)
919{
920 inode_inc_iversion(inode: dir);
921 fat_truncate_time(inode: dir, now: ts, flags: S_CTIME | S_MTIME);
922 if (IS_DIRSYNC(dir))
923 (void)fat_sync_inode(inode: dir);
924 else
925 mark_inode_dirty(inode: dir);
926}
927
928static int vfat_rename(struct inode *old_dir, struct dentry *old_dentry,
929 struct inode *new_dir, struct dentry *new_dentry)
930{
931 struct buffer_head *dotdot_bh;
932 struct msdos_dir_entry *dotdot_de = NULL;
933 struct inode *old_inode, *new_inode;
934 struct fat_slot_info old_sinfo, sinfo;
935 struct timespec64 ts;
936 loff_t new_i_pos;
937 int err, is_dir, corrupt = 0;
938 struct super_block *sb = old_dir->i_sb;
939
940 old_sinfo.bh = sinfo.bh = dotdot_bh = NULL;
941 old_inode = d_inode(dentry: old_dentry);
942 new_inode = d_inode(dentry: new_dentry);
943 mutex_lock(lock: &MSDOS_SB(sb)->s_lock);
944 err = vfat_find(dir: old_dir, qname: &old_dentry->d_name, sinfo: &old_sinfo);
945 if (err)
946 goto out;
947
948 if (old_dir != new_dir) {
949 err = vfat_get_dotdot_de(inode: old_inode, bh: &dotdot_bh, de: &dotdot_de);
950 if (err)
951 goto out;
952 }
953
954 is_dir = S_ISDIR(old_inode->i_mode);
955 ts = current_time(inode: old_dir);
956 if (new_inode) {
957 if (is_dir) {
958 err = fat_dir_empty(dir: new_inode);
959 if (err)
960 goto out;
961 }
962 new_i_pos = MSDOS_I(inode: new_inode)->i_pos;
963 fat_detach(inode: new_inode);
964 } else {
965 err = vfat_add_entry(dir: new_dir, qname: &new_dentry->d_name, is_dir, cluster: 0,
966 ts: &ts, sinfo: &sinfo);
967 if (err)
968 goto out;
969 new_i_pos = sinfo.i_pos;
970 }
971 inode_inc_iversion(inode: new_dir);
972
973 fat_detach(inode: old_inode);
974 fat_attach(inode: old_inode, i_pos: new_i_pos);
975 err = vfat_sync_ipos(dir: new_dir, inode: old_inode);
976 if (err)
977 goto error_inode;
978
979 if (dotdot_de) {
980 err = vfat_update_dotdot_de(dir: new_dir, inode: old_inode, dotdot_bh,
981 dotdot_de);
982 if (err)
983 goto error_dotdot;
984 drop_nlink(inode: old_dir);
985 if (!new_inode)
986 inc_nlink(inode: new_dir);
987 }
988
989 err = fat_remove_entries(dir: old_dir, sinfo: &old_sinfo); /* and releases bh */
990 old_sinfo.bh = NULL;
991 if (err)
992 goto error_dotdot;
993 vfat_update_dir_metadata(dir: old_dir, ts: &ts);
994
995 if (new_inode) {
996 drop_nlink(inode: new_inode);
997 if (is_dir)
998 drop_nlink(inode: new_inode);
999 fat_truncate_time(inode: new_inode, now: &ts, flags: S_CTIME);
1000 }
1001out:
1002 brelse(bh: sinfo.bh);
1003 brelse(bh: dotdot_bh);
1004 brelse(bh: old_sinfo.bh);
1005 mutex_unlock(lock: &MSDOS_SB(sb)->s_lock);
1006
1007 return err;
1008
1009error_dotdot:
1010 /* data cluster is shared, serious corruption */
1011 corrupt = 1;
1012
1013 if (dotdot_de) {
1014 corrupt |= vfat_update_dotdot_de(dir: old_dir, inode: old_inode, dotdot_bh,
1015 dotdot_de);
1016 }
1017error_inode:
1018 fat_detach(inode: old_inode);
1019 fat_attach(inode: old_inode, i_pos: old_sinfo.i_pos);
1020 if (new_inode) {
1021 fat_attach(inode: new_inode, i_pos: new_i_pos);
1022 if (corrupt)
1023 corrupt |= fat_sync_inode(inode: new_inode);
1024 } else {
1025 /*
1026 * If new entry was not sharing the data cluster, it
1027 * shouldn't be serious corruption.
1028 */
1029 int err2 = fat_remove_entries(dir: new_dir, sinfo: &sinfo);
1030 if (corrupt)
1031 corrupt |= err2;
1032 sinfo.bh = NULL;
1033 }
1034 if (corrupt < 0) {
1035 fat_fs_error(new_dir->i_sb,
1036 "%s: Filesystem corrupted (i_pos %lld)",
1037 __func__, new_i_pos);
1038 }
1039 goto out;
1040}
1041
1042static void vfat_exchange_ipos(struct inode *old_inode, struct inode *new_inode,
1043 loff_t old_i_pos, loff_t new_i_pos)
1044{
1045 fat_detach(inode: old_inode);
1046 fat_detach(inode: new_inode);
1047 fat_attach(inode: old_inode, i_pos: new_i_pos);
1048 fat_attach(inode: new_inode, i_pos: old_i_pos);
1049}
1050
1051static void vfat_move_nlink(struct inode *src, struct inode *dst)
1052{
1053 drop_nlink(inode: src);
1054 inc_nlink(inode: dst);
1055}
1056
1057static int vfat_rename_exchange(struct inode *old_dir, struct dentry *old_dentry,
1058 struct inode *new_dir, struct dentry *new_dentry)
1059{
1060 struct buffer_head *old_dotdot_bh = NULL, *new_dotdot_bh = NULL;
1061 struct msdos_dir_entry *old_dotdot_de = NULL, *new_dotdot_de = NULL;
1062 struct inode *old_inode, *new_inode;
1063 struct timespec64 ts = current_time(inode: old_dir);
1064 loff_t old_i_pos, new_i_pos;
1065 int err, corrupt = 0;
1066 struct super_block *sb = old_dir->i_sb;
1067
1068 old_inode = d_inode(dentry: old_dentry);
1069 new_inode = d_inode(dentry: new_dentry);
1070
1071 /* Acquire super block lock for the operation to be atomic */
1072 mutex_lock(lock: &MSDOS_SB(sb)->s_lock);
1073
1074 /* if directories are not the same, get ".." info to update */
1075 if (old_dir != new_dir) {
1076 err = vfat_get_dotdot_de(inode: old_inode, bh: &old_dotdot_bh,
1077 de: &old_dotdot_de);
1078 if (err)
1079 goto out;
1080
1081 err = vfat_get_dotdot_de(inode: new_inode, bh: &new_dotdot_bh,
1082 de: &new_dotdot_de);
1083 if (err)
1084 goto out;
1085 }
1086
1087 old_i_pos = MSDOS_I(inode: old_inode)->i_pos;
1088 new_i_pos = MSDOS_I(inode: new_inode)->i_pos;
1089
1090 vfat_exchange_ipos(old_inode, new_inode, old_i_pos, new_i_pos);
1091
1092 err = vfat_sync_ipos(dir: old_dir, inode: new_inode);
1093 if (err)
1094 goto error_exchange;
1095 err = vfat_sync_ipos(dir: new_dir, inode: old_inode);
1096 if (err)
1097 goto error_exchange;
1098
1099 /* update ".." directory entry info */
1100 if (old_dotdot_de) {
1101 err = vfat_update_dotdot_de(dir: new_dir, inode: old_inode, dotdot_bh: old_dotdot_bh,
1102 dotdot_de: old_dotdot_de);
1103 if (err)
1104 goto error_old_dotdot;
1105 }
1106 if (new_dotdot_de) {
1107 err = vfat_update_dotdot_de(dir: old_dir, inode: new_inode, dotdot_bh: new_dotdot_bh,
1108 dotdot_de: new_dotdot_de);
1109 if (err)
1110 goto error_new_dotdot;
1111 }
1112
1113 /* if cross directory and only one is a directory, adjust nlink */
1114 if (!old_dotdot_de != !new_dotdot_de) {
1115 if (old_dotdot_de)
1116 vfat_move_nlink(src: old_dir, dst: new_dir);
1117 else
1118 vfat_move_nlink(src: new_dir, dst: old_dir);
1119 }
1120
1121 vfat_update_dir_metadata(dir: old_dir, ts: &ts);
1122 /* if directories are not the same, update new_dir as well */
1123 if (old_dir != new_dir)
1124 vfat_update_dir_metadata(dir: new_dir, ts: &ts);
1125
1126out:
1127 brelse(bh: old_dotdot_bh);
1128 brelse(bh: new_dotdot_bh);
1129 mutex_unlock(lock: &MSDOS_SB(sb)->s_lock);
1130
1131 return err;
1132
1133error_new_dotdot:
1134 if (new_dotdot_de) {
1135 corrupt |= vfat_update_dotdot_de(dir: new_dir, inode: new_inode,
1136 dotdot_bh: new_dotdot_bh, dotdot_de: new_dotdot_de);
1137 }
1138
1139error_old_dotdot:
1140 if (old_dotdot_de) {
1141 corrupt |= vfat_update_dotdot_de(dir: old_dir, inode: old_inode,
1142 dotdot_bh: old_dotdot_bh, dotdot_de: old_dotdot_de);
1143 }
1144
1145error_exchange:
1146 vfat_exchange_ipos(old_inode, new_inode, old_i_pos: new_i_pos, new_i_pos: old_i_pos);
1147 corrupt |= vfat_sync_ipos(dir: new_dir, inode: new_inode);
1148 corrupt |= vfat_sync_ipos(dir: old_dir, inode: old_inode);
1149
1150 if (corrupt < 0) {
1151 fat_fs_error(new_dir->i_sb,
1152 "%s: Filesystem corrupted (i_pos %lld, %lld)",
1153 __func__, old_i_pos, new_i_pos);
1154 }
1155 goto out;
1156}
1157
1158static int vfat_rename2(struct mnt_idmap *idmap, struct inode *old_dir,
1159 struct dentry *old_dentry, struct inode *new_dir,
1160 struct dentry *new_dentry, unsigned int flags)
1161{
1162 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
1163 return -EINVAL;
1164
1165 if (flags & RENAME_EXCHANGE) {
1166 return vfat_rename_exchange(old_dir, old_dentry,
1167 new_dir, new_dentry);
1168 }
1169
1170 /* VFS already handled RENAME_NOREPLACE, handle it as a normal rename */
1171 return vfat_rename(old_dir, old_dentry, new_dir, new_dentry);
1172}
1173
1174static const struct inode_operations vfat_dir_inode_operations = {
1175 .create = vfat_create,
1176 .lookup = vfat_lookup,
1177 .unlink = vfat_unlink,
1178 .mkdir = vfat_mkdir,
1179 .rmdir = vfat_rmdir,
1180 .rename = vfat_rename2,
1181 .setattr = fat_setattr,
1182 .getattr = fat_getattr,
1183 .update_time = fat_update_time,
1184};
1185
1186static void setup(struct super_block *sb)
1187{
1188 MSDOS_SB(sb)->dir_ops = &vfat_dir_inode_operations;
1189 if (MSDOS_SB(sb)->options.name_check != 's')
1190 set_default_d_op(sb, &vfat_ci_dentry_ops);
1191 else
1192 set_default_d_op(sb, &vfat_dentry_ops);
1193}
1194
1195static int vfat_fill_super(struct super_block *sb, struct fs_context *fc)
1196{
1197 return fat_fill_super(sb, fc, setup);
1198}
1199
1200static int vfat_get_tree(struct fs_context *fc)
1201{
1202 return get_tree_bdev(fc, fill_super: vfat_fill_super);
1203}
1204
1205static int vfat_parse_param(struct fs_context *fc, struct fs_parameter *param)
1206{
1207 return fat_parse_param(fc, param, is_vfat: true);
1208}
1209
1210static const struct fs_context_operations vfat_context_ops = {
1211 .parse_param = vfat_parse_param,
1212 .get_tree = vfat_get_tree,
1213 .reconfigure = fat_reconfigure,
1214 .free = fat_free_fc,
1215};
1216
1217static int vfat_init_fs_context(struct fs_context *fc)
1218{
1219 int err;
1220
1221 /* Initialize with is_vfat == true */
1222 err = fat_init_fs_context(fc, is_vfat: true);
1223 if (err)
1224 return err;
1225
1226 fc->ops = &vfat_context_ops;
1227 return 0;
1228}
1229
1230static struct file_system_type vfat_fs_type = {
1231 .owner = THIS_MODULE,
1232 .name = "vfat",
1233 .kill_sb = kill_block_super,
1234 .fs_flags = FS_REQUIRES_DEV | FS_ALLOW_IDMAP,
1235 .init_fs_context = vfat_init_fs_context,
1236 .parameters = fat_param_spec,
1237};
1238MODULE_ALIAS_FS("vfat");
1239
1240static int __init init_vfat_fs(void)
1241{
1242 return register_filesystem(&vfat_fs_type);
1243}
1244
1245static void __exit exit_vfat_fs(void)
1246{
1247 unregister_filesystem(&vfat_fs_type);
1248}
1249
1250MODULE_LICENSE("GPL");
1251MODULE_DESCRIPTION("VFAT filesystem support");
1252MODULE_AUTHOR("Gordon Chaffee");
1253
1254module_init(init_vfat_fs)
1255module_exit(exit_vfat_fs)
1256