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

source code of linux/fs/fat/namei_vfat.c