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(&dentry->d_lock);
  50	if (!inode_eq_iversion(d_inode(dentry->d_parent), vfat_d_version(dentry)))
  51		ret = 0;
  52	spin_unlock(&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(qstr->len, 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(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(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(nls_tolower(t, *name++), 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(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(name);
 163	blen = __vfat_striptail_len(len, str);
 164	if (alen == blen) {
 165		if (nls_strnicmp(t, name->name, str, 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(name);
 181	blen = __vfat_striptail_len(len, 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(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);
 240	if (err)
 241		return -ENOENT;
 242	brelse(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(*src)) {
 284		info->valid = 0;
 285		return 0;
 286	}
 287	if (vfat_replace_char(*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(nls, 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(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(*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, charbuf, sizeof(charbuf),
 384					ip, &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, charbuf, sizeof(charbuf),
 412						ip, &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_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_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_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, sizeof(buf), "%04X", i & 0xffff);
 501		memcpy(&name_res[baselen], buf, 4);
 502		if (vfat_find_form(dir, 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(name, len, UTF16_HOST_ENDIAN,
 522				(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(uc, ip + 1, 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(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, (unsigned char *)uname, &ulen, &usize,
 603			   opts->unicode_xlate, opts->utf8, sbi->nls_io);
 604	if (err)
 605		goto out_free;
 606
 607	err = vfat_is_used_badchars(uname, ulen);
 608	if (err)
 609		goto out_free;
 610
 611	err = vfat_create_shortname(dir, sbi->nls_disk, uname, ulen,
 612				    msdos_name, &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(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(ps->name0_4, uname + offset, 5);
 633		fatwchar_to16(ps->name5_10, uname + offset + 5, 6);
 634		fatwchar_to16(ps->name11_12, uname + offset + 11, 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, &date, &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(qname);
 665	if (len == 0)
 666		return -ENOENT;
 667
 668	slots = kmalloc_array(MSDOS_SLOTS, sizeof(*slots), GFP_NOFS);
 669	if (slots == NULL)
 670		return -ENOMEM;
 671
 672	err = vfat_build_slots(dir, qname->name, len, is_dir, cluster, ts,
 673			       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(dir, ts, S_CTIME|S_MTIME);
 683	if (IS_DIRSYNC(dir))
 684		(void)fat_sync_inode(dir);
 685	else
 686		mark_inode_dirty(dir);
 687cleanup:
 688	kfree(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(qname);
 696	if (len == 0)
 697		return -ENOENT;
 698	return fat_search_long(dir, qname->name, 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, &dentry->d_name, &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, sinfo.de, sinfo.i_pos);
 722	brelse(sinfo.bh);
 723	if (IS_ERR(inode)) {
 724		err = PTR_ERR(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(&MSDOS_SB(sb)->s_lock);
 745		return alias;
 746	} else
 747		dput(alias);
 748
 749out:
 750	mutex_unlock(&MSDOS_SB(sb)->s_lock);
 751	if (!inode)
 752		vfat_d_version_set(dentry, inode_query_iversion(dir));
 753	return d_splice_alias(inode, dentry);
 754error:
 755	mutex_unlock(&MSDOS_SB(sb)->s_lock);
 756	return ERR_PTR(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(dir);
 771	err = vfat_add_entry(dir, &dentry->d_name, 0, 0, &ts, &sinfo);
 772	if (err)
 773		goto out;
 774	inode_inc_iversion(dir);
 775
 776	inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
 777	brelse(sinfo.bh);
 778	if (IS_ERR(inode)) {
 779		err = PTR_ERR(inode);
 780		goto out;
 781	}
 782	inode_inc_iversion(inode);
 783
 784	d_instantiate(dentry, inode);
 785out:
 786	mutex_unlock(&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(inode);
 800	if (err)
 801		goto out;
 802	err = vfat_find(dir, &dentry->d_name, &sinfo);
 803	if (err)
 804		goto out;
 805
 806	err = fat_remove_entries(dir, &sinfo);	/* and releases bh */
 807	if (err)
 808		goto out;
 809	drop_nlink(dir);
 810
 811	clear_nlink(inode);
 812	fat_truncate_time(inode, NULL, S_ATIME|S_MTIME);
 813	fat_detach(inode);
 814	vfat_d_version_set(dentry, inode_query_iversion(dir));
 815out:
 816	mutex_unlock(&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, &dentry->d_name, &sinfo);
 831	if (err)
 832		goto out;
 833
 834	err = fat_remove_entries(dir, &sinfo);	/* and releases bh */
 835	if (err)
 836		goto out;
 837	clear_nlink(inode);
 838	fat_truncate_time(inode, NULL, S_ATIME|S_MTIME);
 839	fat_detach(inode);
 840	vfat_d_version_set(dentry, inode_query_iversion(dir));
 841out:
 842	mutex_unlock(&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(dir);
 859	cluster = fat_alloc_new_dir(dir, &ts);
 860	if (cluster < 0) {
 861		err = cluster;
 862		goto out;
 863	}
 864	err = vfat_add_entry(dir, &dentry->d_name, 1, cluster, &ts, &sinfo);
 865	if (err)
 866		goto out_free;
 867	inode_inc_iversion(dir);
 868	inc_nlink(dir);
 869
 870	inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
 871	brelse(sinfo.bh);
 872	if (IS_ERR(inode)) {
 873		err = PTR_ERR(inode);
 874		/* the directory was completed, just return a error */
 875		goto out;
 876	}
 877	inode_inc_iversion(inode);
 878	set_nlink(inode, 2);
 879
 880	d_instantiate(dentry, inode);
 881
 882	mutex_unlock(&MSDOS_SB(sb)->s_lock);
 883	return 0;
 884
 885out_free:
 886	fat_free_clusters(dir, cluster);
 887out:
 888	mutex_unlock(&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(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(dotdot_de, MSDOS_I(dir)->i_logstart);
 915	mark_buffer_dirty_inode(dotdot_bh, inode);
 916	if (IS_DIRSYNC(dir))
 917		return sync_dirty_buffer(dotdot_bh);
 918	return 0;
 919}
 920
 921static void vfat_update_dir_metadata(struct inode *dir, struct timespec64 *ts)
 922{
 923	inode_inc_iversion(dir);
 924	fat_truncate_time(dir, ts, S_CTIME | S_MTIME);
 925	if (IS_DIRSYNC(dir))
 926		(void)fat_sync_inode(dir);
 927	else
 928		mark_inode_dirty(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(old_dentry);
 945	new_inode = d_inode(new_dentry);
 946	mutex_lock(&MSDOS_SB(sb)->s_lock);
 947	err = vfat_find(old_dir, &old_dentry->d_name, &old_sinfo);
 948	if (err)
 949		goto out;
 950
 951	if (old_dir != new_dir) {
 952		err = vfat_get_dotdot_de(old_inode, &dotdot_bh, &dotdot_de);
 953		if (err)
 954			goto out;
 955	}
 956
 957	is_dir = S_ISDIR(old_inode->i_mode);
 958	ts = current_time(old_dir);
 959	if (new_inode) {
 960		if (is_dir) {
 961			err = fat_dir_empty(new_inode);
 962			if (err)
 963				goto out;
 964		}
 965		new_i_pos = MSDOS_I(new_inode)->i_pos;
 966		fat_detach(new_inode);
 967	} else {
 968		err = vfat_add_entry(new_dir, &new_dentry->d_name, is_dir, 0,
 969				     &ts, &sinfo);
 970		if (err)
 971			goto out;
 972		new_i_pos = sinfo.i_pos;
 973	}
 974	inode_inc_iversion(new_dir);
 975
 976	fat_detach(old_inode);
 977	fat_attach(old_inode, new_i_pos);
 978	err = vfat_sync_ipos(new_dir, old_inode);
 979	if (err)
 980		goto error_inode;
 981
 982	if (dotdot_de) {
 983		err = vfat_update_dotdot_de(new_dir, old_inode, dotdot_bh,
 984					    dotdot_de);
 985		if (err)
 986			goto error_dotdot;
 987		drop_nlink(old_dir);
 988		if (!new_inode)
 989 			inc_nlink(new_dir);
 990	}
 991
 992	err = fat_remove_entries(old_dir, &old_sinfo);	/* and releases bh */
 993	old_sinfo.bh = NULL;
 994	if (err)
 995		goto error_dotdot;
 996	vfat_update_dir_metadata(old_dir, &ts);
 997
 998	if (new_inode) {
 999		drop_nlink(new_inode);
1000		if (is_dir)
1001			drop_nlink(new_inode);
1002		fat_truncate_time(new_inode, &ts, S_CTIME);
1003	}
1004out:
1005	brelse(sinfo.bh);
1006	brelse(dotdot_bh);
1007	brelse(old_sinfo.bh);
1008	mutex_unlock(&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(old_dir, old_inode, dotdot_bh,
1018						 dotdot_de);
1019	}
1020error_inode:
1021	fat_detach(old_inode);
1022	fat_attach(old_inode, old_sinfo.i_pos);
1023	if (new_inode) {
1024		fat_attach(new_inode, new_i_pos);
1025		if (corrupt)
1026			corrupt |= fat_sync_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(new_dir, &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(old_inode);
1049	fat_detach(new_inode);
1050	fat_attach(old_inode, new_i_pos);
1051	fat_attach(new_inode, old_i_pos);
1052}
1053
1054static void vfat_move_nlink(struct inode *src, struct inode *dst)
1055{
1056	drop_nlink(src);
1057	inc_nlink(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(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(old_dentry);
1072	new_inode = d_inode(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(old_inode, &old_dotdot_bh,
1080					 &old_dotdot_de);
1081		if (err)
1082			goto out;
1083
1084		err = vfat_get_dotdot_de(new_inode, &new_dotdot_bh,
1085					 &new_dotdot_de);
1086		if (err)
1087			goto out;
1088	}
1089
1090	old_i_pos = MSDOS_I(old_inode)->i_pos;
1091	new_i_pos = MSDOS_I(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(old_dir, new_inode);
1096	if (err)
1097		goto error_exchange;
1098	err = vfat_sync_ipos(new_dir, 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(new_dir, old_inode, old_dotdot_bh,
1105					    old_dotdot_de);
1106		if (err)
1107			goto error_old_dotdot;
1108	}
1109	if (new_dotdot_de) {
1110		err = vfat_update_dotdot_de(old_dir, new_inode, new_dotdot_bh,
1111					    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(old_dir, new_dir);
1120		else
1121			vfat_move_nlink(new_dir, old_dir);
1122	}
1123
1124	vfat_update_dir_metadata(old_dir, &ts);
1125	/* if directories are not the same, update new_dir as well */
1126	if (old_dir != new_dir)
1127		vfat_update_dir_metadata(new_dir, &ts);
1128
1129out:
1130	brelse(old_dotdot_bh);
1131	brelse(new_dotdot_bh);
1132	mutex_unlock(&MSDOS_SB(sb)->s_lock);
1133
1134	return err;
1135
1136error_new_dotdot:
1137	if (new_dotdot_de) {
1138		corrupt |= vfat_update_dotdot_de(new_dir, new_inode,
1139						 new_dotdot_bh, new_dotdot_de);
1140	}
1141
1142error_old_dotdot:
1143	if (old_dotdot_de) {
1144		corrupt |= vfat_update_dotdot_de(old_dir, old_inode,
1145						 old_dotdot_bh, old_dotdot_de);
1146	}
1147
1148error_exchange:
1149	vfat_exchange_ipos(old_inode, new_inode, new_i_pos, old_i_pos);
1150	corrupt |= vfat_sync_ipos(new_dir, new_inode);
1151	corrupt |= vfat_sync_ipos(old_dir, 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, 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, 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)