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