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