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