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/time.h> 11 #include <linux/buffer_head.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, const struct inode *inode, 152 struct qstr *qstr) 153 { 154 struct fat_mount_options *options = &MSDOS_SB(dentry->d_sb)->options; 155 unsigned char msdos_name[MSDOS_NAME]; 156 int error; 157 158 error = msdos_format_name(qstr->name, qstr->len, msdos_name, options); 159 if (!error) 160 qstr->hash = full_name_hash(msdos_name, MSDOS_NAME); 161 return 0; 162 } 163 164 /* 165 * Compare two msdos names. If either of the names are invalid, 166 * we fall back to doing the standard name comparison. 167 */ 168 static int msdos_cmp(const struct dentry *parent, const struct inode *pinode, 169 const struct dentry *dentry, const struct inode *inode, 170 unsigned int len, const char *str, const struct qstr *name) 171 { 172 struct fat_mount_options *options = &MSDOS_SB(parent->d_sb)->options; 173 unsigned char a_msdos_name[MSDOS_NAME], b_msdos_name[MSDOS_NAME]; 174 int error; 175 176 error = msdos_format_name(name->name, name->len, a_msdos_name, options); 177 if (error) 178 goto old_compare; 179 error = msdos_format_name(str, len, b_msdos_name, options); 180 if (error) 181 goto old_compare; 182 error = memcmp(a_msdos_name, b_msdos_name, MSDOS_NAME); 183 out: 184 return error; 185 186 old_compare: 187 error = 1; 188 if (name->len == len) 189 error = memcmp(name->name, str, len); 190 goto out; 191 } 192 193 static const struct dentry_operations msdos_dentry_operations = { 194 .d_hash = msdos_hash, 195 .d_compare = msdos_cmp, 196 }; 197 198 /* 199 * AV. Wrappers for FAT sb operations. Is it wise? 200 */ 201 202 /***** Get inode using directory and name */ 203 static struct dentry *msdos_lookup(struct inode *dir, struct dentry *dentry, 204 struct nameidata *nd) 205 { 206 struct super_block *sb = dir->i_sb; 207 struct fat_slot_info sinfo; 208 struct inode *inode; 209 int err; 210 211 lock_super(sb); 212 213 err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo); 214 if (err) { 215 if (err == -ENOENT) { 216 inode = NULL; 217 goto out; 218 } 219 goto error; 220 } 221 222 inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos); 223 brelse(sinfo.bh); 224 if (IS_ERR(inode)) { 225 err = PTR_ERR(inode); 226 goto error; 227 } 228 out: 229 unlock_super(sb); 230 return d_splice_alias(inode, dentry); 231 232 error: 233 unlock_super(sb); 234 return ERR_PTR(err); 235 } 236 237 /***** Creates a directory entry (name is already formatted). */ 238 static int msdos_add_entry(struct inode *dir, const unsigned char *name, 239 int is_dir, int is_hid, int cluster, 240 struct timespec *ts, struct fat_slot_info *sinfo) 241 { 242 struct msdos_sb_info *sbi = MSDOS_SB(dir->i_sb); 243 struct msdos_dir_entry de; 244 __le16 time, date; 245 int err; 246 247 memcpy(de.name, name, MSDOS_NAME); 248 de.attr = is_dir ? ATTR_DIR : ATTR_ARCH; 249 if (is_hid) 250 de.attr |= ATTR_HIDDEN; 251 de.lcase = 0; 252 fat_time_unix2fat(sbi, ts, &time, &date, NULL); 253 de.cdate = de.adate = 0; 254 de.ctime = 0; 255 de.ctime_cs = 0; 256 de.time = time; 257 de.date = date; 258 de.start = cpu_to_le16(cluster); 259 de.starthi = cpu_to_le16(cluster >> 16); 260 de.size = 0; 261 262 err = fat_add_entries(dir, &de, 1, sinfo); 263 if (err) 264 return err; 265 266 dir->i_ctime = dir->i_mtime = *ts; 267 if (IS_DIRSYNC(dir)) 268 (void)fat_sync_inode(dir); 269 else 270 mark_inode_dirty(dir); 271 272 return 0; 273 } 274 275 /***** Create a file */ 276 static int msdos_create(struct inode *dir, struct dentry *dentry, int mode, 277 struct nameidata *nd) 278 { 279 struct super_block *sb = dir->i_sb; 280 struct inode *inode = NULL; 281 struct fat_slot_info sinfo; 282 struct timespec ts; 283 unsigned char msdos_name[MSDOS_NAME]; 284 int err, is_hid; 285 286 lock_super(sb); 287 288 err = msdos_format_name(dentry->d_name.name, dentry->d_name.len, 289 msdos_name, &MSDOS_SB(sb)->options); 290 if (err) 291 goto out; 292 is_hid = (dentry->d_name.name[0] == '.') && (msdos_name[0] != '.'); 293 /* Have to do it due to foo vs. .foo conflicts */ 294 if (!fat_scan(dir, msdos_name, &sinfo)) { 295 brelse(sinfo.bh); 296 err = -EINVAL; 297 goto out; 298 } 299 300 ts = CURRENT_TIME_SEC; 301 err = msdos_add_entry(dir, msdos_name, 0, is_hid, 0, &ts, &sinfo); 302 if (err) 303 goto out; 304 inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos); 305 brelse(sinfo.bh); 306 if (IS_ERR(inode)) { 307 err = PTR_ERR(inode); 308 goto out; 309 } 310 inode->i_mtime = inode->i_atime = inode->i_ctime = ts; 311 /* timestamp is already written, so mark_inode_dirty() is unneeded. */ 312 313 d_instantiate(dentry, inode); 314 out: 315 unlock_super(sb); 316 if (!err) 317 err = fat_flush_inodes(sb, dir, inode); 318 return err; 319 } 320 321 /***** Remove a directory */ 322 static int msdos_rmdir(struct inode *dir, struct dentry *dentry) 323 { 324 struct super_block *sb = dir->i_sb; 325 struct inode *inode = dentry->d_inode; 326 struct fat_slot_info sinfo; 327 int err; 328 329 lock_super(sb); 330 /* 331 * Check whether the directory is not in use, then check 332 * whether it is empty. 333 */ 334 err = fat_dir_empty(inode); 335 if (err) 336 goto out; 337 err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo); 338 if (err) 339 goto out; 340 341 err = fat_remove_entries(dir, &sinfo); /* and releases bh */ 342 if (err) 343 goto out; 344 drop_nlink(dir); 345 346 clear_nlink(inode); 347 inode->i_ctime = CURRENT_TIME_SEC; 348 fat_detach(inode); 349 out: 350 unlock_super(sb); 351 if (!err) 352 err = fat_flush_inodes(sb, dir, inode); 353 354 return err; 355 } 356 357 /***** Make a directory */ 358 static int msdos_mkdir(struct inode *dir, struct dentry *dentry, int mode) 359 { 360 struct super_block *sb = dir->i_sb; 361 struct fat_slot_info sinfo; 362 struct inode *inode; 363 unsigned char msdos_name[MSDOS_NAME]; 364 struct timespec ts; 365 int err, is_hid, cluster; 366 367 lock_super(sb); 368 369 err = msdos_format_name(dentry->d_name.name, dentry->d_name.len, 370 msdos_name, &MSDOS_SB(sb)->options); 371 if (err) 372 goto out; 373 is_hid = (dentry->d_name.name[0] == '.') && (msdos_name[0] != '.'); 374 /* foo vs .foo situation */ 375 if (!fat_scan(dir, msdos_name, &sinfo)) { 376 brelse(sinfo.bh); 377 err = -EINVAL; 378 goto out; 379 } 380 381 ts = CURRENT_TIME_SEC; 382 cluster = fat_alloc_new_dir(dir, &ts); 383 if (cluster < 0) { 384 err = cluster; 385 goto out; 386 } 387 err = msdos_add_entry(dir, msdos_name, 1, is_hid, cluster, &ts, &sinfo); 388 if (err) 389 goto out_free; 390 inc_nlink(dir); 391 392 inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos); 393 brelse(sinfo.bh); 394 if (IS_ERR(inode)) { 395 err = PTR_ERR(inode); 396 /* the directory was completed, just return a error */ 397 goto out; 398 } 399 inode->i_nlink = 2; 400 inode->i_mtime = inode->i_atime = inode->i_ctime = ts; 401 /* timestamp is already written, so mark_inode_dirty() is unneeded. */ 402 403 d_instantiate(dentry, inode); 404 405 unlock_super(sb); 406 fat_flush_inodes(sb, dir, inode); 407 return 0; 408 409 out_free: 410 fat_free_clusters(dir, cluster); 411 out: 412 unlock_super(sb); 413 return err; 414 } 415 416 /***** Unlink a file */ 417 static int msdos_unlink(struct inode *dir, struct dentry *dentry) 418 { 419 struct inode *inode = dentry->d_inode; 420 struct super_block *sb= inode->i_sb; 421 struct fat_slot_info sinfo; 422 int err; 423 424 lock_super(sb); 425 err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo); 426 if (err) 427 goto out; 428 429 err = fat_remove_entries(dir, &sinfo); /* and releases bh */ 430 if (err) 431 goto out; 432 clear_nlink(inode); 433 inode->i_ctime = CURRENT_TIME_SEC; 434 fat_detach(inode); 435 out: 436 unlock_super(sb); 437 if (!err) 438 err = fat_flush_inodes(sb, dir, inode); 439 440 return err; 441 } 442 443 static int do_msdos_rename(struct inode *old_dir, unsigned char *old_name, 444 struct dentry *old_dentry, 445 struct inode *new_dir, unsigned char *new_name, 446 struct dentry *new_dentry, int is_hid) 447 { 448 struct buffer_head *dotdot_bh; 449 struct msdos_dir_entry *dotdot_de; 450 struct inode *old_inode, *new_inode; 451 struct fat_slot_info old_sinfo, sinfo; 452 struct timespec ts; 453 loff_t dotdot_i_pos, new_i_pos; 454 int err, old_attrs, is_dir, update_dotdot, corrupt = 0; 455 456 old_sinfo.bh = sinfo.bh = dotdot_bh = NULL; 457 old_inode = old_dentry->d_inode; 458 new_inode = new_dentry->d_inode; 459 460 err = fat_scan(old_dir, old_name, &old_sinfo); 461 if (err) { 462 err = -EIO; 463 goto out; 464 } 465 466 is_dir = S_ISDIR(old_inode->i_mode); 467 update_dotdot = (is_dir && old_dir != new_dir); 468 if (update_dotdot) { 469 if (fat_get_dotdot_entry(old_inode, &dotdot_bh, &dotdot_de, 470 &dotdot_i_pos) < 0) { 471 err = -EIO; 472 goto out; 473 } 474 } 475 476 old_attrs = MSDOS_I(old_inode)->i_attrs; 477 err = fat_scan(new_dir, new_name, &sinfo); 478 if (!err) { 479 if (!new_inode) { 480 /* "foo" -> ".foo" case. just change the ATTR_HIDDEN */ 481 if (sinfo.de != old_sinfo.de) { 482 err = -EINVAL; 483 goto out; 484 } 485 if (is_hid) 486 MSDOS_I(old_inode)->i_attrs |= ATTR_HIDDEN; 487 else 488 MSDOS_I(old_inode)->i_attrs &= ~ATTR_HIDDEN; 489 if (IS_DIRSYNC(old_dir)) { 490 err = fat_sync_inode(old_inode); 491 if (err) { 492 MSDOS_I(old_inode)->i_attrs = old_attrs; 493 goto out; 494 } 495 } else 496 mark_inode_dirty(old_inode); 497 498 old_dir->i_version++; 499 old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME_SEC; 500 if (IS_DIRSYNC(old_dir)) 501 (void)fat_sync_inode(old_dir); 502 else 503 mark_inode_dirty(old_dir); 504 goto out; 505 } 506 } 507 508 ts = CURRENT_TIME_SEC; 509 if (new_inode) { 510 if (err) 511 goto out; 512 if (is_dir) { 513 err = fat_dir_empty(new_inode); 514 if (err) 515 goto out; 516 } 517 new_i_pos = MSDOS_I(new_inode)->i_pos; 518 fat_detach(new_inode); 519 } else { 520 err = msdos_add_entry(new_dir, new_name, is_dir, is_hid, 0, 521 &ts, &sinfo); 522 if (err) 523 goto out; 524 new_i_pos = sinfo.i_pos; 525 } 526 new_dir->i_version++; 527 528 fat_detach(old_inode); 529 fat_attach(old_inode, new_i_pos); 530 if (is_hid) 531 MSDOS_I(old_inode)->i_attrs |= ATTR_HIDDEN; 532 else 533 MSDOS_I(old_inode)->i_attrs &= ~ATTR_HIDDEN; 534 if (IS_DIRSYNC(new_dir)) { 535 err = fat_sync_inode(old_inode); 536 if (err) 537 goto error_inode; 538 } else 539 mark_inode_dirty(old_inode); 540 541 if (update_dotdot) { 542 int start = MSDOS_I(new_dir)->i_logstart; 543 dotdot_de->start = cpu_to_le16(start); 544 dotdot_de->starthi = cpu_to_le16(start >> 16); 545 mark_buffer_dirty_inode(dotdot_bh, old_inode); 546 if (IS_DIRSYNC(new_dir)) { 547 err = sync_dirty_buffer(dotdot_bh); 548 if (err) 549 goto error_dotdot; 550 } 551 drop_nlink(old_dir); 552 if (!new_inode) 553 inc_nlink(new_dir); 554 } 555 556 err = fat_remove_entries(old_dir, &old_sinfo); /* and releases bh */ 557 old_sinfo.bh = NULL; 558 if (err) 559 goto error_dotdot; 560 old_dir->i_version++; 561 old_dir->i_ctime = old_dir->i_mtime = ts; 562 if (IS_DIRSYNC(old_dir)) 563 (void)fat_sync_inode(old_dir); 564 else 565 mark_inode_dirty(old_dir); 566 567 if (new_inode) { 568 drop_nlink(new_inode); 569 if (is_dir) 570 drop_nlink(new_inode); 571 new_inode->i_ctime = ts; 572 } 573 out: 574 brelse(sinfo.bh); 575 brelse(dotdot_bh); 576 brelse(old_sinfo.bh); 577 return err; 578 579 error_dotdot: 580 /* data cluster is shared, serious corruption */ 581 corrupt = 1; 582 583 if (update_dotdot) { 584 int start = MSDOS_I(old_dir)->i_logstart; 585 dotdot_de->start = cpu_to_le16(start); 586 dotdot_de->starthi = cpu_to_le16(start >> 16); 587 mark_buffer_dirty_inode(dotdot_bh, old_inode); 588 corrupt |= sync_dirty_buffer(dotdot_bh); 589 } 590 error_inode: 591 fat_detach(old_inode); 592 fat_attach(old_inode, old_sinfo.i_pos); 593 MSDOS_I(old_inode)->i_attrs = old_attrs; 594 if (new_inode) { 595 fat_attach(new_inode, new_i_pos); 596 if (corrupt) 597 corrupt |= fat_sync_inode(new_inode); 598 } else { 599 /* 600 * If new entry was not sharing the data cluster, it 601 * shouldn't be serious corruption. 602 */ 603 int err2 = fat_remove_entries(new_dir, &sinfo); 604 if (corrupt) 605 corrupt |= err2; 606 sinfo.bh = NULL; 607 } 608 if (corrupt < 0) { 609 fat_fs_error(new_dir->i_sb, 610 "%s: Filesystem corrupted (i_pos %lld)", 611 __func__, sinfo.i_pos); 612 } 613 goto out; 614 } 615 616 /***** Rename, a wrapper for rename_same_dir & rename_diff_dir */ 617 static int msdos_rename(struct inode *old_dir, struct dentry *old_dentry, 618 struct inode *new_dir, struct dentry *new_dentry) 619 { 620 struct super_block *sb = old_dir->i_sb; 621 unsigned char old_msdos_name[MSDOS_NAME], new_msdos_name[MSDOS_NAME]; 622 int err, is_hid; 623 624 lock_super(sb); 625 626 err = msdos_format_name(old_dentry->d_name.name, 627 old_dentry->d_name.len, old_msdos_name, 628 &MSDOS_SB(old_dir->i_sb)->options); 629 if (err) 630 goto out; 631 err = msdos_format_name(new_dentry->d_name.name, 632 new_dentry->d_name.len, new_msdos_name, 633 &MSDOS_SB(new_dir->i_sb)->options); 634 if (err) 635 goto out; 636 637 is_hid = 638 (new_dentry->d_name.name[0] == '.') && (new_msdos_name[0] != '.'); 639 640 err = do_msdos_rename(old_dir, old_msdos_name, old_dentry, 641 new_dir, new_msdos_name, new_dentry, is_hid); 642 out: 643 unlock_super(sb); 644 if (!err) 645 err = fat_flush_inodes(sb, old_dir, new_dir); 646 return err; 647 } 648 649 static const struct inode_operations msdos_dir_inode_operations = { 650 .create = msdos_create, 651 .lookup = msdos_lookup, 652 .unlink = msdos_unlink, 653 .mkdir = msdos_mkdir, 654 .rmdir = msdos_rmdir, 655 .rename = msdos_rename, 656 .setattr = fat_setattr, 657 .getattr = fat_getattr, 658 }; 659 660 static void setup(struct super_block *sb) 661 { 662 sb->s_d_op = &msdos_dentry_operations; 663 sb->s_flags |= MS_NOATIME; 664 } 665 666 static int msdos_fill_super(struct super_block *sb, void *data, int silent) 667 { 668 return fat_fill_super(sb, data, silent, &msdos_dir_inode_operations, 669 0, setup); 670 } 671 672 static struct dentry *msdos_mount(struct file_system_type *fs_type, 673 int flags, const char *dev_name, 674 void *data) 675 { 676 return mount_bdev(fs_type, flags, dev_name, data, msdos_fill_super); 677 } 678 679 static struct file_system_type msdos_fs_type = { 680 .owner = THIS_MODULE, 681 .name = "msdos", 682 .mount = msdos_mount, 683 .kill_sb = kill_block_super, 684 .fs_flags = FS_REQUIRES_DEV, 685 }; 686 687 static int __init init_msdos_fs(void) 688 { 689 return register_filesystem(&msdos_fs_type); 690 } 691 692 static void __exit exit_msdos_fs(void) 693 { 694 unregister_filesystem(&msdos_fs_type); 695 } 696 697 MODULE_LICENSE("GPL"); 698 MODULE_AUTHOR("Werner Almesberger"); 699 MODULE_DESCRIPTION("MS-DOS filesystem support"); 700 701 module_init(init_msdos_fs) 702 module_exit(exit_msdos_fs) 703