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 <linux/smp_lock.h> 13 #include "fat.h" 14 15 /* Characters that are undesirable in an MS-DOS file name */ 16 static unsigned char bad_chars[] = "*?<>|\""; 17 static unsigned char bad_if_strict[] = "+=,; "; 18 19 /***** Formats an MS-DOS file name. Rejects invalid names. */ 20 static int msdos_format_name(const unsigned char *name, int len, 21 unsigned char *res, struct fat_mount_options *opts) 22 /* 23 * name is the proposed name, len is its length, res is 24 * the resulting name, opts->name_check is either (r)elaxed, 25 * (n)ormal or (s)trict, opts->dotsOK allows dots at the 26 * beginning of name (for hidden files) 27 */ 28 { 29 unsigned char *walk; 30 unsigned char c; 31 int space; 32 33 if (name[0] == '.') { /* dotfile because . and .. already done */ 34 if (opts->dotsOK) { 35 /* Get rid of dot - test for it elsewhere */ 36 name++; 37 len--; 38 } else 39 return -EINVAL; 40 } 41 /* 42 * disallow names that _really_ start with a dot 43 */ 44 space = 1; 45 c = 0; 46 for (walk = res; len && walk - res < 8; walk++) { 47 c = *name++; 48 len--; 49 if (opts->name_check != 'r' && strchr(bad_chars, c)) 50 return -EINVAL; 51 if (opts->name_check == 's' && strchr(bad_if_strict, c)) 52 return -EINVAL; 53 if (c >= 'A' && c <= 'Z' && opts->name_check == 's') 54 return -EINVAL; 55 if (c < ' ' || c == ':' || c == '\\') 56 return -EINVAL; 57 /* 58 * 0xE5 is legal as a first character, but we must substitute 59 * 0x05 because 0xE5 marks deleted files. Yes, DOS really 60 * does this. 61 * It seems that Microsoft hacked DOS to support non-US 62 * characters after the 0xE5 character was already in use to 63 * mark deleted files. 64 */ 65 if ((res == walk) && (c == 0xE5)) 66 c = 0x05; 67 if (c == '.') 68 break; 69 space = (c == ' '); 70 *walk = (!opts->nocase && c >= 'a' && c <= 'z') ? c - 32 : c; 71 } 72 if (space) 73 return -EINVAL; 74 if (opts->name_check == 's' && len && c != '.') { 75 c = *name++; 76 len--; 77 if (c != '.') 78 return -EINVAL; 79 } 80 while (c != '.' && len--) 81 c = *name++; 82 if (c == '.') { 83 while (walk - res < 8) 84 *walk++ = ' '; 85 while (len > 0 && walk - res < MSDOS_NAME) { 86 c = *name++; 87 len--; 88 if (opts->name_check != 'r' && strchr(bad_chars, c)) 89 return -EINVAL; 90 if (opts->name_check == 's' && 91 strchr(bad_if_strict, c)) 92 return -EINVAL; 93 if (c < ' ' || c == ':' || c == '\\') 94 return -EINVAL; 95 if (c == '.') { 96 if (opts->name_check == 's') 97 return -EINVAL; 98 break; 99 } 100 if (c >= 'A' && c <= 'Z' && opts->name_check == 's') 101 return -EINVAL; 102 space = c == ' '; 103 if (!opts->nocase && c >= 'a' && c <= 'z') 104 *walk++ = c - 32; 105 else 106 *walk++ = c; 107 } 108 if (space) 109 return -EINVAL; 110 if (opts->name_check == 's' && len) 111 return -EINVAL; 112 } 113 while (walk - res < MSDOS_NAME) 114 *walk++ = ' '; 115 116 return 0; 117 } 118 119 /***** Locates a directory entry. Uses unformatted name. */ 120 static int msdos_find(struct inode *dir, const unsigned char *name, int len, 121 struct fat_slot_info *sinfo) 122 { 123 struct msdos_sb_info *sbi = MSDOS_SB(dir->i_sb); 124 unsigned char msdos_name[MSDOS_NAME]; 125 int err; 126 127 err = msdos_format_name(name, len, msdos_name, &sbi->options); 128 if (err) 129 return -ENOENT; 130 131 err = fat_scan(dir, msdos_name, sinfo); 132 if (!err && sbi->options.dotsOK) { 133 if (name[0] == '.') { 134 if (!(sinfo->de->attr & ATTR_HIDDEN)) 135 err = -ENOENT; 136 } else { 137 if (sinfo->de->attr & ATTR_HIDDEN) 138 err = -ENOENT; 139 } 140 if (err) 141 brelse(sinfo->bh); 142 } 143 return err; 144 } 145 146 /* 147 * Compute the hash for the msdos name corresponding to the dentry. 148 * Note: if the name is invalid, we leave the hash code unchanged so 149 * that the existing dentry can be used. The msdos fs routines will 150 * return ENOENT or EINVAL as appropriate. 151 */ 152 static int msdos_hash(struct dentry *dentry, 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(struct dentry *dentry, struct qstr *a, struct qstr *b) 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(a->name, a->len, a_msdos_name, options); 175 if (error) 176 goto old_compare; 177 error = msdos_format_name(b->name, b->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 (a->len == b->len) 187 error = memcmp(a->name, b->name, a->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 struct nameidata *nd) 203 { 204 struct super_block *sb = dir->i_sb; 205 struct fat_slot_info sinfo; 206 struct inode *inode; 207 int err; 208 209 lock_super(sb); 210 211 err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo); 212 if (err) { 213 if (err == -ENOENT) { 214 inode = NULL; 215 goto out; 216 } 217 goto error; 218 } 219 220 inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos); 221 brelse(sinfo.bh); 222 if (IS_ERR(inode)) { 223 err = PTR_ERR(inode); 224 goto error; 225 } 226 out: 227 unlock_super(sb); 228 dentry->d_op = &msdos_dentry_operations; 229 dentry = d_splice_alias(inode, dentry); 230 if (dentry) 231 dentry->d_op = &msdos_dentry_operations; 232 return dentry; 233 234 error: 235 unlock_super(sb); 236 return ERR_PTR(err); 237 } 238 239 /***** Creates a directory entry (name is already formatted). */ 240 static int msdos_add_entry(struct inode *dir, const unsigned char *name, 241 int is_dir, int is_hid, int cluster, 242 struct timespec *ts, struct fat_slot_info *sinfo) 243 { 244 struct msdos_sb_info *sbi = MSDOS_SB(dir->i_sb); 245 struct msdos_dir_entry de; 246 __le16 time, date; 247 int err; 248 249 memcpy(de.name, name, MSDOS_NAME); 250 de.attr = is_dir ? ATTR_DIR : ATTR_ARCH; 251 if (is_hid) 252 de.attr |= ATTR_HIDDEN; 253 de.lcase = 0; 254 fat_time_unix2fat(sbi, ts, &time, &date, NULL); 255 de.cdate = de.adate = 0; 256 de.ctime = 0; 257 de.ctime_cs = 0; 258 de.time = time; 259 de.date = date; 260 de.start = cpu_to_le16(cluster); 261 de.starthi = cpu_to_le16(cluster >> 16); 262 de.size = 0; 263 264 err = fat_add_entries(dir, &de, 1, sinfo); 265 if (err) 266 return err; 267 268 dir->i_ctime = dir->i_mtime = *ts; 269 if (IS_DIRSYNC(dir)) 270 (void)fat_sync_inode(dir); 271 else 272 mark_inode_dirty(dir); 273 274 return 0; 275 } 276 277 /***** Create a file */ 278 static int msdos_create(struct inode *dir, struct dentry *dentry, int mode, 279 struct nameidata *nd) 280 { 281 struct super_block *sb = dir->i_sb; 282 struct inode *inode = NULL; 283 struct fat_slot_info sinfo; 284 struct timespec ts; 285 unsigned char msdos_name[MSDOS_NAME]; 286 int err, is_hid; 287 288 lock_super(sb); 289 290 err = msdos_format_name(dentry->d_name.name, dentry->d_name.len, 291 msdos_name, &MSDOS_SB(sb)->options); 292 if (err) 293 goto out; 294 is_hid = (dentry->d_name.name[0] == '.') && (msdos_name[0] != '.'); 295 /* Have to do it due to foo vs. .foo conflicts */ 296 if (!fat_scan(dir, msdos_name, &sinfo)) { 297 brelse(sinfo.bh); 298 err = -EINVAL; 299 goto out; 300 } 301 302 ts = CURRENT_TIME_SEC; 303 err = msdos_add_entry(dir, msdos_name, 0, is_hid, 0, &ts, &sinfo); 304 if (err) 305 goto out; 306 inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos); 307 brelse(sinfo.bh); 308 if (IS_ERR(inode)) { 309 err = PTR_ERR(inode); 310 goto out; 311 } 312 inode->i_mtime = inode->i_atime = inode->i_ctime = ts; 313 /* timestamp is already written, so mark_inode_dirty() is unneeded. */ 314 315 d_instantiate(dentry, inode); 316 out: 317 unlock_super(sb); 318 if (!err) 319 err = fat_flush_inodes(sb, dir, inode); 320 return err; 321 } 322 323 /***** Remove a directory */ 324 static int msdos_rmdir(struct inode *dir, struct dentry *dentry) 325 { 326 struct super_block *sb = dir->i_sb; 327 struct inode *inode = dentry->d_inode; 328 struct fat_slot_info sinfo; 329 int err; 330 331 lock_super(sb); 332 /* 333 * Check whether the directory is not in use, then check 334 * whether it is empty. 335 */ 336 err = fat_dir_empty(inode); 337 if (err) 338 goto out; 339 err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo); 340 if (err) 341 goto out; 342 343 err = fat_remove_entries(dir, &sinfo); /* and releases bh */ 344 if (err) 345 goto out; 346 drop_nlink(dir); 347 348 clear_nlink(inode); 349 inode->i_ctime = CURRENT_TIME_SEC; 350 fat_detach(inode); 351 out: 352 unlock_super(sb); 353 if (!err) 354 err = fat_flush_inodes(sb, dir, inode); 355 356 return err; 357 } 358 359 /***** Make a directory */ 360 static int msdos_mkdir(struct inode *dir, struct dentry *dentry, int mode) 361 { 362 struct super_block *sb = dir->i_sb; 363 struct fat_slot_info sinfo; 364 struct inode *inode; 365 unsigned char msdos_name[MSDOS_NAME]; 366 struct timespec ts; 367 int err, is_hid, cluster; 368 369 lock_super(sb); 370 371 err = msdos_format_name(dentry->d_name.name, dentry->d_name.len, 372 msdos_name, &MSDOS_SB(sb)->options); 373 if (err) 374 goto out; 375 is_hid = (dentry->d_name.name[0] == '.') && (msdos_name[0] != '.'); 376 /* foo vs .foo situation */ 377 if (!fat_scan(dir, msdos_name, &sinfo)) { 378 brelse(sinfo.bh); 379 err = -EINVAL; 380 goto out; 381 } 382 383 ts = CURRENT_TIME_SEC; 384 cluster = fat_alloc_new_dir(dir, &ts); 385 if (cluster < 0) { 386 err = cluster; 387 goto out; 388 } 389 err = msdos_add_entry(dir, msdos_name, 1, is_hid, cluster, &ts, &sinfo); 390 if (err) 391 goto out_free; 392 inc_nlink(dir); 393 394 inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos); 395 brelse(sinfo.bh); 396 if (IS_ERR(inode)) { 397 err = PTR_ERR(inode); 398 /* the directory was completed, just return a error */ 399 goto out; 400 } 401 inode->i_nlink = 2; 402 inode->i_mtime = inode->i_atime = inode->i_ctime = ts; 403 /* timestamp is already written, so mark_inode_dirty() is unneeded. */ 404 405 d_instantiate(dentry, inode); 406 407 unlock_super(sb); 408 fat_flush_inodes(sb, dir, inode); 409 return 0; 410 411 out_free: 412 fat_free_clusters(dir, cluster); 413 out: 414 unlock_super(sb); 415 return err; 416 } 417 418 /***** Unlink a file */ 419 static int msdos_unlink(struct inode *dir, struct dentry *dentry) 420 { 421 struct inode *inode = dentry->d_inode; 422 struct super_block *sb= inode->i_sb; 423 struct fat_slot_info sinfo; 424 int err; 425 426 lock_super(sb); 427 err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo); 428 if (err) 429 goto out; 430 431 err = fat_remove_entries(dir, &sinfo); /* and releases bh */ 432 if (err) 433 goto out; 434 clear_nlink(inode); 435 inode->i_ctime = CURRENT_TIME_SEC; 436 fat_detach(inode); 437 out: 438 unlock_super(sb); 439 if (!err) 440 err = fat_flush_inodes(sb, dir, inode); 441 442 return err; 443 } 444 445 static int do_msdos_rename(struct inode *old_dir, unsigned char *old_name, 446 struct dentry *old_dentry, 447 struct inode *new_dir, unsigned char *new_name, 448 struct dentry *new_dentry, int is_hid) 449 { 450 struct buffer_head *dotdot_bh; 451 struct msdos_dir_entry *dotdot_de; 452 struct inode *old_inode, *new_inode; 453 struct fat_slot_info old_sinfo, sinfo; 454 struct timespec ts; 455 loff_t dotdot_i_pos, new_i_pos; 456 int err, old_attrs, is_dir, update_dotdot, corrupt = 0; 457 458 old_sinfo.bh = sinfo.bh = dotdot_bh = NULL; 459 old_inode = old_dentry->d_inode; 460 new_inode = new_dentry->d_inode; 461 462 err = fat_scan(old_dir, old_name, &old_sinfo); 463 if (err) { 464 err = -EIO; 465 goto out; 466 } 467 468 is_dir = S_ISDIR(old_inode->i_mode); 469 update_dotdot = (is_dir && old_dir != new_dir); 470 if (update_dotdot) { 471 if (fat_get_dotdot_entry(old_inode, &dotdot_bh, &dotdot_de, 472 &dotdot_i_pos) < 0) { 473 err = -EIO; 474 goto out; 475 } 476 } 477 478 old_attrs = MSDOS_I(old_inode)->i_attrs; 479 err = fat_scan(new_dir, new_name, &sinfo); 480 if (!err) { 481 if (!new_inode) { 482 /* "foo" -> ".foo" case. just change the ATTR_HIDDEN */ 483 if (sinfo.de != old_sinfo.de) { 484 err = -EINVAL; 485 goto out; 486 } 487 if (is_hid) 488 MSDOS_I(old_inode)->i_attrs |= ATTR_HIDDEN; 489 else 490 MSDOS_I(old_inode)->i_attrs &= ~ATTR_HIDDEN; 491 if (IS_DIRSYNC(old_dir)) { 492 err = fat_sync_inode(old_inode); 493 if (err) { 494 MSDOS_I(old_inode)->i_attrs = old_attrs; 495 goto out; 496 } 497 } else 498 mark_inode_dirty(old_inode); 499 500 old_dir->i_version++; 501 old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME_SEC; 502 if (IS_DIRSYNC(old_dir)) 503 (void)fat_sync_inode(old_dir); 504 else 505 mark_inode_dirty(old_dir); 506 goto out; 507 } 508 } 509 510 ts = CURRENT_TIME_SEC; 511 if (new_inode) { 512 if (err) 513 goto out; 514 if (is_dir) { 515 err = fat_dir_empty(new_inode); 516 if (err) 517 goto out; 518 } 519 new_i_pos = MSDOS_I(new_inode)->i_pos; 520 fat_detach(new_inode); 521 } else { 522 err = msdos_add_entry(new_dir, new_name, is_dir, is_hid, 0, 523 &ts, &sinfo); 524 if (err) 525 goto out; 526 new_i_pos = sinfo.i_pos; 527 } 528 new_dir->i_version++; 529 530 fat_detach(old_inode); 531 fat_attach(old_inode, new_i_pos); 532 if (is_hid) 533 MSDOS_I(old_inode)->i_attrs |= ATTR_HIDDEN; 534 else 535 MSDOS_I(old_inode)->i_attrs &= ~ATTR_HIDDEN; 536 if (IS_DIRSYNC(new_dir)) { 537 err = fat_sync_inode(old_inode); 538 if (err) 539 goto error_inode; 540 } else 541 mark_inode_dirty(old_inode); 542 543 if (update_dotdot) { 544 int start = MSDOS_I(new_dir)->i_logstart; 545 dotdot_de->start = cpu_to_le16(start); 546 dotdot_de->starthi = cpu_to_le16(start >> 16); 547 mark_buffer_dirty(dotdot_bh); 548 if (IS_DIRSYNC(new_dir)) { 549 err = sync_dirty_buffer(dotdot_bh); 550 if (err) 551 goto error_dotdot; 552 } 553 drop_nlink(old_dir); 554 if (!new_inode) 555 inc_nlink(new_dir); 556 } 557 558 err = fat_remove_entries(old_dir, &old_sinfo); /* and releases bh */ 559 old_sinfo.bh = NULL; 560 if (err) 561 goto error_dotdot; 562 old_dir->i_version++; 563 old_dir->i_ctime = old_dir->i_mtime = ts; 564 if (IS_DIRSYNC(old_dir)) 565 (void)fat_sync_inode(old_dir); 566 else 567 mark_inode_dirty(old_dir); 568 569 if (new_inode) { 570 drop_nlink(new_inode); 571 if (is_dir) 572 drop_nlink(new_inode); 573 new_inode->i_ctime = ts; 574 } 575 out: 576 brelse(sinfo.bh); 577 brelse(dotdot_bh); 578 brelse(old_sinfo.bh); 579 return err; 580 581 error_dotdot: 582 /* data cluster is shared, serious corruption */ 583 corrupt = 1; 584 585 if (update_dotdot) { 586 int start = MSDOS_I(old_dir)->i_logstart; 587 dotdot_de->start = cpu_to_le16(start); 588 dotdot_de->starthi = cpu_to_le16(start >> 16); 589 mark_buffer_dirty(dotdot_bh); 590 corrupt |= sync_dirty_buffer(dotdot_bh); 591 } 592 error_inode: 593 fat_detach(old_inode); 594 fat_attach(old_inode, old_sinfo.i_pos); 595 MSDOS_I(old_inode)->i_attrs = old_attrs; 596 if (new_inode) { 597 fat_attach(new_inode, new_i_pos); 598 if (corrupt) 599 corrupt |= fat_sync_inode(new_inode); 600 } else { 601 /* 602 * If new entry was not sharing the data cluster, it 603 * shouldn't be serious corruption. 604 */ 605 int err2 = fat_remove_entries(new_dir, &sinfo); 606 if (corrupt) 607 corrupt |= err2; 608 sinfo.bh = NULL; 609 } 610 if (corrupt < 0) { 611 fat_fs_panic(new_dir->i_sb, 612 "%s: Filesystem corrupted (i_pos %lld)", 613 __func__, sinfo.i_pos); 614 } 615 goto out; 616 } 617 618 /***** Rename, a wrapper for rename_same_dir & rename_diff_dir */ 619 static int msdos_rename(struct inode *old_dir, struct dentry *old_dentry, 620 struct inode *new_dir, struct dentry *new_dentry) 621 { 622 struct super_block *sb = old_dir->i_sb; 623 unsigned char old_msdos_name[MSDOS_NAME], new_msdos_name[MSDOS_NAME]; 624 int err, is_hid; 625 626 lock_super(sb); 627 628 err = msdos_format_name(old_dentry->d_name.name, 629 old_dentry->d_name.len, old_msdos_name, 630 &MSDOS_SB(old_dir->i_sb)->options); 631 if (err) 632 goto out; 633 err = msdos_format_name(new_dentry->d_name.name, 634 new_dentry->d_name.len, new_msdos_name, 635 &MSDOS_SB(new_dir->i_sb)->options); 636 if (err) 637 goto out; 638 639 is_hid = 640 (new_dentry->d_name.name[0] == '.') && (new_msdos_name[0] != '.'); 641 642 err = do_msdos_rename(old_dir, old_msdos_name, old_dentry, 643 new_dir, new_msdos_name, new_dentry, is_hid); 644 out: 645 unlock_super(sb); 646 if (!err) 647 err = fat_flush_inodes(sb, old_dir, new_dir); 648 return err; 649 } 650 651 static const struct inode_operations msdos_dir_inode_operations = { 652 .create = msdos_create, 653 .lookup = msdos_lookup, 654 .unlink = msdos_unlink, 655 .mkdir = msdos_mkdir, 656 .rmdir = msdos_rmdir, 657 .rename = msdos_rename, 658 .setattr = fat_setattr, 659 .getattr = fat_getattr, 660 }; 661 662 static int msdos_fill_super(struct super_block *sb, void *data, int silent) 663 { 664 int res; 665 666 res = fat_fill_super(sb, data, silent, &msdos_dir_inode_operations, 0); 667 if (res) 668 return res; 669 670 sb->s_flags |= MS_NOATIME; 671 sb->s_root->d_op = &msdos_dentry_operations; 672 return 0; 673 } 674 675 static int msdos_get_sb(struct file_system_type *fs_type, 676 int flags, const char *dev_name, 677 void *data, struct vfsmount *mnt) 678 { 679 return get_sb_bdev(fs_type, flags, dev_name, data, msdos_fill_super, 680 mnt); 681 } 682 683 static struct file_system_type msdos_fs_type = { 684 .owner = THIS_MODULE, 685 .name = "msdos", 686 .get_sb = msdos_get_sb, 687 .kill_sb = kill_block_super, 688 .fs_flags = FS_REQUIRES_DEV, 689 }; 690 691 static int __init init_msdos_fs(void) 692 { 693 return register_filesystem(&msdos_fs_type); 694 } 695 696 static void __exit exit_msdos_fs(void) 697 { 698 unregister_filesystem(&msdos_fs_type); 699 } 700 701 MODULE_LICENSE("GPL"); 702 MODULE_AUTHOR("Werner Almesberger"); 703 MODULE_DESCRIPTION("MS-DOS filesystem support"); 704 705 module_init(init_msdos_fs) 706 module_exit(exit_msdos_fs) 707