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(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(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(struct dentry *dentry, struct qstr *a, struct qstr *b) 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(a->name, a->len, a_msdos_name, options); 174 if (error) 175 goto old_compare; 176 error = msdos_format_name(b->name, b->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 (a->len == b->len) 186 error = memcmp(a->name, b->name, a->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 struct nameidata *nd) 202 { 203 struct super_block *sb = dir->i_sb; 204 struct fat_slot_info sinfo; 205 struct inode *inode; 206 int err; 207 208 lock_super(sb); 209 210 err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo); 211 if (err) { 212 if (err == -ENOENT) { 213 inode = NULL; 214 goto out; 215 } 216 goto error; 217 } 218 219 inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos); 220 brelse(sinfo.bh); 221 if (IS_ERR(inode)) { 222 err = PTR_ERR(inode); 223 goto error; 224 } 225 out: 226 unlock_super(sb); 227 dentry->d_op = &msdos_dentry_operations; 228 dentry = d_splice_alias(inode, dentry); 229 if (dentry) 230 dentry->d_op = &msdos_dentry_operations; 231 return dentry; 232 233 error: 234 unlock_super(sb); 235 return ERR_PTR(err); 236 } 237 238 /***** Creates a directory entry (name is already formatted). */ 239 static int msdos_add_entry(struct inode *dir, const unsigned char *name, 240 int is_dir, int is_hid, int cluster, 241 struct timespec *ts, struct fat_slot_info *sinfo) 242 { 243 struct msdos_sb_info *sbi = MSDOS_SB(dir->i_sb); 244 struct msdos_dir_entry de; 245 __le16 time, date; 246 int err; 247 248 memcpy(de.name, name, MSDOS_NAME); 249 de.attr = is_dir ? ATTR_DIR : ATTR_ARCH; 250 if (is_hid) 251 de.attr |= ATTR_HIDDEN; 252 de.lcase = 0; 253 fat_time_unix2fat(sbi, ts, &time, &date, NULL); 254 de.cdate = de.adate = 0; 255 de.ctime = 0; 256 de.ctime_cs = 0; 257 de.time = time; 258 de.date = date; 259 de.start = cpu_to_le16(cluster); 260 de.starthi = cpu_to_le16(cluster >> 16); 261 de.size = 0; 262 263 err = fat_add_entries(dir, &de, 1, sinfo); 264 if (err) 265 return err; 266 267 dir->i_ctime = dir->i_mtime = *ts; 268 if (IS_DIRSYNC(dir)) 269 (void)fat_sync_inode(dir); 270 else 271 mark_inode_dirty(dir); 272 273 return 0; 274 } 275 276 /***** Create a file */ 277 static int msdos_create(struct inode *dir, struct dentry *dentry, int mode, 278 struct nameidata *nd) 279 { 280 struct super_block *sb = dir->i_sb; 281 struct inode *inode = NULL; 282 struct fat_slot_info sinfo; 283 struct timespec ts; 284 unsigned char msdos_name[MSDOS_NAME]; 285 int err, is_hid; 286 287 lock_super(sb); 288 289 err = msdos_format_name(dentry->d_name.name, dentry->d_name.len, 290 msdos_name, &MSDOS_SB(sb)->options); 291 if (err) 292 goto out; 293 is_hid = (dentry->d_name.name[0] == '.') && (msdos_name[0] != '.'); 294 /* Have to do it due to foo vs. .foo conflicts */ 295 if (!fat_scan(dir, msdos_name, &sinfo)) { 296 brelse(sinfo.bh); 297 err = -EINVAL; 298 goto out; 299 } 300 301 ts = CURRENT_TIME_SEC; 302 err = msdos_add_entry(dir, msdos_name, 0, is_hid, 0, &ts, &sinfo); 303 if (err) 304 goto out; 305 inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos); 306 brelse(sinfo.bh); 307 if (IS_ERR(inode)) { 308 err = PTR_ERR(inode); 309 goto out; 310 } 311 inode->i_mtime = inode->i_atime = inode->i_ctime = ts; 312 /* timestamp is already written, so mark_inode_dirty() is unneeded. */ 313 314 d_instantiate(dentry, inode); 315 out: 316 unlock_super(sb); 317 if (!err) 318 err = fat_flush_inodes(sb, dir, inode); 319 return err; 320 } 321 322 /***** Remove a directory */ 323 static int msdos_rmdir(struct inode *dir, struct dentry *dentry) 324 { 325 struct super_block *sb = dir->i_sb; 326 struct inode *inode = dentry->d_inode; 327 struct fat_slot_info sinfo; 328 int err; 329 330 lock_super(sb); 331 /* 332 * Check whether the directory is not in use, then check 333 * whether it is empty. 334 */ 335 err = fat_dir_empty(inode); 336 if (err) 337 goto out; 338 err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo); 339 if (err) 340 goto out; 341 342 err = fat_remove_entries(dir, &sinfo); /* and releases bh */ 343 if (err) 344 goto out; 345 drop_nlink(dir); 346 347 clear_nlink(inode); 348 inode->i_ctime = CURRENT_TIME_SEC; 349 fat_detach(inode); 350 out: 351 unlock_super(sb); 352 if (!err) 353 err = fat_flush_inodes(sb, dir, inode); 354 355 return err; 356 } 357 358 /***** Make a directory */ 359 static int msdos_mkdir(struct inode *dir, struct dentry *dentry, int mode) 360 { 361 struct super_block *sb = dir->i_sb; 362 struct fat_slot_info sinfo; 363 struct inode *inode; 364 unsigned char msdos_name[MSDOS_NAME]; 365 struct timespec ts; 366 int err, is_hid, cluster; 367 368 lock_super(sb); 369 370 err = msdos_format_name(dentry->d_name.name, dentry->d_name.len, 371 msdos_name, &MSDOS_SB(sb)->options); 372 if (err) 373 goto out; 374 is_hid = (dentry->d_name.name[0] == '.') && (msdos_name[0] != '.'); 375 /* foo vs .foo situation */ 376 if (!fat_scan(dir, msdos_name, &sinfo)) { 377 brelse(sinfo.bh); 378 err = -EINVAL; 379 goto out; 380 } 381 382 ts = CURRENT_TIME_SEC; 383 cluster = fat_alloc_new_dir(dir, &ts); 384 if (cluster < 0) { 385 err = cluster; 386 goto out; 387 } 388 err = msdos_add_entry(dir, msdos_name, 1, is_hid, cluster, &ts, &sinfo); 389 if (err) 390 goto out_free; 391 inc_nlink(dir); 392 393 inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos); 394 brelse(sinfo.bh); 395 if (IS_ERR(inode)) { 396 err = PTR_ERR(inode); 397 /* the directory was completed, just return a error */ 398 goto out; 399 } 400 inode->i_nlink = 2; 401 inode->i_mtime = inode->i_atime = inode->i_ctime = ts; 402 /* timestamp is already written, so mark_inode_dirty() is unneeded. */ 403 404 d_instantiate(dentry, inode); 405 406 unlock_super(sb); 407 fat_flush_inodes(sb, dir, inode); 408 return 0; 409 410 out_free: 411 fat_free_clusters(dir, cluster); 412 out: 413 unlock_super(sb); 414 return err; 415 } 416 417 /***** Unlink a file */ 418 static int msdos_unlink(struct inode *dir, struct dentry *dentry) 419 { 420 struct inode *inode = dentry->d_inode; 421 struct super_block *sb= inode->i_sb; 422 struct fat_slot_info sinfo; 423 int err; 424 425 lock_super(sb); 426 err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo); 427 if (err) 428 goto out; 429 430 err = fat_remove_entries(dir, &sinfo); /* and releases bh */ 431 if (err) 432 goto out; 433 clear_nlink(inode); 434 inode->i_ctime = CURRENT_TIME_SEC; 435 fat_detach(inode); 436 out: 437 unlock_super(sb); 438 if (!err) 439 err = fat_flush_inodes(sb, dir, inode); 440 441 return err; 442 } 443 444 static int do_msdos_rename(struct inode *old_dir, unsigned char *old_name, 445 struct dentry *old_dentry, 446 struct inode *new_dir, unsigned char *new_name, 447 struct dentry *new_dentry, int is_hid) 448 { 449 struct buffer_head *dotdot_bh; 450 struct msdos_dir_entry *dotdot_de; 451 struct inode *old_inode, *new_inode; 452 struct fat_slot_info old_sinfo, sinfo; 453 struct timespec ts; 454 loff_t dotdot_i_pos, new_i_pos; 455 int err, old_attrs, is_dir, update_dotdot, corrupt = 0; 456 457 old_sinfo.bh = sinfo.bh = dotdot_bh = NULL; 458 old_inode = old_dentry->d_inode; 459 new_inode = new_dentry->d_inode; 460 461 err = fat_scan(old_dir, old_name, &old_sinfo); 462 if (err) { 463 err = -EIO; 464 goto out; 465 } 466 467 is_dir = S_ISDIR(old_inode->i_mode); 468 update_dotdot = (is_dir && old_dir != new_dir); 469 if (update_dotdot) { 470 if (fat_get_dotdot_entry(old_inode, &dotdot_bh, &dotdot_de, 471 &dotdot_i_pos) < 0) { 472 err = -EIO; 473 goto out; 474 } 475 } 476 477 old_attrs = MSDOS_I(old_inode)->i_attrs; 478 err = fat_scan(new_dir, new_name, &sinfo); 479 if (!err) { 480 if (!new_inode) { 481 /* "foo" -> ".foo" case. just change the ATTR_HIDDEN */ 482 if (sinfo.de != old_sinfo.de) { 483 err = -EINVAL; 484 goto out; 485 } 486 if (is_hid) 487 MSDOS_I(old_inode)->i_attrs |= ATTR_HIDDEN; 488 else 489 MSDOS_I(old_inode)->i_attrs &= ~ATTR_HIDDEN; 490 if (IS_DIRSYNC(old_dir)) { 491 err = fat_sync_inode(old_inode); 492 if (err) { 493 MSDOS_I(old_inode)->i_attrs = old_attrs; 494 goto out; 495 } 496 } else 497 mark_inode_dirty(old_inode); 498 499 old_dir->i_version++; 500 old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME_SEC; 501 if (IS_DIRSYNC(old_dir)) 502 (void)fat_sync_inode(old_dir); 503 else 504 mark_inode_dirty(old_dir); 505 goto out; 506 } 507 } 508 509 ts = CURRENT_TIME_SEC; 510 if (new_inode) { 511 if (err) 512 goto out; 513 if (is_dir) { 514 err = fat_dir_empty(new_inode); 515 if (err) 516 goto out; 517 } 518 new_i_pos = MSDOS_I(new_inode)->i_pos; 519 fat_detach(new_inode); 520 } else { 521 err = msdos_add_entry(new_dir, new_name, is_dir, is_hid, 0, 522 &ts, &sinfo); 523 if (err) 524 goto out; 525 new_i_pos = sinfo.i_pos; 526 } 527 new_dir->i_version++; 528 529 fat_detach(old_inode); 530 fat_attach(old_inode, new_i_pos); 531 if (is_hid) 532 MSDOS_I(old_inode)->i_attrs |= ATTR_HIDDEN; 533 else 534 MSDOS_I(old_inode)->i_attrs &= ~ATTR_HIDDEN; 535 if (IS_DIRSYNC(new_dir)) { 536 err = fat_sync_inode(old_inode); 537 if (err) 538 goto error_inode; 539 } else 540 mark_inode_dirty(old_inode); 541 542 if (update_dotdot) { 543 int start = MSDOS_I(new_dir)->i_logstart; 544 dotdot_de->start = cpu_to_le16(start); 545 dotdot_de->starthi = cpu_to_le16(start >> 16); 546 mark_buffer_dirty_inode(dotdot_bh, old_inode); 547 if (IS_DIRSYNC(new_dir)) { 548 err = sync_dirty_buffer(dotdot_bh); 549 if (err) 550 goto error_dotdot; 551 } 552 drop_nlink(old_dir); 553 if (!new_inode) 554 inc_nlink(new_dir); 555 } 556 557 err = fat_remove_entries(old_dir, &old_sinfo); /* and releases bh */ 558 old_sinfo.bh = NULL; 559 if (err) 560 goto error_dotdot; 561 old_dir->i_version++; 562 old_dir->i_ctime = old_dir->i_mtime = ts; 563 if (IS_DIRSYNC(old_dir)) 564 (void)fat_sync_inode(old_dir); 565 else 566 mark_inode_dirty(old_dir); 567 568 if (new_inode) { 569 drop_nlink(new_inode); 570 if (is_dir) 571 drop_nlink(new_inode); 572 new_inode->i_ctime = ts; 573 } 574 out: 575 brelse(sinfo.bh); 576 brelse(dotdot_bh); 577 brelse(old_sinfo.bh); 578 return err; 579 580 error_dotdot: 581 /* data cluster is shared, serious corruption */ 582 corrupt = 1; 583 584 if (update_dotdot) { 585 int start = MSDOS_I(old_dir)->i_logstart; 586 dotdot_de->start = cpu_to_le16(start); 587 dotdot_de->starthi = cpu_to_le16(start >> 16); 588 mark_buffer_dirty_inode(dotdot_bh, old_inode); 589 corrupt |= sync_dirty_buffer(dotdot_bh); 590 } 591 error_inode: 592 fat_detach(old_inode); 593 fat_attach(old_inode, old_sinfo.i_pos); 594 MSDOS_I(old_inode)->i_attrs = old_attrs; 595 if (new_inode) { 596 fat_attach(new_inode, new_i_pos); 597 if (corrupt) 598 corrupt |= fat_sync_inode(new_inode); 599 } else { 600 /* 601 * If new entry was not sharing the data cluster, it 602 * shouldn't be serious corruption. 603 */ 604 int err2 = fat_remove_entries(new_dir, &sinfo); 605 if (corrupt) 606 corrupt |= err2; 607 sinfo.bh = NULL; 608 } 609 if (corrupt < 0) { 610 fat_fs_error(new_dir->i_sb, 611 "%s: Filesystem corrupted (i_pos %lld)", 612 __func__, sinfo.i_pos); 613 } 614 goto out; 615 } 616 617 /***** Rename, a wrapper for rename_same_dir & rename_diff_dir */ 618 static int msdos_rename(struct inode *old_dir, struct dentry *old_dentry, 619 struct inode *new_dir, struct dentry *new_dentry) 620 { 621 struct super_block *sb = old_dir->i_sb; 622 unsigned char old_msdos_name[MSDOS_NAME], new_msdos_name[MSDOS_NAME]; 623 int err, is_hid; 624 625 lock_super(sb); 626 627 err = msdos_format_name(old_dentry->d_name.name, 628 old_dentry->d_name.len, old_msdos_name, 629 &MSDOS_SB(old_dir->i_sb)->options); 630 if (err) 631 goto out; 632 err = msdos_format_name(new_dentry->d_name.name, 633 new_dentry->d_name.len, new_msdos_name, 634 &MSDOS_SB(new_dir->i_sb)->options); 635 if (err) 636 goto out; 637 638 is_hid = 639 (new_dentry->d_name.name[0] == '.') && (new_msdos_name[0] != '.'); 640 641 err = do_msdos_rename(old_dir, old_msdos_name, old_dentry, 642 new_dir, new_msdos_name, new_dentry, is_hid); 643 out: 644 unlock_super(sb); 645 if (!err) 646 err = fat_flush_inodes(sb, old_dir, new_dir); 647 return err; 648 } 649 650 static const struct inode_operations msdos_dir_inode_operations = { 651 .create = msdos_create, 652 .lookup = msdos_lookup, 653 .unlink = msdos_unlink, 654 .mkdir = msdos_mkdir, 655 .rmdir = msdos_rmdir, 656 .rename = msdos_rename, 657 .setattr = fat_setattr, 658 .getattr = fat_getattr, 659 }; 660 661 static int msdos_fill_super(struct super_block *sb, void *data, int silent) 662 { 663 int res; 664 665 res = fat_fill_super(sb, data, silent, &msdos_dir_inode_operations, 0); 666 if (res) 667 return res; 668 669 sb->s_flags |= MS_NOATIME; 670 sb->s_root->d_op = &msdos_dentry_operations; 671 return 0; 672 } 673 674 static int msdos_get_sb(struct file_system_type *fs_type, 675 int flags, const char *dev_name, 676 void *data, struct vfsmount *mnt) 677 { 678 return get_sb_bdev(fs_type, flags, dev_name, data, msdos_fill_super, 679 mnt); 680 } 681 682 static struct file_system_type msdos_fs_type = { 683 .owner = THIS_MODULE, 684 .name = "msdos", 685 .get_sb = msdos_get_sb, 686 .kill_sb = kill_block_super, 687 .fs_flags = FS_REQUIRES_DEV, 688 }; 689 690 static int __init init_msdos_fs(void) 691 { 692 return register_filesystem(&msdos_fs_type); 693 } 694 695 static void __exit exit_msdos_fs(void) 696 { 697 unregister_filesystem(&msdos_fs_type); 698 } 699 700 MODULE_LICENSE("GPL"); 701 MODULE_AUTHOR("Werner Almesberger"); 702 MODULE_DESCRIPTION("MS-DOS filesystem support"); 703 704 module_init(init_msdos_fs) 705 module_exit(exit_msdos_fs) 706