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/msdos_fs.h> 13#include <linux/smp_lock.h> 14 15/* Characters that are undesirable in an MS-DOS file name */ 16static unsigned char bad_chars[] = "*?<>|\""; 17static unsigned char bad_if_strict_pc[] = "+=,; "; 18/* GEMDOS is less restrictive */ 19static unsigned char bad_if_strict_atari[] = " "; 20 21#define bad_if_strict(opts) \ 22 ((opts)->atari ? bad_if_strict_atari : bad_if_strict_pc) 23 24/***** Formats an MS-DOS file name. Rejects invalid names. */ 25static int msdos_format_name(const unsigned char *name, int len, 26 unsigned char *res, struct fat_mount_options *opts) 27 /* 28 * name is the proposed name, len is its length, res is 29 * the resulting name, opts->name_check is either (r)elaxed, 30 * (n)ormal or (s)trict, opts->dotsOK allows dots at the 31 * beginning of name (for hidden files) 32 */ 33{ 34 unsigned char *walk; 35 unsigned char c; 36 int space; 37 38 if (name[0] == '.') { /* dotfile because . and .. already done */ 39 if (opts->dotsOK) { 40 /* Get rid of dot - test for it elsewhere */ 41 name++; 42 len--; 43 } else if (!opts->atari) 44 return -EINVAL; 45 } 46 /* 47 * disallow names that _really_ start with a dot for MS-DOS, 48 * GEMDOS does not care 49 */ 50 space = !opts->atari; 51 c = 0; 52 for (walk = res; len && walk - res < 8; walk++) { 53 c = *name++; 54 len--; 55 if (opts->name_check != 'r' && strchr(bad_chars, c)) 56 return -EINVAL; 57 if (opts->name_check == 's' && strchr(bad_if_strict(opts), c)) 58 return -EINVAL; 59 if (c >= 'A' && c <= 'Z' && opts->name_check == 's') 60 return -EINVAL; 61 if (c < ' ' || c == ':' || c == '\\') 62 return -EINVAL; 63 /* 64 * 0xE5 is legal as a first character, but we must substitute 65 * 0x05 because 0xE5 marks deleted files. Yes, DOS really 66 * does this. 67 * It seems that Microsoft hacked DOS to support non-US 68 * characters after the 0xE5 character was already in use to 69 * mark deleted files. 70 */ 71 if ((res == walk) && (c == 0xE5)) 72 c = 0x05; 73 if (c == '.') 74 break; 75 space = (c == ' '); 76 *walk = (!opts->nocase && c >= 'a' && c <= 'z') ? c - 32 : c; 77 } 78 if (space) 79 return -EINVAL; 80 if (opts->name_check == 's' && len && c != '.') { 81 c = *name++; 82 len--; 83 if (c != '.') 84 return -EINVAL; 85 } 86 while (c != '.' && len--) 87 c = *name++; 88 if (c == '.') { 89 while (walk - res < 8) 90 *walk++ = ' '; 91 while (len > 0 && walk - res < MSDOS_NAME) { 92 c = *name++; 93 len--; 94 if (opts->name_check != 'r' && strchr(bad_chars, c)) 95 return -EINVAL; 96 if (opts->name_check == 's' && 97 strchr(bad_if_strict(opts), c)) 98 return -EINVAL; 99 if (c < ' ' || c == ':' || c == '\\') 100 return -EINVAL; 101 if (c == '.') { 102 if (opts->name_check == 's') 103 return -EINVAL; 104 break; 105 } 106 if (c >= 'A' && c <= 'Z' && opts->name_check == 's') 107 return -EINVAL; 108 space = c == ' '; 109 if (!opts->nocase && c >= 'a' && c <= 'z') 110 *walk++ = c - 32; 111 else 112 *walk++ = c; 113 } 114 if (space) 115 return -EINVAL; 116 if (opts->name_check == 's' && len) 117 return -EINVAL; 118 } 119 while (walk - res < MSDOS_NAME) 120 *walk++ = ' '; 121 122 return 0; 123} 124 125/***** Locates a directory entry. Uses unformatted name. */ 126static int msdos_find(struct inode *dir, const unsigned char *name, int len, 127 struct fat_slot_info *sinfo) 128{ 129 struct msdos_sb_info *sbi = MSDOS_SB(dir->i_sb); 130 unsigned char msdos_name[MSDOS_NAME]; 131 int err; 132 133 err = msdos_format_name(name, len, msdos_name, &sbi->options); 134 if (err) 135 return -ENOENT; 136 137 err = fat_scan(dir, msdos_name, sinfo); 138 if (!err && sbi->options.dotsOK) { 139 if (name[0] == '.') { 140 if (!(sinfo->de->attr & ATTR_HIDDEN)) 141 err = -ENOENT; 142 } else { 143 if (sinfo->de->attr & ATTR_HIDDEN) 144 err = -ENOENT; 145 } 146 if (err) 147 brelse(sinfo->bh); 148 } 149 return err; 150} 151 152/* 153 * Compute the hash for the msdos name corresponding to the dentry. 154 * Note: if the name is invalid, we leave the hash code unchanged so 155 * that the existing dentry can be used. The msdos fs routines will 156 * return ENOENT or EINVAL as appropriate. 157 */ 158static int msdos_hash(struct dentry *dentry, struct qstr *qstr) 159{ 160 struct fat_mount_options *options = &MSDOS_SB(dentry->d_sb)->options; 161 unsigned char msdos_name[MSDOS_NAME]; 162 int error; 163 164 error = msdos_format_name(qstr->name, qstr->len, msdos_name, options); 165 if (!error) 166 qstr->hash = full_name_hash(msdos_name, MSDOS_NAME); 167 return 0; 168} 169 170/* 171 * Compare two msdos names. If either of the names are invalid, 172 * we fall back to doing the standard name comparison. 173 */ 174static int msdos_cmp(struct dentry *dentry, struct qstr *a, struct qstr *b) 175{ 176 struct fat_mount_options *options = &MSDOS_SB(dentry->d_sb)->options; 177 unsigned char a_msdos_name[MSDOS_NAME], b_msdos_name[MSDOS_NAME]; 178 int error; 179 180 error = msdos_format_name(a->name, a->len, a_msdos_name, options); 181 if (error) 182 goto old_compare; 183 error = msdos_format_name(b->name, b->len, b_msdos_name, options); 184 if (error) 185 goto old_compare; 186 error = memcmp(a_msdos_name, b_msdos_name, MSDOS_NAME); 187out: 188 return error; 189 190old_compare: 191 error = 1; 192 if (a->len == b->len) 193 error = memcmp(a->name, b->name, a->len); 194 goto out; 195} 196 197static struct dentry_operations msdos_dentry_operations = { 198 .d_hash = msdos_hash, 199 .d_compare = msdos_cmp, 200}; 201 202/* 203 * AV. Wrappers for FAT sb operations. Is it wise? 204 */ 205 206/***** Get inode using directory and name */ 207static struct dentry *msdos_lookup(struct inode *dir, struct dentry *dentry, 208 struct nameidata *nd) 209{ 210 struct super_block *sb = dir->i_sb; 211 struct fat_slot_info sinfo; 212 struct inode *inode = NULL; 213 int res; 214 215 dentry->d_op = &msdos_dentry_operations; 216 217 lock_kernel(); 218 res = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo); 219 if (res == -ENOENT) 220 goto add; 221 if (res < 0) 222 goto out; 223 inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos); 224 brelse(sinfo.bh); 225 if (IS_ERR(inode)) { 226 res = PTR_ERR(inode); 227 goto out; 228 } 229add: 230 res = 0; 231 dentry = d_splice_alias(inode, dentry); 232 if (dentry) 233 dentry->d_op = &msdos_dentry_operations; 234out: 235 unlock_kernel(); 236 if (!res) 237 return dentry; 238 return ERR_PTR(res); 239} 240 241/***** Creates a directory entry (name is already formatted). */ 242static int msdos_add_entry(struct inode *dir, const unsigned char *name, 243 int is_dir, int is_hid, int cluster, 244 struct timespec *ts, struct fat_slot_info *sinfo) 245{ 246 struct msdos_dir_entry de; 247 __le16 time, date; 248 int err; 249 250 memcpy(de.name, name, MSDOS_NAME); 251 de.attr = is_dir ? ATTR_DIR : ATTR_ARCH; 252 if (is_hid) 253 de.attr |= ATTR_HIDDEN; 254 de.lcase = 0; 255 fat_date_unix2dos(ts->tv_sec, &time, &date); 256 de.cdate = de.adate = 0; 257 de.ctime = 0; 258 de.ctime_cs = 0; 259 de.time = time; 260 de.date = date; 261 de.start = cpu_to_le16(cluster); 262 de.starthi = cpu_to_le16(cluster >> 16); 263 de.size = 0; 264 265 err = fat_add_entries(dir, &de, 1, sinfo); 266 if (err) 267 return err; 268 269 dir->i_ctime = dir->i_mtime = *ts; 270 if (IS_DIRSYNC(dir)) 271 (void)fat_sync_inode(dir); 272 else 273 mark_inode_dirty(dir); 274 275 return 0; 276} 277 278/***** Create a file */ 279static int msdos_create(struct inode *dir, struct dentry *dentry, int mode, 280 struct nameidata *nd) 281{ 282 struct super_block *sb = dir->i_sb; 283 struct inode *inode = NULL; 284 struct fat_slot_info sinfo; 285 struct timespec ts; 286 unsigned char msdos_name[MSDOS_NAME]; 287 int err, is_hid; 288 289 lock_kernel(); 290 291 err = msdos_format_name(dentry->d_name.name, dentry->d_name.len, 292 msdos_name, &MSDOS_SB(sb)->options); 293 if (err) 294 goto out; 295 is_hid = (dentry->d_name.name[0] == '.') && (msdos_name[0] != '.'); 296 /* Have to do it due to foo vs. .foo conflicts */ 297 if (!fat_scan(dir, msdos_name, &sinfo)) { 298 brelse(sinfo.bh); 299 err = -EINVAL; 300 goto out; 301 } 302 303 ts = CURRENT_TIME_SEC; 304 err = msdos_add_entry(dir, msdos_name, 0, is_hid, 0, &ts, &sinfo); 305 if (err) 306 goto out; 307 inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos); 308 brelse(sinfo.bh); 309 if (IS_ERR(inode)) { 310 err = PTR_ERR(inode); 311 goto out; 312 } 313 inode->i_mtime = inode->i_atime = inode->i_ctime = ts; 314 /* timestamp is already written, so mark_inode_dirty() is unneeded. */ 315 316 d_instantiate(dentry, inode); 317out: 318 unlock_kernel(); 319 if (!err) 320 err = fat_flush_inodes(sb, dir, inode); 321 return err; 322} 323 324/***** Remove a directory */ 325static int msdos_rmdir(struct inode *dir, struct dentry *dentry) 326{ 327 struct inode *inode = dentry->d_inode; 328 struct fat_slot_info sinfo; 329 int err; 330 331 lock_kernel(); 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); 351out: 352 unlock_kernel(); 353 if (!err) 354 err = fat_flush_inodes(inode->i_sb, dir, inode); 355 356 return err; 357} 358 359/***** Make a directory */ 360static 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_kernel(); 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_kernel(); 408 fat_flush_inodes(sb, dir, inode); 409 return 0; 410 411out_free: 412 fat_free_clusters(dir, cluster); 413out: 414 unlock_kernel(); 415 return err; 416} 417 418/***** Unlink a file */ 419static int msdos_unlink(struct inode *dir, struct dentry *dentry) 420{ 421 struct inode *inode = dentry->d_inode; 422 struct fat_slot_info sinfo; 423 int err; 424 425 lock_kernel(); 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); 436out: 437 unlock_kernel(); 438 if (!err) 439 err = fat_flush_inodes(inode->i_sb, dir, inode); 440 441 return err; 442} 443 444static 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(dotdot_bh); 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 } 574out: 575 brelse(sinfo.bh); 576 brelse(dotdot_bh); 577 brelse(old_sinfo.bh); 578 return err; 579 580error_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(dotdot_bh); 589 corrupt |= sync_dirty_buffer(dotdot_bh); 590 } 591error_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_panic(new_dir->i_sb, 611 "%s: Filesystem corrupted (i_pos %lld)", 612 __FUNCTION__, sinfo.i_pos); 613 } 614 goto out; 615} 616 617/***** Rename, a wrapper for rename_same_dir & rename_diff_dir */ 618static int msdos_rename(struct inode *old_dir, struct dentry *old_dentry, 619 struct inode *new_dir, struct dentry *new_dentry) 620{ 621 unsigned char old_msdos_name[MSDOS_NAME], new_msdos_name[MSDOS_NAME]; 622 int err, is_hid; 623 624 lock_kernel(); 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); 642out: 643 unlock_kernel(); 644 if (!err) 645 err = fat_flush_inodes(old_dir->i_sb, old_dir, new_dir); 646 return err; 647} 648 649static 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_notify_change, 657 .getattr = fat_getattr, 658}; 659 660static int msdos_fill_super(struct super_block *sb, void *data, int silent) 661{ 662 int res; 663 664 res = fat_fill_super(sb, data, silent, &msdos_dir_inode_operations, 0); 665 if (res) 666 return res; 667 668 sb->s_flags |= MS_NOATIME; 669 sb->s_root->d_op = &msdos_dentry_operations; 670 return 0; 671} 672 673static int msdos_get_sb(struct file_system_type *fs_type, 674 int flags, const char *dev_name, 675 void *data, struct vfsmount *mnt) 676{ 677 return get_sb_bdev(fs_type, flags, dev_name, data, msdos_fill_super, 678 mnt); 679} 680 681static struct file_system_type msdos_fs_type = { 682 .owner = THIS_MODULE, 683 .name = "msdos", 684 .get_sb = msdos_get_sb, 685 .kill_sb = kill_block_super, 686 .fs_flags = FS_REQUIRES_DEV, 687}; 688 689static int __init init_msdos_fs(void) 690{ 691 return register_filesystem(&msdos_fs_type); 692} 693 694static void __exit exit_msdos_fs(void) 695{ 696 unregister_filesystem(&msdos_fs_type); 697} 698 699MODULE_LICENSE("GPL"); 700MODULE_AUTHOR("Werner Almesberger"); 701MODULE_DESCRIPTION("MS-DOS filesystem support"); 702 703module_init(init_msdos_fs) 704module_exit(exit_msdos_fs) 705