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/iversion.h> 11 #include "fat.h" 12 13 /* Characters that are undesirable in an MS-DOS file name */ 14 static unsigned char bad_chars[] = "*?<>|\""; 15 static unsigned char bad_if_strict[] = "+=,; "; 16 17 /***** Formats an MS-DOS file name. Rejects invalid names. */ 18 static int msdos_format_name(const unsigned char *name, int len, 19 unsigned char *res, struct fat_mount_options *opts) 20 /* 21 * name is the proposed name, len is its length, res is 22 * the resulting name, opts->name_check is either (r)elaxed, 23 * (n)ormal or (s)trict, opts->dotsOK allows dots at the 24 * beginning of name (for hidden files) 25 */ 26 { 27 unsigned char *walk; 28 unsigned char c; 29 int space; 30 31 if (name[0] == '.') { /* dotfile because . and .. already done */ 32 if (opts->dotsOK) { 33 /* Get rid of dot - test for it elsewhere */ 34 name++; 35 len--; 36 } else 37 return -EINVAL; 38 } 39 /* 40 * disallow names that _really_ start with a dot 41 */ 42 space = 1; 43 c = 0; 44 for (walk = res; len && walk - res < 8; walk++) { 45 c = *name++; 46 len--; 47 if (opts->name_check != 'r' && strchr(bad_chars, c)) 48 return -EINVAL; 49 if (opts->name_check == 's' && strchr(bad_if_strict, c)) 50 return -EINVAL; 51 if (c >= 'A' && c <= 'Z' && opts->name_check == 's') 52 return -EINVAL; 53 if (c < ' ' || c == ':' || c == '\\') 54 return -EINVAL; 55 /* 56 * 0xE5 is legal as a first character, but we must substitute 57 * 0x05 because 0xE5 marks deleted files. Yes, DOS really 58 * does this. 59 * It seems that Microsoft hacked DOS to support non-US 60 * characters after the 0xE5 character was already in use to 61 * mark deleted files. 62 */ 63 if ((res == walk) && (c == 0xE5)) 64 c = 0x05; 65 if (c == '.') 66 break; 67 space = (c == ' '); 68 *walk = (!opts->nocase && c >= 'a' && c <= 'z') ? c - 32 : c; 69 } 70 if (space) 71 return -EINVAL; 72 if (opts->name_check == 's' && len && c != '.') { 73 c = *name++; 74 len--; 75 if (c != '.') 76 return -EINVAL; 77 } 78 while (c != '.' && len--) 79 c = *name++; 80 if (c == '.') { 81 while (walk - res < 8) 82 *walk++ = ' '; 83 while (len > 0 && walk - res < MSDOS_NAME) { 84 c = *name++; 85 len--; 86 if (opts->name_check != 'r' && strchr(bad_chars, c)) 87 return -EINVAL; 88 if (opts->name_check == 's' && 89 strchr(bad_if_strict, c)) 90 return -EINVAL; 91 if (c < ' ' || c == ':' || c == '\\') 92 return -EINVAL; 93 if (c == '.') { 94 if (opts->name_check == 's') 95 return -EINVAL; 96 break; 97 } 98 if (c >= 'A' && c <= 'Z' && opts->name_check == 's') 99 return -EINVAL; 100 space = c == ' '; 101 if (!opts->nocase && c >= 'a' && c <= 'z') 102 *walk++ = c - 32; 103 else 104 *walk++ = c; 105 } 106 if (space) 107 return -EINVAL; 108 if (opts->name_check == 's' && len) 109 return -EINVAL; 110 } 111 while (walk - res < MSDOS_NAME) 112 *walk++ = ' '; 113 114 return 0; 115 } 116 117 /***** Locates a directory entry. Uses unformatted name. */ 118 static int msdos_find(struct inode *dir, const unsigned char *name, int len, 119 struct fat_slot_info *sinfo) 120 { 121 struct msdos_sb_info *sbi = MSDOS_SB(dir->i_sb); 122 unsigned char msdos_name[MSDOS_NAME]; 123 int err; 124 125 err = msdos_format_name(name, len, msdos_name, &sbi->options); 126 if (err) 127 return -ENOENT; 128 129 err = fat_scan(dir, msdos_name, sinfo); 130 if (!err && sbi->options.dotsOK) { 131 if (name[0] == '.') { 132 if (!(sinfo->de->attr & ATTR_HIDDEN)) 133 err = -ENOENT; 134 } else { 135 if (sinfo->de->attr & ATTR_HIDDEN) 136 err = -ENOENT; 137 } 138 if (err) 139 brelse(sinfo->bh); 140 } 141 return err; 142 } 143 144 /* 145 * Compute the hash for the msdos name corresponding to the dentry. 146 * Note: if the name is invalid, we leave the hash code unchanged so 147 * that the existing dentry can be used. The msdos fs routines will 148 * return ENOENT or EINVAL as appropriate. 149 */ 150 static int msdos_hash(const struct dentry *dentry, struct qstr *qstr) 151 { 152 struct fat_mount_options *options = &MSDOS_SB(dentry->d_sb)->options; 153 unsigned char msdos_name[MSDOS_NAME]; 154 int error; 155 156 error = msdos_format_name(qstr->name, qstr->len, msdos_name, options); 157 if (!error) 158 qstr->hash = full_name_hash(dentry, msdos_name, MSDOS_NAME); 159 return 0; 160 } 161 162 /* 163 * Compare two msdos names. If either of the names are invalid, 164 * we fall back to doing the standard name comparison. 165 */ 166 static int msdos_cmp(const struct dentry *dentry, 167 unsigned int len, const char *str, const struct qstr *name) 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(name->name, name->len, a_msdos_name, options); 174 if (error) 175 goto old_compare; 176 error = msdos_format_name(str, 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 (name->len == len) 186 error = memcmp(name->name, str, 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 unsigned int flags) 202 { 203 struct super_block *sb = dir->i_sb; 204 struct fat_slot_info sinfo; 205 struct inode *inode; 206 int err; 207 208 mutex_lock(&MSDOS_SB(sb)->s_lock); 209 err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo); 210 switch (err) { 211 case -ENOENT: 212 inode = NULL; 213 break; 214 case 0: 215 inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos); 216 brelse(sinfo.bh); 217 break; 218 default: 219 inode = ERR_PTR(err); 220 } 221 mutex_unlock(&MSDOS_SB(sb)->s_lock); 222 return d_splice_alias(inode, dentry); 223 } 224 225 /***** Creates a directory entry (name is already formatted). */ 226 static int msdos_add_entry(struct inode *dir, const unsigned char *name, 227 int is_dir, int is_hid, int cluster, 228 struct timespec *ts, struct fat_slot_info *sinfo) 229 { 230 struct msdos_sb_info *sbi = MSDOS_SB(dir->i_sb); 231 struct msdos_dir_entry de; 232 __le16 time, date; 233 int err; 234 235 memcpy(de.name, name, MSDOS_NAME); 236 de.attr = is_dir ? ATTR_DIR : ATTR_ARCH; 237 if (is_hid) 238 de.attr |= ATTR_HIDDEN; 239 de.lcase = 0; 240 fat_time_unix2fat(sbi, ts, &time, &date, NULL); 241 de.cdate = de.adate = 0; 242 de.ctime = 0; 243 de.ctime_cs = 0; 244 de.time = time; 245 de.date = date; 246 fat_set_start(&de, cluster); 247 de.size = 0; 248 249 err = fat_add_entries(dir, &de, 1, sinfo); 250 if (err) 251 return err; 252 253 dir->i_ctime = dir->i_mtime = *ts; 254 if (IS_DIRSYNC(dir)) 255 (void)fat_sync_inode(dir); 256 else 257 mark_inode_dirty(dir); 258 259 return 0; 260 } 261 262 /***** Create a file */ 263 static int msdos_create(struct inode *dir, struct dentry *dentry, umode_t mode, 264 bool excl) 265 { 266 struct super_block *sb = dir->i_sb; 267 struct inode *inode = NULL; 268 struct fat_slot_info sinfo; 269 struct timespec ts; 270 unsigned char msdos_name[MSDOS_NAME]; 271 int err, is_hid; 272 273 mutex_lock(&MSDOS_SB(sb)->s_lock); 274 275 err = msdos_format_name(dentry->d_name.name, dentry->d_name.len, 276 msdos_name, &MSDOS_SB(sb)->options); 277 if (err) 278 goto out; 279 is_hid = (dentry->d_name.name[0] == '.') && (msdos_name[0] != '.'); 280 /* Have to do it due to foo vs. .foo conflicts */ 281 if (!fat_scan(dir, msdos_name, &sinfo)) { 282 brelse(sinfo.bh); 283 err = -EINVAL; 284 goto out; 285 } 286 287 ts = current_time(dir); 288 err = msdos_add_entry(dir, msdos_name, 0, is_hid, 0, &ts, &sinfo); 289 if (err) 290 goto out; 291 inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos); 292 brelse(sinfo.bh); 293 if (IS_ERR(inode)) { 294 err = PTR_ERR(inode); 295 goto out; 296 } 297 inode->i_mtime = inode->i_atime = inode->i_ctime = ts; 298 /* timestamp is already written, so mark_inode_dirty() is unneeded. */ 299 300 d_instantiate(dentry, inode); 301 out: 302 mutex_unlock(&MSDOS_SB(sb)->s_lock); 303 if (!err) 304 err = fat_flush_inodes(sb, dir, inode); 305 return err; 306 } 307 308 /***** Remove a directory */ 309 static int msdos_rmdir(struct inode *dir, struct dentry *dentry) 310 { 311 struct super_block *sb = dir->i_sb; 312 struct inode *inode = d_inode(dentry); 313 struct fat_slot_info sinfo; 314 int err; 315 316 mutex_lock(&MSDOS_SB(sb)->s_lock); 317 /* 318 * Check whether the directory is not in use, then check 319 * whether it is empty. 320 */ 321 err = fat_dir_empty(inode); 322 if (err) 323 goto out; 324 err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo); 325 if (err) 326 goto out; 327 328 err = fat_remove_entries(dir, &sinfo); /* and releases bh */ 329 if (err) 330 goto out; 331 drop_nlink(dir); 332 333 clear_nlink(inode); 334 inode->i_ctime = current_time(inode); 335 fat_detach(inode); 336 out: 337 mutex_unlock(&MSDOS_SB(sb)->s_lock); 338 if (!err) 339 err = fat_flush_inodes(sb, dir, inode); 340 341 return err; 342 } 343 344 /***** Make a directory */ 345 static int msdos_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 346 { 347 struct super_block *sb = dir->i_sb; 348 struct fat_slot_info sinfo; 349 struct inode *inode; 350 unsigned char msdos_name[MSDOS_NAME]; 351 struct timespec ts; 352 int err, is_hid, cluster; 353 354 mutex_lock(&MSDOS_SB(sb)->s_lock); 355 356 err = msdos_format_name(dentry->d_name.name, dentry->d_name.len, 357 msdos_name, &MSDOS_SB(sb)->options); 358 if (err) 359 goto out; 360 is_hid = (dentry->d_name.name[0] == '.') && (msdos_name[0] != '.'); 361 /* foo vs .foo situation */ 362 if (!fat_scan(dir, msdos_name, &sinfo)) { 363 brelse(sinfo.bh); 364 err = -EINVAL; 365 goto out; 366 } 367 368 ts = current_time(dir); 369 cluster = fat_alloc_new_dir(dir, &ts); 370 if (cluster < 0) { 371 err = cluster; 372 goto out; 373 } 374 err = msdos_add_entry(dir, msdos_name, 1, is_hid, cluster, &ts, &sinfo); 375 if (err) 376 goto out_free; 377 inc_nlink(dir); 378 379 inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos); 380 brelse(sinfo.bh); 381 if (IS_ERR(inode)) { 382 err = PTR_ERR(inode); 383 /* the directory was completed, just return a error */ 384 goto out; 385 } 386 set_nlink(inode, 2); 387 inode->i_mtime = inode->i_atime = inode->i_ctime = ts; 388 /* timestamp is already written, so mark_inode_dirty() is unneeded. */ 389 390 d_instantiate(dentry, inode); 391 392 mutex_unlock(&MSDOS_SB(sb)->s_lock); 393 fat_flush_inodes(sb, dir, inode); 394 return 0; 395 396 out_free: 397 fat_free_clusters(dir, cluster); 398 out: 399 mutex_unlock(&MSDOS_SB(sb)->s_lock); 400 return err; 401 } 402 403 /***** Unlink a file */ 404 static int msdos_unlink(struct inode *dir, struct dentry *dentry) 405 { 406 struct inode *inode = d_inode(dentry); 407 struct super_block *sb = inode->i_sb; 408 struct fat_slot_info sinfo; 409 int err; 410 411 mutex_lock(&MSDOS_SB(sb)->s_lock); 412 err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo); 413 if (err) 414 goto out; 415 416 err = fat_remove_entries(dir, &sinfo); /* and releases bh */ 417 if (err) 418 goto out; 419 clear_nlink(inode); 420 inode->i_ctime = current_time(inode); 421 fat_detach(inode); 422 out: 423 mutex_unlock(&MSDOS_SB(sb)->s_lock); 424 if (!err) 425 err = fat_flush_inodes(sb, dir, inode); 426 427 return err; 428 } 429 430 static int do_msdos_rename(struct inode *old_dir, unsigned char *old_name, 431 struct dentry *old_dentry, 432 struct inode *new_dir, unsigned char *new_name, 433 struct dentry *new_dentry, int is_hid) 434 { 435 struct buffer_head *dotdot_bh; 436 struct msdos_dir_entry *dotdot_de; 437 struct inode *old_inode, *new_inode; 438 struct fat_slot_info old_sinfo, sinfo; 439 struct timespec ts; 440 loff_t new_i_pos; 441 int err, old_attrs, is_dir, update_dotdot, corrupt = 0; 442 443 old_sinfo.bh = sinfo.bh = dotdot_bh = NULL; 444 old_inode = d_inode(old_dentry); 445 new_inode = d_inode(new_dentry); 446 447 err = fat_scan(old_dir, old_name, &old_sinfo); 448 if (err) { 449 err = -EIO; 450 goto out; 451 } 452 453 is_dir = S_ISDIR(old_inode->i_mode); 454 update_dotdot = (is_dir && old_dir != new_dir); 455 if (update_dotdot) { 456 if (fat_get_dotdot_entry(old_inode, &dotdot_bh, &dotdot_de)) { 457 err = -EIO; 458 goto out; 459 } 460 } 461 462 old_attrs = MSDOS_I(old_inode)->i_attrs; 463 err = fat_scan(new_dir, new_name, &sinfo); 464 if (!err) { 465 if (!new_inode) { 466 /* "foo" -> ".foo" case. just change the ATTR_HIDDEN */ 467 if (sinfo.de != old_sinfo.de) { 468 err = -EINVAL; 469 goto out; 470 } 471 if (is_hid) 472 MSDOS_I(old_inode)->i_attrs |= ATTR_HIDDEN; 473 else 474 MSDOS_I(old_inode)->i_attrs &= ~ATTR_HIDDEN; 475 if (IS_DIRSYNC(old_dir)) { 476 err = fat_sync_inode(old_inode); 477 if (err) { 478 MSDOS_I(old_inode)->i_attrs = old_attrs; 479 goto out; 480 } 481 } else 482 mark_inode_dirty(old_inode); 483 484 inode_inc_iversion(old_dir); 485 old_dir->i_ctime = old_dir->i_mtime = current_time(old_dir); 486 if (IS_DIRSYNC(old_dir)) 487 (void)fat_sync_inode(old_dir); 488 else 489 mark_inode_dirty(old_dir); 490 goto out; 491 } 492 } 493 494 ts = current_time(old_inode); 495 if (new_inode) { 496 if (err) 497 goto out; 498 if (is_dir) { 499 err = fat_dir_empty(new_inode); 500 if (err) 501 goto out; 502 } 503 new_i_pos = MSDOS_I(new_inode)->i_pos; 504 fat_detach(new_inode); 505 } else { 506 err = msdos_add_entry(new_dir, new_name, is_dir, is_hid, 0, 507 &ts, &sinfo); 508 if (err) 509 goto out; 510 new_i_pos = sinfo.i_pos; 511 } 512 inode_inc_iversion(new_dir); 513 514 fat_detach(old_inode); 515 fat_attach(old_inode, new_i_pos); 516 if (is_hid) 517 MSDOS_I(old_inode)->i_attrs |= ATTR_HIDDEN; 518 else 519 MSDOS_I(old_inode)->i_attrs &= ~ATTR_HIDDEN; 520 if (IS_DIRSYNC(new_dir)) { 521 err = fat_sync_inode(old_inode); 522 if (err) 523 goto error_inode; 524 } else 525 mark_inode_dirty(old_inode); 526 527 if (update_dotdot) { 528 fat_set_start(dotdot_de, MSDOS_I(new_dir)->i_logstart); 529 mark_buffer_dirty_inode(dotdot_bh, old_inode); 530 if (IS_DIRSYNC(new_dir)) { 531 err = sync_dirty_buffer(dotdot_bh); 532 if (err) 533 goto error_dotdot; 534 } 535 drop_nlink(old_dir); 536 if (!new_inode) 537 inc_nlink(new_dir); 538 } 539 540 err = fat_remove_entries(old_dir, &old_sinfo); /* and releases bh */ 541 old_sinfo.bh = NULL; 542 if (err) 543 goto error_dotdot; 544 inode_inc_iversion(old_dir); 545 old_dir->i_ctime = old_dir->i_mtime = ts; 546 if (IS_DIRSYNC(old_dir)) 547 (void)fat_sync_inode(old_dir); 548 else 549 mark_inode_dirty(old_dir); 550 551 if (new_inode) { 552 drop_nlink(new_inode); 553 if (is_dir) 554 drop_nlink(new_inode); 555 new_inode->i_ctime = ts; 556 } 557 out: 558 brelse(sinfo.bh); 559 brelse(dotdot_bh); 560 brelse(old_sinfo.bh); 561 return err; 562 563 error_dotdot: 564 /* data cluster is shared, serious corruption */ 565 corrupt = 1; 566 567 if (update_dotdot) { 568 fat_set_start(dotdot_de, MSDOS_I(old_dir)->i_logstart); 569 mark_buffer_dirty_inode(dotdot_bh, old_inode); 570 corrupt |= sync_dirty_buffer(dotdot_bh); 571 } 572 error_inode: 573 fat_detach(old_inode); 574 fat_attach(old_inode, old_sinfo.i_pos); 575 MSDOS_I(old_inode)->i_attrs = old_attrs; 576 if (new_inode) { 577 fat_attach(new_inode, new_i_pos); 578 if (corrupt) 579 corrupt |= fat_sync_inode(new_inode); 580 } else { 581 /* 582 * If new entry was not sharing the data cluster, it 583 * shouldn't be serious corruption. 584 */ 585 int err2 = fat_remove_entries(new_dir, &sinfo); 586 if (corrupt) 587 corrupt |= err2; 588 sinfo.bh = NULL; 589 } 590 if (corrupt < 0) { 591 fat_fs_error(new_dir->i_sb, 592 "%s: Filesystem corrupted (i_pos %lld)", 593 __func__, sinfo.i_pos); 594 } 595 goto out; 596 } 597 598 /***** Rename, a wrapper for rename_same_dir & rename_diff_dir */ 599 static int msdos_rename(struct inode *old_dir, struct dentry *old_dentry, 600 struct inode *new_dir, struct dentry *new_dentry, 601 unsigned int flags) 602 { 603 struct super_block *sb = old_dir->i_sb; 604 unsigned char old_msdos_name[MSDOS_NAME], new_msdos_name[MSDOS_NAME]; 605 int err, is_hid; 606 607 if (flags & ~RENAME_NOREPLACE) 608 return -EINVAL; 609 610 mutex_lock(&MSDOS_SB(sb)->s_lock); 611 612 err = msdos_format_name(old_dentry->d_name.name, 613 old_dentry->d_name.len, old_msdos_name, 614 &MSDOS_SB(old_dir->i_sb)->options); 615 if (err) 616 goto out; 617 err = msdos_format_name(new_dentry->d_name.name, 618 new_dentry->d_name.len, new_msdos_name, 619 &MSDOS_SB(new_dir->i_sb)->options); 620 if (err) 621 goto out; 622 623 is_hid = 624 (new_dentry->d_name.name[0] == '.') && (new_msdos_name[0] != '.'); 625 626 err = do_msdos_rename(old_dir, old_msdos_name, old_dentry, 627 new_dir, new_msdos_name, new_dentry, is_hid); 628 out: 629 mutex_unlock(&MSDOS_SB(sb)->s_lock); 630 if (!err) 631 err = fat_flush_inodes(sb, old_dir, new_dir); 632 return err; 633 } 634 635 static const struct inode_operations msdos_dir_inode_operations = { 636 .create = msdos_create, 637 .lookup = msdos_lookup, 638 .unlink = msdos_unlink, 639 .mkdir = msdos_mkdir, 640 .rmdir = msdos_rmdir, 641 .rename = msdos_rename, 642 .setattr = fat_setattr, 643 .getattr = fat_getattr, 644 }; 645 646 static void setup(struct super_block *sb) 647 { 648 MSDOS_SB(sb)->dir_ops = &msdos_dir_inode_operations; 649 sb->s_d_op = &msdos_dentry_operations; 650 sb->s_flags |= SB_NOATIME; 651 } 652 653 static int msdos_fill_super(struct super_block *sb, void *data, int silent) 654 { 655 return fat_fill_super(sb, data, silent, 0, setup); 656 } 657 658 static struct dentry *msdos_mount(struct file_system_type *fs_type, 659 int flags, const char *dev_name, 660 void *data) 661 { 662 return mount_bdev(fs_type, flags, dev_name, data, msdos_fill_super); 663 } 664 665 static struct file_system_type msdos_fs_type = { 666 .owner = THIS_MODULE, 667 .name = "msdos", 668 .mount = msdos_mount, 669 .kill_sb = kill_block_super, 670 .fs_flags = FS_REQUIRES_DEV, 671 }; 672 MODULE_ALIAS_FS("msdos"); 673 674 static int __init init_msdos_fs(void) 675 { 676 return register_filesystem(&msdos_fs_type); 677 } 678 679 static void __exit exit_msdos_fs(void) 680 { 681 unregister_filesystem(&msdos_fs_type); 682 } 683 684 MODULE_LICENSE("GPL"); 685 MODULE_AUTHOR("Werner Almesberger"); 686 MODULE_DESCRIPTION("MS-DOS filesystem support"); 687 688 module_init(init_msdos_fs) 689 module_exit(exit_msdos_fs) 690