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 = timespec_to_timespec64(*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 timespec64 ts; 270 struct timespec t; 271 unsigned char msdos_name[MSDOS_NAME]; 272 int err, is_hid; 273 274 mutex_lock(&MSDOS_SB(sb)->s_lock); 275 276 err = msdos_format_name(dentry->d_name.name, dentry->d_name.len, 277 msdos_name, &MSDOS_SB(sb)->options); 278 if (err) 279 goto out; 280 is_hid = (dentry->d_name.name[0] == '.') && (msdos_name[0] != '.'); 281 /* Have to do it due to foo vs. .foo conflicts */ 282 if (!fat_scan(dir, msdos_name, &sinfo)) { 283 brelse(sinfo.bh); 284 err = -EINVAL; 285 goto out; 286 } 287 288 ts = current_time(dir); 289 t = timespec64_to_timespec(ts); 290 err = msdos_add_entry(dir, msdos_name, 0, is_hid, 0, &t, &sinfo); 291 if (err) 292 goto out; 293 inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos); 294 brelse(sinfo.bh); 295 if (IS_ERR(inode)) { 296 err = PTR_ERR(inode); 297 goto out; 298 } 299 inode->i_mtime = inode->i_atime = inode->i_ctime = ts; 300 /* timestamp is already written, so mark_inode_dirty() is unneeded. */ 301 302 d_instantiate(dentry, inode); 303 out: 304 mutex_unlock(&MSDOS_SB(sb)->s_lock); 305 if (!err) 306 err = fat_flush_inodes(sb, dir, inode); 307 return err; 308 } 309 310 /***** Remove a directory */ 311 static int msdos_rmdir(struct inode *dir, struct dentry *dentry) 312 { 313 struct super_block *sb = dir->i_sb; 314 struct inode *inode = d_inode(dentry); 315 struct fat_slot_info sinfo; 316 int err; 317 318 mutex_lock(&MSDOS_SB(sb)->s_lock); 319 err = fat_dir_empty(inode); 320 if (err) 321 goto out; 322 err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo); 323 if (err) 324 goto out; 325 326 err = fat_remove_entries(dir, &sinfo); /* and releases bh */ 327 if (err) 328 goto out; 329 drop_nlink(dir); 330 331 clear_nlink(inode); 332 inode->i_ctime = current_time(inode); 333 fat_detach(inode); 334 out: 335 mutex_unlock(&MSDOS_SB(sb)->s_lock); 336 if (!err) 337 err = fat_flush_inodes(sb, dir, inode); 338 339 return err; 340 } 341 342 /***** Make a directory */ 343 static int msdos_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 344 { 345 struct super_block *sb = dir->i_sb; 346 struct fat_slot_info sinfo; 347 struct inode *inode; 348 unsigned char msdos_name[MSDOS_NAME]; 349 struct timespec64 ts; 350 struct timespec t; 351 int err, is_hid, cluster; 352 353 mutex_lock(&MSDOS_SB(sb)->s_lock); 354 355 err = msdos_format_name(dentry->d_name.name, dentry->d_name.len, 356 msdos_name, &MSDOS_SB(sb)->options); 357 if (err) 358 goto out; 359 is_hid = (dentry->d_name.name[0] == '.') && (msdos_name[0] != '.'); 360 /* foo vs .foo situation */ 361 if (!fat_scan(dir, msdos_name, &sinfo)) { 362 brelse(sinfo.bh); 363 err = -EINVAL; 364 goto out; 365 } 366 367 ts = current_time(dir); 368 t = timespec64_to_timespec(ts); 369 cluster = fat_alloc_new_dir(dir, &t); 370 if (cluster < 0) { 371 err = cluster; 372 goto out; 373 } 374 err = msdos_add_entry(dir, msdos_name, 1, is_hid, cluster, &t, &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 timespec64 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 struct timespec t = timespec64_to_timespec(ts); 507 err = msdos_add_entry(new_dir, new_name, is_dir, is_hid, 0, 508 &t, &sinfo); 509 if (err) 510 goto out; 511 new_i_pos = sinfo.i_pos; 512 } 513 inode_inc_iversion(new_dir); 514 515 fat_detach(old_inode); 516 fat_attach(old_inode, new_i_pos); 517 if (is_hid) 518 MSDOS_I(old_inode)->i_attrs |= ATTR_HIDDEN; 519 else 520 MSDOS_I(old_inode)->i_attrs &= ~ATTR_HIDDEN; 521 if (IS_DIRSYNC(new_dir)) { 522 err = fat_sync_inode(old_inode); 523 if (err) 524 goto error_inode; 525 } else 526 mark_inode_dirty(old_inode); 527 528 if (update_dotdot) { 529 fat_set_start(dotdot_de, MSDOS_I(new_dir)->i_logstart); 530 mark_buffer_dirty_inode(dotdot_bh, old_inode); 531 if (IS_DIRSYNC(new_dir)) { 532 err = sync_dirty_buffer(dotdot_bh); 533 if (err) 534 goto error_dotdot; 535 } 536 drop_nlink(old_dir); 537 if (!new_inode) 538 inc_nlink(new_dir); 539 } 540 541 err = fat_remove_entries(old_dir, &old_sinfo); /* and releases bh */ 542 old_sinfo.bh = NULL; 543 if (err) 544 goto error_dotdot; 545 inode_inc_iversion(old_dir); 546 old_dir->i_ctime = old_dir->i_mtime = ts; 547 if (IS_DIRSYNC(old_dir)) 548 (void)fat_sync_inode(old_dir); 549 else 550 mark_inode_dirty(old_dir); 551 552 if (new_inode) { 553 drop_nlink(new_inode); 554 if (is_dir) 555 drop_nlink(new_inode); 556 new_inode->i_ctime = ts; 557 } 558 out: 559 brelse(sinfo.bh); 560 brelse(dotdot_bh); 561 brelse(old_sinfo.bh); 562 return err; 563 564 error_dotdot: 565 /* data cluster is shared, serious corruption */ 566 corrupt = 1; 567 568 if (update_dotdot) { 569 fat_set_start(dotdot_de, MSDOS_I(old_dir)->i_logstart); 570 mark_buffer_dirty_inode(dotdot_bh, old_inode); 571 corrupt |= sync_dirty_buffer(dotdot_bh); 572 } 573 error_inode: 574 fat_detach(old_inode); 575 fat_attach(old_inode, old_sinfo.i_pos); 576 MSDOS_I(old_inode)->i_attrs = old_attrs; 577 if (new_inode) { 578 fat_attach(new_inode, new_i_pos); 579 if (corrupt) 580 corrupt |= fat_sync_inode(new_inode); 581 } else { 582 /* 583 * If new entry was not sharing the data cluster, it 584 * shouldn't be serious corruption. 585 */ 586 int err2 = fat_remove_entries(new_dir, &sinfo); 587 if (corrupt) 588 corrupt |= err2; 589 sinfo.bh = NULL; 590 } 591 if (corrupt < 0) { 592 fat_fs_error(new_dir->i_sb, 593 "%s: Filesystem corrupted (i_pos %lld)", 594 __func__, sinfo.i_pos); 595 } 596 goto out; 597 } 598 599 /***** Rename, a wrapper for rename_same_dir & rename_diff_dir */ 600 static int msdos_rename(struct inode *old_dir, struct dentry *old_dentry, 601 struct inode *new_dir, struct dentry *new_dentry, 602 unsigned int flags) 603 { 604 struct super_block *sb = old_dir->i_sb; 605 unsigned char old_msdos_name[MSDOS_NAME], new_msdos_name[MSDOS_NAME]; 606 int err, is_hid; 607 608 if (flags & ~RENAME_NOREPLACE) 609 return -EINVAL; 610 611 mutex_lock(&MSDOS_SB(sb)->s_lock); 612 613 err = msdos_format_name(old_dentry->d_name.name, 614 old_dentry->d_name.len, old_msdos_name, 615 &MSDOS_SB(old_dir->i_sb)->options); 616 if (err) 617 goto out; 618 err = msdos_format_name(new_dentry->d_name.name, 619 new_dentry->d_name.len, new_msdos_name, 620 &MSDOS_SB(new_dir->i_sb)->options); 621 if (err) 622 goto out; 623 624 is_hid = 625 (new_dentry->d_name.name[0] == '.') && (new_msdos_name[0] != '.'); 626 627 err = do_msdos_rename(old_dir, old_msdos_name, old_dentry, 628 new_dir, new_msdos_name, new_dentry, is_hid); 629 out: 630 mutex_unlock(&MSDOS_SB(sb)->s_lock); 631 if (!err) 632 err = fat_flush_inodes(sb, old_dir, new_dir); 633 return err; 634 } 635 636 static const struct inode_operations msdos_dir_inode_operations = { 637 .create = msdos_create, 638 .lookup = msdos_lookup, 639 .unlink = msdos_unlink, 640 .mkdir = msdos_mkdir, 641 .rmdir = msdos_rmdir, 642 .rename = msdos_rename, 643 .setattr = fat_setattr, 644 .getattr = fat_getattr, 645 }; 646 647 static void setup(struct super_block *sb) 648 { 649 MSDOS_SB(sb)->dir_ops = &msdos_dir_inode_operations; 650 sb->s_d_op = &msdos_dentry_operations; 651 sb->s_flags |= SB_NOATIME; 652 } 653 654 static int msdos_fill_super(struct super_block *sb, void *data, int silent) 655 { 656 return fat_fill_super(sb, data, silent, 0, setup); 657 } 658 659 static struct dentry *msdos_mount(struct file_system_type *fs_type, 660 int flags, const char *dev_name, 661 void *data) 662 { 663 return mount_bdev(fs_type, flags, dev_name, data, msdos_fill_super); 664 } 665 666 static struct file_system_type msdos_fs_type = { 667 .owner = THIS_MODULE, 668 .name = "msdos", 669 .mount = msdos_mount, 670 .kill_sb = kill_block_super, 671 .fs_flags = FS_REQUIRES_DEV, 672 }; 673 MODULE_ALIAS_FS("msdos"); 674 675 static int __init init_msdos_fs(void) 676 { 677 return register_filesystem(&msdos_fs_type); 678 } 679 680 static void __exit exit_msdos_fs(void) 681 { 682 unregister_filesystem(&msdos_fs_type); 683 } 684 685 MODULE_LICENSE("GPL"); 686 MODULE_AUTHOR("Werner Almesberger"); 687 MODULE_DESCRIPTION("MS-DOS filesystem support"); 688 689 module_init(init_msdos_fs) 690 module_exit(exit_msdos_fs) 691