1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * linux/fs/ext4/dir.c 4 * 5 * Copyright (C) 1992, 1993, 1994, 1995 6 * Remy Card (card@masi.ibp.fr) 7 * Laboratoire MASI - Institut Blaise Pascal 8 * Universite Pierre et Marie Curie (Paris VI) 9 * 10 * from 11 * 12 * linux/fs/minix/dir.c 13 * 14 * Copyright (C) 1991, 1992 Linus Torvalds 15 * 16 * ext4 directory handling functions 17 * 18 * Big-endian to little-endian byte-swapping/bitmaps by 19 * David S. Miller (davem@caip.rutgers.edu), 1995 20 * 21 * Hash Tree Directory indexing (c) 2001 Daniel Phillips 22 * 23 */ 24 25 #include <linux/fs.h> 26 #include <linux/buffer_head.h> 27 #include <linux/slab.h> 28 #include <linux/iversion.h> 29 #include <linux/unicode.h> 30 #include "ext4.h" 31 #include "xattr.h" 32 33 static int ext4_dx_readdir(struct file *, struct dir_context *); 34 35 /** 36 * is_dx_dir() - check if a directory is using htree indexing 37 * @inode: directory inode 38 * 39 * Check if the given dir-inode refers to an htree-indexed directory 40 * (or a directory which could potentially get converted to use htree 41 * indexing). 42 * 43 * Return 1 if it is a dx dir, 0 if not 44 */ 45 static int is_dx_dir(struct inode *inode) 46 { 47 struct super_block *sb = inode->i_sb; 48 49 if (ext4_has_feature_dir_index(inode->i_sb) && 50 ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) || 51 ((inode->i_size >> sb->s_blocksize_bits) == 1) || 52 ext4_has_inline_data(inode))) 53 return 1; 54 55 return 0; 56 } 57 58 static bool is_fake_dir_entry(struct ext4_dir_entry_2 *de) 59 { 60 /* Check if . or .. , or skip if namelen is 0 */ 61 if ((de->name_len > 0) && (de->name_len <= 2) && (de->name[0] == '.') && 62 (de->name[1] == '.' || de->name[1] == '\0')) 63 return true; 64 /* Check if this is a csum entry */ 65 if (de->file_type == EXT4_FT_DIR_CSUM) 66 return true; 67 return false; 68 } 69 70 /* 71 * Return 0 if the directory entry is OK, and 1 if there is a problem 72 * 73 * Note: this is the opposite of what ext2 and ext3 historically returned... 74 * 75 * bh passed here can be an inode block or a dir data block, depending 76 * on the inode inline data flag. 77 */ 78 int __ext4_check_dir_entry(const char *function, unsigned int line, 79 struct inode *dir, struct file *filp, 80 struct ext4_dir_entry_2 *de, 81 struct buffer_head *bh, char *buf, int size, 82 unsigned int offset) 83 { 84 const char *error_msg = NULL; 85 const int rlen = ext4_rec_len_from_disk(de->rec_len, 86 dir->i_sb->s_blocksize); 87 const int next_offset = ((char *) de - buf) + rlen; 88 bool fake = is_fake_dir_entry(de); 89 bool has_csum = ext4_has_feature_metadata_csum(dir->i_sb); 90 91 if (unlikely(rlen < ext4_dir_rec_len(1, fake ? NULL : dir))) 92 error_msg = "rec_len is smaller than minimal"; 93 else if (unlikely(rlen % 4 != 0)) 94 error_msg = "rec_len % 4 != 0"; 95 else if (unlikely(rlen < ext4_dir_rec_len(de->name_len, 96 fake ? NULL : dir))) 97 error_msg = "rec_len is too small for name_len"; 98 else if (unlikely(next_offset > size)) 99 error_msg = "directory entry overrun"; 100 else if (unlikely(next_offset > size - ext4_dir_rec_len(1, 101 has_csum ? NULL : dir) && 102 next_offset != size)) 103 error_msg = "directory entry too close to block end"; 104 else if (unlikely(le32_to_cpu(de->inode) > 105 le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count))) 106 error_msg = "inode out of bounds"; 107 else if (unlikely(next_offset == size && de->name_len == 1 && 108 de->name[0] == '.')) 109 error_msg = "'.' directory cannot be the last in data block"; 110 else 111 return 0; 112 113 if (filp) 114 ext4_error_file(filp, function, line, bh->b_blocknr, 115 "bad entry in directory: %s - offset=%u, " 116 "inode=%u, rec_len=%d, size=%d fake=%d", 117 error_msg, offset, le32_to_cpu(de->inode), 118 rlen, size, fake); 119 else 120 ext4_error_inode(dir, function, line, bh->b_blocknr, 121 "bad entry in directory: %s - offset=%u, " 122 "inode=%u, rec_len=%d, size=%d fake=%d", 123 error_msg, offset, le32_to_cpu(de->inode), 124 rlen, size, fake); 125 126 return 1; 127 } 128 129 static int ext4_readdir(struct file *file, struct dir_context *ctx) 130 { 131 unsigned int offset; 132 int i; 133 struct ext4_dir_entry_2 *de; 134 int err; 135 struct inode *inode = file_inode(file); 136 struct super_block *sb = inode->i_sb; 137 struct buffer_head *bh = NULL; 138 struct fscrypt_str fstr = FSTR_INIT(NULL, 0); 139 struct dir_private_info *info = file->private_data; 140 141 err = fscrypt_prepare_readdir(inode); 142 if (err) 143 return err; 144 145 if (is_dx_dir(inode)) { 146 err = ext4_dx_readdir(file, ctx); 147 if (err != ERR_BAD_DX_DIR) 148 return err; 149 150 /* Can we just clear INDEX flag to ignore htree information? */ 151 if (!ext4_has_feature_metadata_csum(sb)) { 152 /* 153 * We don't set the inode dirty flag since it's not 154 * critical that it gets flushed back to the disk. 155 */ 156 ext4_clear_inode_flag(inode, EXT4_INODE_INDEX); 157 } 158 } 159 160 if (ext4_has_inline_data(inode)) { 161 int has_inline_data = 1; 162 err = ext4_read_inline_dir(file, ctx, 163 &has_inline_data); 164 if (has_inline_data) 165 return err; 166 } 167 168 if (IS_ENCRYPTED(inode)) { 169 err = fscrypt_fname_alloc_buffer(EXT4_NAME_LEN, &fstr); 170 if (err < 0) 171 return err; 172 } 173 174 while (ctx->pos < inode->i_size) { 175 struct ext4_map_blocks map; 176 177 if (fatal_signal_pending(current)) { 178 err = -ERESTARTSYS; 179 goto errout; 180 } 181 cond_resched(); 182 offset = ctx->pos & (sb->s_blocksize - 1); 183 map.m_lblk = ctx->pos >> EXT4_BLOCK_SIZE_BITS(sb); 184 map.m_len = 1; 185 err = ext4_map_blocks(NULL, inode, &map, 0); 186 if (err == 0) { 187 /* m_len should never be zero but let's avoid 188 * an infinite loop if it somehow is */ 189 if (map.m_len == 0) 190 map.m_len = 1; 191 ctx->pos += map.m_len * sb->s_blocksize; 192 continue; 193 } 194 if (err > 0) { 195 pgoff_t index = map.m_pblk >> 196 (PAGE_SHIFT - inode->i_blkbits); 197 if (!ra_has_index(&file->f_ra, index)) 198 page_cache_sync_readahead( 199 sb->s_bdev->bd_mapping, 200 &file->f_ra, file, 201 index, 1); 202 file->f_ra.prev_pos = (loff_t)index << PAGE_SHIFT; 203 bh = ext4_bread(NULL, inode, map.m_lblk, 0); 204 if (IS_ERR(bh)) { 205 err = PTR_ERR(bh); 206 bh = NULL; 207 goto errout; 208 } 209 } 210 211 if (!bh) { 212 /* corrupt size? Maybe no more blocks to read */ 213 if (ctx->pos > inode->i_blocks << 9) 214 break; 215 ctx->pos += sb->s_blocksize - offset; 216 continue; 217 } 218 219 /* Check the checksum */ 220 if (!buffer_verified(bh) && 221 !ext4_dirblock_csum_verify(inode, bh)) { 222 EXT4_ERROR_FILE(file, 0, "directory fails checksum " 223 "at offset %llu", 224 (unsigned long long)ctx->pos); 225 ctx->pos += sb->s_blocksize - offset; 226 brelse(bh); 227 bh = NULL; 228 continue; 229 } 230 set_buffer_verified(bh); 231 232 /* If the dir block has changed since the last call to 233 * readdir(2), then we might be pointing to an invalid 234 * dirent right now. Scan from the start of the block 235 * to make sure. */ 236 if (!inode_eq_iversion(inode, info->cookie)) { 237 for (i = 0; i < sb->s_blocksize && i < offset; ) { 238 de = (struct ext4_dir_entry_2 *) 239 (bh->b_data + i); 240 /* It's too expensive to do a full 241 * dirent test each time round this 242 * loop, but we do have to test at 243 * least that it is non-zero. A 244 * failure will be detected in the 245 * dirent test below. */ 246 if (ext4_rec_len_from_disk(de->rec_len, 247 sb->s_blocksize) < ext4_dir_rec_len(1, 248 inode)) 249 break; 250 i += ext4_rec_len_from_disk(de->rec_len, 251 sb->s_blocksize); 252 } 253 offset = i; 254 ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1)) 255 | offset; 256 info->cookie = inode_query_iversion(inode); 257 } 258 259 while (ctx->pos < inode->i_size 260 && offset < sb->s_blocksize) { 261 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset); 262 if (ext4_check_dir_entry(inode, file, de, bh, 263 bh->b_data, bh->b_size, 264 offset)) { 265 /* 266 * On error, skip to the next block 267 */ 268 ctx->pos = (ctx->pos | 269 (sb->s_blocksize - 1)) + 1; 270 break; 271 } 272 offset += ext4_rec_len_from_disk(de->rec_len, 273 sb->s_blocksize); 274 if (le32_to_cpu(de->inode)) { 275 if (!IS_ENCRYPTED(inode)) { 276 if (!dir_emit(ctx, de->name, 277 de->name_len, 278 le32_to_cpu(de->inode), 279 get_dtype(sb, de->file_type))) 280 goto done; 281 } else { 282 int save_len = fstr.len; 283 struct fscrypt_str de_name = 284 FSTR_INIT(de->name, 285 de->name_len); 286 u32 hash; 287 u32 minor_hash; 288 289 if (IS_CASEFOLDED(inode)) { 290 hash = EXT4_DIRENT_HASH(de); 291 minor_hash = EXT4_DIRENT_MINOR_HASH(de); 292 } else { 293 hash = 0; 294 minor_hash = 0; 295 } 296 297 /* Directory is encrypted */ 298 err = fscrypt_fname_disk_to_usr(inode, 299 hash, minor_hash, &de_name, &fstr); 300 de_name = fstr; 301 fstr.len = save_len; 302 if (err) 303 goto errout; 304 if (!dir_emit(ctx, 305 de_name.name, de_name.len, 306 le32_to_cpu(de->inode), 307 get_dtype(sb, de->file_type))) 308 goto done; 309 } 310 } 311 ctx->pos += ext4_rec_len_from_disk(de->rec_len, 312 sb->s_blocksize); 313 } 314 if ((ctx->pos < inode->i_size) && !dir_relax_shared(inode)) 315 goto done; 316 brelse(bh); 317 bh = NULL; 318 } 319 done: 320 err = 0; 321 errout: 322 fscrypt_fname_free_buffer(&fstr); 323 brelse(bh); 324 return err; 325 } 326 327 static inline int is_32bit_api(void) 328 { 329 #ifdef CONFIG_COMPAT 330 return in_compat_syscall(); 331 #else 332 return (BITS_PER_LONG == 32); 333 #endif 334 } 335 336 /* 337 * These functions convert from the major/minor hash to an f_pos 338 * value for dx directories 339 * 340 * Upper layer (for example NFS) should specify FMODE_32BITHASH or 341 * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted 342 * directly on both 32-bit and 64-bit nodes, under such case, neither 343 * FMODE_32BITHASH nor FMODE_64BITHASH is specified. 344 */ 345 static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor) 346 { 347 if ((filp->f_mode & FMODE_32BITHASH) || 348 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 349 return major >> 1; 350 else 351 return ((__u64)(major >> 1) << 32) | (__u64)minor; 352 } 353 354 static inline __u32 pos2maj_hash(struct file *filp, loff_t pos) 355 { 356 if ((filp->f_mode & FMODE_32BITHASH) || 357 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 358 return (pos << 1) & 0xffffffff; 359 else 360 return ((pos >> 32) << 1) & 0xffffffff; 361 } 362 363 static inline __u32 pos2min_hash(struct file *filp, loff_t pos) 364 { 365 if ((filp->f_mode & FMODE_32BITHASH) || 366 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 367 return 0; 368 else 369 return pos & 0xffffffff; 370 } 371 372 /* 373 * Return 32- or 64-bit end-of-file for dx directories 374 */ 375 static inline loff_t ext4_get_htree_eof(struct file *filp) 376 { 377 if ((filp->f_mode & FMODE_32BITHASH) || 378 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 379 return EXT4_HTREE_EOF_32BIT; 380 else 381 return EXT4_HTREE_EOF_64BIT; 382 } 383 384 385 /* 386 * ext4_dir_llseek() calls generic_file_llseek_size to handle htree 387 * directories, where the "offset" is in terms of the filename hash 388 * value instead of the byte offset. 389 * 390 * Because we may return a 64-bit hash that is well beyond offset limits, 391 * we need to pass the max hash as the maximum allowable offset in 392 * the htree directory case. 393 * 394 * For non-htree, ext4_llseek already chooses the proper max offset. 395 */ 396 static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence) 397 { 398 struct inode *inode = file->f_mapping->host; 399 struct dir_private_info *info = file->private_data; 400 int dx_dir = is_dx_dir(inode); 401 loff_t ret, htree_max = ext4_get_htree_eof(file); 402 403 if (likely(dx_dir)) 404 ret = generic_file_llseek_size(file, offset, whence, 405 htree_max, htree_max); 406 else 407 ret = ext4_llseek(file, offset, whence); 408 info->cookie = inode_peek_iversion(inode) - 1; 409 return ret; 410 } 411 412 /* 413 * This structure holds the nodes of the red-black tree used to store 414 * the directory entry in hash order. 415 */ 416 struct fname { 417 __u32 hash; 418 __u32 minor_hash; 419 struct rb_node rb_hash; 420 struct fname *next; 421 __u32 inode; 422 __u8 name_len; 423 __u8 file_type; 424 char name[] __counted_by(name_len); 425 }; 426 427 /* 428 * This function implements a non-recursive way of freeing all of the 429 * nodes in the red-black tree. 430 */ 431 static void free_rb_tree_fname(struct rb_root *root) 432 { 433 struct fname *fname, *next; 434 435 rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash) 436 while (fname) { 437 struct fname *old = fname; 438 fname = fname->next; 439 kfree(old); 440 } 441 442 *root = RB_ROOT; 443 } 444 445 static void ext4_htree_init_dir_info(struct file *filp, loff_t pos) 446 { 447 struct dir_private_info *p = filp->private_data; 448 449 if (is_dx_dir(file_inode(filp)) && !p->initialized) { 450 p->curr_hash = pos2maj_hash(filp, pos); 451 p->curr_minor_hash = pos2min_hash(filp, pos); 452 p->initialized = true; 453 } 454 } 455 456 void ext4_htree_free_dir_info(struct dir_private_info *p) 457 { 458 free_rb_tree_fname(&p->root); 459 kfree(p); 460 } 461 462 /* 463 * Given a directory entry, enter it into the fname rb tree. 464 * 465 * When filename encryption is enabled, the dirent will hold the 466 * encrypted filename, while the htree will hold decrypted filename. 467 * The decrypted filename is passed in via ent_name. parameter. 468 */ 469 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash, 470 __u32 minor_hash, 471 struct ext4_dir_entry_2 *dirent, 472 struct fscrypt_str *ent_name) 473 { 474 struct rb_node **p, *parent = NULL; 475 struct fname *fname, *new_fn; 476 struct dir_private_info *info; 477 478 info = dir_file->private_data; 479 p = &info->root.rb_node; 480 481 /* Create and allocate the fname structure */ 482 new_fn = kzalloc(struct_size(new_fn, name, ent_name->len + 1), 483 GFP_KERNEL); 484 if (!new_fn) 485 return -ENOMEM; 486 new_fn->hash = hash; 487 new_fn->minor_hash = minor_hash; 488 new_fn->inode = le32_to_cpu(dirent->inode); 489 new_fn->name_len = ent_name->len; 490 new_fn->file_type = dirent->file_type; 491 memcpy(new_fn->name, ent_name->name, ent_name->len); 492 493 while (*p) { 494 parent = *p; 495 fname = rb_entry(parent, struct fname, rb_hash); 496 497 /* 498 * If the hash and minor hash match up, then we put 499 * them on a linked list. This rarely happens... 500 */ 501 if ((new_fn->hash == fname->hash) && 502 (new_fn->minor_hash == fname->minor_hash)) { 503 new_fn->next = fname->next; 504 fname->next = new_fn; 505 return 0; 506 } 507 508 if (new_fn->hash < fname->hash) 509 p = &(*p)->rb_left; 510 else if (new_fn->hash > fname->hash) 511 p = &(*p)->rb_right; 512 else if (new_fn->minor_hash < fname->minor_hash) 513 p = &(*p)->rb_left; 514 else /* if (new_fn->minor_hash > fname->minor_hash) */ 515 p = &(*p)->rb_right; 516 } 517 518 rb_link_node(&new_fn->rb_hash, parent, p); 519 rb_insert_color(&new_fn->rb_hash, &info->root); 520 return 0; 521 } 522 523 524 525 /* 526 * This is a helper function for ext4_dx_readdir. It calls filldir 527 * for all entries on the fname linked list. (Normally there is only 528 * one entry on the linked list, unless there are 62 bit hash collisions.) 529 */ 530 static int call_filldir(struct file *file, struct dir_context *ctx, 531 struct fname *fname) 532 { 533 struct dir_private_info *info = file->private_data; 534 struct inode *inode = file_inode(file); 535 struct super_block *sb = inode->i_sb; 536 537 if (!fname) { 538 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: " 539 "called with null fname?!?", __func__, __LINE__, 540 inode->i_ino, current->comm); 541 return 0; 542 } 543 ctx->pos = hash2pos(file, fname->hash, fname->minor_hash); 544 while (fname) { 545 if (!dir_emit(ctx, fname->name, 546 fname->name_len, 547 fname->inode, 548 get_dtype(sb, fname->file_type))) { 549 info->extra_fname = fname; 550 return 1; 551 } 552 fname = fname->next; 553 } 554 return 0; 555 } 556 557 static int ext4_dx_readdir(struct file *file, struct dir_context *ctx) 558 { 559 struct dir_private_info *info = file->private_data; 560 struct inode *inode = file_inode(file); 561 struct fname *fname; 562 int ret = 0; 563 564 ext4_htree_init_dir_info(file, ctx->pos); 565 566 if (ctx->pos == ext4_get_htree_eof(file)) 567 return 0; /* EOF */ 568 569 /* Some one has messed with f_pos; reset the world */ 570 if (info->last_pos != ctx->pos) { 571 free_rb_tree_fname(&info->root); 572 info->curr_node = NULL; 573 info->extra_fname = NULL; 574 info->curr_hash = pos2maj_hash(file, ctx->pos); 575 info->curr_minor_hash = pos2min_hash(file, ctx->pos); 576 } 577 578 /* 579 * If there are any leftover names on the hash collision 580 * chain, return them first. 581 */ 582 if (info->extra_fname) { 583 if (call_filldir(file, ctx, info->extra_fname)) 584 goto finished; 585 info->extra_fname = NULL; 586 goto next_node; 587 } else if (!info->curr_node) 588 info->curr_node = rb_first(&info->root); 589 590 while (1) { 591 /* 592 * Fill the rbtree if we have no more entries, 593 * or the inode has changed since we last read in the 594 * cached entries. 595 */ 596 if ((!info->curr_node) || 597 !inode_eq_iversion(inode, info->cookie)) { 598 info->curr_node = NULL; 599 free_rb_tree_fname(&info->root); 600 info->cookie = inode_query_iversion(inode); 601 ret = ext4_htree_fill_tree(file, info->curr_hash, 602 info->curr_minor_hash, 603 &info->next_hash); 604 if (ret < 0) 605 goto finished; 606 if (ret == 0) { 607 ctx->pos = ext4_get_htree_eof(file); 608 break; 609 } 610 info->curr_node = rb_first(&info->root); 611 } 612 613 fname = rb_entry(info->curr_node, struct fname, rb_hash); 614 info->curr_hash = fname->hash; 615 info->curr_minor_hash = fname->minor_hash; 616 if (call_filldir(file, ctx, fname)) 617 break; 618 next_node: 619 info->curr_node = rb_next(info->curr_node); 620 if (info->curr_node) { 621 fname = rb_entry(info->curr_node, struct fname, 622 rb_hash); 623 info->curr_hash = fname->hash; 624 info->curr_minor_hash = fname->minor_hash; 625 } else { 626 if (info->next_hash == ~0) { 627 ctx->pos = ext4_get_htree_eof(file); 628 break; 629 } 630 info->curr_hash = info->next_hash; 631 info->curr_minor_hash = 0; 632 } 633 } 634 finished: 635 info->last_pos = ctx->pos; 636 return ret < 0 ? ret : 0; 637 } 638 639 static int ext4_release_dir(struct inode *inode, struct file *filp) 640 { 641 if (filp->private_data) 642 ext4_htree_free_dir_info(filp->private_data); 643 644 return 0; 645 } 646 647 int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf, 648 int buf_size) 649 { 650 struct ext4_dir_entry_2 *de; 651 int rlen; 652 unsigned int offset = 0; 653 char *top; 654 655 de = buf; 656 top = buf + buf_size; 657 while ((char *) de < top) { 658 if (ext4_check_dir_entry(dir, NULL, de, bh, 659 buf, buf_size, offset)) 660 return -EFSCORRUPTED; 661 rlen = ext4_rec_len_from_disk(de->rec_len, buf_size); 662 de = (struct ext4_dir_entry_2 *)((char *)de + rlen); 663 offset += rlen; 664 } 665 if ((char *) de > top) 666 return -EFSCORRUPTED; 667 668 return 0; 669 } 670 671 static int ext4_dir_open(struct inode *inode, struct file *file) 672 { 673 struct dir_private_info *info; 674 675 info = kzalloc(sizeof(*info), GFP_KERNEL); 676 if (!info) 677 return -ENOMEM; 678 file->private_data = info; 679 return 0; 680 } 681 682 const struct file_operations ext4_dir_operations = { 683 .open = ext4_dir_open, 684 .llseek = ext4_dir_llseek, 685 .read = generic_read_dir, 686 .iterate_shared = ext4_readdir, 687 .unlocked_ioctl = ext4_ioctl, 688 #ifdef CONFIG_COMPAT 689 .compat_ioctl = ext4_compat_ioctl, 690 #endif 691 .fsync = ext4_sync_file, 692 .release = ext4_release_dir, 693 }; 694