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_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 108 return 0; 109 110 if (filp) 111 ext4_error_file(filp, function, line, bh->b_blocknr, 112 "bad entry in directory: %s - offset=%u, " 113 "inode=%u, rec_len=%d, size=%d fake=%d", 114 error_msg, offset, le32_to_cpu(de->inode), 115 rlen, size, fake); 116 else 117 ext4_error_inode(dir, function, line, bh->b_blocknr, 118 "bad entry in directory: %s - offset=%u, " 119 "inode=%u, rec_len=%d, size=%d fake=%d", 120 error_msg, offset, le32_to_cpu(de->inode), 121 rlen, size, fake); 122 123 return 1; 124 } 125 126 static int ext4_readdir(struct file *file, struct dir_context *ctx) 127 { 128 unsigned int offset; 129 int i; 130 struct ext4_dir_entry_2 *de; 131 int err; 132 struct inode *inode = file_inode(file); 133 struct super_block *sb = inode->i_sb; 134 struct buffer_head *bh = NULL; 135 struct fscrypt_str fstr = FSTR_INIT(NULL, 0); 136 137 err = fscrypt_prepare_readdir(inode); 138 if (err) 139 return err; 140 141 if (is_dx_dir(inode)) { 142 err = ext4_dx_readdir(file, ctx); 143 if (err != ERR_BAD_DX_DIR) 144 return err; 145 146 /* Can we just clear INDEX flag to ignore htree information? */ 147 if (!ext4_has_metadata_csum(sb)) { 148 /* 149 * We don't set the inode dirty flag since it's not 150 * critical that it gets flushed back to the disk. 151 */ 152 ext4_clear_inode_flag(inode, EXT4_INODE_INDEX); 153 } 154 } 155 156 if (ext4_has_inline_data(inode)) { 157 int has_inline_data = 1; 158 err = ext4_read_inline_dir(file, ctx, 159 &has_inline_data); 160 if (has_inline_data) 161 return err; 162 } 163 164 if (IS_ENCRYPTED(inode)) { 165 err = fscrypt_fname_alloc_buffer(EXT4_NAME_LEN, &fstr); 166 if (err < 0) 167 return err; 168 } 169 170 while (ctx->pos < inode->i_size) { 171 struct ext4_map_blocks map; 172 173 if (fatal_signal_pending(current)) { 174 err = -ERESTARTSYS; 175 goto errout; 176 } 177 cond_resched(); 178 offset = ctx->pos & (sb->s_blocksize - 1); 179 map.m_lblk = ctx->pos >> EXT4_BLOCK_SIZE_BITS(sb); 180 map.m_len = 1; 181 err = ext4_map_blocks(NULL, inode, &map, 0); 182 if (err == 0) { 183 /* m_len should never be zero but let's avoid 184 * an infinite loop if it somehow is */ 185 if (map.m_len == 0) 186 map.m_len = 1; 187 ctx->pos += map.m_len * sb->s_blocksize; 188 continue; 189 } 190 if (err > 0) { 191 pgoff_t index = map.m_pblk >> 192 (PAGE_SHIFT - inode->i_blkbits); 193 if (!ra_has_index(&file->f_ra, index)) 194 page_cache_sync_readahead( 195 sb->s_bdev->bd_inode->i_mapping, 196 &file->f_ra, file, 197 index, 1); 198 file->f_ra.prev_pos = (loff_t)index << PAGE_SHIFT; 199 bh = ext4_bread(NULL, inode, map.m_lblk, 0); 200 if (IS_ERR(bh)) { 201 err = PTR_ERR(bh); 202 bh = NULL; 203 goto errout; 204 } 205 } 206 207 if (!bh) { 208 /* corrupt size? Maybe no more blocks to read */ 209 if (ctx->pos > inode->i_blocks << 9) 210 break; 211 ctx->pos += sb->s_blocksize - offset; 212 continue; 213 } 214 215 /* Check the checksum */ 216 if (!buffer_verified(bh) && 217 !ext4_dirblock_csum_verify(inode, bh)) { 218 EXT4_ERROR_FILE(file, 0, "directory fails checksum " 219 "at offset %llu", 220 (unsigned long long)ctx->pos); 221 ctx->pos += sb->s_blocksize - offset; 222 brelse(bh); 223 bh = NULL; 224 continue; 225 } 226 set_buffer_verified(bh); 227 228 /* If the dir block has changed since the last call to 229 * readdir(2), then we might be pointing to an invalid 230 * dirent right now. Scan from the start of the block 231 * to make sure. */ 232 if (!inode_eq_iversion(inode, file->f_version)) { 233 for (i = 0; i < sb->s_blocksize && i < offset; ) { 234 de = (struct ext4_dir_entry_2 *) 235 (bh->b_data + i); 236 /* It's too expensive to do a full 237 * dirent test each time round this 238 * loop, but we do have to test at 239 * least that it is non-zero. A 240 * failure will be detected in the 241 * dirent test below. */ 242 if (ext4_rec_len_from_disk(de->rec_len, 243 sb->s_blocksize) < ext4_dir_rec_len(1, 244 inode)) 245 break; 246 i += ext4_rec_len_from_disk(de->rec_len, 247 sb->s_blocksize); 248 } 249 offset = i; 250 ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1)) 251 | offset; 252 file->f_version = inode_query_iversion(inode); 253 } 254 255 while (ctx->pos < inode->i_size 256 && offset < sb->s_blocksize) { 257 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset); 258 if (ext4_check_dir_entry(inode, file, de, bh, 259 bh->b_data, bh->b_size, 260 offset)) { 261 /* 262 * On error, skip to the next block 263 */ 264 ctx->pos = (ctx->pos | 265 (sb->s_blocksize - 1)) + 1; 266 break; 267 } 268 offset += ext4_rec_len_from_disk(de->rec_len, 269 sb->s_blocksize); 270 if (le32_to_cpu(de->inode)) { 271 if (!IS_ENCRYPTED(inode)) { 272 if (!dir_emit(ctx, de->name, 273 de->name_len, 274 le32_to_cpu(de->inode), 275 get_dtype(sb, de->file_type))) 276 goto done; 277 } else { 278 int save_len = fstr.len; 279 struct fscrypt_str de_name = 280 FSTR_INIT(de->name, 281 de->name_len); 282 283 /* Directory is encrypted */ 284 err = fscrypt_fname_disk_to_usr(inode, 285 EXT4_DIRENT_HASH(de), 286 EXT4_DIRENT_MINOR_HASH(de), 287 &de_name, &fstr); 288 de_name = fstr; 289 fstr.len = save_len; 290 if (err) 291 goto errout; 292 if (!dir_emit(ctx, 293 de_name.name, de_name.len, 294 le32_to_cpu(de->inode), 295 get_dtype(sb, de->file_type))) 296 goto done; 297 } 298 } 299 ctx->pos += ext4_rec_len_from_disk(de->rec_len, 300 sb->s_blocksize); 301 } 302 if ((ctx->pos < inode->i_size) && !dir_relax_shared(inode)) 303 goto done; 304 brelse(bh); 305 bh = NULL; 306 } 307 done: 308 err = 0; 309 errout: 310 fscrypt_fname_free_buffer(&fstr); 311 brelse(bh); 312 return err; 313 } 314 315 static inline int is_32bit_api(void) 316 { 317 #ifdef CONFIG_COMPAT 318 return in_compat_syscall(); 319 #else 320 return (BITS_PER_LONG == 32); 321 #endif 322 } 323 324 /* 325 * These functions convert from the major/minor hash to an f_pos 326 * value for dx directories 327 * 328 * Upper layer (for example NFS) should specify FMODE_32BITHASH or 329 * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted 330 * directly on both 32-bit and 64-bit nodes, under such case, neither 331 * FMODE_32BITHASH nor FMODE_64BITHASH is specified. 332 */ 333 static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor) 334 { 335 if ((filp->f_mode & FMODE_32BITHASH) || 336 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 337 return major >> 1; 338 else 339 return ((__u64)(major >> 1) << 32) | (__u64)minor; 340 } 341 342 static inline __u32 pos2maj_hash(struct file *filp, loff_t pos) 343 { 344 if ((filp->f_mode & FMODE_32BITHASH) || 345 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 346 return (pos << 1) & 0xffffffff; 347 else 348 return ((pos >> 32) << 1) & 0xffffffff; 349 } 350 351 static inline __u32 pos2min_hash(struct file *filp, loff_t pos) 352 { 353 if ((filp->f_mode & FMODE_32BITHASH) || 354 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 355 return 0; 356 else 357 return pos & 0xffffffff; 358 } 359 360 /* 361 * Return 32- or 64-bit end-of-file for dx directories 362 */ 363 static inline loff_t ext4_get_htree_eof(struct file *filp) 364 { 365 if ((filp->f_mode & FMODE_32BITHASH) || 366 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 367 return EXT4_HTREE_EOF_32BIT; 368 else 369 return EXT4_HTREE_EOF_64BIT; 370 } 371 372 373 /* 374 * ext4_dir_llseek() calls generic_file_llseek_size to handle htree 375 * directories, where the "offset" is in terms of the filename hash 376 * value instead of the byte offset. 377 * 378 * Because we may return a 64-bit hash that is well beyond offset limits, 379 * we need to pass the max hash as the maximum allowable offset in 380 * the htree directory case. 381 * 382 * For non-htree, ext4_llseek already chooses the proper max offset. 383 */ 384 static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence) 385 { 386 struct inode *inode = file->f_mapping->host; 387 int dx_dir = is_dx_dir(inode); 388 loff_t ret, htree_max = ext4_get_htree_eof(file); 389 390 if (likely(dx_dir)) 391 ret = generic_file_llseek_size(file, offset, whence, 392 htree_max, htree_max); 393 else 394 ret = ext4_llseek(file, offset, whence); 395 file->f_version = inode_peek_iversion(inode) - 1; 396 return ret; 397 } 398 399 /* 400 * This structure holds the nodes of the red-black tree used to store 401 * the directory entry in hash order. 402 */ 403 struct fname { 404 __u32 hash; 405 __u32 minor_hash; 406 struct rb_node rb_hash; 407 struct fname *next; 408 __u32 inode; 409 __u8 name_len; 410 __u8 file_type; 411 char name[]; 412 }; 413 414 /* 415 * This function implements a non-recursive way of freeing all of the 416 * nodes in the red-black tree. 417 */ 418 static void free_rb_tree_fname(struct rb_root *root) 419 { 420 struct fname *fname, *next; 421 422 rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash) 423 while (fname) { 424 struct fname *old = fname; 425 fname = fname->next; 426 kfree(old); 427 } 428 429 *root = RB_ROOT; 430 } 431 432 433 static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp, 434 loff_t pos) 435 { 436 struct dir_private_info *p; 437 438 p = kzalloc(sizeof(*p), GFP_KERNEL); 439 if (!p) 440 return NULL; 441 p->curr_hash = pos2maj_hash(filp, pos); 442 p->curr_minor_hash = pos2min_hash(filp, pos); 443 return p; 444 } 445 446 void ext4_htree_free_dir_info(struct dir_private_info *p) 447 { 448 free_rb_tree_fname(&p->root); 449 kfree(p); 450 } 451 452 /* 453 * Given a directory entry, enter it into the fname rb tree. 454 * 455 * When filename encryption is enabled, the dirent will hold the 456 * encrypted filename, while the htree will hold decrypted filename. 457 * The decrypted filename is passed in via ent_name. parameter. 458 */ 459 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash, 460 __u32 minor_hash, 461 struct ext4_dir_entry_2 *dirent, 462 struct fscrypt_str *ent_name) 463 { 464 struct rb_node **p, *parent = NULL; 465 struct fname *fname, *new_fn; 466 struct dir_private_info *info; 467 int len; 468 469 info = dir_file->private_data; 470 p = &info->root.rb_node; 471 472 /* Create and allocate the fname structure */ 473 len = sizeof(struct fname) + ent_name->len + 1; 474 new_fn = kzalloc(len, GFP_KERNEL); 475 if (!new_fn) 476 return -ENOMEM; 477 new_fn->hash = hash; 478 new_fn->minor_hash = minor_hash; 479 new_fn->inode = le32_to_cpu(dirent->inode); 480 new_fn->name_len = ent_name->len; 481 new_fn->file_type = dirent->file_type; 482 memcpy(new_fn->name, ent_name->name, ent_name->len); 483 484 while (*p) { 485 parent = *p; 486 fname = rb_entry(parent, struct fname, rb_hash); 487 488 /* 489 * If the hash and minor hash match up, then we put 490 * them on a linked list. This rarely happens... 491 */ 492 if ((new_fn->hash == fname->hash) && 493 (new_fn->minor_hash == fname->minor_hash)) { 494 new_fn->next = fname->next; 495 fname->next = new_fn; 496 return 0; 497 } 498 499 if (new_fn->hash < fname->hash) 500 p = &(*p)->rb_left; 501 else if (new_fn->hash > fname->hash) 502 p = &(*p)->rb_right; 503 else if (new_fn->minor_hash < fname->minor_hash) 504 p = &(*p)->rb_left; 505 else /* if (new_fn->minor_hash > fname->minor_hash) */ 506 p = &(*p)->rb_right; 507 } 508 509 rb_link_node(&new_fn->rb_hash, parent, p); 510 rb_insert_color(&new_fn->rb_hash, &info->root); 511 return 0; 512 } 513 514 515 516 /* 517 * This is a helper function for ext4_dx_readdir. It calls filldir 518 * for all entries on the fname linked list. (Normally there is only 519 * one entry on the linked list, unless there are 62 bit hash collisions.) 520 */ 521 static int call_filldir(struct file *file, struct dir_context *ctx, 522 struct fname *fname) 523 { 524 struct dir_private_info *info = file->private_data; 525 struct inode *inode = file_inode(file); 526 struct super_block *sb = inode->i_sb; 527 528 if (!fname) { 529 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: " 530 "called with null fname?!?", __func__, __LINE__, 531 inode->i_ino, current->comm); 532 return 0; 533 } 534 ctx->pos = hash2pos(file, fname->hash, fname->minor_hash); 535 while (fname) { 536 if (!dir_emit(ctx, fname->name, 537 fname->name_len, 538 fname->inode, 539 get_dtype(sb, fname->file_type))) { 540 info->extra_fname = fname; 541 return 1; 542 } 543 fname = fname->next; 544 } 545 return 0; 546 } 547 548 static int ext4_dx_readdir(struct file *file, struct dir_context *ctx) 549 { 550 struct dir_private_info *info = file->private_data; 551 struct inode *inode = file_inode(file); 552 struct fname *fname; 553 int ret = 0; 554 555 if (!info) { 556 info = ext4_htree_create_dir_info(file, ctx->pos); 557 if (!info) 558 return -ENOMEM; 559 file->private_data = info; 560 } 561 562 if (ctx->pos == ext4_get_htree_eof(file)) 563 return 0; /* EOF */ 564 565 /* Some one has messed with f_pos; reset the world */ 566 if (info->last_pos != ctx->pos) { 567 free_rb_tree_fname(&info->root); 568 info->curr_node = NULL; 569 info->extra_fname = NULL; 570 info->curr_hash = pos2maj_hash(file, ctx->pos); 571 info->curr_minor_hash = pos2min_hash(file, ctx->pos); 572 } 573 574 /* 575 * If there are any leftover names on the hash collision 576 * chain, return them first. 577 */ 578 if (info->extra_fname) { 579 if (call_filldir(file, ctx, info->extra_fname)) 580 goto finished; 581 info->extra_fname = NULL; 582 goto next_node; 583 } else if (!info->curr_node) 584 info->curr_node = rb_first(&info->root); 585 586 while (1) { 587 /* 588 * Fill the rbtree if we have no more entries, 589 * or the inode has changed since we last read in the 590 * cached entries. 591 */ 592 if ((!info->curr_node) || 593 !inode_eq_iversion(inode, file->f_version)) { 594 info->curr_node = NULL; 595 free_rb_tree_fname(&info->root); 596 file->f_version = inode_query_iversion(inode); 597 ret = ext4_htree_fill_tree(file, info->curr_hash, 598 info->curr_minor_hash, 599 &info->next_hash); 600 if (ret < 0) 601 goto finished; 602 if (ret == 0) { 603 ctx->pos = ext4_get_htree_eof(file); 604 break; 605 } 606 info->curr_node = rb_first(&info->root); 607 } 608 609 fname = rb_entry(info->curr_node, struct fname, rb_hash); 610 info->curr_hash = fname->hash; 611 info->curr_minor_hash = fname->minor_hash; 612 if (call_filldir(file, ctx, fname)) 613 break; 614 next_node: 615 info->curr_node = rb_next(info->curr_node); 616 if (info->curr_node) { 617 fname = rb_entry(info->curr_node, struct fname, 618 rb_hash); 619 info->curr_hash = fname->hash; 620 info->curr_minor_hash = fname->minor_hash; 621 } else { 622 if (info->next_hash == ~0) { 623 ctx->pos = ext4_get_htree_eof(file); 624 break; 625 } 626 info->curr_hash = info->next_hash; 627 info->curr_minor_hash = 0; 628 } 629 } 630 finished: 631 info->last_pos = ctx->pos; 632 return ret < 0 ? ret : 0; 633 } 634 635 static int ext4_release_dir(struct inode *inode, struct file *filp) 636 { 637 if (filp->private_data) 638 ext4_htree_free_dir_info(filp->private_data); 639 640 return 0; 641 } 642 643 int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf, 644 int buf_size) 645 { 646 struct ext4_dir_entry_2 *de; 647 int rlen; 648 unsigned int offset = 0; 649 char *top; 650 651 de = buf; 652 top = buf + buf_size; 653 while ((char *) de < top) { 654 if (ext4_check_dir_entry(dir, NULL, de, bh, 655 buf, buf_size, offset)) 656 return -EFSCORRUPTED; 657 rlen = ext4_rec_len_from_disk(de->rec_len, buf_size); 658 de = (struct ext4_dir_entry_2 *)((char *)de + rlen); 659 offset += rlen; 660 } 661 if ((char *) de > top) 662 return -EFSCORRUPTED; 663 664 return 0; 665 } 666 667 const struct file_operations ext4_dir_operations = { 668 .llseek = ext4_dir_llseek, 669 .read = generic_read_dir, 670 .iterate_shared = ext4_readdir, 671 .unlocked_ioctl = ext4_ioctl, 672 #ifdef CONFIG_COMPAT 673 .compat_ioctl = ext4_compat_ioctl, 674 #endif 675 .fsync = ext4_sync_file, 676 .release = ext4_release_dir, 677 }; 678