1 /* 2 * linux/fs/ext4/dir.c 3 * 4 * Copyright (C) 1992, 1993, 1994, 1995 5 * Remy Card (card@masi.ibp.fr) 6 * Laboratoire MASI - Institut Blaise Pascal 7 * Universite Pierre et Marie Curie (Paris VI) 8 * 9 * from 10 * 11 * linux/fs/minix/dir.c 12 * 13 * Copyright (C) 1991, 1992 Linus Torvalds 14 * 15 * ext4 directory handling functions 16 * 17 * Big-endian to little-endian byte-swapping/bitmaps by 18 * David S. Miller (davem@caip.rutgers.edu), 1995 19 * 20 * Hash Tree Directory indexing (c) 2001 Daniel Phillips 21 * 22 */ 23 24 #include <linux/fs.h> 25 #include <linux/buffer_head.h> 26 #include <linux/slab.h> 27 #include "ext4.h" 28 #include "xattr.h" 29 30 static int ext4_dx_readdir(struct file *, struct dir_context *); 31 32 /** 33 * Check if the given dir-inode refers to an htree-indexed directory 34 * (or a directory which could potentially get converted to use htree 35 * indexing). 36 * 37 * Return 1 if it is a dx dir, 0 if not 38 */ 39 static int is_dx_dir(struct inode *inode) 40 { 41 struct super_block *sb = inode->i_sb; 42 43 if (ext4_has_feature_dir_index(inode->i_sb) && 44 ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) || 45 ((inode->i_size >> sb->s_blocksize_bits) == 1) || 46 ext4_has_inline_data(inode))) 47 return 1; 48 49 return 0; 50 } 51 52 /* 53 * Return 0 if the directory entry is OK, and 1 if there is a problem 54 * 55 * Note: this is the opposite of what ext2 and ext3 historically returned... 56 * 57 * bh passed here can be an inode block or a dir data block, depending 58 * on the inode inline data flag. 59 */ 60 int __ext4_check_dir_entry(const char *function, unsigned int line, 61 struct inode *dir, struct file *filp, 62 struct ext4_dir_entry_2 *de, 63 struct buffer_head *bh, char *buf, int size, 64 unsigned int offset) 65 { 66 const char *error_msg = NULL; 67 const int rlen = ext4_rec_len_from_disk(de->rec_len, 68 dir->i_sb->s_blocksize); 69 70 if (unlikely(rlen < EXT4_DIR_REC_LEN(1))) 71 error_msg = "rec_len is smaller than minimal"; 72 else if (unlikely(rlen % 4 != 0)) 73 error_msg = "rec_len % 4 != 0"; 74 else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len))) 75 error_msg = "rec_len is too small for name_len"; 76 else if (unlikely(((char *) de - buf) + rlen > size)) 77 error_msg = "directory entry across range"; 78 else if (unlikely(le32_to_cpu(de->inode) > 79 le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count))) 80 error_msg = "inode out of bounds"; 81 else 82 return 0; 83 84 if (filp) 85 ext4_error_file(filp, function, line, bh->b_blocknr, 86 "bad entry in directory: %s - offset=%u(%u), " 87 "inode=%u, rec_len=%d, name_len=%d", 88 error_msg, (unsigned) (offset % size), 89 offset, le32_to_cpu(de->inode), 90 rlen, de->name_len); 91 else 92 ext4_error_inode(dir, function, line, bh->b_blocknr, 93 "bad entry in directory: %s - offset=%u(%u), " 94 "inode=%u, rec_len=%d, name_len=%d", 95 error_msg, (unsigned) (offset % size), 96 offset, le32_to_cpu(de->inode), 97 rlen, de->name_len); 98 99 return 1; 100 } 101 102 static int ext4_readdir(struct file *file, struct dir_context *ctx) 103 { 104 unsigned int offset; 105 int i; 106 struct ext4_dir_entry_2 *de; 107 int err; 108 struct inode *inode = file_inode(file); 109 struct super_block *sb = inode->i_sb; 110 struct buffer_head *bh = NULL; 111 int dir_has_error = 0; 112 struct ext4_str fname_crypto_str = {.name = NULL, .len = 0}; 113 114 if (ext4_encrypted_inode(inode)) { 115 err = ext4_get_encryption_info(inode); 116 if (err && err != -ENOKEY) 117 return err; 118 } 119 120 if (is_dx_dir(inode)) { 121 err = ext4_dx_readdir(file, ctx); 122 if (err != ERR_BAD_DX_DIR) { 123 return err; 124 } 125 /* 126 * We don't set the inode dirty flag since it's not 127 * critical that it get flushed back to the disk. 128 */ 129 ext4_clear_inode_flag(file_inode(file), 130 EXT4_INODE_INDEX); 131 } 132 133 if (ext4_has_inline_data(inode)) { 134 int has_inline_data = 1; 135 err = ext4_read_inline_dir(file, ctx, 136 &has_inline_data); 137 if (has_inline_data) 138 return err; 139 } 140 141 if (ext4_encrypted_inode(inode)) { 142 err = ext4_fname_crypto_alloc_buffer(inode, EXT4_NAME_LEN, 143 &fname_crypto_str); 144 if (err < 0) 145 return err; 146 } 147 148 offset = ctx->pos & (sb->s_blocksize - 1); 149 150 while (ctx->pos < inode->i_size) { 151 struct ext4_map_blocks map; 152 153 if (fatal_signal_pending(current)) { 154 err = -ERESTARTSYS; 155 goto errout; 156 } 157 cond_resched(); 158 map.m_lblk = ctx->pos >> EXT4_BLOCK_SIZE_BITS(sb); 159 map.m_len = 1; 160 err = ext4_map_blocks(NULL, inode, &map, 0); 161 if (err > 0) { 162 pgoff_t index = map.m_pblk >> 163 (PAGE_SHIFT - inode->i_blkbits); 164 if (!ra_has_index(&file->f_ra, index)) 165 page_cache_sync_readahead( 166 sb->s_bdev->bd_inode->i_mapping, 167 &file->f_ra, file, 168 index, 1); 169 file->f_ra.prev_pos = (loff_t)index << PAGE_SHIFT; 170 bh = ext4_bread(NULL, inode, map.m_lblk, 0); 171 if (IS_ERR(bh)) { 172 err = PTR_ERR(bh); 173 bh = NULL; 174 goto errout; 175 } 176 } 177 178 if (!bh) { 179 if (!dir_has_error) { 180 EXT4_ERROR_FILE(file, 0, 181 "directory contains a " 182 "hole at offset %llu", 183 (unsigned long long) ctx->pos); 184 dir_has_error = 1; 185 } 186 /* corrupt size? Maybe no more blocks to read */ 187 if (ctx->pos > inode->i_blocks << 9) 188 break; 189 ctx->pos += sb->s_blocksize - offset; 190 continue; 191 } 192 193 /* Check the checksum */ 194 if (!buffer_verified(bh) && 195 !ext4_dirent_csum_verify(inode, 196 (struct ext4_dir_entry *)bh->b_data)) { 197 EXT4_ERROR_FILE(file, 0, "directory fails checksum " 198 "at offset %llu", 199 (unsigned long long)ctx->pos); 200 ctx->pos += sb->s_blocksize - offset; 201 brelse(bh); 202 bh = NULL; 203 continue; 204 } 205 set_buffer_verified(bh); 206 207 /* If the dir block has changed since the last call to 208 * readdir(2), then we might be pointing to an invalid 209 * dirent right now. Scan from the start of the block 210 * to make sure. */ 211 if (file->f_version != inode->i_version) { 212 for (i = 0; i < sb->s_blocksize && i < offset; ) { 213 de = (struct ext4_dir_entry_2 *) 214 (bh->b_data + i); 215 /* It's too expensive to do a full 216 * dirent test each time round this 217 * loop, but we do have to test at 218 * least that it is non-zero. A 219 * failure will be detected in the 220 * dirent test below. */ 221 if (ext4_rec_len_from_disk(de->rec_len, 222 sb->s_blocksize) < EXT4_DIR_REC_LEN(1)) 223 break; 224 i += ext4_rec_len_from_disk(de->rec_len, 225 sb->s_blocksize); 226 } 227 offset = i; 228 ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1)) 229 | offset; 230 file->f_version = inode->i_version; 231 } 232 233 while (ctx->pos < inode->i_size 234 && offset < sb->s_blocksize) { 235 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset); 236 if (ext4_check_dir_entry(inode, file, de, bh, 237 bh->b_data, bh->b_size, 238 offset)) { 239 /* 240 * On error, skip to the next block 241 */ 242 ctx->pos = (ctx->pos | 243 (sb->s_blocksize - 1)) + 1; 244 break; 245 } 246 offset += ext4_rec_len_from_disk(de->rec_len, 247 sb->s_blocksize); 248 if (le32_to_cpu(de->inode)) { 249 if (!ext4_encrypted_inode(inode)) { 250 if (!dir_emit(ctx, de->name, 251 de->name_len, 252 le32_to_cpu(de->inode), 253 get_dtype(sb, de->file_type))) 254 goto done; 255 } else { 256 int save_len = fname_crypto_str.len; 257 258 /* Directory is encrypted */ 259 err = ext4_fname_disk_to_usr(inode, 260 NULL, de, &fname_crypto_str); 261 fname_crypto_str.len = save_len; 262 if (err < 0) 263 goto errout; 264 if (!dir_emit(ctx, 265 fname_crypto_str.name, err, 266 le32_to_cpu(de->inode), 267 get_dtype(sb, de->file_type))) 268 goto done; 269 } 270 } 271 ctx->pos += ext4_rec_len_from_disk(de->rec_len, 272 sb->s_blocksize); 273 } 274 if ((ctx->pos < inode->i_size) && !dir_relax_shared(inode)) 275 goto done; 276 brelse(bh); 277 bh = NULL; 278 offset = 0; 279 } 280 done: 281 err = 0; 282 errout: 283 #ifdef CONFIG_EXT4_FS_ENCRYPTION 284 ext4_fname_crypto_free_buffer(&fname_crypto_str); 285 #endif 286 brelse(bh); 287 return err; 288 } 289 290 static inline int is_32bit_api(void) 291 { 292 #ifdef CONFIG_COMPAT 293 return in_compat_syscall(); 294 #else 295 return (BITS_PER_LONG == 32); 296 #endif 297 } 298 299 /* 300 * These functions convert from the major/minor hash to an f_pos 301 * value for dx directories 302 * 303 * Upper layer (for example NFS) should specify FMODE_32BITHASH or 304 * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted 305 * directly on both 32-bit and 64-bit nodes, under such case, neither 306 * FMODE_32BITHASH nor FMODE_64BITHASH is specified. 307 */ 308 static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor) 309 { 310 if ((filp->f_mode & FMODE_32BITHASH) || 311 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 312 return major >> 1; 313 else 314 return ((__u64)(major >> 1) << 32) | (__u64)minor; 315 } 316 317 static inline __u32 pos2maj_hash(struct file *filp, loff_t pos) 318 { 319 if ((filp->f_mode & FMODE_32BITHASH) || 320 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 321 return (pos << 1) & 0xffffffff; 322 else 323 return ((pos >> 32) << 1) & 0xffffffff; 324 } 325 326 static inline __u32 pos2min_hash(struct file *filp, loff_t pos) 327 { 328 if ((filp->f_mode & FMODE_32BITHASH) || 329 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 330 return 0; 331 else 332 return pos & 0xffffffff; 333 } 334 335 /* 336 * Return 32- or 64-bit end-of-file for dx directories 337 */ 338 static inline loff_t ext4_get_htree_eof(struct file *filp) 339 { 340 if ((filp->f_mode & FMODE_32BITHASH) || 341 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 342 return EXT4_HTREE_EOF_32BIT; 343 else 344 return EXT4_HTREE_EOF_64BIT; 345 } 346 347 348 /* 349 * ext4_dir_llseek() calls generic_file_llseek_size to handle htree 350 * directories, where the "offset" is in terms of the filename hash 351 * value instead of the byte offset. 352 * 353 * Because we may return a 64-bit hash that is well beyond offset limits, 354 * we need to pass the max hash as the maximum allowable offset in 355 * the htree directory case. 356 * 357 * For non-htree, ext4_llseek already chooses the proper max offset. 358 */ 359 static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence) 360 { 361 struct inode *inode = file->f_mapping->host; 362 int dx_dir = is_dx_dir(inode); 363 loff_t htree_max = ext4_get_htree_eof(file); 364 365 if (likely(dx_dir)) 366 return generic_file_llseek_size(file, offset, whence, 367 htree_max, htree_max); 368 else 369 return ext4_llseek(file, offset, whence); 370 } 371 372 /* 373 * This structure holds the nodes of the red-black tree used to store 374 * the directory entry in hash order. 375 */ 376 struct fname { 377 __u32 hash; 378 __u32 minor_hash; 379 struct rb_node rb_hash; 380 struct fname *next; 381 __u32 inode; 382 __u8 name_len; 383 __u8 file_type; 384 char name[0]; 385 }; 386 387 /* 388 * This functoin implements a non-recursive way of freeing all of the 389 * nodes in the red-black tree. 390 */ 391 static void free_rb_tree_fname(struct rb_root *root) 392 { 393 struct fname *fname, *next; 394 395 rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash) 396 while (fname) { 397 struct fname *old = fname; 398 fname = fname->next; 399 kfree(old); 400 } 401 402 *root = RB_ROOT; 403 } 404 405 406 static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp, 407 loff_t pos) 408 { 409 struct dir_private_info *p; 410 411 p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL); 412 if (!p) 413 return NULL; 414 p->curr_hash = pos2maj_hash(filp, pos); 415 p->curr_minor_hash = pos2min_hash(filp, pos); 416 return p; 417 } 418 419 void ext4_htree_free_dir_info(struct dir_private_info *p) 420 { 421 free_rb_tree_fname(&p->root); 422 kfree(p); 423 } 424 425 /* 426 * Given a directory entry, enter it into the fname rb tree. 427 * 428 * When filename encryption is enabled, the dirent will hold the 429 * encrypted filename, while the htree will hold decrypted filename. 430 * The decrypted filename is passed in via ent_name. parameter. 431 */ 432 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash, 433 __u32 minor_hash, 434 struct ext4_dir_entry_2 *dirent, 435 struct ext4_str *ent_name) 436 { 437 struct rb_node **p, *parent = NULL; 438 struct fname *fname, *new_fn; 439 struct dir_private_info *info; 440 int len; 441 442 info = dir_file->private_data; 443 p = &info->root.rb_node; 444 445 /* Create and allocate the fname structure */ 446 len = sizeof(struct fname) + ent_name->len + 1; 447 new_fn = kzalloc(len, GFP_KERNEL); 448 if (!new_fn) 449 return -ENOMEM; 450 new_fn->hash = hash; 451 new_fn->minor_hash = minor_hash; 452 new_fn->inode = le32_to_cpu(dirent->inode); 453 new_fn->name_len = ent_name->len; 454 new_fn->file_type = dirent->file_type; 455 memcpy(new_fn->name, ent_name->name, ent_name->len); 456 new_fn->name[ent_name->len] = 0; 457 458 while (*p) { 459 parent = *p; 460 fname = rb_entry(parent, struct fname, rb_hash); 461 462 /* 463 * If the hash and minor hash match up, then we put 464 * them on a linked list. This rarely happens... 465 */ 466 if ((new_fn->hash == fname->hash) && 467 (new_fn->minor_hash == fname->minor_hash)) { 468 new_fn->next = fname->next; 469 fname->next = new_fn; 470 return 0; 471 } 472 473 if (new_fn->hash < fname->hash) 474 p = &(*p)->rb_left; 475 else if (new_fn->hash > fname->hash) 476 p = &(*p)->rb_right; 477 else if (new_fn->minor_hash < fname->minor_hash) 478 p = &(*p)->rb_left; 479 else /* if (new_fn->minor_hash > fname->minor_hash) */ 480 p = &(*p)->rb_right; 481 } 482 483 rb_link_node(&new_fn->rb_hash, parent, p); 484 rb_insert_color(&new_fn->rb_hash, &info->root); 485 return 0; 486 } 487 488 489 490 /* 491 * This is a helper function for ext4_dx_readdir. It calls filldir 492 * for all entres on the fname linked list. (Normally there is only 493 * one entry on the linked list, unless there are 62 bit hash collisions.) 494 */ 495 static int call_filldir(struct file *file, struct dir_context *ctx, 496 struct fname *fname) 497 { 498 struct dir_private_info *info = file->private_data; 499 struct inode *inode = file_inode(file); 500 struct super_block *sb = inode->i_sb; 501 502 if (!fname) { 503 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: " 504 "called with null fname?!?", __func__, __LINE__, 505 inode->i_ino, current->comm); 506 return 0; 507 } 508 ctx->pos = hash2pos(file, fname->hash, fname->minor_hash); 509 while (fname) { 510 if (!dir_emit(ctx, fname->name, 511 fname->name_len, 512 fname->inode, 513 get_dtype(sb, fname->file_type))) { 514 info->extra_fname = fname; 515 return 1; 516 } 517 fname = fname->next; 518 } 519 return 0; 520 } 521 522 static int ext4_dx_readdir(struct file *file, struct dir_context *ctx) 523 { 524 struct dir_private_info *info = file->private_data; 525 struct inode *inode = file_inode(file); 526 struct fname *fname; 527 int ret; 528 529 if (!info) { 530 info = ext4_htree_create_dir_info(file, ctx->pos); 531 if (!info) 532 return -ENOMEM; 533 file->private_data = info; 534 } 535 536 if (ctx->pos == ext4_get_htree_eof(file)) 537 return 0; /* EOF */ 538 539 /* Some one has messed with f_pos; reset the world */ 540 if (info->last_pos != ctx->pos) { 541 free_rb_tree_fname(&info->root); 542 info->curr_node = NULL; 543 info->extra_fname = NULL; 544 info->curr_hash = pos2maj_hash(file, ctx->pos); 545 info->curr_minor_hash = pos2min_hash(file, ctx->pos); 546 } 547 548 /* 549 * If there are any leftover names on the hash collision 550 * chain, return them first. 551 */ 552 if (info->extra_fname) { 553 if (call_filldir(file, ctx, info->extra_fname)) 554 goto finished; 555 info->extra_fname = NULL; 556 goto next_node; 557 } else if (!info->curr_node) 558 info->curr_node = rb_first(&info->root); 559 560 while (1) { 561 /* 562 * Fill the rbtree if we have no more entries, 563 * or the inode has changed since we last read in the 564 * cached entries. 565 */ 566 if ((!info->curr_node) || 567 (file->f_version != inode->i_version)) { 568 info->curr_node = NULL; 569 free_rb_tree_fname(&info->root); 570 file->f_version = inode->i_version; 571 ret = ext4_htree_fill_tree(file, info->curr_hash, 572 info->curr_minor_hash, 573 &info->next_hash); 574 if (ret < 0) 575 return ret; 576 if (ret == 0) { 577 ctx->pos = ext4_get_htree_eof(file); 578 break; 579 } 580 info->curr_node = rb_first(&info->root); 581 } 582 583 fname = rb_entry(info->curr_node, struct fname, rb_hash); 584 info->curr_hash = fname->hash; 585 info->curr_minor_hash = fname->minor_hash; 586 if (call_filldir(file, ctx, fname)) 587 break; 588 next_node: 589 info->curr_node = rb_next(info->curr_node); 590 if (info->curr_node) { 591 fname = rb_entry(info->curr_node, struct fname, 592 rb_hash); 593 info->curr_hash = fname->hash; 594 info->curr_minor_hash = fname->minor_hash; 595 } else { 596 if (info->next_hash == ~0) { 597 ctx->pos = ext4_get_htree_eof(file); 598 break; 599 } 600 info->curr_hash = info->next_hash; 601 info->curr_minor_hash = 0; 602 } 603 } 604 finished: 605 info->last_pos = ctx->pos; 606 return 0; 607 } 608 609 static int ext4_dir_open(struct inode * inode, struct file * filp) 610 { 611 if (ext4_encrypted_inode(inode)) 612 return ext4_get_encryption_info(inode) ? -EACCES : 0; 613 return 0; 614 } 615 616 static int ext4_release_dir(struct inode *inode, struct file *filp) 617 { 618 if (filp->private_data) 619 ext4_htree_free_dir_info(filp->private_data); 620 621 return 0; 622 } 623 624 int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf, 625 int buf_size) 626 { 627 struct ext4_dir_entry_2 *de; 628 int nlen, rlen; 629 unsigned int offset = 0; 630 char *top; 631 632 de = (struct ext4_dir_entry_2 *)buf; 633 top = buf + buf_size; 634 while ((char *) de < top) { 635 if (ext4_check_dir_entry(dir, NULL, de, bh, 636 buf, buf_size, offset)) 637 return -EFSCORRUPTED; 638 nlen = EXT4_DIR_REC_LEN(de->name_len); 639 rlen = ext4_rec_len_from_disk(de->rec_len, buf_size); 640 de = (struct ext4_dir_entry_2 *)((char *)de + rlen); 641 offset += rlen; 642 } 643 if ((char *) de > top) 644 return -EFSCORRUPTED; 645 646 return 0; 647 } 648 649 const struct file_operations ext4_dir_operations = { 650 .llseek = ext4_dir_llseek, 651 .read = generic_read_dir, 652 .iterate_shared = ext4_readdir, 653 .unlocked_ioctl = ext4_ioctl, 654 #ifdef CONFIG_COMPAT 655 .compat_ioctl = ext4_compat_ioctl, 656 #endif 657 .fsync = ext4_sync_file, 658 .open = ext4_dir_open, 659 .release = ext4_release_dir, 660 }; 661