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_COMPAT_FEATURE(inode->i_sb, 44 EXT4_FEATURE_COMPAT_DIR_INDEX) && 45 ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) || 46 ((inode->i_size >> sb->s_blocksize_bits) == 1) || 47 ext4_has_inline_data(inode))) 48 return 1; 49 50 return 0; 51 } 52 53 /* 54 * Return 0 if the directory entry is OK, and 1 if there is a problem 55 * 56 * Note: this is the opposite of what ext2 and ext3 historically returned... 57 * 58 * bh passed here can be an inode block or a dir data block, depending 59 * on the inode inline data flag. 60 */ 61 int __ext4_check_dir_entry(const char *function, unsigned int line, 62 struct inode *dir, struct file *filp, 63 struct ext4_dir_entry_2 *de, 64 struct buffer_head *bh, char *buf, int size, 65 unsigned int offset) 66 { 67 const char *error_msg = NULL; 68 const int rlen = ext4_rec_len_from_disk(de->rec_len, 69 dir->i_sb->s_blocksize); 70 71 if (unlikely(rlen < EXT4_DIR_REC_LEN(1))) 72 error_msg = "rec_len is smaller than minimal"; 73 else if (unlikely(rlen % 4 != 0)) 74 error_msg = "rec_len % 4 != 0"; 75 else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len))) 76 error_msg = "rec_len is too small for name_len"; 77 else if (unlikely(((char *) de - buf) + rlen > size)) 78 error_msg = "directory entry across range"; 79 else if (unlikely(le32_to_cpu(de->inode) > 80 le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count))) 81 error_msg = "inode out of bounds"; 82 else 83 return 0; 84 85 if (filp) 86 ext4_error_file(filp, function, line, bh->b_blocknr, 87 "bad entry in directory: %s - offset=%u(%u), " 88 "inode=%u, rec_len=%d, name_len=%d", 89 error_msg, (unsigned) (offset % size), 90 offset, le32_to_cpu(de->inode), 91 rlen, de->name_len); 92 else 93 ext4_error_inode(dir, function, line, bh->b_blocknr, 94 "bad entry in directory: %s - offset=%u(%u), " 95 "inode=%u, rec_len=%d, name_len=%d", 96 error_msg, (unsigned) (offset % size), 97 offset, le32_to_cpu(de->inode), 98 rlen, de->name_len); 99 100 return 1; 101 } 102 103 static int ext4_readdir(struct file *file, struct dir_context *ctx) 104 { 105 unsigned int offset; 106 int i; 107 struct ext4_dir_entry_2 *de; 108 int err; 109 struct inode *inode = file_inode(file); 110 struct super_block *sb = inode->i_sb; 111 struct buffer_head *bh = NULL; 112 int dir_has_error = 0; 113 struct ext4_str fname_crypto_str = {.name = NULL, .len = 0}; 114 115 if (is_dx_dir(inode)) { 116 err = ext4_dx_readdir(file, ctx); 117 if (err != ERR_BAD_DX_DIR) { 118 return err; 119 } 120 /* 121 * We don't set the inode dirty flag since it's not 122 * critical that it get flushed back to the disk. 123 */ 124 ext4_clear_inode_flag(file_inode(file), 125 EXT4_INODE_INDEX); 126 } 127 128 if (ext4_has_inline_data(inode)) { 129 int has_inline_data = 1; 130 err = ext4_read_inline_dir(file, ctx, 131 &has_inline_data); 132 if (has_inline_data) 133 return err; 134 } 135 136 if (ext4_encrypted_inode(inode)) { 137 err = ext4_fname_crypto_alloc_buffer(inode, EXT4_NAME_LEN, 138 &fname_crypto_str); 139 if (err < 0) 140 return err; 141 } 142 143 offset = ctx->pos & (sb->s_blocksize - 1); 144 145 while (ctx->pos < inode->i_size) { 146 struct ext4_map_blocks map; 147 148 map.m_lblk = ctx->pos >> EXT4_BLOCK_SIZE_BITS(sb); 149 map.m_len = 1; 150 err = ext4_map_blocks(NULL, inode, &map, 0); 151 if (err > 0) { 152 pgoff_t index = map.m_pblk >> 153 (PAGE_CACHE_SHIFT - inode->i_blkbits); 154 if (!ra_has_index(&file->f_ra, index)) 155 page_cache_sync_readahead( 156 sb->s_bdev->bd_inode->i_mapping, 157 &file->f_ra, file, 158 index, 1); 159 file->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; 160 bh = ext4_bread(NULL, inode, map.m_lblk, 0); 161 if (IS_ERR(bh)) 162 return PTR_ERR(bh); 163 } 164 165 if (!bh) { 166 if (!dir_has_error) { 167 EXT4_ERROR_FILE(file, 0, 168 "directory contains a " 169 "hole at offset %llu", 170 (unsigned long long) ctx->pos); 171 dir_has_error = 1; 172 } 173 /* corrupt size? Maybe no more blocks to read */ 174 if (ctx->pos > inode->i_blocks << 9) 175 break; 176 ctx->pos += sb->s_blocksize - offset; 177 continue; 178 } 179 180 /* Check the checksum */ 181 if (!buffer_verified(bh) && 182 !ext4_dirent_csum_verify(inode, 183 (struct ext4_dir_entry *)bh->b_data)) { 184 EXT4_ERROR_FILE(file, 0, "directory fails checksum " 185 "at offset %llu", 186 (unsigned long long)ctx->pos); 187 ctx->pos += sb->s_blocksize - offset; 188 brelse(bh); 189 bh = NULL; 190 continue; 191 } 192 set_buffer_verified(bh); 193 194 /* If the dir block has changed since the last call to 195 * readdir(2), then we might be pointing to an invalid 196 * dirent right now. Scan from the start of the block 197 * to make sure. */ 198 if (file->f_version != inode->i_version) { 199 for (i = 0; i < sb->s_blocksize && i < offset; ) { 200 de = (struct ext4_dir_entry_2 *) 201 (bh->b_data + i); 202 /* It's too expensive to do a full 203 * dirent test each time round this 204 * loop, but we do have to test at 205 * least that it is non-zero. A 206 * failure will be detected in the 207 * dirent test below. */ 208 if (ext4_rec_len_from_disk(de->rec_len, 209 sb->s_blocksize) < EXT4_DIR_REC_LEN(1)) 210 break; 211 i += ext4_rec_len_from_disk(de->rec_len, 212 sb->s_blocksize); 213 } 214 offset = i; 215 ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1)) 216 | offset; 217 file->f_version = inode->i_version; 218 } 219 220 while (ctx->pos < inode->i_size 221 && offset < sb->s_blocksize) { 222 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset); 223 if (ext4_check_dir_entry(inode, file, de, bh, 224 bh->b_data, bh->b_size, 225 offset)) { 226 /* 227 * On error, skip to the next block 228 */ 229 ctx->pos = (ctx->pos | 230 (sb->s_blocksize - 1)) + 1; 231 break; 232 } 233 offset += ext4_rec_len_from_disk(de->rec_len, 234 sb->s_blocksize); 235 if (le32_to_cpu(de->inode)) { 236 if (!ext4_encrypted_inode(inode)) { 237 if (!dir_emit(ctx, de->name, 238 de->name_len, 239 le32_to_cpu(de->inode), 240 get_dtype(sb, de->file_type))) 241 goto done; 242 } else { 243 int save_len = fname_crypto_str.len; 244 245 /* Directory is encrypted */ 246 err = ext4_fname_disk_to_usr(inode, 247 NULL, de, &fname_crypto_str); 248 fname_crypto_str.len = save_len; 249 if (err < 0) 250 goto errout; 251 if (!dir_emit(ctx, 252 fname_crypto_str.name, err, 253 le32_to_cpu(de->inode), 254 get_dtype(sb, de->file_type))) 255 goto done; 256 } 257 } 258 ctx->pos += ext4_rec_len_from_disk(de->rec_len, 259 sb->s_blocksize); 260 } 261 if ((ctx->pos < inode->i_size) && !dir_relax(inode)) 262 goto done; 263 brelse(bh); 264 bh = NULL; 265 offset = 0; 266 } 267 done: 268 err = 0; 269 errout: 270 #ifdef CONFIG_EXT4_FS_ENCRYPTION 271 ext4_fname_crypto_free_buffer(&fname_crypto_str); 272 #endif 273 brelse(bh); 274 return err; 275 } 276 277 static inline int is_32bit_api(void) 278 { 279 #ifdef CONFIG_COMPAT 280 return is_compat_task(); 281 #else 282 return (BITS_PER_LONG == 32); 283 #endif 284 } 285 286 /* 287 * These functions convert from the major/minor hash to an f_pos 288 * value for dx directories 289 * 290 * Upper layer (for example NFS) should specify FMODE_32BITHASH or 291 * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted 292 * directly on both 32-bit and 64-bit nodes, under such case, neither 293 * FMODE_32BITHASH nor FMODE_64BITHASH is specified. 294 */ 295 static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor) 296 { 297 if ((filp->f_mode & FMODE_32BITHASH) || 298 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 299 return major >> 1; 300 else 301 return ((__u64)(major >> 1) << 32) | (__u64)minor; 302 } 303 304 static inline __u32 pos2maj_hash(struct file *filp, loff_t pos) 305 { 306 if ((filp->f_mode & FMODE_32BITHASH) || 307 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 308 return (pos << 1) & 0xffffffff; 309 else 310 return ((pos >> 32) << 1) & 0xffffffff; 311 } 312 313 static inline __u32 pos2min_hash(struct file *filp, loff_t pos) 314 { 315 if ((filp->f_mode & FMODE_32BITHASH) || 316 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 317 return 0; 318 else 319 return pos & 0xffffffff; 320 } 321 322 /* 323 * Return 32- or 64-bit end-of-file for dx directories 324 */ 325 static inline loff_t ext4_get_htree_eof(struct file *filp) 326 { 327 if ((filp->f_mode & FMODE_32BITHASH) || 328 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 329 return EXT4_HTREE_EOF_32BIT; 330 else 331 return EXT4_HTREE_EOF_64BIT; 332 } 333 334 335 /* 336 * ext4_dir_llseek() calls generic_file_llseek_size to handle htree 337 * directories, where the "offset" is in terms of the filename hash 338 * value instead of the byte offset. 339 * 340 * Because we may return a 64-bit hash that is well beyond offset limits, 341 * we need to pass the max hash as the maximum allowable offset in 342 * the htree directory case. 343 * 344 * For non-htree, ext4_llseek already chooses the proper max offset. 345 */ 346 static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence) 347 { 348 struct inode *inode = file->f_mapping->host; 349 int dx_dir = is_dx_dir(inode); 350 loff_t htree_max = ext4_get_htree_eof(file); 351 352 if (likely(dx_dir)) 353 return generic_file_llseek_size(file, offset, whence, 354 htree_max, htree_max); 355 else 356 return ext4_llseek(file, offset, whence); 357 } 358 359 /* 360 * This structure holds the nodes of the red-black tree used to store 361 * the directory entry in hash order. 362 */ 363 struct fname { 364 __u32 hash; 365 __u32 minor_hash; 366 struct rb_node rb_hash; 367 struct fname *next; 368 __u32 inode; 369 __u8 name_len; 370 __u8 file_type; 371 char name[0]; 372 }; 373 374 /* 375 * This functoin implements a non-recursive way of freeing all of the 376 * nodes in the red-black tree. 377 */ 378 static void free_rb_tree_fname(struct rb_root *root) 379 { 380 struct fname *fname, *next; 381 382 rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash) 383 while (fname) { 384 struct fname *old = fname; 385 fname = fname->next; 386 kfree(old); 387 } 388 389 *root = RB_ROOT; 390 } 391 392 393 static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp, 394 loff_t pos) 395 { 396 struct dir_private_info *p; 397 398 p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL); 399 if (!p) 400 return NULL; 401 p->curr_hash = pos2maj_hash(filp, pos); 402 p->curr_minor_hash = pos2min_hash(filp, pos); 403 return p; 404 } 405 406 void ext4_htree_free_dir_info(struct dir_private_info *p) 407 { 408 free_rb_tree_fname(&p->root); 409 kfree(p); 410 } 411 412 /* 413 * Given a directory entry, enter it into the fname rb tree. 414 * 415 * When filename encryption is enabled, the dirent will hold the 416 * encrypted filename, while the htree will hold decrypted filename. 417 * The decrypted filename is passed in via ent_name. parameter. 418 */ 419 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash, 420 __u32 minor_hash, 421 struct ext4_dir_entry_2 *dirent, 422 struct ext4_str *ent_name) 423 { 424 struct rb_node **p, *parent = NULL; 425 struct fname *fname, *new_fn; 426 struct dir_private_info *info; 427 int len; 428 429 info = dir_file->private_data; 430 p = &info->root.rb_node; 431 432 /* Create and allocate the fname structure */ 433 len = sizeof(struct fname) + ent_name->len + 1; 434 new_fn = kzalloc(len, GFP_KERNEL); 435 if (!new_fn) 436 return -ENOMEM; 437 new_fn->hash = hash; 438 new_fn->minor_hash = minor_hash; 439 new_fn->inode = le32_to_cpu(dirent->inode); 440 new_fn->name_len = ent_name->len; 441 new_fn->file_type = dirent->file_type; 442 memcpy(new_fn->name, ent_name->name, ent_name->len); 443 new_fn->name[ent_name->len] = 0; 444 445 while (*p) { 446 parent = *p; 447 fname = rb_entry(parent, struct fname, rb_hash); 448 449 /* 450 * If the hash and minor hash match up, then we put 451 * them on a linked list. This rarely happens... 452 */ 453 if ((new_fn->hash == fname->hash) && 454 (new_fn->minor_hash == fname->minor_hash)) { 455 new_fn->next = fname->next; 456 fname->next = new_fn; 457 return 0; 458 } 459 460 if (new_fn->hash < fname->hash) 461 p = &(*p)->rb_left; 462 else if (new_fn->hash > fname->hash) 463 p = &(*p)->rb_right; 464 else if (new_fn->minor_hash < fname->minor_hash) 465 p = &(*p)->rb_left; 466 else /* if (new_fn->minor_hash > fname->minor_hash) */ 467 p = &(*p)->rb_right; 468 } 469 470 rb_link_node(&new_fn->rb_hash, parent, p); 471 rb_insert_color(&new_fn->rb_hash, &info->root); 472 return 0; 473 } 474 475 476 477 /* 478 * This is a helper function for ext4_dx_readdir. It calls filldir 479 * for all entres on the fname linked list. (Normally there is only 480 * one entry on the linked list, unless there are 62 bit hash collisions.) 481 */ 482 static int call_filldir(struct file *file, struct dir_context *ctx, 483 struct fname *fname) 484 { 485 struct dir_private_info *info = file->private_data; 486 struct inode *inode = file_inode(file); 487 struct super_block *sb = inode->i_sb; 488 489 if (!fname) { 490 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: " 491 "called with null fname?!?", __func__, __LINE__, 492 inode->i_ino, current->comm); 493 return 0; 494 } 495 ctx->pos = hash2pos(file, fname->hash, fname->minor_hash); 496 while (fname) { 497 if (!dir_emit(ctx, fname->name, 498 fname->name_len, 499 fname->inode, 500 get_dtype(sb, fname->file_type))) { 501 info->extra_fname = fname; 502 return 1; 503 } 504 fname = fname->next; 505 } 506 return 0; 507 } 508 509 static int ext4_dx_readdir(struct file *file, struct dir_context *ctx) 510 { 511 struct dir_private_info *info = file->private_data; 512 struct inode *inode = file_inode(file); 513 struct fname *fname; 514 int ret; 515 516 if (!info) { 517 info = ext4_htree_create_dir_info(file, ctx->pos); 518 if (!info) 519 return -ENOMEM; 520 file->private_data = info; 521 } 522 523 if (ctx->pos == ext4_get_htree_eof(file)) 524 return 0; /* EOF */ 525 526 /* Some one has messed with f_pos; reset the world */ 527 if (info->last_pos != ctx->pos) { 528 free_rb_tree_fname(&info->root); 529 info->curr_node = NULL; 530 info->extra_fname = NULL; 531 info->curr_hash = pos2maj_hash(file, ctx->pos); 532 info->curr_minor_hash = pos2min_hash(file, ctx->pos); 533 } 534 535 /* 536 * If there are any leftover names on the hash collision 537 * chain, return them first. 538 */ 539 if (info->extra_fname) { 540 if (call_filldir(file, ctx, info->extra_fname)) 541 goto finished; 542 info->extra_fname = NULL; 543 goto next_node; 544 } else if (!info->curr_node) 545 info->curr_node = rb_first(&info->root); 546 547 while (1) { 548 /* 549 * Fill the rbtree if we have no more entries, 550 * or the inode has changed since we last read in the 551 * cached entries. 552 */ 553 if ((!info->curr_node) || 554 (file->f_version != inode->i_version)) { 555 info->curr_node = NULL; 556 free_rb_tree_fname(&info->root); 557 file->f_version = inode->i_version; 558 ret = ext4_htree_fill_tree(file, info->curr_hash, 559 info->curr_minor_hash, 560 &info->next_hash); 561 if (ret < 0) 562 return ret; 563 if (ret == 0) { 564 ctx->pos = ext4_get_htree_eof(file); 565 break; 566 } 567 info->curr_node = rb_first(&info->root); 568 } 569 570 fname = rb_entry(info->curr_node, struct fname, rb_hash); 571 info->curr_hash = fname->hash; 572 info->curr_minor_hash = fname->minor_hash; 573 if (call_filldir(file, ctx, fname)) 574 break; 575 next_node: 576 info->curr_node = rb_next(info->curr_node); 577 if (info->curr_node) { 578 fname = rb_entry(info->curr_node, struct fname, 579 rb_hash); 580 info->curr_hash = fname->hash; 581 info->curr_minor_hash = fname->minor_hash; 582 } else { 583 if (info->next_hash == ~0) { 584 ctx->pos = ext4_get_htree_eof(file); 585 break; 586 } 587 info->curr_hash = info->next_hash; 588 info->curr_minor_hash = 0; 589 } 590 } 591 finished: 592 info->last_pos = ctx->pos; 593 return 0; 594 } 595 596 static int ext4_dir_open(struct inode * inode, struct file * filp) 597 { 598 if (ext4_encrypted_inode(inode)) 599 return ext4_get_encryption_info(inode) ? -EACCES : 0; 600 return 0; 601 } 602 603 static int ext4_release_dir(struct inode *inode, struct file *filp) 604 { 605 if (filp->private_data) 606 ext4_htree_free_dir_info(filp->private_data); 607 608 return 0; 609 } 610 611 int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf, 612 int buf_size) 613 { 614 struct ext4_dir_entry_2 *de; 615 int nlen, rlen; 616 unsigned int offset = 0; 617 char *top; 618 619 de = (struct ext4_dir_entry_2 *)buf; 620 top = buf + buf_size; 621 while ((char *) de < top) { 622 if (ext4_check_dir_entry(dir, NULL, de, bh, 623 buf, buf_size, offset)) 624 return -EIO; 625 nlen = EXT4_DIR_REC_LEN(de->name_len); 626 rlen = ext4_rec_len_from_disk(de->rec_len, buf_size); 627 de = (struct ext4_dir_entry_2 *)((char *)de + rlen); 628 offset += rlen; 629 } 630 if ((char *) de > top) 631 return -EIO; 632 633 return 0; 634 } 635 636 const struct file_operations ext4_dir_operations = { 637 .llseek = ext4_dir_llseek, 638 .read = generic_read_dir, 639 .iterate = ext4_readdir, 640 .unlocked_ioctl = ext4_ioctl, 641 #ifdef CONFIG_COMPAT 642 .compat_ioctl = ext4_compat_ioctl, 643 #endif 644 .fsync = ext4_sync_file, 645 .open = ext4_dir_open, 646 .release = ext4_release_dir, 647 }; 648