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_fname_crypto_ctx *enc_ctx = NULL; 114 struct ext4_str fname_crypto_str = {.name = NULL, .len = 0}; 115 116 if (is_dx_dir(inode)) { 117 err = ext4_dx_readdir(file, ctx); 118 if (err != ERR_BAD_DX_DIR) { 119 return err; 120 } 121 /* 122 * We don't set the inode dirty flag since it's not 123 * critical that it get flushed back to the disk. 124 */ 125 ext4_clear_inode_flag(file_inode(file), 126 EXT4_INODE_INDEX); 127 } 128 129 if (ext4_has_inline_data(inode)) { 130 int has_inline_data = 1; 131 err = ext4_read_inline_dir(file, ctx, 132 &has_inline_data); 133 if (has_inline_data) 134 return err; 135 } 136 137 enc_ctx = ext4_get_fname_crypto_ctx(inode, EXT4_NAME_LEN); 138 if (IS_ERR(enc_ctx)) 139 return PTR_ERR(enc_ctx); 140 if (enc_ctx) { 141 err = ext4_fname_crypto_alloc_buffer(enc_ctx, EXT4_NAME_LEN, 142 &fname_crypto_str); 143 if (err < 0) { 144 ext4_put_fname_crypto_ctx(&enc_ctx); 145 return err; 146 } 147 } 148 149 offset = ctx->pos & (sb->s_blocksize - 1); 150 151 while (ctx->pos < inode->i_size) { 152 struct ext4_map_blocks map; 153 154 map.m_lblk = ctx->pos >> EXT4_BLOCK_SIZE_BITS(sb); 155 map.m_len = 1; 156 err = ext4_map_blocks(NULL, inode, &map, 0); 157 if (err > 0) { 158 pgoff_t index = map.m_pblk >> 159 (PAGE_CACHE_SHIFT - inode->i_blkbits); 160 if (!ra_has_index(&file->f_ra, index)) 161 page_cache_sync_readahead( 162 sb->s_bdev->bd_inode->i_mapping, 163 &file->f_ra, file, 164 index, 1); 165 file->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; 166 bh = ext4_bread(NULL, inode, map.m_lblk, 0); 167 if (IS_ERR(bh)) 168 return PTR_ERR(bh); 169 } 170 171 if (!bh) { 172 if (!dir_has_error) { 173 EXT4_ERROR_FILE(file, 0, 174 "directory contains a " 175 "hole at offset %llu", 176 (unsigned long long) ctx->pos); 177 dir_has_error = 1; 178 } 179 /* corrupt size? Maybe no more blocks to read */ 180 if (ctx->pos > inode->i_blocks << 9) 181 break; 182 ctx->pos += sb->s_blocksize - offset; 183 continue; 184 } 185 186 /* Check the checksum */ 187 if (!buffer_verified(bh) && 188 !ext4_dirent_csum_verify(inode, 189 (struct ext4_dir_entry *)bh->b_data)) { 190 EXT4_ERROR_FILE(file, 0, "directory fails checksum " 191 "at offset %llu", 192 (unsigned long long)ctx->pos); 193 ctx->pos += sb->s_blocksize - offset; 194 brelse(bh); 195 bh = NULL; 196 continue; 197 } 198 set_buffer_verified(bh); 199 200 /* If the dir block has changed since the last call to 201 * readdir(2), then we might be pointing to an invalid 202 * dirent right now. Scan from the start of the block 203 * to make sure. */ 204 if (file->f_version != inode->i_version) { 205 for (i = 0; i < sb->s_blocksize && i < offset; ) { 206 de = (struct ext4_dir_entry_2 *) 207 (bh->b_data + i); 208 /* It's too expensive to do a full 209 * dirent test each time round this 210 * loop, but we do have to test at 211 * least that it is non-zero. A 212 * failure will be detected in the 213 * dirent test below. */ 214 if (ext4_rec_len_from_disk(de->rec_len, 215 sb->s_blocksize) < EXT4_DIR_REC_LEN(1)) 216 break; 217 i += ext4_rec_len_from_disk(de->rec_len, 218 sb->s_blocksize); 219 } 220 offset = i; 221 ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1)) 222 | offset; 223 file->f_version = inode->i_version; 224 } 225 226 while (ctx->pos < inode->i_size 227 && offset < sb->s_blocksize) { 228 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset); 229 if (ext4_check_dir_entry(inode, file, de, bh, 230 bh->b_data, bh->b_size, 231 offset)) { 232 /* 233 * On error, skip to the next block 234 */ 235 ctx->pos = (ctx->pos | 236 (sb->s_blocksize - 1)) + 1; 237 break; 238 } 239 offset += ext4_rec_len_from_disk(de->rec_len, 240 sb->s_blocksize); 241 if (le32_to_cpu(de->inode)) { 242 if (enc_ctx == NULL) { 243 /* Directory is not encrypted */ 244 if (!dir_emit(ctx, de->name, 245 de->name_len, 246 le32_to_cpu(de->inode), 247 get_dtype(sb, de->file_type))) 248 goto done; 249 } else { 250 int save_len = fname_crypto_str.len; 251 252 /* Directory is encrypted */ 253 err = ext4_fname_disk_to_usr(enc_ctx, 254 NULL, de, &fname_crypto_str); 255 fname_crypto_str.len = save_len; 256 if (err < 0) 257 goto errout; 258 if (!dir_emit(ctx, 259 fname_crypto_str.name, err, 260 le32_to_cpu(de->inode), 261 get_dtype(sb, de->file_type))) 262 goto done; 263 } 264 } 265 ctx->pos += ext4_rec_len_from_disk(de->rec_len, 266 sb->s_blocksize); 267 } 268 if ((ctx->pos < inode->i_size) && !dir_relax(inode)) 269 goto done; 270 brelse(bh); 271 bh = NULL; 272 offset = 0; 273 } 274 done: 275 err = 0; 276 errout: 277 #ifdef CONFIG_EXT4_FS_ENCRYPTION 278 ext4_put_fname_crypto_ctx(&enc_ctx); 279 ext4_fname_crypto_free_buffer(&fname_crypto_str); 280 #endif 281 brelse(bh); 282 return err; 283 } 284 285 static inline int is_32bit_api(void) 286 { 287 #ifdef CONFIG_COMPAT 288 return is_compat_task(); 289 #else 290 return (BITS_PER_LONG == 32); 291 #endif 292 } 293 294 /* 295 * These functions convert from the major/minor hash to an f_pos 296 * value for dx directories 297 * 298 * Upper layer (for example NFS) should specify FMODE_32BITHASH or 299 * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted 300 * directly on both 32-bit and 64-bit nodes, under such case, neither 301 * FMODE_32BITHASH nor FMODE_64BITHASH is specified. 302 */ 303 static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor) 304 { 305 if ((filp->f_mode & FMODE_32BITHASH) || 306 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 307 return major >> 1; 308 else 309 return ((__u64)(major >> 1) << 32) | (__u64)minor; 310 } 311 312 static inline __u32 pos2maj_hash(struct file *filp, loff_t pos) 313 { 314 if ((filp->f_mode & FMODE_32BITHASH) || 315 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 316 return (pos << 1) & 0xffffffff; 317 else 318 return ((pos >> 32) << 1) & 0xffffffff; 319 } 320 321 static inline __u32 pos2min_hash(struct file *filp, loff_t pos) 322 { 323 if ((filp->f_mode & FMODE_32BITHASH) || 324 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 325 return 0; 326 else 327 return pos & 0xffffffff; 328 } 329 330 /* 331 * Return 32- or 64-bit end-of-file for dx directories 332 */ 333 static inline loff_t ext4_get_htree_eof(struct file *filp) 334 { 335 if ((filp->f_mode & FMODE_32BITHASH) || 336 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 337 return EXT4_HTREE_EOF_32BIT; 338 else 339 return EXT4_HTREE_EOF_64BIT; 340 } 341 342 343 /* 344 * ext4_dir_llseek() calls generic_file_llseek_size to handle htree 345 * directories, where the "offset" is in terms of the filename hash 346 * value instead of the byte offset. 347 * 348 * Because we may return a 64-bit hash that is well beyond offset limits, 349 * we need to pass the max hash as the maximum allowable offset in 350 * the htree directory case. 351 * 352 * For non-htree, ext4_llseek already chooses the proper max offset. 353 */ 354 static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence) 355 { 356 struct inode *inode = file->f_mapping->host; 357 int dx_dir = is_dx_dir(inode); 358 loff_t htree_max = ext4_get_htree_eof(file); 359 360 if (likely(dx_dir)) 361 return generic_file_llseek_size(file, offset, whence, 362 htree_max, htree_max); 363 else 364 return ext4_llseek(file, offset, whence); 365 } 366 367 /* 368 * This structure holds the nodes of the red-black tree used to store 369 * the directory entry in hash order. 370 */ 371 struct fname { 372 __u32 hash; 373 __u32 minor_hash; 374 struct rb_node rb_hash; 375 struct fname *next; 376 __u32 inode; 377 __u8 name_len; 378 __u8 file_type; 379 char name[0]; 380 }; 381 382 /* 383 * This functoin implements a non-recursive way of freeing all of the 384 * nodes in the red-black tree. 385 */ 386 static void free_rb_tree_fname(struct rb_root *root) 387 { 388 struct fname *fname, *next; 389 390 rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash) 391 while (fname) { 392 struct fname *old = fname; 393 fname = fname->next; 394 kfree(old); 395 } 396 397 *root = RB_ROOT; 398 } 399 400 401 static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp, 402 loff_t pos) 403 { 404 struct dir_private_info *p; 405 406 p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL); 407 if (!p) 408 return NULL; 409 p->curr_hash = pos2maj_hash(filp, pos); 410 p->curr_minor_hash = pos2min_hash(filp, pos); 411 return p; 412 } 413 414 void ext4_htree_free_dir_info(struct dir_private_info *p) 415 { 416 free_rb_tree_fname(&p->root); 417 kfree(p); 418 } 419 420 /* 421 * Given a directory entry, enter it into the fname rb tree. 422 * 423 * When filename encryption is enabled, the dirent will hold the 424 * encrypted filename, while the htree will hold decrypted filename. 425 * The decrypted filename is passed in via ent_name. parameter. 426 */ 427 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash, 428 __u32 minor_hash, 429 struct ext4_dir_entry_2 *dirent, 430 struct ext4_str *ent_name) 431 { 432 struct rb_node **p, *parent = NULL; 433 struct fname *fname, *new_fn; 434 struct dir_private_info *info; 435 int len; 436 437 info = dir_file->private_data; 438 p = &info->root.rb_node; 439 440 /* Create and allocate the fname structure */ 441 len = sizeof(struct fname) + ent_name->len + 1; 442 new_fn = kzalloc(len, GFP_KERNEL); 443 if (!new_fn) 444 return -ENOMEM; 445 new_fn->hash = hash; 446 new_fn->minor_hash = minor_hash; 447 new_fn->inode = le32_to_cpu(dirent->inode); 448 new_fn->name_len = ent_name->len; 449 new_fn->file_type = dirent->file_type; 450 memcpy(new_fn->name, ent_name->name, ent_name->len); 451 new_fn->name[ent_name->len] = 0; 452 453 while (*p) { 454 parent = *p; 455 fname = rb_entry(parent, struct fname, rb_hash); 456 457 /* 458 * If the hash and minor hash match up, then we put 459 * them on a linked list. This rarely happens... 460 */ 461 if ((new_fn->hash == fname->hash) && 462 (new_fn->minor_hash == fname->minor_hash)) { 463 new_fn->next = fname->next; 464 fname->next = new_fn; 465 return 0; 466 } 467 468 if (new_fn->hash < fname->hash) 469 p = &(*p)->rb_left; 470 else if (new_fn->hash > fname->hash) 471 p = &(*p)->rb_right; 472 else if (new_fn->minor_hash < fname->minor_hash) 473 p = &(*p)->rb_left; 474 else /* if (new_fn->minor_hash > fname->minor_hash) */ 475 p = &(*p)->rb_right; 476 } 477 478 rb_link_node(&new_fn->rb_hash, parent, p); 479 rb_insert_color(&new_fn->rb_hash, &info->root); 480 return 0; 481 } 482 483 484 485 /* 486 * This is a helper function for ext4_dx_readdir. It calls filldir 487 * for all entres on the fname linked list. (Normally there is only 488 * one entry on the linked list, unless there are 62 bit hash collisions.) 489 */ 490 static int call_filldir(struct file *file, struct dir_context *ctx, 491 struct fname *fname) 492 { 493 struct dir_private_info *info = file->private_data; 494 struct inode *inode = file_inode(file); 495 struct super_block *sb = inode->i_sb; 496 497 if (!fname) { 498 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: " 499 "called with null fname?!?", __func__, __LINE__, 500 inode->i_ino, current->comm); 501 return 0; 502 } 503 ctx->pos = hash2pos(file, fname->hash, fname->minor_hash); 504 while (fname) { 505 if (!dir_emit(ctx, fname->name, 506 fname->name_len, 507 fname->inode, 508 get_dtype(sb, fname->file_type))) { 509 info->extra_fname = fname; 510 return 1; 511 } 512 fname = fname->next; 513 } 514 return 0; 515 } 516 517 static int ext4_dx_readdir(struct file *file, struct dir_context *ctx) 518 { 519 struct dir_private_info *info = file->private_data; 520 struct inode *inode = file_inode(file); 521 struct fname *fname; 522 int ret; 523 524 if (!info) { 525 info = ext4_htree_create_dir_info(file, ctx->pos); 526 if (!info) 527 return -ENOMEM; 528 file->private_data = info; 529 } 530 531 if (ctx->pos == ext4_get_htree_eof(file)) 532 return 0; /* EOF */ 533 534 /* Some one has messed with f_pos; reset the world */ 535 if (info->last_pos != ctx->pos) { 536 free_rb_tree_fname(&info->root); 537 info->curr_node = NULL; 538 info->extra_fname = NULL; 539 info->curr_hash = pos2maj_hash(file, ctx->pos); 540 info->curr_minor_hash = pos2min_hash(file, ctx->pos); 541 } 542 543 /* 544 * If there are any leftover names on the hash collision 545 * chain, return them first. 546 */ 547 if (info->extra_fname) { 548 if (call_filldir(file, ctx, info->extra_fname)) 549 goto finished; 550 info->extra_fname = NULL; 551 goto next_node; 552 } else if (!info->curr_node) 553 info->curr_node = rb_first(&info->root); 554 555 while (1) { 556 /* 557 * Fill the rbtree if we have no more entries, 558 * or the inode has changed since we last read in the 559 * cached entries. 560 */ 561 if ((!info->curr_node) || 562 (file->f_version != inode->i_version)) { 563 info->curr_node = NULL; 564 free_rb_tree_fname(&info->root); 565 file->f_version = inode->i_version; 566 ret = ext4_htree_fill_tree(file, info->curr_hash, 567 info->curr_minor_hash, 568 &info->next_hash); 569 if (ret < 0) 570 return ret; 571 if (ret == 0) { 572 ctx->pos = ext4_get_htree_eof(file); 573 break; 574 } 575 info->curr_node = rb_first(&info->root); 576 } 577 578 fname = rb_entry(info->curr_node, struct fname, rb_hash); 579 info->curr_hash = fname->hash; 580 info->curr_minor_hash = fname->minor_hash; 581 if (call_filldir(file, ctx, fname)) 582 break; 583 next_node: 584 info->curr_node = rb_next(info->curr_node); 585 if (info->curr_node) { 586 fname = rb_entry(info->curr_node, struct fname, 587 rb_hash); 588 info->curr_hash = fname->hash; 589 info->curr_minor_hash = fname->minor_hash; 590 } else { 591 if (info->next_hash == ~0) { 592 ctx->pos = ext4_get_htree_eof(file); 593 break; 594 } 595 info->curr_hash = info->next_hash; 596 info->curr_minor_hash = 0; 597 } 598 } 599 finished: 600 info->last_pos = ctx->pos; 601 return 0; 602 } 603 604 static int ext4_release_dir(struct inode *inode, struct file *filp) 605 { 606 if (filp->private_data) 607 ext4_htree_free_dir_info(filp->private_data); 608 609 return 0; 610 } 611 612 int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf, 613 int buf_size) 614 { 615 struct ext4_dir_entry_2 *de; 616 int nlen, rlen; 617 unsigned int offset = 0; 618 char *top; 619 620 de = (struct ext4_dir_entry_2 *)buf; 621 top = buf + buf_size; 622 while ((char *) de < top) { 623 if (ext4_check_dir_entry(dir, NULL, de, bh, 624 buf, buf_size, offset)) 625 return -EIO; 626 nlen = EXT4_DIR_REC_LEN(de->name_len); 627 rlen = ext4_rec_len_from_disk(de->rec_len, buf_size); 628 de = (struct ext4_dir_entry_2 *)((char *)de + rlen); 629 offset += rlen; 630 } 631 if ((char *) de > top) 632 return -EIO; 633 634 return 0; 635 } 636 637 const struct file_operations ext4_dir_operations = { 638 .llseek = ext4_dir_llseek, 639 .read = generic_read_dir, 640 .iterate = ext4_readdir, 641 .unlocked_ioctl = ext4_ioctl, 642 #ifdef CONFIG_COMPAT 643 .compat_ioctl = ext4_compat_ioctl, 644 #endif 645 .fsync = ext4_sync_file, 646 .release = ext4_release_dir, 647 }; 648