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 /* Directory is encrypted */ 251 err = ext4_fname_disk_to_usr(enc_ctx, 252 de, &fname_crypto_str); 253 if (err < 0) 254 goto errout; 255 if (!dir_emit(ctx, 256 fname_crypto_str.name, err, 257 le32_to_cpu(de->inode), 258 get_dtype(sb, de->file_type))) 259 goto done; 260 } 261 } 262 ctx->pos += ext4_rec_len_from_disk(de->rec_len, 263 sb->s_blocksize); 264 } 265 if ((ctx->pos < inode->i_size) && !dir_relax(inode)) 266 goto done; 267 brelse(bh); 268 bh = NULL; 269 offset = 0; 270 } 271 done: 272 err = 0; 273 errout: 274 #ifdef CONFIG_EXT4_FS_ENCRYPTION 275 ext4_put_fname_crypto_ctx(&enc_ctx); 276 ext4_fname_crypto_free_buffer(&fname_crypto_str); 277 #endif 278 brelse(bh); 279 return err; 280 } 281 282 static inline int is_32bit_api(void) 283 { 284 #ifdef CONFIG_COMPAT 285 return is_compat_task(); 286 #else 287 return (BITS_PER_LONG == 32); 288 #endif 289 } 290 291 /* 292 * These functions convert from the major/minor hash to an f_pos 293 * value for dx directories 294 * 295 * Upper layer (for example NFS) should specify FMODE_32BITHASH or 296 * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted 297 * directly on both 32-bit and 64-bit nodes, under such case, neither 298 * FMODE_32BITHASH nor FMODE_64BITHASH is specified. 299 */ 300 static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor) 301 { 302 if ((filp->f_mode & FMODE_32BITHASH) || 303 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 304 return major >> 1; 305 else 306 return ((__u64)(major >> 1) << 32) | (__u64)minor; 307 } 308 309 static inline __u32 pos2maj_hash(struct file *filp, loff_t pos) 310 { 311 if ((filp->f_mode & FMODE_32BITHASH) || 312 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 313 return (pos << 1) & 0xffffffff; 314 else 315 return ((pos >> 32) << 1) & 0xffffffff; 316 } 317 318 static inline __u32 pos2min_hash(struct file *filp, loff_t pos) 319 { 320 if ((filp->f_mode & FMODE_32BITHASH) || 321 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 322 return 0; 323 else 324 return pos & 0xffffffff; 325 } 326 327 /* 328 * Return 32- or 64-bit end-of-file for dx directories 329 */ 330 static inline loff_t ext4_get_htree_eof(struct file *filp) 331 { 332 if ((filp->f_mode & FMODE_32BITHASH) || 333 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 334 return EXT4_HTREE_EOF_32BIT; 335 else 336 return EXT4_HTREE_EOF_64BIT; 337 } 338 339 340 /* 341 * ext4_dir_llseek() calls generic_file_llseek_size to handle htree 342 * directories, where the "offset" is in terms of the filename hash 343 * value instead of the byte offset. 344 * 345 * Because we may return a 64-bit hash that is well beyond offset limits, 346 * we need to pass the max hash as the maximum allowable offset in 347 * the htree directory case. 348 * 349 * For non-htree, ext4_llseek already chooses the proper max offset. 350 */ 351 static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence) 352 { 353 struct inode *inode = file->f_mapping->host; 354 int dx_dir = is_dx_dir(inode); 355 loff_t htree_max = ext4_get_htree_eof(file); 356 357 if (likely(dx_dir)) 358 return generic_file_llseek_size(file, offset, whence, 359 htree_max, htree_max); 360 else 361 return ext4_llseek(file, offset, whence); 362 } 363 364 /* 365 * This structure holds the nodes of the red-black tree used to store 366 * the directory entry in hash order. 367 */ 368 struct fname { 369 __u32 hash; 370 __u32 minor_hash; 371 struct rb_node rb_hash; 372 struct fname *next; 373 __u32 inode; 374 __u8 name_len; 375 __u8 file_type; 376 char name[0]; 377 }; 378 379 /* 380 * This functoin implements a non-recursive way of freeing all of the 381 * nodes in the red-black tree. 382 */ 383 static void free_rb_tree_fname(struct rb_root *root) 384 { 385 struct fname *fname, *next; 386 387 rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash) 388 while (fname) { 389 struct fname *old = fname; 390 fname = fname->next; 391 kfree(old); 392 } 393 394 *root = RB_ROOT; 395 } 396 397 398 static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp, 399 loff_t pos) 400 { 401 struct dir_private_info *p; 402 403 p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL); 404 if (!p) 405 return NULL; 406 p->curr_hash = pos2maj_hash(filp, pos); 407 p->curr_minor_hash = pos2min_hash(filp, pos); 408 return p; 409 } 410 411 void ext4_htree_free_dir_info(struct dir_private_info *p) 412 { 413 free_rb_tree_fname(&p->root); 414 kfree(p); 415 } 416 417 /* 418 * Given a directory entry, enter it into the fname rb tree. 419 * 420 * When filename encryption is enabled, the dirent will hold the 421 * encrypted filename, while the htree will hold decrypted filename. 422 * The decrypted filename is passed in via ent_name. parameter. 423 */ 424 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash, 425 __u32 minor_hash, 426 struct ext4_dir_entry_2 *dirent, 427 struct ext4_str *ent_name) 428 { 429 struct rb_node **p, *parent = NULL; 430 struct fname *fname, *new_fn; 431 struct dir_private_info *info; 432 int len; 433 434 info = dir_file->private_data; 435 p = &info->root.rb_node; 436 437 /* Create and allocate the fname structure */ 438 len = sizeof(struct fname) + ent_name->len + 1; 439 new_fn = kzalloc(len, GFP_KERNEL); 440 if (!new_fn) 441 return -ENOMEM; 442 new_fn->hash = hash; 443 new_fn->minor_hash = minor_hash; 444 new_fn->inode = le32_to_cpu(dirent->inode); 445 new_fn->name_len = ent_name->len; 446 new_fn->file_type = dirent->file_type; 447 memcpy(new_fn->name, ent_name->name, ent_name->len); 448 new_fn->name[ent_name->len] = 0; 449 450 while (*p) { 451 parent = *p; 452 fname = rb_entry(parent, struct fname, rb_hash); 453 454 /* 455 * If the hash and minor hash match up, then we put 456 * them on a linked list. This rarely happens... 457 */ 458 if ((new_fn->hash == fname->hash) && 459 (new_fn->minor_hash == fname->minor_hash)) { 460 new_fn->next = fname->next; 461 fname->next = new_fn; 462 return 0; 463 } 464 465 if (new_fn->hash < fname->hash) 466 p = &(*p)->rb_left; 467 else if (new_fn->hash > fname->hash) 468 p = &(*p)->rb_right; 469 else if (new_fn->minor_hash < fname->minor_hash) 470 p = &(*p)->rb_left; 471 else /* if (new_fn->minor_hash > fname->minor_hash) */ 472 p = &(*p)->rb_right; 473 } 474 475 rb_link_node(&new_fn->rb_hash, parent, p); 476 rb_insert_color(&new_fn->rb_hash, &info->root); 477 return 0; 478 } 479 480 481 482 /* 483 * This is a helper function for ext4_dx_readdir. It calls filldir 484 * for all entres on the fname linked list. (Normally there is only 485 * one entry on the linked list, unless there are 62 bit hash collisions.) 486 */ 487 static int call_filldir(struct file *file, struct dir_context *ctx, 488 struct fname *fname) 489 { 490 struct dir_private_info *info = file->private_data; 491 struct inode *inode = file_inode(file); 492 struct super_block *sb = inode->i_sb; 493 494 if (!fname) { 495 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: " 496 "called with null fname?!?", __func__, __LINE__, 497 inode->i_ino, current->comm); 498 return 0; 499 } 500 ctx->pos = hash2pos(file, fname->hash, fname->minor_hash); 501 while (fname) { 502 if (!dir_emit(ctx, fname->name, 503 fname->name_len, 504 fname->inode, 505 get_dtype(sb, fname->file_type))) { 506 info->extra_fname = fname; 507 return 1; 508 } 509 fname = fname->next; 510 } 511 return 0; 512 } 513 514 static int ext4_dx_readdir(struct file *file, struct dir_context *ctx) 515 { 516 struct dir_private_info *info = file->private_data; 517 struct inode *inode = file_inode(file); 518 struct fname *fname; 519 int ret; 520 521 if (!info) { 522 info = ext4_htree_create_dir_info(file, ctx->pos); 523 if (!info) 524 return -ENOMEM; 525 file->private_data = info; 526 } 527 528 if (ctx->pos == ext4_get_htree_eof(file)) 529 return 0; /* EOF */ 530 531 /* Some one has messed with f_pos; reset the world */ 532 if (info->last_pos != ctx->pos) { 533 free_rb_tree_fname(&info->root); 534 info->curr_node = NULL; 535 info->extra_fname = NULL; 536 info->curr_hash = pos2maj_hash(file, ctx->pos); 537 info->curr_minor_hash = pos2min_hash(file, ctx->pos); 538 } 539 540 /* 541 * If there are any leftover names on the hash collision 542 * chain, return them first. 543 */ 544 if (info->extra_fname) { 545 if (call_filldir(file, ctx, info->extra_fname)) 546 goto finished; 547 info->extra_fname = NULL; 548 goto next_node; 549 } else if (!info->curr_node) 550 info->curr_node = rb_first(&info->root); 551 552 while (1) { 553 /* 554 * Fill the rbtree if we have no more entries, 555 * or the inode has changed since we last read in the 556 * cached entries. 557 */ 558 if ((!info->curr_node) || 559 (file->f_version != inode->i_version)) { 560 info->curr_node = NULL; 561 free_rb_tree_fname(&info->root); 562 file->f_version = inode->i_version; 563 ret = ext4_htree_fill_tree(file, info->curr_hash, 564 info->curr_minor_hash, 565 &info->next_hash); 566 if (ret < 0) 567 return ret; 568 if (ret == 0) { 569 ctx->pos = ext4_get_htree_eof(file); 570 break; 571 } 572 info->curr_node = rb_first(&info->root); 573 } 574 575 fname = rb_entry(info->curr_node, struct fname, rb_hash); 576 info->curr_hash = fname->hash; 577 info->curr_minor_hash = fname->minor_hash; 578 if (call_filldir(file, ctx, fname)) 579 break; 580 next_node: 581 info->curr_node = rb_next(info->curr_node); 582 if (info->curr_node) { 583 fname = rb_entry(info->curr_node, struct fname, 584 rb_hash); 585 info->curr_hash = fname->hash; 586 info->curr_minor_hash = fname->minor_hash; 587 } else { 588 if (info->next_hash == ~0) { 589 ctx->pos = ext4_get_htree_eof(file); 590 break; 591 } 592 info->curr_hash = info->next_hash; 593 info->curr_minor_hash = 0; 594 } 595 } 596 finished: 597 info->last_pos = ctx->pos; 598 return 0; 599 } 600 601 static int ext4_release_dir(struct inode *inode, struct file *filp) 602 { 603 if (filp->private_data) 604 ext4_htree_free_dir_info(filp->private_data); 605 606 return 0; 607 } 608 609 int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf, 610 int buf_size) 611 { 612 struct ext4_dir_entry_2 *de; 613 int nlen, rlen; 614 unsigned int offset = 0; 615 char *top; 616 617 de = (struct ext4_dir_entry_2 *)buf; 618 top = buf + buf_size; 619 while ((char *) de < top) { 620 if (ext4_check_dir_entry(dir, NULL, de, bh, 621 buf, buf_size, offset)) 622 return -EIO; 623 nlen = EXT4_DIR_REC_LEN(de->name_len); 624 rlen = ext4_rec_len_from_disk(de->rec_len, buf_size); 625 de = (struct ext4_dir_entry_2 *)((char *)de + rlen); 626 offset += rlen; 627 } 628 if ((char *) de > top) 629 return -EIO; 630 631 return 0; 632 } 633 634 const struct file_operations ext4_dir_operations = { 635 .llseek = ext4_dir_llseek, 636 .read = generic_read_dir, 637 .iterate = ext4_readdir, 638 .unlocked_ioctl = ext4_ioctl, 639 #ifdef CONFIG_COMPAT 640 .compat_ioctl = ext4_compat_ioctl, 641 #endif 642 .fsync = ext4_sync_file, 643 .release = ext4_release_dir, 644 }; 645