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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/jbd2.h>
26#include <linux/buffer_head.h>
27#include <linux/slab.h>
28#include <linux/rbtree.h>
29#include "ext4.h"
30
31static unsigned char ext4_filetype_table[] = {
32 DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
33};
34
35static int ext4_dx_readdir(struct file *filp,
36 void *dirent, filldir_t filldir);
37
38static unsigned char get_dtype(struct super_block *sb, int filetype)
39{
40 if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FILETYPE) ||
41 (filetype >= EXT4_FT_MAX))
42 return DT_UNKNOWN;
43
44 return (ext4_filetype_table[filetype]);
45}
46
47/**
48 * Check if the given dir-inode refers to an htree-indexed directory
49 * (or a directory which chould potentially get coverted to use htree
50 * indexing).
51 *
52 * Return 1 if it is a dx dir, 0 if not
53 */
54static int is_dx_dir(struct inode *inode)
55{
56 struct super_block *sb = inode->i_sb;
57
58 if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb,
59 EXT4_FEATURE_COMPAT_DIR_INDEX) &&
60 ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) ||
61 ((inode->i_size >> sb->s_blocksize_bits) == 1)))
62 return 1;
63
64 return 0;
65}
66
67/*
68 * Return 0 if the directory entry is OK, and 1 if there is a problem
69 *
70 * Note: this is the opposite of what ext2 and ext3 historically returned...
71 */
72int __ext4_check_dir_entry(const char *function, unsigned int line,
73 struct inode *dir, struct file *filp,
74 struct ext4_dir_entry_2 *de,
75 struct buffer_head *bh,
76 unsigned int offset)
77{
78 const char *error_msg = NULL;
79 const int rlen = ext4_rec_len_from_disk(de->rec_len,
80 dir->i_sb->s_blocksize);
81
82 if (unlikely(rlen < EXT4_DIR_REC_LEN(1)))
83 error_msg = "rec_len is smaller than minimal";
84 else if (unlikely(rlen % 4 != 0))
85 error_msg = "rec_len % 4 != 0";
86 else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len)))
87 error_msg = "rec_len is too small for name_len";
88 else if (unlikely(((char *) de - bh->b_data) + rlen >
89 dir->i_sb->s_blocksize))
90 error_msg = "directory entry across blocks";
91 else if (unlikely(le32_to_cpu(de->inode) >
92 le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)))
93 error_msg = "inode out of bounds";
94 else
95 return 0;
96
97 if (filp)
98 ext4_error_file(filp, function, line, bh->b_blocknr,
99 "bad entry in directory: %s - offset=%u(%u), "
100 "inode=%u, rec_len=%d, name_len=%d",
101 error_msg, (unsigned) (offset % bh->b_size),
102 offset, le32_to_cpu(de->inode),
103 rlen, de->name_len);
104 else
105 ext4_error_inode(dir, function, line, bh->b_blocknr,
106 "bad entry in directory: %s - offset=%u(%u), "
107 "inode=%u, rec_len=%d, name_len=%d",
108 error_msg, (unsigned) (offset % bh->b_size),
109 offset, le32_to_cpu(de->inode),
110 rlen, de->name_len);
111
112 return 1;
113}
114
115static int ext4_readdir(struct file *filp,
116 void *dirent, filldir_t filldir)
117{
118 int error = 0;
119 unsigned int offset;
120 int i, stored;
121 struct ext4_dir_entry_2 *de;
122 int err;
123 struct inode *inode = filp->f_path.dentry->d_inode;
124 struct super_block *sb = inode->i_sb;
125 int ret = 0;
126 int dir_has_error = 0;
127
128 if (is_dx_dir(inode)) {
129 err = ext4_dx_readdir(filp, dirent, filldir);
130 if (err != ERR_BAD_DX_DIR) {
131 ret = err;
132 goto out;
133 }
134 /*
135 * We don't set the inode dirty flag since it's not
136 * critical that it get flushed back to the disk.
137 */
138 ext4_clear_inode_flag(filp->f_path.dentry->d_inode,
139 EXT4_INODE_INDEX);
140 }
141 stored = 0;
142 offset = filp->f_pos & (sb->s_blocksize - 1);
143
144 while (!error && !stored && filp->f_pos < inode->i_size) {
145 struct ext4_map_blocks map;
146 struct buffer_head *bh = NULL;
147
148 map.m_lblk = filp->f_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(&filp->f_ra, index))
155 page_cache_sync_readahead(
156 sb->s_bdev->bd_inode->i_mapping,
157 &filp->f_ra, filp,
158 index, 1);
159 filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
160 bh = ext4_bread(NULL, inode, map.m_lblk, 0, &err);
161 }
162
163 /*
164 * We ignore I/O errors on directories so users have a chance
165 * of recovering data when there's a bad sector
166 */
167 if (!bh) {
168 if (!dir_has_error) {
169 EXT4_ERROR_FILE(filp, 0,
170 "directory contains a "
171 "hole at offset %llu",
172 (unsigned long long) filp->f_pos);
173 dir_has_error = 1;
174 }
175 /* corrupt size? Maybe no more blocks to read */
176 if (filp->f_pos > inode->i_blocks << 9)
177 break;
178 filp->f_pos += sb->s_blocksize - offset;
179 continue;
180 }
181
182 /* Check the checksum */
183 if (!buffer_verified(bh) &&
184 !ext4_dirent_csum_verify(inode,
185 (struct ext4_dir_entry *)bh->b_data)) {
186 EXT4_ERROR_FILE(filp, 0, "directory fails checksum "
187 "at offset %llu",
188 (unsigned long long)filp->f_pos);
189 filp->f_pos += sb->s_blocksize - offset;
190 continue;
191 }
192 set_buffer_verified(bh);
193
194revalidate:
195 /* If the dir block has changed since the last call to
196 * readdir(2), then we might be pointing to an invalid
197 * dirent right now. Scan from the start of the block
198 * to make sure. */
199 if (filp->f_version != inode->i_version) {
200 for (i = 0; i < sb->s_blocksize && i < offset; ) {
201 de = (struct ext4_dir_entry_2 *)
202 (bh->b_data + i);
203 /* It's too expensive to do a full
204 * dirent test each time round this
205 * loop, but we do have to test at
206 * least that it is non-zero. A
207 * failure will be detected in the
208 * dirent test below. */
209 if (ext4_rec_len_from_disk(de->rec_len,
210 sb->s_blocksize) < EXT4_DIR_REC_LEN(1))
211 break;
212 i += ext4_rec_len_from_disk(de->rec_len,
213 sb->s_blocksize);
214 }
215 offset = i;
216 filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
217 | offset;
218 filp->f_version = inode->i_version;
219 }
220
221 while (!error && filp->f_pos < inode->i_size
222 && offset < sb->s_blocksize) {
223 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
224 if (ext4_check_dir_entry(inode, filp, de,
225 bh, offset)) {
226 /*
227 * On error, skip the f_pos to the next block
228 */
229 filp->f_pos = (filp->f_pos |
230 (sb->s_blocksize - 1)) + 1;
231 brelse(bh);
232 ret = stored;
233 goto out;
234 }
235 offset += ext4_rec_len_from_disk(de->rec_len,
236 sb->s_blocksize);
237 if (le32_to_cpu(de->inode)) {
238 /* We might block in the next section
239 * if the data destination is
240 * currently swapped out. So, use a
241 * version stamp to detect whether or
242 * not the directory has been modified
243 * during the copy operation.
244 */
245 u64 version = filp->f_version;
246
247 error = filldir(dirent, de->name,
248 de->name_len,
249 filp->f_pos,
250 le32_to_cpu(de->inode),
251 get_dtype(sb, de->file_type));
252 if (error)
253 break;
254 if (version != filp->f_version)
255 goto revalidate;
256 stored++;
257 }
258 filp->f_pos += ext4_rec_len_from_disk(de->rec_len,
259 sb->s_blocksize);
260 }
261 offset = 0;
262 brelse(bh);
263 }
264out:
265 return ret;
266}
267
268static inline int is_32bit_api(void)
269{
270#ifdef CONFIG_COMPAT
271 return is_compat_task();
272#else
273 return (BITS_PER_LONG == 32);
274#endif
275}
276
277/*
278 * These functions convert from the major/minor hash to an f_pos
279 * value for dx directories
280 *
281 * Upper layer (for example NFS) should specify FMODE_32BITHASH or
282 * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted
283 * directly on both 32-bit and 64-bit nodes, under such case, neither
284 * FMODE_32BITHASH nor FMODE_64BITHASH is specified.
285 */
286static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor)
287{
288 if ((filp->f_mode & FMODE_32BITHASH) ||
289 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
290 return major >> 1;
291 else
292 return ((__u64)(major >> 1) << 32) | (__u64)minor;
293}
294
295static inline __u32 pos2maj_hash(struct file *filp, loff_t pos)
296{
297 if ((filp->f_mode & FMODE_32BITHASH) ||
298 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
299 return (pos << 1) & 0xffffffff;
300 else
301 return ((pos >> 32) << 1) & 0xffffffff;
302}
303
304static inline __u32 pos2min_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 0;
309 else
310 return pos & 0xffffffff;
311}
312
313/*
314 * Return 32- or 64-bit end-of-file for dx directories
315 */
316static inline loff_t ext4_get_htree_eof(struct file *filp)
317{
318 if ((filp->f_mode & FMODE_32BITHASH) ||
319 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
320 return EXT4_HTREE_EOF_32BIT;
321 else
322 return EXT4_HTREE_EOF_64BIT;
323}
324
325
326/*
327 * ext4_dir_llseek() based on generic_file_llseek() to handle both
328 * non-htree and htree directories, where the "offset" is in terms
329 * of the filename hash value instead of the byte offset.
330 *
331 * NOTE: offsets obtained *before* ext4_set_inode_flag(dir, EXT4_INODE_INDEX)
332 * will be invalid once the directory was converted into a dx directory
333 */
334loff_t ext4_dir_llseek(struct file *file, loff_t offset, int origin)
335{
336 struct inode *inode = file->f_mapping->host;
337 loff_t ret = -EINVAL;
338 int dx_dir = is_dx_dir(inode);
339
340 mutex_lock(&inode->i_mutex);
341
342 /* NOTE: relative offsets with dx directories might not work
343 * as expected, as it is difficult to figure out the
344 * correct offset between dx hashes */
345
346 switch (origin) {
347 case SEEK_END:
348 if (unlikely(offset > 0))
349 goto out_err; /* not supported for directories */
350
351 /* so only negative offsets are left, does that have a
352 * meaning for directories at all? */
353 if (dx_dir)
354 offset += ext4_get_htree_eof(file);
355 else
356 offset += inode->i_size;
357 break;
358 case SEEK_CUR:
359 /*
360 * Here we special-case the lseek(fd, 0, SEEK_CUR)
361 * position-querying operation. Avoid rewriting the "same"
362 * f_pos value back to the file because a concurrent read(),
363 * write() or lseek() might have altered it
364 */
365 if (offset == 0) {
366 offset = file->f_pos;
367 goto out_ok;
368 }
369
370 offset += file->f_pos;
371 break;
372 }
373
374 if (unlikely(offset < 0))
375 goto out_err;
376
377 if (!dx_dir) {
378 if (offset > inode->i_sb->s_maxbytes)
379 goto out_err;
380 } else if (offset > ext4_get_htree_eof(file))
381 goto out_err;
382
383 /* Special lock needed here? */
384 if (offset != file->f_pos) {
385 file->f_pos = offset;
386 file->f_version = 0;
387 }
388
389out_ok:
390 ret = offset;
391out_err:
392 mutex_unlock(&inode->i_mutex);
393
394 return ret;
395}
396
397/*
398 * This structure holds the nodes of the red-black tree used to store
399 * the directory entry in hash order.
400 */
401struct fname {
402 __u32 hash;
403 __u32 minor_hash;
404 struct rb_node rb_hash;
405 struct fname *next;
406 __u32 inode;
407 __u8 name_len;
408 __u8 file_type;
409 char name[0];
410};
411
412/*
413 * This functoin implements a non-recursive way of freeing all of the
414 * nodes in the red-black tree.
415 */
416static void free_rb_tree_fname(struct rb_root *root)
417{
418 struct rb_node *n = root->rb_node;
419 struct rb_node *parent;
420 struct fname *fname;
421
422 while (n) {
423 /* Do the node's children first */
424 if (n->rb_left) {
425 n = n->rb_left;
426 continue;
427 }
428 if (n->rb_right) {
429 n = n->rb_right;
430 continue;
431 }
432 /*
433 * The node has no children; free it, and then zero
434 * out parent's link to it. Finally go to the
435 * beginning of the loop and try to free the parent
436 * node.
437 */
438 parent = rb_parent(n);
439 fname = rb_entry(n, struct fname, rb_hash);
440 while (fname) {
441 struct fname *old = fname;
442 fname = fname->next;
443 kfree(old);
444 }
445 if (!parent)
446 *root = RB_ROOT;
447 else if (parent->rb_left == n)
448 parent->rb_left = NULL;
449 else if (parent->rb_right == n)
450 parent->rb_right = NULL;
451 n = parent;
452 }
453}
454
455
456static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp,
457 loff_t pos)
458{
459 struct dir_private_info *p;
460
461 p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
462 if (!p)
463 return NULL;
464 p->curr_hash = pos2maj_hash(filp, pos);
465 p->curr_minor_hash = pos2min_hash(filp, pos);
466 return p;
467}
468
469void ext4_htree_free_dir_info(struct dir_private_info *p)
470{
471 free_rb_tree_fname(&p->root);
472 kfree(p);
473}
474
475/*
476 * Given a directory entry, enter it into the fname rb tree.
477 */
478int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
479 __u32 minor_hash,
480 struct ext4_dir_entry_2 *dirent)
481{
482 struct rb_node **p, *parent = NULL;
483 struct fname *fname, *new_fn;
484 struct dir_private_info *info;
485 int len;
486
487 info = dir_file->private_data;
488 p = &info->root.rb_node;
489
490 /* Create and allocate the fname structure */
491 len = sizeof(struct fname) + dirent->name_len + 1;
492 new_fn = kzalloc(len, GFP_KERNEL);
493 if (!new_fn)
494 return -ENOMEM;
495 new_fn->hash = hash;
496 new_fn->minor_hash = minor_hash;
497 new_fn->inode = le32_to_cpu(dirent->inode);
498 new_fn->name_len = dirent->name_len;
499 new_fn->file_type = dirent->file_type;
500 memcpy(new_fn->name, dirent->name, dirent->name_len);
501 new_fn->name[dirent->name_len] = 0;
502
503 while (*p) {
504 parent = *p;
505 fname = rb_entry(parent, struct fname, rb_hash);
506
507 /*
508 * If the hash and minor hash match up, then we put
509 * them on a linked list. This rarely happens...
510 */
511 if ((new_fn->hash == fname->hash) &&
512 (new_fn->minor_hash == fname->minor_hash)) {
513 new_fn->next = fname->next;
514 fname->next = new_fn;
515 return 0;
516 }
517
518 if (new_fn->hash < fname->hash)
519 p = &(*p)->rb_left;
520 else if (new_fn->hash > fname->hash)
521 p = &(*p)->rb_right;
522 else if (new_fn->minor_hash < fname->minor_hash)
523 p = &(*p)->rb_left;
524 else /* if (new_fn->minor_hash > fname->minor_hash) */
525 p = &(*p)->rb_right;
526 }
527
528 rb_link_node(&new_fn->rb_hash, parent, p);
529 rb_insert_color(&new_fn->rb_hash, &info->root);
530 return 0;
531}
532
533
534
535/*
536 * This is a helper function for ext4_dx_readdir. It calls filldir
537 * for all entres on the fname linked list. (Normally there is only
538 * one entry on the linked list, unless there are 62 bit hash collisions.)
539 */
540static int call_filldir(struct file *filp, void *dirent,
541 filldir_t filldir, struct fname *fname)
542{
543 struct dir_private_info *info = filp->private_data;
544 loff_t curr_pos;
545 struct inode *inode = filp->f_path.dentry->d_inode;
546 struct super_block *sb;
547 int error;
548
549 sb = inode->i_sb;
550
551 if (!fname) {
552 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: "
553 "called with null fname?!?", __func__, __LINE__,
554 inode->i_ino, current->comm);
555 return 0;
556 }
557 curr_pos = hash2pos(filp, fname->hash, fname->minor_hash);
558 while (fname) {
559 error = filldir(dirent, fname->name,
560 fname->name_len, curr_pos,
561 fname->inode,
562 get_dtype(sb, fname->file_type));
563 if (error) {
564 filp->f_pos = curr_pos;
565 info->extra_fname = fname;
566 return error;
567 }
568 fname = fname->next;
569 }
570 return 0;
571}
572
573static int ext4_dx_readdir(struct file *filp,
574 void *dirent, filldir_t filldir)
575{
576 struct dir_private_info *info = filp->private_data;
577 struct inode *inode = filp->f_path.dentry->d_inode;
578 struct fname *fname;
579 int ret;
580
581 if (!info) {
582 info = ext4_htree_create_dir_info(filp, filp->f_pos);
583 if (!info)
584 return -ENOMEM;
585 filp->private_data = info;
586 }
587
588 if (filp->f_pos == ext4_get_htree_eof(filp))
589 return 0; /* EOF */
590
591 /* Some one has messed with f_pos; reset the world */
592 if (info->last_pos != filp->f_pos) {
593 free_rb_tree_fname(&info->root);
594 info->curr_node = NULL;
595 info->extra_fname = NULL;
596 info->curr_hash = pos2maj_hash(filp, filp->f_pos);
597 info->curr_minor_hash = pos2min_hash(filp, filp->f_pos);
598 }
599
600 /*
601 * If there are any leftover names on the hash collision
602 * chain, return them first.
603 */
604 if (info->extra_fname) {
605 if (call_filldir(filp, dirent, filldir, info->extra_fname))
606 goto finished;
607 info->extra_fname = NULL;
608 goto next_node;
609 } else if (!info->curr_node)
610 info->curr_node = rb_first(&info->root);
611
612 while (1) {
613 /*
614 * Fill the rbtree if we have no more entries,
615 * or the inode has changed since we last read in the
616 * cached entries.
617 */
618 if ((!info->curr_node) ||
619 (filp->f_version != inode->i_version)) {
620 info->curr_node = NULL;
621 free_rb_tree_fname(&info->root);
622 filp->f_version = inode->i_version;
623 ret = ext4_htree_fill_tree(filp, info->curr_hash,
624 info->curr_minor_hash,
625 &info->next_hash);
626 if (ret < 0)
627 return ret;
628 if (ret == 0) {
629 filp->f_pos = ext4_get_htree_eof(filp);
630 break;
631 }
632 info->curr_node = rb_first(&info->root);
633 }
634
635 fname = rb_entry(info->curr_node, struct fname, rb_hash);
636 info->curr_hash = fname->hash;
637 info->curr_minor_hash = fname->minor_hash;
638 if (call_filldir(filp, dirent, filldir, fname))
639 break;
640 next_node:
641 info->curr_node = rb_next(info->curr_node);
642 if (info->curr_node) {
643 fname = rb_entry(info->curr_node, struct fname,
644 rb_hash);
645 info->curr_hash = fname->hash;
646 info->curr_minor_hash = fname->minor_hash;
647 } else {
648 if (info->next_hash == ~0) {
649 filp->f_pos = ext4_get_htree_eof(filp);
650 break;
651 }
652 info->curr_hash = info->next_hash;
653 info->curr_minor_hash = 0;
654 }
655 }
656finished:
657 info->last_pos = filp->f_pos;
658 return 0;
659}
660
661static int ext4_release_dir(struct inode *inode, struct file *filp)
662{
663 if (filp->private_data)
664 ext4_htree_free_dir_info(filp->private_data);
665
666 return 0;
667}
668
669const struct file_operations ext4_dir_operations = {
670 .llseek = ext4_dir_llseek,
671 .read = generic_read_dir,
672 .readdir = ext4_readdir,
673 .unlocked_ioctl = ext4_ioctl,
674#ifdef CONFIG_COMPAT
675 .compat_ioctl = ext4_compat_ioctl,
676#endif
677 .fsync = ext4_sync_file,
678 .release = ext4_release_dir,
679};
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
33static 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 */
45static 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
58static 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 */
78int __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
126static 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 offset = 0;
307 }
308done:
309 err = 0;
310errout:
311 fscrypt_fname_free_buffer(&fstr);
312 brelse(bh);
313 return err;
314}
315
316static inline int is_32bit_api(void)
317{
318#ifdef CONFIG_COMPAT
319 return in_compat_syscall();
320#else
321 return (BITS_PER_LONG == 32);
322#endif
323}
324
325/*
326 * These functions convert from the major/minor hash to an f_pos
327 * value for dx directories
328 *
329 * Upper layer (for example NFS) should specify FMODE_32BITHASH or
330 * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted
331 * directly on both 32-bit and 64-bit nodes, under such case, neither
332 * FMODE_32BITHASH nor FMODE_64BITHASH is specified.
333 */
334static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor)
335{
336 if ((filp->f_mode & FMODE_32BITHASH) ||
337 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
338 return major >> 1;
339 else
340 return ((__u64)(major >> 1) << 32) | (__u64)minor;
341}
342
343static inline __u32 pos2maj_hash(struct file *filp, loff_t pos)
344{
345 if ((filp->f_mode & FMODE_32BITHASH) ||
346 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
347 return (pos << 1) & 0xffffffff;
348 else
349 return ((pos >> 32) << 1) & 0xffffffff;
350}
351
352static inline __u32 pos2min_hash(struct file *filp, loff_t pos)
353{
354 if ((filp->f_mode & FMODE_32BITHASH) ||
355 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
356 return 0;
357 else
358 return pos & 0xffffffff;
359}
360
361/*
362 * Return 32- or 64-bit end-of-file for dx directories
363 */
364static inline loff_t ext4_get_htree_eof(struct file *filp)
365{
366 if ((filp->f_mode & FMODE_32BITHASH) ||
367 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
368 return EXT4_HTREE_EOF_32BIT;
369 else
370 return EXT4_HTREE_EOF_64BIT;
371}
372
373
374/*
375 * ext4_dir_llseek() calls generic_file_llseek_size to handle htree
376 * directories, where the "offset" is in terms of the filename hash
377 * value instead of the byte offset.
378 *
379 * Because we may return a 64-bit hash that is well beyond offset limits,
380 * we need to pass the max hash as the maximum allowable offset in
381 * the htree directory case.
382 *
383 * For non-htree, ext4_llseek already chooses the proper max offset.
384 */
385static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence)
386{
387 struct inode *inode = file->f_mapping->host;
388 int dx_dir = is_dx_dir(inode);
389 loff_t ret, htree_max = ext4_get_htree_eof(file);
390
391 if (likely(dx_dir))
392 ret = generic_file_llseek_size(file, offset, whence,
393 htree_max, htree_max);
394 else
395 ret = ext4_llseek(file, offset, whence);
396 file->f_version = inode_peek_iversion(inode) - 1;
397 return ret;
398}
399
400/*
401 * This structure holds the nodes of the red-black tree used to store
402 * the directory entry in hash order.
403 */
404struct fname {
405 __u32 hash;
406 __u32 minor_hash;
407 struct rb_node rb_hash;
408 struct fname *next;
409 __u32 inode;
410 __u8 name_len;
411 __u8 file_type;
412 char name[];
413};
414
415/*
416 * This functoin implements a non-recursive way of freeing all of the
417 * nodes in the red-black tree.
418 */
419static void free_rb_tree_fname(struct rb_root *root)
420{
421 struct fname *fname, *next;
422
423 rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash)
424 while (fname) {
425 struct fname *old = fname;
426 fname = fname->next;
427 kfree(old);
428 }
429
430 *root = RB_ROOT;
431}
432
433
434static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp,
435 loff_t pos)
436{
437 struct dir_private_info *p;
438
439 p = kzalloc(sizeof(*p), GFP_KERNEL);
440 if (!p)
441 return NULL;
442 p->curr_hash = pos2maj_hash(filp, pos);
443 p->curr_minor_hash = pos2min_hash(filp, pos);
444 return p;
445}
446
447void ext4_htree_free_dir_info(struct dir_private_info *p)
448{
449 free_rb_tree_fname(&p->root);
450 kfree(p);
451}
452
453/*
454 * Given a directory entry, enter it into the fname rb tree.
455 *
456 * When filename encryption is enabled, the dirent will hold the
457 * encrypted filename, while the htree will hold decrypted filename.
458 * The decrypted filename is passed in via ent_name. parameter.
459 */
460int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
461 __u32 minor_hash,
462 struct ext4_dir_entry_2 *dirent,
463 struct fscrypt_str *ent_name)
464{
465 struct rb_node **p, *parent = NULL;
466 struct fname *fname, *new_fn;
467 struct dir_private_info *info;
468 int len;
469
470 info = dir_file->private_data;
471 p = &info->root.rb_node;
472
473 /* Create and allocate the fname structure */
474 len = sizeof(struct fname) + ent_name->len + 1;
475 new_fn = kzalloc(len, GFP_KERNEL);
476 if (!new_fn)
477 return -ENOMEM;
478 new_fn->hash = hash;
479 new_fn->minor_hash = minor_hash;
480 new_fn->inode = le32_to_cpu(dirent->inode);
481 new_fn->name_len = ent_name->len;
482 new_fn->file_type = dirent->file_type;
483 memcpy(new_fn->name, ent_name->name, ent_name->len);
484
485 while (*p) {
486 parent = *p;
487 fname = rb_entry(parent, struct fname, rb_hash);
488
489 /*
490 * If the hash and minor hash match up, then we put
491 * them on a linked list. This rarely happens...
492 */
493 if ((new_fn->hash == fname->hash) &&
494 (new_fn->minor_hash == fname->minor_hash)) {
495 new_fn->next = fname->next;
496 fname->next = new_fn;
497 return 0;
498 }
499
500 if (new_fn->hash < fname->hash)
501 p = &(*p)->rb_left;
502 else if (new_fn->hash > fname->hash)
503 p = &(*p)->rb_right;
504 else if (new_fn->minor_hash < fname->minor_hash)
505 p = &(*p)->rb_left;
506 else /* if (new_fn->minor_hash > fname->minor_hash) */
507 p = &(*p)->rb_right;
508 }
509
510 rb_link_node(&new_fn->rb_hash, parent, p);
511 rb_insert_color(&new_fn->rb_hash, &info->root);
512 return 0;
513}
514
515
516
517/*
518 * This is a helper function for ext4_dx_readdir. It calls filldir
519 * for all entres on the fname linked list. (Normally there is only
520 * one entry on the linked list, unless there are 62 bit hash collisions.)
521 */
522static int call_filldir(struct file *file, struct dir_context *ctx,
523 struct fname *fname)
524{
525 struct dir_private_info *info = file->private_data;
526 struct inode *inode = file_inode(file);
527 struct super_block *sb = inode->i_sb;
528
529 if (!fname) {
530 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: "
531 "called with null fname?!?", __func__, __LINE__,
532 inode->i_ino, current->comm);
533 return 0;
534 }
535 ctx->pos = hash2pos(file, fname->hash, fname->minor_hash);
536 while (fname) {
537 if (!dir_emit(ctx, fname->name,
538 fname->name_len,
539 fname->inode,
540 get_dtype(sb, fname->file_type))) {
541 info->extra_fname = fname;
542 return 1;
543 }
544 fname = fname->next;
545 }
546 return 0;
547}
548
549static int ext4_dx_readdir(struct file *file, struct dir_context *ctx)
550{
551 struct dir_private_info *info = file->private_data;
552 struct inode *inode = file_inode(file);
553 struct fname *fname;
554 int ret = 0;
555
556 if (!info) {
557 info = ext4_htree_create_dir_info(file, ctx->pos);
558 if (!info)
559 return -ENOMEM;
560 file->private_data = info;
561 }
562
563 if (ctx->pos == ext4_get_htree_eof(file))
564 return 0; /* EOF */
565
566 /* Some one has messed with f_pos; reset the world */
567 if (info->last_pos != ctx->pos) {
568 free_rb_tree_fname(&info->root);
569 info->curr_node = NULL;
570 info->extra_fname = NULL;
571 info->curr_hash = pos2maj_hash(file, ctx->pos);
572 info->curr_minor_hash = pos2min_hash(file, ctx->pos);
573 }
574
575 /*
576 * If there are any leftover names on the hash collision
577 * chain, return them first.
578 */
579 if (info->extra_fname) {
580 if (call_filldir(file, ctx, info->extra_fname))
581 goto finished;
582 info->extra_fname = NULL;
583 goto next_node;
584 } else if (!info->curr_node)
585 info->curr_node = rb_first(&info->root);
586
587 while (1) {
588 /*
589 * Fill the rbtree if we have no more entries,
590 * or the inode has changed since we last read in the
591 * cached entries.
592 */
593 if ((!info->curr_node) ||
594 !inode_eq_iversion(inode, file->f_version)) {
595 info->curr_node = NULL;
596 free_rb_tree_fname(&info->root);
597 file->f_version = inode_query_iversion(inode);
598 ret = ext4_htree_fill_tree(file, info->curr_hash,
599 info->curr_minor_hash,
600 &info->next_hash);
601 if (ret < 0)
602 goto finished;
603 if (ret == 0) {
604 ctx->pos = ext4_get_htree_eof(file);
605 break;
606 }
607 info->curr_node = rb_first(&info->root);
608 }
609
610 fname = rb_entry(info->curr_node, struct fname, rb_hash);
611 info->curr_hash = fname->hash;
612 info->curr_minor_hash = fname->minor_hash;
613 if (call_filldir(file, ctx, fname))
614 break;
615 next_node:
616 info->curr_node = rb_next(info->curr_node);
617 if (info->curr_node) {
618 fname = rb_entry(info->curr_node, struct fname,
619 rb_hash);
620 info->curr_hash = fname->hash;
621 info->curr_minor_hash = fname->minor_hash;
622 } else {
623 if (info->next_hash == ~0) {
624 ctx->pos = ext4_get_htree_eof(file);
625 break;
626 }
627 info->curr_hash = info->next_hash;
628 info->curr_minor_hash = 0;
629 }
630 }
631finished:
632 info->last_pos = ctx->pos;
633 return ret < 0 ? ret : 0;
634}
635
636static int ext4_release_dir(struct inode *inode, struct file *filp)
637{
638 if (filp->private_data)
639 ext4_htree_free_dir_info(filp->private_data);
640
641 return 0;
642}
643
644int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf,
645 int buf_size)
646{
647 struct ext4_dir_entry_2 *de;
648 int rlen;
649 unsigned int offset = 0;
650 char *top;
651
652 de = (struct ext4_dir_entry_2 *)buf;
653 top = buf + buf_size;
654 while ((char *) de < top) {
655 if (ext4_check_dir_entry(dir, NULL, de, bh,
656 buf, buf_size, offset))
657 return -EFSCORRUPTED;
658 rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
659 de = (struct ext4_dir_entry_2 *)((char *)de + rlen);
660 offset += rlen;
661 }
662 if ((char *) de > top)
663 return -EFSCORRUPTED;
664
665 return 0;
666}
667
668const struct file_operations ext4_dir_operations = {
669 .llseek = ext4_dir_llseek,
670 .read = generic_read_dir,
671 .iterate_shared = ext4_readdir,
672 .unlocked_ioctl = ext4_ioctl,
673#ifdef CONFIG_COMPAT
674 .compat_ioctl = ext4_compat_ioctl,
675#endif
676 .fsync = ext4_sync_file,
677 .release = ext4_release_dir,
678};