Loading...
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
30static 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 */
39static int is_dx_dir(struct inode *inode)
40{
41 struct super_block *sb = inode->i_sb;
42
43 if (ext4_has_feature_dir_index(inode->i_sb) &&
44 ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) ||
45 ((inode->i_size >> sb->s_blocksize_bits) == 1) ||
46 ext4_has_inline_data(inode)))
47 return 1;
48
49 return 0;
50}
51
52/*
53 * Return 0 if the directory entry is OK, and 1 if there is a problem
54 *
55 * Note: this is the opposite of what ext2 and ext3 historically returned...
56 *
57 * bh passed here can be an inode block or a dir data block, depending
58 * on the inode inline data flag.
59 */
60int __ext4_check_dir_entry(const char *function, unsigned int line,
61 struct inode *dir, struct file *filp,
62 struct ext4_dir_entry_2 *de,
63 struct buffer_head *bh, char *buf, int size,
64 unsigned int offset)
65{
66 const char *error_msg = NULL;
67 const int rlen = ext4_rec_len_from_disk(de->rec_len,
68 dir->i_sb->s_blocksize);
69
70 if (unlikely(rlen < EXT4_DIR_REC_LEN(1)))
71 error_msg = "rec_len is smaller than minimal";
72 else if (unlikely(rlen % 4 != 0))
73 error_msg = "rec_len % 4 != 0";
74 else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len)))
75 error_msg = "rec_len is too small for name_len";
76 else if (unlikely(((char *) de - buf) + rlen > size))
77 error_msg = "directory entry across range";
78 else if (unlikely(le32_to_cpu(de->inode) >
79 le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)))
80 error_msg = "inode out of bounds";
81 else
82 return 0;
83
84 if (filp)
85 ext4_error_file(filp, function, line, bh->b_blocknr,
86 "bad entry in directory: %s - offset=%u(%u), "
87 "inode=%u, rec_len=%d, name_len=%d",
88 error_msg, (unsigned) (offset % size),
89 offset, le32_to_cpu(de->inode),
90 rlen, de->name_len);
91 else
92 ext4_error_inode(dir, function, line, bh->b_blocknr,
93 "bad entry in directory: %s - offset=%u(%u), "
94 "inode=%u, rec_len=%d, name_len=%d",
95 error_msg, (unsigned) (offset % size),
96 offset, le32_to_cpu(de->inode),
97 rlen, de->name_len);
98
99 return 1;
100}
101
102static int ext4_readdir(struct file *file, struct dir_context *ctx)
103{
104 unsigned int offset;
105 int i;
106 struct ext4_dir_entry_2 *de;
107 int err;
108 struct inode *inode = file_inode(file);
109 struct super_block *sb = inode->i_sb;
110 struct buffer_head *bh = NULL;
111 int dir_has_error = 0;
112 struct ext4_str fname_crypto_str = {.name = NULL, .len = 0};
113
114 if (ext4_encrypted_inode(inode)) {
115 err = ext4_get_encryption_info(inode);
116 if (err && err != -ENOKEY)
117 return err;
118 }
119
120 if (is_dx_dir(inode)) {
121 err = ext4_dx_readdir(file, ctx);
122 if (err != ERR_BAD_DX_DIR) {
123 return err;
124 }
125 /*
126 * We don't set the inode dirty flag since it's not
127 * critical that it get flushed back to the disk.
128 */
129 ext4_clear_inode_flag(file_inode(file),
130 EXT4_INODE_INDEX);
131 }
132
133 if (ext4_has_inline_data(inode)) {
134 int has_inline_data = 1;
135 err = ext4_read_inline_dir(file, ctx,
136 &has_inline_data);
137 if (has_inline_data)
138 return err;
139 }
140
141 if (ext4_encrypted_inode(inode)) {
142 err = ext4_fname_crypto_alloc_buffer(inode, EXT4_NAME_LEN,
143 &fname_crypto_str);
144 if (err < 0)
145 return err;
146 }
147
148 offset = ctx->pos & (sb->s_blocksize - 1);
149
150 while (ctx->pos < inode->i_size) {
151 struct ext4_map_blocks map;
152
153 map.m_lblk = ctx->pos >> EXT4_BLOCK_SIZE_BITS(sb);
154 map.m_len = 1;
155 err = ext4_map_blocks(NULL, inode, &map, 0);
156 if (err > 0) {
157 pgoff_t index = map.m_pblk >>
158 (PAGE_SHIFT - inode->i_blkbits);
159 if (!ra_has_index(&file->f_ra, index))
160 page_cache_sync_readahead(
161 sb->s_bdev->bd_inode->i_mapping,
162 &file->f_ra, file,
163 index, 1);
164 file->f_ra.prev_pos = (loff_t)index << PAGE_SHIFT;
165 bh = ext4_bread(NULL, inode, map.m_lblk, 0);
166 if (IS_ERR(bh)) {
167 err = PTR_ERR(bh);
168 bh = NULL;
169 goto errout;
170 }
171 }
172
173 if (!bh) {
174 if (!dir_has_error) {
175 EXT4_ERROR_FILE(file, 0,
176 "directory contains a "
177 "hole at offset %llu",
178 (unsigned long long) ctx->pos);
179 dir_has_error = 1;
180 }
181 /* corrupt size? Maybe no more blocks to read */
182 if (ctx->pos > inode->i_blocks << 9)
183 break;
184 ctx->pos += sb->s_blocksize - offset;
185 continue;
186 }
187
188 /* Check the checksum */
189 if (!buffer_verified(bh) &&
190 !ext4_dirent_csum_verify(inode,
191 (struct ext4_dir_entry *)bh->b_data)) {
192 EXT4_ERROR_FILE(file, 0, "directory fails checksum "
193 "at offset %llu",
194 (unsigned long long)ctx->pos);
195 ctx->pos += sb->s_blocksize - offset;
196 brelse(bh);
197 bh = NULL;
198 continue;
199 }
200 set_buffer_verified(bh);
201
202 /* If the dir block has changed since the last call to
203 * readdir(2), then we might be pointing to an invalid
204 * dirent right now. Scan from the start of the block
205 * to make sure. */
206 if (file->f_version != inode->i_version) {
207 for (i = 0; i < sb->s_blocksize && i < offset; ) {
208 de = (struct ext4_dir_entry_2 *)
209 (bh->b_data + i);
210 /* It's too expensive to do a full
211 * dirent test each time round this
212 * loop, but we do have to test at
213 * least that it is non-zero. A
214 * failure will be detected in the
215 * dirent test below. */
216 if (ext4_rec_len_from_disk(de->rec_len,
217 sb->s_blocksize) < EXT4_DIR_REC_LEN(1))
218 break;
219 i += ext4_rec_len_from_disk(de->rec_len,
220 sb->s_blocksize);
221 }
222 offset = i;
223 ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1))
224 | offset;
225 file->f_version = inode->i_version;
226 }
227
228 while (ctx->pos < inode->i_size
229 && offset < sb->s_blocksize) {
230 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
231 if (ext4_check_dir_entry(inode, file, de, bh,
232 bh->b_data, bh->b_size,
233 offset)) {
234 /*
235 * On error, skip to the next block
236 */
237 ctx->pos = (ctx->pos |
238 (sb->s_blocksize - 1)) + 1;
239 break;
240 }
241 offset += ext4_rec_len_from_disk(de->rec_len,
242 sb->s_blocksize);
243 if (le32_to_cpu(de->inode)) {
244 if (!ext4_encrypted_inode(inode)) {
245 if (!dir_emit(ctx, de->name,
246 de->name_len,
247 le32_to_cpu(de->inode),
248 get_dtype(sb, de->file_type)))
249 goto done;
250 } else {
251 int save_len = fname_crypto_str.len;
252
253 /* Directory is encrypted */
254 err = ext4_fname_disk_to_usr(inode,
255 NULL, de, &fname_crypto_str);
256 fname_crypto_str.len = save_len;
257 if (err < 0)
258 goto errout;
259 if (!dir_emit(ctx,
260 fname_crypto_str.name, err,
261 le32_to_cpu(de->inode),
262 get_dtype(sb, de->file_type)))
263 goto done;
264 }
265 }
266 ctx->pos += ext4_rec_len_from_disk(de->rec_len,
267 sb->s_blocksize);
268 }
269 if ((ctx->pos < inode->i_size) && !dir_relax(inode))
270 goto done;
271 brelse(bh);
272 bh = NULL;
273 offset = 0;
274 }
275done:
276 err = 0;
277errout:
278#ifdef CONFIG_EXT4_FS_ENCRYPTION
279 ext4_fname_crypto_free_buffer(&fname_crypto_str);
280#endif
281 brelse(bh);
282 return err;
283}
284
285static inline int is_32bit_api(void)
286{
287#ifdef CONFIG_COMPAT
288 return in_compat_syscall();
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 */
303static 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
312static 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
321static 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 */
333static 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 */
354static 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 */
371struct 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 */
386static 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
401static 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
414void 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 */
427int 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 */
490static 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
517static 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 }
599finished:
600 info->last_pos = ctx->pos;
601 return 0;
602}
603
604static int ext4_dir_open(struct inode * inode, struct file * filp)
605{
606 if (ext4_encrypted_inode(inode))
607 return ext4_get_encryption_info(inode) ? -EACCES : 0;
608 return 0;
609}
610
611static int ext4_release_dir(struct inode *inode, struct file *filp)
612{
613 if (filp->private_data)
614 ext4_htree_free_dir_info(filp->private_data);
615
616 return 0;
617}
618
619int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf,
620 int buf_size)
621{
622 struct ext4_dir_entry_2 *de;
623 int nlen, rlen;
624 unsigned int offset = 0;
625 char *top;
626
627 de = (struct ext4_dir_entry_2 *)buf;
628 top = buf + buf_size;
629 while ((char *) de < top) {
630 if (ext4_check_dir_entry(dir, NULL, de, bh,
631 buf, buf_size, offset))
632 return -EFSCORRUPTED;
633 nlen = EXT4_DIR_REC_LEN(de->name_len);
634 rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
635 de = (struct ext4_dir_entry_2 *)((char *)de + rlen);
636 offset += rlen;
637 }
638 if ((char *) de > top)
639 return -EFSCORRUPTED;
640
641 return 0;
642}
643
644const struct file_operations ext4_dir_operations = {
645 .llseek = ext4_dir_llseek,
646 .read = generic_read_dir,
647 .iterate = ext4_readdir,
648 .unlocked_ioctl = ext4_ioctl,
649#ifdef CONFIG_COMPAT
650 .compat_ioctl = ext4_compat_ioctl,
651#endif
652 .fsync = ext4_sync_file,
653 .open = ext4_dir_open,
654 .release = ext4_release_dir,
655};
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 }
307done:
308 err = 0;
309errout:
310 fscrypt_fname_free_buffer(&fstr);
311 brelse(bh);
312 return err;
313}
314
315static inline int is_32bit_api(void)
316{
317#ifdef CONFIG_COMPAT
318 return in_compat_syscall();
319#else
320 return (BITS_PER_LONG == 32);
321#endif
322}
323
324/*
325 * These functions convert from the major/minor hash to an f_pos
326 * value for dx directories
327 *
328 * Upper layer (for example NFS) should specify FMODE_32BITHASH or
329 * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted
330 * directly on both 32-bit and 64-bit nodes, under such case, neither
331 * FMODE_32BITHASH nor FMODE_64BITHASH is specified.
332 */
333static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor)
334{
335 if ((filp->f_mode & FMODE_32BITHASH) ||
336 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
337 return major >> 1;
338 else
339 return ((__u64)(major >> 1) << 32) | (__u64)minor;
340}
341
342static inline __u32 pos2maj_hash(struct file *filp, loff_t pos)
343{
344 if ((filp->f_mode & FMODE_32BITHASH) ||
345 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
346 return (pos << 1) & 0xffffffff;
347 else
348 return ((pos >> 32) << 1) & 0xffffffff;
349}
350
351static inline __u32 pos2min_hash(struct file *filp, loff_t pos)
352{
353 if ((filp->f_mode & FMODE_32BITHASH) ||
354 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
355 return 0;
356 else
357 return pos & 0xffffffff;
358}
359
360/*
361 * Return 32- or 64-bit end-of-file for dx directories
362 */
363static inline loff_t ext4_get_htree_eof(struct file *filp)
364{
365 if ((filp->f_mode & FMODE_32BITHASH) ||
366 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
367 return EXT4_HTREE_EOF_32BIT;
368 else
369 return EXT4_HTREE_EOF_64BIT;
370}
371
372
373/*
374 * ext4_dir_llseek() calls generic_file_llseek_size to handle htree
375 * directories, where the "offset" is in terms of the filename hash
376 * value instead of the byte offset.
377 *
378 * Because we may return a 64-bit hash that is well beyond offset limits,
379 * we need to pass the max hash as the maximum allowable offset in
380 * the htree directory case.
381 *
382 * For non-htree, ext4_llseek already chooses the proper max offset.
383 */
384static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence)
385{
386 struct inode *inode = file->f_mapping->host;
387 int dx_dir = is_dx_dir(inode);
388 loff_t ret, htree_max = ext4_get_htree_eof(file);
389
390 if (likely(dx_dir))
391 ret = generic_file_llseek_size(file, offset, whence,
392 htree_max, htree_max);
393 else
394 ret = ext4_llseek(file, offset, whence);
395 file->f_version = inode_peek_iversion(inode) - 1;
396 return ret;
397}
398
399/*
400 * This structure holds the nodes of the red-black tree used to store
401 * the directory entry in hash order.
402 */
403struct fname {
404 __u32 hash;
405 __u32 minor_hash;
406 struct rb_node rb_hash;
407 struct fname *next;
408 __u32 inode;
409 __u8 name_len;
410 __u8 file_type;
411 char name[];
412};
413
414/*
415 * This function implements a non-recursive way of freeing all of the
416 * nodes in the red-black tree.
417 */
418static void free_rb_tree_fname(struct rb_root *root)
419{
420 struct fname *fname, *next;
421
422 rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash)
423 while (fname) {
424 struct fname *old = fname;
425 fname = fname->next;
426 kfree(old);
427 }
428
429 *root = RB_ROOT;
430}
431
432
433static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp,
434 loff_t pos)
435{
436 struct dir_private_info *p;
437
438 p = kzalloc(sizeof(*p), GFP_KERNEL);
439 if (!p)
440 return NULL;
441 p->curr_hash = pos2maj_hash(filp, pos);
442 p->curr_minor_hash = pos2min_hash(filp, pos);
443 return p;
444}
445
446void ext4_htree_free_dir_info(struct dir_private_info *p)
447{
448 free_rb_tree_fname(&p->root);
449 kfree(p);
450}
451
452/*
453 * Given a directory entry, enter it into the fname rb tree.
454 *
455 * When filename encryption is enabled, the dirent will hold the
456 * encrypted filename, while the htree will hold decrypted filename.
457 * The decrypted filename is passed in via ent_name. parameter.
458 */
459int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
460 __u32 minor_hash,
461 struct ext4_dir_entry_2 *dirent,
462 struct fscrypt_str *ent_name)
463{
464 struct rb_node **p, *parent = NULL;
465 struct fname *fname, *new_fn;
466 struct dir_private_info *info;
467 int len;
468
469 info = dir_file->private_data;
470 p = &info->root.rb_node;
471
472 /* Create and allocate the fname structure */
473 len = sizeof(struct fname) + ent_name->len + 1;
474 new_fn = kzalloc(len, GFP_KERNEL);
475 if (!new_fn)
476 return -ENOMEM;
477 new_fn->hash = hash;
478 new_fn->minor_hash = minor_hash;
479 new_fn->inode = le32_to_cpu(dirent->inode);
480 new_fn->name_len = ent_name->len;
481 new_fn->file_type = dirent->file_type;
482 memcpy(new_fn->name, ent_name->name, ent_name->len);
483
484 while (*p) {
485 parent = *p;
486 fname = rb_entry(parent, struct fname, rb_hash);
487
488 /*
489 * If the hash and minor hash match up, then we put
490 * them on a linked list. This rarely happens...
491 */
492 if ((new_fn->hash == fname->hash) &&
493 (new_fn->minor_hash == fname->minor_hash)) {
494 new_fn->next = fname->next;
495 fname->next = new_fn;
496 return 0;
497 }
498
499 if (new_fn->hash < fname->hash)
500 p = &(*p)->rb_left;
501 else if (new_fn->hash > fname->hash)
502 p = &(*p)->rb_right;
503 else if (new_fn->minor_hash < fname->minor_hash)
504 p = &(*p)->rb_left;
505 else /* if (new_fn->minor_hash > fname->minor_hash) */
506 p = &(*p)->rb_right;
507 }
508
509 rb_link_node(&new_fn->rb_hash, parent, p);
510 rb_insert_color(&new_fn->rb_hash, &info->root);
511 return 0;
512}
513
514
515
516/*
517 * This is a helper function for ext4_dx_readdir. It calls filldir
518 * for all entries on the fname linked list. (Normally there is only
519 * one entry on the linked list, unless there are 62 bit hash collisions.)
520 */
521static int call_filldir(struct file *file, struct dir_context *ctx,
522 struct fname *fname)
523{
524 struct dir_private_info *info = file->private_data;
525 struct inode *inode = file_inode(file);
526 struct super_block *sb = inode->i_sb;
527
528 if (!fname) {
529 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: "
530 "called with null fname?!?", __func__, __LINE__,
531 inode->i_ino, current->comm);
532 return 0;
533 }
534 ctx->pos = hash2pos(file, fname->hash, fname->minor_hash);
535 while (fname) {
536 if (!dir_emit(ctx, fname->name,
537 fname->name_len,
538 fname->inode,
539 get_dtype(sb, fname->file_type))) {
540 info->extra_fname = fname;
541 return 1;
542 }
543 fname = fname->next;
544 }
545 return 0;
546}
547
548static int ext4_dx_readdir(struct file *file, struct dir_context *ctx)
549{
550 struct dir_private_info *info = file->private_data;
551 struct inode *inode = file_inode(file);
552 struct fname *fname;
553 int ret = 0;
554
555 if (!info) {
556 info = ext4_htree_create_dir_info(file, ctx->pos);
557 if (!info)
558 return -ENOMEM;
559 file->private_data = info;
560 }
561
562 if (ctx->pos == ext4_get_htree_eof(file))
563 return 0; /* EOF */
564
565 /* Some one has messed with f_pos; reset the world */
566 if (info->last_pos != ctx->pos) {
567 free_rb_tree_fname(&info->root);
568 info->curr_node = NULL;
569 info->extra_fname = NULL;
570 info->curr_hash = pos2maj_hash(file, ctx->pos);
571 info->curr_minor_hash = pos2min_hash(file, ctx->pos);
572 }
573
574 /*
575 * If there are any leftover names on the hash collision
576 * chain, return them first.
577 */
578 if (info->extra_fname) {
579 if (call_filldir(file, ctx, info->extra_fname))
580 goto finished;
581 info->extra_fname = NULL;
582 goto next_node;
583 } else if (!info->curr_node)
584 info->curr_node = rb_first(&info->root);
585
586 while (1) {
587 /*
588 * Fill the rbtree if we have no more entries,
589 * or the inode has changed since we last read in the
590 * cached entries.
591 */
592 if ((!info->curr_node) ||
593 !inode_eq_iversion(inode, file->f_version)) {
594 info->curr_node = NULL;
595 free_rb_tree_fname(&info->root);
596 file->f_version = inode_query_iversion(inode);
597 ret = ext4_htree_fill_tree(file, info->curr_hash,
598 info->curr_minor_hash,
599 &info->next_hash);
600 if (ret < 0)
601 goto finished;
602 if (ret == 0) {
603 ctx->pos = ext4_get_htree_eof(file);
604 break;
605 }
606 info->curr_node = rb_first(&info->root);
607 }
608
609 fname = rb_entry(info->curr_node, struct fname, rb_hash);
610 info->curr_hash = fname->hash;
611 info->curr_minor_hash = fname->minor_hash;
612 if (call_filldir(file, ctx, fname))
613 break;
614 next_node:
615 info->curr_node = rb_next(info->curr_node);
616 if (info->curr_node) {
617 fname = rb_entry(info->curr_node, struct fname,
618 rb_hash);
619 info->curr_hash = fname->hash;
620 info->curr_minor_hash = fname->minor_hash;
621 } else {
622 if (info->next_hash == ~0) {
623 ctx->pos = ext4_get_htree_eof(file);
624 break;
625 }
626 info->curr_hash = info->next_hash;
627 info->curr_minor_hash = 0;
628 }
629 }
630finished:
631 info->last_pos = ctx->pos;
632 return ret < 0 ? ret : 0;
633}
634
635static int ext4_release_dir(struct inode *inode, struct file *filp)
636{
637 if (filp->private_data)
638 ext4_htree_free_dir_info(filp->private_data);
639
640 return 0;
641}
642
643int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf,
644 int buf_size)
645{
646 struct ext4_dir_entry_2 *de;
647 int rlen;
648 unsigned int offset = 0;
649 char *top;
650
651 de = buf;
652 top = buf + buf_size;
653 while ((char *) de < top) {
654 if (ext4_check_dir_entry(dir, NULL, de, bh,
655 buf, buf_size, offset))
656 return -EFSCORRUPTED;
657 rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
658 de = (struct ext4_dir_entry_2 *)((char *)de + rlen);
659 offset += rlen;
660 }
661 if ((char *) de > top)
662 return -EFSCORRUPTED;
663
664 return 0;
665}
666
667const struct file_operations ext4_dir_operations = {
668 .llseek = ext4_dir_llseek,
669 .read = generic_read_dir,
670 .iterate_shared = ext4_readdir,
671 .unlocked_ioctl = ext4_ioctl,
672#ifdef CONFIG_COMPAT
673 .compat_ioctl = ext4_compat_ioctl,
674#endif
675 .fsync = ext4_sync_file,
676 .release = ext4_release_dir,
677};