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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 
33 static 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  */
is_dx_dir(struct inode * inode)45 static 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 
58 /*
59  * Return 0 if the directory entry is OK, and 1 if there is a problem
60  *
61  * Note: this is the opposite of what ext2 and ext3 historically returned...
62  *
63  * bh passed here can be an inode block or a dir data block, depending
64  * on the inode inline data flag.
65  */
__ext4_check_dir_entry(const char * function,unsigned int line,struct inode * dir,struct file * filp,struct ext4_dir_entry_2 * de,struct buffer_head * bh,char * buf,int size,unsigned int offset)66 int __ext4_check_dir_entry(const char *function, unsigned int line,
67 			   struct inode *dir, struct file *filp,
68 			   struct ext4_dir_entry_2 *de,
69 			   struct buffer_head *bh, char *buf, int size,
70 			   unsigned int offset)
71 {
72 	const char *error_msg = NULL;
73 	const int rlen = ext4_rec_len_from_disk(de->rec_len,
74 						dir->i_sb->s_blocksize);
75 
76 	if (unlikely(rlen < EXT4_DIR_REC_LEN(1)))
77 		error_msg = "rec_len is smaller than minimal";
78 	else if (unlikely(rlen % 4 != 0))
79 		error_msg = "rec_len % 4 != 0";
80 	else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len)))
81 		error_msg = "rec_len is too small for name_len";
82 	else if (unlikely(((char *) de - buf) + rlen > size))
83 		error_msg = "directory entry overrun";
84 	else if (unlikely(((char *) de - buf) + rlen >
85 			  size - EXT4_DIR_REC_LEN(1) &&
86 			  ((char *) de - buf) + rlen != size)) {
87 		error_msg = "directory entry too close to block end";
88 	}
89 	else if (unlikely(le32_to_cpu(de->inode) >
90 			le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)))
91 		error_msg = "inode out of bounds";
92 	else
93 		return 0;
94 
95 	if (filp)
96 		ext4_error_file(filp, function, line, bh->b_blocknr,
97 				"bad entry in directory: %s - offset=%u, "
98 				"inode=%u, rec_len=%d, name_len=%d, size=%d",
99 				error_msg, offset, le32_to_cpu(de->inode),
100 				rlen, de->name_len, size);
101 	else
102 		ext4_error_inode(dir, function, line, bh->b_blocknr,
103 				"bad entry in directory: %s - offset=%u, "
104 				"inode=%u, rec_len=%d, name_len=%d, size=%d",
105 				 error_msg, offset, le32_to_cpu(de->inode),
106 				 rlen, de->name_len, size);
107 
108 	return 1;
109 }
110 
ext4_readdir(struct file * file,struct dir_context * ctx)111 static int ext4_readdir(struct file *file, struct dir_context *ctx)
112 {
113 	unsigned int offset;
114 	int i;
115 	struct ext4_dir_entry_2 *de;
116 	int err;
117 	struct inode *inode = file_inode(file);
118 	struct super_block *sb = inode->i_sb;
119 	struct buffer_head *bh = NULL;
120 	struct fscrypt_str fstr = FSTR_INIT(NULL, 0);
121 
122 	if (IS_ENCRYPTED(inode)) {
123 		err = fscrypt_get_encryption_info(inode);
124 		if (err && err != -ENOKEY)
125 			return err;
126 	}
127 
128 	if (is_dx_dir(inode)) {
129 		err = ext4_dx_readdir(file, ctx);
130 		if (err != ERR_BAD_DX_DIR) {
131 			return err;
132 		}
133 		/*
134 		 * We don't set the inode dirty flag since it's not
135 		 * critical that it get flushed back to the disk.
136 		 */
137 		ext4_clear_inode_flag(file_inode(file),
138 				      EXT4_INODE_INDEX);
139 	}
140 
141 	if (ext4_has_inline_data(inode)) {
142 		int has_inline_data = 1;
143 		err = ext4_read_inline_dir(file, ctx,
144 					   &has_inline_data);
145 		if (has_inline_data)
146 			return err;
147 	}
148 
149 	if (IS_ENCRYPTED(inode)) {
150 		err = fscrypt_fname_alloc_buffer(inode, EXT4_NAME_LEN, &fstr);
151 		if (err < 0)
152 			return err;
153 	}
154 
155 	while (ctx->pos < inode->i_size) {
156 		struct ext4_map_blocks map;
157 
158 		if (fatal_signal_pending(current)) {
159 			err = -ERESTARTSYS;
160 			goto errout;
161 		}
162 		cond_resched();
163 		offset = ctx->pos & (sb->s_blocksize - 1);
164 		map.m_lblk = ctx->pos >> EXT4_BLOCK_SIZE_BITS(sb);
165 		map.m_len = 1;
166 		err = ext4_map_blocks(NULL, inode, &map, 0);
167 		if (err == 0) {
168 			/* m_len should never be zero but let's avoid
169 			 * an infinite loop if it somehow is */
170 			if (map.m_len == 0)
171 				map.m_len = 1;
172 			ctx->pos += map.m_len * sb->s_blocksize;
173 			continue;
174 		}
175 		if (err > 0) {
176 			pgoff_t index = map.m_pblk >>
177 					(PAGE_SHIFT - inode->i_blkbits);
178 			if (!ra_has_index(&file->f_ra, index))
179 				page_cache_sync_readahead(
180 					sb->s_bdev->bd_inode->i_mapping,
181 					&file->f_ra, file,
182 					index, 1);
183 			file->f_ra.prev_pos = (loff_t)index << PAGE_SHIFT;
184 			bh = ext4_bread(NULL, inode, map.m_lblk, 0);
185 			if (IS_ERR(bh)) {
186 				err = PTR_ERR(bh);
187 				bh = NULL;
188 				goto errout;
189 			}
190 		}
191 
192 		if (!bh) {
193 			/* corrupt size?  Maybe no more blocks to read */
194 			if (ctx->pos > inode->i_blocks << 9)
195 				break;
196 			ctx->pos += sb->s_blocksize - offset;
197 			continue;
198 		}
199 
200 		/* Check the checksum */
201 		if (!buffer_verified(bh) &&
202 		    !ext4_dirblock_csum_verify(inode, bh)) {
203 			EXT4_ERROR_FILE(file, 0, "directory fails checksum "
204 					"at offset %llu",
205 					(unsigned long long)ctx->pos);
206 			ctx->pos += sb->s_blocksize - offset;
207 			brelse(bh);
208 			bh = NULL;
209 			continue;
210 		}
211 		set_buffer_verified(bh);
212 
213 		/* If the dir block has changed since the last call to
214 		 * readdir(2), then we might be pointing to an invalid
215 		 * dirent right now.  Scan from the start of the block
216 		 * to make sure. */
217 		if (!inode_eq_iversion(inode, file->f_version)) {
218 			for (i = 0; i < sb->s_blocksize && i < offset; ) {
219 				de = (struct ext4_dir_entry_2 *)
220 					(bh->b_data + i);
221 				/* It's too expensive to do a full
222 				 * dirent test each time round this
223 				 * loop, but we do have to test at
224 				 * least that it is non-zero.  A
225 				 * failure will be detected in the
226 				 * dirent test below. */
227 				if (ext4_rec_len_from_disk(de->rec_len,
228 					sb->s_blocksize) < EXT4_DIR_REC_LEN(1))
229 					break;
230 				i += ext4_rec_len_from_disk(de->rec_len,
231 							    sb->s_blocksize);
232 			}
233 			offset = i;
234 			ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1))
235 				| offset;
236 			file->f_version = inode_query_iversion(inode);
237 		}
238 
239 		while (ctx->pos < inode->i_size
240 		       && offset < sb->s_blocksize) {
241 			de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
242 			if (ext4_check_dir_entry(inode, file, de, bh,
243 						 bh->b_data, bh->b_size,
244 						 offset)) {
245 				/*
246 				 * On error, skip to the next block
247 				 */
248 				ctx->pos = (ctx->pos |
249 						(sb->s_blocksize - 1)) + 1;
250 				break;
251 			}
252 			offset += ext4_rec_len_from_disk(de->rec_len,
253 					sb->s_blocksize);
254 			if (le32_to_cpu(de->inode)) {
255 				if (!IS_ENCRYPTED(inode)) {
256 					if (!dir_emit(ctx, de->name,
257 					    de->name_len,
258 					    le32_to_cpu(de->inode),
259 					    get_dtype(sb, de->file_type)))
260 						goto done;
261 				} else {
262 					int save_len = fstr.len;
263 					struct fscrypt_str de_name =
264 							FSTR_INIT(de->name,
265 								de->name_len);
266 
267 					/* Directory is encrypted */
268 					err = fscrypt_fname_disk_to_usr(inode,
269 						0, 0, &de_name, &fstr);
270 					de_name = fstr;
271 					fstr.len = save_len;
272 					if (err)
273 						goto errout;
274 					if (!dir_emit(ctx,
275 					    de_name.name, de_name.len,
276 					    le32_to_cpu(de->inode),
277 					    get_dtype(sb, de->file_type)))
278 						goto done;
279 				}
280 			}
281 			ctx->pos += ext4_rec_len_from_disk(de->rec_len,
282 						sb->s_blocksize);
283 		}
284 		if ((ctx->pos < inode->i_size) && !dir_relax_shared(inode))
285 			goto done;
286 		brelse(bh);
287 		bh = NULL;
288 		offset = 0;
289 	}
290 done:
291 	err = 0;
292 errout:
293 	fscrypt_fname_free_buffer(&fstr);
294 	brelse(bh);
295 	return err;
296 }
297 
is_32bit_api(void)298 static inline int is_32bit_api(void)
299 {
300 #ifdef CONFIG_COMPAT
301 	return in_compat_syscall();
302 #else
303 	return (BITS_PER_LONG == 32);
304 #endif
305 }
306 
307 /*
308  * These functions convert from the major/minor hash to an f_pos
309  * value for dx directories
310  *
311  * Upper layer (for example NFS) should specify FMODE_32BITHASH or
312  * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted
313  * directly on both 32-bit and 64-bit nodes, under such case, neither
314  * FMODE_32BITHASH nor FMODE_64BITHASH is specified.
315  */
hash2pos(struct file * filp,__u32 major,__u32 minor)316 static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor)
317 {
318 	if ((filp->f_mode & FMODE_32BITHASH) ||
319 	    (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
320 		return major >> 1;
321 	else
322 		return ((__u64)(major >> 1) << 32) | (__u64)minor;
323 }
324 
pos2maj_hash(struct file * filp,loff_t pos)325 static inline __u32 pos2maj_hash(struct file *filp, loff_t pos)
326 {
327 	if ((filp->f_mode & FMODE_32BITHASH) ||
328 	    (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
329 		return (pos << 1) & 0xffffffff;
330 	else
331 		return ((pos >> 32) << 1) & 0xffffffff;
332 }
333 
pos2min_hash(struct file * filp,loff_t pos)334 static inline __u32 pos2min_hash(struct file *filp, loff_t pos)
335 {
336 	if ((filp->f_mode & FMODE_32BITHASH) ||
337 	    (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
338 		return 0;
339 	else
340 		return pos & 0xffffffff;
341 }
342 
343 /*
344  * Return 32- or 64-bit end-of-file for dx directories
345  */
ext4_get_htree_eof(struct file * filp)346 static inline loff_t ext4_get_htree_eof(struct file *filp)
347 {
348 	if ((filp->f_mode & FMODE_32BITHASH) ||
349 	    (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
350 		return EXT4_HTREE_EOF_32BIT;
351 	else
352 		return EXT4_HTREE_EOF_64BIT;
353 }
354 
355 
356 /*
357  * ext4_dir_llseek() calls generic_file_llseek_size to handle htree
358  * directories, where the "offset" is in terms of the filename hash
359  * value instead of the byte offset.
360  *
361  * Because we may return a 64-bit hash that is well beyond offset limits,
362  * we need to pass the max hash as the maximum allowable offset in
363  * the htree directory case.
364  *
365  * For non-htree, ext4_llseek already chooses the proper max offset.
366  */
ext4_dir_llseek(struct file * file,loff_t offset,int whence)367 static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence)
368 {
369 	struct inode *inode = file->f_mapping->host;
370 	int dx_dir = is_dx_dir(inode);
371 	loff_t ret, htree_max = ext4_get_htree_eof(file);
372 
373 	if (likely(dx_dir))
374 		ret = generic_file_llseek_size(file, offset, whence,
375 						    htree_max, htree_max);
376 	else
377 		ret = ext4_llseek(file, offset, whence);
378 	file->f_version = inode_peek_iversion(inode) - 1;
379 	return ret;
380 }
381 
382 /*
383  * This structure holds the nodes of the red-black tree used to store
384  * the directory entry in hash order.
385  */
386 struct fname {
387 	__u32		hash;
388 	__u32		minor_hash;
389 	struct rb_node	rb_hash;
390 	struct fname	*next;
391 	__u32		inode;
392 	__u8		name_len;
393 	__u8		file_type;
394 	char		name[0];
395 };
396 
397 /*
398  * This functoin implements a non-recursive way of freeing all of the
399  * nodes in the red-black tree.
400  */
free_rb_tree_fname(struct rb_root * root)401 static void free_rb_tree_fname(struct rb_root *root)
402 {
403 	struct fname *fname, *next;
404 
405 	rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash)
406 		while (fname) {
407 			struct fname *old = fname;
408 			fname = fname->next;
409 			kfree(old);
410 		}
411 
412 	*root = RB_ROOT;
413 }
414 
415 
ext4_htree_create_dir_info(struct file * filp,loff_t pos)416 static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp,
417 							   loff_t pos)
418 {
419 	struct dir_private_info *p;
420 
421 	p = kzalloc(sizeof(*p), GFP_KERNEL);
422 	if (!p)
423 		return NULL;
424 	p->curr_hash = pos2maj_hash(filp, pos);
425 	p->curr_minor_hash = pos2min_hash(filp, pos);
426 	return p;
427 }
428 
ext4_htree_free_dir_info(struct dir_private_info * p)429 void ext4_htree_free_dir_info(struct dir_private_info *p)
430 {
431 	free_rb_tree_fname(&p->root);
432 	kfree(p);
433 }
434 
435 /*
436  * Given a directory entry, enter it into the fname rb tree.
437  *
438  * When filename encryption is enabled, the dirent will hold the
439  * encrypted filename, while the htree will hold decrypted filename.
440  * The decrypted filename is passed in via ent_name.  parameter.
441  */
ext4_htree_store_dirent(struct file * dir_file,__u32 hash,__u32 minor_hash,struct ext4_dir_entry_2 * dirent,struct fscrypt_str * ent_name)442 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
443 			     __u32 minor_hash,
444 			    struct ext4_dir_entry_2 *dirent,
445 			    struct fscrypt_str *ent_name)
446 {
447 	struct rb_node **p, *parent = NULL;
448 	struct fname *fname, *new_fn;
449 	struct dir_private_info *info;
450 	int len;
451 
452 	info = dir_file->private_data;
453 	p = &info->root.rb_node;
454 
455 	/* Create and allocate the fname structure */
456 	len = sizeof(struct fname) + ent_name->len + 1;
457 	new_fn = kzalloc(len, GFP_KERNEL);
458 	if (!new_fn)
459 		return -ENOMEM;
460 	new_fn->hash = hash;
461 	new_fn->minor_hash = minor_hash;
462 	new_fn->inode = le32_to_cpu(dirent->inode);
463 	new_fn->name_len = ent_name->len;
464 	new_fn->file_type = dirent->file_type;
465 	memcpy(new_fn->name, ent_name->name, ent_name->len);
466 	new_fn->name[ent_name->len] = 0;
467 
468 	while (*p) {
469 		parent = *p;
470 		fname = rb_entry(parent, struct fname, rb_hash);
471 
472 		/*
473 		 * If the hash and minor hash match up, then we put
474 		 * them on a linked list.  This rarely happens...
475 		 */
476 		if ((new_fn->hash == fname->hash) &&
477 		    (new_fn->minor_hash == fname->minor_hash)) {
478 			new_fn->next = fname->next;
479 			fname->next = new_fn;
480 			return 0;
481 		}
482 
483 		if (new_fn->hash < fname->hash)
484 			p = &(*p)->rb_left;
485 		else if (new_fn->hash > fname->hash)
486 			p = &(*p)->rb_right;
487 		else if (new_fn->minor_hash < fname->minor_hash)
488 			p = &(*p)->rb_left;
489 		else /* if (new_fn->minor_hash > fname->minor_hash) */
490 			p = &(*p)->rb_right;
491 	}
492 
493 	rb_link_node(&new_fn->rb_hash, parent, p);
494 	rb_insert_color(&new_fn->rb_hash, &info->root);
495 	return 0;
496 }
497 
498 
499 
500 /*
501  * This is a helper function for ext4_dx_readdir.  It calls filldir
502  * for all entres on the fname linked list.  (Normally there is only
503  * one entry on the linked list, unless there are 62 bit hash collisions.)
504  */
call_filldir(struct file * file,struct dir_context * ctx,struct fname * fname)505 static int call_filldir(struct file *file, struct dir_context *ctx,
506 			struct fname *fname)
507 {
508 	struct dir_private_info *info = file->private_data;
509 	struct inode *inode = file_inode(file);
510 	struct super_block *sb = inode->i_sb;
511 
512 	if (!fname) {
513 		ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: "
514 			 "called with null fname?!?", __func__, __LINE__,
515 			 inode->i_ino, current->comm);
516 		return 0;
517 	}
518 	ctx->pos = hash2pos(file, fname->hash, fname->minor_hash);
519 	while (fname) {
520 		if (!dir_emit(ctx, fname->name,
521 				fname->name_len,
522 				fname->inode,
523 				get_dtype(sb, fname->file_type))) {
524 			info->extra_fname = fname;
525 			return 1;
526 		}
527 		fname = fname->next;
528 	}
529 	return 0;
530 }
531 
ext4_dx_readdir(struct file * file,struct dir_context * ctx)532 static int ext4_dx_readdir(struct file *file, struct dir_context *ctx)
533 {
534 	struct dir_private_info *info = file->private_data;
535 	struct inode *inode = file_inode(file);
536 	struct fname *fname;
537 	int	ret;
538 
539 	if (!info) {
540 		info = ext4_htree_create_dir_info(file, ctx->pos);
541 		if (!info)
542 			return -ENOMEM;
543 		file->private_data = info;
544 	}
545 
546 	if (ctx->pos == ext4_get_htree_eof(file))
547 		return 0;	/* EOF */
548 
549 	/* Some one has messed with f_pos; reset the world */
550 	if (info->last_pos != ctx->pos) {
551 		free_rb_tree_fname(&info->root);
552 		info->curr_node = NULL;
553 		info->extra_fname = NULL;
554 		info->curr_hash = pos2maj_hash(file, ctx->pos);
555 		info->curr_minor_hash = pos2min_hash(file, ctx->pos);
556 	}
557 
558 	/*
559 	 * If there are any leftover names on the hash collision
560 	 * chain, return them first.
561 	 */
562 	if (info->extra_fname) {
563 		if (call_filldir(file, ctx, info->extra_fname))
564 			goto finished;
565 		info->extra_fname = NULL;
566 		goto next_node;
567 	} else if (!info->curr_node)
568 		info->curr_node = rb_first(&info->root);
569 
570 	while (1) {
571 		/*
572 		 * Fill the rbtree if we have no more entries,
573 		 * or the inode has changed since we last read in the
574 		 * cached entries.
575 		 */
576 		if ((!info->curr_node) ||
577 		    !inode_eq_iversion(inode, file->f_version)) {
578 			info->curr_node = NULL;
579 			free_rb_tree_fname(&info->root);
580 			file->f_version = inode_query_iversion(inode);
581 			ret = ext4_htree_fill_tree(file, info->curr_hash,
582 						   info->curr_minor_hash,
583 						   &info->next_hash);
584 			if (ret < 0)
585 				return ret;
586 			if (ret == 0) {
587 				ctx->pos = ext4_get_htree_eof(file);
588 				break;
589 			}
590 			info->curr_node = rb_first(&info->root);
591 		}
592 
593 		fname = rb_entry(info->curr_node, struct fname, rb_hash);
594 		info->curr_hash = fname->hash;
595 		info->curr_minor_hash = fname->minor_hash;
596 		if (call_filldir(file, ctx, fname))
597 			break;
598 	next_node:
599 		info->curr_node = rb_next(info->curr_node);
600 		if (info->curr_node) {
601 			fname = rb_entry(info->curr_node, struct fname,
602 					 rb_hash);
603 			info->curr_hash = fname->hash;
604 			info->curr_minor_hash = fname->minor_hash;
605 		} else {
606 			if (info->next_hash == ~0) {
607 				ctx->pos = ext4_get_htree_eof(file);
608 				break;
609 			}
610 			info->curr_hash = info->next_hash;
611 			info->curr_minor_hash = 0;
612 		}
613 	}
614 finished:
615 	info->last_pos = ctx->pos;
616 	return 0;
617 }
618 
ext4_dir_open(struct inode * inode,struct file * filp)619 static int ext4_dir_open(struct inode * inode, struct file * filp)
620 {
621 	if (IS_ENCRYPTED(inode))
622 		return fscrypt_get_encryption_info(inode) ? -EACCES : 0;
623 	return 0;
624 }
625 
ext4_release_dir(struct inode * inode,struct file * filp)626 static int ext4_release_dir(struct inode *inode, struct file *filp)
627 {
628 	if (filp->private_data)
629 		ext4_htree_free_dir_info(filp->private_data);
630 
631 	return 0;
632 }
633 
ext4_check_all_de(struct inode * dir,struct buffer_head * bh,void * buf,int buf_size)634 int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf,
635 		      int buf_size)
636 {
637 	struct ext4_dir_entry_2 *de;
638 	int rlen;
639 	unsigned int offset = 0;
640 	char *top;
641 
642 	de = (struct ext4_dir_entry_2 *)buf;
643 	top = buf + buf_size;
644 	while ((char *) de < top) {
645 		if (ext4_check_dir_entry(dir, NULL, de, bh,
646 					 buf, buf_size, offset))
647 			return -EFSCORRUPTED;
648 		rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
649 		de = (struct ext4_dir_entry_2 *)((char *)de + rlen);
650 		offset += rlen;
651 	}
652 	if ((char *) de > top)
653 		return -EFSCORRUPTED;
654 
655 	return 0;
656 }
657 
658 const struct file_operations ext4_dir_operations = {
659 	.llseek		= ext4_dir_llseek,
660 	.read		= generic_read_dir,
661 	.iterate_shared	= ext4_readdir,
662 	.unlocked_ioctl = ext4_ioctl,
663 #ifdef CONFIG_COMPAT
664 	.compat_ioctl	= ext4_compat_ioctl,
665 #endif
666 	.fsync		= ext4_sync_file,
667 	.open		= ext4_dir_open,
668 	.release	= ext4_release_dir,
669 };
670 
671 #ifdef CONFIG_UNICODE
ext4_d_compare(const struct dentry * dentry,unsigned int len,const char * str,const struct qstr * name)672 static int ext4_d_compare(const struct dentry *dentry, unsigned int len,
673 			  const char *str, const struct qstr *name)
674 {
675 	struct qstr qstr = {.name = str, .len = len };
676 	struct inode *inode = dentry->d_parent->d_inode;
677 
678 	if (!IS_CASEFOLDED(inode) || !EXT4_SB(inode->i_sb)->s_encoding) {
679 		if (len != name->len)
680 			return -1;
681 		return memcmp(str, name->name, len);
682 	}
683 
684 	return ext4_ci_compare(inode, name, &qstr, false);
685 }
686 
ext4_d_hash(const struct dentry * dentry,struct qstr * str)687 static int ext4_d_hash(const struct dentry *dentry, struct qstr *str)
688 {
689 	const struct ext4_sb_info *sbi = EXT4_SB(dentry->d_sb);
690 	const struct unicode_map *um = sbi->s_encoding;
691 	unsigned char *norm;
692 	int len, ret = 0;
693 
694 	if (!IS_CASEFOLDED(dentry->d_inode) || !um)
695 		return 0;
696 
697 	norm = kmalloc(PATH_MAX, GFP_ATOMIC);
698 	if (!norm)
699 		return -ENOMEM;
700 
701 	len = utf8_casefold(um, str, norm, PATH_MAX);
702 	if (len < 0) {
703 		if (ext4_has_strict_mode(sbi))
704 			ret = -EINVAL;
705 		goto out;
706 	}
707 	str->hash = full_name_hash(dentry, norm, len);
708 out:
709 	kfree(norm);
710 	return ret;
711 }
712 
713 const struct dentry_operations ext4_dentry_ops = {
714 	.d_hash = ext4_d_hash,
715 	.d_compare = ext4_d_compare,
716 };
717 #endif
718