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_COMPAT_FEATURE(inode->i_sb,
44		     EXT4_FEATURE_COMPAT_DIR_INDEX) &&
45	    ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) ||
46	     ((inode->i_size >> sb->s_blocksize_bits) == 1) ||
47	     ext4_has_inline_data(inode)))
48		return 1;
49
50	return 0;
51}
52
53/*
54 * Return 0 if the directory entry is OK, and 1 if there is a problem
55 *
56 * Note: this is the opposite of what ext2 and ext3 historically returned...
57 *
58 * bh passed here can be an inode block or a dir data block, depending
59 * on the inode inline data flag.
60 */
61int __ext4_check_dir_entry(const char *function, unsigned int line,
62			   struct inode *dir, struct file *filp,
63			   struct ext4_dir_entry_2 *de,
64			   struct buffer_head *bh, char *buf, int size,
65			   unsigned int offset)
66{
67	const char *error_msg = NULL;
68	const int rlen = ext4_rec_len_from_disk(de->rec_len,
69						dir->i_sb->s_blocksize);
70
71	if (unlikely(rlen < EXT4_DIR_REC_LEN(1)))
72		error_msg = "rec_len is smaller than minimal";
73	else if (unlikely(rlen % 4 != 0))
74		error_msg = "rec_len % 4 != 0";
75	else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len)))
76		error_msg = "rec_len is too small for name_len";
77	else if (unlikely(((char *) de - buf) + rlen > size))
78		error_msg = "directory entry across range";
79	else if (unlikely(le32_to_cpu(de->inode) >
80			le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)))
81		error_msg = "inode out of bounds";
82	else
83		return 0;
84
85	if (filp)
86		ext4_error_file(filp, function, line, bh->b_blocknr,
87				"bad entry in directory: %s - offset=%u(%u), "
88				"inode=%u, rec_len=%d, name_len=%d",
89				error_msg, (unsigned) (offset % size),
90				offset, le32_to_cpu(de->inode),
91				rlen, de->name_len);
92	else
93		ext4_error_inode(dir, function, line, bh->b_blocknr,
94				"bad entry in directory: %s - offset=%u(%u), "
95				"inode=%u, rec_len=%d, name_len=%d",
96				error_msg, (unsigned) (offset % size),
97				offset, le32_to_cpu(de->inode),
98				rlen, de->name_len);
99
100	return 1;
101}
102
103static int ext4_readdir(struct file *file, struct dir_context *ctx)
104{
105	unsigned int offset;
106	int i;
107	struct ext4_dir_entry_2 *de;
108	int err;
109	struct inode *inode = file_inode(file);
110	struct super_block *sb = inode->i_sb;
111	struct buffer_head *bh = NULL;
112	int dir_has_error = 0;
113	struct ext4_fname_crypto_ctx *enc_ctx = NULL;
114	struct ext4_str fname_crypto_str = {.name = NULL, .len = 0};
115
116	if (is_dx_dir(inode)) {
117		err = ext4_dx_readdir(file, ctx);
118		if (err != ERR_BAD_DX_DIR) {
119			return err;
120		}
121		/*
122		 * We don't set the inode dirty flag since it's not
123		 * critical that it get flushed back to the disk.
124		 */
125		ext4_clear_inode_flag(file_inode(file),
126				      EXT4_INODE_INDEX);
127	}
128
129	if (ext4_has_inline_data(inode)) {
130		int has_inline_data = 1;
131		err = ext4_read_inline_dir(file, ctx,
132					   &has_inline_data);
133		if (has_inline_data)
134			return err;
135	}
136
137	enc_ctx = ext4_get_fname_crypto_ctx(inode, EXT4_NAME_LEN);
138	if (IS_ERR(enc_ctx))
139		return PTR_ERR(enc_ctx);
140	if (enc_ctx) {
141		err = ext4_fname_crypto_alloc_buffer(enc_ctx, EXT4_NAME_LEN,
142						     &fname_crypto_str);
143		if (err < 0) {
144			ext4_put_fname_crypto_ctx(&enc_ctx);
145			return err;
146		}
147	}
148
149	offset = ctx->pos & (sb->s_blocksize - 1);
150
151	while (ctx->pos < inode->i_size) {
152		struct ext4_map_blocks map;
153
154		map.m_lblk = ctx->pos >> EXT4_BLOCK_SIZE_BITS(sb);
155		map.m_len = 1;
156		err = ext4_map_blocks(NULL, inode, &map, 0);
157		if (err > 0) {
158			pgoff_t index = map.m_pblk >>
159					(PAGE_CACHE_SHIFT - inode->i_blkbits);
160			if (!ra_has_index(&file->f_ra, index))
161				page_cache_sync_readahead(
162					sb->s_bdev->bd_inode->i_mapping,
163					&file->f_ra, file,
164					index, 1);
165			file->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
166			bh = ext4_bread(NULL, inode, map.m_lblk, 0);
167			if (IS_ERR(bh))
168				return PTR_ERR(bh);
169		}
170
171		if (!bh) {
172			if (!dir_has_error) {
173				EXT4_ERROR_FILE(file, 0,
174						"directory contains a "
175						"hole at offset %llu",
176					   (unsigned long long) ctx->pos);
177				dir_has_error = 1;
178			}
179			/* corrupt size?  Maybe no more blocks to read */
180			if (ctx->pos > inode->i_blocks << 9)
181				break;
182			ctx->pos += sb->s_blocksize - offset;
183			continue;
184		}
185
186		/* Check the checksum */
187		if (!buffer_verified(bh) &&
188		    !ext4_dirent_csum_verify(inode,
189				(struct ext4_dir_entry *)bh->b_data)) {
190			EXT4_ERROR_FILE(file, 0, "directory fails checksum "
191					"at offset %llu",
192					(unsigned long long)ctx->pos);
193			ctx->pos += sb->s_blocksize - offset;
194			brelse(bh);
195			bh = NULL;
196			continue;
197		}
198		set_buffer_verified(bh);
199
200		/* If the dir block has changed since the last call to
201		 * readdir(2), then we might be pointing to an invalid
202		 * dirent right now.  Scan from the start of the block
203		 * to make sure. */
204		if (file->f_version != inode->i_version) {
205			for (i = 0; i < sb->s_blocksize && i < offset; ) {
206				de = (struct ext4_dir_entry_2 *)
207					(bh->b_data + i);
208				/* It's too expensive to do a full
209				 * dirent test each time round this
210				 * loop, but we do have to test at
211				 * least that it is non-zero.  A
212				 * failure will be detected in the
213				 * dirent test below. */
214				if (ext4_rec_len_from_disk(de->rec_len,
215					sb->s_blocksize) < EXT4_DIR_REC_LEN(1))
216					break;
217				i += ext4_rec_len_from_disk(de->rec_len,
218							    sb->s_blocksize);
219			}
220			offset = i;
221			ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1))
222				| offset;
223			file->f_version = inode->i_version;
224		}
225
226		while (ctx->pos < inode->i_size
227		       && offset < sb->s_blocksize) {
228			de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
229			if (ext4_check_dir_entry(inode, file, de, bh,
230						 bh->b_data, bh->b_size,
231						 offset)) {
232				/*
233				 * On error, skip to the next block
234				 */
235				ctx->pos = (ctx->pos |
236						(sb->s_blocksize - 1)) + 1;
237				break;
238			}
239			offset += ext4_rec_len_from_disk(de->rec_len,
240					sb->s_blocksize);
241			if (le32_to_cpu(de->inode)) {
242				if (enc_ctx == NULL) {
243					/* Directory is not encrypted */
244					if (!dir_emit(ctx, de->name,
245					    de->name_len,
246					    le32_to_cpu(de->inode),
247					    get_dtype(sb, de->file_type)))
248						goto done;
249				} else {
250					/* Directory is encrypted */
251					err = ext4_fname_disk_to_usr(enc_ctx,
252						NULL, de, &fname_crypto_str);
253					if (err < 0)
254						goto errout;
255					if (!dir_emit(ctx,
256					    fname_crypto_str.name, err,
257					    le32_to_cpu(de->inode),
258					    get_dtype(sb, de->file_type)))
259						goto done;
260				}
261			}
262			ctx->pos += ext4_rec_len_from_disk(de->rec_len,
263						sb->s_blocksize);
264		}
265		if ((ctx->pos < inode->i_size) && !dir_relax(inode))
266			goto done;
267		brelse(bh);
268		bh = NULL;
269		offset = 0;
270	}
271done:
272	err = 0;
273errout:
274#ifdef CONFIG_EXT4_FS_ENCRYPTION
275	ext4_put_fname_crypto_ctx(&enc_ctx);
276	ext4_fname_crypto_free_buffer(&fname_crypto_str);
277#endif
278	brelse(bh);
279	return err;
280}
281
282static inline int is_32bit_api(void)
283{
284#ifdef CONFIG_COMPAT
285	return is_compat_task();
286#else
287	return (BITS_PER_LONG == 32);
288#endif
289}
290
291/*
292 * These functions convert from the major/minor hash to an f_pos
293 * value for dx directories
294 *
295 * Upper layer (for example NFS) should specify FMODE_32BITHASH or
296 * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted
297 * directly on both 32-bit and 64-bit nodes, under such case, neither
298 * FMODE_32BITHASH nor FMODE_64BITHASH is specified.
299 */
300static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor)
301{
302	if ((filp->f_mode & FMODE_32BITHASH) ||
303	    (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
304		return major >> 1;
305	else
306		return ((__u64)(major >> 1) << 32) | (__u64)minor;
307}
308
309static inline __u32 pos2maj_hash(struct file *filp, loff_t pos)
310{
311	if ((filp->f_mode & FMODE_32BITHASH) ||
312	    (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
313		return (pos << 1) & 0xffffffff;
314	else
315		return ((pos >> 32) << 1) & 0xffffffff;
316}
317
318static inline __u32 pos2min_hash(struct file *filp, loff_t pos)
319{
320	if ((filp->f_mode & FMODE_32BITHASH) ||
321	    (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
322		return 0;
323	else
324		return pos & 0xffffffff;
325}
326
327/*
328 * Return 32- or 64-bit end-of-file for dx directories
329 */
330static inline loff_t ext4_get_htree_eof(struct file *filp)
331{
332	if ((filp->f_mode & FMODE_32BITHASH) ||
333	    (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
334		return EXT4_HTREE_EOF_32BIT;
335	else
336		return EXT4_HTREE_EOF_64BIT;
337}
338
339
340/*
341 * ext4_dir_llseek() calls generic_file_llseek_size to handle htree
342 * directories, where the "offset" is in terms of the filename hash
343 * value instead of the byte offset.
344 *
345 * Because we may return a 64-bit hash that is well beyond offset limits,
346 * we need to pass the max hash as the maximum allowable offset in
347 * the htree directory case.
348 *
349 * For non-htree, ext4_llseek already chooses the proper max offset.
350 */
351static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence)
352{
353	struct inode *inode = file->f_mapping->host;
354	int dx_dir = is_dx_dir(inode);
355	loff_t htree_max = ext4_get_htree_eof(file);
356
357	if (likely(dx_dir))
358		return generic_file_llseek_size(file, offset, whence,
359						    htree_max, htree_max);
360	else
361		return ext4_llseek(file, offset, whence);
362}
363
364/*
365 * This structure holds the nodes of the red-black tree used to store
366 * the directory entry in hash order.
367 */
368struct fname {
369	__u32		hash;
370	__u32		minor_hash;
371	struct rb_node	rb_hash;
372	struct fname	*next;
373	__u32		inode;
374	__u8		name_len;
375	__u8		file_type;
376	char		name[0];
377};
378
379/*
380 * This functoin implements a non-recursive way of freeing all of the
381 * nodes in the red-black tree.
382 */
383static void free_rb_tree_fname(struct rb_root *root)
384{
385	struct fname *fname, *next;
386
387	rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash)
388		while (fname) {
389			struct fname *old = fname;
390			fname = fname->next;
391			kfree(old);
392		}
393
394	*root = RB_ROOT;
395}
396
397
398static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp,
399							   loff_t pos)
400{
401	struct dir_private_info *p;
402
403	p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
404	if (!p)
405		return NULL;
406	p->curr_hash = pos2maj_hash(filp, pos);
407	p->curr_minor_hash = pos2min_hash(filp, pos);
408	return p;
409}
410
411void ext4_htree_free_dir_info(struct dir_private_info *p)
412{
413	free_rb_tree_fname(&p->root);
414	kfree(p);
415}
416
417/*
418 * Given a directory entry, enter it into the fname rb tree.
419 *
420 * When filename encryption is enabled, the dirent will hold the
421 * encrypted filename, while the htree will hold decrypted filename.
422 * The decrypted filename is passed in via ent_name.  parameter.
423 */
424int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
425			     __u32 minor_hash,
426			    struct ext4_dir_entry_2 *dirent,
427			    struct ext4_str *ent_name)
428{
429	struct rb_node **p, *parent = NULL;
430	struct fname *fname, *new_fn;
431	struct dir_private_info *info;
432	int len;
433
434	info = dir_file->private_data;
435	p = &info->root.rb_node;
436
437	/* Create and allocate the fname structure */
438	len = sizeof(struct fname) + ent_name->len + 1;
439	new_fn = kzalloc(len, GFP_KERNEL);
440	if (!new_fn)
441		return -ENOMEM;
442	new_fn->hash = hash;
443	new_fn->minor_hash = minor_hash;
444	new_fn->inode = le32_to_cpu(dirent->inode);
445	new_fn->name_len = ent_name->len;
446	new_fn->file_type = dirent->file_type;
447	memcpy(new_fn->name, ent_name->name, ent_name->len);
448	new_fn->name[ent_name->len] = 0;
449
450	while (*p) {
451		parent = *p;
452		fname = rb_entry(parent, struct fname, rb_hash);
453
454		/*
455		 * If the hash and minor hash match up, then we put
456		 * them on a linked list.  This rarely happens...
457		 */
458		if ((new_fn->hash == fname->hash) &&
459		    (new_fn->minor_hash == fname->minor_hash)) {
460			new_fn->next = fname->next;
461			fname->next = new_fn;
462			return 0;
463		}
464
465		if (new_fn->hash < fname->hash)
466			p = &(*p)->rb_left;
467		else if (new_fn->hash > fname->hash)
468			p = &(*p)->rb_right;
469		else if (new_fn->minor_hash < fname->minor_hash)
470			p = &(*p)->rb_left;
471		else /* if (new_fn->minor_hash > fname->minor_hash) */
472			p = &(*p)->rb_right;
473	}
474
475	rb_link_node(&new_fn->rb_hash, parent, p);
476	rb_insert_color(&new_fn->rb_hash, &info->root);
477	return 0;
478}
479
480
481
482/*
483 * This is a helper function for ext4_dx_readdir.  It calls filldir
484 * for all entres on the fname linked list.  (Normally there is only
485 * one entry on the linked list, unless there are 62 bit hash collisions.)
486 */
487static int call_filldir(struct file *file, struct dir_context *ctx,
488			struct fname *fname)
489{
490	struct dir_private_info *info = file->private_data;
491	struct inode *inode = file_inode(file);
492	struct super_block *sb = inode->i_sb;
493
494	if (!fname) {
495		ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: "
496			 "called with null fname?!?", __func__, __LINE__,
497			 inode->i_ino, current->comm);
498		return 0;
499	}
500	ctx->pos = hash2pos(file, fname->hash, fname->minor_hash);
501	while (fname) {
502		if (!dir_emit(ctx, fname->name,
503				fname->name_len,
504				fname->inode,
505				get_dtype(sb, fname->file_type))) {
506			info->extra_fname = fname;
507			return 1;
508		}
509		fname = fname->next;
510	}
511	return 0;
512}
513
514static int ext4_dx_readdir(struct file *file, struct dir_context *ctx)
515{
516	struct dir_private_info *info = file->private_data;
517	struct inode *inode = file_inode(file);
518	struct fname *fname;
519	int	ret;
520
521	if (!info) {
522		info = ext4_htree_create_dir_info(file, ctx->pos);
523		if (!info)
524			return -ENOMEM;
525		file->private_data = info;
526	}
527
528	if (ctx->pos == ext4_get_htree_eof(file))
529		return 0;	/* EOF */
530
531	/* Some one has messed with f_pos; reset the world */
532	if (info->last_pos != ctx->pos) {
533		free_rb_tree_fname(&info->root);
534		info->curr_node = NULL;
535		info->extra_fname = NULL;
536		info->curr_hash = pos2maj_hash(file, ctx->pos);
537		info->curr_minor_hash = pos2min_hash(file, ctx->pos);
538	}
539
540	/*
541	 * If there are any leftover names on the hash collision
542	 * chain, return them first.
543	 */
544	if (info->extra_fname) {
545		if (call_filldir(file, ctx, info->extra_fname))
546			goto finished;
547		info->extra_fname = NULL;
548		goto next_node;
549	} else if (!info->curr_node)
550		info->curr_node = rb_first(&info->root);
551
552	while (1) {
553		/*
554		 * Fill the rbtree if we have no more entries,
555		 * or the inode has changed since we last read in the
556		 * cached entries.
557		 */
558		if ((!info->curr_node) ||
559		    (file->f_version != inode->i_version)) {
560			info->curr_node = NULL;
561			free_rb_tree_fname(&info->root);
562			file->f_version = inode->i_version;
563			ret = ext4_htree_fill_tree(file, info->curr_hash,
564						   info->curr_minor_hash,
565						   &info->next_hash);
566			if (ret < 0)
567				return ret;
568			if (ret == 0) {
569				ctx->pos = ext4_get_htree_eof(file);
570				break;
571			}
572			info->curr_node = rb_first(&info->root);
573		}
574
575		fname = rb_entry(info->curr_node, struct fname, rb_hash);
576		info->curr_hash = fname->hash;
577		info->curr_minor_hash = fname->minor_hash;
578		if (call_filldir(file, ctx, fname))
579			break;
580	next_node:
581		info->curr_node = rb_next(info->curr_node);
582		if (info->curr_node) {
583			fname = rb_entry(info->curr_node, struct fname,
584					 rb_hash);
585			info->curr_hash = fname->hash;
586			info->curr_minor_hash = fname->minor_hash;
587		} else {
588			if (info->next_hash == ~0) {
589				ctx->pos = ext4_get_htree_eof(file);
590				break;
591			}
592			info->curr_hash = info->next_hash;
593			info->curr_minor_hash = 0;
594		}
595	}
596finished:
597	info->last_pos = ctx->pos;
598	return 0;
599}
600
601static int ext4_release_dir(struct inode *inode, struct file *filp)
602{
603	if (filp->private_data)
604		ext4_htree_free_dir_info(filp->private_data);
605
606	return 0;
607}
608
609int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf,
610		      int buf_size)
611{
612	struct ext4_dir_entry_2 *de;
613	int nlen, rlen;
614	unsigned int offset = 0;
615	char *top;
616
617	de = (struct ext4_dir_entry_2 *)buf;
618	top = buf + buf_size;
619	while ((char *) de < top) {
620		if (ext4_check_dir_entry(dir, NULL, de, bh,
621					 buf, buf_size, offset))
622			return -EIO;
623		nlen = EXT4_DIR_REC_LEN(de->name_len);
624		rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
625		de = (struct ext4_dir_entry_2 *)((char *)de + rlen);
626		offset += rlen;
627	}
628	if ((char *) de > top)
629		return -EIO;
630
631	return 0;
632}
633
634const struct file_operations ext4_dir_operations = {
635	.llseek		= ext4_dir_llseek,
636	.read		= generic_read_dir,
637	.iterate	= ext4_readdir,
638	.unlocked_ioctl = ext4_ioctl,
639#ifdef CONFIG_COMPAT
640	.compat_ioctl	= ext4_compat_ioctl,
641#endif
642	.fsync		= ext4_sync_file,
643	.release	= ext4_release_dir,
644};
645