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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/buffer_head.h>
26 #include <linux/slab.h>
27 #include "ext4.h"
28 #include "xattr.h"
29
30 static int ext4_dx_readdir(struct file *, struct dir_context *);
31
32 /**
33  * Check if the given dir-inode refers to an htree-indexed directory
34  * (or a directory which could potentially get converted to use htree
35  * indexing).
36  *
37  * Return 1 if it is a dx dir, 0 if not
38  */
39 static int is_dx_dir(struct inode *inode)
40 {
41         struct super_block *sb = inode->i_sb;
42
43         if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb,
44                      EXT4_FEATURE_COMPAT_DIR_INDEX) &&
45             ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) ||
46              ((inode->i_size >> sb->s_blocksize_bits) == 1) ||
47              ext4_has_inline_data(inode)))
48                 return 1;
49
50         return 0;
51 }
52
53 /*
54  * Return 0 if the directory entry is OK, and 1 if there is a problem
55  *
56  * Note: this is the opposite of what ext2 and ext3 historically returned...
57  *
58  * bh passed here can be an inode block or a dir data block, depending
59  * on the inode inline data flag.
60  */
61 int __ext4_check_dir_entry(const char *function, unsigned int line,
62                            struct inode *dir, struct file *filp,
63                            struct ext4_dir_entry_2 *de,
64                            struct buffer_head *bh, char *buf, int size,
65                            unsigned int offset)
66 {
67         const char *error_msg = NULL;
68         const int rlen = ext4_rec_len_from_disk(de->rec_len,
69                                                 dir->i_sb->s_blocksize);
70
71         if (unlikely(rlen < EXT4_DIR_REC_LEN(1)))
72                 error_msg = "rec_len is smaller than minimal";
73         else if (unlikely(rlen % 4 != 0))
74                 error_msg = "rec_len % 4 != 0";
75         else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len)))
76                 error_msg = "rec_len is too small for name_len";
77         else if (unlikely(((char *) de - buf) + rlen > size))
78                 error_msg = "directory entry across range";
79         else if (unlikely(le32_to_cpu(de->inode) >
80                         le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)))
81                 error_msg = "inode out of bounds";
82         else
83                 return 0;
84
85         if (filp)
86                 ext4_error_file(filp, function, line, bh->b_blocknr,
87                                 "bad entry in directory: %s - offset=%u(%u), "
88                                 "inode=%u, rec_len=%d, name_len=%d",
89                                 error_msg, (unsigned) (offset % size),
90                                 offset, le32_to_cpu(de->inode),
91                                 rlen, de->name_len);
92         else
93                 ext4_error_inode(dir, function, line, bh->b_blocknr,
94                                 "bad entry in directory: %s - offset=%u(%u), "
95                                 "inode=%u, rec_len=%d, name_len=%d",
96                                 error_msg, (unsigned) (offset % size),
97                                 offset, le32_to_cpu(de->inode),
98                                 rlen, de->name_len);
99
100         return 1;
101 }
102
103 static int ext4_readdir(struct file *file, struct dir_context *ctx)
104 {
105         unsigned int offset;
106         int i;
107         struct ext4_dir_entry_2 *de;
108         int err;
109         struct inode *inode = file_inode(file);
110         struct super_block *sb = inode->i_sb;
111         struct buffer_head *bh = NULL;
112         int dir_has_error = 0;
113         struct ext4_str fname_crypto_str = {.name = NULL, .len = 0};
114
115         if (is_dx_dir(inode)) {
116                 err = ext4_dx_readdir(file, ctx);
117                 if (err != ERR_BAD_DX_DIR) {
118                         return err;
119                 }
120                 /*
121                  * We don't set the inode dirty flag since it's not
122                  * critical that it get flushed back to the disk.
123                  */
124                 ext4_clear_inode_flag(file_inode(file),
125                                       EXT4_INODE_INDEX);
126         }
127
128         if (ext4_has_inline_data(inode)) {
129                 int has_inline_data = 1;
130                 err = ext4_read_inline_dir(file, ctx,
131                                            &has_inline_data);
132                 if (has_inline_data)
133                         return err;
134         }
135
136         if (ext4_encrypted_inode(inode)) {
137                 err = ext4_fname_crypto_alloc_buffer(inode, EXT4_NAME_LEN,
138                                                      &fname_crypto_str);
139                 if (err < 0)
140                         return err;
141         }
142
143         offset = ctx->pos & (sb->s_blocksize - 1);
144
145         while (ctx->pos < inode->i_size) {
146                 struct ext4_map_blocks map;
147
148                 map.m_lblk = ctx->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(&file->f_ra, index))
155                                 page_cache_sync_readahead(
156                                         sb->s_bdev->bd_inode->i_mapping,
157                                         &file->f_ra, file,
158                                         index, 1);
159                         file->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
160                         bh = ext4_bread(NULL, inode, map.m_lblk, 0);
161                         if (IS_ERR(bh))
162                                 return PTR_ERR(bh);
163                 }
164
165                 if (!bh) {
166                         if (!dir_has_error) {
167                                 EXT4_ERROR_FILE(file, 0,
168                                                 "directory contains a "
169                                                 "hole at offset %llu",
170                                            (unsigned long long) ctx->pos);
171                                 dir_has_error = 1;
172                         }
173                         /* corrupt size?  Maybe no more blocks to read */
174                         if (ctx->pos > inode->i_blocks << 9)
175                                 break;
176                         ctx->pos += sb->s_blocksize - offset;
177                         continue;
178                 }
179
180                 /* Check the checksum */
181                 if (!buffer_verified(bh) &&
182                     !ext4_dirent_csum_verify(inode,
183                                 (struct ext4_dir_entry *)bh->b_data)) {
184                         EXT4_ERROR_FILE(file, 0, "directory fails checksum "
185                                         "at offset %llu",
186                                         (unsigned long long)ctx->pos);
187                         ctx->pos += sb->s_blocksize - offset;
188                         brelse(bh);
189                         bh = NULL;
190                         continue;
191                 }
192                 set_buffer_verified(bh);
193
194                 /* If the dir block has changed since the last call to
195                  * readdir(2), then we might be pointing to an invalid
196                  * dirent right now.  Scan from the start of the block
197                  * to make sure. */
198                 if (file->f_version != inode->i_version) {
199                         for (i = 0; i < sb->s_blocksize && i < offset; ) {
200                                 de = (struct ext4_dir_entry_2 *)
201                                         (bh->b_data + i);
202                                 /* It's too expensive to do a full
203                                  * dirent test each time round this
204                                  * loop, but we do have to test at
205                                  * least that it is non-zero.  A
206                                  * failure will be detected in the
207                                  * dirent test below. */
208                                 if (ext4_rec_len_from_disk(de->rec_len,
209                                         sb->s_blocksize) < EXT4_DIR_REC_LEN(1))
210                                         break;
211                                 i += ext4_rec_len_from_disk(de->rec_len,
212                                                             sb->s_blocksize);
213                         }
214                         offset = i;
215                         ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1))
216                                 | offset;
217                         file->f_version = inode->i_version;
218                 }
219
220                 while (ctx->pos < inode->i_size
221                        && offset < sb->s_blocksize) {
222                         de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
223                         if (ext4_check_dir_entry(inode, file, de, bh,
224                                                  bh->b_data, bh->b_size,
225                                                  offset)) {
226                                 /*
227                                  * On error, skip to the next block
228                                  */
229                                 ctx->pos = (ctx->pos |
230                                                 (sb->s_blocksize - 1)) + 1;
231                                 break;
232                         }
233                         offset += ext4_rec_len_from_disk(de->rec_len,
234                                         sb->s_blocksize);
235                         if (le32_to_cpu(de->inode)) {
236                                 if (!ext4_encrypted_inode(inode)) {
237                                         if (!dir_emit(ctx, de->name,
238                                             de->name_len,
239                                             le32_to_cpu(de->inode),
240                                             get_dtype(sb, de->file_type)))
241                                                 goto done;
242                                 } else {
243                                         int save_len = fname_crypto_str.len;
244
245                                         /* Directory is encrypted */
246                                         err = ext4_fname_disk_to_usr(inode,
247                                                 NULL, de, &fname_crypto_str);
248                                         fname_crypto_str.len = save_len;
249                                         if (err < 0)
250                                                 goto errout;
251                                         if (!dir_emit(ctx,
252                                             fname_crypto_str.name, err,
253                                             le32_to_cpu(de->inode),
254                                             get_dtype(sb, de->file_type)))
255                                                 goto done;
256                                 }
257                         }
258                         ctx->pos += ext4_rec_len_from_disk(de->rec_len,
259                                                 sb->s_blocksize);
260                 }
261                 if ((ctx->pos < inode->i_size) && !dir_relax(inode))
262                         goto done;
263                 brelse(bh);
264                 bh = NULL;
265                 offset = 0;
266         }
267 done:
268         err = 0;
269 errout:
270 #ifdef CONFIG_EXT4_FS_ENCRYPTION
271         ext4_fname_crypto_free_buffer(&fname_crypto_str);
272 #endif
273         brelse(bh);
274         return err;
275 }
276
277 static inline int is_32bit_api(void)
278 {
279 #ifdef CONFIG_COMPAT
280         return is_compat_task();
281 #else
282         return (BITS_PER_LONG == 32);
283 #endif
284 }
285
286 /*
287  * These functions convert from the major/minor hash to an f_pos
288  * value for dx directories
289  *
290  * Upper layer (for example NFS) should specify FMODE_32BITHASH or
291  * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted
292  * directly on both 32-bit and 64-bit nodes, under such case, neither
293  * FMODE_32BITHASH nor FMODE_64BITHASH is specified.
294  */
295 static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor)
296 {
297         if ((filp->f_mode & FMODE_32BITHASH) ||
298             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
299                 return major >> 1;
300         else
301                 return ((__u64)(major >> 1) << 32) | (__u64)minor;
302 }
303
304 static inline __u32 pos2maj_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 (pos << 1) & 0xffffffff;
309         else
310                 return ((pos >> 32) << 1) & 0xffffffff;
311 }
312
313 static inline __u32 pos2min_hash(struct file *filp, loff_t pos)
314 {
315         if ((filp->f_mode & FMODE_32BITHASH) ||
316             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
317                 return 0;
318         else
319                 return pos & 0xffffffff;
320 }
321
322 /*
323  * Return 32- or 64-bit end-of-file for dx directories
324  */
325 static inline loff_t ext4_get_htree_eof(struct file *filp)
326 {
327         if ((filp->f_mode & FMODE_32BITHASH) ||
328             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
329                 return EXT4_HTREE_EOF_32BIT;
330         else
331                 return EXT4_HTREE_EOF_64BIT;
332 }
333
334
335 /*
336  * ext4_dir_llseek() calls generic_file_llseek_size to handle htree
337  * directories, where the "offset" is in terms of the filename hash
338  * value instead of the byte offset.
339  *
340  * Because we may return a 64-bit hash that is well beyond offset limits,
341  * we need to pass the max hash as the maximum allowable offset in
342  * the htree directory case.
343  *
344  * For non-htree, ext4_llseek already chooses the proper max offset.
345  */
346 static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence)
347 {
348         struct inode *inode = file->f_mapping->host;
349         int dx_dir = is_dx_dir(inode);
350         loff_t htree_max = ext4_get_htree_eof(file);
351
352         if (likely(dx_dir))
353                 return generic_file_llseek_size(file, offset, whence,
354                                                     htree_max, htree_max);
355         else
356                 return ext4_llseek(file, offset, whence);
357 }
358
359 /*
360  * This structure holds the nodes of the red-black tree used to store
361  * the directory entry in hash order.
362  */
363 struct fname {
364         __u32           hash;
365         __u32           minor_hash;
366         struct rb_node  rb_hash;
367         struct fname    *next;
368         __u32           inode;
369         __u8            name_len;
370         __u8            file_type;
371         char            name[0];
372 };
373
374 /*
375  * This functoin implements a non-recursive way of freeing all of the
376  * nodes in the red-black tree.
377  */
378 static void free_rb_tree_fname(struct rb_root *root)
379 {
380         struct fname *fname, *next;
381
382         rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash)
383                 while (fname) {
384                         struct fname *old = fname;
385                         fname = fname->next;
386                         kfree(old);
387                 }
388
389         *root = RB_ROOT;
390 }
391
392
393 static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp,
394                                                            loff_t pos)
395 {
396         struct dir_private_info *p;
397
398         p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
399         if (!p)
400                 return NULL;
401         p->curr_hash = pos2maj_hash(filp, pos);
402         p->curr_minor_hash = pos2min_hash(filp, pos);
403         return p;
404 }
405
406 void ext4_htree_free_dir_info(struct dir_private_info *p)
407 {
408         free_rb_tree_fname(&p->root);
409         kfree(p);
410 }
411
412 /*
413  * Given a directory entry, enter it into the fname rb tree.
414  *
415  * When filename encryption is enabled, the dirent will hold the
416  * encrypted filename, while the htree will hold decrypted filename.
417  * The decrypted filename is passed in via ent_name.  parameter.
418  */
419 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
420                              __u32 minor_hash,
421                             struct ext4_dir_entry_2 *dirent,
422                             struct ext4_str *ent_name)
423 {
424         struct rb_node **p, *parent = NULL;
425         struct fname *fname, *new_fn;
426         struct dir_private_info *info;
427         int len;
428
429         info = dir_file->private_data;
430         p = &info->root.rb_node;
431
432         /* Create and allocate the fname structure */
433         len = sizeof(struct fname) + ent_name->len + 1;
434         new_fn = kzalloc(len, GFP_KERNEL);
435         if (!new_fn)
436                 return -ENOMEM;
437         new_fn->hash = hash;
438         new_fn->minor_hash = minor_hash;
439         new_fn->inode = le32_to_cpu(dirent->inode);
440         new_fn->name_len = ent_name->len;
441         new_fn->file_type = dirent->file_type;
442         memcpy(new_fn->name, ent_name->name, ent_name->len);
443         new_fn->name[ent_name->len] = 0;
444
445         while (*p) {
446                 parent = *p;
447                 fname = rb_entry(parent, struct fname, rb_hash);
448
449                 /*
450                  * If the hash and minor hash match up, then we put
451                  * them on a linked list.  This rarely happens...
452                  */
453                 if ((new_fn->hash == fname->hash) &&
454                     (new_fn->minor_hash == fname->minor_hash)) {
455                         new_fn->next = fname->next;
456                         fname->next = new_fn;
457                         return 0;
458                 }
459
460                 if (new_fn->hash < fname->hash)
461                         p = &(*p)->rb_left;
462                 else if (new_fn->hash > fname->hash)
463                         p = &(*p)->rb_right;
464                 else if (new_fn->minor_hash < fname->minor_hash)
465                         p = &(*p)->rb_left;
466                 else /* if (new_fn->minor_hash > fname->minor_hash) */
467                         p = &(*p)->rb_right;
468         }
469
470         rb_link_node(&new_fn->rb_hash, parent, p);
471         rb_insert_color(&new_fn->rb_hash, &info->root);
472         return 0;
473 }
474
475
476
477 /*
478  * This is a helper function for ext4_dx_readdir.  It calls filldir
479  * for all entres on the fname linked list.  (Normally there is only
480  * one entry on the linked list, unless there are 62 bit hash collisions.)
481  */
482 static int call_filldir(struct file *file, struct dir_context *ctx,
483                         struct fname *fname)
484 {
485         struct dir_private_info *info = file->private_data;
486         struct inode *inode = file_inode(file);
487         struct super_block *sb = inode->i_sb;
488
489         if (!fname) {
490                 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: "
491                          "called with null fname?!?", __func__, __LINE__,
492                          inode->i_ino, current->comm);
493                 return 0;
494         }
495         ctx->pos = hash2pos(file, fname->hash, fname->minor_hash);
496         while (fname) {
497                 if (!dir_emit(ctx, fname->name,
498                                 fname->name_len,
499                                 fname->inode,
500                                 get_dtype(sb, fname->file_type))) {
501                         info->extra_fname = fname;
502                         return 1;
503                 }
504                 fname = fname->next;
505         }
506         return 0;
507 }
508
509 static int ext4_dx_readdir(struct file *file, struct dir_context *ctx)
510 {
511         struct dir_private_info *info = file->private_data;
512         struct inode *inode = file_inode(file);
513         struct fname *fname;
514         int     ret;
515
516         if (!info) {
517                 info = ext4_htree_create_dir_info(file, ctx->pos);
518                 if (!info)
519                         return -ENOMEM;
520                 file->private_data = info;
521         }
522
523         if (ctx->pos == ext4_get_htree_eof(file))
524                 return 0;       /* EOF */
525
526         /* Some one has messed with f_pos; reset the world */
527         if (info->last_pos != ctx->pos) {
528                 free_rb_tree_fname(&info->root);
529                 info->curr_node = NULL;
530                 info->extra_fname = NULL;
531                 info->curr_hash = pos2maj_hash(file, ctx->pos);
532                 info->curr_minor_hash = pos2min_hash(file, ctx->pos);
533         }
534
535         /*
536          * If there are any leftover names on the hash collision
537          * chain, return them first.
538          */
539         if (info->extra_fname) {
540                 if (call_filldir(file, ctx, info->extra_fname))
541                         goto finished;
542                 info->extra_fname = NULL;
543                 goto next_node;
544         } else if (!info->curr_node)
545                 info->curr_node = rb_first(&info->root);
546
547         while (1) {
548                 /*
549                  * Fill the rbtree if we have no more entries,
550                  * or the inode has changed since we last read in the
551                  * cached entries.
552                  */
553                 if ((!info->curr_node) ||
554                     (file->f_version != inode->i_version)) {
555                         info->curr_node = NULL;
556                         free_rb_tree_fname(&info->root);
557                         file->f_version = inode->i_version;
558                         ret = ext4_htree_fill_tree(file, info->curr_hash,
559                                                    info->curr_minor_hash,
560                                                    &info->next_hash);
561                         if (ret < 0)
562                                 return ret;
563                         if (ret == 0) {
564                                 ctx->pos = ext4_get_htree_eof(file);
565                                 break;
566                         }
567                         info->curr_node = rb_first(&info->root);
568                 }
569
570                 fname = rb_entry(info->curr_node, struct fname, rb_hash);
571                 info->curr_hash = fname->hash;
572                 info->curr_minor_hash = fname->minor_hash;
573                 if (call_filldir(file, ctx, fname))
574                         break;
575         next_node:
576                 info->curr_node = rb_next(info->curr_node);
577                 if (info->curr_node) {
578                         fname = rb_entry(info->curr_node, struct fname,
579                                          rb_hash);
580                         info->curr_hash = fname->hash;
581                         info->curr_minor_hash = fname->minor_hash;
582                 } else {
583                         if (info->next_hash == ~0) {
584                                 ctx->pos = ext4_get_htree_eof(file);
585                                 break;
586                         }
587                         info->curr_hash = info->next_hash;
588                         info->curr_minor_hash = 0;
589                 }
590         }
591 finished:
592         info->last_pos = ctx->pos;
593         return 0;
594 }
595
596 static int ext4_dir_open(struct inode * inode, struct file * filp)
597 {
598         if (ext4_encrypted_inode(inode))
599                 return ext4_get_encryption_info(inode) ? -EACCES : 0;
600         return 0;
601 }
602
603 static int ext4_release_dir(struct inode *inode, struct file *filp)
604 {
605         if (filp->private_data)
606                 ext4_htree_free_dir_info(filp->private_data);
607
608         return 0;
609 }
610
611 int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf,
612                       int buf_size)
613 {
614         struct ext4_dir_entry_2 *de;
615         int nlen, rlen;
616         unsigned int offset = 0;
617         char *top;
618
619         de = (struct ext4_dir_entry_2 *)buf;
620         top = buf + buf_size;
621         while ((char *) de < top) {
622                 if (ext4_check_dir_entry(dir, NULL, de, bh,
623                                          buf, buf_size, offset))
624                         return -EIO;
625                 nlen = EXT4_DIR_REC_LEN(de->name_len);
626                 rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
627                 de = (struct ext4_dir_entry_2 *)((char *)de + rlen);
628                 offset += rlen;
629         }
630         if ((char *) de > top)
631                 return -EIO;
632
633         return 0;
634 }
635
636 const struct file_operations ext4_dir_operations = {
637         .llseek         = ext4_dir_llseek,
638         .read           = generic_read_dir,
639         .iterate        = ext4_readdir,
640         .unlocked_ioctl = ext4_ioctl,
641 #ifdef CONFIG_COMPAT
642         .compat_ioctl   = ext4_compat_ioctl,
643 #endif
644         .fsync          = ext4_sync_file,
645         .open           = ext4_dir_open,
646         .release        = ext4_release_dir,
647 };