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1/*
2 * linux/fs/ext4/dir.c
3 *
4 * Copyright (C) 1992, 1993, 1994, 1995
5 * Remy Card (card@masi.ibp.fr)
6 * Laboratoire MASI - Institut Blaise Pascal
7 * Universite Pierre et Marie Curie (Paris VI)
8 *
9 * from
10 *
11 * linux/fs/minix/dir.c
12 *
13 * Copyright (C) 1991, 1992 Linus Torvalds
14 *
15 * ext4 directory handling functions
16 *
17 * Big-endian to little-endian byte-swapping/bitmaps by
18 * David S. Miller (davem@caip.rutgers.edu), 1995
19 *
20 * Hash Tree Directory indexing (c) 2001 Daniel Phillips
21 *
22 */
23
24#include <linux/fs.h>
25#include <linux/jbd2.h>
26#include <linux/buffer_head.h>
27#include <linux/slab.h>
28#include <linux/rbtree.h>
29#include "ext4.h"
30
31static unsigned char ext4_filetype_table[] = {
32 DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
33};
34
35static int ext4_readdir(struct file *, void *, filldir_t);
36static int ext4_dx_readdir(struct file *filp,
37 void *dirent, filldir_t filldir);
38static int ext4_release_dir(struct inode *inode,
39 struct file *filp);
40
41const struct file_operations ext4_dir_operations = {
42 .llseek = ext4_llseek,
43 .read = generic_read_dir,
44 .readdir = ext4_readdir, /* we take BKL. needed?*/
45 .unlocked_ioctl = ext4_ioctl,
46#ifdef CONFIG_COMPAT
47 .compat_ioctl = ext4_compat_ioctl,
48#endif
49 .fsync = ext4_sync_file,
50 .release = ext4_release_dir,
51};
52
53
54static unsigned char get_dtype(struct super_block *sb, int filetype)
55{
56 if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FILETYPE) ||
57 (filetype >= EXT4_FT_MAX))
58 return DT_UNKNOWN;
59
60 return (ext4_filetype_table[filetype]);
61}
62
63/*
64 * Return 0 if the directory entry is OK, and 1 if there is a problem
65 *
66 * Note: this is the opposite of what ext2 and ext3 historically returned...
67 */
68int __ext4_check_dir_entry(const char *function, unsigned int line,
69 struct inode *dir, struct file *filp,
70 struct ext4_dir_entry_2 *de,
71 struct buffer_head *bh,
72 unsigned int offset)
73{
74 const char *error_msg = NULL;
75 const int rlen = ext4_rec_len_from_disk(de->rec_len,
76 dir->i_sb->s_blocksize);
77
78 if (unlikely(rlen < EXT4_DIR_REC_LEN(1)))
79 error_msg = "rec_len is smaller than minimal";
80 else if (unlikely(rlen % 4 != 0))
81 error_msg = "rec_len % 4 != 0";
82 else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len)))
83 error_msg = "rec_len is too small for name_len";
84 else if (unlikely(((char *) de - bh->b_data) + rlen >
85 dir->i_sb->s_blocksize))
86 error_msg = "directory entry across blocks";
87 else if (unlikely(le32_to_cpu(de->inode) >
88 le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)))
89 error_msg = "inode out of bounds";
90 else
91 return 0;
92
93 if (filp)
94 ext4_error_file(filp, function, line, bh ? bh->b_blocknr : 0,
95 "bad entry in directory: %s - offset=%u(%u), "
96 "inode=%u, rec_len=%d, name_len=%d",
97 error_msg, (unsigned) (offset%bh->b_size),
98 offset, le32_to_cpu(de->inode),
99 rlen, de->name_len);
100 else
101 ext4_error_inode(dir, function, line, bh ? bh->b_blocknr : 0,
102 "bad entry in directory: %s - offset=%u(%u), "
103 "inode=%u, rec_len=%d, name_len=%d",
104 error_msg, (unsigned) (offset%bh->b_size),
105 offset, le32_to_cpu(de->inode),
106 rlen, de->name_len);
107
108 return 1;
109}
110
111static int ext4_readdir(struct file *filp,
112 void *dirent, filldir_t filldir)
113{
114 int error = 0;
115 unsigned int offset;
116 int i, stored;
117 struct ext4_dir_entry_2 *de;
118 struct super_block *sb;
119 int err;
120 struct inode *inode = filp->f_path.dentry->d_inode;
121 int ret = 0;
122 int dir_has_error = 0;
123
124 sb = inode->i_sb;
125
126 if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb,
127 EXT4_FEATURE_COMPAT_DIR_INDEX) &&
128 ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) ||
129 ((inode->i_size >> sb->s_blocksize_bits) == 1))) {
130 err = ext4_dx_readdir(filp, dirent, filldir);
131 if (err != ERR_BAD_DX_DIR) {
132 ret = err;
133 goto out;
134 }
135 /*
136 * We don't set the inode dirty flag since it's not
137 * critical that it get flushed back to the disk.
138 */
139 ext4_clear_inode_flag(filp->f_path.dentry->d_inode,
140 EXT4_INODE_INDEX);
141 }
142 stored = 0;
143 offset = filp->f_pos & (sb->s_blocksize - 1);
144
145 while (!error && !stored && filp->f_pos < inode->i_size) {
146 struct ext4_map_blocks map;
147 struct buffer_head *bh = NULL;
148
149 map.m_lblk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb);
150 map.m_len = 1;
151 err = ext4_map_blocks(NULL, inode, &map, 0);
152 if (err > 0) {
153 pgoff_t index = map.m_pblk >>
154 (PAGE_CACHE_SHIFT - inode->i_blkbits);
155 if (!ra_has_index(&filp->f_ra, index))
156 page_cache_sync_readahead(
157 sb->s_bdev->bd_inode->i_mapping,
158 &filp->f_ra, filp,
159 index, 1);
160 filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
161 bh = ext4_bread(NULL, inode, map.m_lblk, 0, &err);
162 }
163
164 /*
165 * We ignore I/O errors on directories so users have a chance
166 * of recovering data when there's a bad sector
167 */
168 if (!bh) {
169 if (!dir_has_error) {
170 EXT4_ERROR_FILE(filp, 0,
171 "directory contains a "
172 "hole at offset %llu",
173 (unsigned long long) filp->f_pos);
174 dir_has_error = 1;
175 }
176 /* corrupt size? Maybe no more blocks to read */
177 if (filp->f_pos > inode->i_blocks << 9)
178 break;
179 filp->f_pos += sb->s_blocksize - offset;
180 continue;
181 }
182
183revalidate:
184 /* If the dir block has changed since the last call to
185 * readdir(2), then we might be pointing to an invalid
186 * dirent right now. Scan from the start of the block
187 * to make sure. */
188 if (filp->f_version != inode->i_version) {
189 for (i = 0; i < sb->s_blocksize && i < offset; ) {
190 de = (struct ext4_dir_entry_2 *)
191 (bh->b_data + i);
192 /* It's too expensive to do a full
193 * dirent test each time round this
194 * loop, but we do have to test at
195 * least that it is non-zero. A
196 * failure will be detected in the
197 * dirent test below. */
198 if (ext4_rec_len_from_disk(de->rec_len,
199 sb->s_blocksize) < EXT4_DIR_REC_LEN(1))
200 break;
201 i += ext4_rec_len_from_disk(de->rec_len,
202 sb->s_blocksize);
203 }
204 offset = i;
205 filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
206 | offset;
207 filp->f_version = inode->i_version;
208 }
209
210 while (!error && filp->f_pos < inode->i_size
211 && offset < sb->s_blocksize) {
212 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
213 if (ext4_check_dir_entry(inode, filp, de,
214 bh, offset)) {
215 /*
216 * On error, skip the f_pos to the next block
217 */
218 filp->f_pos = (filp->f_pos |
219 (sb->s_blocksize - 1)) + 1;
220 brelse(bh);
221 ret = stored;
222 goto out;
223 }
224 offset += ext4_rec_len_from_disk(de->rec_len,
225 sb->s_blocksize);
226 if (le32_to_cpu(de->inode)) {
227 /* We might block in the next section
228 * if the data destination is
229 * currently swapped out. So, use a
230 * version stamp to detect whether or
231 * not the directory has been modified
232 * during the copy operation.
233 */
234 u64 version = filp->f_version;
235
236 error = filldir(dirent, de->name,
237 de->name_len,
238 filp->f_pos,
239 le32_to_cpu(de->inode),
240 get_dtype(sb, de->file_type));
241 if (error)
242 break;
243 if (version != filp->f_version)
244 goto revalidate;
245 stored++;
246 }
247 filp->f_pos += ext4_rec_len_from_disk(de->rec_len,
248 sb->s_blocksize);
249 }
250 offset = 0;
251 brelse(bh);
252 }
253out:
254 return ret;
255}
256
257/*
258 * These functions convert from the major/minor hash to an f_pos
259 * value.
260 *
261 * Currently we only use major hash numer. This is unfortunate, but
262 * on 32-bit machines, the same VFS interface is used for lseek and
263 * llseek, so if we use the 64 bit offset, then the 32-bit versions of
264 * lseek/telldir/seekdir will blow out spectacularly, and from within
265 * the ext2 low-level routine, we don't know if we're being called by
266 * a 64-bit version of the system call or the 32-bit version of the
267 * system call. Worse yet, NFSv2 only allows for a 32-bit readdir
268 * cookie. Sigh.
269 */
270#define hash2pos(major, minor) (major >> 1)
271#define pos2maj_hash(pos) ((pos << 1) & 0xffffffff)
272#define pos2min_hash(pos) (0)
273
274/*
275 * This structure holds the nodes of the red-black tree used to store
276 * the directory entry in hash order.
277 */
278struct fname {
279 __u32 hash;
280 __u32 minor_hash;
281 struct rb_node rb_hash;
282 struct fname *next;
283 __u32 inode;
284 __u8 name_len;
285 __u8 file_type;
286 char name[0];
287};
288
289/*
290 * This functoin implements a non-recursive way of freeing all of the
291 * nodes in the red-black tree.
292 */
293static void free_rb_tree_fname(struct rb_root *root)
294{
295 struct rb_node *n = root->rb_node;
296 struct rb_node *parent;
297 struct fname *fname;
298
299 while (n) {
300 /* Do the node's children first */
301 if (n->rb_left) {
302 n = n->rb_left;
303 continue;
304 }
305 if (n->rb_right) {
306 n = n->rb_right;
307 continue;
308 }
309 /*
310 * The node has no children; free it, and then zero
311 * out parent's link to it. Finally go to the
312 * beginning of the loop and try to free the parent
313 * node.
314 */
315 parent = rb_parent(n);
316 fname = rb_entry(n, struct fname, rb_hash);
317 while (fname) {
318 struct fname *old = fname;
319 fname = fname->next;
320 kfree(old);
321 }
322 if (!parent)
323 *root = RB_ROOT;
324 else if (parent->rb_left == n)
325 parent->rb_left = NULL;
326 else if (parent->rb_right == n)
327 parent->rb_right = NULL;
328 n = parent;
329 }
330}
331
332
333static struct dir_private_info *ext4_htree_create_dir_info(loff_t pos)
334{
335 struct dir_private_info *p;
336
337 p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
338 if (!p)
339 return NULL;
340 p->curr_hash = pos2maj_hash(pos);
341 p->curr_minor_hash = pos2min_hash(pos);
342 return p;
343}
344
345void ext4_htree_free_dir_info(struct dir_private_info *p)
346{
347 free_rb_tree_fname(&p->root);
348 kfree(p);
349}
350
351/*
352 * Given a directory entry, enter it into the fname rb tree.
353 */
354int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
355 __u32 minor_hash,
356 struct ext4_dir_entry_2 *dirent)
357{
358 struct rb_node **p, *parent = NULL;
359 struct fname *fname, *new_fn;
360 struct dir_private_info *info;
361 int len;
362
363 info = dir_file->private_data;
364 p = &info->root.rb_node;
365
366 /* Create and allocate the fname structure */
367 len = sizeof(struct fname) + dirent->name_len + 1;
368 new_fn = kzalloc(len, GFP_KERNEL);
369 if (!new_fn)
370 return -ENOMEM;
371 new_fn->hash = hash;
372 new_fn->minor_hash = minor_hash;
373 new_fn->inode = le32_to_cpu(dirent->inode);
374 new_fn->name_len = dirent->name_len;
375 new_fn->file_type = dirent->file_type;
376 memcpy(new_fn->name, dirent->name, dirent->name_len);
377 new_fn->name[dirent->name_len] = 0;
378
379 while (*p) {
380 parent = *p;
381 fname = rb_entry(parent, struct fname, rb_hash);
382
383 /*
384 * If the hash and minor hash match up, then we put
385 * them on a linked list. This rarely happens...
386 */
387 if ((new_fn->hash == fname->hash) &&
388 (new_fn->minor_hash == fname->minor_hash)) {
389 new_fn->next = fname->next;
390 fname->next = new_fn;
391 return 0;
392 }
393
394 if (new_fn->hash < fname->hash)
395 p = &(*p)->rb_left;
396 else if (new_fn->hash > fname->hash)
397 p = &(*p)->rb_right;
398 else if (new_fn->minor_hash < fname->minor_hash)
399 p = &(*p)->rb_left;
400 else /* if (new_fn->minor_hash > fname->minor_hash) */
401 p = &(*p)->rb_right;
402 }
403
404 rb_link_node(&new_fn->rb_hash, parent, p);
405 rb_insert_color(&new_fn->rb_hash, &info->root);
406 return 0;
407}
408
409
410
411/*
412 * This is a helper function for ext4_dx_readdir. It calls filldir
413 * for all entres on the fname linked list. (Normally there is only
414 * one entry on the linked list, unless there are 62 bit hash collisions.)
415 */
416static int call_filldir(struct file *filp, void *dirent,
417 filldir_t filldir, struct fname *fname)
418{
419 struct dir_private_info *info = filp->private_data;
420 loff_t curr_pos;
421 struct inode *inode = filp->f_path.dentry->d_inode;
422 struct super_block *sb;
423 int error;
424
425 sb = inode->i_sb;
426
427 if (!fname) {
428 printk(KERN_ERR "EXT4-fs: call_filldir: called with "
429 "null fname?!?\n");
430 return 0;
431 }
432 curr_pos = hash2pos(fname->hash, fname->minor_hash);
433 while (fname) {
434 error = filldir(dirent, fname->name,
435 fname->name_len, curr_pos,
436 fname->inode,
437 get_dtype(sb, fname->file_type));
438 if (error) {
439 filp->f_pos = curr_pos;
440 info->extra_fname = fname;
441 return error;
442 }
443 fname = fname->next;
444 }
445 return 0;
446}
447
448static int ext4_dx_readdir(struct file *filp,
449 void *dirent, filldir_t filldir)
450{
451 struct dir_private_info *info = filp->private_data;
452 struct inode *inode = filp->f_path.dentry->d_inode;
453 struct fname *fname;
454 int ret;
455
456 if (!info) {
457 info = ext4_htree_create_dir_info(filp->f_pos);
458 if (!info)
459 return -ENOMEM;
460 filp->private_data = info;
461 }
462
463 if (filp->f_pos == EXT4_HTREE_EOF)
464 return 0; /* EOF */
465
466 /* Some one has messed with f_pos; reset the world */
467 if (info->last_pos != filp->f_pos) {
468 free_rb_tree_fname(&info->root);
469 info->curr_node = NULL;
470 info->extra_fname = NULL;
471 info->curr_hash = pos2maj_hash(filp->f_pos);
472 info->curr_minor_hash = pos2min_hash(filp->f_pos);
473 }
474
475 /*
476 * If there are any leftover names on the hash collision
477 * chain, return them first.
478 */
479 if (info->extra_fname) {
480 if (call_filldir(filp, dirent, filldir, info->extra_fname))
481 goto finished;
482 info->extra_fname = NULL;
483 goto next_node;
484 } else if (!info->curr_node)
485 info->curr_node = rb_first(&info->root);
486
487 while (1) {
488 /*
489 * Fill the rbtree if we have no more entries,
490 * or the inode has changed since we last read in the
491 * cached entries.
492 */
493 if ((!info->curr_node) ||
494 (filp->f_version != inode->i_version)) {
495 info->curr_node = NULL;
496 free_rb_tree_fname(&info->root);
497 filp->f_version = inode->i_version;
498 ret = ext4_htree_fill_tree(filp, info->curr_hash,
499 info->curr_minor_hash,
500 &info->next_hash);
501 if (ret < 0)
502 return ret;
503 if (ret == 0) {
504 filp->f_pos = EXT4_HTREE_EOF;
505 break;
506 }
507 info->curr_node = rb_first(&info->root);
508 }
509
510 fname = rb_entry(info->curr_node, struct fname, rb_hash);
511 info->curr_hash = fname->hash;
512 info->curr_minor_hash = fname->minor_hash;
513 if (call_filldir(filp, dirent, filldir, fname))
514 break;
515 next_node:
516 info->curr_node = rb_next(info->curr_node);
517 if (info->curr_node) {
518 fname = rb_entry(info->curr_node, struct fname,
519 rb_hash);
520 info->curr_hash = fname->hash;
521 info->curr_minor_hash = fname->minor_hash;
522 } else {
523 if (info->next_hash == ~0) {
524 filp->f_pos = EXT4_HTREE_EOF;
525 break;
526 }
527 info->curr_hash = info->next_hash;
528 info->curr_minor_hash = 0;
529 }
530 }
531finished:
532 info->last_pos = filp->f_pos;
533 return 0;
534}
535
536static int ext4_release_dir(struct inode *inode, struct file *filp)
537{
538 if (filp->private_data)
539 ext4_htree_free_dir_info(filp->private_data);
540
541 return 0;
542}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/fs/ext4/dir.c
4 *
5 * Copyright (C) 1992, 1993, 1994, 1995
6 * Remy Card (card@masi.ibp.fr)
7 * Laboratoire MASI - Institut Blaise Pascal
8 * Universite Pierre et Marie Curie (Paris VI)
9 *
10 * from
11 *
12 * linux/fs/minix/dir.c
13 *
14 * Copyright (C) 1991, 1992 Linus Torvalds
15 *
16 * ext4 directory handling functions
17 *
18 * Big-endian to little-endian byte-swapping/bitmaps by
19 * David S. Miller (davem@caip.rutgers.edu), 1995
20 *
21 * Hash Tree Directory indexing (c) 2001 Daniel Phillips
22 *
23 */
24
25#include <linux/fs.h>
26#include <linux/buffer_head.h>
27#include <linux/slab.h>
28#include <linux/iversion.h>
29#include <linux/unicode.h>
30#include "ext4.h"
31#include "xattr.h"
32
33static int ext4_dx_readdir(struct file *, struct dir_context *);
34
35/**
36 * is_dx_dir() - check if a directory is using htree indexing
37 * @inode: directory inode
38 *
39 * Check if the given dir-inode refers to an htree-indexed directory
40 * (or a directory which could potentially get converted to use htree
41 * indexing).
42 *
43 * Return 1 if it is a dx dir, 0 if not
44 */
45static int is_dx_dir(struct inode *inode)
46{
47 struct super_block *sb = inode->i_sb;
48
49 if (ext4_has_feature_dir_index(inode->i_sb) &&
50 ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) ||
51 ((inode->i_size >> sb->s_blocksize_bits) == 1) ||
52 ext4_has_inline_data(inode)))
53 return 1;
54
55 return 0;
56}
57
58static bool is_fake_dir_entry(struct ext4_dir_entry_2 *de)
59{
60 /* Check if . or .. , or skip if namelen is 0 */
61 if ((de->name_len > 0) && (de->name_len <= 2) && (de->name[0] == '.') &&
62 (de->name[1] == '.' || de->name[1] == '\0'))
63 return true;
64 /* Check if this is a csum entry */
65 if (de->file_type == EXT4_FT_DIR_CSUM)
66 return true;
67 return false;
68}
69
70/*
71 * Return 0 if the directory entry is OK, and 1 if there is a problem
72 *
73 * Note: this is the opposite of what ext2 and ext3 historically returned...
74 *
75 * bh passed here can be an inode block or a dir data block, depending
76 * on the inode inline data flag.
77 */
78int __ext4_check_dir_entry(const char *function, unsigned int line,
79 struct inode *dir, struct file *filp,
80 struct ext4_dir_entry_2 *de,
81 struct buffer_head *bh, char *buf, int size,
82 unsigned int offset)
83{
84 const char *error_msg = NULL;
85 const int rlen = ext4_rec_len_from_disk(de->rec_len,
86 dir->i_sb->s_blocksize);
87 const int next_offset = ((char *) de - buf) + rlen;
88 bool fake = is_fake_dir_entry(de);
89 bool has_csum = ext4_has_metadata_csum(dir->i_sb);
90
91 if (unlikely(rlen < ext4_dir_rec_len(1, fake ? NULL : dir)))
92 error_msg = "rec_len is smaller than minimal";
93 else if (unlikely(rlen % 4 != 0))
94 error_msg = "rec_len % 4 != 0";
95 else if (unlikely(rlen < ext4_dir_rec_len(de->name_len,
96 fake ? NULL : dir)))
97 error_msg = "rec_len is too small for name_len";
98 else if (unlikely(next_offset > size))
99 error_msg = "directory entry overrun";
100 else if (unlikely(next_offset > size - ext4_dir_rec_len(1,
101 has_csum ? NULL : dir) &&
102 next_offset != size))
103 error_msg = "directory entry too close to block end";
104 else if (unlikely(le32_to_cpu(de->inode) >
105 le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)))
106 error_msg = "inode out of bounds";
107 else
108 return 0;
109
110 if (filp)
111 ext4_error_file(filp, function, line, bh->b_blocknr,
112 "bad entry in directory: %s - offset=%u, "
113 "inode=%u, rec_len=%d, size=%d fake=%d",
114 error_msg, offset, le32_to_cpu(de->inode),
115 rlen, size, fake);
116 else
117 ext4_error_inode(dir, function, line, bh->b_blocknr,
118 "bad entry in directory: %s - offset=%u, "
119 "inode=%u, rec_len=%d, size=%d fake=%d",
120 error_msg, offset, le32_to_cpu(de->inode),
121 rlen, size, fake);
122
123 return 1;
124}
125
126static int ext4_readdir(struct file *file, struct dir_context *ctx)
127{
128 unsigned int offset;
129 int i;
130 struct ext4_dir_entry_2 *de;
131 int err;
132 struct inode *inode = file_inode(file);
133 struct super_block *sb = inode->i_sb;
134 struct buffer_head *bh = NULL;
135 struct fscrypt_str fstr = FSTR_INIT(NULL, 0);
136
137 err = fscrypt_prepare_readdir(inode);
138 if (err)
139 return err;
140
141 if (is_dx_dir(inode)) {
142 err = ext4_dx_readdir(file, ctx);
143 if (err != ERR_BAD_DX_DIR)
144 return err;
145
146 /* Can we just clear INDEX flag to ignore htree information? */
147 if (!ext4_has_metadata_csum(sb)) {
148 /*
149 * We don't set the inode dirty flag since it's not
150 * critical that it gets flushed back to the disk.
151 */
152 ext4_clear_inode_flag(inode, EXT4_INODE_INDEX);
153 }
154 }
155
156 if (ext4_has_inline_data(inode)) {
157 int has_inline_data = 1;
158 err = ext4_read_inline_dir(file, ctx,
159 &has_inline_data);
160 if (has_inline_data)
161 return err;
162 }
163
164 if (IS_ENCRYPTED(inode)) {
165 err = fscrypt_fname_alloc_buffer(EXT4_NAME_LEN, &fstr);
166 if (err < 0)
167 return err;
168 }
169
170 while (ctx->pos < inode->i_size) {
171 struct ext4_map_blocks map;
172
173 if (fatal_signal_pending(current)) {
174 err = -ERESTARTSYS;
175 goto errout;
176 }
177 cond_resched();
178 offset = ctx->pos & (sb->s_blocksize - 1);
179 map.m_lblk = ctx->pos >> EXT4_BLOCK_SIZE_BITS(sb);
180 map.m_len = 1;
181 err = ext4_map_blocks(NULL, inode, &map, 0);
182 if (err == 0) {
183 /* m_len should never be zero but let's avoid
184 * an infinite loop if it somehow is */
185 if (map.m_len == 0)
186 map.m_len = 1;
187 ctx->pos += map.m_len * sb->s_blocksize;
188 continue;
189 }
190 if (err > 0) {
191 pgoff_t index = map.m_pblk >>
192 (PAGE_SHIFT - inode->i_blkbits);
193 if (!ra_has_index(&file->f_ra, index))
194 page_cache_sync_readahead(
195 sb->s_bdev->bd_inode->i_mapping,
196 &file->f_ra, file,
197 index, 1);
198 file->f_ra.prev_pos = (loff_t)index << PAGE_SHIFT;
199 bh = ext4_bread(NULL, inode, map.m_lblk, 0);
200 if (IS_ERR(bh)) {
201 err = PTR_ERR(bh);
202 bh = NULL;
203 goto errout;
204 }
205 }
206
207 if (!bh) {
208 /* corrupt size? Maybe no more blocks to read */
209 if (ctx->pos > inode->i_blocks << 9)
210 break;
211 ctx->pos += sb->s_blocksize - offset;
212 continue;
213 }
214
215 /* Check the checksum */
216 if (!buffer_verified(bh) &&
217 !ext4_dirblock_csum_verify(inode, bh)) {
218 EXT4_ERROR_FILE(file, 0, "directory fails checksum "
219 "at offset %llu",
220 (unsigned long long)ctx->pos);
221 ctx->pos += sb->s_blocksize - offset;
222 brelse(bh);
223 bh = NULL;
224 continue;
225 }
226 set_buffer_verified(bh);
227
228 /* If the dir block has changed since the last call to
229 * readdir(2), then we might be pointing to an invalid
230 * dirent right now. Scan from the start of the block
231 * to make sure. */
232 if (!inode_eq_iversion(inode, file->f_version)) {
233 for (i = 0; i < sb->s_blocksize && i < offset; ) {
234 de = (struct ext4_dir_entry_2 *)
235 (bh->b_data + i);
236 /* It's too expensive to do a full
237 * dirent test each time round this
238 * loop, but we do have to test at
239 * least that it is non-zero. A
240 * failure will be detected in the
241 * dirent test below. */
242 if (ext4_rec_len_from_disk(de->rec_len,
243 sb->s_blocksize) < ext4_dir_rec_len(1,
244 inode))
245 break;
246 i += ext4_rec_len_from_disk(de->rec_len,
247 sb->s_blocksize);
248 }
249 offset = i;
250 ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1))
251 | offset;
252 file->f_version = inode_query_iversion(inode);
253 }
254
255 while (ctx->pos < inode->i_size
256 && offset < sb->s_blocksize) {
257 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
258 if (ext4_check_dir_entry(inode, file, de, bh,
259 bh->b_data, bh->b_size,
260 offset)) {
261 /*
262 * On error, skip to the next block
263 */
264 ctx->pos = (ctx->pos |
265 (sb->s_blocksize - 1)) + 1;
266 break;
267 }
268 offset += ext4_rec_len_from_disk(de->rec_len,
269 sb->s_blocksize);
270 if (le32_to_cpu(de->inode)) {
271 if (!IS_ENCRYPTED(inode)) {
272 if (!dir_emit(ctx, de->name,
273 de->name_len,
274 le32_to_cpu(de->inode),
275 get_dtype(sb, de->file_type)))
276 goto done;
277 } else {
278 int save_len = fstr.len;
279 struct fscrypt_str de_name =
280 FSTR_INIT(de->name,
281 de->name_len);
282
283 /* Directory is encrypted */
284 err = fscrypt_fname_disk_to_usr(inode,
285 EXT4_DIRENT_HASH(de),
286 EXT4_DIRENT_MINOR_HASH(de),
287 &de_name, &fstr);
288 de_name = fstr;
289 fstr.len = save_len;
290 if (err)
291 goto errout;
292 if (!dir_emit(ctx,
293 de_name.name, de_name.len,
294 le32_to_cpu(de->inode),
295 get_dtype(sb, de->file_type)))
296 goto done;
297 }
298 }
299 ctx->pos += ext4_rec_len_from_disk(de->rec_len,
300 sb->s_blocksize);
301 }
302 if ((ctx->pos < inode->i_size) && !dir_relax_shared(inode))
303 goto done;
304 brelse(bh);
305 bh = NULL;
306 offset = 0;
307 }
308done:
309 err = 0;
310errout:
311 fscrypt_fname_free_buffer(&fstr);
312 brelse(bh);
313 return err;
314}
315
316static inline int is_32bit_api(void)
317{
318#ifdef CONFIG_COMPAT
319 return in_compat_syscall();
320#else
321 return (BITS_PER_LONG == 32);
322#endif
323}
324
325/*
326 * These functions convert from the major/minor hash to an f_pos
327 * value for dx directories
328 *
329 * Upper layer (for example NFS) should specify FMODE_32BITHASH or
330 * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted
331 * directly on both 32-bit and 64-bit nodes, under such case, neither
332 * FMODE_32BITHASH nor FMODE_64BITHASH is specified.
333 */
334static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor)
335{
336 if ((filp->f_mode & FMODE_32BITHASH) ||
337 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
338 return major >> 1;
339 else
340 return ((__u64)(major >> 1) << 32) | (__u64)minor;
341}
342
343static inline __u32 pos2maj_hash(struct file *filp, loff_t pos)
344{
345 if ((filp->f_mode & FMODE_32BITHASH) ||
346 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
347 return (pos << 1) & 0xffffffff;
348 else
349 return ((pos >> 32) << 1) & 0xffffffff;
350}
351
352static inline __u32 pos2min_hash(struct file *filp, loff_t pos)
353{
354 if ((filp->f_mode & FMODE_32BITHASH) ||
355 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
356 return 0;
357 else
358 return pos & 0xffffffff;
359}
360
361/*
362 * Return 32- or 64-bit end-of-file for dx directories
363 */
364static inline loff_t ext4_get_htree_eof(struct file *filp)
365{
366 if ((filp->f_mode & FMODE_32BITHASH) ||
367 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
368 return EXT4_HTREE_EOF_32BIT;
369 else
370 return EXT4_HTREE_EOF_64BIT;
371}
372
373
374/*
375 * ext4_dir_llseek() calls generic_file_llseek_size to handle htree
376 * directories, where the "offset" is in terms of the filename hash
377 * value instead of the byte offset.
378 *
379 * Because we may return a 64-bit hash that is well beyond offset limits,
380 * we need to pass the max hash as the maximum allowable offset in
381 * the htree directory case.
382 *
383 * For non-htree, ext4_llseek already chooses the proper max offset.
384 */
385static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence)
386{
387 struct inode *inode = file->f_mapping->host;
388 int dx_dir = is_dx_dir(inode);
389 loff_t ret, htree_max = ext4_get_htree_eof(file);
390
391 if (likely(dx_dir))
392 ret = generic_file_llseek_size(file, offset, whence,
393 htree_max, htree_max);
394 else
395 ret = ext4_llseek(file, offset, whence);
396 file->f_version = inode_peek_iversion(inode) - 1;
397 return ret;
398}
399
400/*
401 * This structure holds the nodes of the red-black tree used to store
402 * the directory entry in hash order.
403 */
404struct fname {
405 __u32 hash;
406 __u32 minor_hash;
407 struct rb_node rb_hash;
408 struct fname *next;
409 __u32 inode;
410 __u8 name_len;
411 __u8 file_type;
412 char name[];
413};
414
415/*
416 * This functoin implements a non-recursive way of freeing all of the
417 * nodes in the red-black tree.
418 */
419static void free_rb_tree_fname(struct rb_root *root)
420{
421 struct fname *fname, *next;
422
423 rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash)
424 while (fname) {
425 struct fname *old = fname;
426 fname = fname->next;
427 kfree(old);
428 }
429
430 *root = RB_ROOT;
431}
432
433
434static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp,
435 loff_t pos)
436{
437 struct dir_private_info *p;
438
439 p = kzalloc(sizeof(*p), GFP_KERNEL);
440 if (!p)
441 return NULL;
442 p->curr_hash = pos2maj_hash(filp, pos);
443 p->curr_minor_hash = pos2min_hash(filp, pos);
444 return p;
445}
446
447void ext4_htree_free_dir_info(struct dir_private_info *p)
448{
449 free_rb_tree_fname(&p->root);
450 kfree(p);
451}
452
453/*
454 * Given a directory entry, enter it into the fname rb tree.
455 *
456 * When filename encryption is enabled, the dirent will hold the
457 * encrypted filename, while the htree will hold decrypted filename.
458 * The decrypted filename is passed in via ent_name. parameter.
459 */
460int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
461 __u32 minor_hash,
462 struct ext4_dir_entry_2 *dirent,
463 struct fscrypt_str *ent_name)
464{
465 struct rb_node **p, *parent = NULL;
466 struct fname *fname, *new_fn;
467 struct dir_private_info *info;
468 int len;
469
470 info = dir_file->private_data;
471 p = &info->root.rb_node;
472
473 /* Create and allocate the fname structure */
474 len = sizeof(struct fname) + ent_name->len + 1;
475 new_fn = kzalloc(len, GFP_KERNEL);
476 if (!new_fn)
477 return -ENOMEM;
478 new_fn->hash = hash;
479 new_fn->minor_hash = minor_hash;
480 new_fn->inode = le32_to_cpu(dirent->inode);
481 new_fn->name_len = ent_name->len;
482 new_fn->file_type = dirent->file_type;
483 memcpy(new_fn->name, ent_name->name, ent_name->len);
484
485 while (*p) {
486 parent = *p;
487 fname = rb_entry(parent, struct fname, rb_hash);
488
489 /*
490 * If the hash and minor hash match up, then we put
491 * them on a linked list. This rarely happens...
492 */
493 if ((new_fn->hash == fname->hash) &&
494 (new_fn->minor_hash == fname->minor_hash)) {
495 new_fn->next = fname->next;
496 fname->next = new_fn;
497 return 0;
498 }
499
500 if (new_fn->hash < fname->hash)
501 p = &(*p)->rb_left;
502 else if (new_fn->hash > fname->hash)
503 p = &(*p)->rb_right;
504 else if (new_fn->minor_hash < fname->minor_hash)
505 p = &(*p)->rb_left;
506 else /* if (new_fn->minor_hash > fname->minor_hash) */
507 p = &(*p)->rb_right;
508 }
509
510 rb_link_node(&new_fn->rb_hash, parent, p);
511 rb_insert_color(&new_fn->rb_hash, &info->root);
512 return 0;
513}
514
515
516
517/*
518 * This is a helper function for ext4_dx_readdir. It calls filldir
519 * for all entres on the fname linked list. (Normally there is only
520 * one entry on the linked list, unless there are 62 bit hash collisions.)
521 */
522static int call_filldir(struct file *file, struct dir_context *ctx,
523 struct fname *fname)
524{
525 struct dir_private_info *info = file->private_data;
526 struct inode *inode = file_inode(file);
527 struct super_block *sb = inode->i_sb;
528
529 if (!fname) {
530 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: "
531 "called with null fname?!?", __func__, __LINE__,
532 inode->i_ino, current->comm);
533 return 0;
534 }
535 ctx->pos = hash2pos(file, fname->hash, fname->minor_hash);
536 while (fname) {
537 if (!dir_emit(ctx, fname->name,
538 fname->name_len,
539 fname->inode,
540 get_dtype(sb, fname->file_type))) {
541 info->extra_fname = fname;
542 return 1;
543 }
544 fname = fname->next;
545 }
546 return 0;
547}
548
549static int ext4_dx_readdir(struct file *file, struct dir_context *ctx)
550{
551 struct dir_private_info *info = file->private_data;
552 struct inode *inode = file_inode(file);
553 struct fname *fname;
554 int ret = 0;
555
556 if (!info) {
557 info = ext4_htree_create_dir_info(file, ctx->pos);
558 if (!info)
559 return -ENOMEM;
560 file->private_data = info;
561 }
562
563 if (ctx->pos == ext4_get_htree_eof(file))
564 return 0; /* EOF */
565
566 /* Some one has messed with f_pos; reset the world */
567 if (info->last_pos != ctx->pos) {
568 free_rb_tree_fname(&info->root);
569 info->curr_node = NULL;
570 info->extra_fname = NULL;
571 info->curr_hash = pos2maj_hash(file, ctx->pos);
572 info->curr_minor_hash = pos2min_hash(file, ctx->pos);
573 }
574
575 /*
576 * If there are any leftover names on the hash collision
577 * chain, return them first.
578 */
579 if (info->extra_fname) {
580 if (call_filldir(file, ctx, info->extra_fname))
581 goto finished;
582 info->extra_fname = NULL;
583 goto next_node;
584 } else if (!info->curr_node)
585 info->curr_node = rb_first(&info->root);
586
587 while (1) {
588 /*
589 * Fill the rbtree if we have no more entries,
590 * or the inode has changed since we last read in the
591 * cached entries.
592 */
593 if ((!info->curr_node) ||
594 !inode_eq_iversion(inode, file->f_version)) {
595 info->curr_node = NULL;
596 free_rb_tree_fname(&info->root);
597 file->f_version = inode_query_iversion(inode);
598 ret = ext4_htree_fill_tree(file, info->curr_hash,
599 info->curr_minor_hash,
600 &info->next_hash);
601 if (ret < 0)
602 goto finished;
603 if (ret == 0) {
604 ctx->pos = ext4_get_htree_eof(file);
605 break;
606 }
607 info->curr_node = rb_first(&info->root);
608 }
609
610 fname = rb_entry(info->curr_node, struct fname, rb_hash);
611 info->curr_hash = fname->hash;
612 info->curr_minor_hash = fname->minor_hash;
613 if (call_filldir(file, ctx, fname))
614 break;
615 next_node:
616 info->curr_node = rb_next(info->curr_node);
617 if (info->curr_node) {
618 fname = rb_entry(info->curr_node, struct fname,
619 rb_hash);
620 info->curr_hash = fname->hash;
621 info->curr_minor_hash = fname->minor_hash;
622 } else {
623 if (info->next_hash == ~0) {
624 ctx->pos = ext4_get_htree_eof(file);
625 break;
626 }
627 info->curr_hash = info->next_hash;
628 info->curr_minor_hash = 0;
629 }
630 }
631finished:
632 info->last_pos = ctx->pos;
633 return ret < 0 ? ret : 0;
634}
635
636static int ext4_release_dir(struct inode *inode, struct file *filp)
637{
638 if (filp->private_data)
639 ext4_htree_free_dir_info(filp->private_data);
640
641 return 0;
642}
643
644int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf,
645 int buf_size)
646{
647 struct ext4_dir_entry_2 *de;
648 int rlen;
649 unsigned int offset = 0;
650 char *top;
651
652 de = (struct ext4_dir_entry_2 *)buf;
653 top = buf + buf_size;
654 while ((char *) de < top) {
655 if (ext4_check_dir_entry(dir, NULL, de, bh,
656 buf, buf_size, offset))
657 return -EFSCORRUPTED;
658 rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
659 de = (struct ext4_dir_entry_2 *)((char *)de + rlen);
660 offset += rlen;
661 }
662 if ((char *) de > top)
663 return -EFSCORRUPTED;
664
665 return 0;
666}
667
668const struct file_operations ext4_dir_operations = {
669 .llseek = ext4_dir_llseek,
670 .read = generic_read_dir,
671 .iterate_shared = ext4_readdir,
672 .unlocked_ioctl = ext4_ioctl,
673#ifdef CONFIG_COMPAT
674 .compat_ioctl = ext4_compat_ioctl,
675#endif
676 .fsync = ext4_sync_file,
677 .release = ext4_release_dir,
678};