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WSL2-Linux-Kernel
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WSL2-Linux-Kernel/fs/ext4/dir.c

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// SPDX-License-Identifier: GPL-2.0
/*
* linux/fs/ext4/dir.c
*
* Copyright (C) 1992, 1993, 1994, 1995
* Remy Card (card@masi.ibp.fr)
* Laboratoire MASI - Institut Blaise Pascal
* Universite Pierre et Marie Curie (Paris VI)
*
* from
*
* linux/fs/minix/dir.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* ext4 directory handling functions
*
* Big-endian to little-endian byte-swapping/bitmaps by
* David S. Miller (davem@caip.rutgers.edu), 1995
*
* Hash Tree Directory indexing (c) 2001 Daniel Phillips
*
*/
#include <linux/fs.h>
#include <linux/buffer_head.h>
#include <linux/slab.h>
#include <linux/iversion.h>
#include <linux/unicode.h>
#include "ext4.h"
#include "xattr.h"
static int ext4_dx_readdir(struct file *, struct dir_context *);
/**
* is_dx_dir() - check if a directory is using htree indexing
* @inode: directory inode
*
* Check if the given dir-inode refers to an htree-indexed directory
* (or a directory which could potentially get converted to use htree
* indexing).
*
* Return 1 if it is a dx dir, 0 if not
*/
static int is_dx_dir(struct inode *inode)
{
struct super_block *sb = inode->i_sb;
if (ext4_has_feature_dir_index(inode->i_sb) &&
((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) ||
((inode->i_size >> sb->s_blocksize_bits) == 1) ||
ext4_has_inline_data(inode)))
return 1;
return 0;
}
static bool is_fake_dir_entry(struct ext4_dir_entry_2 *de)
{
/* Check if . or .. , or skip if namelen is 0 */
if ((de->name_len > 0) && (de->name_len <= 2) && (de->name[0] == '.') &&
(de->name[1] == '.' || de->name[1] == '\0'))
return true;
/* Check if this is a csum entry */
if (de->file_type == EXT4_FT_DIR_CSUM)
return true;
return false;
}
/*
* Return 0 if the directory entry is OK, and 1 if there is a problem
*
* Note: this is the opposite of what ext2 and ext3 historically returned...
*
* bh passed here can be an inode block or a dir data block, depending
* on the inode inline data flag.
*/
int __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)
{
const char *error_msg = NULL;
const int rlen = ext4_rec_len_from_disk(de->rec_len,
dir->i_sb->s_blocksize);
const int next_offset = ((char *) de - buf) + rlen;
bool fake = is_fake_dir_entry(de);
bool has_csum = ext4_has_metadata_csum(dir->i_sb);
if (unlikely(rlen < ext4_dir_rec_len(1, fake ? NULL : dir)))
error_msg = "rec_len is smaller than minimal";
else if (unlikely(rlen % 4 != 0))
error_msg = "rec_len % 4 != 0";
else if (unlikely(rlen < ext4_dir_rec_len(de->name_len,
fake ? NULL : dir)))
error_msg = "rec_len is too small for name_len";
else if (unlikely(next_offset > size))
error_msg = "directory entry overrun";
else if (unlikely(next_offset > size - ext4_dir_rec_len(1,
has_csum ? NULL : dir) &&
next_offset != size))
error_msg = "directory entry too close to block end";
else if (unlikely(le32_to_cpu(de->inode) >
le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)))
error_msg = "inode out of bounds";
else
return 0;
if (filp)
ext4_error_file(filp, function, line, bh->b_blocknr,
"bad entry in directory: %s - offset=%u, "
"inode=%u, rec_len=%d, size=%d fake=%d",
error_msg, offset, le32_to_cpu(de->inode),
rlen, size, fake);
else
ext4_error_inode(dir, function, line, bh->b_blocknr,
"bad entry in directory: %s - offset=%u, "
"inode=%u, rec_len=%d, size=%d fake=%d",
error_msg, offset, le32_to_cpu(de->inode),
rlen, size, fake);
return 1;
}
static int ext4_readdir(struct file *file, struct dir_context *ctx)
{
unsigned int offset;
int i;
struct ext4_dir_entry_2 *de;
int err;
struct inode *inode = file_inode(file);
struct super_block *sb = inode->i_sb;
struct buffer_head *bh = NULL;
struct fscrypt_str fstr = FSTR_INIT(NULL, 0);
err = fscrypt_prepare_readdir(inode);
if (err)
return err;
if (is_dx_dir(inode)) {
err = ext4_dx_readdir(file, ctx);
if (err != ERR_BAD_DX_DIR)
return err;
/* Can we just clear INDEX flag to ignore htree information? */
if (!ext4_has_metadata_csum(sb)) {
/*
* We don't set the inode dirty flag since it's not
* critical that it gets flushed back to the disk.
*/
ext4_clear_inode_flag(inode, EXT4_INODE_INDEX);
}
}
if (ext4_has_inline_data(inode)) {
int has_inline_data = 1;
err = ext4_read_inline_dir(file, ctx,
&has_inline_data);
if (has_inline_data)
return err;
}
if (IS_ENCRYPTED(inode)) {
err = fscrypt_fname_alloc_buffer(EXT4_NAME_LEN, &fstr);
if (err < 0)
return err;
}
while (ctx->pos < inode->i_size) {
struct ext4_map_blocks map;
if (fatal_signal_pending(current)) {
err = -ERESTARTSYS;
goto errout;
}
cond_resched();
offset = ctx->pos & (sb->s_blocksize - 1);
map.m_lblk = ctx->pos >> EXT4_BLOCK_SIZE_BITS(sb);
map.m_len = 1;
err = ext4_map_blocks(NULL, inode, &map, 0);
if (err == 0) {
/* m_len should never be zero but let's avoid
* an infinite loop if it somehow is */
if (map.m_len == 0)
map.m_len = 1;
ctx->pos += map.m_len * sb->s_blocksize;
continue;
}
if (err > 0) {
pgoff_t index = map.m_pblk >>
(PAGE_SHIFT - inode->i_blkbits);
if (!ra_has_index(&file->f_ra, index))
page_cache_sync_readahead(
sb->s_bdev->bd_inode->i_mapping,
&file->f_ra, file,
index, 1);
file->f_ra.prev_pos = (loff_t)index << PAGE_SHIFT;
bh = ext4_bread(NULL, inode, map.m_lblk, 0);
if (IS_ERR(bh)) {
err = PTR_ERR(bh);
bh = NULL;
goto errout;
}
}
if (!bh) {
/* corrupt size? Maybe no more blocks to read */
if (ctx->pos > inode->i_blocks << 9)
break;
ctx->pos += sb->s_blocksize - offset;
continue;
}
/* Check the checksum */
if (!buffer_verified(bh) &&
!ext4_dirblock_csum_verify(inode, bh)) {
EXT4_ERROR_FILE(file, 0, "directory fails checksum "
"at offset %llu",
(unsigned long long)ctx->pos);
ctx->pos += sb->s_blocksize - offset;
brelse(bh);
bh = NULL;
continue;
}
set_buffer_verified(bh);
/* If the dir block has changed since the last call to
* readdir(2), then we might be pointing to an invalid
* dirent right now. Scan from the start of the block
* to make sure. */
if (!inode_eq_iversion(inode, file->f_version)) {
for (i = 0; i < sb->s_blocksize && i < offset; ) {
de = (struct ext4_dir_entry_2 *)
(bh->b_data + i);
/* It's too expensive to do a full
* dirent test each time round this
* loop, but we do have to test at
* least that it is non-zero. A
* failure will be detected in the
* dirent test below. */
if (ext4_rec_len_from_disk(de->rec_len,
sb->s_blocksize) < ext4_dir_rec_len(1,
inode))
break;
i += ext4_rec_len_from_disk(de->rec_len,
sb->s_blocksize);
}
offset = i;
ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1))
| offset;
file->f_version = inode_query_iversion(inode);
}
while (ctx->pos < inode->i_size
&& offset < sb->s_blocksize) {
de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
if (ext4_check_dir_entry(inode, file, de, bh,
bh->b_data, bh->b_size,
offset)) {
/*
* On error, skip to the next block
*/
ctx->pos = (ctx->pos |
(sb->s_blocksize - 1)) + 1;
break;
}
offset += ext4_rec_len_from_disk(de->rec_len,
sb->s_blocksize);
if (le32_to_cpu(de->inode)) {
if (!IS_ENCRYPTED(inode)) {
if (!dir_emit(ctx, de->name,
de->name_len,
le32_to_cpu(de->inode),
get_dtype(sb, de->file_type)))
goto done;
} else {
int save_len = fstr.len;
struct fscrypt_str de_name =
FSTR_INIT(de->name,
de->name_len);
/* Directory is encrypted */
err = fscrypt_fname_disk_to_usr(inode,
EXT4_DIRENT_HASH(de),
EXT4_DIRENT_MINOR_HASH(de),
&de_name, &fstr);
de_name = fstr;
fstr.len = save_len;
if (err)
goto errout;
if (!dir_emit(ctx,
de_name.name, de_name.len,
le32_to_cpu(de->inode),
get_dtype(sb, de->file_type)))
goto done;
}
}
ctx->pos += ext4_rec_len_from_disk(de->rec_len,
sb->s_blocksize);
}
if ((ctx->pos < inode->i_size) && !dir_relax_shared(inode))
goto done;
brelse(bh);
bh = NULL;
offset = 0;
}
done:
err = 0;
errout:
fscrypt_fname_free_buffer(&fstr);
brelse(bh);
return err;
}
static inline int is_32bit_api(void)
{
#ifdef CONFIG_COMPAT
return in_compat_syscall();
#else
return (BITS_PER_LONG == 32);
#endif
}
/*
* These functions convert from the major/minor hash to an f_pos
* value for dx directories
*
* Upper layer (for example NFS) should specify FMODE_32BITHASH or
* FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted
* directly on both 32-bit and 64-bit nodes, under such case, neither
* FMODE_32BITHASH nor FMODE_64BITHASH is specified.
*/
static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor)
{
if ((filp->f_mode & FMODE_32BITHASH) ||
(!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
return major >> 1;
else
return ((__u64)(major >> 1) << 32) | (__u64)minor;
}
static inline __u32 pos2maj_hash(struct file *filp, loff_t pos)
{
if ((filp->f_mode & FMODE_32BITHASH) ||
(!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
return (pos << 1) & 0xffffffff;
else
return ((pos >> 32) << 1) & 0xffffffff;
}
static inline __u32 pos2min_hash(struct file *filp, loff_t pos)
{
if ((filp->f_mode & FMODE_32BITHASH) ||
(!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
return 0;
else
return pos & 0xffffffff;
}
/*
* Return 32- or 64-bit end-of-file for dx directories
*/
static inline loff_t ext4_get_htree_eof(struct file *filp)
{
if ((filp->f_mode & FMODE_32BITHASH) ||
(!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
return EXT4_HTREE_EOF_32BIT;
else
return EXT4_HTREE_EOF_64BIT;
}
/*
* ext4_dir_llseek() calls generic_file_llseek_size to handle htree
* directories, where the "offset" is in terms of the filename hash
* value instead of the byte offset.
*
* Because we may return a 64-bit hash that is well beyond offset limits,
* we need to pass the max hash as the maximum allowable offset in
* the htree directory case.
*
* For non-htree, ext4_llseek already chooses the proper max offset.
*/
static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence)
{
struct inode *inode = file->f_mapping->host;
int dx_dir = is_dx_dir(inode);
loff_t ret, htree_max = ext4_get_htree_eof(file);
if (likely(dx_dir))
ret = generic_file_llseek_size(file, offset, whence,
htree_max, htree_max);
else
ret = ext4_llseek(file, offset, whence);
file->f_version = inode_peek_iversion(inode) - 1;
return ret;
}
/*
* This structure holds the nodes of the red-black tree used to store
* the directory entry in hash order.
*/
struct fname {
__u32 hash;
__u32 minor_hash;
struct rb_node rb_hash;
struct fname *next;
__u32 inode;
__u8 name_len;
__u8 file_type;
char name[];
};
/*
* This functoin implements a non-recursive way of freeing all of the
* nodes in the red-black tree.
*/
static void free_rb_tree_fname(struct rb_root *root)
{
struct fname *fname, *next;
rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash)
while (fname) {
struct fname *old = fname;
fname = fname->next;
kfree(old);
}
*root = RB_ROOT;
}
static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp,
loff_t pos)
{
struct dir_private_info *p;
p = kzalloc(sizeof(*p), GFP_KERNEL);
if (!p)
return NULL;
p->curr_hash = pos2maj_hash(filp, pos);
p->curr_minor_hash = pos2min_hash(filp, pos);
return p;
}
void ext4_htree_free_dir_info(struct dir_private_info *p)
{
free_rb_tree_fname(&p->root);
kfree(p);
}
/*
* Given a directory entry, enter it into the fname rb tree.
*
* When filename encryption is enabled, the dirent will hold the
* encrypted filename, while the htree will hold decrypted filename.
* The decrypted filename is passed in via ent_name. parameter.
*/
int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
__u32 minor_hash,
struct ext4_dir_entry_2 *dirent,
struct fscrypt_str *ent_name)
{
struct rb_node **p, *parent = NULL;
struct fname *fname, *new_fn;
struct dir_private_info *info;
int len;
info = dir_file->private_data;
p = &info->root.rb_node;
/* Create and allocate the fname structure */
len = sizeof(struct fname) + ent_name->len + 1;
new_fn = kzalloc(len, GFP_KERNEL);
if (!new_fn)
return -ENOMEM;
new_fn->hash = hash;
new_fn->minor_hash = minor_hash;
new_fn->inode = le32_to_cpu(dirent->inode);
new_fn->name_len = ent_name->len;
new_fn->file_type = dirent->file_type;
memcpy(new_fn->name, ent_name->name, ent_name->len);
while (*p) {
parent = *p;
fname = rb_entry(parent, struct fname, rb_hash);
/*
* If the hash and minor hash match up, then we put
* them on a linked list. This rarely happens...
*/
if ((new_fn->hash == fname->hash) &&
(new_fn->minor_hash == fname->minor_hash)) {
new_fn->next = fname->next;
fname->next = new_fn;
return 0;
}
if (new_fn->hash < fname->hash)
p = &(*p)->rb_left;
else if (new_fn->hash > fname->hash)
p = &(*p)->rb_right;
else if (new_fn->minor_hash < fname->minor_hash)
p = &(*p)->rb_left;
else /* if (new_fn->minor_hash > fname->minor_hash) */
p = &(*p)->rb_right;
}
rb_link_node(&new_fn->rb_hash, parent, p);
rb_insert_color(&new_fn->rb_hash, &info->root);
return 0;
}
/*
* This is a helper function for ext4_dx_readdir. It calls filldir
* for all entres on the fname linked list. (Normally there is only
* one entry on the linked list, unless there are 62 bit hash collisions.)
*/
static int call_filldir(struct file *file, struct dir_context *ctx,
struct fname *fname)
{
struct dir_private_info *info = file->private_data;
struct inode *inode = file_inode(file);
struct super_block *sb = inode->i_sb;
if (!fname) {
ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: "
"called with null fname?!?", __func__, __LINE__,
inode->i_ino, current->comm);
return 0;
}
ctx->pos = hash2pos(file, fname->hash, fname->minor_hash);
while (fname) {
if (!dir_emit(ctx, fname->name,
fname->name_len,
fname->inode,
get_dtype(sb, fname->file_type))) {
info->extra_fname = fname;
return 1;
}
fname = fname->next;
}
return 0;
}
static int ext4_dx_readdir(struct file *file, struct dir_context *ctx)
{
struct dir_private_info *info = file->private_data;
struct inode *inode = file_inode(file);
struct fname *fname;
int ret;
if (!info) {
info = ext4_htree_create_dir_info(file, ctx->pos);
if (!info)
return -ENOMEM;
file->private_data = info;
}
if (ctx->pos == ext4_get_htree_eof(file))
return 0; /* EOF */
/* Some one has messed with f_pos; reset the world */
if (info->last_pos != ctx->pos) {
free_rb_tree_fname(&info->root);
info->curr_node = NULL;
info->extra_fname = NULL;
info->curr_hash = pos2maj_hash(file, ctx->pos);
info->curr_minor_hash = pos2min_hash(file, ctx->pos);
}
/*
* If there are any leftover names on the hash collision
* chain, return them first.
*/
if (info->extra_fname) {
if (call_filldir(file, ctx, info->extra_fname))
goto finished;
info->extra_fname = NULL;
goto next_node;
} else if (!info->curr_node)
info->curr_node = rb_first(&info->root);
while (1) {
/*
* Fill the rbtree if we have no more entries,
* or the inode has changed since we last read in the
* cached entries.
*/
if ((!info->curr_node) ||
!inode_eq_iversion(inode, file->f_version)) {
info->curr_node = NULL;
free_rb_tree_fname(&info->root);
file->f_version = inode_query_iversion(inode);
ret = ext4_htree_fill_tree(file, info->curr_hash,
info->curr_minor_hash,
&info->next_hash);
if (ret < 0)
return ret;
if (ret == 0) {
ctx->pos = ext4_get_htree_eof(file);
break;
}
info->curr_node = rb_first(&info->root);
}
fname = rb_entry(info->curr_node, struct fname, rb_hash);
info->curr_hash = fname->hash;
info->curr_minor_hash = fname->minor_hash;
if (call_filldir(file, ctx, fname))
break;
next_node:
info->curr_node = rb_next(info->curr_node);
if (info->curr_node) {
fname = rb_entry(info->curr_node, struct fname,
rb_hash);
info->curr_hash = fname->hash;
info->curr_minor_hash = fname->minor_hash;
} else {
if (info->next_hash == ~0) {
ctx->pos = ext4_get_htree_eof(file);
break;
}
info->curr_hash = info->next_hash;
info->curr_minor_hash = 0;
}
}
finished:
info->last_pos = ctx->pos;
return 0;
}
static int ext4_release_dir(struct inode *inode, struct file *filp)
{
if (filp->private_data)
ext4_htree_free_dir_info(filp->private_data);
return 0;
}
int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf,
int buf_size)
{
struct ext4_dir_entry_2 *de;
int rlen;
unsigned int offset = 0;
char *top;
de = (struct ext4_dir_entry_2 *)buf;
top = buf + buf_size;
while ((char *) de < top) {
if (ext4_check_dir_entry(dir, NULL, de, bh,
buf, buf_size, offset))
return -EFSCORRUPTED;
rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
de = (struct ext4_dir_entry_2 *)((char *)de + rlen);
offset += rlen;
}
if ((char *) de > top)
return -EFSCORRUPTED;
return 0;
}
const struct file_operations ext4_dir_operations = {
.llseek = ext4_dir_llseek,
.read = generic_read_dir,
.iterate_shared = ext4_readdir,
.unlocked_ioctl = ext4_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = ext4_compat_ioctl,
#endif
.fsync = ext4_sync_file,
.release = ext4_release_dir,
};
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