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A specially crafted file system can trick empty_inline_dir() into reading past the last valid entry in a inline directory, and then run into the end of xattr marker. This will trigger a divide by zero fault. Fix this by using the size of the inline directory instead of dir->i_size. Also clean up error reporting in __ext4_check_dir_entry so that the message is clearer and more understandable --- and avoids the division by zero trap if the size passed in is zero. (I'm not sure why we coded it that way in the first place; printing offset % size is actually more confusing and less useful.) https://bugzilla.kernel.org/show_bug.cgi?id=200933 Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reported-by: Wen Xu <wen.xu@gatech.edu> Cc: stable@vger.kernel.org
665 lines
17 KiB
C
665 lines
17 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* linux/fs/ext4/dir.c
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*
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* Copyright (C) 1992, 1993, 1994, 1995
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* Remy Card (card@masi.ibp.fr)
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* Laboratoire MASI - Institut Blaise Pascal
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* Universite Pierre et Marie Curie (Paris VI)
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*
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* from
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*
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* linux/fs/minix/dir.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*
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* ext4 directory handling functions
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*
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* Big-endian to little-endian byte-swapping/bitmaps by
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* David S. Miller (davem@caip.rutgers.edu), 1995
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*
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* Hash Tree Directory indexing (c) 2001 Daniel Phillips
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*
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*/
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#include <linux/fs.h>
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#include <linux/buffer_head.h>
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#include <linux/slab.h>
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#include <linux/iversion.h>
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#include "ext4.h"
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#include "xattr.h"
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static int ext4_dx_readdir(struct file *, struct dir_context *);
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/**
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* Check if the given dir-inode refers to an htree-indexed directory
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* (or a directory which could potentially get converted to use htree
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* indexing).
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*
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* Return 1 if it is a dx dir, 0 if not
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*/
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static int is_dx_dir(struct inode *inode)
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{
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struct super_block *sb = inode->i_sb;
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if (ext4_has_feature_dir_index(inode->i_sb) &&
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((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) ||
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((inode->i_size >> sb->s_blocksize_bits) == 1) ||
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ext4_has_inline_data(inode)))
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return 1;
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return 0;
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}
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/*
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* Return 0 if the directory entry is OK, and 1 if there is a problem
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*
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* Note: this is the opposite of what ext2 and ext3 historically returned...
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*
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* bh passed here can be an inode block or a dir data block, depending
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* on the inode inline data flag.
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*/
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int __ext4_check_dir_entry(const char *function, unsigned int line,
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struct inode *dir, struct file *filp,
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struct ext4_dir_entry_2 *de,
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struct buffer_head *bh, char *buf, int size,
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unsigned int offset)
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{
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const char *error_msg = NULL;
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const int rlen = ext4_rec_len_from_disk(de->rec_len,
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dir->i_sb->s_blocksize);
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if (unlikely(rlen < EXT4_DIR_REC_LEN(1)))
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error_msg = "rec_len is smaller than minimal";
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else if (unlikely(rlen % 4 != 0))
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error_msg = "rec_len % 4 != 0";
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else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len)))
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error_msg = "rec_len is too small for name_len";
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else if (unlikely(((char *) de - buf) + rlen > size))
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error_msg = "directory entry overrun";
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else if (unlikely(le32_to_cpu(de->inode) >
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le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)))
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error_msg = "inode out of bounds";
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else
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return 0;
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if (filp)
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ext4_error_file(filp, function, line, bh->b_blocknr,
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"bad entry in directory: %s - offset=%u, "
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"inode=%u, rec_len=%d, name_len=%d, size=%d",
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error_msg, offset, le32_to_cpu(de->inode),
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rlen, de->name_len, size);
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else
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ext4_error_inode(dir, function, line, bh->b_blocknr,
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"bad entry in directory: %s - offset=%u, "
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"inode=%u, rec_len=%d, name_len=%d, size=%d",
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error_msg, offset, le32_to_cpu(de->inode),
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rlen, de->name_len, size);
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return 1;
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}
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static int ext4_readdir(struct file *file, struct dir_context *ctx)
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{
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unsigned int offset;
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int i;
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struct ext4_dir_entry_2 *de;
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int err;
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struct inode *inode = file_inode(file);
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struct super_block *sb = inode->i_sb;
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struct buffer_head *bh = NULL;
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int dir_has_error = 0;
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struct fscrypt_str fstr = FSTR_INIT(NULL, 0);
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if (ext4_encrypted_inode(inode)) {
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err = fscrypt_get_encryption_info(inode);
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if (err && err != -ENOKEY)
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return err;
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}
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if (is_dx_dir(inode)) {
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err = ext4_dx_readdir(file, ctx);
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if (err != ERR_BAD_DX_DIR) {
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return err;
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}
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/*
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* We don't set the inode dirty flag since it's not
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* critical that it get flushed back to the disk.
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*/
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ext4_clear_inode_flag(file_inode(file),
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EXT4_INODE_INDEX);
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}
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if (ext4_has_inline_data(inode)) {
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int has_inline_data = 1;
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err = ext4_read_inline_dir(file, ctx,
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&has_inline_data);
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if (has_inline_data)
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return err;
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}
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if (ext4_encrypted_inode(inode)) {
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err = fscrypt_fname_alloc_buffer(inode, EXT4_NAME_LEN, &fstr);
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if (err < 0)
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return err;
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}
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offset = ctx->pos & (sb->s_blocksize - 1);
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while (ctx->pos < inode->i_size) {
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struct ext4_map_blocks map;
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if (fatal_signal_pending(current)) {
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err = -ERESTARTSYS;
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goto errout;
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}
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cond_resched();
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map.m_lblk = ctx->pos >> EXT4_BLOCK_SIZE_BITS(sb);
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map.m_len = 1;
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err = ext4_map_blocks(NULL, inode, &map, 0);
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if (err > 0) {
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pgoff_t index = map.m_pblk >>
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(PAGE_SHIFT - inode->i_blkbits);
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if (!ra_has_index(&file->f_ra, index))
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page_cache_sync_readahead(
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sb->s_bdev->bd_inode->i_mapping,
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&file->f_ra, file,
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index, 1);
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file->f_ra.prev_pos = (loff_t)index << PAGE_SHIFT;
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bh = ext4_bread(NULL, inode, map.m_lblk, 0);
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if (IS_ERR(bh)) {
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err = PTR_ERR(bh);
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bh = NULL;
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goto errout;
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}
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}
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if (!bh) {
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if (!dir_has_error) {
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EXT4_ERROR_FILE(file, 0,
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"directory contains a "
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"hole at offset %llu",
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(unsigned long long) ctx->pos);
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dir_has_error = 1;
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}
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/* corrupt size? Maybe no more blocks to read */
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if (ctx->pos > inode->i_blocks << 9)
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break;
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ctx->pos += sb->s_blocksize - offset;
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continue;
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}
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/* Check the checksum */
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if (!buffer_verified(bh) &&
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!ext4_dirent_csum_verify(inode,
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(struct ext4_dir_entry *)bh->b_data)) {
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EXT4_ERROR_FILE(file, 0, "directory fails checksum "
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"at offset %llu",
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(unsigned long long)ctx->pos);
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ctx->pos += sb->s_blocksize - offset;
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brelse(bh);
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bh = NULL;
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continue;
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}
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set_buffer_verified(bh);
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/* If the dir block has changed since the last call to
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* readdir(2), then we might be pointing to an invalid
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* dirent right now. Scan from the start of the block
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* to make sure. */
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if (!inode_eq_iversion(inode, file->f_version)) {
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for (i = 0; i < sb->s_blocksize && i < offset; ) {
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de = (struct ext4_dir_entry_2 *)
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(bh->b_data + i);
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/* It's too expensive to do a full
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* dirent test each time round this
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* loop, but we do have to test at
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* least that it is non-zero. A
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* failure will be detected in the
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* dirent test below. */
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if (ext4_rec_len_from_disk(de->rec_len,
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sb->s_blocksize) < EXT4_DIR_REC_LEN(1))
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break;
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i += ext4_rec_len_from_disk(de->rec_len,
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sb->s_blocksize);
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}
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offset = i;
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ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1))
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| offset;
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file->f_version = inode_query_iversion(inode);
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}
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while (ctx->pos < inode->i_size
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&& offset < sb->s_blocksize) {
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de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
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if (ext4_check_dir_entry(inode, file, de, bh,
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bh->b_data, bh->b_size,
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offset)) {
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/*
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* On error, skip to the next block
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*/
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ctx->pos = (ctx->pos |
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(sb->s_blocksize - 1)) + 1;
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break;
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}
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offset += ext4_rec_len_from_disk(de->rec_len,
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sb->s_blocksize);
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if (le32_to_cpu(de->inode)) {
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if (!ext4_encrypted_inode(inode)) {
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if (!dir_emit(ctx, de->name,
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de->name_len,
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le32_to_cpu(de->inode),
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get_dtype(sb, de->file_type)))
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goto done;
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} else {
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int save_len = fstr.len;
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struct fscrypt_str de_name =
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FSTR_INIT(de->name,
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de->name_len);
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/* Directory is encrypted */
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err = fscrypt_fname_disk_to_usr(inode,
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0, 0, &de_name, &fstr);
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de_name = fstr;
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fstr.len = save_len;
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if (err)
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goto errout;
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if (!dir_emit(ctx,
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de_name.name, de_name.len,
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le32_to_cpu(de->inode),
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get_dtype(sb, de->file_type)))
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goto done;
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}
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}
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ctx->pos += ext4_rec_len_from_disk(de->rec_len,
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sb->s_blocksize);
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}
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if ((ctx->pos < inode->i_size) && !dir_relax_shared(inode))
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goto done;
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brelse(bh);
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bh = NULL;
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offset = 0;
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}
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done:
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err = 0;
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errout:
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#ifdef CONFIG_EXT4_FS_ENCRYPTION
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fscrypt_fname_free_buffer(&fstr);
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#endif
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brelse(bh);
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return err;
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}
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static inline int is_32bit_api(void)
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{
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#ifdef CONFIG_COMPAT
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return in_compat_syscall();
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#else
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return (BITS_PER_LONG == 32);
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#endif
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}
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/*
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* These functions convert from the major/minor hash to an f_pos
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* value for dx directories
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*
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* Upper layer (for example NFS) should specify FMODE_32BITHASH or
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* FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted
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* directly on both 32-bit and 64-bit nodes, under such case, neither
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* FMODE_32BITHASH nor FMODE_64BITHASH is specified.
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*/
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static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor)
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{
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if ((filp->f_mode & FMODE_32BITHASH) ||
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(!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
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return major >> 1;
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else
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return ((__u64)(major >> 1) << 32) | (__u64)minor;
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}
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static inline __u32 pos2maj_hash(struct file *filp, loff_t pos)
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{
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if ((filp->f_mode & FMODE_32BITHASH) ||
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(!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
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return (pos << 1) & 0xffffffff;
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else
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return ((pos >> 32) << 1) & 0xffffffff;
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}
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static inline __u32 pos2min_hash(struct file *filp, loff_t pos)
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{
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if ((filp->f_mode & FMODE_32BITHASH) ||
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(!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
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return 0;
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else
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return pos & 0xffffffff;
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}
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/*
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* Return 32- or 64-bit end-of-file for dx directories
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*/
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static inline loff_t ext4_get_htree_eof(struct file *filp)
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{
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if ((filp->f_mode & FMODE_32BITHASH) ||
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(!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
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return EXT4_HTREE_EOF_32BIT;
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else
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return EXT4_HTREE_EOF_64BIT;
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}
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/*
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* ext4_dir_llseek() calls generic_file_llseek_size to handle htree
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* directories, where the "offset" is in terms of the filename hash
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* value instead of the byte offset.
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*
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* Because we may return a 64-bit hash that is well beyond offset limits,
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* we need to pass the max hash as the maximum allowable offset in
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* the htree directory case.
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*
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* For non-htree, ext4_llseek already chooses the proper max offset.
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*/
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static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence)
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{
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struct inode *inode = file->f_mapping->host;
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int dx_dir = is_dx_dir(inode);
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loff_t ret, htree_max = ext4_get_htree_eof(file);
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if (likely(dx_dir))
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ret = generic_file_llseek_size(file, offset, whence,
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htree_max, htree_max);
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else
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ret = ext4_llseek(file, offset, whence);
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file->f_version = inode_peek_iversion(inode) - 1;
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return ret;
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}
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/*
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* This structure holds the nodes of the red-black tree used to store
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* the directory entry in hash order.
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*/
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struct fname {
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__u32 hash;
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__u32 minor_hash;
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struct rb_node rb_hash;
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struct fname *next;
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__u32 inode;
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__u8 name_len;
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__u8 file_type;
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char name[0];
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};
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/*
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* This functoin implements a non-recursive way of freeing all of the
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* nodes in the red-black tree.
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*/
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static void free_rb_tree_fname(struct rb_root *root)
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{
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struct fname *fname, *next;
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rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash)
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while (fname) {
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struct fname *old = fname;
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fname = fname->next;
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kfree(old);
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}
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*root = RB_ROOT;
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}
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static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp,
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loff_t pos)
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{
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struct dir_private_info *p;
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p = kzalloc(sizeof(*p), GFP_KERNEL);
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if (!p)
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return NULL;
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p->curr_hash = pos2maj_hash(filp, pos);
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p->curr_minor_hash = pos2min_hash(filp, pos);
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return p;
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}
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void ext4_htree_free_dir_info(struct dir_private_info *p)
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{
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free_rb_tree_fname(&p->root);
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kfree(p);
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}
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/*
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* Given a directory entry, enter it into the fname rb tree.
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*
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* When filename encryption is enabled, the dirent will hold the
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* encrypted filename, while the htree will hold decrypted filename.
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* The decrypted filename is passed in via ent_name. parameter.
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*/
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int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
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__u32 minor_hash,
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struct ext4_dir_entry_2 *dirent,
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struct fscrypt_str *ent_name)
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{
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struct rb_node **p, *parent = NULL;
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struct fname *fname, *new_fn;
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struct dir_private_info *info;
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int len;
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info = dir_file->private_data;
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p = &info->root.rb_node;
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/* Create and allocate the fname structure */
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len = sizeof(struct fname) + ent_name->len + 1;
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new_fn = kzalloc(len, GFP_KERNEL);
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if (!new_fn)
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return -ENOMEM;
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new_fn->hash = hash;
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new_fn->minor_hash = minor_hash;
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new_fn->inode = le32_to_cpu(dirent->inode);
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new_fn->name_len = ent_name->len;
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new_fn->file_type = dirent->file_type;
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memcpy(new_fn->name, ent_name->name, ent_name->len);
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new_fn->name[ent_name->len] = 0;
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while (*p) {
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parent = *p;
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fname = rb_entry(parent, struct fname, rb_hash);
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/*
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* If the hash and minor hash match up, then we put
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* them on a linked list. This rarely happens...
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*/
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if ((new_fn->hash == fname->hash) &&
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(new_fn->minor_hash == fname->minor_hash)) {
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new_fn->next = fname->next;
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fname->next = new_fn;
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return 0;
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}
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if (new_fn->hash < fname->hash)
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p = &(*p)->rb_left;
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else if (new_fn->hash > fname->hash)
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p = &(*p)->rb_right;
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else if (new_fn->minor_hash < fname->minor_hash)
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|
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_dir_open(struct inode * inode, struct file * filp)
|
|
{
|
|
if (ext4_encrypted_inode(inode))
|
|
return fscrypt_get_encryption_info(inode) ? -EACCES : 0;
|
|
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,
|
|
.open = ext4_dir_open,
|
|
.release = ext4_release_dir,
|
|
};
|