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linux/fs/squashfs/inode.c
Phillip Lougher 3d4a1c80c4 Squashfs: fix i_blocks calculation with extended regular files 
The le64_to_cpu() forces the calculation to be unsigned, with
the effect that it can underflow leading to an incorrect large
value.

This bug only triggers in rare(ish) circumstances, an empty file
encoded as an extended regular file or a completely sparse file.
Normally empty files are encoded as a regular file rather than as
an extended regular file (and the regular file i_blocks calculation
doesn't have this bug).  To save space regular file inodes are
optimised to encode the most commonly occurring files.  Less
common regular files are encoded using extended regular file inodes
which contain extra information.

Empty files with nlinks greater than 1, and or empty files
with extended attributes are encoded using extended regular file
inodes and they will hit this bug.

Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
2012-01-03 04:00:43 +00:00

426 lines
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/*
* Squashfs - a compressed read only filesystem for Linux
*
* Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
* Phillip Lougher <phillip@squashfs.org.uk>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2,
* or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* inode.c
*/
/*
* This file implements code to create and read inodes from disk.
*
* Inodes in Squashfs are identified by a 48-bit inode which encodes the
* location of the compressed metadata block containing the inode, and the byte
* offset into that block where the inode is placed (<block, offset>).
*
* To maximise compression there are different inodes for each file type
* (regular file, directory, device, etc.), the inode contents and length
* varying with the type.
*
* To further maximise compression, two types of regular file inode and
* directory inode are defined: inodes optimised for frequently occurring
* regular files and directories, and extended types where extra
* information has to be stored.
*/
#include <linux/fs.h>
#include <linux/vfs.h>
#include <linux/xattr.h>
#include "squashfs_fs.h"
#include "squashfs_fs_sb.h"
#include "squashfs_fs_i.h"
#include "squashfs.h"
#include "xattr.h"
/*
* Initialise VFS inode with the base inode information common to all
* Squashfs inode types. Sqsh_ino contains the unswapped base inode
* off disk.
*/
static int squashfs_new_inode(struct super_block *sb, struct inode *inode,
struct squashfs_base_inode *sqsh_ino)
{
int err;
err = squashfs_get_id(sb, le16_to_cpu(sqsh_ino->uid), &inode->i_uid);
if (err)
return err;
err = squashfs_get_id(sb, le16_to_cpu(sqsh_ino->guid), &inode->i_gid);
if (err)
return err;
inode->i_ino = le32_to_cpu(sqsh_ino->inode_number);
inode->i_mtime.tv_sec = le32_to_cpu(sqsh_ino->mtime);
inode->i_atime.tv_sec = inode->i_mtime.tv_sec;
inode->i_ctime.tv_sec = inode->i_mtime.tv_sec;
inode->i_mode = le16_to_cpu(sqsh_ino->mode);
inode->i_size = 0;
return err;
}
struct inode *squashfs_iget(struct super_block *sb, long long ino,
unsigned int ino_number)
{
struct inode *inode = iget_locked(sb, ino_number);
int err;
TRACE("Entered squashfs_iget\n");
if (!inode)
return ERR_PTR(-ENOMEM);
if (!(inode->i_state & I_NEW))
return inode;
err = squashfs_read_inode(inode, ino);
if (err) {
iget_failed(inode);
return ERR_PTR(err);
}
unlock_new_inode(inode);
return inode;
}
/*
* Initialise VFS inode by reading inode from inode table (compressed
* metadata). The format and amount of data read depends on type.
*/
int squashfs_read_inode(struct inode *inode, long long ino)
{
struct super_block *sb = inode->i_sb;
struct squashfs_sb_info *msblk = sb->s_fs_info;
u64 block = SQUASHFS_INODE_BLK(ino) + msblk->inode_table;
int err, type, offset = SQUASHFS_INODE_OFFSET(ino);
union squashfs_inode squashfs_ino;
struct squashfs_base_inode *sqshb_ino = &squashfs_ino.base;
int xattr_id = SQUASHFS_INVALID_XATTR;
TRACE("Entered squashfs_read_inode\n");
/*
* Read inode base common to all inode types.
*/
err = squashfs_read_metadata(sb, sqshb_ino, &block,
&offset, sizeof(*sqshb_ino));
if (err < 0)
goto failed_read;
err = squashfs_new_inode(sb, inode, sqshb_ino);
if (err)
goto failed_read;
block = SQUASHFS_INODE_BLK(ino) + msblk->inode_table;
offset = SQUASHFS_INODE_OFFSET(ino);
type = le16_to_cpu(sqshb_ino->inode_type);
switch (type) {
case SQUASHFS_REG_TYPE: {
unsigned int frag_offset, frag;
int frag_size;
u64 frag_blk;
struct squashfs_reg_inode *sqsh_ino = &squashfs_ino.reg;
err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
sizeof(*sqsh_ino));
if (err < 0)
goto failed_read;
frag = le32_to_cpu(sqsh_ino->fragment);
if (frag != SQUASHFS_INVALID_FRAG) {
frag_offset = le32_to_cpu(sqsh_ino->offset);
frag_size = squashfs_frag_lookup(sb, frag, &frag_blk);
if (frag_size < 0) {
err = frag_size;
goto failed_read;
}
} else {
frag_blk = SQUASHFS_INVALID_BLK;
frag_size = 0;
frag_offset = 0;
}
set_nlink(inode, 1);
inode->i_size = le32_to_cpu(sqsh_ino->file_size);
inode->i_fop = &generic_ro_fops;
inode->i_mode |= S_IFREG;
inode->i_blocks = ((inode->i_size - 1) >> 9) + 1;
squashfs_i(inode)->fragment_block = frag_blk;
squashfs_i(inode)->fragment_size = frag_size;
squashfs_i(inode)->fragment_offset = frag_offset;
squashfs_i(inode)->start = le32_to_cpu(sqsh_ino->start_block);
squashfs_i(inode)->block_list_start = block;
squashfs_i(inode)->offset = offset;
inode->i_data.a_ops = &squashfs_aops;
TRACE("File inode %x:%x, start_block %llx, block_list_start "
"%llx, offset %x\n", SQUASHFS_INODE_BLK(ino),
offset, squashfs_i(inode)->start, block, offset);
break;
}
case SQUASHFS_LREG_TYPE: {
unsigned int frag_offset, frag;
int frag_size;
u64 frag_blk;
struct squashfs_lreg_inode *sqsh_ino = &squashfs_ino.lreg;
err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
sizeof(*sqsh_ino));
if (err < 0)
goto failed_read;
frag = le32_to_cpu(sqsh_ino->fragment);
if (frag != SQUASHFS_INVALID_FRAG) {
frag_offset = le32_to_cpu(sqsh_ino->offset);
frag_size = squashfs_frag_lookup(sb, frag, &frag_blk);
if (frag_size < 0) {
err = frag_size;
goto failed_read;
}
} else {
frag_blk = SQUASHFS_INVALID_BLK;
frag_size = 0;
frag_offset = 0;
}
xattr_id = le32_to_cpu(sqsh_ino->xattr);
set_nlink(inode, le32_to_cpu(sqsh_ino->nlink));
inode->i_size = le64_to_cpu(sqsh_ino->file_size);
inode->i_op = &squashfs_inode_ops;
inode->i_fop = &generic_ro_fops;
inode->i_mode |= S_IFREG;
inode->i_blocks = (inode->i_size -
le64_to_cpu(sqsh_ino->sparse) + 511) >> 9;
squashfs_i(inode)->fragment_block = frag_blk;
squashfs_i(inode)->fragment_size = frag_size;
squashfs_i(inode)->fragment_offset = frag_offset;
squashfs_i(inode)->start = le64_to_cpu(sqsh_ino->start_block);
squashfs_i(inode)->block_list_start = block;
squashfs_i(inode)->offset = offset;
inode->i_data.a_ops = &squashfs_aops;
TRACE("File inode %x:%x, start_block %llx, block_list_start "
"%llx, offset %x\n", SQUASHFS_INODE_BLK(ino),
offset, squashfs_i(inode)->start, block, offset);
break;
}
case SQUASHFS_DIR_TYPE: {
struct squashfs_dir_inode *sqsh_ino = &squashfs_ino.dir;
err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
sizeof(*sqsh_ino));
if (err < 0)
goto failed_read;
set_nlink(inode, le32_to_cpu(sqsh_ino->nlink));
inode->i_size = le16_to_cpu(sqsh_ino->file_size);
inode->i_op = &squashfs_dir_inode_ops;
inode->i_fop = &squashfs_dir_ops;
inode->i_mode |= S_IFDIR;
squashfs_i(inode)->start = le32_to_cpu(sqsh_ino->start_block);
squashfs_i(inode)->offset = le16_to_cpu(sqsh_ino->offset);
squashfs_i(inode)->dir_idx_cnt = 0;
squashfs_i(inode)->parent = le32_to_cpu(sqsh_ino->parent_inode);
TRACE("Directory inode %x:%x, start_block %llx, offset %x\n",
SQUASHFS_INODE_BLK(ino), offset,
squashfs_i(inode)->start,
le16_to_cpu(sqsh_ino->offset));
break;
}
case SQUASHFS_LDIR_TYPE: {
struct squashfs_ldir_inode *sqsh_ino = &squashfs_ino.ldir;
err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
sizeof(*sqsh_ino));
if (err < 0)
goto failed_read;
xattr_id = le32_to_cpu(sqsh_ino->xattr);
set_nlink(inode, le32_to_cpu(sqsh_ino->nlink));
inode->i_size = le32_to_cpu(sqsh_ino->file_size);
inode->i_op = &squashfs_dir_inode_ops;
inode->i_fop = &squashfs_dir_ops;
inode->i_mode |= S_IFDIR;
squashfs_i(inode)->start = le32_to_cpu(sqsh_ino->start_block);
squashfs_i(inode)->offset = le16_to_cpu(sqsh_ino->offset);
squashfs_i(inode)->dir_idx_start = block;
squashfs_i(inode)->dir_idx_offset = offset;
squashfs_i(inode)->dir_idx_cnt = le16_to_cpu(sqsh_ino->i_count);
squashfs_i(inode)->parent = le32_to_cpu(sqsh_ino->parent_inode);
TRACE("Long directory inode %x:%x, start_block %llx, offset "
"%x\n", SQUASHFS_INODE_BLK(ino), offset,
squashfs_i(inode)->start,
le16_to_cpu(sqsh_ino->offset));
break;
}
case SQUASHFS_SYMLINK_TYPE:
case SQUASHFS_LSYMLINK_TYPE: {
struct squashfs_symlink_inode *sqsh_ino = &squashfs_ino.symlink;
err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
sizeof(*sqsh_ino));
if (err < 0)
goto failed_read;
set_nlink(inode, le32_to_cpu(sqsh_ino->nlink));
inode->i_size = le32_to_cpu(sqsh_ino->symlink_size);
inode->i_op = &squashfs_symlink_inode_ops;
inode->i_data.a_ops = &squashfs_symlink_aops;
inode->i_mode |= S_IFLNK;
squashfs_i(inode)->start = block;
squashfs_i(inode)->offset = offset;
if (type == SQUASHFS_LSYMLINK_TYPE) {
__le32 xattr;
err = squashfs_read_metadata(sb, NULL, &block,
&offset, inode->i_size);
if (err < 0)
goto failed_read;
err = squashfs_read_metadata(sb, &xattr, &block,
&offset, sizeof(xattr));
if (err < 0)
goto failed_read;
xattr_id = le32_to_cpu(xattr);
}
TRACE("Symbolic link inode %x:%x, start_block %llx, offset "
"%x\n", SQUASHFS_INODE_BLK(ino), offset,
block, offset);
break;
}
case SQUASHFS_BLKDEV_TYPE:
case SQUASHFS_CHRDEV_TYPE: {
struct squashfs_dev_inode *sqsh_ino = &squashfs_ino.dev;
unsigned int rdev;
err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
sizeof(*sqsh_ino));
if (err < 0)
goto failed_read;
if (type == SQUASHFS_CHRDEV_TYPE)
inode->i_mode |= S_IFCHR;
else
inode->i_mode |= S_IFBLK;
set_nlink(inode, le32_to_cpu(sqsh_ino->nlink));
rdev = le32_to_cpu(sqsh_ino->rdev);
init_special_inode(inode, inode->i_mode, new_decode_dev(rdev));
TRACE("Device inode %x:%x, rdev %x\n",
SQUASHFS_INODE_BLK(ino), offset, rdev);
break;
}
case SQUASHFS_LBLKDEV_TYPE:
case SQUASHFS_LCHRDEV_TYPE: {
struct squashfs_ldev_inode *sqsh_ino = &squashfs_ino.ldev;
unsigned int rdev;
err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
sizeof(*sqsh_ino));
if (err < 0)
goto failed_read;
if (type == SQUASHFS_LCHRDEV_TYPE)
inode->i_mode |= S_IFCHR;
else
inode->i_mode |= S_IFBLK;
xattr_id = le32_to_cpu(sqsh_ino->xattr);
inode->i_op = &squashfs_inode_ops;
set_nlink(inode, le32_to_cpu(sqsh_ino->nlink));
rdev = le32_to_cpu(sqsh_ino->rdev);
init_special_inode(inode, inode->i_mode, new_decode_dev(rdev));
TRACE("Device inode %x:%x, rdev %x\n",
SQUASHFS_INODE_BLK(ino), offset, rdev);
break;
}
case SQUASHFS_FIFO_TYPE:
case SQUASHFS_SOCKET_TYPE: {
struct squashfs_ipc_inode *sqsh_ino = &squashfs_ino.ipc;
err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
sizeof(*sqsh_ino));
if (err < 0)
goto failed_read;
if (type == SQUASHFS_FIFO_TYPE)
inode->i_mode |= S_IFIFO;
else
inode->i_mode |= S_IFSOCK;
set_nlink(inode, le32_to_cpu(sqsh_ino->nlink));
init_special_inode(inode, inode->i_mode, 0);
break;
}
case SQUASHFS_LFIFO_TYPE:
case SQUASHFS_LSOCKET_TYPE: {
struct squashfs_lipc_inode *sqsh_ino = &squashfs_ino.lipc;
err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
sizeof(*sqsh_ino));
if (err < 0)
goto failed_read;
if (type == SQUASHFS_LFIFO_TYPE)
inode->i_mode |= S_IFIFO;
else
inode->i_mode |= S_IFSOCK;
xattr_id = le32_to_cpu(sqsh_ino->xattr);
inode->i_op = &squashfs_inode_ops;
set_nlink(inode, le32_to_cpu(sqsh_ino->nlink));
init_special_inode(inode, inode->i_mode, 0);
break;
}
default:
ERROR("Unknown inode type %d in squashfs_iget!\n", type);
return -EINVAL;
}
if (xattr_id != SQUASHFS_INVALID_XATTR && msblk->xattr_id_table) {
err = squashfs_xattr_lookup(sb, xattr_id,
&squashfs_i(inode)->xattr_count,
&squashfs_i(inode)->xattr_size,
&squashfs_i(inode)->xattr);
if (err < 0)
goto failed_read;
inode->i_blocks += ((squashfs_i(inode)->xattr_size - 1) >> 9)
+ 1;
} else
squashfs_i(inode)->xattr_count = 0;
return 0;
failed_read:
ERROR("Unable to read inode 0x%llx\n", ino);
return err;
}
const struct inode_operations squashfs_inode_ops = {
.getxattr = generic_getxattr,
.listxattr = squashfs_listxattr
};
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