// SPDX-License-Identifier: GPL-2.0-or-later
|
/*
|
* Squashfs - a compressed read only filesystem for Linux
|
*
|
* Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
|
* Phillip Lougher <phillip@squashfs.org.uk>
|
*
|
* export.c
|
*/
|
|
/*
|
* This file implements code to make Squashfs filesystems exportable (NFS etc.)
|
*
|
* The export code uses an inode lookup table to map inode numbers passed in
|
* filehandles to an inode location on disk. This table is stored compressed
|
* into metadata blocks. A second index table is used to locate these. This
|
* second index table for speed of access (and because it is small) is read at
|
* mount time and cached in memory.
|
*
|
* The inode lookup table is used only by the export code, inode disk
|
* locations are directly encoded in directories, enabling direct access
|
* without an intermediate lookup for all operations except the export ops.
|
*/
|
|
#include <linux/fs.h>
|
#include <linux/vfs.h>
|
#include <linux/dcache.h>
|
#include <linux/exportfs.h>
|
#include <linux/slab.h>
|
|
#include "squashfs_fs.h"
|
#include "squashfs_fs_sb.h"
|
#include "squashfs_fs_i.h"
|
#include "squashfs.h"
|
|
/*
|
* Look-up inode number (ino) in table, returning the inode location.
|
*/
|
static long long squashfs_inode_lookup(struct super_block *sb, int ino_num)
|
{
|
struct squashfs_sb_info *msblk = sb->s_fs_info;
|
int blk = SQUASHFS_LOOKUP_BLOCK(ino_num - 1);
|
int offset = SQUASHFS_LOOKUP_BLOCK_OFFSET(ino_num - 1);
|
u64 start;
|
__le64 ino;
|
int err;
|
|
TRACE("Entered squashfs_inode_lookup, inode_number = %d\n", ino_num);
|
|
if (ino_num == 0 || (ino_num - 1) >= msblk->inodes)
|
return -EINVAL;
|
|
start = le64_to_cpu(msblk->inode_lookup_table[blk]);
|
|
err = squashfs_read_metadata(sb, &ino, &start, &offset, sizeof(ino));
|
if (err < 0)
|
return err;
|
|
TRACE("squashfs_inode_lookup, inode = 0x%llx\n",
|
(u64) le64_to_cpu(ino));
|
|
return le64_to_cpu(ino);
|
}
|
|
|
static struct dentry *squashfs_export_iget(struct super_block *sb,
|
unsigned int ino_num)
|
{
|
long long ino;
|
struct dentry *dentry = ERR_PTR(-ENOENT);
|
|
TRACE("Entered squashfs_export_iget\n");
|
|
ino = squashfs_inode_lookup(sb, ino_num);
|
if (ino >= 0)
|
dentry = d_obtain_alias(squashfs_iget(sb, ino, ino_num));
|
|
return dentry;
|
}
|
|
|
static struct dentry *squashfs_fh_to_dentry(struct super_block *sb,
|
struct fid *fid, int fh_len, int fh_type)
|
{
|
if ((fh_type != FILEID_INO32_GEN && fh_type != FILEID_INO32_GEN_PARENT)
|
|| fh_len < 2)
|
return NULL;
|
|
return squashfs_export_iget(sb, fid->i32.ino);
|
}
|
|
|
static struct dentry *squashfs_fh_to_parent(struct super_block *sb,
|
struct fid *fid, int fh_len, int fh_type)
|
{
|
if (fh_type != FILEID_INO32_GEN_PARENT || fh_len < 4)
|
return NULL;
|
|
return squashfs_export_iget(sb, fid->i32.parent_ino);
|
}
|
|
|
static struct dentry *squashfs_get_parent(struct dentry *child)
|
{
|
struct inode *inode = d_inode(child);
|
unsigned int parent_ino = squashfs_i(inode)->parent;
|
|
return squashfs_export_iget(inode->i_sb, parent_ino);
|
}
|
|
|
/*
|
* Read uncompressed inode lookup table indexes off disk into memory
|
*/
|
__le64 *squashfs_read_inode_lookup_table(struct super_block *sb,
|
u64 lookup_table_start, u64 next_table, unsigned int inodes)
|
{
|
unsigned int length = SQUASHFS_LOOKUP_BLOCK_BYTES(inodes);
|
unsigned int indexes = SQUASHFS_LOOKUP_BLOCKS(inodes);
|
int n;
|
__le64 *table;
|
u64 start, end;
|
|
TRACE("In read_inode_lookup_table, length %d\n", length);
|
|
/* Sanity check values */
|
|
/* there should always be at least one inode */
|
if (inodes == 0)
|
return ERR_PTR(-EINVAL);
|
|
/*
|
* The computed size of the lookup table (length bytes) should exactly
|
* match the table start and end points
|
*/
|
if (length != (next_table - lookup_table_start))
|
return ERR_PTR(-EINVAL);
|
|
table = squashfs_read_table(sb, lookup_table_start, length);
|
if (IS_ERR(table))
|
return table;
|
|
/*
|
* table0], table[1], ... table[indexes - 1] store the locations
|
* of the compressed inode lookup blocks. Each entry should be
|
* less than the next (i.e. table[0] < table[1]), and the difference
|
* between them should be SQUASHFS_METADATA_SIZE or less.
|
* table[indexes - 1] should be less than lookup_table_start, and
|
* again the difference should be SQUASHFS_METADATA_SIZE or less
|
*/
|
for (n = 0; n < (indexes - 1); n++) {
|
start = le64_to_cpu(table[n]);
|
end = le64_to_cpu(table[n + 1]);
|
|
if (start >= end
|
|| (end - start) >
|
(SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) {
|
kfree(table);
|
return ERR_PTR(-EINVAL);
|
}
|
}
|
|
start = le64_to_cpu(table[indexes - 1]);
|
if (start >= lookup_table_start ||
|
(lookup_table_start - start) >
|
(SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) {
|
kfree(table);
|
return ERR_PTR(-EINVAL);
|
}
|
|
return table;
|
}
|
|
|
const struct export_operations squashfs_export_ops = {
|
.fh_to_dentry = squashfs_fh_to_dentry,
|
.fh_to_parent = squashfs_fh_to_parent,
|
.get_parent = squashfs_get_parent
|
};
|
