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![Sean Nyekjaer](/assets/img/avatar_default.png)
When mouting a squashfs image created without inode compression it fails
with: "unable to read inode lookup table"
It turns out that the BLOCK_OFFSET is missing when checking the
SQUASHFS_METADATA_SIZE agaist the actual size.
Link: https://lkml.kernel.org/r/20210226092903.1473545-1-sean@geanix.com
Fixes: eabac19e40
("squashfs: add more sanity checks in inode lookup")
Signed-off-by: Sean Nyekjaer <sean@geanix.com>
Acked-by: Phillip Lougher <phillip@squashfs.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
179 lines
4.7 KiB
C
179 lines
4.7 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Squashfs - a compressed read only filesystem for Linux
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*
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* Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
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* Phillip Lougher <phillip@squashfs.org.uk>
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*
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* export.c
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*/
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/*
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* This file implements code to make Squashfs filesystems exportable (NFS etc.)
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*
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* The export code uses an inode lookup table to map inode numbers passed in
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* filehandles to an inode location on disk. This table is stored compressed
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* into metadata blocks. A second index table is used to locate these. This
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* second index table for speed of access (and because it is small) is read at
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* mount time and cached in memory.
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*
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* The inode lookup table is used only by the export code, inode disk
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* locations are directly encoded in directories, enabling direct access
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* without an intermediate lookup for all operations except the export ops.
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*/
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#include <linux/fs.h>
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#include <linux/vfs.h>
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#include <linux/dcache.h>
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#include <linux/exportfs.h>
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#include <linux/slab.h>
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#include "squashfs_fs.h"
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#include "squashfs_fs_sb.h"
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#include "squashfs_fs_i.h"
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#include "squashfs.h"
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/*
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* Look-up inode number (ino) in table, returning the inode location.
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*/
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static long long squashfs_inode_lookup(struct super_block *sb, int ino_num)
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{
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struct squashfs_sb_info *msblk = sb->s_fs_info;
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int blk = SQUASHFS_LOOKUP_BLOCK(ino_num - 1);
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int offset = SQUASHFS_LOOKUP_BLOCK_OFFSET(ino_num - 1);
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u64 start;
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__le64 ino;
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int err;
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TRACE("Entered squashfs_inode_lookup, inode_number = %d\n", ino_num);
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if (ino_num == 0 || (ino_num - 1) >= msblk->inodes)
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return -EINVAL;
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start = le64_to_cpu(msblk->inode_lookup_table[blk]);
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err = squashfs_read_metadata(sb, &ino, &start, &offset, sizeof(ino));
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if (err < 0)
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return err;
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TRACE("squashfs_inode_lookup, inode = 0x%llx\n",
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(u64) le64_to_cpu(ino));
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return le64_to_cpu(ino);
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}
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static struct dentry *squashfs_export_iget(struct super_block *sb,
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unsigned int ino_num)
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{
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long long ino;
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struct dentry *dentry = ERR_PTR(-ENOENT);
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TRACE("Entered squashfs_export_iget\n");
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ino = squashfs_inode_lookup(sb, ino_num);
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if (ino >= 0)
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dentry = d_obtain_alias(squashfs_iget(sb, ino, ino_num));
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return dentry;
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}
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static struct dentry *squashfs_fh_to_dentry(struct super_block *sb,
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struct fid *fid, int fh_len, int fh_type)
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{
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if ((fh_type != FILEID_INO32_GEN && fh_type != FILEID_INO32_GEN_PARENT)
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|| fh_len < 2)
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return NULL;
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return squashfs_export_iget(sb, fid->i32.ino);
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}
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static struct dentry *squashfs_fh_to_parent(struct super_block *sb,
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struct fid *fid, int fh_len, int fh_type)
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{
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if (fh_type != FILEID_INO32_GEN_PARENT || fh_len < 4)
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return NULL;
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return squashfs_export_iget(sb, fid->i32.parent_ino);
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}
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static struct dentry *squashfs_get_parent(struct dentry *child)
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{
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struct inode *inode = d_inode(child);
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unsigned int parent_ino = squashfs_i(inode)->parent;
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return squashfs_export_iget(inode->i_sb, parent_ino);
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}
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/*
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* Read uncompressed inode lookup table indexes off disk into memory
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*/
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__le64 *squashfs_read_inode_lookup_table(struct super_block *sb,
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u64 lookup_table_start, u64 next_table, unsigned int inodes)
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{
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unsigned int length = SQUASHFS_LOOKUP_BLOCK_BYTES(inodes);
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unsigned int indexes = SQUASHFS_LOOKUP_BLOCKS(inodes);
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int n;
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__le64 *table;
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u64 start, end;
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TRACE("In read_inode_lookup_table, length %d\n", length);
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/* Sanity check values */
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/* there should always be at least one inode */
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if (inodes == 0)
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return ERR_PTR(-EINVAL);
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/*
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* The computed size of the lookup table (length bytes) should exactly
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* match the table start and end points
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*/
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if (length != (next_table - lookup_table_start))
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return ERR_PTR(-EINVAL);
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table = squashfs_read_table(sb, lookup_table_start, length);
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if (IS_ERR(table))
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return table;
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/*
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* table0], table[1], ... table[indexes - 1] store the locations
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* of the compressed inode lookup blocks. Each entry should be
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* less than the next (i.e. table[0] < table[1]), and the difference
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* between them should be SQUASHFS_METADATA_SIZE or less.
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* table[indexes - 1] should be less than lookup_table_start, and
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* again the difference should be SQUASHFS_METADATA_SIZE or less
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*/
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for (n = 0; n < (indexes - 1); n++) {
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start = le64_to_cpu(table[n]);
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end = le64_to_cpu(table[n + 1]);
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if (start >= end
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|| (end - start) >
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(SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) {
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kfree(table);
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return ERR_PTR(-EINVAL);
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}
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}
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start = le64_to_cpu(table[indexes - 1]);
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if (start >= lookup_table_start ||
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(lookup_table_start - start) >
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(SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) {
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kfree(table);
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return ERR_PTR(-EINVAL);
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}
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return table;
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}
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const struct export_operations squashfs_export_ops = {
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.fh_to_dentry = squashfs_fh_to_dentry,
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.fh_to_parent = squashfs_fh_to_parent,
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.get_parent = squashfs_get_parent
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};
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