// 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> * * fragment.c */ /* * This file implements code to handle compressed fragments (tail-end packed * datablocks). * * Regular files contain a fragment index which is mapped to a fragment * location on disk and compressed size using a fragment lookup table. * Like everything in Squashfs this fragment lookup table is itself 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. */ #include <linux/fs.h> #include <linux/vfs.h> #include <linux/slab.h> #include "squashfs_fs.h" #include "squashfs_fs_sb.h" #include "squashfs.h" /* * Look-up fragment using the fragment index table. Return the on disk * location of the fragment and its compressed size */ int squashfs_frag_lookup(struct super_block *sb, unsigned int fragment, u64 *fragment_block) { struct squashfs_sb_info *msblk = sb->s_fs_info; int block, offset, size; struct squashfs_fragment_entry fragment_entry; u64 start_block; if (fragment >= msblk->fragments) return -EIO; block = SQUASHFS_FRAGMENT_INDEX(fragment); offset = SQUASHFS_FRAGMENT_INDEX_OFFSET(fragment); start_block = le64_to_cpu(msblk->fragment_index[block]); size = squashfs_read_metadata(sb, &fragment_entry, &start_block, &offset, sizeof(fragment_entry)); if (size < 0) return size; *fragment_block = le64_to_cpu(fragment_entry.start_block); return squashfs_block_size(fragment_entry.size); } /* * Read the uncompressed fragment lookup table indexes off disk into memory */ __le64 *squashfs_read_fragment_index_table(struct super_block *sb, u64 fragment_table_start, u64 next_table, unsigned int fragments) { unsigned int length = SQUASHFS_FRAGMENT_INDEX_BYTES(fragments); __le64 *table; /* * Sanity check, length bytes should not extend into the next table - * this check also traps instances where fragment_table_start is * incorrectly larger than the next table start */ if (fragment_table_start + length > next_table) return ERR_PTR(-EINVAL); table = squashfs_read_table(sb, fragment_table_start, length); /* * table[0] points to the first fragment table metadata block, this * should be less than fragment_table_start */ if (!IS_ERR(table) && le64_to_cpu(table[0]) >= fragment_table_start) { kfree(table); return ERR_PTR(-EINVAL); } return table; }