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411 lines
11 KiB
C
411 lines
11 KiB
C
/*
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* Unsquash a squashfs filesystem. This is a highly compressed read only
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* filesystem.
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*
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* Copyright (c) 2009, 2010, 2011, 2012, 2019
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* Phillip Lougher <phillip@squashfs.org.uk>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2,
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* or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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* unsquash-1.c
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*/
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#include "unsquashfs.h"
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#include "squashfs_compat.h"
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static unsigned int *uid_table, *guid_table;
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static char *inode_table, *directory_table;
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static squashfs_operations ops;
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static void read_block_list(unsigned int *block_list, char *block_ptr, int blocks)
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{
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unsigned short block_size;
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int i;
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TRACE("read_block_list: blocks %d\n", blocks);
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for(i = 0; i < blocks; i++, block_ptr += 2) {
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if(swap) {
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unsigned short sblock_size;
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memcpy(&sblock_size, block_ptr, sizeof(unsigned short));
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SQUASHFS_SWAP_SHORTS_3((&block_size), &sblock_size, 1);
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} else
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memcpy(&block_size, block_ptr, sizeof(unsigned short));
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block_list[i] = SQUASHFS_COMPRESSED_SIZE(block_size) |
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(SQUASHFS_COMPRESSED(block_size) ? 0 :
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SQUASHFS_COMPRESSED_BIT_BLOCK);
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}
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}
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static struct inode *read_inode(unsigned int start_block, unsigned int offset)
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{
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static union squashfs_inode_header_1 header;
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long long start = sBlk.s.inode_table_start + start_block;
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int bytes = lookup_entry(inode_table_hash, start);
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char *block_ptr = inode_table + bytes + offset;
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static struct inode i;
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TRACE("read_inode: reading inode [%d:%d]\n", start_block, offset);
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if(bytes == -1)
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EXIT_UNSQUASH("read_inode: inode table block %lld not found\n",
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start);
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if(swap) {
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squashfs_base_inode_header_1 sinode;
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memcpy(&sinode, block_ptr, sizeof(header.base));
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SQUASHFS_SWAP_BASE_INODE_HEADER_1(&header.base, &sinode,
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sizeof(squashfs_base_inode_header_1));
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} else
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memcpy(&header.base, block_ptr, sizeof(header.base));
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i.uid = (uid_t) uid_table[(header.base.inode_type - 1) /
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SQUASHFS_TYPES * 16 + header.base.uid];
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if(header.base.inode_type == SQUASHFS_IPC_TYPE) {
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squashfs_ipc_inode_header_1 *inodep = &header.ipc;
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if(swap) {
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squashfs_ipc_inode_header_1 sinodep;
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memcpy(&sinodep, block_ptr, sizeof(sinodep));
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SQUASHFS_SWAP_IPC_INODE_HEADER_1(inodep, &sinodep);
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} else
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memcpy(inodep, block_ptr, sizeof(*inodep));
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if(inodep->type == SQUASHFS_SOCKET_TYPE) {
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i.mode = S_IFSOCK | header.base.mode;
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i.type = SQUASHFS_SOCKET_TYPE;
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} else {
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i.mode = S_IFIFO | header.base.mode;
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i.type = SQUASHFS_FIFO_TYPE;
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}
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i.uid = (uid_t) uid_table[inodep->offset * 16 + inodep->uid];
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} else {
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i.mode = lookup_type[(header.base.inode_type - 1) %
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SQUASHFS_TYPES + 1] | header.base.mode;
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i.type = (header.base.inode_type - 1) % SQUASHFS_TYPES + 1;
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}
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i.xattr = SQUASHFS_INVALID_XATTR;
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i.gid = header.base.guid == 15 ? i.uid :
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(uid_t) guid_table[header.base.guid];
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i.time = sBlk.s.mkfs_time;
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i.inode_number = inode_number ++;
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switch(i.type) {
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case SQUASHFS_DIR_TYPE: {
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squashfs_dir_inode_header_1 *inode = &header.dir;
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if(swap) {
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squashfs_dir_inode_header_1 sinode;
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memcpy(&sinode, block_ptr, sizeof(header.dir));
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SQUASHFS_SWAP_DIR_INODE_HEADER_1(inode,
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&sinode);
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} else
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memcpy(inode, block_ptr, sizeof(header.dir));
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i.data = inode->file_size;
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i.offset = inode->offset;
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i.start = inode->start_block;
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i.time = inode->mtime;
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break;
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}
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case SQUASHFS_FILE_TYPE: {
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squashfs_reg_inode_header_1 *inode = &header.reg;
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if(swap) {
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squashfs_reg_inode_header_1 sinode;
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memcpy(&sinode, block_ptr, sizeof(sinode));
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SQUASHFS_SWAP_REG_INODE_HEADER_1(inode,
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&sinode);
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} else
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memcpy(inode, block_ptr, sizeof(*inode));
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i.data = inode->file_size;
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i.time = inode->mtime;
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i.blocks = (i.data + sBlk.s.block_size - 1) >>
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sBlk.s.block_log;
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i.start = inode->start_block;
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i.block_ptr = block_ptr + sizeof(*inode);
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i.fragment = 0;
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i.frag_bytes = 0;
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i.offset = 0;
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i.sparse = 0;
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break;
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}
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case SQUASHFS_SYMLINK_TYPE: {
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squashfs_symlink_inode_header_1 *inodep =
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&header.symlink;
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if(swap) {
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squashfs_symlink_inode_header_1 sinodep;
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memcpy(&sinodep, block_ptr, sizeof(sinodep));
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SQUASHFS_SWAP_SYMLINK_INODE_HEADER_1(inodep,
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&sinodep);
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} else
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memcpy(inodep, block_ptr, sizeof(*inodep));
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i.symlink = malloc(inodep->symlink_size + 1);
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if(i.symlink == NULL)
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EXIT_UNSQUASH("read_inode: failed to malloc "
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"symlink data\n");
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strncpy(i.symlink, block_ptr +
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sizeof(squashfs_symlink_inode_header_1),
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inodep->symlink_size);
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i.symlink[inodep->symlink_size] = '\0';
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i.data = inodep->symlink_size;
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break;
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}
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case SQUASHFS_BLKDEV_TYPE:
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case SQUASHFS_CHRDEV_TYPE: {
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squashfs_dev_inode_header_1 *inodep = &header.dev;
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if(swap) {
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squashfs_dev_inode_header_1 sinodep;
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memcpy(&sinodep, block_ptr, sizeof(sinodep));
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SQUASHFS_SWAP_DEV_INODE_HEADER_1(inodep,
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&sinodep);
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} else
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memcpy(inodep, block_ptr, sizeof(*inodep));
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i.data = inodep->rdev;
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break;
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}
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case SQUASHFS_FIFO_TYPE:
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case SQUASHFS_SOCKET_TYPE: {
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i.data = 0;
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break;
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}
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default:
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EXIT_UNSQUASH("Unknown inode type %d in "
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" read_inode_header_1!\n",
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header.base.inode_type);
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}
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return &i;
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}
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static struct dir *squashfs_opendir(unsigned int block_start, unsigned int offset,
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struct inode **i)
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{
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squashfs_dir_header_2 dirh;
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char buffer[sizeof(squashfs_dir_entry_2) + SQUASHFS_NAME_LEN + 1]
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__attribute__((aligned));
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squashfs_dir_entry_2 *dire = (squashfs_dir_entry_2 *) buffer;
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long long start;
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int bytes;
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int dir_count, size;
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struct dir_ent *new_dir;
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struct dir *dir;
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TRACE("squashfs_opendir: inode start block %d, offset %d\n",
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block_start, offset);
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*i = read_inode(block_start, offset);
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dir = malloc(sizeof(struct dir));
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if(dir == NULL)
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EXIT_UNSQUASH("squashfs_opendir: malloc failed!\n");
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dir->dir_count = 0;
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dir->cur_entry = 0;
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dir->mode = (*i)->mode;
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dir->uid = (*i)->uid;
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dir->guid = (*i)->gid;
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dir->mtime = (*i)->time;
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dir->xattr = (*i)->xattr;
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dir->dirs = NULL;
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if ((*i)->data == 0)
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/*
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* if the directory is empty, skip the unnecessary
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* lookup_entry, this fixes the corner case with
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* completely empty filesystems where lookup_entry correctly
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* returning -1 is incorrectly treated as an error
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*/
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return dir;
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start = sBlk.s.directory_table_start + (*i)->start;
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bytes = lookup_entry(directory_table_hash, start);
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if(bytes == -1)
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EXIT_UNSQUASH("squashfs_opendir: directory block %d not "
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"found!\n", block_start);
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bytes += (*i)->offset;
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size = (*i)->data + bytes;
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while(bytes < size) {
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if(swap) {
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squashfs_dir_header_2 sdirh;
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memcpy(&sdirh, directory_table + bytes, sizeof(sdirh));
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SQUASHFS_SWAP_DIR_HEADER_2(&dirh, &sdirh);
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} else
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memcpy(&dirh, directory_table + bytes, sizeof(dirh));
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dir_count = dirh.count + 1;
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TRACE("squashfs_opendir: Read directory header @ byte position "
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"%d, %d directory entries\n", bytes, dir_count);
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bytes += sizeof(dirh);
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/* dir_count should never be larger than SQUASHFS_DIR_COUNT */
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if(dir_count > SQUASHFS_DIR_COUNT) {
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ERROR("File system corrupted: too many entries in directory\n");
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goto corrupted;
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}
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while(dir_count--) {
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if(swap) {
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squashfs_dir_entry_2 sdire;
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memcpy(&sdire, directory_table + bytes,
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sizeof(sdire));
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SQUASHFS_SWAP_DIR_ENTRY_2(dire, &sdire);
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} else
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memcpy(dire, directory_table + bytes,
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sizeof(*dire));
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bytes += sizeof(*dire);
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/* size should never be SQUASHFS_NAME_LEN or larger */
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if(dire->size >= SQUASHFS_NAME_LEN) {
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ERROR("File system corrupted: filename too long\n");
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goto corrupted;
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}
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memcpy(dire->name, directory_table + bytes,
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dire->size + 1);
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dire->name[dire->size + 1] = '\0';
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TRACE("squashfs_opendir: directory entry %s, inode "
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"%d:%d, type %d\n", dire->name,
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dirh.start_block, dire->offset, dire->type);
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if((dir->dir_count % DIR_ENT_SIZE) == 0) {
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new_dir = realloc(dir->dirs, (dir->dir_count +
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DIR_ENT_SIZE) * sizeof(struct dir_ent));
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if(new_dir == NULL)
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EXIT_UNSQUASH("squashfs_opendir: "
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"realloc failed!\n");
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dir->dirs = new_dir;
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}
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strcpy(dir->dirs[dir->dir_count].name, dire->name);
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dir->dirs[dir->dir_count].start_block =
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dirh.start_block;
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dir->dirs[dir->dir_count].offset = dire->offset;
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dir->dirs[dir->dir_count].type = dire->type;
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dir->dir_count ++;
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bytes += dire->size + 1;
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}
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}
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return dir;
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corrupted:
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free(dir->dirs);
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free(dir);
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return NULL;
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}
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squashfs_operations *read_filesystem_tables_1()
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{
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long long table_start;
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/* Read uid and gid lookup tables */
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/* Sanity check super block contents */
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if(sBlk.no_guids) {
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if(sBlk.guid_start >= sBlk.s.bytes_used) {
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ERROR("read_filesystem_tables: gid start too large in super block\n");
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goto corrupted;
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}
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/* In 1.x filesystems, there should never be more than 15 gids */
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if(sBlk.no_guids > 15) {
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ERROR("read_filesystem_tables: gids too large in super block\n");
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goto corrupted;
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}
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if(read_ids(sBlk.no_guids, sBlk.guid_start, sBlk.s.bytes_used, &guid_table) == FALSE)
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goto corrupted;
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table_start = sBlk.guid_start;
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} else {
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/* no guids, guid_start should be 0 */
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if(sBlk.guid_start != 0) {
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ERROR("read_filesystem_tables: gid start too large in super block\n");
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goto corrupted;
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}
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table_start = sBlk.s.bytes_used;
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}
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if(sBlk.uid_start >= table_start) {
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ERROR("read_filesystem_tables: uid start too large in super block\n");
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goto corrupted;
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}
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/* There should be at least one uid */
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if(sBlk.no_uids == 0) {
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ERROR("read_filesystem_tables: uid count bad in super block\n");
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goto corrupted;
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}
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/* In 1.x filesystems, there should never be more than 48 uids */
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if(sBlk.no_uids > 48) {
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ERROR("read_filesystem_tables: uids too large in super block\n");
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goto corrupted;
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}
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if(read_ids(sBlk.no_uids, sBlk.uid_start, table_start, &uid_table) == FALSE)
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goto corrupted;
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table_start = sBlk.uid_start;
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/* Read directory table */
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/* Sanity check super block contents */
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if(sBlk.s.directory_table_start > table_start) {
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ERROR("read_filesystem_tables: directory table start too large in super block\n");
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goto corrupted;
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}
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directory_table = read_directory_table(sBlk.s.directory_table_start,
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table_start);
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if(directory_table == NULL)
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goto corrupted;
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/* Read inode table */
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/* Sanity check super block contents */
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if(sBlk.s.inode_table_start >= sBlk.s.directory_table_start) {
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ERROR("read_filesystem_tables: inode table start too large in super block\n");
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goto corrupted;
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}
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inode_table = read_inode_table(sBlk.s.inode_table_start,
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sBlk.s.directory_table_start);
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if(inode_table == NULL)
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goto corrupted;
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return &ops;
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corrupted:
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ERROR("File system corruption detected\n");
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return NULL;
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}
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static squashfs_operations ops = {
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.opendir = squashfs_opendir,
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.read_block_list = read_block_list,
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.read_inode = read_inode
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};
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