| #!/usr/bin/env python3 |
| # |
| # Copyright 2018, The Android Open Source Project |
| # |
| # Licensed under the Apache License, Version 2.0 (the "License"); |
| # you may not use this file except in compliance with the License. |
| # You may obtain a copy of the License at |
| # |
| # http://www.apache.org/licenses/LICENSE-2.0 |
| # |
| # Unless required by applicable law or agreed to in writing, software |
| # distributed under the License is distributed on an "AS IS" BASIS, |
| # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| # See the License for the specific language governing permissions and |
| # limitations under the License. |
| |
| """Unpacks the boot image. |
| |
| Extracts the kernel, ramdisk, second bootloader, dtb and recovery dtbo images. |
| """ |
| |
| from argparse import ArgumentParser, FileType, RawDescriptionHelpFormatter |
| from struct import unpack |
| import os |
| import shlex |
| |
| BOOT_IMAGE_HEADER_V3_PAGESIZE = 4096 |
| VENDOR_RAMDISK_NAME_SIZE = 32 |
| VENDOR_RAMDISK_TABLE_ENTRY_BOARD_ID_SIZE = 16 |
| |
| |
| def create_out_dir(dir_path): |
| """creates a directory 'dir_path' if it does not exist""" |
| if not os.path.exists(dir_path): |
| os.makedirs(dir_path) |
| |
| |
| def extract_image(offset, size, bootimage, extracted_image_name): |
| """extracts an image from the bootimage""" |
| bootimage.seek(offset) |
| with open(extracted_image_name, 'wb') as file_out: |
| file_out.write(bootimage.read(size)) |
| |
| |
| def get_number_of_pages(image_size, page_size): |
| """calculates the number of pages required for the image""" |
| return (image_size + page_size - 1) // page_size |
| |
| |
| def cstr(s): |
| """Remove first NULL character and any character beyond.""" |
| return s.split('\0', 1)[0] |
| |
| |
| def format_os_version(os_version): |
| if os_version == 0: |
| return None |
| a = os_version >> 14 |
| b = os_version >> 7 & ((1<<7) - 1) |
| c = os_version & ((1<<7) - 1) |
| return '{}.{}.{}'.format(a, b, c) |
| |
| |
| def format_os_patch_level(os_patch_level): |
| if os_patch_level == 0: |
| return None |
| y = os_patch_level >> 4 |
| y += 2000 |
| m = os_patch_level & ((1<<4) - 1) |
| return '{:04d}-{:02d}'.format(y, m) |
| |
| |
| def decode_os_version_patch_level(os_version_patch_level): |
| """Returns a tuple of (os_version, os_patch_level).""" |
| os_version = os_version_patch_level >> 11 |
| os_patch_level = os_version_patch_level & ((1<<11) - 1) |
| return (format_os_version(os_version), |
| format_os_patch_level(os_patch_level)) |
| |
| |
| class BootImageInfoFormatter: |
| """Formats the boot image info.""" |
| |
| def format_pretty_text(self): |
| lines = [] |
| lines.append(f'boot magic: {self.boot_magic}') |
| |
| if self.header_version < 3: |
| lines.append(f'kernel_size: {self.kernel_size}') |
| lines.append( |
| f'kernel load address: {self.kernel_load_address:#010x}') |
| lines.append(f'ramdisk size: {self.ramdisk_size}') |
| lines.append( |
| f'ramdisk load address: {self.ramdisk_load_address:#010x}') |
| lines.append(f'second bootloader size: {self.second_size}') |
| lines.append( |
| f'second bootloader load address: ' |
| f'{self.second_load_address:#010x}') |
| lines.append( |
| f'kernel tags load address: {self.tags_load_address:#010x}') |
| lines.append(f'page size: {self.page_size}') |
| else: |
| lines.append(f'kernel_size: {self.kernel_size}') |
| lines.append(f'ramdisk size: {self.ramdisk_size}') |
| |
| lines.append(f'os version: {self.os_version}') |
| lines.append(f'os patch level: {self.os_patch_level}') |
| lines.append(f'boot image header version: {self.header_version}') |
| |
| if self.header_version < 3: |
| lines.append(f'product name: {self.product_name}') |
| |
| lines.append(f'command line args: {self.cmdline}') |
| |
| if self.header_version < 3: |
| lines.append(f'additional command line args: {self.extra_cmdline}') |
| |
| if self.header_version in {1, 2}: |
| lines.append(f'recovery dtbo size: {self.recovery_dtbo_size}') |
| lines.append( |
| f'recovery dtbo offset: {self.recovery_dtbo_offset:#018x}') |
| lines.append(f'boot header size: {self.boot_header_size}') |
| |
| if self.header_version == 2: |
| lines.append(f'dtb size: {self.dtb_size}') |
| lines.append(f'dtb address: {self.dtb_load_address:#018x}') |
| |
| if self.header_version >= 4: |
| lines.append( |
| f'boot.img signature size: {self.boot_signature_size}') |
| |
| return '\n'.join(lines) |
| |
| def format_mkbootimg_argument(self): |
| args = [] |
| args.extend(['--header_version', str(self.header_version)]) |
| if self.os_version: |
| args.extend(['--os_version', self.os_version]) |
| if self.os_patch_level: |
| args.extend(['--os_patch_level', self.os_patch_level]) |
| |
| args.extend(['--kernel', os.path.join(self.image_dir, 'kernel')]) |
| args.extend(['--ramdisk', os.path.join(self.image_dir, 'ramdisk')]) |
| |
| if self.header_version >= 4 and self.boot_signature_size > 0: |
| args.extend(['--boot_signature', |
| os.path.join(self.image_dir, 'boot_signature')]) |
| |
| if self.header_version <= 2: |
| if self.second_size > 0: |
| args.extend(['--second', |
| os.path.join(self.image_dir, 'second')]) |
| if self.recovery_dtbo_size > 0: |
| args.extend(['--recovery_dtbo', |
| os.path.join(self.image_dir, 'recovery_dtbo')]) |
| if self.dtb_size > 0: |
| args.extend(['--dtb', os.path.join(self.image_dir, 'dtb')]) |
| |
| args.extend(['--pagesize', f'{self.page_size:#010x}']) |
| |
| # Kernel load address is base + kernel_offset in mkbootimg.py. |
| # However we don't know the value of 'base' when unpacking a boot |
| # image in this script, so we set 'base' to zero and 'kernel_offset' |
| # to the kernel load address, 'ramdisk_offset' to the ramdisk load |
| # address, ... etc. |
| args.extend(['--base', f'{0:#010x}']) |
| args.extend(['--kernel_offset', |
| f'{self.kernel_load_address:#010x}']) |
| args.extend(['--ramdisk_offset', |
| f'{self.ramdisk_load_address:#010x}']) |
| args.extend(['--second_offset', |
| f'{self.second_load_address:#010x}']) |
| args.extend(['--tags_offset', f'{self.tags_load_address:#010x}']) |
| |
| # dtb is added in boot image v2, and is absent in v1 or v0. |
| if self.header_version == 2: |
| # dtb_offset is uint64_t. |
| args.extend(['--dtb_offset', f'{self.dtb_load_address:#018x}']) |
| |
| args.extend(['--board', self.product_name]) |
| args.extend(['--cmdline', self.cmdline + self.extra_cmdline]) |
| else: |
| args.extend(['--cmdline', self.cmdline]) |
| |
| return args |
| |
| |
| def unpack_boot_image(args): |
| """extracts kernel, ramdisk, second bootloader and recovery dtbo""" |
| info = BootImageInfoFormatter() |
| info.boot_magic = unpack('8s', args.boot_img.read(8))[0].decode() |
| |
| kernel_ramdisk_second_info = unpack('9I', args.boot_img.read(9 * 4)) |
| # header_version is always at [8] regardless of the value of header_version. |
| info.header_version = kernel_ramdisk_second_info[8] |
| |
| if info.header_version < 3: |
| info.kernel_size = kernel_ramdisk_second_info[0] |
| info.kernel_load_address = kernel_ramdisk_second_info[1] |
| info.ramdisk_size = kernel_ramdisk_second_info[2] |
| info.ramdisk_load_address = kernel_ramdisk_second_info[3] |
| info.second_size = kernel_ramdisk_second_info[4] |
| info.second_load_address = kernel_ramdisk_second_info[5] |
| info.tags_load_address = kernel_ramdisk_second_info[6] |
| info.page_size = kernel_ramdisk_second_info[7] |
| os_version_patch_level = unpack('I', args.boot_img.read(1 * 4))[0] |
| else: |
| info.kernel_size = kernel_ramdisk_second_info[0] |
| info.ramdisk_size = kernel_ramdisk_second_info[1] |
| os_version_patch_level = kernel_ramdisk_second_info[2] |
| info.second_size = 0 |
| info.page_size = BOOT_IMAGE_HEADER_V3_PAGESIZE |
| |
| info.os_version, info.os_patch_level = decode_os_version_patch_level( |
| os_version_patch_level) |
| |
| if info.header_version < 3: |
| info.product_name = cstr(unpack('16s', |
| args.boot_img.read(16))[0].decode()) |
| info.cmdline = cstr(unpack('512s', args.boot_img.read(512))[0].decode()) |
| args.boot_img.read(32) # ignore SHA |
| info.extra_cmdline = cstr(unpack('1024s', |
| args.boot_img.read(1024))[0].decode()) |
| else: |
| info.cmdline = cstr(unpack('1536s', |
| args.boot_img.read(1536))[0].decode()) |
| |
| if info.header_version in {1, 2}: |
| info.recovery_dtbo_size = unpack('I', args.boot_img.read(1 * 4))[0] |
| info.recovery_dtbo_offset = unpack('Q', args.boot_img.read(8))[0] |
| info.boot_header_size = unpack('I', args.boot_img.read(4))[0] |
| else: |
| info.recovery_dtbo_size = 0 |
| |
| if info.header_version == 2: |
| info.dtb_size = unpack('I', args.boot_img.read(4))[0] |
| info.dtb_load_address = unpack('Q', args.boot_img.read(8))[0] |
| else: |
| info.dtb_size = 0 |
| info.dtb_load_address = 0 |
| |
| if info.header_version >= 4: |
| info.boot_signature_size = unpack('I', args.boot_img.read(4))[0] |
| else: |
| info.boot_signature_size = 0 |
| |
| # The first page contains the boot header |
| num_header_pages = 1 |
| |
| # Convenient shorthand. |
| page_size = info.page_size |
| |
| num_kernel_pages = get_number_of_pages(info.kernel_size, page_size) |
| kernel_offset = page_size * num_header_pages # header occupies a page |
| image_info_list = [(kernel_offset, info.kernel_size, 'kernel')] |
| |
| num_ramdisk_pages = get_number_of_pages(info.ramdisk_size, page_size) |
| ramdisk_offset = page_size * (num_header_pages + num_kernel_pages |
| ) # header + kernel |
| image_info_list.append((ramdisk_offset, info.ramdisk_size, 'ramdisk')) |
| |
| if info.second_size > 0: |
| second_offset = page_size * ( |
| num_header_pages + num_kernel_pages + num_ramdisk_pages |
| ) # header + kernel + ramdisk |
| image_info_list.append((second_offset, info.second_size, 'second')) |
| |
| if info.recovery_dtbo_size > 0: |
| image_info_list.append((info.recovery_dtbo_offset, |
| info.recovery_dtbo_size, |
| 'recovery_dtbo')) |
| if info.dtb_size > 0: |
| num_second_pages = get_number_of_pages(info.second_size, page_size) |
| num_recovery_dtbo_pages = get_number_of_pages( |
| info.recovery_dtbo_size, page_size) |
| dtb_offset = page_size * ( |
| num_header_pages + num_kernel_pages + num_ramdisk_pages + |
| num_second_pages + num_recovery_dtbo_pages) |
| |
| image_info_list.append((dtb_offset, info.dtb_size, 'dtb')) |
| |
| if info.boot_signature_size > 0: |
| # boot signature only exists in boot.img version >= v4. |
| # There are only kernel and ramdisk pages before the signature. |
| boot_signature_offset = page_size * ( |
| num_header_pages + num_kernel_pages + num_ramdisk_pages) |
| |
| image_info_list.append((boot_signature_offset, info.boot_signature_size, |
| 'boot_signature')) |
| |
| create_out_dir(args.out) |
| for offset, size, name in image_info_list: |
| extract_image(offset, size, args.boot_img, os.path.join(args.out, name)) |
| info.image_dir = args.out |
| |
| return info |
| |
| |
| class VendorBootImageInfoFormatter: |
| """Formats the vendor_boot image info.""" |
| |
| def format_pretty_text(self): |
| lines = [] |
| lines.append(f'boot magic: {self.boot_magic}') |
| lines.append(f'vendor boot image header version: {self.header_version}') |
| lines.append(f'page size: {self.page_size:#010x}') |
| lines.append(f'kernel load address: {self.kernel_load_address:#010x}') |
| lines.append(f'ramdisk load address: {self.ramdisk_load_address:#010x}') |
| if self.header_version > 3: |
| lines.append( |
| f'vendor ramdisk total size: {self.vendor_ramdisk_size}') |
| else: |
| lines.append(f'vendor ramdisk size: {self.vendor_ramdisk_size}') |
| lines.append(f'vendor command line args: {self.cmdline}') |
| lines.append( |
| f'kernel tags load address: {self.tags_load_address:#010x}') |
| lines.append(f'product name: {self.product_name}') |
| lines.append(f'vendor boot image header size: {self.header_size}') |
| lines.append(f'dtb size: {self.dtb_size}') |
| lines.append(f'dtb address: {self.dtb_load_address:#018x}') |
| if self.header_version > 3: |
| lines.append( |
| f'vendor ramdisk table size: {self.vendor_ramdisk_table_size}') |
| lines.append('vendor ramdisk table: [') |
| indent = lambda level: ' ' * 4 * level |
| for entry in self.vendor_ramdisk_table: |
| (output_ramdisk_name, ramdisk_size, ramdisk_offset, |
| ramdisk_type, ramdisk_name, board_id) = entry |
| lines.append(indent(1) + f'{output_ramdisk_name}: ''{') |
| lines.append(indent(2) + f'size: {ramdisk_size}') |
| lines.append(indent(2) + f'offset: {ramdisk_offset}') |
| lines.append(indent(2) + f'type: {ramdisk_type:#x}') |
| lines.append(indent(2) + f'name: {ramdisk_name}') |
| lines.append(indent(2) + 'board_id: [') |
| stride = 4 |
| for row_idx in range(0, len(board_id), stride): |
| row = board_id[row_idx:row_idx + stride] |
| lines.append( |
| indent(3) + ' '.join(f'{e:#010x},' for e in row)) |
| lines.append(indent(2) + ']') |
| lines.append(indent(1) + '}') |
| lines.append(']') |
| lines.append( |
| f'vendor bootconfig size: {self.vendor_bootconfig_size}') |
| |
| return '\n'.join(lines) |
| |
| def format_mkbootimg_argument(self): |
| args = [] |
| args.extend(['--header_version', str(self.header_version)]) |
| args.extend(['--pagesize', f'{self.page_size:#010x}']) |
| args.extend(['--base', f'{0:#010x}']) |
| args.extend(['--kernel_offset', f'{self.kernel_load_address:#010x}']) |
| args.extend(['--ramdisk_offset', f'{self.ramdisk_load_address:#010x}']) |
| args.extend(['--tags_offset', f'{self.tags_load_address:#010x}']) |
| args.extend(['--dtb_offset', f'{self.dtb_load_address:#018x}']) |
| args.extend(['--vendor_cmdline', self.cmdline]) |
| args.extend(['--board', self.product_name]) |
| |
| args.extend(['--dtb', os.path.join(self.image_dir, 'dtb')]) |
| |
| if self.header_version > 3: |
| args.extend(['--vendor_bootconfig', |
| os.path.join(self.image_dir, 'bootconfig')]) |
| |
| for entry in self.vendor_ramdisk_table: |
| (output_ramdisk_name, _, _, ramdisk_type, |
| ramdisk_name, board_id) = entry |
| args.extend(['--ramdisk_type', str(ramdisk_type)]) |
| args.extend(['--ramdisk_name', ramdisk_name]) |
| for idx, e in enumerate(board_id): |
| if e: |
| args.extend([f'--board_id{idx}', f'{e:#010x}']) |
| vendor_ramdisk_path = os.path.join( |
| self.image_dir, output_ramdisk_name) |
| args.extend(['--vendor_ramdisk_fragment', vendor_ramdisk_path]) |
| else: |
| args.extend(['--vendor_ramdisk', |
| os.path.join(self.image_dir, 'vendor_ramdisk')]) |
| |
| return args |
| |
| |
| def unpack_vendor_boot_image(args): |
| info = VendorBootImageInfoFormatter() |
| info.boot_magic = unpack('8s', args.boot_img.read(8))[0].decode() |
| info.header_version = unpack('I', args.boot_img.read(4))[0] |
| info.page_size = unpack('I', args.boot_img.read(4))[0] |
| info.kernel_load_address = unpack('I', args.boot_img.read(4))[0] |
| info.ramdisk_load_address = unpack('I', args.boot_img.read(4))[0] |
| info.vendor_ramdisk_size = unpack('I', args.boot_img.read(4))[0] |
| info.cmdline = cstr(unpack('2048s', args.boot_img.read(2048))[0].decode()) |
| info.tags_load_address = unpack('I', args.boot_img.read(4))[0] |
| info.product_name = cstr(unpack('16s', args.boot_img.read(16))[0].decode()) |
| info.header_size = unpack('I', args.boot_img.read(4))[0] |
| info.dtb_size = unpack('I', args.boot_img.read(4))[0] |
| info.dtb_load_address = unpack('Q', args.boot_img.read(8))[0] |
| |
| # Convenient shorthand. |
| page_size = info.page_size |
| # The first pages contain the boot header |
| num_boot_header_pages = get_number_of_pages(info.header_size, page_size) |
| num_boot_ramdisk_pages = get_number_of_pages( |
| info.vendor_ramdisk_size, page_size) |
| num_boot_dtb_pages = get_number_of_pages(info.dtb_size, page_size) |
| |
| ramdisk_offset_base = page_size * num_boot_header_pages |
| image_info_list = [] |
| |
| image_info_list.append( |
| (ramdisk_offset_base, info.vendor_ramdisk_size, 'vendor_ramdisk')) |
| |
| if info.header_version > 3: |
| info.vendor_ramdisk_table_size = unpack('I', args.boot_img.read(4))[0] |
| vendor_ramdisk_table_entry_num = unpack('I', args.boot_img.read(4))[0] |
| vendor_ramdisk_table_entry_size = unpack('I', args.boot_img.read(4))[0] |
| info.vendor_bootconfig_size = unpack('I', args.boot_img.read(4))[0] |
| num_vendor_ramdisk_table_pages = get_number_of_pages( |
| info.vendor_ramdisk_table_size, page_size) |
| vendor_ramdisk_table_offset = page_size * ( |
| num_boot_header_pages + num_boot_ramdisk_pages + num_boot_dtb_pages) |
| |
| vendor_ramdisk_table = [] |
| vendor_ramdisk_symlinks = [] |
| for idx in range(vendor_ramdisk_table_entry_num): |
| entry_offset = vendor_ramdisk_table_offset + ( |
| vendor_ramdisk_table_entry_size * idx) |
| args.boot_img.seek(entry_offset) |
| ramdisk_size = unpack('I', args.boot_img.read(4))[0] |
| ramdisk_offset = unpack('I', args.boot_img.read(4))[0] |
| ramdisk_type = unpack('I', args.boot_img.read(4))[0] |
| ramdisk_name = cstr(unpack( |
| f'{VENDOR_RAMDISK_NAME_SIZE}s', |
| args.boot_img.read(VENDOR_RAMDISK_NAME_SIZE))[0].decode()) |
| board_id = unpack( |
| f'{VENDOR_RAMDISK_TABLE_ENTRY_BOARD_ID_SIZE}I', |
| args.boot_img.read( |
| 4 * VENDOR_RAMDISK_TABLE_ENTRY_BOARD_ID_SIZE)) |
| output_ramdisk_name = f'vendor_ramdisk{idx:02}' |
| |
| image_info_list.append((ramdisk_offset_base + ramdisk_offset, |
| ramdisk_size, output_ramdisk_name)) |
| vendor_ramdisk_symlinks.append((output_ramdisk_name, ramdisk_name)) |
| vendor_ramdisk_table.append( |
| (output_ramdisk_name, ramdisk_size, ramdisk_offset, |
| ramdisk_type, ramdisk_name, board_id)) |
| |
| info.vendor_ramdisk_table = vendor_ramdisk_table |
| |
| bootconfig_offset = page_size * (num_boot_header_pages |
| + num_boot_ramdisk_pages + num_boot_dtb_pages |
| + num_vendor_ramdisk_table_pages) |
| image_info_list.append((bootconfig_offset, info.vendor_bootconfig_size, |
| 'bootconfig')) |
| |
| dtb_offset = page_size * (num_boot_header_pages + num_boot_ramdisk_pages |
| ) # header + vendor_ramdisk |
| image_info_list.append((dtb_offset, info.dtb_size, 'dtb')) |
| |
| create_out_dir(args.out) |
| for offset, size, name in image_info_list: |
| extract_image(offset, size, args.boot_img, os.path.join(args.out, name)) |
| info.image_dir = args.out |
| |
| if info.header_version > 3: |
| vendor_ramdisk_by_name_dir = os.path.join( |
| args.out, 'vendor-ramdisk-by-name') |
| create_out_dir(vendor_ramdisk_by_name_dir) |
| for src, dst in vendor_ramdisk_symlinks: |
| src_pathname = os.path.join('..', src) |
| dst_pathname = os.path.join( |
| vendor_ramdisk_by_name_dir, f'ramdisk_{dst}') |
| if os.path.lexists(dst_pathname): |
| os.remove(dst_pathname) |
| os.symlink(src_pathname, dst_pathname) |
| |
| return info |
| |
| |
| def unpack_image(args): |
| boot_magic = unpack('8s', args.boot_img.read(8))[0].decode() |
| args.boot_img.seek(0) |
| if boot_magic == 'ANDROID!': |
| info = unpack_boot_image(args) |
| elif boot_magic == 'VNDRBOOT': |
| info = unpack_vendor_boot_image(args) |
| else: |
| raise ValueError(f'Not an Android boot image, magic: {boot_magic}') |
| |
| if args.format == 'mkbootimg': |
| mkbootimg_args = info.format_mkbootimg_argument() |
| if args.null: |
| print('\0'.join(mkbootimg_args) + '\0', end='') |
| else: |
| print(shlex.join(mkbootimg_args)) |
| else: |
| print(info.format_pretty_text()) |
| |
| |
| def get_unpack_usage(): |
| return """Output format: |
| |
| * info |
| |
| Pretty-printed info-rich text format suitable for human inspection. |
| |
| * mkbootimg |
| |
| Output shell-escaped (quoted) argument strings that can be used to |
| reconstruct the boot image. For example: |
| |
| $ unpack_bootimg --boot_img vendor_boot.img --out out --format=mkbootimg | |
| tee mkbootimg_args |
| $ sh -c "mkbootimg $(cat mkbootimg_args) --vendor_boot repacked.img" |
| |
| vendor_boot.img and repacked.img would be equivalent. |
| |
| If the -0 option is specified, output unescaped null-terminated argument |
| strings that are suitable to be parsed by a shell script (xargs -0 format): |
| |
| $ unpack_bootimg --boot_img vendor_boot.img --out out --format=mkbootimg \\ |
| -0 | tee mkbootimg_args |
| $ declare -a MKBOOTIMG_ARGS=() |
| $ while IFS= read -r -d '' ARG; do |
| MKBOOTIMG_ARGS+=("${ARG}") |
| done <mkbootimg_args |
| $ mkbootimg "${MKBOOTIMG_ARGS[@]}" --vendor_boot repacked.img |
| """ |
| |
| |
| def parse_cmdline(): |
| """parse command line arguments""" |
| parser = ArgumentParser( |
| formatter_class=RawDescriptionHelpFormatter, |
| description='Unpacks boot, recovery or vendor_boot image.', |
| epilog=get_unpack_usage(), |
| ) |
| parser.add_argument('--boot_img', type=FileType('rb'), required=True, |
| help='path to the boot, recovery or vendor_boot image') |
| parser.add_argument('--out', default='out', |
| help='output directory of the unpacked images') |
| parser.add_argument('--format', choices=['info', 'mkbootimg'], |
| default='info', |
| help='text output format (default: info)') |
| parser.add_argument('-0', '--null', action='store_true', |
| help='output null-terminated argument strings') |
| return parser.parse_args() |
| |
| |
| def main(): |
| """parse arguments and unpack boot image""" |
| args = parse_cmdline() |
| unpack_image(args) |
| |
| |
| if __name__ == '__main__': |
| main() |