| # Copyright (c) 2013 The Chromium OS Authors. All rights reserved. |
| # Use of this source code is governed by a BSD-style license that can be |
| # found in the LICENSE file. |
| |
| """Tools for reading, verifying and applying Chrome OS update payloads.""" |
| |
| import hashlib |
| import struct |
| |
| import applier |
| import block_tracer |
| import checker |
| import common |
| from error import PayloadError |
| import update_metadata_pb2 |
| |
| |
| # |
| # Helper functions. |
| # |
| def _ReadInt(file_obj, size, is_unsigned, hasher=None): |
| """Reads a binary-encoded integer from a file. |
| |
| It will do the correct conversion based on the reported size and whether or |
| not a signed number is expected. Assumes a network (big-endian) byte |
| ordering. |
| |
| Args: |
| file_obj: a file object |
| size: the integer size in bytes (2, 4 or 8) |
| is_unsigned: whether it is signed or not |
| hasher: an optional hasher to pass the value through |
| Returns: |
| An "unpacked" (Python) integer value. |
| Raises: |
| PayloadError if an read error occurred. |
| |
| """ |
| return struct.unpack(common.IntPackingFmtStr(size, is_unsigned), |
| common.Read(file_obj, size, hasher=hasher))[0] |
| |
| |
| # |
| # Update payload. |
| # |
| class Payload(object): |
| """Chrome OS update payload processor.""" |
| |
| class _PayloadHeader(object): |
| """Update payload header struct.""" |
| |
| def __init__(self, version, manifest_len): |
| self.version = version |
| self.manifest_len = manifest_len |
| |
| # Header constants; sizes are in bytes. |
| _MAGIC = 'CrAU' |
| _VERSION_SIZE = 8 |
| _MANIFEST_LEN_SIZE = 8 |
| |
| def __init__(self, payload_file): |
| """Initialize the payload object. |
| |
| Args: |
| payload_file: update payload file object open for reading |
| |
| """ |
| self.payload_file = payload_file |
| self.manifest_hasher = None |
| self.is_init = False |
| self.header = None |
| self.manifest = None |
| self.data_offset = 0 |
| |
| def _ReadHeader(self): |
| """Reads and returns the payload header. |
| |
| Returns: |
| A payload header object. |
| Raises: |
| PayloadError if a read error occurred. |
| |
| """ |
| # Verify magic |
| magic = common.Read(self.payload_file, len(self._MAGIC), |
| hasher=self.manifest_hasher) |
| if magic != self._MAGIC: |
| raise PayloadError('invalid payload magic: %s' % magic) |
| |
| return self._PayloadHeader( |
| _ReadInt(self.payload_file, self._VERSION_SIZE, True, |
| hasher=self.manifest_hasher), |
| _ReadInt(self.payload_file, self._MANIFEST_LEN_SIZE, True, |
| hasher=self.manifest_hasher)) |
| |
| def _ReadManifest(self): |
| """Reads and returns the payload manifest. |
| |
| Returns: |
| A string containing the payload manifest in binary form. |
| Raises: |
| PayloadError if a read error occurred. |
| |
| """ |
| if not self.header: |
| raise PayloadError('payload header not present') |
| |
| return common.Read(self.payload_file, self.header.manifest_len, |
| hasher=self.manifest_hasher) |
| |
| def ReadDataBlob(self, offset, length): |
| """Reads and returns a single data blob from the update payload. |
| |
| Args: |
| offset: offset to the beginning of the blob from the end of the manifest |
| length: the blob's length |
| Returns: |
| A string containing the raw blob data. |
| Raises: |
| PayloadError if a read error occurred. |
| |
| """ |
| return common.Read(self.payload_file, length, |
| offset=self.data_offset + offset) |
| |
| def Init(self): |
| """Initializes the payload object. |
| |
| This is a prerequisite for any other public API call. |
| |
| Raises: |
| PayloadError if object already initialized or fails to initialize |
| correctly. |
| |
| """ |
| if self.is_init: |
| raise PayloadError('payload object already initialized') |
| |
| # Initialize hash context. |
| # pylint: disable=E1101 |
| self.manifest_hasher = hashlib.sha256() |
| |
| # Read the file header. |
| self.header = self._ReadHeader() |
| |
| # Read the manifest. |
| manifest_raw = self._ReadManifest() |
| self.manifest = update_metadata_pb2.DeltaArchiveManifest() |
| self.manifest.ParseFromString(manifest_raw) |
| |
| # Store data offset. |
| self.data_offset = (len(self._MAGIC) + self._VERSION_SIZE + |
| self._MANIFEST_LEN_SIZE + self.header.manifest_len) |
| |
| self.is_init = True |
| |
| def Describe(self): |
| """Emits the payload embedded description data to standard output.""" |
| def _DescribeImageInfo(description, image_info): |
| def _DisplayIndentedValue(name, value): |
| print ' {:<14} {}'.format(name+':', value) |
| |
| print '%s:' % description |
| _DisplayIndentedValue('Channel', image_info.channel) |
| _DisplayIndentedValue('Board', image_info.board) |
| _DisplayIndentedValue('Version', image_info.version) |
| _DisplayIndentedValue('Key', image_info.key) |
| |
| if image_info.build_channel != image_info.channel: |
| _DisplayIndentedValue('Build channel', image_info.build_channel) |
| |
| if image_info.build_version != image_info.version: |
| _DisplayIndentedValue('Build version', image_info.build_version) |
| |
| if self.manifest.HasField('old_image_info'): |
| # pylint: disable=E1101 |
| _DescribeImageInfo('Old Image', self.manifest.old_image_info) |
| |
| if self.manifest.HasField('new_image_info'): |
| # pylint: disable=E1101 |
| _DescribeImageInfo('New Image', self.manifest.new_image_info) |
| |
| def _AssertInit(self): |
| """Raises an exception if the object was not initialized.""" |
| if not self.is_init: |
| raise PayloadError('payload object not initialized') |
| |
| def ResetFile(self): |
| """Resets the offset of the payload file to right past the manifest.""" |
| self.payload_file.seek(self.data_offset) |
| |
| def IsDelta(self): |
| """Returns True iff the payload appears to be a delta.""" |
| self._AssertInit() |
| return (self.manifest.HasField('old_kernel_info') or |
| self.manifest.HasField('old_rootfs_info')) |
| |
| def IsFull(self): |
| """Returns True iff the payload appears to be a full.""" |
| return not self.IsDelta() |
| |
| def Check(self, pubkey_file_name=None, metadata_sig_file=None, |
| report_out_file=None, assert_type=None, block_size=0, |
| rootfs_part_size=0, kernel_part_size=0, allow_unhashed=False, |
| disabled_tests=()): |
| """Checks the payload integrity. |
| |
| Args: |
| pubkey_file_name: public key used for signature verification |
| metadata_sig_file: metadata signature, if verification is desired |
| report_out_file: file object to dump the report to |
| assert_type: assert that payload is either 'full' or 'delta' |
| block_size: expected filesystem / payload block size |
| rootfs_part_size: the size of (physical) rootfs partitions in bytes |
| kernel_part_size: the size of (physical) kernel partitions in bytes |
| allow_unhashed: allow unhashed operation blobs |
| disabled_tests: list of tests to disable |
| Raises: |
| PayloadError if payload verification failed. |
| |
| """ |
| self._AssertInit() |
| |
| # Create a short-lived payload checker object and run it. |
| helper = checker.PayloadChecker( |
| self, assert_type=assert_type, block_size=block_size, |
| allow_unhashed=allow_unhashed, disabled_tests=disabled_tests) |
| helper.Run(pubkey_file_name=pubkey_file_name, |
| metadata_sig_file=metadata_sig_file, |
| rootfs_part_size=rootfs_part_size, |
| kernel_part_size=kernel_part_size, |
| report_out_file=report_out_file) |
| |
| def Apply(self, new_kernel_part, new_rootfs_part, old_kernel_part=None, |
| old_rootfs_part=None, bsdiff_in_place=True, bspatch_path=None, |
| truncate_to_expected_size=True): |
| """Applies the update payload. |
| |
| Args: |
| new_kernel_part: name of dest kernel partition file |
| new_rootfs_part: name of dest rootfs partition file |
| old_kernel_part: name of source kernel partition file (optional) |
| old_rootfs_part: name of source rootfs partition file (optional) |
| bsdiff_in_place: whether to perform BSDIFF operations in-place (optional) |
| bspatch_path: path to the bspatch binary (optional) |
| truncate_to_expected_size: whether to truncate the resulting partitions |
| to their expected sizes, as specified in the |
| payload (optional) |
| Raises: |
| PayloadError if payload application failed. |
| |
| """ |
| self._AssertInit() |
| |
| # Create a short-lived payload applier object and run it. |
| helper = applier.PayloadApplier( |
| self, bsdiff_in_place=bsdiff_in_place, bspatch_path=bspatch_path, |
| truncate_to_expected_size=truncate_to_expected_size) |
| helper.Run(new_kernel_part, new_rootfs_part, |
| old_kernel_part=old_kernel_part, |
| old_rootfs_part=old_rootfs_part) |
| |
| def TraceBlock(self, block, skip, trace_out_file, is_kernel): |
| """Traces the origin(s) of a given dest partition block. |
| |
| The tracing tries to find origins transitively, when possible (it currently |
| only works for move operations, where the mapping of src/dst is |
| one-to-one). It will dump a list of operations and source blocks |
| responsible for the data in the given dest block. |
| |
| Args: |
| block: the block number whose origin to trace |
| skip: the number of first origin mappings to skip |
| trace_out_file: file object to dump the trace to |
| is_kernel: trace through kernel (True) or rootfs (False) operations |
| |
| """ |
| self._AssertInit() |
| |
| # Create a short-lived payload block tracer object and run it. |
| helper = block_tracer.PayloadBlockTracer(self) |
| helper.Run(block, skip, trace_out_file, is_kernel) |
