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1#
2# Copyright (C) 2013 The Android Open Source Project
3#
4# Licensed under the Apache License, Version 2.0 (the "License");
5# you may not use this file except in compliance with the License.
6# You may obtain a copy of the License at
7#
8#      http://www.apache.org/licenses/LICENSE-2.0
9#
10# Unless required by applicable law or agreed to in writing, software
11# distributed under the License is distributed on an "AS IS" BASIS,
12# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13# See the License for the specific language governing permissions and
14# limitations under the License.
15#
16
17"""Tools for reading, verifying and applying Chrome OS update payloads."""
18
19from __future__ import absolute_import
20from __future__ import print_function
21
22import hashlib
23import io
24import mmap
25import struct
26import zipfile
27
28from update_payload import applier
29from update_payload import checker
30from update_payload import common
31from update_payload import update_metadata_pb2
32from update_payload.error import PayloadError
33
34
35#
36# Helper functions.
37#
38def _ReadInt(file_obj, size, is_unsigned, hasher=None):
39  """Reads a binary-encoded integer from a file.
40
41  It will do the correct conversion based on the reported size and whether or
42  not a signed number is expected. Assumes a network (big-endian) byte
43  ordering.
44
45  Args:
46    file_obj: a file object
47    size: the integer size in bytes (2, 4 or 8)
48    is_unsigned: whether it is signed or not
49    hasher: an optional hasher to pass the value through
50
51  Returns:
52    An "unpacked" (Python) integer value.
53
54  Raises:
55    PayloadError if an read error occurred.
56  """
57  return struct.unpack(common.IntPackingFmtStr(size, is_unsigned),
58                       common.Read(file_obj, size, hasher=hasher))[0]
59
60
61#
62# Update payload.
63#
64class Payload(object):
65  """Chrome OS update payload processor."""
66
67  class _PayloadHeader(object):
68    """Update payload header struct."""
69
70    # Header constants; sizes are in bytes.
71    _MAGIC = b'CrAU'
72    _VERSION_SIZE = 8
73    _MANIFEST_LEN_SIZE = 8
74    _METADATA_SIGNATURE_LEN_SIZE = 4
75
76    def __init__(self):
77      self.version = None
78      self.manifest_len = None
79      self.metadata_signature_len = None
80      self.size = None
81
82    def ReadFromPayload(self, payload_file, hasher=None):
83      """Reads the payload header from a file.
84
85      Reads the payload header from the |payload_file| and updates the |hasher|
86      if one is passed. The parsed header is stored in the _PayloadHeader
87      instance attributes.
88
89      Args:
90        payload_file: a file object
91        hasher: an optional hasher to pass the value through
92
93      Returns:
94        None.
95
96      Raises:
97        PayloadError if a read error occurred or the header is invalid.
98      """
99      # Verify magic
100      magic = common.Read(payload_file, len(self._MAGIC), hasher=hasher)
101      if magic != self._MAGIC:
102        raise PayloadError('invalid payload magic: %s' % magic)
103
104      self.version = _ReadInt(payload_file, self._VERSION_SIZE, True,
105                              hasher=hasher)
106      self.manifest_len = _ReadInt(payload_file, self._MANIFEST_LEN_SIZE, True,
107                                   hasher=hasher)
108      self.size = (len(self._MAGIC) + self._VERSION_SIZE +
109                   self._MANIFEST_LEN_SIZE)
110      self.metadata_signature_len = 0
111
112      if self.version == common.BRILLO_MAJOR_PAYLOAD_VERSION:
113        self.size += self._METADATA_SIGNATURE_LEN_SIZE
114        self.metadata_signature_len = _ReadInt(
115            payload_file, self._METADATA_SIGNATURE_LEN_SIZE, True,
116            hasher=hasher)
117
118  def __init__(self, payload_file, payload_file_offset=0):
119    """Initialize the payload object.
120
121    Args:
122      payload_file: update payload file object open for reading
123      payload_file_offset: the offset of the actual payload
124    """
125    if zipfile.is_zipfile(payload_file):
126      with zipfile.ZipFile(payload_file) as zfp:
127        self.payload_file = zfp.open("payload.bin", "r")
128    elif isinstance(payload_file, str):
129      payload_fp = open(payload_file, "rb")
130      payload_bytes = mmap.mmap(payload_fp.fileno(), 0, access=mmap.ACCESS_READ)
131      self.payload_file = io.BytesIO(payload_bytes)
132    else:
133      self.payload_file = payload_file
134    self.payload_file_offset = payload_file_offset
135    self.manifest_hasher = None
136    self.is_init = False
137    self.header = None
138    self.manifest = None
139    self.data_offset = None
140    self.metadata_signature = None
141    self.metadata_size = None
142
143  def _ReadHeader(self):
144    """Reads and returns the payload header.
145
146    Returns:
147      A payload header object.
148
149    Raises:
150      PayloadError if a read error occurred.
151    """
152    header = self._PayloadHeader()
153    header.ReadFromPayload(self.payload_file, self.manifest_hasher)
154    return header
155
156  def _ReadManifest(self):
157    """Reads and returns the payload manifest.
158
159    Returns:
160      A string containing the payload manifest in binary form.
161
162    Raises:
163      PayloadError if a read error occurred.
164    """
165    if not self.header:
166      raise PayloadError('payload header not present')
167
168    return common.Read(self.payload_file, self.header.manifest_len,
169                       hasher=self.manifest_hasher)
170
171  def _ReadMetadataSignature(self):
172    """Reads and returns the metadata signatures.
173
174    Returns:
175      A string containing the metadata signatures protobuf in binary form or
176      an empty string if no metadata signature found in the payload.
177
178    Raises:
179      PayloadError if a read error occurred.
180    """
181    if not self.header:
182      raise PayloadError('payload header not present')
183
184    return common.Read(
185        self.payload_file, self.header.metadata_signature_len,
186        offset=self.payload_file_offset + self.header.size +
187        self.header.manifest_len)
188
189  def ReadDataBlob(self, offset, length):
190    """Reads and returns a single data blob from the update payload.
191
192    Args:
193      offset: offset to the beginning of the blob from the end of the manifest
194      length: the blob's length
195
196    Returns:
197      A string containing the raw blob data.
198
199    Raises:
200      PayloadError if a read error occurred.
201    """
202    return common.Read(self.payload_file, length,
203                       offset=self.payload_file_offset + self.data_offset +
204                       offset)
205
206  def Init(self):
207    """Initializes the payload object.
208
209    This is a prerequisite for any other public API call.
210
211    Raises:
212      PayloadError if object already initialized or fails to initialize
213      correctly.
214    """
215    if self.is_init:
216      raise PayloadError('payload object already initialized')
217
218    self.manifest_hasher = hashlib.sha256()
219
220    # Read the file header.
221    self.payload_file.seek(self.payload_file_offset)
222    self.header = self._ReadHeader()
223
224    # Read the manifest.
225    manifest_raw = self._ReadManifest()
226    self.manifest = update_metadata_pb2.DeltaArchiveManifest()
227    self.manifest.ParseFromString(manifest_raw)
228
229    # Read the metadata signature (if any).
230    metadata_signature_raw = self._ReadMetadataSignature()
231    if metadata_signature_raw:
232      self.metadata_signature = update_metadata_pb2.Signatures()
233      self.metadata_signature.ParseFromString(metadata_signature_raw)
234
235    self.metadata_size = self.header.size + self.header.manifest_len
236    self.data_offset = self.metadata_size + self.header.metadata_signature_len
237
238    self.is_init = True
239
240  def _AssertInit(self):
241    """Raises an exception if the object was not initialized."""
242    if not self.is_init:
243      raise PayloadError('payload object not initialized')
244
245  def ResetFile(self):
246    """Resets the offset of the payload file to right past the manifest."""
247    self.payload_file.seek(self.payload_file_offset + self.data_offset)
248
249  def IsDelta(self):
250    """Returns True iff the payload appears to be a delta."""
251    self._AssertInit()
252    return (any(partition.HasField('old_partition_info')
253                for partition in self.manifest.partitions))
254
255  def IsFull(self):
256    """Returns True iff the payload appears to be a full."""
257    return not self.IsDelta()
258
259  def Check(self, pubkey_file_name=None, metadata_sig_file=None,
260            metadata_size=0, report_out_file=None, assert_type=None,
261            block_size=0, part_sizes=None, allow_unhashed=False,
262            disabled_tests=()):
263    """Checks the payload integrity.
264
265    Args:
266      pubkey_file_name: public key used for signature verification
267      metadata_sig_file: metadata signature, if verification is desired
268      metadata_size: metadata size, if verification is desired
269      report_out_file: file object to dump the report to
270      assert_type: assert that payload is either 'full' or 'delta'
271      block_size: expected filesystem / payload block size
272      part_sizes: map of partition label to (physical) size in bytes
273      allow_unhashed: allow unhashed operation blobs
274      disabled_tests: list of tests to disable
275
276    Raises:
277      PayloadError if payload verification failed.
278    """
279    self._AssertInit()
280
281    # Create a short-lived payload checker object and run it.
282    helper = checker.PayloadChecker(
283        self, assert_type=assert_type, block_size=block_size,
284        allow_unhashed=allow_unhashed, disabled_tests=disabled_tests)
285    helper.Run(pubkey_file_name=pubkey_file_name,
286               metadata_sig_file=metadata_sig_file,
287               metadata_size=metadata_size,
288               part_sizes=part_sizes,
289               report_out_file=report_out_file)
290
291  def Apply(self, new_parts, old_parts=None, bsdiff_in_place=True,
292            bspatch_path=None, puffpatch_path=None,
293            truncate_to_expected_size=True):
294    """Applies the update payload.
295
296    Args:
297      new_parts: map of partition name to dest partition file
298      old_parts: map of partition name to partition file (optional)
299      bsdiff_in_place: whether to perform BSDIFF operations in-place (optional)
300      bspatch_path: path to the bspatch binary (optional)
301      puffpatch_path: path to the puffpatch binary (optional)
302      truncate_to_expected_size: whether to truncate the resulting partitions
303                                 to their expected sizes, as specified in the
304                                 payload (optional)
305
306    Raises:
307      PayloadError if payload application failed.
308    """
309    self._AssertInit()
310
311    # Create a short-lived payload applier object and run it.
312    helper = applier.PayloadApplier(
313        self, bsdiff_in_place=bsdiff_in_place, bspatch_path=bspatch_path,
314        puffpatch_path=puffpatch_path,
315        truncate_to_expected_size=truncate_to_expected_size)
316    helper.Run(new_parts, old_parts=old_parts)
317