#!/usr/bin/env python
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#
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# Copyright (C) 2019 The Android Open Source Project
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import logging
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import os.path
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import re
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import shlex
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import sys
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import zipfile
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import common
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logger = logging.getLogger(__name__)
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OPTIONS = common.OPTIONS
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class ApexInfoError(Exception):
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"""An Exception raised during Apex Information command."""
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def __init__(self, message):
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Exception.__init__(self, message)
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class ApexSigningError(Exception):
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"""An Exception raised during Apex Payload signing."""
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def __init__(self, message):
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Exception.__init__(self, message)
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def SignApexPayload(payload_file, payload_key_path, payload_key_name, algorithm,
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salt, signing_args=None):
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"""Signs a given payload_file with the payload key."""
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# Add the new footer. Old footer, if any, will be replaced by avbtool.
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cmd = ['avbtool', 'add_hashtree_footer',
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'--do_not_generate_fec',
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'--algorithm', algorithm,
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'--key', payload_key_path,
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'--prop', 'apex.key:{}'.format(payload_key_name),
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'--image', payload_file,
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'--salt', salt]
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if signing_args:
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cmd.extend(shlex.split(signing_args))
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try:
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common.RunAndCheckOutput(cmd)
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except common.ExternalError as e:
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raise ApexSigningError, \
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'Failed to sign APEX payload {} with {}:\n{}'.format(
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payload_file, payload_key_path, e), sys.exc_info()[2]
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# Verify the signed payload image with specified public key.
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logger.info('Verifying %s', payload_file)
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VerifyApexPayload(payload_file, payload_key_path)
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def VerifyApexPayload(payload_file, payload_key):
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"""Verifies the APEX payload signature with the given key."""
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cmd = ['avbtool', 'verify_image', '--image', payload_file,
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'--key', payload_key]
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try:
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common.RunAndCheckOutput(cmd)
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except common.ExternalError as e:
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raise ApexSigningError, \
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'Failed to validate payload signing for {} with {}:\n{}'.format(
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payload_file, payload_key, e), sys.exc_info()[2]
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def ParseApexPayloadInfo(payload_path):
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"""Parses the APEX payload info.
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Args:
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payload_path: The path to the payload image.
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Raises:
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ApexInfoError on parsing errors.
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Returns:
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A dict that contains payload property-value pairs. The dict should at least
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contain Algorithm, Salt and apex.key.
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"""
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if not os.path.exists(payload_path):
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raise ApexInfoError('Failed to find image: {}'.format(payload_path))
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cmd = ['avbtool', 'info_image', '--image', payload_path]
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try:
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output = common.RunAndCheckOutput(cmd)
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except common.ExternalError as e:
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raise ApexInfoError, \
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'Failed to get APEX payload info for {}:\n{}'.format(
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payload_path, e), sys.exc_info()[2]
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# Extract the Algorithm / Salt / Prop info from payload (i.e. an image signed
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# with avbtool). For example,
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# Algorithm: SHA256_RSA4096
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PAYLOAD_INFO_PATTERN = (
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r'^\s*(?P<key>Algorithm|Salt|Prop)\:\s*(?P<value>.*?)$')
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payload_info_matcher = re.compile(PAYLOAD_INFO_PATTERN)
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payload_info = {}
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for line in output.split('\n'):
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line_info = payload_info_matcher.match(line)
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if not line_info:
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continue
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key, value = line_info.group('key'), line_info.group('value')
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if key == 'Prop':
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# Further extract the property key-value pair, from a 'Prop:' line. For
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# example,
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# Prop: apex.key -> 'com.android.runtime'
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# Note that avbtool writes single or double quotes around values.
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PROPERTY_DESCRIPTOR_PATTERN = r'^\s*(?P<key>.*?)\s->\s*(?P<value>.*?)$'
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prop_matcher = re.compile(PROPERTY_DESCRIPTOR_PATTERN)
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prop = prop_matcher.match(value)
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if not prop:
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raise ApexInfoError(
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'Failed to parse prop string {}'.format(value))
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prop_key, prop_value = prop.group('key'), prop.group('value')
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if prop_key == 'apex.key':
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# avbtool dumps the prop value with repr(), which contains single /
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# double quotes that we don't want.
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payload_info[prop_key] = prop_value.strip('\"\'')
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else:
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payload_info[key] = value
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# Sanity check.
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for key in ('Algorithm', 'Salt', 'apex.key'):
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if key not in payload_info:
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raise ApexInfoError(
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'Failed to find {} prop in {}'.format(key, payload_path))
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return payload_info
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def SignApex(apex_data, payload_key, container_key, container_pw,
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codename_to_api_level_map, signing_args=None):
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"""Signs the current APEX with the given payload/container keys.
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Args:
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apex_data: Raw APEX data.
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payload_key: The path to payload signing key (w/ extension).
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container_key: The path to container signing key (w/o extension).
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container_pw: The matching password of the container_key, or None.
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codename_to_api_level_map: A dict that maps from codename to API level.
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signing_args: Additional args to be passed to the payload signer.
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Returns:
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The path to the signed APEX file.
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"""
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apex_file = common.MakeTempFile(prefix='apex-', suffix='.apex')
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with open(apex_file, 'wb') as apex_fp:
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apex_fp.write(apex_data)
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APEX_PAYLOAD_IMAGE = 'apex_payload.img'
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APEX_PUBKEY = 'apex_pubkey'
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# 1a. Extract and sign the APEX_PAYLOAD_IMAGE entry with the given
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# payload_key.
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payload_dir = common.MakeTempDir(prefix='apex-payload-')
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with zipfile.ZipFile(apex_file) as apex_fd:
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payload_file = apex_fd.extract(APEX_PAYLOAD_IMAGE, payload_dir)
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payload_info = ParseApexPayloadInfo(payload_file)
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SignApexPayload(
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payload_file,
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payload_key,
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payload_info['apex.key'],
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payload_info['Algorithm'],
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payload_info['Salt'],
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signing_args)
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# 1b. Update the embedded payload public key.
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payload_public_key = common.ExtractAvbPublicKey(payload_key)
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common.ZipDelete(apex_file, APEX_PAYLOAD_IMAGE)
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common.ZipDelete(apex_file, APEX_PUBKEY)
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apex_zip = zipfile.ZipFile(apex_file, 'a')
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common.ZipWrite(apex_zip, payload_file, arcname=APEX_PAYLOAD_IMAGE)
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common.ZipWrite(apex_zip, payload_public_key, arcname=APEX_PUBKEY)
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common.ZipClose(apex_zip)
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# 2. Align the files at page boundary (same as in apexer).
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aligned_apex = common.MakeTempFile(prefix='apex-container-', suffix='.apex')
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common.RunAndCheckOutput(['zipalign', '-f', '4096', apex_file, aligned_apex])
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# 3. Sign the APEX container with container_key.
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signed_apex = common.MakeTempFile(prefix='apex-container-', suffix='.apex')
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# Specify the 4K alignment when calling SignApk.
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extra_signapk_args = OPTIONS.extra_signapk_args[:]
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extra_signapk_args.extend(['-a', '4096'])
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common.SignFile(
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aligned_apex,
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signed_apex,
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container_key,
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container_pw,
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codename_to_api_level_map=codename_to_api_level_map,
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extra_signapk_args=extra_signapk_args)
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return signed_apex
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