platform_build/tools/releasetools/fsverity_manifest_generator.py

#!/usr/bin/env python3
#
# Copyright 2022 Google Inc. All rights reserved.
#
# 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.

"""
`fsverity_manifest_generator` generates build manifest APK file containing
digests of target files. The APK file is signed so the manifest inside the APK
can be trusted.
"""

import argparse
import common
import os
import subprocess
import sys
from fsverity_digests_pb2 import FSVerityDigests

HASH_ALGORITHM = 'sha256'

def _digest(fsverity_path, input_file):
  cmd = [fsverity_path, 'digest', input_file]
  cmd.extend(['--compact'])
  cmd.extend(['--hash-alg', HASH_ALGORITHM])
  out = subprocess.check_output(cmd, universal_newlines=True).strip()
  return bytes(bytearray.fromhex(out))

if __name__ == '__main__':
  p = argparse.ArgumentParser()
  p.add_argument(
      '--output',
      help='Path to the output manifest APK',
      required=True)
  p.add_argument(
      '--fsverity-path',
      help='path to the fsverity program',
      required=True)
  p.add_argument(
      '--aapt2-path',
      help='path to the aapt2 program',
      required=True)
  p.add_argument(
      '--min-sdk-version',
      help='minimum supported sdk version of the generated manifest apk',
      required=True)
  p.add_argument(
      '--framework-res',
      help='path to framework-res.apk',
      required=True)
  p.add_argument(
      '--apksigner-path',
      help='path to the apksigner program',
      required=True)
  p.add_argument(
      '--apk-key-path',
      help='path to the apk key',
      required=True)
  p.add_argument(
      '--apk-manifest-path',
      help='path to AndroidManifest.xml',
      required=True)
  p.add_argument(
      '--base-dir',
      help='directory to use as a relative root for the inputs',
      required=True)
  p.add_argument(
      'inputs',
      nargs='+',
      help='input file for the build manifest')
  args = p.parse_args(sys.argv[1:])

  digests = FSVerityDigests()
  for f in sorted(args.inputs):
    # f is a full path for now; make it relative so it starts with {mount_point}/
    digest = digests.digests[os.path.relpath(f, args.base_dir)]
    digest.digest = _digest(args.fsverity_path, f)
    digest.hash_alg = HASH_ALGORITHM

  temp_dir = common.MakeTempDir()

  os.mkdir(os.path.join(temp_dir, "assets"))
  metadata_path = os.path.join(temp_dir, "assets", "build_manifest.pb")
  with open(metadata_path, "wb") as f:
    f.write(digests.SerializeToString())

  common.RunAndCheckOutput([args.aapt2_path, "link",
      "-A", os.path.join(temp_dir, "assets"),
      "-o", args.output,
      "--min-sdk-version", args.min_sdk_version,
      "-I", args.framework_res,
      "--manifest", args.apk_manifest_path])
  common.RunAndCheckOutput([args.apksigner_path, "sign", "--in", args.output,
      "--cert", args.apk_key_path + ".x509.pem",
      "--key", args.apk_key_path + ".pk8"])