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118 lines
4.5 KiB
118 lines
4.5 KiB
#! /usr/bin/env python
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#
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# Copyright (C) 2013 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 argparse
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import os
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import sys
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import struct
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import shlex
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import subprocess
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import tempfile
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VERSION = 0
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MAGIC_NUMBER = 0xb001b001
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MAGIC_DISABLE = 0x46464f56 # "VOFF"
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BLOCK_SIZE = 4096
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METADATA_SIZE = BLOCK_SIZE * 8
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def run(cmd):
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p = subprocess.Popen(cmd, stdout=subprocess.PIPE)
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output, _ = p.communicate()
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print output
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if p.returncode:
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exit(-1)
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def get_verity_metadata_size(data_size):
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return METADATA_SIZE
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def build_metadata_block(verity_table, signature, verity_disable=False):
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table_len = len(verity_table)
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magic = MAGIC_DISABLE if verity_disable else MAGIC_NUMBER
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block = struct.pack("II256sI", magic, VERSION, signature, table_len)
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block += verity_table
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block = block.ljust(METADATA_SIZE, '\x00')
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return block
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def sign_verity_table(table, signer_path, key_path, signer_args=None):
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with tempfile.NamedTemporaryFile(suffix='.table') as table_file:
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with tempfile.NamedTemporaryFile(suffix='.sig') as signature_file:
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table_file.write(table)
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table_file.flush()
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if signer_args is None:
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cmd = [signer_path, table_file.name, key_path, signature_file.name]
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else:
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args_list = shlex.split(signer_args)
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cmd = [signer_path] + args_list + [table_file.name, key_path, signature_file.name]
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print cmd
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run(cmd)
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return signature_file.read()
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def build_verity_table(block_device, data_blocks, root_hash, salt):
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table = "1 %s %s %s %s %s %s sha256 %s %s"
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table %= ( block_device,
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block_device,
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BLOCK_SIZE,
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BLOCK_SIZE,
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data_blocks,
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data_blocks,
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root_hash,
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salt)
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return table
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def build_verity_metadata(data_blocks, metadata_image, root_hash, salt,
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block_device, signer_path, signing_key, signer_args=None,
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verity_disable=False):
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# build the verity table
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verity_table = build_verity_table(block_device, data_blocks, root_hash, salt)
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# build the verity table signature
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signature = sign_verity_table(verity_table, signer_path, signing_key, signer_args)
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# build the metadata block
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metadata_block = build_metadata_block(verity_table, signature, verity_disable)
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# write it to the outfile
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with open(metadata_image, "wb") as f:
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f.write(metadata_block)
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if __name__ == "__main__":
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parser = argparse.ArgumentParser()
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subparsers = parser.add_subparsers()
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parser_size = subparsers.add_parser('size')
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parser_size.add_argument('partition_size', type=int, action='store', help='partition size')
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parser_size.set_defaults(dest='size')
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parser_build = subparsers.add_parser('build')
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parser_build.add_argument('blocks', type=int, help='data image blocks')
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parser_build.add_argument('metadata_image', action='store', help='metadata image')
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parser_build.add_argument('root_hash', action='store', help='root hash')
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parser_build.add_argument('salt', action='store', help='salt')
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parser_build.add_argument('block_device', action='store', help='block device')
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parser_build.add_argument('signer_path', action='store', help='verity signer path')
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parser_build.add_argument('signing_key', action='store', help='verity signing key')
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parser_build.add_argument('--signer_args', action='store', help='verity signer args')
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parser_build.add_argument('--verity_disable', action='store_true',
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default=False, help='disable verity')
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parser_build.set_defaults(dest='build')
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args = parser.parse_args()
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if args.dest == 'size':
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print get_verity_metadata_size(args.partition_size)
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else:
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build_verity_metadata(args.blocks / 4096, args.metadata_image,
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args.root_hash, args.salt, args.block_device,
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args.signer_path, args.signing_key,
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args.signer_args, args.verity_disable)
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