3 # Copyright (C) 2013 The Android Open Source Project
5 # Licensed under the Apache License, Version 2.0 (the "License");
6 # you may not use this file except in compliance with the License.
7 # You may obtain a copy of the License at
9 # http://www.apache.org/licenses/LICENSE-2.0
11 # Unless required by applicable law or agreed to in writing, software
12 # distributed under the License is distributed on an "AS IS" BASIS,
13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 # See the License for the specific language governing permissions and
15 # limitations under the License.
25 MAGIC_NUMBER = 0xb001b001
27 METADATA_SIZE = BLOCK_SIZE * 8
30 status, output = commands.getstatusoutput(cmd)
35 def get_verity_metadata_size(data_size):
38 def build_metadata_block(verity_table, signature):
39 table_len = len(verity_table)
40 block = struct.pack("II256sI", MAGIC_NUMBER, VERSION, signature, table_len)
42 block = block.ljust(METADATA_SIZE, '\x00')
45 def sign_verity_table(table, signer_path, key_path, signer_args=None):
46 if signer_args is None:
49 with tempfile.NamedTemporaryFile(suffix='.table') as table_file:
50 with tempfile.NamedTemporaryFile(suffix='.sig') as signature_file:
51 table_file.write(table)
53 cmd = " ".join((signer_path, signer_args, table_file.name,
54 key_path, signature_file.name))
57 return signature_file.read()
59 def build_verity_table(block_device, data_blocks, root_hash, salt):
60 table = "1 %s %s %s %s %s %s sha256 %s %s"
61 table %= ( block_device,
71 def build_verity_metadata(data_blocks, metadata_image, root_hash, salt,
72 block_device, signer_path, signing_key, signer_args=None):
73 # build the verity table
74 verity_table = build_verity_table(block_device, data_blocks, root_hash, salt)
75 # build the verity table signature
76 signature = sign_verity_table(verity_table, signer_path, signing_key, signer_args)
77 # build the metadata block
78 metadata_block = build_metadata_block(verity_table, signature)
79 # write it to the outfile
80 with open(metadata_image, "wb") as f:
81 f.write(metadata_block)
83 if __name__ == "__main__":
84 parser = argparse.ArgumentParser()
85 subparsers = parser.add_subparsers()
87 parser_size = subparsers.add_parser('size')
88 parser_size.add_argument('partition_size', type=int, action='store', help='partition size')
89 parser_size.set_defaults(dest='size')
91 parser_build = subparsers.add_parser('build')
92 parser_build.add_argument('blocks', type=int, help='data image blocks')
93 parser_build.add_argument('metadata_image', action='store', help='metadata image')
94 parser_build.add_argument('root_hash', action='store', help='root hash')
95 parser_build.add_argument('salt', action='store', help='salt')
96 parser_build.add_argument('block_device', action='store', help='block device')
97 parser_build.add_argument('signer_path', action='store', help='verity signer path')
98 parser_build.add_argument('signing_key', action='store', help='verity signing key')
99 parser_build.add_argument('--signer_args', action='store', help='verity signer args')
100 parser_build.set_defaults(dest='build')
102 args = parser.parse_args()
104 if args.dest == 'size':
105 print get_verity_metadata_size(args.partition_size)
107 build_verity_metadata(args.blocks / 4096, args.metadata_image,
108 args.root_hash, args.salt, args.block_device,
109 args.signer_path, args.signing_key,