1#! /usr/bin/env python
2#
3# Copyright (C) 2013 The Android Open Source Project
4#
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
8#
9#      http://www.apache.org/licenses/LICENSE-2.0
10#
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.
16
17import argparse
18import os
19import sys
20import struct
21import shlex
22import subprocess
23import tempfile
24
25VERSION = 0
26MAGIC_NUMBER = 0xb001b001
27BLOCK_SIZE = 4096
28METADATA_SIZE = BLOCK_SIZE * 8
29
30def run(cmd):
31    p = subprocess.Popen(cmd, stdout=subprocess.PIPE)
32    output, _ = p.communicate()
33    print output
34    if p.returncode:
35        exit(-1)
36
37def get_verity_metadata_size(data_size):
38    return METADATA_SIZE
39
40def build_metadata_block(verity_table, signature):
41    table_len = len(verity_table)
42    block = struct.pack("II256sI", MAGIC_NUMBER, VERSION, signature, table_len)
43    block += verity_table
44    block = block.ljust(METADATA_SIZE, '\x00')
45    return block
46
47def sign_verity_table(table, signer_path, key_path, signer_args=None):
48    with tempfile.NamedTemporaryFile(suffix='.table') as table_file:
49        with tempfile.NamedTemporaryFile(suffix='.sig') as signature_file:
50            table_file.write(table)
51            table_file.flush()
52            if signer_args is None:
53              cmd = [signer_path, table_file.name, key_path, signature_file.name]
54            else:
55              args_list = shlex.split(signer_args)
56              cmd = [signer_path] + args_list + [table_file.name, key_path, signature_file.name]
57            print cmd
58            run(cmd)
59            return signature_file.read()
60
61def build_verity_table(block_device, data_blocks, root_hash, salt):
62    table = "1 %s %s %s %s %s %s sha256 %s %s"
63    table %= (  block_device,
64                block_device,
65                BLOCK_SIZE,
66                BLOCK_SIZE,
67                data_blocks,
68                data_blocks,
69                root_hash,
70                salt)
71    return table
72
73def build_verity_metadata(data_blocks, metadata_image, root_hash, salt,
74        block_device, signer_path, signing_key, signer_args=None):
75    # build the verity table
76    verity_table = build_verity_table(block_device, data_blocks, root_hash, salt)
77    # build the verity table signature
78    signature = sign_verity_table(verity_table, signer_path, signing_key, signer_args)
79    # build the metadata block
80    metadata_block = build_metadata_block(verity_table, signature)
81    # write it to the outfile
82    with open(metadata_image, "wb") as f:
83        f.write(metadata_block)
84
85if __name__ == "__main__":
86    parser = argparse.ArgumentParser()
87    subparsers = parser.add_subparsers()
88
89    parser_size = subparsers.add_parser('size')
90    parser_size.add_argument('partition_size', type=int, action='store', help='partition size')
91    parser_size.set_defaults(dest='size')
92
93    parser_build = subparsers.add_parser('build')
94    parser_build.add_argument('blocks', type=int, help='data image blocks')
95    parser_build.add_argument('metadata_image', action='store', help='metadata image')
96    parser_build.add_argument('root_hash', action='store', help='root hash')
97    parser_build.add_argument('salt', action='store', help='salt')
98    parser_build.add_argument('block_device', action='store', help='block device')
99    parser_build.add_argument('signer_path', action='store', help='verity signer path')
100    parser_build.add_argument('signing_key', action='store', help='verity signing key')
101    parser_build.add_argument('--signer_args', action='store', help='verity signer args')
102    parser_build.set_defaults(dest='build')
103
104    args = parser.parse_args()
105
106    if args.dest == 'size':
107        print get_verity_metadata_size(args.partition_size)
108    else:
109        build_verity_metadata(args.blocks / 4096, args.metadata_image,
110                              args.root_hash, args.salt, args.block_device,
111                              args.signer_path, args.signing_key,
112                              args.signer_args)
113