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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 tempfile
22import commands
23
24VERSION = 0
25MAGIC_NUMBER = 0xb001b001
26BLOCK_SIZE = 4096
27METADATA_SIZE = BLOCK_SIZE * 8
28
29def run(cmd):
30    status, output = commands.getstatusoutput(cmd)
31    print output
32    if status:
33        exit(-1)
34
35def get_verity_metadata_size(data_size):
36    return METADATA_SIZE
37
38def build_metadata_block(verity_table, signature):
39    table_len = len(verity_table)
40    block = struct.pack("II256sI", MAGIC_NUMBER, VERSION, signature, table_len)
41    block += verity_table
42    block = block.ljust(METADATA_SIZE, '\x00')
43    return block
44
45def sign_verity_table(table, signer_path, key_path, signer_args=None):
46    if signer_args is None:
47        signer_args = ''
48
49    with tempfile.NamedTemporaryFile(suffix='.table') as table_file:
50        with tempfile.NamedTemporaryFile(suffix='.sig') as signature_file:
51            table_file.write(table)
52            table_file.flush()
53            cmd = " ".join((signer_path, signer_args, table_file.name,
54                            key_path, signature_file.name))
55            print cmd
56            run(cmd)
57            return signature_file.read()
58
59def 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,
62                block_device,
63                BLOCK_SIZE,
64                BLOCK_SIZE,
65                data_blocks,
66                data_blocks,
67                root_hash,
68                salt)
69    return table
70
71def 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)
82
83if __name__ == "__main__":
84    parser = argparse.ArgumentParser()
85    subparsers = parser.add_subparsers()
86
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')
90
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')
101
102    args = parser.parse_args()
103
104    if args.dest == 'size':
105        print get_verity_metadata_size(args.partition_size)
106    else:
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,
110                              args.signer_args)
111