79 lines
2.5 KiB
Python
Executable File
79 lines
2.5 KiB
Python
Executable File
#! /usr/bin/env python
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import os
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import sys
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import struct
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import tempfile
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import commands
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VERSION = 0
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MAGIC_NUMBER = 0xb001b001
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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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status, output = commands.getstatusoutput(cmd)
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print output
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if status:
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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):
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table_len = len(verity_table)
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block = struct.pack("II256sI", MAGIC_NUMBER, 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):
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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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cmd = " ".join((signer_path, 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 + (METADATA_SIZE / BLOCK_SIZE),
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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,
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salt, block_device, signer_path, signing_key):
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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)
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# build the metadata block
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metadata_block = build_metadata_block(verity_table, signature)
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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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if len(sys.argv) == 3 and sys.argv[1] == "-s":
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print get_verity_metadata_size(int(sys.argv[2]))
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elif len(sys.argv) == 8:
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data_image_blocks = int(sys.argv[1]) / 4096
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metadata_image = sys.argv[2]
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root_hash = sys.argv[3]
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salt = sys.argv[4]
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block_device = sys.argv[5]
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signer_path = sys.argv[6]
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signing_key = sys.argv[7]
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build_verity_metadata(data_image_blocks, metadata_image, root_hash,
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salt, block_device, signer_path, signing_key)
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else:
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exit(-1)
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