46901fb8ca
In Append2Simg and Append in verity_utils.py, we catch and rethrow
exceptions as BuildVerityImageError. However, this suppresses the
traceback from the original exception which usually indicates the actual
cause. We can better handle this with the raise statement in Python 3,
which is however unavailable in Python 2.
This CL logs the exception before rethrowing to retain the useful bits.
Test: Inject an error to append2simg. `m -j systemimage` with
aosp_marlin-userdebug. Check the output.
Change-Id: I0c2f57d6023fa1038256b85fa98d57ad0244a70d
551 lines
18 KiB
Python
551 lines
18 KiB
Python
#!/usr/bin/env python
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#
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# Copyright (C) 2018 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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from __future__ import print_function
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import logging
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import os.path
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import shlex
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import struct
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import common
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import sparse_img
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from rangelib import RangeSet
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logger = logging.getLogger(__name__)
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OPTIONS = common.OPTIONS
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BLOCK_SIZE = common.BLOCK_SIZE
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FIXED_SALT = "aee087a5be3b982978c923f566a94613496b417f2af592639bc80d141e34dfe7"
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class BuildVerityImageError(Exception):
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"""An Exception raised during verity image building."""
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def __init__(self, message):
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Exception.__init__(self, message)
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def GetVerityFECSize(partition_size):
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cmd = ["fec", "-s", str(partition_size)]
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output = common.RunAndCheckOutput(cmd, verbose=False)
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return int(output)
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def GetVerityTreeSize(partition_size):
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cmd = ["build_verity_tree", "-s", str(partition_size)]
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output = common.RunAndCheckOutput(cmd, verbose=False)
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return int(output)
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def GetVerityMetadataSize(partition_size):
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cmd = ["build_verity_metadata.py", "size", str(partition_size)]
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output = common.RunAndCheckOutput(cmd, verbose=False)
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return int(output)
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def GetVeritySize(partition_size, fec_supported):
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verity_tree_size = GetVerityTreeSize(partition_size)
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verity_metadata_size = GetVerityMetadataSize(partition_size)
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verity_size = verity_tree_size + verity_metadata_size
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if fec_supported:
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fec_size = GetVerityFECSize(partition_size + verity_size)
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return verity_size + fec_size
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return verity_size
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def GetSimgSize(image_file):
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simg = sparse_img.SparseImage(image_file, build_map=False)
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return simg.blocksize * simg.total_blocks
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def ZeroPadSimg(image_file, pad_size):
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blocks = pad_size // BLOCK_SIZE
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logger.info("Padding %d blocks (%d bytes)", blocks, pad_size)
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simg = sparse_img.SparseImage(image_file, mode="r+b", build_map=False)
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simg.AppendFillChunk(0, blocks)
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def AdjustPartitionSizeForVerity(partition_size, fec_supported):
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"""Modifies the provided partition size to account for the verity metadata.
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This information is used to size the created image appropriately.
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Args:
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partition_size: the size of the partition to be verified.
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Returns:
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A tuple of the size of the partition adjusted for verity metadata, and
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the size of verity metadata.
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"""
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key = "%d %d" % (partition_size, fec_supported)
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if key in AdjustPartitionSizeForVerity.results:
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return AdjustPartitionSizeForVerity.results[key]
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hi = partition_size
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if hi % BLOCK_SIZE != 0:
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hi = (hi // BLOCK_SIZE) * BLOCK_SIZE
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# verity tree and fec sizes depend on the partition size, which
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# means this estimate is always going to be unnecessarily small
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verity_size = GetVeritySize(hi, fec_supported)
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lo = partition_size - verity_size
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result = lo
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# do a binary search for the optimal size
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while lo < hi:
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i = ((lo + hi) // (2 * BLOCK_SIZE)) * BLOCK_SIZE
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v = GetVeritySize(i, fec_supported)
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if i + v <= partition_size:
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if result < i:
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result = i
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verity_size = v
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lo = i + BLOCK_SIZE
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else:
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hi = i
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logger.info(
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"Adjusted partition size for verity, partition_size: %s, verity_size: %s",
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result, verity_size)
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AdjustPartitionSizeForVerity.results[key] = (result, verity_size)
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return (result, verity_size)
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AdjustPartitionSizeForVerity.results = {}
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def BuildVerityFEC(sparse_image_path, verity_path, verity_fec_path,
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padding_size):
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cmd = ["fec", "-e", "-p", str(padding_size), sparse_image_path,
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verity_path, verity_fec_path]
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common.RunAndCheckOutput(cmd)
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def BuildVerityTree(sparse_image_path, verity_image_path):
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cmd = ["build_verity_tree", "-A", FIXED_SALT, sparse_image_path,
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verity_image_path]
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output = common.RunAndCheckOutput(cmd)
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root, salt = output.split()
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return root, salt
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def BuildVerityMetadata(image_size, verity_metadata_path, root_hash, salt,
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block_device, signer_path, key, signer_args,
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verity_disable):
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cmd = ["build_verity_metadata.py", "build", str(image_size),
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verity_metadata_path, root_hash, salt, block_device, signer_path, key]
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if signer_args:
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cmd.append("--signer_args=\"%s\"" % (' '.join(signer_args),))
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if verity_disable:
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cmd.append("--verity_disable")
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common.RunAndCheckOutput(cmd)
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def Append2Simg(sparse_image_path, unsparse_image_path, error_message):
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"""Appends the unsparse image to the given sparse image.
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Args:
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sparse_image_path: the path to the (sparse) image
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unsparse_image_path: the path to the (unsparse) image
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Raises:
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BuildVerityImageError: On error.
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"""
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cmd = ["append2simg", sparse_image_path, unsparse_image_path]
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try:
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common.RunAndCheckOutput(cmd)
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except:
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logger.exception(error_message)
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raise BuildVerityImageError(error_message)
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def Append(target, file_to_append, error_message):
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"""Appends file_to_append to target.
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Raises:
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BuildVerityImageError: On error.
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"""
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try:
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with open(target, "a") as out_file, open(file_to_append, "r") as input_file:
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for line in input_file:
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out_file.write(line)
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except IOError:
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logger.exception(error_message)
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raise BuildVerityImageError(error_message)
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def BuildVerifiedImage(data_image_path, verity_image_path,
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verity_metadata_path, verity_fec_path,
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padding_size, fec_supported):
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Append(
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verity_image_path, verity_metadata_path,
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"Could not append verity metadata!")
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if fec_supported:
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# Build FEC for the entire partition, including metadata.
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BuildVerityFEC(
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data_image_path, verity_image_path, verity_fec_path, padding_size)
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Append(verity_image_path, verity_fec_path, "Could not append FEC!")
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Append2Simg(
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data_image_path, verity_image_path, "Could not append verity data!")
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def MakeVerityEnabledImage(out_file, fec_supported, prop_dict):
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"""Creates an image that is verifiable using dm-verity.
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Args:
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out_file: the location to write the verifiable image at
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prop_dict: a dictionary of properties required for image creation and
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verification
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Raises:
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AssertionError: On invalid partition sizes.
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"""
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# get properties
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image_size = int(prop_dict["image_size"])
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block_dev = prop_dict["verity_block_device"]
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signer_key = prop_dict["verity_key"] + ".pk8"
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if OPTIONS.verity_signer_path is not None:
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signer_path = OPTIONS.verity_signer_path
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else:
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signer_path = prop_dict["verity_signer_cmd"]
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signer_args = OPTIONS.verity_signer_args
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tempdir_name = common.MakeTempDir(suffix="_verity_images")
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# Get partial image paths.
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verity_image_path = os.path.join(tempdir_name, "verity.img")
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verity_metadata_path = os.path.join(tempdir_name, "verity_metadata.img")
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verity_fec_path = os.path.join(tempdir_name, "verity_fec.img")
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# Build the verity tree and get the root hash and salt.
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root_hash, salt = BuildVerityTree(out_file, verity_image_path)
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# Build the metadata blocks.
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verity_disable = "verity_disable" in prop_dict
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BuildVerityMetadata(
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image_size, verity_metadata_path, root_hash, salt, block_dev, signer_path,
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signer_key, signer_args, verity_disable)
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# Build the full verified image.
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partition_size = int(prop_dict["partition_size"])
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verity_size = int(prop_dict["verity_size"])
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padding_size = partition_size - image_size - verity_size
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assert padding_size >= 0
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BuildVerifiedImage(
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out_file, verity_image_path, verity_metadata_path, verity_fec_path,
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padding_size, fec_supported)
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def AVBCalcMaxImageSize(avbtool, footer_type, partition_size, additional_args):
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"""Calculates max image size for a given partition size.
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Args:
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avbtool: String with path to avbtool.
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footer_type: 'hash' or 'hashtree' for generating footer.
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partition_size: The size of the partition in question.
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additional_args: Additional arguments to pass to "avbtool add_hash_footer"
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or "avbtool add_hashtree_footer".
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Returns:
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The maximum image size.
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Raises:
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BuildVerityImageError: On invalid image size.
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"""
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cmd = [avbtool, "add_%s_footer" % footer_type,
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"--partition_size", str(partition_size), "--calc_max_image_size"]
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cmd.extend(shlex.split(additional_args))
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output = common.RunAndCheckOutput(cmd)
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image_size = int(output)
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if image_size <= 0:
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raise BuildVerityImageError(
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"Invalid max image size: {}".format(output))
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return image_size
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def AVBCalcMinPartitionSize(image_size, size_calculator):
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"""Calculates min partition size for a given image size.
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Args:
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image_size: The size of the image in question.
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size_calculator: The function to calculate max image size
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for a given partition size.
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Returns:
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The minimum partition size required to accommodate the image size.
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"""
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# Use image size as partition size to approximate final partition size.
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image_ratio = size_calculator(image_size) / float(image_size)
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# Prepare a binary search for the optimal partition size.
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lo = int(image_size / image_ratio) // BLOCK_SIZE * BLOCK_SIZE - BLOCK_SIZE
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# Ensure lo is small enough: max_image_size should <= image_size.
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delta = BLOCK_SIZE
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max_image_size = size_calculator(lo)
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while max_image_size > image_size:
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image_ratio = max_image_size / float(lo)
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lo = int(image_size / image_ratio) // BLOCK_SIZE * BLOCK_SIZE - delta
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delta *= 2
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max_image_size = size_calculator(lo)
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hi = lo + BLOCK_SIZE
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# Ensure hi is large enough: max_image_size should >= image_size.
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delta = BLOCK_SIZE
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max_image_size = size_calculator(hi)
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while max_image_size < image_size:
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image_ratio = max_image_size / float(hi)
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hi = int(image_size / image_ratio) // BLOCK_SIZE * BLOCK_SIZE + delta
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delta *= 2
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max_image_size = size_calculator(hi)
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partition_size = hi
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# Start to binary search.
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while lo < hi:
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mid = ((lo + hi) // (2 * BLOCK_SIZE)) * BLOCK_SIZE
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max_image_size = size_calculator(mid)
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if max_image_size >= image_size: # if mid can accommodate image_size
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if mid < partition_size: # if a smaller partition size is found
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partition_size = mid
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hi = mid
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else:
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lo = mid + BLOCK_SIZE
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logger.info(
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"AVBCalcMinPartitionSize(%d): partition_size: %d.",
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image_size, partition_size)
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return partition_size
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def AVBAddFooter(image_path, avbtool, footer_type, partition_size,
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partition_name, key_path, algorithm, salt,
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additional_args):
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"""Adds dm-verity hashtree and AVB metadata to an image.
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Args:
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image_path: Path to image to modify.
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avbtool: String with path to avbtool.
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footer_type: 'hash' or 'hashtree' for generating footer.
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partition_size: The size of the partition in question.
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partition_name: The name of the partition - will be embedded in metadata.
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key_path: Path to key to use or None.
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algorithm: Name of algorithm to use or None.
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salt: The salt to use (a hexadecimal string) or None.
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additional_args: Additional arguments to pass to "avbtool add_hash_footer"
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or "avbtool add_hashtree_footer".
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"""
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cmd = [avbtool, "add_%s_footer" % footer_type,
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"--partition_size", partition_size,
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"--partition_name", partition_name,
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"--image", image_path]
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if key_path and algorithm:
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cmd.extend(["--key", key_path, "--algorithm", algorithm])
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if salt:
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cmd.extend(["--salt", salt])
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cmd.extend(shlex.split(additional_args))
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common.RunAndCheckOutput(cmd)
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class HashtreeInfoGenerationError(Exception):
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"""An Exception raised during hashtree info generation."""
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def __init__(self, message):
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Exception.__init__(self, message)
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class HashtreeInfo(object):
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def __init__(self):
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self.hashtree_range = None
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self.filesystem_range = None
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self.hash_algorithm = None
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self.salt = None
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self.root_hash = None
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def CreateHashtreeInfoGenerator(partition_name, block_size, info_dict):
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generator = None
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if (info_dict.get("verity") == "true" and
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info_dict.get("{}_verity_block_device".format(partition_name))):
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partition_size = info_dict["{}_size".format(partition_name)]
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fec_supported = info_dict.get("verity_fec") == "true"
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generator = VerifiedBootVersion1HashtreeInfoGenerator(
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partition_size, block_size, fec_supported)
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return generator
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class HashtreeInfoGenerator(object):
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def Generate(self, image):
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raise NotImplementedError
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def DecomposeSparseImage(self, image):
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raise NotImplementedError
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def ValidateHashtree(self):
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raise NotImplementedError
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class VerifiedBootVersion1HashtreeInfoGenerator(HashtreeInfoGenerator):
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"""A class that parses the metadata of hashtree for a given partition."""
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def __init__(self, partition_size, block_size, fec_supported):
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"""Initialize VerityTreeInfo with the sparse image and input property.
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Arguments:
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partition_size: The whole size in bytes of a partition, including the
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filesystem size, padding size, and verity size.
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block_size: Expected size in bytes of each block for the sparse image.
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fec_supported: True if the verity section contains fec data.
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"""
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self.block_size = block_size
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self.partition_size = partition_size
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self.fec_supported = fec_supported
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self.image = None
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self.filesystem_size = None
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self.hashtree_size = None
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self.metadata_size = None
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self.hashtree_info = HashtreeInfo()
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def DecomposeSparseImage(self, image):
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"""Calculate the verity size based on the size of the input image.
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Since we already know the structure of a verity enabled image to be:
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[filesystem, verity_hashtree, verity_metadata, fec_data]. We can then
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calculate the size and offset of each section.
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"""
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self.image = image
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assert self.block_size == image.blocksize
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assert self.partition_size == image.total_blocks * self.block_size, \
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"partition size {} doesn't match with the calculated image size." \
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" total_blocks: {}".format(self.partition_size, image.total_blocks)
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adjusted_size, _ = AdjustPartitionSizeForVerity(
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self.partition_size, self.fec_supported)
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assert adjusted_size % self.block_size == 0
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verity_tree_size = GetVerityTreeSize(adjusted_size)
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assert verity_tree_size % self.block_size == 0
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metadata_size = GetVerityMetadataSize(adjusted_size)
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assert metadata_size % self.block_size == 0
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self.filesystem_size = adjusted_size
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self.hashtree_size = verity_tree_size
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self.metadata_size = metadata_size
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self.hashtree_info.filesystem_range = RangeSet(
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data=[0, adjusted_size / self.block_size])
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self.hashtree_info.hashtree_range = RangeSet(
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data=[adjusted_size / self.block_size,
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(adjusted_size + verity_tree_size) / self.block_size])
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def _ParseHashtreeMetadata(self):
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"""Parses the hash_algorithm, root_hash, salt from the metadata block."""
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metadata_start = self.filesystem_size + self.hashtree_size
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metadata_range = RangeSet(
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data=[metadata_start / self.block_size,
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(metadata_start + self.metadata_size) / self.block_size])
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meta_data = ''.join(self.image.ReadRangeSet(metadata_range))
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# More info about the metadata structure available in:
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# system/extras/verity/build_verity_metadata.py
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META_HEADER_SIZE = 268
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header_bin = meta_data[0:META_HEADER_SIZE]
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header = struct.unpack("II256sI", header_bin)
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# header: magic_number, version, signature, table_len
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assert header[0] == 0xb001b001, header[0]
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table_len = header[3]
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verity_table = meta_data[META_HEADER_SIZE: META_HEADER_SIZE + table_len]
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table_entries = verity_table.rstrip().split()
|
|
|
|
# Expected verity table format: "1 block_device block_device block_size
|
|
# block_size data_blocks data_blocks hash_algorithm root_hash salt"
|
|
assert len(table_entries) == 10, "Unexpected verity table size {}".format(
|
|
len(table_entries))
|
|
assert (int(table_entries[3]) == self.block_size and
|
|
int(table_entries[4]) == self.block_size)
|
|
assert (int(table_entries[5]) * self.block_size == self.filesystem_size and
|
|
int(table_entries[6]) * self.block_size == self.filesystem_size)
|
|
|
|
self.hashtree_info.hash_algorithm = table_entries[7]
|
|
self.hashtree_info.root_hash = table_entries[8]
|
|
self.hashtree_info.salt = table_entries[9]
|
|
|
|
def ValidateHashtree(self):
|
|
"""Checks that we can reconstruct the verity hash tree."""
|
|
|
|
# Writes the file system section to a temp file; and calls the executable
|
|
# build_verity_tree to construct the hash tree.
|
|
adjusted_partition = common.MakeTempFile(prefix="adjusted_partition")
|
|
with open(adjusted_partition, "wb") as fd:
|
|
self.image.WriteRangeDataToFd(self.hashtree_info.filesystem_range, fd)
|
|
|
|
generated_verity_tree = common.MakeTempFile(prefix="verity")
|
|
root_hash, salt = BuildVerityTree(adjusted_partition, generated_verity_tree)
|
|
|
|
# The salt should be always identical, as we use fixed value.
|
|
assert salt == self.hashtree_info.salt, \
|
|
"Calculated salt {} doesn't match the one in metadata {}".format(
|
|
salt, self.hashtree_info.salt)
|
|
|
|
if root_hash != self.hashtree_info.root_hash:
|
|
logger.warning(
|
|
"Calculated root hash %s doesn't match the one in metadata %s",
|
|
root_hash, self.hashtree_info.root_hash)
|
|
return False
|
|
|
|
# Reads the generated hash tree and checks if it has the exact same bytes
|
|
# as the one in the sparse image.
|
|
with open(generated_verity_tree, "rb") as fd:
|
|
return fd.read() == ''.join(self.image.ReadRangeSet(
|
|
self.hashtree_info.hashtree_range))
|
|
|
|
def Generate(self, image):
|
|
"""Parses and validates the hashtree info in a sparse image.
|
|
|
|
Returns:
|
|
hashtree_info: The information needed to reconstruct the hashtree.
|
|
|
|
Raises:
|
|
HashtreeInfoGenerationError: If we fail to generate the exact bytes of
|
|
the hashtree.
|
|
"""
|
|
|
|
self.DecomposeSparseImage(image)
|
|
self._ParseHashtreeMetadata()
|
|
|
|
if not self.ValidateHashtree():
|
|
raise HashtreeInfoGenerationError("Failed to reconstruct the verity tree")
|
|
|
|
return self.hashtree_info
|