releasetools: Move verity related functions into verity_utils.py.

This prepares for upcoming changes that refactor verity-related
functions into classes.

This CL makes minimal changes to the moved functions, by creating a new
BuildVerityImageError class in verity_utils.py replacing the former
BuildImageError that's specific to build_image.py. As part of the
change, it also moves the tests for AVBCalcMinPartitionSize into
test_verity_utils.py.

Test: python -m unittest test_verity_utils
Test: `m dist` with aosp_marlin-userdebug (Verified Boot 1.0)
Test: `m dist` with aosp_taimen-userdebug (Verified Boot 2.0)
Change-Id: I19b52714d8980705ea1f9484ac03eb0af9483240
This commit is contained in:
Tao Bao 2018-10-11 14:08:45 -07:00
parent e95680a60f
commit 71197515bb
5 changed files with 423 additions and 409 deletions

View File

@ -29,18 +29,14 @@ from __future__ import print_function
import os
import os.path
import re
import shlex
import shutil
import sys
import common
import sparse_img
import verity_utils
OPTIONS = common.OPTIONS
FIXED_SALT = "aee087a5be3b982978c923f566a94613496b417f2af592639bc80d141e34dfe7"
BLOCK_SIZE = 4096
BLOCK_SIZE = common.BLOCK_SIZE
BYTES_IN_MB = 1024 * 1024
@ -51,34 +47,6 @@ class BuildImageError(Exception):
Exception.__init__(self, message)
def GetVerityFECSize(partition_size):
cmd = ["fec", "-s", str(partition_size)]
output = common.RunAndCheckOutput(cmd, verbose=False)
return int(output)
def GetVerityTreeSize(partition_size):
cmd = ["build_verity_tree", "-s", str(partition_size)]
output = common.RunAndCheckOutput(cmd, verbose=False)
return int(output)
def GetVerityMetadataSize(partition_size):
cmd = ["build_verity_metadata.py", "size", str(partition_size)]
output = common.RunAndCheckOutput(cmd, verbose=False)
return int(output)
def GetVeritySize(partition_size, fec_supported):
verity_tree_size = GetVerityTreeSize(partition_size)
verity_metadata_size = GetVerityMetadataSize(partition_size)
verity_size = verity_tree_size + verity_metadata_size
if fec_supported:
fec_size = GetVerityFECSize(partition_size + verity_size)
return verity_size + fec_size
return verity_size
def GetDiskUsage(path):
"""Returns the number of bytes that "path" occupies on host.
@ -102,258 +70,6 @@ def GetDiskUsage(path):
return int(output.split()[0]) * 512
def GetSimgSize(image_file):
simg = sparse_img.SparseImage(image_file, build_map=False)
return simg.blocksize * simg.total_blocks
def ZeroPadSimg(image_file, pad_size):
blocks = pad_size // BLOCK_SIZE
print("Padding %d blocks (%d bytes)" % (blocks, pad_size))
simg = sparse_img.SparseImage(image_file, mode="r+b", build_map=False)
simg.AppendFillChunk(0, blocks)
def AVBCalcMaxImageSize(avbtool, footer_type, partition_size, additional_args):
"""Calculates max image size for a given partition size.
Args:
avbtool: String with path to avbtool.
footer_type: 'hash' or 'hashtree' for generating footer.
partition_size: The size of the partition in question.
additional_args: Additional arguments to pass to "avbtool add_hash_footer"
or "avbtool add_hashtree_footer".
Returns:
The maximum image size.
Raises:
BuildImageError: On invalid image size.
"""
cmd = [avbtool, "add_%s_footer" % footer_type,
"--partition_size", str(partition_size), "--calc_max_image_size"]
cmd.extend(shlex.split(additional_args))
output = common.RunAndCheckOutput(cmd)
image_size = int(output)
if image_size <= 0:
raise BuildImageError(
"Invalid max image size: {}".format(output))
return image_size
def AVBCalcMinPartitionSize(image_size, size_calculator):
"""Calculates min partition size for a given image size.
Args:
image_size: The size of the image in question.
size_calculator: The function to calculate max image size
for a given partition size.
Returns:
The minimum partition size required to accommodate the image size.
"""
# Use image size as partition size to approximate final partition size.
image_ratio = size_calculator(image_size) / float(image_size)
# Prepare a binary search for the optimal partition size.
lo = int(image_size / image_ratio) // BLOCK_SIZE * BLOCK_SIZE - BLOCK_SIZE
# Ensure lo is small enough: max_image_size should <= image_size.
delta = BLOCK_SIZE
max_image_size = size_calculator(lo)
while max_image_size > image_size:
image_ratio = max_image_size / float(lo)
lo = int(image_size / image_ratio) // BLOCK_SIZE * BLOCK_SIZE - delta
delta *= 2
max_image_size = size_calculator(lo)
hi = lo + BLOCK_SIZE
# Ensure hi is large enough: max_image_size should >= image_size.
delta = BLOCK_SIZE
max_image_size = size_calculator(hi)
while max_image_size < image_size:
image_ratio = max_image_size / float(hi)
hi = int(image_size / image_ratio) // BLOCK_SIZE * BLOCK_SIZE + delta
delta *= 2
max_image_size = size_calculator(hi)
partition_size = hi
# Start to binary search.
while lo < hi:
mid = ((lo + hi) // (2 * BLOCK_SIZE)) * BLOCK_SIZE
max_image_size = size_calculator(mid)
if max_image_size >= image_size: # if mid can accommodate image_size
if mid < partition_size: # if a smaller partition size is found
partition_size = mid
hi = mid
else:
lo = mid + BLOCK_SIZE
if OPTIONS.verbose:
print("AVBCalcMinPartitionSize({}): partition_size: {}.".format(
image_size, partition_size))
return partition_size
def AVBAddFooter(image_path, avbtool, footer_type, partition_size,
partition_name, key_path, algorithm, salt,
additional_args):
"""Adds dm-verity hashtree and AVB metadata to an image.
Args:
image_path: Path to image to modify.
avbtool: String with path to avbtool.
footer_type: 'hash' or 'hashtree' for generating footer.
partition_size: The size of the partition in question.
partition_name: The name of the partition - will be embedded in metadata.
key_path: Path to key to use or None.
algorithm: Name of algorithm to use or None.
salt: The salt to use (a hexadecimal string) or None.
additional_args: Additional arguments to pass to "avbtool add_hash_footer"
or "avbtool add_hashtree_footer".
"""
cmd = [avbtool, "add_%s_footer" % footer_type,
"--partition_size", partition_size,
"--partition_name", partition_name,
"--image", image_path]
if key_path and algorithm:
cmd.extend(["--key", key_path, "--algorithm", algorithm])
if salt:
cmd.extend(["--salt", salt])
cmd.extend(shlex.split(additional_args))
common.RunAndCheckOutput(cmd)
def AdjustPartitionSizeForVerity(partition_size, fec_supported):
"""Modifies the provided partition size to account for the verity metadata.
This information is used to size the created image appropriately.
Args:
partition_size: the size of the partition to be verified.
Returns:
A tuple of the size of the partition adjusted for verity metadata, and
the size of verity metadata.
"""
key = "%d %d" % (partition_size, fec_supported)
if key in AdjustPartitionSizeForVerity.results:
return AdjustPartitionSizeForVerity.results[key]
hi = partition_size
if hi % BLOCK_SIZE != 0:
hi = (hi // BLOCK_SIZE) * BLOCK_SIZE
# verity tree and fec sizes depend on the partition size, which
# means this estimate is always going to be unnecessarily small
verity_size = GetVeritySize(hi, fec_supported)
lo = partition_size - verity_size
result = lo
# do a binary search for the optimal size
while lo < hi:
i = ((lo + hi) // (2 * BLOCK_SIZE)) * BLOCK_SIZE
v = GetVeritySize(i, fec_supported)
if i + v <= partition_size:
if result < i:
result = i
verity_size = v
lo = i + BLOCK_SIZE
else:
hi = i
if OPTIONS.verbose:
print("Adjusted partition size for verity, partition_size: {},"
" verity_size: {}".format(result, verity_size))
AdjustPartitionSizeForVerity.results[key] = (result, verity_size)
return (result, verity_size)
AdjustPartitionSizeForVerity.results = {}
def BuildVerityFEC(sparse_image_path, verity_path, verity_fec_path,
padding_size):
cmd = ["fec", "-e", "-p", str(padding_size), sparse_image_path,
verity_path, verity_fec_path]
common.RunAndCheckOutput(cmd)
def BuildVerityTree(sparse_image_path, verity_image_path):
cmd = ["build_verity_tree", "-A", FIXED_SALT, sparse_image_path,
verity_image_path]
output = common.RunAndCheckOutput(cmd)
root, salt = output.split()
return root, salt
def BuildVerityMetadata(image_size, verity_metadata_path, root_hash, salt,
block_device, signer_path, key, signer_args,
verity_disable):
cmd = ["build_verity_metadata.py", "build", str(image_size),
verity_metadata_path, root_hash, salt, block_device, signer_path, key]
if signer_args:
cmd.append("--signer_args=\"%s\"" % (' '.join(signer_args),))
if verity_disable:
cmd.append("--verity_disable")
common.RunAndCheckOutput(cmd)
def Append2Simg(sparse_image_path, unsparse_image_path, error_message):
"""Appends the unsparse image to the given sparse image.
Args:
sparse_image_path: the path to the (sparse) image
unsparse_image_path: the path to the (unsparse) image
Raises:
BuildImageError: On error.
"""
cmd = ["append2simg", sparse_image_path, unsparse_image_path]
try:
common.RunAndCheckOutput(cmd)
except:
raise BuildImageError(error_message)
def Append(target, file_to_append, error_message):
"""Appends file_to_append to target.
Raises:
BuildImageError: On error.
"""
try:
with open(target, "a") as out_file, open(file_to_append, "r") as input_file:
for line in input_file:
out_file.write(line)
except IOError:
raise BuildImageError(error_message)
def BuildVerifiedImage(data_image_path, verity_image_path,
verity_metadata_path, verity_fec_path,
padding_size, fec_supported):
Append(
verity_image_path, verity_metadata_path,
"Could not append verity metadata!")
if fec_supported:
# Build FEC for the entire partition, including metadata.
BuildVerityFEC(
data_image_path, verity_image_path, verity_fec_path, padding_size)
Append(verity_image_path, verity_fec_path, "Could not append FEC!")
Append2Simg(
data_image_path, verity_image_path, "Could not append verity data!")
def UnsparseImage(sparse_image_path, replace=True):
img_dir = os.path.dirname(sparse_image_path)
unsparse_image_path = "unsparse_" + os.path.basename(sparse_image_path)
@ -372,56 +88,6 @@ def UnsparseImage(sparse_image_path, replace=True):
return unsparse_image_path
def MakeVerityEnabledImage(out_file, fec_supported, prop_dict):
"""Creates an image that is verifiable using dm-verity.
Args:
out_file: the location to write the verifiable image at
prop_dict: a dictionary of properties required for image creation and
verification
Raises:
AssertionError: On invalid partition sizes.
BuildImageError: On other errors.
"""
# get properties
image_size = int(prop_dict["image_size"])
block_dev = prop_dict["verity_block_device"]
signer_key = prop_dict["verity_key"] + ".pk8"
if OPTIONS.verity_signer_path is not None:
signer_path = OPTIONS.verity_signer_path
else:
signer_path = prop_dict["verity_signer_cmd"]
signer_args = OPTIONS.verity_signer_args
tempdir_name = common.MakeTempDir(suffix="_verity_images")
# Get partial image paths.
verity_image_path = os.path.join(tempdir_name, "verity.img")
verity_metadata_path = os.path.join(tempdir_name, "verity_metadata.img")
verity_fec_path = os.path.join(tempdir_name, "verity_fec.img")
# Build the verity tree and get the root hash and salt.
root_hash, salt = BuildVerityTree(out_file, verity_image_path)
# Build the metadata blocks.
verity_disable = "verity_disable" in prop_dict
BuildVerityMetadata(
image_size, verity_metadata_path, root_hash, salt, block_dev, signer_path,
signer_key, signer_args, verity_disable)
# Build the full verified image.
partition_size = int(prop_dict["partition_size"])
verity_size = int(prop_dict["verity_size"])
padding_size = partition_size - image_size - verity_size
assert padding_size >= 0
BuildVerifiedImage(
out_file, verity_image_path, verity_metadata_path, verity_fec_path,
padding_size, fec_supported)
def ConvertBlockMapToBaseFs(block_map_file):
base_fs_file = common.MakeTempFile(prefix="script_gen_", suffix=".base_fs")
convert_command = ["blk_alloc_to_base_fs", block_map_file, base_fs_file]
@ -570,9 +236,9 @@ def BuildImage(in_dir, prop_dict, out_file, target_out=None):
# Adjust partition_size to add more space for AVB footer, to prevent
# it from consuming partition_reserved_size.
if avb_footer_type:
size = AVBCalcMinPartitionSize(
size = verity_utils.AVBCalcMinPartitionSize(
size,
lambda x: AVBCalcMaxImageSize(
lambda x: verity_utils.AVBCalcMaxImageSize(
avbtool, avb_footer_type, x, avb_signing_args))
prop_dict["partition_size"] = str(size)
if OPTIONS.verbose:
@ -583,7 +249,7 @@ def BuildImage(in_dir, prop_dict, out_file, target_out=None):
# Adjust the image size to make room for the hashes if this is to be verified.
if verity_supported and is_verity_partition:
partition_size = int(prop_dict.get("partition_size"))
image_size, verity_size = AdjustPartitionSizeForVerity(
image_size, verity_size = verity_utils.AdjustPartitionSizeForVerity(
partition_size, verity_fec_supported)
prop_dict["image_size"] = str(image_size)
prop_dict["verity_size"] = str(verity_size)
@ -592,7 +258,7 @@ def BuildImage(in_dir, prop_dict, out_file, target_out=None):
if avb_footer_type:
partition_size = prop_dict["partition_size"]
# avb_add_hash_footer_args or avb_add_hashtree_footer_args.
max_image_size = AVBCalcMaxImageSize(
max_image_size = verity_utils.AVBCalcMaxImageSize(
avbtool, avb_footer_type, partition_size, avb_signing_args)
prop_dict["image_size"] = str(max_image_size)
@ -709,17 +375,18 @@ def BuildImage(in_dir, prop_dict, out_file, target_out=None):
if not fs_spans_partition:
mount_point = prop_dict.get("mount_point")
image_size = int(prop_dict["image_size"])
sparse_image_size = GetSimgSize(out_file)
sparse_image_size = verity_utils.GetSimgSize(out_file)
if sparse_image_size > image_size:
raise BuildImageError(
"Error: {} image size of {} is larger than partition size of "
"{}".format(mount_point, sparse_image_size, image_size))
if verity_supported and is_verity_partition:
ZeroPadSimg(out_file, image_size - sparse_image_size)
verity_utils.ZeroPadSimg(out_file, image_size - sparse_image_size)
# Create the verified image if this is to be verified.
if verity_supported and is_verity_partition:
MakeVerityEnabledImage(out_file, verity_fec_supported, prop_dict)
verity_utils.MakeVerityEnabledImage(
out_file, verity_fec_supported, prop_dict)
# Add AVB HASH or HASHTREE footer (metadata).
if avb_footer_type:
@ -729,7 +396,7 @@ def BuildImage(in_dir, prop_dict, out_file, target_out=None):
key_path = prop_dict.get("avb_key_path")
algorithm = prop_dict.get("avb_algorithm")
salt = prop_dict.get("avb_salt")
AVBAddFooter(
verity_utils.AVBAddFooter(
out_file, avbtool, avb_footer_type, partition_size, partition_name,
key_path, algorithm, salt, avb_signing_args)

View File

@ -73,6 +73,9 @@ class Options(object):
OPTIONS = Options()
# The block size that's used across the releasetools scripts.
BLOCK_SIZE = 4096
# Values for "certificate" in apkcerts that mean special things.
SPECIAL_CERT_STRINGS = ("PRESIGNED", "EXTERNAL")

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@ -15,14 +15,11 @@
#
import filecmp
import math
import os.path
import random
import common
from build_image import (
AVBCalcMinPartitionSize, BLOCK_SIZE, BuildImageError, CheckHeadroom,
SetUpInDirAndFsConfig)
BuildImageError, CheckHeadroom, SetUpInDirAndFsConfig)
from test_utils import ReleaseToolsTestCase
@ -32,13 +29,6 @@ class BuildImageTest(ReleaseToolsTestCase):
EXT4FS_OUTPUT = (
"Created filesystem with 2777/129024 inodes and 515099/516099 blocks")
def setUp(self):
# To test AVBCalcMinPartitionSize(), by using 200MB to 2GB image size.
# - 51200 = 200MB * 1024 * 1024 / 4096
# - 524288 = 2GB * 1024 * 1024 * 1024 / 4096
self._image_sizes = [BLOCK_SIZE * random.randint(51200, 524288) + offset
for offset in range(BLOCK_SIZE)]
def test_CheckHeadroom_SizeUnderLimit(self):
# Required headroom: 1000 blocks.
prop_dict = {
@ -186,51 +176,3 @@ class BuildImageTest(ReleaseToolsTestCase):
self.assertIn('fs-config-system\n', fs_config_data)
self.assertIn('fs-config-root\n', fs_config_data)
self.assertEqual('/', prop_dict['mount_point'])
def test_AVBCalcMinPartitionSize_LinearFooterSize(self):
"""Tests with footer size which is linear to partition size."""
for image_size in self._image_sizes:
for ratio in 0.95, 0.56, 0.22:
expected_size = common.RoundUpTo4K(int(math.ceil(image_size / ratio)))
self.assertEqual(
expected_size,
AVBCalcMinPartitionSize(image_size, lambda x: int(x * ratio)))
def test_AVBCalcMinPartitionSize_SlowerGrowthFooterSize(self):
"""Tests with footer size which grows slower than partition size."""
def _SizeCalculator(partition_size):
"""Footer size is the power of 0.95 of partition size."""
# Minus footer size to return max image size.
return partition_size - int(math.pow(partition_size, 0.95))
for image_size in self._image_sizes:
min_partition_size = AVBCalcMinPartitionSize(image_size, _SizeCalculator)
# Checks min_partition_size can accommodate image_size.
self.assertGreaterEqual(
_SizeCalculator(min_partition_size),
image_size)
# Checks min_partition_size (round to BLOCK_SIZE) is the minimum.
self.assertLess(
_SizeCalculator(min_partition_size - BLOCK_SIZE),
image_size)
def test_AVBCalcMinPartitionSize_FasterGrowthFooterSize(self):
"""Tests with footer size which grows faster than partition size."""
def _SizeCalculator(partition_size):
"""Max image size is the power of 0.95 of partition size."""
# Max image size grows less than partition size, which means
# footer size grows faster than partition size.
return int(math.pow(partition_size, 0.95))
for image_size in self._image_sizes:
min_partition_size = AVBCalcMinPartitionSize(image_size, _SizeCalculator)
# Checks min_partition_size can accommodate image_size.
self.assertGreaterEqual(
_SizeCalculator(min_partition_size),
image_size)
# Checks min_partition_size (round to BLOCK_SIZE) is the minimum.
self.assertLess(
_SizeCalculator(min_partition_size - BLOCK_SIZE),
image_size)

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@ -16,15 +16,17 @@
"""Unittests for verity_utils.py."""
import math
import os.path
import random
import build_image
import common
import sparse_img
from rangelib import RangeSet
from test_utils import get_testdata_dir, ReleaseToolsTestCase
from verity_utils import (
CreateHashtreeInfoGenerator, HashtreeInfo,
AdjustPartitionSizeForVerity, AVBCalcMinPartitionSize, BLOCK_SIZE,
CreateHashtreeInfoGenerator, HashtreeInfo, MakeVerityEnabledImage,
VerifiedBootVersion1HashtreeInfoGenerator)
@ -62,7 +64,7 @@ class VerifiedBootVersion1HashtreeInfoGeneratorTest(ReleaseToolsTestCase):
def _generate_image(self):
partition_size = 1024 * 1024
adjusted_size, verity_size = build_image.AdjustPartitionSizeForVerity(
adjusted_size, verity_size = AdjustPartitionSizeForVerity(
partition_size, True)
raw_image = ""
@ -80,7 +82,7 @@ class VerifiedBootVersion1HashtreeInfoGeneratorTest(ReleaseToolsTestCase):
'verity_signer_cmd': 'verity_signer',
'verity_size': str(verity_size),
}
build_image.MakeVerityEnabledImage(output_file, True, prop_dict)
MakeVerityEnabledImage(output_file, True, prop_dict)
return output_file
@ -159,3 +161,62 @@ class VerifiedBootVersion1HashtreeInfoGeneratorTest(ReleaseToolsTestCase):
self.assertEqual(self.hash_algorithm, info.hash_algorithm)
self.assertEqual(self.fixed_salt, info.salt)
self.assertEqual(self.expected_root_hash, info.root_hash)
class VerityUtilsTest(ReleaseToolsTestCase):
def setUp(self):
# To test AVBCalcMinPartitionSize(), by using 200MB to 2GB image size.
# - 51200 = 200MB * 1024 * 1024 / 4096
# - 524288 = 2GB * 1024 * 1024 * 1024 / 4096
self._image_sizes = [BLOCK_SIZE * random.randint(51200, 524288) + offset
for offset in range(BLOCK_SIZE)]
def test_AVBCalcMinPartitionSize_LinearFooterSize(self):
"""Tests with footer size which is linear to partition size."""
for image_size in self._image_sizes:
for ratio in 0.95, 0.56, 0.22:
expected_size = common.RoundUpTo4K(int(math.ceil(image_size / ratio)))
self.assertEqual(
expected_size,
AVBCalcMinPartitionSize(
image_size, lambda x, ratio=ratio: int(x * ratio)))
def test_AVBCalcMinPartitionSize_SlowerGrowthFooterSize(self):
"""Tests with footer size which grows slower than partition size."""
def _SizeCalculator(partition_size):
"""Footer size is the power of 0.95 of partition size."""
# Minus footer size to return max image size.
return partition_size - int(math.pow(partition_size, 0.95))
for image_size in self._image_sizes:
min_partition_size = AVBCalcMinPartitionSize(image_size, _SizeCalculator)
# Checks min_partition_size can accommodate image_size.
self.assertGreaterEqual(
_SizeCalculator(min_partition_size),
image_size)
# Checks min_partition_size (round to BLOCK_SIZE) is the minimum.
self.assertLess(
_SizeCalculator(min_partition_size - BLOCK_SIZE),
image_size)
def test_AVBCalcMinPartitionSize_FasterGrowthFooterSize(self):
"""Tests with footer size which grows faster than partition size."""
def _SizeCalculator(partition_size):
"""Max image size is the power of 0.95 of partition size."""
# Max image size grows less than partition size, which means
# footer size grows faster than partition size.
return int(math.pow(partition_size, 0.95))
for image_size in self._image_sizes:
min_partition_size = AVBCalcMinPartitionSize(image_size, _SizeCalculator)
# Checks min_partition_size can accommodate image_size.
self.assertGreaterEqual(
_SizeCalculator(min_partition_size),
image_size)
# Checks min_partition_size (round to BLOCK_SIZE) is the minimum.
self.assertLess(
_SizeCalculator(min_partition_size - BLOCK_SIZE),
image_size)

View File

@ -16,13 +16,354 @@
from __future__ import print_function
import os.path
import shlex
import struct
import common
from build_image import (AdjustPartitionSizeForVerity, GetVerityTreeSize,
GetVerityMetadataSize, BuildVerityTree)
import sparse_img
from rangelib import RangeSet
OPTIONS = common.OPTIONS
BLOCK_SIZE = common.BLOCK_SIZE
FIXED_SALT = "aee087a5be3b982978c923f566a94613496b417f2af592639bc80d141e34dfe7"
class BuildVerityImageError(Exception):
"""An Exception raised during verity image building."""
def __init__(self, message):
Exception.__init__(self, message)
def GetVerityFECSize(partition_size):
cmd = ["fec", "-s", str(partition_size)]
output = common.RunAndCheckOutput(cmd, verbose=False)
return int(output)
def GetVerityTreeSize(partition_size):
cmd = ["build_verity_tree", "-s", str(partition_size)]
output = common.RunAndCheckOutput(cmd, verbose=False)
return int(output)
def GetVerityMetadataSize(partition_size):
cmd = ["build_verity_metadata.py", "size", str(partition_size)]
output = common.RunAndCheckOutput(cmd, verbose=False)
return int(output)
def GetVeritySize(partition_size, fec_supported):
verity_tree_size = GetVerityTreeSize(partition_size)
verity_metadata_size = GetVerityMetadataSize(partition_size)
verity_size = verity_tree_size + verity_metadata_size
if fec_supported:
fec_size = GetVerityFECSize(partition_size + verity_size)
return verity_size + fec_size
return verity_size
def GetSimgSize(image_file):
simg = sparse_img.SparseImage(image_file, build_map=False)
return simg.blocksize * simg.total_blocks
def ZeroPadSimg(image_file, pad_size):
blocks = pad_size // BLOCK_SIZE
print("Padding %d blocks (%d bytes)" % (blocks, pad_size))
simg = sparse_img.SparseImage(image_file, mode="r+b", build_map=False)
simg.AppendFillChunk(0, blocks)
def AdjustPartitionSizeForVerity(partition_size, fec_supported):
"""Modifies the provided partition size to account for the verity metadata.
This information is used to size the created image appropriately.
Args:
partition_size: the size of the partition to be verified.
Returns:
A tuple of the size of the partition adjusted for verity metadata, and
the size of verity metadata.
"""
key = "%d %d" % (partition_size, fec_supported)
if key in AdjustPartitionSizeForVerity.results:
return AdjustPartitionSizeForVerity.results[key]
hi = partition_size
if hi % BLOCK_SIZE != 0:
hi = (hi // BLOCK_SIZE) * BLOCK_SIZE
# verity tree and fec sizes depend on the partition size, which
# means this estimate is always going to be unnecessarily small
verity_size = GetVeritySize(hi, fec_supported)
lo = partition_size - verity_size
result = lo
# do a binary search for the optimal size
while lo < hi:
i = ((lo + hi) // (2 * BLOCK_SIZE)) * BLOCK_SIZE
v = GetVeritySize(i, fec_supported)
if i + v <= partition_size:
if result < i:
result = i
verity_size = v
lo = i + BLOCK_SIZE
else:
hi = i
if OPTIONS.verbose:
print("Adjusted partition size for verity, partition_size: {},"
" verity_size: {}".format(result, verity_size))
AdjustPartitionSizeForVerity.results[key] = (result, verity_size)
return (result, verity_size)
AdjustPartitionSizeForVerity.results = {}
def BuildVerityFEC(sparse_image_path, verity_path, verity_fec_path,
padding_size):
cmd = ["fec", "-e", "-p", str(padding_size), sparse_image_path,
verity_path, verity_fec_path]
common.RunAndCheckOutput(cmd)
def BuildVerityTree(sparse_image_path, verity_image_path):
cmd = ["build_verity_tree", "-A", FIXED_SALT, sparse_image_path,
verity_image_path]
output = common.RunAndCheckOutput(cmd)
root, salt = output.split()
return root, salt
def BuildVerityMetadata(image_size, verity_metadata_path, root_hash, salt,
block_device, signer_path, key, signer_args,
verity_disable):
cmd = ["build_verity_metadata.py", "build", str(image_size),
verity_metadata_path, root_hash, salt, block_device, signer_path, key]
if signer_args:
cmd.append("--signer_args=\"%s\"" % (' '.join(signer_args),))
if verity_disable:
cmd.append("--verity_disable")
common.RunAndCheckOutput(cmd)
def Append2Simg(sparse_image_path, unsparse_image_path, error_message):
"""Appends the unsparse image to the given sparse image.
Args:
sparse_image_path: the path to the (sparse) image
unsparse_image_path: the path to the (unsparse) image
Raises:
BuildVerityImageError: On error.
"""
cmd = ["append2simg", sparse_image_path, unsparse_image_path]
try:
common.RunAndCheckOutput(cmd)
except:
raise BuildVerityImageError(error_message)
def Append(target, file_to_append, error_message):
"""Appends file_to_append to target.
Raises:
BuildVerityImageError: On error.
"""
try:
with open(target, "a") as out_file, open(file_to_append, "r") as input_file:
for line in input_file:
out_file.write(line)
except IOError:
raise BuildVerityImageError(error_message)
def BuildVerifiedImage(data_image_path, verity_image_path,
verity_metadata_path, verity_fec_path,
padding_size, fec_supported):
Append(
verity_image_path, verity_metadata_path,
"Could not append verity metadata!")
if fec_supported:
# Build FEC for the entire partition, including metadata.
BuildVerityFEC(
data_image_path, verity_image_path, verity_fec_path, padding_size)
Append(verity_image_path, verity_fec_path, "Could not append FEC!")
Append2Simg(
data_image_path, verity_image_path, "Could not append verity data!")
def MakeVerityEnabledImage(out_file, fec_supported, prop_dict):
"""Creates an image that is verifiable using dm-verity.
Args:
out_file: the location to write the verifiable image at
prop_dict: a dictionary of properties required for image creation and
verification
Raises:
AssertionError: On invalid partition sizes.
"""
# get properties
image_size = int(prop_dict["image_size"])
block_dev = prop_dict["verity_block_device"]
signer_key = prop_dict["verity_key"] + ".pk8"
if OPTIONS.verity_signer_path is not None:
signer_path = OPTIONS.verity_signer_path
else:
signer_path = prop_dict["verity_signer_cmd"]
signer_args = OPTIONS.verity_signer_args
tempdir_name = common.MakeTempDir(suffix="_verity_images")
# Get partial image paths.
verity_image_path = os.path.join(tempdir_name, "verity.img")
verity_metadata_path = os.path.join(tempdir_name, "verity_metadata.img")
verity_fec_path = os.path.join(tempdir_name, "verity_fec.img")
# Build the verity tree and get the root hash and salt.
root_hash, salt = BuildVerityTree(out_file, verity_image_path)
# Build the metadata blocks.
verity_disable = "verity_disable" in prop_dict
BuildVerityMetadata(
image_size, verity_metadata_path, root_hash, salt, block_dev, signer_path,
signer_key, signer_args, verity_disable)
# Build the full verified image.
partition_size = int(prop_dict["partition_size"])
verity_size = int(prop_dict["verity_size"])
padding_size = partition_size - image_size - verity_size
assert padding_size >= 0
BuildVerifiedImage(
out_file, verity_image_path, verity_metadata_path, verity_fec_path,
padding_size, fec_supported)
def AVBCalcMaxImageSize(avbtool, footer_type, partition_size, additional_args):
"""Calculates max image size for a given partition size.
Args:
avbtool: String with path to avbtool.
footer_type: 'hash' or 'hashtree' for generating footer.
partition_size: The size of the partition in question.
additional_args: Additional arguments to pass to "avbtool add_hash_footer"
or "avbtool add_hashtree_footer".
Returns:
The maximum image size.
Raises:
BuildVerityImageError: On invalid image size.
"""
cmd = [avbtool, "add_%s_footer" % footer_type,
"--partition_size", str(partition_size), "--calc_max_image_size"]
cmd.extend(shlex.split(additional_args))
output = common.RunAndCheckOutput(cmd)
image_size = int(output)
if image_size <= 0:
raise BuildVerityImageError(
"Invalid max image size: {}".format(output))
return image_size
def AVBCalcMinPartitionSize(image_size, size_calculator):
"""Calculates min partition size for a given image size.
Args:
image_size: The size of the image in question.
size_calculator: The function to calculate max image size
for a given partition size.
Returns:
The minimum partition size required to accommodate the image size.
"""
# Use image size as partition size to approximate final partition size.
image_ratio = size_calculator(image_size) / float(image_size)
# Prepare a binary search for the optimal partition size.
lo = int(image_size / image_ratio) // BLOCK_SIZE * BLOCK_SIZE - BLOCK_SIZE
# Ensure lo is small enough: max_image_size should <= image_size.
delta = BLOCK_SIZE
max_image_size = size_calculator(lo)
while max_image_size > image_size:
image_ratio = max_image_size / float(lo)
lo = int(image_size / image_ratio) // BLOCK_SIZE * BLOCK_SIZE - delta
delta *= 2
max_image_size = size_calculator(lo)
hi = lo + BLOCK_SIZE
# Ensure hi is large enough: max_image_size should >= image_size.
delta = BLOCK_SIZE
max_image_size = size_calculator(hi)
while max_image_size < image_size:
image_ratio = max_image_size / float(hi)
hi = int(image_size / image_ratio) // BLOCK_SIZE * BLOCK_SIZE + delta
delta *= 2
max_image_size = size_calculator(hi)
partition_size = hi
# Start to binary search.
while lo < hi:
mid = ((lo + hi) // (2 * BLOCK_SIZE)) * BLOCK_SIZE
max_image_size = size_calculator(mid)
if max_image_size >= image_size: # if mid can accommodate image_size
if mid < partition_size: # if a smaller partition size is found
partition_size = mid
hi = mid
else:
lo = mid + BLOCK_SIZE
if OPTIONS.verbose:
print("AVBCalcMinPartitionSize({}): partition_size: {}.".format(
image_size, partition_size))
return partition_size
def AVBAddFooter(image_path, avbtool, footer_type, partition_size,
partition_name, key_path, algorithm, salt,
additional_args):
"""Adds dm-verity hashtree and AVB metadata to an image.
Args:
image_path: Path to image to modify.
avbtool: String with path to avbtool.
footer_type: 'hash' or 'hashtree' for generating footer.
partition_size: The size of the partition in question.
partition_name: The name of the partition - will be embedded in metadata.
key_path: Path to key to use or None.
algorithm: Name of algorithm to use or None.
salt: The salt to use (a hexadecimal string) or None.
additional_args: Additional arguments to pass to "avbtool add_hash_footer"
or "avbtool add_hashtree_footer".
"""
cmd = [avbtool, "add_%s_footer" % footer_type,
"--partition_size", partition_size,
"--partition_name", partition_name,
"--image", image_path]
if key_path and algorithm:
cmd.extend(["--key", key_path, "--algorithm", algorithm])
if salt:
cmd.extend(["--salt", salt])
cmd.extend(shlex.split(additional_args))
common.RunAndCheckOutput(cmd)
class HashtreeInfoGenerationError(Exception):
"""An Exception raised during hashtree info generation."""