avbtool: add_hashtree_footer: Allow omitting partition name and size.
This is useful for applications where AVB is used to verify a file
instead of a partition.
Bug: 113320014
Test: New unit tests and all unit tests pass.
Change-Id: I212af74dc5215b0c6cc4922dc67c3b68072ab9ed
diff --git a/avbtool b/avbtool
index dd54011..6f327f6 100755
--- a/avbtool
+++ b/avbtool
@@ -1081,7 +1081,8 @@
ret = desc + self.data + padding
return bytearray(ret)
- def verify(self, image_dir, image_ext, expected_chain_partitions_map):
+ def verify(self, image_dir, image_ext, expected_chain_partitions_map,
+ image_containing_descriptor):
"""Verifies contents of the descriptor - used in verify_image sub-command.
Arguments:
@@ -1089,6 +1090,7 @@
image_ext: The extension of the file being verified (e.g. '.img').
expected_chain_partitions_map: A map from partition name to the
tuple (rollback_index_location, key_blob).
+ image_containing_descriptor: The image the descriptor is in.
Returns:
True if the descriptor verifies, False otherwise.
@@ -1165,7 +1167,8 @@
ret = desc + self.key + '\0' + self.value + '\0' + padding
return bytearray(ret)
- def verify(self, image_dir, image_ext, expected_chain_partitions_map):
+ def verify(self, image_dir, image_ext, expected_chain_partitions_map,
+ image_containing_descriptor):
"""Verifies contents of the descriptor - used in verify_image sub-command.
Arguments:
@@ -1173,6 +1176,7 @@
image_ext: The extension of the file being verified (e.g. '.img').
expected_chain_partitions_map: A map from partition name to the
tuple (rollback_index_location, key_blob).
+ image_containing_descriptor: The image the descriptor is in.
Returns:
True if the descriptor verifies, False otherwise.
@@ -1325,7 +1329,8 @@
ret = desc + encoded_name + self.salt + self.root_digest + padding
return bytearray(ret)
- def verify(self, image_dir, image_ext, expected_chain_partitions_map):
+ def verify(self, image_dir, image_ext, expected_chain_partitions_map,
+ image_containing_descriptor):
"""Verifies contents of the descriptor - used in verify_image sub-command.
Arguments:
@@ -1333,12 +1338,16 @@
image_ext: The extension of the file being verified (e.g. '.img').
expected_chain_partitions_map: A map from partition name to the
tuple (rollback_index_location, key_blob).
+ image_containing_descriptor: The image the descriptor is in.
Returns:
True if the descriptor verifies, False otherwise.
"""
- image_filename = os.path.join(image_dir, self.partition_name + image_ext)
- image = ImageHandler(image_filename)
+ if self.partition_name == '':
+ image = image_containing_descriptor
+ else:
+ image_filename = os.path.join(image_dir, self.partition_name + image_ext)
+ image = ImageHandler(image_filename)
# Generate the hashtree and checks that it matches what's in the file.
digest_size = len(hashlib.new(name=self.hash_algorithm).digest())
digest_padding = round_to_pow2(digest_size) - digest_size
@@ -1367,7 +1376,7 @@
# takes a long time; and c) is not strictly needed for
# verification purposes as we've already verified the root hash.
print ('{}: Successfully verified {} hashtree of {} for image of {} bytes'
- .format(self.partition_name, self.hash_algorithm, image_filename,
+ .format(self.partition_name, self.hash_algorithm, image.filename,
self.image_size))
return True
@@ -1477,7 +1486,8 @@
ret = desc + encoded_name + self.salt + self.digest + padding
return bytearray(ret)
- def verify(self, image_dir, image_ext, expected_chain_partitions_map):
+ def verify(self, image_dir, image_ext, expected_chain_partitions_map,
+ image_containing_descriptor):
"""Verifies contents of the descriptor - used in verify_image sub-command.
Arguments:
@@ -1485,12 +1495,16 @@
image_ext: The extension of the file being verified (e.g. '.img').
expected_chain_partitions_map: A map from partition name to the
tuple (rollback_index_location, key_blob).
+ image_containing_descriptor: The image the descriptor is in.
Returns:
True if the descriptor verifies, False otherwise.
"""
- image_filename = os.path.join(image_dir, self.partition_name + image_ext)
- image = ImageHandler(image_filename)
+ if self.partition_name == '':
+ image = image_containing_descriptor
+ else:
+ image_filename = os.path.join(image_dir, self.partition_name + image_ext)
+ image = ImageHandler(image_filename)
data = image.read(self.image_size)
ha = hashlib.new(self.hash_algorithm)
ha.update(self.salt)
@@ -1502,7 +1516,7 @@
format(self.hash_algorithm, image_filename))
return False
print ('{}: Successfully verified {} hash of {} for image of {} bytes'
- .format(self.partition_name, self.hash_algorithm, image_filename,
+ .format(self.partition_name, self.hash_algorithm, image.filename,
self.image_size))
return True
@@ -1582,7 +1596,8 @@
ret = desc + encoded_str + padding
return bytearray(ret)
- def verify(self, image_dir, image_ext, expected_chain_partitions_map):
+ def verify(self, image_dir, image_ext, expected_chain_partitions_map,
+ image_containing_descriptor):
"""Verifies contents of the descriptor - used in verify_image sub-command.
Arguments:
@@ -1590,6 +1605,7 @@
image_ext: The extension of the file being verified (e.g. '.img').
expected_chain_partitions_map: A map from partition name to the
tuple (rollback_index_location, key_blob).
+ image_containing_descriptor: The image the descriptor is in.
Returns:
True if the descriptor verifies, False otherwise.
@@ -1683,7 +1699,8 @@
ret = desc + encoded_name + self.public_key + padding
return bytearray(ret)
- def verify(self, image_dir, image_ext, expected_chain_partitions_map):
+ def verify(self, image_dir, image_ext, expected_chain_partitions_map,
+ image_containing_descriptor):
"""Verifies contents of the descriptor - used in verify_image sub-command.
Arguments:
@@ -1691,6 +1708,7 @@
image_ext: The extension of the file being verified (e.g. '.img').
expected_chain_partitions_map: A map from partition name to the
tuple (rollback_index_location, key_blob).
+ image_containing_descriptor: The image the descriptor is in.
Returns:
True if the descriptor verifies, False otherwise.
@@ -2227,7 +2245,7 @@
.format(alg_name, image.filename))
for desc in descriptors:
- if not desc.verify(image_dir, image_ext, expected_chain_partitions_map):
+ if not desc.verify(image_dir, image_ext, expected_chain_partitions_map, image):
raise AvbError('Error verifying descriptor.')
# Note how AvbDescriptor.verify() method verifies only the descriptor
# contents which in the case of chain descriptors means checking only its
@@ -3126,7 +3144,7 @@
Arguments:
image_filename: File to add the footer to.
- partition_size: Size of partition.
+ partition_size: Size of partition or 0 to put it right at the end.
partition_name: Name of partition (without A/B suffix).
generate_fec: If True, generate FEC codes.
fec_num_roots: Number of roots for FEC.
@@ -3177,19 +3195,22 @@
digest_size = len(hashlib.new(name=hash_algorithm).digest())
digest_padding = round_to_pow2(digest_size) - digest_size
- # First, calculate the maximum image size such that an image
- # this size + the hashtree + metadata (footer + vbmeta struct)
- # fits in |partition_size|. We use very conservative figures for
- # metadata.
- (_, max_tree_size) = calc_hash_level_offsets(
- partition_size, block_size, digest_size + digest_padding)
- max_fec_size = 0
- if generate_fec:
- max_fec_size = calc_fec_data_size(partition_size, fec_num_roots)
- max_metadata_size = (max_fec_size + max_tree_size +
- self.MAX_VBMETA_SIZE +
- self.MAX_FOOTER_SIZE)
- max_image_size = partition_size - max_metadata_size
+ # If |partition_size| is given (e.g. not 0), calculate the maximum image
+ # size such that an image this size + the hashtree + metadata (footer +
+ # vbmeta struct) fits in |partition_size|. We use very conservative figures
+ # for metadata.
+ if partition_size > 0:
+ (_, max_tree_size) = calc_hash_level_offsets(
+ partition_size, block_size, digest_size + digest_padding)
+ max_fec_size = 0
+ if generate_fec:
+ max_fec_size = calc_fec_data_size(partition_size, fec_num_roots)
+ max_metadata_size = (max_fec_size + max_tree_size +
+ self.MAX_VBMETA_SIZE +
+ self.MAX_FOOTER_SIZE)
+ max_image_size = partition_size - max_metadata_size
+ else:
+ max_image_size = 0
# If we're asked to only calculate the maximum image size, we're done.
if calc_max_image_size:
@@ -3198,10 +3219,16 @@
image = ImageHandler(image_filename)
- if partition_size % image.block_size != 0:
- raise AvbError('Partition size of {} is not a multiple of the image '
- 'block size {}.'.format(partition_size,
- image.block_size))
+ if partition_size > 0:
+ if partition_size % image.block_size != 0:
+ raise AvbError('Partition size of {} is not a multiple of the image '
+ 'block size {}.'.format(partition_size,
+ image.block_size))
+ else:
+ if image.image_size % image.block_size != 0:
+ raise AvbError('File size of {} is not a multiple of the image '
+ 'block size {}.'.format(image.image_size,
+ image.block_size))
# If there's already a footer, truncate the image to its original
# size. This way 'avbtool add_hashtree_footer' is idempotent
@@ -3228,11 +3255,12 @@
image.append_raw('\0' * (rounded_image_size - image.image_size))
# If image size exceeds the maximum image size, fail.
- if image.image_size > max_image_size:
- raise AvbError('Image size of {} exceeds maximum image '
- 'size of {} in order to fit in a partition '
- 'size of {}.'.format(image.image_size, max_image_size,
- partition_size))
+ if partition_size > 0:
+ if image.image_size > max_image_size:
+ raise AvbError('Image size of {} exceeds maximum image '
+ 'size of {} in order to fit in a partition '
+ 'size of {}.'.format(image.image_size, max_image_size,
+ partition_size))
if salt:
salt = salt.decode('hex')
@@ -3331,8 +3359,9 @@
# Now insert a DONT_CARE chunk with enough bytes such that the
# final Footer block is at the end of partition_size..
- image.append_dont_care(partition_size - image.image_size -
- 1*image.block_size)
+ if partition_size > 0:
+ image.append_dont_care(partition_size - image.image_size -
+ 1*image.block_size)
# Generate the Footer that tells where the VBMeta footer
# is. Also put enough padding in the front of the footer since
@@ -3895,10 +3924,11 @@
type=argparse.FileType('rab+'))
sub_parser.add_argument('--partition_size',
help='Partition size',
+ default=0,
type=parse_number)
sub_parser.add_argument('--partition_name',
help='Partition name',
- default=None)
+ default='')
sub_parser.add_argument('--hash_algorithm',
help='Hash algorithm to use (default: sha1)',
default='sha1')
diff --git a/test/avbtool_unittest.cc b/test/avbtool_unittest.cc
index 0ece79f..45b1083 100644
--- a/test/avbtool_unittest.cc
+++ b/test/avbtool_unittest.cc
@@ -1603,6 +1603,75 @@
InfoImage(path));
}
+TEST_F(AvbToolTest, AddHashtreeFooterNoSizeOrName) {
+ // Size must be a multiple of block size (4096 bytes)
+ size_t file_size = 72 * 1024;
+ base::FilePath path = GenerateImage("data.bin", file_size);
+
+ // Note how there is no --partition_size or --partition_name here.
+ EXPECT_COMMAND(0,
+ "./avbtool add_hashtree_footer --salt d00df00d "
+ "--image %s "
+ "--algorithm SHA256_RSA2048 "
+ "--key test/data/testkey_rsa2048.pem "
+ "--internal_release_string \"\" ",
+ path.value().c_str());
+
+ ASSERT_EQ(
+ "Footer version: 1.0\n"
+ "Image size: 94208 bytes\n"
+ "Original image size: 73728 bytes\n"
+ "VBMeta offset: 86016\n"
+ "VBMeta size: 1344 bytes\n"
+ "--\n"
+ "Minimum libavb version: 1.0\n"
+ "Header Block: 256 bytes\n"
+ "Authentication Block: 320 bytes\n"
+ "Auxiliary Block: 768 bytes\n"
+ "Algorithm: SHA256_RSA2048\n"
+ "Rollback Index: 0\n"
+ "Flags: 0\n"
+ "Release String: ''\n"
+ "Descriptors:\n"
+ " Hashtree descriptor:\n"
+ " Version of dm-verity: 1\n"
+ " Image Size: 73728 bytes\n"
+ " Tree Offset: 73728\n"
+ " Tree Size: 4096 bytes\n"
+ " Data Block Size: 4096 bytes\n"
+ " Hash Block Size: 4096 bytes\n"
+ " FEC num roots: 2\n"
+ " FEC offset: 77824\n"
+ " FEC size: 8192 bytes\n"
+ " Hash Algorithm: sha1\n"
+ " Partition Name: \n"
+ " Salt: d00df00d\n"
+ " Root Digest: 2f73fb340e982794643e1121d82d5195677c2b31\n"
+ " Flags: 0\n",
+ InfoImage(path));
+
+ // Check that at least avbtool can verify the image and hashtree.
+ EXPECT_COMMAND(0,
+ "./avbtool verify_image "
+ "--image %s ",
+ path.value().c_str());
+}
+
+TEST_F(AvbToolTest, AddHashtreeFooterNoSizeWrongSize) {
+ // Size must be a multiple of block size (4096 bytes) and this one isn't...
+ size_t file_size = 70 * 1024;
+ base::FilePath path = GenerateImage("data.bin", file_size);
+
+ // ... so we expect this command to fail.
+ EXPECT_COMMAND(1,
+ "./avbtool add_hashtree_footer --salt d00df00d "
+ "--image %s "
+ "--algorithm SHA256_RSA2048 "
+ "--key test/data/testkey_rsa2048.pem "
+ "--internal_release_string \"\" ",
+ path.value().c_str());
+}
+
TEST_F(AvbToolTest, KernelCmdlineDescriptor) {
base::FilePath vbmeta_path =
testdir_.Append("vbmeta_kernel_cmdline_desc.bin");