[build] avbtool -> avbtool.py
Note we have to retain the original avbtool for a soft transition.
Will delete it in a follow-up.
Bug: 64359
Change-Id: I86d8fe0d161051edc917aa7184a2f4982ceccab8
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/450606
Reviewed-by: Petr Hosek <phosek@google.com>
Commit-Queue: Auto-Submit <auto-submit@fuchsia-infra.iam.gserviceaccount.com>
Testability-Review: Shai Barack <shayba@google.com>
Fuchsia-Auto-Submit: Shai Barack <shayba@google.com>
diff --git a/build/images/vbmeta.gni b/build/images/vbmeta.gni
index 5c81b28..83f38fb 100644
--- a/build/images/vbmeta.gni
+++ b/build/images/vbmeta.gni
@@ -112,7 +112,7 @@
}
action("${target_name}__vb_desc") {
- script = "//zircon/third_party/tools/android/avb/avbtool"
+ script = "//zircon/third_party/tools/android/avb/avbtool.py"
forward_variables_from(invoker,
[
@@ -146,7 +146,7 @@
}
action(target_name) {
- script = "//zircon/third_party/tools/android/avb/avbtool"
+ script = "//zircon/third_party/tools/android/avb/avbtool.py"
forward_variables_from(invoker,
[
diff --git a/zircon/third_party/tools/android/avb/avbtool.py b/zircon/third_party/tools/android/avb/avbtool.py
new file mode 100755
index 0000000..753905c
--- /dev/null
+++ b/zircon/third_party/tools/android/avb/avbtool.py
@@ -0,0 +1,5171 @@
+#!/usr/bin/env python3
+
+# Copyright 2016, The Android Open Source Project
+#
+# Permission is hereby granted, free of charge, to any person
+# obtaining a copy of this software and associated documentation
+# files (the "Software"), to deal in the Software without
+# restriction, including without limitation the rights to use, copy,
+# modify, merge, publish, distribute, sublicense, and/or sell copies
+# of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+#
+"""Command-line tool for working with Android Verified Boot images."""
+
+import argparse
+import binascii
+import bisect
+import hashlib
+import json
+import math
+import os
+import struct
+import subprocess
+import sys
+import tempfile
+import time
+
+# Keep in sync with libavb/avb_version.h.
+AVB_VERSION_MAJOR = 1
+AVB_VERSION_MINOR = 2
+AVB_VERSION_SUB = 0
+
+# Keep in sync with libavb/avb_footer.h.
+AVB_FOOTER_VERSION_MAJOR = 1
+AVB_FOOTER_VERSION_MINOR = 0
+
+AVB_VBMETA_IMAGE_FLAGS_HASHTREE_DISABLED = 1
+
+# Configuration for enabling logging of calls to avbtool.
+AVB_INVOCATION_LOGFILE = os.environ.get('AVB_INVOCATION_LOGFILE')
+
+
+class AvbError(Exception):
+ """Application-specific errors.
+
+ These errors represent issues for which a stack-trace should not be
+ presented.
+
+ Attributes:
+ message: Error message.
+ """
+
+ def __init__(self, message):
+ Exception.__init__(self, message)
+
+
+class Algorithm(object):
+ """Contains details about an algorithm.
+
+ See the avb_vbmeta_image.h file for more details about algorithms.
+
+ The constant |ALGORITHMS| is a dictionary from human-readable
+ names (e.g 'SHA256_RSA2048') to instances of this class.
+
+ Attributes:
+ algorithm_type: Integer code corresponding to |AvbAlgorithmType|.
+ hash_name: Empty or a name from |hashlib.algorithms|.
+ hash_num_bytes: Number of bytes used to store the hash.
+ signature_num_bytes: Number of bytes used to store the signature.
+ public_key_num_bytes: Number of bytes used to store the public key.
+ padding: Padding used for signature as bytes, if any.
+ """
+
+ def __init__(
+ self, algorithm_type, hash_name, hash_num_bytes,
+ signature_num_bytes, public_key_num_bytes, padding):
+ self.algorithm_type = algorithm_type
+ self.hash_name = hash_name
+ self.hash_num_bytes = hash_num_bytes
+ self.signature_num_bytes = signature_num_bytes
+ self.public_key_num_bytes = public_key_num_bytes
+ self.padding = padding
+
+
+# This must be kept in sync with the avb_crypto.h file.
+#
+# The PKC1-v1.5 padding is a blob of binary DER of ASN.1 and is
+# obtained from section 5.2.2 of RFC 4880.
+ALGORITHMS = {
+ 'NONE':
+ Algorithm(
+ algorithm_type=0, # AVB_ALGORITHM_TYPE_NONE
+ hash_name='',
+ hash_num_bytes=0,
+ signature_num_bytes=0,
+ public_key_num_bytes=0,
+ padding=b''),
+ 'SHA256_RSA2048':
+ Algorithm(
+ algorithm_type=1, # AVB_ALGORITHM_TYPE_SHA256_RSA2048
+ hash_name='sha256',
+ hash_num_bytes=32,
+ signature_num_bytes=256,
+ public_key_num_bytes=8 + 2 * 2048 // 8,
+ padding=bytes(
+ bytearray(
+ [
+ # PKCS1-v1_5 padding
+ 0x00,
+ 0x01
+ ] + [0xff] * 202 + [0x00] + [
+ # ASN.1 header
+ 0x30,
+ 0x31,
+ 0x30,
+ 0x0d,
+ 0x06,
+ 0x09,
+ 0x60,
+ 0x86,
+ 0x48,
+ 0x01,
+ 0x65,
+ 0x03,
+ 0x04,
+ 0x02,
+ 0x01,
+ 0x05,
+ 0x00,
+ 0x04,
+ 0x20,
+ ]))),
+ 'SHA256_RSA4096':
+ Algorithm(
+ algorithm_type=2, # AVB_ALGORITHM_TYPE_SHA256_RSA4096
+ hash_name='sha256',
+ hash_num_bytes=32,
+ signature_num_bytes=512,
+ public_key_num_bytes=8 + 2 * 4096 // 8,
+ padding=bytes(
+ bytearray(
+ [
+ # PKCS1-v1_5 padding
+ 0x00,
+ 0x01
+ ] + [0xff] * 458 + [0x00] + [
+ # ASN.1 header
+ 0x30,
+ 0x31,
+ 0x30,
+ 0x0d,
+ 0x06,
+ 0x09,
+ 0x60,
+ 0x86,
+ 0x48,
+ 0x01,
+ 0x65,
+ 0x03,
+ 0x04,
+ 0x02,
+ 0x01,
+ 0x05,
+ 0x00,
+ 0x04,
+ 0x20,
+ ]))),
+ 'SHA256_RSA8192':
+ Algorithm(
+ algorithm_type=3, # AVB_ALGORITHM_TYPE_SHA256_RSA8192
+ hash_name='sha256',
+ hash_num_bytes=32,
+ signature_num_bytes=1024,
+ public_key_num_bytes=8 + 2 * 8192 // 8,
+ padding=bytes(
+ bytearray(
+ [
+ # PKCS1-v1_5 padding
+ 0x00,
+ 0x01
+ ] + [0xff] * 970 + [0x00] + [
+ # ASN.1 header
+ 0x30,
+ 0x31,
+ 0x30,
+ 0x0d,
+ 0x06,
+ 0x09,
+ 0x60,
+ 0x86,
+ 0x48,
+ 0x01,
+ 0x65,
+ 0x03,
+ 0x04,
+ 0x02,
+ 0x01,
+ 0x05,
+ 0x00,
+ 0x04,
+ 0x20,
+ ]))),
+ 'SHA512_RSA2048':
+ Algorithm(
+ algorithm_type=4, # AVB_ALGORITHM_TYPE_SHA512_RSA2048
+ hash_name='sha512',
+ hash_num_bytes=64,
+ signature_num_bytes=256,
+ public_key_num_bytes=8 + 2 * 2048 // 8,
+ padding=bytes(
+ bytearray(
+ [
+ # PKCS1-v1_5 padding
+ 0x00,
+ 0x01
+ ] + [0xff] * 170 + [0x00] + [
+ # ASN.1 header
+ 0x30,
+ 0x51,
+ 0x30,
+ 0x0d,
+ 0x06,
+ 0x09,
+ 0x60,
+ 0x86,
+ 0x48,
+ 0x01,
+ 0x65,
+ 0x03,
+ 0x04,
+ 0x02,
+ 0x03,
+ 0x05,
+ 0x00,
+ 0x04,
+ 0x40
+ ]))),
+ 'SHA512_RSA4096':
+ Algorithm(
+ algorithm_type=5, # AVB_ALGORITHM_TYPE_SHA512_RSA4096
+ hash_name='sha512',
+ hash_num_bytes=64,
+ signature_num_bytes=512,
+ public_key_num_bytes=8 + 2 * 4096 // 8,
+ padding=bytes(
+ bytearray(
+ [
+ # PKCS1-v1_5 padding
+ 0x00,
+ 0x01
+ ] + [0xff] * 426 + [0x00] + [
+ # ASN.1 header
+ 0x30,
+ 0x51,
+ 0x30,
+ 0x0d,
+ 0x06,
+ 0x09,
+ 0x60,
+ 0x86,
+ 0x48,
+ 0x01,
+ 0x65,
+ 0x03,
+ 0x04,
+ 0x02,
+ 0x03,
+ 0x05,
+ 0x00,
+ 0x04,
+ 0x40
+ ]))),
+ 'SHA512_RSA8192':
+ Algorithm(
+ algorithm_type=6, # AVB_ALGORITHM_TYPE_SHA512_RSA8192
+ hash_name='sha512',
+ hash_num_bytes=64,
+ signature_num_bytes=1024,
+ public_key_num_bytes=8 + 2 * 8192 // 8,
+ padding=bytes(
+ bytearray(
+ [
+ # PKCS1-v1_5 padding
+ 0x00,
+ 0x01
+ ] + [0xff] * 938 + [0x00] + [
+ # ASN.1 header
+ 0x30,
+ 0x51,
+ 0x30,
+ 0x0d,
+ 0x06,
+ 0x09,
+ 0x60,
+ 0x86,
+ 0x48,
+ 0x01,
+ 0x65,
+ 0x03,
+ 0x04,
+ 0x02,
+ 0x03,
+ 0x05,
+ 0x00,
+ 0x04,
+ 0x40
+ ]))),
+}
+
+
+def get_release_string():
+ """Calculates the release string to use in the VBMeta struct."""
+ # Keep in sync with libavb/avb_version.c:avb_version_string().
+ return 'avbtool {}.{}.{}'.format(
+ AVB_VERSION_MAJOR, AVB_VERSION_MINOR, AVB_VERSION_SUB)
+
+
+def round_to_multiple(number, size):
+ """Rounds a number up to nearest multiple of another number.
+
+ Arguments:
+ number: The number to round up.
+ size: The multiple to round up to.
+
+ Returns:
+ If |number| is a multiple of |size|, returns |number|, otherwise
+ returns |number| + |size|.
+ """
+ remainder = number % size
+ if remainder == 0:
+ return number
+ return number + size - remainder
+
+
+def round_to_pow2(number):
+ """Rounds a number up to the next power of 2.
+
+ Arguments:
+ number: The number to round up.
+
+ Returns:
+ If |number| is already a power of 2 then |number| is
+ returned. Otherwise the smallest power of 2 greater than |number|
+ is returned.
+ """
+ return 2**((number - 1).bit_length())
+
+
+def encode_long(num_bits, value):
+ """Encodes a long to a bytearray() using a given amount of bits.
+
+ This number is written big-endian, e.g. with the most significant
+ bit first.
+
+ This is the reverse of decode_long().
+
+ Arguments:
+ num_bits: The number of bits to write, e.g. 2048.
+ value: The value to write.
+
+ Returns:
+ A bytearray() with the encoded long.
+ """
+ ret = bytearray()
+ for bit_pos in range(num_bits, 0, -8):
+ octet = (value >> (bit_pos - 8)) & 0xff
+ ret.extend(struct.pack('!B', octet))
+ return ret
+
+
+def decode_long(blob):
+ """Decodes a long from a bytearray() using a given amount of bits.
+
+ This number is expected to be in big-endian, e.g. with the most
+ significant bit first.
+
+ This is the reverse of encode_long().
+
+ Arguments:
+ blob: A bytearray() with the encoded long.
+
+ Returns:
+ The decoded value.
+ """
+ ret = 0
+ for b in bytearray(blob):
+ ret *= 256
+ ret += b
+ return ret
+
+
+def egcd(a, b):
+ """Calculate greatest common divisor of two numbers.
+
+ This implementation uses a recursive version of the extended
+ Euclidian algorithm.
+
+ Arguments:
+ a: First number.
+ b: Second number.
+
+ Returns:
+ A tuple (gcd, x, y) that where |gcd| is the greatest common
+ divisor of |a| and |b| and |a|*|x| + |b|*|y| = |gcd|.
+ """
+ if a == 0:
+ return (b, 0, 1)
+ g, y, x = egcd(b % a, a)
+ return (g, x - (b // a) * y, y)
+
+
+def modinv(a, m):
+ """Calculate modular multiplicative inverse of |a| modulo |m|.
+
+ This calculates the number |x| such that |a| * |x| == 1 (modulo
+ |m|). This number only exists if |a| and |m| are co-prime - |None|
+ is returned if this isn't true.
+
+ Arguments:
+ a: The number to calculate a modular inverse of.
+ m: The modulo to use.
+
+ Returns:
+ The modular multiplicative inverse of |a| and |m| or |None| if
+ these numbers are not co-prime.
+ """
+ gcd, x, _ = egcd(a, m)
+ if gcd != 1:
+ return None # modular inverse does not exist
+ return x % m
+
+
+def parse_number(string):
+ """Parse a string as a number.
+
+ This is just a short-hand for int(string, 0) suitable for use in the
+ |type| parameter of |ArgumentParser|'s add_argument() function. An
+ improvement to just using type=int is that this function supports
+ numbers in other bases, e.g. "0x1234".
+
+ Arguments:
+ string: The string to parse.
+
+ Returns:
+ The parsed integer.
+
+ Raises:
+ ValueError: If the number could not be parsed.
+ """
+ return int(string, 0)
+
+
+class RSAPublicKey(object):
+ """Data structure used for a RSA public key.
+
+ Attributes:
+ exponent: The key exponent.
+ modulus: The key modulus.
+ num_bits: The key size.
+ """
+
+ MODULUS_PREFIX = b'modulus='
+
+ def __init__(self, key_path):
+ """Loads and parses an RSA key from either a private or public key file.
+
+ Arguments:
+ key_path: The path to a key file.
+
+ Raises:
+ AvbError: If RSA key parameters could not be read from file.
+ """
+ # We used to have something as simple as this:
+ #
+ # key = Crypto.PublicKey.RSA.importKey(open(key_path).read())
+ # self.exponent = key.e
+ # self.modulus = key.n
+ # self.num_bits = key.size() + 1
+ #
+ # but unfortunately PyCrypto is not available in the builder. So
+ # instead just parse openssl(1) output to get this
+ # information. It's ugly but...
+ args = ['openssl', 'rsa', '-in', key_path, '-modulus', '-noout']
+ p = subprocess.Popen(
+ args,
+ stdin=subprocess.PIPE,
+ stdout=subprocess.PIPE,
+ stderr=subprocess.PIPE)
+ (pout, perr) = p.communicate()
+ if p.wait() != 0:
+ # Could be just a public key is passed, try that.
+ args.append('-pubin')
+ p = subprocess.Popen(
+ args,
+ stdin=subprocess.PIPE,
+ stdout=subprocess.PIPE,
+ stderr=subprocess.PIPE)
+ (pout, perr) = p.communicate()
+ if p.wait() != 0:
+ raise AvbError('Error getting public key: {}'.format(perr))
+
+ if not pout.lower().startswith(self.MODULUS_PREFIX):
+ raise AvbError('Unexpected modulus output')
+
+ modulus_hexstr = pout[len(self.MODULUS_PREFIX):]
+
+ # The exponent is assumed to always be 65537 and the number of
+ # bits can be derived from the modulus by rounding up to the
+ # nearest power of 2.
+ self.key_path = key_path
+ self.modulus = int(modulus_hexstr, 16)
+ self.num_bits = round_to_pow2(int(math.ceil(math.log(self.modulus, 2))))
+ self.exponent = 65537
+
+ def encode(self):
+ """Encodes the public RSA key in |AvbRSAPublicKeyHeader| format.
+
+ This creates a |AvbRSAPublicKeyHeader| as well as the two large
+ numbers (|key_num_bits| bits long) following it.
+
+ Returns:
+ The |AvbRSAPublicKeyHeader| followed by two large numbers as bytes.
+
+ Raises:
+ AvbError: If given RSA key exponent is not 65537.
+ """
+ if self.exponent != 65537:
+ raise AvbError('Only RSA keys with exponent 65537 are supported.')
+ ret = bytearray()
+ # Calculate n0inv = -1/n[0] (mod 2^32)
+ b = 2**32
+ n0inv = b - modinv(self.modulus, b)
+ # Calculate rr = r^2 (mod N), where r = 2^(# of key bits)
+ r = 2**self.modulus.bit_length()
+ rrmodn = r * r % self.modulus
+ ret.extend(struct.pack('!II', self.num_bits, n0inv))
+ ret.extend(encode_long(self.num_bits, self.modulus))
+ ret.extend(encode_long(self.num_bits, rrmodn))
+ return bytes(ret)
+
+ def sign(
+ self,
+ algorithm_name,
+ data_to_sign,
+ signing_helper=None,
+ signing_helper_with_files=None):
+ """Sign given data using |signing_helper| or openssl.
+
+ openssl is used if neither the parameters signing_helper nor
+ signing_helper_with_files are given.
+
+ Arguments:
+ algorithm_name: The algorithm name as per the ALGORITHMS dict.
+ data_to_sign: Data to sign as bytes or bytearray.
+ signing_helper: Program which signs a hash and returns the signature.
+ signing_helper_with_files: Same as signing_helper but uses files instead.
+
+ Returns:
+ The signature as bytes.
+
+ Raises:
+ AvbError: If an error occurred during signing.
+ """
+ # Checks requested algorithm for validity.
+ algorithm = ALGORITHMS.get(algorithm_name)
+ if not algorithm:
+ raise AvbError(
+ 'Algorithm with name {} is not supported.'.format(
+ algorithm_name))
+
+ if self.num_bits != (algorithm.signature_num_bytes * 8):
+ raise AvbError(
+ 'Key size of key ({} bits) does not match key size '
+ '({} bits) of given algorithm {}.'.format(
+ self.num_bits, algorithm.signature_num_bytes * 8,
+ algorithm_name))
+
+ # Hashes the data.
+ hasher = hashlib.new(algorithm.hash_name)
+ hasher.update(data_to_sign)
+ digest = hasher.digest()
+
+ # Calculates the signature.
+ padding_and_hash = algorithm.padding + digest
+ p = None
+ if signing_helper_with_files is not None:
+ with tempfile.NamedTemporaryFile() as signing_file:
+ signing_file.write(padding_and_hash)
+ signing_file.flush()
+ p = subprocess.Popen(
+ [
+ signing_helper_with_files, algorithm_name,
+ self.key_path, signing_file.name
+ ])
+ retcode = p.wait()
+ if retcode != 0:
+ raise AvbError('Error signing')
+ signing_file.seek(0)
+ signature = signing_file.read()
+ else:
+ if signing_helper is not None:
+ p = subprocess.Popen(
+ [signing_helper, algorithm_name, self.key_path],
+ stdin=subprocess.PIPE,
+ stdout=subprocess.PIPE,
+ stderr=subprocess.PIPE)
+ else:
+ p = subprocess.Popen(
+ [
+ 'openssl', 'rsautl', '-sign', '-inkey', self.key_path,
+ '-raw'
+ ],
+ stdin=subprocess.PIPE,
+ stdout=subprocess.PIPE,
+ stderr=subprocess.PIPE)
+ (pout, perr) = p.communicate(padding_and_hash)
+ retcode = p.wait()
+ if retcode != 0:
+ raise AvbError('Error signing: {}'.format(perr))
+ signature = pout
+ if len(signature) != algorithm.signature_num_bytes:
+ raise AvbError('Error signing: Invalid length of signature')
+ return signature
+
+
+def lookup_algorithm_by_type(alg_type):
+ """Looks up algorithm by type.
+
+ Arguments:
+ alg_type: The integer representing the type.
+
+ Returns:
+ A tuple with the algorithm name and an |Algorithm| instance.
+
+ Raises:
+ Exception: If the algorithm cannot be found
+ """
+ for alg_name in ALGORITHMS:
+ alg_data = ALGORITHMS[alg_name]
+ if alg_data.algorithm_type == alg_type:
+ return (alg_name, alg_data)
+ raise AvbError('Unknown algorithm type {}'.format(alg_type))
+
+
+def lookup_hash_size_by_type(alg_type):
+ """Looks up hash size by type.
+
+ Arguments:
+ alg_type: The integer representing the type.
+
+ Returns:
+ The corresponding hash size.
+
+ Raises:
+ AvbError: If the algorithm cannot be found.
+ """
+ for alg_name in ALGORITHMS:
+ alg_data = ALGORITHMS[alg_name]
+ if alg_data.algorithm_type == alg_type:
+ return alg_data.hash_num_bytes
+ raise AvbError('Unsupported algorithm type {}'.format(alg_type))
+
+
+def verify_vbmeta_signature(vbmeta_header, vbmeta_blob):
+ """Checks that signature in a vbmeta blob was made by the embedded public key.
+
+ Arguments:
+ vbmeta_header: A AvbVBMetaHeader.
+ vbmeta_blob: The whole vbmeta blob, including the header as bytes or
+ bytearray.
+
+ Returns:
+ True if the signature is valid and corresponds to the embedded
+ public key. Also returns True if the vbmeta blob is not signed.
+
+ Raises:
+ AvbError: If there errors calling out to openssl command during
+ signature verification.
+ """
+ (_, alg) = lookup_algorithm_by_type(vbmeta_header.algorithm_type)
+ if not alg.hash_name:
+ return True
+ header_blob = vbmeta_blob[0:256]
+ auth_offset = 256
+ aux_offset = auth_offset + vbmeta_header.authentication_data_block_size
+ aux_size = vbmeta_header.auxiliary_data_block_size
+ aux_blob = vbmeta_blob[aux_offset:aux_offset + aux_size]
+ pubkey_offset = aux_offset + vbmeta_header.public_key_offset
+ pubkey_size = vbmeta_header.public_key_size
+ pubkey_blob = vbmeta_blob[pubkey_offset:pubkey_offset + pubkey_size]
+
+ digest_offset = auth_offset + vbmeta_header.hash_offset
+ digest_size = vbmeta_header.hash_size
+ digest_blob = vbmeta_blob[digest_offset:digest_offset + digest_size]
+
+ sig_offset = auth_offset + vbmeta_header.signature_offset
+ sig_size = vbmeta_header.signature_size
+ sig_blob = vbmeta_blob[sig_offset:sig_offset + sig_size]
+
+ # Now that we've got the stored digest, public key, and signature
+ # all we need to do is to verify. This is the exactly the same
+ # steps as performed in the avb_vbmeta_image_verify() function in
+ # libavb/avb_vbmeta_image.c.
+
+ ha = hashlib.new(alg.hash_name)
+ ha.update(header_blob)
+ ha.update(aux_blob)
+ computed_digest = ha.digest()
+
+ if computed_digest != digest_blob:
+ return False
+
+ padding_and_digest = alg.padding + computed_digest
+
+ (num_bits,) = struct.unpack('!I', pubkey_blob[0:4])
+ modulus_blob = pubkey_blob[8:8 + num_bits // 8]
+ modulus = decode_long(modulus_blob)
+ exponent = 65537
+
+ # We used to have this:
+ #
+ # import Crypto.PublicKey.RSA
+ # key = Crypto.PublicKey.RSA.construct((modulus, long(exponent)))
+ # if not key.verify(decode_long(padding_and_digest),
+ # (decode_long(sig_blob), None)):
+ # return False
+ # return True
+ #
+ # but since 'avbtool verify_image' is used on the builders we don't want
+ # to rely on Crypto.PublicKey.RSA. Instead just use openssl(1) to verify.
+ asn1_str = (
+ 'asn1=SEQUENCE:pubkeyinfo\n'
+ '\n'
+ '[pubkeyinfo]\n'
+ 'algorithm=SEQUENCE:rsa_alg\n'
+ 'pubkey=BITWRAP,SEQUENCE:rsapubkey\n'
+ '\n'
+ '[rsa_alg]\n'
+ 'algorithm=OID:rsaEncryption\n'
+ 'parameter=NULL\n'
+ '\n'
+ '[rsapubkey]\n'
+ 'n=INTEGER:{}\n'
+ 'e=INTEGER:{}\n').format(
+ hex(modulus).rstrip('L'),
+ hex(exponent).rstrip('L'))
+
+ with tempfile.NamedTemporaryFile() as asn1_tmpfile:
+ asn1_tmpfile.write(asn1_str.encode('ascii'))
+ asn1_tmpfile.flush()
+
+ with tempfile.NamedTemporaryFile() as der_tmpfile:
+ p = subprocess.Popen(
+ [
+ 'openssl', 'asn1parse', '-genconf', asn1_tmpfile.name,
+ '-out', der_tmpfile.name, '-noout'
+ ])
+ retcode = p.wait()
+ if retcode != 0:
+ raise AvbError('Error generating DER file')
+
+ p = subprocess.Popen(
+ [
+ 'openssl', 'rsautl', '-verify', '-pubin', '-inkey',
+ der_tmpfile.name, '-keyform', 'DER', '-raw'
+ ],
+ stdin=subprocess.PIPE,
+ stdout=subprocess.PIPE,
+ stderr=subprocess.PIPE)
+ (pout, perr) = p.communicate(sig_blob)
+ retcode = p.wait()
+ if retcode != 0:
+ raise AvbError('Error verifying data: {}'.format(perr))
+ if pout != padding_and_digest:
+ sys.stderr.write('Signature not correct\n')
+ return False
+ return True
+
+
+class ImageChunk(object):
+ """Data structure used for representing chunks in Android sparse files.
+
+ Attributes:
+ chunk_type: One of TYPE_RAW, TYPE_FILL, or TYPE_DONT_CARE.
+ chunk_offset: Offset in the sparse file where this chunk begins.
+ output_offset: Offset in de-sparsified file where output begins.
+ output_size: Number of bytes in output.
+ input_offset: Offset in sparse file for data if TYPE_RAW otherwise None.
+ fill_data: Blob with data to fill if TYPE_FILL otherwise None.
+ """
+
+ FORMAT = '<2H2I'
+ TYPE_RAW = 0xcac1
+ TYPE_FILL = 0xcac2
+ TYPE_DONT_CARE = 0xcac3
+ TYPE_CRC32 = 0xcac4
+
+ def __init__(
+ self, chunk_type, chunk_offset, output_offset, output_size,
+ input_offset, fill_data):
+ """Initializes an ImageChunk object.
+
+ Arguments:
+ chunk_type: One of TYPE_RAW, TYPE_FILL, or TYPE_DONT_CARE.
+ chunk_offset: Offset in the sparse file where this chunk begins.
+ output_offset: Offset in de-sparsified file.
+ output_size: Number of bytes in output.
+ input_offset: Offset in sparse file if TYPE_RAW otherwise None.
+ fill_data: Blob as bytes with data to fill if TYPE_FILL otherwise None.
+
+ Raises:
+ ValueError: If given chunk parameters are invalid.
+ """
+ self.chunk_type = chunk_type
+ self.chunk_offset = chunk_offset
+ self.output_offset = output_offset
+ self.output_size = output_size
+ self.input_offset = input_offset
+ self.fill_data = fill_data
+ # Check invariants.
+ if self.chunk_type == self.TYPE_RAW:
+ if self.fill_data is not None:
+ raise ValueError('RAW chunk cannot have fill_data set.')
+ if not self.input_offset:
+ raise ValueError('RAW chunk must have input_offset set.')
+ elif self.chunk_type == self.TYPE_FILL:
+ if self.fill_data is None:
+ raise ValueError('FILL chunk must have fill_data set.')
+ if self.input_offset:
+ raise ValueError('FILL chunk cannot have input_offset set.')
+ elif self.chunk_type == self.TYPE_DONT_CARE:
+ if self.fill_data is not None:
+ raise ValueError('DONT_CARE chunk cannot have fill_data set.')
+ if self.input_offset:
+ raise ValueError(
+ 'DONT_CARE chunk cannot have input_offset set.')
+ else:
+ raise ValueError('Invalid chunk type')
+
+
+class ImageHandler(object):
+ """Abstraction for image I/O with support for Android sparse images.
+
+ This class provides an interface for working with image files that
+ may be using the Android Sparse Image format. When an instance is
+ constructed, we test whether it's an Android sparse file. If so,
+ operations will be on the sparse file by interpreting the sparse
+ format, otherwise they will be directly on the file. Either way the
+ operations do the same.
+
+ For reading, this interface mimics a file object - it has seek(),
+ tell(), and read() methods. For writing, only truncation
+ (truncate()) and appending is supported (append_raw() and
+ append_dont_care()). Additionally, data can only be written in units
+ of the block size.
+
+ Attributes:
+ filename: Name of file.
+ is_sparse: Whether the file being operated on is sparse.
+ block_size: The block size, typically 4096.
+ image_size: The size of the unsparsified file.
+ """
+ # See system/core/libsparse/sparse_format.h for details.
+ MAGIC = 0xed26ff3a
+ HEADER_FORMAT = '<I4H4I'
+
+ # These are formats and offset of just the |total_chunks| and
+ # |total_blocks| fields.
+ NUM_CHUNKS_AND_BLOCKS_FORMAT = '<II'
+ NUM_CHUNKS_AND_BLOCKS_OFFSET = 16
+
+ def __init__(self, image_filename, read_only=False):
+ """Initializes an image handler.
+
+ Arguments:
+ image_filename: The name of the file to operate on.
+ read_only: True if file is only opened for read-only operations.
+
+ Raises:
+ ValueError: If data in the file is invalid.
+ """
+ self.filename = image_filename
+ self._num_total_blocks = 0
+ self._num_total_chunks = 0
+ self._file_pos = 0
+ self._read_only = read_only
+ self._read_header()
+
+ def _read_header(self):
+ """Initializes internal data structures used for reading file.
+
+ This may be called multiple times and is typically called after
+ modifying the file (e.g. appending, truncation).
+
+ Raises:
+ ValueError: If data in the file is invalid.
+ """
+ self.is_sparse = False
+ self.block_size = 4096
+ self._file_pos = 0
+ if self._read_only:
+ self._image = open(self.filename, 'rb')
+ else:
+ self._image = open(self.filename, 'r+b')
+ self._image.seek(0, os.SEEK_END)
+ self.image_size = self._image.tell()
+
+ self._image.seek(0, os.SEEK_SET)
+ header_bin = self._image.read(struct.calcsize(self.HEADER_FORMAT))
+ (
+ magic, major_version, minor_version, file_hdr_sz, chunk_hdr_sz,
+ block_size, self._num_total_blocks, self._num_total_chunks,
+ _) = struct.unpack(self.HEADER_FORMAT, header_bin)
+ if magic != self.MAGIC:
+ # Not a sparse image, our job here is done.
+ return
+ if not (major_version == 1 and minor_version == 0):
+ raise ValueError(
+ 'Encountered sparse image format version {}.{} but '
+ 'only 1.0 is supported'.format(major_version, minor_version))
+ if file_hdr_sz != struct.calcsize(self.HEADER_FORMAT):
+ raise ValueError(
+ 'Unexpected file_hdr_sz value {}.'.format(file_hdr_sz))
+ if chunk_hdr_sz != struct.calcsize(ImageChunk.FORMAT):
+ raise ValueError(
+ 'Unexpected chunk_hdr_sz value {}.'.format(chunk_hdr_sz))
+
+ self.block_size = block_size
+
+ # Build an list of chunks by parsing the file.
+ self._chunks = []
+
+ # Find the smallest offset where only "Don't care" chunks
+ # follow. This will be the size of the content in the sparse
+ # image.
+ offset = 0
+ output_offset = 0
+ for _ in range(1, self._num_total_chunks + 1):
+ chunk_offset = self._image.tell()
+
+ header_bin = self._image.read(struct.calcsize(ImageChunk.FORMAT))
+ (chunk_type, _, chunk_sz,
+ total_sz) = struct.unpack(ImageChunk.FORMAT, header_bin)
+ data_sz = total_sz - struct.calcsize(ImageChunk.FORMAT)
+
+ if chunk_type == ImageChunk.TYPE_RAW:
+ if data_sz != (chunk_sz * self.block_size):
+ raise ValueError(
+ 'Raw chunk input size ({}) does not match output '
+ 'size ({})'.format(data_sz, chunk_sz * self.block_size))
+ self._chunks.append(
+ ImageChunk(
+ ImageChunk.TYPE_RAW, chunk_offset, output_offset,
+ chunk_sz * self.block_size, self._image.tell(), None))
+ self._image.seek(data_sz, os.SEEK_CUR)
+
+ elif chunk_type == ImageChunk.TYPE_FILL:
+ if data_sz != 4:
+ raise ValueError(
+ 'Fill chunk should have 4 bytes of fill, but this '
+ 'has {}'.format(data_sz))
+ fill_data = self._image.read(4)
+ self._chunks.append(
+ ImageChunk(
+ ImageChunk.TYPE_FILL, chunk_offset, output_offset,
+ chunk_sz * self.block_size, None, fill_data))
+ elif chunk_type == ImageChunk.TYPE_DONT_CARE:
+ if data_sz != 0:
+ raise ValueError(
+ 'Don\'t care chunk input size is non-zero ({})'.format(
+ data_sz))
+ self._chunks.append(
+ ImageChunk(
+ ImageChunk.TYPE_DONT_CARE, chunk_offset, output_offset,
+ chunk_sz * self.block_size, None, None))
+ elif chunk_type == ImageChunk.TYPE_CRC32:
+ if data_sz != 4:
+ raise ValueError(
+ 'CRC32 chunk should have 4 bytes of CRC, but '
+ 'this has {}'.format(data_sz))
+ self._image.read(4)
+ else:
+ raise ValueError('Unknown chunk type {}'.format(chunk_type))
+
+ offset += chunk_sz
+ output_offset += chunk_sz * self.block_size
+
+ # Record where sparse data end.
+ self._sparse_end = self._image.tell()
+
+ # Now that we've traversed all chunks, sanity check.
+ if self._num_total_blocks != offset:
+ raise ValueError(
+ 'The header said we should have {} output blocks, '
+ 'but we saw {}'.format(self._num_total_blocks, offset))
+ junk_len = len(self._image.read())
+ if junk_len > 0:
+ raise ValueError(
+ 'There were {} bytes of extra data at the end of the '
+ 'file.'.format(junk_len))
+
+ # Assign |image_size|.
+ self.image_size = output_offset
+
+ # This is used when bisecting in read() to find the initial slice.
+ self._chunk_output_offsets = [i.output_offset for i in self._chunks]
+
+ self.is_sparse = True
+
+ def _update_chunks_and_blocks(self):
+ """Helper function to update the image header.
+
+ The the |total_chunks| and |total_blocks| fields in the header
+ will be set to value of the |_num_total_blocks| and
+ |_num_total_chunks| attributes.
+
+ """
+ self._image.seek(self.NUM_CHUNKS_AND_BLOCKS_OFFSET, os.SEEK_SET)
+ self._image.write(
+ struct.pack(
+ self.NUM_CHUNKS_AND_BLOCKS_FORMAT, self._num_total_blocks,
+ self._num_total_chunks))
+
+ def append_dont_care(self, num_bytes):
+ """Appends a DONT_CARE chunk to the sparse file.
+
+ The given number of bytes must be a multiple of the block size.
+
+ Arguments:
+ num_bytes: Size in number of bytes of the DONT_CARE chunk.
+
+ Raises
+ OSError: If ImageHandler was initialized in read-only mode.
+ """
+ assert num_bytes % self.block_size == 0
+
+ if self._read_only:
+ raise OSError('ImageHandler is in read-only mode.')
+
+ if not self.is_sparse:
+ self._image.seek(0, os.SEEK_END)
+ # This is more efficient that writing NUL bytes since it'll add
+ # a hole on file systems that support sparse files (native
+ # sparse, not Android sparse).
+ self._image.truncate(self._image.tell() + num_bytes)
+ self._read_header()
+ return
+
+ self._num_total_chunks += 1
+ self._num_total_blocks += num_bytes // self.block_size
+ self._update_chunks_and_blocks()
+
+ self._image.seek(self._sparse_end, os.SEEK_SET)
+ self._image.write(
+ struct.pack(
+ ImageChunk.FORMAT,
+ ImageChunk.TYPE_DONT_CARE,
+ 0, # Reserved
+ num_bytes // self.block_size,
+ struct.calcsize(ImageChunk.FORMAT)))
+ self._read_header()
+
+ def append_raw(self, data):
+ """Appends a RAW chunk to the sparse file.
+
+ The length of the given data must be a multiple of the block size.
+
+ Arguments:
+ data: Data to append as bytes.
+
+ Raises
+ OSError: If ImageHandler was initialized in read-only mode.
+ """
+ assert len(data) % self.block_size == 0
+
+ if self._read_only:
+ raise OSError('ImageHandler is in read-only mode.')
+
+ if not self.is_sparse:
+ self._image.seek(0, os.SEEK_END)
+ self._image.write(data)
+ self._read_header()
+ return
+
+ self._num_total_chunks += 1
+ self._num_total_blocks += len(data) // self.block_size
+ self._update_chunks_and_blocks()
+
+ self._image.seek(self._sparse_end, os.SEEK_SET)
+ self._image.write(
+ struct.pack(
+ ImageChunk.FORMAT,
+ ImageChunk.TYPE_RAW,
+ 0, # Reserved
+ len(data) // self.block_size,
+ len(data) + struct.calcsize(ImageChunk.FORMAT)))
+ self._image.write(data)
+ self._read_header()
+
+ def append_fill(self, fill_data, size):
+ """Appends a fill chunk to the sparse file.
+
+ The total length of the fill data must be a multiple of the block size.
+
+ Arguments:
+ fill_data: Fill data to append - must be four bytes.
+ size: Number of chunk - must be a multiple of four and the block size.
+
+ Raises
+ OSError: If ImageHandler was initialized in read-only mode.
+ """
+ assert len(fill_data) == 4
+ assert size % 4 == 0
+ assert size % self.block_size == 0
+
+ if self._read_only:
+ raise OSError('ImageHandler is in read-only mode.')
+
+ if not self.is_sparse:
+ self._image.seek(0, os.SEEK_END)
+ self._image.write(fill_data * (size // 4))
+ self._read_header()
+ return
+
+ self._num_total_chunks += 1
+ self._num_total_blocks += size // self.block_size
+ self._update_chunks_and_blocks()
+
+ self._image.seek(self._sparse_end, os.SEEK_SET)
+ self._image.write(
+ struct.pack(
+ ImageChunk.FORMAT,
+ ImageChunk.TYPE_FILL,
+ 0, # Reserved
+ size // self.block_size,
+ 4 + struct.calcsize(ImageChunk.FORMAT)))
+ self._image.write(fill_data)
+ self._read_header()
+
+ def seek(self, offset):
+ """Sets the cursor position for reading from unsparsified file.
+
+ Arguments:
+ offset: Offset to seek to from the beginning of the file.
+
+ Raises:
+ RuntimeError: If the given offset is negative.
+ """
+ if offset < 0:
+ raise RuntimeError(
+ 'Seeking with negative offset: {}'.format(offset))
+ self._file_pos = offset
+
+ def read(self, size):
+ """Reads data from the unsparsified file.
+
+ This method may return fewer than |size| bytes of data if the end
+ of the file was encountered.
+
+ The file cursor for reading is advanced by the number of bytes
+ read.
+
+ Arguments:
+ size: Number of bytes to read.
+
+ Returns:
+ The data as bytes.
+ """
+ if not self.is_sparse:
+ self._image.seek(self._file_pos)
+ data = self._image.read(size)
+ self._file_pos += len(data)
+ return data
+
+ # Iterate over all chunks.
+ chunk_idx = bisect.bisect_right(
+ self._chunk_output_offsets, self._file_pos) - 1
+ data = bytearray()
+ to_go = size
+ while to_go > 0:
+ chunk = self._chunks[chunk_idx]
+ chunk_pos_offset = self._file_pos - chunk.output_offset
+ chunk_pos_to_go = min(chunk.output_size - chunk_pos_offset, to_go)
+
+ if chunk.chunk_type == ImageChunk.TYPE_RAW:
+ self._image.seek(chunk.input_offset + chunk_pos_offset)
+ data.extend(self._image.read(chunk_pos_to_go))
+ elif chunk.chunk_type == ImageChunk.TYPE_FILL:
+ all_data = chunk.fill_data * (
+ chunk_pos_to_go // len(chunk.fill_data) + 2)
+ offset_mod = chunk_pos_offset % len(chunk.fill_data)
+ data.extend(all_data[offset_mod:(offset_mod + chunk_pos_to_go)])
+ else:
+ assert chunk.chunk_type == ImageChunk.TYPE_DONT_CARE
+ data.extend(b'\0' * chunk_pos_to_go)
+
+ to_go -= chunk_pos_to_go
+ self._file_pos += chunk_pos_to_go
+ chunk_idx += 1
+ # Generate partial read in case of EOF.
+ if chunk_idx >= len(self._chunks):
+ break
+
+ return bytes(data)
+
+ def tell(self):
+ """Returns the file cursor position for reading from unsparsified file.
+
+ Returns:
+ The file cursor position for reading.
+ """
+ return self._file_pos
+
+ def truncate(self, size):
+ """Truncates the unsparsified file.
+
+ Arguments:
+ size: Desired size of unsparsified file.
+
+ Raises:
+ ValueError: If desired size isn't a multiple of the block size.
+ OSError: If ImageHandler was initialized in read-only mode.
+ """
+ if self._read_only:
+ raise OSError('ImageHandler is in read-only mode.')
+
+ if not self.is_sparse:
+ self._image.truncate(size)
+ self._read_header()
+ return
+
+ if size % self.block_size != 0:
+ raise ValueError(
+ 'Cannot truncate to a size which is not a multiple '
+ 'of the block size')
+
+ if size == self.image_size:
+ # Trivial where there's nothing to do.
+ return
+
+ if size < self.image_size:
+ chunk_idx = bisect.bisect_right(
+ self._chunk_output_offsets, size) - 1
+ chunk = self._chunks[chunk_idx]
+ if chunk.output_offset != size:
+ # Truncation in the middle of a trunk - need to keep the chunk
+ # and modify it.
+ chunk_idx_for_update = chunk_idx + 1
+ num_to_keep = size - chunk.output_offset
+ assert num_to_keep % self.block_size == 0
+ if chunk.chunk_type == ImageChunk.TYPE_RAW:
+ truncate_at = (
+ chunk.chunk_offset +
+ struct.calcsize(ImageChunk.FORMAT) + num_to_keep)
+ data_sz = num_to_keep
+ elif chunk.chunk_type == ImageChunk.TYPE_FILL:
+ truncate_at = (
+ chunk.chunk_offset +
+ struct.calcsize(ImageChunk.FORMAT) + 4)
+ data_sz = 4
+ else:
+ assert chunk.chunk_type == ImageChunk.TYPE_DONT_CARE
+ truncate_at = chunk.chunk_offset + struct.calcsize(
+ ImageChunk.FORMAT)
+ data_sz = 0
+ chunk_sz = num_to_keep // self.block_size
+ total_sz = data_sz + struct.calcsize(ImageChunk.FORMAT)
+ self._image.seek(chunk.chunk_offset)
+ self._image.write(
+ struct.pack(
+ ImageChunk.FORMAT,
+ chunk.chunk_type,
+ 0, # Reserved
+ chunk_sz,
+ total_sz))
+ chunk.output_size = num_to_keep
+ else:
+ # Truncation at trunk boundary.
+ truncate_at = chunk.chunk_offset
+ chunk_idx_for_update = chunk_idx
+
+ self._num_total_chunks = chunk_idx_for_update
+ self._num_total_blocks = 0
+ for i in range(0, chunk_idx_for_update):
+ self._num_total_blocks += self._chunks[
+ i].output_size // self.block_size
+ self._update_chunks_and_blocks()
+ self._image.truncate(truncate_at)
+
+ # We've modified the file so re-read all data.
+ self._read_header()
+ else:
+ # Truncating to grow - just add a DONT_CARE section.
+ self.append_dont_care(size - self.image_size)
+
+
+class AvbDescriptor(object):
+ """Class for AVB descriptor.
+
+ See the |AvbDescriptor| C struct for more information.
+
+ Attributes:
+ tag: The tag identifying what kind of descriptor this is.
+ data: The data in the descriptor.
+ """
+
+ SIZE = 16
+ FORMAT_STRING = ('!QQ') # tag, num_bytes_following (descriptor header)
+
+ def __init__(self, data):
+ """Initializes a new property descriptor.
+
+ Arguments:
+ data: If not None, must be a bytearray().
+
+ Raises:
+ LookupError: If the given descriptor is malformed.
+ """
+ assert struct.calcsize(self.FORMAT_STRING) == self.SIZE
+
+ if data:
+ (self.tag, num_bytes_following) = (
+ struct.unpack(self.FORMAT_STRING, data[0:self.SIZE]))
+ self.data = data[self.SIZE:self.SIZE + num_bytes_following]
+ else:
+ self.tag = None
+ self.data = None
+
+ def print_desc(self, o):
+ """Print the descriptor.
+
+ Arguments:
+ o: The object to write the output to.
+ """
+ o.write(' Unknown descriptor:\n')
+ o.write(' Tag: {}\n'.format(self.tag))
+ if len(self.data) < 256:
+ o.write(
+ ' Data: {} ({} bytes)\n'.format(
+ repr(str(self.data)), len(self.data)))
+ else:
+ o.write(' Data: {} bytes\n'.format(len(self.data)))
+
+ def encode(self):
+ """Serializes the descriptor.
+
+ Returns:
+ A bytearray() with the descriptor data.
+ """
+ num_bytes_following = len(self.data)
+ nbf_with_padding = round_to_multiple(num_bytes_following, 8)
+ padding_size = nbf_with_padding - num_bytes_following
+ desc = struct.pack(self.FORMAT_STRING, self.tag, nbf_with_padding)
+ padding = struct.pack(str(padding_size) + 'x')
+ ret = desc + self.data + padding
+ return bytearray(ret)
+
+ def verify(
+ self, image_dir, image_ext, expected_chain_partitions_map,
+ image_containing_descriptor, accept_zeroed_hashtree):
+ """Verifies contents of the descriptor - used in verify_image sub-command.
+
+ Arguments:
+ image_dir: The directory of the file being verified.
+ 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.
+ accept_zeroed_hashtree: If True, don't fail if hashtree or FEC data is
+ zeroed out.
+
+ Returns:
+ True if the descriptor verifies, False otherwise.
+ """
+ # Deletes unused parameters to prevent pylint warning unused-argument.
+ del image_dir, image_ext, expected_chain_partitions_map
+ del image_containing_descriptor, accept_zeroed_hashtree
+
+ # Nothing to do.
+ return True
+
+
+class AvbPropertyDescriptor(AvbDescriptor):
+ """A class for property descriptors.
+
+ See the |AvbPropertyDescriptor| C struct for more information.
+
+ Attributes:
+ key: The key as string.
+ value: The value as bytes.
+ """
+
+ TAG = 0
+ SIZE = 32
+ FORMAT_STRING = (
+ '!QQ' # tag, num_bytes_following (descriptor header)
+ 'Q' # key size (bytes)
+ 'Q') # value size (bytes)
+
+ def __init__(self, data=None):
+ """Initializes a new property descriptor.
+
+ Arguments:
+ data: If not None, must be as bytes of size |SIZE|.
+
+ Raises:
+ LookupError: If the given descriptor is malformed.
+ """
+ super(AvbPropertyDescriptor, self).__init__(None)
+ assert struct.calcsize(self.FORMAT_STRING) == self.SIZE
+
+ if data:
+ (tag, num_bytes_following, key_size,
+ value_size) = struct.unpack(self.FORMAT_STRING, data[0:self.SIZE])
+ expected_size = round_to_multiple(
+ self.SIZE - 16 + key_size + 1 + value_size + 1, 8)
+ if tag != self.TAG or num_bytes_following != expected_size:
+ raise LookupError(
+ 'Given data does not look like a property '
+ 'descriptor.')
+ try:
+ self.key = data[self.SIZE:(self.SIZE +
+ key_size)].decode('utf-8')
+ except UnicodeDecodeError as e:
+ raise LookupError(
+ 'Key cannot be decoded as UTF-8: {}.'.format(e))
+ self.value = data[(self.SIZE + key_size +
+ 1):(self.SIZE + key_size + 1 + value_size)]
+ else:
+ self.key = ''
+ self.value = b''
+
+ def print_desc(self, o):
+ """Print the descriptor.
+
+ Arguments:
+ o: The object to write the output to.
+ """
+ # Go forward with python 3, bytes are represented with the 'b' prefix,
+ # e.g. b'foobar'. Thus, we trim off the 'b' to keep the print output
+ # the same between python 2 and python 3.
+ printable_value = repr(self.value)
+ if printable_value.startswith('b\''):
+ printable_value = printable_value[1:]
+
+ if len(self.value) < 256:
+ o.write(' Prop: {} -> {}\n'.format(self.key, printable_value))
+ else:
+ o.write(
+ ' Prop: {} -> ({} bytes)\n'.format(
+ self.key, len(self.value)))
+
+ def encode(self):
+ """Serializes the descriptor.
+
+ Returns:
+ The descriptor data as bytes.
+ """
+ key_encoded = self.key.encode('utf-8')
+ num_bytes_following = (
+ self.SIZE + len(key_encoded) + len(self.value) + 2 - 16)
+ nbf_with_padding = round_to_multiple(num_bytes_following, 8)
+ padding_size = nbf_with_padding - num_bytes_following
+ desc = struct.pack(
+ self.FORMAT_STRING, self.TAG, nbf_with_padding, len(key_encoded),
+ len(self.value))
+ ret = (
+ desc + key_encoded + b'\0' + self.value + b'\0' +
+ padding_size * b'\0')
+ return ret
+
+ def verify(
+ self, image_dir, image_ext, expected_chain_partitions_map,
+ image_containing_descriptor, accept_zeroed_hashtree):
+ """Verifies contents of the descriptor - used in verify_image sub-command.
+
+ Arguments:
+ image_dir: The directory of the file being verified.
+ 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.
+ accept_zeroed_hashtree: If True, don't fail if hashtree or FEC data is
+ zeroed out.
+
+ Returns:
+ True if the descriptor verifies, False otherwise.
+ """
+ # Nothing to do.
+ return True
+
+
+class AvbHashtreeDescriptor(AvbDescriptor):
+ """A class for hashtree descriptors.
+
+ See the |AvbHashtreeDescriptor| C struct for more information.
+
+ Attributes:
+ dm_verity_version: dm-verity version used.
+ image_size: Size of the image, after rounding up to |block_size|.
+ tree_offset: Offset of the hash tree in the file.
+ tree_size: Size of the tree.
+ data_block_size: Data block size.
+ hash_block_size: Hash block size.
+ fec_num_roots: Number of roots used for FEC (0 if FEC is not used).
+ fec_offset: Offset of FEC data (0 if FEC is not used).
+ fec_size: Size of FEC data (0 if FEC is not used).
+ hash_algorithm: Hash algorithm used as string.
+ partition_name: Partition name as string.
+ salt: Salt used as bytes.
+ root_digest: Root digest as bytes.
+ flags: Descriptor flags (see avb_hashtree_descriptor.h).
+ """
+
+ TAG = 1
+ RESERVED = 60
+ SIZE = 120 + RESERVED
+ FORMAT_STRING = (
+ '!QQ' # tag, num_bytes_following (descriptor header)
+ 'L' # dm-verity version used
+ 'Q' # image size (bytes)
+ 'Q' # tree offset (bytes)
+ 'Q' # tree size (bytes)
+ 'L' # data block size (bytes)
+ 'L' # hash block size (bytes)
+ 'L' # FEC number of roots
+ 'Q' # FEC offset (bytes)
+ 'Q' # FEC size (bytes)
+ '32s' # hash algorithm used
+ 'L' # partition name (bytes)
+ 'L' # salt length (bytes)
+ 'L' # root digest length (bytes)
+ 'L' + # flags
+ str(RESERVED) + 's') # reserved
+
+ def __init__(self, data=None):
+ """Initializes a new hashtree descriptor.
+
+ Arguments:
+ data: If not None, must be bytes of size |SIZE|.
+
+ Raises:
+ LookupError: If the given descriptor is malformed.
+ """
+ super(AvbHashtreeDescriptor, self).__init__(None)
+ assert struct.calcsize(self.FORMAT_STRING) == self.SIZE
+
+ if data:
+ (
+ tag, num_bytes_following, self.dm_verity_version,
+ self.image_size, self.tree_offset, self.tree_size,
+ self.data_block_size, self.hash_block_size, self.fec_num_roots,
+ self.fec_offset, self.fec_size, self.hash_algorithm,
+ partition_name_len, salt_len, root_digest_len, self.flags,
+ _) = struct.unpack(self.FORMAT_STRING, data[0:self.SIZE])
+ expected_size = round_to_multiple(
+ self.SIZE - 16 + partition_name_len + salt_len +
+ root_digest_len, 8)
+ if tag != self.TAG or num_bytes_following != expected_size:
+ raise LookupError(
+ 'Given data does not look like a hashtree '
+ 'descriptor.')
+ # Nuke NUL-bytes at the end.
+ self.hash_algorithm = self.hash_algorithm.rstrip(b'\0').decode(
+ 'ascii')
+ o = 0
+ try:
+ self.partition_name = data[(self.SIZE + o):(
+ self.SIZE + o + partition_name_len)].decode('utf-8')
+ except UnicodeDecodeError as e:
+ raise LookupError(
+ 'Partition name cannot be decoded as UTF-8: {}.'.format(e))
+ o += partition_name_len
+ self.salt = data[(self.SIZE + o):(self.SIZE + o + salt_len)]
+ o += salt_len
+ self.root_digest = data[(self.SIZE +
+ o):(self.SIZE + o + root_digest_len)]
+ if root_digest_len != len(hashlib.new(
+ self.hash_algorithm).digest()):
+ if root_digest_len != 0:
+ raise LookupError(
+ 'root_digest_len doesn\'t match hash algorithm')
+
+ else:
+ self.dm_verity_version = 0
+ self.image_size = 0
+ self.tree_offset = 0
+ self.tree_size = 0
+ self.data_block_size = 0
+ self.hash_block_size = 0
+ self.fec_num_roots = 0
+ self.fec_offset = 0
+ self.fec_size = 0
+ self.hash_algorithm = ''
+ self.partition_name = ''
+ self.salt = b''
+ self.root_digest = b''
+ self.flags = 0
+
+ def print_desc(self, o):
+ """Print the descriptor.
+
+ Arguments:
+ o: The object to write the output to.
+ """
+ o.write(' Hashtree descriptor:\n')
+ o.write(
+ ' Version of dm-verity: {}\n'.format(self.dm_verity_version))
+ o.write(
+ ' Image Size: {} bytes\n'.format(self.image_size))
+ o.write(' Tree Offset: {}\n'.format(self.tree_offset))
+ o.write(
+ ' Tree Size: {} bytes\n'.format(self.tree_size))
+ o.write(
+ ' Data Block Size: {} bytes\n'.format(
+ self.data_block_size))
+ o.write(
+ ' Hash Block Size: {} bytes\n'.format(
+ self.hash_block_size))
+ o.write(' FEC num roots: {}\n'.format(self.fec_num_roots))
+ o.write(' FEC offset: {}\n'.format(self.fec_offset))
+ o.write(' FEC size: {} bytes\n'.format(self.fec_size))
+ o.write(' Hash Algorithm: {}\n'.format(self.hash_algorithm))
+ o.write(' Partition Name: {}\n'.format(self.partition_name))
+ o.write(' Salt: {}\n'.format(self.salt.hex()))
+ o.write(
+ ' Root Digest: {}\n'.format(self.root_digest.hex()))
+ o.write(' Flags: {}\n'.format(self.flags))
+
+ def encode(self):
+ """Serializes the descriptor.
+
+ Returns:
+ The descriptor data as bytes.
+ """
+ hash_algorithm_encoded = self.hash_algorithm.encode('ascii')
+ partition_name_encoded = self.partition_name.encode('utf-8')
+ num_bytes_following = (
+ self.SIZE + len(partition_name_encoded) + len(self.salt) +
+ len(self.root_digest) - 16)
+ nbf_with_padding = round_to_multiple(num_bytes_following, 8)
+ padding_size = nbf_with_padding - num_bytes_following
+ desc = struct.pack(
+ self.FORMAT_STRING, self.TAG, nbf_with_padding,
+ self.dm_verity_version, self.image_size, self.tree_offset,
+ self.tree_size, self.data_block_size, self.hash_block_size,
+ self.fec_num_roots, self.fec_offset, self.fec_size,
+ hash_algorithm_encoded, len(partition_name_encoded), len(self.salt),
+ len(self.root_digest), self.flags, self.RESERVED * b'\0')
+ ret = (
+ desc + partition_name_encoded + self.salt + self.root_digest +
+ padding_size * b'\0')
+ return ret
+
+ def verify(
+ self, image_dir, image_ext, expected_chain_partitions_map,
+ image_containing_descriptor, accept_zeroed_hashtree):
+ """Verifies contents of the descriptor - used in verify_image sub-command.
+
+ Arguments:
+ image_dir: The directory of the file being verified.
+ 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.
+ accept_zeroed_hashtree: If True, don't fail if hashtree or FEC data is
+ zeroed out.
+
+ Returns:
+ True if the descriptor verifies, False otherwise.
+ """
+ if not self.partition_name:
+ image_filename = image_containing_descriptor.filename
+ image = image_containing_descriptor
+ else:
+ image_filename = os.path.join(
+ image_dir, self.partition_name + image_ext)
+ image = ImageHandler(image_filename, read_only=True)
+ # Generate the hashtree and checks that it matches what's in the file.
+ digest_size = len(hashlib.new(self.hash_algorithm).digest())
+ digest_padding = round_to_pow2(digest_size) - digest_size
+ (hash_level_offsets, tree_size) = calc_hash_level_offsets(
+ self.image_size, self.data_block_size, digest_size + digest_padding)
+ root_digest, hash_tree = generate_hash_tree(
+ image, self.image_size, self.data_block_size, self.hash_algorithm,
+ self.salt, digest_padding, hash_level_offsets, tree_size)
+ # The root digest must match unless it is not embedded in the descriptor.
+ if self.root_digest and root_digest != self.root_digest:
+ sys.stderr.write(
+ 'hashtree of {} does not match descriptor\n'.format(
+ image_filename))
+ return False
+ # ... also check that the on-disk hashtree matches
+ image.seek(self.tree_offset)
+ hash_tree_ondisk = image.read(self.tree_size)
+ is_zeroed = (self.tree_size
+ == 0) or (hash_tree_ondisk[0:8] == b'ZeRoHaSH')
+ if is_zeroed and accept_zeroed_hashtree:
+ print(
+ '{}: skipping verification since hashtree is zeroed and '
+ '--accept_zeroed_hashtree was given'.format(
+ self.partition_name))
+ else:
+ if hash_tree != hash_tree_ondisk:
+ sys.stderr.write(
+ 'hashtree of {} contains invalid data\n'.format(
+ image_filename))
+ return False
+ print(
+ '{}: Successfully verified {} hashtree of {} for image of {} bytes'
+ .format(
+ self.partition_name, self.hash_algorithm, image.filename,
+ self.image_size))
+ # TODO(zeuthen): we could also verify that the FEC stored in the image is
+ # correct but this a) currently requires the 'fec' binary; and b) takes a
+ # long time; and c) is not strictly needed for verification purposes as
+ # we've already verified the root hash.
+ return True
+
+
+class AvbHashDescriptor(AvbDescriptor):
+ """A class for hash descriptors.
+
+ See the |AvbHashDescriptor| C struct for more information.
+
+ Attributes:
+ image_size: Image size, in bytes.
+ hash_algorithm: Hash algorithm used as string.
+ partition_name: Partition name as string.
+ salt: Salt used as bytes.
+ digest: The hash value of salt and data combined as bytes.
+ flags: The descriptor flags (see avb_hash_descriptor.h).
+ """
+
+ TAG = 2
+ RESERVED = 60
+ SIZE = 72 + RESERVED
+ FORMAT_STRING = (
+ '!QQ' # tag, num_bytes_following (descriptor header)
+ 'Q' # image size (bytes)
+ '32s' # hash algorithm used
+ 'L' # partition name (bytes)
+ 'L' # salt length (bytes)
+ 'L' # digest length (bytes)
+ 'L' + # flags
+ str(RESERVED) + 's') # reserved
+
+ def __init__(self, data=None):
+ """Initializes a new hash descriptor.
+
+ Arguments:
+ data: If not None, must be bytes of size |SIZE|.
+
+ Raises:
+ LookupError: If the given descriptor is malformed.
+ """
+ super(AvbHashDescriptor, self).__init__(None)
+ assert struct.calcsize(self.FORMAT_STRING) == self.SIZE
+
+ if data:
+ (
+ tag, num_bytes_following, self.image_size, self.hash_algorithm,
+ partition_name_len, salt_len, digest_len, self.flags,
+ _) = struct.unpack(self.FORMAT_STRING, data[0:self.SIZE])
+ expected_size = round_to_multiple(
+ self.SIZE - 16 + partition_name_len + salt_len + digest_len, 8)
+ if tag != self.TAG or num_bytes_following != expected_size:
+ raise LookupError(
+ 'Given data does not look like a hash descriptor.')
+ # Nuke NUL-bytes at the end.
+ self.hash_algorithm = self.hash_algorithm.rstrip(b'\0').decode(
+ 'ascii')
+ o = 0
+ try:
+ self.partition_name = data[(self.SIZE + o):(
+ self.SIZE + o + partition_name_len)].decode('utf-8')
+ except UnicodeDecodeError as e:
+ raise LookupError(
+ 'Partition name cannot be decoded as UTF-8: {}.'.format(e))
+ o += partition_name_len
+ self.salt = data[(self.SIZE + o):(self.SIZE + o + salt_len)]
+ o += salt_len
+ self.digest = data[(self.SIZE + o):(self.SIZE + o + digest_len)]
+ if digest_len != len(hashlib.new(self.hash_algorithm).digest()):
+ if digest_len != 0:
+ raise LookupError(
+ 'digest_len doesn\'t match hash algorithm')
+
+ else:
+ self.image_size = 0
+ self.hash_algorithm = ''
+ self.partition_name = ''
+ self.salt = b''
+ self.digest = b''
+ self.flags = 0
+
+ def print_desc(self, o):
+ """Print the descriptor.
+
+ Arguments:
+ o: The object to write the output to.
+ """
+ o.write(' Hash descriptor:\n')
+ o.write(
+ ' Image Size: {} bytes\n'.format(self.image_size))
+ o.write(' Hash Algorithm: {}\n'.format(self.hash_algorithm))
+ o.write(' Partition Name: {}\n'.format(self.partition_name))
+ o.write(' Salt: {}\n'.format(self.salt.hex()))
+ o.write(' Digest: {}\n'.format(self.digest.hex()))
+ o.write(' Flags: {}\n'.format(self.flags))
+
+ def encode(self):
+ """Serializes the descriptor.
+
+ Returns:
+ The descriptor data as bytes.
+ """
+ hash_algorithm_encoded = self.hash_algorithm.encode('ascii')
+ partition_name_encoded = self.partition_name.encode('utf-8')
+ num_bytes_following = (
+ self.SIZE + len(partition_name_encoded) + len(self.salt) +
+ len(self.digest) - 16)
+ nbf_with_padding = round_to_multiple(num_bytes_following, 8)
+ padding_size = nbf_with_padding - num_bytes_following
+ desc = struct.pack(
+ self.FORMAT_STRING, self.TAG, nbf_with_padding, self.image_size,
+ hash_algorithm_encoded, len(partition_name_encoded), len(self.salt),
+ len(self.digest), self.flags, self.RESERVED * b'\0')
+ ret = (
+ desc + partition_name_encoded + self.salt + self.digest +
+ padding_size * b'\0')
+ return ret
+
+ def verify(
+ self, image_dir, image_ext, expected_chain_partitions_map,
+ image_containing_descriptor, accept_zeroed_hashtree):
+ """Verifies contents of the descriptor - used in verify_image sub-command.
+
+ Arguments:
+ image_dir: The directory of the file being verified.
+ 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.
+ accept_zeroed_hashtree: If True, don't fail if hashtree or FEC data is
+ zeroed out.
+
+ Returns:
+ True if the descriptor verifies, False otherwise.
+ """
+ if not self.partition_name:
+ image_filename = image_containing_descriptor.filename
+ image = image_containing_descriptor
+ else:
+ image_filename = os.path.join(
+ image_dir, self.partition_name + image_ext)
+ image = ImageHandler(image_filename, read_only=True)
+ data = image.read(self.image_size)
+ ha = hashlib.new(self.hash_algorithm)
+ ha.update(self.salt)
+ ha.update(data)
+ digest = ha.digest()
+ # The digest must match unless there is no digest in the descriptor.
+ if self.digest and digest != self.digest:
+ sys.stderr.write(
+ '{} digest of {} does not match digest in descriptor\n'.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,
+ self.image_size))
+ return True
+
+
+class AvbKernelCmdlineDescriptor(AvbDescriptor):
+ """A class for kernel command-line descriptors.
+
+ See the |AvbKernelCmdlineDescriptor| C struct for more information.
+
+ Attributes:
+ flags: Flags.
+ kernel_cmdline: The kernel command-line as string.
+ """
+
+ TAG = 3
+ SIZE = 24
+ FORMAT_STRING = (
+ '!QQ' # tag, num_bytes_following (descriptor header)
+ 'L' # flags
+ 'L') # cmdline length (bytes)
+
+ FLAGS_USE_ONLY_IF_HASHTREE_NOT_DISABLED = (1 << 0)
+ FLAGS_USE_ONLY_IF_HASHTREE_DISABLED = (1 << 1)
+
+ def __init__(self, data=None):
+ """Initializes a new kernel cmdline descriptor.
+
+ Arguments:
+ data: If not None, must be bytes of size |SIZE|.
+
+ Raises:
+ LookupError: If the given descriptor is malformed.
+ """
+ super(AvbKernelCmdlineDescriptor, self).__init__(None)
+ assert struct.calcsize(self.FORMAT_STRING) == self.SIZE
+
+ if data:
+ (tag, num_bytes_following, self.flags, kernel_cmdline_length) = (
+ struct.unpack(self.FORMAT_STRING, data[0:self.SIZE]))
+ expected_size = round_to_multiple(
+ self.SIZE - 16 + kernel_cmdline_length, 8)
+ if tag != self.TAG or num_bytes_following != expected_size:
+ raise LookupError(
+ 'Given data does not look like a kernel cmdline '
+ 'descriptor.')
+ # Nuke NUL-bytes at the end.
+ try:
+ self.kernel_cmdline = data[self.SIZE:(
+ self.SIZE + kernel_cmdline_length)].decode('utf-8')
+ except UnicodeDecodeError as e:
+ raise LookupError(
+ 'Kernel command-line cannot be decoded as UTF-8: {}.'.
+ format(e))
+ else:
+ self.flags = 0
+ self.kernel_cmdline = ''
+
+ def print_desc(self, o):
+ """Print the descriptor.
+
+ Arguments:
+ o: The object to write the output to.
+ """
+ o.write(' Kernel Cmdline descriptor:\n')
+ o.write(' Flags: {}\n'.format(self.flags))
+ o.write(
+ ' Kernel Cmdline: \'{}\'\n'.format(self.kernel_cmdline))
+
+ def encode(self):
+ """Serializes the descriptor.
+
+ Returns:
+ The descriptor data as bytes.
+ """
+ kernel_cmd_encoded = self.kernel_cmdline.encode('utf-8')
+ num_bytes_following = (self.SIZE + len(kernel_cmd_encoded) - 16)
+ nbf_with_padding = round_to_multiple(num_bytes_following, 8)
+ padding_size = nbf_with_padding - num_bytes_following
+ desc = struct.pack(
+ self.FORMAT_STRING, self.TAG, nbf_with_padding, self.flags,
+ len(kernel_cmd_encoded))
+ ret = desc + kernel_cmd_encoded + padding_size * b'\0'
+ return ret
+
+ def verify(
+ self, image_dir, image_ext, expected_chain_partitions_map,
+ image_containing_descriptor, accept_zeroed_hashtree):
+ """Verifies contents of the descriptor - used in verify_image sub-command.
+
+ Arguments:
+ image_dir: The directory of the file being verified.
+ 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.
+ accept_zeroed_hashtree: If True, don't fail if hashtree or FEC data is
+ zeroed out.
+
+ Returns:
+ True if the descriptor verifies, False otherwise.
+ """
+ # Nothing to verify.
+ return True
+
+
+class AvbChainPartitionDescriptor(AvbDescriptor):
+ """A class for chained partition descriptors.
+
+ See the |AvbChainPartitionDescriptor| C struct for more information.
+
+ Attributes:
+ rollback_index_location: The rollback index location to use.
+ partition_name: Partition name as string.
+ public_key: The public key as bytes.
+ """
+
+ TAG = 4
+ RESERVED = 64
+ SIZE = 28 + RESERVED
+ FORMAT_STRING = (
+ '!QQ' # tag, num_bytes_following (descriptor header)
+ 'L' # rollback_index_location
+ 'L' # partition_name_size (bytes)
+ 'L' + # public_key_size (bytes)
+ str(RESERVED) + 's') # reserved
+
+ def __init__(self, data=None):
+ """Initializes a new chain partition descriptor.
+
+ Arguments:
+ data: If not None, must be a bytearray of size |SIZE|.
+
+ Raises:
+ LookupError: If the given descriptor is malformed.
+ """
+ AvbDescriptor.__init__(self, None)
+ assert struct.calcsize(self.FORMAT_STRING) == self.SIZE
+
+ if data:
+ (
+ tag, num_bytes_following, self.rollback_index_location,
+ partition_name_len, public_key_len,
+ _) = struct.unpack(self.FORMAT_STRING, data[0:self.SIZE])
+ expected_size = round_to_multiple(
+ self.SIZE - 16 + partition_name_len + public_key_len, 8)
+ if tag != self.TAG or num_bytes_following != expected_size:
+ raise LookupError(
+ 'Given data does not look like a chain partition '
+ 'descriptor.')
+ o = 0
+ try:
+ self.partition_name = data[(self.SIZE + o):(
+ self.SIZE + o + partition_name_len)].decode('utf-8')
+ except UnicodeDecodeError as e:
+ raise LookupError(
+ 'Partition name cannot be decoded as UTF-8: {}.'.format(e))
+ o += partition_name_len
+ self.public_key = data[(self.SIZE +
+ o):(self.SIZE + o + public_key_len)]
+
+ else:
+ self.rollback_index_location = 0
+ self.partition_name = ''
+ self.public_key = b''
+
+ def print_desc(self, o):
+ """Print the descriptor.
+
+ Arguments:
+ o: The object to write the output to.
+ """
+ o.write(' Chain Partition descriptor:\n')
+ o.write(
+ ' Partition Name: {}\n'.format(self.partition_name))
+ o.write(
+ ' Rollback Index Location: {}\n'.format(
+ self.rollback_index_location))
+ # Just show the SHA1 of the key, for size reasons.
+ pubkey_digest = hashlib.sha1(self.public_key).hexdigest()
+ o.write(' Public key (sha1): {}\n'.format(pubkey_digest))
+
+ def encode(self):
+ """Serializes the descriptor.
+
+ Returns:
+ The descriptor data as bytes.
+ """
+ partition_name_encoded = self.partition_name.encode('utf-8')
+ num_bytes_following = (
+ self.SIZE + len(partition_name_encoded) + len(self.public_key) - 16)
+ nbf_with_padding = round_to_multiple(num_bytes_following, 8)
+ padding_size = nbf_with_padding - num_bytes_following
+ desc = struct.pack(
+ self.FORMAT_STRING, self.TAG, nbf_with_padding,
+ self.rollback_index_location, len(partition_name_encoded),
+ len(self.public_key), self.RESERVED * b'\0')
+ ret = desc + partition_name_encoded + self.public_key + padding_size * b'\0'
+ return ret
+
+ def verify(
+ self, image_dir, image_ext, expected_chain_partitions_map,
+ image_containing_descriptor, accept_zeroed_hashtree):
+ """Verifies contents of the descriptor - used in verify_image sub-command.
+
+ Arguments:
+ image_dir: The directory of the file being verified.
+ 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.
+ accept_zeroed_hashtree: If True, don't fail if hashtree or FEC data is
+ zeroed out.
+
+ Returns:
+ True if the descriptor verifies, False otherwise.
+ """
+ value = expected_chain_partitions_map.get(self.partition_name)
+ if not value:
+ sys.stderr.write(
+ 'No expected chain partition for partition {}. Use '
+ '--expected_chain_partition to specify expected '
+ 'contents or --follow_chain_partitions.\n'.format(
+ self.partition_name))
+ return False
+ rollback_index_location, pk_blob = value
+
+ if self.rollback_index_location != rollback_index_location:
+ sys.stderr.write(
+ 'Expected rollback_index_location {} does not '
+ 'match {} in descriptor for partition {}\n'.format(
+ rollback_index_location, self.rollback_index_location,
+ self.partition_name))
+ return False
+
+ if self.public_key != pk_blob:
+ sys.stderr.write(
+ 'Expected public key blob does not match public '
+ 'key blob in descriptor for partition {}\n'.format(
+ self.partition_name))
+ return False
+
+ print(
+ '{}: Successfully verified chain partition descriptor matches '
+ 'expected data'.format(self.partition_name))
+
+ return True
+
+
+DESCRIPTOR_CLASSES = [
+ AvbPropertyDescriptor, AvbHashtreeDescriptor, AvbHashDescriptor,
+ AvbKernelCmdlineDescriptor, AvbChainPartitionDescriptor
+]
+
+
+def parse_descriptors(data):
+ """Parses a blob of data into descriptors.
+
+ Arguments:
+ data: Encoded descriptors as bytes.
+
+ Returns:
+ A list of instances of objects derived from AvbDescriptor. For
+ unknown descriptors, the class AvbDescriptor is used.
+ """
+ o = 0
+ ret = []
+ while o < len(data):
+ tag, nb_following = struct.unpack('!2Q', data[o:o + 16])
+ if tag < len(DESCRIPTOR_CLASSES):
+ clazz = DESCRIPTOR_CLASSES[tag]
+ else:
+ clazz = AvbDescriptor
+ ret.append(clazz(data[o:o + 16 + nb_following]))
+ o += 16 + nb_following
+ return ret
+
+
+class AvbFooter(object):
+ """A class for parsing and writing footers.
+
+ Footers are stored at the end of partitions and point to where the
+ AvbVBMeta blob is located. They also contain the original size of
+ the image before AVB information was added.
+
+ Attributes:
+ magic: Magic for identifying the footer, see |MAGIC|.
+ version_major: The major version of avbtool that wrote the footer.
+ version_minor: The minor version of avbtool that wrote the footer.
+ original_image_size: Original image size.
+ vbmeta_offset: Offset of where the AvbVBMeta blob is stored.
+ vbmeta_size: Size of the AvbVBMeta blob.
+ """
+
+ MAGIC = b'AVBf'
+ SIZE = 64
+ RESERVED = 28
+ FOOTER_VERSION_MAJOR = AVB_FOOTER_VERSION_MAJOR
+ FOOTER_VERSION_MINOR = AVB_FOOTER_VERSION_MINOR
+ FORMAT_STRING = (
+ '!4s2L' # magic, 2 x version.
+ 'Q' # Original image size.
+ 'Q' # Offset of VBMeta blob.
+ 'Q' + # Size of VBMeta blob.
+ str(RESERVED) + 'x') # padding for reserved bytes
+
+ def __init__(self, data=None):
+ """Initializes a new footer object.
+
+ Arguments:
+ data: If not None, must be bytes of size 4096.
+
+ Raises:
+ LookupError: If the given footer is malformed.
+ struct.error: If the given data has no footer.
+ """
+ assert struct.calcsize(self.FORMAT_STRING) == self.SIZE
+
+ if data:
+ (
+ self.magic, self.version_major, self.version_minor,
+ self.original_image_size, self.vbmeta_offset,
+ self.vbmeta_size) = struct.unpack(self.FORMAT_STRING, data)
+ if self.magic != self.MAGIC:
+ raise LookupError('Given data does not look like a AVB footer.')
+ else:
+ self.magic = self.MAGIC
+ self.version_major = self.FOOTER_VERSION_MAJOR
+ self.version_minor = self.FOOTER_VERSION_MINOR
+ self.original_image_size = 0
+ self.vbmeta_offset = 0
+ self.vbmeta_size = 0
+
+ def encode(self):
+ """Serializes the footer.
+
+ Returns:
+ The footer as bytes.
+ """
+ return struct.pack(
+ self.FORMAT_STRING, self.magic, self.version_major,
+ self.version_minor, self.original_image_size, self.vbmeta_offset,
+ self.vbmeta_size)
+
+
+class AvbVBMetaHeader(object):
+ """A class for parsing and writing AVB vbmeta images.
+
+ The attributes correspond to the |AvbVBMetaImageHeader| struct defined in
+ avb_vbmeta_image.h.
+
+ Attributes:
+ magic: Four bytes equal to "AVB0" (AVB_MAGIC).
+ required_libavb_version_major: The major version of libavb required for this
+ header.
+ required_libavb_version_minor: The minor version of libavb required for this
+ header.
+ authentication_data_block_size: The size of the signature block.
+ auxiliary_data_block_size: The size of the auxiliary data block.
+ algorithm_type: The verification algorithm used, see |AvbAlgorithmType|
+ enum.
+ hash_offset: Offset into the "Authentication data" block of hash data.
+ hash_size: Length of the hash data.
+ signature_offset: Offset into the "Authentication data" block of signature
+ data.
+ signature_size: Length of the signature data.
+ public_key_offset: Offset into the "Auxiliary data" block of public key
+ data.
+ public_key_size: Length of the public key data.
+ public_key_metadata_offset: Offset into the "Auxiliary data" block of public
+ key metadata.
+ public_key_metadata_size: Length of the public key metadata. Must be set to
+ zero if there is no public key metadata.
+ descriptors_offset: Offset into the "Auxiliary data" block of descriptor
+ data.
+ descriptors_size: Length of descriptor data.
+ rollback_index: The rollback index which can be used to prevent rollback to
+ older versions.
+ flags: Flags from the AvbVBMetaImageFlags enumeration. This must be set to
+ zero if the vbmeta image is not a top-level image.
+ rollback_index_location: The location of the rollback index defined in this
+ header. Only valid for the main vbmeta. For chained partitions, the
+ rollback index location must be specified in the
+ AvbChainPartitionDescriptor and this value must be set to 0.
+ release_string: The release string from avbtool, e.g. "avbtool 1.0.0" or
+ "avbtool 1.0.0 xyz_board Git-234abde89". Is guaranteed to be NUL
+ terminated. Applications must not make assumptions about how this
+ string is formatted.
+ """
+ MAGIC = b'AVB0'
+ SIZE = 256
+
+ # Keep in sync with |reserved| field of |AvbVBMetaImageHeader|.
+ RESERVED = 80
+
+ # Keep in sync with |AvbVBMetaImageHeader|.
+ FORMAT_STRING = (
+ '!4s2L' # magic, 2 x version
+ '2Q' # 2 x block size
+ 'L' # algorithm type
+ '2Q' # offset, size (hash)
+ '2Q' # offset, size (signature)
+ '2Q' # offset, size (public key)
+ '2Q' # offset, size (public key metadata)
+ '2Q' # offset, size (descriptors)
+ 'Q' # rollback_index
+ 'L' # flags
+ 'L' # rollback_index_location
+ '47sx' + # NUL-terminated release string
+ str(RESERVED) + 'x') # padding for reserved bytes
+
+ def __init__(self, data=None):
+ """Initializes a new header object.
+
+ Arguments:
+ data: If not None, must be a bytearray of size 8192.
+
+ Raises:
+ Exception: If the given data is malformed.
+ """
+ assert struct.calcsize(self.FORMAT_STRING) == self.SIZE
+
+ if data:
+ (
+ self.magic, self.required_libavb_version_major,
+ self.required_libavb_version_minor,
+ self.authentication_data_block_size,
+ self.auxiliary_data_block_size, self.algorithm_type,
+ self.hash_offset, self.hash_size, self.signature_offset,
+ self.signature_size, self.public_key_offset,
+ self.public_key_size, self.public_key_metadata_offset,
+ self.public_key_metadata_size, self.descriptors_offset,
+ self.descriptors_size, self.rollback_index, self.flags,
+ self.rollback_index_location, release_string) = struct.unpack(
+ self.FORMAT_STRING, data)
+ # Nuke NUL-bytes at the end of the string.
+ if self.magic != self.MAGIC:
+ raise AvbError('Given image does not look like a vbmeta image.')
+ self.release_string = release_string.rstrip(b'\0').decode('utf-8')
+ else:
+ self.magic = self.MAGIC
+ # Start by just requiring version 1.0. Code that adds features
+ # in a future version can use bump_required_libavb_version_minor() to
+ # bump the minor.
+ self.required_libavb_version_major = AVB_VERSION_MAJOR
+ self.required_libavb_version_minor = 0
+ self.authentication_data_block_size = 0
+ self.auxiliary_data_block_size = 0
+ self.algorithm_type = 0
+ self.hash_offset = 0
+ self.hash_size = 0
+ self.signature_offset = 0
+ self.signature_size = 0
+ self.public_key_offset = 0
+ self.public_key_size = 0
+ self.public_key_metadata_offset = 0
+ self.public_key_metadata_size = 0
+ self.descriptors_offset = 0
+ self.descriptors_size = 0
+ self.rollback_index = 0
+ self.flags = 0
+ self.rollback_index_location = 0
+ self.release_string = get_release_string()
+
+ def bump_required_libavb_version_minor(self, minor):
+ """Function to bump required_libavb_version_minor.
+
+ Call this when writing data that requires a specific libavb
+ version to parse it.
+
+ Arguments:
+ minor: The minor version of libavb that has support for the feature.
+ """
+ self.required_libavb_version_minor = (
+ max(self.required_libavb_version_minor, minor))
+
+ def encode(self):
+ """Serializes the header.
+
+ Returns:
+ The header as bytes.
+ """
+ release_string_encoded = self.release_string.encode('utf-8')
+ return struct.pack(
+ self.FORMAT_STRING, self.magic, self.required_libavb_version_major,
+ self.required_libavb_version_minor,
+ self.authentication_data_block_size, self.auxiliary_data_block_size,
+ self.algorithm_type, self.hash_offset, self.hash_size,
+ self.signature_offset, self.signature_size, self.public_key_offset,
+ self.public_key_size, self.public_key_metadata_offset,
+ self.public_key_metadata_size, self.descriptors_offset,
+ self.descriptors_size, self.rollback_index, self.flags,
+ self.rollback_index_location, release_string_encoded)
+
+
+class Avb(object):
+ """Business logic for avbtool command-line tool."""
+
+ # Keep in sync with avb_ab_flow.h.
+ AB_FORMAT_NO_CRC = '!4sBB2xBBBxBBBx12x'
+ AB_MAGIC = b'\0AB0'
+ AB_MAJOR_VERSION = 1
+ AB_MINOR_VERSION = 0
+ AB_MISC_METADATA_OFFSET = 2048
+
+ # Constants for maximum metadata size. These are used to give
+ # meaningful errors if the value passed in via --partition_size is
+ # too small and when --calc_max_image_size is used. We use
+ # conservative figures.
+ MAX_VBMETA_SIZE = 64 * 1024
+ MAX_FOOTER_SIZE = 4096
+
+ def generate_test_image(self, output, image_size, start_byte):
+ """Generates a test image for testing avbtool with known content.
+
+ The content has following pattern: 0x00 0x01 0x02 .. 0xff 0x00 0x01 ..).
+
+ Arguments:
+ output: Write test image to this file.
+ image_size: The size of the requested file in bytes.
+ start_byte: The integer value of the start byte to use for pattern
+ generation.
+ """
+ pattern = bytearray(
+ [x & 0xFF for x in range(start_byte, start_byte + 256)])
+ buf = bytearray()
+ c = int(math.ceil(image_size / 256.0))
+ for _ in range(0, c):
+ buf.extend(pattern)
+ output.write(buf[0:image_size])
+
+ def extract_vbmeta_image(self, output, image_filename, padding_size):
+ """Implements the 'extract_vbmeta_image' command.
+
+ Arguments:
+ output: Write vbmeta struct to this file.
+ image_filename: File to extract vbmeta data from (with a footer).
+ padding_size: If not 0, pads output so size is a multiple of the number.
+
+ Raises:
+ AvbError: If there's no footer in the image.
+ """
+ image = ImageHandler(image_filename, read_only=True)
+ (footer, _, _, _) = self._parse_image(image)
+ if not footer:
+ raise AvbError('Given image does not have a footer.')
+
+ image.seek(footer.vbmeta_offset)
+ vbmeta_blob = image.read(footer.vbmeta_size)
+ output.write(vbmeta_blob)
+
+ if padding_size > 0:
+ padded_size = round_to_multiple(len(vbmeta_blob), padding_size)
+ padding_needed = padded_size - len(vbmeta_blob)
+ output.write(b'\0' * padding_needed)
+
+ def erase_footer(self, image_filename, keep_hashtree):
+ """Implements the 'erase_footer' command.
+
+ Arguments:
+ image_filename: File to erase a footer from.
+ keep_hashtree: If True, keep the hashtree and FEC around.
+
+ Raises:
+ AvbError: If there's no footer in the image.
+ """
+ image = ImageHandler(image_filename)
+ (footer, _, descriptors, _) = self._parse_image(image)
+ if not footer:
+ raise AvbError('Given image does not have a footer.')
+
+ new_image_size = None
+ if not keep_hashtree:
+ new_image_size = footer.original_image_size
+ else:
+ # If requested to keep the hashtree, search for a hashtree
+ # descriptor to figure out the location and size of the hashtree
+ # and FEC.
+ for desc in descriptors:
+ if isinstance(desc, AvbHashtreeDescriptor):
+ # The hashtree is always just following the main data so the
+ # new size is easily derived.
+ new_image_size = desc.tree_offset + desc.tree_size
+ # If the image has FEC codes, also keep those.
+ if desc.fec_offset > 0:
+ fec_end = desc.fec_offset + desc.fec_size
+ new_image_size = max(new_image_size, fec_end)
+ break
+ if not new_image_size:
+ raise AvbError(
+ 'Requested to keep hashtree but no hashtree '
+ 'descriptor was found.')
+
+ # And cut...
+ image.truncate(new_image_size)
+
+ def zero_hashtree(self, image_filename):
+ """Implements the 'zero_hashtree' command.
+
+ Arguments:
+ image_filename: File to zero hashtree and FEC data from.
+
+ Raises:
+ AvbError: If there's no footer in the image.
+ """
+ image = ImageHandler(image_filename)
+ (footer, _, descriptors, _) = self._parse_image(image)
+ if not footer:
+ raise AvbError('Given image does not have a footer.')
+
+ # Search for a hashtree descriptor to figure out the location and
+ # size of the hashtree and FEC.
+ ht_desc = None
+ for desc in descriptors:
+ if isinstance(desc, AvbHashtreeDescriptor):
+ ht_desc = desc
+ break
+
+ if not ht_desc:
+ raise AvbError('No hashtree descriptor was found.')
+
+ zero_ht_start_offset = ht_desc.tree_offset
+ zero_ht_num_bytes = ht_desc.tree_size
+ zero_fec_start_offset = None
+ zero_fec_num_bytes = 0
+ if ht_desc.fec_offset > 0:
+ if ht_desc.fec_offset != ht_desc.tree_offset + ht_desc.tree_size:
+ raise AvbError('Hash-tree and FEC data must be adjacent.')
+ zero_fec_start_offset = ht_desc.fec_offset
+ zero_fec_num_bytes = ht_desc.fec_size
+ zero_end_offset = (
+ zero_ht_start_offset + zero_ht_num_bytes + zero_fec_num_bytes)
+ image.seek(zero_end_offset)
+ data = image.read(image.image_size - zero_end_offset)
+
+ # Write zeroes all over hashtree and FEC, except for the first eight bytes
+ # where a magic marker - ZeroHaSH - is placed. Place these markers in the
+ # beginning of both hashtree and FEC. (That way, in the future we can add
+ # options to 'avbtool zero_hashtree' so as to zero out only either/or.)
+ #
+ # Applications can use these markers to detect that the hashtree and/or
+ # FEC needs to be recomputed.
+ image.truncate(zero_ht_start_offset)
+ data_zeroed_firstblock = b'ZeRoHaSH' + b'\0' * (image.block_size - 8)
+ image.append_raw(data_zeroed_firstblock)
+ image.append_fill(b'\0\0\0\0', zero_ht_num_bytes - image.block_size)
+ if zero_fec_start_offset:
+ image.append_raw(data_zeroed_firstblock)
+ image.append_fill(
+ b'\0\0\0\0', zero_fec_num_bytes - image.block_size)
+ image.append_raw(data)
+
+ def resize_image(self, image_filename, partition_size):
+ """Implements the 'resize_image' command.
+
+ Arguments:
+ image_filename: File with footer to resize.
+ partition_size: The new size of the image.
+
+ Raises:
+ AvbError: If there's no footer in the image.
+ """
+
+ 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))
+ (footer, _, _, _) = self._parse_image(image)
+ if not footer:
+ raise AvbError('Given image does not have a footer.')
+
+ # The vbmeta blob is always at the end of the data so resizing an
+ # image amounts to just moving the footer around.
+ vbmeta_end_offset = footer.vbmeta_offset + footer.vbmeta_size
+ if vbmeta_end_offset % image.block_size != 0:
+ vbmeta_end_offset += image.block_size - (
+ vbmeta_end_offset % image.block_size)
+
+ if partition_size < vbmeta_end_offset + 1 * image.block_size:
+ raise AvbError(
+ 'Requested size of {} is too small for an image '
+ 'of size {}.'.format(
+ partition_size, vbmeta_end_offset + 1 * image.block_size))
+
+ # Cut at the end of the vbmeta blob and insert a DONT_CARE chunk
+ # with enough bytes such that the final Footer block is at the end
+ # of partition_size.
+ image.truncate(vbmeta_end_offset)
+ image.append_dont_care(
+ partition_size - vbmeta_end_offset - 1 * image.block_size)
+
+ # Just reuse the same footer - only difference is that we're
+ # writing it in a different place.
+ footer_blob = footer.encode()
+ footer_blob_with_padding = (
+ b'\0' * (image.block_size - AvbFooter.SIZE) + footer_blob)
+ image.append_raw(footer_blob_with_padding)
+
+ def set_ab_metadata(self, misc_image, slot_data):
+ """Implements the 'set_ab_metadata' command.
+
+ The |slot_data| argument must be of the form 'A_priority:A_tries_remaining:
+ A_successful_boot:B_priority:B_tries_remaining:B_successful_boot'.
+
+ Arguments:
+ misc_image: The misc image to write to.
+ slot_data: Slot data as a string
+
+ Raises:
+ AvbError: If slot data is malformed.
+ """
+ tokens = slot_data.split(':')
+ if len(tokens) != 6:
+ raise AvbError('Malformed slot data "{}".'.format(slot_data))
+ a_priority = int(tokens[0])
+ a_tries_remaining = int(tokens[1])
+ a_success = int(tokens[2]) != 0
+ b_priority = int(tokens[3])
+ b_tries_remaining = int(tokens[4])
+ b_success = int(tokens[5]) != 0
+
+ ab_data_no_crc = struct.pack(
+ self.AB_FORMAT_NO_CRC, self.AB_MAGIC, self.AB_MAJOR_VERSION,
+ self.AB_MINOR_VERSION, a_priority, a_tries_remaining, a_success,
+ b_priority, b_tries_remaining, b_success)
+ # Force CRC to be unsigned, see https://bugs.python.org/issue4903 for why.
+ crc_value = binascii.crc32(ab_data_no_crc) & 0xffffffff
+ ab_data = ab_data_no_crc + struct.pack('!I', crc_value)
+ misc_image.seek(self.AB_MISC_METADATA_OFFSET)
+ misc_image.write(ab_data)
+
+ def info_image(self, image_filename, output, atx):
+ """Implements the 'info_image' command.
+
+ Arguments:
+ image_filename: Image file to get information from (file object).
+ output: Output file to write human-readable information to (file object).
+ atx: If True, show information about Android Things eXtension (ATX).
+ """
+ image = ImageHandler(image_filename, read_only=True)
+ o = output
+ (footer, header, descriptors, image_size) = self._parse_image(image)
+
+ # To show the SHA1 of the public key.
+ vbmeta_blob = self._load_vbmeta_blob(image)
+ key_offset = (
+ header.SIZE + header.authentication_data_block_size +
+ header.public_key_offset)
+ key_blob = vbmeta_blob[key_offset:key_offset + header.public_key_size]
+
+ if footer:
+ o.write(
+ 'Footer version: {}.{}\n'.format(
+ footer.version_major, footer.version_minor))
+ o.write('Image size: {} bytes\n'.format(image_size))
+ o.write(
+ 'Original image size: {} bytes\n'.format(
+ footer.original_image_size))
+ o.write(
+ 'VBMeta offset: {}\n'.format(footer.vbmeta_offset))
+ o.write(
+ 'VBMeta size: {} bytes\n'.format(
+ footer.vbmeta_size))
+ o.write('--\n')
+
+ (alg_name, _) = lookup_algorithm_by_type(header.algorithm_type)
+
+ o.write(
+ 'Minimum libavb version: {}.{}{}\n'.format(
+ header.required_libavb_version_major,
+ header.required_libavb_version_minor,
+ ' (Sparse)' if image.is_sparse else ''))
+ o.write(
+ 'Header Block: {} bytes\n'.format(AvbVBMetaHeader.SIZE))
+ o.write(
+ 'Authentication Block: {} bytes\n'.format(
+ header.authentication_data_block_size))
+ o.write(
+ 'Auxiliary Block: {} bytes\n'.format(
+ header.auxiliary_data_block_size))
+ if key_blob:
+ hexdig = hashlib.sha1(key_blob).hexdigest()
+ o.write('Public key (sha1): {}\n'.format(hexdig))
+ o.write('Algorithm: {}\n'.format(alg_name))
+ o.write('Rollback Index: {}\n'.format(header.rollback_index))
+ o.write('Flags: {}\n'.format(header.flags))
+ o.write(
+ 'Rollback Index Location: {}\n'.format(
+ header.rollback_index_location))
+ o.write(
+ 'Release String: \'{}\'\n'.format(header.release_string))
+
+ # Print descriptors.
+ num_printed = 0
+ o.write('Descriptors:\n')
+ for desc in descriptors:
+ desc.print_desc(o)
+ num_printed += 1
+ if num_printed == 0:
+ o.write(' (none)\n')
+
+ if atx and header.public_key_metadata_size:
+ o.write('Android Things eXtension (ATX):\n')
+ key_metadata_offset = (
+ header.SIZE + header.authentication_data_block_size +
+ header.public_key_metadata_offset)
+ key_metadata_blob = vbmeta_blob[
+ key_metadata_offset:key_metadata_offset +
+ header.public_key_metadata_size]
+ version, pik, psk = struct.unpack('<I1620s1620s', key_metadata_blob)
+ o.write(' Metadata version: {}\n'.format(version))
+
+ def print_atx_certificate(cert):
+ version, public_key, subject, usage, key_version, _signature = \
+ struct.unpack('<I1032s32s32sQ512s', cert)
+ o.write(' Version: {}\n'.format(version))
+ o.write(
+ ' Public key (sha1): {}\n'.format(
+ hashlib.sha1(public_key).hexdigest()))
+ o.write(
+ ' Subject: {}\n'.format(subject.hex()))
+ o.write(' Usage: {}\n'.format(usage.hex()))
+ o.write(' Key version: {}\n'.format(key_version))
+
+ o.write(' Product Intermediate Key:\n')
+ print_atx_certificate(pik)
+ o.write(' Product Signing Key:\n')
+ print_atx_certificate(psk)
+
+ def verify_image(
+ self, image_filename, key_path, expected_chain_partitions,
+ follow_chain_partitions, accept_zeroed_hashtree):
+ """Implements the 'verify_image' command.
+
+ Arguments:
+ image_filename: Image file to get information from (file object).
+ key_path: None or check that embedded public key matches key at given
+ path.
+ expected_chain_partitions: List of chain partitions to check or None.
+ follow_chain_partitions:
+ If True, will follows chain partitions even when not specified with
+ the --expected_chain_partition option
+ accept_zeroed_hashtree: If True, don't fail if hashtree or FEC data is
+ zeroed out.
+
+ Raises:
+ AvbError: If verification of the image fails.
+ """
+ expected_chain_partitions_map = {}
+ if expected_chain_partitions:
+ for cp in expected_chain_partitions:
+ cp_tokens = cp.split(':')
+ if len(cp_tokens) != 3:
+ raise AvbError(
+ 'Malformed chained partition "{}".'.format(cp))
+ partition_name = cp_tokens[0]
+ rollback_index_location = int(cp_tokens[1])
+ file_path = cp_tokens[2]
+ with open(file_path, 'rb') as f:
+ pk_blob = f.read()
+ expected_chain_partitions_map[partition_name] = (
+ rollback_index_location, pk_blob)
+
+ image_dir = os.path.dirname(image_filename)
+ image_ext = os.path.splitext(image_filename)[1]
+
+ key_blob = None
+ if key_path:
+ print(
+ 'Verifying image {} using key at {}'.format(
+ image_filename, key_path))
+ key_blob = RSAPublicKey(key_path).encode()
+ else:
+ print(
+ 'Verifying image {} using embedded public key'.format(
+ image_filename))
+
+ image = ImageHandler(image_filename, read_only=True)
+ (footer, header, descriptors, _) = self._parse_image(image)
+ offset = 0
+ if footer:
+ offset = footer.vbmeta_offset
+
+ image.seek(offset)
+ vbmeta_blob = image.read(
+ header.SIZE + header.authentication_data_block_size +
+ header.auxiliary_data_block_size)
+
+ alg_name, _ = lookup_algorithm_by_type(header.algorithm_type)
+ if not verify_vbmeta_signature(header, vbmeta_blob):
+ raise AvbError(
+ 'Signature check failed for {} vbmeta struct {}'.format(
+ alg_name, image_filename))
+
+ if key_blob:
+ # The embedded public key is in the auxiliary block at an offset.
+ key_offset = AvbVBMetaHeader.SIZE
+ key_offset += header.authentication_data_block_size
+ key_offset += header.public_key_offset
+ key_blob_in_vbmeta = vbmeta_blob[key_offset:key_offset +
+ header.public_key_size]
+ if key_blob != key_blob_in_vbmeta:
+ raise AvbError('Embedded public key does not match given key.')
+
+ if footer:
+ print(
+ 'vbmeta: Successfully verified footer and {} vbmeta struct in {}'
+ .format(alg_name, image.filename))
+ else:
+ print(
+ 'vbmeta: Successfully verified {} vbmeta struct in {}'.format(
+ alg_name, image.filename))
+
+ for desc in descriptors:
+ if (isinstance(desc, AvbChainPartitionDescriptor) and
+ follow_chain_partitions and
+ expected_chain_partitions_map.get(
+ desc.partition_name) is None):
+ # In this case we're processing a chain descriptor but don't have a
+ # --expect_chain_partition ... however --follow_chain_partitions was
+ # specified so we shouldn't error out in desc.verify().
+ print(
+ '{}: Chained but ROLLBACK_SLOT (which is {}) '
+ 'and KEY (which has sha1 {}) not specified'.format(
+ desc.partition_name, desc.rollback_index_location,
+ hashlib.sha1(desc.public_key).hexdigest()))
+ elif not desc.verify(image_dir, image_ext,
+ expected_chain_partitions_map, image,
+ accept_zeroed_hashtree):
+ raise AvbError('Error verifying descriptor.')
+ # Honor --follow_chain_partitions - add '--' to make the output more
+ # readable.
+ if (isinstance(desc, AvbChainPartitionDescriptor) and
+ follow_chain_partitions):
+ print('--')
+ chained_image_filename = os.path.join(
+ image_dir, desc.partition_name + image_ext)
+ self.verify_image(
+ chained_image_filename, key_path, None, False,
+ accept_zeroed_hashtree)
+
+ def print_partition_digests(self, image_filename, output, as_json):
+ """Implements the 'print_partition_digests' command.
+
+ Arguments:
+ image_filename: Image file to get information from (file object).
+ output: Output file to write human-readable information to (file object).
+ as_json: If True, print information as JSON
+
+ Raises:
+ AvbError: If getting the partition digests from the image fails.
+ """
+ image_dir = os.path.dirname(image_filename)
+ image_ext = os.path.splitext(image_filename)[1]
+ json_partitions = None
+ if as_json:
+ json_partitions = []
+ self._print_partition_digests(
+ image_filename, output, json_partitions, image_dir, image_ext)
+ if as_json:
+ output.write(json.dumps({'partitions': json_partitions}, indent=2))
+
+ def _print_partition_digests(
+ self, image_filename, output, json_partitions, image_dir,
+ image_ext):
+ """Helper for printing partitions.
+
+ Arguments:
+ image_filename: Image file to get information from (file object).
+ output: Output file to write human-readable information to (file object).
+ json_partitions: If not None, don't print to output, instead add partition
+ information to this list.
+ image_dir: The directory to use when looking for chained partition files.
+ image_ext: The extension to use for chained partition files.
+
+ Raises:
+ AvbError: If getting the partition digests from the image fails.
+ """
+ image = ImageHandler(image_filename, read_only=True)
+ (_, _, descriptors, _) = self._parse_image(image)
+
+ for desc in descriptors:
+ if isinstance(desc, AvbHashDescriptor):
+ digest = desc.digest.hex()
+ if json_partitions is not None:
+ json_partitions.append(
+ {
+ 'name': desc.partition_name,
+ 'digest': digest
+ })
+ else:
+ output.write('{}: {}\n'.format(desc.partition_name, digest))
+ elif isinstance(desc, AvbHashtreeDescriptor):
+ digest = desc.root_digest.hex()
+ if json_partitions is not None:
+ json_partitions.append(
+ {
+ 'name': desc.partition_name,
+ 'digest': digest
+ })
+ else:
+ output.write('{}: {}\n'.format(desc.partition_name, digest))
+ elif isinstance(desc, AvbChainPartitionDescriptor):
+ chained_image_filename = os.path.join(
+ image_dir, desc.partition_name + image_ext)
+ self._print_partition_digests(
+ chained_image_filename, output, json_partitions, image_dir,
+ image_ext)
+
+ def calculate_vbmeta_digest(self, image_filename, hash_algorithm, output):
+ """Implements the 'calculate_vbmeta_digest' command.
+
+ Arguments:
+ image_filename: Image file to get information from (file object).
+ hash_algorithm: Hash algorithm used.
+ output: Output file to write human-readable information to (file object).
+ """
+
+ image_dir = os.path.dirname(image_filename)
+ image_ext = os.path.splitext(image_filename)[1]
+
+ image = ImageHandler(image_filename, read_only=True)
+ (footer, header, descriptors, _) = self._parse_image(image)
+ offset = 0
+ if footer:
+ offset = footer.vbmeta_offset
+ size = (
+ header.SIZE + header.authentication_data_block_size +
+ header.auxiliary_data_block_size)
+ image.seek(offset)
+ vbmeta_blob = image.read(size)
+
+ hasher = hashlib.new(hash_algorithm)
+ hasher.update(vbmeta_blob)
+
+ for desc in descriptors:
+ if isinstance(desc, AvbChainPartitionDescriptor):
+ ch_image_filename = os.path.join(
+ image_dir, desc.partition_name + image_ext)
+ ch_image = ImageHandler(ch_image_filename, read_only=True)
+ (ch_footer, ch_header, _, _) = self._parse_image(ch_image)
+ ch_offset = 0
+ ch_size = (
+ ch_header.SIZE + ch_header.authentication_data_block_size +
+ ch_header.auxiliary_data_block_size)
+ if ch_footer:
+ ch_offset = ch_footer.vbmeta_offset
+ ch_image.seek(ch_offset)
+ ch_vbmeta_blob = ch_image.read(ch_size)
+ hasher.update(ch_vbmeta_blob)
+
+ digest = hasher.digest()
+ output.write('{}\n'.format(digest.hex()))
+
+ def calculate_kernel_cmdline(
+ self, image_filename, hashtree_disabled, output):
+ """Implements the 'calculate_kernel_cmdline' command.
+
+ Arguments:
+ image_filename: Image file to get information from (file object).
+ hashtree_disabled: If True, returns the cmdline for hashtree disabled.
+ output: Output file to write human-readable information to (file object).
+ """
+
+ image = ImageHandler(image_filename, read_only=True)
+ _, _, descriptors, _ = self._parse_image(image)
+
+ image_dir = os.path.dirname(image_filename)
+ image_ext = os.path.splitext(image_filename)[1]
+
+ cmdline_descriptors = []
+ for desc in descriptors:
+ if isinstance(desc, AvbChainPartitionDescriptor):
+ ch_image_filename = os.path.join(
+ image_dir, desc.partition_name + image_ext)
+ ch_image = ImageHandler(ch_image_filename, read_only=True)
+ _, _, ch_descriptors, _ = self._parse_image(ch_image)
+ for ch_desc in ch_descriptors:
+ if isinstance(ch_desc, AvbKernelCmdlineDescriptor):
+ cmdline_descriptors.append(ch_desc)
+ elif isinstance(desc, AvbKernelCmdlineDescriptor):
+ cmdline_descriptors.append(desc)
+
+ kernel_cmdline_snippets = []
+ for desc in cmdline_descriptors:
+ use_cmdline = True
+ if ((desc.flags & AvbKernelCmdlineDescriptor.
+ FLAGS_USE_ONLY_IF_HASHTREE_NOT_DISABLED) != 0):
+ if hashtree_disabled:
+ use_cmdline = False
+ if (desc.flags & AvbKernelCmdlineDescriptor.
+ FLAGS_USE_ONLY_IF_HASHTREE_DISABLED) != 0:
+ if not hashtree_disabled:
+ use_cmdline = False
+ if use_cmdline:
+ kernel_cmdline_snippets.append(desc.kernel_cmdline)
+ output.write(' '.join(kernel_cmdline_snippets))
+
+ def _parse_image(self, image):
+ """Gets information about an image.
+
+ The image can either be a vbmeta or an image with a footer.
+
+ Arguments:
+ image: An ImageHandler (vbmeta or footer) with a hashtree descriptor.
+
+ Returns:
+ A tuple where the first argument is a AvbFooter (None if there
+ is no footer on the image), the second argument is a
+ AvbVBMetaHeader, the third argument is a list of
+ AvbDescriptor-derived instances, and the fourth argument is the
+ size of |image|.
+
+ Raises:
+ AvbError: In case the image cannot be parsed.
+ """
+ assert isinstance(image, ImageHandler)
+ footer = None
+ image.seek(image.image_size - AvbFooter.SIZE)
+ try:
+ footer = AvbFooter(image.read(AvbFooter.SIZE))
+ except (LookupError, struct.error):
+ # Nope, just seek back to the start.
+ image.seek(0)
+
+ vbmeta_offset = 0
+ if footer:
+ vbmeta_offset = footer.vbmeta_offset
+
+ image.seek(vbmeta_offset)
+ h = AvbVBMetaHeader(image.read(AvbVBMetaHeader.SIZE))
+
+ auth_block_offset = vbmeta_offset + AvbVBMetaHeader.SIZE
+ aux_block_offset = auth_block_offset + h.authentication_data_block_size
+ desc_start_offset = aux_block_offset + h.descriptors_offset
+ image.seek(desc_start_offset)
+ descriptors = parse_descriptors(image.read(h.descriptors_size))
+
+ return footer, h, descriptors, image.image_size
+
+ def _load_vbmeta_blob(self, image):
+ """Gets the vbmeta struct and associated sections.
+
+ The image can either be a vbmeta.img or an image with a footer.
+
+ Arguments:
+ image: An ImageHandler (vbmeta or footer).
+
+ Returns:
+ A blob with the vbmeta struct and other sections.
+ """
+ assert isinstance(image, ImageHandler)
+ footer = None
+ image.seek(image.image_size - AvbFooter.SIZE)
+ try:
+ footer = AvbFooter(image.read(AvbFooter.SIZE))
+ except (LookupError, struct.error):
+ # Nope, just seek back to the start.
+ image.seek(0)
+
+ vbmeta_offset = 0
+ if footer:
+ vbmeta_offset = footer.vbmeta_offset
+
+ image.seek(vbmeta_offset)
+ h = AvbVBMetaHeader(image.read(AvbVBMetaHeader.SIZE))
+
+ image.seek(vbmeta_offset)
+ data_size = AvbVBMetaHeader.SIZE
+ data_size += h.authentication_data_block_size
+ data_size += h.auxiliary_data_block_size
+ return image.read(data_size)
+
+ def _get_cmdline_descriptors_for_hashtree_descriptor(self, ht):
+ """Generate kernel cmdline descriptors for dm-verity.
+
+ Arguments:
+ ht: A AvbHashtreeDescriptor
+
+ Returns:
+ A list with two AvbKernelCmdlineDescriptor with dm-verity kernel cmdline
+ instructions. There is one for when hashtree is not disabled and one for
+ when it is.
+
+ """
+ c = 'dm="1 vroot none ro 1,'
+ c += '0' # start
+ c += ' {}'.format((ht.image_size // 512)) # size (# sectors)
+ c += ' verity {}'.format(ht.dm_verity_version) # type and version
+ c += ' PARTUUID=$(ANDROID_SYSTEM_PARTUUID)' # data_dev
+ c += ' PARTUUID=$(ANDROID_SYSTEM_PARTUUID)' # hash_dev
+ c += ' {}'.format(ht.data_block_size) # data_block
+ c += ' {}'.format(ht.hash_block_size) # hash_block
+ c += ' {}'.format(ht.image_size // ht.data_block_size) # #blocks
+ c += ' {}'.format(ht.image_size // ht.data_block_size) # hash_offset
+ c += ' {}'.format(ht.hash_algorithm) # hash_alg
+ c += ' {}'.format(ht.root_digest.hex()) # root_digest
+ c += ' {}'.format(ht.salt.hex()) # salt
+ if ht.fec_num_roots > 0:
+ c += ' 10' # number of optional args
+ c += ' $(ANDROID_VERITY_MODE)'
+ c += ' ignore_zero_blocks'
+ c += ' use_fec_from_device PARTUUID=$(ANDROID_SYSTEM_PARTUUID)'
+ c += ' fec_roots {}'.format(ht.fec_num_roots)
+ # Note that fec_blocks is the size that FEC covers, *not* the
+ # size of the FEC data. Since we use FEC for everything up until
+ # the FEC data, it's the same as the offset.
+ c += ' fec_blocks {}'.format(ht.fec_offset // ht.data_block_size)
+ c += ' fec_start {}'.format(ht.fec_offset // ht.data_block_size)
+ else:
+ c += ' 2' # number of optional args
+ c += ' $(ANDROID_VERITY_MODE)'
+ c += ' ignore_zero_blocks'
+ c += '" root=/dev/dm-0'
+
+ # Now that we have the command-line, generate the descriptor.
+ desc = AvbKernelCmdlineDescriptor()
+ desc.kernel_cmdline = c
+ desc.flags = (
+ AvbKernelCmdlineDescriptor.FLAGS_USE_ONLY_IF_HASHTREE_NOT_DISABLED)
+
+ # The descriptor for when hashtree verification is disabled is a lot
+ # simpler - we just set the root to the partition.
+ desc_no_ht = AvbKernelCmdlineDescriptor()
+ desc_no_ht.kernel_cmdline = 'root=PARTUUID=$(ANDROID_SYSTEM_PARTUUID)'
+ desc_no_ht.flags = (
+ AvbKernelCmdlineDescriptor.FLAGS_USE_ONLY_IF_HASHTREE_DISABLED)
+
+ return [desc, desc_no_ht]
+
+ def _get_cmdline_descriptors_for_dm_verity(self, image):
+ """Generate kernel cmdline descriptors for dm-verity.
+
+ Arguments:
+ image: An ImageHandler (vbmeta or footer) with a hashtree descriptor.
+
+ Returns:
+ A list with two AvbKernelCmdlineDescriptor with dm-verity kernel cmdline
+ instructions. There is one for when hashtree is not disabled and one for
+ when it is.
+
+ Raises:
+ AvbError: If |image| doesn't have a hashtree descriptor.
+
+ """
+ (_, _, descriptors, _) = self._parse_image(image)
+
+ ht = None
+ for desc in descriptors:
+ if isinstance(desc, AvbHashtreeDescriptor):
+ ht = desc
+ break
+
+ if not ht:
+ raise AvbError('No hashtree descriptor in given image')
+
+ return self._get_cmdline_descriptors_for_hashtree_descriptor(ht)
+
+ def make_vbmeta_image(
+ self, output, chain_partitions, algorithm_name, key_path,
+ public_key_metadata_path, rollback_index, flags,
+ rollback_index_location, props, props_from_file, kernel_cmdlines,
+ setup_rootfs_from_kernel, include_descriptors_from_image,
+ signing_helper, signing_helper_with_files, release_string,
+ append_to_release_string, print_required_libavb_version,
+ padding_size):
+ """Implements the 'make_vbmeta_image' command.
+
+ Arguments:
+ output: File to write the image to.
+ chain_partitions: List of partitions to chain or None.
+ algorithm_name: Name of algorithm to use.
+ key_path: Path to key to use or None.
+ public_key_metadata_path: Path to public key metadata or None.
+ rollback_index: The rollback index to use.
+ flags: Flags value to use in the image.
+ rollback_index_location: Location of the main vbmeta rollback index.
+ props: Properties to insert (list of strings of the form 'key:value').
+ props_from_file: Properties to insert (list of strings 'key:<path>').
+ kernel_cmdlines: Kernel cmdlines to insert (list of strings).
+ setup_rootfs_from_kernel: None or file to generate from.
+ include_descriptors_from_image: List of file objects with descriptors.
+ signing_helper: Program which signs a hash and return signature.
+ signing_helper_with_files: Same as signing_helper but uses files instead.
+ release_string: None or avbtool release string to use instead of default.
+ append_to_release_string: None or string to append.
+ print_required_libavb_version: True to only print required libavb version.
+ padding_size: If not 0, pads output so size is a multiple of the number.
+
+ Raises:
+ AvbError: If a chained partition is malformed.
+ """
+ # If we're asked to calculate minimum required libavb version, we're done.
+ tmp_header = AvbVBMetaHeader()
+ if rollback_index_location > 0:
+ tmp_header.bump_required_libavb_version_minor(2)
+ if include_descriptors_from_image:
+ # Use the bump logic in AvbVBMetaHeader to calculate the max required
+ # version of all included descriptors.
+ for image in include_descriptors_from_image:
+ (_, image_header, _, _) = self._parse_image(
+ ImageHandler(image.name, read_only=True))
+ tmp_header.bump_required_libavb_version_minor(
+ image_header.required_libavb_version_minor)
+
+ if print_required_libavb_version:
+ print('1.{}'.format(tmp_header.required_libavb_version_minor))
+ return
+
+ if not output:
+ raise AvbError('No output file given')
+
+ descriptors = []
+ ht_desc_to_setup = None
+ vbmeta_blob = self._generate_vbmeta_blob(
+ algorithm_name, key_path, public_key_metadata_path, descriptors,
+ chain_partitions, rollback_index, flags, rollback_index_location,
+ props, props_from_file, kernel_cmdlines, setup_rootfs_from_kernel,
+ ht_desc_to_setup, include_descriptors_from_image, signing_helper,
+ signing_helper_with_files, release_string, append_to_release_string,
+ tmp_header.required_libavb_version_minor)
+
+ # Write entire vbmeta blob (header, authentication, auxiliary).
+ output.seek(0)
+ output.write(vbmeta_blob)
+
+ if padding_size > 0:
+ padded_size = round_to_multiple(len(vbmeta_blob), padding_size)
+ padding_needed = padded_size - len(vbmeta_blob)
+ output.write(b'\0' * padding_needed)
+
+ def _generate_vbmeta_blob(
+ self, algorithm_name, key_path, public_key_metadata_path,
+ descriptors, chain_partitions, rollback_index, flags,
+ rollback_index_location, props, props_from_file, kernel_cmdlines,
+ setup_rootfs_from_kernel, ht_desc_to_setup,
+ include_descriptors_from_image, signing_helper,
+ signing_helper_with_files, release_string, append_to_release_string,
+ required_libavb_version_minor):
+ """Generates a VBMeta blob.
+
+ This blob contains the header (struct AvbVBMetaHeader), the
+ authentication data block (which contains the hash and signature
+ for the header and auxiliary block), and the auxiliary block
+ (which contains descriptors, the public key used, and other data).
+
+ The |key| parameter can |None| only if the |algorithm_name| is
+ 'NONE'.
+
+ Arguments:
+ algorithm_name: The algorithm name as per the ALGORITHMS dict.
+ key_path: The path to the .pem file used to sign the blob.
+ public_key_metadata_path: Path to public key metadata or None.
+ descriptors: A list of descriptors to insert or None.
+ chain_partitions: List of partitions to chain or None.
+ rollback_index: The rollback index to use.
+ flags: Flags to use in the image.
+ rollback_index_location: Location of the main vbmeta rollback index.
+ props: Properties to insert (List of strings of the form 'key:value').
+ props_from_file: Properties to insert (List of strings 'key:<path>').
+ kernel_cmdlines: Kernel cmdlines to insert (list of strings).
+ setup_rootfs_from_kernel: None or file to generate
+ dm-verity kernel cmdline from.
+ ht_desc_to_setup: If not None, an AvbHashtreeDescriptor to
+ generate dm-verity kernel cmdline descriptors from.
+ include_descriptors_from_image: List of file objects for which
+ to insert descriptors from.
+ signing_helper: Program which signs a hash and return signature.
+ signing_helper_with_files: Same as signing_helper but uses files instead.
+ release_string: None or avbtool release string.
+ append_to_release_string: None or string to append.
+ required_libavb_version_minor: Use at least this required minor version.
+
+ Returns:
+ The VBMeta blob as bytes.
+
+ Raises:
+ Exception: If the |algorithm_name| is not found, if no key has
+ been given and the given algorithm requires one, or the key is
+ of the wrong size.
+ """
+ try:
+ alg = ALGORITHMS[algorithm_name]
+ except KeyError:
+ raise AvbError(
+ 'Unknown algorithm with name {}'.format(algorithm_name))
+
+ if not descriptors:
+ descriptors = []
+
+ h = AvbVBMetaHeader()
+ h.bump_required_libavb_version_minor(required_libavb_version_minor)
+
+ # Insert chained partition descriptors, if any
+ if chain_partitions:
+ used_locations = {rollback_index_location: True}
+ for cp in chain_partitions:
+ cp_tokens = cp.split(':')
+ if len(cp_tokens) != 3:
+ raise AvbError(
+ 'Malformed chained partition "{}".'.format(cp))
+ partition_name = cp_tokens[0]
+ chained_rollback_index_location = int(cp_tokens[1])
+ file_path = cp_tokens[2]
+ # Check that the same rollback location isn't being used by
+ # multiple chained partitions.
+ if used_locations.get(chained_rollback_index_location):
+ raise AvbError(
+ 'Rollback Index Location {} is already in use.'.format(
+ chained_rollback_index_location))
+ used_locations[chained_rollback_index_location] = True
+ desc = AvbChainPartitionDescriptor()
+ desc.partition_name = partition_name
+ desc.rollback_index_location = chained_rollback_index_location
+ if desc.rollback_index_location < 1:
+ raise AvbError(
+ 'Rollback index location must be 1 or larger.')
+ with open(file_path, 'rb') as f:
+ desc.public_key = f.read()
+ descriptors.append(desc)
+
+ # Descriptors.
+ encoded_descriptors = bytearray()
+ for desc in descriptors:
+ encoded_descriptors.extend(desc.encode())
+
+ # Add properties.
+ if props:
+ for prop in props:
+ idx = prop.find(':')
+ if idx == -1:
+ raise AvbError('Malformed property "{}".'.format(prop))
+ # pylint: disable=redefined-variable-type
+ desc = AvbPropertyDescriptor()
+ desc.key = prop[0:idx]
+ desc.value = prop[(idx + 1):].encode('utf-8')
+ encoded_descriptors.extend(desc.encode())
+ if props_from_file:
+ for prop in props_from_file:
+ idx = prop.find(':')
+ if idx == -1:
+ raise AvbError('Malformed property "{}".'.format(prop))
+ desc = AvbPropertyDescriptor()
+ desc.key = prop[0:idx]
+ file_path = prop[(idx + 1):]
+ with open(file_path, 'rb') as f:
+ # pylint: disable=attribute-defined-outside-init
+ desc.value = f.read()
+ encoded_descriptors.extend(desc.encode())
+
+ # Add AvbKernelCmdline descriptor for dm-verity from an image, if requested.
+ if setup_rootfs_from_kernel:
+ image_handler = ImageHandler(setup_rootfs_from_kernel.name)
+ cmdline_desc = self._get_cmdline_descriptors_for_dm_verity(
+ image_handler)
+ encoded_descriptors.extend(cmdline_desc[0].encode())
+ encoded_descriptors.extend(cmdline_desc[1].encode())
+
+ # Add AvbKernelCmdline descriptor for dm-verity from desc, if requested.
+ if ht_desc_to_setup:
+ cmdline_desc = self._get_cmdline_descriptors_for_hashtree_descriptor(
+ ht_desc_to_setup)
+ encoded_descriptors.extend(cmdline_desc[0].encode())
+ encoded_descriptors.extend(cmdline_desc[1].encode())
+
+ # Add kernel command-lines.
+ if kernel_cmdlines:
+ for i in kernel_cmdlines:
+ desc = AvbKernelCmdlineDescriptor()
+ desc.kernel_cmdline = i
+ encoded_descriptors.extend(desc.encode())
+
+ # Add descriptors from other images.
+ if include_descriptors_from_image:
+ descriptors_dict = dict()
+ for image in include_descriptors_from_image:
+ image_handler = ImageHandler(image.name, read_only=True)
+ (_, image_vbmeta_header, image_descriptors,
+ _) = self._parse_image(image_handler)
+ # Bump the required libavb version to support all included descriptors.
+ h.bump_required_libavb_version_minor(
+ image_vbmeta_header.required_libavb_version_minor)
+ for desc in image_descriptors:
+ # The --include_descriptors_from_image option is used in some setups
+ # with images A and B where both A and B contain a descriptor
+ # for a partition with the same name. Since it's not meaningful
+ # to include both descriptors, only include the last seen descriptor.
+ # See bug 76386656 for details.
+ if hasattr(desc, 'partition_name'):
+ key = type(desc).__name__ + '_' + desc.partition_name
+ descriptors_dict[key] = desc.encode()
+ else:
+ encoded_descriptors.extend(desc.encode())
+ for key in sorted(descriptors_dict):
+ encoded_descriptors.extend(descriptors_dict[key])
+
+ # Load public key metadata blob, if requested.
+ pkmd_blob = b''
+ if public_key_metadata_path:
+ with open(public_key_metadata_path, 'rb') as f:
+ pkmd_blob = f.read()
+
+ key = None
+ encoded_key = b''
+ if alg.public_key_num_bytes > 0:
+ if not key_path:
+ raise AvbError(
+ 'Key is required for algorithm {}'.format(algorithm_name))
+ encoded_key = RSAPublicKey(key_path).encode()
+ if len(encoded_key) != alg.public_key_num_bytes:
+ raise AvbError(
+ 'Key is wrong size for algorithm {}'.format(algorithm_name))
+
+ # Override release string, if requested.
+ if isinstance(release_string, str):
+ h.release_string = release_string
+
+ # Append to release string, if requested. Also insert a space before.
+ if isinstance(append_to_release_string, str):
+ h.release_string += ' ' + append_to_release_string
+
+ # For the Auxiliary data block, descriptors are stored at offset 0,
+ # followed by the public key, followed by the public key metadata blob.
+ h.auxiliary_data_block_size = round_to_multiple(
+ len(encoded_descriptors) + len(encoded_key) + len(pkmd_blob), 64)
+ h.descriptors_offset = 0
+ h.descriptors_size = len(encoded_descriptors)
+ h.public_key_offset = h.descriptors_size
+ h.public_key_size = len(encoded_key)
+ h.public_key_metadata_offset = h.public_key_offset + h.public_key_size
+ h.public_key_metadata_size = len(pkmd_blob)
+
+ # For the Authentication data block, the hash is first and then
+ # the signature.
+ h.authentication_data_block_size = round_to_multiple(
+ alg.hash_num_bytes + alg.signature_num_bytes, 64)
+ h.algorithm_type = alg.algorithm_type
+ h.hash_offset = 0
+ h.hash_size = alg.hash_num_bytes
+ # Signature offset and size - it's stored right after the hash
+ # (in Authentication data block).
+ h.signature_offset = alg.hash_num_bytes
+ h.signature_size = alg.signature_num_bytes
+
+ h.rollback_index = rollback_index
+ h.flags = flags
+ h.rollback_index_location = rollback_index_location
+
+ # Generate Header data block.
+ header_data_blob = h.encode()
+
+ # Generate Auxiliary data block.
+ aux_data_blob = bytearray()
+ aux_data_blob.extend(encoded_descriptors)
+ aux_data_blob.extend(encoded_key)
+ aux_data_blob.extend(pkmd_blob)
+ padding_bytes = h.auxiliary_data_block_size - len(aux_data_blob)
+ aux_data_blob.extend(b'\0' * padding_bytes)
+
+ # Calculate the hash.
+ binary_hash = b''
+ binary_signature = b''
+ if algorithm_name != 'NONE':
+ ha = hashlib.new(alg.hash_name)
+ ha.update(header_data_blob)
+ ha.update(aux_data_blob)
+ binary_hash = ha.digest()
+
+ # Calculate the signature.
+ rsa_key = RSAPublicKey(key_path)
+ data_to_sign = header_data_blob + bytes(aux_data_blob)
+ binary_signature = rsa_key.sign(
+ algorithm_name, data_to_sign, signing_helper,
+ signing_helper_with_files)
+
+ # Generate Authentication data block.
+ auth_data_blob = bytearray()
+ auth_data_blob.extend(binary_hash)
+ auth_data_blob.extend(binary_signature)
+ padding_bytes = h.authentication_data_block_size - len(auth_data_blob)
+ auth_data_blob.extend(b'\0' * padding_bytes)
+
+ return header_data_blob + bytes(auth_data_blob) + bytes(aux_data_blob)
+
+ def extract_public_key(self, key_path, output):
+ """Implements the 'extract_public_key' command.
+
+ Arguments:
+ key_path: The path to a RSA private key file.
+ output: The file to write to.
+
+ Raises:
+ AvbError: If the public key could not be extracted.
+ """
+ output.write(RSAPublicKey(key_path).encode())
+
+ def append_vbmeta_image(
+ self, image_filename, vbmeta_image_filename, partition_size):
+ """Implementation of the append_vbmeta_image command.
+
+ Arguments:
+ image_filename: File to add the footer to.
+ vbmeta_image_filename: File to get vbmeta struct from.
+ partition_size: Size of partition.
+
+ Raises:
+ AvbError: If an argument is incorrect or if appending VBMeta image fialed.
+ """
+ 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 there's already a footer, truncate the image to its original
+ # size. This way 'avbtool append_vbmeta_image' is idempotent.
+ if image.image_size >= AvbFooter.SIZE:
+ image.seek(image.image_size - AvbFooter.SIZE)
+ try:
+ footer = AvbFooter(image.read(AvbFooter.SIZE))
+ # Existing footer found. Just truncate.
+ original_image_size = footer.original_image_size
+ image.truncate(footer.original_image_size)
+ except (LookupError, struct.error):
+ original_image_size = image.image_size
+ else:
+ # Image size is too small to possibly contain a footer.
+ original_image_size = image.image_size
+
+ # If anything goes wrong from here-on, restore the image back to
+ # its original size.
+ try:
+ vbmeta_image_handler = ImageHandler(vbmeta_image_filename)
+ vbmeta_blob = self._load_vbmeta_blob(vbmeta_image_handler)
+
+ # If the image isn't sparse, its size might not be a multiple of
+ # the block size. This will screw up padding later so just grow it.
+ if image.image_size % image.block_size != 0:
+ assert not image.is_sparse
+ padding_needed = image.block_size - (
+ image.image_size % image.block_size)
+ image.truncate(image.image_size + padding_needed)
+
+ # The append_raw() method requires content with size being a
+ # multiple of |block_size| so add padding as needed. Also record
+ # where this is written to since we'll need to put that in the
+ # footer.
+ vbmeta_offset = image.image_size
+ padding_needed = (
+ round_to_multiple(len(vbmeta_blob), image.block_size) -
+ len(vbmeta_blob))
+ vbmeta_blob_with_padding = vbmeta_blob + b'\0' * padding_needed
+
+ # Append vbmeta blob and footer
+ image.append_raw(vbmeta_blob_with_padding)
+ vbmeta_end_offset = vbmeta_offset + len(vbmeta_blob_with_padding)
+
+ # 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 - vbmeta_end_offset - 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
+ # we'll write out an entire block.
+ footer = AvbFooter()
+ footer.original_image_size = original_image_size
+ footer.vbmeta_offset = vbmeta_offset
+ footer.vbmeta_size = len(vbmeta_blob)
+ footer_blob = footer.encode()
+ footer_blob_with_padding = (
+ b'\0' * (image.block_size - AvbFooter.SIZE) + footer_blob)
+ image.append_raw(footer_blob_with_padding)
+
+ except Exception as e:
+ # Truncate back to original size, then re-raise.
+ image.truncate(original_image_size)
+ raise AvbError('Appending VBMeta image failed: {}.'.format(e))
+
+ def add_hash_footer(
+ self, image_filename, partition_size, partition_name,
+ hash_algorithm, salt, chain_partitions, algorithm_name, key_path,
+ public_key_metadata_path, rollback_index, flags,
+ rollback_index_location, props, props_from_file, kernel_cmdlines,
+ setup_rootfs_from_kernel, include_descriptors_from_image,
+ calc_max_image_size, signing_helper, signing_helper_with_files,
+ release_string, append_to_release_string, output_vbmeta_image,
+ do_not_append_vbmeta_image, print_required_libavb_version,
+ use_persistent_digest, do_not_use_ab):
+ """Implementation of the add_hash_footer on unsparse images.
+
+ Arguments:
+ image_filename: File to add the footer to.
+ partition_size: Size of partition.
+ partition_name: Name of partition (without A/B suffix).
+ hash_algorithm: Hash algorithm to use.
+ salt: Salt to use as a hexadecimal string or None to use /dev/urandom.
+ chain_partitions: List of partitions to chain.
+ algorithm_name: Name of algorithm to use.
+ key_path: Path to key to use or None.
+ public_key_metadata_path: Path to public key metadata or None.
+ rollback_index: Rollback index.
+ flags: Flags value to use in the image.
+ rollback_index_location: Location of the main vbmeta rollback index.
+ props: Properties to insert (List of strings of the form 'key:value').
+ props_from_file: Properties to insert (List of strings 'key:<path>').
+ kernel_cmdlines: Kernel cmdlines to insert (list of strings).
+ setup_rootfs_from_kernel: None or file to generate
+ dm-verity kernel cmdline from.
+ include_descriptors_from_image: List of file objects for which
+ to insert descriptors from.
+ calc_max_image_size: Don't store the footer - instead calculate the
+ maximum image size leaving enough room for metadata with the
+ given |partition_size|.
+ signing_helper: Program which signs a hash and return signature.
+ signing_helper_with_files: Same as signing_helper but uses files instead.
+ release_string: None or avbtool release string.
+ append_to_release_string: None or string to append.
+ output_vbmeta_image: If not None, also write vbmeta struct to this file.
+ do_not_append_vbmeta_image: If True, don't append vbmeta struct.
+ print_required_libavb_version: True to only print required libavb version.
+ use_persistent_digest: Use a persistent digest on device.
+ do_not_use_ab: This partition does not use A/B.
+
+ Raises:
+ AvbError: If an argument is incorrect of if adding of hash_footer failed.
+ """
+ required_libavb_version_minor = 0
+ if use_persistent_digest or do_not_use_ab:
+ required_libavb_version_minor = 1
+ if rollback_index_location > 0:
+ required_libavb_version_minor = 2
+
+ # If we're asked to calculate minimum required libavb version, we're done.
+ if print_required_libavb_version:
+ print('1.{}'.format(required_libavb_version_minor))
+ return
+
+ # First, calculate the maximum image size such that an image
+ # this size + metadata (footer + vbmeta struct) fits in
+ # |partition_size|.
+ max_metadata_size = self.MAX_VBMETA_SIZE + self.MAX_FOOTER_SIZE
+ if partition_size < max_metadata_size:
+ raise AvbError(
+ 'Parition size of {} is too small. '
+ 'Needs to be at least {}'.format(
+ partition_size, max_metadata_size))
+ max_image_size = partition_size - max_metadata_size
+
+ # If we're asked to only calculate the maximum image size, we're done.
+ if calc_max_image_size:
+ print('{}'.format(max_image_size))
+ return
+
+ 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 there's already a footer, truncate the image to its original
+ # size. This way 'avbtool add_hash_footer' is idempotent (modulo
+ # salts).
+ if image.image_size >= AvbFooter.SIZE:
+ image.seek(image.image_size - AvbFooter.SIZE)
+ try:
+ footer = AvbFooter(image.read(AvbFooter.SIZE))
+ # Existing footer found. Just truncate.
+ original_image_size = footer.original_image_size
+ image.truncate(footer.original_image_size)
+ except (LookupError, struct.error):
+ original_image_size = image.image_size
+ else:
+ # Image size is too small to possibly contain a footer.
+ original_image_size = image.image_size
+
+ # If anything goes wrong from here-on, restore the image back to
+ # its original size.
+ try:
+ # 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))
+
+ digest_size = len(hashlib.new(hash_algorithm).digest())
+ if salt:
+ salt = binascii.unhexlify(salt)
+ elif salt is None and not use_persistent_digest:
+ # If salt is not explicitly specified, choose a hash that's the same
+ # size as the hash size. Don't populate a random salt if this
+ # descriptor is being created to use a persistent digest on device.
+ hash_size = digest_size
+ with open('/dev/urandom', 'rb') as f:
+ salt = f.read(hash_size)
+ else:
+ salt = b''
+
+ hasher = hashlib.new(hash_algorithm, salt)
+ # TODO(zeuthen): might want to read this in chunks to avoid
+ # memory pressure, then again, this is only supposed to be used
+ # on kernel/initramfs partitions. Possible optimization.
+ image.seek(0)
+ hasher.update(image.read(image.image_size))
+ digest = hasher.digest()
+
+ h_desc = AvbHashDescriptor()
+ h_desc.image_size = image.image_size
+ h_desc.hash_algorithm = hash_algorithm
+ h_desc.partition_name = partition_name
+ h_desc.salt = salt
+ h_desc.flags = 0
+ if do_not_use_ab:
+ h_desc.flags |= 1 # AVB_HASH_DESCRIPTOR_FLAGS_DO_NOT_USE_AB
+ if not use_persistent_digest:
+ h_desc.digest = digest
+
+ # Generate the VBMeta footer.
+ ht_desc_to_setup = None
+ vbmeta_blob = self._generate_vbmeta_blob(
+ algorithm_name, key_path, public_key_metadata_path, [h_desc],
+ chain_partitions, rollback_index, flags,
+ rollback_index_location, props, props_from_file,
+ kernel_cmdlines, setup_rootfs_from_kernel, ht_desc_to_setup,
+ include_descriptors_from_image, signing_helper,
+ signing_helper_with_files, release_string,
+ append_to_release_string, required_libavb_version_minor)
+
+ # Write vbmeta blob, if requested.
+ if output_vbmeta_image:
+ output_vbmeta_image.write(vbmeta_blob)
+
+ # Append vbmeta blob and footer, unless requested not to.
+ if not do_not_append_vbmeta_image:
+ # If the image isn't sparse, its size might not be a multiple of
+ # the block size. This will screw up padding later so just grow it.
+ if image.image_size % image.block_size != 0:
+ assert not image.is_sparse
+ padding_needed = image.block_size - (
+ image.image_size % image.block_size)
+ image.truncate(image.image_size + padding_needed)
+
+ # The append_raw() method requires content with size being a
+ # multiple of |block_size| so add padding as needed. Also record
+ # where this is written to since we'll need to put that in the
+ # footer.
+ vbmeta_offset = image.image_size
+ padding_needed = (
+ round_to_multiple(len(vbmeta_blob), image.block_size) -
+ len(vbmeta_blob))
+ vbmeta_blob_with_padding = vbmeta_blob + b'\0' * padding_needed
+
+ image.append_raw(vbmeta_blob_with_padding)
+ vbmeta_end_offset = vbmeta_offset + len(
+ vbmeta_blob_with_padding)
+
+ # 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 - vbmeta_end_offset - 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
+ # we'll write out an entire block.
+ footer = AvbFooter()
+ footer.original_image_size = original_image_size
+ footer.vbmeta_offset = vbmeta_offset
+ footer.vbmeta_size = len(vbmeta_blob)
+ footer_blob = footer.encode()
+ footer_blob_with_padding = (
+ b'\0' * (image.block_size - AvbFooter.SIZE) + footer_blob)
+ image.append_raw(footer_blob_with_padding)
+ except Exception as e:
+ # Truncate back to original size, then re-raise.
+ image.truncate(original_image_size)
+ raise AvbError('Adding hash_footer failed: {}.'.format(e))
+
+ def add_hashtree_footer(
+ self, image_filename, partition_size, partition_name, generate_fec,
+ fec_num_roots, hash_algorithm, block_size, salt, chain_partitions,
+ algorithm_name, key_path, public_key_metadata_path, rollback_index,
+ flags, rollback_index_location, props, props_from_file,
+ kernel_cmdlines, setup_rootfs_from_kernel,
+ setup_as_rootfs_from_kernel, include_descriptors_from_image,
+ calc_max_image_size, signing_helper, signing_helper_with_files,
+ release_string, append_to_release_string, output_vbmeta_image,
+ do_not_append_vbmeta_image, print_required_libavb_version,
+ use_persistent_root_digest, do_not_use_ab, no_hashtree):
+ """Implements the 'add_hashtree_footer' command.
+
+ See https://gitlab.com/cryptsetup/cryptsetup/wikis/DMVerity for
+ more information about dm-verity and these hashes.
+
+ Arguments:
+ image_filename: File to add the footer to.
+ 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.
+ hash_algorithm: Hash algorithm to use.
+ block_size: Block size to use.
+ salt: Salt to use as a hexadecimal string or None to use /dev/urandom.
+ chain_partitions: List of partitions to chain.
+ algorithm_name: Name of algorithm to use.
+ key_path: Path to key to use or None.
+ public_key_metadata_path: Path to public key metadata or None.
+ rollback_index: Rollback index.
+ flags: Flags value to use in the image.
+ rollback_index_location: Location of the main vbmeta rollback index.
+ props: Properties to insert (List of strings of the form 'key:value').
+ props_from_file: Properties to insert (List of strings 'key:<path>').
+ kernel_cmdlines: Kernel cmdlines to insert (list of strings).
+ setup_rootfs_from_kernel: None or file to generate
+ dm-verity kernel cmdline from.
+ setup_as_rootfs_from_kernel: If True, generate dm-verity kernel
+ cmdline to set up rootfs.
+ include_descriptors_from_image: List of file objects for which
+ to insert descriptors from.
+ calc_max_image_size: Don't store the hashtree or footer - instead
+ calculate the maximum image size leaving enough room for hashtree
+ and metadata with the given |partition_size|.
+ signing_helper: Program which signs a hash and return signature.
+ signing_helper_with_files: Same as signing_helper but uses files instead.
+ release_string: None or avbtool release string.
+ append_to_release_string: None or string to append.
+ output_vbmeta_image: If not None, also write vbmeta struct to this file.
+ do_not_append_vbmeta_image: If True, don't append vbmeta struct.
+ print_required_libavb_version: True to only print required libavb version.
+ use_persistent_root_digest: Use a persistent root digest on device.
+ do_not_use_ab: The partition does not use A/B.
+ no_hashtree: Do not append hashtree. Set size in descriptor as zero.
+
+ Raises:
+ AvbError: If an argument is incorrect or adding the hashtree footer
+ failed.
+ """
+ required_libavb_version_minor = 0
+ if use_persistent_root_digest or do_not_use_ab:
+ required_libavb_version_minor = 1
+ if rollback_index_location > 0:
+ required_libavb_version_minor = 2
+
+ # If we're asked to calculate minimum required libavb version, we're done.
+ if print_required_libavb_version:
+ print('1.{}'.format(required_libavb_version_minor))
+ return
+
+ digest_size = len(hashlib.new(hash_algorithm).digest())
+ digest_padding = round_to_pow2(digest_size) - digest_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 = 0
+ max_fec_size = 0
+ if not no_hashtree:
+ (_, max_tree_size) = calc_hash_level_offsets(
+ partition_size, block_size, digest_size + digest_padding)
+ 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:
+ print('{}'.format(max_image_size))
+ return
+
+ image = ImageHandler(image_filename)
+
+ 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))
+ elif 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
+ # (modulo salts).
+ if image.image_size >= AvbFooter.SIZE:
+ image.seek(image.image_size - AvbFooter.SIZE)
+ try:
+ footer = AvbFooter(image.read(AvbFooter.SIZE))
+ # Existing footer found. Just truncate.
+ original_image_size = footer.original_image_size
+ image.truncate(footer.original_image_size)
+ except (LookupError, struct.error):
+ original_image_size = image.image_size
+ else:
+ # Image size is too small to possibly contain a footer.
+ original_image_size = image.image_size
+
+ # If anything goes wrong from here-on, restore the image back to
+ # its original size.
+ try:
+ # Ensure image is multiple of block_size.
+ rounded_image_size = round_to_multiple(image.image_size, block_size)
+ if rounded_image_size > image.image_size:
+ image.append_raw('\0' * (rounded_image_size - image.image_size))
+
+ # If image size exceeds the maximum image size, fail.
+ 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 = binascii.unhexlify(salt)
+ elif salt is None and not use_persistent_root_digest:
+ # If salt is not explicitly specified, choose a hash that's the same
+ # size as the hash size. Don't populate a random salt if this
+ # descriptor is being created to use a persistent digest on device.
+ hash_size = digest_size
+ with open('/dev/urandom', 'rb') as f:
+ salt = f.read(hash_size)
+ else:
+ salt = b''
+
+ # Hashes are stored upside down so we need to calculate hash
+ # offsets in advance.
+ (hash_level_offsets, tree_size) = calc_hash_level_offsets(
+ image.image_size, block_size, digest_size + digest_padding)
+
+ # If the image isn't sparse, its size might not be a multiple of
+ # the block size. This will screw up padding later so just grow it.
+ if image.image_size % image.block_size != 0:
+ assert not image.is_sparse
+ padding_needed = image.block_size - (
+ image.image_size % image.block_size)
+ image.truncate(image.image_size + padding_needed)
+
+ # Generate the tree and add padding as needed.
+ tree_offset = image.image_size
+ root_digest, hash_tree = generate_hash_tree(
+ image, image.image_size, block_size, hash_algorithm, salt,
+ digest_padding, hash_level_offsets, tree_size)
+
+ # Generate HashtreeDescriptor with details about the tree we
+ # just generated.
+ if no_hashtree:
+ tree_size = 0
+ hash_tree = b''
+ ht_desc = AvbHashtreeDescriptor()
+ ht_desc.dm_verity_version = 1
+ ht_desc.image_size = image.image_size
+ ht_desc.tree_offset = tree_offset
+ ht_desc.tree_size = tree_size
+ ht_desc.data_block_size = block_size
+ ht_desc.hash_block_size = block_size
+ ht_desc.hash_algorithm = hash_algorithm
+ ht_desc.partition_name = partition_name
+ ht_desc.salt = salt
+ if do_not_use_ab:
+ ht_desc.flags |= 1 # AVB_HASHTREE_DESCRIPTOR_FLAGS_DO_NOT_USE_AB
+ if not use_persistent_root_digest:
+ ht_desc.root_digest = root_digest
+
+ # Write the hash tree
+ padding_needed = (
+ round_to_multiple(len(hash_tree), image.block_size) -
+ len(hash_tree))
+ hash_tree_with_padding = hash_tree + b'\0' * padding_needed
+ image.append_raw(hash_tree_with_padding)
+ len_hashtree_and_fec = len(hash_tree_with_padding)
+
+ # Generate FEC codes, if requested.
+ if generate_fec:
+ if no_hashtree:
+ fec_data = b''
+ else:
+ fec_data = generate_fec_data(image_filename, fec_num_roots)
+ padding_needed = (
+ round_to_multiple(len(fec_data), image.block_size) -
+ len(fec_data))
+ fec_data_with_padding = fec_data + b'\0' * padding_needed
+ fec_offset = image.image_size
+ image.append_raw(fec_data_with_padding)
+ len_hashtree_and_fec += len(fec_data_with_padding)
+ # Update the hashtree descriptor.
+ ht_desc.fec_num_roots = fec_num_roots
+ ht_desc.fec_offset = fec_offset
+ ht_desc.fec_size = len(fec_data)
+
+ ht_desc_to_setup = None
+ if setup_as_rootfs_from_kernel:
+ ht_desc_to_setup = ht_desc
+
+ # Generate the VBMeta footer and add padding as needed.
+ vbmeta_offset = tree_offset + len_hashtree_and_fec
+ vbmeta_blob = self._generate_vbmeta_blob(
+ algorithm_name, key_path, public_key_metadata_path, [ht_desc],
+ chain_partitions, rollback_index, flags,
+ rollback_index_location, props, props_from_file,
+ kernel_cmdlines, setup_rootfs_from_kernel, ht_desc_to_setup,
+ include_descriptors_from_image, signing_helper,
+ signing_helper_with_files, release_string,
+ append_to_release_string, required_libavb_version_minor)
+ padding_needed = (
+ round_to_multiple(len(vbmeta_blob), image.block_size) -
+ len(vbmeta_blob))
+ vbmeta_blob_with_padding = vbmeta_blob + b'\0' * padding_needed
+
+ # Write vbmeta blob, if requested.
+ if output_vbmeta_image:
+ output_vbmeta_image.write(vbmeta_blob)
+
+ # Append vbmeta blob and footer, unless requested not to.
+ if not do_not_append_vbmeta_image:
+ image.append_raw(vbmeta_blob_with_padding)
+
+ # Now insert a DONT_CARE chunk with enough bytes such that the
+ # final Footer block is at the end of partition_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
+ # we'll write out an entire block.
+ footer = AvbFooter()
+ footer.original_image_size = original_image_size
+ footer.vbmeta_offset = vbmeta_offset
+ footer.vbmeta_size = len(vbmeta_blob)
+ footer_blob = footer.encode()
+ footer_blob_with_padding = (
+ b'\0' * (image.block_size - AvbFooter.SIZE) + footer_blob)
+ image.append_raw(footer_blob_with_padding)
+
+ except Exception as e:
+ # Truncate back to original size, then re-raise.
+ image.truncate(original_image_size)
+ raise AvbError('Adding hashtree_footer failed: {}.'.format(e))
+
+ def make_atx_certificate(
+ self, output, authority_key_path, subject_key_path,
+ subject_key_version, subject, is_intermediate_authority, usage,
+ signing_helper, signing_helper_with_files):
+ """Implements the 'make_atx_certificate' command.
+
+ Android Things certificates are required for Android Things public key
+ metadata. They chain the vbmeta signing key for a particular product back to
+ a fused, permanent root key. These certificates are fixed-length and fixed-
+ format with the explicit goal of not parsing ASN.1 in bootloader code.
+
+ Arguments:
+ output: Certificate will be written to this file on success.
+ authority_key_path: A PEM file path with the authority private key.
+ If None, then a certificate will be created without a
+ signature. The signature can be created out-of-band
+ and appended.
+ subject_key_path: Path to a PEM or DER subject public key.
+ subject_key_version: A 64-bit version value. If this is None, the number
+ of seconds since the epoch is used.
+ subject: A subject identifier. For Product Signing Key certificates this
+ should be the same Product ID found in the permanent attributes.
+ is_intermediate_authority: True if the certificate is for an intermediate
+ authority.
+ usage: If not empty, overrides the cert usage with a hash of this value.
+ signing_helper: Program which signs a hash and returns the signature.
+ signing_helper_with_files: Same as signing_helper but uses files instead.
+
+ Raises:
+ AvbError: If there an error during signing.
+ """
+ signed_data = bytearray()
+ signed_data.extend(struct.pack('<I', 1)) # Format Version
+ signed_data.extend(RSAPublicKey(subject_key_path).encode())
+ hasher = hashlib.sha256()
+ hasher.update(subject)
+ signed_data.extend(hasher.digest())
+ if not usage:
+ usage = 'com.google.android.things.vboot'
+ if is_intermediate_authority:
+ usage += '.ca'
+ hasher = hashlib.sha256()
+ hasher.update(usage.encode('ascii'))
+ signed_data.extend(hasher.digest())
+ if subject_key_version is None:
+ subject_key_version = int(time.time())
+ signed_data.extend(struct.pack('<Q', subject_key_version))
+ signature = b''
+ if authority_key_path:
+ rsa_key = RSAPublicKey(authority_key_path)
+ algorithm_name = 'SHA512_RSA4096'
+ signature = rsa_key.sign(
+ algorithm_name, signed_data, signing_helper,
+ signing_helper_with_files)
+ output.write(signed_data)
+ output.write(signature)
+
+ def make_atx_permanent_attributes(
+ self, output, root_authority_key_path, product_id):
+ """Implements the 'make_atx_permanent_attributes' command.
+
+ Android Things permanent attributes are designed to be permanent for a
+ particular product and a hash of these attributes should be fused into
+ hardware to enforce this.
+
+ Arguments:
+ output: Attributes will be written to this file on success.
+ root_authority_key_path: Path to a PEM or DER public key for
+ the root authority.
+ product_id: A 16-byte Product ID.
+
+ Raises:
+ AvbError: If an argument is incorrect.
+ """
+ EXPECTED_PRODUCT_ID_SIZE = 16 # pylint: disable=invalid-name
+ if len(product_id) != EXPECTED_PRODUCT_ID_SIZE:
+ raise AvbError('Invalid Product ID length.')
+ output.write(struct.pack('<I', 1)) # Format Version
+ output.write(RSAPublicKey(root_authority_key_path).encode())
+ output.write(product_id)
+
+ def make_atx_metadata(
+ self, output, intermediate_key_certificate,
+ product_key_certificate):
+ """Implements the 'make_atx_metadata' command.
+
+ Android Things metadata are included in vbmeta images to facilitate
+ verification. The output of this command can be used as the
+ public_key_metadata argument to other commands.
+
+ Arguments:
+ output: Metadata will be written to this file on success.
+ intermediate_key_certificate: A certificate file as output by
+ make_atx_certificate with
+ is_intermediate_authority set to true.
+ product_key_certificate: A certificate file as output by
+ make_atx_certificate with
+ is_intermediate_authority set to false.
+
+ Raises:
+ AvbError: If an argument is incorrect.
+ """
+ EXPECTED_CERTIFICATE_SIZE = 1620 # pylint: disable=invalid-name
+ if len(intermediate_key_certificate) != EXPECTED_CERTIFICATE_SIZE:
+ raise AvbError('Invalid intermediate key certificate length.')
+ if len(product_key_certificate) != EXPECTED_CERTIFICATE_SIZE:
+ raise AvbError('Invalid product key certificate length.')
+ output.write(struct.pack('<I', 1)) # Format Version
+ output.write(intermediate_key_certificate)
+ output.write(product_key_certificate)
+
+ def make_atx_unlock_credential(
+ self, output, intermediate_key_certificate, unlock_key_certificate,
+ challenge_path, unlock_key_path, signing_helper,
+ signing_helper_with_files):
+ """Implements the 'make_atx_unlock_credential' command.
+
+ Android Things unlock credentials can be used to authorize the unlock of AVB
+ on a device. These credentials are presented to an Android Things bootloader
+ via the fastboot interface in response to a 16-byte challenge. This method
+ creates all fields of the credential except the challenge signature field
+ (which is the last field) and can optionally create the challenge signature
+ field as well if a challenge and the unlock_key_path is provided.
+
+ Arguments:
+ output: The credential will be written to this file on success.
+ intermediate_key_certificate: A certificate file as output by
+ make_atx_certificate with
+ is_intermediate_authority set to true.
+ unlock_key_certificate: A certificate file as output by
+ make_atx_certificate with
+ is_intermediate_authority set to false and the
+ usage set to
+ 'com.google.android.things.vboot.unlock'.
+ challenge_path: [optional] A path to the challenge to sign.
+ unlock_key_path: [optional] A PEM file path with the unlock private key.
+ signing_helper: Program which signs a hash and returns the signature.
+ signing_helper_with_files: Same as signing_helper but uses files instead.
+
+ Raises:
+ AvbError: If an argument is incorrect or an error occurs during signing.
+ """
+ EXPECTED_CERTIFICATE_SIZE = 1620 # pylint: disable=invalid-name
+ EXPECTED_CHALLENGE_SIZE = 16 # pylint: disable=invalid-name
+ if len(intermediate_key_certificate) != EXPECTED_CERTIFICATE_SIZE:
+ raise AvbError('Invalid intermediate key certificate length.')
+ if len(unlock_key_certificate) != EXPECTED_CERTIFICATE_SIZE:
+ raise AvbError('Invalid product key certificate length.')
+ challenge = b''
+ if challenge_path:
+ with open(challenge_path, 'rb') as f:
+ challenge = f.read()
+ if len(challenge) != EXPECTED_CHALLENGE_SIZE:
+ raise AvbError('Invalid unlock challenge length.')
+ output.write(struct.pack('<I', 1)) # Format Version
+ output.write(intermediate_key_certificate)
+ output.write(unlock_key_certificate)
+ if challenge_path and unlock_key_path:
+ rsa_key = RSAPublicKey(unlock_key_path)
+ algorithm_name = 'SHA512_RSA4096'
+ signature = rsa_key.sign(
+ algorithm_name, challenge, signing_helper,
+ signing_helper_with_files)
+ output.write(signature)
+
+
+def calc_hash_level_offsets(image_size, block_size, digest_size):
+ """Calculate the offsets of all the hash-levels in a Merkle-tree.
+
+ Arguments:
+ image_size: The size of the image to calculate a Merkle-tree for.
+ block_size: The block size, e.g. 4096.
+ digest_size: The size of each hash, e.g. 32 for SHA-256.
+
+ Returns:
+ A tuple where the first argument is an array of offsets and the
+ second is size of the tree, in bytes.
+ """
+ level_offsets = []
+ level_sizes = []
+ tree_size = 0
+
+ num_levels = 0
+ size = image_size
+ while size > block_size:
+ num_blocks = (size + block_size - 1) // block_size
+ level_size = round_to_multiple(num_blocks * digest_size, block_size)
+
+ level_sizes.append(level_size)
+ tree_size += level_size
+ num_levels += 1
+
+ size = level_size
+
+ for n in range(0, num_levels):
+ offset = 0
+ for m in range(n + 1, num_levels):
+ offset += level_sizes[m]
+ level_offsets.append(offset)
+
+ return level_offsets, tree_size
+
+
+# See system/extras/libfec/include/fec/io.h for these definitions.
+FEC_FOOTER_FORMAT = '<LLLLLQ32s'
+FEC_MAGIC = 0xfecfecfe
+
+
+def calc_fec_data_size(image_size, num_roots):
+ """Calculates how much space FEC data will take.
+
+ Arguments:
+ image_size: The size of the image.
+ num_roots: Number of roots.
+
+ Returns:
+ The number of bytes needed for FEC for an image of the given size
+ and with the requested number of FEC roots.
+
+ Raises:
+ ValueError: If output from the 'fec' tool is invalid.
+ """
+ p = subprocess.Popen(
+ ['fec', '--print-fec-size',
+ str(image_size), '--roots',
+ str(num_roots)],
+ stdout=subprocess.PIPE,
+ stderr=subprocess.PIPE)
+ (pout, perr) = p.communicate()
+ retcode = p.wait()
+ if retcode != 0:
+ raise ValueError('Error invoking fec: {}'.format(perr))
+ return int(pout)
+
+
+def generate_fec_data(image_filename, num_roots):
+ """Generate FEC codes for an image.
+
+ Arguments:
+ image_filename: The filename of the image.
+ num_roots: Number of roots.
+
+ Returns:
+ The FEC data blob as bytes.
+
+ Raises:
+ ValueError: If calling the 'fec' tool failed or the output is invalid.
+ """
+ with tempfile.NamedTemporaryFile() as fec_tmpfile:
+ try:
+ subprocess.check_call(
+ [
+ 'fec', '--encode', '--roots',
+ str(num_roots), image_filename, fec_tmpfile.name
+ ],
+ stderr=open(os.devnull, 'wb'))
+ except subprocess.CalledProcessError as e:
+ raise ValueError('Execution of \'fec\' tool failed: {}.'.format(e))
+ fec_data = fec_tmpfile.read()
+
+ footer_size = struct.calcsize(FEC_FOOTER_FORMAT)
+ footer_data = fec_data[-footer_size:]
+ (magic, _, _, num_roots, fec_size, _,
+ _) = struct.unpack(FEC_FOOTER_FORMAT, footer_data)
+ if magic != FEC_MAGIC:
+ raise ValueError('Unexpected magic in FEC footer')
+ return fec_data[0:fec_size]
+
+
+def generate_hash_tree(
+ image, image_size, block_size, hash_alg_name, salt, digest_padding,
+ hash_level_offsets, tree_size):
+ """Generates a Merkle-tree for a file.
+
+ Arguments:
+ image: The image, as a file.
+ image_size: The size of the image.
+ block_size: The block size, e.g. 4096.
+ hash_alg_name: The hash algorithm, e.g. 'sha256' or 'sha1'.
+ salt: The salt to use.
+ digest_padding: The padding for each digest.
+ hash_level_offsets: The offsets from calc_hash_level_offsets().
+ tree_size: The size of the tree, in number of bytes.
+
+ Returns:
+ A tuple where the first element is the top-level hash as bytes and the
+ second element is the hash-tree as bytes.
+ """
+ hash_ret = bytearray(tree_size)
+ hash_src_offset = 0
+ hash_src_size = image_size
+ level_num = 0
+ while hash_src_size > block_size:
+ level_output_list = []
+ remaining = hash_src_size
+ while remaining > 0:
+ hasher = hashlib.new(hash_alg_name, salt)
+ # Only read from the file for the first level - for subsequent
+ # levels, access the array we're building.
+ if level_num == 0:
+ image.seek(hash_src_offset + hash_src_size - remaining)
+ data = image.read(min(remaining, block_size))
+ else:
+ offset = hash_level_offsets[level_num -
+ 1] + hash_src_size - remaining
+ data = hash_ret[offset:offset + block_size]
+ hasher.update(data)
+
+ remaining -= len(data)
+ if len(data) < block_size:
+ hasher.update(b'\0' * (block_size - len(data)))
+ level_output_list.append(hasher.digest())
+ if digest_padding > 0:
+ level_output_list.append(b'\0' * digest_padding)
+
+ level_output = b''.join(level_output_list)
+
+ padding_needed = (
+ round_to_multiple(len(level_output), block_size) -
+ len(level_output))
+ level_output += b'\0' * padding_needed
+
+ # Copy level-output into resulting tree.
+ offset = hash_level_offsets[level_num]
+ hash_ret[offset:offset + len(level_output)] = level_output
+
+ # Continue on to the next level.
+ hash_src_size = len(level_output)
+ level_num += 1
+
+ hasher = hashlib.new(hash_alg_name, salt)
+ hasher.update(level_output)
+ return hasher.digest(), bytes(hash_ret)
+
+
+class AvbTool(object):
+ """Object for avbtool command-line tool."""
+
+ def __init__(self):
+ """Initializer method."""
+ self.avb = Avb()
+
+ def _add_common_args(self, sub_parser):
+ """Adds arguments used by several sub-commands.
+
+ Arguments:
+ sub_parser: The parser to add arguments to.
+ """
+ sub_parser.add_argument(
+ '--algorithm',
+ help='Algorithm to use (default: NONE)',
+ metavar='ALGORITHM',
+ default='NONE')
+ sub_parser.add_argument(
+ '--key',
+ help='Path to RSA private key file',
+ metavar='KEY',
+ required=False)
+ sub_parser.add_argument(
+ '--signing_helper',
+ help='Path to helper used for signing',
+ metavar='APP',
+ default=None,
+ required=False)
+ sub_parser.add_argument(
+ '--signing_helper_with_files',
+ help='Path to helper used for signing using files',
+ metavar='APP',
+ default=None,
+ required=False)
+ sub_parser.add_argument(
+ '--public_key_metadata',
+ help='Path to public key metadata file',
+ metavar='KEY_METADATA',
+ required=False)
+ sub_parser.add_argument(
+ '--rollback_index',
+ help='Rollback Index',
+ type=parse_number,
+ default=0)
+ sub_parser.add_argument(
+ '--rollback_index_location',
+ help='Location of main vbmeta Rollback Index',
+ type=parse_number,
+ default=0)
+ # This is used internally for unit tests. Do not include in --help output.
+ sub_parser.add_argument(
+ '--internal_release_string', help=argparse.SUPPRESS)
+ sub_parser.add_argument(
+ '--append_to_release_string',
+ help='Text to append to release string',
+ metavar='STR')
+ sub_parser.add_argument(
+ '--prop', help='Add property', metavar='KEY:VALUE', action='append')
+ sub_parser.add_argument(
+ '--prop_from_file',
+ help='Add property from file',
+ metavar='KEY:PATH',
+ action='append')
+ sub_parser.add_argument(
+ '--kernel_cmdline',
+ help='Add kernel cmdline',
+ metavar='CMDLINE',
+ action='append')
+ # TODO(zeuthen): the --setup_rootfs_from_kernel option used to be called
+ # --generate_dm_verity_cmdline_from_hashtree. Remove support for the latter
+ # at some future point.
+ sub_parser.add_argument(
+ '--setup_rootfs_from_kernel',
+ '--generate_dm_verity_cmdline_from_hashtree',
+ metavar='IMAGE',
+ help='Adds kernel cmdline to set up IMAGE',
+ type=argparse.FileType('rb'))
+ sub_parser.add_argument(
+ '--include_descriptors_from_image',
+ help='Include descriptors from image',
+ metavar='IMAGE',
+ action='append',
+ type=argparse.FileType('rb'))
+ sub_parser.add_argument(
+ '--print_required_libavb_version',
+ help=(
+ 'Don\'t store the footer - '
+ 'instead calculate the required libavb '
+ 'version for the given options.'),
+ action='store_true')
+ # These are only allowed from top-level vbmeta and boot-in-lieu-of-vbmeta.
+ sub_parser.add_argument(
+ '--chain_partition',
+ help='Allow signed integrity-data for partition',
+ metavar='PART_NAME:ROLLBACK_SLOT:KEY_PATH',
+ action='append')
+ sub_parser.add_argument(
+ '--flags', help='VBMeta flags', type=parse_number, default=0)
+ sub_parser.add_argument(
+ '--set_hashtree_disabled_flag',
+ help='Set the HASHTREE_DISABLED flag',
+ action='store_true')
+
+ def _add_common_footer_args(self, sub_parser):
+ """Adds arguments used by add_*_footer sub-commands.
+
+ Arguments:
+ sub_parser: The parser to add arguments to.
+ """
+ sub_parser.add_argument(
+ '--use_persistent_digest',
+ help='Use a persistent digest on device instead of '
+ 'storing the digest in the descriptor. This '
+ 'cannot be used with A/B so must be combined '
+ 'with --do_not_use_ab when an A/B suffix is '
+ 'expected at runtime.',
+ action='store_true')
+ sub_parser.add_argument(
+ '--do_not_use_ab',
+ help='The partition does not use A/B even when an '
+ 'A/B suffix is present. This must not be used '
+ 'for vbmeta or chained partitions.',
+ action='store_true')
+
+ def _fixup_common_args(self, args):
+ """Common fixups needed by subcommands.
+
+ Arguments:
+ args: Arguments to modify.
+
+ Returns:
+ The modified arguments.
+ """
+ if args.set_hashtree_disabled_flag:
+ args.flags |= AVB_VBMETA_IMAGE_FLAGS_HASHTREE_DISABLED
+ return args
+
+ def run(self, argv):
+ """Command-line processor.
+
+ Arguments:
+ argv: Pass sys.argv from main.
+ """
+ parser = argparse.ArgumentParser()
+ subparsers = parser.add_subparsers(title='subcommands')
+
+ sub_parser = subparsers.add_parser(
+ 'generate_test_image',
+ help=(
+ 'Generates a test image with a known pattern for testing: '
+ '0x00 0x01 0x02 ... 0xff 0x00 0x01 ...'))
+ sub_parser.add_argument(
+ '--image_size',
+ help='Size of image to generate.',
+ type=parse_number,
+ required=True)
+ sub_parser.add_argument(
+ '--start_byte',
+ help='Integer for the start byte of the pattern.',
+ type=parse_number,
+ default=0)
+ sub_parser.add_argument(
+ '--output',
+ help='Output file name.',
+ type=argparse.FileType('wb'),
+ default=sys.stdout)
+ sub_parser.set_defaults(func=self.generate_test_image)
+
+ sub_parser = subparsers.add_parser(
+ 'version', help='Prints version of avbtool.')
+ sub_parser.set_defaults(func=self.version)
+
+ sub_parser = subparsers.add_parser(
+ 'extract_public_key', help='Extract public key.')
+ sub_parser.add_argument(
+ '--key', help='Path to RSA private key file', required=True)
+ sub_parser.add_argument(
+ '--output',
+ help='Output file name',
+ type=argparse.FileType('wb'),
+ required=True)
+ sub_parser.set_defaults(func=self.extract_public_key)
+
+ sub_parser = subparsers.add_parser(
+ 'make_vbmeta_image', help='Makes a vbmeta image.')
+ sub_parser.add_argument(
+ '--output', help='Output file name', type=argparse.FileType('wb'))
+ sub_parser.add_argument(
+ '--padding_size',
+ metavar='NUMBER',
+ help='If non-zero, pads output with NUL bytes so '
+ 'its size is a multiple of NUMBER '
+ '(default: 0)',
+ type=parse_number,
+ default=0)
+ self._add_common_args(sub_parser)
+ sub_parser.set_defaults(func=self.make_vbmeta_image)
+
+ sub_parser = subparsers.add_parser(
+ 'add_hash_footer', help='Add hashes and footer to image.')
+ sub_parser.add_argument(
+ '--image',
+ help='Image to add hashes to',
+ type=argparse.FileType('rb+'))
+ sub_parser.add_argument(
+ '--partition_size', help='Partition size', type=parse_number)
+ sub_parser.add_argument(
+ '--partition_name', help='Partition name', default=None)
+ sub_parser.add_argument(
+ '--hash_algorithm',
+ help='Hash algorithm to use (default: sha256)',
+ default='sha256')
+ sub_parser.add_argument(
+ '--salt', help='Salt in hex (default: /dev/urandom)')
+ sub_parser.add_argument(
+ '--calc_max_image_size',
+ help=(
+ 'Don\'t store the footer - '
+ 'instead calculate the maximum image size '
+ 'leaving enough room for metadata with '
+ 'the given partition size.'),
+ action='store_true')
+ sub_parser.add_argument(
+ '--output_vbmeta_image',
+ help='Also write vbmeta struct to file',
+ type=argparse.FileType('wb'))
+ sub_parser.add_argument(
+ '--do_not_append_vbmeta_image',
+ help=('Do not append vbmeta struct or footer '
+ 'to the image'),
+ action='store_true')
+ self._add_common_args(sub_parser)
+ self._add_common_footer_args(sub_parser)
+ sub_parser.set_defaults(func=self.add_hash_footer)
+
+ sub_parser = subparsers.add_parser(
+ 'append_vbmeta_image', help='Append vbmeta image to image.')
+ sub_parser.add_argument(
+ '--image',
+ help='Image to append vbmeta blob to',
+ type=argparse.FileType('rb+'))
+ sub_parser.add_argument(
+ '--partition_size',
+ help='Partition size',
+ type=parse_number,
+ required=True)
+ sub_parser.add_argument(
+ '--vbmeta_image',
+ help='Image with vbmeta blob to append',
+ type=argparse.FileType('rb'))
+ sub_parser.set_defaults(func=self.append_vbmeta_image)
+
+ sub_parser = subparsers.add_parser(
+ 'add_hashtree_footer', help='Add hashtree and footer to image.')
+ sub_parser.add_argument(
+ '--image',
+ help='Image to add hashtree to',
+ type=argparse.FileType('rb+'))
+ sub_parser.add_argument(
+ '--partition_size',
+ help='Partition size',
+ default=0,
+ type=parse_number)
+ sub_parser.add_argument(
+ '--partition_name', help='Partition name', default='')
+ sub_parser.add_argument(
+ '--hash_algorithm',
+ help='Hash algorithm to use (default: sha1)',
+ default='sha1')
+ sub_parser.add_argument(
+ '--salt', help='Salt in hex (default: /dev/urandom)')
+ sub_parser.add_argument(
+ '--block_size',
+ help='Block size (default: 4096)',
+ type=parse_number,
+ default=4096)
+ # TODO(zeuthen): The --generate_fec option was removed when we
+ # moved to generating FEC by default. To avoid breaking existing
+ # users needing to transition we simply just print a warning below
+ # in add_hashtree_footer(). Remove this option and the warning at
+ # some point in the future.
+ sub_parser.add_argument(
+ '--generate_fec', help=argparse.SUPPRESS, action='store_true')
+ sub_parser.add_argument(
+ '--do_not_generate_fec',
+ help='Do not generate forward-error-correction codes',
+ action='store_true')
+ sub_parser.add_argument(
+ '--fec_num_roots',
+ help='Number of roots for FEC (default: 2)',
+ type=parse_number,
+ default=2)
+ sub_parser.add_argument(
+ '--calc_max_image_size',
+ help=(
+ 'Don\'t store the hashtree or footer - '
+ 'instead calculate the maximum image size '
+ 'leaving enough room for hashtree '
+ 'and metadata with the given partition '
+ 'size.'),
+ action='store_true')
+ sub_parser.add_argument(
+ '--output_vbmeta_image',
+ help='Also write vbmeta struct to file',
+ type=argparse.FileType('wb'))
+ sub_parser.add_argument(
+ '--do_not_append_vbmeta_image',
+ help=('Do not append vbmeta struct or footer '
+ 'to the image'),
+ action='store_true')
+ # This is different from --setup_rootfs_from_kernel insofar that
+ # it doesn't take an IMAGE, the generated cmdline will be for the
+ # hashtree we're adding.
+ sub_parser.add_argument(
+ '--setup_as_rootfs_from_kernel',
+ action='store_true',
+ help='Adds kernel cmdline for setting up rootfs')
+ sub_parser.add_argument(
+ '--no_hashtree', action='store_true', help='Do not append hashtree')
+ self._add_common_args(sub_parser)
+ self._add_common_footer_args(sub_parser)
+ sub_parser.set_defaults(func=self.add_hashtree_footer)
+
+ sub_parser = subparsers.add_parser(
+ 'erase_footer', help='Erase footer from an image.')
+ sub_parser.add_argument(
+ '--image',
+ help='Image with a footer',
+ type=argparse.FileType('rb+'),
+ required=True)
+ sub_parser.add_argument(
+ '--keep_hashtree',
+ help='Keep the hashtree and FEC in the image',
+ action='store_true')
+ sub_parser.set_defaults(func=self.erase_footer)
+
+ sub_parser = subparsers.add_parser(
+ 'zero_hashtree', help='Zero out hashtree and FEC data.')
+ sub_parser.add_argument(
+ '--image',
+ help='Image with a footer',
+ type=argparse.FileType('rb+'),
+ required=True)
+ sub_parser.set_defaults(func=self.zero_hashtree)
+
+ sub_parser = subparsers.add_parser(
+ 'extract_vbmeta_image',
+ help='Extracts vbmeta from an image with a footer.')
+ sub_parser.add_argument(
+ '--image',
+ help='Image with footer',
+ type=argparse.FileType('rb'),
+ required=True)
+ sub_parser.add_argument(
+ '--output', help='Output file name', type=argparse.FileType('wb'))
+ sub_parser.add_argument(
+ '--padding_size',
+ metavar='NUMBER',
+ help='If non-zero, pads output with NUL bytes so '
+ 'its size is a multiple of NUMBER '
+ '(default: 0)',
+ type=parse_number,
+ default=0)
+ sub_parser.set_defaults(func=self.extract_vbmeta_image)
+
+ sub_parser = subparsers.add_parser(
+ 'resize_image', help='Resize image with a footer.')
+ sub_parser.add_argument(
+ '--image',
+ help='Image with a footer',
+ type=argparse.FileType('rb+'),
+ required=True)
+ sub_parser.add_argument(
+ '--partition_size', help='New partition size', type=parse_number)
+ sub_parser.set_defaults(func=self.resize_image)
+
+ sub_parser = subparsers.add_parser(
+ 'info_image', help='Show information about vbmeta or footer.')
+ sub_parser.add_argument(
+ '--image',
+ help='Image to show information about',
+ type=argparse.FileType('rb'),
+ required=True)
+ sub_parser.add_argument(
+ '--output',
+ help='Write info to file',
+ type=argparse.FileType('wt'),
+ default=sys.stdout)
+ sub_parser.add_argument(
+ '--atx',
+ help=('Show information about Android Things '
+ 'eXtension (ATX).'),
+ action='store_true')
+ sub_parser.set_defaults(func=self.info_image)
+
+ sub_parser = subparsers.add_parser(
+ 'verify_image', help='Verify an image.')
+ sub_parser.add_argument(
+ '--image',
+ help='Image to verify',
+ type=argparse.FileType('rb'),
+ required=True)
+ sub_parser.add_argument(
+ '--key',
+ help='Check embedded public key matches KEY',
+ metavar='KEY',
+ required=False)
+ sub_parser.add_argument(
+ '--expected_chain_partition',
+ help='Expected chain partition',
+ metavar='PART_NAME:ROLLBACK_SLOT:KEY_PATH',
+ action='append')
+ sub_parser.add_argument(
+ '--follow_chain_partitions',
+ help=(
+ 'Follows chain partitions even when not '
+ 'specified with the --expected_chain_partition option'),
+ action='store_true')
+ sub_parser.add_argument(
+ '--accept_zeroed_hashtree',
+ help=('Accept images where the hashtree or FEC data is zeroed out'),
+ action='store_true')
+ sub_parser.set_defaults(func=self.verify_image)
+
+ sub_parser = subparsers.add_parser(
+ 'print_partition_digests', help='Prints partition digests.')
+ sub_parser.add_argument(
+ '--image',
+ help='Image to print partition digests from',
+ type=argparse.FileType('rb'),
+ required=True)
+ sub_parser.add_argument(
+ '--output',
+ help='Write info to file',
+ type=argparse.FileType('wt'),
+ default=sys.stdout)
+ sub_parser.add_argument(
+ '--json', help=('Print output as JSON'), action='store_true')
+ sub_parser.set_defaults(func=self.print_partition_digests)
+
+ sub_parser = subparsers.add_parser(
+ 'calculate_vbmeta_digest', help='Calculate vbmeta digest.')
+ sub_parser.add_argument(
+ '--image',
+ help='Image to calculate digest for',
+ type=argparse.FileType('rb'),
+ required=True)
+ sub_parser.add_argument(
+ '--hash_algorithm',
+ help='Hash algorithm to use (default: sha256)',
+ default='sha256')
+ sub_parser.add_argument(
+ '--output',
+ help='Write hex digest to file (default: stdout)',
+ type=argparse.FileType('wt'),
+ default=sys.stdout)
+ sub_parser.set_defaults(func=self.calculate_vbmeta_digest)
+
+ sub_parser = subparsers.add_parser(
+ 'calculate_kernel_cmdline', help='Calculate kernel cmdline.')
+ sub_parser.add_argument(
+ '--image',
+ help='Image to calculate kernel cmdline for',
+ type=argparse.FileType('rb'),
+ required=True)
+ sub_parser.add_argument(
+ '--hashtree_disabled',
+ help='Return the cmdline for hashtree disabled',
+ action='store_true')
+ sub_parser.add_argument(
+ '--output',
+ help='Write cmdline to file (default: stdout)',
+ type=argparse.FileType('wt'),
+ default=sys.stdout)
+ sub_parser.set_defaults(func=self.calculate_kernel_cmdline)
+
+ sub_parser = subparsers.add_parser(
+ 'set_ab_metadata', help='Set A/B metadata.')
+ sub_parser.add_argument(
+ '--misc_image',
+ help=(
+ 'The misc image to modify. If the image does '
+ 'not exist, it will be created.'),
+ type=argparse.FileType('r+b'),
+ required=True)
+ sub_parser.add_argument(
+ '--slot_data',
+ help=(
+ 'Slot data of the form "priority", '
+ '"tries_remaining", "sucessful_boot" for '
+ 'slot A followed by the same for slot B, '
+ 'separated by colons. The default value '
+ 'is 15:7:0:14:7:0.'),
+ default='15:7:0:14:7:0')
+ sub_parser.set_defaults(func=self.set_ab_metadata)
+
+ sub_parser = subparsers.add_parser(
+ 'make_atx_certificate',
+ help='Create an Android Things eXtension (ATX) certificate.')
+ sub_parser.add_argument(
+ '--output',
+ help='Write certificate to file',
+ type=argparse.FileType('wb'),
+ default=sys.stdout)
+ sub_parser.add_argument(
+ '--subject',
+ help=('Path to subject file'),
+ type=argparse.FileType('rb'),
+ required=True)
+ sub_parser.add_argument(
+ '--subject_key',
+ help=('Path to subject RSA public key file'),
+ type=argparse.FileType('rb'),
+ required=True)
+ sub_parser.add_argument(
+ '--subject_key_version',
+ help=('Version of the subject key'),
+ type=parse_number,
+ required=False)
+ sub_parser.add_argument(
+ '--subject_is_intermediate_authority',
+ help=('Generate an intermediate authority '
+ 'certificate'),
+ action='store_true')
+ sub_parser.add_argument(
+ '--usage',
+ help=('Override usage with a hash of the provided '
+ 'string'),
+ required=False)
+ sub_parser.add_argument(
+ '--authority_key',
+ help='Path to authority RSA private key file',
+ required=False)
+ sub_parser.add_argument(
+ '--signing_helper',
+ help='Path to helper used for signing',
+ metavar='APP',
+ default=None,
+ required=False)
+ sub_parser.add_argument(
+ '--signing_helper_with_files',
+ help='Path to helper used for signing using files',
+ metavar='APP',
+ default=None,
+ required=False)
+ sub_parser.set_defaults(func=self.make_atx_certificate)
+
+ sub_parser = subparsers.add_parser(
+ 'make_atx_permanent_attributes',
+ help='Create Android Things eXtension (ATX) permanent attributes.')
+ sub_parser.add_argument(
+ '--output',
+ help='Write attributes to file',
+ type=argparse.FileType('wb'),
+ default=sys.stdout)
+ sub_parser.add_argument(
+ '--root_authority_key',
+ help='Path to authority RSA public key file',
+ type=argparse.FileType('rb'),
+ required=True)
+ sub_parser.add_argument(
+ '--product_id',
+ help=('Path to Product ID file'),
+ type=argparse.FileType('rb'),
+ required=True)
+ sub_parser.set_defaults(func=self.make_atx_permanent_attributes)
+
+ sub_parser = subparsers.add_parser(
+ 'make_atx_metadata',
+ help='Create Android Things eXtension (ATX) metadata.')
+ sub_parser.add_argument(
+ '--output',
+ help='Write metadata to file',
+ type=argparse.FileType('wb'),
+ default=sys.stdout)
+ sub_parser.add_argument(
+ '--intermediate_key_certificate',
+ help='Path to intermediate key certificate file',
+ type=argparse.FileType('rb'),
+ required=True)
+ sub_parser.add_argument(
+ '--product_key_certificate',
+ help='Path to product key certificate file',
+ type=argparse.FileType('rb'),
+ required=True)
+ sub_parser.set_defaults(func=self.make_atx_metadata)
+
+ sub_parser = subparsers.add_parser(
+ 'make_atx_unlock_credential',
+ help='Create an Android Things eXtension (ATX) unlock credential.')
+ sub_parser.add_argument(
+ '--output',
+ help='Write credential to file',
+ type=argparse.FileType('wb'),
+ default=sys.stdout)
+ sub_parser.add_argument(
+ '--intermediate_key_certificate',
+ help='Path to intermediate key certificate file',
+ type=argparse.FileType('rb'),
+ required=True)
+ sub_parser.add_argument(
+ '--unlock_key_certificate',
+ help='Path to unlock key certificate file',
+ type=argparse.FileType('rb'),
+ required=True)
+ sub_parser.add_argument(
+ '--challenge',
+ help='Path to the challenge to sign (optional). If '
+ 'this is not provided the challenge signature '
+ 'field is omitted and can be concatenated '
+ 'later.',
+ required=False)
+ sub_parser.add_argument(
+ '--unlock_key',
+ help='Path to unlock key (optional). Must be '
+ 'provided if using --challenge.',
+ required=False)
+ sub_parser.add_argument(
+ '--signing_helper',
+ help='Path to helper used for signing',
+ metavar='APP',
+ default=None,
+ required=False)
+ sub_parser.add_argument(
+ '--signing_helper_with_files',
+ help='Path to helper used for signing using files',
+ metavar='APP',
+ default=None,
+ required=False)
+ sub_parser.set_defaults(func=self.make_atx_unlock_credential)
+
+ args = parser.parse_args(argv[1:])
+ try:
+ args.func(args)
+ except AttributeError:
+ # This error gets raised when the command line tool is called without any
+ # arguments. It mimics the original Python 2 behavior.
+ parser.print_usage()
+ print('avbtool: error: too few arguments')
+ sys.exit(2)
+ except AvbError as e:
+ sys.stderr.write('{}: {}\n'.format(argv[0], str(e)))
+ sys.exit(1)
+
+ def version(self, _):
+ """Implements the 'version' sub-command."""
+ print(get_release_string())
+
+ def generate_test_image(self, args):
+ """Implements the 'generate_test_image' sub-command."""
+ self.avb.generate_test_image(
+ args.output, args.image_size, args.start_byte)
+
+ def extract_public_key(self, args):
+ """Implements the 'extract_public_key' sub-command."""
+ self.avb.extract_public_key(args.key, args.output)
+
+ def make_vbmeta_image(self, args):
+ """Implements the 'make_vbmeta_image' sub-command."""
+ args = self._fixup_common_args(args)
+ self.avb.make_vbmeta_image(
+ args.output, args.chain_partition, args.algorithm, args.key,
+ args.public_key_metadata, args.rollback_index, args.flags,
+ args.rollback_index_location, args.prop, args.prop_from_file,
+ args.kernel_cmdline, args.setup_rootfs_from_kernel,
+ args.include_descriptors_from_image, args.signing_helper,
+ args.signing_helper_with_files, args.internal_release_string,
+ args.append_to_release_string, args.print_required_libavb_version,
+ args.padding_size)
+
+ def append_vbmeta_image(self, args):
+ """Implements the 'append_vbmeta_image' sub-command."""
+ self.avb.append_vbmeta_image(
+ args.image.name, args.vbmeta_image.name, args.partition_size)
+
+ def add_hash_footer(self, args):
+ """Implements the 'add_hash_footer' sub-command."""
+ args = self._fixup_common_args(args)
+ self.avb.add_hash_footer(
+ args.image.name if args.image else None, args.partition_size,
+ args.partition_name, args.hash_algorithm, args.salt,
+ args.chain_partition, args.algorithm, args.key,
+ args.public_key_metadata, args.rollback_index, args.flags,
+ args.rollback_index_location, args.prop, args.prop_from_file,
+ args.kernel_cmdline, args.setup_rootfs_from_kernel,
+ args.include_descriptors_from_image, args.calc_max_image_size,
+ args.signing_helper, args.signing_helper_with_files,
+ args.internal_release_string, args.append_to_release_string,
+ args.output_vbmeta_image, args.do_not_append_vbmeta_image,
+ args.print_required_libavb_version, args.use_persistent_digest,
+ args.do_not_use_ab)
+
+ def add_hashtree_footer(self, args):
+ """Implements the 'add_hashtree_footer' sub-command."""
+ args = self._fixup_common_args(args)
+ # TODO(zeuthen): Remove when removing support for the
+ # '--generate_fec' option above.
+ if args.generate_fec:
+ sys.stderr.write(
+ 'The --generate_fec option is deprecated since FEC '
+ 'is now generated by default. Use the option '
+ '--do_not_generate_fec to not generate FEC.\n')
+ self.avb.add_hashtree_footer(
+ args.image.name if args.image else None, args.partition_size,
+ args.partition_name, not args.do_not_generate_fec,
+ args.fec_num_roots, args.hash_algorithm, args.block_size, args.salt,
+ args.chain_partition, args.algorithm, args.key,
+ args.public_key_metadata, args.rollback_index, args.flags,
+ args.rollback_index_location, args.prop, args.prop_from_file,
+ args.kernel_cmdline, args.setup_rootfs_from_kernel,
+ args.setup_as_rootfs_from_kernel,
+ args.include_descriptors_from_image, args.calc_max_image_size,
+ args.signing_helper, args.signing_helper_with_files,
+ args.internal_release_string, args.append_to_release_string,
+ args.output_vbmeta_image, args.do_not_append_vbmeta_image,
+ args.print_required_libavb_version, args.use_persistent_digest,
+ args.do_not_use_ab, args.no_hashtree)
+
+ def erase_footer(self, args):
+ """Implements the 'erase_footer' sub-command."""
+ self.avb.erase_footer(args.image.name, args.keep_hashtree)
+
+ def zero_hashtree(self, args):
+ """Implements the 'zero_hashtree' sub-command."""
+ self.avb.zero_hashtree(args.image.name)
+
+ def extract_vbmeta_image(self, args):
+ """Implements the 'extract_vbmeta_image' sub-command."""
+ self.avb.extract_vbmeta_image(
+ args.output, args.image.name, args.padding_size)
+
+ def resize_image(self, args):
+ """Implements the 'resize_image' sub-command."""
+ self.avb.resize_image(args.image.name, args.partition_size)
+
+ def set_ab_metadata(self, args):
+ """Implements the 'set_ab_metadata' sub-command."""
+ self.avb.set_ab_metadata(args.misc_image, args.slot_data)
+
+ def info_image(self, args):
+ """Implements the 'info_image' sub-command."""
+ self.avb.info_image(args.image.name, args.output, args.atx)
+
+ def verify_image(self, args):
+ """Implements the 'verify_image' sub-command."""
+ self.avb.verify_image(
+ args.image.name, args.key, args.expected_chain_partition,
+ args.follow_chain_partitions, args.accept_zeroed_hashtree)
+
+ def print_partition_digests(self, args):
+ """Implements the 'print_partition_digests' sub-command."""
+ self.avb.print_partition_digests(
+ args.image.name, args.output, args.json)
+
+ def calculate_vbmeta_digest(self, args):
+ """Implements the 'calculate_vbmeta_digest' sub-command."""
+ self.avb.calculate_vbmeta_digest(
+ args.image.name, args.hash_algorithm, args.output)
+
+ def calculate_kernel_cmdline(self, args):
+ """Implements the 'calculate_kernel_cmdline' sub-command."""
+ self.avb.calculate_kernel_cmdline(
+ args.image.name, args.hashtree_disabled, args.output)
+
+ def make_atx_certificate(self, args):
+ """Implements the 'make_atx_certificate' sub-command."""
+ self.avb.make_atx_certificate(
+ args.output,
+ args.authority_key, args.subject_key.name, args.subject_key_version,
+ args.subject.read(), args.subject_is_intermediate_authority,
+ args.usage, args.signing_helper, args.signing_helper_with_files)
+
+ def make_atx_permanent_attributes(self, args):
+ """Implements the 'make_atx_permanent_attributes' sub-command."""
+ self.avb.make_atx_permanent_attributes(
+ args.output, args.root_authority_key.name, args.product_id.read())
+
+ def make_atx_metadata(self, args):
+ """Implements the 'make_atx_metadata' sub-command."""
+ self.avb.make_atx_metadata(
+ args.output, args.intermediate_key_certificate.read(),
+ args.product_key_certificate.read())
+
+ def make_atx_unlock_credential(self, args):
+ """Implements the 'make_atx_unlock_credential' sub-command."""
+ self.avb.make_atx_unlock_credential(
+ args.output, args.intermediate_key_certificate.read(),
+ args.unlock_key_certificate.read(), args.challenge, args.unlock_key,
+ args.signing_helper, args.signing_helper_with_files)
+
+
+if __name__ == '__main__':
+ if AVB_INVOCATION_LOGFILE:
+ with open(AVB_INVOCATION_LOGFILE, 'a') as log:
+ log.write(' '.join(sys.argv))
+ log.write('\n')
+
+ tool = AvbTool()
+ tool.run(sys.argv)
