Add image signing scripts from TF-M bl2 library

pull/9772/head
Michael Schwarcz 2019-02-21 14:28:37 +02:00
parent d2c433ccfe
commit 7016ac7d8c
9 changed files with 671 additions and 0 deletions

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@ -21,3 +21,4 @@ fuzzywuzzy>=0.11,<=0.17
pyelftools>=0.24,<=0.25
git+https://github.com/armmbed/manifest-tool.git@v1.4.6
icetea>=1.2.1,<1.3
pycryptodome>=3.7.2,<=3.7.3

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# Copyright (c) 2017-2018 ARM Limited
#
# SPDX-License-Identifier: Apache-2.0
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from .assemble import Assembly
__all__ = [
'Assembly'
]

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#! /usr/bin/env python3
#
# Copyright 2017 Linaro Limited
# Copyright (c) 2017-2018, Arm Limited.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
Assemble multiple images into a single image that can be flashed on the device.
"""
import argparse
import errno
import io
import re
import os
import shutil
offset_re = re.compile(r"^#define ([0-9A-Z_]+)_IMAGE_OFFSET\s+((0x)?[0-9a-fA-F]+)")
size_re = re.compile(r"^#define ([0-9A-Z_]+)_IMAGE_MAX_SIZE\s+((0x)?[0-9a-fA-F]+)")
class Assembly():
def __init__(self, layout_path, output):
self.output = output
self.layout_path = layout_path
self.find_slots()
try:
os.unlink(output)
except OSError as e:
if e.errno != errno.ENOENT:
raise
def find_slots(self):
offsets = {}
sizes = {}
if os.path.isabs(self.layout_path):
configFile = self.layout_path
else:
scriptsDir = os.path.dirname(os.path.abspath(__file__))
configFile = os.path.join(scriptsDir, self.layout_path)
with open(configFile, 'r') as fd:
for line in fd:
m = offset_re.match(line)
if m is not None:
offsets[m.group(1)] = int(m.group(2), 0)
m = size_re.match(line)
if m is not None:
sizes[m.group(1)] = int(m.group(2), 0)
if 'SECURE' not in offsets:
raise Exception("Image config does not have secure partition")
if 'NON_SECURE' not in offsets:
raise Exception("Image config does not have non-secure partition")
self.offsets = offsets
self.sizes = sizes
def add_image(self, source, partition):
with open(self.output, 'ab') as ofd:
ofd.seek(0, os.SEEK_END)
pos = ofd.tell()
if pos > self.offsets[partition]:
raise Exception("Partitions not in order, unsupported")
if pos < self.offsets[partition]:
ofd.write(b'\xFF' * (self.offsets[partition] - pos))
statinfo = os.stat(source)
if statinfo.st_size > self.sizes[partition]:
raise Exception("Image {} is too large for partition".format(source))
with open(source, 'rb') as rfd:
shutil.copyfileobj(rfd, ofd, 0x10000)
def main():
parser = argparse.ArgumentParser()
parser.add_argument('-l', '--layout', required=True,
help='Location of the memory layout file')
parser.add_argument('-s', '--secure', required=True,
help='Unsigned secure image')
parser.add_argument('-n', '--non_secure',
help='Unsigned non-secure image')
parser.add_argument('-o', '--output', required=True,
help='Filename to write full image to')
args = parser.parse_args()
output = Assembly(args.layout, args.output)
output.add_image(args.secure, "SECURE")
output.add_image(args.non_secure, "NON_SECURE")
if __name__ == '__main__':
main()

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#! /usr/bin/env python3
#
# Copyright 2017 Linaro Limited
# Copyright (c) 2018, Arm Limited.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from __future__ import print_function
import os
import re
import argparse
from imgtool_lib import keys
from imgtool_lib import image
from imgtool_lib import version
import sys
def find_load_address(args):
load_address_re = re.compile(r"^#define\sIMAGE_LOAD_ADDRESS\s+(0x[0-9a-fA-F]+)")
if os.path.isabs(args.layout):
configFile = args.layout
else:
scriptsDir = os.path.dirname(os.path.abspath(__file__))
configFile = os.path.join(scriptsDir, args.layout)
ramLoadAddress = None
with open(configFile, 'r') as flash_layout_file:
for line in flash_layout_file:
m = load_address_re.match(line)
if m is not None:
ramLoadAddress = int(m.group(1), 0)
print("**[INFO]** Writing load address from the macro in "
"flash_layout.h to the image header.. "
+ hex(ramLoadAddress)
+ " (dec. " + str(ramLoadAddress) + ")")
break
return ramLoadAddress
# Returns the last version number if present, or None if not
def get_last_version(path):
if (os.path.isfile(path) == False): # Version file not present
return None
else: # Version file is present, check it has a valid number inside it
with open(path, "r") as oldFile:
fileContents = oldFile.read()
if version.version_re.match(fileContents): # number is valid
return version.decode_version(fileContents)
else:
return None
def next_version_number(args, defaultVersion, path):
newVersion = None
if (version.compare(args.version, defaultVersion) == 0): # Default version
lastVersion = get_last_version(path)
if (lastVersion is not None):
newVersion = version.increment_build_num(lastVersion)
else:
newVersion = version.increment_build_num(defaultVersion)
else: # Version number has been explicitly provided (not using the default)
newVersion = args.version
versionString = "{a}.{b}.{c}+{d}".format(
a=str(newVersion.major),
b=str(newVersion.minor),
c=str(newVersion.revision),
d=str(newVersion.build)
)
with open(path, "w") as newFile:
newFile.write(versionString)
print("**[INFO]** Image version number set to " + versionString)
return newVersion
def gen_rsa2048(args):
keys.RSA2048.generate().export_private(args.key)
keygens = {
'rsa-2048': gen_rsa2048, }
def do_keygen(args):
if args.type not in keygens:
msg = "Unexpected key type: {}".format(args.type)
raise argparse.ArgumentTypeError(msg)
keygens[args.type](args)
def do_getpub(args):
key = keys.load(args.key)
if args.lang == 'c':
key.emit_c()
else:
msg = "Unsupported language, valid are: c"
raise argparse.ArgumentTypeError(msg)
def do_sign(args):
if args.rsa_pkcs1_15:
keys.sign_rsa_pss = False
img = image.Image.load(args.infile,
version=next_version_number(args,
version.decode_version("0"),
"lastVerNum.txt"),
header_size=args.header_size,
included_header=args.included_header,
pad=args.pad)
key = keys.load(args.key) if args.key else None
img.sign(key, find_load_address(args))
if args.pad:
img.pad_to(args.pad, args.align)
img.save(args.outfile)
subcmds = {
'keygen': do_keygen,
'getpub': do_getpub,
'sign': do_sign, }
def alignment_value(text):
value = int(text)
if value not in [1, 2, 4, 8]:
msg = "{} must be one of 1, 2, 4 or 8".format(value)
raise argparse.ArgumentTypeError(msg)
return value
def intparse(text):
"""Parse a command line argument as an integer.
Accepts 0x and other prefixes to allow other bases to be used."""
return int(text, 0)
def args():
parser = argparse.ArgumentParser()
subs = parser.add_subparsers(help='subcommand help', dest='subcmd')
keygenp = subs.add_parser('keygen', help='Generate pub/private keypair')
keygenp.add_argument('-k', '--key', metavar='filename', required=True)
keygenp.add_argument('-t', '--type', metavar='type',
choices=keygens.keys(), required=True)
getpub = subs.add_parser('getpub', help='Get public key from keypair')
getpub.add_argument('-k', '--key', metavar='filename', required=True)
getpub.add_argument('-l', '--lang', metavar='lang', default='c')
sign = subs.add_parser('sign', help='Sign an image with a private key')
sign.add_argument('--layout', required=True,
help='Location of the memory layout file')
sign.add_argument('-k', '--key', metavar='filename')
sign.add_argument("--align", type=alignment_value, required=True)
sign.add_argument("-v", "--version", type=version.decode_version,
default="0.0.0+0")
sign.add_argument("-H", "--header-size", type=intparse, required=True)
sign.add_argument("--included-header", default=False, action='store_true',
help='Image has gap for header')
sign.add_argument("--pad", type=intparse,
help='Pad image to this many bytes, adding trailer magic')
sign.add_argument("--rsa-pkcs1-15",
help='Use old PKCS#1 v1.5 signature algorithm',
default=False, action='store_true')
sign.add_argument("infile")
sign.add_argument("outfile")
args = parser.parse_args()
if args.subcmd is None:
print('Must specify a subcommand', file=sys.stderr)
sys.exit(1)
subcmds[args.subcmd](args)
if __name__ == '__main__':
args()

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# Copyright 2017 Linaro Limited
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# This file is intentionally empty.
#
# The __init__.py files are required to make Python treat the directories as
# containing packages.

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@ -0,0 +1,179 @@
# Copyright 2017 Linaro Limited
# Copyright (c) 2018, Arm Limited.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
Image signing and management.
"""
from . import version as versmod
import hashlib
import struct
IMAGE_MAGIC = 0x96f3b83d
IMAGE_HEADER_SIZE = 32
# Image header flags.
IMAGE_F = {
'PIC': 0x0000001,
'NON_BOOTABLE': 0x0000010,
'RAM_LOAD': 0x0000020, }
TLV_VALUES = {
'KEYHASH': 0x01,
'SHA256' : 0x10,
'RSA2048': 0x20, }
TLV_INFO_SIZE = 4
TLV_INFO_MAGIC = 0x6907
# Sizes of the image trailer, depending on flash write size.
trailer_sizes = {
write_size: 128 * 3 * write_size + 8 * 2 + 16
for write_size in [1, 2, 4, 8]
}
boot_magic = bytearray([
0x77, 0xc2, 0x95, 0xf3,
0x60, 0xd2, 0xef, 0x7f,
0x35, 0x52, 0x50, 0x0f,
0x2c, 0xb6, 0x79, 0x80, ])
class TLV():
def __init__(self):
self.buf = bytearray()
def add(self, kind, payload):
"""Add a TLV record. Kind should be a string found in TLV_VALUES above."""
buf = struct.pack('<BBH', TLV_VALUES[kind], 0, len(payload))
self.buf += buf
self.buf += payload
def get(self):
header = struct.pack('<HH', TLV_INFO_MAGIC, TLV_INFO_SIZE + len(self.buf))
return header + bytes(self.buf)
class Image():
@classmethod
def load(cls, path, included_header=False, **kwargs):
"""Load an image from a given file"""
with open(path, 'rb') as f:
payload = f.read()
obj = cls(**kwargs)
obj.payload = payload
# Add the image header if needed.
if not included_header and obj.header_size > 0:
obj.payload = (b'\000' * obj.header_size) + obj.payload
obj.check()
return obj
def __init__(self, version, header_size=IMAGE_HEADER_SIZE, pad=0):
self.version = version
self.header_size = header_size or IMAGE_HEADER_SIZE
self.pad = pad
def __repr__(self):
return "<Image version={}, header_size={}, pad={}, payloadlen=0x{:x}>".format(
self.version,
self.header_size,
self.pad,
len(self.payload))
def save(self, path):
with open(path, 'wb') as f:
f.write(self.payload)
def check(self):
"""Perform some sanity checking of the image."""
# If there is a header requested, make sure that the image
# starts with all zeros.
if self.header_size > 0:
if any(v != 0 and v != b'\000' for v in self.payload[0:self.header_size]):
raise Exception("Padding requested, but image does not start with zeros")
def sign(self, key, ramLoadAddress):
self.add_header(key, ramLoadAddress)
tlv = TLV()
sha = hashlib.sha256()
sha.update(self.payload)
digest = sha.digest()
tlv.add('SHA256', digest)
if key is not None:
pub = key.get_public_bytes()
sha = hashlib.sha256()
sha.update(pub)
pubbytes = sha.digest()
tlv.add('KEYHASH', pubbytes)
sig = key.sign(self.payload)
tlv.add(key.sig_tlv(), sig)
self.payload += tlv.get()
def add_header(self, key, ramLoadAddress):
"""Install the image header.
The key is needed to know the type of signature, and
approximate the size of the signature."""
flags = 0
if ramLoadAddress is not None:
# add the load address flag to the header to indicate that an SRAM
# load address macro has been defined
flags |= IMAGE_F["RAM_LOAD"]
fmt = ('<' +
# type ImageHdr struct {
'I' + # Magic uint32
'I' + # LoadAddr uint32
'H' + # HdrSz uint16
'H' + # Pad1 uint16
'I' + # ImgSz uint32
'I' + # Flags uint32
'BBHI' + # Vers ImageVersion
'I' # Pad2 uint32
) # }
assert struct.calcsize(fmt) == IMAGE_HEADER_SIZE
header = struct.pack(fmt,
IMAGE_MAGIC,
0 if (ramLoadAddress is None) else ramLoadAddress, # LoadAddr
self.header_size,
0, # Pad1
len(self.payload) - self.header_size, # ImageSz
flags, # Flags
self.version.major,
self.version.minor or 0,
self.version.revision or 0,
self.version.build or 0,
0) # Pad2
self.payload = bytearray(self.payload)
self.payload[:len(header)] = header
def pad_to(self, size, align):
"""Pad the image to the given size, with the given flash alignment."""
tsize = trailer_sizes[align]
padding = size - (len(self.payload) + tsize)
if padding < 0:
msg = "Image size (0x{:x}) + trailer (0x{:x}) exceeds requested size 0x{:x}".format(
len(self.payload), tsize, size)
raise Exception(msg)
pbytes = b'\xff' * padding
pbytes += b'\xff' * (tsize - len(boot_magic))
pbytes += boot_magic
self.payload += pbytes

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# Copyright 2017 Linaro Limited
# Copyright (c) 2017-2018, Arm Limited.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
Cryptographic key management for imgtool.
"""
from __future__ import print_function
from Crypto.Hash import SHA256
from Crypto.PublicKey import RSA
from Crypto.Signature import PKCS1_v1_5, PKCS1_PSS
import hashlib
from pyasn1.type import namedtype, univ
from pyasn1.codec.der.encoder import encode
# By default, we use RSA-PSS (PKCS 2.1). That can be overridden on
# the command line to support the older (less secure) PKCS1.5
sign_rsa_pss = True
AUTOGEN_MESSAGE = "/* Autogenerated by imgtool.py, do not edit. */"
class RSAPublicKey(univ.Sequence):
componentType = namedtype.NamedTypes(
namedtype.NamedType('modulus', univ.Integer()),
namedtype.NamedType('publicExponent', univ.Integer()))
class RSA2048():
def __init__(self, key):
"""Construct an RSA2048 key with the given key data"""
self.key = key
@staticmethod
def generate():
return RSA2048(RSA.generate(2048))
def export_private(self, path):
with open(path, 'wb') as f:
f.write(self.key.exportKey('PEM'))
def get_public_bytes(self):
node = RSAPublicKey()
node['modulus'] = self.key.n
node['publicExponent'] = self.key.e
return bytearray(encode(node))
def emit_c(self):
print(AUTOGEN_MESSAGE)
print("const unsigned char rsa_pub_key[] = {", end='')
encoded = self.get_public_bytes()
for count, b in enumerate(encoded):
if count % 8 == 0:
print("\n\t", end='')
else:
print(" ", end='')
print("0x{:02x},".format(b), end='')
print("\n};")
print("const unsigned int rsa_pub_key_len = {};".format(len(encoded)))
def sig_type(self):
"""Return the type of this signature (as a string)"""
if sign_rsa_pss:
return "PKCS1_PSS_RSA2048_SHA256"
else:
return "PKCS15_RSA2048_SHA256"
def sig_len(self):
return 256
def sig_tlv(self):
return "RSA2048"
def sign(self, payload):
converted_payload = bytes(payload)
sha = SHA256.new(converted_payload)
if sign_rsa_pss:
signer = PKCS1_PSS.new(self.key)
else:
signer = PKCS1_v1_5.new(self.key)
signature = signer.sign(sha)
assert len(signature) == self.sig_len()
return signature
def load(path):
with open(path, 'rb') as f:
pem = f.read()
try:
key = RSA.importKey(pem)
if key.n.bit_length() != 2048:
raise Exception("Unsupported RSA bit length, only 2048 supported")
return RSA2048(key)
except ValueError:
raise Exception("Unsupported RSA key file")

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# Copyright 2017 Linaro Limited
# Copyright (c) 2018, Arm Limited.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
Semi Semantic Versioning
Implements a subset of semantic versioning that is supportable by the image header.
"""
import argparse
from collections import namedtuple
import re
SemiSemVersion = namedtuple('SemiSemVersion', ['major', 'minor', 'revision', 'build'])
def increment_build_num(lastVer):
newVer = SemiSemVersion(lastVer.major, lastVer.minor, lastVer.revision, lastVer.build + 1)
return newVer
# -1 if a is older than b; 0 if they're the same version; 1 if a is newer than b
def compare(a, b):
if (a.major > b.major): return 1
elif (a.major < b.major): return -1
else:
if (a.minor > b.minor): return 1
elif (a.minor < b.minor): return -1
else:
if (a.revision > b.revision): return 1
elif (a.revision < b.revision): return -1
else:
if (a.build > b.build): return 1
elif (a.build < b.build): return -1
else: return 0
version_re = re.compile(r"""^([1-9]\d*|0)(\.([1-9]\d*|0)(\.([1-9]\d*|0)(\+([1-9]\d*|0))?)?)?$""")
def decode_version(text):
"""Decode the version string, which should be of the form maj.min.rev+build"""
m = version_re.match(text)
if m:
result = SemiSemVersion(
int(m.group(1)) if m.group(1) else 0,
int(m.group(3)) if m.group(3) else 0,
int(m.group(5)) if m.group(5) else 0,
int(m.group(7)) if m.group(7) else 0)
return result
else:
msg = "Invalid version number, should be maj.min.rev+build with later parts optional"
raise argparse.ArgumentTypeError(msg)
if __name__ == '__main__':
print(decode_version("1.2"))
print(decode_version("1.0"))
print(decode_version("0.0.2+75"))
print(decode_version("0.0.0+00"))