25f35c7d0e
This new FW is build on the same codebasse than the actual InfiniTime. Only the display task is different (this allows to remove lvgl from the recovery fw, which is very heavy). CMake builds and docker have been modified accordingly. Note than the fw is converted into an image and then into a DFU in the cmake build (previously, it was only done in the
553 lines
21 KiB
Python
553 lines
21 KiB
Python
# Copyright 2018 Nordic Semiconductor ASA
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# Copyright 2017 Linaro Limited
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# Copyright 2019-2020 Arm Limited
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""
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Image signing and management.
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"""
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from . import version as versmod
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from .boot_record import create_sw_component_data
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import click
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from enum import Enum
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from intelhex import IntelHex
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import hashlib
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import struct
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import os.path
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from .keys import rsa, ecdsa, x25519
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from cryptography.hazmat.primitives.asymmetric import ec, padding
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from cryptography.hazmat.primitives.asymmetric.x25519 import X25519PrivateKey
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from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
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from cryptography.hazmat.primitives.kdf.hkdf import HKDF
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from cryptography.hazmat.primitives.serialization import Encoding, PublicFormat
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from cryptography.hazmat.backends import default_backend
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from cryptography.hazmat.primitives import hashes, hmac
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from cryptography.exceptions import InvalidSignature
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IMAGE_MAGIC = 0x96f3b83d
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IMAGE_HEADER_SIZE = 32
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BIN_EXT = "bin"
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INTEL_HEX_EXT = "hex"
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DEFAULT_MAX_SECTORS = 128
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MAX_ALIGN = 8
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DEP_IMAGES_KEY = "images"
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DEP_VERSIONS_KEY = "versions"
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MAX_SW_TYPE_LENGTH = 12 # Bytes
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# Image header flags.
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IMAGE_F = {
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'PIC': 0x0000001,
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'NON_BOOTABLE': 0x0000010,
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'RAM_LOAD': 0x0000020,
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'ENCRYPTED': 0x0000004,
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}
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TLV_VALUES = {
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'KEYHASH': 0x01,
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'PUBKEY': 0x02,
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'SHA256': 0x10,
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'RSA2048': 0x20,
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'ECDSA224': 0x21,
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'ECDSA256': 0x22,
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'RSA3072': 0x23,
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'ED25519': 0x24,
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'ENCRSA2048': 0x30,
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'ENCKW128': 0x31,
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'ENCEC256': 0x32,
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'ENCX25519': 0x33,
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'DEPENDENCY': 0x40,
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'SEC_CNT': 0x50,
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'BOOT_RECORD': 0x60,
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}
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TLV_SIZE = 4
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TLV_INFO_SIZE = 4
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TLV_INFO_MAGIC = 0x6907
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TLV_PROT_INFO_MAGIC = 0x6908
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boot_magic = bytes([
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0x77, 0xc2, 0x95, 0xf3,
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0x60, 0xd2, 0xef, 0x7f,
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0x35, 0x52, 0x50, 0x0f,
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0x2c, 0xb6, 0x79, 0x80, ])
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STRUCT_ENDIAN_DICT = {
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'little': '<',
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'big': '>'
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}
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VerifyResult = Enum('VerifyResult',
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"""
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OK INVALID_MAGIC INVALID_TLV_INFO_MAGIC INVALID_HASH
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INVALID_SIGNATURE
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""")
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class TLV():
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def __init__(self, endian, magic=TLV_INFO_MAGIC):
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self.magic = magic
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self.buf = bytearray()
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self.endian = endian
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def __len__(self):
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return TLV_INFO_SIZE + len(self.buf)
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def add(self, kind, payload):
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"""
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Add a TLV record. Kind should be a string found in TLV_VALUES above.
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"""
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e = STRUCT_ENDIAN_DICT[self.endian]
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buf = struct.pack(e + 'BBH', TLV_VALUES[kind], 0, len(payload))
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self.buf += buf
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self.buf += payload
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def get(self):
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if len(self.buf) == 0:
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return bytes()
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e = STRUCT_ENDIAN_DICT[self.endian]
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header = struct.pack(e + 'HH', self.magic, len(self))
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return header + bytes(self.buf)
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class Image():
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def __init__(self, version=None, header_size=IMAGE_HEADER_SIZE,
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pad_header=False, pad=False, confirm=False, align=1,
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slot_size=0, max_sectors=DEFAULT_MAX_SECTORS,
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overwrite_only=False, endian="little", load_addr=0,
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erased_val=None, save_enctlv=False, security_counter=None):
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self.version = version or versmod.decode_version("0")
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self.header_size = header_size
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self.pad_header = pad_header
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self.pad = pad
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self.confirm = confirm
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self.align = align
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self.slot_size = slot_size
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self.max_sectors = max_sectors
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self.overwrite_only = overwrite_only
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self.endian = endian
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self.base_addr = None
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self.load_addr = 0 if load_addr is None else load_addr
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self.erased_val = 0xff if erased_val is None else int(erased_val, 0)
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self.payload = []
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self.enckey = None
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self.save_enctlv = save_enctlv
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self.enctlv_len = 0
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if security_counter == 'auto':
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# Security counter has not been explicitly provided,
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# generate it from the version number
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self.security_counter = ((self.version.major << 24)
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+ (self.version.minor << 16)
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+ self.version.revision)
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else:
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self.security_counter = security_counter
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def __repr__(self):
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return "<Image version={}, header_size={}, security_counter={}, \
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base_addr={}, load_addr={}, align={}, slot_size={}, \
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max_sectors={}, overwrite_only={}, endian={} format={}, \
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payloadlen=0x{:x}>".format(
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self.version,
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self.header_size,
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self.security_counter,
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self.base_addr if self.base_addr is not None else "N/A",
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self.load_addr,
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self.align,
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self.slot_size,
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self.max_sectors,
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self.overwrite_only,
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self.endian,
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self.__class__.__name__,
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len(self.payload))
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def load(self, path):
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"""Load an image from a given file"""
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ext = os.path.splitext(path)[1][1:].lower()
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try:
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if ext == INTEL_HEX_EXT:
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ih = IntelHex(path)
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self.payload = ih.tobinarray()
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self.base_addr = ih.minaddr()
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else:
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with open(path, 'rb') as f:
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self.payload = f.read()
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except FileNotFoundError:
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raise click.UsageError("Input file not found")
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# Add the image header if needed.
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if self.pad_header and self.header_size > 0:
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if self.base_addr:
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# Adjust base_addr for new header
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self.base_addr -= self.header_size
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self.payload = bytes([self.erased_val] * self.header_size) + \
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self.payload
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self.check_header()
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def save(self, path, hex_addr=None):
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"""Save an image from a given file"""
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ext = os.path.splitext(path)[1][1:].lower()
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if ext == INTEL_HEX_EXT:
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# input was in binary format, but HEX needs to know the base addr
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if self.base_addr is None and hex_addr is None:
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raise click.UsageError("No address exists in input file "
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"neither was it provided by user")
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h = IntelHex()
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if hex_addr is not None:
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self.base_addr = hex_addr
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h.frombytes(bytes=self.payload, offset=self.base_addr)
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if self.pad:
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trailer_size = self._trailer_size(self.align, self.max_sectors,
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self.overwrite_only,
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self.enckey,
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self.save_enctlv,
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self.enctlv_len)
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trailer_addr = (self.base_addr + self.slot_size) - trailer_size
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padding = bytes([self.erased_val] *
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(trailer_size - len(boot_magic))) + boot_magic
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h.puts(trailer_addr, padding)
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h.tofile(path, 'hex')
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else:
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if self.pad:
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self.pad_to(self.slot_size)
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with open(path, 'wb') as f:
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f.write(self.payload)
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def check_header(self):
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if self.header_size > 0 and not self.pad_header:
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if any(v != 0 for v in self.payload[0:self.header_size]):
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raise click.UsageError("Header padding was not requested and "
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"image does not start with zeros")
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def check_trailer(self):
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if self.slot_size > 0:
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tsize = self._trailer_size(self.align, self.max_sectors,
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self.overwrite_only, self.enckey,
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self.save_enctlv, self.enctlv_len)
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padding = self.slot_size - (len(self.payload) + tsize)
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if padding < 0:
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msg = "Image size (0x{:x}) + trailer (0x{:x}) exceeds " \
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"requested size 0x{:x}".format(
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len(self.payload), tsize, self.slot_size)
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raise click.UsageError(msg)
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def ecies_hkdf(self, enckey, plainkey):
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if isinstance(enckey, ecdsa.ECDSA256P1Public):
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newpk = ec.generate_private_key(ec.SECP256R1(), default_backend())
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shared = newpk.exchange(ec.ECDH(), enckey._get_public())
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else:
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newpk = X25519PrivateKey.generate()
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shared = newpk.exchange(enckey._get_public())
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derived_key = HKDF(
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algorithm=hashes.SHA256(), length=48, salt=None,
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info=b'MCUBoot_ECIES_v1', backend=default_backend()).derive(shared)
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encryptor = Cipher(algorithms.AES(derived_key[:16]),
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modes.CTR(bytes([0] * 16)),
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backend=default_backend()).encryptor()
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cipherkey = encryptor.update(plainkey) + encryptor.finalize()
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mac = hmac.HMAC(derived_key[16:], hashes.SHA256(),
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backend=default_backend())
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mac.update(cipherkey)
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ciphermac = mac.finalize()
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if isinstance(enckey, ecdsa.ECDSA256P1Public):
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pubk = newpk.public_key().public_bytes(
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encoding=Encoding.X962,
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format=PublicFormat.UncompressedPoint)
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else:
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pubk = newpk.public_key().public_bytes(
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encoding=Encoding.Raw,
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format=PublicFormat.Raw)
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return cipherkey, ciphermac, pubk
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def create(self, key, public_key_format, enckey, dependencies=None,
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sw_type=None):
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self.enckey = enckey
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# Calculate the hash of the public key
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if key is not None:
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pub = key.get_public_bytes()
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sha = hashlib.sha256()
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sha.update(pub)
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pubbytes = sha.digest()
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else:
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pubbytes = bytes(hashlib.sha256().digest_size)
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protected_tlv_size = 0
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if self.security_counter is not None:
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# Size of the security counter TLV: header ('HH') + payload ('I')
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# = 4 + 4 = 8 Bytes
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protected_tlv_size += TLV_SIZE + 4
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if sw_type is not None:
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if len(sw_type) > MAX_SW_TYPE_LENGTH:
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msg = "'{}' is too long ({} characters) for sw_type. Its " \
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"maximum allowed length is 12 characters.".format(
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sw_type, len(sw_type))
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raise click.UsageError(msg)
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image_version = (str(self.version.major) + '.'
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+ str(self.version.minor) + '.'
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+ str(self.version.revision))
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# The image hash is computed over the image header, the image
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# itself and the protected TLV area. However, the boot record TLV
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# (which is part of the protected area) should contain this hash
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# before it is even calculated. For this reason the script fills
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# this field with zeros and the bootloader will insert the right
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# value later.
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digest = bytes(hashlib.sha256().digest_size)
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# Create CBOR encoded boot record
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boot_record = create_sw_component_data(sw_type, image_version,
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"SHA256", digest,
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pubbytes)
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protected_tlv_size += TLV_SIZE + len(boot_record)
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if dependencies is not None:
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# Size of a Dependency TLV = Header ('HH') + Payload('IBBHI')
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# = 4 + 12 = 16 Bytes
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dependencies_num = len(dependencies[DEP_IMAGES_KEY])
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protected_tlv_size += (dependencies_num * 16)
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if protected_tlv_size != 0:
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# Add the size of the TLV info header
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protected_tlv_size += TLV_INFO_SIZE
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# At this point the image is already on the payload, this adds
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# the header to the payload as well
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self.add_header(enckey, protected_tlv_size)
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prot_tlv = TLV(self.endian, TLV_PROT_INFO_MAGIC)
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# Protected TLVs must be added first, because they are also included
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# in the hash calculation
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protected_tlv_off = None
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if protected_tlv_size != 0:
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e = STRUCT_ENDIAN_DICT[self.endian]
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if self.security_counter is not None:
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payload = struct.pack(e + 'I', self.security_counter)
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prot_tlv.add('SEC_CNT', payload)
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if sw_type is not None:
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prot_tlv.add('BOOT_RECORD', boot_record)
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if dependencies is not None:
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for i in range(dependencies_num):
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payload = struct.pack(
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e + 'B3x'+'BBHI',
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int(dependencies[DEP_IMAGES_KEY][i]),
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dependencies[DEP_VERSIONS_KEY][i].major,
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dependencies[DEP_VERSIONS_KEY][i].minor,
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dependencies[DEP_VERSIONS_KEY][i].revision,
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dependencies[DEP_VERSIONS_KEY][i].build
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)
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prot_tlv.add('DEPENDENCY', payload)
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protected_tlv_off = len(self.payload)
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self.payload += prot_tlv.get()
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tlv = TLV(self.endian)
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# Note that ecdsa wants to do the hashing itself, which means
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# we get to hash it twice.
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sha = hashlib.sha256()
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sha.update(self.payload)
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digest = sha.digest()
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tlv.add('SHA256', digest)
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if key is not None:
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if public_key_format == 'hash':
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tlv.add('KEYHASH', pubbytes)
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else:
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tlv.add('PUBKEY', pub)
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# `sign` expects the full image payload (sha256 done internally),
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# while `sign_digest` expects only the digest of the payload
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if hasattr(key, 'sign'):
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sig = key.sign(bytes(self.payload))
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else:
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sig = key.sign_digest(digest)
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tlv.add(key.sig_tlv(), sig)
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# At this point the image was hashed + signed, we can remove the
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# protected TLVs from the payload (will be re-added later)
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if protected_tlv_off is not None:
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self.payload = self.payload[:protected_tlv_off]
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if enckey is not None:
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plainkey = os.urandom(16)
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if isinstance(enckey, rsa.RSAPublic):
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cipherkey = enckey._get_public().encrypt(
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plainkey, padding.OAEP(
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mgf=padding.MGF1(algorithm=hashes.SHA256()),
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algorithm=hashes.SHA256(),
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label=None))
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self.enctlv_len = len(cipherkey)
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tlv.add('ENCRSA2048', cipherkey)
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elif isinstance(enckey, (ecdsa.ECDSA256P1Public,
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x25519.X25519Public)):
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cipherkey, mac, pubk = self.ecies_hkdf(enckey, plainkey)
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enctlv = pubk + mac + cipherkey
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self.enctlv_len = len(enctlv)
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if isinstance(enckey, ecdsa.ECDSA256P1Public):
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tlv.add('ENCEC256', enctlv)
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else:
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tlv.add('ENCX25519', enctlv)
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nonce = bytes([0] * 16)
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cipher = Cipher(algorithms.AES(plainkey), modes.CTR(nonce),
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backend=default_backend())
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encryptor = cipher.encryptor()
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img = bytes(self.payload[self.header_size:])
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self.payload[self.header_size:] = \
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encryptor.update(img) + encryptor.finalize()
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self.payload += prot_tlv.get()
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self.payload += tlv.get()
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self.check_trailer()
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def add_header(self, enckey, protected_tlv_size):
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"""Install the image header."""
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flags = 0
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if enckey is not None:
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flags |= IMAGE_F['ENCRYPTED']
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if self.load_addr != 0:
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# Indicates that this image should be loaded into RAM
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# instead of run directly from flash.
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flags |= IMAGE_F['RAM_LOAD']
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e = STRUCT_ENDIAN_DICT[self.endian]
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fmt = (e +
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# type ImageHdr struct {
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'I' + # Magic uint32
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'I' + # LoadAddr uint32
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'H' + # HdrSz uint16
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'H' + # PTLVSz uint16
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'I' + # ImgSz uint32
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'I' + # Flags uint32
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'BBHI' + # Vers ImageVersion
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'I' # Pad1 uint32
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) # }
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assert struct.calcsize(fmt) == IMAGE_HEADER_SIZE
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header = struct.pack(fmt,
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IMAGE_MAGIC,
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self.load_addr,
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self.header_size,
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protected_tlv_size, # TLV Info header + Protected TLVs
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len(self.payload) - self.header_size, # ImageSz
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flags,
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self.version.major,
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self.version.minor or 0,
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self.version.revision or 0,
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self.version.build or 0,
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0) # Pad1
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self.payload = bytearray(self.payload)
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self.payload[:len(header)] = header
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def _trailer_size(self, write_size, max_sectors, overwrite_only, enckey,
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save_enctlv, enctlv_len):
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# NOTE: should already be checked by the argument parser
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magic_size = 16
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if overwrite_only:
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return MAX_ALIGN * 2 + magic_size
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else:
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if write_size not in set([1, 2, 4, 8]):
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raise click.BadParameter("Invalid alignment: {}".format(
|
|
write_size))
|
|
m = DEFAULT_MAX_SECTORS if max_sectors is None else max_sectors
|
|
trailer = m * 3 * write_size # status area
|
|
if enckey is not None:
|
|
if save_enctlv:
|
|
# TLV saved by the bootloader is aligned
|
|
keylen = (int((enctlv_len - 1) / MAX_ALIGN) + 1) * MAX_ALIGN
|
|
else:
|
|
keylen = 16
|
|
trailer += keylen * 2 # encryption keys
|
|
trailer += MAX_ALIGN * 4 # image_ok/copy_done/swap_info/swap_size
|
|
trailer += magic_size
|
|
return trailer
|
|
|
|
def pad_to(self, size):
|
|
"""Pad the image to the given size, with the given flash alignment."""
|
|
tsize = self._trailer_size(self.align, self.max_sectors,
|
|
self.overwrite_only, self.enckey,
|
|
self.save_enctlv, self.enctlv_len)
|
|
padding = size - (len(self.payload) + tsize)
|
|
pbytes = bytearray([self.erased_val] * padding)
|
|
pbytes += bytearray([self.erased_val] * (tsize - len(boot_magic)))
|
|
if self.confirm and not self.overwrite_only:
|
|
pbytes[-MAX_ALIGN] = 0x01 # image_ok = 0x01
|
|
pbytes += boot_magic
|
|
self.payload += pbytes
|
|
|
|
@staticmethod
|
|
def verify(imgfile, key):
|
|
with open(imgfile, "rb") as f:
|
|
b = f.read()
|
|
|
|
magic, _, header_size, _, img_size = struct.unpack('IIHHI', b[:16])
|
|
version = struct.unpack('BBHI', b[20:28])
|
|
|
|
if magic != IMAGE_MAGIC:
|
|
return VerifyResult.INVALID_MAGIC, None
|
|
|
|
tlv_info = b[header_size+img_size:header_size+img_size+TLV_INFO_SIZE]
|
|
magic, tlv_tot = struct.unpack('HH', tlv_info)
|
|
if magic != TLV_INFO_MAGIC:
|
|
return VerifyResult.INVALID_TLV_INFO_MAGIC, None
|
|
|
|
sha = hashlib.sha256()
|
|
sha.update(b[:header_size+img_size])
|
|
digest = sha.digest()
|
|
|
|
tlv_off = header_size + img_size
|
|
tlv_end = tlv_off + tlv_tot
|
|
tlv_off += TLV_INFO_SIZE # skip tlv info
|
|
while tlv_off < tlv_end:
|
|
tlv = b[tlv_off:tlv_off+TLV_SIZE]
|
|
tlv_type, _, tlv_len = struct.unpack('BBH', tlv)
|
|
if tlv_type == TLV_VALUES["SHA256"]:
|
|
off = tlv_off + TLV_SIZE
|
|
if digest == b[off:off+tlv_len]:
|
|
if key is None:
|
|
return VerifyResult.OK, version
|
|
else:
|
|
return VerifyResult.INVALID_HASH, None
|
|
elif key is not None and tlv_type == TLV_VALUES[key.sig_tlv()]:
|
|
off = tlv_off + TLV_SIZE
|
|
tlv_sig = b[off:off+tlv_len]
|
|
payload = b[:header_size+img_size]
|
|
try:
|
|
if hasattr(key, 'verify'):
|
|
key.verify(tlv_sig, payload)
|
|
else:
|
|
key.verify_digest(tlv_sig, digest)
|
|
return VerifyResult.OK, version
|
|
except InvalidSignature:
|
|
# continue to next TLV
|
|
pass
|
|
tlv_off += TLV_SIZE + tlv_len
|
|
return VerifyResult.INVALID_SIGNATURE, None
|